Announcement

**Mustafa** · 05-08-2009, 10:27 AM

http://patft.uspto.gov/netahtml/PTO/search-adv.htm
Query: ttl/"object detector" and isd/1/1/1790->5/8/2009

1 7,518,491 Ultrasonic object detector
2 7,498,580 Tomographic device and method with translational movement between object and detector
3 7,423,739 Method of and system for determining the aberration of an imaging system test object and detector for use with the method
4 7,382,442 Object detector of vehicle
5 7,346,206 Optical object detector
6 7,260,253 Method for correction of relative object-detector motion between successive views
7 7,113,092 Ferromagnetic object detector
8 7,082,210 Moving object detector and image monitoring system
9 7,054,467 Information processing apparatus, information capturing apparatus, information integration apparatus, controller, object detector, and information processing method
10 7,026,978 Object detector and object detecting method
11 6,937,183 Object detecting method and object detector
12 D501,210 Display screen for an object detector
13 6,828,931 Process for adjusting the detecting axis of an object detector
14 6,498,333 Optical object detector with automatic sensitivity control
15 6,487,303 Object detector
16 6,408,051 Electromagnetic object detector provided with an additional electrode and intended for a medical radiation apparatus
17 6,396,433 Talking buried object detector
18 6,380,532 Optical object detector with multiple photodetectors
19 6,347,266 Automatic traveling vehicle with object detector
20 6,211,784 Object detector and object detector system
21 6,011,754 Personal object detector with enhanced stereo imaging capability
22 5,986,265 Infrared object detector
23 5,928,149 Electromagnetic object detector with test electrode for a medical diagnostic apparatus
24 5,883,935 Object detector and associated driving device for a medical diagnostic apparatus
25 5,877,706 Ferromagnetic object detector
26 5,828,221 Electromagnetic object detector for a medical diagnostic apparatus
27 5,724,313 Personal object detector
28 5,689,184 Large scale metallic object detector
29 5,637,040 Infrared object detector
30 5,634,846 Object detector for air conditioner
31 5,591,916 Foreign object detector for vehicles and other machinery
32 5,581,094 Photodetector, a photodector array comprising photodetectors, an object detector comprising the photodetecter array and an object detecting procedure
33 5,563,848 Object detector for detecting buried objects
34 5,543,917 Object detector
35 D368,137 Foreign object detector for human or other animal body
36 5,404,225 Object detector
37 5,354,983 Object detector utilizing a threshold detection distance and suppression means for detecting the presence of a motor vehicle
38 5,155,347 Object detector for an optical instrument
39 5,134,292 Moving object detector and moving object detecting system
40 5,019,822 Marine object detector
41 5,001,425 Ferromagnetic object detector with comparison of signal maximums from a pair of detection coils
42 4,868,499 Object detector with feedback which holds constant the product of the transmitter coil current and frequency to maintain constant sensor voltage output
43 4,719,604 Reflective object detector with compensated receiver signal
44 4,649,270 Photo-electric object detector having removable field stop means
45 4,596,006 Ultrasonic object detector
46 D282,350 Portable receiver unit for a metallic object detector
47 D282,246 Portable transmitter unit for a metallic object detector
48 4,512,000 Object detector which compares returned signals from successive transmissions
49 4,486,712 Frequency dependent pulsed gain modulated metallic object detector
50 4,459,561 Phase-lock loop controlled object detector oscillator

**Tinkerer** · 05-08-2009, 02:41 PM

Mustafa,

Thanks for the great job. This must have been a lot of work.

Tinkerer

**Mustafa** · 05-08-2009, 02:41 PM

Metal Detectors for Humanitarian Demining: a Patent Search and Analysis
http://www.eudem.vub.ac.be/publicati...DPatentSearch/

