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Operating Ptinci@es
2.1.2 Carriage Operations
Because photosensor elements are aligned and have a one-to-one correspondence with
row of pixels, no mechanical operation is required for the main scan (one horizontal reading of the
original document). To read more than a single line, however, vertical movement (
also necessary. This requires mechanical movement of the scanner head. In other words, scanning
is performed by reading one line at a time, moving in the vertical direction. The operation is
illustrated in Figure 2-6.
Signal Pixel
Figure 2-6. Reading of an Original Document
The carriage mechanism moves the scanner head. A timing belt is inserted into the base of the
carriage. The carriage motor (a stepping motor) drives the timing belt by means of the carriage
pulley; the carriage moves back and forth along the rail, carrying the scanner head with it. A
home-position sensor detects when the carriage is in the home position.
.
—
Sub-scan(head movement direction)
HP Sensor
/
Figure 2-7. Carriage Operations
Second Line
First
Line
\
\
a horizontal
SU
Scanner Head
Rev. A
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