Liquid crystal closed-loop controlled mirror systems
First Claim
1. 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 coupling said sensor means and said reference establishing means in electrical control of said optical transmission plate for causing the brightness of the light from the field of view which is incident on said reflecting surface to be 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, said control means comprising an amplifier stage for 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 over said range of possible reference signal levels 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, including observer-settable means settable by the observer to set a desired brightness of light from the field of view which is incident on said reflecting surface and causing said control means to closed-loop regulate the light transmission of said optical transmission plate in correlation with the setting of said observer-settable means, and also including an ambient light sensor means for sensing the prevailing ambient light level and causing said control means to closed-loop regulate the light transmission of said optical transmission plate also in correlation with changes in sensitivity of the observer'"'"'s eyes due to changes in ambient light level, said observer-settable means, said first-mentioned sensor means, and said ambient light sensor means all being in an input circuit relationship to said amplifier stage so as to have an interactive effect on said amplifier stage in performing the closed-loop regulation of said optical transmission plate.
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Accused Products
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 maximum 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 for the observer to set a desired brightness characteristic.
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Citations
39 Claims
- 1. 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 coupling said sensor means and said reference establishing means in electrical control of said optical transmission plate for causing the brightness of the light from the field of view which is incident on said reflecting surface to be 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, said control means comprising an amplifier stage for 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 over said range of possible reference signal levels 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, including observer-settable means settable by the observer to set a desired brightness of light from the field of view which is incident on said reflecting surface and causing said control means to closed-loop regulate the light transmission of said optical transmission plate in correlation with the setting of said observer-settable means, and also including an ambient light sensor means for sensing the prevailing ambient light level and causing said control means to closed-loop regulate the light transmission of said optical transmission plate also in correlation with changes in sensitivity of the observer'"'"'s eyes due to changes in ambient light level, said observer-settable means, said first-mentioned sensor means, and said ambient light sensor means all being in an input circuit relationship to said amplifier stage so as to have an interactive effect on said amplifier stage in performing the closed-loop regulation of said optical transmission plate.
- 17. 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 coupling said sensor means and said reference establishing means in electrical control of said optical transmission plate for causing the brightness of the light from the field of view which is incident on said reflecting surface to be 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, said control means comprising means for 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, 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.
- 25. A variable brightness rearview mirror system comprising a reflecting surface for reflecting a field of view to an observer, an electrically controlled optical transmission plate disposed in the optical path between the field of view and the observer, said optical transmission plate being operable to any of a number of different states of light transmission, sensor means to provide a detection signal sensitive to change in brightness of the field of view incident on the mirror system, control means coupling said sensor means in electrical control of said optical transmission plate for causing the reflected brightness of the field of view seen by the observer to be closed-loop regulated to compensate for changes in the incident brightness, and adjustable correlation means for adjustably correlating the regulated reflected brightness in a manner correlated with changes in the sensitivity of the observer'"'"'s eyes as a function of ambient light level, said adjustable correlation means comprising ambient light sensor means disposed to sense prevailing ambient light from a direction other than the field of view and provide a signal correlated with prevailing ambient light level over a range of different ambient light levels, and means coupling said ambient light sensor means and said first-mentioned sensor in differential input to a high gain amplifier circuit of said control means so that said amplifier circuit provides an output correlated with the differential between signals provided by the two sensor means, and means coupling the output of said amplifier circuit with said optical transmission plate for causing the latter to be operated to a state determined by the amplifier circuit output.
- 33. A variable brightness rearview mirror system comprising a reflecting surface for reflecting to an observer a field of view and an electrically controlled optical transmission plate disposed in the optical path between the observer and the field of view, said optical transmission plate being operable to any of a number of different states of light transmission between a state of maximum transmission and a state of maximum opaqueness, and control means for controlling the brightness of the reflected field of view seen by the observer comprising means for closed-loop regulating the state of light transmission of said optical transmission plate to compensate for changes in incident brightness over a range of different intensities of incident brightness, and said control means further comprising means for selecting a particular range of different intensities of incident brightness, from a number of possible ranges, over which said control means is effective to closed-loop, regulate the state of light transmission of said optical transmission plate, at least some of said number of possible ranges of different intensities of incident brightness having substantially identical spans, said means for selecting a particular range of different intensities of incident brightness comprising ambient light sensor means for at least in part controlling selection of the particular range.
- 38. A variable brightness rearview mirror system comprising a reflecting surface for reflecting to an observer a field of view and an electrically controlled optical transmission plate disposed in the optical path between the observer and the field of view, said optical transmission plate being operable to any of a number of different states of light transmission between a state of maximum light transmission and a state of maximum opaqueness, and control means for controlling the brightness of the reflected field of view seen by the observer comprising means for closed-loop regulating the state of light transmission of said optical transmission plate to compensate for changes in incident brightness over a range of different intensities of incident brightness detected by a sensor means, said control means comprising a high gain differential amplifier circuit receiving a differential input signal derived from differential between a signal correlated with the degree of incident brightness of the field of view and a desired reference signal level, said desired reference signal level serving to establish an operating point of nominal incident brightness on the mirror assembly over a range of nominal incident brightnesses about which said sensor means is effective to exercise control of the optical transmission plate over said number of possible states between maximum light transmission and maximum opaqueness.
Specification