Abstract:
A printer for printing indicia upon media with print head and platen assemblies with ease of exchange and re-alignment features. The print head may be coupled to a print head bracket, the print head bracket removably coupled to the top cover of the printer by, for example, guide tabs of a print head support structure which mate with guide slots of the print head bracket. The print head bracket having alignment forks for aligning the print head with the platen. The printer also includes a platen bracket for maintaining the platen in the printer. The platen bracket being easy to remove to replace the platen.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   The present application claims priority from U.S. Provisional Patent Application No. 60/521,175 to Hirte et al., filed on Mar. 3, 2004, entitled: “Printer With Quick Release Print Head and Platen,” the contents of which are hereby incorporated by reference. 

   BACKGROUND OF INVENTION 
   1. Field of the Invention 
   The invention relates to printers, and more specifically, the invention relates to a cost effective printer having a print head and/or platen with improved alignment and ease of installation and removal of same. 
   2. Description of Related Art 
   Printers have been adapted for extended operation via increased media capacity. With media exchange delayed by the increased media capacity, ease of exchange and re-alignment of printer wear components has increased significance with respect to reducing overall printer downtime and operating costs. 
   Thermal print heads are a wear component. The individual thermal elements and or the media contact surface of the print head that encloses the individual thermal elements degrade with use, eventually requiring removal and exchange of the print head. 
   For repeatable high quality printing, the print head is closely aligned with respect to the printer platen. However, each time the media is exchanged, the alignment between the print head and platen is disturbed to allow loading of the media between them. 
   Prior printers have incorporated relatively complex and therefore expensive to manufacture and service print head to platen alignment mechanisms with spring loaded cams, levers and or multiple guide surfaces. Other printers may be designed to trade ease of re-alignment and overall alignment precision for lowered manufacturing costs. In addition to the mechanical linkages, the print head is typically keyed to the platen shaft by a pair of fork arms that engage the platen shaft. While the fork arms are useful for alignment along the platen longitudinal axis, they typically provide only a limited side-to-side alignment function. 
   The platen is also a wear component. Further, the platen may also be fouled by media jams and or damaged by untrained operators attempting to clear media jams with sharp objects that gouge and or cut the relatively soft platen roller material. Because the platen is typically gear driven, mounted directly to the printer frame and buried under the print head alignment structures, removal of the platen for cleaning and or exchange may require printer disassembly beyond the capabilities of the typical user. 
   Competition in the printer industry has focused attention upon improving ease of use and print quality while reducing manufacturing materials and operations costs. Therefore, it is an object of the invention to provide a printer that overcomes deficiencies in such prior art. 
   SUMMARY OF THE INVENTION 
   The present invention provides apparatus, systems, and methods for facilitating insertion and removal of print heads and platens (or other media rollers) from a printer. For example, in one embodiment, the present invention provides a bracket for retaining a print head in a printer. The bracket comprises a body extending between opposed ends and front and rear surfaces and at least one alignment structure adjacent to the front surface of the body for aligning the print head with a platen in the printer. The bracket further includes at least on retaining structure adjacent to the rear surface of the body for retaining the bracket in the printer and at least one hole extending through the body for receiving a pivot pin located in the printer chassis, wherein hole allowing the bracket to pivot laterally and the retaining structure allows the bracket to move vertically with respect to a platen located in the printer. In some embodiments, the hole is a slot defined in the body and extends from the rear surface of the body toward the front surface of the body. The pivot pin may include a retaining lip that engages the hole in the bracket to secure it to the printer chassis. 
   In some embodiments, the alignment structure includes a contact surface configured to contact at least one of the platen or a bushing associated with the platen. The alignment structure may comprise a fork having tines extending from the body of the bracket for engaging the platen. 
   The retaining structure can take various forms. For example, the retaining structure may be a detent that mates with a spring structure in the printer or vice versa. The retaining structure may alternatively comprise at least one guide slot that engages at least one guide tab associated with the chassis of the printer. 
   The present invention also provides various bracket configurations for retaining the platen or similar media roller in a printer. For example, in one embodiment, the present invention provides a bracket comprising a contact surface for engaging at least one of the platen or a bushing associated with the platen and at least one connector for securing the contact surface to a printer. In some embodiments, the bracket may include a biasing structure for biasing the connector against the printer to thereby retaining the bracket against the platen. 
   In some embodiments, the bracket comprises a body having a width extending between opposed first and second ends and a height extending between opposed third and fourth ends. The bracket comprises a respective contact surface adjacent to each of the first and second ends of the body. One of the contact surfaces defines a curved surface that extends from the body and the other of the contact surfaces is a curve surface defined in the body. 
   The present invention also provides systems for maintaining and allowing for removal of a platen from a printer. In one embodiment, the system comprises a retaining structure located in the printer comprising a first contact surface for mating with at least one of the platen or a bushing associated with the platen. The first contact surface comprises an opening to allow insertion and removal of the platen from the contact surface. The system also includes a bracket comprising a second contact surface sized to mate with the opening in the first contact surface of said retaining structure, where the second contact surface engages at least one of the platen or a bushing associated with the platen. The bracket further includes at least one connector for securing the bracket to the printer, wherein the first and second contact surfaces retain the platen in the printer. 
   The present invention also provides a print head alignment arrangement for use in a printer. The arrangement includes a print head coupled to a print head bracket having a first alignment pin and a second alignment pin. A bracket is located in the printer having first and second alignment holes, wherein upon insertion of the first alignment pin and the second alignment pin into the first alignment hole and the second alignment hole, respectively, the print head is aligned with a platen of the printer. 

