| 摘要 |
PURPOSE:To enable for a main unit to detect the connection between the main unit and attached unit only by connecting therebetween by a device wherein the main unit having a control section is equipped with a signal line for detecting the connection and the attached unit controlled by the control section is equipped with a signal line for effecting the detection. CONSTITUTION:A main unit 1 is equipped with signal lines 3-6 and a power line 7 which are connected to a control section 2, while an attached unit 11 is equipped with signal lines 13-17. The signal line 3 serves as a signal line for detecting the connection, to which positive biasing potential preset by a biasing power supply B is applied, and the signal line 13 serves as a signal line for effecting the detection and to cause potential of the signal line 3 to be dropped to the earth potential when connected to the signal line 3. Upon just connecting the main unit 1 and the attached unit 11, the signal line 3 is connected to the signal line 13 so that the potential of the signal line 3 drops from the positive biasing potential to the earth potential. Based on such a change in the potential of the signal line 3, the control section 2 detects the fact that the attached unit 11 is connected to the main unit 1. |
