US2357026A - Phonograph - Google Patents

Description

Aug. 29, 1944. s. A. SCHERBATSKOY PHONOGRAPH Filed Oct. 30, 1943 4* Alma (MW i'liii V Ii'III! FIG. 5

Patented Aug. 29, 1944 UNITED STATES PATENT OFFICE PHONOGRAPH Serge Alexander Scherbatskoy, Tulsa, Okla. Application October 30, 1943, Serial No. 508,357

(Cl. I'm-100.4)

3 Claims.

This invention relates to phonographicreproduction and more particularly to the picking up and reproducing of oscillations from an undulating record groove. By way of preferred example, the invention has been illustrated and described with reference to grooves undulating laterally, or in the plane of the record surface, but it is to be understood that no unnecessary limitation thereto is intended.

It is an object of the invention to provide a generally improved pick-up device.

It is an object to provide a phonograph apparatus of extreme simplicity, ruggedness and lightness by providing a new type of pick-up device which simplifies considerably the structure of the whole phonograph assembly.

It is an object toprovide a pick-up device of extreme simplicity and ruggedness which operates satisfactorily with a very low pressure of its needle or other stylus against the record. With similar objects in view, a number of pickup devices of this nature have been used in the past. These may be considered as comprising a moving or armature system subjected to vibration by the undulations of the record groove (which will be understood to be moved relatively to the pick-up device), and a translating system responsive to that vibration and serving to translate it into electric oscillations. The translating system may, for example, have a sensitiv portion in relatively close spaced relationship to the armature, the vibration of the armature serving to oscillatorily vary this spaced relationship so to influence the translating system. In another view, the translating may have a. field, for example electrostatic or electromagnetic, in which the armature vibrates, the resulting oscillatory alteration of the field giving rise to the desired electric oscillations.

The pick-up systems heretofore used where mostly of electrostatic, electromagnetic or piezoelectric type in which the translation of the armature oscillations into electrical current utilized the effects of electrostatic or electromagnetic induction or the piezoelectric efiect. It is well known that in the pick-up systems of the prior type the conversion of the mechanical vibrational energy of the pick-up needle into electrical energy took place without the presence of any external sources of energy. Consequently, if we neglect any frictional and eddy current losses, we will realize that the electrical energy derived from the pick-up systems was substantially equal to the mechanical energy of the vibrations of the needle. It is apparent that this electrical energy was too weak to actuate a loudspeaker, and, consequently, in order to provide a successful phonographic reproduction of speech and music, it was necessary to provide electronic amplification in order to intensify the currents derived from the pick-up to a degree required for the operation of a loudspeaker.

Consequently, the phonograph system used in the prior art required an electronic amplifying equipment which rendered the phonographs cumbersome, complicated, anad expensive.

It is a purpose of the present invention to provide new phonographic systems in which electronic amplification is eliminated which combine ruggedness and simplicity with low cost and which,'therefore, possess considerably increased market possibilities. I am accomplishing this purpose by providing the phonograph with a new pick-up device of electrolytic type in which the conversion from the mechanical, vibrational energy of the needle'into electrical energy takes place in presence of a supply of current, such as an electric battery. Consequently, in my new t of, pick-up device, the electrical output is considerably larger than the vibrational energy of the needle and may increase at will by increasing the current supply of the battery. Therefore, the electronic amplification is no longer necessary and the whole phonograph assembly is of a considerable simplicity in design.

It is the purpose of my invention to provide a new type of a phonograph-1c pick-up utilizing an electrolyte and two electrodes immersed in the electrolyte and in which the distance between the electrodes is varied by the vibrations of the pick-up needle. Such a pick-up device will be included in a suitable electrical network energized by a source of electrical energy and across the output terminals of the electrical network electrical currents will be obtained which will correspond to the vibrations of the pick-up needle. It is a further purpose of my invention to provide an improved form of construction of vibrational resistances, of the type referred to. This construction relates particularly to vibrational electrolytic resistances in which the distance between the electrodes can be varied when the device is exposed to the vibrations that it is desired to reproduce.

