BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a lateral perforation forming apparatus for a form printing machine. More particularly, the invention relates to an arbitrarily positioned lateral perforation forming apparatus for forming a lateral perforation at an arbitrary position or a selected position in a continuous web paper printed by a form printing machine, depending upon a printed image. 
     2. Description of the Related Art 
     Since a form printing machine performs a printing by means of a plate cylinder having a predetermined peripheral length, printing on a continuous web paper repeatedly makes a print per predetermined length in a feeding direction of the continuous web paper, namely makes repeated prints of the same image. Then, when a lateral or cross line perforation aligned in a perpendicular direction to a longitudinal direction of the continuous web paper is formed in a part of the printed image of such repeated prints of the same image, it is typical to perform a formation of the perforation by means of a perforation forming cylinder or a roulette cylinder having the same peripheral length as the plate cylinder in a similar manner to printing. In such conventional apparatus, the perforation formation is inherently performed sequentially and repeatedly for all printed images. Therefore, it has not been possible to form the lateral perforation only for preliminarily selected image. 
     In addition to the above-mentioned typical prior art, there has been known the conventional lateral perforation forming apparatus which can form a perforation to preliminarily selected printed image. Such perforation forming apparatus have been disclosed in Japanese Patent No. 2559036 and Japanese Unexamined Patent Publication (Kokai) No. Heisei 9-76460. 
     The former apparatus as disclosed in Japanese Patent No. 2559036 includes a rotary body driving source separately from a paper drive mechanism for feeding a continuous web paper. The disclosed apparatus further comprises a rotary body having a plurality of perforation forming portions performing a formation of lateral perforation in the continuous web paper and inactive portions located between the perforation forming portions and not contacting with the continuous web paper, a perforation forming pattern input portion for inputting a perforation forming pattern to be formed by the perforation forming portion of the rotary body, a detector for detecting a feed position and a feed speed of the continuous web paper fed by the paper drive mechanism, and a control unit, in response to a continuous web paper feed amount signal generated by the detector, adjusting a rotation speed of the rotary body to the same speed as the paper feeding speed when each perforation forming portion of the rotary body performs the formation of perforation for the continuous web paper, and electrically controlling the driving source of the rotary body to adjustably increase and decrease a rotation speed of the rotary body relative to the feed speed of the continuous web paper upon non-forming of perforation where each inactive portion of the rotary body is placed in opposition to a feeding path of the continuous web paper, and whereby adjusting interval of a plurality of perforation forming position of the continuous web paper. 
     On the other hand, the latter apparatus as disclosed in Japanese Unexamined Patent Application No. Heisei 9-76460 is originally adapted for cutting the continuous web paper at predetermined positions. However, the apparatus is also applicable to a formation of the lateral perforation. The apparatus comprises a cutting cylinder (roulette cylinder), which is disposed on an upstream side of an oscillatory shooter assembly in a web paper traveling path. The cutting cylinder includes a full edge type cutting member (lateral roulette edge) which is protruded from a peripheral surface of the cutting cylinder and which forms the cross line of cuts (lateral perforation) interposed by at least one small uncut portion in the continuous web paper. The cutting cylinder is synchronously rotated with the feeding speed of the continuous web paper for forming the cross line of cuts (lateral perforation) in response to a signal detecting the predetermined feeding length of said continuous web paper. In the construction set forth above, bearing boxes supporting both ends of the cutting cylinder are supported on frames for eccentric rotation relative to a center of the cutting cylinder so that the cutting cylinder is moved toward and away from an impression cylinder (receptacle cylinder) according to eccentric rotation of the bearing box for forming the cross line of cuts (forming lateral perforation) in the continuous web paper upon contacting of the cutting cylinder with the impression cylinder. 
     The former prior art is so-called a single motor type lateral perforation forming apparatus and encounters the following problem. 
     The disclosed apparatus performs the formation of lateral perforation by driving a stand-alone lateral perforation forming motor provided independently of the motor for paper feeding, in synchronism with a signal from the control unit. However, due to an inertia load of the lateral roulette cylinder and an impact upon the formation of perforation, the rotation and perforation formation may be performed in a condition where the position of the roulette edge is dislocated from the position synchronized with the signal to cause an error in the perforation forming position in the product. 
