Abstract:
A method of reading a data transmission from an electronic transmitting device mounted to a vehicle tire assembly includes: positioning a convex upper surface of a stand to intercept a vehicle tire of the vehicle tire assembly; establishing rotational engagement between the vehicle tire and the convex upper surface of the stand to slow the speed of the vehicle and reduce the rotational rate at which the vehicle tire rotates to a targeted reduced rotational read rate; and directing an antenna field from at least one antenna toward an approach path (and at least one antenna toward the exiting path) of the vehicle tire to the convex upper surface and lower surface of the stand to receive data transmission from the electronic transmitting device as the vehicle tire passes over the stand upper surface then down the lower surface at the reduced rotational read rate.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates generally to RFID device readers and, more specifically, to a method of reading tire mounted RFID devices within a read station. 
       BACKGROUND OF THE INVENTION 
       [0002]    Radio frequency identification devices (RFID devices) are useful in association with sundry product categories and have gained widespread commercial importance and acceptance. Such devices generally have memory storage capability for electronically storing product-specific information such as product history and a product identification number. The device further provides an integrated transmitter that transmits responsive to a prompt signal the stored data for receipt by a receiver antenna. For example, it is known to associate an RFID with a vehicle tire or wheel rim assembly in order to access tire, vehicle, and/or wheel related identification and history throughout the lifetime service of the product. 
         [0003]    It is important in any RFID transmission system that the data transmitted by the product-based RFID device be transmitted reliably, expeditiously, and without error to a reader for processing and use. Without a reliable data transmission and reception capability, the integrity of the information downloaded and the utility of the system will be compromised. In a vehicle tire or wheel-based application, the construction of a reliable RFID data transmission system presents numerous application-specific challenges that must be addressed in order to achieve an acceptable level of performance. 
       SUMMARY OF THE INVENTION 
       [0004]    According to an aspect of the invention, a method of reading a data transmission from an electronic transmitting device mounted to a vehicle tire assembly includes: positioning a convex upper surface of a stand to intercept a vehicle tire of the vehicle tire assembly; establishing rotational engagement between the vehicle tire and the convex upper surface of the stand to slow the speed of the vehicle and reduce the rotational rate at which the vehicle tire rotates to a targeted reduced rotational read rate; and directing an antenna field from at least one antenna toward an approach path of the vehicle tire to the convex upper surface of the stand to receive data transmission from the electronic transmitting device as the vehicle tire passes over the stand upper surface at the reduced rotational read rate. 
         [0005]    According to another aspect of the invention, the method includes directing a second antenna field from at least a second antenna toward an exit path of the vehicle tire from the upper surface of the stand to receive data transmission from the electronic transmitting device as the vehicle tire passes over the stand upper surface at the reduced rotational read rate. 
         [0006]    In yet another aspect, the method includes tilting the directionally aimed first and second antenna fields at an acute tilt angle within a range of 13 to 15 degrees toward the approach and exit paths, respectively, of the vehicle tire relative to the stand upper surface. The first and second antenna fields may, in another aspect, be positioned to place the transmitting device into a continuously coupled relationship with at least one of the first and second antenna fields as the vehicle tire passes across the convex upper surface. 
         [0007]    According to a further aspect, the method includes mounting the transmitting device to the vehicle tire assembly to rotate with the tire; and configuring the height and concavity of the upper convex surface to operatively require the tire and the transmitting device to substantially complete at least one revolution at the targeted reduced rotational read rate as the tire passes over the upper convex surface span. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The invention will be described by way of example and with reference to the accompanying drawings in which: 
           [0009]      FIG. 1A  is a schematic representation of an antenna and the field generated therefrom with a transmitting device approaching the antenna; 
           [0010]      FIG. 1B  is a schematic representation of the antenna of  FIG. 1A  tilted toward the approaching transmitting device. 
           [0011]      FIG. 2  is a top perspective view of an antenna assembly configured pursuant to the invention. 
           [0012]      FIG. 3  is an exploded bottom perspective view of the antenna assembly of  FIG. 2 . 
