Abstract:
A cutter device for use in a printer in which a broad continuous printing sheet is printed and thereafter the printed portion of the sheet is cut along a width direction to be dropped downward to a tray. The cutter devise includes a cutter which reciprocating to cut the printed sheet in the width direction; and holding member for holding the sheet to prevent the sheet from dropping on a cutting start side of the cutter. The sheet is released from the holding member substantially in synchronism with the completion of the cutting by the cutter. Preferably, the sheet is fed a reverse in rewinding direction before the cutter finishes cutting to return to its original position, so that the cut end of a non-printed sheet is prevented from interfering with the returning cutter. The compactness of the cutter device is achieved and the sheet charging operations are facilitated.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a cutter device in which after a broad continuous printing sheet drawn from a horizontally placed roll is printed, the printed sheet is cut with a reciprocating cutter. 
     2. Description of the Related Art 
     In a case where a continuous printing sheet drawn from a horizontally placed roll is printed and subsequently cut with a reciprocating cutter, the printed sheet cannot be cut clear if it moves. Moreover, when a broad sheet is used, a cut portion hangs down by the sheet&#39;s own weight during the cutting operation and an uncut portion is wrinkled or surged. 
     Therefore, since the sheet cannot be cut straight, a cut edge is curved, or the sheet may be torn at the vicinity of a terminal end of the cut edge. To solve the problem, a conventional printer is provided with a press bar for pressing the printing sheet over the entire width of the printing sheet, and the press bar is pressed against the sheet to fix the sheet immediately before the sheet is cut with the cutter. 
     In the conventional device, however, since the press bar usually transverses the entire width above the sheet, the device is large-sized including its operation mechanism. Especially, when the sheet has a large width, not only the press bar should be lengthened, but also the weight of the printed sheet must be increased, so that it is difficult to press the sheet uniformly over the entire length. Moreover, when the sheet is set, a front edge of the sheet has to be passed through a small gap under the press bar, and sheet charging operation is also laborious. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished in consideration of circumstances described above, and an object thereof is to provide a cutter device which can achieve compactness to facilitate the sheet charging operation and which is suitable especially for a printer using a broad sheet. 
     To attain this and other objects, the present invention provides a cutter device for use in a printer in which a broad continuous printing sheet drawn from a horizontally placed roll is printed and the printed sheet is cut along its width direction, dropped downward and received by a tray. The cutter device is provided with a cutter which reciprocates to cut the printed sheet in its width direction, holding means interposed between the cutter and the tray for holding the sheet to prevent the sheet from dropping in the vicinity of a cutting start side of the cutter, and a controller for allowing the holding means to hold a cutting start end of the printing sheet substantially in synchronism with start of cutting by the cutter and for detaching the holding means from the printing sheet substantially synchronously with completion of the cutting by the cutter. 
     The holding means is provided with a guide plate for guiding the cut printing sheet to the tray, and a pressing member for pressing the printing sheet on a top surface in the vicinity of the cutting start side of the cutter against the guide plate. The controller allows the pressing member to press the printed sheet substantially synchronously with the start of the cutting by the cutter and hold the printing sheet between the pressing member and the guide plate, and detaches the pressing member from the printed sheet substantially synchronously with the completion of the cutting by the cutter. 
     Here, the controller preferably prevents the cutter from abutting on a cut edge of the sheet by feeding in reverse the printing sheet by a predetermined amount in the rewinding direction before the cutter finishes cutting to return to its original position. Moreover, the cutter includes a rotating blade which rotates at a high speed, and has a good sharpness, so that the entire width of the sheet can be cut at once at a high speed. The cutter preferably moves at a speed of about 0.5 to 2.0 m/sec. If cutting is performed at a high speed, by using the inertia of the sheet and the frictional resistance between the sheet and the guide member during cutting, cutting can be completed before the load of the sheet applied to the pressing member increases. Thus, the pressing force of the pressing member can be reduced. 
     After printing is completed, the sheet is fed by the predetermined amount to align a cutting position with a cutter position. Upon receipt of a cutting command, the controller presses the pressing member on the sheet to press an end of the printed sheet on the cutting start side. Substantially simultaneously or slightly late the cutter starts cutting the sheet, and moves at a high speed. 
