CA2431876A1 - Inductive sensory apparatus - Google Patents

Abstract

An inductive sensory system generally comprises a sense inductor, a reference sense inductor, an oscillator, a feedback control loop, and a comparator. The oscillator is connectable to both the sense inductor and the reference, sense inductor. Upon the oscillator being connected to the reference sense inductor, the feedback control loop establishes a fixed reference level. Upon the sense inductor being connected to the oscillator, the comparator compares the state of the sense inductor against a threshold that is derived from the fixed reference level to determine the change in inductance of the sense inductor.

Description

A,ttomCy Docket No. 2fi11.D~'S~001 -l IN1D'U~ SEl'~TSt~RY APPA1~'fllS
FIELD d~' THE TNVI;N'TIt~N
'Fhe present invcn'tsoa relates to inductive sensors and, more pazticuIarly, to an intFuctive ser~.so~r that determines the identity and nasitiou of a conductive pattern, ox object, in. praxirroty to t'~e sensor,- and that is additionally subska~xtially temp':rature and caxz~ponent toleraucc andepend~nt_ ~ACYGl~(~UND OF THE.'CiW~NTION
1t1 A sensor that determines the identity and. position, t~F a conttuctirra pattern. or abject is generally known as a "preseu~ sensor'°. Most presEnce se~t~z~s ease seed switcT~es and magnets to track the ruction of magnetic elements. These cler~ices usually have one reed swig placed Binder a plurality of discrete positions on the ser~.sor. When ~ ob,~act with a ,et .integrated therein is placad is a garti~aF ppSition, the reed switch is activated at~,d remains closed until the r~lr~ect is reznove~. In this tvaf, the positiotx of the objects p3aaed an the scx~sor zaay be determined and. tracked.
E~owever, sub devices catmot determine the identities of the abjecta placed ixgan the . surface of the sen_ror. only when speeii~c, predefined objects axe placed in predefaned positions on the sensory sur#'ace can. sacb devices detern~iz~e the identities of the objects placed upon the Zfl censor. Futelxeimore, suc$ devices ~az'e oiften inaceorate if the obj ec'ts are moved quickly, ac if two objects occupy the same position on a sensary~ su~Face. ' Iu moving away from a standard reed sv~ritchletic elennent presezxce sensor, pretence seasars u#g, a change irx the sadtictaace tit' sea~e oohs to indicate 'the location andlvr ddentity ~o~' an object have been d~eveloped_ Such a presence sensas gay be found an 't7.S. Pad~n't No.
~,T9 t,b48 thereat, the '64-S psteat), wl~tioh is entitled "~ndu,~ve Sensory Apparatus" a~ad is hereb3r xacorpotated toy isferetiae. The itlduciiwe sensory apparatus of tl~e i~48 patent ~.t;7;~~:c ~

,t~ttorney Docket Na. ~~11 _02WC101 a~_ matrix of eoals embedded in the surface of the agpaxatus. .t1. rcultiglcxor selects the individual coils bra ca~w.~cting them sequentially tt~ a~n >rC oscillator wrllere tE~ey act as the uuiucturs in the osea.Ilator circuit, Cbarrges in the inductance of nay coil results in correspoxrding chac~es in the amglitude and the frequency of oscillation of tlae oscillator~cir~it. ?he asciilatzoz~ amplitude of each coil is compared against at Ieast ~e voltage threshold by ann amplitude cortaparatoo The au~rlitutle ccymparator is sampled by 2~ rnirrocor~troller to detect the andu~ctaace of each coil. 'xhe raxicracontroller then assigns a value to each coil that is doted by the inductance of the coil.
$~r a~si~ing a value to each iaadividnral coilp the rnacroeomroller determines the Bade That ut~icluely idenfifiies the o~ect placed next to t1~ inductive sea..>ror apparatus.
1 U ~ While the inductive staasory apparatus of the '64S paie~xt is a significant imprave~rterrt over a standard need switthltnagnetic element presence sensor, it lies its ove~a limitatioes.
Spcally, the LC oscill~at~ar of the ir~ductiva sensory apparattus, which is used to detect clsanges in the self induetaace of the sensory coils near a. conductive pattam, is subject to amplitude and ~~ueaoy ~t~ariatians due to changes yn tempexxture and.
cornpoiient tolerances.
I5 1'ltis restiIts i~ra a. shill in the ~,'aiesccnt operating amplitude of the oscillator. Tlte shift in the quiescent oprxating amplitude lim.9ts the ability of the xndu~ctivv sensory aPPaus to detect small variations ix~ amplitude, caused by the proximity arf corxctuctive material to the inductive sensory apparatus.
Sdll an,Qther limitation of the i~acluctive sery aPparof the '648 patent as that a~
20 detects only the presettaa or absenee of eor~duative material in close proximity to each of the sense coils, which Iipuits the number of ohjeots'tbe~a'iw. ~ ~...d ~.,;;W ~
~vGn number of sense coils, due to the 'rise of binary ceded condur~ive patterns_ Yet ar~of~a Iirnitation of tl~e inductive sensory apPasafiys of the '648 patent is fihat while yt can detect the presence or disozcke location of.
'a conductive objrct; it dot detect the exact position os displacement ~of such an object;
25 . In view of the abovey there,i~ a need for an electronic, inductive sensory app~catus thax incotpoi~ubes unproved serzs~vity ~to daCect objects encoded with a conductive natty, nr *.~

