US3219351A - Tone arm lift - Google Patents

Description

Nov. 23, 1965 H. a. sHAPr-:R ETAL 3,219,351

TONE ARM LIFT Filed Nov, 1s, 1961 3 Sheets-Sheet l INVENTORJ' Il HAP/9) 6. VH/IPE? Nov. 23, 1965 H. B. sHAPl-:R ETAL 3,219,351

TONE ARM LIFT Filed Nov. 1s, 1961 s sheets-sheet s United States Patent O 3,219,351 TNE ARR/I LIFT Harry Shaper, East Hills, and .lohn C. Shannon, Hicksville, NX., assignors to Dyna-Empire, Inc., Garden City, Long Island, NSY., a corporation of New York Filed Nov. 13, 1961, Ser. No. 151,625 23 Claims. (El. 274-23) The instant invention relates to phonographs in general and more particularly to magnetic means for lifting the stylus from the record after end of the sound groove has been played.

In high fidelity phonograph equipment the stylus, even though constructed of a diamond, has a very limited life with this life being measured by the time during which the stylus is in engagement with a moving record. Thus, in some phonograph equipment automatic means are provided to halt turntable rotation or to lift the stylus from the record at the end of play. This not only reduces stylus wear but also eliminates annoying sound from the runout groove.

In general, automatic devices of the prior art for this purpose included switch means which required considerable mechanical force for activation thereof. In other prior art devices of this type, a switch requiring a relatively low mechanical operating force was utilized, but in this event the switch acted to control a relay whose contacts were in the operating circuit for the lifting device. For the most part prior art devices of this type were utilized with so-called automatic record changers which operated with relatively high tracking forces.

On the other hand, tone arms utilized With high fidelity turntables are operated with very low tracking forces in the range of from l to 8 grams so that if the tone arm encounters any appreciable mechanical resistance the stylus will jump from the sound grooves and the tone arm will not continue to the end of the record.

The instant invention provides an automatic lift construction which at no time places a mechanical load on the tone arm. That is, all switches of prior art devices for performing this function have been eliminated. This construction is achieved by providing a magnetic lift pin fastened to the tone arm in the region of its pivot. As the arm moves across the record, after the end of the sound groove has been passed, and while the stylus is in the runout groove, the head `of the lift pin enters a shielded magnetic field having a very sharp gradient.

The magnetic field is so shielded that essentially no force is exerted on the tone arm while the stylus is in the sound groove. However, the lift pin is so constructed and the magnetic iield is so shaped that only a very slight, if any, side-wise pull is exerted on the pin while the `stylus is in the runout groove. Even with the lift pin well within the magnetic field the side-wise pull is negligible. The pin is provided with an undercut so that essentially all forces are directed vertically upward to lift the stylus from the record more delicately than is possible with the human hand.

The shielded steep gradient magnetic field is achieved by utilizing a permanent magnet positioned within a housing of high magnetic permeability with the side of the housing having a rectangular opening through which the tone arrn lift pin enters. The magnet is positioned above the opening with one of the pole faces of the magnet being substantially in line with the upper boundary of the zopening. The pin head is rectangular in shape being substantially smaller than the size of the housing opening. With the stylus resting on a record the bottom surface of the pin just clears the bottom boundary of the opening. Because of this, side-wise pull on the pin is substantially eliminated and vertical pull is not eifective until such time as the pin head is fully within the housing.

3,219,351 Patented Nov.. 23, 1955 Accordingly, a primary object of this invention is to provide a novel device for automatically lifting a phonograph stylus from a record at the conclusion of play.

Another object is to provide a device of this type which does not present any mechanical load to the tone arm which must be overcome by tracking of the stylus in a record groove.

Still another object is to provide a device of this type which utilizes a permanent magnet.

A further object is to provide a device of this type in which there is a steep gradient shielded magnetic field.

A still further object is to provide a device of this type including a magnet disposed within a shielding housing in such a position that a pin mounted to a tone arm will, upon entering the housing through an opening, be subjected to a pull which is substantially vertical.

These as well as other objects yof this invention shall become readily apparent after reading the following description of the accompanying drawings, in which:

FIGURE l is a perspective illustrating a phonograph including the device of the instant invention.

FIGURE 2 is a fragmentary plan view of the phonograph of FIGURE l with the :stylus lifted from the record.

FIGURE 3 is a side elevation, partially sectionalized, illustrating the mounting of the magnet and its shielding housing.

FIGURE 4 is a cross section taken through line 4 4 of FIGURE 3 looking in the direction of arrows 4 4.

FIGURE 5 is a perspective illustrating the shielding housing.

FIGURE 6 is a side elevation illustrating the two positions which the shielding housing may assume.

FIGURE 7 is a perspective illustrating the lift pin mounted to a tone arm.

FIGURE 8 is a fragmentary perspective of a tone arm illustrating the lift pin mounting of another embodiment of this invention.

FIGURE 9 is a side elevation of the magnet and its mounting for the embodiment of FIGURE 8.

FIGURE 9-A is a plan view of the elements shown in FIGURE 9.

FIGURE 9-B is a cross-section taken through line RiB-9B of FIGURE 9-A looking in the direction of arrows 9B-9B- Now referring more particularly to FIGURES 1 7. Phonograph 10 includes hollow rectangular base 1l having mounting bo-ard 12 forming the top thereof. Turntable 13, mounted to board 12 for rotation about axis 14, is operated through a suitable drive mechanism (not shown) well known to the art. A portion of this drive mechanism projects into housing extension 15 mounted on the top side of board 12.

Tone arm 16 is mounted to post assembly 17 for pivotal movement about a vertical axis. Tone .arm 16 is also mounted to assembly 18 rfor pivotal movement about a horizontal axis. The portion of tone arm 16 to the rear of its pivots is provided with counterweight 19 while the forward end of tone arm 16 is provided with a removable shell 20 within which phonograph pickup cartridge 21, including stylus 22, is mounted. Arm rest 23, mounted to the top surface of board 12, is provided for storing tone arm 16 when a record is not being played.

As seen in FIGURE 2, disk phonograph record 24 is provided with a continuously spiraling soun-d groove in the region between the peripheral edge of record 24 and the end portion 25 of the sound groove. For all practical purposes the minimum `distance between the end 25 of the sound groove and the center of record 24 conforms to an industry standard. The end 2-5 of the sound groove is connected by one or more spiraling runout grooves 26 to the final circular closed groove 27. Since conventional high fidelity turntable equipment is usually not provided with any automatic means to lift the stylus from the record after the last end of the sound groove has been reached, record 24 continues to rotate with stylus 22 riding in the last groove 27 to produce an offending repetitious noise. Further, during the time that record 24 is rotating with stylus 22 in groove 27 stylus 22 is being subjected to needless wear.

In order to alleviate this condition, the instant invention provides permanent magnet 29 which attracts lift pin 30 mounted to tone arm 16 to lift stylus 22 off of record 24 after the end 25 of the sound groove has been passed.

Lift pin 30 is secured at the end thereof opposite head 31 to tone arm 16 in the region of assembly 17 and slightly forward thereof. That is, the shank of pin 30 extends through a transverse aperture of tone arm 16 with the threaded shank end remote from head 31 being engaged by cap nut 32a. At least the head 31 of pin 30 is constructed of magnetic material. The surface 32 of head 31 most remote from tone arm 16- is generally square land is positioned in a vertical plane.

Magnet 29 is generally cylindrical with the magnet poles being in horizontal planes at the ends of the cylinder. Cylindrical tubular housing 33 surrounds magnet 29 and is constructed of material having a high magnetic permeability. Magnet 29 is mounted to cover 34 at the upper end of housing 33 with magnet 29 positioned coaxially with housing 33. Housing 33 is provided with a square aperture 35 through which lift pin head 31 may enter. Magnet 29 is so positioned that the bottom pole face thereof is in a horizontal plane which is extremely close to the top-side of aperture 35.

As best seen in FIGURE 3, pivot member 36 extends into housing 33 through the bottom opening thereof. Roll pin 37 extends through a clearance aperture of pivot member 36 with the ends of roll pin 37 being supported by the portions defining aligned apertures in housing 33. Pivot member 36 is provided with a downward extension 3S by means of which member 36 is ixedly secured to one end of horizontal support plate 39. The other end of support plate 39 is xedly mounted to collet 40 of post assembly 17. The upper end of collet 40 houses ball bearings 41 which support shaft 42 which constitutes the vertical pivotal axis for tone arm 16. Housing cover 43 for assembly 18 is mounted to the upper end of shaft 42.

Housing 33 is pivotable about pin 37 between the solid and dotted line positions of FIGURE 6, with the engagement of angled surface 4S with support plate 39 establishing the dotted line position. Free ends 45, 46 of spring 44 are disposed within apertures of housing 33 while the lower loop of spring 44 is disposed within depression 47 of member 36. The action of spring 44 exerts a friciton load on pin 37 sufficient to maintain housing 33 in its adjusted position.