           [0013]      FIG. 4A  is a schematic representation of a vehicle tire initial travel over the antenna assembly. 
           [0014]      FIG. 4B  is a schematic representation of a the vehicle tire traveling over a rearward surface portion of the antenna assembly. 
           [0015]      FIG. 5  is a schematic representation of a read station in which four antenna assemblies are positioned to intercept four vehicle tires and transmit downloaded data from the transmitting devices in the tires to a remote data processing computer. 
           [0016]      FIG. 6  is a top perspective view of a center unit of an alternative embodiment of an antenna assembly configured pursuant to the invention. 
           [0017]      FIG. 7  is a partially exploded bottom perspective view of the center unit. 
           [0018]      FIG. 8  is a bottom partially exploded view of the three unit alternative antenna assembly embodiment. 
           [0019]      FIG. 9  is a schematic representation of a read station in which four three-component antenna assemblies are positioned to intercept truck tires and transmit downloaded data from the transmitting devices in the tires to a remote data processing computer. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    Referring to  FIGS. 1A and 1B , a schematic of an antenna system  10  is shown including an antenna  12  positioned flat on a ground surface  14 . The antenna  12  generates a field or beam pattern  16  for the purpose of receiving data transmission signals  20  from an approaching electronic device  18 . Device  18  is of a type commercially available and used, such as a radio frequency identification (RFID) tag. The tag  18  may be mounted to a product that moves toward and away from a read station in which the antenna  12  and its generated beam pattern  16  is situated. The speed at which the tag  18  approaches and leaves the vicinity of the antenna  12  will affect the time interval in which the transmitted data  20  is received by the antenna field  16 . The read range of the antenna  12  is increased and represented by the shaded region  17  of the field  16 . A maximized read range will positively affect the coupling efficiency between the transmitted signal  20  and the antenna field  16  and serve to promote a complete and accurate data transmission as the tag approaches and leaves the vicinity of the antenna  12 . 
         [0021]      FIG. 1B  shows an alternative antenna position within a read station in which the antenna  12  is tilted toward the approach path of the tag  18 . Tilting of the antenna  12  at an acute angle α with respect to the ground surface  14  will cause the beam pattern  16  to tilt at angle α toward the approach path (represented by data transmission  20 ) of the tag  18 . The tilting of the field  16  toward the approach path of the tag  18  serves to enlarge the read field  17  as shown by the larger shaded region of  FIG. 1B  as compared with the shaded region of  FIG. 1A . The read range of the antenna  12  is thus maximized by introducing a mechanical tilt at angle α. The enlargement of the read range  17  effected by mechanically tilting the antenna  12  improves the reliability of the system and ensures that transmitted data will be captured as the tag  18  moves through the read zone. With the mechanical tilt, more of the cross-sectional area of the antenna pattern  16  is available and improved transmission efficiency is gained. 
         [0022]    With reference to  FIGS. 2 and 3 , a tilted antenna system stand  22  is shown to include a stand freestanding base  24  supported by elongate support legs  26 ,  27 ,  28 , and  29 . The support legs affix to an underside of the base  24  along outer peripheral locations and for support of the base on a ground surface. The stand  22  is provided with a cover  30  having a convex profile that covers the top of the base  24 . As used herein, “convex” is meant in a general sense. The cover upper convex surface may be composed of adjoining flat surface segments or be continuously radiussed as shown. The base is formed of any suitably strong material such as plastic, and is configured having a protruding latch finger  32  and latch slot  33  spaced apart along each side of the stand. The finger  32  is shaped to interlock with the slot  33  of a like-configured unit to thereby chain multiple stands together in a series. The stand cover  30  is of convex sectional configuration, formed to include a forward inclined surface  34  extending to an apex or crown  36 , and a rearward inclined surface  38  extending from the crown  36  to a rearward side of the stand. A matrix of cross-ribs  40  may be molded into the underside of the base  24  for adding strength to the structure. 
