US1534148A - Sound-translating apparatus - Google Patents

Description

April 21, 1925.

H. VOGT ET AL SOUND TRANSLATING APPARATUS Filed April 4, 1921 v FH 82.

flNVENTRS:

L/osEPl-l Nassau:

/ /AN$ VOGT 4 770 elvEys Patented Apr. 21,1925,

UNITED "STATES.

r Tr. "Fries.

HANS voefr, or nnnnm-scrronnnnne, m) Josnr nner. Ann JOSEPH massoLLE, or

GRUNEWALD, GERMANY, nssrsnons T TRI-ERGON LIMITED, or zuracn, swan znnnnun.

SOUND-TRANSLATING I APPARATUS.

T 0 all whom it may coqwern:

Be it known that we, HANS Vocr, Josnr ENGL, and J osnrn MASSOLLE, citizens of the German Republic, residingat the'l stBei-lin- Schoneberg, the 2nd and 3rd otGrunewald, Germany, have invented certain new'and "useful Improvements in Sound-Translating Apparatus (for which application has: been filed in Germany, August 2, 1919 Great Britain, January 10, 1921; Italy, January 29, 1921; Sweden, December 31, 1920;1Belgium, December 29, 1920; and .Norway, December 30, 1920), of which the following is a specification.

I The invention relates to improvements in sound translating apparatus, which is particularly usefulfor devices whereby sound .waves are received and cause the production of corresponding electrical currents of aparticularly true and undistorted. character. These acoustically produced electric currents may be utilized in various manners as will be obvious. It will be noted, for example,

' that the form of microphonic apparatus comprising this invention is for various reasons particularly well adapted for the control oroperation of vacuum amplifiers.

The control of electric currents by the power of sound can in addition to being effected by purely mechanical methods granular carbon microphones and the like) he also effected by causing the variations of the sound pressure to act on an are discharge. (Hissing are.) Although the latter method has the advantage that no mechani cal means at all (e. g. diaphragms etc.) are employed. and the distortion of the'form of the sound curve which is always caused by mechanical vibrating bodies is therefore precluded, this method has not been found practical. Among the reasons for this, may be noted, first,'that the maintenance of the continuous arc discharge requires a rather considerable current. Accordingly the alternating current corresponding to the sound vibrations, which current is superposed by the controlling action ofthe sound forces upon the continuous current of the are, is very.

small in proportion to the direct carrying current of the. arc. Secondly, such a discharge, in the free atmosphere, as is present,

for example, in a carbon arc, (known as an independent discharge), has hissing and individual noises of such a nature that these and constitute disturbances.

overpower the very weak speakingcurrents,

These hissing and other distorting noises of the are are caused by a lack of constancy of thedischarge of the arc, this being caused-pre dominantly by the combustion and vaporization of the cathode. An arc discharge is characterized by a great consumption of power, this being explained by the high heating of'the cathode necessary for the ionization of the air in the gap traversed by the arc. With an independent discharge ofv the character of the carbon arc discharge this ionization is necessarily effected by the current flowing across the gap between the anode and the cathode, which current heats the cathode and thus causes the ionization.

By this invention these advantages are obviated; one of its characteristic features consists in producing the ionization of the discharge gap not by the energy of the dischargingior anode current (independent discharge) but by special additional ionization means independent of the anode tension or anode current (non-independent discharge). For such special ionizing means high temperatures, Roentgen rays (X-rays), Becquerel rays (rays from a source of radio activity) and light rays of short wave length..(ultra violet rays, etc),iand chemical processes and the like may be employed. Preferably, however, an .electrically heated metal cathode may be used, the outer surface of which, in a preferred form of the invention,-is prepared with substances which strongly further the ionization.

By the invention a constant electron discharge is caused to pass across a small gap in such a -manner as to produce a comparacharge current, when no sound vibrations are the non-independent received is absolutely continuous, i. e.,-'constant. This may be evidenced by the fact that a highly sensitive indicating instrument, inserted in the anode current circuit, shows nofluctuations ofcurrent at. all, at a time when no soundvibratibns are being received.

