PAPER FOLDING MACHINE

Abstract

A paper folding machine comprising folding mechanisms (11, 15, 24) arranged at folding positions (A-C) on a transport path (1), respectively, guides (8, 19, 20, 28, 29) positioning a paper sheet (F) relative to the folding positions by engagement with at least one side edge of the paper sheet, stoppers (12, 15, 25) stopping and positioning the paper sheet at the folding positions by bringing a leading edge of the paper sheet into contact with the stoppers, a fold misalignment detection unit (50) detecting a fold misalignment amount of the paper sheet for each folding position, and a controller (42) controlling positions of the guides and stoppers. The controller calculates, for each folding position, an average fold misalignment amount, and adjusts the position of the guide and/or stopper associated with the corresponding folding position so as to correct fold misalignment corresponding to the average fold misalignment amount.

Claims

1. A paper folding machine folding a printed paper sheet along at least one fold line preset on a printing surface of the paper sheet so as to form a signature, the paper folding machine comprising: a transport path for the paper sheet having an entrance, an exit and at least one folding position which is provided in an intermediate area of the transport path; at least one transport mechanism transporting the paper sheets one by one along the transport path between the entrance and a most upstream folding position, and between adjacent folding positions, and between a most downstream folding position and the exit; a folding mechanism arranged at each of the at least one folding position so as to fold the paper sheet along the associated fold line while the paper sheet is stopped at the associated folding position; at least one adjustable guide positioning the paper sheet relative to the at least one folding position by bringing at least one side of the paper sheet into contact with the at least one adjustable guide; an adjustable stopper arranged downstream of each of the at least one folding position so as to position and stop the paper sheet at the associated folding position by bringing a leading edge of the paper sheet into contact with the stopper; and a fold misalignment detection unit detecting, for each paper sheet and for each folding position, a fold misalignment amount, wherein the position of the at least one guide and/or the stopper associated with the corresponding folding position is adjusted based on detection data of the fold misalignment detection unit, characterized in that the paper folding machine further comprises: a drive mechanism capable of moving the at least one adjustable guide and the stopper; and a controller operatively connected to the drive mechanism, wherein the controller comprises a data receiving section receiving the detection data from the fold misalignment detection unit, a data counting section counting, for each folding position, the number of the detection data received by the data receiving section, a data storage section storing, for each folding position, the detection data received by the data receiving section, a statistical processing section calculating, for each folding position, an average fold misalignment amount using the detection data corresponding to a predetermined number of sample each time the number of detection data stored in the data storage section reaches, for each folding position, the number of sample, and an adjustment section adjusting the position of the at least one guide and/or the stopper associated with the corresponding folding position so as to correct fold misalignment corresponding to the average fold misalignment amount each time the average fold misalignment amount is calculated by the statistical processing section.

2. The paper folding machine according to claim 1, wherein the controller further comprises a misalignment tolerance storage section storing, for each folding position, the average fold misalignment amount as a misalignment tolerance, data stored in the misalignment tolerance storage section being updated each time the average fold misalignment amount is calculated by the statistical processing section, and a folding failure check section operatively connected to the at least one transport mechanism and the folding mechanism, and comparing the detection data with the misalignment tolerance each time the detection data is received by the data receiving section, and stopping the at least one transport mechanism and the folding mechanism when the detection data exceeds the misalignment tolerance.

3. The paper folding machine according to claim 1, wherein the paper folding machine further comprises a collection unit arranged downstream of the most downstream folding position on the transport path or at the exit of the transport path for collecting the paper sheet with folding failure, wherein the controller further comprises a misalignment tolerance storage section storing, for each folding position, the average fold misalignment amount as a misalignment tolerance, data stored in the misalignment tolerance storage section being updated each time the average fold misalignment amount is calculated by the statistical processing section, and a folding failure check section operatively connected to the collection unit, and comparing the detection data with the misalignment tolerance each time the detection data is received by the data receiving section, and collecting the corresponding paper sheet in the collection unit when the detection data exceeds the misalignment tolerance.

4. The paper folding machine according to claim 1, wherein the statistical processing section of the controller calculates, for each folding position, a standard deviation of the fold misalignment amount using the average fold misalignment amount and the detection data corresponding to the number of sample each time the number of the detection data stored in the data storage section reaches, for each folding position, the number of sample, and further calculates a variation judgement value of fold misalignment based on the standard deviation, wherein the controller further comprises a folding failure check section operatively connected to the at least one transport mechanism and the folding mechanism, and comparing the variation judgement value with a predetermined misalignment tolerance each time the variation judgement value is calculated by the statistical processing section, and stopping the at least one transport mechanism and the folding mechanism when the variation judgement value exceeds the misalignment tolerance.

