Patent ID: 7410563

Claim:
A method for preventing corrosion of a contact, the method comprising: comparing a potential of a signal line connected to the contact with a predetermined potential corresponding to the corrosion of the contact, wherein (a) when the potential of the signal line is on one side with respect to the predetermined potential in a magnitude relation, a result of the comparing shows that the contact is corroded; and (b) when the potential of the signal line is on the other side with respect to the predetermined potential in the magnitude relation, the result of the comparing shows that the contact is not corroded; flowing a corrosion-prevention current into the contact when the result of the comparing shows that the contact is corroded; inputting into the signal line a signal used for judging a logical value of a connection state of the contact; and in the magnitude relation, setting the predetermined potential on the other side with respect to a threshold level used in the judging of the logical value of the connection state of the contact, wherein, when the result of the comparing shows that the contact is corroded, a logical value of Hi is outputted; and wherein, when the result of the comparing shows that the contact is not corroded, a logical value of Lo is outputted.