Abstract: A copying machine having an optical system movable by a motor in a feed direction with a predetermined feed speed and in a return direction for returning the optical system to a predetermined home position. The optical system is returned with a first speed higher than the feed speed. A countercurrent braking of the motor is performed to decelerate the motor near its home position and the speed of the motor after this braking process is decelerated to such a speed that the optical system can be stopped correctly at the home position.

Abstract: A method of controlling the movement of a lens in a copying apparatus wherein the amount of lens movement is detected and the movement of the lens is corrected if necessary when the lens passes the home position. Even an error in the number of pulses counted before the lens passes the home position can be corrected because of the presence of the home position.

Abstract: This invention generally pertains to a device for electrically detecting a liquid level such as water, oil and so on, which is suitably used for an automatic operating apparatus for a pump, or for a liquid level warning device. The device of the invention comprises an electric heater disposed flush with a liquid level to be detected, a heater temperature detector to electrically detect a heater temperature to generate a heater temperature signal, and an environment temperature detector to electrically detect an environment temperature to generate an environment temperature signal. In one aspect of the invention, there is further provided a reference signal generator to generate a reference signal depending on the range of the environment temperatures at which the liquid level is to be detected, and a comparative circuit to electrically compare a difference between the heater temperature signal and the environment temperature signal to generate a level signal.