Working method of display device

Abstract

Provided is a display device capable of correcting the threshold voltage of a driving transistor without correcting image data. A display device is provided, the display device comprising a pixel having a driving transistor, a display element and a storage circuit, and a correction data generation circuit. One of the source and the drain of the driving transistor is electrically connected to an electrode of the display element, and the gate of the driving transistor is electrically connected to the storage circuit. During a first period, the correction data generation circuit generates correction data as data for correcting the threshold voltage of the driving transistor. During a second period, the first data is written into the storage circuit. During a third period, by supplying the second data to the pixel, third data is generated as data obtained by adding the second data to the first data. During a fourth period, an image corresponding to the third data is displayed by the display element.

Description

Technical Field

[0001] One embodiment of the present invention relates to a display device and an operating method thereof.

[0002] Note that one embodiment of the present invention is not limited to the above-mentioned technical field. The technical field of one embodiment of the invention disclosed in this specification, etc., relates to an object, method or manufacturing method. In addition, one embodiment of the present invention relates to a process, a machine, a product or a composition of matter. Therefore, more specifically, as examples of the technical field of one embodiment of the present invention disclosed in this specification, semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, camera devices, driving methods of these devices or manufacturing methods of these devices can be cited.

[0003] Note that in this specification and the like, a semiconductor device refers to any device that can operate by utilizing semiconductor characteristics. A transistor and a semiconductor circuit are one form of a semiconductor device. In addition, a storage device, a display device, a camera device, and an electronic device may include a semiconductor device. Background Art

[0004] In a display device using a light-emitting element as a display element, the brightness of light emitted from the display element easily reflects the unevenness of the threshold voltage of the transistor that controls the current supplied to the display element according to the image data, that is, the driving transistor. Patent document 1 describes a display device that detects the threshold voltage and mobility of the driving transistor from the source potential of the driving transistor and corrects the image data based on the threshold voltage and the mobility. Thus, the threshold voltage of the driving transistor can be corrected. Therefore, it is possible to suppress the uneven threshold voltage of the driving transistor between each pixel from affecting the brightness of the light emitted from the display element.

[0005] [Prior technical literature]

[0006] [Patent Document]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2009-265459 Summary of the invention

[0008] Technical problem to be solved by the invention

[0009] When correcting the image data to correct the threshold voltage of the driving transistor, it is necessary to increase the dynamic range of the image data (the difference between the maximum and minimum values ​​of the potential that the signal corresponding to the image data can take). Thus, for example, if the brightness of the light emitted from the display element is increased by 1 gray level, the increase in the potential of the signal corresponding to the image data becomes larger, so that the quality of the displayed image is sometimes reduced. In addition, the display device needs to be provided with a data driving circuit with high voltage resistance, and sometimes the manufacturing cost of the display device is increased. Furthermore, the output potential of the data driving circuit increases, which may lead to an increase in the power consumption of the display device.

[0010] One of the purposes of one embodiment of the present invention is to provide a display device capable of correcting the threshold voltage of a driving transistor without correcting image data. Furthermore, one of the purposes of one embodiment of the present invention is to provide a display device capable of displaying high-quality images. Furthermore, one of the purposes of one embodiment of the present invention is to provide an inexpensive display device. Furthermore, one of the purposes of one embodiment of the present invention is to provide a low-power display device. Furthermore, one of the purposes of one embodiment of the present invention is to provide a display device capable of displaying high-brightness images. Furthermore, one of the purposes of one embodiment of the present invention is to provide a small display device. Furthermore, one of the purposes of one embodiment of the present invention is to provide a display device having a large display area. Furthermore, one of the purposes of one embodiment of the present invention is to provide a high-reliability display device. Furthermore, one of the purposes of one embodiment of the present invention is to provide a novel display device. Furthermore, one of the purposes of one embodiment of the present invention is to provide a novel semiconductor device, etc.

[0011] Furthermore, one of the purposes of one embodiment of the present invention is to provide a method for operating a display device capable of correcting the threshold voltage of a driving transistor without correcting image data. Furthermore, one of the purposes of one embodiment of the present invention is to provide a method for operating a display device capable of displaying high-quality images. Furthermore, one of the purposes of one embodiment of the present invention is to provide a method for operating an inexpensive display device. Furthermore, one of the purposes of one embodiment of the present invention is to provide a method for operating a low-power display device. Furthermore, one of the purposes of one embodiment of the present invention is to provide a method for operating a display device capable of displaying high-brightness images. Furthermore, one of the purposes of one embodiment of the present invention is to provide a method for operating a small display device. Furthermore, one of the purposes of one embodiment of the present invention is to provide a method for operating a display device having a large display area. Furthermore, one of the purposes of one embodiment of the present invention is to provide a method for operating a high-reliability display device. Furthermore, one of the purposes of one embodiment of the present invention is to provide a novel method for operating a display device. Furthermore, one of the purposes of one embodiment of the present invention is to provide a novel method for operating a semiconductor device, etc.

[0012] Note that the recording of these purposes does not prevent the existence of other purposes. In addition, one mode of the present invention does not need to achieve all of the above purposes. In addition, purposes other than these purposes are naturally clear from the description of the specification, drawings, claims, etc., and purposes other than the above can be derived from the description of the specification, drawings, claims, etc.

[0013] Solutions to technical problems

[0014] One embodiment of the present invention is a method for operating a display device, the display device including a pixel having a transistor, a display element and a storage circuit, and a correction data generation circuit, wherein one of a source and a drain of the transistor is electrically connected to an electrode of the display element, and a gate of the transistor is electrically connected to the storage circuit, wherein during a first period, the correction data generation circuit generates correction data as data for correcting a threshold voltage of the transistor, during a second period, the first data is written into the storage circuit, during a third period, third data as data obtained by adding the second data to the first data is generated by supplying the second data to the pixel, and during a fourth period, an image corresponding to the third data is displayed by the display element.

[0015] Furthermore, in the above-described embodiment, during the first period, the correction data generation circuit may generate correction data and then supply a potential corresponding to the correction data to the back gate of the transistor.

[0016] In the above aspect, during the first period, a current may be caused to flow through the transistor, and the correction data generation circuit may generate correction data corresponding to the current.

[0017] In the above aspect, the correction data generation circuit may generate the correction data so that the current flowing through the transistor becomes equal to or less than a certain value during the first period.

[0018] In the above-described embodiment, current may not flow through the display element in the first period, but current may flow through the display element in the fourth period.

[0019] In addition, one embodiment of the present invention is a method for operating a display device, the display device including a pixel having a first transistor, a second transistor, a third transistor, a capacitor and a display element, and a correction data generation circuit, wherein one of the source and the drain of the first transistor is electrically connected to one electrode of the capacitor, one of the source and the drain of the second transistor is electrically connected to the other electrode of the capacitor, the other electrode of the capacitor is electrically connected to the gate of the third transistor, and one of the source and the drain of the third transistor is electrically connected to one electrode of the display element, in a first period, the correction data generation circuit generates correction data as data for correcting a threshold voltage of the third transistor, in a second period, a first potential is supplied to the other electrode of the capacitor, in a third period, a second potential is supplied to one electrode of the capacitor so that the potential of the other electrode of the capacitor becomes a third potential, and in a fourth period, a current corresponding to the third potential flows through the display element.

[0020] Furthermore, in the above aspect, during the first period, the correction data generation circuit may generate correction data and then supply a potential corresponding to the correction data to the back gate of the third transistor.

[0021] In addition, in the above-mentioned method, that is, the working method of the display device, the pixel also includes a fourth transistor, and one of the source and the drain of the fourth transistor is electrically connected to one of the source and the drain of the third transistor. During the first period, the fourth transistor can also be turned on so that current flows through the third and fourth transistors, and correction data corresponding to the current is generated by the correction data generation circuit.

[0022] In the above aspect, the correction data generation circuit may generate the correction data in the first period so that the current flowing through the third transistor becomes equal to or less than a certain value.

[0023] Furthermore, in the above embodiment, the fourth transistor may be turned off during the fourth period.

[0024] In addition, in the above method, the second transistor may also include a metal oxide in the channel formation region, and the metal oxide includes In, Zn, and M (M is Al, Ti, Ga, Ge, Sn, Y, Zr, La, Ce, Nd, or Hf).

[0025] In the above embodiment, the display element may be an organic EL element.

[0026] Effects of the Invention

[0027] According to one embodiment of the present invention, a display device capable of correcting the threshold voltage of a driving transistor without correcting image data can be provided. In addition, a display device capable of displaying high-quality images can be provided. In addition, an inexpensive display device can be provided. In addition, a low-power display device can be provided. In addition, a display device capable of displaying high-brightness images can be provided. In addition, a small display device can be provided. In addition, a display device with a large display area can be provided. In addition, a high-reliability display device can be provided. In addition, a novel display device can be provided. In addition, a novel semiconductor device can be provided, etc.

[0028] In addition, a method for operating a display device capable of correcting the threshold voltage of a driving transistor without correcting image data may be provided. In addition, a method for operating a display device capable of displaying high-quality images may be provided. In addition, a method for operating an inexpensive display device may be provided. In addition, a method for operating a low-power display device may be provided. In addition, a method for operating a display device capable of displaying high-brightness images may be provided. In addition, a method for operating a small display device may be provided. In addition, a method for operating a display device having a large display area may be provided. In addition, a method for operating a high-reliability display device may be provided. In addition, a novel method for operating a display device may be provided. In addition, a novel method for operating a semiconductor device or the like may be provided.

[0029] Note that the description of these effects does not prevent the existence of other effects. In addition, one mode of the present invention does not necessarily need to have all of the above effects. In addition, effects other than the above can be derived from the description of the specification, drawings, claims, etc.

[0030] BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a circuit diagram showing a structural example of a pixel.

[0032] Figure 2 : is a timing chart showing an example of the operation method of a pixel.

[0033] Figure 3A and Figure 3B is a circuit diagram showing an example of an operating method of a pixel.

[0034] Figure 4A and Figure 4B is a circuit diagram showing an example of an operating method of a pixel.

[0035] Figure 5A and Figure 5B is a circuit diagram showing an example of an operating method of a pixel.

[0036] Figure 6 is a circuit diagram showing an example of an operating method of a pixel.

[0037] Figure 7 This is a diagram showing an example of the operation of the display device.

[0038] Fig. 8A and Figure 8B is a block diagram showing a structural example of a display device.

[0039] Fig. 9 is a circuit diagram showing a structural example of a pixel.

[0040] Fig. 10A and Fig. 10B is a circuit diagram showing a structural example of a pixel.

[0041] Fig.11A and Fig. 11B is a circuit diagram showing a structural example of a pixel.

[0042] Fig.12 : is a timing chart showing an example of the operation method of a pixel.

[0043] Fig.13 : is a timing chart showing an example of the operation method of a pixel.

[0044] Fig.14A and Fig. 14B is a diagram showing a structural example of a display device.

[0045] Fig.15A and Fig. 15B is a diagram showing a structural example of a touch panel.

[0046] Fig.16A and Fig. 16B is a diagram showing a structural example of a display device.

[0047] Fig.17 is a diagram showing a structural example of a display device.

[0048] Fig.18 is a diagram showing a structural example of a display device.

[0049] Fig.19A1 , Fig.19A2 , Figure 19B1 , Figure 19B2 , Fig.19C1 and Fig.19C2 is a diagram showing a structural example of a transistor.

[0050] Fig.20A1 , Fig.20A2 , Fig.20A3 , Fig.20B1 , Figure 20B2 , Fig.20C1 and Fig.20C2 is a diagram showing a structural example of a transistor.

[0051] Fig.21A , Fig. 21B , Fig. 21C , Fig.21D , Fig.21E and Fig.21F is a diagram showing an example of an electronic device.

[0052] Modes for Carrying Out the Invention

[0053] The embodiments are described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the following description, and a person skilled in the art can easily understand that the method and details can be transformed into various forms without departing from the purpose and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the contents described in the embodiments shown below.

[0054] Note that in the invention structure described below, the same symbols are used in different drawings to represent the same parts or parts with the same function, and repeated description is omitted. In addition, when representing parts with the same function, the same hatching is sometimes used without special additional symbols.

[0055] In addition, for ease of understanding, the position, size, range, etc. of each component shown in the drawings may not represent its actual position, size, range, etc. Therefore, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings.

[0056] In addition, the words "film" and "layer" may be interchanged depending on the situation or state. For example, "conductive layer" may sometimes be converted into "conductive film". In addition, "insulating film" may sometimes be converted into "insulating layer".

[0057] In this specification, etc., metal oxide refers to an oxide of a metal in a broad sense. Metal oxides are classified into oxide insulators, oxide conductors (including transparent oxide conductors), and oxide semiconductors (Oxide Semiconductor, also referred to as OS), etc. For example, when a metal oxide is used in a semiconductor layer of a transistor, the metal oxide is sometimes referred to as an oxide semiconductor. In other words, "OS FET" refers to a transistor containing a metal oxide or an oxide semiconductor.

[0058] In this specification and the like, a metal oxide containing nitrogen may be referred to as a metal oxide (metal oxide). In addition, a metal oxide containing nitrogen may also be referred to as a metal oxynitride (metal oxynitride).

[0059] (Implementation Method 1)

[0060] In this embodiment, a display device and an operating method thereof according to one embodiment of the present invention are described with reference to the drawings.

[0061] One embodiment of the present invention is a method for operating a display device capable of correcting the threshold voltage of a driving transistor without correcting the image data supplied to a pixel. According to one embodiment of the present invention, the threshold voltage of a driving transistor can be corrected without increasing the dynamic range of the image data (the difference between the maximum and minimum values ​​of the potential that a signal corresponding to the image data can take). Thus, the following situation can be suppressed: when the threshold voltage of the driving transistor is corrected, for example, the brightness of the light emitted from the display element is increased by 1 gray level, and the increase in the potential of the signal corresponding to the image data becomes larger. Therefore, the brightness of the light emitted from the display element can be precisely controlled, so that the display device can display a high-quality image. In addition, the data driving circuit provided in the display device does not need to have a high voltage resistance, so that the price of the display device will also become low. Furthermore, the output potential of the data driving circuit can be suppressed from increasing, thereby reducing the power consumption of the display device.

