US1796238A - Pick-up device - Google Patents

Description

March 10, 1931- J. H. BUTCHER ET AL 1,796,238

PICK-UP DEVICE Filed May 1, 192

Invenfors Jchn H. Bufcher, FY six pwms,

Their" Afiorne g.

Patented Mar. 10, 1931 UNITED STATES ATE T OFFICE" JOHN H. BUTCHER, OF RUGBY, AND FELIX P. WILLS, OF UXBRIDGE, ENGLAND, ASSIGN- ORS TO GENERAL ELECTRIC COMFANY, A CORPORATION OF N EW YORK PICK-UP nnvrcn Application filed May 1, 1925, Serial No. 105,970, and in Great Britain May 26, 1925.

Our invention relates to apparatus by means of which the movements of a rapidly oscillating member are converted into corresponding electrical oscillations. More particularly our invention relates to a sound reproducing apparatus, such for example as a phonograph, wherein the vibrations of a member engaging a sound record are converted into electric oscillations which by to other means may be amplified and converted into sound waves and an object of our invention is the provision of an improved apparatus of this character.

Our invention will be better understood from the following description taken in connection with the accompanying drawing, and

its scope will be pointed out in the appended claims.

Referring to the drawing, Fig. 1 is a cross acsectional view of one embodiment of our invention and Figs. 2 and 3 are similar views showing modifications thereof.

Inasmuch as apparatus of the type to which our invention relates are now com- 25 monly known as pick-up devices, this term will, for convenience, be used throughout the description and claims in referring to this apparatus.

In the drawing we have shown a main supporting member l in the form of a ring which is adapted to be applied to the end of the tone arm of a phonograph in place of the usual diaphragm supporting head. In this connection we use the term phonograph as applying to any sound reproducing or talking machine having a stylus which is vibrated by contact with a sound record. A permanent ma net 2, which in Fig. 1, is in the form of a fl at annulus is supported from the ring 1 by the sleeve 3 which preferably is of magnetic material and forms a pole piece for the magnet. Secured to the outer periphery of the magnet is the magnetic member 4 having the central core or pole piece portion 5 which with the sleeve 3 forms an annular air gap in the magnetic circuit. In this air gap is the spool 6 which is of light construction and which carries the coil 7. The spool with the coil thereon is supported centrally in the air gap and isoperatively connected bythe rod 8 and arm 8 to the stylus holder 9 having the stylus 10 whereby vibrations of the stylus cause corresponding vibrations of the coil 7 in the axial direction. For centralizing the coil in the air gap we provide the member 11 which preferably is in the form of a mica diaphragm having holes therein to make it noiseless. However, this member may, if desired, be in the form of a spider or may be a diaphragm of other material than mica. The member 11 is shown flexibly supported between the rings 12. Thedisk 13 of insulating material is secured to thesleeve 3 and carries the binding posts 14: connected respectively to the two ends of coil 7.

In the modification shown in Fig. 2 the arrangement of parts is substantially the samev as in Fig. 1 except that the permanent magnet 17 has an outer flange portion which engages the magnetic member 18 of corresponding modified form.

In the modification shown in Fig. 3 the magnet is flat as in Fig. 1, a tubular magnetic member 20 supports the stylus holder 9 from I the periphery of the magnet and a second magnetic member 21 connects with the inner portion of the magnet and, in cooperation with the member 20, forms the air gap in which moves the coil 22 carried by the spool;

23. The spool 23 in this case connects directly with the arm 8 and centralizing member 11. The member 21 is secured directly to the supporting member 24. corresponding to member 1 of Figs. 1 and 2.

In the use of this apparatus, the usual head carrying the sound diaphragm is removed from the tone arm of the phonograph and the support 1 or 24 is applied thereto with the stylus resting on the moving record in the usual manner. The resulting vibrations of the coil cause electric impulses to be induced therein. These impulses may be amplified by suitable electron discharge amplifying devices and then converted directly into sound. as for example by a telephone or a loud speaker, or if desired they may be utilized to modulate radio transmission waves.

What we claim as new and desire to secure by Letters Patent of the United States, is,

'1. In combination, magnetic poles arranged to form'an' air gap, a coil mountedin the air gap coil support means extending through oneof said poles and means adapted to be vibrated by engagement with a sound. recordfor bodily moving said support and said coil in an axial direction.

2. A p ck-up device comprisingina-gn'etic poles arranged to form an air gap-thereima coil mounted insaid.air -gap, coilsupport means extending through one of said poles and arr'anged'to move said coil'axially a stylus, and means connecting the stylus with said support means.

3. Api'ck-up device comprisinga support, a magnetic member'compris'iiig a magnet having-an annular airgz'ap, a coil, means com, prising a noiseless diaphragm foncentralizing' the coilin theair gap, astyius, and means connecting the stylus with the coil through said diaphragm whereby vibrations of thestyluscaiise the coil to vibrate axially.

4. A phonographic pick-up device comprising asupport adapted to be'attached to the tone arm vof a phonograph, a permanent magnet, a magnetic member associated with the magnet and forming therewith an annu- '.lar'air gap a"generative-coil, means compiis nga noiseless di phragmfor supporting the coilin'theair gap for axial inovementtherein, a stylus adapted 'to follow a a phonograph recoi'd,'*anda connection comprising a pivotal support between the'stylus andithe'coil. 1

v In'witnes's whereof, ,we have hereuntos't our hands thisj13th dayof April, 1926. JOHN BUTCHER.

FELIX P. WILLS.

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