US1892322A - Device playing records with a constant linear speed - Google Patents

Description

Dec. 27, 1932. $A|NT 1 1,892,322

DEVICE PLAYING RECORDS WITH A CONSTANT LINEAR SPEED Filed March 2, 1952 GA 12R Patented Dec. 27, 1932 PATENT OFFICE GEORGES SAINT MARTIN, F PARIS, FRANCE DEVICE PLAYING RECORDS WITH A CONSTANT LINEAR SPEED Application filed March 2, 1932, Serial No. 596,321, and in France March 17, 1931.

My invention relates to devices playing records with a constant linear speed. It is known that with these records over which the needle moves along the sound track through equal lengths for equal durations, it is possible to provide for the same diameter of the record a much longer time of recording or playing, whereby they show a considerable interest in particular for synchronizing a kinematographic projection with a sound-producing apparatus. Of course it is necessary that during the playing of a record recorded at constant linear speed, the speed should be equal to that used in the recording. Now it is of interest to obtain this result with an ordinary phonograph wherein the turntable is driven with a constant angular speed.

My invention has for its object a simple device affording means for playing on an ordinary phonograph a record which has been recorded at a constant linear speed. This device comprises chiefly a lag-providing part driven by the sound reader i. e. the diaphragm or pick-up of the phonograph. This part may in particular rook round a vertical spindle integral with the sound reader and is adapted to brake more or less the movement of the record whereby the acoustic groove will advance under the needle at a constant or substantially constant linear speed.

I have shown in accompanying drawlng a form of execution of my invention wherein:

Fig. 1 is a side view of the device,

Fig. 2 is a plan view thereof.

To the diaphragm-carrying sound box 1 of an ordinary phonograph provided with the usual needle 2 and carried by the sound arm 3 is permanently secured a support 4:. This support shows an enlargement 5 provided with a vertical perforation engaged by a spindle 6 the upper end of which forms a head 7. A casing 8 is provided with two apertured bosses 9 and 10 through which the spindle 6 passes on either side of the enlargement 5. The casing 8 may thus rotate round this spindle and moreover move vertically with reference to it, by reason of the play existing between the enlargements or bosses 5, 9 and 10.

The lower part of the casing 8 carries a wheel'll made of material having a large frictional power when rubbing against the record material whereby it may roll over the surface of the latter without slipping. This wheel drives as it rotates a pinion 12 mounted on the same shaft. This pinion meshes with .a worm 13 carried by a vertical shaft provided with a centrifugal regulator 15 of the type commonly used in phonographs. The movable part of the regulator carries a plate 17 which rubs when the weights move apart against the friction plates 18 carried by the casing 8 whereby a braking action is provided.

It is apparent that the casing, heavy enough to provide adherence, is carried freely by the record and follows the needle 2, the wheel 11 remaining exactly in the track of said needle and rotating round its axis as soon as the record rotates by reason of its frictional contact therewith. 5

The record driven by the motor at constant angular speed has a tendency to rotate too rapidly. It drives therefore the wheel 11 at a speed such that the regulator 15 becomes operative. As they move apart the regulator weights bring the plate 17 against the friction plates 18 with an energy which is greater as the angular speed is greater. This brakes the wheel 11 which in its turn brakes the record as the latter cannot slip with reference to the wheel 11.

Through a suitable adjustment of the brake which may be effected through a knob 19, I may give at each moment a speed such to the record that the sound line moves under the needle 2 with a substantially constant linear speed.

Owing to the freedom of rotation of the casing 8 round the spindle 6, the wheel 11 may always come into a plane tangent to the sound line and thus run under satisfactory conditions. The case would be different with any lag-producing system if this pivotal connection did not exist as the wheel would work under bad conditions and urge the sound arm sideways.

That I claim is:

1. A device for decreasingly braking a record driven at constant angular speed for making the sound groove advance at a constant linear speed comprising in combination the sound arm, the needle carried by it, a casing pivotally secured to the sound arm and adapted to move vertically with reference thereto, a wheel carried by the casing and adapted to roll over the record surface without slipping with reference thereto to the rear of the needle, a centrifugal regulator carried by the casing and driven by the wheel and means controlled by the regulator for damping the movementof the wheel and thereby of the record with an energy increasing with the speed of the wheel.

2; A device. for decreasingly braking a record driven at constant angular speed for making thesound groove advance at a constant linear speed comprising in combination the sound arm, the needle carried by it, a support carried by the sound arm and including a vertically bored outer part, a casing, two vertically bored lugs on said casing spaced above one another through a height greater than that of said outer part and disposed on' either side thereof, a spindle passingthrough the lug bores and the bore in the outer part of the support, a Wheel carried by the casing and adapted to roll over the'record surface without slipping with reference thereto to the rear of the needle, a centrifugal ball regulator carried by the casing and driven by the wheel and friction plates against which the regulator balls rub with an energy increasing with the speed of the wheel. 7

In testimony whereof I have edited my signature.

GEORGES SAINT MARTIN.

Images