US3831927A

US3831927A - Method and apparatus for folding sheets such as drawings

Info

Publication number: US3831927A
Application number: US00348883A
Authority: US
Inventors: Herten J Van
Original assignee: Oce Van der Grinten NV
Current assignee: Canon Production Printing Holding BV
Priority date: 1970-04-24
Filing date: 1973-04-09
Publication date: 1974-08-27
Anticipated expiration: 1991-08-27

Abstract

Large sheets such as drawings having any of various lengths are folded into packets of standard length in the direction transverse to the folds by feeding the sheets individually past length measuring points spaced apart along a pathway to a zigzag folder which is actuated at intervals determined by a computing control system in response to signals received from sheet detectors located at the measuring points. The detectors sense simultaneously a certain location of the leading edge of each sheet and the presence or absense of the sheet at other points in the pathway, thus determining the folding pattern to be applied to the sheet; and as the sheet is advanced the control system measures the residual length, if any exists, by which the sheet trails a point where its presence was sensed and determines correspondingly the locations of certain folds. When a sheet is longer than the length ranges defined between the detectors, its leading part is folded into panels having the desired packet length until the trailing edge has been brought into a range between two detectors, whereupon the residual length and corresponding fold location(s) are determined.

Description

United States Patent 1191 Van Herten [4 Aug. 27, 1974 METHOD AND APPARATUS FOR FOLDING SHEETS SUCH AS DRAWINGS [75] Inventor: Jozef Marie Van Herten, Venlo,

Netherlands [73] Assignee: Oce-Van der Grinten N.V., Venlo,

Netherlands [22] Filed: Apr. 9, 1973 [21] Appl. No.: 348,883

Related US. Application Data [63] Continuation-in-part of Ser. No 137,549, April 26,

1971, abandoned.

[] Foreign Application Priority Data Apr. 10, 1972 Netherlands 7204777 [52] US. Cl. 270/79 [51] Int. Cl Bh 45/20 [58] Field of Search 270/79, 61, 67, 69, 80,

[56] References Cited UNITED STATES PATENTS 2,374,779 5/1945 Preston 3,154,726 10/1964 McClain 270/81 X 3,322,961 5/1967 Harrison et a1. 270/83 UX 3,467,370 9/1969 Grantham 270/85 3,485,492 12/1969 lltis 270/84 3,589,709 6/1971 Hey et a1. 270/83 FOREIGN PATENTS OR APPLICATIONS 1,276,660 9/1968 Germany shecf Leng h 1,436,588 3/1969 Germany Primary Examiner-Wm H. Grieb Attorney, Agent, or Firm-Albert 'C. Johnston 7] ABSTRACT Large sheets such as drawings having any of various lengths are folded into packets of standard length in the direction transverse to the folds by feeding the sheets individually past length measuring points spaced apart along a pathway to a zigzag folder which is actuated at intervals determined by a computing control system in response to signals received from sheet detectors located at the measuring points. The detectors sense simultaneously a certain location of the leading edge of each sheet and the presence or absense of the sheet at other points in the pathway, thus determining the folding pattern to be applied to the sheet; and as the sheet is advanced the control system measures the residual length, if any exists, by which the sheet trails a point where its presence was sensed and determines correspondingly the locations of certain folds. When a sheet is longer than the length ranges defined between the detectors, its leading part is folded into panels having the desired packet length until the trailing edge has been brought into a range between two detectors, whereupon the residual length and corresponding fold location(s) are determined.

20 Claims, 7 Drawing Figures FOLDING PLAN I1: L ngth PAIENTED M182 7 014 3,831 .827 sum 3 or 5 Fig.2

FOLDING -A I Fowme PLAN E 50 100 150 200210 unfit 0 20 50 100 1 200 210 PAIENEmuczmu sumsurs van mom Nam Eu can on. U|

METHOD AND APPARATUS FOR FOLDING SHEETS SUCH AS DRAWINGS This application is a continuation-in-part of copending US Pat. application Ser. No. 137,549 filed Apr. 26, 1971, now abandoned the disclosure of which is hereby incorporated hereinto by reference.

This invention relates to a method and apparatus for folding large sheets such as engineering drawings, photoprints thereof and other sheets commonly referred to as drawings.

In many countries the manner of folding standard sheet sizes has been standardized in respect of the folding program, i.e., the pattern and the location of folds, so that a larger standard size is reduced by folding to a small standard size, e.g. A4.

The folding of sheets is usually time consuming. For example, in the photographic printing of large drawings, the time needed for folding may be a multiple of the time required for printing. Automatic folding devices are known, but they are expensive and do not always function satisfactorily, particularly when nonstandard sizes are to be folded. Sometimes the apparatus can be adjusted for obtaining any desired division of the folds, but this is a difficult and time-consuming practice. Non-standard sizes are usually folded like a standard size, after which the upper or lower flap is refolded, for example by hand, to prevent it from protruding too far. Alternatively, this upper or lower flap remains shorter than with a standard size.

An object of the present invention is to improve this situation, and to provide a way of quickly and inexpensively folding sheets, including non-standard size sheets, according to a logical folding program and so that each folded sheet will have a nice appearance and be free from too long or too short flaps.

