Abstract:
An image forming device for separating a printable medium from a continuous protective backing strip attached thereto includes a stepped stripper roller shaft encircled by a roller sleeve adapted to press a platen of the device wherein the image forming device causes the continuous strip to pass over a stripper bar and directs the protective backing strip to move under the stripper bar and between the platen and the roller sleeve while the printable medium continuously moves out of the device from over the stripper bar.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to image forming devices, and more particularly to a printer that automatically separates self-adhesive portions of print media from a continuous strip of protective backing without causing excessive looping or jamming of the printer. 
     BACKGROUND OF THE INVENTION 
     Self-adhesive labels have been in use for many years. Typically, self-adhesive labels come on a continuous strip, such as in a roll, and have a front side suitable for writing or printing information, an adhesive back side, and a protective backing forming the strip and adhering to the adhesive back side of the labels. Before using the printed labels, the labels must be peeled away from the protective backing and adhered to a medium, e.g., an envelope or a box, for labeling. 
     Conventional devices designed to print information on the self-adhesive labels and automatically peel off the printed (or imaged) labels from the protective backing include the Eltron LP-2042 printer. Typically, the continuous strip of the labels enters a conventional device, such as a printer from a first location of the device—normally the back side of the device. After entering, the strip passes through a contact area between a print head and a platen of the device, and then leaves the device from a second location-normally the front side of the device. Ideally, the printed (or imaged) labels should be peeled off from the protective backing strip as it leaves the device. Unfortunately, when certain printing processes (such as thermal transfer) and/or small media are used, conventional devices tend to fail when the protective backing forms a loop between the print head and an exit roller (which directs the protective backing out of the devices). Such failure may occur before and/or after the labels have been removed from the protection backing and may generally result in either the labels failing to detach and following the protective backing through the exit roller, or the labels only partially separating and adhering to the exit roller. 
     Other types of conventional devices do not automatically remove the protective backing from the labels and require the user to manually peel the protective backing off the printed labels. Such devices, however, are inconvenient for users and ifficient in today&#39;s busy world. Even so, these devices are also not immune from the above-noted looping problems. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an image forming device that will automatically separate detachable adhesive print media from a continuous protective backing strip without causing excessive looping or jamming to the image forming device. 
     One embodiment of the present invention provides an image forming device, e.g., a printer, comprising a print head; a platen for pressing a print medium, such as a sheet of paper or a series of self-adhesive labels attached to a continuous protective backing strip, against the print head and for moving the printing medium during operation; a stripper bar properly angled upward and adapted to separate the self-adhesive labels from the protective backing strip when it passes over the stripper bar; and a stripper roller positioned under the stripper bar. Initially the stripper roller causes the protective backing strip to pass under the stripper roller at a first speed sufficiently different from a second speed of the label strip passing between the print head and the platen to prevent looping or jamming of the protective backing and label strip. 
     In a preferred embodiment, the roller includes a stepped stripper roller shaft encircled by a sleeve and adapted to cause the protective backing strip to initially pass between the stripper roller and the platen at a first speed sufficiently different from a second speed of the strip passing between the print head and the platen until the tension on the protective backing strip reaches equilibrium which equalizes the first and second speeds of the protective backing strip respectively. The stepped roller shaft is also adapted to prevent looping of the protective backing strip when used in conjunction with narrow print media. 
     The foregoing and additional features and advantages of this present invention will become apparent by way of non-limitative examples shown in the accompanying drawings and detailed description that follow. In the figures and written description, numerals indicate the various features of the invention, like numerals referring to like features throughout both the drawing figures and the written description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows an isometric view of a lower part of a printer according to the present invention. 
     FIG. 2 shows a top plan view of the printer of FIG. 1 according to the present invention. 
     FIG. 3 shows an exploded view of the stripper roller of FIG. 1 according to the present invention. 
     FIG. 4 shows a side elevational view of the stripper roller, a lever, the platen and a cam of the device shown in FIG. 1, with the lever in operational position. 
