Abstract:
A print media sensor mounting assembly includes a housing having a sensor mounting element. The sensor mounting element has a sensor position movably mounted therein for movement of the sensor position amongst a plurality of positions corresponding to a width of a print media web.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This disclosure relates to a sensor assembly and, more particularly, to an adjustable sensor assembly for determining the location of at least one edge of print media.  
           [0003]    2. Description of the Related Art  
           [0004]    Printer sensors are typically used to determine the presence and location of the edge of the print media during operation. The printer requires a reference position in order to begin printing. This ensures that an appropriate location is available in the print area and that edge or over the edge printing does not occur. It is also desirable to be able to distinguish between labels, for example, on a continuous supply roll. The printer, therefore, can determine the appropriate start and finish locations on the print media in order to place a printed bar code, for example, on the appropriate label and advance the print media to the next location in a reliable and efficient manner.  
           [0005]    Sensors are used to determine the position of a label within a print head, that is, the distance that the print media has advanced. Traditional optical means of detecting the position of labels, for example, include a “through beam” system wherein an emitter is placed on one side of the label and a detector is placed on the reverse side. There are two methods of using “through beam” technology. These include gap and stripe indication. In the gap indication method, light is passed through the print media and gaps between labels are sensed as a change in light intensity.  
           [0006]    Stripe indication senses a black stripe printed on either side of the print media. When the indicator stripe is present, the light from the emitter does not pass through the labels and is not detected by the detectors. Stripe sensing can also be performed from one side of the media. A light source shines on the print media and the reflection is sensed to determine the position of the print media.  
           [0007]    In order for the position sensor to work properly the black stripe must be in line with the sensor. When various print media sizes are used, printers are typically provided with an additional sensor at each location for each size of the print media. This increases the complexity and cost for the printer, however, since numerous sensors are needed to accommodate print media of different sizes. Some printers typically require that the single sensor be removed and remounted each time a different size media is used.  
           [0008]    Printer versatility is desirable. Therefore, a need exists for a sensor, which can be easily adjusted to allow the use of various sized print media in the printer. A further need exits for such a sensor wherein the sensor is readily accessible and therefore does not require difficult disassembly steps in order to adjust the sensors position.  
           [0009]    Prior to the present disclosure, significant advances have been made in the prior art. An example of these improvements is the subject of U.S. Pat. No. 6,396,070 to Christensen et al., the contents of which are hereby incorporated by reference in their entirety.  
         SUMMARY OF THE INVENTION  
         [0010]    A print media sensor mounting assembly includes a housing having a sensor mounting element. The sensor mounting element has a sensor position movably mounted therein for movement of the sensor position to a plurality of predetermined positions corresponding to a width of a print media web.  
           [0011]    In particularly preferred embodiments, the printer sensor assembly includes a base defining a slot. A slide, for mounting a sensor therein, is slidably mounted within the slot and has at least one bump. A plurality of detents have predetermined locations formed within the base adjacent to the slot such that the slide is adjustably positioned and releasably secured in a predetermined location when at least one bump engages the detents.  
           [0012]    The sensor assembly may include a distal end portion of the slide having lateral extensions extending perpendicularly from a longitudinal axis and engaging a lower surface of the base. The lateral extensions may have at least one bump disposed thereon. The lateral extensions may be used to provide a force for holding bumps within a detent position, wherein the lateral extensions extend downward defining a bowed structure such that when the bowed structure is deflected a force is exerted. A cover plate may be used for attaching to the base such that the bowed structure is deflected to provide a preload force for holding bumps within a detent position. The sensor assembly can include a light sensor.  
           [0013]    In another embodiment, the printer sensor assembly includes a sensor base that defines a recess for receiving the sensor, the cable assembly, and the sensor slide. The sensor slide is slidably mounted to the sensor base and is adapted to receive a sensor. The sensor slide includes at least one arm having a button at its distal end for releasably engaging the detents of the sensor base. By releasing the button from the detent and applying motive force along the longitudinal axis of the sensor base, an operator can reposition the sensor slide to sense print media of a different size. The sensor operates in the same manner as in the previous embodiment.  
