DISPLAY DEVICE

• US 20060244702A1
• Filed: 05/01/2006
• Published: 11/02/2006
• Est. Priority Date: 05/02/2005
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: KOYAMA, Jun, YANAI, Hiromi, OSAME, Mitsuaki, YAMAZAKI, Shunpei, TANADA, Yoshifumi, FUKUMOTO, Ryota
• Granted Patent: US 7,724,247 B2
• Time in Patent Office: Days
• US Class Current: 345/89
• CPC Class Codes: G06F 3/1431 using a single graphics controller
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/0613 The adjustment depending on the type of the information to be displayed
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2320/10 Special adaptations of display systems for operation with variable images
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2340/0428 Gradation resolution change
• CPC Class Codes: G09G 2340/0492 Change of orientation of the displayed image, e.g. upside-down, mirrored
• CPC Class Codes: G09G 2340/14 Solving problems related to the presentation of information to be displayed
• CPC Class Codes: G09G 2360/144 the light being ambient light
• 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 5/399 using two or more bit-mapped memories, the operations of which are switched in time, e.g. ping-pong buffers
• CPC Class Codes: H04M 1/0214 Foldable telephones, i.e. with body parts pivoting to an open position around an axis parallel to the plane they define in closed position combined with translation movement H04M1/0235
• CPC Class Codes: H04M 1/0266 for a display module assembly
• CPC Class Codes: H04M 1/22 Illumination; Arrangements for improving the visibility of characters on dials
• CPC Class Codes: H04M 2250/16 including more than one display unit
• CPC Class Codes: H10K 59/13 comprising photosensors that control luminance
• CPC Class Codes: H10K 59/1315 : comprising structures specially adapted for lowering the resistance

Abstract

The object of the invention is to provide a display device of which the display is visible in a dark place or under strong external light. The present invention is a display device which performs display, changing the grayscale number corresponding to the external light strength, and a display device which can switch the display mode corresponding to contents displayed on the screen. The display contents include a text display mode displaying mainly characters and symbols, a picture display mode displaying images with a small number of colors such as a comic, a video mode displaying natural images with a large number of colors such as a photograph and a moving image, and the like. By switching the grayscale number arbitrarily according to these display modes, visibility can be ensured in a wide range from a dark place or under an indoor fluorescent light to under outdoor sunlight. For example, the grayscale number is switched so that display of from 2 to 8 grayscales is performed in the text display mode, display of from 4 to 16 grayscales is performed in the picture display mode, and display of from 64 to 1024 grayscales is performed in the video mode.

Claims

1. A display device comprising:

a display part;

a controller for receiving a original video signal; and

a light sensor for receiving external light, and for outputting a selecting signal according to a strength of the external light,

wherein the controller includes;

a grayscale converting part for changing grayscale number of the original video signal, and for outputting a changed video signal; and

a grayscale output selecting part for selectively supplying the changed video signal to the display part, according to the selecting signal.

2. The driving method of the display device, according to claim 1,

the display device displays character information and a still image with a lower grayscale when the external light strength is no less than 100,000 lux, than that of when an external light strength is fewer than 500 lux and no less than 400 lux.

3. The driving method of the display device, according to claim 1,

wherein grayscale number of the video signal is any one of 2 to 8 when the external light strength is fewer than 100,000 lux and no less than 323,000 lux, and

wherein grayscale number of the video signal is any one of 4 to 16 when the external light strength is fewer than 2,000 lux and no less than 1,000 lux.

4. A display device comprising:

a display part;

a controller for receiving a original video signal; and

a light sensor for receiving external light, and for outputting a selecting signal according to a strength of the external light,

wherein the controller includes;

a grayscale converting part for changing grayscale number of the original video signal, and for outputting a changed video signal; and

a grayscale output selecting part for selectively supplying the changed video signal to the display part, according to the selecting signal,

wherein grayscale number of the changed video signal is i when the strength of the external light is x lux,

wherein grayscale number of the changed video signal is j when the strength of the external light is y lux,

wherein grayscale number of the changed video signal is k when the strength of the external light is z lux,

wherein i, j and k are natural numbers which fulfill a formula i>

j>

k, and

wherein x, y, and z are positive real numbers which fulfill a formula x<

y<

z.

