Display device

Inventors: Shunpei Yamazaki (Tokyo, JP); Hajime Kimura (Kanagawa, JP); Atsushi Umezaki (Kanagawa, JP); Yasunori Yoshida (Kanagawa, JP); Hideaki Shishido (Kanagawa, JP); Takuya Kimishima (Kanagawa, JP); Yasuyuki Arai (Kanagawa, JP)

Assignee: Semiconductor Energy Laboratory Co., Ltd.

G09G3/3233 G09G3/006 G09G3/20 G09G3/2022 G09G3/3225 G09G2300/0809 G09G2300/0819 G09G2300/0842 G09G2310/0272 G09G2310/0275 G09G2320/0233 G09G2320/0295 G09G2320/046 G09G2320/048 G09G2330/022 G09G2340/145

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Quick Facts

Patent No.: US 9,824,631
App. No.: 14/819,594
Granted: Nov 21, 2017
Kind: B2

External Links

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Abstract

In a display element such as an organic EL element, deterioration progresses due to light emission, and emission luminance is lowered even if the same voltage is applied to the display element. Therefore, use over time causes variations in luminance of each pixel, thereby a so-called “image burn-in” phenomenon occurs. Given this factor, the invention provides a display device which can reduce the difference in deterioration of a display element in each pixel and suppress variations in light emission of a display element in a pixel. It is prevented that only a specific pixel has a long accumulated lighting time. For that purpose, a gray scale of a display pattern is changed to prevent the difference in deterioration of display element in pixels from increasing. Alternatively, a specific display pattern is prevented from being fixedly displayed in a specific region. Further alternatively, a pixel lagging behind in deterioration is deteriorated so that the accumulated lighting time of pixels is equal to each other.

Claims (42)

1. A display device comprising:

a first and a second wires; and

a pixel comprising:

a first transistor;

a first to a third switches;

a display element; and

a current source circuit,

wherein the first wire is electrically connected to a gate terminal of the first transistor via the first switch,

wherein the second wire is electrically connected to the display element via the second switch and the first transistor, the second switch and the first transistor being connected in series between the second wire and the display element,

wherein the second wire is electrically connected to the first transistor via the third switch and the current source circuit, the third switch and the current source circuit being connected in series between the second wire and the first transistor and in parallel with the second switch.

2. The display device according to claim 1 ,

wherein the current source circuit is programmable.

3. The display device according to claim 1 , further comprising:

a third wire; and

comprised in the current source circuit:

a second transistor;

a fourth and a fifth switch; and

a capacitor,

wherein the second wire is electrically connected to the third switch via the second transistor,

wherein the second wire is electrically connected to a gate terminal of the second transistor via the fourth switch,

wherein the capacitor is electrically connected between the gate terminal and a node between the second transistor and the third switch,

wherein the third wire is electrically connected to the node via the fifth switch.

4. The display device according to claim 1 ,

wherein the display device is configured to set on the second switch and to set off the third switch during an image display operation, and

wherein the display device is configured to set off the second switch and to set on the third switch during a display element aging operation.

5. The display device according to claim 4 ,

wherein the display device is configured to carry out the display element aging operation while charging.

6. The display device according to claim 1 ,