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US3224783A - Phonograph pickup construction for protecting phonograph records - Google Patents

Phonograph pickup construction for protecting phonograph records Download PDF

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Publication number
US3224783A
US3224783A US275749A US27574963A US3224783A US 3224783 A US3224783 A US 3224783A US 275749 A US275749 A US 275749A US 27574963 A US27574963 A US 27574963A US 3224783 A US3224783 A US 3224783A
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cartridge
record
needle
tone arm
bumper
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US275749A
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Alpha M Wiggins
John F Wood
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Euphonics Corp
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Euphonics Corp
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04RLOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00Piezoelectric transducers; Electrostrictive transducers
    • H04R17/04Gramophone pick-ups using a stylus; Recorders using a stylus
    • H04R17/08Gramophone pick-ups using a stylus; Recorders using a stylus signals being recorded or played back by vibration of a stylus in two orthogonal directions simultaneously

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  • FIG.1 A. M. WIGGINS ETAL PHONOGRAPH PICKUP CONSTRUCTION FOR PROTECTING PHONOGRAPH RECORDS Filed April 25, 1963 FIG.1
  • This invention concerns means built into a phonograph pickup, tone arm or cartridge to prevent damage to a phonograph record by mishandling of the tone arm or pickup.
  • a problem commonly encountered in the playing of a phonograph record with a stylus is the danger of accidentally damaging the modulation grooves of the record by mishandling the tone arm carrying the cartridge and stylus.
  • a common mistake is that of pressing down on the tone arm with excessive force. This results in pressures at the points of contact between the stylus and the record which are high enough to crush and permanently scratch or score the plastic material of the record. If a lateral motion is also accidentally applied to the tone arm simultaneously with the excessive downward fiorce, a lateral scratch running across the grooves will be scored into the record. These conditions result in permanent damage to the record.
  • Another object of the invention is to provide record portection means in which a bracket having hinged parts is used to mount a cartridge to a tone arm.
  • a further object is to provide a record protection means in which a phonograph cartridge has a clutch foot or a rotatable bumper cam for elevating the cartridge and stylus from a phonograph record to prevent damage to the record.
  • Still another object is to provide record protection means in which a cartridge carrying a needle structure is attached by a one-piece bracket or a two-part hinged bracket to a tone arm, and a bumper structure is to attached to the cartridge, bracket or needle structure that the cartridge, needle structure and a style carried thereby are rotated and raised up from the phonograph record when excessive force is applied to the tone arm while the record moves thereunder.
  • Another object is to provide a novel hinged bracket mounting for a phonograph cartridge with or without bumper means on the bracket to protect a phonograph record from damage.
  • FIG. 1 is a side elevational view on an enlarged scale of a pickup embodying the invention, part of a tone arm being shown in section, and part of a phonograph record being shown edgewise.
  • FIG. 2 is an end elevational view of the cartridge of FIG. 1.
  • FIG. 3 is a bottom plan view of the cartridge of FIGS. 1 and 2, but with the needle structure in reversed position.
  • FIG. 4 is an explored perspective view of parts of the bracket mounting of the cartridge.
  • FIG. 5 is a perspective View of a needle structure employed with the cartridge.
  • FIG. 6 is a side elevational view similar to FIG. 1 of another cartridge embodying another form of the invention.
  • FIG. 7 is an end view similar to FIG. 2 taken on line 7-7 of FIG. 6.
  • FIG. 7A is a perspective view of a screw type of bumper.
  • FIG. 7B is a bottom view similar to FIG. 3 of another cartridge.
  • FIG. 8 is a side elevational view of another cartridge embodying a further form of the invention.
  • FIG. 9 is a perspective view of a part of a bracket employed with the cartridge of FIG. 8.
  • FIG. 10 is a perspective view of a bumper boot employed with the bracket of FIGS. 8 and 9.
  • FIG. 11 is a view similar to FIG. 1 showing another form of the invention.
  • FIG. 12 is a sectional view taken on line 1212 of FIG. 11.
  • FIG. 13 is a perspective view of a bracket part employed with the cartridge of FIG. 11.
  • FIG. 14 is a view of another cartridge embodying another form of the invention, part of a tone arm being shown in section, and part of a record being shown edgewise.
  • FIG. 15 is a top plan view of the cartridge of FIG. 14.
  • FIG. 16 is a view similar to FIG. 14 but taken on the opposite side of the cartridge.
  • FIG. 17 is a view similar to FIG. 16 of another car tridge, with parts shown in a different operative position.
  • FIG. 18 is a fragmentary top plan view of the cartridge of FIG. 17, similar to a part of FIG. 15..
  • a pickup 10 including a transducer cartridge 20 having a turnover type of needle structure 22.
  • This needle structure has two needles 23a, 23b extending from arm 21 of a U-shaped frame 24 with a crossbar 25 connecting arms 21, 21.
  • the needles have oppositely directed styluses 32a, 32b.
  • Stylus 32a is a fine diamondtipped one for tracking microgroove long-playing monaural or stereophonic records.
  • Stylus 32b is a coarser jewel-tipped one for tracking wider-groove '78 rpm. records.
  • a handle 26 extends laterally outward of the cartridge casing 28 for turning over the needle structure.
  • the needle structure has its crossbar 25 engaged between projections 30 integral with the bottom of the casing.
  • the one-rnil stylus 32a extends downwardly from the casing as shown in FIGS. 1 and 2, and the handle 26 extends outwardly to the left as viewed in FIG. 2.
  • the handle is in the right lateral dotted line position of FIG. 2.
  • the coarser 3-rnil stylus 32b is then extended downwardly while stylus 32a extends upwardly into well 33 of the casing.
  • piezoelectric elements (not shown) connected to electrical contacts 29 at the rear of the casing 28, and mechanically coupled via yoke 31 to the needle structure 22. Electric wires W will be connected to contacts 29.
  • transducer cartridge and needle structure are known in the art.
