Light emitting diode (LED) device and method of making same

• US 7,405,857 B2
• Filed: 09/02/2005
• Issued: 07/29/2008
• Est. Priority Date: 01/17/2001
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Everaerts, Albert I., Ma, Jiaying, Zhou, Zhiming, Moshrefzadeh, Robert S.
• Primary Examiner(s): Lee; Diane I.
• Assistant Examiner(s): Cruz; Magda
• Application Number:
  US11/219,231
• Publication Number:
  US 20050286124A1
• Time in Patent Office: 1,061 Days
• Field of Search: 359/222, 359/261, 359/263, 359/317, 359/318, 362/612, 362/555
• US Class Current: 359/261
• CPC Class Codes: G03B 21/60 characterised by the nature of the surface
• CPC Class Codes: G03B 21/602 Lenticular screens G03B21/625 takes precedence
• CPC Class Codes: G03B 21/62 Translucent screens
• CPC Class Codes: G03B 21/625 Lenticular translucent screens

Abstract

A light managing screen may provide a rear projection screen, front projection screen or component thereof. The screen may comprise a polymeric composition including a first polymeric material, and a second polymeric material disposed as a plurality of elongated structures within the first polymeric material. Each elongated structure has a major axis and the major axes are substantially aligned. The first polymeric material has an index of refraction that differs by at least 0.01 from an index of refraction of the second polymeric material. In some instances, a pressure sensitive adhesive material is selected as the first polymeric material. The orientation of the elongated structures and the difference in indices of refraction results in the polymeric composition scattering light asymmetrically.

Claims

1. An optical device, comprising:

a light emitting diode (LED) in which light can be trapped by total internal reflection; and

an adhesive tape positioned on a portion of the LED to extract light therefrom, the tape including an adhesive layer applied to a tape backing;

wherein the adhesive layer includes a first polymeric material dispersed as multiple elongated structures within a second polymeric material.

2. The device of claim 1, wherein the adhesive layer includes a pressure sensitive adhesive.

3. The device of claim 1, wherein the second polymeric material is a pressure sensitive adhesive.

4. The device of claim 1, wherein light that enters the adhesive layer from the LED interacts with the dispersed elongated structures so that the light is scattered.

5. The device of claim 4, wherein at least a portion of the scattered light is scattered out of the tape.

6. The device of claim 1, wherein the adhesive tape extracts light anisotropically from the LED in preferred directions.

7. The device of claim 1, wherein the adhesive tape is disposed over only a restricted portion of a surface of the LED.

8. A method of making a light emitting diode (LED) device, comprising:

providing an LED in which light can be trapped by total internal reflection;

forming an adhesive tape by coating an adhesive composition onto a tape backing; and

positioning the tape on a portion of the LED to extract light therefrom;

wherein the adhesive composition includes a first polymeric material dispersed as multiple elongated structures within a second polymeric material.

9. The method of claim 8, wherein the adhesive composition includes a pressure sensitive adhesive.

10. The method of claim 8, wherein the second polymeric material is a pressure sensitive adhesive.

11. The method of claim 8, wherein light that enters the adhesive composition from the LED interacts with the dispersed elongated structures so that the light is scattered.

12. The method of claim 11, wherein at least a portion of the scattered light is scattered out of the tape.

13. The method of claim 8, wherein the adhesive tape extracts light anisotropically from the LED in preferred directions.

14. The method of claim 8, wherein the positioning step is performed so that the adhesive tape is disposed over only a restricted portion of a surface of the LED.