US1525182A

US1525182A - Sound transmitter and receiver

Info

Publication number: US1525182A
Application number: US650184A
Authority: US
Inventors: Harvey C Hayes
Original assignee: Individual
Current assignee: Individual
Priority date: 1923-07-07
Filing date: 1923-07-07
Publication date: 1925-02-03
Anticipated expiration: 1942-02-03

Description

H. C. HAYES SOUND TRANSMITTER AND RECEIVER I Fe 3. 1925.

Filed July 7, 1923 FIG. 2.

FIG. 1

NIH

Z s we M MH 0 u a H Patented Feb. 3,1925.

UNITED STAT S PATENT" OFFICE.

HARVEY o. HAYES, or wasnmeron, nis'rrucr or COLUMBIA.

scum) TRANSMITTER AND RECEIVER.

. Application filed July 7,

ments in Sound Transmitters and Receivers,

of which the following is a specification.

. My invention relates broadly to devices for converting sound vibrations into electrlcal vibrations or transferring recelved electrical vibrations into sound vibrations,

and more particularly to a construction of sound transmitter or reproducer with oper ating qualities of great eiiiciency' and designed to eliminate distortion inherent in apparatus heretofore available. One of the objects of my invention isto provide a construction of magnetic sound device which may be employed either as a transmitter or receiver at will and which substantially eliminates distortion of sound.

Another object of the invention is to provide an arrangement of vibrating parts for a sound receiver or transmitter wherein the magnetic driving forces corresponding to the electrical vibrations employed are subjected to a considerable distributed area of the vibrating parts integrating the driving forces throughout an extended area to convert the electrical vibrations into sound vibrations of relatively large amplitude.

Another object of the invention is to provide a plurality of cooperating magnets assembled in a transmitter or reproducer construction whereby relatively large driving forces may be imparted to the mechanically moving parts to secure relatively large amplitude vibration by differential action of the magnets one upon the other. Another object of the invention is to provide a construction. of sound transmltter wherein an amplification of theelectrical vibrations produced by sound waves may be secured within the circuits associated with the transmitter.

A further object of the invention is to provide a practical construction of sound reproducer and transmitter having many advantageswhich 'will be pointed out hereinafter, and which construction is capable of manufacture and assembly at reasonable cost on a quantity production basis.

M stood invention w1ll be more clearly underdrawings, in which:

by reference to the accompanying Figure 1 is a side elevation of my as- 1923. Serial No. 650,184.

sembled sound transmitter and reproducer; Fig. 2 is a cross-sectional view of the sound transmitter and reproducer illustrated in Fig. 1; F1g. 3 is a plan view of the apparatus as illustrated in Fig. 1 looking in the direction of the terminals and adjusting means forming a part of the apparatus;

Fig. 4 is a cross-sectional view taken on line 44 of Fig. 2 illustrating the construction of the mechanically moving arts of my apparatus; and Fig. 5 is a schematic wiring diagram illustratin the circuits employed in my apparatuslw ereby it may function either as a transmitter or receiver.

Heretofore in the art practically all dev1ces for transmitting and receiving sound have been either very insensitive or else they have distorted and destroyed the true quality of the sound in such a way as to make the reproduction unfaithful and unsatisfactory. .Distortion of the sound, both by the transmitter and receiver, is in a large measure due to resonance of the vibrating s stem, which usually consists of a dia- The usual method for overcoming this difiiculty is to design the apparatus such that the vibrating parts are resonant at frequencies well above the sound range through which the apparatus will operate in practice. This requires that a slight displacement of the moving system must bring a large restoring force into play, and under such conditions the device becomesvery insensitive, especially when the design is such that the restoring forces brought into play are due to stiffness of the distorted member or members for then the mass which is required of such members gives so much inertia that it is diflicult to impose forced vibrations on the movable system. Large restoring forces can be brought into play by using light dia- Y hragms or other members under tension ut such arrangements are unsatisfactory for various reasons.

