Total internal reflection fresnel lens and optical system using the same

• US 20060050241A1
• Filed: 09/07/2004
• Published: 03/09/2006
• Est. Priority Date: 09/07/2004
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Engstrom, Frederic R.
• Granted Patent: US 7,350,925 B2
• Time in Patent Office: Days
• US Class Current: 353/46
• CPC Class Codes: G03B 21/10 Projectors with built-in or built-on screen
• CPC Class Codes: G03B 21/625 Lenticular translucent screens

Abstract

Described is an optical lens having a light-receiving surface facing a light source and a first structured surface opposite a first portion of the light-receiving surface. The first structured surface includes a plurality of first reflecting surfaces and first refractive surfaces. Each of the first refractive surfaces receives light from a corresponding first reflective surface for refractive transmission therethrough. The optical system may further include a second structured surface opposite a second portion of the light-receiving surface. The second structured surface includes a plurality of second refractive surfaces. Each of the second refractive surfaces receives light directly from the light-receiving surface. Where the first and second structured surfaces are included, the first and second portions of the light-receiving surface can be positioned so that light projected from the light source at an angle above a threshold angle falls on the first portion and light at an angle below the threshold angle falls on the second portion.

Claims

1. An optical system comprising:

a light source;

a light-receiving surface facing the light source to receive light therefrom; and

a first structured surface opposite a first portion of the light-receiving surface, the first structured surface including a plurality of first reflecting surfaces projecting at a plurality of first angles relative to the light-receiving surface and a plurality of first refractive surfaces projecting at a plurality of second angles relative to the light-receiving surface, each of the first refractive surfaces receiving light from a corresponding one of the first reflective surfaces for refractive transmission therethrough.

2. The optical system according to claim 1, wherein a first one of the first angles is different than a second one of the first angles, and a first one of the second angles is different than a second one of the second angles.

3. The optical system according to claim 1, wherein at least one of the first angles is greater than ninety degrees.

4. The optical system according to claim 1, wherein at least one of the first angles is approximately one hundred degrees.

5. The optical system according to claim 1, wherein the first structured surface is a total internal reflection Fresnel lens.

6. The optical system according to claim 1, further comprising a second structured surface opposite a second portion of the light-receiving surface, the second structured surface including a plurality of second refractive surfaces projecting at a plurality of third angles relative to the light-receiving surface, each of the second refractive surfaces receiving light directly from the light-receiving surface for refractive transmission therethrough, wherein the first and second portions of the light-receiving surface are positioned so that light from the light source incident on the light-receiving surface at an angle above a threshold angle falls on the first portion and light incident on the light-receiving surface at an angle below the threshold angle falls on the second portion.

7. The optical system according to claim 6, wherein a first one of the third angles is different than a second one of the third angles.

8. The optical system according to claim 6, wherein the first structured surface is a total internal reflection Fresnel lens and the second structured surface is a refractive Fresnel lens.

9. The optical system according to claim 6, wherein the first structured surface and the second structured surface have a substantially semicircular outer shape.

10. The optical system according to claim 6, wherein the first structured surface and the second structured surface have a substantially rectangular outer shape.

11. The optical system according to claim 6, wherein the threshold angle is selected so that a portion of light transmitted through the first structured surface is substantially equal to a portion of light transmitted through the second structured surface.

12. The optical system according to claim 6, wherein the threshold angle is from about forty-two to about forty-three degrees.

13. The optical system according to claim 6, wherein the light-receiving surface, the first structured surface and the second structured surface are comprised substantially of acrylic.

14. The optical system according to claim 1, wherein the light-receiving surface is substantially planar.

15. A rear projection display system, comprising:

a light source;

an optical lens, wherein the optical lens includes a light-receiving surface facing the light source to receive light therefrom, and a first structured surface opposite a first portion of the light-receiving surface, the first structured surface including a plurality of first reflecting surfaces projecting at a plurality of first angles relative to the light-receiving surface and a plurality of first refractive surfaces projecting at a plurality of second angles relative to the light-receiving surface, each of the first refractive surfaces receiving light from a corresponding one of the first reflective surfaces for refractive transmission therethrough;

an enclosure situating the light source and optical lens; and

a projection screen disposed to receive light from the optical lens and transmitting light received from the optical lens in a viewing direction.

