DOWNLOAD Panasonic FP-7742 / FP-7750 (serv.man2) Service Manual ↓ Size: 2.32 MB | Pages: 127 in PDF or view online for FREE

3-20

2)

Fusing

The fuser unit makes the image permanent by fusing the toner with the heat

of heat roller and the pressure of pressure roller.

• The upper heat roller of the fuser unit  is excellent in toner release

characteristics and has applied a treatment to enhance the durability and

antistatic nature of the finish.

• The heat roller contains two halogen lamps. Two halogen lamps (main heater

lamp and sub heater lamp) are used to reduce the time for warming up after

turning ON.

• The temperature sensor (thermistor) which touches the top of heat roller controls

the heat roller temperature to the specified value.

• The fuser thermostat which is installed on the top of heat roller prevents

abnormal temperature rise of the heat roller.

• The pressure roller under the fuser unit is the silicone rubber roller and is

covered with a fluorine plastic tube to enhance the durability of the roller.

• The pressure roller applies pressure to the heat roller with the pressure

spring to form a nip width which presents the necessary time for fusing.

• The fuser unit is driven by the main motor which is transmitted to the fuser

drive gear via respective gears.

• Fuser separation finger

    To prevent paper rolling around the heat roller and the pressure roller during

fusing, the upper fuser separation fingers and the lower separation fingers

touch the respective rollers to separate the paper from the rollers mechanically

if neccessary.

Sub Assemblies

3-21

3)

Driving of fuser unit

• For fuser drive, the main motor revolution is transmitted to respective gears

and then to the heat roller via the fuser coupling gear to drive the heat roller.

• For cleaning web drive, after the speed of the heat roller gear is reduced the

web reduction gear via web coupling gear, it is transmitted to the web drive

gear to drive the web roller.

• The paper exit sensor lever detects the paper exiting the fuser unit.

4)

Operation of cleaning web

The cleaning web which touches the top of heat roller to clean the roller, does

so during the copy cycle.

• The cleaning web of rolled unwoven cloth  which is impregnated with silicone

oil supplies silicone oil to the heat roller and the pressure roller to prevent the

offset of toner and marking on copy  at  the fuser unit.

• The cleaning web is driven by the heat roller gear and the reduction gear and

is advanced very slowly during the main motor drive.

• The cleaning web has a red marking on the web near the end to check the end

of web visually.

Web drive gear

Cleaning web roller

Paper exit sensor
lever

Pressure roller

Heat roller

Middle gear

Fuser lamp

Heat roller gear

Heat roller bearing

Web connecting gear

Fuser coupling gear

3-22

5)

Temperature control
The heat roller is provided with two halogen lamps (main heater lamp and sub
heater lamp). The main heater lamp turns ON during warming up and copying
operation.
To control the maximum power consumption, the sub heater lamp turns ON
during warming up and after release of pre-heat mode only in order to reduce
the warming up time of fuser unit.
The temperature control in the copying operation and the standby is done by
the main heater lamp.

•

Sequence

a) When turning ON the power, the main heater lamp and the sub heater lamp

turns ON, which  heats the heat roller.

b) At a specified temperature, the main motor turns on and the heat roller and

the pressure roller rotate. After all copy quality standards are set, the main
motor turns off. When the heat roller temperature reaches the specified
value, the machine is ready.

c) Afterwards, the thermister detects the temperature of heat roller. The heat

roller keeps the temperature to the specified value by turning on/off the main
heater lamp.

(Note)
•

When the temperature of heat roller surface does not reach the specified value
in the specified time from power ON, the error E4-01 is indicated.

•

If when the power is turn ON in an absolutely frozen condition of fuser roller
(a very cold morning) or copies are continuously made, the operation of
main heater lamp is inadequate. In this case, the number of copies per min.
will be reduced (no change for process rate)to increase fusing time.

When the temperature of the heat roller surface rises enough, the machine
speed will return to the regular number of copies per min.

(°C)

190

ON

Switch

Print key

Energy

Saver ON

Energy

Saver OFF

Copy 

complete

Warm-up 

complete

Heat roller surface temperature

ON

0

175

Time

210 sec.

Main motor
Main lamp
Sub lamp

Sub Assemblies

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6)

Exit/2 sided copy switching

• The paper transferred from the fuser unit either exits by the paper exit selection

guide or is transferred to the ADU. The switching solenoid mounted on the

copier frame operates the paper exit selection guide via a switching lever.

Paper exit selection guide

ADU guide roller

Solenoid

Paper exit roller