Displays with reflective polarizers

• US 9,239,490 B2
• Filed: 07/03/2013
• Issued: 01/19/2016
• 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
• Primary Examiner(s): Nguyen, Sang V
• Application Number:
  US13/935,110
• Publication Number:
  US 20150009451A1
• Time in Patent Office: 930 Days
• Field of Search: 349/64, 349/96, 349/87, 362/623, 362/362, 359/487, 359/494
• US Class Current: 1/1
• 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 having upper and lower polarizer layers;

a backlight unit having a reflector;

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

a uniaxial quarter wave film between the reflective polarizer and the reflector;

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; and

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

2. The display defined in claim 1 further comprising a diffuser film and a prism film, wherein the diffuser film is interposed between the prism film and the uniaxial quarter wave film.

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

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

5. The display defined in claim 4 wherein the prism film comprises prism elements that face the backlight unit.

6. The display defined in claim 1 further comprising 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.

7. The display defined in claim 6 wherein the uniaxial quarter wave film is interposed between the top diffuser film and the first prism film.

8. The display defined in claim 6 wherein the uniaxial quarter wave film is interposed between the bottom diffuser film and the second prism film.

9. The display defined in claim 6 wherein the uniaxial quarter wave film is interposed between the bottom diffuser layer and the backlight unit.

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

11. The display defined in claim 1 further comprising a diffuser.

12. The display defined in claim 11 wherein the reflective polarizer separates the diffuser from the lower polarizer.