Display

Abstract

To provide a display that prevents a variation in current value caused by a variation in threshold value voltage of a transistor, and reduces deviation from the brightness designated by a video signal.SOLUTION: A display has pixels each including a transistor that controls the value of a current supplied to a load, a first holding capacity, a second holding capacity, and a first switch to a fourth switch, and causes the second holding capacity to hold a threshold value voltage of the transistor and subsequently inputs a potential according to a video signal to the pixel. In this way, the display causes the second holding capacity to hold a voltage obtained by adding a potential capacitively divided with the first holding capacity, of the potential according to the video signal, to the threshold value voltage, to thereby prevent a variation in current value caused by a variation in threshold value voltage of the transistor. A desired current can thus be supplied to loads including a light-emitting device. A display can be provided which reduces deviation from the brightness designated by the video signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a semiconductor device having a function of controlling a current supplied to a load by a transistor. , a pixel formed by a display element whose luminance changes depending on a signal, and a signal for driving the pixel The present invention relates to a display device including a scanning line driving circuit and a scanning line driving circuit, and also to a driving method thereof. More particularly, the present invention relates to an electronic device having the display device in a display unit. [Background technology]

[0002] In recent years, pixels have been replaced with electroluminescence (EL) Self-luminous display devices using light-emitting elements such as luminescence (LED) have been attracting attention. The light emitting element used in such a self-luminous display device is an organic light emitting diode. OLED (Organic Light Emitting Diode) and EL These elements have attracted attention and are now being used in EL displays and other applications. These light-emitting elements emit light themselves, so the pixels are more visible than LCDs, and It also has the advantage of fast response time. are often controlled by the value of the current flowing through them.

[0003] In addition, an active matrix transistor is provided for each pixel to control the light emission of the light-emitting element. Active matrix display devices are being developed. Not only does it enable high-definition and large-screen displays that are difficult to achieve with conventional matrix display devices, It is expected to be put into practical use because it operates with lower power consumption than passive matrix display devices. .

[0004] The pixel configuration of a conventional active matrix display device is shown in FIG. 62 (Patent Document 1). The pixel shown in 62 is a thin film transistor (Thin Film Transistor: The TFT 11, the TFT 12, the capacitance element 13, and the light-emitting element 14 are provided. 16. Either the source electrode or the drain electrode of the TFT 12 is connected to the A power supply potential Vdd is supplied to one electrode of the capacitor element 13 and the other electrode of the light emitting element 14. The electrodes are supplied with a ground potential.

[0005] At this time, the semiconductor of the TFT 12 that controls the current value supplied to the light emitting element, that is, the driving TFT When amorphous silicon is used for the body layer, the threshold voltage (Vth) fluctuates due to degradation, etc. In this case, even though the same potential is applied to different pixels from the signal line 15, The current flowing through the light emitting element 14 varies from pixel to pixel, causing the displayed brightness to be non-uniform from pixel to pixel. Even when polysilicon is used for the semiconductor layer of the driving TFT, The characteristics of the star may deteriorate or vary.

[0006] In order to solve this problem, Patent Document 2 proposes an operation method using the pixel shown in FIG. The pixel shown in FIG. 63 controls the value of the current supplied to the transistor 21 and the light emitting element 24. The pixel has a driving transistor 22 for controlling the pixel, a capacitor element 23, and a light emitting element 24. , and is connected to the scanning line 26. The driving transistor 22 is an NMOS transistor. and either the source electrode or the drain electrode of the driving transistor 22 is A ground potential is supplied to the light emitting element 24, and Vca is supplied to the counter electrode of the light emitting element 24.

[0007] A timing chart for the operation of this pixel is shown in Figure 64. In Figure 64, The programming period consists of an initialization period 31, a threshold voltage (Vth) programming period 32, and a data programming period 33. The period is divided into a reading period 33 and a light emitting period 34. Note that one frame period is the period during which one screen's worth of image is displayed. This corresponds to the display period, and includes the initialization period, threshold voltage (Vth) write period, and data write period. The write period and the write period are collectively called the address period.

[0008] First, in the threshold voltage writing period 32, the threshold voltage of the driving transistor 22 is Then, in the data writing period 33, the brightness of the pixel is written to the capacitor element. The data voltage (Vdata) shown in the figure is written to the capacitor, and Vdata+Vth is the voltage of the capacitor. During the light emission period, the driving transistor 22 is turned on, and Vca By changing the data voltage, the light emitting element 24 emits light at the brightness specified by the data voltage. This operation reduces the luminance variation caused by the fluctuation of the threshold voltage of the driving transistor. It is decreasing.

[0009] In Patent Document 3, the voltage obtained by adding the data potential to the threshold voltage of the driving TFT is also Even if the TFT threshold voltage fluctuates, the current that flows is It is disclosed that there is no change. As described above, in a display device, the current value caused by the variation in the threshold voltage of the driving TFT There was a need to reduce the variation. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 8-234683 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-295131 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-280059 Summary of the Invention [Problem to be solved by the invention]

[0011] In both of the operation methods described in Patent Documents 2 and 3, the potential of Vca By changing the value several times per frame period, the above-mentioned initialization and writing of the threshold voltage can be performed. In these pixels, one of the light emitting elements to which Vca is supplied The other electrode, i.e., the counter electrode, is formed over the entire pixel area, so initialization and threshold voltage If there is even one pixel in which data is being written other than the original, the light-emitting element Therefore, as shown in Figure 65, The ratio of the light emitting period (i.e., the duty ratio) becomes small.

[0012] If the duty ratio is low, it is necessary to increase the current value flowing through the light-emitting element and the driving transistor. Therefore, the voltage applied to the light-emitting element increases, resulting in increased power consumption. This can cause image burn-in or a loss of image quality. To obtain the same brightness, a larger amount of power would be required.

[0013] In addition, since the counter electrode is connected to all pixels, the light-emitting element functions as a large-capacity element. Therefore, a large amount of power is required to change the potential of the counter electrode.

[0014] In view of the above problems, an object of the present invention is to provide a display device that consumes low power and is bright. In addition, the pixel configuration and semiconductor device have little deviation from the brightness specified by the data potential. The present invention aims to provide a display device and a display apparatus. However, the present invention is based on the current value caused by the variation in the threshold voltage of the transistor. The objective is to suppress the variation in the [Means for solving the problem]

[0015] One aspect of the present invention is a power supply circuit including a transistor for controlling a current value supplied to a load, a first storage capacitor, A pixel including a second storage capacitor and first to fourth switches, After the threshold voltage of the transistor is held in the storage capacitor, a potential corresponding to the video signal is applied. In this way, the second storage capacitor is supplied with the threshold voltage. The potential corresponding to the video signal is added to the first storage capacitor and the potential obtained by dividing the potential by the capacitance. By maintaining the voltage, the current value variation caused by the variation in the threshold voltage of the transistor is reduced. This makes it possible to supply a desired current to a load such as a light emitting element. In addition, a display device that has little deviation from the luminance specified by a video signal can be provided. This makes it possible to

[0016] One aspect of the present invention is a semiconductor device including a transistor, a storage capacitor, a first switch, a second switch, and a third switch and a fourth switch, and One of the gate electrodes is electrically connected to the pixel electrode, and the source electrode and the drain electrode of the transistor are The other of the transistor electrodes is electrically connected to the first wiring via the second switch. The other of the source electrode and the drain electrode of the transistor is connected to the third switch. The gate electrode of the transistor is electrically connected to the storage capacitor. and electrically connected to the second wiring via the fourth switch, The port electrode is electrically connected to a third wiring via the storage capacitor and the first switch. It is a semiconductor device that is

[0017] One aspect of the present invention is a transistor, a first storage capacitor, a second storage capacitor, and a first switch. a first switch, a second switch, a third switch, and a fourth switch, One of the source electrode and the drain electrode of the transistor is electrically connected to the pixel electrode. One of the source electrode and the drain electrode of the transistor is connected to the second storage capacitor. and a source electrode and a drain electrode of the transistor. The first wiring is electrically connected to the second switch, and the second wiring is electrically connected to the second switch. The other of the source electrode and the drain electrode is connected to the gate of the transistor via the third switch. a gate electrode of the transistor electrically connected to the first storage capacitor and The fourth switch is electrically connected to the second wiring, and the gate of the transistor The electrode is electrically connected to a third wiring via the first storage capacitor and the first switch. This is a semiconductor device.

[0018] One aspect of the present invention is a transistor, a first storage capacitor, a second storage capacitor, and a first switch. a first switch, a second switch, a third switch, a fourth switch, and a fifth switch; One of the source electrode and the drain electrode of the transistor is electrically connected to the pixel electrode. One of the source electrode and the drain electrode of the transistor is connected to the second storage capacitor. and electrically connected to the gate electrode of the transistor, and One of the drain electrodes is electrically connected to a fourth wiring via a fifth switch, The other of the source electrode and the drain electrode of the transistor is connected to the first line through the second switch. the other of the source electrode and the drain electrode of the transistor is electrically connected to the line. The transistor is electrically connected to the gate electrode of the transistor through the third switch. The gate electrode of the transistor is connected to the second wiring via the first storage capacitor and the fourth switch. The gate electrode of the transistor is electrically connected to the first storage capacitor and the first The semiconductor device is electrically connected to the third wiring via the switch.

[0019] In the above configuration, the second wiring is the same as the wiring that controls the first switch. The second wiring may be connected to the first switch to the second switch in the previous row or the next row. It may be any of the scan lines that control the four switches.

[0020] One aspect of the present invention is a transistor, a first storage capacitor, a second storage capacitor, and a first switch. a first switch, a second switch, a third switch, and a fourth switch, One of the source electrode and the drain electrode of the transistor is electrically connected to the pixel electrode. One of the source electrode and the drain electrode of the transistor is connected to the second storage capacitor. and a source electrode and a drain electrode of the transistor. The first wiring is electrically connected to the second switch, and the second wiring is electrically connected to the second switch. The other of the source electrode and the drain electrode is connected to the gate of the transistor via the third switch. a gate electrode of the transistor electrically connected to the first storage capacitor and The gate of the transistor is electrically connected to the first wiring through the fourth switch. The port electrode is electrically connected to the third wiring via the first storage capacitor and the first switch. The semiconductor device is connected to the

[0021] One aspect of the present invention is a transistor, a first storage capacitor, a second storage capacitor, and a first switch. a second switch, a third switch, and a rectifying element; One of the source electrode and the drain electrode of the transistor is electrically connected to the pixel electrode. One of the source electrode and the drain electrode is connected to the gate of the transistor via the second storage capacitor. the other of the source electrode and the drain electrode of the transistor is electrically connected to the front The second switch is electrically connected to the first wiring, and the source voltage of the transistor is The other of the electrode and drain electrode is connected to the gate electrode of the transistor via the third switch. and a gate electrode of the transistor is electrically connected to the first storage capacitor and the rectifying capacitor. The gate electrode of the transistor is electrically connected to the second wiring through the current element. A semiconductor device electrically connected to a third wiring via a first storage capacitor and the first switch. It is a conductor device.

[0022] One aspect of the present invention is a transistor, a first storage capacitor, a second storage capacitor, and a first switch. a first switch, a second switch, a third switch, and a fourth switch, One of the source electrode and the drain electrode of the transistor is electrically connected to the pixel electrode. One of the source electrode and the drain electrode of the transistor is connected to the second storage capacitor. and a source electrode and a drain electrode of the transistor. The first wiring is electrically connected to the second switch, and the second wiring is electrically connected to the second switch. The other of the source electrode and the drain electrode is connected to the gate of the transistor via the third switch. a gate electrode of the transistor electrically connected to the first storage capacitor and The fourth switch is electrically connected to the third wiring via the first switch. electrically connected in parallel with the first storage capacitor and The semiconductor device is electrically connected to the wiring of 3.

[0023] The transistor may be an N-channel transistor. The semiconductor layer of the transistor may be made of an amorphous semiconductor film. The semiconductor layer of the transistor may be made of amorphous silicon.

[0024] The semiconductor layer of the transistor may be made of a crystalline semiconductor film. stomach.

[0025] In the above invention, the potential of the first wiring is set to the potential of the pixel electrode. The threshold voltage may be higher than the sum of the threshold voltages of the first and second transistors.

[0026] The transistor may be a P-channel transistor. In the invention, the potential of the first wiring is changed from the potential of the pixel electrode to the potential of the transistor. It may be characterized in that the value is lower than the value obtained by subtracting the threshold voltage.

[0027] One aspect of the present invention is a first storage capacitor, and one of the source electrode and the drain electrode is electrically connected to a load. the other of the source electrode and the drain electrode is electrically connected to the first wiring, and the gate a transistor whose gate electrode is electrically connected to the second wiring via the first storage capacitor; a second holding capacitor for holding a gate-source voltage of the transistor; and a first holding capacitor. a means for holding a first voltage in the second storage capacitor and a means for holding a second voltage in the second storage capacitor; means for discharging a second voltage of the capacitor to a threshold voltage of the transistor; A potential corresponding to a video signal is input to the first storage capacitor from the wiring. and a means for supplying a current set in the transistor to the load. It is a device.

[0028] The transistor may be an N-channel transistor. The semiconductor layer of the transistor may be made of an amorphous semiconductor film. The semiconductor layer of the transistor may be made of amorphous silicon.

[0029] The semiconductor layer of the transistor may be made of a crystalline semiconductor film. stomach.

[0030] The transistor may be a P-channel transistor.

[0031] Another aspect of the present invention is a display device having the semiconductor device described above. The electronic device has a display device.

[0032] The switches described in the specification can be of various types. For example, There are electrical switches and mechanical switches, i.e., switches that can control the flow of electric current. For example, a transistor (e.g., bipolar transistors, MOS transistors, etc.), diodes (e.g., PN Diodes, PIN diodes, Schottky diodes, MIM (Metal Ins Insulator Metal) diode, MIS (Metal Insulator Semiconductor) diodes, diode-connected transistors, etc.), Also, logic circuits that combine these can be used as switches. It is also possible to use

[0033] When a transistor is used as a switch, the transistor acts as a simple switch. However, the polarity (conductivity type) of the transistor is not particularly limited. It is desirable to use a transistor with a polarity that is smaller than the off-state current. The transistors include transistors with LDD regions and transistors with multi-gate structures. In addition, the potential of the source electrode of the transistor that operates as a switch is low. If the device is operating close to the power supply (Vss, GND, 0V, etc.), use an N-channel type. When the source electrode potential is close to the high-potential power supply (Vdd, etc.), the P-channel It is desirable to use a gate-source transistor. Since the absolute value of the voltage between the gates can be increased, the operation as a switch becomes easier. Since the source follower operation is less likely to occur, the output voltage is smaller. This can be prevented.

[0034] In addition, both N-channel and P-channel transistors are used to An S-type switch can be used as the switch. If a CMOS type switch is used, various Since the output voltage can be easily controlled relative to the input voltage, appropriate operation can be achieved. The voltage amplitude of the signal used to turn the switch on and off can be reduced, reducing power consumption. It is also possible to reduce power consumption.

[0035] When a transistor is used as a switch, one of the source electrode and the drain electrode is the input terminal of the switch, the other of the source electrode and drain electrode is the output terminal, The terminals of the diodes function as switches. When using a mode, the switch may not have a terminal for controlling conduction. Therefore, using a diode as a switch rather than a transistor is easier than using a wiring to control the terminal. Since no wires are required, the number of wires can be reduced.

[0036] In the present invention, being connected is synonymous with being electrically connected. Therefore, in the configuration disclosed in the present invention, a predetermined connection relationship, for example, in a drawing or a sentence, In addition to the connections shown, other elements (e.g., switches) that allow electrical connections between them may be included. The circuit is composed of a number of elements (such as switches, transistors, capacitance elements, inductors, resistance elements, and diodes). Of course, they may be arranged without any other elements in between, and may be electrically connected. "Connected" includes "directly connected." The load is not limited to a light-emitting element such as an electroluminescent element, and may be any element that allows current to flow. It is possible to apply a display medium that changes brightness, color tone, polarization, etc. by changing the light source. In addition, it is sufficient to supply a desired current to the load, so the load may be, for example, an electron-emitting element. element, liquid crystal element, electronic ink, electrophoretic element, grating light valve (GLV), Magnetic display such as plasma display (PDP) and digital micromirror device (DMD) It is also possible to use a display medium in which the contrast changes depending on the effect. It is also possible to use carbon nanotubes in the EL element. EL displays are used as display devices, and field emitters are used as display devices using electron-emitting elements. Mission Display (FED) and SED type flat panel display (SED:Surf ace-conduction Electron-emitter Disply) Examples of display devices using liquid crystal elements include liquid crystal displays, transmission liquid crystal displays, etc. LCDs, transflective LCDs and reflective LCDs are using electronic ink. The display device used is electronic paper.

[0037] A transistor is a semiconductor device that includes at least a gate electrode, a drain region, and a source region. Both are elements having three terminals, and a channel forming region is formed between the drain region and the source region. Here, the source region and the drain region are determined depending on the structure and operating conditions of the transistor. This makes it difficult to precisely define the extent of the source or drain regions. Therefore, when explaining the connection relationship of a transistor, For two terminals, one of the electrodes connected to these regions is called the first electrode, and the other is called the second electrode. and will be used in the explanation.

[0038] The transistor has at least three terminals including a base, an emitter, and a collector. The element may have one of the emitter and collector as the first electrode and the other as the second electrode. This corresponds to electrode 2.

[0039] In the present invention, various types of transistors can be applied. There is no particular limitation on the type. For example, amorphous silicon, polycrystalline silicon, microcrystalline (microcrystalline) silicon, A non-single-crystal semiconductor film, such as silicon (also called crystalline or semi-amorphous), When using a TFT, various For example, it can be manufactured at a lower temperature than single crystal silicon, It is possible to reduce manufacturing costs and increase the size of manufacturing equipment. This allows manufacturing on a large substrate and manufacturing a large number of display devices at the same time. Furthermore, it can be manufactured at low cost. Also, since the manufacturing temperature is low, the heat resistance is poor. A substrate may be used. For example, a transistor may be formed on a light-transmitting substrate such as a glass substrate. It can be manufactured.

[0040] When manufacturing polycrystalline silicon, the crystallinity is improved by using a catalyst (nickel, etc.). This further improves the electrical characteristics of the transistors, making it possible to manufacture transistors with excellent electrical characteristics. , gate driver circuits (scanning line driver circuits), source driver circuits (signal line driver circuits), Signal processing circuits (signal generation circuits, gamma correction circuits, DA conversion circuits, etc.) are integrated on the board. It is not always necessary to use a catalyst.

[0041] In addition, even when microcrystalline silicon is used, the gate driver circuit (scanning line driver circuit) and Part of the switch driver circuit (such as an analog switch) can be integrally formed on the substrate.

[0042] Furthermore, a transistor can be formed using a semiconductor substrate, an SOI substrate, or the like. In this case, MOS transistors, junction transistors, bipolar transistors, etc. These can be used as transistors. Therefore, it is possible to manufacture a transistor with low capacitance and high current supply capacity. This allows for lower power consumption and higher circuit integration.

[0043] In addition, ZnO, a-InGaZnO, SiGe, GaAs, IZO, ITO, SnO, etc. Transistors having any compound semiconductor or oxide semiconductor, and further, A thin film transistor made of a conductor or oxide semiconductor can be used. These allow the manufacturing temperature to be lowered, making it possible to manufacture transistors at room temperature, for example. As a result, transistors are directly mounted on substrates with low heat resistance, such as plastic substrates or film substrates. These compound semiconductors or oxide semiconductors can be used as transistors. It can be used not only for the channel part of a transistor, but also for other purposes. For example, these compound semiconductors or oxide semiconductors can be used as resistor elements, pixel electrodes, and transparent electrodes. Furthermore, since these can be formed or deposited simultaneously with the transistor, Costs can be reduced.

[0044] In addition, a transistor formed by inkjet or printing can also be used. This allows fabrication at room temperature, in a low vacuum, or on a large substrate. In addition, since it is possible to manufacture without using a mask (reticle), the transistor The layout can be easily changed. Furthermore, since there is no need to use resist, The number of processes can be reduced, and manufacturing costs can be reduced. Therefore, compared to etching after forming a film on the entire surface, no material is wasted and it can be produced at low cost. It becomes possible to manufacture

[0045] Also, transistors having organic semiconductors or carbon nanotubes can be used. Such transistors can be mounted on flexible substrates, allowing for collision-free operation. Not limited to these, various other transistors can be used. .

[0046] It should be noted that various types of substrates on which transistors are formed may be used. The substrate on which the transistor is formed can be any of the following: For example, single crystal substrates, SOI substrates, glass substrates, quartz substrates, plastic substrates, paper substrates, Cellophane substrate, stone substrate, wood substrate, cloth substrate (natural fibers (silk, cotton, linen), synthetic fibers (na Iron, polyurethane, polyester) or regenerated fiber (acetate, cupro, (including recycled polyester, etc.), rubber substrate, stainless steel substrate, stainless steel A substrate with a glass or steel foil can also be used. Then, the transistor is transferred to another substrate. The substrate on which the transistor is transferred may be a single crystal substrate, an SOI substrate, a glass substrate, or the like. Glass substrate, quartz substrate, plastic substrate, paper substrate, cellophane substrate, stone substrate, wood substrate Board, fabric substrate (natural fibers (silk, cotton, linen), synthetic fibers (nylon, polyurethane, polyester) containing recycled fibers (acetate, cupra, rayon, recycled polyester) (including leather substrate, rubber substrate, stainless steel substrate, stainless steel foil) By using such a substrate, it is possible to obtain a substrate with higher characteristics. It is possible to form a transistor, improve heat resistance, and reduce weight.

[0047] The structure of the transistor can take various forms and is not limited to a specific structure. For example, a multi-gate structure having two or more gate electrodes may be used. In this structure, the channel regions are connected in series, so multiple transistors are connected in series. This multi-gate structure reduces the off-state current and The improved breakdown voltage of the transistor can improve the reliability of the transistor. The multi-gate structure allows the drain to remain constant even when the drain-source voltage changes during operation in the saturation region. The drain-source current does not change much, and a flat voltage-current characteristic can be obtained. By using a voltage-current characteristic with a flat slope, it is possible to create an ideal current source circuit or a very It is possible to realize an active load with a high resistance value. As a result, it is possible to realize a differential circuit or capacitor with good characteristics. A current mirror circuit can be realized. In addition, gate electrodes are arranged above and below the channel region. The structure may be such that gate electrodes are placed above and below the channel region. This increases the effective channel area, which increases the amount of current and makes it easier for a depletion layer to form, resulting in S When gate electrodes are disposed above and below the channel region, The configuration is such that a plurality of transistors are connected in parallel.

[0048] Alternatively, a gate electrode may be disposed on the channel region. Alternatively, a staggered structure or an inverted staggered structure may be used. The channel region may be divided into a plurality of regions, or the channel region may be arranged in parallel. The transistors may be connected in a row or in series. The source electrode and the drain electrode may overlap. By using a structure in which the source electrode and drain electrode overlap with a part of the channel region, This prevents charge from accumulating in the LDD region, which can cause instability in operation. By providing an LDD region, the off-current can be reduced and the breakdown voltage of the transistor can be improved. This can improve the reliability of the transistor. By providing this region, even if the drain-source voltage changes when operating in the saturation region, To obtain a voltage-current characteristic in which the drain-source current does not change much and the slope is flat. can be done.

[0049] As described above, the transistors in the present invention include various types of transistors. can be used and can be formed on a variety of substrates. All of the circuits required to realize the above functions may be formed on the same substrate. For example, all the circuits required to realize a specific function are made on glass or plastic substrates. The semiconductor device may be formed on a single crystal substrate or an SOI substrate. All of the circuits required to realize this are formed on the same board, reducing the number of parts. It is possible to reduce costs and improve reliability by reducing the number of connections to circuit components. On the other hand, some of the circuits required to realize a given function are placed on a certain board, and Another part of the circuitry required to perform a predetermined function may be formed on another substrate. It is not necessary for all of the circuitry required to realize this to be formed on the same substrate.

[0050] For example, part of the circuitry required to achieve a specific function is placed on a glass substrate, and another part is placed on a glass substrate. The transistors are formed on a single crystal substrate, and an IC chip consisting of such transistors on a single crystal substrate is produced. The chip is connected to the glass substrate by COG (Chip On Glass) and placed on the glass substrate. Alternatively, the IC chip may be mounted on a TAB (Tape Automated Board) It is also possible to connect the glass substrate using a wiring board or a printed circuit board. Since some parts are formed on the same board, the number of parts can be reduced, resulting in cost reduction and circuit The number of connections to components can be reduced, improving reliability. Since circuits in parts with high drive frequencies and parts with high power consumption consume a lot of power, the circuits in these parts are By using an IC chip formed on a single crystal substrate, for example, rather than forming it on the same substrate as the circuit, An increase in power consumption can be prevented. In this specification, one pixel refers to one element whose brightness can be controlled. As an example, one pixel represents one color element, and the brightness is expressed by that one color element. Therefore, in this case, the color display device consisting of the color elements R (red), G (green), and B (blue) In this case, the smallest unit of an image is composed of three pixels: an R pixel, a G pixel, and a B pixel. The color elements are not limited to three colors, and more than three colors may be used, or colors other than RGB may be used. Other colors may be used. For example, RGBW (W is white) or RGB plus, for example, yellow, shear Some colors include magenta, emerald green, and vermilion. , RGB, a color similar to at least one color in RGB may be added to RGB. G, B1, and B2 are also acceptable. B1 and B2 are both blue, but have slightly different frequencies. Similarly, it may be R1, R2, G, B or R, G1, G2, B. By using color elements, it is possible to display more realistic images. By using color elements, power consumption can be reduced. When controlling brightness using multiple areas for one color element, use one area at a time. For example, when area gradation is performed or when sub-pixels are provided, In such a case, the area for controlling the brightness of one color element is There are multiple areas, and the gradation is expressed as a whole, but each area that controls the brightness is individually It may be a pixel, in which case one color element is made up of multiple pixels. Even if there are multiple areas that control brightness within one color element, they can be grouped together to form a single color. An element may be one pixel. In that case, one color element constitutes one pixel. In addition, when controlling the brightness of one color element using multiple areas, The size of the area that contributes to the display may differ depending on the color element. There are several brightness control areas for each, and the signal supplied to each area is slightly different. In other words, a plurality of color elements may be used for one color element to widen the viewing angle. By making the potential of the pixel electrodes in the respective areas different, the voltage applied to the liquid crystal molecules can be made different. This can also improve the viewing angle.

[0051] In this specification, a semiconductor device refers to a semiconductor element (such as a transistor or a diode). It also refers to all devices that can function by utilizing the properties of semiconductors. A display device may be a device that includes a plurality of pixels on a substrate, including a load, and a device that drives the pixels. Not only the display panel body with peripheral driving circuits formed, but also the flexible print This includes those with flexible printed circuit (FPC) or printed wiring board (PWB) attached.

