INTEGRATED MAGNETIC HEAD, PARTICULARLY FOR DATA STORAGE UNITS

Abstract: Integrated magnetic head which can be used in data storage units or in other digital devices cooperating with magnetic data carrier media, as tapes or discs. The magnetic head comprises a substrate (15) with a holding surface (13) perpendicular to the plane of the magnetic data carrier, a head unit (10) made in form of a layer on the holding surface (13) and two input/output terminals (1, 2) wherein the head unit (10) comprises a frontal stripe (11) arranged along the frontal face (14) and connected electrically to the two input/output terminals (1, 2). The proposed integrated magnetic head ensures a high effective conversion of the magnetic and electrical energy respectively into electrical and magnetic energy without the disadvantages following from the use of air gaps in the known solutions.

Description: INTEGRATED MAGNETIC HEAD, PARTICULARLY FOR DATA STORAGE UNITS Background of the invention The invention- relates to an integrated magnetic head, particularly for use in data storage units, comprisin a substrate with a frontal face arranged oppositely to the surface of a magnetic data carrier and with a holding surface arranged perpendicularly to the frontal face, a head unit with a ferromagnetic element made in form of a layer on the holding surface and two input/output terminals connected to the head unit. The magnetic head according to the invention is aimed for use in data storage units of computer systems, however, in cooperation with convenient electronics it can be used in every digital equipment based on magnetic data carzier, as tape or disc. The integrated magnetic heads used in the known devices based on digital principle comprise a ferromagnetic thin layer produced by a known convenient method, e.g. a vacuum technology method (metal vaporization, metal sputtering etc.) or other on a substrate of material selected according to the requirements. The most widely used are the silicon monocrystals, ceramics, e.g. on the • basis of lgO- j , and glass. The sub±rate is shaped rectangul with a frontal face arranged oppositely to the surface of the magnetic data carrier as disc or tape and with a holdin surface carrying the head unit. The ferromagnetic thin laye of the head unit constitutes a magnetic circuit comprising an air gap arranged at the frontal face and a straight element with a one or more coil wire around in the rear part of the substrp*e. The coil serves for generating a reading current during forwarding data from the carrier or for involving changes of magnetic flux in order to alter the state of the magnetic elements of the carrier surface. The main disadvantage of these magnetic heads follows from the presence of the air gap which is unavoidable necessary for analogouos signal transmittance: the magnetic flux is divided by the air gap into two parts; the greater one " is transmitted by the magnetic circuit to the coil and the remaining part, estimated mostly for about 40 % is dissipated in the air gap without any positive effect. However, different mechanical forms of the air gap can be helpful in diminishing the flux losses, for example by shortening the length of the parallel parts limiting the air gap from two sides. This makes the production sophisticated. The described structure of the magnetic circuit involves the second main problem: the magnetic head must be equipped with a coil around what causes lots of technological problems especially difficult to solve in little dimension of the integrated magnetic heads. Of course, by convenient masques this is a problem which can be solved, however, by increasing costs. The flux dissipa¬ tion can be limited also by using a material of high magnetic permeability which provides to limiting the high-frequency parameters. This means that the frequency modulated signals can not be registrated with a speed desired in many cases by magnetic heads comprising such materials. Summary of the invention The invention is aimed for avoiding the above mentioned disadvantages. The invention is based on the perception that the use of a construction elaborated for processing analogu signals and comprising a coil for inducating a voltage or a magnetic flux is not necessary in the digital data process technics, because the principle of digital processing rende the use of very simple solutions for storing and reading information possible. The basis of the invention is the physical law of induction: a voltage is induced by a magnet field generated by moved magnetic elements or the field thereof can be influenced by a voltage generating a magnetic field. The object of the invention is therefore to elaborate a magnetic head in integrated form for making use of the above perception which can be performed by a simple technology, characterized by a low place requirement and is fully capable of carrying out the operations necessary when storing or reading information. Hence, the object of the invention is an integrated magnetic head comprising a substrate with a frontal face arranged oppositely to a magnetic data carrier and with a holding surface arranged perpendicularly to the frontal face, a had unit made in