| 摘要 |
PURPOSE:To provide an electric power supply device by which the occurrence of noise can be restrained by setting on-duty at 1:1 in simple circuit constitution. CONSTITUTION:On and off driving is carried out alternately on the first and the second transistors Q11 and Q12 in a half bridge type inverter circuit 12. Voltage is induced in a coil L12a by means of electric current oscillation of the second oscillation circuit 14, and in the case of positive bias, the first timer circuit 15 is triggered, and prescribed time is measured, and in the case of negative bias, the second timer circuit 16 is triggered, and prescribed time is measured. Since the first and the second transistors Q11 and Q12 are turned off forcedly respectively by means of transistors Q13 and Q14 according to output of the first and the second timer circuits 15 and 16, on-duty of the first and the second transistors Q11 and Q12 can be set at 1:1. Since an output electric current is made symmetrical in both the positive and the negative, a sinusoidal wave in which a higher harmonic component is small can be formed, so that the generation of noise can be prevented. |
