Abstract:
A portable label printing system for printing on a variety of materials is disclosed. A retractable platen roller cooperates with a self-aligning print head in three planes cooperates for proper label printing registration. A display screen allows the user to view precisely what the actual label and associated indicia will look like when printed on a selected label. In addition, the printing system includes an optical sensor positioned to sense data marks on the backside of a label, located on a label supply roll, allowing the printing system to identify the label specifications and make necessary adjustments to affect print quality. Reverse feed of the label supply roll is possible. The label printing system further comprises a communication port for cooperation with various devices, such as online databases and computers.

Description:
RELATED APPLICATION 
   This application is a divisional of U.S. patent application Ser. No. 10/860,912, filed 4 Jun. 2004, now U.S. Pat. No. 7,040,822 which claims the benefit of Provisional U.S. Patent Application Ser. No. 60/475,659, filed 4 Jun. 2003. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to the art of hand-held printing systems and more particularly to a portable thermal label printing system that has improved functionality for ease of operation and print quality. 
   2. Brief Description of the Prior Art 
   There has been previously disclosed a number of hand-held printers and various stationary printers with the ability to print indicia on labels. Examples of such hand-held label printers have been disclosed in U.S. Pat. Nos. 4,807,177, Ward; 5,918,989, Stout, Jr. et al.; 5,951,177, Schanke et al.; and 6,113,293, Schanke et al. The electronic apparatus of the types disclosed above commonly include a general combination of elements including a print head, means for feeding a 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, a battery for portable power, and a visual display such as an LED or LCD display to assist the operator in using the apparatus. In a hand held printer, these components may all be enclosed in a single housing. 
   Prior art hand-held label printers require a user to manually input data pertaining to the label type to be printed. Although this provides the printer with the appropriate specifications to properly print the label, it also introduces the possibility of user error. Other prior art printers have incorporated the use of electronic components within the label support spindle to thereby identify the label specifications. This approach has reduced user error, but it has also increased the cost of manufacture, and increased the number of electronic components that could possibly fail. 
   In a thermal transfer printer such as a label printer, both the label supply roll and the ink ribbon pass together in overlay relationship between the print head and the platen roller. Typically, the print head and the platen roller are in fixed positions relative to each other. Printers of this type require the user to remove the ink ribbon and then delicately feed the label supply roll between the print head and the platen roller and within the printer for proper alignment and printing. This adds to the time and complexity of installing the label supply roll within the printer, and is compounded when a variety of label types are used. 
   Yet another deficiency in the art of hand held label printers is the ability to view an accurate representation of a designed label before the label is actually printed. As noted above, previous printers commonly incorporate a visual display such as an LED or LCD display to assist the operator in using the apparatus. The display allows visual confirmation of the indicia being applied to a label, but not a visual confirmation of the indicia being applied to a label relative to the label itself. This deficiency in the art creates wasted labels, as a user is required to print a sample label to confirm a proper label layout. 
   Also, many of these previously disclosed thermal printers have attempted to solve the problem of waste due to advancing the label supply roll and the ink ribbon by including a reverse feed function to enable recapture of these wasted portions. However, reversing the ribbon feed direction can introduce ribbon wrinkling and telescoping, which leads to misprinted labels and frustrated users. 
   Furthermore, prior art hand-held printers have had limited download capabilities. Previous printers have incorporated expensive interfaces to allow for data downloading or software upgrades, while other printers have had limited capabilities to communicate with a computer or an online database. These restrictions have limited the ability of hand held printers to remain current with the latest in label options, graphic images, user languages, and software. 
   Because of the foregoing deficiencies in the art, an object of the present invention is to provide a compact portable printing system that solves these problems by making the device easier to operate and simplifies the label design and printing process. 
   SUMMARY OF THE INVENTION 
   The present invention comprises a method and apparatus for printing labels and the like. Specifically, the present invention provides a novel handheld, easily transportable device that is capable of printing on supplied labels. Labels to be used with the present invention may be manufactured from a variety of materials, including, but not limited to paper, white and metalized polyester, vinyl, film, cloth, and tamper evident material, such as tamper evident vinyl. Additionally, labels to be used with the present invention may be of varying dimension and, if carried on a removable backing material, may be spaced relative to each other within a varying parameter. Labels having the various qualities mentioned also present varying printing requirements. Printing requirements of this type include variation in print head heat and label speed past a print head. By way of non-limiting example, labels made from vinyl require a lower print head heat than those made from polyester. As so to maintain superior print quality, the dwell time at the print head of the vinyl label is longer than the dwell time for the polyester label. 
   The apparatus of the present invention is uniquely adapted to receive the mentioned variety of label materials, detect particular incoming label material characteristics, adapt the printing head and label speed to those particular characteristics, and print on the label. Further, if labels to be printed according to the present invention are carried on a removable backing strip, the apparatus is adapted to detect label spacing and adapt print placement accordingly. 
   One novel feature of the apparatus according to the present invention includes a unique retractable platen roller arrangement that allows rolled labels to be easily changed without necessitating time consuming threading over spindles. The retractable platen roller arrangement includes a cover latching system and label guide bracket to assure proper registration of the platen roller with the print head. 
   Another novel feature of the present invention includes a unique, self-aligning print head. The novel print head includes means for self-alignment in three planes. This feature allows the print head to maintain a uniform pressure against a passing label and ink ribbon, and further cooperate with the retractable platen roller during printing. 
   There is also provided a unique chassis design that allows ink ribbon, such as thermal transfer ribbon, to be changed with minimal movement of apparatus parts to do so. The ribbon is preferably disposed within a ribbon cartridge housing having a configuration conforming to a complementarily shaped cavity in the chassis. The ribbon cartridge housing also preferably includes a ribbon supply spool and a ribbon take-up spool thereby organizing the ribbon cartridge in a compact unit. 
   A further unique feature of the present invention is the relationship between the display screen and the actual label print. The present invention allows a user to view the text or graphics to be printed via a conventional display screen. The display represents the print as it will appear with reference to a label. The apparatus is adapted to transfer the display image to a label in a true manner, such that the display screen represents the placement and relative size of the print to be printed on a selected label. This feature allows the user to view the actual label print layout and spacing prior to printing on the label. 
