US2769038A - Phonograph pickup and the like - Google Patents

Description

Oct. 30, 1956 M. ORTON ETAL PHGNOGRAPH PICKUP AND THE LIKE 4 Sheets-Sheet 1 Filed Nov. 29, 1952 I N V EN TORS ME L VEfP/V 0/? TON J- SCHULTZ A T TORNF Y Oct. 30, 1956 M. ORTON ETAL 2,769,038

PHONOGRAPH PICKUP AND THE LIKE Filed NOV. 29, 1952 4 Sheets-Sheet 2 N JNVENTOR MELVER/V ORTON HENRY J, SCHULTZ BYBROO/(S WALKEZQAQK ATTORNEY MN; 9 lmllwuullmii m J.IT I I I I I I I l I I.) 1 1111 ll i H mm Q ||1| l||l1 r 1L \N I l l I l I I l l I!LTI| Oct. 30, 1956 M. ORTON ETAL PHONOGRAPH PICKUP AND THE LIKE 4 Sheets-Sheet 3 Filed Nov. 29, 1952 5 m NL m m 5 WWW M 05 m NJ T Z A VR m amm flwa B mm Nfl hMN United States Patent PHONOGRAPH PICKUP AND THE LIKE Melvern Orton, Alameda, Henry J. Schultz, Hayward, and Brooks Walker, Lafayette, Calif.

Application November 29, 1952, Serial No. 323,326 Claims. (Cl. 179-100.41)

This invention relates to an improved phonograph pickup and the like, of the type employing a fluid currentmodulating medium.

In the type of pickup to which this invention relates, the phonograph needle is mounted on an actuator member which is swung in a small are as the needle moves back and forth laterally in the record groove. The swinging of the actuator is used to modulate an electric current that flows between two or more electrodes through an electrolytic fluid contained in cavities or cells in a body member made of insulating material.

A preferred pickup construction divides the body member into three serially adjoining cavities, each containing an electrode and liquid. The central cavity is joined to the other cavities by a pair of orifices Whose areas are varied by the actuator member in response .to the movement of the needle. Each orifice may be formed between a wall of the chambers and a flexible diaphragm which yields to pressure exerted by the movement of the actuator member and tends to resume its shape when the pressure is relaxed by movement of the actuator member in the opposite direction. Each time the orifice changes in size, the electrical resistance between adjacent chambers changes, varying the current flow and voltage between them. In a pickup having three chambers, a difference in electric potential can be set up across the electrodes in the end chambers, and a varying voltage can be obtained from the electrode in the central chamber. This variation, obtained by varying the areas of the orifices between the central chamber and the other two chambers, causes the voltage on the electrode in the central chamber to increase and decrease relatively to the potential of the other two electrodes, although voltage between these two electrodes remains constant.

Those records adapted to rotate at approximately 33 R. P. M. or 45 R. P. M. have grooves that are substantially narrower than the grooves in the records which rotate at 78 R. P. M. For that reason, the needles. which were best calculated to give ideal results with the 78 R. P. M. records are too large to give ideal results with the 33 R. P. M. and 45 P. M. records. it is therefore desirable to have two different sizes of needles available so that any type of record can be played with its proper needle. It is also desirable in a phonograph pickup of the modulating fluidtype to be able to use a permanently mounted needle which has a life approximately coterminous with that of the pickup cartridge, because this makes it possible to do away with the inconvenience and added weight of the type of needle-holding chuck in which a screw is tightened on the needle.

Accordingly, the present invention is of the type providing an actuator that extends perpendicular to the plane of the record, as in the Harry C. Warner application, Serial Number 284,865, filed April 29, 1952. The diaphragm is mounted in a plane generally perpendicular to the plane of the record, and the structure contrasts With the type of structure where the actuator and diaphragm lay in a plane parallel to the record surface. Both ends of the actuator project out beyond the cartridge body, and this new structure makes it possible to have a needle on one end of the actuator adapted to play 78' R. P. M. records and another needle on the opposite end of the same actuator arm adapted for playing 33 R. P. M. and 45 R. P. M. records. Since the needles project from opposite sides of the pickup, the change from one type to another may be made simply by rotating the pickup cartridge through degrees. The change in needles does not affect the response characteristics of the cartridge, and its operation remains the same.

