OKIDATA OL1200ex, Service Manual

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%2.4 Electro-Photographic Process
2.4 Electro-photographic Process
2.4.1 Electro-photographic process mechanism
This mechanism prints image data from the control board on the paper by electro-photographic process.
The Figure 2-4 shows the layout of the electro-photographic process mechanism.
(1) Image drum unit
The image drum unit consists of a sensitive drum, a charger, and a developer. The unit forms a
toner image on the sensitive drum, using a electrostatic latent image formed by the LED head.
(2) Hopping motor
This motor is a pulse motor of 48 steps/rotation that is two-phase excited by the signal from the
control board. It drives the hopping roller of the first tray and the front feed roller via two one-way
clutches according to the direction of rotation.
(3) Registration motor
This motor is a pulse motor of 48 steps/rotation that is two-phase excited by the signal from the
control board. It drives the registration roller.
(4) Drum motor
This drum motor is a pulse motor of 48 steps/rotation that is two-phase excited by the signal from
the control board and is the main motor of this mechanism.
(5) LED head
Image data for each dot line from the control board is received by the shift register and latch
register. The 5120 LEDs are driven to radiate the image data to the image drum.
(6) Fuser
The fuser consists of a heater, a heat roller, a thermistor and a thermostat. An AC voltage from the
power supply board is applied to the heater under the control of the HEATON signal from the
control board. This AC voltage heats the heater. The control board supervises the heat roller
temperature via the thermistor, and regulates the heater roller at a predetermined temperature
(185 ~ 188°C) by connecting or disconnecting the AC voltage supply to the heater. If the heater
roller temperature rises abnormally, the thermostat of the heater voltage supply circuit is activated
to cut the AC voltage supply forcibly.