           [0014]    A further embodiment of the sensor assembly replaces the arm and detent structure of the previous embodiment with a threaded rod and wheel structure. The sensor slide is threadably engaged with the threaded rod and moves along the longitudinal axis of the sensor base as the threaded rod is rotated. The operator rotates the wheel that in turn rotates the threaded rod thereby transferring motive force to the sensor slide while the threaded rod is not movable in the longitudinal direction. In lieu of manual rotation of the threaded rod, an electric motor may be coupled to the threaded rod thereby allowing remote signals to control the motor and position the sensor slide in sensor assembly. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    The invention will be described in detail in the following description of embodiments with reference to the following figures wherein:  
         [0016]    [0016]FIG. 1 is an exploded view showing the components of an adjustable sensor assembly;  
         [0017]    [0017]FIG. 2 is an isometric view of a sensor base;  
         [0018]    [0018]FIG. 3 is an isometric view of a sensor slide;  
         [0019]    [0019]FIG. 4 is an isometric view of a lower surface of a first end portion of the sensor slide shown in FIG. 3;  
         [0020]    [0020]FIG. 5 is a bottom view of the sensor base;  
         [0021]    [0021]FIG. 6 is a sectional view of the sensor base sectioned along the line indicated in FIG. 5;  
         [0022]    [0022]FIG. 7 is an isometric view of an assembled adjustable sensor assembly;  
         [0023]    [0023]FIG. 8 is an end view of two sensor assemblies in placed in an operative position relative to one another;  
         [0024]    [0024]FIG. 9 is an exploded view of two sensor assemblies being installed within a print media feed;  
         [0025]    [0025]FIG. 10 is an isometric view of two sensor assemblies installed within a print media feed according to a first embodiment of the subject invention;  
         [0026]    [0026]FIG. 11 is a perspective view of two sensor assemblies installed within a print media feed showing a second embodiment of the subject invention;  
         [0027]    [0027]FIG. 12 is a perspective view of two sensor assemblies installed within a print media feed showing a third embodiment of the subject invention;  
         [0028]    [0028]FIG. 13 is an exploded view showing the components of a first embodiment of an adjustable sensor assembly illustrating a first embodiment of the subject invention;  
         [0029]    [0029]FIG. 13A is an exploded view showing the components of a second embodiment of an adjustable sensor assembly showing a second embodiment of the subject invention;  
         [0030]    [0030]FIG. 14 is an isometric view of two sensor assemblies installed within a print media feed according to a second embodiment of the subject invention; and  
         [0031]    [0031]FIG. 14A is a side cross-sectional view of first and second sensor assemblies according to a second embodiment of the subject invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0032]    The present disclosure describes an adjustable sensor assembly for printers. In order to sense the boundaries between labels, for example, or the position of an indicator stripe, sensors are installed inside a printer in an area where a print head is located. The adjustable sensor provides a sensor slide, which adjusts the location of a sensor mounted thereto. A sensor base provides a plurality of preset locations and locks the slide and sensor in place when the desired location is set. The plurality of preset locations corresponds to standard size print media.  
         [0033]    Referring now in specific detail to the drawings in which like reference numerals identify similar or identical elements throughout the several views, and initially to FIG. 1, one embodiment of an adjustable sensor assembly constructed in accordance with the present disclosure is shown generally as adjustable sensor assembly  10 . Adjustable sensor assembly  10  includes a sensor base  14 , a sensor slide  16 , a cover plate  12 , and a sensor  20 .  
