EP0201938A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Liquid crystal controlled mirror systems
Assignee: C-D Marketing Ltd
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Filing: 1986-05-17
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Granted: —
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Expires: 2006-05-17
Abstract
Abstract A rearview mirror system comprises an electrically controlled optical transmission plate disposed over a reflecting surface. The optical transmission plate is selectively operable to any of a number of different states of opaqueness between a miximum light transmission and a maximum opaqueness. The opaqueness of the optical transmission plate is controlled by an electronic circuit which includes two sensors, one for sensing the brightness of incident light from the field of view and the other for sensing ambient light. The control operates to cause the light which is incident on the reflecting surface to be closed loop regulated to a desired degree of brightness which is also correlated with ambient light conditions. A manually operable adjustment is also provided forthe observer to set a desired brightness characteristic.
Inventors
- 👤 Keith D. Jacob
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 22:22
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/1313; B; B60; B60R; B60R1/00; B60R1/02; B60R1/08; B60R1/083; B60R1/088
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
311 words
A variable brightness mirror assembly comprising a reflecting surface for reflecting to an observer a field of view which is incident on the mirror assembly and an electrically controlled optical transmission plate disposed over said reflecting surface, said optical transmission plate being operable to any of a number of different states of light transmission, reference establishing means for establishing any desired level of a reference signal over a range of possible reference signal levels corresponding to a range of different brightnesses for light from the field of view which is incident on said reflecting surface, sensor means disposed to provide a detection signal related to the brightness of the incident field of view on the mirror assembly, and control means operatively coupling said sensor means and said reference establishing means in electrical control of said optical transmission plate such that the brightness of the light from the field of view which is incident on said reflecting surface is closed-loop regulated to a particular level established by said desired reference signal for any intensity of brightness of the field of view incident on the mirror assembly within a range of different intensities of incident brightness on the mirror assembly by said control means causing said optical transmission plate to operate to a state of light transmission which is correlated with both the level of said desired reference signal and the level of said detection signal so as to render the brightness of the field of view incident on said reflecting surface substantially insensitive to change in the incident brightness on the mirror assembly over said range of different intensities of incident brightness for any given level of said desired reference signal while allowing the brightness which is incident on said reflecting surface to be set to any desired brightness within said range of different brightnesses by operation of said reference establishing means.
Claim 2
Dependent Claim
311 words
A variable brightness mirror assembly comprising a reflecting surface for reflecting to an observer a field of view which is incident on the mirror assembly and an electrically controlled optical transmission plate disposed over said reflecting surface, said optical transmission plate being operable to any of a number of different states of light transmission, reference establishing means for establishing any desired level of a reference signal over a range of possible reference signal levels corresponding to a range of different brightnesses for light from the field of view which is incident on said reflecting surface, sensor means disposed to provide a detection signal related to the brightness of the incident field of view on the mirror assembly, and control means operatively coupling said sensor means and said reference establishing means in electrical control of said optical transmission plate such that the brightness of the light from the field of view which is incident on said reflecting surface is closed-loop regulated to a particular level established by said desired reference signal for any intensity of brightness of the field of view incident on the mirror assembly within a range of different intensities of incident brightness on the mirror assembly by said control means causing said optical transmission plate to operate to a state of light transmission which is correlated with both the level of said desired reference signal and the level of said detection signal so as to render the brightness of the field of view incident on said reflecting surface substantially insensitive to change in the incident brightness on the mirror assembly over said range of different intensities of incident brightness for any given level of said desired reference signal while allowing the brightness which is incident on said reflecting surface to be set to any desired brightness within said range of different brightnesses by operation of said reference establishing means.
Claim 3
Dependent Claim
68 words
A variable brightness mirror assembly as set forth in claim 1 in which said reference establishing means includes an ambient light sensor means for sensing the prevailing ambient light connecting. with said control means such that the light transmission of said optical transmission plate is adjusted for changes in ambient light level correlated with changes in the sensitivity of an observer's eyes due to changes in ambient light.
Claim 4
Dependent Claim
55 words
A variable brightness mirror assembly as set forth in claim 1, said control means comprising an electronic control circuit comprising a high gain differential amplifier circuit receiving said reference signal and said detected signal as inputs and providing an output signal which is correlated with the differential of said reference signal and said detected signal.
Claim 5
Dependent Claim
63 words
A variable brightness mirror assembly as set forth in claim 3, said electronic control circuit further including a diode modulator circuit receiving the output of said amplifier circuit and modulating same with a square wave signal from a square wave generator circuit to provide a modulated signal output as an input to a push-pull AC amplifier circuit which drives the optical transmission plate.
Claim 6
Dependent Claim
40 words
A variable brightness mirror assembly as set forth in claim 3, said reference establishing means comprising ambient light sensor means for sensing prevailing ambient light and providing said desired reference signal in correlation with the level of prevailing ambient light.
Claim 7
Dependent Claim
23 words
A variable brightness mirror assembly as set forth in claim 5, including adjustment means for adjusting the gain of said first-mentioned sensor means.
Claim 8
Dependent Claim
35 words
A variable brightness mirror assembly as set forth in claim 6, in which said adjustment means comprises an adjustable device having an operator accessible by the observer for' adjusting the gain of said adjustable device.
Claim 9
Dependent Claim
119 words
A variable brightness mirror assembly as set forth in claim 5 in which said amplifier circuit has a gain G, said ambient light sensor means has a gain K s /N, L R is the intensity of the brightness of incident light from the field of view, L O is the intensity of light incident on the reflecting surface after having passed through the optical transmission plate, L a is the intensity of ambient light on said ambient light sensor, K LCP is a characteristic of the optical transmission plate, and said reference establishing means, said first-mentioned sensor means, said amplifier circuit and said optical transmission plate are organized and arranged such that the following relationships exist: and whereby
Claim 10
Dependent Claim
28 words
A variable brightness mirror assembly as set forth in claim 8 in which the parameter N is variable by an adjustment cooperatively associated with said first-mentioned sensor means.
Claim 11
Dependent Claim
39 words
A variable brightness mirror assembly as set forth in claim 9 in which said adjustment means comprises an adjustment device having an operator accessible to the observer for allowing the observer to manually adjust sensitivity of the control means.
References Cited (Backward Citations)
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