US2931658A - Dual needle phonograph cartridge - Google Patents

Description

April 5, 1960 Filed March 17, 1954 J. F. WOOD DUAL NEEDLE PHONOGRAPH CARTRIDGE 3 Sheets-Sheet, 1

April 5, 1960 J. F. 'WOOD 2,931,658

DUAL NEEDLE PHONOGRAPH CARTRIDGE Filed March 17, 1954 5 Sheets-Sheet 2 j aw 00a! $2 a.-

April 5, 1960 J. F. WOOD DUAL NEEDLE PHONOGRAPH CARTRIDGE 3 Sheets-Sheet 3 Filed March 17, 1954 mill stylus.

United States Patent 2,931,658 DUAL NEEDLE PHONOGRAPH CARTRIDGE John Frederick Wood, Buchanan, Mich, assignor to Electra-Voice, Incorporated, Buchanan, Mich.

Application March 17, 1954, Serial No. 416,756

W Claims. (Cl. 274-36) In general, two types of phonograph records are now in common use, the one type having a three mil groove and operating at a speed of 78 r.p.m., the other type having a one mil groove and-operating at speeds of 33 /3. r.p.m. or 45 r.p.m. The use of such records has necessitated providing phonograph cartridges capable of playing both types of records. Various solutions have been offered. One solution is a compromised tip which is designed to ride on the upper edges of the groove walls of a one mil record. While this obviates the necessity of changing cartridges, or turning over cartridges, it has the disadvantage of greatly increasing the noise-pickup from the record, particularly above 5000 cycles per second. The compromise needle furthermore introduces tracking problems requiring excessive vertical force on the arm for acceptable operation.

Another solution to playing two types ,of phonograph records is a rotating mechanism where one side carries a one mil stylus and the other side carries a three mil stylus. Inasmuch as the amplitudes of the slow and high speed records are quite different, a considerable degree of compromise is required to provide a similar output voltage and frequency response from both styli.

posed to providea simple'andinexpensive practical solution .to the problems heretofore encountered in the turn- .overcartridgesor in the compromise stylus cartridge.

In the present instance, a cartridge is designed primarily for operation as a single needle cartridge to produce the desired amplitude output for the one mil groove phonograph records. In order to reproduce 78 r.p.m. or three -mil groove records, an additional stylus is provided which normally is inoperative, but may be moved into operative position to drive the cartridge through the original one Such anarrangement produces a better response and improves the tracking on the higher amplitude standard three mil record. -Furthermore in accordance "with the present invention two different types of output responses can be obtained. Because of the higher surface noise and distortion existing in the standard three mil records, it is usually desirable to reduce the response 0f the phonograph cartridge to f40Q00l' 5000 cycles per secon .It is, therefore, an object of the present invention to gradually roll off above ice compromise or change in the output characteristic of the cartridge. 7 Still another object of the invention is to eliminate the disadvantages encountered heretofore by the turnover phonograph cartridge either from the standpoint of the user or from the standpoint of the output characteristic. Still another object of the invention is to provide means for a phonograph cartridge for playing the higher speed phonograph records which will introduce the proper volume level or frequency response compensation.

These and other objects of the invention subsequently will become apparent by reference to the following description taken in conjunction with the accompanying rawings, wherein:

Figure 1 is a side view of a phonograph cartridge embodying the present invention shown in operating position for low speed or microgroove phonograph records;

Figure 2 is a side view of a phonograph cartridge of the present invention shown in position for playing the high speed conventional groove phonograph records;

Figure 3 is an enlarged view of Figure 1 with portions thereof broken away to show construction details;

Figure 4 is an enlarged view of Figure 2 with portions broken away to show certain details;

Figure 5 is a transverse cross-sectional view as seen in the direction of the arrows along the line 55 of Figure 3;

Figure 6 is a transverse cross-sectional view as seen in the direction of the arrows along the line 6-6 of Figure 3; Y

Figure 7 is an enlarged bottom cartridge;

Figure 8 is an exploded view of the cartridge and carriage; Figure 9 is a detailed cross-sectional view as seen in the direction of the arrows along the line 99 of Figure 3;

Figure 10 is a detailed cross-sectional view as seen in the direction of the arrows along the line 10-10 of Figure 4; and

- Figures 11 and 12 are plan views of a portion of the manual actuator for the carriage.