,At~~ey Docl~et ~~. 26a a.ozwool _~,.
' detect the presence or lcrcativn of a conductive abjc~t at greater sensing distances for a given. coil size. Further, there is a reed for an electronic inducti'~e s~:xasoty apparatus that leas improved toierance and stability by automatically cot~pertsatxn~ for ~iatinzas in ~te~tpeaature and.
coa3.panent tolerances. ~urfller still, there is a need fos an elecfruztic inductive sensory app~atus that can dotact ate increased number o~ objects writh, a, given nunnber of sense coils, thmugh the detection of multiple conductive dates. There is also a nrxd, for an elec#tanic ~ductive sensory apparaters that can detect tha positiotl or displacement of an object StI~'h~l,RY OF T~iE 1N~E~'f~~7V
Th$ rrGeds clescribcd above sse irs Iarge measure ~nct by the indexctiwe, sensory system of thre present invention. The incluative sensory system generally comprises a sel~sc induc~r, a reference sense indutetor, an oscillator, x feed~bacl~; caxttxol lvvgy and a compasator The oscillator is cannectabla to both the sense anductor and the ref,~r~ce sense. inducfior.
Upon tii~ oscillator ~bein~g connea~ted m the reference ..oszse inductor, the ,feedback ronttol Iaop .establzshes a fixed.
~ 5 reference level. Upon the setrse xlnductor being corrneeted to the oscillator, the aomgar3tor c~ampares : fhe state ~of the setsse inductor against a threshold that i5 derived fro3m the' d reference level !cc detemrine ttie Ghaage in induce of the sense iudu~:tor.
The indrx~ctive sensory system further ittcltules a processor that selects between the sense inductor 2m~ the ref,'errencce sense induct~ar. The feedback cxatrol Iaop xnaiateins the faced refea~xcae Ievel substantially izrdependently of ambient temperature vmiatio~ns, supply wQltnge variations, and component taIerartee variations. The sea::e induce may be of v~ious cex~ftgttrataons including a flab romd or sqv~,xe sere coil and a triar~gulady-shaped or rectangularly-shaped sew coil. Tare sense iudtxaoas may Tae i~acorparated into x g'amebraard, doll or book, or a template positioned ~ a boole, to deteett inductive spats within pages o~ the book.

sA.ttotney 170cket No. Z611.U,2.'9J'(?U 1 The inductive sensory system xnay be configured fax cletectioa~ of multiple conductive states. In doing so, the re~rence level estabE9staed by 'the feedback conttot loop is ~.,~ed to deriYe at least t~vo tlaesholtls for comparison. ~e different thresholds a.]!ow for detection of dafferant conductive level$ in an object. Tltasa different conductive levels may be detected by the system regardless of the orientation of the object at a g~ivex~. sensing distance.
TJhe objeets are preferably encoded v,~th a printed pattern ox different materials $zst have dafferr~nt cbnchxctivities.
Specifically, the ihductivs sensory system may be used to detect trinaa~r patterns Qf objects encoded with t~xee distinct conductive sues, e.g. covvredy uncovered, partially cowered wit~t Go7~ductive tC~ElaI.
1U 'the indx~etive sc~ery system may employ triangextar or rectxrzgular shaped coils xo create a positioxi sensor that may be ia~corparated iota as attemmto~r or slide coatraller. r~ ~c~r~ductzve rnatetial is moved clang tl~e poi! axis a voltage is generated that as linearly proportiontat to the displacement of the conductive object. Tfzis voltage or its digital repre.ser~tation may be r~sect to control a rrariety of mechanical dovioes, audio volume, terr~p~r~a~e, .
$R~~F' DESCl~P'T~t~l~ C1F THE D:EiAWINCxS
Fig.1 is a block di$g~ram ofthe anduGtive seetsory appau~att~s ofthe pxes~t invention,.
Fig. 2 is a deta~etl eleetxonac circuit diag~ca~rt imple~ppteating the induatire serysory aPP~tus of l~ig. 1.
~ig_ 3 diagrams a brook with ooil templaie, showring offset co~d'uctive spats used for page detection.
Fig. ~ depicts tlYa oot~ixuction of a triangular-shaped sense coi! that may be utzlized with the anductivc sensory apparatus of the present inyentioa to detest tiae displaaexnent off' a ooncluc~ive object_ ~5 lEig. 5 SlaOv~ the con~on of a sealed conductive attennuatc~r.

