| 摘要 |
PURPOSE:To prevent various troubles generated by the connection of an electric circuit in a transient state when insertion and pulling-out are performed, by a method wherein a signal wire is connected to be brought into a continuity state and a power source wire is subsequently connected to be brought into a continuity state at the time of insertion and the power source wire is separated and the signal wire is subsequently separated at the time of pulling- out. CONSTITUTION:Contact pieces 12-14 for the circuit connection of a printing head 1 are provided and the contact pieces 12, 13 are used in a supply wire of a power source and the return wire thereof and the contact piece 14 is used for a printing signal. Each of the contact pieces 12, 13 for the power source is formed so as to be made shorter than the contact piece 14 for a circuit provided in parallel to them. When the printing head 1 is inserted in a receiving port 15, the contact piece 14 is brought into contact with a connection piece 16 at first to perform circuit connection and the contact pieces 12, 13 for the power source are subsequently brought into contact with the connection piece 16 to supply a current to the power source. When the printing head 11 is pulled out from the receiving port 15, reverse order is taken. By this method, an unstable state at a transient time when the power source supply wire and the signal wire are simultaneously connected is avoided and trouble such as the destruction of an element can be prevented. |