Metal Detectors: Patent Listing

1. Induction Balance
1.1 Single Frequency
1.1.1 Discrimination
1.1.2 Background Rejection
1.2 Multiple Frequency
1.2.1 Discrimination
1.2.2 Background Rejection
1.3 Others
2. Pulse Induction
2.1 Discrimination
2.2 Background Rejection
2.3 Others
3. Miscellaneous
3.1 Coil and Search Head Design
3.2 Electronics
3.3 Displays and Audio Feedback
3.4 Imaging
3.5 Cavity Detectors
3.6 Combined Systems
3.7 Arrays / Vehicles / Walk-Through Detectors
3.8 (Trip-)Wire Detection
3.9 Sinewave Damping Principle
3.10 Others
4. Others
4.1 Frequency Shift
4.2 Magnetometers and Magnetic Field Measurements
4.3 Other Geophysical
4.4 Miscellaneous
4.5 Other Mine Detection Systems

Full Final Report v2.0 (in PDF) Patents listed by publication date (in PDF) Patents listed by inventor (in PDF) Patents listed by assignee (in PDF)
NOTE: HTML files are ideal for browsing ( contain links to ALL the individual patents), PDF files for printing.

**Rov** · 05-08-2009, 04:05 PM

This needs a Topic in the Forums Itself for Reference/Links.Great Job!Mustafa.
Ive especialy bookmarked this Page/thread for my reference for later use.Fantastic!

**Mustafa** · 05-08-2009, 04:58 PM

Hi Rov,
I think there is no need for a seperate topic. Geotech already has one.
http://www.geotech1.com/cgi-bin/pages/common/index.pl?page=metdet&file=patents.dat
This thread is only for helping Carl to update his list.

**Rov** · 05-09-2009, 02:19 AM

Sorry ive overlooked that page link,only looked thru Schematics,an there above is patents! I better look past my nose next time!Thank You.

**aft_72005** · 05-09-2009, 06:19 AM

Let's compile a complete reference list for metal detector related patents.

Thank you

, Mustafa .
Best regards.

**Carl-NC** · 05-09-2009, 11:48 PM

Thanks, Mustafa... I need to update the patents on Geotech.

**Mustafa** · 04-02-2011, 08:15 PM

Query: ttl/"metal detector" and isd/5/8/2009->4/2/2011

Title: Balancing circuit for a metal detector
Document Type and Number: United States Patent 7893690
Abstract:
A balancing circuit for a metal detector. The metal detector includes an oscillating power source, a transmit coil connected to the oscillating power source, first and second receive coils inductively coupled to the transmit coil, a first amplitude balancing circuit connected to the first receive coil, and a first phase balancing circuit connected to the first receive coil. The first phase balancing circuit includes a capacitor and a variable resistor.
http://www.freepatentsonline.com/7893690.pdf

Metal detector for a milling machine
United States Patent 7828392
A milling machine for milling a paved surface having milling tools connected to an underside of a body of the machine and at least one metal detector attached to a front end of the machine. The metal detector has at least one electrically conductive coil disposed within a magnetically conductive, electrically insulating trough. Electronic equipment is in communication with the metal detector, the equipment being adapted to interpret feedback from the detector.
http://www.freepatentsonline.com/7828392.pdf

Metal detector
United States Patent 7816920
An exemplary metal detector includes a detecting circuit, a SCM, a converting circuit, and a cymometer. The SCM cooperates with the detecting circuit to generate a current signal with a specific frequency, the converting circuit transforms the current signal received from the SCM to a voltage signal, and the cymometer displays a value of a frequency of the current signal according to the voltage signal. When the detecting circuit detects a metal nearby, the value of the frequency of the current signal displayed on the cymometer changes.
http://www.freepatentsonline.com/7816920.pdf

Test device for metal detector portal structure
United States Patent 7793533
This invention relates to a test device for metal detector portal structure, characterized by the fact that it comprises a removable rack (10) comprising support and guide means (300) for displacement of a panel (400) capable of carrying a reference sample.
http://www.freepatentsonline.com/7793533.pdf

Rectangular-wave transmitting metal detector
United States Patent 7791345
A metal detector including transmit electronics having a plurality of switches for generating a repeating transmit signal cycle for transmission by a transmit coil. The repeating transmit signal cycle includes at least a high voltage period, and at least a low voltage period, the low voltage period followed by a substantially zero voltage period. The output impedance of the transmit electronics is less than three times the equivalent series resistance of the transmit coil during the low voltage period and the substantially zero voltage period.
http://www.freepatentsonline.com/7791345.pdf

