3.2.2.7 Print process; 3.2.2.7 Print - Page 60

Confidential

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3.2.2.7 Print 

process 

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 Charging 

The drum is charged to approximately 900V by an ion charge which is generated by the primary  
charger.  The charge is generated by ionization of the corona wire, which has a DC bias from the  
high-voltage power supply applied to it.  The flow of the ion charge is controlled by the grid to  
ensure it is distributed evenly on the drum surface.  The aluminum drum sleeve in the exposure  
drum is grounded. 

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The primary charge uses a corona wire, but since the drum is positively charged, only less than  
1/10 of the usual quantity of ozone is generated compared with the negatively charged drum.  The  
level of ozone expelled from the printer is therefore not harmful to the human body.  Applicable  
safety standards have been complied with. 
 
 

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 Exposure 

stage 

After the drum is positively charged, it is exposed to the light emitted from the laser unit. 

< Laser exposure unit > 

1.  The laser beam radiated from a laser diode inside the laser unit are concentrated into a  

constant width by a slit in the CO lens cell and then reflected by a polygon mirror rotating at  
high speed. 

2.  The laser beam reflected by the polygon mirror are refracted by the theta lens and radiated  

from the right through to the left end of the reflection mirror as the polygon mirror rotates. 
At this time, blur of the vertical direction of the laser beam by inclination of a polygon mirror  
is corrected by passing a CYL lens. 

Exposure
drum 

Aluminum drum sleeve
Organic photoconductor layer 

Grid 

Corona wire 

HVPS 

Current 
circuit 

Polygon mirror 

Drum

Paper 

Laser beam 

f 

θ

 lens

Motor

CO lens 

Laser diode 

Laser detector 

Laser beam