NORMALLY BLACK TRANSFLECTIVE LIQUID CRYSTAL DISPLAYS

• US 20100225855A1
• Filed: 09/15/2009
• Published: 09/09/2010
• Est. Priority Date: 03/09/2009
• Status: Abandoned Application

• Current Assignee: John Gilmore
• Original Assignee: Pixel Qi Corporation
• Inventors: Lu, Ruibo
• Application Number:
  US12/560,217
• Publication Number:
  US 20100225855A1
• Time in Patent Office: Days
• US Class Current: 349/96
• CPC Class Codes: G02F 1/133371 Cells with varying thickness of the liquid crystal layer
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 1/134372 for fringe field switching [FFS] where the common electrode is not patterned
• CPC Class Codes: G02F 1/13706 the liquid crystal having positive dielectric anisotropy
• CPC Class Codes: G02F 1/13712 the liquid crystal having negative dielectric anisotropy
• CPC Class Codes: G02F 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence
• CPC Class Codes: G02F 2201/122 having a particular pattern
• CPC Class Codes: G02F 2201/40 Arrangements for improving the aperture ratio
• CPC Class Codes: G02F 2202/36 Micro- or nanomaterials
• CPC Class Codes: G02F 2203/64 Normally black display, i.e. the off state being black
• CPC Class Codes: G02F 2413/01 Number of plates being 1
• CPC Class Codes: G02F 2413/02 Number of plates being 2
• CPC Class Codes: G02F 2413/05 Single plate on one side of the LC cell

Abstract

Techniques are provided for normally black multi-mode LCDs using homogeneously aligned liquid crystal materials which optical birefringence is electrically controllable. A light recycling/redirecting film may be added between a BLU and a nearby polarization layer to recycle backlight from a reflective part of an LCD unit structure into a transmissive part of the same structure to increase the optical output efficiency of the BLU. Electrodes for the transmissive part and the reflective part may be separately driven in various operating modes. Benefits include high transmittance, high reflectance, wide view angles, improved optical recycling efficiency, and low manufacturing costs.

Claims

1. A transflective liquid crystal display comprising a plurality of unit structures, each unit structure comprising:

a reflective part, comprising;

first portions of a first polarizing layer, a second polarizing layer, a first substrate layer, and a second substrate layer, wherein the second substrate layer is opposite to the first substrate layer;

a first common electrode portion;

a reflective electrode;

an over-coating layer adjacent to one of the first substrate layer and the second substrate layer;

a reflective layer adjacent to the first substrate layer;

a half-wave retardation film;

wherein the first substrate layer and the second substrate layer are between the first polarizing layer and the second polarizing layer;

a first liquid crystal layer portion of a liquid crystal layer between the first substrate layer and the second substrate layer, wherein liquid crystal molecules in the first liquid crystal layer portion is substantially homogeneously aligned along a direction in a voltage-off state;

a transmissive part, comprising;

second portions of the first polarizing layer, the second polarizing layer, the first substrate layer, and the second substrate layer;

a second liquid crystal layer portion of the liquid crystal layer between the first substrate layer and the second substrate layer;

a second common electrode portion; and

a transmissive electrode;

wherein a cell gap of the first liquid crystal layer portion is different from a cell gap of the second liquid crystal layer portion;

wherein liquid crystal molecules in the second liquid crystal layer portion is substantially homogeneously aligned along a second direction in the voltage-off state.

2. The transflective liquid crystal display according to claim 1, wherein the unit structure further comprises at least one color filter that covers at least an area of the transmissive part, wherein the unit structure is configured to express a color value associated with a color of the at least one color filter.

3. The transflective liquid crystal display according to claim 2, wherein the unit structure is a part of a composite pixel, and wherein the composite pixel comprises another unit structure that is configured to express a different color value other than the color value expressed by the unit structure.

4. The transflective liquid crystal display according to claim 1, wherein a normal direction of a surface of the first substrate layer is aligned in parallel with one or more of the first direction and the second direction.

