US3774918A - Phonograph pickup stylus - Google Patents

Phonograph pickup stylus Download PDF

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Publication number
US3774918A
US3774918A US00232892A US3774918DA US3774918A US 3774918 A US3774918 A US 3774918A US 00232892 A US00232892 A US 00232892A US 3774918D A US3774918D A US 3774918DA US 3774918 A US3774918 A US 3774918A
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US
United States
Prior art keywords
stylus
vertex
conical
cut
edge line
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00232892A
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English (en)
Inventor
N Shibata
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Victor Company of Japan Ltd
Original Assignee
Victor Company of Japan Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP46013537A external-priority patent/JPS4937526B1/ja
Priority claimed from JP7984671A external-priority patent/JPS5017845B2/ja
Priority claimed from JP7984571A external-priority patent/JPS4846304A/ja
Application filed by Victor Company of Japan Ltd filed Critical Victor Company of Japan Ltd
Application granted granted Critical
Publication of US3774918A publication Critical patent/US3774918A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B3/00—Recording by mechanical cutting, deforming or pressing, e.g. of grooves or pits; Reproducing by mechanical sensing; Record carriers therefor
    • G11B3/44—Styli, e.g. sapphire, diamond
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B3/00—Recording by mechanical cutting, deforming or pressing, e.g. of grooves or pits; Reproducing by mechanical sensing; Record carriers therefor
    • G11B3/44—Styli, e.g. sapphire, diamond
    • G11B3/46—Constructions or forms ; Dispositions or mountings, e.g. attachment of point to shank

