Color-compensated information displays

• US 6,624,936 B2
• Filed: 05/10/2001
• Issued: 09/23/2003
• Est. Priority Date: 05/11/2000
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Gilligan, Gregory E., Kotchick, Keith M., Ebihara, Ikuko
• Primary Examiner(s): Chang, Audrey
• Assistant Examiner(s): Curtis, Craig
• Application Number:
  US09/853,051
• Publication Number:
  US 20010055153A1
• Time in Patent Office: 866 Days
• Field of Search: 359/490, 359/485, 359/491, 349/119, 349/97, 349/187
• US Class Current: 359/485.03
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133533 Colour selective polarisers G02F1/1347 takes precedence

Abstract

A polarizer has low color shift and is particularly well suited to use in an LCD display. The polarizer has a double pass color shift of |Δx|≦0.005 and |Δy|≦0.005 for illumination by a C-illuminant, and a double pass contrast modulation of at least 90%. The display includes two or more layers stacked together, at least one of the layers being an absorbing polarizer having a double pass color shift of |Δx|≦0.005 and |Δy|≦0.005 for illumination by a C-illuminant. A polarizer with a selected color shift is also used with a rear projection screen having a dispersing layer stacked together with first absorbing polarizer. The polarizer has a single pass color shift with at least one of Δx and Δy being negative under illumination by a C-illuminant, and a polarization co-efficiency greater than 90%.

Claims

1. An optical device, comprising:

an absorbing polarizer having a double pass color shift of |Δ

x|≦

0.005 and |Δ

y|≦

0.005 for illumination by a C-illuminant, and a double pass contrast modulation of at least 90%;

a liquid crystal display (LCD) layer disposed below the absorbing polarizer; and

a reflective layer disposed below the LCD layer to reflect back light through the LCD and the absorbing polarizer to form an image.

2. A device as recited in claim 1, wherein the absorbing polarizer has a double pass color shift of |Δ

x|≦

0.004 and |Δ

y|≦

0.004 for illumination by a C-illuminant.

3. A device as recited in claim 1, wherein the absorbing polarizer has a double pass color shift of |Δ

x|≦

0.002 and |Δ

y ≦

0.003 for illumination by a C-illuminant.

4. A device as recited in claim 1, wherein the absorbing polarizer has a double pass contrast modulation of more than 95%.

5. A device as recited in claim 1, wherein the absorbing polarizer has a double pass contrast modulation of more than 97%.

6. A device as recited in claim 1, wherein the absorbing polarizer has a double pass efficiency of more than 60%.

7. A device as recited in claim 1, wherein the absorbing polarizer has a double pass efficiency of more than 68%.

8. A device as recited in claim 1, wherein the absorbing polarizer includes iodine as a polarization sensitive absorber.

9. A device as recited in claim 1, wherein the absorbing polarizer exhibits a double pass color shift having a negative value for Δ

x when illuminated by an A-illuminant.

10. A device as recited in claim 1, wherein the absorbing polarizer exhibits a double pass color shift having a color shift of Δ

x<

0.005 and Δ

y<

0.002 when illuminated by an A-illuminant.

11. A device as recited in claim 10, wherein the absorbing polarizer exhibits a double pass color shift having a value of Δ

x<

0.003 when illuminated by an A-illuminant.

12. A device as recited in claim 1, wherein light is blue shifted after double passing the absorbing polarizer.

13. An optical device, comprising:

an absorbing polarizer having a double pass color shift of Δ

x≦

0.005 and Δ

y≦

0.002 and a double pass contrast modulation of at least 90% under illumination by an A-illuminant, and a double pass color shift of Δ

x≦

0.005 and Δ

y≦

0.005 under illumination by a C-illuminant;

a liquid crystal display (LCD) layer disposed below the absorbing polarizer; and

a reflective layer disposed below the LCD layer to reflect back light through the LCD and the absorbing polarizer to form an image.

14. A device as recited in claim 13, wherein the double pass color shift Δ

x under illumination by the A-illuminant is negative.

15. A device as recited in claim 13, wherein the absorbing polarizer has a double pass contrast modulation of more than 95% under illumination by the A-illuminant.

16. A device as recited in claim 13, wherein the absorbing polarizer has a double pass contrast modulation of more than 97% under illumination by the A-illuminant.

17. A device as recited in claim 13, wherein the absorbing polarizer has a double pass efficiency of more than 60% under illumination by the A-illuminant.

18. A device as recited in claim 13, wherein the absorbing polarizer has a double pass efficiency of more than 68% under illumination by the A-illuminant.

19. A device as recited in claim 13, wherein light is blue shifted after double passing the absorbing polarizer.

20. A device as recited in claim 13, wherein the absorbing polarizer includes iodine as a polarization sensitive absorber.

21. A device for displaying information, comprising:

two or more layers stacked together, at least one of the layers being an absorbing polarizer having a double pass color shift of |Δ

x|≦

0.005 and |Δ

y|≦

0.005 for illumination by a C-illuminant, and at least one of the layers including a liquid crystal display (LCD) layer disposed below the absorbing polarizer and a reflective layer disposed below the LCD layer to reflect back light through the LCD and the absorbing polarizer to form an image.

22. A device as recited in claim 21, wherein the double pass color shift through the two or more layers stacked together is less than |Δ

x|≦

0.01 and |Δ

y|≦

0.015 for illumination by a C-illuminant.

23. A device as recited in claim 21, wherein the reflective layer is a transflective layer.

24. A device as recited in claim 21, wherein the LCD layer further includes color filters for respective pixels of the LCD layer.

25. A device as recited in claim 21, further comprising a control unit coupled to the LCD layer to control polarization rotation of individual pixels of the LCD layer, so as to present an image on the device to a user.

26. A device as recited in claim 21, wherein one of the two or more layers includes a touch sensitive panel.

27. A device as recited in claim 23, further comprising a backlight disposed below the transflective layer.

28. A device as recited in claim 23, wherein the transflective layer has a single reflection color shift of |Δ

x|≦

0.005 and |Δ

y|≦

0.002 for illumination by a C-illuminant.

29. A device as recited in claim 23, wherein the transflective layer is a reflecting polarizer.

30. A device as recited in claim 29, wherein the reflecting polarizer has a pass polarization direction either substantially perpendicular or substantially parallel to a pass polarization direction of the absorbing polarizer.

31. A device as recited in claim 29, wherein the reflecting polarizer has a pass polarization direction oriented to be neither perpendicular nor parallel to a pass polarization direction of the absorbing polarizer.

32. A device as recited in claim 29, wherein the reflecting polarizer includes one of a multilayer reflecting polarizer, a wire grid polarizer, a cholesteric polarizer, and a dispersed phase polarizer.

33. A device as recited in claim 32, wherein the reflecting polarizer includes a cholesteric polarizer coupled to a retarding layer.