Search Coils

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Metal detectors coil and search head design- Patents and Utility Models

Part 1

Beginning this historical review for

this how metal detectors searchcoils and search heads designs

are being developed year in,

year out, I understood that it is

almost impossible not only to be

included all Patents and Utility

Models in this abstract, but it is

also almost impossible to be

found everything which have

ever been published in the Patent

Offices in the World reach back

!o I understood that the difficulty

comes not only from the different

denominations of this unalterable

part of metaldetectors called ina different way by inventors and

producers " #coil$,#head$,

$antenna$,$sensor$,$loop$ "

but from that information about

their techni%ue characteristics,

© Copyright 2007 DeepTech Metal Detectors.All rights reserved.

Page 1

mailto:[email protected]

mailto:[email protected]





But, as 3arl Moreland mentiones in his article #3oil basics$ for

one of the kinds of search coils " #&lthough overlap coils

probably date back to the earliest e4periments involving induction

5 /6127s8, and were definitely in use in the early 92th

century$

&lso we should not forget that

&le4ander -raham Bell had

been e4perimenting with the

design of metal detector based

on a device to correct the

interference of induction on atelephone lineBell began to

construct a metal detector

based on an induction balance

invented by his friend :avid

;ughes

;ughes designed and built

the Induction Balance,a

device whose principle led

to the development of themine detector It was a loose

connection in this device that

led him to investigate what

became known as radio waves

)owards the end of /6<0 Dra!ings "y A.#.$ell% 2& '(ne%)**)

;ughes noticed that loose

connections in his induction

balance made them sub=ect to *sudden electrical impulses,

whether given out to the atmosphere through the e4tra current

from a coil or from a frictional machine*


Page 3



In /662 he demonstrated the e%uipment to members of the .oyal

!ociety(


Page 4



)hese men, although prominent in various scientific fields, did

not give it much importance -eorge !tokes dismissed it as simply

caused by induction ;ughes, somewhat disappointed, continuedto e4periment on the idea privately ;e did not publish his

research

!o, bit by bit the information

increased more and more and

I decided to stop here and

periodically fill this review in

with other published Patentsand Utility Models for metal

detectors search coils from

my archive and may be in the

future with short summaries

of the novelties and of the patent )he mine detector !3.">9?, used by

claims of their creators &nd the U! &rmy,/0@@

why not with photos of productscreated under this patents and

sold on the marketA

It would be pleasure for me if the people interested in this sub=ect,

independently from which part of the world they come from,

having information for published but not so well"known patents

and utility models, share it to enrich together this chronology

$y+,.#eorgieva

-ersion ).0 '(ne%2007

© Copyright 2007 DeepTech Metal Detectors.All rights reserved

Page 5



● 1930 – Dr.Richard Ambronn – Patent 494831

-er/ahren z(r eletrischen $odener/orsch(ng 1ittels de1 Unter

gr(nd ind(tiv z(ge/hrter 3echselstr41e (nd A(s1ess(ng des

elliptisch polarisierten 1agnetischen 5eldes d(rch 6(chsp(len.

erfahren +ur elektrischen Bodenerforschung mittels dem Untergrund induktiv +ugefChrter

WechselstrDme und &usmessung des elliptisch polarisierten magnetischen 'eldes durch !uchspulen

pen /(ll do(1ent+

● 1936 - Chare! "edden - Patent #$ 2129058

Trans/or1er /or a 1etal locator

Ob=ect of the invention resides in providing an improved metal locator of an electrical nature in

which the act of detection and location is controlled with great sensitivity by the use of balanced

induction coils

pen /(ll do(1ent+


Page 6

http://deeptech-bg.com/ambronn494831.pdf

http://www.freepatentsonline.com/2129058.pdf


http://deeptech-bg.com/ambronn494831.pdf





)he present invention relates to mine detectors and particularly to a novel search head and

method of manifacturing the same& typical search head of the type under consideration

comprises a #transmit$ and two #receive$ coils

pen /(ll do(1ent+

● 1969 - Robert Penand – Patent #$ 3549985

Metal detecting device having a disshaped head /or ho(sing a coil

syste1

An electronic detector device construction which comprises a molded head for coil housing having groovesmolded therein to receive electronic coils and having a hardered gel coating on the surface...

