Control circuit for an automatic rearview mirror
First Claim
1. An automatic rearview mirror system for a vehicle comprising:
- a reflective element actuatable between at least two different reflective conditions;
a forward light sensor means for sensing light in a direction other than rearward of the mirror;
a rear light sensor means for sensing light rearward of the mirror; and
control circuit means for causing the reflective element to assume a reflective condition as a function of at least the output of said forward and rear light sensor means, said control circuit including modulation means for modifying the output of said forward light sensor means to produce a modified forward light signal and comparison means responsive to the output of said rear light sensor means and said modified forward light signal for indicating the desired reflectance condition of said reflective element as a function of said output of said rear light sensor and said modified forward light signal, wherein said modulation means modifies the output of said forward light sensor means in a manner that reduces the sensitivity of said control means to light rearward of the mirror.
1 Assignment
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Accused Products
Abstract
The invention provides an automatic rearview mirror system (10) for a vehicle comprising a reflective element (22) actuatable between at least two different reflective conditions. The system includes a forward light sensor (11) to detect light forward of the vehicle and a rear light sensor (12) to detect light rearward of the mirror. A control circuit means (14,16) is coupled to the reflective element (22), the forward light sensor (11) and the rear light sensor (12). The control circuit causes the reflective element to assume a reflective state dependent upon the output of the forward and rear light sensors. The control circuit includes means for modifying the output of the forward light sensor (11) to cause a reduction in the sensitivity of the mirror.
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Citations
16 Claims
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1. An automatic rearview mirror system for a vehicle comprising:
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a reflective element actuatable between at least two different reflective conditions; a forward light sensor means for sensing light in a direction other than rearward of the mirror; a rear light sensor means for sensing light rearward of the mirror; and control circuit means for causing the reflective element to assume a reflective condition as a function of at least the output of said forward and rear light sensor means, said control circuit including modulation means for modifying the output of said forward light sensor means to produce a modified forward light signal and comparison means responsive to the output of said rear light sensor means and said modified forward light signal for indicating the desired reflectance condition of said reflective element as a function of said output of said rear light sensor and said modified forward light signal, wherein said modulation means modifies the output of said forward light sensor means in a manner that reduces the sensitivity of said control means to light rearward of the mirror. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An automatic rearview mirror system for a vehicle comprising, a reflective element actuatable between a full reflectance mode in which substantially all incident light striking said reflective element is reflected and a partial reflectance mode in which only a portion of incident light striking said reflective element is reflected, a forward light sensor to detect light forward of the mirror, a rear light sensor to detect light rearward of the mirror, a control circuit means coupled to said reflective element, said forward light sensor and said rearward light sensor, assume one of said reflective modes dependent upon the relationship between the output of said rear light sensor and a sensitivity signal, said control circuit including modulation means for modifying the output of the forward sensor as a function of the reflectance mode of said reflectance element and means responsive to the output of said forward light sensor for establishing said sensitivity signal, wherein said modulation means reduces the sensitivity of the mirror system to light rearward of the mirror when said reflectance element is in said partial reflectance mode.
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16. An automatic rearview mirror system for a vehicle comprising:
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a reflective element actuated between at least two different reflective conditions; a modulating resistor; a forward light sensor means for sensing light in a direction other than rearward of the reflectance element, said forward light sensing means having a parameter that varies in response to light; a rear light sensor means for sensing light rearward of the reflective element, said rearward light sensing means having a parameter that varies in response to light; said forward and rear light sensor means being connected in parallel with one another and in series with said modulating resistor between a pair of supply voltage terminals such that a change in said parameter of said rearward sensor means will modify said parameter of said forward sensor means; means responsive to said parameter of said forward light sensor means for producing a forward light signal; means responsive to said parameter of said rearward light sensor means for producing a rearward light signal; and comparison means for comparing said rearward light signal with said forward light signal and for causing the reflective element to assume a reflective condition as a function of the relationship between said signals.
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Specification