CA1323916C - Apparatus for remotely determining the angular orientation, speed and/or direction of rotary objects - Google Patents

Abstract

ABSTRACT

A circular array of equally spaced, identical stationary electrodes is arranged about the center of the array and a rotary electrode is arranged on a surface of a rotary member to be monitored in such a manner that M among N stationary electrodes have a maximum capacitance by being in confronting relationship to the rotary electrode according to the angular position of the rotary member, a maximum capacitance is in proportion to the azimuthal angle of the radius as measured from the leading end of a stationary electrode. The angular position of rotary member is identified by signals from the stationary electrodes which are in confronting relationship to rotary electrode, by measuring the output signal corresponding to their maximum capacitance when scanned by the rotary electrode.

Description

~3~39~6 QPP~RQTUS FOR REMOTELY DETERMINING T~IE ~NGlJLAR ORIENT~TIO~.
SPEED AND/OR DIRECTION OF ROTARY OBJECTS

BACKGROUND OF THE INVENTION

The present invention relates generally to a remotsLy read1ns maans for detsrm1nins ths angular or~entation. speecl and/or direct10n of rotarY obiects such as shaft. dial or meter hands. counter wheel of cYclometer. ancl the li~e. More particularly. this invention is concerned with electrically obtaining a signal that is indicative of the angular orientation.
speed and/or direction of rotary objects to be monitored without alterins ths accuracY and opera-tion of tha conventional utility meters or the li~e.

In electric utility system. for instance. sufficient power-generating equiprnent must be Prov1ded at Hll time to supply powar dur1ns relat1velY short period of maximum consumption.
however much of this equipment otherwise remains idle for maior portion of each day. In order to d1scourase hi9l1 power consumption during maximum-demand periods by graduated bill1ns rates. or evsn to disconnect non-essential portions o-f customer's load when the customer exceeds a previously asreed consumption rata compatible w1th the optimum seneration capacity of the ut1lity companY. rapid determ1nat10n of an 1ndividual customor's consumptlon rata. comrnonly termed "clemand" over a Prescribed tirne interval is necessary. '?.

:~

' :' 1323~6 Heretofore. such demand me-terins has senerallY bsen posslble onLY throush the use of speciaLly equipped meters. commonl~
Limited to a fixed time interval and not capable of transm;tting informat1cn upon cIernanrJ to a load~ clnltor1ns s-ta-tion In time for ths statlon to ta~e corrective action. There has been considerabLe effort expended 1n prov1dins means and apParatUs for reading meters at a distance. for example. through telephone llnes and the li~e.

There maY be four catesories in remote rneter read1ng means:
photoelectr1c ceLL; sLidins mechanicaL contact; masnetic f1eld;
and eLectrlc fieLd.

The photoelectric cells have been used in mster readlng dev;ces. so that no mechanical connect10n i5 needed between the metsr and the meter raader~ However. these read;ng devices have been unsat1sfactorY because a reliable source of l1sht must be provided and the face of the photoelectr;c cell must be ~ept suff1c1sntlY clean so that the Lisht imp1ns1ns on the hotoeLectric ceLL wiLL not be cIiminished suffici~ntLY to sive a false read1ns.

The slldlng mechanical contact sensor has been used ln Neptune's ramote meter readins systeIns srantad the U.S. Patant No.3.614.774. The use of such sensor ls prevented in exploslve atmospheres. and in certa1n instants. changes in the output slgnal have been noted due to tha asins of the components whlch can chanse its mechanicaL and~or electricaL
character1stics. ' Thls type of sensor can not be used for - ~
~ .

~32~

metars whlch must havs h1sh sensitiv1ty such as WatthDur meters.
because its high Prsssure on contact.

MasneticallY 1nducsd reading system was 1nvsntsd by Cain who obta~ned the U.S. Patent No.3.500.365. on 1t. Ca1n 1nvented an ~mproved electrically ~nduced readins system bY usins an electr1cal transducer unit lnstead of ths masne-t1c coupling and obta;ned the U.5. Patents No.~.007.454 and No.4.429.308.
This ssnsor has h19h resolut10n because the Phase of the output s~gnal of the sensor is detected tD detsrmlne the ansular or~entat10n. sPeed and/or d1rsction of rotary ob~ects.
In order to aaslly detect ths phase of the outPut signal. h1sh frequsncy 1nput signal has to be used. and thersfore. the c~rcu1t accompany1ng the sensor bscDmes compl1catsd and expensive.

Capacit~vely sensing dBViCB for remotely determining the angular or1entation. speed and/or direction of rotary obiects was inventsd by ths inventors of this invention and was f~led at the Off1ce of Patsnts ~dministration of Korea on ~pril 15. 1985.
The output s1snal of the caPacitive ssnsor is in propDrt10n tD
the caPacitance b~twsen a statiDnary electrods and a rotary electrode. The rotary elsctrode has a physical coupling means to electron1c c1rcu1t which can be provided at a lDw Price.

However. the capacit1vetY sens1ns device also has the l1mltation 1n the appl1cation to the r~tarY ob~ects w1th very h1sh speed or small si~e because the area of a stationary electrode 1s the same as that of sa1d rotary elsctrode.

.

- ,.

~3239~ f~

There i5 thus a neecl to Provltle an lmproved apparatus for determinlng the ansular orientation. speecl ancl/or direcL;on of rotarY obiects wlthout PhYsicallY connecting tha rotarY objects to the measur1ng devlce.
; Moreovsr. there is a need to provide an apParatus having an lmproved chflracterlstics so as to aPply lt to a ro-tary ob~ects with small size.

It ls accordins~Y an ob~ect o-f the present lnvention to provlde ths capaclt1vely sens1ns device hav1ns 1mproved characteristics and the capacitivsly readlng aPparatUs which consists oF said capacltivelY sensins device and circuit being manufactured at a very low price. for automat1cally readins the indication of counter wheel or of Pointer of the conventional UtilitY meters such as Water meters. Gas meters. and the like.
1~ without effecting the accuracy and oleration of the conventlonal ut1lity meters.

It ls another ob~ect of the lnvention to provide a capacitively reading aPParatus with imProved resolution so as to remotelY read the ansular position of a rotary objects with small 2 s1ze.

Wlth the appara-tus beins clescribscl hereln. anY utlllty meters which are mechan;cal resister tYpe or pointer tYpe can be read by the load-monltorins station with extrems speed permltt1ns the readlng ~of many meters duril1s a short tlme per10d. as well as ~5 taking several sample read1nss from each meter to increase the statistical validitY of the readinss. Thus ths utllity company S
.,: , .

' : ., , ,; ''''` : ' ~L32391~

can determ~ne not onlY the total energY consumed by any 1nd~v1dual customer dur1ng a normal b1ll~ng per10d. but also can mon1tor h~s demand rate durl~g any des1red t1me 1nt~rval.

': ' ' ' . . .

.

~ ~3~

SUMM~RY OF THE PRESENT INVENTION

Thoss ob~ects. as well as further ob3scts wh1ch w1ll becomo appar0nt 1n the d1scuss10n that follows. are achieved. accord~ng to the present 1nvent10n. by prov1d1ns an arransemsnt of rotary el0ctrod~ lylng subs-tant1alLy on a surface of rotary ob~ects to bs mon1torsd and an arrangement of stationarY e~ectrodes. to be descr~bsd below. 50 US to construct capac1tors accord1ng to the angular Pos1t10n of the rotary obiects bY b~ng 1n confront1ng rslat~onship to sa1d rotarY electrode.

There maY ba daf1nsd as manY d1scr~ts capacitors betwsen sa1d stat10narY electrodss and sa1d rotary electrode as the number of said stat10nary electrodes. However. the capac1tors of tha stationarY electrodes which are 1n confront1ng rsl~t10nsh1P to sa1d rotarY slectroda havs the max1mum capac1tanca. Therefore. the angular pos1t10n of sa1d rotary slectrods can bs determ1ned bY finding the stationary el0ctrodes hav1ns sa1d maxlmum capac1tanc~.

Because a plural1ty of stat10narY el0ctrodes const1tuta the capac~tors hav~ns max1mum capac1tance by be1ng ~n confront1ng relat10nsh1P to ona rotarY 0lectrode. the capac1tors hav1ng ths maximum capac1tancs can bs cons1dered and rneasured as one aquiva~ent caPac1tor connacted s1th~r ln s~r1ss or ln parallsl.
~ccording to the conn~ctins methods. e1ther 1n ser1es or 1n parallel. manY sens1ng devices havlng d1fferent advanta3~s are obta1ned.

~ . .

.

~32~91~

In any case. the ansular positic)n of said rotary e~ectrode is ldentified bY the number of the s-tationary electrodes havins said maxlmum capacltance.

In accordance with one aspec-t o-f the lnven-tion. there is provlded ~ capacitively sensins clevice for monitor1ns said rotarY
electrode bY connect1ns onlY saicl stat10nary electrodes to electronic circult accompanying said sensing device without PhYsical contact with said rotary electrode.

In accordance with another asPect of the ;nvention. there is provided a capacitivelY sensins device us;ns wires much less than the number of said stationarY electrodes for connectlng said stationarY electrodes to said electronic circuit bY
interconnecting said stationary elec-trodes themselves ;n a part;cular mode.

In accordance w1th another aspect of the ;nvention. there is provided a capacitively sensing device having the sffectively 1ncreased maximum capac;tance. which ~s larser than that defined between each of sald stationry electrodes and sald rotary electrode. bY means for electrically connectins said rotary electrode to said electron;c circu;t.

In accordance with another aspect of the invent;on. there ;s provided means for senerat;ns a code ;nd;catlng the angular posit10n of said rotarY electrode bY scannlng sa;d statlonary electrocles for inp-l-t and/or output si~nal~ and bY measllrins the max1mum output s;gnaL ow;ng to sald maximum capacitance of the .
capacitors ex1st;ng between said stationary electrodes and sald :, -.: :
.
- ~

~323916 rotarY elactrode.

In ~ccordflnc~ with another aspect of the invant1an. there ls providad maans for convertins said coda 1nto a moduLated s19nal to be transm1tted to a d1stance through 2-wlre trHnsmission lins.

In accordance w1th another aspect of ths invantion. there ~s Prov1ded means for improv~ns the rssolution of said caPac1t1velY
readlng apparatus by uslng ~/D convarter to detact the output s~snal of sa1d cap~c1t~vely sensing dev1ce in oder for said capacit~valY sensing dsv1ce to be adapted to remoteLY read the ansular pos1t10n of rotarY ob~ects such as polnter-type 1ndicatior as well as the 1ndicatins numbsr of counter wheel.

Still other ob~ects and features of the pressnt invant10n will become more raadilY apparent to those s~illed 1n the art from the following dsscriptions when rsad in con~unction w1th the accompanYins drawings. whsrain there are shown and described the Pr~farrad embod~ments of the invent10n s1mply by way of 1llustrat10n of one of tha best modes contemplated for carry1ns out th~ lnventlon. As will b~ rsal1zed. th~ 1nv~nt10n ~s capable of o-ther. diffarent. embodiments and 1ts several deta~ls ars capabla of mod1ficRtions in various obvious aspects. all w1thout depart1ns from the 1nvention. ~ccordinsly. th~ drawinss and dsscr1pt1Dns w1ll be resard~d as illustrat1vs in natur~ and not as restr1ct1v~.

: ~ , . . .

~ ,, ' ~ .

13%3~16 BRIEF DESCRIPTION 0~ THE DR~WINGS

Flgs. l~-lD are schemat1c dlagrams show~ns a pr10r art sens1ng dev~ces useful 1n measuring the angular or1entat10n.
spsed and/or dlrect10n of rotary ob~ect6;

F1s. 2Q 1s a mechan1cal reg1ster set wh1ch cons1sts of several countar wheels for & cyclometer;
F~s. 2B 1s a plan view of a counter whesl obssrved from th~
l~ft Df F~g. 2Q;
F1~. 2C 1s a s0omatr1cal descr1pt10n of an electrods to be used for th1s exemPlarY embod1ment;
F1g. 2D 1s the same f1gure of F19. 2B except that a rotary electrods dascr7bed ~n Fig. 2C is arranged on a cross-sect10nal surface of counter wheel. whoss central angle ls selected to ba 72 d~grses;
F1s. 2E 1s a clrcular array of 10 stationary elactrodes whose 1nner and outer rad1i are the same as those of the rotarY
eLactrodes. resPsct1veLY. ~nd the central nn~le of the cone 1s less than that of the rotarY electrode;
F19. 2F 1s a plan v1~w of a Prefarred 0mbod1mant of the sens1ns devlce accord1ns to th0 Present 1nvent~on;
F1s. 2~ 1s a slde V1BW of ths sens1ng devicr shown 1n F1g.
2F;
F1g. 2H is an electrlc capac~tor model of F19. 2F;
F1g. 2I 1s a simPL1fied circuit model of F1s. 2H;

F1ss. 3~-3J are sets of stat10nary electrodes 1n confront1ng relat10nsh1P to sa1d rotary electrode accord1ns to the an~ular '' 10 ~ 3~3~6 position of rotarY obiects. wh;ch are obtainecl from the sensing d~vlce of Fis. 2F;

F;s~ 4Q ;s a funct10nal block diagram of the apparatus accompanyins sald sens1ns dev1cc described in Fig. 2F;
Fig. ~B 1s ths correspond1ns relationship betwe6n the code generated from scannlng counter. each set of two stat10nary electrodes to be in confrontins relationship to said rotary electrode. and the lndlcatins numbor o-f counter wheel be1ng obta~ned from the apparatus of Fig. 4A;
li) Fiss 4C-4E are the rnodi-f1ed apparatus accompanyins said s~ns1ns device of Fi~. 2F;

F1gs. SA-SH are the tyPical waveforms belng observed at various po1nts of the circuit of Fig. 4;

Fig. 6Q-6C are the plan view of two counter wheels lndicating the number nf two figures. in which the indicating number ;s changins from 59 to 60. and its electrically equivalent cDpacitor model. resPect1velY;
Fis. 6D-6F are the typical waveform be1ng observed from said apparatu3 of Fig. 4E for the case of Fis. 6~;

F1g. 7 is another mod1fied apparatus accompany1ns sa1d sensing device described in F1s. ~F. from which the high resolution is obtained;

Fig. 8 is a plan view of an alternative embodiment of the sensins devlce accordin~ to the PresellL lllvenLlon;
Fig. 9 is a mod1fied apparatus acComPanYins sa1d sens1ns ;

~ ' ' : " .

~323~$

d~v1cs of F1s. 8;

Flg. 10 1s the corresponding relat10nship between the code senerated from scAnnins counter. each set of two stat10rary el~ctrodes to b~ ln confront1ns reL~t~onsh1P to sa1d rotary e~ectrode. and each ~nd1cat~ns number of counter wheel be~ng obtc1ned from sa1d ~pparatus of Fis. 9;

F1s. llA-llE are the tyP~cal waveforms be~ns observed from the c1rcuit of F1s. 9 when the ;ndicat1ns number is 4 and ~s ch~nsSns from 6 to 7. resPect~lvely;

F1g. 12~ and 12B are the plan v1ew and the side v1ew of another Pr~ferred feature of ths invent10n. respectively;

Fig. 13~ ~nd 13B are the electrically squlvalent capacltor model for the sens~ng dev;ce of fig. 12A;

Fiss. 14Q ls another modif1ed aPparatUs accompany1ng said sens1ns dev1ce of F;s. 12A;
f1s. 14B is the corrsspond1ng relat10nsh;p between the cods generated from the apparatus of Fis. 14~. each set of two stat10nary el~ctrodes be1ng in confront1ng rslat10nshiP to sa1d rotarY electrode. and the 1ndlcat1ns number of countar wheel to b~ mon1torsd;

Fiss. 15 1s another Preferred embod1ment of said sensing dev1ce of F1g. 12Q;

Flgs. 16A 1s another modifisd apparatus ~ccompany1ns a1d sens1ng dev1c~ of f1s. 15; and .
, \

~323~

Flg. 168 is the corresponding ralationshiP between the code generoted from the ~pp~rQtus of F-s. 16A. ehch set of two st~t10n~ry electrodes be1ng 1n confront1ns rsl~t10nship to s~1d rotarY electrode. and e~ch 1nd1cat1ns number of countlr whe~l to ba monltored.

, " ' ;
:: - .

~32~3~

DETQILED DESCRIPTION

TYP1cal Prior art sensing dev1ces of the angular or1entat10n. spsad and/or d1rsct~on of a rotarY ob~ects are 1llustrated bY tha conf1surat10ns of F1ss. l~-lD. The ssns~ns S dev1ce of F1~. lA cons1sts of the comb1nat10n of several l1ght sourcas. phototrrns1stors and a rotarY encoder. The ansular or1entat~on. speed and/or d1rect~on of a shaft ~s the same as those of th0 rotarY sncodPr because the rotarY oncod0r ls f1xed on ths shaft to be monitored. Therefore. the angular Poslt1on of tha shaft 1s determ1ned from the output s1gnal of the hototrans1stors. This 1s a verY s1mple and most effect1va sens1ns dsv1ces because of its very h1sh resolution. Its resolut10n is about 1.4 d0sree when th~ rotary encoder has 8 slots ~n a r~dlal llno. However. th~s device 1s applied to the llm~ted area such as motor controller where there ~s enough room to 1nstall the sens1ns dev1ce.

