US2664335A - Stylus for recorders - Google Patents

Description

Dec. 29, 1953 G. GORHAM 2,664,335

STYLUS FOR RECORDERS Filed Jan. 11, 1950 A INVENTOR.

' C760 e Gar/2cm: 36 ii I Q- CM' M Patented Dec. 29, 1953 STYLUS FOR RECORDERS George Gotham, New York, N. Y., assignor to Technicon Cardiograph Corporation, New York, N. Y., a corporation Application January 11, 1950, Serial No. 137,915

8 Claims. (Cl. 346-139) This invention relates to pens or styluses for recording instruments, and more especially, though not exclusively, for direct-writing electro-cardiographs.

It is the primary object of the present invention to provide a stylus which is of such character that it has a substantially flat frequency response, in that it responds uniformly to all frequencies within the range of frequencies of body voltages in the operation of the electrocardiograph.

Another object of the present invention is the provision of a stylus of the above character, which is additionally characterized by its simplicity of construction and its reliability in operation.

It is a yet further object of the present inven tion generally to provide an improved stylus for electro-cardiographs or other recording instruments.

The above and other objects, features and advantages of the present invention will be more fully understood from the following description considered in connection with the accompanying illustrative drawings.

In the drawings:

Fig. 1 is a top plan view of a stylus embodying the present invention;

Figs. 2 and 3 are side elevational and bottom plan views, respectively, of the stylus;

Fig. 4 is an enlarged section taken substantially on the line 4-4 of Fig. 1;

Fig. 5 illustrates perspectively the function of the instant stylus in an electro-cardiograph; and

Fig. 6 is an enlarged section taken on the line 6-6 of Fig. 1.

Referring to the drawings, and more particularly to Figs. 1 to 3 thereof, the reference numeral l0 designates a recording pen or stylus which comprises a blade 12 and a hub M on which the latter is mounted in heat-insulated fashion, To this end, the apertured end of the blade 12 is received on a bushing I8 of any suitable heat-insulating material and rests on a preferably integral collar 16 on the latter (Fig. 4). The bushing 18 is, in turn, received on the hub I4 and rests on a preferably integral end collar 32 of the latter. Received on the bushing 18 in superposition on the apertured end 20 of the blade i2 is a spacer 22 which preferably projects above the adjacent end of the bushing 18. The spacer 22 may be made of the same insulating material as the bushing 18. Further received on the hub 14 is a collar 24 which is provided with a set screw 28. The hub l4 has a tapped hole 30 which is to receive the set screw 28 when the collar 24 is in position to hold the spacer 22, the bushing I8 and the interposed apertured end of the blade I 2 securely against the end flange 32 of the hub M. In the present instance, a pin 34 is driven into the hub M, the bushing [8, the apertured end 20 of the blade l2, and the spacer 22, in order drivingly to connect these parts. Thus, the blade I 2, which during the performance of the instant stylus is heated in a manner and for a purpose hereinafter described, is eifectively heat-insulated from the preferably metallic hub I4 and collar 24 by theinterposed bushing 48 and spacer 22. The hub 14 serves for mounting the stylus H] on an oscillatory operating spindle or shaft 36 of a record-- ing instrument, such as an electro-cardiograph. The stylus may conveniently be drivingly connected with the spindle 36 by the same set screw 28 which holds the collar 24 on the hub M.

The blade [2 is preferably made from one of the metals classified in the metal arts as light metals, such as magnesium, aluminum, beryllium, copper and others. A presently preferred blade is made of a magnesium alloy of the kind identifled by Dow Chemical Co. as FSl annealed, and consisting of 95.7% magnesium, 3% aluminum, 1% zinc and 0.3% manganese. The blade [2 is at its recording end 38 preferably reduced widthwise to form a tip with which legibly to record an electro-cardiogram on a web W of recording material (Fig. 5) in an electro-cardiograph of the direct-writing type, for instance. Accordingly, the blade I2 is heated so that its recording end or tip 38 will leave a visual record directly on the recording web W. The web W may, to this end, be chemically treated paper of a known type on which the visual record is produced when being subjected to the heat of the contacting recording tip 38 of the stylus in the fashion shown in Fig. 5, while the web W is being moved longitudinally in the direction of the arrow A over the narrow edge 42 of a support or anvil 44 in a manner more fully disclosed in my 00- pending applications Ser. No. 762,613, filed July 22, 1947, ser. No. 788,801, filed November 29, 1947, now Pat. No. 2,524,564, issued October 3, 1950, and Ser. No. 74,668, filed February 4, 1949. In order to heat the recording end or tip 38 of the stylus, there is provided on the blade 12, and preferably wound directly on a portion of the recording tip 38 itself, an electric heating coil 50 which has preferably integral leads 52 and 54 that extend rearwardly along the blade l2 to the spacer 22 where they are connected with wires 56 and 58,

