Canon iR8500 - 4-Channels High-Speed CCD

CHAPTER 2 NEW FUNCTIONS
2-75
COPYRIGHT © 2001 CANON INC. 2000 2000 2000 2000 CANON iR8500/7200 REV.1 AUG. 2001
4.3 4-Channels High-speed CCD
To accommodate the reading speed of 80 ipm, a 4-channel high-speed CCD is used. The
CCD consists of two CCDs (half the length of the existing CCD) combined together. The
resulting CCD is divided into the first half and the second half in the middle, and reading is
started at both ends (left/right), thereby reducing the data transfer time needed for reading
by half and ultimately enabling high-speed reading.
The image data comes in four channels: even-number pixels from first half, odd-number
pixels from first half, even-number pixels from last half, and odd-number pixel from last
half. The CCD data is transferred as shown in F02-403-01:
F02-403-01
Direction of charge transferDirection of charge transfer
Direction of charge transferDirection of charge transfer
3750 3749 3748 374737513752375337547500 7499 7498 7497
4 3 2 1
Output
unit A
Output
unit B
Output
unit C
Output
unit D
CCD
shift
pulse
Transfer unit A
Clock pulse BClock pulse D
Clock pulse AClock pulse C
Transfer unit B
Transfer unit C
Transfer unit D
Light-
receiving
unit