Phase delay element for transmissive and reflective type liquid crystal display

• US 20060012737A1
• Filed: 07/19/2005
• Published: 01/19/2006
• Est. Priority Date: 07/19/2004
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Uh, Kee-Han, Hirai, Akira, Yun, Jin-Hyuk, Park, Min-Soo
• Granted Patent: US 7,656,480 B2
• Time in Patent Office: Days
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133526 Lenses, e.g. microlenses or Fresnel lenses
• 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 2413/02 Number of plates being 2

Abstract

A phase delay element includes a brightness enhancement layer intermediate a reflection layer and an artificial light. The brightness enhancement layer is defined by a first surface and an opposite second surface. The first surface faces the reflection layer. A first light from the artificial light is incident on the second surface. A phase of the first light is delayed by about ¼ phase (λ/4) so that a second light is emitted from the first surface toward the reflection layer. The second light is reflected from the reflection layer so that a third light is emitted from the reflection layer toward the first surface. A phase of the third light is delayed by about ¼ phase (λ/4) so that a fourth light is emitted from the second surface. Therefore, a portion of the artificial light, which is reflected from the reflection layer, is recycled to improve a luminance of an LCD apparatus.

Claims

1. A transmissive and reflective type LCD comprising:

a first substrate;

a second substrate having an inner surface that is arranged so as to face the first substrate;

a liquid crystal layer formed between the first substrate and the second substrate;

a first polarizing plate formed on an outer surface of the first substrate;

a backlight arranged at a rear side of the first polarizing plate; and

a brightness enhancement layer arranged between the backlight and a reflection layer disposed with one of the liquid crystal layer and the first and second substrates, the brightness enhancement layer configured to delay a phase of the light that has passed through the brightness enhancement layer by about 1/4 phase (λ

/4) so that a right circularly polarized light is emitted from the brightness enhancement layer toward a backside defining the first substrate.

2. The transmissive and reflective type LCD of claim 1, wherein the brightness enhancement layer is integrally formed with one of the liquid crystal layer and the first and second substrates.

3. The transmissive and reflective type LCD of claim 1, wherein the brightness enhancement layer is separately formed from one of the liquid crystal layer and the first and second substrates.

4. The transmissive and reflective type LCD of claim 1, wherein the brightness enhancement layer includes a birefringent film, an alignment film of a liquid crystal polymer, and an alignment layer of the liquid crystal polymer that is fixed.

5. The transmissive and reflective type LCD of claim 4, wherein the brightness enhancement layer includes a cholesteric liquid crystal that is an ultraviolet curable liquid crystal polymer.

6. The transmissive and reflective type LCD of claim 4, wherein the brightness enhancement layer includes a solidified cholesteric liquid crystal.

7. The transmissive and reflective type LCD of claim 1, wherein the brightness enhancement layer is defined by a first surface and an opposite second surface that is integrally formed with the first surface, the first surface being disposed facing a reflection layer, wherein a first light is incident on the second surface and a phase of the first light is delayed by about 1/4 phase (λ

/4) to obtain a second light that is provided from the first surface toward the reflection layer, the second light being reflected from the reflection layer to become a third light that is emitted from the reflection layer toward the first surface, a phase of the third light is delayed by about 1/4 phase (λ

/4) to obtain a fourth light that is emitted from the second surface of the brightness enhancement layer.

8. The transmissive and reflective type LCD of claim 7, wherein the first light is circularly polarized, the second light and the third light are vertically polarized, and the fourth light is circularly polarized in a same direction as a direction of the first light.

9. The phase delay element of claim 7, wherein the first surface is defined by an uneven surface.

10. The transmissive and reflective type LCD of claim 7, wherein the second surface is defined by an uneven surface.

11. The phase delay element of claim 7, wherein the second surface and the first surface of the brightness enhancement layer are solidified cholesteric liquid crystal.

12. The transmissive and reflective type LCD of claim 7, wherein the first surface of the brightness enhancement layer is defined by concave and convex portions.

13. The transmissive and reflective type LCD of claim 12, wherein the first surface of the brightness enhancement layer is defined by concave and convex portions that are rounded.

14. The transmissive and reflective type LCD of claim 12, wherein each of the concave portions of the first surface of the brightness enhancement layer is defined with a substantially flat section, and each of the convex portions of the first surface of the brightness enhancement layer is defined with a rounded section.

15. A method of manufacturing a phase delay element, comprising:

forming a liquid crystal layer on an alignment layer disposed on a substrate;

patterning and solidifying the liquid crystal layer to form a brightness enhancement layer; and

forming an embossed pattern on the brightness enhancement layer.

