US3307650A - Diaphragm mounting for stethoscope - Google Patents

Description

. March 7, 1967 w. IL. HOWELL 3,307,650

. DIAPHRAGM MOUNTING ,FOR STETHOSCOPE Original Filed Feb. 5,

1963 3 2 Sheets-Sheet 2 3,307,650 DIAPHRAGM MOUNTING FOR STETHOSCOPE William L. Howell, Washington, D.C., assignor to Taylor Instrument Companies, Rochester, N.Y., a corporation of New York Original application Feb. 5, 1963, Ser. No. 257,361, now Patent No. 3,157,246, dated Nov. 17, 1964. Divided and this application Apr. 15, 1964, Ser. No. 360,803 1 Claim. (Cl. 181-24) This application constitutes a division of my pending application Serial No. 257,361 filed February 5, 1963, now Pat. No. 3,157,246.

This invention relates broadly to the art of auscultation, and in its more specific aspects it relates to a stethoscope and the diaphragm mounting thereof whereby the tautness of the diaphragm may be adjusted to vary the frequency response thereof; and the nature and objects of the invention will be readily recognized and understood by those skilled in the art to which it relates in the light of the following explanation and detailed description of the accompanying drawings illustrating what I at present believe to be the preferred embodiment or mechanical expressions of my invention from among various other forms, arrangements, combinations and constructions, of which the invention is capable within the spirit and scope thereof.

My invention has been particularly designed for use with medical stethoscopes for examining the heart, lungs, etc., and, as in conventional stethoscopes provides a diaphragm, membrane or vibrating disc which is caused to vibrate by the sounds of the heart or other organ and thereby produces sound waves which are carried through tubes to the ears of the examiner.

In the medical field it has now been determined that most sounds produced by the heart are of low frequency, however, it has also been established that the sounds produced in the case of aortic insufiiciency and in certain pulmonary disorders are of high frequency.

The behavior of a diaphragm depends upon its thickness, the material with which it is made, and such behavior also depends upon the tautness of the diaphragm.

Efforts have been made to provide diaphragms which will mask the low frequency signals while responding to and reproducing the high frequency signals. Such attenuation is said to be attained by the Bowles stethoscope which provides a relatively rigid diaphragm of relatively substantial thickness to make the high frequency sounds better audible to the human car.

It is known that the masking of low frequency sounds increases proportionally to the thickness of the diaphragm.

Prior to my invention, as far as I am aware, all efforts to provide a stethoscope which will make high frequency sounds audible have been based on diaphragm thickness and materials of which the diaphragm is made, so that no stethoscope is presently available which is capable of picking up sounds of varying frequency so that the normal low frequency sounds and certain high frequency sounds are clearly audible by the use of one instrument, having a single diaphragm. 1

I have discovered that by using a diaphragm of uniform thickness and tensile strength which may be formed of a suitable plastic such as mylar, or shim stock, such as steel, the low frequency and high frequency sounds may both be audible depending upon the tautness of the diaphragm. The diaphragm may be tightened or loosened to operate at the same frequency as the sounds being picked up for clear audition thereof.

In implementing my concept I have devised a stethoscope having unique means whereby the tautness of the diaphragm may be varied in order to obtain the aforemfg mun... as ure. I

mentioned highly desirable results. Such'adjusting means are simple to operate and give to the examining physician a substantially larger scope of audible sounds than has heretofore been possible with one instrument.

In contra-distinction to the single optimum frequency of a violin string, multiple optimum frequencies are inherent in a diaphragm, and the location of such optimum frequencies on the frequency scale may be altered by a change in the tautness of the diaphragm asprovided by my invention.

My invention is not only useful with conventional stethoscopes, but is also useful in demonstrations and the like to large 'or small audiences where mechanical diaphragms are used on electronic amplifiers to obtain opti mum volume.

The means which I have developed for adjusting the tautness of the diaphragm or membrane do not add substantially to the cost of the instrument and are not of a complex nature and have high life expectancy under normal use conditions.