[0052] In the present invention, the term "formed on a certain object" refers to a material that is formed on a certain object. In other words, the phrase "on top of" or "on top of" refers to something directly on top of something. It is not limited to being in contact with the object. It can also be when there is no direct contact, i.e., when there is no other object in between. Therefore, for example, if layer B is on top of layer A (or on top of layer A), When we say "formed," we mean the case where layer B is formed directly on top of layer A, or the case where layer A is formed on top of layer B. On top of that, another layer (such as layer C or layer D) is formed, and layer B is formed on top of that. The same applies to the phrase "above ~" and This is not limited to being directly on top of an object, but also includes cases where there is another object sandwiched between them. Therefore, for example, if layer B is formed above layer A, then Layer B may be formed directly on layer A, or another layer (such as layer C or layer D) may be formed on top of layer A. This also includes the case where a layer B is formed on the layer B. Similarly, when it says "or below ~," it can be used to refer to directly adjacent or adjacent This includes cases where there is no [Effects of the Invention]

[0053] The present invention reduces variations in current values ​​due to variations in the threshold voltage of transistors. Therefore, it is possible to supply a desired current to a load such as a light emitting element. In particular, when a light emitting element is used as a load, the luminance is uniform within one frame. It is possible to provide a display device in which the ratio of the light emitting period to the room period is high. [Brief explanation of the drawings]

[0054] [Figure 1] 1A to 1C illustrate a pixel configuration described in Embodiment 1. [Figure 2] 2 is a timing chart illustrating the operation of the pixel shown in FIG. 1; [Figure 3] 2A to 2C are diagrams for explaining the operation of the pixel shown in FIG. 1; [Figure 4] Model diagram of voltage-current characteristics due to channel length modulation. [Figure 5] 1A to 1C illustrate a pixel configuration described in Embodiment 1. [Figure 6] 1A to 1C illustrate a pixel configuration described in Embodiment 1. [Figure 7] 1A to 1C illustrate a display device described in Embodiment 1. [Figure 8] 1A to 1C illustrate a writing operation of the display device shown in Embodiment 1. [Figure 9] 1A to 1C illustrate a pixel configuration described in Embodiment 2. [Figure 10] 10A to 10C illustrate a pixel configuration described in Embodiment 3. [Figure 11] 10A to 10C illustrate a pixel configuration described in Embodiment 3. [Figure 12] 10A to 10C illustrate a pixel configuration described in Embodiment 3. [Figure 13] 10A to 10C illustrate a pixel configuration described in Embodiment 4. [Figure 14] 10A to 10C illustrate a pixel configuration described in Embodiment 4. [Figure 15] 10A to 10C illustrate a pixel configuration described in Embodiment 4. [Figure 16] 10A to 10C illustrate a pixel configuration described in Embodiment 4. [Figure 17] FIG. 13 is a partial cross-sectional view of a pixel shown in Embodiment 9. [Figure 18] 10A to 10C illustrate a light-emitting element described in Embodiment 9. [Figure 19] 13A and 13B are diagrams illustrating a light extraction direction shown in Embodiment 9. [Figure 20] FIG. 13 is a partial cross-sectional view of a pixel shown in Embodiment 9. [Figure 21] FIG. 13 is a partial cross-sectional view of a pixel shown in Embodiment 9. [Figure 22] FIG. 13 is a partial cross-sectional view of a pixel shown in Embodiment 9. [Figure 23] FIG. 13 is a partial cross-sectional view of a pixel shown in Embodiment 9. [Figure 24] FIG. 13 is a partial cross-sectional view of a pixel shown in Embodiment 9. [Figure 25] 12A to 12C illustrate a display device described in Embodiment 11. [Figure 26] 12A to 12C illustrate a display device described in Embodiment 11. [Figure 27] 12A to 12C illustrate a display device described in Embodiment 11. [Figure 28] FIG. 22 is a partial cross-sectional view of a pixel shown in Embodiment 11. [Figure 29] 10A to 10C illustrate a pixel configuration described in Embodiment 5. [Figure 30] 10A to 10C illustrate a pixel configuration described in Embodiment 5. [Figure 31] 10A to 10C illustrate a pixel configuration described in Embodiment 6. [Figure 32] 32 is a timing chart illustrating the operation of the pixel shown in FIG. 31. [Figure 33] 1A to 1C are diagrams illustrating electronic devices to which the present invention can be applied. [Figure 34] FIG. 1 is a diagram showing an example of the configuration of a mobile phone. [Figure 35] FIG. 1 is a diagram showing an example of an EL module. [Figure 36] FIG. 1 is a block diagram showing the main components of an EL television receiver. [Figure 37] 10A to 10C illustrate a pixel configuration described in Embodiment 6. [Figure 38] 10A to 10C illustrate a pixel configuration described in Embodiment 7. [Figure 39] FIG. 10 is a diagram illustrating a driving method that combines a digital gray scale method and a time gray scale method. [Figure 40] 10A to 10C illustrate a pixel configuration described in Embodiment 7. [Figure 41] 10A to 10C illustrate a pixel configuration described in Embodiment 7. [Figure 42] 10A to 10C illustrate a pixel configuration described in Embodiment 7. [Figure 43] 1A to 1C illustrate a pixel configuration described in Embodiment 1. [Figure 44] FIG. 7 is a top view illustrating the layout of the pixel shown in FIG. 6. [Figure 45] FIG. 7 is a top view illustrating the layout of the pixel shown in FIG. 6. [Figure 46] 10A to 10C illustrate a pixel configuration described in Embodiment 8. [Figure 47] 47 is a timing chart illustrating the operation of the pixel shown in FIG. 46. [Figure 48] FIG. 47 is a diagram for explaining the operation of the pixel shown in FIG. 46. [Figure 49] 10A to 10C illustrate a pixel configuration described in Embodiment 8. [Figure 50] 10A to 10C illustrate a pixel configuration described in Embodiment 8. [Figure 51] 13A to 13C illustrate a light-emitting element described in Embodiment 10. [Figure 52] 13A to 13C illustrate a light-emitting element described in Embodiment 10. [Figure 53] 1A to 1C illustrate the operation of the pixel described in Embodiment 1. [Figure 54] 1A to 1C illustrate a pixel configuration described in Embodiment 1. [Figure 55] 1A to 1C illustrate a pixel configuration described in Embodiment 1. [Figure 56] 1A to 1C are diagrams illustrating application examples of a display device according to the present invention. [Figure 57] 1A to 1C are diagrams illustrating application examples of a display device according to the present invention. [Figure 58] 1A to 1C are diagrams illustrating application examples of a display device according to the present invention. [Figure 59] 1A to 1C are diagrams illustrating application examples of a display device according to the present invention. [Figure 60] 1A to 1C are diagrams illustrating application examples of a display device according to the present invention. [Figure 61] 1A to 1C are diagrams illustrating application examples of a display device according to the present invention. [Figure 62] FIG. 1 is a diagram illustrating a pixel configuration according to a conventional technique. [Figure 63] FIG. 1 is a diagram illustrating a pixel configuration according to a conventional technique. [Figure 64] 1 is a timing chart for operating a pixel according to the prior art; [Figure 65] FIG. 10 is a diagram illustrating the ratio of a light emitting period to one frame period when using conventional technology. DETAILED DESCRIPTION OF THE INVENTION

[0055] The present invention will be described in one embodiment below, although the present invention can be embodied in many different embodiments. and modifications in form and detail are possible without departing from the spirit and scope of the present invention. It will be readily understood by those skilled in the art that various modifications can be made. It should be noted that in the configuration of the present invention described below, The reference numerals denoting the above are commonly used in different drawings. (Embodiment 1) The basic structure of the pixel of the present invention will be described with reference to FIG. 1. The pixel shown in FIG. a register 110, a first switch 111, a second switch 112, a third switch 113, A fourth switch 114, a first capacitance element 115, a second capacitance element 116, and a light-emitting element 117 The pixel has a signal line 118, a first scanning line 119, a second scanning line 120, a third scanning line 121, a fourth scanning line 122, a fifth scanning line 123, a sixth scanning line 124, a sixth scanning line 125, a sixth scanning line 126, a sixth scanning line 127, a sixth scanning line 128, a sixth scanning line 129, a sixth scanning line 130, a sixth scanning line 131, a sixth scanning line 132, a sixth scanning line 133, a sixth scanning line 134, a sixth scanning line 135, a sixth scanning line 136, a sixth scanning line 137, a sixth scanning line 138, a sixth scanning line 139, a sixth scanning line 139, a sixth scanning line 139, a sixth scanning line 140, a sixth scanning line 141, a sixth scanning line 142, a sixth scanning line 143, a 3, a scanning line 121, a power supply line 122, and a potential supply line 123. In the figure, the transistor 110 is an N-channel transistor, and When the voltage (Vgs) exceeds the threshold voltage (Vth), the transistor is in a conductive state. The pixel electrode of the light emitting element 117 functions as an anode, and the counter electrode 124 functions as a cathode. The gate-source voltage of a transistor is Vgs, the drain-source voltage is Vds, and the threshold The lower voltage is Vth, and the voltages stored in the first capacitance element 115 and the second capacitance element 116 are The power supply line 122, the potential supply line 123, and the signal line 118 are denoted as Vc1 and Vc2, respectively. These are also called the first wiring, the second wiring, and the third wiring, respectively. The second scanning line 120 and the third scanning line 121 are connected to the fourth wiring, the fifth wiring, and the sixth wiring, respectively. It can also be called wiring.

[0056] The first electrode (one of the source electrode and the drain electrode) of the transistor 110 is The second electrode (the other of the source electrode and the drain electrode) is connected to the pixel electrode of the second The gate electrode is connected to the power supply line 122 via the second switch 112, and the gate electrode is connected to the third switch 113. and is connected to the power supply line 122 via the second switch 112. The switch 113 is connected between the gate electrode of the transistor 110 and the second switch 112. are.

[0057] The connection point between the gate electrode of the transistor 110 and the third switch 113 is designated as a node 130, the node 130 is connected to the first capacitor 115 and the first switch 111. That is, the first electrode of the first capacitor 115 is connected to the first The second electrode is connected to the signal line 118 via the switch 111, and the second electrode is connected to the gate electrode of the transistor 110. The first electrode of the first capacitor 115 is connected to the fourth switch 114. The node 130 is also connected to the potential supply line 123 via the second capacitor element 1. 16 is also connected to the first electrode of the transistor 110. The first electrode of element 116 is connected to the gate electrode of transistor 110, and the second electrode is connected to the gate electrode of transistor 110. These capacitance elements are connected to the first electrode of the capacitor 110. It may be formed by sandwiching an insulating film between the transistors as shown in FIG. It is also possible to omit the second capacitance element 116 by using the gate capacitance of the transistor 110. The means for holding these voltages is called a storage capacitor. The second electrode of the capacitor 15 is connected to a wiring to which the first electrode of the second capacitor 116 is connected. The node 131 is connected to the first electrode of the transistor 110 and the second electrode of the second capacitor 116. The connection point between the electrode and the wiring that connects the pixel electrode of the light emitting element 117 is a node 132. , and the second electrode of the transistor 110, the second switch 112 and the third switch 11 The connection point with the wiring connecting the terminals 3 and 4 is designated as node 133.

[0058] In addition, when signals are input to the first scanning line 119, the second scanning line 120, and the third scanning line 121, As a result, the first switch 111, the second switch 112, and the third switch The on / off of the fourth switch 113 and the fourth switch 114 is controlled.

[0059] The signal line 118 is a signal corresponding to the gradation of the pixel, i.e., brightness data, which corresponds to a video signal. A potential corresponding to the voltage is input.

[0060] Next, the operation of the pixel shown in FIG. 1 will be explained using the timing chart of FIG. 2 and FIG. 3. In FIG. 2, one frame period, which corresponds to the period for displaying one screenful of image, is , which is divided into an initialization period, a threshold voltage writing period, a data writing period, and a light emitting period. The initialization period, threshold voltage write period, and data write period are all addressed together. There is no particular limit to the length of one frame period, but if the person viewing the image notices flickering, It is preferable to set the shutter speed to at least 1 / 60 seconds or less so that the shutter speed is not noticeable.

[0061] The counter electrode 124 of the light emitting element 117 is supplied with a potential V1 (V1: any number). In addition, the potential difference required for the light emitting element 117 to emit light is V EL Let's say And power line 122 has V1+V EL A potential of +Vth+α (α: any positive number) is input. In other words, the power supply line 122 is V1+V EL Any potential above +Vth+α is sufficient. The potential of the supply line 123 is not particularly limited, but it is within the range of the potential input to the panel on which the pixels are formed. This eliminates the need to fabricate a separate power supply. Here, the potential of the potential supply line 123 is set to V2.

[0062] First, as shown in FIG. 2(A) and FIG. 3(A), in the initialization period, the first switch 111 is turned off, and the second switch 112, the third switch 113, and the fourth switch 114 are turned on. At this time, the transistor 110 is in a conductive state, and the first capacitor 115 is V1+V EL +Vth+α-V2, and Vth+α is held in the second capacitance element 116. During the initialization period, a predetermined voltage is applied to the first capacitance element 115 and a predetermined voltage is applied to the second capacitance element 116. It is sufficient that 16 maintains a voltage higher than Vth.

[0063] During the threshold voltage writing period shown in FIG. 2(B) and FIG. 3(B), the second switch 11 Therefore, the potential of the first electrode, i.e., the source electrode, of the transistor 110 is The gate-source voltage Vgs of the transistor 110 rises above the threshold voltage (Vth ), the transistor 110 is turned off. The voltage Vc2 held at 16 is approximately Vth.

[0064] In the subsequent data write period shown in FIG. 2(C) and FIG. 3(C), the third switch After turning off the first switch 113 and the fourth switch 114, the first switch 111 is turned on. At this time, a potential (V2+Vdata) corresponding to the luminance data is input from the signal line 118. The voltage Vc2 held in the second capacitance element 116 is the voltage Vc1 held in the first capacitance element 115, the second capacitance element 116, and the If the capacitances of the capacitor 116 and the light emitting element 117 are C1, C2, and C3, respectively, then C3> >From C1 and C2, it can be expressed as equation (1).

[0065]

number

[0066] C1 and C2 are necessary when determining the potential to be supplied from the signal line 118. The relationship between these is not particularly limited. When C1>C2, Vdata The amplitude of C2 can be reduced, which reduces power consumption. In the case of C1, it is necessary to suppress the change in Vc2 due to the on / off and off current of surrounding switches. Due to these opposing effects, C1 and C2 are equal, and the first capacitance element 115 It is preferable that the first and second capacitance elements 116 have the same size.

[0067] If it is desired that the light emitting element 117 does not emit light in the next light emitting period, Vdata≦ Simply input a potential of 0.

[0068] Next, during the light emission period shown in FIG. 2(D) and FIG. 3(D), the first switch 111 is turned off. After that, the second switch 112 is turned on. At this time, the gate The source voltage is Vgs=Vth+Vdata×(C1 / (C1+C2)), and the brightness data A current corresponding to the input flows through the transistor 110 and the light emitting element 117, and the light emitting element 117 emits light. Of course, the potential corresponding to the brightness data input from the signal line 118 is applied to the transistor. The gate-source voltage of the capacitor 110 is Vgs=Vth+Vdata×(C1 / (C1+C2 )) and Vdata is determined taking this into consideration.

[0069] The current I flowing through the light emitting element 117 is the current I when the transistor 110 is operated in the saturation region. In this case, it is expressed by equation (2).

[0070]

number

[0071] When the transistor 110 is operated in the linear region, the current flowing through the light emitting element 117 is I is expressed by equation (3).

[0072]

number

[0073] where W is the channel width of the transistor 110, L is the channel length, μ is the mobility, and Cox refers to storage capacity.

[0074] From the formulas (2) and (3), it is possible to determine whether the operating region of the transistor 110 is a saturation region or a linear region. In either case, the current flowing through the light emitting element 117 is equal to or greater than the threshold voltage of the transistor 110. Therefore, the threshold voltage of the transistor 110 does not depend on the voltage (Vth). The variation in the current value caused by the difference is suppressed, and a current corresponding to the brightness data is supplied to the light emitting element 117. It is possible.

[0075] From the above, it is possible to determine whether the luminance variation caused by the variation in the threshold voltage of the transistor 110 is a problem. In addition, the potential of the opposing electrode is kept constant during operation, so power consumption is reduced. The force can be reduced.

[0076] Furthermore, when the transistor 110 is operated in the saturation region, the light emitting element 117 The deterioration of the light-emitting element can also be suppressed by reducing the variation in brightness due to the deterioration of its current-voltage characteristics. This is not limited to the case where the characteristic is shifted parallel to the curve before deterioration. When the differential value is expressed, it may be different from that before the deterioration. Then, V of the light emitting element 117 EL increases and the first electrode, i.e., the source, of transistor 110 At this time, the potential of the source electrode of the transistor 110 rises. The gate electrode of the transistor 110 is connected to the second electrode of the second capacitor 116. The gate electrode is connected to the SOI electrode, and the gate electrode side is in a floating state. As the source potential rises, the gate potential of the transistor 110 also rises by the same amount. Therefore, the Vgs of the transistor 110 does not change, and therefore, even if the light emitting element deteriorates, the transistor It does not affect the current flowing through the resistor 110 and the light emitting element 117. It can be seen that the current I flowing through the light emitting element does not depend on the source potential or the drain potential.

[0077] Therefore, when the transistor 110 is operated in the saturation region, The transistor 110 due to the variation in threshold voltage of the transistor 110 and the degradation of the light emitting element 117 This can suppress variations in the current flowing through the

[0078] When the transistor 110 is operated in the saturation region, the shorter the channel length L, the greater the drop. Due to the phenomenon of breakdown, if the drain voltage is increased significantly, a large amount of current tends to flow.

[0079] In addition, when the drain voltage is increased above the pinch-off voltage, the pinch-off point moves toward the source. However, the effective channel length that functions as a real channel decreases. This phenomenon is called channel length modulation. The pinch-off point is the point where the channel disappears. The pinch-off voltage is the boundary point where the channel thickness becomes 0 under the gate. This refers to the voltage when the pinch-off point becomes the drain end. This phenomenon also becomes more pronounced as the channel length L becomes shorter. For example, a model diagram of the voltage-current characteristics due to channel length modulation is shown in Figure 4. In FIG. 4, the channel lengths L of the transistors are in the order of (a)>(b)>(c).

[0080] From the above, when the transistor 110 is operated in the saturation region, the drain-source It is preferable that the current I with respect to the inter-gate voltage Vds is as constant as possible. For example, the channel length L of a transistor is It is preferable that the channel width W is larger than the channel length L. The channel length L is 10 μm or more and 50 μm or less. More preferably, the channel length L is 15 μm or more and 40 μm or less. The width W is not limited to this.

[0081] As described above, the variation in current value caused by the variation in threshold voltage of the transistor is suppressed. Therefore, in the present invention, the supply of the current controlled by the transistor can be The light-emitting element 117 shown in FIG. Applying a device (organic EL device, inorganic EL device, or EL device containing organic and inorganic materials) In addition, instead of the light emitting element 117, an electron emitting element, a liquid crystal element, electronic ink, etc. can be used. An example in which an EL element 517 is used as the light-emitting element 117 is shown in FIG. FIG. 5 shows a state in which a current flows from the pixel electrode 511 to the counter electrode 124.

[0082] The transistor 110 also has a function of controlling the current supplied to the light-emitting element 117. Therefore, the type of transistor is not particularly limited and various types can be used. For example, thin film transistors (TFTs) using crystalline semiconductor films, amorphous silicon and polycrystalline Thin film transistors using non-single crystal semiconductor films, such as silicon, semiconductor substrates, and SOI Transistors formed using a substrate, MOS transistors, junction transistors, barrier transistors Bipolar transistors, transistors using compound semiconductors such as ZnO and a-InGaZnO transistors, organic semiconductors, carbon nanotube transistors, and other transistors The transistor 110 may be applied to the

[0083] The first switch 111 supplies a potential corresponding to the luminance data, that is, a video signal, from the signal line 118. The timing of inputting the voltage to the pixel is selected, and the voltage held mainly in the first capacitor element 115, and The voltage held in the second capacitance element 116, i.e., the gate-source voltage of the transistor 110 The second switch 112 changes the second voltage of the transistor 110. The timing for supplying a predetermined potential to the electrode is selected. The second electrode of the first capacitor element 115 and the first electrode of the second capacitor element 116 are also supplied with the predetermined voltage. The third switch 113 connects the gate electrode of the transistor 110 to the second electrode The fourth switch 114 controls the connection between the first capacitor and the second capacitor for each frame period. The timing for holding a predetermined voltage in the element 115 is selected, and the first capacitance element 115 The first switch controls whether or not a predetermined potential is supplied to the electrode. 111, the second switch 112, the third switch 113, and the fourth switch 114 are There is no particular limitation as long as it has a function. For example, it may be a transistor or a diode. Alternatively, a logic circuit that combines these may be used. The fourth switch 112 and the fourth switch 114 apply a signal or a potential to the pixel at the above timing. In addition, the third switch 113 may also perform the above function. If possible, there is no particular need.

[0084] For example, in the initialization period and the threshold voltage writing period, A constant voltage can be maintained, and a signal according to the pixel gradation is written during the data writing period. When the pixel can be directly inputted, the first switch 111 and the fourth switch 112 are provided in the pixel. Furthermore, the pixel may be set to V1+V EL If it is possible to supply +Vth+α (α>0), the second switch can be used as shown in Figure 43. The pixel shown in FIG. 43 includes a transistor 110, a first The pixel electrode 4300 includes a capacitor 115, a third switch 113, and a pixel electrode 4300. The first electrode (one of the source electrode and the drain electrode) of the transistor 110 is connected to the pixel electrode 4300. The gate electrode is connected to the second electrode of the transistor 110 via the third switch 113. The gate electrode of the transistor 110 is connected to the first capacitor 115. The first electrode of the first capacitor 115 is also connected to the second electrode. The signal, that is, the potential according to the luminance data (that is, V2+Vdata) and the first capacitance element 1 An arbitrary potential (i.e., V2) is supplied to 15 for a predetermined period to maintain a predetermined voltage. Note that since the gate capacitance 4310 of the transistor 110 is used as a storage capacitance, In this case, it is not necessary to provide the second capacitor element 116 shown in FIG. In this case, desired potentials can be supplied to the respective electrodes in the same manner as in the timing chart shown in FIG. Therefore, the variation in the current value caused by the variation in the threshold voltage of the transistor 110 is suppressed. Therefore, a desired current can be supplied to the pixel electrode 4300. Of course, the second capacitance element 116 in FIG. It is possible to use it and omit it.

[0085] Next, in FIG. 6, the first switch 111, the second switch 112, the third switch 113, and The case where an N-channel transistor is used as the fourth switch 114 is shown. The same components as those in FIG. 1 are designated by the same reference numerals and will not be described further.

[0086] The first switching transistor 611 corresponds to the first switch 111 in FIG. The second switching transistor 612 corresponds to the second switch 112, and the third switch The switching transistor 613 corresponds to the third switch 113, and the fourth switching transistor The transistor 614 corresponds to the fourth switch 114. The length of the first switching transistor 611 and the second switching transistor 61 2. The third switching transistor 613 and the fourth switching transistor 614 It is preferable that the channel length is longer than the channel length of any of the transistors.

[0087] The first switching transistor 611 has a gate electrode connected to the first scanning line 119 and a The first electrode is connected to the signal line 118, and the second electrode is connected to the first electrode of the first capacitor element 115. do.

[0088] The gate electrode of the second switching transistor 612 is connected to the second scanning line 120. The first electrode is connected to the node 133 and the second electrode is connected to the power supply line 122. There are.

[0089] The third switching transistor 613 has a gate electrode connected to the third scanning line 121. , a first electrode is connected to node 130 and a second electrode is connected to node 133 .

[0090] The gate electrode of the fourth switching transistor 614 is connected to the third scanning line 121. The first electrode is connected to the first electrode of the first capacitor 115, and the second electrode is connected to a potential It is connected to the supply line 123.

[0091] Each switching transistor is turned on when the signal input to the corresponding scanning line is at H level. When the input signal is at L level, it is turned on, and when the input signal is at L level, it is turned off.

[0092] One form of the layout of the pixel shown in FIG. 6 is shown in FIG. 44 using a top view. The configurations of the resistors, capacitors, light emitting elements, etc. will be described in the following embodiments, so Only the layout will be described. The switching transistor 611 to the fourth switching transistor 614 are A bottom-gate transistor is used, in which the gate electrode is located below the body layer.

[0093] The conductive layer 4410 shown in FIG. 44 is connected to the first scanning line 119 and the first switching transistor. The conductive layer 4411 includes a portion that functions as a gate electrode of the first electrode 611, and the signal line 118 and the first electrode 611 are connected to each other. The first electrode of the switching transistor 611 is also included. The layer 4412 is a second electrode of the first switching transistor 611 and a first capacitor element. 115 and serves as a first electrode of the fourth switching transistor 614. The conductive layer 4413 includes a portion where the second electrode of the first capacitor 115 and the second capacitor The first electrode of the element 116 and the portion that functions as the gate electrode of the transistor 110 are included. The conductive layer 4413 is connected to the third switching transistor 4414 via a wiring 4414. The conductive layer 4415 includes a portion that functions as a first electrode of the conductive layer 613. 4416 is a second electrode of the second capacitor 116, a first electrode of the transistor 110, and It includes a portion that functions as a light emitting element, and is connected to the pixel electrode 4455 of the light emitting element through a contact. The conductive layer 4417 is connected to the second electrode of the transistor 110 and the third switching element. a second electrode of the second switching transistor 613 and a first electrode of the second switching transistor 612 The conductive layer 4418 includes a portion that functions as an electrode, and is connected to the power supply line 122 and the second switch. The conductive layer 4419 includes a portion that serves as a second electrode of the transistor 612. The scanning line 120 and the gate electrode of the second switching transistor 612 The conductive layer 4420 includes a gate electrode of the third switching transistor 613 and a , including a portion that functions as the gate electrode of the fourth switching transistor 614, The fourth switching transistor 4421 is connected to the third scanning line 121. The conductive layer 4422 including the portion that functions as the second electrode of the transistor 614 is connected to the wiring 4423. is connected to the potential supply line 123 via

[0094] Among the conductive layers, the gate electrode of the first switching transistor 611, The portions functioning as the first electrode and the second electrode are formed by the conductive layer and the semiconductor layer 4431, respectively. and the gate of the second switching transistor 612. The portions that function as the first electrode, the second electrode, and the conductive layer that includes each of them are made of a semiconductor. The third conductive layer 4432 is formed by overlapping with the conductive layer 4432. The gate electrode, the first electrode, and the second electrode of the switching transistor 613 are The portions overlapping the conductive layer and the semiconductor layer 4433 are shown. The gate electrode, the first electrode, and the second electrode of the fourth switching transistor 614 are connected to each other. The portions that function as the conductive layers are formed by overlapping the conductive layer and the semiconductor layer 4434. Similarly, in the transistor 110, the gate electrode, the first electrode, and The portion functioning as the second electrode overlaps the conductive layer and the semiconductor layer 4430. The first capacitor 115 is a conductive layer portion where the conductive layer 4412 is formed. The second capacitor 116 is formed by connecting the conductive layer 4413 and the conductive layer 4414 to each other. It is formed in the overlapping area of ​​4416.

[0095] In addition, the conductive layer 4410, the conductive layer 4413, the conductive layer 4419, the conductive layer 4420, the third running The scan line 121 and the potential supply line 123 can be made of the same material and in the same layer. A semiconductor layer 4430, a semiconductor layer 4431, a semiconductor layer 4432, a semiconductor layer 4433, and a semiconductor The conductive layer 4434, the conductive layer 4411, the conductive layer 4412, the conductive layer 4415, the conductive layer 4416, The conductive layer 4417, the conductive layer 4418, and the conductive layer 4422 are each made of the same material and layer. In addition, the wiring 4 can be fabricated using the same material and the same layer as the pixel electrode 4455. 414, wiring 4421, and wiring 4423 can be fabricated.

