Electrochromic mirror having a self-cleaning hydrophilic coating

• US 6,816,297 B1
• Filed: 06/23/2000
• Issued: 11/09/2004
• Est. Priority Date: 06/25/1999
• Status: Expired due to Fees

• Current Assignee: Gentex Corporation
• Original Assignee: Gentex Corporation
• Inventors: Cammenga, David J., Tonar, William L., Anderson, John S.
• Primary Examiner(s): Shafer, Ricky D.
• Application Number:
  US09/602,919
• Time in Patent Office: 1,600 Days
• Field of Search: 359/265, 359/267, 359/269, 359/272, 359/273, 359/274, 359/275, 359/507, 359/512
• US Class Current: 359/265
• CPC Class Codes: B60R 1/0602 comprising means for cleaning or deicing
• CPC Class Codes: B60R 1/088 using a cell of electrically changeable optical characteristic, e.g. liquid-crystal or electrochromic mirrors
• CPC Class Codes: G02B 1/105 Protective coatings
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• CPC Class Codes: G02B 27/0006 with means to keep optical surfaces clean, e.g. by preventing or removing dirt, stains, contamination, condensation G02B1/18 takes precedence; cleaning in general B08B
• CPC Class Codes: G02F 1/157 Structural association of cells with optical devices, e.g. reflectors or illuminating devices

Abstract

An electro-optic device is disclosed having a self-cleaning, hydrophilic optical coating. The electro-optic device preferably forms an external rearview mirror for a vehicle. The optical coating preferably includes photocatalytic layer(s), a hydrophilic layer, and a color suppression coating. The electro-optic device is preferably an electrochromic mirror. The disclosed optical coating exhibits a reflectance at the front surface of the reflective element that is less than about 20 percent, and has sufficient hydrophilic properties such that water droplets on a front surface of the optical coating exhibit a contact angle of less than about 20°. The mirror exhibits a C* value of less than 25.

Claims

1. An electrochromic mirror, comprising:

first and second substrates each having front and rear surfaces spaced apart and sealed to provide a chamber therebetween, the front surface of said first substrate having a self-cleaning hydrophilic coating associated therewith;

a first electrode disposed on the rear surface of said first substrate;

a color suppressing layer disposed on a surface of said first substrate, said color suppressing layer having a refractive index intermediate one of said first electrode or said self-cleaning hydrophilic coating and said first substrate, wherein said color suppressing layer reduces the color of the electrochromic mirror in an activated state;

a reflector disposed on one of said front or rear surfaces of said second substrate such that when said reflector is on said rear surface of said second substrate, then said front surface of said rear substrate contains a layer of a transparent conductive material; and

an electrochromic medium disposed in the chamber.

2. The electrochromic medium as defined in claim 1, wherein said first electrode is made of indium tin oxide.

3. The electrochromic medium as defined in claim 1, wherein said first electrode has a half wave optical thickness.

4. The electrochromic medium as defined in claim 1, wherein said first electrode has a full wave optical thickness.

5. The electrochromic medium as defined in claim 1, wherein said color suppressing layer has a quarter wave optical thickness.

6. The electrochromic medium as defined in claim 1, wherein said color suppressing layer comprises Al₂O₃.

7. The electrochromic medium as defined in claim 1, wherein said electrochromic medium comprises a color such that, when combined with said first substrate, said self-cleaning hydrophilic coating, and said color suppressing layer, the C* value of said electrochromic mirror in an activated state decreases relative to the same without said color-suppressing layer.