Patent attributes
In this light beam synchronization detector, an enable circuit 34 outputs a first control signal Se1 to an output circuit 35 when at least one of the absolute values of a voltage signal V1 from a first amplifier 31 and a voltage signal V2 from a second amplifier 32 exceeds the absolute value of a threshold voltage −Vth, thereby putting the output circuit 35 into an operative state. The enable circuit 34 outputs a second control signal Se2 to the output circuit 35 when both the absolute values of the first output voltage V1 and the second output voltage V2 are equal to or lower than the absolute value of the threshold voltage −Vth, thereby putting the output circuit 35 into an inoperative state. This light beam synchronization detector can prevent the occurrence of an error in the detection timing of a light beam due to a change in the quantity of light of the light beam and preventing the occurrence of erroneous detection due to reflected light.