     The foregoing phenomenon becomes more significant at higher speed operation where the inertia load of the lateral roulette cylinder becomes greater. For this reason, in order to facilitate an accurate control of rotation of the lateral roulette cylinder in high speed range, the lateral roulette cylinder having small diameter, e.g. about 80 mm in diameter, inducing smaller inertia load, is employed. However, it causes a problem that the lateral perforation is not formed for a deflecting deformation of the lateral roulette cylinder. In addition, the rotation of the lateral roulette cylinder has to be accurately synchronized with flow of the continuous web paper. Since the rotating drive source is the single motor, a large servo motor (pulse motor) having high torque becomes necessary. Then, a drive control portion for the servo motor having large capacity has to be used to perform the accurate synchronization, to result in high cost. 
     On the other hand, the latter prior art does not require the roulette position control depending upon motor control which encounters the drawback in the former prior art, but can form perforation at accurate position in mechanical synchronous operation. However, the latter prior art encounters the following problem. 
     Namely, since the bearing box supporting the lateral roulette cylinder rotates eccentrically relative to the center of the lateral roulette cylinder at every time of formation of lateral perforation, a play should be caused by wearing in a rotary support of the frame rotatably supporting the bearing box through repeated rotating operation, to result in an accident that the lateral perforation is not formed. On the other hand, accurate fitting between the bearing box and the frame is difficult to establish, both the components should be finished for avoiding play, and thermal expansion can be caused in the fitting portion to make the bearing box to difficult to rotate for frequent rotation of the bearing box, to require a large capacity driving source, such as a liquid pressure cylinder, for driving the bearing box to rotate overcoming the resistance increased due to thermal expansion. If the driving source becomes large, response characteristics to a control command is degraded to cause a failure in movement of the roulette cylinder toward and away from the receptacle cylinder. 
     Therefore, an anti-friction bearing, such as needle bearing, may be used in rotating support portion of the bearing box in the frame. However, cost becomes high. Furthermore, since such anti-friction bearing is not durable against impact load and vibration load to cause play and damage at early timing in the anti-friction bearing. 
     SUMMARY OF THE INVENTION 
     The present invention has been worked out in view of the drawbacks in the prior art set forth above. Therefore, it is an object of the present invention to provide an arbitrarily positioned lateral perforation forming apparatus which can form lateral perforation in an arbitrary position or a selected position of a continuous web paper with small control amount to permit simplification of a control system, and can accurately form lateral perforation at the arbitrary position or the selected position. 
     In order to accomplish the above-mentioned objects, a arbitrarily positioned lateral perforation forming apparatus, according to the present invention, comprises: 
     a lateral roulette cylinder projecting a lateral roulette edge on its outer periphery, arranged on one side of a continuous web paper, and rotating in a traveling direction of the continuous web paper; 
     a receptacle cylinder projecting an edge receptacle portion opposing to the lateral roulette edge of the lateral roulette cylinder, on its outer periphery, arranged on the other side of the continuous web paper, rotating in the traveling direction of the continuous web paper, and forming a lateral perforation in the continuous web paper when the edge receptacle portion is in opposition to the roulette edge; 
     a drive system for rotating the lateral roulette cylinder and the receptacle cylinder in synchronism with traveling of the continuous web paper; 
     a first differential mechanism disposed in an element connected to one of the lateral roulette cylinder and the receptacle cylinder in the drive system, causing difference in rotational phases of the lateral roulette cylinder and the receptacle cylinder by varying rotation of a differential shaft thereof for selectively placing the edge receptacle portion at a position opposing to the roulette edge and a position circumferentially offsetting from the roulette edge; and 
     a first control unit for controlling rotation of the differential shaft of the first differential mechanism. 
     In addition to the foregoing construction, it is preferred that the arbitrarily positioned lateral perforation forming apparatus further comprises a second differential mechanism disposed in an element commonly connected to the lateral roulette cylinder and the receptacle cylinder in the drive system, and varying a position to be formed with the lateral perforation in the continuous web paper by making rotations of the lateral roulette cylinder and the receptacle cylinder synchronous with traveling of the continuous web paper by varying rotation of a differential shaft thereof; and. 
     a second control unit for controlling rotation of the differential shaft of the second differential mechanism. 
