US2962290A

US2962290A - Phonograph pick-up

Info

Publication number: US2962290A
Application number: US614156A
Authority: US
Inventors: Jr Lee Gunter; Carl R Anderson
Original assignee: Shure Brothers Inc
Current assignee: Shure Inc
Priority date: 1956-10-05
Filing date: 1956-10-05
Publication date: 1960-11-29
Anticipated expiration: 1977-11-29

Description

Nov. 29, 1960 Gum-ER, JR; ETAL 90 PHONOGRAPH PICK-UP 3 Sheets-Sheet 1 2 1 612 015".- .Zee Guzzzej; (Z1: n Carl fig) Qua 6229012 2y- Filed Oct. 5. 195

Nov. 29, 1960 L. GUNTER, JR.. ETAL 2,962,290

PHONOGRAPH PICK-11? Filed Oct. 5, 1956 3 Sheets-Sheet 2 72 U; fi e zfiars: lee 614222 623171. and Carl figar Giza/6119012 dig 1960 L. GUNTER, JR.. ETAL 2,962,290

PHONOGRAPH PICK-UP Filed oct. 5, 1956 3 Sheets-Sheet 3 lee Gazzzf'ezj Jr." a

fi/ezziors: I

6221'! I376? dyzciens'ozz I A!!! I M 02% PHONOGH PICK-UP Lee Gunter, Jr., Mount Prospect, and Carl'R. Anderson, Chicago, Ill., assignors to Share Brothers, Incorporated, Evanston, 111., a corporation of Illinois Filed Oct. 5, 1956, Ser. No. 614,156

16 Claims. (Cl. 274-37) This invention is concerned with a phonograph pick-up adapted to be mounted at the free end of the pivotal tone arm of a phonograph. The invention is more particularly concerned with a pick-up cartridge of the type having one needle releasably retained within the pick-up;

Phonograph pick ups of the single needle type have been known heretofore and these have conventionally been so constructed that the needle is replaceable by means of loosening some screws or the like. Such a construction has the disadvantage of being cumbersome for the operator in making needle changes. In addition, where such screw mountings are dispensed with, it becomes necessary that the needle mounting means provide for a firm retention of the needle in the cartridge while allowing for ready assembly and disassembly and proper positioning of the needle.

It is an object of the invention to provide a pick-up cartridge in which a single needle is arranged for playing laterally modulated records. Another object of the invention is to provide a pick-up cartridge which exhibits a high degree of fidelity and voltage sensitivity in reproducing recordings, and wherein the effective mass of the moving system is extremely low. A further object of the present invention is to provide a single needle pick-up cartridgeand needle assembly wherein the needle is readily replaceable and in which the new'needle is guided into position without disturbing the pick-up mechanism and is always positioned correctly in the pick-up. A still further object is to provide a phonograph single needle pick-up structure which is simple and economical in meohanical design and readily lends itself to rapid machine production. Another object is to provide anovel needle assembly which makes possible the attainment of these objectives.

Further objects and advantages of the invention will become readily apparent upon a reading of the description which follows hereinafter and upon an examination of the drawings, in which:

Fig. 1 is a side elevational view, partly in section, showing the arrangement of a pick-up cartridge in a phonograph tone arm, in accordance with the present invention;

Fig. 2 is a bottom view of the pick-up cartridge shown in Fig. 1;

Fig. 3 is a front view'of the pick-up cartridge of Fig. 2;

Fig. 4 is a cross sectional view through a spring stilfener element;

Fig. 5 is a sectional view, taken along line 55 of Fig. 3

Fig. 6 is a side elevational view of the needle assembly of the invention;

Fig. 7 is a top view of the needle assembly;

Fig. 8 is a front view of the needle assembly;

Fig. 9 is a view in perspective of the damping block for the needle assembly;

Fig. 10 is a fragmental side view, showing the piezoelectric transducer and the associated coupling member;

Fig. 11 is a front view of the coupling member shown in Fig. 10;

2,962,296 Fatented Nov. 29,1960

Fig. 12 is a bottom view of the transducer element;

Fig. 13 is a cross sectional view taken along line 13--13 of Fig. 10;

Fig. 14 is a top view of the electrical terminal member of the pick-up; and V Fig. 15 is a side view of the electrical terminal member shown in Fig. 14.

