Surface - Page 61

Confidential

3 - 1 6

3.  The laser beams reflected by the reflection mirror go straight toward the exposure drum below 

it, then expose the exposure drum. 

The area exposed to the laser beam is the image to be printed.  The surface potential of the  
exposed area is reduced, forming the electrostatic image to be printed. 

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 Developing 

Developing causes the toner to be attracted to the electrostatic image on the drum so as to  
transform it into a visible image. 
The developer consists of a non-magnetic toner.  The developer roller is made of conductive  
rubber and the supply roller (which is also made of conductive sponge) rotate against each other. 
The toner is charged and carried from the supply roller to the developer roller.  The toner adheres  
to the developer roller and is conveyed to the exposure drum at an even thickness controlled by the  
blade.  The toner is nipped between the developer roller and the drum and developed onto the  
latent image on the drum.  The electrostatic field between the drum and the developer roller, which  
is DC-biased from the high-voltage power supply, creates the electrostatic potential to attract toner  
particles from the developer roller to the latent image area on the drum surface. 

1 Cycle of drum 

Surface 
potential (V) 

+897 

+400 

+150 

Drum 
sleeve 

0 

Time 

1 

2

3

(a) 

(b)

1     Primary charging 

2     Laser beam exposure and developing 

3     Transfer the image to paper 

(a) Unexposed area 

(Non image area) 

(b) Exposed area 

(Image area) 

Supply roller

Blade 

Developer roller

Exposure drum 

Corona wire 

Transfer roller