   
     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, access doors closed, according to an exemplary embodiment of the invention. 
       FIG. 2  is an isometric right side view of the printer of  FIG. 1 , access doors open. 
       FIG. 3  is an isometric elevated left side view of the printer of  FIG. 1 , access doors open. 
       FIG. 4  is an elevated isometric view of the media loading area, media roll inserted, of the printer of  FIG. 1 . 
       FIG. 5  is an isometric bottom view of a print head, mounted upon the printer of  FIG. 1  according to one embodiment. 
       FIG. 6  is an isometric top view of the print head carrier assembly of the printer of  FIG. 1  according to one embodiment. 
       FIG. 7  is an elevated front isometric view of the platen and platen bracket, media omitted, of the printer of  FIG. 1  according to one embodiment. 
       FIG. 8  is an elevated front isometric view of the platen and platen bracket, media omitted and platen bracket removed, of the printer of  FIG. 1  according to one embodiment. 
       FIG. 9  is an isometric view of a platen bracket in the form of a tear bar according to one embodiment of the invention. 
       FIG. 10  is an isometric view of a platen bracket in the form of a peel bar according to one embodiment of the invention. 
       FIG. 11  is an isometric view of the platen bracket of one embodiment inserted into slots located in the chassis of the printer. 
       FIG. 12  is an elevated isometric view of the print head bracket according to an alternative embodiment of the present invention. 
       FIG. 13  is an isometric bottom view of a print head, mounted upon the printer of  FIG. 1  using the print head bracket of  FIG. 12 . 
       FIG. 14  is an elevated isometric view of the print head bracket of  FIG. 12 . 
       FIG. 15  is an elevated front isometric view of the platen and platen bracket located in the printer of  FIG. 1  according to one embodiment of the platen bracket. 
       FIG. 16  is an isometric view of the platen bracket of  FIG. 15 . 
       FIG. 17  is cut away isometric right side view of the platen bracket of  FIG. 15  engaging the platen. 
       FIG. 18  is cut away isometric left side view of the platen bracket of  FIG. 15  engaging the platen. 
   

