Backlight generating apparatus of a liquid crystal display device

• US 5,295,048 A
• Filed: 05/28/1992
• Issued: 03/15/1994
• Est. Priority Date: 08/24/1991
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Kae-seung, Park, Jong-ho
• Primary Examiner(s): Husar, Stephen F.
• Application Number:
  US07/889,197
• Time in Patent Office: 656 Days
• Field of Search: 362/26, 362/27, 362/31, 362/307, 362/343, 359/49, 359/50
• US Class Current: 362/26
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0041 provided in the bulk of the light guide
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements

Abstract

A backlight generating apparatus of an LCD device comprising a light-passing plate which is sloped with respect to a diffusing plate by a predetermined angle. The space between the two plates is filled with a diffusing material having a larger index of refraction than that of the light-passing plate. The present invention employs a diffusing plate with a transmissivity of over 30% to increase light efficiency, improve brightness, and decrease power consumption.

Claims

1. A backlight generating apparatus of an LCD device comprising:

a diffusing plate;

a light-passing plate and a reflecting plate sequentially stacked onto one another, said light-passing plate having a sloped surface which opposes said diffusing plate;

diffusing material having a selected index of refraction sandwiched between said light-passing plate and said diffusing plate; and

a lamp placed on an edge of said light-passing plate which is closest to said diffusing plate.

2. A backlight generating apparatus of an LCD device as claimed in claim 1, wherein said reflecting plate is installed so as to be sloped in the opposite direction from the sloped surface of said light-passing plate.

3. A backlight generating apparatus of an LCD device as claimed in claim 1, wherein the index of refraction of said diffusing material is larger than that of said light-passing plate.

4. A backlight generating apparatus of an LCD device as claimed in claim 2, wherein the index of refraction of said diffusing material is larger than that of said light-passing plate.

5. A backlight generating apparatus of an LCD device comprising:

a light-passing plate having a sloped upper surface and a lower surface;

a diffusing plate stacked on the sloped upper surface of said light-passing plate so that an aperture is created between said light-passing plate and said diffusing plate;

a reflecting plate opposing the lower surface of said light-passing plate; and

diffusing material disposed in the aperture between said diffusing plate and said light-passing plate having a lower surface that matches the slope of the upper surface of said light-passing plate.

6. A backlight generating apparatus of an LCD device according to claim 5, wherein said diffusing material is quartz.

7. A backlight generating apparatus of an LCD device according to claim 5, wherein said diffusing material has an index of refraction between 1.5 and 2.4.

8. A backlight generating apparatus of an LCD device according to claim 5, wherein said diffusing material has an index of refraction greater than that of said light-passing plate.

9. A backlight generating apparatus of an LCD device according to claim 5, wherein said light-passing plate has an index of refraction between 1.47 and 1.5.

10. A backlight generating apparatus of an LCD device according to claim 5, wherein said diffusing plate has a light transmissivity of over 30%.

11. A backlight generating apparatus of an LCD device according to claim 5, wherein said reflecting plate is positioned parallel to said diffusing plate.

12. A backlight generating apparatus of an LCD device according to claim 5, wherein said reflecting plate is sloped in the opposite direction from the slope of said light-passing plate.

13. A backlight generating apparatus of an LCD device comprising:

a light-passing plate having a sloped upper surface and a lower surface;

a diffusing plate stacked on the sloped upper surface of said light-passing plate so that an aperture is created between said light-passing plate and said diffusing plate;

diffusing material disposed in the aperture between said diffusing plate and said light-passing plate having a lower surface that matches the slope of the upper surface of said light-passing plate;

a lamp disposed proximate to an edge of said light-passing plate such that light generated by the lamp is processed through said light-passing plate and then irregularly reflected on the sloped face of said light-passing plate and part of the light is refracted by said diffusing material; and

means for re-reflecting light reflected by said light-passing plate and for directing the re-reflected light to said diffusing material.