US1604344A - Phonographic apparatus and method therefor - Google Patents

Description

E. GRISSINGER PHCNOGRAPHIG APPARATUS AND METHOD THEREFOR Filed May 2'7, 1918 Patented I Oct. 26 1926.

. UNITED STATES PATENT OFFICE.

ELW 00D GRISSINGER, 0F BUFFALO, NEW YORK, ASSIGNOR TO LUOY ASH GBISSINGER,

' OF BUFFALO, NEW YORK.

PHONOGRAP HIO APPARATUS AND METHOD THEREFOR.

Application filed May 27, 1818. Serial No. 288,734.

My present invention .is shown as embodied in phonographic apparatus which is primarily adapted for recording sound upon a wax or other impressionable surface. An important object of my invention is to insi'ire faithful translation of speech waves or other variations having similar frequencies or similar complexities, into correspondingly varying movements of a lever or other machine element. The specific purpose in view is utilizing the said physical movements for mechanically tracing or cutting an outline or profile having physical inequalities corresponding faithfully to the original speech vibrations, but certain features of my invention which contribute to this object are capable of useful employment in other instruments wherein faithful execution of complex or high frequency waves or movements is necessary or desirable.

In phonographic work, whether recording or reproducing, the widely varying frequencies'as also the complexities of speech waves, should be represented only by the rapidly varying rates of speed and frequency of simple to-and-fro physical movements of the vibratory system,.and to secure more faithful response toand transmission of such waves, the tone arm or lever should execute and transmit the physical movements correspending .to each and all of the component frequencies with equal efliciency and without disproportionately amplifying or diminishing any of them. In my companion aplication of even date herewith, issued as atent No. 1,480,203, Jan. 8, 1924, Iv have shown and described means whereby disroportionate am lifying may be avoided y constructing t e vibratory system so as not to have an pronounced natural frequencies correspon ing to the important frequencies of speech.- This is effected by predetermining the weight, stiffness and elasticity of the vibratory system so that it will have a single natural frequency lower than any of said speech frequencies, and so that the natural frequencies of the elastic elements being too high and of too small total energy to be noticeable in the re roduced sounds. In said application, I ave also shown how damping may be limited mainly to factors WhlCh will operate substantially equally with reference to all of the frequencies involved. These features are of peculiar advantage and novelty for the practice of'55 my present invention for the reasons ex plained below and may be properly claimed in combination therewith, but my present invention concerns more particularly another damping factor which is phonographic recording.

According to present practice, the stylus used for cut-ting the wax record from which the master record is made is caused to mold or cut a spiral groove in the wax, external 5 power being applied through suitable mechanism to produce such movement and trace such groove independently of the energy of the sound waves. The sound waves, however, are required to do all of the work of vibrating the stylus transversely of the spiral groove to produce the sound wave record. The sound waves impinge directly upon a diaphragm, the to-and-fro movements of the diaphragm force corresponding 7 movements of one end of a pivoted lever and the other end of the ievei' carrying the sharpened stylus molds or cuts corresponding physical undulations in said spiral groove. These undulations, whether lateral as in the Victor talking machine, or vertical,v as in the Edison phonograph, constitute the record of the original sound. The fidelity of the record and of the sound to be repro- .duced therefrom, will depend upon how accurately the movements of the sharpened point reproduce the changes of frequency and amplitude of the sound waves impinging upon the diaphragm.

The recording operation is not materially v different where the movements of the stylus lever are caused by telephonic waves acting on an armature instead of airwaves acting on a diaphragm. In either case the wave energies are elastically or non-positively applied and the amplitudes and velocities of transverse movement which they can impart to the stylus will be limited and modified by the nature and extent of the various oppositions or resistances (damping facpeculiar to 60 tors) which oppose the transverse 'movements. hese damping factors include the frictional and other resistances to transverse cutting or molding of the material of the record by the stylus.

The friction is considerable because considerable pressure, usually a dead-weight or gravity pressure, is necessary to maintain the stylus in intimate engagement with the wax or other impressionable material. For the same a'eason the spiral groove is necessarily of considerable depth and the work to be done in transversely molding or cutting the material of the groove is correspondingly great.

These damping factors operating in opposition to all transverse vibrations of the lever have different values for different frequencies, velocities and amplitudes of the transverse movement. Consequently, this kind of damping distorts some frequencies and obliterates others, particularly the overtones or high frequency components of complex waves. As aresult, the tone pitch is greatly modified, the quality of the sound is not faithfullyreproduced and nasal or metallic sounds and noise effects become objectionably prominent.