,~ttomey Docket No. ~6t 1.02iJtr001 _5_ I3IrTAI~.ED 'D~~CR'C~'f~02~T OF THE i~R:EFERktirD E~IB~DD~'Z'~
T?ze inductive sensory apparatus of ~e present mve~i.on provides for increased sensitivity ailowing ii to detect objects encvcled witb a conductive patte~nn at greater segsirX,g dastanrxs, pe4vides for ent~a~.red tolesa~ncs and stability 'by autoanz~tically Gaxxapensating for variations is temperatcue and. Gbn~ponent tolerances, and prs~victes for an increase in the number of candac~ive objects detectable through detection of xz~ultipte coad~a~aive states.
I. Inductive Sensaly Apparatus Rcfertit~g tp ~ digs. 1 and 2, imd,active s~eaxy apparatus I O of the present itrveation is 1U depicted. A,s showy inductive sensory apparatus 10 generally iixalr~des a pluraxi.~ty of coils ~D, each of whicJ~ farms part t,f an LC oscillate; 22 and each of which is cvxmeciCecl to a call multiplexar 24. The operation of coil nZUItiptexar 24 is tuzder directaoxi of a snicrocaa~txolter 26, which may include a voice chip. ~'he output afLC c~s.cillat~r 22 is directted to a peak cl~ctectar 28 whose output is di~rectetl to an aml,litude compar3tor 3Q~ a~~~ t~~e- _ a .feedback control ioQp is genetaLty canaprised of a voltage coxnparatvr ~~.
and a peak daxect~ltmf~e= 36, the output o;~ which is directed back ta~ LC oscillator 22.~ A battery 38 preferably po~uvers inductive sensory aFIP~ 10. A speaker 39 may 'be couneated to mirxacontrollex 26 far activation by ~e voice chip.
IndttctivE sensory apparatus 10 autamati.palt~r adjusts the voXtage dti~rsn~
IJC :~s~:l'~t' ~, by xzxeans of a feedback cdntxu'i loa~p, to keels the peak oscillator amplitude fixed. anei to compensate for variations in.. oscillation amplatvde dus to supply vaitage or temperatxtre changes, or Ct>uiponent ~lerances_ This elianinates tie need for a vcsltage xe~tla'tor in the circuit ~d iacreases the sensiti~rity and dynamic ra~c a of ir~iucfa ,. ~ n ~ «.:. .."..
_. _ . _ . .. .... ..
_ -_r ~ . " .""A,",lr ~'~~~W~B~'cct mu t~p~o ao'n'°~.u~v~e 2~ states.

