Abstract:
A point of sale printer is provided with a large paper supply roll mounted externally from the printer. The printer includes a paper drive which rapidly accelerates and decelerates a paper web extending from the paper supply roll. A tensioning roll is moved in one direction to feed the web into the printer during the relatively slow acceleration of the paper supply roll and in an opposite direction to prevent a tangle of paper as the paper supply roll is decelerated after the printer stops moving the paper web. A cable assembly is provided to facilitate loading the large paper supply roll. A braking spring helps to decelerate the paper supply roll and further engages a flap formed in an outer end of the paper web to thread this end of the web into the printer.

Description:
CROSS-REFERENCE TO A RELATED APPLICATION  
       [0001]    This application is related to a U.S. application, docket No. RPS9-2000-0123US1, filed on an even day herewith, entitled “Paper Roll Retention System for a Point of Sale Printer, having the same assignee as the present invention. 
     
    
     
       BACKGROUND INFORMATION  
         [0002]    1. Field of Invention  
           [0003]    This invention relates to a point of sale printer having a large paper roll supply, and, more particularly, to such a printer having a large supply paper roll mounted beneath a counter surface extending under the printer, and to apparatus for controlling the rotational acceleration and deceleration of a massive paper supply roll as movement of a paper web through the printer is suddenly started and stopped.  
           [0004]    2. Background Art  
           [0005]    Point of sale printers have typically been used to print sales receipts. A recent trend in the use of such printers is an increased acceptance of thermal printing methods, which provide for operation at much faster printing speeds. The availability of faster printing speeds has led to including additional printed material on sales receipts. For example, many sales receipts now include store logos, advertisements, barcodes, and statements of store policy, especially regarding the return of purchased merchandise. Such additional printed material greatly increases the length of typical receipts. While faster printing speeds allow the generation of such longer receipts without significantly slowing the checkout process, the increased length of receipts results in an increased frequency in which paper supply rolls must be changed.  
           [0006]    A number of improvements have been made in the simplification of the process of loading new paper supply rolls, providing, for example, a “drop and load” feature for a point of sale terminal. An example of such an improvement is found in U.S. Pat. No. 5,060,877, which describes an automatic paper feed apparatus including a receptacle for a paper roll. Within the receptacle, the paper roll rests upon a guide roll and a first feed roll which is capable of rotating the paper roll to feed a paper web from the roll. A guide chute is provided which guides movement of the paper web from the paper roll to an exit portion of the guide shoot, from where it may be introduced into a printer or other device. The guide chute is comprised of a portion of the floor of the receptacle and a movable upper element. The movable upper element is pivotally mounted at one end on the shaft associated with the first feed roll. A second feed roll is positioned between the ends of the guide chute to drive the paper web through the guide chute, and cooperates with pressure rolls mounted on the upper element of the guide chute. A motor is provided for driving the first and second feed rolls.  
           [0007]    While the time required to change paper supply rolls is certainly reduced by such improvements, a new paper supply roll must be found when it is needed, and the resulting process of changing rolls disrupts the process of checking out merchandise. Thus, what is needed is a way to provide significantly more paper in a single supply roll, so that the frequency of changing rolls is significantly reduced.  
           [0008]    U.S. Pat. No. 4,808,800 describes apparatus for providing an additional and somewhat larger paper roll for an electronic printer calculator, which then contains rolls of paper outside and inside the calculator and a printer for printing out data on either of the rolls of paper. A passage for leading the roll paper set outside the calculator main body to the printer is separate from that for leading the roll paper set inside the calculator main body to the printer.  
           [0009]    While the apparatus of U.S. Pat. No. 4,808,800 does provide for a somewhat larger roll of supply paper, what is needed is a much larger roll which is mounted in a location spaced away from the printing mechanism. Furthermore, what is needed is a method for dealing with the rotational inertia of a large roll of paper, both in terms of accelerating the roll to a peripheral speed sufficient to supply paper for a modern high-speed point of sale printer, and in terms of decelerating the roll when the printing process has been stopped without spooling off a substantial portion of the paper web.  
         SUMMARY OF THE INVENTION  
         [0010]    Thus, it is a first objective of the present invention to provide a substantially larger paper supply roll for a point of sale terminal;  
           [0011]    It is a second objective thereof to provide a means for rotationally accelerating a massive paper roll as a printer suddenly begins moving a paper web from the roll to print;  
           [0012]    It is a third objective thereof to provide a means for minimizing the unspooling of a paper web during deceleration of a massive paper roll after a printer suddenly stops moving a paper web from the roll to print;  
           [0013]    It is a fourth objective thereof to provide a means facilitating the loading of a massive paper roll into paper feed apparatus for a printer; and  
           [0014]    It is a fifth objective thereof to provide a means for retaining a paper web extending upward into a printer in position within a paper feed apparatus when an upper end of the paper web is released by a printer.  