My present invention contemplates decreasing the above descr'ibed eHects of damping by putting the stylus in a state of continuous rapid vibration transversely of the spiral groove,by energy derived from a source independent of the sound waves to be recorded. The outside energy does the work of overcoming transverse friction, and of transverse molding or cutting of the groove. -This being the normal continuous operation of the apparatus, the work to be done by the sound waves will be merely that of shifting the field of the transverse molding or cutting operation which is being independently maintained by the outside source of power. As a result, the transverse shifting due to the sound energy will be proportionally greater for all frequencies involved, and that due to the minute energy of the overtones and high frequency components will be more nearly proportional to the energies thereof, instead of being disproport'ionally damped out as in prior practice. Hence such nasal and other disagreeable sounds and noise effects as are due to unfaithful distorted recording are eliminated. but the method being essentially one of faithful recording of any and all applied energy which reaches the stylus, it necessarily follows that noises and disturbances whether externally or internally originated, are also faithfully recorded on V the record.

The continuous transverse vibration referred to must be uniform and the rate of vibration such that the sound waves reproduced therefrom will not impair the quality or character of the sound waves to be recorded. The auxiliary energy suitable for this purpose may be a high frequency alternating current of pure tone quality, having a periodicity preferably somewhatin excess of 10,000 periods per second. The amount. of this energy, though small may be and preferably will be greater than the energy of the sound waves to be recorded.

The frequency of the auxiliary energy may be varied within quite wide limits. The principal resonant frequencies of the vowel sounds are below 1,000 periods per second. Sound waves in air are seldom distinguishable above 16,000 periods per second and the louder components are below 5,000 per second. This is particularly true of sound waves coming from the megaphone or horn of a phonograph. W'hile frequencies of 8,000 to 10,000 periods or more may be employed, the requirement is only that the periodicity be such that-when recorded and reproduced, it will not evidence itself as a predominant or objectionable tone.

The frequency may be well Within the recognized limit of audibility but if it is a perfectly uniform tone and not of too great volume, it is not necessarily objectionable. The ear very quickly becomes adjusted to such a condition and a pure continuous tone will pass unnoticed. In certain cases. I take advantage of this fact to employ a frequency and amplitude which will give a tone, which though very noticeable when the attention is directed to it, is ordinarily unnoticed. Such a tone may serve as a highly desirable substitute for the intermittent or non-uniform scratchy tones and metallic qualities which in prior devices frequently cause annoyance to the hearer.

Alternating current generators useful for my purpose'have been designed and constructed giving frequencies much above 30,000 "pulsations per second. Moreover, they have pure tone, that is, sine wave 110 forms. Transformers, electromagnets and armatures forsuch high frequencies are also well known and may be employed. The practical difficulties and the expense will be less, however, and the phonographic re- 115 sults not prohibitively inferior, where frequencies of 10,000 to 7,000 or even lower, are employed or Where vacuum tube or other frequency changers are used in place of the special alternating generators.

Imparting to the vibratory system continuous vibrations of even the lowest of the above frequencies will have a tendency toexcite all parts of the system to local or segmental vibrations and to develop and 125 magnify rattles and other noise-generating activities atfevery. weak point in the system; hence the advantage and invention involved in utilizing for practice of my present invention the noise-free vibratory system such as disclosed in my said companion application. While a vibratory system of the structure herein disclosed embodies the required qualities in a desired form, it is evident that specificall difi'erent constructions may be devised havlng the same qualities.

The apparatus and also the method constituting my present invention may be more fully understood from the following description in connection with the accompanying drawings, inwhich-- Figure 1 is a face view of a sound box adapted to be used as a recorder for the practice of my present invention;

Figure 2 is a vertical central section showing a simple embodiment of my invention;

igure 3 is a similar section showing a modification; and

' herewith. Such construction may be easily Figure 4 is a detailed view showing the rear end of the magnet coil casing.

In these drawings the sound box comprises the annular ring 1, formed with the inwardly projecting annular flange 2 and back-plate 3. In the recess between flange '2 and plate 3 is clamped the diaphragm 5 of mica or other suitable materia disposed between a pair of rubber cushioning rings 6'.

