Xerox Phaser 6128 MFP, Руководство по обслуживанию

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2-34 Phaser 6128MFP Service Manual
Theory of Operation
Process Control
For stable printing, the parameters related to the image development must be
corrected as necessary. The process control is performed in two methods after
every 25 cumulative prints, upon termination of a print run, or during a continuous
run.
• Potential Control
• Toner Density Control
The following controls supplement the above controls:
• High Area Coverage Mode
• Admix Mode
Potential Control
To attain stable printing image density, the drum charging voltage, the developing
DC voltage, and the Laser Unit beam intensity are adjusted according to the
developing capability of each color carrier that varies momentarily. The adjusted
drum charging voltage, the developing DC voltage, and the Laser Unit beam
intensity are fed back to keep the printing image density constant.
The outline of controls is as follows:
1. The Humidity/Temperature Sensor detects humidity and temperature.
2. The patches of respective colors (Yellow, Magenta, Cyan, and Black) for the
potential control are generated and transferred on the transfer belt.
3. The ADC Sensor (Density Sensor) detects the density of the patch on the Belt.
4. The drum charging voltage, developing DC voltage, and the Laser Unit beam
intensity are adjusted for each color according to the detected patch density.
Toner Density Control
Toner density must be kept constant to attain stable printing. The control system
for this purpose is called toner density control.
1. PCDC (Pixel Count Dispense Control)
The amount of toner to be consumed in the developing process is calculated
by counting the video signals entered to the Laser Unit. The amount of the
toner to be consumed is calculated by the toner dispensing time. The toner
motor is driven for the calculated toner dispensing time when supplying the
toner to the Developer.
2. ADC (Auto Density Control)
The patches of respective colors (Yellow, Magenta, Cyan, and Black) for the
toner density control are generated under a specified potential condition, and
transferred on the Belt. The ADC Sensor measures this density, and the
measured value is compared with reference value. If the toner density is low,
the toner dispense quantity is increased at the next printing, or if the toner
density is higher, the toner dispense quantity is reduced at the next printing.
The toner dispense quantity is calculated by the toner dispense time. This
calculation is made for each color.