CA1052923A - Telephone pushbutton dial assembly - Google Patents

Abstract

ABSTRACT
There is disclosed herein an improved dial assembly suitably adapted to provide an expanded capability for a TOUCH-TONE telephone system or to replace existing rotary dial assemblies in various equipment manufacturers' subsets with a TOUCH-TONE
like assembly. In particular the improved dial assembly includes an upper frame and a pushbutton arrangement similar to known TOUCH-TONE dial assemblies. Longitudinal and transverse rods positioned in separate planes immediately below the upper frame convert the downward movement of a particular depressed button into rotational movement. The rotational movement of the rods is utilized by suitably positioned cooperating sets of switches to connect in the necessary manner the various telephone circuits within and/or external to the particular subset. The improved dial assembly above expands the capability of present day assemblies in that it enables the provisioning of ancillary telephones functions, such as repertory dialing, toll restricting circuitry, etc., by the inclusion of an additional plane of switching. This is effected through the incorporation of a "third plane" switching board which contains a plurality of switches which open and close in response to the cooperative action between switches on this "third plane" board and an axial appendage extending downward from each of the buttons. This additional switching capability, together with the utilization of improvements in micro miniturization of electronic circuits, particularly large scale integration (LSI), results in a dial assembly which enables these additional functions to be packaged in the telephone subset itself.

Description

lQS'~923 This invention pertains to improvements in telephone dial assemblies, and particularly to improvements in the so-called TOUCH-TONE type dial assembly.
The TOUCH-TONE style telephone call transmitter is ~ -^
enjoying increased favorable acceptance by telephone subscribers.
Call transmitters employing TOUCH-TONE principles are described in numerous patents including United States Patent Nos. 3,109,071, ~ -Clifford et al., issued October 1963; 3,123,676, Prescott et al., issued March 1964; 3,274,345, Ham et al., issuel September 1966; 3,316,357, Ham et al., issued April 1967; and 3,479,470, Ham et al., issued Nbvember 1969; -- the latter two being based on divisional applications of the '345 patent. The basic principles of operation of the standard TOUCH-TONE unit are set out in the '345 patent at Column I, line 32 through Column II, line 5.
Many of the advantages of the pushbutton type dial assembly are pointed out in United States Patent No. 3,076,059, Meacham et al., issued January 1963. An advantage of particular note with regard to the TOUCH-TONE assembly is the fact that it provides more efficient use of transmission facilities with the reduction of calling time, as compared with a standard rotary dial, by approximately one-half. The latter attribute is extremely attractive since a material saving in telephone central office common equipment is possible.
A psychological feature of the TOUCH-TONE assembly, in this day and age when everyone appears to be in a hurry, is the relative rapidity compared with the rotary dial system with `
which one can place a call.
Because of this psychological advantage enjoyed by the TOUCH-TONE concept, if it were possible to convert the standard rotary dial systems to the TOUCH-TONE dial configuration the enhanced marketability of such an item would appear to be significant. The idea would be to remove the present assembly,

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~S'~9Z3 i.e., the rotary dlal assembly, ~rom the standard telephone ~ubset and to place thereln a TOUCH-TONE llke assembly whlch p~ychologically speaking appeals to the subscribor ln the same manner as an actual TOUCH-TONE assembly. Of course, from an operational point of view a converslon must take place, profer-ably within the TOUCH-TONE llke assembly whlch replaces the rotary dial aE~embly. This converslon herel~after ro~-rred to as outpulsing, permlts push-button dlaling with a ~ultable loop-disconnect output compatlble to the rotary dial output as 1B well known to tho~e in the telephone art. ~ecause o~ the difference ln the dlal times associated with the TOUCH-TONE
dlal and the rotary dial system, lt 18 apparent-that a memory device would have to be provided which would store the number as it i8 dialed and then feed it to the telephone transmlssion lines in the proper sequence and pulse form.
Given the increased subscriber acceptance of the touch-tone arrQngement for teleph~ne subsets, lt iB recognized that by lncreasing the anclllary functions that a telephone provides, a telephone equipment supplier ca~ ~urther enhance the marketability of hls product. mese anclllary runctions might include a repertory dlal ~unction whlch can provide elec-tron~c storage of up to ten frequently called numbers Or 12 or 16 dl~its each, all of whlch can be stored, erased or changed by simple keylng means employing the telephone buttons. Thls enables the subset operator to select a partlcular stored number through propor keylng leaving the tran~mitter ltself to "place"
that number onee lt is identlfied by the subJect operator.
An additional function whlch can be lncluded wlthln the anclllary ~unctlon area i8 the so-called "Toll Restrictor"
function. Generally, thls function 18 pro~ided, typically, in ~OS'~923 ~ ~

buslness of~ice exchange systems where it 18 desirable to pre~ent the dlallng o~ area code calls from all b~t a rew selected subset~ It doe~ thls by recognlzlng that an area code call 18 being dialed, as opposed to the rirst throe numbers of a local exchange. When lt detects thls occurrence the toll re~trlctor circultry is de d gned to cut off tho cor-responding subset connection - thu~ lnterrupting the call.
Also, functions not directly rolatod to the telephone art but wh~ch provlde subscriber convenience such as an elec-tronic calculator, are deslrable additions.
Until now, the outpulslng function and the variousanclllary iunctlons where desired had to be packaged external to a particular telephone subset. m e additional packaging costs and logistic problems ortentimes offset the advantages to bo galned thoreby such that tho ~quipment manuracturer would not contemplate even providing these functlons or, lr he did, le88 than enthusiastic customer acceptance was found due to "exc~-sive" cost.
Recent developments in the art Or electronic circuit fabrication, particula~ly microminiaturization and mo~e par-ticularly large scale integration (LSI), havo àdded a new dimen~.
slon to electronic circuit packaglng generally. Particularly, it has enabled telephone packaging engineers and designers to contemplate unlque packaging techniques whereby the outpulsing and ancillary functions could be provided in a manner where the logistic's problems and cast to the subscriber would be kept at a minimum.
It i~ a primary obJect of this invention to provi~e a dial a~embly havlng a TOUCH-TONE like dial faco whlch 1~ ex-30 pan~d to include additional anclllary functions heretofore ~--.. . .

