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KX-MB2230RU/ KX-MB2270RU/ KX-MB2510RU/ KX-MB2540RU

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.

2. Block Diagram of Scanner motor Drive circuit

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KX-MB2230RU/ KX-MB2270RU/ KX-MB2510RU/ KX-MB2540RU

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.

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).

The relation between motor excitation mode and logic level of "ENABLEAB"/"ENABLECD", "ST1AB"/"ST1CD", "ST2AB"/
"ST2CD" and "ST3AB"/"ST3CD" are shown in below table.

Table1: Motor driver Excitation mode                                               *(pinxx) represents the pin No. of IC502

"DIRAB"(IC502_pin38) and "DIRCD"(IC502_pin47) determine the direction of motor rotation.
Although "DIRCD" determines the Main motor rotation direction, direction is  not changed.
So "DIRCD" is fixed "H" level.
The relation between these signals and motor rotation directions are shown in below table.

Table2: Motor rotation direction                                                  *(pinxx) represents the pin No. of IC502

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 exci-
tation mode which is determined by above signal levels.
The clock frequency also determines the motor speed.

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. 

2. Circuit Diagram

Please refer to the circuit diagram shown in the block diagram of Scanner motor drive circuit (P.41).

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.

ENABLEAB(pin40)

or

ENABLECD(pin45)

ST1AB(pin35)

or

ST1CD(pin50)

ST2AB(pin36)

or

ST2CD(pin49)

ST3AB(pin37)

or

ST3CD(pin48)

Excitation 

mode

L

-

-

-

Disable

H

L

L

L

2 Phase(Not 

used)

H

L

H

L

N1-2phase

H

H

L

L

F1-2phase

H

H

H

L

W1-2phase

H

L

L

H

2W1-2phase

Motor

DIRAB(pin38)

Operation Mode

FB

L

Scan

H

Return

Motor

DIRCD(pin47)

Operation Mode

ADF

L

FEED

H

Not used

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KX-MB2230RU/ KX-MB2270RU/ KX-MB2510RU/ KX-MB2540RU

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.

1. Function

If motor driver can supply more than 15 watts, FB motors may become fire hazards.
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 (=0.44Ax2.7ohm/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
(=0.44Ax24V).
By limiting the wattage less than 15W, risk of fire hazard is eliminated.

Also "CRM1"siglal 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.

(2)Example of Duty=65% 

H:20usec/div

(2)Example of Duty=93% 

H:20usec/div

f=Approx 30KHz

f=Approx 30KHz

Point A
(2V/Div)

    Point B
(0.5V/Div)

Point A
(2V/Div)

    Point B
(0.5V/Div)

Vref=0.76V

Vref=1.1V

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KX-MB2230RU/ KX-MB2270RU/ KX-MB2510RU/ KX-MB2540RU

1. 2 Phase excitaton

2. Normal Torque 1-2 Phase excitation

3. Flat Torque 1-2 Phase excitation

4. W1-2 Phase excitation

1. 2 Phase excitation

CLKCD

(Pin46_IC600)

DOUT2

(Pin5_IC600)

Fig.

Main Motor

current*

5V/Div

10V/Div

1A/Div

1