16. The method of claim 15, wherein said substrate is one of a transparent substrate and a glass substrate.

17. The method of claim 15, further comprising:

aligning the liquid crystal layer containing a photoresist imparting agent on a printing film;

irradiating ultraviolet light on the aligned liquid crystal layer to solidify the liquid crystal layer;

disposing the solidified liquid crystal layer with the substrate; and

removing the printing film from the liquid crystal layer, the liquid crystal layer being patterned and solidified forming the brightness enhancement layer.

18. The method of claim 15, further comprising:

forming the alignment layer on a photoresist film having an embossed surface;

irradiating ultraviolet light on the liquid crystal layer;

disposing the liquid crystal layer with the substrate; and

removing the photoresist film from the liquid crystal layer, the liquid crystal layer being patterned and solidified forming the brightness enhancement layer.

19. The method of claim 15 wherein the alignment layer is a photoresist aligning material, the method further comprising:

coating the photoresist aligning material in a reflection region on the substrate having the reflection region and a transmission region;

aligning the photoresist aligning material formed in the reflection region; and

forming the liquid crystal layer in the reflection region to align the liquid crystal layer in the reflection region, the liquid crystal layer being solidified and formed in the reflection region forming the brightness enhancement layer.

20. A method of manufacturing a substrate comprising:

forming a switching element including a pixel area, the pixel area defined by a reflection region and a transmission region;

forming a brightness enhancement layer aligned with the reflection region, the brightness enhancement layer configured to delay a phase of a backside light passing therethrough by about 1/4 phase (λ

/4);

forming a pixel electrode in the transmission region; and

forming a reflection layer in the reflection region.

21. The method of claim 20, further comprising:

forming the switching element on an insulating plate;

forming an organic insulating layer in the reflection region;

forming the brightness enhancement layer on the organic insulating layer; and

forming the pixel electrode on the brightness enhancement layer.

22. The method of claim 20, further comprising:

forming the brightness enhancement layer on an insulating plate;

forming the switching element on the insulating plate having the brightness enhancement layer;

forming an organic insulating layer in the reflection region; and

forming the pixel electrode on the brightness enhancement layer.

23. The method of claim 20, further comprising:

forming the brightness enhancement layer on an insulating plate;

forming the reflection layer on the brightness enhancement layer; and

forming a color filter on the reflection layer and in the transmission region.

24. The method of claim 23, further including:

forming a coating layer on the color filter; and

forming a common electrode on the coating layer.

25. The method of claim 20, further comprising:

forming the switching element on an insulating plate;

forming the brightness enhancement layer on the insulating plate;

forming an organic insulating layer on the brightness enhancement layer; and

forming a pixel electrode in the transmission region on the organic insulating layer.

26. A substrate comprising:

an insulating plate having a pixel area, the pixel area defined by a reflection region and a transmission window;

a switching element formed in the pixel area;

a pixel electrode electrically connected to the switching element;

a reflection layer disposed in alignment with the reflection region, the reflection layer being receptive to a front light emitted from a viewer'"'"'s side outside of the substrate being reflected from the reflection layer toward the viewer'"'"'s side, the reflection layer being receptive to a backside light emitted from a backside of the substrate opposite the viewer'"'"'s side being reflected from the reflection layer toward the backside; and

a brightness enhancement layer formed intermediate the reflection layer and the backside light, wherein the backside light being emitted from the backside toward the reflection layer through the brightness enhancement layer becomes a reflection light being emitted from the reflection layer toward the backside through the brightness enhancement layer.

27. The substrate of claim 26, wherein the brightness enhancement layer delays a phase of the backside light providing a phase-delayed backside light to the reflection layer, and the brightness enhancement layer delays a phase of the reflection light to providing a phase-delayed reflection light to the backside.

28. The substrate of claim 26, wherein the brightness enhancement layer delays a phase of the backside light by about 1/4 phase providing a phase-delayed backside light to the reflection layer, and the brightness enhancement layer delays a phase of the reflection light by about 1/4 phase providing a phase-delayed reflection light to the backside.

29. The substrate of claim 26, wherein the brightness enhancement layer is defined having a substantially identical thickness.

30. The substrate of claim 26, wherein the brightness enhancement layer is defined by a first surface and an opposite second surface integrally formed with the first surface, the first surface being disposed facing a reflection layer, the first and second surfaces each being substantially non-planar.

31. The substrate of claim 26, wherein the brightness enhancement layer is disposed between the insulating plate and the switching element.

32. The substrate of claim 26, wherein the brightness enhancement layer is disposed between the switching element and the pixel electrode.