     FIG. 5 shows a side elevational view of the stripper roller, the lever, the platen and the cam of the device shown in FIG. 1, with the lever in loading position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a preferred embodiment of the present invention where a continuous label strip  14  is fed into a drive part  1  of a printer from a back side of the printer. The continuous label strip  14  comprises sequentially arranged self-adhesive labels  10  attached to a continuous protective backing strip  12 . Each of the self-adhesive labels has a printable side and a self-adhesive side adhered to the protective backing  12 . Moreover, the continuous label strip  14  is typically wound to form a label roll before being supplied into the printer. After entering the printer, the label strip  14  goes through and between two pathway guides  16 ,  18  for guiding the label strip  14  toward a front side of the printer. The pathway guides  16 ,  18  are movably coupled to a shaft  30 , as shown in FIG. 2, and are equally spaced apart at opposite sides from a midpoint of the shaft  30 . The midpoint of the shaft  30  is approximately located at the middle of the shaft  30  having an equal distance from opposite side walls  56 ,  58  of t he drive part  1 . As a result, the pathway guides  16 ,  18  guide the label strip  14  to pass through the printer where the labels passing within the printer are centered therein to provide an optimum printing result. 
     The shaft  30  is rotatably coupled to the drive part  1  at the bottom by threading through opposite side walls  56 ,  58  of the drive part  1 . The shaft  30  has right and left halves respectively coupled to pathway guides  16 ,  18 , and has a middle part integrally coupled to the left and right halves at opposite ends. The middle part of the shaft  30  is also supported by a middle support rack of the drive part  1  for further supporting the shaft  30 . The shaft  30  has worm notches across the left and right halves, but there are no notches on the middle part of the shaft  30 . The worm notches have opposite rotational directions respectively on left and right halves of the shaft  30 . A rotating nob  20  is securely coupled to the shaft  30  at the one end (left) for rotating the shaft  30 . The pathway guides  16 ,  18  respectively have ring parts at their bottoms. The ring parts of the pathway guides  16 ,  18  encircle the respective right and left halves of the shaft  30  and have inner worm grooves meshing with the worm notches of the shaft  30 . The meshing of the grooves and notches allows the pathway guides  16 ,  18  to move along the shaft  30  by rotating the shaft  30 . However, due to the opposite rotational notch settings of the left and the right halves, the left and right halves of the shaft  30  will respectively cause the pathway guides  16 ,  18  to move in opposite directions along the shaft  30  when the shaft  30  rotates. Thus, when the shaft  30  rotates in a first direction, the pathway guides  16 ,  18  will be moved toward each other, and they will be moved away from each other when the shaft  30  rotates in a second direction, opposite to the first rotational direction. A user of the printer may therefore rotate the rotating nob  20  to adjust the relative distance between the pathway guides  16 ,  18  for accommodating different printing media having different dimensions. 
     The printer has a platen  22  disposed in the drive part  1 , and has a print head (not shown) located in a print part, which is pivotally coupled to the drive part  1  at the back side. Thus, the print part may be pivotally opened from the drive part  1  for a loading position of a printing medium, such as the label strip  14 , and may be closely engaged to the drive part  1  for an operation position. The print head is positioned over the platen  22  when the drive part  1  is closely engaged to the print part of the printer during operation. Therefore, in normal operation, the platen  22  will press the printing media, such as the label strip  14 , tightly against the print head to allow forming data images on the printable side of the labels. The platen  22  has a platen shaft  23  rotatably coupled to the drive part  1  at opposite side plates  56 ,  58 . Thus, when the platen  22  rotates during operation, it will drag the label strip  14  through the printer, thereby the labels of the label strip  14  could be sequentially printed by the print head. 
