Transparent liquid crystal display device

• US 8,638,411 B2
• Filed: 12/01/2010
• Issued: 01/28/2014
• Est. Priority Date: 12/08/2009
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Park, Se-Hong, Kim, Eung-Do, Park, Jong-Sin
• Primary Examiner(s): Robinson, Mark
• Assistant Examiner(s): EL SHAMMAA, MARY A
• Application Number:
  US12/957,791
• Publication Number:
  US 20110299010A1
• Time in Patent Office: 1,154 Days
• Field of Search: 349/96, 349/97, 349/117, 349/119, 349/130, 349/129, 349/120
• US Class Current: 349/119
• CPC Class Codes: G02B 6/0023 provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
• CPC Class Codes: G02B 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 2413/01 Number of plates being 1
• CPC Class Codes: G02F 2413/02 Number of plates being 2

Abstract

Disclosed is a transparent liquid crystal display device provided with a compensation film of a liquid crystal panel to change the polarizing state of light in an image mode thereby enhancing a viewing angle characteristic, and the transparent liquid crystal display device may include a liquid crystal panel; a light source disposed at one side of a lower portion of the liquid crystal panel to emit light; a first polarizing plate for polarizing the light emitted from the light source; a light guide plate disposed at a lower portion of the liquid crystal panel to totally reflect the light polarized to an axis by the first polarizing plate to a lateral surface thereof and supply to the liquid crystal panel, and transmit natural light entered from a lower direction therethrough; a second polarizing plate disposed at an upper portion of the liquid crystal panel to control the amount of polarized light transmitting the liquid crystal panel; and a first positive A-film disposed at a lower portion of the liquid crystal panel to change the polarized state of the light outputted from the light guide plate and supplied to the liquid crystal panel, wherein the horizontal direction phase difference value (Re) is 120 nm.

Claims

1. A transparent liquid crystal display device, comprising:

a liquid crystal panel;

a light guide plate disposed at a lower portion of the liquid crystal panel, the light guide plate including;

a first surface facing the liquid crystal panel;

a second surface opposing to the first surface; and

a third surface perpendicular to the first and second surfaces;

a light source facing to the third surface of the light guide plate to supply the light to the light guide plate through the third surface thereof;

a first polarizing plate between the third surface of the light guide plate and the light source to polarize the light supplied to the light guide plate;

a second polarizing plate disposed at an upper portion of the liquid crystal panel to control the amount of the polarized light transmitting the liquid crystal panel; and

a first positive A-film disposed at a lower portion of the liquid crystal panel to change the polarized state of the light supplying to the liquid crystal panel through the light guide plate, the horizontal direction phase difference value (Re) of the first positive A-film being approximately 100-150 nm,

wherein an optical axis of the first polarizing plate is perpendicular to an optical axis of the second polarizing plate,

wherein the light from the light source is polarized by the first polarizing plate such that the polarized light is incident to the light guide plate through the third surface thereof to supply to the liquid crystal panel in order to display an image, and

wherein a non-polarized natural light is incident to the light guide plate through the second surface thereof to supply to the liquid crystal panel in order to display the image of the object at a rear portion of the light guide plate.

2. The transparent liquid crystal display device of claim 1, wherein the light source comprises a cathode ray fluorescent lamp or external electrode fluorescent lamp.

3. The transparent liquid crystal display device of claim 1, wherein the light source comprises a light-emitting device (LED).

4. The transparent liquid crystal display device of claim 1, wherein the light guide plate comprises:

a first refraction layer having a first refractive index; and

a second refraction layer having a second refractive index higher than the first refractive index which is disposed on the first refraction layer.

5. The transparent liquid crystal display device of claim 1, wherein the second polarizing plate comprises:

a polarizing body; and

a first supporting body and a second supporting body adhered to the upper and lower surfaces of the polarizing body, respectively.

6. The transparent liquid crystal display device of claim 5, wherein the first supporting body and second supporting body are composed of a triacetyl cellulose or a triacetyl cellulose with no phase difference (Rth).

7. The transparent liquid crystal display device of claim 6, wherein a phase difference value of the triacetyl cellulose is about 0-200 nm.

8. The transparent liquid crystal display device of claim 5, wherein the polarizing body is composed of a polyvinyl alcohol-based resin.

9. The transparent liquid crystal display device of claim 1, wherein the first positive A-film is composed of a material selected from the group consisting of a cycloolefin polymer film, a polycarbonate film, a UV-curable horizontally-aligned liquid crystal film, a polystyrene resin, and a polyethylene terephthalate.

10. The transparent liquid crystal display device of claim 1, wherein an optical axis of the first positive A-film is parallel to an optical axis of the second polarizing plate.

11. The transparent liquid crystal display device of claim 1, wherein a rubbing direction of the liquid crystal panel is perpendicular to an optical axis of the second polarizing plate.

12. The transparent liquid crystal display device of claim 1, wherein the liquid crystal panel includes an in-plane switching (IPS) mode liquid crystal panel and fringe-field switching (FFS) mode liquid crystal panel.

13. The transparent liquid crystal display device of claim 1, further comprising:

a triacetyl cellulose having a phase difference value of about 80-200 nm disposed between the first positive A-film and the liquid crystal panel.

14. The transparent liquid crystal display device of claim 1, further comprising:

a second positive A-film having a horizontal direction phase difference value (Re) of about 100-150 nm disposed between the liquid crystal panel and the second polarizing plate to change the polarizing state of the light outputted from the liquid crystal panel.

15. The transparent liquid crystal display device of claim 1, an optical axis of the second positive A-film is perpendicular to an optical axis of the second polarizing plate.

16. The transparent liquid crystal display device of claim 14, wherein the second positive A-film is composed of a material selected from the group consisting of a cycloolefin polymer film, a polycarbonate film, a UV-curable horizontally-aligned liquid crystal film, a polystyrene resin, and a polyethylene terephthalate.

17. The transparent liquid crystal display device of claim 1, further comprising:

a second positive A-film having a horizontal direction phase difference value (Re) of about 100-150 nm disposed between the liquid crystal panel and the second polarizing plate to change the polarizing state of the light outputted from the liquid crystal panel, and

a triacetyl cellulose having a phase difference value of about 80-200 nm disposed between the second positive A-film and the second polarizing plate.

18. The transparent liquid crystal display device of claim 1, further comprising:

a negative C-film having a thickness direction phase difference value (Rth) of about 80-150 nm disposed between the liquid crystal panel and the second polarizing plate to change the polarizing state of the light outputted from the liquid crystal panel.

19. The transparent liquid crystal display device of claim 18, wherein the negative C-film is composed of a material selected from the group consisting of a cycloolefin polymer film, a polycarbonate film, a UV-curable horizontally-aligned liquid crystal film, a polystyrene resin, and a polyethylene terephthalate.

20. The transparent liquid crystal display device of claim 1, further comprising:

a negative C-film having a thickness direction phase difference value (Rth) of about 80-150 nm disposed between the liquid crystal panel and the second polarizing plate to change the polarizing state of the light outputted from the liquid crystal panel, and

a triacetyl cellulose having a phase difference value of about 80-200 nm disposed between the negative C-film and the second polarizing plate.