| 摘要 |
PURPOSE:To obtain an interface circuit which prevents a load for an operational apparatus from being destroyed when a printer apparatus is connected to the optional apparatus. CONSTITUTION:A first apparatus which is provided with power supplies E1, E2 is connected to a second apparatus which is provided with loads 21, 22 which correspond respectively to the power supplies E1, E2. In the second apparatus, bypass capacitors are connected in parallel with the respective loads 21, 22, signal-ground terminals for the respective loads 21, 22 are connected to a signal ground SG1 for the first apparatus via a signal ground SG2 for the second apparatus, and a frame ground FG1 for the first apparatus and a frame ground FG2 for the second apparatus are connected to the signal ground SG1 for the first apparatus. A diode D is arranged and installed across the signal ground SG2 and the frame ground FG2 in the second apparatus, its anode is connected to the signal ground SG2, and its cathode is connected to the frame ground FG2. |
