44results about How to "Luminance variation" patented technology

To provide a display device and a driving method thereof, where variations in the threshold voltage of transistors can be compensated and thus variations in luminance of light-emitting elements can be suppressed. In a first period, initialization is performed; in a second period, a voltage based on the threshold voltage of a first transistor is held in first and second storage capacitors; in a third period, a voltage based on a video signal voltage and the threshold voltage of the first transistor is held in the first and second storage capacitors; and in a fourth period, voltages held in the first and second storage capacitors are applied to a gate terminal of the first transistor to supply a current to a light-emitting element, so that the light-emitting element emits light. Through the operation process, a current obtained by compensating variations in the threshold voltage of the first transistor can be supplied to the light-emitting element, thereby variations in luminance can be suppressed.

An active matrix light emitting device of which luminance characteristic does not vary among light emitting elements of respective pixels, and which can be realized even when a panel has higher definition is provided. In the light emitting device, one electrode (a second electrode) of the light emitting element having a layer containing a light emitting material interposed between a first electrode and the second electrode is electrically connected to an auxiliary wiring not only in a peripheral portion but also in a pixel portion. The layer containing a light emitting material has at least a first buffer layer, a light emitting layer, and a second buffer layer. In the pixel portion, either one or both of the first buffer layer and the second buffer layer are interposed between the auxiliary wiring (the first auxiliary wiring) and the second electrode in a connection portion (a first connection portion) where the second electrode and the auxiliary wiring (the first auxiliary wiring) are electrically connected.

A display device which can compensate for variations of the threshold voltage of transistors and suppress variations in luminance, and a driving method thereof are provided. Current is supplied to a light emitting element and light is emitted from the light emitting element by following steps: in the first period initial voltage is stored in a storage capacitor; in the second period, voltage based on video signal voltage and the threshold voltage of the transistor is stored in the storage capacitor; and in the third period, the voltage stored in the storage capacitor in the second period is applied to a gate electrode of the transistor. By these operation processes, the current which compensates the effect of the variations of the threshold voltage of the transistor can be supplied to the light emitting element. Therefore, variations in luminance are suppressed.

A liquid crystal display device is provided which is capable of improving quality of moving images. A field dividing driving operation is performed in which an odd field during which each of scanning electrodes in odd-numbered rows is sequentially driven and an even field during which each of scanning electrodes in even-numbered rows is sequentially driven occur, alternately and repeatedly, with time width of a refresh rate. In the former half of the odd field, display data is written in each of pixel regions corresponding to scanning electrodes in odd-numbered rows and, in the latter half of the odd field, black data is written in each of the pixel regions corresponding to scanning electrodes in the odd-numbered rows. In the former half of the even field, display data is written in each of pixel regions corresponding to scanning electrodes in the even-numbered rows and, in the latter half of the even field, black data is written in each of pixel regions corresponding to scanning electrodes in the even-numbered rows.

In a light-emitting device, supply of current is controlled using a transistor having a normal gate electrode (a first gate electrode) and a second gate electrode for controlling threshold voltage. The light-emitting device comprises one or more switches for selecting conduction or non-conduction between the first gate electrode and a drain terminal of the transistor. When the threshold voltage of the transistor is acquired, the first gate electrode and the drain terminal of the transistor are brought into conduction with the switch, and the threshold voltage of the transistor is shifted by controlling the potential of the second gate electrode.

A structure of an EL display device which has an increased display area is provided. Further, a structure of an EL display device which has a high definition display is provided. An auxiliary electrode is formed over a first partition and side surfaces of the auxiliary electrode are covered with a second partition. A top surface of the auxiliary electrode is in contact with the conductive film which is one electrode of a light-emitting element and has a light-transmitting property, which enables a large-area display. Further, even the distance between the adjacent light-emitting elements is shortened, the auxiliary electrode can be provided between the adjacent light-emitting elements, which enables a high definition display.

A light emitting device capable of suppressing drop in luminance or luminance unevenness of a light emitting element due to deterioration of an electro luminescent material and capable of switching an image direction vertically to horizontally without a frame memory additionally provided. The light emitting device of the invention comprises in each pixel first to fourth transistors, a light emitting element, and a signal line. The first transistor and the second transistor control the connection between the signal line and a gate of the third transistor, the fourth transistor controls a current value supplied to the light emitting element, and the third transistor selects whether the current is supplied to the light emitting element or not. Further, the first transistor and the second transistor are switched separately.

