| 摘要 |
PURPOSE:To provide the self-diagnosis function of a sensor to a sensor part, by checking the principal function part in the sensor and detecting the abnormality of the function of the sensor on the basis of the presence of an abnormal signal due to the check result in the side of a control part. CONSTITUTION:When abnormality is generated in at least either one of the light emitting circuit, input circuit 7, detection circuit 9 and output circuit 11 as the principal function parts in a sensor, the abnormal signal receives reversal processing by an inverter to be inputted to a first AND circuit 17. Therefore, the AND output signal of the first AND circuit 17 becomes 0 and the output signal of the second AND circuit 20 of the next stage also becomes 0 and, therefore, the live pulse P0 from a frequency divider 21 is interrupted. As a result, the amplitude of the integral wave form at the time of abnormality comes to a level equal to or more than the S-level of a first Schmitt circuit 25 and an abnormal signal is outputted from an abnormality detection circuit 27.
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