Filter
Top Products
November 2003 © TOSHIBA TEC 15 - 1 e-STUDIO3511/4511 IMAGE QUALITY CONTROL
15
15. IMAGE QUALITY CONTROL
15.1 General Description
In this equipment, image quality is controlled by the image quality sensor. At this control, image forming
conditions are automatically adjusted so as to minimize the change in the image density or tone repro-
duction caused by the fluctuation of working environment or life of supply items.
At first, the image quality sensor operates to output reflected light amount voltage when no toner image
is formed on the transfer belt. The output voltage is then converted analog-to-digital to be output as the
reflected light amount signal. The light source amount voltage of the sensor is adjusted to correspond
with the value set in advance and the output value of reflected light amount signal at this adjustment is
stored. This output value is considered as the reading of the belt surface. Next, the sensor outputs the
reflected light amount signal when a test pattern is developed on the transfer belt. This output value is
considered as the reading of the toner image.
The difference between the reading of the transfer belt and that of the toner image is defined as toner
adhesion amount. Image forming conditions are determined in approximating this toner adhesion amount
to the value set in advance.
In addition, a shutter operated by the solenoid is equipped on the light receiving/emitting surfaces to
prevent stain to the sensor and to calibrate the sensor with the reflection from the shutter.
15.2 Principle of the Sensor
Image quality sensor projects light onto the transfer belt and the toner image (test pattern) developed on
the transfer belt to output a voltage corresponding to the reflected light amount.
The output voltage is then converted analog-to-digital into reflected light amount signal. The CPU calculates
the toner adhesion amount to control the image forming conditions.
Fig. 15-201
CPU
A/D
D/A
Transfer belt
Test pattern
(toner image)
Light emitting
element
Light receiving
element
Reflected light
amount voltage
Reflected light
amount signal
Light source
amount signal
Light source amount voltage