           [0015]    It is a sixth objective thereof to provide a means to facilitate threading a paper web from a paper supply roll under the counter into a printer on the counter.  
           [0016]    According to a first aspect of the present invention, paper supply apparatus is provided for a printer having a paper drive moving a paper web through the printer in a paper feeding direction. The paper supply apparatus includes a roll mounting bracket, a spindle, a tensioning roller, and a tensioning roller support structure. The roll mounting bracket is disposed externally from the printer. The spindle removably and rotatably mounts a paper supply roll in the roll mounting bracket. The tensioning roller applies a tensioning force to a portion of the paper web extending between the paper supply roll mounted on the spindle and the printer. The tensioning roller support structure constrains the tensioning roller to move along a preferred path, with the tensioning roller moving along the preferred path in a first direction as the paper roll is accelerated to rotate in an unspooling direction in response to the paper drive starting to move the paper web through the printer, and with the tensioning roller moving along the preferred path opposite the first direction as the paper roll is decelerated in response to the paper drive stopping movement of the paper web through the printer.  
           [0017]    According to a second aspect of the present invention, paper supply roll mounting apparatus is provided for a printer having a paper drive moving a paper web from a paper supply roll through the printer in a paper feeding direction. The paper supply apparatus includes a roll mounting bracket, a spindle, and a cable extending on each side of the spindle. The roll mounting bracket is disposed externally from the printer. The spindle removably and rotatably mounts a paper supply roll in the roll mounting bracket and includes a shaft having a first pulley attached at a first end of the shaft and a second pulley removably attached at a second end of the shaft. The cable engages the first and second pulleys between an anchor point and a handle, with the spindle being movable into the slot at each side of the roll mounting bracket while the spindle is held in suspension by the cable. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 is an isometric view of various components of a point of sale printer having a large paper supply roll, built in accordance with the present invention, in an exploded relationship with one another;  
         [0019]    [0019]FIG. 2 is an elevation of the point of sale printer of FIG. 1; and  
         [0020]    [0020]FIG. 3 is an isometric view of an alternative paper tensioning device built in accordance with the present invention.  
     
    
     DESCRIPTION OF THE INVENTION  
       [0021]    Referring to FIG. 1, a point of sale printer  10  is mounted atop a counter  12  by means of a printer mounting plate  14 . The point of sale printer  10  is, for example, an IBM 4610-TM6 thermal printer, which prints at a paper speed of approximately 16.5 cm/sec (6.5 in/sec). In accordance with the present invention, the printer  10  draws a paper web from a large roll  16 , rotatably mounted beneath the counter  12 , within paper supply apparatus generally indicated as  18 . The large paper roll  16  has a diameter as large as 38 cm (15 in.), holding about 25 times as much paper as a conventional paper roll for a point of sale printer.  
         [0022]    A spindle assembly, including a shaft  19 , a first spindle pulley  20  pressed onto the shaft  19 , and a first cable guide  21 , is slid into a central hole (not shown) within the large paper roll  16 . The large paper roll  16  is further held in place on the spindle assembly by means of a second pulley  22 , which is snapped into a detent surface (not shown) on the shaft  19 , along with a second cable guide  23 . When the large paper roll  16  is fully installed within the apparatus of FIG. 1, the cylindrical hubs  26  of the pulleys  20 ,  22  extend through end portions  28  of slots  30  within a roll mounting bracket  32 . The roll mounting bracket  32  is fastened to a bracket mounting plate  34  to extend downward when the bracket mounting plate  34  is mounted to a lower surface of the counter  12 . In this way paper roll  16  is moun ted to rotate about its center within the roll mounting bracket  32 .  
         [0023]    The paper supply apparatus  18  also includes a web tensioning device, generally indicated as  35 , a braking spring  36 , and a paper loading cable assembly  38 .  
         [0024]    Continuing to refer to FIG. 1, and additionally referring to FIG. 2, a paper web  40 , pulled from the large paper roll  16  extends under a tensioning roller  42 , which is mounted to slide and rotate within a vertical slot  44  in a tensioning bracket  46 , forming the web tensioning device  35 . The paper web  40  extends upward through a slot  48  in the bracket mounting plate  34 , a slot  50  in the counter  12 , a slot  52  in the printer mounting plate  14  and a slot  54  in the base of the printer  10 .  
