Display apparatus capable of gradational display

• US 6,072,555 A
• Filed: 01/28/1997
• Issued: 06/06/2000
• Est. Priority Date: 02/01/1996
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Iba, Jun, Mizutome, Atsushi, Katakura, Kazunori
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): NGUYEN, DUNG T
• Application Number:
  US08/789,869
• Time in Patent Office: 1,225 Days
• Field of Search: 349/37, 349/85, 349/108, 349/109, 349/143, 349/144, 349/148
• US Class Current: 349/144
• CPC Class Codes: G02F 1/134336 Matrix
• CPC Class Codes: G02F 1/134345 Subdivided pixels, e.g. for grey scale or redundancy

Abstract

A display apparatus is constituted to have a multiplicity of pixels each divided into at least two sub-pixels having mutually different areas including a larger sub-pixel having a larger area and a smaller sub-pixel having a smaller area. Each sub-pixel is provided with a transparent electrode and a low-resistivity conductor connected to the transparent electrode, and the low-resistivity conductor for the larger sub-pixel is set to have a lower resistance than the low-resistivity conductor for the smaller sub-pixel. As a result, a pixel switching characteristic can be uniformized over an entire picture area of the display apparatus regardless of different areas (loads) of the sub-pixels and without using different performances of drivers.

Claims

1. A display apparatus comprising a multiplicity of pixels each divided into at least two sub-pixels having mutually different areas including a larger sub-pixel having a larger area and a smaller sub-pixel having a smaller area, wherein each sub-pixel is provided with a transparent electrode and a low-resistivity conductor connected to the transparent electrode, and the low-resistivity conductor for the larger sub-pixel has a lower resistance than the low-resistivity conductor for the smaller sub-pixel to provide an identical driven waveform delay characteristic.

2. A display apparatus according to claim 1, wherein the resistances of the low-resistivity conductors for the larger and smaller sub-pixels have a ratio therebetween which is inversely proportional to a ratio between the areas of the larger and smaller sub-pixels.

3. A display apparatus according to claim 1, wherein each pixel is designed to have a display state depending on an orientation state of a chiral nematic liquid crystal or a chiral smectic liquid crystal disposed thereat.

4. A display apparatus according to claim 1, wherein the low-resistivity conductor comprises a metal having a resistivity lower than that of the transparent electrode.

5. A display apparatus according to claim 1, wherein the low-resistivity conductors have widths which vary depending on the areas of the sub-pixels associated therewith.

6. A display apparatus according to claim 5, wherein the low-resistivity conductors for all the sub-pixels have an identical thickness.

7. A display apparatus according to claim 1, wherein each pixel is divided into at least three sub-pixels having mutually different areas including a largest sub-pixel having a largest area, a medium sub-pixel, having a medium area and a smallest sub-pixel having a smallest area, and the respective sub-pixels are provided with low-resistivity conductors having different resistances such that the low-resistivity conductor for the largest sub-pixel has a lowest resistance and low-resistivity conductor for the smallest sub-pixel has a highest resistance.

8. A display apparatus according to claim 7, wherein the low-resistivity conductors for the respective sub-pixels have resistances which are inversely proportional to the areas of the sub-pixels.

9. A display apparatus according to claim 7, wherein each pixel is designed to have a display state depending on an orientation state of a chiral nematic liquid crystal or a chiral smectic liquid crystal disposed thereat.

10. A display apparatus according to claim 7, wherein the low-resistivity conductor comprises a metal having a resistivity lower than that of the transparent electrode.

11. A display apparatus according to claim 7, wherein the low-resistivity conductors have widths which vary depending on the areas of the sub-pixels associated therewith.

12. A display apparatus according to claim 1 or 7, wherein low-resistivity conductors having mutually different resistances are disposed alternately in a horizontal scanning direction or in a vertical scanning direction.

13. A display apparatus according to claim 1 or 7, wherein low-resistivity conductors having mutually different resistances are disposed alternately in a horizontal scanning direction and in a vertical scanning direction.

14. A display apparatus according to claim 1 or 7, wherein first and second sub-pixels having mutually different areas are connected to a first low-resistivity conductor having a prescribed resistance, and third and fourth sub-pixels having mutually different sub-pixels are connected to a second low-resistivity conductor having a resistance higher than the prescribed resistance.

15. A display apparatus according to claim 14, wherein the first and second sub-pixels are disposed on a common scanning line, and the third and fourth sub-pixels are disposed on another common scanning line.

16. A display apparatus according to claim 1 or 7, wherein a sub-pixel connected to a first low-resistivity conductor having a prescribed resistance has an area which is 1.5 to 2.5 times that of a sub-pixel connected to a second low-resistivity conductor having a resistance higher than the prescribed resistance.

17. A display apparatus according to claim 16, wherein at least two sub-pixels having mutually different areas are connected to the first low-resistivity conductor.

18. A display apparatus according to claim 16, wherein at least two sub-pixels having mutually different areas are connected to the second low-resistivity conductor.

19. A display apparatus according to claim 16, wherein at least three sub-pixels having mutually different areas are disposed in succession and connected in parallel to the first or second low-resistivity conductor so that one having a smallest area among the three sub-pixels is disposed between the remaining two sub-pixels.

