Toner Density Detection Mechanism - Ricoh A219 Service Manual

6.3 TONER DENSITY DETECTION MECHANISM

A toner density sensor (TD sensor) [A] is used for toner density control.
The TD sensor is located under the 1st agitator [B]. The developer being
conveyed by the 1st agitator passes over the top of the sensor. As the toner
in the developer is consumed during development, the toner to carrier ratio
changes, resulting in a change in the magnetic permeability of the developer.
This in turn is converted to a corresponding voltage. The CPU monitors the
voltage to control the toner supply mechanism.
When new developer is installed, and SP66 (TD Sensor Initial Setting) is
done, the machine starts idling for developer initialization. During developer
initialization, the CPU adjusts the TD sensor control voltage so that the TD
sensor outputs 1.9 ± 0.1 V for the toner to carrier ratio of new developer
(4.0% by weight). This voltage is used as the standard TD sensor voltage.
SM
CÓPIA NÃO CONTROLADA
[A]
2-27
CÓPIA NÃO CONTROLADA
TONER SUPPLY
[B]
A219D516-2.wmf
A219