   DETAILED DESCRIPTION 
   An exemplary embodiment of the invention, in the form of a printer  1 , including optional media liner rewind capability, is shown in  FIG. 1 . The printer  1  has two media access doors, a top door  3  and a front door  5 . The top door  3  may include a media window  7  through which an operator may quickly visually verify the presence, type and remaining volume of loaded print ribbon and or media  9 . 
   As shown in  FIGS. 2 and 3 , the top door  3  may be raised and the front door  5  lowered to access and or load the media  9 . The print head  11 , ribbon supply spindle  13  and ribbon take-up spindle  15  are attached to the top door  3 . When the top door  3  is opened, the print head  11  and ribbon spindles are raised up and away from the media supply path, allowing front-loading access of the media  9 . The media  9 , in the form of, for example, labels on liner material is supplied in bulk rolls of a desired roll width. The top door  3  is pivotably coupled to the frame  17  of the printer  1  at pivot point(s)  19  on either side of a media cavity  21 . The pivot point(s)  19  are selected to be at positions on either side of the media cavity  21  which allow the top door  3  to pivot open and allow insertion of the largest desired roll of media  9  usable with the printer  1 . Additionally, the top door  3  may be configured to pivot upwards to a position short of extending behind the printer  1  so that space behind, in addition to directly adjacent the perimeter of the printer  1  need not be available to enable printer operation and or media exchange. 
   To load media  9 , as shown in  FIG. 4 , the operator pushes a media  9  roll carried by a media spindle  27  along guide rails  23  to the back of the media cavity  21  where the media spindle drops into depression(s)  25  formed in the guide rails  23 . The media  9  may be centered between movable centering guides  29  which can be fixed in place via a spring lever  31 . The operator then lays a leader portion of the media  9  from the media  9  roll across the platen  33  and closes the top cover  3 , thereby sandwiching the media  9  between the print head  11  and the platen  33 , ready for print operations. 
   Returning to  FIGS. 2 and 3 , in instances where the media includes labels located on a liner, the printer includes a liner take-up reel  37  that may be mounted to the front door  5  to facilitate printer  1  front end access to the liner roll which accumulates upon the take-up reel  37  during on-demand operation, de-scribed herein below. If on-demand operation is not desired, the front door  5  and associated liner collection structure may be omitted. The liner take-up reel  37  incorporates a clip  39  adapted to receive and grasp an initial end portion of the liner. To allow the clip  39  to grasp a liner from media  9  of varying widths, the clip  39  extends the length of the take-up reel  37  and is biased towards a center of the take-up reel  37 . A ramp lever  41  is adapted for movement along a longitudinal axis of the take-up reel  37 . During movement away from the take-up reel  37 , the ramp lever  41  interacts with a ramp surface within the take-up reel  37  to also move radially inward with respect to the take-up reel  37 , thereby decreasing the effective diameter of the take-up reel  37  and allowing easy removal of the accumulated liner roll. A spring or the like is used to bias the ramp lever  41  into a steady state position of maximum take-up reel  37  diameter. During operation, the take-up real is driven via the gear  43 . 
   In this embodiment, the platen quick release bracket  35  operates as a tear bar having a tear edge  45  against which the user may tear off each printed label with the liner attached for later removal immediately prior to label application. Depending upon whether printer output in the form of a printed label with or without a liner attached is desired, the printer may alternatively be fitted with the tear bar or a peel bar  47  as shown in  FIGS. 5 and 6 . Instead of the tear edge  45 , the peel bar has a curved peel surface  49  which, as the liner is pulled across it, causes the forward edge of each label to separate from the liner, presenting a printed label to the user ready for immediate application. 
   In addition to providing structure that allows for ease in front loading of media and ribbon, the present invention also provides various systems and methods that allow for easy install and replacement of the print head and platen. Specifically, the present invention allows for easy replacement of the print head and platen in the field. This is important, where the life of the printer exceeds the useful life of the print head and platen, which require that such replacement be periodically made. Important considerations for infield replacement procedures are first that the procedure must be simple such that it can be performed with little or no training and second that replacement be time efficient, such that there is not significant down time for the printer. 
   In this regard, the present invention provides several different print head and platen configurations that allow for easy and quick replacement. For example,  FIGS. 5-9  illustrate a first quick release print head bracket and platen bracket design according to one embodiment of the present invention. 
