Device and method of detecting metal objects

1. A metal detecting device for the detection of a metal object concealed in shoe or on a leg of a subject, comprising:

a housing with a platform having an upper surface with indication areas thereon for the correct positioning of each of a subject's feet;

left-foot and right-foot electromagnetic coils under the indication areas connected to a power supply via an oscillator and a switch;

an electromagnetic shield divider between the left-foot and right-foot electromagnetic coils;

a detection system for the detection of the placement of the subject's feet on the indication area;

a processing unit for processing signals from the electromagnetic coils and detection system; and

a display connected to the processing unit for displaying a warning signal if metal is detected.

2. A metal detecting device as claimed in claim 1 , wherein said power supply is a DC power source provided by a dedicated power pack.

3. A metal detecting device as claimed in claim 2 , wherein said power supply is rechargeable.

4. A metal detecting device as claimed in claim 1 , wherein said power supply is a mains power supply.

5. A metal detecting device as claimed in claim 1 , wherein said detection system for detection of the correct placement of the subject's feet comprising pairs of IR-LEDs and IR detectors.

6. A metal detecting device as claimed in claim 1 , further comprising two secondary metal detector coils per foot.

7. A method for detecting metal objects concealed in a shoe or on the lower part of a leg of a subject using a device as claimed in claim 1 , comprising the steps of:

a. applying current to a first left-foot electromagnetic coil, and a first right-foot electromagnetic coil in turn for a short time period that is typically several milliseconds and recording eddy current signals therefrom;

b. comparing signal from the first left-foot electromagnetic coil with signal from the first right-foot electromagnetic coil to eliminate effect of background interference;

c. positively detecting the presence of a subject's legs, correctly positioned with respect to said indication on said platform via a detection system;

d. comparing signal obtained from first left-foot electromagnetic coil with signal obtained from first right-foot electromagnetic coil when the presence of a correctly positioned subject's legs have been positively detected on said platform for differences; and

e. displaying presence of any differences on said display.

8. A method for obtaining an indication of mass and position of a metal object connected to a leg of a subject using a system as claimed in claim 6 , comprising the steps of:

a. applying current to a first left-foot electromagnetic coil, and a first right-foot electromagnetic coil in turn, for a short time period that is typically several milliseconds, and recording eddy current signals therefrom;

b. comparing signal from the first left-foot electromagnetic coil with signal from the first right-foot electromagnetic coil to eliminate effect of background interference;

c. positively detecting the presence of a subject's legs, correctly positioned with respect to said indication on said platform via a detection system;

d. comparing signal obtained from first left-foot electromagnetic coil with signal obtained from first right-foot electromagnetic coil when the presence of a correctly positioned subject's legs have been positively detected on said platform for differences indicating presence of a metal object;

e. comparing signal obtained from secondary left-foot electromagnetic coils with signal obtained from primary left-foot electromagnetic coil to obtain an indication of mass and position of a metal object situated on left leg;

f. comparing signal obtained from secondary right-foot electromagnetic coils with signal obtained from primary right-foot electromagnetic coil to obtain an indication of mass and position of a metal object situated on right leg; and

g. displaying details of any suspected metal objects on said display.

9. A method of assembling a metal detecting facility for detecting metal objects attached to the lower leg of a subject; said method comprising the steps of:

a. enclosing a primary pair of horizontally aligned electromagnetic coils within a platform;

b. connecting said pair of horizontally aligned electromagnetic coils via an oscillator and a switch, to a processor such that current is supplied to each of said pair of horizontally aligned electromagnetic coils in turn;

c. indicating correct positioning of a subject's feet on upper surface of said platform;

d. attaching a foot detection means to said platform for detection of feet on upper surface of said platform, and connecting said foot detection means to said processor; and

e. coupling said processor to a display for indicating the detection of detected metal objects.

10. The method of claim 9 further comprising the step of attaching an electromagnetic damping screen in the vertical plane between said coils.

11. The method of claim 9 further comprising incorporating secondary pairs of electromagnetic coils aligned at an angle to said primary pairs of electromagnetic coils.

