Brother HL-1020 Drum Unit Photosensitive Drum, Primary Charger, Development Roller, Erase Lamp

2.4Drum Unit

2.4.1Photosensitive Drum

Generates the latent electrostatic image and develops the image on the drum surface.

2.4.2Primary Charger

Forms a uniform charge on the drum surface.

(1)Corona wire

Generates the ion charge on the drum.

(2)Grid

Spreads the ion charge evenly over the drum surface.

2.4.3Development Roller

Develops the latent electrostatic image on the drum surface by the addition of the toner.

2.4.4Transfer Roller

Transfers the toner image to the paper from the drum surface.

2.4.5Cleaner Roller

Removes and recycles the toner remaining on the drum surface.

2.4.6Erase Lamp

Discharges the electrostatic latent image on the drum.

2.5Print Process

2.5.1Charging

The drum is charged to approx. +1150V 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 drum sleeve is regulated to approx. 280V by the voltage regulator.

280V	Passive Type
	Voltage Regulator

Voltage Regulator

+	--
+	-	-		Aluminum drum sleeve
+
	++---- - - -			Organic Photoconductor layer
1150V		+ + + + +		Grid
		+	+ +
			+
		+	+ +
		+ + + +		HVPS
	Corona wire
			Fig. 2-37

Drum

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.

II-30