Engine Controller System; Flash Memory; Print Density Control; High-Voltage Generator - Kyocera Mita FS-6750 Service Manual

Operation theory

Engine controller system

4.5 Engine controller system
The engine controller provides control over all print engine activities. It drives
laser, coordinates the electrophotography process with print data from the main
logic con-troller. The engine system also manages information collected back from
sensors, etc., so that a message is given in case of need for user attention.
The engine controller is responsible for the following systems, explained step by
step in the following sections.

Flash memory

The engine controller uses a flash memory to store environmental parameters that
does not require a battery backup. The flash memory is driven by +5 V power and
de-signed to stand reading and writing for nominally 100,000 times.

Print density control

The print density is adjusted by means of changing the clock frequency of the
developer bias system. The density is higher when the clock frequency is low; the
density is lower when the clock frequency is high.

High-voltage generator

The main clock of HVCLK1 is program-divided to generate the oscillator output.
This is up-verted using a transformer in the high-voltage circuit. The divisor fre-
quency is determined by the 8-bit register. The oscillation is toggled by the engine
CPU.

Laser scanner control

In order to activate the laser scanner, the engine controller does the following
tasks:
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Polygon motor control

The output frequency signal to the polygon motor is generated by the engine gate
ar-ray as it divides the engine system clock. The polygon motor is of 26645.7 rpm
and the frequency is 2664.57 Hz.
The engine CPU attempts to detect the horizontal synchronization signal so that
the laser diode is normally triggered. If the horizontal synchronization output is
not found after the laser driving current control (LASER*) is set low, the engine
CPV recognizes it as the failure on the APC board and gives the 4200 error.
FS-6750
Forced laser activation timing
Laser diode current limit
Laser power control output
Beam detection photo-sensor output
Polygon motor activation
Polygon motor readiness detection
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