Illumination systems with sloped transmission spectrum front reflector

• US 10,162,218 B2
• Filed: 08/29/2016
• Issued: 12/25/2018
• Est. Priority Date: 10/20/2011
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Nevitt, Timothy J., Weber, Michael F., Wheatley, John A., Sousa, Matthew E., Liu, Tao
• Primary Examiner(s): Tso, Laura
• Application Number:
  US15/250,712
• Publication Number:
  US 20160370653A1
• Time in Patent Office: 848 Days
• Field of Search: 362 972
• CPC Class Codes: F21V 13/08 the elements being filters or photoluminescent elements and reflectors
• CPC Class Codes: F21V 7/04 Optical design
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0063 for extracting light out both the major surfaces of the light guide
• CPC Class Codes: G02B 6/0096 the lights guides being of the hollow type
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133605 including specially adapted reflectors
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

A backlight includes a front and back reflector forming a light recycling cavity and one or more light source members disposed to emit light into the light recycling cavity. The front reflector being partially reflective to provide an output illumination area. The front reflector has a blue sloped transmission spectra, at normal incidence with a range among bin values from 15% to 100%.

Claims

1. A backlight comprising:

a front and back reflector forming a light recycling cavity, the front reflector being partially reflective to provide an output illumination area;

one or more light sources disposed to emit light into the light recycling cavity;

wherein the front reflector has a blue sloped transmission spectrum, at normal incidence, with a range among bin values from 15% to 100%.

2. A backlight according to claim 1, wherein the front reflector has a blue-sloped transmission spectrum, at normal incidence, with a range among bin values from 15% to 50%.

3. A backlight according to claim 1, wherein the front reflector comprises a polarizer.

4. A backlight according to claim 1, wherein the front reflector comprises a reflective polarizer.

5. A backlight according to claim 1, wherein the backlight illuminates a liquid crystal display panel.

6. A backlight according to claim 4, wherein the front reflector comprises an absorbing polarizer.