5. The transflective liquid crystal display according to claim 1, wherein the unit structure further comprises one or more orientation films and wherein one or more of the first direction and the second direction are along a rubbing direction of at least one of the one or more orientation films.

6. The transflective liquid crystal display according to claim 1, wherein the half-wave retardation film is an in-cell retardation film that covers substantially only the reflective part.

7. The transflective liquid crystal display according to claim 1, wherein the unit structure comprises a first half-wave film and a second half-wave film, wherein the first half-wave film comprises a first half-wave film portion in the reflective part and a second half-wave film portion in the transmissive part, wherein the second half-wave film comprises a third half-wave film portion in the reflective part and a fourth half-wave film portion in the transmissive part, and wherein the half-wave retardation film is the third half-wave film portion in the reflective part.

8. The transflective liquid crystal display according to claim 6, wherein the second half-wave film is one of a uni-axial retardation film, a biaxial retardation film, or an oblique retardation film.

9. The transflective liquid crystal display according to claim 1, wherein the liquid crystal layer comprises a liquid crystal material which optical birefringence is electrically controllable.

10. The transflective liquid crystal display according to claim 1, wherein the half-wave retardation film and the first liquid crystal layer portion forms a wideband quarter-wave plate in the voltage-off state.

11. The transflective liquid crystal display according to claim 10, wherein the half-wave retardation film has an azimuth angle of θ

_h, wherein the first liquid crystal layer portion has an azimuth angle of θ

_q, and wherein the azimuth angles satisfy one of (1) 60≦

4θ

_h−

2θ

_q≦

120, or (2) −

120≦

4θ

_h−

2θ

_q≦

−

60.

12. The transflective liquid crystal display according to claim 1, wherein the unit structure comprises a first half-wave film and a second half-wave film, wherein the half-wave retardation film is a first portion of the second half-wave film, wherein the half-wave retardation film and the first liquid crystal layer portion in the voltage-off state forms a wideband quarter-wave plate in the reflective part, wherein a second portion of the second half-wave film and a first half of the second liquid crystal layer portion in the voltage-off state forms a first wideband quarter-wave plate in the transmissive part, and wherein the first half-wave film and a second remaining half of the second liquid crystal layer portion in the voltage-off state forms a second wideband quarter-wave plate in the transmissive part.

13. The transflective liquid crystal display according to claim 12, wherein the first half-wave film has an azimuth angle of θ

_h, wherein the first liquid crystal layer portion has an angle of θ

_q, wherein an azimuth angle of the second half-wave film is substantially θ

_h, and wherein the azimuth angles satisfy one of (1) 60≦

4θ

_h−

2θ

_q≦

120, or (2) −

120≦

4θ

_h−

2θ

_q≦

−

60.

14. The transflective liquid crystal display according to claim 1, wherein the unit structure comprises a first half-wave film, a second half-wave film, a first quarter-wave film, and a second quarter-wave film, wherein the half-wave retardation film is a part of the second half-wave film, wherein the first half-wave film and the first quarter-wave forms a first wideband quarter-wave plate in both the transmissive part and the reflective part, and wherein the second half-wave film and the second quarter-wave forms a second wideband quarter-wave plate in both the transmissive part and the reflective part.

15. The transflective liquid crystal display according to claim 14, wherein the first half-wave film has an azimuth angle of θ

_h, wherein the first quarter-wave film has an azimuth angle of θ

_q, wherein an azimuth angle of the second half-wave film is substantially θ

_h, wherein an azimuth angle of the second quarter-wave film is substantially θ

_h, and wherein the azimuth angles satisfy one of (1) 60≦

4θ

_h−

2θ

_q≦

120, or (2) −

120≦

4θ

_h−

2θ

_q≦

−

60.

16. The transflective liquid crystal display according to claim 1, wherein the unit structure comprises a switching element that is configured to control whether the reflective electrode is electrically connected to the transmissive electrode.

17. The transflective liquid crystal display according to claim 1, wherein the common electrode is located on a first side of the liquid crystal layer and the transmissive electrode and the reflective electrode are located on a second opposing side of the liquid crystal layer.

