Read Sharp AR-M550 (serv.man4) Service Manual online
AR-M550/M620/M700 DETAILS OF EACH SECTION 6 - 60
3. Laser scan unit (LSU)
A. General
This section performs the following operations.
Image data sent from the MFP (image process circuit) through the
mother board and PCU are converted into laser beams to radiate onto
the drum surface.
mother board and PCU are converted into laser beams to radiate onto
the drum surface.
B. Major parts and signal functions
Code
Signal
name
Name
Type
Function/Operation
MODEL
NOTE
PGM
PGM
Polygon mirror (motor)
Reflects laser beams at the constant rotation speed.
BD
BD PWB
Detects the laser scan start timing. This device is
used to detect a laser trouble.
used to detect a laser trouble.
No.
Name
Function
1
Laser control PWB
Controls laser beam flashing and the output value.
2
Cylindrical lens
Converges laser beams to focus.
3
Incidence reflection mirror
Assures the optical path for laser beams.
4
No. 1 mirror
Assures the optical path for laser beams.
5
f
θ
lens 1
Deflects laser beams so that the laser scan speeds on the both ends of the drum and that at the center
of the drum are the same.
of the drum are the same.
6
f
θ
lens 2
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
9
8
7
6
5
4
3
2
1
9
8
7
6
5
4
3
2
1
12
11
10
12
11
10
9
8
7
6
5
4
3
2
1
9
8
7
6
5
4
3
2
1
12
11
10
12
11
10
13
14
15
16
17
18
14
15
16
17
18
13
14
15
16
17
18
14
15
16
17
18
4
3
2
1
6
5
4
3
2
1
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
BD
PGM
GND2
GND2
+5VLD
GND2
/PMCLK
/READY
/START
+24V1
+24V1
+24V1
GND2
GND2
VRB
GND2
GND2
GND2
GND2
GND2
GND2
GND2
/LDON
LSU S/H
/SYNC
+5V2
+5V2
CN-22
B30B-PHDSS-B
VIDEO
/VIDEO
GND2
GND2
GND2
GND2
GND2
/LDON
LSU S/H
/SYNC
/VIDEO
VIDEO
GND2
VIDEO
GND2
SMP-18V-NC/SMR-18V-N
GND2
GND2
+5VLD
GND2
/PMCLK
/READY
/START
+24V1
+24V1
+24V1
GND2
GND2
VRB
GND2
GND2
+5V2
+5V2
LD PWB
GND2
/SYNC
GND2
/SYNC
GND2
/PMCLK
/START
GND2
+24V1
GND2
+24V1
/READY
B6B-PH-K-S
B30B-PHDSS-B
GND2
GND2
+5VLD
GND2
/PMCLK
/READY
/START
+24V1
+24V1
+24V1
GND2
GND2
VRB
GND2
GND2
GND2
GND2
GND2
GND2
GND2
GND2
/LDON
/VIDEO
VIDEO
LSU S/H
/SYNC
+5V2
+5V2
+5V2
LSU UNIT
SMP-12V-NC/SMR-12V-N
TEST
TEST
TEST
(NC)
(NC)
TEST2
TEST3
TEST2
TEST3
TEST3
TEST2
/BRAKE
/BRAKE
CN-2
B4B-PH-K-S
PCU PWB
CN-1
CN-3
CN-6
CN-6
CN-8
CN-8
MOTHER
PWB
PWB
MFP
CONTROL
PWB
CONTROL
PWB
1
2
3
4
5
6
8
9
10
7
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