Liquid crystal display

• US 20050122441A1
• Filed: 12/03/2004
• Published: 06/09/2005
• Est. Priority Date: 12/05/2003
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Shimoshikiryoh, Fumikazu
• Granted Patent: US 7,429,981 B2
• Time in Patent Office: Days
• US Class Current: 349/38
• CPC Class Codes: G02F 1/134345 Subdivided pixels, e.g. for grey scale or redundancy
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/13624 having more than one switching element per pixel
• CPC Class Codes: G09G 2300/0443 with several sub-pixels for the same colour in a pixel, not specifically used to display gradations G09G3/364 takes precedence
• CPC Class Codes: G09G 2300/0447 for multi-domain technique to improve the viewing angle in a liquid crystal display, such as multi-vertical alignment [MVA]
• CPC Class Codes: G09G 2300/0876 Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/028 by changing the viewing angle properties, e.g. widening the viewing angle, adapting the viewing angle to the view direction
• CPC Class Codes: G09G 3/2074 using sub-pixels
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors

Abstract

A liquid crystal display of the invention includes a plurality of pixels each of which has a liquid crystal layer and a plurality of electrodes for applying a voltage to the liquid crystal layer and which are arranged in a matrix of rows and columns, wherein: each of the plurality of pixels has a first sub-pixel and a second sub-pixel which can apply mutually different voltages to the liquid crystal layer, where the first sub-pixel has a higher brightness than the second sub-pixel in certain gradations; the first sub-pixel and the second sub-pixel each has: a liquid crystal capacitor formed by a counter electrode and a sub-pixel electrode opposing the counter electrode via the liquid crystal layer, and a storage capacitor formed by a storage capacitor electrode connected electrically to the sub-pixel electrode, an insulating layer, and a storage capacitor counter electrode opposing the storage capacitor electrode via the insulating layer; the counter electrode is a single electrode shared by the first sub-pixel and the second sub-pixel, and the storage capacitor counter electrodes of the first sub-pixel and the second sub-pixel are electrically independent of each other; and the storage capacitor counter electrode of the first sub-pixel in any of the plurality of pixels and the storage capacitor counter electrode of the second sub-pixel of a pixel adjacent to any of the pixels in the column direction are electrically independent of each other.

Claims

1. A liquid crystal display, comprising a plurality of pixels each of which has a liquid crystal layer and a plurality of electrodes for applying a voltage to the liquid crystal layer and which are arranged in a matrix of rows and columns, wherein:

each of the plurality of pixels has a first sub-pixel and a second sub-pixel which can apply mutually different voltages to the liquid crystal layer, where the first sub-pixel has a higher brightness than the second sub-pixel in certain gradations;

the first sub-pixel and the second sub-pixel each comprise;

a liquid crystal capacitor formed by a counter electrode and a sub-pixel electrode opposing the counter electrode via the liquid crystal layer, and

a storage capacitor formed by a storage capacitor electrode connected electrically to the sub-pixel electrode, an insulating layer, and a storage capacitor counter electrode opposing the storage capacitor electrode via the insulating layer;

the counter electrode is a single electrode shared by the first sub-pixel and the second sub-pixel, and the storage capacitor counter electrodes of the first sub-pixel and the second sub-pixel are electrically independent of each other; and

the storage capacitor counter electrode of the first sub-pixel in any of the plurality of pixels and the storage capacitor counter electrode of the second sub-pixel of a pixel adjacent to any of the pixels in the column direction are electrically independent of each other.

2. The liquid crystal display according to claim 1, wherein the first sub-pixel in the any of the pixels is arranged in such a way as to be adjacent to the second sub-pixel of the pixel adjacent to the any of the pixels in the column direction.

3. The liquid crystal display according to claim 1, wherein in each of the plurality of pixels, the first sub-pixel is arranged in such a way as to be adjacent to the second sub-pixel in the column direction.

