Patent ID: 8419907

Claim:
A metal ion eluting unit, comprising: a plurality of electrodes; a drive circuit that applies a voltage between the electrodes, such that the metal ion eluting unit elutes metal ions from one of the electrodes serving as a positive electrode by applying the voltage between the electrodes; a control circuit that controls the drive circuit so that the drive circuit periodically reverses a polarity of the voltage applied between the electrodes; and at least one of: (a) a constant-current circuit and a current value setting circuit that control current output from the constant-current circuit and applied to the drive circuit, and (b) a constant-voltage circuit and a voltage value setting circuit that control voltage output from the constant-voltage circuit and applied to the drive circuit, wherein the control unit includes a counter that counts a first predetermined period and a second predetermined period, within a period beginning at a first point in time where the voltage applied between the electrodes changes from one of a negative voltage and a positive voltage to the other of the negative voltage and the positive voltage, and ending at a second point in time, where the polarity changes from the other of the negative voltage and the positive voltage to the one of the positive voltage and the negative voltage, and is configured to operate the drive circuit, from the first point in time until the first predetermined period elapses, in a first current mode, by controlling the at least one of the current value setting circuit and the voltage value setting circuit, in which a value of a current flowing between the electrodes equals a first current value, and operates the drive circuit thereafter in a second current mode until the second predetermined period elapses, by controlling the at least one of the current value setting circuit and the voltage value setting circuit, in which a value of the current flowing between the electrodes equals a second current value smaller than the first current value.