When, however, the discharge ap 1S acousti-' cally influenced the said gap ters its resistancein exact correspondence with the sound vibrations. These fluctuations of the resistance in the discharge gap cause the superimposition on the direct current traversing the gap of an alternating current corresponding to the controlling sound vibrations,

and'these fluctuations of current are much larger relatively to the normal current across the gap, (i. e.,' the current when no sound is being received), than is the case with an in dependent discharge, for example, in the case of a carbon arc discharge.

It should also be noted that, in comparison, for example, with the independent-discharge of the carbon arc, the hissing and other foreign sounds present in the carbon are discharge are eliminated because, in ac cordance with the present invention, there is no need of using a cathode which is subject to combustion and vaporization. The

form of cathode which we prefer to use does.

not volatilize in the open air at the temperatures used, itbeing noted that in practicing our invention a comparatively small current traverses the discharge gap, this in contradistinction, for example, to the carbon arc in which a high discharge current is required to efi'ect the ionization of the air or other gas.

The use of the form of the invention, re-

ferred' toabove, in which the sound waves irectly into thedischarge gap, ensures iass d t e production of perfectly originally true,

pure, and undistorted speakingcurrents, i. e., currents corresponding to the controlling sound vibrations, as all oscillating mechanical intermediate. arts are eliminated, and. the distorting e ects of independent discharges of the t pe of the carbo'n'arodischarge are also one away with. There are however other possible forms of carrying out the'invention in which for exam 'Ie the variations'in the resistancev of the-lonized:

discharge gap are dependent on variations ofthe distance apart of the electrodes, in

which case mechanical intermediate and the like are necessary; Also, the degree of ionization of the disc arge gap may also Part8 be varied in acoustic rhythm, that is, in accordance with the controlling sound gvibrations, by causing a strongly. ionized to pass continuously into the discharge and causing the rate at which-this passesinto the ga to-be varied, in acco ance with'the contro ng sound waves.- This-may be ac-' complished, for example, by the use of what is term'ed 'a discharge capsule, i. e., a pas sage through which the ionized gas passes,

and which'has a diaphragm mountedzin itspart. Our'improved microphone or sound translating device is also highly suitable, on account of its ordinarily high internal resistance, for the control of vacuum amplifying tubes. The vacuum amplifying tube also has a high internal resistance which is conformable to that of the microphoneor translating device disclosed herein, and the microphone and amplifier are particularly well adapted to be connected together by aresistance coupling, as shown in the drawings herein. By this means the use 'of a low frequency transformer in the connection to the vacuum tube or tubes may be done away with, and this is an advantage in the use of the form of micro hone described herein in man cases as w en for reasons of clearness 0 speech theuse of the low,

frequency transformers is injurious. This sound vibrations cannot be transmitted with "is 50,, because currents corresponding to clearness and lack of distortion, when low e invention consists in the sou nd translating apparatus described harem, and in frefilliency transformers aroused.

the vanous combinations of elements and.

forms of constructions which are described herein and pended claims.

clearly understood attention is hereby Idi;

rected to the accompanying drawings,illus;-

trating two forms of construction: which may be used, and which are included within J the invention. Y y

In the drawings Fig. 1 represents diagra act directly upon the discharge .current, in

the gap without the-use of any mechanical intermediate parts, and

Fig. 2 is a.v similarshowmg a constructional form in which the sound waves 'strike against and 0 rate a mechanical. oscillating body by w ich the distance between the cathode and mode is controlled.

: Referring first to'Fig. 1 of the drawings the sound waves enter the'funnel, or-sound receiving device t in the direction ofthe arrow, which funnel preferably terminates In] ordercth'at the inventionmay be more mma tically, 5L

which will be claimedin the 'of construction in which the sound "waves diagrammatic View 7 in a fiat nozzle. The funnel, as illustrated, may be ota tapering form to condense the sound waves which pass through the same. The nozzle, at the smaller or inner end of the funnel forms, or carries, the anode a. The anode is placed a very short distance in front of the cathode It, whereas the distance between the electrodes in a carbon arc discharge is relatively considerable. Itis well known that in a carbon arc device the arc cannot be formed andmaintained when the? electrodes are as close together as they are, or may be in an electron discharge type of apparatus of the character here described.