     To load the label strip  14 , the label strip  14  is first inserted through an opening near the back side of the drive part  1 . The label strip  14  then passes between the pathway guides  16 ,  18  horizontally and between the print head and the platen  22  vertically wherein the platen  22  is positioned beneath the label strip  14  and the print head is positioned over the label strip  14 . The lower side of the label strip  14 , that touches the platen  22 , comprises the protective backing  12  while the upper side includes the printable surface of the labels  10 . As stated, the label strip  14  is tightly trapped in the printer between the print head and the platen  22  when the printer is in the operation position. As a result, when the platen  22  rotates, it will force the label strip  14  to move through the printer in a direction tangential and centrifugal to a rotational direction of the platen  22 . In the normal operation, the platen  22  rotates counterclockwise, viewed in from the right side plate  56  of the drive part  1 , so that the label strip  14  is pulled by the platen  22  toward the front side of the printer. In addition, the platen  22  is connected by a gear system, having a series of gears including a gear  24  as indicated in FIG. 1, to a motor  26  positioned at the right end of the drive part  1 . The motor  26  drives the gear system to rotates the platen  22  such that the platen  22  will urge the label strip  14  to move through the printer (see also FIG.  2 ). 
     Normally, the printer has a locking mechanism, which will be explained in the followings, to open up a gap between the print head and the platen  22  for inserting the label strip  14 , or to closely engage them for the operation. During the printing operation, the print head is locked into place to contact the upper printable side of the labels  10 . With the print head lowered into place and contacting the labels  10 , a small amount of friction is created as the label strip  14  passes through and beneath the print head during printing. This small amount of friction is important to the operation of the present invention, as will be explained more detailedly in the paragraphs that follow. 
     Just after passing between the print head and the platen  22 , the label strip  14  passes over a stripper bar  28  located at the front side of the printer  1 , as shown in FIGS. 1 and 2. The stripper bar  28  is basically a flat panel plate, preferably made by stainless steel or other metal materials, having a wide center portion and two narrow portions, with same length, respectively positioned at opposite ends (left and right) of the stripper bar  28 . In one example, the overall length of the stripper bar  28  is approximately 5.63 inches long, roughly the same length between the left and right side plates  56 ,  58  of the drive part  1 . Thus, the stripper bar  28  may be coupled to the drive part  1  by inserting the narrow portions of the stripper bar  28  into respective receiving slots on the opposite side plates  56 ,  58 . The center portion of the stripper bar  28  is approximately 4.75 inches long and is slightly longer than the platen  22 , whose length is of approximately 4.4 inches. The stripper bar  28  is angled upward from a level position with its lower bottom end positioned close to, but not touching platen  22 . The lower bottom end of the slanted stripper bar  28  is also positioned slightly above a surface intersection line, which is the tangential intersection line of the platen  22  and a vertical plane, of the platen  22 . As will be explained in further details later, the angle of the stripper bar  28  is suitably positioned in order to separate a portion of the protective backing  12  from a label  10  directly over the stripper bar  28 . In a preferred embodiment, the angle of the stripper bar  28  is approximately 30° to 50°, preferably 40°, measured from a level position upward. The angle of stripper bar  28 , however, may be of any degree as long as it is suitable to separate the labels  10  from the protective backing  12  when the label strip  14  passes over the stripper bar  28 . 
     After passing over the stripper bar  28 , the labels  10  will be allowed to flow straight out of the printer at the front side, while the protective backing  12  will be threaded back underneath the stripper bar  28  and over, behind and then underneath a stripper roller  32 . As shown in FIG. 3, the stripper roller  32  includes a shaft  38  movably coupled to the drive part  1  at opposite ends and a sleeve  42  rotatably encircling the stripper shaft  38 . A pair of roller receiving holes (not shown) are respectively positioned at opposite side plates  56 ,  58  of the drive part  1  to receive the opposite ends of shaft  38 . The roller receiving holes are of approximately elliptic shape in a slanted down position toward the front side, and are slightly larger than a diameter of shaft  38  to allow the stripper shaft  38  to reciprocally slide therein. The stripper roller  32  is located in front of and lower than the platen  22 , thereby the position of the stripper roller shaft  38  is approximately 45° to 60° angled down from a horizontal plane passing through a center axle of the platen shaft  23 . In normal operation, stripper roller  32  is pressed tightly against platen  22 , while in the loading position, stripper roller  32  is urged away from the platen  22  for threading the protective backing  12  between the platen  22  and the stripper roller  32 , as will be explained further. 
