Ricoh FT6645 Manual page 39

PROCESS CONTROL
<Toner Supply Clutch on Time>
To stabilize toner concentration, toner supply amount (toner supply clutch on
time) is controlled by referring to V
The toner supply amount is calculated at every copy. The toner supply
amount is determined by using the following factors.
V – V
REF
V – V
REF
Previous Copy
By referring to these factors, the machine recognizes the difference between
the current toner concentration and the target toner concentration. The
machine also understands how much toner concentration has changed and
predicts how much the toner supply amount will probably change.
By changing the toner supply amount precisely, toner concentration (image
density) is kept at a constant level.
Since the toner supply clutch on time updating is under fuzzy control, the
relation among V
formula.
<V Correction>
REF
The image on the OPC drum changes due to variation of toner chargeability
(influenced by the environment) even if the toner concentration is constant.
The image density sensor (ID sensor) directly checks the image on the OPC
drum and shifts V
OPC drum constant, as explained in the next section.
NOTE: 1. Toner end condition is detected by the toner end sensor (see the
development section for details).
2. The toner supply clutch turns on at the intervals between each
copy process while image development is not performed.
TD
'
TD
V '
TD
Last Copy
V
, V ', V cannot be expressed by a simple algebraic
TD TD REF
data (under fuzzy control) to keep the image on the
REF
and V .
REF TD
(V ' = V of the previous copy cycle)
TD TD
V
TD
REF
2-14
23 April 1993
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