White's Electronics, Inc.

Anne E Kelley

Carl Moreland

John W Plautz

Jeff Kelley

Robert M Canaday

Jeffrey L Kelley

Brian Hupy

A metal detector has a motion sensor such as an accelerometer to determine direction, speed, duration and acceleration of search loop motion. The search loop motion information from the motion sensor is utilized in mode selection, signal processing, target analysis, and information display.

Metal detector with motion sensing

Metal detectors use graphical displays offering many analysis methods and user options which were not possible before. The new graphical detector displays allow new ways to display target information that enable better methods of analyzing and viewing target data. Graphical detectors have menu structures with dozens of operating parameters which can be modified by the user. Some of these parameters are able to be changed on-the-fly without having to suspend detector operation.

Metal detector analysis and display methods

A metal detector for detecting objects that are composed of non-ferrous metals. The metal detector provides for a reduced rate of false positive responses to objects composed of ferrous metals. A preferred metal detector according to the invention includes a transmitter for transmitting a time-varying electromagnetic signal and a receiver for receiving a responsive time-varying electromagnetic signal produced by the metal object. The metal detector also includes an analyzer for determining the resistive and reactive components of the responsive signal as respective first and second functions of the spatial position of the detector. A module for determining and comparing rates of change of the first and second functions at one or more spatial positions is included. Preferably, when the rates of change are the first derivatives or slopes of the functions, and when these are of the same sign, a result indicating that the metal object is non-ferrous is provided by the module. A preferred method for identifying with an improved degree of reliability a non-ferrous metal object versus a ferrous object. The resistive and the reactive components of the responsive electromagnetic signal are determined as respective first and second functions of the spatial position of the detector, and the rates of change of the first and second functions at one or more spatial positions are compared. Preferably, if the rates of changes are the first derivatives or slopes of the functions, and these are of the same sign, a result that the object is non-ferrous is provided.

Detector for non-ferrous metals with reduced false positive responses

A metal detector having a plurality of phase delay discrimination regions with corresponding selectable exception spaces therein. A metal detector for indicating the presence of a metal target, comprising a transmitting module for transmitting a time-varying electromagnetic wave to the target, a receiving module for receiving said wave as modified by the target, an analyzing module for determining the phase delay of the modified said wave and providing a characterization to a user of the target based on said phase delay, said analyzing module being further adapted in a normal mode of operation of the metal detector to report said characterization to the user in a circumstance (a) wherein said phase delay exceeds a predetermined discrimination level and to not report said characterization to the user in a circumstance (b) wherein said phase delay does not exceed said discrimination level, and an exception space circuit cooperating with said analyzing module for comparing said phase delay with a limited range of one or more predetermined values for said phase delay and, in a first exception space mode of operation of the metal detector, causing said analyzing module to not report said characterization in said circumstance (a) when said range of values exceeds said discrimination level and, in a second exception space mode of operation of the metal detector, report said characterization in circumstance (b) wherein said range of values does not exceed said discrimination level, is provided.

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Corvallis, OR, United States of America

Anne E Kelley