   The printing apparatus according to the present invention is further uniquely adapted to efficiently operate in both a forward and reverse label feed direction, thereby reducing label waste. The labels to be printed are fed in the direction of the print head and, after printing, are moved to a label tear off point. Printed labels dwell in the apparatus temporarily as they advance toward the tear off point. If a user wishes to change the print text and further capture all printed labels dwelling in the apparatus, the user may advance the labels such that all printed labels are moved past the tear off point. The label feed direction is reversed such that non-printed labels that have advanced past the print head and toward the label tear off point may be recaptured for subsequent printing. The apparatus is uniquely adapted to reduce ink ribbon waste and telescoping during reverse operation. 
   The apparatus is further adapted to cooperate with various input devices, such as online databases and computers. 
   The invention provides a convenient to use, compact arrangement for a hand held label printer. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a hand held portable printing system which embodies the present invention. 
       FIG. 1A  is a perspective view of the printing system in  FIG. 1  with the cover in an open, label spindle-receiving position. 
       FIG. 2  is a partially exploded perspective view of the printing system shown in  FIG. 1 . 
       FIG. 3  is a perspective view of the cover and print assemblies of the printing system shown in  FIGS. 1 and 2  in an open, label spindle-receiving position. 
       FIG. 4  is an exploded perspective view of the cover and print assemblies of  FIG. 3 . 
       FIG. 4A  is an exploded perspective view of the magnetic clutch assembly. 
       FIG. 4B  is a partially exploded perspective view showing the data mark sensing components and label cutting edge, with the optical sensor shown in phantom. 
       FIG. 4C  is an exploded top plan view of the label sensor plate and label guide bracket depicted to thereby show the relationship between the height dimension of the aperture in the label sensor plate and the height dimension of the raised portion of the label guide bracket, and the resulting height dimension of the slot when the label sensor plate is positioned on top of the label guide bracket. 
       FIG. 5  is a perspective view of the cover and print assemblies of  FIG. 2  in an open, label spindle-receiving position. 
       FIG. 6  is a perspective view of the cover and print assemblies of  FIG. 5  in an open position, and showing the label spindle with rolled labels in place. 
       FIG. 7  is a partially cut-away perspective view of the cover and print assemblies of  FIG. 2  in a closed, printing position, and showing the label supply spool path. 
       FIG. 8A  is a fragmentary cross section view taken along line  8 A- 8 A of the printing system in  FIG. 2 , showing the label supply roll and thermal transfer ribbon paths. 
       FIG. 8B  is a cross section view of the data marking sensing components and the optical sensor taken along line  8 B- 8 B of  FIG. 4B . 
       FIG. 9  is a side elevation view of the print assembly in an open position. 
       FIG. 10  is a side elevation view of the print assembly shown in  FIG. 9  in a closed position. 
       FIG. 11  is an exploded perspective view of an ink ribbon cartridge to be used with the present invention. 
       FIG. 12  is an exploded perspective view of the keyboard and display seen in  FIG. 1 , and showing relation to the control circuit board. 
       FIG. 13  is a perspective view of a reusable label spindle according to the present invention. 
       FIG. 14  is an exploded perspective view of the reusable label spindle of  FIG. 13 . 
       FIG. 15  is a top plan view of the printing system of  FIG. 1 , with a printed label ready for tear off and showing the relationship between what is viewed on the display and what is printed on a label. 
       FIG. 16  is a top plan view of the printing system of  FIG. 1 , similar to that of  FIG. 15 , and showing the relationship between what is viewed on the display and what is printed on a label, with a relatively small label being visible. 
       FIG. 17  is a fragmentary, top plan view of a carrier web with spaced-apart labels affixed thereto, with the reverse side depicted to thereby show the relationship between the data marks and the labels. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structure. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims. 
   Referring to the drawings, wherein like numerals represent like parts throughout the views, there is generally designated at  20  an ergonomically designed, hand held portable printing system according to the present invention. As seen particularly in  FIGS. 1 and 2 , the printing system  20  includes an upper housing  22  and a lower housing  38 . 
   The upper housing  22  supports a keyboard  24  on its front face and a graphic display  26  laterally spaced from the keyboard  24 . The unique alphanumeric keyboard  24  is preferably composed of an integrally formed, continuous elastomer membrane. This configuration prevents a control circuit board  48  ( FIG. 12 ) located below the keyboard  24  from getting damp or wet due to weather or spills. The keyboard  24  preferably extends the full length and width of the control circuit board  48  to provide maximum protection of the board  48 . 
   As best seen in  FIG. 12 , an ambient temperature sensor  200  located on the control circuit board  48  senses the ambient temperature and provides feedback to the control circuit board  48 . Based on the ambient temperature feedback received, the control circuit board  48  will adjust power output to the graphic display  26  and the print head  94  (shown in  FIG. 4 ) for optimal performance and operation. 
   The control circuit board  48  of  FIG. 12  also includes a processor and memory (not shown). Preferably, a processor used in conjunction with the printing system  20  is at least an eight-bit reduced instruction set computer (“RISC”) processor running at six megahertz, but any processor that will efficiently perform controls for the printing system is acceptable. The available memory on the control circuit board  48  preferably includes at least 128K of program storage, 128K of high-speed static RAM, and 256K bytes of flash non-volatile memory. The memory of the printing system  20  allows for the format of labels  54  ( FIGS. 15 and 16 ) to be saved and retrieved for future use. The mentioned 256K bytes of flash non-volatile memory preferably contains label formatting information, language, graphic images and other information that can be downloaded to the printing system  20  via an RS-232 communication port  25 , shown in  FIG. 12 . 
   The RS-232 communication port  25  enables the printing system  20  to download new label sizes, graphic images, and languages directly to the printing system  20  via a standard RJ45 phone jack from a standard computer (not shown). The communication port  25  can operate at any acceptable speed, preferably not greater than 19.2K baud. This new information can be downloaded off of an Internet site. Preferably, English is the default language, but other languages can be downloaded into the unit on demand at the discretion of the user. 