My invention involves a different method for overcoming the resonance defects inherent in sound receiving and transmitting apparatus heretofore available, consisting broadly in making the moving parts so light that they'are readily forced into vibration and with so little restoring force that the fundamental resonance frequency is below the operatin range of sounds and the harmonics can damped out. There are a number of factors to be overcome in apply- 7 struction which will be sensitive over a wide range of frequencies, including among others the following:

(a) Since the restoring forces brought intoplay through a. displacement of the movable members is very slight, these members must be'balanced and their motion produced by reciprocating forces;

(1)) Since the moving members are very light and bring but small restoring forces into play when they are distorted, the members will not move as a whole but will tend to. vibrate only over a region surrounding the point or points where the reciprocating forces are applied. Under such conditions the device can neither radiate or absorb much sound energy and will therefore be inetlicient;

() In many cases the electrical imped- -ance of such devices needs to be several thousand ohms, and therefore, in order tha; the resistance losses should not be high it is necessary to use fairly large coils; v (cl) In case of all receivers of the loud speaker class the electrical input must be amplified greatly, and this requires the use ofcomplicated and expensive auxiliary apparatus.

The construction shown in the accompanying drawings overcomes the factors listed above, as will be hereinafter described.

4 I provide a casing represented by refer v ence character 1 forming a protectlve housing for the apparatus with an annular screw threaded ring 2 at one end and an inwardly turned flange 3 atthe other end, between which the magnetic and mechanical parts of my apparatus are secured. Two ring shaped

magnets

4 and 5 are fit-ted'together by an annular joint 6 forming an annular rim supporting a light unstretched diapiiragm 7 which serves as the movalble memr. This diaphragm is coned except for a small portion of its center at 8 and an annular port-ion about the outer area at 9. This design makes the diaphragm rigid even though it is constructedof thin material and confines its deflection to the annular portion 9. The diaphragm 7 is generally made of non-metallic material and, if made of such material, carries on opposite sides two similar light weight annular rings 10 and 11 of magnetic material, or other suitable construction to provide for magnetic act-ion between the .diaphragm and the magnets. These magnetic rings 10 and 11 are so located with respect to the diaphragm 7 that they bridge the annular pole faces 12 and 13 i of

magnet

5, and 14 and 15 of magnet 4, leaving a small equal air space between each ring and its respective pole pieces. Insulate ed annular rings 23 and 24; bridge the gaps between the

pole faces

12 and 13 and 14 and 15 respectively B reason of the symmetry of the design, the diaphragm is attracted toward each magnet 4c and 5 with equal force, provided the two magnets are of equal strength and therefore the diaphragm is balanced.

It will be noted that the driving force is applied over an extended circular area and not at a point in the center of the diaphragm as has heretofore been the practice. The flexible portion 9 of the diaphragm and position of the driving forces revents distorting the diaphragm at the point where the force is applied and thereby tends to prevent the formation of harmonics. Thetwo

magnets

4 and 5 are permanently magnetized with their like poles opposing, that is, the inside pole of each magnet and the outside pole of each magnet are alike as to polarity. Two separate windings are carried upon each magnet, one winding connecting with the sending or receiving circuit, depending upon whether the apparatus is used for a transmitter or receiver, and the other of which may be left open-circuited or connected through a local microphone circuit for amplifying the telephonic signals. The separate windings on magnet ,4 are indicated at 16 and 17, and the windings on magnet 5 are shown at 18 and19.

As will be more clearly seen in Fig. 5, the

magnet coils

16 and 18 are connected in series, but in such a sense that the current in coil 18 strengthens or weakens its magnet 5 at the same time that the current in coil 16 weakens or strengthens its magnet 4 respectively. In other words, these two

coils

16 and 18 form a differential winding on the device as a whole. This differential principle of winding causes the diaphragm armatures 10 and 11 to be driven back and forth between the pole faces 12, 13, 14 and 15 whenever an alternating current passes through the two

coils

16 and 18, since it causes a variation in the magnetic flux linkage betweenthe armature and the two magnets, increasing the linkage with one magnet and at the same time decreasing the linkage with the other, and vice versa, as the current alternates. The

magnet windings

16 and 18 This apparatus as described functions as I an excellent telephone receiver or as a loud speaker without distortion of the reproduced sound. When

coils

19 and 17 are used by connection to terminals26 and 27 the device may serve both as a loud speaker and a transmitter. Coils 1'9 and 17 are wound in the same sense as are

coils

18 and 16 re spectively, and are connected in series phra m '7.

through a microphone 25, one electrode of which is formed by, or o erated by, the d1a- The micro one 25 is mounted on adjusting rod 28 w ich passes through bushing 29 wherein it may be acted upon by set screw 30 to fix the microphone in the best operating position with relation to diaphragm 7 The object of this arrangement is to increase, or amplify, the driving force on the diaphragm 7. This is accomplished as follows :Any motion of the diaphragm, whether produced by the voice or other source of sound meeting the diaphragm or by a telephonic current traversing the telephone coils, causes the current in the microphonen circuit to vary as a result' of a change in the electrical resistance through the microphone. The sense of the current through the

microphone coils

19 and 17 is made such that any variation in this current brought about by motion of the diaphragm will be such as to amplify the diaphragm movement. In this way the diaphragm can be subjected to large accelerating forces, as is required of a loud speakin telephone, and it can be caused to move agamst high damping as is required of a non-resonant transmitter.