form of a layer with ferromagnetic element on the holding surface and two input/output terminals, wherein according to the invention the head unit includes a frontal stripe, i.e. a fl t element being thin in comparison to the width arranged at the frontal face and connected electrically to the input/output terminals, wherein the frontal stripe constitutes a conductor without air gap. The length of the frontal stripe is generally very great in comparison to its thickness, this follows from the working conditions. The frontal stripe can be connected to the input/ put terminals by means of a two-branch rear part, whereby the conditions of connecting the magnetic head to outer units can be improved. According to the practice the best working condi¬ tions of the proposed magnetic head can be reached when the frontal st pe is arranged with one of its longitudinal edge exactly in the plane of the frontal face, it is a flat straight conductor characterized by thickness in range 0,1 to 1 Um and width in range 1 to 50 /Urn. The frontal stripe can be made of a ferromagnetic material being a relatively good conductor, e.g. nickel, and of another ferromagnetic material with lower conductivity as iron, as well. The ferromagnetic frontal stripe can be covered by a layer of metal of high conductivity, as aluminium, silver, copper or gold. This ' covering layer is generally thinner than the frontal stripe. This embodiment is very simple in the production. Another very advantageous embodiment of the invented integrated magnetic head comprises a lower layer implemented into the substrate and an upper " layer with the frontal stripe arranged therebetween, both layers being made of a ferromagnetic material wherein the frontal stripe consists of a metal of high electric conductivity. This is a sandwich-type structure with an preferably non-ferroma netic middle part, wherein the materials can be advantageously selected according to the requirements of the given construction and destination. According to another proposed feature, for facilitating the closing of the flux the upper and the lower layers should be made with a thickness at least five times greater than that of the frontal stripe and the upper and the lower layers extend pe rpendicularly to the frontal face for a distance advantageously at least ten times greater than the thickness of the frontal stripe, whereby the way of the magnetic flux can be closed yet easier than in the previous embodiments with upper and lawer layers. The upper and lower layers can be produced by the means of usual vacuum technology methods, however, they can be consisted of amorphous metal, too. They can be separated from the frontal stripe by an insulating layer, if desired. The preferred electric conductivity of the fronta stripe is at least sometimes, with a magnitude higher than that of the ferromagnetic materials used around. The upper and lower layer are advantageously at least as wide as the frontal stripe. The main advantages of the proposed magnetic head-are the low place requirement, the high effectivity of power transformation and the high sensibility. The magnetic head with a ferromagnetic frontal stripe can be manufactured very easily, the head with sandwich-type structure can be designed on an optimal way according to the given conditions. Brief description of the drawings The invention will be better understood when considered in connection with the attached drawing and some preferred embodiments described with reference to the drawing, wherein Pig. 1 shows in axonometric view one of the preferred embodiments of the invented integrated magnetic head, Pig. 2 shows in axonometric view another preferre embodiment of the proposed integrated magnetic head, Pig. 3 ia the side view of a aeries of magnetic ♦ heads shown in Fig. 1, and Pig. 4 ia the side view of a series of magnetic heads built-up according to Pig. 2. Description of the preferred embodiments The proposed magnetic head as integrated unit (Pigs 1 and 2) comprises a substrate 15 holding a head unit 10 with a ferromagnetic element. The substrate 15 of a unique magnetic head as an independent unit is generally a rectangular shaped body (e.g. cube)made e.g. of silicon onocrystal, ceramics based particularly on alumina, or glass. These materials can be characterized with electric insulating features and high abrasive resistance. The substrate 15 ia a body with a frontal face 14 facing the magnetic data carrier medium as disc or tape lying parallel to the plane thereof and with a holding surface arranged ~ perpendicularly to the frontal face 14 and the data carrier as well. The head unit 10 is arranged on the holding surfac 13 and can be manufactured as usual by means of vacuum technology methods (metal vaporization, sputtering etc.), or like, i.e. by means of methods used in the technology of manufacturing thin layers for electronical equipment. The head unit 10 comprises a frontal stripe 11 which constitutes a continuous straight conductor without air gap.The frontal stripe 11 is arranged at the frontal face 14, generally reaching it with one edge, and advantageously forming a prolongation thereof. The frontal stripe 11 is generally a flat element