In general, it is an object of my invention to provide a phonographic pick-up device for translating mechanical vibrations into electrical currents which involves the principle of varying the distance between electrodes immersed in an electrolyte. Such adevice may be constructed in an efllcient and compact'manner similar to well known other pick-up devices for translating mechanical vibrations, into electrical currents. 1

Other objects and advantages of the invention will be apparent from the following descriptions when read in conjunction with the drawing, in which:

Figure 1 is a view, partly elevational and partly cross-sectional, of a pick-up device in which my invention has been embodied together with a schematic diagram of the remaining associated apparatus of the phonograph equipment.

Figure 2 is a cross-sectional view taken along the line 2-2 of Figure 1.

Figure 3 is a cross-sectional view taken along the line 3-3 of Figure 2.

Figure 4 is a cross-sectional view taken along line 4-4 or Figure 2.

Figure 5 shows a modified portion of the phonograph equipment which is energized by a source of alternating current.

Referring now more particularly to Figure 1, there is shown diagrammatically a phonograph system including a pick-up device it provided with a vibratable needle l5 subject to vibration of the record groove I! (which is understood to be moved relatively to the pick-up device). The pick-up device is of a novel type and consists of an electrolytic cell formed by a casing i i, containing a suitable electrolyte l2 and two electrodes submerged in the electrolyte, one of said electrodes being movable and consisting of the needle 55 and the other electrode being stationary and consisting of a metallic spring it which shall be referred to later in the description.

The casing it may be secured at the front extremity of a cylindrical arm 23 with a slight inclination to bring its bottom somewhat more forward than its top. The arm will be understood to b supported at its rear extremity by a support l9. The support l9 renders the forward extremity of the arm free to move up and down forengagement of the pick-up needle i5 with the record I1, and from side to side so that the needle may track a groove in the record :siderably intensified form. The output of the tight to the closure member 3L Through theresilient block 35, for example centrally thereof,

there is provided a very small diameter hole 33.

To the inside of the top of the casing ll there may be secured a metallic block 31 and in the bottom surface of this block, in line with the hole 36 abovementioned, there may be provided a concave conical bearing 38. The armature system oi! the pick-up device comprises the needle ll having the record-contacting point 39 at its bottom extremity and the bearing-contacting point 40 at its top extremity. The needle is simply being pushed upwardly through the hole 36 until its extremity 40 engages the bearing 38. The hole 36 is readily arranged to have a diameter sufliciently small'so that the inserted needle will be securely retained water-tight.

It will be understood that the groove undulations in the moving record I! (with its direction of movement under the needle indicated by the the resilient block 35 in immediate contact therer with). Not only will this frequency inherently be very high, "but also the tendency to excessive vibration due to this resonance is effectively damped by theblock 35; -For this damping action as well as for such damping'action as may be desirable on the intended vibration of the neecontained within the casing H,

network 23 is translated into sound by means of a loudspeaker 30 of a c ventional design.

Referring now more articularly to the pickup device In, the metallic casing H is shown as having a closure member 3| removably secured across its otherwise open bottom. Through the bottom member 3| there is provided a relatively large hole 32; the very top portion 33 of which is made of reduced diameter to provide a shoulder.

In the hole 32 there is retained a circular block 35 of resilient material. While this retention may be insured in any desired manner, I have by way of example illustrated the hole 32 as formed with a slight flange 34 inwardly directly at its bottom; the block 35, compressed during insertion to pass the flange, thereafter expands die, it may be desirable to choose the material of the block 35 to have a significant viscous damping, as well as resilient, characteristic. As an example of an appropriate material there may be mentioned the synthetic rubber currently available as neoprene.

The translating system which I have illustrated is an electrolytic one, basically comprising two electrodes in special relationship one from the other and submerged in an electrolytic solution One of the two electrodes is stationary and consists of the spring IS. The other electrode is the vibratory needle I 5 which with-the stationary one forms an oscillatorily variable electrolyte resistance. As a mounting for the stationary electrode there may be secured to the inside surface of the righthand side of the casing H block 4| of insulating material (such for example as the phenol-resin composition known as Bakelite"), which may extend very nearly down to-the bottom member 31.

