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CHAPTER 3 THEORY OF OPERATION
3-24
2.6.4
Transfer
(1) Transfer
process
After the drum has been charged and exposed, and has received a developed image, the
toner formed is transferred onto the paper by applying a negative charge to the back of
the paper. The negative charge applied to the paper causes the positively charged toner
to leave the drum, and adhere to the paper. As a result, the image is visible on the paper.
(2) Cleaning process of transfer roller
If the toner is not transferred onto the paper perfectly it is possible that there may be
residual toner on the drum which will adhere to the transfer roller. The transfer voltage
changes to a positive voltage during non-printing rotation of the drum. Therefore the
transfer roller is cleaned by returning the positively charged toner adhering to the transfer
roller onto the photo-conductive drum.
2.6.5
Fixing stage
The image transferred to the paper by static electricity is fixed by heat and pressure when
passing through the heat roller and the pressure roller in the fixing unit. The thermistor keeps
the surface temperature of the heat roller constant by detecting the surface temperature of the
heat roller and turning on or off the halogen heater lamp.
Fig. 3-32
First eject roller
Thermistor
Pressure roller
Heat roller
Summary of Contents for HL-1240
Page 1: ......
Page 45: ...CHAPTER 3 THEORY OF OPERATION 3 7 Fig 3 6 ...
Page 102: ...CHAPTER 4 DISASSEMBLY AND RE ASSEMBLY 4 38 ...
Page 110: ...CHAPTER 5 PERIODIC MAINTENANCE 5 8 ...
Page 176: ...CODE UK4352000 B512040CIR 1 2 A 18 NAME Appendix 10 Main PCB Circuit Diagram HL 1240 1 2 ...
Page 177: ...Appendix 11 Main PCB Circuit Diagram HL 1240 2 2 CODE UK4352000 B512040CIR 2 2 A 19 NAME ...
Page 178: ...Appendix 12 Main PCB Circuit Diagram HL 1250 1 5 CODE UK4361000 B512049CIR 1 5 A 20 NAME ...
Page 179: ...Appendix 13 Main PCB Circuit Diagram HL 1250 2 5 CODE UK4361000 B512049CIR 2 5 A 21 NAME ...
Page 180: ...CODE UK4361000 B512049CIR A 22 NAME Appendix 14 Main PCB Circuit Diagram HL 1250 3 5 ...
Page 181: ...CODE UK4361000 B512049CIR 4 5 A 23 NAME Appendix 15 Main PCB Circuit Diagram HL 1250 4 5 ...
Page 182: ...CODE UK4361000 B512049CIR 5 5 A 24 NAME Appendix 16 Main PCB Circuit Diagram HL 1250 5 5 ...
Page 183: ...Appendix 17 Engine PCB Circuit Diagram CODE UK4444000 B512059CIR A 25 NAME ...
Page 192: ...INDEX vi ...
Page 321: ...A 12 HP LaserJet IIP HP LaserJet 6P HL 1250 only ...
Page 323: ...A 14 HP LaserJet IIP 6P EPSON FX 850 IBM Proprinter XL EPSON FX 850 ...