5. The paper folding machine according to claim 1, wherein the paper folding machine further comprises a collection unit arranged downstream of the most downstream folding position on the transport path or at the exit of the transport path for collecting the paper sheet with folding failure, wherein the statistical processing section of the controller calculates, for each folding position, a standard deviation of the fold misalignment amount using the average fold misalignment amount and the detection data corresponding to the number of sample each time the number of the detection data stored in the data storage section reaches, for each folding position, the number of sample, and further calculates a variation judgement value of fold misalignment based on the standard deviation, wherein the controller further comprises a folding failure check section operatively connected to the collection unit, and comparing the variation judgement value with a predetermined misalignment tolerance each time the variation judgement value is calculated by the statistical processing section, and collecting the corresponding paper sheet in the collection unit when the variation judgement value exceeds the misalignment tolerance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 is a perspective view of a paper folding machine according to an embodiment of the present invention.

[0037] FIG. 2 is a plan view of the paper folding machine shown in FIG. 1.

[0038] FIG. 3 is a perspective view illustrating a detailed configuration near second and third folding positions of the paper folding machine shown in FIG. 1.

[0039] FIG. 4 is a block diagram illustrating a configuration of a fold misalignment detection unit of the paper folding machine shown in FIG. 1.

[0040] FIG. 5A is a block diagram illustrating a configuration of a controller of the paper folding machine shown in FIG. 1.

[0041] FIGS. 5B and 5C are block diagrams illustrating of modified examples of the controller shown in FIG. 5A.

[0042] FIG. 6A is a plan view of a paper sheet folded without fold misalignment by the paper folding machine shown in FIG. 1.

[0043] FIGS. 6B and 6C are plan views of paper sheets folded with fold misalignment by the paper folding machine shown in FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

[0044] A preferred embodiment of the present invention will be explained below with reference to accompanying drawings.

[0045] Generally, there are two types of fold misalignment of paper sheet which occur in a paper folding machine, that is, fold misalignment parallel with a fold line and fold misalignment oblique to the fold line. For simplicity of explanation, in the following, an embodiment in which only the fold misalignment parallel with the fold line occurs will be taken up.

[0046] FIG. 1 is a perspective view of a paper folding machine according to an embodiment of the present invention, and FIG. 2 is a plan view of the paper folding machine shown in FIG. 1. FIG. 3 is a perspective view illustrating a detailed configuration near second and third folding positions of the paper folding machine shown in FIG. 1.

[0047] Referring to FIG. 1 through FIG. 3, a paper folding machine according to the present invention comprises a transport path 1 for the paper sheet having an entrance 1a, an exit 1b. A first folding position (A), a second folding position (B) and a third folding position (C) are provided in an intermediate area of the transport path 1.

[0048] In this embodiment, the transport path 1 is composed of a first portion 1c almost straightly extending from the entrance 1a to the second folding position (B) through the first folding position (A), a second portion 1d extending from the second folding position (B) to the third folding position (C) in a direction perpendicular to the first portion 1c, and a third portion 1e straightly extending from the third folding position (C) to the exit 1b in a direction perpendicular to the second portion 1d.

[0049] In this embodiment, a paper feeding device 2 is connected to the entrance 1a of the transport path 1 so as to supply paper sheets P one by one to the paper folding machine of the present invention.

[0050] The paper feeding device 2 has a shelf 2a arranged for up-and-down movement and supporting a paper stack thereon, and a paper feed rotor 2b feeding the uppermost paper sheet P of the paper stack on the shelf 2a one by one.

[0051] In the present invention, the paper sheet P is printed in page order through imposition and folded along fold lines preset on its printing surface to form a signature.

[0052] Marks (M) for detection of fold misalignment are provided on sides of the paper sheet P which are mountain-folded along the fold lines, and extend across the related fold lines. The marks (M) are printed on a page margin outside the printing surface of the paper sheet when the paper sheet is printed.

[0053] The paper folding machine also comprises a first transport mechanism 3 transporting the paper sheets P one by one along the transport path 1 (the first portion 1c) from the entrance 1a to the first folding position (A), a second transport mechanism 4 transporting the paper sheets P one by one along the transport path 1 (the first portion 1c) from the first folding position (A) to the second folding position (B), a third transport mechanism 5 transporting the paper sheets P one by one along the transport path 1 (the second portion 1d) from the second folding position (B) to the third folding position (C) and a fourth transport mechanism 6 transporting the paper sheets P one by one along the transport path 1 (the third portion 1e) from the third folding portion (C) to the exit 1b.

