Semiconductor light source configured as a light tube

• US 7,549,782 B2
• Filed: 05/11/2006
• Issued: 06/23/2009
• Est. Priority Date: 05/11/2006
• Status: Expired due to Fees

• Current Assignee: Document Security Systems, Inc.
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Lee, Sian Tatt, Ng, Kee Yean
• Primary Examiner(s): O'Shea, Sandra L
• Assistant Examiner(s): APENTENG, JESSICA MCMILLAN
• Application Number:
  US11/432,833
• Publication Number:
  US 20070263405A1
• Time in Patent Office: 1,139 Days
• Field of Search: 362/555, 362/551, 362/800, 362/26, 362/27, 362/84, 362/231, 362/293, 362/552, 362/553, 362/558, 362/582, 362/583
• US Class Current: 362/555
• CPC Class Codes: F21K 9/27 Retrofit light sources for lighting devices with two fittings for each light source, e.g. for substitution of fluorescent tubes
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: F21K 9/69 Details of refractors forming part of the light source
• CPC Class Codes: F21Y 2113/13 comprising an assembly of point-like light sources
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 6/0003 the light guides being doped with fluorescent agents
• CPC Class Codes: G02B 6/001 the light being emitted along at least a portion of the lateral surface of the fibre

Abstract

A tubular light source having a semiconductor light source and a tube is disclosed. The tube includes a transparent medium, the tube having a side tube surface, a center curve, one end surface, a length, and a maximum cross-sectional dimension. The tube includes scattering centers that cause light traveling in the tube to be reflected at angles such that the reflected light leaves the tube through the side tube surface. The semiconductor light source is positioned to emit light into the tube within a cone of angles such that the light will not leave the side tube surface in the absence of the scattering centers. The scattering centers can be dispersed in the transparent medium or located on the side tube surface. The transparent medium can be rigid or flexible.

Claims

1. A light source comprising:

a semiconductor light source;

a tube comprising a transparent medium, said tube having a side tube surface, a center curve, one end surface, a length, and a maximum cross-sectional dimension, said tube having scattering centers that cause light traveling in said tube to be reflected at angles such that said reflected light leaves said tube through said side tube surface;

said semiconductor light source being positioned to emit light into said tube within a cone of angles such that said light will not leave said side tube surface in the absence of said scattering centers, wherein said length is greater than 10 times said maximum cross-sectional dimension;

wherein said scattering centers are dispersed throughout said transparent medium; and

phosphorescent material located at each of said scattering centers.

2. The light source of claim 1 wherein said end surface comprises a reflective material for reflecting light striking said end surface back into said tube.

3. The light source of claim 1 wherein said center curve comprises a portion of a circle.

4. The light source of claim 1 wherein said center curve comprises a straight line.

5. The light source of claim 1 wherein said transparent medium comprises an elastomeric material.

6. The light source of claim 1 wherein said semiconductor light source comprises an LED.

7. The light source of claim 1 wherein said semiconductor light source comprises a laser.

8. The light source of claim 1 wherein said scattering centers are dispersed such that said light leaving said side tube surface has a substantially uniform intensity as a function of position along said center curve.

9. The light source of claim 1 wherein said tube comprises first and second ends and wherein said semiconductor light source comprises a first light emitter that injects light into said first end and a second light emitter that injects light into said second end.

10. The light source of claim 1 further comprising a controller that sets an intensity of light emitted by said semiconductor light source in response to an externally generated intensity control signal.

11. The light source of claim 10 wherein said controller controls the spectrum of light emitted from said semiconductor light source in response to an externally generated color control signal.

12. The light source of claim 1 wherein said scattering centers are distributed uniformly throughout said transparent medium.

13. The light source of claim 1 and further wherein:

said phosphorescent material converts light from said semiconductor light source to light having a different spectrum from that emitted by said semiconductor light source.

14. The light source of claim 1 and further wherein:

said scattering centers comprise at least a first plurality of scattering centers and a second plurality of scattering centers;

said phosphorescent material comprises a first type of phosphor and a second type of phosphor;

said first type of phosphor is located at each of said first plurality of scattering centers; and

said second type of phosphor is located at each of said second plurality of scattering centers.

15. The light source of claim 14 and further wherein:

said first type of phosphor converts light from said semiconductor light source to light having a first spectrum which is different from the spectrum of light emitted by said semiconductor light source; and

said second type of phosphor converts light from said semiconductor light source to light having a second spectrum which is different from said first spectrum and which is different from said spectrum of light emitted by said semiconductor light source.