5. The driving method of the display device, according to claim 4,

the display device displays character information and a still image with a lower grayscale when the external light strength is no less than 100,000 lux, than that of when an external light strength is fewer than 500 lux and no less than 400 lux.

6. The driving method of the display device, according to claim 4,

wherein grayscale number of the video signal is any one of 2 to 8 when the external light strength is fewer than 100,000 lux and no less than 323,000 lux, and

wherein grayscale number of the video signal is any one of 4 to 16 when the external light strength is fewer than 2,000 lux and no less than 1,000 lux.

7. A display device comprising:

a display part;

a controller for receiving a original video signal;

a memory part; and

a light sensor for receiving external light, and for outputting a selecting signal according to a strength of the external light,

wherein the controller includes;

a grayscale converting part for changing grayscale number of the original video signal, and for outputting a changed video signal to the memory part; and

a grayscale output selecting part for selectively supplying the changed video signal stored in the memory part to the display part, according to the selecting signal.

8. The driving method of the display device, according to claim 7,

the display device displays character information and a still image with a lower grayscale when the external light strength is no less than 100,000 lux, than that of when an external light strength is fewer than 500 lux and no less than 400 lux.

9. The driving method of the display device, according to claim 7,

wherein grayscale number of the video signal is any one of 2 to 8 when the external light strength is fewer than 100,000 lux and no less than 323,000 lux, and

wherein grayscale number of the video signal is any one of 4 to 16 when the external light strength is fewer than 2,000 lux and no less than 1,000 lux.

10. A display device comprising:

a display part;

a controller for receiving a original video signal;

a memory part; and

a light sensor for receiving external light, and for outputting a selecting signal according to a strength of the external light,

wherein the controller includes;

a grayscale converting part for changing grayscale number of the original video signal, and for outputting a changed video signal to the memory part; and

a grayscale output selecting part for selectively supplying the changed video signal stored in the memory part to the display part, according to the selecting signal,

wherein grayscale number of the changed video signal is i when the strength of the external light is x lux,

wherein grayscale number of the changed video signal is j when the strength of the external light is y lux,

wherein grayscale number of the changed video signal is k when the strength of the external light is z lux,

wherein i, j and k are natural numbers which fulfill a formula i>

j>

k, and

wherein x, y, and z are positive real numbers which fulfill a formula x<

y<

z.

11. The driving method of the display device, according to claim 10,

the display device displays character information and a still image with a lower grayscale when the external light strength is no less than 100,000 lux, than that of when an external light strength is fewer than 500 lux and no less than 400 lux.

12. The driving method of the display device, according to claim 10,

wherein grayscale number of the video signal is any one of 2 to 8 when the external light strength is fewer than 100,000 lux and no less than 323,000 lux, and

wherein grayscale number of the video signal is any one of 4 to 16 when the external light strength is fewer than 2,000 lux and no less than 1,000 lux.

13. A driving method of a display device comprising the steps of:

receiving external light in a light sensor;

supplying a selecting signal to a controller, according to a strength of the external light received in the light sensor; and

supplying a video signal selectively from the controller to a display part, according to the selecting signal,

wherein grayscale number of the changed video signal is i when the strength of the external light is x lux,

wherein grayscale number of the changed video signal is j when the strength of the external light is y lux,

wherein grayscale number of the changed video signal is k when the strength of the external light is z lux,

wherein i, j and k are natural numbers which fulfill a formula i>

j>

k, and

wherein x, y, and z are positive real numbers which fulfill a formula x<

y<

z.

14. The driving method of the display device, according to claim 13,

the display device displays character information and a still image with a lower grayscale when the external light strength is no less than 100,000 lux, than that of when an external light strength is fewer than 500 lux and no less than 400 lux.