12. A method for detecting metal objects concealed in a shoe or on the lower part of a leg of a subject using a device as claimed in claim 2 , comprising the steps of:

a. applying current to a first left-foot electromagnetic coil, and a first right-foot electromagnetic coil in turn for a short time period that is typically several milliseconds and recording eddy current signals therefrom;

b. comparing signal from the first left-foot electromagnetic coil with signal from the first right-foot electromagnetic coil to eliminate effect of background interference;

c. positively detecting the presence of a subject's legs, correctly positioned with respect to said indication on said platform via a detection system;

d. comparing signal obtained from first left-foot electromagnetic coil with signal obtained from first right-foot electromagnetic coil when the presence of a correctly positioned subject's legs have been positively detected on said platform for differences; and

e. displaying presence of any differences on said display.

13. A method for detecting metal objects concealed in a shoe or on the lower part of a leg of a subject using a device as claimed in claim 3 , comprising the steps of:

a. applying current to a first left-foot electromagnetic coil, and a first right-foot electromagnetic coil in turn for a short time period that is typically several milliseconds and recording eddy current signals therefrom;

b. comparing signal from the first left-foot electromagnetic coil with signal from the first right-foot electromagnetic coil to eliminate effect of background interference;

c. positively detecting the presence of a subject's legs, correctly positioned with respect to said indication on said platform via a detection system;

d. comparing signal obtained from first left-foot electromagnetic coil with signal obtained from first right-foot electromagnetic coil when the presence of a correctly positioned subject's legs have been positively detected on said platform for differences; and

e. displaying presence of any differences on said display.

14. A method for detecting metal objects concealed in a shoe or on the lower part of a leg of a subject using a device as claimed in claim 4 , comprising the steps of:

a. applying current to a first left-foot electromagnetic coil, and a first right-foot electromagnetic coil in turn for a short time period that is typically several milliseconds and recording eddy current signals therefrom;

b. comparing signal from the first left-foot electromagnetic coil with signal from the first right-foot electromagnetic coil to eliminate effect of background interference;

c. positively detecting the presence of a subject's legs, correctly positioned with respect to said indication on said platform via a detection system;

d. comparing signal obtained from first left-foot electromagnetic coil with signal obtained from first right-foot electromagnetic coil when the presence of a correctly positioned subject's legs have been positively detected on said platform for differences; and

e. displaying presence of any differences on said display.

15. A method for detecting metal objects concealed in a shoe or on the lower part of a leg of a subject using a device as claimed in claim 5 , comprising the steps of:

a. applying current to a first left-foot electromagnetic coil, and a first right-foot electromagnetic coil in turn for a short time period that is typically several milliseconds and recording eddy current signals therefrom;

b. comparing signal from the first left-foot electromagnetic coil with signal from the first right-foot electromagnetic coil to eliminate effect of background interference;

c. positively detecting the presence of a subject's legs, correctly positioned with respect to said indication on said platform via a detection system;

d. comparing signal obtained from first left-foot electromagnetic coil with signal obtained from first right-foot electromagnetic coil when the presence of a correctly positioned subject's legs have been positively detected on said platform for differences; and

e. displaying presence of any differences on said display.

16. A method for detecting metal objects concealed in a shoe or on the lower part of a leg of a subject using a device as claimed in claim 6 , comprising the steps of:

a. applying current to a first left-foot electromagnetic coil, and a first right-foot electromagnetic coil in turn for a short time period that is typically several milliseconds and recording eddy current signals therefrom;

b. comparing signal from the first left-foot electromagnetic coil with signal from the first right-foot electromagnetic coil to eliminate effect of background interference;

c. positively detecting the presence of a subject's legs, correctly positioned with respect to said indication on said platform via a detection system;

d. comparing signal obtained from first left-foot electromagnetic coil with signal obtained from first right-foot electromagnetic coil when the presence of a correctly positioned subject's legs have been positively detected on said platform for differences; and

e. displaying presence of any differences on said display.