Xerox Phaser 3450 Service Manual page 15

4.1.2 Transfer
It consists of a PTL (Pre-transfer Lamp) and a transfer roller. A PTL sheds light on an OPC drum, lowers
an electric potential of an OPC drum's surface, and improves the efficiency of the transfer.
A transfer roller transfers toner on an OPC drum to the paper.
Life span : Print over 60,000 sheets (In 15~30(C)
4.1.3 Driver Ass'y
By driving the motor, the system takes power. It is consisted of a main motor for feeding and a developer,
and sub-motors for fuser and duplex reverse turn.
4.1.4 Fuser
It is consisted of a heat lamp, heat roller, pressure roller, thermistor and thermostat. It sticks the toner on a
paper by heat and pressure to complete the printing job.
1) Thermostat
When a heat lamp is overheated, a Thermostat cuts off the main power to prevent over-heating.
3) Heat roller
The heat roller transfers the heat from the heat lamp to apply a heat on the paper. The surface of a
heat roller is coated with Teflon, so toner does not stick to the surface.
4) Pressure roller
A pressure roller mounted under a heat roller is made of a silicon resin, and the surface also is coated
with Teflon. When a paper passes between a heat roller and a pressure roller, toner adheres to the sur-
face of a paper permanently.
5) Items for safety
Protecting device for overheating
- 1st protection device : Hardware cuts off when overheated
- 2nd protection device : Software cuts off when overheated
- 3rd protection device : Thermostat cuts off main power.
Safety device
- A fuser power is cut off when a front cover is opened
- Maintain a temperature of fuser cover's surface under 80(C for user, and attach a caution label at
where customer can see easily when customer open a rear cover.
4.1.5 LSU (Laser Scanner Unit)
It is the core part of the LBP which switches from the video data received to the controller to the electrostat-
ic latent image on the OPC drum by controlling laser beam, exposing OPC drum, and turning principle of
polygon mirror. The OPC drum is turned with the paper feeding speed. The /HSYNC signal is created
when the laser beam from LSU reaches the end of the polygon mirror, and the signal is sent to the con-
troller. The controller detects the /HSYNC signal to adjust the vertical line of the image on paper. In other
words, after the /HSYNC signal is detected, the image data is sent to the LSU to adjust the left margin on
paper. The one side of the polygon mirror is one line for scanning.
Summary of product
Service Manual
4-3