CA1238099A - Electrical connector for disposable electrode - Google Patents

Abstract

ELECTRICAL CONNECTOR FOR DISPOSABLE ELECTRODE
Abstract A small plastic connector is provided with a unique electrical contact mounted in one jaw of the connector to mate with an angled edge on the other jaw of the connector to crimp and securely grip a thin, flat, flexible electrode in the connector while making good electrical contact. The jaws and the contact are further constructed so that the conductive surface on the electrode is pressed into engaging with a large contact surface.

Description

8~

ELECTRICAL CONNECTOR FOR A DISPOShBLE ELECTRODE
BacXqr~und of the Inv~ntio~
I. Field of the l~vention This invention pertains to electrical connecto~s, speci~ically an electrical connector to grasp a flexi~le, lightweigh~ electr~de.
Doctors in ~offices, clini~s ~nd hosplt~ls around the wcrld u~e ~le~trocardiogram~ Eor diagnostic purpo~s. To produce electrocardiograms an electrode i~ applied to the skin and used to detect change~ in electrical potential produced by the contractions of the heart. Typically, to make electrical contact with the ~ki.I~, medical personnel apply a solution and ~trap lar~e metal electrode~ to the body. In some in~ance~, this is done by u~ing a ~uction cup~ Many problems result from thi~ method of applyi~g electrodes. Among the problems are the me~s a~sociated with applying a ~olution to the body, ~nd the storage o~
the strap~, electrodes, suction cups and solution~.
Fur~her pro`blems include the inordinate amount of time required by personnel to apply the elsctrodes and possibility o~ unsatis~actory electrical contact with the body.
~ o allevia~e the~e problems a flexible, disposable electrocardio~ram electrode was developed. Conductive ~ell-adhe~ive applie~ to a paper-backed conductive foil provides for a lightweight, convenient and disposable electrode. Thi~ electrode is easy and quick ~o apply, and i9 deformable for application on most any part o~ the body. ~ Furthermore, it requires ~o application of an electrolytic ~olu ion and i~ com~ac~ and easy to ~tore.
The diepo~able electrode al90 provldes good electrical contact with the skin.
lI. Prior Art Relatinq to Disclosur~
3S Variou~ mean3 exlst to conn~ct l~ad wir~ to electroda~ or eLectrical t~minal#. One cQmmon typ~ of oonn~r o~i~ts o~ two pivotally m~unted, ~pring b~a~ tal ~23~

jaws having multiple t~eth for gripping an ~lectrlc~l ~erminal or ~lectrode. One ~xampl~ o~ thl2 i~ referr~d to a3 an alligator clip.
Problem~ arise, however, when m~dical perso~nel use me~al ccnnector~ to connect the lead wire~ f rom an electrocard.iograph-to the disposabl~ electrode. The met:al connector~ ~re too heavy and tend to pull off the lightwelght electrode~. Furthermore, the multi-tooth~d metal jaw~ pierce the thin conductive foil. Prior axt metal connector~ are gen~rally designed to grip much more ~ub~tantial electrode~. The pointed te~th, a~ociated with the prior art, provide only a ~mall area to di~per~e the gripping force~ Consequently, the metal connectors pierce the thin conductive film With ea~e. The8e problem3 hinder thc performance o~ the di~po~able electrQde by leading to poor electrical ront~ct with the body. As a consequence, ~ome health-care personnel believe di3posable electrod~ do not work properly.
Becau~e of the problem~ as~ociated with using a ~nventional metal connector on tha dLsposable el~ctroda, there i~, a d~finite need for a device that i~ ~mall, lightweight and which makes electrical contact with the electrode without piercing the conductive film.
Sun~ar of the Invention The electrical : connector of the invention i particularly u3eful in ~olving maTIy of the probl~ms a6 ooiatsd with prior art connectorq u~ed with di~po3able electrode~. The connector is lightw~i~ht and will not pull off the di~posable electrode~ due to a unique gripping surface. Thi~ unique ~ur~ace allow~ the electrical connector to maintain a good grip on the di~po~able electrode without piercin~ ~he foil conductor. qhe electrical cons~ector in~lude~ a pivotally moun~d upper and a lower jaw, pr~f~rably made of a lightweight pla~tic material. Hou8ed within tha lower jaw i~ an electrical contact preferably having a cylindrical ~3~