This same structure may also be used in automatic coin-operated phonographs of the type where the records remain in a series of vertical planes. The actuator and diaphragm will still be perpendicular to the record surface. In this type of phonograph, both needles will be the same, one being used to play from one side of the records and the other to play from the other side of the same records.

The vertical actuator (i. e., vertical with respect to the record) also minimizes needle scratch, because the actuator does not respond to the undesirable up-and-down movement of the needle, but only to the desired sidewise movement. This structure also makes it possible to use a very short actuator arm, a structural feature that simplifies the control of the amplitude-frequency responses of the pickup.

In addition to the above general features and advantages of the invention, several important problem have been solved herein. One of them has to do with elimination of the distortion that tends to occur when the actuator swings across too wide an arc. The present invention has solved this problem by providing a novel resilient control means for limiting the swing of the actuator within desired limits.

The present invention also solves a problem in connection with the mounting of the diaphragm. Previously, the diaphragm had to be cemented to the body member in order to get a tight enough seal and prevent leaks. The cementing operation not only took time and cost money; there was also the trouble that very small amounts of cement tended to get into the gaps or other critical places where it interfered severely with the proper performance of the device. The present invention makes it possible to hold the diaphragm in place without cement, and as a result the pickups can be made more uniform and more consistently accurate.

This invention also solves a problem caused by the lack of compressibility of the liquid current-modulating medium. When the diaphragm was placed under tension (as it always is during operation), the liquid would tend to deform the diaphragm. Even though this deformation might not be bad enough to rupture the diaphragm or the cement that sealed the diaphragm to the body, still the very deformation itself caused problems. Particularly when the portion of the diaphragm near the gap was affected, the performance would be distorted. This problem has been solved in the present invention by incorporating a deformable elastic tubular member inside one of the body cavities. This novel member absorbs the changes in fluid pressure by its own change in shape.

Further problems solved by this invention relate to the bearing structure for the actuator, the proper positioning of the parts, and to placing the desired pressure and control on these parts.

Other objects and advantages of the invention will appear from the following description of a structure embodying its principles. Sufiicient description is made, in compliance with the statute, to set forth the features of my invention, but not to limit the invention except as defined in the appended claims.

In the drawings:

Fig. l is an enlarged isometric View of an assembled pickup cartridge embodying the principles of the invention.

Fig. 2 is a further enlarged exploded isometric view of the pickup cartridge of Fig. 1, showing the various parts used in its assembly.

Fig. 3 is a still further enlarged view of the actuator member or armature, with the needles in place.

'Fig. 4 is a bottom plan view looking up from below at the cartridge, assembled in a bracket that is secured to the tone arm, the rear end of thertone arm being broken ofi to conserve space.

Fig. 5 is a view in side elevation and partly in section taken along the line 5-5 in Fig. 4, with the upper part of. the bracket and of the tone arm broken off to conserve space.

. Fig. 6 is a view in elevation and in section taken along the line 6-6 in Fig. 1.

Fig. 7 is a fragmentary enlarged view in section taken along the line 77 in Fig. 8, showing a portion of the device in the vicinity of the diaphragm.

Fig. 8 is a fragmentary view in section taken along the line 88 in Fig. 7.

Fig: 9' is an enlarged fragmentary view in section of a portion of a modified form of the device.

Fig. 10 is a view in perspective of the cartridge shown installed invertably in a novel turnover bracket.

Fig. 11 is aview in elevation and in section taken along the-line 11-11 in Fig. 10.

Brief over-all description nected to a source of electrical potential, electric current flows between them by way of troughs or gaps I and K in the outer edge of the partitions between the adjacent chambers B, C, and D. The sizes of the orifices at J and Kare controlled by a vertical armature or actuator" L whose pressure arms or levers normally hold the diaphragm'F under pressure in the vicinity of the gaps. At each'outer end of the actuator L is a chuck M, M which holds a stylus or needle N, N. As either needle N or N is moved from side to side by the record groove, the

actuator L rotates through a small arc, causing its pres 1 sure arms to push the diaphragm'F inwardly over one trough I while releasing somewhat the pressure over the other trough K. When the orifice at J is made smaller,

the-electrical resistance between the electrodes G and H is increased, and the increase in size of the orifice at K simultaneously decreases the resistance between the electrodes H and I. When the orifice K is made smaller, the.

reverse situation occurs between the electrodes. Thus the signal made'by the pattern inthe record groove is reproduced electrically and may be amplified and played over'a loud speaker.