[0096] As shown in FIG. 44, each transistor except for the first switching transistor 611 In the case of a capacitor, one of the source electrode and the drain electrode is structured to surround the other electrode. This allows the channel width to be increased. This is particularly effective when an amorphous semiconductor layer having a lower mobility than a crystalline semiconductor layer is used as the semiconductor layer. Of course, the first switching transistor 611 also has a source electrode and a drain electrode. A structure in which one electrode encloses the other electrode may also be used.

[0097] Next, a layout form different from that shown in FIG. 44 of the pixel shown in FIG. 6 will be shown in FIG. 4 using a top view. 5. The transistor 110 and the first switching transistor shown in FIG. The fourth switching transistor 611 to the fourth switching transistor 614 have gate electrodes positioned on the semiconductor layers. The transistors used are top-gate transistors such as staggered type.

[0098] In FIG. 45, the conductive layer 4510 is connected to the first scanning line 119 and the first switching transistor. The conductive layer 4511 includes a portion that functions as a gate electrode of the transistor 611, and is connected to the signal line 118. It includes a portion that functions as the first electrode of the first switching transistor 611. The film 4520 serves as a semiconductor layer and a second electrode of the first switching transistor 611. The part that functions as the first electrode and semiconductor layer of the fourth switching transistor 614 The semiconductor device 110 includes a portion that functions as a first electrode of the first capacitor 115. The conductive film 4520 is connected to the potential supply line 123 via the wiring 4512, and the wiring 451 2 serves as the second electrode of the fourth switching transistor 614. 4513 denotes a second electrode of the first capacitor 115 and a first electrode of the second capacitor 116. and a portion which functions as the gate electrode of the transistor 110. The third switching transistor 613 is connected to the first electrode 4514 via the wiring 4514. This semiconductor film 4521 is connected to the third switching transistor. The semiconductor layer of the transistor 613 and the portion that functions as the second electrode, the second switching transistor, The portion that functions as the first electrode and the semiconductor layer of the transistor 612, The first electrode, the semiconductor, the portion functioning as the second electrode, and the second capacitor element 116 The conductive layer 4515 includes a portion that functions as a second electrode. The conductive layer 4 includes a portion that functions as the gate electrode of the switching transistor 612 of the second conductive layer 4. 516 is a power supply line 122 and a second electrode of the second switching transistor 612. The conductive layer 4517 includes the gate of the third switching transistor 613. a portion that functions as a gate electrode of the fourth switching transistor 614; The wiring 4518 is connected to the third scanning line 121 . The pixel electrode 4545 of the light-emitting element is connected to the semiconductor film 4521 through a wiring 4519. are.

[0099] Note that in the first capacitor 115, the semiconductor film 4520 and the conductive layer 4513 overlap each other. The second capacitor 116 has a portion where the semiconductor film 4521 and the conductive layer 4513 overlap each other. It is formed in minutes.

[0100] In addition, the conductive layer 4510, the conductive layer 4513, the conductive layer 4515, the conductive layer 4517, the third running The scan line 121 and the potential supply line 123 can be made of the same material and in the same layer. The semiconductor film 4520 and the semiconductor film 4521 can be manufactured using the same material and the same layer. In addition, the same material and layer as the conductive layer 4511 are used to form a wiring 4512, a wiring 4514, and a conductive layer 4515. An electrical layer 4516 and a wiring 4518 can be formed.

[0101] The pixel layout is not limited to the above.

[0102] In the pixel configuration of FIG. 6, the threshold voltage of the transistor 110 is controlled by the same operation method as in FIG. Therefore, the variation in the current value caused by the variation in the voltage can be suppressed. A current corresponding to the data can be supplied to the light emitting element 117, and the variation in brightness can be suppressed. Furthermore, when the transistor 110 is operated in the saturation region, It is also possible to suppress variations in luminance due to deterioration of the light emitting elements 117.

[0103] In addition, pixels can be constructed using only N-channel transistors, which simplifies the manufacturing process. In addition, the semiconductor layer of the transistor that constitutes the pixel may be made of an amorphous semiconductor. Conductors, semi-amorphous semiconductors, etc. can be used. For example, amorphous semiconductors The use of these semiconductors allows This allows for the simplification of the manufacturing process, which in turn reduces manufacturing costs and improves yield. Improvements can be made.

[0104] The first switching transistor 611 and the second switching transistor 61 2. The third switching transistor 613 and the fourth switching transistor 614 Since the transistor operates as a simple switch, the polarity (conductivity type) of the transistor is not particularly limited. However, it is preferable to use a transistor with low off-state current. The transistors that do not have this feature are those that have an LDD region or a multi-gate structure. Also, there are CMOS type switches that use both N-channel and P-channel types. It can also be switched to

[0105] Also, as long as the operation is the same as that shown in Figure 1, the switch connections can take various configurations. As can be seen from FIG. 3, which explains the operation of the pixel configuration of FIG. 1, In the present invention, the initialization period, threshold voltage writing period, data writing period, and light emitting period are , it is sufficient if the conduction is as shown by the solid lines in Figures 53(A) to 53(D). Any configuration may be used as long as switches and the like are arranged and operated so as to satisfy this requirement.

[0106] During the initialization period, a predetermined voltage is applied to the first capacitance element 115 and a predetermined voltage is applied to the second capacitance element 116. It is sufficient that a voltage higher than the threshold voltage Vth of the transistor 110 is maintained. Therefore, as shown in FIG. 54, the node 132 is connected to the potential supply line via a fifth switch 5405. The fifth switch 5405 may be connected to the first switch 5401. This fifth switch 5405 is turned on only during the initialization period. In FIG. 54, the scanning line that controls the on / off of the fifth switch 5405 is not shown. The potential of the potential supply line 5401 is V1+V EL A lower potential is better More preferably, the potential is equal to or lower than V1. By setting the potential to such a level, the light emitting element 117 Since a reverse bias voltage can be applied to the Deterioration of the light-emitting element can be suppressed, thereby extending the life of the light-emitting element. .

[0107] Next, a display device having the above-described pixel of the present invention will be described with reference to FIG.

[0108] The display device includes a signal line driver circuit 711, a scanning line driver circuit 712, and a pixel portion 713. The pixel section 713 is connected to a plurality of signal lines S arranged extending in the column direction from the signal line driving circuit 711. 1 to Sm and power supply lines P1_1 to Pm_1, which are arranged extending in the row direction from the scanning line driving circuit 712. A plurality of first scanning lines G1_1 to Gn_1, second scanning lines G1_2 to Gn_2, and a third scanning line G1_3 are arranged. The three scanning lines G1_3 to Gn_3, the potential supply lines P1_2 to Pn_2, and the signal lines S1 to Sn_3 are The pixel 714 is arranged in a matrix corresponding to the pixel Sm. 14 is a signal line Sj (one of the signal lines S1 to Sm), a power supply line Pj_1, a first running A scanning line Gi_1 (one of the scanning lines G1_1 to Gn_1), a second scanning line Gi_2, It is connected to the third scanning line Gi_3 and the potential supply line Pi_2.

[0109] The signal line Sj, the power supply line Pj_1, the first scanning line Gi_1, the second scanning line Gi_2, The third scanning line Gi_3 and the potential supply line Pi_2 correspond to the signal line 118 and the power supply line 119 shown in FIG. 22, the first scanning line 119, the second scanning line 120, the third scanning line 121, and the potential supply line 12 Equivalent to 3.

[0110] The row of pixels to be operated is selected by a signal output from the scanning line driving circuit 712. The operation shown in FIG. 2 is performed simultaneously for each pixel in the same row. During the data writing period, the signals output from the signal line driver circuit 711 are written to the pixels of the selected row. At this time, a potential corresponding to the brightness data of each pixel is applied to each signal line. Input to S1 to Sm.

[0111] As shown in Figure 8, for example, when the data writing period for the i-th row is completed, Signals are written to the pixels. Note that Figure 8 shows the data writing period for each row. Therefore, the operation of the first switch 111 in FIG. 2 is excerpted and described below, which can faithfully represent this. Then, the pixels in the i-th row that have completed the data writing period move on to the light emission period, The pixel emits light according to the signal written to it.

[0112] Therefore, as long as the data writing periods for each row do not overlap, initialization can be started freely for each row. In addition, each pixel can emit light except for its own address period. Therefore, the ratio of the light emission period in one frame period (i.e., the duty ratio) can be set to It can be always large, and can be made almost 100%. Therefore, a display device with a high duty ratio can be obtained.

[0113] In addition, it is possible to set the threshold voltage writing period to be long, so that the transistor Therefore, the threshold voltage of the display device can be written to the capacitor more accurately. The reliability of the system can be improved.

[0114] The configuration of the display device shown in FIG. 7 is an example, and the present invention is not limited to this. For example, the potential supply lines P1_2 to Pn_2 are arranged in parallel with the first scanning lines G1_1 to Gn_1. The power supply line P1 does not need to be parallel to the signal lines S1 to Sm, and may be arranged in parallel to the signal lines S1 to Sm. The signal lines Pm_1 to Pm_1 do not need to be arranged in parallel with the signal lines S1 to Sm. They may be arranged in parallel with the scanning lines G1_1 to Gn_1.

[0115] In this embodiment, the third switch 113 and the fourth switch 114 are turned on and off in the same running state. The case where the control is performed using the scanning line, i.e., the third scanning line 121, is shown, but each of them is different. Alternatively, each switch may be controlled according to the timing chart of FIG. 2 using different scanning lines. .

[0116] The variation in threshold voltage includes the variation in the threshold voltage of each transistor between pixels. In addition to the differences, when focusing on a single transistor, the change in threshold voltage over time is also Furthermore, the difference in threshold voltage of each transistor is due to the manufacturing process of the transistor. This includes differences in transistor characteristics at the time of The transistor refers to a transistor that has a function of supplying current to a load such as a light emitting element. (Embodiment 2) In this embodiment, a pixel having a different configuration from that of the first embodiment is shown in FIG. The same parts as those in 1 are indicated by the same reference numerals, and the same parts or parts having similar functions are indicated by the same reference numerals. A detailed description of the minutes will be omitted.

[0117] The pixel shown in FIG. 9A includes a transistor 110, a first switch 111, a second switch The third switch 112, the third switch 113, the rectifying element 914, the first capacitance element 115, the second capacitance element The pixel has a signal line 118, a first scanning line 11, and a light emitting element 117. 9, the second scanning line 120, the third scanning line 921, the fourth scanning line 922 and the power supply line 122 The pixel shown in FIG. 9A is connected to the fourth switch 114 in FIG. The first electrode of the first capacitor 115 is connected to the rectifying element 914. The rectifying element 914 is connected to the fourth scanning line 922 via the first scanning line 914. The first electrode of the capacitor element 115 is connected to the fourth scanning line 922 so that a current flows therethrough. Of course, as shown in the first embodiment, the first switch 111 and the second switch 11 The second and fourth switches 114 may be implemented by transistors or the like. The following types of transistors are available: Schottky barrier type 951, PIN type 952, and PN type 953 shown in FIG. 9(B). In addition to the diodes, diode-connected transistors 954 and 955 are used. However, the transistors 954 and 955 are connected in a manner that allows current to flow. The polarity of the transistor must be selected appropriately depending on the direction.

[0118] When a signal of H level is input to the fourth scanning line 922, the current of the rectifying element 914 is When an L level signal is input, no current flows through the rectifying element 914. When the pixel of FIG. 9 is operated in the same manner as the pixel shown in FIG. 1, the initialization period and the threshold voltage During the writing period, an L level signal is input to the fourth scanning line 922, and during the other periods, A signal of H level is input in the rectifying element 914. A signal of L level causes only current to flow through the rectifying element 914. In addition, similar to the first embodiment, the potential corresponding to the luminance data input to the pixel is set to (V2 +Vdata), the potential of the first electrode of the second capacitor element 116 needs to be reduced to V2. Therefore, the potential is V2 minus the threshold voltage of the rectifying element 914 in the forward direction. However, V2 is an arbitrary value, and the light emitting element 117 is set to a non-light emitting state during the light emitting period. If you want to use light, you can input a potential of Vdata=0. Also, the H level signal is As described above, it is sufficient that no current flows through the rectifying element 914. The value of the forward threshold voltage of the transistor M1 should be larger than the value obtained by subtracting the forward threshold voltage of the transistor M1.

[0119] Considering the above, the pixel configuration in FIG. 9 can be operated in the same way as in FIG. 1. The variation in the current value caused by the variation in the threshold voltage of the transistor 110 can be suppressed. Therefore, a current corresponding to the brightness data can be supplied to the light emitting element 117, and the brightness In addition, it is possible to suppress variations in the degree of operation of the transistor 110 in the saturation region. In this case, the variation in brightness caused by the deterioration of the light emitting element 117 can also be suppressed. can be done.

[0120] The pixel shown in this embodiment can be applied to the display device shown in FIG. As with 1, as long as the data writing periods for each row do not overlap, initialization can be started freely for each row. In addition, each pixel can emit light except for its own address period. Therefore, the ratio of the light emission period in one frame period (i.e., the duty ratio) can be set to It can be always large and can be made almost 100%. Therefore, the brightness variation is small. A display device with a high duty ratio can be obtained.

[0121] In addition, it is possible to set the threshold voltage writing period to be long, so that the current flowing to the light emitting element can be The threshold voltage of the transistor that controls the current value to be supplied can be written more accurately to the capacitor. This improves the reliability of the display device.

[0122] This embodiment can be freely combined with the pixel configurations shown in other embodiments in addition to those shown in FIG. 1 described above. That is, the rectifying element 914 can be applied to the pixel shown in the other embodiments. It is possible to use it. (Embodiment 3) In this embodiment, a pixel having a different configuration from those in the first and second embodiments is shown in FIGS. Specifically, a pixel having a configuration in which the potential supply line 123 shown in FIG. 1 is replaced with another wiring will be described. Note that it is only necessary to supply any potential to the first electrode of the first capacitor 115. The same components as those in the first embodiment are designated by the same reference numerals. and detailed description of the same parts or parts having similar functions will be omitted.

[0123] The pixel shown in FIG. 10A includes a transistor 110, a first switch 111, a second switch switch 112, a third switch 113, a fourth switch 114, a first capacitance element 115, a second capacitance element 116, a The pixel includes a capacitor 116 and a light-emitting element 117. line 119, a second scanning line 120, a third scanning line 121 and a power supply line 122. .

[0124] In the pixel shown in FIG. 1 described in Embodiment 1, the first electrode of the first capacitor 115 is connected to the fourth switch. 10(A) is connected to the potential supply line 123 via the switch 114. This is not limited to the potential supply line 123, but can be connected to the During the threshold voltage writing period, a predetermined voltage is maintained in the first capacitance element 115. This is because it is sufficient to supply a potential to the first electrode. The line 122 can be used. In this way, the first electrode of the first capacitor 115 is supplied with a potential By substituting the power supply line 122 for the wiring that supplies the power, it is possible to reduce the number of wirings. The rate can be improved.

[0125] 10B, the fourth switch 114 is connected in parallel with the first capacitance element 115. That is, the first electrode of the first capacitor 115 may be connected to the fourth switch 114. In this configuration, the initialization period and During the threshold voltage writing period, a predetermined voltage is maintained in the first capacitance element 115. An electrical potential can be applied to the first electrode.

[0126] 11, the first electrode of the first capacitor element 115 is connected to the light emitting element 117. A fourth switch is connected to the counter electrode 124 or the wiring supplying a predetermined potential to the counter electrode 124. 1. The potential may be supplied from the potential supply line 123 in FIG. Instead of the potential, a predetermined potential supplied to the counter electrode 124 may be used. This makes it possible to reduce the number of wirings and improve the aperture ratio.

[0127] In addition, the first electrode of the first capacitor element 115 and the counter electrode 124 of the light emitting element 117 are connected. The wiring is not only connected to the counter electrode 124 but also connected in parallel to the counter electrode 124. By extending it, it may be used as an auxiliary wiring for the counter electrode. The pixel may not be limited to one pixel, but may extend to adjacent pixels or the entire pixel area. Such auxiliary wiring can reduce the resistance of the counter electrode 124. When the electrode is thinned, the resistance value can be prevented from increasing. In addition, when the resistance of the counter electrode becomes high, the voltage drop The unevenness in the brightness of the light emitting element 117 caused by the uneven in-plane potential distribution of the opposing electrode due to the Therefore, the reliability can be further improved.

[0128] Also, in the pixel configurations shown in FIGS. 10 and 11, the same operation as in the first embodiment is performed. By doing so, the variation in the current value due to the variation in the threshold voltage of the transistor 110 can be reduced. Therefore, a current corresponding to the luminance data is supplied to the light emitting element 117. This makes it possible to suppress variations in brightness. It is possible to reduce power consumption by operating at a constant value. The operating region of the light emitting element 110 is not particularly limited, but when it is operated in the saturation region, 7. The present invention also suppresses variations in the current flowing through the transistor 110 due to deterioration of the transistor 110. can be done.

[0129] The potential supply line in FIG. 1 is An arbitrary potential is supplied to the first electrode of the first capacitor 115, and a predetermined potential is applied to the first capacitor 115. Therefore, the wiring that can be used as a potential supply line is not limited to the above, and Any wiring whose potential does not change during the initialization period and the threshold voltage writing period may be used. For example, As shown in FIG. 12, it is also possible to use a first scanning line 119 or a third scanning line 121. However, when the third scanning line 121 is used, the fourth switch 114 is When selecting the type of switch, keep in mind that it may function as a rectifying element as shown in 2. It is necessary.

[0130] Furthermore, the pixel shown in this embodiment can be applied to the display device shown in FIG. As with condition 1, as long as the data writing periods for each row do not overlap, each row can be initialized freely. The start time can be set. Each pixel emits light except for its own address period. Therefore, the ratio of the light emission period to one frame period (i.e., the duty ratio) can be It can be made very large and can be made almost 100%. Therefore, the brightness variation is small. Therefore, a display device with a high duty ratio can be obtained.

[0131] In addition, it is possible to set the threshold voltage writing period to be long, so that the current flowing to the light emitting element can be The threshold voltage of the transistor that controls the current value to be supplied can be written more accurately to the capacitor. This improves the reliability of the display device.

[0132] This embodiment mode is not limited to the above, and can be freely combined with the pixel configurations shown in other embodiments. It is possible. (Fourth embodiment) In this embodiment, pixels having a different configuration from those in the first to third embodiments are shown in FIGS. 13 to 16. Although the third embodiment has been described focusing on one pixel, the wiring connected to each pixel may be It is also possible to reduce the number of wirings by sharing them between pixels. If the pixel operates in the same way, various wiring can be shared. For example, the pixel can share wiring with the neighboring pixel. An example of the method for doing so will be described in this embodiment. The same parts as those in the first embodiment are designated by common symbols and have the same parts or similar functions. A detailed description of the parts will be omitted.

[0133] The pixel 1300 shown in FIG. 13 includes a transistor 110, a first switch 111, a second switch switch 112, a third switch 113, a fourth switch 114, a first capacitance element 115, a second capacitance element 116, a third capacitance element 117, a fourth capacitance element 118, a fourth capacitance element 119, a fourth capacitance element 120, a fourth capacitance element 121, a fourth capacitance element 122, a fourth capacitance element 123, a fourth capacitance element 124, a fourth capacitance element 125, a fourth capacitance element 1 The pixel includes a first capacitor 116 and a light emitting element 117. Connected to the scan line 119, the second scan line 120, the third scan line 121 and the power line 1322 of the front row It has been done.

[0134] In the pixel shown in FIG. 1 described in Embodiment 1, the first electrode of the first capacitor 115 is connected to the fourth switch. 13, the power supply 123 is connected to the front row power supply 114. This is not limited to the potential supply line 123, and can be connected to the line 1322 during the initialization period. and a predetermined voltage is held in the first capacitor 115 during the threshold voltage writing period. This is because it is sufficient to supply a potential to the first electrode of the first capacitor 115. In this way, the power supply line 1322 of the front row can be used instead of the potential supply line. The 1300 can reduce the number of wires by sharing the wires with the pixels in the front row, and the aperture ratio can be improved.

[0135] The pixel configuration shown in FIG. 13 also operates in the same manner as in the first embodiment. This suppresses variations in the current value caused by variations in the threshold voltage of the transistor 110. Therefore, a current corresponding to the luminance data can be supplied to the light emitting element 117. This makes it possible to suppress variations in brightness. Since the transistor 110 is operated by the The operating region is not particularly limited, but when it is operated in the saturation region, the light emitting element 117 may be deteriorated. The resulting variations in the current flowing through the transistor 110 can also be suppressed.

[0136] 1. Also, as shown in the pixel 1400 of FIG. 14, the potential supply line 123 of FIG. 1 is turned on in the first scanning direction of the next row. The line 1419 may be shared. The pixel 1400 also operates in the same manner as in the first embodiment. However, the initialization period and threshold voltage writing period of the row to which the pixel 1400 belongs can be The data write period must be operated so that it does not overlap with the data write period of the row that shares the wiring. be.

[0137] 1. Also, as shown in the pixel 1500 of FIG. 15, the potential supply line 123 of FIG. 1 is turned on in the second scanning The pixel 1500 may also be shared with the line 1520. The pixel 1500 may also perform the same operation as in the first embodiment. However, the initialization period and threshold voltage writing period of the row to which the pixel 1500 belongs can be The write period overlaps with the threshold voltage write period and data write period of the row that shares the wiring. It is necessary to operate it so that it overlaps with these or not overlap with them at all. The potential supplied to the first electrode of the first capacitor element 115 is turned on or off by turning on the second switch 112. Either one of the signals to turn on or off shall be used.

[0138] In addition to the above, the potential supply line 123 in FIG. 1 is connected to the third scanning line 1 in the previous row as shown in FIG. However, the initialization period and threshold voltage of the row to which the pixel 1600 belongs may be shared with the pixel 621. The voltage write period is the threshold voltage write period and data write period for rows that share wiring. It is necessary to operate it so that it does not overlap with.

[0139] In this embodiment, the potential supply line 123 in FIG. 1 is the power supply line of the previous column, or the power supply line of the next row or the previous row. Although the case where the scanning line is shared with the row scanning line has been shown, the initialization period and the threshold voltage writing period A potential is supplied to the first electrode so that a predetermined voltage is maintained in the first capacitor element 115. Any other wiring may be used as long as it is possible to do so.

[0140] Furthermore, the pixel shown in this embodiment can be applied to the display device shown in FIG. In the display device, the constraints on the operation of each pixel and the data in each row shown in FIGS. The initialization start time for each row can be set freely within the range where the data writing period does not overlap. In addition, each pixel can emit light except during its own address period, so The ratio of the light emission period to the light emission period (i.e., duty ratio) can be made very large, and Therefore, the brightness variation is small and the duty ratio is A high display device can be obtained.

[0141] In addition, it is possible to set the threshold voltage writing period to be long, so that the current flowing to the light emitting element can be The threshold voltage of the transistor that controls the current value to be supplied can be written more accurately to the capacitor. This improves the reliability of the display device.

[0142] This embodiment mode is not limited to the above, and can be freely combined with the pixel configurations shown in other embodiments. It is possible. (Embodiment 5) In this embodiment, a pixel having a different configuration from that of the first embodiment is shown in FIG. The same parts as those in the first embodiment are designated by the same reference numerals, and the same parts or similar functions are designated by the same reference numerals. A detailed description of the parts included therein will be omitted.

[0143] The pixel shown in FIG. 29 includes a transistor 2910, a first switch 111, a second switch 112, a third switch 113, a fourth switch 114, a first capacitance element 115, a second capacitance element 116, a The pixel includes a capacitor 116 and a light-emitting element 117. The pixel includes a signal line 118, a first scan line 119, a second scanning line 120, a third scanning line 121, a power supply line 122, and a potential supply line 12 3 is connected.

[0144] The transistor 2910 in this embodiment is a multi-transistor in which two transistors are connected in series. It is a gate-type transistor and is provided in the same position as the transistor 110 in the first embodiment. However, the number of transistors connected in series is not particularly limited.

[0145] By operating the pixel shown in FIG. 29 in the same manner as the pixel shown in FIG. 1, transistor 291 It is possible to suppress the variation in the current value caused by the variation in the threshold voltage of 0. Therefore, a current corresponding to the brightness data can be supplied to the light emitting element 117, and the brightness variation can be reduced. In addition, since the potential of the counter electrode is kept constant during operation, power consumption is reduced. It is possible to reduce the power consumption. Note that the operating range of the transistor 2910 is particularly limited. However, when the light emitting element 117 is operated in the saturated region, the transistor The variation in the current flowing through 2910 can also be suppressed.

[0146] In this embodiment, the channel length L of the transistor 2910 is If the channel widths of the transistors are equal, it acts as the sum of the channel lengths of each transistor. Therefore, in the saturated region, the drain-source voltage Vds is more constant. In particular, the transistor 2910 has a long channel length L. This is effective when it is difficult to fabricate a transistor. It acts as an anti.

[0147] The transistor 2910 has a function of controlling the current value supplied to the light-emitting element 117. The type of transistor is not particularly limited as long as it is a crystalline semiconductor film. thin film transistors (TFTs), non-single-crystal silicon, represented by amorphous silicon and polycrystalline silicon Thin film transistors using crystalline semiconductor films, transistors formed using semiconductor substrates or SOI substrates transistor, MOS transistor, junction transistor, bipolar transistor, Zn Transistors using compound semiconductors such as O and a-InGaZnO, organic semiconductors and carbon A transistor using a silicon nanotube or other transistors can be applied.

[0148] 29 includes a first switch 111, a second switch 112, and a The first switch 112, the third switch 113, and the fourth switch 114 are made of transistors or the like. You can be there.

[0149] Furthermore, the pixel shown in this embodiment can be applied to the display device of FIG. As with condition 1, as long as the data writing periods for each row do not overlap, each row can be initialized freely. The start time can be set. Each pixel emits light except for its own address period. Therefore, the ratio of the light emission period to one frame period (i.e., the duty ratio) can be It can be made very large, and can even be made almost 100%. Therefore, a display device with a high duty ratio can be obtained.

[0150] In addition, it is possible to set the threshold voltage writing period to be long, so that the current flowing to the light emitting element can be The threshold voltage of the transistor that controls the current value to be supplied can be written more accurately to the capacitor. This improves the reliability of the display device.

[0151] The transistor 2910 is not limited to a series-connected transistor, but may be any of the transistors shown in FIG. A configuration in which transistors are connected in parallel as shown in transistor 3010 may also be used. The transistor 3010 allows a larger current to be supplied to the light emitting element 117. In addition, the characteristics of the two transistors connected in parallel are averaged. Therefore, the inherent characteristic variations of the transistors constituting the transistor 3010 are reduced. Therefore, if the variation is small, the variation in the threshold voltage of the transistor is small. This makes it easier to suppress variations in the current value caused by the above.

[0152] Also, each of the parallel-connected transistors shown in transistor 3010 may be further illustrated. The transistors may be connected in series as in the transistor 2910 shown in FIG.

