| 摘要 |
<p>PROBLEM TO BE SOLVED: To exactly detect failures in a sensor output measurement value, caused by the increase in the contact resistance between a sensor section and a system control circuit. SOLUTION: The detection device has a pressure sensor 1 for outputting an output voltage that is equivalent to a pressure to be measured, is configured so that a voltage formed by the system control circuit is applied as a supply voltage Vcc of the sensor section, and has a function for changing the supply voltage Vcc applied to the pressure sensor 1 in the system control circuit. The pressure sensor 1 outputs an output voltage that is equivalent to the pressure to be measured, when the supply voltage Vcc is within a prescribed range and outputs a preset voltage that is not related to the pressure when the supply voltage Vcc lies outside the prescribed range. Concretely speaking, in the case of failure diagnosis, a transistor Q1 is turned on by applying a voltage higher than that that in normal occasion, and the output of operational amplifiers OP2 and OP3 for transmitting a pressure signal is set to a low-potential level.</p> |
