Transmissive or reflective liquid crystal display and novel process for its manufacture

• US 20040170776A1
• Filed: 11/21/2003
• Published: 09/02/2004
• Est. Priority Date: 11/25/2002
• Status: Active Grant

• Current Assignee: E Ink California, LLC (E Ink Corporation)
• Original Assignee: SiPix Imaging, Inc. (E Ink Holdings Incorporated)
• Inventors: Liang, Rong-Chang, Tseng, Scott C-J, Li, Ying-Syi
• Granted Patent: US 7,141,279 B2
• Time in Patent Office: Days
• US Class Current: 428/1.2
• CPC Class Codes: B29D 11/0073 Optical laminates
• CPC Class Codes: C09K 2323/02 Alignment layer characterised by chemical composition
• CPC Class Codes: C09K 2323/05 Bonding or intermediate layer characterised by chemical composition, e.g. sealant or spacer
• CPC Class Codes: G02F 1/133377 Cells with plural compartments or having plurality of liquid crystal microcells partitioned by walls, e.g. one microcell per pixel
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/13475 in which at least one liquid crystal cell or layer is doped with a pleochroic dye, e.g. GH-LC cell G02F1/13476 takes precedence

Abstract

This invention relates to a liquid crystal display with improved contrast ratio, switching performance, reflectivity at the Dmin state and structural integrity, and methods for its manufacture.

Claims

1. A composition for the preparation of microcups used in a liquid crystal display which composition comprises a thermoplastics, a thermoset or a precursor thereof and liquid crystals.

2. The composition of claim 1 which is an embossable composition.

3. The composition of claim 1 wherein the liquid crystal has a concentration no greater than its solubility limit in the microcup composition.

4. The composition of claim 1 wherein said thermoplastic, thermoset or precursor thereof is a multifunctional acrylate or methacrylate, vinyl ether, epoxide and an oligomer or polymer thereof.

5. A composition for the preparation of microcups used in a liquid crystal display which composition comprises a thermoplastics, a thermoset or a precursor thereof and a speed enhancing comonomer or oligomer.

6. The composition of claim 5 which is an embossable composition.

7. The composition of claim 5 wherein said speed enhancing comonomer or oligomer comprises a poly(ethylene glycol) or poly(propylene glycol) moiety.

8. The composition of claim 7 wherein said poly(ethylene glycol) or poly(propylene glycol) moiety is poly(ethylene glycol) monoacrylate, poly(ethylene glycol) monomethacrylate, poly(ethylene glycol) diacrylate, poly(ethylene glycol) dimethacrylate, poly(propylene glycol) monoacrylate, poly(propylene glycol) monomethacrylate, poly(propylene glycol) diacrylate or poly(propylene glycol) dimethacrylate.

9. The composition of claim 5 wherein said thermoplastic, thermoset or precursor thereof is a multifunctional acrylate or methacrylate, vinyl ether, epoxide and an oligomer or polymer thereof.

10. A liquid crystal display comprising two or more layers of microcup array wherein said microcups are formed from a composition comprising a thermoplastics, a thermoset or a precursor thereof and liquid crystals.

11. The liquid crystal display of claim 10 wherein the liquid crystal has a concentration no greater than its solubility limit in the microcup composition.

12. The liquid crystal display of claim 10 wherein said thermoplastic, thermoset or precursor thereof is a multifunctional acrylate or methacrylate, vinyl ether, epoxide and an oligomer or polymer thereof.

13. The liquid crystal display of claim 10 wherein said two or more layers of microcup array are arranged in a staggered manner.

14. A liquid crystal display comprising two or more layers of microcup array wherein said microcups are formed from a composition comprising a thermoplastics, a thermoset or a precursor thereof and a speed enhancing comonomer or oligomer.

15. The liquid crystal display of claim 14 wherein said speed enhancing comonomer or oligomer comprises a poly(ethylene glycol) or poly(propylene glycol) moiety.

