Patent ID: 8494381

Claim:
A method for determining a malfunction in a heating unit, comprising: a temperature detection step of detecting a temperature of a heating body in the heating unit; a first malfunction determination step of, in a case where the temperature of the heating body detected when the heating body begins to be heated is lower than a first predetermined temperature, obtaining a temperature rise time from the time when the heating body begins to be heated to the time when the temperature of the heating body reaches the first predetermined temperature, and then determining whether there is the malfunction in the heating unit based on the obtained temperature rise time of the heating body via a temperature rise time obtaining unit; and a second malfunction determination step of, in a case where the temperature of the heating body detected during a time period in which the heating body is heated continually is higher than or equal to the first predetermined temperature and lower than or equal to a second predetermined temperature, calculating temperature increase rate of the heating body, and then determining whether there is the malfunction in the heating unit based on the calculated temperature increase rate of the heating body via a temperature increase rate calculation unit, wherein the first predetermined temperature is configured to separate low temperature and mid-to-high temperature.