pen /(ll do(1ent+

● 19*2 - %iiam +ahan - Patent #$ 3*53185

Metal detecting search coil


Page 8







)he search coil is an induction coil enclosed within an annular chamber formed from a plastic

housing having the form of a spoked wheel for e4ample,and which is formed from two mating

housing halves)he coil is made up of a number of turns of insulated wire wherein the insulation

material

pen /(ll do(1ent+

● 19*3 - $herman Ander!on – Patent #$ 3823365

Metal detecting apparat(s haved i1proved gro(nde//ect i11(nity

& B'O metal detector includes a support for carrying a search coil and plural compensating

coils which prevent ground effects from changing the beat fre%uency output)he search coil forms

part of a tuned circuit

pen /(ll do(1ent+

● 19*4 – Aden +cDanie -Patent #$ 38823*4

Trans1iting,eceiving coil con/ig(ration


Page 9







& transmitting coil is located in the same plane as two receiving coils one of which is of greater

diameter than the receiving coil and the other of which is of smaller diameter

pen /(ll do(1ent+

● 19*4 - Robert )ardiner – Patent #$ 38*2380

Metal detector disting(ishing "et!een di//erent 1etals "y (sing a "ias

circ(it act(ated "y the phase shi/ts "y the 1etals

& metal detector is described utili+ing a transmitting and receiving coil for detecting the presence

of metal ob=ects positioned in the field of the coils

pen /(ll do(1ent+


Page 10







● 19*9 – ,riedric hom'!on - Patent #$ 4255*11

Coil arrange1ent /or search head o/ a 1etal detector

& unitary balanced"inductor system for use in the search head of an electronic metal

detector,having a transmit coil, a smaller, preferably concentric cancel coil of opposite polarity, and a yet smaller receive coil

pen /(ll doc(1ent+

● 19*9 - Caro! Ri/ero! – Patent #$ 42*6484

Method and apparat(s /or controlling c(rrent in ind(ctive loads

s(ch as a large dia1eter coils

& method and apparatus for controlling electric current in loads that are essentially

inductive

pen /(ll do(1ent+

● 19*9 – Do(ga! ohn!on – %hite! eectronic! nc.– Patent - #$ 4293816

$alanced search loop /or 1etal detector


Page 11









& search loop for a metal detector is described having a magnetic flu4 feedback coil whose

magnetic flu4 opposes that of the transpit coil to provide a balanced loop

pen /(ll do(1ent+

● 1980 – Pa( %i!on – Patent #$ 4345208

Anti/alsing and zero n(lling search head /or a 1etal detector

& metal detector search head which includes a transmitter wire coil and a receiver wire coil

each having first and second coil sections )he first coil sections of the receiver and

transmitter coils lie in substantially the same plane with the second coil sections thereof

being parallel

pen /(ll do(1ent+


Page 12








● 1984 – a(! binger – #tiit +ode )8336122.*

6(chsp(lenanordn(ng

:ie rfindung betrifft eine !uchspuleanordnung fCr einen Metalldetektor mit einem ringfDrmigen

-ehEuse mit einer umlaufenden Fut +ur &ufnahme der !pule, mit einem von aussen an das -ehEuse

angeset+ten und mit diesem verbundenen 'lansch +um elektrischen und mechanischen &nschluss

pen /(ll do(1ent+

● 1985 – Andre inard - Patent #$ 4552134

89(ip1ent /or deter1ining the position o/ a 1etal "ody in a 1edi(1

!ith lo! electric cond(ctivity


Page 13

http://deeptech-bg.com/ebinger8336122.7.pdf




)he e%uipment comprises a support,a radiating self"induction coil mounted on the support and two

