US3689210A

US3689210A - Apparatus for producing a magnetic return structure

Info

Publication number: US3689210A
Application number: US115676A
Authority: US
Inventors: Karl-Ulrich Stein
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1971-02-16
Filing date: 1971-02-16
Publication date: 1972-09-05
Anticipated expiration: 1989-09-05

Abstract

A magnetic return structure having a system of control lines for use in a magnetic storer and apparatus for producing the same. A parallel series of conductors are applied to both sides of a foil of insulating material and a keeper composition is applied to the exposed foil and conductors in a manner that eliminates any air gaps therebetween without producing undesirable mechanical disruptions of the system.

Description

United States Patent Stein [54] APPARATUS FOR PRODUCING A MAGNETIC RETURN STRUCTURE [72] Inventor: Karl-Ulrich Stein, Munich, Germany [73] Assignee: Siemens Aktiengesellschaft,

and Munich, Germany [22] Filed: Feb. 16, 1971 [21] Appl. No.: 115,676

Related US. Application Data [62 Division of Set. No. 818,884, April 24, 1969,

abandoned. I

Berlin 18/47 C, DIG. 33, DlG, 44, DIG. 60, DIG,

' 1 51 Sept. 5, 1972 Primary Examiner-Robert L. Spicer, Jr. Attorney-Carlton Hill et a1.

57 ABSTRACT A magnetic return structure having a system of control lines for use in a magnetic storer and apparatus for producing the same. A parallel series of conductors are applied to both sides of a foil of insulating material and a. keeper composition is applied to the exposed foil and conductors in a manner that eliminates any air gaps therebetween without producing undesirable mechanical disruptions of the system.

[56] References Cited 2 Claims, 3 Dra UNITED STATES PATENTS Y a 1,190,072 7 /1916 Aiken ..18/D1G. 62

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APPARATUS FOR PRODUCING A MAGNETIC RETURN STRUCTURE This application is a divisional of my copending application Ser. No. 818,884, now abandoned, filed Apr. 24, 1969.

The invention relates to a magnetic return structure and more particularly to magnetic return structures for use in magnetic stratified storers and means of forming the same.

It is a known practice to utilize ferrite keepers with magnetic return structures. The present day practice is to produce the ferrite keepers as independent structures. The keepers are composed of a ferrite powder, an organic bonding agent such as silicon rubber, a solvent such as methyl-ethyl ketone, a suitable hardener and, in certain instances, additional additives. These keepers are formed into hardened (or solidified) plateshaped bodies which are incorporated into magnetic storers as magnetic return structures. However, such known keepers have a number of drawbacks, including inability to form an intimate relationship with magnetic storers of irregular shapes; inability to eliminate air gaps between the keeper and the storer; inability to attain uniform magnetic contact between the keeper and the storer, etc.

It is therefore an important object of the invention to provide a magnetic return structure eliminating the aforesaid drawbacks.

It is another object of the invention to provide an apparatus for forming an improved magnetic return structure.

Yet another object of the invention is to provide a magnetic return structure having a particularly high return effect for the magnetic field of a magnetic storage layer.

Other objects, features, and advantages of the invention will become more apparent from the following detailed disclosure and drawings attached hereto, in which certain preferred embodiments of the instant invention are shown by way of illustration.

These and other objects of the invention are accomplished by applying to the keeper material (ferrite, binder, solvent, etc.) to a magnetic storage layer while the keeper material is still in a fluid-like or flowable state and allowing the keeper materials to solidify on the storage layer to form an integrally joined mechanical unit.

As indicated hereinbefore, a system of control lines for magnetic storers is preferably constructed by applying a parallel series of conductor pieces on a foil (generally only a few pm thick), as on each of the two sides thereof. Conductor matrices having a series of such conductor pieces crossing one another are, for example, utilized in magnetic stratified storers. In order to improve the magnetic return of such magnetic stratified layers to the side of the conductor matrix, keeper structures are utilized. Keepers are plateshaped bodies composed of soft-magnetic materials (i.e., an elastomer impregnated with a ferrite powder).

FIGS. 1 and 2 are schematic elevational side views of a system of control lines having ferrite keepers attached thereto in accordance with the principles of the invention; and

FIG. 3 is a simplified schematic elevational view of a loaded pressure apparatus in accordance with the prin-- ciples of the invention.