[0153] This embodiment mode is not limited to the above, and can be freely combined with the pixel configurations shown in other embodiments. That is, the transistor 2910 or the transistor 3010 can be This can also be applied to the pixel configuration shown in the embodiment mode. (Sixth embodiment) In this embodiment, a transistor for controlling the current value supplied to a light emitting element in a pixel of the present invention is used. The pixel structure averages out the degradation of the transistors over time by switching them every period. The structure will be explained with reference to FIG.

[0154] The pixel shown in FIG. 31 includes a first transistor 3101, a second transistor 3102, a third transistor 3103, a fourth transistor 3104, a fourth transistor 3105, a fifth transistor 3106, a sixth transistor 3107, a sixth transistor 3108, a sixth transistor 3109, a sixth transistor 3101, a sixth transistor 3102, a sixth transistor 3103, a sixth transistor 3104, The first switch 3111, the second switch 3112, the third switch 3113, the fourth switch switch 3114, the fifth switch 3103, the sixth switch 3104, the first capacitance element 31 15, a second capacitor element 3116, and a light-emitting element 3117. 18, the first scanning line 3119, the second scanning line 3120, the third scanning line 3121, the power supply line 3 122 and a potential supply line 3123. Furthermore, although not shown in FIG. , the fourth and sixth switches 3103 and 3104 that control the on / off of the fifth switch 3103 and the sixth switch 3104. It is also connected to the fifth scan line. The first transistor 3101 and the second transistor 3102 are N-channel transistors. The transistor becomes conductive when the gate-source voltage (Vgs) exceeds the threshold voltage. The pixel electrode of the light emitting element 3117 is an anode, and the counter electrode 3124 is a cathode. The gate-source voltage of the transistor is Vgs, the first capacitance element 3115 and the second capacitance element 3116 are The voltages stored in the capacitance elements 3116 are denoted as Vc1 and Vc2, respectively. The threshold voltage of the first transistor 3101 is Vth1, and the threshold voltage of the second transistor 3102 is Vth2. The voltage is denoted as Vth2, and the power supply line 3122, the potential supply line 3123 and the signal line 3118 are These are also called the first wiring, second wiring, and third wiring, respectively.

[0155] A first electrode (one of a source electrode and a drain electrode) of the first transistor 3101 is The fifth switch 3103 is connected to the pixel electrode of the light emitting element 3117, and the second electrode ( The other of the source electrode and the drain electrode is connected to a power supply line 3122 via a second switch 3112. The gate electrode of the first transistor 3101 is also connected to the third switch 3 113 and the second switch 3112, and is connected to the power line 3122. The third switch 3113 is connected to the gate electrode of the first transistor 3101 and the second switch 3113. 112, and the second electrode of the first transistor 3101 and the second The node between the wiring connecting the second switch 3112 and the third switch 3113 is called a node. Let's say it's 3133.

[0156] A first electrode (one of a source electrode and a drain electrode) of the second transistor 3102 is The sixth switch 3104 is connected to the pixel electrode of the light emitting element 3117, and the second electrode ( The other of the source electrode and the drain electrode is connected to the second electrode of the first transistor 3101. The second electrode of the first transistor 3101 and the second electrode of the second transistor 31 If the connection point with the second electrode of node 3102 is node 3132, node 3132 is 33. The gate electrode of the second transistor 3102 is connected to the third switch The first transistor 310 is connected to a node 3133 via a second transistor 3113. The gate electrode of the first transistor and the gate electrode of the second transistor 3102 are connected.

[0157] Further, the gate electrodes of the first transistor 3101 and the second transistor 3102, If the connection point with the third switch 3113 is a node 3130, the node 3130 is the first The capacitor 3115 and the first switch 3111 are connected to the signal line 3118. That is, the first electrode of the first capacitor 3115 is connected to the first switch 3111. The second electrode of the first transistor 3101 and the second transistor 3102 is connected to the line 3118. The first electrode of the first capacitor 3115 is connected to the gate electrode of the fourth capacitor 3116. The node 3130 is also connected to the potential supply line 3123 via the switch 3114. It is also connected to the pixel electrode of the light emitting element 3117 via the second capacitor element 3116. That is, the first electrode of the second capacitor 3116 is connected to the first transistor 3101 and The gate electrode of the second transistor 3102 and the second electrode of the fifth switch 3103 or is connected to the first transistor 3101 and the second transistor 3102 via the sixth switch 3104. The capacitor elements are connected to the first electrode of the capacitor 3102. In some cases, the first transistor 3101 may be formed by sandwiching an insulating film therebetween. The gate capacitance of the second transistor 3102 is used to omit the second capacitor element 3116. It is also possible to

[0158] In addition, signals are applied to the first scanning line 3119, the second scanning line 3120, and the third scanning line 3121. By inputting, the first switch 3111, the second switch 3112, and the third switch 3113 are turned on, respectively. The first switch 3113 and the fourth switch 3114 are controlled to be turned on and off. 31, the fifth switch 3103 and the sixth switch 3104 are turned on and off. The scanning lines to be controlled are omitted.

[0159] A signal corresponding to the gradation of the pixel, i.e., luminance data, is input to the signal line 3118. A potential according to the voltage is input.

[0160] Next, the operation of the pixel shown in FIG. 31 will be described with reference to the timing chart of FIG. In FIG. 32, one frame period, which corresponds to the period for displaying one screenful of image, is It is divided into an initialization period, a threshold voltage writing period, a data writing period, and a light emitting period. .

[0161] The counter electrode 3124 of the light emitting element 3117 is supplied with a potential of V1 (V1: any number). In addition, the potential difference required for the light emitting element 3117 to emit light is set to V EL Then, power line 3122 has V1+V EL The potential of +Vth+α (α: any positive number) In other words, the power supply line 3122 is V1+V EL Any potential above +Vth+α is acceptable. Vth is set to the larger value of Vth1 or Vth2. The potential of 3 is not particularly limited, but is within the range of the potential input to the panel on which the pixels are formed. This eliminates the need to fabricate a separate power supply. The potential of the potential supply line 3123 is set to V2.

[0162] First, as shown in FIG. 32(A), in the initialization period, the first switch 3111 and the sixth switch The switch 3104 is turned off, and the second switch 3112, the third switch 3113, and the fourth switch 3114 are turned on. The first switch 3114 and the fifth switch 3103 are turned on. The resistor 3101 is in a conductive state, and the first capacitor element 3115 is connected to V1+V EL +Vth+ α-V2 is held in the second capacitance element 3116, and Vth+α is held in the second capacitance element 3116. In between, a predetermined voltage is applied to the first capacitor 3115 and a predetermined voltage is applied to the second capacitor 3116. In either case, it is sufficient that a voltage higher than Vth1 is maintained.

[0163] In the threshold voltage writing period shown in FIG. 32(B), the second switch 3112 is turned off. Therefore, the potential of the first electrode, i.e., the source electrode, of the first transistor 3101 gradually , and the gate-source voltage Vgs of the first transistor 3101 rises to the threshold voltage ( When Vth1 is reached, the first transistor 3101 becomes non-conductive. The voltage Vc2 held in the second capacitance element 3116 is approximately Vth1.

[0164] In the subsequent data writing period shown in FIG. 32(C), the third switch 3113 After turning off the fourth switch 3114, the first switch 3111 is turned on, and the signal A potential (V2+Vdata) corresponding to the luminance data is input from the line 3118. At this time, The voltage Vc2 held in the second capacitance element 3116 is a voltage Vc2 held in the first capacitance element 3115, the second capacitance element 3116, and the If the capacitances of the capacitance element 3116 and the light emitting element 3117 are C1, C2, and C3, respectively, then C 3>>From C1 and C2, Vth1+Vdata×(C1 / (C1+C2)).

[0165] C1 and C2 are necessary when determining the potential to be supplied from the signal line 3118. These relationships are not particularly limited. When C1>C2, Vdat Since the amplitude of a can be reduced, power consumption can be reduced. 2>When C1 is greater, the change in Vc2 caused by the on / off and off current of surrounding switches is suppressed. Due to these opposing effects, C1 and C2 are equal, and the first capacitance element 31 It is preferable that the size of the capacitor 15 and the second capacitor 3116 are the same.

[0166] If you want the light emitting element 3117 to not emit light in the next light emitting period, you can set Vdata Simply input a potential of ≦0.

[0167] Next, in the light emission period shown in FIG. 32(D), after the first switch 3111 is turned off, The second switch 3112 is turned on. At this time, the gate The source voltage Vgs is Vth1+Vdata×(C1 / (C1+C2)), and the brightness data A current corresponding to the data flows through the first transistor 3101 and the light emitting element 3117. 3117 will light up.

[0168] By this operation, the current flowing through the light emitting element 3117 is Whether the operation region of the first transistor 31 is the saturation region or the linear region, It does not depend on the threshold voltage (Vth1) of 01.

[0169] Furthermore, in the initialization period of the next frame period shown in FIG. 32(E), The third switch 3113, the fourth switch 3114 and the sixth switch 3115 are turned off. The switch 3104 is turned on. The second transistor 3102 is turned on. The capacitance element 3115 is V1+V EL +Vth+α-V2 is applied to the second capacitance element 3116. During this initialization period, the first capacitance element 3115 is held at Vth+α. If the voltage of the second capacitor element 3116 is held at least at a voltage higher than Vth2, good.

[0170] Next, in the threshold voltage writing period shown in FIG. 32(F), the second switch 3112 is Therefore, the potential of the first electrode, i.e., the source electrode, of the second transistor 3102 is gradually increases, and the gate-source voltage Vgs of the second transistor 3102 reaches the threshold When the voltage reaches the voltage (Vth2), the second transistor 3102 becomes non-conductive. Therefore, the voltage Vc2 held in the second capacitance element 3116 becomes approximately Vth2.

[0171] In the subsequent data writing period shown in FIG. 32(G), the third switch 3113 After turning off the fourth switch 3114, the first switch 3111 is turned on, and the signal A potential (V2+Vdata) corresponding to the luminance data is input from the line 3118. At this time, The voltage Vc2 held in the second capacitance element 116 is Vth2+Vdata×(C1 / (C 1+C2)).

[0172] Next, in the light emission period shown in FIG. 32(H), after the first switch 3111 is turned off, The second switch 3112 is turned on. At this time, the gate The source voltage Vgs is Vth2+Vdata×(C1 / (C1+C2)), and the brightness data A current corresponding to the data flows through the second transistor 3102 and the light-emitting element 3117, and the light-emitting element 3117 will light up.

[0173] In addition, when the operation region of the second transistor 3102 is either the saturation region or the linear region, In this case, the current flowing through the light emitting element 3117 does not depend on the threshold voltage (Vth2).

[0174] Therefore, both the first transistor 3101 and the second transistor 3102 Even if the current supplied to the light emitting element is controlled using a transistor, the threshold voltage of the transistor will vary. The current value corresponding to the brightness data is supplied to the light emitting element 31 by suppressing the variation in the current value due to the fluctuation. 17. Note that the first transistor 3101 and the second transistor By switching between 3102, the load on one transistor can be reduced. This can reduce the change in threshold voltage of the transistor over time.

[0175] From the above, the threshold voltages of the first transistor 3101 and the second transistor 3102 are The brightness variation caused by the voltage drop can be suppressed. Therefore, it is possible to reduce power consumption.

[0176] Furthermore, the first transistor 3101 and the second transistor 3102 are operated in the saturation region. When the light emitting element 3117 is degraded, the current flowing through each transistor It is also possible to suppress variations in the

[0177] Note that the first transistor 3101 and the second transistor 3102 are operated in a saturation region. In this case, it is more preferable that the channel length L of these transistors is long.

[0178] In addition, in the present invention, the variation in the current value caused by the variation in the threshold voltage of the transistor is Therefore, the current controlled by the transistor can be supplied to Therefore, the light emitting element 3117 shown in FIG. 31 is typically an EL element ( Organic EL elements, inorganic EL elements, or EL elements containing organic and inorganic materials can be applied. In addition, instead of the light emitting element 3117, an electron emitting element, a liquid crystal element, electronic ink, etc. may be applied. You can also do this.

[0179] The first transistor 3101 and the second transistor 3102 form a light-emitting element 3117 The type of transistor is not particularly limited as long as it has the function of controlling the current value supplied to the Therefore, thin film transistors (TFTs) using crystalline semiconductor films and amorphous semiconductors Thin film transistors using non-single crystal semiconductor films, such as silicon and polycrystalline silicon, Transistors formed using solid-state or SOI substrates, MOS transistors, junction transistors Transistors, bipolar transistors, compound semiconductors such as ZnO and a-InGaZnO transistors using organic semiconductors and carbon nanotubes, Other transistors may be applied.

[0180] The first switch 3111 supplies a potential corresponding to the luminance data, that is, a signal, to the image display from a signal line 3118. The timing of inputting the voltage to the first capacitor element 3115 is selected, and the voltage held in the first capacitor element 3115 and the voltage held in the first capacitor element 3116 are selected. The voltage held in the second capacitor element 3116, i.e., the voltage of the first transistor 3101 or the second transistor 3102, The gate-source voltage of the second transistor 3102 is changed. The switch 3112 is connected to the first transistor 3101 or the second transistor 3102. The timing for supplying a predetermined potential to the second electrode is selected. In addition, the second electrode of the first capacitor 3115 and the first electrode of the second capacitor 3116 are also The third switch 3113 supplies the predetermined potential. The connection between the gate electrode of the second transistor 3102 and the second electrode of each transistor The fourth switch 3114 controls the connection of the first capacitance element 3114 to the first capacitance element 3115 for each frame period. The timing for holding a predetermined voltage in the first capacitor element 3115 is selected. The first switch controls whether or not a predetermined potential is supplied to the electrode. 3111, a second switch 3112, a third switch 3113, and a fourth switch 3114 There is no particular limitation on the type of the semiconductor device as long as it has the above function. For example, a transistor or a diode may be used. Alternatively, a logic circuit that combines these may be used. The second switch 3112 and the fourth switch 3114 are connected to the There is no particular need for a third switch 3113 as long as the pixel can be given a position. However, there is no particular need for it as long as the above functions can be realized.

[0181] For example, a first switch 3111, a second switch 3112, and a third switch 3113 , the fourth switch 3114, the fifth switch 3103, and the sixth switch 3104. When N-channel transistors are used, the pixel is composed of only N-channel transistors. This allows for simplification of the manufacturing process. An amorphous semiconductor, a semi-amorphous semiconductor, or the like can be used for the semiconductor layer of the transistor. For example, amorphous silicon (a-Si:H) is an example of an amorphous semiconductor. By using these semiconductors, the manufacturing process can be further simplified. This can reduce manufacturing costs and improve yields.

[0182] The first switch 3111, the second switch 3112, the third switch 3113, The fourth switch 3114, the fifth switch 3103, and the sixth switch 3104 are connected to the transistors. When a transistor is used, the polarity (conductivity type) of the transistor is not particularly limited. It is desirable to use transistors with low current.

[0183] In addition, the first transistor 3101, the fifth switch 3103, and the second transistor 3102 and the sixth switch 3104 are interchanged as shown in FIG. That is, the first transistor 3101 and the second transistor 3102 The electrodes are connected to the first transistor 3101 and the second transistor 3102 via the second capacitor element 3116. The gate electrode of the first transistor 3101 is connected to the gate electrode of the second transistor 3102. The electrode of the second transistor is connected to the node 3132 through the fifth switch 3103. The second electrode of the capacitor 3102 is connected to a node 3132 via a sixth switch 3104. There are.

[0184] In addition, in FIG. 31 and FIG. 37, the transistor and the switch are set, that is, the first transistor The transistor 3101 and the fifth switch 3103, the second transistor 3102 and the sixth switch The number of parallel switches is 2, but the number of parallel switches is 3104. is not particularly limited.

[0185] In addition, by applying the pixel shown in this embodiment to the display device of FIG. 7, the same effect as that of the first embodiment can be obtained. As long as the data writing periods for each row do not overlap, the initialization start time for each row can be set freely. In addition, each pixel can emit light except during its own address period. Therefore, the ratio of the light emission period to one frame period (i.e., the duty ratio) is set very high. Therefore, the brightness can be adjusted to approximately 100%. A display device with a high efficiency ratio can be obtained.

[0186] In addition, it is possible to set the threshold voltage writing period to be long, so that the current flowing to the light emitting element can be The threshold voltage of the transistor that controls the current value to be supplied can be written more accurately to the capacitor. This improves the reliability of the display device.

[0187] In this embodiment, the potential supply line 3123 is the same as in the third embodiment. It may be replaced by wiring within the pixel, or may be shared with wiring in other rows as in the fourth embodiment. , the first transistor 3101 and the second transistor 3102 are each Multi-gate transistors with transistors connected in series and transistors arranged in parallel The present embodiment is not limited to these, and may use any of the pixel configurations shown in Embodiments 1 to 5. It is possible to apply (Embodiment 7) In this embodiment, a pixel having a different configuration from that of the first embodiment is shown. The same parts or parts having similar functions are shown using common symbols, and detailed descriptions are omitted. The explanation will be omitted. These are assumed to operate in the same manner as in the first embodiment.

[0188] In this embodiment, a pixel configuration is used that forcibly prevents current from flowing through the light emitting element 117. In other words, by forcibly creating a non-luminous state, afterimages are less visible, and the The object of the present invention is to obtain a display device with excellent performance.

[0189] One such pixel configuration is shown in Figure 38. The pixel shown in Figure 38 includes a transistor 110 , a first switch 111, a second switch 112, a third switch 113, a fourth switch In addition to the capacitor 114, the first capacitor 115, the second capacitor 116, and the light-emitting element 117, The pixel has a signal line 118, a first scanning line 119, a second In addition to the scanning line 120, the third scanning line 121, the power supply line 122, and the potential supply line 123, It is also connected to the scan line 3802.

[0190] In FIG. 38, a fifth switch 3801 is connected in parallel with the second capacitance element 116. Therefore, when the fifth switch 3801 is turned on, the gate of the transistor 110 Therefore, the second electrode and the first electrode are short-circuited. Since the gate-source voltage of the transistor 110 can be set to 0V, The fifth switch 110 is turned off, and the light emitting element 117 is made non-emitting. The on / off control of the switch 3801 is performed by a signal input to the fourth scanning line 3802. The pixels are scanned one row at a time.

[0191] By this operation, the signal written in the pixel is erased. It is possible to provide an erasing period in which the display is forced to be in a non-light emitting state until the black display is inserted. This makes afterimages less visible and improves video characteristics. .

[0192] By the way, there are two driving methods for expressing the gradation of a display device: analog gradation method and digital gradation method. The analog gradation method is a method that analogically controls the light emitting intensity of the light emitting element, and a method that There is a method to control the light emitting time of the element in an analogue manner. The method of analog control of light emission intensity is often used. On the other hand, the digital gradation method is a digital The gradation is expressed by turning on and off the light-emitting element through digital control. It has the advantage of being resistant to noise because it can be processed as a digital signal, but it has two modes: emitting and not emitting light. Since there is only one state, only two gradations can be expressed as it is. As a method for achieving multiple gradations, The area gradation method weights the product and selects the weight to display the gradation. There is also a time gray scale method in which gray scale display is performed by selecting the time scale.

[0193] When this digital gradation method is combined with the time gradation method, one frame is The frame period is divided into multiple subframe periods (SFn). An address period (T The sub-frame period is determined according to the number of display bits n. The ratio of the length of the light emitting period in each subframe period is 2 (n-1) :2 (n-2) : : 2:1, and the light emitting element emits light during each light emitting period. The difference in the total time during one frame period when the light-emitting element is emitting light is used. The longer the total time that light is emitted in one frame period, the higher the brightness. The higher the value, the shorter the brightness. Note that Figure 39 shows an example of 4-bit gradation. One frame period is divided into four subframe periods, and the combination of light emission periods is , 2 4 = 16 gradations can be expressed. The ratio of the lengths of the light emitting periods is a power of 2. Even if a subframe period is further divided, gradation expression is possible. good.

[0194] When multiple gradations are achieved using the time gradation method as described above, the light emission period of the lower bits Since the duration of the light emission period is short, the data write operation for the next sub-frame period starts immediately after the light emission period ends. If you try to start writing data during the previous subframe, it will overlap with the data writing operation during the previous subframe. Therefore, it is necessary to set the erasure period as described above within the subframe period. By doing so, it is possible to achieve light emission that is shorter than the data writing period required for all rows. That is, the light emission period can be freely set.

[0195] The present invention is not only particularly effective in analog gradation systems, but also in digital gradation systems. Even in the case of a method that combines the time gradation method with the luminance method, the light emission period can be freely set. Therefore, it is effective to provide an erasure period.

[0196] Also, a line from the power supply line 122 to the pixel electrode of the light emitting element 117 via the transistor 110 For example, the erasing period may be set by cutting off the current path between the power supply line 122 and the A new switch is added to the current path between the pixel electrode of the light emitting element 117 and the transistor 110. and an erasing period is provided by scanning the pixels row by row and turning off the switches. It is possible.

[0197] One such configuration is shown in Figure 40. The configuration in Figure 40 includes the pixel configuration in Figure 1, as well as a fifth The switch 4001 is connected between the first electrode of the transistor 110 and the node 132. The on / off of the fifth switch 4001 is input to the fourth scanning line 4002. By turning off the fifth switch 4001, It is possible to set up a leave period.

[0198] 41. Also, between the second electrode of the transistor 110 and the node 133, A fifth switch is connected between the pixel electrode of the light emitting element 117 and the node 132 to terminate the erasing period. It may be provided.

[0199] Of course, in the pixel shown in FIG. 1, when the second switch 112 is turned off, the power supply line 122 By cutting off the current path from the light emitting element 117 to the light emitting element 117, a clearing period can be provided without providing a new switch. That's fine.

[0200] In addition, the potential of the gate electrode of the transistor 110 is changed to forcibly shorten the erasing period. It can also be set up.

[0201] One such configuration is shown in Fig. 42. The configuration in Fig. 42 has a rectifying element in addition to the pixel configuration in Fig. 1. The rectifying element 4201 is connected to the gate electrode of the transistor 110 and the The transistor 110 is an N-channel transistor. If the rectifying element 4201 is a fourth transistor from the gate electrode of the transistor 110, The fourth scanning line 4202 is connected so that a current flows through it. A low level signal is input only when the resistor 110 is forcibly turned off; otherwise, a high level signal is input. When the fourth scanning line 4202 is at H level, the rectifying element 4201 When the voltage becomes L level, the current flows from the gate electrode of the transistor 110 to the fourth scanning line In this way, a current flows to the fourth scanning line 4202. The gate-source voltage of the transistor 110 is set to a threshold voltage (Vth) or less, and the transistor The L level potential is applied to the gate of the transistor 110. The potential of the output electrode is the L level potential plus the threshold voltage of the rectifying element 4201 in the forward direction. The potential must be determined taking into consideration that the potential will not fall below the specified value.

[0202] The rectifying element 4201 may be a Schottky barrier type or a PIN type as shown in FIG. 9(B). In addition to PN diodes, diode-connected transistors can also be used. Cut.

[0203] If the pixel configuration has a means for forcibly making the pixel non-luminous, the insertion of black display can prevent image retention. However, the present invention is not limited to the above configuration, since it can make the image less visible.

[0204] The switches and the like for providing the erasing period shown in this embodiment are provided in the pixel configuration shown in FIG. The present invention is not limited to the above and can be applied to the pixel configurations shown in the other embodiments.

[0205] In addition, even without providing such a switch, the initialization period can be extended by setting it longer. Therefore, the period during which the pixel described in any of the first to sixth embodiments is operated can also serve as an erasing period. When doing so, set the length of the initialization period to the period during which you want to display black to make the afterimage less visible. By doing so, it is possible to improve the video characteristics. It is also possible to provide an erasing period by turning off the power supply line 122 during the light emitting period. A black display may be inserted by making the potential of the electrode 122 equal to the potential of the counter electrode 124.

[0206] The pixel shown in this embodiment can be applied to the display device shown in the first embodiment. From the above, it is possible to realize a display device with little luminance variation and excellent moving image characteristics. can be obtained. (Embodiment 8) In this embodiment, a P-channel transistor is used as the transistor for controlling the current value supplied to the light emitting element. The case where a transistor is used will be described with reference to FIG.

[0207] The pixel shown in FIG. 46 includes a transistor 4610, a first switch 4611, a second switch A switch 4612, a third switch 4613, a fourth switch 4614, a first capacitor element 461 The pixel includes a signal line 4618, a second capacitor 4616, and a light-emitting element 4617. First scanning line 4619, second scanning line 4620, third scanning line 4621, power line 4622, and a potential supply line 4623. In this embodiment, the transistor 461 0 is a P-channel transistor, and the absolute value of its gate-source voltage (|Vgs|) exceeds the threshold voltage (|Vth|) (i.e., when Vgs falls below Vth ) is in a conductive state. 624 functions as an anode. The absolute value of the gate-source voltage of the transistor is | Vgs|, the absolute value of the threshold voltage |Vth|, the first capacitance element 4615 and the second capacitance The voltages stored in the element 4616 are denoted as Vc1 and Vc2, respectively. , the potential supply line 4623, and the signal line 4618 are connected to the first wiring, the second wiring, and the third wiring, respectively. Furthermore, the first scan line 4619, the second scan line 4620, and the third scan line 4621 may also be called the fourth wiring, fifth wiring, and sixth wiring, respectively.

[0208] A first electrode (one of a source electrode and a drain electrode) of the transistor 4610 is connected to a light-emitting element. The second electrode (the other of the source electrode and the drain electrode) is connected to the pixel electrode of the transistor 4617. The gate electrode is connected to the power supply line 4622 through the second switch 4612, and the gate electrode is connected to the power supply line 4622 through the third switch 4613. The power supply line 4622 is connected via a switch 4613 and a second switch 4612. The third switch 4613 is connected to the gate electrode of the transistor 4610 and the second switch 46 It is connected between 12.

[0209] The connection point between the gate electrode of the transistor 4610 and the third switch 4613 is The node 4630 is connected to the first capacitor 4615 and the first switch 4620. 611 to the signal line 4618. That is, the first capacitor 4615 The first electrode is connected to a signal line 4618 via a first switch 4611, and the second electrode is connected to a transistor The first electrode of the first capacitor 4615 is connected to the gate electrode of the first capacitor 4610. The node 46 is also connected to the potential supply line 4623 via the fourth switch 4614. The capacitor 30 is also connected to a first electrode of the transistor 4610 through a second capacitor 4616. That is, the first electrode of the second capacitor 4616 is connected to the transistor 4610. The gate electrode and the second electrode of the transistor 4610 are connected to the first electrode of the transistor 4610. These capacitance elements may be formed by sandwiching an insulating film between wiring, semiconductor layers, and electrodes. In some cases, the second capacitor 4616 can be omitted by using the gate capacitance of the transistor 4610. It is also possible to omit it.

[0210] In addition, signals are applied to the first scanning line 4619, the second scanning line 4620, and the third scanning line 4621. By inputting, the first switch 4611, the second switch 4612, and the third switch 4613 are turned on, respectively. The first switch 4613 and the fourth switch 4614 are controlled to be turned on and off.

[0211] The signal line 4618 is a signal corresponding to the gradation of the pixel, i.e., brightness data, which corresponds to the video signal. A potential according to the voltage is input.