According to the invention, as each sheet is being fed to a folding device suitable for folding it at intervals in zig-zig manner, the length of the sheet in the direction perpendicular to the folds to be made in it is sensed so as to classify the sheet into the appropriate one of a plurality of successive length ranges, each of which corresponds to a preset folding pattern, and thus the folding pattern to be used for the sheet is determined; then the amount if any by which the length of the sheet exceeds a length reaching to the lower limit of one of the length ranges is determined, which excess is referred to herein as the residual length"; and the sheet then is folded according to the folding pattern and at locations derived from the determinations of its length range and its residual length.

The folding pattern to be used can be derived immediately and unmistakably from that one of the predetermined length ranges into which the length of the sheet to be folded falls, and the exact location(s) required for one or more of the folds is determined by the measurement of the residual length. This is much simpler than determining the total length and then considering all possibilities of folding patterns and fold locations until the desired folding program has been found. Moreover, for larger sizes it is possible in this way to predetermine the location of a first fold, for example, that of the fold next adjacent to an edge of the folded sheet having a protruding attachment portion, and even to start the folding operation, prior to deriving the locations of further folds from the residual length measurement. Thus, according to the invention, the classification of the sheet length can be performed when the leading edge of the sheet is in close proximity to the entrance of a folding device, whereas the residual length can be measured after the first folding operation has already been started, e.g., by moving the sheet further into and through the folding device.

In an advantageous practice of the invention for folding sheets in which more than two folds are to be provided and the residual length varies, the lengths of the respective portions (flaps or panels) of the sheets between their trailing edges and the fold next adjacent thereto are kept constant. Similarly, for sheets of varying residual length and in which more than four folds are to be provided, the lengths of the respective portions (panels) between both the leading and the trailing edges of the sheet and the respective folds next adjacent (opposite) to those edges are advantageously kept constant.

Furthermore, for sheets in at least some of the length ranges, when their respective residual lengths vary, the locations of two superimposed folds in the respective folded sheets may be varied together to the same extent.

The method is preferably carried out in such a way that the folding patterns used for sheets in the dimensional ranges which encompass standard sheet sizes correspond with the folding patterns standardized for those sizes.

Further according to the invention, an apparatus is provided for effectively carrying out the described method. This apparatus comprises in association with a pathway, or track, along which the sheets to be folded are transported to a folding device; means for detecting the presence of the leading edge of a sheet approaching the folding device; means for then determining the length range into which the sheet falls by sensing the presence or absence of the sheet at detecting elements spaced apart at locations in the pathway behind the location of the detector of the leading edge of the sheet; means for determining the residual length of the sheet by measuring the portion of it trailing from a backward point at which its presence is detected to the trailing edge of the sheet; and means for operating the folding device according to a folding program corresponding to the sensed length range and the determined residual length of each sheet to be folded.

The invention may be carried out effectively according to the embodiment disclosed in the aforesaid copending US. Pat. application, Ser. No. 137,549, for the folding of sheets having lengths not greater than the length of a table that constitutes the pathway, or track, along which the sheets are fed to the folder. On the other hand, when some of the sheets tobe folded will have lengths greater than the length of such a table, such for example as lengths exceeding cm., it is advantageous to carry out the invention according to a further development of it, such as by the embodiment described more particularly hereinbelow.

A principal feature of this further development is that when a sheet has reached the location adjacent to the folder where its leading edge is sensed, it is determined from the action of the sheet detector at the hindmost detection point of the pathway, or table, whether the sheet is longer or shorter than the length ranges defined by the several sheet detectors; and if it is longer, thus falling into an extra-long length range, folds are made at predetermined spacing in the leading part of the sheet until the hindmost detector no longer senses the presence of the sheet, i.e., until it detects that the trail ing edge of the part of the sheet remaining to be folded has been brought within a length range both limits of which are at determined distances from the folder. Then the remaining residual length of the sheet from its trailing edge up to the lower limit of that range is measured; and from this measurement is derived the location of at least one of the folds to be made in the part of the sheet then remaining unfolded, within the folding pattern employed for sheets of its determined length range.

Thus, when a sheet is longer than the greatest length that can lie between the measuring points provided along the pathway to the folder, the sheet is shortened by making folds in it at the desired intervals until the part of it remaining to be folded lies in a measured range between two of such points, whereupon the remaining residual length of that part and thus the location of a fold or folds to be made in it are determined, and it is folded, as if it were a sheet originally having its length.

Sheets of unlimited length can be folded into packets of desired standard size in this way. Moreover, the maximal length between measuring points, or feed table length, can be shorter than in the case of the first mentioned embodiment, and fewer measuring points, or sheet detectors, can be employed; so the apparatus for carrying out the invention can be of simpler design.

The objects, features and advantages of the invention will be further evident from the following description of a perferred embodiment of apparatus and practices for carrying out the invention. This description refers to the accompanying drawings, in which FIGS. la, 1b, 1c and 1d schematically represent four sets of folding patterns suitable for cross-folding sheets having different lengths;

FIG. 2 is a schematic representation of two sets of folding plans, or packet forms, for sheets having different lengths;

FIG. 3 is a schematic view of the sheet sensing and folding elements of an apparatus according to the invention, in which the sheet detecting elements along the pathway to the folding device are located suitably for folding sheets according to plan I of FIG. 2; and

FIG. 4 is a block diagram of an electronic computer circuit for controlling the operations of the apparatus.

