In a constant current circuit that supplies a constant current Ic to a circuit connected to a current output terminal, the first transistor M1 is disposed on a current path of the constant current Ic. A new reference signal to which each of the two reference sources are phase locked, and has frequency n times the respective reference signal, is generated. The sealing membrane is fixed in the valve housing by the valve insert that includes a valve plunger for opening and closing the sealing membrane by movement in a first direction. The plurality of control gears receives the commands from the control device and control lighting. The noise subtraction function subtracts the noise detected by the sub detector from the signal detected by the main detector to remove or reduce the noise from the signal.