Sharp AR-280 Service Manual page 179

AR-335
[12] OPERATIONAL DESCRIPTION
Correcting operation in the image forming section (Process correction operation)
1. Outline and purpose
The operations of the image forming section are corrected in order to maintain stable and high-quality print even though any changes occur in the
temperature, humidity, consumable parts characteristics, engine conditions, or other environmental conditions.
In concrete, the correction is performed by controlling various control parameters related to the image forming section (process) operations.
With the above correction operations, stable print quality is always provided, reducing service calls and service works.
2. Image forming section correction operation (Process correction operation)
There are following items of the image forming section correction operations (process correction operations).
a. List
Image forming section correction operations (process correction operations) list
Item No. Correction operations
1 Image density sensor sensitivity
correction (Calibration) (Gain
adjustment)
2 OPC drum marking sensor sensitivity
correction
3 Developing bias voltage correction
Laser beam power correction 1
4
Laser beam power correction 2
Main charger grid voltage correction 1
5
Main charger grid voltage correction 2
6 Toner concentration correction
* 1 During warm-up after turning on the power.
During warm-up after cancelling SIM 7-1, 24-7, 25-2, 44-2.
After completion of printing when the accumulated print time reaches 30 min from the previous correction.
When the next print is made when non-print status continues one hour.
3. Details
A. Operating conditions and timing of the image forming section correction operation
(Process correction operation)
The image forming section correction operation (process correction operation) is performed under the following conditions and timing.
1) During warm-up after turning on the power.
2) During warm-up after cancelling SIM 7-1, 24-7, 25-2, 44-2.
3) After completion of printing when the accumulated print time reaches 30 min from the previous correction.
4) When the next print is made when non-print status continues one hour.
1/21/1999
Purpose, effect
Allows the image density sensor to always
detect the correct image patch density.
Allows the OPC drum marking sensor to
always detect the OPC drum marking
normally.
Prevents against density change and
background copy.
Prevent against a decrease in print density
due to OPC drum membrane decrease.
Outputs the laser beam power
corresponding to the main charger grid
voltage (to maintain the constant voltage).
Corrects a decrease in the charging voltage
due to the OPC drum membrane decrease,
maintains the correct density of print and
prevent against background copy.
Maintains the relations between the
developing bias voltage and the main
charger grid voltage at constant (to prevent
against background copy).
Maintains the normal toner concentration to
maintain the proper density of print and
prevent against background copy.
12 – 1
Execution conditions, operating timing
Before process correction operation
* 1
* 1
Specified rotating time of the OPC drum
(Every 20,000 sec)
Immediately after correction of the main
charger grid voltage (*1)
Specified rotating time of the OPC drum
(Every 20,000 sec)
Immediately after correction of the
developing bias voltage (*1)
When the developing bias voltage
correction is performed for the voltage
higher than the specified level is made
immediately after the developing bias
voltage correction. (*1)