         [0023]    The cross-ribs  40  define a forward antenna receiving recess  42  with support notches  44  formed in ribs along the sides of the recess  42 . A similarly configured rearward antenna receiving recess  46  is positioned between the cross-ribs  40  of the rearward portion of the base, likewise providing support notches  48  formed in ribs along the sides of the rearward recess  46 . A forward antenna  50  is sized to fit within the forward recess  42 , resting upon notches  44 . A rearward antenna  52  is positioned within rearward recess  46  and rests upon the notches  48 . The notches  44 ,  48  formed within the cross-ribs  40  form an angled seat within the recesses  42 ,  46  such that the antennae  50 ,  52  when positioned within the recesses are at an acute angle with respect to a vertical centerline of the stand  22 . The antennae  50 ,  52  angle in opposite directions from the centerline at an acute angle α (see  FIG. 1B ) which is preferably between 13 to 15 degrees, although angles of different magnitudes may be used respectively for the two antenna in order to create the antenna field desired. 
         [0024]    It will be appreciated that the cover  30  is formed of RF transparent material and serves to enclose the antennae  50 ,  52  in their angled position within the stand. Assembly posts  54 ,  56  mate within sockets formed in the cover to attach the cover to the base  24 . The antennae  50 ,  52  are angled within the ground surface  14  in  FIGS. 1A and 1B  at the aforementioned acute angle which may be the same for each antenna or different, depending on the system objectives and requirements. In the assembled condition, the antennae  50 ,  52  generally reside beneath the inclined RF transparent surfaces  34 ,  38 , respectively. The angle of inclination of the antennae  50 ,  52  and the surface portions  34 ,  38  may be the same or differ. The stand assembly  22 , it will be appreciated, produces a speed bump when the stand is positioned to intercept the wheels of an oncoming vehicle. The tires of the vehicle are intended to ride up the forward surface  34 , over the crest or apex  36 , and down the rearward inclined surface  38 . The slopes of inclined surface  34 ,  38  are designed to create a bump of desired severity so that a vehicle traveling over the stand  22  will be slowed to an objective read speed. Thus, the slope of the inclined surfaces  34 ,  38  may be more or less than the slope of the inclined antennae  50 ,  52  within the stand, depending on the degree of bump necessary to slow the oncoming vehicle to an objective read speed. 
         [0025]      FIGS. 4A and 4B  illustrate the operation of the speed bump created by the stand  22  and the tilted antenna  50 ,  52  positioned within the stand as a vehicle tire  58  rides up, over, and down the stand surfaces  34 ,  36 ,  38 . The tire  58  includes a sidewall  60  and mounts to a rim  62  in standard fashion. An RFID tag  64  is secured to the tire  58  by conventional means at a conventional location such as to the tire inner liner (not shown) defining the tire cavity. So positioned, the tag  64  rotates with the tire  58  at the same speed of rotation. An antenna beam pattern  68  from the forward antenna  50  is tilted toward the tire  58  approach path as the tire engages and rolls up the inclined surface  34  of the stand  22 . The tilt of the antenna  50  within the stand  22  tilts the field  68  so as to allow the signal from the tag  64  access to more of the field cross-section as tag  64  rotates with the tire. The second, rearwardly mounted antenna  52  is likewise tilted within the stand in the opposite (rearward facing) direction from the forward (forward facing) tilted antenna  50 . The field or beam pattern  66  is thus tilted to the rear by the generally same angle α as the forward beam pattern  68  from antenna  50  tilts forward. It is preferred, although not necessary, that the acute tilt angle α be within the range of 13 to 15 degrees. 
         [0026]    The position of the antenna  50  relative to the antenna  52  is close enough such that the beam patterns  66 ,  68  overlap to a minimal extent and cover without a gap the area above the stand  22 . Thus, the tag  64 , mounted to the tire  58 , will rotate over the surfaces  34 ,  36 ,  38  with the tire and complete a revolution with the tire  58  within the time interval required for the tire to move over a stand and/or multiple antenna component assemblies  70  as shown in  FIGS. 5 and 9 . As the tag rotates, data transmission by the tag will intersect the beam patterns  66 ,  68  of one or both of the antenna  50 ,  52 . A reliable and complete transmission of data is thereby assured. 
