Ricoh LDD250, Service Manual

Page: 382 / 459

DRUM
C262/C265 6-60 SM
Ink Detection Board
The ink detection pins [A] function as a capacitor electrode and detect the ink
capacitance between the ink roller [B] and the doctor [C] rollers. The capacitance
level changes with the ink level. When the ink level is high, the pins touch ink, and
the capacitance increases. When the ink level is low, the pins do not touch the ink
and the capacitance therefore decreases. Consequently, by detecting the
capacitance between the pins, the ink supply motor maintains the ink level.
The display panel shows the remaining ink amount when the main switch is turned
on, if the remaining amount of ink is less than half. The remaining ink is estimated
from the number of revolutions of the ink pump. Because of this, when the user
replaces the ink cartridge, the user should install a full cartridge, or this mechanism
will not be reliable.
NOTE: User Tools – System Settings – Mode Setting – Master/Ink Remaining
Volume must be “On”. The default is “Off”.
If the ink detection pins are defective, the ink flow detector [D] acts as a back-up to
detect excess ink. This prevents excessive ink supply and ink overflow inside the
drum. When too much ink is supplied, the pin [F] of the ink flow detector moves up,
and this turns the sensor on.
C262D051.WMF
C262D052.WMF
[A]
[B]
[C]
[D]
[E]
[F]