Patent ID: 7907880

Claim:
An image forming apparatus comprising: a rotating body, which conveys a recording medium and which rotates integrally with a plurality of marks provided at intervals with one another; a sensor that outputs a pulse whenever each mark is detected; an actual interval measuring unit that measures an actual interval that is an output interval of the pulse from the sensor; a selecting unit that, if a current actual interval measured by the actual interval measuring unit is within a predetermined normal range, selects the current actual interval as a feedback amount, and that, if a current actual interval measured by the actual interval measuring unit is out of the normal range, selects a mean value of a plurality of actual intervals measured in the past by the actual interval measuring unit instead of the current actual interval, as the feedback amount; a control unit that compares a target interval that is a target value of the output interval of the pulse from the sensor with the feedback amount selected by the selecting unit to control rotation of the rotating body in a feedback manner so that a deviation between the target interval and the feedback amount becomes zero; a period detecting unit that, when actual intervals measured by the actual interval measuring unit are periodically out of the normal range, detects the period at which said actual intervals are out of the normal range; an elapsed time measuring unit that measures an elapsed time after an actual interval out of the normal range is measured by the actual interval measuring unit; a supplying unit that supplies a recording medium to the rotating body; and a supply control unit that controls supply start timing of the recording medium by the supplying unit, wherein, if a remaining time, obtained by subtracting the time, taken from the start of supply of a recording medium by the supplying unit to the completion of conveyance of the recording medium by the rotating body, from the period detected by the period detecting unit, is longer than the elapsed time measured by the elapsed time measuring unit, the supply control unit starts supplying of a recording medium by the supplying unit, and the supply control unit controls supply start timing of a recording medium by the supplying unit so as to complete conveyance of the recording medium by the rotating body, during a period from when an actual interval out of the normal range is measured by the actual interval measuring unit to when another actual interval out the predetermined normal range is measured next by the actual interval measuring unit, if actual intervals measured by the actual interval measuring unit are periodically out of the normal range.