MXPA00003627A - Rfid conveyor antenna - Google Patents

Abstract

An RFID antenna system is described, comprising an elongated antenna (12) proximate an interrogation path (A1-A4) for interrogating transponders (10) moving along the interrogation path. The antenna (12) is oriented such that the longitudinal axis of the antenna is substantially perpendicular to said interrogation path. The antenna provides an active RF interrogation zone that intersects at least 40%of the horizontal longitudinal plane of the interrogation path.

Description

IDRF TRANSPORTING ANTENNA FIELD OF THE INVENTION - _ The present invention relates generally to radio frequency identification devices (IDRF), and more particularly to an IDRF antenna. BACKGROUND OF THE INVENTION ** - - IDRF systems are well known in the art. These systems include relatively large packages containing systems of battery-operated transmission and reception circuits, such as the identification system disclosed in U.S. Patent No. 4,274,083, for passive systems in which the responding transmitter receives its power of the base station or interrogator, such as the identification system disclosed in U.S. Patent No. 4,654,658 A typical IDRF system is made up of transmitters "reusable responders or fixed contacts to or embedded in product carriers, an antenna system which interrogates the contacts by means of an RF link and a controller. The host system (or computer) performs the "" interface with the controller and directs the interrogation of the contacts. The IDRF antenna system typically employs a high frequency signal to interrogate the contacts and, consequently, the product carriers that move in an interrogation path, such as a conveyor. The antenna system is generally placed near the interrogation path to provide effective communication to and from the contacts. Instead of the antenna it is important for the interrogation and reception of the identification code and other data transmitted to and from the contacts. For example, if a single relatively small antenna is used or if the antenna is placed too far away from the interrogation path, inadequate coverage of the interrogation path will occur. Several attempts have been made to optimize the RF link and, therefore, communication between the antenna and the contacts. In one approach (typically employed), a box antenna of rectangular or square shape is adapted around the conveyor. The observed system has several drawbacks. In particular, the antenna system exhibits one or more dead zones for certain contact positions. For example, there is a dead zone through the same center of the conventional box antenna. If a contact is placed inside a window that is parallel to the conveyor belt and comprises some distance on any of the sides of the axis of the central frame, and maintains this position to the entire reading area of the antenna, the contact will not be read . Moreover, the accuracy and totality of the reading also decreases if several contacts are followed by one another in intimate succession during movement through the conveyor. When the contacts are in intimate succession and relatively far from the reading antenna, the contacts appear to have the same distance from the reading antenna and in this way simultaneous transmissions return. The result of the simultaneous transmission is an intelligible identification code. This is particularly the case in a noisy environment, for which protection is necessary. Therefore, it is an object of the present invention to provide an IDRF antenna system that provides optimum coverage in the interrogation path. Another object of the present invention is to provide an IDRF antenna that is immediately incorporated into a conveyor system to provide accurate interrogation or of fixed or embedded contacts in the product carriers. SUMMARY OF THE INVENTION In accordance with the objects and advantages of the present invention, the IDRF carrier antenna system for communication with at least one mobile transmitter transmitter along an interrogation path comprises an elongated antenna placed near the path of interrogation to interrogate the responding transmitter, the antenna is oriented such that the longitudinal axis thereof is substantially perpendicular to the interrogation path and provides an active RF interrogation zone intersecting at least 40% of the horizontal plane longitudinal of the interrogation path. BRIEF DESCRIPTION OF THE DRAWINGS __ _ __ Other features and advantages will be apparent from the following description of the preferred embodiments of the invention, as exemplified in the accompanying drawings, and wherein the reference characters generally pertain to the same, parts or elements in all views and where: FIGURE 1 is a schematic illustration of a typical IDRF system; FIGURE 2 in a perspective view of an embodiment of the IDRF antenna, according to the invention; FIGURE 3 is a perspective view of the IDRF antenna shown in FIGURE 2 and operatively linked to a main antenna assembly; "FIGURE 4 is a perspective view in pieces of the IDRF antenna shown in FIGURE 2. FIGURE 5 is a schematic illustration of the side view of the IDRF antenna, shown in FIGURE 2 placed in FIG. A conveyor system according to the invention: FIGURE 6 is a vertical view of the IDRF antenna shown in FIGURE 2 placed in a transportation system, FIGURE 7 is a schematic illustration of the radiation pattern of the IDRF antenna, according to the invention, and FIGURE 8 is a perspective view in parts of a second embodiment of the antenna "of IDRF, according to the invention. DETAILED DESCRIPTION OF THE INVENTION The IDRF antenna of the present invention substantially reduces or eliminates the disadvantages and defects associated with antenna systems of prior art. In accordance with the invention, an elongated antenna is positioned near the interrogation path for polling responding emitters moving along the interrogation path. The antenna is oriented such that the longitudinal axis thereof is substantially perpendicular to the interrogation path and provides an interrogation zone of active RF_ (or field component) that crosses at least 40% of the longitudinal horizontal plane of the trajectory. of interrogation. With reference to the first FIGURE No. 1, a simple IDRF read / write system is shown. The system typically comprises one or more transmitting transmitters or contacts 10, at least one antenna 12 for communicating with the contacts 10, and a controller 14 for controlling the communication interface. The host system (i.e. the computer) 16 interfaces with the controller 14 and directs the interrogation of the contacts 10 placed or embedded in the carriers of the product 11 and any subsequent actions by means of parallel, serial or serial communications. transmitting main path 18. As illustrated in FIGURE 1, each antenna 12 is positioned on one side of the interrogation path, indicated by arrows AL-A4, which is defined by conveyor 5. As such, the RF link 17 and therefore the RF active zone is limited. By term "active RF zone", as used herein, this means the zone defined by the effective RF radiation or the electromagnetic field component. Referring now to FIGURE 2, is a perspective view of a first embodiment of the _IDRF antenna of the present invention. According to the invention, the antenna 20 has a substantially elongate housing 21 with a longitudinal axis, marked with X. As illustrated in FIGURE 4, the antenna housing 21 comprises a base 22 and an upper part 30. The base 22 is provided with a circular antenna seat 26 which is positioned near the outer edge 23 of the upper surface of the base 22. As discussed below, the seat 26 is adapted to receive and house the frame antenna 36 in the same. The base 22 also has a wiring access port 28 for receiving the wires or cables of the antenna 38 therethrough. As appreciated by any of the experts in the art, various wiring access means may be employed within the scope of the invention to facilitate connection of the antenna 38 to a controller. As illustrated in FIGURES 3 and 4, the upper portion of the housing 30 has a shape correspondingly similar to the surface of the upper portion 24 of the base 22. The upper portion 30 is attached to the base 22 by conventional means, such as screws, rivets, epoxy or other similar adhesives. According to the invention, the housing 21 may comprise several lightweight materials, such as acrylonitrile butadiene-styrene (ABS), polycarbonate, or polyvinyl chloride (PVC). The housing material, however, must provide minimal interference and / or restriction of the RF radiation of the antenna or the electromagnetic field. In a preferred embodiment, the housing material comprises a polyvinyl chloride (PVC). Referring now to FIGURE 4, an IDRF antenna 20 of the present invention is operatively connected to an RS427j antenna master assembly 40 manufactured and distributed by Escort Memory Systems, Scotts.