         [0034]    Referring to FIG. 2, sensor base  14  has a front face  22 , first end portion  24 , and a second end portion  26 . Front face  22  of sensor base  14  has a slot  28  on first end portion  24  with a plurality of opposing detent pairs  30  formed at a lateral boundary  27  of the slot  28 . Slot  28  is formed longitudinally through sensor base  14 . Front face  22  forms a recess  32  on second end portion  26  along the longitudinal axis of sensor base. Recess  32  extends below front face  22  and remains parallel thereto. Recess  32  forms an open end  34  and a closed end  36 . Closed end  36  is located on second end portion  26 . Open end  34  leads into slot  28  and communicates therewith. A pair of slots  38  is located adjacent to both side of recess  32  and extend substantially the length of recess  32 . The preferred material for sensor base  14  is a moldable polymer.  
         [0035]    Referring to FIGS. 3 and 4, sensor slide  16  has a first end portion  50 , a second end portion  52 , an upper surface  54 , and a lower surface  56 . Second end portion  52  extends longitudinally from first end portion  50 . First end portion  50  has a center hole  60  therethrough and extended clips  62  extending from lower surface  56  for securing a sensor (not shown) adjacent to center hole  60 . Center hole  60  is provided to allow light signals to pass therethrough. Power and signals to the sensor are provided through a cable  18 . See FIG. 9. The sensor is mounted on lower surface  56  of first end portion between extended clips  62  during operation. Cable  18  is connected to the sensor and is routed longitudinally through the second end portion  52  and secured within sensor slide  16  by wire guides  80 . First end portion  50  has extensions  46  extending downward for slidably engaging slot  38  of sensor base  14 . Second end portion  52  has lateral sides  64 . Each lateral side  64  has a step  66  formed thereon. Second end portion  52  has a finger pad  68  disposed on upper surface  54  adjacent to an end  70  of sensor slide  16 . Two bumps  72  are formed on lateral sides  64  on a top surface  76  of steps  66 . End  70  also includes lateral extensions  74  disposed perpendicularly from the longitudinal axis and remaining below top surface  76  of steps  66 . The preferred material for sensor slide  16  is a moldable polymer.  
         [0036]    Referring again to FIG. 1, sensor slide  16  fits into recess  32  and slot  28  such that lateral extensions  74  and top surface  76  of steps  66  engage a lower surface  58  of sensor base  14 . See FIG. 5. Extensions  46  clip into slots  38 , which act as guides for sensor slide  16  and secure slide  16  to sensor base  14 . Sensor base  14  supports sensor slide  16  and allows longitudinal translation between detent pairs  30  of sensor base  14 . Opposing pairs of detents  30  are formed to receive two bumps  72  in order to set a location for sensor slide  16  and sensor  20 . When cover plate  12  is installed on sensor base  14 , lateral extensions  74  engage the surface of cover plate  12 . Lateral extensions  74  elastically deflect placing an upward force on second end portion  52  of sensor slide  16 . This force maintains bumps  72  in pair of detents  30  locking sensor slide  16  in a fixed location. If adjustment of sensor slide  16  is desired, finger pad  68  is depressed releasing two bumps  72  from pair of opposing detents  30 . Sensor slide  16  can now be repositioned and locked in place by releasing finger pad  68  at a new detent position.  
         [0037]    In a preferred embodiment, eight pairs of detents  30  are positioned along slot  28 . The detents  30  are spaced from a predetermined reference location to allow adjustment of sensor  20  for standard sized print media, for example, bar coded labels. It is contemplated that slot may have more detents  30  to allow more versatility of the printer. Detents  30  are marked to identify each location to provide the user with a set of reference labels  29 , for example, letters, to more easily determine the appropriate setting for the print media being used. It is further contemplated that sensor slide  16  can be locked in place at preset positions in a variety of ways. For example, sensor slide can have tabs laterally disposed for locking tabs into recesses within the slot.  
         [0038]    Referring now to FIGS. 5 and 6, cover plate  12  (FIG. 1) is installed onto lower surface  58  of sensor base  14 . Lower surface  58  of sensor base  14  is equipped with clips  82  and a pin  84  in order to secure cover plate  12  to sensor base  14 . Cover plate  12  defines an opening  86  on one end to allow cable  18  to pass. Sensor base  14  may be mounted to a surface adapted to receive clips  82  and pin  84  without the use of cover plate  12 . The surface functions as cover plate  12  providing engagement to lateral extensions  74  to maintain bumps  72  within pair of detents  30 .  
