Abstract:
A platen assembly for a printer comprised of a platen roller assembly and a housing assembly that is structured to rotatably support the platen roller assembly. More particularly, the present invention is directed to a platen roller assembly comprising a platen roller defining first and second ends; a locking pin extending from at least one of the first and second ends of the platen roller; a housing assembly adapted to rotatably support the platen roller; and a drive assembly structured to rotatably engage the locking pin extending from one end of the platen roller. In this regard, the present invention provides a platen roller assembly that is simple, easily alignable, and readily replaceable by a user.

Description:
BACKGROUND OF THE INVENTION 
     1) Field of the Invention 
     Various embodiments of the present invention relate generally to an improved platen assembly for a printer and, more specifically, to a platen assembly that is structured for quick and efficient installation, removal, and/or replacement. 
     2) Description of Related Art 
     Platen rollers are widely used in printers to drive media against a printhead during printing operations. The platen roller provides a soft, often rubberized, surface for gripping and manipulating the media against the printhead. For print quality purposes, it is often important for the platen roller to apply a relatively constant and uniform pressure against the printhead along the full length of the platen roller. 
     Over the lifetime of a printer, platen rollers may need to be replaced due to abuse or normal wear and tear. If not replaced, a worn out or otherwise defective platen roller may provide uneven pressure against the printhead causing poor print quality or other problems. Accordingly, a need exists to ensure that worn or defective platen rollers, and any associated components, may be quickly and efficiently replaced. 
     For repeatable high quality printing, the printhead is closely aligned with respect to the printer platen. However, each time the platen is exchanged, the alignment between the printhead and platen is disturbed. Thus, a need exists to ensure that a replaced platen may be readily oriented in a fixed and aligned position relative to the printhead. 
       FIG. 1  depicts a printer structured in accordance with the known prior art. The printer  10  includes a printer housing  14  having a media door  12  that may be opened by a user to expose various internal printer components. In the depicted printer  10 , such internal printer components may include a media hanger assembly  13 , a platen assembly  20 , and a printhead assembly  40 . The media hanger assembly  13  may be a hanger as shown for supporting a spooled media such as adhesively backed labels. As is readily apparent to one of ordinary skill in the art, the media is drawn from a media supply spool (not shown) supported by the hanger assembly  13  and fed between the printhead assembly  40  and the platen assembly  20  during printing operations. The printhead assembly  40  may include a thermal demand printhead, an ink jet printhead, or other conventional printhead technologies. 
       FIG. 2  is a detail view of the prior art platen assembly  20  shown in  FIG. 1 . The depicted platen assembly  20  includes a platen housing  36  that defines first and second support members  38 ,  39  that are adapted to support a platen roller assembly  60 . The depicted platen roller assembly  60  includes a platen roller  21  and first and second clips  23 ,  24  for securing the platen roller  21  to the first and second support members  38 ,  39  at respective ends of the platen roller  21 . A drive shaft  22  is provided for connecting to a stepper motor (not shown) that is adapted to drive the platen roller  21  during printing operations. 
       FIG. 3  is an exploded view of a platen assembly  20  structured in accordance with the known prior art. As noted above, the platen assembly  20  includes a platen roller assembly  60  that is secured to a platen housing  36  by the first and second clips  23 ,  24 . The depicted platen roller assembly  60  includes a platen roller  21 , a drive shaft  22 , first and second support bearings  33 ,  34  disposed at opposite ends of the platen roller  21 , and a wave spring or washer  35  used in mounting the second support bearing  34  as shown. When the platen roller assembly  60  is installed in the housing  36 , the first and second support bearings  33 ,  34  are positioned within first and second support notches  31 ,  32  defined in the first and second support members  38 ,  39  of the housing  36 . 
