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Theory of operation Ver. 1.0 Nov. 2007
21. Image stabilization control
• To ensure that a stabilized output image is produced at all times, a comprehensive con-
trol is provided for the developing bias voltage, laser light intensity, registration correction,
gamma characteristics detection, and other parameters.
21.1 Overview of image stabilization control
• Image stabilization control may be divided into three types: complete correction control,
simplified correction control, and individual registration control. The following explain
specific details of each type of control.
21.1.1
Complete correction control
• Controls 1 through 6 below are collectively called the "complete correction control."
• For details of each of these controls, see the relevant page.
Control name
IDC sensor offset value
check
IDC sensor calibration
1
control
Developing bias Vpp
2
control
Developing bias control
(control of the maximum
3
amount of toner sticking
to the transfer belt)
Laser light intensity con-
4
trol
Gamma characteristics
5
detection control
Registration correction
6
control
To check the low gain output value and offset voltage value of the IDC
sensor when the shutter is closed.
Changes in various types of characteristics due to change with time of
the IDC sensor (deteriorated LED, dirty sensor surface), part-to-part
variations in the sensors, and change of environment affect the IDC Sen-
sor output corresponding to the clear transfer belt surface. To correct
fluctuations in the output, the sensor LED intensity is adjusted so as to
keep constant the IDC sensor output value.
If the developing bias voltage (Vpp) is too high for the Ds distance in
each toner cartridge, a leak image (background leak, image area leak)
results. If Vpp is excessively low, halftone reproducibility becomes poor.
This control detects a Vpp range, in which no image failure occurs, to set
the optimum Vpp.
To correct the target amount of toner sticking to the transfer belt to form
the solid image.
To correct the target level of fluctuations in fine line reproduction and
reverse image (white on black) reproduction that occur due to variations
in photo conductor electrostatic characteristics, developing characteris-
tics, and transfer characteristics (part-to-part variations, environment,
durability).
To correct the tone by using the IDC sensor to measure the density of a
gradation pattern produced on the transfer belt and sending the results
of the measurement to the controller.
To correct incorrect color registration that occurs due to variations in
parts of the main body used for regulating different drawing positions.
21. Image stabilization control
Purpose
83
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