   Referring to  FIGS. 1 and 2 , the lower housing  38  includes a first side  41  having a cavity  39  formed therein for receiving a rechargeable battery  36 . An adjustable hand strap  35  may be attached to a bottom side  43  of the lower housing  38  for ease of handling. The ability of the printing system  20  to be powered by a rechargeable battery  36  makes the printing system  20  extremely portable and accessible. In a preferred embodiment, a NiCad battery  36  is utilized. The NiCad battery  36  preferably is adapted to use a standard adapter, such as a 120V, 230V, or 100V adapter (not shown), and may be fully charged within three to four hours. Removal of the rechargeable battery  36  in to and out of the printing system  20  allows for multiple batteries to be used. For example, as one battery is used in the printing system  20 , another battery may be charged for future use. A shock absorbent boot  32  covers the battery cavity  39  and provides protection for the hand held printing system  20  during field use. The boot  32  also provides a cover  33  for the RS-232 communication port  25 . 
   A novel feature of the present invention is the ability of the printing system  20  to print quality labels  54  (see  FIGS. 15 and 16 ) until the battery  36  loses charge. Preferably, an algorithm is built within the control circuit that senses the charge of the battery  36  and causes the battery  36  to work harder to print as the power of the battery  36  degrades over time, which ensures that there is no change in print quality over the life of the battery  36 . Only the last printed label would have degradation of quality. The printing system  20  has further been adapted to display the amount of battery life left on the graphic display  26 . 
   As best seen in  FIGS. 12 ,  15 , and  16 , the graphic display  26  is preferably comprised of a display lens  42  and a LCD display  44 . The display  44  may be a 2.0″×1.5″ viewable graphics LCD display, preferably containing 128×64 pixels. The LCD display  44  is capable of showing multiple font sizes, for example, small, medium, and large, with the sizes being relative to the size of the specific label  54  being selected and displayed. A virtual font feature allows the software to determine what is small, medium, and large. A maximum of 20 characters can be displayed and printed on a 1″ (25.4 mm) or 2″ (50.8 mm) wide label. In a preferred embodiment, the contrast of the LCD display  44  may be manually adjusted. 
   As viewed in  FIGS. 15 and 16 , a series of “Softkeys”  210  appear on the graphic display  26  and change depending on the currently selected editing mode. Pressing a corresponding button  209  activates the specific softkey function. The activated function appears directly above each button  209  the graphic display  26 . This novel softkey feature eliminates the total number of keys on the keypad  24  and allows easy editing and minimization of help screens and menus. 
   With further reference to  FIGS. 15 and 16 , it may be seen that the label editing may be considered “WYSIWYG” (what you see is what you get). The software used in conjunction with the present invention is adapted to provide a virtual image of the label  54  on the graphic display  26 , thereby allowing the display  26  to show the user what will print on a selected label  54 . The currently edited line preferably shows a flashing cursor (not shown) below it. 
   As viewed in  FIG. 2 , the lower housing  38  further supports a print assembly  40 . The print assembly  40  houses a reusable label spindle  34  and an ink ribbon cartridge  30 . As seen particularly in  FIG. 14 , the reusable label spindle  34  includes a label supply roll  55  which may include a carrier web  53  with adhesively backed labels  54  attached thereto. A cover assembly  28  encloses the label spindle  34  and is pivotally mounted to the print assembly  40 . The novel design of the pivotally mounted cover assembly  28  and the print assembly  40  allows loading and unloading of the reusable label spindle  34  and label supply roll  55  easier and quicker than in previous printers. The label supply roll  55  having labels  54  carried thereon is loaded onto the reusable spindle  34  (see  FIG. 14 ). The spindle  34  is inserted into the printing system  20 , and the label supply roll  55  is pulled over the top of the spindle  34 , similar to the process of loading film into a camera, and the cover assembly  28  is closed. The design alleviates the time consuming requirement of mechanically feeding and aligning the label supply roll throughout the printing system  20 . 
   Label Supply Roll 
   Referring now to  FIGS. 7 and 14 , the label supply roll  55  comprising the carrier web  53  carrying the adhesive labels  54  is shown. The size and type of the label material carried by the reusable label spindle  34  varies depending on the particular print application. Although adhesive labels  54  carried on the web  53  are shown, it is to be understood that the printing system  20  may also print on other material, such as, for example, shrink wrap (not shown). As the printing system  20  consumes the label supply roll  55 , it unrolls off the label spindle  34  until the label spindle  34  is empty. The back side  192  of the carrier web  53  preferably includes data marks or other information that is optically readable, such as the barcode  194  shown in  FIG. 14 , for identification of label  54  specifications including type, size, print head heat, print speed, and label distance from one label to the next. The novel barcode  194  identification means eliminates the need for other more expensive means for label identification. 
   Referring now to  FIG. 17 , and by way of non-limiting examples, an edge  193  of the label  54  begins at a predetermined point A after the end  195  of the barcode  194 . In a preferred embodiment, the edge  193  of the label  54  begins 1.12″ after the end  195  of the barcode  194 . In addition, the barcode  194  is of a predetermined width, B and repeats as often as possible, while maintaining a minimum predetermined distance C between barcodes  194 . The width B would be 1.122″ wide and the minimum distance C would be 0.20″, although other suitable widths B and distances C may be used. 
