DISPLAY DEVICE

• US 20070109284A1
• Filed: 08/07/2006
• Published: 05/17/2007
• Est. Priority Date: 08/12/2005
• Status: Abandoned Application

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Umezaki, Atsushi, Kimura, Hajime, Yamazaki, Shunpei, Arai, Yasuyuki, Yoshida, Yasunori, Shishido, Hideaki, Kimishima, Takuya
• Application Number:
  US11/462,829
• Publication Number:
  US 20070109284A1
• Time in Patent Office: Days
• US Class Current: 345/204
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2310/0272 Details of drivers for data electrodes, the drivers communicating data to the pixels by means of a current
• CPC Class Codes: G09G 2310/0275 Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/046 Dealing with screen burn-in prevention or compensation of the effects thereof
• CPC Class Codes: G09G 2320/048 using evaluation of the usage time
• CPC Class Codes: G09G 2330/022 in absence of operation, e.g. no data being entered during a predetermined time
• CPC Class Codes: G09G 2340/145 related to small screens
• CPC Class Codes: G09G 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: G09G 3/007 Use of pixel shift techniques, e.g. by mechanical shift of the physical pixels or by optical shift of the perceived pixels
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/3225 using an active matrix
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

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

1. A display device comprising:

a battery; and

a circuit for switching between a first display mode and a second display mode depending on a power of the battery,

wherein a contrasting of a display image is inverted in the first display mode and the second display mode.

2. A display device comprising:

a battery; and

a circuit for switching between a first display collar and a second display collar in which text is displayed depending on a power of the battery.

3. A display device comprising:

a circuit for switching between a first display mode where text is displayed in black and a second display mode where text is displayed in white and an outline thereof is displayed in black.

4. The display device according to claim 3, wherein the circuit switches between the modes per day.

5. The display device according to claim 3, wherein the circuit switches between the modes per hour.

6. The display device according to claim 3, wherein the circuit switches between the modes when the display device remains unoperated for a certain period.

7. The display device according to claim 3, wherein the circuit switches between the modes each time a power source is turned on.

8. The display device according to claim 3, wherein the circuit switches between the modes depending on whether an e-mail is received or sent.

9. A display device comprising:

a circuit for switching between a first display mode where text is displayed in white and a second display mode where text is displayed in black and an outline thereof is displayed in white.

10. The display device according to claim 9, wherein the circuit switches between the modes per day.

11. The display device according to claim 9, wherein the circuit switches between the modes per hour.

12. The display device according to claim 9, wherein the circuit switches between the modes when the display device remains unoperated for a certain period.

13. The display device according to claim 9, wherein the circuit switches between the modes each time a power source is turned on.

14. The display device according to claim 9, wherein the circuit switches between the modes depending on whether an e-mail is received or sent.

15. A display device comprising:

a circuit which changes the display image by shifting a display position of a display text,

wherein block of pixels which is needed for displaying a character is arranged in a rectangular pattern, and

whrein when the block of pixels has a horizontal length a and a vertical length b, the circuit shifts a display position of the display text to a horizontal direction by x (−

a≦

x≦

a) and to a vertical direction by y (−

b≦

y≦

b).

16. The display device according to claim 15, wherein the circuit shifts text per day.

17. The display device according to claim 15, wherein the circuit shifts text per hour.

18. The display device according to claim 15, wherein the circuit shifts text when the display device remains unoperated for a certain period.

19. The display device according to claim 15, wherein the circuit shifts text each time a power source is turned on.

20. The display device according to claim 15, wherein the circuit shifts text each time text is inputted.

21. The display device according to claim 15, wherein the circuit shifts text each time text of one row is inputted.

22. A display device comprising:

a counter for counting an accumulated displaying time of an icon and an average accumulated lighting time of pixels in a region where an icon is not displayed;

a memory circuit portion in which data counted by the counter is stored; and

a correcting circuit for correcting an image signal with the use of the data stored in the memory circuit portion so that luminance of pixels in the icon and average luminance of pixels in the region where an icon is not displayed are equal to each other.