Abstract:
A printer mechanism having a receptacle for receiving a printer cartridge therein. A print head is disposed in the receptacle, and a platen roller is rotatable about a roller axis. The platen roller is movable between a printing position in close proximity to the print head for urging labeling media and ink ribbon toward the print head and a nonprinting position in which the roller platen is spaced a distance from said print head to allow the labeling media and ink ribbon to be slipped therebetween. A platen roller gear is coaxial with said platen roller, and is engaged with a drive gear when the platen roller is in the printing position and disengaged from the platen roller gear when the platen roller is in the nonprinting position. A lever is linked to the platen roller, and is movable between a lock position and an unlock position. Movement of the lever from the unlock position to the lock position moves the platen roller from the nonprinting position to the printing position and extends the lever over the receptacle to lock a printer cartridge received therein.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     Not Applicable 
     Statement Regarding Federally Sponsored Research 
     Not Applicable 
     TECHNICAL FIELD 
     The present invention relates to a thermal transfer printer, and more particularly to a hand held thermal transfer printer having a cavity for receiving a printer cartridge containing labeling media and an ink ribbon. 
     DESCRIPTION OF THE BACKGROUND ART 
     There are a number of U.S. patents that disclose electronic apparatus for printing indicia on labels, some of these are restricted to hand held units and others that disclose tabletop units. Hand held labeling machines are disclosed, for example, in U.S. Pat. Nos. 4,264,396, Stewart; 4,407,692, Torbeck; 4,473,426, Goodwin et al.; 4,477,305, Hamisch; 4,490,206, Makely; 4,497,683, Hamisch; 4,498,947, Hamisch et al.; 4,511,422, Hamisch et al.; 4,544,434, Mistyurik; 4,556,442, Torbeck; 4,561,048, Hamisch et al.; and 4,680,078, Vanderpool et al. Tabletop units for this general purpose, some of which are portable are described in U.S. Pat. Nos. 4,440,248, Teraoka; 4,501,224, Shibayama; 4,630,538, Cushing; and 4,655,129, With et al. 
     The electronic machines for printing labels of the type disclosed above all include the same general combination of elements, a print head, means for feeding labeling media to be printed past the print head, a microprocessor, a read only memory programmed with appropriate instructions to operate the microprocessor, a random access memory, a keyboard with letter, number, and function keys for the entry of alphanumeric information and instructions concerning the indicia to be printed, and a visual display such as a LED, LCD unit to assist the operator in using the machine. In a hand held printer, these components may all be enclosed in a single housing. 
     The labeling media comprises a series of labels that are attached to a carrier strip. The carrier strip is fed through the printer and legends are printed on the labels. The labels are then removed from the carrier and attached to the objects needing identification. As there are many types of label applications, there are many combinations of labels and carrier strips that provide labels of varying sizes, colors and formats. 
     A particular type of print head employs thermal transfer printing technology. Thermal transfer printing uses a heat generating print head to transfer a pigment, such as wax, carbon black, or the like, from a thermal transfer ribbon to a labeling media. By using digital technology, characters are formed by energizing a sequence of pixels on the print head which in turn melt the wax or other pigment on the ribbon transferring the image to the labeling media. 
     In a known thermal transfer printer such as a label printer, labeling media is fed by a paper feed roller simultaneously with a platen roller feeding an ink transfer ribbon. While the labeling media driven by the feed roller runs between the print head and the rotating platen roller, the transfer ribbon is passed between the print head and the platen roller by rotating the platen roller. As a result, the labeling media and the transfer ribbon pass together in overlay relationship between the print head and the platen roller. 
     Loading the above printers with labeling media and an ink ribbon can be difficult and cumbersome. For example, known hand held label printers, such as disclosed in U.S. Pat. No. 5,165,806, include a cartridge containing both labeling media and an ink ribbon. The cartridge is inserted into a cavity formed in the printer body, and interfaces with the printer to print labels. The interface between the cartridge and the printer, however, is complex, and requires more than one step to lock the cartridge into the printer cavity and engage the printer with the cartridge in order to print labels. Accordingly, a need exists for a printer mechanism which provides a simple interface between a printer cartridge and a printer. 
