Indicator energizing monitor circuit for anti-skid brake control systems and the like
First Claim
1. A monitor circuit for monitoring detection of a fault condition or the like to control energization of an indicator, comprisingpower supply means for supplying electric power to the monitor circuit,output circuit means for controlling energization of the indicator,timer circuit means for operating said output circuit means each time said power supply means powers up the monitor circuit to energize the indicator for a predetermined duration and thereafter while said power supply means continues to supply electric power to the monitor circuit to maintain the indicator de-energized,input circuit means for bypassing said timer circuit means upon receipt of an input signal indicative of detection of a fault condition or the like to operate said output circuit means for energization of the indicator to indicate such detection, andsaid timer circuit means including delay means for delaying completion of such bypassing of said timer circuit means to preclude inadvertent energization of the indicator in response to electrical noise signals received by said input circuit means.
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Accused Products
Abstract
A monitor circuit coupled to an anti-skid brake control system or the like has as one function the energization of a warning lamp each time the system is powered-up and as a second function the energization of that lamp when a fault is detected in the system. The invention relates to improvements in such a monitor circuit, including a delay mechanism to preclude inadvertent energization of the warning lamp in response to electrical noise signals, for example, that are common in a vehicle, and a protective mechanism to prevent destruction of parts of the monitor circuit if the output terminals thereof coupled to the warning lamp are short circuited.
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Citations
15 Claims
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1. A monitor circuit for monitoring detection of a fault condition or the like to control energization of an indicator, comprising
power supply means for supplying electric power to the monitor circuit, output circuit means for controlling energization of the indicator, timer circuit means for operating said output circuit means each time said power supply means powers up the monitor circuit to energize the indicator for a predetermined duration and thereafter while said power supply means continues to supply electric power to the monitor circuit to maintain the indicator de-energized, input circuit means for bypassing said timer circuit means upon receipt of an input signal indicative of detection of a fault condition or the like to operate said output circuit means for energization of the indicator to indicate such detection, and said timer circuit means including delay means for delaying completion of such bypassing of said timer circuit means to preclude inadvertent energization of the indicator in response to electrical noise signals received by said input circuit means.
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7. A monitor circuit for monitoring detection of a fault condition or the like to control energization of an indicator, comprising
power supply means for supplying electric power to the monitor circuit, output circuit means for controlling energization of the indicator, timer circuit means for operating said output circuit means each time said power supply means powers up the monitor circuit to energize the indicator for a predetermined duration and thereafter while said power supply means continues to supply electric power to the monitor circuit to maintain the indicator de-energized, said timer circuit means including a resistor and a capacitor connected in series circuit, input circuit means for bypassing said timer circuit means upon receipt of an input signal indicative of detection of a fault condition or the like to operate said output circuit means for energization of the indicator to indicate such detection, said input circuit means including a discharge circuit coupled in parallel with said capacitor to discharge the same, said discharge circuit including a transistor, and said timer circuit means including delay means for delaying completion of such bypassing of said timer circuit means to preclude inadvertent energization of the indicator in response to electrical noise signals received by said input circuit means, said delay means including resistor means coupled in said discharge circuit in series relation with said transistor for delaying such discharging of said capacitor.
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9. A monitor circuit for monitoring detection of a fault condition or the like to control energization of an indicator, comprising
power supply means for supplying electric power to the monitor circuit, output circuit means for controlling energization of the indicator, said output circuit means including a comparator amplifier, a transistor switch coupled to said comparator amplifier and biased to conduction by said comparator amplifier when the input voltage to the latter exceeds a predetermined amplitude, and impedance means coupled in series circuit relation with respect to said transistor switch to limit electrical power surges thereto, timer circuit means for operating said output circuit means each time said power supply means powers up the monitor circuit to energize the indicator for a predetermined duration and thereafter while said power supply means continues to supply electric power to the monitor circuit to maintain the indicator de-energized, said timer circuit means including a resistor and a capacitor connected in series circuit, input circuit means for bypassing said timer circuit means upon receipt of an input signal indicative of detection of a fault condition or the like to operate said output circuit means for energization of the indicator to indicate such detection, said input circuit means including a discharge circuit coupled in parallel with said capacitor to discharge the same, and said timer circuit means including delay means for delaying completion of such bypassing of said timer circuit means to preclude inadvertent energization of the indicator in response to electrical noise signals received by said input circuit means, said delay means including resistor means coupled in said discharge circuit in series relation with said transistor for delaying such discharging of said capacitor.
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14. A monitor circuit for monitoring detection of a fault condition or the like to control energization of an indicator, comprising
power supply means for supplying electric power to the monitor circuit, output circuit means for controlling energization of the indicator, timer circuit means for operating said output circuit means each time said power supply means powers up the monitor circuit to energize the indicator for a predetermined duration and thereafter while said power supply means continues to supply electric power to the monitor circuit to maintain the indicator de-energized, input circuit means for bypassing said timer circuit means upon receipt of an input signal indicative of detection of a fault condition or the like to operate said output circuit means for energization of the indicator to indicate such detection, said timer circuit means including delay means for delaying completion of such bypassing of said timer circuit means to preclude inadvertent energization of the indicator in response to electrical noise signals received by said input circuit means, and said output circuit means including a comparator, and said timer circuit means including capacitor means for passing an electrical signal of sufficient magnitude to said comparator upon energization of the monitor circuit to effect operation of the latter to energize the indicator until said capacitor means charges to a predetermined voltage.
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15. A monitor circuit for monitoring detection of a fault condition or the like to control energization of an indicator, comprising
power supply means for supplying electric power to the monitor circuit, output circuit means for controlling energization of the indicator, said output circuit means including electrical terminals to which the indicator is electrically connected, transistor switch means for completing a circuit path to said terminals to energize the indicator, and impedance means for limiting the amplitude of a power surge to said transistor switch means upon short circuiting of said electrical terminals, said impedance means including a self-heating resistor having a resistance that increases with increasing temperature, timer circuit means for operating said output circuit means each time said power supply means powers up the monitor circuit to energize the indicator for a predetermined duration and thereafter while said power supply means continues to supply electric power to the monitor circuit to maintain the indicator de-energized, input circuit means for bypassing said timer circuit means upon receipt of an input signal indicative of detection of a fault condition or the like to operate said output circuit means for energization of the indicator to indicate such detection, and said timer circuit means including delay means for delaying completion of such bypassing of said timer circuit means to preclude inadvertent energization of the indicator in response to electrical noise signals received by said input circuit means.
Specification