Display apparatus

• US 6,714,212 B1
• Filed: 11/19/1997
• Issued: 03/30/2004
• Est. Priority Date: 10/05/1993
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tsuboyama, Akira, Suga, Kazumi, Katakura, Kazunori, Makita, Takeshi, Iwasaki, Manabu
• Primary Examiner(s): CHANG, KENT WU
• Application Number:
  US08/974,551
• Time in Patent Office: 2,323 Days
• Field of Search: 345/87, 345/694, 345/695, 345/696, 345/88, 345/89
• US Class Current: 345/696
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• CPC Class Codes: G09G 3/2059 using error diffusion
• CPC Class Codes: G09G 3/2074 using sub-pixels

Abstract

A display apparatus has a plurality unit pixels each divided into a least three sub-pixels for displaying a halftone. The at least three sub-pixels have mutually different areas, so that one sub-pixel among the at least three sub-pixels has a maximum area which does not exceed a total area of the remaining sub-pixels. As a result, it is possible to obviate a so-called linear defect occurring in a multi-level gradational display by suppressing the shift of gravity center of light spots and change in sub-pixel arrangement pattern in displaying slightly different gradation levels.

Claims

1. A display apparatus comprising:

display means including a display panel having a plurality of unit pixels each divided into at least three sub-pixels for displaying a halftone, said at least three sub-pixels having mutually different areas, wherein one sub-pixel with the largest area among said at least three sub-pixels has a maximum area which does not exceed a total area of the remaining sub-pixels among said at least three sub-pixels; and

an image processing circuit for displaying a number of halftone levels on said display panel by said plurality of unit pixels, with the number being larger than a number of halftone levels that can be displayed by a single unit pixel, wherein

each said unit pixel is divided into three longitudinally elongated color pixels which are disposed laterally adjacently, and

each color pixel is divided only in a longitudinal direction into said at least three sub-pixels having areal ratios such that at least one halftone level can be displayed by selecting one from at least two display patterns each formed by a combination of on-state and off-state of the sub-pixels.

2. An apparatus according to claim 1, including a plurality of pixels each divided into a plurality of color pixels for color display comprising said unit pixels, each of which is divided into said at least three sub-pixels.

3. An apparatus according to claim 1, wherein the maximum area of the one sub-pixel is smaller than the total area of the remaining sub-pixels.

4. A display apparatus according to claim 1, wherein said unit pixel is divided into three sub-pixels having an areal ratio of 1:

2;

3.

5. A display apparatus according to claim 1, wherein one unit pixel is divided into four sub-pixels having areal ratios selected from 1:

2;

3;

6, 1;

2;

4;

7, 1;

2;

3;

5, 1;

2;

3;

4, 1;

2;

4;

5, 1;

2;

4;

6, 2;

3;

4;

5 or 2;

3;

4;

6.

6. A display apparatus according to claim 1, wherein said at least three pixels include a smallest sub-pixel and a second smallest sub-pixel having an areal ratio of 1:

2.

7. A display apparatus comprising:

display means including a display panel having a plurality of unit pixels each divided into at least three sub-pixels for displaying a halftone, said at least three sub-pixels having mutually different areas, wherein one sub-pixel with the largest area among said at least three sub-pixels has a maximum area which does not exceed a total area of the remaining sub-pixels among said at least three sub-pixels; and

an image processing circuit for converting data into binary data according to a dither method, wherein

each said unit pixel is divided into three longitudinally elongated color pixels which are disposed laterally adjacently, and

each color pixel is divided only in a longitudinal direction into said at least three sub-pixels having areal ratios such that at least one halftone level can be displayed by selecting one from at least two display patterns each formed by a combination of on-state and off-state of said sub-pixels.

8. An apparatus according to claim 7, including a plurality of pixels each divided into a plurality of color pixels for color display comprising said unit pixels, each of which is divided into said at least three sub-pixels.

9. An apparatus according to claim 7, wherein the maximum area of the one sub-pixel is smaller than the total area of the remaining sub-pixels.

10. A display apparatus according to claim 7, wherein said unit pixel is divided into three sub-pixels having an areal ratio of 1:

2;

3.

11. A display apparatus according to claim 7, wherein one unit pixel is divided into four sub-pixels having areal ratios selected from 1:

2;

3;

6, 1;

2;

4;

7, 1;

2;

3;

5, 1;

2;

3;

4, 1;

2;

4;

5, 1;

2;

4;

6, 2;

3;

4;

5 or 2;

3;

4;

6.

12. A display apparatus according to claim 7, wherein said at least three pixels include a smallest sub-pixel and a second smallest sub-pixel having an areal ratio of 1:

2.

