Patent ID: 7288913

Claim:
A drive wave generation circuit for generating a drive wave for a piezo actuator which is driven by means of a drive wave obtained by combining two types of standard waveforms, the circuit comprising: a standard waveform generation circuit which generates, in accordance with a standard clock, two types of standard waveforms having a constant standard cycle, the two standard waveforms having different duty ratios each denoting a proportion of period during which a specific level is maintained within one cycle, the two standard waveforms further having different timings at which the specific level is maintained; a unit counter which counts each cycle of the standard waveforms, and outputs a unit detection pulse when the counted value reaches a predetermined unit number; a drive counter which advances its count value in a first direction from an initial value according to each input drive pulse, and also advances the count value toward the initial value according to each unit detection pulse from the unit counter; a direction selector which receives input of the two types of standard waveforms from the standard waveform generation circuit, and interchanges, in accordance with a direction control signal, two output terminals from which the received two types of standard waveforms are output; and an output gate which receives the outputs from the direction selector, and, during a period from when the count value of the drive counter is advanced in the first direction to when the count value of the drive counter reaches the initial value, permits supply of those outputs of the direction selector so as to output a drive wave composed of a pair of standard waveforms; wherein the drive wave generation circuit outputs the drive wave composed of a pair of standard waveforms in a number obtained by multiplying a number of the input drive pulses by a number of the standard cycles within one said unit.