     In addition to the foregoing construction, it is preferred that the arbitrarily positioned lateral perforation forming apparatus further comprises: 
     a mark sensor reading a mark printed on the continuous web paper and inputting a mark read signal to the first control unit, 
     the first control unit is responsive to the mark read signal for driving the first differential mechanism to perform a formation of lateral perforation. 
     Furthermore, the first differential mechanism may be disposed in the element connected to the receptacle cylinder of the drive system or in the element connected to the roulette cylinder in the drive system. 
     With the construction set forth above, the lateral roulette cylinder and the receptacle cylinder are driven to rotate along the traveling direction of the continuous web paper by the drive system. Then, at this time, by rotating the differential shaft of the first differential mechanism, the rotational phase of one of the lateral roulette cylinder and the receptacle cylinder is shifted relative to the rotational phase of the other. 
     By causing difference in the rotational phases, when the lateral roulette edge of the lateral roulette cylinder is placed in opposition to the edge receptacle portion projecting on the receptacle cylinder, the lateral perforation can be formed in the continuous web paper traveling therebetween. The formation of the lateral perforation can be arbitrarily performed by controlling the first differential mechanism via the first control unit. Furthermore, by only shifting the rotational phase of one of the lateral roulette cylinder and the receptacle cylinder relative to the rotational phase of the other, one of the cylinders can be selectively placed at the active position where the lateral perforation is formed and inactive position where the lateral perforation is not formed. Thus, the lateral perforation can be arbitrarily formed with small control amount. Accordingly, the control system can be simplified, and the lateral perforation can be formed at arbitrary position with high precision. 
     Also, by rotation the differential shaft of the second differential mechanism via the second control unit, rotation of the lateral roulette cylinder and the receptacle cylinder can be synchronous with traveling of the continuous web paper. By this, the position to be formed with the lateral perforation can be arbitrarily varied in the longitudinal direction (traveling direction) of the continuous web paper. 
     Further, the actuation of the first differential mechanism is performed by reading the mark by the mark sensor and on the basis of the read signal. By this, only on the portion of the continuous web paper where the mark is printed, the lateral perforation can be formed. For example, the lateral perforation can be formed at a predetermined position of a sheet with the mark which is preliminarily printed on the continuous web paper. By this the lateral perforation can be selectively formed at the portion of the preliminarily selected image. 
     The present invention will be understood more fully from the detailed description given herebelow and from the accompanying drawings of the preferred embodiment of the present invention, which, however, should not be taken to be limitative to the invention, but are for explanation and understanding only. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is an explanatory illustration showing a general construction of a perforation forming section of a form printing machine including one embodiment of an arbitrarily positioned lateral perforation forming apparatus according to the present invention; 
     FIG. 2 is a plan view of one example of a continuous web paper to be formed perforation by the perforation forming section; 
     FIG. 3 is an explanatory illustration showing one example of the arbitrarily positioned longitudinal perforation forming apparatus in the perforation forming section; 
     FIG. 4 is an explanatory illustration showing another example of the arbitrarily positioned longitudinal perforation forming apparatus; 
     FIG. 5A is a section taken along line VA—VA of FIG. 3; 
     FIG. 5B is a section showing a condition where a shifting member is rotated in FIG. 5A; 
     FIG. 6 is an explanatory illustration showing a construction of the shown embodiment of the arbitrarily positioned lateral perforation forming apparatus in the perforation forming section; 
     FIG. 7 is a section showing one example of a differential mechanism in the shown embodiment; 
     FIG. 8A is a section taken along line VIIIA—VIIIA of FIG. 6; 
     FIG. 8B is a section showing a condition where an edge receptacle portion of the receptacle cylinder is matched to a roulette edge of the lateral roulette cylinder; 
     FIG. 9 is a block diagram showing one part of the control system in the shown embodiment; and 
     FIG. 10 is a block diagram showing another part of the control system in the shown embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention will be discussed hereinafter in detail in terms of the preferred embodiment of the present invention with reference to the accompanying drawings, i.e. FIGS. 1 to  10 . In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be obvious, however, to those skilled in the art that the present invention may be practiced without these specific details. In other instance, well-known structures are not shown in detail in order to avoid unnecessarily obscure the present invention. 