lln the construction shown in the drawings thecathode is heated by battery I). which, as illustrated, is included in series with the cathode in a local heatingcircuit. The anode and cathode together with the dischar e a between them are connected in series in a circuit including the source of potential represented by battery and a suitably dimensioned resistance -21. Battery 12 supplies a high potential drop through resistance u, at the discharge gap. 0. A. This resistance may, for example, be the windings of a telephone receiver or it may for example be a suitable coupling resistance for vacuum amplifying tubes The circuit leading away from the anode-cathode circuit illustrated, in which the acoustically modified current which is desired is to be transmitted. is represented by the wires, illustrated in Fig 1. connected one on each side of the resistance u.v If this circuit is toinclude vacuum amplifying tubes for intensifying the speaking current produced, the resistance 10 should be a proper ohmic coupling resistance for such tubes.

If, now, the cathode be heated by the battery 7:, it ionizes the space between anode a and cathode Z' and an electron discharge takes place between the cathode and anode, with a consequent flow at current across the gap. This. current will begreater or less in strength in accordance with the degree of ionization of the discharge gap and also in accordance with the anode potential and in accordance with the form of the anode, certain forms of anode being more favorable for the distribution of the field to produce a strong current than other forms,-

quite exactly to the sound vibrations will be superposed upon this direct current, as has been stated, this acoustically influenced alternating current being caused by the impingement of the sound vibrations directly upon the discharge gap. It is believed that .this modification of the current flowing across the gap is caused largely by the vibratory motion of the air corresponding to the sound waves, and partly to the pressure induced by the sound waves.

llt should be noted that the path of the sound waves through funnel z, in the construction shown in Fig. 1, is directly in alignment with the lengthwise direction of gap is relatively small.

A similar effect is obtained by the arrangement shown in Fig. 2, in which the same reference numerals are used to indicate corresponding parts. In Fig. 2, however, the funnel t is closed at its inner end by a diaphragm m to which. is mechanically connected the anode a. The sound waves entering funnel t actupon diaphragm m and set the same. into vibration as a result of which the anode carried by the diaphragm moves to greater or less extent towards the cathode is. The resistance of the discharge gap is varied in accordance with the variation indistance between the cathode and anode thus. produced, and the current flowing across the gap and in the anode circuit will accordingly be varied in accordance with the sound vibrations which produce the movement of diaphragm m.

The cathode, as noted above. should be formed of a conducting material which is incombustible, and not volatilizable at the temperatures used, such a material being. for example, a suitable metal. Also. as has been stated, this cathode may be coated with. or its surface prepared with. a material which will tend to increase. when heated. the ionization of the air or other gas in the discharge gap. Such substances are known, such for example as certain oxides of the. alkaline earth metals, such as theoxides of calcium or strontium or barium, which may be used for this purpose.

It should be noted that, in the claims, the statement that. the constant electron discharge across the gap when no sound vibrations are received, produces a comparatively small direct current, should be understood to mean that this current is small in comparison with that which is required to maintain a carbon arc discharge.

It should be understood thatthe invention is not limited strictly to the details of construction which have been particularly described, but that the invention is of a con-.

llo

siderable breadth, and that a wide range of equivalents for the constructions which have particularly been described are included within the scope of the invention.

We claim 1.- Sound translating apparatus, comprising the combination of a circuit including an anode and cathode adjacent thereto with a gas dischargepath between them and a source of potential, ionizing means for said path separate from said source, and means for causing sound Waves to be directed through the -air upon said discharge path to modify the electrical conditions in said path. I 2.. Sound translating apparatus, comprising the combination of a sound receiving member, a circuit including a pair of electrodes with an air gap forming a gas discharge path between them and a source of potential, and ionizing means for said path separate from said source, said sound receiving member and discharge path being adjacent to each other and so arranged that current-flowing along said path will be modified in accordance with the sound vibrations.

3. Sound translating apparatus, comprising the combination of a circuit including' an anode andcathode with an air gap forming a gas discharge gap between them, means for producing a constant electron dischar e across said gap producing a comparative y small constant direct current in'said circuit, said current being insufiicient to volatilize the cathode, and a sound receiving member adjacent to said gap so arranged in relation thereto as to cause sound vibrations received to cause the superimposition on the direct current" in the gap of an alternating current fluctuating 1n accordance with the sound vibrations.