A display device which can compensate for variations of the threshold voltage of transistors and suppress variations in luminance, and a driving method thereof are provided. Current is supplied to a light emitting element and light is emitted from the light emitting element by following steps: in the first period initial voltage is stored in a storage capacitor; in the second period, voltage based on video signal voltage and the threshold voltage of the transistor is stored in the storage capacitor; and in the third period, the voltage stored in the storage capacitor in the second period is applied to a gate electrode of the transistor. By these operation processes, the current which compensates the effect of the variations of the threshold voltage of the transistor can be supplied to the light emitting element. Therefore, variations in luminance are suppressed.

No need of lowering off-current of a switching transistor, fewer luminance variations of a light emitting element between pixels due to characteristic variations of a driving transistor, and less risk of steps due to increase in the number of wirings. A video signal for light emission or non-emission of a pixel is input to a gate of a current controlling transistor operated in a linear region, which is connected in series with the driving transistor, through a switching transistor. Since a voltage Vds between a source and a drain of the current controlling transistor is small, small changes in a voltage Vgs between a gate and a source thereof do not affect a current flowing in a load. The current flowing in the light emitting element is determined by the driving transistor operated in a saturation region, and a fixed potential is input to the gate thereof during light emission.

A light-emitting device according to one embodiment of the present invention includes a light-emitting element, a first transistor whose source is electrically connected to an anode of the light-emitting element, a second transistor which controls whether an image signal is input to a gate of the first transistor, a third transistor which controls electrical connection and disconnection between the gate and a drain of the first transistor, a fourth transistor which controls whether a first power supply potential is supplied to the drain of the first transistor, a fifth transistor which controls whether a second power supply potential is supplied to the anode of the light-emitting element, a first capacitor which holds a voltage between the gate and the source of the first transistor, and a second capacitor electrically connected in series with the first capacitor and electrically connected in series with the light-emitting element.

A semiconductor device in which electrostatic discharge damage during manufacturing steps is prevented. More specifically, a semiconductor device in which electrostatic discharge damage during a step in which the formation of a pixel electrode is completed is prevented. A semiconductor device of the invention comprises a light emitting element, a driving transistor and a protection means disposed between the light emitting element and the driving transistor. The protection means comprises as least one of a resistor element, a capacitor element and a rectifier element. More specifically, the protection means is disposed between a pixel electrode of the light emitting element and a source electrode or a drain electrode of the driving transistor. It is to be noted that the rectifier element is an element having a rectifying function and corresponds to a diode or a transistor whose drain electrode and gate electrode are connected to each other.

A light emitting device capable of suppressing drop in luminance or luminance unevenness of a light emitting element due to deterioration of an electro luminescent material and capable of switching an image direction vertically to horizontally without a frame memory additionally provided. The light emitting device of the invention comprises in each pixel first to fourth transistors, a light emitting element, and a signal line. The first transistor and the second transistor control the connection between the signal line and a gate of the third transistor, the fourth transistor controls a current value supplied to the light emitting element, and the third transistor selects whether the current is supplied to the light emitting element or not. Further, the first transistor and the second transistor are switched separately.

Disclosed is an organic EL display device which includes a light emitter; a current controller controlling a current to be fed to the light emitter; a current detector detecting a value of current flowing through the light emitter as a voltage; a first switching unit switching between transmission and non-transmission of a voltage value corresponding to the detected current; a comparison amplifier comparing and amplifying the voltage value transmitted from the first switching unit to a voltage value corresponding to the image signal; a second switching unit switching between transmission and non-transmission of the voltage value being a result of the comparison and amplification; and an image signal holding capacitor charged / discharged based on the voltage value transmitted from the second switching unit, the current controller controlling the current to be fed to the light emitter based on a charging voltage of the image signal holding capacitor.

A driving device includes a first switch element to switch between applying or not applying to a light-emitting element a voltage directed to setting the light-emitting element in an ON state, and a constant current control circuit to adjust a current flowing through the light-emitting element when the light-emitting element is in an ON state to a predetermined current value.

Disclosed is an organic EL display device which includes a light emitter; a current controller controlling a current to be fed to the light emitter; a current detector detecting a value of current flowing through the light emitter as a voltage; a first switching unit switching between transmission and non-transmission of a voltage value corresponding to the detected current; a comparison amplifier comparing and amplifying the voltage value transmitted from the first switching unit to a voltage value corresponding to the image signal; a second switching unit switching between transmission and non-transmission of the voltage value being a result of the comparison and amplification; and an image signal holding capacitor charged / discharged based on the voltage value transmitted from the second switching unit, the current controller controlling the current to be fed to the light emitter based on a charging voltage of the image signal holding capacitor.

