Planar light source device and display device using the same

• US 20060262530A1
• Filed: 04/10/2006
• Published: 11/23/2006
• Est. Priority Date: 05/23/2005
• Status: Active Grant

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Sakai, Seiji, Yoneda, Toshiyuki
• Granted Patent: US 7,393,128 B2
• Time in Patent Office: Days
• US Class Current: 362/231
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 47/16 by timing means
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A planar light source device includes a light source section having a plurality of light emitting diodes as a light source, and a light guiding plate guiding light from the light source section to emit planar light. The light emitting diodes being turned off detect the quantities of light from the other light emitting diodes, and adjust the quantities of light emission of the other light emitting diodes based on the detected quantities of light.

Claims

1. A planar light source device comprising:

a light source section having a plurality of light emitting diodes as a light source; and

a light guiding section guiding light from said light source section to emit planar light, wherein

said light emitting diodes being turned off detect the quantities of light from the other said light emitting diodes, and adjust the quantities of light emission of the other said light emitting diodes based on the detected quantities of light.

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

said light emitting diodes repeat a turn-on period and a turn-off period at a predetermined timing.

3. The planar light source device according to claim 1, wherein

said light source section includes a plurality of said light emitting diodes emitting lights of different wavelengths, said light emitting diodes being turned off detecting the quantities of light from the other said light emitting diodes, and adjusting the quantities of light emission of the other said light emitting diodes based on the detected quantities of light with respect to each of said wavelengths.

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

said light source section includes said light emitting diodes emitting light of a monochromatic wavelength of red, blue and green.

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

said light source section further includes said light emitting diodes emitting light of a wavelength longer than said monochromatic wavelength of red.

6. The planar light source device according to claim 5, wherein

said light of a longer wavelength is infrared light.

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

said light source section is divided into at least two light source drive-control blocks, said light emitting diodes emitting light and detecting the quantities of light with respect to each of said light source drive-control blocks.

8. The planar light source device according to claim 7, wherein

said light emitting diodes mounted on one of said light source drive-control blocks detect, upon being turned off, the quantities of light, and adjust the quantities of light emission of said light emitting diodes mounted on another of said light source drive-control blocks based on the detected quantities of light.

9. The planar light source device according to claim 7, wherein

said light emitting diodes repeat a turn-on period and a turn-off period at a predetermined timing with respect to each of said light source drive-control blocks.

10. The planar light source device according to claim 9, wherein

said light emitting diodes repeat said turn-on period and turn-off period overlapping one another for a predetermined period among a plurality of said light source drive-control blocks.

11. A display device comprising:

a planar light source device including;

a light source section having a plurality of light emitting diodes as a light source; and

a light guiding section guiding light from said light source section to emit planar light, wherein

said light emitting diodes being turned off detect the quantities of light from the other said light emitting diodes, and adjust the quantities of light emission of the other said light emitting diodes based on the detected quantities of light, and

a display element arranged on an emission surface side of said planar light source device, for displaying a desired image.

12. The display device according to claim 11, wherein

said display element is a liquid crystal display element.