Abstract:
A item checkout device and weigh plate with improved electromagnetic field performance. The item checkout device includes a housing, an electromagnetic field generator in the housing, a barcode reader in the housing, a scale assembly in the housing, and the weigh plate. The weigh plate is supported by the scale assembly and includes a non-metallic planar section located over the electromagnetic field generator and having a top surface resistant to damage and substantially transparent to an electromagnetic field from the electromagnetic field generator, and a window coplanar with the non-metallic planar section and located over the barcode reader.

Description:
BACKGROUND 
       [0001]    Item checkout devices suited for checkout counter operation typically include a barcode reader and a scale assembly. A weigh plate rests upon the scale assembly. Such item checkout devices may also be outfitted with an electronic article surveillance (EAS) mounted beneath the weigh plate for detecting and deactivating security tags on products and/or a radio frequency identification (RFID) system for reading RFID tags on products. 
         [0002]    There is a mindset in the barcode scanner industry to use metal for surfaces that take the most abuse. Therefore, weigh plates are made of metal, such as aluminum, steel, or stainless steel. Some may include a metal top skin on a substrate. The use of metal provides rigidity, and enhances cleanliness at the checkout environment. However, the use of metal, particularly stainless steel, is expensive. 
         [0003]    Metal also acts as a shield between an EAS system and security tags on scanned products, and between an RFID system and RFID tags on scanned products. 
         [0004]    To overcome shielding, EAS system providers must increase deactivation field strengths to levels that raise concerns over operator safety. 
         [0005]    It would be desirable to provide an improved weigh plate that addresses these concerns. 
       SUMMARY 
       [0006]    An item checkout device and weigh plate with improved electromagnetic field performance is provided. 
         [0007]    The item checkout device includes a housing, an electromagnetic field generator in the housing, a barcode reader in the housing, a scale assembly in the housing, and the weigh plate. The weigh plate is supported by the scale assembly and includes a non-metallic planar section located over the electromagnetic field generator and having a top surface resistant to damage and substantially transparent to an electromagnetic field from the electromagnetic field generator, and a window coplanar with the non-metallic planar section and located over the barcode reader. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a block diagram of an example item checkout device. 
           [0009]      FIG. 2  is an example embodiment of a weigh plate. 
           [0010]      FIG. 3  is a block diagram of an example barcode reader. 
           [0011]      FIG. 4  is a perspective view of an example checkout device. 
           [0012]      FIG. 5  is an exploded view of the example checkout device of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    With reference to  FIG. 1 , item checkout device  10  includes barcode reader  12 , scale assembly  14 , electronic article surveillance (EAS) system  16 , and radio frequency identification (RFID) system  18 . 
         [0014]    Barcode reader  12  may include any type of technology for reading barcode  32  on item  30 , including but not limited to laser-based barcode reading technologies, image-based barcode reading technologies, and combinations of both laser and image-based barcode reading technologies. 
         [0015]    Scale assembly measures and records weights of produce items. Scale assembly  14  includes one or more load cells  20  and weigh plate  22 . Load cell  20  may be mounted at a low point in item checkout device  10  and a conventional weigh plate support bar (e.g., an “H” bar) may be mounted on load cell  20 . Alternatively, load cell  20  may include a planar beam load cell, such as the planar beam load cells manufactured by Flintec, Inc. A plurality of planar beam load cells may be mounted above barcode reader  12 . 
         [0016]    EAS system  16  detects and deactivates security tags  34  on items  30 . EAS system  16  may be located below weigh plate  22 . EAS system  16  may be manufactured by companies such as Sensormatic, Inc., or Checkpoint, Inc. As such, security tags  34  may be of magnetic or fuse types. 
         [0017]    EAS system  16  may include one or more coils  24  mounted below weigh plate  22 . Coil  24  wirelessly senses the presence of security tag  34  and deactivates security tag  34 . Depending upon type of security tag  34 , coil  24  either produces a demagnetizing field or induces a fuse destroying current. 
         [0018]    RFID system  18  includes reader  26  for wirelessly reading RFID tag  36  on item  30 . RFID system  18  may be located below weigh plate  22 . 
