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June 10th, 1997
DETAILED SECTION DESCRIPTIONS
SCANNER
2.1.2. Scanning
1. Contact Image Sensor
[A]
[B]
[F]
[E]
[D]
[C]
H523D503.wmf
The contact image sensor (CIS) assembly [A] consists of a dust shield [B], a
roof mirror lens array [C], a xenon lamp [D], and an image sensor [E].
The CIS moves under the exposure glass when scanning a book original.
When scanning a sheet original using the ADF, the assembly remains at the
ADF scan line .
The image sensor is a row of 3456 photosensitive elements (400 dpi). The
roof mirror lens array focuses the light reflected from the document onto the
image sensor.
Because of the short optical path inside the CIS, the focal depth is much
shorter than for a CCD type scanner. Because of this, two springs at each
end of the CIS push it against the exposure glass [F], so that the distance
from the original is kept the same all the time.
Because the analog output signal is a sawtooth waveform, data sampling tim-
ing should be adjusted whenever a new CIS is installed in the machine.
2-3
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