4. The liquid crystal display according to claim 1, comprising a plurality of storage capacitor trunks electrically independent of each other, wherein each of the storage capacitor trunks is electrically connected to any of the storage capacitor counter electrodes of the first sub-pixel and the second sub-pixel in the plurality of pixels via a storage capacitor line.

5. The liquid crystal display according to claim 4, wherein the number of the storage capacitor trunks electrically independent of each other among the plurality of storage capacitor trunks is L, storage capacitor counter voltage supplied by each of the storage capacitor trunks is oscillating voltage, and the period of oscillation is L times a horizontal scanning period.

6. The liquid crystal display according to claim 4, wherein the plurality of storage capacitor trunks electrically independent of each other are an even number of storage capacitor trunks grouped into pairs of storage capacitor trunks which supply storage capacitor counter voltages whose oscillations are 180 degrees out of phase with each other.

7. The liquid crystal display according to claim 1, wherein the number of storage capacitor trunks electrically independent of each other is larger than 8 times the quotient obtained by dividing one horizontal scanning period by a CR time constant which approximates maximum load impedance of the storage capacitor line.

8. The liquid crystal display according to claim 4, wherein the number of storage capacitor trunks electrically independent of each other is larger than 8 times the quotient obtained by dividing one horizontal scanning period by a CR time constant which approximates maximum load impedance of the storage capacitor line and is an even number.

9. The liquid crystal display according to claim 1, wherein:

the plurality of storage capacitor trunks include a first storage capacitor trunk and a second storage capacitor trunk electrically independent of each other; and

if the storage capacitor line connected to the storage capacitor counter electrode of the first sub-pixel of the pixel located at the intersection of an arbitrary column and a given row n among rows formed by the plurality of pixels is designated as CSBL_A_n if the storage capacitor line connected to the storage capacitor counter electrode of the second sub-pixel is designated as CSBL_B_n, and if k is a natural number (including

     0);

CSBL_A_n+k is connected to the first storage capacitor trunk, and

CSBL_B_n+k is connected to the second storage capacitor trunk.

10. The liquid crystal display according to claim 9, wherein the periods of oscillation of first and second storage capacitor counter voltages supplied, respectively, by the first and second storage capacitor trunks are both twice the horizontal scanning period.

11. The liquid crystal display according to claim 10, wherein the second storage capacitor counter voltage lags the first storage capacitor counter voltage by a phase difference of one horizontal scanning period.

12. The liquid crystal display according to claim 11, comprising

two switching elements provided for the first sub-pixel and the second sub-pixel, respectively,

wherein the two switching elements are turned on and off by scan signal voltages supplied to a common scan line, display signal voltages are supplied to the respective sub-pixel electrodes and storage capacitor electrodes of the first sub-pixel and the second sub-pixel from a common signal line when the two switching elements are on, and voltages of the respective storage capacitor counter electrodes of the first sub-pixel and the second sub-pixel change after the two switching elements are turned off;

and

if Td denotes the time required for the first storage capacitor counter voltage to change for the first time after the two switching elements are turned off, Td is larger than 0 horizontal scanning period and smaller than one horizontal scanning period.

13. The liquid crystal display according to claim 12, wherein the Td is approximately equal to 0.5 times the horizontal scanning period.

14. The liquid crystal display according to claim 1, wherein:

the plurality of storage capacitor trunks include a first storage capacitor trunk, second storage capacitor trunk, third storage capacitor trunk, and fourth storage capacitor trunk electrically independent of each other; and

if the storage capacitor line connected to the storage capacitor counter electrode of the first sub-pixel of the pixel located at the intersection of an arbitrary column and a given row n among rows formed by the plurality of pixels is designated as CSBL_A_n, if the storage capacitor line connected to the storage capacitor counter electrode of the second sub-pixel is designated as CSBL_B_n, and if k is a natural number (including

     0);

CSBL_A_n+4*k and CSBL_B_n+2+4*k are connected to the first storage capacitor trunk,

CSBL_B_n+4*k and CSBL_A_n+2+4*k are connected to the second storage capacitor trunk,

CSBL_A_n+1+4*k and CSBL_B_n+3+4*k are connected to the third storage capacitor trunk, and

CSBL_B_n+1+4*k and CSBL_A_n+3+4*k are connected to the fourth storage capacitor trunk.