Definitions

  • This invention relates to a phonographpickupstylus, and more particularly to a phonograph pickup stylus for reproducing sound from a record disc.
  • the stylus is capable of contacting each of the two walls of a sound groove of the record disc with a contact surface figure which is short in the longitudinal direction of the groove and longin the transverse or depth direction extending toward the bottom of the groove.
  • a round stylus has a tip of spherical shape.
  • the perimeter of the contact surface of the stylus and each record groove wall has a circular contour.
  • the term contact surface contour is herein used to designate the surface contour where the stylus contacts the groove wall when itis held in the groove with a specific stylus pressure. This pressure causes the part of the groove wall thus contacted to undergo a plastic deformation, whereby the stylus is in a state wherein it is pressing into the groove wall.
  • the contact surface contour is a relatively large circular figure. For this reason, a round stylus cannot reproduce, in a fully satisfactory manner, signals of relatively high frequencies recorded in the form of small waveforms in the groove walls.
  • an elliptical stylus has been proposed and used.
  • This elliptical stylus has a shape produced by grinding the front and rear sides of a round stylus thereby giving the cross section thereof an elliptical shape.
  • the term front and rear sides is herein used to designate the front side and rear side of the stylus advancing relatively to the sound groove.
  • the contact surface contour of the stylus and each groove wall is made an elongated ellipse with its shorter dimension in the longitudinal direction of the groove. Its longer dimension, in the transverse direction or the depth direction extending toward the bottom of the groove along the groove wall (hereinafter referred to simply as depth direction), and the area of this contact surface contour is made large.
  • the stylus does not bite into the groove wallsuBy the use of the stylus which forms a contactsurface figure of the above described shape, it is possible to reproduce signals of high frequency with excellent signal to noise ratio.
  • Another object of this invention is to provide a phonograph pickup stylus of a shape whereby it can contact each wall of the sound groove of the record disc with a contact surface contour of a shape which is short in the longitudinal direction of the groove and long in the depth direction.
  • a further object is to provide a phonograph pickup stylus, having a curved surface part for making contact with a record groove wherein the surface is made by merely subjecting it to a plane cutting.
  • curved parts have a large radius of curvature in the vertical section of the stylus in its state of use.
  • the phonograph pickup stylus according to the invention can be produced easily and at low cost.
  • FIG. 1 is a side view of the tip of a stylus, showing how it is cut during fabrication, for illustrating a first
  • FIG. 3 is a side view of the tip of a stylus, showing how it is cut during fabrication, for illustrating a second embodiment of a stylus according to the invention
  • FIGS. 4A and 4B are respectively a side view and a front view showing a fabricated stylus of the second embodiment
  • FIGS. 5 and 6 are respectively side views of the tip of a stylus showing how it is cut during fabrication, for illustrating a third embodiment of a stylus according to the invention
  • FIGS. 7A, 7B and 7C are respectively a side view, a front view and a bottom view of the fabricated stylus of the third embodiment.
  • FIGS. 8A and 8B are respectively a vertical cross section showing the stylus of the third embodiment in the state of contact with the walls of a sound groove of a record disc,'and a developed cross-sectional view of a section of the stylus of the third embodiment taken perpendicularly to the groove walls at the contact surface between the stylus and the groove walls.
  • the first em bodiment of the stylus according to the present invention is fabricated by first grinding the extreme end of a diamond stylus body of the initial shape of a square bar into a cone of a vertex angle of 60.
  • the tip of the conical part thus ground is shown in FIG. 1.
  • the conical stylus body 10 thusobtained is orientated by tilting its axis 12 so that the plane 11 along which it is to be cut is vertical.
  • the cut plane 11 is inclined by a specific angle (less than 90) relative to the axis 12. Plane 11 then passes through a point 14 which is offset by a distance in the order of from 12 to 15 microns on the profile line a on one side, as shown in FIG. 1. This distance is measured from the vertex 13 of the conical stylus body 10. At the same time, plane 11 passes through a point 15 spaced apart by a substantial distance from the vertex and disposed on the conical profile line 1012 on the other side of the stylus body 10. The portion of the conical stylus structure including the vertex 13 and partitioned by the cut plane 11 is then ground off and removed.
  • a stylus 17 is shaped as indicated by the side view of FIG. 2A and by the front view of FIG. 2B.
  • the shape of the resulting contour along the cut plane 11 on the stylus body is an ellipse.
  • An elliptical edge line 18 is thus defined by the cut plane 11 and the conical outer surface of the stylus.
  • the edge thereof is rounded with a small, constant radius of curvature of the order of from 5 to 10 microns, for example, in planes perpendicular to the edge, whereupon the phonograph pickup stylus 17 is completed.
  • This pickup stylus 17 is placed in a sound groove of a record disc 19 with an orientation such that the cutplane 11 is vertical and perpendicular to the groove as shown in FIG. 2B,.
  • the angle formed by the tangent lines at the points P, P of the stylus l7 is substantially equal to the angle between the two walls of the groove 20.
  • the radius of curvature of the curve of the edge line 18 at each point P and the parts in the vicinity thereof is large, being of the order of 75 microns, for example. Accordingly, the stylus 17 contacts each wall of the groove 20 with a contact surface figure of a shape which is short in the longitudinal direction of the groove and long in the depth direction thereof.
  • a stylus body 10 is first prepared with a conical end, in the same manner as described above with respect to the first embodiment. Then it' is orientated by tilting its axis 12 as that a plane is vertical. The stylus structure is to be cut along this path.
  • the cut plane 30 is inclined relative to the axis 12 by a specific angle 6' (equal to 5a of the vertex angle of the stylus, namely 30 in this embodiment). Furthermore, this cut plane 30 passes through a point 31 which is offset by a distance in the order of from 12 to 15 microns on the profile line 10a on one side from the vertex 13 of the conical stylus body 10. At the same time, cut plane 30 is parallel to th profile of 10]) on the other side of the stylus body.
  • the portion of the stylus body including the vertex 13 is cut off where partitioned by the cut plane 30.
  • the cut off is preferably removed by grinding.
  • a stylus 33 as indicated by the side view of FIG. 4A and the front view of FIG. 4B is obtained.
  • the shape of the resulting figure along the cut plane 30 on the stylud body is a parabola.