     In the drawings, the reference numeral  1  denotes a fold line lateral perforation forming apparatus for forming a lateral perforation  3  for a fold line in a continuous web paper  2  which is fed sequentially, at predetermined interval as shown in FIG.  2 . The lateral perforation forming apparatus has a construction well known in the art and comprises a fold line lateral roulette cylinder  4  and a receptacle cylinder  5  rotating in synchronism with a traveling speed of the continuous web paper  2 . The lateral perforation  3  for the fold line is formed per a given interval P in the continuous web paper  2  by means of a lateral roulette edge  6  fixed on the fold line lateral roulette cylinder  4  by cooperated rotations of both cylinders  4  and  5 . Then, the lateral perforation forming apparatus  1  for the fold line is connected to a drive shaft S of a machine via a drive gear train (drive system) G 1 . 
     In the drawings, the reference numeral  7  denotes an arbitrarily positioned longitudinal perforation forming apparatus which is located downstream the lateral perforation forming apparatus  1  for the fold line in a traveling direction of the continuous web paper  2  and forms a longitudinal or in-line perforation  8  aligned in the longitudinal direction of the continuous web paper, at an arbitrary position in the continuous web paper  2  along a traveling direction thereof. 
     On the other hand, in the drawing, the reference numeral  9  denotes an arbitrarily positioned lateral perforation forming apparatus which located downstream the arbitrarily positioned longitudinal perforation forming apparatus  7  and forms a lateral perforation  10  at an arbitrary position in the continuous web paper  2  along the traveling direction thereof. 
     Then, in the drawings, the reference numeral  11  denotes a mark sensor for reading a mark  12  preliminarily set by printing on the continuous web paper  2 . The mark sensor  11  is provided on upstream side of the arbitrarily positioned longitudinal perforation forming apparatus  7 . 
     Next, the construction and function of the arbitrarily positioned longitudinal perforation forming apparatus will be discussed with reference to FIGS. 1 and 3 to  5 . In the drawings, the reference numerals  15  and  16  are respectively a longitudinal roulette cylinder and a receptacle cylinder located in opposition across a traveling path of the continuous web paper  2 . 
     A longitudinal roulette cylinder  15  is constructed with a first rotary shaft  19  supported on frames  17  and  18  on both sides and a disc-shaped longitudinal roulette edge  20  fixed on the first rotary shaft  19  as positioned in an axial direction and provided roulette edge on its outer periphery. A plurality of, for example two the longitudinal roulette edges  20  are provided with a predetermined interval d. Then, the longitudinal roulettes  20  are fixed by fastening screws  21 . By loosening the fastening screws  21 , the longitudinal roulettes  20  are movable in the axial direction. The longitudinal roulette  20  is locked on the first rotary shaft  19  in a rotating direction by means of a key  19   b.    
     The receptacle cylinder  16  is constructed with a second rotary shaft  22  supported on frames  17  and  18  on both sides and a disc-shaped edge receptacle portion  23  engaged with the second rotary shaft  22  slidably in axial direction and provided with edge receptacle portion  23   a  of projective step shape which contacts with (or is placed in opposition to across a fine gap) the longitudinal roulette edge  20  of the longitudinal roulette cylinder  15 . A plurality of the edge receptacle plates  23  of which number corresponds to number of the longitudinal roulette edge  20  (i.e. two) are engaged with the second rotary shaft  22 . On the other hand, a length in the circumferential direction of the edge receptacle portion  23   a  of the edge receptacle plate  23  corresponds to a length b of the longitudinal perforation  8  shown in FIG.  2 . The edge receptacle plate  23  is locked on the second rotary shaft  22  in the rotating direction by means of a key  22   b.    
     The first and second rotary shafts  19  and  22  are extended outwardly from one frame  17 . On the extended portions of the first and second rotary shafts  19  and  22 , mutually meshing gears  24  and  25  are integrally engaged, respectively, to rotate in mutually opposite directions. One gear  25  is meshed with an input gear  26  of a drive gear train G 2  for forming the longitudinal perforation, and the drive gear train G 2  is connected to the drive shaft S of the apparatus. 