receiving self"induction coils mounted on the support

pen /(ll do(1ent+

● 1985 – r(ce err - Patent #$ 4659989

:nd(ctively "alanced 1etal detector circ(it !ith orthogonal "alancing

signals and incl(ding phase and polarity detection

Metal detection apparatus includes an oscillator coil driven by an oscillator , which inducesin detector coils e%ual and opposite M's such that a nominally +ero output is produced at

terminals :

pen /(ll do(1ent+

● 198* – r(ce Cand - Patent #$ 4890064

Metal detector sensing head !ith red(ced eddy c(rrent coils


Page 14







& sensing head for a metal detector including means for magnetic transmission and

detection of a retransmitted signal from a target by means of at least one coil, the head

being characteri+ed in that at least some of the conductor material

pen /(ll do(1ent+

● 198* – a(! binger - Patent P 0249110

6earchcoil /or 1etal detector


Page 15





in als :ifferen+messer arbeitendes MetallsuchgerEt enthElt als wesentliche lemente einen

Os+ilator, eine an diesen angeschlossene !enderspule,mindestens +wei mpfEngerspulen

pen /(ll do(1ent in #er1an+

● 1988 – n/entor! 7rom %hite! ectronic! - Patent #$ 4862316

6tatic charge dissipating ho(sing /or 1etal detector search loop

asse1"ly


Page 16

http://www.freepatentsonline.com/EP0249110.pdf




& housing for the magnetic induction coils of the search loop assembly of a metal detector is

constructed of plastic resin reinforced with non"metallic electrically conductive graphite fibers, and

is connected to ground potential of the main electronics package of the metal detector so that the

housing acts as a static"draining shield for the search loop assembly

pen /(ll do(1ent+

● 1988 – aon )mb" – #tiit +ode )8811496.1

Metalls(chger;t 1it einer Detetorsonde


Page 1*





MetallsuchgerEte dieser -attung sind mit einem !tromer+euger verbunden und er+eugen mittels

ihrer im !ondengehEuse einliegenden 'eld" und mpfangspulen ein elektromagnetisches

Wechselfeld, wobei ein magnetisches Ortungssignal

pen /(ll do(1ent+

● 1990 – ohn $(tton - Patent #$ 5311198

Active antenna

&n antenna,which may be a search coil,is connected to an operational amplifier circuit which

provides negative impedances,each of which is in the order og magnitude of the positive

impedances which characteri+e the antenna

pen /(ll do(1ent+

● 1990 - n/entor! 7rom R(!!ia - #$ 5038106

Detector o/ 1etalli/ero(s o"<ects having t!o pairs o/ receiving loops sy11etrical and orthogonal to a driving loop


Page 18

http://deeptech-bg.com/vallon8811496.1.pdf



http://deeptech-bg.com/vallon8811496.1.pdf



)he detector of metalliferous ob=ects comptising an electrically coupled to an altenating voltage

generator driving loop,rigidly fitted to two pairs of receivingloops,positioned at opposite sides of

the driving loop,coa4ial and parallel to one another

pen /(ll do(1ent+

● 1992 – n!tit(t Dr.,riedrich ,or!ter – #$ 524530*

6earch coil asse1"ly /or electrically cond(ctive o"<ect detection

© Copyright 2007 DeepTech Metal Detectors.All rights reserved. Page 19






& search coil assembly for an inductive search device of the transmitterGreceiver type is described

having advantages relative to manufacture, repeat accuracy and sensitivity in operation

pen /(ll do(1ent+

● 1993 - a(! binger – #tiit +ode ) 9300*88.4

,ing/4r1ige 6onde /r ein Metalls(chger;t

.ingfDrmige !onde fCr ein MetallsuchgerEt, mit einer ;auptspule und mindestens +wei Febenspulen,mit einem .ingkDrper,der die ;auptspule aufnimmt

pen /(ll do(1ent+

● 1994 – aon )mb" – Patent P 06546851

8inricht(ngen (nd -er/ahren z(1 8rennen von Metallgegenst;nden








:ie vorliegende rfindung betrifft einen gepulsten Metalldetektor mit einer !onde fCr ein

