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Original Publication Date: 1981-Dec-31
Included in the Prior Art Database: 2004-Apr-03

Publishing Venue

Xerox Disclosure Journal


High temperatures in xerographic machine photoreceptor drum cavity will cause rapid crystalization damage. A factor causing increased temperature rise is inadequate forced cooling. Most machines have different cooling requirements in standby (only power used to maintain ready state) or in run condition (additional power needed to obtain finished product). One method to obtain the required air flow variation is by control of the number of power cycles a fan drive motor receives using a controller or discrete logic to switch AC power through a triac. In a typical machine, approximately 150 watts is disspated by the fuser in standby and approximately 500 watts during run. The present system provides power cycle controlled fan with one power cycle on and one power cycle off when in standby which is increased to continuous power on during machine operation. Additional benefits of power cycle fan speed reduction in standby are noise reduction, reduced power dissipation by roll fuser and better temperature uniformity axially across roll. Also, air flow and blade speed are very insensitive to line voltage fluctuations, high starting and running torque is provided reducing stall possibility, and it becomes easy to tailor air flow to system requirements by varying the number of cycles deleted and by varying the interval between deleting cycles. The system also allows zero voltage switching to be used thereby reducing turn on noise from inductive motor load, reduces rotor revolutions extending bearing life.