Metal detector
United States Patent 7791337
A vibration canceling circuit for a metal detector. The metal detector includes a transmit coil, first and second receive coils, a differential circuit coupled to the first and second receive coils, a controller coupled to the differential circuit, and a vibration canceling circuit coupled to the controller. The controller uses a signal provided by the vibration canceling circuit to remove a vibration component from a metal detection signal.
http://www.freepatentsonline.com/7791337.pdf

Metal detector for an asphalt milling machine
United States Patent 7717521
A milling machine for milling a paved surface has milling tools connected to an underside of a body of the machine. At least one ferrous metal detector is attached to a front end of the machine. Electronic equipment is disposed within the machine and is in communication with the metal detector, the equipment being adapted to interpret feedback from the detector.
http://www.freepatentsonline.com/7717521.pdf

Resonant pulse induction metal detector that transmits energy from high voltage flyback pulses
United States Patent 7710118
A metal detector transmitting high current pulses and employing the high voltage back EMF signals which occur at their termination. The method employed uses a resonant tuned receive coil which provides a major improvement in the depth of detection of metallic objects and interference rejection over current time and frequency domain metal detectors.
http://www.freepatentsonline.com/7710118.pdf

Metal detector with magnet
United States Patent D614981
http://www.freepatentsonline.com/D614981.pdf

Metal detector with ball magnet
United States Patent D614980
http://www.freepatentsonline.com/D614980.pdf

Hybrid-technology metal detector
United States Patent 7701337
A hybrid-technology metal detector, using pulse-induction and sine-wave excitation of the transmitter coil alternately, in rapid succession.
The energy stored in the transmitter coil, in the pulsed mode, is used to shock-excite a high-Q circuit formed by the coil and a parallel capacitor into oscillations in the sine-wave mode.
The multiplicative action of the circuit Q causes high currents to flow in the transmitter coil, causing high fluxes to be impressed on the searched area, with increased sensitivity as a result.
Using a linear coil-current ramp to assess and minimize the coupling between the transmitter and receiver coils permits effective separation of the reactive and resistive components of the target signals, making accurate identification of targets possible.
http://www.freepatentsonline.com/7701337.pdf

Metal detector with reliable identification of ferrous and non-ferrous metals in soils with varying mineral content
United States Patent 7701204
A pulse-induction type metal detector that reliably identifies ferrous and non-ferrous targets in soils with varying mineral content. The influence of the background signals from the soil is removed continuously, without the need for manual adjustment of controls by the operator, when the soil mineralization changes. The background signals are removed without affecting the sensitivity of the detector to metallic targets and the background signal removal process does not make the detector insensitive to targets whose time constant coincides with that of the soil.
http://www.freepatentsonline.com/7701204.pdf

Metal detector with improved receiver coil
United States Patent 7656153
A pulse-induction-type metal detector in which the receiver coil comprises bifilar windings that are connected in series, opposing during the coil pulse and in series, aiding, following the coil pulse. Pick-up of energy by the receiver coil during the coil pulse is thereby minimized and the duration of oscillations is curtailed. Owing to the rapid recovery of the system from the flux change that is used to charge the target, the signal sampling gate can be positioned very close to the trailing edge of the coil-current pulse, whereby detection of targets with very short time constants is made possible.
http://www.freepatentsonline.com/7656153.pdf

Multi-frequency metal detector having constant reactive transmit voltage applied to a transmit coil
United States Patent 7652477
An electronic metal detector having a transmit coil (1) adapted to transmit an alternating magnetic field associated with a reactive transmit voltage, wherein the transmit voltage signal is selected such that the reactive transmit voltage is approximately constant for at least a time period during which a magnetic field signal to be processed is received by the detector for processing.
http://www.freepatentsonline.com/7652477.pdf

Pulse induction metal detector having high energy efficiency and sensitivity
United States Patent 7649356
A pulse induction metal detector having high efficiency and sensitivity. Within the scope of the invention is a high efficiency hand-held metal detector for detecting a metal object, comprising a coil and a source of current flow in the coil. The source is adapted to produce one or more pulses of current in the coil. Preferably, at least two of the pulses are spaced apart in time at least about 20 microseconds during which current flow in the coil is substantially constant. The metal detector also comprises a detecting circuit for detecting a response to the current pulses, and a sampling circuit for sampling the response at predetermined times at least during the time of one of the pulses.
http://www.freepatentsonline.com/7649356.pdf