The cartridge body When fully assembled, the cartridge ii)- may: appear as shown in Fig. l. The body member A, which contains or supports all the working parts, is complemented-by a cap '11 that protects these working parts and prevents tampering. Preferably the body A and cap 11' are selater. The bracket 15 may be provided with holes 16 through which bolts (not shown) may pass to secure it in a phonograph tone arm 17 (Figs. 4 and 5). Suitable mechanism (e. g., springs and stops or the spring-stop construction of the bracket 15, which will be described later) may be provided so that the cartridge 10 is retained at either one of two positions, 180 degrees apart, but not in any intermediate position. The needles N and N project out through openings 18 and 19 in the cap 11, and the needle to be used may be selected by turning the knob 13. Suitable identification of the needles may be printed or otherwise placed on the two horizontal surfaces of the knob 13. I

Both the body member A and the cap 11 are preferably made from a hard, rigid, strong plastic or some other strong material that is an electrical insulator. The body member A may be molded, if desired, in more than one piece and later assembled, the finished product being provided'with suitable openings, pivots, ledges, and so on, which will be described as the occasion arises.

In the form of the invention shown in Figs. 1-6 the body member A is provided with three liquid holding cavities or chambers B, C, and D which are preferably located symmetrically in the body A and are open only at their forward ends. The actual shape of these chambers is not critical (although the shapes shown have some advantages) so long as the center chamber C borders both chambers B and D. The center chamber C may be smaller than the outer chambers B and D because the electrode H in the center chamber C carries no direct current.

The body member A may be assembled from two separately molded portions 29 and 21 as shown in Fig. 2. In the larger rear portion 2%, the chambers B, C, and D are separated by the partitions 2'2 and 23. The electrodes G, H, and I maybe sealed in position in the portion 2% during the molding operation, the portions 24 that project outside the body A forming terminals. At its forward end, the portion 20 has a socket 25 adapted to receive the smaller body portion 21.

Thesmaller portion 21 of the body member may be separately molded or otherwise formed, and later cemented to the larger rear portion iii in the socket 25. Whefrso cemented, partitions 26, 27 of the portion 21 align with and become. integrated with the partitions 22, 23', and the walls also are aligned and integrated.

At the forward end of the body portion 21 an opening 36 extends across the chambers B, C, and D. instances it is convenient to have a relatively small opening Cid-so that a relatively small'diaphragm F may be used. In suchcases, the body portion 21 may be molded so that the chambers B, C, and D narrow down to the openings 30-, as-shown in Figs. 2 and 4.

The troughs or gaps J and K are at the forward end of. the partitions 26, 27 across the opening 36. They are preferably formed: with sharp edges 31, 32 and include a thousandths'of an inch deep and about fifty-five thoucured together permanently as' by cementing, but if desired they may he held removably, as by a snap fit. LA supporting front tip 12, which projects from. the front end of the cap 11 may be provided with a.turning knob .131, The cartridge is preferably supported? in'a turn-' oirerbracket bythe front tip 12 and a rear tip.14, the

bracket preferably but not necessarily being. like the bracket 15 shown in Figs. 10, ll, 4,.and5, andldescribed sandths of an inch wide, with a radius of about fifty thousandths of an inch, the. center of the are being located about forty-thousandths of an inch beyond the straight portion; of the. outer edge.

