PLANAR ILLUMINATION DEVICE AND LIQUID CRYSTAL DISPLAY DEVICE ADOPTING THE SAME

• US 20090190070A1
• Filed: 07/23/2007
• Published: 07/30/2009
• Est. Priority Date: 07/24/2006
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Kadowaki, Shinichi, Itoh, Tatsuo, Yamamoto, Kazuhisa, Nagata, Takayuki
• Granted Patent: US 8,317,386 B2
• Time in Patent Office: Days
• US Class Current: 349/65
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 6/003 Lens or lenticular sheet or layer
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources

Abstract

A planar illumination device includes a laser light source; a light guide plate for guiding light entered through an end surface to be outputted from a first principal surface; an optical element which forms diffusing light outputted from the laser light source into a substantially parallel light in a thickness-wise direction of the light guide plate and which outputs the resulting parallel light to the end surface of the light guide plate; and a first light deflecting unit for deflecting a propagation direction in the light guide plate of the light incident thereon, wherein the first light deflecting unit is arranged such that a degree of deflection of the light incident on the light guide plate differs according to positions in the light guide plate, to make an amount of light outputted from the first principal surface uniform in the first principal surface.

Claims

1-20. -20. (canceled)

21. A planar illumination device, comprising:

a laser light source for emitting a laser light;

a light guide plate for guiding said laser light entered through a light incident end surface to be outputted from a first principal surface;

an optical element which forms said laser light into a substantially parallel light in a thickness-wise direction of the light guide plate;

a light diffusing unit which diffuses the laser light in a direction orthogonal to the thickness-wise direction of the light guide plate; and

a light deflecting unit which deflects the laser light having passed through said optical element and the diffusing element in the thickness-wise direction of the light guide plate,

wherein said light deflecting unit deflects the laser light in the thickness-wise direction of the light guide plate, after being shaped in the direction of the light incident end surface of the light guide plate by the optical element and the diffusing element.

22. A planar illumination device according to claim 21, wherein:

said light deflecting unit includes a cylindrical lens having a curvature in the thickness-wise direction of the light guide plate, which is provided in vicinity of the light incident end surface of the light guide plate, and which deflects the light incident on the light guide plate in the thickness wise direction of the guiding plate.

23. A planar illumination device according to claim 21, wherein:

said light deflecting unit includes a plurality of deflectors arranged on the first principal surface of the light guide plate or a second principal surface thereof facing the first principal surface;

said plurality of deflectors deflect the laser light incident on the light guide plate in the thickness-wise direction of the light guide plate using an optical phenomenon of at least one of reflection, scattering, refraction and diffraction; and

said plurality of deflectors are provided at higher density in vicinity of the light incident end surface of the light guide plate than that of other portions.

24. A planar illumination device according to claim 22, wherein:

said light deflecting unit includes convexo-concave portions formed on the light incident end surface of the light guide plate, which deflect the laser light incident on the light guide plate in the thickness-wise direction of the light guide plate.

25. A planar illumination device according to claim 22, wherein:

said light deflecting unit includes scattering elements dispersed in the light guide plate at higher density in vicinity of light incident end surface than that of other portions; and

said scattering elements deflect the laser light incident on the light guide plate in the thickness-wise direction of the light guide plate.

26. A planar illumination device according to claim 21, further comprising:

a translucent film formed on the first principal surface of the light guide plate for transmitting the light entered through the first principal surface,

wherein the transmittance of the translucent film is higher in vicinity of the light incident end surface of the light guide plate than that of other portions thereof.

27. A planar illumination device according to claim 23, wherein:

said deflectors include reflective scattering elements.

28. A planar illumination device according to claim 23, wherein:

said deflectors include convexo-concave portions.

29. A planar illumination device according to claim 28, further comprising:

an optical lens provided between the light diffusing unit and the light guide plate, for forming the laser light outputted from the light diffusing unit into a substantially parallel light in a direction orthogonal to the thickness-wise direction of the light guide plate; and

said plurality of deflectors are provided along a plurality of straight lines vertical to the substantially parallel light.

30. A planar illumination device according to claim 28, wherein:

the substantially parallel light outputted from the optical element is incident on the light guide plate in a radial fashion; and

said plurality of deflectors are arranged in parabolas convex in an incident direction of the laser light incident on the light guide plate in the radial fashion.

31. A planar illumination device according to claim 24, wherein said convexo-concave portions form the laser light incident on the light guide plate into a substantially parallel beam in a direction orthogonal to the thickness-wise direction of the light guide plate.

32. A planar illumination device according to claim 24, wherein:

the plurality of convexo-concave portions have a sawtooth shape with an inclined surface forming a Brewster angle with respect to the substantially parallel light outputted form the optical element.

33. A planar illumination device according to claim 21, further comprising:

said laser light is incident onto the light guide plate in a direction inclined with respect to the first principal surface of the light guide plate.

34. A planar illumination device according to claim 21, wherein:

the light incident end surface of the light guide plate is inclined with respect to the first principal surface of the light guide plate.

35. A planar illumination device according to claim 33, wherein:

the light incident end surface of the light guide plate forms a Brewster angle with respect to an incident direction of the laser light incident on the light incident end surface of the light guide plate.

40. A liquid crystal display device, comprising:

a liquid crystal display panel; and

said planar illumination device of claim 21 for illuminating the liquid crystal display panel.

36. A planar illumination device, comprising:

a laser light source for emitting a laser light;

a light guide plate for guiding said laser light entered through a light incident end surface to be outputted from a first principal surface;

an optical element which forms said laser light into a substantially parallel light in a thickness-wise direction of the light guide plate; and

a light diffusing unit which diffuses the laser light in a direction orthogonal to the thickness-wise direction of the light guide plate,

wherein the light guide plate includes a reflecting surface facing the light incident end surface of the light guide plate, which reflects the substantially parallel light incident through the light incident end surface toward the light incident end surface of the light guide plate, and which forms the light reflected therefrom to the light incident end surface into a substantially parallel light in a direction orthogonal to the thickness-wise direction of the light guide plate; and

a light deflecting unit is provided in vicinity of the reflective surface, for diffusing in the light guide plate, the laser light substantially parallel to the thickness-wise direction of the light guide plate in the thickness-wise direction.

37. A planar illumination device according to claim 36, wherein:

said light deflecting unit includes a plurality of deflectors arranged on the first principal surface of the light guide plate or a second principal surface thereof facing the first principal surface;

said plurality of deflectors deflects the laser light incident on the light guide plate in the thickness-wise direction of the light guide plate using an optical phenomenon of at least one of reflection, scattering, refraction and diffraction; and

said plurality of deflectors are provided at higher density in vicinity of the reflecting surface than other portions.

38. A planar illumination device according to claim 36, wherein:

said light deflecting unit includes convexo-concave portions formed on the light incident end surface of the light guide plate, which deflect the laser light entered through the light incident end surface of the light guide plate in the thickness-wise direction of the light guide plate.

39. A planar illumination device according to claim 36, wherein:

said laser light is incident on the light guide plate in a direction inclined with respect to the first principal surface of the light guide plate.