     The reference numeral  27  denotes an edge receptacle plate moving device for moving the edge receptacle plate  23  in axial direction. The edge receptacle plate moving device  27  is constructed with a threaded shaft  29  rotatably supported on the frames  17  and  18  on both sides and having feeding thread  28  on the outer periphery, a sleeve  30  threadingly engaged with the feeding thread  28  of the threaded shaft  29  and a shifting member  31  engaged with the sleeve  30  movably in the axial direction. To the threaded shaft  29 , a servo motor  32  is connected. It should be noted that, in certain construction of the servo motor  32 , a speed reduction gear unit, such as a harmonic drive (tradename) which will be discussed later and can obtain a large reduction ratio, may be interposed between the servo motor  32  and the threaded shaft  29 . 
     The shifting members  31 , number of which corresponds to number of the edge receptacle plates  23 , are engaged with the sleeves  30  with an interval d the same as the interval of the edge receptacle plates  23 , and is fixed to the sleeve by the fastening screws  33 . The shifting members  31  are movable in the axial direction by loosening the fastening screws  33 . To the sleeve  30 , an arm  34  is projected in a direction perpendicular to the axial direction. To the arm  34 , a rotation stopper shaft  35  projected on one frame  17  in the axial direction is engaged slidably in the axial direction. 
     As shown in FIGS. 3,  5 A and  5 B, the shifting members  31  are provided with grooves  36  on parts of the peripheral edge portions, respectively. The grooves  36  are engaged with peripheral edge portions of the edge receptacle plates  23  so that the edge receptacle plates  23  are moved in the axial direction along the second rotary shaft  22  by axial movement of the shifting members  31 . On the peripheral edge portions of the shifting members  31 , cut-outs  37  is provided at a portion adjacent to the groove  36  in the circumferential direction, without causing interference with the edge receptacle plates  23  in the axial direction, respectively. By rotating the shifting members  31  about the sleeve  30  as shown in FIG.  5 B and thus placing the cut-outs  37  in opposition to the peripheral surface of the edge receptacle plates  23 , engagements between the edge receptacle plates  23  and the shifting members  31  are released, respectively. 
     In the arbitrarily positioned longitudinal perforation forming apparatus  7 , the gears  24  and  25  are driven in mutually opposite directions by rotation of the input shaft  26  of the drive gear train G 2  for formation of the longitudinal perforation, for rotatingly driving the longitudinal roulette cylinder  15  and the receptacle cylinder  16  to rotate at a peripheral speed at which the longitudinal roulette edges  20  and the edge receptacle plates  23  respectively match with the feeding speed of the continuous web paper  2 . 
     The edge receptacle plate  23  is normally offset in axial direction relative to the longitudinal roulette edge  20 . The threaded shaft  29  of the edge receptacle plate moving device  27  is driven to rotate by the servo motor  32  to move the sleeve  30  in the axial direction. By the shifting members  31  integrally moving with the sleeve  30  , the edge receptacle plates  23  are moved in the axial direction. Then, when the edge receptacle plates  23  are placed in opposition with the longitudinal roulette edges  20 , the longitudinal perforation  8  is formed in the continuous web paper  2  over a length corresponding to the length of the edge receptacle portion  23   a  of the edge receptacle plate  23 . Thereafter, when the edge receptacle plate moving device  27  is operated in the opposite direction by revolution of the servo motor  32  in reverse direction, the edge receptacle plates  23  are offset in the axial direction relative to the longitudinal roulette edges  20  so as not to form the longitudinal perforation  8 . 
     The positions and interval of forming the longitudinal perforations  8  are determined by positions of the longitudinal roulette edges  20  and the edge receptacle plated  23  corresponding thereto. On the other hand, number of longitudinal perforations  8  can be arbitrarily determined by number of pairs of the longitudinal roulette edges  20  and the edge receptacle plates  23 . Also, by placing some of a plurality of pairs of the longitudinal roulette edges  20  and the edge receptacle plates at positions not oppose to each other, a part of a plurality of pairs of the longitudinal roulette edges  20  and the edge receptacle plates  23  may be placed in opposition to each other to permit a selection of number of the longitudinal perforations  8  to be formed. 