1~5;~923 packaged separate to the ba~lc telephone sub~et.
It is another ob~ect Or thls invention to pro~ide a TOUCH-TONE telephone dial assembly whlch can provide certain ancillary runctions and do 80 wlthln the volume outllne Or pre~ent dlal a~emblles.
It is yet another ob~ect of thi~ lnventlon to provlde a TOUCH-TONE llke dial assembly whlch can be readlly ~ubstituted for the standard rotary dial assombly wlthout any modlilcatlon to standard telephone subsets.
It 18 stlll another obJect of thls lnventlon tp pro-vlde a TOUCH-TONE llke dlal assembly whlch lnclude~ means for providing a plurallty o~ untlng conrlguratlons whlch enable the baslc assembly to be utillzed in a varlety of subset con-figurations.
It iB another obJoct of thl~ lnvention to provlde an additional plane of switchlng within a telephone ~ubset whlch expands the potontial of heretorore standard ~ystems.
It 18 a further ob~ect of the invention to utlllze the latest advances in microcircult development, including LSI
development , with or without the third plane of swltchlng, to exp~nd the number and type of anclllary ~unctions whlch can be provlded withln a subset.
The presont lnventlon f~r an lmproved TOUCH-TONE
like dial assembl~ rather lncludes in addition to the standard upper ~r~me wherein there is located a plurality of pushbuttons in three columns-and four rows ln accordance wlth the standard dial face arrangement, a flrst and seeond plane of longltudinal and transverse rods respectively whlch are rotalned in appro-prlate notches cut out in an appendAge which 1~ mounted to tho upper frame. Each of the longitudinal and transverso rods .

~ 0 5~ 9Z~3 includes a plurality of appendagcs which are trans~erse to the axis of their respective rod and whlch are located along the length o~ the rod at posltlons corresponding to the partlcular location of one of the pushbuttons. ~hese first set Or appen-dages cooperate W th a ~houlder on lts corresp~nding buttonto convert the downward mo~ement o~ that button to rotational movement o~ the associated rod. Additlon~lly, ther- are two other sets of appendages trans~erse to oach Or the rods which, respectively, cooperate with first and second sets of swltches On the one hand the first set of the appendages cooperatcs, directly, with the first set Or switches to open and close the contacts associated with a swltch ldentlfied with a glven rod.
The second set Or appendages cooperates with a slidc actuator ~ bar located in a slot whlch i8 bound in a switching board positioned below the guide plate -upper frame assembly. The second set Or appendages cooperate with the slide actuator bar to cause a llnear movement Or the actuator bar. The actuator b~r furthor includes a set of appendagos which e~tend below the switching board and which CaUse a second set o~ switches to open or close whene~er any of the pushbuttons are depressed The rlr~t and second plane arrangement of longitudinal and tran~rse rods descrlbed above provides an economy in pack~
agln~ with re~ard to the implementation of the swltching func-tlon perfo d by the ~ir~t and second set of ~witches. With thls economy and with the packaglng o~ a standard TOUCH-TONE
oscillator clrcuit on a board lmmedlately below the switching board Ju~t identiiled, still yet another board employing large scale integratlon technique~ can be plggybac~ed onto the TOUCH- ~;
TONE oscillator board thereby providlng addltional ancillary functions such as repertory dialin~, toll restrictor, instant ~. " ' "

~ C~5'~923 number recall, and othera.
In the prererred embodlment the board immediatoly below the swltchlng board containing the sllde actuator bar i6 modified to provide an addltional ~witchlng plahe (third ~lane).
In this configuration, the addltional ewitching ~unctlon i~
performed by a plurality of leaf-spring swltches secured to the board and cooperating with an axially extendlng, hollow pro-Jection at the bottom of each of the pushbuttons. Nested within the hollow opening in thls appendage 18 a plunger and coll sprlng arrangement whlch on the one hand transmits the downward movement oi a glven button 80 that a given contact provlded by the leaf-sprlng swltch i8 open~d ln responso thereto. On the other hand, the coll ~pring provides the necessary re~lsting force to return the pushbutton to lts at-rest position. This ~5 additional switching capablllty can be employed to provide additional ancillary functions as well as enable packaging of the outpu~sing functlon within the outline of the dial assembly facilitatlng replacement of the~standard rotary dial assembly wlth a TOUCH-TONE like assembly. The ancillary functions and the outpulsing fun¢tion are pre~erably contained in an LSI
electronic a~sembly board which can be piggybacked to tho board containing the third plane of switchlng.
The upper frame is adapted to receive a wlde as~ort-ment of mDuntlng brackets whlch expand the versatlllty of the overall dlal assembly by enabllng it to be in~erted in a coresponding variety of different tolephone subs¢t configurations.
Other ob~octs, advantages and features of the ln-vention wlll be apparent~from the followlng detailed descrlp-tion and by referrlng to the accompanying drawlng~.
The drawlngs lllustrate the best mode presently 105'~9Z3 contemplated for carrying out the objects of the invention and its principles, and are not to be construed as restrictions or limitations on its scope. In the drawings:
Figure 1 is a perspective view of the telephone dial assembly of the type described in the invention.
Figure 2 is an exploded, perspective view of one embodiment of the telephone dial assembly according to the present invention.
Figure 3 is an electrical schematic, depicting how the switches shown in Figure 2 are employed to connect a TOUCH-TONE oscillator circuit to the telephone subset system.
Figure 4 is an elevational view taken along lines 4-4 in Figure 8.
Figure 5, illustrated on the same page as Figure 1, is a plan view used to describe the switching operation in accordance with a part of the invention.
Figure 6 is a perspective view of the same switching arrangement shown in plan view in Figure 5. -Figure 7 is an exploded, perspective view of another embodiment according to the invention.
Figure 8, illustrated on the same page as Figure 4, is a side elevational view of the composite assembly of the invention of Figure 7.
Figure 9, illustrated on the same page as Figure 6, is a perspective view of the bottom of a switching board used in the embodiment of Figure 7.
Figure 10, illustrated on the same page as Figure 4, is a sectional, elevation view depicting the operation of a portion of the embodiment according to Figure 7.
Referring to Figure 1, an assembled telephone push-button dial assembly 10 according to the principles of the present invention is shown. The embodiment of Figure 1 depicts the use of one particular set of mounting brackets 12 which .~ 8-:.,, ~ : ~ .

