ELECTRONIC DEVICE AND LC SHUTTER FOR POLARIZATION-SENSITIVE SWITCHING BETWEEN TRANSPARENT AND DIFFUSIVE STATES

• US 20090201446A1
• Filed: 02/08/2008
• Published: 08/13/2009
• Est. Priority Date: 02/08/2008
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Polak, Robert, Ishikawa, Tomohiro, Zhuang, Jim
• Granted Patent: US 8,059,232 B2
• Time in Patent Office: Days
• US Class Current: 349/97
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/1336 Illuminating devices
• CPC Class Codes: G02F 1/133626 providing two modes of illumination, e.g. day-night

Abstract

An electronic device (200) includes a display (202) and an LC shutter (204), at least a portion of which is operatively positioned over the display (202). The LC shutter (204) provides switching between a transparent state and a diffusive state with high image integrity, and high transmission in the transparent state. In one embodiment, the electronic device (200) further includes control logic (206) operatively coupled to the LC shutter (204) to provide control signals (212) to the LC shutter (204) to effect the transparent state. The LC shutter (204) includes a first dichroic polarizer (300), such as a broadband dichroic polarizer, a specular reflective polarizer (302), such as a broadband reflective polarizer, an LC cell (304), and a diffusive reflective polarizer (306). The LC cell (304) is interposed between the first dichroic polarizer (300) and the specular reflective polarizer (302). The diffusive reflective polarizer (306) is interposed between the LC cell (304) and the specular reflective polarizer (302). Related methods are also set forth.

Claims

1. An LC shutter comprising:

a first dichroic polarizer;

a specular reflective polarizer;

an LC cell interposed between the first dichroic polarizer and the specular reflective polarizer; and

an in-plane anisotropic diffuser interposed between the LC cell and the specular reflective polarizer.

2. The LC shutter of claim 1, further comprising a second dichroic polarizer that is a narrowband dichroic polarizer interposed between the in-plane anisotropic diffuser and the specular reflective polarizer, and wherein the first dichroic polarizer is a broadband dichroic polarizer and the specular reflective polarizer is a broadband specular reflective polarizer.

3. The LC shutter of claim 1, further comprising a second dichroic polarizer that is a narrowband dichroic polarizer interposed between the LC cell and the in-plane anisotropic diffuser, and wherein the first dichroic polarizer is a broadband dichroic polarizer and the specular reflective polarizer is a broadband specular reflective polarizer.

4. The LC shutter of claim 1, wherein the first dichroic polarizer is a broadband dichroic polarizer and the specular reflective polarizer is a broadband specular reflective polarizer.

5. The LC shutter of claim 4, further comprising a second dichroic polarizer that is a broadband dichroic polarizer, and wherein the LC cell, the in-plane anisotropic diffuser, and the specular reflective polarizer are interposed between the first dichroic polarizer and the second dichroic polarizer.

6. The LC shutter of claim 2, further comprising a third dichroic polarizer that is a broadband dichroic polarizer, and wherein the LC cell, the in-plane anisotropic diffuser, the second dichroic polarizer, and the specular reflective polarizer are interposed between the first dichroic polarizer and the third dichroic polarizer.

7. The LC shutter of claim 3, further comprising a third dichroic polarizer that is a broadband dichroic polarizer, and wherein the LC cell, the second dichroic polarizer, the in-plane anisotropic diffuser, and the specular reflective polarizer are interposed between the first dichroic polarizer and the third dichroic polarizer.

8. The LC shutter of claim 1, wherein the first dichroic polarizer is a broadband dichroic polarizer and the specular reflective polarizer is a narrowband specular reflective polarizer.

9. The LC shutter of claim 8, further comprising a second dichroic polarizer that is a broadband dichroic polarizer, and wherein the LC cell, the in-plane anisotropic diffuser, and the specular reflective polarizer are interposed between the first dichroic polarizer and the second dichroic polarizer.

10. The LC shutter of claim 1, wherein the in-plane anisotropic diffuser comprises:

a matrix; and

at least one domain dispersed within the matrix;

wherein the in-plane anisotropic diffuser is such that there is a refractive index match between the matrix and the at least one domain along a first axis of the in-plane anisotropic diffuser, and a refractive index mismatch between the matrix and the at least one domain along a second axis of the in-plane anisotropic diffuser, and wherein the first axis and the second axis are substantially in a plane of the in-plane anisotropic diffuser.

11. An electronic device comprising:

a display operative to emit light; and

at least a portion of an LC shutter operatively positioned over the display, and wherein the LC shutter further comprises;

a first dichroic polarizer;

a specular reflective polarizer;

an LC cell interposed between the first dichroic polarizer and the specular reflective polarizer; and

an in-plane anisotropic diffuser interposed between the LC cell and the specular reflective polarizer.

12. The electronic device of claim 11, wherein at least a portion of the LC shutter is further operatively positioned over a keypad operative to emit light.

13. The electronic device of claim 11, further comprising a radio-telephone subsystem operatively coupled to the display.

14. The electronic device of claim 11, further comprising a second dichroic polarizer that is a narrowband dichroic polarizer interposed between the in-plane anisotropic diffuser and the specular reflective polarizer, and wherein the first dichroic polarizer is a broadband dichroic polarizer and the specular reflective polarizer is a broadband specular reflective polarizer.

15. The electronic device of claim 11, further comprising a second dichroic polarizer that is a narrowband dichroic polarizer interposed between the LC cell and the in-plane anisotropic diffuser, and wherein the first dichroic polarizer is a broadband dichroic polarizer and the specular reflective polarizer is a broadband specular reflective polarizer.

16. The electronic device of claim 11, wherein:

the first dichroic polarizer is a broadband dichroic polarizer and the specular reflective polarizer is a broadband specular reflective polarizer,

the LC shutter further comprises a second dichroic polarizer that is a broadband dichroic polarizer, and

the LC cell, the in-plane anisotropic diffuser, and the specular reflective polarizer are interposed between the first dichroic polarizer and the second dichroic polarizer.

17. The electronic device of claim 14, wherein the LC shutter further comprises a third dichroic polarizer that is a broadband dichroic polarizer, and wherein the LC cell, the in-plane anisotropic diffuser, the second dichroic polarizer, and the specular reflective polarizer are interposed between the first dichroic polarizer and the third dichroic polarizer.

18. The electronic device of claim 15, wherein the LC shutter further comprises a third dichroic polarizer that is a broadband dichroic polarizer, and wherein the LC cell, the second dichroic polarizer, the in-plane anisotropic diffuser, and the specular reflective polarizer are interposed between the first dichroic polarizer and the third dichroic polarizer.

19. The electronic device of claim 11, wherein the first dichroic polarizer is a broadband dichroic polarizer and the specular reflective polarizer is a narrowband specular reflective polarizer.

20. The electronic device of claim 19, wherein the LC shutter further comprises a second dichroic polarizer that is a broadband dichroic polarizer, and wherein the LC cell, the in-plane anisotropic diffuser, and the specular reflective polarizer are interposed between the first dichroic polarizer and the second dichroic polarizer.