US2313324A - Crystal pickup unit - Google Patents

Description

March 9, 1943. R. DALLY CRYSTAL PICK-UP UNIT Original Filed June 5, 1940 2 sheets-Shasta Q23 1/ I 28 g l' ,1 2 66 f A :4

Z W 27 ,flfg lg JIM Patented Mar. 9,

CRYSTAL PICKUP Um'r Roy Dally, Racine, Wis., assignor to Webster Electric Company,. Racine, Wis., a corporation of Delaware Original application June 3, 1940, I Serial No.

338,519, now Patent No. 2,261,616, dated Novemher 4, 1941. Divided and this be! 3, 1941, Serial No. 413,389

application Octo- 4 Claims. (Cl; its-100.41)

The present invention relates to pick-up units for tone arms andthe like, and is particularly concerned with improved pick-ups oi the crystal type.

This application is a division of my prior ap-- plication Serial No. 338,519, filed June 3, 1940, for Crystal pick-up units.

One of the objects of the invention is the provision of an improved pick-up structure in which the crystal is protected by special provision for preventing excessive longitudinal movement orv twisting movement of the chuck.

Another object of the invention is the provision of an improved crystal pickup unit with means for assuring the accurate location of stops on each side of the chuck in order to prevent excessive displacement of the chuck which might cause breakage of the crystal element.

Another object of the invention is an improved adjustable stop for the chuck for a crystal pickup'unit which is adapted to permit the adjustment of the chuck stops to compensate for diameter tolerances which are necessary in the die-cast chuck.

Another object of the invention is the provision of an improved crystal pick-up unit which may be manufactured very economically and which may thus be placed within the means of a larger number of purchasers.

Another object of the invention is the provision of an improved housing for crystal units of the class described, in which the connectors for connecting the crystal unit in circuit are suitably anchored in the housing by an improved structure.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the two sheets of drawings accompanying the specification:

Figure 1 is a top plan view of a phonograph equipped with a pick-up constructed according to the invention;

Figure 2 is an enlarged horizontal sectional view taken through the pick-up with the chuck shown in elevation and taken on the line 2-2 a of Figure 5, looking in the direction of the arrows;

Figure 3 is another enlarged vertical sectional view taken on the plane of the line 3-3 of Figure 2 looking in the direction of the arrows;

Figure 4 is a bottom plan view of a crystal pick-up embodying the invention;

Figure 51s a vertical sectional view taken on the direction of the arrows;

Figure 6 is a rear end view of the pick-up unit; and

Figure 7 is a top plan view of the pick-up unit.

Referring to Figure 1, l0 indicates a support such as the top table of a phonograph housing which may be provided with arotatable turntable II carrying a record l2. The support l0 carries a standard l3 which supports a tone arm "It for substantially universal movement so that the tone arm can be lifted from the record and so that it may traverse the record as it follows the needle groove.

The arm' M may be a'stamped sheet metal member of channel shape closed at each end and it may support the crystal unit or cartridge l5 at such an angle that substantially tangential tracking of the needle can be secured at a point midway between the innermost and outermost grooves of the record.

The pick-up unit l5 may be supported to an arm i l by suitable supporting angles which are secured to a supporting flange i6 that is provided with apertures H for screw bolts or other securing devices.

The pick-up unit I5 is preferably housed in a stamped sheet metal housing indicated in its entirety by the numeral I8. This housing may consist of a lower housing member I 9 and an upper housing member 20, either one of which may carry the supporting flange I6.

The two housing members l9 and 20 may be identical in shape and structure except for the fact that one of these housing members carries the laterally projecting supporting flange l6 and the lowermost of these housing members is provided with an aperture 2| (Fig. 3) for the needle chuck.

In some embodiments of the invention, both the upper and lower housing members may be of similar shape and the supporting flange lt'may be eliminated. Each of these housing members is preferably formed at its ends with the relatively flat attaching flange portions 22, 23, at the left end in Figure 2, and 24 at the right end.

The attaching flange portion 24 is located between a pair of longitudinally extending grooves 25, 26 pressed in the housing member and extending from the outside to the inside. These grooves are for the reception of the insulated conductors 21, 28 which lead to the conductors on the opposite sides of crystals inside the cartridge.

The conductors are for the purpose of impressing the electromotive forces generated by the crystal upon an amplifying system.

The conductors 21, 28 are preferably rubber covered conductors having a live resilient rubber covering of circular cross-section which is slightly larger than the aperture made by the two opposed grooves 25, 26. Thus the rubber covered conductors may be clamped in the grooves by the two half-portions of the housing when the housing is assembled and this end of the housing is sealed against moisture.

