Toshiba 4560, Service Manual

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4560/4570 FUSER 12 - 2 Nov. 1997 © TOSHIBA
12.2 Description of Operations
(1) Fuser unit
Heat and pressure are applied to the paper which has been separated from the drum and trans-
ported into the fuser unit and the toner image is fixed there. Steady pressure is applied always to the
upper and lower rollers by springs and they are rotated by the main motor. (The upper roller (heat
roller) has a heater lamp, but it does not rotate.)
The paper which has been fixed is smoothly removed from the heat roller by the use of the separa-
tion claws.
The detection unit monitors the heat roller temperature using a thermistor, and when the temperature
becomes abnormally high, the power supply to the heater lamp is stopped by a thermostat.
(2) Paper-exit unit
The upper and lower exit rollers rotate using the gear drive from the fuser unit.
The paper which has completed the fixing process exits smoothly onto the receiving tray through the
upper and lower exit rollers.
12.3 Functions of Each Part
(1) Heater lamp
This halogen lamp is located inside the heat roller and applies heat to the heat roller. The heater lamp
is secured as it is while the heat roller rotates.
(2) Heat roller
This roller is made of aluminum whose heat conductivity is relatively good, and has heat applied by
the heater lamp. Steady pressure is applied to both the heat and pressure rollers (mentioned later).
Fixing is performed by the transfer paper to be passed through between the two rollers as above so
that the toner image faces the heat roller. The toner is fused by the heat roller, the heat conductivity
rate is increased by the pressure roller, causing the toner to permeate the paper fiber. However,
during this process, a problem may occur. That is, because the toner is fixed by contacting with the
heat roller, the toner may adhere to the roller (called “offset phenomenon”). Therefore, for easier
removal of the toner from the heat roller, a Teflon coating has been applied on the surface of the heat
roller.
(3) Pressure roller
This is made of rubber for smooth application of pressure to the heat roller. The pressure roller
always has pressure applied by springs.
(4) Heat roller separation claws/pressure roller separation claws
By the use of the heat roller separation claws/pressure roller separation claws, the paper which has
been fixed to the both heat and pressure rollers is smoothly removed.