LCD having a heat conduction means and a heat assist means

• US 5,742,366 A
• Filed: 02/28/1997
• Issued: 04/21/1998
• Est. Priority Date: 12/25/1992
• Status: Expired due to Fees

• Current Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Original Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Inventors: Imoto, Satoshi
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): TON, MINH TOAN T
• Application Number:
  US08/808,176
• Time in Patent Office: 417 Days
• Field of Search: 359/49, 359/50, 359/83, 349/62, 349/70, 349/58, 349/161
• US Class Current: 349/62
• CPC Class Codes: F21V 29/83 the elements having apertures, ducts or channels, e.g. heat radiation holes
• CPC Class Codes: F21V 29/89 Metals
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0071 with elongated shape, e.g. tube
• CPC Class Codes: G02B 6/0085 Means for removing heat created by the light source from the package heat extraction or cooling elements for semiconductor light sources in general H01L33/64
• CPC Class Codes: G02F 1/133308 Support structures for LCD panels, e.g. frames or bezels
• CPC Class Codes: G02F 1/133385 with cooling means, e.g. fans
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

A display device which suppresses the rise in temperature while making the distribution of temperature uniform, and features high display quality and reliability. The display device employs a light-guide plate provided with a heat conduction plate of a large heat conductivity on the back surface thereof. A gap is provided between the heat conduction plate and a holding member on the lower surface that holds the heat conduction plate, fluorescent tubes and the light-guide plate.

Claims

1. A display device including a planar display member constituted by liquid crystal display elements,

light-guide member opposed to said display member

a light-emitting member comprised of a tubular light source provided at least at an end portion of said light-guide member, and a holding member for holding at least said members as a unitary structure wherein

said planar display member is arranged at an upper surface of said light guide member,

a heat conduction member, said member being a heat conduction means constituted by a member having large heat conductivity is arranged at a lower side of the bottom surface of said light-guide member, and

a gap and a heat conduction assist means are arranged at a portion where said heat conduction member and said holding member are arranged next to each other, and wherein uniform display characteristic of said display member is obtained by changing the size or the shape of said gap and said heat conduction assist means.

2. A display device according to claim 1, wherein said light-guide means is a plate configured member made of a material having heat conductivity less than the heat conduction means.

3. A display device according to claim 1, wherein said light-emitting means is a fluorescent tube.

4. A display device according to claim 1, wherein said heat conduction means is a plate configured member made of a material having a large heat conductivity.

5. A display device according to claim 1, wherein said heat conduction means has an area approximately the same as the area of said planar display means.

6. A display device according to claim 1, wherein said reflection means is a reflecting sheet.

7. A display device according to claim 1, wherein the mechanism limiting the conduction of heat between said heat conduction means and said holding means is provided between said heat conduction means and said holding means close to said light-emitting means.

8. A display device according to claim 1 or 7 wherein the mechanism limiting the conduction of heat between said heat conduction means and said holding means, comprises at least one selected from the group consisting of a gap, a slit, a hole, and a window, provided between said heat conduction means and said holding means.

9. A display device according to claim 8, wherein said heat conduction means is directly and intimately adhered to said light-guide means.

10. A display device according to claim 1, wherein the reflection means is applied to a surface of said heat conduction means opposed to said light guide means.

11. A display device according to claim 10, wherein said heat conduction means directly and intimately adheres to said light-guide means.

12. A display device according to claim 1, wherein said heat conduction member and said heat conduction assist means are made of different materials having different characteristics of heat conductivity.

13. A display device according to claim 1, wherein said heat conduction member and said heat conduction assist means are made of the same material.

14. A display device according to claim 13 wherein said heat conduction member and said heat conduction assist means are made of a unitary member.

15. A display device according to claim 1 wherein said heat conduction member, said holding member and said heat conduction assist means are made of the same material.

16. A display device according to claim 15 wherein said heat conduction member, said holding member and said heat conduction assist means are made of a unitary member.

17. A display device according to claim 1 wherein said light-guide member is made of a material having a small conductivity.

18. A display device according to claim 1, wherein at least one of said heat conduction member and said heat conduction assist means are made of a material having a large heat conductivity.

19. A display device according to claim 1, wherein said heat conduction member has an area which is approximately the same as the area of said planar display member.

20. A display device according to claim 1 wherein reflection means is applied onto the surface of said heat conduction means opposed to said light-guide means.

