Semi-transmissive liquid crystal display device and electronic apparatus

• US 9,740,065 B2
• Filed: 08/01/2016
• Issued: 08/22/2017
• Est. Priority Date: 07/18/2012
• Status: Active Grant

• Current Assignee: Japan Display Incorporated
• Original Assignee: Japan Display Incorporated
• Inventors: Tamaki, Masaya, Maeda, Kazuyuki
• Primary Examiner(s): Crockett, Ryan
• Application Number:
  US15/225,226
• Publication Number:
  US 20160342006A1
• Time in Patent Office: 386 Days
• Field of Search: None
• CPC Class Codes: G02F 1/133357 Planarisation layers
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133512 Light shielding layers, e.g. black matrix G02F1/136209 takes precedence
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 1/134336 Matrix
• CPC Class Codes: G02F 1/134345 Subdivided pixels, e.g. for grey scale or redundancy
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/136286 Wiring, e.g. gate line, drain line
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G02F 2201/123 pixel
• CPC Class Codes: G02F 2413/02 Number of plates being 2
• CPC Class Codes: G02F 2413/04 Number of plates greater than or equal to 4
• CPC Class Codes: G02F 2413/06 Two plates on one side of the LC cell
• CPC Class Codes: G09G 2300/0456 with a reflective area and a transmissive area combined in one pixel, such as in transflectance pixels

Abstract

According to an aspect, a semi-transmissive liquid crystal display device includes a plurality of pixels arranged in a matrix, a plurality of reflective electrodes, a counter electrode facing the reflective electrode, and a liquid crystal layer. The reflective electrodes are provided for each of the pixels, and each of them includes a plurality of electrodes, with a combination of the areas of which area coverage modulation is performed by using n bits. The electrodes are configured such that a ratio of the sum of the perimeter(s) of electrode(s) corresponding to each bit of the n bits satisfies 1:2: . . . :2ⁿ⁻¹. The liquid crystal layer is provided between the reflective electrode and the counter electrode. The semi-transmissive liquid crystal display device is configured to carry out reflective display using the reflective electrode and carry out transmissive display using at least a space of the reflective electrode between the pixels.

Claims

1. A liquid crystal display device comprising:

a plurality of pixels arranged in a matrix;

a plurality of reflective electrode groups provided for each of the pixels, each of the reflective electrode groups including one or more reflective electrodes, with a combination of the areas of the reflective electrode groups being used to perform area coverage modulation using n bits, where n is an integer more than 2, each reflective electrode group corresponding to one of the n bits, the reflective electrode groups being configured such that a ratio of the sum of the perimeters of the reflective electrodes in each reflective electrode group corresponding to each bit of the n bits satisfies 2<sup>1−

1</sup>;

2<sup>2−

1</sup>;

. . . ;

2<sup>n−

1</sup>,

a counter electrode facing the plurality of reflective electrode groups; and

a liquid crystal layer provided between the reflective electrode groups and the counter electrode,

wherein the reflective electrodes include 2<sup>1−

1</sup> reflective electrode corresponding to first bit, 2<sup>2−

1</sup> reflective electrodes corresponding to second bit, . . . , and 2<sup>n−

1</sup> reflective electrodes corresponding to n-th bit,

wherein a total number of the reflective electrodes included in one pixel is a sum of a number of the reflective electrodes corresponding to each bit,

wherein the reflective electrodes have a same shape and a same size, and

wherein two or more of the reflective electrodes corresponding to the same bit are electrically connected to one another.

2. The liquid crystal display device according to claim 1, wherein

the reflective electrode groups include a first reflective electrode group that corresponds to the first bit, and

each of the reflective electrode groups except the first reflective electrode group includes one or more reflective electrodes provided at a first side of the first reflective electrode group and one or more reflective electrodes provided at a second side of the first reflective electrode group, the second side being opposed to the first side.

3. The liquid crystal display device according to claim 2, wherein a number of the reflective electrodes provided at the first side of the first reflective electrode group is equal to a number of the reflective electrodes provided at the second side of the first reflective electrode group.

4. The liquid crystal display device according to claim 3,

wherein the reflective electrodes of the one of the reflective electrode groups provided at the first side of the first reflective electrode group are electrically connected to one another, and

wherein the reflective electrodes provided at the second side of the first reflective electrode group are electrically connected to one another.

5. The liquid crystal display device according to claim 4,

wherein the one of the reflective electrode groups at the first side and the second side are electrically connected to one another via a first relay wiring and

wherein another one of the reflective electrode groups at the first side and the second side are electrically connected to one another via a second relay wiring that is different from the first relay wiring.

6. The liquid crystal display device according to claim 1, wherein

the reflective electrodes include a first reflective electrode, a second reflective electrode, and a third reflective electrode,

the reflective electrode groups being configured to perform the area coverage modulation by using 2 bits with an area ratio of 2:

1 with a combination of the areas of the first and second reflective electrodes with the third reflective electrode, and

the first and second reflective electrodes are arranged adjacent to each other and electrically connected on a same plane, and first reflective electrode is adjacent to the third reflective electrode.