Flg. lB 1:s another pr10r art sens1ns dsv1ce us1ng mechanicallY sl1d1ng contact. Th1s sens1ng dev1ce cons1sts of stat10narY electrodes arransed 1n a o1rcular array and rotarY electrode wh~ch 1s f1x0d on tha rotarY objacts tG be mon~tored and ~s sl1d1ng on the stationary electrode array.
Th~s sens1ng devlcH has normallY one contact betwsen a rotary electrode and ona of 10 stat10nary alectrod2s correspond1ns to ~ach of 10 d1screte angular pos1t10ns of the rotarY ob~ects.

.

~3~3~1~

Tha angular pos1t1cn of ths rotary objects 1s very eas1ly determ1nad by the contact because the contact 1s machan1cally made. In ord~r -to 1mprove thfl resolut10n of th1s sens1ng dev1ce. the rotarY electrode 1s made hav~ng A very n~rrow w1dth.
Th1s narrow w1dth of the rotarY ~lectrode maY ma~e the contact d1sconnscted from any stat10nary electrod 2S when the rotary electrode 1s located in tha gap between two stat~onary electrodss In order to avo1d th1s s1tuation. two ad3acent stat10nary electrodes hava the 1nterleaved parts at both snds as shown 1n F19. lB. These lnterleaved parts of two ad~acent stat10nary electrodes ma~e two contacts tosether with nne rotary electrode.
A spec1al code to dist1nsu~sh the axact an~ular Pos1tion of sa1d rotarY 0lectrode from those two mechan1cal contacts was 1nventad by NePtune company. granted the U.S. Patent No. 3.614.774. But the mechanicallY slid1ng contact ~s not suitable for remot~lY
read1ng the sens1tive maters such as Watthour msters because of ths h1sh PressUre on its contact.

F1s. lC shows another excellent pr1cr art sens1ng dev1ce to determ1ne the ansular or1sntat10n. s~eed and/or d1ract10n of rotary ob~acts by electrlc and/or magnet1c f1elds. granted tha U.S. Patent No.4.429.308. Owing to the part1cular1ty of crsscsnt-shaped electrodes the area of the stat10n~ry electrodes which 1s undsrlYing and fac1ns the rotarY electrod0 1s ProPort1onal to the s1nas of A~. ~ 1s an arbitrarY constant and 0 1s an anglo def1ned as the an9ular d1stance betwesn the rotarY
elactrode's pos~it10n and the a21muthal an9le at wh1ch ths rotary lS

`

~323~6 electrode f1rst oncounters the stat10narY elactrode dur1ng ths hypothet~cal rot~t10n. Becauss the ~rea ~s ~n Proportlon to the s1n~s of Aa. the capac1tance between stationary electrode and rotary electroda 15 also 1n Proport1on to ths s1nes of QF. ~s a result. what to bs measured 1n order tD detsrm1ne ~. the ansular poslt10n of rotarY electrods. ls the relatlve phase o~ the output s~gnal wh~ch ls a funct~on of tha capac1tance.

The elactron1c c1rcu1t for detect1ns tha Phase of a s13nal 1s usuallY compl1cated and expens1ve. Therefore. th~s sens1ns dev1ce ~s not Yet put on a commerc1al bas1s becausr of lts h19h Pr1ce .

F1s. lD 1s nnother pr10r art sans1ns dev1ce 1nvsntsd by t~e inventors o~ the present lnvention and was f1led at the Off1ce of Pat0nts ~dm1n1str~tlon of Korea on ~Pr1l 15. 1985. Th1s sens1ng devlc~ also ccnslsts af an arraY of many stationary electrodes and a rotary electrod~ wh1ch 1s 1n confront1ns relat10nsh1p to onlY one of ths stat10narY ~lectrodes accord1ns to the d1scrste ansular pos1t10n of the rotarY elactrode. When ths ansular d1stance 8 1s def1ned as ths sama way as 1n the sans1ns dev1ce of 20 F1s. 1C. ths cap~c1tance betwacn stat10nary elactroda and rotary electrode 1s d1rectlY 1n Proport1on to ~ 1nstead of the s1nes of ~a. Thus~ tha outPut s1snal of tha sens1ns dev1ca of F1s. lD 1s alsG d1rectlY 1n proPort1on to q and ths ~lectrDn1c c1rcu~t accDmpany1ns th1s sansins d~v1ca can ba prov1c?ad ~t ~ low Pr1ca.

Even though the senslns dPv1cs of F19. lD has several advantagas ovar tha other sans1ns dev1css. 1t also has a shortcom1ns ~n :

- ~ i r ~3~3~

certa1n aPplication such as read;n~ tha ind1cation of rotarY
ob~ects whose speed 1s v~ry h1sh. or whose slze 1s small.

In order to overcome th1s def1ciencY 1n the prior art. there 1s thus provlded the 1mproved rapac1t~vely ssns1ng dsv1ces and an apparatus accomPanY'ns said sans1ns davicas so as to remot~ly determ1ne the ansular Pos1t10n. speed and/or d1rect1Dn of rotary ob~ects.

In accordance w~th pr1nc1ples illustrat1ve of the Present 1nvsnt10n. f1ss. 2A-2I descr1be the exemplary arransement o~
rotarY and stat10nary electrodes in ordar to obta1n capac1t~vely sens1ng dav1ce. The exemplary embodiment of said sens1ng dev1ce explains how to read the 1nd1cat1ns number of ut1l1ty meter at a distance accord;ns to the 1nvent10n. w1thout affect1ns the accuracY and operation of the convent10nal ut1l1ty meter. and wh1ch part of the convent10nal ut1l1ty meter and how much to be mod1f1ed for adopt~ns the Present invent10n.

F1s. 2A shows a res1ster set of counter wheel wh1ch 1s assumsd to be a rotarY ob~ects to be mon1tored. F1s. 2B 1s a plan v18w of a counter whecl 50 observed from the left of F~g. 2A.
Counter whsal 50 has sencrallY 10 discretQ an~ular Po~it10ns flnd the number~ 0 to 9 are des1snated on 1ts cYl1ndr1cal surfac~
according to each of 1ts 10 angul~r positions.
Counter wheal 50 rotates 1n the direct10n that shows each numbor in ascend1ng order when read from the reference Point at 12 o clock .

;: . ~. : : . .

. , ~23~6 Fig. 2D shows the exemplary arransement of rotary elcctrode. 1n which a f~n-shaPed rotarY electrode 52 who~e ~eometr1cal descrlPtlon ~s shown in fls. 2C ls arranged on the cross-soctlonaL surf~ce of countar wha~l 50. ~he rotarY alactrode 52 1s to ~ monltored to 1dent1fY the angular Posltlon of rotary ob~ects. tha lndlcatlns number of counter wh0sl 50. The central angle of rotarY electrode 52 1s selected to be 72 degreas for ~ claar 1llustration.

~ rotarY electrode 52 1s arransed on the cross-sectlonal surface of a rotarY ob~ects to be monltored for the example Gf F1s. 2D.
but can be arransed on any surface such as the cyl1ndrlcal surfaca of counter wheel 1n an approprlate shapa to the surface.

Thus, rotarY electrode has been Prepared on a surface of rotary obiects to be monitored for th~ exemplary embodiment of ~he 1nYent10n.
' Many fan-shaped statlonary electrodes are arranged on a statlonary plane member ln a circular array. becausP sald rot~rY electrods 52 lylns substant1ally on the cross-sectional surface of counter wheel 50 ls a fan-shaped plate.
flg. 2E shows a plan vlew of 10 fan-shaped statlonary electrodes arransed 1n a c1rcular arraY on a stat10nary Plane member 60.
The number Df ~ald stationarY electrodes 1s selsct~d to be 10 ln ordar to eas1lY understand the pr1nc1ple of the lnv~nt10n bY
match1ns ths number ass1~ned to each stat10nary electroda to the - :
, - ~

," ' :

~323~1~

number ass1sned to each ansular Pos1t10n o~ rotarY ob~ects to bs mon1tored. Therefore. the area of rotarY electrode 52 1s tw1c~ that of a stat10n~rY electrode. In other words. two ad~acent stationarY electrodss are 1n confront1ns relat10nsh1p to sa1d rotary electrode 52 ~or the exsmplary embod1ment of F1s. 2D.

Thus. an array of stat10nary electrod~s has been prePared on a st~t10narY plane member for the exempLary embodiment of the 1nvent1on.

~ capac1t1velY sens1ns dev1ce 1s prov1ded by pos1tion1ng tha stat10narY member ~0 so as to be 1n confrontins relationsh1p to cnd 1n Parallal to the c1rcumferent1al path def1nsd bY said rotary electrode 52 to be mon1tored.