~os~s23 allow the basic as~embly 14 to be mounted in a certaln ~tatlon subset. The baslc assembly 14 is contoured about lts perl-meter 16 to mechanically fit into virtually all station subsets - -manufactured by the Western Electrlc Company and other domestic -equlpment suppllers as well as standard station subset configu-rations manufactured by various forelgn companios. As a result, the entire range of ~tatlon~-sub~ete rrom a single extension K-500 type to large capacity key telephone systems as well as PABX attendant consoles may be outrltted wlth this new assembly.
Referring to Figure 2~and the aceompanying descriptlon followlng, one can appreciate how the unlt o~ Flgure 1 iB as-sembled. me assembly lnclude~ an upper frame 18 whlch lncludes a plurallty Or apertures 20 arranged dn ~our row~`a~d three columns when the number of telephone pushbuttons is~twelve.
15 me apertures 20 are contoured to allow passage of lts corres-pondlng pushbutton shown typlcally at 22 whleh for purposes of this discussion is shown rectangular, Proferably, the upper fname lo made of a plastlc materlal.
Below the top surface 24 of the frame 18 i8 a downward extendlng appendage 26 which ~or the purposes of thls particular embodiment i8 rectangular in ~hape. The downward extending appondage lncludes a plurallty of notches 28 about its perimeter. ~-The appendage 26 has two sets of opposlng sldes which extond downward from the top surfaee 24 by dlfferlng amounts. One side of each set o~ opposing faces lo identl~ied by 30 and 32 respeeti~ely in Figure 2. Al~o extending downward rrom the top surface 24 of the frame 18 are ~ork-like proJectionc shown typleally at 34. meir purpose will beeome evident in the subsequent discussion. Finally, the upper rrame lô includes downward extending bosse~ 36 to which are secured ~ounting 105~9Z3 brackets 38 (or 12 as ahown ln Flgure 1) via mountlng cre~s (not hown) mounted wlthln approprlately threaded holes lnslde o~ tho bosses 36 Hole typlcally shown at 4O would bc employed to secure the overall assembly lO lnto a ~uitable ~ounting position wlthln the telephone sub~et When asse~bled the telophone pu~hbuttons would be inserted in the aperture~ 20 ~rom undern ath the upp-r ~rame 18 sueh that the shoulder~ 41 and 42 on each button N~uld contact ;--the underside 44 o~ the t~p surface 24 and thereby be pr~vent-d ~rom pa~sing through the aperture ln the upper rrame 18 The asscmbly as de~crlbed include~ t~clve pushbuttons all o~ the same basic ¢on~lguratlon The twel~e button~ includo th "
through "9" buttons ~am~llar to all telephone uscr- as ~ell a~
- "*" and "#" key~ which can be used to key certaln anclllary runctlons dc~crlb-d abo~
~ ach button ineludca in additlon to the ~houlders 41 and 42 additlonal shoulder~ 46 and 47 and an axially cJt-ndlng ",!, appendage 48 The shoulders 46 and 47 lle in respcctl~e planes ~
~hich prerer~bly ar~ p~rp~ndicular to the longltudla~l axi- Or ~ -20 thc button and whlch ar at di~rer~nt axial posltlon~ ~or .~t, rcason- whlch will beeome more evldent Flnally the buttQns lncludc a protrusion 5O which act- a~a guidlng m~mb-r r-strlct~
lng th~ ld- to ia- movoment Or the button when it~ depressed 1~ a m nner whlch wili soon bocome ovldent Ther- aro three colu~n~ Or button~, two o~ whlch are orl-nted such that the guldlng protruslon 50 extonds outward rrOm the button to tho '~
ri pt as vlowcd in tho diroction Or arrow A ln F1gure 2, wheroa~
tho protruslon 50 a~oclat-d with tho rlght-hand column buttons as vlcw-d alon6 the dlrectlon Or arrow A, oxtend~ to the left me roversal Or tho one column Or button~ allows 10.

.. .. ~ .

~os~9~3 one common button de~lgn to be ueed ln all twelve positions ~ ositioned below the upper frame 18 uhen finally assembled is a gulde plate 56 which, prererably, is al~o m~de from plastic The gulde plate include~ a surrace plate 58 which has a plurallty of apertures 60 corresponding to the number of pushbuttons and conflgured to reflect the outllno of the p rtion of the buttons below shoulder6 41 and 42, when viewed along the longitudlnal axlB Or the button Of course, the relati~e locatlon of each of the apertures 60 on the surface plate 58 correspond to the spaclng betwoen the pushbuttons them-selvee Extendlng upward from tho surrace plate 58 is an appen-dage 62 ~hlch follows tho contour of the downward extendlng appendage 26 of the upper ~rame 18 The appendage 62 lncludes a set of opposlng faces 64 extendlng upward at one helght from the eurface p~ate 58 and a second set of opposlng ~ides 66 ex-tendlng upward to`~a s-cond height me helght of the sets Or opposlng sldes is selected such that when the guide plate 56 18 socured to the upper frame 18 the appendage 62 is contiguous with the appendage 26 The appendage 62 include~ angled b~sses 68 which align themselves with appropriat- mounting bo~aes on the upper frame 18 (not shown) enabling the gulde plato 56 to be moehanlcall~ secured to the upper frame 18 The guldo plste 56-further includes a plurality Or slots 69a, b, c and d (not shown) whlch allow for cooperatlve actlon betwoen certain ones of thè append~ges on the longitudln~l rod~ and the sllde actua-tor bar as ldcntlrled herelnafter Intorposed between the upper ~rame 18 and tho gulde plate 56 are a plurallty of longitudinal and transverse rod~ 70 and 72~ respectlvely Th-se rods typically are slnc die cast Each of th~ rods lnclude a cyllndrlcal portlon 74 whlch rests ~o5~

