Frequency selective surface aids to the operation of RFID products

• US 8,514,079 B2
• Filed: 06/24/2010
• Issued: 08/20/2013
• Est. Priority Date: 12/20/2006
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Knadle, Richard T. Jr., Duron, Mark
• Primary Examiner(s): Nguyen, Tai T
• Application Number:
  US12/822,678
• Publication Number:
  US 20100259365A1
• Time in Patent Office: 1,153 Days
• Field of Search: 3405721-5728, 340/10.1, 340/10.2, 340/5.6, 343/878, 343/909
• US Class Current: 340/572.1
• CPC Class Codes: G06K 17/0029 the arrangement being specially adapted for wireless interrogation of grouped or bundled articles tagged with wireless record carriers
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles
• CPC Class Codes: G06K 7/10435 the interrogation device being positioned close to a conveyor belt or the like on which moving record carriers are passing conveying in accordance with bodily destination marks, see B65G47/46, sorting of objects carrying identity markings, see B07C5/34
• CPC Class Codes: H01Q 1/2208 associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems methods or arrangements for sensing record carriers, e.g. for reading patterns G06K7/00; record carrier for use with machines and with at least a part designed to carry digital markings G06K19/00
• CPC Class Codes: H01Q 15/0013 said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective

Abstract

The present invention is directed to systems that use frequency selective surfaces (FSS) to aid in the operation of radio frequency identification (RFID) devices and products. In one embodiment, a system for interrogating radio frequency identification (RFID) tags includes a conveyor belt and an RFID reader. The conveyor belt has a first surface and a second surface. The first surface is configured to receive an item to which an RFID tag is affixed and the second surface is configured to slide on a metal slide plate. The RFID reader is configured to transmit instructions embodied in a radio frequency (RF) signal to the RFID tag, wherein the metal slide plate is positioned between the RFID reader and the RFID tag and comprises a frequency selective surface that is substantially transparent to the RF signal.

Claims

1. A system for interrogating radio frequency identification (RFID) tags, comprising:

a conveyor belt having a first surface and a second surface, wherein the first surface is configured to receive an item to which an RFID tag is affixed and the second surface is configured to slide on a metal slide plate; and

an RFID reader antenna, coupled to an RFID reader, configured to transmit instructions embodied in a radio frequency (RF) signal to the RFID tag;

wherein the metal slide plate is positioned between the RFID reader antenna and the RFID tag, and wherein the metal slide plate comprises a frequency selective surface that results in the metal slide plate being substantially transparent to the RF signal.

2. The system of claim 1, wherein a structure of the frequency selective surface comprises at least one of a dipole, a tripole, an end-loaded tripole, a cross pattern, a square spiral, and a loop.

3. The system of claim 2, wherein the structure of the frequency selective surface is filled with a dielectric material.

4. The system of claim 3, wherein the dielectric material is a plastic or a ceramic.

5. The system of claim 1 further comprising a plurality of RFID reader antennas that are dispersed laterally along the metal slide plate.

6. The system of claim 5, wherein the RFID reader performs a sequential antenna reading protocol.

7. The system of claim 1 further comprising a plurality of RFID reader antennas that are dispersed longitudinally along the metal slide plate.

8. The system of claim 7, wherein the RFID reader performs a sequential antenna reading protocol.

9. The system of claim 1, wherein the conveyor belt is disposed in a substantially inclined orientation.

10. The system of claim 1, wherein the conveyor belt is disposed in a substantially declined orientation.

11. The system of claim 1 further comprising a drum turn-around configured to rotate and cause the conveyor belt to move such that there is no relative motion between the drum turn-around and the conveyor belt.

12. The system of claim 1, wherein the system is implemented in an airport or a warehouse.