Printing Process Operation - Panasonic DF-1100 Service Manual

Panasonic DF–1100

6.1.3 Printing Process Operation

Charge
In the dark, the Bias Charge Roller (BCR) applies a high, uniform negative charge to the surface of the OP
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 polygon mirror, where
it is reflected to the 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 1.7 kVACp–p at 1.7 kHz, riding on a –500 VDC bias is applied to the magnetic brush to achieve
maximum print quality.
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