Electronic apparatus, liquid crystal display device and light guide plate

• US 6,854,857 B2
• Filed: 02/07/2003
• Issued: 02/15/2005
• Est. Priority Date: 06/11/2002
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Tanaka, Akira, Yamada, Hiroshi, Abe, Makoto, Aritake, Hirokazu, Hara, Yasushi
• Primary Examiner(s): LEE, Y MY QUACH
• Application Number:
  US10/359,719
• Publication Number:
  US 20030227768A1
• Time in Patent Office: 739 Days
• Field of Search: 362/26, 362/27, 362/31, 362/330, 362/331, 362/332, 362/339, 349/65
• US Class Current: 362/613
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

An electronic apparatus includes a liquid crystal display device. The liquid crystal display device comprises first and second light sources, a light guide plate, and a liquid crystal unit. The first light source is disposed on one of two opposing side surfaces of the light guide plate. The second light source is disposed on the other of the two opposing side surfaces of the light guide plate. A first plurality of substantially parallel grooves are formed in a first surface of the light guide plate which is substantially parallel with a display surface of the liquid crystal unit. A second plurality of substantially parallel grooves are formed in a second surface opposing the first surface of the light guide plate. At least one of a dimension and density of the first plurality of grooves substantially monotonically changes from one in the vicinity of one of the light sources to one in the vicinity of the other of the light sources.

Claims

1. An electronic apparatus comprising a liquid crystal display device, wherein

said liquid crystal display device comprises first and second light sources, a light guide plate, and a liquid crystal unit,

said first light source is disposed on one of two opposing side surfaces of said light guide plate,

said second light source is disposed on the other of said two opposing side surfaces of said light guide plate,

a first plurality of substantially parallel grooves are formed in a first surface of said light guide plate which is substantially parallel with a display surface of said liquid crystal unit,

a second plurality of substantially parallel grooves are formed in a second surface opposing said first surface of said light guide plate,

at least one of a dimension and density of said first plurality of grooves substantially monotonically changes from one in the vicinity of one of said light sources to one in the vicinity of the other of said light sources.

2. The electronic apparatus according to claim 1 wherein said first plurality of grooves are substantially in parallel with said second plurality of grooves.

3. The electronic apparatus according to claim 1 wherein one of a depth and density of said first plurality of grooves substantially gradually decreases from one in the vicinity of the one of said light sources to one in the vicinity of the other of said light sources.

4. The electronic apparatus according to claim 1 wherein both of a depth and density of said first plurality of grooves substantially gradually decrease from a first depth and a first density in the vicinity of the one of said light sources to a second depth and a second density in the vicinity of the other of said light sources.

5. The electronic apparatus according to claim 1 wherein said first plurality of grooves are substantially all of the grooves in said first surface of said light guide plate, and at least one of a depth and a reciprocal of a pitch of said first plurality of grooves substantially gradually decreases from one in the vicinity of said one of said light sources to one in the vicinity of the other of said light sources.

6. The electronic apparatus according to claim 1 wherein said first surface of said light guide plate is a surface closer to said liquid crystal unit, said first light source is a high brightness light source, and said second light source is a low brightness light source.

7. The electronic apparatus according to claim 1 wherein at least one of a dimension and density of said second plurality of grooves substantially monotonically changes from one in the vicinity of said other of said light sources to one in the vicinity of said one of said light sources.

8. The electronic apparatus according to claim 1 wherein one of a depth and density of said second plurality of grooves substantially gradually decreases from one in the vicinity of said other of said light sources to one in the vicinity of said one of said light sources.

9. The electronic apparatus according to claim 1 wherein said second plurality of grooves are substantially all of the grooves in said second surface of said light guide plate, and at least one of a depth and a reciprocal of a pitch of said second plurality of grooves substantially gradually decreases from one in the vicinity of said other of said light sources to one in the vicinity of said one of said light sources.

10. The electronic apparatus according to claim 1 wherein said second surface of said light guide plate is a surface remote from said liquid crystal unit, said first light source is a high brightness light source, and said second light source is a low brightness light source.

11. The electronic apparatus according to claim 1 wherein each of said first plurality of grooves is formed of a first sloping surface closer to said second light source and a second sloping surface closer to said first light source, and said first sloping surface 1s gentler than said second sloping surface.

12. The electronic apparatus according to claim 1 wherein each of said second plurality of grooves is formed of a third sloping surface closer to said first light source and a fourth sloping surface closer to said second light source, and said third sloping surface is gentler than said fourth sloping surface.

13. The electronic apparatus according to claim 1 wherein each of said first plurality of grooves is formed of a first sloping surface closer to said second light source and a second sloping surface closer to said first light source, and an angle formed between said first sloping surface and a first plane in which said first surface of said light guide plate lies is smaller than an angle formed between said second sloping surface and said first plane.

