Rearview Mirror Assemblies With Anisotropic Polymer Laminates

• US 20100277786A1
• Filed: 05/05/2010
• Published: 11/04/2010
• Est. Priority Date: 07/10/2008
• Status: Active Grant

• Current Assignee: Gentex Corporation
• Original Assignee: Gentex Corporation
• Inventors: Morgan, Tammy G., Neuman, George A., Tonar, William L., Anderson, John S., Luten, Henry A., Dozeman, Gary J.
• Granted Patent: US 9,254,789 B2
• Time in Patent Office: Days
• US Class Current: 359/247
• CPC Class Codes: B60R 1/088 using a cell of electrically changeable optical characteristic, e.g. liquid-crystal or electrochromic mirrors
• CPC Class Codes: B60R 1/12 Mirror assemblies combined with other articles, e.g. clocks
• CPC Class Codes: G02B 27/28 for polarising used in stereoscopes G02B30/25
• CPC Class Codes: G02B 5/0816 Multilayer mirrors, i.e. having two or more reflecting layers G02B5/0883, G02B5/0891 take precedence
• CPC Class Codes: G02B 5/3058 comprising electrically conductive elements, e.g. wire grids, conductive particles
• CPC Class Codes: G02F 1/0136 for the control of polarisation, e.g. state of polarisation [SOP] control, polarisation scrambling, TE-TM mode conversion or separation G02F1/0353 takes precedence
• CPC Class Codes: G02F 1/1313 specially adapted for a particular application
• CPC Class Codes: G02F 1/133357 Planarisation layers
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/13475 in which at least one liquid crystal cell or layer is doped with a pleochroic dye, e.g. GH-LC cell G02F1/13476 takes precedence
• CPC Class Codes: G02F 1/13725 based on guest-host interaction G02F1/13762, G02F1/13737, take precedence
• CPC Class Codes: G02F 1/1516 comprising organic material
• CPC Class Codes: G02F 1/1523 comprising inorganic material
• CPC Class Codes: G02F 1/157 Structural association of cells with optical devices, e.g. reflectors or illuminating devices
• CPC Class Codes: G02F 1/163 Operation of electrochromic cells, e.g. electrodeposition cells; Circuit arrangements therefor
• CPC Class Codes: G02F 2201/44 Arrangements combining different electro-active layers, e.g. electrochromic, liquid crystal or electroluminescent layers

Abstract

Anisotropic film laminates for use in image-preserving reflectors such as rearview automotive mirror assemblies, and related methods of fabrication. A film may comprise an anisotropic layer such as a light-polarizing layer and other functional layers. The film having controlled water content is heated under omnidirectional pressure and vacuum to a temperature substantially equal to or above a lower limit of a glass-transition temperature range of the film so as to be laminated to a substrate. The laminate is configured as part of a mirror structure so as to increase contrast of light produced by a light source positioned behind the mirror structure and transmitted through the mirror structure towards a viewer. The mirror structure is devoid of any extended distortion and is characterized by SW and LW values less than 3, more preferably less than 2, and most preferably less than 1.

Claims

1. A switchable mirror system (SMS) for use in a vehicular rearview assembly equipped with a light source transmitting light from within the rearview assembly through said SMS to a field-of-view (FOV) outside the assembly, the SMS comprising:

at least two electro-optic (EO) cells defined by at least three sequentially disposed spaced-apart substrates, a first EO-cell corresponding to an outside portion of the rearview assembly and a second EO-cell disposed between the first EO-cell and the light source,

wherein the first EO-cell is adapted to be a switchable linear absorptive polarizer thereby configuring said SMS to have a reflectance value that is gradually variable in response to changes in voltages applied to the first and second EO-cells, as measured in said FOV in ambient light.

2. An SMS according to claim 1, further comprising at least two linear reflective polarizers disposed so as to sandwich an EO-medium of the second EO-cell between said linear reflective polarizers.

3. An SMS according to claim 2, wherein at least one of the first and second EO-cells includes a thin-film alignment layer having an anisotropic surface.

4. An SMS according to claim 2, wherein at least one of said at least two linear reflective polarizers includes multiple layers of plastic film.

5. An SMS according to claim 2, wherein at least one of said two linear reflective polarizers includes a wire-grid polarizer.

6. An SMS according to claim 5, further comprising a thin-film planarization layer overcoating said wire-grid polarizer, the planarization layer having a substantially flat surface.

7. An SMS according to claim 1, wherein a substrate from the at least three substrates is a polymer-based linear reflective polarizer.

8. An SMS according to claim 1, wherein the first and second EO-cells share a common substrate.

9. An SMS according to claim 1, wherein molecules of an EO-medium of the first EO-cell change their spatial orientations in response to a voltage applied to said first EO-cell thereby keeping a transmittance value of the SMS substantially unchanged during the gradual variation of said reflectance value.

10. An SMS according to claim 1, wherein said switchable linear absorptive polarizer includes an electrochromic (EC) element containing orientated EC medium.