With the foregoing general objects, features and results in view, as well as certain others which will be apparent from the following explanation, the invention consists in certain novel features in design, construction, mounting and combination of elements, as will be more fully and particularly referred to and specified hereinafter.

. Referring to the accompanying dawings:

FIG. 1 is a vertical sectional view of the microphone head of a stethoscope showing the diaphragm assembled and in readiness for clamping to the desired degree of tautness.

FIG. 2 is a view similar to FIG. 1 with the diaphragm in one of its adjusted stretched positions.

FIG. 3 is a vertical sectional view of a further form of my invention illustrating the microphone head of a stethoscope with the diaphragm assembled with the head and in readiness for clamping to the desired degree of tautness.

FIG. 4 is a view similar to FIG. 3 illustrating the diaphragm clamped between the pair of stretching rings.

In the accompanying drawings, and particularly FIGS. 1 and 2 thereof, I have disclosed a head of a stethoscope as comprising the usual bowl which I have designated in its entirety by the numeral 1. This bowl is of generally conical shape having an outer annular flange 3 which is externally threaded as at 5, and is formed with a tube 7 extending from the annular flange 3. As is well understood in this art, the tube 7 communicates with a pair of tubes (not shown) the ends of which are adapted for placement in the ears of the examining physicion. The outer surface 9 of the flange 3 provides a plane surface which, as will be explained hereinafter, functions as a bearing surface in the diaphragm adjusting operation.

I providea clamping ring which is designated in its entirety by the numeral 11. This clamping ring consists of an annular skirt 13 which is internally threaded as at 15, and from the outer endof the skirt 13 an inwardly extending flange 17 is provided, the under portion of the flange 17 presenting a plane surface 19. On the opposite or outerisurface, of flange 17. I fixa ring ofplastic; 21- which upstands from the flange and may be caused to adhereto the flange by any suitable means, The purpose of this plastic ,annuluswill be. explained hereinafter.

The diaphragm 23 comprises a disc of uniform thickness throughout and having tensibility so that the tautness of the diaphragm maybe varied by the unique adjusting means which I have devised. The diaphragm or membrane 23 is preferably formed of a plastic such as Mylar, or it may be formed of steel shim stock and is preferably of a diameter less than the diameter of the skirt 13 of the clamping member or ring 11;

The diaphragm 23 is held in assembled position and is stretched to vary its degree of tautness by means of a washer 25 and a cam ring 27, the washer and ring preferably being of equal diameters and formed of any suitable material, such as metal, having a degree of resilience. The washer 25 is formed with plane or flat upper and lower surfaces 29 and depending from the washer adjacent to but inwardly spaced from the periphery thereof is a continuous tooth 31. As will be apparent from consideration of the drawings, the washer is preferably of less thickness than the cam ring, while they are desirably of the same width, and the diameter of the diaphragm is preferably greater than the CD. of the washer and the cam ring.

The cam ring 27 is formed in its upper surface with a continuous notch 33 which is aligned with the continuous tooth 31 on washer 25 so that, as will be explained, when the washer and cam ring are brought into engagement the tooth will be received in the notch.

The upper surface 35 of cam ring 27 is plane with the exception of the continuous notch 33 and the lower surface of cam ring is formed with an inner bearing surface 37 from which extends radially outwardly and upwardly a camming surface 39.

The various components of my device are assembled by placing the cam ring 27 on the upper surface 9 of the flange 3 of the bowl 1 with the inner bearing surface 37 of the cam ring resting on and supported by the upper surface of the flange. The diaphragm 23' may then be positioned on the cam ring, and the diaphragm may, if desired, be formed with a continuous downwardly depending notch forming a tooth 41 therein which will seat in notch 33 formed in the cam ring. The washer 25 is then laced on the diaphragm and the cam ring with the continuous tooth received in the notches in the diaphragm and the cam ring. The clamping ring 11 is then threaded on flange 3 of the bowl until flange 17 engages the top surface of the washer to clamp the diaphragm between the washer and the cam ring. It will be understood that the diaphragm will be securely locked or clamped in place because of the continuous tooth and the notches on the washer and cam ring, respectively.

