Patent ID: 8345397

Claim:
A sensor control apparatus comprising: a signal output section which has a plurality of energization modes for a sensor that is to be connected to the sensor control apparatus, the energization modes including at least a drive mode for supplying electric current to the sensor and a protection mode for stopping the supply of electric current to the sensor to thereby protect the sensor, and which outputs an instruction signal for selecting one of the plurality of energization modes; and a sensor drive circuit for connection to the sensor and which enters one of the plurality of energization modes when the sensor drive circuit receives the instruction signal from the signal output section, so as to control the supply of electric current to the sensor, wherein the sensor drive circuit comprises: detection means for detecting, in the drive mode, an anomaly of the state of electrical connection between the sensor drive circuit and the sensor, protection means, operable when the detection means detects an anomaly of the connection state, for forcing the sensor drive circuit to enter the protection mode irrespective of the energization mode in which the sensor drive circuit has operated, and report means for reporting to the signal output section that the sensor drive circuit is in the protection mode, after the sensor drive circuit is forced to enter the protection mode by the protection means, wherein the signal output section comprises: return means, operable when a report signal outputted by the report means is input to the signal output section, for outputting an instruction signal which instructs the sensor drive circuit to enter the protection mode, and then outputting an instruction signal which instructs the sensor drive circuit to enter the drive mode, and anomaly determination means for determining that an anomaly of the connection state has occurred, if the report signal is again input a predetermined number of times after the sensor drive circuit has entered the drive mode in response to the corresponding instruction signal output from the return means.