Motors and fans
The scanner assembly has five motors and two fans. Three of the motors are stepping motors, which
drive the components inside the scanner assembly. The remaining two motors are dc motors, which
drive the two fans.
Name Purpose Type Rotation Failure detection
Carriage motor Drives the carriage unit Stepping motor Varies No
Feed motor Drives the pickup,
separation, and
registration rollers
Stepping motor Varies No
Read motor Drives the feed and
delivery rollers
Stepping motor Counterclockwise No
Flatbed fan Cools the scanner
lamp and the CCD
DC motor Clockwise Yes
ADF fan Cools the motors DC motor Clockwise Yes
Optical assembly
The optical assembly contains the scan carriage and the scanner glass. The scan carriage contains
the lamp, five mirrors, a lens, and the CCD.
Figure 5-39 Scan carriage components
The scanner lamp illuminates a small strip of the document (called the raster line). The mirrors direct
the light through the lens to the CCD. The CCD senses and records the light, creating an analog
representation of the raster line. If the ADF is being used, the document then advances in the ADF to
the next raster line. If the flatbed is being used, the carriage advances to the next raster line. This
advancing and collection process continues to the end of the sheet.
The image data is collected on the scanner controller PCA, where it is processed and sent to the
formatter.
Scanner system 139
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