Fls. 2F shows the pLan vlew of th~ c~pacltlv~ly sanslns devlca.
~h1ch 1s ths exemplarY embod1ment to expla1n the Pr1nc1ple of the 1nvent10n. Fis. 2G 1s the s1de v1ew of the sens1ng dev1ca of Flg. 2F. The numbars ass1sned on the cYl1ndr1cal surface o~
counter wheel 50 are des1snated on the outer c1rcle of Fig. 2G.
Each number des19natad 1ns1de the c1rcle 1s corresponding to eàch of 10 stat10narY electrodes.

Then. the odvancsd number of the two numbers ass1gned to the two stat10nary elsctrodes beins ~n confront~n~ ralat10nsh~p to rotary electrods 52 1s equal to the ind1cat1ns number of counter wheel 50. Mflans for connecting said sens1ns devlce to alectronic c1rcu1t accompany1ns sn~d ~sns1ns d~v~cs 1s ach1~ved bY w1res ~ ~ `
.
~i ~

~23~ ~

~0 connected to only sa~d stationary alectrodes.

In the sens1ns devlca of Fls. 2F. 10 d1scrate capac1tors can ba deflnsd batween 10 stationary electrodes and one rotary 0Lectrode. Howsv~r. 2 of 10 c~pacltors have a domlnant.
max~mum. capac~tance. because two stat~onary electrodes are ~n confront1ng relot10nsh1p to sa1d rotarY slactrode. The capacltanca of othsr caPacltors can bs 1snorsd. Thsn. sa1d sens1ng dsv1ce w~th 10 stationary slectrocles can be represent0d by two capac~tors ln the v;ewpolnt of electronlc clrcu1t elements accord1ns to the ansular pos1tlon of ss1d rot~ry electrode.

F1s. 2H shows the capac~tor model for the case of F1s. 2G
accord1ng to th~ above dRscr~pt~on- where two capac1tors are connected ~n ssr1ss bY s~id rotarY slectrod6. Each of two stat10narY el~ctrodes whose numbers are 9 and 0. resPect1velY.
constructs the capac1tors. hav;ns the capacltance d3signated by Cmax. by be1ns ln confrontlns relationshlp to rotarY Plactroda 52 The m~x1mum capac1tance Cmax 1s def~ned as follows:

~ 5 Cmax ~. .
. whare S 1s tha area of a stot10nary a~e~troda. d ls ths d1stance batween the statlonary mPmber 60 and the rotarY
electrode 52. and - ~s the permitt1v1ty of the d1electr~c .

.

, ' ~ 3.~39~

betwe~n said stat10narY electrode and sa;d rotary electrode.

Because rotarY elec~rods 52 is cons1d~red as a common conductor for the two capac1tors. as shown 1n F1g. 2H. F1g. 2H 1s represented by on~ equ1valent capac1tor. hav1ns the max1mum capac1tanc~ des1snated bY Cm as shown ~n F1g. 2I.

F1s. 2I shows thut 2 of 10 stat10nary elsctrodes. the number 9 stat10nary electrod~ and ths number 0 stat1Gnary electrode. ar~
coupled to each other by the max1mum capacltance Cm. and other station~rY eLsctrodes maY be cons1d~red as opsn circu1t elements.

Thus. two stat10narY electrodes are couplsd to each other by the m~x1mum capac1tance Cm onlY when both two stat10nary electrodes are ln confront1ng relat10nship to sa1d rotarY electrode.
Ther~for~. the ~ngular posit~on of sa1d rotarY electrode can be un1quelY ~dsnt~f1cd bY flndlng two stationary elsctrodes hav1ng the max1mum capac1tanc9 Cm. The h1gh numbsr of the two stat~onarY electrodes wh1ch are coupled to each other bY sald rotary alectrods 1s ~qua~ to tha 1nd1c~t1ns number of counter whse l 50 .

The max1mum capac1tance Cm between a coupLe of stat10nsry elsctrodes wh1ch w1ll be used for determ1n1ns the angular pos~t10n of sa1d rotary electrode 1s def1ned as foLlows;

Cm = Cmax / 2 F19s.3~-3J show each set of two stat10narY eLectrodes wh1ch ~are capac1t1vslY coupled to each othsr by the maxlmum capac1tancs .
.. . .

~32~

Cm. beeause the two stat10nary elertrodes are in confrontlng relat10nsh1p to rotarY eleetrode 52 Each ind1cat1ng number of counter wheel 50 ~s ld~ntlf1ed from tha h1sh number of sach s~t shown in F1~s. 3A-3J.

Thus. there 1s prov1ded a capaclt~vsly sens1ng dsv1c~
prov~d1ng the corresPonding relat10nsh1P between ths numb~r ass~gned to each stat~onary elec~roda and tha 1nd1cat1n~ number of counter whea~ to bo mon~tored by sa~d maxlmllm capac1tance Cm defined between two ad3acent statlonary electrodes.

F1g. 4Q 1s the funct10nal d~egraln of an epperatus. a code generator. which ssnerates a digital code corraspond~ng ta the 1nd~cating numbsr of counter wheel bY maans for deterimin~ng the sat of sa~d stat10nery electrodes hav~ns sa~d max1mum capacltance Cm~

The coda generator compr1ses osclllator 212~ scanning counter ond latch 216 demultiPlexer 222. sens1ns dev~ce. multiplexar 224 and amPLifl0r 226. Wires ~0 of said sensing dev1c~ 1s connectad to demultiPlexer 222 end mult1plexer 224 bY connector 90. Scanning counter and latch 216. damultiplexer 222 and mult1plaxer 224 constitute a scann1ns dev1ce which ~s scann1ng aach tationerY slectrods for input and/or output s~gnals.

., , :

~3~3~

Tha contsnt of scann1ng counter ~nd latch 216 is the d1g1tal cod0 wh1ch is corresponding to -ths 1ndicat1ns numbsr of counter wheel 50 and 1s stored 1n the courter 216 by l~tching s1snal wh1ch w1~L be obtalned from the max~mum output s1snal ow1ns to S sa1d maxlmum capac1tance, Sa1d stat10nary electrodes. demult1Plexer 222. mult1plexer 224.
counter 216. and osc1llator 212 are connected to each other 1n such ~ manner that, while input sisnal is sequent1ally appl1sd to each of 10 st3t10nary el2ctrod~s, an output s~nsal 1s measured at 1 the stat10nary slectrode whose number is higher. by one. than th~t of the stat1onRry ~lectrode for the input s~gnal.

The s19n~l from osc1llator 212 1s appl1ed to one of 10 stationary electrodes of sa1d sensin~ dev1ce by demult1Plexer 222 whose channsl 1s salected bY counter 216. Mult1plexer 224 1s to obtaln the outPut slgnAl from the stat10nary ~lectrode whose number 1s h1sherl by one. than that of the stat10nary electrode to wh1ch an 1nput s1sna~ ~s app~1ed throush demult1plexer 222.

The output sisn~l from multiplexer 224 1s ampl1f1ed by amplif~r 226 so as to have enoush masnltude, and then appl1ed to lev~l detector 232. Level detector 232 d1st1ngu1shas the output s1gnal from amPl1f1er 226 corrsspand1ng to the angular Posit1on of sa1d rotary electrode 52 from others wh1ch can be cons~d~red as no1ses. The outPut s1~nal from l0vel det~ctor 232 1s used as a t1m1ng s1snHl to latch the content of counter 216. When 25theoutPUt s1sn~l 1s obtalned from lsvel det~ctor 232. the .,~,, :

:: : - : . :

.

~323~ 6 content ~f counter 216 is the b1narY code correspond~ng to the 1nd~cat1ns number nf countar wheel S0. Thsrefora. the code correspond~ng to the ansuLar pos1t10n of sald rotarY elsctrode 1s obtained in b~ncrY form bY latchlng the content of counter 21h by S tha output sl9nal obt~n~d from lev~l detector 232. The code can be dlsPlaysd on or transfsrred to a local fac~lltY for further Process .

F1g. 48 1s a tabl~ wh~ch repressnts the correspond1ng rslationshiP between sald code and the indlcatlng number of 1 countsr wheol by sst ot statlonarY electrodes bains selscted for 1nput and outPut signals. wh~ch ~s obtalned from F1g. 4~.

