US1854025A

US1854025A - Method and apparatus for generating and detecting impulses

Info

Publication number: US1854025A
Application number: US714899A
Authority: US
Inventors: Reginald A Fessenden
Original assignee: Submarine Signal Co
Current assignee: Submarine Signal Co
Priority date: 1918-03-23
Filing date: 1924-05-21
Publication date: 1932-04-12
Anticipated expiration: 1949-04-12
Also published as: US1863840A; US1501105A

Description

April 12, 1932. R. A. FESSENDEN 1, 9

METHOD AND APPARATUS FOR GENERATING AND DETECTING iMPULSES ori inal Filed March 2:5, 1918 ml Ill-a Patented Apr. 12, 1932 REGINALD A. rnssn'NmtN, or CHESTNUT HI'LL, mssacnosn'r'rs,

'assrenon. To sun- MABIN'E SIGNAL COMPANY, OF PORTLAND, A CORPORATION OF 1":

Marne!) AND Arr'mrtrs roa GENERATING AND nnrrzcrme uns Original application filed March 23, 1918, Serial No. 224,288. Patent No. 1,501,105, dated July 15,1994.

Divided and this application flledjlay 21, 1924. Serial No. 714,889.

My invention relates to methods and apparatus for generating and detecting impulses;

and more particularlv to producing electrical effects or impulses by mechanical means, and mechanical effects or impulses by electrical means; and still more particularly to the transmission and detection of sounds, more especially telephonic, and phonographic sounds. 1o simplicity, accuracy,-freedom from disturbance, are itsfprincipal objects.

Fig. 1 shows diagrammatically means for producing an electrical indication by mechanically straining a magnetic wire, the strain being produced by sound waves.

Fig. 2 shows diagrammatically means for producing a sound from a piano by the reverse action, i. e. the creating of an-impulse or sound by electrical means. It also shows the p means applied to a piano for producing an electrical efl'ect by mechanical strain.

This application is a division, so far as the parts which are common, of my U. S. application Serial Number 224,288, filed March 23rd, 1918, Patent No. 1,501,105, issued July 15, 1924, and of my application Serial Number 531,166; filed J an. 23rd, 1922, the latter a division of an earlier case. In Figure 1, 6 is a box having two opposite 3o ends formed of the diaphragms 7, 9. The

ends of a' wire 8 are attached to these diaphra'gmsr7, 9', and the wire 8 is preferably made of some magnetic material, preferably very soft iron or nickel. 11 is a magnetizlng' 85 coil for magnetizing the wire 8, and12 is a source of continuous current, though an alternating current source may be used. 10 is a second coil wound over the wire 8 and concentric with 11 and the terminals of thewire 10 are connected with the electric circuits as shown. 9

i 20 is a similar box, 19 being a similar wire,

and'21and 22 similar coils to 10 and 11, and

23 is a source of voltage similar to 12. As

ing but merely for balancing, diaphragms similar to 7 ,9, are omittedin this box.

24 is a source of alternating current and A the alternating current from the upper brush flows up till it reaches the junction ofthe Increased eificiency, convenience,-

1 through the medium in which the box is immuch trouble from atmospheric and disthis box is not used for sending and receiv-' primaries 14, 15, when it divides and one half flows-through the primary 14, the condenser 13- and coil 10, and back again to the other brush of 24. The other half flows through the primary 15, condenser 16, coil 21, to the other brush 0f 24. v In operation the current from the/source 24 flows through the divided circuits, and the. I primaries 14, 15 beingwound so as to act oppositely on the secondary 17, no current is produced in the secondary 17 and. no sound 1n the telephone receiver 18, so longv as the two circuits are balanced. Y

As soon, however, as

a sound travelling mersed strikes the diaphragms 9, 7, the wire 8 is put in vibration and its magnetism is al-' tered and the circuit is thrown out of balance and a sound is heard in the telephone receiver 1 76) While a simple form of magnetic detector is here shewn, I have found that any of the well known forms of magnetic detector used for wireless telegraphy, "for example those invented by applicant, may be used provided that they are re-arranged and their construction. so altered that the compressional waves to be detected set the magnetic circuit in vi.- bration, and consequently I do not limit myself to this specific construction here shewn. I Applicants invention of the wireless telephone (Trans. Amer. Inst. Elect. Eng. July 1908 and U. S. Pat. 706,747, Sept. 29th, 1901) has now come into extensive use, but at'present there is much distortion, both in the pick-up of the sounds'to be transmitted, at the sending station; and in the re roduction at the receiving station; and t ore is 90 turbing noises due to other causes; the loudness of. the sound transmitted varies with the position of the actors'on the stage, in vaudeville and other performances; and when reproduced the sound is loud close up to the loud speaker and fainter at adistance,.in the ratio of thlsquare of the distance; and there is an un-natural quality about the re-production. In the making and re-production of phonograph records sim- '100 than any loud speaker now known to the art).

ilar difliculties are met with, except that in place of atmospheric there is the scratching of the needle.

These, and other difliculties are overcome by applicants area source of sound production shown in U. S. Patents No. 1,277,562, filed Feb. 28, 1917, issued Sept. 3, 1918; No. 1,213,176, filed June 27, 1916, issued Jan. 23, 1917 No; 1,212,202, filed May 12, 1 916, issued Jan. 16, 1917 No. 1,319,521, filed June 8, 1917, issued Oct. 20, 1919, and others, and more especially by the forms shown and described herein and in an application divided herefrom and about to be filed.