While I have described my invention in a certain specific embodiment it is to be understood that various changes may be made within the scope of the appended claims without departing from the spirit of the invention. I have found that the device 0porates well if the movable microphone electrode is separated from the diaphragm by an air space, thus causing the electrode to be moved by the change in pressure of the intervening air caused by motion of the diaphragm. It is also evident that the method of linking a microphone with a diaphragm in such a way as to utilize the variation of the microphonic current for amplifying the motion of the diaphragm, which is causing the variation, can be applied to other than the balanced diaphragm.

Having thus described my invention, what I claim and desire to secure by Letters Patent of the United States is as follows 1. An apparatus for converting electrical vibrations into sound vibrations, comprising in combination a pair of annular magnets positioned adjacent each other, a setof annular pole pieces on each of said magnets, a diaphragm positioned between said ma nets, and a magnetic annular ring carried by and movable with said diaphragm in a position adjacent said pole faces.

2. An apparatus for converting electrical vibrations into sound vibrations, comprim'ng-in combination a pair of annular .magnets located adjacent each other, annular. pole faces carried by eachof said magnets, a diaphragm positioned between said magnets, magnetic annular rin carried on. said diaphragm adjacent sai pole faces,

-and a conical portion in the center of said diaphragm.

3. An apparatus for converting electrical vibrations into sound vibrations, comprising in combination an annular magnet, a pair of annular pole faces carried by said magnet, and a diaphragm mounted adjacent said magnet havin a magnetic annular ring carried on" sai diaphragm and adjacent said pole faces and a conical portion in the center of said diaphragm."

4. An apparatus for converting electrical vibrations into sound vibrations,,comprising in combination an annular magnet, a

pair of annular pole pieces carried by said magnet, a diaphragm mounted adjacent said magnet, said diaphragm comprising a conical portion adjacent the center thereof and a flexible horizontal portion adjacent the outer edge thereof, and a magnetic ring carried by said diaphragm in a position intermediate said conical and flexible portions adjacent said pole faces.

5. An apparatus for convertingelectrical vibrations into sound vibrations, comprising in combination a pair of annular mag netic frame members fitting one within the other, a pair of annular pole faces carried by eachof said magnetic frame members, a balanced diaphragm positioned between said magnetic frame members, said diaphragm having a conical portion adjacent its center. and a flexible portion adjacent its outer edge and fiat magnetic annular rings carried on each side of said diaphragm in a position intermediate said conical portion and said flexible portion, and windings carried on said magnetic frame members for energizing said magnets in accordance with electrical vibrations whereby said diaphragm functions to convert said electrical vibrations into soundvibrations.

6. In an apparatus for transmitting and receiving electrical vibrations, the combination of a pair of annular magnetic frames fitting one within the other, a pair of anprising in combination a pair of annular magnetic frames, a diaphragm mounted between said frames, said diaphragm comprising a conical portion adjacent its center and a horizontal flexible portion adjacent its outer edge, a pair of magnetic annular rings mounted on opposite sides of said diaphragm in a position intermediate said conical portion and said outer flexible portion, a microphone operatively connected with the center of said diaphragm, a plurality of magnet windings on said frames, said windings being connected in series with said,

microphone whereby sound vibrations directed against said diaphragm cause corresponding current variations through said magnet, windings and said microphone.

8. In a transmitter for sound vibrations, the combination of an annular magnet frame, a pair of annular pole faces carried by said frame, a diaphragm mounted adjacent said frame, said diaphragm having a conical portion adjacent its center and a.

horizontal flexible portion adjacent its outer edge, a magnetic annular ring carried by said diaphragm in a position intermediate said conical portion and said flexible portion, a microphone connected with the center of said diaphragm, and a plurality of magnet windings carried by said magnet frame and electrically connected in series with said microphone.

9. An apparatus for converting electrical vibrations into sound vibrations, comprising in combination a pair of annular magnets located adjacent each other, annular'pole pieces carried by each of said'magnets, a non-metallic diaphragm positioned between said magnets, a magnetic ring carried on the flexible portion of said diaphragm adapted to be acted upon by the pole pieces of the magnets.

HARVEY C. HAYES.