     SUMMARY OF THE INVENTION 
     The present invention provides a printer mechanism having a receptacle for receiving a printer cartridge therein. A print head is disposed in the receptacle, and a platen roller is rotatable about a roller axis. The platen roller is movable between a printing position in close proximity to the print head for urging labeling media and ink ribbon toward the print head and a nonprinting position in which the roller platen is spaced a distance from said print head to allow the labeling media and ink ribbon to be slipped therebetween. A platen roller gear is coaxial with said platen roller, and is engaged with a drive gear when the platen roller is in the printing position and disengaged from the platen roller gear when the platen roller is in the nonprinting position. A lever is linked to the platen roller, and is movable between a lock position and an unlock position. Movement of the lever from the unlock position to the lock position moves the platen roller from the nonprinting position to the printing position and extends the lever over the receptacle to lock a printer cartridge received therein. 
     A general objective of the present invention is to provide a printer mechanism with a simple interface between a printer cartridge and the printer mechanism. This objective is accomplished by providing a printer mechanism and method of use which locks the printer cartridge in a receptacle in the printer, moves a roller platen into a printing position to sandwich labeling media and ink ribbon between the platen roller and a print head, and engages a drive gear with a stationary gear which rotatably drives the drive gear to rotate the platen roller, all in a single action of operating a lever. 
     The foregoing and other objectives and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims herein for interpreting the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a hand held label printer which employs the present invention; 
     FIG. 2 is a top view of the printer of FIG. 1 with the cartridge removed; 
     FIG. 3 is an exploded perspective view of the printer of FIG. 2; 
     FIG. 4 is a top perspective view of the cartridge of FIG. 1; 
     FIG. 5 is a bottom perspective view of the cartridge of FIG. 1; 
     FIG. 6 is a bottom view of the cartridge of FIG. 1; 
     FIG. 7 is a top perspective view of the cartridge receptacle of the printer of FIG. 2; 
     FIG. 8 is a bottom perspective view of the cartridge receptacle of FIG. 7; 
     FIG. 9 is a perspective view of the camshaft, cam and lever of FIG. 3; 
     FIG. 10 is an exploded perspective view of the cartridge receptacle and cutter mechanism of FIG. 3; 
     FIG. 11 is a detailed top view of the printer mechanism assembly of FIG. 3 with the platen roller in the nonprinting position; 
     FIG. 12 is a detailed top view of the printer mechanism assembly of FIG. 4 with the platen roller in the printing position; and 
     FIG. 13 is a front view of the printer of FIG. 1 with the lever in the lock position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring particularly to FIGS. 1-3, a thermal printing machine  10  which employs the preferred embodiment of the present invention includes a molded plastic housing  2  that supports a keyboard  4  on its front surface and a display  6  positioned above the keyboard  4 . An opening  8  formed in the housing  2  above the display  6  receives a cartridge  12  containing labeling media  14  and an ink ribbon  16  (shown in FIG.  6 ). The cartridge  12  is inserted through the opening  8  into a cartridge receptacle  18  housed in the printer housing  2 , and the labeling media  14  and ink ribbon  16  from the cartridge are threaded through a printer mechanism assembly  20  including a print head  22  and roller platen  24  for printing indicia on labels forming part of the labeling media  14 . The printed labels pass through a cutter mechanism  26  which cuts the labeling media to separate the printed labels from unprinted labels. 
     The labeling media  14  is known in the art, and generally comprises a carrier web which supports a series of adhesive labels. The size, width, color, and type of web material varies depending upon the particular print application. The labeling media is dispensed from the cartridge  12 , and urged along a web path as it is consumed by the printer  10 . 