For the purpose of assuring the securement of the conductors 21, 28 in the grooves 25, 25, one of each of the grooved housing members may be provided with a transverse ridge or deformation which makes a slight ridge 9l on the inside of each of these two grooves. This ridge 9| further clamps the rubber covered conductors and serves as an anchor.

The ends of the conductors may be directly connected to the foil on the crystals, thus eliminating any necessity for any crystal unit. Each unit may be provided with conductors-of suflicient length for connection to other apparatus.

The attaching flange portions 22 and 23 are in the same plane as the part 24 and, comprise substantially'flat portions of the housing member which are located on the opposite sides of pressed,

partially cylindrical groove 29 formed in this end of each housing and extending from the outside to the interior of the housing.

The groove 29 is for the purpose of receiving a rubber bearing 30 for a chuck trunnion 3|, the rubber bearing 30 being in the form of a tubular resilient rubber member fitting in the groove after it has been applied to the cylindrical chuck trunnion 3|. The trunnion and bearing assembly 30, 3|, is preferably slightly larger than the groove 29 so that when the housing members are assembled to form a bearing aperture at 29, they compress the rubber 30.

The housing members l9 and 29 are preferably formed with'what may be termed a plurality of separate chambers 32, 33, 34. Actually, these chambers are in the form of a plurality of substantially rectangular pan-shaped impressions in the housing in which they are formed for a purpose further to be described.

At the outer edge of each housing member adjacent the open side, the housing is provided with an outwardly extending lip 35, the outermost surface 35 of which is located in the same plane as the attaching flanges 22, 23, 24. This lip is of course not necessary where the supporting flange I6 is located, as that flange serves the same purpose. a

For the purpose of permitting a wider angular adjustment of the cartridge l inside a tone arm [4, one end of the otherwise substantially rectangular supporting flange IB is beveled off at 31, Fig. 1. When the two housing members are secured together, as shown in Fig. 5, the lips 35 -on one side, and the lip 35 and flange IS on the other side engage each other and the attaching flange portions 23, 24 engage the same flange portions on the other housing member in such manner that the housing is completely closed except for connectors on the the conductor grooves 25, 26 and the bearing V groove 29. These are of course closed by the rubber insulated conductors placed in them and by the rubber covered trunnion 3|.

The two housing members are also formed with the diagonally inwardly extending flanges 39, 39 which are joined along aridge 40 except at a point midway between the sides of the cartridge where this ridge 49 and the flanges 38, 39 are varied in shape to form a partially cylindrical groove 41 extending axially of the cartridge. The partially cylindrical grooves 4| in the two housing members form a substantially cylindrical aperture between the chambers 32 and 33 except for the fact that the two ridges 40 do not contact each other internally and the cylindrical opening is not completely defined.

The partially cylindrical surface 4|, however, in each cartridge forms sufficient of a cylindrical bearing to receive a cylindrical bearing portion 42 on the needle chuck 43 when this bearing is covered with a tubular rubber member 44.

The housing members are also provided with inwardly extending flange portions 45, 45 and the flat portion 41 which is spaced inwardly of the upper and lower walls 49, 49 in such manner that flat clamping surface 50 is provided on each housing member. These, flat clamping surfaces 50 are parallel to each other and parallel to the crystals 5 I, 52 and the crystals 5|, 52 are clamped by these surfaces through the agency of the flat resilient deformable clamping blocks 53, 54.

These blocks may be made of rubber or other suitable live resilient material such. as printers roll composition, and the blocks are secured to the clamping surfaces 50 by suitable rubber cement.

The chamber 34 serves as a connection chamber for connecting the conductors 21, 28 to the conducting layers 55, 55, 51 which are outside of and interposed between the crystals 5|, 52.

As the crystal members in the present pick-up unit are disposed in a plane parallel to the plane of the record, they will of course be cut appropriately with respect to the axes of the crystal from which they are made, so that the twisting action of the chuck under the influence of the needle will generate electromotive forces that are collected by means of the conductors 55, 56, 51, and transmitted through conductors 21, 28. The conductors 55, 55, 51, may be connected in various ways, such as series or parallel, as disclosed in my prior Patent No. 2,145,389 of January 31, 1939, according to the characteristics desired.

