Dual-mode LCD backlight

• US 6,639,349 B1
• Filed: 06/16/2000
• Issued: 10/28/2003
• Est. Priority Date: 06/16/2000
• Status: Expired due to Fees

• Current Assignee: Rockwell Collins, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Rockwell Collins, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Bahadur, Birendra
• Primary Examiner(s): Patel, Vip
• Assistant Examiner(s): QUARTERMAN, KEVIN J
• Application Number:
  US09/595,197
• Time in Patent Office: 1,229 Days
• Field of Search: 313/483, 313/484, 313/485, 313/489, 362/260, 362/227, 362/228, 362/229, 349/68
• US Class Current: 313/483
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: F21Y 2105/00 Planar light sources
• CPC Class Codes: F21Y 2113/20 of different form
• CPC Class Codes: F21Y 2115/15 Organic light-emitting diodes [OLED]
• CPC Class Codes: G02F 1/133626 providing two modes of illumination, e.g. day-night

Abstract

A light system is disclosed that may be used as a dual-mode LCD backlight. The light system includes a fluorescent lamp and a secondary light source that is attached to or formed upon an outer surface of the fluorescent lamp. The fluorescent lamp diffuses the light of the secondary light source.

Claims

1. A light system comprising:

a fluorescent lamp having an outer surface; and

a secondary light source disposed upon the outer surface of the fluorescent lamp, the fluorescent lamp diffusing the light of the secondary light source.

2. The light system of claim 1, wherein the fluorescent lamp has an inner surface that is partially coated with a phosphor substance such that a portion of the inner surface is free of the phosphor substance.

3. The light system of claim 2, wherein the secondary light source is attached to the outer surface of the fluorescent lamp proximal the portion of the inner surface that is free of the phosphor substance.

4. The light system of claim 1, wherein the secondary light source includes an electro luminescent element.

5. The light system of claim 4, wherein the electroluminescent element includes a layer of electroluminescent material disposed between first and second conductive layers, and wherein the first conductive layer is formed upon the outer surface of the fluorescent lamp.

6. The light system of claim 5, wherein the first conductive layer is substantially transparent.

7. The light system of claim 4, wherein the secondary light source is an organic light-emitting diode.

8. The light system of claim 1, wherein the secondary light source is a light-emitting diode.

9. The light system of claim 1, wherein the secondary light source includes an optical filter that is positioned to selectively filter light produced by the secondary light source.

10. A dual-mode LCD backlight, comprising:

a fluorescent lamp that provides a first luminance level when activated;

a secondary light source, disposed upon the fluorescent lamp, that provides a second luminance level when activated;

wherein the second luminance level is smaller than the first luminance level.

11. The LCD backlight of claim 10, wherein the secondary light source is attached to the fluorescent lamp.

12. The LCD backlight of claim 10, wherein the secondary light source includes an electro luminescent element.

13. The LCD backlight of claim 12, wherein the electro luminescent element includes a layer of electro luminescent material disposed between first and second conductive layers, and wherein the first conductive layer is substantially transparent and is formed upon an outer surface of the fluorescent lamp.

14. The LCD backlight of claim 10, wherein the secondary light source includes an optical filter that is positioned to selectively filter light produced by the secondary light source.

15. The LCD backlight of claim 10, wherein the light emitted by the secondary light source includes ultraviolet light.

16. The LCD backlight of claim 10, further including a substantially planar waveguide having a planar surface and an edge surface disposed at an angle with respect to the planar surface, wherein the fluorescent lamp is situated adjacent the edge surface, and further wherein light exits the waveguide through the planar surface.