Abstract:
A web joining apparatus and related method. The apparatus includes a turret arm which supports an old roll and a new roll around which band-state flexible support bodies are wound, a front pasting drum including a holding device holding the tip end of the band-state flexible support body of the new roll and a cutting drum provided with a cutting member with substantially the same length as the width of the band-state flexible support body. A projection amount is set so that only a single sheet of the band-state flexible support body can be cut off. The flexible support body of the old roll is cut off and the tail end of the flexible support body of the old roll and the tip end of the flexible support body of the new roll are joined as the band-state flexible support body is conveyed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a web joining apparatus and a method and particularly to a web joining apparatus and a method for joining a thin-plate band-state material such as plastic, paper, metal foil, etc. (hereinafter referred to as “web”) in the state where ends of a new and an old rolls are overlapped with each other. 
     2. Description of the Related Art 
     A conventional web joining apparatus in general is an apparatus of a so-called face-to-face joining type by which a tail end of an old web and a tip end of a new web is abutted to each other at joining and joined in that state by pasting them through extension of a joining tape to the both (See Japanese Examined Application Publication No. 48-38461, for example). This type of apparatus has a long history of operation and is still in use after repeated improvements (See Japanese Patent Application Laid-Open No. 6-171806, for example). 
     The face-to-face web joining apparatus described in this Japanese Patent Application Laid-Open No. 6-171806 is a three-drum type apparatus comprising a cutting drum provided with a cutting blade and a member for withdrawing a web tip end of a new roll and capable of rotation at the same speed as a conveying speed of the web, a cutting/joining drum capable of rotation at the same speed as the conveying speed of the web, and a joining drum detachably holding a joining tape and capable of rotation at the same speed as the conveying speed of the web, wherein the webs are cut off and joined while the tail end of the old roll and the tip end of the new roll are held at each of the drums so that the webs can be cut and joined at a high speed. 
     However, in the conventional face-to-face web joining apparatus, there is a problem that it is not suitable for a process requiring high cleanliness (degree of cleanness) (such as a manufacturing process of a functional film used in a liquid crystal display device). 
     Specifically, in the apparatus of the above Japanese Patent Application Laid-Open No. 6-171806, for example, a guide member with a triangular section for guiding the web at joining so that it does not deviate from a web conveying path is provided in a space portion in the substantially triangular shape surrounded by rotating outer circumferences of the cutting drum, the cutting/joining drum and the joining drum. But this guide member is rubbed by the web, which often generates contamination such as dusts. 
     Moreover, the old roll web is rubbed by the new roll web, which generates contamination such as dusts in many cases. 
     However, if a measure is to be taken against these problems, it is difficult to exclude the guide member and the like from the viewpoint of the principle of face-to-face abutting of the webs, and it is also difficult to employ a construction to prevent rubbing between the old roll web and the new roll web, for which improvement by other devices has been in demand. 
     The present invention was made in view of these circumstances, and its object is to provide a web joining apparatus and a method which can improve joining accuracy without generating contamination such as dusts so as to be applied to a process requiring high cleanliness (degree of cleanness) and can improve web quality. 
     SUMMARY OF THE INVENTION 
     The present invention provides, in order to achieve the above object, a web joining method in which, while a band-state flexible support body wound around an old roll is made to run, the band-state flexible support body of the old roll is cut off and the vicinity of a tail end of the band-state flexible support body of the old roll and a tip end of a band-state flexible support body wound around a new roll are joined to each other, comprising the steps of: 
     holding the tip end of the band-state flexible support body of the new roll at a front side drum; 
     holding a back pasting joining tape at a back pasting drum; 
     overlapping the tail end of the band-state flexible support body of the old roll and the tip end of the band-state flexible support body of the new roll with each other while the front-side drum is rotated at the same speed as a conveying speed of the band-state flexible support body; 
     cutting off the band-state flexible support body of the old roll after overlapping; 
     discarding an upstream portion in the conveying direction of the cut-off band-state flexible support body of the old roll; and 
     joining through the back pasting joining tape a downstream portion in the conveying direction of the band-state flexible support body of the cut-off old roll to the tip end of the band-state flexible support body of the new roll while the back pasting drum is rotated at the same speed as the conveying speed of the band-state flexible support body. 