[0062] In addition, a pixel in a display device according to one embodiment of the present invention includes a storage circuit. The storage circuit can be written with image correction data, for example, for correcting image data. Thus, for example, image processing such as noise removal can be performed inside the pixel. Therefore, compared with a case where image data is directly corrected using an operation circuit or the like provided outside the pixel to perform image processing, the operation processing may become simpler. Therefore, the power consumption of the display device can be reduced.

[0063] In addition, image data can be written to the above-mentioned storage circuit. By supplying second image data to pixels including the storage circuit after writing the first image data to the storage circuit, the display device can display an image corresponding to the first image data and an image corresponding to the second image data superimposed. The brightness of the superimposed image can be the sum of the brightness presented by the first image data and the brightness presented by the second image data. Therefore, the display device can display an image corresponding to image data represented by a signal whose potential is higher than the potential that can be generated by the data driving circuit. As described above, compared with the case where the image data is not superimposed but only an image corresponding to one image data is displayed, the display device can display a high-brightness image. In addition, a data driving circuit with high voltage resistance is not required, and the price of the display device will also become low. Furthermore, the output potential of the data driving circuit can be suppressed from increasing, thereby reducing the power consumption of the display device.

[0064] <Pixel Structure Example 1>

[0065] Figure 1 A structural example of a pixel 10 that can be used as a pixel of a display device according to one embodiment of the present invention is shown. The pixel 10 includes a transistor 11, a transistor 12, a transistor 13, a transistor 14, a transistor 15, a display element 20, a capacitor 21, a capacitor 22, and a capacitor 23. Here, the transistor 13 includes not only a gate but also a back gate.

[0066] One of the source and drain of the transistor 11 is electrically connected to one electrode of the capacitor 21. One of the source and drain of the transistor 12 is electrically connected to the gate of the transistor 13. The gate of the transistor 13 is electrically connected to the other electrode of the capacitor 21. The other electrode of the capacitor 21 is electrically connected to one electrode of the capacitor 22.

[0067] One of the source and drain of the transistor 13 is electrically connected to one of the source and drain of the transistor 14. One of the source and drain of the transistor 14 is electrically connected to one electrode of the display element 20. One electrode of the display element 20 is electrically connected to the other electrode of the capacitor 22. The other electrode of the capacitor 22 is electrically connected to one electrode of the capacitor 23.

[0068] The back gate of the transistor 13 is electrically connected to one of the source and the drain of the transistor 15. One of the source and the drain of the transistor 15 is electrically connected to the other electrode of the capacitor 23.

[0069] Here, a node at which one of the source and drain of the transistor 11 and one electrode of the capacitor 21 are electrically connected is referred to as a node ND1. In addition, a node at which one of the source and drain of the transistor 12, the gate of the transistor 13, the other electrode of the capacitor 21, and one electrode of the capacitor 22 are electrically connected is referred to as a node ND2. In addition, a node at which one of the source and drain of the transistor 13, one of the source and drain of the transistor 14, one electrode of the display element 20, the other electrode of the capacitor 22, and one electrode of the capacitor 23 are electrically connected is referred to as a node ND3. Furthermore, a node at which the back gate of the transistor 13, one of the source and drain of the transistor 15, and the other electrode of the capacitor 23 are electrically connected is referred to as a node ND4.

[0070] The gate of transistor 11 and the gate of transistor 14 are electrically connected to wiring 31. The gate of transistor 12 is electrically connected to wiring 32. The gate of transistor 15 is electrically connected to wiring 35. The other of the source and the drain of transistor 11 is electrically connected to wiring 41. The other of the source and the drain of transistor 12 is electrically connected to wiring 42. The other of the source and the drain of transistor 15 is electrically connected to wiring 45. The other of the source and the drain of transistor 13 is electrically connected to wiring 53. The other of the source and the drain of transistor 14 is electrically connected to wiring 54. The other electrode of display element 20 is electrically connected to wiring 50.

[0071] Wiring 31, wiring 32, and wiring 35 are used as scan lines. Turning on and off of transistors 11 and 14 can be controlled by a signal supplied to the gate of transistor 11 and the gate of transistor 14 through wiring 31. Turning on and off of transistor 12 can be controlled by a signal supplied to the gate of transistor 12 through wiring 32. Turning on and off of transistor 15 can be controlled by a signal supplied to the gate of transistor 15 through wiring 35.

[0072] The wiring 41 , the wiring 42 , and the wiring 45 are used as data lines. Desired data is supplied to the pixel 10 through the wiring 41 , the wiring 42 , and the wiring 45 .

[0073] The wiring 50, the wiring 53, and the wiring 54 are used as power supply lines. For example, a low potential can be supplied as a power supply potential to the wiring 50 and the wiring 54. For example, a high potential can be supplied as a power supply potential to the wiring 53.

[0074] The memory circuit MEM is composed of a transistor 12 and a capacitor 21. By turning on the transistor 12, data supplied to the pixel 10 through the wiring 42 is written to the node ND2 provided in the memory circuit MEM. By turning off the transistor 12, the data written to the node ND2 is retained. In addition, the memory circuit MEM may include elements other than the transistor 12 and the capacitor 21.

[0075] In addition, by turning on the transistor 15, data supplied to the pixel 10 through the wiring 45 is written to the node ND4. By turning off the transistor 15, the data written to the node ND4 is retained. The data written to the node ND4 may be data for correcting the threshold voltage of the transistor 13.

[0076] In this specification and the like, data used to correct the threshold voltage of a transistor is referred to as threshold voltage correction data or simply correction data.

[0077] By turning on the transistor 11, data supplied to the pixel 10 through the wiring 41 is written into the node ND1. The data written into the node ND1 may be image data, and an image corresponding to the image data may be displayed by the display element 20.

[0078] Here, when data is written to the node ND1 so that the potential of the node ND1 changes, the potential of the node ND2 changes due to capacitive coupling. Thus, the potential of the node ND2 depends on the potential of the node ND1. Therefore, for example, by writing the image data to the node ND1 after writing the data used to correct the image data to the node ND2, the potential of the node ND2 becomes the potential corresponding to the corrected image data. Thus, image processing such as noise removal can be performed inside the pixel 10. Therefore, compared with the case where the image data is directly corrected for image processing using an operation circuit or the like provided outside the pixel 10, the operation processing may become simple. Therefore, the power consumption of the display device can be reduced.

[0079] In this specification and the like, data used to correct image data is referred to as image correction data.

[0080] In addition, image data may also be written to the node ND2. For example, by writing the second image data to the node ND1 after writing the first image data to the node ND2, the display element 20 displays an image in which an image corresponding to the first image data and an image corresponding to the second image data are superimposed. The brightness of the superimposed image may be the sum of the brightness presented by the first image data and the brightness presented by the second image data. Therefore, compared with the case where the image data is not superimposed and only an image corresponding to one image data is displayed, the display device can display a high-brightness image.

[0081] Note that the data written to the node ND2 and the like may sometimes be attenuated due to factors on the transmission path, and therefore it is preferable to generate the data in consideration of this attenuation.

[0082] The transistor 13 is used as a driving transistor that controls the current flowing through the display element 20 according to the potential of its gate, that is, the potential of the node ND2. That is, the transistor 13 has a function of making the current value flowing through the display element 20 correspond to the image data supplied to the pixel 10 when the display element 20 displays an image.

[0083] By using a transistor with an extremely low off-state current as the transistor 12, the potential of the node ND2 can be maintained for a long time, and thus the pixel 10 can maintain the potential written to the node ND2 for a long time. In addition, by using a transistor with an extremely low off-state current as the transistor 15, the potential of the node ND4 can be maintained for a long time, and thus the pixel 10 can maintain the potential written to the node ND4 for a long time. As a transistor with an extremely low off-state current, for example, a transistor using a metal oxide for a channel formation region (hereinafter referred to as an OS transistor) can be used.

[0084] Note that in addition to transistors 12 and 15, OS transistors can also be applied to other transistors constituting pixel 10. In addition, transistors containing silicon in the channel formation region (hereinafter referred to as Si transistors) can also be used as transistors 12 and 15. Alternatively, OS transistors are used as some of the transistors in transistors 11 to 15, and Si transistors are used as other transistors. Examples of the above-mentioned Si transistors include: transistors containing amorphous silicon, transistors containing crystalline silicon (typically, low-temperature polysilicon), transistors containing single crystal silicon, etc.

[0085] As a semiconductor material for OS transistors, metal oxides with an energy gap of 2eV or more, preferably 2.5eV or more, and more preferably 3eV or more can be used. Typical examples include oxide semiconductors containing indium, such as CAAC-OS (C-Axis Aligned Crystalline Oxide Semiconductor) or CAC-OS (Cloud-Aligned Composite Oxide Semiconductor) mentioned later. The atoms that make up the crystal in CAAC-OS are stable, and it is suitable for transistors that value reliability. CAC-OS exhibits high mobility characteristics and is suitable for transistors that are driven at high speeds.

[0086] OS transistors have a large bandgap and exhibit extremely low off-state current characteristics. Unlike Si transistors, OS transistors do not experience impact ionization, avalanche breakdown, short channel effects, etc., so they can form highly reliable circuits.

[0087] As a semiconductor layer in the OS transistor, for example, a film represented by "In-M-Zn oxide" containing indium, zinc and M (aluminum, titanium, gallium, germanium, yttrium, zirconium, lanthanum, cerium, tin, neodymium or hafnium, etc.) can be used.

[0088] When the oxide semiconductor constituting the semiconductor layer is an In-M-Zn oxide, the atomic ratio of the metal element of the sputtering target used to form the In-M-Zn oxide film preferably satisfies In≥M and Zn≥M. The atomic ratio of the metal element of such a sputtering target is preferably In:M:Zn=1:1:1, In:M:Zn=1:1:1.2, In:M:Zn=3:1:2, In:M:Zn=4:2:3, In:M:Zn=4:2:4.1, In:M:Zn=5:1:6, In:M:Zn=5:1:7, In:M:Zn=5:1:8, etc. Note that the atomic ratio of the semiconductor layer formed may vary within the range of ±40% of the atomic ratio of the metal element in the above-mentioned sputtering target.

[0089] As the semiconductor layer, an oxide semiconductor with a low carrier density can be used. For example, an oxide semiconductor with a carrier density of 1×10 17 / cm 3 Below, preferably 1×10 15 / cm 3 Below, more preferably 1×10 13 / cm 3 Below, more preferably 1×10 11 / cm 3 Below, more preferably less than 1×10 10 / cm 3 And 1×10 -9 / cm 3 The above oxide semiconductors are referred to as high-purity intrinsic or substantially high-purity intrinsic oxide semiconductors. Since the defect state density of the oxide semiconductor is low, it can be said that the oxide semiconductor has stable characteristics.

[0090] Note that the present invention is not limited to the above description, and a material having an appropriate composition can be used according to the desired semiconductor characteristics and electrical characteristics (field effect mobility, threshold voltage, etc.) of the transistor. In addition, it is preferred to appropriately set the carrier density, impurity concentration, defect density, atomic ratio of metal elements to oxygen, interatomic distance, density, etc. of the semiconductor layer to obtain the desired semiconductor characteristics of the transistor.

[0091] When the oxide semiconductor constituting the semiconductor layer contains silicon or carbon, which is one of the Group 14 elements, oxygen vacancies increase, which causes the semiconductor layer to become n-type. Therefore, the concentration of silicon or carbon in the semiconductor layer (the concentration measured by secondary ion mass spectrometry) is set to 2×10 18 atoms / cm 3 Below, preferably 2×10 17 atoms / cm 3 the following.

[0092] In addition, when an alkali metal or alkaline earth metal is bonded to an oxide semiconductor, carriers are generated, which increases the off-state current of the transistor. Therefore, the concentration of the alkali metal or alkaline earth metal in the semiconductor layer (the concentration measured by secondary ion mass spectrometry) is set to 1×10 18 atoms / cm 3 Below, preferably 2×10 16 atoms / cm 3 the following.

[0093] In addition, when the oxide semiconductor constituting the semiconductor layer contains nitrogen, electrons are generated as carriers, the carrier density increases, and it is easy to become n-type. As a result, the transistor using the oxide semiconductor containing nitrogen is easy to become normally-on. Therefore, the nitrogen concentration of the semiconductor layer (the concentration measured by secondary ion mass spectrometry) is preferably 5×10 18 atoms / cm 3 the following.

[0094] In addition, the semiconductor layer may also have a non-single-crystal structure, for example. The non-single-crystal structure includes, for example, a crystalline CAAC-OS with a c-axis orientation, a polycrystalline structure, a microcrystalline structure, or an amorphous structure. Among the non-single-crystal structures, the amorphous structure has the highest defect state density, while the CAAC-OS has the lowest defect state density.

[0095] The oxide semiconductor film with an amorphous structure has, for example, a disordered atomic arrangement and no crystalline component. Alternatively, the oxide semiconductor film with an amorphous structure has, for example, a completely amorphous structure and no crystalline part.

[0096] In addition, the semiconductor layer may be a mixed film having two or more of an amorphous structure region, a microcrystalline structure region, a polycrystalline structure region, a CAAC-OS region, and a single crystal structure region. The mixed film may have a single layer structure or a stacked layer structure including two or more of the above regions.

[0097] The display element 20 may use a light emitting element, for example. For example, the light emitting element may use an organic electroluminescent (EL) element, an inorganic EL element, or a quantum dot light emitting diode (QDLED). In addition, the light emitting element may use an LED such as a Micro LED.

[0098] By using Micro LED as the display element 20, the power consumption of the display device of one embodiment of the present invention can be reduced. In addition, the display device of one embodiment of the present invention can be made thinner and lighter. In addition, the display device using Micro LED as the display element 20 has high contrast and wide viewing angle, and can therefore display high-quality images. In addition, when Micro LED is used as the display element 20, the area of ​​the light emitting region is preferably 10000 μm 2 Below, more preferably 1000 μm 2 Below, more preferably 700 μm 2 the following.

