Optical: systems and elements – Optical modulator – Light wave temporal modulation
Reexamination Certificate
2002-04-03
2004-03-02
Mack, Ricky (Department: 2873)
Optical: systems and elements
Optical modulator
Light wave temporal modulation
C250S21400C, C340S468000
Reexamination Certificate
active
06700692
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to electrochromic devices and rearview mirror assemblies for motor vehicles and, more particularly, to improved electrochromic rearview mirror assemblies.
Heretofore, various rearview mirrors for motor vehicles have been proposed which change from the full reflectance mode (day) to the partial reflectance mode(s) (night) for glare-protection purposes from light emanating from the headlights of vehicles approaching from the rear. Among such devices are those wherein the transmittance is varied by thermochromic, photochromic, or electro-optic means (e.g., liquid crystal, dipolar suspension, electrophoretic, electrochromic, etc.) and where the variable transmittance characteristic affects electromagnetic radiation that is at least partly in the visible spectrum (wavelengths from about 3800 Å to about 7800 Å). Devices of reversibly variable transmittance to electromagnetic radiation have been proposed as the variable transmittance element in variable transmittance light-filters, variable reflectance mirrors, and display devices, which employ such light-filters or mirrors in conveying information. These variable transmittance light filters have included windows.
Devices of reversibly variable transmittance to electromagnetic radiation, wherein the transmittance is altered by electrochromic means, are described, for example, by Chang, “Electrochromic and Electrochemichromic Materials and Phenomena,” in
Non
-
emissive Electrooptic Displays,
A. Kmetz and K. von Willisen, eds. Plenum Press, New York, N.Y. 1976, pp. 155-196 (1976) and in various parts of
Electrochromism,
P. M. S. Monk, R. J. Mortimer, D. R. Rosseinsky, VCH Publishers, Inc., New York, N.Y. (1995). Numerous electrochromic devices are known in the art. See, e.g., Manos, U.S. Pat. No. 3,451,741; Bredfeldt et al., U.S. Pat. No. 4,090,358; Clecak et al., U.S. Pat. No. 4,139,276; Kissa et al., U.S. Pat. No. 3,453,038; Rogers, U.S. Pat. Nos. 3,652,149, 3,774,988 and 3,873,185; and Jones et al., U.S. Pat. Nos. 3,282,157, 3,282,158, 3,282,160 and 3,283,656.
In addition to these devices, there are commercially available electrochromic devices and associated circuitry, such as those disclosed in U.S. Pat. No. 4,902,108, entitled “SINGLE-COMPARTMENT, SELF-ERASING, SOLUTION-PHASE ELECTROCHROMIC DEVICES SOLUTIONS FOR USE THEREIN, AND USES THEREOF,” issued Feb. 20, 1990, to H. J. Byker; Canadian Patent No. 1,300,945, entitled “AUTOMATIC REARVIEW MIRROR SYSTEM FOR AUTOMOTIVE VEHICLES,” issued May 19, 1992, to J. H. Bechtel et al.; U.S. Pat. No. 5,128,799, entitled “VARIABLE REFLECTANCE MOTOR VEHICLE MIRROR,” issued Jul. 7, 1992, to H. J. Byker; U.S. Pat. No. 5,202,787, entitled “ELECTRO-OPTIC DEVICE,” issued Apr. 13, 1993, to H. J. Byker et al.; U.S. Pat. No. 5,204,778, entitled “CONTROL SYSTEM FOR AUTOMATIC REARVIEW MIRRORS,” issued Apr. 20, 1993, to J. H. Bechtel; U.S. Pat. No. 5,278,693, entitled “TINTED SOLUTION-PHASE ELECTROCHROMIC MIRRORS,” issued Jan. 11, 1994, to D. A. Theiste et al.; U.S. Pat. No. 5,280,380, entitled “UV-STABILIZED COMPOSITIONS AND METHODS,” issued Jan. 18, 1994, to H. J. Byker; U.S. Pat. No. 5,282,077, entitled “VARIABLE REFLECTANCE MIRROR,” issued Jan. 25, 1994, to H. J. Byker; U.S. Pat. No. 5,294,376, entitled “BIPYRIDINIUM SALT SOLUTIONS,” issued Mar. 15, 1994, to H. J. Byker; U.S. Pat. No. 5,336,448, entitled “ELECTROCHROMIC DEVICES WITH BIPYRIDINIUM SALT SOLUTIONS,” issued Aug. 9, 1994, to H. J. Byker; U.S. Pat. No. 5,434,407, entitled “AUTOMATIC REARVIEW MIRROR INCORPORATING LIGHT PIPE,” issued Jan. 18, 1995, to F. T. Bauer et al.; U.S. Pat. No. 5,448,397, entitled “OUTSIDE AUTOMATIC REARVIEW MIRROR FOR AUTOMOTIVE VEHICLES,” issued Sep. 5, 1995, to W. L. Tonar; and U.S. Pat. No. 5,451,822, entitled “ELECTRONIC CONTROL SYSTEM,” issued Sep. 19, 1995, to J. H. Bechtel et al. Each of these patents is commonly assigned with the present invention and the disclosures of each, including the references contained therein, are hereby incorporated herein in their entirety by reference. Such electrochromic devices may be utilized in a fully integrated inside/outside rearview mirror system or as separate inside or outside rearview mirror systems.
