Toshiba e-STUDIO167 Service Manual page 102

Optoelectronic conversion
As in the same manner as the minification optical systems in other equipments, the CCD of the contact
image sensor (CIS) unit in this equipment performs photoelectronic conversion and charge transfer by
the combination of its shift registers and photodiodes (light-receiving sensors) to output signals for a pri-
mary scanning direction.
Pixels of 24.0 Pm (primary scanning direction) x 40.0 Pm (secondary scanning direction), which can be
scanned by 1 light-receiving sensor, are arranged at 42.3 Pm intervals in this 1:1 magnification optical
system CIS. In the CCD, 1 chip consists of 644 pixels and 1 channel consists of 3 chips (only the chan-
nel 4 consists of 2 chips), and 1 line of a primary scanning direction consists of 4 channels, as shown in
the figure below.
Each light-receiving sensor photoelectronically converts the received light into charge and transfers the
charge to each shift register. These shift registers then transfer the charge to the direction of the arrows
in the figure at the timing of transfer clocking. This transfer clock pulse is equally input into every chip,
and thus all the shift registers are driven at the same timing. The charge transferred into each chip is
then combined into each channel, and then output in a time division system. Furthermore the 4 chan-
nels simultaneously perform this process to output the scanning signals of these 4 systems in parallel.
1 2 3 642 643 644 645 646 647
Chip 1
Chip 1 Chip 2
Channel 1
e-STUDIO167/207/237
SCANNER
Chip 2
OS1
Chip 3 Chip 4 Chip 5
Channel 2
Primely scanning: 7084 pixels (1 line)
1286 1287 1288 1289 1290 1291
OS2
Chip 6 Chip 7 Chip 8
Channel 3
Fig. 6-6
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6 - 10
Analog output ( OS1 )
Transfer clock
Shift register
Light-receiving
sensor
1930 1931 1932
Chip 3
OS3
Chip 9 Chip 10 Chip 11
Channel 4
OS4