portion joined to a generally frustum-shaped portion. The larger end of the frustum adjoins the cylindrical portion and forms an angled shoulder extending toward the upper jaw.
Carried on the upper jaw is an angled edge portion extending ~oward the lower jaw. The angled edge portion is located so that upon closing it does not engage the shoulder yet extends beyond the shoulder and stops in a position closely adjacent to the shoulder. This allows the angled edge portion and the contact shoulder to crimp the flexible electrode.
The jaw is also formed and arranged so that the conductive surface of the electrode is held against the surface of the contact.
According to a broad aspect of the invention there is provided an electrical connector for connection to a thin, flexible electrode used in performing electrocardiogram tests comprising:
a pair of pivotally mounted jaws having tips which are biased into gripping position;
an electrical contact supported in one of said jaws having an angled shoulder extending towards the other jaw; and an angled edge portion carried by said other jaw and extending towards said one jaw closely overlapping but not engaging said shoulder so that the thin flexible electrode placed between the jaws is crimped between the shoulder and the edge portion with a conductive surface of the electrode engaging said contact.
In accordance with another broad aspect of the invention there is provided an electrical connector for connecting a thin, flexible, disposable electrode to the lead wire from an electrocardiograph machin~ comprising:

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a pair of pivotally mounted jaws made of lightweight, electrical.ly insulating material and having a generally plate-like configuration;
spring means urging the rear portions of the jaws apart and urging the tip portions of the jaws into contact with each other;
an electrical contact including an enlarged tip portion positioned .in a recess in one of the jaws with a frusto-conical portion extending towards the other jaw, and with the frusto-conical surface tapering towards the forward tip of the jaw;
an angled edge portion on the other jaw extending toward the contact tip, the angled edge portion being located to over-lap with, but not engage said contact shoulder so that a tab on said flexible electrode to be received between the jaws is crimped between the angled edge and the con-tact shoulder; and said other jaw having depending ramps formed thereon that extend toward the jaw containing the contact, the ramps located along the edges of said other jaw to straddle the : contact tip portion to wrap the flexible electrode around the frusto-conical surface of the contact tip, said ramps being tapered rearwardly and toward the contact jaw sufficiently far such that the ramps guide the jaws onto the flexible electrode and prevent the electrode from catching on the angled edge.
In accordance with another broad aspect of the invention there is provided the combination comprising:
a thin, flexible electrode having a thin, electrically-:~ conductive layer positioned on a thin, flexible backing layer;

and -3a-B

~3~ 9 6~742-~71 a lightweifht electrical connec-tor gripping an edge portion of the electrode, said connector having a pair of mov-ably-mounted jaws of insulating material having tips which are biased into gripping position on the electrode, an electrical contact positioned in one of the jaws extending towards the other jaw and having a portion for connection to an electrical lead wire, and an angled edge portion carried by the other jaw and extending toward the contact, the edge portion being closely adjacent to and in overlapping relation with the contact but not engaging the contact, with the flexible electrode being crimped between the angled edge and the contact, with the conductive surface of the electrode being held in firm engagement with the contact.
Drawings Figure l is a perspective view of a person using the electrical connector for a disposable electrode.
Figure 2 is an exploded perspective view of the electrical connector from the top.
Figure 3 is an exploded perspective of the electrical connector from the bottom.
Figure 4 is a cross-sectional view of an assembled electrical connector shown gripping the tab of the disposable electrode.
Figure 5 is a cross-sectional view of the tip of the electrical connector while ln an open position.
Figure 6 is a cross-sectional view taken along line 6-6 in Figure 4.
Detail ~
Referring to Figures 2 and 3, the preferred embodiment of the electrical connector comprises an upper jaw l and a -3b-B