Thus. there is provid~d an capacltlvely reading apparatus.
a code generator. wh1ch can determlne the 1nd1catlng number of counter wheel. that is the an9ular posit10n of rotarY ob~ects.
without ma~lng mechanical contact with the rotary obiects.

f19. 4C shows a mod1f1~d block diagram of sa1d apparatus. in wh1ch mod-m counter 214 1s used between osclllator 212 and counter 216 1n order to apply an inPut signal cons1sting of several perlods to each stationarY ~lectrode of said sensing dsv1ce. Whenever each pulse ls appl1ed to countar 216 from counter 214. counter 216 sequentially selects each channel of demultiPlsxer 222 and multiplexer 224. Therefors. the number of perlods of the lnput slgnal appl1ed to each stat10nary slectrode through demultiplaxsr 222 ls m.

~ 3 ~

fis. 4D shows another modlfied apparatus. in wh~ch P~riod ssle~tor 234 ~s used for re~ect1ns the flrst and last per10ds of said output s1sna~ fr~m levsl detsctor 232. because the outPut s1snal from lsvsL detsctor 232 dur1ns those perlods can conta1n unwantod componsnts ~ntroducsd by sw~tch1ng op~ratlon of dsmultiplsxer 222 and mult~plexer 224. Per~od selector 234 1s to selsct the central perlods of th~ outPut s~snal of lov~l detsctor 232. Thsrefora. the rsllab1l~tY of sald apParatUs 1s ~mprovsd by uslns ths ~utput slsnal from p~r10d selector 234 as t1mins s1snal for latch1ns the cod~ 1n counter 21~.

Fls. '~E 1s anothar modif~ad appar~tus for s~neratlng carr~er s~gnal whose perlods are ~n correspond~ng relatlonshlP to each number asslgnad to sald stat10nary alecrodes. for gensr~t1ng a modulat~on s1sn~l correspond1ns to ths output s1snal from psriod sslector 234. and for ssnsratlns a modulated s19nal to be transmltted to a central facll1ty at A dlstance throush 2-w1re transm1ss~on l~ne.
The lensth of ons perlod of the 1nPut s~snal to countar 216 1s equal to tha tlm~ for sach stat~onarY electrode to bs connected to ths lnPut s1snal throush demultlpl~xer 222. that 1s. th~ t1ma for each code to be hsld 1n countar 216. The lnPut s1snal wavaform to countar 216 ls converted 1nto a s~nuso~dal wavaform by f1lter 242. aven though 1t could ba converted aftor modulatsd. Th1s s1nusoldal waveform from f1lter 2'~2 ls usad as a carr1er to transmlt sa1d code to a central fac1llty at a dlstAnce throush 2-w1rs tran~mlss10n l1nsO
.
-- ~ ?S

.
^~

~3~

Thus. th~rs 1s provid~d means for sensrat1ng a carr1er whose psr10d 1s corresPondlng to each ansular posltlon of sa1d rotarY
electrode. that 1s sach of the d1scrate angular Pos1t10ns of rotary obiects. 1s prov1dsd by the 1nvent10n.

The' output of psr10d sel~ctor 234 can b~ us~d as modulat10n s1snal. but 1t 1s f1rst converted lnto a s1nuso1dal wavsform bY f1Lter 244 and then 1s us~d as a modulat10n s1gnal.
Sa1d modulat10n s1snal is obta1nsd dur1ns ths per10d of sa1d c~rr~er wh1ch 1s corresponding to the 1nd1cat1ng number of countsr wh~sl.

Both sa1d carr1sr s1snal and sa1d modulation slsnal ara s1multan~oulY appL~ed to modulator 246. The Perlod of sa1d carr1er wh1ch 1s corrsspond1ns to thQ stationary ~lectrode from ,wh1ch sald modulatlon s1snal 1s obta1ned ls modulated wlth sa1d modulat10n sisnal. Ths modulated slsnal be~ns obta1ned from modulator 2~6 15 to be transmittad to a c~ntral fac1lity at a d1stancs throush 2-w1re transm1ss10n l1ne.
Thus. a modulated s1snal transmlttins the informat10n of th~
lnd;cat1ng number of counter whesl. ths ansular pos1tion of rotarY ob~ects. 1s easllY sqnerat~d accord1ng to ths lnvsnt10n.

When sa1d modulated s1gnal ,1s recsived at a central ; fac1l1ty, the 1nd1cat1ng number of counter wheel 1s rscoversd from the number of the per10d of sald carrier modulat2d with said modulat10n s19nal.

~6 , .
' . ' ' ' .

~l3~3~

As an example. ths 1ndlcatins number of counter whsel S0 1n F~s. 4E 1s as~umed to be 4. Th1s example shows how to convert ths 1nd~c~t1ng number 4 of count0r wheal S0 1nto the 5th per10d of carrl~r and then how to modulate the 5th par10d of carr1er. Bccause the lnd~cat1ng number of counter wheel S0 1s 4. the rotarY slectrod~ 52 is ln confrontlng relatlonship to two statlonary electrodes whose numbers are 3 and 4. as shown 1n F1s.
3E.

Typ~c~L waveforms observ2d at various Po~nts of the c~rcu1t of F1s. 4E are shown 1n F1ss. S~-SH.

F19. S~ shows the waveform of osc1llation slsnal. Flg. 5B
shows the output of counter 214 wh1ch 15 a mod-4 counter. The 1nput of counter 216 ls converted lnto s1nuso1dal waveform. as shown ~n Fls. SC! bY f1lt~r 242. Th1s sinusoldal waveform 1 used as tha carr10r for transm1ss~on. The number of the stot10nary electrode which ls ths lnd~cat1ng number of counter whesl is des1gnated below the Per~od of carrler which 1s oorrespond1ng to that number.

Flg. 5D shows the outPut waveform of ampl1fier 226. The s1snal durlng 5th per10d of sald carr1er 1s correspond1ns to 4 whlch 1s the 1nd1catlng number of countsr wheel 50. and the s19nal durlng the other Per1ods ~s due to no1se. Because count~r 214 1s a mod-4 counterq the output from ampllf1er 226 1s the s1gnal of only 4 per10ds.

Flg SE ls the output ~snal from level detector 232. wh1ch 1s the . .

.
-~323~ ~

s19nal for the lnd1catlng number of counter wheel 50 .

Flg. SF shows that both the f1rst and the last per1ods of the output s1gnal obtolned from level det~ctor 232 are reiscted by per10d selector 234. The output s19nal from perlod seLector 234 1s converted 1nto a s1nuso1dal waveform. as shown 1n F~s. S~.
by f1lter 244.

Both the carrisr of F1s. SC and the modulat~on s1gnal of F1g. SG
are appl1~d to modulator 246. Then the 5th per10d of sa1d carr1sr ~s modu~atsd w1th sa~d modulat1on s~snal. as shown 1n F1s. 5H. The wavsform of F1s. 5H can be transm1tted to a centr~l fac1lity thraugh ~--wirs transm1ssion l~ne.
, Thus. the modulat~d s1snal trunsm1tt1ns the 1nd1cat1ns number 4 of counter wheel 50 to a d1stance 1s generat2d by the capac1t1vely r~ading apparatus shown 1n F19. 4E.

When th1s modulated waveform 1s rPce1ved at a central fac1l1ty. the 1nd1cat1ns number 4 of counter wheel S0 1s easlly recovsred from the 5th psr10d of tha rece1ved waveform bY

hardware/software of a larse computer sYstem1 because the 5th per10d of carr10r can be easlly detected.

.
However. there may bs amb1suous situat10n 1n v1sually , .
:, ~

3 ~

read1ng the 1nd1cat1ns number of countsr wheel whsnever the 1nd~catins number of countar wheel of the next low f19ure 1s chang1ns from 9 to 0 The same situat1on can occur to th1s read1ng apParatus F19s 6A-6F show an 0xample of th1s s1tuat10n that the 1nd1cctln~
number of counter wheel SOa of h19h figurs 1s chang1ng ~rom 5 to 6 because thH 1nd1catlng number of the counter wheel SOb Df the next low f1sure 1s chanslng from 9 to 0 As shown in F1s. 6A rotarY alectrode 52 of countsr wheel SOa for high f~gure is in confrontins ral3tionshlp to three stationary electrodas whose numbers Ara ~ S. and 6 resPect1vely.

