Canon CANOSCAN FB330 series Service Manual page 59

The contact image sensor for CanoScan FB330P places 11 phototransistor arrays of 232
light phototransistors each in line, and the contact image sensor for CanoScan FB630P/
FB630U/FB636U place 8 phototransistor arrays of 644 light phototransistors each in line.
Each phototransistor converts the received light into an image signal and outputs the data per
line in series.
Sensor
drive
Image
circuit
signal
output
2. Image scanning operation
When the contact image sensor moves to the image scanning position, the CPU turns the SP
signal to "H" three times per line to light the LED in order of red, green and blue, and reads the
image signal corresponding to each red, green and blue lights. The reading cycle of 1 line is
17.1 msec.
When scanning a grayscale image, only green LED is ON and the image signal is processed.
SP
RLED
GLED
BLED
Image signal
output
COPYRIGHT © 1999 CANON INC. CANOSCAN FB330/FB630 SERIES REV.0 OCT. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
Image signal
Phototransistor Phototransistor
array
Rod lens array
R G B
LED
Figure 2-19
4.2 ms 4.2 ms 4.2 ms 4.5 ms
R G B
Figure 2-20
Phototransistor
array array
R G
CHAPTER 2
Phototransistor
array
B
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