Metal detector
United States Patent D605956
http://www.freepatentsonline.com/D605956.pdf

Metal detector presenting high performance
United States Patent 7592907
A metal detector for control of protected access comprises two oblong shape vertical housings (10, 12), a structure (14) connecting the upper part of the vertical housings (10, 12) and emitting and receiving electrical coils (3, 5) provided in the housings (10, 12). Each of the two housings (10, 12) comprises two separate emitting (3) and/or receiving (5) coils. The coils operate so that each of the two housings (10, 12) comprises one emitting coil (TX) and one receiving coil (RX). The metal detector further comprises a controller for controlling operation of the emitting and receiving coils, so that when an emitting coil (TX1, TX2) provided in a housing (10, 12) is active, the two receiving coils (RX1, RX2) provided respectively in both the two housings are also simultaneously or subsequently active.
http://www.freepatentsonline.com/7592907.pdf

Metal detector
United States Patent 7579839
A real time electronic metal detector including a magnetic transmitter (1) and a receiver (3), wherein the receiver includes approximate sine-wave weighted synchronous demodulation and a switched voltage signal is applied to the magnetic transmitter and the said receiver approximate sine-wave weighted synchronous demodulation is selected to receive synchronously with the switched voltage signal, such that the switched voltage signal and the receiver approximate sine-wave weighted synchronous demodulation may be altered by means of operator selection.
http://www.freepatentsonline.com/7579839.pdf

Metal detector with excavation tool
United States Patent 7575065
A hand-held metal detector and soil excavation device useful for locating and retrieving metallic objects concealed in soil or other materials. The device includes a housing with a hand-grip portion and an elongated probe portion. There is an excavation tool connected to the housing that is useful for moving soil to locate metallic objects that are sought. The device also includes a metal detector circuit located within the housing, that operates to generate an alert signal when the probe portion is moved into proximity of metallic objects.
http://www.freepatentsonline.com/7575065.pdf

Water resistant metal detector
United States Patent D593427
http://www.freepatentsonline.com/D593427.pdf

Metal detector
United States Patent D592981
http://www.freepatentsonline.com/D592981.pdf

Apparatus and method for automatic product effect compensation in radio frequency metal detectors
United States Patent Application 20110074401
A metal detector (40) used for identifying contaminants in packages (49, 50, 51) introduced into the metal detector by a conveyor. The detector (40) includes coils (1), a search head (2) and an analog to digital converter (3) that generates a reactive signal (13) and a resistive signal (14) in response to the presence of a contaminant in the region of the coils. A high pass filter (4) receives the reactive and resistive signals (13, 14). During a learning mode a sample product is introduced into the metal detector (40) to provide a representative product effect signal which is stored by the reactive learn memory (19) and the resistive learn memory (2

. The learn memory values (29, 32) are forwarded to reference processors (20, 35) to provide a reference value which is subtracted from each product signal during a normal production cycle, thereby canceling the product effect caused by each individual package as it passes through the metal detector. The long term product effect is monitored during successive cycles (54, 62) composed of a series of packages undergoing normal inspection by the metal detector (40). A tracking processor (4

averages the product effect signal (57, 58, 59) produced by the individual packages (49, 50, 51) and continuously produces and updates a product effect trend signal (60) to be used by the reference processors as the signal to be subtracted from each product signal.
http://www.freepatentsonline.com/20110074401.pdf

CONTINUOUS WAVE METAL DETECTOR
United States Patent Application 20110068795
A training set including a target object set and a clutter object set is accessed. It is determined that the training set includes multiple types of targets or multiple types of clutter. The target feature value of a type of target is compared with the clutter feature value. The type of target is associated with the non-target object based on the comparison. A classifier is trained using the target feature value and the clutter feature value of the associated type of target and the non-clutter object. A feature value associated with an unknown object is applied to multiple classifiers to generate a set of metrics for the unknown object. The metrics are aggregated into an overall metric. Whether the unknown object is included in the target set is determined based on the overall metric.
http://www.freepatentsonline.com/20110068795.pdf

