| 摘要 |
PURPOSE:To form a simple circuit configuration composed of markedly small number of parts; thereby, to ensure to prevent malfunction by providing a noise suppression circuit which is made non-conductive in the case of on/off operations of the power supply, and blocking noises coming out from output ports in an interface circuit. CONSTITUTION:Common signal outputs delivered from the output ports 2-4 are directly fed to each of the interface circuits 35-37 without any intermediate circuit such as open collector ICs. Each interface circuit composed of one transistor and one resistor alone is connected to a noise suppression circuit 38 and, beyond this, to an initial signal generating circuit 13. At the time of noise generation or on/off operations of the power supply, initial signal (a) comes to L level, and accordingly the transistor Q40 of the circuit 38 is on the off condition. The emitter of the transistor Q11 is open as the circuit 38 is non-conductive, and, therefore, noise pulses accompanying signal (c) are blocked by an interface circuit 35, resulting in no noise input to the CR motor 24. The same thing can be said of the LF motor 25 and the printing head 26. |
