Color sequential illumination system

• US 5,260,625 A
• Filed: 10/10/1991
• Issued: 11/09/1993
• Est. Priority Date: 10/15/1990
• Status: Expired due to Fees

• Current Assignee: Central Research Fund Limited
• Original Assignee: Thorn EMI Plc (Universal Music Group NV)
• Inventors: Shanks, Ian A., Carrington, Andrew N., Holden, John G.
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): PATEL, NIMESHKUMAR D
• Application Number:
  US07/774,315
• Time in Patent Office: 761 Days
• Field of Search: 313/486, 313/487, 313/504, 313/493, 313/497, 313/635, 313/501, 359/48, 359/50, 362/260
• US Class Current: 313/486
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: C09K 11/08 containing inorganic luminescent materials
• CPC Class Codes: F21K 2/00 Non-electric light sources using luminescence using excitation by radioactivity G21H3/02, H01J65/06, H01J65/08; using excitation by an external electromagnetic field or by external corpuscular radiation H01J65/04; Light sources using electrochemiluminescence
• CPC Class Codes: G02B 6/0003 the light guides being doped with fluorescent agents
• CPC Class Codes: G02F 1/133622 Colour sequential illumination
• CPC Class Codes: H01J 61/42 by transforming the wavelength of the light by luminescence

Abstract

A color sequential illumination system, such as, for example, a backlighting system for a liquid crystal display (LCD), comprises lamps for emitting blue, red and green light. The red and green light is provided by lamps including fluorescent dyes having optical decay times similar to a phosphor material used to provide the blue light. In this manner, the blue, red and green emissions can be fully synchronized with electrical signals used to energise the lamps, enhancing color range and color quality. Furthermore, if the fluorescent dyes are carried in plastics materials, then trapping and concentration of the light generated may also be achieved, providing enhanced brightness for the LCD for a given power input.

Claims

1. A colour sequential illumination system comprising:

a plurality of illumination means for generating light of respective colour characteristics;

each illumination means including a phosphor for producing light by excitation thereof;

at least one illumination means further including organic fluorescent material for receiving light emitted by the phosphor and emitting in response light having a respective colour characteristic, the or each organic fluorescent material having an optical decay time which is of substantially less duration than the optical decay time of a phosphor material possessing a corresponding colour characteristic, whereby all illumination means of the plurality have substantially equal optical decay times.

2. A system according to claim 1 wherein the organic fluorescent material comprises a dye.

3. A system according to claim 1 wherein the organic fluorescent material comprises a plastics material.

4. A system according to claim 1 wherein the illumination means includes a gas discharge tube.

5. A system according to claim 1 wherein the illumination means includes an arc lamp.

6. A system according to claim 1 wherein the colour characteristic is red.

7. A system according to claim 1 wherein the colour characteristic is green.

8. A system according to claim 1 wherein the optical decay time is less than 0.1 milliseconds.