Lighting system and display apparatus using the same

• US 7,661,866 B2
• Filed: 07/28/2006
• Issued: 02/16/2010
• Est. Priority Date: 07/29/2005
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated)
• Inventors: Akahoshi, Haruo, Kaneko, Hiroki, Tanaka, Toshiaki, Hiyama, Ikuo
• Primary Examiner(s): Husar; Stephen F.
• Assistant Examiner(s): Neils; Peggy A.
• Application Number:
  US11/494,717
• Publication Number:
  US 20070035969A1
• Time in Patent Office: 1,299 Days
• Field of Search: 362/249, 362/800, 362/555, 362/612, 362/294, 362/373, 362/249.01, 362/249.03, 362/249.02, 257/99
• US Class Current: 362/612
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: H01L 33/642 characterized by the shape

Abstract

The present invention provides a low-cost and highly heat-radiating lighting system and a display apparatus using the same. The lighting system has a plurality of packages, each containing LEDs, lead frames and a transparent sealing material, a heat-radiating substrate and an adhesive layer adapted to bond the packages and the heat-radiating substrate. The lead frames are 0.1 mm or more in thickness. Further, the area of the surfaces of the heat-radiating substrate and the lead frames bonded together via the adhesive layer is 70 mm² per 1 mm² area of the LEDs. The display apparatus of the present invention uses the lighting system as the backlight thereof.

Claims

1. A lighting system comprising:

a heat-radiating substrate;

an adhesive layer disposed on the heat-radiating substrate;

lead frames disposed on the adhesive layer; and

LEDs disposed on and connected to the lead frames so as to delimit a contact area with the lead frames;

wherein a thermal conductivity of the adhesive layer is 1.7 W/m-K or more, and

wherein a ratio of a contact area between the lead frames and the adhesive layer relative to the contact area between the LEDs and the lead frames is 300 or more.

2. The lighting system of claim 1, wherein

the ratio of the areas is 500 or more.

4. The lighting system of claim 1, wherein

a plurality of packages each having the LEDs, the lead frames, and a transparent sealing material are provided, and wherein

the packages and the heat-radiating substrate are bonded together by the adhesive layer.

5. The lighting system of claim 4, wherein

the plurality of packages are electrically connected by the lead frames.

14. A display apparatus comprising:

a backlight having the lighting system of any one of claims 1 to 3 and 6;

a group of optical members adapted to control the uniformity and directivity of the beam from the backlight; and

a non-luminescent display panel made up of a plurality of pixels and adapted to control the reflection or transmission of a beam for each of the pixels.

15. The display apparatus of claim 14, wherein

the backlight has a light-guiding element adapted to allow the beam from the lighting system to enter the backlight from the incidence surface on the side thereof and leave the backlight from the top surface thereof.

16. The display apparatus of claim 15, wherein

the backlight has the plurality of sets of lighting system and light-guiding element, and wherein

the lighting systems and the light-guiding elements are arranged in a tiled fashion.

3. A lighting system comprising:

a heat-radiating substrate;

an adhesive layer disposed on the heat-radiating substrate;

lead frames disposed on the adhesive layer; and

LEDs disposed on and connected to the lead frames so as to delimit a contact area with the lead frames;

wherein a thermal conductivity of the adhesive layer is 5 W/m-K or more, and

wherein a ratio of a contact area between the lead frames and the adhesive layer relative to the contact area between the LEDs and the lead frames is 250 or more.

6. A lighting system comprising a plurality of packages,

wherein each of the plurality of packages includes:

a heat-radiating substrate;

an adhesive layer disposed on the heat-radiating substrate;

lead frames disposed on the adhesive layer; and

LEDs mounted on and connected to the lead frames so as to delimit a contact area with the lead frames;

wherein a thermal conductivity of the adhesive layer is 1.7 W/m-K or more and

wherein a ratio of a contact area between the lead frames and the adhesive layer relative to the contact area between the LEDs and the lead frames is 300 or more,

wherein the LEDs are connected to the lead frames by wire bonding; and

wherein an area of the lead frame on which the LED is mounted is larger than an area of the lead frame on which no LED is mounted; and

wherein the lead frame of one of the packages is electrically connected to a lead frame of an adjacent package by one of soldering, spot welding, ultrasonic welding, mechanical crimping and a wiring formed on the adhesive layer.

7. The lighting system of claim 6, wherein

the adhesive layer is made up of a rigid film with an adhesive film disposed on at least one side of the rigid film.

8. The lighting system of claim 7, wherein

the at least one of the rigid and adhesive film making up the adhesive layer has wiring that is provided between the two or more lighting systems, and wherein

the at least one of the rigid and adhesive film is shared by the two or more lighting systems as a continuous film.

9. The lighting system of claim 7, wherein

a plurality of packages each having the LEDs, the lead frames, and a transparent sealing material are provided;

wherein the rigid film has holes; and

wherein the packages exist in the holes of the rigid film.

10. The lighting system of claim 9, wherein

the lead frames of the plurality of packages or of units composed of the plurality of packages are electrically connected at the same location.

11. The lighting system of claim 10, wherein

the package has a reflector mold.

12. The lighting system of claim 11, wherein

the package contains one or more LEDs emitting a red beam, one or more LEDs emitting a blue beam, and one or more LEDs emitting a green beam.

13. The lighting system of claim 12, wherein

the package contains the LED emitting a red beam, the LED emitting a blue beam, and the two LEDs emitting a green beam, and wherein

the area of the lead frames with the LEDs emitting red and blue beams is larger than that of the lead frames with the LEDs emitting a green beam.