of an electro-cardiograph, for instance.

surface of certain paper, comparatively rapid wear of the recording tip of the stylus takes place, manifesting itself in ridges or;- grooves the tip of the stylus on the surface thereof next to the pointed edge of the anvil. or; platen 46, thus impairing the character ofthetrace formed on the paper. To overcome this objection, the recording end or tip 38 of theT instant: stylus. is, as best shown in Fig. 6, provided with a wrapper 49 of any suitable chemically inertmaterial' which is not affected by'the printing material with which the lines on therecording-webare formed; A. satisfactory wrapper material for this. purpose is platinum foil, for instance. wrapper ill may conveniently be held securely-on the recording stylus end 38 in any'suitable way as by the heating. coil 5& which. is wound around the adjacent length. or the Wrapper id. Of course, the wrapper flilzmay be dispensed-with if: the instant stylus: is. used on. record material which does not adverselyafiect the stylus,

To further carryout the objective of a light weight. stylus, the. heating coil. 55 and its leads 52' and 54 are. preferably made from a length.

of light-gauge wire which is preferably glass coated for electrical insulation, or otherwise coated with suitable insulation material which safely withstands the. heat emanating frcm'coil es. Wire known to the-trade as Nichrome has been found suitable for said heating coil. The leads 52 and 54. of: the heating coil 56- are pref.- erably passed from one side-to theopposite-side of th blade i2 through holesfifiand 62 therein,

respectively, and are electrically connected with thewires 5.6 and" 58 in metal eyelets 64 and. 66, respectively, inwhich they are secured by-solders .o in any. other suitableway.

The eyelets. S42 and 66 are provided; in the spacer 22: (Fig. i) and? the. material from: which the. latter is made is-preferably-alsoelectrically .insulating as isalsomember H6. The metallic blade 12. is provided with furtherholes: 68 and it. in. order to clear. themetallic eyelets 6& and

fifihrespectively; The blade l2.,.being made of minimum thickness. in accordance with the ob- .jective of obtaining a stylus of'minimum weight,

is preferably reenforcedby an impressed longitudinal ridge or bead 74.

The instantstylus ifii is'characteristic for'its simple yet sturdy construction, and especially for its light weight which renders it so uniformly responsive to all frequencies. within the range of frequencies of body:voltages in the operation In-addition to the light weight of. the blade 52- itself, the fine Wllfl'Of theheating coil 50 and the-rearward extension of the equally fine wire leads and 5'4. of the latter to theeyeletsor terminals 65 and 66, respectively, further aid in re-.-

ducing. the weight of the instant stylusto a mini- .mum. The passagefof. the relatively-long leads and: 54: of the.- heatingcoil 58 througlr the holes es and (52, respectively, in theeblade l2:sub-

stantially midwaythereofeffectively prevents.

theseleads. from displacement sidewise; on the oscillating stylus.

The:

4 While I have shown and described the preferred embodiment of my invention, it will be understood that various changes may be made in the present invention without departing from the underlying idea or principles or the invention witnm the scope of the appended claims.