~3~

lower jaw 2 connected by pivot pin 6, a contact but-ton 7, an electrically conductive contact 8, and a spring 4.
The contact 8 includes an elongated cylindrical body 31 joined at one end to an enlarged tip 32 having in its preferred form a substantially frusto-conical shape. The lower side of this tip is cut to form a flat lower wall -3c-B

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32a which is gener~lly perpendicular to the qmall and large end ~urfac~ or base~ 32b and 32e of th~ tip. As may be ~een, the larger end of the tip i connected to the cylindrical body 31 and ha3 a radiu~ larger than that of the cylindrical body ~uch that the larger end wall 32c o~
the tip form~ a ~h~ulder. The ~malle~ end of the enIarged tip has a radius ~pproximat~ly equal ~o that of the cylindrical portion 31.
The rear end oP the cylindrical bocly 31 ha~ a cavity ~haped to receive the unln~ulated portion of an electrocardiograph lead wire 5. Snugly moun~ed on the in~ulated portion of the lead wlre 5 i~ a tubular, elongated ~train reliever 3 having a centrally located ~quare plate 36 which extendq vertically to perform a strain xelie ~unction.
The jaws 1 and 2 are preferably made of a strong, la~lweight, electrically-insulating pla~tic material ~uch as phenylene oxide resin, one auitable example being ~old under the tradename ~yton, produced by Phlllips Petroleum Company. The lower jaw 2 has a ganerally rectangular ~hape lncludi~g a lower base or plate 33 havin~ a generally fla~ lower ~urface, a~ well a8 a flat upper ~ur~ace having rece~ses .formed ~h~rein and projection~
extending upwardly therefrom. A pair of parallel walls or ~: projection~ 37 extend upwardly from the pla~e 33, and ; extend rom the rear of the plate 33 to a point ~lightly : beyond the lengthwise middle of the plate. The w~lls al~o ~traddle th~ longitudinal center lîne of the plate ~o : define a ~pac~ for receiYin9 the contact body 31, the lead wire 5, and the ~train reliever 3. Located toward the rear of th~ jaw 2 in the inner surPace of the walls 37 and 38 are two notehes 11 which receive the plate 36 of the ~train reliever. Formed on the ~o~ward ends o~ the up~t~ndin~ w~ 3 37 and 38 are two tran~versely extendling 3 pi.n hol2s 12 aligned to receive the pivot pin 6, pivot~lly connecti~g the jaws 1 and 2. Al~o formed in the upp~r surface of the lower jaw plate 33 are two clearance rece~s~ lS, located outwardly from the wall~ 37 and 38, generally concentric with the pinholes 12~
Also formed in the upper ~urface of lower jaw plate 33 iq a rece~s 18, centered along the longitudinal center line of the plate-33. The reeesq 18 includes a Eorward trapezoidal por~ion 19, shaped to receive the lower portion of the y onkact tip 32 and thu~ po~ition the contac The reces~ also has a ~mi-cylindr~cal trough portion 10 for receiving the contact cylindrical portion 31. Thi~ trough extends from the base of the trape.~olclal portion 9 to the rear oE the lower ~aw plate 33.
The upper jaw 1 al80 has a gen0rally rectangular ~hape including a~ ~pper plate with an e~entially flat upper sur~ace and a lower parallel urface having internal rece~se~ formed thereon. ~wo parallel ~ide walls 39 and 4~ depend from the out~r edges of the plat~ 34, perpendicular to the plate. These wall~ depend the great~3~ amount near the center of the plate and then taper rearwardly. The central lower edges of th~e wall~
are curved to generally conform to the recesses lS in the lower jaw. Located approximately along he shorter ce~ter line of the hori ontal plate 34 on the out~ide o ~he idewall~ 39 and 40, are a pair of pin notche~ 16 which at their lower end~ fo~m opening~ through the walls 39 ~nd 40, and are aligned with the pinholes 12 of the lower 3aw.
o d~pending from the upper jaw plate 34 along the outer edge~ of the plate, are a pair of forwardly ex~ending ramp~ 41 and 42. As may be 3een~ the reaxward portion~ o~ the e ramp~ are adjacent the ~orward portions o~ th~ wall~ 39 and 40, and the ramp~ taper upwardly toward khe forward tip of the upper jaw.