Reference now may be made to Figures 1 and 3 which show a phonograph cartridge having a casing 15 suitably supported from a tone arm 16 in operative position relative to a phonograph record 17 carried by a turntable 18. The cartridge casing 15 is provided on its sides with a pair of plates 15? suitably secured in position by aplurality of rivets 21. Each side plate has an apertured ear 22 which engagesa depending boss 23 of the tone arm 16. A suitable cap screw 24 passes through the apertured ear 22 to hold the cartridge in position. The side plates 19 also have a horizontal tab 25 whichserves as a guide for a carriage subsequently to be described. The side plates also have two horizontal guide portions view of the phonograph :26 at the lower edge thereof-which cooperate with the each have a longitudinal slot 29 which surrounds the tab 25 of the side plates 19. The relation'of the side members 27 and the tabs 25 is furthermore illustrated by the cross-sectional view of Figure 6, which at the same time clarifies the manner of supporting the cartridge and'the side plates 19 from the bosses 23 of the tone arm 16. a

illustrated in Figures 1 and 3. to the other operating condition as shown in Figures 2' jlje cartridg'e casing 15 adjacent to one end has an opening through which projects a chuck 31 which carries a one mil phonograph stylus 32 shown in engagement with aphonograph record. The slidable carriage having s'ide rncm bers 27 also has a generally fiat bottom portion 33,,which bearsagainst the edge portions 26 of the side pl The flat. poition 33 is split longitudinally ren ng curved portions 34, as seen in Figures 1, 3 and, 6 which depend from the flat portion 33. The rear gt'the curved portion 34 has a suitable aperture 35 th ugh which a resilient support member 36 extends and secured to the rearmost portion of the fiat portion 33 qflthe slide or carriage. The resilient member 36 constitutes a cantilever carrying at its outer end a chuck 31, which in turncarries a three mil stylus 38. Near the front end of the chuck there is secured a coupling member 39 having at its front end a V-shaped notch 41. From the position shown in Figures 1, 3 and 6, it is apparent that the stylus 38 does not inany way interfere w ith tlie operation of the one mil stylus 32. The carriage passes to the position shown by an over-center spring142 having an end 42A which passes through an aperturein the side'plate 19 and extends into a suitable recessflij in the casing 15 of the cartridge as shown in Figure 5. The other end of the over-center spring 42 passes througha suitable aperture in the side member ,27 of the movable carriage.

The movable carriage at its front end is provided with an actuator and indicator 45 having a finger grip 46. ,The actuator 45 is in the position shown in Figure 11 when slow speed records are to be played and indicates that .the phonograph cartridge .is arranged for playingthe slow speed records. When the actuator is moved to the position shown in Figure 12, the assembly is then ready .forreproduction of the higher speed three mil groove records. Reference now may be had to Figures 2 and 4 which show the carriage moved forwardly and retained in this position by the over-center spring. The opposite end g'fthe longitudinal slot 29 now engages the tab 25, thus accurately determining the new operating position of the carriage. In this position, the coupling member 39, which is of rigid construction, has its V-shaped groove 41 in engagement with the stylus 32 so that it has moved. it upwardly to 'a certain degree. 'At the same time, the engagement ofthe coupling member 39 with the stylus 32 has moved the other stylus 38 downwardly Iintoplaying position 'into engagementwith the phono- From the foregoing, it will be appreciated that there has been illustrated in the drawings an embodiment which is of relatively simple construcLion, and is convenient to operate by the user. This construction furthermore has the advantage of permitting the phonograph cartridge to have a relatively high fidelity output characteristic for the one mil or long playing records, and to provide the desired cut oifin frequency response for the older, noisier 78 r.p.m. records. The proper amplitudes of output are readily obtained without compromise.

