| 摘要 |
A thermal fixing device which fixes a toner picture of a medium. A control means (32) which compares a temperature of a heat roller (20), sensed by a thermosensor (22), with a predetermined temperature and controls switch-on/off of a current supplied to the heating member of the heat roller (20) is provided. When the current is switched off, the control means (32) supplies forcibly a current to the heating member to the extent of not obstructing the fall of the surface temperature of the heat roller (20). The decline of the resistance of the heating member, therefore, can be avoided while the essential temperature control is maintained. With this constitution, the temperature decline of the heating member can be reduced regardless of the temperature decline of the heat roller, the resistance decline of the heating member can be reduced and, even if a current is supplied by the turning-on of the current supplied to the heating member, a rush current can be suppressed. Flickers of a fluorescent lamp, etc., therefore, can be avoided without using a power thermister and without reducing a power value.
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