US2247659A - Phonographic apparatus - Google Patents

Description

Jill??? 11%? J. J. HOEHN 2,247,659

PHONOGRAPHIC APPARATUS Filed May 7, 1940 2 Sheets-Sheet I 3nventor J. J. HOEHN PHONOGRAPHIC APPARATUS 2 Sheets-Sheet 2 Filed May 7, 19 .0

EG- J.

Patented July 1, 1941 2,247,659 PHONOGRAPHIC APPARATUS John J. Hoehn, Indianapolis, Ind., assignor to Radio Corporation of America, a corporation of Delaware Application May 7, 1940, Serial No. 333,705

6 Claims.

This invention relates to phonographic apparatus, and more particularly to apparatus for recording sound upon a record disc for immediate reproduction from the record.

It is well known that, in apparatus of this sort, the load imposed upon the record blank by the cutter when a sound groove is being recorded is much greater than the load imposed upon the reproducing needle when the finished record is being reproduced. Under ordinary circumstances, the additional load imposed by the recording stylus is usually suflicient to cause slippage of the record blank upon the turntable which supports it, and as a consequence, there results distortion in the recording. To obviate this, it has been proposed to provide the turntable with one or more eccentric driving pins which are adapted to be received by corresponding openings in the record blank to provide a positive drive for the record and to prevent slipping thereof relative to the turntable. Obviously, this limits the use of such a turntable only to records which are provided with openings corresponding to the eccentric driving pins on the turntable. It is usually desirable, however, to also reproduce standard records by means of the same apparatus, the conventional standard records having no eccentric openings for receiving the aforementioned eccentric driving pins.

The primary object of my present invention is to provide an improved phonographic apparatus wherein the aforementioned difficulty is avoided.

More particularly, it is an object of my present invention to provide improved phonographic apparatus by means of which it will be possible to record upon and reproduce from records of both the standard type and the type having eccentric openings therein as aforementioned.

Another object of my present invention is to provide an improved phonograph turntable which is adapted to receive both standard and special records as aforementioned and which can be arranged for this purpose with great facility.

Still another object of my present invention is to provide an improved turntable as aforesaid which is simple in construction andinexpensive to manufacture.

In accordance with my invention, I provide in the turntable hub a pair of eccentric bores which extend longitudinally therethrough. In one of said bores, I provide a driving pin which is normally biased by a suitable spring to an elevated position such that it protrudes above the recordsupporting surface of the turntable, the said driving pin being depressible under the weight of a standard record against the action of the spring into a lowered position where the top of the driving pin is substantially flush with the record-supporting surface of the turntable. When so lowered, the lower end of the driving pin projects through the bottom of the turntable and exposes an annular groove therein into which a leaf spring, secured to the bottom of the turntable hub, is adapted to slide and which acts as a detent to releasably lock the driving pin in lowered position. In the second of the aforementioned bores is a plunger the lower end of which is formed with a cone constituting a cam element which rests against the aforementioned leaf spring, and the action of said leaf spring on the cone normally holds the plunger in elevated position such that the tip of the plunger is slightly below the record-supporting surface of the turntable. When the plunger is depressed, the cone or cam element thereon bears against the leaf spring and forces it out of the annular groove in the driving pin, whereby the coil spring associated with the driving pin becomes free to raise the driving pin into its elevated position in readiness to be received in the eccentric opening of a special record.

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 embodiment thereof, when read in conjunction with the accompanying drawings wherein Figure 1 is a fragmentary top plan view of a phonograph turntable embodying one form of wherein similar reference numerals indicate cor-' responding parts throughout, I have shown a turntable l provided with the usual hub 3 having a central bore through which extends a motor shaft terminating in the conventional recordcentering spindle 5. The hub 3 is also provided with a pair of bores l and 9, and within the bore l is mounted, for longitudinal movement therein, a driving pin ll formed with an annular groove l3. and having secured thereto a pair of fixed collars or washers l5 and IT. A coil spring l9, surrounding the driving pin II and interposed between the collar [5 and a shoulder 2| formed in the bore 1, tends constantly to raise the driving pin it to the elevated position shown in Fig. 2, wherein the driving pin extends above the record-supporting surface of the turntable to en-' gage the eccentric opening 23 of a record blank R of the special type. It is obvious, therefore, that the driving pin Ii will provide a positive drive for the record R when in raised position.

If desired, a mat 25 of rubber, felt, or the like,

may be provided as a facing orcovering for the turntable to provide good frictional contact between the turntable l and the record blank R when a standard record is used on the turntable I.

Mounted for longitudinal movement in the bore 9 is a rod or plunger 21 formed with a cone 29 on its lower end, the cone 29 being received between and resting upon the arms 3la of a U- shaped or hairpin-shaped leaf spring 3| secured to the bottom of the hub 3, as by means of a screw 33. The spring 3| is so formed that the arms am thereof constantly tend to move toward each other in the directions of the arrows A (Fig. 4) and, acting on the cone 29, the spring 3| constantly tends to hold the plunger 21 in elevated position wherein the upper tip of the plunger-21 is slightly lower than the record-supporting sur-. face of the turntable. The spring arms 3|a also straddle the lower end of the driving pin II and act as a stop against which the collar I1 bears in the elevated position of the driving pin l I.

When a record of the special type heretofore mentioned is to be used on my improved turntable, the driving pin is permitted to remain in the position shown in Fig. 2' and the protruding upper end of the driving pin II is received in the eccentric opening 23 of the special record. If it is desired to play a standard record,'al1 that is necessary is to thread the record on the centering spindle 5, the record thereupon resting on the upper end of the driving pin II and causing it to be depressed into its lower position, as shown in Fig. 3, the weight of the record being sumcient to overcome the force of the spring l9. When this is done, the side arms 3la of the detent sprin 3|, moving in the directions of the arrows A (Fig. 4), automatically slip into the groove I3 and releasably lock the driving pin H in its lowered position, as shown in Fig. 3. If, thereafter, it is desired to either record upon or reproduce from a special record as aforementioned, the plunger21 is depressed, whereupon the cam element or cone 29 forces the arms 3la of the spring 3| apart in the directions of the arrows B and into the dotted line position of Fig. 4 to disengage the arms 3la from the annular groove l3, whereupon the spring 19 immediately raises the driving pin H to its elevated position again.

From the foregoing description, it will be apparent to those skilled in the art that I have provided a novel and improved turntable which is adapted to accommodate records of both the standard type and the special type. Although I have shown and described but one embodiment of my invention, it will be apparent to those skilled in the art that many other modifications are possible. For example, instead of using merely one eccentric driving pin, I may provide several such pins and associated mechanisms around the centering spindle 5 and either on the same radius or at difierent radii. Many other changes will, no doubt, readily suggest themselves to those skilled in the art. I, therefore, desire that my invention shall not be limited except insofar as is made necessary by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. In phonographic apparatus, a turntable for supporting a record in operative position, said turntable including a driving pin arranged eccentrically with respect to the turntable center and adapted to be received in a corresponding eccentric opening in the record to provide driving engagement therewith, said driving pin being movably mounted on said turntable for movement between an elevated position wherein said driving pin extends above the record-supporting surface of said turntable and a lowered position wherein the tip of said driving pin is substantially flush with said surface, yieldable means constantly urging said driving pin to said elevated position, said means being adapted to yield under the weight of a-record on said turntable whereby to effect lowering of said driving pin-to said lowered position when a record is placed thereon which has no corresponding eccentric opening to receive said pin, and means for releasably locking said driving pin in said lowered position. v

2. In phonographic apparatus, a turntable for supporting a record in operative position, said turntable including a driving pin arranged eccentrically with respect to the turntable center and adapted to be receivedin a corresponding eccentric opening in the record to provide driving engagement therewith, said driving pin being movably mounted on said turntable for movement between an elevated position wherein said driving pin extends above the record-supporting surface of said turntable and a lowered positionwherein the tip of said driving pin'is substantially flush with said surface, yieldable means constantlyurging said driving pin to said elevated position, said means being adapted to yield under the weight of a record on said turntable whereby to effect lowering of said driving pin to said lowered position when a record is placed thereon which has no corresponding eccentric opening to receive said pin, means for releasably locking said driving pin in said lowered position, and means for releasing said locking means to render said yieldable means free to elevate said driving pin to said elevated position.

3. The invention set forth in claim 1 characterized in that said turntable is provided with a bore eccentric to the turntable center, characterterized in that said turntable is provided with a bore eccentric to the turntable center, characterized further in that said driving pin is mounted in said bore for longitudinal movement therein, characterized further in that said driving pin is provided with a groove at a portion therein which extends below said turntable ,whensaid pin is depressed into said lowered position, and characterized still further in that said locking means comprises a leaf spring secured to the bottom of said turntable and biased toward said pin whereby said leaf spring is adapted to slip into said groove when aid pin is lowered to thereby releasably lock said pin in said lowered position.

5. The invention set forth in claim 2 characterized in that said locking means comprises a movably mounted detent movable into locking engagement with said driving pin, and characterized further in that said means for releasing said detent includes a cam arranged to engage said detent to force it out of locking relation with said driving pin.

6. The invention set forth in claim 2 characterized in that said turntable is provided with a pair of bores each eccentric to the turntable center, characterized further in that said driving pin is mounted in one of said bores for longitudinal movement therein, characterized further in that said driving pin is provided with a groove at a point therein which extends below said turntable when said pin is depressed into said lowered position, characterized further in that said locking means comprises a leaf spring secured to the bottom of said turntable and biased toward said pin whereby said leaf spring is adapted to slip into said groove when said pin is lowered to thereby releasably lock said pin in said lowered position, and characterized still further in that said means for releasing said locking means comprises a plunger mounted for longitudinal movement in the second of said bores, said plunger including a cam element normally resting on said leaf spring and said leaf spring normally holding said plunger in elevated position on said turntable by engagement with said cam element, and

said cam element being adapted to force said leaf spring out of said driivng pin groove to release said driving pin and permit said yieldable means to raise said driving pin to said elevated position.

JOHN J. HOEHN.

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