[0099] <Example 1 of how pixels work>

[0100] Figure 2 It shows that Figure 1 The timing diagram of an example of the operation method of the pixel 10 of the structure shown in FIG. Figure 2 10 , operations of the pixel 10 in the period T01 , the period T11 , the period T12 , the period T13 , the period T14 , the period T21 , and the period T22 are described respectively. Figures 3A to 6 Show Figure 2 The turning on and off of the transistors, the potential of the wiring and nodes, and the direction of the current in each period are shown. Figures 2 to 6 In the figure, "H" indicates a high potential, and "L" indicates a low potential.

[0101] In this specification, etc., a high potential refers to a potential higher than a low potential. For example, a high potential refers to a potential that turns an n-channel transistor on, and a low potential refers to a potential that turns an n-channel transistor off. In addition, a high potential refers to a potential that turns a p-channel transistor off, and a low potential refers to a potential that turns a p-channel transistor on. For example, a high potential may be a positive potential, and a low potential may be a ground potential or a negative potential.

[0102] Assume that Figures 2 to 6 The operation method of the pixel 10 will be described in the case where the wiring 50 is supplied with a low potential, the wiring 53 is supplied with a high potential, and the wiring 54 is supplied with a potential V0. The potential V0 is lower than the potential of the wiring 53.

[0103] In addition, assuming that Figures 2 to 6 The operation method of the pixel 10 is described below with reference to the case where the transistors 11 to 15 are all n-channel transistors. By appropriately reversing the magnitude relationship of the potentials, etc., it is also possible to refer to the case where some or all of the transistors 11 to 15 are p-channel transistors. Figures 2 to 6 The working method shown.

[0104] exist Figures 3A to 6 In order to clearly indicate on or off, transistors other than transistor 13 are indicated by switch symbols, and wiring 31, wiring 32, and wiring 35 are not indicated. In addition, wirings and nodes whose potentials are different from those in the previous period are indicated by surrounding symbols with solid lines.

[0105] During period T01 (ref. Figure 2 and Figure 3A ), the potential of wiring 31, the potential of wiring 32 and the potential of wiring 35 are set to a high potential, and then the potential of wiring 42 is set to potential V0 and the potential of wiring 45 is set to potential V1. As a result, transistors 11, 12, 14 and 15 are turned on, the potential of node ND2 and the potential of node ND3 become potential V0, and the potential of node ND4 becomes potential V1. Through the above operation, current flows from wiring 53 through transistor 13 to wiring 54. This current is detected by a circuit provided outside pixel 10. In addition, the potential of wiring 42 may not be equal to the potential V0 which is the potential of wiring 54. In addition, the potential of wiring 41 may be any potential, but its potential is described as 0V below.

[0106] Here, the potential V0 is preferably a potential that does not cause current to flow through the display element 20. For example, the value of the potential V0 is preferably set in such a manner that the voltage applied to the display element 20 becomes less than the threshold voltage of the display element 20. For example, the potential V0 is preferably a low potential equal to the potential of the wiring 50. Thus, the current flowing through the transistor 13 can be accurately detected. In addition, abnormal display can be suppressed.

[0107] During period T11 (ref. Figure 2 and Figure 3B ), the potential of wiring 45 is set to the potential calculated based on the current detected in period T01, that is, the potential Vc. As a result, the potential of node ND4 becomes the potential Vc, and the potential of the back gate of transistor 13 becomes the potential Vc. The potential Vc is, for example, a potential at which the current flowing through transistor 13 becomes less than a certain value when transistor 14 is turned on. For example, the potential Vc is calculated in such a way that the threshold voltage of transistor 13 becomes the difference between the potential of node ND2 in period T11 and the potential of node ND3. Figure 3B In the illustrated case, since the difference between the potential of the node ND2 and the potential of the node ND3 is 0 V, the potential Vc can be calculated so that the threshold voltage of the transistor 13 becomes 0 V, for example.

[0108] Through the above operation, the threshold voltage of the transistor 13 as the driving transistor is corrected. Therefore, the period T01 and the period T11 can be called the threshold voltage correction period. Here, it is preferable to increase the potential V1 as much as possible, thereby increasing the current flowing through the transistor 13 during the period T01, so that the threshold voltage can be corrected with high accuracy.

[0109] During period T12 (ref. Figure 2 and Figure 4A ), the potential of wiring 35 is set to a low potential. As a result, transistor 15 becomes off, and the potential of node ND4 is maintained at potential Vc. Then, the potential of wiring 42 is set to a potential corresponding to the first data, that is, potential VD1. As a result, the potential of node ND2 becomes potential VD1, and the first data is written into the storage circuit MEM. Here, the first data may be image correction data or image data. In addition, the potential of wiring 45 may be any potential.

[0110] In short, the period T12 can be called a first data writing period.

[0111] During period T13 (ref. Figure 2 and Figure 4B ), the potential of wiring 32 is set to a low potential. As a result, transistor 12 becomes off and the potential of node ND2 is maintained. Then, the potential of wiring 41 is set to a potential corresponding to the second data, that is, potential VD2, so that the potential of node ND1 changes from 0V to potential VD2. In other words, the potential of node ND1 is increased by potential VD2. Here, because node ND2 is in a floating state, when the capacitive coupling coefficient of node ND2 is 1, the potential of node ND2 becomes potential "VD1+VD2". Through the above operation, pixel 10 is supplied with the second data, and the data held by the storage circuit MEM becomes the third data which is the data obtained by adding the second data to the first data. Here, the second data can be image data. In addition, the potential of wiring 42 can be any potential.

[0112] In this specification and the like, when both the first data and the second data are image data, the first data may be referred to as first image data and the second data may be referred to as second image data.

[0113] In short, the period T13 can be called a second data writing period.

[0114] During period T14 (ref. Figure 2 and Figure 5A), the potential of wiring 31 is set to a low potential. As a result, transistors 11 and transistors 14 are turned off. Since transistor 11 is turned off, the potential of node ND1 is maintained. In addition, since transistor 14 is turned off, the potential of node ND3 rises accordingly with the potential of node ND2. As a result, a current corresponding to the potential difference between node ND3 and wiring 50 flows through display element 20. Therefore, an image corresponding to the potential of node ND2, that is, an image corresponding to the third data is displayed by display element 20. For example, in a case where the data corresponding to potential VD1 is image correction data and the data corresponding to potential VD2 is image data, an image corresponding to the corrected image data is displayed by display element 20. In addition, in a case where the data corresponding to potential VD1 is first image data and the data corresponding to potential VD2 is second image data, an image corresponding to the first image data and an image corresponding to the second image data are superimposed on each other and displayed by display element 20.

[0115] In short, the period T14 can be called a read period of the third data.

[0116] During period T21 (ref. Figure 2 and Figure 5B ), the potential of wiring 31 is set to a high potential. As a result, transistors 11 and 14 are turned on. Then, the potential of wiring 41 is set to a potential corresponding to the second data, that is, potential VD2'. Because transistor 11 is turned on and the potential of wiring 41 becomes potential VD2', when the capacitive coupling coefficient of node ND2 is 1, the potential of node ND2 becomes potential "VD1+VD2'". Through the above operation, the pixel 10 is supplied with the second data, and the data held by the storage circuit MEM becomes the third data which is the data obtained by adding the second data to the first data. Here, the potential VD2' can be a potential different from the potential VD2. For example, it can be a potential corresponding to the image data of the next frame after the image data is supplied to the pixel 10 during period T13.

[0117] Furthermore, since the transistor 14 is turned on, the potential of the node ND3 becomes the potential V0 which is the potential of the wiring 54. Thus, current does not flow through the display element 20.

[0118] During period T22 (ref. Figure 2 and Figure 6), the potential of wiring 31 is set to a low potential. As a result, transistors 11 and 14 are turned off. Since transistor 11 is turned off, the potential of node ND1 is maintained. In addition, since transistor 14 is turned off, the potential of node ND3 rises accordingly with the potential of node ND2. As a result, a current corresponding to the potential difference between node ND3 and wiring 50 flows through display element 20. Therefore, an image corresponding to the potential of node ND2, that is, an image corresponding to the third data, is displayed by display element 20.

[0119] In short, period T21 is the writing period of the second data, and period T22 is the reading period of the third data. That is to say, period T21 and period T13 are the periods for performing the same operation, and period T22 and period T14 are the periods for performing the same operation. In addition, it can be said that one frame period is composed of period T13 and period T14, and the next frame period is composed of period T21 and period T22.

[0120] Here, between the period T14 and the period T21, neither the potential Vc corresponding to the threshold voltage correction data is supplied to the node ND4 nor the potential VD1 corresponding to the first data is supplied to the node ND2. As described above, an OS transistor or the like can be used as the transistor 15 to hold the potential of the node ND4 for a long time, and an OS transistor or the like can be used as the transistor 12 to hold the potential of the node ND2 for a long time. Therefore, it is not necessary to supply the potential Vc to the node ND4 and the potential VD1 to the node ND2 during each frame period, thereby enabling the display device of one embodiment of the present invention to operate at a high speed.

[0121] Through the above operation, a display device of one embodiment of the present invention can correct the threshold voltage of transistor 13 as a driving transistor without correcting the image data supplied to pixel 10. Thus, the threshold voltage of transistor 13 can be corrected without increasing the dynamic range of image data (the difference between the maximum and minimum values ​​of the potential that the signal corresponding to the image data can take). Thus, the following situation can be suppressed: when the threshold voltage of transistor 13 is corrected, for example, the brightness of the light emitted from the display element is increased by 1 gray level, and the increase in the potential of the signal corresponding to the image data becomes larger. Therefore, the brightness of the light emitted from the display element can be precisely controlled, thereby enabling the display element 20 to display a high-quality image. In addition, the data driving circuit, which is a circuit having the function of generating image data, does not need to have a high voltage resistance, thereby the price of the display device will also become low. Furthermore, the output potential of the data driving circuit can be suppressed from increasing, thereby reducing the power consumption of the display device.

[0122] In addition, the pixel 10 includes a storage circuit MEM in which the first data can be written. By supplying the image data as the second data to the pixel 10 after writing the image correction data as the first data to the storage circuit MEM, image processing such as noise processing can be performed inside the pixel 10. Therefore, compared with the case where the image data is directly corrected using an operation circuit or the like provided outside the pixel 10 to perform image processing, the operation processing can be simplified. Therefore, the power consumption of the display device of one embodiment of the present invention can be reduced.

[0123] In addition, by writing the first image data as the first data into the storage circuit MEM and then supplying the second image data as the second data to the pixel 10, the display element 20 can display an image corresponding to the first image data and an image corresponding to the second image data superimposed. The brightness of the superimposed image can be the sum of the brightness presented by the first image data and the brightness presented by the second image data. Therefore, the display element 20 can display an image corresponding to the image data represented by a signal whose potential is higher than the potential that can be generated by the data driving circuit with an image generation function. As described above, compared with the case where the image data is not superimposed but only one image data corresponding to the image is displayed, the display element 20 can display a high-brightness image. In addition, a data driving circuit with high voltage resistance is not required, and the price of the display device will also become low. Furthermore, the output potential of the data driving circuit can be suppressed from increasing, thereby reducing the power consumption of the display device.

[0124] Here, the image corresponding to the first image data and the image corresponding to the second image data may be the same as or different from each other. Figure 7 The case where the image P1 corresponding to the first image data includes pictures and text and the image P2 corresponding to the second image data includes only text is shown. In this case, by overlapping the image P1 and the image P2, the brightness of the text can be increased, for example, the text can be emphasized. In addition, the image P2 is not limited to an image including only text, and the image P1 is not limited to an image including pictures and text.

[0125] In addition, if Figure 2 As shown in FIG. 1 , the node ND2 is supplied with a potential VD1, and then its potential changes according to the potential of the node ND1. Therefore, when rewriting the image data corresponding to the potential of the node ND2, i.e., the first image data, it is necessary to rewrite the image data corresponding to the potential of the node ND1, i.e., the second image data, to the pixel 10. On the other hand, when rewriting the second image data, as long as the charge supplied to the node ND2 is always maintained and does not leak from the transistor 12, etc., it is not necessary to rewrite the first image data. Therefore, in Figure 7 In the case shown, the brightness of the text can be adjusted by adjusting the potential supplied to the node ND1.

[0126] Here, as described above, when rewriting the first image data, the second image data needs to be rewritten to the pixel 10. On the other hand, when rewriting the second image data, the first image data does not need to be rewritten. Therefore, the image P1 is preferably an image with a lower rewriting frequency than the image P2.

[0127] <Configuration Example of Display Device>

[0128] Fig. 8A 1 is a block diagram of a configuration example of a display device 60 as a display device of one embodiment of the present invention. The display device 60 includes a display unit 61, a gate drive circuit 62, a data drive circuit 63, a current detection circuit 64, and a correction data generation circuit 65. In the display unit 61, pixels 10 are arranged in a matrix.

[0129] The gate drive circuit 62 extends in the row direction (horizontal direction) and is electrically connected to a plurality of wirings 31, 32, and 35 used as scan lines. As described above, the wirings 31, 32, and 35 are electrically connected to the pixel 10. The data drive circuit 63 extends in the column direction (vertical direction) and is electrically connected to a plurality of wirings 41, 42, and 45 used as data lines. The current detection circuit 64 is electrically connected to a plurality of wirings 54 extending in the column direction. As described above, the wirings 41, 42, 45, and 54 are electrically connected to the pixel 10.

[0130] The gate driving circuit 62 has a function of generating a signal for controlling the on and off of the transistors provided in the pixel 10, for example, a function of generating a signal for controlling the on and off of the transistors 11, 12, 14, and 15. The data driving circuit 63 has a function of generating threshold voltage correction data, first data, and second data.

[0131] Here, as described above, the data driving circuit 63 having high withstand voltage is not required. Therefore, an inexpensive display device 60 can be provided. In addition, the output potential of the data driving circuit can be suppressed from increasing, thereby reducing the power consumption of the display device 60.

[0132] The current detection circuit 64 has a function of detecting the current flowing through the wiring 54, generating data indicating the current value of the current, and supplying the generated data to the correction data generation circuit 65. The correction data generation circuit 65 has a function of generating threshold voltage correction data Dc based on the data supplied from the current detection circuit 64, and supplying the data to the data driving circuit 63. The data driving circuit 63 can set the potential of the wiring 45 to the potential corresponding to the supplied threshold voltage correction data Dc, that is, the potential Vc. In addition, the correction data generation circuit 65 can generate the threshold voltage correction data Dc based on not only the data indicating the current value of the current flowing through the wiring 54, but also the data of the gate-source potential difference (Vgs) and the gate-drain potential difference (Vds) of the transistor 13 when the current flows, for example.

[0133] Figure 8B is a block diagram showing a configuration example of the display device 60, and is also Fig. 8A A modified example of the display device 60 having the structure shown. Figure 8B The display device 60 of the structure shown in the figure includes a storage device 66 and a storage device 67. Fig. 8A The display device 60 shown has a different structure.

[0134] exist Figure 8B In the display device 60 of the structure shown, the threshold voltage correction data Dc of each pixel 10 generated by the correction data generation circuit 65 is written into the storage device 66. The threshold voltage correction data Dc written into the storage device 66 is read out at a predetermined timing and then supplied to the data driving circuit 63. The storage device 66 is preferably a volatile memory such as a DRAM or SRAM. Thus, the storage device 66 can be operated at a high speed, and thus the display device 60 can be operated at a high speed.

[0135] The threshold voltage correction data Dc written to the storage device 66 is also written to the storage device 67. The data retention time of the storage device 67 is longer than that of the storage device 66, and the threshold correction data Dc retained by the storage device 67 is supplied to the storage device 66 as needed. The storage device 67 is preferably a non-volatile memory such as a hard disk drive (HDD), a solid state drive (SSD), or a flash memory. By using a non-volatile memory as the storage device 67, for example, even when the power supply to the display device 60 stops and the data retained by the storage device 66 as a volatile memory disappears, data can be supplied from the storage device 67 to the storage device 66 to quickly restore the data. In addition, the threshold voltage correction data Dc is neither written directly from the correction data generation circuit 65 to the storage device 67 nor is the data retained by the storage device 67 directly supplied to the data driving circuit 63. Therefore, even if the operating speed of the storage device 67 is slow, the operating speed of the display device 60 will not be reduced.

[0136] As described above, the OS transistor is characterized in that the off-state current is extremely low. Therefore, by using the OS transistor to constitute the storage device 67, the storage device 67 can be formed as a non-volatile memory. In addition, by using the storage device 67 constituted by the OS transistor as a non-volatile memory, the structure of the storage device 67 can be made simpler than that of an HDD, an SSD, a flash memory, etc. Therefore, the manufacturing process of the storage device 67 can be simplified and an inexpensive display device 60 can be provided.

[0137] Thus, by making the display device 60 have Figure 8B The structure shown in FIG. 1 can hold the threshold voltage correction data Dc for a longer period than the period during which the threshold voltage correction data Dc is held in the pixel 10. Figure 2 In the illustrated period T01 , the frequency of the correction data generation circuit 65 generating the threshold voltage correction data Dc is reduced, so that the display device 60 can be operated at a high speed.

[0138] <Pixel Structure Example 2>

[0139] Fig. 9 is a diagram showing an example of the structure of the pixel 10, and is also Figure 1 A modified example of the structure of the pixel 10 is shown. Fig. 9 The pixel 10 of the structure shown in FIG. 1 is provided with a transistor 16. Figure 1 The structure of the pixel 10 shown is different.

[0140] In having Fig. 9 In the pixel 10 of the structure shown in FIG. 1 , the node ND3 is electrically connected to one of the source and drain of the transistor 13, one of the source and drain of the transistor 14, one of the source and drain of the transistor 16, the other electrode of the capacitor 22, and one electrode of the capacitor 23. The other of the source and drain of the transistor 16 is electrically connected to one electrode of the display element 20. The gate of the transistor 16 is electrically connected to the wiring 36. The wiring 36 is used as a scanning line and is connected to the display element 20. Fig. 8A and Figure 8B The gate drive circuit 62 is shown electrically connected.

[0141] The transistor 16 can be turned off during a period when the transistor 14 is turned on, and can be turned on during a period when the transistor 14 is turned off. That is, the signal supplied to the gate of the transistor 16 and the signal supplied to the gate of the transistor 14 can be complementary signals. For example, when the potential of the wiring 31 electrically connected to the gate of the transistor 14 is high, the potential of the wiring 36 electrically connected to the gate of the transistor 16 can be low, and when the potential of the wiring 31 is low, the potential of the wiring 36 can be high.

[0142] have Fig. 9 The pixel 10 with the structure shown can suppress the period other than the data readout period, for example Figure 2 Current flows through the display element 20 during the period T01, the period T11 to the period T13, and the period T21 shown in the above. Fig. 8A and Figure 8B The current detection circuit 64 shown accurately detects the current flowing through the wiring 54 via the transistor 13. In addition, abnormal display can be suppressed.

[0143] <Pixel Structure Example 3>

[0144] Fig. 10A and Fig. 10B An example of the structure of the pixel 10 is shown. Fig. 10A The pixel 10 shown has Figure 1 The transistors 11, 12, 14 and 15 of the pixel 10 shown have a back gate structure. Fig. 10B The pixel 10 shown has Fig. 9 The transistors 11, 12, and 14 to 16 of the pixel 10 shown in the figure have a back gate structure. The back gate is electrically connected to the front gate, which has the effect of increasing the on-state current of the transistor. In addition, the back gate can also be supplied with a different potential from the front gate. By adopting this structure, the threshold voltage of the transistor can be controlled. Although in Fig. 10A and Fig. 10B The structure in which all transistors have back gates is shown, but the pixel 10 may also include transistors without back gates.

[0145] <Pixel Structure Example 4>

[0146] Fig.11A is a diagram showing an example of the structure of the pixel 10, and is also Figure 1 A modified example of the structure of the pixel 10 is shown. Fig.11A The pixel 10 shown in the figure has a structure in which the other of the source and the drain of the transistor 15 is not electrically connected to the wiring 45 but is electrically connected to the wiring 41. Figure 1 The pixels 10 shown are different.

[0147] about Fig.11A The working method of the pixel 10 shown can be referred to Figures 2 to 6 Here, the potential of the wiring 41 is set to the potential V1 during the period T01, and the potential of the wiring 41 is set to the potential Vc during the period T11. In addition, the potential of the wiring 41 after the period T12 can be different from Figure 2 The potentials shown are the same.

[0148] also, Fig. 11B The pixel 10 shown has Fig.11AThe transistors 11, 12, 14 and 15 of the pixel 10 shown in the figure have a back gate structure. Fig. 11B , all transistors are shown to have a structure with back gates, but the pixel 10 may also include transistors without back gates.

[0149] <Example 2 of how pixels work>

[0150] Fig.12 It shows that Figure 1 A timing diagram of an example of an operating method of the pixel 10 of the structure shown is also Figure 2 A variation of the working method shown. Fig.12 The operation method shown in FIG. 1 corrects the threshold voltage of transistor 13 twice during period T11, which is different from Figure 2 The working method shown is different. Specifically, during period T11-1, the potential of wiring 45 is set to a potential calculated based on the current detected during period T01, that is, potential Vc1. As a result, the potential of node ND4 becomes potential Vc1. Then, the current flowing through wiring 54 through transistor 13 is detected again, and during period T11-2, the potential of wiring 45 is set to a potential calculated based on the detected current, that is, potential Vc2. As a result, the potential of node ND4 becomes potential Vc1. In addition, the threshold voltage can be corrected more than three times.

[0151] By performing the threshold voltage correction multiple times, the threshold voltage can be corrected with high accuracy, thereby enabling the display element 20 to display a high-quality image.

[0152] <Example 3 of how pixels work>

[0153] Fig.13 It shows that Figure 1 A timing diagram of an example of an operating method of the pixel 10 of the structure shown is also Figure 2 A variation of the working method shown. Fig.13 In the working method shown in the figure, the work shown in period T02 replaces the work shown in period T01 and period T11. Figure 2 The working methods shown are different.

[0154] During period T02, the potentials of wiring 31, wiring 32, and wiring 35 are set to high potentials, and then the potential of wiring 42 is set to potential V0, and the potential of wiring 45 is set to potential V1. As a result, transistors 11, 12, 14, and 15 are turned on, the potentials of node ND2 and node ND3 are set to potential V0, and the potential of node ND4 is set to potential V1. Through the above operation, current flows from wiring 53 through transistor 13 to wiring 54. This current is detected by a circuit provided outside pixel 10. In addition, Figure 2 Similarly to the case shown, the potential of the wiring 42 may not be equal to the potential of the wiring 54, that is, the potential V0. In addition, the potential of the wiring 41 may be any potential, but the potential is assumed to be 0V in the following description.

[0155] After the potential of the wiring 45 is set to the potential V1, the potential of the wiring 45 is lowered in a scanning manner. As a result, the potential of the node ND4 is also lowered, and the threshold voltage of the transistor 13 is increased, so that the current flowing through the wiring 54 through the transistor 13 is reduced. Then, when the current flowing through the wiring 54 through the transistor 13 becomes less than a certain value, the above scanning operation is stopped. The above is the operation of the period T02.

[0156] Here, when the potential of the wiring 45 is set to the potential Vc when the scanning operation is completed, the potential of the node ND4 becomes the potential Vc. Through the above operation, the potential of the back gate of the transistor 13 becomes the potential Vc, thereby correcting the threshold voltage of the transistor 13.

[0157] After the end of period T02, Figure 2 The same operation is performed after the period T12 shown. Fig.13 The working method shown.

[0158] like Fig.13 As shown, since the threshold voltage of the transistor 13 is corrected by the potential of the scanning wiring 45, it is not necessary to provide the correction data generation circuit 65, the storage device 66, and the storage device 67 in the display device 60. Thus, the display device 60 can be miniaturized and the area of ​​the display portion 61 can be increased.

[0159] This embodiment mode can be implemented in combination with the configurations described in other embodiment modes and the like as appropriate.

[0160] (Implementation Method 2)

[0161] In this embodiment, a configuration example of a display device which is one embodiment of the present invention is described with reference to the drawings.

[0162] exist Fig.14AIn the embodiment, a sealant 4005 is provided so as to surround a display portion 215 provided over a substrate 4001 , and the display portion 215 is sealed by the sealant 4005 and the substrate 4006 .

[0163] The display portion 215 includes the pixels described in Embodiment 1.

[0164] exist Fig.14A In the embodiment, the gate driving circuit 221, the data driving circuit 231, the data driving circuit 232, and the power supply circuit 241 all include a plurality of integrated circuits 4042 provided on a printed wiring board 4041. The integrated circuit 4042 is formed of a single crystal semiconductor or a polycrystalline semiconductor. The data driving circuit 231 and the data driving circuit 232 have the function of the data driving circuit described in Embodiment 1. The gate driving circuit 221 has the function of the gate driving circuit described in Embodiment 1. The power supply circuit 241 has the function of generating a predetermined potential supplied to the power supply line described in Embodiment 1.

[0165] Various signals and potentials are supplied to the gate driving circuit 221 , the power supply circuit 241 , the data driving circuit 231 , and the data driving circuit 232 via an FPC (Flexible printed circuit) 4018 .

[0166] The integrated circuit 4042 included in the gate driving circuit 221 and the power supply circuit 241 has a function of generating a selection signal supplied to the display portion 215. The integrated circuit 4042 included in the data driving circuit 231 and the data driving circuit 232 has a function of generating image data supplied to the display portion 215. The integrated circuit 4042 is mounted in a region different from a region surrounded by the sealant 4005 on the substrate 4001.

[0167] Note that there is no particular limitation on the connection method of the integrated circuit 4042, and a wire bonding method, a COG (Chip On Glass) method, a TCP (Tape Carrier Package) method, a COF (Chip On Film) method, or the like can be used.

[0168] Fig. 14B An example in which the integrated circuit 4042 included in the data driving circuit 231 and the data driving circuit 232 is mounted by a COG method is shown. In addition, by forming part or all of the driving circuit over a substrate having the display portion 215 formed thereon, a system-on-panel can be formed.

[0169] Fig. 14BAn example is shown in which the gate driver circuit 221 and the power supply circuit 241 are formed over a substrate on which the display portion 215 is formed. By forming the driver circuit and the pixel circuit in the display portion 215 at the same time, the number of components can be reduced, thereby improving productivity.

[0170] In addition, Fig. 14B In the embodiment, a sealant 4005 is provided so as to surround a display portion 215, a gate driver circuit 221, and a power supply circuit 241 provided over a substrate 4001. A substrate 4006 is provided over the display portion 215, the gate driver circuit 221, and the power supply circuit 241. Thus, the display portion 215, the gate driver circuit 221, and the power supply circuit 241 are sealed together with the display element by the substrate 4001, the sealant 4005, and the substrate 4006.

[0171] Although Fig. 14B An example is shown in which a data driving circuit 231 and a data driving circuit 232 are separately formed and installed on a substrate 4001, but one embodiment of the present invention is not limited to this structure, and a gate driving circuit may be separately formed and installed, or a part of the data driving circuit or a part of the gate driving circuit may be separately formed and installed.

[0172] In addition, a display device may include a panel in which a display element is sealed and a module in which an IC including a controller and the like is mounted on the panel.

[0173] The display unit and the gate driver circuit provided on the substrate include a plurality of transistors. As the transistors, for example, the following transistors can be applied.

[0174] The structures of the transistors included in the peripheral drive circuit and the transistors included in the pixel circuit of the display unit may have the same structure or different structures. The transistors included in the peripheral drive circuit may all have the same structure or may combine two or more structures. Similarly, the transistors included in the pixel circuit may all have the same structure or may combine two or more structures.

[0175] In addition, an input device can be provided over the substrate 4006 . Fig.14A and Fig. 14B The structure in which the input device is provided to the display device as shown can be used as a touch panel. Fig.14A and Fig. 14B The input device is not shown in the figure. The structure of the input device will be described later.

[0176] The sensing element (also referred to as a sensor element) included in the touch panel of one embodiment of the present invention is not particularly limited. Various sensors capable of detecting the approach or contact of a detection object such as a finger or a stylus pen can be used as the detection element.

[0177] For example, various types of sensors such as electrostatic capacitance, resistance film, surface acoustic wave, infrared, optical, and pressure-sensitive can be used.

[0178] In this embodiment, a touch panel including a capacitive sensing element is taken as an example for description.

