Develop QC 2235 Plus, Service Manual, Page: 115 / 266

QC 2235plus Theory of Operation Ver.1.0 Mar. 2004 Image stabilization control
2-85
II Compos
iti
on/
Ope
ra
tionn
18.2 Operation
18.2.1 Background margin control
• The PC Drum Charge Corona grid voltage (Vg) is set for the pattern based on the infor-
mation provided by the temperature sensor, the PC Drum rotation time, the system
speed, and the target surface potential. The background margin becomes the required
voltage, thereby correcting changes in charging efficiency as a result of a deteriorated
PC Drum and environmental condition changes.
18.2.2 AIDC Sensor LED intensity control
• Controls changes in characteristics due to change with time and contamination of the
AIDC Sensor, part-to-part variations in the sensors, and change of environment.
• The intensity (current value) of the LED is adjusted on the surface of the Transfer Belt, on
which no toner sticks (background level).
18.2.3 Max. density control
• The developing bias (Vb) is adjusted to control changes in the solid density resulting
from variations in developing characteristics and LED intensity, variations in sensitivity of
the PC Drum, and changes in the environment, durability, and the amount of charge in
toner.
• Patterns are produced on the surface of the Transfer Belt and the AIDC Sensor detects
the amount of toner sticking to them.
• The correction data appropriate for each color is selected based on the correction data
with four different levels for each color.
• The developing bias and grid voltage values that result in the maximum density are cal-
culated from the detected data and stored in memory.
18.2.4
γ
correction control
• The intensity of LED in all gradation levels is adjusted to correct changes in gradation
characteristics to a linear one. The changes in gradation characteristics are caused by
variations in the PC Drum sensitivity and developing characteristics and changes with
time and in environment.
• Patterns are produced on the surface of the Transfer Belt and the AIDC Sensor detects
the amount of toner sticking to them.
• The
γ
correction data is calculated using the density measurements of different gradation
levels. The optimum LED intensity is set for each of the different gradation levels.
18.3 Operation timing
*1: Vg and Vb are readjusted if the LED intensity falls outside a predetermined range.
(Mode 3)
Mode Operation Timing
Mode 1 Reset + Stabilizer mode; a new IU is detected; a new Transfer Belt Unit is detected
Mode 2
Stabilizer mode; Left Door is opened and closed; Front Door is opened and closed (IU
removed and reinstalled)
Mode 3
At the end of a print cycle making a given number of printed pages*1; Power Switch is
turned ON; at the end of a print cycle following reset from Sleep; at the end of a print
cycle following an event, in which the interior temperature upper limit threshold value
is exceeded
Mode 4 At the end of a print cycle making a given number of printed pages
Mode 5 Gradation correction