[0212] Next, the operation of the pixel shown in FIG. 46 will be explained using the timing chart of FIG. 47 and FIG. In FIG. 47, one frame corresponds to the period for displaying one screenful of image. The programming period consists of an initialization period, a threshold voltage writing period, a data writing period, and a light emission period. The initialization period, threshold voltage write period, and data write period are also grouped together. There is no particular limit to the length of one frame period, but it is important to consider the flickering that occurs when viewing an image. It is preferable to set the time to at least 1 / 60 seconds or less so that flicker is not noticeable.

[0213] The counter electrode 4624 of the light emitting element 4617 is supplied with a potential of V1 (V1: any number). In addition, the potential difference required for the light emitting element 4617 to emit light is V EL Then, the power supply line 4622 has V1-V EL -|Vth|-α (α: any positive number) In other words, the power supply line 4622 is V1-V EL -|Vth|-α or less potential The potential of the potential supply line 4623 is not particularly limited, but it may be This eliminates the need to fabricate a separate power supply. Here, the potential of the potential supply line 4623 is set to V2.

[0214] First, as shown in FIG. 47(A) and FIG. 48(A), in the initialization period, the first switch 4 611 is turned off, and the second switch 4612, the third switch 4613 and the fourth switch At this time, the transistor 4610 is in a conducting state, and the first capacitor The capacitance element 4615 is V1-V EL -|Vth|-α-V2 is applied to the second capacitance element 4616. During the initialization period, the first capacitance element 4615 is held at |Vth|+α. The second capacitance element 4616 has a voltage with an absolute value higher than |Vth|. It should be retained.

[0215] In the threshold voltage writing period shown in FIG. 47(B) and FIG. 48(B), the second switch 4612 is turned off. Therefore, the gate electrode of the transistor 4610 gradually rises, The gate-source voltage Vgs of the transistor 4610 becomes the threshold voltage |Vth| By the way, the transistor 4610 is turned off. The voltage Vc2 that is maintained is approximately |Vth|.

[0216] In the subsequent data write period shown in FIG. 2(C) and FIG. 3(C), the third switch After turning off the first switch 4613 and the fourth switch 4614, the first switch 4611 is turned on. A potential (V2-Vdata) corresponding to the luminance data is input from a signal line 4618. At this time, the voltage Vc2 held in the second capacitance element 4616 is 5. The capacitances of the second capacitor element 4616 and the light emitting element 4617 are C1, C2, and C If we set it to 3, then C3>>C1, C2, and so it can be expressed as equation (4).

[0217]

number

[0218] C1 and C2 are necessary when determining the potential supplied from the signal line 4618. These relationships are not particularly limited. When C1>C2, Vdat Since the amplitude of a can be reduced, power consumption can be reduced. 2>When C1 is greater, the change in Vc2 caused by the on / off and off current of surrounding switches is suppressed. Due to these opposing effects, C1 and C2 are equal, and the first capacitance element 46 It is preferable that the capacitance of the second capacitor 4615 and the capacitance of the second capacitor 4616 are the same.

[0219] If you want the light emitting element 4617 to not emit light in the next light emitting period, you can set Vdata Simply input a potential of ≦0.

[0220] Next, in the light emission period shown in FIG. 47(D) and FIG. 48(D), the first switch 4611 is After turning it off, the second switch 4612 is turned on. At this time, the transistor 4610 The gate-source voltage is Vgs=-|Vth|-Vdata×(C1 / (C1+C2) ) and a current corresponding to the luminance data flows to the transistor 4610 and the light-emitting element 4617. The light emitting element 4617 emits light. The corresponding potential is Vgs=-|Vth|- Vdata must be determined taking into account Vdata × (C1 / (C1+C2)). There is.

[0221] Note that the current I flowing through the light emitting element 4617 is a current I that causes the transistor 4610 to operate in a saturation region. When this is done, it is expressed by equation (5).

[0222]

number

[0223] Since the transistor 4610 is a P-channel transistor, Vth<0. Therefore, equation (5) can be transformed into equation (6).

[0224]

number

[0225] When the transistor 4610 is operated in the linear region, the current I flowing through the light-emitting element is It is expressed by equation (7).

[0226]

number

[0227] Since Vth<0, equation (7) can be transformed into equation (8).

[0228]

number

[0229] where W is the channel width of the transistor 4610, L is the channel length, μ is the mobility, and Co x refers to the storage capacity.

[0230] From the equations (6) and (8), the operation region of the transistor 4610 is the saturation region, the linear region, In either case, the current flowing through the light emitting element 4617 is equal to the threshold of the transistor 4610. Therefore, the variation in the threshold voltage of the transistor 4610 does not depend on the threshold voltage (Vth). The current corresponding to the brightness data is supplied to the light emitting element 461 by suppressing the variation in the current value due to the difference. Can be supplied to 7.

[0231] From the above, the luminance variation caused by the variation in the threshold voltage of the transistor 4610 In addition, the potential of the opposing electrode is kept constant during operation, so power consumption is reduced. This allows for lower power consumption.

[0232] Furthermore, when the transistor 4610 is operated in the saturation region, the light-emitting element 46 When the light emitting element 4617 deteriorates, the brightness variation due to the deterioration of the light emitting element 4617 can be suppressed. Child 4617 V EL increases, increasing the voltage at the first or source electrode of transistor 4610. At this time, the source electrode of the transistor 4610 is connected to the second capacitor 4616. The gate electrode of the transistor 4610 is connected to the first gate of the second capacitor 4616. The source is connected to the gate electrode, and the gate electrode side is in a floating state. As the potential of the transistor 4610 decreases, the gate potential of the transistor 4610 also decreases by the same amount. Therefore, since the Vgs of the transistor 4610 does not change, even if the light-emitting element deteriorates, the transistor It does not affect the current flowing through the transistor 4610 and the light emitting element 4617. It can be seen that the current I flowing through the light emitting element does not depend on the source potential or the drain potential.

[0233] Therefore, when the transistor 4610 is operated in the saturation region, The transistor 4610 is a transistor caused by the variation in threshold voltage and the deterioration of the light-emitting element 4617. This can suppress the variation in the current flowing through 4610.

[0234] When the transistor 4610 is operated in the saturation region, breakdown and channel length modulation may occur. In order to suppress the increase in the amount of current due to More preferable.

[0235] As described above, the variation in current value caused by the variation in threshold voltage of the transistor is suppressed. Therefore, in the present invention, the supply of the current controlled by the transistor can be Therefore, the light emitting element 4617 shown in FIG. Applying EL elements (organic EL elements, inorganic EL elements, or EL elements containing organic and inorganic materials) In addition, instead of the light emitting element 4617, an electron emitting element, a liquid crystal element, an electronic ink An example in which an EL element 4917 is used as the light emitting element 4617 is shown in FIG. 49 shows the state where a current flows from the counter electrode 4624 to the pixel electrode 4911. This shows:

[0236] The transistor 4610 has a function of controlling the current value supplied to the light-emitting element 4617. As long as it is, the type is not particularly limited and various types can be used. For example, thin film transistors (TFTs) using crystalline semiconductor films, amorphous silicon and polycrystalline silicon Thin film transistors using non-single crystal semiconductor films, such as silicon dioxide (SiC), semiconductor substrates, and SOI substrates transistors, MOS transistors, junction transistors, bipolar transistors, Transistors using compound semiconductors such as ZnO and a-InGaZnO transistors using organic semiconductors and carbon nanotubes, and other transistors This can be applied to the transistor 4610.

[0237] The first switch 4611 supplies a potential corresponding to the luminance data, that is, a signal, to the image display from a signal line 4618. The timing of inputting the voltage to the first capacitor element 4615 is selected, and the voltage held in the first capacitor element 4615 and the voltage held in the first capacitor element 4616 are selected. The voltage held in the second capacitance element 4616, i.e., the gate-source voltage of the transistor 4610, The second switch 4612 changes the voltage of the transistor 4610. The timing for supplying a predetermined potential to the second electrode is selected. In addition, the second electrode of the first capacitor 4615 and the first electrode of the second capacitor 4616 The third switch 4613 supplies the predetermined potential. The fourth switch 4614 controls the connection between the first electrode and the second electrode during each frame period. The timing for holding a predetermined voltage in the first capacitor 4615 is selected for each period. It controls whether or not a predetermined potential is supplied to the first electrode of the capacitance element 4615. Therefore, the first switch 4611, the second switch 4612, the third switch 4613, The switch 4614 is not particularly limited as long as it has the above function. It may be a resistor or a diode, or a logic circuit that combines them. The switch 4611, the second switch 4612, and the fourth switch 4614 are There is no particular need for a third switch if a signal or potential can be applied to the pixel. There is no particular need for the switch 4613 as long as it can achieve the above functions.

[0238] When a transistor is used, the polarity (conductivity type) of the transistor is not particularly limited. However, it is preferable to use a transistor with low off-state current. The transistors include those with LDD regions and those with multi-gate structures. In addition, both N-channel and P-channel types are used to make CMOS switches. You may do so.

[0239] For example, the first switch 4611, the second switch 4612, the third switch 461 3. When a P-channel transistor is applied to the fourth switch 4614, The scanning line that controls the on / off of the switch receives a L level signal when you want to turn it on, and a When you want to turn it on, a high-level signal is input. In this case, a P-channel transistor Since a pixel can be constructed using only this, the manufacturing process can be simplified.

[0240] Furthermore, the pixel shown in this embodiment can be applied to the display device of FIG. Similarly, as long as the data writing periods for each row do not overlap, each row can be initialized at its own discretion. In addition, each pixel can emit light except for its own address period. Therefore, the ratio of the light emission period to one frame period (i.e., the duty ratio) can be very It can be made as large as possible, and can also be made approximately 100%. Therefore, the brightness variation is small. A display device with a high duty ratio can be obtained.

[0241] In addition, it is possible to set the threshold voltage writing period to be long, so that the current flowing to the light emitting element can be The threshold voltage of the transistor that controls the current value to be supplied can be written more accurately to the capacitor. This improves the reliability of the display device.

[0242] This embodiment can be freely combined with the pixel configurations shown in other embodiments. For example, as in the second embodiment, a rectifying element may be used for the fourth switch 4614. Alternatively, the potential supply line 4623 may be replaced with another wiring as in the third and fourth embodiments. In addition, the transistor 4610 may have the structure described in Embodiments 5 and 6. In addition, the configuration and operation shown in the seventh embodiment can also be applied. The transistor 4610 described in this embodiment may be used in other embodiments. This can also be applied to the pixel shown.

[0243] However, the polarity of the transistor that controls the current flowing to the light-emitting element determines the amount of current flowing to the rectifying element. For example, a rectifying element is used to provide an erasing period. The case where the above is true will be explained with reference to FIG.

[0244] When the transistor 4610 is a P-channel transistor, the rectifying element 5001 is connected so that a current flows from the fourth scan line 5002 to the node 4630. The scanning line 5002 outputs a high-level signal only when the transistor 4610 is forcibly turned off. The fourth scanning line 5002 is input with an L level signal, and the others are input with an L level signal. When the voltage is at the H level, no current flows through the rectifying element 5001, and when the voltage is at the H level, the fourth scanning line 500 2 to node 4630. By passing a current to node 4630 in this way, The gate potential of the transistor 4610 is increased, and the gate-source potential of the transistor 4610 is increased. By forcing the voltage below the threshold voltage (|Vth|), transistor 4610 is forced off. This operation inserts black display, making afterimages less visible and improving video characteristics. It can be done. (Embodiment 9) In this embodiment, one form of a partial cross-sectional view of a pixel of the present invention will be described with reference to FIG. In this embodiment, the transistor shown in the partial cross section is a transistor supplied to a light emitting element. It is a transistor that has the function of controlling the current value that flows through it.

[0245] First, a base film 1712 is formed on a substrate 1711 having an insulating surface. The substrate 1711 may be a glass substrate, a quartz substrate, a plastic substrate (polyimide, acrylic, etc.), or the like. ethylene terephthalate, polycarbonate, polyarylate, polyether In addition to insulating substrates such as sulfone and ceramic substrates, metal substrates (tantalum, tungsten It is also possible to use a substrate having an insulating film formed on the surface of a silicon, molybdenum, or semiconductor substrate. However, it is necessary to use a substrate that can at least withstand the heat generated during the process.

[0246] The base film 1712 is a silicon oxide film, a silicon nitride film, or a silicon oxynitride film (SiO x N y ) or the like is used, and these insulating films are formed as a single layer or as two or more layers. The film 1712 may be formed by sputtering, CVD, or the like. Although 1712 is a single layer, it can of course be multiple layers of two or more.

[0247] Next, a transistor 1713 is formed over the base film 1712. , at least a semiconductor layer 1714 and a gate insulating film 171 formed on the semiconductor layer 1714 5, and a gate electrode 171 formed on the semiconductor layer 1714 via a gate insulating film 1715. 6, and the semiconductor layer 1714 has a source region and a drain region.

[0248] The semiconductor layer 1714 may be made of amorphous silicon (a-Si:H), silicon, or silicon. Amorphous semiconductors whose main components are silicon germanium (SiGe), Semi-amorphous semiconductors are made of a mixture of amorphous and amorphous semiconductors with crystal grains of 0.5nm to 20nm in size. Microcrystalline semiconductors and crystalline semiconductors such as polysilicon (p-Si:H) can be observed. The film can be used. It is possible to observe crystal grains of 0.5 nm to 20 nm. The microcrystalline state is called microcrystal. For example, in the semiconductor layer 1714, When an amorphous semiconductor film is used, it may be formed by sputtering, CVD, or the like. When a crystalline semiconductor film is used, for example, after forming an amorphous semiconductor film, it can be further crystallized. If necessary, in addition to the above main components, in order to control the threshold voltage of the transistor, It may contain trace amounts of impurity elements (phosphorus, arsenic, boron, etc.).

[0249] Next, a gate insulating film 1715 is formed to cover the semiconductor layer 1714. The film 15 is made of a single layer or a plurality of films, for example, made of silicon oxide, silicon nitride, silicon nitride oxide, or the like. The film is formed by laminating the layers. The film formation method can be a CVD method, a sputtering method, or the like. Cut.

[0250] Subsequently, gate electrodes are formed above the semiconductor layer 1714 via gate insulating films 1715. The gate electrode 1716 may be formed as a single layer or as a layer of multiple metal films. The gate electrode may be formed by layering tantalum (Ta), tungsten (W), Titanium (Ti), molybdenum (Mo), aluminum (Al), copper (Cu), chromium (C elements selected from the group consisting of niobium (Nb), etc., or alloy materials containing these elements as the main components. For example, the first conductive layer may be made of tantalum nitride. The first conductive film and the second conductive film are made of tungsten (W). The gate electrode may be made of the following.

[0251] Next, a gate electrode 1716 or a resist formed in a desired shape is used as a mask. The semiconductor layer 1714 is selectively doped with impurities that impart n-type or p-type conductivity. In this way, a channel forming region and an impurity region (source The doped region (including the drain region, the GOLD region, and the LDD region) is also formed. Depending on the conductivity type of the impurity element, it can be an N-channel or P-channel transistor. It can be made separately from the data.

[0252] 17A and 17B, in order to form the LDD region 1720 in a self-aligned manner, the gate electrode 17 16 is covered with a silicon compound, for example, a silicon oxide film, a silicon nitride film, or an oxide film. After forming the silicon nitride film, the silicon nitride film is etched back to form sidewalls 1717 . Thereafter, impurities that impart conductivity to the semiconductor layer 1714 are added to form a source region. 1718, drain region 1719, and LDD region 1720 can be formed. Therefore, the LDD region 1720 is located below the sidewall 1717. The hole 1717 is provided to form the LDD region 1720 in a self-aligned manner. The impurities that impart conductivity include phosphorus, arsenic, boron, and the like. etc. are used.

[0253] Next, the first insulating film 1716 is formed as a first interlayer insulating film 1730, covering the gate electrode 1716. The first insulating film 1721 and the second insulating film 1722 are stacked. 1722 is a silicon oxide film, a silicon nitride film, or a silicon oxynitride film (SiO x N y ) etc. Use an inorganic insulating film or a low-dielectric-constant organic resin film (photosensitive or non-photosensitive organic resin film) Alternatively, a film containing siloxane may be used. It is a material whose skeletal structure is composed of silicon (Si) and oxygen (O) bonds, and the substituents are: Organic groups (e.g., alkyl groups, aromatic hydrocarbons) are used. Also, fluoro groups are used as substituents. It may also include:

[0254] The first insulating film 1721 and the second insulating film 1722 may be made of the same material. In this embodiment, the first interlayer insulating film 1730 has a two-layer laminated structure, but it may also have a single layer structure. Alternatively, a laminated structure of three or more layers may be used.

[0255] The first insulating film 1721 and the second insulating film 1722 can be formed by sputtering, CVD, or spin deposition. The insulating layer may be formed by a film coating method or the like, and an organic resin film or a film containing siloxane may be used. In this case, the film may be formed by a coating method.

[0256] Thereafter, a source electrode and a drain electrode 1723 are formed on the first interlayer insulating film 1730. The source electrode and the drain electrode 1723 are connected to the semiconductor substrate 1721 through contact holes. It is connected to the source region 1718 and the drain region 1719 .

[0257] The source electrode and the drain electrode 1723 are made of silver (Ag), gold (Au), or copper (Cu). , Nickel (Ni), Platinum (Pt), Palladium (Pd), Iridium (Ir), Rhodium Rh, tungsten (W), aluminum (Al), tantalum (Ta), molybdenum Mo, cadmium (Cd), zinc (Zn), iron (Fe), titanium (Ti), silicon ( Si), germanium (Ge), zirconium (Zr), barium (Ba), neodymium ( Nd) or its alloy, or its metal nitride, or a laminated film of these. This can be done.

[0258] Next, a second interlayer insulating film 1731 is formed to cover the source electrode and the drain electrode 1723. The second interlayer insulating film 1731 may be an inorganic insulating film, a resin film, or a laminate of these. The inorganic insulating film may be a silicon nitride film, a silicon oxide film, a silicon oxynitride film, or As the resin film, a film formed by laminating these materials can be used. , acrylic, polyimide amide, epoxy, etc. can be used.

[0259] The pixel electrode 1724 is formed on the second interlayer insulating film 1731. Next, the pixel electrode 172 An insulator 1725 is formed to cover the end of the insulating layer 1725. In order to facilitate the deposition of the layer 1726 containing the optical material, the upper end or It is preferable that the lower end portion is formed to have a curved surface. When positive photosensitive acrylic is used as the material for 5, the bending occurs only at the top end of the insulator 1725. It is preferable that the insulating material 1 has a curved surface with a radius of curvature (0.2 μm to 3 μm). 725, a negative type that becomes insoluble in the etchant when exposed to light, or Therefore, any positive type that is soluble in the etchant can be used. The material for the insulator 1725 is not limited to organic materials, but inorganic materials such as silicon oxide and silicon oxynitride can also be used. This can be done.

[0260] Next, a layer 1726 containing a light-emitting material and a counter electrode 1728 are formed on the pixel electrode 1724 and the insulator 1725. Forming pole 1727.

[0261] The layer 1726 containing a light-emitting material is sandwiched between the pixel electrode 1724 and the counter electrode 1727. A light emitting element 1728 is formed in the removed area.

[0262] Next, the light emitting element 1728 will be described in detail with reference to FIG. The pixel electrode 1724 and the counter electrode 1727 are the pixel electrode 1801 and the counter electrode 1802 shown in FIG. In FIG. 18(a), the pixel electrode corresponds to the anode and the counter electrode corresponds to the This is the cathode.

[0263] As shown in FIG. 18(a), a light-emitting layer is provided between a pixel electrode 1801 and a counter electrode 1802. In addition to 1813, a hole injection layer 1811, a hole transport layer 1812, an electron transport layer 1814, an electron injection These layers are formed so that the potential of the pixel electrode 1801 is equal to that of the counter electrode 1802. When a voltage is applied so that the potential of the pixel electrode 1801 is higher than that of the pixel electrode 1802, holes The layers are stacked so that ions are injected from the counter electrode 1802 side and electrons are injected from the counter electrode 1802 side.

[0264] In such a light-emitting device, holes injected from the pixel electrode 1801 and the counter electrode 18 The electrons injected from O2 are recombined in the light-emitting layer 1813, and the light-emitting material is excited. Then, when the excited luminescent material returns to the ground state, it emits light. The may be any material that can produce luminescence (electroluminescence).

[0265] There is no particular limitation on the material that forms the light-emitting layer 1813, and the light-emitting layer 1813 may be formed only from a light-emitting material. However, if concentration quenching occurs, the energy gap of the luminescent material should be smaller than that of the luminescent material. The light-emitting material is dispersed in a layer made of a material (host) that has a larger energy gap than the It is preferable that the layer is mixed so as to prevent concentration quenching of the luminescent material. The energy gap is the lowest unoccupied molecular orbital (LUMO). Unoccupied Molecular Orbital levels and highest occupied molecular orbital Road(HOMO:Highest Occupied Molecular Orbita l) The energy difference between the levels.

[0266] There are no particular limitations on the luminescent material, and any material that can emit light at a desired wavelength can be used. For example, if red light is desired, 4-dicyanomethylene-2-isopropyl propyl-6-[2-(1,1,7,7-tetramethyljulolidin-9-yl)ethenyl ]-4H-pyran (abbreviation: DCJTI), 4-dicyanomethylene-2-methyl-6-[2 -(1,1,7,7-tetramethyljulolidin-9-yl)ethenyl]-4H-pyran (abbreviation: DCJT), 4-dicyanomethylene-2-tert-butyl-6-[2-(1, 1,7,7-tetramethyljulolidin-9-yl)ethenyl]-4H-pyran (abbreviation: DCJTB), periflanthene, 2,5-dicyano-1,4-bis[2-(10-methoxazole-2-yl)methyl] 6) cis-1,1,7,7-tetramethyljulolidin-9-yl)ethenyl]benzene, etc. A substance that emits light with a peak in the emission spectrum between 00 nm and 680 nm is used. Also, if you want to get green light, you can use N,N'-dimethylquinacridone (abbreviated Name: DMQd), Coumarin 6, Coumarin 545T, Tris(8-quinolinolato)aluminum Alq, N,N'-diphenylquinacridone (DPQd), etc., 50 Use a substance that emits light with a peak in the emission spectrum between 0 nm and 550 nm. If you want to obtain blue light, you can use 9,10-bis(2-naphthyl)-te rt-Butylanthracene (abbreviation: t-BuDNA), 9,9'-bianthryl, 9,1 0-Diphenylanthracene (abbreviation: DPA) and 9,10-bis(2-naphthyl)anthracene Helical (abbreviation: DNA), bis(2-methyl-8-quinolinolato)-4-phenylphenanthroline tetrahydrogallium (BGaq), bis(2-methyl-8-quinolinolato)-4-phenyl Enolato-aluminum (BAlq) etc., with an emission spectrum from 420 nm to 500 nm A substance that exhibits peaked emission can be used.

[0267] There is no particular limitation on the material used to disperse the luminescent material. 10-Di(2-naphthyl)-2-tert-butylanthracene (abbreviation: t-BuDNA ), or 4,4'-bis(N-carbazolyl)biphenyl (abbreviation In addition to carbazole derivatives such as bis[2-(2-hydroxyphenyl)pyridine], dinato]zinc (abbreviation: Znpp2), bis[2-(2-hydroxyphenyl)benzox Metal complexes such as zinc sazolato (abbreviation: ZnBOX) can be used.

[0268] The anode material for forming the pixel electrode 1801 is not particularly limited, but it is preferable to use a material with a large work function ( (function 4.0 eV or more) metals, alloys, electrically conductive compounds, and mixtures thereof Specific examples of such anode materials include oxides of metal materials such as iridium, iodide ...-based oxides, and iodide-based oxides. Indium tin oxide (abbreviated as ITO), ITO containing silicon oxide (abbreviated as ITSO), acid Using a target made of indium chloride mixed with 2 to 20 wt% zinc oxide (ZnO), In addition to the indium zinc oxide (abbreviated as IZO) formed, gold (Au), platinum (Pt), Nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe ), cobalt (Co), copper (Cu), palladium (Pd), or nitrides of metallic materials (e.g. For example, titanium nitride can be mentioned.

[0269] On the other hand, the material forming the counter electrode 1802 is selected from those having a small work function (work function 3.8 (eV or less) metals, alloys, electrically conductive compounds, and mixtures thereof can be used. Specific examples of such cathode materials include elements belonging to Group 1 or 2 of the periodic table, i.e., Alkali metals such as lithium (Li) and cesium (Cs) or magnesium (Mg) Alkaline earth metals such as calcium (Ca), strontium (Sr), and In addition, the counter electrode 1802 and the light-emitting layer 1803 may be made of an alloy containing Mg:Ag or Al:Li. By laminating a layer having excellent electron injection properties between the counter electrode and the electrode 13, Regardless of the magnitude of the function, pixel electrodes made of Al, Ag, ITO, or ITO containing silicon oxide, etc. Various conductive materials, including those listed as materials for 801, can be used as the counter electrode 1802. In addition, the electron injection layer 1815 described later can be formed from a material having excellent electron injection properties. The same effect can be achieved by using materials that are different from the above.

[0270] In order to extract the emitted light to the outside, the pixel electrode 1801 and the counter electrode 1802 are Either one or both of them should be transparent electrodes such as ITO, or several to several dozens of electrodes that can transmit visible light. Preferably, the electrode is formed to a thickness of nm.

[0271] Between the pixel electrode 1801 and the light-emitting layer 1813, a hole transport layer is provided as shown in FIG. The hole transport layer transports holes injected from the pixel electrode 1801 to the light emitting layer 18 The hole transport layer 1812 is a layer having a function of transporting the electrons to the pixel electrode 13. By separating the electrode 1801 and the light-emitting layer 1813, the light emission is quenched due to the metal. This can be prevented.

[0272] The hole transporting layer 1812 is preferably formed using a substance with a high hole transporting property. Especially 1×10 -6 cm 2 Formed using a material with hole mobility of / Vs or higher Note that a substance with a high hole-transporting property is a substance in which the mobility of holes is higher than that of electrons. Specific examples of materials that can be used to form the hole-transporting layer 1812 include: 4'-Bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB) , 4,4'-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl (abbreviation Name: TPD), 4,4',4''-tris(N,N-diphenylamino)triphenyla amine (abbreviation: TDATA), 4,4',4''-tris[N-(3-methylphenyl)- N-phenylamino]triphenylamine (abbreviation: MTDATA), 4,4'-bis{N -[4-(N,N-di-m-tolylamino)phenyl]-N-phenylamino}biphenyl (abbreviation: DNTPD), 1,3,5-tris[N,N-di(m-tolyl)amino]benzoate Zene (abbreviation: m-MTDAB), 4,4',4''-tris(N-carbazolyl)triflate Phenylamine (abbreviation: TCTA), phthalocyanine (abbreviation: H2Pc), copper phthalocyanine Examples include copper phthalocyanine (abbreviated as CuPc) and vanadyl phthalocyanine (abbreviated as VOPc). The hole transporting layer 1812 is formed by combining two or more layers made of the above-mentioned materials. It may be a layer of a multi-layer structure.

[0273] In addition, as shown in FIG. 18(a), an electron The electron transport layer 1814 may be formed on the surface of the electron-transporting layer 1814. The electron transport layer 1813 functions to transport the injected electrons to the light-emitting layer 1813. By providing the layer 1814 and separating the counter electrode 1802 from the light-emitting layer 1813, light is emitted by the This can prevent quenching caused by metals in the electrode material.

