LIGHTING DEVICE, DISPLAY DEVICE AND TELEVISION DEVICE

• US 20140375897A1
• Filed: 02/08/2013
• Published: 12/25/2014
• Est. Priority Date: 02/17/2012
• 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: Sugiura, Yasutaka
• Granted Patent: US 9,322,976 B2
• Time in Patent Office: Days
• US Class Current: 348/739
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• 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: G02B 6/0085 Means for removing heat created by the light source from the package heat extraction or cooling elements for semiconductor light sources in general H01L33/64

Abstract

A backlight 12 includes a first LED board 18A, a second LED board 18B 18B, a light guide plate 19, a first LED drive circuit 26a, a second LED drive circuit 26b, and light reflection portions 28. The second LED board 18B is arranged in a high temperature area in which a temperature tends to become higher. The light guide plate 19 includes a pair of end surfaces opposite the first LED board 18A and the second LED board 18B, respectively, and through which rays of light from the first LED board 18A and the second LED board 18B enter, and a plate surface through which rays of light exit on a light exiting side. The first LED drive circuit 26a and the second LED drive circuit 26b are configured to supply a smaller current to the second LED board 18B than the current supplied to the first LED board 18A. The light reflection portions 28 are arranged such that an area distribution in a plane of the plate surface of the light guide plate 19 increases as a distance from one of the first LED board 18A and the second LED board 18B increases and takes the maximum value at a point closer to the second LED board 18B.

Claims

1. A lighting device comprising:

a first light source;

a second light source opposed to the first light source and arranged in a high temperature area in which a temperature tends to become higher than an area in which the first light source is arranged;

a light guide plate arranged between the first light source and the second light source and configured such that rays of light from the first light source and the second light source enter through end surfaces opposite the first light source and the second light source, respectively, and exit through a plate surface on a light exiting side;

a light source driver configured to drive the first light source and the second light source to supply a smaller current to the second light source than a current supplied to the first light source; and

light reflection portions configured to reflect rays of light in the light guide plate to the light exiting side to increase rays of light exiting from the plate surface of the light guide plate on the light exiting side and arranged such that an area distribution in a plane of the plate surface of the light guide plate increases as a distance from corresponding one of the first light source and the second light source increases and takes a maximum value at a point closer to the second light source.

2. The lighting device according to claim 1, wherein the first light source and the second light source include unit light sources arranged in a line along the end surfaces of the light guide plate, respectively, and a number and intervals of the unit light sources along one of the end surfaces are equal to those of the unit light sources along the other one of the end surfaces.

3. The lighting device according to claim 1 or 2, wherein the area of the light reflection portions in an edge area of the light guide plate closer to the first light source is smaller than the area of the light reflection portions in an edge area of the light guide plate closer to the second light source.

4. The lighting device according to claim 1, wherein the light reflection positions include a number of dots dispersedly arranged on a plate surface of the light guide plate opposite from the plate surface on the light exiting side.

5. The lighting device according to claim 1, wherein the light reflection portions are arranged such that a ratio of a distance from the point at which the area of the light reflection portions in the plane of the plate surface of the light guide plate is the maximum to the first light source to a distance from the point at which the area of the light reflection portions is the maximum to the second light source is about equal to a ratio of the current supplied to the first light source by the light source drive circuit to the current supplied to the second light source by the light source drive circuit.

6. The lighting device according to claim 1, wherein the light reflection portions area arranged such that a ratio of a distance from the point at which the area of the light reflection portions in the plane of the plate surface of the light guide plate is the maximum to the first light source to a distance from the point at which the area of the light reflection portions is the maximum to the second light source is about equal to a ratio of a brightness level of emitted light from the first light source to a brightness level of emitted light from the second light source.

7. The lighting device according to claim 1, wherein a distance between the first light source and one of the end surfaces of the light guide plate is larger than a distance between the second light source and the other one of the end surfaces of the light guide plate.

8. The lighting device according to claim 1, further comprising:

a chassis holding the first light source, the second light source, and the light guide plate therein; and

a light source drive circuit board including a light source drive section, mounted to the chassis on an opposite side from the light exiting side, and arranged closer to the second light source.

9. A display device comprising:

the lighting device according to claim 1; and

a display panel configured to provide a display using light from the lighting device.

10. The display device according to claim 9, further comprising a panel driver connected to the display panel, configured to drive the display panel, and arranged closer to the second light source.

11. The display device according to claim 9, wherein

the lighting device comprises a chassis holding the first light source, the second light source, and the light guide plate therein, the display device,

the display device comprises:

a panel driver connected to the display panel and configured to drive the display panel; and

a panel drive control circuit board connected to the panel driver, configured to control driving of the panel driver, mounted to the chassis on an opposite side from the light exiting side, and arranged closer to the second light source.

12. The display device according to claim 9, wherein the display panel is a liquid crystal panel including a pair of substrates and liquid crystals sealed between the substrates.

13. A television device comprising the display device according to claim 9.