Temperature control apparatus, electrophotographic apparatus, and temperature control method for heating element

1. A temperature control apparatus comprising:

a temperature sensor which detects a temperature of a heating element;

a controller for controlling heat generation of the heating element in accordance with the detected temperature, wherein the controller controls heat generation of the heating element so that the detected temperature approaches a target temperature; and

a monitoring circuit which monitors the detected temperature, and stops operation of the controller during a stop period when a predetermined operation mode is set, wherein the monitoring circuit defines, as the stop period when the predetermined operation mode is set, a period from a time point when the controller is operating and it is confirmed that the detected temperature is higher than a first reference temperature that is lower than the target temperature to a time point when the detected temperature is lower than a second reference temperature that is lower than the first reference temperature.

2. The apparatus of claim 1 , wherein the monitoring circuit sets at least one of the first reference temperature and the second reference temperature in accordance with an instruction from a user.

3. The apparatus of claim 1 , wherein the monitoring circuit decides the stop period in accordance with a cumulative time of a period during which the detected temperature exceeds a reference temperature.

4. An electrophotographic apparatus comprising:

an image forming unit which, after a toner image is formed on a printing medium, melts and fixes the toner image to the printing medium with heating by a heating element;

a temperature sensor which detects a temperature of a heating element;

a controller for controlling heat generation of the heating element in accordance with the detected temperature, wherein the controller controls heat generation of the heating element so that the detected temperature approaches a target temperature; and

a monitoring circuit which monitors the detected temperature, and stops operation of the controller during a stop period when a predetermined operation mode is set, wherein the monitoring circuit defines, as the stop period when the predetermined operation mode is set, a period from a time point when the controller is operating and it is confirmed that the detected temperature is higher than a first reference temperature that is lower than the target temperature to a time point when the detected temperature is lower than a second reference temperature that is lower than the first reference temperature.

5. The apparatus of claim 4 , wherein the monitoring circuit sets at least one of the first reference temperature and the second reference temperature in accordance with an instruction from a user.

6. The apparatus of claim 4 , wherein the monitoring circuit decides the stop period in accordance with a cumulative time of a period during which the detected temperature exceeds a reference temperature.

7. The apparatus of claim 4 , further comprising a control unit which set the predetermined operation mode in accordance with whether a predetermined condition is met.

8. The apparatus of claim 7 , wherein the control unit supplies, to the monitoring circuit, a mode signal having a first level when the predetermined operation mode is set and having a second level otherwise, and

the monitoring circuit defines, as the stop period when the mode signal has the first level, a period from a time point when the controller is operating and it is confirmed that the detected temperature is higher than a first reference temperature that is lower than a target temperature to a time point when the detected temperature sensor is lower than a second reference temperature that is lower than the first reference temperature.

9. A method for controlling temperature of a heating element comprising:

detecting a temperature of a heating element by a temperature sensor;

controlling, by a controller, heat generation of the heating element in accordance with a detected temperature, wherein the controller controls heat generation of the heating element so that the detected temperature approaches a target temperature; and

monitoring the detected temperature by a monitoring circuit and stopping operation of the controller during a stop period when a predetermined operation mode is set, wherein the monitoring circuit defines, as the stop period when the predetermined operation mode is set, a period from a time point when the controller is operating and it is confirmed that the detected temperature is higher than a first reference temperature that is lower than the target temperature to a time point when the detected temperature is lower than a second reference temperature that is lower than the first reference temperature.