[0054] The first transport mechanism 3 has a plurality of first conveyor belts 7 extending between the entrance 1a and the first folding position (A) on the transport path 1 (the first portion 1c).

[0055] A first guide (positioning ruler) 8 is arranged at a side of the transport path 1 (the first portion 1c) and extended parallel with the transport path 1 (the first portion 1c). The first guide 8 positions the paper sheet P relative to the first folding position (A) by engaging with a side edge of the paper sheet P transported by the first transport mechanism 3.

[0056] The first conveyor belt 7 adjacent to the first guide 8 of the plurality of the first conveyor belts 7 is inclined to gradually approach to the first guide 8 toward the downstream side, whereas the remaining first conveyor belt(s) 7 extend(s) parallel with the transport path 1 (the first portion 1c).

[0057] Thereby, the paper sheet P is transported by the first conveyor belts 7 while the side edge of the paper sheet P being aligned along the first guide 8.

[0058] The first guide 8 is slidably guided in a direction perpendicular to the transport path 1 (the first portion 1c). An intermediate portion of the first guide 8 is screwed onto a first screw shaft 10 which can be rotated around an axis thereof by a first motor 9. A position of the first guide 8 can be adjusted by forward and reverse rotation of the first motor 9.

[0059] A first folding mechanism 11 is arranged at the first folding position (A) for folding the paper sheet P in a direction perpendicular to the transport direction.

[0060] The first folding mechanism 11 has a buckle 11a and a set of rollers 11b-11d arranged at a bottom entrance of the buckle 11a.

[0061] The buckle 11a is provided with a first stopper 12. The first stopper 12 positions and stops the paper sheet P at the first folding position (A) by bringing a leading edge of the paper sheet P into contact with the first stopper 12 when the paper sheet P is inserted into the buckle 11a.

[0062] The first stopper 12 is attached to the buckle 11a so as to slide in a length direction of the buckle 11a, and attached to a first belt drive mechanism 13. Accordingly, a position of the first stopper 12 is adjustable in the length direction of the buckle 11a.

[0063] The first belt drive mechanism 13 is composed of a pair of horizontal pulley shafts 13a, 13b extending in a width direction of the buckle 11a, a pair of endless belts 13d, 13e extended between the pair of pulley shafts 13a, 13b through pulleys 13c, and a second motor 13f capable of rotating the pulley shaft 13a.

[0064] The first stopper 12 is fixed to the endless belts 13d, 13e and moved in the length direction of the buckle 11a by rotation of the endless belts 13d, 13e caused by drive of the second motor 13f.

[0065] The second transport mechanism 4 has a plurality of second conveyor belts 14 extended along the transport path 1 (the first portion 1c) between the first folding position (A) and the second folding position (B) on the transport path 1 and spaced from each other in a width direction of the transport path 1 (the first portion 1c).

[0066] A second folding mechanism 15 is arranged at the second folding position (B) so as to fold the paper sheet P in the transport direction.

[0067] The second folding mechanism 15 has a folding knife 15a arranged above the second folding position (B) for up-and-down movement and extending in the transport direction, a pair of first folding rollers 15b, 15c arranged beneath and opposite to the folding knife 15a and extended parallel to the folding knife 15a.

[0068] A second stopper 16 is arranged downstream of the second folding position (B) and extending at a right angle to the folding knife 15a (the transport direction) so as to stop and position the paper sheet P at the second folding position (B) by bring a leading edge of the paper sheet P into contact with the second stopper 16.

[0069] The second stopper 16 is slidably attached to a pair of slide guides 17a, 17b extending in the transport direction on both sides of the transport path 1 (the first portion 1c) and attached to a second belt drive mechanism 18. Accordingly, a position of the second stopper 16 is adjustable in the transport direction.

[0070] The second belt drive mechanism 18 is composed of a horizontal pulley shaft 18a arranged downstream of the second stopper 16 and extending at a right angle to the transport direction, pulleys 18b, 18c are attached to both ends of the pulley shaft 18a, pulleys 18d, 18e arranged upstream of and at a distance from the pulleys 18b, 19c, a pair of endless belts 18f, 18g extending between the pulleys 18b, 18c and the pulleys 18d, 18e, a third motor 18h, and an endless belt 18i extending between a pulley on a drive shaft of the third motor 18h and the pulley 18b.

[0071] Both ends of the second stopper 16 are attached to the endless belts 18f, 18g, and thereby, the position of the second stopper 16 can be adjusted by the endless belts 18f, 18g being rotated by the third motor 18h.