         [0019]    Item checkout device  10  additionally includes control circuitry  28  which controls operation of item checkout device  10 , including operation of barcode reader  12 , scale assembly  14 , EAS system  16 , and RFID system  18 . Control circuitry  28  may include a single control circuitry or several control circuits associated with barcode reader  12 , scale assembly  14 , EAS system  16 , and RFID system  18 . 
         [0020]    Control circuitry  28  decodes information encoded in barcode label  32 , and sends the information in barcode label  32  and the information in RFID tag  36  to point-of-sale (POS) terminal  38 . 
         [0021]    Variations of checkout device  10  are envisioned. For example, electromagnetic field generators may or may not be installed within item checkout device. For example, RFID system  18  may be present, but not EAS system  16 , or vice versa. Correspondingly, item  30  may not always include security tag  34  or RFID tag  36  or both. Weigh plate may be installed 
         [0022]    With reference to  FIG. 2 , an example weigh plate  22  includes four generally planar sections  40 - 46  and window  50 . In alternative embodiments, weigh plate  22  may include other numbers and combinations of sections. For example, weigh plate  22  may be configured in one section as all non-metallic. As another example, weight plate  22  may be predominantly non-metallic but include one or two additional metal sections for rigidity and support. Weigh plate  22  may have more than four sections as well. 
         [0023]    Sections  40  and  42  are located on opposite sides of window  52  along the path that item  30  would take across weigh plate  22  and under which EAS system  16  and/or RFID system  18  are most likely to be located. Sections  40  and  42  are made of a non-metallic but durable material, such as various grades of thermoplastic or thermoset plastics. These materials are sufficiently rigid and resistant to scratching and chemical degradation to make them suitable substitutes for metal. Sections  40  and  42  may be fabricated by molding thermoset components in liquid form and then curing them, for example, by applying heat. Plastics are also more transparent to electromagnetic energy than metals. 
         [0024]    Sections  40  and  42  may be substantially transparent to all electromagnetic fields from EAS system  16  and RFID system  18 , thus permitting designers of such systems to optimize the effectiveness of electromagnetic fields for their intended use and minimize safety concerns. 
         [0025]    Materials other than plastics that are also resistant to scratching and chemical degradation and that are more transparent to electromagnetic fields than metal are also envisioned. 
         [0026]    Sections  44  and  46  may include metal for rigidity and durability. 
         [0027]    At customer request, sections  40 - 46 , including fence  52 , may be produced in different colors or color schemes, for customer brand promotion, for example. 
         [0028]    Sections  44  and  46  may include channels  48  for directing spilled liquids. For example, channels  48  may be oriented from a leading side of item checkout device  10  to a trailing side of checkout device  10 , relative to the path of items  30  during scanning. 
         [0029]    Since weigh plate  22  uses less metal, it costs less than a traditional metal weigh plate  22 . 
         [0030]    From a top down perspective, weigh plate  22  is generally rectangular in shape. The shapes of sections  40 - 46  is a compromise between metallic and non-metallic preferences. As illustrated, sections  40 - 42  are defined by diagonal lines emanating from the corners of window  50 . Other shapes are envisioned. For example, sections  40 - 42  may be rectangular and longer. As another example, sections  40 - 42  may be combined into a single U-shaped section. 
         [0031]    Window  50  is substantially flush-mounted in weigh plate  22 . Window  50  may be made of glass or other scratch resistant and transparent materials, including combinations of materials. For example, window  50  may be made of glass coated with sapphire for scratch resistance. 
         [0032]    Weigh plate  22  is constructed and assembled in a way that permits substitution of non-metallic sections  40  and  42  if necessary. 
         [0033]    Sections  40 - 46  and window  50  may be assembled with glue and supported at the joints by underlying metal fixtures. 
         [0034]    Weigh plate  22  may include tapered edges to provide a transition to a surrounding checkout counter in which item checkout device  10  may be mounted. 
         [0035]    With reference to  FIG. 3 , an example barcode reader  12  includes laser  62 , mirrored spinner  64 , pattern mirror  66 , collector  68 , and detector  70 . 
