SURFACE LIGHT SOURCE DEVICE AND DISPLAY DEVICE USING THE SAME

• US 20070147073A1
• Filed: 12/12/2006
• Published: 06/28/2007
• Est. Priority Date: 12/15/2005
• Status: Active Grant

• Current Assignee: Trivale Technologies, LLC (Vector Capital Corporation)
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Sakai, Seiji, Yoneda, Toshiyuki
• Granted Patent: US 7,762,705 B2
• Time in Patent Office: Days
• US Class Current: 362/607
• CPC Class Codes: G02B 6/0021 for housing at least a part of the light source, e.g. by forming holes or recesses
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

A surface light source device according to the invention includes a housing having an opening portion on at least one face, an LED light source held by one face of the housing opposing the opening portion, and a light guiding plate arranged at a position so as to cover the opening portion and the LED light source, wherein the light guiding plate includes a recess provided at a position corresponding to the LED light source for storing a part of the LED light source, and light quantity adjusting means provided at a bottom part of the recess for adjusting light from the LED light source, and the light quantity adjusting means includes a reflection sheet having a reflection function and a transmission function in which a total light transmittance t satisfies t≧πr² cos θ/{(1−cos θ)(S−πr²)}, supposing that an average radius is defined as r, a distance from the LED light source is defined as H, a light-emitting area of the LED light source is defined as S, and a total light quantity is defined as L.

Claims

1. A surface light source device comprising:

a housing having an opening portion on at least one face;

a light source held by one face of said housing opposing said opening portion; and

a light guiding plate arranged at a position so as to cover said opening portion and said light source, wherein

said light guiding plate includes;

a recess provided at a position corresponding to said light source for storing a part of said light source; and

light quantity adjusting means provided at a bottom part of said recess for adjusting light from said light source, and

said light quantity adjusting means includes a reflection sheet having a reflection function for reflecting the light from said light source and a transmission function in which a total light transmittance t satisfies t≧

π

r² cos θ

/{(1−

cos θ

)(S−

π

r²)}, supposing that an average radius is defined as r, a distance from said light source is defined as H, a light-emitting area of said light source is defined as S, and a total light quantity of said light source is defined as L.

6. The surface light source device according to claim 1, wherein

said reflection sheet has a diffusion function for diffusing transmitted light.

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

said light quantity adjusting means further includes a diffusion sheet for diffusing light from said light source.

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

said reflection sheet has black printing performed on a surface thereof on a side of said light source.

12. The surface light source device according to claim 1, wherein

said reflection sheet has color printing performed on a surface thereof on a side opposite to said light source.

13. The surface light source device according to claim 8, wherein

said diffusion sheet has black printing performed on a surface thereof on a side of said light source.

14. The surface light source device according to claim 8, wherein

said diffusion sheet has color printing performed on a surface thereof on a side opposite to said light source.

15. The surface light source device according to claim 12, wherein

the color of said printing is blue.

16. The surface light source device according to claim 11, wherein

one of said black printing is dot pattern printing.

17. The surface light source device according to claim 1, wherein

said reflection sheet has a plurality of holes.

18. The surface light source device according to claim 1, wherein

said light source is a light-emitting diode.

19. The surface light source device according to claim 1, wherein

said light source is a while light-emitting diode.

2. A surface light source device comprising:

a housing having an opening portion on at least one face;

a light source held by one face of said housing opposing said opening portion; and

a light guiding plate arranged at a position so as to cover said opening portion and said light source, wherein

said light guiding plate includes;

a recess provided at a position corresponding to said light source for storing a part of said light source; and

light quantity adjusting means provided at a bottom part of said recess for adjusting light from said light source, and

said light quantity adjusting means includes a reflection sheet having a reflection function for reflecting the light from said light source and a transmittance function in which a total light transmittance is at least 2%.

7. The surface light source device according to claim 2, wherein

said reflection sheet has a diffusion function for diffusing transmitted light.

9. The surface light source device according to claim 2, wherein

said light quantity adjusting means further includes a diffusion sheet for diffusing light from said light source.

3. A surface light source device comprising:

a housing having an opening portion on at least one face;

a light source held by one face of the housing opposing said opening portion; and

a light guiding plate arranged at a position so as to cover said opening portion and said light source, wherein

said light guiding plate includes;

a first recess provided at a position corresponding to said light source for storing a part of said light source; and

a second recess provided back-to-back to said first recess, and

the surface light source device further comprises light quantity adjusting means provided at a bottom part of said second recess for adjusting light from said light source.

4. The surface light source device according to claim 3, wherein

said light quantity adjusting means includes a reflection sheet for reflecting the light from said light source.

5. The surface light source device according to claim 4, wherein

said reflection sheet has a reflection function for reflecting the light from said light source and a transmittance function in which a total light transmittance is at least 2%.

10. The surface light source device according to claim 3, wherein

said light quantity adjusting means further includes a diffusion sheet for diffusing light from said light source.

20. A display device comprising:

a surface light source device; and

a display panel arranged above said opening portion of said surface light source device, wherein

the surface light source device includes;

a housing having an opening portion on at least one face;

a light source held by one face of said housing opposing said opening portion; and

a light guiding plate arranged at a position so as to cover said opening portion and said light source,

said light guiding plate includes;

a recess provided at a position corresponding to said light source for storing a part of said light source; and

light quantity adjusting means provided at s bottom part of said recess for adjusting light from said light source, and

said light quantity adjusting means includes a reflection sheet having a reflection function for reflecting the light from said light source and a transmission function in which a total light transmittance t satisfies t≧

π

r² cos θ

/{(1−

cos θ

)(S−

π

r²)}, supposing that an average radius is defined as r, a distance from said light source is defined as H, a light-emitting area of said light source is defined as S, and a total light quantity of said light source is defined as L.