Lighting panel having light-collecting function and display device using same

• US 6,827,460 B2
• Filed: 07/29/2002
• Issued: 12/07/2004
• Est. Priority Date: 08/03/2001
• Status: Expired due to Term

• Current Assignee: Ortus Technology Co., Ltd. (TOPPAN Holdings, Inc.)
• Original Assignee: Casio Computer Company Limited
• Inventors: Higuchi, Masaru
• Primary Examiner(s): Lee, Y My Quach
• Application Number:
  US10/207,163
• Publication Number:
  US 20030026108A1
• Time in Patent Office: 862 Days
• Field of Search: 362/26, 362/31, 362/327, 362/328, 362/330, 362/338, 349/63, 349/65
• US Class Current: 362/609
• 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 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer

Abstract

A light-guiding plate has an incidence surface, an end surface formed on the side opposed to the incidence surface, and an optical surface having a surface opposed to the emission surface. The optical surface is constituted by a large number of continuous optical elements, each optical element having a curved surface which refracts part of light introduced from the incidence surface toward the end surface at a low angle along a plane parallel to the emission surface, and an inclined surface which refracts part of light refracted by the curved surface toward the emission surface.

Claims

1. A lighting panel comprising:

a light source; and

a light guiding plate comprising;

an incidence surface on which light emitted from said light source is incident,

an end surface formed on a side of said light guiding plate opposed to said incidence surface,

an emission surface which emits light introduced from said incidence surface, and

an optical surface having a surface opposed to said emission surface;

wherein said optical surface includes a large number of continuous optical elements, and each optical element includes (i) a curved surface which refracts part of light introduced from said incidence surface toward said end surface at a low angle along a surface parallel to said emission surface, and (ii) an inclined surface which refracts part of light refracted by said curved surface toward said emission surface.

2. The lighting panel according to claim 1, wherein said curved surface of each optical element has a curve which drops gradually from a side of said optical surface adjacent to said incidence surface toward a side of said optical surface adjacent to said end surface.

3. The lighting panel according to claim 2, wherein said curved surface of each optical element includes a circular arc shaped section.

4. The lighting panel according to claim 1, wherein each of said optical elements includes a flat surface between said curved surface and said inclined surface.

5. The lighting panel according to claim 4, wherein a height of the inclined surface of an n-th optical element counted from a side of said optical surface adjacent to said incidence surface, relative to said flat surface is

6. The lighting panel according to claim 4, wherein an inclination angle of the inclined surface of each of said optical elements relative to said flat surface is approximately 40 to 50°

.

7. The lighting panel according to claim 4, wherein an inclination angle of the inclined surface of each of said optical elements relative to said flat surface is larger on a side of said optical surface adjacent to said incidence surface than on a side of said optical surface adjacent to said end surface.

8. The lighting panel according to claim 1, wherein a height of said inclined surface of each of said optical elements is smaller in positions on a side of said optical surface adjacent to said incidence surface than in positions on a side of said optical surface adjacent to said end surface.

9. The lighting panel according to claim 1, wherein a thickness of the end surface is smaller than a thickness of said incidence surface and a portion of maximum thickness of said light guiding plate is present between said incidence surface and said end surface.

10. The lighting panel according to claim 1, wherein lengths of said optical elements are substantially the same.

11. The lighting panel according to claim 1, wherein a length of each of said optical elements is smaller on a side of said optical surface adjacent to said end surface than on a side of said optical surface adjacent to said incidence surface.

12. The lighting panel according to claim 1, wherein a length of each of said optical elements is in a range of 20 to 500 μ

m.

13. The lighting panel according to claim 1, wherein a radius of curvature of said curved surface is in a range of 0.1 to 2.0 mm.

14. The lighting panel according to claim 1, further comprising a reflecting layer provided on a rear surface of said light guiding plate.

15. The lighting panel according to claim 1, further comprising an optical sheet disposed on a side of the emission surface of said light guiding plate,

wherein said optical sheet includes a first region for transmitting, without any refraction, light emitted from the emission surface of said light guiding plate in a direction substantially perpendicular to said emission surface and a second region for converting light emitted in a slant direction from the emission surface of said light guiding plate toward the end surface of said light guiding plate into light to be emitted from a front surface of said optical sheet in a direction substantially perpendicular to the emission surface of said light guiding plate.

