Sheet abnormality detection apparatus and method

Abstract

A sheet abnormality detection apparatus includes a plurality of abutting members which move upon coming into contact with at least one of sheets conveyed to overlap while being shifted from each other in a convey direction and an object attached to a sheet. The plurality of abutting members are disposed side by side in a direction perpendicular to a sheet convey direction. The apparatus also includes an abnormality detection unit which detects a sheet abnormality on the basis of a relative positional shift among the plurality of abutting members. A sheet abnormality detection method is also disclosed.

1 . A sheet abnormality detection apparatus comprising:
 a plurality of abutting members which move upon coming into contact with at least one of sheets conveyed to overlap while being shifted from each other in a convey direction and an object attached to a sheet, said plurality of abutting members being disposed side by side in a direction perpendicular to a sheet convey direction; and   abnormality detection means for detecting a sheet abnormality on the basis of any relative positional shift among said plurality of abutting members.   
     
     
         2 . An apparatus according to  claim 1 , wherein said abnormality detection means comprises a photoelectric sensor. 
     
     
         3 . An apparatus according to  claim 2 , further comprising
 a first lever which supports a first abutting member as one of said plurality of abutting members and moves interlocked with said first abutting member, and   a second lever which supports a second abutting member as another one of said plurality of abutting members and adjacent to said first abutting member and moves interlocked with said second abutting member,   wherein said photoelectric sensor detects a relative positional shift between said first lever and said second lever.   
     
     
         4 . An apparatus according to  claim 3 , wherein said photoelectric sensor comprises
 a light-projecting unit provided to one of said first lever and said second lever, and   a light-receiving unit provided to the other one of said first lever and said second lever.   
     
     
         5 . An apparatus according to  claim 2 , further comprising light reception amount changing means provided to one side of a first abutting member and a second abutting member as two ones of said plurality of abutting members,
 wherein said photoelectric sensor is provided to the other side of said first abutting member and said second abutting member, and   said light reception amount changing means changes a light reception amount of said photoelectric sensor in accordance with a relative positional shift between said first abutting member and said second abutting member.   
     
     
         6 . An apparatus according to  claim 5 , wherein said photoelectric sensor comprises
 a light-projecting unit provided to one end side of said light reception amount changing means, and   a light-receiving unit provided to the other end side of said light reception amount changing means.   
     
     
         7 . An apparatus according to  claim 6 , further comprising
 a first eccentric shaft which is pivotally supported and rotatably supports said first abutting member, said first eccentric shaft being eccentric from a rotation center of said first abutting member, and   a second eccentric shaft which is pivotally supported and rotatably supports said second abutting member, said second eccentric shaft being eccentric from a rotation center of said second abutting member,   wherein said light reception amount changing means is provided to one side of said first eccentric shaft and said second eccentric shaft, and   said photoelectric sensor is provided to the other side of said first eccentric shaft and said second eccentric shaft.   
     
     
         8 . An apparatus according to  claim 2 , further comprising a through hole formed in one side of a first abutting member and a second abutting member as two adjacent ones of said plurality of abutting members,
 wherein said photoelectric sensor is provided to the other side of said first abutting member and said second abutting member, and   said photoelectric sensor receives light passing through said through hole, and a light reception amount of said photoelectric sensor changes in accordance with a positional shift between said through hole and said photoelectric sensor which accompanies a relative positional shift between said first abutting member and said second abutting member.   
     
     
         9 . An apparatus according to  claim 8 , further comprising
 a first eccentric shaft which is pivotally supported and rotatably supports said first abutting member, said first eccentric shaft being eccentric from a rotation center of said first abutting member, and   a second eccentric shaft which is pivotally supported and rotatably supports said second abutting member, said second eccentric shaft being eccentric from a rotation center of said second abutting member,   wherein through hole is formed in one side of said first eccentric shaft and said second eccentric shaft, and   said photoelectric sensor is provided to the other side of said first eccentric shaft and said second eccentric shaft.   
     
     
         10 . An apparatus according to  claim 1 , wherein said abnormality detection means comprises a first press detection sensor which is provided to one side of a first abutting member and a second abutting member as two ones of said plurality of abutting members and detects a press state against one of the other one and the other side of said first abutting member and said second abutting member. 
     
     
         11 . An apparatus according to  claim 10 , wherein said abnormality detection means further comprises a second press detection sensor which is provided to the other side of said first abutting member and said second abutting member and detects a press state against one of one and one side of said first abutting member and said second abutting member. 
     
     
         12 . An apparatus according to  claim 10 , wherein said first press detection sensor comprises a detection switch comprising a detection element which is movably supported and abuts against one of the other one and the other side of said first abutting member and said second abutting member, and a detector which detects that said detection element has moved for a predetermined amount. 
     
     
         13 . An apparatus according to  claim 10 , wherein said first press detection sensor comprises a sensor-attached ball plunger. 
     
     
         14 . An apparatus according to  claim 13 , further comprising one of a recess and a hole which is formed on the other side of said first abutting member and said second abutting member and which faces a distal end of said sensor-attached ball plunger,
 wherein said sensor-attached ball plunger detects that said distal end thereof has disengaged from one of said recess and said hole from a relative positional displacement between said first abutting member and said second abutting member.   
     
     
         15 . An apparatus according to  claim 10 , wherein said first press detection sensor comprises a pressure sensor which detects a press force applied by one of one and one side of said first abutting member and said second abutting member. 
     