A small switch having a liquid crystal display includes an operation button; a liquid crystal display device having a liquid crystal panel for displaying information including characters and / or pictures on the operation button and a printed circuit board on which an IC chip, which serves as a driver circuit for the liquid crystal panel, is mounted, the liquid crystal display device being housed in the operation button; a switch body including a contact mechanism for opening and closing an electrical path by vertically moving the operation button; and backlight sources having different colors. The liquid crystal panel is an antiferroelectric liquid crystal panel. The backlight sources are sequentially turned on at high speed below the antiferroelectric liquid crystal panel, and liquid crystal screens having different display contents for every color are displayed in synchronization with the turning on of the backlight sources to achieve multicolor display.

A license plate lamp for radiating light to a surface of a license plate attached to a rear end of a vehicle body includes: a lamp body disposed above the license plate; a light emitting diode disposed within the lamp body, the light emitting diode having an optical axis extending in a vertical direction for emitting light toward a license plate located under the light emitting diode; and a control lens provided between the light emitting diode and the license plate for controlling the light emitted by the light emitting diode so that the light is radiated toward a surface of the license plate. The control lens includes a first control portion for radiating the light emitted by the light emitting diode toward an upper end part of the surface of the license plate, and a second control portion located rearward of the first control portion for radiating the light emitted by the light emitting diode toward substantially a whole region of the surface of the license plate.

A liquid crystal display has a light guide plate having a light-emitting plane on its one end surface, a light source arranged on a side surface of the light guide plate, and a liquid crystal panel arranged opposite the light-emitting plane of the light guide plate. Deflection patterns are formed on a surface opposite the light-emitting plane of the light guide plate, and the deflection patterns are arranged so that two independent components on the surface opposite the light-emitting plane of the light guide plate are random. In a certain region on the surface opposite the light-emitting plane, when an average value of the number of the deflection patterns included in each region opposite each pixel of the liquid crystal panel is designated by μn and a standard deviation is designated by σn, their ratio satisfies the relationship: 0<σn / μn≦0.154. Light from the light source introduced into the light guide plate is deflected towards the light-emitting plane by the deflection patterns so as to be emitted from the light-emitting plane. The liquid crystal panel is illuminated by the light emitted from the light-emitting plane.

A light-emitting element has a property that a resistance value (internal resistance) changes in accordance with an environmental temperature. It is an object to downsize a monitoring element which corrects an influence of variations in current value of the light-emitting element, which are caused by an environmental temperature change and a change with time. A pixel includes a plurality of sub-pixels, areas of light-emitting elements provided in the individual sub-pixels are made to be different from each other, and an area of a monitoring element is made to be the same as an area of the light-emitting element in any of the sub-pixels, thereby correcting light-emission of the pixel by the monitoring element.

No need of lowering off-current of a switching transistor, fewer luminance variations of a light emitting element between pixels due to characteristic variations of a driving transistor, and less risk of steps due to increase in the number of wirings. A video signal for light emission or non-emission of a pixel is input to a gate of a current controlling transistor operated in a linear region, which is connected in series with the driving transistor, through a switching transistor. Since a voltage Vds between a source and a drain of the current controlling transistor is small, small changes in a voltage Vgs between a gate and a source thereof do not affect a current flowing in a load. The current flowing in the light emitting element is determined by the driving transistor operated in a saturation region, and a fixed potential is input to the gate thereof during light emission.

Power consumption required for charging and discharging a source signal line is reduced in an active matrix EL display device. A bipolar transistor (Bi1) has a base terminal B connected to an output terminal c1 of an operational amplifier (OP1), a collector terminal C connected to a low power potential (GND), and an emitter terminal E connected to a resistor R2. A high power potential (VBH) is a potential in synchronization with a high power potential of a light emitting element. A potential of the output terminal c1 of the operational amplifier (OP1) is outputted as a buffer low power potential (VBL). The low power potential (VBL) corresponds to a potential difference between the high power potential (VBH) and a high power potential (V1). Accordingly, the low power potential (VBL) can follow the high power potential (VBH), that is a high power potential of the light emitting element.