Patent Document

BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a paper roll holder for a printer, and, more particularly, to a mechanism allowing the paper roll to be either snapped into place between bearing members or dropped into place within the holder. 
   2. Summary of the Background Art 
   Many printers, especially the small point-of-sale printers used to generate sales receipts, use roll paper to achieve the advantages of easy loading, reliable feeding, and of an ability to generate receipts that vary greatly from one another in length. Some such printers provide for snap-in loading of the paper roll, in which a cylindrical center portion of the paper roll is held to rotate between a pair of spring-loaded bearing members. Other such printers provide for drop-in loading, in which the paper roll is dropped into a cavity or bucket that holds the roll by its periphery as the roll rotates. As paper is pulled from the roll during the printing process, the roll rotates within the cavity, being supported by rollers or by a curved surface within the cavity. 
   A printer configured for holding a snap-in paper roll is described, for example, in U.S. Pat. No. 6,536,696, with the paper roll being held between two inwardly spring loaded spherical bearing members. Spring loaded bearing members having spherical contact surfaces are also used in other applications, such as holding toilet paper or paper toweling, as described in U.S. Pat. No. 4,614,312, and for holding a roll of photographic film within a camera, as described in U.S. Pat. No. 1,402,167. Within a printing device or copier, a paper roll having a cylindrical core may alternately be held by means of spring loaded bearing members having truncated conical surfaces, as described in U.S. Pat. No. 4,821,974, or a paper roll may be held between flanges mounted on a shaft having tapered shafts fitting into cup-shaped holders as described in U.S. Pat. No. 4,821,974. Spring-loading may be accomplished by placing springs at each of the bearing members or at only one of the bearing members. Spherical bearing members have an advantage of allowing the roll to be snapped into place with a straight movement into the holder, with the use of springs at both ends reducing the amount of movement required and centering the paper roll. 
   U.S. Pat. No. 5,060,877 describes an automatic version of drop-in loading, in which the paper roll, having been dropped into place atop rollers within a cavity, is caused to rotate by spinning the rollers, so that the end paper web is automatically fed into a channel from the roll. 
   Some users of point-of-sale printers prefer drop-in paper roll loading, because of its inherent simplicity and because of the speed with which it can be accomplished. Other users favor snap-in loading because the paper roll is aligned more accurately within the printer. Therefore, what is needed is a paper roll holder that can be easily converted between snap-in loading and drop-in loading. 
   SUMMARY OF THE INVENTION 
   According to one aspect of the invention, apparatus is provided for rotatably holding a paper supply roll, having a cylindrical peripheral surface and a hollow cylindrical core, within a printer. The apparatus includes a lower support surface for engaging the peripheral surface of the paper supply roll, a cavity for holding the paper supply roll, extending within the printer above the lower support surface; a pair of spaced-apart side plates disposed within the cavity and a pair of bearing members. Each of the side plates includes a mounting structure. Each of the bearing members is held within one of the mounting structures, The bearing members are held in axial alignment with one another. Each of the bearing members includes a tapered surface for engaging the hollow cylindrical core. Each of the bearing members is mounted to be moved between an inward position having the tapered surface of the bearing member disposed within the space between the side plates and an outward position having the tapered surface of the bearing member held out of the space between the side plates. Each of the bearing members is held in the inward position and in the outward position. 
