PROBLEM TO BE SOLVED: To provide an ultrasonic vibrator driving device capable of stably driving an ultrasonic vibrator accompanied by manufacturing variation in resonance frequency and temperature dependency, while suppressing deterioration in drive efficiency.SOLUTION: The ultrasonic vibrator driving device applies alternation voltage, as drive voltage, to an ultrasonic vibrator containing a piezoelectric element and having a unique resonance frequency, in order to drive the ultrasonic vibrator. The drive voltage is generated to be frequency variable within a frequency range including the resonance frequency of the ultrasonic vibrator. A frequency of the drive voltage is repeatedly swept at a predetermined sweep width including the resonance frequency, and at a predetermined sweep cycle, on the basis of a reference frequency fo set according to the resonance frequency of the ultrasonic vibrator. Furthermore, the sweep cycle and the sweep width are specified in association with each other so that they are included in a predetermined allowable area A on a two-dimensional map divided by sweep cycles and sweep widths.SELECTED DRAWING: Figure 6【課題】共振周波数の製造ばらつきおよび温度依存性を伴う超音波振動子を、駆動効率の低下を抑制しながら安定して駆動できる超音波振動子駆動装置を提供すること。【解決手段】この発明の超音波振動子駆動装置は、圧電素子を含み固有の共振周波数をもつ超音波振動子に対して、駆動電圧として交番電圧を印加して駆動する。駆動電圧を、超音波振動子の共振周波数を含む周波数範囲で周波数可変に発生する。駆動電圧の周波数を、超音波振動子の共振周波数に応じて設定された基準周波数ｆｏを基に、共振周波数を含むように予め定められたスイープ幅で、かつ、予め定められたスイープ周期で繰り返してスイープさせる。これとともに、スイープ周期とスイープ幅とで区分される２次元マップ上で予め定められた許容領域Ａ内に入るようにスイープ周期とスイープ幅とを関連づけて規制する。【選択図】図６