   As shown in  FIGS. 5 and 6 , the print head  11 , supplied pre-mounted upon a print head bracket  51 , mates with a print head carrier structure  53  attached to the top door  3  of the printer. The print head bracket  51  to print head carrier structure  53  interconnection is adapted to permit quick print head  11  exchange without requiring the use of tools. 
   Specifically, retaining structures, such as a pair of guide tab(s)  55 , formed in the print head carrier structure  53  are adapted to mate with corresponding guide slots  57  formed in a forward edge of the print head bracket  51 . As the print head bracket  51  is inserted so that the guide tab(s)  55  mate with the guide slot(s)  57 , the print head  11  is loosely retained along a longitudinal axis of the guide slot(s)  57 . To retain the print head bracket  51  at a desired position upon the guide tab(s)  55 , a spring loaded pivot pin  59 , (see  FIG. 6 ), mates with a corresponding pin hole or slot  61 , (see  FIG. 5 ), formed in the print head bracket  51 . An electrical connector (not shown) is used to make the electrical interconnection between the print head  11  and the printer  1 . A loose lead cable allows the interconnection to be made before the print head bracket  51  is attached to the print head carrier structure  53 . 
   When mounted upon the print head carrier structure  53 , the print head bracket  51  is loosely retained, able to move and or pivot within a limited range defined by the fit of the pivot pin  59  within the pin hole/slot  61  and of the guide tab(s)  55  within the guide slot(s)  57 . To accommodate alignment variances that may be introduced by the large movement arm associated with the rear location of the pivot point(s)  19  relative the platen  33 , the loosely retained print head  11  is adapted for final self alignment upon closure of the print head  11  with the platen  33  as the top cover  3  is closed. 
   Specifically, to align the print head with platen, the print head of this embodiment further includes a pair of alignment pin(s)  63  projecting from the print head bracket  51 . These alignment pins mate with corresponding first and second alignment hole(s)  65 , 67  formed in the base of the printer, such as in the platen bracket  35 , as shown in  FIG. 7 . The peel bar  47 , described herein below, may also be used in place of the tear bar. Conical tapering of the distal ends of the alignment pin(s)  63  and or edges of the first and second alignment hole(s)  65 , 67  guides the print-head  11  into alignment with the platen  33  as the alignment pins initially engage the first and second alignment hole(s)  65 , 67 . To adapt for dissimilar thermal expansion coefficients and or lower the required component manufacturing tolerances, the second alignment hole  67  may be formed as an elongated slot. In this embodiment, the first alignment hole  65  sets the forward to back and left to right print head  11  alignment and the second alignment hole  67 , with reference to the first alignment hole  65 , sets the alignment of the print head  11  with respect to the longitudinal axis of the platen  33 . 
   As shown in  FIG. 8 , the platen assembly  69  is aligned with respect to the printer frame  17  via platen mounting surface(s)  71  that receive and support bearings, sleeves or other form of rotatable mounting surface(s)  75  located on the platen shaft  73  at either end of the platen. The rotatable mounting surfaces may be the platen itself or bushings on the platen. The platen  33  may be driven by, for example, a platen gear  77  located at one end of the platen shaft  73  that engages a driving gear (hidden from view) as the rotatable mounting surface(s)  75  seat against the platen mounting surface(s)  71 . 
     FIG. 9  illustrates one embodiment of a platen quick release bracket according to one embodiment of the present invention. The platen quick release bracket  35  is in the form of a tear bar in this embodiment. The bracket includes a body  83  extending between opposed ends  85   a  and  85   b . The body has a surface that extends substantially parallel to a laterally extending axis of the platen. The body includes one or more contact surfaces  79  adjacent to the opposed end of the body. (See also  FIG. 16 ). These contact surfaces  79  are structured to mate with either the platen itself or the rotatable mounting surface(s)  75  or other form of mounting surfaces associated with the platen. The bracket retains the rotatable mounting surfaces  75  via platen contact surface(s)  79   b  adapted to mate with a forward edge of the rotatable mounting surface(s)  75 . (See also  FIG. 16 ). 
   An aspect of the platen bracket is the ease with which it can be removed so as to allow access to the platen for repair or replacement. In this regard, the platen bracket includes one or more connectors, such as tabs  87 , for connection to the printer chassis. There are various structures and methods from securing the bracket. For example, as shown in  FIGS. 7 and 9 , the tabs may include holes extending through the tabs. The tabs may be connected to either pins, not shown, located in the printer chassis, or receive fasteners, such as for example, frame mounting screw(s)  81  that screw into the frame  17 . By removing the frame mounting screw(s)  81 , the platen bracket  35  may be easily removed and the platen assembly  69  released in a forward direction for cleaning and or exchange without further disassembly of the printer  1 . 