ln its correspondlng notch 28 when the gulde plate i8 secured to the upper frame. Further, the rod~ lnclude a generally rect-angular shaped portlon 76 from whlch a plurallty Or appendages, o~ the type shown typically at 78 and 80, pro~ect transversely to the longitudlaal axi8 of each Or the rod~. The longltudlnal rods 70 include an addlt~onal appendage 82 whose functlon will be de~cribed later, Lastly, all Or the rods lnclude yet another appendage, shown typically at 84, which po~itions itselr in the openlng Or the ~ork-like proJection 34 when the cyllndrlcal por-tions 74 of the rods are located ln thelr respective notches28.
There 18 one transverse rod for each column Or buttons with the rlght hand rod as vlewed in the dlrectlon Or arrow A
or onted such that the appendages typlfled by 80 extend to the rlght. The two left most transverse rods a~ ~lewed ln the dl-rection of arrow A have the proJectlon or appendage typirled ~-by 80 extondlng outward from the rod in the left hand dlreetlon.
Thls conrorms to the orlentation Or the three columns o~ buttons.
There are flve longltudinal rods - three such rods allgned respectlvely with each of the rows eorre~pondlng to numbers "l", "2" and "3", row 4, U5~ and "6" and "7n, "8" and "9" as Nell a8 two longltudinal rods 86 and 88 whlch ar- acted upon by the buttons ldentifled by "*", "O", and "#". The need for the two rods 86 and 88 to lmplement the functlons per~ormed by a single rod ror each of the other three rows 18 due to the requlrement that the dial a~sembly bo lnsertable ln many var$ous -~subset outllncs. In order to ~ul~ill thls requ~rement, appllcants had to locate the eorrespondlng ~wiOch Or the 102 ~witch group-lng, ld¢nt~flea below, ln such a manner that there wa8 8UrflClent clearance between the dial as~embly and the assembly outllne of . .
-~a-~.o5~9'~3 each subset lnto which the assembly was to be lnaorted. Thlo forced an alternate arrange~ent to the use of a slngle rod.
Rod 88 of the two rod arrangement shown rotatlonally responds to downward movement of any button *n the bottom row with lt-78 type appendage operatlng upon the corre~pondlng one of the102 switch grouplng.
~ od 86 rotationally responds thereto wlth lto 82 type appendage cooperating wlth sllde actuator bsr 96 as dlscus~od below.
Likewlse the rlght hand rod, as vlewed ~n the direction of arrow A, of the tran~verse rod grouplng 72 had to be reversed from the other two ln order to lr~crease the adapt~bllity of the assembly. Thl~ ojoupled wlth the deslrablllty Or uslng the same button deslgn ~or all twelve button positlons resulted ln the reversal Or the rod as well as th oolumn Or buttono, "3", "6", "9" and "#".
Thc longltudinal and trans~erse rods 70 and 72 are lnterpo~ed between the guide plate 56 and the upper frame 18.
Because of the dlfrerence ln helght between the rlrst set of opposing side~ 64 and the second set of opposing sides 66 of the gulde plate 56, tho set of transverse rods 72 are po-ltloned in a first plane whlch is closer to the plano of the top ourface 24 than the plane containing the set of longltudlnal rods 70.
Of courso the planes of the rods 70 and 72 are sufficiently sepQrated 80 that the rod~ are unimpeded when they rotate ln response to movement of the varlous button~.
Po~ltloned below the ~uide plate 56 is a swltchlng board assembly 90. It lncludes a prlnted circuit tp.c.) board 91 which is, generally, Or a glass phenollc construction having copper paths po~itioned theroon for purposes of conductln!g ~o5~9Z3 electrlcity from one locatlon on the board to another. ffl e method for fabricatlng a p.c. board 18 well known in the art.
The board 90 includes ~lots 92 and 94 whlch locate a sllde actuator bar 96. The latter i~ interposed between the ~witchlng board and the underside of the guide plate 56. The slide actuator bar 96 generally 18 arranged such that lts longltudinal axis ls collnear with the longltudi~al axle of the tran~vcrse rods 72. The bar 96 lncludes a flrst and eecond set of trano-verse appendaged7 98 and 100, whlch extend respectl~ely upward through the slot in the guide plate 56 and downward through the slots 92 and 94 in the swltching board 90.
The actuator bar 96 preferably is manufactured from a plastic beeause of the latter's wear characterlstlc~ ~nd 1QW --coefiicient of friction. The first set of transverse appendages, 98, extend upward through the slQt in the gulde plate 56 and cooperate with the rlght angle, downward extendlng appenda~os 82 associated wlth each of the longltudi~al rods 70 except the one, 88. The cooperative relstlonship between the appendage ~-~
82 and the transverse appendagea 98 will be covered later on when a descrlptlon Or the overall operatlon Or the as~embly will be dlscus~ed.
Posltloned on the top s~de Or the switchlng board ass-mbly 90 i8 ~ fir6t set of ~wltches 102. Swltch 103 is lllw tratlve o~ each o~ the switches in this firat set. Each lncludes a first contact 104, a second contact 106 whlch in- -cludes a ~emlclrcular portlon 108 which pro~ldes the contact suriace between the contact~ 104 and 106. Sandwiched between the two contacts 18 an insulatlng mQterlal 110 which isolates the cont~ct 104 from the contact 106 when the ~witch 18 ln th~
rest posltlon The constructlon of the switch can better be 14.

~o5~923 seen ln Figure 4.
Rererring to Flgure 4, the contacts 104 and 106, in thc rlnal assembly, and thls i8 true of all switehes in this sot 102, ext~nd upward from the horlzontal plane, approxim~tely at a 45 an~le. Eaeh contaet, 104 and 106 inelude~ a horlzontal portlon, 112 and 114 respectively, between whieh lnsulation material 110 i8 pogitioned. The contacts 104 and 106 furth-r include downward extending portions 116 and 118. Th se latter portions extend through the p.e. board 91 and are ~oldered to copper paths thereon. The eontaets 104 and 106 preferably would be made Or gola plated beryllium coppor - an optimum m~terial for low eurrent (miero Q region) applieations whieh ha8 superior ~pring properties. In thé preferred embodiment the contaet 106 would have rorked or bifurested end as illustrated in Figure 2 This helps to minimize "¢onta¢t boun¢e~ - a soure~ of noise whi¢h ~~
18 undeslrablo in telephone systems.
AB notod earllor, the board 91 prererably 18 a prlnt~d eireult board whereupon there 18 etehed various eopper path-whieh make th~ ne¢-ssary eleetrical interconneetions ln aeeor-dance with the overall ~chematlc diagram ror the assembly. SomeOr the prlnted eircuit paths are lllustrated in Figure 6. In that ~iew, it i8 more readily apparent how the downward extending portions 116 and Il8 are conneeted to corresponding printed eircuit paths on the board 91. It 18 to be recognized that the ¢onReetions now to be deecribed are typical for each of the switehes in the ~roupin4s 102. The portlons 116 and 118 extend through the board on opposite sides of a roctangular cutout 120.
Eaeh of the portions 116 and 118 1~ then soldered to th prlnted clrcult path whlch is routed to the corresponding edge of the eutout 120. Thus the necessary electrlcal eo~nection~ between 15.

