Method of driving display device
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorJun Koyama
Life of this patent
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Abstract
An active matrix type EL display device is provided, which is capable of suppressing the unevenness of luminance display due to the unevenness of the characteristics of TFTs which constitute pixels, or due to variations in the environmental temperature at which the display device is used. The active matrix type EL display is driven by a time gray scale method, and is capable of keeping the drain current of each of its EL driving TFTs constant by operating each of the EL driving TFTs in a saturation region in an ON state. Accordingly, constant current can be made to flow in each of the EL elements, whereby it is possible to provide an active matrix type EL display device with accurate gray scale display and high image quality.
Claims30
A display device comprising:
- a driver circuit;
- and
- a pixel electrically connected to the driver circuit, the pixel comprising:
- a first thin film transistor;
- a second thin film transistor;
- a resistor;
- an EL element;
- and
- a color filter,
- wherein a gate of the first thin film transistor is electrically connected to a first line,
- wherein one of a source and a drain of the first thin film transistor is electrically connected to a second line,
- wherein the other of the source and the drain of the first thin film transistor is electrically connected to a gate of the second thin film transistor,
- wherein one of a source and a drain of the second thin film transistor is electrically connected to a third line,
- wherein the other of the source and the drain of the second thin film transistor is electrically connected to the EL element,
- wherein the resistor is electrically connected to the second thin film transistor in series between the third line and the EL element,
- wherein the EL element is capable of emitting green light,
- wherein the color filter is capable of extracting green light,
- wherein the EL element overlaps with the first thin film transistor and the second thin film transistor, and
- wherein the first line is a gate line.
A display device comprising:
- a pixel comprising:
- a first thin film transistor;
- a second thin film transistor;
- a resistor;
- an EL element;
- and
- a color filter,
- wherein a gate of the first thin film transistor is electrically connected to a first line,
- wherein one of a source and a drain of the first thin film transistor is electrically connected to a second line,
- wherein the other of the source and the drain of the first thin film transistor is electrically connected to a gate of the second thin film transistor,
- wherein one of a source and a drain of the second thin film transistor is electrically connected to a third line,
- wherein the other of the source and the drain of the second thin film transistor is electrically connected to the EL element,
- wherein the resistor is electrically connected to the second thin film transistor in series between the third line and the EL element,
- wherein the EL element is capable of emitting green light,
- wherein the color filter is capable of extracting green light,
- wherein the EL element overlaps with the first thin film transistor and the second thin film transistor, and
- wherein the first line is a gate line.
A display device comprising:
- a pixel comprising:
- a first thin film transistor;
- a second thin film transistor;
- a resistor;
- an EL element overlapping with the first thin film transistor and the second thin film transistor;
- and a color filter over the EL element,
- wherein a gate of the first thin film transistor is electrically connected to a first line,
- wherein one of a source and a drain of the first thin film transistor is electrically connected to a second line,
- wherein the other of the source and the drain of the first thin film transistor is electrically connected to a gate of the second thin film transistor,
- wherein one of a source and a drain of the second thin film transistor is electrically connected to a power supply line third line,
- wherein the other of the source and the drain of the second thin film transistor is electrically connected to the EL element,
- wherein the resistor is electrically connected to the second thin film transistor in series between the power supply line third line and the EL element,
- wherein the EL element is capable of emitting green light,
- wherein the color filter is capable of extracting green light, and
- wherein the first line is a gate line.
Dependencies are inferred from the claim text.