         [0025]    The printing process is typically begun with the paper web  40  and the tensioning roller  42  in the positions shown in FIG. 2. Movement of the paper web  40  through the printer  10 , upward in the direction of arrow  58 , is controlled by a drive roll  60 , which is rotationally driven to move the paper web  40  against a thermal print head  62 . The thermal print head  62  includes a number of heating elements which are turned on and off to produce visible markings on a thermally sensitive surface of the paper web  40 . In this way, the paper web  40  is very rapidly accelerated to a printing speed of, for example, 16.5 cm/sec (6.5 in/sec). The rotational moment of inertia of the large paper roll  16  prevents its rapid acceleration to a rotational speed allowing the paper web  40  to be pulled from the roll  16  at the such a speed. Instead, the tensioning roller  42  is initially pulled upward, toward the position indicated by a dashed line  64 , as the paper web is moved into the configuration indicated by dashed lines  66 . Upward movement of the tensioning roller  42  allows the paper web  40  to be pulled upward into the printer without a corresponding rotation of the large paper roll  16 . However, the weight of the tensioning roller  42  causes a torque to be applied to large paper roll  16  through the paper web extending between the tensioning roller  42  and the paper roll  16 , so that the paper roll  16  is accelerated in the paper unspooling direction of arrow  68 . The tensioning roller  42  continues downward as the paper supply roll  16  is brought up to a peripheral speed matching the speed at which the paper web  40  is moved through the printer  10 . When these speeds match, the drive roll  60  within the printer  10  continues to pull paper with the paper roll  16  turning at a constant speed, and with the tensioning roller rotating at a constant elevation, generally between the position in which it is shown in FIG. 2 and its uppermost position, indicated by dashed lines  64 . During this portion of the printing operation, the drive roll  60  easily overcomes friction within the paper supply apparatus  18 , without a need to overcome the inertia of the large paper roll  16 .  
         [0026]    When the printer  10  finishes a printing operation, the drive roll  60  abruptly stops, terminating movement of the paper web  40  into the printer  10 . The paper roll  16  begins to decelerate, primarily due to friction between its periphery and the braking spring  36 . This friction limits the additional rotation of the paper roll  16 , after the drive roll  60  within the printer is stopped. Without this limitation, the rotational energy stored within the paper roll  16  would cause enough continued rotation of the paper roll  16  to unspool a significant length of the paper web  40 , which could otherwise become tangled within the paper feed apparatus  18  due to a lack of control of its configuration. As the paper web  40  is unspooled with the drive roll  60  stopped, the tensioning roller  42  moves downward into its lowest position, in which it is shown in FIG. 2.  
         [0027]    Thus, the tensioning device  35  and the braking spring  36  provide a buffer between the need of the printer  10  to start and stop the movement of paper therethrough very rapidly and the need of the massive paper roll  16  to accelerate and decelerate rotationally relatively smoothly and slowly.  
         [0028]    The braking spring  36  is formed as a cantilever spring extending downward, opposite the direction of arrow  58 , through an aligned series of slots  48 ,  50 ,  52 ,  54  and rightward, in the direction of arrow  70 . The braking spring  36  is held in place by a tab  71  extending along an internal surface  72  of the printer  10 , with the braking spring  36  being deflected by the peripheral surface of the large paper roll  16  when this roll  16  is installed in the paper supply apparatus  18 , and to move upward as the paper roll  16  is reduced in diameter with the usage of paper. The braking spring  36  is also supported by resting against a central segment  73  of the tensioning bracket  46 . The braking spring  36  exerts less force on the peripheral surface of the paper roll  16  as this roll is reduced in diameter with paper usage, but less frictional force is required to stop the smaller roll properly, without spooling off too much paper during deceleration. Before all of the paper is used, the paper roll  16  may become small enough to move out of contact with the braking spring  36 , but a roll this small does not require the braking spring  36  to stop properly.  
         [0029]    The paper loading cable assembly  38  is used to facilitate loading the paper roll  16 , which weighs about 6.8 Kg (15 lb.), into the paper feed apparatus  18 . The cable assembly  38  includes a flexible cable  74  having ends  75  anchored at holes  76  on opposite sides of the roll mounting bracket  32 . The flexible cable  74  extends over pulleys  78 , which are rotatably mounted on the roll mounting bracket  32  close enough to its central section  80  to entrap the cable  74  in the flanged periphery of the pulleys  78 , while allowing rotation of the pulleys  78 . During the process of assembling the paper supply apparatus  18 , the pulleys  78  are pressed on a shaft  79  to turn together. The flexible cable  74  also extends through a hole  82  of a handle  84  and within cable guiding slots  86  of the cable guides  21 ,  23 .  
