US1909995A - Reproducing system - Google Patents

Description

May 23, 1933. YElDER 7 1,909,995

REPRODUC ING SYSTEM Filed April 23. 1930 Inuen Ur Harry 5.5[515512 Patented May 23, 1933 UNITED STATES HARRY A. YEIDER, or GRAND RAPIDS, MICHIGAN,

INSTRUMENT WARE PAT-m"omen REPRODUCING- SYSTEM Application filed April 23,

transmitting the same to a remote point.

. More specifically, the invention'relates to an improved circuit arrangement for caus-' ing sound waves to be translated into electrical waves by means of a variable condenser of novel construction. In the em-, bodiment of my invention illustrated in the attached drawing I have applied my invention to a phonograph reproducer or pickup? device. A In this embodiment the vanable condenser of my invention is operated by the needle of the phonograph and translates the mechanical vibrations or convolutions of the record groove into corresponding electrical waves. V

' Among the features of my invention are the provision of an improved translat ng and amplifying system for reproduclng sound; to provide a novel reproducing sys tem employing a variable condenser, to pro-. vide a condenser pickup for phonographs which gives truer reproduction and greater amplification due to the design. of the C11- cuit and to the fact that the moving parts are simpler, lighter and have exceptionally free movement.

The embodiment by means of which I have chosen to illustrate my invention is shown-in the accompanying sheet of drawing in which 7 Fig. 1 is a top view of .thetone arm of. a phonograph with certain parts thereof shown in section.

Fig. 2 is a view of the device of Fig. 1 taken from the bottom of Fig. 1 and also having most of its parts shown in section.

Fig. 3 is an end view taken from the rightof Fig. 2 also having certain parts shown in section. V

Fig. 4. is a view taken from. the bottom of Fig. 3 to more clearly show the arrangement of the parts. c

Fig. 5 is a circuit diagram showingthe 4 electrical connections and circuit operation of the improved translating and amplifying system. Y It has become common practice since the the condenser.

1930. Serial No. 446,490." I

combination of radio receiving sets and phonographs to use: the so-called magnetic pickup fortranslating the mechanical vibrations of the needle into electrical waves for transmission to the I'loud speaker. Although such devices have been-fairly satisfactory I have found thatthe present design of a variable condenser. pickup gives greater volume, truer tone, and less distor tion due to the lighter. moving parts.

Referring to the accompanying drawing,

figs. 1 and 2, I have shown at 1 the usual mounting for a Connected thereto .and'rigid therewith is a thin metal tube 2 with its ends closed with parts 3 and 4. each of which has a rubber bushing in a socket on its inner face. The stylus bar 5'is mounted at each end inthese bushings .6 and 7. The stylus holder 8 is secured to bar 5.0n an angle as shown preferably by solder or a rigid joint of any type and extends down through? a large opening in the lower side of tube 2 as shown. A spring and plunger needleiejec tor is mounted inside the stylus"h0lder.- the opposite end of the stylus bar 5 is another hole threaded to receive a'stud 9 which also projects out through a large opening in tube 2 down inside the dome mounting 1. The lower end of stud; 9 is reduced to a small diameter and mounted thereon by aset screw 10 is acopper plate 11 which has an enlarged upper portion containing a hole which fits over the reduced end of stud 9, and which-isadjustably' held by set screw 10. Around the tube 2 and inside the dome mounting 1 is a 'U-shaped metallic bracket 12 inside of which isa thin metal retaining member 13,'also U-shaped and fitting tightly around-'thetube 2. Both brackets 12 and 13 are secured together atthe top and also secured to the' tube 2'by phonograph tone arm.

7 ASSIGNOR ro AU'roMArIoMUs cAI. V COMPANY, or GRAND RAPIDS, MICHIGAN, A CORPORATION or nEL soldering or other means. The bracket 13 at itslower ends has extending arms ltand 15 which are bent outward and fit snugly around bracket 12 to hold it rigid, lugs 14 and 15 are also soldered or secured to brack-v et'.12. .Bracket l4; has an extending tip 14 which may be used. as one terminal of I In one of the, lower ends parts of bracket 12 (Figs. 3 and 4) is an insulating bushing 16 through which extends a stud 17 which is welded to and supports a copper plate .18 adjacent the plate 11. Between the plates 11 and 18 is a dielectric of paper, mica, or other insulating material shown at 19 and the plate 18 is held clamped close to the dielectric by nuts 20 and 21 which also. hold a, copper terminal 22 in contact WithJstud 17. and therethrough to plate 18to provide a second terminal for the condenser. other arm of bracket 12 is a stud '23'threaded into a hole in the bracket and having wation and are shown here only as an adjunct.

to my present invention.

As is usual in such devices, the tone arm is mounted as indicated in Fig. 2 by a universal joint to a platform such as'26, only of which are shown. Thus it will be seen that when the stylus 8 is placed on a record the sidewisemovement thereof when following the curves or convolutions of a.

groovein a record will be communicated 5 through the stylus bar 5 to the study 9 and. thence to. the copper plate 11. The corre sponding sidewise vibrations of plate 11, will causevariatious of the capacity of the condenser formed by plates 11 and 18 and the dielectric 19 by varying the. distance between the plates.

Referring now to shown in Fig. 5, I will explain the connection and function of the variable condenser shown in Figs. 1 1. At V I have'shown a welllmown, type of 3-element vacuum tube having filament, grid, and plate. 'The tube may be the direct or alternating current type of tube as desired and will of-course 3 have the usual connections to a battery for energizing. the filament, a connection to battery through resistance 27 for biasing the, grid, ,andthe usual B battery connections to the plate, theoutput to loudspeaker or the like may-be taken through the primary of a transformer such as shown at 28 if desired. As any type of tube may be used, ;I have not shown the A, .B, and 0 batteries. but only indicated the same by lettersr 1 Across the input'of thetubeI connect .a source of high potential direct current ofa value which maybe approximately 500 volts as shown; 1 The positive sidejof the direct current source is connected through'resist- In the lower end of ,the.

the circuit diagram.

ances 29 and 30 and through a series con denser 31 of fairly high capacity to the grid of tube V. The negative side of the 500 V source is connected to the midpoint of a resistance 32 bridged across the filament of the tube. A condenser 33 is bridged from the negative side of the high potential source to the midpoint between resistances 29 and 30 and these two resistances and 30 and condenser: 33 actv as a smoother for thehigh' potential direct current source tov prevent variations .or undulations in the voltage thereof from reaching the tube. At a point between the resistance 30 and condenser 31 the variable condenser 34, which comprises plates 11 and 18, has one of -it'splates connected and the other plate isconnected tothe negative'side. of the, highpotential battery.

It is well understood that variation s in the impressed'electromotiveforce on the grid of the vacuum tube cause variations in the flow. of electronsbetween filament and plate and produce amplified changes in the current flowing in theoutput circuit of the tube. It will be, seen, therefore, that as the needle or stylus 8 causes variations in the capacityv of condenser 34 by compressing plates. 11 and18,that thesaid variations in capacity ofcondenser 84. will cause Variations in the charge carried by the condenser 31 and therefore cause a correspondingly varying voltage to be set .up in the grid circuit of the tubeV. As long as condenser 34 is not varied the tube is inactive and the condensers 34. and 31-stan'd charged. The use of the high voltage and theconnection of the variable. condenser84 as shown causes sharp and rapid changes-in the grid potential and correspondingly strong and rapid'current changes in the plate circuit resulting from changes in capacity of'condenser 34..

The action of the circuit will be understoodby those skilled in the art, and it will be seen that as the capacity of condenser 3 1 is increased by plates 11 and 18 coming close together, it will cause a lowering of the potential on grid of tube V; Alsoas plates 11 and 18 are drawn apart and the capacity is decreased, a current will flow through condenser 31'and in the opposite direction over and above traced circuit, to cause consequent increases of the; voltage onthe grid.

'It Wlll be seen, therefore, that I have provided a very eflicient :and simple type of pickup and that very slight movement. of. the plate ll of condenser 34 produces corresponding amplified fluctuations in the plate circuit of the amplifier. As previously suggested, although the invention is illustrated as a phonograph pickup,it should be understood that the'plate 11 of condenser 34 may, if desired, be vibrated directly by adiaphragm or in any other desired inanher to reproduce sound, and also that various changes may be made in the detailed arrangement illustrated without departing from the spirit of the invention.

Having fully described and ascertained the features and aspects of my invention, what I consider to be new and desire to have protected by Letters Patent will be pointed out'in the appended claims.

What is claimed is:

1. In a device of the class described, a pickup supporting arm having a rod'yieldingly supported therein, a stylus mounted on one end of said rod, a plate mounted on the opposite end of said rod, another plate adjacent said first plate and a dielectric between the plates forming a condenser,

the vibrations of the stylus causing corresponding vibrations of the first plate through the medium of said rod and consequent variations in the capacity of the condenser.

2. In a device of the class described, a variable condenser comprising a stationary plate and a movable plate, a dielectric separating said plates, a rod supporting said movable plate on one end thereof, a stylus mounted on the opposite end of said rod and extending sidewise therefrom and ar-' ranged to communicate its vibrations to the condenser by rotating said rod on its own axis to vary the capacity of said condenser, means for adjusting the normal capacity of the condenser by spacing the movable plate from the stationary plate, and means responsive to the variations in capacity of the condenser for producing corresponding electrical variations in a circuit. 7

3. In a device of the class described, a pickup supporting arm pivotally mo-rnted at one end, the other end being rotatable abouirsaid pivoted end, a condenser mounted on the pivoted end of said arm, a stylus mounted on the movable end of said arm and having means for producing variations in the capacity of said condenser, and means responsive to the capacity variations of the condenser to produce corresponding electrical variations in a circuit.

In witness whereof, I hereunto subscribe my name this 17th day of April, A. D. 1930.

HARRY A. YEIDER.

Images