Image forming apparatus

Abstract

A loosening fan provided in an air blowing unit blows at sheets stacked on a tray to loosen the sheets. When, during a sheet feeding operation, a multi-feed detection unit detects a multi-feed condition, the loosening fan is controlled such that an air pressure that enables the sheets to be loosened is obtainable. Therefore, the occurrence of multi-feed conditions can be reduced.

1 . (canceled) 
     
     
         2 . An image forming apparatus comprising:
 a tray;   an image forming unit; and   a sheet feeding device configured to feed a sheet to the image forming unit after loosening sheets stacked on the tray by blowing air on the sheets, the sheet feeding device comprising:
 an air blowing unit including a fan configured to blow air on the sheets stacked on the tray; 
 a multi-feed detection unit configured to detect a multi-feed condition in which a plurality of sheets are fed at a time; 
 a rotation-frequency measuring unit configured to measure the rotation frequency of the fan; 
 a determining unit configured to determine, based on a signal from the rotation-frequency measuring unit, whether the rotation frequency of the fan falls within a predetermined target rotation-frequency range at which an air pressure that enables sheets to be loosened is obtainable; and 
 a control portion configured to control the fan based on a determination by the determining unit, 
   wherein during the adjustment of the rotation frequency of the fan, when the determining unit determines that the rotation frequency of the fan does not fall within the predetermined target rotation-frequency range, the control portion controls the fan so that the rotation frequency of the fan is adjusted on which the rotation frequency of the fan falls within the predetermined target rotation-frequency range.   
     
     
         3 . The image forming apparatus according to  claim 2 , wherein the sheet feeding device comprises:
 a counting unit configured to count the number of occurrences of a multi-feed condition detected by the multi-feed detection unit,   wherein the control portion controls such that the sheet feeding device is configured to, when the multi-feed detection unit detects a multi-feed condition, stop a feeding job depending on a count value counted by the counting unit, adjust the rotation frequency of the fan, and then restart the feeding job.   
     
     
         4 . The image forming apparatus according to  claim 2 , wherein the sheet feeding device is configured to adjust the rotation frequency of the fan in a state in which no obstacle is present in front of an air outlet of the air blowing unit.