     According to the present invention, differently from the so-called face-to-face joining method in which the tail end of the old web and the tip end of the new web are abutted to each other at web joining and they are joined by pasting through extension of a joining tape over the both, a so-called overlapping joining method is employed in which the tip end of the new web held on the front-side drum is overlapped with the vicinity of the tail end of the old web on the front-side drum and then, only the old web is cut off after overlapping and the upstream portion of the old web is fed backward to be discarded substantially at the same time and after that, the tail end of the old web and the tip end of the new web are joined to each other through a back pasting joining tape. 
     According to such an overlapping joining method, a guide member is not needed for guiding the web at the joining to prevent the web from deviating from the conveying path, and such nonconformity is not caused that the guide member is rubbed with the web to generate contamination such as dusts. 
     Also, since the upstream portion of the old web is fed backward to be discarded substantially at the same time with the cutting of the old web, nonconformity of generation of contamination such as dusts due to rubbing between the old web and the new web is not caused, either. 
     Therefore, contamination such as dusts is not caused so as to be applied to a process requiring high cleanliness (degree of cleanness), the joining accuracy can be improved, and the web quality can be improved. 
     Moreover, the present invention provides a web joining apparatus, comprising: 
     a turret arm which supports an old roll and a new roll around which band-state flexible support bodies are wound capable of drawing and is rotatable per predetermined angle; 
     a front pasting drum provided with a holding device which holds the tip end of the band-state flexible support body of the new roll to which a double-sided joining tape is pasted on the back side of the tip end and capable of rotation at the same speed as the conveying speed of the band-state flexible support body at the joining of the band-state flexible support body; and 
     a cutting drum provided with a cutting member with substantially the same length as the width of the band-state flexible support body, the cutting member being provided on circumferential surface and in which a projection amount from the circumferential surface is set so that only a single sheet of the band-state flexible support body can be cut off, the cutting drum being capable of rotation at the same speed as the conveying speed of the band-state flexible support body at the cutting of the band-state flexible support body, 
     wherein the band-state flexible support body of the old roll is cut off and the tail end of the band-state flexible support body of the old roll and the tip end of the band-state flexible support body of the new roll are joined to each other while the band-state flexible support body is being conveyed. 
     According to the present invention, differently from the so-called face-to-face joining method in which the tail end of the old web and the tip end of the new web are abutted to each other at web joining and they are joined by pasting through extension of a joining tape over the both, a so-called overlapping joining method is employed in which the tip end of the new web and the vicinity of the tail end of the old web to which the double-sided joining tape is pasted in advance are joined to each other through the double-sided joining tape and only the old web after joining is cut off substantially at the same time. 
     According to such an overlapping joining method, various effects as above can be obtained. Particularly, in this apparatus, differently from the conventional three-drum (or four-drum) method, a two-drum method having a front pasting drum and a cutting drum can be employed, which can simplify the apparatus construction. 
     Moreover, the present invention provides a web joining method in which, while a band-state flexible support body wound around an old roll is made to run, the band-state flexible support body of the old roll is cut off and the vicinity of a tail end of the band-state flexible support body of the old roll and a tip end of a band-state flexible support body wound around a new roll are joined to each other, comprising the steps of: 
     holding at the front pasting drum the tip end of the band-state flexible support body of the new roll to which a front pasting joining tape is pasted on the front side of the tip end; 
     holding a back pasting joining tape at a back pasting drum; 
     joining the tail end of the band-state flexible support body of the old roll and the tip end of the band-state flexible support body of the new roll to each other through the front pasting joining tape while the front pasting drum is rotated at the same speed as the conveying speed of the band-state flexible support body; 
     cutting off the band-state flexible support body of the old roll after joining; 
     discarding an upstream portion in the conveying direction of the cut-off band-state flexible support body of the old roll; and 
     joining a downstream portion in the conveying direction of the cut-off band-state flexible support body of the old roll and the tip end of the band-state flexible support body of the new roll to each other through the back pasting joining tape while the back pasting drum is rotated at the same speed as the conveying speed of the band-state flexible support body. 
