| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming device which can reduce unnecessary consumption of toner and soiling of the inside of the device by unnecessary toner without complicating mechanical structure. SOLUTION: A form deprives a contacting part of heat of a fixing roller a-23 when passes through the fixing roller a-23. Thereby temperature of the part of the fixing roller a-23 coming into contact with the form descends faster than temperature of the part not coming into contact with the form does. Accordingly when a thermistor a-27 for detecting temperature is provided at an end part of the fixing roller a-23, temperature changing way of a surface of the fixing roller a-23 varies when passing the form with different width. By using this fact, time period when the temperature of the fixing roller a-23 changes from one point to another point is measured, is compared with a prescribed threshold value and thereby whether width of the passing form is broad or narrow is judged. |
