US1298019A - Turn-table for talking-machines. - Google Patents

Description

J. A. DAVLS. TURN TABLE FOR TALKING MACHINES.

APPLICATION FILED AUG-7A l9l6.

Patented Mar." 25,1919.

INVEN FEH th 'objectionable noise. The vibrations of machin FFEQE JOHli DAVIS. 015 BOSTON, MASSACHUSETTS.

TURN-TABLE FOR TALKING-MACHINES.

,citizen of the l nited States, residing at Boston, county ofv Sutfol l State of i\la'ssachusetts, have invented a certain new and useful Improvement .111, 'lurn-lables for Talkiing-liiachmes of which the following is a specification, reference being had there in to the accompanying drawings.

My nventionhas for its ob ect a. new and improved turn .'.table for talking machines' and particularly for electrically operated although' it maybe used with equal c soon those which are mechanically opei ted "f I chinesa're operated by electric motors the current forwfhich i taken from the ordinary lighting circuit. This method of operation has certain obvious advantages but serious,di'tliculties have arisen, particularly as. the" result of theluse of metallic turn tables Ion ,wl ich,;thefrecords are placed. The I1()l$e. of the dr v ng mechanism is trans ini ttedgthrough the; spindle to the metallic tur tableffwliich being resonant tends to magnify -it and' distribute it'thus increasing the ilresona-ht ti'irn t'able are to some extent transmitted to the record and thus through the needle to the sound box interfering with the reproduction of the record and the purity-of the tone therefromand introducing extraneous noises into the sound reproduction. j

Furthermore as electric-ally operated talking machines are arranged for connection with the ordinary lamp circuit which is commonly 110 or 220 volts and as there is always danger of a short circuit in the instrument, there is danger of an electric shock to any one touching a metallic turn tablewhich is in electrical connection through the spindle witli the other metallic parts of the instrument. There'i also equal danger of fire from a short-circuit.

Accordingly my invention has for its.object a new and improved turn table which overcomes completely the various objections previously inentionedv The turn table embodying my invention is molded from a suitable insulating coinpound such for instance a one in which pulverized asbestos, mica, gum shellac and asphaltum are ingredients. This material is plastic when heated and is capable of beingmolded Specification of Letters Patent.

'prese'nrttime many talking ma under heavy pressure and on cooling is rigid, strong, hard and an insulator capable of withstamlinga relatively high voltage.

The turn table embodying my invention also contains other important features which contribute to its usefulness and the ease with which it may be manufactured.

The invention will be .fully understood from the foll c'iwi'ng description when taken in connection with the accompanying drawings and the novel features thereof will be pointed out and clearly defined in the claim at the close of this specification.

In the drawings, l hg'urt l is a top plan view of a turn table embodying my inven tion. i

Fig. 2 is a side elevation of the same.

Fig; 3 is a section on line 3 3 of Fig. 1.

Referring to the drawings, there is shown at A the disk portion of the turn table and at B'tlie .l1i'ib. is stiffened by ribs (1 which connect with the hub and increase the rigidity of the finished structure so that it cannot be sprung if dropped or leaned upon when in place upon the spindle of'the machine with which it is used. These parts are molded integral from the insulating material chosen as fol-instance the plastic composition mentioned above.

Theupper side of theturntable is covered with felt D on which the record rests This felt serves to make a frictie all contact between the turn table and the record. In my preferred fol-n1, I provide an annular piece or ring of felt avhich extends from a point a short distance inside of the circumference of the turn table to a point from one to three inches from the center of the disk A. I also form an annular depression E in the surface of the turn table underneath the outer eclge of the disk of felt and another annular depression F underneath the inner edge of the felt thereby causing the edges of felt to lie slightly below the plane of the surface of the turn table. -The main portion of the felt is above the level of the turn table. It is to be noted by reference to Fig. 3 that the outer edge of the depression E forms shoulder G, while the approach to the shoulder G has a gradual slope. Similarly the inner edge of the depression F forms a shoulder H, while the approach to said shoulder has a gradual slope. The edges, therefore, of the felt disk D are entirely below the general surface of the table, the edges of the felt both on the inner periphery The underside of the disk application filed August 7, 1916. Serial No. 113,504.

and the outer Iplriphery abutting up against the shoulders and respectively, leaving no exposed portion whatever of the edge. Thus the upper surface of the felt has a sort of crowned eflectand thefelt isenabled to support the record free from any contact whatever with the composition body of the table, although there are no upwardly projecting shoulders or nubs. This construction enables the felt to be applied to the turn table more smoothly andrapidly and it isless likely to become unsecured around its edges and ,to work up as has heretofore been the case; It-also makes it easier to put the record in place or to remove it, as the edge of lathe record is not in contact with the turn table.

Since theturn table material, the current by whiehthe electric motor is operated cannot be transmitted 7 through the turn table to the'opei'ator or to any article which may be in contact with the turn table'thus eliminating the danger.

of fire and increasing the safety of the user of the machine! Since the insulating material of which the turn table is constructed is nonresonant, sounds generated in the instrir nent are not transmitted through the spindle and increased and distributed by the turn table. The sound reproduction is not interfered with by vibration of the turn table transmitted to the record and thence through the needle to the sound box. liurthermore,

' nular piece of of the table disk covering the'space between having in the upper surface two annular depressions which are concentric with each other and with the periphery of the disk,

one of said depressions being located at some distance inside of the margin of the disk, the

other of said depressions being located at a considerable distance nearer the center of a e the disk, the outer depression having an 1s made of insulating abrupt shoulder at its outer periphery, the bottom of the depression having a gradual slope from its inner to its outer edge, the inner depression having an abrupt shoulder at its inner edge, the bottom of said depression-having a gradual .slope from its outer periphery'to its inner periphery, and an anfelt secured to the surface the shoulders of said two depressions, the

. talking machines, the -body portion of which consists of a disk inner and outenedg'es of said felt lying within said depressions so that the edgeslof the felt do not project above the shoulders formed by the depressions in the table disk.

' In testimony whereof I aflix my signature.

' JOHN A. DAVIS;

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