As the invention relates mainly to the folding of a sheet in a direction parallel to one edge of the sheet, the following description will relate to such folding in one direction. It is to be understood, however, that the invention can be used also for folding in the direction perpendicular to the direction of the first folding. When reference is made herein to the length of the sheet, of a part of the sheet, or of a folded sheet, or packet, this refers to the dimension in the direction perpendicular to the folds which are made or to be made in the sheet.

The purpose of a folding apparatus of the kind here concerned is to reduce the dimensions of a large sheet of paper or similar material, for instance a drawing, to smaller dimensions which preferably are standardized, for instance to DIN A4 (210 mm.), so that it is easier to store away the sheets. Commonly the dimensions of a large sheet are not an exact multiple of the dimensions of the desired folded packet. For instance, when diazotype copies are made, even from originals having standard dimensions, the dimensions of the copies will generally deviate from the standard dimensions as a result of shrinkage due to moisture and temperature differences, cutting tolerances, etc., and will thus not be an exact multiple of the packet size wanted.

Accordingly, when a large sheet has been folded into a packet having the length desired, one or more layers or panels will be present, so-called intermediate folds, which are smaller than the desired length of the packet. By an intermediate fold or panel is meant such a shorter panel or layer of the packet. Preferably not more than two intermediate folds will be provided, as in this way the packet contains a minimal number of layers having less than the desired length. This, how ever, involves the following difficulty.

In the case of only two intermediate panels, the length of each of them is equal to half the difference between the length of the non-folded sheet and the greatest multiple, smaller than that length, of the desired length of the packet. This means that in practice small intermediate panels will occur, especially when the length of the sheet is only slightly greater than a multiple of the desired packet length, as often is the case. Aside from the fact that it is hardly practicable to fold them, such short intermediate panels are not aesthetic, and they tend to make the packet considerably thicker at one side than at the other, so that difficulties may result when storing the packets.

For this reason, a minimal length for the intermediate panels is preferably maintained. Since the intermediate panels must contain the difference between the length of the sheet and the amount of its length folded into panels having the desired packet length, when the maximal number of the latter is provided the intermediate panels will each have at most a length equal to half the desired packet length. Practically, this means that when folding a sheet into, for example, size DIN A4 having a length of 210mm, the intermediate panels would each have a length of at most mm if the packet contained the greatest practicable number of panels having the desired packet length. Accordingly, if a minimal panel length of more than 105 mm is to be assured, this requires in certain cases that more than two panels of the packet must be made shorter than the length of the packet.

FIG. 1a shows schematically variations of the folding pattern suitable for various lengths of the sheets, for a practice in which each sheet is folded into a packet having a length of 210 mm and an intermediate panel length of at least 105 mm. In FIG. lathe abscissa represent the original lengths of the sheets, while the ordinates represent the lengths of the packet panels, or layers. The number of layers necessary in order to reduce a certain sheet to the length of the packet is represented by the number of ordinate lines shown at the abscissa point corresponding to the length of the sheet. For sheet lengths up to 210 mm no fold is necessary. When the sheet is longer than 210 mm but shorter than 420 mm, the sheet is folded once, so that each panel is slightly longer than 105 mm if the sheet is but slightly longer than 210 mm and the panel length gradually increases to 210 mm as the length of the sheet increases to 410 mm. The sloped parallel lines extending between

point

105, 210 and

point

210, 420 represent the progression.

At sheet lengths between 420 and 630 mm the packet consists of three layers, including a first layer constantly of 210 mm length, as represented by the horizontal line at ordinate 210, and two intermediate panels the length of which gradually increases from 105 to 210 mm as the length of the sheet increases from 420 to 630 mm. The same pattern is repeated for sheet lengths between 630 and 840 mm, between 840 and 1,050 mm, etc., excepting that two, three, or a larger number of layers are formed with the constant packet length of 210 mm. For the sheets in each range two intermediate panels are formed with lengths which vary between 105 and 210 mm. The use of a smaller length for the minimal intermediate panel gives no extra advantage. At certain sheet lengths a choice can be made between folding patterns.

In practice it is often desirable that the free edge of the bottom layer of the folded packet be situated at the left-hand side, so as to be seen with the sheet, such as a drawing, in the normal posture for reading it. On the other hand, it is also desirable that the free edge of the top panel be situated at the right-hand side, so that the legend on the drawing, if any, can easily be identified. In order to fulfill these requirements, it is necessary that the packet be composed of an odd number of layers, or, which means the same thing, that the sheet be folded with an even number of fold lines.

If then a minimal intermediate panel length is to be assured, it is necessary in the case of sheets having a length greater than an even-number multiple of the de sired packet length but smaller than the next higher odd-number multiple thereof, to provide two intermediate panels in the packet; while in the case of sheets having a length greater than an odd-number multiple of the desired packet length but smaller than the next higher even-number multiple thereof, at least four intermediate panels must .be provided. I-Iere also there is a maximal length for the intermediate panels.

In the former case, of the sheet length being greater than an even number of packet lengths such that two intermediate panels must be provided, the same condition as mentioned above applies, namely, that the length of each intermediate panel is at least half of and at most equal to the desired packet length. In the second case, the sum of the minimal intermediate panel lengths must be between two and three times the desired packet length; so in the second case the lengths of the minimal intermediate panels can be chosen differently for different pairs of them. If their lengths are chosen to be at least half of the packet length, a folding pattern as represented schematically in FIG. lb is obtained.