- ~o5~9,23 the swltch contacts 104 and 106 are made to the proper electrl-cal polnts on the board 91.
Figure 4 best lllu~tratee the mountlng of those switches in set 102 which cooperate with the transverse rods 72.
Flgure 8 best deplcts the mountlng of thos~ whlch cooperate wlth the longltudinal rods 70. Rererring to Flgure 4, a screw 121 is passed through appropriate openings (not shown) ln portion 112, lnsulat$cn~ matorial 110, portlon 114 and a stanaofr boss 122.
It i8 then passed through a corre~ponding openlng in p.c. board 91 and secured thereto by a nut (not shown). The boss 122 18 ~ -requlred because of the deslrablllty of using the ~ame ~witch - ~ ;
for each location s~d the fact that the ewitches which cooperate -~
with the transverse rods 72 must be elevated due to the fact that the plane of the latter i8 hlgher than the pl~ne of the 15 longitudinal rods. -`
In the preferred embodiment there are 7 ~ueh switches ln the set 102, three of which are respoasive to rotational move-me~t o~ the transverse rods 72 and fou~ of whlch aro respon~ive to the rotatlonal movemeat of the longltudinal rods 70. ~ ?-me prlnted circuit board 91 lncludes a plurallty Or openings therethrough. The circular openinge 124, 126 and 128 as well as a fourth opening not apparent ln the view Figure 2 are used to secure the swltchlng board assombly 90 uslng appro-priate mounting means to the upper ~rame 18. Further, the board 91 includes a plurality Or circulsr openings 129 whlch allgn themsel~es with the axially extending appendage 48 of each of the correspondlng pushbuttons 22. Lastly, the board includes appropriate openlngs 130 to enable pa~-age Or mounting bosses 132 whlch extend downward rrom the guldo plat 56 and whlch are employod to secure addltlonal electronlc assemblles to the 16, ~ (~5'~923 baslc dial Assembly.
Po~itloned on the back ~ide of the board 91 are a second set of swltches 134 whose position and arrangement are best illustrated in Figure 6. The following discu~sion will concentrate on the descrlptlon and operation of but one Or the switches which constltutes the set of switches designated 134 in Figure 2. It 18 understood, of course, that the remalning ewitches in the grouplng are Or identlcal constructlon and oper-ate in a similar manner. Switch 136 in the grouping include~ a terminal 138 whlch is suaged or press fltted lnto tho circult board 91. The terminal typlcally i8 made from brass whlch can be soldered at 140 to a correspondlng prlnted clrcuit path 141.
Tangentially connected to the termlnal 138 18 a contact ~trlp 142 which preferably is spot welded to the terminal 138 and which extends from terminal 138 across the back slde of the board 91. It is routed past a second terminal 143 whl¢h i8 se~
cured to ~he board 91 in the same fashlon as terminal 138. m e contact strip 142 extends beyond the polnt Or eontact wlth ter-mlnal 143 and tangentlally connects with yet another terminal, 144, which 19 socured to the board 91 ln a fashion ldentlcal with that Or the other terminals. The contact strip 142 iB
forked or bifur~ated at its end 146 which minimizes contact bounce when the swltch i8 opened and closed. The coRtact strip 142 is of sufricient length that it extends into the path of the transverse appendages 100 whlch, as noted earlier, extond downward as viewed in Figure 2 from the actuator bar 96 through the slot 92. Tho bifurcated end 146 contacts the flat surface 14~ of a corresponding one of the appenda~es 100.
The contact strip 142 18 made of sprlng-llko, conduct-ive material fiuch as gold plated, beryllium copper. Terminals ~05'~9Z3 144 are al80 gold plated to minlmize contact reslstance.me termlnals 138, 143 and 144 are arranged relati~e to each other such that the strip 142 is spring biased to pro-vide a contact between terminals 138 and 144 when none of the buttons are depressed. The ~prlng blas insures the necessary contact pressure between the strlp 140 and the terminal 144. Terminal 142, typically, i8 nothlng more than a pivot point which ensures that the contact strip 142 e~erts sufficlent pressure agalnst terminal 144 when none of the buttons are depressed.
In addition to the swltches which constltute the set 134, there ls a sprlng-llke means 150 which operates utilizing the same mechanlcal princlples a~ employed by each of the swltches in the set 134 but whose functlon it is to in~ure the reposltloning of the actuator bar 96 in its normal, at-rest positlon once a partlcularly selected button is no longer depressed. In order to max~m~ze this restorlng force, the correspondlng ~contact strip~ for means 150 does not employ a bifurcated end.
Referrlng agaln to Figure 2, (and Flgure 6), there is shown inserted at approprlate locatlons on the board 91, preferably along the edge thereof, means 152 for electrically connecting corresponding printed circuit paths on the switching board 92 and the electronic assembly board 154. m e means for interconnecting the two assemblies 90 and 154, ln the preferred embodlment, would include a plural~ty of pins 155 whlch would be soldered to appro-priate printed circuit paths on the board 91 on the one end and on the board portion of assembly 154 at the other.
The electronic assembly 154 is similar to the 18.

~OSZ923 board 90 in that lt llkewise lncludes a prlnted circult board fabrlcated in the same manner that the board 90 is fabricated. The assembly would lnclude (and lt 1~ not shown ln any of the drawlngs for purposes of clarlty) such ltems as the standard L-C TOUCH-TONE osclllator clr-cults which are shown schem~tlcally ln Flgure 3. Such an L-C clrcult or multl-frequency ~lgnal generator for the call transmlttor 18 depicted $n flgure 2b Or Unlted States Patent No. 3,479,470. In ~ome Or the more advanced adaptlons of the baslc assembly of the present lnventlon, the eleci tronlc assembly board 154 can lnclude a mlcro-circult ver-slon of the conventlonal touch-tone osclllator clrcuit plus addltlonal clrcults such a~ the repertory functlon earlier described, or a calculator or whatever might be easily packaged withln the outline of the assembly 154 as it ~its into the overall telephone subset.
Interposed between the switching board 90 and the electronlc assembly 154, when assembled, are a plurallty of coll springs 156 which align themselves with the axially appendage 48 Or a correspondlng pushbutton. Although Flgure 10 pertains more specifically to the next embodi-ment to be described, it can be referred to for purposes Or understandlng how the spring 156 cooperate6 with its particular button to provide a restorlng force which re-turns the button to its re~t positiQn after being depressed.
As employed in the Figure 2 embodiment, the bottom end of the coll spring 156, as viewed in Flgure 10, would contact the top ~lde of the p.c. board 157 used in the assembly 154. me coil spring extends up lnto a hollow cavity 158 wlthin the axially extending appendage 48 and cooperate~

19.

