Image Quality Control - Toshiba e-STUDIO556 Service Manual

3.12.3

Image Quality Control

[ 1 ] Outline
This equipment performs image quality control with the image quality sensor. Image quality control is
for altering the image formation condition to minimize the changing of the image density and line width
caused by the setting environment for the equipment and the life of consumables.
The image quality sensor detects the density of the test pattern developed on the drum, and the image
formation condition is changed depending on the result.
[ 2 ] Construction
The construction of the control circuit is as follows.
• Image quality sensor:
This sensor emits the light corresponding to the voltage of the light source amount signal output
from the control section onto the drum, and outputs the voltage corresponding to the reflected light
amount of the drum and the test pattern (toner image) on the drum.
• Control section (LGC board):
This section performs image quality control mainly with the engine CPU, which outputs the light
source amount signal (CTDVR-1A) of the image quality sensor by a D/A converter, and converts the
reflected light amount signal (CTDS-1) into a digital signal by mean of the A/D converter embedded
in the engine CPU and reads it, and then sets the image formation condition based on the read
result.
• Image formation process system:
This system consists of the process of charging, laser exposing and developing. Each process is
operated based on the image formation condition set by the control section. When image quality
control is performed, the laser unit exposes the test pattern on the drum.
LGC board
Various image formation conditions
IC58
Engine CPU
Reflected light
amount signal
( CTDS-1 signal )
A/D converter
e-STUDIO556/656/756/856(Ver03)
OUTLINE OF THE MACHINE
IC56
ASIC
Test pattern
Light source amount signal
IC18
( CTDVR-1A signal )
D/A converter
CTDVD-1A
IC12, 98
CTDVC-1A
Operational
amplifier circuit
Fig. 3-43
Image formation process system
Main charger
Drum
Image quality sensor
© 2012 TOSHIBA TEC CORPORATION All rights reserved
3 - 72
Laser exposure
Developing