Brother International HL-720 Service Manual - Page 45

Drum Unit, Photosensitive Drum, Primary Charger, Developer Roller, Transfer Roller, Cleaner Roller

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2.4 Drum Unit 2.4.1 Photosensitive Drum Generates the latent electrostatic image and develops the image on the drum surface. 2.4.2 Primary Charger Forms a uniform charge on the drum surface. (1) Corona wire Generates ion on the drum. (2) Grid Spreads the ion evenly over the drum. 2.4.3 Developer Roller Develops the latent electrostatic image on the drum surface by the toner. 2.4.4 Transfer Roller Transfers the toner image to the paper from the drum surface. 2.4.5 Cleaner Roller Removes and exhausts the toner remaining on the drum surface. 2.4.6 Erase lamp Discharges the electrostatic latent image on the drum. 2.5 Print Process 2.5.1 Charging The drum is charged to approx. +1000V by ion which is generated by the primary charger. Ion is generated by an ionization of the corona wire, which applied DC bias from High-voltage Power Supply. The flow of ion is controlled by the grid to be distributed evenly on the drum surface. The other end of the grid is generated to approx. 280V by the voltage regulator. 280V Passive Type Voltage Regulator Voltage Regulator +++-+--+--+- 1000V - + -- - ++ - + ++ + + + + + ++ + + Aluminum pipe Organic Photoconductor layer Grid HVPS Corona wire Fig. 2.31 Drum The primary charge uses a corona wire, but since the charging terminal of the drum is a positive terminal , only less than 1/10 of the usual quantity of ozone is generated. The level of ozone expelled from the printer is therefore not harmful to the human body. Applicable safety standards have been complied with. II-28

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II-28
2.4
Drum Unit
2.4.1
Photosensitive Drum
Generates the latent electrostatic image and develops the image on the drum
surface.
2.4.2
Primary Charger
Forms a uniform charge on the drum surface.
(1)
Corona wire
Generates ion on the drum.
(2)
Grid
Spreads the ion evenly over the drum.
2.4.3
Developer Roller
Develops the latent electrostatic image on the drum surface by the toner.
2.4.4
Transfer Roller
Transfers the toner image to the paper from the drum surface.
2.4.5
Cleaner Roller
Removes and exhausts the toner remaining on the drum surface.
2.4.6
Erase lamp
Discharges the electrostatic latent image on the drum.
2.5
Print Process
2.5.1
Charging
The drum is charged to approx. +1000V by ion which is generated by the primary
charger. Ion is generated by an ionization of the corona wire, which applied DC
bias from High-voltage Power Supply. The flow of ion is controlled by the grid
to
be distributed evenly on the drum surface. The other end of the grid is generated to
approx. 280V by the voltage regulator.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
++
+
+
-
-
-
-
-
-
-
-
---
Fig. 2.31
The primary charge uses a corona wire, but since the charging terminal of the
drum is a positive terminal , only
less than 1/10 of the usual quantity of ozone is
generated. The level of ozone expelled from the printer is therefore not harmful to
the human body. Applicable safety standards have been complied with.
Aluminum pipe
Organic Photoconductor layer
Drum
Passive Type
Voltage Regulator
Voltage
Regulator
Corona wire
1000V
280V
Grid
HVPS