Valley, California. The main assembly includes the logic of the antenna and associated circuits. As one skilled in the art can appreciate, because the IDRF antenna system of the present invention includes all the circuits necessary to convert the digital signals received from a controller to high-speed RF signals for the responding emitter or the contacts, and conversely convert the RF signals from the contacts back to digital signals for the controller, numerous controllers with the antenna can be employed. A key feature of the present invention is the ability of the antenna 20 to be placed close to or. be incorporated into a transportation system 5. As illustrated in FIGURES 5 and 6, the antenna 20 is positioned near the interrogation path, which is marked by the arrow A5, of the conveyor 5 to interrogate the contacts 10 and , therefore, the products of the product carriers 11, which move along the interrogation path. According to the invention, the distance between the upper part 30 of the antenna 20 and the horizontal plane defined by the upper surface of the conveyor 7 preferably has a range of about 0 inches to 6 inches, and more preferably 0.030 inches to 2 inches. In the preferred embodiment illustrated in FIGS. 5 and 6, the antenna 20 is positioned between the rollers of the conveyor. As illustrated in FIGURE 5, the antenna 20 is designed and adapted to be placed "between the large rollers 6a or the small rollers 6b. As one skilled in the art can appreciate, various conventional means can be employed to install the antenna 20. between the rollers of the conveyor 5. In a preferred embodiment, the meshing rods 19 are provided to facilitate the installation of the antenna 20 (see FIGURE 3) The rods 19 are designed and adapted to engage the mounting holes (not shown) on the conveyor 5. Referring now to FIGURE 6, according to the invention, the antenna 20 extends in a range of approximately 40% to 100% of the conveyor 5 * As illustrated in FIGURE 7 the antenna 20 thereby provides an active RF interrogation zone (or field component) 10, which projects in a substantially vertical direction and perpendicular to the longitudinal horizontal plane. of the interrogation path, marked by arrow A,. In a preferred embodiment of the invention, the interrogation zone RF 10 crosses at least 95% of the longitudinal horizontal plane of the interrogation path. As a result, the antenna of the invention provides an optimal RF link and, consequently effective interrogation of a plurality of contacts that "move along an interrogation path." Referring now to FIGURE 8, it is shown a second embodiment of the invention, wherein the antenna 42 is incorporated directly into the roller of the conveyor 40. In the observed embodiment, the roller 40 includes an antenna core 44, with the antenna (i.e. antenna coil 42 positioned therein, and an outer roller coating 46. The core 44 is provided with a conventional roller bearing 48 positioned on each side to support and maintain the position 46 of the coating 46 on the core 44. According to the invention, the roller 40 (core 44 and * "" coating 46) may comprise a lightweight high strength material such as acrylonitrile-butadiene-styrene (ABS), polyvinyl chloride (PVC), poly carbonate, urethane, polyethylene terephthalate glycol (PETG) and polystyrene. In a preferred embodiment, the roller 40 comprises ABS. As illustrated in FIGURE 8, the * roll 40 would be positioned near the interrogation path, marked by the arrow A8, and in such orientation that the longitudinal axis Y of the roller 40 is substantially perpendicular to the interrogation path. The roller 40 in this way would similarly provide an active RF interrogation zone that would cross at least 40%, preferably at least 95%, of the longitudinal horizontal plane of the interrogation path.

