US2254454A

US2254454A - Electric phonograph pickup

Info

Publication number: US2254454A
Application number: US282876A
Authority: US
Inventors: Jr Charles E Semple; Frank J Malat
Original assignee: Astatic Corp
Current assignee: Astatic Corp
Priority date: 1937-07-08
Filing date: 1939-07-05
Publication date: 1941-09-02
Anticipated expiration: 1958-09-02

Description

p 1941- c. EfSEMPLE, JR., ETAL 4,454

ELECTRIC PHONOGRAPH PICKUP Original Filed July 8, 1937 CHARLES E-6EM PLE JR. FRAN K J, MALAT iwf'wv y Patented Sept. 2, 1941 ELECTRIC PHONO GRAPH PICKUP Charles E.- Semple, Jr., and Frank J. Malat, Youngstown, Ohio, assignors to The Astatio Corporation, a corporation of Ohio Original application July 8, 1937, Serial No.

152,550, now Patent No. 2,182,138, dated Decem- Divided and this application July 5, 1939, Serial No. 282,876 2 7 Claims. (Cl. 179-10041) This application is a division of original application Serial Number 152,550, filed July 8, 1937, now Patent No. 2,182,138, issued Dec. 5, 1939. The present invention relates to the art of sound reproduction and more particularly to means for operatively supporting the translating device for converting the mechanical impulses caused by the moving record into electrical impulses suitable for use in electrical phonographs. Such supporting means are commonly termed pick-up arms and are so constructed that the stylus or needle of the translating device may rest in the groove of the record and move across the face of the record as the record rotates.

The arms for supporting the stylus or needle of the translatingrdevice are usually mounted adjacent their outer ends for pivotal movement about horizontal and vertical axes whereby the stylus or needle is allowed to follow the undulations on the record face and move from the outer periphery of the record towards the center along the spiral groove as the record rotates. The arms are'counterweighted to balance the weight of the portion overreaching the record and the Weight of the translator mounted at the end of the arm. It is common practice to house and support the translator in a separate housing or casing which is attachable to the end of the arm. The primary object of the invention is the provision of an improved reconstruction for the housing and immediate support of the translating device.

Another object of the invention is to provide such a support in which the vertical plane of the needle is caused to assume a good average tangency with the curve of the groove of the record as the needle moves across the record and in which the support may be readily rotated to facilitate the insertion and removal of the needle.

A further object of the invention is the provision in an assembly of the character described of an improved means to swivably support the immediate translator housing and support on the end of the counterbalanced arm whereby the translator housing and support is held in selected rotated position and its rotation limited to prevent undue twisting of conductor cords extending from the translator back through the arm.

A still further object of the invention is the provision of an improved construction for the arm proper.

These and other objects and advantages of the invention will become apparent from a considerationof the drawing and the following detailed description wherein there is specifically disclosed a preferred embodiment of the invention.

In the drawing: v I

Figure 1 is a plan View of a pick-up arm constructed in accordance with the invention;

Figure 2 is a side view, partly in section, of the arm of Figure 1;

Figure 3 is a bottom view of the assembled translator and housing therefor of the arm of Figures 1 and 2;

Figure 4 is an end view ing and support; and

Figure 5 is a perspective view of a sleeve used in the construction of the preferred embodiment.

Referring to the drawing wherein the same reference numerals are used f to designate the same parts throughout the various views, the pick-up arm of the invention consists generally of a translator housing and support [0, a, tubular central member 20 and a weighted end member 30. In' accordance with usual practice, the arm is movable about both horizontal and vertical axesand for this purpose a base 40, adapted to be fastened to a suitable surface of the cabinet structure with which the arm may be associated, is provided and an arm 48 is pivotally mounted on the base 40 for movement about a vertical axis. To the outer end of arm 48 a pick-up arm is pivotally mounted by means of the horizontal pin 53, thus providing for movement of the pickup arm about a horizontal axis.

The weighted end member 38 of the pick-up arm consists preferably of a square block of metal having an integral rounded shank 3| to fit within an end of the tubular member 20. C'ap screws 25 passing through apertures in the tube 20 and threaded into bores provided in the shank 3| provide a rigid connection between the tube 20 and the block 30. The other end of the tubular member 20 rotatably supports the translator housing [0 which is provided with a shank I3 fitting within the end of the tubular member 20. Shank [3 extends from an angularly disposed side portion I2 of the housing H] and extending axially outward of the shank l3 and the adjacent wall of the housing is a tubular member l4 held within the bore of the shank and the wall by the set screw I5. A fixed pin I! and a second pin I8 spring pressed outwardly by the coil spring I9 are positioned diametrically opposite on the shank I3 radially outward of the tube M.

A bushing 2| of Bakelite or other suitable material is secured within the tube 20 by the screw 29 and, as shown more clearly in Figure 5, an end of the bushing, which when the parts are asof the translator houssembled is adjacent the pins |l--l8, is cut away at 22 for a portion of its periphery to provide a 7 and has its end swaged over at I6 to secure the V bushing and head together.

With the head in operative position both pins.

are within the cut away portion 22 engaging both shoulders 23 and 23' to hold the headiin' position. If the head is now'rotated to change the needle or for other purposes, the spring pressed pin [8 rides over the inclined shoulder 23' and frictionally engages the' end surface of the bushing. The rotation'of the head is; lim- 'lel with the axis of rotation of said head and a shank fitting within the free end of said member, a translating device within said head, a

bushing secured within said tubular member,

said bushing, a pair of circumferentially spaced pins in said shank extending in a direction paraladapted to engage the adjacent end of said bushited by the engagement of pin I! with shoulder.

23'. Thus any excessive twisting of .the. conductor 41 is prevented. The frictional engagement of the pin l8 with the end of the bushing holds the head in rotated position while the needle is being changed;

A plate I5 and screws 6 clamp the cartridge H to the side wall of the head. The translating cartridge H is provided with a needle receiving socket 1 and a set screw 8 to engagethe needle and hold it rigidly in the socket. Thumb and finger engaging members 9 are provided to facili tate rotation of the head. 7

As shown in. Figures 1 and 3 the cartridge and the plane of the needle carried thereby is disposed at an angle to the longitudinalaxis of the arm. This arrangement enables the vertical plane of the needle to assume a good average tangency with the curve of the groove of the record, resulting in better reproduction and decrease in wear of the record and needle. It should also be observed that a vertical plane. passing through the longitudinal axis of the arm 2ll+30 passes substantially through the rec- 0rd engaging end of the stylus carried by the translator cartridge II, which arrangement obviates the tendency of the casing [0 to rotate about the longitudinal axis of the arm due to the weight of the casing and the arm supported by the stylus. In practice the parts arefitted with such accuracy that the translator casing ID will not vibrate independently of the arm as a whole. 7 7

It should now be apparent that we'have provided improved features in the construction of a pick-up arm which accomplishes the objects initially set. out. The stylus supporting means carried by the end of the arm is so arranged that the vertical plane ofthe stylus is caused to assume a good average 'tangency with the curve of the groove of the record with which the arm and translator is intended to be associated, while enabling the means to be readily rotated to facilitate theginsertion and removal of the stylus or needle. The structural features of the arm as a whole, including the use of the block 30, results in a well balanced, rugged and easily constructed device'which' in practice has been found to produce excellent results in the reproduction of sound from the records. The above specifically described embodiment of the invention should be considered as illustrative only as obviously many changes maybe made therein'without departing from the spirit or scope .of' the invention. v

What we claim is: r v j i 1.A pick-upv arm' comprising a swingably mounted tubular member, a hollow head having means to urge the same outwardly, one shoulder of said cut-away portion being inclined whereby the spring pressed pin may override the same.

2. A pick-up arm comprising a swingably .mounted tubular member, a rigidly mounted non-metallic bushing within said member adjacent the free end thereof, a tube rotatably mounted within said bushing and extending beyond the free end of said tubular member, means to prevent outward longitudinal movement of said tube, a carrier for a translating device rigidly secured to the outer extended end of said tube, and means limiting the relative rotation between said carrier and said bushing.

3. A pick-up arm comprising a swingably mounted tubular member, a rigidly mounted bushing in said member adjacent the free end thereof, a tube rotatably mountedwithin said bushing and extending beyond the free end of said tubular member, means to prevent outward movement of said tube, a carrier for a translating device rigidly secured to the outer end of said tube, the outer end of said bushing being provided with a depressed portion having an inelined shoulder, a rigidly mounted projection and a spring pressed projection extending from said carrier and adapted to enter said depressed portion, the inclined shoulder enabling said spring pressed projection to ride out of said depressed portion upon rotation of said carrier.

7 4. A pick-up arm for an electric phonograph comprising in combination an elongated block of heavy material having a boss extending from one end thereof, means to pivotally support said block adjacent said boss for movement about a horizontal axis, a tubular member having one of its ends fitting over said boss, a housing for a translating element swivably mounted on the other end of said tubular member for rotative movement about the longitudinal axis of said tubular member, said housing having an extended portion obliquely positioned with respect to the longitudinal axis of said tubular member, the translating element comprising a casing inclosing a piezo-electric crystal and a needle support being received in said extended portion and being provided with a record engaging needle lying in a vertical plane passing through the center of said extended portion. 5. A pick-up army for an electric phonograph comprising in combination a generally horizonthe longitudinal axis of said arm, said housing comprising spaced parallel side Walls extending obliquely with'respect to said axis, a translating device comprising a casing. enclosing a piezoelectric crystal and a needle support adapted to be received between said walls, means to seplate and means to clamp said plate to one of the side walls of said housing with said casing thereinbetw'een.

'7. A device according to claim 5 further in- 5 eluding a manually engageable knob on the outer side of each of said Walls to facilitate relative manipulation of said housing.

CHARLES E. SEMPLE, JR. FRANK J. MALAT.