As shown in Fig. 1, the pick-up cartridge 1 is mounted within a hollow tone arm 2, at the free end portion thereof. The hollow tone arm is pivotally attached to the phonograph (not shown) at its other end, in the usual manner. The pick-up 1 is composed of two

casing sections

18 and 20 of suitable insulating material such as synthetic resin, said sections having complementary cavities forming a'suitable interior cavity 4 (see Fig. 5) for the parts to be contained therein. The casing sections are fastened together by rivets or

elongated eyelets

6 and 8 which also may serve as the means for fastening to the phonograph tone arm, i.e. screws or rivets may be passed through the

eyelets

6 and 8 and afiixed to the phonograph arm. A pair of

electrical terminals

10, 10 extend from the rear of the pick-up. 1 and are connected to a pair of conductors 12 and lead Wires 14 which in turn are connected in the usual manner to the amplifier system of the phonograph.

The casing sections are assembled by means of the eyelets as above described. However, a pair of

spring stifiieners

16, 16 are clamped against the sides. of the pick-up by the rear eyelet 8- in order to prevent the casing from being spread apart by the force of the transducer element mounting blocks contained therewith. The

casing sections

18 and 20 are so constructed that when they are assembled together, a socket 22 is produced into which the needle spade assembly may be directly inserted (see Fig. 5

Asv indicated in Fig. 5, the socket 22 is formed as a result of the overlapping of a protrusion 24 on the case section 18 and a protrusion 26 on the other casing section 20. When the casing sections are assembled together, the elongated socket 22 is formed between the

protrusions

24 and 26. This formation of a needle socket insures that top and bottom surfaces of the socket will always be in planes perpendicular to the casing halves and therefore normal manufacturing tolerances will tend only to narrow or widen. the socket without tilting the needle assembly. An alternative means of providing a socket for the needle would be to form a carefully controlled and mating slot in each case half.

A piezoelectric transducer element 30, which is in the general form of an elongated bar, is mounted substantially fixedly at its rearward end portion adjacent to the rearward end of the cavity 4 within the pick-up 1, and extends diagonally downward and forward. The element St) is clamped between two blocks 42 of an elastomeric material such as natural or synthetic rubber, said element 30 and blocks 42 being compressed between the side Walls of the cavity 4. As is shown in Fig. 12, the transducer element 30 is composed of two plates 32, 34 of piezoelectric substance, which may be of a ceramic composition such as two plates of barium titanate. The two plates 32, 34 are separated by a shim 36, which may be of brass. On the outer surfaces of the two plates are placed electrodes 38, 49 which may be of silver. As shown in Figs. 14 and 15, the tab 44 of the terminal member 10 extends upwardly and then curves around and extends rearwardly and joins the main portion of the terminal which extends through the wall of the pick-up casing. As shown in Fig. 5, the tab 44is compressed between block 42 and the side of transducer element 30, furnishing electrical contact between the electrodes of transducer element 30 and the terminals 10, 10'. A single opening is provided for both

terminals

10, 10 in the rearward wall of the pick-up casing, and a block 46 of elastomeric insulating material is compressed into said opening and between the terminals. The blocks 42 provide a semi-rigid mounting for the rearward end of the transducer element 30 whereby lateral vibratory motion of the free forward end of said element under the influence of the needle, causes a bending action of the element with resulting generation of electrical impulses, as is well understood. Said impulses are transmitted to terminals 10, conductors 12 and 14 and the electrical-acoustical system of the phonograph and result in the reproduction of sound from a recording.

At an intermediate portion of the transducer element 30, a damping block 48 is arranged on each side of the element and is under compression between the element and the side wall of the cavity 4. Such damping blocks 48 are composed of a suitable damping material, such as synthetic rubber. At the forward end of the transducer element (see Fig. 13) there is a protective covering 50 of insulating sheet material, such as paper, which is folded about and adhesively joined, as by cement, to the end portion of the transducer element.

A coupling member 52 for transmitting mechanical vibrations from the needle to the transducer element 30, is connected in motion-transmitting relationship to the free end of said transducer element. The coupling member 52 is in the form of an elongated arm which is U-shaped in transverse section (see Fig. 13) throughout the major portion of its length. The coupling member may conveniently be made of copper plated cold rolled steel. At the upper end of member 52, the legs of the U are pressed together to form a flattened or blade section 54. (See Fig. 11.) This blade section is inserted cantilever-fashion in a slot in the supporting and fulcrum block 56, which is in turn affixed into a recess 4a in the upper portion of the cavity 4 (Fig. 5). The fulcrum block 56, being aflixed at its upper surface to the casing provides a support for the coupler in addition to the support contributed by the transducer 30. Said fulcrum block is composed of an elastomeric material, such as natural or synthetic rubber, and the coupling member 52 is aflixed in the recess of said block by suitable attachment means such as rubber cement. The coupling member 52 extends downwardly from the block 56 and the free end of the transducer element 30 is received in the channel of the coupling member and is attached thereto, as by cement. The point of attachment of the transducer element to the coupling member is advantageously made roughly two-thirds of the length of the coupling member away from the point of attachment to the block 56. The coupling member 52 extends downwardly beyond the juncture with the transducer element 30 and the distal or free end portion thereof has a generally V-shaped notch therein, as shown at 58 (Fig. 11), for engagement with the needle 60 when in operative position. In operation, the needle 60 undergoes lateral vibrations in following the record groove, and the coupling member 52 acts as a lever, fulcrumed upon block 56, in transmitting the vibrations to the free end of the transducer element 30.

As shown in Figs. 6-9, the needle assembly 62 is made up of three parts; viz, the needle spade structure 64, needle 60, and damping material 66. The rear portion 68 of the needle spade 64 is a tongue, so formed as to slide snugly into the socket formed by the casing sections. This tongue is bent to form a leaf spring which bears resiliently against the top rear end and bottom middle of socket 22 (Fig. 5) when the needle assembly is installed in the cartridge. Alternatively, the spring tongue may be made straight, and the socket shaped to provide the bearing relationship noted above, the important consideration being that the needle end of the assembly is biased upwardly for purposes hereinafter explained. Two wing portions 74) and 72 (Fig. 7) extend laterally from the main spade structure. These portions project beyond the sides of the cartridge casing and serve as finger grips to grasp the needle when inserting or removing it. By means of these wings and cooperating pick-up casing structure, the forward part of the needle assembly is kept clear of the coupler 52 as the needle is inserted or removed from the socket. The edges (Fig. 1) formed in the casing halves have a curved portion which cooperates with the curved portion 82 of the needle spade 62 to provide a slide therefor, so that when inserting the needle, the curved portion 82 of the needle spade rides on the curved portion 80 of the casing. When removing the needle, as for replacement purposes, this curved portion 82 depresses the forward portion of the needle out of engagement with the coupler 52 and prevents dragging the needle assembly across the end of the coupler. When the tongue 68 has been completely inserted into the socket 22 (Fig. 5), needle 60 is allowed to seat resiliently in the notch of the coupler, due to the spring action of the tongue, to assure good coupling between these elements of the vibrating system.

The

wings

70 and 72 also serve as detent means to provide a positive positioning of the needle assembly 62 in the cartridge casing. This positive positioning is accomplished by edges 76 and '78 of the

wings

70 and 72, respectively, seating against the casing structure edges 80 at the mouth of the socket 22 (see Fig. 1).

The forward portion 74 of the needle assembly 62 has the two

side flanges

84 and 86 bent upwardly to form a cup which encloses the damping material 66 about the needle 60. These flanges also serve to locate the needle assembly with respect to the sidewise positioning within the casing. The casing sections have recesses 88 and 90 (see Fig. 2) to accommodate the

side flanges

84 and 86 of the needle spade. The curved portions 92, on each of the

side flanges

84 and 86, serve as an additional safety feature in removing the needle. Thus, when the needle is removed, this curved portion 92 cooperates with the edge portion 94 (see Fig. 5) on each casing section to lift the needle assembly out of engagement with the coupler, thus preventing damage to the damping material by the coupler.

The needle 60 is made of a wire shank which is flattened at its rear, as at 96, in order to be flexible in the horizontal direction of movement of the needle and yet relatively stiff in the vertical direction. A sapphire or other commonly used needle tip 98 is set in a hole at the end of the needle shank, or, if desired, the needle shank 60 may have an integrally formed precious metal tip. The flattened portion 96 of the needle passes through a slot 97 in the needle spade and is rigidly connected to the needle spade by means of solder 100 or equivalent means.

The damping material 66 is supported in the cavity formed by the

walls

84, 86 of the needle spade forward portion 74. Thus, a substantial part, if not all, of the flattened portion 96 of the needle is embedded in the damping material. The damping material 66 may be preformed as a block with a slot 102 extending the full length thereof to receive the needle shank 60 and cemented in place in the spade structure. Alternatively, the damping body may be formed in situ by pouring the material while fluid into the cavity and thereafter curing or permitting it to set. The damping material may be made of any of the commonly known plastic materials which exhibit suitable mechanical damping properties.

It should be noted, with reference to the relative positions of the transducer element 30, the coupling member, and the needle, that their respective functions and mutual relationships require only that the needle be arranged, preferably generally horizontally, to permit proper playing of a record, and the coupling be arranged, preferably, generally vertically, or, at least, at an angle to the needle, while the transducer element is arranged at any convenient angle with its free end fixedly coupled to the coupling element. The point of attachment of the ceramic element, and the length of the needle may be varied to change the lever ratio of the drive system, and thus modify the mechanical and electrical characteristics for a particular requirement.