     A pair of left and right cam levers  37 ,  36  is rotatably coupled to the stripper shaft  38  near the opposite ends inside the respective side plates  56 ,  58 , as shown in FIG.  2 . The left and right cam levers  36 ,  37  respectively have extending portions having cam-shape contour and positioned directly underneath the platen shaft  23 . In addition, a pair of levers  34 ,  35  is securely coupled to the stripper shaft  38  at the opposite ends (left and right) outside of the respective side plates  58 ,  56  of the drive part  1 . Correspondingly, a pair of torsional springs  48 ,  52  urges the respective levers  34 ,  35 , and thus the stripper roller  32 , toward the back end of the drive part  1 . Thus, the torsional springs  48 ,  52  urge the stripper roller  32  tightly against the platen  22  during operation. The lever  34  has an upwardly extending handle, as shown in FIG. 1, and a ring shape bottom securely encircling the stripper shaft  38 , as shown in FIGS. 4 and 5. As a result, a user may pull the handle of the lever  34  to rotate the stripper shaft  38 , which, in turn, rotates the cam levers  36 ,  37 , thereby the stripper roller  32  may be forced to move toward or away from the platen  22  by the cam levers  36 ,  37 , as will be explained in further details. In a preferred embodiment, the sleeve  42  is made of fluorinated ethylene propylene TEFLON, hereinafter referred to as FEP TEFLON due to the properties of the FEP TEFLON that are suitable to the operation of the present invention, as will be explained further detailed in the following paragraphs. However, it is possible that other materials may be used for the sleeve  42  as long as they produce similar results as the FEP TEFLON does for the present invention. Moreover, the platen  22  may be made of any suitable materials that are commonly adopted to make platens by persons skilled in the art. 
     The FEP TEFLON provides a number of advantages suitable for the sleeve  42  of the present invention. First, a bearing surface, which is on the outer surface of the sleeve that carries the protective backing  12 , of the FEP TEFLON sleeve is smooth and offers little friction for the protective backing  12  to pass through. Second, the bearing surface of the FEP TEFLON sleeve is a none-sticking bearing surface. Therefore, in some rare cases, if a label is only partially peeled off after passing the stripper bar  28  and follows the protective backing  12  to the stripper roller  32 , the label may stick to the sleeve  42  when it approaches the stripper roller  32 . By having a non-sticking surface of the sleeve  42 , peeling the stuck label off the FEP TEFLON sleeve  42  in this rare case of failure would be easier. Finally, a lubricant may be added between the sleeve  42  and the stripper shaft  38  to reduce a rotational friction between the sleeve  42  and the stripper shaft  38 . It has been found that the FEP TEFLON is suitable to work with most lubricants. All these properties of the FEP TEFLON make it particularly suitable to be the material for the sleeve  42 . 
     As can be seen in FIGS. 4 and 5 in conjunction with FIG. 1, in order to thread backing strip  12  around the stripper roller  32 , the user will have to engage the lever  34 , which is coupled to the adjacent left end of the stripper shaft  38  and to the cam lever  36 . When rotated to a loading position by pulling the lever  34  toward the front end of the printer, as shown in FIG. 5, the lever  34  rotates the cam lever  36 , and also the cam lever  37  at the other end of shaft  38 . As can be seen in FIG. 6, the cam levers  36 ,  37  together urge the stripper roller  32  away from platen  22  creating enough room for the protective backing strip  12  to be threaded between the platen  22  and the stripper roller  32 . FIG. 4 shows lever  34  and cam lever  36  in an operational position. As stated, the printer also comprises a pair of torsional springs  48 ,  52  for urging the stripper roller  32  against the platen  22  thereby maintaining a tight pressure between the stripper roller  32  and the platen  22  during operation. The torsional springs  48 ,  52  are respectively positioned outside of the side plates  58 ,  56  and before the levers  34 ,  35 . The torsional springs  48 ,  52  respectively have extruding spring plates contacting the levers  34 ,  35  to urge the stripper roller  32  against the platen  22 . 