     In many prior art applications, replacement of the platen roller  21  requires the application of several relatively complex steps. First, the stepping motor (not shown) must be loosened with a screwdriver or similar tool and disengaged from the platen roller assembly  60 . A drive belt (not shown) must then be removed from the disengaged stepping motor. Next, as suggested in  FIG. 2 , two flathead screwdrivers or other similar tools  5  are used to apply pressure to dislocate the barbed first and second clips  23 ,  24  from the first and second support members  38 ,  39  of the platen housing  36 . Once the clips  23 ,  24  are removed, the platen roller assembly  60  may be removed from the first and second support members  38 ,  39  of the platen housing  36 . 
     As will be apparent to one of skill in the art, it is typically quite difficult to manipulate screwdrivers or other tools within the tight confines of the printer housing. It also may be difficult to disassemble the drive assembly (e.g., stepping motor, drive belt, etc.). Thus, it would be desirable then to provide a platen assembly that may be quickly and simply installed and replaced without requiring the use of tools. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention addresses the above needs and achieves other advantages by providing a platen assembly comprised of a platen roller assembly and a housing assembly that is structured to rotatably support the platen roller assembly. More particularly, the present invention is directed to a platen roller assembly comprising a platen roller defining first and second ends; a locking pin or other drive element extending from at least one of the first and second ends of the platen roller; a housing assembly adapted to rotatably support the platen roller; and a drive assembly structured to rotatably engage the locking pin extending from one end of the platen roller. In this regard, the present invention provides a platen roller assembly that is simple, easily alignable, and readily replaceable by a user without requiring the use of tools or disassembly of the drive assembly. 
     In one embodiment, the platen assembly may be comprised of: a platen roller defining first and second ends; a locking pin or other drive element extending from at least one of the first and second ends of the platen roller; a housing assembly adapted to rotatably support the platen roller; and a drive assembly structured to rotatably engage the locking pin extending from at least one of the first and second ends of the platen roller. 
     First and second platen bearing assemblies may be disposed proximate the first and second ends of the platen roller respectively. In such embodiments, the first and second platen bearing assemblies may be adapted to be slidably received by the platen roller housing. More particularly, the housing assembly may comprise a first support member defining a first lock pocket and a second support member defining a second lock pocket, wherein the first and second platen bearing assemblies are adapted to be slidably received by the first and second lock pockets respectively. In some embodiments, the first platen bearing assembly may define a first key portion and the second platen bearing assembly may define a second key portion, wherein the first and second key portions are structured such that the first and second bearing assemblies are prevented from rotating upon being slidably received by the first and second lock pockets. 
     In still other embodiments, the platen roller may comprise a platen axle and the locking pin may comprise two prongs that extend from the platen axle. The drive assembly may comprise a drive coupler defining a central cavity and two drive notches for receiving the platen axle and the two prongs of the locking pin, respectively. In other embodiments, the locking pin may include three or more prongs that would correspond to three or more drive notches defined in the drive coupler as will be apparent to one of skill in the art in view of this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to ex-plain the principles of the invention. 
         FIG. 1  is an isometric view of a printer having a platen assembly structured in accordance with the known prior art; 
         FIG. 2  is a detail view of the prior art platen assembly shown in  FIG. 1 ; 
         FIG. 3  is an exploded view of the prior art platen assembly shown in  FIG. 2 ; 
         FIG. 4  is a printer having a platen assembly structured in accordance with one embodiment of the present invention; 
         FIG. 4   a  is a detail view of the platen assembly shown in  FIG. 4 ; 
         FIG. 5  is a detail view of a housing assembly for a platen assembly structured in accordance with one embodiment of the present invention; 
         FIG. 6  is a perspective view of a platen roller assembly structured in accordance with one embodiment of the present invention; 
         FIG. 7  is a detail view of a platen roller assembly oriented for engagement with a drive assembly supported by a housing assembly in accordance with one embodiment of the present invention; 
         FIG. 8  depicts a platen roller assembly being positioned for installation into a housing assembly in accordance with one embodiment of the present invention. 
