Abstract:
A printer media cassette includes a movable arm which defines a desired path for media stock to facilitate insertion and removal of the cassette from a printer. The cassette also includes a tensioner arm for providing slack in the media path within the cassette to account for slippage between a feed roller of the printer and the media. Latching mechanisms on the cassette cooperate with latching mechanisms on a printer to assure proper installation of the cassette within the printer.

Description:
TECHNICAL FIELD 
     The present invention relates generally to printers and, more particularly, to a label stock cassette and label printer with features which aid installation and securing of the cassette into the printer, and improved label stock delivery during a printing operation. 
     BACKGROUND OF THE INVENTION 
     Label printers commonly utilize a media stock in the form of a roll of a backing material with labels affixed thereto, where the labels can be easily peeled from the backing material after passing by a print head assembly which prints information on the labels. In some printers media cassettes are used to supply the label stock, where the cassette includes a supply roll of label stock and a take up roll which receives a backing material of the label stock after labels have been printed and peeled therefrom. The label stock backing follows an angled path out of an opening in the cassette, around the print head assembly and back into the cassette to the take up roll. If the cassette is removed from the printer before the label stock supply is expended, reinsertion of the cassette is impeded by the need to attain the proper label stock path around the print head assembly. Accordingly, it would be desirable to provide a media cassette which facilitates placement of the label stock around the print head assembly upon insertion into the printer. 
     The label stock in such printers is typically fed past the print head by a rotatable feed roller which contacts the label stock and presses the label stock against the print head. In some situations, particularly where the supply roll of label stock is relatively large, when the feed roller first moves in order to begin movement of the label stock past the print head, the torque required to rotate the supply roll is sufficient enough to cause some slippage of the feed roller relative to the label stock. The result is typically seen as a compressed printed image on the label. Accordingly, it would be desirable to provide a media cassette which accounts for high torque loads generated by initial rotation of the supply roll. 
     As label stock cassettes get larger, installation and removal of the cassette becomes more difficult due to increased weight. It would therefore be desirable to provide a media cassette adapted for easier installation and removal, and it would also be desirable to provide a printer which is adapted for easier cassette installation, securing and removal. 
     SUMMARY OF THE INVENTION 
     In one aspect of the invention, a printer cassette installable in a printer includes a housing having a first media stock mount for positioning a roll of media stock thereon and a second media stock mount for holding a collection roll which receives a backing material of the media stock. An opening is provided in the housing, and an arm extends from the housing proximate to the opening for passing a loop of media stock therearound in position to be inserted into the printer along an intended path. The arm is biased into an extended position and retractable upon contact with a portion of the printer upon insertion of the cassette into the printer. Thus, the retractable arm locates the media stock in a proper orientation for being passed around the feed roller and stripper element of a print head assembly and therefor facilitates installation of the cassette into the printer. Various configurations of the arm are provided. 
     In another aspect of the invention, a printer includes a housing having a cassette receiving cavity, with a slot positioned along a peripheral surface of the cavity. A cassette latch member is positioned within the slot for holding a cassette within the cavity. A handle is connected with the latch member for effecting movement of the latch member. The latch member is movable between a latching position and a non-latching position, where the latch member extends from the slot into the cavity when in the latching position. The latch member is configured to engage a slot on the cassette when the cassette is inserted within the cavity. Preferably, the latch member includes a cam surface which cooperates with the cassette slot to pull the cassette into a secure position within the printer cavity. 
     In a further aspect of the present invention, a printer for printing labels includes a housing defining a cavity and a cassette positioned within the cavity, the cassette containing a supply roll of label stock. A print head assembly of the printer includes a label stock feed roller for feeding label stock past a print head of the assembly. A tensioner arm is positioned along a label stock path between the supply roll and the print head assembly. The tensioner arm contacts the label stock and is flexible to vary a label stock path according to a tension in the label stock during feed. The tensioner arm is positioned to for a normal label stock path which includes slack. When the torque required to move the supply roll and thus the tension of the label stock between the feed roller and the supply roll exceeds a certain level, the tensioner flexes or moves to allow the slack to be fed past the print head in order to reduce or prevent compressed printed images. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic side view of a printer and associated cassette; 
     FIG. 2 is a side view of one embodiment of a cassette according to the present invention; 
     FIG. 3 is a partial front perspective view of the cassette of FIG. 2; 
     FIG. 4 is a partial detailed view of one embodiment of a pivoting label path arm; 
     FIG. 5 is a partial detailed view of another embodiment of a pivoting label path arm; 
     FIG. 6 is a partial detailed view of one embodiment of a sliding label path arm; 
     FIG. 7 is a side view of the interior of a cassette; 
     FIG. 8 is a schematic view of a label path of the cassette of FIG. 7; 
     FIG. 9 is a side view of a printer; 
     FIG. 10 is a partial cross-sectional view of a printer with cassette inserted therein taken along line  10 — 10  of FIG. 9; 
     FIG. 11 is an enlarged view of one embodiment of a printer cassette latching mechanism; and 
     FIG. 12 is a partial top view of a bottom support surface of a printer cassette cavity. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 1, a schematic side view of a label stock cassette  10  installed within a printer  12  is shown. The cassette  10  includes a rotatable supply roll  14  of label stock and a take up roll  16  for receiving the backing which returns from a print head assembly  18  located near a front of the printer  12 . The print head assembly  18  includes a print head  20  for printing indicia on the labels which face downward, a feed roller  22  positioned above the print head  20  and biased against the print head  20 , and a stripper element  24  for causing labels to peel away from the label stock backing material. The labels  26  typically exit through a slot in the front of the printer housing as shown. A controller (not shown) controls movement of the feed roller  22  via a motor (not shown) and also controls movement of the take up roll  16  via a toothed belt drive (not shown) which is driven by the motor through an associated slip clutch (not shown). Alternatively, a separate control motor could be provided to drive the take up roll  16 . This set up depicted in FIG. 1 is generally known and illustrates the looped path which the label stock backing takes around the print head assembly  18 . This looped path can present cassette installation problems as mentioned above. 