AftOl~fiLy DOCIC~t~~IO, ~.~11.~2Rf0~0~.
r~
'f6e nuuxber off' sense coils ~0 deprends upon the number of lyits used in the cede patterns to be detected (~tvhich as dictated by tlxe total number of code patterns to be detected ~d the type of codi:rg used, i_e., binary, trinary, etc.) or upon the >mraber of discrete locations v~rhere the prr~eace of ~. conductive object is to be detected. The size cf the coils depends ugoa the sensing distance. Sensing distance, however, is also dependent upon the co~xdoetivit~r of the cond~aetive pattern being detected. Siluer, for examgle, can be dett~cted at a greater sensing distance than copper or aluminum.
In order to keep mufti-bit code patterns a reasonable size, the flat sensor coils are usually square dr round, attd typacally range in sib from. about 0.5" to about ~.8$".
Coals ynay be etched.
1U unto a 1?C beard or printed t~nt~r a non-absor'biug subs~traxe, ~siz~g conduet~ve i~alc. A 0.75" square coil typically. consists of fourteen, turns. Sensing distances Vary ~roxn axottr~d 0.06" usix~ small coals (0.5") up to arr~und 0.2~" with Q_88" sqnaorc aoils_ r.aiger roils, greater than 1'", usnahy are used for the detection of mere than two multiple cozzdnctive states to psavide suf'facie~nt sensor dyna~c range at a reast~x~able sensing dice.
1 ~ Colts 20 may be arranged on the surface c~~ apparaW s 10 its any paktern.
However, i~ the preferred embodiment, coals 20 are arranged linearly inn. rows and columns ~ a checkerboard pattern. Ire an alternative embodiment, coils 20 are arranged izx a series or concentric ~sircles, which peirniE conductirre ,p~erns to be detected even when, rotated rover tlae sense coi,Is. 'Ihe only reqt~ent as to the arrangett csf coils 20 an fibs surfface of apparahu 10 is that the 2Q pattern of coils ZO rarest mateh the patTetn of eouductive etemtats on the abject too 'be lead 6y inductive sensory apparatus I0.
Each. of roils 2~D, ~.t certain times in operatiarrt, acts as the inductor for LC o~sxi.tlat~r ~2.
. .As shown in the circuit diagta~ of Fag_ 2, f,C oscillator 22 is of a standard configuration incorporating a lripolar transistox 4U, a bias resi~stQr 42, bypass capacitor ~1., as well as furst a~tt1 ' 25 second capacitors 46 and 48_ The bate of s6vr 4I1 is tied ts~ gro~md_ Attorney bockei Na_ ~6r 1.02VfOOi Coil anultiplexor 2~ is comprised of a plurality of bipolar transistors 50, i.e., one per each sense coal 20, each of whose emitter is tied to ground, as well as a resistor S~ connected betwc:.en nucrocarciraller 2~ and the base of clt transistor 50. r~lternativoly, cai7 multiple~cor ~~i may comprise an open eolleetor chip, e.g., a 74L.~.156 (octal) or ~4LSOS(hex).
Under direotian of S microcantrollex 2~5, ooil multiplexor 24 operates to ground oz~~e of sense coils ~0 at a time.
Cyrounding sense coil 20 effectively connccts sense tail 2~ to LC oscillator 22 by czeating a ground path throw sense coil 20, thus enabling .'1C oscillator 2~.
Microcontmller ~5 ~is preferably a combination micxocontraller and voice cbag.
Alternatively, the voice chip may be eliminated from miwoconiroller 26, or .a discrete logic ~D controller or ASIC chip may be used in place of microcdntruller 2G.
hfcracozttraller 2G is util~ed, trs sere 'th~raugh the various sense tails 20 so that the state of each sense call 20 rnay be determined.
Peak detecws ~$ is generally comprised of fist cud. second diodes 51, 52, fast and second capacitors 54, Std, a~r~c3 resistor 58. Peak detector ~8 operates to alainp the ~xcgative 15 excutsaan vfthe output of 1rC oscillator 22 to ground and to K:orrvert the positive peak amplitude _ of LC oscillator 22 to a t?C Icvel that can be used for comparison by voltage cornparator 3~.
,Amplitude comparator 3U ins preferably comprised of att operational axnplS~e~c 60 and is used to detect changes in arnplit~zde of oscillation of L~ oscillatoe 22; the rage in ampli'trzde corraspo,nds to a change v~ ir<ductancc of sense coil 213 indicating the conductivity of material Z~ year ser~sc coi! 2D.
Feedback Ioop 32, ag indicated above, Bs generally comprised, of voltage caruparator 3~
and peak detecwrfbuffer 36. Voltage coraparatar 34 is poly comprised of am ap~~tional amplifier B2, a diode 64 'v~tose forward voltage drop is used to establish a 7I1~ mV ice voltage, and a resistor 5~, which biases the referem~e diode 6~. Voltage comparator 34 is used toy 25 compare tlZe DC level oxttput of f,C oscillator 22 to the refe~nce voltage.
'Fha output of ogamp S2 is feel to peak deteet;or/bui~er 9G vs~hpah is venerallu ~~r,ric~rt ~,t' a;n~x~. ~~ ...y.,.~~;t.._ ~n Attorney l~c~cket No_ 2~i 1 _42V1~'001 _g_ aesistor '7~ and bipolar transistor 74, The output of gGa'k detector/but'~er ~6 is supplied as the drive voltage to L~ oscillator 22.
in operatioQ, z»icxoec~r~troller 26 dynannically selects aexy sense ovil 20, which is rust ' covered with conclu~ctive material, to use as a. reference wiI and connects it lm the vs~,iila~r _ c'uc~itry by groc~udutg it thrau~h coil multiplext~r 24, e.g., hripolas transistor SU, to establish the required c~.ve level for LC oscillator 22. The nomunal drive level fir LC
asciliatox 22 is set, 'by selection of the emitter resistar, s_e_, ,resistor 42, to be midway througxs the dynamic range of feedback cr~ntrol loop 32. The peak sense coip amplitude is ciarnped by feedback control loop to a fined reference voltage, a.g., 7t50 .ta.~', so that the other sense coils 2D
r~nay be mvmentasily switched into LC oscillator 22 b~~ micsocc~htraller 26 and c~azaparedwagaiasi 'aide reiesre~nce coin, lvhiah is not affected dry the proxizrrity o~ conductive maternal. Th9s results in greater sensor detection sensitivity arcH dynamic r2,~uge, without circuit adjustments, ar~c~reasing the sensing disfaa~ae form given tail side_ ______ . ____ ._.. _._ _. ___. . ____ _.. ..___ ....._._.____._ _-_ __ .____ r_~_w_...y ... ,...,~ wwv.. wane ~v, ute JU,itJ~l.~4ldllr:C 7iilU
oscillation of the respeot3ve se~ase coil 24 decreases. Tfus t~hange ~in amplitude is detedl by amplitude camparator 30 as at compares 'the oscaliatior~ amplitude agaixtst two or m,~rn reference voltages. The two ar more reference voltages are drcived from the fixed '~04 mY reference t6,a~t is gravided 1by diode 64 and are dynsmi'cslly selected bynicmcontmller 2S by changing the voltage divider, established with. a first . resisoar '7$ and second resistor '7~6, (entd thus, ~rhe ~0 switching threshhoi~ at tho positive in~p~at of amplitude comparator 3C~_ if amplitude cc~mparator 30 indicates that the reference evil amplii'trde is below t'~e first thre~Ynold xhereby implying that ~caaaductive material is covering or ha$ been plaeecl near the selected ze;Fercacs sense coil 20, microcontmltcr 26 operatrs through its sca~ware to dynamiey select $ arevsr uncovered sense coix 20 to use as a refer.
~.5 , ~Vitb. a reference sense coil 2t) established and the drive level for L~
oscillator 22 set, micrvcautroller 26 operates to seqt~e~e thaough the remaining ser~,ss coals 2t1 cran",~,rin~ *~P