[0179] As the electrostatic capacitance type, there are surface type electrostatic capacitance type, projected type electrostatic capacitance type, etc. In addition, as the projected type electrostatic capacitance type, there are self capacitance type, mutual capacitance type, etc. It is preferable to use the mutual capacitance type because multi-point sensing can be performed simultaneously.

[0180] The touch panel of one embodiment of the present invention can have various structures such as a structure in which a display device and a detection element manufactured separately are bonded together, a structure in which electrodes constituting the detection element are provided on one or both of a substrate supporting the display element and a counter substrate.

[0181] Fig.15A and Fig. 15B An example of a touch panel is shown. Fig.15A is a perspective view of touch panel 4210. Fig. 15B 42 is a perspective schematic diagram of input device 4200. Note that for clarity, only typical components are shown.

[0182] The touch panel 4210 has a structure in which a display device and a sensing element which are manufactured separately are bonded together.

[0183] The touch panel 4210 includes an input device 4200 and a display device which are overlapped.

[0184] The input device 4200 includes a substrate 4263, an electrode 4227, an electrode 4228, a plurality of wirings 4237, a plurality of wirings 4238, and a plurality of wirings 4239. For example, the electrode 4227 may be electrically connected to the wiring 4237 or the wiring 4239. In addition, the electrode 4228 may be electrically connected to the wiring 4238. The FPC 4272 may be electrically connected to the plurality of wirings 4237, the plurality of wirings 4238, and the plurality of wirings 4239, respectively. The FPC 4272 may be provided with an IC 4273.

[0185] The display device may include a touch sensor between the substrate 4001 and the substrate 4006. When the touch sensor is provided between the substrate 4001 and the substrate 4006, an optical touch sensor using a photoelectric conversion element may be used in addition to an electrostatic capacitive touch sensor.

[0186] <Example 1 of Cross-sectional Structure of Display Device>

[0187] Fig.16A It is along Fig. 14B0 is a cross-sectional view taken along the dot-dash line N1-N2 in FIG. 1 , and shows a structural example of a light-emitting display device adopting a top emission structure using a color filter. Fig.16A The display device shown includes an electrode 4015, which is electrically connected to a terminal of an FPC 4018 via an anisotropic conductive layer 4019. Fig.16A In the embodiment, the electrode 4015 is electrically connected to the wiring 4014 in an opening formed in the insulating layer 4112 , the insulating layer 4111 , and the insulating layer 4110 .

[0188] The electrode 4015 and the electrode layer 4030 are formed using the same conductive layer, and the wiring 4014 and the source electrode and the drain electrode of the transistor 4010 and the transistor 4011 are formed using the same conductive layer.

[0189] In addition, the display portion 215 and the gate driver circuit 221 provided over the substrate 4001 include a plurality of transistors. Fig.16A , a transistor 4010 in the display portion 215 and a transistor 4011 in the gate driver circuit 221 are shown. Fig.16A Although bottom-gate transistors are shown as the transistor 4010 and the transistor 4011 , top-gate transistors may also be used.

[0190] exist Fig.16A In the embodiment of the present invention, an insulating layer 4112 is provided over the transistor 4010 and the transistor 4011. In addition, a partition wall 4510 is formed over the insulating layer 4112.

[0191] In addition, the transistor 4010 and the transistor 4011 are provided over the insulating layer 4102. In addition, the transistor 4010 and the transistor 4011 include an electrode 4017 formed over the insulating layer 4111. The electrode 4017 can function as a back gate electrode.

[0192] also, Fig.16A The display device shown includes a capacitor 4020. The capacitor 4020 includes an electrode 4021 formed in the same process as a gate electrode of the transistor 4010 and electrodes formed in the same process as a source electrode and a drain electrode of the transistor 4010. The electrodes overlap with each other with the insulating layer 4103 interposed therebetween.

[0193] Generally, the capacitance of a capacitor provided in a pixel portion of a display device is set so as to hold charge for a predetermined period in consideration of leakage current of a transistor provided in the pixel portion, etc. The capacitance of the capacitor may be set in consideration of the off-state current of the transistor, etc.

[0194] The transistor 4010 provided in the display portion 215 is electrically connected to the display element.

[0195] also, Fig.16AThe display device shown uses insulating layers through which impurity elements are less likely to pass as the insulating layer 4111 and the insulating layer 4103. When the semiconductor layer of the transistor is sandwiched between the insulating layer 4111 and the insulating layer 4103, mixing of impurities from the outside can be prevented.

[0196] As a display element included in the display device, a light-emitting element using electroluminescence (also referred to as an EL element) can be applied. The EL element has a layer (also referred to as an EL layer) containing a light-emitting compound between a pair of electrodes. When a potential difference higher than the threshold voltage of the EL element is generated between the pair of electrodes, holes are injected into the EL layer from the anode side, and electrons are injected into the EL layer from the cathode side. The injected electrons and holes recombine in the EL layer, whereby the light-emitting substance contained in the EL layer emits light.

[0197] EL elements are distinguished depending on whether the light-emitting material is an organic compound or an inorganic compound. Generally, the former is called an organic EL element, and the latter is called an inorganic EL element.

[0198] In an organic EL element, electrons are injected into the EL layer from one electrode and holes are injected into the EL layer from the other electrode by applying voltage. The light-emitting organic compound forms an excited state by the recombination of these carriers (electrons and holes), and emits light when returning from the excited state to the ground state. Due to this mechanism, this light-emitting element is called a current-excitation light-emitting element.

[0199] In addition to the light-emitting compound, the EL layer may also include substances with high hole injection properties, substances with high hole transport properties, hole blocking materials, substances with high electron transport properties, substances with high electron injection properties, or bipolar substances (substances with high electron transport properties and hole transport properties).

[0200] The EL layer can be formed by a method such as an evaporation method (including a vacuum evaporation method), a transfer method, a printing method, an inkjet method, or a coating method.

[0201] Inorganic EL elements are classified into dispersed inorganic EL elements and thin-film inorganic EL elements according to their element structures. Dispersed inorganic EL elements include a light-emitting layer in which particles of a light-emitting material are dispersed in a binder, and its light-emitting mechanism is donor-acceptor recombination type light-emitting using donor energy level and acceptor energy level. Thin-film inorganic EL elements are structures in which a light-emitting layer is sandwiched between dielectric layers, and the dielectric layers sandwiching the light-emitting layer are sandwiched between electrodes, and its light-emitting mechanism is localized light-emitting using inner shell electron transitions of metal ions. Note that an organic EL element is used as a light-emitting element for explanation here.

[0202] In order to extract the light, at least one of the pair of electrodes of the light-emitting element is made transparent. A transistor and a light-emitting element are formed on a substrate. As the light-emitting element, a top emission structure that extracts light from the surface opposite to the substrate; a bottom emission structure that extracts light from the surface on one side of the substrate; and a double-sided emission structure that extracts light from both surfaces can be used.

[0203] Fig.16A This is an example of a light-emitting display device (also referred to as an "EL display device") using a light-emitting element as a display element. The light-emitting element 4513 used as a display element is electrically connected to the transistor 4010 provided in the display portion 215. The light-emitting element 4513 can be an element that emits white light. Although the light-emitting element 4513 has a stacked structure of an electrode layer 4030, a light-emitting layer 4511, and an electrode layer 4031, it is not limited to this structure. The structure of the light-emitting element 4513 can be appropriately changed according to the direction of extracting light from the light-emitting element 4513, etc.

[0204] The partition wall 4510 is formed using an organic insulating material or an inorganic insulating material. In particular, it is preferable to use a photosensitive resin material, and the partition wall 4510 is formed in the electrode layer 4030 so as to include an opening whose side surface is an inclined surface having a continuous curvature.

[0205] The light-emitting layer 4511 may be formed of a single layer or a stack of a plurality of layers.

[0206] The light-emitting layer 4511 may contain an inorganic compound such as quantum dots. For example, by using quantum dots (QD) in the light-emitting layer, they can also be used as a light-emitting material.

[0207] Quantum dots are semiconductor nanocrystals with a size of several nanometers to tens of nanometers and consist of 1×10 3 to 1×10 6 The energy transfer of quantum dots depends on their size, so even quantum dots made of the same substance have different emission wavelengths depending on their size. Therefore, by changing the size of the quantum dots used, it is easy to change the emission wavelength.

[0208] In addition, the peak width of the emission spectrum of quantum dots is narrow, so luminescence with high color purity can be obtained. Furthermore, the theoretical internal quantum efficiency of quantum dots is considered to be approximately 100%, that is, it greatly exceeds 25% of organic compounds that exhibit fluorescent luminescence and is equal to organic compounds that exhibit phosphorescent luminescence. Therefore, by using quantum dots as luminescent materials, a light-emitting element with high luminescence efficiency can be obtained. Moreover, quantum dots as inorganic materials are also excellent in substantial stability, so a light-emitting element with a long service life can be obtained.

[0209] Materials constituting quantum dots include Group 14 elements, Group 15 elements, Group 16 elements, compounds containing multiple Group 14 elements, compounds of Group 4 to Group 14 elements and Group 16 elements, compounds of Group 2 elements and Group 16 elements, compounds of Group 13 elements and Group 15 elements, compounds of Group 13 elements and Group 17 elements, compounds of Group 14 elements and Group 15 elements, compounds of Group 11 elements and Group 17 elements, iron oxides, titanium oxides, chalcogenides, various semiconductor clusters, and the like.

[0210] Specifically, cadmium selenide, cadmium sulfide, cadmium telluride, zinc selenide, zinc oxide, zinc sulfide, zinc telluride, mercury sulfide, mercury selenide, mercury telluride, indium arsenide, indium phosphide, gallium arsenide, gallium phosphide, indium nitride, gallium nitride, indium antimonide, gallium antimonide, aluminum phosphide, aluminum arsenide, aluminum antimonide, lead selenide, lead telluride, lead sulfide, indium selenide, indium telluride, indium sulfide, gallium selenide, arsenic sulfide, arsenic selenide, arsenic telluride, antimony sulfide, antimony selenide, antimony telluride, bismuth sulfide, bismuth selenide, bismuth telluride, silicon, silicon carbide, germanium, tin, selenium, tellurium, boron, carbon, phosphorus, boron nitride, boron phosphide, boron arsenide, aluminum nitride, aluminum sulfide, barium sulfide, barium selenide, barium telluride, calcium sulfide, calcium selenide, calcium telluride , beryllium sulfide, beryllium selenide, beryllium telluride, magnesium sulfide, magnesium selenide, germanium sulfide, germanium selenide, germanium telluride, tin sulfide, tin sulfide, tin selenide, tin telluride, lead oxide, copper fluoride, copper chloride, copper bromide, copper iodide, copper oxide, copper selenide, nickel oxide, cobalt oxide, cobalt sulfide, iron oxide, iron sulfide, manganese oxide, molybdenum sulfide, vanadium oxide, tungsten oxide, tantalum oxide, titanium oxide, zirconium oxide, silicon nitride, germanium nitride, aluminum oxide, barium titanate, selenium zinc cadmium compound, indium arsenic phosphorus compound, cadmium selenium sulfur compound, cadmium selenium tellurium compound, indium gallium arsenic compound, indium gallium selenide compound, indium selenium sulfur compound, copper indium sulfur compound and their combination, etc., but not limited to this. In addition, so-called alloy-type quantum dots with arbitrary proportions can also be used. For example, cadmium-selenium-sulfur alloy quantum dots are one of the effective methods for obtaining blue light because the emission wavelength can be changed by changing the content ratio of the elements.

[0211] As the structure of quantum dot, there are core type, core shell (Core Shell) type, core multi-shell (Core Multishell) type etc.. Any of the above can be used, but by using other inorganic materials covering the core and having a wider band gap to form a shell, the influence of defects or dangling bonds present on the surface of the nanocrystal can be reduced, thereby significantly improving the quantum efficiency of luminescence. Thus, preferably use a core shell type or core multi-shell type quantum dot. As an example of the material of the shell, zinc sulfide or zinc oxide can be cited.

[0212] In addition, in quantum dots, since the proportion of surface atoms is high, the reactivity is high and aggregation occurs easily. Therefore, the surface of the quantum dots is preferably attached with a protective agent or provided with a protective group. This can prevent aggregation and improve the solubility in solvents. In addition, the electrical stability can be improved by reducing the reactivity. Examples of protective agents (or protective groups) include: polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene ole ... ether) and other polyoxyethylene alkyl ethers; tripropyl phosphine, tributyl phosphine, trihexyl phosphine, trioctyl phosphine and other trialkyl phosphines; polyoxyethylene n-octyl phenyl ether, polyoxyethylene n-nonyl phenyl ether and other polyoxyethylene alkyl phenyl ethers; tertiary amines such as tri(n-hexyl)amine, tri(n-octyl)amine, tri(n-decyl)amine; organic phosphorus compounds such as tripropyl phosphine oxide, tributyl phosphine oxide, trihexyl phosphine oxide, trioctyl phosphine oxide, tridecyl phosphine oxide; polyethylene glycol diesters such as polyethylene glycol dilaurate and polyethylene glycol distearate; Organic nitrogen compounds such as pyridine, lutiidine, collidine, quinoline and other nitrogen-containing aromatic compounds; aminoalkanes such as hexylamine, octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine and other aminoalkanes; dialkyl sulfides such as dibutyl sulfide; dialkyl sulfoxides such as dimethyl sulfoxide and dibutyl sulfoxide; organic sulfur compounds such as sulfur-containing aromatic compounds such as thiophene; higher fatty acids such as palmitic acid, stearic acid, oleic acid; ethanol; sorbitan fatty acid esters; fatty acid-modified polyesters; tertiary amine-modified polyurethanes; polyethyleneimines, etc.

[0213] The smaller the size of the quantum dot, the larger the band gap, so the size is appropriately adjusted to obtain the desired wavelength of light. As the crystal size becomes smaller, the luminescence of the quantum dot migrates to the blue side (i.e., to the high energy side), so by changing the size of the quantum dot, the luminescence wavelength can be adjusted in the wavelength region of the spectrum covering the ultraviolet region, the visible light region, and the infrared region. The size (diameter) of the commonly used quantum dots is greater than 0.5nm and less than 20nm, preferably greater than 1nm and less than 10nm. In addition, the smaller the size distribution of the quantum dot, the narrower the emission spectrum, so luminescence with high color purity can be obtained. In addition, there is no particular restriction on the shape of the quantum dot, which can be spherical, rod-shaped, disc-shaped, or other shapes. In addition, the quantum rod as a rod-shaped quantum dot has the function of presenting directional light, so by using the quantum rod as a luminescent material, a light-emitting element with higher external quantum efficiency can be obtained.