         [0036]    Laser  62  produces a laser beam. 
         [0037]    Mirrored spinner  64  directs the laser beam to pattern mirrors  66  to produce a scan pattern, and receives reflected light from item  30  from pattern mirrors  66 . Mirrored spinner  68  is rotated by motor  74 . 
         [0038]    Pattern mirrors  66  direct the laser beam through window  76  towards bar code label  32  and direct the reflected light to mirrored spinner  64 . 
         [0039]    Collector  68  collects the reflected light from mirrored spinner  64  and directs it towards detector  70 . 
         [0040]    Detector  70  converts the reflected light into electrical signals. 
         [0041]    In an alternate example, barcode reader  12  may include two or more windows  76 , and correspondingly may include a plurality of lasers  62 , a plurality of mirrored spinners  64 , a plurality of sets of pattern mirrors  66 , a plurality of collectors  68 , and a plurality of detectors  70  for scanning item  30  from a plurality of additional directions. 
         [0042]    With reference to  FIG. 4 , an example embodiment of item checkout device  10  is illustrated in more detail. In this example embodiment, item checkout device  10  includes two windows  100  and  102 . 
         [0043]    Item checkout device  10  includes a housing  88  including a first housing portion  90  and a second housing portion  92 . First housing portion  90  includes substantially horizontal aperture  94 , including window  100  for scanning item  30  from a first set of directions. First housing portion  90  includes a first set of pattern mirrors  66 . 
         [0044]    Second housing portion  92  includes substantially vertical aperture  96 , including window  102  for scanning item  30  from a second set of directions. Second housing portion  90  includes a second set of pattern mirrors  66 . 
         [0045]    First housing portion  90  includes top piece  98 . Top piece  98  has a top surface and side surfaces to complete the upper part of first housing portion  90 . Top piece  98  is generally U-shaped to fit around aperture  94  on at least three sides and is easily removable from first housing portion  90 . For other item checkout devices, top piece  98  may surround aperture  94  on all four sides. 
         [0046]    Scale assembly  14  is located within first housing portion  90 . Scale assembly  14  is mounted to the bottom surface of top piece  98 . 
         [0047]    Scale assembly  14  includes load cell support member  104 , load cell floating frame  106 , and load cell electrical circuitry  108 . 
         [0048]    Load cell support member  104  provides a platform for mounting load cells  110  and load cell electrical circuitry  108 . Load cell support member  104  is mounted to the bottom surface of top piece  98 . 
         [0049]    Weigh plate support posts  124  fasten to load cells  110 . Besides supporting weigh plate  22 , weigh plate support posts  124  couple load cell floating frame  106  to load cells  110 . Weight plate support posts  124  protrude through apertures  152  in top piece  98 . 
         [0050]    Load cell support member  104  may be made of metal and may be generally U-shaped. Other support member configurations are also envisioned for other readers, including four support members around aperture  94 . 
         [0051]    Load cell support member  104  conveniently borders pattern mirror housing  116  in first housing portion  90  without obstructing scanning light beams from aperture  94  and without interfering with positioning of EAS coil  24  around pattern mirror housing  116 . Since scale assembly components are located above pattern mirrors  66 , pattern mirror housing  116  may be sealed. 
         [0052]    Load cell floating frame  106  counteracts side loads and minimizes corresponding spreading of load cells  110 . The illustrated example of load cell floating frame  106  is generally U-shaped and is made of metal. Other floating frame configurations are also envisioned for other readers, including four floating frames around aperture  94 . 
         [0053]    Electrical circuitry  108  includes connector  136  which couples to a corresponding connector in first housing portion  90 . 
         [0054]    At one end, top piece  98  may be supported by feet  144 . Feet  144  and first housing portion  90  are supported by metal basket  160 . At another end, top piece  98  includes latch ends  146  which rotatably couple to corresponding latch receptacles  150 . 
         [0055]    Weigh plate  22  rests upon load cell support posts  124 . 
         [0056]    Although particular reference has been made to certain embodiments, variations and modifications are also envisioned within the spirit and scope of the following claims.