~05'~9Z3 with the top end of the cavlty 160 to exert an upwardforce thereon in respon~e to the depresslon of the button. In the embodiment of Figure 2, the plunger whlch 18 shown positioned wlthln or lnternal to the coll sprlng 156 in Flgure lO, i8 not requlred.
Where lt 18 deslrable to lnclude an addltlonal anclllary functlon, another electronlc as~embly 162 can be ~plggybackedU onto the underslde o~ the assembly 154.
me assembly 162 would include baslcally a prlnted clrcult board 164 similar ln construction to the boards 91 and 157, which would have packaged thereon, the LSI chlp embodying certaln ones of the anclllary ~unctlonJ mentioned abo~e. -Suitable lnterconnecting means, of a type ~imilar to 152, ;~
would be employed to electrically connect the a~sembly 154' to the assembly 162. Mechanically, the unit 162 can be secured to the mounting bosses 132 on the guide plate 56 `-through ~uitable mean~ 165. In the embodiment of Figure 2 those functions whlch can be included ln the LSI chlp to be packaged on the assembly 162 would be limited to those which dld not require any additlonal switching functions other than those performed bytthe ~ir~t and second set~
of switches, 102 and 134.
m e iinlshed assembly would include system hook-up means whlch would provide electrical connections between 25 the ~witches and electronic circults of the dial assembly -~
lO to the remainder of the telephone system. These hook~
up mean~ are not illustrated in Figure 2 but would generally ~;
consist o~ suitable hook-up wlre soldered to appropriate polnts on the p.c. boards 157 and 164.
Referrlng to Flgure 7, there ls shown a preferred 20.

105'~923 embodlment whlch expands the number of avallable swltchlng contacts and whlch, consequently, enables the incluslon of additlonal anclllary functlons a~ part of the electronlc assemblles 154 and 164. The constructlon of the dlal assembly from the frame 18 and through the 6econd ~et of swltches 134 posltioned on the back slde of ~wltchlng board 90 18 identlcal to the constructlon expounded upon with regard to Figure 2. Flgure 7 deplcts an extenslon of the baslc deslgn whlch 18 most readlly understood by ~tudy-lng Flgures 7, 8, 9 and 10.
In the embodlment of Flgure 7, the assembly 154lncludes a prlnted circuit board which is substantlally ldentical to lts counterpart ln Flgure 2. Here however, as can be best seen ln Flgure lO, provlslon 18 made to enable a plurallty of bushlngs 168 to be lnserted ln corre~ponding holes 170 ln the p.c. board 157. m ese are aligned with a correspondlng one of the axially extending appendages 48.
The bushingo can be pre~s fltted from the underslde of board 156. They lock themselves into place by means of ~.
resilient flange 172 whlch returns to a rest posltion, once through the board, such that the shoulder of the flange 172 in contact with the top side Or the board 157 prevents the bushlng from backing out. me bushing 158 ~urther ln-cludes a circular flange 174 axlally dlsposed from the flange 172 such that the spaclng between the underside of rlange 172 and the top ~lde of flange 174 is approximately equal to the thlckness o~ the p.c. board 157. This con-sequently reduces the up-down movement of the bushings ln the holes 170.
The bushing has an opening 176 which reduces down 21.

` ' ` ' ~a5~9Z3 to a small circular openlng 178 at the top slde of the bushing. me bushing itself 18 made out of a pliable materlal such as plastlc which would allow it to be pressed through the p.c. board 157 as described abo~e.
Posltioned on the underslde 180 of p.c. board 157 is a plurallty of leaf-epring swltches 182. These switches, like the prevlou~ly descrlbed sets of swltches 102 and 134, are fabricated from a material such as gold plated, berylllum copper which minimizes the reslstance between the contact portlons of the switches and the printed clrcult lands or paths which are located on the underslde 180 of p.c. board 157.
Referring to Figures 8 and 9, each of the leai-spring switches includes a flat portion 184 which can be riveted or soldered to the p.c. board 157 in a manner suit-able to insure an electrlcal connection between the portion 184 and the printed circuit path which runs underneath the portion 184. Each leaf-spring ~witch further includes a ~ide portion 186 which i~ essentially perpendicular to the flang~ portlon 184 and which extends downward, as viewed in Figure 8, from the plane of the board 157. The swltches ~ further include a portion 188 which extends back from the ; extremity of downward extending portion 186 towards the underside 180 of the p.c. board 157. These portions 188 ~¦ 25 terminste in an arc-shaped section 190 which is 80 con-~- flgured to maximize the contsct surface between each of the leaf-spring switche~ and the printed circuit paths positioned below the section 190. me switch is fabricated such that the arc-~hsped portion 190 is ~pring biased against ~; 30 the printed clrcuit path thereunder when the buttons are .
`~ 22.

~05'~9;~3 not depressed. Thls further ensures good electrical contact.
Returning to Figure 10, the sprlng switche~
are posltioned on the p.c. board 157 such that the opening 176 of bushings 168 is opposite the portion 188 of the corresponding switch.
In the embodiment shown in Figures 7 through lO, there is inserted within the coil spring 156 a cylindrical plunger 192. The coil spring 156 is supported at the bottom thereof by the top 194 of the bushlng. Referring to Figure lO, it iB seen that the plunger 192 is Or sufri-cient length that it contacts the topside 160 of the cav-ity 158 on the one end. It is aligned by ~e narrow opening 178 to be posltioned over the portion 188 and contacts the latter when its corresponding button is depressed. m e plunger is of sufflclently low mas~ that it is free-floating and responds to movement of the button or portion 188 of the leaf spring.
As is the ca~e with the embodiment of Figure 2, 20 the embodlment of Figure 7 i8 adaptable to provide for the -mounting of an additional electronic assembly 164 to the mounting bosses 132 on the guide plate 156. Because of the additional switching provided by the leaf-spring switches, the ancillary functions that can be packaged on the assembly 164 can be different than those pack~ged on the simllar assembly assoclated with the embodiment o*
Figure 2~ They can include the repertory dial function, the toll re~trictor *unction. Where the as~embly 18 used to replace the standard rotary dlal assembly, the out-pulsor *unctlon prevlousl~ described can be part of the 23.