16. The liquid crystal display of claim 15 wherein said poly(ethylene glycol) or poly(propylene glycol) moiety is poly(ethylene glycol) monoacrylate, poly(ethylene glycol) monomethacrylate, poly(ethylene glycol) diacrylate, poly(ethylene glycol) dimethacrylate, poly(propylene glycol) monoacrylate, poly(propylene glycol) monomethacrylate, poly(propylene glycol) diacrylate or poly(propylene glycol) dimethacrylate.

17. The liquid crystal display of claim 14 wherein said thermoplastic, thermoset or precursor thereof is a multifunctional acrylate or methacrylate, vinyl ether, epoxide and an oligomer or polymer thereof.

18. The liquid crystal display of claim 14 wherein said two or more layers of microcup array are arranged in a staggered manner.

19. A process for the manufacture of a liquid crystal display of more than one layer of microcup array, which process comprises:

a) preparing separately two layers of microcup array, each on a conductor film; and

b) laminating one of the layers over the other optionally with an adhesive layer.

20. The process of claim 19 wherein said microcups are prepared from a composition comprising a thermoplastics, a thermoset or a precursor thereof and liquid crystals.

21. The process of claim 19 wherein said microcups are prepared from a composition comprising a thermoplastics, a thermoset or a precursor thereof and a speed enhancing comonomer or oligomer.

22. The process of claim 20 wherein step (a) is carried out by forming microcups over a conductor film, filling said microcups with a liquid crystal composition optionally comprising a guest dye and sealing the filled microcups with a polymeric sealing layer.

23. The process of claim 21 wherein step (a) is carried out by forming microcups over a conductor film, filling said microcups with a liquid crystal composition optionally comprising a guest dye and sealing the filled microcups with a polymeric sealing layer.

24. The process of claim 20 wherein step (b) is carried out by laminating one layer of the microcups over the other layer with the sealing sides of the two layers facing each other.

25. The process of claim 21 wherein step (b) is carried out by laminating one layer of the microcups over the other layer with the sealing sides of the two layers facing each other.

26. The process of claim 20 wherein one or both layers of microcup array is a full-color array prepared by a process comprising (i) laminating or coating said microcup array with a positively working photoresist, (ii) imagewise exposing and developing the positive photoresist to open microcups in a predetermined area, (iii) filling the opened microcups with a liquid crystal composition optionally containing guest dye(s) of a first primary color, (iv) sealing the filled microcups and (v) repeating the steps (ii)-(iv).

27. The process of claim 21 wherein one or both layers of microcup array is a full-color array prepared by a process comprising (i) laminating or coating said microcup array with a positively working photoresist, (ii) imagewise exposing and developing the positive photoresist to open microcups in a predetermined area, (iii) filling the opened microcups with a liquid crystal composition optionally containing guest dye(s) of a first primary color, (iv) sealing the filled microcups and (v) repeating the steps (ii)-(iv).

28. A process for the preparation of a liquid crystal display of more than one layer of microcup array, which process comprises:

a) forming a first layer of microcups on a conductor film;

b) forming a second layer of microcups on a transfer release substrate;

c) laminating said second layer over said first layer and removing said transfer release substrate;

d) optionally forming separately additional layers of microcups on transfer release substrates;

e) laminating said additional layers over the top layer in a stack of layers already formed and removing the transfer release substrates; and

f) laminating a second conductor film over the top most layer of said stack.

29. The process of claim 28 wherein said microcups are prepared from a composition comprising a thermoplastics, a thermoset or a precursor thereof and liquid crystals.

30. The process of claim 28 wherein said microcups are prepared from a composition comprising a thermoplastics, a thermoset or a precursor thereof and a speed enhancing comonomer or oligomer.

31. The process of claim 29 wherein step (a) is carried out by forming microcups on a conductor film, filling said microcups with a liquid crystal composition optionally comprising a guest dye and sealing the filled microcups with a polymeric sealing layer.

32. The process of claim 30 wherein step (a) is carried out by forming microcups on a conductor film, filling said microcups with a liquid crystal composition optionally comprising a guest dye and sealing the filled microcups with a polymeric sealing layer.

33. The process of claim 29 wherein steps (b) and (d) are carried out by forming microcups on said transfer release layer, filling said microcups with a liquid crystal composition optionally comprising a guest dye and sealing the filled microcups with a polymeric sealing layer.

