US2768245A - Stylus-holding chucks for phonograph pick-up cartridges - Google Patents

Description

Oct. 23, 1956 M. PALO STYLUS-HOLDING CHUCKS FOR PHONOGRAPH PICK-UP CARTRIDGES Filed March 31 1951 2 Sheets-Sheet 1 INVENTOR MAURICE PALO ATTORNEY M. PALO Oct. .23, 1956 STYLUS-HOLDING CHUCKS FOR PHONOGRAPH PICK-UP-CARTRIDGES Filed March 31 1951 2 Sheets-Sheet 2 gal ii QHEQ MEMM

INVENTCR MAURICE PAL BLANK 2 1: 29

BY ATTORNEY United States Patent STYLUS-HOLDING CHUCKS FOR PHONOGRAPH PICK-UP CARTRIDGES Maurice Palo, Conneaut, Ohio, assignor to The Astatic Corporation, Conneaut, Ohio, a corporation of Ohio Application March 31, 19%, Serial No. 218,692

1 Claim. (Cl. 179-10041) This invention relates to phonograph pick-up devices and more particularly to an improved stylus-holding chuck for pick-up cartridges and to improve methods of making the same. As will be understood, phonograph pick-up cartridges are usually formed with the casing housing a mechanical-electrical transducer and mounting a chuck or driving element which is operative to receive and retain a record-engaging stylus and to transmit the motion thereof to the transducer. The present invention provides an improved driving chuck which, while capable of being mass produced at low cost, is operative to provide a more efiicient means for mounting and retaining the stylus and for driving the transducer. More specifically, the inventi'on provides an improved stylus-holding chuck which is capable of being easily mounted in the pick-up cartridge casing in a manner designed to transmit the undulations of the record groove to the transducer with greater fidelity, and which is provided with inherent means to releasably retain the record-engaging stylus. Secondarily, the improved stylus holder of my invention is capable of being rapidly and efficiently formed from a single piece of sheet metal and is capable of simultaneously mounting a pair of record-engaging stylii which is desirable in some applications.

Another object of the invention is the provision, in a phonograph pick-up cartridge, of an improved stylusholding chuck and of an improved arrangement for mounting the chuck in the cartridge casing and relative to the transducer element whereby undesirable noise transmission is minimized without impeding the fidelity of transmission of the desired sound and whereby the transducer element and the physical connection between the driving chuck and the transducer element are protected against damage in case the pick-up head i accidentally dropped on a record surface, for example.

A further object of the invention is the provision of an improved driving chuck for a phonograph pick-up cartridge which is capable of being mass produced in an economical manner by an automatic stamping process and which may readily bevaried in design toeffecta different coupling with the transducer element while yet requiring only minor changes in the set up of the automatic progressive die utilized to produce the part.

The above and other objects and advantages of the invention will become apparent upon consideration of the following detailed specification and the accompanying drawing wherein there is disclosed certain preferred embodiments of the invention.

In the drawing:

Figures 1. and 2 are horizontal and vertical sections, respectively, of the stylus end of a phonograph pickup cartridge utilizing the improved driving chuck of my invention;

Figures 3 and 4 are horizontal and vertical sections of a modified form of pickup cartridge utilizing a modifying form of driving chuck of my invention;

Figures 5" and 6 are enlarged perspective views of the Patented Oct. 23, 1956 driving chucks utilized in the assemblies of Figures 1 and 3, respectively;

Figures 7 and 8 are plan and side views, respectively, of a stock strip utilized in the production of the chuck of Figure 5 and showing the various successive stages of forming therein by a progressive die, not shown; and

Figures 9 and 10 are views similar to Figures 7 and 8 but showing the progressive formation of the chuck of Figure 6.

Referring to the drawing in detail it will be noted that in accordance with usual practice the phonograph pickup cartridge illustrated is housed in two mating casing sections 10 and 11 which when assembled are operative to contain a pieZo-electric crystal element 12. As is well understood in the art it is common practice to clamp one end, not shown, of this element between resilient pads, also not shown, cemented to the inner surfaces of the casing sections 10 and 11 while the other end of the element is freely disposed and thus capable of being flexed whereby the element may be bent or twisted to generate an electrical potential proportional to the extent of flexing. The present invention is concerned with a bending type crystal as distinguished from the twisting type and is more particularly concerned with the mechanical interconnection between the record-engaging stylus and the free end of the crystal element whereby the mechanical undulations of the record groove are transmitted to the crystal element for the generation of the amplitude modulated frequencies necessary for the electrical transcription of sound.