         [0039]    Referring to FIG. 7, an adjustable sensor assembly  10  is assembled showing sensor slide  16  mounted within slot  28  and recess of  32  of sensor base  14 . Cover plate  12  is shown mounted to sensor base  14 .  
         [0040]    Referring to FIG. 8, a working configuration is shown. A first sensor assembly  10   a  is installed above print media  90  and a second sensor assembly  10   b  is placed below print media  90 . Sensor base  14  has rounded edges  94  to aid in passing print media  90  therebetween. First sensor assembly  10   a  transmits a light impulse from sensor source (shown as part of sensor  16   a ) through print media  90  to second sensor assembly  10   b  where the signal is received by a detector (shown as part of sensor slide  16   b ). Sensors can be used to determine if print media is present, to read a position indicating stripe, to determine the location of the print media edge or to measure the presence of gaps for labels. When print media is changed, for example, a 4 inch wide label is replaced in printer by a 3.5 inch label. Sensor slides  16   a  and  16   b  are repositioned to corresponding detent positions to accommodate the new size of print media  90 .  
         [0041]    Power and signals to the sensor source and detector are provided through cable  18 . Cable  18  is connected to the sensor source or detector and secured within sensor slide  16  by wire guides  80 . See FIG. 3. Cable  18  passes around recess  32  to a second end  42  of sensor base  14 . Second end  42  defines an opening  44  to allow cable  18  to pass therethrough. Opening  86  in cover plate  12  corresponds to opening  44  and provides additional clearance for cable  18 . Slack must be stored within cable  18  to allow adjustment of sensor slide  16  within sensor base  14 . This is accomplished by routing cable  18  around recess  32 . Cable  18  is similarly routed in second sensor assembly  10   b.    
         [0042]    It is also contemplated that sensor assembly  10  can be used with a reflected light sensor, in which case, the sensor is both a source and a detector of light, requiring only one sensor assembly  10 . In this case, print media  90  passes over sensor assembly  10  reflecting light back to sensor assembly, which is read and processed.  
         [0043]    Referring now to FIG. 9, a first sensor assembly  10   a  is installed above a print media feed  92  and a second sensor assembly  10   b  is placed below print media feed  92 . Sensor assembly  10   a  and  10   b  each have a pair of threaded holes  96  at each end for securing to print media feed  92  by screws  98 . First sensor assembly  10   a  mounts to a top  100  of print media feed  92  and second sensor assembly  10   b  mounts to a bottom  102  of print media feed  92 .  
         [0044]    Referring to FIG. 10, top  100  rotates up to allow access to easily adjust sensor assemblies  10   a  and  10   b . During operation, top  100  is rotated down so that the sensor source of sensor assembly  10   a  can communicate with the sensor detector of sensor assembly  10   b  as shown in FIG. 8. In preferred embodiments, a light emitting diode or laser acts as a sensor source.  
         [0045]    [0045]FIGS. 11 and 13 illustrate an additional embodiment of the adjustable sensor assembly  210 . Referring to FIG. 11, the sensor assembly, or adjustable sensor assembly,  210  is shown installed in a print media feed. Under normal circumstances, a pair of sensor assemblies  210   a ,  21   b  will be installed in a print media feed as shown. Each sensor assembly  210   a ,  210   b  includes an elongated sensor base  214  having its longitudinal axis positioned perpendicular to the path of the print media. The sensor base  214  includes a front wall  222  and sidewalls  224 ,  226  that further define a recess  232 . The recess  232  is dimensioned to receive the sensor slide  216 . A pair of spaced apart channels  212  is disposed along the longitudinal axis of the sensor base  214  with each channel  212  extending from side wall  226  towards side wall  224  and forming part of the uppermost perimeter of recess  232 . A plurality of detents  230  is disposed along interior wall  228  below channel  212 .  
