Panasonic DX-600 Service Manual page 204

6.1.4. Printing Process Operation
Bias Transfer Roller
Laser Beam
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 1.65 kVACp-p at
1.875 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
Edition 1.0
Handle
Toner
Hopper
204
Toner Waste Box
Waste Toner
Cleaning Blade
OPC Drum
Development Roller
Developing Blade
Agitator Sweeper
Mixing Blade
DX-600/800
APR 2002