         [0027]    Moreover, the speed at which the tag  64  rotates with the tire  58  may be controlled by controlling the front to rear span and/or degree and/or extent of incline of the speed bump represented by surfaces  34 ,  36 , and  38  of the stand  22 . A higher angle of tilt of the forward and rearward surface or lengthening the surfaces  34 ,  36 , and/or  38  raises the “bump” and will generally obligate the driver of the vehicle to slow down to a greater extent. This, in turn, slows the rotational speed of the tire and tag  64  over the stand  22  and elongates the time period (read interval) during which the tag transmission may be communicated to the antenna patterns  66 ,  68 . Conversely, lowering the “bump” by adjusting the angle of tilt and/or width of stand surfaces  34 ,  36 , and  38  will obligate a driver to slow the vehicle to a lesser extent. The read interval between the tag  64  and the beam patterns  66 ,  68  will be reduced accordingly. By adjusting the size (span) and/or tilt of the stand surfaces with the tilt of the antenna beam patterns, an optimal read interval may be attained that is long enough to effect a highly reliable data transmission without slowing the vehicle unnecessarily. 
         [0028]    The tag  64  may be mounted to the inner liner of the sidewall of the tire  58  as explained. For such a mounting location, it may be beneficial to mount the antenna  50 ,  52  to a side of the tire  58  for improved coupling between the antenna beam pattern and the data transmission from the tag. To facilitate mounting the antenna to a side of a tire traveling over the stand, a bridging unit  72  may be utilized in a three-component stand assembly  70  such as that shown in  FIGS. 6 ,  7 , and  8 . The tire is intended to ride directly over the bridging unit upper convex surface. The bridging unit  72  is situated between two antenna assemblies of the type described previously. The center or bridging unit  72  includes a body  74  having cross-rib reinforcement  76  and a convex upper surface  78 . A pair of elongate support legs  80 ,  82  affix to an underside of the body  74  and support the body on a ground surface. A socket  84  connects the body  74  to the ground surface  14  in  FIGS. 1A and 1B . The cover provides the arched or convex outer surface  78  and includes a forward inclined surface  86  and a rearward inclined surface  88 , separated by an apex region  87 . The forward and rearward surfaces  86 ,  88  have an acute tilt angle generally the same as the forward and rearward surfaces of the cover  30  ( FIGS. 2 and 3 ) described previously. The bridging unit body  74  is formed to provide a latch finger  92  and a latch slot  90  along each longitudinal side that mate and interconnect with the latch  32  and latch slot  33  of the base  24 . Accordingly, a three component series may be interconnected consisting of two antenna stands  22  on opposite side of a single bridging stand unit  72  as shown in  FIG. 8 . The center or bridging unit surfaces  86 ,  88  are targeted by a vehicle operator and tire  58  rides up and over the center unit during a drive-through read operation. 
         [0029]    The incline of the surfaces  86 ,  88  complement the incline of surfaces  34 ,  38  of the antenna assembly  22 . In the three component version of the invention, the two antenna assemblies  22  on opposite sides of the center unit  72  are to the side of the tire  58  and function to ensure that a complete and accurate data transmission between the tag  64  and the antenna  50 ,  52  will occur. The tilt of the antenna  50 ,  52  within each of the antenna assemblies  22  on opposite sides of the center unit  72  is generally the same, and it is preferred that the tilt angle be generally 13 to 15 degrees although more or less tilt may be employed if desired. 
