Control arrangement for an occupant restraint system of an automobile
First Claim
1. A control arrangement for the occupant restraint system of an automobile, comprising an acceleration pickup for sensing deceleration of the vehicle and providing an acceleration signal, a trip device in said occupant restraint system, a microcomputer adapted to process said acceleration signal and to supply one or more trip signals to said trip device when the result of processing of said acceleration signal fulfills a criterion for activation of the occupant restraint system, and a monitoring circuit external to said microcomputer and comprising an associated stable oscillator providing a reference signal, said monitoring circuit being adapteda) to monitor as to correct frequency by comparison to said reference signal a check signal derived from a clock signal of said microcomputer;
- b) to produce an enable signal, when said check signal has the correct frequency;
c) to activate an indicating means, when the check signal is found to be incorrect; and
d) in response to the disappearance of said enable signal, to prevent the supply of the trip signal to said trip device.
1 Assignment
0 Petitions
Accused Products
Abstract
The function of a control arrangement for an occupant restraint system in an automobile is continuously monitored by monitoring circuit. The monitoring circuit checks the frequency of a check signal derived from the microcomputer clock signal using a counting device which is controlled by its own stable oscillator. The monitoring circuit supplies an enable signal to the microcomputer, when such frequency is correct. If the frequency of the check signal is not found to be correct the monitoring circuit supplies a drive signal for the operation of an indicating lamp. At the same time the supply of the trip signal to the trip device is prevented. An error message is produced and the trip signal is suppressed also if the monitoring circuit itself fails.
16 Citations
9 Claims
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1. A control arrangement for the occupant restraint system of an automobile, comprising an acceleration pickup for sensing deceleration of the vehicle and providing an acceleration signal, a trip device in said occupant restraint system, a microcomputer adapted to process said acceleration signal and to supply one or more trip signals to said trip device when the result of processing of said acceleration signal fulfills a criterion for activation of the occupant restraint system, and a monitoring circuit external to said microcomputer and comprising an associated stable oscillator providing a reference signal, said monitoring circuit being adapted
a) to monitor as to correct frequency by comparison to said reference signal a check signal derived from a clock signal of said microcomputer; -
b) to produce an enable signal, when said check signal has the correct frequency; c) to activate an indicating means, when the check signal is found to be incorrect; and d) in response to the disappearance of said enable signal, to prevent the supply of the trip signal to said trip device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification