System for collimating backlight

• US 7,573,642 B2
• Filed: 02/26/2008
• Issued: 08/11/2009
• Est. Priority Date: 03/26/2002
• Status: Active Grant

• Current Assignee: Rambus Delaware LLC (Rambus Inc.)
• Original Assignee: Brilliant Film, LLC
• Inventors: Wojciechowski, Timothy J., Lubart, Neil D., Lash, Thomas E.
• Primary Examiner(s): Harrington; Alicia M
• Application Number:
  US12/037,262
• Publication Number:
  US 20080144182A1
• Time in Patent Office: 532 Days
• Field of Search: 359/641, 359/619, 359/622, 359/708, 359/712, 359/718, 362/551, 362/559, 362/268, 349/114
• US Class Current: 359/641
• CPC Class Codes: G02B 17/002 Arrays of reflective systems
• CPC Class Codes: G02B 27/0972 Prisms prisms per se G02B5/04
• CPC Class Codes: G02B 27/0983 being curved
• CPC Class Codes: G02B 27/30 Collimators
• CPC Class Codes: G02F 1/133524 Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses

Abstract

A collimating device and a transflector for use in a system having a backlight is disclosed herein. In one embodiment of the application, the collimating device and the transflector each include an immersing layer, a reflecting layer, and an optical element layer formed from a plurality of three-dimensional, optical elements. Each optical element is tapered such that a small area end has a horizontal plane cross-sectional area that is less than that of a wide area end. The optical elements of the collimating device are tapered towards the backlight and the optical elements of the transflector are tapered away from the backlight. The reflecting layer has apertures which correspond to the position and shape of the light input ends of the optical elements.

Claims

1. A collimating device for use in a system having a backlight, the collimating device comprising:

an immersing layer;

a reflecting layer; and

an optical element layer formed from a plurality of three-dimensional, optical elements,

each optical element having a light input end and a light output end, each optical element being tapered towards the backlight such that the light input end has a horizontal plane cross-sectional area that is less than that of the light output end,

wherein each optical element has a vertical plane cross-section that includes at least one curved section that is an approximation of a compound parabolic concentrator and includes at least one linear section, such that uncollimated light entering the light input end of the optical element from multiple angles emerges from the light output end of the optical end as a substantially uniform sheet, and wherein the curved section is defined by an arc of a circle, and a slope of the curved section matches a slope of the at least one linear section at the intersection point of the curved section and the at least one linear section, and

wherein the reflecting layer has apertures therein which correspond to the position and shape of the light input ends of the optical elements.

2. The collimating device of claim 1, wherein the optical elements are surrounded by air.

3. The collimating device of claim 1, wherein the optical element layer is formed from a polymer having a first index of refraction and the optical elements are surrounded by a second polymer having a second index of refraction, the first index of refraction being higher than the second index of refraction.

4. The collimating device of claim 1, wherein the light output end of each optical element abuts the light output end of at least one other optical element of the optical element layer.

5. The collimating device of claim 1, wherein the immersing layer has a first and second side and the reflecting layer has a first and second side, and wherein the first side of the immersing layer is in contact with the second side of the reflecting layer.

6. The collimating device of claim 5, wherein the light input ends of the optical elements extend such that the light input ends contact the second side of the reflecting layer.

7. The collimating device of claim 5, wherein the light input ends of the optical elements extend through the apertures of the reflecting layer and contact the second side of the immersing layer.

8. The collimating device of claim 1, wherein the immersing layer has a first and second side and the reflecting layer has a first and second side, and wherein the first side of the reflecting layer is in contact with the second side of the immersing layer and the light input ends of the optical elements are in contact with the first side of the immersing layer.

9. The collimating device of claim 1, wherein the reflecting layer is a metal layer.

10. The collimating device of claim 1, wherein the immersing layer is an immersing polymer layer.

11. The collimating device of claim 1, wherein each optical element has a polygonal horizontal plane cross-section.

12. The collimating device of claim 1, wherein each optical element is lenticular shaped and has a horizontal plane cross-section that is rectangular with length equal to that of the lenticular channel.

13. The collimating device of claim 1, wherein the reflecting layer comprises a material having a reflectivity of 80% or greater.