4. Sound translating apparatus, comprlsing the combination of a circuit including an'anode and a non-volatilizing cathode with an air gap forming a gas discharge gap between them, means for producing a constant electron discharge across said gap, producing a small constant direct current in said circuit, said means comprising a source of potential in said circuit and a separate heating circuit for said cathode, and a sound transmitting member adjacent to said gap i so arranged in relation thereto as to cause sound vibrations received to cause the super- 7 prlsing the combination of a circuit includimposition on the direct current in the gap of an alternating current fluctuating in accordance with the sound vibrations.

5. Sound translating apparatus, comprising the combination of a circuit including an anode and cathode adjacent thereto with a gas discharge path between them and a source of potential, ionizing means for said path comprising a separate heating circuit for said cathode, and means for causing sound waves to be directed through a fluid for causing sound waves to be directed en-' tirely'through a fluid medium upon said discharge path in the direction of the path from the anode to the cathode, to modify the electrical conditions in said path.

7 Sound translating apparatus, compris ing the combination of a circuit including an anode and a cathode with a gas discharge gap between them, means for producing a constant electron discharge across said gap producing a comparatively small constant direct current in saidcircuit, and a sound" receiving member extending adjacent to said anode in the direction of the path-from the anode to the cathode, to cause sound vibrameans for producing a constant electron dis,

charge across said gap, modified in accordance with sound vibrations when the same are received by said sound receiving member; i

9. Sound translating apparatus, comprising the combination of a circuit including an anode and a cathode adjacent thereto with an air gap comprising a gas discharge path between them, and a source of potential, means separate from said source for heating said cathode to ionize said gap, said source and circuit being arranged to cause a relatively small current to flow through said circuit-and across said gap, and a sound receiving member leading to said gap, arranged to cause sound vibrations received to modify the electrical conditions in said gap.

10. Sound translating apparatus. coming an anode and cathode adjacent thereto with a. gas discharge gap between them and a source of high volt-a e and a resistance, ionizing means for said gap separate from said source, and a sound receiving member leading to said gap, arranged to cause sound vibrations received to modify the electrical conditions in said gap.

11. Sound translating apparatus, comprising the combination of a circuit including an anode and a cathode with an air gapforming a gas discharge gap between them, the cathode being of metal with an external surface composed of a substance which upon being heated tends to increase ionization in the gap, means for producing a constant 1 election discharge-across said gap producing a comparatlvely small constant direct current in said circuit, said current being insuflicient to volatilize said cathodef and a sound receiving member closely adjacent brations.

12. Sound translating apparatus, comprising the combination of a sound receiving conduit, a circuit including an anode and cathode adjacent thereto with an air gap forming a gas discharge path between them, a source of potential and a high ohmic resistance, suitable as coupling re.

sistance for a vacuum amplifier, an ionizing means for said path separate from said source, said sound receiving conduit anddischarge pathbeing adjacent to each other and so arranged that current flowing along said path will be modified in accordance with the sound vibrations. and output circuit connections connected of sald reslstance. 1 a

13. Sound translating apparatus, comacross the ends prising the combination of a circuit includ- 7 ing an anode and cathode adjacent thereto sound transmitting conduit one end ofwhich extends to and opens directly upon said path.

y 14. Sound translating apparatus, com-- prising the combination of a circuit including an anode and cathode adjacent thereto with a gas discharge path between them and a source of potential, a separate heating circuit for said cathode, and a sound transmitting conduit one end of which extends to and opens directly 'upon said path.

15. Sound translating apparatus, comprising the combination of a circuit including an anode and cathode adjacent thereto with an air gap forming'a gas dischargepath between them and a source of potential, a separate heating circuit for said cathode. and a sound transmitting'conduit one end of which extends closely adjacent to said path, said sound transmitting device being aligned with the an'ode-cathode path.

n In testimony whereof we afix our signatures in presence of two witnesses.

HANS VOGT; DR. J OSEF ENGL. JOSEPH MASSOLLE. Witnesses:

Fnrrz WAMFENDS, Dr. 01130 SCHNEIDER.-

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