Backlight unit

• US 20070002587A1
• Filed: 06/09/2006
• Published: 01/04/2007
• Est. Priority Date: 06/10/2005
• Status: Active Grant

• Current Assignee: Citizen Electronics Company Limited, Hitachi Chemical Company Limited (Resonac Holdings Corp.)
• Original Assignee: Citizen Electronics Company Limited, Hitachi Chemical Company Limited (Resonac Holdings Corp.)
• Inventors: Miyashita, Junji
• Granted Patent: US 7,703,969 B2
• Time in Patent Office: Days
• US Class Current: 362/618
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer

Abstract

A backlight unit includes a light guide plate having opposite side surfaces and a peripheral edge surface. A part of the peripheral edge surface is a light entrance surface, and one of the opposite side surfaces is a light exit surface. A light source is disposed adjacent to the light entrance surface of the light guide plate. A light deflecting film is disposed adjacent and parallel to the light exit surface of the light guide plate. The light deflecting film has a multilayer construction wherein light reflecting layers and light transmitting layers are stacked one by one alternately. The light reflecting and transmitting layers are tilted at a predetermined angle to the light exit surface.

Claims

1. A backlight unit comprising:

a light guide plate having opposite side surfaces and a peripheral edge surface, wherein a part of said peripheral edge surface is a light entrance surface, and one of said opposite side surfaces is a light exit surface;

a light source disposed adjacent to said light entrance surface of said light guide plate for emitting light toward said light entrance surface; and

a light deflecting film disposed adjacent and parallel to the light exit surface of said light guide plate, said light deflecting film having a multilayer structure wherein light reflecting layers and light transmitting layers are stacked one by one alternately, said reflecting layers and said transmitting layers being tilted at a predetermined angle relative to said light exit surface.

2. A backlight unit according to claim 1, wherein a stacking direction of said reflecting layers and said transmitting layers in said light deflecting film is coincident with a light traveling direction in which light from said light source is directed to enter said light guide plate through said light entrance surface.

3. A backlight unit according to claim 2, wherein said light reflecting layers and said light transmitting layers extend perpendicular to said light traveling direction and said predetermined angle is less than 90 degrees and faces in said light traveling direction.

4. A backlight unit according to claim 3, wherein said tilt angle is in a range of 60-80 degrees.

5. A backlight unit according to claim 4, wherein said tilt angle is in a range of 65-75 degrees.

6. A backlight unit according to claim 4, wherein an overall size in the stacking direction of said reflecting layer and said transmitting layer that are positioned adjacent each other is less or equal to 0.2 mm, and a size in the stacking direction of said reflecting layer is less or equal to 1 micron.

7. A backlight unit according to claim 6, wherein a size of said light deflecting film in a direction normal to said light exit surface is less or equal to 0.3 mm.