   Ink Ribbon Cartridge 
   Referring now to  FIGS. 2 and 11 , an ink ribbon cartridge  30  having thermal transfer ribbon  66  disposed within a ribbon cartridge housing  62  is shown. The ink ribbon cartridge  30  is inserted into a cavity  77  in the side of the printing system  20  and is further received and supported by a drive cog  160  ( FIG. 3 ). The drive cog  160  provides automatic radial alignment during insertion into the cavity  77 . The ribbon cartridge housing  62  is attached to a ribbon cartridge door  74  by any conventional means, such as in this embodiment, a screw  60  and cartridge door tabs  71 . Each tab  71  on the cartridge door  74  preferably includes an aperture  73 . The ribbon cartridge housing  62  further includes a mating portion  61  that snaps into a corresponding aperture  73 . The ribbon cartridge door  74  includes a door latch  76  for securing the ink ribbon cartridge  30  within the ribbon cartridge cavity  78 . In a preferred embodiment, a supply spool  59  for thermal transfer printing onto the label  54 , and a take-up spool  58  for taking up the ribbon  66  after being used in the thermal transfer printing process, are accommodated within the ribbon cartridge housing  62 . The supply spool  59  is supported within the ribbon cartridge housing  62  by supply spool keys  63  and  65 , which are inserted into the ends of the supply spool  59 . A thrust washer  69  is inserted into the supply spool key  65 , which in conjunction with a thrust spring  70  seated on the ribbon cartridge door  74 , prevents telescoping of the ribbon  66  and provides positioning and proper tension during winding. Similarly, the take-up spool  58  is supported within the ribbon cartridge housing  62  by a take up spool key  64 , which is inserted into a first end of the take-up spool  58 . A door spring  72  seated on the ribbon cartridge door  74 , in conjunction with spacer washer  68 , located between the door spring  72  and the take-up spool  58 , provides positioning and proper tension during winding for the take-up spool  58 . 
   As best seen in  FIG. 1A , the design of the printing system  20  allows the ribbon cartridge  30  to remain in the printing system  20  while changing the label spindle  34 . This feature saves time for the user and reduces the chance of damage to the printing system  20  or the ink ribbon cartridge  30 , since the ribbon cartridge  30  does not have to be removed when during the spindle  34  changing process. Furthermore, the provided ribbon  66  (see  FIG. 11 ) is preferably of a greater overall length than the current industry standard, which translates into fewer ribbon cartridge  30  changeovers, again reducing the chance for damage to the printing system  20 . 
   Print Assembly 
   Referring now to  FIGS. 4 ,  7 , and  8 , a print head  94  is disposed within the print assembly  40 . In a preferred embodiment, the print head  94  is a 203 dpi thermal transfer print head, although other print heads  94  may be used. The print head  94  is positioned to cooperate with the thermal transfer ribbon  66  and the label supply roll  55  such that the print head  94  can print characters or symbols on the adhesive labels  54  as the label supply roll  55  moves along a preselected path within the print assembly  40 . 
   More specifically, and as is best seen in  FIG. 4 , the print head  94  is mounted to a stabilizer bracket  96  by conventional means, such as the two screws  98  shown. The stabilizer bracket  96  preferably includes two slots  99  to allow for position adjustment of the print head  94 . A tension bracket  104  mounted to a print head chassis  144  by way of two screws  106  provides support for the print head  94 . Two print head support tension springs  152  are positioned between the stabilizer bracket  96  and the tension bracket  104  to provide for up and down or elevational alignment of the print head  94  with respect to the preselected path of the label supply roll  55 . Slots  97  in the stabilizer bracket  96  provide for left and right alignment of the print head  94 , or transverse alignment with respect to the preselected path of the label supply roll  55 . The print bracket spindle  102 , in conjunction with a print head alignment compression spring  100 , provides the spatial relationship, including left and right alignment, between the tension bracket  104  and the stabilizer bracket  96 . Print head alignment pins  95  coupled into label guide bracket yokes  83  provide for aft alignment, or directional alignment along with the preselected path of the label supply roll  55 . The combination of the tension springs  152 , the slots  97  in the stabilizer bracket  96 , and the print head alignment pins  95  provide for a self-aligning print head  94  in three directions. The print head chassis  144  is mounted within the upper housing  22  and lower housing  38  of the printing system  20 , as shown in  FIG. 2 . 
   Magnetic Clutch 
   In order to eliminate the need to reverse the direction of the ink ribbon cartridge  30  ( FIG. 1 ) when the direction of the label supply roll  55  ( FIG. 7 ) is reversed, a magnetic clutch assembly  114 , shown in  FIG. 4A , provides for advancement of the thermal transfer ribbon  66  past the print head  94  while printing, yet does not allow the ribbon  66  to reverse its direction while the label supply roll  55  is reversed, as can be seen in  FIG. 8 .  FIG. 4A  shows a rare earth magnet  165  seated within a clutch gear  164 . The clutch gear  164  is mounted on a spool drive spindle  161 . The spool drive spindle  161  is inserted through a rear ribbon bushing  162 , which is positioned within the print head chassis  144 . A clutch disk  166  is positioned between the clutch gear  164  and a clutch ratchet  168 . The clutch ratchet  168  is secured to the spool drive spindle  161  by a setscrew  170 . A clutch pawl  174  is maintained in close relation to the clutch ratchet  168  by a pawl spring  176 . The clutch pawl  174  and the pawl spring  176  are mounted on a shoulder screw  172 , which is secured to a cage support tube  116 . 
   Gear Mechanism 
   Referring now to  FIGS. 4 ,  9 , and  10 , a stepper motor  112  mounted in the print head chassis  144  engageably drives a bi-directional stepper motor gear mechanism  121 . The stepper motor  112  includes a four-pin connector  113 , adapted for connection to a mating receptacle (not shown) on the control circuit board  48 . The remaining details of the exterior of the circuit board are shown in  FIG. 12 . The gear mechanism  121  is mounted on the print head chassis  144 . The gear mechanism  121  drives the platen roller gear  92  and the magnetic clutch assembly  114 . Slots  119  located in an adjustable gear plate  118  allow for adjustment of the alignment of gear  136  and gear  130 , in relation to the magnetic clutch assembly  114  and gear  124 , respectively. The magnetic clutch assembly  114  in turn rotatably drives the take-up spool  58  of the ink ribbon cartridge  30  to take up and supply the thermal transfer ribbon  66  past the print head  94 , as seen in  FIG. 8 . Also with reference to  FIG. 8 , it may be seen that the label supply roll  55  and ribbon  66  are advanced past the print head  94 . The platen roller  91  maintains the ribbon  66  and the label supply roll  55  in close cooperation with the print head  94 . 
