| 摘要 |
Control of multiple hammer elements in a high speed printing system in which the hammer elements are individually operated by energizing pulses applied to electromagnets is effected by an improved regulation circuit with which additional safety features may be used in cooperative fashion. The additive combination of a full wave rectified signal and the voltage level of a storage capacitor which is being charged by the rectified signal is sensed, converted to a lower level, and compared to a voltage reference. A silicon controlled rectifier which controls charging of the storage capacitor is turned on by this circuit only when current is beginning to flow, thus providing the equivalent of zero crossing initiation and preventing high surge currents from developing. As a further feature, signals generated during times at which printing should not be taking place, such as paper advance, are used to alter the voltage reference level so as to effectively turn off the power during the turnaround interval. The voltage reference, whether controlled in this manner or not, is also utilized to govern the coil energizing circuits, so as to prevent energization of the coils in the event of power failure, startup, shutdown and other transient operations.
|
