US2174156A

US2174156A - Phonographic apparatus

Info

Publication number: US2174156A
Application number: US187936A
Authority: US
Inventors: Emile C Guedon
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1938-01-31
Filing date: 1938-01-31
Publication date: 1939-09-26
Anticipated expiration: 1956-09-26

Description

E. c. GU EDON PHONOGRAPHIG APPARATUS Sept. 26, 1939.

FiledJan. 31, v 1938 Patented Sept. 26, 1939 UNITED STATES PATENT OFFICE 2,174,156 PHONOGRAPHIO APPARATUS of Delaware Application January 31, 1938, Serial No. 187,936

8 Claims. This invention relates to phonographic apparatus, and more particularly to a pick-up supporting arm and mounting therefor.

In the reproduction of sound from a phonographrecord, it has been recognized that, for best results, the needle pressure on the record should be constant at all times. With conventional pick-up arm mountings heretofore in use, this has not been possible for the reason that most records, particularly those of the dis'ctype, are more or less warped and cause vertical movement of the pick-up arm as it travels over the record. This vertical movement results in friction at the supporting bearing for the pick-up arm which alters the needle pressureon the record and therefore prevents best results from being obtained. 4

The primary object of my present invention is to provide an improved pick-up arm and mounting therefor which will be free from the foregoing difficulty.

More specifically, it is an object of my present invention to provide an improved pick-up arm and mounting which will be free to oscillate in a vertical direction in response to distortions in the record without introducing any bearing friction.

Another object of my present invention is to provide, in-a pick-up arm and support as aforesaid, an improved means for adjusting the pressure of the needle upon the record.

It is also an object of my present invention to provide a construction of the type set forth which is comprised of a minimum number; of parts,

the requirements of economic facture.

In accordance with my present invention, I provide a bushing, or bearing member, having inner and outer bearing surfaces, and mount in the inner surface a shaft to which the pick-up supporting arm is fixed for movement therewith bell crank arm presses against the pick-up sup.-

which is economical in cost, which is highly efficient in use, and which readily lends itself toquantity manuasa unit. Upon the outer surface of this bearporting arm, whereby to permitready adjustment of the needle pressure upon therecord.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The inventionitself, however, both as to its organization and method of operation, together with additional objects and advantages thereof, .will best be understood from the following description of one embodiment thereof, when read in connection with the accompanying drawing in which Figure 1 is a .view partly in plan and partly in section of a pick-up arm and mounting formed according to my present invention,

Figure 2 is a central sectional view thereof, Figure 3 is a sectional view of the mounting taken on the line III-'-III of Fig. 1 and Figure 4 is a rear elevation of my improved pick-up arm.

Referring more particularly to the drawing, wherein similar reference characters designate corresponding parts throughout, there is shown a motor board I provided with an opening 3. throughwhich extends a hearing device 5 secured in any suitable manner to the motor board I. Pivotally carried bythe bearing 5 is the shaft 1 of a bracket member 9v having a pair of upstanding standards II from which project a pair of spaced arms l3 constituting a forwardly extending bifurcated portion, the forward ends of the arms l3 being connected by a cross piece I5.

The standards H are spaced from each other,

asclearlyshown in Fig. 3, and are provided with aligned openings adjacent their upper ends for the reception of a hollow bearing member or bushing H. The inner bearing surface of the bushing l1 pivotally carries a shaft comprised of a sleeve I 9 which-is preferably I-shaped in cross section and to which is suitably secured a pin 2|, the sleeve l9 and the pin 2| being one integral unit. The ends of the pin 2,| extend slightly beyond the ends of the sleeve l9 and are received in aligned openings adjacent one end of a pick-up supporting arm 23 which extends forwardly in the same direction as the arms l3 but is considerably longer than the latter arms, the pick-up 'arm 23 carrying a pick-up provided with a needle 25 which is held in place by a screw 21 in conventional manner. The ends of the pin 2| are headed over to provide rivet heads: 29 by means of which the pick-up supporting arm 23 is securedto the pin 2| and the sleeve IQ for pivotal movement therewith as a unit withinfthe bearing member I! and in a plane normal to the plane in which the base of the bracket 9.pivcts in the bearing 5.

Pivotally mounted on the outer bearing surface of the bearing member or bushing H between the standards II is a bell crank 3| having a forwardly extending arm 3: and a pair of downwardly extending arms 3lb and 3lc. The arm 3i'a. of the bell crank is arranged to engage the pick-up supporting arm 23 in the manner shown in Fig.2 and is constantly urged to this position by a coil spring 33 one end of which is secured to the arm 3lb and the other end of which is secured to a screw 35 received in an opening in the. cross piece i5 and held in adjusted position by means of a notched nut 31 in cooperation with a wedge 39 on the cross piece. l5. By manipulating the nut 31- to adjust the tension of the spring 33, the force with which the arm 3|a of the bell crank engages the pick-up supporting arm 23 may. be readily controlled to vary the pressure of the needle 25 on a phonograph record H. A vertically extending screw 43 carried by the bracket member 5 cooperates with the pickup arm 23 to limit the upward movement thereof with respect to the record 4|, and a screw 45, also threaded into the bracket member 9, serves, by cooperation with the arm 3Ic of the bell crank, to limit the downward movement of the pick-up arm.

From the foregoing description, it will be apparent that I have provided a novel pick-up arm mounting by means of which the pick-up arm is free to move in a vertical direction on the inner bearing surface of the bushing [1 without in any Way being affected by the force applied to the outer bearing surface of the bushing l'l through the spring 33 and the bell crank 3|. Since there is no variation of the frictional forces generated upon pivotal movement of the pick-up arm 23 and its supporting shaft i9-2i within the bushing 11, it will be apparent that the pressure of the needle upon the record, once it has been adjusted by means of the nut 3], always remains the same. It will also be apparent that my improved pick-up arm mounting'afiords a ready and effective means for varying theneedle pressure when desired.

Although I have shown and. described but one embodiment "of my invention I am fully aware that many other modifications thereof are possible, and I therefore desire that my invention her having a plurality of bearing surfaces, said 'arm being pivotally carried by one of said bearingsurfaces, means pivotally carried by another of said bearing surfaces and arranged to press against said arm to relieve the weight thereof on a record, and means for-adjusting the pressure of said first-named means on said arm whereby 'to regulate the needle pressure of the pick-up on the record.

2. In phonographic apparatus, the combination of a pick-up supporting arm, means pivotally mounting said arm for movement across a record, abearing carried by said means and having a plurality of bearing surfaces one of which carries said arm for movement in a direction normal to said first-named movement, and

means pivotally carried by another of said bearing surfaces arranged to press against said arm to relieve the weight thereof on a record.

3. In phonographic apparatus, the combination of a bracket, a hollow bearing member carried by said.bracket, a shaft rotatably mounted within said bearing member, a pick-up supporting arm carried by said shaft, a bell crank pivotally mounted on the outer surface of said bear,-

ing member and having an arm adapted to engage said pick-up supporting arm, and means constantly urging said bell crank arm into engagement with said pick-up supporting arm.

4. In phonographic apparatus, the combination of a bracket, a hollow bearing member carried by said bracket, a shaft rotatably mounted within said bearing member, a pick-up supporting arm carried by said shaft, a bell crank pivotally mounted on the outer surface of said hearing member and having an arm adapted to engage said 'pick-up supporting arm, means constantly urging said bell crank arm into engagement with said pick-up supporting arm, and means for adjusting said last-named means whereby 'to vary the force applied by said bell crank arm against said pick-up supporting arm.

5. In phonographic apparatus, the combination of a bracket having a forwardly extending portion, a hollow bearing member carried by said bracket, a shaft rotatably mounted within said bearing member, a pick-up supporting arm carried by said shaft and movable therewith as a unit, a pick-up carried by said arm, a bell crank pivotally mounted on the outer surface'of said bearing member and having an arm adapted to engage said pick-up supporting ,arm, and spring means connecting said bell crank with said forwardly extending bracket portion constantly urging said bell crank arm into engagement with said supporting arm to relieve =the weight of said supporting arm and its pick-up from a record.

6. Inphonographic apparatus, the combination of a bracket having a forwardly extending portion a holow bearing member carried by said bracket, a shaft rotatably mounted within said bearing member, an elongated pick-up supporting arm fixed adjacent one end thereof to said shaft for movement therewith as a unit, said pick-up supporting arm extending forwardly of said bracket a distance greater than and in substantial alignment with said forwardly extending bracket portion, a pick-up carried by said arm at its forward end, a bell crank pivotally mounted on the outer surface of said bearing member and having a forwardly extending arm adapted to engage said pick-up. supportingarm, and spring means connecting said bell crank with said forwardly extending bracket portion constantly urging said bell crank arm into engagement with said supporting arm to relieve the weight of said supporting arm and its pick-up from a record.

'I. The invention set forth in claim 6 characterized by the addition of means for adjusting the tension of said spring means whereby to vary the force applied by said bell crank arm against said pick-up supporting arm.

8. The invention set forth in claim 6 characterized in that the forwardly extending portion of said bracket is bifurcated, and characterized further in that said bell crank and said spring means are disposed between the arms constituting the bifurcation.

' GUEDON.