Current mirror seatbelt interface circuit
First Claim
1. A passenger safety interface circuit comprising:
- a current mirror circuit having first and second current paths, a seatbelt latch sensor circuit in said second current path, a current sensing circuit in said first current path, said first current in said first current path mirroring the current in said second current path, and a control microprocessor circuit responsive to the current in said first current path for controlling the activation of a passenger safety system.
1 Assignment
0 Petitions
Accused Products
Abstract
A current mirror seatbelt interface circuit and method for accurately determining seatbelt latch status in a passenger vehicle safety system. By the use of a current mirror circuit, the current through the seatbelt latches can be accurately determined. This determination is used to activate (if the seatbelts are buckled) or inactivate (if the seatbelts are unbuckled) the safety protection systems including passenger airbags and seatbelt tensioners. The current through the seatbelt latch sensor is mirrored through the circuit herein disclosed. The mirrored current is monitored and the current value is analyzed by an airbag control microprocessor circuit to activate or inactivate the safety system. Parallel wired matching transistors in conjunction with a control transistor accurately provide the mirrored current information to the microprocessor. In addition, multiple seatbelt latch sensors can be connected to the current mirror by adding control transistors for each additional seatbelt latch.
44 Citations
11 Claims
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1. A passenger safety interface circuit comprising:
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a current mirror circuit having first and second current paths, a seatbelt latch sensor circuit in said second current path, a current sensing circuit in said first current path, said first current in said first current path mirroring the current in said second current path, and a control microprocessor circuit responsive to the current in said first current path for controlling the activation of a passenger safety system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of monitoring the status of passenger vehicle seatbelt latches comprising:
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providing a current mirror circuit with first and second current paths, controlling the current flow in said second current path by a control microprocessor circuit, monitoring the status of the seatbelt latches by providing a seatbelt latch sensor circuit, measuring the current in said first current path, said current in said first current path mirroring the current flow in said second current path, applying the measured current to the control microprocessor circuit to provide the status of the seatbelt latches to the microprocessor circuit, and providing an output path from said microprocessor circuit to a vehicle airbag system and/or a vehicle seatbelt tensioner system to fire or not to fire depending on the status of the seatbelt latches in the event of a detected collision or sudden deceleration.
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10. A method of monitoring the status of passenger seatbelt latches comprising:
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providing a current mirror circuit with first and second current paths, said passenger seatbelt latches being included in the second current path, mirroring the current in said second current path in said first current path, measuring the current in said first current path, applying the measured current to a control microprocessor circuit, and controlling the activation of a vehicle airbag system and/or a vehicle seatbelt tensioner system to enable or disable firing depending on the status of the seatbelt latches in the event of a detected collision or sudden deceleration. - View Dependent Claims (11)
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Specification