Abstract: A circuit of a detection switch for generating an output signal for driving a load device in accordance with the detection result by a detector is composed with a reduced number of components externally attached to an IC substrate which mounts integrally main circuit units such as a power source circuit unit, a detection circuit unit and an output circuit unit. The output circuit unit comprises a comparator which compares a judgment signal from the detection circuit unit with a reference signal when the load device is driven by DC power, or compares the voltage of an external DC power source with a predetermined voltage when the device driven by AC power, and an output driver which generates a driving signal for the load device in response to the output signal from the comparator. The detection circuit unit produces the judgment signal only when either the output circuit unit or the power source circuit unit is active.

Abstract: A photoelectrical switching circuit, which produces a pulse-modulated light for detecting presence of an object by light interruption or reflection, comprises a frequency divider circuit and a signal output circuit and may comprise a control circuit. The frequency divider circuit includes a counter formed by flip-flops and an operation stop circuit. The counter generates light emission pulse signals with variable period and read pulse signals to pick up light sensing signals and outputting the state of the final stage flip-flop as an operation signal. The operation stop circuit stops the operation of the final stage flip-flop after the operation signal is input. The signal output circuit, which provides output signals after the operation signal is input, includes a shift register for shifting the light sensing signals in step with clock pulses, a set output AND circuit, and a reset output AND circuit.