Sheet conveying device, image forming apparatus, and method of detecting double-feed of sheet

Abstract

According to an embodiment, a sheet conveying device includes: a first roller configured to correct a tilt of a sheet to be conveyed; a first detecting unit located further on an upstream side in a conveying direction of the sheet than the first roller and configured to detect information concerning double-feed of the sheet; a second roller configured to convey the sheet to the first roller; a driving unit configured to drive the second roller; and a controller configured to control the driving unit to thereby temporarily stop the conveyance of the sheet in order to perform the detection by the first detecting unit in a state in which an end of the sheet on a downstream side in the conveying direction of the sheet is located further on the upstream side in the conveying direction of the sheet than a nip position of the first roller.

1 . A sheet conveying device comprising:
 a first roller configured to correct a tilt of a sheet to be conveyed;   a first detecting unit located further on an upstream side in a conveying direction of the sheet than the first roller and configured to detect information concerning double-feed of the sheet;   a second roller configured to convey the sheet to the first roller;   a driving unit configured to drive the second roller; and   a controller configured to control the driving unit to thereby temporarily stop the conveyance of the sheet in order to perform the detection by the first detecting unit in a state in which an end of the sheet on a downstream side in the conveying direction of the sheet is located further on the upstream side in the conveying direction of the sheet than a nip position of the first roller.   
     
     
         2 . The device according to  claim 1 , further comprising a second detecting unit located between the second roller and the first detecting unit and configured to detect entrance of the sheet, wherein
 the controller starts, when the second detecting unit detects the entrance of the sheet, control for stopping the sheet in a position of the detection by the first detecting unit.   
     
     
         3 . The device according to  claim 2 , wherein
 the driving unit includes:
 a pulse motor; and 
 a driver for the pulse motor, and 
   the controller stars, when the second detecting unit detects the entrance of the sheet, counting of a number of pulses output to the driver and stops the sheet in the position of the detection by the first detecting unit on the basis of a result of the counting.   
     
     
         4 . The device according to  claim 1 , wherein the first detecting unit is a non-contact detecting unit. 
     
     
         5 . The device according to  claim 4 , wherein
 the first detecting unit includes:
 an ultrasound generating unit configured to generate ultrasound; and 
 an ultrasound receiving unit configured to receive the ultrasound generated by the ultrasound generating unit, and 
   the ultrasound generating unit and the ultrasound receiving unit are opposed to each other across a conveying path for the sheet.   
     
     
         6 . The device according to  claim 5 , wherein the ultrasound generating unit is located further downstream in the conveying direction of the sheet than the ultrasound receiving unit. 
     
     
         7 . The device according to  claim 2 , wherein the second detecting unit is located below a conveying path for the sheet . 
     
     
         8 . The device according to  claim 1 , further comprising a third roller configured to pick up the sheet to the second roller, wherein
 the second and third rollers are connected by a transmission mechanism.   
     
     
         9 . The device according to  claim 8 , wherein the second roller is opposed to a fourth roller, the fourth roller inhibits double-feed of the sheet picked up by the third roller. 
     
     
         10 . An image forming apparatus comprising:
 a document conveying unit including:
 a first roller configured to correct a tilt of an original document to be conveyed; 
 a first detecting unit located further on an upstream side in a conveying direction of the original document than the first roller and configured to detect information concerning double-feed of the original document; 
 a second roller configured to convey the original document to the first roller; and 
 a driving unit configured to drive the second roller; 
   a reading unit configured to optically read the original document conveyed by the document conveying unit;   an image forming unit configured to form an image on a sheet on the basis of image data read by the reading unit; and   a controller configured to control the driving unit to thereby temporarily stop the conveyance of the original document in order to perform the detection by the first detecting unit in a state in which an end of the original document on a downstream side in the conveying direction of the original document is located further on the upstream side in the conveying direction of the original document than a nip position of the first roller.   
     
     
         11 . The apparatus according to  claim 10 , wherein
 the document conveying unit further includes a second detecting unit located between the second roller and the first detecting unit and configured to detect entrance of the original document, and   the controller starts, when the second detecting unit detects the entrance of the original document, control for stopping the original document in a position of the detection by the first detecting unit.   
     
     
         12 . The apparatus according to  claim 11 , wherein
 the driving unit includes:
 a pulse motor; and 
 a driver for the pulse motor, and 
   the controller stars, when the second detecting unit detects the entrance of the original document, counting of a number of pulses output to the driver and stops the original document in the position of the detection by the first detecting unit on the basis of a result of the counting.   
     
     
         13 . The apparatus according to  claim 10 , wherein the first detecting unit is a non-contact detecting unit. 
     
     
         14 . The apparatus according to  claim 13 , wherein
 the first detecting unit includes:
 an ultrasound generating unit configured to generate ultrasound; and 
 an ultrasound receiving unit configured to receive the ultrasound generated by the ultrasound generating unit, and 
   the ultrasound generating unit and the ultrasound receiving unit are opposed to each other across a conveying path for the original document.   
     
     
         15 . The apparatus according to  claim 14 , wherein the ultrasound generating unit is located further downstream in the conveying direction of the original document than the ultrasound receiving unit. 
     
     
         16 . The apparatus according to  claim 11 , wherein the second detecting unit is located below a conveying path for the original document. 
     
     
         17 . The apparatus according to  claim 10 , wherein
 the document conveying unit further includes a third roller configured to pick up the original document to the second roller, and   the second and third rollers are connected by a transmission mechanism.   
     
     
         18 . The apparatus according to  claim 17 , wherein the second roller is opposed to a fourth roller, the fourth roller inhibits double-feed of the original document picked up by the third roller. 
     
     
         19 . A method of detecting double-feed of a sheet comprising performing double-feed detection for the sheet in a state in which an end of the sheet on a downstream side in a conveying direction of the sheet is located further on an upstream side in the conveying direction of the sheet than a nip position of a roller configured to correct a tilt of the sheet. 
     
     
         20 . The method according to  claim 19 , wherein the double-feed detection is performed by a non-contact sensor.