The pick-up cartridge described above provides a novel needle assembly and simplified means for readily replacing the needle without the use of screws, etc. The detent action of the needle assembly is such that a positive location and positioning of the needle is provided at all times. In addition, the damping means for the needle shank insures that only the mass of the forward portion of the needle contributes to the mass of the moving system which is in motion-transmitting relationship with the coupling member 52.

We claim:

1. In a phonograph pick-up cartridge including a casing and a transducer element arranged therein, a fulcrum block of elastomeric material affixed in said casing for supporting a coupling member, a coupling member comprising a substantially rigid lever arm mounted cantileverfashion at one end thereof in said block for vibration of said arm about said one end thereof, said casing having an elongated socket opening forwardly at the bottom of said casing, a needle assembly including a needle extending forwardly therefrom and engaging the distal end of said coupling member lever arm and a leaf spring tongue extending rearwardly from said needle assembly into said socket with resilient frictional engagement of the surfaces thereof and urging said needle into resilient coupling engagement with said coupling member, said coupling member lever arm engaging said transducer element for driving the same in vibration responsive to vibration of said needle.

2. The cartridge structure of claim 1 wherein the elongated socket is oriented generally horizontally within the casing.

3. The cartridge structure of claim 1 wherein the casing comprises complementary side sections and the top and bottom surfaces respectively of the socket are formed by spaced overlapping protrusions of the respective casing sections.

4. The cartridge structure of claim 1 and including cooperating means on the needle assembly and on the casing for guiding said assembly into its proper position in the cartridge as said assembly is being moved into the socket.

5. The cartridge structure of claim 4 and including detent means on the casing for maintaining said assembly in proper position in the cartridge.

6. The cartridge structure of claim 5 and including detent means on the needle assembly and cooperating seat means on the casing for maintaining said assembly in proper position in the cartridge.

7. The cartridge structure of claim 1 wherein the needle assembly is provided with wing elements extending laterally from opposite sides of said assembly and projecting beyond the sides of the cartridge for grasping in assembling and disassembling the needle assembly in the cartridge.

8. A needle assembly for use with a phonograph pick-up cartridge comprising an elongated needle spade, a body of vibration damping material supported upon the forward portion of said spade in fixed relation thereto, a needle mounted lengthwise in said spade having its rear- Ward end rigidly connected to said spade and having its forward end extending beyond the forward edge of said spade, the shank of said needle passing through and engaging said damping material and arranged so that a portion of said needle is permitted to vibrate laterally with respect to said spade and alternately to compress and to permit to relax said block of damping material, and a leaf spring tongue integral with said spade extending rearwardly therefrom for supporting said needle assembly in said cartridge.

9. A needle assembly in accordance with claim 8 and including wing elements extending laterally from opposite sides of the needle spade for handling the needle assembly.

10. A needle assembly in accordance with claim 1 wherein the damping material engages the shank of the needle with the intimacy of contact which results from forming the body of damping material in situ from a fluid which sets to form said body.

11. A needle assembly in accordance with claim 1 and including side flanges integral with the forward portion of the spade for lateral support of the body of damping material.

12. A needle assembly for use with a phonograph pick-up cartridge comprising an elongated needle spade having a leaf spring portion, an intermediate inclined portion and a forward portion, a body of vibration damping material supported upon the forward portion of said spade in fixed relation thereto, a needle rigidly mounted cantilever-fashion in said inclined portion of said spade and extending over the forward portion and beyond the forward end thereof, the shank of said needle passing through and engaging said damping material and arranged so that a portion of said needle is permitted to vibrate laterally with respect to said spade and alternately to compress and to permit to relax said block of damping material.

13. A needle assembly in accordance with claim 12 and including wing elements extending laterally from opposite sides of the spade at the inclined intermediate portion thereof for handling said needle assembly and for guiding said assembly into position as it is inserted into a cartridge or removed therefrom.

14. A needle assembly in accordance with claim 12 wherein the portion of the needle at the mounted end thereof is flattened to render this portion compliant horizontally and stiif vertically.

15. A needle assembly in accordance with claim 12 and including side flanges integral with the forward portion of the spade for lateral support of the body of damping material.

16. A needle assembly in accordance with claim 15 wherein the forward portions of the side flanges are curved to provide cam surfaces for guiding the assembly as it is being inserted into or removed from a cartridge.

References Cited in the file of this patent UNITED STATES PATENTS 2,510,342 Kilgour June 6, 1950 2,689,734 Wennerbo Sept. 21, 1954 2,711,322 Dally June 21, 1955 2,717,929 Klingener Sept. 13, 1955 2,742,295 Frederick Apr. 17, 1956 2,752,428 Bauer June 26, 1956