Panasonic KX-MB1500UCB / KX-MB1500UCW / KX-MB1520UCB / KX-MB1530UCB Service Manual ▷ View online
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KX-MB1500UC/KX-MB1520UC/KX-MB1530UC
6.7.3.
Scanner motor drive circuit (KX-MB1530 ONLY)
1. General
Scanner motor drive circuit consists of "Motor driver", "Motor current control circuit", and "O.C.P (Over Current Protection) cir-
cuit".
Scanner motor represents FB (Flatbed) motor and ADF (Auto document Feeder) motor.
FB motor feeds CIS unit in FB scan, FB copy, and FB FAX mode.
A one step rotation of this motor feeds CIS unit 0.021mm.
ADF motor feeds documents in ADF scan, ADF copy, and ADF FAX mode.
A one step rotation of this motor feeds documents 0.042mm.
cuit".
Scanner motor represents FB (Flatbed) motor and ADF (Auto document Feeder) motor.
FB motor feeds CIS unit in FB scan, FB copy, and FB FAX mode.
A one step rotation of this motor feeds CIS unit 0.021mm.
ADF motor feeds documents in ADF scan, ADF copy, and ADF FAX mode.
A one step rotation of this motor feeds documents 0.042mm.
2. Block Diagram of Scanner motor Drive circuit
6.7.3.1.
Motor driver
IC502 is the motor driver AN44071A.
This motor driver can drive both FB and ADF motors with 1 chip, and can supply up to 1.7A/phase and support up to 2W1-2
phase excitation.
When "CRMEN" signal (IC502_pin40) becomes "H", FB block of motor driver is activated, and motor currents are supplied from
IC502_pin24, pin28, pin29 and pin33 to drive the FB motor coils.
When "ADFMEN" signal (IC502_pin45) becomes "H", ADF block of motor driver is activated, and motor currents are supplied
from IC502_pin1, pin5, pin52 and pin56 to drive the ADF motor coils.
This motor driver can drive both FB and ADF motors with 1 chip, and can supply up to 1.7A/phase and support up to 2W1-2
phase excitation.
When "CRMEN" signal (IC502_pin40) becomes "H", FB block of motor driver is activated, and motor currents are supplied from
IC502_pin24, pin28, pin29 and pin33 to drive the FB motor coils.
When "ADFMEN" signal (IC502_pin45) becomes "H", ADF block of motor driver is activated, and motor currents are supplied
from IC502_pin1, pin5, pin52 and pin56 to drive the ADF motor coils.
FB motor excitation mode is selected by the logic level of "ST1AB", "ST2AB" and "ST3AB" (IC502_pin35-pin37).
ADF motor excitation mode is selected by the logic level of "ST1CD", "ST2CD" and "ST3CD" (IC502_pin50-pin48).
ADF motor excitation mode is selected by the logic level of "ST1CD", "ST2CD" and "ST3CD" (IC502_pin50-pin48).
The relation between motor excitation mode and logic level of "ENABLEAB"/"ENABLECD", "ST1AB"/"ST1CD", "ST2AB"/
"ST2CD"and "ST3AB"/"ST3CD" are shown in below table.
"ST2CD"and "ST3AB"/"ST3CD" are shown in below table.
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KX-MB1500UC/KX-MB1520UC/KX-MB1530UC
"DIRAB"(IC502_pin38) and "DIRCD"(IC502_pin47) determine the direction of motor rotation.
The relation between these signals and motor rotation directions are shown in below table.
The relation between these signals and motor rotation directions are shown in below table.
After setting the above signals, clock signal is supplied from IC300_pinA10 to "CLKAB"(IC502_pin39) and "CLKCD"
(IC502_pin46).
Whenever clock signal is supplied, current value and direction supplied to Scan motors change according to the excitation mode
which is determined by above signal levels.
The clock frequency also determines the motor speed.
(IC502_pin46).
Whenever clock signal is supplied, current value and direction supplied to Scan motors change according to the excitation mode
which is determined by above signal levels.
The clock frequency also determines the motor speed.
6.7.3.2.
Motor current control circuit
1. Function
According to the scan speed, motor current is controlled for appropriate value.
