Panasonic Panafax UF-585, Service Manual

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6.1.4 Printing Process Operation
Charge
In the dark, the Bias Charge Roller (BCR) applies a high, uniform negative charge to the surface of the OPC Drum. The surface
potential is approximately -650 VDC and remains because the drum has a high electric resistance in the dark.
Exposure
A portion of the laser beam is deflected to the timing sensor [Beam Detection (BD) Sensor], which controls the start timing of
scanning on the OPC Drum. The CPU also uses the timing sensor to detect abnormal signals. The light beam from the laser
diode is modulated by the digital signal (nVIDEO) and converted to parallel light waves by the collimator lens. The beam is then
directed to the rotating tetragon mirror, where it is reflected to the f-
θ
lens and then focused onto the OPC Drum surface. The
laser beam moves across the surface of the OPC Drum in the scanning direction. Where the laser beam is applied, the negative
charge on the drum dissipates, and where the laser is not applied, the negative charge remains. This action forms a latent,
electrostatic image on the OPC Drum, corresponding to the original image.
Development
This development process uses a conventional method, where toner coats a Development Roller and transfers to the latent
image on the OPC Drum. In the Toner Cartridge, the (mono-component) toner is negatively charged by the friction between the
rotating Development Roller (Mag Roller) and the Developing Blade. This combination and the rotation of the Mixing Blade
transfers the toner from the reservoir and forms a brush effect on the Mag roller. Where the magnetic brush lightly touches the
OPC Drum, the negatively charged toner is attracted to the latent image on the drum, forming a mirror image of the original on
the drum. Any remaining toner is removed from the Mag Roller by the Developing Blade and is recycled back into the toner
reservoir. A bias voltage of approximately 1.5 kVACp-p at 1.87 kHz, riding on a -300 VDC bias is applied to the magnetic brush
to achieve maximum print quality.
The Toner Sensor (513), a magnetic sensor, detects the remaining quantity of toner in the Toner Cartridge. When the “TONER”
lamp starts to blink, there is still enough toner left in the cartridge to print 100 pages (based on ITU-T Image No.1). When the
toner runs out, the display will show: “OUT OF TONER & INFO CODE 041” and the machine is disabled from
printing any copies.
The Toner Cartridge consists of OPC Drum, Bias Charge Roller, Development Roller, Developing Blade, Cleaning Blade,
Mixing Blades and Toner Waste Box. The OPC Drum is an aluminum cylinder coated with an OPC (Organic Photo Conductor)
sensitive material. This surface is photoelectric (retains the charge in the dark and releases the charge in the light). The
potential differences on the surface (a static latent image) form a printed image. The Bias Charge Roller provides a uniform
charge on the OPC Drum surface. The Development Roller supplies toner to the drum by rotating over the magnet. The
Developing Blade evens the toner on the Development Roller surface and also charges the toner by friction. The Cleaning
Blade cleans by scraping the remaining toner off the OPC Drum surface after transfer.