Liquid crystal mirror adapted to filter light in the mesopic wavelength region

• US 8,736,805 B2
• Filed: 06/20/2006
• Issued: 05/27/2014
• Est. Priority Date: 09/21/2005
• Status: Active Grant

• Current Assignee: Alphamicron Incorporated
• Original Assignee: Alphamirror, Inc.
• Inventors: Borenstein, Yehuda, Taheri, Bahman
• Primary Examiner(s): NGUYEN, DUNG T
• Application Number:
  US11/922,932
• Publication Number:
  US 20090109393A1
• Time in Patent Office: 2,898 Days
• Field of Search: 349/1, 349/113, 349/95, 349193-195, 359265-275
• US Class Current: 349/195
• CPC Class Codes: B60R 1/088 using a cell of electrically changeable optical characteristic, e.g. liquid-crystal or electrochromic mirrors
• CPC Class Codes: G02F 1/13 based on liquid crystals, e.g. single liquid crystal display cells
• CPC Class Codes: G02F 1/13318 Circuits comprising a photodetector

Abstract

A mirror system, comprising a spectrally selective liquid crystal reflective assembly, designed and constructed to substantially absorb or transmit light at wavelengths corresponding to mesopic conditions, while reflecting light at other wavelengths. In one embodiment, the reflectance level of the mirror system is altered in response to a voltage applied across the selective liquid crystal reflective assembly.

Claims

1. A mirror system, comprising a spectrally selective liquid crystal reflective assembly having a transmissive liquid crystal medium that when activated, substantially partially absorbs light at wavelengths from about 490 nanometers to about 550 nanometers, while transmitting light at other wavelengths, resulting in the mirror system reflecting light at the other wavelengths,

wherein said liquid crystal reflective assembly is responsive to a voltage such that when said voltage is applied across said liquid crystal reflective assembly, a reflectance level of said liquid crystal reflective assembly is altered,

wherein said liquid crystal reflective assembly further comprises an electronic circuitry for varying a level of said voltage at a predetermined rate thereby altering a reflectance level of said liquid crystal reflective assembly at said predetermined rate,

wherein said electronic circuitry is designed and configured to receive ambient light information and rear light information, and to select said level of said voltage and said predetermined rate based on said ambient light information, said rear light information or a combination thereof.

2. The system of claim 1, further comprising an ambient light sensor for collecting and transmitting said ambient light information to said electronic circuitry, and a rear light sensor for collecting and transmitting said rear light information to said electronic circuitry.

3. The system of claim 1, wherein said ambient light information and said rear light information each independently comprises light illuminance information.

4. The system of claim 1, wherein said ambient light information and said rear light information each independently comprises light brightness information.

5. The system of claim 1, wherein said ambient light information and said rear light information each independently comprises light spectral information.

6. The system of claim 1, further comprising a user interface communicating with said electronic circuitry.

7. The system of claim 6, wherein said electronic circuitry receives from said user interface a characteristic response information of a user to light and uses said characteristic response information to select or adjust a threshold value and corresponding reflectance level of said mirror system.

8. The system of claim 6, wherein said electronic circuitry is designed and configured to receive from said user interface a characteristic response information of a user to light and to select or adjust said predetermined rate based on said characteristic response information.

9. The system of claim 1, wherein said predetermined rate is selected from a set of discrete rates, each rate of said set of discrete rates corresponding to a different ambient light condition.

10. The system of claim 9, wherein each rate of said set of discrete rates corresponds to a different illuminance range, a different brightness range, or a different predominant wavelength range of said ambient light or said rear light, or both.

11. The system of claim 1, wherein said predetermined rate is a monotonic decreasing function of an illuminance of said ambient light or said rear light, or both.

12. The system of claim 1, wherein said predetermined rate is a monotonic decreasing function of a brightness of said ambient light or said rear light, or both.

13. The system of claim 1, wherein said predetermined rate is a non-monotonic function of a predominant wavelength of said ambient light or said rear light, or both.

14. The system of claim 1, wherein said electronic circuitry is designed and configured to vary said level of said voltage at a continuous or step-wise varying rate.

15. The system of claim 1, serving as a rearview mirror of a vehicle.

16. A mirror system, comprising a spectrally selective liquid crystal reflective assembly comprising a transmissive liquid crystal medium that preferentially absorbs light corresponding to mesopic conditions and reflects light at the non-absorbed wavelengths,

wherein said liquid crystal reflective assembly is responsive to a voltage such that when said voltage is applied across said liquid crystal reflective assembly, a reflectance level of said liquid crystal reflective assembly is altered,

wherein said liquid crystal reflective assembly further comprises an electronic circuitry for varying a level of said voltage at a predetermined rate thereby altering a reflectance level of said liquid crystal reflective assembly at said predetermined rate,

wherein said electronic circuitry is designed and configured to receive ambient light information and rear light information, and to select said level of said voltage and said predetermined rate based on said ambient light information, said rear light information or a combination thereof.

17. The system of claim 16, wherein the liquid crystal medium is characterized by an absorption curve having a peak at a wavelength of 510-530 nanometers.

18. The system of claim 16, wherein the liquid crystal medium is characterized by an absorption curve having a peak at a wavelength of 510-530 nanometers and a half width at half max of about 50 nanometers.

19. The system of claim 16, wherein the liquid crystal medium is characterized by an absorption curve wherein light having a wavelength of about 490 to about 550 nm is preferentially absorbed more than light having a wavelength above 550 or below 490 nm.

20. The system of claim 16, further comprising an ambient light sensor for collecting and transmitting said ambient light information to said electronic circuitry, and a rear light sensor for collecting and transmitting said rear light information to said electronic circuitry.

21. The system of claim 20, further comprising a user interface communicating with said electronic circuitry.

22. The system of claim 21, wherein said electronic circuitry receives from said user interface a characteristic response information of a user to light and selects or adjusts said predetermined rate based on said characteristic response information.

23. The system of claim 22, wherein said predetermined rate is selected from a set of discrete rates, each rate of said set of discrete rates corresponding to a different ambient light condition.

24. The system of claim 23, wherein each rate of said set of discrete rates corresponds to a different illuminance range or brightness range of said ambient light or said rear light, or both.

25. The system of claim 23, wherein each rate of said set of discrete rates corresponds to a different predominant wavelength range of said ambient light or said rear light, or both.

26. The system of claim 20, wherein said electronic circuitry receives from said user interface a characteristic response information of a user to light and uses said characteristic response information to select or adjust a threshold value and corresponding reflectance level of said mirror system.

27. The system of claim 16, wherein said electronic circuitry varies said level of said voltage at a continuous or step-wise varying rate.

28. The system of claim 16, serving as a rearview mirror of a vehicle.