21. A display device, comprising:

planar display means including liquid crystal display elements;

light-guide means having first and second opposite surfaces, said first surface being opposed to said display means;

light-emitting means provided at at least one end portion of said light-guide means;

reflection means covering said light-emitting means;

holding means holding at least one of said planar display means, said light-guide means, said light-emitting means, and said reflection means as a structure;

heat conduction means including a member having large heat conductivity at the structure, and opposed to said second surface of said light-guide means; and

a mechanism between said heat conduction means and said holding means close to said light emitting means, said mechanism limiting the conduction of heat between said heat conduction means and said holding means,

wherein the mechanism includes two portions, a first portion close to and parallel with the light-emitting means, a second portion between said heat conduction means and said holding means and perpendicular to the light-emitting means, the first portion having a greater ability of limiting heat conduction than the second portion.

22. A display device according to claim 21 wherein the mechanism limiting the conduction of heat between said heat conduction means and said holding means, comprises any one selected from the group consisting of a gap, a slit, a hole, and a window, provided between said heat conduction means and said holding means.

23. A display device according to claim 22, wherein said holding means and said heat conduction means are made of different materials, and a continuous circular gap is formed between said holding means and said heat conduction means.

24. A display device according to claim 23, wherein a heat conduction assist means is provided in a portion of said continuous circular gap to connect said holding means and said heat conduction means together.

25. A display device according to claim 24, wherein said heat conduction assist means is provided in at least one place in said gap that is formed in at least the portion in the direction at right angles with said light-emitting means.

26. A display device according to claim 25, wherein said heat conduction assist means is provided in at least one place in said gap formed in the portion in the direction parallel with said light-emitting means, and the number of said heat conduction assist means is smaller than the number of heat conduction assist means provided in the gap formed in the portion perpendicular to said light-emitting means.

27. A display device according to claim 25, wherein said heat conduction assist means is provided in at least one place in said gap formed in the portion in the direction in parallel with said light-emitting means, and the width of said heat conduction assist means is narrower than the width of the heat conduction means provided in the gap formed in the portion in the direction at right angles with said light-emitting means.

28. A display device according to claim 22, wherein said holding means and said heat conduction means are made of the same material, and a discrete gap is formed between said holding means and said heat conduction means via heat conduction assist means formed at predetermined portions.

29. A display device according to claim 28, wherein said heat conduction assist means is provided in at least one place in said gap formed in at least the portion in the direction at right angles with said light-emitting means.

30. A display device according to claim 29, wherein said heat conduction assist means is provided in at least one place in the gap formed in the portion in the direction in parallel with the light-emitting means, and the number of said heat conduction assist means is smaller than the number of the heat conduction assist means provided in the gap formed in the portion in the direction at right angles with the light-emitting means.

31. A display device according to claim 29, wherein said heat conduction assist means is provided in at least one place in said gap formed in the portion in the direction in parallel with said light-emitting means, and the width of said heat conduction assist means is narrower than the width of the heat conduction means provided in the gap formed in the portion in the direction at right angles with said light-emitting means.

32. A display device according to claim 24 or 29, wherein said heat conduction assist means has resiliency and imparts a biasing force to said heat conduction means to urge it toward said light-guide means at all times.

33. A display device according to claim 22, wherein said holding means and said heat conduction means are superposed one upon the other at the peripheral portions thereof, and the heat conduction assist means exist as spacers at predetermined portions in the superposed portion to form a gap or slit between said holding means and said heat conduction means.

34. A display device according to claim 33, wherein said heat conduction assist means is provided in at least one place in said gap or slit that is formed in at least the portion in the direction at right angles with said light-emitting means.

35. A display device according to claim 33, wherein said heat conduction assist means is provided in at least one place in said gap or slit formed in the portion in the direction in parallel with said light-emitting means, and the number of said heat conduction assist means is smaller than the number of the heat conduction assist means that are provided in the gap or slit formed in the portion in the direction at right angles with said light-emitting means.

36. A display device according to claim 33, wherein said heat conduction assist means is provided in at least one place in said gap or slit formed in the portion in the direction in parallel with said light-emitting means, and the width of said heat conduction assist means is narrower than the width of the heat conduction means provided in the gap or slit formed in the portion in the direction at right angles with said light-emitting means.