     The controller detaches the pressing member from the sheet substantially synchronously with a time at which the cutter finishes cutting the sheet. Therefore, the entire width of the cut edge of the printed sheet starts dropping substantially simultaneously. Consequently, the edge cut by the cutter can be straight and clear without being curved. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view diagrammatically showing a printer employing a cutter device according to an embodiment of the present invention; 
     FIG. 2 is a perspective view illustrating an inner arrangement of main parts of the printer of the embodiment; 
     FIG. 3 is a schematic diagram showing the cutter device of the embodiment of FIG. 1; 
     FIG. 4 is a front view of a cutter of the cutter device of FIG. 3; 
     FIG. 5 is a sectional view taken along line V—V of FIG. 4; 
     FIGS. 6A and 6B are descriptive diagrams showing the operation of a pressing lever of the cutter device, FIG. 6A showing a released sheet state and FIG. 6B showing a held sheet state; and 
     FIG. 7 is a timing chart of the entire operation of the cutter device. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In FIG. 1, a reference numeral  10  denotes a printer unit which is housed in a longitudinal case  12 , and a top surface of the case  12  forms a lid  14  which is able to be opened upward. The case  12  is supported by a pair of opposite legs  16 . A roll  20  with a printing sheet  18  wound therearound is held horizontally in width direction of the case  12  at the back downside of the case  12 . The printing sheet  18  is guided from the roll  20  into the case  12 , and printed in the case  12 . The printing sheet  18  is used as a poster or the like, its width is broad, and the maximum width of about 54 inches is used. 
     The printing sheet  18  is guided by a guide roller  22  to a gap between a pair of upper and lower guide plates  24  and  26 , further held between a pair of upper and lower feed rollers  28  and  30 , and fed toward a front face of the case  12 . While the printing sheet  18  is rested on a platen  32 , printing is performed by a print head  34  which moves along the top surface of the printing sheet  18  in the width direction (transverse direction). Additionally, the platen  32  has multiple small holes on its top surface, and the small holes are sucked to a negative pressure by an evacuate fan  36 . Therefore, the printing sheet  18  is sucked onto a surface of the platen  32  by a suction pressure acting on the small holes, and fixedly adheres to the surface of the platen  32 . 
     The print head  34  is of a piezo-ink jet system in which a piezoelectric element pressurizes a slight amount of ink to eject ink droplets to the printing sheet  18 , and four color ink ejecting nozzles of cyan, magenta, yellow and black are arranged in feeding direction of the printing sheet  18 . The print head  34  may be of a system other than the piezo-ink jet print system. For example, a bubble jet print system for heating ink to jet ink drops, a heat transfer recording system, or the like may be used. The print head  34  moves along the top surface of the printing sheet  18  held by the platen  32  in the width direction to print the printing sheet  18 . 
     The printing sheet  18  is passed under the print head  34 , fed between a pair of upper and lower sheet rollers  38  and  40  to be discharged from the printer section, further passed between a pair of upper and lower guide plates  42 ,  44 , and guided downward by a guide plate  46 . The printing sheet  18  is placed into a large-sized basket-like tray  48  which is attached between the pair of opposite legs  16 . 
     Numeral  50  denotes an ink tank device. As shown in FIG. 2, the ink tank device  50  is disposed on the rear face of the case  12 , and includes four ink tanks  52  which can be detachably mounted from rear. The four ink tanks  52  contain inks of four colors corresponding to the four color ink ejecting nozzles of the print head  34 , i.e., inks of cyan, magenta, yellow and black, respectively. 
     Pressurized air is supplied from the printer unit  10  to the ink tanks  52 , and the inks of the tanks  52  are fed under air pressure to the print head  34 . Numeral  54  denotes a bundle of four tubes for guiding the inks from the tanks  52  to the print head  34 . Numeral  56  denotes a drain tank for collecting the waste inks which have been ejected for cleaning of the jetting nozzles of the print head  34 . 
     A cutter device will next be described. A cutter  60  is disposed close to one edge of the printing sheet  18  between the guide plates  42 ,  44  and the guide plate  46 . The cutter  60  cuts the printed sheet  18  while moving from the left end to the right. Additionally, since the printing sheet  18  has a broad width (about 54 inches at maximum), its cut portion hangs downward while the cutter  60  is moving, and its uncut portion is wrinkled. A clear cutting is thus impossible. 
     In the present invention, an end of the cut printing sheet is pressed or fixed by a pressing member or pressing lever  62  from above on the cutting start side of the cutter  60 . Specifically, the guide plate  46  and the pressing member  62  serve as sheet holding means in the cutter device of the embodiment. When the cutter  60  reaches the terminal end of the printing sheet  18 , the pressing lever  62  is raised to release the printing sheet  18 . Therefore, since the right and left ends of the cut printing sheet  18  drop substantially simultaneously, printed sheets are orderly collected on the tray  48  without being wrinkled. 
