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<Stop operation>
In order to stop the motor rotation, following 2 signals are supplied from IC300.
1. SS signal (Output pin: Pin AN29/Output Signal: "L")
When this signal is inverted by transistor Q502 and becomes "H", motor recognize this signal as "stop" signal.
2. Brake signal (Output pin: Pin AL29/Output Signal: "L")
When this signal is inverted by transistor Q526 and becomes "H", motor recognize this signal as "brake on" signal.

Timing Chart of Stop operation

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General

Scanner motor drive circuit is consist of motor current control circuit ,FB (Flat Bed) motor driver and ADF (Auto Document Feeder)
motor driver .

1. Circuit explanation

According to the scan speed, each motor current is controlled for appropriate value.
When scan speed is low, motor current is reduced to prevent the vibration during motor rotation. 
When scan speed is high, motor needs much driving force. so much current should be supplied.

For the control of motor current, Vref voltage of each motor driver is controlled.
When Vref voltage is high, motor current is increased, and the voltage is low, motor current is reduced.
In order to control of Vref voltage, PWM pulse is supplied from IC300 pin AP33 .
PWM pulse is inverted by Q521 and integrated by R533, R534, and C567, then convert to DC voltage.

This DC voltage is supplied to Vref pin of each motor driver through Q522.
When duty of PWM pulse is high, Vref voltage is decreased and when duty is low, Vref voltage is increased.

For FB motor, motor current is controlled approx. 0.1A-0.25A.
For ADF motor, motor current is controlled approx. 0.2A-0.35A.

2. Circuit diagram

3. Timing chart

Following timing charts are the example when PWM pulse duty are approx 9% and 45%.

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1. Functions

This motor functions for main operations including FAX transmission, FB copy and PC scan.
This motor feeds CIS unit with synchronizing for reading.

2. Motor operation

During motor driving, pin AL33 of IC 300 become low level, then motor driver IC502 is activated.
Stepping pulses are output from IC300 pins AN34, AM33, AM34, AM31, AP32 and AN32 causing driver IC502 pin 3, 7, 9 and
13 to drive the motor coil.
A 1-step rotation of this motor feeds 0.021mm of CIS unit.

3. Circuit Diagram

1. Functions

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 reading.

2. Motor operation

During motor driving, pin AL32 of IC300 become low level, then motor driver IC700 is activated.
Stepping pulses are output from IC300 pins AN34, AM33, AM34, AM31, AP32 and AN32 causing driver IC700 pin 3, 7, 9 and
13 to drive the motor coil.
A 1-step rotation of this motor feeds 0.042mm of document.

3. Circuit Diagram

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Control sequence and waveform of both FB and ADF motor are almost same.

1. Timing chart

2. Wave form