   More specifically, and as viewed on  FIGS. 4A and 10 , the stepper motor  112  (see  FIG. 4 ) rotates in a first direction, thereby rotating drive gear  122  in a counter clockwise direction. Drive gear  122  in turn engages and rotates gear  124  in a clockwise direction. Gear  124  engages and rotates gear  130  in a counter clockwise direction, which engages both gear  136  and platen roller gear  92 . The counter clockwise rotation of gear  130  causes both gear  136  and platen roller gear  92  to rotate in a clockwise rotation. Gear  136  engages the clutch gear  164  of the magnetic clutch assembly  114  (see  FIG. 10 ). The magnetic clutch assembly  114  allows the clutch gear  164  to rotate in a counter clockwise direction. The magnetic force of the rare earth magnet  165  seated within the clutch gear  164  causes the clutch ratchet  168  to rotate in a counter clockwise direction, which also causes the drive cog  160  to rotate in a counter clockwise rotation. The drive cog  160  in turn rotatably drives the take-up spool  58  of the ink ribbon cartridge  30  to take up and supply the thermal transfer ribbon  66  past the print head  94  along the transfer ribbon path  67  ( FIG. 8 ). Concurrently, the counter clockwise rotation of gear  130  causes clockwise rotation of platen roller gear  92 , thereby causing the platen roller  91  to rotate in corresponding clockwise direction. The clockwise direction of the platen roller  91  urges the label supply roll  55  to advance past the print head  94  along the label supply roll path  89  ( FIG. 8 ). As previously stated, the platen roller  91  maintains the ribbon  66  and the label supply roll  55  in close cooperation with the print head  94 . 
   When the stepper motor  112  is rotating in an opposite direction, drive gear  122  rotates in a clockwise direction. Drive gear  122  in turn engages and rotates gear  124 , which in turn engages and rotates gear  130  in a clockwise direction. Gear  130  again engages both gear  136  and platen roller gear  92 , causing both gear  136  and platen roller gear  92  to rotate in a counter clockwise rotation. Gear  136  engages the clutch gear  164  of the magnetic clutch assembly  114 . The magnetic clutch assembly  114  allows the clutch gear  164  to rotate in a clockwise direction. The magnetic force of the rare earth magnet  165  seated within the clutch gear  164  attempts to cause the clutch ratchet  168  to rotate in a corresponding clockwise direction, but the clutch pawl  174  engages the clutch ratchet  168  to restrict clockwise rotation of the clutch ratchet  168 . The restriction of clutch ratchet  168  further restricts rotation of the drive cog  160 . The take-up spool  58  of the ink ribbon cartridge  30  remains in a non-rotating state while the clutch gear  164  rotates in a clockwise direction. The thermal transfer ribbon  66  remains stationary at the print head  94  ( FIG. 8 ). At the same time, the clockwise rotation of gear  130  causes platen roller gear  92  to rotate in a counter clockwise rotation. Platen roller gear  92  causes the platen roller  91  to rotate in a corresponding counter clockwise direction, which urges the label supply roll  55  to reverse past the print head  94  and recoil on the label spindle  34 . This bi-directional label supply roll  55  feeding feature automatically feeds the label supply roll  55  forward for printing and severing of the label supply roll, and then allows for a reverse feed in order to be able to use all the labels  54  on the label supply roll  55 . 
   Cover Assembly—Optical Sensor 
   Now referring to  FIG. 4 , a cover assembly  28  may be seen to include a lid  186  and a cover chassis  90 . The cover assembly  28  is pivotally attached to the print assembly  40 , by way of a pivot axle  156  secured in place by c-clips  154 . The pivot axle  156  is partially positioned within a pivot axle spacer  142 . Additional spacers  188  and  190  may be positioned over the pivot axle  156  between the cover chassis  90  and the print head chassis  144 .  FIG. 5  shows a stop pin  202  mounted to the cover chassis  90 . The print head chassis  144  preferably includes an oblong slot  204  formed therein, which receives the stop pin  202  and defines the extent to which the cover assembly  28  is allowed to pivot. 
   As best seen in  FIG. 4 , the cover assembly  28  preferably includes an optical sensor  86 , secured to a label guide bracket  84  by way of screws  85  or other conventional means. The optical sensor  86  reads data marks, such as the barcode  194  shown in the Figures and located on the back side  192  of the carrier web  53  (see  FIG. 14 ). As mentioned, barcode  194  or other data marks supply information to the printing system  20  such as identification of label specifications including type, size, print head heat, print speed, and label distance from one label to the next. The label guide bracket  84  is further secured to the cover chassis  90  with screws  88  or other conventional means. 
   Referring to  FIGS. 4B ,  4 C, and  8 B, the label guide bracket  84  includes a slotted window  81  and a partial circular raised portion  79 , which has an edge that terminates at a mating edge of the slotted window  81 . The raised portion  79  mates up with a corresponding partial circular cutout  87  in a label sensor plate  82 , positioned on top of the label guide bracket  84 . The height of the slotted window  81  where the barcode  194  passes over the optical sensor  86  is critical for accurate barcode reading. To form a slot in just a metal plate with the specifications necessary to provide the accuracy required would be cost prohibitive. As illustrated in  FIG. 4C , the present invention provides a novel solution. A predetermined height H 3  is the critical space remaining when the label sensor plate  82  is positioned over the label guide bracket  84 . Height H 3  is the difference between predetermined height H 1  of the partial circular cutout  87  and predetermined height H 2  of the raised portion  79 . The partial circular raised portion  79  is also novel in that it is slightly angled upwards from a rounded edge opposite the flat edge, which terminates at the edge of the slotted window  81 . The raised portion  79  provides for a consistent elevation of the barcode  194  ( FIG. 14 ) as it passes over the optical sensor  86  and provides for a single point of contact, as opposed to the full length of a slot, while the carrier web  53  is fed under the label guide plate  80 . As shown in  FIG. 8B , the resulting combination of the slotted window  81 , the raised portion  79 , and the label sensor plate  82 , provide for accurate reading of the barcode  194  ( FIG. 14 ) and smooth flow of the carrier web  53  over the optical sensor  86 . 