Fig. 6B 1s an electr1cal capacitor model for F1s 6~
C1 1s the capac1tnnce bctween ths stat10nary elactrode of number 4 and rotary electrode 52 and C2 1s the capac1tance between the stationarY e~ectrode of number 6 and rotary elactrode 52 The capac1tance between tha stationary electrode of numbar S and rot~ry 0lectrode 52 h~s tha max~mum v~ua Cmax C is the angls dafinsd 1n F1g. 6~
Then C1 and C2 are def~nad ~s follows:
.
; 20 C1 = Cmax X C 1 ~ --)]

C2 = Cmsx X (-----) Cl and Ch das19nated 1n Fls. 6C are the equ~valent ` 29 . .
: . - . . ~

~23~

capacitances to the capac~tor model of F1s. 6B. resPect1vsLY.
CL ~s the caPoc~tance between the stat10nary slsctrods of number 4 ~nd th~ stot~onarY electrode of number 5. Ch 1s the capac~tance batwe~n tha stat~onary electrode of number 5 and the stat~onary eLectrnde of number 6. Then Cl and Ch ~r~ deflncd as follows:

Cl = 1 / C l/Cl + l/Cmax = Cmax X Cl -72 - ~

Ch = 1 / C l/C2 ~ l/Cmax ]

= Cmax X ~ 1 - (-----~---)]

~hen C becomes 1~ degrees. than Cmax Cl ~ Ch = ---------2 Cm Thsrefore. the roference level of sa1d level detsctor 232 1s ~5 salected to be 3ust below the output leval beins obta1ned from ~mp~1f1er 22~ when C ls 18 desrees. Then. th~ modulat10n s~gnal ls obtalnad from bandpass fllter 24~ for two Per1ods o~
carr~er. ths 6th and 7th per~ods. as shown ~n fis. 6E.

. .
'~

' ',' .

' ~

/ `^`,~

~t~23~

Fig.6D 1s the carr1er. the same as that of F1s. SC. F1s. 6F 1s the modulated output w~veform obt~1ned from modulator 246 accord1ng to ths modulat10n waveform of F1g. 6E.

Thus. when the 1nd1catins number of counter whsel 1s chang1n~ from ons number to tha nsxt number. the carrier 1s modulated for two per1ads correspond1ng to those two 1nd1cat1ng numbers. rsspectl1velY. by the two modulat10n s1snQls.

Howsv~r. the corre~t 1nd1cat1ns number of countsr whsal can be rscovarsd from the two moduLated per10ds of the carr1ar when tha modulated waveform 1s rscs1ved at a central fac1l1ty.
Whan ths waveform of F79. 6F ;s recs~ved at a csntral fac1l~ty.
the correct 1nd1c~t1ng number of count~r wheel can be recovsred from tha modu~atsd per10ds o~ the rece~ved waveform.

If thc ~nd1cat1ng number of counter wheel SOb of the low f~sure has alreadY been determ1ned to be 9 at the central fac1l1ty. thc numbsr for the h19h f1sure must be detsrm1ned to b~ low numbar by the f1rst modulated p~r10d of ths reca1vsd wavaforml to b~ number S by ths 6th per10d for th1s cas~.
, .
On ths contrary. 1f ths number for ths low f1gure has alr~cdy 20 bsen determ1ned to b3 O. the numb~r for the h19h f1sure must b~
detsrm1ned to be~ the h1sh number. 1nstead of the low number. by th~ second modulated Por1od of th~ rscs1ved wav~form. to be number 6 1nste~d of number 5 by the 7th per10d for th1s cass.

.
. , , ~

. . ..
.. . .

~32~

The correct decis1en on the ~mbisuous s1tu~tlon describod ~bovs can be made by said app~ratus. but the situation 1s transmltted to a central ~ac1L1ty by the modulat10n method descr1bed abova.
By do1ng so. the capacltively read1ng apparatus can be prov1ded at a very low pr1c~.

The resolution of the capacltively rsadlng aPparatUS of F1ss. 4~-4E 1s PrimarilY dependent upon the numb~r of said stationary electrodes and thP resolut10n of sald level det~ctor.

However. th~ resolutiorl of sald capacit1vely reading 10 apparatus can b~ lmProved bY using ~/D convert~r ~n order to detect ths level of the output signal obtained from said ampl1f1sr.

F19. 7 shows another modif1~d apparatus uslng averager 612.
A/D convertsr 614. and microcomputar 616.

Avarager 612 convarts thc outPut s1snal from ampllf1er 226 1nto DC level sl~nal. The DC lsvel slgnal from averager 612 1s appl1sd to A/D converter 614 so as to bs convertsd 1nto B-bit blnary number. Thers are 10 B-bit binarY numbars corresPondlng to 10 discrete ansular pos1tlon of said rotarY alectrode 52.
Ths maximum value among 10 8-b1t binary numbers can be determinad bY a comparator device. but microcomputer 616 is used for implement1ng the process in th1s embodiment.

, ; .~ . --' .. ..
, ~. ' . . .
d : `
,: :
. .

~ 3 2 ~

Microcomputer 616 sets the cods in counter 216 1n oder to select ~ ohannel of demult1plexer 222 f~r input s;gnal and a channel of mult1plexer 224 for output sisnal. and reads the output from ~/D
oonverter 614 at the center of eaoh per10d of sa1d carrlsr.
In other words. microcomPuter 616 reads 10 output numbers from Q~D converter ~14 correspond1ng to each oF sa1d stat10nary electrodes. Then. microcomPuter 616 determines the number of the stat~onarY eLectrode corresPonding to the indlcat1ng number of counter whael by evaluat;ng the maxlmum value.

In order to improve the reliabiLity- microcomPUter 616 maY read the output from ~/D converter several times dur1ng each Period of sH1d carrier. calculate the mean value for each of 10 per10ds of said carr1er. determine the max;mum value amons 10 mean values. and then determ;na the content of counter 216 corr~spond1ng to said maxlmum value. Sald content of counter 216 ~s iust equal to the 1nd1cating number of counter wheel to bs mon1tored.

If ths max1mum value of the output s1snal from avsragsr 612 is obta1nsd at Cm (Cmax/2~ and ls adiusted to be equal to the maximum dYnam1c rhnge for the 1nput of 8-bit Q/D converter 614.
then the resolut~on be~ng obta1ned from the c1rcu1t of F;s. 7 1s approx1mately evaluated as follow~ng:

resolut10n = 360/10/2~8 = 0.1~ degree/bit ' ' . ' :
.' "
.

1323~

Thls h1sh resolution of ths capacltlvely raading appsratus shown ~n F~g. 7 wlll be superlor to ~nY othsr apparatus be1ng manufactured at the same Pr~ce.

Thus. there ls Provlded a capacltlvely read1ng apparatus hav1ns a relat1velY hlgh resolutlon of the angular posltlon G~
rotary ob~ects bY uslng A/D converter to measure the output signal obta1ned from sald amplifler.

Mlcrocomputer 616 can be used for generating a FSK or other modulated signal to be transmltted to a distance throush 2-w;re transmission llne. as well as for determ1nlng the ~ndicating numbsr of counter wheel from the number of stat~onary electrode hav1ng the max1mum output signal.

Th~ m1crocomPuter-b~sed configurat~on of Fig. 7 can also prov1de manY other advantageous functions such as real time data collert~on. ~ demand meter~ng. dsmand l1m~tlng. t1me-of-wse meterlng. psa~ alert. PrePald meterlng. standard modem slgnal ~enerhtlon. etc.. by 1ts software.

There ls Provlded another preferred feature of the presant lnvent~on by connect~ng sa;d statlonary electrodes to each other ln part1cular mod~. By dolng so. the number of connecting w;res from sald statlonary electrodes to sa;d demult1plexer and/or mult1plsxer 1s sreatlY redu ed and the number of ohannels of sa1d demultlplexer and/or multlplexer ;s fllSO greatlY reduced.

: 34 .
~ : . . - . . . .
.

- . . ~

':
.

~3~3~6 F1g. 8 shows a Plan v;ew of the exempLary connect;on 1n a capacitively sensing device. In this connection. every other stationary electrode ls dssignated by A. B/ C. D. and E, respectively. ln the cloc~-w1se direction. Fach of these five stationarY ~lectrodes is connected to evsrY two other st~t~onary slectrode. resPect1velY. 1n the cloc~-wlse direct10n.
Therefora. the sens;ns dev;ce of this smbod1msnt is connected to sai~ cDde generator bY onlY 5 w;res.
In other words. 10 stationary elsctrodes of said sens;ng dev1ce ~re scanned by said code generator through 5 wires instead of 10.

Fis.9~ shows a mod1f1ed apparatus accompany1ng sald senslng dev1ce shDwn in Fig. 8. The structure and operation of said apparatus 1s the sams as thMt of Fig. 7 axcept the reduced number of channels of demultiplexer 222 and of mult~plexer 224.
~ccording to this connecting mode. the number of wires for scannlng 10 stat~onary electrodes is reduced to a half of the number of stationary slectrodes. However. the nurnber of channels of mult1plexer 222 and of multiplexer 224 is 4. less than a halF of that for the sensins device of F~s. 2F.

