Direct-lit backlight having light recycling cavity with concave transflector

• US 7,815,355 B2
• Filed: 08/27/2005
• Issued: 10/19/2010
• Est. Priority Date: 08/27/2005
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Thompson, David Scott, Kienitz, Scott J., Wheatley, John A., Ostlie, Brian W., Schardt, Craig R.
• Primary Examiner(s): Payne; Sharon E
• Application Number:
  US11/212,166
• Publication Number:
  US 20070047261A1
• Time in Patent Office: 1,879 Days
• Field of Search: 362/560, 362/561, 362/555, 362/624, 362/627, 362/511, 362/330, 313/512
• US Class Current: 362/560
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/133613 characterized by the sequence of light sources

Abstract

Direct-lit backlights and associated methods and components are disclosed in which a transflector that partially transmits and partially reflects incident light is shaped to form at least one concave structure facing a back reflector of the backlight. This provides at least one recycling cavity therebetween, the at least one recycling cavity substantially filling the output area of the backlight. At least one light source is disposed behind the output area to inject light into each cavity, and can be positioned in the recycling cavity or behind an aperture in the back reflector. The cavities are preferably shallow and wide, having a width-to-depth ratio of at least 5 or 10, and can provide uniform brightness and color at the output area with sparsely distributed light sources and in a thin profile backlight.

Claims

1. A direct-lit backlight having an output area, comprising:

a back reflector;

a transflector that partially transmits and partially reflects incident light, the transflector being shaped to form at least one concave structure facing the back reflector to provide one or more recycling cavities therebetween, the one or more recycling cavities substantially filling the output area of the backlight, wherein each recycling cavity has a depth d and a width W, and further wherein W is at least 5 times d; and

at least one light source disposed behind the output area to inject light into the one or more recycling cavities.

2. The backlight of claim 1, wherein each recycling cavity has a depth d and a width W, and W is at least 10 times d.