16. The lighting panel according to claim 15, further comprising a light-collecting sheet disposed on one of (i) a side of the front surface of said optical sheet and (ii) between said light guiding plate and said optical sheet,

wherein said light-collecting sheet converts light emitted in a slant direction from the emission surface of said light guiding plate in a plane parallel to the incidence surface of said light guiding plate into light to be emitted from a front surface of said light-collecting sheet in a direction substantially perpendicular to the emission surface of said light guiding plate.

17. A display device comprising:

a display panel having a front surface on which display images are adapted to be visually recognized and a rear surface opposed to the front surface; and

a lighting panel disposed on a side of one of the front surface and the rear surface of said display panel;

said lighting panel including;

a light source; and

a light guiding plate comprising (i) an incidence surface on which light coming from said light source is incident, (ii) an end surface formed on a side of said light guiding plate opposed to said incidence surface, (iii) an emission surface which emits light introduced from said incidence surface, and (iv) an optical surface having a surface opposed to said emission surface;

wherein said optical surface includes a large number of continuous optical elements, and each optical element includes (i) a curved surface which refracts part of light introduced from said incidence surface toward said end surface at a low angle along a surface parallel to said emission surface, and (ii) an inclined surface which refracts part of light refracted by said curved surface toward the emission surface.

18. The display device according to claim 17, wherein said curved surface of each optical element includes a curve which drops gradually from a side of said optical surface adjacent to said incidence surface toward a side of said optical surface adjacent to said end surface.

19. The display device according to claim 17, wherein said curved surface of each optical element includes a circular arc shaped section.

20. The display device according to claim 17, wherein each of said optical elements includes a flat surface between said curved surface and said inclined surface.

21. The display device according to claim 20, wherein a height of the inclined surface of an n-th optical element counted from a side of said optical surface adjacent to said incidence surface, relative to said flat surface is

22. The display device according to claim 20, wherein an inclination angle of the inclined surface of each of said optical elements relative to said flat surface is approximately 40 to 50°

.

23. The display device according to claim 20, wherein an inclination angle of the inclined surface of each of said optical elements relative to said flat surface is larger on a side of said optical surface adjacent to said incidence surface than on a side of said optical surface adjacent to said end surface.

24. The display device according to claim 17, wherein a height of the inclined surface of each of said optical elements is smaller in positions on a side of said optical surface adjacent to said incidence surface than in positions on a side of said optical surface adjacent to said end surface.

25. The display device according to claim 17, wherein a thickness of said end surface is smaller than the thickness of said incidence surface and a portion of maximum thickness of said light guiding plate is present between said incidence surface and said end surface.

26. The display device according to claim 17, wherein lengths of said optical elements are substantially the same.

27. The display device according to claim 17, wherein a length of each of said optical elements is smaller on a side of said optical surface adjacent to said end surface than on a side of said optical surface adjacent to said incidence surface.

28. The display device according to claim 17, wherein a length of each of said optical elements is in the range of 20 to 500 μ

m.

29. The display device according to claim 17, wherein a radius of curvature of said curved surface is in the range of 0.1 to 2.0 mm.

30. The display device according to claim 17, wherein a reflecting layer is provided on a rear surface of said light guiding plate.

31. The display device according to claim 17, wherein said lighting panel further comprises an optical sheet disposed on a side of the emission surface of said light guiding plate,

wherein said optical sheet includes (i) a first region for transmitting, without any refraction, light emitted from the emission surface of said light guiding plate in a direction substantially perpendicular to said emission surface and, (ii) a second region for converting light emitted in a slant direction from the emission surface of said light guiding plate toward the end surface of said light guiding plate into light to be emitted from a front surface of said optical sheet in a direction substantially perpendicular to the emission surface of said light guiding plate.

32. The display device according to claim 31, wherein said lighting panel further comprises a light-collecting sheet disposed on one of (i) a side of the front surface of said optical sheet and (ii) between said light guiding plate and said optical sheet,

wherein said light-collecting sheet converts light emitted in a slant direction from the emission surface of said light guiding plate in a plane parallel to the incidence surface of said light guiding plate into light to be emitted from a front surface of said light-collecting sheet in a direction substantially perpendicular to the emission surface of said light guiding plate.