Ricoh A230, Руководство по обслуживанию, Страница: 105 / 1134

DEVELOPMENT
2-42
A230/A231/A232 SM
Toner supply motor on time calculation
The toner supply motor on time is decided using the following formula:
.........................................................................................................(1)
.........................................................................................................(2)
NOTE: 1) The toner supply rate can be changed using SP2-209.
2) K = Toner supply rate coefficient (0.25 ~ 3.0: default = 3.0).
3) The bracket (2) in the above formula is only used if Vtref < Vt.
4) The maximum toner supply motor on time is 1.2 s.
Vsp and Vsg detection
The ID sensor (at the lower right area of the drum) 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 the charge roller and laser diodes.
Vsg/Vsp is detected every 10 copies to decide the new Vtref. The Vsg/Vsp
detection period can be changed using SP2-210 (the default is 10).
New Vtref determination
Even if the toner concentration in the developer is kept constant by checking the
TD sensor, the toner potential (chargeability) and the image density both change
with humidity and the amount of toner on the carrier. Therefore, the actual image
density, using the ID sensor output, is also used as one of the factors for deciding
the new Vtref which is used for toner density control.
The new Vtref is determined using the following data.
•
Vtref – Vt(10)
•
Vsp/Vsg
From this point, toner density control is done using the new Vtref.
Image Pixel Count Control Mode.
This mode should only be used as a temporary measure while waiting for
replacement parts, such as a TD sensor. This mode controls the toner supply
amount using the same formula for the toner bottle motor on time. However, the
GAIN value is fixed at 1, and the other coefficients, such as “K”, “toner supply rate”
keep the values that they had when the toner density control mode was changed
over to image pixel count mode.
0.7 mg/cm
2
x Image Pixel Count x Gain Toner (Vt-Vtref x 10,000
Toner Supply Rate x K Toner Supply Rate x K
+
(
255 - Image Pixel Count) x Gain
255 6