   In other embodiments, the bracket can be attached with either a minimum or no fasteners. For example, as illustrated in  FIG. 11 , the printer chassis may include slots  89  for receiving the tabs  87 . The bracket may include a biasing means, such as a spring, not shown, that biases the tabs with the slots. Alternatively, the bracket may sized slightly larger that the spacing of the slots and have a flexible structure that can be flexed to insert the bracket in the slot, whereby the body acts as a biasing structure. 
   While not illustrated, other embodiments of the bracket are envisioned. For example, the bracket could include hinge along its top edge for pivot connection to the printer chassis. This could be in the form of connector tab connected to the printer by a fastener. The bracket of this embodiment, includes a tab located at a bottom edge for fastening to the printer. Further, although the embodiments illustrated envision a bracket having a body that extends along the length of the platen, in some embodiments, the brackets could comprise one or clips located at either one or both ends of the platen for contacting and securing the platen in place. 
   For on-demand operation, the platen bracket is in the form of a peel bar  47 , as shown in  FIG. 10 , instead of a tear bar  35  and thereby the continuous liner, separated from each label by passage across the peel surface  49 , may be routed to the liner take-up reel  37  for accumulation and eventual removal during media exchanges. Otherwise, the platen bracket has the same print head  11  and platen assembly alignment and retention characteristics as the platen bracket in the for of a tear bar. When required, the print head  11  may be quickly exchanged by hand. The self-aligning print head  11  configuration reduces the overall printer complexity, removes potential failure points and reduces overall manufacturing cost. The simplified media path of a printer according to the invention reduces the opportunities for media jams. Should a media jam occur, ready access without pinch points upon opening of the top cover  3  and front cover  5 , if present, allows for quick recovery, reducing the chances that an operator attempting to clear the media path will damage the printer. The printer is adapted for removal of the platen assembly  69 , when required, by unskilled personnel using simple hand tools. The capability to easily remove the platen assembly from the front of the printer further reduces the overall downtime of the printer. 
   As mentioned, the configuration of the print head bracket and platen bracket discussed above allows for ease in removal and replacement. For example with regard to  FIG. 5 , to remove the print head, a user depresses the pivot pin  59 , such that the end of the pin clears the pivot pin hole  61  of the print head bracket. The user then pulls forward on the bracket so as to disengage the guide tabs  55  from the guide slots  57 . In the illustrated embodiment, the pin hole represents a hole in the bracket. In some embodiments, the pin hole may be a slot extending from a back end of the bracket. In this embodiment, the pivot pin  59  may include a retaining lip, such that when the pin is slid along the slot, the retaining lip engages and holds the bracket. (See  FIG. 13 ). 
   The platen can also be removed with similar ease. With reference to  FIG. 7 , the user can remove any fasteners retaining the platen bracket  35  and remove the bracket allowing access to the platen  33 . 
     FIGS. 12-15  illustrate an alternative embodiment for the print head bracket  51 . As illustrated in  FIG. 12 , the bracket of this embodiment includes a body  93  extending laterally between opposed first and second ends  94   a  and  94   b , and front  94   c  and rear  94   d  surfaces. Located near the rear surface  94   d  of the bracket  51  is a pivot pin hole  61 . The pivot pin hole  61  may be a hole through the plate. However, in some embodiments, the pin hole  61  defines a slot extending from the rear surface  94   d  to the front surface  94   c  of the bracket  51 . The pivot pin hole could also be a detent. Located adjacent the rear surface  94   d  of the bracket  51  is one or more bracket retaining structure(s)  95 . In the illustrated embodiment, the retaining structure is one or more detents. (The function of the retaining structure(s) is discussed later below.). The print head bracket  51  further includes one or more fasteners  97  for receiving and maintaining the print head, not shown, in the bracket. In addition, the print head bracket  51  also includes one or more alignment forks  99 . As will be discussed later, the aligning forks  99  engage the platen during operation to thereby align the print head with the platen. 
     FIG. 13  illustrates the installation of the print head bracket  51  in the printer  1 . The printer chassis includes a pivot pin  59 . The pin includes a body extending between opposed ends. A first or proximal end is connected to the printer chassis, while a second or distal end extends from the printer chassis for receiving the pin hole or slot  61 , see  FIG. 12 , of the print head bracket  51 . The pin may include a lip portion  101  located adjacent to the second or distal end of the pin. In this embodiment, the body of the pivot pin  59  is sized so as to fit within pin hole or slot  61 , while the lip portion  101  is sized somewhat larger than the pin hole or slot  61  to thereby retain the print head bracket to the chassis. 
