Then the scanner driver IC rotates the scanner motor when the /ACC signal puts into "L". The scanner motor increases the rotational count only during the /ACC

signal is "L".

The CPU allows the laser to emit light with APC during the scanner motor is rotating. Accordingly, the BD INPUT signal (/BDI) is sent to the CPU from the BD

sensor via the video controller. The CPU compares the intervals between the /BDI signal and the reference clock with the frequency comparator in the CPU, and

controls the rotational count of the scanner motor by controlling the /ACC signal until the rotational count reaches its prescribed count.

The CPU decreases the rotational count of the scanner motor by putting the SCANNER MOTOR DECRELATION signal (/DEC) into "L" and the ACCELERA-

TION signal (/ACC) into "H" to stop the scanner motor.

2.3.4.3 Scanner motor failure detection

LBP3370 / LBP3310

The CPU monitors the /BDI signal from the BD sensor via the video controller, and determines if the scanner motor rotates at its prescribed rotational count or not.

The CPU determines the failure or the error and notifies it to the video controller under the following conditions.

1) Scanner failure

When the /BDI signal is not detected within 0.9 sec. after the forced acceleration of the scanner motor is completed, it is detected for another 60 sec, and if the

interval of the /BDI signal cannot be detected at specified amount during this period.

2) BD failure

If the /BDI signal is not detected within 100msec. after the forced acceleration of the scanner motor. Or if the interval of the /BDI signal is not detected at a

specified value for longer than 2 sec. continuously, after the scanner motor reaches its prescribed rotational count.

3) BD error

If the /BDI signal is not detected in the prescribed interval during the CPU is outputting the /BD signal to the video controller.

Exceptional cases:

If the door open is detected within 200 msec. after the BD error is detected, the CPU does not notify the BD error to the video controller.

Also if the scanner failure or the BD failure is detected after the BD error is detected, the CPU releases the BD error.

2.4 IMAGE FORMATION SYSTEM

2.4.1 Overview/Configuration

2.4.1.1 Outline

LBP3370 / LBP3310

The image formation system serves as the nerve center of the printer. It consists of the cartridge, the transfer charging roller, and the fixing unit etc.

Video controller PCB

J201

/BDI

-17

+24VA

-27

/ACC

-21

/DEC

-22

-16

X201