     The cutter  60  will next be described with reference to FIGS. 3 to  5 . The cutter  60  is held by a horizontal guide rail (not shown) in such a manner that it can horizontally move, and opposite ends of a wire  68  are fixed to the cutter  60 . The wire  68  is wound around two pulleys  64 ,  66  positioned outside the entire width of the sheet  18 . One pulley  64  is rotated forward or in reverse by a motor  70 . As a result, the cutter  60  can be moved by the motor  70  to reciprocate in the width direction of the sheet  18 . The cutter  60  preferably reciprocates to cut the sheet  18  at a speed of about 0.5 to 2.0 m/sec, and can preferably cut a 54 inch wide sheet in about one second. 
     The cutter  60  includes a pair of upper and lower rotating blades  72 ,  74 , which slightly overlap each other in vertical direction as seen in the front view of FIG.  4 . The overlapped portion of the blades  72 ,  74  is opposed to the left edge of the sheet  18 . Additionally, rotating faces of the rotating blades  72 ,  74  are parallel with the width direction of the sheet  18 . A pulley  76  having a diameter smaller than that of the lower rotating blade  74  is integrally fixed to the blade  74 , and a wire  78  extended parallel with the wire  68  is wound around the small diameter pulley  76 . Opposite ends of the wire  78  are fixed to frames  80 ,  80  of the printer unit  10  (FIG.  4 ). 
     Therefore, when the wire  68  runs in the width direction (transverse direction) of the sheet  18  by the rotation of the motor  70 , the cutter  60  to which the opposite ends of the wire  68  are fixed moves right and left. Then, the pulley  76  of the rotating blade  74  moves relative to the fixed wire  78 , the movement causes the pulley  76  to rotate and move on the fixed wire  78  and, consequently, the rotating blade  74  is rotated. Since the pulley  76  has a sufficiently smaller diameter than that of the rotating blade  74 , the peripheral speed of the rotating blade  74  becomes sufficiently higher as compared with the travel speed of the cutter  60 . When the upper and lower rotating blades  72  and  74  move from the left side toward the sheet  18  and the sheet  18  enters the overlapped portion of the rotating blades  72 ,  74 , the sheet  18  is quickly cut between the rotating blade  74  rotating at a high speed and the upper rotating blade  72  rotated following the rotation of the blade  74 . 
     The position of the cutter  60  may be detected by a photo sensor or the like. For example, when a light shielding plate  82  fixed to the wire  68  passes between a light emitting element  84  and a light receiving element  86  which are attached to a frame side, the position of the cutter  60  can be detected. In the embodiment the light emitting and receiving elements  84  and  86  are positioned in accordance with the width of the sheet  18 . 
     As shown in FIGS. 3,  6 A and  6 B, the pressing lever  62  as the pressing member is swung vertically by an electromagnetic solenoid  88 . Specifically, the pressing lever  62  is formed like as a bell-crank which swings centering on a support  90 , and has one end extended to above the left end of the printed sheet  18  and the other end pivoted or attached to a tip end of a plunger of the solenoid  88 . The plunger tip end is biased in protruding direction by a tensile spring  92 . 
     Therefore, at the time of non-excitation of the solenoid  88 , the tensile spring  92  restores the plunger to its protruded position, and releases the extending end of the pressing lever  62  from the sheet  18  (as seen in FIG.  6 A). Additionally, at the time of excitation of the solenoid  88 , the plunger of the solenoid  88  is drawn into the solenoid  88  against the reset force of the tensile spring  92 . The pressing lever  62  rotates in clockwise direction in FIG. 6B, and the extending end of the lever  62  presses the sheet  18  from above. Accordingly, the sheet  18  is held between the lever  62  and the guide plate  46 . Additionally, the extending end of the pressing lever  62  may be provided with a pad  94  for increasing the friction with the sheet  18 . 
     In FIG. 3, numeral  96  denotes a controller which controls the cutter  60  and the solenoid  88  in accordance with a cutting command entered from another control device, a manual switch, or the like. Moreover, when the cutting of the sheet  18  is completed to return the cutter  60  to its reset or home position, the sheet  18  is preferably fed in reverse by only a small amount in its rewinding direction in order to avoid interference of the cut end of the sheet  18 , which is left on the side of the printer unit  10 , with the cutter  60 . In this case, the controller  96  supplies an instruction to a feed motor  98  to rotate in reverse so that the feed roller  30  is operated to rotate in reverse. 
     The entire operation will next be described with reference to an operation timing chart of FIG.  7 . While image recording or printing is performed by the print head  34 , the feed motor  98  (FIG. 3) rotates forward to feed the sheet  18  forward, i.e., in a direction in which the sheet  18  is drawn from the roll  20 . After the recording (printing) is completed, upon receipt of a cutting command, the controller  96  (FIG. 3) further rotates the feed motor  98  forward by a predetermined amount until the cutting position of the sheet  18  reaches to the position of the cutter  60 . After the positioning is completed (at timing T 1  of FIG.  7 ), the controller  96  excites the solenoid  88  to actuate the pressing lever  62  so that the sheet  18  is held between the pressing lever  62  and the guide plate  46 . 