     Also, for that purpose, a web joining apparatus is provided comprising: 
     a turret arm which supports an old roll and a new roll around which band-state flexible support bodies are wound capable of drawing and is rotatable per predetermined angle; 
     a front pasting drum provided with a holding device which holds the tip end of the band-state flexible support body of the new roll to which a front pasting joining tape is pasted on the front side of the tip end and capable of rotation at the same speed as the conveying speed of the band-state flexible support body at the joining of the band-state flexible support body; 
     a back pasting drum provided with a holding device which holds the back pasting joining tape capable of peeling and capable of rotation at the same speed as the conveying speed of the band-state flexible support body at the joining of the band-state flexible support body; and 
     a cutting drum provided with a cutting member with substantially the same length as the width of the band-state flexible support body, the cutting member being provided on circumferential surface and in which a projection amount from the circumferential surface is set so that only a single sheet of the band-state flexible support body can be cut off, the cutting drum being capable of rotation at the same speed as the conveying speed of the band-state flexible support body at the cutting of the band-state flexible support body, 
     wherein the band-state flexible support body of the old roll is cut off and the tail end of the band-state flexible support body of the old roll and the tip end of the band-state flexible support body of the new roll are joined to each other while the band-state flexible support body is being conveyed. 
     In the web joining apparatus of the present invention, it is preferable to provide a backward feeding device which withdraws the band-state flexible support body of the old roll in the direction opposite to the conveying direction so that the band-state flexible support body is withdrawn in the direction opposite to the conveying direction substantially at the same time as cutting-off of the band-state flexible support body of the old roll. 
     According to the present invention, differently from the so-called face to face joining method in which the tail end of the old web and the tip end of the new web are abutted to each other at web joining and they are joined by pasting through extension of a joining tape over the both, a so-called overlapping joining method is employed in which the tip end of the new web to which the front pasting joining tape is pasted in advance and the vicinity of the tail end of the old web are joined to each other through the front pasting joining tape and then, only the old web is cut off after joining, and the upstream portion of the old web is fed backward and discarded substantially at the same time and after that, the joined opposite surfaces are joined through the back pasting joining tape. 
     According to such an overlapping joining method, a guide member is not needed for guiding the web at the joining to prevent the web from deviating from the conveying path, and such nonconformity is not caused that the guide member is rubbed with the web to generate contamination such as dusts. 
     Also, since the upstream portion of the old web is fed backward to be discarded substantially at the same time with the cutting-off of the old web, nonconformity of generation of contamination such as dusts due to rubbing between the old web and the new web is not caused, either. 
     Therefore, contamination such as dusts is not caused so as to be applied to a process requiring high cleanliness (degree of cleanness), the joining accuracy can be improved, and the web quality can be improved. 
     In the present invention, it is preferable to provide steps of: 
     pasting a double-sided joining tape on the back side of the tip end of the band-state flexible support body of the new roll; and 
     joining the vicinity of the tail end of the band-state flexible support body of the old roll and the tip end of the band-state flexible support body of the new roll to each other through the double-sided joining tape at joining of the vicinity of the tail end of the band-state flexible support body of the old roll and the tip end of the band-state flexible support body of the new roll to each other through the front pasting joining tape. 
     In this way, by joining the vicinity of the tail end of an old web and the tip end of a new web to each other through the double-sided joining tape before joining through the back pasting joining tape, the overlapping joining can be performed more surely. 
     Moreover, the present invention provides, in order to achieve the purpose, a web joining method in which, while a band-state flexible support body wound around an old roll is made to run, the band-state flexible support body of the old roll is cut off and the vicinity of a tail end of the band-state flexible support body of the old roll and a tip end of a band-state flexible support body wound around a new roll are joined to each other, comprising the steps of: 
     holding at the front pasting drum the tip end of the band-state flexible support body of the new roll to which a front pasting joining tape is pasted on the front side of the tip end; 
     joining the tail end of the band-state flexible support body of the old roll and the tip end of the band-state flexible support body of the new roll to each other through the front pasting joining tape while the front pasting drum is rotated at the same speed as the conveying speed of the band-state flexible support body; 
     cutting off the band-state flexible support body of the old roll after joining; and 
     discarding an upstream portion in the conveying direction of the cut-off band-state flexible support body of the old roll. 
     According to the present invention, since a back pasting drum as in the above-mentioned joining method and apparatus is not needed but the webs can be joined in the 2-drum construction with the front pasting drum and the cutting drum, the apparatus construction can be advantageously simplified. 