Just above the bottom of this block 4| there may be provided a horizontal threaded hole 42 extending in a side-to-side direction through the block, and accessible from outside the casing by virtue of an aligned, slightly larger-diameter hole provided in the casing. In this hole 42 whose axis intersects the needle l5 slightly above the resilient block 35 there may be provided an adjustable screw 43. This screw is employed for the adjustment of the stationary electrode II which is then made electrically independent of the screw (so that, among other things, touching of the screw with a screwdriver for adjustment purposes will not cause undue electrical disturbances). Accordingly, the stationary electrode has a form of a spring it having its upper extremity secured to the inner surface of the block 4! near the top of the latter, extending there- .from diagonally downwardly and toward the needle, and finally curving into a lowerportion essentially parallel to and near the needle. A small pad 45 of insulating material may-be secured on the outer side of spring Ilopposite the end of the screw 43, and the spring It may be tensioned to maintain contact of this pad against that screw end. It will thus be understood that the screw 42 will serve to adjust the spacing of the operatively stationary electrode or spring I8 from the needle or vibratory electrode I5.. In,.

general, this spacing will ordinarily be adjusted to theminimum which still insures failure-of contacting of the two electrodes under conditions of maximum vibration of II.

Preferably the arm will be secured to the casing II so that its axis intersects the needle I5. This may be offset (e. g., to the left) from the center of the casing, in view of the space requirement which exists on the one side for the sta- .tionary electrode and its support, and which has no counterpart on the other side. Any tendency toward side-to-side unbalance, to such extent as 20, through the bearing member 31 which rests" on its upper extremity. Furthermore, the arm 20 is electrically connected through the mounting of the arm Is to the output terminal 22. For

electrical connection to the stationary electrode I6 there may be employed a conductor 41.; this may pass longitudinally through the cylindrical arm 20 whose forward extremity preferably is open into the interior of the casing I I. The portion of conductor 41 within the arm maybe insulated by the usual insulating covering 48. Further, in order that the capacity between it and the arm may be kept both constant and at a minimum, it is preferable that it be held centrally of the arm by a packing 49 of suitable insulating fibrous material or the like.

In considering the action of the structure of the electrolytic pick-up it is convenient to bear in mind that the eiiiciency of the translating system and action is dependent on the spacing of the armature or needle I5 fromv the stationary electrode or spring It and upon the electrolyte resistance of the liquid in which both electrodes are submerged. It is well known that the electrolytic resistance between the electrodes depends upon the resistivity of the electrolyte which is a function of factors such as the nature of the electrolyte, its concentration, etc., and also dependsupon the distance between the electrodes. Consequently under the aforementioned conditions when no vibrations are present the electrolyte resistance between the electrodes. I5 and I6 has a fixed and determined value, because the distance between the electrodes I4 and I8 is fixed and determined.

It will be understood that as the armature or needle I5 is vibrated by the groove undulations, the distance between the needle I5 and the spring gree of unbalance of the bridge.

to vibrations by the undulations of the record groove.

The output leads 2| and 22 of the pick-up device are connected to a Wheatstone bridge circuit 50 which is energized by a D. C. source oi voltage, which is represented by a battery 24. One arm of the Wheatstone bridge consists of the electrolytic resistance inserted between the leads 2|, 22, and the remaining three arms of the bridge circuit consists of resistors 58, 51, and 58.

The battery 24 is applied-between the terminals 50 and BI, the terminal 50 being the point of Junction ,of-the resistor 56 and the lead 22-and the terminal 8| being the point of junction of the resistors 51 and 58. The resistors 56, 51, and

' 58 have been so chosen that when the needle I5 is at rest the ratio of the resistance "to the resistance 51 is equal to the ratio of the electrolytic resistanc to the resistance 56. It can readily be shown that the bridge is balanced, that is, the potential difierence resulting from the source 24 and applied across the terminals 60 andil will cause no potential difference to exist between terminals 10 and II, the terminal I0 being the point of junction of the resistor 58 and of the lead-2|, and the terminal II being the point of junction of the resistors and 51. The terminals 10 and II are connected through the leads25, 26 to the loudspeaker 30.