11. An SMS according to claim 1, wherein said switchable linear absorptive polarizer includes a guest-host liquid-crystal cell containing a dye, and wherein the second EO-cell includes a twisted nematic liquid-crystal medium.

12. An SMS according to claim 1 configured within said rearview assembly, said rearview assembly further comprising at least one additional device selected from the group consisting of an illumination assembly, a display, a voice activated system, a compass system, a telephone system, a highway toll booth interface, a telemetry system, a headlight controller, a glare sensor, a rain sensor, a tire pressure monitoring system, a navigation system, a lane departure warning system, and an adaptive cruise control system.

13. A switchable mirror system (SMS) for use in a rearview assembly equipped with a light source transmitting light from within the assembly through said SMS to a field-of-view (FOV) outside the assembly, said SMS comprising:

at least two electro-optic (EO) cells defined by at least three sequentially disposed spaced-apart substrates, a first EO-cell corresponding to an outside portion of the rearview assembly and a second EO-cell disposed between the first EO-cell and the light source; and

two linear reflective polarizers disposed on two sequentially disposed substrates from the at least three substrates so as to sandwich an EO-medium of the second EO-cell between said two linear reflective polarizers, wherein a distance between said two linear reflective polarizers does not exceed an aggregate value of thicknesses of said two sequentially disposed substrates and a separation therebetween.

14. An SMS according to claim 13, wherein the first EO-cell is adapted to be a switchable linear absorptive polarizer thereby configuring said SMS to have a reflectance value that is gradually variable as measured in said FOV in ambient light;

15. An SMS according to claim 13, wherein the first and second EO-cells share a common substrate.

16. An SMS according to claim 13, wherein at least one of the two linear reflective polarizer includes multiple layers of plastic film.

17. An SMS according to claim 13, wherein said distance does not exceed an aggregate value of a thickness of one of the two sequentially disposed substrates and said separation therebetween.

18. An SMS according to claim 13, wherein said distance does not exceed the separation between said two sequentially disposed substrates.

19. An SMS according to claim 13, wherein the gradually variable reflectance is measured in D₆₅ standard illuminant light.

20. A method according to claim 13, wherein the switchable absorptive polarizer is a guest-host liquid-crystal device.

21. An SMS according to claim 13, wherein a combination of said two linear reflective polarizers and an EO-medium of the second EO-cell is configured to substantially transmit light having a first polarization and substantially reflect light having a second polarization when no voltage is applied to the second EO-cell, and to substantially reflect light having either the first or the second polarization when a non-zero voltage is applied to the second EO-cell, the first and second polarizations being mutually orthogonal.

22. An SMS according to claim 13 configured within the rearview assembly wherein said light source includes a light emitter and a display, wherein the display is located between the light emitter and said SMS and is illuminated by the light emitter, the rearview assembly further comprising

a third linear reflective polarizer disposed between said SMS and the light emitter so as to increase a level of transmission of polarized light from the display through the SMS to said FOV.

23. An SMS according to claim 22, wherein said level of transmission of polarized light exceeds 70 percent.

24. An SMS according to claim 22, wherein said level of transmission of polarized light exceeds 80 percent.

25. A switchable mirror system (SMS) for use in a vehicular rearview assembly equipped with a light source transmitting light from within the rearview assembly through said SMS to a field-of-view (FOV) outside the assembly, the SMS comprising:

at least two electro-optic (EO) cells defined by at least three sequentially disposed spaced-apart glass substrates, a first EO-cell corresponding to an outside portion of the rearview assembly and a second EO-cell disposed between the first EO-cell and the light source,

wherein the first EO-cell is adapted to be a switchable linear absorptive polarizer thereby configuring said SMS to have a reflectance value that is gradually variable in response to changes in voltages applied to the first and second EO-cells, as measured in said FOV in ambient light, and

wherein thicknesses of said at least three substrates are chosen to provide for a net weight, of said SMS, per unit area of less than 2.0 grams per cm².

26. An SMS according to claim 25, further comprising first and second linear reflective polarizers disposed within the SMS so as to sandwich an EO-medium of the second EO-cell between said first and second linear reflective polarizers.

27. An SMS according to claim 26, wherein at least one of the first and second linear reflective polarizers includes multiple layers of plastic film.

28. An SMS according to claim 26, wherein a combination of said two linear reflective polarizers and an EO-medium of the second EO-cell is configured to substantially transmit light having a first polarization and substantially reflect light having a second polarization when no voltage is applied to the second EO-cell, and to substantially reflect light having either the first or the second polarization when a non-zero voltage is applied to the second EO-cell, the first and second polarizations being mutually orthogonal.

29. An SMS according to claim 26 configured within said rearview assembly, said rearview assembly further comprising at least one additional device selected from the group consisting of an illumination assembly, a display, a voice activated system, a compass system, a telephone system, a highway toll booth interface, a telemetry system, a headlight controller, a glare sensor, a rain sensor, a tire pressure monitoring system, a navigation system, a lane departure warning system, and an adaptive cruise control system.