~tto~~y ~a~I~e~N~. z~i i.a~wooz _g_ ~aplitude of each sense coil ~0 to at least the 1'itst threshold and, if desired, further thresholds.
In the instance of ctrtriparing the amplitude of each sense coil 20 to only a fxzst threshold, ind~sctive sensory apparatus IO may ha wed t~ produce a binary code that cotrespancts to an idcuti .Fzeation cede printed ari an abject or a location of a. cor~duative object that is within an area covered by sense coils 2U. ~'ot example, each sense coil ~D rnay be assigned a value aiF zero (U3 by microcontsoller 2$ if #here is by clue an induotanre of seanse coil 20 cud, ec~rrespondingly, no rlxange in amplitude detected by amplitude comparator 3~, and each sense coil 20 may be assigxEed a value of one (1~ by microeontrolles Z~ i'>~ them: is any sigz~~ecant change in t>~,e inductat~.c~ of sense coil 20 and, correspond~gty, a change in amplitude detected by ar~aplitude IO carnparator 30. Thereby, rnioxocontroller 26 is able to prode~ce a, banaiy code by sampl~g the ma~ix of sense cans 2Q, In the izrstancc of comparing the anttplitucle o;E- each sense coil 20~ to xnoze than. one tbr~old, inc~ctive sensory ~apparahts 7th may be used to detect gnxtltiple conductive sxates.
Specifically, rich sense coil 20 may detect two or~naore conduirti~re states of iv object xather theca simply detecting rnthether a cottduct;ve material is or is not present.
Intermediate conductive states are coded on an object by the use of pt~iuied shaped cottducixve ink pstherns, for example, where the spacing and width of the stripes varies the conductivity by varying the area of correspoadiung sense coils that is covered Swath tonduc~.ve u~t~:rial, or by embedding dii~'ereut materials thret exhibit different conoquclzvitie',s, e.g_, copper and sil~r, in an object. 'The ability to ~0 defieGt a plurality of conductive si~ttes witlx a staple tail is desirable when objects are either tots small to accommocla2e detection with multiple seaase coils or v~r~he~ra one does xtot want tc~ restrict 'the orientat~n of an.obj~ct, as is usually tequired whey deiec~ting a ~puulti-cell cortduotaive code paten.
her, the ability to detect a plu~atrty of conda~ctive states ena~rles i~rltretiwe sensory appa~tas 1~ to read. trinity rGOnductive patterns and produce a cazresponding trinity code_ Fur example: (1) microcotxCtoller 26 may assi~u ear.F~ of Sen. cnil~ ~ y~r.. rm ;~cf~d..~ :,. ._ _~-.._ ~~~~y ~~~~~~ ~O. ~~~ l.o~.vvoot ' is inductance of sense fioil ~0 (sense cot! 20 is uncovered) ancd, eorresporadingly, no charnge i~
amplitude detected by amplit~xde cornparatoz .~Oy (Z) microcox~troller ~6 may assign each o~ sense coils 20 a area (1) if there is a change in ixtductance c~f sense coil 20 (seosc coil 2.0 is partially coveted) and, correspondingly, e$ere Ss a change in arnpfttude detected by a~glitude cam~parato~r 3~, i.e., the amplitude l~ falllezr below a frrst tlxreshc~l~.; and (3) microco~,tsoller ~b may assign each cl'sease coils ~0 a two (2) if there is a c6atage irx the insl~ctamce of sense coil ~0 (sense coal 20 as completely covered) ~d. coxrespondingly, there is a e'hange in amplitude detected by amplitude comparatar ~0, i.e., the amplitude has fallen below a second tlueshr~Id.
"C~ren x~ssistg txiaary coding, tJxe txtrrnbes of objects tk>at be detected with a given 1tr nuznbex of sense roils 2~ increases dranaatz~ally. ~'ar examlrle, using six 3; ixrch flat, square sense Bails 2U in a seasitxg area of 2~5 ane~.es by t_~ inches, 63 binary codes are capable of beam represented. I~oweve~t, when using trinary coding with the sarce sax sense coils 2D, 7~~
uQiqtre codes can be detectod. xt shouid be noted, however, that trixiary ceding increases the rehired pnsitianal accuracy ~ the placement of priafied code patterns over iradeactive sensory 1~ appeals 10.
Inducti~~c sensory app~atus 1b, a.s descn-becl above, znay be used ixr numerous applications. "d~.ese applications ind~ but are not limited to the ideniif~~catioz~ of cards, tlae deteetzon of different game pieces at various Ic~cations on a game board, ttto detention of an object by tonohing it with the head of a doll ax stuffed toy, and the ideat#ification of moXded ~0 objects yvhe~ placed in any ozzentation on a sensory surface. Tlxese d~eteatic~ns may then be used to trigger audio se~sponses that are produced via. the voice cl~ig ofruicrocomroller 26 acrd speal~er 39. For sample, the hand of a. doll ax stuffed toy may b~e rlesaguecl to cant~itt, a cozrductive ~nxat~aial. The hand ruay rhea be placed over a word or picture of a ho4k that is placed upon a teznglate corra'n;ri '~-~3cr.~~x-y-~ms Itr, v~.fiich includes as plurality of~iat sense coals 25 20 that ate p~riuted an a txex circuit ox et~claed on a PC beard. IJpox~, the iuducd~re sensory apparatus 10 detecting fihe bend, a waral or pluvsc caondeng to 'tlxe selected ~wror~.r~r ri;~"r~