The construction illustrated has another advantage in that the compliance of the three mil stylus also makes it possible to properly track the high amplitude grooves graph record. From Figure 4, it will be noted that' "the resilientsupport 36 has sufiicient compliance so that the two 'styli are coupled together in the proper manner with'out damageto each other. The combined mass and compliance as represented by the chuck 37, the stylus 38, and the coupling member 39 is such that the proper *a'mplitude motion is now'transmitted to the stylus 32. It'should be apparent that the amplitude of actuation of the stylus 32 is less than 'theamplitude of movement of the stylus 38. The mass and compliance can be so designed that the response characteristic of the phonogrjaph cartridge now differs from the higher fidelity response characteristic particularly designed for the reproduction of the one mil phonograph records. The relation of the parts is still further illustrated by Figure 7 which shows the bottom view with the slide in the rearmost position, leaving the stylus 32 in playing position. The

relation of the styli under different conditions is also illustrated by Figures'9 and 10 where Figure 9 shows the relat on ofthe V-sh'aped notch 41 of the coupling memof the high speed records with adequate vertical force. The arrangement is designed to have the proper vertical force for operation with the one mil stylus. Thus, the microgroove or slow speed records are not subjectedto excessive wear due to an unusually high vertical force which otherwise might be required in other types of construction.

While for the purpose of illustrating and describing the present invention a preferred embodiment has been shown in the drawings, it is to be understood that the inventionis not to be limited thereby since such other embodiments or variations are contemplated as may be commensurate with the spirit and scope of the invention set forth in the accompanying claims.

' I claim as my invention:

1. A phonograph reproducer comprising, in combina* tion, a phonograph pickup having a housing adapted to be mounted to a tone arm, an electromechanical transducer mounted within the housing, a first stylus, means for coupling the stylus to the transducer including an arm connected to the stylus, a second stylus, means for mount ingthe second stylus to the housing including a compliant member attached to the housing at one end and coupled to the stylus at the other end, said means normally disposing the second stylus between the first stylus and the transducer, and two position means to couple the second stylus to the transducer, said means moving the second stylus between a first position between the first stylus and the transducer and a second position on the opposite side of the first stylus relative to the transducer, said means including a rigid member at t'ached to the second stylus and means for translating the member between a first position in which 'the member is spaced from the first stylus and the arm and a second position in which the rigid member engages the arm attached to the first stylus and bends the compliant mem' ber to place the first stylus between the second stylus and thehou'sing. 1

a 2. A phonograph 'reproducer comprising, in combination, a phonograph pickup having a housing adapted to be mounted to atone arm and having a surface oriented with respect to the plane of the tone arm when so 'n-iounted, an electromechanical transducer mounted within the housing, a first stylus, and means for coupling the stylus to the transducer including a rod connected to the stylus and oriented with respect to the surface of the housing to provide an angle to the plane of the her 39 with respect to the 'stylus 32 under the conditions When the slide'is moved and 4, the relation of the two 'styli is illustrated by Figure 10 which shows the V-shaped notch 41 of the coupling member 39 in firm engagement with the shank of the stylus 32. t

tone arm, a carriage slidably mounted to the housing, means whereby said carriage is slidable on an axis oriented with respect to the surface of the housing to be parallel to the plane. of the tone arm and the plane of the rod normal to the plane of the tone arm, a second stylus, rneans for mounting the second stylus to the carriage including "a resilient member mounted to the car age atone end and a rod connected between the member and the second stylus and normally oriented with respect tothe surface of the housing to be parallel with the plane of the tone arm, and means including a lrig'id mernber secured to the mounting means between theresilient memberand the second stylus and having "a notch'atone end aligned with "the rod, whereby the.

3. A phonograph reproducer comprising the elements said first stylus in the other of said positions, and means of claim 2 in combination with an over-center latching spring attached to the carriage in the housing for re- 7 taining the carriage in either of the two positions;

4. A transducer comprising a support member, a transducing element mounted on said support member, a first stylus fixedly mounted on said support member and connected to said transducing element, a second stylus mounted on said support for movement between two stable positions, means whereby said second stylus is below said first stylus in one of said positions and above for mechanically coupling said second stylus to said first stylus only when said second stylus is in said one position.

References Cited in the file of this patent UNITED STATES PATENTS 1,228,901 Gibson June 5, 1917 1,420,316 Holland June 20, 1922 1,866,403 Elmer July 5, 1932 2,033,284 Harrison Mar. 10, 1936 2,533,359 Dann Dec. 12, 1950 2,545,652 Dann' Mar. 20, 1951 2,568,671 Vistain Sept. 17, 1951 2,572,495 La Forest Oct. 23, 1951

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