[0274] The electron transport layer 1814 is not particularly limited, and may be tris(8-quinolinolato)aluminum. aluminum (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum (abbreviation: A lmq3), bis(10-hydroxybenzo[h]-quinolinato)beryllium (abbreviation: B eBq2), bis(2-methyl-8-quinolinolato)-4-phenylphenolato-aluminum Metal complexes with quinoline or benzoquinoline skeletons, such as nium (abbreviation: BAlq) In addition, those formed by bis[2-(2-hydroxybenzoyl) Bis[2-(2-phenyl)-benzoxazolato]zinc (abbreviation: Zn(BOX)2), -hydroxyphenyl)-benzothiazolato]zinc (abbreviated as Zn(BTZ)2) It is formed by a metal complex having a thiazolyl or thiazole ligand, etc. Also, 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1 ,3,4-oxadiazole (abbreviation: PBD) and 1,3-bis[5-(p-tert- butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD -7), 3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenyl) 3-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), (4-ethylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazo p-EtTAZ, Bathophenanthroline (BPhen), Bathocu The electron transport layer 181 may be formed using proline (abbreviation: BCP) or the like. 4 is formed using a material having a higher electron mobility than the hole mobility as described above. It is also preferable that the electron transport layer 1814 is 10 -6 cm 2 Electron transfer above / Vs It is more preferable that the electron transporting layer 1814 be formed using a material having a high conductivity. It may also have a multi-layer structure formed by combining two or more layers made of the above-mentioned materials.

[0275] Furthermore, between the pixel electrode 1801 and the hole transport layer 1812, as shown in FIG. The hole injection layer 1811 may be formed on the substrate 1811. Here, the hole injection layer functions as an anode. The layer has a function of promoting injection of holes from the electrode to the hole transport layer 1812 .

[0276] The hole injection layer 1811 is not particularly limited, and may be made of molybdenum oxide, vanadium oxide, It is formed by metal oxides such as ruthenium oxide, tungsten oxide, and manganese oxide. In addition, phthalocyanine (abbreviated as H2Pc) and copper phthalocyanine can be used. Phthalocyanine compounds such as cyanine (CuPc), 4,4-bis(N-(4-(N, N-di-m-tolylamino)phenyl)-N-phenylamino)biphenyl (abbreviation: DN Aromatic amine compounds such as poly(ethylenedioxythiophene) / poly(ethylenedioxythiophene) Hole injection can also be achieved by polymers such as poly(styrene sulfonic acid) aqueous solution (PEDOT / PSS). An inclusion layer 1811 can be formed.

[0277] In addition, a mixture of the metal oxide and a material with high hole transporting properties is formed on the pixel electrode 180. 1 and the hole transport layer 1812. Such a layer can be formed thicker without increasing the driving voltage. Since there is no increase in the temperature, the microcavity effect and the optical interference effect can be achieved by adjusting the layer thickness. Therefore, it is possible to carry out optical design that utilizes the results of the above. It is possible to manufacture a high-quality light-emitting element with little color change. The pixel electrode 1801 is affected by the unevenness that occurs on the surface of the electrode during film formation and the minute residues that remain on the electrode surface. It is possible to select a film thickness that prevents short-circuiting between the electrode 1802 and the counter electrode 1802.

[0278] In addition, as shown in FIG. 18(a), a thin film is formed between the counter electrode 1802 and the electron transport layer 1814. The electron injection layer 1815 may be an electron injection layer that functions as a cathode. The layer has a function of promoting the injection of electrons from the electrode to the electron transport layer 1814. When no electron transport layer is provided, an electron injection layer is provided between the electrode functioning as a cathode and the light emitting layer. , may assist in the injection of electrons into the light-emitting layer.

[0279] The electron injection layer 1815 is not particularly limited, and may be made of lithium fluoride (LiF), cesium fluoride, or the like. Alkali metals or alkaline earth metals such as cesium fluoride (CsF), calcium fluoride (CaF2), etc. Those formed using compounds of metals such as Alq or 4 , 4-bis(5-methylbenzoxazol-2-yl)stilbene (BzOs), etc. A material with high electron transporting properties and an alkali metal or alkali metal such as magnesium or lithium are used. Mixtures of alkali earth metals can also be used as the electron injection layer 1815 .

[0280] The hole injection layer 1811, the hole transport layer 1812, the light emitting layer 1813, and the electron transport layer 181 4. The electron injection layer 1815 can be formed by a deposition method, an ink jet method, a coating method, or the like. The pixel electrode 1801 or the counter electrode 1802 may be formed by either method. The insulating layer 12 may be formed by any method such as sputtering or vapor deposition.

[0281] The layer structure of the light-emitting element is not limited to that shown in FIG. 18(a), and may be any of those shown in FIG. 18(b). As shown in FIG. 1, the electrodes may be fabricated in order starting from the electrode that functions as the cathode. 1 is a cathode, and an electron injection layer 1815, an electron transport layer 1814, and a light-emitting layer 1816 are formed on the pixel electrode 1801. 1813, a hole transport layer 1812, a hole injection layer 1811, and a counter electrode 1802 are laminated in this order. The counter electrode 1802 functions as an anode.

[0282] Although the light-emitting element has been described as having a single light-emitting layer, it may also have a plurality of light-emitting layers. By providing a plurality of light-emitting layers and mixing the light emitted from each of the light-emitting layers, For example, in the case of a light-emitting element having two light-emitting layers, the first light-emitting layer Between the light emitting layer and the second light emitting layer, a spacing layer, a layer generating holes, and a layer generating electrons are provided. With this configuration, each emitted light is visually The light is mixed with the other light and is perceived as white light. Thus, white light can be obtained.

[0283] In addition, light is emitted from either the pixel electrode 1724 or the counter electrode 1727 in FIG. Therefore, the light is taken out through the pixel electrode 1724 or the counter electrode 1725. Either or both of 727 is made of a material that is translucent.

[0284] When only the counter electrode 1727 is made of a material having light-transmitting properties, as shown in FIG. 19(a), The emitted light passes through the counter electrode 1727 and is extracted from the opposite side of the substrate. When only the pixel electrode 17 is made of a light-transmitting material, light is emitted from the pixel electrode 17 as shown in FIG. 19(b). The pixel electrode 1724 and the counter electrode 1727 are both connected to the substrate. If they are made of a light-transmitting material, light is emitted from the pixel as shown in FIG. 19(c). The electrode 1724 and the counter electrode 1727 are taken from both the substrate side and the opposite side. It is served.

[0285] Wiring and electrodes are not limited to the above materials, but may also be made of aluminum (Al), tantalum (Ta), Tungsten (Ti), molybdenum (Mo), tungsten (W), neodymium (Nd), chromium ( Cr), Nickel (Ni), Platinum (Pt), Gold (Au), Silver (Ag), Copper (Cu), Magnesium Nesium (Mg), scandium (Sc), cobalt (Co), zinc (Zn), niobium ( Nb), silicon (Si), phosphorus (P), boron (B), arsenic (As), gallium (Ga ), indium (In), tin (Sn), or one or more elements selected from the group Compounds and alloy materials (e.g., indium) containing one or more elements selected from the above group ITO containing indium tin oxide (ITO), indium zinc oxide (IZO), and silicon oxide (ITSO), zinc oxide (ZnO), aluminum neodymium (Al-Nd), magnesium silver ( Mg-Ag) or a combination of these compounds. In addition, compounds of these elements with silicon (silicides) (e.g., aluminium silicides) can be formed. silicon, molybdenum silicon, nickel silicide, etc.) and compounds of nitrogen (e.g., nitride Titanium, tantalum nitride, molybdenum nitride, etc.) may be used. Even if silicon contains a large amount of n-type impurities (such as phosphorus) or p-type impurities (such as boron), The inclusion of these impurities improves the conductivity, making it easier to use as wiring or electrodes. Silicon can be classified into single crystal, polycrystalline (polysilicon), and amorphous (amorphous silicon). When using single crystal silicon or polycrystalline silicon, the resistance can be reduced. The size can be reduced, and amorphous silicon can be produced using a simple manufacturing process.

[0286] When aluminum or silver is used, it is possible to reduce signal delay due to its high conductivity. In addition, since etching is easy, patterning is easy and fine processing can be performed. Copper also has high conductivity, which can reduce signal delay. Butane does not cause material defects when it comes into contact with oxide semiconductors such as ITO and IZO or silicon. Furthermore, the manufacturing process can be carried out without any problems such as patterning or etching. It is desirable because it is easy to apply and has excellent heat resistance. It can be manufactured without causing problems such as material defects even when it comes into contact with any oxide semiconductor or silicon. Tungsten and neodymium are also desirable because they are easy to manufacture and have excellent heat resistance. Neodymium is desirable because it has excellent heat resistance. Silicon improves the transistor's resistance and suppresses aluminum hillocks. It can be formed simultaneously with the semiconductor layer of the photodiode, and has high heat resistance. Indium tin oxide (ITO), indium zinc oxide (IZO), I containing silicon oxide TO (ITSO), zinc oxide (ZnO), and silicon (Si) are transparent, allowing light to pass through. This is particularly desirable when used in transparent portions, such as pixel electrodes and common electrodes. It can be used as:

[0287] The wiring and electrodes are not limited to a single-layer structure formed using the above materials, but may be a multi-layer structure. For example, when it is formed in a single layer structure, the manufacturing process can be simplified, and In addition, the multi-layer structure makes use of the advantages of each material. Since it is possible to reduce the disadvantages, it is possible to form wiring and electrodes with excellent performance. For example, a structure that includes a low-resistance material (such as aluminum) as part of the multilayer structure can be used. By using a material that is highly heat-resistant, it is possible to reduce the resistance of the wiring. Such a structure (for example, a material with low heat resistance but other advantages is sandwiched between materials with high heat resistance) Such a laminated structure provides high heat resistance and offers advantages that cannot be achieved with a single layer. Therefore, for example, a layer containing aluminum can be made of molybdenum or titanium. It is desirable to use wiring or electrodes sandwiched between layers containing the same.

[0288] In addition, if there are any parts where wiring or electrodes are in direct contact with wiring or electrodes of other materials, For example, one material may be mixed into another, causing a This can change the properties of the ingredients, making them unable to fulfill their intended purpose, or causing problems during production. In such cases, it may not be possible to manufacture the product properly. This can be solved by covering the surface with indium tin oxide (ITO). If you want to bring the O) into contact with aluminum, you can place titanium or molybdenum between them. Similarly, if you want to bring silicon and aluminum into contact, you should also use titanium or molybdenum between them. It is desirable to interpose ribdenum.

[0289] Next, a transistor 1713 is formed as a staggered transistor using an amorphous semiconductor film as a semiconductor layer. A partial cross-sectional view of the pixel is shown in FIG. 20. The transistor having the tag structure will be described, and the capacitor element of the pixel will also be described. do.

[0290] As shown in FIG. 20, an undercoat film 2012 is formed on a substrate 2011. A pixel electrode 2013 is formed on the film 2012. A first electrode 2014 made of the same material is formed.

[0291] Furthermore, wiring 2015 and wiring 2016 are formed on the base film 2012, and the pixel electrode 20 The end of 13 is covered with wiring 2015. An N-type An N-type semiconductor layer 2017 and an N-type semiconductor layer 2018 having the same conductivity type are formed. In addition, a semiconductor layer 2019 is formed on the base film 2012 between the wiring 2015 and the wiring 2016. A part of the semiconductor layer 2019 is formed on the N-type semiconductor layer 2017 and the N-type semiconductor layer 2018. The semiconductor layer 2018 is made of amorphous silicon (a-Si It is not limited to amorphous semiconductors, but can also be made of semi-amorphous The semiconductor layer 2019 may be a gate insulating film. 2020 is formed on the insulating film 2020. The insulating film 2020 is made of the same material as the gate insulating film 2020. A film 2021 is also formed on the first electrode 2014 .

[0292] Furthermore, a gate electrode 2022 is formed on the gate insulating film 2020, and a transistor 2 A second electrode 2025 is formed in the same layer and made of the same material as the gate electrode 2022. 2023 is formed on the first electrode 2014 via an insulating film 2021, and the insulating film 2021 is A capacitor element 2024 is formed by sandwiching the first electrode 2014 and the second electrode 2023. In addition, the edge of the pixel electrode 2013, the transistor 2025, and the capacitor element 2024 An interlayer insulating film 2026 is formed to cover the above.

[0293] A layer containing a light-emitting material is formed on the interlayer insulating film 2026 and the pixel electrode 2013 located in the opening. The layer 2027 containing the light-emitting material is formed on the pixel electrode 201. A light emitting element 2029 is formed in the region sandwiched between the electrode 3 and the counter electrode 2028 .

[0294] 20(a) is connected to the wiring 201 as shown in FIG. 20(b). 2016 and the insulating film 2021 is formed of the same material as the first electrode 2030 and the second electrode 2031. The capacitor 2031 may be sandwiched between the electrode 2023. Although an N-channel transistor was used for the transistor 2025, a P-channel transistor was used. Jista is fine too.

[0295] Substrate 2011, base film 2012, pixel electrode 2013, gate insulating film 2020, gate electrode The electrode 2022, the interlayer insulating film 2026, the layer containing a light-emitting material 2027, and the counter electrode 2028 are The materials that can be used are the substrate 1711, the undercoat film 1712, the pixel electrode 1713, and the like, which are explained in FIG. 24, gate insulating film 1715, gate electrode 1716, interlayer insulating films 1730 and 1731, The same materials as those of the layer 1726 containing a light-emitting substance and the counter electrode 1727 can be used. The wiring 2015 and the wiring 2016 correspond to the source electrode and the drain electrode in FIG. The same material as Polar 1723 can be used.

[0296] Next, as another structure of a transistor using an amorphous semiconductor film as a semiconductor layer, The gate electrode is sandwiched between the semiconductor layers, that is, the gate electrode is located under the semiconductor layer. FIG. 21 shows a partial cross section of a pixel having a multi-gate transistor.

[0297] An underlayer film 2112 is formed on a substrate 2111. A gate electrode 2112 is formed on the underlayer film 2112. An electrode 2113 is formed. In addition, a second electrode 2113 is formed in the same layer and made of the same material as the gate electrode 2113. The gate electrode 2113 is made of the same material as the gate electrode in FIG. In addition to the materials used for the electrode 1716, phosphorus-doped polycrystalline silicon and metal-silicone Silicide, which is a compound of silicon, may also be used.

[0298] A gate insulating film 2115 is formed to cover the gate electrode 2113 and the first electrode 2114. is formed.

[0299] A semiconductor layer 2116 is formed on the gate insulating film 2115. A semiconductor layer 2117 made of the same material as the first electrode 2116 is formed on the first electrode 2114. This semiconductor layer is made of amorphous semiconductor such as amorphous silicon (a-Si:H). In addition, the present invention is not limited to this and may be applied to semi-amorphous semiconductors, microcrystalline semiconductors, etc. is also good.

[0300] On the semiconductor layer 2116, an N-type semiconductor layer 2118 having an N-type conductivity and an N-type semiconductor layer 2119 is formed on the semiconductor layer 2117, and an N-type semiconductor layer 2120 is formed on the semiconductor layer 2117.

[0301] On the N-type semiconductor layer 2118 and the N-type semiconductor layer 2119, a wiring 2121 and a wiring 2122 are formed, respectively. 122 is formed, and a transistor 2129 is formed. On the substrate 210, a conductive layer 2123 made of the same material as the wiring 2121 and the wiring 2122 is formed. The conductive layer 2123, the N-type semiconductor layer 2120, and the semiconductor layer 2117 form a second conductive layer. The second electrode and the first electrode 2114 form a gate insulating film 211. 5 is sandwiched between the capacitor elements 2130.

[0302] One end of the wiring 2121 is extended, and the wiring 2121 is in contact with the upper part of the extended wiring 2121. The element electrodes 2124 are formed.

[0303] In addition, an edge of the pixel electrode 2124, a transistor 2129, and a capacitor 2130 are covered with a An insulator 2125 is formed as shown.

[0304] A layer 2126 containing a light-emitting material and a counter electrode 2128 are formed on the pixel electrode 2124 and the insulator 2125. 127 is formed, and a layer 2126 containing a light-emitting material is formed between the pixel electrode 2124 and the counter electrode 2127. A light emitting element 2128 is formed in the sandwiched region.

[0305] The semiconductor layer 2117 and the N-type semiconductor layer 212 which are to be a part of the second electrode of the capacitor element 2130 0 does not have to be provided. In other words, the second electrode is the conductive layer 2123, and the first electrode 21 The capacitor may have a structure in which the gate insulating film 2115 is sandwiched between the gate insulating film 2114 and the conductive layer 2123. .

[0306] In addition, an N-channel transistor is used for the transistor 2129, but a P-channel transistor is used. A transistor is also fine.

[0307] In FIG. 21(a), the pixel electrode 2124 is formed before the wiring 2121 is formed. By this, a second electrode made of the same material as the pixel electrode 2124 in the same layer as shown in FIG. 21(b) is formed. A capacitor element having a structure in which a gate insulating film 2115 is sandwiched between an electrode 2131 and a first electrode 2114. 2132 may be formed.

[0308] Although we have shown a transistor with an inverse staggered channel etch structure, the channel A transistor with a protection structure may also be used. Next, regarding a transistor with a channel protection structure, This will be explained using Figure 22. In Figure 22, the same parts as in Figure 21 are used in common. The symbols are used.

[0309] The transistor 2201 having a channel protection structure shown in FIG. 22(a) is the same as that shown in FIG. 21(a). The transistor 2129 having the channel etch structure has a channel in the semiconductor layer 2116. The difference is that an insulator 2202 is provided on the region where the etching is to be performed. do.

[0310] Similarly, the transistor 2201 having a channel protection structure shown in FIG. 22(b) is The transistor 2129 with the channel etch structure shown in b) has a semiconductor layer 2116 An insulator 2202 is provided on the region where the channel is to be formed, and serves as an etching mask. It differs in that

[0311] By using an amorphous semiconductor film for the semiconductor layer of the transistor constituting the pixel of the present invention, The manufacturing cost can be reduced. The materials used are those explained in FIG. It is possible.

[0312] Furthermore, the structure of the transistor and the configuration of the capacitor element are not limited to those described above, and various configurations may be used. A transistor or a capacitor element having a structure or configuration can be used.

[0313] In addition, the semiconductor layer of the transistor is made of amorphous silicon (a-Si:H) In addition to semiconductor films made of semiconductors, semi-amorphous semiconductors, and microcrystalline semiconductors, polysilicon ( A crystalline semiconductor film such as p-Si:H may also be used.

[0314] FIG. 23 is a partial cross-sectional view of a pixel having a transistor using a crystalline semiconductor film as a semiconductor layer. The transistor 2318 shown in FIG. 23 is the same as that shown in FIG. It is a multi-gate transistor.

[0315] As shown in FIG. 23, an underlayer 2302 is formed on a substrate 2301, and a semiconductor layer The semiconductor layer 2303 is formed by shaping a crystalline semiconductor film into a desired shape. Patterning and forming.

[0316] An example of a method for manufacturing a crystalline semiconductor film is described below. First, a crystalline semiconductor film is formed on a substrate 2301 by sputtering. An amorphous silicon film is formed by a CVD method or the like. The silicon film is then crystallized by thermal crystallization, laser crystallization, or by thermal crystallization using a catalytic element such as nickel. The semiconductor film is crystallized by a crystallization method or the like to obtain a crystalline semiconductor film. The mixture may be crystallized.

[0317] In addition, the film to be crystallized is not limited to amorphous semiconductor films such as amorphous silicon films. It is not necessary to specify the material, and a semiconductor film such as a semi-amorphous semiconductor or a microcrystalline semiconductor may also be used. Alternatively, a compound semiconductor film containing an amorphous structure, such as an amorphous silicon germanium film, may be used. stomach.

[0318] When a crystalline semiconductor film is formed by thermal crystallization, a heating furnace, laser irradiation, or RTA (Rapid Thermal Annealing), or a combination of these It can be used as such.

[0319] In addition, when a crystalline semiconductor film is formed by laser crystallization, a continuous wave laser is used. CW laser beams and pulsed laser beams The laser beams that can be used here include Ar laser, Kr laser, and Gas lasers such as excimer lasers, single crystal YAG, YVO4, forsterite ( Mg2SiO4), YAlO3, GdVO4, or polycrystalline (ceramic) YAG, Y2O3, YVO4, YAlO3, GdVO4 with Nd, Yb, Cr, The medium is doped with one or more of Ti, Ho, Er, Tm, and Ta. Laser, glass laser, ruby ​​laser, alexandrite laser, Ti:sapphire laser The laser is generated by one or more of the following lasers: copper vapor laser, gold vapor laser, and The fundamental waves of such laser beams and the second harmonics of these fundamental waves can be By irradiating the fourth harmonic laser beam from the source, large crystal grains can be obtained. For example, the second harmonic (532 nm) and third harmonic (532 nm) of the Nd:YVO4 laser (fundamental wave 1064 nm) A harmonic (355 nm) can be used. At this time, the laser energy density is 0.0 1~100MW / cm 2 (preferably 0.1 to 10 MW / cm 2 ) is necessary. The scanning speed is set to about 10 to 2000 cm / sec for irradiation.

[0320] In addition, single crystal YAG, YVO4, forsterite (Mg2SiO4), YAlO3 , GdVO4, or polycrystalline (ceramic) YAG, Y2O3, YVO4, YAlO 3. GdVO4 with Nd, Yb, Cr, Ti, Ho, Er, Tm, Ta as dopants Lasers that use one or more of the above as a medium, Ar ion lasers, or The Ti:sapphire laser can be operated in continuous oscillation mode, and can be Q-switched or By performing mode locking, pulse oscillation can be achieved at an oscillation frequency of 10 MHz or more. When a laser beam is oscillated at an oscillation frequency of 10 MHz or more, the semiconductor film The next pulse is irradiated onto the semiconductor film between the time when the laser melts and when the laser solidifies. Therefore, unlike the case of using a pulsed laser with a low oscillation frequency, the solid state The liquid interface can be moved continuously, so crystals grow continuously in the scanning direction. Crystal grains can be obtained.

[0321] In addition, when a crystalline semiconductor film is formed by a thermal crystallization method using a catalytic element such as nickel, In this case, it is preferable to perform a gettering process to remove catalytic elements such as nickel after crystallization. I wish.

[0322] The above-described crystallization forms a partially crystallized region in the amorphous semiconductor film. This partially crystallized crystalline semiconductor film is patterned into a desired shape to form island-shaped semiconductor This semiconductor film is used as a semiconductor layer 2303 of a transistor.

[0323] The crystalline semiconductor layer is a channel forming region 2304 of the transistor 2318 and a source It is used for the impurity region 2305 which becomes the source region or the drain region, and also for the capacitor element 2319. It is also used in the semiconductor layer 2306 that becomes the lower electrode and the impurity region 2308. The region 2308 is not particularly required. The layer 306 may be channel doped.

[0324] Next, a gate insulating film 2309 is formed on the semiconductor layer 2303 and the lower electrode of the capacitor element 2319. Furthermore, a gate insulating film 2309 is formed on the semiconductor layer 2303. A gate electrode 2310 is formed on the semiconductor layer 2306 of the capacitor element 2319 through a gate insulating film 2309. An upper electrode 2311 made of the same material as the gate electrode 2310 is formed in the same layer via the gate electrode 2310. In this manner, the transistor 2318 and the capacitor 2319 are formed.

[0325] Next, an interlayer insulating film 2312 is formed to cover the transistor 2318 and the capacitor element 2319. On the interlayer insulating film 2312, a contact hole is formed to contact the impurity region 2305. A wiring 2313 is formed. The pixel electrode 2314 is formed on the insulating layer 2313, and the edge of the pixel electrode 2314 and the wiring 2313 are covered with the insulating layer 2313. Further, a layer 2316 containing a light-emitting material is formed on the pixel electrode 2314. and a counter electrode 2317 are formed, and a light emitting material is emitted between the pixel electrode 2314 and the counter electrode 2317. A light emitting element 2320 is formed in the region where the layer 2316 containing the light emitting element is sandwiched.

[0326] In addition, a bottom gate using a crystalline semiconductor film such as polysilicon (p-Si:H) as the semiconductor layer A partial cross section of a pixel having a gate type transistor is shown in FIG.

[0327] An underlayer 2402 is formed on a substrate 2401, and a gate electrode 2403 is formed thereon. In addition, the first gate electrode 2403 is formed in the same layer and made of the same material as the gate electrode 2403. An electrode 2404 is formed.

[0328] A gate insulating film 2405 is formed to cover the gate electrode 2403 and the first electrode 2404. is formed.

[0329] A semiconductor layer is formed on the gate insulating film 2405. The semiconductor film is an amorphous Semiconductor films such as amorphous semiconductors, semi-amorphous semiconductors, and microcrystalline semiconductors are formed by thermal crystallization or laser. The desired crystallization is performed by a crystallization method or a thermal crystallization method using a catalytic element such as nickel. The semiconductor layer is formed by patterning the semiconductor layer into the shape of the semiconductor layer.

[0330] Such a semiconductor layer is used to form a channel forming region 2406 of a transistor 2422, a LD D region 2407 and impurity region 2408 which becomes a source region or a drain region, and The region 2409 that will become the second electrode of the element 2423, the impurity region 2410, and the impurity region 24 The impurity region 2410 and the impurity region 2411 are not necessarily provided. In addition, impurities may be added to the channel forming region 2406 and the region 2409. is also good.

[0331] In the capacitor 2423, the gate insulating film 2405 is disposed between the first electrode 2404 and the semiconductor layer The second electrode is sandwiched between regions 2409 and 2408 formed from the first electrode.

[0332] Next, a first interlayer insulating film 2412 is formed to cover the semiconductor layer, and the first interlayer insulating film 24 On the substrate 12, a wiring 2413 is formed which is in contact with the impurity region 2408 through a contact hole. are.

[0333] An opening 2415 is formed in the first interlayer insulating film 2412. Transistor A second interlayer insulating film 2416 is formed to cover the insulating film 2422, the capacitor element 2423, and the opening 2415. is formed on the second interlayer insulating film 2416 through a contact hole, and the wiring 2413 and The pixel electrode 2417 is formed on the substrate 2411. An insulator 2418 is formed. Then, a layer 24 containing a light-emitting material is formed on the pixel electrode 2417. The pixel electrode 2417 and the counter electrode 2420 form a light-emitting element. A light emitting element 2421 is formed in the region where the layer 2419 containing the organic compound is sandwiched. The opening 2415 is located below the element 2421. When light is extracted from the substrate side, an opening 2415 is formed in the first interlayer insulating film 2412. Therefore, the transmittance can be increased.

[0334] By using a crystalline semiconductor film for the semiconductor layer of the transistor constituting the pixel of the present invention, For example, the scanning line driver circuit 712 and the signal line driver circuit 711 in FIG. This makes it easy to form the same integrally with the

[0335] The structure of a transistor using a crystalline semiconductor film as a semiconductor layer is the same as that described above. The same applies to the capacitance element. In this embodiment, unless otherwise specified, the materials in FIG. 17 are used appropriately. This can be done.

[0336] The transistor described in this embodiment mode can be used to emit light in the pixel described in any of Embodiments 1 to 8. It can be used as a transistor to control the current value supplied to the element. By operating the pixel as described in the first to eighth embodiments, the threshold voltage of the transistor Therefore, the variation in the current value caused by the variation in the voltage can be suppressed. This allows a current corresponding to the light emitting element to be supplied, thereby suppressing variations in brightness. In addition, power consumption can be reduced by maintaining the potential of the opposing electrode constant during operation. It is Noh.