lOS'~9'~3 LSI chlp which i8 mounted on the p.c. board 162.
me operatlon Or each Or the e~bodiments will now - be described.
The flr~t part of the dlscu~slon will concentrate on describing how respective swltches in the set 102 rospond to the depresslon of corresponding buttons. As noted earller there are se~en such switches for the three column and four row arrangement deplcted. Thus there 1~ *ne swltch in the grouplng 102 for each row and each column.
The requirement for seven ~witches Or the type ldentlfied generally by 102, 18 partlcularly necessary where the ~;
electronlc assembly packaged on a~se~bly 154 includes the touch-tone oscillator circuit. ;~
The schematlc of Flgure 3 represents ~ust such an oscillator clrcuit which generates, slmultaneously, a high and a low rrequency in osclllator circuits 196 and 198, ~ ~ ~
respectively. A~ 18 well know ln the art, there 18 a ~ ~ -unique pair of rrequencles generated for ea¢h Or the buttons, ~0 through Ng~ when the partlcular button i8 depressed.
For purpose~ of illustration consider the operatlon of switches 103 and 202 which are two of the se~en swlt¢hes which comprise the set 102. In order to better under~t nd ~-the following dlscus~lon the reader should refer to Flgures 2, 3, 4 and 8.
or necessity, the description of how the operation of switches 103 and 202 tles in with the generation of the unique osclllator rrequencles will be tied in with a dls-cussion-of how the depressed button cau~es its respective longitudinal and transver~e rods to rotate.
The parts of the switch 103 were labeled durlng the 24.

~05;~9Z3 prior dlscussion of the construction Or the dlal as~embly.
For purposes of facilitatlng the followlng dlscusslon, the switch 202 lncludes a flrst contact 204, the end of which, 206, rests under appropriately shaped boss 208 which iB
part of the upper frame 18, Further, the switch includes a second contact 210 which contacts the downward extendlng appendage 78 of one of the longltudinal rods 70. As shown in Figure 8, the buttons are ln an at-rest position. The boss 208 cooperates with the first contact 204 whkch is sprlng biased thereagainst to insure that the contacting surface between contact 210 and the semi-circular portion 212 ~ -of the first contact 204 are maintalned in an open condition when button 54 is in the at-rest position.
When the button 22, which as can be seen from 15 Figure 2 corresponds to the number ~6~, is depresQed, shoul- -~
der 46 on the one hand moves downward contactlng the upward oxtendlng appendage 80 on the correspondiAg tranverse rod in grouping 72. Shoulder 47 contact6 the appendage-80 on the correspondlng longitudlnal rod in grouplng 70. These rods consequently rotate about thelr respective tubular portlons 74 positioned in their corresponding notch 28.
Referrlng parti~ularly to the corresponding long- ;
ltudlnal rod, as it rotates, the appendage 78 turns downward forcing the second contact 210 downward to touch the ~emi~
clrcular contacting portion 212 of the first contact 204.
me switch 202 has thus gone from an open to a closed posi-tion. Similarly, the transverse rod in the grouping 72 responds ln much the sa~e manner so that upon rotation, the flange 214 force~ the first contact 104 down towards the semi-circular contactlng portion 108, thus closlng the second 25.

~ 05,~ 3 swltch. m us it i8 when anyone of the buttons are depresaed.
- However, a careful study of the rigures, particularly Flgure 2 and Figures 4 and 8 will show that for any particular button, a unlque pair of switches will be actuated.
When the finger is removed fro~ the button, the sprlng-restoring force lnherent in each of the contacts 104 and 210 exerts an upward force on the appendages 214 and 78, respectlvely, returning the correspondlng transverse and longitudinal rod~ to their at-rest position. If one 10 now refers to Figure 3, it can be seen that the closing of ~-switches 103 and 202 result in the selection of particular taps on the secondary o~ transformers 216 and 218, respec tively. These partlcular taps, along with the other com~
ponents in the oscillator circuits 196 and 198, are selected 15 in accordance with principles well known to tho~e skilled `-in the oscillator design art, to generate two rrequencle~, corresponding to the ctandard frequencies employed in TOUCH-TONE systems3 which represent the numeral or dlgit ~6 Referring to Figures 2, 5 and 6, the actuation of the switches in the set 134 will next be described. All of these swltche~ in the group 134 are activated whenever any button is depressed. Thus they are ~ailable to be used in any telephone circults, well known to those ln the telephone systems art~ which must respond whenever any button is pushed.
For example, when the button 22 is depressed and the longltudinal rod corresponding to that button 18 csused to rotate due to the cooperatlve action between the upper extending appendage 80 and the shoulder 47, the downward extending appendage 82 rotate~ and in 80 doing contacts the 26.

105;~923 transverse appendage 220 on actuator bar 96. Thl8 can be best seen in Flgure 2. Thi~ results in the sllde actuator bar in a linear fashion, direction B ln Flgure 5, in the slots 92 and 94. me various transver6e append~ges iden-tifled generally as 100, of cour~e, move ln the same direction, ;-B. Typically, the flat surrace 148 of the various appendages contact the strip 142 after movement of a minimum amount.
m e contact between strip 142 and the terminal 144 18 broken, thus interuptlng the electrical connectlon between terminal 138 and terminal 144.
The grouping 134 is ldentlfied in the schematic Figure 3 with the particular switch formed by terminals 138, 144 and strip 142, particularly identified. m e switch posltions shown would be those which exist when the buttons are ln the at-rest position.
As noted earlier, spring-like means 150, preferably, is made of a strip similar to contact strip 142 but which ~ ;
generally is not blfurcated. This increases its restoring force capability. It exerts this force through one o~ the second sets of appendages, 100, to the actuator bar 96 80 that the latter i8 returned to its at-rest position when the operator~s flnger ls remo~ed from the button.
The Nthird plane~ of switching whlch expands the potential o~ the previously described asse~bly of Figure 2, will now be described with reference particularly to Figures 7, 9 and 10. Referrlng to Figure 10, when the button 22 is depressed, the top side of cavity 160 contacts the upper end of plunger 192. The latter is rorced downward through the narrow opening 178, through the opening 176 until the plunger contacts the board-facing side of portlon 27.

