Toner Density Control - Xerox Phaser 6000 Service Manual

Phaser 6000/6010 and WC 6015 MFP

Toner Density Control

The toner density must be kept constant to stabilize the print image quality. The
control system for this purpose is called toner density control.
1. ICDC (Image Count Dispense Control)
The quantity of the toner to be consumed in the developing process is
calculated in terms of toner-dispensing time based on the quantity of the
video signals that have been input to the LPH. The amount of the toner to be
fed to the developer section is controlled by turning on the Toner Motor for the
calculated toner-dispensing time.
2. ADC (Auto Density Control)
The patches of respective colors (Yellow, Magenta, Cyan, and Black) for the
toner density control are generated under the specified potential condition,
and then transferred onto the transfer belt. The ADC Sensor measures the
densities of these patches and compares them with the reference value. If the
toner density is lower than the reference value, the toner dispense quantity is
increased at the next printing. If the toner density is higher than the reference
value, the toner dispense quantity is reduced at the next printing. The toner
dispense quantity is calculated in terms of the toner-dispensing time on a
color-by-color basis.
High Area Coverage Mode
A continuous printing of a high area coverage data that exceeds the extra toner
dispense capability causes the toner density in the developer to be lowered.
The High Area Coverage Mode postpones the next page feed and dispenses the
toner during this time if the toner dispense time has reached the specified value
during a continuous printing.
Admix Mode
This mode executes extra toner dispensation to prevent the toner density from
being lowered whenever the value of the toner density control patch measured by
the ADC Sensor falls far below the reference value. If the toner density level cannot
be recovered even after this operation, it is determined that the toner has run out.
ADC Sensor Adjustment
The ADC Sensor is a reflection type sensor that irradiates the light from its LED
onto the target and detects the reflected light at its photoreceptor and outputs
electric signals responsive to the amount of detected light. To ensure an accurate
patch density measurement, the surfaces of the ADC Sensor is cleaned to remove
soil due to toner, etc., and the light quantity adjustment is made so that the
reflected light quantity satisfies the predetermined value when the patch for
potential control and toner density control are created.
Xerox Internal Use Only
Theory of Operation
2-65