Illumination device and liquid crystal display device provided therewith

• US 8,018,427 B2
• Filed: 11/02/2006
• Issued: 09/13/2011
• Est. Priority Date: 04/28/2006
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Hamada, Tetsuya
• Primary Examiner(s): Tran; My-Chau T
• Application Number:
  US12/293,635
• Publication Number:
  US 20100231613A1
• Time in Patent Office: 1,776 Days
• Field of Search: 345/55, 345/76, 345/82, 345/84, 345/87, 345/102, 345/204, 345/690, 315/149, 315/158
• US Class Current: 345/102
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133609 including means for improving the color mixing, e.g. white
• CPC Class Codes: G02F 2201/58 Arrangements comprising a monitoring photodetector
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/40 Details of LED load circuits

Abstract

An illumination device includes a light source section with white LEDs on a side of a light guide plate. The white LED includes a first white LED and a second white LED, and they emit light of different chromaticities. In a chromaticity diagram, a white color area is divided into two subareas by a dividing line passing through a target chromaticity; light emitted by the first white LED falls within a first subarea, and light emitted by the second white LED falls within a second subarea. By individually controlling the light emission of the first white LED and the second white LED, it is possible to emanate a desired white light from the light guide plate.

Claims

1. An illumination device comprising:

a plurality of white LEDs; and

a control device arranged to control light emission of the white LEDs;

wherein

a white color area in a chromaticity diagram is divided into a plurality of subareas, white LEDs whose emitted light falls within any one of the subareas are provided and the control device individually controls light emission of the white LEDs whose emitted light falls within the different subareas.

2. The illumination device of claim 1, wherein light emitted by the white LEDs disposed side by side falls within the different subareas.

3. The illumination device of claim 1, further comprising a light guide plate arranged to receive light from a side surface thereof and emanating the light through an emission surface thereof, wherein the white LEDs are disposed on the side surface of the light guide plate in a line.

4. The illumination device of claim 1, wherein the white LEDs are disposed in a plane.

5. The illumination device of claim 1, further comprising a color measuring device measuring color of light emitted by the white LEDs, wherein, based on an output of the color measuring device, the control device controls the light emission of the white LEDs.

6. The illumination device of claim 1, further comprising a temperature measuring device near the white LED, wherein, based on an output of the temperature measuring device, the control device controls the light emission of the white LEDs.

7. A liquid crystal display device comprising:

a liquid crystal panel; and

the illumination device of claim 1 disposed on a back of the liquid crystal panel.