  • a parabolic edge line 34 is thus defined by the cut plane 30 and the conical outer surface of the stylus.
  • edge line 34 In and along the lower portion of this edge line 34, the edge thereof is rounded with a small, constant radius of curvature in the order of from 5 to 10 microns, for example, in planes perpendicular to the edge, whereupon the phonograph pickup stylus 33 is completed.
  • the present invention solves this problem in a third embodiment thereof as described below.
  • a stylus body 10 with a conical end of a vertex angle of is prepared similarly to the above described embodiments and is disposed so that its centerline axis 12 is vertical.
  • the portion 16 including the vertex 13 is cut off along the line partitioned by the cut plane 11 passing through the points 14 and 15.
  • the cut off part is removed by grinding, whereupon a cut face 11 is obtained on the stylus.
  • a resulting stylus 40 appears as shown in FIG. 6 when it is rotated toward the viewer through an angle of 60 from its state as shown in FIG.
  • the stylus 40 is then subjected to another cutting operation.
  • a part 43 thereof is cut off and removed by grinding along a cut plane 42 passing through a point 41 of the same height as the point 15 on the profile line,
  • the edge lines 46 and'47 are symmetrical with respect to the intersection line between the cut planes 1 l and 42.
  • the stylus 44 When the stylus 44 is lowered into the groove of the record disc 19, as indicated in FIG. 8A, the two side points Q, Q and the parts in the vicinity thereof, on these edge lines 46 and 47, make contact with the opposite walls of the groove.
  • Theradius of curvature of the curved edge lines 46 and 47 at these points 0, Q and the parts in the vicinity thereof is greater than, for example, the corresponding radius of curvature (approximately 75 microns) in each of the preceding embodiments. Of course, it is also greater than the radius of an imaginary circle 49 tangentially in contact with tangent lines passing through the points Q, Q as viewed in FIG. 8A. Accordingly, the stylus 44 makes contact with the record groove 20 along a contact surface contour which is short in the longitudinal direction of the groove and long in the depth direction thereof.
  • the stylus 44 when the centerline axis 12 of the stylus 44 is in a state wherein it is perpendicular to the record disc, the tangent to the edge line 46 (or 47) at the point 0 is perpendicular to the record disc and parallel to the axis 12. Accordingly, in order to cause the stylus 44 make contact with the record groove, in a manner which conforms to the groove walls in the depth direction thereof, without tilting the points 0, Q and the parts in the vicinity thereof of the edge lines 46 and 47, the stylus is held in a position wherein its axis 12 is vertical.
  • the stylus 44 of this third embodiment differs from the styluses 17 and 33 of the preceding embodiments in that the procedure of installing the stylus 44 in the pickup cartridge is greatly facilitated since the points Q, Q and the parts in the vicinity thereof conform accurately to the groove wall contour in the depth direction thereof when the stylus is used with its axis vertically orientated.
  • two plane cuttings are made to produce the cut faces 11 and 42 respectively inclined relative to profile side lines of the stylus body.
  • the cutting procedure of the second embodiment may be applied to cause a cut fact to be par allel to a side line of the stylus body.
  • the edge line formed by the cut face and the outer conical surface of the stylus body constitutes a part of a parabola.
  • the plane cutting of the stylus body can be accomplished by any suit able known grinding method. That is, for example, the
  • grinding can be carried out by applying the stylus body against a rotating grinding disc on which an abrasive such as powdered diamond has been deposited.
  • the principal features of the phonograph pickup stylus according to the present invention may be enumer ated as follows.
  • the pickup stylus makes contact with the walls of the record groove with a contact surface contour which is short in the longitudinal direction of the groove and long in the depth direction thereof, the stylus can reproduce even high-frequency signals with a large signal to noise ratio. Moreover, since the contact area is large, there is little possibility of damage to the record groove, whereby the serviceable life of the record disc is prolonged.
  • the record disc softens when its temperature becomes high, and the above mentioned resonance frequency fluctuates greatly with temperature.
  • the resonance frequency is readily affected by the temperature since is is a relatively low frequency.
  • the resonance point which fluctuates with temperature is outside of the frequency band used and, as a result, is not subject to the effect of temperature variations.
  • a phonograph pickup stylus comprising a conical stylus body having at least one plane cut face formed by removing material from said conical body along at least a single cut portion of the stylus body, the removed material including the conical vertex thereof and being partitioned from the remainder of the body by at least one intersecting plane inclined at a specific angle 0 (less than relative to the centerline axis of the body passing through the vertex, an edge line being formed at the intersection between said plane cut face and the outer conical surface of the body, the angle be tween tangents at two side points of said edge line near the tip part thereof being substantially equal to the dihedral angle between the opposed side walls of a record disc groove in which the stylus is placed in operation whereby said side points and the parts in the vicinity thereof contact said groove, and the radius of curvature of the edge line at the side points and the parts in the vicinity thereof being greater than the radius of an imaginary circle tangentially inscribed between the edge line at the two side points.
  • a phonograph pickup stylus comprising a conical stylus body having two out faces formed by removing a portion of the stylus body, the removed portion including the conical vertex thereof and being partitioned from the remainder of said body by two intersecting planes inclined at a specific angle (less than 90) each relative to the centerline axis of the body passing through the vertex, said two intersecting planes forming a dihedral angle therebetween at their intersection, the intersections between the two edge lines formed by said two cut faces and the edge lines at the outer conical surface of the body having a symmetrical shape with respect to said intersection between said two planes, the angle between tangents at two side points of said edge lines near the tip part thereof being substantially equal to the dihedral angle between the opposed side walls of a record disc groove in which the stylus is placed in operation whereby said side points and the parts in the vicinity thereof make contact with said groove, and the radius of curvature of the edge lines at the side points and the parts in the vicinity thereof being greater than the radius of an imaginary circle
  • a phonograph stylus comprising an initially conical tip having a portion of the cone removed, said portion having at least one flat surface forming an elliptical conical section dividing the vertex of said cone from the stylus.

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  • Grinding And Polishing Of Tertiary Curved Surfaces And Surfaces With Complex Shapes (AREA)
  • A Measuring Device Byusing Mechanical Method (AREA)
  • Optical Head (AREA)
  • Forging (AREA)
US00232892A 1971-03-13 1972-03-08 Phonograph pickup stylus Expired - Lifetime US3774918A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP46013537A JPS4937526B1 (enrdf_load_stackoverflow) 1971-03-13 1971-03-13
JP7984671A JPS5017845B2 (enrdf_load_stackoverflow) 1971-10-12 1971-10-12
JP7984571A JPS4846304A (enrdf_load_stackoverflow) 1971-10-12 1971-10-12

Publications (1)

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US3774918A true US3774918A (en) 1973-11-27

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US00232892A Expired - Lifetime US3774918A (en) 1971-03-13 1972-03-08 Phonograph pickup stylus

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US (1) US3774918A (enrdf_load_stackoverflow)
DE (1) DE2211823C3 (enrdf_load_stackoverflow)
GB (1) GB1383238A (enrdf_load_stackoverflow)
NL (1) NL163038C (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3871664A (en) * 1973-05-29 1975-03-18 Diamagnetics Inc Phonograph stylus
US4164755A (en) * 1976-09-13 1979-08-14 Rca Corporation Video disc pickup apparatus
US4521877A (en) * 1982-02-02 1985-06-04 Namiki Precision Jewel Co., Ltd. Reproducing stylus and method of making same
EP0253769A3 (de) * 1986-07-09 1989-07-05 Fritz Gyger, Jr. Abtastnadel

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2732533C3 (de) * 1976-08-27 1981-10-01 Gyger, Fritz, Gwatt b. Thun Abtastnadel zum Abtasten einer Tonrille für Stereo- oder Quadrophonie

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2534735A (en) * 1945-01-19 1950-12-19 Dictaphone Corp Guarded stylus
US2699720A (en) * 1950-04-13 1955-01-18 Winfield S Brooks Half tone engraving process
GB768414A (en) * 1954-06-18 1957-02-13 Pathe Marconi Ind Music Improvements in and relating to gramophone needles

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2534735A (en) * 1945-01-19 1950-12-19 Dictaphone Corp Guarded stylus
US2699720A (en) * 1950-04-13 1955-01-18 Winfield S Brooks Half tone engraving process
GB768414A (en) * 1954-06-18 1957-02-13 Pathe Marconi Ind Music Improvements in and relating to gramophone needles

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3871664A (en) * 1973-05-29 1975-03-18 Diamagnetics Inc Phonograph stylus
US4164755A (en) * 1976-09-13 1979-08-14 Rca Corporation Video disc pickup apparatus
US4165560A (en) * 1976-09-13 1979-08-28 Rca Corporation Method for manufacturing a diamond stylus for video disc players
US4521877A (en) * 1982-02-02 1985-06-04 Namiki Precision Jewel Co., Ltd. Reproducing stylus and method of making same
EP0253769A3 (de) * 1986-07-09 1989-07-05 Fritz Gyger, Jr. Abtastnadel

Also Published As

Publication number Publication date
NL163038B (nl) 1980-02-15
NL163038C (nl) 1980-07-15
NL7203183A (enrdf_load_stackoverflow) 1972-09-15
DE2211823C3 (de) 1975-04-17
GB1383238A (en) 1975-02-05
DE2211823A1 (de) 1972-10-12
DE2211823B2 (enrdf_load_stackoverflow) 1974-08-15

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