Ground piercing metal detector having range, bearing and metal-type discrimination
First Claim
1. An improved hand tool for detecting buried metal objects, the tool having a hand grip attached to a ground piercing probe which is manually insertable into soil to displace the soil radially outwardly from the probe, wherein the improvement comprises:
- (a) the probe having a chamber spaced from the hand grip for being positioned within the soil; and
(b) a metal detection circuit comprising;
(i) a signal generator connected to an inductor in the chamber and generating a time varying current through the inductor for inducing eddy currents in the buried object when the probe is inserted in the soil, (ii) a detector circuit connected to an inductor in the chamber for detecting current induced in the inductor by the eddy currents, and (iii) a signaling circuit connected to the detector circuit for signaling detection of current induced in the inductor connected to the detector circuit by the eddy currents.
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Accused Products
Abstract
A hand tool has a handgrip attached to a ground-piercing probe, which is manually insertable in the soil. The probe has a chamber in which at least one inductor is positioned and connected to metal detection circuitry. The preferred circuitry has a pulse generator applying current pulses to an inductor for inducing eddy currents in a buried target object. After the pulse terminates, the decaying coil voltage is sampled at different times to detect both the presence and range of the object, as well as the type of metal in the object. An asymmetric magnetic field pattern about the probe is aligned with a direction pointing indicium on the handgrip and provides directional sensitivity. The coil voltage samples are applied to signaling circuitry, which provides an audible signal which is a series of bursts of an audio tone. The pitch of the audio tone signals the presence, range and bearing of the buried metal object, while the pulse rate of the bursts signals the metal type.
35 Citations
33 Claims
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1. An improved hand tool for detecting buried metal objects, the tool having a hand grip attached to a ground piercing probe which is manually insertable into soil to displace the soil radially outwardly from the probe, wherein the improvement comprises:
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(a) the probe having a chamber spaced from the hand grip for being positioned within the soil; and
(b) a metal detection circuit comprising;
(i) a signal generator connected to an inductor in the chamber and generating a time varying current through the inductor for inducing eddy currents in the buried object when the probe is inserted in the soil, (ii) a detector circuit connected to an inductor in the chamber for detecting current induced in the inductor by the eddy currents, and (iii) a signaling circuit connected to the detector circuit for signaling detection of current induced in the inductor connected to the detector circuit by the eddy currents. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
(a) an inductance detector connected to the inductor for detecting a signal which varies as a function of changes in the apparent inductance of the inductor; and
(b) a signaling circuit connected to the inductance detector for signaling the direction and magnitude of change in the apparent inductance of the inductor as the probe is moved.
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Specification