Canon DR-2580C Service Manual page 32

CHAPTER 2 FUNCTION & OPERATION
2. Reading Unit
Figure 2-202 shows the sectional diagram
of the reading unit.
Holder
LED(R/G/B)
Light guide
Case
The reading unit consists of CIS unit,
holder, and lid. The CIS unit consists of CIS
PCB, lens array, LED (R/G/B), light guide, and
case. The reading glass and 2-mm width
shading plate are mounted on the holder.
Photosensitive pixels are mounted on the
CIS PCB with a density of 600 dpi. Effective
reading width is 216 mm, and the number of
effective picture elements is 5104.
Two sets of three basic color LEDs, red,
green, and blue (RGB), are mounted in the
CIS unit. In the binary or grayscale modes,
image data are read with composite light
generated by lighting the RGB LEDs simul-
taneously. In the color mode, the LED is suc-
cessively lit, and reads image data with each
color. As documents are being fed at regular
speed while image data are read, the reading
positions of RGB are shifted slightly.
In the color dropout mode, only the LED of
2-6
Shading plate
Lens array
Figure 2-202
a designated color lights. In the color empha-
sis mode, the LED of a color other than a
designated color lights.
through the light guide.
enters photosensitive pixels through the lens
array, and converted into analog signals cor-
responding to the density of each picture
element.
COPYRIGHT © 2005 CANON ELECTRONICS INC.
Reading glass
CIS PCB
The LED light illuminates the document
The reflected light from the document
CANON DR-2580C FIRST EDITION APR. 2005
LED(R/G/B)
Light guide