being thin in comparison to the width. Of course, it can be shaped otherwise, too. Experience shows, however, the most convenient is the fiat and thin stripe with thickness in the range 0,1 to 1 Λ>m and width 1 to 50 ,um. This means, preferably the frontal stripe 11 prolongates the frontal face 14 with a generally straight part of 0,1 to I ,um thickness and covers tha holding surface13 il3 in a part of 1 to 50 ,um width. The frontal stripe 11 as mentioned is made continuous, there is no air gap therein. This practically straight conductor remains during work under the influence or is the source of a timely changing magnetic field whereby information can be transmitted to or form the data carrier. The ends of the frontal stripe II are connected to input/output terminals 1 and 2, whereby the voltage pulses can be conducted to an outer sensing unit or voltage pulses can be forwarded to the frontal stripe 11. The use of the proposed magnetic head can be facilitated by inserting a two-branch rear part 12 connected to the frontal stripe 11, whereby the input/output terminals 1 and 2 can be arranged in a place which is more convenient under given equipment conditions. The two-branch rear part 12 can be made of material different froa that of the frontal stripe 11, if desired, and the only requirement is the relatively high electric conductivity. Usually there are more magnetic heads in a data storing unit of a computer.The substrates of these magnetic heads constitute a continuous body, wherefrom the frontal stripes 11 and the connected parts project only (Pigs 3 and 4). In this case many channels can be used for reading or storing and the frontal faces 14 constitute practically one continuous plane. The frontal stripes 11 are arranged in a common plane, along a common straight line. The integrated magnetic head proposed by the invention can be made in form of many advantageous embodimen wherefrom two basic embodiments seem to be especially preferable. A very simple technology of manufacturing can be selected in the case of the first of these two embodiments (Pigs 1 and 3). In"this case the frontal stripe 11 is a ferromagnetic medium consisting of one of the known ferromagnetic metals or their alloy. The frontal stripe is an advantageously 0,1 to 1 yUm thick and 1 to 50 yUm wide element which can be connected, as mentioned, to a two-branch rear part 12 made of the same metallic material or another material of high electric conductivity. The two-branch rear part 12 forms rather an electric conductor than a closing element for a magnetic circuit. The frontal stripe 11 can t* consisted of nickel which is of relatively high electric conductivity (in comparison to other ferromagnetic metals of the iron group and their alloys) or iron, chromium alloyed iron etc. On the outer surface of the frontal stripe 11 a covering layer 16 can be arranged which is made of a metal of high conductivity, whereby the inner resistance of the head unit 10 is lowered. The metal of high conductivity means in general the aluminiu silver, gold or copper. The thickness of the covering layer 16 amounts up tu 0,3 yθra and it is generally less than the thickness of the frontal stripe 11. The main advantage of the use of the covering layer 16 is that the inner resistance 100 ohm of the frontal stripe 11 made of nickel can be lowered by means of an aluminium cσering layer 16 of 0,2 to 0,3 y»π thickness up to 50 ohm. This results in an improvement of the signal/noise ratio up to 40 %• The aluminium covering layer 16 is especially advantageous to nickel frontal stripe 11 * The substrate 15 consists of, as mentioned, silicon monocrystal or otiier convenient material * The silicon is especially preferred when nickel as ferro¬ magnetic material is used. The optimal choice of the materials used for the substrate 15 and the frontal stripe 11 is a known technological problem wherein the thermal conditions should be taken into account: during registra¬ tion the dissipated energy of the voltage pulses results in increasing temperature of the frontal stripe 11 and the heat is adiabatically transmitted to the substrate 15. This means, the interconnection between these two - elements should be realised by a technology which, of course, after carrying out the preparatory steps required by it, gives in effect a connection of high life duration. Generally the vacuum technology methods are capable of realising connections on the basis of physical adhesive forces wherein the higher but not too high temperature can improve the quality, under the condition that the metal surfaces have been prepared accordingly, they ' contain only a very small amount of impurities. The second of the mentioned two embodiments is optimal under the aspect of material choice wherein it is possible to select the materials according to the destina¬ tion. In this embodiment (Pigs 2 and 4) there are two ferromagnetic parts, namely a lower layer 24 and an upper layer 25 with the frontal stripe 11 therebetween made of metal of high electric conductivity, e.g. of aluminium or copper. Por improving the electric conductivity conductions it is preferred to select a ferromagnetic material of at least one magnitude lower