This is an excellent merit for developing the circuit as a single chip. Fig. 10 shows the corresponding relationship between the cods gsnsratsd bY counter 216 and ths ~ndicating numbsr of counter wheel 50. wh1ch is obtained from the circuit of Fig. 9.
Wh1le ths sequsnce of the lndicating numbsr of counter wheel is presented in natural order in the sensing device of Fig. 2. the sequence -for the sensing device of F1s. 8 is mixed up. as shown ~3239~L~

in Fig. 10. Therefore. the order of th& per10d of carrler be1ns modulated with the modulation signal does not follow to thæ
naturnl order. However- as shown in Fig. 10. each numbær of count~r 216 1s uniquely corrsspondins to the set of stationarY
electrodss wh1ch are 1n confrontirlg relat10n6hip to rotary electrode 52. and each set of said stat10nury electrodes ;s un~qusly corresPondins to æach ;ndicat1n~ numbcr of counter wheel 50. On the other hand. the apParatus of F1s. 9 transforms the 1nput waveform of counter 216 1nto a sinusoidal carrier whose period ls un1quelY correspondlng to each number of counter 216.

Figs. llA-llE are typical output waveforms beins obta1ned from the circu1t of F19. 9 whæn the ind1catins number of counter whesl 50 1s 4.

F~g. 11A ls th~ w~veform showing the corresponding relationshiP
betwesn each Per10d of said carrier and each set of stat;onary eleotrodes wh1ch are se~ected for input and output s19nals during thæ corrssPord1ng pæriod.

In th1s example. the output s1snal from amplifier 226 is obta1ned durins the second per1Dd of carr;er. as shown in F19.
11B. because tho output signal ;s presented at stat10r,ary electrode of B onlY when an input s1snal 1s appl1ed to thæ
stat10nary electrode of A. as shown in Fig. 10.
Whæn the carrier s1snal of Fig. llA and the modulat~on sisnal of Fig. 11B are s~multaneously applied to modulator 2461 the ' ~32~

modul~ted outpwt s1gnal shown in F1g. llC 1s obta;ned so as to be transmltted to a d1stance through 2-wire transm1sslon line.

In the clrcult of F1g. 9. four per10ds of carr1er may be modulAted whan the ansular posit10n of countsr wheel 50 is in the trans1t10n from one number to the next. In th1s case. sa;d rotarY elPctrod~ ls in confront1ns relat10nsh1P to three stat10nary electrodes.

F1s. 11D shows the modulat10n waveform obtalned from ths c1rcu1t of F1g.9 when the lnd1cat;ng number of countar wheel 50 is chang1ns from 6 to 7. The f1rst two modulat10n waveforms ars obta;ned whenever an output sisnal 1s measured at the statlonary electrode of D, and the second two modulat10n waveforms are obta1nad when an input ;s aPPlied to the stationary elactrode of B. Th~ carrl~r of F1g. 11~ and the modulation s19nal of F;g.
15 llD are aPPl1ed so as to obta1n the modulated wavaform. as shown ln Flg. llE. wh1ch can be transm1tted to a d1stance throush 2-w1re transmlss10n line.

Howaver. the modulated s1gnals of F1g. llC and F1s. llE. wh1ch are obta1ned from the c1rcu1t of F1g. 9. can be used for transmltt1ng the ;nformat;on of the 1ndicating number of counter wheel to A d1stance through 2-wire transm1sslon l1ne.

Ths correct 1ndicflting number of a counter wheel can b~ recovarsd from the modulated waveform shown in Fig. llC or 1n F1s. l1E when the waveform 1s rece1ved at a central facil1ty at a distance.

. ~
,.

~ . .
- . . . .

~32393.~

Thus. there 1~ Prov;ded the simpl1f1ed ~dr ~sner~tor bY
by means for 1nterconnect1ng sa1d stat10nary electrodes sach other 1n a particular mDda.

There 1s prov1ded another praferred fenture of the 1nvent10n whlch has the ~ff~ct1voly lncreased maximum capacitanca bY means for connect1n~ s~id rotary electrode to sa1d code sen0rator.

On0 approach to connect sa;d rotary electrnde 52 to said c1rcu1t 1s to mQke both female 54 and mals 56 of the counter wheel 50 conductive mater;al.

F19. 12A and 12B show the plan v1ew and the s1da view of sa1d sens1ns dev;ce. respact;valy. In this examPle. female 54 is f1xed to counter wheel S0. as shown 1n F1s. 128.

Rotary clactrods 52 1s 1n confronting ralnt10rlsh1p to onlY two stat10n~ry sl~ctrodes for this exemPlarY embod1ment. but the rotary electrod~ 52 m~y ba constructsd to be 1n confront1ng ralat10nsh1p to ane or more than two stat10nary al~ctrodos accord1ng to ~ dss~rad sensitiv1ty.

Th0 conduct~vs female 54 is connected to rotarY electrode S2 and the conduct1vs m~lr 56 has a wire 58 to be connected to elactronic clrcuit. The conductlve female 54 is m~de so as to fr1ct10nlessly rctate on the conduct~va mala 56. Therefore there exlsts an electr1cally complete contact between the rotary elactrode 52 and the w1ra 58 through the female 54 and the m~le 56. F1g. 13Q 1s the slectricallY equiv~lent circu1t model 3~

. .
- ~ ~
:, . ~ :

~ ~23~

of said ssns1ns device for that case. ~n which sa~d sensing dsv~ce is represented by two cRpacitnrs having said maximum capac1tance Cmax defined between wlre 58 and ths statlonary sl~ctrod~s wh1ch ars 1n confront1ng ralationshiP to rotarY
sl~ctrods 52.

However. as a worst case. a complets contact between ths conduct1ve famaLe 54 and ths conductive male 56 may not ~x1st.
Then. the conductive female 54 and the conductive male 56 can be considsred as a coax1Ql capacitor. as shown 1n Fig. 13B.

Thc capacitance Cco of sa;d coax~al capac~tor is defined as following:

C c o ~
Log(1/a) - Log(1/b) . where K is a proPort~onal constant. a is the r~dius of the conductlv~ male 56 and b is ths radius of the fsmale 54.

~ecause the rcd~us of the female 54 is nearly equa~ to the rad~us of the m~le 56. Cco maY be considered ~s inf1n~ty when compared to Cmax. Thus. ths elsctrlcally equ1valent c1rcu~t shown 1n Fig. 13A ~s a~so aPplied to ths worst case.
This means that the conductlve female 54 always makes an 2 electr~cally complete connectlon with the conductive mals 56 and the sens1ng devlce shown in Fig. 12A can b~ rePresentPd by the ~quivalent circu;t of Fig. 13A.

" .

- : :
'' ~
,~;
, ~, .
, ,:

~3~,39~6 Two statlon~ry slectrodes are in confrontlng reLAtlonshiP to sa~d rotary olectrode for th~s exemplary embod~msnt of F1g. 12~.
Therefore. in order to connect sa~d two maximum caPacitances ln parallel. sa~d stat10nary electrodes hava to be scanned in such à
manner th~t tw~ adiacent st~tlonary electrodes ure always connected to fln 1nput or output termlnal.

Then. the lnput s~snal of sa;d sens1ns dev1ce can be trsnsm;tted to the max1mum output of said sensing dev1ce through the capacltance 2Cmnx. Therefore. the max1mum magn~tude of the output signal of the sensing device of F1g.12~ ;s expected to be four t~mes that of F;g. 2F ~n wh1ch an lnput siganl ls transm;tted to the outPut of the sens~ng dev;ce through the cnpac1tance Cm ( = Cmax/2).

This msans that sald sensing device shown in F~g. 12~ can accompany more slmPlif1ed apparatus or can be made in much smaller slza th~n ths sens~ng dev~ce of F;g. 2 under tha same condlt10ns for said electronic circuit.

Thus. means for prov1ding a smaller senslns device is provlded bY méans for constructing two conductors hav;ng an electrlcally comPlete contact between them. of whlch one conductor is connscted to said rotary electrode and the othbr conductor ~s connected to the e~ectron1s circult accomPanY1ng said sens~ng dev1ce.

Fls. 14~ shows the apparatus accompanylng sa;d eenslns devlce of F1s. 12A. In th1s embodiment. an input s~gnal ;5 - - -, ~
: -, - , . .
.
,~ . . . . .

1323~

simultaneously aPpl1ed to two ad~acent stationary sLactrodes by conrect~n~ the outPut tHrm1nal of multiPlexar 224. wh1ch is used os the output tarm~nal ln Fig. 4A. to the 1nput term1nal of demultiplexar 222. Output s1gnal is measured from wire 58 connectsd to sa1d mcle 56 wh1ch 1s coupled to sa1d rotarY
electrode 52 through female 54. The opsrat10n of sa1d apparatus of F1s.14A 1s th~ same as that of F1s. ~Q. excePt tha modif1~d scann1ng dsvice.

