Patent ID: 7796125

Claim:
A voltage supply circuit that switches a first voltage supplied to an electrode to a second voltage, and supplies the second voltage to the electrode, the voltage supply circuit comprising: a first voltage boost circuit including a switching element that generates a third voltage and a fourth voltage that are boosted by a charge-pump operation based on a power supply voltage of the first voltage boost circuit, the fourth voltage being higher than the third voltage; a first selection circuit that selects either the second voltage or the third voltage, the second voltage being obtained based on the fourth voltage; and a charge supply circuit that supplies a charge to the first selection circuit, the first selection circuit supplying the third voltage to the electrode during a first period, the first selection circuit supplying the second voltage to the electrode during a second period, the charge supply circuit supplying the charge to the first selection circuit so as to maintain the voltage of the electrode at the second voltage after the third voltage has been supplied to the electrode, the first voltage being lower than the second voltage, the third voltage just before an ending time of the first period being lower than the second voltage just after a starting time of the second period, the charge supply circuit including an operational amplifier to which a higher-potential power supply voltage of the charge supply circuit and a lower-potential power supply voltage of the charge supply circuit are supplied, the operational amplifier including a first input terminal to which a reference voltage is supplied, and a second input terminal to which a voltage obtained by dividing a voltage between an output voltage of the operational amplifier and the lower-potential power supply voltage of the operational amplifier, and the fourth voltage being the higher-potential power supply voltage of the charge supply circuit.