     In an alternative embodiment, the levers  34 ,  35  and/or the cam levers  36 ,  37  may also be configured to release the print part from engaging to the drive part  1  of the printer so that the print head may be disengaged from contacting the platen  22  in order to allow the threading of the label strip  14  between the print head and the platen  22 . In the above-mentioned alternative embodiment, the levers  34 ,  35  may respectively have cam-shape latches adjacent to the side plates  58 ,  56  and slightly higher than the top surface of the side plates  58 ,  56 . Correspondingly, the print part of the printer has a pair of latching cams properly positioned relative to the cam-shape latches of the drive part  1  so that the cam-shape latches will latch with the latching cams of the print part when the two parts are pivotally closed to each other. The torsional springs  48 ,  52  also serve to urge the levers  34 ,  35  to lock with the print part during operation. As a result, the user may release the print part from engaging to the drive part  1 , and also to simultaneously release the platen  22  from pressing against the stripper roller  32 , by pulling the lever  34  toward the front side of the printer. 
     The labels  10  have printable front sides and adhesive back sides adhered to the protective backing  12 . However, the protective backing typically has a gloss surface and most adhesive glue applied on the back side of the labels  10  are often not very sticky in order not to impede peeling off the labels from the protective backing  12 . As a result, when the label strip  14  is bent over a certain angle, e.g., 45°, a label just over the bending line of the label strip  14  normally would separate apart from the protective backing  12  and moves in a tangential direction at the bending line relative to the protective backing  12 . As noted, the label strip  14  is inserted into the printer through the opening at the back side of the drive part  1 . Once entering the drive part  1 , the label strip  14  passes through the pathway guides  16 ,  18  horizontally and between the print head and the platen  22  vertically for receiving printing images on the labels  10  from the print head. After passing through the platen  22 , the label strip  14  proceeds over the upwardly angled stripper bar  28  for separating the labels  10  from the protective backing  12 . Thereafter, the protective backing  12  is directed backward underneath the stripper bar  28  and over, behind and underneath the stripper roller  32  to come out of the drive part  1  from the bottom of the stripper bar  28 , as shown in FIG.  1 . Since the protective backing  12  is threaded back under the stripper bar  28 , the labels  10  will ordinarily move tangentially toward the front side of the printer after passing the stripper bar  28  and will not follow the protective backing  12  to the underside of the stripper bar  28 . Thus, the labels  10  will be automatically peeled off the protective backing  12  when they pass the stripper bar  28 . 
     As noted, the protective backing  12  usually has a gloss and smooth surface on one side, which is attached to the adhesive side of the labels  10 , to allow the labels  10  to be peeled off easily. Because the protective backing  12  is designed to allow the labels  10  to be peeled off very easily, the labels  10  can be separated from the protective backing  12  by folding the strip  14  at an edge of a label  10  over a certain critical angle. The critical angle of a specific self-adhesive label may be the same as or slightly different from others. In a preferred embodiment, the present invention comprises a stripper bar  28  having an acute upward angle of approximately 27° to 32° to ensure all labels  10  will be separated from the protective backing  12  when the strip  14  passes the stripper bar  28  while the protective backing is threaded back and underneath the stripper bar  28 , as shown in FIG.  1 . 
