M11 (Scanner) Control - Minolta Di551 Service Manual

SCANNER SECTION

[3] M11 (Scanner) Control

SCAN CLK
SCAN FR
SCAN MGN
SCAN CUR1
SCAN CUR2
SCAN CUR3
MODE1
MODE2
MODE3
SCANHP PS
PRCB
5V2
S.GND
24V1
5V2
S.GND
P.GND
DCPS
M11 (scanner) is driven by SCDB (scanner drive
board) and is controlled by PRCB (printer control
board).
The related signal is PS61 (scanner HP).
1. Operation
a. Operation of M11 (scanner)
M11 (scanner) is a 3-phase stepping motor
driven by the 3-phase bipolar constant-current
drive method. The motor is turned ON/OFF by
supplying/stopping clock pulses.
The rotational speed, direction, and amount of
movement of M11 is determined by the incre-
ment of the driving step count. This count is reset
each time PS61 (scanner HP) is turned ON or
OFF by the exposure unit.
b. Movement speed of the exposure unit
Scanning speed
Operation mode
Scan
Return
Home position search 247 mm/s
U
M11
V
W
S.GND
PS61
SIG
5V
SCDB
Movement speed
320 mm/s (1:1)
640 mm/s
2-C-2
c. Exposure unit home position search
When SW2 (sub power switch) or the START
button is pressed, M11 (scanner) searches for
the home position of the exposure unit. However,
this operation is performed in different ways
depending on whether PS61 (scanner HP) is ON
or OFF.
(1) When PS61 (scanner HP) is OFF
PS61
Platen APS read position
(2) When PS61 (scanner HP) is ON
PS61
d. Read with shading correction
Shading correction is performed in different ways
depending on whether SW2 (sub power) is ON or
the START button is ON. When shading correc-
tion starts, the exposure unit is at the home posi-
tion and PS61 (scanner HP) is OFF.
(1) When SW2 (sub power) is ON
L1 (exposure lamp) turns ON. Next, M11 (scan-
ner) moves the exposure unit toward the paper
exit side. After being driven by the specified num-
ber of steps, M11 stops, thus reading the light
reflected by the white reference plate installed
underneath the glass stopper plate and perform-
ing the first white correction. Next, M11 moves
the exposure unit toward the paper exit side.
After being driven by the specified number of
steps, M11 performs the second white correc-
tion.
Then, L1 is turned OFF for black correction,
searching for the home position of the exposure
unit.
In each of the first and second shading correction
processes, the CCD 1 line data is read to com-
pare brightness levels between pixels. The
brighter data is used as white correction data.
Platen APS read position