Lighting device with light-scattering optical member

• US 8,794,780 B2
• Filed: 10/09/2009
• Issued: 08/05/2014
• Est. Priority Date: 01/23/2009
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Ikuta, Kaori
• Primary Examiner(s): Negron, Ismael
• Application Number:
  US13/145,347
• Publication Number:
  US 20110285922A1
• Time in Patent Office: 1,761 Days
• Field of Search: 362/97.2, 362/339, 362/97.4, 362/222, 362/223, 362/224, 362/217.02, 362/311.01, 362/311.14, 362/311.15, 362/326, 362/327, 362/330, 362/331, 362/333, 349/68
• US Class Current: 362/97.4
• CPC Class Codes: G02B 5/0226 having particles on the surface
• CPC Class Codes: G02B 5/0263 with positional variation of the diffusing properties, e.g. gradient or patterned diffuser
• CPC Class Codes: G02F 1/133604 with lamps
• CPC Class Codes: G02F 1/133605 including specially adapted reflectors
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/133611 including means for improving the brightness uniformity

Abstract

A backlight device 12 includes cold cathode tubes 17, a chassis that houses the cold cathode tubes 17 therein and having an opening 14b through which light emitted from the cold cathode tubes exits, and a diffuser plate 15 provided so as to face the cold cathode tubes 17 and cover the opening 14b. A light reflecting portion 30 is formed on a side of the diffuser plate 15 close to the cold cathode tubes 17 so as to have different light reflectance in every surface area of a surface of the diffuser plate 15. A scattering structure 31 is formed on a side of the diffuser plate 15 opposite from the cold cathode tubes 17 and scatters the light.

Claims

1. A lighting device, comprising:

a light source;

a chassis configured to house the light source therein and having an opening through which light emitted from the light source exits;

an optical member provided so as to face the light source and cover the opening and having a surface including surface areas;

a light reflecting portion provided on a side of the optical member close to the light source and configured to have different light reflectance in each of the surface areas; and

a scattering structure formed on a side of the optical member opposite from the light source and configured to scatter the light;

wherein

the chassis has a surface facing the optical member and the surface including at least a first end portion, a second end portion, and a middle portion, the second end portion being located at an end away from the first end portion, and the middle portion being located between the first end portion and the second end portion;

one or two of the first end portion, the second end portion and the middle portion are configured as light source installation areas in each of which the light source is arranged, and the rest is configured as an empty area in which no light source is arranged;

the light reflecting portion is formed such that a portion of the optical member that overlaps the light source installation area has a light reflectance higher than a portion of the optical member that overlaps the empty area; and

the light reflecting portion has a uniform light reflectance in a portion that overlaps the light source installation area.

2. The lighting device according to claim 1, wherein the light reflecting portion is formed such that the light reflectance of a portion of the optical member that overlaps the empty area decreases in a continuous and gradual manner from a side close to the portion that overlaps the light source installation area to the side away therefrom.

3. A lighting device, comprising:

a light source;

a chassis configured to house the light source therein and having an opening through which light emitted from the light source exits;

an optical member provided so as to face the light source and cover the opening and having a surface including surface areas;

a light reflecting portion provided on a side of the optical member close to the light source and configured to have different light reflectance in each of the surface areas; and

a scattering structure formed on a side of the optical member opposite from the light source and configured to scatter the light;

wherein

the chassis has a surface facing the optical member and the surface including at least a first end portion, a second end portion, and a middle portion, the second end portion being located at an end away from the first end portion, and the middle portion being located between the first end portion and the second end portion;

one or two of the first end portion, the second end portion and the middle portion are configured as light source installation areas in each of which the light source is arranged, and the rest is configured as an empty area in which no light source is arranged;

the light reflecting portion is formed such that a portion of the optical member that overlaps the light source installation area has a light reflectance higher than a portion of the optical member that overlaps the empty area; and

the light reflecting portion is formed such that the light reflectance of a portion of the optical member that overlaps the empty area decreases in a stepwise manner from a side close to the portion that overlaps the light source installation area to the side away therefrom.

4. The lighting device according to claim 3, wherein the light source installation area of the chassis is smaller than the empty area.

5. The lighting device according to claim 3, wherein the light source installation area is provided in the middle portion of the chassis.

6. The lighting device according to claim 3, wherein the light source installation area is provided in one of the first end portion and the second end portion.

7. The lighting device according to claim 3, wherein the light source installation area is provided in each of the first end portion and the second end portion.

8. The lighting device according to claim 3, wherein the light reflecting portion is formed such that the light reflectance of a portion of the optical member that overlaps the empty area is higher on a side close to the portion that overlaps the light source installation area than on a side away therefrom.

9. The lighting device according to claim 3, wherein the light reflecting portion is configured by a dot pattern having light reflectivity.

10. The lighting device according to claim 3, wherein the light reflecting portion has a uniform light reflectance in a portion that overlaps the light source installation area.

11. The lighting device according to claim 3, wherein the optical member contains diffuser particles dispersed therein.

12. The lighting device according to claim 11, wherein the light reflecting portion has light reflectance higher than the optical member.

13. A display device comprising:

the lighting device according to claim 3; and

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

14. The display device according to claim 13, wherein the display panel is a liquid crystal display panel using liquid crystal.

15. A television receiver comprising the display device according to claim 13.