Dual antenna for magnetic markers
First Claim
1. A dual antenna capable of energizing a correctly oriented, closely coupled marker providing an identifiable signal in response to an applied magnetic interrogation field and receiving the response, for utilization in card readers, product verification devices, or the like, comprising:
- a substantially flat elongated drive coil defining a longitudinal axis of the antenna, each individual winding of the drive coil extending in a plane substantially perpendicular to said longitudinal axis; and
a receive coil having a plurality of loops of differing lengths in the direction of the longitudinal axis of the antenna, a first portion of each of said loops being overlapped by said drive coil, said first portion extending in a direction substantially perpendicular to the longitudinal axis of said antenna, said plurality of loops being operataive to decrease the longitudinal position sensitivity of the antenna in relation to the marker.
8 Assignments
0 Petitions
Accused Products
Abstract
A dual antenna is provided for energizing and receiving a response from a closely coupled marker providing an identifiable signal. An elongated drive coil is wound on a substantially flat winding template and defines a longitudinal axis of the antenna. Each winding of the drive coil extends in a plane substantially perpendicular to the longitudinal axis. A receive coil has at least one elongated loop extending substantially parallel to the antenna axis with a first portion of the loop being overlapped by the drive coil; said first portion extending substantially perpendicular to the longitudinal axis of the antenna. One portion of the receive coil is outside the drive coil; the drive coil being substantially the same length as the marker with the receive coil being substantially as wide as the marker to optimize the signal. In one embodiment, a plurality of receive coil loops is provided to decrease the longitudinal sensitivity. Preferably, the winding template includes a U-shaped slot for receiving the first portion of the receive coil and a reduced section to receive the second portion. The template is preferably magnetic barium ferrite mixed with a plastic binder to provide a dc bias field for activation the marker. In additional embodiment, multiple receive coils are provided side-by-side to allow simultaneous reading of multiple ribbon marker.
21 Citations
24 Claims
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1. A dual antenna capable of energizing a correctly oriented, closely coupled marker providing an identifiable signal in response to an applied magnetic interrogation field and receiving the response, for utilization in card readers, product verification devices, or the like, comprising:
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a substantially flat elongated drive coil defining a longitudinal axis of the antenna, each individual winding of the drive coil extending in a plane substantially perpendicular to said longitudinal axis; and a receive coil having a plurality of loops of differing lengths in the direction of the longitudinal axis of the antenna, a first portion of each of said loops being overlapped by said drive coil, said first portion extending in a direction substantially perpendicular to the longitudinal axis of said antenna, said plurality of loops being operataive to decrease the longitudinal position sensitivity of the antenna in relation to the marker. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A dual antenna capable of energizing a correctly oriented, closely coupled marker providing an identifiably signal in response to an applied magnetic interrogation field and receiving the response, for utilization in card readers, product verification devices, or the like, comprising:
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a substantially flat elongated drive coil defining a longitudinal axis of the antenna; a receive coil having a plurality of loops of differing lengths in the direction of the longitudinal axis of the antenna to decrease the longitudinal position sensitivity of the antenna in relation to the marker, and a substantially flat plate adjacent said coils and forming a part of said antenna; said plate including magnetic material to provide a dc bias to activate said marker. - View Dependent Claims (23, 24)
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Specification