[0214] In organic EL elements, the concentration quenching of the luminescent material is usually suppressed by dispersing the luminescent material in the host material, thereby improving the luminous efficiency. The host material needs to have a singlet excitation energy level or a triplet excitation energy level higher than the luminescent material. In particular, when a blue phosphorescent material is used as a luminescent material, a host material with a triplet excitation energy level higher than the blue phosphorescent material and a long life is required, and the development of such a material is extremely difficult. Here, quantum dots can ensure luminous efficiency even when only quantum dots are used to form a luminescent layer without using a host material, so a luminescent element with a long life can be obtained. When only quantum dots are used to form a luminescent layer, the quantum dots preferably have a core-shell structure (including a core-multi-shell structure).

[0215] When quantum dots are used as the light-emitting material of the light-emitting layer, the thickness of the light-emitting layer is greater than 3 nm and less than 100 nm, preferably greater than 10 nm and less than 100 nm, and the ratio of quantum dots contained in the light-emitting layer is greater than 1 vol.% and less than 100 vol.%. Note that it is preferred that the light-emitting layer is formed only by quantum dots. In addition, when forming a light-emitting layer in which the quantum dots are used as a light-emitting material and dispersed in a host material, the quantum dots can be dispersed in the host material or the host material and the quantum dots can be dissolved or dispersed in a suitable liquid medium and formed using a wet method (spin coating, casting, dispensing coating, blade coating, roller coating, inkjet, printing, spraying, curtain coating, Langmuir-Blodgett method, etc.). In addition to the above-mentioned wet method, a light-emitting layer using a phosphorescent light-emitting material can also be formed by vacuum evaporation.

[0216] As the liquid medium used for the wet method, for example, ketones such as methyl ethyl ketone and cyclohexanone; fatty acid esters such as ethyl acetate; halogenated hydrocarbons such as dichlorobenzene; aromatic hydrocarbons such as toluene, xylene, mesitylene, cyclohexylbenzene; aliphatic hydrocarbons such as cyclohexane, decalin, dodecane; organic solvents such as dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).

[0217] In order to prevent oxygen, hydrogen, moisture, carbon dioxide, etc. from invading the light-emitting element 4513, a protective layer may be formed on the electrode layer 4031. As the protective layer, silicon nitride, silicon nitride oxide, aluminum oxide, aluminum nitride, aluminum oxynitride, aluminum nitride oxide, DLC (Diamond Like Carbon), etc. can be used. In addition, a filler 4514 is provided and sealed in the space sealed by the substrate 4001, the substrate 4006, and the sealant 4005. In this way, in order not to be exposed to the outside air, it is preferable to use a protective film (adhesive film, ultraviolet curing resin film, etc.) with high airtightness and little degassing, and a covering material for packaging (encapsulation).

[0218] As filler 4514, in addition to inert gases such as nitrogen or argon, ultraviolet curing resin or thermosetting resin may be used, for example, PVC (polyvinyl chloride), acrylic resin, polyimide, epoxy resin, silicone resin, PVB (polyvinyl butyral) or EVA (ethylene vinyl acetate), etc. Filler 4514 may also contain a desiccant.

[0219] As the sealant 4005, a glass material such as glass frit, a curable resin such as a two-liquid mixed resin that cures at room temperature, a light-curable resin, a thermosetting resin, or other resin material can be used. The sealant 4005 may contain a desiccant.

[0220] also, Fig.16A The display device shown includes a coloring layer 4301 and a light-shielding layer 4302. The coloring layer 4301 includes a region overlapping with the light-emitting element 4513 via a filler 4514, and the light-shielding layer 4302 includes a region overlapping with the partition 4510 via the filler 4514.

[0221] The coloring layer 4301 is a colored layer that transmits light in a specific wavelength region. For example, a color filter that transmits red, green, blue, cyan, magenta, or yellow light can be used. Materials that can be used for the coloring layer 4301 include metal materials, resin materials, pigments, or resin materials containing dyes.

[0222] The coloring layer 4301 is provided between adjacent light-shielding layers 4302. The light-shielding layer 4302 has a function of shielding light emitted from the light-emitting element 4513 and suppressing color mixing between adjacent light-emitting elements 4513. Here, by providing the coloring layer 4301 in such a manner that the end of the coloring layer 4301 overlaps with the light-shielding layer 4302, light leakage can be suppressed. As the light-shielding layer 4302, a material that shields light emitted from the light-emitting element 4513 can be used, for example, a black matrix can be formed using a metal material or a resin material containing a pigment or a dye.

[0223] In addition, as required, a polarizing plate or circular polarizing plate (including elliptical polarizing plate) or a phase difference plate (λ / 4 plate, λ / 2 plate) may be appropriately provided on the light emitting surface of the light emitting element. In addition, an anti-reflection film may be provided on the polarizing plate or circular polarizing plate. For example, an anti-glare treatment may be performed, which is a treatment for reducing reflected glare by utilizing the surface concavity and convexity to diffuse reflected light.

[0224] By providing a light-emitting element with a microcavity structure, light with high color purity can be extracted.

[0225] Regarding the electrode layer 4030 and the electrode layer 4031, their transmittance and reflectivity may be selected according to the direction of light extraction, the location where the electrode layer is provided, and the pattern structure of the electrode layer.

[0226] As the electrode layer 4030 and the electrode layer 4031, a light-transmitting conductive material such as indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide, indium tin oxide containing titanium oxide, indium zinc oxide, or indium tin oxide added with silicon oxide can be used.

[0227] In addition, electrode layer 4030 and electrode layer 4031 can be formed using one or more of metals such as tungsten (W), molybdenum (Mo), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), cobalt (Co), nickel (Ni), titanium (Ti), platinum (Pt), aluminum (Al), copper (Cu), silver (Ag), their alloys, and their metal nitrides.

[0228] In addition, the electrode layer 4030 and the electrode layer 4031 can be formed using a conductive composition containing a conductive polymer (also called a conductive polymer). As the conductive polymer, a so-called π-electron conjugated conductive polymer can be used. For example, polyaniline or its derivatives, polypyrrole or its derivatives, polythiophene or its derivatives, or a copolymer composed of two or more of aniline, pyrrole and thiophene or its derivatives can be cited.

[0229] Furthermore, since transistors are easily damaged by static electricity or the like, it is preferable to provide a protection circuit for protecting the drive circuit. The protection circuit is preferably formed using a nonlinear element.

[0230] like Fig.16A As shown, by adopting a color filter method in which a light-emitting element 4513 that emits white light is combined with a coloring layer, productivity of a display device of one embodiment of the present invention can be improved.

[0231] Fig. 16B is Fig. 14B The cross-sectional view of the portion indicated by the dot-dash line N1-N2 in FIG. Fig.16A The display devices shown differ in that Fig. 16B The display device does not include a color filter and adopts a separate coating method. In the display device of the separate coating method, the light emitting element 4513 can emit light in white, red, green, blue, cyan, magenta, yellow, or the like depending on the material constituting the light emitting layer 4511.

[0232] By adopting Fig. 16B The separate coating method shown can extract light with high color purity. In addition, by providing a color filter, even a display device using the separate coating method can extract light with higher color purity.

[0233] Furthermore, the display device according to one embodiment of the present invention may adopt a color conversion method or a quantum dot method, etc.

[0234] <Example 2 of the cross-sectional structure of a display device>

[0235] Fig.17 It is along Fig. 14B The cross-sectional view along the dot-dash line N1-N2 in FIG. 1 shows a structural example of a display device using a light-emitting element, namely, an LED, particularly a Micro LED, as a display element. Fig.17 etc., without explanation Fig.16A The display device has the same structure as shown in the above.

[0236] In having Fig.17 In the display device having the structure shown, the electrode layer 4031 is provided in the same layer as the electrode layer 4030. In addition, the display element 782 is provided on the insulating layer 4112. The display element 782 is electrically connected to the electrode layer 4030 through the bump 791, and is electrically connected to the electrode layer 4031 through the bump 793.

[0237] In addition, a light-shielding layer 795 is provided in a space sealed by the substrate 4001, the substrate 4006, and the sealant 4005. The light-shielding layer 795 is preferably provided between adjacent display elements 782. By providing the light-shielding layer 795 between adjacent display elements 782, light leakage to adjacent pixels and color mixing between pixels can be suppressed. As the light-shielding layer 795, a resin containing a pigment, a dye, or carbon black can be used. In addition, the side surface of the display element 782 is preferably in contact with the light-shielding layer 795. By covering the side surface of the display element 782 with the light-shielding layer 795, light leakage to adjacent pixels and color mixing between pixels can be suppressed. Note that Fig.17 The structure in which the height of the top surface of the light shielding layer 795 is substantially the same as the height of the top surface of the display element 782 is shown, but one embodiment of the present invention is not limited to this. The height of the top surface of the light shielding layer 795 may be lower or higher than the height of the top surface of the display element 782. By making the height of the top surface of the light shielding layer 795 substantially equal to or higher than the height of the top surface of the display element 782, light leakage to adjacent pixels and color mixing between pixels can be effectively suppressed.

[0238] The display element 782 includes a semiconductor layer 781 on a substrate 771. The semiconductor layer 781 includes an n-type semiconductor layer 775, a light-emitting layer 777 on the n-type semiconductor layer 775, and a p-type semiconductor layer 779 on the light-emitting layer 777. As a material for the p-type semiconductor layer 779, a material having a band gap energy greater than that of the light-emitting layer 777 and capable of confining carriers in the light-emitting layer 777 can be used.

[0239] The display element 782 further includes an electrode layer 785 serving as a cathode on the n-type semiconductor layer 775, an electrode layer 783 serving as a contact electrode on the p-type semiconductor layer 779, and an electrode layer 787 serving as an anode on the electrode layer 783. The top surface and side surfaces of the electrode layer 783 are preferably covered with an insulating layer 789. The insulating layer 789 serves as a protective film for the display element 782.

[0240] In addition, the n-type semiconductor layer 775 and the p-type semiconductor layer 779 may be a p-type semiconductor layer and an n-type semiconductor layer, respectively. In this case, the electrode layer 785 and the electrode layer 787 may be used as an anode and a cathode, respectively.

[0241] By providing a bump 791 between the electrode layer 785 and the electrode layer 4030, the electrode layer 785 is electrically connected to the electrode layer 4030. In addition, by providing a bump 793 between the electrode layer 787 and the electrode layer 4031, the electrode layer 787 is electrically connected to the electrode layer 4031. Fig.17 In the embodiment, the height of the position where the electrode layer 785 is set is different from the height of the position where the electrode layer 787 is set, and the height of the bump 791 is also different from the height of the bump 793. When the height of the position where the electrode layer 785 is set is equal to the height of the position where the electrode layer 787 is set, the height of the bump 791 and the height of the bump 793 can be approximately equal.

[0242] The display element 782 may be an LED. In this case, the area of ​​the region emitting light is 1 mm 2 Below, preferably 10000 μm 2 Below, more preferably 3000 μm 2 Below, more preferably 700 μm 2 The following. By reducing the area of ​​the region where light is emitted, the power consumption of the display device of one embodiment of the present invention can be reduced. In addition, the display device of one embodiment of the present invention can be made thinner and lighter. Furthermore, the contrast of the display device of one embodiment of the present invention can be increased to increase the viewing angle, thereby displaying a high-quality image.

[0243] Fig.18 yes Fig.17 In a modified example of a display device having a structure shown in FIG. 4 , a coloring layer 4301, a light shielding layer 4302, and a fluorescent layer 797 are provided between the substrate 4006, the display element 782, and the light shielding layer 795. Fig.17 The display devices shown have different structures.

[0244] The coloring layer 4301 has a region overlapping with the display element 782. The light-shielding layer 4302 is provided so that an end portion thereof overlaps with an end portion of the coloring layer 4301. Furthermore, the fluorescent layer 797 is provided over the coloring layer 4301.

[0245] Therefore, the fluorescent layer 797, the display element 782, and the coloring layer 4301 have overlapping areas. Fig.18 As shown, the end of the fluorescent layer 797 is preferably located outside the end of the display element 782, and the end of the colored layer 4301 is preferably located outside the end of the fluorescent layer 797. By adopting this structure, light leakage to adjacent pixels and color mixing between pixels can be suppressed.

[0246] The filler 4514 is provided between the coloring layer 4301 , the light-shielding layer 4302 , and the fluorescent layer 797 , and the display element 782 and the light-shielding layer 795 .

[0247] For example, by adopting a structure in which the fluorescent layer 797 includes a fluorescent body that emits yellow light and the light-emitting element 782 emits blue light, white light is emitted from the fluorescent layer 797. Here, when the coloring layer 4301 is a coloring layer that transmits red light, the light emitted by the display element 782 passes through the fluorescent layer 797 and the coloring layer 736 and is emitted as red light to the display surface side. Similarly, when the coloring layer 4301 is a coloring layer that transmits green light, the light emitted by the display element 782 passes through the fluorescent layer 797 and the coloring layer 736 and is emitted as green light to the display surface side. In addition, when the coloring layer 4301 is a coloring layer that transmits blue light, the light emitted by the display element 782 passes through the fluorescent layer 797 and the coloring layer 736 and is emitted as blue light to the display surface side. Thus, a single display element 782 can be used for color display. In addition, since the type of the display element 782 used for the display device is one type, a display device of one embodiment of the present invention can be manufactured using a simple method. The price of a display device of one embodiment of the present invention can also be low.

[0248] For example, a structure may be adopted in which the phosphor layer 797 includes a phosphor that emits red light and the light-emitting element 782 emits blue-green light, so that white light is emitted from the phosphor layer 797. In addition, a structure may be adopted in which the phosphor layer 797 includes a phosphor that emits red light, a phosphor that emits green light, and a phosphor that emits blue light and the light-emitting element 782 emits near-ultraviolet light or violet light, so that white light is emitted from the phosphor layer 797.