     Referring to FIGS. 3-7, the cartridge  12  includes a cartridge housing  28  having a top wall  30  and a bottom wall  32  joined by periphery walls  34 ,  36 ,  38 ,  40 . The periphery walls  34 ,  36 ,  38 ,  40  define a semi circular labeling media container  42  and a rectangular ink ribbon container  44  joined to the labeling media container  42 . The top wall  30  extends past the periphery walls  34 ,  38 , and defines a printing area  46  outside of the housing periphery walls  34 ,  38  at the junction of the labeling media container  42  and ink ribbon container  44 . Labeling media  14  and ink ribbon  16  from inside the cartridge  28  housing pass through the printing area  46  for engagement with the roller platen  24  and print head  22 . A shelf  48  formed along one edge of the top wall  30  is flush with the printer opening  8  to allow engagement of the shelf  48  with a lever  50  which locks the cartridge  12  in the receptacle  18 . 
     The labeling media container  42  receives the labeling media  14  in the form of a roll. An exit slot  52  formed in the periphery wall  34  defining the labeling media container  42  opens into the printing area  46 , and provides an exit for the labeling media  14  and ink ribbon  16  to pass out of the cartridge housing  28  and into the printing area  46 . A projection  54  extending adjacent to the exit slot  52  guides the labeling media  14  and ink ribbon  16  as they exit the cartridge  12  through the exit slot  52 . 
     The ink ribbon container  44  extends tangentially from the semicircular labeling media container  42 , and has a proximal end  56  which opens into the labeling media container  42  and an opposing, closed, distal end  58  joined by the exterior periphery wall  36  which is a tangential extension of the labeling media container periphery wall  34 . The interior ink ribbon periphery wall  38  extending between the proximal and distal ends  56 ,  58  is spaced from the ink ribbon exterior periphery wall  36 , and defines a boundary of the printing area  46 . Ink ribbon  16  which has passed through the printing area  46  reenters the ink ribbon container  44  through an entrance slot  60  formed at the junction of the interior ink ribbon periphery wall  38  and the ink ribbon container periphery end wall  40 . 
     An ink ribbon supply spool (not shown) is supported between the top and bottom walls  30 ,  32  of the cartridge housing  28 , and has a roll of ink ribbon  16  wound thereon. The ink ribbon  16  is unwound from the supply spool, and passes out of the cartridge  12  with the labeling media  14  through the exit slot  52 . The ink ribbon  16  reenters the cartridge  12  through the entrance slot  60 , and is wound onto an ink ribbon take up spool (not shown). 
     The take up spool is supported between the cartridge housing top and bottom walls  30 ,  32 , and is rotatably driven by an ink ribbon drive shaft  62  which extends through an opening  64  formed in the cartridge bottom wall  32 . The shaft  62  engages the take up spool to rotatably drive the spool and wind the ink ribbon  16  thereon. 
     A labeling media guide  66  is formed at the ink ribbon container distal end  58 , and extends perpendicular to the interior ink ribbon periphery wall  38 . A guiding slot  67  formed in the guide  66  directs the labeling media  14  which is passed through the printing area  46  toward the cutter mechanism  26 . 
     Referring back to FIGS. 1-3, the cartridge  12  is received in the cartridge receptacle  18  housed in the printer housing  2 . The printer housing  2  is, preferably, formed from two halves  68 ,  70 , and houses printer components, such as the cartridge receptacle  18 , the keyboard  4 , display  6 , the cutter mechanism  26 , a printed circuit board  72  having printer circuitry, and the like. The opening  8  formed in the housing top half  68  provides access to the cartridge receptacle  18  for insertion of the cartridge  12  into the receptacle  18 . A slot  74  formed in the housing  2  adjacent the cutter mechanism  26  provides an exit for labeling media  14  (FIG. 6) which has passed through the cutter mechanism  26 . 
     Referring to FIGS. 6-12, the cartridge receptacle has a sidewall  76  generally shaped to conform with the cartridge periphery walls  34 ,  36 ,  38 ,  40 , and a floor  78  which supports the cartridge  12  therein. An eject mechanism  80  is formed as an integral part of the receptacle floor  78 , and includes a cantilevered arm  82  with a button  84  extending perpendicular to the arm  82  from the arm distal end  86 . The button  84  extends away from the receptacle floor  78  through the printer housing  2  (FIG. 2) for engagement by a user. The user urges the button  84  toward the receptacle  18  to engage the arm  82  with the cartridge  12  and push the cartridge  12  out of the receptacle  18 . 
