WO1990003641A1

WO1990003641A1 - Thin-film magnetic head with flat write/read wire-wound coil

Info

Publication number: WO1990003641A1
Application number: PCT/EP1989/000235
Authority: WO
Inventors: Dietrich Stephani
Original assignee: Siemens Aktiengesellschaft
Priority date: 1988-09-19
Filing date: 1989-03-07
Publication date: 1990-04-05
Also published as: DE3831803C2; DE3831803A1

Abstract

A thin-film magnetic head composed of layers contains a conductor which conducts the magnetic flux. The conductor comprises two magnetic arms with end pieces which form successive magnetic poles and delimit a space beyond the region of these end pieces through which a flat, single- or multi-layered write/read wire-wound coil extends. To ensure minimal losses from the coil, in the apical region (S) of the coil (17) facing the end pieces (10, 11) the width (Ba? to Bi?) of the conducting track (18) from other external coils (17a? to 17i?) is greater that than from similar internal coils (17j? to 17p?).

Description

Thin film magnetic head with a flat read / write coil winding

The invention relates to a thin-film magnetic head with a layered structure, which is arranged on the back of an aerodynamically guided over a recording medium, non-magnetic missile and one magnetic

Contains flux leading guide body with two magnetic legs that

form magnetic poles with the end pieces facing the recording medium, which are arranged one behind the other in relation to the relative direction of movement of the head and the recording medium and are spaced apart in the region of the end pieces by a gap of small width,

such as

- delimit a space outside the area of their end pieces, through which a flat read / write coil winding with at least one layer of a plurality of enveloping turns of at least one conductor track extends.

A corresponding magnetic head goes e.g. from the publication "IBM Disk Storage Technology", February 1980, pages 6 to 9 (cf. also EP-A-0 012 912).

The principle of a longitudinal (horizontal) or vertical (vertical) magnetization for storing data in corresponding, in particular disk-shaped recording media is generally known. Thin-film magnetic heads to be used for these types of magnetization generally have a guide body made of magnetizable material for guiding the magnetic flux, which has two shapes with a shape similar to a ring shape. These magnetic legs form on the End pieces facing recording medium from magnetic poles, which are arranged one behind the other as seen in the relative movement direction of the head with respect to the recording medium, with a narrow gap being formed between the end pieces. Outside the area of the end pieces, the magnetic legs delimit a space which is correspondingly widened due to an increase in the mutual distance between the magnetic legs. A flat one extends through this space

Multi-turn read / write coil winding. The magnetic head known from the publication mentioned at the beginning also shows a corresponding structure. This magnetic head should be arranged on the back of a non-magnetic substrate, which is designed as a missile, which is to be aerodynamically guided over the recording medium (see also e.g. EP-A-0 137 051).

The read / write coil winding of the known magnetic head contains 8 mutually enclosing turns, which can also be created using thin-film technology as a flat conductor track. In addition to a constant conductor path thickness, these windings also have approximately the same width in the area between the magnetic legs. In addition, on the side of the winding facing away from the recording medium, the width of the individual turns is at least approximately the same. However, since the individual turns have different lengths, the resistance of the individual turns is correspondingly different. In other words, in the known winding, the resistance of an outer turn is greater than the resistance of an inner turn enclosed by it.

Magnetic heads of this type are to be used primarily for data storage systems which enable a high recording density. Such data storage systems work in particular on the principle of vertical magnetization. It can now be seen that as the recording density increases, the read voltage on the known write / read coil winding drops. It is therefore endeavored to increase the number of turns. However, this is only possible to a limited extent because the magnetic head is arranged on the flight skid of an aerodynamically guided missile, the width of which is only about 500 μm. In practice, therefore, only about 16 turns can be accommodated in one coil level. Usual read / write amplifiers allow maximum write currents of approx. 200 mApp for a given supply voltage. Ultimately, however, the resistance of the coil winding is responsible for the losses actually occurring and also for the known resistance noise of the magnetic head. The object of the present invention is therefore to design the magnetic head of the type mentioned at the outset in such a way that the resistance of the write / read coil winding becomes as low as possible for a given dimensioning of the space formed between the magnetic legs and for a given number of turns.

This object is achieved according to the invention in that in the apex area of the write / read coil winding facing the end pieces of the magnetic legs, the conductor track of turns lying further outside has a greater width than turns which lie comparatively further inside.

The advantages associated with this configuration of the magnetic head can be seen, in particular, in the fact that the total resistance of the write / read coil winding can be minimized for a given number of turns by providing a correspondingly larger cross section of electrically conductive material for the turns lying further out with a longer conductor track length Is made available as for turns lying further inside with a smaller track length. The minimization of the total resistance which can thus be achieved also results in a corresponding reduction in the resistance noise. Advantageous refinements of the magnetic head according to the invention emerge from the subclaims.