   To assist in retaining the print head bracket, the printer chassis may further include retaining structure(s) to engage the retaining structure(s)  95 . For example, in one embodiment, either the retaining structure(s) of the printer chassis or the retaining structure(s)  95  of the bracket are spring structures and the other of the retaining structures. For example, in  FIG. 12 , the print head bracket  51  includes retaining structures in the form of detents  95 . These detents mate with spring structures located in the printer to thereby aid in retaining the print head bracket in the printer. While detents and corresponding spring structures are illustrated, it is understood that any number of different retaining structure configurations can be implemented. The retaining structures loosely maintain the bracket in the printer chassis and may allow the bracket to pivot vertically. 
   It is also noted here that in the above embodiments, the term printer chassis is used in a general manner when referring to connection of the print head bracket and platen bracket to the printer. The brackets may be connected directly to the chassis or to brackets, covers, etc. located in or attached to the chassis. 
   As illustrated in  FIGS. 14 and 15 , the print head bracket  51  further includes one or more forks  99 . The forks are typically adjacent to a front surface  94   c  of the print head bracket. The forks extend from a bottom surface of the bracket. The alignment forks include contact surfaces  103  for contacting the platen and aligning the print head with the platen. It is to be understood that the forks could be configures to contact the platen directly. However, as shown in  FIG. 15 , in some embodiments, the platen bracket includes bushings  105  that mate with the contact surfaces  103  of the platen bracket. As illustrated in  FIGS. 15 and 16 , the platen bracket  35  of this embodiment may be configured with openings  91  that allow the forks to pass therethrough and mate with the platen. 
   As illustrated, in operation, the print head bracket allows the print head to float relative to the bracket so as to properly align with the platen of the printer. Specifically, the retaining structures  95  retain the print head bracket  51  loosely in the printer chassis. The retaining structures allow the bracket move vertically with respect to the platen. Further, the pivot pin  59  allows the print head bracket  51  to pivot laterally, such that when the aligning forks contact the platen, the retaining structures and retaining pin allow for proper alignment with the platen both vertically and laterally. 
     FIGS. 15-18  illustrate an alternative embodiment to the platen bracket illustrated in  FIGS. 5-9 . Specifically, this bracket is designed allow the alignment forks  99  of the print head bracket illustrated in  FIGS. 12-15  to mate with the platen bar via slots in the platen bracket.  FIGS. 15-18  illustrate in greater detail the mating of the platen bracket with the platen. It is understood that the platen bracket of  FIGS. 5-9  will have a similar mating structure between the contact surface of the bracket and the platen. 
   As illustrated in  FIG. 15 , the platen bracket  35  of this embodiment is located in front of the platen and is connected to the printer chassis by one or more fasteners  97 . The platen bracket may include slots  91  for allowing access of the alignment forks  99  of the print head bracket to the platen. As illustrated in  FIG. 16 , the platen bracket  33  of this embodiment includes a body  107  having a width extending between opposed first and second ends,  109   a  and  109   b , and a height extending between opposed third and fourth ends,  109   c  and  109   d . The bracket includes connectors  87  for connecting the bracket to the printer. Further, the bracket includes one or more contact surfaces  79   a  and  79   b  located near the third end  109   c  of the bracket. The contact surfaces are generally curved so as to mate with either the platen or a bushing associated with the platen. As illustrated in the particular embodiment, one of the contact surfaces  79   a  may also be shaped to fit above the platen, while the other  79   b  engages a side of the platen. 
   The contact surface  79   a  of one embodiment extends from the body and comprises a curved surface, while the other contact surface  79   b  may be a curved surface formed in the body of the bracket. 
     FIGS. 17 and 18  illustrate the connection between the platen bracket and the platen. Specifically, the platen may include bushings  111 . The bushings are seated in a contact surface or retaining structure  113  located in the printer. The contact structure may be a hole in which the platen is inserted. The contact surfaces  79  of the platen bracket are sized to mate with the bushings  111 . When installed, the contact surfaces  79  of the bracket maintain the platen in proper place. As illustrated in this embodiment, the contact surface  79   a  is shaped to fit above the platen, while the contact surface  79   b  is shaped to engage a side of the platen. 
   While not shown, in some embodiments, the retaining structure  113  of the printer may be a curved structure having an opening for receiving the platen. The contact surface  79   a  of the bracket could fit within the opening in the retaining structure to thereby maintain the platen in place. 
   The above descriptions illustrate the use of the bracket with the platen roller of the printer. It must be understood that the bracket can be used with any roller in the printer and the term platen as used herein has a broader meaning such as to refer to any roller in the printer. 
   