     The printer mechanism assembly  20  is fixed to the printer receptacle  18 , and includes the stationary print head  22  and pivotable platen roller  24  mounted on a U-shaped frame  88 . The U-shaped frame  88  includes two upwardly extending legs  90 ,  92  joined by a base  94  (FIG.  2 ). One leg  90  has an inwardly facing surface  96  for mounting the print head  22  thereon. The opposing leg  92  has a distal end  98  with a tab  100  extending inwardly toward the one leg  90 . Preferably, the frame  88  is fixed to the receptacle  18  with screws  91 . However, any method known in the art for fixing a frame to another object, such as rivets, bonding, and the like, can be used without departing from the scope of the present invention. 
     The fixed thermal print head  22  is mounted to the inwardly facing surface  96  of the leg, and extends into the cartridge printing area  46  when the cartridge  12  is received in the receptacle  18 . The print head  22  cooperates with the ink ribbon  16  and the labeling media  14  such that the print head  22  can print characters or symbols on the labeling media. This is described in greater detail in U.S. Pat. No. 5,078,523 which is incorporated herein by reference. The labeling media  14  and ink ribbon  16  passing through the printing area  46  are advanced past the print head  22  by the platen roller  24  which maintains the ribbon  16  and labeling media  14  in close cooperation with the print head  22 . 
     The platen roller  24  is mounted on a roller shaft  102  which is rotatably fixed to an end  108  of a pivot linkage  104 . One end of the drive shaft  62  extends through the receptacle floor  78 . A drive gear  106  is fixed to the one end of the shaft  102 , and is coaxial with the platen roller  24 . The drive gear  106  engages a stationary gear  114  which is rotatably mounted to the underside of the receptacle floor  78 . The stationary gear  114  forms part of a gear assembly  116 , and meshes with the drive gear  106  to rotatably drive the platen roller  24 . 
     The pivot linkage  104  has an opposing end  110  pivotally fixed to a pin  112  supported between the frame tab  100  and base  94  (FIG.  2 ). The pivot linkage pivots  104  about the pin  112  to move the platen roller  24  between a printing position (shown in FIG. 12) and a nonprinting position (shown in FIG. 11) and to engage and disengage the drive gear  106  from the stationary gear  114 . A cam follower  111  extending from the pivot linkage  104  between the linkage ends  108 ,  110  engages a cam  118  to pivot the linkage  104  about the pin  112 . Although fixing the pivot linkage  104  to the pin  112  supported between the frame tab  100  and base  94  (FIG. 2) is disclosed, other methods for movably mounting the platen roller relative to the print head, such as slidably mounting the roller shaft in a slot formed in the housing and the like, can be used without departing from the scope of the present invention. 
     As shown in FIG. 12, when the pivot linkage  104  pivots to move the platen roller  24  to the printing position, the drive gear  106  engages a rotatably driven stationary gear  114  to rotatably drive the platen roller  24 , and the platen roller  24  extends into the receptacle  18  (FIG. 7) and urges the labeling media  14  and ink  16  ribbon against the print head  22 . In the nonprinting position shown in FIG. 11, the drive gear  106  is disengaged from the stationary gear  114 , and the platen roller  24  is spaced from the print head  22  to allow insertion of the labeling media  14  and ink ribbon  16  therebetween. 
     Referring to FIGS. 2-4,  8 - 12 , the cam  118  engages the pivot linkage  104  to move the platen roller  24  from the nonprinting position to the printing position and to engage and disengage the drive gear  106  with the stationary gear  114 . A spring  121  wrapped around one end of the pin  112  biases the linkage  104  against the cam  118  to bias the pivot linkage  104  away from the platen roller printing position. The cam  118  is fixed to a cam shaft  120  which is rotated about a cam shaft axis  113  by the lever  50  fixed to an end of the cam shaft  120  extending through the printer housing  2 . 