[0072] Second and third guides 19, 20 extend at a right angle to the second stopper 16 from the second stopper 16 to an upstream side of the transport path 1 (the first portion 1c), and are attached to the second stopper 16 so as to slide in a length direction of the second stopper 16.

[0073] The second and third guides 19, 20 position the paper sheet P relative to the second folding position (B) by engaging with side edges of the paper sheet P during transport of the paper sheet P.

[0074] Second screw shafts 21a, 21b each of which extends parallel to the second stopper 16 are attached to both ends of the second stopper 16 so as to be rotatable around axes thereof, and drive shafts of fourth motors 22a, 22b attached to the second stopper 16 are connected to outer ends of the second screw shafts 21a, 21b.

[0075] The second and third guides 19, 20 are screwed onto the second screw shafts 21a, 21b, and positions of the second and third guides 19, 20 can be adjusted by forward and reverse rotations of the fourth motors 22a, 22b.

[0076] The third transport mechanism 5 has a plurality of third conveyor belts 23 extended in the transport direction between the second and third folding positions (B), (C) on the transport path 1 (the second portion 1d) and spaced from each other in a direction perpendicular to the transport direction.

[0077] A third folding mechanism 24 is arranged at the third folding position (C) so as to fold the paper sheet P in the transport direction.

[0078] The third folding mechanism 24 has a folding knife 24a arranged above the third folding position (C) for up-and-down movement and extending in the transport direction, a pair of first folding rollers 24b, 24c arranged beneath and opposite to the folding knife 24a and extended parallel to the folding knife 24a.

[0079] A third stopper 25 is arranged downstream of the third folding position (C) and extending at a right angle to the folding knife 24a (the transport direction) so as to stop and position the paper sheet P at the third folding position (C) by bring a leading edge of the paper sheet P into contact with the third stopper 25.

[0080] The third stopper 25 is slidably attached to a pair of slide guides 26a, 26b extending in the transport direction on both sides of the transport path 1 (the second portion 1d) and attached to a third belt drive mechanism 27. Accordingly, a position of the third stopper 25 is adjustable in the transport direction.

[0081] The third belt drive mechanism 27 is composed of a horizontal pulley shaft 27a arranged downstream of the third stopper 25 and extending at a right angle to the transport direction, pulleys 27b, 27c are attached to both ends of the pulley shaft 27a, pulleys 27d, 27e arranged upstream of and at a distance from the pulleys 27b, 27c, a pair of endless belts 27f, 27g extending between the pulleys 27b, 27c and the pulleys 27d, 27e, a fourth motor 27h, and an endless belt 27i extending between a pulley on a drive shaft of the fourth motor 27h and the pulley 27b.

[0082] Both ends of the third stopper 25 are attached to the endless belts 27f, 27g, and thereby, the position of the third stopper 25 can be adjusted by the endless belts 27f, 27g being rotated by the fourth motor 27h.

[0083] Fourth and Fifth guides 28, 29 extend at a right angle to the third stopper 25 from the third stopper 25 to an upstream side of the transport path 1 (the second portion 1d), and are attached to the third stopper 25 so as to slide in a length direction of the third stopper 25.

[0084] The fourth and fifth guides 28, 29 position the paper sheet P relative to the third folding position (C) by engaging with side edges of the paper sheet P during transport of the paper sheet P.

[0085] Third screw shafts 30a, 30b each of which extends parallel to the third stopper 25 are attached to both ends of the third stopper 25 so as to be rotatable around axes thereof, and drive shafts of fifth motors 31a, 31b attached to the third stopper 25 are connected to outer ends of the third screw shafts 30a, 30b.

[0086] The fourth and fifth guides 28, 29 are screwed onto the third screw shafts 30a, 30b, and positions of the fourth and fifth guides 28, 29 can be adjusted by forward and reverse rotations of the fifth motors 31a, 31b.

[0087] The fourth transport mechanism 6 has a plurality of fourth conveyor belts 32 extended in the transport direction between the third folding position (C) and the exit 1b on the transport path 1 (the third portion 1e), and spaced from each other in a direction perpendicular to the transport direction.

[0088] Thus the paper sheet P supplied from the paper feeding device 2 to the first conveyor belts 7 (the first transport mechanism 3) is transported by the first transport mechanism 3 to the first folding position (A) along the transport path 1 (the first portion 1c). During the transport, the paper sheet P is positioned relative to the first folding position (A) by the first guide (positioning ruler) 8.

