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US 7,609,236 B2Granted
Display device and method of driving the same
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorJun Koyama
Life of this patent
Estimating the term…
Abstract
A display is conducted by using a time gray-scale system, in which one frame period is divided into a plurality of sub-frame periods, and a voltage applied to an EL element of a pixel is varied on a sub-frame period basis. Because of this, a display device is provided in which the fluctuations in brightness caused by an environment temperature of an EL element are suppressed with a gray-scale display method that is unlikely to be influenced by variations in characteristics of TFTs in a pixel portion and that is unlikely to be influenced by variations in a display period.
Claims19
A display device comprising:
- a pixel portion formed over a substrate, the pixel portion having a light emitting element, wherein the light emitting element comprises a first electrode and a second electrode with a light emitting material interposed therebetween;
- a monitoring light emitting element electrically connected to the light emitting element through a power source line;
- and
- a plurality of constant current sources,
- wherein the monitoring light emitting element comprises the light emitting material interposed between a pair of electrodes,
- wherein any one of the plurality of constant current sources is electrically connected to the monitoring light emitting element through a switch, and
- wherein a brightness change of the light emitting element caused by a temperature change of the light emitting material interposed between the first electrode and the second electrode is suppressed by using the monitoring light emitting element.
4 more elements
A display device comprising:
- a pixel portion formed over a substrate, the pixel portion having a light emitting element, wherein the light emitting element comprises a first electrode and a second electrode with a light emitting material interposed therebetween;
- a monitoring light emitting element electrically connected to the light emitting element through a power source line;
- and
- a plurality of constant current sources,
- wherein the monitoring light emitting element comprises the light emitting material interposed between a pair of electrodes,
- wherein any one of the plurality of constant current sources is electrically connected to the monitoring light emitting element through a switch, and
- wherein a brightness increase of the light emitting element caused by a temperature change of the light emitting material interposed between the first electrode and the second electrode is suppressed by using the monitoring light emitting element.
4 more elements
A display device comprising:
- a pixel portion formed over a substrate, the pixel portion having a light emitting element, wherein the light emitting element comprises a first electrode and a second electrode with a light emitting material interposed therebetween;
- and
- a buffer amplifier, a monitoring light emitting element, and a plurality of constant current sources,
- wherein the monitoring light emitting element comprises the light emitting material interposed between a pair of electrodes,
- wherein the monitoring light emitting element and an input terminal of the buffer amplifier are electrically connected to any one of the plurality of constant current sources through a switch,
- wherein an output terminal of the buffer amplifier is electrically connected to the light emitting element, and
- wherein a brightness change of the light emitting element caused by a temperature change of the light emitting material interposed between the first electrode and the second electrode is suppressed by using the monitoring light emitting element.
4 more elements
A display device comprising:
- a pixel portion formed over a substrate, the pixel portion having a light emitting element, wherein the light emitting element comprises a first electrode and a second electrode with a light emitting material interposed therebetween;
- and
- a buffer amplifier, a monitoring light emitting element, and a plurality of constant current sources,
- wherein the monitoring light emitting element comprises the light emitting material interposed between a pair of electrodes,
- wherein the monitoring light emitting element and an input terminal of the buffer amplifier are electrically connected to any one of the plurality of constant current sources through a switch,
- wherein an output terminal of the buffer amplifier is electrically connected to the light emitting element, and
- wherein a brightness increase of the light emitting element caused by a temperature change of the light emitting material interposed between the first electrode and the second electrode is suppressed by using the monitoring light emitting element.
4 more elements
A display device comprising:
- a pixel portion formed over a substrate, the pixel portion having a light emitting element, wherein the light emitting element comprises a first electrode and a second electrode with a light emitting material interposed therebetween;
- and
- a buffer amplifier, a monitoring light emitting element, and a plurality of constant current sources,
- wherein the monitoring light emitting element comprises the light emitting material interposed between a pair of electrodes,
- wherein the monitoring light emitting element and an input terminal of the buffer amplifier are electrically connected to any one of the plurality of constant current sources through a switch,
- wherein an output terminal of the buffer amplifier is electrically connected to the light emitting element through a power source line, and
- wherein a brightness change of the light emitting element caused by a temperature change of the light emitting material interposed between the first electrode and the second electrode is suppressed by using the monitoring light emitting element.
4 more elements
A display device comprising:
- a pixel portion formed over a substrate, the pixel portion having a light emitting element, wherein the light emitting element comprises a first electrode and a second electrode with a light emitting material interposed therebetween;
- and
- a buffer amplifier, a monitoring light emitting element, and a plurality of constant current sources,
- wherein the monitoring light emitting element comprises the light emitting material interposed between a pair of electrodes,
- wherein the monitoring light emitting element and an input terminal of the buffer amplifier are electrically connected to any one of the plurality of constant current sources through a switch,
- wherein an output terminal of the buffer amplifier is electrically connected to the light emitting element through a power source line, and
- wherein a brightness increase of the light emitting element caused by a temperature change of the light emitting material interposed between the first electrode and the second electrode is suppressed by using the monitoring light emitting element.
