Around The Drum; Drum Drive; Phase Control Mechanism - Ricoh G133 Service Manual

PCU (Photo Conductor Unit)

6.4.2 AROUND THE DRUM

Drum Drive

Each PCU has its own drum/development drive motor [A]. The drum/development motor
drives the drum [B] of each PCU.
Also, each drive gear has its own drum gear position sensor [C]. The drum gear position
sensor detects the position of each drum gear, so that the four PCUs are aligned. The
signal from these sensors are used for "Phase Control" as described next. This motor is a
brushless DC motor. This helps to reduce the drive noise.

Phase Control Mechanism

The machine uses the drum gear position sensors to detect if the drum motors rotate.
SC380 shows when it detects that the drum motor is not moving. These sensors also help
the machine to initialize the relative positions of the gears when the main switch is turned
on, and during initializing. This prevents phase fluctuation between printouts that is caused
by incorrect gear meshing at the start of the job.
There is an interrupter on each drum gear. The drum gear position sensors [C] detect the
positions of these interrupters. This mechanism makes sure that output quality does not
vary.
Immediately after the machine power turns on, recovers from the energy saver mode, or
the front door is opened and closed, the machine executes the drum phase adjustment if
one of the following conditions occurs:
When a new PCU is installed.
When a new image transfer belt unit is installed.
Also, if the machine detects a shift in the drum positions during the line position adjustment,
the machine executes the drum phase adjustment.
G133 6-26 SM