Gestetner A265, Service Manual

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DEVELOPMENT
A265/A267 2-48 SM
Toner density sensor initial setting
The TD sensor initial setting procedure is performed automatically when the new
PCU is installed in the machine. During TD sensor initial setting, the TD sensor is
set so that the TD sensor output to the value of SP2-926 (default: 2.3V). This value
will be used as the standard reference voltage (Vts) of the TD sensor.
Toner density measurement
Toner density in the developer is detected once every copy cycle. The sensor
output voltage (Vt) during the detection cycle is compared with the standard
reference voltage (Vts) or the toner supply reference voltage (Vref).
Vsp/Vsg detection
The ID sensor detects the following voltages.
•
Vsg: The ID sensor output when checking the drum surface
•
Vsp: The ID sensor output when checking the ID sensor pattern
In this way, the reflectivity of both the drum surface and the pattern on the drum are
checked. This compensates for any variations in the reflectivity of the pattern on
the drum or the reflectivity of the drum surface.
The ID sensor pattern is made on the drum by charge roller and laser diode.
Vsp/Vsg is not detected every page or job; it is detected at the following times to
decide Vref.
•
During warming up at power on
•
If the machine starts warming up after a certain time (default: 30 minutes)
has passed since entering night mode or low power mode
The 30-minute interval can be changed using SP2-995.
Toner supply reference voltage (Vref) determination
The toner supply reference voltage (Vref) is the threshold voltage for the toner
supply determination. Vref is determined using the following data:
•
ID sensor output (Vsp/Vsg)
•
(Vts or the current Vref) - Vt
Toner supply determination
The reference voltage (Vts or Vref) is the threshold voltage for determining whether
or not to supply toner. If Vt becomes greater than the reference voltage, the
machine supplies additional toner.
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