     After protective backing  12  is directed backward under the stripper bar  28 , the protective backing  12  is threaded between the platen  22  and the stripper roller  32  to direct it out of the printer in a forward direction. The user will then pivotally fold down the print part to engage the drive part  1 , and will move the lever  34  back into its operational position (as shown in FIG.  4 ), that rotates the cam levers  36 ,  37  and therefore moves the stripper roller  32 , the platen  22 , and the print head back to its operational position. Thus, the protective backing  12  is trapped between the stripper roller  32  and the platen  22 , and the label strip  14  is trapped between the print head and the platen  22 . As stated previously, the protective backing  12  may therefore be separated from the labels  10 , which move directly out of the printer from over the stripper bar  28 , and comes out of the printer through moving underneath the stripper roller  32 . 
     As shown in FIG. 3, the stripper roller  32  comprises a stepped shaft  38  surrounded by the sleeve  42 . In the preferred embodiment, the stepped shaft  38  is made of any 300 series stainless steel, and the sleeve  42  is made of FEP TEFLON, but other suitable materials may be adopted for shaft  38  or sleeve  42 . In one example, the FEP TEFLON sleeve  42  has an exterior diameter of approximately 0.419 inches, an interior diameter of approximately 0.25 inches, and is approximately 4.72 inches in length. The stripper roller  38  is approximately 5.98 inches long. The stripper roller shaft  38  has a first diameter, measured on the portion of the shaft  38  from either end of the stripper roller shaft  38  to a set of first steps  44 , of approximately 0.156 inches; a second diameter, measured on the portions of the shaft  38  from either first step  44  to an adjacent second step  46 , of approximately 0.204 inches; and a third diameter, measured on the portion of the stripper roller shaft  38  between the two second steps  46 , of approximately 0.236 inches. The stripper roller shaft  38  is generally symmetrical, with the distance (in the same example) between either end and the adjacent first step  44  of approximately 0.62 inches, the distance between either first step  44  and the adjacent second step  46  of approximately 1.87 inches, and the distance between the two second steps  46  of approximately 1.0 inches. As can be seen, even at the point of the greatest diameter, i.e., the third diameter, of the stripper roller shaft  38  there is a radial clearance between the stripper roller shaft  38  and the FEP TEFLON sleeve  42  of about 0.014 inches. This clearance (in addition to other inherent properties of FEP TEFLON) permits the FEP TEFLON sleeve  42  to rotate freely about the stripper roller shaft  38 . As a result, the stripper roller shaft  38  does not generally rotate during normal operation. 
     When the printer is operational, the motor  26  turns the gears of the gear system  24 , which, in turn, rotate platen  22  to urge the label strip  14  to move forward by passing between the print head and platen  22 . During printing, the print head prints data on labels  10  and creates a small amount of friction on label strip  14  when it slides over the print head. The small amount of friction has a slight slowing effect on the speed of label strip  14 . Moreover, the pressure from platen  22  against the protective backing strip  12  and the stripper roller  32  drives the stripper roller  32  to rotate and thus forces the protective backing strip  12  to pass underneath the stripper roller  32 . 
     Due partially to the gloss surface of the protective backing  12 , it has been found that when the protective backing  12  passes between the platen  22  and the stripper roller  32 , it encounters less resistance than the label strip  14  passing between the print head and the platen  22 . Therefore, when the printer starts to print, the stripper roller  32  and the platen  22  together will initially pull the protective backing  12  faster than the print head and the platen  22  pulling the label strip  14 . As a result, a small tension will be gradually accumulated in a section of the protective backing  12  between the stripper roller  32  and the print head. An equilibrium level of the tension is reached when the stripper roller  32  can no longer overcome the friction created by the print head and move the protective backing  12  at a faster rate than that traveled at by the label strip  14 . Therefore, the tension will be kept accumulating until such time that the tension in the protective backing  12  becomes strong enough to counter act the speed differential. At this point, the tension reaches the equilibrium level and the protective backing  12  and the label strip  14  will be moved in a same speed. Once the equilibrium level of the tension is reached, the printer tends to move the protective backing  12  and the label strip  14  at the same speed while maintaining the equilibrium tension level on the protective backing  12  to keep it straight. 
