Fault tolerant drive circuit for electrochromic mirror system
First Claim
1. In an electrochromic rearview mirror system for a vehicle having a passenger compartment, said system including at least one exterior electrochromic mirror assembly positioned outside the vehicle passenger compartment, said electrochromic mirror assembly including an electrochromic mirror element and a deicing heater element for removing ice and dew from said electrochromic mirror element during inclement weather, said electrochromic mirror element being responsive to a drive signal that is less than a maximum voltage potential of 1.8 volts to establish the reflectance level of the electrochromic mirror element, said deicing heater element operating at a voltage level of at least approximately 12 volts, a heater supply circuit for supplying one of a vehicle battery voltage and a vehicle ignition voltage to said heater element, and a control system for providing said drive signal to said electrochromic mirror element including at least one electrical conductor to conduct said drive signal to said electrochromic mirror element, comprising:
- desired reflectance level determining means for producing a signal indicative of a desired reflectance level;
output drive means responsive to said desired reflectance level signal for producing said drive signal that is applied to said mirror;
electrical supply means for supplying electrical energy to said output drive means; and
circuit protection means for sensing a foreign voltage on one of said electrical conductors, said foreign voltage being at least approximately 12 volts, and taking corrective action in response to said foreign voltage that prevents said foreign voltage from being applied to said electrochromic mirror element, in order to protect said electrochromic mirror element during repair or replacement of said exterior electrochromic mirror assembly.
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Accused Products
Abstract
A drive circuit for the interior, and one or more of the exterior, mirrors in a vehicle mirror system provides a drive signal to each of the mirrors to establish the reflectance level of that mirror. Circuit protection is provided to sense a fault condition on one of the electrical conductors extending to the exterior mirrors and to take corrective action in response to a fault condition. The circuit protection may also respond to a fault condition in the electrical supply of the drive circuit and take suitable corrective action. In certain embodiments, each mirror in the mirror system is responsive to one of a plurality of output amplifiers, which is responsive to a distinct desired reflectance signal level in order to color that mirror to a reflectance level that is distinct from that of the other mirrors. In other embodiments, separate drive circuits and associated power conditioning means are provided for each mirror so that the disabling of one mirror will not preclude the other mirror(s) in the system from providing glare protection.
93 Citations
50 Claims
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1. In an electrochromic rearview mirror system for a vehicle having a passenger compartment, said system including at least one exterior electrochromic mirror assembly positioned outside the vehicle passenger compartment, said electrochromic mirror assembly including an electrochromic mirror element and a deicing heater element for removing ice and dew from said electrochromic mirror element during inclement weather, said electrochromic mirror element being responsive to a drive signal that is less than a maximum voltage potential of 1.8 volts to establish the reflectance level of the electrochromic mirror element, said deicing heater element operating at a voltage level of at least approximately 12 volts, a heater supply circuit for supplying one of a vehicle battery voltage and a vehicle ignition voltage to said heater element, and a control system for providing said drive signal to said electrochromic mirror element including at least one electrical conductor to conduct said drive signal to said electrochromic mirror element, comprising:
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desired reflectance level determining means for producing a signal indicative of a desired reflectance level; output drive means responsive to said desired reflectance level signal for producing said drive signal that is applied to said mirror; electrical supply means for supplying electrical energy to said output drive means; and circuit protection means for sensing a foreign voltage on one of said electrical conductors, said foreign voltage being at least approximately 12 volts, and taking corrective action in response to said foreign voltage that prevents said foreign voltage from being applied to said electrochromic mirror element, in order to protect said electrochromic mirror element during repair or replacement of said exterior electrochromic mirror assembly. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 29)
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24. In a rearview mirror system for a vehicle having a passenger compartment, said system including a plurality of electrochromic exterior mirrors positioned outside the vehicle passenger compartment, each of said mirrors being responsive to a drive signal to establish the reflectance level of that particular mirror, a control system including electrical conductors for providing one said drive signal to each said mirror, said control system comprising:
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desired reflectance level determining means for producing a signal indicative of a desired reflectance level; drive means responsive to said desired reflectance level signal for producing said drive signal that is applied to each of said mirrors; first and second electrical supply lines for supplying electrical energy to said drive means; fault sensor means for sensing a fault condition on one of said conductors; disconnect means responsive to said fault sensor means for removing electrical energy from said drive means when said fault sensor means senses a fault condition; wherein said fault sensor means includes a current sensor in each of said supply lines for sensing the current on the respective supply line and wherein said disconnect means is responsive to both current sensors in order to remove electrical energy from the drive means when one of the current sensors senses a current that exceeds a predetermined level; and wherein one of said current sensor includes a transistor having an collector-emitter junction between the respective one of said supply lines and said drive means and wherein said disconnect means is responsive to the voltage across said collector-emitter junction exceeding a predetermined level in order to remove electrical energy from said drive means. - View Dependent Claims (25, 26)
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27. In an electrochromic rearview mirror system for a vehicle having a passenger compartment, said system including a plurality of electrochromic exterior mirrors positioned outside the vehicle passenger compartment, each of said mirrors being responsive to a drive signal to establish the reflectance level of that particular mirror, a control system including electrical conductors for providing one said drive signal to each of said mirrors, said control system comprising:
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desired reflectance level determining means for producing a signal indicative of a desired reflectance level; drive means responsive to said desired reflectance level signal for producing one said drive signal that is applied to one of said mirrors; first and second electrical supply lines for supplying electrical energy to said drive means;
fault sensor means for sensing a fault condition on one of said conductors;
disconnect means responsive to said fault sensor means for removing electrical energy from said drive means when said fault sensor means senses a fault condition;
said fault sensor means includes a current sensor in each of said supply lines for sensing the current on the respective supply line; andwherein each of said current sensors includes a resistor between the respective one of said supply lines and said drive means and wherein said disconnect means is responsive to the voltage across said resistor exceeding a predetermined level in order to remove electrical energy from said drive means. - View Dependent Claims (28)
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30. In a electrochromic rearview mirror system for a vehicle including at least one mirror, said mirror being responsive to a drive signal to establish the reflectance level of said mirror, a control system for providing said drive signal to said mirror, said control system comprising:
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desired reflectance level determining means for producing a signal indicative of a desired reflectance level; an output drive means responsive to said desired reflectance level signal for producing said drive signal that is applied to said at least one mirror; electrical energy supply means for supplying electrical energy to said output drive means, said supply means including an input terminal connected with a source of electrical energy and voltage regulating means responsive to said input terminal for regulating the voltage level of the electrical energy supplied to said drive means; said voltage regulating means including first and second power conditioning means electrically serially connected between said input terminal and said drive means, wherein each of said power conditioning means includes a supply voltage input and a regulated voltage output and wherein the supply voltage input of said first conditioning means is connected with said input terminal, the supply voltage input of said second power conditioning means is connected with the regulated voltage output of said first power conditioning means and the regulated voltage output of said second power conditioning means is applied to said drive means; and wherein said voltage regulating means includes voltage reference generating means for generating a first reference voltage and a lower second reference voltage and wherein said first power conditioning means is responsive to said first reference voltage to produce a regulated voltage on its regulated voltage output and said second power conditioning means is responsive to said second reference voltage to produce a regulated voltage on its regulated voltage output. - View Dependent Claims (31, 32, 33)
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34. An electrochromic rearview mirror system for a vehicle having a passenger compartment, including an interior electrochromic rearview mirror positioned inside the passenger compartment and an exterior electrochromic rearview mirror positioned outside the vehicle compartment, each said mirror being responsive to a drive signal to establish the reflectance level of that mirror, and a control system for providing drive signals to said interior and exterior rearview mirrors, comprising:
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a desired reflectance level circuit producing at least one signal indicative of a desired reflectance level; an interior mirror drive circuit responsive to one said signal indicative of a desired reflectance level for producing one said drive signal; interior electrical supply conductors for supplying said one drive signal to said interior mirror in order to establish the reflectance level of the interior mirror; an exterior mirror drive circuit responsive to said at least one signal indicative of a desired reflectance level for producing another said drive signal; exterior electrical supply conductors for supplying said another drive signal to said exterior mirror in order to establish the reflectance level of the exterior mirror; and wherein said interior and exterior supply conductors are isolated from each other and wherein said interior and exterior mirror drive circuits are isolated from each other, so that a fault at said exterior mirror will be isolated from said interior mirror and interior mirror drive circuit.
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35. An exterior electrochromic rearview mirror system for a vehicle having a passenger compartment comprising:
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at least one exterior electrochromic mirror assembly positioned outside said passenger compartment, said at least one mirror assembly including an electrochromic mirror element which colors to a partial reflectance level in response to a coloration voltage signal that is less than a maximum voltage potential of 1.8 volts, a first electrical conductor for supplying said coloration voltage signal to said electrochromic mirror element, a deicing heater element for removing ice and dew from said electrochromic mirror element during inclement weather which operates at a voltage level of at least approximately 12 volts, and a second electrical conductor for supplying one of a vehicle battery voltage and a vehicle ignition voltage to said heater element; and a fault protection circuit which detects a foreign voltage on said first conductor, said foreign voltage being at least approximately 12 volts, and responds to said foreign voltage by preventing said foreign voltage from being applied to said electrochromic mirror element in order to protect said electrochromic mirror element during repair or replacement of said exterior electrochromic mirror assembly. - View Dependent Claims (36, 37, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50)
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38. The exterior electrochromic rearview mirror system in claim 38 wherein said circuit breaker is a quick-acting disconnect device.
Specification