         [0030]    With reference to  FIGS. 4A and 4B , the tag  64  rotates with the tire  58 . It is desirable to slow the vehicle by means of the speed bump formed of one or two antenna stand assemblies  22  and, if desired, bridging unit  72 . A single antenna stand assembly may be employed if it is preferred that the tire ride directly over the convex surface of RFID transparent cover  30 . If an adjacent position of the antenna  50  and/or  52  is desired, stand assembly  22  may be used with a bridging unit  72 . The tire rides over the bridging unit  72  in such a configuration with the antenna members  50 ,  52  positioned to the side. It is preferable that the speed bump configuration slow the rotational rate of the vehicle tire  58  to a targeted reduced rotational read rate optimal for effecting reliable data transmission as the tire passes over the convex upper surface. The size, shape and height of the bump will be selected to induce the vehicle operator to lower the speed of the vehicle to achieve the targeted reduced rotational read rate speed. The span and degree of incline created by surfaces  34 ,  36 ,  38  or, surface  86 ,  87 , and  88  if a bridging unit  72  is employed, is constructed to operatively require the tire and the transmitting device  64  to at least complete one revolution over a stand and/or multiple antenna component assemblies  70  as shown in  FIGS. 5 and 9  at the targeted reduced rotational read rate speed as the tire traverses over the bump. The fields  66 ,  68  are established above the tire path across the path in such a manner so as to continuously maintain the tag within one or the other or both of the fields  66 ,  68  as the tire rotates at the reduced read rate speed across the bump. In so doing, data transmission between the tag and the antenna fields is continuous and highly reliable and accurate transmission of data is facilitated. 
         [0031]      FIGS. 5 and 9  illustrate the deployment of a three-component antenna assembly system into a read station for a passenger car ( FIG. 5 ) station and for a cargo truck drive-through station ( FIG. 9 ). In  FIG. 5 , four three-component assemblies  70  are positioned to intercept the four tires on a passenger car and form a drive-through read station. The car is driven through the station and the vehicle tires encounter the four stand assemblies generally simultaneously. The driver steers the tires toward and over the center unit  72  of each three-component stand and, upon encountering the four “bumps”, slows the vehicle to an optimal read speed. As the tires travel over the center units  72 , respectively, the two antenna assembly units  22  on opposite sides of each center unit engage the tag on each tire and data transmission from the tag to the antenna within each unit  22  is established and completed. At the reduced vehicle speed caused by the speed bumps, the optimal time interval required to effect complete data transmission is achieved. Data downloaded to the antenna may then be conducted by wiring  100  to a transmitting device  102  for wireless data transmission to a processing computer  104 . 
         [0032]    In  FIG. 9 , four three-component assemblies  70  are positioned to intercept the tires on a cargo truck and form a drive-through read station. The truck  94  may have a pair of forward tires and dual tandem tires in the rear as shown. The truck  94  is driven through the station and the vehicle tires encounter the four stand assemblies  70  generally simultaneously. The driver steers the tires toward and over the center unit  72  of each three-component stand  70  and, upon encountering the four “bumps”, slows the vehicle to an optimal reduced read speed with each tire rotating at least one revolution at the reduced read speed over a respective bump. As the tires travel over the center units  72 , respectively, the two antenna assembly units  22  on opposite sides of each center unit engage the tag of each tire and data transmission from the tag to the antenna within each unit  22  is established and completed. At the reduced vehicle speed caused by the speed bumps, the optimal time interval required to effect complete data transmission is achieved. The tandem tires in the rear of the truck  94  may be read simultaneously as the tires pass over the center bridging unit  72  by the two assemblies  22  positioned to the side of the unit  72 . Data downloaded to the antenna may then be conducted by wiring  100  to a transmitting device  102  for wireless data transmission to a processing computer  104 . 
         [0033]    With reference to  FIGS. 4A and 4B  and  9 , as described previously, the bumps created by the assemblies  70  are configured to slow the vehicle to a lower speed that will allow the tags  64  in  FIGS. 4A and 4B  and tags  18  and  20  in  FIG. 9  to rotate at least one complete revolution as the tire carrying the tag passes over a stand and/or multiple antenna component assemblies  70  as shown in  FIGS. 5 and 9  through the fields created by antenna  50 ,  52 . The fields created by antenna  50 ,  52  are positioned to keep read contact with the tag throughout its revolution over the speed bump to insure a reliable and accurate data transmission. The tilt of the antenna  50  orients its field pattern toward the tire as the tire engages and rides up onto the assembly  70  and the tilt of antenna  52  orients its field pattern toward the tire as the tire travels down a rearward surface portion of the assembly  70  and exits. 
         [0034]    Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.