The pressure-compensating sack 4O Heretofore, normal temperature changes. during the yearhave causedtrouble by increasing theinternal pressure of the fluid in the cartridge. A novel feature of this cartridge is the incorporation therein; of a flexible, hollow tube or sa'ckltl which is closed at its inner end 41 and open at' its outer end 42. The tube 40, which is shown assomewhat flattened, may be made from neoprene or similar materialtthinner and more flexible than the diaphragm F) and may be located in any one of the three.

chambers, but is preferably located in the center chamber 0 where'there is more-excess'space. To accommodate the In many sack 40, the rear Wall 43 of the portion 20 may be formed with a stepped tubular opening 44 through which the tube 40 may be forced. The tube 40 is held in the outer wider-diameter portion 45 of the opening 44 by a hollow rigid bead 46 of plastic or glass, which also provides a communication between the interior of the tube 40 and the atmosphere. When a rise in temperature changes the pressure dilferential between the inside and outside of the cartridge and so increases the fluid pressure on the diaphragm F, that pressure will compress the tube 40 into a diiferent shape, instead of deforming the diaphragm F.

The positioning of the diaphragm F and actuator L Once the two portions 20, 21 of the body member A have been cemented together, the diaphragm F may be installed. Either before or after the installation of the diaphragm F, the cavities B, C, and D may be filled with the desired electrically conductive liquid E. (Filling afterwards may be done by a hypodermic needle.)

The diaphragm F may be cemented to the body A; however, it need not be cemented, so long as the assembly about to be described is used. If it is not cemented, it may be coated with a silicone grease (e. g., Dow-Cornings DC-4) to help insure a leakproof seal.

A rigid (preferably metal) bearing plate 50 slightly longer than the diaphragm F overlies it. The plate 50 has broad V-shaped bearings 51 that receive the sharp-edged, narrow V-shaped actuator bearings 52. A preferably rectangular opening 53 through the plate 50 so that the presser feet 54, 55 of the actuator L can touch the diaphragm F and preferably urge it in under pressure over the arcuate edges 33, 34. (See Figs. 7 and 8.)

Preferably the plate 50 is provided at each end with recesses 56 that are adapted to engage pins 57 which project out from the member 21. This helps achieve proper alignment of the plate 50 and the diaphragm F, and also helps the plate 50 support the enlarged heads M or M of the actuator L, to keep the actuator L aligned, without displacing the plate 50 or the diaphragm F.

In the form of the invention shown in Figs. 1-8, a rigid (e. g., metal) bearing block 60 is provided on the opposite side of the actuator L from the diaphragm F. The block 60 has wide V-shaped bearings 61 in which sharp V- shaped rear bearings 62 may rest. A rubber cushion block 63 yieldingly backs up the bearing block 60 and determines the pressure on it. This combination of the blocks 60 and 63 helps increase the effective mass of the actuator L and is not required when a heavy actuator L is used (cf. Fig. 9, which will be described later).

The diaphragm F, pressure plate 50, actuator L, and blocks 60 and 63 are retained in place by a U-shaped clip 65 whose sides have bent-in members 66 so that openings 67 are provided. The clip 65 is snapped over the body member 21, with the openings 67 providing access for ears 68 that are integral parts of the body member 21. The length of the parts, the compression of the block 63 and the springy pressure of the clip 65 hold the parts together without cement.

Preferably the clip 65 and bent-in members 66 are so positioned that the latter can press on the plate 50 and help hold it in place. Also other bent-in members 69 may be provided along the back of the clip for regulating the pressure on the cushion block 63.

The actuator L Fig. 3 shows that actuator L is symmetric. Two chucks M and M are provided, one on each end, to hold the needles N and N. The symmetrical construction means that the response will be the same whichever needle is used. This means, in turn, that no adjustment is necessary when changing from 78 R. P. M. records to 33 R. P. M. or 45 R. P. M. records, except to invert the cartridge.

6 The actuator L' and the cushion block 70 (Fig. 9)

The modification shown in Fig. 9 illustrates the use of an actuator L not needing any additional mass and so not requiring a bearing block 63. A cushion block 70 then directly engages the curved rear edge 71 of the actuator stem 72. The projecting rear portions 73, 74 of the member that also forms the presser feet 54, 55 almost touch the block 70. A very small swing of the actuator L' will cause the edges 73, 74 to touch the block 70, and further motion will bring about the application of a gradually-increasing braking force, or stop action, on the actuator L, thereby maintaining the swing of the actuator L and the range of opening of the gaps J and K within the proper limits.