[0337] Furthermore, by applying such pixels to the display device of FIG. 7, each pixel has its own address. Since it is possible to emit light except for the non-emission period, the ratio of the light-emitting period in one frame period (i.e., duty ratio) can be made very large, even approaching 100%. Therefore, a display device with little variation in luminance and a high duty ratio can be obtained.

[0338] In addition, it is possible to set the threshold voltage writing period to be long, so that the current flowing to the light emitting element can be The threshold voltage of the transistor that controls the current value to be supplied can be written more accurately to the capacitor. This improves the reliability of the display device. (Embodiment 10) In this embodiment, an element having a different structure from the light-emitting element shown in Embodiment 9 will be described. explain.

[0339] Light-emitting devices that utilize electroluminescence are made of organic or inorganic compounds. Generally, the former is called an organic EL element and the latter is called an inorganic EL element. are.

[0340] Inorganic EL elements are classified into dispersion-type inorganic EL elements and thin-film-type inorganic EL elements depending on the element structure. The former has a light-emitting layer in which particles of a light-emitting material are dispersed in a binder, while the latter has The difference is that it has a light-emitting layer made of a thin film of light-emitting material, but electrons accelerated by a high electric field The mechanism of light emission is similar to that of the donor level. Donor-acceptor recombination luminescence utilizing the acceptor and core levels of metal ions In general, in dispersed inorganic EL devices, the donor-atom In the case of thin-film inorganic EL devices, localized emission is often used.

[0341] The luminescent material used in this embodiment is composed of at least a base material and an impurity element that serves as a luminescence center. By changing the impurity elements contained, various The luminescent material can be produced by a variety of methods, including the solid phase method and the liquid phase method (coprecipitation method). ) and various other methods can be used. In addition, spray pyrolysis, metathesis, precursor - thermal decomposition reaction method, reverse micelle method, or a combination of these methods with high-temperature baking, A liquid phase method such as freeze-drying can also be used.

[0342] In the solid phase method, the base material and the impurity element or a compound containing the impurity element are weighed and mixed in a mortar. This method involves heating and firing in an electric furnace to cause a reaction and incorporate impurity elements into the base material. The firing temperature is preferably 700 to 1500°C. If the temperature is too low, the solid-state reaction will not proceed. If the temperature is too high, the base material will decompose. However, it is preferable to perform firing in the pellet state. However, since it is a simple method, it is highly productive and suitable for mass production.

[0343] The liquid phase method (coprecipitation method) involves mixing a base material or a compound containing the base material with an impurity element or an impurity source. This method involves reacting a compound containing a luminescent element in a solution, drying it, and then baking it. The particles are uniformly distributed and small in size, allowing the reaction to proceed even at low firing temperatures.

[0344] The base material used for the light-emitting material may be a sulfide, an oxide, or a nitride. Examples of sulfides include zinc sulfide (ZnS), cadmium sulfide (CdS), and calcium sulfide. CaS, yttrium sulfide (Y2S3), gallium sulfide (Ga2S3), sulfur Strontium (SrS), barium sulfide (BaS), etc. can be used. As the material, for example, zinc oxide (ZnO), yttrium oxide (Y2O3), etc. can be used. As the nitride, for example, aluminum nitride (AlN), gallium nitride, GaN, indium nitride (InN), etc. can be used. Lead (ZnSe), zinc telluride (ZnTe), etc. can also be used, and calcium sulfide-gallium Strontium (CaGa2S4), strontium-gallium sulfide (SrGa2S4), barium sulfide It may also be a ternary mixed crystal such as sodium-gallium (BaGa2S4).

[0345] The localized luminescence centers are manganese (Mn), copper (Cu), samarium (Sm), Terbium (Tb), Erbium (Er), Thulium (Tm), Europium (Eu), Cerium (Ce), praseodymium (Pr), etc. can be used. As the catalyst, a halogen element such as fluorine (F) or chlorine (Cl) may be added.

[0346] On the other hand, the donor level is formed as the luminescence center of donor-acceptor recombination luminescence. A light-emitting material containing one impurity element and a second impurity element that forms an acceptor level is used. The first impurity element can be, for example, fluorine (F), chlorine (Cl), aluminum (Al), or the like. The second impurity element can be, for example, copper (Cu). , silver (Ag), etc. can be used.

[0347] When synthesizing a donor-acceptor recombination luminescent material using the solid-phase method, a material, a first impurity element or a compound containing the first impurity element, and a second impurity element or a compound containing the second impurity element; Compounds containing two impurity elements were weighed and mixed in a mortar, then heated and fired in an electric furnace. The base material can be the above-mentioned base material, and the first impurity element or The compound containing the first impurity element may be, for example, fluorine (F), chlorine (Cl), sulfide (S), or the like. Aluminum (Al2S3) or the like can be used, and the second impurity element or the second impurity Compounds containing elements include, for example, copper (Cu), silver (Ag), copper sulfide (Cu2S), sulfur Silver oxide (AgS) can be used. The firing temperature is preferably 700 to 1500°C. If the temperature is too low, the solid-state reaction will not proceed, and if the temperature is too high, the base material will decompose. Although the firing may be carried out in a powder state, it is preferable to fire the material in a pellet state. It is preferable that:

[0348] In addition, as impurity elements when using a solid-state reaction, the first impurity element and the second impurity element are In this case, the impurity element is diffused. This facilitates the solid-state reaction, making it possible to obtain a uniform luminescent material. Since no extra impurity elements are added, a highly pure luminescent material can be obtained. Examples of compounds consisting of an impurity element and a second impurity element include copper chloride (CuCl), Silver chloride (AgCl) or the like can be used.

[0349] The concentration of these impurity elements is 0.01 to 10 atom % relative to the base material. The content is preferably in the range of 0.05 to 5 atom %.

[0350] In the case of a thin-film inorganic EL element, the light-emitting layer is a layer containing the above-mentioned light-emitting material, and is deposited by a resistance heating deposition method. , vacuum deposition methods such as electron beam deposition (EB deposition), and physical vapor deposition methods such as sputtering. Chemical vapor deposition (C) such as PVD, metal organic CVD, and hydride transport low pressure CVD. It can be formed by using a method such as VD, atomic layer epitaxy (ALE), or the like.

[0351] 51(A) to 51(C) show examples of thin-film inorganic EL elements that can be used as light-emitting elements. 51A to 51C, the light-emitting element includes a first electrode 5101, a light-emitting layer 5102, including a second electrode 5103.

[0352] The light-emitting elements shown in FIG. 51(B) and FIG. 51(C) are the light-emitting elements shown in FIG. 51(A), The light-emitting element shown in FIG. 51(B) has a structure in which an insulating layer is provided between the electrode and the light-emitting layer. The insulating layer 5104 is provided between the electrode 5101 and the light-emitting layer 5102, and the light-emitting layer shown in FIG. The optical element has an insulating layer 5104a between the first electrode 5101 and the light-emitting layer 5102, and a second electrode 5104b between the first electrode 5101 and the light-emitting layer 5102. An insulating layer 5104b is provided between the electrode 5103 and the light-emitting layer 5102. The light-emitting layer may be sandwiched between one of the pair of electrodes and the light-emitting layer, or may be sandwiched between the pair of electrodes and the light-emitting layer. The insulating layer may be a single layer or a laminate of multiple layers.

[0353] In addition, in FIG. 51(B), an insulating layer 5104 is provided so as to be in contact with the first electrode 5101. However, the order of the insulating layer and the light-emitting layer is reversed, and the insulating layer is placed in contact with the second electrode 5103. 5104 may be provided.

[0354] In the case of a dispersion-type inorganic EL element, particulate light-emitting material is dispersed in a binder to form a film-like light-emitting layer. If the method for producing the luminescent material does not allow for the production of particles of the desired size, The binder is a material that holds the luminescent material in granular form. It is a substance that fixes the dispersed state and maintains the shape of the light-emitting layer. The binder allows the particles to be uniformly dispersed and fixed in the light-emitting layer.

[0355] In the case of a dispersion type inorganic EL element, the method of forming the light emitting layer is a droplet ejection method that can selectively form the light emitting layer. coating methods such as printing, printing (screen printing, offset printing, etc.), and spin coating Alternatively, a dipping method, a dispenser method, or the like may be used. Although not limited to this, it is preferably in the range of 10 to 1000 nm. In the light-emitting layer containing the dye, the ratio of the light-emitting material is preferably 50 wt % or more and 80 wt % or less.

[0356] 52(A) to 52(C) show one example of a dispersion-type inorganic EL element that can be used as a light-emitting element. 52A shows an example of a light-emitting element including a first electrode 5101, a light-emitting layer 5202, a second electrode 5103, a third electrode 5104, a fourth electrode 5105, a fourth electrode 5106, a fifth electrode 5107, a sixth electrode 5108, a sixth electrode 5109, a sixth electrode 5109, a sixth electrode 5101, a sixth electrode 5102, a sixth electrode 5103, a sixth electrode 5104, a sixth electrode 5105, a sixth electrode 5106, a sixth electrode 5107, a sixth electrode 5108, a sixth electrode 5109 ... The light-emitting layer 5202 has a laminated structure of two electrodes 5103 and a light-emitting layer 5202 held by a binder. It includes optical material 5201.

[0357] The binder that can be used in this embodiment is an organic material or an inorganic material having insulating properties. It is also possible to use a mixed material of an organic material and an inorganic material. As for the mechanical insulating material, a polymer with a relatively high dielectric constant, such as cyanoethyl cellulose resin, is used. Polyethylene, polypropylene, polystyrene resin, silicone resin, epoxy resin Resins such as polyimide resins and vinylidene fluoride can be used. Heat-resistant polymers such as polybenzimidazole, Alternatively, a siloxane resin may be used. Note that the siloxane resin is a resin having an Si-O-Si bond. Siloxane is a resin containing silicon (Si) and oxygen (O) in a skeletal structure. The substituent is an organic group containing at least hydrogen (e.g., an alkyl group, an aryl group, etc.). In addition, a fluoro group may be used as a substituent. As the organic material, an organic group containing at least hydrogen and a fluoro group may be used. In addition to the above, vinyl resins such as polyvinyl alcohol and polyvinyl butyral, phenol resin, novolac resin, acrylic resin, melamine resin, urethane resin, oxazole resin Resin materials such as polybenzoxazole may also be used. High dielectric constant materials such as barium (BaTiO3) and strontium titanate (SrTiO3) The dielectric constant can also be adjusted by mixing an appropriate amount of fine particles.

[0358] The inorganic insulating material contained in the binder is silicon oxide (SiO x ), silicon nitride ( SiN x ), silicon containing oxygen and nitrogen, aluminum nitride (AlN), Aluminum or aluminum oxide (Al2O3), titanium oxide (TiO2), Ba TiO3, SrTiO3, lead titanate (PbTiO3), potassium niobate (KNbO3 ), lead niobate (PbNbO3), tantalum oxide (Ta2O5), barium tantalate ( BaTa2O6), lithium tantalate (LiTaO3), yttrium oxide (Y2O3 ), zirconium oxide (ZrO2), zinc sulfide (ZnS), and other inorganic materials The organic material can be made of a material selected from the following: By adding (by adding, etc.), the dielectric constant of the light-emitting layer made of the light-emitting material and binder can be further increased. This allows for better control and a larger dielectric constant.

[0359] In the manufacturing process, the light-emitting material is dispersed in a solution containing a binder. The solvent of the binder-containing solution that can be used is a solvent that dissolves the binder material and forms the light-emitting layer. It is possible to prepare a solution with a viscosity suitable for the forming method (various wet processes) and the desired film thickness. Such a solvent may be selected appropriately. An organic solvent or the like may be used. For example, When using siloxane resin, propylene glycol monomethyl ether, propylene glycol Glycol monomethyl ether acetate (also known as PGMEA), 3-methoxy-3 Methyl-1-butanol (also known as MMB) and the like can be used.

[0360] The light-emitting elements shown in FIGS. 52(B) and 52(C) are the light-emitting elements shown in FIG. 52(A), The light-emitting element shown in FIG. 52(B) has a structure in which an insulating layer is provided between the electrode and the light-emitting layer. The light-emitting element shown in FIG. 52(C) has an insulating layer 5104 between the electrode 5101 and the light-emitting layer 5202. The device has an insulating layer 5104a between the first electrode 5101 and the light-emitting layer 5202, and a second electrode 51 The insulating layer 5104b is disposed between the light-emitting layer 5202 and the insulating layer 5104b. The light emitting layer may be provided only between one of the pair of electrodes sandwiching the light emitting layer and the light emitting layer, or between both of the electrodes. The insulating layer may be a single layer or a laminate of multiple layers.

[0361] In addition, in FIG. 52(B), an insulating layer 5104 is provided so as to be in contact with the first electrode 5101. However, the order of the insulating layer and the light-emitting layer is reversed, and the insulating layer is placed in contact with the second electrode 5103. 5104 may be provided.

[0362] The insulating layers 5104, 5104a, and 5104b in FIGS. 51 and 52 are not particularly limited. However, it is preferable that the insulating film has high insulation resistance and dense film quality, and furthermore, the dielectric constant For example, silicon oxide (SiO2), yttrium oxide (YO 3), titanium oxide (TiO2), aluminum oxide (Al2O3), hafnium oxide (H fO2), tantalum oxide (Ta2O5), barium titanate (BaTiO3), titanic acid Strontium (SrTiO3), lead titanate (PbTiO3), silicon nitride (Si3 N4), zirconium oxide (ZrO2), etc., or a mixed film of these or a laminated film of two or more types. These insulating films can be formed by sputtering, vapor deposition, CVD, etc. The insulating layer may be formed by dispersing particles of these insulating materials in a binder. The binder material may be formed using the same material and method as the binder contained in the light-emitting layer. The film thickness is not particularly limited, but is preferably in the range of 10 to 1000 nm. .

[0363] The first electrode 5101 and the second electrode 5103 may be made of a metal, an alloy, a conductive compound, For example, the pixel electrode described in the ninth embodiment may be used. The materials used for the electrode 1801 and the counter electrode 1802 can be appropriately selected and used.

[0364] Note that the light-emitting element shown in this embodiment mode has a light-emitting layer sandwiched between a pair of electrodes, that is, a first Light emission is obtained by applying a voltage between the first electrode 5101 and the second electrode 5103 .

[0365] The inorganic EL element obtained as described above was used as a light-emitting element in the ninth embodiment. It can also be freely combined with other embodiments. (Embodiment 11) In this embodiment mode, one mode of a display device of the present invention will be described with reference to FIGS.

[0366] 25(a) is a top view showing the display device, and FIG. 25(b) is a cross-sectional view taken along line A-A' in FIG. 25(a). The display device is a plan view (cross-sectional view taken along the line A-A'). A signal line driver circuit 2501, a pixel portion 2502, and a first scanning line driver circuit 250 are shown by dotted lines. 3 and a second scanning line driver circuit 2506. These are connected to a sealing substrate 2504, a sealing The material is sealed using material 2505.

[0367] 2508 is a first scanning line driver circuit 2503, a second scanning line driver circuit 2506, and This is a wiring for transmitting a signal input to the signal line driver circuit 2501, and is connected to an external input terminal. Video signals, clock signals are transmitted from the FPC (Flexible Printed Circuit) 2509. It receives a lock signal, a start signal, etc. An IC chip is installed on the connection between the FPC2509 and the display device. chips (semiconductor chips on which memory circuits, buffer circuits, etc. are formed) 2518 and 251 9 is mounted using COG (Chip On Glass) etc. In this case, FPC Although only shown in the figure, a printed wiring board (PWB) is attached to this FPC. The display device of the present invention is not only the display device itself but also the display device to which the FPC or PWB is attached. This also includes devices with IC chips or other devices mounted. Let's say.

[0368] The cross-sectional structure will be explained with reference to Figure 25(b). and its peripheral driving circuits (first scanning line driving circuit 2503, second scanning line driving circuit 2506 and and a signal line driver circuit 2501) are formed, but here, the signal line driver circuit 2501 and A pixel portion 2502 is shown.

[0369] The signal line driver circuit 2501 includes N-channel transistors 2520 and 2521. Of course, P-channel transistors and CMOS circuits are constructed using not only transistors of the same conductivity type but also P-channel transistors. In this embodiment, a display panel in which a peripheral driving circuit is integrally formed on a substrate may be used. However, this is not necessarily required, and all or part of the peripheral driving circuitry may be implemented as an IC chip. It may be formed on a chip or the like and mounted on COG or the like.

[0370] The pixel portion 2502 uses the pixel described in any of Embodiments 1 to 8. 5(b) shows a transistor 2511 that functions as a switch and a current supplying element. The transistor 2512 that controls the value and the light emitting element 2528 are shown. A first electrode of the resistor 2512 is connected to a pixel electrode 2513 of the light-emitting element 2528 . An insulator 2514 is formed to cover the edge of the pixel electrode 2513. The border 2514 is formed by using a positive photosensitive acrylic resin film.

[0371] In order to improve the coverage, the upper or lower end of the insulator 2514 is cut off. For example, the material of the insulator 2514 is When using positive photosensitive acrylic as the insulator, the radius of curvature (0 It is preferable to have a curved surface with a thickness of 0.2 μm to 3 μm. The negative type is photosensitive and becomes insoluble in the etchant, while the Any positive type that is soluble in the insulator can be used. The material for 4 is not limited to organic materials, but inorganic materials such as silicon oxide and silicon oxynitride can also be used.

[0372] In addition, a layer 2516 containing a light-emitting material and a counter electrode 2517 are formed on the pixel electrode 2513. If at least a light-emitting layer is provided in the layer 2516 containing a light-emitting material, The other layers are not particularly limited and can be selected appropriately.

[0373] Furthermore, the sealing substrate 2504 and the substrate 2510 are bonded together using a sealing material 2505. As a result, a space 2 surrounded by the substrate 2510, the sealing substrate 2504, and the sealing material 2505 is formed. The space 2507 is provided with a light emitting element 2528. In addition to being filled with activated gas (nitrogen, argon, etc.), it is also possible to use a structure filled with sealing material 2505. This also includes the formation of

[0374] It is preferable to use an epoxy resin for the sealing material 2505. It is desirable that the material be as moisture and oxygen impermeable as possible. Materials used for this include glass substrates, quartz substrates, and FRP (Fiberglass-R) reinforced plastics), PVF (polyvinyl fluoride), polyester A plastic substrate made of polyethylene or acrylic can be used.

[0375] Note that by using the pixel described in any of Embodiments 1 to 8 in the pixel portion 2502, It is possible to suppress variations in brightness between pixels or within pixels over time, and further In addition, in the present invention, a high quality display device with a high efficiency ratio can be obtained. Since the potential is kept constant during operation, power consumption can be reduced.

[0376] As shown in FIG. 25, a signal line driver circuit 2501, a pixel portion 2502, a first scanning line driver circuit 2503, and a second scanning line driver circuit 2504 are provided. The first scanning line driver circuit 2503 and the second scanning line driver circuit 2506 are integrally formed, thereby reducing the cost of the display device. Furthermore, the signal line driver circuit 2501, the pixel portion 2502, the first scanning The transistors used in the scanning line driver circuit 2503 and the second scanning line driver circuit 2506 are the same. In the case of a single conductivity type, the manufacturing process can be simplified, leading to further cost reduction. can be done.

[0377] In this manner, the display device of the present invention can be obtained. However, the configuration of the display device of the present invention is not limited to this.

[0378] As shown in FIG. 26(a), the display device has a signal line driver circuit 2601. It may also be formed on an IC chip and mounted on the display device using COG or the like. 6(a), a substrate 2600, a pixel portion 2602, a first scanning line driver circuit 2603, a second scanning line driver circuit 2604, FPC 2605, IC chip 2606, IC chip 2607 25(a) , the sealing substrate 2608, and the sealing material 2609 are respectively the substrate 2510, A pixel portion 2502, a first scanning line driver circuit 2503, a second scanning line driver circuit 2506, an FP C2509, IC chip 2518, IC chip 2519, sealing substrate 2504, sealing material 2 Equivalent to 505.

[0379] In other words, only the signal line driver circuit, which requires high-speed operation of the driver circuit, is made using CMOS or the like. It is formed on an IC chip to reduce power consumption. The IC chip is also made of semiconductors such as silicon wafers. By using a single chip, it is possible to achieve higher speed operation and lower power consumption.

[0380] The first scanning line driver circuit 2603 and the second scanning line driver circuit 2604 are connected to the pixel portion 260. 2, it is possible to reduce costs. 03, the second scanning line driver circuit 2604 and the pixel portion 2602 are made of transistors of the same conductivity type. By configuring the first scanning line driving circuit, further cost reduction can be achieved. By using a bootstrap circuit in the first scanning line driver circuit 2603 and the second scanning line driver circuit 2604, It is possible to prevent the output potential from becoming low. The semiconductor layers of the transistors constituting the second scanning line driver circuit 2603 and the second scanning line driver circuit 2604 are amorphous. When using fast silicon, the threshold voltage fluctuates due to degradation, so this must be corrected. It is preferable that the function be

[0381] The pixel portion 2602 is also operated using the pixels described in any of the embodiments 1 to 8. This makes it possible to suppress variations in brightness between pixels or within pixels over time. Furthermore, a high quality display device with a high duty ratio can be obtained. It is possible to reduce power consumption by operating the counter electrode at a constant potential. A functional circuit (memory or buffer) is formed at the connection between PC2605 and substrate 2600. By mounting a thin IC chip, the board area can be used effectively.

[0382] Also, the signal line driving circuit 2501, the first scanning line driving circuit 2503, and the signal line driving circuit 2611, the first scanning line driving circuit 2613, and the second scanning line driving circuit 2614 corresponding to the second scanning line driving circuit 2506 in FIG. 25(a) may be formed on an IC chip as shown in FIG. 26(b) and mounted on a display panel by COG or the like. Note that the substrate 2610, the pixel portion 2612, the FPC 2615, the IC chip 2616, the I C chip 2617, the sealing substrate 2618, and the sealing material 2619 in FIG. 26(b) correspond to the substrate 2510, the pixel portion 2502, the FPC 2509, the IC chip 2518, the IC chip 2 519, the sealing substrate 2504, and the sealing material 2505 in FIG. 25(a), respectively. substrate 2510, the pixel portion 2502, the FPC 2509, the IC chip 2518, the IC chip 2 519, the sealing substrate 2504, and the sealing material 2505, respectively.

[0383] Also, by using an amorphous semiconductor, such as amorphous silicon (a-Si:H), for the semiconductor layer of the transistor in the pixel portion 2612, cost reduction can be achieved. Furthermore, it becomes possible to fabricate a large-sized display panel.

[0384] Also, it is not necessary to provide a signal line driving circuit, a first scanning line driving circuit, and a second scanning line driving circuit in each of the row direction and the column direction of the pixels. For example, as shown in FIG. 27(a), the peripheral driving circuit 2701 formed on an IC chip may have the functions of the first scanning line driving circuit 26 13, the second scanning line driving circuit 2614, and the signal line driving circuit 2611 shown in FIG. 26(b). Note that the substrate 2700, the pixel portion 2702, the FPC 270 4, the IC chip 2705, the IC chip 2706, the sealing substrate 2707, and the sealing material 2708 in FIG. 27(a) are <着 respectively the substrate 2510, the pixel portion 2502, the FPC 2509, the IC chip 2 510, the pixel portion 2502, the FPC 2509, the IC chip 2518, the IC chip 2 It should be noted that there seems to be an incorrect "着" in the original text at line 38 which is retained as is in the translation. If this is an error, it should be corrected in the original text for a more accurate translation. 518, IC chip 2519, sealing substrate 2504, and sealing material 2505.

[0385] Fig. 27(b) is a schematic diagram illustrating the wiring connections of the display device of Fig. 27(a). 27(b), a substrate 2710, a peripheral driving circuit 2711, a pixel section 2712, an FPC 2 713, FPC2714 are shown.

[0386] FPC2713 and FPC2714 are used to connect the peripheral driver circuit 2711 to external signals and power supplies. The output from the peripheral driver circuit 2711 is input to the pixel portion 2712. The signals are input to wiring in the row and column directions connected to the pixels.

[0387] In addition, when a white light emitting element is used as the light emitting element, a color filter is provided on the sealing substrate. By doing so, full color display can be realized. The present invention can be applied to such a display device. Fig. 28 shows an example of a partial cross section of a pixel portion.

[0388] As shown in FIG. 28, a base film 2802 is formed on a substrate 2800, and a light-emitting element is formed thereon. A transistor 2801 is formed to control the value of the current supplied to A pixel electrode 2803 is formed in contact with the first electrode, and a layer 2804 containing a light-emitting material is formed thereon. A counter electrode 2805 is formed.

[0389] A layer 2804 containing a light-emitting material is sandwiched between the pixel electrode 2803 and the counter electrode 2805. The part that is in contact with the light source is the light emitting element. In FIG. 28, it is assumed that the light emits white light. Above the light-emitting element, there is a red color filter 2806R and a green color filter 2806G, and blue color filter 2806B are provided for full color display. In addition, a black matrix is ​​used to separate these color filters. (also known as BM) 2807 is provided.

[0390] The display device of this embodiment is not limited to the first to eighth embodiments, but also applies to the ninth or tenth embodiment. The above-described configurations can be appropriately combined. The present invention can also be applied to display devices with other configurations. (Embodiment 12) The display device of the present invention can be applied to various electronic devices. The display unit can be applied to electronic devices such as video cameras and digital cameras. Cameras, goggle displays, navigation systems, audio playback devices (car audio) audio, audio components, computers, game devices, mobile information terminals (mobile computers, mobile phones, portable game consoles, e-books, etc.), image playback with recording media Devices (specifically, recording media such as Digital Versatile Discs (DVDs) Examples include a device that can regenerate a body and display an image of it.

[0391] FIG. 33A shows a display, which includes a housing 3301, a support base 3302, and a display unit 3303. , a speaker section 3304, a video input terminal 3305, etc.

[0392] Note that the pixels described in any of Embodiments 1 to 8 are used in the display portion 3303. By this, it is possible to suppress variations in brightness between pixels or within pixels over time, Furthermore, a display having a high-quality display portion with a high duty ratio can be obtained. Furthermore, in the present invention, the electric potential of the counter electrode is kept constant during operation, so that power consumption can be reduced. It is possible. The display is for personal computers, television broadcast reception, This includes all display devices for displaying information, such as for displaying advertisements.

[0393] In recent years, there has been a growing need for larger displays, and As the molds become more complex, the price rises, which is a problem. Therefore, we are trying to reduce manufacturing costs, The challenge is to keep high-quality products as low as possible.

[0394] The pixel of the present invention can be manufactured using transistors of the same conductivity type, thereby reducing the number of processes. This reduces manufacturing costs. By using an amorphous semiconductor, such as amorphous silicon (a-Si:H), In this case, the driver circuit around the pixel section is integrated into the IC. When formed on a chip and mounted on a display panel using COG (Chip On Glass) etc. In addition, the signal line driver circuit with high operating speed is formed on an IC chip, and the signal line driver circuit with relatively high operating speed is formed on an IC chip. The low scanning line driver circuit is an integrated circuit consisting of transistors of the same conductivity type as the pixel section. It is okay to do so.