     On the other hand, in the arbitrarily positioned longitudinal perforation forming apparatus  7 , as shown in FIG. 4, respective one bearings  19   a  and  22   a  of the first and second rotary shafts  19  and  22  may be supported by means of a mounting plate  18   a  which is detachable to one frame  18 . By removing the mounting plate  18   a  from the frame  18 , the bearings  19   a  and  22   a  can be released from one end portions of the first and second rotary shafts  19  and  22 . 
     By the construction set forth above, the longitudinal roulette edges  20  and the edge receptacle plates  23  can be exchanged and number of these can be increased and decreased with respect to the first and second rotary shafts  19  and  22 . 
     Next, construction and function of the arbitrarily positioned lateral perforation forming apparatus  9  will be discussed with reference to FIGS. 6 to  8 . In the drawings, the reference numerals  41  and  42  denote lateral roulette cylinder and receptacle cylinder across the traveling path of the continuous web paper  2 , respectively. 
     The lateral roulette cylinder  41  is supported on the frames  17  and  18  on both sides. A lateral roulette edge  43  is fixed in a groove provided at the predetermined position of the outer peripheral portion of the lateral roulette cylinder  41  in a condition slightly projecting the edge from the peripheral surface. 
     The receptacle cylinder  42  is supported on the frames  17  and  18  on both sides. On a part of the outer peripheral portion of the receptacle cylinder  42 , an edge receptacle portion  42   a  contacting with (or opposing to with a fine gap) the tip end of the lateral roulette edge  43  is provided in a projecting stepped form over a small angular range, e.g. 5 to 15° in the circumferential direction. When the lateral roulette edge  43  is placed in opposition to the edge receptacle portion  42   a , the lateral perforation  10  is formed in the continuous web paper  2  located therebetween. 
     Each supported portion of respective cylinders  41  and  42  on one frame  17  is extended outwardly from the frame  17 . On the shaft portions of the supported portions extended outwardly from the frame  17 , driven gears  44  and  45  having equal number of gear teeth are fixed at mutually axially offset positions, respectively. On the other hand, on the shaft portion of the receptacle cylinder  42 , an intermediate gear  46  meshing with the driven gear  44  of the lateral roulette cylinder  41  is rotatably supported, and the intermediate gear  46  has gear teeth of the number equal to that of the driven gear  44 . 
     A differential shaft  47  is supported on the frames  17  and  18  and an auxiliary frame  48  in the vicinity of the receptacle cylinder  42 . A first gear  49  meshing with the driven gear  45  of the receptacle cylinder  42  and a second gear  50  meshing with the intermediate gear  46  are supported on the differential shaft  47  via a differential mechanism  51 . Then, to the second gear  50 , an input gear  52  connected to a drive gear train G 3  for formation of lateral perforation is meshed, and the driven gear train G 3  is connected to a driving shaft S of the machine. To the differential shaft  47 , a servo motor  53  is connected. 
     As the differential mechanism  51 , the harmonic drive (tradename) may be employed, for example. The first and second gears  49  and  50  rotate integratedly in obedience to the rotation of the input gear  52 . During rotation, by rotation of the differential shaft  47 , rotation phases of the first and second gears  49  and  50  are shifted relative to each other to cause shifting of rotational phases of respective driven gears  44  and  45  of the lateral roulette cylinder  41  and the receptacle cylinder  42  relative to each other. 
     The harmonic drive used in the differential mechanism  51  is HDUD Type 2F. The construction of the harmonic drive as the differential mechanism is shown in FIG.  7 . In FIG. 7, the reference numeral  54  denotes a web generator,  55  denotes a flex spline,  56  denotes a circular spline,  57  denotes a dynamic spline,  58  denotes a web generator bearing,  59   a  and  59   b  denote flanges,  60  denotes a ball bearing. On the web generator  54 , an actuation shaft  47  is fixed. On one flange  59   a , the first gear  49  is fixed. On the other flange  59   b , the second gear  50  is fixed. 
     In the arbitrarily positioned lateral perforation forming apparatus  9 , respective driven gears  44  and  45  are driven to rotate by rotation of the input gear  52  via both gears  50  and  49  of the differential mechanism  51 , respectively. Then, the lateral roulette cylinder  41  and the receptacle cylinder  42  are driven to rotate at the same speed as the feeding speed of the continuous web paper  2  in the feed direction of the continuous web paper  2 . The rotational phase of the receptacle cylinder  42  relative to that of the lateral roulette cylinder  41  is varied by the differential mechanism  51 . The edge receptacle portion  42   a  is normally placed away from the lateral roulette edge  43  of the lateral roulette cylinder  41  as shown in FIG.  8 A. 
