Brother 1250, HL-1030, 1240 service manual Print Process, Charging, Exposure stage

CHAPTER 3 THEORY OF OPERATION

2.6Print Process

2.6.1Charging

The drum is charged to approximately 870V 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 photosensitive drum is grounded.

Voltage Regulator

+	--
+	-							Aluminum drum sleeve	Photosensitive
+		-	---
	+			-	- - -			Organic Photoconductor layer	Drum
		+
870V			+ + + + +
					+	+	Grid
				+
					+
				+	+ +
			+ + +			+		HVPS

Corona wire

Fig. 3-34

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.

2.6.2Exposure stage

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

Drum

Laser beam

Laser detector

Paper

Laser beam

f θ lens

Polygon mirror

Laser diode

Motor

Lens

Fig. 3-35

3-26