7. The liquid crystal display device according to claim 1, wherein

a gap between the reflective electrodes adjacent to each other in one of the pixels is larger than a gap between the pixels adjacent to each other in a column direction.

8. The liquid crystal display device according to claim 1, wherein

a gap between a reflective electrode corresponding to a lower bit and an adjacent reflective electrode thereof in one of the pixels is larger than a gap between a reflective electrode corresponding to a higher bit and an adjacent reflective electrode thereof in the pixel.

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

parts of color filters included in the pixels adjacent to each other in a row direction overlap with each other.

10. The liquid crystal display device according to claim 1, further comprising

a scattering layer for scattering light to a side of a traveling direction of light reflected by the reflective electrode than the liquid crystal layer.

11. The liquid crystal display device according to claim 1, wherein

the liquid crystal display device has a display mode of a normally black mode.

12. The liquid crystal display device according to claim 1, wherein the pixels have a memory function.

13. The liquid crystal display device according to claim 12, wherein the pixels comprise a memory that stores therein data.

14. A liquid crystal display device comprising:

a plurality of pixels arranged in a matrix;

a plurality of reflective electrode groups provided for each of the pixels, each of the reflective electrode groups including one or more reflective electrodes, with a combination of the areas of the reflective electrode groups being used to perform area coverage modulation using n bits, where n is an integer more than 2, each reflective electrode group corresponding to one of the n bits, the reflective electrode groups being configured such that a ratio of the sum of the perimeters of the reflective electrodes in each reflective electrode group corresponding to each bit of the n bits satisfies 2<sup>1−

1</sup>;

2<sup>2−

1</sup>;

. . . ;

2<sup>n−

1</sup> in an opening of the pixel,

a counter electrode facing the plurality of reflective electrode groups; and

a liquid crystal layer provided between the reflective electrode groups and the counter electrode,

wherein the reflective electrodes include 2<sup>1−

1</sup> reflective electrode corresponding to first bit, 2<sup>2−

1</sup> reflective electrodes corresponding to second bit, . . . , and 2<sup>n−

1</sup> reflective electrodes corresponding to n-th bit,

wherein a total number of the reflective electrodes included in one pixel is a sum of a number of the reflective electrodes corresponding to each bit,

wherein the reflective electrodes have a same shape and a same size, and

wherein two or more of the reflective electrodes corresponding to the same bit are electrically connected to one another.

15. The liquid crystal display device according to claim 14, wherein

the reflective electrode groups include a first reflective electrode group that corresponds to the first bit, and

each of the reflective electrode groups except the first reflective electrode group includes one or more reflective electrodes provided at a first side of the first reflective electrode group and one or more reflective electrodes provided at a second side of the first reflective electrode group, the second side being opposed to the first side.

16. The liquid crystal display device according to claim 15, wherein a number of the reflective electrodes provided at the first side of the first reflective electrode group is equal to a number of the reflective electrodes provided at the second side of the first reflective electrode group.

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

wherein the reflective electrodes of one of the reflective electrode groups provided at the first side of the first reflective electrode group are electrically connected to one another, and

wherein the reflective electrodes of the one of the reflective electrode groups provided at the second side of the first reflective electrode group are electrically connected to one another.

18. The liquid crystal display device according to claim 17,

wherein the one of the reflective electrode groups at the first side and the second side are electrically connected to one another via a first relay wiring, and

wherein another one of the reflective electrode groups at the first side and the second side are electrically connected to one another via a second relay wiring that is different from the first relay wiring.

19. The liquid crystal display device according to claim 14, wherein

the reflective electrodes include a first reflective electrode, a second reflective electrode, and a third reflective electrode,

the reflective electrode groups being configured to perform the area coverage modulation by using 2 bits with an area ratio of 2:

1 with a combination of the areas of the first and second reflective electrodes with the third reflective electrode, and

the first and second reflective electrodes are arranged adjacent to each other and electrically connected on a same plane, and first reflective electrode is adjacent to the third reflective electrode.

20. The liquid crystal display device according to claim 14, wherein

a gap between the reflective electrodes adjacent to each other in one of the pixels is larger than a gap between the pixels adjacent to each other in a column direction.

21. The liquid crystal display device according to claim 14, wherein

a gap between a reflective electrode corresponding to a lower bit and an adjacent reflective electrode thereof in one of the pixels is larger than a gap between a reflective electrode corresponding to a higher bit and an adjacent reflective electrode thereof in the pixel.

22. The liquid crystal display device according to claim 14, wherein

parts of color filters included in the pixels adjacent to each other in a row direction overlap with each other.

23. The liquid crystal display device according to claim 14, further comprising

a scattering layer for scattering light to a side of a traveling direction of light reflected by the reflective electrode than the liquid crystal layer.

24. The liquid crystal display device according to claim 14, wherein

the liquid crystal display device has a display mode of a normally black mode.

25. The liquid crystal display device according to claim 14, wherein the pixels have a memory function.

26. The liquid crystal display device according to claim 25, wherein the pixels comprise a memory that stores therein data.