It will be understood that the groove undulations in the moving record will cause the distance between the needle I5 and the spring I6 to alternately decrease and increase. When the distance decreases, the bridge 50 becomes unbalanced and a'D. C.-voltag appears across the output leads 25 and 26., It'can be readily appreciated that the magnitude of this voltage represents the de- Consequently, when distance between the needle l5 and the spring I6 continues to decrease the unbalance of th bridge continues and the voltage-across the output leads 25, 26 becomes larger. When, however, the deviation of the needle has attained a minimum and then increases by passing through the normal equilibrium position, the voltage across the output leads 25, 26 decreases and reaches the value zero. It is readily apparent that when the needle deviates in the opposite direction, the unbalance voltage across the output leads 25 and 26-appears again with a polarity which is opposite to the one referred to above. Consequently, the polarity of the unbalance voltage appearing across the output leads 25 and 26 represents the left or right deviation of the needle and the magnitude of the voltage represents the magnitude of the deviation.

It is, therefore, apparent that across the output leads 25 and 26, we obtain electrical oscillations which represent mechanical vibrations to which the needle I5 is subjected by the undu1ations of the record groove. These oscillations are subsequently impressed to the loudspeaker 30 7 any other II will vary, and will cause variations in the electrolytic resistance between needle and the spring. Consequently, changes in electrolytic resistance between the connecting leads 2I and 22 will be produced when the needle I5 becomes subjected sistors has been confined thereforeto applications in which these detrimental features were not objectionable or'for which they possessed counter E. M. F. is effective on the electrodes owing to the formation of an oxy-hydrogen element. This counter E. M. F. must be annulled by removing immediately the oxygen when being formed on the electrode. This is possible by reducing the separated oxygen with the aid oihydrogen.

Accordingly, in the present application the polarization is absolutely eliminated by the fact that at least one electrode on which oxygen would deposit or both electrodes, during the passage of the electric current, are brought into contact with a substance which possesses a hydrogen pressure sufiicient to reduce the oxygen depositing on either electrode.

All solid or liquid substances having any partial pressure of the hydrogen are, therefore, suitable for the elimination of th polarization efiect; however, such substances are preferably employed which do not cause any ionic reactions afiecting the conductivity that isto say, substances of neutral molecules having a certain partial pressure of the hydrogen, such as for instance, quinhydrone. Besides, all reduction-oxy-, dation systems which present a partial pressure of the hydrogen are suitable for this purpose such as, for instance, indophenol, methylene blue, etc. Furthermore, electrolytes may be employed such as an'aqeous solution of a mixture of F'eCla and FeClz. Since only very small quantities are,

as a rule, necessary for the reduction of the oxygen, they can be soarranged that the conductivity caused by the addition of such electrolytes may be practically neglected with respect to the conductivity to be measured.

In practice, it has been found that slight traces of quinhydrone which are added to the solution under test, prevent completely polarization when using platinum electrodes. For instance, an amount less than 1 mg. substance is sufficient for one liter of solution. Instead of platinum, also less noble metals, such as gold, silver, iron-nickel alloys, etc. may be employed as substances for electrodes which absorb the oxygen depositing on the electrode in such a manner that the oxygen reacts with the hydrogen of the material added thereto.

The electrolyte to be used in the electrolytic pick-up may also be of the type described in Research paper R. P. 1126, part of the Journal of Research of the National Bureau of Standards, vol. 21 (August 28, 1988), which is used in combination with copper electrodes and consists essentially of a mixture of approximately 1 part 36% aqueous solution 1 hydrochloric acid, -'/8' to 4 parts ethyl alcohol and about 2 /2 grams per 100 ml. of cuprous chloride. V

Instead of employing electrodes and an electrolyte which undergo no change in their chemical constitution by the passage of the current, electrodes and an electrolyte in which such change does occur may be employed, but in this case it is desirable to select the electrolyte connected to the output leads 2|, 22 or the pickup device I0 and to be energized by an A. C. source I. The network shown in Fig. 4 has its output-leads 25, 26 connected to the loudspeaker 30 and is designed to substitute the network 23 in the phonograph assembly shown in Fig. 1.

The electrolyte contained in the pick-up used with the network of Fig. 5 may consist of copper sulphate and the electrodes of copper plates or of mercury nitrate with mercury electrodes, or any other suitable combination of electrolyte and electrodes.

The network shown in Fig. 5 includes a Wheatstone bridge 0, the three arms of which are made up by resistors I4I, I42, and I43, and the fourth arm of which is constituted by the electrolytic resistance of the pick-up inserted between the leads 2! and 22. The bridge is supplied with an A. C. current by means of a source 5 having a frequency f.

