Functions - Toshiba e-STUDIO2500c Service Manual

15.3 Functions

1) Center heater lamp (LAMP1) / Side heater lamp (LAMP2)
The heater lamps are halogen lamps to apply heat to the heat roller. The fuser unit of the equipment
has 2 heater lamps installed in the heat roller and 1 in the pressure roller.
The 2 heater lamps in the heat roller have their respective functions. One has a coil wound up on its
center and this part generates heat. The other one has coils wound up on its both ends and these
parts generate heat. The one has a coil on its center is called the center heater lamp and the one
has coils on its both ends is called the side heater lamp. The heater lamps are fixed on the inside of
the heat roller to heat it up. The heater lamps do not rotate even when the heat roller is rotating.
2) Heat roller
The heat roller is an alminium roller which conducts heat generated by the heater lamp to the fuser
belt. The heat roller in this equipment is a thin roller which enhances heat conduction, and thus the
warming-up time is shortened.
3) Fuser belt
The fuser belt couples the heat roller with the fuser roller, and it conducts heat from the heat roller to
the fuser roller and paper to melt toner on the paper.
The thin fuser belt enables to reduce warming up time and mode changing time. To prevent the
fuser belt from adhering toner, the surface of the fuser belt is fluorinated.
4) Fuser roller
The fuser roller is pressed against the pressure roller with the fuser belt in-between. By this pres-
sure between the fuser roller and pressure roller, the heat conduction to the paper is enhanced so
that toner becomes easier to be melted, and melted toner is soaked into the paper. In order to
improve the fusing ability, the fuser roller with sponge surface is employed to expand the nip width.
5) Pressure roller
The pressure roller is a rubber roller which ensures proper nip width between the pressure roller and
fuser roller / fuser belt, and it is pressed on the fuser roller / fuser belt by springs in order to fuse
toner effectively to the paper.
Also, a heater lamp is fixed on the inside of the pressure roller to stabilize the surface temperature of
the pressure roller. The heater lamp does not rotate even when the pressure roller is rotating.
6) Pressure roller lamp (LAMP3)
The pressure roller lamp is a halogen lamp which is turned ON/OFF constantly to maintain the pre-
set temperature in order to stabilize the surface temperature of the pressure roller, reduce warming
up time and enhance fusing ability. Unlike the center heater lamp / side heater lamp, the whole part
of the pressure roller lamp generates heat.
7) Heat roller center thermopile (THMP1) / Heat roller rear thermopile (THMP2)
The thermopiles are high-sensitivity infrared thermistors to detect the surface temperature of the
fuser belt. Non-contact type thermistors are used in order not to damage the paper contact surface
of the fuser belt. One thermopile fixed each on the center and rear-side of the frame detects the tem-
perature of the center and edge of the fuser belt, and controls the center heater lamp / side heater
lamp.
These thermopiles detect the temperature of the fuser belt to maintain it in a certain temperature
range (actually around 160°C) between the lower limit causing the poor fusing and the upper limit
causing the high temperature offsetting. When the temperature of the fuser belt is lower than the
preset temperature, it turns ON the power supply to the heater lamps, and when it is higher than the
preset temperature, it cuts off the supply.
May 2006 © TOSHIBA TEC e-STUDIO2500c/3500c/3510c FUSER UNIT / PAPER EXIT SECTION
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