[0249] This embodiment mode can be implemented in combination with the configurations described in other embodiment modes and the like as appropriate.

[0250] (Implementation 3)

[0251] In this embodiment, examples of transistors that can be used instead of the transistors described in the above embodiment will be described with reference to the drawings.

[0252] The display device of one embodiment of the present invention can be manufactured using various types of transistors such as bottom-gate transistors and top-gate transistors. Therefore, the material of the semiconductor layer or the transistor structure used can be easily replaced according to the existing production line.

[0253] 〔Bottom-gate transistor〕

[0254] Fig.19A1 8 is a cross-sectional view of a channel protection transistor 810 which is a type of bottom-gate transistor. Fig.19A1 In the embodiment, the transistor 810 is formed on a substrate 771. In addition, the transistor 810 includes an electrode 746 on the substrate 771 via an insulating layer 772. In addition, a semiconductor layer 742 is included on the electrode 746 via an insulating layer 726. The electrode 746 may be used as a gate electrode. The insulating layer 726 may be used as a gate insulating layer.

[0255] In addition, an insulating layer 741 is included on the channel formation region of the semiconductor layer 742. In addition, an electrode 744a and an electrode 744b are included on the insulating layer 726 in a manner of contacting a portion of the semiconductor layer 742. The electrode 744a can be used as one of the source electrode and the drain electrode. The electrode 744b is used as the other of the source electrode and the drain electrode. A portion of the electrode 744a and a portion of the electrode 744b are formed on the insulating layer 741.

[0256] The insulating layer 741 is used as a channel protection layer. By providing the insulating layer 741 on the channel formation region, the semiconductor layer 742 can be prevented from being exposed when the electrode 744a and the electrode 744b are formed. Thus, the channel formation region of the semiconductor layer 742 can be prevented from being etched when the electrode 744a and the electrode 744b are formed. According to one embodiment of the present invention, a transistor with good electrical characteristics can be realized.

[0257] In addition, the transistor 810 includes an insulating layer 728 over the electrode 744 a , the electrode 744 b , and the insulating layer 741 , and includes an insulating layer 729 over the insulating layer 728 .

[0258] When an oxide semiconductor is used for the semiconductor layer 742, it is preferable to use a material that can remove oxygen from a portion of the semiconductor layer 742 to generate oxygen vacancies for at least the portion of the electrode 744a and the electrode 744b that is in contact with the semiconductor layer 742. The carrier concentration in the region where the oxygen vacancies are generated in the semiconductor layer 742 increases, and the region is converted to n-type and becomes an n-type region (n + When an oxide semiconductor is used for the semiconductor layer 742, an example of a material that can remove oxygen from the semiconductor layer 742 to generate oxygen vacancies may include tungsten, titanium, and the like.

[0259] By forming the source region and the drain region in the semiconductor layer 742, the contact resistance between the electrode 744a and the electrode 744b and the semiconductor layer 742 can be reduced. Therefore, the electrical characteristics of the transistor such as field effect mobility and threshold voltage can be improved.

[0260] When a semiconductor such as silicon is used for the semiconductor layer 742, a layer used as an n-type semiconductor or a p-type semiconductor is preferably provided between the semiconductor layer 742 and the electrode 744a and between the semiconductor layer 742 and the electrode 744b. The layer used as an n-type semiconductor or a p-type semiconductor can be used as a source region or a drain region of a transistor.

[0261] The insulating layer 729 is preferably formed using a material having a function of preventing impurities from diffusing from the outside into the transistor or suppressing diffusion of impurities. Alternatively, the insulating layer 729 may be omitted as necessary.

[0262] Fig.19A2 The transistor 811 shown is different from the transistor 810 in that the transistor 811 includes an electrode 723 which can function as a back gate electrode over the insulating layer 729. The electrode 723 can be formed using the same material and method as the electrode 746.

[0263] Generally speaking, the back gate electrode is formed using a conductive layer and is arranged in a manner that the channel formation region of the semiconductor layer is sandwiched by the gate electrode and the back gate electrode. Therefore, the back gate electrode can have the same function as the gate electrode. The potential of the back gate electrode can be equal to that of the gate electrode, or it can be a ground potential (GND potential) or an arbitrary potential. In addition, by independently changing the potential of the back gate electrode without being linked to the gate electrode, the threshold voltage of the transistor can be changed.

[0264] The electrode 746 and the electrode 723 can both be used as gate electrodes. Therefore, the insulating layer 726, the insulating layer 741, the insulating layer 728, and the insulating layer 729 can all be used as gate insulating layers. Alternatively, the electrode 723 may be provided between the insulating layer 728 and the insulating layer 729.

[0265] Note that when one of the electrode 746 and the electrode 723 is referred to as a "gate electrode", the other is referred to as a "back gate electrode". For example, in the transistor 811, when the electrode 723 is referred to as a "gate electrode", the electrode 746 is referred to as a "back gate electrode". In addition, when the electrode 723 is used as a "gate electrode", the transistor 811 can be said to be a top gate transistor. In addition, one of the electrode 746 and the electrode 723 is sometimes referred to as a "first gate electrode", and the other is sometimes referred to as a "second gate electrode".

[0266] By providing the electrode 746 and the electrode 723 across the semiconductor layer 742 and setting the potential of the electrode 746 and the electrode 723 to be the same, the region through which the carriers flow in the semiconductor layer 742 is further expanded in the thickness direction, so the amount of carrier movement increases. As a result, the on-state current of the transistor 811 increases, and the field effect mobility also increases.

[0267] Therefore, the transistor 811 has a large on-state current relative to the occupied area. That is, the occupied area of ​​the transistor 811 can be reduced relative to the required on-state current. According to one embodiment of the present invention, the occupied area of ​​the transistor can be reduced.

[0268] In addition, since the gate electrode and the back gate electrode are formed using a conductive layer, they have a function of preventing the electric field generated outside the transistor from affecting the semiconductor layer forming the channel (especially the electric field shielding function against static electricity, etc.). In addition, when the back gate electrode is formed larger than the semiconductor layer so as to cover the semiconductor layer with the back gate electrode, the electric field shielding function can be improved.

[0269] Furthermore, by forming the back gate electrode using a light-shielding conductive film, light can be prevented from entering the semiconductor layer from the back gate electrode side, thereby preventing light degradation of the semiconductor layer and preventing degradation of electrical characteristics such as threshold voltage drift of the transistor.

[0270] According to one embodiment of the present invention, a highly reliable transistor can be realized. In addition, a highly reliable display device and the like can be realized.

[0271] Figure 19B1 A cross-sectional view of a channel protection transistor 820, which is one of the bottom-gate transistors, is shown. The transistor 820 has a structure substantially the same as the transistor 810, except that the insulating layer 741 covers the end of the semiconductor layer 742. In addition, in the opening formed by selectively removing the portion of the insulating layer 741 overlapping the semiconductor layer 742, the semiconductor layer 742 is electrically connected to the electrode 744a. In addition, in the other openings formed by selectively removing the portion of the insulating layer 741 overlapping the semiconductor layer 742, the semiconductor layer 742 is electrically connected to the electrode 744b. The region of the insulating layer 741 that overlaps the channel formation region can be used as a channel protection layer.

[0272] Figure 19B2 The transistor 821 shown is different from the transistor 820 in that the transistor 821 includes an electrode 723 on the insulating layer 729 that can be used as a back gate electrode.

[0273] By providing the insulating layer 729, the semiconductor layer 742 can be prevented from being exposed when the electrode 744a and the electrode 744b are formed. Therefore, the semiconductor layer 742 can be prevented from being thinned when the electrode 744a and the electrode 744b are formed.

[0274] In addition, the distance between the electrode 744a and the electrode 746 and the distance between the electrode 744b and the electrode 746 of the transistor 820 and the transistor 821 are longer than those of the transistor 810 and the transistor 811. Therefore, the parasitic capacitance generated between the electrode 744a and the electrode 746 can be reduced. In addition, the parasitic capacitance generated between the electrode 744b and the electrode 746 can be reduced. According to one embodiment of the present invention, a transistor with good electrical characteristics can be provided.

[0275] Fig.19C1 The transistor 825 shown is a channel-etched transistor which is one of the bottom-gate transistors. In the transistor 825, the electrode 744a and the electrode 744b are formed without using the insulating layer 741. Therefore, a portion of the semiconductor layer 742 exposed when the electrode 744a and the electrode 744b are formed is sometimes etched. On the other hand, since the insulating layer 741 is not provided, the productivity of the transistor can be improved.

[0276] Fig.19C2 The transistor 826 shown is different from the transistor 825 in that the transistor 826 has an electrode 723 which can serve as a back gate electrode over the insulating layer 729 .

[0277] 〔Top-gate transistor〕

[0278] Fig.20A1 The transistor 842 shown as an example is a top-gate transistor. In the transistor 842, electrodes 744a and 744b are formed after the insulating layer 729 is formed. The electrodes 744a and 744b are electrically connected to the semiconductor layer 742 through openings formed in the insulating layers 728 and 729.

[0279] In addition, a portion of the insulating layer 726 that does not overlap with the electrode 746 is removed, and Fig.20A3 As shown, the impurity 755 is introduced into the semiconductor layer 742 using the electrode 746 and the remaining insulating layer 726 as a mask, thereby forming an impurity region in the semiconductor layer 742 in a self-aligned manner. The transistor 842 includes a region where the insulating layer 726 extends beyond the end of the electrode 746. The impurity concentration of the region of the semiconductor layer 742 into which the impurity 755 is introduced through the insulating layer 726 is lower than that of the region into which the impurity 755 is not introduced through the insulating layer 726. An LDD (Lightly Doped Drain) region is formed in the region of the semiconductor layer 742 that does not overlap with the electrode 746.

[0280] Fig.20A2 The transistor 843 shown is different from the transistor 842 in that the transistor 843 includes an electrode 723 formed on a substrate 711. The electrode 723 has a region stacked with the semiconductor layer 742 via an insulating layer 772. The electrode 723 can function as a back gate electrode.

[0281] In addition, if Fig.20B1 The transistor 844 and Figure 20B2 As in the transistor 845 shown in FIG. 8 , the insulating layer 726 in the region not overlapping with the electrode 746 may be completely removed. Fig.20C1 The transistor 846 and Fig.20C2 As in the transistor 847 shown in the figure, the insulating layer 726 does not need to be removed.

[0282] In the transistors 843 to 847, after forming the electrode 746, the impurity 755 may be introduced into the semiconductor layer 742 using the electrode 746 as a mask, thereby forming an impurity region in a self-aligned manner in the semiconductor layer 742. According to one embodiment of the present invention, a transistor having excellent electrical characteristics can be realized.

[0283] This embodiment mode can be implemented in combination with the configurations described in other embodiment modes and the like as appropriate.

[0284] (Implementation 4)

[0285] In this embodiment, a configuration of a CAC (Cloud-Aligned Composite)-OS that can be used in a transistor disclosed in one embodiment of the present invention is described.

[0286] CAC-OS refers to, for example, a configuration in which elements contained in an oxide semiconductor are unevenly distributed, wherein the size of the material containing the unevenly distributed elements is greater than or equal to 0.5 nm and less than or equal to 10 nm, preferably greater than or equal to 1 nm and less than or equal to 2 nm, or a similar size. Note that in the following, a state in which one or more metal elements are unevenly distributed in an oxide semiconductor and regions containing the metal elements are mixed in a size of greater than or equal to 0.5 nm and less than or equal to 10 nm, preferably greater than or equal to 1 nm and less than or equal to 2 nm, is also referred to as a mosaic or patch shape.

[0287] In addition, the oxide semiconductor preferably contains at least indium. In particular, it preferably contains indium and zinc. In addition, it may also contain one or more selected from aluminum, gallium, yttrium, copper, vanadium, beryllium, boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten and magnesium.

[0288] For example, CAC-OS in In-Ga-Zn oxide (in CAC-OS, In-Ga-Zn oxide can be referred to as CAC-IGZO in particular) refers to a material divided into indium oxide (hereinafter referred to as InO X1 (X1 is a real number greater than 0)) or indium zinc oxide (hereinafter referred to as In X2 Zn Y2 O Z2 (X2, Y2 and Z2 are real numbers greater than 0) and gallium oxide (hereinafter referred to as GaO X3 (X3 is a real number greater than 0)) or gallium zinc oxide (hereinafter referred to as Ga X4 Zn Y4 O Z4 (X4, Y4 and Z4 are real numbers greater than 0)) etc. to form a mosaic shape, and the mosaic-shaped InO X1 or In X2 Zn Y2 O Z2 A structure uniformly distributed in the film (hereinafter also referred to as a cloud shape).

[0289] In other words, CAC-OS is a GaO X3 The area with In as the main component X2 Zn Y2 O Z2 or InO X1 In this specification, for example, when the atomic number ratio of In to element M in the first region is greater than that in the second region, the In concentration in the first region is higher than that in the second region.

[0290] Note that IGZO is a general term and sometimes refers to a compound containing In, Ga, Zn, and O. As a typical example, InGaO3(ZnO) m1 (m1 is a natural number) or In (1+x0) Ga (1-x0) O3(ZnO) m0 (-1≤x0≤1, m0 is an arbitrary number).

[0291] The crystalline compound has a single crystal structure, a polycrystalline structure or a CAAC structure. The CAAC structure is a crystal structure in which a plurality of IGZO nanocrystals have c-axis orientation and are connected in a non-oriented manner on the ab plane.

[0292] On the other hand, CAC-OS is related to the material composition of oxide semiconductors. CAC-OS refers to a composition in which nanoparticle-like regions with Ga as the main component are observed in a part of the material composition containing In, Ga, Zn, and O, and nanoparticle-like regions with In as the main component are observed in a part of the material composition, and are irregularly dispersed in a mosaic shape. Therefore, in CAC-OS, the crystal structure is a secondary factor.

[0293] Note that CAC-OS does not include a stacked-layer structure of two or more films having different compositions, for example, does not include a structure consisting of two layers of a film having In as a main component and a film having Ga as a main component.

[0294] Note that sometimes no GaO X3 The area with In as the main component X2 Zn Y2 O Z2 or InO X1 There are clear boundaries between the regions of the main components.