Al~ formed in the upper jaw plate 34 i~ a buttonhole 37 for receivirlg the upper cylindri~al por'cion 7 a ~Of th~
button 7. For~ned in the rear portion of th~3 lower l~ur~ace of the upper plate 3~ a ~prlncJ receivln~ rec~ or notch 20. The no~ch i3 shaped to r~calva th~ upper end c: f ~he 1at, e~3~ntially U-shaped 8pritlg 4~
Referrlng to Figure 4, 1:he connector compon~nts are shown in a ~embled condition with the jaw~ in clo~ed position. As may be ~een, the flat, 1exible ~pring 4 i~
ormed in a loop ~between the rear o:f the connector jaws with one end being ~ecured in the notch 20 in the upper jaw and the ot;~r end being positioned by the ~train reliever plate 36. The contac~ 8 i~ shown posltioned in i t~ recee~ n the lower jaw plate 33 with the lead wire 5 and the ~train reliever 3 being c~ptur~d betwenn the vertical walls 37 and 38 on the lower jaw. Note that the upper portion of the ~ru~to-conical tip 32 ex~ends above the upper ~ur~ace of ~he lower jaw plate 33 toward~ the 15 upper jaw 1. However, the forward 0nd o ~he contact tip 32 is approxlmately f lush with the upper ~urfac~ of the plate 33.
The contact button cylindrical portio~ 7a ia ~hown captured in the hole 17 in the upper plate and its lower, generally rectangular portion 7b that extend~ beyor~d the : cylindrical portion 7a engage0 the }ower sur~ace of the upper jaw plat~ 3~. The forward proj0cti~g edge portion : 7c formed by a lower ~urface 7d and forward wall 7e of the button 7b may be seen to be positioned clo~ely adjacent to the ~houlder 32c on the contact tip. The iEorward wall 7e extend~ at an angl~ with respect to the lower surace 34a o~ the upper pla~e 34 at approximately '15. ~he contact houlder 32c defirled by ~he larger end of ths tip, extend~
at an angle of approximately 90~ with the upper and lowar . ~ur~aces ~f the lower plate 33. The upp~r and lower surface~ of th~ jaw plate6 in their clo~ecl position ~orm an acute an~le of approxim~tely 15~. Thi~ reault~ ln the forward ~e wall o~ the angled edge 7c being approxi.mately parall~l to the contact houlder 32c w~en the jaw3 ar.e in a clo~ed poaition a3 ~hown in Figure 4.
When the connector 5~ of the lnvention i6 to be positioned on a flexible electrode 50 o the type ~hown in Figure 1, the rear portions of the connector jaws 1 a~d 2 are gripped and squeez~d toward~ each other to ope~ tha jaw~. ~ote that the inger and thumb uaed for gripping the rear o the~jaw~ are con~lderably wider than the width of t~e jaws. This illustrate~ the mi~lature nature Gf the connec~or. In a pre~erred form of th~ lnventlon, the ~,~w~
are only about 5/16th~ o~ an lnch in w~dth. Th~ ctrode has a conductive foil lower ~urface ~upported by ~n upper bac~ing ~heet of paper or pl.a~tic. ~he ~urEace o~ the foil layer to b~ attached to th~ patl~nt'~ body ha~ n ~uitable conductive adhe~ive ~hereon. Such a di~po~abl~
electrode i~ marXeted by Harco Medical Electronic~
Device~ Inc. oE Irvine, Calirorni~.
Depre~sing the rear portion~ of the jaw~ again~t the urging of the ~pring 4, open~ th~ ~aw tip~ a~ ~hown in Figure 5. In thi~ po~ition, the upp~r ~aw plate 34 1B
approximately parallel to th~ lowar ~aw plate 33. Thl~
may al~o be ~een in broken line~ in Figure 4. With ~he jaw tip~ open, ~hey may be eaaily pl~ced over th~
electrode tab 51. Si.nce -the lower ~dq~ of the ramp~ ~1 and 4~ extend below the angled edge 7c of the contact butto~, and ~ince the tab 51 on th~ flexible electrQde i~
wider tha~ th~ jaws/ the tab i~ guided b~tween thH ~aw~ by he r~mpR 41 and 42 and cannot catch on the a~glsd edga 7c. Additional guiding action i~ provided by the upper curv~d, tapered ~urface of the contact tiLp 32 which extends above the upper surface of the lower j~w plat~
33. AS ~e~n from Figure~ 4 and S, this ~ur~ace tap~r~
upwardly and rearwardly, thu~ also guidlng the tab 51 80 that th~ jaws are ~moo~hly pl~ced over ~he ~lexible tab.
~el~a~ing the connector jaws cause~ the sprLng 4 to move the jaw tips into the clo~ed or gripping po~itiLo~ oE
Flgure 4. Upon closing around the tab Sl~ the angled ~2~