In certain applications it is desirable that the mechanical member or chuck used to drive the crystal element be provided with means to receive a pair of stylii either for fuctioning with records having different styles of grooves or for playing either the top or bottom side of a horizontally disposed revolving record and I have illustrated my invention as being applied to a pickup cartridge of this nature although it should be understood that the principles of the invention are equally applicable to a cartridge employing but a single stylus.

The two casing sections 16 and 11 are each provided with aligned top and bottom semicircular recesses which upon assembly of the sections may receive and clamp a pair of vertically spaced but aligned sleeves i3 and 14 formed of a suitable compressible material such as soft rubber; Received in the sleeves 13 and 14 are the top and bottom end portions of the shanks of my improved stylus holders and driving chucks and it will be understood that the sleeves 13 and 14 will be sutliciently compressed between these shanks and the casing sections 16 and 11 that a suitable degree of damping action is eifected for proper operation of the pickup cartridge. In either embodiment of the invention illustrated the advantages of simplicity of construction, strength, and short coupling between the stylus shank and the crystal element are attained.

Referring first to the embodiment of the invention illustrated in Figures 1, 2, 5, 7 and 8 it will be noted that the improved stylus holder and coupling member of my invention is formed of a single piece of sheet metal having a vertically disposed hollow shank 15, the vertical opening through which is non-circular in cross section due to the presence of the flat side 15a. This shank is split in the center of the curved wall opposite the flat portion. 15a and extending integrally out from these adjacent edges of the sheet is a pair of spaced parallel ears 16 each of which integrally supports a C-shaped clamp member 17. The gauge and temper of the sheet metal used in the fabrication of this assembly is such that the piece is sufliciently rigid upon forming so that no further processing or securing of the piece is required. 1

In using the chuck member described above it will be noted from Figures 1 and 2 that the shank 15 is vertically disposed and has its upper and lower end portions received in the sleeves 13 and 14. The cars 16 and clamp member 17 extend rearwardly to position the clamp member 17 on opposite sides of the adjacent free end of the crystal element 12 and in accordance with usual practice a pad 18 of relatively firm but yet compliant material such as soft rubber is interposed between the clamp 17 and the side surfaces of the crystal element 12. It will be understood that the inherent resiliency of the clamp 17 is suflicient to clamp and retain the pad 13 in assembled position although, if desired, the pad may be lightly cemented on to the crystal element.

The record-engaging stylii intended to be used with the improved chuck of my invention may comprise a mounting shank 19 which is non-circular in cross section complementary to the internal shape of the shank 15 and which is dimensioned to be tightly received in the shank 15. The inherent springy nature of the shank 15 will retain the shank 19 of the stylus in proper operative position while yet enabling the stylus to be readily withdrawn and inserted in the shank without the use of tools. Rigidly connected to the stylus shank 19 is a forwardly and downwardly extending piece of compliant wire 20 which carries at its forward end a downwardly turned portion 21 mounting a record engaging tip 22.

It should be observed particularly that the construction of the chuck 1517 and the manner in which it is mounted in the cartridge casing provides a relatively firm axis for the required rocking movement of the chuck but, nevertheless, provides for an elastic vertical movement of the stylus and chuck assembly to thereby reduce noise and guard against breakage of parts.

In the embodiment of the invention shown in Figures 3, 4, 6, 9 and the shank or barrel portion 15, a of the stylus is identical with that of the first described stylus but a modification is made in the construction of radially disposed driving projection. Thus, ears 16' which correspond in general with the cars 16 of the first described embodiment are notched out in their outer edges as shown at 16" in Figure 6 and, of course, the clamp member 17 of the first embodiment is eliminated. A driving chuck of this character may be utilized as shown in Figures 3 and 4 wherein a formed sheet metal clip 23 is rigidly secured to the outer free end of the crystal transducer 25 and wherein the clip 23 is formed with a vertically disposed bayonet slot 26 into which the ears 16 can project. A rubber pad 27 is folded about the ears 16 and retained in the notches 16" to cushion the interengagement of the driving chuck and the clip 23. It should be observed that the arrangement of Figures 3 and 4 provides a shorter moment arm on the driving chuck for actuating the crystal so that the crystal is bent a lesser extent but with greater applied force than is the crystal in Figures 1 and 2. This may be necessary or desirable in some applications and accordingly my invention is quite useful in providing for this variation in design.