The annular ring2 is formed on one side with an enlargement 7 adapted to form a solid base support for the mounting of the stylus lever 11. The back-plate 3 is formed with an annular opening 8 through which may be applied the energy of the sound waves to be recorded.

The lever arm 11 is attached to the diaphragm near, although not necessarily at the center thereof, and the op osite end is provided with a cutting or mol ing point 14, which may be of any known or desired form and which ma be detachably secured in socket 12 by bmdin screw 13. The lever 11, may be of any own ordesired construction but is preferably of an aluminum alloy and the long arm may be made light yet very rigid by giving it the ribbed construction indicated in the drawings. The pivotal mounting of the lever may be of any approved construction but as shown comprises two wires 15, 16, preferably steel piano wires. These wires are fixed attheir ends, as for instance by clamps 17, 18 and deflecting posts 19, 20, 21, 22, and are spread apart at their intermediate portions where they engage the lever. The two wires may be symmetrically disposed with respect to the pivotal axis and with respect to the longitudinal axis of the lever and may be stretched to very high tension previous to clamping, as and for the purposes explained in my companion application of even date organized and adjusted so as to have no natural frequencies within .therange of the important frequencies of speech, the fundamental being of course below and the frequencies of theelastic wire above said range, as explained in my companion application.

While the above described construction of sound box, lever and pivotal mounting are highly desirable for my resent purpose, it will be understood that t e broad principle of my present apparatus and method of operation are applicable to any known construction of phonographic recorder or annalogous instrument.

In Figure 2 m invention is shown as applied to a soundliox adapted to record air sound waves directly, that is, the sound waves traveling through the air are collected by a suitable mouth-piece 10, are propagated through passage 8 and impinge directly on apply the vibratory energy in direct alignment with the sound wave energy applied by the diaphragm. In this case the auxiliary energy is that of an alternating current app led throu h an electromagnet. The outer end of ro 22 is formed or provided with a soft iron armature 23, which may be detachably or adjustabl screwthreaded thereon as indicated in igure 2. This soft iron armature projects into a solenoid and closely confronts a pole piece 24 at a point near the center of the solenoid and therefore in the most sensitive part of the field thereof.

The electromagnet is mounted on a supplemental casing 25 and comprises a soft iron shell 26. This shell is slotted as indicated at 27 Figure 4, and is rigidly secured to 25 by an integral flange 28 and the screws 29. The pole piece 24 is screw-threaded in the end of shell 26 so as to be mechanically adjustable inwardly or outwardly and it is adapted to be held in fixed position after adjustment by the lock nut 30.

Within the shell 26 are the solenoid windings for applying the high frequency current for variably magnetizing the pole piece 24 to impart the desired continuous vibratory movement to the armature 23 and through it to the stylus lever 11. These coils areclosed in at the end by the removable annulus 51 which is of magnetic material so as to concentrate the magnetic field close to armature 23. The inner cylinder 52 is of non-magnetic material so as not to short circuit the magnetic field.

One of these windings as 31 is connected to the high frequency source of energy, diagrammatically indicated as an alternating current generator 32, through wires 33, 34 which-preferably include an adjustable resistance 35 whereby the amount of the alternating current and resulting amplitude of vibration of the stylus may be regulated to secure the results hereinabove described.

The high frequency energy though derived from an alternating source is preferably employed so as not to cause reversing magnetism of the electromagnet but only single polarity pulsations of increasing and decreasing magnetism. This may be accomplished by applying, preferably through a separate winding 36, a continuous direct current of suliicient power to keep the magnet continually polarized in one direction.

For this purpose, the winding 36 may be connected through wires 37, 38 and an adj ustable resistance 39 with a source of direct current as for instance the battery 40.

By suitably adjusting the resistance 39 which controls the uni-directional magnetizing current in coil 36 and separately adjusting the resistance 35, which controls the alternating energy in coil 31, the initial attraction of the pole piece 24 for armature 22, as well as the amount of the variation of such attraction, may be made of just the strengths required for giving the best results. The constant initial pull of the magnet upon the armature may be balanced by adjusting the lever 11 along the rod 22 to vary the initial tension of the pivotal wires 15, 16. This tension may be assisted or opposed by buckling of the diaphragm 4 either toward or away from the lever 11.