FIG. 1b too is based, for example, on folding the sheets into a DIN A4 length of 210 mm. For a given point (sheet length) selected along the abscissa, the full lines on the ordinate from that point represent the number and the respective lengths of the panels (lay-' ers) of the packet formed by folding the sheet. The lengths of the intermediate panels are in this case at least I05 mm.

Another possible pattern for forming the desired packets is represented in FIG. 10, where in the cases of sheet lengths requiring at least four intermediate panels the lengths of these panels are chosen differently for different pairs of them. In this example there are two intermediate panels of minimally 120 mm and two intermediate panels of minimally 90 mm. In practice according to this example, as the sheet lengths increase within a certain range the lengths of the intermediate panels of minimally 120 mm can be increased first, until these have reached their maximum, after which the lengths of the intermediate panels of minimally mm increase until these have reached their maximum. Conversely, it is also practicable to keep the intermediate panels of minimally mm constant while first allowing the intermediate panels of minimally 90 mm to increase gradually, as represented by the broken lines in FIG. 1c.

Further in the case of FIG. 1c, for instance at sheet lengths increasing in the range between 630 and 1,050 mm, i.e., from 3 to 5 times the packet length, the four intermediate panels can be gradually increased simultaneously.

Finally, FIG. id represents a third variant whereby intermediate panels of minimally 60 mm and mm, respectively, are provided in the packets.

In principle, it is of course also practicable when working with lengths which require at least four inter mediate panels to make these panels so short that the sum of their lengths is smaller than the packet length. Also, more than four intermediate panels can be formed.

The invention preferably is carried out by the use of folding patterns according to FIG. 1c, for the following reasons.

In the folding of sheets according to FIG. la and lb, the folding pattern of a sheet slightly longer than a multiple of the desired packet length is different from that of a sheet slightly shorter than the same multiple. The desired packet length is commonly standardized. If some of the sheets to be folded have lengths nominally equal to a multiple of the desired packet length, but which in fact vary within certain tolerances, then various of these sheets will be folded in two different ways.

This disadvantage can be avoided to a great extent, upon taking into consideration the fact that the nominal sheet lengths normally are an even-number multiple of the standardized packet length, by using the folding patterns according to FIG. 10 or FIG. 1d. Among these the folding patterns according to FIG. 10 are preferred. Therefore, the following description will only deal with this manner of folding.

FIG. 2 schematically represents. two folding plans for cross-folding sheets of the standard sizes A3, A2, A1 and A0 into packets of A4 size, so as to produce either packets of 210 mm in length without a marginal fastening strip or packets of mm in. length having a marginal fastening strip of 20 mm in length (distance of protrusion from an edge of the packet). This figure also illustrates folding patterns suitable for various sheet lengths intermediate those of the standard sizes. Folding plan I of FIG. 2 corresponds with the folding patterns represented by the schematic showings in full lines on FIG. 1c.

FIG. 3 shows schematically at the left-hand side thereof a device of known type for folding sheets in zigzag manner. This device includes two pairs 1 and 2 of folding rollers which are reversible in their respective directions of rotation and a guide element 4 which can be moved back and forth between a position indicated at 3, in which it directs a sheet, or part of a sheet, into the bite of rollers 2, and a position indicated at 3 in which it directs the sheet or a part of it into the bite of rollers l. Rollers feed into the guide 4 a sheet guided to them by a channel 6 into which the sheet is fed by rollers 7 from a table 8. When a sheet is introduced into the folder by the rollers 7, if the guide element 4 is in position 3 the sheet is picked up by the rollers 1, and when a folding signal is given the direction of rotation of the roller pairs 1 and 2 is reversed and the guide element 4 is moved to position 3. Thus an undulation is formed in the sheet below the guide element 4, and this undulation is picked up by the rollers 2 so as to make a fold in the sheet at its location. By returning the guide element to position 3' and reversing the direction of rotation of the rollers 1 and 2, a second fold in the direction opposite to that of the first fold is made in the sheet. By continuing the operations in the way described the sheet can be folded zig-zig as many times as required, until it is completely folded in the desired packet and delivered through the folding rollers of pair 1 or pair 2.

Of course, other known types of zig-zag sheet folders can be used instead of the type illustrated in the drawmg.

The signals for moving the guide element back and forth and reversing the direction of rotation of the rollers 1 and 2 are produced by the action of sheet detectors spaced apart along the pathway of the sheets fed over the table 8 into the folding device and the action of the computing control system shown diagrammat ically in FIG. 4.

A first sheet sensing element or detector FDO is located in the channel 6 in a position to sense the presence of the leading edge of a sheet entering the folder. Sheet detectors FD], FD2, FD3 and FD4 are located in the sheet feed table 8 at distances from detector FDO corresponding to the limits of the sheet length ranges for which the various folding patterns are suited. The locations of these elements as represented in FIG. 3 are adapted to folding plan I of FIG. 2 and the corresponding showings of FIG. 10; so the operations of the folder as described in greater detail below relate in each instance to the folding of a sheet according to a pattern as represented in FIG. 1c and in the left-hand column of FIG. 2.

As explained in detail below, all the detectors, or sheet sensing elements, are activated by a signal from element FDO which is emitted as soon as the leading edge of a sheet arrives at FDO. Each detector then senses whether or not a part of the sheet is present at its location, and the hindmost of those of the detectors which sense the presence of a part of the sheet determines the first two folds which are then made.

