Ccd Color Image Sensor; Constant Optical Path Length - Xerox DocuColor 12/DCCS50 Service Manual

CCD Color Image Sensor

The CCD Array is 3 sets of 2 rows of 500 pixels
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.
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DocuColor 12/DCCS50
Figure 5 Constant Optical Path Length
(Figure 6). Each set of pixel rows is filtered to
Refer to Figure 7. Each row of the array acquires its image from the original document in a par-
allel fashion. However, the image is retrieved serially at a 9.97 MHz rate. and passed to the
Pre-IPS 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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Image Sensing (Digital Copier & Copier/Printer
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Principles of Operation