18. The transflective liquid crystal display according to claim 1, wherein the common electrode, the transmissive electrode, and the reflective electrode are located on a same side of the liquid crystal layer, wherein the unit structure further comprises a passivation layer, wherein the common electrode is located on a first side of the passivation layer, and wherein the transmissive electrode and the reflective electrode are located on a second opposing side of the passivation layer.

19. The transflective liquid crystal display according to claim 1, wherein at least one of the common electrode, the transmissive electrode and the reflective electrode is formed by a non-perforated planar layer of a conductive material.

20. The transflective liquid crystal display according to claim 1, wherein at least one of the common electrode, the transmissive electrode, and the reflective electrode is formed by a plurality of discrete conductive components, and wherein two neighboring discrete conductive components is spatially separated by a non-conductive gap.

21. The transflective liquid crystal display according to claim 1, wherein at least one of the common electrode, the transmissive electrode, and the reflective electrode comprises one or more openings each of which is void of a conductive material.

22. The transflective liquid crystal display according to claim 1, wherein one or more micro-protrusions are deposited on at least one of the common electrode, the transmissive electrode, and the reflective electrode.

23. The transflective liquid crystal display according to claim 1, wherein the common electrode comprises one or more openings each of which is void of a conductive material, wherein one or more micro-protrusions are deposited on the transmissive electrode and the reflective electrode, wherein the one or more openings and the one or more micro-protrusions form one or more pairs of electrode substructures each comprising one of the one or more openings and one of the one or more micro-protrusions.

24. The transflective liquid crystal display according to claim 1, wherein the unit structure further comprises a light recycling film between the first substrate layer and a backlight unit that redirects backlight from the reflective part to the transmissive part.

25. The transflective liquid crystal display according to claim 24, wherein the light recycling film is configured to turn incident light of any polarized state into redirected light with a particular polarization state.

26. A computer, comprising:

one or more processors;

a transflective liquid crystal display coupled to the one or more processors and comprising a plurality of unit structures, a unit structure comprising;

a reflective part, comprising;

first portions of a first polarizing layer, a second polarizing layer, a first substrate layer, and a second substrate layer, wherein the second substrate layer is opposite to the first substrate layer;

a first common electrode portion;

a reflective electrode;

an over-coating layer adjacent to one of the first substrate layer and the second substrate layer;

a reflective layer adjacent to the first substrate layer;

a half-wave retardation film;

wherein the first substrate layer and the second substrate layer are between the first polarizing layer and the second polarizing layer;

a first liquid crystal layer portion of a liquid crystal layer between the first substrate layer and the second substrate layer, wherein liquid crystal molecules in the first liquid crystal layer portion is substantially homogeneously aligned along a direction in a voltage-off state;

a transmissive part, comprising;

second portions of the first polarizing layer, the second polarizing layer, the first substrate layer, and the second substrate layer;

a second liquid crystal layer portion of the liquid crystal layer between the first substrate layer and the second substrate layer;

a second common electrode portion; and

a transmissive electrode;

wherein a cell gap of the first liquid crystal layer portion is different from a cell gap of the second liquid crystal layer portion;

wherein liquid crystal molecules in the second liquid crystal layer portion is substantially homogeneously aligned along a second direction in the voltage-off state.

27. The computer according to claim 26, wherein the unit structure further comprises at least one color filter that covers at least an area of the transmissive part, wherein the unit structure is configured to express a color value associated with a color of the at least one color filter.

28. The computer according to claim 26, wherein the half-wave retardation film is an in-cell retardation film that covers substantially only the reflective part.

29. The computer according to claim 26, wherein the unit structure comprises a first half-wave film and a second half-wave film, wherein the first half-wave film comprises a first half-wave film portion in the reflective part and a second half-wave film portion in the transmissive part, wherein the second half-wave film comprises a third half-wave film portion in the reflective part and a fourth half-wave film portion in the transmissive part, and wherein the half-wave retardation film is the third half-wave film portion in the reflective part.