If none of the detectors FDl through FD4 senses the presence of a sheet that has reached the location of FDO, the sheet ordinarily is not folded. However, such a short sheet can, of course, be folded in the manner described in the aforesaid copending application.

If detector FD4 senses the presence of the sheet, then two folds are made in the forward part of the sheet so that the distance between the leading edge and the first fold is equal to the desired packet length (e.g., 210 mm) or to that length plus the length of a fastening strip (e.g., 190 mm), and the distance between the first and second folds is equal to the desired packet length. Then, while the sheet keeps advancing over the table into the folder, detector FD4 senses whether the distance between the second fold and the trailing edge of the sheet continues to be greater or has become smaller than the distance between FDO and FD4. If element FD4 still senses the presence of a part of the sheet, then two additional folds are made in the advance part of the sheet so that the distance between the successive folds 5 is each time equal to the desired packet length. This manner of folding panels two by two is repeated until the detector FD4 no longer senses the presence of the sheet, i.e., until the distance between the fold last made and the trailing edge is smaller than the distance between FDI) and FD4.

If the detector FD4 does not sense, or when it no longer senses, a part of the sheet, the other detectors along the feed table determine between which two of the detectors the trailing edge of the sheet lies at the moment when the leading edge of the sheet, or the lo cation of the last previous fold to be made in the sheet, lies opposite to detector FDO.

If the trailing edge is then determined to lie between FD3 and FD4, two folds are made at intervals of 90 mm, the first of those being at a distance of 90 mm from the leading edge or the next preceding fold. As these two folds are being made the trailing edge moves past detector FD3. Since the sheet is advanced at a constant speed, the exact amount by which the length of the sheet, or of the part of it remaining to be folded, exceeds the distance between detectors FDO and FD3 can be determined by determining the time of the travel of its trailing edge from the location it occupied when determined to be lying between FD3 and FD4, to the location of detector FD3. The length of this trailing part of the sheet as so determined represents the residual length of the sheet and determines the locations where the folds of the next pair are to be made in the sheet.

Thus, after the two folds at intervals of 90 mm are made in the sheet, the two following folds are each made at a distance of 120 mm plus half the residual length, measured from the next preceding fold. Then a final panel of 210 mm in length remains, corresponding to the desired length of the packet.

If the length of the sheet to be folded is such that the trailing edge lies between FD2 and FD3 when the leading edge or the location of the last previous fold to be made is at FDO, the residual length is measured in relation to FD2, and two folds are made each at a distance of 120 mm plus half the residual length from the leading edge or the last previous fold. Again, a panel of 210 mm in length remains, corresponding to the desired packet length.

If, instead, the trailing edge then lies between FDI and FD2, the residual length is measured in relation to FDI, and intermediate folds are made at a distance of 90 mm plus half the residual length from the leading edge or the last previous fold.

As appears from FIG. 1c, the same folding pattern is used whether the trailing edge lies between FDI and FD2 or between FD2 and FD3; so, theoretcially, it would be possible to omit detector FD2. Practically this is not feasible without unduly complicating the control system, because the residual length could not then be determined due to the pre-requisite of the system as illustrated in FIG. 3 that when the trailing edge lies between FD2 and FD3, the next fold to be made will be at least 120 mm distant from the leading edge or the last preceding fold. The sheet can be advanced further through this distance without risk of losing control of the fold location, for the trailing edge will pass detector FD2 during this movement, whereupon the residual length and thus the location of the next fold can be determined. When the trailing edge has not yet passed detector FD2, the remaining length of the sheet portion from the location of the first fold to the trailing edge must also be at least 120 mm, and since half of this length is at least 60 mm, the location of the second next fold certainly lies at least 60 mm further. While the sheet is being advanced through a distance of at least 180 mm, its trailing edge certainly passes detector FD2 to enable determination of the exact value of the residual length and the exact location of the fold. If, however, detector FD2 were not present, the sheet could have been advanced by more than 180 mm while its trailing edge continued to lie between FDI and FD3; and if its trailing edge thus had not yet passed detector FDl, then the residual length could not be determined unless the control system were far more complicated.

Summarizing, folds are made in each sheet at locations as indicated in the following table, which relates to a packet length of either 210 mm or 190 mm and indicates fold locations as distances (lengths) in mm preceding the respective folds. The folding pattern for a packet length of 190 mm having a fastening strip of 20 mm (folding plan II in FIG. 2) can be derived from the folding pattern for a packet length of 190 mm by increasing the length of the first fold panel of the sheet by 20 mm. How this is effected will be explained below.

The operation of the control system of the folding apparatus will be explained below by reference to the block diagram of FIG. 4.

The detectors FDO up to and including FD4 produce signals which represent the presence or the absence of the paper or other sheet being transported along the table 8 or other pathway so as to be sensed by these elements. These signals are converted by a converter 10 into logical command signals (I state or state). The system includes pulse discs FCv and FCm which are coupled to the sheet transporting movement of the folding rollers or the feed rollers and 7, and which transmit counting pulses to the converter 10.

A logical command signal Cm is thus generated for use to measure the residual length. Also, a signal Cv is generated for counting off the programmed and calculated folding length.

