US1801276A - Electric phonograph reproducer - Google Patents

Description

A ril 21, 1931. J. K. JOHNSON 1,301,276

ELECTRIC PHONOGRAPH R'EPRODUCER Filed June 14, 1929 elite/0hr: 5375 Patented Apr. 21, 1931 UNITED STATES PATENT OFFICE JOHN KELLY JOHNSON, OF NEW YORK, N. Y.

ELECTRIC PHONOGRAPH REPRODUCER Application filed. June 14,

. tion and which will be sensitive and eflicient form and as madeup to provide apair of upper pole tips'7, 8, extending down through in its operation. j

. The various novel features of construction, combinations and relations of parts by which the foregoing objects are attained will be understood from the following specification.

The drawing accompanying and forming part of thespecification illustrates one simple practical embodiment of the invention, but it should be understood that the structure maybe modified as regards this disclosure without departure from the'true spirit and broad'sco'pe of theinvention.

' Fig. 1 is a side elevation illustrating the position of the unit as in operation; Fig. 2 is a broken'detail view of the device looking in the direction of the arrow 3 inFig. 1; Fig. '3 is alongitudinal section as on substan tially the plane of line 3-3 of Fig. 2; Fig. 49' is a detailed perspective view illustrating the form of the interlocking laminations which make up the pole pieces. j

- The device consists generally of a magnet for producinga strongmagnetic field and an armature adapted to be vibrated in that field and inductively associated with a suitable winding. V

The magnetic field is supplied in the present disclosure by a permanent magnet 5 of the U or horseshoe type and a special feature of this magnet is that its ends are finishedoff on an incline of approximately 45 as indicated at 6. This structure provides areas greater than the-transverse cross-sectional dimensions of the magnet stock, furnishing relatively large contact surfaces for the pole pieces and also enables the magnet to be disposed substantiallyhorizontally while the polar and armaturestructu're occupies a downwardly inclined position, indicated in Fig. 1.

The pole pieces'are shown as of laminated thecenter of the magnet coil 9.and a pair of lgowerpole tips 10, 11. 1

Operating-inthe two magnetic gaps thus 1929. Serial No. 370,801.

provided is the armature 12 supported intermediate its ends by the angularly projecting stub shaft portions 13, 14, the latter being screw threaded to receive the clamping screw 15, which secures the needle 16 seated in the socket 17 provided for it in the armature.

The projecting shaft portions 13, 14 of the armature are yieldingly held by clamp pieces 18, 19, to clamp plates 20, 21, secured by rivets 22 or the like to opposite faces of the pole pieces. The clamp plates 20, 21 are indicated as having angularly turned flanges 23 stifliening-sa-id plates, said flanges being shown as having rounded bearing seats 24 therein and the clamp plates 18, 19, are shown as having V- shaped seats 24, 25 opposed to said rounded bearing seats. The shaft portions of the armature are shown as similarly shaped, that is, with rounded sides for the rounded bearing seats and V-shaped or pointed sides, Fig. 2 to fit the V-shaped seats in themovable clamp plates. Pads 01' cushions 27of rubber or the like are shown as surrounding these shaft or hub portions of the armature and the movable clamp plates are indicated as secured to the stationary or backing plates 20, 21 by screws 28, 29, at opposite sides of the armature axis. By tightening or-loosening these clamp screws at opposite sides of the armature axis, it will be noted that the armature may be rocked one way or the other to properly center it in the magnetic gaps.

By extending the pole tips 7 8 down through the center of the coil, the magnetic effect is increased and a more sensitive and at the same time a more powerful action is obtained. Because of the increased magnetic flow through the coil afforded by the polar projections extending through the coil, the slightest vibrations of the armature are picked up and magnified by the coil, in electrical form.

The pole pieces are suitably secured to the end faces of the magnets, in the present disclosure, by screws 30 extending from the back of the magnet up through the inclined end faces and through the pole pieces, the nuts 31 on the upper outer ends of these screws-binding the pole pieces firmly down on the inclined magnet ends.

The pole pieces are shown as of laminated form and to allow for the peculiar polar arrangement disclosed, the laminations are illustrated in Fig. 4 as made up in four different shapes, a long length 32 equal to the full length of the pole piece, a shorter length 33 cut ofi at the upper end, a wide-section 34 equal to the full width of the pole piece and a narrower section 35. The pieces 32 and 35 are complemental to each other to form the upper and lower pole extensions 7 and 10 and in similar fashion, the shorter and wide sections 33, 34 are complementary to complete the pole projections, it being noted that the wide section 34 overlaps the break be tween the long and the narrower sections 32, 35 and that the long section 32 overlaps the break between the wide section 34 and the shorter section 33. In assembling the L- shaped sections 34, 35 are arranged alternately, a narrow and a wide section, the outer pole pieces 32, 33 are overlaid in alternations and the two sets are interleaved after first passing the polar projections of the inner sets down through the coil- After assembling in this fashion, the two pole pieces may be bound together by the clamp or bridge pieces 20, 21 and by the extra. securing bar 36 at the top, rivets 37 or other suitable fastenings being employed for securing this additional clamp bar. The pole pieces can thus be assembled with the coil and then fastened up as a complete single unit ready to go on the magnet as such, only the two screws and nuts being required for properly fastening the unit to the magnet.

The gain in area attained by facing off the ends of the magnet on inclines permits the piercing of these magnet ends for the bolts 30 without losing too much contact area be tween the pole'pieces and magnet ends. The armature is a relatively short, straight, light piece of metal and therefore particularly efficient for its purpose. The magnet ends may be pierced before the magnet is hardened and theonly machining then required, is the grinding or facing of the inclined ends of the magnet. The spool of the coil isheld inplace by the polar projections 7 8, extending therethrough, the L-shaped form of the magnet laminations providing the necessary space at the sides of these projections to receive the body'of the spool and the coil carried thereby. -The structure is particularly simple and such as can be readily manufactured and assembled at a 10W cost of-production.

The bridging or connecting strips or plates 36, 20, 21 and clamp plates 18, 19, may be of brass or any other suitable non-magnetic material, so as not to short circuit the magnetic flux across the pole tips, 7 8 and 10, 11.

WVhat is claimed is:

1. An electrical phonograph pickup unit, comprising a U-type magnet having its ends angled ofi at an incline to the general plane of the magnet, pole pieces secured in contacting engagement over the slanting surfaces of said angled magnet ends, a coil supported by said polar structure and an armature supported by the polar structure in vibrating relation to the pole pieces and the coil.

2. An electrical phonograph pickup unit, comprising a U-type magnet having its ends angled off at an incline to the general plane of the magnet, pole pieces secured in contacting engagement over the slanting surfaces of .said angled magnet ends, a coil supported by said polar structure, an armature supported by the polar structure in vibrating relation to the pole pieces and the coil, said angled ends of the magnet being pierced substantially at right. angles to said inclined surfaces and securing bolts for the pole pieces extending through said pierced magnet ends.

3. An electrical phonograph pickup unit, comprising a U-type magnet having its ends angled off at an incline to the general plane of the magnet, pole pieces secured in contact ing engagement over the slanting surfaces of said angled magnet ends, a coil supported by said polar structure, and an armature supported by the polar structure in vibrating relation to the pole pieces and the coil, said pole pieces having polar projections extending throughthe coil.

4. An electrical phonograph pickup unit, comprising a magnet, a pickup coil, spaced opposed pole pieces carried by the magnet and having polar projections both extending through said pickup coil and a vibrating armature operatively associated with said polar projections. I

5. An electrical phonograph pickup unit, comprising a magnet, a pickup coil, spaced opposed pole pieces carried by the magnet and having polar projections both extending through said pickup coil and a vibrating armature operatively associated with said polar projections, said pole pieces consisting of generally L-shaped polar laminations arranged in overlapping order with the legs of certain of said L-shaped laminations projecting through said pickup coil. V

6. In a device of the character disclosed. polar laminations of generally L-shaped form and of different dimensions, said laminations being, arranged in over-lapping order to break oints between the laminations, and said laminations in the assembled relation describedhaving opposed polar projections, an open center coil" surrounding said polar projections and a vibrating armature supported to operate between said projections.

7. In apparatus of the character disclosed, a bipolar magnet supported'in a generally horizontal position and having its ends finished on a downwar'd and forward slant, downwardly and forwardly inclined pole piecessecured in flatengagement over said downwardly and forwardly inclined magnet ends, an armature mounted for oscillation in respect to said pole pieces and a winding inductively associated with said armature.

8. In a device of the character disclosed,

a magnet, an open coil, pole pieces carried by said magnet and having pole tips projecting through said coil and an armature mounted in cooperative relation to said pole tips.

m 9. In a device of the character disclosed, a magnet, pole pieces carried thereby and provided with two pairs of opposed pole tips arranged in spaced relation, an armature pivoted intermediate its ends and having its opposite ends positioned in cooperative relation to the two pairs of opposed pole tips and a coil surrounding one pair of said pole tips.

10. In a device of the character disclosed, a magnet, pole pieces carried by said magnet,

said pole pieces having an upper pair of polar projections and a lower pair of polar projections, the upper pair of polar projections being elongatedan'd having clear space about the same, a coil surrounding said upper polar projections and located in the space surrounding the same and an armature in cooperative relation with both the sets of polar projections and supported intermediate its ends in the space between the two sets of polar projections.

11. In a device of the character disclosed, a bipolar magnet having its ends finished on an incline, pole pieces secured in fiat engagement over said inclined en'd surfaces of said magnet and thereby positioned in inclined relation to the body of the magnet, a movable element supported by said pole pieces in inclined relation to the body of the magnet and a power transmission member connected with 40 said movable element in inclined relation to the body of the magnet.

12. In a device of the character disclosed, a bipolar magnet, cooperating pole pieces attached to the poles of said magnet, said pole pieces having separated generally parallel polar projections with clearance space about the same, an open center coil surrounding said polar projections and occupying the clearance space about the same and a movable element disposed in cooperative relation to said polar projections.

In testimony whereof I afiix my signature.

J. KELLY JOHNSON.

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