Optical element, lighting device, and liquid crystal display device

• US 20070291369A1
• Filed: 06/19/2007
• Published: 12/20/2007
• Est. Priority Date: 06/19/2006
• Status: Abandoned Application

• Current Assignee: Citizen Electronics Company Limited
• Original Assignee: Citizen Electronics Company Limited
• Inventors: Shimura, Takashi
• Application Number:
  US11/820,343
• Publication Number:
  US 20070291369A1
• Time in Patent Office: Days
• US Class Current: 359/619
• CPC Class Codes: G02B 3/0043 Inhomogeneous or irregular arrays, e.g. varying shape, size, height
• CPC Class Codes: G02B 3/005 arranged along a single direction only, e.g. lenticular sheets G02B3/0043 takes precedence
• CPC Class Codes: G02B 3/0068 arranged in a single integral body or plate, e.g. laminates or hybrid structures with other optical elements G02B5/1885, G02B17/002, G02B30/27 take precedence
• 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

Abstract

A light-diffusing member made of an optically transparent material has a light-emitting surface that emits light while diffusing it. The light-emitting surface has a plurality of parallel elongated lens surfaces arranged side-by-side in a row thereon. The elongated lens surfaces each have a convexly arcuate cross-section. The height of the convexly arcuate cross-section of the elongated lens surfaces varies continuously and repeatedly in the longitudinal direction of the elongated lens surfaces.

Claims

1. An optical element having a light-emitting surface that emits light while diffusing it, said light-emitting surface having a plurality of parallel elongated lens surfaces arranged side-by-side in a row thereon, said elongated lens surfaces each having an arcuate cross-section, wherein a height of said arcuate cross-section of said elongated lens surfaces varies continuously and repeatedly in a longitudinal direction of said elongated lens surfaces.

2. An optical element according to claim 1, wherein the height of the cross-section of each of said elongated lens surfaces varies sinusoidally in the longitudinal direction of said lens surface.

3. An optical element according to claim 2, wherein sinusoidal waves formed by each adjacent pair of said elongated lens surfaces differ from each other in at least one of phase, period, and amplitude.

4. An optical element according to claim 3, which has an opposite surface opposite to said light-emitting surface and has a sheet shape as a whole.

5. An optical element according to claim 4, wherein said opposite surface has a plurality of parallel second elongated lens surfaces arranged side-by-side in a row on said opposite surface, said second elongated lens surfaces each having an arcuate cross-section and extending in a direction perpendicular to the longitudinal direction of the elongated lens surfaces on said light-emitting surface, wherein a height of said arcuate cross-section of said second elongated lens surfaces varies continuously and repeatedly in a longitudinal direction of said second elongated lens surfaces.

6. An optical element according to any of claim 1, wherein the cross-section of each of said elongated lens surfaces is convexly or concavely arcuate.

7. A lighting device using the optical element according to claim 1.

8. A lighting device according to claim 7, which has a light guide plate having a light-emitting surface, wherein said optical element is disposed to oppose to the light-emitting surface of said light guide plate in parallel thereto.

9. A lighting device according to claim 8, wherein said light guide plate and said optical element are integrally molded together.

10. A liquid crystal display device having the lighting device according to claim 9.

11. An apparatus having the liquid crystal display device according to claim 10.