[0395] FIG. 33B shows a camera, which includes a main body 3311, a display unit 3312, an image receiving unit 3313, an operation unit 3314, and an operation panel 3316. It includes a key 3314, an external connection port 3315, a shutter button 3316, etc.

[0396] Note that the pixels described in any of Embodiments 1 to 8 are used in the display portion 3312. By this, it is possible to suppress variations in brightness between pixels or within pixels over time, Furthermore, a camera having a high-quality display with a high duty ratio can be obtained. In the present invention, the electric potential of the counter electrode is kept constant during operation, so that power consumption can be reduced. be.

[0397] In recent years, competition in production has intensified as digital cameras and other devices have become more sophisticated. Therefore, it is important to keep high performance at a low price.

[0398] The pixel of the present invention can be manufactured using transistors of the same conductivity type, thereby reducing the number of processes. This reduces manufacturing costs. By using an amorphous semiconductor, such as amorphous silicon (a-Si:H), In this case, the driver circuit around the pixel section is integrated into the IC. It is recommended to form it on a chip and mount it on the display panel using COG etc. The scanning line driving circuit is formed on an IC chip, and the scanning line driving circuit, which has a relatively low operating speed, is mounted together with the pixel section. Alternatively, the transistors may be integrally formed with a circuit configured of transistors of the same conductivity type.

[0399] FIG. 33C shows a computer, which includes a main body 3321, a housing 3322, a display unit 3323, It includes a keyboard 3324, an external connection port 3325, a pointing device 3326, etc. Note that the pixels described in any of Embodiments 1 to 8 are used in the display portion 3323. The invention makes it possible to suppress variations in brightness between pixels or within pixels over time. Furthermore, a computer having a high-quality display with a high duty ratio can be obtained. In the present invention, the electric potential of the counter electrode is kept constant during operation, thereby reducing power consumption. In addition, transistors or transistors of the same conductivity type are used for the transistors constituting the pixel portion. By using an amorphous semiconductor film for the semiconductor layer of the transistor, costs can be reduced.

[0400] FIG. 33(D) shows a mobile computer, which includes a main body 3331, a display unit 3332, a switch The display unit 3332 includes a touch panel 3333, operation keys 3334, an infrared port 3335, etc. The pixels described in the first to eighth embodiments are used for the display. can suppress the luminance variation over time in the pixel, and the duty ratio It is possible to obtain a mobile computer having a high quality display. In this case, the electric potential of the counter electrode is kept constant during operation, so power consumption can be reduced. In addition, the transistors that make up the pixel section are made of transistors of the same conductivity type or semiconductors of transistors. By using an amorphous semiconductor film, costs can be reduced.

[0401] FIG. 33(E) shows a portable image playback device (specifically, a DVD playback device) equipped with a recording medium. a main body 3341, a housing 3342, a display unit A 3343, a display unit B 3344, a recording medium Includes a (DVD, etc.) reading unit 3345, operation keys 3346, speaker unit 3347, etc. The display unit A3343 mainly displays image information, and the display unit B3344 mainly displays text information. In addition, the display unit A3343 and the display unit B3344 can display the The present invention uses the pixels described in the above to 8. This allows for suppression of variations in brightness over time, and also provides a high-quality display with a high duty ratio. In the present invention, the potential of the counter electrode is kept constant. In addition, the transistors that make up the pixel section can be The transistors have the same conductivity type as the transistors, and the semiconductor layer of the transistors uses an amorphous semiconductor film. This allows for cost reduction.

[0402] FIG. 33(F) shows a goggle-type display, which includes a main body 3351, a display unit 3352, and an articulated Note that the pixel described in any of Embodiments 1 to 8 is used in the display portion 3352. The present invention suppresses variations in luminance between pixels or within pixels over time. It is a goggle-type display that can control the brightness and has a high-quality display with a high duty ratio. In the present invention, the potential of the counter electrode is kept constant. This allows for lower power consumption. Low cost can be achieved by using an amorphous semiconductor film for the semiconductor layer of a conductive transistor or a transistor. It is possible to achieve this.

[0403] FIG. 33(G) shows a video camera, which includes a main body 3361, a display unit 3362, a housing 3363, External connection port 3364, remote control receiver 3365, image receiver 3366, battery 336 7, a voice input unit 3368, operation keys 3369, an eyepiece unit 3360, etc. The pixel 362 uses the pixels described in the first to eighth embodiments. Alternatively, it is possible to suppress variations in brightness over time in pixels, and furthermore, Therefore, a video camera having a high-quality display with a high image quality ratio can be obtained. It is possible to reduce power consumption by operating the device while maintaining a constant potential of the opposing electrode. The transistors that make up the pixel section are of the same conductivity type, and the semiconductor layer of the transistors is By using an amorphous semiconductor film, costs can be reduced.

[0404] FIG. 33(H) shows a mobile phone, which includes a main body 3371, a housing 3372, a display unit 3373, and a sound unit. A voice input unit 3374, a voice output unit 3375, an operation key 3376, an external connection port 3377, The display unit 3373 includes an antenna 3378 and the like. The present invention reduces the luminance variations between pixels or within pixels over time. A mobile phone having a high-quality display with a high duty ratio that can suppress noise In addition, in the present invention, the potential of the counter electrode is kept constant during operation, so that the power consumption is reduced. It is possible to reduce power consumption. By using an amorphous semiconductor film for the semiconductor layer of the transistor, costs can be reduced. This can be achieved.

[0405] In this way, the present invention can be applied to any electronic device. (Embodiment 13) In this embodiment, a configuration example of a mobile phone having a display device of the present invention in a display portion is shown. 34 will be used to explain.

[0406] The display panel 3410 is detachably mounted in the housing 3400. 00 can be changed in shape and dimensions as needed to fit the size of the display panel 3410. The housing 3400 to which the display panel 3410 is fixed is fitted into the printed circuit board 3401. Assembled as modules.

[0407] The display panel 3410 is connected to the printed circuit board 3401 via an FPC 3411. The print board 3401 is provided with a speaker 3402, a microphone 3403, a transmitting / receiving circuit 3404, and a 404, a signal processing circuit 3405 including a CPU and a controller is formed. Such a module is combined with an input means 3406 and a battery 3407, and the housing 340 The display panel 3410 is housed in a housing 3412. The pixel portion of the display panel 3410 is formed in the housing 3412. The sensor is positioned so that it can be seen through the opening window.

[0408] The display panel 3410 includes a pixel section and a part of peripheral driving circuits (a plurality of driving circuits with an operating frequency The other peripheral driving circuits (multiple driving circuits) are integrated on the substrate using transistors. The driver circuit with the highest operating frequency among the several driver circuits is formed on an IC chip, and the IC chip The chip may be mounted on the display panel 3410 using COG (Chip On Glass). Or, the IC chip is bonded by TAB (Tape Automated Bonding) or It is also possible to connect the glass substrate to a printed circuit board. The IC chip may be formed on a chip, and the chip may be mounted on the display panel using COG or the like.

[0409] Note that the pixel portion uses the pixel described in any of the embodiments 1 to 8. It is possible to suppress variations in brightness between pixels or over time, and further improve the duty cycle. A display panel 3410 having a high-quality display section with a high image quality ratio can be obtained. In the present invention, the potential of the opposing electrode is kept constant during operation, making it possible to reduce power consumption. In addition, the transistors constituting the pixel portion may be made of transistors of the same conductivity type or transistor semiconductors. By using an amorphous semiconductor film for the conductor layer, costs can be reduced.

[0410] The configuration shown in this embodiment is an example of a mobile phone, and a mobile phone with such a configuration The present invention can be applied to mobile phones of various configurations, without being limited to the above. (Embodiment 14) In this embodiment, an EL module in which a display panel and a circuit board are combined is shown in FIG. 5 and FIG. 36.

[0411] As shown in FIG. 35, a display panel 3501 includes a pixel portion 3503, a scanning line driver circuit 3504, and a and a signal line driver circuit 3505. The circuit board 3502 has, for example, a controller The display panel 350 includes a filter circuit 3506 and a signal dividing circuit 3507. 1 and the circuit board 3502 are connected by a connection wiring 3508. FPC or the like can be used.

[0412] The display panel 3501 includes a pixel section and a part of a peripheral driving circuit (a plurality of driving circuits with an operating frequency The other peripheral driving circuits (multiple driving circuits) are integrated on the substrate using transistors. The driver circuit with the highest operating frequency among the several driver circuits is formed on an IC chip, and the IC chip The chip may be mounted on the display panel 3501 using COG (Chip On Glass). Or, the IC chip is bonded by TAB (Tape Automated Bonding) or It is also possible to connect the glass substrate to a printed circuit board. The IC chip may be formed on a chip, and the chip may be mounted on the display panel using COG or the like.

[0413] Note that the pixel portion uses the pixel described in any of the embodiments 1 to 8. It is possible to suppress variations in brightness between pixels or over time, and further improve the duty cycle. A high-quality display panel 3501 with a high brightness ratio can be obtained. It is possible to reduce power consumption by operating the device with the electrode potential kept constant. The transistors that make up the transistors have the same conductivity type, and the semiconductor layer of the transistors has an amorphous The use of a semiconductor film can reduce costs.

[0414] An EL television receiver can be completed using this EL module. 36 is a block diagram showing the main components of an EL television receiver. The video signal is input to a video signal amplifier circuit 3602 and output from the video signal amplifier circuit 3602. a video signal processing circuit 3603 that converts the received signal into a color signal corresponding to each of the colors red, green, and blue; The video signal is processed by a control circuit 3506 to convert it into the input specifications of the driver circuit. The control circuit 3506 outputs signals to the scanning line side and the signal line side. In the case of digital driving, a signal dividing circuit 3507 is provided on the signal line side, and the input digital signal may be divided into m parts and supplied.

[0415] Of the signals received by the tuner 3601, the audio signal is sent to an audio signal amplifier circuit 3604. The output is supplied to a speaker 3606 via an audio signal processing circuit 3605. The circuit 3607 receives control information for the receiving station (receiving frequency) and volume from the input unit 3608, The signal is sent to the speaker 3601 and the audio signal processing circuit 3605.

[0416] For example, the EL module shown in FIG. 35 is mounted on the housing 3301 shown in FIG. 33(A) described in the twelfth embodiment. By incorporating the modules, a television receiver can be completed.

[0417] Of course, the present invention is not limited to television receivers, but may also be used with monitors of personal computers. In addition, it is also used for large-scale display panels such as information display panels at train stations and airports, and advertising display panels on the street. The display medium can be used for various purposes. (Embodiment 15) In this embodiment, an application example of the display device according to the present invention will be described.

[0418] Figure 56 shows an example in which the display device according to the present invention is integrated with a building. 5600, a display panel 5601, a speaker unit 5602, etc. Reference numeral 5603 denotes a remote control device for operating the display panel 5601.

[0419] The pixel described in any of Embodiments 1 to 8 is used in the display panel 5601. This makes it possible to suppress variations in luminance between pixels or over time within a pixel. Furthermore, a high-quality display panel with a high duty ratio can be obtained. It is possible to reduce power consumption by operating the device while maintaining a constant potential of the opposing electrode. The transistors that make up the pixel section are of the same conductivity type, and the semiconductor layer of the transistors is By using an amorphous semiconductor film, costs can be reduced.

[0420] The display device shown in FIG. 56 is provided integrally with the structure, so it does not require a large space. It can be installed without the need for a

[0421] FIG. 57 shows another example in which the display device according to the present invention is integrated with a building. The display panel 5701 is attached to the unit bath 5702 as a unit. The display panel 5701 allows the bather to view the image while taking a bath. By operating it, information can be displayed, so it can be used as an advertisement or a means of entertainment. It has the function of

[0422] The pixel described in any of Embodiments 1 to 8 is used for the display panel 5701. This makes it possible to suppress variations in luminance between pixels or over time within a pixel. Furthermore, a high-quality display panel with a high duty ratio can be obtained. It is possible to reduce power consumption by operating the device while maintaining a constant potential of the opposing electrode. The transistors that make up the pixel section are of the same conductivity type, and the semiconductor layer of the transistors is By using an amorphous semiconductor film, costs can be reduced.

[0423] The display device according to the present invention can be used not only on the side wall of the unit bathroom 5702 shown in FIG. For example, it can be integrated into a mirror or the bathtub itself. The shape of the display device may be adapted to the shape of the mirror surface or the bathtub. It may be so.

[0424] FIG. 58 shows another example in which the display device according to the present invention is provided integrally with a building. In FIG. 58, the display panel 5802 is curved to fit the curved surface of the columnar body 5801. Here, the pillar-shaped body 5801 will be described as a utility pole.

[0425] The display panel 5802 shown in Figure 58 is installed at a position higher than the human eye level. By installing the display panel 5802 on buildings that are repeatedly standing outdoors, Information can be provided to a specific number of viewers through the display panel 5802. Therefore, it is suitable to use the display panel for advertising. It is possible to display the same image by external control, and to switch images instantly. Because it is easy to use, extremely efficient information display and advertising effects can be expected. By providing a self-luminous display element on 802, it can be used as a highly visible display medium even at night. In addition, by installing the display panel 5802 on a utility pole, It is easy to secure a means of supplying power to the 802. In addition, in the event of an emergency such as a disaster, It can also be a means of quickly conveying accurate information to disaster victims.

[0426] The pixel described in any of Embodiments 1 to 8 is used for the display panel 5802. This makes it possible to suppress variations in luminance between pixels or over time within a pixel. Furthermore, a high-quality display panel with a high duty ratio can be obtained. It is possible to reduce power consumption by operating the device while maintaining a constant potential of the opposing electrode. The transistors that make up the pixel section are of the same conductivity type, and the semiconductor layer of the transistors is By using an amorphous semiconductor film, costs can be reduced. Alternatively, an organic transistor provided on the substrate may be used.

[0427] In this embodiment, the display device of the present invention is integrated with a wall, a unit bath, Although a pillar-shaped body is shown as an example, it can also be provided on various other structures.

[0428] Next, an example in which the display device according to the present invention is provided integrally with a moving object will be described.

[0429] FIG. 59 is a diagram showing an example in which the display device according to the present invention is integrated with an automobile. The display panel 5902 is provided integrally with the body 5901 of the automobile. It is possible to display on demand the information input from inside and outside the vehicle and its movements. The panel 5902 may have a navigation function.

[0430] The pixel described in any of Embodiments 1 to 8 is used for the display panel 5902. This makes it possible to suppress variations in luminance between pixels or over time within a pixel. Furthermore, a high-quality display panel with a high duty ratio can be obtained. It is possible to reduce power consumption by operating the device while maintaining a constant potential of the opposing electrode. The transistors that make up the pixel section are of the same conductivity type, and the semiconductor layer of the transistors is By using an amorphous semiconductor film, costs can be reduced.

[0431] The display device according to the present invention can be used not only in the vehicle body 5901 shown in FIG. 59 but also in various other situations. For example, glass windows, doors, steering wheels, shift levers, seat cushions, etc. The display panel 5902 may be provided integrally with the car seat, rearview mirror, etc. may be adapted to the shape of the object to be installed.

[0432] FIG. 60 is a diagram showing an example in which the display device according to the present invention is integrated with a train car. be.

[0433] FIG. 60(a) shows an example in which a display panel 6002 is provided on the glass of a door 6001 of a train car. This is a diagram showing the number of people required to switch advertisements compared to traditional paper advertisements. The display panel 6002 has the advantage of being inexpensive. The image displayed on the display can be switched instantly, so for example, The images on the display panel can be switched depending on the time of day when the passenger demographics change. By switching images instantly in this way, more effective advertising effects can be expected.

[0434] FIG. 60(b) shows the glass of the door 6001 of the train car, as well as the glass window 6003 and the ceiling. 6004 is a diagram showing an example in which a display panel 6002 is provided. The display device according to the present invention can be easily installed in places where installation was previously difficult. Therefore, an effective advertising effect can be obtained. The image displayed on the display unit can be instantly switched by the signal, This reduces the costs and time required for switching advertisements, allowing for more flexible advertising and information transmission. This becomes possible.

[0435] Note that the pixel described in any of Embodiments 1 to 8 is used in the display panel 6002 shown in FIG. The present invention suppresses variations in luminance between pixels or within pixels over time. Furthermore, a high-quality display panel with a high duty ratio can be obtained. In the present invention, the electric potential of the counter electrode is kept constant during operation, so that power consumption can be reduced. In addition, the transistors constituting the pixel portion may be transistors or transistors of the same conductivity type. By using an amorphous semiconductor film for the semiconductor layer of the transistor, costs can be reduced.

[0436] Furthermore, the display device according to the present invention can be installed in various places, not limited to the above. For example, the display device according to the present invention may be integrated with a strap, a seat, a handrail, a floor, etc. In this case, the shape of the display panel 6002 should be adapted to the shape of the object to be installed. It may be so.

[0437] FIG. 61 shows an example in which a display device according to the present invention is integrated into a passenger airplane. This is the diagram.

[0438] FIG. 61(a) shows a passenger airplane in which a display panel 6102 is provided on a ceiling 6101 above the seats. The display panel 6102 is attached to the hinge portion 610. 3 and is provided integrally with the ceiling 6101, and is mounted by the expansion and contraction of the hinge part 6103. The passengers can view the display panel 6102 at their desired position. It can display information by operating it, so it can be used for advertising and entertainment purposes. As shown in FIG. 61(b), the hinge portion can be bent to attach the unit to the ceiling 610. By storing it in 1, safety during takeoff and landing can be ensured. By lighting up the display element of the panel 6102, it can be used as a means of transmitting information and as an emergency light. It is possible.

[0439] Note that the pixels described in any of Embodiments 1 to 8 are used in the display panel 6102 shown in FIG. The present invention suppresses variations in luminance between pixels or within pixels over time. Furthermore, a high-quality display panel with a high duty ratio can be obtained. In the present invention, the electric potential of the counter electrode is kept constant during operation, so that power consumption can be reduced. In addition, the transistors constituting the pixel portion may be transistors or transistors of the same conductivity type. By using an amorphous semiconductor film for the semiconductor layer of the transistor, costs can be reduced.

[0440] The display device according to the present invention can be used in various places, not just the ceiling 6101 shown in FIG. For example, it can be integrated with the seat, seat table, armrest, window, etc. A large display panel that can be viewed by many people at the same time may be installed on the aircraft. It may be installed on a wall. In this case, the shape of the display panel 6102 must match the shape of the object to be installed. It would be good if it was a combination of the above.

[0441] In this embodiment, the moving body is a train car body, an automobile body, or an airplane body. These are examples, but are not limited to these, and include motorcycles, four-wheeled motor vehicles (including cars, buses, etc.) This can be applied to various things such as trains (including monorails, railways, etc.), ships, etc. The display device according to the invention instantaneously changes the display on the display panel inside the vehicle in response to an external signal. Therefore, by installing the display device according to the present invention on a mobile body, It can be used as an advertising board for an unspecified number of customers using mobile devices, an information board in the event of a disaster, etc. It can be used for various purposes.

[0442] The display device of this embodiment is not limited to the first to eighth embodiments, but also applies to the ninth or tenth embodiment. The display device may be appropriately combined with the above-described configuration. It is not limited to things. [Explanation of symbols]

[0443] 110 Transistor 111 First Switch 112 Second Switch 113 The Third Switch 114 The Fourth Switch 115 first capacitance element 116 Second Capacitor 117 Light-emitting element 118 Signal Line 119 First Scan Line 120 second scan line 121 Third Scan Line 122 Power line 123 potential supply line 124 Counter electrode 611 first switching transistor 612 second switching transistor 613 Third switching transistor 614 Fourth Switching Transistor 2910 Transistor 3010 Transistor 3101 First transistor 3102 Second transistor 3103 Fifth Switch 3104 6th Switch 3111 First Switch 3112 Second Switch 3113 Third Switch 3114 Fourth Switch 3115 First Capacitive Element 3116 Second Capacitor 3117 Light-emitting elements 3118 Signal Line 3119 First Scan Line 3120 Second Scan Line 3121 Third Scan Line 3122 Power line 3123 Potential supply line 3124 Counter electrode 3801 Fifth Switch 3802 4th scan line 4001 Fifth Switch 4002 4th scan line 4201 Rectifying element 4202 4th scan line 4610 transistor 4611 First Switch 4612 Second Switch 4613 Third Switch 4614 Fourth Switch 4615 First Capacitor 4616 Second Capacitor 4617 Light-emitting element 4618 Signal Line 4619 First Scan Line 4620 second scan line 4621 Third Scan Line 4622 Power line 4623 Potential supply line 4624 Counter electrode 5001 Rectifying element 5002 4th scan line

Claims

1. a first transistor, a second transistor, a third transistor, a switch, a capacitor, a light-emitting element, and a power supply line extending in a first direction; one of a source or a drain of the first transistor is electrically connected to one of a source or a drain of the second transistor; the other of the source and the drain of the second transistor is electrically connected to the power supply line; a gate of the second transistor electrically connected to a first scan line; one of the source and the drain of the third transistor is electrically connected to the gate of the first transistor; the other of the source and the drain of the third transistor is electrically connected to the one of the source and the drain of the first transistor; a gate of the third transistor electrically connected to a second scan line; a first terminal of the switch electrically connected to the light-emitting element; a second terminal of the switch electrically connected to a potential supply line; a first terminal of the capacitance element electrically connected to a gate of the first transistor; a second terminal of the capacitance element electrically connected to the light emitting element; the light-emitting element is electrically connected to the other of the source and the drain of the first transistor, a channel length direction of the second transistor is aligned with the first direction in a plan view; a channel length direction of the third transistor is a direction different from the first direction in a plan view; the first transistor includes a first region that functions as a channel formation region in a semiconductor layer; the semiconductor layer has a second region that functions as a channel formation region of the second transistor and a third region that is connected to the first region and the second region; the power supply line has a fourth region overlapping with the third region and a fifth region that is wider than the fourth region; the power supply line has a region overlapping with a first conductive layer having a region functioning as a gate electrode of the second transistor; the power supply line has a region overlapping with a second conductive layer having a region functioning as a gate electrode of the third transistor; the power supply line has a region that contacts the semiconductor layer through an opening, The fifth region has a region overlapping with the opening.

2. a first transistor, a second transistor, a third transistor, a capacitor, a switch, a light-emitting element, and a power supply line extending in a first direction; one of the source and the drain of the first transistor is always electrically connected to one of the source and the drain of the second transistor; the other of the source and the drain of the second transistor is always electrically connected to the power supply line; the gate of the second transistor is always electrically connected to the first scanning line; one of the source and the drain of the third transistor is always electrically connected to the gate of the first transistor; the other of the source and the drain of the third transistor is always electrically connected to the one of the source and the drain of the first transistor; the gate of the third transistor is always electrically connected to the second scanning line; a first terminal of the switch always electrically connected to the light-emitting element; a second terminal of the switch that is always electrically connected to a potential supply line; a first terminal of the capacitance element is always electrically connected to a gate of the first transistor; a second terminal of the capacitance element that is always electrically connected to the light emitting element; when the power supply line is in a conductive state with the light emitting element via at least a channel formation region of the first transistor and a channel formation region of the second transistor, a current of the power supply line is input to the light emitting element via at least a channel formation region of the first transistor and a channel formation region of the second transistor; a channel length direction of the second transistor is aligned with the first direction in a plan view; a channel length direction of the third transistor is a direction different from the first direction in a plan view; the first transistor includes a first region that functions as a channel formation region in a semiconductor layer; the semiconductor layer has a second region that functions as a channel formation region of the second transistor and a third region that is connected to the first region and the second region; the power supply line has a fourth region overlapping with the third region and a fifth region that is wider than the fourth region; the power supply line has a region overlapping with a first conductive layer having a region functioning as a gate electrode of the second transistor; the power supply line has a region overlapping with a second conductive layer having a region functioning as a gate electrode of the third transistor; the power supply line has a region that contacts the semiconductor layer through an opening, The fifth region has a region overlapping with the opening.

3. a first transistor, a second transistor, a third transistor, a capacitor, a switch, a light-emitting element, and a power supply line extending in a first direction; the third transistor has an oxide semiconductor in a channel formation region; one of a source or a drain of the first transistor is electrically connected to one of a source or a drain of the second transistor; the other of the source and the drain of the second transistor is electrically connected to the power supply line; a gate of the second transistor electrically connected to a first scan line; one of the source and the drain of the third transistor is electrically connected to the gate of the first transistor; the other of the source and the drain of the third transistor is electrically connected to the one of the source and the drain of the first transistor; a gate of the third transistor electrically connected to a second scan line; a first terminal of the switch electrically connected to the light-emitting element; a second terminal of the switch electrically connected to a potential supply line; a first terminal of the capacitance element electrically connected to a gate of the first transistor; a second terminal of the capacitance element electrically connected to the light emitting element; the light-emitting element is electrically connected to the other of the source and the drain of the first transistor, a channel length direction of the second transistor is aligned with the first direction in a plan view; a channel length direction of the third transistor is a direction different from the first direction in a plan view; the first transistor includes a first region that functions as a channel formation region in a semiconductor layer; the semiconductor layer has a second region that functions as a channel formation region of the second transistor and a third region that is connected to the first region and the second region; the power supply line has a fourth region overlapping with the third region and a fifth region that is wider than the fourth region; the power supply line has a region overlapping with a first conductive layer having a region functioning as a gate electrode of the second transistor; the power supply line has a region overlapping with a second conductive layer having a region functioning as a gate electrode of the third transistor; the power supply line has a region that contacts the semiconductor layer through an opening, The fifth region has a region overlapping with the opening.

4. a first transistor, a second transistor, a third transistor, a capacitor, a switch, a light-emitting element, and a power supply line extending in a first direction; the third transistor has an oxide semiconductor in a channel formation region; one of the source and the drain of the first transistor is always electrically connected to one of the source and the drain of the second transistor; the other of the source and the drain of the second transistor is always electrically connected to the power supply line; the gate of the second transistor is always electrically connected to the first scanning line; one of the source and the drain of the third transistor is always electrically connected to the gate of the first transistor; the other of the source and the drain of the third transistor is always electrically connected to the one of the source and the drain of the first transistor; the gate of the third transistor is always electrically connected to the second scanning line; a first terminal of the switch always electrically connected to the light-emitting element; a second terminal of the switch that is always electrically connected to a potential supply line; a first terminal of the capacitance element is always electrically connected to a gate of the first transistor; a second terminal of the capacitance element that is always electrically connected to the light emitting element; when the power supply line is in a conductive state with the light emitting element via at least a channel formation region of the first transistor and a channel formation region of the second transistor, a current of the power supply line is input to the light emitting element via at least a channel formation region of the first transistor and a channel formation region of the second transistor; a channel length direction of the second transistor is aligned with the first direction in a plan view; a channel length direction of the third transistor is a direction different from the first direction in a plan view; the first transistor includes a first region that functions as a channel formation region in a semiconductor layer; the semiconductor layer has a second region that functions as a channel formation region of the second transistor and a third region that is connected to the first region and the second region; the power supply line has a fourth region overlapping with the third region and a fifth region that is wider than the fourth region; the power supply line has a region overlapping with a first conductive layer having a region functioning as a gate electrode of the second transistor; the power supply line has a region overlapping with a second conductive layer having a region functioning as a gate electrode of the third transistor; the power supply line has a region that contacts the semiconductor layer through an opening, The fifth region has a region overlapping with the opening.

5. In any one of claims 1 to 4, In the display device, each of the first to third transistors is an n-channel transistor.

Images