15. The driving method of the display device, according to claim 13,

wherein grayscale number of the video signal is any one of 2 to 8 when the external light strength is fewer than 100,000 lux and no less than 323,000 lux, and

wherein grayscale number of the video signal is any one of 4 to 16 when the external light strength is fewer than 2,000 lux and no less than 1,000 lux.

16. A driving method of a display device comprising the steps of:

receiving external light in a light sensor;

supplying a selecting signal to a controller, according to a strength of the external light received in the light sensor; and

supplying a video signal selectively from the controller to a display part, according to the selecting signal,

wherein grayscale number of the changed video signal is i when the strength of the external light is x lux,

wherein grayscale number of the changed video signal is j when the strength of the external light is y lux,

wherein grayscale number of the changed video signal is k when the strength of the external light is z lux,

wherein i, j and k are natural numbers which fulfill a formula i>

j>

k,

wherein x, y, and z are positive real numbers which fulfill a formula x<

y<

z, and

wherein display modes for text display, still image display and moving image display are switched over according to the strength of the external light.

17. The driving method of the display device, according to claim 16,

the display device displays character information and a still image with a lower grayscale when the external light strength is no less than 100,000 lux, than that of when an external light strength is fewer than 500 lux and no less than 400 lux.

18. The driving method of the display device, according to claim 16,

wherein grayscale number of the video signal is any one of 2 to 8 when the external light strength is fewer than 100,000 lux and no less than 323,000 lux, and

wherein grayscale number of the video signal is any one of 4 to 16 when the external light strength is fewer than 2,000 lux and no less than 1,000 lux.

19. A driving method of a display device comprising the steps of:

receiving external light in a light sensor;

supplying a selecting signal to a controller, according to a strength of the external light received in the light sensor; and

supplying a video signal selectively from the controller to a display part, according to the selecting signal,

wherein display modes for text display, still image display and moving image display are switched over according to the strength of the external light,

wherein grayscale number of the video signal is any one of 2 to 8, in the text display mode,

wherein grayscale number of the video signal is any one of 4 to 16, in the text display mode, and

wherein grayscale number of the video signal is any one of 64 to 1024, in the text display mode.

20. The driving method of the display device, according to claim 19,

the display device displays character information and a still image with a lower grayscale when the external light strength is no less than 100,000 lux, than that of when an external light strength is fewer than 500 lux and no less than 400 lux.

21. The driving method of the display device, according to claim 19,

wherein grayscale number of the video signal is any one of 2 to 8 when the external light strength is fewer than 100,000 lux and no less than 323,000 lux, and

wherein grayscale number of the video signal is any one of 4 to 16 when the external light strength is fewer than 2,000 lux and no less than 1,000 lux.

22. A driving method of a display device comprising the steps of:

receiving external light in a light sensor;

supplying a selecting signal to a controller, according to a strength of the external light received in the light sensor; and

supplying a video signal selectively from the controller to a display part, according to the selecting signal, wherein grayscale number of the video signal is 2, when the external light strength is no less than 100,000 lux,

wherein grayscale number of the video signal is any one of 2 to 8, when the external light strength is fewer than 100,000 lux and no less than 10,000 lux,

wherein grayscale number of the video signal is any one of 4 to 16, when the external light strength is fewer than 10,000 lux and no less than 1,000 lux,

wherein grayscale number of the video signal is any one of 16 to 64, when the external light strength is fewer than 1,000 lux and no less than 100 lux, and

wherein grayscale number of the video signal is any one of 64 to 1024, when the external light strength is fewer than 100 lux.

23. The driving method of the display device, according to claim 22,

the display device displays character information and a still image with a lower grayscale when the external light strength is no less than 100,000 lux, than that of when an external light strength is fewer than 500 lux and no less than 400 lux.

24. The driving method of the display device, according to claim 22,

wherein grayscale number of the video signal is any one of 2 to 8 when the external light strength is fewer than 100,000 lux and no less than 323,000 lux, and wherein grayscale number of the video signal is any one of 4 to 16 when the external light strength is fewer than 2,000 lux and no less than 1,000 lux.