It is apparent that when the needle l5 occupies a neutral position the voltage across the output terminals of the bridge I40 is zero. Whenever, the needle I5 deviates from its neutral position, there appears a voltage across the output terminals of the bridge, the frequency of which is f and the amplitude of which is proportional to the amount of the displacement of the needle. Consequently, when the displacement of the needle continuously varies due to the vibratory motion, the unbalance voltage appearing across the output terminals of the bridge I40 is being represented by a modulated carrier, the frequency of the carrier being the same as that of the source I44 and the modulation varying in accordance with the vibration of the needle I5. It is desired to reproduce the vibration of the needle and I am accomplishing this by demodulating the unbalance voltage derived from the Wheatstone bridge, Thus, the instantaneous value of such a demodulated voltage will represent at any instant the magnitude of the displacement of the needle I5 from its neutral position and the polarity of this voltage will indicate at any instance whether or not the 1mpressed displacement has been efiected in the right or in the left direction. In order to accomplish this purpose, I am applying the output terminals of the bridge I40 to a ring modulator contained within the dotted rectangle I60. The ring modulator IE0 is provided with two pairs of input terminals I4'Ia, I4Ib, and I'I5a-, I'I5b, respectively, and one pair of output terminals 25 and 20.

The input terminals I 41a and I4'Ib are connect rier telephone system-s, the BellSystem Technical Journal, vol, XVlll, 1939, pp. 315-337.

The type of the circuit contained in the dotted rectangle I is illustrated in Fig. 20, page 318 of the said article. The ring modulator is essentially a double balanced modulator, By double balanced is meant a modulator in which each input is balanced out from the output, and the output contains therefore substantially only the modulation products.

Consider now the ring modulator circuit contained in the rectangle I00. The circuit shown therein comprises a bridge circuit consisting of four rectiflers I8I, I82, I88, I each of the'said rectifiers constituting a separate arm 01' the bridge circuit and arranged so that the current can flow only in an anticlockwise direction. The upper corner of the bridge I85 and the lower corner of the bridge I88 are respectively connected to the input terminals Illa, Illb and are also connected one to another by means of equal resistances I81 and I88 in series. The other corners of the bridge I88 and I88 are respectively con. nected to the output terminals 25, 28 and are also connected one'to another by a pairot equal resistances I8I, I82 in series. The other input terminals Il5a, Il5b of the ring modulator are respectively connected to the point I88 connecting the resistances I81, I88 and to the point I8l connecting the resistances I8I, I82.

With the circuit as described, current derived from the terminals Illa, Illb may flow either through the rectiflers I82, I83 or through the rectifiers I8l, I8I depending upon its direction, but it can never flow through all the four rectifiers at the same time, since the rectifiers I82, I83 on one hand and the rectifiers I8l, I8I on the other hand are arranged to flow in opposite the terminal "51). Then one part of the current tends to flow from the terminal 5:: to the terminal I83 and through the resistor I 81 to the terminal I85 and then through the rectifier I82 and through the resistor I8I back to the terminal I151). The other part of the current tends to flow from the terminal Il5a to the terminal I83 resistor I 8| is increased as compared to the current flow through the resistor I82. Thus, the volta e drop across the resistor I8I becomes greater and a positive overall voltage is developed across the terminals 25, 28. It can be also readily seen that when the unbalance voltage applied across the terminals Illa, Illb increases in magnitude the corresponding resultant voltage obtained across the output terminals 25, 28 increases in magnitude also.

It can be shown that if the polarity of the first input voltage would reverse with respect to the second input voltage, i. e., if we suppose that the terminal Illa becomes positive as compared to the terminal "521 and the terminal Illa becomes negative as compared to the terminal Illb, then the balance becomes oilset in the opposite direction, because there is a situation where the current flow through the resistor I8I is decreased as compared to the current flow through the resistor I82. Then the voltage drop across the resistor I 8| becomes smaller and the overall voltage developed across the output terminals 25, 28 has a polarity opposite to the case described above.

