Patent ID: 7265551
Filing Date: 2007-09-04
Classification: F41H,G01V

Abstract:
1. A metal detector for finding and locating metal objects located underneath a ground surface, comprising: a search head with a transmitting unit for transmitting electrical and/or magnetic signals or signal sequences past the surface; a metal detection unit with a receiving unit for response signals or response signal sequences, said receiving unit having at least one response signal strength sensor, and a device for indicating or displaying a presence of a metal object underneath the surface; a distance measurement sensor disposed on or in said search head and configured to estimate a depth and a size of the metal object and to determine an actual instantaneous geometric distance between said search head and the ground surface; a measurement data logic unit disposed to receive data from said response signal sensor and said distance measurement sensor, said measurement data logic unit receiving sets of response signal measurement data and ground distance measurement data, and generating a respective instantaneous distance/signal strength curve or algorithm reflecting a functionality between the response signal and the distance between said search head and the surface; a curve comparison unit connected for dataflow and data interchange with said measurement data logic unit, and a standard curve and algorithm storage unit connected for dataflow and data interchange with said curve comparison unit, said standard curve and algorithm storage unit containing a collection, matrix or library with a large number of standard distance/signal strength curves or algorithms, predetermined with a comparative detector of a same type from a large number of different, in each case predetermined standard conditions or with predetermined standard parameters, and being configured to be supplied therefrom with the standard distance/signal strength curves or algorithms, and equipped with software for selection of a standard distance/signal strength curve or algorithm stored in said standard curve and algorithm storage unit and most similar to the respective distance/signal strength curve or algorithm determined at that time for the metal object currently being located; and a categorization unit for emitting from said curve and algorithm comparison unit parameter information associated with the respective standard distance/signal strength curve or algorithm selected from said standard curve storage unit and which is most similar, said categorization unit converting the information to qualitative or semi-quantitative object depth data and object size data, to a display unit configured to display in a small number of discrete measurement value steps at least those values that correspond to the depth and the size of the respective currently located measurement object, at a point which is easily visible for a user of the metal detector.