Apparatus and method for detecting metallic objects in shoes

• US 8,278,921 B2
• Filed: 09/28/2009
• Issued: 10/02/2012
• Est. Priority Date: 11/14/2006
• Status: Expired due to Fees

• Current Assignee: Morpho Detection LLC (Smiths Group International Holdings Ltd.)
• Original Assignee: Morpho Detection (Safran SA)
• Inventors: Crowley, Christopher
• Primary Examiner(s): SHRIVASTAV, BRIJ B
• Application Number:
  US12/568,544
• Publication Number:
  US 20100134102A1
• Time in Patent Office: 1,100 Days
• Field of Search: 324300-322, 324/228, 324/243, 340/551, 3406939-69312, 108/107
• US Class Current: 324/300
• CPC Class Codes: G01V 3/101 by measuring the impedance of the search coil; by measuring features of a resonant circuit comprising the search coil measuring impedance or characteristics derived therefrom G01R27/00, e.g. quality factor G01R27/26

Abstract

An inspection system positions a balancing shim to asymmetrically balance a magnetic field generated by an inductive sensor, which forms part of the inspection system. Additionally, relays and capacitors used to tune the inductive sensor to a desired resonance frequency are geometrically arranged to minimize electrical interference generated by operation of the relays and capacitors. A shielding device, which may be formed on a printed circuit board, protects a magnetic field generated by the inductive sensor from external electromagnetic interference. A slot positioned in the inductive sensor may be used to tune a resonant mode of the inductive sensor to accurately and particularly detect metallic shanks and/or other metallic objects in shoes, socks, and/or clothing.

Claims

1. A method for operating an inspection system, comprising:

exciting one or more metal detector conductive traces of the inspection system with electromagnetic signals at a pre-determined resonance frequency that corresponds to a characteristic resonance frequency of a pre-determined alarm object;

generating a magnetic field in response to the electromagnetic signals; and

determining whether the alarm object is positioned within the inspection system based on the magnetic field.

2. The method of claim 1, wherein the inspection system includes one or more conductive traces that are electrically insulated from the one or more metal detector conductive traces, said method further comprising:

detecting in the one or more conductive traces a resonance signal from the alarm object within the inspection system.

3. The method of claim 2, wherein the alarm object includes a metal shoe shank, exciting one or more metal detector conductive traces further comprises exciting the one or more metal detector conductive traces with electromagnetic signals at a pre-determined resonance frequency that corresponds to a characteristic resonance frequency of the metallic shoe shank.

4. The method of claim 3, further comprising detecting a disruption in the magnetic field caused by the metallic shoe shank positioned within the scanning area of the inspection system.

5. The method of claim 2, further comprising asymmetrically balancing the magnetic field.

6. The method of claim 2, further comprising:

analyzing the resonance signal using a computer processor; and

outputting as a result of analysis by the computer processor an indication of whether the alarm object is present.

7. The method of claim 2, further comprising detecting a presence of an item within a scanning area of the inspection system, the presence of the alarm object associated with the item.