Displays With Reflective Polarizers

• US 20150009451A1
• Filed: 07/03/2013
• Published: 01/08/2015
• Est. Priority Date: 09/14/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Zhu, Xinyu, Qi, Jun, Jiao, Meizi, Roland, Nicholas G., Yin, Victor H., Chen, Wei
• Granted Patent: US 9,239,490 B2
• Time in Patent Office: Days
• US Class Current: 349/64
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 2413/12 Biaxial compensators

Abstract

An electronic device may be provided with a display mounted in a housing. The display may include a liquid crystal display module and a reflective polarizer having an in-plane optical axis. The display may also include a backlight unit that includes a light source, a light guide element, and a reflector film coupled to a backside of the light guide element. The display may also include a light retardation layer such as a quarter wave film. The quarter wave film may be arranged between the reflective polarizer and the reflector film of the backlight unit. During operation of the display, partially polarized light that is output from a front side of the light guide element may have a first component parallel to the in-plane optical axis and a second component perpendicular to the in-plane optical axis of the reflective polarizer. The second component may be reflected from the reflective polarizer.

Claims

1. A display, comprising:

a liquid crystal display module;

a backlight unit having a reflector;

optical films that include a diffuser film and a prism film having prism elements that face the backlight unit; and

a reflective polarizer interposed between the reflector and the liquid crystal display module.

2. The display defined in claim 1, further comprising:

a quarter wave film.

3. The display defined in claim 2 wherein the quarter wave film is interposed between the diffuser film and the reflective polarizer.

4. The display defined in claim 2 wherein the quarter wave film is interposed between the diffuser film and the prism film.

5. The display defined in claim 2 wherein the backlight unit further comprises a light guide layer and wherein the quarter wave film is interposed between the prism film and the light guide layer.

6. The display defined in claim 2 wherein the backlight unit further comprises a light guide layer and wherein the quarter wave film is interposed between the light guide layer and the reflector.

7. A display, comprising:

a liquid crystal display module;

a backlight unit having a reflector;

optical films that include top and bottom diffuser films arranged on opposing sides of first and second prism films having crossed prism elements that face the liquid crystal display module; and

a reflective polarizer interposed between the reflector and the liquid crystal display module.

8. The display defined in claim 7, further comprising:

a quarter wave film.

9. The display defined in claim 8 quarter wave film is interposed between the top diffuser film and the reflective polarizer.

10. The display defined in claim 8 wherein the quarter wave film is interposed between the top diffuser film and the first prism film.

11. The display defined in claim 8 wherein the quarter wave film is interposed between the bottom diffuser film and the second prism film.

12. The display defined in claim 8 wherein the quarter wave film is interposed between the bottom diffuser layer and the backlight unit.

13. The display defined in claim 8 wherein the backlight unit further comprises a light guide layer and wherein the quarter wave film is interposed between the light guide layer and the reflector.

14. A display, comprising:

a liquid crystal display module;

a backlight unit having a reflector;

a diffuser film; and

a reflective polarizer interposed between the reflector and the liquid crystal display module.

15. The display defined in claim 14, further comprising:

a quarter wave film.

16. The display defined in claim 15 wherein the quarter wave film is interposed between the diffuser film and the reflective polarizer.

17. The display defined in claim 15 wherein the quarter wave film is interposed between the diffuser film and the backlight unit.

18. The display defined in claim 15 wherein the backlight unit further comprises a light guide layer and wherein the quarter wave film is interposed between the light guide layer and the reflector.

19. A display, comprising:

a liquid crystal display module having upper and lower polarizer layers;

a backlight unit having a reflector; and

a reflective polarizer interposed between the reflector and the liquid crystal display module.

20. The display defined in claim 19, further comprising a light retardation film between the reflective polarizer and the reflector.

21. The display defined in claim 20 wherein the light retardation film comprises a quarter wave film.

22. The display defined in claim 21 wherein the quarter wave film comprises a uniaxial quarter wave film.

23. The display defined in claim 22, further comprising:

a uniaxial c-film adjacent to the uniaxial quarter wave film, wherein the uniaxial quarter wave film is interposed between the uniaxial c-film and the reflective polarizer.

24. The display defined in claim 23, further comprising:

an additional uniaxial c-film interposed between the reflective polarizer and the uniaxial quarter wave film.

25. The display defined in claim 22, further comprising:

a uniaxial c-film interposed between the reflective polarizer and the uniaxial quarter wave film.

26. The display defined in claim 21 wherein the quarter wave film comprises a biaxial quarter wave film.