[0089] At the first folding position (A), the paper sheet P is inserted into the buckle 11a by a pair of the rollers lib, 11c, and stopped and positioned at the first folding position (A) by coming into contact with the first stopper 12 at the leading edge thereof. Next, a portion of the paper sheet P extending outward from the entrance of the buckle 11a is inserted between a pair of the rollers 11c, 11d so that the paper sheet P is folded in the direction perpendicular to the transport direction.

[0090] The folded sheet paper P falls on the second conveyor belts 14 (the second transport mechanism 5) and is transported by the second conveyor belts 14 to the second folding position (B).

[0091] The paper sheet P transported by the second conveyor belts 14 is stopped at the second folding position (B) by the second stopper 16 and positioned at the second folding position (B) by the second stopper 16 and the second and third guides 19, 20. Thereafter the folding knife 15a moves downward, and the paper sheet P is inserted between the pair of folding rollers 15b, 15c so as to be folded in the transport direction, and falls on the third conveyor belts 23 (the third transport mechanism 5) and is transported to the third folding position (C) by the third conveyor belts 23.

[0092] The paper sheet P transported by the third conveyor belts 23 is stopped at the third folding position (C) by t he third stopper 25 and positioned at the third folding position (C) by the third stopper 25 and the fourth and fifth guides 28, 29. Thereafter the folding knife 24a moves downward, and the paper sheet P is inserted between the pair of folding rollers 24b, 24c so as to be folded in the transport direction, and falls on the fourth conveyor belts 32 (the fourth transport mechanism 6) and is discharged from the exit 1b of the transport path 1 by the fourth conveyor belts 32.

[0093] The paper folding machine of the present invention further comprises a fold misalignment detection unit 50 detecting, for each paper sheet P and for each folding position (A)-(C), a fold misalignment amount.

[0094] FIG. 4 is a block diagram illustrating a configuration of the fold misalignment detection unit 50.

[0095] Referring to FIGS. 4 and 3, the fold misalignment detection unit 50 comprises a first sensor 33 attached to the second stopper 16 of the second folding mechanism 15 so as to detect when the paper sheet P stops at the second folding position (B), first cameras 34 attached to the second stopper 16 so as to shoot the marks (M) associated with the first folding position (A) of the paper sheet P stopped at the second folding position (B), a second sensor 35 attached to the third stopper 25 of the third folding mechanism 24 so as to detect when the paper sheet P stops at the third folding position (C), second cameras 36 attached to the third stopper 25 so as to shoot the marks (M) associated with the second folding position (B) of the paper sheet P stopped at the third folding position (C).

[0096] The first cameras 34 perform shooting operation each time a detection signal is outputted form the first sensor 33, and the second cameras 36 perform shooting operation each time a detection signal is outputted from the second sensor 35.

[0097] The fold misalignment detection unit 50 also comprises a third sensor 37 arranged downstream of the third folding position (C) and above the transport path 1 (the third portion 1e) so as to detect passage of a leading edge of the paper sheet P and third cameras 38 arranged side by side with the third sensor 37 in a width direction of the transport path 1 (the third portion 1e) so as to shoot the marks (M) associated with the third folding position (C) of the paper sheet P.

[0098] The third cameras 38 perform shooting operation each time a detection signal is outputted from the third sensor 37.

[0099] The fold misalignment detection unit 50 further comprises a reference value storage section 39 storing as a reference value a value of area of the mark (M) in each of the images obtained by the first through third cameras 34, 36, 38 when the paper sheet P is folded without fold misalignment, and an image processing section 40 processing each of the images of the paper sheet P shot by the first through third cameras 34, 36, 38 so as to calculate an area of the mark (M) in each of the images of the paper sheet P.

[0100] In this case, the area calculation by the image processing unit 40 can be executed by a known appropriate image processing method. In this embodiment, for example, the mark (M) is separated as a blob from a background in the image using binarization processing and blob processing and then a value of area of the blob is measured.

[0101] The fold misalignment detection unit 50 further comprises a detection section 41 calculating a difference between the value of area calculated by the image processing section 40 and the corresponding reference value so as to detect a fold misalignment amount each time the value of area of the mark (M) is calculated by the image processing section 40, and outputting the detected fold misalignment amount.

[0102] A method of detection of the fold misalignment amount by the detection section 41 will be specifically explained with reference to the drawings.

[0103] FIG. 6A is a plan view of a paper sheet P0 folded without fold misalignment by the first folding mechanism 11. FIGS. 6B and 6C are plan views of paper sheets P1, P2 folded with fold misalignment by the first folding mechanism 11.

