Sharp MX-6500N / MX-7500N (serv.man27) Service Manual ▷ View online
MX-7500N OPERATIONAL DESCRIPTIONS 13 – 37
4
Primary transfer idle roller
Transfer belt follower.
5
Primary transfer belt drive roller
Drives the transfer belt.
6
Primary transfer belt follower roller
Transfer belt follower.
7
Primary transfer belt tension roller
Apply a tension to the transfer belt.
8
Belt CL brush
Transfer belt back surface cleaning.
9
PTC opposing roller
Roller to flow a PTC current.
10
Secondary transfer belt
Transfers toner images on the primary transfer belt to paper.
11
Secondary transfer roller
Transfers toner images on the primary transfer belt to paper.
12
Secondary transfer belt drive roller
Drives the transfer belt.
13
Secondary transfer belt follower roller
Transfer belt follower.
14
PTC unit
Reduces the positive charges on the primary transfer belt.
15
Registration backup roller
Holds the belt position in the registration section in the process control.
16
Secondary transfer blade
Cleans remaining toner on the secondary transfer belt.
No.
Name
Function/Operation
MX-7500N OPERATIONAL DESCRIPTIONS 13 – 38
(3)
Process registration sensor section
Signal name
Name
Function/Operation
PCSS
Color image density sensor PWB reflection plate shutter solenoid
Opens/closes the shutter of the process control and the registration
sensor.
sensor.
PTCCHPD
PTC cleaner home position detection
Detects the PTC cleaner home position.
REGS_C/PCS_C
Color image density sensor/Image registration sensor C
Detection of registration shift on the machine front (C) side, and
detection of the M/BK toner patch density.
detection of the M/BK toner patch density.
REGS_F/PCS_F
Color image density sensor/Image registration sensor F
Detection of registration shift on the machine front (F) side, and detection
of the C toner patch density.
of the C toner patch density.
REGS_R/PCS_R
Color image density sensor/Image registration sensor R
Detection of registration shift on the machine front (R) side, and
detection of the Y toner patch density.
detection of the Y toner patch density.
PTCCHPD
REGS_R /PCS R
REGS_C /PCS_C
REGS_F /PCS_F
PCSS
SMP-02V-NC
SMR-02V-N
2
1
2
1
1
24V3
PCSS
PCSS
179228-2
6-292254-2
02XR-6H-P
1
2
2
2
1
PCSS
24V3
21CSR-8PK
(NC)
PCU PWB
GND
5VN
GND
5VN
PCSS
REGS_R_LED
REGS_R
PCS_R
PCS_R
REGS_C_LED
GND
5VN
REGS_C
PCS_C
PCS_C
REGS_F_LED
REGS_F
PCS_F
PCS_F
15
13
14
12
11
10
11
10
9
8
7
6
5
4
3
2
1
8
7
6
5
4
3
2
1
17
16
16
18
19
20
21
GND
5
VNPD+R
PTCCHPD
(NC)
(NC)
21CSR-8PK
B21B-CSRK
24V3
CN-16
BU21P-TCS-LE
1
12
11
10
9
8
7
2
3
4
5
6
3
4
5
6
13
14
15
16
17
18
19
20
21
14
15
16
17
18
19
20
21
(NC)
PCSS
GND
5VN
REGS_R_LED
REGS_R
PCS_R
PCS_R
GND
5VN
REGS_C_LED
REGS_C
PCS_C
PCS_C
GND
5VN
REGS_F_LED
REGS_F
PCS_F
PCS_F
GND
PTCCHPD
5VNPD+R
24V3
(NC)
12
1
2
5
6
8
9
11
10
10
4
3
3
7
15
14
13
14
13
16
17
18
19
20
21
21CSR-8PK
1
2
2
4
5
5
3
1
2
2
4
5
5
3
D-GND
REGS_C
PCS_C
PCS_C
5VN
REGS_R_LED#
D-GND
REGS_R
PCS_R
PCS_R
5VN
REGS_C_LED#
05XR-6H-P
05XR-6H-P
1
2
2
4
5
5
3
5VNPD
D-GND
D-GND
REGS_F
PCS_F
PCS_F
1
2
3
2
3
GND
PTCCHPD
5VNPD+R
REGS_F_LED#
03XR-6H-P
05XR-6H-P
MX-7500N OPERATIONAL DESCRIPTIONS 13 – 39
B. Operational descriptions
(1)
Transfer
a. Transfer operation
a-1. Transfer operation
Toner images on the OPC drum are transferred to the primary
transfer belt by applying the positive high voltage to the primary
transfer roller.
transfer belt by applying the positive high voltage to the primary
transfer roller.