In accordance with the principles of the invention, the air gap for the magnetic return is minimized by applying the keeper material in a fluid state directly onto the system of control lines and allowing it to harden or set thereon. In this manner, the keeper is intimately bonded with the foil of insulating material as well as with the series of strip-like connector pieces disposed on the foil.

Surprisingly, the manner of applying the keeper material in accordance with the invention onto a magnetic storage layer does not produce the distortive mechanical changes in the system. It would normally be expected that the setting or hardening of an organic bonding agent (i.e., silicon rubber) would materially distort the thin foil of the system. Further, when a holding frame is utilized (as disclosed in copending German patent application Ser. No. S 102 858 1X c/2la it might be expected that this curing or hardening procedure would cause the storage layer to break away from the frame through shrinkage or the like. However, as indicated, no distortive, destructive or disruptive mechanical changes occur.

An advantage of the magnetic return structure of the invention resides in that the solidified keeper structure does not have to be squeezed or pressure-forced against the magnetic storer system. This eliminates the complication from the known process of bonding keepers to storers. Further, the magnetic return structure of the invention is particularly adaptable to irregularly-shaped magnetic storers, such as those having an uneven surface and/or a curved surface. In other words, a keeper or magnetic return structure formed in accordance with the invention has an irregular form mating with the particular form (curved or otherwise) of the system of control lines (i.e., the magnetic storer system). Additionally, the keepers applied in the manner of the invention do not have any air gap between the keeper surface and the magnetic storer surface.

In certain instances where an extremely unevenly shaped magnetic storer is encountered, it is nevertheless desirable to apply a force onto the surface of the fluid-like keeper material until it has set or hardened. Accordingly, the invention also provides a preferred force applying apparatus for use in such instances. The details of this apparatus will be described more fully hereinafter.

The magnetic contact achieved by the ferrite keepers applied in the manner of the invention to a magnetic storage layer is extremely intimate. Air gaps between the magnetic storage layer and such ferrite keepers are reduced to a minimum. As will be appreciated, the fluid-like material of the keeper fills up all of the space between the conductors and the supporting foil. This intimate relationship between the keeper and the storer can readily be demonstrated. A system of conductors is violently removed from ferrite keepers attached thereto in the manner of the invention and it is noted that the surface of the keeper that was in contact with the conductor has been imprinted with the pattern of the conductor series. This is the case even when the conductors are only a few pm thick.

It is particularly advantageous to press the fluid-like keeper material throughout its curing or hardening process against the system of control lines with an appropriate means. A vacuum pressure apparatus is a particularly well suited means to apply such pressure during this step of the manufacturing process. Such an apparatus is particularly adaptable to this process since it can exert a uniform pressure on the keeper material surface and thereby attain an intimate and uniform contact between the cured keeper and the magnetic storers. Further, a vacuum apparatus constructed in accordance with the principles of the invention has a portion thereof permeable to gases and/or vapors and thereby allow the withdrawal of volatilized solvents and/or diluents from the keeper material. As indicated hereinbefore, the keeper material is a mixture of ferrite powders, organic binder, solvents, etc. The permeability feature of this apparatus allows withdrawal of solvents and/or diluents from the structure during the continual application of force.

Additional details of the invention are disclosed in the preferred embodiments shown on the drawings and reference is now made to the Figures thereof, wherein like reference numerals refer to like parts.

FIGS. 1 and 2 illustrate a foil 1 of insulating material supporting a conductor 3 (diagrammatically illustrated) on one side thereof and another conductor 4, in the form of a series of parallel pieces, on the other side of the foil 1. These conductors 3 and 4 define the control lines of the system. A ferrite keeper 2 is attached, in accordance with the aforesaid procedure, to one or both of the conductors 3 and 4. It will be noted that the ferrite composed keeper 2 makes direct and intimate contact with all of the exposed surfaces of the conductors 3 and/or 4 and the surface of the foil 1. In this manner, an intimate unseparated attachment between the keeper and the system of control lines is attained.