Having thus described my invention, what I claim and es reto secure by Letters Patent is:

1. A stylus ifor making a record on heat-sensitive recording material, comprising a metallic blade having a recording end and an opposite apertured; end, a metallic hub having a collar at one end, a sleeve of heat-insulating material surrounding saldhub. and having an end collar i resting against said hub collar, said apertured blade end being-received by said sleeve and restagainst the collar of the latter, a spacer of electrical-and-heat insulating material received by said sleeve and overlying said apertured blade end, a collar secured to said hub and engaging. said-spacer, to holdthe latter in firm. engagement. with a d" p rtures lade end;

a driving connecti n be ween. sai a r u s blade end and said hub, an electricnheating coil electrically insula ingl e ur-m on, and 1 nea exchanee relation with, sa b ade nearh r cording. end thereof: spa l c. elets mounted in a d spacer. above: a ep rtu edblade end, ele ricai y. in ula d" eads 2ildmg from: th n s of. said; c l nt sa dy le i espectively, and current-supply wires ldading into said yelets. cspect ve y. w ems Q I said e v and wires in a ye e re pec ively, b gns l t ically c n ted-,vandsai blade e ng pr vided with aper ures. to ear; the; adiasent" e l t re:- spectively.

r c rd ng sty us a s t or h laim. 1, inzwhich aid le ds and ir n aid.- e ts.- respectively) are ancho ed h latt r;- and. permanently held electrically connected by sol er in the; respective eyelets.

A 1 3 13491: mals nea record 011 heat-s nsitive reco d ng mater a ompr in a m llic; b ade having a. c d ng end. and an opposite ap rtu d means so iatedwith said l de adjacent said apertured end for nounting said ad o s illati n n itsown ,p anas id mean including a member formed of electrical-andheat insulatingmaterial overlying said apertured blade end,- an electricheating coil electrically nsula inelyn ed ndv n e tx ha relation with, said blade near therecprding end thereof, spacedzmetallic eyelets'mountedin said member above saidapertured blade end, electrically insulatedleads extending from the ends of said coil into said eyelets, respectively; and current supply wires leading into said eyelets, respectively-the endsof; said leads and; wires in said eyelets,.respectively, being. electrically con.- nected, and said blade being providedwith apertures to. clear the adjacent eyelets, respectively.

A W S! a -dsfined'in fi. h ein said recording and is constituted bya recording tip formed by a. widthwisereduced. end length of the blade so; as to provide a shoulder between said tip and the remainder of said-blade, and said coil-surrounds a length of said tipand bears a ainst-- said; shoulder.

5. A stylus, as definedinclaim 4, wherein said tipisprovided with a. protective coat of heat. conductive, material which is chemically inert to,.the,.rec 0rding material.

.6 A1 stylus, as defined in claim 5, wherein said chemically inert protective coat comprises a platinum foil wrapper onsaid tip.

7. A stylus for making a record on heat-sensitive recording material, comprising an elongated unitary metallic blad having a recording end and an opposite apertured end, means associated with said blade adjacent said apertured end for mounting said blade for oscillation in its own plane, said means including a member formed of electrical-and-heat insulating material overlying said apertured blade end, an electric heating coil electrically insulatingly mounted on, and

in heat-exchange relation with, said blade near the recording end thereof, electrically insulated leads extending from the ends of said coil, current-supply wires electrically connected to the ends of said leads, respectively, and means to insulatingly secure said lead ends and said current supply wires to said blade adjacent said apertured blade end, said recording end of the blade being formed by a widthwise reduced end length of the latter so as to provide a shoulder between said end length and the remainder of said blade, and said coil surrounding a portion of said end length and bearing against said shoulder.

8. A stylus for making a record on heat-sensitary metallic blade having an intermediate shank, a flat recording tip formed at one end of the shank by a widthwise reduced end length of the blade and a blade mounting part formed at the other end of the shank to mount the blade for oscillation in its own plane, an electric heating coil surrounding said tip and spaced inwardly from the free end of the tip, electrically insulated leads extending from the ends of said coil longitudinally of said shank, and means to insulatingly secure said leads to said blade mounting part, said tip having a shoulder and said coil bearing against said shoulder.

GEORGE GORHAM.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 322,918 Farmer July 28, 1885 1,306,631 Rogers June 10, 1919 1,820,088 Parker et a1. Aug. 25, 1931 1,871,944 Best Aug. 16, 1932 1,901,921 Means Mar. 21, 1933 2,454,966 Faus Nov. 30, 1948 2,474,312 Halpern June 28, 1949

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