Negative charge is generated by the PTC unit, and this strengthens
negative charges on the transfer belt, improving the secondary
transfer efficiency.
negative charges on the transfer belt, improving the secondary
transfer efficiency.
By this operation, the transfer efficiency in the secondary transfer is
improved.
improved.
Then a high negative voltage is applied to the primary transfer belt
to transfer the toner images from the primary transfer belt to paper.
to transfer the toner images from the primary transfer belt to paper.
In the monochrome mode and the color mode, the black (K) trans-
fer voltage is selected.
fer voltage is selected.
a-2. Cleaning operation
Toner is cleaned by the secondary transfer cleaning blade, and
transported to the waste toner section.
transported to the waste toner section.
Unnecessary toner remained on the secondary transfer belt is
transferred to the primary transfer belt by making the polarity of the
applying voltage to the primary transfer belt. Then it is cleaned by
the primary transfer belt cleaning blade to be transported to the
waste toner section.
transferred to the primary transfer belt by making the polarity of the
applying voltage to the primary transfer belt. Then it is cleaned by
the primary transfer belt cleaning blade to be transported to the
waste toner section.
b. Primary (intermediate) transfer roller separation
mechanism and contents
The primary transfer roller operates pressing all the rollers, sepa-
rates all the rollers, or presses only black depending on the opera-
tion mode.
rates all the rollers, or presses only black depending on the opera-
tion mode.
When the roller separation clutch (1TURC) turns ON, the transfer
cam rotates to shift the primary transfer link and the primary trans-
fer arm linked with the cam in the arrow direction, performing sepa-
rating operation of the roller.
cam rotates to shift the primary transfer link and the primary trans-
fer arm linked with the cam in the arrow direction, performing sepa-
rating operation of the roller.
It also performs all pressing, all separating, or pressing only black
with the roller separation sensors (1TUD_CL, 1TUD_K) and the
separation detection arm.
with the roller separation sensors (1TUD_CL, 1TUD_K) and the
separation detection arm.
PTC
1TUD_CL
1TUD_BK
All pressing
ON
OFF
All separating
OFF
ON
Pressing only black
OFF
OFF
All separating
Pressing only black
All pressing
MX-7500N OPERATIONAL DESCRIPTIONS 13 – 40
c. Secondary transfer belt skew adjustment
c-1. Belt skew detection.
Secondary transfer belt skew is detected by the sensor (a. 2nd
transfer belt skew detection sensor R) or (b. 2nd transfer belt skew
detection sensor F).
transfer belt skew detection sensor R) or (b. 2nd transfer belt skew
detection sensor F).
When the belt skews (A) direction, (a) sensor detects it.
c-2. Belt skew correction.
When the 2nd transfer belt skew is detected, (a) 2nd transfer belt
skew correction motor operates (b) skew correction arm to twist the
2nd transfer belt.
skew correction motor operates (b) skew correction arm to twist the
2nd transfer belt.
(2)
Image density detection and registration detection
The image density and the image registration are detected by the
sensors provided at the front, the center, and the rear of the frame.
sensors provided at the front, the center, and the rear of the frame.
a. Function and operation of the color image density sensor/
image registration sensor
a-1. Image registration sensor
The shift of the image registration (F, C, R) is detected.
a-2. Process control sensor/Image registration sensor
Sensitivity adjustment of the color sensor light receiving ele-
ments (Photo transistors)
ments (Photo transistors)
Purpose: To maintain the sensitivity of the light receiving elements
even if the environmental conditions (temperature and humidity)
vary.
even if the environmental conditions (temperature and humidity)
vary.
Execution timing: This adjustment is executed in the process con-
trol when the temperature or the humidity varies.
trol when the temperature or the humidity varies.
Method: Use the patch written on the primary transfer to adjust the
sensor sensitivity.
sensor sensitivity.
Light emitting current of the sensor LED (Light emitting diode)
Purpose: To maintain the light emitting quantity of the sensor even
if the sensor LED is aged or the environmental conditions vary.
if the sensor LED is aged or the environmental conditions vary.
Execution timing: Every time when the process control is made.
Method: Reflection on the surface of the primary transfer belt is
used to adjust the sensor sensitivity.
used to adjust the sensor sensitivity.
AA
B
$
%
$
%
$
%
AA
AB
$
%
Process control sensor
Image registration sensor
Rear
Y
R
Center
M/BK
C
Front
C
F
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