  • a resilient rubber or plastic bumper or bumper foot 40 is provided on one side of handle 26, so that the bumper extends downwardly from the casing in one position of the needle structure when stylus 32a points downwardly. Since the needle structure in each of its positions is held fixed by spring 34 on the casing, the downwardly extending bumper 40 can be regarded as extending from the casing and as a fixed part of the cartridge. When the needle structure is turned over, to project stylus 32b downwardly, bumper 40 extends upwardly at the side of the casing as shown in dotted lines in FIG. 2. The bumper can be secured by an adhesive 41 to handle 26.
  • the cartridge 26 is provided with a mounting bracket 50 best shown in FIGS. 1, 2 and 4.
  • This bracket has a generally rectangular U-shaped plate part 52 formed with a deep longitudinal central notch 54.
  • a tongue 56 is struck up from the wide body of the plate and is provided with a tip 57 for engaging the looped end 58 of a coil spring 60.
  • Free ends 61a and 6111 are bent up angularly to the plane of the plate body. One of these ends can have an extension 62 for purposes to be described.
  • Two lateral notches 64 are formed at opposite edges of the plate 52 in arms 71 for engaging screws 65 used to secure the plate to bosses 66 at the underside of a tone arm 68; see FIG. 1.
  • Two further notches 70 are formed in the lateral edges of arms 71 of the plate adjacent to notches 64 at the bend lines L of plate ends 61a, 61b. These notches receive struck-up tabs 72 formed at opposite edges of a T-shaped bracket plate part 75.
  • the spring 60 can be adjustably tensioned by engaging any coil turn near the other end 59 of the spring, upon tip 76 of an upwardly bent tongue 77 extending outwardly of the end edge 79 at the wide end of plate 75.
  • plate part 52 When the two plates are engaged with each other, plate part 52 is secured in fixed relationship to the tone arm while the plate part 75 is hinged and pivotable with respect to the plate 52.
  • Tensioned spring 60 then holds the wide fiat plate portion 75a in abutment with narrow free ends 61a, 61b of plate 52.
  • a hook or bent tongue 78 is struck up from the narrow portion 75b of plate 75. The top of this hook engages on the upper side of plate end 52'.
  • the plate 75 is pivotable on transverse axis P having pivot points where tabs 72 engage at front edges of notches 70 as viewed in FIG. 1.
  • the plate 75 has a bent spring tongue 80 at its front end which engages in a notch 81 formed at the front end of casing 28.
  • Two downward-1y extending legs 83 at the rear end of the plate 75 engage lateral projections 84 of the casing 28.
  • the bracket plate 75 is thus detachably engaged with the casing 28.
  • the cartridge can pivot slightly in a clockwise direction with respect to the tone arm as viewed in FIG. 1.
  • the forward end normally assumes a lowermost position as the cartridge casing inclines downwardly from rear to front, so that one stylus or the other can follow a groove in phonograph record disk R.
  • one of the needles drives one or two piezoelectric elements (not shown) in the casing via yoke or saddle 31.
  • the bumper 40 extending downwardly from the cartridge will contact the moving record as the stylus end of the cartridge begins to retract into the tone arm.
  • the bumper contacts the record when the stylus 32a has retracted sufficiently.
  • the motion of the record further rotates the assembly of stylus, needle and cartridge about the pivot axis P and causes further retraction of the stylus end of the cartridge to the limit of travel of the bracket, leaving only the bumper in contact with the record.
  • the tension spring 60 rotates the cartridge back to the normal position of FIG. 1, thereby placing the stylus 32a in contact with the record and lifting the bumper 40 free from the record.
  • the bumper 40 is made of a sufiiciently soft, resilient material so that it cannot scratch or crush the plastic record material even if the tone arm is accidentally dropped from a considerable height to the record surface.
  • the broad bottom surface of the bumper etfectively absorbs the impact.
  • the bottom surface of the bumper rides frictionally over the record surface if the tone arm is moved forcefully laterally.
  • the retracting action is one of rotation of the cartridge and needle assembly by the application of a friction force parallel to and supplied by the record.
  • the rotation of the assembly is the action which raises the stylus free from the record.
  • the bumper 4% actually serves as a clutch foot or cam foot.
  • High compliance of the needle 23a is not required to effect record protection in this form of the invention, since a small downward pressure of the order of two grams will be sufficient to expand spring and bring the bumper and record in contact with each other. Thereafter the bumper and record cooperate to rotate the cartridge and needle structure away from the record while lifting the stylus out of and above the record grooves.
  • Bracket extension 62 can serve as an abutment to limit rotation of bracket part with respect to bracket part 52.
  • a ground wire W can be attached to the tip of the bracket extension 62 for conducting away static electric charge from the bracket.
  • FIGS. 6 and 7 is shown another form of the invention, simliar to that of FIGS. 1-4, and corresponding parts are identically numbered.
  • the cartridge 20a of pickup Na can be provided with the needle structure 22 of FIG. 5, but in this instance is shown assembled with a single needle 23.
  • the needle extends forwardly from a stationary projecting block 91 at the underside of the casing 28a. Needle 23 is engaged in yoke 31 and carries downwardly extending stylus 32 at its free end.
  • a single bumper or clutch foot 40a in the form of a screw or bolt made of resilient plastic material, is seated adjustably in a threaded hole 93 at the underside of the casing.
  • the screw has a rounded tip 401) with a square head Me which can be engaged by a wrench or other tool for adjusting the screw in hole 93.
  • the tip 40b is spherically curved and this tip projects downwardly toward the record surface S near stylus 32.
  • the two-part bracket 50 including hinged parts 52 and 75, may be employed to support the cartridge pivotally on a tone arm in the same manner as in FIG. 1.
  • FIGS. 6 and 7 operate in a manner similar to that of FIGS. 15.
  • the cartridge and needle are rotated around horizontal axis P and the stylus 32 is lifted clear of the record surface.
  • the needle need not be highly compliant for the purpose of protecting the record, since the mode of operation of the record protection assembly is substantially independent of needle compliance.
  • the screw bumper 40a is to be used instead of the bumper 40 on needle handle 26 of cartridge 20, the screw will be inserted in a screw hole 93 at the underside of the casing 28, as shown in FIG. 3.
  • a notch 26' will be provided in handle 26 to allow clearance for screw 40a; see FIG. 7B.
  • FIGS. 8-10 is shown another form of the invention in which cartridge 2% of pickup 10b may have the form of cartridge 20a, as illustrated, or could be of the form of cartridge 20 which carries a turnover needle structure.
  • the parts of the cartridge corresponding to those previously described in connection with cartridges 20 and 2011 are identically numbered.
  • the record protection arrangement of pickup 10b is S embodied in the bracket 50a.
  • the plate 75' of the bracket is modified from the bracket 75 of bracket 50 by provision of tab or foot 95 which extends downward perpendicularly to the plane of the plate from a lateral extension 96.
  • a bumper or clutch foot 40' which has an opening 97 in its upper end to receive foot 95.
  • the bottom of the bumper 40' is supported just above the record surface.
  • the spring 60 expands and permits the cartridge and needle to rotate and lift the stylus 32 clear of the record surface, as the moving record engages the bottom of the bumper.
  • FIGS. 8-10 The record protection arrangement of FIGS. 8-10 is similar to those of FIGS. 15 and 6, 7 in that the resilient bumper acts like a clutch or cam foot to rotate the cartridge and needle structure on the bottom of the bumper, which is in contact with the moving record surface, so that the stylus is lifted out of the record grooves and is held elevated above the record.
  • FIGS. 11-13 is shown another pickup arrangement for protecting the surface S of record R.
  • the arrangement of pickup may employ either cartridge 28 with the turnover needle structure 22 described in connection with FIGS. 1,, 2, 3 and or may employ the cartridge 2% with single needle 23 shown in FIG. 8.
  • Parts of the pickup in FIG. 11, corresponding to those of pickups previously described, are identically numbered.
  • the cartridge 20 is attached to tone arm 68a by means of hinged bracket 50b.
  • plate 75 is the same as previously described.
  • Plate 52a has a depending tab or leg 102 at its end 52 upon which fits a resilient bumper 40".
  • the bottom of this bumper is normally spaced slightly above the record surface S. It will be noted the bumper is stationary with respect to the plate 52a which is fixed in position with respect to the tone arm, while plate 75 is pivotable at axis P.
  • the whole assembly is substantially rigid when the stylus is in the record groove on surface 8.
  • the cartridge and the bracket part 75 to which it is attached rotate, with the stylus end rising relative to the tone arm while the stylus remains in the record groove.
  • the bumper 40" attached to the fixed bracket part 52a lands on the record surface S and prevents any further increase in force between the stylus and record groove.
  • the tension spring 60 is set so that five grams of force at the stylus relative to the tone arm is required to retract the cartridge, and suppose that the tone arm tracking force on the record is set at three grams. Thus if only two grams of additional force is applied to the tone arm, the cartridge will retract while in playing position.
  • the tension spring geometry is such that the retraction force remains quite constant over the full angle of retraction since the spring displacement or expansion per unit of retraction displacement force is very small.
  • the maximum downward force that can ever be applied by the stylus to the record groove is five grams, for the example stated. Any greater force is cushioned by the broad bottom of the resilient bumper 40".
  • the tracking and retraction forces can be determined at any desirable and practical magnitudes. While high compliance of the needles is not required for protection of the record against exessively applied force to the tone arm, it is desirable that the needles have sufficient vertical and lateral compliance to prevent damage to the record surface S if the pickup is moved laterally over the record with excessive downward pressure. Then if the tone arm is skidded or moved laterally across the record even with excessive downward force, the stylus will readily ride in and out over the grooves of the record without crushing the plastic record material and without scoring the groove walls.
  • the downward pressure will be borne by the bumper 40 which rides resiliently over the walls of the grooves. Since the bumper is made of resilient rubber or plastic material, its frictional contact with the record surface will tend to limit free lateral skidding of the pickup. Thus in the pickup the record surface will be protected whether the tone arm is accidentally dropped from a height to the record surface or is moved laterally over the record grooves with excessive downward force.
  • the pickup arrangement of FIG. 11 thus prevents damage to the record surface which might otherwise be caused by mishandling of the tone arm.
  • FIGS. 14, 15 and 16 is shown another form of the invention applied to pickup 10001.
  • the cartridge 200 is similar to that of cartridges 20a and 20b with a single needle 23.
  • a one-piece bracket 50 is employed to secure the cartridge in a fixed position with respect to tone arm 68b.
  • the bracket is secured by screws 65a engaged in slots 64' to a boss or bosses 66'.
  • Other parts of the bracket similar to those of bracket 50 previously described, are identically numbered.
  • Cartridge 200 is provided with a shaft which extends transversely through the casing 28'. This shaft carries a circularly curved sector plate 112 to which is secured a resilient rubber or plastic elongated cam or cam wheel 114.
  • Plate 112 has a radial extension arm 116 on which is a counterweight 118 which serves to hold the cam 114 rotated to its extreme clockwise position as shown in FIG. 14. In this position of the cam one edge 117 of plate 112, which extends beyond the cam 114, abuts a stationary stop pin 119 which projects laterally out of casing 28. The tone arm and cartridge then rest on stylus 32 which rides in a groove on the record surface S.
  • the cam is generally circularly curved and in registration with plate 112 at its forward end between points A and B, shown in FIGS. 14-16. Between point B and point C at the rear end of the cam, the cam gradually increases in radius with respect to shaft 110. The point B which is near point B is the lowermost point of the cam adjacent to record surface S. A forwardly located stop pin 12% is located above arm 116.
  • the arrangement of the cartridge on the tone arm is such that no relative motion can take place between these two members of the pickup.
  • the cam is sufficiently resilient so that it cannot scratch or score the record and has a substantial coeflicient of friction with the surface S of the record.
  • pickup 100i is similar to pickup 100a and corresponding parts are identically numbered.
  • the counterweight is omitted but in its place a counterspring 118a is employed to provide a counterfo-rce.
  • the spring is wound around shaft 110 and has one looped end 121 engaged on stop pin 119.
  • the other looped end 122 of the spring is engaged on a pin 125 fixed to plate 112 and extending laterally thereof between the plate and cartridge casing.
  • the record protection arrangement of pickup 10012 operates in the same manner as described for pickup 100a but has the advantage of a more compact construction and no heavy weight loading the stylus. In both the pickups 100a and 10012, the stylus is lifted clear of the record surface when the cam rotates upon frictional engagement with the moving record.
  • a phonograph pickup including a tone arm, transducer cartridge and needle carried by said cartridge, means for preventing damage to a phonograph record by said needle upon application of excessive force to the tone arm, comprising:
  • bracket having hinged parts, one part being engaged with the cartridge and pivotable with respect to the other part, said other part being adapted for mounting in a fixed position with respect to the tone arm,
  • spring means adjustable in tension connecting the hinged parts of the bracket for biasing the cartridge and needle outwardly of the tone arm so that the needle may contact the record
  • a resilient bumper carried by the pickup and disposed near the needle to engage the record upon application of said excessive force and to bear said force while the cartridge and needle pivot toward the tone arm, said bumper being in the form of a screw having a rounded tip, said cartridge having a threaded hole adjustably receiving said screw so that the rounded tip is adjustably positioned with respect to the needle.
  • a phonograph pickup including a tone arm, transducer cartridge and needle carried by said cartridge, means for preventing damage to a phonograph record by said needle upon application of excessive force to the tone arm, comprising:
  • counterforce means holding said bumper cam spaced from the record while the needle contacts the record, whereby upon application of said excessive force said bumper cam frictionally engages the record while the record m-oves so that the needle is raised clear of the record while the bumper cam bears said excessive force, said counterforce means being a counterweight secured to and extending outwardly of said bumper cam.
  • a phonograph pickup including a tone arm, transducer cartridge and a turnover needle structure having dual needles carried by the cartridge, means for preventing damage to a phonograph record by the needles upon application of excessive force to the tone arm, comprising:
  • a hinged bracket pivotally securing the cartridge to the tone arm
  • a resilient bumper in the form of a screw having a rounded head, said cartridge having a threaded hole adjustably receiving the screw, said'screw extending outwardly of the cartridge with said head located near said needle structure for contacting the record upon application of said excessive force to rotate the cartridge and needles away from the record toward the tone arm as the record moves with respect to the bumper while said bumper bears said excessive force.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Time Recorders, Dirve Recorders, Access Control (AREA)

Description

Dec. 21, 1965 A. M. WIGGINS ETAL PHONOGRAPH PICKUP CONSTRUCTION FOR PROTECTING PHONOGRAPH RECORDS Filed April 25, 1963 FIG.1
4 Sheets-Sheet 1 FIG. 3
INVENTORS 28 A.M.W|se|Ns BY J. F W o o 0 ATTORNEY De- 6 A. M. WIGGINS ETAL 3,224,783
PHONOGRAPH PICKUP CONSTRUCTION FOR PROTECTING PHONOGRAPH RECORDS Filed April 25, 1963 4 Sheets-Sheet 2 INVENTORS A. M. WIGGINS J. F. W000 ATTORNEY Dec. 1, 1965 A. M. WIGGINS ETAL 3,224,783
PHONOGRAPH PICKUP CONSTRUCTION FOR PROTECTING PHONOGRAPH RECORDS Filed April 25, 1963 4 Sheets-Sheet 4 FIG. I?
INVENTORS A. M. WIGGINS BY J. F. W000 ATTORNEY United States Patent 3,224,783 PHONOGRAPH PICKUP CONSTRUCTION FOR PROTECTING PHUNGGRAlPll-I RECORDS Alpha M. Wiggins and John F. Wood, San Juan, Puerto Rico, assignors to Euphonics Corporation, Guaynabo,
Puerto Rico, a corporation of Puerto Rico Filed Apr. 25, 1963, Ser. No. 275,749 3 Claims. (Cl. 27424) This invention concerns means built into a phonograph pickup, tone arm or cartridge to prevent damage to a phonograph record by mishandling of the tone arm or pickup.
A problem commonly encountered in the playing of a phonograph record with a stylus is the danger of accidentally damaging the modulation grooves of the record by mishandling the tone arm carrying the cartridge and stylus. A common mistake is that of pressing down on the tone arm with excessive force. This results in pressures at the points of contact between the stylus and the record which are high enough to crush and permanently scratch or score the plastic material of the record. If a lateral motion is also accidentally applied to the tone arm simultaneously with the excessive downward fiorce, a lateral scratch running across the grooves will be scored into the record. These conditions result in permanent damage to the record.
It is a principal object of the present invention to provide means built into the phonograph pickup which will substantially reduce or eliminate the danger of damage to the record by accidental mishandling of the tone arm and pickup.
It is one object of the invention to provide record protection means as described, wherein a bracket is employed to mount the cartridge to the tone arm, the bracket having hinged parts, and a bumper or bumper cam is attached to a part of the bracket, to the movable cartridge, or to a needle structure carried by the cartridge.
Another object of the invention is to provide record portection means in which a bracket having hinged parts is used to mount a cartridge to a tone arm.
A further object is to provide a record protection means in which a phonograph cartridge has a clutch foot or a rotatable bumper cam for elevating the cartridge and stylus from a phonograph record to prevent damage to the record.
Still another object is to provide record protection means in which a cartridge carrying a needle structure is attached by a one-piece bracket or a two-part hinged bracket to a tone arm, and a bumper structure is to attached to the cartridge, bracket or needle structure that the cartridge, needle structure and a style carried thereby are rotated and raised up from the phonograph record when excessive force is applied to the tone arm while the record moves thereunder.
Another object is to provide a novel hinged bracket mounting for a phonograph cartridge with or without bumper means on the bracket to protect a phonograph record from damage.
The invention will be best understood from the following description, taken together with the drawings, wherein:
FIG. 1 is a side elevational view on an enlarged scale of a pickup embodying the invention, part of a tone arm being shown in section, and part of a phonograph record being shown edgewise.
FIG. 2 is an end elevational view of the cartridge of FIG. 1.
FIG. 3 is a bottom plan view of the cartridge of FIGS. 1 and 2, but with the needle structure in reversed position.
3,224,783 Patented Dec. 21, 1965 FIG. 4 is an explored perspective view of parts of the bracket mounting of the cartridge.
FIG. 5 is a perspective View of a needle structure employed with the cartridge.
FIG. 6 is a side elevational view similar to FIG. 1 of another cartridge embodying another form of the invention.
FIG. 7 is an end view similar to FIG. 2 taken on line 7-7 of FIG. 6.
FIG. 7A is a perspective view of a screw type of bumper.
FIG. 7B is a bottom view similar to FIG. 3 of another cartridge.
FIG. 8 is a side elevational view of another cartridge embodying a further form of the invention.
FIG. 9 is a perspective view of a part of a bracket employed with the cartridge of FIG. 8.
FIG. 10 is a perspective view of a bumper boot employed with the bracket of FIGS. 8 and 9.
FIG. 11 is a view similar to FIG. 1 showing another form of the invention.
FIG. 12 is a sectional view taken on line 1212 of FIG. 11.
FIG. 13 is a perspective view of a bracket part employed with the cartridge of FIG. 11.
FIG. 14 is a view of another cartridge embodying another form of the invention, part of a tone arm being shown in section, and part of a record being shown edgewise.
FIG. 15 is a top plan view of the cartridge of FIG. 14.
FIG. 16 is a view similar to FIG. 14 but taken on the opposite side of the cartridge.
FIG. 17 is a view similar to FIG. 16 of another car tridge, with parts shown in a different operative position.
FIG. 18 is a fragmentary top plan view of the cartridge of FIG. 17, similar to a part of FIG. 15..
Referring first to FIGS. 1-5, the invention is shown embodied in a pickup 10 including a transducer cartridge 20 having a turnover type of needle structure 22. This needle structure has two needles 23a, 23b extending from arm 21 of a U-shaped frame 24 with a crossbar 25 connecting arms 21, 21. The needles have oppositely directed styluses 32a, 32b. Stylus 32a is a fine diamondtipped one for tracking microgroove long-playing monaural or stereophonic records. Stylus 32b is a coarser jewel-tipped one for tracking wider-groove '78 rpm. records. A handle 26 extends laterally outward of the cartridge casing 28 for turning over the needle structure. The needle structure has its crossbar 25 engaged between projections 30 integral with the bottom of the casing. In one position of the needle structure, the one-rnil stylus 32a extends downwardly from the casing as shown in FIGS. 1 and 2, and the handle 26 extends outwardly to the left as viewed in FIG. 2. In the other position of the needle structure, the handle is in the right lateral dotted line position of FIG. 2. The coarser 3-rnil stylus 32b is then extended downwardly while stylus 32a extends upwardly into well 33 of the casing.
In the cartridge are piezoelectric elements (not shown) connected to electrical contacts 29 at the rear of the casing 28, and mechanically coupled via yoke 31 to the needle structure 22. Electric wires W will be connected to contacts 29.
To the extent described, the transducer cartridge and needle structure are known in the art.
According to the present invention, a resilient rubber or plastic bumper or bumper foot 40 is provided on one side of handle 26, so that the bumper extends downwardly from the casing in one position of the needle structure when stylus 32a points downwardly. Since the needle structure in each of its positions is held fixed by spring 34 on the casing, the downwardly extending bumper 40 can be regarded as extending from the casing and as a fixed part of the cartridge. When the needle structure is turned over, to project stylus 32b downwardly, bumper 40 extends upwardly at the side of the casing as shown in dotted lines in FIG. 2. The bumper can be secured by an adhesive 41 to handle 26.
The cartridge 26 is provided with a mounting bracket 50 best shown in FIGS. 1, 2 and 4. This bracket has a generally rectangular U-shaped plate part 52 formed with a deep longitudinal central notch 54. A tongue 56 is struck up from the wide body of the plate and is provided with a tip 57 for engaging the looped end 58 of a coil spring 60. Free ends 61a and 6111 are bent up angularly to the plane of the plate body. One of these ends can have an extension 62 for purposes to be described.
Two lateral notches 64 are formed at opposite edges of the plate 52 in arms 71 for engaging screws 65 used to secure the plate to bosses 66 at the underside of a tone arm 68; see FIG. 1. Two further notches 70 are formed in the lateral edges of arms 71 of the plate adjacent to notches 64 at the bend lines L of plate ends 61a, 61b. These notches receive struck-up tabs 72 formed at opposite edges of a T-shaped bracket plate part 75. The spring 60 can be adjustably tensioned by engaging any coil turn near the other end 59 of the spring, upon tip 76 of an upwardly bent tongue 77 extending outwardly of the end edge 79 at the wide end of plate 75. When the two plates are engaged with each other, plate part 52 is secured in fixed relationship to the tone arm while the plate part 75 is hinged and pivotable with respect to the plate 52. Tensioned spring 60 then holds the wide fiat plate portion 75a in abutment with narrow free ends 61a, 61b of plate 52. A hook or bent tongue 78 is struck up from the narrow portion 75b of plate 75. The top of this hook engages on the upper side of plate end 52'. The plate 75 is pivotable on transverse axis P having pivot points where tabs 72 engage at front edges of notches 70 as viewed in FIG. 1.
The plate 75 has a bent spring tongue 80 at its front end which engages in a notch 81 formed at the front end of casing 28. Two downward-1y extending legs 83 at the rear end of the plate 75 engage lateral projections 84 of the casing 28. The bracket plate 75 is thus detachably engaged with the casing 28. The cartridge can pivot slightly in a clockwise direction with respect to the tone arm as viewed in FIG. 1. The forward end normally assumes a lowermost position as the cartridge casing inclines downwardly from rear to front, so that one stylus or the other can follow a groove in phonograph record disk R.
During normal operation of the assembly of FIGS. 13, one of the needles drives one or two piezoelectric elements (not shown) in the casing via yoke or saddle 31. Suppose excessive force is applied downwardly on the tone arm while record R is rotating. The bumper 40 extending downwardly from the cartridge will contact the moving record as the stylus end of the cartridge begins to retract into the tone arm. The bumper contacts the record when the stylus 32a has retracted sufficiently. Then the motion of the record further rotates the assembly of stylus, needle and cartridge about the pivot axis P and causes further retraction of the stylus end of the cartridge to the limit of travel of the bracket, leaving only the bumper in contact with the record.
If the tone arm is moved laterally across the moving record, or if additional downward force is applied, no damage can be done to the record surface since only the bumper is contacting the record. When the excess downward force is removed from the tone arm, the tension spring 60 rotates the cartridge back to the normal position of FIG. 1, thereby placing the stylus 32a in contact with the record and lifting the bumper 40 free from the record.
The bumper 40 is made of a sufiiciently soft, resilient material so that it cannot scratch or crush the plastic record material even if the tone arm is accidentally dropped from a considerable height to the record surface. The broad bottom surface of the bumper etfectively absorbs the impact. The bottom surface of the bumper rides frictionally over the record surface if the tone arm is moved forcefully laterally.
It should be noted that in this form of the invention the retracting action is one of rotation of the cartridge and needle assembly by the application of a friction force parallel to and supplied by the record. The rotation of the assembly is the action which raises the stylus free from the record. Thus the bumper 4% actually serves as a clutch foot or cam foot.
High compliance of the needle 23a is not required to effect record protection in this form of the invention, since a small downward pressure of the order of two grams will be sufficient to expand spring and bring the bumper and record in contact with each other. Thereafter the bumper and record cooperate to rotate the cartridge and needle structure away from the record while lifting the stylus out of and above the record grooves.
Bracket extension 62 can serve as an abutment to limit rotation of bracket part with respect to bracket part 52. In addition, a ground wire W, indicated schematically in FIG. 4, can be attached to the tip of the bracket extension 62 for conducting away static electric charge from the bracket.
In FIGS. 6 and 7 is shown another form of the invention, simliar to that of FIGS. 1-4, and corresponding parts are identically numbered. The cartridge 20a of pickup Na can be provided with the needle structure 22 of FIG. 5, but in this instance is shown assembled with a single needle 23. The needle extends forwardly from a stationary projecting block 91 at the underside of the casing 28a. Needle 23 is engaged in yoke 31 and carries downwardly extending stylus 32 at its free end. A single bumper or clutch foot 40a, in the form of a screw or bolt made of resilient plastic material, is seated adjustably in a threaded hole 93 at the underside of the casing. The screw has a rounded tip 401) with a square head Me which can be engaged by a wrench or other tool for adjusting the screw in hole 93. The tip 40b is spherically curved and this tip projects downwardly toward the record surface S near stylus 32.
The two-part bracket 50, including hinged parts 52 and 75, may be employed to support the cartridge pivotally on a tone arm in the same manner as in FIG. 1.
The record protection arrangement of FIGS. 6 and 7 operates in a manner similar to that of FIGS. 15. When the rounded tip 4% of bumper 40a contacts record surface S upon application of an excessive downward force upon the tone arm and cartridge, the cartridge and needle are rotated around horizontal axis P and the stylus 32 is lifted clear of the record surface. In this form of the invention, as in that of cartridge 20, the needle need not be highly compliant for the purpose of protecting the record, since the mode of operation of the record protection assembly is substantially independent of needle compliance.
If the screw bumper 40a is to be used instead of the bumper 40 on needle handle 26 of cartridge 20, the screw will be inserted in a screw hole 93 at the underside of the casing 28, as shown in FIG. 3. A notch 26' will be provided in handle 26 to allow clearance for screw 40a; see FIG. 7B.
In FIGS. 8-10 is shown another form of the invention in which cartridge 2% of pickup 10b may have the form of cartridge 20a, as illustrated, or could be of the form of cartridge 20 which carries a turnover needle structure. The parts of the cartridge corresponding to those previously described in connection with cartridges 20 and 2011 are identically numbered.
The record protection arrangement of pickup 10b is S embodied in the bracket 50a. The plate 75' of the bracket is modified from the bracket 75 of bracket 50 by provision of tab or foot 95 which extends downward perpendicularly to the plane of the plate from a lateral extension 96. Upon the tab is engaged a bumper or clutch foot 40' which has an opening 97 in its upper end to receive foot 95.
When the stylus 32 rides on record surface S, the bottom of the bumper 40' is supported just above the record surface. When an excessive force is applied to the tone arm carrying the cartridge, the spring 60 expands and permits the cartridge and needle to rotate and lift the stylus 32 clear of the record surface, as the moving record engages the bottom of the bumper.
It will be noted that the bumper is carried by the pivotal plate part 75 of the bracket while the other plate part 52 will remain fixed to the tone arm. The record protection arrangement of FIGS. 8-10 is similar to those of FIGS. 15 and 6, 7 in that the resilient bumper acts like a clutch or cam foot to rotate the cartridge and needle structure on the bottom of the bumper, which is in contact with the moving record surface, so that the stylus is lifted out of the record grooves and is held elevated above the record.
In FIGS. 11-13 is shown another pickup arrangement for protecting the surface S of record R. The arrangement of pickup may employ either cartridge 28 with the turnover needle structure 22 described in connection with FIGS. 1,, 2, 3 and or may employ the cartridge 2% with single needle 23 shown in FIG. 8. Parts of the pickup in FIG. 11, corresponding to those of pickups previously described, are identically numbered.
In the pickup of FIG. 11, the cartridge 20 is attached to tone arm 68a by means of hinged bracket 50b. In this bracket, plate 75 is the same as previously described. Plate 52a has a depending tab or leg 102 at its end 52 upon which fits a resilient bumper 40". The bottom of this bumper is normally spaced slightly above the record surface S. It will be noted the bumper is stationary with respect to the plate 52a which is fixed in position with respect to the tone arm, while plate 75 is pivotable at axis P. The whole assembly is substantially rigid when the stylus is in the record groove on surface 8.
When an excessive downward force is applied to the tone arm, the cartridge and the bracket part 75 to which it is attached rotate, with the stylus end rising relative to the tone arm while the stylus remains in the record groove. When the stylus end of the cartridge has retracted sufficiently, the bumper 40" attached to the fixed bracket part 52a lands on the record surface S and prevents any further increase in force between the stylus and record groove.
Suppose the tension spring 60 is set so that five grams of force at the stylus relative to the tone arm is required to retract the cartridge, and suppose that the tone arm tracking force on the record is set at three grams. Thus if only two grams of additional force is applied to the tone arm, the cartridge will retract while in playing position. The tension spring geometry is such that the retraction force remains quite constant over the full angle of retraction since the spring displacement or expansion per unit of retraction displacement force is very small.
In this arrangement of the pickup, the maximum downward force that can ever be applied by the stylus to the record groove is five grams, for the example stated. Any greater force is cushioned by the broad bottom of the resilient bumper 40". The tracking and retraction forces can be determined at any desirable and practical magnitudes. While high compliance of the needles is not required for protection of the record against exessively applied force to the tone arm, it is desirable that the needles have sufficient vertical and lateral compliance to prevent damage to the record surface S if the pickup is moved laterally over the record with excessive downward pressure. Then if the tone arm is skidded or moved laterally across the record even with excessive downward force, the stylus will readily ride in and out over the grooves of the record without crushing the plastic record material and without scoring the groove walls. The downward pressure will be borne by the bumper 40 which rides resiliently over the walls of the grooves. Since the bumper is made of resilient rubber or plastic material, its frictional contact with the record surface will tend to limit free lateral skidding of the pickup. Thus in the pickup the record surface will be protected whether the tone arm is accidentally dropped from a height to the record surface or is moved laterally over the record grooves with excessive downward force. The pickup arrangement of FIG. 11 thus prevents damage to the record surface which might otherwise be caused by mishandling of the tone arm.
In FIGS. 14, 15 and 16 is shown another form of the invention applied to pickup 10001. The cartridge 200 is similar to that of cartridges 20a and 20b with a single needle 23. A one-piece bracket 50 is employed to secure the cartridge in a fixed position with respect to tone arm 68b. The bracket is secured by screws 65a engaged in slots 64' to a boss or bosses 66'. Other parts of the bracket, similar to those of bracket 50 previously described, are identically numbered. Cartridge 200 is provided with a shaft which extends transversely through the casing 28'. This shaft carries a circularly curved sector plate 112 to which is secured a resilient rubber or plastic elongated cam or cam wheel 114. Plate 112 has a radial extension arm 116 on which is a counterweight 118 which serves to hold the cam 114 rotated to its extreme clockwise position as shown in FIG. 14. In this position of the cam one edge 117 of plate 112, which extends beyond the cam 114, abuts a stationary stop pin 119 which projects laterally out of casing 28. The tone arm and cartridge then rest on stylus 32 which rides in a groove on the record surface S.
The cam is generally circularly curved and in registration with plate 112 at its forward end between points A and B, shown in FIGS. 14-16. Between point B and point C at the rear end of the cam, the cam gradually increases in radius with respect to shaft 110. The point B which is near point B is the lowermost point of the cam adjacent to record surface S. A forwardly located stop pin 12% is located above arm 116.
The arrangement of the cartridge on the tone arm is such that no relative motion can take place between these two members of the pickup. The cam is sufficiently resilient so that it cannot scratch or score the record and has a substantial coeflicient of friction with the surface S of the record.
When an excessive downward force is applied to the tone arm, the needle 23, which should have high vertical compliance, retracts toward the casing of the cartridge until the cam 1114 comes in contact with the record surface. When the cam touches the moving surface of the record, a force parallel to the record surface, and due to the record movement, is produced. This force rotates the cam forwardly counterclockwise on the record R as viewed in FIG. 14 and clockwise as viewed in FIG. 16. The cam is stopped when arm 116 encounters stop pin 120. Due to the elongated shape of the cam, this rotation of the cam elevates the entire pickup, including tone arm and cartridge as indicated in FIG. 16, thereby lifting the stylus 32 out of the record groove and free from the record. Further excessive downward force or lateral movement of the pickup will not damage the record. When the excessive downward force is removed, the cam returns to its original retracted position of FIG. 14, as the torque of the counterweight 11 3 provides a counterforce to overcome the torque produced by friction of the cam against the moving record. The stylus then returns to its normal position in the record groove.
In FIGS. 17 and 18, pickup 100i) is similar to pickup 100a and corresponding parts are identically numbered. The counterweight is omitted but in its place a counterspring 118a is employed to provide a counterfo-rce. The spring is wound around shaft 110 and has one looped end 121 engaged on stop pin 119. The other looped end 122 of the spring is engaged on a pin 125 fixed to plate 112 and extending laterally thereof between the plate and cartridge casing. The record protection arrangement of pickup 10012 operates in the same manner as described for pickup 100a but has the advantage of a more compact construction and no heavy weight loading the stylus. In both the pickups 100a and 10012, the stylus is lifted clear of the record surface when the cam rotates upon frictional engagement with the moving record. Arm 116 engages stop pin 120 to stop the rotation of the cam. To this extent the record protection arrangements of pickups 100a and 100i) resemble those of pickups 10, 119a and 10!). However, in the latter pickups the cartridge rotates as the bumper contacts the moving record while the stylus is lifted clear of the record. In pickups 100a and 10% the tone arm rises along with the cartridge and stylus.
Although a limited number of embodiments of the invention have been described, it will be understood that many variations can be made without departing from the invention.
What is claimed and sought to be protected by Letters Patent is:
1. In a phonograph pickup including a tone arm, transducer cartridge and needle carried by said cartridge, means for preventing damage to a phonograph record by said needle upon application of excessive force to the tone arm, comprising:
a bracket having hinged parts, one part being engaged with the cartridge and pivotable with respect to the other part, said other part being adapted for mounting in a fixed position with respect to the tone arm,
spring means adjustable in tension connecting the hinged parts of the bracket for biasing the cartridge and needle outwardly of the tone arm so that the needle may contact the record, and
a resilient bumper carried by the pickup and disposed near the needle to engage the record upon application of said excessive force and to bear said force while the cartridge and needle pivot toward the tone arm, said bumper being in the form of a screw having a rounded tip, said cartridge having a threaded hole adjustably receiving said screw so that the rounded tip is adjustably positioned with respect to the needle.
2. In a phonograph pickup including a tone arm, transducer cartridge and needle carried by said cartridge, means for preventing damage to a phonograph record by said needle upon application of excessive force to the tone arm, comprising:
a resilient bumper cam,
means rotatably mounting said bumper cam near the needle, and
counterforce means holding said bumper cam spaced from the record while the needle contacts the record, whereby upon application of said excessive force said bumper cam frictionally engages the record while the record m-oves so that the needle is raised clear of the record while the bumper cam bears said excessive force, said counterforce means being a counterweight secured to and extending outwardly of said bumper cam.
3. In a phonograph pickup including a tone arm, transducer cartridge and a turnover needle structure having dual needles carried by the cartridge, means for preventing damage to a phonograph record by the needles upon application of excessive force to the tone arm, comprising:
a hinged bracket pivotally securing the cartridge to the tone arm,
spring means biasing the cartridge and needle outwardly of the tone arm so that one of the needles contacts the phonograph record in each position of said needle structure, and
a resilient bumper in the form of a screw having a rounded head, said cartridge having a threaded hole adjustably receiving the screw, said'screw extending outwardly of the cartridge with said head located near said needle structure for contacting the record upon application of said excessive force to rotate the cartridge and needles away from the record toward the tone arm as the record moves with respect to the bumper while said bumper bears said excessive force.
References Cited by the Examiner UNITED STATES PATENTS 2,582,948 1/1952 Cairnes 274-23 3,074,726 1/1963 Sioles et a1 274-24 3,173,692 3/1965 Van Antwerp 27423 NORTON ANSHER, Primary Examiner.
CLIFFORD PRICE, Assistant Examiner.

Claims (1)

1. IN A PHONOGRAPH PICKUP INCLUDING A TONE ARM, TRANSDUCER CARTRIDGE AND NEEDLE CARRIED BY SAID CARTRIDGE, MEANS FOR PREVENTING DAMAGE TO A PHONOGRAPH RECORD BY SAID NEEDLE UPON APPLICATION OF EXCESSIVE FORCE TO THE TONE ARM, COMPRISING: A BRACKET HAVING HINGED PARTS, ONE PART BEING ENGAGED WITH THE CARTRIDGE AND PIVOTABLE WITH RESPECT TO THE OTHER PART, SAID PART BEING ADAPTED FOR MOUNTING IN A FIXED POSITION WITH RESPECT TO THE TONE ARM, SPRING MEANS ADJUSTABLE IN TENSION CONNECTING THE HINGED PARTS OF THE BRACKET FOR BIASING THE CARTRIDGE AND NEEDLE OUTWARDLY OF THE TONE ARM SO THAT THE NEEDLE MAY CONTACT THE RECORD, AND A RESILIENT BUMPER CARRIED BY THE PICKUP AND DISPOSED NEAR THE NEEDLE TO ENGAGE THE RECORD UPON APPLICATION OF SAID EXCESSIVE FORCE AND TO BEAR SAID FORCE WHILE THE CARTRIDGE AND NEEDLE PIVOT TOWARD THE TONE ARM, SAID BUMPER BEING IN THE FORM OF A SCREW HAVING A ROUNDED TIP, SAID CARTRIDGE HAVING A THREADED HOLE ADJUSTABLY RECEIVING SAID SCREW SO THAT THE ROUNDED TIP IS ADJUSTABLY POSITIONED WITH RESPECT TO THE NEEDLE.
US275749A 1963-04-25 1963-04-25 Phonograph pickup construction for protecting phonograph records Expired - Lifetime US3224783A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3328038A (en) * 1964-04-02 1967-06-27 Gen Electric Cartridge arrangement
US3445118A (en) * 1967-03-31 1969-05-20 Bsr Ltd Cartridge holder for the pick-up arm of a record player
US3475032A (en) * 1966-04-13 1969-10-28 Sonotone Corp Phonograph cartridge retraction means

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2582948A (en) * 1947-05-06 1952-01-22 Motorola Inc Phonograph pickup unit
US3074726A (en) * 1960-07-19 1963-01-22 Zenith Radio Corp Tone arm and cartridge assembly
US3173692A (en) * 1962-02-19 1965-03-16 Vm Corp Phonograph tone arm

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2582948A (en) * 1947-05-06 1952-01-22 Motorola Inc Phonograph pickup unit
US3074726A (en) * 1960-07-19 1963-01-22 Zenith Radio Corp Tone arm and cartridge assembly
US3173692A (en) * 1962-02-19 1965-03-16 Vm Corp Phonograph tone arm

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3328038A (en) * 1964-04-02 1967-06-27 Gen Electric Cartridge arrangement
US3475032A (en) * 1966-04-13 1969-10-28 Sonotone Corp Phonograph cartridge retraction means
US3445118A (en) * 1967-03-31 1969-05-20 Bsr Ltd Cartridge holder for the pick-up arm of a record player

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