lVhen the high frequency current traverses its coil 31, the attraction between thearmature 23 and the pole piece 24 is varied in accordance with the wave form and frequency of the alternating current and the opposing spring tension remaining constant, the armature 23 and stylus lever 11, are correspondingly vibrated. Sound waves entering the collecting horn 10 and impinging on the diaphragm merely modify this movement and the wave forms recorded on the wax platen will be a composite of the continuously maintained high frequency vibration andthe complex sound wave vibrations superposed. i

In Figure 3 a simple form of an-all electric recorder is shown. All parts remain the same as before except that the horn for collect ng sound waves from the air has been removed and the coils and shell 26 are substituted in its place. The connection of coil 31 to the high frequency alternating source 35 and the connections of coil 36 to the battery through the resistance 39 may be the same as in Figure 2. The diaphragm, however, no longer serves as the means for applying the sound waves to the lever, its only function being that of an end support and guide for the lever 11 and the armature 23. The waves to be recorded are electrically superposed on the continuous high frequency current producing a composite electric wave form in coil 31 which electromagnetically imparts a correspondingly varying physical movement to armature 23 and stylus lever 11.

Where the waves to be recorded are acoustic air waves they are translated into corresponding electrical waves through the medium of a telephone transmitter diagrammatically indicated at 41. The air waves vibrate the transmitter diaphragm thus varying the resistance of a microphone, and correspondingly varying the continuous current from battery 40 by and in accordance with the undulations of the original sound waves. The resulting electrical or telephonic waves are transferred through induction coil 43 which may be arranged in paral lel with the high frequency generator 32 and connected to the magnetcoil 31 through the same wires 33, 34.

The telephone transmitter is preferably of the type shown in my prior Patent No. 1,198,345, granted September 12th, 1916, and the currents received therein may be amplified by telephonic repeaters of the type shown in my prior Patents Nos. 1,198,213, 1,203,326 or 1,205,618.

WVhile I have shown and described a desirable embodiment of my invention, including a special construction of sound box and special means for giving the stylus lever the desired continuous vibration at the desired high frequency, it will be understood that my invention is a broad one and various changes, substitutions, omissions and additions'may be made without departing from the spirit of my invention.

I claim:

1. In a phonographic sound box and in combination with the vibratory lever thereof, means for superposing on the phonographic movements of the latter an additional continuous musical vibration of such frequenc and amplitude as will not produce ob ectionable effects in the resultant phonographic sound product, said means including an armature on said lever, an electromagnet in operative relation thereto and sources of alternating current and direct current for simultaneously energizing said electromagnet.

2. In a phonographic sound box and in combination with. the vibratory lever thereof, means for superposing on the phonographic movements of the latter an additional continuous musical vibration of such frequency and amplitude as will not produce objectionable effects in the resultant phonographic sound product, said means including an armature on said lever, a continuously polarized magnet in operative re- 7 high frequencyto-and-fro movement in a single plane and means for elastically or non-positively applying complex or high frequency wave energy to cause correspond.-

ing movements of said element in said plane,

in combination-with means including a polarized electromagnet and an alternating current generator for continuously applying uni-directional pulsations for vibrating said element to and fro in said plane at a frequency above 10,000 pulsations per second.

4. In a phonographic apparatus and in combination with the stylus leverthereof, means for vibrating said lever including a magnetic pole-piece rigidly secured thereto, a solenoid electromagnet provided with an axial pole-piece extending approximately to the center thereof and closely confronting said first mentioned pole-piece, together with means for energizing said electromagnet, said means including an alternating current generator of frequency higher than the important frequencies of speech.

.5. In a phonographic apparatus and in combination with the stylus lever thereof, means for vibrating said; lever including a magnetic polepiece rigidly secured thereto, a solenoid electromagnet provided with an axial polepiece extending approximately to the center thereof and closely confronting said first mentioned pole-piece, together with means for energizing said electromagnet, said means including a high frequency generator, a batteryand a telephonic circuit. 6. In a phonograph apparatus and in combination with the stylus lever thereof, means for vibrating said lever includingan'armature in the form of a solenoidal core-piece rigidly secured thereto, an iron clad solenoid magnet provided With a pole-piece extending approximately to the center thereof and closely confronting said first mentioned pole-piece, together with means for energizing said electromagnet, said means including a telephonic transmitter.

Signed at New York city in the county .of New York, and State of New York, this 25th day of May, A. D. 1918.

. ELWOOD GRISSINGER.

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