Service manual

CHAPTER 2

2 - 12

2000 CANON INC. CANOSCAN FB1210U REV.0 APR. 2000 PRINTED IN JAPAN (IMPRIME AU JAPON)

A/D Converter

Output

Image Data

+5V

Blue Image Signal

Green Image Signal

Red Image Signal

OFFSET

Reference Voltage

2. D/A Converter

D/A converter removes ununiform analog data generated by the CCD. It adjusts CCD output

to keep max. 5V of input signal to the A/D converter, to make the black level of the image

constant.

3. A/D Converter

The A/D converter converts the black-level-corrected image signal (analog signal) to a 14-bit

image data (digital signal) in the order of red, green and blue image signal.

5V is applied to the VRT terminal and reference voltage is applied to the VRB terminal. A/D

converter outputs “0” when input signal is 5V, and outputs “16383” when input signal is

reference voltage. This converts 1 pixel signal into the image data of 16384 gradations for red,

green and blue each.

Figure 2-11