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The environmental conditions sensor (PS15) on top of the fan detects the temperature and
the humidity. The PS15 sends this information to the DC controller in the form of the
TEMPERATURE DETECTION signal (TEMSNS) and the HUMIDITY DETECTION signal
(HUMSNS).
The DC controller monitors the environmental conditions of the printer based on these two
signals.
The DC controller controls the following biases to prevent image defects when it detects an
environmental change upon receipt of these two signals.
● Developing bias
● Primary transfer bias
● Secondary transfer bias
If the environment sensor detects a temperature below -30˚ C or over 80˚ C, the DC
controller determines this an "environment sensor abnormality" and sends an error message
to the formatter.
Image density control (D-max)
This control calibrates the value of the developing bias to stabilize the image density.
The DC controller runs the D-max control under the following conditions:
● Power on
● A door is closed after replacement of cartridge
● A specified time has elapsed since the last rotation of the developing cylinder
● A specified amount of environmental conditions has changed since the last image
density control
● A command is received from the formatter
The following is the sequence of this control. (See
Figure 5-56. Image density detection on
the following page.)
1. The DC controller forms 2 lines of density detection patterns (1 line each of the identical
patterns at both sides) in each color on the ITB.
2. The DC controller measures the density of each detection pattern by controlling the color
misregistration sensor. (See
Figure 5-56. Image density detection, on the following page)
3. The DC controller adjusts the developing bias according to the density of the detection
patterns to obtain the correct density.
Image halftone control (D-half)
The control is to measure the halftone density sent from the formatter and send the
measurement back to the formatter so that the formatter can perform an ideal halftone
calibration.
The DC controller controls the D-half, following the sequence below, upon receipt of a
command from the formatter.
The following is the sequence of this control.
1. The DC controller forms each color’s density detection patterns on the ITB according to
the image data received from the formatter, at the best developing bias value adjusted
under the D-max control.
ENWW Image formation system 179