[0295] In the case where CAC-OS includes one or more selected from aluminum, yttrium, copper, vanadium, beryllium, boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten and magnesium instead of gallium, CAC-OS refers to a structure in which nanoparticle-like regions with the metal element as the main component are observed in a part and nanoparticle-like regions with In as the main component are observed in a part and are irregularly dispersed in a mosaic manner.

[0296] CAC-OS can be formed, for example, by sputtering without intentionally heating the substrate. When CAC-OS is formed by sputtering, one or more selected from an inert gas (typically argon), an oxygen gas, and a nitrogen gas can be used as a film-forming gas. In addition, the lower the flow rate ratio of the oxygen gas in the total flow rate of the film-forming gas during film formation, the better. For example, the flow rate ratio of the oxygen gas is set to be greater than 0% and less than 30%, preferably greater than 0% and less than 10%.

[0297] CAC-OS has the following characteristics: when measured by out-of-plane method using θ / 2θ scanning, which is one of the X-ray diffraction (XRD) measurement methods, no clear peak is observed. In other words, according to X-ray diffraction measurement, it can be seen that there is no orientation in the ab plane direction and c-axis direction in the measurement area.

[0298] In addition, in the electron diffraction pattern of CAC-OS obtained by irradiating an electron beam with a beam diameter of 1 nm (also called a nanobeam), a ring-shaped area with high brightness (ring-shaped area) and multiple bright spots in the ring-shaped area were observed. Therefore, according to the electron diffraction pattern, it can be seen that the crystalline structure of CAC-OS has an nc (nano-crystal) structure that is not oriented in the plane direction and the cross-sectional direction.

[0299] In addition, for example, in CAC-OS of In-Ga-Zn oxide, it can be confirmed from the EDX-mapping image obtained by energy dispersive X-ray spectroscopy (EDX) that there is GaO X3 The area with In as the main component X2 Zn Y2 O Z2 or InO X1 A composition in which the main components are unevenly distributed in the area.

[0300] The structure of CAC-OS is different from that of IGZO compounds in which metal elements are evenly distributed, and it has different properties from IGZO compounds. X3 The area with In as the main component X2 Zn Y2 O Z2 or InO X1 The regions with each element as the main component are separated from each other and the regions with each element as the main component have a mosaic-like structure.

[0301] Here, In X2 Zn Y2 O Z2 or InO X1 The conductivity of the area with GaO as the main component is higher than that of the area with GaO as the main component. X3 In other words, when the carrier flows through the region with In X2 Zn Y2 O Z2 or InO X1 When In is the main component of the region, it exhibits the conductivity of an oxide semiconductor. X2 Zn Y2 O Z2 or InO X1 When the region as the main component is distributed in a cloud-like manner in the oxide semiconductor, a high field-effect mobility (μ) can be achieved.

[0302] On the other hand, GaO X3 The insulation of the area with In as the main component is higher than that of the area with InX2 Zn Y2 O Z2 or InO X1 In other words, when GaO X3 When regions with the main components of MgO and the like are distributed in an oxide semiconductor, leakage current can be suppressed and good switching operation can be achieved.

[0303] Therefore, when CAC-OS is used in semiconductor devices, the X3 The insulation properties of etc. and the causes of In X2 Zn Y2 O Z2 or InO X1 The complementary effect of conductivity can achieve high on-state current (I on ) and high field effect mobility (μ).

[0304] In addition, semiconductor elements using CAC-OS have high reliability. Therefore, CAC-OS is suitable for use in various semiconductor devices such as displays.

[0305] This embodiment mode can be implemented in combination with the configurations described in other embodiment modes and the like as appropriate.

[0306] (Implementation 5)

[0307] In this embodiment, an electronic device in which a display device according to one embodiment of the present invention can be used is described with reference to the drawings.

[0308] Electronic devices that can use a display device in one embodiment of the present invention include display devices, personal computers, image storage devices and image reproduction devices with recording media, mobile phones, game consoles including portable game consoles, portable data terminals, e-book readers, imaging devices such as video cameras or digital cameras, goggle-type displays (head-mounted displays), navigation systems, audio reproduction devices (car audio systems, digital audio players, etc.), copiers, fax machines, printers, multifunction printers, automatic teller machines (ATMs), and vending machines. Figures 21A to 21F Specific examples of these electronic devices are shown.

[0309] Fig.21A An example of a television set 910 is shown, which includes a housing 911 , a display portion 912 , a speaker 913 , and the like. Fig.21A The structure in which the housing 911 is supported by a bracket 914 is shown.

[0310] The television device 910 can be operated by using a switch provided in the housing 911 or a remote control unit 915. In addition, a touch sensor may be provided on the display unit 912 so that the television device can be operated by touching the display unit 912 with a finger or the like. The remote control unit 915 may also include a display unit that displays information output from the remote control unit 915. By using the operation keys or the touch panel provided on the remote control unit 915, the channel and volume can be operated, and the image displayed on the display unit 912 can be operated.

[0311] In addition, the television device 910 may include a receiver and a modem. General television broadcasts can be received by using the receiver. Furthermore, when the television device is connected to a wired or wireless communication network via a modem, one-way (from a sender to a receiver) or two-way (between a sender and a receiver or between receivers, etc.) information communication can be performed.

[0312] The television set 910 can use the display device of one embodiment of the present invention as the display portion 912. Thus, a high-quality image can be displayed on the display portion 912.

[0313] Fig. 21B An example of a wristwatch-type information terminal 920 is shown, which includes a housing and wristband 921, a display unit 922, operation buttons 923, an external connection port 924, a camera 925, etc. The display unit 922 is provided with a touch panel for operating the information terminal 920. The housing and wristband 921 and the display unit 922 are flexible and suitable for being worn on the body.

[0314] The information terminal 920 can use the display device of one embodiment of the present invention as the display portion 922. Thus, a high-quality image can be displayed on the display portion 922.

[0315] Fig. 21C An example of a digital camera 930 is shown, which is equipped with a viewfinder 931. The digital camera 930 includes a housing 932, a display portion 933, operation buttons 934, a shutter button 935, and the like. In addition, the digital camera 930 also includes a detachable lens 936. In addition, the lens 936 may not be detachable.

[0316] The digital camera 930 can perform photographing by pressing the shutter button 935. In addition, the display portion 933 may have a touch panel function. In this case, photographing can be performed by touching the display portion 933.

[0317] The housing 932 includes an embedder having electrodes, and can be connected to a flash device or the like in addition to the viewfinder 931 .

[0318] The viewfinder 931 includes a housing 937 , a display portion 938 , and the like.

[0319] The housing 937 includes an embedder that is fitted into the embedder of the digital camera 930, and the viewfinder 931 can be attached to the digital camera 930. In addition, the embedder includes electrodes, and an image corresponding to image data supplied from the digital camera 930 can be displayed on the display portion 938.

[0320] The display device of one embodiment of the present invention can be used for the display portion 933 of the digital camera 930 and the display portion 938 of the viewfinder 931. Thus, the display portion 933 and the display portion 938 can display high-quality images.

[0321] Fig.21D This is an example of a digital signage 940 . A pillar 943 is provided between a floor 941 and a ceiling 942 , and a display unit 944 is installed along a curved surface of the pillar 943 .

[0322] The wider the display unit 944 is, the more information can be provided at one time. In addition, the wider the display unit 944 is, the easier it is to attract people's attention, for example, the advertising effect can be improved.

[0323] By using a touch panel for the display portion 944 , not only can an image be displayed on the display portion 944 but also a user can perform an intuitive operation, which is preferable.

[0324] The digital signage 940 can use the display device of one embodiment of the present invention in the display unit 944 , thereby being able to display a high-quality image on the display unit 944 .

[0325] Fig.21E An example of a mobile phone 950 is shown, which includes a housing 951, a display unit 952, an operation button 953, an external connection port 954, a speaker 955, a slot 956, a camera 957, an earphone jack 958, and the like. The mobile phone 950 may be provided with a touch sensor on the display unit 952. All operations such as making a call and inputting text can be performed by touching the display unit 952 with a finger or a stylus pen. In addition, various removable storage devices such as a memory card such as an SD card, a USB memory, and an SSD (Solid State Drive) can be inserted into the slot 956.

[0326] The mobile phone 950 can use the display device of one embodiment of the present invention as the display portion 952. Thus, high-quality images can be displayed on the display portion 952.

[0327] Fig.21FAn example of a portable data terminal 960 is shown, which includes a housing 961, a display unit 962, a speaker 963, a camera 964, etc. Information can be input and output by using the touch panel function of the display unit 962. In addition, text and the like can be recognized from an image obtained by the camera 964, and the text can be output as a voice using the speaker 963.

[0328] The portable data terminal 960 can use the display device of one embodiment of the present invention as the display portion 962. Thus, a high-quality image can be displayed on the display portion 962.

[0329] This embodiment mode can be implemented in combination with the configurations described in other embodiment modes and the like as appropriate.

[0330] [Explanation of symbols]

[0331] 10: pixel, 11: transistor, 12: transistor, 13: transistor, 14: transistor, 15: transistor, 16: transistor, 20: display element, 21: capacitor, 22: capacitor, 23: capacitor, 31: wiring, 32: wiring, 35: wiring, 36: wiring, 41: wiring, 42: wiring, 45: wiring, 50: wiring, 53: wiring, 54: wiring, 60: display device, 61: display unit, 62: gate drive circuit, 63: data drive circuit, 64: current detection circuit, 65: correction data generation circuit, 66: storage device, 67: storage device, 215: display unit, 221: gate drive circuit, 231: data drive circuit, 232: data drive circuit , 241: power supply circuit, 723: electrode, 726: insulating layer, 728: insulating layer, 729: insulating layer, 736: coloring layer, 741: insulating layer, 742: semiconductor layer, 744a: electrode, 744b: electrode, 746: electrode, 755: impurity, 771: substrate, 772: insulating layer, 775: n-type semiconductor layer, 777: light-emitting layer, 779: p-type semiconductor layer, 781: semiconductor layer, 782: display element, 783: electrode layer, 785: electrode layer, 787: electrode layer, 789: insulating layer, 791: bump, 793: bump, 795: light shielding layer, 797: phosphor layer, 810: transistor, 811: transistor, 820: transistor, 821: transistor, 825: transistor, 826: transistor, 842: transistor, 843: transistor, 844: transistor, 845: transistor, 846: transistor, 847: transistor, 910: television set, 911: casing, 912: display unit, 913: speaker, 914: stand, 915: remote control unit, 920: information terminal, 921: casing and wristband, 922: display unit, 923: operation button, 924: external connection port, 925: camera, 930: digital camera, 931: viewfinder, 932: casing, 933: display unit, 934: operation button, 935: shutter button, 936: lens, 937: casing, 938: display unit, 940: digital Signage, 941: Floor, 942: Ceiling, 943: Pillar, 944: Display, 950: Mobile Phone, 951: Housing, 952: Display, 953: Operation Button, 954: External Connection Port, 955: Speaker, 956: Slot, 957: Camera, 958: Headphone Jack, 960: Portable Information Terminal, 961: Housing, 962: Display, 963: Speaker, 964: Camera, 4001: Substrate, 4005: Sealant, 4006: Substrate, 4010: Transistor, 4011: Transistor, 4014: Wiring, 4015: Electrode, 4017: Electrode, 4018: FPC, 4019: Anisotropic Conductive Layer, 4020: Capacitor,4021: electrode, 4030: electrode layer, 4031: electrode layer, 4041: printed wiring board, 4042: integrated circuit, 4102: insulating layer, 4103: insulating layer, 4110: insulating layer, 4111: insulating layer, 4112: insulating layer, 4200: input device, 4210: touch panel, 4227: electrode, 4228: electrode, 4237: wiring, 4238: wiring, 4239: wiring, 4263: substrate, 4272: FPC, 4273: IC, 4301: coloring layer, 4302: light shielding layer, 4510: partition wall, 4511: light emitting layer, 4513: light emitting element, 4514: filler,

Claims

1. A method for operating a display device, The display device includes a pixel including a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, a capacitor, and a display element, and a correction data generation circuit. in, One of the source and the drain of the first transistor is electrically connected to one electrode of the capacitor, The other of the source and the drain of the first transistor is electrically connected to a first wiring. wherein one of the source and the drain of the second transistor is electrically connected to the other electrode of the capacitor, The other of the source and the drain of the second transistor is electrically connected to a second wiring. wherein the other electrode of the capacitor is electrically connected to the gate of the third transistor, wherein one of the source and the drain of the third transistor is electrically connected to an electrode of the display element, The other of the source and the drain of the third transistor is electrically connected to a third wiring. wherein one of the source and the drain of the fourth transistor is electrically connected to the one electrode of the display element, The other of the source and the drain of the fourth transistor is electrically connected to a fourth wiring. Wherein, one of the source and the drain of the fifth transistor is electrically connected to the back gate of the third transistor, The other of the source and the drain of the fifth transistor is electrically connected to a fifth wiring. wherein the gate of the first transistor is electrically connected to the gate of the fourth transistor, The working method comprises: In a first period, the correction data generation circuit generates correction data as data for correcting a threshold voltage of the third transistor. During the second period, the first potential is supplied to the other electrode of the capacitor, During a third period, the second potential is supplied to one electrode of the capacitor so that the potential of the other electrode of the capacitor becomes a third potential. And in the fourth period, by turning off the first transistor and the fourth transistor, a current corresponding to the third potential flows through the display element.

2. The operating method of the display device according to claim 1, In the first period, the correction data generation circuit generates the correction data, and then supplies a potential corresponding to the correction data to the back gate of the third transistor.

3. The operating method of the display device according to claim 1, in, During the first period, the fourth transistor is turned on so that a current flows through the third and fourth transistors, and the correction data generation circuit generates the correction data corresponding to the current.

4. The operating method of the display device according to claim 3, In the first period, the correction data generation circuit generates the correction data so that the current flowing through the third transistor becomes equal to or less than a certain value.

5. The operating method of the display device according to claim 1, wherein the second transistor includes a metal oxide in a channel formation region, The metal oxide contains In, Zn, and M, wherein M is Al, Ti, Ga, Ge, Sn, Y, Zr, La, Ce, Nd, or Hf.

6. The operating method of the display device according to claim 1, The display element is an organic EL element.

Images