         [0046]    The sensor  220  and cable assembly  218  are slidably received by the recess  232  for motion along the longitudinal axis of the sensor base  214 . Preferably, cable assembly  218  includes flex cable  219  to avoid bunching up of the cable as the sensor  220  moves relative to the sensor base  214 . Directly above the sensor  220  is a sensor slide  216  that includes a centrally located grille  244 . The grille  244  is centrally located on the sensor slide  216  and has a plurality of slots that permit the transmission of light signals to and from the sensor  220 . The operation of the sensors  220  is the same as in the previous embodiment with the data being sent and received along cable  218 . In addition, the sensor slide  216  has a number of feet  242  that are slidably engaged in the channels  212  to maintain the relative orientation and position of the system components. A stud  234  and receptacle  236  are disposed on side walls  224 ,  226  for ensuring the correct physical alignment of the sensor assembly  210   a ,  210   b  when it is installed in a print media feed. Each sensor assembly  210   a ,  210   b  is constructed and installed such that the stud  234  of the first sensor assembly will positively align with the receptacle  236  of the second sensor assembly  210   b ,  210   a  thereby properly aligning the sensors  220  of the respective sensor assemblies  210   a ,  210   b . It is envisioned that other complementary structural combinations could accomplish this as well without departing from the scope of the invention. For example, a complementary arrangement of posts and holes or interleaving arms disposed along the top surface of each sidewall would achieve the same goal.  
         [0047]    As in the previous embodiments, the sensor  220  is movable along the longitudinal axis of the recess  232  with a predetermined discrete stop occurring at each detent&#39;s  230  position. Along one side of the sensor slide  216  is an arm  238  having a button  240  at its distal end. The arm  238  is flexible and, in its rest position, is sufficiently tensioned such that it moves towards interior wall  228  to ensure positive engagement with each detent  230 . To reposition the sensor slide  216 , the operator moves the arm  238  so that it deflects away from the interior wall  228  and the button  240  is disengaged from the detent  230 . Applying force along the longitudinal axis of the sensor base  214 , the operator slides the sensor slide  216  to the desired position and releases the arm  238 . The natural tension of the arm  238  causes the button  240  to move towards interior wall  228  and positively engage with the detent  230  for securely positioning the sensor slide  216 .  
         [0048]    Detection of the print media in this embodiment of the subject invention is identical to that of the first embodiment. Briefly, first and second sensor assemblies  210   a ,  210   b  are disposed in the print media feed as shown in FIG. 11. Thusly, the sensor  220  of the first sensor assembly  210   a  faces the sensor  220  of the second sensor assembly  210   b . Sensors can be used to determine if print media is present, to read a position indicating stripe, to determine the location of the print media edge, or to measure the presence of gaps for labels. When print media is changed, sensor slides  216  are repositioned to corresponding detents to accommodate the new size of print media.  
         [0049]    Power and signals to the sensor source and detector are provided through flex cable  219 . Cable assembly  218  is connected to the sensor source or detector and secured within sensor slide  216 . Slack must be stored within cable assembly  218  to allow adjustment of sensor slide  216  within sensor base  214 . This is accomplished by routing cable assembly  218  around recess  232 . Cable assembly  218  is similarly routed in second sensor assembly  210   b.    