     Moreover, the present invention provides, in order to achieve the purpose, a web joining method in which, while a band-state flexible support body wound around an old roll is made to run, the band-state flexible support body of the old roll is cut off and the vicinity of a tail end of the band-state flexible support body of the old roll and a tip end of a band-state flexible support body wound around a new roll are joined to each other, comprising the steps of: 
     holding at the front pasting drum the tip end of the band-state flexible support body of the new roll to which a double-sided joining tape is pasted on the back side of the tip end; 
     joining the tail end of the band-state flexible support body of the old roll and the tip end of the band-state flexible support body of the new roll to each other through the double-sided joining tape while the front pasting drum is rotated at the same speed as the conveying speed of the band-state flexible support body; 
     cutting off the band-state flexible support body of the old roll after joining; and 
     discarding an upstream portion in the conveying direction of the cut-off band-state flexible support body of the old roll. 
     According to the present invention, since a back pasting drum as in the above-mentioned joining method and apparatus is not needed but the webs can be joined in the 2-drum construction with the front pasting drum and the cutting drum, the apparatus construction can be advantageously simplified. 
     As mentioned above, according to the present invention, since contamination such as dusts is not caused, the invention can be applied to a process requiring high cleanliness (degree of cleanness), the joining accuracy can be improved and the web quality can be improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a web joining apparatus of the present invention; 
         FIG. 2  is a structural diagram of a web joining unit; 
         FIGS. 3A and 3B  are operation explanatory diagrams of the web joining unit; 
         FIGS. 4A and 4B  are operation explanatory diagrams of the web joining unit; 
         FIG. 5  is an operation explanatory diagram of the web joining unit; 
         FIGS. 6A and 6B  are operation explanatory diagrams of the web joining unit; 
         FIGS. 7A and 7B  are operation explanatory diagrams of the web joining unit; 
         FIGS. 8A and 8B  are operation explanatory diagrams of the web joining unit; 
         FIG. 9  is an operation explanatory diagram of the web joining unit; 
         FIGS. 10A and 10B  are operation explanatory diagrams of the web joining unit of another embodiment; and 
         FIGS. 11A and 11B  are operation explanatory diagrams of the web joining unit of another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment (first embodiment) of a web joining apparatus and a method according to the present invention will be described below in detail referring to the attached drawings.  FIG. 1  is an entire diagram of a web joining apparatus  10  according to the embodiment of the present invention. As shown in  FIG. 1 , the web joining apparatus  10  comprises a turret device  12  as a turret device, a web joining unit  14  as a joining device, and a web conveying device  16  as a conveying device. 
     The turret device  12  has a turret arm  18 , and this turret arm  18  is provided rotatably at a support column  20  with a shaft  22  as the fulcrum. At one end of this turret arm  18 , an old roll  24  in which rewinding of the web is to end is rotatably supported by a shaft  26 , while at the other end, a new roll  28  in which drawing of the web is to start is rotatably supported by a shaft  30 . A web  32  is drawn from the old roll  24 . This web  32  is in rotating contact with guide rollers  34 ,  36  and guided to the web joining unit  14 . 
     The shaft  26  and the shaft  30  of the turret device  12  are provided with a clutch device (not shown) so that they can be instantaneously switched to the direction opposite to the web drawing direction. 
     The web joining unit  14  comprises, as shown in  FIG. 2 , a front pasting drum  38 , a back pasting drum  40  and a cutting drum  42 , and each of them is installed at a machine frame  43 . These drums  38 ,  40 ,  42  are rotated in synchronization by power from a driving motor, not shown. The web  32  is inserted between the front pasting drum  38  and the back pasting drum  40  as well as the cutting drum  42  and wound by a winding device, not shown. 
     The tip end of a web  44  from the new roll  28  is conveyed by the web conveying device  16  (See  FIG. 1 ), which will be described later, to the position of the web joining unit  14  from the position of the new roll  28 , and then, it is attracted by an attracting plate  41  as shown in  FIG. 2  and waits ready for joining. The attracting plate  41  is movable to be moved as shown by an arrow  41 A in  FIG. 3 , which will be described later, so that the tip end of the web  44  can be supplied to the front pasting drum  38 . 