rel~tion oE the angled edge 7c, the con-t.act ~ip shoulder 32c, and th0 jaw tips re~ult~ ln the anyled edge 7c ju~t clearing the upper edge of the ~houlder 32c of ~he electrical contact 8, crimpin~ the tab Sl between the angled edge 7c and the contact shoulder 32c. As seen, ~he shoulder 32c and~ the angled edge 7c are es~tlally parallel to each other upon clo~ing~ with ths dist~nce between them b~L~ ~lightly les~ than the thickne~s of the tab 51 H0 that the tab ~ B securely ~ripped. Stated otherwi~e, the an~led edge 7c clo~ely overlap~ or extends adjacent to the contact ~houlder but doe~ not eng~ge it o Thu~ it is so~ewhat in the nature of a shearirlg action without any cutting or tearlng of the somewhat fragil%
tab~ It should also be noted that the angled edge 7c and the contac~ ahoulder 32c extend transversely of the conn~ctor, generally perpendicular to the direction that : the connector and i-ts lead wire would normaLly be moved when being placed on or removed ~rom th~ electxode. '.Fhat is, the pull of the weight or load of the connector i9 generally perpendicular to the an~led e~ge and ~houlder.
Thi8 enhances the ~rip of the connector on th~ electrode.
In addition, the tab is urther gripped between the tips o~ the upper and lower jaw~ 1 and ~ and between the contact tip 32 and the upper jaw plate 34.
~5Another function of the ramps 41 and 42 may be -~ee~
from Figure 6. As the connector jaw~ close, the flexible electrode tab 51 is engaged by the ramps, pullin~ the edgea of the tab down, thereby wrapping ths ~ab around the curved ~urface o the enlarged tip portion 32 of the .30 ~contact 8. Tha ramps are then C108ely spaced from the upper ~urfac~ oE tha lower jaw plat~ 33. Thi~ wrapping in~rease~ th~ Burface area of the el~ctrode engaging ~h~
enlarged tip, improviny the mechanical connectlon w~ile di~tributing the ~orce~ involved. Llk~wisle, the eIect,rical connectlon between the elactrode tab and the contact i~ enhanced by this arranyement, with t.he lower ~2~

g conductive surface of the tab erlgaging the convex, conical ~ur~ace o~ the contast tip. Of cour~e~ good electrical contact 1~ al~o made between the an~led edge 7c and the contact ~houlder 32c. The elec~rical connector does not pierce t~e fragile, ~le~ible electrode, yet the force i8 Rufficient to grip the electrode while maintaining excellent elecl:rical contact.

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Claims (13)

IN THE CLAIMS:

1. An electrical connector for connection to a thin, flexible electrode used in performing electrocardiogram tests comprising:
a pair of pivotally mounted jaws having tips which are biased into gripping position;
an electrical contact supported in one of said jaws having an angled shoulder extending towards the other jaw; and an angled edge portion carried by said other jaw and extending towards said one jaw closely overlapping but not engaging said shoulder so that the thin flexible electrode placed between the jaws is crimped between the shoulder and the edge portion with a conductive surface of the electrode engaging said contact.