conductivity than the conductivity of the frontal stripe 11. It may be made of e.g. ferrite or chromium alloyed iron etc. Por separating the frontal stripe 11 from the upper and lower layers 24 and 25 it ia preferred to use an insulating layer therebetween which is especially advantageous when ferromagnetic metallic substances of relatively high conductivity form these layers. The frontal stripe is as usual a flat metallic element with preferred thickness 0,1 to 1 yU and width 1 to 50 yUm. The width of the upper and lower layers 24 and 25 may depend on the width of the frontal stripe 11 because it is preferred to select these layers with a width at least equal to that of the frontal stripe 11 which is advantageously covered from both side by the layers mentioned. The width of the upper and lower layers 24 and 25 amount generally from 10 to 500 yUm. In this way the condition is fulfilled that their length and width be at le ast ten times greater than the distance (the width of the gap) between them. This condition follows from the theoretical investigations and ensures minimal losses of the magnetic flux between the ferromagnetic elemen facing one another. (In the known anangement the flux in this direction should be inimalised and not the losses thereof.) The thickness of the upper and the lower layers 24 and 25 amount 1 to 5 yUm, they can be made also of amorphous metal, permalloy, ferrite, chromium alloyed iron, nickel etc. The input/output terminals 1 and 2 can be arranged in this case at the end points of the frontal stripe 11, however, it is more advantageous to arrange a two-branch rear part 12 as shown in Pig. 2. In this embodiment the influence of the heat effects should be taken into account according to the general practice. In an arrangement of more magnetic heads as shown in Pig. 4 the lower layer 24 can be common for a higher number or all of the magnetic heads. In this case the lower layer 24 ia a metal band consisting e.g. of amorphous metal. According to the experience a common layer of this type causes no electric problems during work (e.g. the crasstalk Tsrel shows no increase in comparison to heads with separated lower layers 24). Of course, by selecting convenient materials the described structures of the proposed magnetic head can be realised with other dimensions, too. The problem of design can not be treated in this application and they should be solved in the practice according to the destination of the magnetic head. As for the electro¬ magnetic materials it should be noticed that, as it is well-known, the materials of higher coercivity require pulses of higher level for registrating and during reading provide signals of higher level what makes the data processing more confident. These materials have a higher limit frequency and thereby render higher density of registrating possible. Of course, the higher puls levels provide to higher power losses and result in higher temperatures of the materials used. The materials of lower coercitivity cause a less number of problems in use, work, however, the higher sensibility against noises makes the designer construct more sophisticated electronic structures in order to avoid undesirable false registra¬ tion or reading. The integrated magnetic head according to the invention operates as follows. The magnetic data carrier is forwarded in the direction of the array (Pigs 1 and 2) in parallel to the frontal face 14. The ferromagnetic parts of the magnetic data carrier generate a moving magnetic field. When readin this field generates in the frontal stripe 11 (Pig. l) or in the upper and lower layers 24 and 25 and there¬ between (Pig. 2) a magnetic flux being closed in the material of and around the frontal stripe 11. In this way a voltage is induced which is conducted away by the frontal stripe 11, and this provides an altering electric level in the input/output terminals 1 and 2. During registration the opposite process takes place when the voltage pulses forwarded to the frontal stripe 11 make the magnetic head unit 10 generate a changing magnetic field causing the necessary changes in the ferromagnetic material of the magnetic data carrier forwarded before the frontal face 14. The magnetic head according to the invention transform the main disadvantage of the known solutions into the advantage of generating or .detecting changes with low power consumption because the magnetic flux is exploited fully, practically without losses. The integrated magnetic head according to the invention is generally an element of a longer series of similar magnetic heads arranged at one another. The crosstalk level is minimal and the materials can be selected in an optimal way under convenient conditions of manufacturing. It should be understood that a lot of different advantageous equivalent embodiments can be realised on the basis of the description given above without limiting the scope of protection. Therefore the scope of protection should be determined on the basis of the attached claims and not by the preferred embodiments shown above. The magnetic heads equivalent to those given above will have a structure depending on the field of application and the given circumstances.