     To the tip end of the web  44  attracted by the attracting plate  41 , a front pasting joining tape  62  is supplied and pasted by a front pasting tape supply device, not shown. 
     In  FIG. 2 , a cutter  46  is mounted at the cutting drum  42 . This cutter  46  is to cut of only the web  32  in the state where the web  32  is overlapped with the web  44  wound and held by the front pasting drum  38  as shown in  FIG. 6 , which will be described later. Therefore, a projection amount of the tip end of the cutter  46  from the cutting drum  42  is preferably set substantially equal to the thickness of the web  32 . 
     On the flat potion on the surface of the front pasting drum  38 , vent holes  50  are formed, and these vent holes  50  communicate with a vent hole  54  formed at a rotary hollow shaft  52 . To the rotary hollow shaft  52 , an air intake device and an air supply device, not shown, are connected. When the air intake device is driven, the vicinity of the tip end of the web  44  is attracted and held by the vent holes  50 , as shown in  FIG. 4 , which will be described later, while when the air supply device is driven, cutting chips of the web  44  are removed from the front pasting drum  38  at the position shown in  FIG. 9 , which will be described later. 
     The back pasting drum  40  has an attracting disk  40 B for detachably attracting the back face of the back pasting joining tape  47  substantially at the center of its outer circumference part and is linked to an attracting device, not shown, through a hollow shaft portion  40 C. Also, guide rollers  40 E,  40 F are mounted to the back pasting drum  40  for supporting the web (old web  32 ) between the old roll  28  and a pass roller  37 . 
     This web joining unit  14  is controlled to be driven when the tail end of the web  32  from the old roll  24  comes close to the web joining unit  14 . The details will be described later. 
     The above-mentioned web conveying device  16  is comprised by, as shown in  FIG. 1 , a revolving device of endless chains  66 ,  66  (one of chains is not shown) as a moving device and a holding member  68  connected to these chains  66 ,  66 . The chains  66 ,  66  are placed with an interval wider than the width of the web  44  and revolved/moved in the direction shown by an arrow in the figure through a plurality of sprockets  70  within a range from a lower position of the new roll  28  to a joining position of the joining unit  14 . Reference numeral  71  designates a driving sprocket for the chain  66 , and this sprocket  71  is mounted to the machine frame  43 . 
     The holding member  68  is comprised by two lengthy plates. These plates are both formed wider than the width of the web  32  so that the entire width of the tip end of the web  32  can be held over the entire area. 
     Next, the web joining method by the web joining device  10  constructed as above will be sequentially described referring to  FIGS. 1 to 9 . 
     First, in  FIG. 1 , the chains  66 ,  66  of the conveying device  16  are revolved/moved to position the holding member  68  at the lower position of the new roll  28  as shown. Then, a tip end  44 A of the web  44  of the new roll  28  is drawn from the new roll  28  by a predetermined amount. Then, the entire width of the web  44  is held by the two plates of the holding member  68  over the entire area. By this, conveying preparation work of the web  44  is completed. 
     Then, the chains  66 ,  66  are revolved/moved to move the holding member  68 . By this, the web  44  is drawn from the new roll  28 , and when the tip end  44 A of the web  44  is positioned at the joining position of the joining unit  14 , that is, the position shown in  FIG. 2 , the movement is stopped. And the tip end  44 A of the web  44  is attracted by the attracting plate  41 . 
     Then, at the position shown in  FIG. 2 , the front pasting joining tape  62  is supplied and pasted by a front pasting tape supply device, not shown, to the tip end  44 A of the web  44  attracted by the attracting plate  41 . At this time, supply is performed so that the lower half of the entire width (vertical width) of the front pasting joining tape  62  shown in the figure is pasted to the tip end  44 A of the web  44 , while the upper half is left free (not pasted). 
     Then, as shown in  FIG. 3A , the front pasting drum  38  is rotationally moved in the counterclockwise direction by 90 degrees, the attracting plate  41  is moved as shown by an arrow  41 A, and the tip end  44 A of the web  44  is supplied to the front pasting drum  38 . At the same time, the vent holes  50  (See  FIG. 2 ) are made to communicate with the air intake device, not shown, by which the web  44  to which the front pasting joining tape  62  is pasted at the tip end  44 A is attracted and held as shown in the partial enlarged diagram in  FIG. 3B . 