     
         16 . An apparatus according to  claim 1 , wherein said abnormality detection means comprises a proximity sensor which detects proximity with one of one and one side of a first abutting member and a second abutting member as two ones of said plurality of abutting members. 
     
     
         17 . An apparatus according to  claim 1 , wherein said abnormality detection means comprises distance detection means for detecting a distance with respect to one of one and one side of a first abutting member and a second abutting member as two ones of said plurality of abutting members. 
     
     
         18 . An apparatus according to  claim 1 , further comprising overlap feed detection means for detecting that at least one of a first abutting member and a second abutting member as two ones of said plurality of abutting members has moved for not less than a predetermined amount. 
     
     
         19 . An apparatus according to  claim 18 , wherein said overlap feed detection means comprises
 a detection target body which moves as one of said first abutting member and said second abutting member moves, and   an overlap feed detector which detects that said detection target body has moved for not less than a predetermined amount.   
     
     
         20 . An apparatus according to  claim 19 , further comprising adjusting means for adjusting positions of said overlap feed detector and said detection target body relative to each other. 
     
     
         21 . An apparatus according to  claim 1 , further comprising
 a first eccentric shaft which is pivotally supported and rotatably supports a first abutting member as one of said plurality of abutting means, said first eccentric shaft being eccentric from a rotation center of said first abutting member, and   a second eccentric shaft which is pivotally supported and rotatably supports a second abutting member as another one of said plurality of abutting member, said second eccentric shaft being eccentric from a rotation center of said second abutting member,   wherein said abnormality detection means detects a relative positional shift between said first eccentric shaft and said second eccentric shaft.   
     
     
         22 . An apparatus according to  claim 1 , further comprising
 a first detecting portion comprising said plurality of abutting members, and   a second detecting portion comprising other plurality of abutting members having the same function as that of said plurality of abutting members, said second detecting portion being spaced apart from said first detecting portion in the sheet convey direction, said other plurality of abutting members being disposed side by side in a direction perpendicular to the sheet convey direction, and gaps among adjacent abutting members of said second detecting portion not overlapping gaps among adjacent abutting members of said first detecting portion when seen in the sheet convey direction.   
     
     
         23 . An apparatus according to  claim 22 ,
 wherein said abnormality detection means comprises a plurality of sensors which detect a relative positional shift between said adjacent abutting members of each of said first detecting portion and said second detecting portion, and   said apparatus further comprises a controller which selects a sensor to be used for sheet abnormality detection among said plurality of sensors in accordance with a sheet size.   
     
     
         24 . An apparatus according to  claim 1 , wherein said abnormality detection means comprises
 a plurality of abutting member position detection means for detecting positions of said plurality of abutting members, respectively, and   operational means for comparing an output from at least one abutting member position detection means with an output from another abutting member position detection means among outputs from said plurality of abutting member position detection means and detects a sheet abnormality on the basis of a comparison result.   
     
     
         25 . An apparatus according to  claim 24 , wherein said operational means comprises
 subtracting means for obtaining a difference between the output from said at least one abutting member position detection means and the output from said other abutting member position detection means, and   judging means for comparing an absolute value of a difference obtained by said subtracting means with a preset allowance, and determining a sheet abnormality when the absolute value of the difference is larger than the allowance.   
     
     
         26 . An apparatus according to  claim 24 , wherein said operational means comprises double-feed detection means for comparing the output from at least one abutting member position detection means among the outputs from said plurality of abutting member position detection means with a preset reference value, and detecting a double sheet feed on the basis of a comparison result. 
     
     
         27 . An apparatus according to  claim 24 , wherein said plurality of abutting members and said abnormality detection means are provided upstream of a feeder board in the sheet convey direction, said feeder board is included in sheet convey means for conveying a sheet fed from a feed device to printing means, and said feed device comprises a suction device which feeds out stacked sheets one by one to overlap to be shifted from each other in the convey direction. 
     
     
         28 . An apparatus according to  claim 1 , wherein said abutting members are moved in a direction perpendicular to a sheet surface by at least one of a sheet that passes said abutting members and an object attached to the sheet. 
     
     
         29 . A sheet abnormality detection method comprising the steps of:
 conveying sheets to overlap while being shifted from each other in a convey direction;   detecting positions of a plurality of abutting members which move upon coming into contact with at least one of a sheet and an object attached to a sheet, the plurality of abutting members being disposed side by side in a direction perpendicular to a sheet convey direction, and   comparing a position of at least one abutting member with a position of another abutting member among the plurality of abutting members and detecting a sheet abnormality on the basis of a comparison result.   
     
     
         30 . A method according to  claim 29 , wherein the step of detecting positions comprises the steps of
 obtaining a difference between information on a position of at least one abutting member and information on a position of said other abutting member, and   comparing an absolute value of the difference with a preset allowance and determining a sheet abnormality when the absolute value of the difference is larger than the allowance.   
     
     
         31 . A method according to  claim 29 , further comprising the step of comparing a position of at least one abutting member among the plurality of abutting members with a preset reference value and detecting a sheet double feed on the basis of a comparison result. 
     
     
         32 . A method according to  claim 29 , wherein the step of conveying further comprises the steps of
 feeding stacked sheets one by one by a suction device onto a feeder board to overlap while being shifted from each other in the convey direction, and   feeding the sheets from the feeder board to printing means,   wherein the step of detecting positions and the step of detecting an abnormality are performed while the sheet is fed to the feeder board by the suction device.