Polarization compensation film, display panel assembly and display device having the same

• US 20070024781A1
• Filed: 07/18/2006
• Published: 02/01/2007
• Est. Priority Date: 07/30/2005
• Status: Abandoned Application

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Song, Jun-Ho, Hirai, Akira, Ahn, Seon-Hong, Choi, Yoon-Seok
• Application Number:
  US11/488,314
• Publication Number:
  US 20070024781A1
• Time in Patent Office: Days
• US Class Current: 349/117
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133633 using mesogenic materials
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 2413/105 with varying inclination in thickness direction, e.g. hybrid oriented discotic LC

Abstract

A display panel assembly includes a display panel, a first polarizing plate disposed over the display panel, a second polarizing plate disposed under the display panel, and a polarization compensation film disposed over the first polarizing plate. The polarization compensation film includes a polarization prism film and a phase difference film. The polarization prism film divides a natural light wave into an ordinary wave with a first polarization state, and an extraordinary wave with a second polarization state. The phase difference film changes the second polarization state of the extraordinary wave into the first polarization state.

Claims

1. A polarization compensation film comprising:

a polarization prism film dividing an incident natural light wave into an ordinary wave with a first polarization state, and an extraordinary wave with a second polarization state that progresses in a direction inclined relative to the ordinary wave; and

a phase difference film changing the second polarization state of the extraordinary wave incident from the polarization prism film into the first polarization state.

2. The polarization compensation film of claim 1, wherein the polarization prism film comprises a first layer and a second layer having different refractive indexes from each other.

3. The polarization compensation film of claim 2, wherein an interface between the first layer and the second layer has a prism shape.

4. The polarization compensation film of claim 3, wherein the ordinary wave goes straight at the interface, and wherein the extraordinary wave is refracted from the interface by a predetermined angle.

5. The polarization compensation film of claim 2, wherein the second layer includes a liquid crystal layer having birefringence characteristics.

6. The polarization compensation film of claim 2, wherein the first layer includes a transparent resin layer.

7. The polarization compensation film of claim 1, wherein the phase difference film includes a liquid crystal layer having birefringence characteristics.

8. The polarization compensation film of claim 7, wherein liquid crystals contained in the liquid crystal layer are positioned inclined to an x-axis on an x-z plane, in which a z-axis indicates a direction substantially parallel with a progressing direction of the ordinary wave, the x-axis indicates a direction substantially parallel with an oscillating direction of the ordinary wave with the first polarization state, and a y-axis indicates a direction substantially perpendicular to the x-z plane.

9. The polarization compensation film of claim 7, wherein the liquid crystals are arranged along a lengthwise direction of a prism-shaped upper portion.

10. The polarization compensation film of claim 8, wherein an angle at which the liquid crystals form with respect to the x-axis is in a range of about 60°

to about 70°

.

11. The polarization compensation film of claim 9, wherein a thickness of the liquid crystal layer is in a range of about 4 μ

m to 4.5 μ

m.

12. The polarization compensation film of claim 7, wherein liquid crystals contained in the liquid crystal layer are arranged to be continuously changed by an angle of about 0°

to about 90°

with respect to a z-axis on the x-z plane, in which the z-axis indicates a direction substantially parallel with a progressing direction of the ordinary wave, an x-axis indicates a direction substantially parallel with an oscillating direction of the ordinary wave with the first polarization state, and a y-axis indicates a direction substantially perpendicular to x-z plane.

13. The polarization compensation film of claim 12, wherein the liquid crystals are arranged along a lengthwise direction of a prism-shaped upper portion.

14. The polarization compensation film of claim 13, wherein a thickness of the liquid crystal layer is in a range of about 6 μ

m to 20 μ

m.

15. The polarization compensation film of claim 1, wherein the phase difference film comprises at least two liquid crystal layers having birefringence characteristics, and wherein the liquid crystals contained in each liquid crystal layer are arranged to be continuously changed by an angle of about 0°

to about 90°

with respect to a z-axis on an x-z plane, in which the z-axis indicates a direction substantially parallel with a progressing direction of the ordinary wave, an x-axis indicates a direction substantially parallel with an oscillating direction of the ordinary wave with the first polarization state, and a y-axis indicates a direction substantially perpendicular to the x-z plane.

16. The polarization compensation film of claim 15, wherein a transparent adhesion layer is formed between the liquid crystal layers.

17. The polarization compensation film of claim 15, wherein the liquid crystals are arranged along a lengthwise direction of a prism-shaped upper portion.

18. The polarization compensation film of claim 15, wherein the liquid crystals are symmetrically arranged between adjacent liquid crystal layers.

19. The polarization compensation film of claim 15, wherein the liquid crystals are substantially identically arranged in each liquid crystal layer.

20. A method of manufacturing a polarization film comprising:

forming a transparent resin layer that has a prism-shaped upper portion;

forming a lower alignment layer on the transparent resin layer;

rubbing the lower alignment layer;

forming a liquid crystal layer having birefringence characteristics on the lower alignment layer; and

hardening the liquid crystal layer.

21. The method of claim 20, wherein forming the transparent resin layer comprises:

preparing a base film; and

forming a prism layer having a prism shape on the base film.