     Then, as shown in  FIG. 4A , the front pasting drum  38  is rotationally moved in the counterclockwise direction by 270 degrees and kept stationary in that state.  FIG. 4B  is the partial enlarged diagram showing the tip end  44 A of the web  44  in this state. 
     Also, as shown in  FIG. 4A , the back pasting joining tape  47  is supplied by a back pasting tape supply device, not shown, to the position of the attracting disk  40 B of the back pasting drum  40 . At this time, the supply is performed so that the adhesive surface of the back pasting joining tape  47  comes to the outside (the side opposite to the surface in contact with the back pasting drum  40 ). And by making the attracting disk  40 B communicate with the attracting device, not shown, the back pasting joining tape  47  is attracted and held by the attracting disk  40 B. 
     Then, the front pasting drum  38  is rotationally moved in the direction opposite to the arrow direction shown in  FIG. 4  (the clockwise direction), and the back pasting drum  40  and the cutting drum  42  are rotationally moved in the arrow direction (counterclockwise direction) in synchronization with that. The circumferential velocity of these drums  38 ,  40 ,  42  is set up so as to become the same as the conveying speed of the web  32  at the time of joining.  FIG. 5  shows the state where this rotational moving operation progresses. 
     When the respective drums  38 ,  40 ,  42  are further moved rotationally, the state shown in  FIG. 6A  is brought about. In this state, the cutter  46  of the cutting drum  42  cuts off only the web  32  while the web  32  is overlapped over the web  44  wound and held around the front pasting drum  38 . The enlarged diagram of this state is shown in  FIG. 6B . 
     In  FIG. 6B , on the downstream side (right side) of the cut-off part, the front pasting joining tape  62  is pasted to the web  32 , and the web  32  and the web  44  are in the overlapping joined state on one side (front side). 
     By further rotationally moving the respective drums  38 ,  40 ,  42  and instantaneously rotating backward the shaft  26  of the turret device  12  in  FIG. 1  through switching of the clutch device (not shown), the left side part (cutting chips  32 A of the web  32 ) of the cut-off web  32  is rewound in the arrow direction and removed from the web joining unit  14  as shown in  FIG. 7A . The enlarged diagram of the overlapping joined part in this state is shown in  FIG. 7B . 
     As shown in  FIG. 8A , when the respective drums  38 ,  40 ,  42  are further rotationally moved, the back pasting joining tape  47  attracted and held by the attracting disk  40 B of the back pasting drum  40  is pasted while extending over the overlapping joined part between the web  32  and the web  44 . The enlarged diagram of the overlapping joined part in this state is shown in  FIG. 8B . That is, the overlapping joined part of the web  32  and the web  44  is joined through the front pasting joining tape  62  and the back pasting joining tape  47  from both sides of front and back. 
     When the respective drums  38 ,  40 ,  42  are further rotationally moved, the respective drums  38 ,  40 ,  42  are moved, and at the same time, in the turret device  12  in  FIG. 1 , the shaft  30  of the new roll  28  is rotated/driven, the drawing of the web  44  is started and the web  44  is conveyed in the arrow direction. 
     When the respective drums  38 ,  40 ,  42  are further rotationally moved, the respective drums  38 ,  40 ,  42  are moved, and the winding state of the web  44  around the front pasting drum  38  is released. 
     When the respective drums  38 ,  40 ,  42  are further rotationally moved, the respective drums  38 ,  40 ,  42  are moved to the positions shown in  FIG. 9 , and the winding state of the web  44  on the circumferential surface of the back pasting drum  40  is released. However, since the upward left movement of the web  44  is restricted by the guide roller  40 F of the back pasting drum  40 , no such nonconformity occurs that the web  44  contacts the cutting drum  42 . 
     When the respective drums  38 ,  40 ,  42  are further rotationally moved, the respective drums  38 ,  40 ,  42  are moved, and the winding state of the web  44  onto the guide roller  40 F of the back pasting drum  40  is released. However, since the cutting drum  42  is rotationally moved in the direction where the cutter  46  of the cutting drum  42  gets away from the web  44 , no such nonconformity occurs that the web  44  contacts the cutting drum  42 . And the respective drums  38 ,  40 ,  42  are further rotationally moved, and the rotational movement is stopped in the initial state shown in  FIG. 2 . 