     The elongated lever  50  has one end  124  fixed to the cam shaft  120 , and is pivotable about the cam shaft axis  113  (shown in FIGS. 11 and 12) between a lock position (shown in FIG. 13) and an unlock position (shown in FIG.  1 ). Pivoting the lever  50  about the cam shaft axis  113  between the lock and unlock positions, rotates the camshaft  120  to engage and disengage the cam  118  from the pivot linkage  104 . Advantageously, in the lock position, the lever opposed end  127  extends over the receptacle  18 , and engages the top wall shelf  48  of the cartridge  12  to lock the cartridge  12  in the receptacle  18 . In the unlock position, the lever  50  is disengaged from the cartridge  12 , and allows the cartridge  12  into or out of the receptacle. Preferably, the lever  50  includes a rib  122  extending along a lever edge to provide an engagement surface for a user to easily engage the lever  50  to pivot it about the cam shaft axis  113 . 
     Referring back to FIGS. 7 and 8, the gear assembly  116  includes a plurality of intermeshed gears  114 ,  126 ,  128 ,  130 ,  132  rotatably mounted to the underside of the receptacle floor  78 . The gear assembly  116  is rotatably driven by a motor  134  fixed to the receptacle  18 . The motor  134  includes a shaft  136  which extends through the receptacle floor  78 , and has a pinion  138  fixed to the shaft  136  which meshes with the gear assembly  116 . The printer circuitry energizes the motor  134  to rotatably drive the shaft  136 , and thus the stationary gear  114 . 
     One of the plurality of intermeshed gears  132  is fixed to and coaxial with the ink ribbon drive shaft  62  which extends through the receptacle floor  78  to rotatably drive the ink ribbon take up spool. Advantageously, the gear assembly  116  simultaneously drives the platen roller  24  and ink ribbon drive shaft  62  to synchronize the operation of the platen roller  24  and ink ribbon take up spool to smoothly urge the ink ribbon  16  (FIG. 6) and labeling media  14  (FIG. 6) along the web path. 
     Referring to FIGS. 3-12, in use, the lever  50  is positioned in the unlock position which moves the platen roller  24  and drive gear  106  to the nonprinting position to retract the platen roller  24  away from the print head  22  and disengage the drive gear  106  from the stationary gear  114 . The cartridge  12  is then inserted into the cartridge receptacle  18 , such that the labeling media  14  and ink ribbon  16  in the cartridge printing area  46  slips between the print head  22  and platen roller  24 , and the ink ribbon drive shaft  62  engages the take up spool. 
     Once the cartridge  12  is inserted into the receptacle  18 , the lever  50  is pivoted about the camshaft axis  113  to extend over the receptacle  18  and engage the cartridge top wall shelf  48 , and thus lock the cartridge  12  in the receptacle  18 . Pivoting the lever  50  rotates the camshaft  120  and engages the cam  118  with the pivot linkage cam follower  111  to move the platen roller  24  and drive gear  106  into the printing position to sandwich the labeling media  14  and ink ribbon  16  between the print head  22  and platen roller  24  and engage the drive gear  106  with the gear assembly  116 . 
     Once the cartridge  12  is locked in place, the platen roller  24  is in the printing position, and the drive gear  106  is engaged with the stationary gear  114 , the printing machine  10  (FIG. 1) is ready to produce printed labels. When printing on the labels, the platen roller  24  and a take up spool advance the labeling media  14  and ribbon  16  through the printing area  46  past the print head  22 . When a desired character is input by an operator or other means, the electronics of the machine  10  energizes pixels on the print head  22  as the labeling media  14  and ribbon  16  advance past the print head  22 . The head pixels are variously energized to imprint the character on the labeling media  14 . This is described in greater detail in U.S. Pat. No. 5,078,523 which has been incorporated herein by reference. 
     The cartridge  12  is removed by pivoting the lever  50  to the unlock position which disengages the lever  50  from the cartridge  12  and moves the platen roller  24  to the nonprinting position and disengages the drive gear  106  from the stationary gear  114 . The cartridge  12  is ejected from the receptacle  18  by urging the eject mechanism button  84  towards the cartridge  12  to force the cartridge  12  out of the receptacle  18 . 
     While there has been shown and described what is at present considered the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention defined by the appended claims.