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US 2013/0075709 A1Published application
Light Emitting Device and Electronic Equipment
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorJun Koyama
Life of this patent
Estimating the term…
Abstract
A display device capable of keeping the luminance constant irrespective of temperature change is provided as well as a method of driving the display device. A current mirror circuit composed of transistors is placed in each pixel. A first transistor and a second transistor of the current mirror circuit are connected such that the drain current of the first transistor is kept in proportion to the drain current of the second transistor irrespective of the load resistance value. The drain current of the first transistor is controlled by a driving circuit in accordance with a video signal and the drain current of the second transistor is caused to flow into an OLED, thereby controlling the OLED drive current and the luminance of the OLED.
Claims27
A display panel comprising:
- a light emitting element over a substrate;
- a capacitor over the substrate;
- a first transistor over the substrate;
- a second transistor over the substrate;
- a third transistor over the substrate;
- a fourth transistor over the substrate;
- a wiring over the substrate;
- and
- a seal member over the substrate,
- wherein one of a source and a drain of the first transistor is electrically connected to the light emitting element,
- wherein the other of the source and the drain of the first transistor is directly connected to one of a source and a drain of the second transistor,
- wherein the other of the source and the drain of the second transistor is directly connected to a first line,
- wherein one of a source and a drain of the third transistor is directly connected to a gate of the first transistor,
- wherein the other of the source and the drain of the third transistor is electrically connected to a second line,
- wherein a gate of the third transistor is directly connected to a third line,
- wherein one of a source and a drain of the fourth transistor is directly connected to the other of the source and the drain of the first transistor,
- wherein a gate of the fourth transistor is directly connected to a fourth line,
- wherein a first electrode of the capacitor is directly connected to the gate of the first transistor,
- wherein a second electrode of the capacitor is directly connected to the first line,
- wherein the wiring is electrically connected to the first line,
- wherein the wiring is in contact with the seal member, and
- wherein. the wiring is electrically connectable to an FPC.
19 more elements
A display panel comprising:
- a light emitting element over a substrate;
- a capacitor over the substrate;
- a first transistor over the substrate;
- a second transistor over the substrate;
- and
- a third transistor over the substrate,
- wherein one of a source and a drain of the first transistor is electrically connected to the light emitting element,
- wherein the other of the source and the drain of the first transistor is directly connected to one of a source and a drain of the second transistor,
- wherein the other of the source and the drain of the second transistor is directly connected to a first line,
- wherein one of a source and a drain of the third transistor is directly connected to a gate of the first transistor,
- wherein the other of the source and the drain of the third transistor is electrically connected to a second line,
- wherein a gate of the third transistor is directly connected to a third line,
- wherein a first electrode of the capacitor is directly connected to the gate of the first transistor,
- wherein a second electrode of the capacitor is directly connected to the first line, and
- wherein the capacitor and the first line overlap with each other.
12 more elements
A display panel comprising:
- a light emitting element;
- a capacitor;
- a first transistor;
- a second transistor;
- a third transistor;
- and
- a fourth transistor,
- wherein one of a source and a drain of the first transistor is electrically connected to the light emitting element,
- wherein the other of the source and the drain of the first transistor is directly connected to one of a source and a drain of the second transistor,
- wherein the other of the source and the drain of the second transistor is directly connected to a first line,
- wherein one of a source and a drain of the third transistor is directly connected to a gate of the first transistor,
- wherein the other of the source and the drain of the third transistor is electrically connected to a second line,
- wherein a gate of the third transistor is directly connected to a third line,
- wherein one of a source and a drain of the fourth transistor is directly connected to the other of the source and the drain of the first transistor,
- wherein a gate of the fourth transistor is directly connected to a fourth line,
- wherein a first electrode of the capacitor is directly connected to the gate of the first transistor,
- wherein a second electrode of the capacitor is directly connected to the first line, and
- wherein the second line is supplied with a voltage.
15 more elements
Dependencies are inferred from the claim text.