US2244121A - Compensating turntable drive - Google Patents

Description

June 3, 1941. E V, sCHNElDER 2,244,121

COMPENSAT ING TURNTABLE DRIVE Filed Feb. 17, 1941 Patented `une v3, 194i COMPENSATING TURNTABLE DRIVE Emmor V. Schneider, Alliance, Ohio, assignor to The Alliance Manufacturing Company, Alllance, Ohio, a corporation of Ohio Application February 17, 1941, Serial No. 379,227

(Cl. 'I4- 206) 4 Claims.

` duction motors for economic reasons,

Such phonographs however, are not entirely satisfactory, due largely to the fact that these inexpensive motors do not have sufficient power to drive the turntable at a uniform speed from [the start to the end of a record, especially in recording, and also because they will not drive the turntable as rapidly when recording as when reproducing a record.

It has been found that in recording upon this type of phonograph there is a differential of approximately eighteen inch ounces to six inch ounces between the start and the end of a record, resulting in noticeable variations .in both the pitch and the tempo of recordings made upo such phonographs.

It has also, been founcl that there is a dierence of approximately four revolutions per minute between the recording and the reproducing of a record upon such phonographs.

Another objection to this type of phonograph is that the pulsations r vibrations of the motor Vare reproduced to a greater or less degree in the record.

The present invention has for lts objects the provision of a compensating turntable drive for phonographs` which will overcome the above mentioned objections and produce a uniform speed in recording and reproducing of records, as well as minimize the reproduction in the record of the pulsations or vibrations of the motor.

Another object of the invention is the provision of a turntable drive in which the axis of the motor is substantially parallel to the plane of the turntable. and in which a countershaft is provided substantially parallel to the motor shaft, a friction wheel upon said shaft engaging a friction pulley upon the motor shaft, a second friction wheel being slidably mounted upon said shaft and frictionally engaging the turntable, means being provided for moving said second friction Wheel toward and from the center of the turntable -to compensate for variations in the drag or torque upon the turntable between the start and end of a recording," or between the recording and reproducing of a record.

Still another object of the invention is the provision of a turntable drive of this character in which the two friction wheels are connected together byrmeans of a torsion spring through which the drive is effected, so that the pulsations or vibrations of the motor will not be reproduced in the recording or playing of a record.

A further object of the invention is to provide a turntable drive of the type referred to in which the slidable friction wheel is moved longitudinally upon the shaft by means of a screw thread or helical rib.

The above objects, together with others which will be apparent from `the drawing and following description, may be attained in various ways by which a slidably mounted friction vwheel is moved radially relative to the turntable to compensate for drag or torque upon the turntable, and for the purpose of illustration a preferred embodiment of the invention is shown in the accompanying drawing, 'in which- Figure 1 is a fragmentary top plan view of the improved compensating turntable drive;

Fig. 2, a vertical sectional view taken as on the line 2-2, Figure l; and

Fig. 3, an enlarged sectional view through the two friction wheels andassociated parts;

Similar numerals `refer to similar parts throughout the several views.

In the form of the invention shown, a portion of the usual platform of a phonograph cabinet is shown at I0 and the turntable il is rotatably mounted upon the spindle I2 carried by said platform. v

The turntable may be provided with the usual depending peripheral flange I3 although the same is not necessary for the particular friction drive used ln this invention. l

A motor mounting plate I4 may be supported upon the platform I0 as by one or more rubber grommets I5 secured to the platform as by the screw I6 and washer Il, a spacer sleeve It or the equivalent being preferably located around the s'crew and interposed between the platform and the washer ll.

Depending arms I9 may be formed upon or attached to the motor mounting plate and located through the openings 20 and2l in the platform lll.

The motor, indicated generally at 22, is suspended upon the arms I9 to which it may be connected as by the screws 23 and the motor is A bearing 26 is swedged or otherwise connected to one arm I9 of the motor mounting plate to form a bearing for the shaft 21 which is Ilout-- naled in :aid bearing and held against accidental removal as by the flange 28 which may be in the form of a washer located around the reduced end portion 29 of the shaft and retained thereon as by the riveted head 30 formed upon the adjacent end of the shaft.

