PHASE COUPLER FOR ROTATING FIELDS

• US 20090261976A1
• Filed: 04/30/2009
• Published: 10/22/2009
• Est. Priority Date: 06/08/2007
• Status: Active Grant

• Current Assignee: CHECKPOINT SYSTEMS, INC. (CCL Industries Incorporated)
• Original Assignee: CHECKPOINT SYSTEMS, INC. (CCL Industries Incorporated)
• Inventors: Zeng, Kefeng, Oung, Harry
• Granted Patent: US 8,933,790 B2
• Time in Patent Office: Days
• US Class Current: 340/572.200
• CPC Class Codes: G08B 13/2471 Antenna signal processing by receiver or emitter
• CPC Class Codes: G08B 13/2474 Antenna or antenna activator geometry, arrangement or layout loop antennae H01Q1/22
• CPC Class Codes: G08B 13/2477 Antenna or antenna activator circuit
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
• CPC Class Codes: H01Q 7/06 with core of ferromagnetic material H01Q7/02 takes precedence

Abstract

This invention relates to dynamically controlled, electronic article surveillance (EAS) systems whereby an array of antenna elements is digitally phased and actively driven for concurrent transmission, and digitally phased and combined in the receiver unit to improve detection. In particular, the individual frequency and phase of the plurality of the transmit/receive signals are rapidly varied to allow for automated manipulation (steering) of the transmit field pattern and receive field sensitivity. The invention achieves the following features via means of digital phasing and dynamic computer control: sufficient far-field cancellation, null-free detection and uncompromised detection performance regardless of tag'"'"'s orientation while using single transmission drivers to drive entire antenna structures, whether loop antenna or ferrite core antenna, using a phase coupler, thereby allowing more efficient system operation or additional features such as deactivator antenna operation.

Claims

1. An electronic article surveillance system comprising a plurality of antenna structures, each antenna structure including three or more loops and wherein each antenna structure is connected to a single transmission driver wherein said transmission drivers are arranged to drive said loops of said antenna structure in such a way that the vector sum of said electromagnetic fields of said transmission drivers is null in a far field and wherein no vector is separated by another vector by 180°

of phase.

2. The electronic article surveillance system of claim 1 further comprising a plurality of electronics boards and wherein each electronics board has two independent transmission drivers thereon, and wherein one of said transmission drivers drives a first antenna structure and wherein the other one of said transmission drivers drives a second antenna structure.

3. The electronic article surveillance system of claim 2 wherein each of said antenna structures is coupled to said single transmission driver via a phase coupler, said phase coupler converting a transmission driver signal into two distinct phase driver signals for driving a first set of loops and a second set of loops for an antenna structure.

4. The electronic article surveillance system of claim 3 wherein one said two distinct phase driver signals has a phase of 0°

and the other one of said phase driver signals has a phase of 90°

.

5. The electronic article surveillance system of claim 3 wherein each of said two distinct phase driver signals are one-half the power of said transmission driver signal.

6. The electronic article surveillance system of claim 1 further comprising electronics boards and wherein each electronics board has two independent transmission drivers thereon, and wherein one of said transmission drivers drives an antenna structure and wherein the other one of said transmission drivers drives a deactivator antenna.

7. An electronic article surveillance system comprising a plurality of antenna structures, each antenna structure including three or more loops which are wound around an electromagnetic core structure and wherein each antenna structure is connected to a single transmission driver and wherein said transmission drivers are arranged to drive said loops wound around said electromagnetic core structure of said antenna structure in such a way that the vector sum of said electromagnetic fields of said transmission drivers is null in a far field and wherein no vector is separated from another by 180°

of phase.

8. The electronic article surveillance system of claim 7 wherein said electromagnetic core comprises either ferrite ceramic material or a composite ferrous and insulating material to form a ferrite core antenna.

9. The electronic article surveillance system of claim 8 further comprising a plurality of electronics boards and wherein each electronics board has two independent transmission drivers thereon, and wherein one of said transmission drivers drives a first ferrite core antenna and wherein the other one of said transmission drivers drives a second ferrite core antenna.

10. The electronic article surveillance system of claim 9 wherein each of said ferrite core antennas is coupled to said single transmission driver via a phase coupler, said phase coupler converting a transmission driver signal into two distinct phase driver signals for driving a first set of loops and a second set of loops for a ferrite core antenna.

11. The electronic article surveillance system of claim 10 wherein one said two distinct phase driver signals has a phase of 0°

and the other one of said phase driver signals has a phase of 90°

.

12. The electronic article surveillance system of claim 10 wherein each of said two distinct phase driver signals are one-half the power of said transmission driver signal.

13. The electronic article surveillance system of claim 8 further comprising a plurality of electronics boards and wherein each electronics board has two independent transmission drivers thereon, and wherein one of said transmission drivers drives a ferrite core antenna and wherein the other one of said transmission drivers drives a deactivator antenna.