         FIG. 9  depicts a platen roller assembly positioned for lateral insertion into the drive assembly and lock pockets of a housing assembly in accordance with one embodiment of the present invention; and 
         FIG. 10  is a perspective view of a platen roller assembly partially installed into a housing assembly in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout. 
       FIG. 4  depicts a printer  100  structured in accordance with one embodiment of the present invention. The depicted printer  100  comprises a printer housing  114  enclosing various internal printer components. Such internal printer components may be comprised a media support assembly  113 , a printhead assembly  140 , and a platen assembly  120 . The media support assembly  113  may be a hanger, as shown, for supporting a spooled media such as adhesively backed labels. As is readily apparent to one of ordinary skill in the art, the media is drawn from a media supply spool (not shown) supported by the media support assembly  113  and fed between the printhead assembly  140  and the platen assembly  120  during printing operations. The printhead assembly  140  may include a thermal demand printhead, an ink jet printhead, or any other known printhead technology. In some embodiments, the printhead assembly  140  may be rotated upwardly to expose the platen assembly  120  as shown in  FIG. 4 . In alternate embodiments, the printhead assembly  120  may slide laterally or may be simply removed to expose the platen assembly  120 . 
       FIG. 4   a  is a detail view of the platen assembly  120  shown in  FIG. 4 . The depicted platen assembly  120  is comprised of a housing assembly  136 , a latch assembly  145 , and a platen roller assembly  160 . The housing assembly  136  functions to support the platen roller assembly  160  within the printer  100  while the latch assembly  145  releasably secures the platen assembly  160  to the housing assembly  136  as discussed in greater detail below. 
       FIG. 5  is a detail view of the housing assembly  136  shown in  FIGS. 4 and 4   a , wherein the housing assembly  136  has been removed from the printer  100 . The depicted housing assembly  136  is comprised of a housing frame  180  having first and second support members  138 ,  139  each defining respective first and second support notches  131 ,  132 . The housing frame  180  may be made from a rigid polymer or metal such as aluminum. A drive assembly  150  is disposed at one end of the housing frame  180  proximate the first support member  138 . A latch assembly  145  is disposed at a second end of the housing frame  180  proximate the second support member  139 . 
     The depicted drive assembly  150  (which is shown in greater detail be  FIG. 7 ) comprises a drive housing  137  that partially encloses a drive bearing  153 , a drive shaft  122 , and a drive coupler  152 . In the depicted embodiment, the drive housing  137  is integrally connected to or part of the housing frame  180 . In alternate embodiments, the drive housing  137  may be removable from the housing frame  180  or may not be connected to the housing frame and secured to an adjacent printer component. 
     As will be apparent to one of skill in the art, the depicted drive bearing  153  allows the drive shaft  122  (and the drive coupler  152  connected thereto) to freely rotate relative to the drive housing  137 . In one embodiment, the drive shaft  122  may be connected to a stepping motor (not shown). In other embodiments, the drive shaft  122  may be connected to a direct current motor (not shown) or other device that is adapted to rotate the drive shaft  122  during printing operations. Various gear assemblies may be added in some embodiments to change the rotational speed of the drive shaft  122  relative to the rotational speed of the drive motor or other device. In various embodiments, the drive coupler  152  is structured to be releasably coupled to the platen roller assembly  160  for driving the platen roller  121  as discussed in greater detail with regard to  FIG. 7 . 
       FIG. 6  illustrates a platen roller assembly  160  structured in accordance with one embodiment of the present invention. The depicted platen roller assembly  160  comprises a first platen bearing  161 , a platen roller  121 , a second platen bearing  162 , a platen axle  163 , and a locking pin  164 . The depicted platen roller  121  defines a cylindrical body having a contact surface  121 ′ that is adapted to firmly and uniformly drive media against a printhead. In various embodiments, the contact surface  121 ′ may be made from a rubber or other similar material that is adapted to grip and compress media against a printhead during printing operations. The depicted platen axle  163  extends the full length of the platen roller assembly, through the platen roller  121  and the first and second platen bearings  161 ,  162 , as shown. The depicted first and second platen bearings  161 ,  162  are structured to allow the platen axle  163  (and platen roller  121 ) to freely rotate while securely fastened to the first and second support members  138 ,  139  of the housing frame  180  as discussed in greater detail below. 
