Variable reflectance mirrors and windows

• US 7,502,156 B2
• Filed: 07/12/2005
• Issued: 03/10/2009
• Est. Priority Date: 07/12/2004
• Status: Active Grant

• Current Assignee: Gentex Corporation
• Original Assignee: Gentex Corporation
• Inventors: Tonar, William L., Bauer, Frederick T., Watson, Alan R.
• Primary Examiner(s): PRITCHETT, JOSHUA L
• Application Number:
  US11/179,793
• Publication Number:
  US 20060007550A1
• Time in Patent Office: 1,337 Days
• Field of Search: 359/604, 359/265, 359/267
• US Class Current: 359/267
• CPC Class Codes: B60R 1/088 using a cell of electrically changeable optical characteristic, e.g. liquid-crystal or electrochromic mirrors

Abstract

Various structures for variable reflectance rearview mirrors and variable transmittance windows are disclosed. One embodiment pertains to the provision of a polarized reflector in a rearview mirror. Another embodiment pertains to the provision of a switchable cholesteric liquid crystal element in a window. Yet another embodiment pertains to the provision of a plurality of apertures in a reflector layer of a rearview mirror where the apertures are sized and positioned in alignment with light emitting areas of a display positioned behind the reflector layer. In another embodiment, a moveable display or mirror element is attached to a rearview mirror housing.

Claims

1. A variable reflectance mirror element for use in a rearview mirror assembly having an electronic device positioned behind the mirror element for transmitting/receiving light of a first polarization, said mirror element comprising:

a first substrate;

a second substrate;

a first electrode provided on a surface of said first substrate;

a second electrode provided on a surface of said second substrate;

an electro-optic medium provided between said first and second substrates that changes transmittance of the mirror element in response to a voltage applied across said first and second electrodes; and

a polarized reflector provided on or near a surface of said second substrate for transmitting light of the first polarization and reflecting light of a second polarization opposite the first polarization, wherein said polarized reflector is positioned in front of the electronic device such that the electronic device transmits/receives light of the first polarization through said polarized reflector.

2. The mirror element of claim 1, wherein said polarized reflector is electrically conductive and functions as said second electrode.

3. The mirror element of claim 1, wherein said polarized reflector is a wire grid polarizer.

4. The mirror element of claim 1, wherein said electro-optic medium comprises an electrochromic medium.

5. The mirror element of claim 4, wherein said polarized reflector comprises a cholesteric liquid crystal element, which also functions as said polarized reflector.

6. The mirror element of claim 5, wherein said cholesteric liquid crystal element is switchable.

7. The mirror element of claim 1, wherein said mirror element is a switchable cholesteric liquid crystal element.

8. The mirror element of claim 1, wherein said mirror element further comprises a first switchable cholesteric liquid crystal element, which also functions as said polarized reflector, and a second switchable cholesteric liquid crystal element.

9. A rearview mirror assembly for a vehicle comprising:

an electro-optic element comprising first and second electrodes, said electro-optic element changes reflectance in response to a voltage applied across said first and second electrodes, wherein said second electrode comprises a polarized reflector for transmitting light of a first polarization and reflecting light of a second polarization opposite the first polarization; and

an electronic device positioned behind said polarized reflector for transmitting/receiving light of the first polarization through said polarized reflector.

10. The rearview mirror assembly of claim 9, wherein said electronic device is a light sensor.

11. The rearview mirror assembly of claim 10, wherein said light sensor is positioned to sense glare light levels from the rear of the vehicle.

12. The rearview mirror assembly of claim 9, wherein said electronic device is a display.

13. The rearview mirror assembly of claim 12, wherein said display is a compass display.

14. The rearview mirror assembly of claim 12, wherein said display is a video display.

15. The rearview mirror assembly of claim 12, wherein said display is a rear vision display.

16. The rearview mirror assembly of claim 12, wherein said display is a liquid crystal display.

17. The rearview mirror assembly of claim 9, wherein said electronic device is a light source.

18. The rearview mirror assembly of claim 17, wherein said light source is a turn signal.

19. The rearview mirror assembly of claim 9, wherein said electro-optic element comprises an electrochromic element.

20. The rearview mirror assembly of claim 9, wherein said polarized reflector is a wire grid polarizer.

21. The rearview mirror assembly of claim 9, wherein said electro-optic element comprises a switchable cholesteric liquid crystal element, which also serves as said polarized reflector.

22. The rearview mirror assembly of claim 9, wherein said electro-optic element comprises a first switchable cholesteric liquid crystal element, which also functions as said polarized reflector, and a second switchable cholesteric liquid crystal element.

23. An electrochromic element comprising:

a first substrate;

a second substrate spaced apart from said first substrate;

a first electrode provided on a surface of said first substrate;

a second electrode provided on a surface of said second substrate;

an electrochromic medium provided between said first and second substrates; and

a polarized reflector provided on a surface of one of said first and second substrates, said polarized reflector transmits light of a first polarization and reflects light of a second polarization opposite the first polarization;

wherein said second electrode includes a second layer of conductive material, and wherein said polarized reflector is disposed between said second substrate and said second layer of conductive material.

24. An electrochromic element comprising:

a first substrate;

a second substrate spaced apart from said first substrate;

a first electrode provided on a surface of said first substrate;

a second electrode provided on a surface of said second substrate;

an electrochromic medium provided between said first and second substrates; and

a polarized reflector provided on a surface of one of said first and second substrates, said polarized reflector transmits light of a first polarization and reflects light of a second polarization opposite the first polarization;

wherein said polarized reflector is provided on the same surface of said second substrate as said second electrode.

25. An electrochromic element comprising:

a first substrate;

a second substrate spaced apart from said first substrate;

a first electrode provided on a surface of said first substrate;

a second electrode provided on a surface of said second substrate;

an electrochromic medium provided between said first and second substrates; and

a polarized reflector provided on a surface of one of said first and second substrates, said polarized reflector transmits light of a first polarization and reflects light of a second polarization opposite the first polarization;

wherein said second electrode is provided on a first surface of said second substrate, and said polarized reflector is provided on a second surface of said second substrate that is opposite said first surface.

26. The electrochromic element 25, wherein said first electrode includes a first layer of conductive material provided over substantially the entire surface of said first substrate and said second electrode includes a second layer of conductive material provided over substantially the entire surface of said second substrate.

27. The electrochromic element 26, wherein said polarized reflector is disposed between said second substrate and said second layer of conductive material.