Assembly of the cartridge To review the assembly of the cartridge 10: the body portion 20, including the electrodes G, H, and I, is secured to the body portion 21 to form the body member A. The cavities B, C, and D are filled with fluid E, and the diaphragm F is put over the opening 30, closing the body member A and sealing the fluid E inside. The pressure plate 50 fits over the diaphragm F, and the bearings 52 of the armature L fit in the bearings 51 of the plate 50, with the presser feet 54 and 55 fitting in the opening The turnover bracket 15 As stated earlier, the cartridge 10 is preferably supported invertably in the novel bracket 15, which is rigidly secured to the tone arm 17 by means of rivets or bolts (not shown) passing through the holes 16, or by other means. The bracket 15 may be stamped out from a single sheet of metal and bent to shape, by dies or otherwise. It has a central portion that extends over the cartridge 10 for substantially its full length, and there are depending arms 81 and 82 at the two ends. The length of the arms 81, 82, is sufi'icient to space the portion 80 away from the cartridge 10 enough to permit the cartridge 10 to be turned over without striking the portion 80. Sockets or journals 83, 84, are preferably provided to support the stems 12 and 14 rotatably.

It is very desirable to provide two limiting positions beyond which the cartridge cannot pass, and to provide means of snapping the cartridge 10 into its extreme positions, so that the needle N will be positioned exactly vertically. For this purpose the cartridge body cap 11 may be provided with a rectangular block stop 85 on one side of its front face, projecting out of a rectangular face portion 86. The bracket arm 81 is preferably offset, at 87, adjacent the socket, the dimensions of the offset 87, face 86, and stop 85 being adjusted to each other so that the lower edge of face 86 lies on the ofiset 87 when the cartridge is in either of its two extreme (e. g., operating) positions. The stop 85 at the same time engages with the edge 88 adjacent the offset 87, and prevents further rotation of the cartridge 10.

When the cartridge 10 is to be inverted, the handle 13 is turned. It will turn only in one direction-the direction depending on which edge 88 the stop 85 is then adjacent. When turned, the cartridge rotates, the stems 12 and 14 riding in the bearings 83, 84. The face 86, projecting beyond the remainder of the cap 11, engages the non-ofiset portion 89 of the arm 81 and pushes it forward, thereby causing an increase in the spring tension which normally is exerted through the bracket 15 to cause the outer ends of the arms 81 and 82 to be urged toward each other. When the cartridge 1t) is turned nearly 180, the face 86"willslide alon'g -the-ofiset 87, urged by the tension on the bracket arms, until it is snapped into its rest position with the stop 85 adjacent the edge 88,

Operation In the operation of'the device, the pickup cartridge is installed on a phonograph tone arm 17 in such an attitude that the actuator L will be substantially perpendicular' to the surface of the record to be played. When in use, the needle N or N (depending on which one is selected) moves from side to side in the lateraltype record groove. This side-to-side motion causes the actuator L to rotate over a very small arc on its pivots 51,52 and about its vertical axis. Rotation in one direction will cause'the presser'foot 54 to urge the diaphragm F in over the orifice], narrowing the orifice I. At the same time, the presser foot-55 permits the diaphragm F to relax over the orifice K, Widening the orifice K. The swinging'of the needle N or N in the opposite direction will cause the opposite action, so that the presser foot 55 would then'narrow the orifice-K and the presser foot 54 would permit'the orifice J to'widen. This action is always in balance with the result that the current passing from the electrode G to'the electrode I remains constant while the current at the electrode H is modulated. The tension on the diaphragm F is absorbed by somewhat collapsing the tube or sack 40.

The balanced operation helpsprevent needle scratch. The mounting of the actuator L so that it 'is perpendicular to the record surface and so that its movement is only rotational about the perpendicular axis, also prevents any up-and-down motion of the needle N or- N from being transferred to the diaphragm F, and thereby cuts out any effect except those due to the actual lateral movement of the needle in the record groove, which are the desired efiects.

The needle may be changed from N to N by inverting the cartridge 10 or by placing iton the opposite side of scription herein are purely illustrative and are not in-.

tended to be in any sense limiting.