20. A display apparatus according to claim 1 or 7, wherein said sub-pixels are in a plurality of mutually different colors.

21. A display apparatus according to claim 1 or 7, wherein the display apparatus is a color display apparatus including a multiplicity of color pixels in plural colors, and each color pixel is divided into said at least two or three sub-pixels.

22. A display apparatus according to claim 21, wherein said color display apparatus includes a multiplicity of color pixels in three colors of first to three colors,

the first and second low-resistivity conductors having mutually different resistances are arranged alternately in a horizontal scanning direction, and

the sub-pixels in the first to third colors are arranged repetitively in the horizontal scanning direction.

23. A display apparatus according to claim 22, wherein said first to three colors are red, green and blue.

24. A display apparatus according to claim 1 or 7, further including a light source.

25. A display apparatus according to claim 1 or 7, further including a signal source for generating picture signals supplied to the display apparatus.

26. A display apparatus, comprising a group of scanning electrodes and a group of data electrodes intersecting the scanning electrodes so as to form a sub-pixel at each intersection of the scanning electrodes and the data electrodes so that a plurality of the sub-pixels constitute a pixel in combination and the display apparatus is provided with a multiplicity of such pixels, wherein

at least one of the group of scanning electrodes and the group of data electrodes includes a first-type electrode comprising a combination of a first transparent conductor film having a first area and a first low-resistivity conductor connected to the first transparent conductor film, and a second-type electrode comprising a combination of a second transparent conductor film having a second area smaller than the first area and a second low-resistivity conductor connected to the second transparent conductor film, and

the first low-resistivity conductor has a lower resistance than the second low-resistivity conductor to provide an identical driven waveform delay characteristic.

27. A display apparatus according to claim 26, wherein each of the first and second transparent conductor films is in a form of roughly a stripe but divided into a plurality of discrete segments.

28. A display apparatus according to claim 26, wherein at least one of the first and second transparent conductor films is in the form of a continuous stripe.

29. A display apparatus according to claim 26, wherein said first and second low-resistivity conductors are composed of an identical material having a lower resistivity than that of the transparent conductor films.

30. A display apparatus according to claim 29, wherein said first and second low-resistivity conductors have an identical thickness.

31. A display apparatus according to claim 26, wherein said first transparent conductor film is a transparent electrode providing at least two sub-pixels having mutually different areas, and said second transparent conductor film is a transparent electrode providing a sub-pixel having a different area from those of said at least two sub-pixels.

32. A display apparatus according to claim 26, wherein said first and second low-resistivity conductors are disposed alternately in a horizontal scanning direction or in a vertical scanning direction.

33. A display apparatus according to claim 26, wherein said first and second low-resistivity conductors are disposed alternately in a vertical scanning direction.

34. A display apparatus according to claim 26, wherein first and second sub-pixels having mutually different areas are connected to said first low-resistivity conductor third and fourth sub-pixels having mutually different sub-pixels are connected to said second low-resistivity conductor, the first and second sub-pixels are disposed on a common scanning line, and the third and fourth sub-pixels are disposed on another common scanning line.

35. A display apparatus according to claim 26, wherein a sub-pixel connected to said first low-resistivity conductor has an area which is larger than that of a sub-pixel connected to said second low-resistivity conductor disposed on an electrode common to said sub-pixel.

36. A display apparatus according to claim 26, wherein at least three sub-pixels having mutually different areas are disposed in succession on an electrode connected to the first or second low-resistivity conductor so that one having a smallest area among the three sub-pixels is disposed between the remaining two sub-pixels.

37. A display apparatus according to claim 26, wherein said sub-pixels are in a plurality of mutually different colors.

38. A display apparatus according to claim 26, wherein the display apparatus is a color display apparatus including a multiplicity of color pixels in plural colors, and each color pixel is divided into said at least two or three sub-pixels.

39. A display apparatus according to claim 38, wherein said color display apparatus includes a multiplicity of color pixels in three colors of first to three colors,

the first and second low-resistivity conductors having mutually different resistances are arranged alternately in a horizontal scanning direction, and

the sub-pixels in the first to third colors are arranged repetitively in the horizontal scanning direction.

40. A display apparatus according to claim 39, wherein said first to three colors are red, green and blue.

41. A display apparatus according to claim 26, further including a light source.

42. A display apparatus according to claim 26, further including a signal source for generating picture signals supplied to the display apparatus.

43. A display apparatus according to claim 26, wherein the display apparatus is a color display apparatus including a multiplicity of color pixels in three colors, each color pixel is divided into a plurality of sub-pixels, and sub-pixels of three colors are equally provided with the first and second low-resistivity conductors.

44. A display apparatus according to claim 26, wherein the resistances of the first and second low-resistivity conductors have a ratio therebetween which is inversely proportional to a ratio between the areas of the first and second transparent conductor films.

45. A display apparatus according to claim 26, wherein each pixel is designed to have a display state depending on an orientation state of a chiral nematic liquid crystal or a chiral smectic liquid crystal disposed thereat.