14. The electronic apparatus according to claim 1 wherein each of said second plurality of grooves is formed of a third sloping surface closer to said first light source and a fourth sloping surface closer to said second light source, and an angle formed between said third sloping surface and a second plane in which said second surface of said light guide plate lies is smaller than an angle formed between said fourth sloping surface and said second plane.

15. The electronic apparatus according to claim 1 wherein said liquid crystal device further comprises a lenticular lens disposed between said light guide plate and said liquid crystal unit, and said light guide plate directs light from said first and second light sources to said lenticular lens.

16. The electronic apparatus according to claim 1 wherein said first light source is a cold cathode fluorescent lamp.

17. The electronic apparatus according to claim 1 wherein said second light source is an LED.

18. The electronic apparatus according to claim 1 wherein said first and second light sources are cold-cathode fluorescent lamps having different magnitudes of brightness.

19. The electronic apparatus according to claim 1 wherein light from said second light source enters into said light guide plate through a light guide.

20. The electronic apparatus according to claim 1, further comprising control means for selectively operating said first and second light sources in accordance with a desired brightness required for said liquid crystal display device.

21. A liquid crystal display device comprising first and second light sources, a light guide plate and a liquid crystal unit, wherein

said first light source is disposed on one of two opposing side surfaces of said light guide plate,

said second light source is disposed on the other of said two opposing side surfaces of said light guide plate,

a first plurality of substantially parallel grooves are formed in a first surface of said light guide plate which is substantially parallel with a display surface of said liquid crystal unit,

a second plurality of substantially parallel grooves are formed in a second surface opposing said first surface of said light guide plate, and

at least one of a dimension and density of said first plurality of grooves substantially monotonically changes from one in one side of said light sources to one in the vicinity of the other side of said light sources.

22. A light guide plate comprising generally rectangular first and second opposing surfaces, wherein

a first plurality of substantially parallel grooves are formed in said first surface,

a second plurality of substantially parallel grooves are formed in said second surface, and

at least one of a dimension and density of said first plurality of grooves substantially monotonically changes from one of two opposing sides of said first surface to the other of said two sides.

23. The light guide plate according to claim 22 wherein

said first plurality of grooves are substantially parallel with said second grooves,

at least one of a dimension and density of said second plurality of grooves substantially monotonically changes from one of two opposing sides of said second surface to the other of said two sides,

said one side of said second surface is located near to said one side of said first surface, and

said other side of said second surface is located near to said other side of said first surface.

24. An electronic apparatus comprising a liquid crystal display device including a light guide plate,

wherein a first plurality of substantially parallel grooves are formed in a first surface of said light guide plate, a second plurality of substantially parallel grooves are formed in a second surface of said light guide plate that is opposite to the first surface, and at least one of a dimension and density of said first plurality of grooves substantially monotonically changes from one in the vicinity of a first light source to one in the vicinity of a second light source.

25. The electronic apparatus according to claim 24, wherein said first plurality of grooves are substantially 1n parallel with said second plurality of substantially parallel grooves formed in said second surface of said light guide plate.

26. The electronic apparatus according to claim 24, wherein one of a depth and density of said first plurality of grooves substantially gradually decreases from one in the vicinity of the first light source to one in the vicinity of the second light source.

27. The electronic apparatus according to claim 24, wherein both of a depth and density of said first plurality of grooves substantially gradually decrease from a first depth and a first density in the vicinity of the first light source to a second depth and a second density in the vicinity of the second light source.

28. The electronic apparatus according to claim 24, wherein a reciprocal of a pitch of said first plurality of grooves substantially gradually decreases from one in the vicinity of the light source to one in the vicinity of the second light source.

29. The electronic apparatus according to claim 24, wherein said first light source is a high brightness light source, and said second light source is a low brightness light source.

30. The electronic apparatus according to claim 24, wherein each of said first plurality of grooves is formed of a first sloping surface closer to said second light source and a second sloping surface closer to said first light source, and said first sloping surface is gentler than said second sloping surface.

31. The electronic apparatus according to claim 24, wherein each of said first plurality of grooves is formed of a first sloping surface closer to said second light source and a second sloping surface closer to said first light source, and an angle formed between said first sloping surface and a first plane in which said first surface of said light guide plate lies is smaller than an angle formed between said second sloping surface and said first plane.

32. The electronic apparatus according to claim 24, wherein said first light source is a cold cathode fluorescent lamp or an LED.

33. The electronic apparatus according to claim 24, wherein said first light source and second light sources are cold-cathode fluorescent lamps having different magnitudes of brightness.

34. The electronic apparatus according to claim 24, further comprising a controller selectively operating said first light source and said second light source in accordance with a desired brightness.