15. The liquid crystal display according to claim 14, wherein the periods of oscillation of first to fourth storage capacitor counter voltages supplied, respectively, by the first to fourth storage capacitor trunks are all 4 times the horizontal scanning period.

16. The liquid crystal display according to claim 15, wherein the second storage capacitor counter voltage lags the first storage capacitor counter voltage by a phase difference of two horizontal scanning periods, the third storage capacitor counter voltage lags the first storage capacitor counter voltage by a phase difference of three horizontal scanning periods, and the fourth storage capacitor counter voltage lags the first storage capacitor counter voltage by a phase difference of one horizontal scanning period.

17. The liquid crystal display according to claim 16, comprising

two switching elements provided for the first sub-pixel and the second sub-pixel, respectively,

wherein the two switching elements are turned on and off by scan signal voltages supplied to a common scan line, display signal voltages are supplied to the respective sub-pixel electrodes and storage capacitor electrodes of the first sub-pixel and the second sub-pixel from a common signal line when the two switching elements are on, and voltages of the respective storage capacitor counter electrodes of the first sub-pixel and the second sub-pixel change after the two switching elements are turned off;

and

if Td denotes the time required for the first storage capacitor counter voltage to change for the first time after the two switching elements are turned off, Td is larger than 0 horizontal scanning period and smaller than two horizontal scanning periods.

18. The liquid crystal display according to claim 17, wherein the Td is approximately equal to one horizontal scanning period.

19. The liquid crystal display according to claim 1, wherein:

the plurality of storage capacitor trunks include a first storage capacitor trunk, second storage capacitor trunk, third storage capacitor trunk, fourth storage capacitor trunk, fifth storage capacitor trunk, and sixth storage capacitor trunk electrically independent of each other; and

if the storage capacitor line connected to the storage capacitor counter electrode of the first sub-pixel of the pixel located at the intersection of an arbitrary column and a given row n among rows formed by the plurality of pixels arranged in a row-and-column matrix is designated as CSBL_A_n, if the storage capacitor line connected to the storage capacitor counter electrode of the second sub-pixel is designated as CSBL_B_n, and if k is a natural number (including

     0);

CSBL_A_n+3*k is connected to the first storage capacitor trunk,

CSBL_B_n+3*k is connected to the second storage capacitor trunk,

CSBL_A_n+1+3*k is connected to the third storage capacitor trunk,

CSBL_B_n+1+3*k is connected to the fourth storage capacitor trunk,

CSBL_A_n+2+3*k is connected to the fifth storage capacitor trunk, and

CSBL_B_n+2+3*k is connected to the sixth storage capacitor trunk.

20. The liquid crystal display according to claim 19, wherein the periods of oscillation of first to sixth storage capacitor counter voltages supplied, respectively, by the first to sixth storage capacitor trunks are all 6 times the horizontal scanning period.

21. The liquid crystal display according to claim 1, wherein:

the plurality of storage capacitor trunks include a first storage capacitor trunk, second storage capacitor trunk, third storage capacitor trunk, fourth storage capacitor trunk, fifth storage capacitor trunk, sixth storage capacitor trunk, . . . , (L−

3)-th storage capacitor trunk, (L−

2)-th storage capacitor trunk, (L−

1)-th storage capacitor trunk, and L-th storage capacitor trunk for a total of L storage capacitor trunks electrically independent of each other; and

when ½

of the number L of the electrically independent storage capacitor trunks is an odd number, i.e., when L=2, 6, 10, . . . , or the like,

if the storage capacitor line connected to the storage capacitor counter electrode of the first sub-pixel of the pixel located at the intersection of an arbitrary column and a given row n among rows formed by the plurality of pixels is designated as CSBL_A_n, if the storage capacitor line connected to the storage capacitor counter electrode of the second sub-pixel is designated as CSBL_B_n, and if k is a natural number (including