The control system remains in an inactive or rest condition as long as detector FDO is not activated. However, as soon as the leading edge of a sheet arrives at the location of detector FDO, a starting generator 11 is actuated by a signal FDO issued by the convertor 10. The starting generator 11 now generates a signal Do. This signal can have a delay or retardation time, so that the sheet will advance a distance equal to the length of the side fastening strip during the delay time. Upon the command of signal Do the conditions of the signals D1 up to and including D4 are recorded in a buffermemory unit 12. Depending upon these conditions recorded in the buffer-memory unit 12, the program register 13 determines which one of the folding programs G1, G2 G5 (see Table A), is to be executed. If program G2 or G3 is indicated, so a program with a variable folding length, the program register 13 by emission Gi simultaneously actuates a selection circuit 14 and opens a gate 15 to let the residual length counting pulses Cm pass through this gate. The third input of gate 15 is the sheet direction signal Di. The residual length counting pulses Cm are then transmitted via gate 15 to a two-divider 16 which halves the frequency of the pulse signal Cm, so that half of the residual length /2A) is measured in a residual length counter 17. When the sheet of paper again uncovers the detector FD2 or FD3, the gate 15 closes so that the counting pulses Cm are no longer permitted to pass. The residual length determination has then been finished.

A gate 18 in the circuit has three entries, into which the signals FDO, Cv and Q0 are transmitted. The signal Q0 is an inversion of the 00 signal which originates from the selection circuit 14. The signal Q0 initially has the 1 state.

Gate 18 is opened by signal FDO, so that the counting pulses Cv will be transmitted to a counter 19. A decoding unit 20, in which the fixed values of Table A are recorded, determines when the fixed number of pulses of the program G2 or G3 (e.g., pulses equivalent to a distance of or mm) has been counted. The output signal Ni of the decoding unit 20 then actuates the selection circuit 14, so that the condition of the Q0 signal modifies. Thus the gate 18 is blocked, so that the counting pulses Cv are no longer conducted to the counter 19. The pulses Cv still to follow are now transmitted to a counter 22 via a gate 21, which is opened by the signal Q0.

During the counting the content of the counter 22 is continually compared by a comparing unit 23 with the content of the residual length counter 17. When the contents of the counters l7 and 22 are equal, a signal S is generated, which in cooperation with the 00 signal opens a gate 24, so that a folding pulse T is generated.

When the program register 13 establishes that the folding program to be executed is one having no variable factor, a selection circuit 25 is actuated by the Gi signal of the program register 13 and by the Ni signal of the decoding unit 20. The Ni signal is generated after the fixed folding length recorded in decoding unit 20 has been counted. Thus a pulse R is generated, which in turn generates a folding pulse T via gate 24.

At the start of the feeding of the sheet, the sheet moves through guide 4 to the left and between the folding rollers l. The folding pulse generated as described above actuates a two-divider 26, so that one of the two outputs of this two-divider, in this case the signal VR, receives the 1 state. Upon this signal the direction of rotation of the folding rollers l and 2 is reversed, and a fold is formed. The sheet now is guided by element 4 in the direction to pass to the right between the folding rollers 2. The folding pulse T serves also as a reset signal by which the counters l9 and 22 are brought back into their zero position, while the buffer memory 12, the program register 13 and the residual length counter 17 keep in the same condition. Now the same folding length as that for the first fold is measured off, after which a second folding pulse T is generated and the VL signal from divider 26 receives the 1 state.

By this second folding pulse the direction of rotation of the folding rollers 1 and 2 is again reversed, and the

counters

19 and 22 are brought back into their zero position. Because the VL signal has received the 1 state, the residual length counter is now set back to the zero position, and the signals of the detection elements at that moment are again recorded in the memory unit; so a new folding program can now be selected by the control system.

Thus, after each two folds the whole circuit is restored to its original condition, and it immediately makes a new observation of the position of the sheet relative to the detectors FDl FD4, for the following two folds if the remaining length of the sheet not yet folded is such that more folds are required. This cycle is repeated until the entire sheet has been folded into the selected packet length. For instance, two folds made according to program G may be followed by two folds made according to program G2, if the sheet is of A1 length (841 mm); or may be followed by two folds made at 90 mm intervals according to program G4, and then by two more folds made at 189.5 mm intervals according to program G3, if the sheet is of A0 length 1,189 mm). The corresponding packet forms are illustrated in FIG. 2, Plan I.

It will be evident to those skilled in the art that the invention is not limited to the example described above and that numerous modifications can be employed without departing from the substance of the invention, which is intended to be defined by the appended claims.

What is claimed is:

1. A method of folding large sheets having any of various lengths individually into respective packets having a desired standard length in the direction transverse to the folds, which comprises: feeding the sheets individually along a measuring pathway to and then through a folding means operable to form in a sheet moving therethrough successive folds in zigzag disposition at locations spaced apart along the sheet; as each sheet moves to said folding means determining in which one of a plurality of successive predetermined sheet length ranges the length of the sheet lies by sensing simultaneously a certain location of the leading edge of the sheet and the presence or absence of the sheet at respective points spaced apart along said pathway at the limits of said length ranges, and measuring the residual length if any exists by which the sheet then trails behind the lower limit of one of said length ranges; and as the sheet moves through said folding means operating the latter at successive intervals the number and the respective distances of which, so the number and spacings of said folds formed in the sheet, are determined according to the magnitudes of said determined length range and said residual length.