In Fig. 2 one form is shewn. Here 40 is the sounding board of a piano, which is constructed in the usual manner, well known in the art, except that between the tuning pegs 41, 42 there is stretched a nickel wire, or one of other magnetgizable material, 43. Upon this is wound a layer of enameled copper wire, 44, so that the whole has the appearance of the ordinary wound piano wire. 23 is a source of current, as before, and 45 is a two way double pole switch for connecting 44 to the receiver when it is desired to transmit the sounds emitted by the piano when played upon in the usual manner; or for connecting to the transmitter when it is desired that the piano should act as a loud speaker (for applicant has discovered that it is possible for a piano to so act, and better 1 The tonogen type where, as shown in Fig. 2, the vibration is produced by the lengthening and shortening of the nickel(or iron or other magnetizable material) wire when its magnetization is altered by the transmitter currents, is especially useful in the case of deaf or partially deaf people, who can be made to hear when such a wire as shewn at 43, 44 of Fig. 2 is held between their teeth and transmitter currents passed. The arm may be otherwise shaped if desired.

The vibration generating elements shewn in Figure 2 are conveniently attachable,

as shown, to any musical instrument as- They may also be.

to a banjo, mandolin, etc. attached to the tops of hotel tables, to plate glass windows, etc. and to reflectors of lamps.

The nickel wire wound with enamelled wire is very convenient, and is convenientlyused doubled so-as to form a complete magnetic circuit. In Fig. 2 the steel sounding board and steel pins complete the magnetic circuit.

Where a stringed instrument is used as in Fig. 2 means may be attached for changing the natural resonant periods simultaneously,

by means well known inthe art. It is advantageous as has been found by applicant, to pick up violin music by a violin used as pick up, and to use a violin as loud speaker, and to use pianos for piano music, though this is not" essential as apiano loud-speaker 'will reproduce voice and violin with aston ishing fidelity. Applicant having discovered that, contrary to the heretofore universally accepted doctrine, consonants, as well as vowels, can be perfectly transmitted and reproduced, by this means, by these instrument-s. Many other uses of the devices shewn will suggest themselves.

It. will be noted that the method herein described and claimed is fundamentally different from any of the previously known methods of utilizing magnetostriction. In the previous methods the magnetism of the core when altered by a mechanical strain only gave one single impulse corresponding to that ma etic strain and if the magnetic strain was ept, on for an hour there would be no further electrical impulse produced beyond that occurring during the fraction of a second while the mechanical strain was being applied. Also the energy of the electrical impulse produced was necessarily only a fraction of the energy of the mechanical stress applied. In applicants method the change in permeability produced by the mechanical strain permanently affects, so long as it continues, the flow of a fluctuating or alternating current in the electrical circuit linked with the fe'rro-magnetic cone. Consequently the variation in the energy delivered by the alternating current persists so long as the mechanical strain is maintained, i. e. electrical impulses are continually produced for it may be hours, so long as the core continues: strained.

-Also the effect is or may be many millions of times greater because in applicants method the energy is not derived from the mechanical stress but from the energy of the alternating current circuit, the mechanical stress merely acting as a throttler or valve turner to govern or determine the amount of the alternating current energy flowing through the circuit.

Applicant has found that a much'increased effect is obtained by making the magnetic core above described out of a single elongated crystal of ferro-magnetic material, both when used as a receiver and as a transmitter, and as a generator, Hi; this is not claimed herein as it is claimed and more fully described in another application.

tions comprising normally balanced electrical circmt, means for .impresslng upon the balanced sections of said circuit alternating current of a suitable frequency, means for unbalancing said circuit by varying the permeability of a magnetic core forming a part of one balanced section by the mechanical forces exerted on said core, and means. associated with said circuit for transmitting said electr cal impulse.

2. A circuit for transmitting electrical impulses in accordance with mechanical vanations comprising a normally balanced electrical circuit, means for impressing upon the balanced sections of said circuit alternating current of a suitable frequency, means for unbalancing said circuit by varying the perineability of a ferro-lnagnetic core forming a part of one balanced section by the mechanical forces exerted on said core, and means associated with said circuit for transmitting said electrical impulse.

3. A circuit for transmitting electrical impulses in accordance with mechanical variations comprising a pair of normally balanced shunt circuits, at least one having a sound responsive current varying device, means for impressing a suitable alternating carrier current upon said shunt circuits, a transformer having balanced primary windings connected one in each shunt circuit and the secondary connected in circuit to transmit electric impulses corresponding to the mechanical variations of the sound responsive device.

4. A circuit for transmitting electrical impulses in accordance with mechanical variations comprising a pair of normally balanced shunt circuits, a transformer havlng a pluwhose permeability is varied by the action of the sound Waves on the diaphragms, and a normally balanced circuit including said sound responsive device and a local alternating carrier current supply whereby the action of said sound responsive device will modulate said carrier current supply in accordance therewith.

8. Means for transmitting compressional Waves, including a casing having a diaphragm at opposite sides, a ferro-magnetic core adapted to receive mechanical stresses correspond-- ing to the compressional waves acting on said diaphragm, and means operated thereby for modulating a local carrier source in accordance with the compressional waves.

REGINALD A. FESSENDEN.

rality of primary windings connected in series in said shunt circuits and a secondary for transmlttlng the electric lmpulses, means for impressing an alternating current on the balanced circuit and means included in one of said shuntcircuits for unbalancing said circuit comprising a sound responsive current varying device having a ferro-magnetic core connected in said circuit.

5. A circuit for amplifying compressional wave impulses, including an electromagnetic sound responsive device having a ferro-magnetic core whose permeability varies in accordance with the compressional Waves impressed on the sound responsive device, a

ing the permeability of oneof them in accordance with the compressional Waves, and means for transmitting the unbalanced component of the electric Wave.

7. Means for transmitting compressional wave impulses, including a sound responsive device having a pair of diaphragms responsive to sound waves, a ferro-magnetic core