     
       
             
           
             
             
           
         
             
                 
             
             
               Table of Parts 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
               1 
               printer 
             
             
               3 
               top door 
             
             
               5 
               front door 
             
             
               7 
               media window 
             
             
               9 
               media 
             
             
               11 
               print head 
             
             
               13 
               ribbon supply spindle 
             
             
               15 
               ribbon take-up spindle 
             
             
               17 
               frame 
             
             
               19 
               pivot point 
             
             
               21 
               media cavity 
             
             
               23 
               media guide rail(s) 
             
             
               25 
               depression(s) 
             
             
               27 
               media spindle 
             
             
               29 
               movable centering guides 
             
             
               31 
               spring lever 
             
             
               33 
               platen 
             
             
               35 
               platen bracket 
             
             
               37 
               take-up reel 
             
             
               39 
               clip 
             
             
               41 
               ramp lever 
             
             
               43 
               gear 
             
             
               45 
               tear edge 
             
             
               47 
               peel bar 
             
             
               49 
               peel surface 
             
             
               51 
               print head bracket 
             
             
               53 
               print head carrier structure 
             
             
               55 
               guide tab 
             
             
               57 
               guide slot 
             
             
               59 
               pivot pin 
             
             
               61 
               pin hole or slot 
             
             
               63 
               alignment pin 
             
             
               65 
               first alignment hole 
             
             
               67 
               second alignment hole 
             
             
               69 
               platen assembly 
             
             
               71 
               platen mounting surface 
             
             
               73 
               platen shaft 
             
             
               75 
               rotatable mounting surface 
             
             
               77 
               platen gear 
             
             
               79 
               platen contact surface 
             
             
               81 
               frame mounting screw 
             
             
               83 
               platen bracket body 
             
             
               85 
               platen bracket ends 
             
             
               87 
               platen bracket connectors 
             
             
               89 
               chassis slot 
             
             
               91 
               platen bracket slots 
             
             
               93 
               print head bracket body 
             
             
               94 
               print head bracket ends 
             
             
               95 
               print head bracket retaining structures 
             
             
               97 
               fasteners 
             
             
               99 
               alignment forks 
             
             
               101 
               pin lip portion 
             
             
               103 
               alignment fork contact surface 
             
             
               105 
               platen bushings 
             
             
               107 
               platen bracket body 
             
             
               109 
               platen bracket body ends 
             
             
               111 
               bushing 
             
             
               113 
               retaining structure 
             
             
                 
             
           
        
       
     
   
   Where in the foregoing description reference has been made to ratios, integers or components having known equivalents then such equivalents are herein incorporated as if individually set forth. 
   While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus, methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of applicant&#39;s general inventive concept. Further, it is to be appreciated that improvements and/or modifications may be made thereto without departing from the scope or spirit of the present invention as de-fined by the following claims.