| 摘要 |
PURPOSE:To improve the operability of an entire system by using a signal current for data transmission between a host system and a terminal equipment so as to apply the power for the terminal equipment thereby controlling remotely the power supply for the terminal equipment from a host system. CONSTITUTION:When the power switch 17 of the host system 11 is applied, a drive voltage Vcc from a power supply circuit 16 is fed to a main control section 15, a transmission circuit 13 and a reception circuit 14. When the transmission circuit 13 is in the operating state, one signal line 19b of a couple of signal lines 19a, 19b is kept to the H level state and the other signal line 19a is kept to the L level. Then a potential difference corresponding to the signal level is produced between a couple of the signal lines 19a and 19b and its potential difference is outputted between output terminals of a rectifier circuit 22 to charge a capacitor 23. When the terminal voltage rises up to the specified voltage, a bidirectional semiconductor switching element 24 is activated to conduct exchange terminals, and an AC 100V power inputted from a plug 26 is applied to a power supply circuit 28 via the bidirectional semiconductor switching element 24.
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