| 摘要 |
In an image forming apparatus, change in electrical current value flowing through an exciting coil of a motor is measured for a predetermined time period, and, if a measurement result of the change in electrical current value obtained by the measuring means by the measurement for the predetermined time period exceeds a predetermined value, it is judged that loss of synchronism is generated. There are provided loss of synchronism detecting means, sheet detecting means disposed in a sheet conveying path of a sheet conveying system driven by the motor, and jam detecting means for judging that jam is generated if a sheet detecting condition of the sheet detecting means is continued for a certain time period or if the sheet is not detected by the sheet detecting means while the motor is being driven. It is judged that the jam is caused on the basis of the loss of synchronism of the motor if the jam is detected by the jam detecting means when the loss of synchronism is judged by the loss of synchronis detecting means.
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