     Moreover, whenever there is a slack of the protective backing  12  initially, the speed differential will again cause the tension to increase toward the equilibrium level. As a result, the tension built up thereon will help straighten the portion of the protective backing  12  between the stripper roller  32  and the stripper bar  28 . This tension on the protective backing  12  will not only straighten the protective backing  12  but also help the printer avoid undesirable looping of the protective backing  12 , or other forms of failure of the label strip  14  associated with the slack paper problem. 
     As labels  10  are printing, the acute angle of the fold of the label strip  14 , as it passes over the stripper bar  28  while the protective backing  12  is threaded back and then under the stripper bar  28 , continues to separate the protective backing  12  from the labels  10 . In addition, the above-noted tension will also help maintaining the proper angle of the fold as the label strip  14  passes over the stripper bar  28 . Should the tension become too great, the FEP TEFLON sleeve  42  will “slip” against the protective backing  12  and thus maintains the equilibrium level of tension on the protective backing  12  and the label strip  14  for proper printing. The “slip” of the FEP TEFLON sleeve  42  is partly due to the lubricants filled in the radial clearance between the FEP TEFLON sleeve  42  and the stripper shaft  38 . 
     Most conventional printing devices do not experience the above-mentioned initial speed differential and are subject to failures, particularly the looping of the label strip  14  and/or of the protective backing  12 . The conventional devices also have no mechanisms to maintain tension on, and, thus, to straighten, the backing  12 . This problem is especially acute with thermal transfer printers, which cause less drags of printing strips than direct thermal printers and do not have the same magnitude of frictions to cause a speed differential that increases the tension of the protective backing  12 . A similar problem also exists when a narrow media (e.g., less than one inch wide) is used. Such a narrow printing surface has been found particularly susceptible to looping and failure unless a sufficient tension is maintained between the strip  14  and the protective backing  12 . The looping problem of the conventional printing devices when used in conjunction with the narrow media is primarily due to the fact that the conventional printing devices, when designed and built, normally do not take into consideration to accommodate the narrow media. 
     In contrast, the present invention does not have the above-mentioned problems encountered by thermal transfer printers and/or for using narrow print media. To begin with, it has been found that implementing the present invention causes sufficient tension on protective backing strip  12  to prevent the looping problem in thermal transfer printers and/or of the narrow printing media. Moreover, stepped stripper roller shaft  38  of the present invention is particularly suitable for accommodating narrow print media. As previously mentioned and shown in FIG. 3, the center portion of stripper roller shaft  38 , which is between the set of second steps  46 , has the largest diameter on the stepped shaft  38  which in one example is of approximately 0.236 inches and of approximately 1.0 inches in length, respectively. Only the center portion of the stripper roller shaft  38  touches and presses against the encircling FEP TEFLON sleeve  42  during operation when the FEP TEFLON sleeve  42  rotates about the stripper roller shaft  38 . Thus, the stepped shaft  38  helps stripper roller  32  press against the protective backing strip  12  by focusing most of the pressure on the center portion of the protective backing strip  12 . When a narrow printing strip is used, even as narrow as one inch long, the present invention will still provide adequate pressing force more evenly distributed on the narrow strip to move a protective backing of the narrow strip through the printer. 
     From the foregoing, it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made by persons skilled in the art without deviating from the spirit and/or scope of the invention. For example, the dimensions of the stripper roller, and its relevant parts such as the stripper shaft, may be changed to accommodate different printing devices. The relative proportion of different parts of the stripper roller shaft may also be changed to accommodate any specific purpose. The sleeve may be made of materials, other than the FEP TEFLON, suitable to create speed differential and to “slip.” Furthermore, the angle of the stripper bar may be changed to ensure the labels will be separated from the protective backing when the strip passes over the stripper bar while the protective backing is threaded back and underneath the stripper bar. Accordingly, the present invention is not limited except as by the appended claims and their equivalents.