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DocuColor 12/DCCS50
Image Sensing (Digital Copier & Copier/Printer
Principles of Operation
Reissue
Figure 5 Constant Optical Path Length
CCD Color Image Sensor
The CCD Array is 3 sets of 2 rows of 500 pixels (Figure 6). Each set of pixel rows is filtered to
detect a different color: red, green and blue. The two rows within each set are offset by.0025
inches (0.0635 mm), permitting the array to gather two lines of data at once. The sensor can
scan a document 12.5 inches wide.
Refer to F
igure 7. Each row of the array acquires its image from the original document in a par-
allel f
ashion. However, the image is retrieved serially at a 9.97 MHz rate. and passed to the
Pre-I
PS PWB. While an image is being shifted out, the CCD array cannot acquire another
image. In addition, image acquisition takes time, reducing slightly the image line acquisition
rate. However, having two CCD rows per color doubles the image line acquisition rate. Further-
more, the image acquisition line rate must be the same as the rate at which the Full-Rate Car-
riage sweeps the document original (225 mm/
sec.
[8.858 inches/second] at 100%
magnification) X the desired pixel rate (400 pixels/inch or 15.748 pixels/mm). The end result is
that the CCD acquires image lines, in all three colors, at a rate of 3543.3 per second.
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