| 摘要 |
<p>PURPOSE:To make it possible to perform checking even after the mounting on an apparatus by changing the light emitting amount of a light emitting means in response to an external command, comparing the output of a light receiving means with a specified reference value, and changing the specified reference value in response to the external command. CONSTITUTION:When a control signal CONT1 is set at a high level in a current control circuit 6 on the light emitting side, a transistor Tr is turned OFF, and a light emitting element 1 does not emit light. When the CONT1 is set at a low level, the Tr is turned ON, and the element 1 emits light. When a photodetector 2 is ON in a voltage adjusting circuit 8 on the light receiving side, voltage values are inputted into a comparator 3 in response to the voltage dividing ratio among a resistor R6, a variable resistor VR and a resistor R7. When the variable resistor VR is adjusted, the input voltage value into the comparator 3 can be adjusted. When the levels of control signals CONT2 and CONT3 are changed in a reference value control circuit on the light receiving side, the reference voltage of the comparator 3 is changed. Therefore, when the levels of the signals CONT1 - 3 are changed, the checking can be performed by changing the conditions.</p> |