   According to other aspects of the invention, apparatus is provided for rotatably holding an end of a paper supply roll, having a cylindrical peripheral surface and a hollow cylindrical core, within a printer, with the apparatus including a bearing member and a side plate. In one embodiment, the bearing member includes a tapered surface for engaging the hollow cylindrical core and a flat surface opposite said tapered surface, and the side plate includes a mounting structure holding the bearing member in an inward position with the tapered surface facing in an inward direction to engage the hollow cylindrical core and in an outward position, with the tapered surface facing opposite the inward direction. In another embodiment, the bearing member includes a tapered surface for engaging the hollow cylindrical core; and the side plate includes a mounting structure holding said bearing member in an inward position with the tapered surface engaging the hollow cylindrical core and in an outward position, with said tapered surface held out of engagement with the hollow cylindrical core 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a receipt printer including a paper roll holder built in accordance with a first embodiment of the invention, configured to provide for drop-in loading; 
       FIG. 2  is a perspective view of a spring within the paper roll holder of  FIG. 1 , shown in an exploded relationship with a bearing member used therein; 
       FIG. 3  is a perspective view of the bearing member of  FIG. 2 , oriented to show a flat side thereof; 
       FIG. 4  is a perspective view of the receipt printer of  FIG. 1 , configured to provide for snap-in loading; 
       FIG. 5  is a fragmentary cross-sectional view of the receipt printer as shown in  FIG. 4 , taken as indicated by section-line  5 — 5  therein; 
       FIG. 6  is a fragmentary cross-sectional view of the receipt printer as shown in  FIG. 4 , taken as indicated by sections-line  6 — 6  in  FIG. 5 ; 
       FIG. 7  is a fragmentary side elevation of a receipt printer showing a roll paper holder built in accordance with a second embodiment of the invention; 
       FIG. 8  is a fragmentary cross-sectional view of the receipt printer of  FIG. 7 , taken as indicated by section line  8 — 8  therein; and 
       FIG. 9  is a perspective view of a bearing member within the receipt printer of  FIG. 7 , shown in an exploded relationship with a mounting structure of a side plate within the printer, in which the bearing member is mounted. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  is a perspective view of a receipt printer  10  including a paper roll holder  12  built in accordance with a first embodiment of the invention and configured to provide for drop-in loading of a paper supply roll. The receipt printer  10  is shown as opened, with an upper cover  14  pivoted upward for paper loading, having received a paper supply roll  16 . The paper roll  16  has been dropped into a cavity  18  to rest on a curved lower support structure  20 , extending below the cavity  18  within the receipt printer  10 . During the paper loading process, the outer end  22  of the paper web  24  forming the roll  16  is pulled outward so that the web  24  extends through a slot formed between a front cover surface  26  of the upper cover  14  and an adjacent surface  28  of the printer housing  30 . When the upper cover  14  is then closed, the paper web  24  passing by a printing mechanism (not shown) and a drive roller  32  that is rotated to move the paper through the printing process. 
   The paper roll holder  12  includes a pair of bearing members  34  held within holes  36  extending through side plates  38  that pivot with the upper cover  14 . Each of the bearing members is spring loaded inward, toward the space  39  between the side plates  38 , by a bearing member mounting structure formed as a wire spring  40 . While only one of the wire spring mounting structures  40  is visible in the figure, it is understood that each of the bearing members  34  is held inward by a corresponding wire spring mounting structure  40 . (The specification herein of an “inward” direction means toward the center of the space  39  between the side plates  38 , regardless of which of the two bearing members  34  is being discussed, while an “outward” direction is opposite to the “inward” direction.) 
   The characteristics of the wire spring mounting structure  40  and the bearing member  34  will now be discussed with particular reference being made to  FIGS. 2 and 3 .  FIG. 2  is a perspective view of the wire spring mounting structure  40  in an exploded relationship with the bearing member  34 , while  FIG. 3  is a perspective view of the bearing member  34  rotated so that a flat surface  42  thereof is visible. 
   Each of the bearing members  34  includes a tapered surface  44  that extends from an axis  46  of the bearing member, with the tapered surface  44  increasing in diameter with movement along the tapered surface  44  away from an intersection  48  of the tapered surface  44  and the axis  46 . For example, the tapered surface  44  is formed as a portion of a sphere. The tapered surface  44  extends along the bearing member  34  opposite the flat surface  42 . Each of the bearing members  44  also includes a hole  50 , extending through the bearing member  44 , within parallel slots  52  extending along partly-flattened opposite sides  54  of the bearing member  44 . The parallel slots  52  extend perpendicular to the flat side  42  of the bearing member. 
   The wire spring mounting structure  40  includes a U-shaped portion  42  from which a pair of legs  56  extend inward, in the direction of arrow  57 , toward the space  39  between the side plates  38 , when the spring mounting structure  40  is held in place on either of the two side plates  38 . An end portion  58  of the spring mounting structure  40  extends from the end of each of the legs  56 . 
   The bearing member  34  is assembled to the wire spring mounting structure  40  by spreading the end portions  58  so that they can fit into opposite sides of the hole  50  extending through the bearing member  34 . The end portions  58  are then brought toward one another within the hole  50  so that the legs  56  extend within the slots  52  at each side of the bearing member  34 . As this is done, the bearing member  34  may be oriented as shown in  FIGS. 1 and 2 , with the flat side  42  thereof facing inward, in the direction of arrow  57 , and with the tapered surface  44  facing outward, opposite the direction of arrow  57 . This orientation places the bearing member  34  in an outward position, with the tapered surface  44  being held out of the space  39  between the side plates  38 , providing for drop-in loading of the paper supply roll  16 , which, upon being installed within the cavity  18 , comes to rest against the lower support surface  20  without being stopped by engagement with one of the tapered surfaces  44 . The space  39  is wider than the paper roll  16  to be inserted. 