With the components assembled, as described, the tautness or stretch of the diaphragm may be increased by screwing the clamping ring further onto the flange of the bowl. When this is done, the flange 17 which engages the washer radially outwardly of its transverse center line and in a line also radially outwardly with respect to plane bearing surface 37 of the cam ring, downward forces are applied to the washer and the cam ring causing them to rock or cam outwardly onto the inclined camming surface 39 of the cam ring, thereby increasing the diametric distance between the inner engaging juncture of the washer and cam ring to cause stretching or increased tautness of the diaphragm for the audible pick-up of high frequency sounds.

It will be recognized that due to the construction of my adjusting means various degrees of diaphragm tautness may be attained and the examining physician may adjust the instrument with great facility during the course of an examination.

The upstanding plastic ring 21 serves as dual function, for it not only ensures that the diaphragm will not come into contact with the human body, but being a relatively poor conductor, it will feel warmer than would the metal when the instrument is applied to the human body during an examination.

In FIGS. 3 and 4 of the drawings I have illustrated a further form of my invention and have used the same reference numerals as heretofore used to describe similar parts. 1

As in the previously described form of this invention, the bowl 1 of the stethoscope is externally threaded as at 5 and the diaphragm 23 is formed of the same material and size as the diaphragm disclosed in FIGS. 1 and 2. The clam-ping ring 11 is formed with internally threaded skirt 13 and with the inwardly directed flange 17' which is of greater width than the flange 17 previously described. The upstanding annular covering 21 is fixed to the flange 17. In this form of my invention I provide a pair of cam rings for clamping and stretching the diaphragm. One of these cam rings 1 have termed the outer cam ring and have designated it generally by numeral 43, while the other cam ring I have termed the inner cam ring and have designated it generally by the reference numeral 45. The upper cam ring 43 is formed with a head 47 having a depending continuous tooth 49 formed thereon. Extending inwardly from the periphery of the head 47 is an upwardly extending cam annulus 51. The inner cam ring 45 is also formed with a head 53 having a depending cam annulus 55 extending inwardly from the periphery thereof.

In this form of my invention it will be apparent that the flange 17 of the clamping ring 11 extends inwardly over the cam annulus 51 so that upon threading the clamping ring onto the threads 5 of the flange 3 of bowl 1, the flange 17 will engage cam annulus 51 and move the head 47 and tooth 49 into clamping engagement with the diaphragm 23 and the head 53 of cam annulus 45. The cam annulus 55 will seat on plane surface 37 of flange 3 and upon further screwing of clamping ring 11 on the flange 3 lateral forces will be brought into play moving the camming rings radially outwardly to thereby stretch or increase the tautness of the diaphragm 23 to provide for the picking up of sounds of increasing frequency. In this form of my invention I also use cam rings of spring metal to obtain the desired results.

I claim:

A head assembly for a stethoscope including a bowl, a diaphragm adapted to be stretched thereacross, and means clampedly engaging said diaphragm and mounting it in operative position, said means including a pair of rings rockably supported on said bowl and at least one of said rings being a cam ring and said diaphragm being positioned between said rings, and a clamping ring adjustably mounted on said bowl and including a radially inwardly extending flange adapted to engage one of said rings and exert pressures thereon to lock the diaphragm therebetween, said cam ring having a cam surface thereon operable to rock said cam ring and the other ring radially outwardly for stretching the diaphragm, and said flange engaging said one of said rings radially outwardly with respect to the transverse center thereof to cause said rocking of the rings.

References Cited by the Examiner UNITED STATES PATENTS 1,799,162 4/ 1931* Goldschmidt 179--181 1,857,794 5/1932 Smythe 181-31 FOREIGN PATENTS 24,27 8 1/ 1912 Great Britain. 75,389 9/ 1932 Sweden.

RICHARD B. WILKINSON, Primary Examiner.

LEO SMILOW, STEPHEN TOMSKY, Examiners,

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