Abstract: A large-capacity capacitor (C1, C2) is connected in series and/or parallel with a battery (11). A voltage sensor (9, 10) is provided to the battery and/or the large-capacity capacitor to detect their terminal voltages. Input and output currents are limited between at least one of a motor driving circuit and the large-capacity capacitor and the battery on the basis of the detection signals from the voltage sensor. When the terminal voltage of the large-capacity capacitor is equal to or higher than a predetermined value, a current flowing from the motor driving circuit to the large-capacity capacitor is limited.

Abstract: An image sensor of the kind which employs a line array of a-Si photodiodes on an insulating substrate and in which the outputs of the diodes are stored in the lead capacitances until readout. To increase the size of the lead capacitance and thereby to improve the linearity of the ouput, the lead between each diode and its processing circuit is made one plate of a capacitor, of which the other plate is a metal film insulated from the lead and advantageously maintained at ground.