Light source device, display device, terminal device, and optical member

• US 20060227569A1
• Filed: 03/27/2006
• Published: 10/12/2006
• Est. Priority Date: 03/28/2005
• Status: Active Grant

• Current Assignee: NLT Technologies, Ltd.
• Original Assignee: NEC Corporation
• Inventors: Uehara, Shinichi, Imai, Masao
• Granted Patent: US 7,621,665 B2
• Time in Patent Office: Days
• US Class Current: 362/561
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02F 1/1323 Arrangements for providing a switchable viewing angle
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members

Abstract

In the display device, a light source unit, a louver, a transparent/scattering state switching element, and a transmissive liquid crystal panel are provided in sequence, an optical waveguide and a cone sheet are provided to the light source unit, and a light source is disposed on the side of the optical waveguide. The light-exiting surface of the optical waveguide is made flat, and a tilted surface that is tilted to the side of the light source with respect to the light-exiting surface is formed in a light diffusing surface. A flat plate is provided to the cone sheet, and a plurality of circular cones are arranged two-dimensionally on the light-incident surface of the flat plate. The central axes of the circular cones are parallel to each other. The transparent/scattering state switching element is capable of switching between a state for transmitting incident light and a state for scattering the light. By this configuration, a light source device is obtained having high directivity, high luminance, and no limitations on the mounting position of the light source.

Claims

1. A light source device comprising:

a light source;

a light guiding member for emitting the light incident from the light source in a first direction that is different from the incidence direction of the light;

an optical member for emitting the light incident from the light guiding member in a second direction that is different from said first direction;

a light-direction regulating element for regulating the direction of the light incident from the optical member, and emitting the light; and

a transparent/scattering state switching element capable of switching between a state of transmitting the light incident from the light-direction regulating element, and a state of scattering the light;

wherein

said light source is disposed along the light-incident surface of said light guiding member;

said optical member has a plurality of optical elements in a two-dimensional arrangement on the light-incident surface thereof; and

the incident light is emitted with increased directivity in the direction orthogonal to the plane that includes said incidence direction and said first direction.

2. The light source device according to claim 1, wherein

said optical member has a flat plate composed of a transparent material;

said optical elements are formed on said flat plate and comprise a plurality of circular cones formed from a transparent material;

said circular cones are formed on the surface of said flat plate facing said light guiding member; and

the central axes thereof are parallel to each other.

3. The light source device according to claim 2, wherein the phase of one row that comprises the apex points of said circular cones in said optical member differs from the phase of the other rows.

4. The light source device according to claim 2, wherein the direction of the imaginary straight line linking the apex points of said circular cones is parallel to the surface of said flat plate, and comprises three mutually different directions.

5. The light source device according to claim 2, wherein the central axes of said circular cones are tilted with respect to the direction perpendicular to the surface of said flat plate so that said second direction is perpendicular to the surface of said flat plate.

6. The light source device according to claim 2, wherein a diffusion pattern for diffusing the transmitted light is formed on the surface of the side on which said circular cones are not formed in said flat plate.

7. The light source device according to claim 1, wherein

said light source comprises a point light source;

and

a diffusion pattern for diffusing the light is formed on the surface of said light guiding member on which light from said point light source is incident.

8. The light source device according to claim 1, wherein

said light guiding member comprises an optical waveguide on which said light is incident from the side surface thereof, and

a tilted surface that is tilted to the side of said light source with respect to said light-emitting surface is formed on the surface of the opposite side of the light-emitting surface facing said optical member in the optical waveguide.

9. The light source device according to claim 8, wherein said light source is disposed along the side surface of said optical waveguide.

10. The light source device according to claim 1, comprising a reflecting sheet disposed on the side opposite from the side on which said optical member is disposed as viewed from said light guiding member.

11. The light source device according to claim 1, wherein

transparent areas for transmitting said light and absorbent areas for absorbing said light are arranged in alternating fashion along the direction that intersects the incident direction of the light in said light-direction regulating element;

and

said light-direction regulating element regulates the angle range of light in said arrangement direction.

12. The light source device according to claim 11, wherein said light-direction regulating element has first and second layers layered on each other so that the arrangement direction of said transparent areas and absorbent areas in said first layer is orthogonal to the arrangement direction of said transparent areas and absorbent areas in said second layer.

13. The light source device according to claim 1, wherein said transparent areas for transmitting light are arranged in a matrix in said absorbent areas for absorbing light as viewed from said incidence direction of the light in said light-direction regulating element.

14. The light source device according to claim 13, wherein the shape of said transparent areas is circular, elliptical, square, or rectangular as viewed from said incidence direction of the light.

15. The light source device according to claim 11, wherein the boundaries between said transparent areas and said absorbent areas are parallel to said second direction.

16. The light source device according to claim 11, wherein the arrangement direction of said transparent areas is tilted with respect to the arrangement direction of said optical element.

17. The light source device according to claim 1, wherein said light-direction regulating element is integrally formed with said optical member.

18. The light source device according to claim 1, wherein the light source is disposed along the light-incident surface of said light guiding member.

19. The light source device according to claim 1, wherein the light source disposed along the light-incident surface of said light guiding member is a cold cathode tube.

20. A display device comprising:

the light source according to claim 1;

and

a display panel for associating an image with the light by transmitting the light emitted from the light source.

21. The display device according to claim 20, wherein the pixel arrangement direction of said display panel is tilted with respect to the arrangement direction of said optical element.

22. The display device according to claim 20, wherein said display panel is a liquid crystal panel.

23. The display device according to claim 22, wherein said liquid crystal panel operates on a lateral field principle, a multi-domain vertical alignment principle, or a film-compensated TN principle.

24. A terminal device comprising the display device according to claim 20.

25. The terminal device according to claim 24, comprising a mobile telephone, a personal information terminal, a gaming device, a digital camera, a video camera, a video player, a notebook-type personal computer, a cash dispenser, or a vending machine.

26. The terminal device according to claim 25 comprising a mobile telephone, wherein said light source is disposed on the top side or bottom side of the display screen.

27. An optical member comprising:

a light-direction regulating element for regulating the direction of incident light and emitting the light; and

a plurality of circular cones composed of a transparent material integrally formed on said light-direction regulating element.

28. The optical member according to claim 27, wherein the phase of one row that comprises the apex points of said circular cones differs from the phase of the other rows.

29. The optical member according to claim 27, wherein the direction of the imaginary straight line linking the apex points of said circular cones is parallel to the surface of said light-direction regulating element, and comprises three mutually different directions.

30. The optical member according to claim 27, wherein the central axes of said circular cones are tilted with respect to the direction perpendicular to the surface of said light-direction regulating element.

31. The optical member according to claim 27, wherein said light-ray regulation direction in said light-direction regulating element is tilted with respect to the direction of the line normal to the light-incident surface.