Phaser 3250 Laser Printer Service Manual 2-27
Theory of Operation
Laser Scanner Unit
The Laser Scanner Unit (LSU) receives image data from the PVC or HPVC
and make latent image on the OPC surface. The LSU uses dual beam
system, LD1 and LD2. The control method of the two beams are the same. In
comparison with a single beam system, dual beam contains half of the LSU’s
frequency.
The LSU consists of laser diode (LD) and the polygon motor control. When
the printing signal occurs, the laser diode is turned On and the polygon motor
is enabled. When the light sensor detects the beam, H-SYNC occurs. When
the polygon motor speed becomes steady, Ready mode occurs. If these two
conditions are satisfied, the Laser Unit is ready. If the two conditions are not
satisfied, one of the two errors are reported as shown in the table below:
LSU Error Recovery
When LReady or H-SYNC error occurs, paper exits from the printer. The
engine mode is changed to recovery mode and the engine checks the LSU
error. When the error stops, print job will continue.
Error Description
Polygon Motor Error
(LReady)
■ When the polygon motor speed is not steady.
■ When printing is started, the engine drives the Polygon
Motor of the LSU. After a specified time is elapsed, if
the motor is not at a Ready status, the engine detects
the error that the Polygon Motor is not Ready.
H-SYNC Error ■ The Polygon Motor speed is steady, but the H-SYNC is
not generated.
■ When the Polygon Motor is Ready, the LSU sends out
the signal called H-SYNC and used to synchronize with
each image line. If the engine does not detect the signal
consecutively for a fixed time, H-SYNC error occurs.
When this error occurs, the engine stops all functions
and keeps it at error state. Red error LED is lit when
error occurs.
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General
Weight and Dimensions
