Xerox Corporation

Keith L Bedford

Roger Derek Masham

Krzysztof J Less

Robert Kennedy

David J Meads

Clive R Harris

An apparatus and method are described for extending the life of a photoreceptor in xerographic printing. At a predetermined point in the life span of a photoreceptor, a correction circuit is interposed between the power supply and the charging device of the printer. Correction circuits of different designs can be selected to compensate for the photoreceptor properties at different stages of its useful life. The different correction circuits can be automatically activated over time, or can be retrofitted into a replaceable module when the replaceable module is remanufactured.

System and method for extending the life of a charge receptor in a xerographic printer

A circuit is provided for obtaining precise lamp voltage control and for compensating for varying or fluctuating input from an AC voltage source. The lamp is switched on by a switching device such as a triac. When the triac is powered, a simultaneous powering occurs of a second switching device such as an SCR. The SCR produces a scaled down RMS voltage output which closely matches the actual RMS lamp voltage. This second simulated voltage is precisely controlled in a feedback circuit which includes an RMS to DC converter and a feedback controller. The controller compares a converted DC voltage with a reference voltage and generates a firing pulse to the triac which is advanced or delayed so as to compensate for variations in the AC source as manifested by variations in the converted DC signal relative to the reference signal. Evaluation of the simulated voltage provides the mechanism for precise setting of the converted voltage as a trigger pulse which is generated at the time of the pulse generated by the zero crossing of the AC input.

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Ipswich, United Kingdom

Keith L Bedford