22. The method of claim 21, wherein a refractive index of the prism layer is substantially the same as that of a minor axis of a liquid crystal contained in the liquid crystal layer.

23. The method of claim 20, wherein an inclination angle of the prism shape is in a range of about 60°

to 70°

.

24. The method of claim 20, wherein a pitch size of the prism shape is in a range of about 10 μ

m to 20 μ

m.

25. The method of claim 20, further comprising thermally treating the lower alignment layer.

26. The method of claim 25, wherein thermally treating the lower alignment layer is performed at a temperature of no more than 130°

C.

27. The method of claim 20, wherein the lower alignment layer is rubbed along a direction substantially parallel to a lengthwise direction of the prism-shaped upper portion.

28. The method of claim 20, wherein the lower alignment layer is rubbed along a direction substantially perpendicular to a lengthwise direction of the prism-shaped upper portion.

29. The method of claim 20, wherein the liquid crystal layer is hardened by ultraviolet radiation.

30. A method of manufacturing a polarization film comprising:

forming a transparent resin layer that has a prism-shaped upper portion;

forming a lower alignment layer on the transparent resin layer;

rubbing the lower alignment layer;

forming a liquid crystal layer having birefringence characteristics;

forming a rubbed upper plate having substantially the same rubbing direction as that of the lower alignment layer;

combining the rubbed upper plate with the transparent resin layer, the liquid crystal layer being disposed between the rubbed upper plate and the transparent resin layer; and

hardening the liquid crystal layer.

31. The method of claim 30, further comprising removing the upper plate.

32. The method of claim 30, further comprising thermally treating the lower alignment layer.

33. A display panel assembly comprising:

a display panel displaying an image;

a first polarizing plate disposed over the display panel;

a second polarizing plate disposed under the display panel; and

a polarization compensation film disposed over the first polarizing plate, wherein the polarization compensation film comprises;

a polarization prism film dividing an incident natural light wave into an ordinary wave with a first polarization state, and an extraordinary wave with a second polarization state to form a predetermined angle with respect to the ordinary wave; and

a phase difference film changing the second polarization state of the extraordinary wave incident from the polarization prism film into the first polarization state.

34. The display panel assembly of claim 33, wherein the polarization prism film comprises a first layer and a second layer having different refractive indexes from each other, and wherein an interface between the first layer and the second layer has a prism shape.

35. The display panel assembly of claim 34, wherein the ordinary wave goes straight at the interface, and wherein the extraordinary wave is refracted from the interface by a predetermined angle with respect to the ordinary wave.

36. The display panel assembly of claim 34, wherein the first layer includes a transparent resin layer, and wherein the second layer includes a liquid crystal layer having birefringence characteristics.

37. The display panel assembly of claim 33, wherein the phase difference film includes a liquid crystal layer having birefringence characteristics.

38. The display panel assembly of claim 33, wherein the first polarizing plate includes a light transmission axis corresponding to the first polarization state.

39. The display panel assembly of claim 33, wherein the display panel comprises:

a lower substrate including a reflective region to reflect light incident from the first polarizing plate and a transmissive region to transmit light incident from the second polarizing plate;

an upper substrate combined to face the lower substrate; and

a liquid crystal layer disposed between the lower substrate and the upper substrate.

40. The display panel assembly of claim 39, wherein the lower substrate comprises:

a gate line;

a data line insulated with the gate line, the data line crossing the gate line;

a switching device connected with the gate line and the data line;

a transparent electrode connected with the switching device; and

a reflective electrode connected with the transparent electrode, the reflective electrode forming the reflective region.

41. The display panel assembly of claim 40, wherein the upper substrate comprises:

a color filter layer to produce color; and

a common electrode formed on the color filter layer to face the transparent electrode and the reflective electrode.

42. The display panel assembly of claim 33, further comprising a light-control film disposed over the polarization compensation film, changing a light path of a natural light wave incident from any direction into a direction perpendicular to the polarization compensation film.

43. The display panel assembly of claim 33, further comprising a λ

/4 film disposed between the display panel and the first polarizing plate, changing a circular polarization state into a linear polarization state and changing a linear polarization state into a circular polarization.

44. The display panel assembly of claim 33, further comprising a backlight unit disposed under the second polarizing plate, providing light to the second polarizing plate.

45. The display panel assembly of claim 44, wherein the display panel comprises any one selected from the group consisting of a reflective panel and a transflective panel.

46. A display panel assembly comprising:

a display panel displaying an image;

a first polarizing plate disposed over the display panel;

a second polarizing plate disposed under the display panel;

a polarization compensation film disposed under the second polarizing plate; and

a backlight unit disposed under the second polarizing plate, providing light to the second polarizing plate,

wherein the polarization compensation film comprises;

a polarization prism film dividing a natural light wave incident from the backlight assembly into an ordinary wave with a first polarization state corresponding to a light transmissive axis of the second polarizing plate, and an extraordinary wave with a second polarization state progressing to form a predetermined angle with respect to the ordinary wave; and

a phase difference film changing the second polarization state of the extraordinary wave incident from the polarization prism film into the first polarization state.

47. The display panel assembly of claim 46, wherein the display panel includes a transmissive panel.