     In order to ensure the holding of the sheet  18  by the pressing lever  62 , the controller  96  starts the movement of the cutter  60  with a slight delay (t 1 ) after the start of the excitation of the solenoid  88 . Specifically, after the delay t 1 , the controller  96  energize the motor  70  to move the cutter  60  at a high speed so that the sheet  18  is cut. The excitation of the solenoid  88  is stopped immediately before timing T 2  at which the cutter  60  reaches the right end (terminal end) of the sheet  18 . Time t 2  is set in consideration of a delay from the time when the excitation of the solenoid  88  is stopped to release the pressing lever  62  from the sheet  18  to the time when the sheet  18  indeed starts dropping. 
     With such an operation, when the cutter  60  reaches the right end and finishes cutting, the left end of the sheet  18  is substantially simultaneously released from the pressing lever  62 . Accordingly, the right and left ends of the sheet  18  start dropping substantially simultaneously before entering the tray  48 . Therefore, during the cutting operation, there does not occur a problem such that only the left end of the cut sheet  18  drops while an uncut portion is wrinkled or surged. The cutter  60  can cut the sheet  18  straight with a clear cut line. 
     Subsequently, the cutter  60  returns from the right end to its reset or standby position on the left end, but prior to the returning, the controller  96  feeds the non-printed sheet  18  in reverse by a predetermined amount by rotating in reverse the feed motor  98  with a slight delay t 3  from the time at which the cutter  60  reaches the right end. By the reverse feeding, the cut end of the non-printed sheet  18  can be prevented from interfering with the returning cutter  60 . 
     The reverse feed amount may be an excessively small amount but enough to allow the cutter  60  to avoid the interference with the sheet  18  (dots and dash line A in FIG.  7 ). Otherwise, the sheet  18  may be returned to a position from which the next printing operation starts (solid line B in FIG.  7 ). 
     As aforementioned, just before the cutter  60  reaches the right end of the sheet  18  the excitation of the solenoid  88  is stopped and the sheet  18  is released from the pressing lever  62 . The timing for stopping of the excitation of the solenoid  18  can be determined in various methods. For example, in a case where the travel speed of the cutter  60  (rotating speed of the motor  70 ) is considered to be constant, the timing can be determined by a time elapsed after the cutter  60  starts traveling. Additionally, by actually cutting the sheet  18 , the timing can be manually set. Moreover, by detecting the position of the cutter  60  with the light emitting and receiving elements  84  and  86  described above or the like, the timing optimum for the sheet width may be determined. 
     In the embodiment, the pressing member is formed by the pressing lever  62  and swung by the solenoid  88 , but the present invention is not limited thereto. It may essentially be a pressing member for holding the end of the sheet  18  to prevent the end from dropping. Therefore, the sheet may be pressed by a lever or a rod, but the sheet may be held by sucking the sheet by a negative suction pressure. 
     As aforementioned, in the present invention, the end of the sheet on the cutting start side is held or pressed and prevented from dropping, and the sheet is released from the pressing member substantially in synchronism with the time when the cutter reaches the end on the cutting completion side. Therefore, the sheet does not need to be pressed with a long member which transverses the sheet in its width direction, and the present invention is suitable for compactness of the device. 
     Additionally, since the end of the sheet is only pressed, a large space can be obtained above the sheet. Therefore, a new sheet can be easily set, and good operability can be provided. 
     Here, the sheet is preferably fed in reverse in its rewinding direction, within the time between after the cutter finishes cutting and before the cutter returns to its original position. With such a construction, the cut end of the non-printed sheet fails to interfere with the returning cutter, and the sheet is prevented from being damaged. 
     The cutter preferably includes rotating blades which rotate at a high speed accompanying the travel of the cutter, and cuts the entire width of the printing sheet at once at a high speed. As the cutting operation proceeds, the cut portion of the sheet increases and the weight of the cut portion of the sheet becomes heavier, resulting in the large application of the load to the uncut portion of the sheet. With high speed cutting operation by using rotating blades, the completion of the sheet cutting can be realized without damages of the sheet due to the excess load applied to the sheet in the position held by the pressing member. Also, the pressing force of the pressing member can be minimized. Additionally, the portion around the center of the sheet in its width direction can be securely prevented from hanging downward. In this case, the cutter can preferably finish cutting at once at a speed of about 0.5 to 2.0 m/sec.