RFID Multi-Read Portal

• US 20190311164A1
• Filed: 12/27/2018
• Published: 10/10/2019
• Est. Priority Date: 04/09/2018
• Status: Active Grant

• Current Assignee: Fujitsu Frontech North America Incorporated (Fujitsu Limited)
• Original Assignee: Fujitsu Frontech North America Incorporated (Fujitsu Limited)
• Inventors: Teter, Aaron, Markman, Herbert, Markman, Jeffrey, Nagayumi, Shinichi, Dalton, Daniel G.
• Granted Patent: US 10,783,339 B2
• Time in Patent Office: Days
• CPC Class Codes: G06K 7/10079 the collision being resolved in the spatial domain, e.g. temporary shields for blindfolding the interrogator in specific directions
• CPC Class Codes: G06K 7/10415 the interrogation device being fixed in its position, such as an access control device for reading wireless access cards, or a wireless ATM banking machines in general G07F19/00
• CPC Class Codes: G06K 7/10425 the interrogation device being arranged for interrogation of record carriers passing by the interrogation device

Abstract

An RFID portal reads multiple associated RFID tags on articles in groups moved through an RFID code reader having interrogation/charging and receiving/detection antennas concentrated on the group when in a reading zone. The articles are movable through a passage between the reading zone and an outside area. The passage has conductive walls at the reading zone associated with antennas for applying and collecting focused RF signals, and the walls define a vestibule lined with broadband or specific stopband electromagnetic damping structures as well as elongating signal paths into and/or out of the reading zone. Attenuation by one or more of broadband and stopband damping and signal path elongation can achieve 10 dB attenuation or more, sufficient to minimize interaction with stray RFID tagged articles that may be outside of the group in the reading zone.

Claims

1. An apparatus for multi-reading RFID codes carried by articles in a group, comprising:

an RF code reader including interrogation and response detection antennas directed inwardly into a shielding enclosure configured to concentrate RF signals in a reading zone, with controls for applying an RF charging signal in at least one predetermined frequency band and discerning RFID codes from responsive signals received from tagged articles in the group;

wherein at least one passage is provided to the shielding enclosure, through which the articles are movable between the reading zone and an area outside of the shielding enclosure; and

a conductive wall with at least one surface facing into the passage, wherein the conductive wall is structured for attenuating electromagnetic energy at least in the predetermined frequency band so as to limit effective interaction with any stray RFID tagged articles outside the shielding enclosure by at least one of a lossy material in the conductive wall damping electromagnetic propagation, a bandstop structure on the conductive wall facing into the passage for damping propagation in the frequency band, and by reflection of the RF signals along a path that is elongated by reflections against the conductive wall.

2. The apparatus of claim 1, wherein the passage extends through an elongated vestibule leading into the reading zone, and the conductive wall defines a length of at least one of a sidewall, top wall and bottom wall of the vestibule.

3. The apparatus of claim 1, wherein the passage extends through an elongated vestibule leading into the reading zone, and the conductive wall defines a length extending along at least two opposite sidewalls of the vestibule, including a focusing portion at the reading zone defining at least one of a clamshell shape, a parabolic shape, a Fresnel configuration and a meta-material.

4. The apparatus of claim 1, wherein the damping structure comprises at least one of a Salisbury composite surface, a broadband RF attenuating material, an attenuating structure and a geometry that elongates one or more propagation paths between the reading zone and an outside, configured to attenuate electromagnetic reflection at an RFID frequency band.

5. The apparatus of claim 4, wherein the damping structure attenuates electromagnetic propagation between the RF code reader and the stray RFID tagged articles by at least 10 dB.

6. The apparatus of claim 1, wherein the damping structure is configured to damp electromagnetic reflection at a frequency within a UHF RFID frequency band of substantially 860 to 960 mHz.

7. The apparatus of claim 1, wherein the conductive wall is electromagnetically reflective at the reading zone and configured to transmit direct RF energy and reflected indirect RF energy between the antennas and the RFID codes carried by articles in the group of articles when in the reading zone.

8. The apparatus of claim 1, wherein the passage and the shielding enclosure are configured to accommodate a shopping cart.

9. A method for multi-reading RFID codes carried by articles, comprising the steps of:

associating the articles in groups of plural articles in proximity to one another for multi-reading the RFID codes;

moving the groups successively into an RF code reader including interrogation and response detection antennas directed inwardly into a shielding enclosure configured to concentrate RF signals in a reading zone accommodating the groups, and processing the groups by applying an RF charging signal in at least one predetermined frequency band and discerning RFID codes from responsive signals received from tagged articles in the group;

limiting at least one of a residence time during which the groups remain in the reading zone and a processing time during which the interrogation and response antennas are active, to a time only sufficient to process a substantial majority of RFID codes in the groups.

10. The method of claim 9, further comprising limiting at least one of an amplitude of the charging signal, sensitivity of reception of the responsive signals, and time of application of the charging and responsive signals to be only sufficient to process a substantial majority of RFID codes in the groups.

11. The method of claim 9, associating articles in groups comprises at least one of carrying the groups of plural articles in respective containers and supporting the groups on at least one powered movable conveyance.

12. The method of claim 9, comprising varying the residence time during which the groups remain in the reading zone for interrogation of the RFID codes.

13. The method of claim 12, comprising varying the residence time during which the groups remain in the reading zone by at least one of signaling a human operator for one of speeding up, slowing, pausing, stopping movement of the containers and controlling an operational speed of the movable conveyance.

14. The method of claim 12, wherein the containers comprise at least one of bins, bags, slings and rolling carts.

15. The method of claim 9, further comprising moving the groups to and from the reading zone through at least one passage into the shielding enclosure, from an area outside of the shielding enclosure;

further comprising providing a conductive wall along the passage with at least one surface facing into the passage and carrying an electromagnetic damping structure configured to attenuate electromagnetic energy at least in the predetermined frequency band.

16. The method of claim 15, comprising attenuating the electromagnetic energy in a stopband encompassing the predetermined frequency band using a Salisbury damping configuration having a conductive surface spaced from a conductive backplane by a distance determined from a wavelength of the predetermined frequency band.

17. The method of claim 15, comprising variably limiting at least one of said residence time, said processing time, said amplitude of the charting signal, said sensitivity of reception of the responsive signals, and a time of application of the charging and responsive signals, according to at least one of a predicted time to process said substantial majority for successive ones of the groups, and an empirical rate of processing based on a rate of reading a preliminary sampling of the RFID codes in the successive groups.