Gestetner B147, Service Manual

Page: 479 / 1081

SCANNING
SM 6-21 B147/B149/B190
Detailed
Des
cription
s
6.3.2 SCANNER DRIVE
The 1st and 2nd scanners [A] are driven by the scanner motor [B] through the
scanner drive pulley, scanner drive shaft [C], and two scanner wires [D].
- Book mode -
The SBU board controls the scanner drive motor. The 2nd scanner speed is half
that of the 1st scanner.
In reduction or enlargement mode, the scanning speed depends on the
magnification ratio. The returning speed is always the same, whether in full size or
magnification mode. The image length change in the sub scan direction is done by
changing the scanner motor speed, and in the main scan direction it is done by
image processing on the IPU board.
Magnification in the sub-scan direction can be adjusted by changing the scanner
motor speed using SP4-008.
- ARDF mode -
The scanners are always kept at their home position (the scanner H.P sensor
detects the 1st scanner) to scan the original. The ARDF motor feeds the original
through the ARDF. In reduction/enlargement mode, the image length change in the
sub-scan direction is done by changing the ARDF motor speed. Magnification in
the main scan direction is done in the IPU board, like for book mode.
Magnification in the sub-scan direction can be adjusted by changing the ARDF
motor speed using SP6-017
B146D508.WMF
[A]
[B]
[C]
[D]