Ricoh A028 Service Training Manual page 111

1 July 1994
How an ID sensor pattern is produced
In the ID sensor mode, the OPC is charged at a certain
potential by the charge corona unit. A 420 x 50 mm area
is left by erasing unwanted areas. The area is
developed as an ID sensor pattern.
To make the OPC potential to make the ID sensor
pattern steady, the pattern is formed as follows:
1.
The OPC is charged using a grid voltage which is about 10 steps lower than that during
copying. The actual grid voltage is the same value that was used for the grid voltage the
preceding time that the ID sensor pattern was made. (That value was stored in memory.)
2.
The OPC potential is measured by the potential sensor. The measured value is compared
with the selected ID sensor pattern level in the service tool [4-02]. If the measured value
differs from the selected ID sensor pattern level, OPC is erased and charged a second time.
For the second charge, the grid voltage is compensated so as to be the same potential as
the selected pattern level. The electric latent image of a 420 x 50 mm area is formed by
erasing unwanted areas, and it is developed to produce the ID sensor pattern.
3.
When the drum potential is the same as the selected ID sensor pattern level, the second
charge is not done and the first charge is used to make the ID sensor pattern.
Erase unit
Dummy charge
Potential measurement
Does it differ
No
from the selected
ID sensor pattern
level?
Yes
Erase
Grid output
compensation
Charge
2-75
Charge corona unit
OPC potential sensor
Erase
(420 x 50 mm left)
Development
Toner Density Control
ID sensor