| 摘要 |
PURPOSE:To eliminate troubles in offset and to prevent the copy picture quality from deteriorating by powering off both heaters when the difference in detected temperature between the 1st and the 2nd temperature detecting means exceed a set value, and displaying the abnormality of the 2nd temperature detecting means. CONSTITUTION:A heat roll fixing device consists of a heat roll 10 and a pressure roll 12. The heat roll 10 is constituted by fixing halogen lamp heaters 14a and 14b differing in light emission length successively and rotating a sleeve 16 made of aluminum to an about 8mm thickness around the heaters. Then SSRs 32 and 34 are turned on and off under the control of a controller 33 to power on and off the heaters 14a and 14b. If a thermistor 26b is defective in fitting or has a break of wiring and a state of T1-T2>alpha continues for >=x seconds where T1 and T2 are detected temperatures of thermistors 26a and 26b, the SSRs 32 and 34 are both turned off to power off the heaters 14a and 14b. Consequently, the heat roll fixing device is protected to eliminate problems such as a defective in fixation, offset of a toner image, etc. |
