Konica Minolta bizhub C658 Service Manual page 1906

bizhub C658/C558/C458/C368/C308/C258
17. IMAGE STABILIZATION CONTROL
17.1 Overview
• The machine provides the following image stabilization control to ensure stabilized copy image.
Purpose
To stabilize image density
To stabilize gradation
To stabilize toner density
To stabilize image transfer
Toner supply motor
Color skew
correction
PH temperature
sensor
TCR sensor
Toner supply control
Image density
Gradation control
Gamma correction data
Gradation correction table
OUT/IN
· To be set on control panel
D MAX density
Background voltage margin
ATDC toner supply
17.2 Description of control
17.2.1 IDC sensor adjustment control
• Controls changes in characteristics due to change with time and contamination of the transfer belt and IDC sensor, part-to-part variations in
the sensors, and change of environment.
• The intensity (current value) of the IDC sensor is adjusted on the surface of the transfer belt, on which no toner sticks (background level).
17.2.2 Max. density adjustment control
• The developing bias (Vdc) is adjusted to control changes in the solid density resulting from variations in developing characteristics and IDC
sensor intensity, variations in sensitivity of the photo conductor, 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 IDC sensor detects the amount of toner sticking to them.
• Referring to the detected data and the environment data taken by the temperature/ humidity sensors, the developing bias value that results
in the appropriate maximum density is calculated and stored in memory.
• Thereafter, the grid voltage (Vg) value, including the background margin adjustment value, is calculated and stored in memory.
17.2.3 LD intensity adjustment control
• It adjusts the variation in reproducibility of the thin line and the reverse outline, which is resulting from the variations in electrostatic
characteristics of the photo conductor, developing characteristics and transfer characteristics in terms of individual difference, environment
and durability, to make it the target level.
• It produces detection patterns on the surface of the transfer belt with the given level of LD intensity and detects the output value of IDC
sensor.
• LD intensity is calculated from the detected IDC sensor data.
O THEORY OF OPERATION bizhub C658/C558/C458/C368/C308/C258 > 17. IMAGE
Control
IDC sensor adjustment control
Max. density adjustment control
LD intensity adjustment control
Registration control (color shift correction)
Gamma correction control
TCR control (Y, M, C, K)
Transfer output control
Transfer ATVC
PC PC
PC
PC
drum drum drum
drum
M
Y C
G2/Y G2/M G2/C
Developing bias Vdc Charge voltage Vc
Temperature/
humidity sensor
K
IDC sensor
Transfer ATVC control
IN
OUT
O-131
STABILIZATION CONTROL
Control means
IDC sensor
Temperature/humidity sensor
PH temperature sensor
TCR sensor
Temperature/humidity sensor