[0104] Marks M0-M2 shown in FIGS. 6A-6C are shot by the first cameras 34 when the paper sheets P0-P2 stop at the second folding position (B), respectively.

[0105] Referring to FIG. 6A, in the reference value storage section 39, a value of the mark (M0) in each of the images of the paper sheet P0 shot by the first cameras 34 is stored as the reference value in advance.

[0106] When the paper sheet P1 shown in FIG. 6B stops at the second folding position (B) and is shot by the first cameras 34, a value of area of the mark (M1) in each of images of the paper sheet P1 is outputted from the image processing section 40. Then the detection section 41 subtracts the corresponding reference value from the value of area of the mark (M1), divides the subtraction value by a width of the corresponding mark (M0), and outputs the division value as a fold misalignment amount.

[0107] In this example, the fold misalignment amount is a positive value because the value of area of the mark (M1) is larger than the reference value. The positive fold misalignment amount indicates that the actual fold line is shifted downstream from the set fold line.

[0108] Also, when the paper sheet P2 stops at the second folding position (B) and is shot by the first cameras 34, a value of area of the mark (M2) in each of images of the paper sheet P2 is outputted from the image processing section 40. Then the detection section 41 subtracts the corresponding reference value from the value of area of the mark (M2), divides the subtraction value by a width of the corresponding mark (M0), and outputs the division value as a fold misalignment amount.

[0109] In this example, the fold misalignment amount is a negative value because the value of area of the mark (M2) is smaller than the reference value. The negative fold misalignment amount indicates that the actual fold line is shifted upstream from the set fold line.

[0110] The paper folding machine of the present invention further comprises a controller 42 operatively connected to the first motor 9 (a drive mechanism of the first guide 8), the first belt drive mechanism 13 (a drive mechanism of the first stopper 12), the second belt drive mechanism 18 (a drive mechanism of the second stopper 16), a drive mechanism of the fourth motors 22a, 22b (the second and third guides 19, 20), the third belt drive mechanism 27 (a drive mechanism of the third stopper 25), and the fifth motors 31a, 31b (a drive mechanism of the fourth and fifth guides 28, 29).

[0111] FIG. 5A is a block diagram illustrating a configuration of the controller 42.

[0112] The controller 42 is a programmed computer, and comprises a data receiving section 43 receiving detection data from the fold misalignment detection unit 50, a data counting section 44, for each folding position (A)-(C), the number of the detection data received by the data receiving section 43, and a data storage section 45 storing, for each folding position (A)-(C), the detection data received by the data receiving section 43.

[0113] The controller 42 also comprises a statistical processing section 46 calculating, for each folding position (A)-(C), an average fold misalignment amount using the detection data corresponding to a predetermined number of sample each time the number of detection data stored in the data storage section 45 reaches, for each folding position, the number of sample.

[0114] That is to say, assuming that the predetermined number of sample is n and the detection data are 1, 2, 3, . . . , n for each folding position (A)-(C), the statistical processing section 46 calculates, for each folding position (A)-(C), the average fold misalignment amount according to

[00001]$\begin{array}{cc}\stackrel{\_}{}=\frac{1}{n}.Math.\underset{i=1}{\overset{n}{.Math.}}.Math.{}_i& \left(1\right)\end{array}$

and outputs the calculated average fold misalignment amount.

[0115] In this case, the predetermined number of sample may be stored as a default value in a memory of the controller 42 in advance, or an appropriate number of sample may be inputted to the controller 42 through an input section which is provided on the controller 42 so as to receive an input of the number of sample.

[0116] The controller 42 further comprises an adjustment section 47 adjusting the position of the guide 8, 19, 20, 28, 29 and/or the stopper 12, 16, 25 associated with the corresponding folding position so as to correct fold misalignment corresponding to the average fold misalignment amount each time the average fold misalignment amount is calculated by the statistical processing section 46.

[0117] Thus, according to the present invention, the fold misalignment amount of the paper sheet P is automatically detected for each folding position (A)-(C) during operation of the paper folding machine, and, for each folding position (A)-(C), each time the obtained detection data reaches the predetermined number of sample, the average fold misalignment amount is calculated and the corresponding stopper 12, 16, 25 and/or guide 8, 19, 20, 28, 29 are(is) automatically adjusted using the calculated average fold misalignment amount. Accordingly, the amount of work for workers is greatly reduced and the work does not require skill, and thereby, productivity is dramatically improved and significant cost reductions can be achieved.

[0118] Furthermore, according to the present invention, the adjustment of the paper folding machine is carried out in a manner such that the fold misalignment amounts are statistically minimized while considering the fold misalignment amount within the allowable range as well as the fold misalignment amount exceeding the allowable range. Consequently, the adjustment accuracy is improved so that the incidence of defective products is further reduced.