The crystal member assembly 5|, 52, 55-51, is clamped at its right end between the resilient blocks 53, 54 which are compressed against the crystal assembly by the clamping surfaces 59 of the housings when they are assembled. The size of the resilient blocks 53 and 54 is such that these blocks are suitably compressed when the halves of the housing are assembled as shown in Figure 3. The characteristics of the crystal unit may be predetermined by suitable compression of the resilient blocks 53 and 54.

The other end of the crystal assembly is covered by a strip 60 of liveresilient rubber or printers roll composition of sufficient width to extend be yond the borders of the clamping jaws 6|, 62 of the chuck unit'and of sufficient length so that it may be folded to substantially U-shape about the end of the crystal assembly and interposed between the jaws 69, 62,'and the crystal assembly.

This resilient cushion between the chuck and the crystal assembly is adapted to give predetermined cushioning connection between the crystal assembly and the chuck. The rubber strip 501s compressed and clamped between the opposed jaws il, 62. The pressure placed upon the crystal assembly and rubber strip 50 can be varied or adjusted by the application of pressure to the jaws BI, 52 to bend them into closer engageaaraaae I the rubber striped and crystalas- 4 sembly.

ment with The chuck unit 43 preferably comprises a die- ,cast metal-member which is provided with a substantially cylindrical trunnion 43 at its outer end, acylindricaltrunnion c2 and the clamping jaws The trunnion 63 is provided with an axially extending threaded aperture '53 for receiving the threaded shank 84 of a needlescrew 55 having knurled head 56. I

Threaded aperture $3 communicates with a needle socket aperture 6'5 which is also cylindrical and which is located in a diagonally'downward and forward needle supporting lug as. The needle supporting lug 68 also extends upward slightly at 69 for the purpose of providing sumcient body for the needle socket $1 to communicate with the bore 63 in order that the needle screw 65 may clamp against the needle 10.

The diagonally foward slant of the needle lug $8 and socket 6! is such that it gives the needle a suitable tracking characteristic. That is, the needle is disposed at an obtuse angle to the record, extending backward from the direction of movement. of the record so that it may move along the groove without so much of a tendency to cut in the groove.

The chuck 43 is also provided with a collar ll of larger size than the trunnion 42 and with a frusto-conical portion I2 between the collar H and trunnion 42. conical portion 13 between the trunnion 42 and the clamping flanges GI and 62. The groove or aperture 14 between the clamping flanges 6i and. 62 is preferably of substantially U-shape conforming substantially to the curvature of the rubber strip 60 except that there is a flat rectangular clamping surface 15 on each side of each clamping flange ti and 62 and there is a suitable clearance at 26 over the rest of the groove The housing is also provided with inner diagonally extending surfaces at each end of the cylindrical aperture 4| as indicated at ll. One element of these diagonal surfaces is in the same location as a frusto-conical surface would be. In

some embodiments of the invention, complete frusto-conical surfaces might be provided on both ends of the bearing 4 l, but the diagonally extending surfaces may perform the same function in simpler embodiments of the invention.

The rubber sleeve 64 of live resilient rubber isof such size that it extends over the cylindrical trunnion s2 and frusto- conical surfaces 12, 13,

and by virtue of its tension, conforms itself to these surfaces. The assembly of the trunnion :32 and rubber sleeve 44 is slightly larger than the aperture 4| in which this trunnion is to be mounted. Consequently the rubber sleeve 44 is compressed and engaged at each end of the trunnion between the surfaces I7, 13 and l2, 13.

These surfaces act as thrust surfaces for preventing axial shift of the chuck and the resiliency of the rubber sleeve returns the chuck to its original position after any blow or shock. The amount of compression placed on the rubber sleeve 44, as well as the blocks 53, 54, rubber cushion 60 and rubber sleeve 30, is predetermined for the purpose of securing the most desirable characteristics in the pick-up unit.

The two halves of the housing may be secured together by bolts and nuts or any convenient fastening means, but are preferably permanently It also has another frusto-' a plurality of tubular rivets 13 passing through aperture ld in'the attaching flanges 22, 23 and j 24, and spun or riveted over-on each side-of the flanges. v I

The unit is also preferably providedwith means for providing anadjustable stop limiting the mo tion of-the'chuck t3 and this adjustable mem--- ber 80 may be located on the lower face at of the lower housing member and secured in place bye pair of screw bolts 82 which are threaded I into threaded bores-in thelower housing. This stop member 88'- maycomprise a small sheet metal I member provided with a pair of enlarged apertures as for reception of the screw bolts 32.

The enlarged apertures permit the lateral movement of the stop member-80 on the screw bolts 82 until they are driven home. The stop member 90 may be a strip of metal having a pair of laterally projecting legs 84 separated by a substantially U-shaped notch or groove 85.

