Brother DCP-8020, Service Manual

Page: 70 / 353

CHAPTER 3 THEORY OF OPERATION
3-14
2.2 Scanner Mechanism
Fig. 3-20
This scanner mechanism supports a dual scanning system.
(1) If you set documents with their faces up on the document chute and start the scanning
operation, the ADF motor rotates so that the document feed roller ASSY feeds those
documents into the ADF unit, starting from the top sheet to the bottom, page by page.
Each then document curves downwards and turns to the right so as to advance above
the CCD unit, and then it is fed out to the document tray with the document ejection roller
ASSY.
This way, documents move above the CCD unit being kept in a stationary position.
(2) If you open the document cover, put a sheet of document (or put a bound book opened)
on the glass of the scanner top cover, close the document cover, and start the scanning
operation, then the CCD drive mechanism will be driven. That is, the CCD motor rotates
and its rotation will be transmitted via the gear train to the CCD drive belt.
The CCD unit, which is supported and guide by the CCD rail, is secured to the CCD drive
belt. Clockwise and counterclockwise rotations of the CCD motor move the CCD unit to
the right and left, respectively.
In this scanning system, the CCD unit moves horizontally beneath a document being
kept in stationary position.
The CCD unit contains a charge coupled device (CCD) image sensor. The cold-cathode
florescent lamp illuminates a document and the reflected light of the scanned image data
is transmitted via the mirrors into the lens which reduces the scanned data so as to form
the image on the CCD.
Top cover
Guide shaft
Front sensor
actuator ASSY
PF roller holder ASSY
ADF cover
LF roller 1 ASSY
Pulley ASSY
Belt
Scanner base
CCD module
HP sensor
Eject roller ASSY
LF roller 2 ASSY