High voltage power supply control apparatus

Abstract

A high voltage power supply controller includes a plurality of high voltage transformers, and causes the high voltage transformers to generate high voltages upon switching operations of corresponding switching transistors, to there by apply the high voltages to loads. The controller includes a plurality of monitor voltage detectors for respectively monitoring changes in high voltages generated in the high voltage transformers, a multiplexer for sequentially selecting monitor voltages from the monitor voltage detectors at predetermined timings so as to supply the selected monitor voltage to a common analog-to-digital converter, an arithmetic operator for comparing a digital value from the analog-to-digital converter with a predetermined reference value and adding a comparison operation result to a feedback value so as to obtain an output value, a plurality of latches for latching arithmetic outputs corresponding to the monitor voltages output from the arithmetic operator and supplying the latched values to the arithmetic operator as the feedback values, a reference counter for counting reference clocks, and an output control circuit for controlling duty ratios for the switching operations of the switching transistors on the basis of a predetermined frequency reference value, the values latched by the latches, and a count value from the reference counter.