FIG. 3 illustrates a vacuum pressure apparatus of the invention. A tub-shaped receptacle 11 receives the system of control lines (composed of a foil 1 carrying conductors 3 and 4 thereon) along with the fluid-like material of the ferrite keeper 2. A cover plate 12 is disposed on top of the keeper material. The plate 12 is gas permeable and may be composed of any suitable gas permeable material, such as paper. An elastic shim 13 is disposed on top of plate 12. The shim 13 is provided with a plurality of projections, knobs or other such spaced pieces 13a. The shim 13 lies on the plate 12 in such a manner that it transfers a maximum amount of uniform pressure onto the cover plate 12 and yet provide a substantial area of free space 16 above the plate 12. Gases and/or vapors passing through plate 12 enter free space 16 and are removed therefrom. Shim 13 can be composed of any elastic material, such as rubber in the form of, for example, a playing surface of a table tennis bat. A suction line 14 is mounted to provide a means of communication between the free space 16 and a vacuum source (not shown). An elastic closure plate 15 is disposed on top of the shim 13. The closure plate 15 is substantially gas impermeable but is sufficiently flexible to be responsive to atmospheric pressure. In the arrangement shown, the upper or exposed surface of plate 15 is in direct contact with ambient atmosphere. The plate 15 is also provided with a circular bead or the like 17 along its peripheral edges to accommodate movement of plate 15 as it responds to atmospheric pressures. A suitable O-ring or the like 18 provides a gas seal between receptacle 11 and cover plate 15. Of course, if desired, shim 13 and plate 15 may be combined into a single pressure plate having a plurality of projections along a surface thereof.

As is apparent from a consideration of the apparatus, it is opened between plate 15 and the upper edge of receptacle 11 by the removal of seal 18. When the receptacle is open, the shim member 13 and the gas permeable cover plate 12 are removed and the control line system of insulating foils and conductors are placed inside of the receptacle. Then the fluid-like ferrite keeper material 2 is poured on top of this system and plate 12, shim 13 and cover plate 15 are reassembled in the manner shown. The edges of the receptacle 11 and plate 15 are then sealed with the O-ring 18 and vacuum is applied via line 14 to evacuate any air from free space 16. As this air is evacuated, atmospheric pressure uniformly forces plate 15 downwardly and exerts a uniform pressure on the shim 13 and the plate 12 causing a uniform compression of the keeper material. This compression further insures that the fluid-like keeper material expels any gas therein (including vaporized solvents, etc.) and uniformly contacts all of the exposed surfaces of the foil and conductors. As indicated, any gases within the keeper material are able to pass from the keeper material through the gas permeable plate 12 and out of the apparatus via lines 14. Otherwise, such gases and/or vapors would be entrapped within the keeper material thereby providing air spaces therein which are undesirable. The vacuum is maintained until the ferrite keeper material hardens or sets and is then released and the apparatus opened to remove the unitary structure of the system of control lines having a flexible keeper intimately bonded thereto. The pressure apparatus is reusable any number of times and the materials composing the apparatus are carefully selected and assembled that it has an extended useful life.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. An apparatus for the production of a flexible keeper in intimate unseparated attachment with a magnetic storage layer comprising, a receptacle having an open top for receiving a system of control lines and a fluid-like keeper material, a gaspermeable cover plate fitting said open top and being superimposed onto the fluid-like keeper material, a gas-impermeable pressure plate adapted for mounting above said cover plate and being movable in response to pressure variations, said pressure plate having a plurality of projections extending from a surface thereof, said projections being in pressure-transmitting contact with said cover plate and defining free space between said cover plate and said pressure plate, a vacuum source, a vapor passage means providing communication between said free space and said vacuum source, and a seal means providing a vapors seal between said pressure plate and said receptacle whereby vacuum is applied to said free space causing application of pressure on said cover plate and fluid-like keeper material.

2. The apparatus as defined in claim 1, wherein the pressure plate is composed of a shim member having a plurality of projections extending from a surface thereof and a flexible closure member superimposed on said shim member and being movable in response to pressure variations.

Claims

1. An apparatus for the production of a flexible keeper in intimate unseparated attachment with a magnetic storage layer comprising, a receptacle having an open top for receiving a system of control lines and a fluid-like keeper material, a gaspermeable cover plate fitting said open top and being superimposed onto the fluid-like keeper material, a gasimpermeable pressure plate adapted for mounting above said cover plate and being movable in response to pressure variations, said pressure plate having a plurality of projections extending from a surface thereof, said projections being in pressure-transmitting contact with said cover plate and defining free space between said cover plate and said pressure plate, a vacuum source, a vapor passage means providing communication between said free space and said vacuum source, and a seal means providing a vapors seal between said pressure plate and said receptacle whereby vacuum is applied to said free space causing application of pressure on said cover plate and fluid-like keeper material.