~05'~9Z3 188 Or the correspondlng leaf-spring swltch, forclng the latter downward as vlewed ln Figure lO. m 18 lnterrupts the electrlcal connectlon formed between the arc-shaped portlon l90 and the prlnted clrcult path posltioned there-under. Thus the electrlcal connectlon between the printedclrcult path under the portlon 184 of the leaf-sprlng swltch shown and the electrlcal prlnted clrcult path under the por-tlon l90 is opened.
; When the button ls depressed, the coil sprlng 156 whlch has a dlameter larger than the opening 178, becomes colled agalnst the top of the bushlng 194. When the oper-ator's ~inger 1B removed from the button 22, the restoring force built up ln the coll spring 156 is exerted agalnst the top of the cavity 160. This forces the button 22 up-ward untll the shoulder 41 contacts the underside of thetop surrace 24 of the flange 18.
Once the top side Or the cavity 160 18 freed from the correspondlng end of a plunger 192, the restoring force ln the sprlng contact portion 188 exerts itself on the bottom end of the plunger 192 forcing lt upward untll the arc-shaped portlon l90 again comes in contact wlth its corresponding printed circuit path.
Thu~ through the improved embodiment shown in ~-Flgure 7, an addltional plane of swltchlng, provldlng 2~ twelve addltlonal switching functions which open and close in response to a corresponding digit being depressed, i~
provided. Through application of suitable voltage levels on the variou~ printed circult paths contacting the plu-rality of portlons 184 and l90, digltal loglc levels can be generated indlcatlve of the open or closed posltlon 28.

~ 05'~923 Or the correspondlng leaf-~pring ~wltch. mese loglc levels can be lnterrogated by suitable loglc clrcuitry 80 that the particular digit depressed can be ldentlfied. It 18 obvious to those skllled in the logic deslgn art how thls lnfonmatlon could be utlllzed t~ provide addltlonal ancillary functions and partlcularly those enumerated above.
m e lmplementatlon of the6e additional anclllary functlons glven the increased number of switchlng contacts provlded by the third plane of switching and the advancement in the state Or mlcro-circuit development, partlculârly large-scale integration, would be obvious to tho~e skilled ln diglt-al circuit and loglc design.
In certain situations it may be desirable to delay the tlme when the switching runctions performed by the first -~
and second ~ets of switches, 102 and 134 are operated and ;-when the functions implemented by the third plane of switches are performed. This time can be adJusted by Judicious de-slgn of the relative spacing between the shoulders 4Ç and 47, and the length of the hollow cavity 158 internal to t~e axially extending portlon 48.
It is to be appreclated that changes ln the above embodiments can be made without~departing from the scope of the present lnvention. These changes would be apparent to those ~killed ln the art but must be consldered within the scope of the inventlon as de~lned in the appended claims.

29.

Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:-

1. A telephone pushbutton dial assembly which comprises:
(a) an upper frame including a plurality of apertures arranged in rows and columns and further including a downwardly extending appendage having a plurality of notches and its perimeter;
(b) a pushbutton mounted for movement in each aperture, each of said pushbuttons including a plurality of shoulder portions and a singular axially extending appendage;
(c) a guide plate including an appendage having the same perimeter as said upper frame appendage and including means for mounting said plate to said upper frame;
(d) a plurality of longitudinal and transverse rods, rotatably mounted in a first and second plane, respectively, between corresponding opposite ones of said notches and retained in said notches when said guide plate is mounted to said upper frame, each of said rods including a plurality of appen-dages transverse to the longitudinal axis of their respective rod, certain ones of said appendages adapted to cause rotational movement of its as-sociated rod through cooperative action with said shoulder portions of corresponding ones of said buttons;
(e) first switching means, including a first switching board having at least a first set of switches mounted thereon cooperating with certain other of said appendages and adapted to make or break in response to the rotational movement of said rods;
and (f) second switching means including;
(i) a second switching board positioned in a plane parallel to and below the plane of said first switching board, said first and second switch-ing boards having a plurality of corresponding openings each aliened with a corresponding one of said axially extending appendages, (ii) a plurality of leaf-spring switches fixedly secured to said second switching board, each of said leaf-spring switches aligned with a corresponding one of said axially extending appendages, each of said leaf-spring switches making an electrical connection between two points of electrical potential on said board, and (iii) means aligned with each of said axially exten-ding appendages and its corresponding openings in said first and second board, and operatively connected between said appendage and its cor-responding leaf-spring switch, whereby said electrical connection is broken when the cor-responding push-button is depressed.

2. The dial assembly of claim 1 further comprising means for mounting said dial assembly into a plurality of different telephone assembly configurations.

3. The dial assembly of claim 1 where the axially ex-tending appendage of a corresponding pushbutton has a predetermined length dependent on the time interval desired between when said first switching means responds to said rotational movement and when said second switching means responds to movement of said corresponding pushbutton.

4. The dial assembly of claim 1 further comprising electronic assembly means, including at least one electronic circuit, said electronic assembly contoured and mounted to said dial assembly of claim 1 in a manner that said dial assembly can be installed in a plurality of different telephone assembly con-figurations, said electronic circuits operatively connected through either of said first and second switching means to telephone circuits mounted in the telephone assembly or outside thereof.

5. The dial assembly of claim 4 where said first switching board further includes:
(a) a slide actuator bar mounted in a slot in said first switching board, said bar including a first and second set of transverse appendages, said first set cooperating with certain ones of said appendages affixed to said longitudinal rods to convert said rotational movement of said longitudinal rod to linear movement of said bar; and (b) a second set of switches positioned on the back side of said first switching board and adapted to be responsive to said second set of transverse appen-dages on said bar when said bar is moved linearly.

6. The dial assembly of claim 5 where said first and second sets of switches are comprised of switches wherein at least one contact of each switch is bifurcated.

7. The dial assembly of claim 5 where each of said axially extending appendages is hollow and where said second switching means includes:
(a) a plurality of plungers each positioned within a corresponding coil spring having a predetermined spring constant; and (b) means for nesting said spring and its associated plunger within a corresponding hollow;

8. The dial assembly of claim 7 where said electronic assembly means is mounted on the back side of said second switching board.

9. The dial assembly of claim 7 where said second switching board also includes thereon at least one other type of electronic circuit which is electrically connected through said first and second switching means to telephone circuits mounted in the telephone assembly or outside thereof.

10. The dial assembly of claim 7 where one end of at least two of said leaf-springs are connected to the same point of electri-cal potential.