2. The connector of Claim 1 wherein said contact includes an elongated body for connection to an electrical conductor, and an enlarged tip which forms said shoulder with respect to the body with said tip extending from said shoulder towards the tips of the jaws at an angle such that the flexible conductor is gripped between the contact and said other jaw.

3. The connector of Claims 2 wherein the angled edge portion is oriented such that when said connector is in a closed position, a wall of said angled edge portion engaging the electrode and the shoulder of said electrical contact are substantially parallel, with the electrode crimped between them.

4. The connector of Claim 3 wherein said jaws have generally plate-like shapes, the angle between said angled edge and the upper jaw plate is approximately 75°, and the angle between the shoulder and the lower plate approximately 90°.

5. The connector of Claim 1 wherein the electrical contact includes an elongated cylindrical portion for connection to an electrical conductor, a tip portion having a convex surface extending towards the other jaw and sloping toward the forward tip of said one jaw.

6. The electrical connector in Claim 1 further comprising a pair of ramps formed on said other jaw extending downwardly toward said one jaw and sloping toward the forward tip of said other jaw.

7. The electrical connector of Claim 6 wherein said ramps are located along the edges of said other jaw and extend towards said one jaw further than said angled edge carried by said other jaw, so as to prevent interference between the flexible electrode and said angled edge when positioning the connector jaws on the electrode.

8. The electrical connector of Claim 2 wherein said enlarged tip has substantially a frusto-conical shape extending towards the other jaw.

9. The electrical connector of Claim 8 wherein the lower surface of the upper jaw is in close proximity to said contact shape when the jaws are closed so that the electrode is pressed into engagement with the contact shape.

10. The connector of Claim 1 wherein the tips of said jaws engage said thin, flexible electrode to aid in gripping the electrode.

11. The electrical connector of Claim 1 in combination with a flexible and disposable electrode for providing electrical contact between the human body and an electrocardiograph to produce electrocardiograms.

12. An electrical connector for connecting a thin, flexible, disposable electrode to the lead wire from an electrocardiograph machine comprising:
a pair of pivotally mounted jaws made of lightweight, electrically insulating material and having a generally plate-like configuration;

spring means urging the rear portions of the jaws apart and urging the tip portions of the jaws into contact with each other;
an electrical contact including an enlarged tip portion positioned in a recess in one of the jaws with a frusto-conical portion extending towards the other jaw, and with the frusto-conical surface tapering toward the forward tip of the jaw;
an angled edge portion on the other jaw extending toward the contact tip, the angled edge portion being located to overlap with, but not engage said contact shoulder so that a tab on said flexible electrode to be received between the jaws is crimped between the angled edge and the contact shoulder; and said other jaw having depending ramps formed thereon that extend toward the jaw containing the contact, the ramps located along the edges of said other jaw to straddle the contact tip portion to wrap the flexible electrode around the frusto-conical surface of the contact tip, said ramps being tapered rearwardly and toward the contact jaw sufficiently far such that the ramps guide the jaws onto the flexible electrode and prevent the electrode from catching on the angled edge.

13. The combination comprising:
a thin, flexible electrode having a thin, electrically-conductive layer positioned on a thin, flexible backing layer; and a lightweight electrical connector gripping an edge portion of the electrode, said connector having a pair of movably-mounted jaws of insulating material having tips which are biased into gripping position on the electrode, an electrical contact positioned in one of the jaws extending towards the other jaw and having a portion for connection to an electrical lead wire, and an angled edge portion carried by the other jaw and extending toward the contact, the edge portion being closely adjacent to and in overlapping relation with the contact but not engaging the contact, with the flexible electrode being crimped between the angled edge and the contact, with the conductive surface of the-electrode being held in firm engagement with the contact.