Claims (9)

1. - An IDRF antenna system for communication with at least one responder transmitter moving along an interrogation path having a substantially horizontal longitudinal plane, comprising: an elongated antenna unit positioned near the interrogation path for interrogating the responding transmitter moving along the interrogation path, the antenna unit including an elongated base having a substantially rectangular inner portion, a substantially flat antenna placed within the base and an upper portion that is. movably engages the housing, the upper part comprises an RF transmitting material, the antenna comprises at least one elongated substantially rectangular metal circuit having a longitudinal axis, the longitudinal axis is placed substantially perpendicular to the interrogation path, the metallic circuit that defines a_ flat surface, the metallic circuit that is substantially concentric with the inner portion of the base, the antenna provides electromagnetic transmission and reception fields projected substantially perpendicular to the flat surface, directed electromagnetic fields. in a substantially vertical direction that crosses at least 40% of the width of the interrogation path.

2. The antenna system of Claim 1, wherein the RF interrogation zone crosses approximately from 40% to 100% of the longitudinal horizontal plane of the interrogation path.

3. The antenna system of Claim 2, wherein the RF interrogation zone crosses approximately 95% of the longitudinal horizontal plane of the interrogation path.

4. The antenna system of Claim 1, wherein the operating distance between the antenna unit and the responding emitter is in a range of 0 inches to 6 inches.

5. The antenna system of Claim 1, wherein the responder emitter comprises decision making circuits and a memory.

6. The antenna system of Claim 5, wherein the responding emitter includes a power source.

7. The antenna system of Claim 1, wherein the antenna unit provides a substantially unidirectional RF interrogation zone.

8. - An IDRF antenna for a conveyor system, the conveyor including a band and a plurality of rollers, comprising: an elongated cylindrical outer roll coating, the coating comprising an RF transmitting material, the coating of roller adapted to come into operative contact with the conveyor belt; an antenna core positioned within the roller coating, the core includes contact points placed at each end of the antenna core adapted and rotatably coupled and supporting the roller coating; the core of the antenna that provides a substantially unidirectional planar active RF interrogation zone.

9. - The IDRF antenna of Claim 8 wherein the RF interrogation zone extends through at least 40% of the width of the conveyor.