Backlight for liquid crystal display device and liquid crystal display device using the same

• US 8,243,232 B2
• Filed: 08/26/2009
• Issued: 08/14/2012
• Est. Priority Date: 08/28/2008
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated), Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Inventors: Yamazaki, Sachiko, Oke, Ryutaro, Imajo, Ikuko
• Primary Examiner(s): Robinson, Mark
• Assistant Examiner(s): CHANG, CHARLES S
• Application Number:
  US12/547,686
• Publication Number:
  US 20100053505A1
• Time in Patent Office: 1,084 Days
• Field of Search: 349/67, 349/61, 362/609
• US Class Current: 349/67
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133605 including specially adapted reflectors

Abstract

An object of the present invention is to provide a backlight for a liquid crystal display device which is easy to repair and prevents the brightness from lowering on the screen, and thus can provide high-quality images, where the region where point light source elements are aligned is divided into a number of smaller regions, and backlight units are provided so as to correspond to the respective smaller regions, as well as a liquid crystal display device using the same. The present invention provides a backlight for a liquid crystal display device where a number of point light source elements 2 are aligned in a plane, having: a number of backlight units, each of which is formed of a support substrate 31, 32 for supporting point light source elements 2 and point light source elements 2 arranged on the support substrate, the region in which the point light source elements are aligned being divided into a number of smaller regions, each of which having a backlight unit; and a reflective sheet provided on the support substrates of the backlight units, having openings created at points where the point light source elements are located, characterized in that the reflective sheet is formed of a number of sheets 41, 42 and covers the entire region.

Claims

1. A backlight for a liquid crystal display device, where a number of point light source elements are aligned in a plane, comprising:

a number of backlight units, each of which is formed of a support substrate for supporting point light source elements and point light source elements arranged on the support substrate, a region in which the point light source elements are aligned being divided into a number of smaller regions, each of which having a backlight unit; and

a reflective sheet provided on the support substrates of the backlight units, having openings created at points where the point light source elements are located, characterized in that

the reflective sheet is formed of a number of sheets and covers the entire region and the reflective sheet is provided over a number of the support substrates of the backlight units and

that a center-to-center distance between each of adjacent point light source elements of adjacent sheets located at adjacent edges of the adjacent sheets is shorter than any center-to-center distance between each of adjacent point light source elements located on the same sheet.

2. The backlight for a liquid crystal display device according to claim 1, characterized in that each sheet that forms the reflective sheet includes at least one smaller region, and that a minimum unit for an area of each sheet is the one smaller region.

3. The backlight for a liquid crystal display device according to claim 2, characterized in that each sheet that forms the reflective sheet has approximately a same area as each of the backlight units.

4. The backlight for a liquid crystal display device according to claim 1, characterized in that the sheets that form the reflective sheet are arranged so as to overlap with each other.

5. The backlight for a liquid crystal display device according to claim 1, characterized in that each of the point light source elements is a light emitting diode.

6. A liquid crystal display device comprising a liquid crystal display panel and a direct backlight for illuminating the liquid crystal display panel, characterized in that

the backlight for a liquid crystal display device according to any one of claims 1 to 5 is used as the backlight.

7. A backlight for a liquid crystal display device according to claim 1, characterized in that a relationship of the center-to-center distance between each of the adjacent pointy light source elements of adjacent sheets with respect to the center-to-center distance between each of adjacent point light source elements of the same sheet enables prevention of lowering of brightness along a border between the adjacent sheets.