     Accordingly, referring to FIG. 2, an improved printer cassette  30  is provided having a label path arm  32  for extending a loop  34  of the label stock therearound. As shown, the looped orientation of the label stock around the arm  32  corresponds to the loop the label stock takes around the print head assembly  18  when the cassette is installed in a printer  12 . In one embodiment, the arm  32  is L-shaped as shown in the partial perspective view of FIG.  3  and is pivotably mounted to a printer side  35  of the cassette housing  36 . Upon installation of the cassette  30  into a printer  12 , the arm  32  contacts a portion of the print head assembly  18  generating a force against the arm  32  as indicated by arrow  38 . In response, the arm  32  rotates or otherwise retracts inward toward the cassette housing opening  40  as indicated by arrow  42 , allowing the cassette to be inserted while at the same time providing a label stock path suitable to be passed around the feed roller  22  and the stripper element  24  of the print head assembly  18  as necessary. It is recognized that the label path arm  32  could contact some other structure within the printer to achieve the same result. For example, the printer housing might include a special ledge for contacting the label path arm  32 . The cassette  30  also includes a door  44  at its exterior side for enabling access to the interior of the cassette. 
     A more detailed depiction of one pivotable arm embodiment is shown in FIG. 4 where a partial front view of a cassette  30  is provided. A mounting bracket  50  connects to the cassette housing  36  at the printer side  35 . A pivot pin  52  extends downward from the bracket  50  to a point on the arm  32 . The pivot pin  52  is rotatably connected to the bracket  50  and fixedly connected to the arm  32 . A torsion spring  54  is positioned between the bracket  50  and the arm  32  around the pivot pin  52 , and includes an end segment which extends about a projection  56  extending upward from the arm  32 . The other end segment of the spring  54  engages the bracket  50 . The projection  56  acts as a torque application point of the arm  32 , with the torsion spring  54  urging the arm  32  into the illustrated extended position via its action on the projection  56 . A sufficient lateral force  38  against the side of the arm  32  acts against the torsion force of the torsion spring  54  and causes the arm  32  to rotate or pivot inward toward the front of the cassette  30 . The bracket  50  is preferably of a metallic material as are the pivot pin  52  and the projection  56 . The arm  32  is preferably of molded plastic construction. Also illustrated are a lower opening in the form of a slot  60  through which the label stock from the supply roll is fed from within the cassette  30  and an upper opening  62  for feeding the label stock backing material back into the cassette  30  and onto the take up roll. It is recognized that other pivotable arm arrangements are possible. A simplified variation would utilize a coil spring  70  having an end  72  which extends outward from the front of the cassette as shown in FIG.  5 . The interior end  74  of the coil spring  70  could be glued or otherwise secured to the cassette. The coil spring extension  76  acts as the label stock arm. Other pivot arm arrangements could be provided, including arrangement in which the arm pivots in a different direction. 
     While a pivotable arm may be preferred, non-pivoting arms could be utilized to achieve a similar result. Referring now to FIG. 6, a sliding arm  80  is illustrated extending from slot  82  at the front of a cassette  84 . The arm  80  may be spring-loaded outward and includes an angled surface  86  which acts as a cam surface when the cassette is inserted within a printer. In particular, the cam surface  86  contacts the feed roller of the print head assembly  18  or other portion of the printer and slides relative thereto so as to be pushed rearward into the slot  82 . It is recognized that other sliding arm configurations could be utilized. 
     An exemplary open cassette  30  is illustrated in FIG. 7 where the cassette door  44  is shown pivoted in the open position about its pivot axis  90 . The interior of the cassette body  92  includes a mount  94 , such as a boss, extending from the printer side of the body  92  for receiving a supply roll of label stock. The mount  94  includes a central opening  96 . A lower, forwardly positioned mount  98  is provided for a take up roll which receives the label stock backing, and the mount  98  is rotatable via interconnection with a shaft of a printer when installed therein. A central opening of a boss  100  forms a guide channel  102  for aid in positioning the cassette  30  within a printer via cooperation with a guide post extending from the printer cassette cavity. Boss  100  also serves as a guide for the backing paper to keep it away from other components in the cassette. 