16. The rear projection display system according to claim 15, wherein the light source is situated at a light source angle greater than forty-two degrees.

17. The rear projection display system according to claim 15, further comprising:

an aspheric mirror receiving light from the light source; and

a back mirror receiving light from the aspheric mirror and reflecting a substantial portion of the light in a direction towards the light-receiving surface.

18. The rear projection display system according to claim 17, wherein the enclosure has a depth of less than twenty percent of a diagonal of the projection screen.

19. The rear projection display system according to claim 15, wherein a first one of the first angles is different than a second one of the first angles, and a first one of the second angles is different than a second one of the second angles.

20. The rear projection display system according to claim 15, wherein at least one of the first angles is greater than ninety degrees.

21. The rear projection display system according to claim 15, wherein at least one of the first angles is approximately one hundred degrees.

22. The rear projection display system according to claim 15, wherein the first structured surface is a total internal reflection Fresnel lens.

23. The rear projection display system according to claim 15, further comprising a second structured surface opposite a second portion of the light-receiving surface, the second structured surface including a plurality of second refractive surfaces projecting at a plurality of third angles relative to the light-receiving surface, each of the second refractive surfaces receiving light directly from the light-receiving surface for refractive transmission therethrough, wherein the first and second portions of the light-receiving surface are positioned so that light from the light source incident on the light-receiving surface at an angle above a threshold angle falls on the first portion and light incident on the light-receiving surface at an angle below the threshold angle falls on the second portion.

24. The rear projection display system according to claim 23, wherein a first one of the third angles is different than a second one or the third angles.

25. The rear projection display system according to claim 23, wherein the first structured surface is a total internal reflection Fresnel lens and the second structured surface is a refractive Fresnel lens.

26. The rear projection display system according to claim 23, wherein the first structured surface and the second structured surface have a substantially semicircular outer shape.

27. The rear projection display system according to claim 23, wherein the first structured surface and the second structured surface have a substantially rectangular outer shape.

28. The rear projection display system according to claim 23, wherein the threshold angle is from about forty-two to about forty-three degrees.

29. The rear projection display system according to claim 23, wherein the light-receiving surface, the first structured surface and the second structured surface are comprised substantially of acrylic.

30. The rear projection display system according to claim 15, wherein the light-receiving surface is substantially planar.

31. The rear projection display system according to claim 15, wherein the light source comprises a projection lens.

32. An optical lens comprising:

a light-receiving surface for receiving light; and

a first structured surface opposite a first portion of the light-receiving surface, the first structured surface including a plurality of first reflecting surfaces projecting at a plurality of first angles relative to the light-receiving surface and a plurality of first refractive surfaces projecting at a plurality of second angles relative to the light-receiving surface, each of the first refractive surfaces configured to receive light from a corresponding one of the first reflective surfaces for refractive transmission therethrough.

33. The optical system according to claim 32, wherein a first one of the first angles is different than a second one of the first angles, and a first one of the second angles is different than a second one of the second angles.

34. The optical system according to claim 32, wherein the first structured surface is a total internal reflection Fresnel lens.

35. The optical system according to claim 32, further comprising a second structured surface opposite a second portion of the light-receiving surface, the second structured surface including a plurality of second refractive surfaces projecting at a plurality of third angles relative to the light-receiving surface, each of the second refractive surfaces configured to receive light directly from the light-receiving surface for refractive transmission therethrough;

wherein the first and second portions of the light-receiving surface are configured so that light incident on the light-receiving surface at an angle above a threshold angle falls on the first portion and light incident on the light-receiving surface at an angle below the threshold angle falls on the second portion.

36. The optical system according to claim 35, wherein a first one of the third angles is different than a second one of the third angles.

37. The optical system according to claim 35, wherein the first structured surface is a total internal reflection Fresnel lens and the second structured surface is a refractive Fresnel lens.