Fig. 14B 1s tha corresponding relationsh1p b~tween said code ssnsrated by sa1d app~ratus and th~ indicating number of counter wheel to be mon1tored by sa1d maximum capac~t~nc~ 2Cmax. Th;s is the same as that of FIg. 4B.

There 1s prov1ded another Pr~fsrred feature of the 1nvent10n by conn~cting sa1d stationary electrodes of sa1d sens1ng dev1ce shown 1n F19. 12A to sach other ;n a Part1cular mode. Sa1d connecting mude 1s the same as that of fig. 8.

F1s. 15A and 15B show th~ plan v;ew and the s1de v1ew of the exemplary connect10n mode. respect1vely.

F1s. 16A 1s another mod1f;ed apparatus accompany1ng said senslng dsv1ca. In order to s1multaneouslY apply an input sisnal to each set Df two stat1onarY electrodes to be 1n confronting relationsh1p to sa1d rotary electrode. the output t~rm1nal of ~` muLtiplexar 224 ~s connacted to the lnPut tsrm1nal of ` dcmult1plsxer 222. The output signal is m0asur~d from w1re 58 , , , .

~23~

of sald sens1ng dev1ce.

F19. 16B shows the corrasponding relat10nship b~tween sach set of two stat10nary ~lsctrodes and ~ach 1nd1cat1ng numb0r of counter wheal to bQ mon1tor~d. which 1s the same as that of Fig. 10.
S Theref~re. the nparation of s~id flpparatus of Fig. 16~ 1s also th~ snma as th~t of F~g. 9.

In the aPparatuses descr1bsd above. cn 1nput s;gnal 1s appll~d to the st~t10narY elsctrodes and an outPut s1gnal 1s measured from w1rs 58 connscted to sa1d male conductor.
10Howsver. ths 1nput s1snal can be appl1ed to w1re 58 and the output s19nal can bP measured by scann1ng said stat10nary eLsctrodes. Its operat10n ~s also descrlbed in the same way as the above.

-In order for all ths circu1t presented 1n th1s lS documentnt10n to b~ us~d for remotalY read1ng the number of multipls f~gures of utilitY meter. another demult1plexer for input s1snal and/or another mult1plexer for output s1snal maY bs used 1n ths code generator.

The read1ng apparatuses accordin~ to the present 1nvent10n do not n0ed s DC power supplY except only wh~n thsr~ is a nsed to rs~d the 1ndicat10n of meters~ bacause sa1d apparatuses can be wsed together w1th convsnt10nal ut~l1ty meters by keeP1ng the mechan1cal ind1cat1ng structure of the meters. ~ecause the power consumpt~on of tha aPparatUs 1s small 1n a short time. the DC power can be suppl1ed from a central facllity to said ~2 - .

..

~' ~ ' , .

132391 ~

~pparatuses through 2-w1re transm1sslon l1ne. Therefore. said apparatuses flre connscted to the 2-w~re trflnsm;ss10n line through power-llne interface circuit. Power-line 1nterf~ce c1rru~t maY cons1st of resonant c1rcult and on/off sw1tch. When there 5 ls c need to read ~n Utll1tY meter w1th th1s apparfltus. ~n 1nterogatlon slgnal together w1th DC Power 1s sent from central fac1l1ty to the meter throush 2-wlre transm1ss10n l1ne.
The 1nterogation signal 1s detected by the filt~r1ng operat10n of pow2r l~n~ 1nterface c1rcuit and causes a magnet~c relay or el~ctron~c sw1tch to bs turned on ~n order for the DC power to be suppl~sd to th~ meter.
The transm~ss;on l;ns ~s used to collect the meter reQd1ngs as well flS to supPly the interogat~on signal and DC power to th2 meter to be monitored.

WhiLe thers have been descr1bed what ~rs beli~ved to be the - Preferred embod1ments of the Present 1nvent10n. those s~1lled 1n the art w1ll recosn1~e that various changes flnd mod1f1cat~ons maY
be made thereto w1thout dspartlng from ths ~rinciples of the invent~on. and lt 1s 1ntend2d to claim all such embodiments as fall w1thin the tru scoPe thereof.

q3 : . .
: ` :
`
'' .

Claims (7)

1. A capacitive reading apparatus for remotely reading the angular position, speed and/or direction of rotation of a rotary member as it rotates about an axis of rotation and defines a circumferential path comprising:
(a) means for arranging a rotary electrode on a surface of said rotary member to be monitored;
(b) means for arranging an array of stationary electrodes on a surface of a stationary member whose surface is positioned in a confronting relationship to said circumferential path so that capacitance is defined between each of said stationary electrodes and said rotary electrode, a plurality of said stationary electrodes being in a confronting relationship to said rotary electrode according to the angular position of said rotary electrode, have dominant capacitance;
(c) means for being connected to said electrodes to apply an input signal to said capacitance and measure an output signal which is in proportion to said capacitance;
(d) means for generating codes, each of which is corresponding to each angular position of said rotary member, while applying said input signal to said capacitance and measuring the output signal owing to said capacitance;
(e) means for latching the codes corresponding to the angular position of said rotary electrode by a maximum output signal owing to said dominant capacitance; and (f) means for transmitting said codes to one of a local facility for display and a central facility at a distance for further processing, wherein said applying means includes means for insuring said output signal obtained during one of said codes persists for several periods, and further comprising means for selecting the central periods of said output signal.

2. A capacitive reading apparatus for remotely reading the angular position, speed and/or direction of rotation of a rotary member as it rotates about an axis of rotation and defines a circumferential path comprising:
(a) means for arranging a rotary electrode on a surface of said rotary member to be monitored;
(b) means for arranging an array of stationary electrodes on a surface of a stationary member whose surface is positioned in a confronting relationship to said circumferential path so that capacitance is defined between each of said stationary electrodes and said rotary electrode, and a plurality of said stationary electrodes, being in a confronting relationship to said rotary electrode according to the angular position of said rotary electrode, have dominant capacitance;
(c) means for being connected to said electrodes to apply an input signal to said capacitance and measure an output signal which is in proportion to said capacitance;
(d) means for generating codes, each of which is corresponding to each angular position to said rotary member, while applying said input signal to said capacitance and measuring the output signal owing to said capacitance;
(e) means for latching the codes corresponding to the angular position of said rotary electrode by a maximum output signal owing to said dominant capacitance; and (f) means for transmitting said codes to one of a local facility for display and a central facility at a distance for further processing wherein said transmitting means is achieved by modulating a carrier, which is the input waveform of a counter which is used to scan said stationary electrodes, with a modulation signal which is said maximum output signal.

3. An apparatus according to claim 2, wherein said carrier is converted into a sinusoidal waveform by a filtering function and said modulation signal is converted into a sinusoidal waveform by filtering function.

4. An apparatus according to claim 2, wherein said sinusoidal waveforms are obtained by integrating functions.

5. A capacitive sensing device for remotely monitoring the angular position, speed and/or direction of rotation of a rotary member as it rotates about an axis of rotation and defines a circumferential path comprising:
an array of N identical stationary electrodes substantially arranged on equally divided N areas on a surface of a stationary member which is positioned in parallel to said circumferential path, where N is an integer;
a rotary electrode substantially arranged on a surface of the rotary member in such a manner that said rotary electrode is asymmetrical about an axis of rotation and is in confronting relationship to M stationary electrodes among said N stationary electrodes, where M is an integer greater than one and less than N;
means for applying one analog input signal simultaneously to M capacitors defined between said M
stationary electrodes and said rotary electrode, where each capacitor has a maximum capacitance defined by the area of a stationary electrode; and means for measuring an output signal whose magnitude is in proportion to said maximum capacitance;
wherein said applying means comprises means for connecting said input signal simultaneously to K stationary electrodes among said M stationary electrodes, where K is an integer less than M; and said measuring means comprises means for connecting an amplifier simultaneously to the remaining M-K stationary electrodes among said M stationary electrodes in such a manner that said amplifier provides a maximum analog output signal which is responsive to the sum of capacitively induced signals in said M-K stationary electrodes.

6. A sensing device according to claim 5, wherein N is 10;
M is 2;
said input signal is connected to one of said 2 stationary electrodes which are in confronting relationship to said rotary electrode; and said amplifier is connected to the other of said 2 stationary electrodes.

7. A sensing device according to claim 6, wherein each of 5 alternate stationary electrodes among said 10 stationary electrodes is connected to the third stationary electrode from that stationary electrode, respectively, in the same direction;
said rotary electrode is in confronting relationship to 2 stationary electrodes which are next to each other;
said input signal is connected to one of said 2 stationary electrodes through one of said 5 stationary electrodes; and said amplifier is connected to the other stationary electrode of said 2 stationary electrodes through one of the remaining 4 stationary electrodes except the one connected to said input signal among said 5 stationary electrodes.