Attorney Docker No. ~611.4217V40~
' -I t-in the bovlC is produced. Alternatiweiy', inductive sensmry apparatus 10 may be incozporxted iuato the book itseif_ 'NoEe that in such a situation, certain se:~se coils 2U of i~duct'sve sensory appaxat~ 10 may be used to detect the location ofthe doll's hand, pointing to a given wore! on a page of the book, whila stir ~sther sense coils ~O.are to detect the identity of the tfook, as S well as the page seleoted (the hand, the pale, the book, etc., are es.G~
coded differentlywith conductive material).
,Software reads the state of several bor~'k coils to dete~~ted a baok >I? code printed an the last page or back cover of the book_ It xeads the state c~f the offset paga coils, where the number viFpage co~7s cnvered with conductive spots on successive p~cges an"diGates the page $eleeted. The I Q' sod then indexes a stored table o.~ r~rcrdlphrase voice rnr~,nry addresses for each book and selects a sr~bset of those addresses rotrespondiag to xhe seiec:ted. page for the selected book. It then detects tire indnvidual ~arord coil covered by rtes doll's hind, casing that inforaoation as ass index to select a partiaalex wares address, vuithin the set o~F pas~ilble voice addresses for the selected page, which cprrtsponds to the i*tdividual word ot~ picture that ;s pouted to on tlxe 15 selected page.
With *eslseat to detecting tha page of a Gook, there exists pxiar art related tc~ rrarivus mechanical ~d eieetrp-mechaW cent mariners of detection. Hovtresver~ these manners ofdet~2ion genex'ally reqeiire electrical cannecti4ns to pages andVor cu~b.vut, azeas in, the pages (e,g., ~or optical detection). Ind~xoti~re sensory aLrpainters 1~ may be used without the priox art 2U rer~emts; as shown ire Fig. 3 each Palo 80 of a boar may be printed with a single conducvive spot $2, a$set ou each page 84, ~veh that tl~e spats 8~ on. cwerlappnug pages 80 cover their respective pogo tail $4 ire, t'he sensory coil pattern. Trr essence the t~g~g oPeach page 8U c~u ba accomplisrced with a single hidden conductive spot $~, axxd thus, tkre detecfiaa of the pages SO
can appear ~aaa~eal to the user. 'Word coils 86 alai then be used to detect various ~woxt'~ 88 on 2S pages . 8D. Note that the eieetcanics of t~ inductive sensory apparatus IO
ate maiu~amedl .Attorney lDooket No, 2ti7.1.02'VUOOI
~~.z pro~eimate ~ coils 84 arid 86 in the back cover of the boom or irt a template to be placed. beneath the nook.
XX. Inductive Sensor~A~paxactus -- Position Sensing Referring to dig. 4, a flat, triangular sevse coil 1t7(f that may be utilized r~ith inductive sensory apparatus 10, iu glare of sense coil ~0, is depicted. Triangular sense cvi1.1D0 xs preferably an isosceles or equilateral triangle with an ixz~aginaey axis I02, wherein imagt~y axis 10~ is de~xmd as the hisector of an angle of the triangle that is pendicular to the appositre side 104 and connects to the midpoint of opposite side 104_ Ttnus, imaginary axis 102 divides triaagular sense coil 100 rratv two syetrieal halves i06_ 1f triangtzltar sense call 1 UO is oorutected to inductive sensory apparat~ I
~ zrn place of sense coil 20, and a piece of eor~dwctive rnatecial that is wider tthe rna~eiut~ width of triangular sense c,~l I00 but shorter titan, its length is moved alcrreg imaginary axis 102 oil tciar~gudar se~zse coil 1 t1(P anr~ in close prdxisrsity to triangular sense coil 100, then the peak detected troltage from LC c~sewlratvr 2~ pmdnr"ed foy inductzrre sc~orry apparatus Itl is linearly l~Po~Qnal to the displacement of the oondnctive mate~ai along imagitlary axis 102 of far sense coil I00. Tri other ~uvords, 'triangular ssnse coil 100 can. be usced to produce a voltage that is proportiox~l to the position o~'a cpncluctive object along the imaginary axis I0~ of triangular sere tail 100 ~d at a fixed distanca from the fat plauae of triangvxllac sense coil Ib(!.
2(~ 'this voltage may 'tl~n be ampli~.ed azld used directly lay iztductive s~dsory apparatus 1t1 as au analog control wolf~,ge, or it may he digi~tixed and used v,~.th a saftwaire lookup table with microcnr~imller 26 to detcrrmine the exact position of the cocductave olbject.
'R~en conductive mac~-ial is positioned tyear the a108 01' triangular sex» coil '1 UO ix covets a very small coal area, while as at is shoved aloe ig~azy axis X~UZ of lsiaug~a~r secase coil 100 nt covers am .
2S increasinglly larger a~eea yvith more coil turns. This causes the selif imdu~nce of fire triaagulxr sense evil 100 to decrease as the conductive xnaterisl brid~ec the f~~,trt ~~.~~ ..,..~ ....~... __~ .~ _ ~txomey Racket No_ 261l.02WOOI

