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 to a plurality of predetermined positions corresponding to a width of a print media web.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This disclosure relates to a sensor assembly and, more particularly, to a adjustable sensor assembly for determining the location of at least one edge of print media. 
     2. Description of the Related Art 
     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. 
     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. 
     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. 
     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. 
     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. 
     SUMMARY OF THE INVENTION 
     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. 
     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 the at least one bump engages the detents. 
     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. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described in detail in the following description of embodiments with reference to the following figures wherein: 
     FIG. 1 is an exploded view showing the components of an adjustable sensor assembly; 
     FIG. 2 is an isometric view of a sensor base; 
     FIG. 3 is an isometric view of a sensor slide; 
     FIG. 4 is an isometric view of a lower surface of a first end portion of the sensor slide shown in FIG. 3; 
     FIG. 5 is a bottom view of the sensor base; 
     FIG. 6 is a sectional view of the sensor base sectioned along the line indicated in FIG. 5; 
     FIG. 7 is an isometric view of an assembled adjustable sensor assembly; 
     FIG. 8 is an end view of two sensor assemblies in placed in an operative position relative to one another; 
     FIG. 9 is an exploded view of two sensor assemblies being installed within a print media feed; and 
     FIG. 10 is an isometric view of two sensor assemblies installed within a print media feed. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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 correspond to standard size print media. 
     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 . 
     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 either side of recess  32  and extend substantially the length of recess  32 . The preferred material for sensor base  14  is a moldable polymer. 
     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. 
     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. 
     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. 
     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 . 
     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 . 
     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 . 
     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.    
     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. 
     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 . 
     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. 
     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 as delined by the appended claims. Having thus described the invention with the details and particularity required by the patent laws, what is claimed and desired protected by Letters Patent is set forth in the appended claims: