US2472770A - Resistance apparatus for converting mechanical movement into electrical pulses - Google Patents

Description

June 7, 1949. E L JR 2,472,770

RESISTANCE APPARATUS FOR CONVERTING MECHANICAL MOVEMENT INTO ELECTRICAL PULSES Filed NOV. 20, 1945 INVENTOR L eoLHelterline Jr. M

- ATTO R N EY sound as recorded. h I

which varies" Patented June 7, 7949 "cimm'sns AP ARATUSFOR'CONVEIWMG MovEMEN'rlmmo-EmomL El'ectrleProducts lnc sitlemjMals corporation lbtsMassaclmsetts e acilfistsmei em l range of tilt! o-ifiquhcies. s

'fiirthei obiectibf :h-ifitefitibm is" 5 m .Ii'i'o'i i'de a. sound record niodiiliztbr' 'ihavinrincreased .power outfiut. I I

"*A fu'rther dbieot bf' th ihi'eiitiori'isto provide 'a sound record "Heidi-device having greatly reduced un eusnee ene;:nawre of which is substsnda-ny an iihin'i "resistance. 7

*Other' objects 'h'nd ieitizies willfm'bre "fully 'appear from the following descri'fitfon andwill be particularly pointed out in the creams.

The biesent"invention conifiiises essentielly an electric circuit he g'*therein 'a source "of energy, i lo'ad' impedance n snsenigy maauiatmg-aeview-consisting 619', ontiot ribai'rierimpedance fifiifiiii'ctio pi'essiire aiid means for 'n ichan'fally vsrymmh prssure on the 1 idifi ihibedaiice.

s'uitapifimiiedgnee llliisttetd' rierin I theg-type sir'ggested is wnerelm metallic cimtasting "'eng ages en electric-any conductive crystal.

be iit'ilizedto seventeen-laureate: oft-suitable type for 'vis-ual" ofiaiidioobsertttion.

described and-illustrated in the drawings'iin non-serum airecotd -rehdi cam-rem iti'into a. mo'du- 'HtedQbOtefiiiiaI;

siiitnemsamior ruga susa diag ra' minatic fldewiliustriting"the appli'c'ation o'f the ihVeiition =t6therD1ddizb6ion ofsound.

The invention has various applications-where it *is 'desired to provide ai sensitive aridreadily perceived response to slig'ht. nieehanicaHmovementsor pres-sures sucnasdn mee'hanicai'--'strain gauges oiin delicateend flizcflratEfi-inifisidnal gauging-apparatus.

A partieul-ar- (re licationdescribed and illustrated herein "in' which -thewrineipiefinvoivedi is al pl ied' to ai'sour'id 'tecolid pidku device.

-The particular embod ment Hown isincorberated I in -a convemimiaiesound -i-ecord epparatus such as used for entertain'm nfipurposes and consisting of a eabmet =i=-iv hirr' whichris received a means :for driviii'th tilmtaibl 2 'and a sound rep'roducingfi apparetus"the soundfrom which emergesat the--g rill workiopenipg '3. A tone arm 4- is suspended iii-the usual -'m'anner' and adapted to carry" an enei 'gy" modulates-meme er' S embodyingthe' ii'ive'nt'ion "File-member 5 is supportedin-the 'fr'ee' eiid o the-tone airmfin'positionto engage a 'fsouii'dere'cbrd 6-"' upon the turntabled.

The energy modulate? -5= desirab1y is enclosed in acas'ing T or suitable materials-auditorconveliience in= asseiiibling is oomp'o'sjd of two separable'sec-tion's' held to'geth'ei by screws 8. Within the casing iS-re'ceiVed a i'otatabledrivingshaft 9 supported atits' 'enHsdnthe easing. '-.The' shaft 9 receives impulses from th re'cord 5 which=has a latemlly out" soundq g-roove 1 11 ther'ein. II -he impulses are transmitte'd -toi the FShiffiby, the needle H secured iifth-shait. 'ThenG'edIe-may be replaceable or ma'y be -fdf the=-permanent -type having a -j'eweied tip -and f fiirediy secured" in the shaft.

i The impulses at the 'shaft are" iii-the =form-"-of short rotativ oscillations which are in "turn transmitted to an' -a'rm 12 rigidly secured -'to and extending out i-1 0m the.= 'sh-aft atsub'stantiaIIy" from the needle -At-the*-io1iterend" of the arm I z is secured a wire 3 0? condu'ctive'metal cominto a form to provide resilience and has a straight portion 'atrvi't's-kbdttome'rid' which resib iently engages the siirfece OP e piece *of electri- Cally 1 conductive' ci'y-s'tm '14." "-Ehe -'-elen'ient'- may be silicon -germanium or other material which will constitute a "cont'eicti or liarrier type impedance wli-ich-avaries as'adunctiomof pressure, andis prov iiied ?with? electrical r'connectionin the for-nibfa mefialil fcehoidei' f5 td-Tivhi'ch aflead wire 16 is secured. Desirably tl'i hfilfler lifls 3 adjustable axially of the wire l3 within the easing l. Any suitable means may be used to hold the element M in adjusted position such as the set screw II.

By way of example the member l4 may be a crystal the face of which is arranged substantially upon a'plane passing through the axis of the shaft 9 and the straight portion of the wire [3 is perpendicular to the crystal face. This 1 arrangement of crystal and wire provides true straight line action in operation.

