US2466469A - Means for mounting the armature of a magnetic phonograph record reproducer and recording head - Google Patents

Description

l Apu-1l 5, 1949. R. w. NlcHoLLs 2,466,469

MEANS FOR MOUNTING THE ARMATURE OF A MAGNETIC PHONOGRAPH RECORD REPRODUCER AND RECORDING HEAD Filed oct. 2e, 1945 INVENTOR.

A'ITD R N EYE Patented Apr. 5, 1949 MEAN S. FORA MQUN TIN G' THEARMATUREIOF A" NIAGNETICPHONOGRAPH" RECRD" RE- PRODUCER AND' RECORDING HEAD RalplifW-lliam Nicholls, Miami Shores, Fla.

ApplicationzOctober 26, 1945, Serial No. 6243843 37 Claims.. 1

The invention relates to a device forrecording and reproducing acoustic vibrations.

The primary object of theinvention 'is' the provision ofa device-of this character, wherein'the mountingl of an armature in a magnetic phonograph record reproduceror the recording head is had' without' the usual bearings, retaining springs'or rubber damping mediums,- the device being of novel construction and is unique` in the arrangement of its parts, for the successfuloperation thereof*I With this thought inmindthis invention contemplates a pickup needle carried by an armature', having. a` horizontally disposed` shaft: integral therewith with an extending end of the shaft journaled in a bearing on a base plate end with the armature positioned between the pole pieces-of a permanent magnet of the horseshoe type, and with coils around upwardly andodownwardlyextending arms of thel armature and positionedin gaps in said pole pieces.

Theincorporation-of the shaft in the vibrating system of phonographv reproducers and recording cutter heads eliminates the use of rubber bearings and damping means, thus enabling the pick-up to be adj-usted to a very low` mechanical impedance, therefore, a very light pressure is required on the record grooves for it to track and operate successfully. This results in long usage from lacquer or commercial recordings due to the extremely low mechanical impedance and the slight pressure on the record.

Another object of the invention, therefore, is the provision of a device of this character, wherein it is simplified for manufacturing assembling, eliminates rubber bearings, springs and reduces all friction, at the same time being rigid, but allows the armature fastened in place to twist on an axis, the twist being slight, and the pole pieces, magnet and clamp are assembled on a base plate or in a die casting or plastic or punch pressed phonograph arm, so that very slight pressure is necessary on records which increases the number of playings before surface of each is cut up by the needle, thereby increasing the length of usefulness.

A further object of the invention is the provision of a device of this character, which is simple in construction, thoroughly reliable and eicient in operation, strong, durable, neat in appearance, light in weight, and inexpensive t manufacture and install.

With these and other objects in view, the invention consists in the features of construction, combination and arrangement of parts as will 2 hereinafter be more Afully described, illustrated'in the accompanying drawing, whichishows the preferred embodiment of the invention, and is pointed out in the claims hereunto appended;

In the accompanying drawing- Fig-ure 1 is a top plan view of the device constructed f in accordance with the invention;

Figure 2'y is a sectional'view taken on the-line 2-2 of Figure 1 looking in the` direction ofthe arrows;

Figure' 3- is an elevationy of thev devicelooking towardthe needle holding endf ofI thearmature of*I the device;

Figure 4 is a detail plan view of one part of the-device removed; i

Figure 5isa sectional view taken onthe line 51-5`of Figure 4 looking inthe direction-offl the arrows;-

Figure 6" is a crossl section throughthe device, being taken on line 6-6 of'Fgure 1.

'Similar referenceV characters indicate corresponding parts throughout'the' severaliviews in the drawing. i

Referring to the drawing in detail, theA device constituting the present invention, comprises an armature I 0, made as a whole with avshaft II which will allow it to track in an oscillating motion. This shaft II at its inner end is removably held in a bearing I2 lby a releasable clip I3 thereon, and such bearing is supported by a base plate I4, the clip being connected by a fastener I5.

The plate I4 supports and has insulated therefrom a U-shaped magnet I6, and disposed between the pole pieces at the ends of the two arms A-A thereof, and under the balanced inluence of the magnetic fields produced by the permanent magnet is the armature III. The pole pieces which are of ferromagnetic material, for instance, soft iron, are integral and in intimate contact with the permanent magnet I6.

Encircling the armature I 0 above and below the shaft I I are the two coils I1 and I8, of identical construction, which coils can be connected in series or in parallel at will and through which flows the impressed amplified current during recording and the induced current during reproduction. The formation of the shaft Il, as indicated at I9 enables the tracking thereof in an oscillating motion, as before stated, as it permits of a slight twist to such shaft, at this point I9, which should be obvious.

The armature I0 is a part of the shaft II and has formed in its lower end a clearance for a recording needle 20, adapted to be detachably held in place by a. set screw 2l threaded into a lateral boss 22 projected beyond the overlying relation of the coils I1 and I8, respectively. The base plate I4 is also provided with a recess 23 for the passage of the needle 20 through the same. The formation I9 of a thinned radial web construction, the webs being denoted at 24, respectively. A

The device constructed in accordance with the invention is devoid of pivot bearings, springs or damping mediums, as will be apparent from Figures 1, 2 and 3 of the drawing. It is, of course, understood that in lieu of the needle 20 a permanent sapphire point may be substituted in its place.

What is claimed is:

l. Means for mounting the needle carrying armature of a magnetic phonograph reproducer or recorder comprising a bearing post xed rigidly within the reproducer or recorder, a hollow shaft having the armature fixed rigidly to one end thereof and having the other end fixed rigidly to the bearing post, the shaft being provided between the bearing post and armature with longitudinal slots presenting a pair of vertical ribs and a pair of horizontal ribs adapted to hold the shaft and its armature against vertical and lateral movement but adapting the shaft to twist about its longitudinal axis as the armature is electrically or mechanically oscillated.

2. In an armature for an electro-magnetic pickup device, a vertically disposed armature head having a needle socket in the lower end and having a horizontally dispo-sed tubular shaft extended from a point in the armature head midway of the height thereof and perpendicularlyfdisposed in relation to said head, said shaft having longitudinally disposed Islots therein with the slots centered in diagonally positioned planes at 45 degrees to the vertical and horizontal planes through the shaft providing comparatively thin aligned vertical and horizontal webs connecting the ends of the shaft whereby with the shaft supported by the end opposite to that on which the armature head is positioned the head is suspended with the webs preventing vertical and horizontal move- 45 umher 4 ment and providing oscillating or twisting vibrations therein.

3. In an armature for an electro-magnet pickup device having a U-shaped magnet with the armature suspended between the poles thereof, the combination which comprises, a vertically disposed armature head having a needle holding socket in the lower end and having a horizontally disposed tubular shaft extended from a point in the armature head midway of the height thereof and perpendicularly disposed in relation to said head, said shaft having longitudinally disposed slots therein with the slots centered on diagonally positioned planes at 45 degrees to axially extended vertical and horizontal planes of the shaft providing comparatively thin aligned vertical and horizontal webs connecting the ends of the shaft whereby with the shaft supported by the end opposite to that on which the armature is positioned the head is suspended with the webs preventing vertical and horizontal movement and providing oscillating or twisting vibration in the shaft, and a bearing post in which the end of the shaft opposite to that on which the armature head is positioned, for supporting the armature with the said shaft thereof positioned midway between the arms of the U-shaped magnet and in a plane extended through said arms and midway of the width thereof.

RALPH WILLIAM VNICHOLIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Crouse Nov. 24, 1931 Guedon Mar. 19, 1935 Harrison s Jan. 7, 1936 Kendall Sept. 14, 1937 FOREIGN PATENTS Country Date Great `Britain Apr. 24, 1940 Number

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