US1605295A - Method of and means for translating sound waves - Google Patents

Description

Nov. 2 1926.

E. SHRADER METHOD OF AND MEANS FOR TRANSLATI NG SOUND WAVES Filed 02m. 11, 1922 Fig INVENTOR James E. Shmdev.

WITNESSES:

/ ATTORNEY Patented Nov. 2, 1926.

UNITED STATES 1,605,295 PATENT OFFICE.

JAMES 'E. SHRADER, 0F EDGEWOOD, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

METHOD OF .AND MEANS FOR TRANSLATING SOUND WAVES.

Application filed October 11, 1922. Serial No. 598,682.

My invention relates to telephone systems and apparatus and particularly to soundwave translating device of an improved type. z y

6 In its broad aspect, an object of my invention is to provide a soundnvave translating device and a .cir'cuitarrangement therefor, whereby sound waves may be faithfully translated into correspondingly modulated electrical energy without impairing the quality, tone and, quantity of the translated energy. v z 1 More specifically, an object of my invention is to provide a translating device which.

is operable inan atmosphere of air, which embodies no moving parts and which is further characterized .by itssimplicity of design, efficiency of operation and lack of complicated adjustments, the several parts of 2 which may be easily made by existing automatic machinery and may be readily assembled with a minimum expenditure of time and of money. w z

The'ordinary sound-wave translating de- 2 vice known as a resistor microphone of the carbon capsule type embodies certain inherent undesirable features well known to those skilled in the art, as, for instance, the employment of a vibratory element which tends not only to introduce distortion, but also to complicate the construction of the transmitter.

In carrying my invention into practice, I provide a sound-wave translating device which is based upon the fact that the amount of ionization in an electrical dis charge contained in a gaseous medium is determined by the pressure of the medium.

In one form of my invention, the translating device comprises a pair of spaced electrodes which are coated --with a radioactive material emitting ionizing radiations and which are shunted by an energy. source impressing a potential thereacross of sufficient value to establish an ionization space current. A repeater device of the threeelectrode type is operatively associated with the translating device to convert the variations in the intensity'of the ionization current with pressure into amplified electrical currents of similar wave form. I

\Vith these and other objects and applications in view, my invention'further consists in the nature, the mode of operation and the details of construction hereinafter described and claimed and illustrated in the drawing, I wherein:

Figure 1 is a diagrammatic-view of one embodiment of my invention;

Fig. 2 is a similar view of a modification. In one form of my mventlon, a soundwave translating device 1 is operatively associated with a repeater amplifying device 2, the latter serving to amplify the effects of the former, all as hereinafter more fully tively low ionizationvoltage, as, for in- I stance, air. Adjacent surfaces of the electrodes 3 and 4 are coatedwith a radio-active substance, 5? as, for instance, uranium,

radium or thorium. Such substances are characterized by the fact that they are continuously emanating high-velocit electrical particles, which sometimes take t e form ofalpha particles. Since the ionization voltage of the medium containing the electrodes 3 and 4 is low in'comparison with the veloc 89 ity of the particles, thespace intermediate the two electrodes 3 and 4 is continuouslym a state of ionization. 'The space intermediatethe two electrodes 3 and 4 may be rendered conducting by impressing a-source 6 of direct-current energy ther'eacross' through conductors 7 and 8, respectively. Since the amount of ionization, which is produced by the rapidly moving charges emanating from the radio-active coatings 5 varies directly with the pressure of the atmosphereenveloping the same, it is seen that the effect of impressed sound waves upon the space-current path intermediate the pair of electrodes 3 and 4 is to corre- '95 spondingly vary the intensity of the ionizing currents traversing the same. The modulated currents traversing the circuit, connecting the electrodes 3 and 4 may be impressed upon the input elements 9 and 11 1' of a repeater device 12 through'a coupling transformer 13, the primary winding 14 of which may be included in the conductor8 while the secondary winding'15 of which is connected to the input elements just mentioned.

A grid biasing condenser 16 having a negligible impedance to currents of sound-wave frequency is included in the grid circuit while a grid-leak'resistor 17 is connected in with the pressure variations.

shunt relation to the grid and filament elements 9 and 11, in order to control the intensity of the negative charges which are accumulated on the grid 9 of the repeater device 12. The tube 12 is also provided with the customary plate 18 and plate-filament circuit 19, the latter including a source 21 of directcurrent energy and a primary winding 22 of a coupling transformer 23. A secondary winding 24 of the coupling transformer 23 may be connected to the input elements of an amplifying device (not shown) or other circuit arrangement employing such modulated energy.

\Vhen sound waves are impressed upon the space-current path between the electrodes 3 and 4, the number of collisions between the high velocity particles emanating from the electrodes 3 and 4 and the molecules of the gas contained in the space therebetween are correspondingly varied. Thus, the intensity of the ionizing currents traversing the space current path is .modulated in accordance The resulting modulated alternating currents traversing the primary winding 14: of the transformer 13 are impressed upon the inputelements 9 and 11 of the repeater device" 12 to cause greatly amplified currents of corresponding wave form to traverse the plate-filament cir cuit thereof. The amplified modulated currents traversing the latter circuit may then be impressed upon other amplifying means (not shown) through the coupling transformer 23, having a primary 22 and a secondary 24.

The arrangement shown in Fig. 2 is distinguished from that of Fig. v1 in the design.

of the discharge electrodes of the translating device. In this figure, the electrodes 25'and 26 comprise a cylinder and a rod, respectively, with the latter disposed in the longitudinal axis of the former. As in Fig. 1,

adjacent surfaces are coated with the radioactive material 5. The operation of this figure is the same as that of Fig. 1.

In operation, my apparatus provides a space-current path having a variable impedance resulting from differences in pressure at successive instants at any point in a propagated sound wave traversing the space between two electrodes in the presence of an ionizing means. It will be obvious, therefore, that the dimensions of the space included between the electrodes should preferably be small, in the direction of propagation of the sound, as compared with the shortest wavelength of the sound.

While I have shown and described a particular means for producing an ionizing stream, as by radio-active substance, it is apparent that other means are applicable to my invention, as by thermal means, or photoelectric means. Moreover, while I have described two specific embodiments of my invention for the purpose of illustrating its principles of operation, various changes and modifications may be made therein without departing from the spirit and scope of my invention. I desire, therefore, that only such. limitations shall be imposed thereon as are indicated by the appended claim or demanded by the prior art.

I claim as my invention:

A sound-wave translating device comprising an electrical circuit including a spacecurrent path between two radio-active electrodes in the air, and means for amplifying the variations in an electrical quantity in said circuit resulting from sound waves in said space.

In testimony whereof, I have hereunto subscribed my name this fourth day of October, 1922.

JAMES E. SHRADER.

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