For example, when scan speed is low, motor has enough driving force.
So to prevent the vibration and noise during motor rotation, motor drive current should be reduced.
When scan speed is high, motor needs much driving force. so much current should be supplied.
In order to control the motor current, VREFAB and VREFCD voltages of IC502 is controlled.
When VREFAB and VREFCD voltages are high, motor currents are increased, and the voltages are low, motor currents are
reduced.
For example, when scan speed is low, motor has enough driving force.
So to prevent the vibration and noise during motor rotation, motor drive current should be reduced.
When scan speed is high, motor needs much driving force. so much current should be supplied.
In order to control the motor current, VREFAB and VREFCD voltages of IC502 is controlled.
When VREFAB and VREFCD voltages are high, motor currents are increased, and the voltages are low, motor currents are
reduced.
2. Circuit Diagram
Please refer to the circuit diagram shown in the block diagram of FB (Flat bed) motor drive circuit (KX-MB1500/1520 ONLY)
(P.39).
(P.39).
3. Circuit explanation
For the sake of VREFAB and VREFCD voltage control, PWM pulse is supplied from IC300_pinD8.
PWM pulse is integrated by R671, R672 and C657, then converted to DC voltage.
This DC voltage is supplied to VREFAB and VREFCD pins of IC502.
When duty of PWM pulse is high, VREFAB and VREFCD voltages are increased and when duty is low, VREFAB and
VREFCD voltages are decreased.
PWM pulse is integrated by R671, R672 and C657, then converted to DC voltage.
This DC voltage is supplied to VREFAB and VREFCD pins of IC502.
When duty of PWM pulse is high, VREFAB and VREFCD voltages are increased and when duty is low, VREFAB and
VREFCD voltages are decreased.
4. Timing chart of current control
Following timing charts are the example of VREFCD voltage corresponding to PWM pulse duty.
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KX-MB1500UC/KX-MB1520UC/KX-MB1530UC
6.7.3.3.
O.C.P (Over Current Protection) circuit
1. Function
If motor driver can supply more than 15 watts, FB and ADF motors may become fire hazards.
To prevent the risk of fire, this circuit is provided.
To prevent the risk of fire, this circuit is provided.
2. Circuit Diagram
3. Circuit explanation
When the current supplied from 24V exceeds 0.44A, the voltage between two registers R657 and R658 becomes more than
0.6V (=0.44A*2.7ohm/2), consequently both Q650 and Q651 turn on, then "STBY" signal (IC502_pin44) becomes "Low" level.
When "STBY" signal becomes "Low" level, IC502 is deactivated and currents of both motors are cut off.
So the currents which IC502 can supply are limited to less than 0.44A and the wattage is also limited to less than 10.7W
(=0.44A*24V).
By limiting the wattage less than 15W, risk of fire hazard is eliminated.
0.6V (=0.44A*2.7ohm/2), consequently both Q650 and Q651 turn on, then "STBY" signal (IC502_pin44) becomes "Low" level.
When "STBY" signal becomes "Low" level, IC502 is deactivated and currents of both motors are cut off.
So the currents which IC502 can supply are limited to less than 0.44A and the wattage is also limited to less than 10.7W
(=0.44A*24V).
By limiting the wattage less than 15W, risk of fire hazard is eliminated.
Also "CRM1" signal is provided from IC300_pinB10 to base of Q651.
This signal is designed to become "High" when software can not control motors properly by some accidents.
When base of Q651 becomes "High", "STBY" signal becomes "Low" and motor currents are cut off.
Therefore even in the case of software can not control motors, motors stop automatically for securing safety.
This signal is designed to become "High" when software can not control motors properly by some accidents.
When base of Q651 becomes "High", "STBY" signal becomes "Low" and motor currents are cut off.
Therefore even in the case of software can not control motors, motors stop automatically for securing safety.
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KX-MB1500UC/KX-MB1520UC/KX-MB1530UC
6.8.
Timing chart and wave form of scanner motors (KX-MB1500/1520 ONLY)
6.8.1.
Drive mode of FB motor
Correspondent table of operation
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