     0);

CSBL_A_n+(L/2)*k is connected to the first storage capacitor trunk,

CSBL_B_n+(L/2)*k is connected to the second storage capacitor trunk,

CSBL_A_n+1+(L/2)*k is connected to the third storage capacitor trunk,

CSBL_B_n+1+(L/2)*k is connected to the fourth storage capacitor trunk,

CSBL_A_n+2+(L/2)*k is connected to the fifth storage capacitor trunk,

CSBL_B_n+2+(L/2)*k is connected to the sixth storage capacitor trunk,

. . .

CSBL_A_n+(L/2)−

2+(L/2)*k is connected to the (L−

3)-th storage capacitor trunk,

CSBL_B_n+(L/2)−

2+(L/2)*k is connected to the (L−

2)-th storage capacitor trunk,

CSBL_A_n+(L/2)−

1+(L/2)*k is connected to the (L−

1)-th storage capacitor trunk, and

CSBL_B_n+(L/2)−

1+(L/2)*k is connected to the L-th storage capacitor trunk.

22. The liquid crystal display according to claim 21, wherein the periods of oscillation of first to L-th storage capacitor counter voltages supplied, respectively, by the first to L-th storage capacitor trunks are all L times the horizontal scanning period.

23. The liquid crystal display according to claim 1, wherein:

the plurality of storage capacitor trunks include a first storage capacitor trunk, second storage capacitor trunk, third storage capacitor trunk, fourth storage capacitor trunk, fifth storage capacitor trunk, sixth storage capacitor trunk, seventh storage capacitor trunk, and eighth storage capacitor trunk electrically independent of each other; and

if the storage capacitor line connected to the storage capacitor counter electrode of the first sub-pixel of the pixel located at the intersection of an arbitrary column and a given row n among rows formed by the plurality of pixels is designated as CSBL_A_n, if the storage capacitor line connected to the storage capacitor counter electrode of the second sub-pixel is designated as CSBL_B n, and if k is a natural number (including

     0);

CSBL_A_n+8*k and CSBL_B_n+4+8*k are connected to the first storage capacitor trunk,

CSBL_B_n+8*k and CSBL_A_n+4+8*k are connected to the second storage capacitor trunk,

CSBL_A_n+1+8*k and CSBL_B_n+5+8*k are connected to the third storage capacitor trunk,

CSBL_B_n+1+8*k and CSBL_A_n+5+8*k are connected to the fourth storage capacitor trunk,

CSBL_A_n+2+8*k and CSBL_B_n+6+8*k are connected to the fifth storage capacitor trunk,

CSBL_B_n+2+8*k and CSBL_A_n+6+8*k are connected to the sixth storage capacitor trunk,

CSBL_A_n+3+8*k and CSBL_B_n+7+8*k are connected to the seventh storage capacitor trunk, and

CSBL_B_n+3+8*k and CSBL_A_n+7+8*k are connected to the eighth storage capacitor trunk.

24. The liquid crystal display according to claim 23, wherein the periods of oscillation of first to eighth storage capacitor counter voltages supplied, respectively, by the first to eighth storage capacitor trunks are all 8 times the horizontal scanning period.

25. The liquid crystal display according to claim 1, wherein:

the plurality of storage capacitor trunks include a first storage capacitor trunk, second storage capacitor trunk, third storage capacitor trunk, fourth storage capacitor trunk, fifth storage capacitor trunk, sixth storage capacitor trunk, seventh storage capacitor trunk, eighth storage capacitor trunk . . . , (L−

3)-th storage capacitor trunk, (L−

2)-th storage capacitor trunk, (L−

1)-th storage capacitor trunk, and L-th storage capacitor trunk for a total of L storage capacitor trunks electrically independent of each other; and

when ½

of the number L of the electrically independent storage capacitor trunks is an even number, i.e., when L=4, 8, 12, . . . , or the like,

if the storage capacitor line connected to the storage capacitor counter electrode of the first sub-pixel of the pixel located at the intersection of an arbitrary column and a given row n among rows formed by the plurality of pixels arranged in a row-and-column matrix is designated as CSBL_A_n, if the storage capacitor line connected to the storage capacitor counter electrode of the second sub-pixel is designated as CSBL_B_n, and if k is a natural number (including