         [0050]    Referring now to FIGS. 12 and 13A, a further embodiment of the sensor assembly is shown. In lieu of the predetermined positions of the detent style structure, this embodiment utilizes a threaded rod  318  that extends along the length of the sensor assembly  310  and protrudes through sidewall  324 . Furthermore, for this embodiment, the flexible arm attached to the sensor slide has been removed and so have the detents along the interior wall. Attached to the threaded rod  318  is a wheel  320  for adjusting the position of the sensor slide  316 . In this embodiment, the sensor slide  316  is threadably engaged to the threaded rod  318 . As the wheel  320  rotates, the threaded rod  318  rotates and transfers the rotational motion of the threaded rod  318  to the sensor slide  316  and moves it along the longitudinal axis of the sensor assembly  310 . This is advantageous because it allows the operator to precisely position the sensor in the recess  232  of the sensor base  314  instead of relying on predetermined detent locations. It is envisioned that the wheel  320  is normally disengaged from the threaded rod  318  and a positive action by the operator is required to engage the threaded rod  318 . This arrangement prevents inadvertent motion of the sensor slide  316 . For example, the wheel  320  may be spring loaded requiring the operator to push or pull the wheel  320  prior to rotating the threaded rod  318 . Alternately, the wheel  320  may be removable and only attached to the end of the threaded rod  318  when repositioning of the sensor slide is necessary. In this instance, the wheel  320  is attached to the end of the threaded rod  318  using a setscrew, cotter pin or other similar structures that positively engage the wheel  320  to the threaded rod  318 .  
         [0051]    In addition, a gear  330  is disposed in each sensor assembly  310   a ,  310   b  and is operatively coupled to each threaded rod  318 . As illustrated in FIGS. 12, 13A, and  14 A, each gear  330  is configured and adapted to extend vertically through a slot  348  in a top surface  346 . Preferably, each gear  330  is disposed substantially adjacent to sidewall  224  and substantially perpendicular to the threaded rod  318 . Configured thusly, when the sensor assemblies  310   a  and  310   b  are moved towards each other, studs  234  engage recesses  236  to align the sensor assemblies  310   a  and  310   b . Further still, gears  330   a ,  330   b  of the first and second sensor assemblies  310   a , and  310   b  releasably engage each other. During operation, rotation of threaded rod  318   a  in first sensor assembly  310   a  rotates gear  330   a . Since gears  330   a  and  330   b  are engaged, as shown in FIG. 14A, rotational motion of gear  330   a  imparts rotational motion to gear  330   b  thereby providing rotational motion to threaded rod  318   b . Due to the advantageous arrangement of gears  330   a ,  330   b  and threaded rods  318   a ,  318   b , sensor slides  316  are moved along the longitudinal axis of the sensor base  314  in unison, thereby maintaining their alignment to each other as they move relative to the sensor base  314 .  
         [0052]    Except for the alternate means of positioning the sensor slide, the remaining aspects of the sensor assembly operation are as in the previous embodiment. The upper and lower sensor assemblies  310   a ,  310   b  are preferably of the type utilizing the threaded rod  318  and wheel  320  arrangements. In addition, the structure employing the threaded rod  318  and wheel  320  assembly is easily adaptable for motorized operation by the optional incorporation of a small electric motor  350 , as illustrated in FIG. 14A. Further still, the addition of an electric motor  350  provides the foundation for remotely moving the sensors. By interfacing the electric motor  350  with the associated circuitry of the print media feed and/or the control wiring of the printer, remote signals can reposition the sensor assemblies  310   a ,  310   b  individually or in unison.  
         [0053]    Referring now to FIG. 14, a first sensor assembly  310   a  is installed above a print media feed  392  and a second sensor assembly  310   b  is placed below print media feed  392 . First sensor assembly  310   a  mounts to a top  300  of print media feed  392  and second sensor assembly  310   b  mounts to a bottom  302  of print media feed  392 . During operation, top  300  is moved generally downward so that the sensor source of sensor assembly  310   a  can communicate with the sensor detector of sensor assembly  310   b . In preferred embodiments, a light emitting diode or laser acts as a sensor source.  
         [0054]    Having described preferred embodiments of a novel sensor assembly (which are intended to be illustrative and not limiting), it is noted that modifications and variations can be made by persons skilled in the art in light of the above teachings. For example, it is contemplated that the sensor assembly can have remote adjustment capability. It is therefore to be understood that changes may be made in the particular embodiments of the invention disclosed which are within the scope and spirit of the invention.