change inn inductance is linear as long as the triangular sexese cod 1Q0 is symrnetzucal about im.agix~ary axis 142. flowevt~r, when the coruductive object reael~es the area of triaz~gvlar sense coil 100 near opposite side 1fl4, where the coil ttnns are perpe~ndi~laa to ipaginaty axis I02, the held bridging effect decreases ao~d the inductance of triangular sense coil 100 may actually begin to it~crea$e_ Therefore, the sensing area to sietect linear disglaceznent extends fromt apes lOB of triangul~ sense coil 100, along imagi~,~ axis 10~, to the edge of the area vvsrhere the coil toms run pe~peiadiauja~r to imaginary axis 102., said edge degi~nated by line 1 x 4.
In an alternative ernbadixnent srf a displacement sensor, a tectarage~lar cox~
which is symrnetricai about an axes, may be connected to inductive sexrsory apparatus 1~_ In trtxis case, a flat sheet of conductive mate~tial yvhen d~cawn~.oss tho xectangutar coi3, in the direction of its axis, covers au increasangly lar~~r.~e~~~f.th;-a~x~r~:~u ptv~nn.~a ~ censor c;oa~trod voltage that is linearly pioporGional to the displacement of the conductive slttet along the coil axis, 'The ability to detect the displacexnant of a conductive object with inductive sensory apparatus I0, using tziangular sense coil 1 U4 or altexx~atively, with a rectangular sense coil, has !S application in position sensing, particularly, for use in controls used in toxic or contaminated environments. Beear~se physical ccutact betwe~an conductive ~xtee~ial and the sense coil is not required, a eo~nhrol xnechaa;~~ utilizing the inductive sensory apparatus 10 is designed to olretate in a. completely sealed enclr~s~, suitable i~Ox such. x toxin or contaminated errvirc~nment, and v~rbich eau i.~ adjusted exCemally froxxi outside tire sealed err~clasure.
Clue specific agpliaatiou is f],~,k f1'F 8.~~.,~~R~.~itP""y"~.,v -- .a~ t . .aa-.____.-_.......... _....._ __-- ~_...~.wv~, ujrv~aa a,~~ellt, etC.
'fhe sealed attenuator is constructed, as shown iu Figs, SA and ~Ha us~g inductive seztsory apparatus 10 with tria.~~'rl~r sense wilts) I~4 with a slirli~;g oonductive bar 112 that mr~~res over triangular sense coils) 100, but is separated from coils) !00 by a sealed hrnrsibg cower 1 ! 3 _ The plane 1 ! S of triangular sense ~ colt 10~, wlrerei~a sense coil 100 is printed rrp a substrate material or etched on a !'C board, cats be seen. in the side 'view nl~t6P atta~ro=9a~+:,. u:..

.~ttar~~y pd~t r~o. ~m ~.ozwoa~

5~. .A.s stun arso be seen in the side vievr ofthe attenu~,tor, slidiFag conductive bat 11~ preferably includes side tabs 116 that allr~w bar 112 to slide below a aantral panel cower 114 while at the same time being held captive by cav'er 1 I4.. As the pasitx~ of the attenuatar control is moved, a Voltage pa;oportional fio ifs positive xs produced lry inductive sensory apparatus lt?y anal is used tc control a voltage controlled resi$trve element, #ae speed ~r~ machinery, or its any application, that ___._Tr~~~u'.be.rox~ficnlI~d.hv a.xa~ablP..D~uQ~~.~-~~tn;cr~oll~: .A.""Y'W ~
a"gyii4 iR'via 'vi iiuutiLiivG
sensory apparatus 1 a with triangular sense coil 1 Oi) includes de'Daeting ttae ppsition of s aonductxve object with high resolution, i~.e., where a continuurxt of positions must be detected, rather than just a~ sages ' of discrete positions, rDf coeirse, rturueraus otrtle~r applications of _ T.., _ ...,...~.. o.. ..
yn ;",~,y",~;,,d..,~.~.,.,.-_..,___.._~__ ",___-.t ., - _ . _ _"_. _ _.~~. ".
from the spirit or scc~pa of the invention.
the present i»vett~iora crtay be ~;ttabodied izu ether spcc:i~io farms wvithou~C departing from the spirit of the essetztial attributes thereof; 'Eherefore, the illustrated etnbQdiments should 'be considered in all respects as illustrative and aot restxiative, ref'~erence iteing ctaade to the appended 15 alaixrts ratlxer than to tJ~e faregai.~ag description to indicate the scope afthe invention.