   Cover Assembly—Platen Roller 
   Again referring to  FIGS. 4 ,  7 , and  8 , a label guide plate  80  is mounted to the label guide bracket  84  with screws  93  or other conventional means and is seen to includes severing means  78  for the label supply roll  55 , preferably shown as a serrated edge  78 , adapted to perforate the label supply roll  55  and facilitate tear-off of the exposed portion of the label supply roll  55 . The label guide plate  80  and the label guide bracket  84 , in conjunction with the platen roller  91 , define the path  89  of the label supply roll  55  ( FIGS. 7 and 8 ), moving across the print head  94 , and out through the cover assembly  28 , past the serrated edge  78  for removal. The platen roller  91  is held in place by apertures  75  formed within the label guide bracket  84  (see  FIG. 4 ). The platen roller gear  92  is disposed on an end of the platen roller  91  and is driven by the bi-directional stepper motor gear mechanism  121 . The label guide bracket  84 , and more specifically the label guide bracket yokes  83  coupled to the print head alignment pins  95 , aids in positioning the platen roller  91  directly over the print head  94  when the cover assembly  28  is in the latched closed position seen in  FIG. 10 . When the cover assembly  28  is in an open position ( FIG. 9 ), the platen roller  91  is retracted away from the print head  94  allowing for ease of installation of the label spindle  34  and ease of feeding the label supply roll  55  along the label supply roll path  89 . 
   Cover Latching Mechanism and Operation 
   As best seen in  FIG. 3 , a cover latch knob  139  is positioned on a first end of a cover latch arm  138 . As best seen in  FIG. 4 , a cover latch spindle  141  is secured to the cover latch arm  138 . Cover latches  146  are preferably mounted on the cover latch spindle  141  on the outside edges of the print head chassis  144 . A latch sleeve  148  may be positioned over the cover latch spindle  141  to aid in supporting the label supply roll  55  ( FIG. 7 ). As seen specifically in  FIG. 6 , a latch shaft roll pin  147  secures the latch spindle  141  to the print head chassis  144 . With reference to  FIG. 9 , a cover latch torsion spring  140  provides tension to urge the cover latch arm  138  to remain in a cover assembly open position. When the cover assembly  28  is in the open position shown in  FIG. 9 , an operator may position a reusable label spindle  34  within the print assembly  40  and feed the label supply roll  55  along the label supply roll path  89  shown in  FIGS. 7 and 8 . The operator may then close the pivotally attached cover assembly  28  over the label spindle  34  and urge the cover latch arm  138  in the direction indicated by arrow  137  on  FIG. 10 . The cover latches  146  engage the cover stop pins  143  to secure the cover assembly  28  in a closed position. Reversing this operation opens the cover assembly  28  to allow for removal of the label spindle  34 . As best seen in  FIGS. 9 and 10 , a limit switch  198  secured to the cover chassis  90  provides feedback to an operator to indicate when the cover assembly  28  is properly closed. 
   Spindle and Installation of Label Supply Roll 
   Referring now to  FIG. 14 , the label spindle is indicated generally by the reference numeral  34 . The label spindle  34  includes a label spool  50  and shaft  180 , preferably having a plurality of grooves  184  formed therein. Grooves  184  are adapted to receive o-rings  52 . The label spool shaft  180  receives the label supply roll  55 . The label spool cap  56  includes an aperture  182  formed therein. An end of the label spool shaft  180  containing a protuberance  57  is inserted into the label spool cap aperture  182 . The label spool cap  56  is then pushed toward the label spool until the label supply roll  55  is in close cooperation with both the label spool end  50  and the label spool cap end  56 . The o-rings  52  allow the label spool cap  56  to be positioned along the label spool shaft  180  to accommodate different width label supply rolls  55 . 
   Spindle and Spindle Installation into the Printing System 
   As best seen in  FIG. 1A , with the cover assembly  28  in an open position, the label spindle  34  is removably placed within the two spindle guide slots  49  and  51  ( FIGS. 3 and 6 ). Protuberance  47  on the label spool  50  is preferably configured such that it fits within spindle guide slot  49 , and protuberance  57  on an end of the label spool shaft  180  will only fit within spindle guide slot  51  (see  FIG. 14 ). This prevents improper placement of the reusable label spindle  34  within the printing system  20 . Spindle arm yokes  178  mate with the center pivot axle spacer  142 . The spindle arm yokes  178  and the label spindle protuberances  47  and  57  define a four-point label guide for the spindle  34 , thereby providing a consistent position of the label supply roll  55  presented to the print head  94 . 
   General Operation 
   The bi-directional stepper motor gear mechanism  121  of the printing system  20  is driven by circuitry to advance the label supply roll  55  and the thermal transfer ribbon  66 . When a desired character is input by a user or other means, the electronics of the printing system  20  energizes pixels on the print head  94  as the label supply roll  55  and the ribbon  66  advance past the print head  94 . The print head pixels are variously energized to imprint the character on the adhesive label  54 . After printing, the label supply roll  55  is advanced to a tear-off position, at which time the operator manually tears-off the exposed portion of the label supply roll  55  containing the printed label  54 . 
   With the structure of the printing system  20  and the novel cover assembly  28  and print assembly  40  described, a description of the operation of the printing system  20  will now be provided. 
   Installing the Ink Ribbon Cartridge 
     FIG. 10  depicts installation of the ink ribbon cartridge  30 . A user first opens the cover assembly  28  of the printing system  20  by pulling down on the cover latch arm  138  in a direction opposite that of arrow  137 . Referring to  FIG. 2 , the ribbon cartridge  30  is oriented so that the section of exposed ribbon  66  is directed toward the top  27  of the printing system  20 . The ribbon cartridge  30  is slidably inserted into the ink ribbon cartridge cavity  77  for a snap fit. The ribbon cartridge door  74  is engaged by pushing the latch  76  in the direction of arrow  207 . 
   Loading a Label Supply Roll on the Label Spindle 
   Now referring to  FIG. 1A , removal of label spindle  34  from the printing system  20  and installation of a new label supply roll  55  may be seen. The reusable label spindle  34  is readily removed from inside the printing system  20  when labels  54  are exhausted, or when different labels  54  are desired. 
     FIG. 14  further illustrates changing of the type of the label  54 . The user first pulls the label spool  50  and the label spool cap  56  apart. The label supply roll  55  having the desired label  54  type is received on the label spool shaft  180  with attention to the proper unwinding direction, indicated by the arrow  206  on each side of the label spindle  34 . The user then replaces the label spool cap  56  on the label spool shaft  180  until it just touches the label supply roll  55 . 