4 more elements
A display device comprising:
- a pixel portion formed over a substrate, the pixel portion having a light emitting element, wherein the light emitting element comprises a first electrode and a second electrode with a light emitting material interposed therebetween;
- a monitoring light emitting element electrically connected to the light emitting element through a power source line;
- and
- a plurality of constant current sources,
- wherein the monitoring light emitting element comprises the light emitting material interposed between a pair of electrodes,
- wherein any one of the plurality of constant current sources is electrically connected to the monitoring light emitting element through a switch,
- wherein a brightness change of the light emitting element caused by a temperature change of the light emitting material interposed between the first electrode and the second electrode is suppressed by using the monitoring light emitting element, and
- wherein a current flowing into the monitoring light emitting element is equal to a current flowing into the light emitting element.
5 more elements
A display device comprising:
- a pixel portion formed over a substrate, the pixel portion having a light emitting element, wherein the light emitting element comprises a first electrode and a second electrode with a light emitting material interposed therebetween;
- a monitoring light emitting element electrically connected to the light emitting element through a power source line;
- and
- a plurality of constant current sources,
- wherein the monitoring light emitting element comprises the light emitting material interposed between a pair of electrodes,
- wherein any one of the plurality of constant current sources is electrically connected to the monitoring light emitting element through a switch,
- wherein a brightness increase of the light emitting element caused by a temperature change of the light emitting material interposed between the first electrode and the second electrode is suppressed by using the monitoring light emitting element, and
- wherein a current flowing into the monitoring light emitting element is equal to a current flowing into the light emitting element.
5 more elements
A display device comprising:
- a pixel portion formed over a substrate, the pixel portion having a light emitting element, wherein the light emitting element comprises a first electrode and a second electrode with a light emitting material interposed therebetween;
- and
- a buffer amplifier, a monitoring light emitting element, and a plurality of constant current sources,
- wherein the monitoring light emitting element comprises the light emitting material interposed between a pair of electrodes,
- wherein the monitoring light emitting element and an input terminal of the buffer amplifier are electrically connected to any one of the plurality of constant current sources through a switch,
- wherein an output terminal of the buffer amplifier is electrically connected to the light emitting element,
- wherein a brightness change of the light emitting element caused by a temperature change of the light emitting material interposed between the first electrode and the second electrode is suppressed by using the monitoring light emitting element, and
- wherein a current flowing into the monitoring light emitting element is equal to a current flowing into the light emitting element.
5 more elements
A display device comprising:
- a pixel portion formed over a substrate, the pixel portion having a light emitting element, wherein the light emitting element comprises a first electrode and a second electrode with a light emitting material interposed therebetween;
- and
- a buffer amplifier, a monitoring light emitting element, and a plurality of constant current sources,
- wherein the monitoring light emitting element comprises the light emitting material interposed between a pair of electrodes,
- wherein the monitoring light emitting element and an input terminal of the buffer amplifier are electrically connected to any one of the constant current sources through a switch,
- wherein an output terminal of the buffer amplifier is electrically connected to the light emitting element,
- wherein a brightness increase of the light emitting element caused by a temperature change of the light emitting material interposed between the first electrode and the second electrode is suppressed by using the monitoring light emitting element, and
- wherein a current flowing into the monitoring light emitting element is equal to a current flowing into the light emitting element.
5 more elements
A display device comprising:
- a pixel portion formed over a substrate, the pixel portion having a light emitting element, wherein the light emitting element comprises a first electrode and a second electrode with a light emitting material interposed therebetween;
- and
- a buffer amplifier, a monitoring light emitting element, and a plurality of constant current sources,
- wherein the monitoring light emitting element comprises the light emitting material interposed between a pair of electrodes,
- wherein the monitoring light emitting element and an input terminal of the buffer amplifier are electrically connected to any one of the plurality of constant current sources through a switch,
- wherein an output terminal of the buffer amplifier is electrically connected to the light emitting element through a power source line,
- wherein a brightness change of the light emitting element caused by a temperature change of the light emitting material interposed between the first electrode and the second electrode is suppressed by using the monitoring light emitting element, and
- wherein a current flowing into the monitoring light emitting element is equal to a current flowing into the light emitting element.
5 more elements
A display device comprising:
- a pixel portion formed over a substrate, the pixel portion having a light emitting element, wherein the light emitting element comprises a first electrode and a second electrode with a light emitting material interposed therebetween;
- and
- a buffer amplifier, a monitoring light emitting element, and a plurality of constant current sources,
- wherein the monitoring light emitting element comprises the light emitting material interposed between a pair of electrodes,
- wherein the monitoring light emitting element and an input terminal of the buffer amplifier are electrically connected to any one of the plurality of constant current sources through a switch,
- wherein an output terminal of the buffer amplifier is electrically connected to the light emitting element through a power source line,
- wherein a brightness increase of the light emitting element caused by a temperature change of the light emitting material interposed between the first electrode and the second electrode is suppressed by using the monitoring light emitting element, and
- wherein a current flowing into the monitoring light emitting element is equal to a current flowing into the light emitting element.
5 more elements
Dependencies are inferred from the claim text.