With housing 33 in the solid line position of FIGURE 6 aperture 35 is so positioned that with stylus 22 riding on record 24, as lift pin 30 enters housing 33, the bottom edge of pin head 31 will just clear the bottom boundary of aperture 35. The construction of housing 33 and placement of magnet 29 therein is such that the magnetic field has a very steep gradient with substantially all, if not all, lines of flux being within the confines of housing 33. Lift pin 30 is so positioned on tone arm 16 that pin head 31 is not fully entered into housing 33 until after stylus 22 has passed the end 25 of the sound groove and is in the runout groove 26. Thereafter, but before stylus 22 can enter the last groove 27, pin head 31 is in the portion of the magnetic field where the magnetic forces exert a substantially upward force on pin head 31 thereby lifting stylus 22 from record 24.

Because of the shielding effect of housing 33 essentially no sidewise force is exerted upon pin 30 while stylus 22 is in the sound groove. With housing 33 in the dotted line position of FIGURE 6 magnet 29 is so positioned that it is totally ineffectual for operation with tone arm playing a standard size record.

The embodiment of this invention hereinbefore described is intended to be built into new equipment. FIGURES 8-9B illustrate an embodiment which is adapted to be added to existing equipment.

Now referring more particularly to FIGURES 8-9'B. Lift pin 71 includes a threaded shank 72 with enlarged square head 73 of magnetic material at one end of shank 72. The other end of shank extends through a threaded aperture in U-shaped clamp 74 and bears against tone arm 75 which extends between the arms of clamp 74. Lift pin 71 serves as a means for rmly mounting clamp 74 to tone arm 75 without the necessity for drilling any holes therein.

Rod magnet 76 is mounted at its upper end to the top 77 of cylindrical housing 7S. The bottom pole face of magnet 76 is substantially in line with the top edge of square aperture 79 through which pin head 73 enters housing 78. The lower end of housing is held within collet 79a by means of set screw Si). The lower end of collet 79a extends through an aperture in support plate 81 with the lower end of collet being outwardly flared to xedly connect collet 79a to plate 81.

Rivet 82 pivotally mounts plate 81 to upper offset leg 83 of bracket 85. Leaf spring S6 is positioned below plate 81 and is mounted thereto by means of rivet 82 in such a manner that detent ball 87 is captured within an undersized aperture of plate 81. Ball 87 projects beyond the upper surface of plate 81 and is enterable into plate apertures 88, 89 of bracket leg 83 to maintain housing 78 in either one of two adjusted positions.

Bracket is provided with offset oppositely extending lower legs 91, 92. Each leg 91, 92 is provided with a short arcuate slot 93. Screws 94, extending through slots 93 and received by threaded apertures (not shown) in the base 95 of post assembly 17, mount bracket S5 to assembly 17. The threaded apertures are so positioned and slots 93 are so shaped that bracket 85 is arcuately movable about the vertical axis of post assembly 17 as a center.

In general, with ball 87 in aperture 88 magnet 76 is ineffective While with ball 87 within aperture 89 housing 78 is so positioned that magnet 76 functions in the manner of magnet 29 with housing 33 in the solid line position of FIGURE 6. Lines A, B, C are placed next to slot 93 of leg 91 to indicate the required position of slot 93 relative to screw 94 to properly position magnet 76 for use with different standard size records.

It is to be noted that the utilization of clamp 74 t0 mount lift pin 71 enables the latter to be appropriately positioned along the length of tone arm 75. Further, the utilization of set screw 80 enables the height of housing 78 and the angular position of aperture 79 to be readily adjusted.

Thus, this invention provides a magnet within a shielding housing so shaped that the magnetic field is substantially confined within the housing. Further the magnetic eld gradient is so steep that it exerts a substantially vertical pull on a magnetic pin entering the housing through a side aperture. While this invention has been described as lifting the tone arm when the stylus is in the runout groove, it is to be understood that the elements may be arranged so that lifting is delayed until the stylus is in the last groove.

The features and principles underlying the invention described above in connection with specific exemplifications thereof, will suggest to those skilled in the art many other modifications thereof. It is accordingly desired that the appended claims shall not be limited to any specific features or details described in connection with the exemplifications thereof.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows.

1. In a device of the class described, an arm, first means defining a vertical axis about which said arm is pivotable, second means defining a movable horizontal axis about which said arm is pivotable, said second means mounted for pivotal movement about said vertical axis, a magnetic member carried by said arm, a magnet, third means constructed of material having a relatively high magnetic permeability and operatively positioned for shielding said magnet in a manner such that its magnetic field is confined so that said magnet will exert substantially no force will be exerted upon said magnetic member by said magnetic field until said arm, when moving about said vertical axis in a first direction toward said magnet, has shielding said magnet in a manner such that is magnetic field almost immediately thereafter being effective to act upon said magnetic member and thereby move said arm essentially upward about said horizontal axis.

