Fault detection device for an automotive passenger protection device
First Claim
1. A fault detection device for an automotive passenger protection device, comprising:
- a DC power source;
first and second starting means, each including a resistor, coupled in parallel circuit relationship to each other, said first and second starting means being coupled across said DC power source;
at least one acceleration sensor coupled in series with said first and second starting means and including a first resistor having a resistance greater than a resistance of each of said resistors of said first and second starting means; and
a normally open contact coupled in parallel with said first resistor;
wherein said normally open contact is closed upon detection of an impulse above a predetermined magnitude, thereby supplying a current above a predetermined level from said DC power source to said first and second starting means to start a passenger protection device;
a differential amplifier having a non-inverting input terminal and an inverting input terminal coupled across said first and second starting means;
a judgment circuit means coupled to an output of said differential amplifier for determining an occurrence of failure of said first and second starting means on the basis of an amplified output voltage of said differential amplifier;
a diode having an anode and a cathode coupled across respective higher voltage terminals of said first and second starting means;
a second resistor having a resistance equal to the resistance of said first resistor, said second resistor being inserted across a positive terminal of said DC power source and the cathode of said diode;
first and second switching means inserted respectively between the respective higher voltage terminals of said first and second starting means and the non-inverting input terminal of said differential amplifier; and
means for alternately turning on said first and second switching means, such that the non-inverting input terminal of said differential amplifier is supplied alternately with a voltage from said respective higher voltage terminals of said first and second starting means.
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Accused Products
Abstract
A fault detection device for an automotive passenger protection device includes a pair of parallel-connected squibs 4a and 4b coupled across a DC power source 1 and acceleration is sensors 3 and 5 coupled in series therewith. A diode 10 coupled across the higher voltage terminals of the two squibs, and field effect transistors 30 and 31, inserted between the non-inverting input terminal of the differential amplifier 7 and the measurement points A and A'"'"', are driven alternately by the judgment circuit 8. A resistor 20 balances the voltages at the measurement points A and A'"'"' when the normally open contacts 3b and 5b are open. When the normally open contacts 3b and 5b are open, the voltages at measurement points A and A'"'"' are supplied alternately to the differential amplifier 7, so that the failures of the two squibs can be detected individually.
35 Citations
4 Claims
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1. A fault detection device for an automotive passenger protection device, comprising:
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a DC power source; first and second starting means, each including a resistor, coupled in parallel circuit relationship to each other, said first and second starting means being coupled across said DC power source; at least one acceleration sensor coupled in series with said first and second starting means and including a first resistor having a resistance greater than a resistance of each of said resistors of said first and second starting means; and
a normally open contact coupled in parallel with said first resistor;
wherein said normally open contact is closed upon detection of an impulse above a predetermined magnitude, thereby supplying a current above a predetermined level from said DC power source to said first and second starting means to start a passenger protection device;a differential amplifier having a non-inverting input terminal and an inverting input terminal coupled across said first and second starting means; a judgment circuit means coupled to an output of said differential amplifier for determining an occurrence of failure of said first and second starting means on the basis of an amplified output voltage of said differential amplifier; a diode having an anode and a cathode coupled across respective higher voltage terminals of said first and second starting means; a second resistor having a resistance equal to the resistance of said first resistor, said second resistor being inserted across a positive terminal of said DC power source and the cathode of said diode; first and second switching means inserted respectively between the respective higher voltage terminals of said first and second starting means and the non-inverting input terminal of said differential amplifier; and means for alternately turning on said first and second switching means, such that the non-inverting input terminal of said differential amplifier is supplied alternately with a voltage from said respective higher voltage terminals of said first and second starting means. - View Dependent Claims (2, 3, 4)
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Specification