Image Transfer Belt Unit; Belt Mark Detection - Ricoh B156 Service Manual

6.7.5 IMAGE TRANSFER BELT UNIT

Drive
[A]: Main motor
[B]: Image transfer belt
[C]: Bottom shaft (rubber
coated)
Main motor [A] Gears
The bottom shaft can drive the transfer belt because of the friction between the belt
[B] and the rubber coating on the shaft [C].
NOTE: The transfer belt and OPC belt contact each other. If you wish to inspect
the transfer belt by turning it, you must also turn the OPC belt at the same
time to avoid damaging the surfaces of the belts.

Belt Mark Detection

[A]: Belt mark sensor
[B]: Mark
The belt mark sensor is a reflective photosensor.
To exactly synchronize the four mono-color toner images on the image transfer
belt, the belt mark sensor [A] monitors the belt speed. The sensor detects the light
reflected by the marks [B] at the rear end of the belt (25 marks per rotation; mark
frequency: 21 mm). The sensor output is used to control the belt speed.
B156/B220
CÓPIA NÃO CONTROLADA
[C]
Bottom shaft [C]
6-38
CÓPIA NÃO CONTROLADA
PHOTOCONDUCTOR UNIT (PCU)
[B]
B156D030.WMF
[A]
B156D314.WMF
[B]
[A]
SM