| 摘要 |
<p>PURPOSE:To automatically adjust the sensitivity of a sensor and to execute an alarm display in case of the outside of an adjustment range by correcting the degree of induction to an output of a photodetecting element corresponding to a result of decision of a photodetecting adjustment quantity comparing means for detecting an adjustment value of the photodetecting element. CONSTITUTION:A phototransistor collector current limiting resistance value setting circuit 11 in a sensor 1 is controlled by a micrcomputer 9. An output VCE of the sensor 1 is compared with a reference voltage Tref 4 by a comparator A 5, and compared with a reference voltage Vset 12 by a comparator B 13 installed in parallel to the comparator A 5. Subsequently, to an voltages Vref, Vset of a sensor output level is inputted. Also, to an output of the interface 8, plural pieces of interface terminals are connected in parallel through the current limiting resistance setting circuit 11 in the sensor 1, and a variable resistance VR value for adjusting the sensitivity of the sensor is selected and controlled. In such a way, the sensitivity of the sensor can be adjusted automatically.</p> |