2. A method according to claim 1, said feeding of the sheets being effected at a determined speed and said measuring of the residual length of each sheet being effected by measuring the time of the travel of the trailing edge of the sheet from a sensed location thereof between two of said points to the location of the one of said two points nearer to said folding means.

3. A method according to claim 1, as applied to sheets having lengths of about two to between three and four times said desired packet length, which comprises forming in each sheet an even number of said folds, with the last of said folds at a distance from said trailing edge equal to said desired packet length and with the first of said folds at a location such that said leading edge lies in the formed packet at a distance from said trailing edge equal to said packet length or to the same plus the width of an end strip of the sheet provided for attachment of the formed packet, and forming said first and last folds and any intermediate folds at respective distances from the respective next preceding folds and said leading edge which do not exceed said packet length and the sum of which is equal to the length of the sheet less said packet length.

4. A method according to claim 1, as applied to sheets having lengths of three to four or more times said desired packet length, which comprises forming in each sheet an even number of said folds, with the first of said folds at a distance from said leading edge approximately equal to said desired packet length or to the same plus the width of an end strip of the sheet provided for attachment of the formed packet, and with the last of said folds at a distance from said trailing edge equal to said packet length, and forming in the sheet between the first and last folds at least two intermediate folds at respective distances from the respective next preceding folds which correspond to a fraction of said packet length plus an even-number fraction of said residual length but do not exceed said packet length.

5. A method according to claim 4, wherein, when the sheet length lies between an even-number multiple and the next higher odd-number multiple of said packet length, two of such intermediate folds at such respective distances are formed in the sheet and any other intermediate fold therein is formed at a distance approximately equal to said packet length from the fold next preceding it.

6. A method according to claim 4, wherein, when the sheet length lies between an odd-number multiple and the next higher even-number multiple of said packet length, four of such intermediate folds at such respective distances are formed in the sheet and any other intermediate fold therein is formed at a distance approximately equal to said packet length from the fold next preceding it.

7. Apparatus for folding large sheets having any of various lengths individually into respective packets having a desired standard length in the direction transverse to the folds, including folding means operable by successive impulses to form in a sheet moving therethrough successive folds in zig-zag disposition at locations spaced apart along the sheet, a table defining a sheet measuring pathway, and means for feeding the sheets individually along and from said table to and then through said folding means, sheet detection means including an element for sensing at a certain location the leading edge of a sheet moving to said folding means and a plurality of elements associated with said table for simultaneously sensing the presence or absence of said sheet at respective points spaced apart along said pathway, said points being located at the lower limits of a plurality of successive sheet length ranges so that a particular one of said ranges in which said sheet lies is determined by the operation of said sensing elements, means operative when said particular length range is determined for measuring the residual length if any exists by which the sheet then trails the lower limit of one of said length ranges, and control means responsive to said detection means and to said measuring means for operating said folding means at successive intervals the number and the distances of which, so the number and spacings of said folds formed in the sheet, are determined according to the magnitudes of said determined length range and said residual length.

8. Apparatus according to claim 7, said sheet feeding means being operative to feed each sheet at a determined speed and said means for measuring said residual length including means for measuring the time of the travel of the trailing edge of the sheet from a sensed location thereof between two of said points to the location of the one of said two points nearer to said folding means.

9. Apparatus according to claim 7, said means for measuring said residual length comprising a pulse sender emitting pulses having a frequency proportional to the speed at which the sheet is fed to said folding means and means for counting said pulses during the time period of movement of the trailing edge of the sheet from a location thereof sensed to be between two of said points to the one of said two points nearer to said folding means.

10. Apparatus according to claim 7, said control means including memory means for recording signals corresponding to the conditions sensed by said sensing elements, register means for progressively sensing a repetitive clock signal, and means for comparing the state of signals sensed by said register means with that of the signals recorded by said memory means and fixing a signal output of said register means corresponding to a condition thereof in which the signal input thereto corresponds in extent to the signals recorded by said memory means when a sheet is sensed at the lower limit of said determined length range.

11. Apparatus according to claim 7, said means for measuring said residual length comprising a pulse sender emitting pulses having a frequency proportional to the speed at which the sheet is fed to said folding means and means for counting said pulses during the time period of movement of the trailing edge of the sheet from a location thereof sensed to be between two of said points to the one of said two points nearer to said folding means, said control means including memory means for recording signals corresponding to the conditions sensed by said sensing elements, register means for progressively sensing a repetitive clock signal, and means for comparing the state of signals sensed by said register means with that of the signals recorded by said memory means and fixing a signal output of said register means corresponding to a condition thereof in which the signal input thereto corresponds in extent to the signals recorded by said memory means when a sheet is sensed at the lower limit of said determined length range.

12. Apparatus according to claim 11, and means for blocking access of said pulses to said counting means when the condition sensed by the sensing element at said lower limit changes from the presence to the absence of the sheet.

l3. Apparatus according to claim 12, said blocking means including a pulse generator for comparing said signal output of said register means with signals corresponding to the conditions sensed by said sensing elements and gate means responsive to a signal from said generator to stop passage of said pulses to said counting means.

14. Apparatus according to claim 11, further comprising means for converting said pulses into signals having either of two reduced frequencies and means controlled by said signal output of said register means for selecting and transmitting to said counting means the signals having one of said redluced frequencies.

