Document Scanning Sequence - Canon CANOSCAN N1220U Service Manual

CHAPTER 2
B. Document Scanning Sequence
SEQUENCE
Times required (s)
Drive motor (M1)
LED ON signal
Interface signal
(Data 1-8)
Scanning unit position
Home position
Border between
black and white
Document scan area
Sequence
After a power on sequence
STBY
is completed until the
(Standby)
scanner receives a scan
command from the host
computer.
After the scanner received a
HPDET
scan command until the
(Home position
home position is detected.
detection)
After the home position is
STUP
detected until document
(Setup)
scan starts.
After the scanning unit
SCFW
starts moving forward
(Scanning unit
until it reaches the
forward)
starting position of the
scan area specified by the
host computer.
SCAN
After the scanning unit
(Document
starts scanning until all
scan)
area specified by the host
computer are scanned.
SCRTN
After the scanning unit
(Scanning unit
starts moving backward
return)
until it returns to the
home position.
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COPYRIGHT 2000 CANON INC.
STBY HPDET STUP
Scan command is received
8 sec.
Figure 2-9
To maintain the scanner
ready for scan.
To detect the home position
and a border between black
and white.
To make a gate array setting,
buffer RAM initialization, etc.
as a preparation for scan.
To move the scanning unit
with a uniform speed to the
vertical scanning position
specified by the host
computer.
To perform various image
processing according to the
command from the host
computer and transmit the
image data during scan.
To return the scanning unit
to the home position to
ready for the next scan.
Table 2-1
CANOSCAN N650U/N656U/N1220U REV.0 JUNE 2000 PRINTED IN JAPAN (IMPRIME AU JAPON)
SCFW SCAN
Purpose
If the border detection between
black and white is failed, the
scanning unit stops there and
proceeds to the next step.
The home position is detected
by the home position sensor.
SCRTN STBY
(A4, 1200dpi, 100%, 24bit color)
: Reverse
Remarks