[0119] FIG. 5B is a block diagram illustrating a modified example of the controller 42 shown in FIG. 5A.

[0120] In the example shown in FIG. 5B, a controller 42 comprises a misalignment tolerance storage section 48 storing, for each folding position (A)-(C), the average fold misalignment amount as a misalignment tolerance in addition to the configuration shown in FIG. 5A. In this case, data stored in the misalignment tolerance storage section 48 are updated each time the average fold misalignment amount is calculated by the statistical processing section 46.

[0121] In this example, the controller 42 also comprises a folding failure check section 49 operatively connected to the first through fourth transport mechanisms 3-6 and the first through third folding mechanisms 11, 15, 24, and comparing the detection data with the misalignment tolerance each time the detection data is received by the data receiving section 43, and stopping the first through fourth transport mechanisms 3-6 and the first through third folding mechanisms 11, 15, 24 when the detection data exceeds the misalignment tolerance.

[0122] According to the modified example shown in FIG. 5B, not only the adjustment for fold misalignment of the paper folding machine but also the check of folding failure (defective product) is automatically performed.

[0123] Although, in the modified example shown in FIG. 5B, the paper folding machine stops when the folding failure (defective product) is detected, according to another modified example, the paper folding machine not stops but discharges a defective product automatically when the folding failure (defective product) is detected.

[0124] In this case, the paper folding machine further comprises a collection unit arranged downstream of the third folding position (C) on the transport path 1 (the third portion 1e) or at the exit 1b of the transport path 1 for collecting the paper sheet with folding failure. Then the folding failure check section 49 is operatively connected to the collection unit and compares the detection data with the misalignment tolerance each time the detection data is received by the data receiving section 43, and collecting the corresponding paper sheet P in the collection unit when the detection data exceeds the misalignment tolerance.

[0125] FIG. 5C is a block diagram illustrating another modified example of the controller 42 shown in FIG. 5A.

[0126] In the modified example shown in FIG. 5C, not only a controller 42 has the configuration shown in FIG. 5A, but also a statistical processing section 46 further calculates, for each folding position (A)-(C), a standard deviation of the fold misalignment amount using the average fold misalignment amount and the detection data corresponding to the number of sample each time the number of the detection data stored in the data storage section 45 reaches, for each folding position, the number of sample, and calculates a variation judgement value of fold misalignment based on the standard deviation.

[0127] That is to say, assuming that the predetermined number of sample is n and the detection data are 1, 2, 3, . . . , n for each folding position (A)-(C), the statistical processing section 46 calculates, for each folding position (A)-(C), the standard deviation u according to

[00002]$\begin{array}{cc}=\sqrt{\frac{1}{n}.Math.\underset{i=1}{\overset{n}{.Math.}}.Math.{\left({}_i-\stackrel{\_}{}\right)}^2}& \left(2\right)\end{array}$

[0128] where is the average fold misalignment amount defined by the equation (1).

and then calculates the variation judgement value of fold misalignment based on the standard deviation u according to a predetermined equation, for example,

=m(m=1 or 2 or 3)(3)

[0129] The controller 42 also comprises a folding failure check section 49 operatively connected to the first through fourth transport mechanisms 3-6 and the first through third folding mechanisms 11, 15, 24, and comparing the variation judgement value with a predetermined misalignment tolerance each time the variation judgement value is calculated by the statistical processing section 46, and stopping the first through fourth transport mechanisms 3-6 and the first through third folding mechanisms 11, 15, 24 when the variation judgement value exceeds the predetermined misalignment tolerance.

[0130] In this case, the predetermined misalignment tolerance may be stored as a default value in a memory of the controller 42 in advance, or an appropriate misalignment tolerance may be inputted to the controller 42 through an input section which is provided on the controller 42 so as to receive an input of the misalignment tolerance.

[0131] According to the modified example shown in FIG. 5C, not only the adjustment for fold misalignment of the paper folding machine but also the check of folding failure (defective product) is automatically performed.

[0132] Although, in the modified example shown in FIG. 5C, the paper folding machine stops when the folding failure (defective product) is detected, according to another modified example, the paper folding machine not stops but discharges a defective product automatically when the folding failure (defective product) is detected.