Claims: CLAIMS : t 1. Integrated magnetic head, particularly for data storage units, comprising a substrate with a frontal face arranged oppositely to the surface of a magnetic data carrier and with a holding surface perpendicular to the frontal face, a head unit made in form of a layer on the holding surface and two input/output terminals connected electrically to the head unit, wherein the head unit includes a ferromagnetic element, c h a r a c t e r i z e d in that the head unit (10) comprises a frontal stripe (11) arranged along the frontal face (14) and connected electrically to the two input/outpu terminals (l, 2). 2. A magnetic head according to claim 1, wherein the frontal stripe (11) is connected to the input/output terminals (1, 2) by means of a two-branch rear part (12). 3. A magnetic head according to claim 1 or 2, wherein the frontal stripe (11) is a thin layer with a plane of 0,1 to 1 yUm thickness ending at the edge of the frontal face (14) wherein the width of the plane is in the range to 50 yUm. 4. A magnetic head according to any preceding claim, wherein the head unit (10) is a frontal stripe (11) made of ferromagnetic material. 5. A magnetic head according to claim 4, wherein the frontal stripe (11) is covered on its surface separated from the holding surface (13) by a covering layer (16) consisting of a metal of high electric conductivity., particularly, aluminium, gold, copper, silver. 6. A magnetic head according to claim 5, wherein the covering layer (16) has a thickness equal or less than that of the frontal stripe (11). 7. A magnetic head according to any of claims 1 to 3, wherein the head unit (10) comprises a lower layer (24) and an upper layer (25) with the frontal stripe (11) therebetween, both of upper and lower layers (24, 25) made of ferromagnetic material and the frontal stripe (11) constituted by a metallic material of high electric conductivity. 8. A magnetic head according to claim 7, wherein the thickness of the lower layer .(24) and the upper layer (25) is at least five times greater than that of the frontal stripe (11). 9. A magnetic head as claimed in claim 7 or 8, wherein the upper layer (25) and the lower layer (24) extend perpendicular to the frontal face (14) at least ten times longer than the thickness of the frontal stripe (11)covering the frontal stripe (11) over full width. 10. A magnetic head as claimed in any of claims 7 to 9, wherein the lower layer (24) and/or the upper layer (25) ia made of amorphous metal. 11. A magnetic head as claimed in any of claims 7 to 10, wherein the frontal stripe (11) is made of material of electric conductivity at least one magnitude higher than that of the material of the upper layer (25) and the lower layer (24). 12. A magnetic head as claimed in any of claims 7 to 11, wherein the frontal stripe (11) is covered by an insulating layer on at least one of its surfaces facing the upper layer (25) and the lower layer (24).

Inventors: KARMAN PETER, VASS LASZLO, ZSOM GYULA, KARMAN, PETER, VASS, LASZLO, ZSOM, GYULA
Applicants: KARMAN PETER, VASS LASZLO, ZSOM GYULA, KARMAN, PETER, VASS, LASZLO, ZSOM, GYULA
Application year: 1984
Main classification: G11B5
IPC codes: G11B5