2. The device of claim 1 in which the third means comprises a housing wherein said magnet is disposed, said housing having a side aperture positioned to receive said magnetic member.

3. The device of claim 2 in which the lowermost portion of the magnet is positioned no lower than the uppermost boundary of said aperture.

4. The device of claim 3 in which the aperture is of generally rectangular shape.

5. The device of claim 4 in which the magnetic member includes a first portion, generally rectangular in shape, which is first to enter through said aperture.

6. The device of claim 5 in which the first portion while moving through said aperture is closer to the bottom than to the top boundary of the aperture.

7. The device of claim 2 in which the magnet is a vertically positioned rod.

8. The device of claim 2 in which the housing is a vertically positioned tubular member surrounding said magnet and coaxial therewith.

9. The device of claim 8 in which the lower pole face of the magnet is no lower than the uppermost boundary of the aperture.

10. The device of claim 9 in which the aperture is of generally rectangular shape, said magnetic member including a first portion, generally rectangular in shape, which is first to enter through said aperture, said first portion while moving through said aperture being closer to the bottom than to the top boundary of the aperture.

11. The device of claim 2 in which the ho using and magnet are selectively movable to a first and a second position, said magnet when in said first position being operatively positioned so that said magnet will exert substantially no force upon said magnetic member until said arm, when moving in said first direction toward said magnet, has reached a predetermined angular position, said magnet when in said second position being operatively positioned so as not to lift said arm almost immediately after said arm has passed the predetermined angula-r position.

12. The device of claim 2 in which the magnet is mounted to said housing internally thereof, an axis about which said magnet and said housing are movable between a first and a second position, said magnet when in said first position being operatively positoned so that said magnet will exert substantially no force upon said magnetic member until said arm, when moving in said first direction toward said magnet, has reached a predetermined angular position, said magnet when in said second position being operatively positioned so as not to lift said arm almost immediately after said arm has passed the predetermined angular position.

13. In combination a phonograph turntable, support means, means rotatably mounting said turntable to said support means on a first side thereof, a tone arm, first means extending above said first side and mounting said tone arm near the rear of' said tone arm to said support means, said first means defining vertical and horizontal pivotal axes for said tone arm with said horizontal axis pivotable about said ve-rtical axis, a pickup cartridge including a stylus mounted to said tone arm near the front thereof, second means including a first and a second section, said first section including a magnet for lifting said stylus free of a disc record on said turntable when said tone arm has reached a predetermined angular position where the stylus is at a point on this record between the center of the record and the sound groove positioned closest to the center, said first section also including a housing constructed of material having high magnetic permeability, said magnet being disposed within said housing, said second section including a magnetic member, one of said sections mounted to said tone arm and the other of said sections mounted to said support means and extending above said first side, said housing constructed and positioned such that said magnet is ineffectual to exert a force on said magnetic member While said stylus is in a sound groove of a record on said turntable and is positioned such that the magnet exerts a force on the magnetic member lifting said tone arm after said stylus has moved past the end of such sound groove closest to the axis of rotation for the turntable.

14. The combination of claim 13 in which the magnetic member includes a lift pin projecting horizontally from said tone arm toward the housing, said housing including an aperture through which said lift pin is entered when said tone arm is in said predetermined angular position.

1S. The combination of claim 14 in which the magnet is a rod with pole faces at the ends thereof, said magnet having one pole face above the other with the other pole face positioned no lower than the uppermost boundary of said aperture.

16. The combination of claim 14 in which the rod is cylindrical and said housing includes a cylindrical portion coaxial with the rod, said aperture being in the side of the cylindrical portion.

17. The combination of claim 15 in which the aperture is of generally rectangular shape, said pin mounted at one of its ends to said tone arm and at its other end having a generally rectangular head, said head while moving through said aperture being closer to the bottom than to the top boundary of the aperture.

18. The combination of claim 14 in which the housing and the magnet are selectively movable as a unit, said magnet when in said first position being effective to bring about the action previously described, said magnet when in said second position being ineffectual to lift said arm almost immediately after said arm has passed the predetermined angular position.