     In this condition, when the servo motor  53  is driven to rotate, the rotational phase of the first gear  49  is shifted relative to that of the second gear  50 . When a direction to cause phase shift is selected so that the rotational phase of the receptacle cylinder  42  is advanced relative to that of the lateral roulette cylinder  41 , for example, the edge receptacle portion  42   a  of the receptacle cylinder  42  is placed in opposition to the lateral roulette edge  43 , as shown in FIG.  8 B. By this, the lateral perforation  10  is formed in the continuous web paper  2 . By actuating the differential mechanism  51  in reverse direction, the edge receptacle portion  42   a  is again moved away from the lateral roulette edge  43  so that the lateral perforation is not formed thereafter. 
     The servo motor  32  of the arbitrarily positioned longitudinal perforation forming apparatus  7  and the servo motor  53  used in the arbitrarily positioned lateral perforation forming apparatus  9  are controlled of their rotation speed, number of rotation and direction of rotation by the control unit. Then, the mark  12  printed on the continuous web paper  2  is read by the mark sensor  11 . When the signal from the mark sensor  11  is input to the control unit, the servo motors  32  and  53  are driven in predetermined rotating directions at predetermined rotation speeds for predetermined number of turns after expiration of a predetermined period. 
     The receptacle cylinder  5  of the lateral perforation forming apparatus  1  for fold line, the input gear  26  of the arbitrarily positioned longitudinal perforation forming apparatus  7  and the input gear  52  of the arbitrarily positioned lateral perforation forming apparatus  9  are connected to the drive shaft S of the machine via respective drive gear trains (drive system) G 1 , G 2  and G 3 , to be driven in synchronism with traveling speed of the continuous web paper  2 , normally. 
     In both drive gear trains G 2  and G 3  for longitudinal perforation and lateral perforation, differential mechanisms  61  and  62  of the identical construction are interposed as shown in FIGS. 3 and 6. The differential mechanisms  61  and  62  have the same constructions as the differential mechanism  51  in the arbitrarily positioned lateral perforation forming apparatus  9 . Respective differential shafts  63  and  64  are respectively driven to rotate by servo motors  65  and  66  to cause variations of rotational phases of gears  69  and  70  on output side relative to gears  67  and  68  on input side to cause shiftings of rotational phases of respective pair of longitudinal roulette cylinder  15  of the arbitrarily positioned longitudinal perforation forming apparatus  7  and the receptacle cylinder  16 , and the lateral roulette cylinder  41  of the arbitrarily positioned lateral perforation forming apparatus  9  and the receptacle cylinder  42 , relative to the rotational phase according to the drive shaft S of the machine. Thus, position a of the longitudinal perforation  8  and the lateral perforation  10  in the longitudinal direction (traveling direction of the continuous web paper) is varied relative to the lateral perforation for fold line. In the shown embodiment, the gear  69  and the input gear  26  of the longitudinal perforation apparatus  7  are used in common. Speed, number and direction of rotation of servo motors  65  and  66  of the differential mechanism  61  and  62  interposed in respective gear trains G 2  and G 3  are adjusted manually. 
     Overall operation of the shown embodiment will be discussed hereinafter. 
     At first, the differential mechanisms  61  and  62  of the drive gear trains G 2  and G 3  respective of the arbitrarily positioned longitudinal perforation forming apparatus  7  and the arbitrarily positioned lateral perforation forming apparatus  9  are driven via push buttons  71  and  72 , drives  73  and  74  and their servo motors  65  and  66  as shown in FIG. 9 to manually adjust their rotation for setting a selected position a of the longitudinal perforation  8  and the lateral perforation  10  relative to the lateral perforation  3  for fold line. 
     The continuous web paper  2  is fed to travel in this condition. The continuous web paper  2  is formed with the lateral perforations for fold lines at a given interval by the lateral perforation forming apparatus  1  for fold line. Then, in the continuous web paper  2 , in sheet portions defined by the lateral perforations for fold line, at the most upstream side portion of the sheet portion in which the longitudinal perforation  8  and the lateral perforation  10  are to be formed, the mark  12  is printed preliminarily. 
