Abstract: A voltage to pulse-width conversion circuit includes a counter which counts a reference frequency signal and produces a multi-bit digital value; a digital/analog converter which converts the digital value into an analog signal; and a voltage comparator which compares an output of the digital/analog converter with a control signal and produces a pulse width modulated output signal which has a predetermined duty cycle ratio.

Abstract: A current driving circuit including a CMOS inverter, a Darlington amplifier, and a semiconductor switch, enables a printing head to be operated with low power consumption. The Darlington amplifier having a plurality of bipolar transistors is connected to an output part of the CMOS inverter. The semiconductor switch, which is connected to the Darlington amplifier, controls the bias voltage of the Darlington amplifier in synchronism with an input signal inputted to the CMOS inverter.

Abstract: A pulse width control circuit for providing a control signal to adjust variations of electrical characteristics among a plurality of printing elements has an up/down counter and a plurality of control signal generating circuits. The up/down counter counts the number of pulses of a clock signal and delivers the counted value. The control signal generating circuit compares the counted values from the up/down counter with set values corresponding to conduction time periods of the currents used for driving light emitting diodes, and generates a plurality of control pulse signals having pulse widths whose central positions thereof are in accord with each other.

Abstract: In a motor control system including a clock pulse generator, use is made of the clock pulses for deriving digitally, the speed-above-normal signal, the starting signal, the brake-release signal and the normal or forward rotation signal for displaying the normal or forward rotation. In response to the starting signal, 100% torque control voltage is generated and in case of the forced reversal in rotation, 100% torque control voltage for preventing the rotation in the reverse direction is generated.