19. In a device of the class described having an arm, first means supporting said arm near one end thereof in a manner such that the other end is movable in a generally horizontal plane between a first and a second position, the improvement comprising a second means including a first and a second section; one of said sections mounted to said arm; third means mounting the other of said sections remote from said arm in a predetermined position relative to said first means; said first section including a magnet and said second section including a magnetic member; said magnetic member coming under the influence of said magnet and in so doing causing said magnet to generate a force lifting said other end of said arm from said plane after said arm, when moving from said first toward said second position, has reached a predetermined third position intermediate said first and said second positions; said second means also including a stationary magnetic shield interposed between said magnet and said magnetic member as said other end of the tone arm moves from said first position toward said third position to prevent said magnet from attracting said magneic member while said other end is between said first and third positions.

24). The device of claim 19 in which the shield is constructed and positioned such that said magnet generates a I eld having a very steep gradient oriented to exert a substantially vertical force on said other end only after said arm has reached said third position.

21, In combination a housing constructed of material having high magnetic permeability, a magnet having a pair of pole faces disposed within said housing, said housing having a side aperture positioned such that the top boundary thereof is no higher than the one of said pole faces which is closest to said aperture, and a magnetic member mounted for movement through said aperture, said housing operatively constructed to shield said magnetic member from flux generated by said magnet until said member enters said housing.

22. In combination a cylindrical housing constructed of permeability having high magnetic material, a closure member at one end of said housing, a rod magnet positioned within said housing and coaxial therewith, said magnet mounted to said closure member and having pole faces at opposite ends thereof, said housing including a side aperture positioned so that with said closure member at the top of said housing the upper boundary of said aperture is no higher than the lower pole face of said magnet, and a magnetic member mounted for movement through said aperture, said housing operatively constructed to shield said magnetic member from ux generated by said magnet until said member enters said housing.

23. The combination of claim 22 in which there is a mounting device which supports said housing, means including a pivot connecting said housing to said mounting device in a manner such that said housing is movable about said pivot between a first and a second position relative to said mounting device, said side aperture moving away from said magnetic member as said housing moves from said first position to said second position.

References Cited by the Examiner UNITED STATES PATENTS 2,939,715 6/1960 Krahulec 274-14 LOUIS J. CAPOZI, Primary Examiner.

ANTONIO F, GUIDA, Examiner.

Claims (1)

13. IN COMBINATION A PHONOGRAPH TURNTABLE, SUPPORT MEANS, MEANS ROTATABLY MOUNTING SAID TURNTABLE TO SAID SUPPORT MEANS ON A FIRST SIDE THEREOF, A TONE ARM, FIRST MEANS EXTENDING ABOVE SAID FIRST SIDE AND MOUNTING SAID TONE ARM NEAR THE REAR OF SAID TONE ARM TO SAID SUPPORT MEANS, SAID FIRST MEANS DEFINING VERTICAL AND HORIZONTAL PIVOTAL AXES FOR SAID TONE ARM WITH SAID HORIZONTAL AXIS PIVOTABLE ABOUT SAID VERTICAL AXIS, A PICKUP CARTRIDGE INCLUDING A STYLUS MOUNTED TO SAID TONE ARM NEAR THE FRONT THEREOF, SECOND MEANS INCLUDING A FIRST AND A SECOND SECTION, SAID FIRST SECTION INCLUDING A MAGNET FOR LIFTING SAID STYLUS FREE OF A DISC RECORD ON SAID TURNTABLE WHEN SAID TONE ARM HAS REACHED A PREDETERMINED ANGULAR POSITION WHERE THE STYLUS IS AT A POINT ON THIS RECORD BETWEEN THE CENTER OF THE RECORD AND THE SOUND GROOVE POSITIONED CLOSEST TO THE CENTER, SAID FIRST SECTION ALSO INCLUDING A HOUSING CONSTRUCTED OF MATERIAL HAVING HIGH MAGNETIC PERMEABILITY, SAID MAGNET BEING DISPOSED WITHIN SAID HOUSING, SAID SECOND SECTION INCLUDING A MAGNETIC MEMBER, ONE OF SAID SECTIONS MOUNTED TO SAID TONE ARM AND THE OTHER OF SAID SECTIONS MOUNTED TO SAID SUPPORT MEANS AND EXTENDING ABOVE SAID FIRST SIDE, SAID HOUSING CONSTRUCTED AND POSITIONED SUCH THAT SAID MAGNET IS INEFFECTUAL TO EXERT A FORCE ON SAID MAGNETIC MEMBER WHILE SAID STYLUS IS IN A SOUND GROOVE OF A RECORD ON SAID TURNTABLE AND IS POSITIONED SUCH THAT THE MAGNET EXERTS A FORCE ON THE MAGNETIC MEMBER LIFTING SAID TONE ARM AFTER SAID STYLUS HAS MOVED PAST THE END OF SUCH SOUND GROOVE CLOSEST TO THE AXIS OF ROTATION FOR THE TURNTABLE.

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