METAL DETECTOR
United States Patent Application 20100315080
A metal detector is disclosed which comprises a transmitter arranged to generate a primary magnetic field, and at least one sensor arranged so as to sense a secondary magnetic field vector present after the transmitter has been turned off by measuring 3 substantially mutually orthogonal components of the secondary magnetic field. Each sensor is of a type arranged to sense a time-varying magnetic field.
http://www.freepatentsonline.com/20100315080.pdf

APPARATUS AND METHOD FOR CALIBRATING A TRAMP METAL DETECTOR
United States Patent Application 20100315068
An apparatus for calibrating a metal detecting device of a materials processing line. A placement arm is provided to control the path of a calibrating sample in order to simulate movement of tramp metal moving on a processing line along with materials being processed. Upper and lower arms of the placement arm are joined by an adjustable elbow which can be set to a maximum angle of extension in order to accurately place the calibrating sample at a preferred location in a detecting field of the metal detecting device.
http://www.freepatentsonline.com/20100315068.pdf

METAL DETECTOR WITH IMPROVED MAGNETIC RESPONSE APPLICATION
United States Patent Application 20100283467
This invention discloses a low cost metal detector which suppresses signals arising from signals induced in a receive inductor from a rate of change of environmental static fields. The metal detector processes a signal due to a rate of change of environmental static fields to produce a first signal, and processes a signal due to the transmitted magnetic field to produce a second signal, the second signal includes a proportion of the first signal. Signal processing includes the subtraction of an estimation of the proportion of the first signal from the second signal to produce a third signal, such that the third signal is substantially independent of the first signal; and the receive electronics further processes the third signal to produce an indicator output signal, the indicator output signal includes a signal indicative of the presence of a metallic target and is substantially unaffected by the signal due to a rate of change of environmental static fields.
http://www.freepatentsonline.com/20100283467.pdf

METAL DETECTOR FOR SALT SOILS
United States Patent Application 20100148960
This invention relates to metal detectors used to detect metal targets in soils wherein the detector is insensitive to signals induced by a received magnetic field due to perpendicular components of a uniform conducting half-space, including metal detectors simultaneously capable of suppressing signals due to components of substantially log-uniform viscous superparamagnetic soil, and including metal detectors using repeating transmit signal cycles resembling a pulse induction-like waveforms. It discloses signal processing, in particular synchronous demodulation functions which may simultaneously substantially suppress signals due to perpendicular components of a uniform conducting half-space in a received magnetic field, signals due to components of substantially log-uniform viscous superparamagnetic soil, and signals due to a movement of the receive coil with respect to a static magnetic field.
http://www.freepatentsonline.com/20100148960.pdf

RECTANGULAR-WAVE TRANSMITTING METAL DETECTOR
United States Patent Application 20100148781
A metal detector including transmit electronics having a plurality of switches for generating a repeating transmit signal cycle for transmission by a transmit coil. The repeating transmit signal cycle includes at least a high voltage period, and at least a low voltage period, the low voltage period followed by a substantially zero voltage period. The output impedance of the transmit electronics is less than three times the equivalent series resistance of the transmit coil during the low voltage period and the substantially zero voltage period.
http://www.freepatentsonline.com/20100148781.pdf

Speed filter calibration apparatus and method for radio frequency metal detectors
United States Patent Application 20100148761
A metal detector (40) used for identifying contaminants in products (23) introduced into the metal detector by a conveyor. The detector (40) includes coils (1), a search head (2) and an analog to digital converter (3) that generates a reactive signal (13) in response to the presence of a contaminant in the region of the coils. A calculation processor (32 ) receives the reactive signal (13) along with the value of the conveyor speed (9) to determine a calibration ratio R that is unique to each individual metal detector (40). The optimum frequency F for metal detector operation is equal to the conveyor speed (9) divided by the ratio R. The ratio R simplifies the selection of filter parameters (4,

for a speed filter (30) which correlates the conveyor speed (9) with the frequency F so as to deliver an optimized signal to the detection algorithm (10) used to determine the presence of a contaminant based on the signal (13) derived from the coils (1).
http://www.freepatentsonline.com/20100148761.pdf

