Display device and method of driving the same
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorJun Koyama
Life of this patent
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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.
Claims30
A light emitting device comprising:
- a first light emitting element formed over a substrate, the first light emitting element comprising a first electrode and a second electrode with a first light emitting material interposed therebetween;
- a second light emitting element comprising a third electrode and a fourth electrode with the first light emitting material interposed therebetween;
- a plurality of constant current sources;
- and
- a switch which is arranged to connect the third electrode to one of the plurality of constant current sources,
- wherein the third electrode is electrically connected to the first electrode through a power source line.
A light emitting device comprising:
- a first light emitting element formed over a substrate, the first light emitting element comprising a first electrode and a second electrode with a first light emitting material interposed therebetween;
- a second light emitting element comprising a third electrode and a fourth electrode with the first light emitting material interposed therebetween;
- a plurality of constant current sources;
- and
- a switch which is arranged to connect the third electrode to one of the plurality of constant current sources,
- wherein the third electrode is electrically connected to the first electrode through a buffer amplifier and a power source line.
An electronic device having a light emitting portion, the light emitting portion comprising:
- a first light emitting element formed over a substrate, the first light emitting element comprising a first electrode and a second electrode with a first light emitting material interposed therebetween;
- a second light emitting element comprising a third electrode and a fourth electrode with the first light emitting material interposed therebetween;
- a plurality of constant current sources;
- and
- a switch which is arranged to connect the third electrode to one of the plurality of constant current sources,
- wherein the third electrode is electrically connected to the first electrode through a power source line.
An electronic device having a light emitting portion, the light emitting portion comprising:
- a first light emitting element formed over a substrate, the first light emitting element comprising a first electrode and a second electrode with a first light emitting material interposed therebetween;
- a second light emitting element comprising a third electrode and a fourth electrode with the first light emitting material interposed therebetween;
- a plurality of constant current sources;
- and
- a switch which is arranged to connect the third electrode to one of the plurality of constant current sources,
- wherein the third electrode is electrically connected to the first electrode through a buffer amplifier and a power source line.
Dependencies are inferred from the claim text.