Canon canoscan d660u Service Manual
CHAPTER 2
2 - 16
COPYRIGHT © 2000 CANON INC. CANOSCAN D660U REV.0 JULY 2000 PRINTED IN JAPAN (IMPRIME AU JAPON)
B. Image Processing Functions
1. CCD
The ASIC outputs clock signals based on the command from the host computer to the CCD.
The scanner uses a 3 line CCD to read the color signals. The 3 line CCD is a single chip
photoelectric conversion device which consists of 3 lines of several thousand photosensitive
devices, each several microns square, reading for red, green, and blue analog image signals,
and of a scanning circuit.
The scanner uses a 3 line CCD to read the color signals. The 3 line CCD is a single chip
photoelectric conversion device which consists of 3 lines of several thousand photosensitive
devices, each several microns square, reading for red, green, and blue analog image signals,
and of a scanning circuit.
Figure 2-15
III. IMAGE PROCESSING SYSTEM
A. Outline
The image processing system converts analog image signals read by the CCD into digital
data, performs various image processing, then outputs the data to the host computer via USB
port. Shading correction and gamma correction are performed by the driver software instead of
the scanner function.
data, performs various image processing, then outputs the data to the host computer via USB
port. Shading correction and gamma correction are performed by the driver software instead of
the scanner function.
Figure 2-14
2. A/D conversion
Analog image signals output from the CCD are converted into the digital data of 14 bits each
by A/D converter in the ASIC in order of red, green, and blue image signals.
by A/D converter in the ASIC in order of red, green, and blue image signals.
1. CCD
2. A/D
conversion
5. Resolution
conversion
To host computer
3. Shading
correction
4. Gamma
correction
Blue photosensitive section
Green photosensitive section
Red photosensitive section
Green photosensitive section
Red photosensitive section