Backlight device and liquid crystal display apparatus

• US 7,318,664 B2
• Filed: 12/19/2006
• Issued: 01/15/2008
• Est. Priority Date: 09/19/2003
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Yamada, Sinobu, Miyamura, Seiji, Kito, Shinsuke, Maruyama, Yuichiro, Iida, Kouji, Yokota, Kazuhiro, Oku, Takashi, Hatanaka, Masato
• Primary Examiner(s): TSO, LAURA K
• Application Number:
  US11/612,812
• Publication Number:
  US 20070086181A1
• Time in Patent Office: 392 Days
• Field of Search: 382/555, 382/800, 382/561, 382/612, 382/558, 382/627, 382/311, 382/330, 382/247, 382/248, 382/235, 382/244, 382/245, 382/246
• US Class Current: 362/555
• CPC Class Codes: G02B 5/0242 by means of dispersed particles
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G02F 1/133317 Intermediate frames, e.g. between backlight housing and front frame
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/133608 including particular frames or supporting means

Abstract

A light dimming dot pattern is provided for an LCD in which the diameter of dots is changed in a range from approximately 0.16 mm to approximately 0.65 mm depending on the distance of the dots from a fluorescent tube (13) in such a manner that the volume of the shielded light is increased and decreased at a location close to a position overlying the fluorescent tube (13) and at a location remote from the fluorescent tube (13), respectively. In this manner, a light dimming dot pattern with a transmittance for all light rays of approximately 62% (roughly in the vicinity of 62%), higher than the transmittance for all light rays in the conventional technique not higher than 50%, is produced. Consequently, the light of uniform high luminance may be produced without raising the luminance of the fluorescent tube (13), and hence an LCD of high luminance may be realized.

Claims

1. A diffusion member which diffuses light rays from a plurality of light sources, and which has a transmittance for all light rays of 50% or more and a cloud value of 90 to 99%, comprising:

a plurality of light dimming portions having a reflecting property, a light shielding property and diffusing property on a light incident surface or a light radiating surface of the diffusion member;

wherein,

said light dimming portions are generated such that a size of the light dimming portions varies so as to increase light volume to be shielded at a position close to a position directly above of said light sources and to decrease the light volume to be shielded at a position remote from said light sources.

2. The diffusion member according to claim 1, wherein said light dimming portions are arranged at a location corresponding to division by 24 to 48 of a spacing between neighboring ones of said light sources.

3. The diffusion member according to claim 1, wherein said light dimming portions are arranged in a staggered relationship along a column direction, and said diffusion member has transmittance for all light rays of 62 to 71%.

4. The diffusion member according to claim 1, wherein at least one of said light sources is a light emitting diode and a size of the light dimming portions is larger than an outer size of a light emitting part of the light emitting diode.

5. The diffusion member according to claim 4, having a transmittance for all light rays of 50 to 93%.

6. The diffusion member according to claim 1, wherein at least one of said light sources is a light emitting diode and one of said dimming portions faces to the light emitting diode in a one-for-one relationship.

7. The diffusion member according to claim 1, wherein said light dimming portions are formed by printing.

8. The diffusion member according to claim 1, wherein said light dimming portions are formed by printing.

9. The diffusion member according to claim 1, wherein said light dimming portions are formed by carrying out a number of times of printing, using different inks.

10. A backlight device comprising:

a plurality of light sources;

a first diffusion member which diffuses light rays radiated from said light sources;

a second diffusion member which diffuses light rays radiated from said first diffusion member, the second diffusion member having a transmittance for all light rays of 50% or more and a cloud value of 90 to 99%; and

a plurality of light dimming portions having a reflecting property, a light shielding property and diffusing property on a light incident surface or a light radiating surface of the second diffusion member,

wherein,

said light dimming portions are generated such that a size of the light dimming portions varies so as to increase light volume to be shielded at a position close to a position directly above of said light sources and to decrease the light volume to be shielded at a position remoter from said light sources.

11. A liquid crystal display apparatus comprising:

a light transmitting liquid crystal display panel; and

a backlight device for illuminating the liquid crystal display panel from a back side thereof, said backlight device including (a) a plurality of light sources, (b) a first diffusion member which diffuses light rays from said light sources, (c) a second diffusion member which diffuses light rays radiated from said first diffusion member, the second diffusion member having a transmittance for all light rays of 50% or more and a cloud value of 90 to 99%, and (d) a plurality of light dimming portions having a reflecting property, a light shielding property and diffusing property on a light incident surface or a light radiating surface of the second diffusion member,

wherein,

said light dimming portions are generated such that a size of the light dimming portions varies so as to increase light volume to be shielded at a position close to a position directly above of said light sources and to decrease the light volume to be shielded at a position remoter from said light sources.