FIG. 1
shows a typical electrochromic mirror device
10
, having front and rear planar elements
12
and
16
, respectively. A transparent conductive coating
14
is placed on the rear face of the front element
12
, and another transparent conductive coating
18
is placed on the front face of rear element
16
. A reflector (
20
a
,
20
b
and
20
c
), typically comprising a silver metal layer
20
a
covered by a protective copper metal layer
20
b
, and one or more layers of protective paint
20
c
, is disposed on the rear face of the rear element
16
. For clarity of description of such a structure, the front surface of the front glass element is sometimes referred to as the first surface, and the inside surface of the front glass element is sometimes referred to as the second surface. The inside surface of the rear glass element is sometimes referred to as the third surface, and the back surface of the rear glass element is sometimes referred to as the fourth surface. The front and rear elements are held in a parallel and spaced-apart relationship by seal
22
, thereby creating a chamber
26
. The electrochromic medium
24
is contained in space
26
. The electrochromic medium
24
is in direct contact with transparent electrode layers
14
and
18
, through which passes electromagnetic radiation whose intensity is reversibly modulated in the device by a variable voltage or potential applied to electrode layers
14
and
18
through clip contacts and an electronic circuit (not shown).
The electrochromic medium
24
placed in space
26
may include surface-confined, electrode position-type or solution-phase-type electrochromic materials and combinations thereof. In an all solution-phase medium, the electrochemical properties of the solvent, optional inert electrolyte, anodic materials, cathodic materials, and any other components that might be present in the solution are preferably such that no significant electrochemical or other changes occur at a potential difference which oxidizes anodic material and reduces the cathodic material other than the electrochemical oxidation of the anodic material, electrochemical reduction of the cathodic material, and the self-erasing reaction between the oxidized form of the anodic material and the reduced form of the cathodic material.
In most cases, when there is no electrical potential difference between transparent conductors
14
and
18
, the electrochromic medium
24
in space
26
is essentially colorless or nearly colorless, and incoming light (I
o
) enters through front element
12
, passes through transparent coating
14
, electrochromic containing chamber
26
, transparent coating
18
, rear element
16
, and reflects off layer
20
a
and travels back through the device and out front element
12
. Typically, the magnitude of the reflected image (I
R
) with no electrical potential difference is about 45 percent to about 85 percent of the incident light intensity (I
o
). The exact value depends on many variables outlined below, such as, for example, the residual reflection (I′
R
) from the front face of the front element, as well as secondary reflections from the interfaces between: the front element
12
and the front transparent electrode
14
, the front transparent electrode
14
and the electrochromic medium
24
, the electrochromic medium
24
and the second transparent electrode
18
, and the second transparent electrode
18
and the rear element
16
. These reflections are well known in the art and are due to the difference in refractive indices between one material and another as the light crosses the interface between the two. If the front element and the back element are not parallel, then the residual reflectance (I′
R
) or other secondary reflections will not superimpose with the reflected image (I
R
) from mirror surface
20
a
, and a
Anderson John S.
Bugno Mark D.
Cammenga David J.
Forgette Jeffrey A.
Hall Philip B.
Gentex Corporation
Mack Ricky
Price Heneveld Cooper DeWitt & Litton LLP
Thomas Brandi
LandOfFree
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