Transport monitoring control device and image forming apparatus

An image forming apparatus comprising:

• a transport unit configured to transport a recording medium, which is taken out from an accommodating unit, along a preset transport path while the recording medium is nipped by a plurality of pairs of rollers each of which is driven by a driving force of a motor;
• a transfer member serving as one of the plurality of pairs of rollers in the transport unit, wherein in a case in which facing the recording medium being transported, the transfer member transfers an image at a position where the transfer member faces the recording medium;
• and
• at least one hardware processor configured to implement:
• a detector configured to detect a waveform related to a driving current of the motor for a pair of rollers disposed upstream of the transfer member;
• an extractor configured to extract a peak waveform having an extreme point temporarily exceeding a predetermined threshold value, from among waveforms detected by the detector;
• a determining unit configured to determine whether multi-feed of the recording medium is present, based on a number of peak waveforms extracted by the extractor;
• a specifying unit configured to specify a preceding recording medium by comparing extreme points of two or more peak waveforms in a case in which the determining unit determines that the number of peak waveforms is plural and that the multi-feed is present;
• and
• a delaying unit configured to delay a transfer timing using a difference between (i) an extreme point of a peak waveform indicating that a leading end of the preceding recording medium specified by the specifying unit enters and (ii) an extreme point of a peak waveform indicating that a leading end of a recording medium to which the image is to be transferred enters,
• wherein the two or more peak waveforms are two or more electrical-current peak waveforms.