Printronix L1024, Maintenance Manual

Page: 365 / 372

D–3 Appendix D – Principles of Operation
Exposing the OPC Drum (Forming the Latent Image)
Inside the lid of the printer is a modulated semiconductor laser. The beam of the laser shines on a
rotating polygonal mirror which causes the beam to scan across the OPC drum. The beam
discharges the negative potential of the drum in the pattern of the desire image. This gives the image
portion of the OPC a less negative potential than the rest of the OPC, approximately –100 volts, while
the unexposed portion of the OPC maintains approximately –700 volts. The electrical pattern formed
by this process is called the “latent image.”
This process is illustrated in Figure D–2.
– – – – – – – –
–
–
– – – – – –
Light Dark
OPC Material
High Negative Voltage Low Negative Voltage
Conductive Base Material
OPC Drum Surface
Exposed Portion
(Low Negative Voltage)
Non–exposed Portion
(High Negative Voltage)
Figure D–2. Exposing the OPC Drum