3: Operation
3-70
Colorwriter LSR 2000 Printer
Service Guide
Half-tone correction control
The gate array (IC109) in the DC controller contains a half-tone
correction table used to correct the laser output in order to obtain
the optimum half-tone image. See Figure 3-54 on page 3-70. The
half-tone correction control modifies the half-tone correction table
to accommodate changes in the present environment, the total
number of prints or the condition of the toner and the
photosensitive drum.
The image quality stability control is performed in the following
cases:
•
When the power is turned ON.
•
When the printer encounters an abrupt environmental change.
•
Following a prescribed number of prints.
•
When the toner cartridge is installed or removed.
•
When a new drum cartridge is installed.
In addition, the environment-change correction control is
performed every 30 minutes while the power is turned ON.
Note:
Half-tone correction table
The laser output and the image density of the printer do not change
in a linear relationship.
Therefore, when the laser image is output according to the half-tone
specified by the video data signal sent from the video controller, an
optimum half-tone image would not be obtained on the actual
prints. In order to obtain the optimum half-tone image, the DC
controller is equipped with the half-tone correction table used to
correct the output value of the laser diode.
Figure 3-54
Half-tone correction table
Laser output
Image density
Optimum half-tone curve
Actual half-tone curve