     Then, when the mark  12  is read by the mark sensor  11 , measurement of traveling distance of the continuous web paper  2  according to signals from an encoder  75  mounted on the drive system of the machine is initiated by the control system shown in FIG. 10. A traveling distance from the mark sensor  12  to respective of perforation forming apparatus  7  and  9  are preliminarily set by a distance setting device  76 . Then, inputs from the encoder  75  and the distance setting device  76  are arithmetically processed by the control unit  77 . When the value of the signal from the encoder  75  becomes a set value, the servo motors  32  and  53  are driven to rotate in predetermined directions at predetermined rotation speeds for predetermined number of turns via drivers  78   a  and  78   b.    
     By rotating both servo motors  32  and  53 , the longitudinal perforation  8  having a length b starting from a position of a distance a from the lateral perforation  3  for fold line of the sheet portion where the mark  12  is placed is formed by the arbitrarily positioned longitudinal perforation forming apparatus  7 , as shown in FIG.  2 . 
     Next, by the arbitrarily positioned lateral perforation forming apparatus  9 , the lateral perforation  10  is formed at a position of distance a from the lateral perforation  3  for fold line. 
     After formation of the arbitrarily positioned perforations  8  and  10 , respectively, the servo motors  32  and  53  are rotated respectively at the same rotation speed for the same number of turns in the reverse direction to cause phase shift of the edge receptacle portions relative to respective roulette edges so that perforations are not formed any more. 
     Thus, by detecting presence or absence of mark  12  per each sheet portion, both perforations are formed at respectively selected positions only for the sheet portion, on which the mark  12  is preliminarily printed. 
     It should be noted that the positions of respective perforations may be determined from the mark  12  instead of the lateral perforation  3  for fold line. 
     In the shown embodiment, the embodiment employing both of the arbitrarily positioned longitudinal perforation forming apparatus  7  and the arbitrarily positioned lateral perforation forming apparatus  9  has been illustrated, it is possible to employ only arbitrarily positioned lateral perforation forming apparatus  9  as required. 
     In the shown embodiment, by sequentially arranging the arbitrarily positioned longitudinal perforation forming apparatus  7  and the arbitrarily positioned lateral perforation forming apparatus  9  in the traveling direction of the continuous web paper  2 , the perforation in the longitudinal direction and the perforation in the lateral direction can be provided at selected positions in addition to the perforation for fold line, in the continuous web paper  2 . For example, it is possible to form a portion surrounded by perforations. Therefore, wide variation can be provided for specifications of processing of printing products. 
     Although the present invention has been illustrated and described with respect to exemplary embodiment which is to be applied for the form printing machine or applicable for forming lateral perforation, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions may be made therein and thereto, without departing from the spirit and scope of the present invention. Therefore, the present invention should not be understood as limited to the specific embodiment set out above but to include all possible embodiments which can be embodied within a scope encompassed and equivalents thereof with respect to the feature set out in the appended claims.
An arbitrarily positioned lateral perforation forming apparatus can form a lateral perforation at an arbitrary position or selected position in a continuous web paper at high precision by a simple control system with small control amount. A lateral roulette cylinder projecting a lateral roulette edge on its outer periphery, arranged on one side of the continuous web paper and rotating in a traveling direction of the continuous web paper; and a receptacle cylinder projecting an edge projecting portion opposing to the lateral roulette edge of the lateral roulette cylinder on its outer periphery, arranged on the other side of the continuous web paper, rotating in the traveling direction of the continuous web paper, and forming a lateral perforation in the continuous web paper when the edge receptacle portion opposes the roulette edge; are rotated in synchronism with traveling of the continuous web paper in the drive system. Furthermore, the arbitrarily positioned lateral-perforation forming apparatus includes a first differential mechanism disposed in an element connected to one of the lateral roulette cylinder and the receptacle cylinder in the drive system, causing difference in rotational phases of the lateral roulette cylinder and the receptacle cylinder by varying rotation of a differential shaft thereof for selectively placing the edge receptacle portion at a position opposing to the roulette edge and a position circumferentially offsetting from the roulette edge, and a first control unit for controlling rotation of the differential shaft of the first differential mechanism.