Specifications

2.4 Scanner

Figure 2–10 shows the circuits and components within the scanner assembly.

When the printer is powered on, the DC control board generates the scanner

clock ( ) signal that regulates the speed of the scanner motor. The

scanner motor does not run until a print command is received.

When is received, the DC control board asserts the following signals

to turn on the scanner and laser:

• to run the scanner motor

• to enable the laser diode

• to force the laser diode on

When the scanner motor is up-to-speed, the scanner ready ( ) signal

is sent to the DC control board. The following conditions cause a scanner

motor error:

• fails to assert within 20 seconds of .

• negates (goes high) for longer then 2.5 seconds while the

scanner motor is running.

When the scanning beam passes the beam detect (BD) mirror, it reﬂects the

light into the beam detector, creating the signal. The DC control board

receives and sends to the video controller board.

In response to , the video controller transmits the video data out ( )

signal to the DC control board, which sends it to the laser driver as the

signal.

The automatic power control (APC) regulates controls the intensity of the laser

light.

To start the laser the DC control board ﬁrst asserts the signal, then

incrementally increases the value of the APC output ( ) signal. This

action slowly turns the laser on.

When the laser is on, a portion of the laser light strikes the adjacent photodiode

and creates the APC input ( ) signal. feeds back to the DC

control board, which uses it to control and thus stabilize the

intensity of the laser beam.

2–20 Technical Description