Panasonic KX-MB3030RU / KX-FAP106A7 Service Manual ▷ View online
37
KX-MB3030RU
6.7.2.
Scanner Motor Drive Circuit
6.7.2.1.
General
Scanner motor drive circuit is consist of motor driver, motor current control circuit , over current protection circuit and Relay drive
circuit.
One motor driver IC controls both FB (Flat Bed) and ADF (Auto Document Feeder) motors.
Output of motor driver is alternatively selected by the relay circuit.
(1) FB Motor
circuit.
One motor driver IC controls both FB (Flat Bed) and ADF (Auto Document Feeder) motors.
Output of motor driver is alternatively selected by the relay circuit.
(1) FB Motor
This motor functions for main operations including FAX transmission, FB copy and PC scan.
This motor feeds CIS unit with synchronizing for scanning.
A 1-step rotation of this motor feeds 0.021mm of CIS unit.
This motor feeds CIS unit with synchronizing for scanning.
A 1-step rotation of this motor feeds 0.021mm of CIS unit.
(2) ADF Motor
This motor functions for main operations including FAX transmission, ADF copy and PC scan.
This motor feeds document which are set to ADF with synchronizing for scanning.
A 1-step rotation of this motor feeds 0.042mm of document.
This motor feeds document which are set to ADF with synchronizing for scanning.
A 1-step rotation of this motor feeds 0.042mm of document.
6.7.2.2.
Block Diagram of Scanner motor Drive circuit
6.7.2.3.
Explanation of each circuit
6.7.2.3.1.
Motor driver
IC700 is the motor driver AN44067A.
This IC can drive up to 2.6A/phase and support up to 2W1-2 phase excitation.
When "enable" signal (IC700_pin19) becomes "L", motor driver is activated, and motor current are supplied from IC700_pin6,
pin8, pin10 and pin12 to drive the motor coil.
This IC can drive up to 2.6A/phase and support up to 2W1-2 phase excitation.
When "enable" signal (IC700_pin19) becomes "L", motor driver is activated, and motor current are supplied from IC700_pin6,
pin8, pin10 and pin12 to drive the motor coil.
Type of excitation is selected by the logic level of "ST1"(IC700_pin31), "ST2"(pin30) and "ST3"(pin29).
The operation of IC700 is shown in below table corresponding to each logic level of enable, ST1, ST2 and ST3.
The operation of IC700 is shown in below table corresponding to each logic level of enable, ST1, ST2 and ST3.
Table1:Motor driver operation mode
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KX-MB3030RU
IC700_pin32 determines the direction of motor rotation.
For the direction of motor rotation, refer to the below table.
For the direction of motor rotation, refer to the below table.
Table2:Motor rotation direction
After setting the above signals, clock signal is supplied from IC300_pinAM31 to PHA(IC700_pin28).
Whenever clock signal is supplied, IC700 output current value and direction are changed according to the above signal levels.
The frequency of clock signal also determines the motor speed.
"TJMON" signal is supplied from IC700_pin3 which informs IC300 the stability point of motor excitation.
When this signal "L", IC300 recognizes that current status is motor stability point.
Whenever clock signal is supplied, IC700 output current value and direction are changed according to the above signal levels.
The frequency of clock signal also determines the motor speed.
"TJMON" signal is supplied from IC700_pin3 which informs IC300 the stability point of motor excitation.
When this signal "L", IC300 recognizes that current status is motor stability point.
6.7.2.3.2.
Motor current control circuit
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.
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, Vref voltage of IC700 is controlled.
When Vref voltage is high, motor current is increased, and the voltage is low, motor current is reduced.
When Vref voltage is high, motor current is increased, and the voltage is low, motor current is reduced.
For the control of Vref voltage, PWM pulse is supplied from IC300_pinAP33 .
PWM pulse is inverted by FET Q712 and integrated by R783, R782, and C764.
Consequently PWM pulse is converted to DC voltage.
When duty of PWM pulse is high, Vref voltage is decreased and when duty is low, Vref voltage is increased.
PWM pulse is inverted by FET Q712 and integrated by R783, R782, and C764.
Consequently PWM pulse is converted to DC voltage.
When duty of PWM pulse is high, Vref voltage is decreased and when duty is low, Vref voltage is increased.
"CRMEN(IC300_pinAL33)" is the select signal of FB and ADF.
In ADF mode, this signal is "L" and FET Q713 turns OFF. Then the max voltage of Vref become 3.3V.
In FB mode, since FB motor need less current than ADF motor, this signal is "H" and FET Q713 turns On.
Then the max Vref voltage is divided by R783 and R785, makes max Vref voltage approx 1.1V
In ADF mode, this signal is "L" and FET Q713 turns OFF. Then the max voltage of Vref become 3.3V.
In FB mode, since FB motor need less current than ADF motor, this signal is "H" and FET Q713 turns On.
Then the max Vref voltage is divided by R783 and R785, makes max Vref voltage approx 1.1V
6.7.2.4.
Circuit diagram of motor current control and Over current protection circuit
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KX-MB3030RU
6.7.2.5.
Timing chart of current control
Following timing charts are the example of Vref voltage corresponding to PWM pulse duty.
6.7.2.6.
Over Current protection circuit
6.7.2.6.1.
Function
By parts failure or other reason, if Vref voltage exceeds 1.2V, extreme current is supplied to the FB motor. This may cause FB
motor over heat and damage.
To prevent this problem, over current protection circuit is provided.
In FB mode, if Vref voltage becomes over 1.2V, Q718 turns on. Then STBY (IC700_pin22) becomes "L" and IC700 stops output
the motor current.
Q719 is provided to operate this protection circuit only in FB mode.
motor over heat and damage.
To prevent this problem, over current protection circuit is provided.
In FB mode, if Vref voltage becomes over 1.2V, Q718 turns on. Then STBY (IC700_pin22) becomes "L" and IC700 stops output
the motor current.
Q719 is provided to operate this protection circuit only in FB mode.
6.7.2.6.2.
Circuit diagram
Refer to the circuit diagram (Circuit diagram of motor current control and Over current protection circuit (P.38).)
6.7.2.7.
Relay Drive circuit
6.7.2.7.1.
Function
A relay is used to select which motors should be supplied the motor control current from IC700.
When relay is off, FB motor is selected, and when relay is on, ADF motor is selected.
In case of IC300_pinAL33 is "H", since both Q717 and Q715 are turned off, the relay RL700 is not activated (FB motor is
selected).
On the other hand, IC300_pinAL33 is "L", since both Q717 and Q715 are turned on, the relay RL700 is activated (ADF motor is
selected).
When relay is off, FB motor is selected, and when relay is on, ADF motor is selected.
In case of IC300_pinAL33 is "H", since both Q717 and Q715 are turned off, the relay RL700 is not activated (FB motor is
selected).
On the other hand, IC300_pinAL33 is "L", since both Q717 and Q715 are turned on, the relay RL700 is activated (ADF motor is
selected).
6.7.2.7.2.
Circuit diagram
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KX-MB3030RU
6.7.2.8.
Timing chart and wave form of scanner motors
Control sequence and waveform of both FB and ADF motor are almost same.
6.7.2.8.1.
Normal 1-2 phase excitation (half step)
ST1="L",ST2="H",ST3="L"
(1) Timing chart
(2) Wave form
6.7.2.8.2.
Flat torque 1-2 phase excitation (half step)
ST1="H",ST2="L",ST3="L"
(1) Timing chart
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