13. A display apparatus comprising:

display means including a display panel having a plurality of unit pixels each divided into at least three sub-pixels for displaying a halftone, said at least three sub-pixels having mutually different areas, wherein one sub-pixel with the largest area among said at least three sub-pixels has a maximum area which does not exceed a total area of the remaining sub-pixels among said at least three sub-pixels; and

an image processing circuit for converting data into binary data by an error-diffusion method, wherein

each said unit pixel is divided into three longitudinally elongated color pixels which are disposed laterally adjacently, and

each color pixel is divided only in a longitudinal direction into said at least three sub-pixels having areal ratios such that at least one halftone level can be displayed by selecting one from at least two display patterns each formed by a combination of on-state and off-state of the sub-pixels.

14. An apparatus according to claim 13, including a plurality of pixels each divided into a plurality of color pixels for color display comprising said unit pixels, each of which is divided into said at least three sub-pixels.

15. An apparatus according to claim 13, wherein the maximum area of the one sub-pixel is smaller than the total area of the remaining sub-pixels.

16. A display apparatus according to claim 13, wherein said unit pixel is divided into three sub-pixels having an areal ratio of 1:

2;

3.

17. A display apparatus according to claim 13, wherein one unit pixel is divided into four sub-pixels having areal ratios selected from 1:

2;

3;

6, 1;

2;

4;

7, 1;

2;

3;

5, 1;

2;

3;

4, 1;

2;

4;

5, 1;

2;

4;

6, 2;

3;

4;

5 or 2;

3;

4;

6.

18. A display apparatus according to claim 13, wherein said at least three pixels include a smallest sub-pixel and a second smallest sub-pixel having an areal ratio of 1:

2.

19. A display apparatus comprising:

display means including a display panel having a plurality of unit pixels each divided into at least three sub-pixels for displaying a halftone, said at least three sub-pixels having mutually different areas, wherein one sub-pixel with the largest area among said at least three sub-pixels has a maximum area which does not exceed a total area of the remaining sub-pixels among said at least three sub-pixels; and

an image processing circuit for converting data into binary data by a density pattern method, wherein

each said unit pixel is divided into three longitudinally elongated color pixels which are disposed laterally adjacently, and

each color pixel is divided only in a longitudinal direction into said at least three sub-pixels having areal ratios such that at least one halftone level can be displayed by selecting one from at least two display patterns each formed by a combination of on-state and off-state of the sub-pixels.

20. An apparatus according to claim 19, including a plurality of pixels each divided into a plurality of color pixels for color display comprising said unit pixels, each of which is divided into said at least three sub-pixels.

21. An apparatus according to claim 19, wherein the maximum area of the one sub-pixel is smaller than the total area of the remaining sub-pixels.

22. A display apparatus according to claim 19, wherein said unit pixel is divided into three sub-pixels having an areal ratio of 1:

2;

3.

23. A display apparatus according to claim 19, wherein one unit pixel is divided into four sub-pixels having areal ratios selected from 1:

2;

3;

6, 1;

2;

4;

7, 1;

2;

3;

5, 1;

2;

3;

4, 1;

2;

4;

5, 1;

2;

4;

6, 2;

3;

4;

5 or 2;

3;

4;

6.

24. A display apparatus according to claim 19, wherein said at least three pixels include a smallest sub-pixel and a second smallest sub-pixel having an areal ratio of 1:

2.

25. A display apparatus, comprising:

display means including a display panel having a plurality of pixels each divided into a plurality of color pixels for color display, including color pixels of at least one color each divided into at least three sub-pixels, said at least three sub-pixels having mutually different areas, wherein one sub-pixel with the largest area among said at least three sub-pixels has a maximum area which is smaller than a total area of the remaining sub-pixels; and

an image processing circuit for displaying a number of halftone levels by plural color pixels, the number being larger than a number of halftone levels that can be displayed by a single color pixel, wherein

each said unit pixel is divided into three longitudinally elongated color pixels which are disposed laterally adjacently, and

each color pixel is divided only in a longitudinal direction into said at least three sub-pixels having areal ratios such that at least one halftone level can be displayed by selecting one from at least two display patterns each formed by a combination of on-state and off-state of the sub-pixels.

26. An apparatus according to claim 25, further including an image processing circuit for converting data into binary data according to a dither method.

27. An apparatus according to claim 25, further including an image processing circuit for converting data into binary data by an error-diffusion method.

28. An apparatus according to claim 25, further including an image processing circuit for converting data into binary data by a density pattern method.