37. A display device including a planar display means constituted by liquid crystal display elements, a light-guide member opposed to said planar display means, a light-emitting member comprised of a tubular light source provided at least at an end portion of said light-guide member, and holding means for holding at least said members as a unitary structure, wherein

said planar display means has right angles with the side portion of said light-guide member on which said light-emitting member is arranged, and is arranged at an upper side of the upper surface of said light-guide member,

heat conduction means constituted by a member having a large heat conductivity and which has right angles with the side portion of said light guide member on which said light-emitting member is arranged, is arranged at a lower side of the bottom surface of said light-guide member, and

a first mechanism for limiting heat conductivity is provided between said heat conduction means and said holding means,

a second mechanism for limiting heat conductivity is provided at a portion at right angles with the longitudal direction of the tubular light-emitting member,

wherein an ability of limiting heat conductivity of the first mechanism is set to be larger than that of the second mechanism, when said first mechanism is provided at a portion which is close to said light emitting member and is parallel to the longitudinal direction of the tube thereof.

38. A display device according to claim 37, wherein said first mechanism is the one selected from a gap, a slit, a hole, and a window provided between said holding means and said heat conduction means.

39. A display device according to claim 38, wherein said holding means and said heat conduction means are superposed one upon the other at the peripheral portions thereof, and the heat conduction assist means exists as spacers at predetermined portions in the superposed portion to form a three-dimensional gap or slit between said holding means and said heat conduction means.

40. A display device according to claim 39, wherein said heat conduction assist means is provided in at least one place in said three-dimensional gap or slit that is formed in at least the portion in the direction at right angles with said light-emitting means.

41. A display device according to claim 39, wherein said heat conduction assist means is provided in at least one place in said three-dimensional gap or slit that is formed in at least the portion in the direction in parallel with said light-emitting means, and the number of said heat conduction assist means is smaller than the number of the heat conduction assist means that are provided in the three-dimensional gap or slit formed in the portion in the direction at right angles with said light-emitting means.

42. A display device according to claim 39, wherein said heat conduction assist means is provided in at least one place in said three-dimensional gap or slit that is formed in at least the portion in the direction in parallel with said light-emitting means, and the width of said heat conduction assist means is narrower than the width of the heat conduction assist means that are provided in the three-dimensional gap or slit formed in the portion in the direction at right angles with said light-emitting means.

43. A display device according to claim 38, wherein said holding means and said heat conduction means are made of different materials, and a continuous circular gap is formed between said holding means and said heat conduction means.

44. A display device according to claim 43, wherein said heat conduction assist means is provided in a portion of said continuous circular gap to connect said holding means and said heat conduction means together.

45. A display device according to claim 44, wherein said heat conduction assist means is provided in at least one place in said gap that is formed in at least the portion in the direction at right angles with said light emitting means.

46. A display device according to claim 45, wherein said heat conduction assist means is provided in at least one place in said gap formed in the portion in the direction in parallel with said light emitting means, and the number of said heat conduction assist means is set to be smaller than the number of said heat conduction assist means that are provided in said gap formed in the portion in the direction at right angles with said light-emitting means.

47. A display device according to claim 45, wherein said heat conduction assist means is provided in at least one place in said gap formed in the portion in the direction in parallel with said light emitting means, and the width of said heat conduction assist means is set to be narrower than the width of said heat conduction assist means that are provided in said gap formed in the portion in the direction at right angles with said light-emitting means.

48. A display device according to claim 44, wherein said holding means and said heat conduction means are made of the same material, and a discrete gap is formed between said holding means and said heat conduction means via heat conduction assist means formed at predetermined portions.

49. A display device according to claim 48, wherein said heat conduction assist means is provided in at least one place in said gap formed in at least the portion in the direction at right angles with said light-emitting means.

50. A display device according to claim 49, wherein said heat conduction assist means is provided in at least one place in said gap formed in the portion in direction in parallel with said light-emitting means, and the number of said heat conduction assist means is smaller than the number of heat conduction assist means provided in the gap formed in the portion in the direction at right angles with the light-emitting means.

51. A display device according to claim 49, wherein said heat conduction assist means is provided in at least one place in said gap formed in the portion in direction in parallel with said light-emitting means, and the width of said heat conduction assist means is narrower than the width of the heat conduction assist means provided in the gap formed in the portion in the direction at right angles with the light-emitting means.

52. A display device according to claim 44 or 49, wherein said heat conduction assist means has resiliency and imparts a biasing force to said heat conduction means to urge it toward said light-guide means at all times.