In either of the embodiments described above rocking movement of the chuck about its principal axis, as results from lateral movement of the tip ends of the record-engaging stylii, is faithfully transmitted to the crystal transducer because of the short direct coupling provided by the ears 16, 16 and therefore the pick-up assembly may have good fidelity of response. Since the chuck is made of spring metal and has a normal free-standing opening of slightly less dimension than the shanks 19 of the stylii the latter will be firmly gripped in the chuck to faithfully transmit thereto the mechanical undulations of the record groove. Of course, the noncircular cross section of the chuck socket and the stylus shank contributes to this result while automatically providing a means to longitudinally align the stylus. Because of the substantial spacing of the bearing points 13 and 14 distortion of either will not appreciably alter the axis of the chuck or change the spacing of this axis with respect to the crystal so that the assembly continues its faithful reproduction of the recorded sound while needle scratch and other surface noise is being dissipated in vertical vibrational movement of the chuck as permitted by the flexibility of the grommets 13 and 14. Severe vertical blows applied to the chuck as by accidentally dropping the pickup head for example are also effectively resisted by these grommets and it should also be observed that in such case clamp 17 or the cars 16' can have vertical sliding movement with respect to the crystals so that there is no danger of injuring the latter or impairing the operative driving connection between the chucks and crystals.

Either of the above described embodiments of the chuck of my invention may be produced almost entirely by automatic stamping utilizing a progressive die from a continuous strip of stock as shown at 29 in Figures 7 through 10. The various stages of the dies are as indicated on these figures and it should be particularly observed that to change from the chuck of Figure 5 to the chuck of Figure 6 it is only necessary to insert in the die set a second blanking punch which is outlined at 30 in Figure 9 to trim away the stock which in the embodiment of Figure 5 makes up the clamp 17 and the straight outer edges of the cars 16. 0 course, the clamp-forming dies remain in the set but since the stock is eliminated they simply idle through their cycle.

It should now be apparent that I have provided improved stylus-holding chucks for phonograph pick-up cartridges and improved methods of making the same which accomplishes the objects initially set out above. The improved chuck itself has superior characteristics as regards ease of installation, fidelity of response, ease of mounting and replacing stylii, noise suppression, and durability but the invention further enables the chuck to be economically produced in an automatic manner from continuous strip stock and by the use of standardized die-forming apparatus which may be most elementarily altered to change the final form of the chuck to best suit different applications.

The above specifically described embodiments of the invention should be considered as illustrative only as many changes may be made therein without departing from the spirit or scope of the invention. Reference should therefore be had to the appended claims in determining the scope of the invention.

I claim:

A phonograph pick-up cartridge assembly comprising a longitudinally extending housing and a longitudinally extending transducer element therein, said housing being formed with a vertically spaced pair of apertures offset horizontally and forwardly with respect to said transducer, a stylus-holding chuck having oppositely extending stylus-receiving portions journaled in said vertically spaced apertures, and means providing a driving engagement between said chuck and said transducer element including a resilient folded pad; the improvement in said stylus holding chuck characterized by said chuck comprising a single piece of sheet metal and having a vertically disposed barrel portion defining stylus-receiving portions at each end thereof and comprising the central portion of said piece of sheet metal, said stylus-receiving portions being of non-circular cross section and adapted to receive a pair of record-engaging stylii having correspondingly non-circular shanks in the ends of said vertically disposed barrel, said stylii extending generally parallel with but forwardly of said transducer element, said stylus-receiving portions having a vertical split along the side thereof facing rearwardly toward said transducer element, tabs secured to and projecting radially outward from the side wall of said barrel portion intermediate the ends thereof on opposite sides of said split to provide a driving connection with said transducer, said resilient pad being interposed between said tabs and said transducer element, and said tabs comprising opposite edge portions of said piece of sheet metal.

References Cited in the file of this patent UNITED STATES PATENTS Begun Nov. 28, 1944 10 6 Andrews Aug. 23, 1949 Jafie Oct. 18, 1949 Bauer July 4, 1950 Weil May 15, 1951 Munroe Jan. 1, 1952 Chorpening July 1, 1952 Jensen Dec. 8, 1953 Bauer Feb. 2, 1954

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