Konica Minolta bizhub C658 Service Manual page 1907

bizhub C658/C558/C458/C368/C308/C258
17.2.4 Color registration control (color shift correction)
• Color shift occurs on the tandem engine including image forming units for each color, due to the variations in internal parts and mounting
accuracies. The color registration control system automatically detects color shift and correct color shift in the main and sub scanning
directions.
• The color shift is detected as follows. A pattern is produced at each of front and rear ends of the transfer belt. The IDC sensors at the front
and rear ends read respective patterns to thereby calculate and store color shift amounts in the sub scanning and main scanning directions.
• From data readings, the machine calculates how much the position of each of the different colors should be corrected. Based on the
calculated data, the machine controls each dot during image output, thereby correcting the color shift amount.
17.2.5 Gamma correction control
• The gamma correction value is adjusted to correct changes in gamma characteristics to a linear one. The changes in gamma
characteristics are caused with variations in the photo conductor sensitivity, developing characteristics, durability, environment, and parts
variations in manufacturing.
• It produces gradation patterns on the transfer belt and calculates gradation characteristics output by the current engine with the IDC
sensor.
• An optimum gamma correction value is determined for each color by calculating gamma correction data from the detected data of each of
the colors of C, M, Y, and K.
17.3 Control contents (bizhub C368/C308/C258)
17.3.1 Image stabilization type (mode)
• Six different modes of image stabilization are available.
• A specific mode is selected according to the environmental conditions and print requirements, thereby achieving stabilized image at all
times.
Stabilization type
Mode 1 (initialization and image
stabilization)
Mode 1 (long image stabilization) Executed mainly when there is a change in environmental condition.
Mode 2 (short image
stabilization)
Mode 3 (gamma correction +
color registration control)
Mode 4 (color registration
control)
Mode 5 (monochrome, long
image stabilization)
Mode 6 (monochrome, short
image stabilization)
17.3.2 Control sequence by mode
• A different control sequence applies according to the mode of image stabilization.
• Control is performed in the specified sequence for each mode.
Sequence Mode 1
1 IDC sensor adjustment
2 Dmax density
adjustment
3 LD light intensity
adjustment
4 Color registration
adjustment
5 Dmax density
adjustment
6 LD light intensity
adjustment
7 Gamma correction
• *1: The IDC sensor uses the output value calculated in the last IDC registration sensor adjustment and check that the value measured on
the surface of the transfer belt (background level) is within the specified range. If the measured value is out of the specified range, mode 1
is used when the next image stabilization is carried out.
• *2: Unlike the color registration adjustment of mode 1, simplified color registration control is performed.
• *3: Unlike the gamma correction of mode 1, simplified gamma correction control is performed.
• *4: Monochrome-only mode
17.4 Control contents (bizhub C658/C558/C458)
17.4.1 Image stabilization type (mode)
• Seven different modes of image stabilization are available.
• A specific mode is selected according to the environmental conditions and print requirements, thereby achieving stabilized image at all
times.
O THEORY OF OPERATION bizhub C658/C558/C458/C368/C308/C258 > 17. IMAGE
Executed when "Initialize + Image Stabilization" is selected from the control panel.
Executed mainly after the main power switch is turned ON.
Executed when the count of the number of printed pages during a print cycle reaches 400 and there is a
change in machine interior temperature.
Executed when there is a change in machine interior temperature.
Dedicated to monochrome and executed when there is a change in environmental condition.
Dedicated to monochrome and executed when the number of printed pages during a print cycle reaches
1000 or there is a change in machine interior temperature
Mode 2
IDC sensor
detection *1
Dmax density Color registration
adjustment adjustment *2
Color registration Gamma correction
adjustment *2
Gamma correction
*3
-
-
-
Contents
Mode 3 Mode 4
IDC sensor IDC sensor
detection *1 detection *1
Color registration
adjustment *2
-
*3
- -
- -
- -
- -
O-132
STABILIZATION CONTROL
Mode 5 *4 Mode 6 *4
IDC sensor IDC sensor
adjustment detection
Dmax density Dmax density
adjustment adjustment
LD light intensity -
adjustment
Gamma correction -
*3
- -
- -
- -