| 摘要 |
PURPOSE:To achieve effects on reducing cost, reducing size, enhancing reliability or the like by which heat loss in a driving circuit can be reduced, by varying the printing impact of a hammer solenoid through regulating the duty of a chopper pulse. CONSTITUTION:An oscillating circuit (c) constantly oscillates a chopper pulse, and when a driving pulse signal (a) is applied to the input, a monostable multivibrator (b) generates a pulse with a fixed width, and resets it to the oscillating circuit (c) to suspend oscillation for this period. When the output pulse from the multivibrator (b) disappears, to circuit (c) restarts oscillation. An output pulse from the multivibrator (b) and the chopper pulse from the circuit (c) are supplied to the input of an OR gate (e), and an output therefrom and the driving pulse signal (a) are supplied to the input of an AND gate (d), whereby a synthesized driving pulse is obtained at the output of the AND gate (d). The synthesized driving pulse is applied to a base of a transistor Tr through a resistor R1 to energize the hammer solenoid SOL. |
