Non-inverting transflective assembly

• US 6,985,291 B2
• Filed: 10/01/2001
• Issued: 01/10/2006
• Est. Priority Date: 10/01/2001
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Kotchick, Keith M., Allen, Richard C., Watson, Philip E.
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): Stevenson, Andre' C.
• Application Number:
  US09/968,817
• Publication Number:
  US 20030063236A1
• Time in Patent Office: 1,562 Days
• Field of Search: 359/490, 353/31, 349/61
• US Class Current: 359/487.02
• CPC Class Codes: G02B 27/286 for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34
• CPC Class Codes: G02B 5/3016 involving passive liquid crystal elements optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 2203/09 transflective

Abstract

A film that includes a first reflective polarizer substantially reflecting light having a first polarization state and substantially transmitting light having a second polarization state, a polarization rotating layer or depolarizing layer (or both) positioned to receive light passing through the first reflective polarizer, and a second reflective polarizer positioned to receive light passing through the polarization rotating layer or depolarizing layer, the second reflective polarizer substantially reflecting light having a third polarization state back through the polarization rotating layer or depolarizing and substantially transmitting light having a fourth polarization state. Articles containing the film can be formed.

Claims

1. An assembly, comprising:

a first reflective polarizer substantially reflecting light having a first polarization state and substantially transmitting light having a second polarization state;

a polarization rotating layer positioned to receive light passing through the first reflective polarizer; and

a second reflective polarizer positioned to receive light passing through the polarization rotating layer, the second reflective polarizer substantially reflecting light having a third polarization state back through the polarization rotating layer and substantially transmitting light having a fourth polarization state.

2. The assembly of claim 1, wherein the polarization rotating layer is positioned to rotate light reflected by the second reflective polarizer.

3. The assembly of claim 1, further comprising a depolarizing layer disposed between the first and second reflective polarizers, the depolarizing layer converting a portion of incident light into an orthogonal polarization state, wherein the second reflective polarizer is positioned to receive light passing through the polarization rotating layer and the depolarizing layer.

4. The assembly of claim 1, further comprising a backlight system positioned to receive light from the second reflective polarizer, the backlight system comprising a reflector.

5. The assembly of claim 1, further comprising an absorbing polarizer positioned to receive light from an external light source, the absorbing polarizer substantially absorbing light having a fifth polarization state and substantially transmitting light having a sixth polarization state.

6. The assembly of claim 1, wherein the transmission axis of the first reflective polarizer is substantially aligned with a transmission axis of the second reflective polarizer.

7. The assembly of claim 5, wherein the transmission axis of the absorbing polarizer is substantially aligned with a transmission axis of the first reflective polarizer.

8. The assembly of claim 7, wherein the transmission axis of the first reflective polarizer is substantially aligned with a transmission axis of the second reflective polarizer.

9. The assembly of claim 5, wherein the transmission axis of the first reflective polarizer is not substantially aligned with a transmission axis of the absorbing polarizer, the assembly further comprising a second polarization rotator disposed between the first reflective polarizer and the absorbing polarizer.

10. The assembly of claim 1, wherein the first reflective polarizer is coupled to the polarization rotating layer.

11. The assembly of claim 9, wherein the polarization rotating layer is coupled to the second reflective polarizer.

12. The assembly of claim 1, wherein the polarization rotating layer is a liquid crystal polymer polarization rotator.

13. The assembly of claim 1, wherein the polarization rotating layer is a half-wave plate.

25. The assembly of claim 1, wherein the polarization rotating layer is configured and arranged to rotate polarization of light by a fixed angle.

26. The assembly of claim 25, wherein the polarization rotating layer comprises a liquid crystal polymer material crosslinked to retain alignment of the liquid crystal polymer material.

27. The assembly of claim 25, wherein the polarization rotating layer comprises a liquid crystal polymer material vitrified to retain alignment of the liquid crystal polymer material.

14. An assembly, comprising:

a first reflective polarizer substantially reflecting light having a first polarization state and substantially transmitting light having a second polarization state;

a depolarizing layer positioned to receive light passing through the first reflective polarizer, the depolarizing layer converting a portion of incident light into an orthogonal polarization state; and

a second reflective polarizer positioned to receive light passing through the depolarizing layer, the second reflective polarizer substantially reflecting light having a third polarization state back through the depolarizing layer and substantially transmitting light having a fourth polarization state.

15. The assembly of claim 14, further comprising a backlight system positioned to receive light from the second reflective polarizer, the backlight system comprising a reflector.

16. The assembly of claim 14, further comprising an absorbing polarizer positioned to receive light from an external light source, the absorbing polarizer absorbing light having a fifth polarization state and transmitting light having a sixth polarization state.

17. The assembly of claim 14, wherein the transmission axis of the first reflective polarizer is substantially aligned with a transmission axis of the second reflective polarizer.

18. The assembly of claim 16, wherein the transmission axis of the absorbing polarizer is substantially aligned with a transmission axis of the first reflective polarizer.

19. The assembly of claim 18, wherein the transmission axis of the first reflective polarizer is substantially aligned with a transmission axis of the second reflective polarizer.

20. The assembly of claim 15, wherein the transmission axis of the first reflective polarizer is not substantially aligned with a transmission axis of the absorbing polarizer, the assembly further comprising a polarization rotator disposed between the first reflective polarizer and the absorbing polarizer.

21. The assembly of claim 14, wherein the first reflective polarizer is coupled to the depolarizing layer.

22. The assembly of claim 21, wherein the depolarizing layer is coupled to the second reflective polarizer.

23. The assembly of claim 14, wherein the depolarizing layer is a diffuse adhesive layer.

24. The assembly of claim 14, wherein a surface of the depolarizing layer is roughened.