Principles Of Developing - Printronix L5000 Series Maintenance Manual

To accomplish ultra-fine developing, the printer employs a two-component fine-grain
developer which consists of a magnetic toner having a particle diameter of about 8
microns and a carrier having a particle diameter of about 40 microns. Note that the
carrier is resin-coated to appropriately weaken its magnetism. The developing unit is
constructed so that a predetermined amount of toner is always kept in the agitation
chamber and that toner is replenished as needed from the toner cartridge. When the
toner cartridge is inserted into the developing unit and rotated 180 degrees, the toner
in the cartridge falls into the toner hopper.
When the toner density sensor detects any toner density insufficiency in the agitation
roller section, the toner supply roller (sponge) rotates to drop the toner into the
agitation chamber. The agitation roller then mixes the toner with the carrier, and the
resultant mixture is fed to the photoreceptor drum surface via the gap between the
developing roller and doctor blade. In this process, the toner is positively charged
because of the friction between the toner and carrier.

Principles of Developing

The developing roller consists of the following rotary inner-pole magnet and sleeve.
Note that a developing bias is applied to the developing roller. The developing bias is
obtained by superimposing a 1.5 kVp-p, 2 kHz AC bias upon a +300 V DC bias as
illustrated below.
5–12
1500 V
300 V
-450 V
Principles of Operation