US2247651A - Phonograph - Google Patents

Description

PHONOGRAPH Filed May 31, 1939 2 Sheets-Sheet 2 Patented July 1, 1941 PHONOGRAPH Benjamin R. Carson,

Radio Corporation of America,

Delaware Camden, N. J., assignor to `a corporation of Application May 31, 1939, Serial No. 276,685

6 Claims.

.This invention relates to phonographs, and more particularly to the driving means for the turntable thereof, the present invention being particularly useful in automatic phonographs of the type wherein a series of records are automatically played in succession upon the turntable.

Itis well known that it is hardly possible to lmanufacture driving motors which are so mechanically and electrically perfect that they do not constitute a source of mechanical vibrations. In conventional phonographs, this has been a great source of annoyance for the reasonA that these vibrations are transferred to the turntable and affect the quality of reproduction.

The primary object of my present invention is to provide an improved phonograph turntable drive which may be used in connection with phonograph motors generally available butl without the objectionable result heretofore noted.

More particularly, it is' an object of my present invention to provide an improved coupling between the turntable and the driving motor which will practically eliminate the transference of motor hum and vibrations to the turntable.

Another object of my present invention is to provide an improved phonograph turntable drive mechanism as aforesaid by means of which speed' variations, commonly known as wows, will be greatly minimized.

A further object of my present invention is to provide an improved turntable drive as previously set forth which will transfer power from the motor to the turntable with great efficiency.

Still a further object of my present inventionis to provide an improved phonograph turntable mounting wherein the load of the motor will be largely removed from the turntable supporting board. l 'aI It is also another object of my present invention to provide a phonograph turntable drive and mounting which is simple in construction and which readily lends itself to economical quantity manufacture.

According to one form of my present lnvention, I mount the motor upon a motor plate which is in turn mounted upon the motor board, the motor including a driving shaft which extends upwardly through the motor board a shortl distance. Resiliently mounted on top of the motor board is a second plate which rotatably carries the turntable spindle, a plurality of aligning posts serving tovalign the two plates in such a manner that the turntable spindle and the motor shaft will `be in substantial alignment. Preferably, the aligning .posts are mountedin rubber grommets or washers on the aforesaid second plate so as to prevent rumble and other vibrations originating in the motor from being transferred to the second plate and the turntable spindle through the aligning posts.

- along the line V-V of Fig. 1.

The motor driving shaft and the .turntable spindle are not only substantially axially aligned,

but are' also in axially spaced relation, and eachcarries a diametrically extending arm, the two arms' being superposed over and spaced from each other.- On the ends of the arm carried by the motor. shaft, `there are mounted Ysoft rubber `10 grommets in which are frictionally received downwardly extending pins on the ends of the arm carried by the turntable spindle. Thus, a

resilient coupling is provided between the driving shaft and the spindle which absorbs vibra.- tions originating inthe motorand prevents their transference to the spindle and the turntable.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, as well as additional objects and advantages thereof, will best be understood from the following description of one embodimentqthereoi, when read in connection with the accompanying drawings, in which- Figure 1 is a plan view of a phonograph embodying my invention,

Figure 2 is a sectional view taken along the line II-II of Fig. 1,

Figure is a detail sectional view taken along line III-III of Eig. 2, l l

Figure 4 is a sectional view taken along the line IV-IV of Fig. 1, and

Figure 5 is an enlarged detailed section taken Referring more particularly to the drawings', lwherein similar reference Icharacters designate corresponding parts throughout, I have shown, in Figs. 1 and 2, a motor board I having a pair of blocks 3`secured thereto on which a motor plate 5 is mounted by means of screws 1, the motor plate 5 carrying a motor 9 provided with an upwardly extending driving spindle I I. Preferably, the plate 5 is provided with elongated holes 5a so that the plate 5 may be adjusted' transversely of the motor board for a purpose presently to be set forth. Threaded into the motor board I, as more clearly shown in Fig. 5.

are a plurality of mounting screws I3 surrounded by coil springs I5 which are received in cup members I'I resting on the motor board I.. Asecond vplate I9 has mounted thereon a plurality of washers 2| ot soft rubber in which the mounting screws I3 are received and which vibration insulate the plate I9 from the motor board I, the plate- I9-resting upon the coil springs I5. l

Staked vor otherwise suitably secured to the' plate I9 is a bushing 23 in which the hollow hub 25 of a turntable 21 is rotatably received, a-'turntable spindle 29 being mounted in the hub 25

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