It can also be shown that in an intermediate situation where the sgnal voltage derived. from the input terminals Il5a, Il5b is displaced by '90 and through the resistor I88 back to the terminal I88 and through the rectifier i8l and through currents flowing through the resistors I8I, I82 are equal and of opposite directions.

It is apparent that under the conditions described in the proceeding paragraph, the polarity of the terminals I85, I86 will be positive with respect to the polarity of the terminals I88, I80. Consequently, positive voltages are applied to I84. Therefore, these rectifiers will lose their ability of rectifying currents, and

' will allow currents to traverse themin both directions. At the same time negative voltages are applied to rectifiers I8I, I 88. Consequently, the rectiflers I8I, I83 will retain their rectifying ability and will block currents attempting to traverse them in the negative direction. Therefore, the rectifiers I82 and I84 are conductive in the resistor I82 back to the terminal Il5b, The

both directions and consequently,.when the unbalance voltage is being developed across the terminals Illa, Illb, we find that a current tends situation where the current flow through the degrees with respect to the voltage derived from the input terminals Illa, Illb then the D. C. volt- 'age output from ring modulator is zero.

Let us designate the voltage applied across the terminals Il5a, Il5b as E sin 21 it. Then the unbalance voltage derived from the Wheatstone bridge and applied across the terminals Illa, I llb can be representedby a carrier of the frequency 1, modulated by the vibration of the needle I5 according to a function A(t) which, represents the variation 01' the instantaneous. displacement of the needle I5 with respect to its neutral position. qonsequently, the unbalance voltage applied to\ the terminals Illa, Illb can be represented by the following expression: A(t) sin 21r it. It can be readily appreciated that under these conditions the voltage derived from the output terminals 25, Not the ring modulator varies with time as the function A(t), i. e., this voltage represents the vibration of the needle. The voltage derived from the ringmodulator is subsequently applied to the loudspeaker 30 in which the vibrations of the needle are being reproduced.

I claim:

v 1. In a phonographic pick-up device, adapted for the translation of mechanical oscillations from the undulating groove of a moving record into corresponding electrical oscillations and including vibration translating means: the combination of a stylus adapted to engage in and to be vibrated by the groove of said record and to infiuence the translating means, the translating means comprising a vessel containing electrically conductive fluid with electrodes immersed in said fluid, and means responsive to the vibrations of said stylus for varying the relative position of said electrodes as a function 01' said vibrations whereby the resistance of said fluid between said electrode varies, an electric network connected to said electrodes and a source of voltage connected to said network whereby the variation of said resistance between said electrodes produces electrical oscillations in the output of said network, said oscillations representing the undulations in the groove of said moving record.

2. In a phonogr'aphicpick-up device, adapted for the translation of mechanical oscillations Irom the undulating groove of a moving record into corresponding electrical oscillations andineluding vibration translating means: the combination of a stylus adapted to engage in and to be vibrated by the groove of said record and to influence the translating means, the translating means comprising a vessel containing electrically conductive liquid with metallic electrodes immersed in said liquid, said liquid comprising in solution a substance having in its chemical coinposition the same metal as that of which ,one of said electrodes consists, and means responsive ,to the vibrations of said stylus for varying the relative position of said electrodes as a function of said vibrations whereby the resistance of said liquid between said electrodes varies, an electric network connected to said electrodes and a source of voltage connected to said network whereby the variation of said resistance between said electrodes produces electrical oscillations in the output of said network, said oscillations representing the undulations in the groove of said 'moving record 3. In a phoncgraphic pick-up device, adapted for the translation of mechanical oscillations from the undulating groove of a movingrecord into corresponding electrical oscillations and in-- cluding vibration translating means: the combination of a stylus adapted to engage in and to be vibrated by the'groove of said record and to influence the translating means, the translating means comprising a. vessel containing a conductive fiuid, electrodes immersed in said fluid in a determined spaced relationship one from the other, whereby the resistance between said electrodes has a determined value corresponding to said relationship, electric circuit elements connected to said electrodes to form a bridge network, a supply of current connected to said network for energizing said network, the values of said circuit elements being such as to balance said network for said determined spaced relationship between said electrodes and thereby produce no voltage in the outputof said network, means responsive to the vibrations of said stylus for varying the relative position of said electrodes as a function of said movements whereby the resist--

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