AR-C150 (serv.man5). ARC150-Basic Manual - Sharp Copying Equipment Service Manual (repair manual). Page 52

The obtained LED drive voltage (Vrefd) is used for detection of the
OPC drum marking. 

A decline in the photo sensitivity due to deterioration of the OPC drum
is corrected by increasing the laser beam power according to the
OPC drum rotating time (the degree of use) to maintain the proper
print density (prevention against a decline in the print density). 

Deterioration of the OPC drum advances in proportion to the print
quantity. 

There are following causes of deterioration of the OPC drum (decline
in sensitivity).

1) OPC drum membrane decrease (due to mechanical stress by the

cleaning blade and developer (mainly by the cleaning blade)
(partly by friction heat))

2) Photo stress due to laser beams and external lights

3) Electrical stress (high voltage) due to chargers

The laser beam power is increased according to the count value of
the OPC drum counter (time) as shown below:

The OPC drum counter is reset by executing TC 24-7.

a. Outline and purpose
The development conditions are varied by changes in the charac-
teristics of toner and developer and deterioration of developer caused
by changes in temperature and humidity. 
To solve the above problem, the developing bias voltage is varied ac-
cording to the conditions, maintaining the proper print density and
preventing against background copying.
There are following factors for changes in the development condi-
tions. 

1) Developer deterioration (Change in the developer shape caused

by friction heat and mechanical stress in the developing unit and
abrasion of the coating layer)

2) Changes in the developer characteristics caused by changes in

temperature and humidity (Changes in electrical characteristics
depending on temperature and humidity)

Deterioration of developer advances in proportion to the print
quantity.

 
b. Details of operation 

<1> In the case of color mode
(Case 1) When the OPC drum correction counter is reset with SIM 24-7, the correction conditions are initialized and correction is performed from the

developing bias voltage set with SIM 44-5. 

Sensor drive(LED) voltage

PHOTOCONDUCTOR SENSOR CALIBRATION

Sensor output

level(voltage)

V min(LED off)

5.0v

Reference

Level(3.6v)

Reference sensor drive(LED) voltage(Vrefd)

Photo conductor surface
reflection level

Step 1

Step 2

LASER BEAM POWER CORRECTION (for Photoconductor waredown correction)

[uW]

Laser beam
power

Start point(Reset by T.C24-7)

Photoconductor drum rotation time(h)

Higher

Image patch density

100

90

83

Lower

0

100

200

300

400

500

600

Develping bias voltage

Limit(-600v)

CASE 2

Y/M/C PAT TARGET
ID(Set by SIM44-4)

Limit(-125v)

Correction voltage 1(PADV1)

Correction voltage 2(PADV2)

1st stage

PTK1/BS1(ID1)

PTK2/BS2(ID2)

PTK3/BS3(ID3)

PTK1/BS1(ID1)

PTK2/BS2(ID2)

PT3/BS3(ID3)

PTK4/BS4(ID4)2

PTK5/BS5(ID5)

PTK6/BS6(ID6)

CASE 1

AR-C150

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