     According to the above described embodiment of the present invention, a guide member which guides so that the web does not deviate from the web conveying path at the joining is not needed, and no such nonconformity occurs that the guiding member rubs with the web to generate contamination such as dusts. Also, there is no such nonconformity that the guide member rubs with the web to generate a scratch on the web. 
     Also, since the upstream portion of the old web  32  (cutting chip  32 A) is fed backward and discarded substantially at the same time as cutting-off of the old web  32 , there is no such nonconformity that the old web  32  rubs with the new web  44  to generate contamination such as dusts. 
     Therefore, contamination such as dusts is not caused so as to be applied to a process requiring high cleanliness (degree of cleanness), the joining accuracy can be improved, and the web quality can be improved. 
     Next, another embodiment (second embodiment) of the present invention will be described referring to  FIGS. 10 and 11 . For the same or similar members as those in the first embodiment shown in  FIGS. 1 to 9 , the same reference numerals are given and their detailed description will be omitted. 
     In this embodiment, in place of the front pasting joining tape  62  in the first embodiment, a double-sided joining tape  63  is employed.  FIG. 10  shows a state where the attracting plate  41  is moved as shown by the arrow  41 A, the tip end  44 A of the web  44  is supplied to the front pasting drum  38 , and at the same time, the vent holes  50  (See  FIG. 2 ) are made to communicate with the air intake device, not shown. By this, the web  44  to which the double-sided joining tape  63  is pasted at the tip end  44 A is attracted and held as shown in the partial enlarged diagram in  FIG. 10B , which corresponds to  FIG. 3  of the first embodiment. 
     That is, as shown in  FIG. 10B , the double-sided joining tape  63  is pasted on the back face of the tip end  44 A of the web  44  by the double-sided tape supply device, not shown. 
       FIG. 11  shows a state where the double-sided joining tape  63  is pasted to the web  32 , and from the state where the web  32  and the web  44  are in the overlapping joined state, the left portion of the cut-off web  32  (cutting chips  32 A of the web  32 ) is rewound in the arrow direction and removed from the web joining unit  14 , which corresponds to  FIG. 7  of the first embodiment. 
     As shown in the partial enlarged diagram in  FIG. 11B , the back face of the web  44  and the front face of the web  32  are joined to each other with the double-sided joining tape  63 . 
     Moreover, the respective drums  38 ,  40 ,  42  are rotationally moved, and the back pasting joining tape  47  attracted and held by the attracting disk  40 B of the back pasting drum  40  is pasted in the state extending over the overlapping joined part between the web  32  and the web  44 . 
     In this state, the back face of the web  44  and the front face of the web  32  are in the joined state with the double-sided joining tape  63 , and the back face of the web  44  and the back face of the web  32  are in the overlapping joined state with the back pasting joining tape  47 . 
     According to the above described second embodiment of the present invention, the web  32  and the web  44  are joined together with the double-sided joining tape  63  in addition to the first embodiment, and the overlapping joining is further ensured. 
     Embodiments of the web joining device and the methods according to the present invention have been described above, but the present invention is not limited to the above embodiments but various modes can be employed. 
     For example, in this embodiment, the back face of the web  44  and the front face of the web  32  are joined by the double-sided joining tape  63 , but in place of the construction of supplying the double-sided joining tape  63  to the back face of the web  44 , a construction that an adhesive is applied on the back face of the web  44  can be employed, which gives substantially the same effects as those of this embodiment. 
     Also, the above embodiment is in the 3-drum construction of the front pasting drum  38 , the back pasting drum  40  and the cutting drum  42 , but as already mentioned, it may be the 2-drum construction without the back pasting drum  40 , which gives substantially the same effects as those of this embodiment. 
     Moreover, the above embodiment is in the construction in which the shaft  26  and the shaft  30  of the turret device  12  are driven automatically, but instead of that, a manual type off-line setup station may be employed. 
     Furthermore, a nip device and the like may be arranged at the downstream side of the web joining device of the present invention as appropriate. By arranging such a nip device and the like, joining is further ensured.