         [0030]    The paper roll  16  is assembled onto the paper loading cable assembly  38  by inserting a spindle assembly including the shaft  19 , the first spindle pulley  20 , and the first cable guide  21 , into the central hole (not shown) within the paper supply roll  16 . A second assembly, including the second spindle pulley  22  and the second cable guide  23 , is then snapped in place on the end of the shaft  19  opposite the first spindle pulley  20 . From this point, the first and second spindle pulleys  20 ,  22  turn together with the shaft  19 , but the cable guides  21 ,  23  rotate relative to the shaft  19 . The cable  74  is constrained to slide within the cable guiding slots  86  of the cable guides  21 ,  23 . This part of the paper loading process is performed with the cable  74  in a slack condition, and preferably with the paper roll  16  resting on the braking spring  36 , which extends on a shelf (not shown) forming an intermediate or lower surface within a cabinet below the counter  12 . Next, the handle  84  is pulled to tighten the cable  74 , lifting the pulleys  20 ,  22  and thus the paper roll  16 , with the pulleys  78  turning together on shaft  79  to help maintain balanced tension in both sides of the cable  74 . In this way, the paper roll  16  is lifted by exerting a pulling force equal to about half its weight. The hubs  26  of the pulleys  20 ,  22  are first brought into alignment with the opening of the slots  30  on each side of the roll mounting bracket  32 , as the spindle assembly and paper roll  16  are held in suspension by the cable assembly  38 , and are then moved within the slots  30 . The manual pulling force provided through the handle  84  is then reduced, so that the hubs  26  drop into the ends  28  of the slots  30 . From this point, the weight of the paper supply roll  16  holds the hubs  26  in place.  
         [0031]    To facilitate the loading or removal of paper, a top cover  86  of the printer  10  is preferably pivotally mounted to open into the position in which it is indicated by dashed lines  88  in FIG. 2. The drive roll  60  is rotatably mounted to move with the top cover  86 , so that it pulls away from the print head  62  into the position indicated by dashed lines  90  in FIG. 2 as the top cover  86  is opened. In this way, the paper web  40  is released from being held within the printer  10 . When the upper end of the paper web  40  is released in this way, the weight of tensioning roller  42 , already in the lowest position, in which it is shown in FIG. 2, clamps the paper web  40  between the roller  42  and an adjacent surface  92  of the braking spring  36 . The inclination of this surface  92  relative to the slot  44  in which the roller  42  moves provides a mechanical advantage causing the paper web  40  to be clamped securely in place. In this way, the paper web  40  is not allowed to fall downward, out of the printer  10  and into the paper supply apparatus  18 , from which its retrieval would otherwise be inconvenient.  
         [0032]    The braking spring  36  is preferably mounted in a manner allowing it to be slid upward, through the slots  48 ,  50 ,  52 , when the top cover  86  of the printer  10  is opened as described above. (In FIG. 1, the braking spring  36  is shown below the bracket mounting plate  34  in order to depict its relationship with the paper roll  16 , despite the fact that the braking spring  36  cannot be installed from below the bracket mounting plate  34 .) The braking spring  36  includes a tab  94  which allows the use of the braking spring to thread the paper web  40  through the apparatus  18 .  
         [0033]    To use this feature after the paper roll  16  is installed within the paper feed apparatus  18 , an outer end of the paper web is folded along a line  96  to form a flap  98 , and the paper roll  16  is manually turned to bring the flap  98  of the paper web into engagement with the braking spring  36 , extending under the tab  94 . Then, with the top cover  86  open, the braking spring  36  is pulled upward, in the direction of arrow  58 , with the paper web being also pulled upward in engagement with the braking spring  36  at the tab  94 . After flap  98  of the paper web is pulled upward, into the printer  10  in this way, it is disengaged from the braking spring  36 , which is then returned downward until its tab  71  rests upon the associated internal surface  72  of the printer  10 .  
         [0034]    Referring to FIG. 3, an alternative paper tensioning device, generally indicated as  100 , includes tensioning bracket  102  having an arm  104  pivotally mounted to extend from each side of the roll holding bracket  32 , with a central portion  106  extending between the arms  104 . A tensioning roller  108  is rotatably mounted within the tensioning bracket  102  to extend between the arms  104 . The roller  108  is held downward against the paper web  40  by means of an extension spring  110  providing a torque on each of the arms  104 . A spring support bracket  112 , extending from the roll holding bracket  32 , holds the braking spring  36  in place.  
         [0035]    While the invention has been shown in its preferred forms or embodiments with some degree of particularity, it is understood that this description has been given only by way of example, and that numerous changes in the details of construction, fabrication, and use, including the combination and arrangement of parts, may be made without departing from the spirit and scope of the invention.