Claims (20)

1. Win. inductive sensory system for identifying or detecting a conductive object or a conductively coded object, said inductive sensory system comprising:
a sense inductor;
a sense inductor used as a reference;
an oscillator connectable to said sense inductor and to the reference sense inductor, and a feedback control loop, wherein upon said oscillator being connected to the reference sense inductor sand feedback control loop establishes a fired reference level;
and a comparator, wherein upon said oscillator being connected tai said sense inductor, a state of said sense inductor is compared by said comparator against a threshold derived from said fixed reference level to determine the change in inductance of said sense inductor.

2. The inductive sensory system of china 1, further comprising a processor, wherein said processor selects between said sense inductor and the reference sense inductor for connection to said oscillator.

3. The inductive sensory system, of claim 1, wherein said feedback control loop maintains said reference level substantially independent of a variation selected from the group consisting of ambient temperature variations, supply voltage variation in a supply voltage to said inductive sensory system, and component tolerance variations ins a component of said inductive sensory system.

4. The inductive sensory system claim 1, wherein said conductively coded object is selected from a group consisting of a plurality of cards, pictures, molded figures or shapes, game pieces, vehicles, or puzzle pieces.

5. The inductive sensory system of claim 1, wherein said sense inductor comprises a flat sense coil and wherein said flat sense coil is embedded within an object, said object selected from a group consisting of: a book and a template positionable beneath a book, and wherein said conductive object comprises a page within said book.

6. The inductive sensory system of claim 5, wherein said conductive object comprises a plurality of pages within said book and wherein each of said plurality of pages includes a conductive material, and wherein each of said conductive material as offset on said page from said conductive spot on the next proximate page.

7. The inductive sensory system of claim 1, wherein said sense inductor comprises a flat triangular sense coil or a rectangular sense coil.

8. The inductive sensory system of claim 7, wherein said triangular or said rectangular sense coil has an axis and wherein said inductive sensory system detects the position of said conductive object along said axis.

9. The inductive sensory system of claim 8, wherein said inductive sensory system is implemented within an attenuator or slide controller, where said conductive object comprises an adjustable bar or knob that slides over said triangular or rectangular sense coil to produce a control signal.

10. The inductive sensory system of claim 9, wherein said control signal is suitable for controlling audio volume, motor speed or temperature.

11. An inductive sensory system for identifying or detecting a conductive object or a conductively coded object, said inductive sensory system comprising:
a sense inductor;
a sense inductor used as a reference;
an oscillator connectable to said sense inductor and the reference sense inductor;
and a comparator, wherein upon said oscillator being connected to each of said sense inductors, a state of said sense inductor is compared by said comparator against a plurality of thresholds derived from a state established by the reference sense inductor to determine the change in inductance in said sense inductor.

12. The system of claim 11, wherein the comparison of said state of said sense inductor against a plurality of thresholds enables said inductive sensory system to detect multiple conductive states in said conductive object.

13. The system of claim 11, wherein said sense inductor is used to detect a plurality of conductive objects at a given sensing distance independent of the orientation of said plurality of conductive objects.

14. The system of claim 13, wherein each of said plurality of conductive objects is encoded.
to exhibit a different conductivity, said plurality of conductive objects encoded according to a type selected from a group consisting of: a material encoding and a printed pattern encoding.

15. The system of claim 12, wherein said conductive object encoded with a trinary path and wherein said inductive sensory system detects three distinct conductive states.

16. The system of claim 15, wherein said three distinct conductive states are selected from a group consisting of: a state of being covered with a conductive material, a state being uncovered by a conductive material, and a state of being partially covered with a conductive material.

17. The system of claim 13, wherein said plurality of conductive objects comprise a plurality of fame pieces and wherein said sense inductor is incorporated in a game board.

18. The system of claim 13, wherein said plurality of conductive objects comprise a plurality of molded objects and wherein said sense inductor is incorporated in the base of a playset or mat upon which said molded objects are placed.

19. The system of claim 13, wherein said sense inductor is incorporated in a doll, soft toy, puzzle, vehicle, or card reader.

20. The system of claim 11, further comprising a feedback control loop, wherein upon said oscillator being connected to said reference sense inductor said feedback control loop establishes a fixed reference level.