   Loading the Label Spindle in the Printing System 
   Again referring to  FIG. 1A , the loaded label spindle  34  is placed into the spindle compartment  31  of the printing system  20 . Again with reference to FIG.  14 , ends  47  and  57  of the label spindle  34  are of different sizes to thereby prevent improper loading. Two hooks or label spindle yokes  178  are provided on the label spindle  34  that are adapted to engage latch sleeve  148  (see  FIG. 6 ). 
     FIGS. 7 and 8  depict further loading of the label spindle  34 . The carrier web  53  is inserted into the bottom  212  of the label guide bracket  84  and is positioned so that the carrier web  53  exits through the top  214  of the guide bracket  84 . Once the carrier web  53  is moving smoothly under the label guide plate  80 , the printing system  20  cover assembly  28  may be closed, preferably without pinching the carrier web  53  or the label supply roll  55  inside the printing system  20 . When a new label supply roll  55  is loaded, the printing system  20  advances the supply roll  55  until it reads the barcode  194  on the back side  192  of the carrier web  53  ( FIG. 14 ), at which point the printing system  20  recognizes the size and spacing of the label  54 . 
   Navigating the Softkey Menu System 
   Now referring to  FIGS. 15 and 16 , a plurality of positions for “Softkeys”  210  located proximate the graphic display  26  may be seen. The function of the softkeys  210  changes depending on the MENU choice selected. The softkey function for each button  209  appears on the graphic display  26 , at a position proximate to each button  209 . This feature makes it easy for the user to navigate various menus without having to leave the image of a label  54  template. Pressing the MENU  220  key on the keyboard  24  returns the user to the default text edit options of LABEL, STATUS, SYSTEM, and PCLINK. From any point within the softkey  210  menu system, the DONE softkey  210  returns the user to the previous menu or screen while accepting any changes made in that current screen. 
   The Graphic Display 
   After loading a label supply roll  55  in the printing system  20  as described above, the graphic display  26  will depict an outline of the selected label  54 , scaled to the size of the graphic display  26  for maximum viewing and ease of editing ( FIGS. 15 and 16 ). This arrangement allows the user to view the placement and relative size of text, graphic images, or bar codes to be printed onto the label  54 . As previously mentioned, the graphic display  26  is capable of showing multiple font sizes, for example, small, medium, and large. This feature gives the user options to thereby create clean, crisp, readable labels  54 . The default text size will be the smallest displayable text font for the graphic display  26 . If the selected label  54  is too large for the display, the user sees the top and side outline of the label  54  and must scroll down to the bottom of the label  54  using the direction pad  242  or the ENTER  222  key on the keyboard  24 . 
   Applying Text to a Label 
   To apply text to a selected label  54 , as shown in  FIGS. 15 and 16 , a user may press the LABEL softkey  210  on the default menu. A user then presses the INSERT softkey  210  to add a line of TEXT, BARCODE, or an IMAGE as desired. A user types in the TEXT and then presses the ENTER  222  key on the keyboard  24  when complete. To add an additional line, the user may press the INSERT softkey  210  again and select either TEXT, BARCODE, or IMAGE. A second line will appear below the last line on the label  54  image. Again, the user can enter text and then press the ENTER key on the keyboard  24  ( FIG. 1 ) to complete the line. In a preferred embodiment, the default text size is usually the Medium or Normal text size. As the user types in the text, if the end of the line is reached, the text will automatically change to the Small text size allowing the user to continue. 
   Printing Labels 
   Still referring to  FIGS. 15 and 16 , after selecting the text to be printed on a label  54 , the user may print a single label  54 . To do so the user presses the PRINT  224  key on the keyboard  24 . If a user wishes to preview the label print layout and relative size, the user may press the PREVIEW  226  button on the keyboard  24 . The preview will be an estimation of the end print product and thereby allows the user to make modifications if desired without wasting any labels  54 . To print multiple labels  54 , press the FUNCTION  228  key and then the PRINT  224  key on the keyboard  24 . The user will be prompted for the PRINT QUANTITY. The user scrolls to the number needed by using the softkey buttons  209 . If a serial number has been created on the labels  54 , when FUNCTION  228  and PRINT  224  are pressed, the user will also be prompted for the QTY PER SERIAL. As an example, if two of each serial number are required (one for each end of a wire or cable) the user can set the QTY PER SERIAL as two and the printing system  20  will print two of each serial number before advancing to the next one. 
   Using the Fill Feature 
   If the user wishes to create one line of text on a label  54  and then repeat that text for as many lines as the label will allow, the user moves the cursor to the line created and presses the FILL softkey  210 . The printing system  20  will then copy this line to all other lines on the label. When the top line of a label is edited, all other lines will be automatically updated with it. 
   Adding a Serial Number to a Label 
   The printing system  20  of the present invention further allows printing of serial numbers on labels  54 . The user types a predetermined starting serial number (alpha, numeric, or both) on any open line of a selected label  54 . The cursor (not shown) is positioned on the line of text to be incremented, and the user presses the SERIAL  230  key on the keyboard  24 . This automatically flags the line as a serial number and the printing system  20  will start incrementing in a logical sequence, starting with the last digit in the line. As an example, if the line of text is 1000, then as the printing system  20  prints, that line will print as a serial number on each label: 1000, 1001, 1002, etc. If the user types in 10Y8 as the starting serial number (a four digit alphanumeric character), the printing system  20  will sequentially print the following: 10Y8, 10Y9, 10Z0, 10Z1, etc. An “S” will appear next to the EDIT  232  softkey  210  for any line that is set for serialization. To view the “S”, a user moves the cursor to the line that is selected for serialization. 
   If the user presses the PRINT  224  key on the keyboard  24 , when the label  54  has a serialized field on it, the printing system  20  will ask how many of each serial number the user wishes to print before printing the next serial number in the sequence. For instance, if the user requires two of each (one for each end of the wire or cable) the user depresses the  2   254  key on the keyboard  24  when prompted. 