The inner surface of the notch or groove acts as a stop surface for the depending lug 68 of the chuck 43. The boundary 85 of the notch acts to limit the effective size of aperture 2| in secured together with these rubber parts in a the lower side of the housing and this stop member definitely limits the amount of lateral displacement of the reproducing stylus.

By means of this adjustable plate, it is possible to provide accurate stops on each side of the chuck to prevent excessive displacement which in turn would readily cause breakage of the crystal element. The plate is preferably adjusted after the entire crystal cartridge assembly has been made and after the chuck assembly has taken its natural position with respect to the strain that is set up inside the assembly and by the compression that is placed upon the rubber and other components.

The notch may be beveled at 86 to correspond in slant at its rear surface to the surface of the depending 111g 68 in some embodiments of the invention.

sive lateral displacement in any of three direc tions. In the other direction the edge surface 81 of the aperture 2! at the front may be made to serve as a stop surface.

In addition to the rubber elements previously described, the unit is also preferably provided with an additional rubber block 90 which is rectangular in plan and elevation and which is compressed between the lower flange 62 of the chuck and the lower wall 49 of the housing.

This block may be made of rubber or printers roll composition and by means of it the resilient torsional characteristics of the assembly. are modified and altered so as to eliminate some undesirable characteristics. This block is also compressed when the unit is assembled and it is secured by cement to the lower housing half. It is preferably of sufficient the full width of the flange 62.

It should also be noted that the thrust surfaces 13, 11, 14, 11 on the chuck may also be located at some other ing 30 in other embodiments of the invention.

It will thus be observed that I have invented an improved crystal unit cartridge which is adapted to be manufactured very economically length to engage over hearing such as the bearbecadse most of its parts are made by stamping operations and there is a minimum amount of machining necessary on any part of the unit. The chucks are die-cast and the unit requires a minimum amount of rubber in its manufacture.

The needle chuck is protected against excessive lateral displacement by positive metallic stops and it is protected against longitudinal displacement, such as might change its characteristics or damage the crystal, by a resilient rubber bearing having thrust surfaces. The present structure protects the crystal element against breakage by pressure or sharp blows on the chuck or needle and the present crystal unit is adapted to give faithful reproduction although it may be manufactured in large quantities at a very low cost.

While I have illustrated a preferred embo'di ment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not-wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a crystal cartridge unit the combination of a housing of rigid material with a crystal secured in said housing and having one end 2. In a crystal cartridge unit the combination of a housing of rigid material with a crystal secured in said housing and having one end clamped by live resilient non-metallic cushions interposed between both sides of the crystal and the housing, a chuck connected to said crystal depending therefrom and extending through an aperture in said housing, and adjustable stop means located at said aperture, said stop means being adjustable after the unit has been completed for the purpose of limiting lateral displacement of the chuck beyond a predetermined point, said stop means comprising a metal plate having a notch surrounding said socket member.

3. In a crystal cartridge unit the combination of a housing of rigid material with a crystal secured in said housing and having one end clamped by live resilient non-metallic cushions interposed between both sides of the crystal and the housing, a chuck connected to said crystal and movably supported in said housing, said chuck having a needle-supporting socket member depending therefrom and extending through an aperture in said housing. and adjustable stop means located at said aperture, said stop means being adjustable after the unit has been completed for the purpose of limiting lateral displacement of the chuck beyond a predetermined point, said stop means comprising a metal plate having a notch surrounding said socket member, said metal plate having enlarged apertures and threaded means passing through said apertures and threaded into said housing for clamping the plate in any of a plurality ofxiitlerent positions.

' clamped by live resilient non-metallic cushions 4. In a crystal unit, the combination of a pair of metallic housing members of substantially similar shape except that one of said housing members is provided with a needle aperture, each housing member being provided with a border rim for engaging the border rim on the other housing to effect a closure at the edges of the housing members and each housing member being' provided with a plurality of flat attaching flanges located at the ends thereof, a crystal unit assembly in said housing including a crystal secured to a chuck, said chuck having tbearings. resilient means interposed between said assembly and said housing and brought into resilient clamping engagement with said assembly when the housing is assembled, and additional resilient and movably supported in said housing, said chuck having a needle-supporting socket member ,meansclamped between the housing and a part of said chuck for adjusting the resilientrcharacteristics of the crystal assembly by effecting a damping action between a flat side of said chuck and a flat part on said housing.

' ROY DALLY.

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