Ricoh B234 Service Manual page 856

DEVELOPMENT
V Update
REF
To update V (the TD sensor reference voltage), V
REF
of the copy job, if 10 or more copies have been made since the last V
This compensates for any variations in the reflectivity of the pattern on the drum or
the reflectivity of the drum surface. The 10-copy interval can be changed using
SP2210.
V is also updated during process control initial setting.
REF
If the reading of the ID sensor becomes abnormal while checking the ID sensor
pattern, SC400, SC401, SC402, or SC406 is logged and the toner density control
is done using TD sensor only.
V Detection
T
The toner density in the developer is detected once every copy cycle, after the
trailing edge of the image passes the development roller.
If the reading from the TD sensor, done for every page in the copy job, becomes
abnormal (Vt ≤ 0.5V or Vt ≥ 4.0V), then the machine holds the GAIN factor
constant to allow toner supply to vary with only the pixel count for the rest of the
copy job. Then at the end of the job, SC360 (Vt Above Upper Limit) or SC364 (Vt
Below Lower Limit) is generated and the machine must be repaired.
If the TD sensor needs to be replaced and none is available, the toner supply mode
can be set to image pixel count mode using SP2208.
Image Pixel Count
For each copy, the CPU adds up the value of each pixel and converts the sum to a
value between 0 and 255. (The value would be 255 if the page was all black.)
B234/B235/B236/D101/D102/D103
SP
6-94
/V is detected at the end
SG
REF
update.
SM