   Vertical or Continuous Printing 
   The printing system  20  is further adapted to print on continuous (not separated by a gap) label material for terminal blocks, the front of patch panels, or any other application. In a preferred embodiment, the printing system  20  allows the user flexibility to change the print spacing by predetermined, for example 0.025″ (0.635 mm) increments from 0.30″ on up to 1″ or more between printed legends. 
   First, the software in the printing system  20  detects the width of the continuous stock (as there are no gaps to detect) and sets the proper heat code for the print head  94 . When the printing system  20  has read the barcode  194  successfully, the user is asked to setup the STYLE and SPACE. The user presses the STYLE softkey  210  to cycle through the following illustrative printing options: SQUARE, WIDE, and VERY WIDE. Selecting VERY WIDE will give the user a printable length that is 185% of the continuous label width. As an example, if a continuous label is 0.333″ (8.45 mm) wide, selecting VERY WIDE will produce a label that is 0.616″ long (0.333×1.85=0.616″). As a second example, if the label width was 1.0″ wide, then your label size would be 1.85″×1.0″ in dimension (1.0×1.85=1.85″). If the user selects WIDE, the label length is 150% of the width of the continuous label and if the user selects SQUARE, the label length is 100% of the width. By using the up and down arrow  244  keys on the keyboard  24 , the user may adjust the total distance between printed marks on the label  54 . The dimensions for inches or centimeters will change at the same time in 0.025″ (0.635 mm) increments. 
   Next, the user is asked to select the SPACE between printed labels. If the spacing between ports on a patch panel is 0.625″ (15.87 mm), then the user simply increments with the +/−25 softkeys  210 . The label  54  will be seen on the graphic display  26  in a horizontal format for easy editing, but will print vertically when printed. 
   Finally, the user may print the label  54  by pressing the FUNC  228  key and then the PRINT  224  key on the keyboard  24 . The user selects how many labels are required and presses the PRINT  224  key on the keyboard  24 . The printing system  20  will then print the information vertically as it exits the printing system  20 . To get the last printed label  54  in the strip, the user presses the FEED  236  button on the keyboard  24  until the last printed text is above the tear off point  78 . 
   Primary Keys 
   As best seen in  FIG. 1 , the keyboard  24  preferably comprises a complete arrangement of keys for the operation of the novel functionality of the printing system  20 . The keyboard  24  includes, but is not limited to the following primary keys: 
   FUNC  228  allows special characters or operators (shown in red on most keys) to be accessed. The user presses the FUNC  228  key first and then the key with the character or operation to use. 
   ESC  238  returns the user to the previous screen from any screen. By pressing the FUNC  228  and then ESC  238  keys, the current print job in progress will be aborted. 
   CLEAR  240  will delete an entire line of text. By pressing FUNC  228  and CLEAR  240 , an entire line of text will be deleted. 
   DIRECTION PAD  234  moves the cursor (not shown) through text without changing the text, and through options without selecting any options. The left and right arrow  234  keys move the cursor left and right one option/character at a time. The up and down  244  keys move the cursor up and down through lines of text, one line at a time or one option at a time. 
   SERIAL  230  automatically causes the last character in a line of text to start incrementing as each label is printed. 
   FEED  236  once advances one label at a time. Press and hold FEED  236  feeds continuously. 
   MENU  220  takes the user to the main menu of the printing system  20 . 
   POWER  246  turns the printing system  20  on. Pressing and holding the POWER  246  key for two seconds will turn the printing system  20  off. 
   ENTER  222 , while in an edit mode, moves to the next line on a label  54  when the user is entering text to a label. While in a function mode, ENTER  222  is used to select menu options, file names, and attribute changes. 
   PREVIEW  226  allows the user to view an entire label  54 , at a reduced scale, as it will print. As previously discussed, the PREVIEW  226  key is used to view the general layout and placement of text, graphic images, and barcodes prior to printing. 
   PRINT  224  prints the current label job. FUNC  228  and PRINT  224  allow the user to select how many of each label  54  and the total number of labels  54  to be printed. 
   CAPS  248  allows the user to toggle between upper and lower case letters. 
   DEL  250  removes one character to the left of the cursor. 
   UNDO  252  allows the user to undo the last change made to the label  54 . This also allows the user to retrieve lost lines or characters due to font size changes. 
   SPACE will insert a blank space in any line of text. 
   Moving a Line on a Label 
   Referring now to  FIGS. 15 and 16 , the user selects a line of text, barcode, or image on the graphic display  26  to be moved and presses the FUNC  228  key and then the “X”  256  key to CUT that line from the label  54 . The line may now be repositioned. The user presses the FUNC  228  key and then the “V”  258  key to paste the line above any currently selected line on the label  54 . Or, the user may press the FUNC  228  key and then the “A”  260  key to paste the line at the bottom of the label  54 . 
   Adjusting Print Quality 
   The printing system  20  is adapted to provide for the user the ability to adjust parameters that may affect print quality. In a preferred embodiment, the user can adjust the temperature of the print head  94  ( FIG. 4 ) and the speed at which the labels travel past the print head  94 . 
   To adjust the print quality, the user presses the MENU  220  key on the keyboard  24  followed by the SYSTEM softkey  210 . The user then presses the “&gt;” softkey  210  to scroll the softkey menu  210  to the right. The user presses the PARAM softkey  210 . Finally, pressing the BURN softkey  210  will adjust the heat used to transfer ink from the ribbon  66  ( FIG. 8 ) to the label  54 . Also, pressing the MOTOR softkey  210  will adjust the speed at which the label  54  travels past the print head  94  ( FIG. 7 ). 
   It is important to note that increasing burn temperature or slowing the speed of the label  54  down does not always solve print density. If the printing process is running too hot, the print will start to look washed out and the outer edges of each character will look darker than the inside of each character. In this case, using less temperature on the print head  94  will increase the print quality. 
   The length of the printed label can be defined using a “Set” feature. Continuous length labels or shrink tubing can be loaded vertically into the printing system  20 . The Set feature allows the length of label to be pre-set to almost any length. The printed text can be oriented vertical or horizontal when using this feature. This continuous vertical print option is extremely useful for patch panels, wall plates, terminal blocks, and wire markers. 
   The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention.