Abstract: A piezoelectric acoustic transducer, especially for a printer photoreceptor toner transfer assist system, having a mechanical resonance varying over a substantial frequency range, is driven by a driver circuit having an automatically variable frequency electrical power output. The driver circuit initially automatically slowly sweeps over a wide frequency range encompassing the resonance range of the transducer until the resonant frequency is detected from the electrical impedance change of the transducer at resonance. The driver circuit then automatically switches to a frequency control with a phase lock loop system responsive to the phase of the transducer voltage and current, to hold and maintain the driver circuit output at the varying resonant frequency of the transducer. A small frequency range rapid dithering of the driver circuit frequency may be additionally provided above and below the resonant frequency of the transducer.

Abstract: A power supply circuit which converts an A.C. signal into an output signal that combines A.C. and D.C. voltages components. The circuit uses a voltage doubler topology with transistors. The transistors are controlled by waveform generators, which generate a series of pulses. By adjusting the duty cycle of the pulses, the appropriate D.C. voltages components can be formed. By adjusting the duty cycle of the positive output producing pulses and negative output producing pulses relative to each other, the required A.C. signal can be adjusted. A scavengeless developer in a xerographic machine requires three bias voltage inputs. The power supply circuit can be attached to a transformer connected to an appropriate A.C. power source to produce the required voltage signals to control the operation of the developer.

Abstract: A charging device for producing a voltage potential on a photoconductive member including a corona generator for charging a portion of the image receptor to a substantially uniform potential; a corona generating potential source electrically connected to the corona generator; a sensor for determining the potential on the image receptor; and a microprocessor including an analog to digital converter interconnected to the corona generating potential source; the sensor; and the controller for regulation of the potential on the image receptor.

Abstract: Method and apparatus for providing multiple colors in a single pass of a copy sheet through a transfer station by switching the polarity of a transfer corotron and automatically adjusting the output of the detac corona device. In particular, a single power supply including high voltage switches responds to color selections to change the polarity of a transfer corotron to charge a copy sheet for toner transfer, and a current sense and precision rectifier stage responds to the copy sheet charge to provide a suitable detac charge independent of the transfer corotron polarity.

Abstract: A resonant circuit sine wave power supply in which the resonant circuit thereof is coupled to ground through alternately conducting complimentary emitter followers during the portions of the voltage generation cycle when the resonant circuit is not coupled to a dc supply, whereby a power supply that is substantially non-dissipative of heat is provided.