Planar light source device and display device using the same

• US 7,300,184 B2
• Filed: 05/17/2005
• Issued: 11/27/2007
• Est. Priority Date: 06/07/2004
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Ichikawa, Koji, Sakai, Seiji, Yoneda, Toshiyuki
• Primary Examiner(s): O'Shea; Sandra
• Assistant Examiner(s): Dunwiddie; Meghan K.
• Application Number:
  US11/130,255
• Publication Number:
  US 20050270796A1
• Time in Patent Office: 924 Days
• Field of Search: 362/326, 362/331, 362/332, 362/551, 362/555, 362/561, 362/613, 362/620
• US Class Current: 362/331
• CPC Class Codes: G02B 6/001 the light being emitted along at least a portion of the lateral surface of the fibre
• 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 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: G02B 6/2808 using a mixing element which evenly distributes an input signal over a number of outputs
• CPC Class Codes: G02B 6/423 using guiding surfaces for the alignment

Abstract

In a planar light guiding device and a display device, plural light guiding rods are arranged in parallel to one another in a housing having an opening portion serving as a light emission face at the upper surface thereof, and a point light source (LED) 2 is disposed so as to oppose to at least one of both the end faces 1a of each light guiding rod through a space, thereby constituting a light source unit. These light source units are arranged in the metal housing to thereby form the planar light guiding device.

Claims

1. A planar light source device comprising:

a housing having an opening portion in an upper surface thereof;

a plurality of light source units, each including a light guiding rod arranged in the housing and at least one point light source disposed so as to oppose at least one end face of the light guiding rod and emit light to the one end face; and

a reflection plate disposed below the plurality of light source units in the housing and reflects light emitted from the light source units to the opening portion,

wherein each of the light guiding rods has a light emission means for varying a light emission rate in accordance with a distance from the point light source to one end face thereof, the light emission means being an uneven surface whose roughness is varied in accordance with the distance.

2. The planar light source device according to claim 1, wherein at least one of the point light sources is disposed so as to oppose to at least one end face of the light guiding rod through a space.

3. The planar light source device according to claim 1, wherein the plurality of light source units include a plural kinds of the light source units using different kinds of the point light sources that emits different light colors.

4. The planar light source device according to claim 1, wherein the opening portion of the housing is designed in a substantially rectangular shape having long sides and short sides, and the light guiding rods of all light source units are arranged in substantially parallel to the short sides of the opening portion.

5. A display device comprising the planar light source device according to claim 1, and a display unit which is disposed above the opening portion of the planar light source device and modulates light emitted from the planar light source device to display information.

6. A planar light source device comprising:

a housing having an opening portion in an upper surface thereof;

a plurality of light source units, each including a light guiding rod arranged in the housing and at least one point light source disposed so as to oppose to at least one end face of the light guiding rod and emit light to the one end face; and

a reflection plate which is disposed below the plurality of light source units in the housing and reflects light emitted from the light source units to the opening portion,

wherein each of the light guiding rods is designed so that the sectional area thereof in the vertical direction to the longitudinal direction thereof is varied.

7. The planar light source device according to claim 6, wherein at least one of the point light sources is disposed so as to oppose to at least one end face of the light guiding rod through a space.

8. The planar light source device according to claim 6, wherein the plurality of light source units include a plural kinds of the light source units using different kinds of the point light sources that emits different light colors.

9. The planar light source device according to claim 6, wherein the opening portion of the housing is designed in a substantially rectangular shape having long sides and short sides, and the light guiding rods of all light source units are arranged in substantially parallel to the short sides of the opening portion.

10. A display device comprising the planar light source device according to claim 6, and a display unit which is disposed above the opening portion of the planar light source device and modulates light emitted from the planar light source device to display information.

11. A planar light source device comprising:

a housing having an opening portion in an upper surface thereof;

a plurality of light source units, each including a light guiding rod arranged in the housing and at least one point light source disposed so as to oppose at least one end face of the light guiding rod and emit light to the one end face; and

a reflection plate which is disposed below the plurality of light source units in the housing and reflects light emitted from the light source units to the opening portion,

wherein each of the light guiding rods has a light emission means for varying a light emission rate in accordance with a distance from the point light source to the end face thereof, the light emission means is a prism array whose brightness distribution in a longitudinal direction of the light guiding rod is adjusted in accordance with the distance.

12. The planar light source device according to claim 11, wherein at least one of the point light sources is disposed so as to oppose at least one end face of the light guiding rod through a space.

13. The planar light source device according to claim 11, wherein the plurality of light source units include a plural kind of the light source units using different kinds of the point light sources that emits different light colors.

14. The planar light source device according to claim 11, wherein the opening portion of the housing is designed in a substantially rectangular shape having long sides and short sides, and the light guiding rods of all light source units are arranged in substantially parallel to the short sides of the opening portion.

15. A display device comprising the planar light source device according to claim 11, wherein a display unit is disposed above the opening portion of the planar light source device and modulates light emitted from the planar light source device to display information.