[0133] In this case, the paper folding machine further comprises a collection unit arranged downstream of the third folding position (C) on the transport path 1 (the third portion 1e) or at the exit 1b of the transport path 1 for collecting the paper sheet with folding failure. Then the folding failure check section 49 is operatively connected to the collection unit and compares the variation judgement value with the predetermined misalignment tolerance each time the variation judgement value is calculated by the statistical processing section 46, and collecting the corresponding paper sheet P in the collection unit when the variation judgement value exceeds the predetermined misalignment tolerance.

[0134] Although the preferred embodiment of the present invention has been set forth for purposes of illustration, the foregoing description should not be deemed a limitation of the invention herein. Accordingly, various modifications, adaptations and alternatives may occur to one skilled in the art without departing from the spirit and the scope of the present invention.

[0135] For example, although, for simplicity of explanation, the above embodiment is limited to the case where the fold misalignment is parallel to a fold line, the present invention can be applied to not only the case where the fold misalignment is parallel to the fold line but also the case where the fold misalignment is oblique to the fold line.

[0136] When both the fold misalignment parallel to the fold line and the fold misalignment oblique to the fold line arise, not only the first through fifth guides 8, 19, 20, 28, 29 can be moved in the direction perpendicular to the transport direction like the above embodiment but also the inclination angle of those guides 8, 19, 20, 28, 29 with respect to the transport path can be adjusted. In addition, not only the first through third stoppers 12, 16, 25 can be moved in the transport direction like the above embodiment, but also the inclination angle of those stoppers 12, 16, 25 can be adjusted.

[0137] For example, although, in the above embodiment, the paper folding machine has three folding positions (A)-(C), and a buckle-type folding machine is arranged at the first folding position (A), and a knife-type folding machine is arranged at the second folding position (B), a knife-type folding machine is arranged at the third folding position (C), the paper folding machine may have any number of folding positions, and any suitable type of folding machine may be arranged.

DESCRIPTION OF REFERENCE NUMERALS

[0138] 1 Transport path [0139] 1a Entrance [0140] 1b Exit [0141] 1c First portion [0142] 1d Second portion [0143] 1e Third portion [0144] 2 Paper feeding device [0145] 2a Shelf [0146] 2b Paper feed rotor [0147] 3 First transport mechanism [0148] 4 Second transport mechanism [0149] 5 Third transport mechanism [0150] 6 Fourth transport mechanism [0151] 7 First conveyor belt [0152] 8 First guide (positioning ruler) [0153] 9 First motor [0154] 10 First screw shaft [0155] 11 First folding mechanism [0156] 11a Buckle [0157] 11b-11d Roller [0158] 12 First stopper [0159] 13 First belt drive mechanism [0160] 13a, 13b Pulley shaft [0161] 13c Pulley [0162] 13d, 13e Endless belt [0163] 13f Second motor [0164] 14 Second conveyor belt [0165] 15 Second folding mechanism [0166] 15a Folding knife [0167] 15b, 15c Folding roller [0168] 16 Second stopper [0169] 17a, 17b Slide guide [0170] 18 Second belt drive mechanism [0171] 18a Pulley shaft [0172] 18b-18e Pulley [0173] 18f, 18g Endless belt [0174] 18h Third motor [0175] 18i Endless belt [0176] 19 Second guide [0177] 20 Third guide [0178] 21a, 21b Second screw shaft [0179] 22a, 22b Fourth motor [0180] 23 Third conveyor belt [0181] 24 Third folding mechanism [0182] 24a Folding knife [0183] 24b, 24c Folding roller [0184] 25 Third stopper [0185] 26a, 26b Slide guide [0186] 27 Third belt drive mechanism [0187] 27a Pulley shaft [0188] 27b-27e Pulley [0189] 27f, 27g Endless belt [0190] 27h Fourth motor [0191] 27i Endless belt [0192] 28 Fourth guide [0193] 29 Fifth guide [0194] 30a, 30b Third screw shaft [0195] 31a, 31b Fifth motor [0196] 32 Fourth conveyor belt [0197] 33 First sensor [0198] 34 First camera [0199] 35 Second sensor [0200] 36 Second camera [0201] 37 Third sensor [0202] 38 Third camera [0203] 39 Reference value storage section [0204] 40 Image processing section [0205] 41 Detection section [0206] 42, 42, 42 Controller [0207] 43 Data receiving section [0208] 44 Data counting section [0209] 45 Data storage section [0210] 46, 46 Statistical processing section [0211] 47 Adjustment section [0212] 48 Misalignment tolerance storage section [0213] 49, 49 Folding failure check section [0214] 50 Fold misalignment detection unit [0215] A First folding position [0216] B Second folding position [0217] C Third folding position [0218] M, M0, M1, M2 Mark [0219] P, P0, P1, P2 Paper sheet