US1734454A - Electric phonograph reproducer - Google Patents

Description

Nov. 5, 1929. A. A. THOMAS ELECTRIC PHONOGRAPH REPRODUCER Filed Jan- 28, 1928 INVENTOR Patented Nov. 5, 1929 anorrn A. moms, or NEW relax, N. Y.

ELECTRIC PHONOGRAPH REPRODUCER Application filed January 28, 1928. Serial No. 250,100.

This invention relates to electric phonograph reproducers popularly known as pickups, and its object is to provide a reproducer capable of selectively playing lateral-cut records and vertical-cut records without adjustment of the reproducer casing on its supporting arm. The electric pickup of my invention has two different stylus members for playing different types of records. These members are preferably arranged side-by-side, so that either is readily placed in playing contact with a'record without the need of changing the position of the reproducer on its arm. In other words, my new electric pickup is always in condition to play lateral-cut records or vertical-cut records, as desired. The vibrations of each stylus member are converted into electric impulses. For playing lateral-cut records of the Victor type, I use a pivoted needle arm, and for vertical-cut records of the Edison type I use a diamond point or like stylus mounted permanently in a vertically movable holder. Neither stylus interferes with the operation of the other.

The various features and practical advantages of my invention will be clearly understood from a detailed description of the accompanying drawings, in which I have illustrated several embodiments of my double-acting pickup.

In these drawings Fig. 1 is a sectional view of an electric phonograph reproducer constructed in accordance with my invention, this section being approximately on line 11 of Fig. 2, and showing the instrument in position to play vertical-cut records;

Fig. 2 represents a sectional view on line 22 of Fig. 1, showing the device in position to play lateral-cut records through a pivoted needle arm;

Fig. 3 is a fragmentary detail view on sec tion line 33 of Fig. 2, to show a novel form of pivot mounting for the needle arm;

Fig. 4 illustrates in section a modified con struction in which the reproducer casing is adjustable on its supporting arm to bring either stylus member into playing position, this view showing the instrument playing a lateral-cut record; and

Fig. 5 is a diagrammatic view of a modification having a diiferent magnetic field systern from that embodied in Figs. 1, 2 and 4.

Before I begin a detailed description of the drawings, I want to explain that I have purposely exaggerated the dimensions and relative proportions of the parts in order to make the views as clear as possible and easy to read. The actual instrument can be made considerably more compact than the illustrations, which are therefore not to be taken as shop drawings made to accurate scale.

In Figs. 1 and 2, there is a casing of rectangular box-like shape, in which the side 12 may be formed integral with the body. The other side of the casing is formed by a removable cover plate 13 held in place by screws 14 or otherwise. The-casing 10 can be made of stamped sheet metal, of cast aluminum, of molded composition material such as bakelite, or in any other practical way. The rear end of casing 10 is provided with a hub 15 by means of which the instrument is mounted on a supporting arm adapted toswing over a record, as will be understood without additional illustration.

Inside the casing is mounted a field magnet system, which in the present instance comprises a pair of permanent magnets M and M. These magnets can be stamped or punched from sheet steel, either solid or laminated. Cobalt steel or silicon steel makes excellent permanent magnets. The wall 12 of casing 10 is formed with lugs or bosses 16 to which the magnets are rigidly secured by screws 17 or otherwise. The magnet M has oppositely extending polar projections 18 and 19, and the magnet M has similar projections or arms 18 and 19'. The polar arms 19 and 19 are bent laterally at 20 and 20' to project horizontally, while the polar arms 18 and 18 extend downwardly. The reason for this right-angled relation of the pole pieces 18.18' and 2020 will presently be explained. The polar arms 18 and 19 of magnet M are formed with lateral extensions 21 and 22, and the polar arms 18 and 19 of magnet M have similar extensions 21 and 22. Each pair of aligned lateral extenslons 2l21 and 2222 is separated by an ail-gap 23 of predetermined reluctance. On each pair of these lateral extensions is mounted a coil 24.. Only one coil need be used, but it is better to employ two coils in series. The circuit conductors 25 for the coils are conveniently led through the hub 15 of the casing. It is clear from Fig. 1 that the coils 24 are mounted on magnetic shunt paths through which the field flux passes in series.

Tn the upper part of casing 10 is mounted a vibratory armature 26, which is here shown as an elastic magnetic strip or band secured at its ends by screws 27 to lugs 28 of the easing. Tn order to produce a constant state of tension in the armature strip 26, the lugs 28 are formed with projecting edges 29 over which the armature band 26 passes and between which it is held stretched for vibratory movement. The armature band 26 is separated from the lateral pole pieces 20 and 20 by two airgaps 30 across which the field flux passes in series. As seen in Fig. 2, the plane of armature 26 is substantially parallel with the plane of the polar faces of pole pieces 20 and 20.

At the bottom of casing 10 is mounted a second armature 31, which is preferably a duplicate o1 armature 26 and is mounted in the same way on projections 32 by screws 33. In other words, the elastic armature band 31 is held stretched or tensioned between the rounded projections 32 for vibratory movement in a vertical direction toward and from the pole pieces 18 and 18, from which it is separated by airgaps 34. A stylus holder 35 is rigidly connected to the center of armature 31, as by a rivet 36 or otherwise. In the present instance, the stylus member 35 carries a stylus point 37 adapted to play vertical-cut records of the Edison type. A crosssectional fragment of one of these records is shown at 38 in Fig. 1. For'playing verticale cut records of the Pathe type, in which the grooves are very much wider than in the Edison records, the stylus 37 would be a sapphire ball, or other practical form of reproducing element. The bottom of casing 10 has a hole 39 through which the stylus member 35 projects.

The armature band 26 is actuated by a lever or needle arm 40 pivoted to the lower end of casing 10. Fig. 3 illustrates a simple and eficient arrangement for mounting the needle arm 40. Two right-angelcd plates 41 are connected to the bottom of the casing by fastening members 42, which may be screws. bolts, rivets and the like. The upper end of plates 41 are bent over to form bearing lugs 13 for pointed screws 44, between which the needle arm40 is pivoted for lateral movement. The plates 41 can be shaped from a strip of brass and the screws 44 pass through aligned screw holes out in the bent-over lugs 43 and the main section of the plates. In this Way each screw is firmly mounted in a pair of spaced bearings. Since the bent-over lugs 43 are slightly resilient, they can be so adjusted that the screw-holes in them are very slightly out of alignment with the inner pair of screw-holes. When the bearing screws 44 are then inserted into the slightly disaligned screw-holes, the resilient overhanging lugs 43 are placed under spring tension and hold the screws firmly in adjusted position, so that they cannot work loose during the vibrations of needle arm 40. This simple mounting allows the needle arm to vibrate with practically no lost motion. The lower portion of the needle arm is in the form of a tubular holder 45, which projects through an opening 46 in the bottom of casing 10 and is adapted to receive a needle 47, or other stylus for playing lateral-cut records. The needles are connected to the holder 45 by a set-screw 48 which extends through a. slot 49 in the cover plate 13 of the casing. The inner end of needle arm 40 terminates in a lateral projection 50, which is attached to the center of the armature 26, as by a rivet or in any other practical way.

The operation of the double-acting pickup above described will be clearly understood from the foregoing description, and T shall therefore explain it as briefly as possible. Looking at Fig. 1, which shows the instrument in position to play vertical-cut records, it is clear that, as the stylus member 35 vibrates'up and down toward and from the pole pieces 18 and 1 .'the field flux of the series magnets M and M is varied across the airgaps 34 and through the vibratory armature 31. The changes in the reluctance of the path including the variable airgaps 34 causes corresponding variations in the density of the magnetic flux passing through the shunt cores 2'l-21 and 2222'. These flux variations through the coils 24 generate current impulses in the circuit of the coils. which are supposed to be properly connected in an amplifying system for controlling or operating suitable loudspeaker mechanism. I need notshow or describe such a system. because phonographic amplifying and reproducing circuits are well known in the phonograph and radio arts. To play lateral-cut records, it is only necessary to place the point of needle 47 in the record groove without making any adjustment of the reproduccr casing on its supporting arm. Referring to Fig. 2. as the pivoted needle arm 40 vibrates laterally, the tensioned' armature strip 26 moves toward and from the pole pieces 20 and 20, thereby varying the air-gaps 30 and producing corresponding current impulses in coils 24, as explained in connection with the operation of armature 31.

Attention is called to the fact that neither stylus member interferes with the operation of the other. Vhcn the stylus member 35 is in playing position, the projecting needle holder 45 is not in the way, because the bottom edge'45' of the holder is considerably above the playing stylus 37 It is here assumed that no needle is in the holder 45, this being the only precaution that the operator has to take. When playing lateral-cut records as shown in Fig. 2, the idle stylus 37 is above the record 51 and is therefore out of the way. This double-acting reproducer is as easy and simple to use as a single-acting pickup capable of playing only one kind of record. It goes without saying that the stylus members are arranged at the proper playing angle, according to the usual practice. The vertical position of the stylus members in the drawings is intended only for illustrative purposes.

The combined reluctance of the two shunt airgaps 23 should preferably be about equal to the combined normal reluctance of the two pairs of armature air-gaps 30 and 34', so that normally the field flux divides about evenly between the shunt paths through the coils and the main path through the armatures 26 and 31. I mention this merely as a suggestion, and in no sense as a limitation of my invention. In fact, the shunt paths 21-21 and 2222 can be omitted and the coils 24 directly mounted on one or more of the polar arms 1819 and 18-19 of the field magnets.

In the particular field magnet system shown in Figs. 1 and 2, the flux always passes through the armatures 26 and 31 and the associated airgaps in series, irrespective of which armature is operating. There is no objection to the variable field flux passing also through the idle armature, even if the latter should tend to vibrate slightly. Such tendency, if it should exist in any particular design, would be negligible.

The modification shown in Fig. 4 differs from the construction in Figs. 1 and 2 in one particular onlyna-mely, the needle arm 40 is a bellcrank or right-angled lever pivoted at its apex 44 and having a needle holder 45 projecting through a hole 52 in the cover plate 13 of casing 10. Since the needle holder 45 in Fig. 4 is at right angles to the stylus member 35, the casing 10 must be turned on its supporting arm through an arc of about ninety degrees to bring either stylus into playing position. :On this account the modification of Fig. 4 is not so convenient to use as the preferred form of Figs. 1 and 2, but it is nevertheless a practical construction within the scope of my invention. Since all the other parts shown in Fig. 4 are the same as those described in detail in Figs. 1 and 2, it will not be necessary to say anything more about Fig. 4. I have used the same reference numerals in Fig. 4 as in Figs. 1 and 2 to indicate like parts. What was said about the operation of the instrument shown in Figs. 1 and 2, is fully applicable to the modification of Fig. 4 without the need of repetition.

Fig. 5 represents diagrammatically a slightly difierent form of field magnet system, in which a single magnet structure provides two parallel fields. The field structure here shown consists of a magnetic body M having limbs 53 and 54 connected by a crosspiece 55. The limb 53 terminates in pole pieces 56 and 57 and the limb 54 is similarly provided with pole pieces 56 and 57'. The pole pieces 56 and 57 are of one polarity (marked N for distinction), and the pole pieces 56 and 57 are of the other'polarity (both marked by S). We thus have in efiect two magnets in parallel, which may be considered as divided by the imaginary line 58. One or more of the pole pieces carry coils, of which two pairs 59 and 59 are shown in Fig. 5. When the armature 21 is vibrated by the stylus member 35 playing vertical-cut records, the field flux is varied through the pole pieces 56 and 56', thereby generating current impulses in the associated coil or coils 59. The flux variations through pole pieces 5656 and the vibratory armature 21 do not appreciably affect the normal flux through pole pieces 57-57 and the idle armature 26, since the two pairs of pole pieces and their associated armatures are in parallel magnetic paths,,which are to some extent independent of each other. WVhen the armature 26 of Fig. 5 is-vibrated by the needle arm 40 or 40' in playing lateral-cut records, the field flux is varied through the pole pieces 57 and 57 so that current impulses are induced in the coil or coils 59. The coils 59 and 59 may be connected in parallel in the same amplifying circuit, or they may be connected in circuit only when the associated armature is in operative condition. It is clear that the field magnet system of Fig. 5 can be substituted in Figs. 1, 2 and 4, without making any other changes.

When I speak of the reproducer as being capable of playing both kinds of records without adjustment of the unit on its support, I do not refer to the movement of the reproducer easing into and out of operative position, for every phonograph pickup must be so mounted as to be movable away from the record table. What I mean is as will be clear from the preceding description, that either stylus can be brought into playing position without special adjustment of the unit: In other words, the reproducer is manipulated in the same Way for playing either kind of record. In some of the claims I refor to the stylus members as being mounted in fixed relation on the casing. This does not mean, of course, that the two styli carried by (or formingpart of) those members are inseparable therefrom. As is well known, the needles used for lateral-cut records are removable because they wear out at the point, but the stylus for playing Edison records may be permanently embedded in its holder.

The fixed relation of the stylus members means that they need not be adjusted into difierent positions on the casing for playing difierent kinds of records, and this holds true whether the casing as a whole is adjustable on its supporting arm or is mounted thereon in fixed position.

Although I have shown and described certain specific constructions, I want it clearly understood that my invention is not limited to any of the details set forth, unless specified in the claims. As far as I know, I am the first to devise an electric phonograph reproducer adapted to selectively play vertical-cut records and lateral-cut records without adjusting the reproducer casing on its supporting arm, and so I claim this idea in a fundamental way. The basic principle of my invention may be carried out in various other constructions without departing from the scope of the invention as defined in the appended claims.

I claim as my invention:

1. In phonographic reproducing mechanism, an arm supported to swing over a rec- 0rd, and an electric reproducing unit mounted on said arm, said unit having a pair of stylus members for selectively playing vertical-cut and lateral-cut records without adjusting the unit on said arm, said unit also comprising means common to both stylus members for producing electric impulses when either member is in playing position,

2. An electric phonograph reproducer comprising a casing mounted on a movable support, means for selectively playing lateralcut records and vertical-cut records without adjustment of the casing on said support, and mechanism in said casing common to both of said playing means for producing electric impulses when playing either type oi record.

3. An electric phonograph reproducer constructed to selectively play lateral-cut records and vertical-cut records, said reproducer being a unitary structure adapted to be mounted on a movable support and having means for producing electric impulses when playing either type of record without adjusting the reproducer on its support.

4. An electric phonograph reproducerhaving two independently movable armatures, an electromagnetic system for said arma= tures, a stylus member connected to one armature for playing vertical-cut records, and a vsecond stylus member connected to the other armature for playing lateral-cut records.

5. An electric phonograph reproducer comprising electromagnetic mechanism which in cludes a pair of vibratory tensioned, elements operable independently to generate electric impulses, a stylus member connected to one of said elements for playing vertical-cut records, and a second stylus member connected to the other element for playing lateral-cut records. r

6. As a unitary structure adapted to be mounted on a suitable support in record-playing position, an electric phonograph reproducer having mechanism for selectively playing lateral-cut records and vertical-cut records without adjusting said structure on said support, said mechanism including electromagnetic means for generating electric impulses in accordance with the stylus vibrations produced by either type of record 7. An electric phonograph reproducer comprising a casing adapted to be mounted as a unit on a suitable supporting arm for playing records, a pair of independently operable stylus members carried by said casing, one of said members being adapted to play vertical-cut records and the other member being adapted to play lateral-cut records, and mechanism in said casing for producing electric impulses by the vibrations of either stylus member.

8. An electric phonograph reproducer comprising a casing mounted on a movable sup-' port, a pivoted needle arm carried by said casing for playing lateral-cut records, a stylus carried by said casing in position to play vertical-cut records without adjusting the casing on said support, and means for converting the movements of said needle arm and said stylus into electric impulses, said means including an electromagnetic structure common to both of said record-playing members.

9,. An electric phonograph reproducer comprising a unitary structure adapted to be mounted in predetermined position on a suitu able support for playing records, said unitary structure having two independently mounted stylus members for playing lateral-cut records and vertical-cut records respectively without adjusting the reproducer on its support, and electromagnetic mechanism carried y said unitary structure for reducing current impulses when either sty us member vibrates.

10. An electric phonograph reproducer eomprising'a magnetic field structure having two pairs of pole pieces, a vibratory armature operatively associated with each pair or" pole pieces, a stylus member connected to one of said armatures for playing vertical-cut records, a second stylus member connected to the other armature for playing lateral-cut records, and a coil or coils in operative relation to said armatures.

11. An electric phonograph reproducer 1 comprising a casing adapted to be mounted on a suitable support for selectively playing vertical-cut and lateral-cut records, a vertically movable stylus member carried by said casing for playing vertical-cut records, a laterally movable stylus member carried by said casing for playing lateral-cut records, la vi-= bratory element operated by each stylus member, and means for producing electric impulses by the vibrations of each element, said means including an electromagnetic structure arranged between said elements.

12. An electric phonograph reproducer comprising a casing, a field magnet system mounted in said casing, said systemincluding a pair of armatures so mounted as to vibrate in planes substantially at right angles to each other, a stylus member connected to one of said armatures for playing vertical-cut records, a pivoted needle arm connected to the other armature for playing lateral-cut rec ords, and a coil or. coils influenced by the movements of said armatures.

13. An electric phonograph reproducer comprising a casing adapted to be mounted in a certain fixed position on a movable support for playing two kinds of records, a vertically movable stylus member carried by said casing for playing vertical-cut records, a laterally movable stylus member carried by said casing for playing lateral-cut records, a vibratory magnetic element operated by each stylus member, and electromagnetic mechanism mounted in said casing between said elements for producing current impulses by the vibrations of each element.

14. In an electric phonograph reproducer, a field magnet structure having two pairs of pole pieces, a vibratory member in operative relation to one pair of pole pieces, a second vibratory member in operative relation to the other pair of pole pieces, a stylus for playing vertical-cut records connected to said first-named member, a needle arm for playing lateral-cut records connected to the other vibratory member, and a coil or coils influenced by the vibrations of said members.

15. An electric phonograph reproducer comprising electromagnetic mechanism which includes a pair of vibratory elements operable independently of each other for generating electric impulses, one of said elements being arranged to vibrate in a vertical plane and the otherelement vibrating laterally when the reproducer is in playing position, a stylus member connected to said vertically movable element for playing vertical-cut records, and a second stylus member connected to said laterally movable element for playing lateralcut records.

16. An electric phonograph reproducer comprising a casing adapted to be mounted as a unit on a suitable supporting arm for playing records, a pair of independently operable stylus members carried by said casing, one of said members being adapted to play vertical-cut records and the other member being adapted to play lateral-cut records, said stylus members being so mounted on said casing that either member is movable into and out of playing contact with a record without adjustment of the casing on its supporting arm, and means for producing electric impulses by the vibrations of either stylus member, said means being at least in part common to both stylus members.

17. An electric phonograph reproducer comprising a pair of permanent magnets arranged to provide two pairs of pole pieces, a vibratory armature operatively associated with each pair of pole pieces, said pole pieces and armature providing two pairs of airgaps, means for so mounting said armatures that they vibrate in planes substantially at right angles to each other, a stylus member con nected to one of said armatures for playing vertical-cut records, a second stylus member connected to the other armature for playing lateral-cut records, and a coil or coils in operative relation to said armatures.

18. In an electric phonograph reproducer, an elastic magnetic strip mounted to vibrate in a substantially vertical plane, a stylus member connected to said strip for playing vertical-cut records, a second elastic magnetic strip mounted to vibrate in a plane substantially at right angles to the movements of said first-mentioned strip, a pivoted needle arm connected to said second magnetic strip for playing lateral-cut records, and electromagnetic mechanism for producing electric impulses by the vibrations of either magnetic strip, sai elastic strips also acting like springs to hold the connected stylus member and needle arm in normal position.

19. An electric phonograph reproducer comprising a casing adapted to be mounted as a unit on a suitable support in record-playing position, a pair of independently operable stylus members carried by said casing and projecting therefrom at the stylus-holding end, one of said members being for lateral cut records and the other member for verticalcut records, said stylus members being so arranged that the stylus of either member is movable into and out of playing contact with a record without adjustment of said casing on its support, and mechanism carried by said casing for producing electric impulses in accordance with the vibrations of either stylus member, said mechanism being at least in part common to both stylus members.

20. An electric phonograph reproducer comprising a pair 0 selectively operable stylus members, one for playing lateral-cut records and the other for playing Vertical-cut records, and electromagnetic mechanism common to both of said members for producing electric impulses when playing either type of record.

21. An electric phonograph reproducer having a pair of: stylus members. for selectively playing lateral-cut records and 'ertical-cut records, a casing for supporting said members in fixed relation thereto, and means common to both stylus members for geperating current impulses by the movements of either stylus member.

22. An electric phonograph reproducer provided With means for simultaneously supeither stylus member, said mechanism being porting two difierent stylus members in subat least in part common to both stylus memstantially parallel relation for selectively bers. playing different types of record Without adjustment of said supporting means relatively ADULPH A. THGMAS.

to the playing surface of a record, and means common to both stylus members for converting the movements of said members into electric impulses. 23. An electric phonograph reproducer having a holder for removably supporting a needle for playing lateral-cut records, a separate stylus for playing vertical-cut records, said stylus being permanently mounted on the reproducer, a casing on which said holder and said stylus are mounted in fixedrelation thereto for selectively playing either type of record, and common mechanism controlled by said needle and said stylus for generating electric impulses.

24. An electric phonograph reproducer comprising a unitary structure adapted to be supported in record-playing position and ineluding a pair of stylus members supported in substantially parallel relation, one of said members being for lateral-cut records and the other member fdl vertical-cut records, and electromagnetic reproducing mechanism in operative relation to said stylus members,

said mechanism being common to both members for producing current impulses by the vibrations of either member.

25. An electric phonograph reproducer comprising a casing adapted to be mounted as a unit on a suitable supporting arm for playing records, a pair of stylus members carried by said casing in fixed relation thereto, one of said members being adapted to play vertical-cut records and the other member being adapted to play lateral-cut records, said stylus members being so mounted on said casing that either member is movable into and Q5 out o1 playing contact With a record Without adjustment of the casing on its supporting arm, and means for producing electric impulses by the vibrations of either stylus memher, said means being at least in part common 5% to both stylus members 26. An electric phonograph reproducer comprising a casing adapted to be mounted as a unit on a suitable support in record-playing position, a pair of stylus member carried by said casing in fixed relation thereto and projecting therefrom at the stylus-hold= ing end, one of said members being for lateral-cut records and the other member for vertical-cut records said stylus members be ing so arranged that the stylus of either member is movable into and out of playing contact with a record Without adjustment of said casing on its support, and mechanism carried by said casing for producing electric impulses in accordance with the vibrations of

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