CONSTANT CURRENT METAL DETECTOR WITH DRIVEN TRANSMIT COIL
United States Patent Application 20100141247
A metal detector transmitting, through a transmit coil, a repeating transmit signal cycle, which includes at least one receive period and at least one non-zero transmit coil reactive voltage period; and sensing a current in the transmit coil during at least one receive period to control a magnitude and/or duration of the at least one non-zero transmit coil reactive voltage period such that the average value of the current during at least one receive period of every repeating transmit signal cycle is substantially constant, and the current during at least one receive period is substantially independent of the inductance of the transmit coil.
http://www.freepatentsonline.com/20100141247.pdf

METAL DETECTOR WITH IMPROVED MAGNETIC SOIL RESPONSE CANCELLATION
United States Patent Application 20100026485
A metal detector with improved magnetic soil response cancellation is disclosed. The metal detector including, in one aspect, at least one or more inductors arranged and adapted to transmit and receive an alternating magnetic field, transmit electronics arranged and adapted to generate a transmit signal applied to at least one inductor to produce a transmitted magnetic field, at least one inductor, a first inductor, arranged and adapted to receive a magnetic field to produce a receive emf signal, the said first inductor being connected to receive electronics arranged and adapted to amplify and may filter the receive emf signal to produce a receive signal, the transmit signal is arranged and adapted to contain at least three different frequency components, a relatively high frequency component, a relatively low frequency component and a relatively medium frequency component, the receive electronics is arranged and adapted to contain signal processing which may process the receive signal to produce and output indicator signal, such that at least part of the signal processing includes at least one linear combination of in effect adding receive signal components containing at least relatively high frequency resistive components to receive signal components containing at least relatively low frequency resistive components and the resultant sum is subtracted from receive signal components containing at least relatively medium frequency resistive components to give a linear combination output, coefficients of the linear combination being selected so that a further processed linear combination output which may include filtering is approximately independent of signals from magnetic soils including at least some higher order effects of different soils under the influence of the transmitted magnetic field which may include small variations in a ratio of received relatively high frequency resistive components compared to medium frequency resistive components, and also may include small variations in a ratio of received relatively medium frequency resistive components compared to lower frequency resistive components, the said linear combination arranged and adapted such that the further processed linear combination output is responsive to at least some metal targets, and the further linear combination output is arranged and adapted to produce the said output indicator signal.
http://www.freepatentsonline.com/20100026485.pdf

METAL DETECTOR HAVING CONSTANT REACTIVE TRANSMIT VOLTAGE APPLIED TO A TRANSMIT COIL
United States Patent Application 20100019769
An electronic metal detector having, a transmit coil arranged and adapted to transmit an alternating magnetic field associated with a reactive transmit coil voltage, the transmit coil being connected to transmit electronics arranged and adapted to generate a transmit signal, the transmit electronics having at least two power sources, a first power source and a second power source, wherein the first power source is adapted and arranged to connect to the transmit coil for at least a first period, and the second power source is adapted and arranged to connect to tie transmit coil for at least a second period, the said transmit electronics including at least one servo control negative feedback loop, a first servo control negative feedback loop, which is adapted and arranged to monitor a transmit coil current for at least part of the said first period, and to control at least part of the said transmit signal, the transmit electronics being adapted and arranged to control the transmit signal to produce the reactive transmit coil voltage to be approximately constant and approximately equal to zero whilst the transmit coil current is non-zero and approximately constant for at least part of the first period; and receive electronics which are adapted and arranged to receive and process a receive magnetic field during at least some of the first period to produce an indicator output.
http://www.freepatentsonline.com/20100019769.pdf

MULTI-FREQUENCY TRANSMITTER FOR A METAL DETECTOR
United States Patent Application 20090318098
A method for generating a transmit signal for transmission including the steps of a) generating at least two selected rectangular wave signals, each having a different fundamental frequency; b) mixing the selected rectangular wave signals to produce a driving signal; and c) driving a switching circuit using the driving signal for generating a transmit signal for transmission, wherein the Fourier transform of the transmit signal contains frequency components of relatively high magnitude, at frequencies corresponding to the convolution of the fundamental frequencies of the said at least two selected rectangular wave signals, as compared to other frequency components across the frequency spectrum of the Fourier transform, and wherein the rectangular wave signals are selected such that the frequency components of relatively high magnitude are substantially the same in magnitude, and spaced from each other in the frequency spectrum in a predetermined manner.
http://www.freepatentsonline.com/20090318098.pdf