A friction wheel 3| is fixed upon the shaft 21 adjacent to the bearing 26 as by the pin 32 iocated through the hub 33 of the friction Wheel and through a suitable opening 34 in the shaft.

A tire 35 of rubber or the like is mounted upon the friction wheel 3l and frictionally engages the pulley 25 upon the motor shaft so that the friction wheel 3| and shaft 21 may be rotated by the motor.

A second friction wheel 36 is mounted for longitudinal movement upon the shaft 21 and is provided with a friction tire 31 frictionally engaging the underside of the turntable Il.

This friction wheel may be threaded upon the shaft 21 in any well known manner and as shown the hub 38 of the friction wheel is provided with a spiral rib 39 engaging a similar groove 4U in the shaft 21.-

Outward movement of the friction wheel 36 beyond the adjacent end of the shaft 21 maybe prevented as by the washer 4| located in a peripheral groove 42 formed in this end portion of the shaft.

A torsion spring 43'is located around the shaft 21, one end thereof being connected to the hub 38 of the friction wheel 36 as indicated at 44 while the other end of the spring is connected to the hub 33 of the friction wheel 3|, and to the shaft 21 as indicated at 45.

A skirt 46 may be formed upon the hub of the Wheel 36 to surround the spring 43.

In the normal position of the parts, as shown in Figs. 2 and 3, the spring 43 holds the friction wheel 36 at the outer end of the shaft 21 so that the tire of said friction wheel contacts with the The device thus compensates for changes in drag or torque upon the turntable, providing for a smooth uniform rotation of the turntable throughout the entire recording or playing of a record.

It will also be seen that since the drive is through the torsion spring 43 pulsations or vibrations of the motor will be absorbed by the spring producing a smooth continuous rotation of the turntable.

I claim:

1. A transmission including a driving means, a driven disk, a shaft operatively connected to the driving means, the axis of said shaft being located in a plane parallel to the normal plane of the driven disk, a friction wheel longitudinally movable upon the shaft and frictionally engaging the adjacent side of the driven disk. and torsion spring and screw means connecting the friction wheel and the shaft for moving the friction wheel toward and from the center of the driven v disk to compensate for variations in drag and resultant speed changes of the driven disk.

2. A transmission including a driving means, a driven disk, a shaft operatively connected to the driving means and located radially relative to the driven disk, a friction wheel longitudinally movable upon the shaft and frictionally engaging the adjacent side of the driven disk, and torsion spring and screw means connecting the friction wheel and the shaft for moving the friction wheel radially upon the drivendisk to compensate for variations in drag and resultant speed changes o the driven disk.

3. A transmission including a driving means, a driven disk, a shaft operatively connected to the driving means and located radially relative to the driven disk, a friction wheel threaded upon the shaft and frictionally engaging the adjacent undersurface of the turntable near the periphery thereof.

As the motor 22 is operated, the friction pulley 25 drives the friction wheel 3| and shaft 21, and through the spring 43 the friction wheel 36 is rotated, driving the turntable at proper speed.

In the operation of the phonograph, as the pressure of the needle upon the record, carried by the turntable, offers resistance to the rotation of the turntable, the spring 43 will be wound upon itself rotating the movable friction Wheel 36 upon the shaft in a direction whereby the screw threads 39-40 cause the wheel 36 to move longitudinally on the shaft toward the center of the turntable, bringing the tire 31 of the wheel 36 into contact with the turntable at a point closer to the center thereof.

side of the driven disk, stop means upon the shaft for limiting the movement of the friction Wheel in one direction, and a. torsion spring connected to the friction wheel and to the shaft for urging the friction wheel toward the stop means, so that the friction wheel is moved radially relative to the driven disk by variations in drag to compensate for resultant variations in speed of the driven disk.

4. A transmission including a driving means, a driven disk, a shaft operatively connected to the driving means and having a spiral groove therein, said shaft being located radially relative to the driven disk, a friction wheel longitudinally movable upon the shaft and having an internal, spiral rib received in said spiral groove, said friction wheel frictionally engaging the adjacent side of the driven disk, and a torsion spring connected to the friction wheel and to the shaft for moving the friction wheel radially upon the driven disk to compensate for variations in` drag and resultant speed changes of the driven disk.

EMMOR V. SCHNEIDER.

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