30. The computer according to claim 26, wherein the liquid crystal layer comprises a liquid crystal material which optical birefringence is electrically controllable.

31. The computer according to claim 26, wherein the half-wave retardation film and the first liquid crystal layer portion forms a wideband quarter-wave plate in the voltage-off state.

32. The computer according to claim 26, wherein the unit structure comprises a first half-wave film and a second half-wave film, wherein the half-wave retardation film is a first portion of the second half-wave film, wherein the half-wave retardation film and the first liquid crystal layer portion in the voltage-off state forms a wideband quarter-wave plate in the reflective part, wherein a second portion of the second half-wave film and a first half of the second liquid crystal layer portion in the voltage-off state forms a first wideband quarter-wave plate in the transmissive part, and wherein the first half-wave film and a second remaining half of the second liquid crystal layer portion in the voltage-off state forms a second wideband quarter-wave plate in the transmissive part.

33. The computer according to claim 26, wherein the unit structure comprises a first half-wave film, a second half-wave film, a first quarter-wave film, and a second quarter-wave film, wherein the half-wave retardation film is a part of the second half-wave film, wherein the first half-wave film and the first quarter-wave forms a first wideband quarter-wave plate in both the transmissive part and the reflective part, and wherein the second half-wave film and the second quarter-wave forms a second wideband quarter-wave plate in both the transmissive part and the reflective part.

34. The computer according to claim 26, wherein the unit structure comprises a switching element that is configured to control whether the reflective electrode is electrically connected to the transmissive electrode.

35. The computer according to claim 26, wherein the common electrode, the transmissive electrode, and the reflective electrode are located on a same side of the liquid crystal layer, wherein the unit structure further comprises a passivation layer, wherein the common electrode is located on a first side of the passivation layer, and wherein the transmissive electrode and the reflective electrode are located on a second opposing side of the passivation layer.

36. The computer according to claim 26, wherein the common electrode comprises one or more openings each of which is void of a conductive material, wherein one or more micro-protrusions are deposited on the transmissive electrode and the reflective electrode, wherein the one or more openings and the one or more micro-protrusions form one or more pairs of electrode substructures each comprising one of the one or more openings and one of the one or more micro-protrusions.

37. The computer according to claim 26, wherein the unit structure further comprises a light recycling film between the first substrate layer and a backlight unit that redirects backlight from the reflective part to the transmissive part.

38. A method of fabricating a transflective liquid crystal display, comprising:

providing a plurality of unit structures, a unit structure comprising;

a reflective part, comprising;

first portions of a first polarizing layer, a second polarizing layer, a first substrate layer, and a second substrate layer, wherein the second substrate layer is opposite to the first substrate layer;

a first common electrode portion;

a reflective electrode;

an over-coating layer adjacent to one of the first substrate layer and the second substrate layer;

a reflective layer adjacent to the first substrate layer;

a half-wave retardation film;

wherein the first substrate layer and the second substrate layer are between the first polarizing layer and the second polarizing layer;

a first liquid crystal layer portion of a liquid crystal layer between the first substrate layer and the second substrate layer, wherein liquid crystal molecules in the first liquid crystal layer portion is substantially homogeneously aligned along a direction in a voltage-off state;

a transmissive part, comprising;

second portions of the first polarizing layer, the second polarizing layer, the first substrate layer, and the second substrate layer;

a second liquid crystal layer portion of the liquid crystal layer between the first substrate layer and the second substrate layer;

a second common electrode portion; and

a transmissive electrode;

wherein a cell gap of the first liquid crystal layer portion is different from a cell gap of the second liquid crystal layer portion;

wherein liquid crystal molecules in the second liquid crystal layer portion is substantially homogeneously aligned along a second direction in the voltage-off state.

39. The method according to claim 38, wherein the unit structure further comprises at least one color filter that covers at least an area of the transmissive part, wherein the unit structure is configured to express a color value associated with a color of the at least one color filter.

40. The method according to claim 38, wherein the liquid crystal layer comprises a liquid crystal material which optical birefringence is electrically controllable.