34. The process of claim 30 wherein steps (b) and (d) are carried out by forming microcups on said transfer release layer, filling said microcups with a liquid crystal composition optionally comprising a guest dye and sealing the filled microcups with a polymeric sealing layer.

35. The process of claim 29 wherein step (c) is carried out by laminating said second layer over said first layer with the sealing sides of the two layers facing each other, followed by removing said transfer release substrate.

36. The process of claim 30 wherein step (c) is carried out by laminating said second layer over said first layer with the sealing sides of the two layers facing each other, followed by removing said transfer release substrate.

37. The process of claim 29 wherein step (e) is carried out by laminating said additional layers over the top layer in said stack of layers already formed, with the sealing sides of the additional layers facing the layers underneath, followed by removing said transfer release substrates.

38. The process of claim 30 wherein step (e) is carried out by laminating said additional layers over the top layer in said stack of layers already formed, with the sealing sides of the additional layers facing the layers underneath, followed by removing said transfer release substrates.

39. The process of claim 29 wherein step (f) is carried out by lamination with or without an adhesive layer.

40. The process of claim 30 wherein step (f) is carried out by lamination with or without an adhesive layer.

41. The process of claim 29 wherein said microcup array in step (a), (b), (d) or a combination thereof is a full-color array prepared by a process comprising (i) laminating or coating said microcup array with a positively working photoresist, (ii) imagewise exposing and developing the positive photoresist to open microcups in a predetermined area, (iii) filling the opened microcups with a liquid crystal composition optionally containing guest dye(s) of a first primary color, (iv) sealing the filled microcups and (v) repeating the steps (ii)-(iv).

42. The process of claim 30 wherein said microcup array in step (a), (b), (d) or a combination thereof is a full-color array prepared by a process comprising (i) laminating or coating said microcup array with a positively working photoresist, (ii) imagewise exposing and developing the positive photoresist to open microcups in a predetermined area, (iii) filling the opened microcups with a liquid crystal composition optionally containing guest dye(s) of a first primary color, (iv) sealing the filled microcups and (v) repeating the steps (ii)-(iv).

43. A process for the manufacture of a liquid crystal display of more than one layer of microcup array, which process comprises:

a) preparing a first layer of microcup array on a first conductor film;

b) preparing a second layer of microcup array on top of the first layer;

c) optionally preparing additional layers of microcup array on top of a stack of layers already formed; and

d) laminating a second conductor film on top of the top most layer of microcup array, optionally with an adhesive layer.

44. The process of claim 43 wherein said microcups are prepared from a composition comprising a thermoplastics, a thermoset or a precursor thereof and liquid crystals.

45. The process of claim 43 wherein said microcups are prepared from a composition comprising a thermoplastics, a thermoset or a precursor thereof and a speed enhancing comonomer or oligomer.

46. The process of claim 44 wherein steps (a), (b) and (c) are carried out by forming microcups over a conductor film, filling said microcups with a liquid crystal composition optionally comprising a guest dye and sealing the filled microcups with a polymeric sealing layer.

47. The process of claim 45 wherein steps (a), (b) and (c) are carried out by forming microcups over a conductor film, filling said microcups with a liquid crystal composition optionally comprising a guest dye and sealing the filled microcups with a polymeric sealing layer.

48. The process of claim 44 wherein said microcup array in step (a), (b), (c) or a combination thereof is a full-color array prepared by a process comprising (i) laminating or coating said microcup array with a positively working photoresist, (ii) imagewise exposing and developing the positive photoresist to open microcups in a predetermined area, (iii) filling the opened microcups with a liquid crystal composition optionally containing guest dye(s) of the a primary color, (iv) sealing the filled microcups and (v) repeating the steps (ii)-(iv).

49. The process of claim 45 wherein said microcup array in step (a), (b), (c) or a combination thereof is a full-color array prepared by a process comprising (i) laminating or coating said microcup array with a positively working photoresist, (ii) imagewise exposing and developing the positive photoresist to open microcups in a predetermined area, (iii) filling the opened microcups with a liquid crystal composition optionally containing guest dye(s) of the a primary color, (iv) sealing the filled microcups and (v) repeating the steps (ii)-(iv).