Recording medium detecting apparatus

摘要

A recording medium detecting apparatus detects the fact that a recording medium has been conveyed to an image forming part of a laser beam printer. The image forming part is provided with a driving roller for producing a rotational motion and a following roller held in pressed contact with the driving roller and consequently allowed to follow the rotational motion. The thrust of the recording medium in between the two rollers is discriminated by the detection of a change in the rotational speed of the driving roller which change is caused by the thrust of the recording medium in between the rollers. In accordance with the result of detection of this thrust, the timing for image formation in the image forming part is controlled. Thus, the arrival of the recording medium at a prescribed destination can be detected without requiring use of a sensor or a switch. Where a plurality of recording media are conveyed in a superposed state, the number of these recording media can be discriminated by detecting the amount of change in the rotation speed. The display part for displaying the residual amount of recording media is controlled in accordance with the number of recording media involved in the thrust. The display part tells the operator the residual amount of recording media.