     FIGS. 4 and 5  show the printer  10  configured to provide for snap-in loading of the paper supply roll  16 , with  FIG. 4  being a perspective view thereof, and with  FIG. 5  being a fragmentary cross-sectional view thereof, taken as indicated by section lines  5 — 5  in  FIG. 4 . In  FIG. 4 , the receipt printer  10  is shown as opened, with the upper cover  14  pivoted upward for paper loading, having received the paper supply roll  16  to be held between the two bearing members  34 . 
   To provide for snap-in loading of the paper roll, each of the bearing members  34  is held within a corresponding wire spring mounting structure  40  so that, when the wire spring mounting structure  40  is installed to extend along the corresponding side plate  38 , the tapered surface  44  of the bearing member  34  faces inward, in the direction of arrow  57 , while the flat surface  42  of the bearing member  34  faces outward, opposite the direction of arrow  57 . As the paper supply roll  16  is moved into place between the two side plates, end surfaces  60  of the roll  16  contact the tapered surface  44 , of each of the bearing members  34 , forcing the bearing members  34  to move outward, opposite the corresponding direction of arrow  57 . As the paper supply roll  16  is fully installed, the tapered surfaces  44  of the bearing members  34  move into a hollow cylindrical core  62  of the paper supply roll  16 , allowing the paper supply roll  16  to be snapped into place with the hollow cylindrical core  62  extending between the bearing support members  34 . 
     FIG. 6  is a fragmentary cross-sectional view of the receipt printer  10 , taken as indicated by section lines  6 — 6  in  FIG. 5 , particularly showing a pair of hook-shaped structures  64  holding each of the wire spring mounting structures  40  so against opposite sides  66  of the bearing member  34  and additionally holding the spring wire mounting structure  40  to push the bearing member  34  inward, in the direction of arrow  57 . 
   A second embodiment of the invention will now be discussed with particular reference being made to  FIGS. 7–9 .  FIG. 7  is a fragmentary side elevation of a receipt printer  70  showing a roll paper holder  72  built in accordance with a second embodiment of the invention.  FIG. 8  is a fragmentary cross-sectional view of the receipt printer  70 , taken as indicated by section line  8 — 8  in  FIG. 7 .  FIG. 9  is a perspective view of a bearing member  74  for holding the paper supply roll  16  within the receipt printer  70 , shown in an exploded relationship with a mounting structure  76  of one of the two side plates  78  within the printer  70 , in which the bearing member  74  is mounted. 
   In  FIG. 8 , the bearing member  74  is shown in an inward position, with a tapered surface  80  of the bearing member  74  extending into the hollow cylindrical core  62  of the supply paper roll  16 , so that the supply paper roll  16  is rotatably mounted between the tapered surfaces  80  of two bearing members  74  on opposite sides of the paper supply roll  16 . Again, the tapered surfaces  80  may be portions of spheres, as shown, or, for example, truncated cones. In a manner similar to that described above in reference to  FIG. 6 , this configuration provides for snap-in loading of the paper roll  16 . The bearing member  74  is held inward, in the direction of arrow  82  by a leaf spring  84  extending along the surface of the side plate  78 , being held in place by a pair of L-shaped structures  86 . 
   As shown particularly in  FIG. 9 , the bearing member  74  is slidably and pivotably mounted within a tubular portion  88  of the mounting structure  76 . The bearing member  74  includes a shoulder  90  having a pair of tabs  92  extending into a pair of slots  93  within the tubular portion  88  when the bearing member  74  is held in its inward position. As shown in  FIG. 8 , a space  94  is formed between the shoulder  90  and the tubular portion  88 , with the bearing member  74  in its inward position, when the paper roll  16  engages the tapered surface  80  of the bearing member. 
   The bearing member  74  is brought into its outward position by being pivoted in the direction of arrow  95  so that the tabs  92  of the shoulder  90  rest on the raised surface  96  of the tubular portion  88 , holding the bearing member  74  outward. A lever  98  is provided to facilitate the manual pivoting of the bearing member  74  in and opposite the direction of arrow  94 , between inward and outward positions. A detent bump  100  may be added to prevent inadvertent movement of the bearing member  74  from its outward position to its inward position. The movement of the lever  102  is further limited by contact with ribs  102  disposed in the side plate  78  at opposite sides of the mounting structure  76 . 
   While only one bearing member  74  has been shown and discussed in detail, it is understood that this bearing member  74  is exemplary of the two bearing members  74  mounted at opposite sides of the space provided for the paper roll  16  within the receipt printer  70 . Each of the two bearing members  70  has an axis  104 , about which rotation of the bearing member  74  occurs within the tubular portion  88 , with these two axes  104  being aligned with each other. 
   While the invention has been described in its preferred embodiments with some degree of particularity, it is understood that this description has been given only by way of example, and that many variations in the form and combination of parts may be made without departing from the spirit and scope of the invention, as defined in the appended claims.

Technology Category: b