15. Apparatus according to claim 12, further com prising means for emitting a pulse to complete the operating of said folding means after the occurrence of a number of said pulses corresponding to said condition of said register means and the input of said counting means.

16. Apparatus for folding large sheets having any of various lengths individually into respective packets having a desired standard length in the direction transverse to the folds, including folding means operable by successive impulses to forms in a sheet moving there through successive folds in zig-zag disposition at locations spaced apart along the sheet and means for feeding the sheets individually along and from a fixed pathway to and then through said folding means, sheet detection means including a first element for sensing at a certain location the leading edge of a sheet moving to said folding means and a plurality of elements at points spaced apart along said pathway for simultaneously sensing the presence or absence of said sheet at respective ones of said points, means operative to actuate said folding means so as to make a predetermined number of initial folds at predetermined spacings in the sheet if when the leading edge of the sheet reaches said first element the presence of the sheet is sensed at the hindmost of said points, and to repeat such actuation of said folding means if after said number of folds the presence of the sheet is still sensed at said hindmost point, until the trailing edge of the sheet lies in a length range between two of said points, and means operative when the trailing edge of the sheet is sensed to lie between two of said points, either at the time of the leading edge reaching said first element or upon such initial folds having been made in the sheet, to select a folding pattern suited for the length range defined between said two points, then to measure the distance if any by which the trailing edge of the sheet lies behind the one of said two points nearer to said folding means, and to actuate said folding means so as to make final folds in the sheet in a number and at locations derived from said pattern and from said measured distance.

17. Apparatus according to claim 16, said predetermined spacings being equal to the desired length of the packets being formed by the folding of the sheets.

18. Apparatus according to claim 16, said predetermined number of initial folds being two.

19. Apparatus according to claim 16, the number of said final folds being two.

20. Apparatus according to claim 16, said last recited means being operative to make two such final folds in the sheet when the said length range is greater than an even-number multiple but less than the next higher odd-number multiple of the desired length of the packet into which the sheet is being folded, and to make four such final folds therein when said length range is greater than an odd'number multiple but less than the next higher even-number multiple of said desired packet length.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. ,9 1 Dated August 2'7, 197

Inventor(s) Josef Marie Jan Verten It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column line 65, chair-gs "to to read to 120 mm.

Signed and Sealed this nineteenth D f August 1975 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Altesling ()ffieer (mnmissimu'r 0f Parents and Trademarks FORM P0-1050 (10459) uscoMM-oc wan-p09 u.s. covzmmern nuu'rmc ornc: B69. 930

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 5, 51,9 7 Dated August 197Lt Inventor(s) Josef Marie van Herten Q It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading, beneath Foreign Application Priority Data" should read: Apr. 2h, l970 Netherlands 7006050 Column 10, line 27, "00" should read 00 Column 10, line 28, the first "00" should read 0o Column 10, line 29; "00" should-' read 0o Signed and Emalcd this twenty-third Of March 1976 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner oj'Patenls and Trademarks G

Claims

13. Apparatus according to claim 12, said blocking means including a pulse generator for comparing said signal output of said register means with signals corresponding to the conditions sensed by said sensing elements and gate means responsive to a signal from said generator to stop passage of said pUlses to said counting means.

14. Apparatus according to claim 11, further comprising means for converting said pulses into signals having either of two reduced frequencies and means controlled by said signal output of said register means for selecting and transmitting to said counting means the signals having one of said reduced frequencies.

15. Apparatus according to claim 12, further comprising means for emitting a pulse to complete the operating of said folding means after the occurrence of a number of said pulses corresponding to said condition of said register means and the input of said counting means.

16. Apparatus for folding large sheets having any of various lengths individually into respective packets having a desired standard length in the direction transverse to the folds, including folding means operable by successive impulses to forms in a sheet moving therethrough successive folds in zig-zag disposition at locations spaced apart along the sheet and means for feeding the sheets individually along and from a fixed pathway to and then through said folding means, sheet detection means including a first element for sensing at a certain location the leading edge of a sheet moving to said folding means and a plurality of elements at points spaced apart along said pathway for simultaneously sensing the presence or absence of said sheet at respective ones of said points, means operative to actuate said folding means so as to make a predetermined number of initial folds at predetermined spacings in the sheet if when the leading edge of the sheet reaches said first element the presence of the sheet is sensed at the hindmost of said points, and to repeat such actuation of said folding means if after said number of folds the presence of the sheet is still sensed at said hindmost point, until the trailing edge of the sheet lies in a length range between two of said points, and means operative when the trailing edge of the sheet is sensed to lie between two of said points, either at the time of the leading edge reaching said first element or upon such initial folds having been made in the sheet, to select a folding pattern suited for the length range defined between said two points, then to measure the distance if any by which the trailing edge of the sheet lies behind the one of said two points nearer to said folding means, and to actuate said folding means so as to make final folds in the sheet in a number and at locations derived from said pattern and from said measured distance.

19. Apparatus according to claim 16, the number of said final folds being two.

20. Apparatus according to claim 16, said last recited means being operative to make two such final folds in the sheet when the said length range is greater than an even-number multiple but less than the next higher odd-number multiple of the desired length of the packet into which the sheet is being folded, and to make four such final folds therein when said length range is greater than an odd-number multiple but less than the next higher even-number multiple of said desired packet length.