14. A transflector configured to reflect light arriving from a first direction and to transmit light arriving from a second direction opposite the first direction, the transflector comprising:

at least one immersing layer, including a first immersing layer having a first and second side, wherein the first side faces a backlight that projects light in the first direction and the second side faces light arriving from the second direction;

at least one reflective layer, including a first reflective layer having a first and second side, wherein the first side faces the backlight and the second side faces light arriving from the second direction;

at least one optical element layer, including a first optical element layer having a first set of optical elements, wherein each of the first set of optical elements are tapered towards the light arriving from the second direction, such that each optical element has a small area end and a large area end, wherein the large area end of each of the first set of optical elements contacts the large area end of another of the first set of optical elements, and

wherein the first reflective layer has apertures therein which correspond to the positioning and shape of the small area ends of each of the first set of optical elements.

15. The transflector of claim 14, wherein the first side of the first reflective layer is in contact with the second side of the first immersing layer, and the small area ends of the first set of optical elements are in contact with the second side of the first reflective layer.

16. The transflector of claim 14, wherein the first side of the first immersing layer is in contact with the second side of the first reflective layer, and the small area ends of the first set of optical elements are in contact with the second side of the first immersing layer.

17. The transflector of claim 14, wherein the first side of the first reflective layer is in contact with the second side of the first immersing layer, and the small area ends of the first set of optical elements extend through the apertures of the first reflective layer and contact the second side of the first immersing layer.

18. The transflector of claim 14, wherein the at least one optical element layer includes a second optical element layer having a second set of optical elements, each of the second set of optical elements being tapered towards the backlight, such that each optical element has a small area end and a large area end and the large area ends of the second set of optical elements are adjacent to the large area ends of the first set of optical elements;

wherein the at least one reflective layer includes a second reflective layer having a first side and a second side, such that the first side faces the backlight and the second side faces light arriving from the second direction, the second reflective layer further having apertures therein which correspond to the positioning and shape of the small area ends of each of the second set of optical elements;

wherein the at least one immersing layer includes a second immersing layer having a first side and a second side, such that the first side faces the backlight and the second side faces light arriving from the second direction.

19. The transflector of claim 18, wherein the first side of the second immersing layer is in contact with the second side of the second reflective layer, and the small area ends of the second set of optical elements are in contact with the first side of the second reflective layer.

20. The transflector of claim 14, wherein the first reflective layer comprises a material having a reflectivity of 80% or greater.

21. A collimating device for use in a system having a backlight, the collimating device comprising:

a reflecting layer; and

an optical element layer formed from a plurality of three-dimensional, optical elements,

each optical element having a light input end and a light output end, each optical element being tapered towards the backlight such that the light input end has a horizontal plane cross-sectional area that is less than that of the light output end,

wherein each optical element has a vertical plane cross-section that includes at least one curved section that is an approximation of a compound parabolic concentrator and includes at least one linear section, such that uncollimated light entering the light input end of the optical element from multiple angles emerges from the light output end of the optical end as a substantially uniform sheet, and wherein the curved section is defined by an arc of a circle, and a slope of the curved section matches a slope of the at least one linear section at the intersection point of the curved section and the at least one linear section, and

wherein the reflecting layer has apertures therein which correspond to the position and shape of the light input ends of the optical elements.

22. The collimating device of claim 21, wherein each optical element has a polygonal horizontal plane cross-section.

23. The collimating device of claim 21, wherein each optical element is lenticular shaped and has a horizontal plane cross-section that is rectangular with length equal to that of the lenticular channel.

24. The collimating device of claim 21, wherein the reflecting layer comprises a material having a reflectivity of 80% or greater.

25. A device comprising:

transflective pixels having a reflective surface; and

an optical element layer having a plurality of light containing regions,

wherein each light containing region is tapered along a curved path towards the transflective pixels, such that each light containing region has a small area end and a wide area end,

wherein the small area ends are aligned with the transflective pixels.

26. The device of claim 25, further comprising:

a plurality of color filters aligned with the transflective pixels.

27. The device of claim 25, further comprising:

a backlight;

a front polarizer;

a rear polarizer; and

at least one glass layer.

28. The device of claim 27, wherein the at least one glass layer includes a front glass layer.

29. The device of claim 27, wherein the at least one glass layer includes a front glass layer and a rear glass layer.

30. The device of claim 25, wherein the device includes a collimating layer having a plurality of light containing regions and a reflective layer.

31. The device of claim 25, wherein the reflective surface comprises a material having a reflectivity of 80% or greater.