Optical component for liquid crystal display

• US 7,085,060 B2
• Filed: 09/29/2003
• Issued: 08/01/2006
• Est. Priority Date: 09/30/2002
• Status: Expired due to Fees

• Current Assignee: Omron Corporation
• Original Assignee: Omron Corporation
• Inventors: Kawato, Kenji, Aoyama, Shigeru, Matsushita, Motohiko, Matsui, Yuki, Funamoto, Akihiro
• Primary Examiner(s): Lavarias, Arnel C.
• Application Number:
  US10/676,855
• Publication Number:
  US 20040105157A1
• Time in Patent Office: 1,037 Days
• Field of Search: 359/599, 359/584, 359/619, 359/620, 359/625, 359/626, 359/627, 359/628, 359/831, 359/837, 349/62, 349/64, 349/65, 349/67, 349/61, 349/112, 349/113
• US Class Current: 359/599
• CPC Class Codes: G02B 5/021 the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures
• CPC Class Codes: G02B 5/0215 the surface having a regular structure
• CPC Class Codes: G02B 5/0236 the diffusion taking place within the volume of the element
• CPC Class Codes: G02B 5/0257 creating an anisotropic diffusion characteristic, i.e. distributing output differently in two perpendicular axes
• CPC Class Codes: G02B 5/0263 with positional variation of the diffusing properties, e.g. gradient or patterned diffuser
• CPC Class Codes: G02B 5/045 Prism arrays
• 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 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects

Abstract

Plural diffusion patterns are formed on a light-incident surface of an optical film, while plural prisms are formed on a light-emitting surface. The diffusion patterns have, in at least one section thereof, a main inclined surface that is curved face with a relatively small inclination and an auxiliary inclined surface that is oppositely inclined to the main inclined surface with a relatively large inclination.

Claims

1. An optical film comprising:

plural diffusion patterns formed on a light-incident surface, the light-incident surface being the bottom surface of the optical film, and

plural prisms formed on a light-emitting surface, the light-emitting surface being the top surface of the optical film, wherein

each of the diffusion patterns has, in at least one section thereof, a first inclined surface and a second inclined surface,

the first inclined surface being curved and

the second inclined surface being oppositely inclined to the first inclined surface, wherein

incident light hitting the first inclined surface is diffused by the first inclined surface, passed through the optical film, and emitted from the prisms, and

incident light hitting the second inclined surface is reflected by the prisms, and emitted from the bottom surface of the optical film.

2. The optical film according to claim 1, wherein an angle of inclination of the first inclined surface is gradually changed from the lowermost point to the uppermost point.

3. The optical film according to claim 1, wherein a formula of

5°

≦

α

≦

30°

is established wherein an angle of inclination of a segment line connecting the lowermost point to the uppermost point is defined as α

.

4. The optical film according to claim 1, wherein formulae of

θ

max−

α

≦

10°

α

−

θ

min≦

10°

are established wherein an angle of inclination of a segment line connecting the lowermost point to the uppermost point is defined as α

, the maximum angle of inclination of the first inclined surface is defined as θ

max, and the minimum angle of inclination of the first inclined surface is defined as θ

min.

5. The optical film according to claim 1, wherein an angle of inclination of the second inclined surface is approximately 70°

.

6. The optical film according to claim 1, wherein a boundary area between the first inclined surface and the second inclined surface is formed smooth and curved.

7. The optical film according to claim 1, wherein the prisms are randomly formed in size and position.

8. The optical film according to claim 7, wherein each of the prisms is arranged such that its axial direction is directed toward two or more directions.

9. The optical film according to claim 1, wherein the diffusion patterns are randomly formed in size and random position.

10. The optical film according to claim 9, wherein each of the diffusion patterns has substantially the same shape to one another.

11. A surface light source device comprising a light source, a light guide plate that confines light from the light source for transmitting the same and emits the light from a light-emitting surface, and an optical film according to claim 1 arranged so as to face the light-emitting surface of the light guide plate.

12. A liquid crystal display comprising a light source, a light guide plate that confines light from the light source for transmitting the same and emits the light from a light-emitting surface, an optical film according to claim 1 arranged so as to face the light-emitting surface of the light guide plate, and a liquid crystal display panel.