US1540585A - Electrical stethoscope - Google Patents

Description

June 2, 1925. 1,540,585

R. B. ABBOTT ELECTRICAL STETHOSCOPE Filed Oct- 27. 1922 A TTORNEYS Patented Jane 2, 1925.

UNITED STATES RAYMOND BARRINGTON ABBOTT, F WEST LAFAYETTE, INDIANA.

ELECTRICAL STETHOSGOPE.

Application filed October 27, 1922. Serial No. 597,497.

To all whom it may concern:

Be it known that I, RAYMOND B. Annor'r, a citizen of the United States, and a resident of West Lafayette, in the county of Tippe-' canoe and State of Indiana, have invented a new and Improved Electrical Stethoscope, of which the following is a full, clear, and exact description.

This invention relates to electrical stethoscopes. I In contemplating the invention, consideration must be given to the fact that in using an instrument of this sort the beats which are generally measured are thoseof very low frequency, and it must necessarily be understood that the ordinary electrical de vice for transmitting sound, such as a telephone transmitter, is not especially adaptable to use as a stethoscope because the diaphragm of such transmitter is tuned to frequencies far different than those which are measured when using an ordinary stethoscope. If, therefore, an electrical sound transmitter device, such as an ordinary telephone transmitter, particularly an especially sensitive one, is properly treated it can be made to respond to vibrations or variations in sound produced within a narrow limit of frequency ranges; therefore, it can be and has been tried, in accordance with my invention, to make it respond only to those vibrations which are within the range of those corresponding to the frequency of vibrations of the heart action in the human body. If the transmitter can be tuned to this type of frequency, then it is true that other sounds occurring in the immediate vicinity of the instrument are not received clearly if at all.

To this end, therefore, my invention has for an object the provision of a telephone transmitter with the vibrating parts so arranged and constructed as to be responsive with a high degree of sensitiveness to low frequency vibrations, such as those produced by the heart beat, and to be practically nonresponsive to any other frequencies of beats.

Another object is to provide an electrical sound-receiving device, such as a telephone transmitter, modified by the application thereto of my inventive idea, the application of which to the transmitter, however, does not involve any such change in the transmitter as will require its being rebuilt or redesigned. In other words, my inventive idea can be readily applied to any ordinary telephone transmitter of a degree of sensitiveness suitable for the requirements of the work.

The invention is illustrated in the draw- 1ngs, of which- Figure 1 is a section taken through the transmitter.

Figure 2 is a section taken on the line 2-2 of Figure 1.

The form of the invention shown in the drawing is a preferred form, although it is understood that modifications in the construction and arrangement of the parts and in the character of the materials usedmay be adopted without departing from the spirit of the invention.

'As illustrated in the drawings, the preferred form of the invention includes a cupshaped metallic casing 1 having a central aperture 2 into which the usual mouthpiece 3. preferably of hard rubber, is screwed. This mouthpiece, in the operation of the device in accordance with my invention, is provided with a plain thin diaphragm 4, preferably of some material such as hard rubber or celluloid. Thisdiaphragm may be fastened to the end of the mouthpiece by any suitable means, such as adhesive. The metallic casing 1 has a back plate 5 screwed thereto. This back plate provides a support for a plurality of stub shafts such as 6 and 7 supporting resistance cells 8, preferably containing material such as 9, which may be and generally is loose in granular carbons. These cells with the contained carbon are similar to the ordinary telephone transmitter buttons The resistance to the flow of current through the carbon is varied as the pressure upon the carbon granules is varied. The ends of the cells 8 are connected to a diaphragm 10, preferably made of thin metal, brass or aluminum. This diaphragm is held in the metal case 1 by means of felt washers 10 disposed on either side and held in place by a metal ring 10*. This ring and these washers are held in the casing by being disposed between its front wall and the back plate 5. The center of the back plate 5 is apertured to receive a hard rubber screw lug 11 to which a connection 12. is made by wire 13 to the diaphragm 10. and then back through the buttons or cells 8 to the back plate 5, to a wire 14, which may be connected to a suitable devicesuch as a battery 15 in circuit with which is a primary 16 of a transformer, the secondary 17 of which is connected by wires 18 and 19 to any suitable electrical device 20, which may be a receiver or an amplifier. The battery 15 is connected by a wire 21 to a pin 22 extendin through the screw plug 11. The back of the metallic casingl is covered and the parts exposed thereon are enclosed by a thin metal shell 23 fastened to the casing by any suitable means, such as aset screw 24.

In order to provide that the diaphragm 10 shall vibrate only to thosev frequencies which lie within a narrow and desired range, I pass a pin 25 through the central portion of the diaphragm 10 and on this pm I dlspose a plurality of washers 26, preferably of lead, so as to weight or'load the diaphragm 10. This loading of the diaphragm will slow down the sensitiveness of the diaphragm to other vibrations than those of low frequency.

It will thus be seen that in the transmitting device above described there is an air chamber to the left of the diaphragm 10 containing the carbon buttons and a dead air chamber to the right of the diaphragm 10 and between it and the diaphragm 4 into which the load elements, such as the pin 25 and the washers 26, extend. The pin or bolt is preferably formed of brass. As the thin diaphragm a is placed against the organism, the movement or vibration of which is to be measured, the air within the chamber contained between this diaphragm and the diaphragm 10 will be moved by the movement of the diaphragm 4 and cause a movement of the diaphragm 10 which is regulated or limited by the depression of the weight in the form of the plurality of washers on this diaphragm. Therefore, the loaded diaphragm will respond to the particular vibrations to which it is sensitive and will so affect the carbon cells or buttons as to cause a variation of current in the circuit which may be received or amplified as desired.

What I claim is 1. In an electrical stethoscopic device, means for providing a dead air chamber, a thin diaphragm forming one end wall of the dead air chamber said diaphragm being mounted for free vibratory motion and adapted to freely transmit vibrations to the dead air chamber, a weighted diaphragm forming the other end wall of the chamber, and means whereby vibrations of the last named diaphragm may be converted into electrical signal currents.

2. An electrical stethoscopic device which includes a sound chamber, a thin diaphragm across one end of said chamber, a metallic diaphragm disposed across the other end of said chamber, rod extending through said diaphragm into said chamber, and a plurality of weights disposed on said bar to vary the sensitiveness of the diaphragm to vibrations produced in the chamber by the vibrations of the first mentioned diaphragm when placed against a vibrating organism.

RAYMOND BARRINGTON ABBOTT.

Images