     0);

CSBL_A_n+L*k and CSBL_B_n+(L/2)+L*k are connected to the first storage capacitor trunk,

CSBL_B_n+L*k and CSBL_A_n+(L/2)+L*k are connected to the second storage capacitor trunk,

CSBL_A_n+1+L*k and CSBL_B_n+(L/2)+1+L*k are connected to the third storage capacitor trunk,

CSBL_B_n+1+L*k and CSBL_A_n+(L/2)+1+L*k are connected to the fourth storage capacitor trunk,

CSBL_A_n+2+L*k and CSBL_B n+(L/2)+2+L*k are connected to the fifth storage capacitor trunk,

CSBL_B_n+2+L*k and CSBL_A_n+(L/2)+2+L*k are connected to the sixth storage capacitor trunk,

CSBL_A_n+3+L*k and CSBL_B_n+(L/2)+3+L*k are connected to the seventh storage capacitor trunk,

CSBL_B_n+3+L*k and CSBL_A_n+(L/2)+3+L*k are connected to the eighth storage capacitor trunk,

. . . ,

CSBL_A_n+(L/2)−

2+L*k and CSBL_B_n+L−

2+L*k are connected to the (L−

3)-th storage capacitor trunk,

CSBL_B_n+(L/2)−

2+L*k and CSBL_A_n+L−

2+L*k are connected to the (L−

2)-th storage capacitor trunk,

CSBL_A_n+(L/2)−

1+L*k and CSBL_B_n+L−

1+L*k are connected to the (L−

1)-th storage capacitor trunk, and

CSBL_B_n+(L/2)−

1+L*k and CSBL_A_n+L−

1+L*k are connected to the L-th storage capacitor trunk.

26. The liquid crystal display according to claim 25, wherein the periods of oscillation of first to L-th storage capacitor counter voltages supplied, respectively, by the first to L-th storage capacitor trunks are all L times the horizontal scanning period.

34. The liquid crystal display according to claim 9, wherein duty ratios of the storage capacitor counter voltages are all 1:

1.

35. The liquid crystal display according to claim 1, wherein the first sub-pixel in the any of the pixels is arranged in such a way as to be adjacent to the second sub-pixel of the pixel adjacent to the any of the pixels in the column direction and in each of the plurality of pixels, the first sub-pixel is arranged in such a way as to be adjacent to the second sub-pixel in the column direction.

36. The liquid crystal display according to claim 1, wherein the first sub-pixel and the second sub-pixel are approximately equal in area.

37. The liquid crystal display according to claim 1, wherein the second sub-pixel is larger in area than the first sub-pixel.

27. A liquid crystal display, comprising a plurality of pixels each of which has a liquid crystal layer and a plurality of electrodes for applying an electric field to the liquid crystal layer and which are arranged in a matrix of rows and columns, wherein:

each of the plurality of pixels has a first sub-pixel and a second sub-pixel which can apply mutually different voltages to the liquid crystal layer, where the first sub-pixel has a higher brightness than the second sub-pixel in certain gradations;

the first sub-pixel and the second sub-pixel each comprise;

a liquid crystal capacitor formed by a counter electrode and a sub-pixel electrode opposing the counter electrode via the liquid crystal layer, and

a storage capacitor formed by a storage capacitor electrode connected electrically to the sub-pixel electrode, an insulating layer, and a storage capacitor counter electrode opposing the storage capacitor electrode via the insulating layer;

the counter electrode is a single electrode shared by the first sub-pixel and the second sub-pixel, and the storage capacitor counter electrodes of the first sub-pixel and the second sub-pixel are electrically independent of each other;