     A label path  104  is shown in dashed lines and extends from the supply roll location under a tensioner arm  106  which extends from a guide plate  108  positioned above the bottom surface  10  of the cassette body housing. The guide plate  108  is rigidly mounted to the printer side of the body housing via fasteners  112 . As label stock supply rolls become larger, the feed roll torque needed to overcome the inertial force of the supply roll at rest increases and can cause the feed roller  22  of the printer to slip relative to the label stock. The tensioner arm  106  of the cassette  30  is intended to compensate for this problem by creating slack in the label stock path. In particular, referring to the schematic of FIG. 8, the tensioner arm  106  is shown in a normal position with label stock  104  extending thereunder. The tensioner arm flexes about the end of the guide  108  in the upward direction as indicated by arrow  114  when the tension in the label stock becomes large enough, and a shorter label stock path  104 ′ results. Accordingly, as the tensioner arm  106  moves the slack in the label stock path is fed in by the feed roller  22  reducing slippage of the feed roller relative to the label stock and therefore reducing or eliminating the compression of printed images that can result from such slippage. The tensioner arm  106  is preferably formed by an elongated thin, flexible metal sheet material, and may be adhesively connected to the underside of the guide plate  108  by, for example, a double sided adhesive tape or foam. 
     The cassette body also includes a latch member  120  in the form of a female portion of a latch stud, latch opening  122  combination. The latch member  120  is positioned on the printer side of the cassette body  92  for receiving a latch stud which extends from the printer. In this regard, reference is made to FIG. 9 where a side view of a printer  12  is shown. The housing of the printer  12  includes a cassette receiving cavity  130  formed in the side thereof. A support and guide stud  132  extends outward from an inner side of the cavity for positioning within the opening  96  of cassette mount  94 , and a guide stud  134  for positioning within the opening  102  of cassette mount  100 . The two guides facilitate sliding of a cassette into the cavity  130 . A latch stud  136  extends from the inner side of the cavity  130  for mating with the cassette latch member  120 . Drive shaft  137  for the take up roll of the cassette is also shown. The latching combination formed by stud  136  and member  120  is preferably of the press fit or snap fit type. For example, a cabinet style latch may be used. Stud  136  extends into the cassette as generally shown in the partial side view of FIG.  10 . 
     A bottom surface  138  of the cavity  130  is provided for resting the bottom of the cassette thereon as the cassette is slidingly inserted into the cavity  130 . The bottom surface  138  includes a slot or recess  140  formed therein with a latch member  142  positioned in the slot  140 . A handle  144  at the outer side of the cavity  130  pivots about point  146  where a shaft  148  extends from the handle  144  inward under the bottom surface  138  of the cavity  130  to the latch member  142  which rotates with the shaft  148 . The latch member is eccentrically connected to the shaft such that when the handle is in a horizontal or down position  150  the latch member is recessed in the slot  140  in a non-latching position and when the handle is in an upright position the latch member  142  extends from the slot  140  to provide a latching position. The bottom surface of the cassette housing/body includes a slot  152  positioned for alignment with the printer slot  140  so that when the latch member  142  extends through slot  140  and into cassette slot  152  for preventing the cassette  30  from sliding out of the cavity  130 . 
     As shown in the enlarged partial top view of FIG. 11, the latch member  142  preferably includes a cam surface  154  at its inner side for engaging a side edge of the cassette slot  152 . Thus, as the handle  144  is progressively rotated to the upright position the cam surface  154  contacts the side edge of the cassette slot  152  and pulls the cassette  30  into the cavity  130  against the inner surface of the cavity  130 . The inner surface of the cavity is formed by a fixed plate  156 . The shaft  148  extends inward past the latch member  142  and connects, via segment  148 ′, to a pivot block  158  located on the other side of fixed plate  156 . A compression spring  160  or other biasing member is positioned between the pivot block  158  and the fixed plate  156  (or some other fixed structure of the printer) and therefore biases the shaft  148  inward. Thus, the latch member  142  is also biased inward when engaging a cassette slot  152 . 
     As the handle  144  rotates to position  150 , a linkage mechanism which extends to the feed roller  22  can be used disengage the feed roller  22  from the print head  20  to provide an unobstructed path for the label stock loop to load or unload the cassette. 
     Referring again to FIG. 9, the front side  170  of the printer  12  includes a hinged door  172  having a slot  174  for allowing printed labels to pass therethrough. A label support surface  176  receives the printed labels. As best seen in the partial perspective view of FIG. 12, an extension spring  176  extends from the door to the printer  12  to bias the door  172  in the closed position. Alternatively, torsion biased hinges could be utilized. The door  172  provides access to the interior of the printer  12 , particularly to the print head assembly for maintenance and other adjustments and for cleaning. 
     Although the invention has been described above in detail referencing the preferred embodiments thereof, it is recognized that various changes and modifications could be made without departing from the spirit and scope of the invention. For example, while the foregoing description has been primarily with reference to label printers and label stock cassettes it is recognized that the various inventive features may have applicability to other types of printers and their associated cassettes and the therefore the scope of the invention is not intended to be limited to label printers and label stock cassettes unless otherwise specified in the claims which follow.