Reading System; Reading Unit - Canon imageFORMULA P-208 Service Manual With Parts Catalog

CHAPTER 2 FUNCTION & OPERATION
II. READING SYSTEM

1. Reading Unit

The sectional view of the reading units is
shown below. The upper and lower reading
units have the same configuration but the
different shapes for the reading cover each.
Figure 2-201
The upper reading unit reads the back
side of the documents and the lower reading
unit reads the front side of the documents.
This configuration enables the machine to
read both front and back sides of a docu-
ment using a single scan.
The read image data are sent to the
image processing section of the control
PCB.
The reading unit consists of CIS unit,
and reading cover.
The CIS unit consists of CIS PCB, lens
array, LED (R/G/B), light guide, and case.
The reading glass and white reference
sheet are mounted on the reading cover.
2-6
CIS unit
Reading
cover
COPYRIGHT © CANON ELECTRONICS INC. 2012
Photosensitive pixels are mounted on
the CIS PCB with a density of 600 dpi in a
line. The effective reading width is 216 mm,
and the number of effective picture elements
is 5104.
A set of three basic color LEDs, red,
green, and blue (RGB), is mounted only on
the one side. This single-side illumination
causes a shadow on a document, which
may effect on the image data quality.
In the binary or grayscale modes, image
data are read with composite light generated
by lighting the RGB LEDs at the same time.
In the color mode, the LED is successively lit,
and reads image data with each color. As
documents are being fed at regular speed
while image data are read, the reading po-
sitions of RGB are shifted slightly.
CANON P-208 FIRST EDITION