Sheet aligning device and image forming apparatus using the same

Abstract

In a sheet aligning device, a pair of first rollers provided upstream of a stopper unit moves a sheet in an axial direction thereof after a pair of second rollers provided upstream of the first rollers is separated, and is returned to its home position just after the sheet passes therethrough.

1 . A sheet aligning device comprising:
 a sheet conveying path;   a detecting unit that detects a side edge of a sheet conveyed in the sheet conveying path;   a stopper unit that is provided upstream of the detecting unit, and positions a leading end of the sheet conveyed in the sheet conveying path by opening and closing the conveying path;   a first conveying unit that is provided upstream of the stopper unit and includes a pair of first rollers, the first roller being in contact with or separated from each other;   a second conveying unit that is provided upstream of the first conveying unit and includes a pair of second rollers, the second rollers being in contact with or separated from each other; and   a lateral moving unit that moves the first rollers in an axial direction thereof based on a result indicative of a detection by the detecting unit.   
   
   
       2 . The sheet aligning device according to  claim 1 , wherein with the first rollers being separated, the second conveying unit conveys the sheet so that the sheet forms a loop between the stopper unit and the second conveying unit;
 subsequently, the first rollers are made in pressure-contact with each other, the stopper is released, and the second rollers are separated to convey the sheet and to move the first rollers in an axial direction thereof; and   after the sheet passes through the first conveying unit, the first rollers is returned to an original position thereof.   
   
   
       3 . The sheet aligning device according to  claim 1 , wherein a conveying speed of the second conveying unit is temporarily decreased upon making the sheet in contact with the stopper unit. 
   
   
       4 . The sheet aligning device of  claim 1 , further comprising a drive unit that associates an open/close operation of the conveying path by the stopper unit and contact/separation operations of the first rollers and the second rollers with one another. 
   
   
       5 . The sheet aligning device according to  claim 4 , further comprising a cam unit that is fixed on a cam shaft and performs the open/close operation and the contact/separation operations. 
   
   
       6 . The sheet aligning device according to  claim 5 , wherein the cam unit includes three cams. 
   
   
       7 . An image forming apparatus comprising:
 the sheet aligning device according to  claim 1 .   
   
   
       8 . A sheet aligning device comprising:
 a sheet conveying path through which a sheet is conveyed to an image transfer unit;   a lateral registration unit that moves in a width direction from a home position thereof to correct a misalignment of the sheet in the width direction; and   a conveying unit that conveys to the image transfer unit the sheet after the misalignment in the width direction is corrected by the lateral registration unit, wherein   the lateral registration unit moves back to the home position immediately after the sheet whose misalignment in the width direction is corrected by the lateral registration unit reaches the conveying unit.   
   
   
       9 . The sheet aligning device according to  claim 8 , further comprising a stopper unit that is capable of opening and closing the sheet conveying path and corrects an inclination of the sheet by making a leading end of the sheet in contact therewith, wherein
 the lateral registration unit includes a pair of lateral registration rollers that moves in the width direction after nipping the sheet that is in contact with the stopper unit, and   the conveying unit includes a pair of longitudinal registration rollers that is arranged downstream of the stopper unit in a conveying direction of the sheet and corrects a misalignment in the conveying direction of the sheet whose misalignment in the width direction is corrected by the lateral registration rollers.   
   
   
       10 . The sheet aligning device according to  claim 9 , wherein the lateral registration rollers move back to the home position immediately and release the nipping of the sheet immediately after the sheet whose misalignment in the width direction is corrected by the lateral registration unit reaches the longitudinal registration rollers. 
   
   
       11 . An image forming apparatus comprising:
 the sheet aligning device according to  claim 8 .