The casing 1 is provided with a chamber [8 to provide space for the elements of the device and an opening [9 is provided in, the casing Within which the needle moves. the shaft 9 are received in rubber bushings 20 which are in turn received in closely fitting apertures in the casing. By thus supporting the shaft undesirable vibrations are eliminated due to the snubbing action of the rubber. To further control unwanted vibration-s a pad of rubber 20m may be inserted between the upper surface of the arm l2 and the wall of the chamber I8. To complete the electrical circuit through the device a flexible lead wire 2! is connected to the wire l3. The connection to thewire is desirably made through the shaft 9 and arm is by soldering the wire to one end of the shaft. The lead wires l6 and 2| are lead through the tone arm and connected in the electrical circuit of the apparatus. The energy modulator may be supported in the tone arm in any desired manner such as by means of screws 22 passing through the casing l and having threaded engagement with the top wall of the tone arm.

Fig. illustrates one manner in which the modulator member may be employed in a sound reproducin apparatus. The modulator is connected in series in a circuit 2 3 containing a load resistor 25 and a direct current source such as the battery 26. An output connection is made from one end of the resistor 25 to a blocking condenser 21 of suitable capacity which in turn is connected to one or more stages of audio amplification. It may be found desirable to change the relative position in their circuit and the values of the resistor 25, the battery 25 and the condenser 21 to obtain a desired circuit characteristic. One audio stage is shown and any suitable means may be employed to couple the modulator thereto. As shown the blocking condenser 2i is connected to a coupling impedance 28. The varying potential at the impedance is conducted to the control grid of an amplifier-tube 29 by means of a connection 30. The output of the tube is conducted to a suitable sound device such as the loud speaker 3i through a suitable coupling transformer. The tube and loud speaker are supplied with operating power in any desired manner not shown.

An A. C. source of current may be used in place of the battery 26. Such a source may have a frequency of from approximately 10,000 cycles to 100 megacycles. In this case the material for the member it must be capable of functioning as a rectifier as well as a modulator.

The impedances and condenser may be of any suitable value. The impedance may be fixed or variable and may be of the order of 1000 ohms to one or more megohms. The D. C. source may supply any voltage, desirably 100 volts or less. The impedance 23 may be fixed or variable and may be of the order-of 3% megohm and the condenser 21 may have a capacity of substantially -.0 icr fa ed- Desirably the ends of For best performance the position of the crystal [4 should be adjusted to provide a firm pressure of the wire I3 upon the crystal. In operation the resiliency of the rubber bushings 20 and the pad 204:: permits the record 6 to cause the arm l2 to move up and down which varies the pressure of the wire it upon the rystal which in turn varies its resistance and. thereby produces a potential across the impedance 25 which varies in accordance with the original sound as recorded on the record. The varying potential is amplified by the tube 2'! and converted into sound by the loud speaker 29.

The operation of the apparatus is highly efficient and produces highly accurate reproduction of a desired band of audio frequencies. A contributing factor inits efficient operation is the relatively low impedance of the crystal and wire combination which is of the order of 10,000 ohms. This impedance is very low compared to other devices of a similar nature. For example, a piezoelectric modulator device may have an impedance as high as 10 megohms at audio frequency. The sound pick up device of the present invention therefore makes available as much as one hundred or more times the power developed by other types of pick up devices.

Another advantageof the invention is the fact that the modulatormember presents an impedance which consists practically entirely of ohmic resistance. The invention thereby eliminates stray capacity and inductive factors. Thus it becomes unnecessary .to introduce compensating elements in the circuit. The invention therefore is capable of very accurate operation and moreover permits greatflexibility in the design of circuits in which it may be used.

It has been found that very efficient crystals for use in the apparatus are a silicon crystal having aluminum dispersed therein or a germanium crystal having tin dispersed therein as disclosed in the copending application of E. T. Casellini, Serial No. d92,163, filed June 23, 1943, for Electrical. rectifiers. I

What I claim is: v i

. 1. In an apparatus for producing electrical impulses from a sound record having a groove therein, a modulator member comprising a casing an operating shaft supported in the casing for slight rotative oscillating movement, a sound record having a sound groove therein, a pointed needle engaging the sound groove and acting to move the operating shaft in accordance with the sound record in said groove, anarm secured to and extending outward from the shaft, a resilient wire secured to the outer end of said arm. a semi-conducting member having a face thereof disposed in engagement with said wire said semi-conducting member having the characteristic of varying the impedance of its contact with said wire in accordance with varying pressure applied thereto,

and electrical connections from said wire and semi-conducting member for connection in a circuit. n a r 2. In an apparatus for producin electrical im-. pulses from a sound record having a groove therein, a modulator membercomprising a casing, operating shaft supported in the casing for slight rotative oscillating movement, a sound record having a sound groove therein, a rigid pointed needle engaging the sound groove and acting to move the operating shaft in accordance with the sound record in the groove, an arm secured to the shaft, a resilient wire secured to. the outer end of the arm,- an electrically conductive crystal mounted in the casing having its face disposed in engagement with and substantially perpendicular to said wire and electrical connections from said wire and crystal for connection in a circuit.

3. An apparatus defined according to claim 2 in which the crystal is of silicon having aluminum dispersed therein.

4. An apparatus defined according to claim 2 in which the crystal is of germanium having tin dispersed therein.

5. In an apparatus for producing electrical impulses from a sound record having a groove therein, a modulator member comprising a casing, an operating shaft supported in the casing for slight rotative oscillating movement, a pointed needle engaging the groove in said record and acting to move the operating shaft in accordance with the groove in said sound record, a semiconductor member having the characteristics of varying its impedance in accordance with the pressure of a contact on its surface, a contact to said surface, said contact being one. end of a resilient wire, means connecting another part of said resilient wire to said operating shaft to vary the pressure exerted on said resilient wire in accordance with the movementfof'said shaft, and electrical connections from said wire and said semi-conducting member forccnnec'tion in a circuit.

LEO L. HELTERLINE, Jn.

REFERENCES CITED The following references areof record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Proc. of the Natl. Acad. of Sciences, vol. II, 1-925, pp. 743 to 748.

Images