Xerox PHASER 7500, Service Manual

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Phaser 7500 Printer Service Manual 2-73
Theory of Operation
Toner Supply Control
The Toner Supply Control calculates the toner amount to be supplied based on the
toner density in the Developer, which is detected by the Image Count Dispense
Control (ICDC) Count and the ATC Sensor, in order to maintain the image density.
The toner supply amount is then calculated as the operating time of the Toner
Dispense Motor. Based on the calculated value, just the right amount of toner is
supplied to the Developer Housing Assembly.
Any one of the three modes shown in the table below can be selected by
performing the appropriate settings.
Toner Supply Amount Calculation by ICDC (Image Count
Dispense Control)
The ICDC calculates the toner supply amount based on the number of pixels per
page that is counted by the LPH module.
In the ICDC Toner Supply Mode, only the toner supply amount calculated by the
ICDC is used to perform Toner Supply Control.
Toner Supply Amount Calculation by ATC Sensor
As the Drum/Deve Drive Motor is operating, the ATC Sensor detects the toner
density in the Developer Housing Assembly at regular intervals. At the same time,
the toner supply amount is calculated.
ATC Sensor
The ATC Sensor detects changes in the magnetic permeability that varies
according to the blend ratio of the carrier and toner, and converts the changes into
electrical signals to detect the toner density.
Low ATC Sensor output indicates high toner density, while high ATC Sensor output
indicates low toner density.
Toner Supply Mode
Mode Name Description
Timer Toner Supply Mode A fixed amount of toner is supplied at regular
intervals.
Procon Toner Supply Mode The toner supply amount is calculated and
supplied based on the ICDC count value +
ATC Sensor output value.
ICDC Toner Supply Mode The toner supply amount is calculated and
supplied based on the ICDC count value.