33. The substrate of claim 26, further including:

an organic insulating layer disposed over the switching element of which a drain electrode is exposed in the reflection region, the substrate being exposed in the transmission window; and

a passivation layer disposed over the organic insulating layer, the passivation layer being formed on the pixel electrode connected with the reflection layer,

wherein the reflection layer is formed in an upper area defining the passivation layer corresponding to the reflection region.

34. The substrate of claim 33, wherein the brightness enhancement layer is formed on a surface of the organic insulating layer.

35. The substrate of claim 26, further comprising:

a color filter formed in the pixel area; and

a common electrode layer formed on the insulating plate having the color filter in the pixel area.

36. The substrate of claim 26, wherein the brightness enhancement layer is disposed under the transmission window and delays a phase of the backside light by about 1/4 phase providing a phase-delayed backside light to the transmission window.

37. A phase delay element for a LCD apparatus comprising:

a brightness enhancement layer disposed between a backlight and a reflection layer, the brightness enhancement layer defined by a bottom member and a counter member, the counter member being integrally formed with the bottom member, the counter member being disposed facing the reflection layer,

wherein a first light having a wavelength phase (λ

) incident on the bottom member is delayed by about 1/4 phase (λ

/4) emitting a second light that from the counter member toward the reflection layer, the second light being reflected from the reflection layer to become a third light that is emitted from the reflection layer toward the counter member, a phase of the third light is delayed by about 1/4 phase (λ

/4) passing through the brightness enhancement layer emitting a fourth light from the bottom member.

38. The phase delay element of claim 37, wherein the first light is circularly polarized, the second light and the third light are vertically polarized, and the fourth light is circularly polarized in a same direction as a direction of the first light.

39. The phase delay element of claim 37, wherein the counter member is defined with a substantially non-planar surface.

40. The phase delay element of claim 37, wherein the bottom member is defined with a substantially non-planar surface.

41. The phase delay element of claim 37, wherein the bottom member and the counter member are solidified cholesteric liquid crystal.

42. The phase delay element of claim 37, wherein the counter member is defined with concave and convex portions.

43. The phase delay element of claim 42, wherein the concave and convex portions of the counter member are rounded.

44. The phase delay element of claim 42, wherein the concave portions of the counter member are defined with flat sections, and the convex portions of the counter member are defined by rounded sections.

45. An LCD apparatus comprising:

a first side;

a second side opposite the first side defining the LCD apparatus;

a liquid crystal layer proximate the second side, the liquid crystal layer receptive to displaying images;

a first polarizer receptive to emitting a horizontally polarized light when a light is incident on the first polarizer from either side of the first polarizer;

a lower 1/4 phase (λ

/4) retardation film intermediate the liquid crystal layer and the first polarizer, the lower 1/4 phase (λ

/4) retardation film receptive to emitting a circularly polarized light when the horizontally polarized light is incident on the lower 1/4 phase (λ

/4) retardation film from the first side, and the horizontally polarized light is emitted from the lower 1/4 phase (λ

/4) retardation film toward the first side when the circularly polarized light is incident on the lower 1/4 phase (λ

/4) retardation film from the second side;

a brightness enhancement film intermediate the liquid crystal layer and the 1/4 phase (λ

/4) retardation film, the brightness enhancement film receptive to emitting a vertically polarized light therefrom toward the second side when the circularly polarized light is incident on the brightness enhancement film from the first side, and the brightness enhancement film receptive to emitting a circularly polarized light therefrom when the vertically polarized light is incident on the brightness enhancement film from the second side; and

a reflection layer intermediate the liquid crystal layer and the brightness enhancement film, the reflection layer receptive to reflecting the vertically polarized light to the brightness enhancement film, the vertically polarized light being incident on the reflection layer from the first side.

46. The LCD apparatus of claim 45, wherein the liquid crystal layer displays images in response to the vertically polarized light provided from the brightness enhancement film.

47. The LCD apparatus of claim 45, wherein the brightness enhancement film is formed in a reflection region corresponding with where the reflection layer is formed.

48. The LCD apparatus of claim 45, wherein the brightness enhancement film is formed in a reflection region and a transmission region, wherein the reflection region is a region in which the reflection layer is formed and the transmission region is a region in which the reflection layer is absent.

49. The LCD apparatus of claim 45, further comprising:

an upper 1/4 phase (λ

/4) retardation film receptive to delaying a phase of light passing through the liquid crystal layer by about 1/4 phase; and

an upper polarizer receptive to passing a portion of the 1/4 phase (λ

/4) delayed light from the upper 1/4 phase (λ

/4) retardation film, wherein the upper polarizer has a predetermined polarizing axis and the upper 1/4 phase (λ

/4) retardation film is intermediate the upper polarizer and the liquid crystal layer.