Toshiba e-studio550 Service Manual page 211

14. 4. 2. Heating principle of IH coil
The magnetic field is generated by applying a high frequency current to the IH coil inside the fuser
roller, which then produces the eddy current in it. When the eddy current flows, the Joule heat is
generated by the resistance element of the fuser roller, which is then heated. In the IH coil method, the
thermal efficiency is higher than the lamp method because the fuser roller is directly heated.
IH coil is divided into two parts to decrease the temperature difference between the center and both ends
of the fuser roller.
B
High frequency
power source
A
Monitoring input current
[Block diagram of high fequency power supply (IH control board)]
JUNE 2002 © TOSHIBA TEC
Center IH coil
Side IH coil
[Image of current flowing from A to B]
Smoothing circuit
T1
Current input
Monitoring input current
Current flowing on the surface of the fuser roller
Magnetic field
Eddy current
Control circuit for high frequency current
C2
C3
C1
D1
CPU
Voltage
I/F circuit on LGC board
input
14 - 5
Current flowing inside the
fuser roller
Fusr roller
IH coil
Tr1
IGBT
drive
(IGBT)
Tr2
IGBT
drive
e-STUDIO550/650/810 FUSER UNIT