What is claimed is: 1. A pickup cartridge for phonograph records includingin combination a first body'member of insulating material having a plurality. of cavities open at one end j and a socket at said end; a second body member of insulating material fitting in said socket and open at'both ends having a corresponding plurality of cavities extending therethrough, said cavities narrowing toward the outer end; a diaphragm cooperating with said second body member to define orifice means of variable size; an electrically-conductive fluid filling said. cavities; .electrodes in said cavities; and an actuator for fiexing'port'ions' of said diaphragm, thereby varying the size of said orifice i means 2.- 'An electric control device including in combination a body member having-an open-face with-a plurality of cavities recessed therein and isolated-from each other,. said body member havinglaterallyextendingfprojections on each side adjacent said open face; a diaphragm clos- U said cavities; a metal bearing plate overlying said diaphragm and urging it against said body, said bearing plate having a cutout central portion and broad V-shaped bearings on both sides of said central portion; an actuator member having laterally-extending members in contact with said diaphragm through said bearing plate cutout portion, for varying the size of said orifice means in response to external action impressed thereon, said actuator member having a stem provided with narrow V- shaped metal bearings resting in said bearing plate bearings; a clip for holding said parts together in contact and having openings for engaging said body members lateral projections; and a compressible pad between said clip and said actuator.

3. The device of claim 2 in which said clip openings are formed by bent-in tabs that engage said bearing plate and place tension thereon.

4. The device of claim 3 inwhich there are also bentout portions of said clip placing pressure onsaid pad.

5. Thedevice of claim 2 in which said body member is providedwith projections sticking up from said open face and saidbearing block isprovided With slots to re ceive said projections for obtaining alignment therewith.

6. The device of claim '2 in which said pad engages a smooth rear face of said actuator stem and substantially contacts. the rear of said laterally-extending actuator members, for controlling the amplitude of swing.

thereof with a gradually increasing braking action.

7. The device of claim 2 in which said actuator has 'a sharp-edged portion on the rear side of said stem and in which there is a bearing block with broad inclined bearings adapted to receive said sharp-edged portion, said bearing block lying between said actuator'and said pad.

8. A'pickup cartridge for phonograph records including incombination a first body member of insulating material having a plurality of cavities open at one end and a socket at said end; a second body member of insulating material fittingin said socket, open at both ends, having a corresponding plurality of cavities extending therethrough, said cavities narrowing toward the outer l end and having projections extending laterally outward;

a diaphragm cooperating with said second body member to define orifice means of variable size; an electricallyconductive fluid filling said cavities; electrodes in said cavities; metal bearing plate overlying said diaphragm and-urging-it against'said body, said bearing plate having'acut-out central portion and broad V-shaped bearings; an actuator member in contact with said diaphragm through'said bearing platecut-out portion, for varying the'size of said orifice means in response to external action impressed thereon, said actuatormember having narrow V-shaped' metal bearings'resting in said bearing open end sealed in said body so that its interior is open to the atmosphere outside said body.

10. An invertable two-needle, phonograph pickup cartridge, comprising a body member of insulating material having cavities joined by variable orifice means, said body member having axially projecting forward and rear stems, and also having a projecting front symmetric rectangular block" and stop member projecting'out beyond said blcclcon'one side thereof; an actuator member'for 'varyingthe size of said orificemeans, saidactu- I ator" extending linearly perpendicular to the surface of the phonograph record to be played, and each end of said actuator extending out of said body member; a stylus 2,769,038 9 18 secured at each extremity of said actuator; and a bracket References Cited in the file of this patent adapted to be rigidly secured to a phonograph tone arm, r said bracket having journals rotatably supporting said UNITED STATES PATENLS body member stems, a front edge that engages said stop 186,305 Bujac I an. 16, 1877 member when said actuator is positioned in either of 5 293,018 EdiSOn Apr. 30, 1878 its two operating positions, and an oflset portion that ,936, 37 Hubner Nov. 6, 1934 engages said block When said edge engages said stop 0 Olson Oct. 14, 1947 member, said bracket being forced outwardly by said ,57 ,712 Fisher Oct. 23, 1951 block when said block is not engaging said offset portion. ,6 8,726 Warner Aug. 11, 1953 10 2,671,153 Ray Mar. 2, 1954

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