MetallsuchgerEt mit mindestens einer !ende"und mpfangsspule und einer dafCr geeigneten

elektronischen

pen /(ll do(1ent+


Page 21





● 1995 – n!tit(t Dr.,riedrich ,or!ter – Patent D 441*931

6chalt(ngasanordn(ng z(r 3ahrneh1(ng (nd rt(ng von

Metallgegenst;nden

:ie rfindung betrifft eine !chaltungsanordnung +ur Wahrnehmung und Ortung von

MetallgegenstEnden, die sich in grDsserer )iefe unter dem rdboden oder an sonstigen der

unmittelbaren Beobachtung un+ugEanglichen !tellen befinden

pen /(ll do(1ent+

● 1996 – a(! binger -Patent P 0*64856

6onde /r ein Metalls(chger;t

6ensor /or a 1etal detector


http://deeptech-bg.com/foerster4417931.pdf

http://deeptech-bg.com/foerster4417931.pdf



:ie rfindung betrifft eine !onde fCr ein MetallsuchgerEt mit einem ringfDrmigen

!ondenkDrper,welcher erbindunsstege lEngs seiner Mittel" undHuerachse aufweist und

pen /(ll do(1ent+

● 1996 – n!tit(t Dr.,riedrich ,or!ter – D 4423661 A1

6(chsp(lenanordn(ng


Page 23





Bei einer !uchspulen &nordnung fCr ein inductives !uchgerEt mit mindestens

einer,erfordenlichenfalls mit mehreren +u lateral ausgehenden 'eldern kombinierbaren

!endespulen +ur r+eugung eines verEnderlichen Magnetfeldes

pen /(ll do(1ent+

● 1998 – n!tit(t Dr.,riedrich ,or!ter – D 19648833A1

-er/ahren (nd -orricht(ng z(r =oalisier(ng (nd :denti/izier(ng

von i1 $oden verstecten 6(cho"<eten% ins"esondere Plasti1inen


Page 24

http://deeptech-bg.com/foerster04423661A1.pdf

http://deeptech-bg.com/foerster04423661A1.pdf





● 2002 – +(!ta7a #man - Patent D 1015***0 C1

Metalls(chger;t

:ie rfindung betrifft ein MetallsuchgerEt mit +u mindest einer )reibeschaltung,+u mindest einer

+wei Eussere &nschlCsse aufweisenden !endewicklung und +umindest einer +wei Eusser

pen /(ll do(1ent+


Page 26

http://deeptech-bg.com/uzman10157770C1.pdf

http://deeptech-bg.com/uzman10157770C1.pdf





& pulse inductive metal detector that includes a variable resistor for controlling coil characteristics

for both transmitter and receiver modes of operation & coil coupled with an electronic switch is

charged with current from the power source in a transmitter mode

pen /(ll do(1ent+

● 2004 – r(ce Cand – Patent #$ 6690169

:nter/erence cancelling 1etal detector incl(ding electronic

selection o/ e//ective sensing coil arrange1ent


Page 28





Metal detection apparatus cotaining at least two inductive coils one of which acts as a transmit coil

and all of which act as receive coils and processing circuity wherein a proportion of the first

receive electronic signal and a proportion of the second receive electronic signal may be selected

to produce various first resultant linear combination signals for the purpose of improved

interference cancelling

pen /(ll do(1ent+

,e/erences+

1.htt';<<&&&.7ree'atent!onine.com<

2.htt';<</3.e!'acenet.com<

3.htt';<<d'ma.de<

4.htt';<<'atent!1.ic.gc.ca<intro-e.htm

5.htt';<<&&&.e(dem./(b.ac.be< 6.htt';<<&&&.(!'to.go/<


Page 29


http://www.freepatentsonline.com/

http://v3.espacenet.com/

http://dpma.de/

http://patents1.ic.gc.ca/intro-e.html

http://www.eudem.vub.ac.be/

http://www.uspto.gov/


http://www.freepatentsonline.com/

http://v3.espacenet.com/

http://dpma.de/

http://patents1.ic.gc.ca/intro-e.html

http://www.eudem.vub.ac.be/

http://www.uspto.gov/



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