REAL-TIME RECTANGULAR-WAVE TRANSMITTING METAL DETECTOR PLATFORM WITH USER SELECTABLE TRANSMISSION AND RECEPTION PROPERTIES
United States Patent Application 20090315707
A highly flexible real-time metal detector platform which has a detection capability for different targets and applications, where the operator is able to alter synchronous demodulation multiplication functions to select different types or mixtures of different types to be applied to different synchronous demodulators, and also different waveforms of the said synchronous demodulation multiplication functions; examples of the different types being time-domain, square-wave, sine-wave or receive signal weighted synchronous demodulation multiplication functions. The operator can alter the fundamental frequency of the repeating switched rectangular-wave voltage sequence, and an operator may alter the waveform of the repeating switched rectangular-wave voltage sequence and corresponding synchronous demodulation multiplication functions.
http://www.freepatentsonline.com/20090315707.pdf

METAL DETECTOR
United States Patent Application 20090251138
An exemplary metal detector includes a detecting circuit, a SCM, a converting circuit, and a cymometer. The SCM cooperates with the detecting circuit to generate a current signal with a specific frequency, the converting circuit transforms the current signal received from the SCM to a voltage signal, and the cymometer displays a value of a frequency of the current signal according to the voltage signal. When the detecting circuit detects a metal nearby, the value of the frequency of the current signal displayed on the cymometer changes.
http://www.freepatentsonline.com/20090251138.pdf

Stealth Detector Metal Detector
United States Patent Application 20090231144
A portable metal detection system that includes a hand/wrist mounted metal detector with two search coils mounted on the palm side of the detector. The mounted metal detector includes a wireless transmitter and a small rechargeable fuel cell. The detection system also includes a separate housing that contains a wireless receiver, a small rechargeable fuel cell and an adjustable vibration or audio alert circuitry. The separate housing may be worn anywhere on the operator of the system. Once the hand/wrist mounted metal detector detects a metal object, the wireless transmitter sends a signal to the wireless receiver in the separate housing that activates the vibration or audio alert circuitry. The separation of the detection device and the alert circuitry prevents a metal detection detainee from hearing or feeling a metal detection alert.
http://www.freepatentsonline.com/20090231144.pdf

CONSTANT CURRENT METAL DETECTOR WITH DRIVEN TRANSMIT COIL
European Patent Application EP2291685
http://www.freepatentsonline.com/EP2291685A1.pdf

RECTANGULAR-WAVE TRANSMITTING METAL DETECTOR
European Patent Application EP2288942
http://www.freepatentsonline.com/EP2288942A1.pdf

Test device for walk-through metal detector
European Patent EP1744183
http://www.freepatentsonline.com/EP1744183B1.pdf

Cordless portable metal detector
European Patent EP1990658
http://www.freepatentsonline.com/EP1990658B1.pdf

WO/2011/035032A1 CONTINUOUS WAVE METAL DETECTOR
WO/2011/011820A1 IMPROVED METAL DETECTOR TARGET DISCRIMINATION IN MINERALIZED SOILS
WO/2010/147679A1 APPARATUS AND METHOD FOR CALIBRATING A TRAMP METAL DETECTOR
WO/2010/133328A1 METAL DETECTOR
WO/2010/079836A1 SENSOR COIL FOR METAL DETECTOR AND METAL DETECTOR
WO/2009/155668A1 CONSTANT CURRENT METAL DETECTOR WITH DRIVEN TRANSMIT COIL
WO/2009/155648A1 RECTANGULAR-WAVE TRANSMITTING METAL DETECTOR
WO/2009/113078A3 MULTIZONE WALK THROUGH METAL DETECTOR WITH CAMERA & TEXT OVERLAY
WO/2009/113078A2 MULTIZONE WALK THROUGH METAL DETECTOR WITH CAMERA & TEXT OVERLAY
WO/2009/062230A1 METAL DETECTOR WITH IMPROVED MAGNETIC RESPONSE APPLICATION

Announcement

Metal Detector Patents

Metal Detector Patents

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment