US3026379A

US3026379A - Electromagnetic transducer

Info

Publication number: US3026379A
Application number: US754762A
Authority: US
Inventors: David J Carpenter
Original assignee: Ex-Cell-O Corp
Current assignee: Ex-Cell-O Corp
Priority date: 1958-08-13
Filing date: 1958-08-13
Publication date: 1962-03-20
Anticipated expiration: 1979-03-20

Description

March 20, 1962 D. 1. CARPENTER 3,026,379

l ELECTROMAGNETIC TRANSDUCER Filed Aug. 13, 1958 Z7 W M 7M We W United States Patent O 3,026,379 ELECTROMAGNETIC TRANSDUCER David J. Carpenter, Perknsville, Vt., assignor, by mesne assignments, to Ex-Cell-O Corporation, Detroit, Mich., a corporation of Michigan Filed Aug. 13, 1958, Ser. No. 754,762 7 Claims. (Cl. 179-1002) This invention relates to magnetic intelligence recording and reproducing devices in general, and in particular to improvements Vto the electromagnetic transducers or heads employed in said devices to impart the recording to the movable intelligence storage medium or to read therefrom such imparted intelligence.

The principal object of the invention is to provide an improved transducer head structure in which the transducer core is ixedly supported in a casing to achieve and retain the desir-able correct alignment of the transducing gap transverse of the direction of the motion of the medium.

Another object of this invention is to provide a head which may be assembled in a unitary structure from components which are easily manufactured to provide a transducer having constant magnetic characteristics.

A further object of this invention is to provide a transducer head that can be assembled utilizing various previously manufactured coils.

Another object of this invention is to provide a head wherein the core at the pole tips may be provided with magnetic shielding. A

The various features of the invention will be described in embodiments thereof with reference to accompanying drawings in which:

FIG. l is a side sectional view of a head of this invention.

FIG. 2 is an end view viewed from left of FIG. l.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 1.

FIG. 4 is a plan view of a magnetic core piece.

FIG. 5 is a side sectional view illustrating a variation of the invention in a dierent embodiment.

FIG. 6 is an end view viewed from left of FIG. 5.

FIG. 7 is a fragmental sectional View taken along line 7--7 of FIG. 6.

In FIG. l a body 11 and a cap 12 together constitute a casing 13 for the head components. The body 11 is generally tubular and has a central hole enlarged at one end by a counterbore 14 which is adapted to retain a lead connector or the like. The exterior of the body 11 is provided with a flattened reference surface portion 10, for the purpose of positioning the transducer with reference to the record medium as described in the copending application Serial No. 684,278, filed September 16, 1957 by H. Taft assignor to the same assignee as the present invention, and which has now matured as Patent No. 3,001,181, issued on September 19, 1961. The end of the body 11 opposite counterbore 14 has on its exterior a reduced diameter portion 15 terminating in a shoulder 16. The same end of the `body 11 includes a recess 17 running crosswise of the body, and a keying slot 18, disposed transversely thereto (FIG. 3). The sides of the recess and the slot are located at right angles relative to each other, and the flattened portion 10 is oriented parallel to slot 18 as viewed in FIG. 2.

The cap 12 has the same outside diameter as body 11 and also has a cylindrical bore 20 adapted to snugly tit over the reduced portion 15. Cap 12 includes an inwardly tapering ange portion 21 which terminates in a hole 22 in the end portion thereof.

FIG. 4 illustrates a half core 24 made of suitable material, such as ferrite or the like, as is well known in the art.

Mice

Two such half cores are employed in each head and the other half core is indicated in phantom. The

half core

2,14

is generally U-shaped having two legs connected by al web and has a thickness to snugly fit in slot 18 (FIG. 3). One leg of the core is shaped to form a pole piece with a flux gap defining face 25 and the other leg 23 terminates in a surface 26 adapted to be positioned in contact with the like surface of a complementary mating core in the completed assembly. To initially deiine and permanently secure the desired ux gap, a sliver shim 27 of suitable material, e.g. silver, and of proper thickness is inserted between faces 25-25 of the half cores 24. A coil 28, that may be previously manufactured, may be placed over the leg 23 and within the recess 17 to complete the assembly of elements.

The transducer head may be assembled by pasting the Sliver 27 to the face 25 of a half core 24 and slipping the coil 28 over its leg 23. The leg 23 of a second half core 24 is then inserted in the coil until the surfaces 26-26 are brought in intimate contact with eachother and face 25 of this second half core a-buts sliver 27. This now forms a sub-assembly, being the magneto-electric operative portion of the transducer, which is inserted in the body 13 where slot 18 provides a seat for the cores 24-24 and the cavity partly formed by recess 17 affords space for the coil 28, the leads thereof passing towards counter- `bore 14. The cores may be cemented to the sidewalls of slots 18. The cap 12 is then pushed over the reduced body portion 15, and the tapered interior portion 21 of the cap abuts complementary tapered portions of the cores 24-24 to securely hold the sub-assembly with the cores abutting the bottom portions of slot 18. The completed assembly may then be potted in a manner well known in the art, i.e. the interioris lled with a suitable thermo-setting plastic or the like Iin liuid form and cured.

The flattened surface 10, according to aforesaid Patent No. 3,001,181, is for the purpose of orienting the magnetic linx gap between the pole pieces of the core transverse of the direction of movement of the track of the storage medium when the head -is assembled in its support. To fully utilize the capacity of the record medium it is desirable that the recording tracks thereon be spaced as close as possible, and to inhibit cross-talk between adjacent transducers it is of utmost importance that the magnetic ux gap be exactly aligned along the recording track, particularly when two heads are applied to the same track, e.g. when using separate write and read heads spaced along the track. Further, because of aforesaid close track spacing it is desirable to magnetically shield the pole pieces. A variation of the present invention to fulll the requirement of orientation and shielding is shown in the embodiment of FIGS. 5, 6 and 7.

In this embodiment all the elements are generally similar to those described in FIGS. 1 through 4 with the difference that a cap 52 has been substituted for cap 12. The cap 52 differs from the cap 12 in that the inwardly tapered ange portion 21 terminates in a wall portion 51 ciose off the end of the cap. This wall 51 contains a slot 58 adapted to fit snugly against the pole piece tips of the half cores 24-24 and substantially surrounds these tips. In the completed assembly the slot 58 will then serve as an effective guide to orient the pole piece in desired manner, and by choosing a material for the cap which has high permeability, e.g. Mu-metal, the desired shielding eect is achieved. A second slot 59 may be provided as shown in FIGS. 6 and 7 to provide clearance for shim 27 and to facilitate the potting operation. When the assembly is completed the cap and the pole piece tips may be machined to afford a clearance of the head relative the recording medium such that only the pole piece tips and the immediate portion of the cap protrude without departing from the spiritdand scope of the inven-V tion as Ydefined in the appended claims.

I claim:

1.. An electromagnetic transducer head for coaction with a magnetic intelligence recording-reproducing device comprising; aY magnetic core -in two sections of generally U-shaped form, one leg of said U forming a pole piece, and the other leg of. said U forming the other pole piece, said sections mounted such that the extremes of the pole piece legsface each other in spaced relationship to provide a magnetic ux shaping` gap andthe extremes of the other legs abut eachother, a Wound magnetizing coil surrounding Vsaid abutting legs, a casing body of tubular form, means defining a referencing keying slotV in one end of said casing body, the keying slot cooperating with the4 magnetic corel for orienting theV core with respect to the lbody,and a cap fitted over 4the body to holdthe core within said slot. v

2. An electromagnetic transducer head as defined inV claim 1 wherein the exterior of the vbody is provided with a at loc-ating reference surface portion extending in one direction substantially parallel to the body axis and in the' otherKV direction parallel to said slot. Y

3.v A magnetic transducer head as deiined in claim l wherein an' open ended recess is provided in the' same end the slot said recess -being positioned at right' angles to theV slot being adapted to receive andy containsaid wound magnetizing coil.

4, A magnetic transducer heady as d'eiinedA in claim 1; wherein the body and the cap are o` thev same outside diameter tofor-m -a unitary structure of general cylindrical form providing an envelope for the core with its pole pieces in proximity of one extreme and having provisions in the other extreme to attach leads for the magnet-izing coil.

5. An electromagnetic transducer head having a core in two sections each being of substantially U-shaped configuration, the end faces of the -irst legs of the substantially U-shaped core sections ybeing positioned to form ama-gnetc ux shaping gap, and the extremes ofthe second legs of the substantiallyV U-shaped 'core sections being in intimate contact, a magnetizing coil surrounding said second legs, a tubular casingbody providedwith a keying slot in one end thereof, said' keyingY slotV providing', a` seat' Vfor theV said core and orienting the same centrally and radially with the legs forming the iiux shaping gap protruding outside the extreme of the body, a partially closed end cap having a slit thereinV telcscoped over the body in a manner that between an interior portion of its closed end and the bottoney of said keying slot the core is iixed axially, said slit in the closed end surrounding the protruding legs.

6. A magneticl transducer head asl deiined in claim 5 wherein the core terminates ilush with the outer end surface of the cap.

7. A magnetic transducer headV as deiined in claim 6 wherein said cap is made from material of high permeability to provide magnetic shielding for the core.

References Cited' inthe le of this patent UNITED STATES PATENTS 2,523,515 Porter Sept. 26, 1950 2,756,280 Rettingery July 24, 1956 2,910,544 McNutt Oct. 27, 1959 FOREIGN PATENTS 751,405 Great Britain .lune 27, 1956 1,140,928 France Mar. 1l, 1957