       FIG. 7  is a detail view of a platen roller assembly  160  oriented for engagement with a drive assembly  150 , supported by a housing assembly  136  in accordance with one embodiment of the present invention. As noted above, the housing assembly  136  defines a first support member  138  having a drive assembly  150  mounted proximate thereto. The first support member  138  defines a first support notch  131  that is structured to receive the first platen bearing  161  of the platen roller assembly  160 . More particularly, in the depicted embodiment, the first support notch  131  defines a generally rectangular first bearing lock pocket  172  that is structured to slidably receive the first platen bearing  161  into a fixed or locked position. The depicted first platen bearing  161  defines a key portion  166  having a generally rectangular outer surface structured to be received in a fixed or locked engagement with the correspondingly rectangular inner surface of the first bearing lock pocket  172 . As will be apparent to one of ordinary skill in the art, the inventive concepts defined herein are not limited to platen bearings and lock pockets having rectangular shapes. Instead, these features may define any number of shapes (e.g., triangular, square, notched, round with radial projections, etc.) or key portions so long as they may be secured relative to one another in a fixed or locked position. 
     As noted above, the drive coupler  152  is adapted to receive and drive the platen axle  163  to rotate during printing operations. In various embodiments of the present invention, the platen axle  163  is configured to extend at least partially beyond the first platen bearing so as to be received within a central cavity defined by the drive coupler  152 . The drive coupler  152  further defines a first drive notch  155  and a second drive notch (not shown) about the perimeter of the central cavity for receiving a locking pin  164  disposed through the platen axle  163  as shown. Thus, once the platen axle  163  is seated within the drive coupler central cavity and the locking pin  164  is seated within the first and second drive notches, the drive coupler  152  is adapted to transfer its rotational motion to the platen axle  163  and thereby drive the platen roller  121  during printing operations. 
       FIG. 8  depicts a platen roller assembly  160  being positioned for installation into a housing assembly  136  in accordance with one embodiment of the present invention. As noted above, the housing assembly  136  comprises a housing frame  180  having first and second support members  138 ,  139  each defining respective first and second support notches  131 ,  132  that are structured to receive the platen roller assembly  160 . More specifically, the first and second support notches  131 ,  132  are adapted to securely receive the first and second platen bearings  161 ,  162  of the platen roller assembly  160 . Noting that the installation of the first platen bearing  161  was discussed generally with regard to  FIG. 7  above, the following discussion focuses on the installation of the second platen bearing  162 . 
     The depicted second support notch  132  defines a generally rectangular second bearing lock pocket  173  that is structured to slidably receive the second platen bearing  162  into a fixed or locked position. The depicted second platen bearing  162  defines a generally rectangular key portion  167  having first and second stop flanges  167 ′ extending laterally therefrom. The second platen bearing  162  is structured to be slidably received into a fixed or locked engagement with the correspondingly rectangular inner surface of the second bearing lock pocket  173 . Flange recesses  174  are defined at the lateral edges of the second bearing lock pocket  173  for receiving the stop flanges  167 ′ of the second platen bearing  162 . As was noted above, the present invention is not limited to rectangular platen bearings and lock pockets as depicted in  FIG. 8 . Rather, the inventive concepts provided herein may be applied to produce bearing/lock pocket arrangements having any number of shapes (e.g., triangular, square, notched, etc.) so long as they may be secured relative to one another in a fixed or locked position. 
       FIG. 9  depicts a platen roller assembly  160  positioned for lateral insertion into the drive assembly  150  and lock pockets of a housing assembly  136  structured in accordance with one embodiment of the present invention. The depicted platen roller assembly  160  is disposed in a first installation position wherein the first and second platen bearings  161 ,  162  are positioned laterally adjacent to their respective first and second lock pockets  172 ,  173  as shown. In one embodiment, the key portions  166 ,  167  of the first and second platen bearings  161 ,  162  are aligned with corresponding surfaces of the respective first and second lock pockets  172 ,  173  and the platen roller assembly  160  is moved laterally along arrow A to seat the bearings  161 ,  162  within the lock pockets  172 ,  173 . As will be apparent to one of skill in the art in view of this disclosure, in the depicted embodiment, the ends of the locking pin  164  are aligned with corresponding drive notches  155  of the drive coupler  152  before the platen roller assembly  160  is moved laterally to ensure that the locking pin  164  is properly seated within the drive coupler  152 . 
     Notably, the depicted drive coupler embodiment  152  includes two drive notches  155  corresponding to the two ends of the drive element or locking pin  164 . However, in alternate embodiments, differing drive element/drive coupler notch configurations may be used. For example, in one embodiment, the drive element could be a four pronged cross type structure that is configured to extend from one end of the drive axle. Accordingly, the drive coupler would be adapted to have four drive notches corresponding to each of the four drive element prongs. In another embodiment, the drive element could be a series of radially oriented projections extending from the platen axle that are adapted to be received by corresponding radially oriented notches defined by the drive coupler. Other similar configurations will be apparent to one of ordinary skill in the art in view of this disclosure. 
       FIG. 10  depicts a platen roller assembly  160  partially installed into a housing assembly structured in accordance with one embodiment of the present invention. The depicted platen roller assembly  160  is disposed in a second installation position wherein the first and second platen bearings  161 ,  162  are seated within corresponding first and second lock pockets  172 ,  173  defined by the first and second support members  131 ,  132  of the housing assembly  136 . In the depicted embodiment, the stop flanges  167 ′ of the second platen bearing  162  are structured to be received into the flange recesses  174  of the second lock pocket  173  thereby halting the lateral movement of the platen roller assembly  160  as discussed in relation to  FIG. 9  such that the platen axle and locking pin ends are seated properly into the drive coupler  152 . 
     Housing assemblies  136  structured in accordance with various embodiments of the present invention may also include a latch assembly  145  as shown. The depicted latch assembly  145  is comprised of a locking plate  142 , a spring plate  144 , and a pivot pin (not shown) that binds the locking plate  142  and spring plate  144  to the housing frame  180 . In various embodiments, the latch assembly  145  may be rotated from the generally horizontal “unlocked” position shown in  FIG. 10  to a generally vertical “locked” position along arrow B such that a recess (not shown) defined in the locking plate  142  of the latch assembly  145  slidably captures an extending end  163 ′ of the platen axle. In this way, the locking plate  142  is structured to prevent the platen roller assembly  160  from moving laterally or being removed from the first and second lock pockets  172 ,  173  when the latch assembly  145  is in the locked position. Although not particularly relevant to various embodiments of the present invention, the depicted spring plate  144  is used to secure the printhead assembly (not shown) in place for printing. 
       FIGS. 7-10  depict various steps associated with installation of a platen roller assembly into a housing assembly in accordance with various embodiments of the present invention. As will be apparent to one of ordinary skill in the art in view of this disclosure, the depicted platen roller assembly  160  may be removed from the housing assembly  136  by performing the depicted steps in a reverse order. For example, the platen roller assembly  160  may be removed by rotating the latch assembly  145  from a “locked” generally vertical position to an “unlocked” generally horizontal position; sliding the platen roller assembly  160  laterally in a direction opposite to arrow A of  FIG. 9  such that the first and second platen bearings  161 ,  162  become dislodged from the first and second lock pockets  172 ,  173 ; ensuring that the locking pin  164  and platen axle  163  are clear of the drive coupler  152 ; and then simply removing the platen roller assembly  160  from the housing assembly  136 . 
     Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the amended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.