the liquid crystal display further comprises a plurality of storage capacitor trunks electrically independent of each other, each of storage capacitor trunks being electrically connected to any of the storage capacitor counter electrodes of the first sub-pixel and the second sub-pixel in the plurality of pixels via a storage capacitor line, the storage capacitor counter electrode of the first sub-pixel of one of two adjacent pixels in the column direction is connected to a storage capacitor line electrically equivalent to the storage capacitor counter electrode of the second sub-pixel of the other; and

the number of the storage capacitor trunks electrically independent of each other amount the plurality of storage capacitor trunks is L or more (L is an even number), storage capacitor counter voltage supplied by each of the storage capacitor trunks is oscillating voltage, and the period of oscillation is 2*K*L (K is a positive integer) times a horizontal scanning period.

28. The liquid crystal display according to claim 27, wherein:

if the storage capacitor line connected to the storage capacitor counter electrode of the first sub-pixel of the pixel located at the intersection of an arbitrary column and a given row n among rows formed by the plurality of pixels arranged in a row-and-column matrix is designated as CSBL_(n)A and the storage capacitor line connected to the storage capacitor counter electrode of the second sub-pixel is designated as CSBL_(n)B,

CS buslines connected to the L electrically independent storage capacitor trunks satisfy relationships;

CSBL_(p+2*(1−

1))B, (p+2*(1−

1)+1)A,

CSBL_(p+2*(2−

1))B, (p+2*(2−

1)+1)A,

CSBL_(p+2*(3−

1))B, (p+2*(3−

1)+1)A,

. . .

CSBL_(p+2*(K−

1))B, (p+2*(K−

1)+1)A and

CSBL_(p+2*(1−

1)+K*L+1)B, (p+2*(1−

1)+K*L+2)A,

CSBL_(p+2*(2−

1)+K*L+1)B, (p+2*(2−

1)+K*L+2)A,

CSBL_(p+2*(3−

1)+K*L+1)B, (p+2*(3−

1)+K*L+2)A,

. . .

CSBL_(p+2*(K−

1)+K*L+1)B, (p+2*(3−

1)+K*L+2)A;

or

CSBL_(p+2*(1−

1)+1)B, (p+2*(1−

1)+2)A,

CSBL_(p+2*(2−

1)+1)B, (p+2*(2−

1)+2)A,

CSBL_(p+2*(3−

1)+1)B, (p+2*(3−

1)+2)A,

. . .

CSBL_(p+2*(K−

1)+1)B, (p+2*(K−

1)+2)A and

CSBL_(p+2*(1−

1)+K*L)B, (p+2*(1−

1)+K*L+1)A,

CSBL_(p+2*(2−

1)+K*L)B, (p+2*(2−

1)+K*L+1)A,

CSBL_(p+2*(3−

1)+K*L)B, (p+2*(3−

1)+K*L+1)A,

. . .

CSBL_(p+2*(K−

1)+K*L)B, (p+2*(K−

1)+K*L+1)A,

where p=1, 3, 5, or the like, or p=0, 2, 4, or the like.

29. The liquid crystal display according to claim 27, wherein K is 1 or 2, and L is any of 6, 8, 10, and 12.

30. The liquid crystal display according to claim 27, wherein the storage capacitor line is placed between two adjacent pixels in the column direction.

31. The liquid crystal display according to claim 30, comprising:

two switching elements provided for the first sub-pixel and the second sub-pixel, respectively; and

a scan line commonly connected to the two switching elements,

wherein the common scan line is placed between the first sub-pixel and the second sub-pixel.

32. The liquid crystal display according to claim 27, wherein the plurality of storage capacitor trunks are an even number of storage capacitor trunks grouped into pairs of storage capacitor trunks which supply storage capacitor counter voltages whose oscillations are 180 degrees out of phase with each other.

33. The liquid crystal display according to claim 27, wherein in any two adjacent pixels in the column direction, the storage capacitor counter electrode of the first sub-pixel of one pixel and the storage capacitorcounter electrode of the second sub-pixel of the other pixel are connected to a common storage capacitor line.