Service manual

Chapter 2
2-7
2.2.3 Controlling the Laser Scanner Motor
2.2.3.1 Outline
0008-2075
The control is utilized to rotate the scanner motor in order to strike laser beams to a proper position on the photosensitive drum.
The circuit diagram of the scanner motor control is illustrated below.
F-2-11
2.2.3.2 Scanner Motor Speed Control
0008-2009
This control is utilized to rotate the scanner motor at a constant speed by the DCNT Board controlling the scanner motor drive IC.
The scanner motor, which is integral with the scanner motor drive circuit, is a 3-phase, 12- pole DC brushless motor with a built-in Hall device.
The operations of the scanner motor control are described in the following.
After receiving a print command, the CPU in the DCNT Board sets the SCANNER MOTOR ACCELERATION (/ACC) signal "L" through the ASIC and then the
scanner motor starts to rotate.
The /BDI signal is sent from the BD circuit as the CPU emits light from the laser forcefully during scanner motor rotation. The ASIC compares a period of the /
BDI signal with the reference clock in the frequency comparator. Then it controls the scanner motor revs by controlling the /ACC signal and /DEC signal until the
revs reach a specified value.
2.2.3.3 Scanner Motor Failure Detection
0008-1549
The DCNT Board determines whether the scanner motor rotates at specified revs by monitoring the /BDI signal sent from the BD circuit.
The DCNT Board determines a optical unit failure or BD error, stops the printer engine, and notifies the failure to the SCNT Board, under the following conditions:
1) Optical unit failure
If the detected period of the /BDI signal does not satisfy a specified range within 20 seconds at scanner motor start-up, or if the /BDI signal cannot be detected for
0.5 second after the detected period of the signal has satisfied a specified range, the DC controller determines a optical unit failure.
2) BD error
If the input period of the /BDI signal is not within the range of +/-1.7% of the scanner motors specified revs during a print operation after the motor has reached
its specified revs, the DC controller determines a BD error.
2.3 Image Formation
2.3.1 Overview/Configuration
2.3.1.1 Outline
0007-4976
The image formation system, which serves as the nerve center of the printer, forms a toner image on paper.
It consists of a developing cylinder, four toner cartridges containing toner, a drum cartridge containing the ITB, photosensitive drum, etc., a developing rotary stor-
ing the toner cartridges, and a fixing unit, etc. These parts are controlled by the DCNT board.
After receiving a print command from the interface controller, the DCNT board the developing rotary, laser/scanner unit, high-voltage power supply circuit to form
an image based on the VIDEO signals on paper.
The toner cartridges and drum cartridge come with built-in memory tags that store cartridge usage condition information, etc. The DCNT board performs reading
and writing.
IC101
CPU
M
IC102
ASIC
+24VB
-1
J21-4
-3
-2
BD circuit
Integrator
circuit
Drive
circuit
Laser/scanner unit
Scanner driver IC
Scanner motor
129
130
/ACC
/ACC
/DEC
/DEC
Standard
clock
24
25
X101
Frequency
divider
Frequency
comparator
/BDI
DCNT Board
-4
J103-1
-2
-3
J31-2J116-2
+24VB