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2.5.2 TONER DENSITY CONTROL
Overview
There are two modes for controlling toner supply: sensor control mode and image
pixel count control mode. The mode can be selected with SP2-208. The factory
setting is sensor control mode. Image pixel count mode should only be used if the
TD or ID sensor is defective and cannot be replaced immediately.
[B]
Sensor Control Mode
Introduction
In sensor control mode, the machine varies toner supply for each copy to maintain
the correct proportion of toner in the developer and to account for changes in drum
reflectivity over time. The adjustment depends on two factors.
• Amount of toner needed to print the page (based on the black pixel amount for
the page).
• Readings from the TD sensor [A] and ID sensor [B].
Sensor control mode has two phases, called 'ID sensor control' and 'TD sensor
control. In ID sensor control, V
check determines the GAIN factor in the toner supply calculation (see later in this
section). In TD sensor control mode, GAIN depends on the current TD sensor
output also (V
– V
T
REF
SM
CÓPIA NÃO CONTROLADA
[A]
/V
from the most recent ID sensor pattern
SP
SG
is used).
2-43
CÓPIA NÃO CONTROLADA
Toner Supply Clutch On Time
Calculation
Pixel Count
TD Sensor
Output (V
)
T
V T Reference
Voltage (V
)
R E F
(New V
)
R E F
V T Reference
Voltage Update
V
Update
R E F
ID Sensor Output
(V
/V
)
S P
S G
TD Sensor Initial
Setting (V
)
R E F
DRUM UNIT
G A I N
A294D644.WMF
A294/A295
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Troubleshooting