To further explain the invention, reference is made below to the drawing, in which FIG. 1 schematically illustrates a magnetic head according to the invention. Figure 2 also shows schematically the read / write coil winding of this magnetic head. In the figures, matching parts are provided with the same reference symbols. In the case of the thin-film magnetic head for writing and reading, which is only partially illustrated as a longitudinal section in FIG. A-0 012 912 or the

EP-A-0 150 372). The head, generally designated 2 in the figure, is deposited on the flat side of a substrate 3 using known thin-film technology. This flat side forms in particular the back of a runner of a customary element, referred to as a missile, which is not shown in the figure. This element and thus the magnetic head 2 are thus to be guided aerodynamically along a track relative to a recording medium M known per se at a low flying height f of, for example, less than 0.2 μm. The direction of movement relative to the head of the recording medium rotating, for example, underneath this is indicated by an arrowed line denoted by v. The recording medium, in particular a magnetic storage disk, has a storage layer 4 which is selected accordingly the magnetization principle can be described with the head and read out.

The magnetic head 2 contains a ring head-like guide body 6 which guides the magnetic flux and has two magnetic legs 7 and 8. These legs are largely and in particular in the region of their end pieces 10 and 11 facing the recording medium M oriented at least approximately perpendicular to the surface of the recording medium and form a magnetic pole there P1 or P2 off. These end pieces are understood to mean the end of a magnetic leg which has at least largely uniform transverse expansion or thickness and runs approximately parallel to the other end piece. Between the two poles P1 and P2 there is an air gap 12 with an advantageously small longitudinal, i.e. width g of less than 1 μm, in particular less than 0.3 μm, pointing in the direction of movement v. The distance between the two is in a central region 13 of the ring head-like guide body 6

Magnetic limbs 7 and 8 are extended in relation to this gap width g, for example by the magnetic limb 8, which is rearward with respect to the direction of movement v, leading in this area to a larger distance a with respect to the front, just-formed, magnetic limb 7 facing substrate 3. Outside of this guide body region 13, on the side of the guide body 6 facing away from the recording medium M, the magnetic leg 8 is attached in a known manner to the magnetic leg 7 in a connecting region 14, so that the ring-head-like shape of the guide body 6 then results. A flat coil winding 17 extends through the intermediate space 16 thus present between the two magnetic legs 7 and 8 in the central guide body region 13, with which both the write and the read function can be carried out. This coil winding, which is only indicated in the figure, is intended to be the same as the whole Magnetic head can be created using thin-film technology. Their design can be seen in particular from the supervision shown in FIG. 2. As can be seen in FIG. 2, the read / write coil winding 17 is formed by a single conductor track 18 with an at least approximately constant thickness D. This conductor track is arranged like a snail shell to form several mutually enclosing turns. At least 8 turns are advantageously provided. According to the illustrated embodiment, the winding 17 has sixteen turns with

17 _a to 17 _p are numbered from the outside in. A turn is understood to mean a single revolution of the conductor track 18 around the connection region 14 of the guide body 6.

The read / write coil winding 17 should be designed so that the resistance of each of its turns 17 _a to 17 _{p is} at least approximately in the same order of magnitude, so that the total resistance of the coil winding can be kept to a minimum. For this purpose, according to the invention it is provided that in the apex region on the side of the winding 17 facing the end pieces 10 and 11 of the magnetic legs 7 and 8, ie in the region of the intermediate space 16, the width B of the conductor track is larger on the outside than on the inside. In the figure, the conductor track widths B assigned to the individual turns are provided with the indices of the corresponding turns. That is, in the apex region denoted by S in the figure and indicated by a dashed line, the outermost turn 17a closest to the end pieces 10 and 11 has the largest interconnect width B _a , while the innermost turn 17 facing the connection area 14 has the smallest interconnect width B _p has. For the turns 17 _b to 17 in between, the conductor track width need not necessarily decrease continuously from the outside inwards; but it can also be one gradual acceptance may be provided. For example, according to the illustrated embodiment, the sieves. innermost windings 17 _j to 17 _{p have} approximately the same conductor track width B _p , while towards the outside the width of the windings 17 _i to 17 _a lying further outside increases. In any case, however, as can be seen from the figure, each turn has the smallest width of the conductor track on its side facing the end pieces 10 and 11. The respective conductor track width B is understood to mean the extent of the conductor track 18 transverse to the direction of current flow and perpendicular to the thickness D of the individual turns. Since, for example, the further inside turn 17 _{o has} a substantially shorter total length of its conductor track than, for example, the further outside turn 17 _b , a smaller conductor cross section is required for the turn 17 _o and thus - assuming an approximately constant thickness D - a correspondingly smaller one Conductor width B _o in the space 16 than for the winding 17 _b with the comparatively greater total length of its conductor. For the innermost turn 17 _p and the outermost turn 17 _a , the dimensioning rule according to the invention for the conductor track width cannot generally be completely fulfilled, since these turns merge at their ends into relatively wide contact areas 20 and 21, respectively. These areas are to be connected with discrete connection conductors for the read / write coil winding.

According to the illustrated embodiment, it was assumed that the read / write coil winding is formed in one layer. If necessary, however, a multi-layer embodiment can also be provided, in which the inventive dimensioning of the individual conductor track widths B is provided in each individual layer. The individual layers are then expediently interconnected at their contact surfaces 20 and 21 to form the read / write coil winding.

Claims

1. A thin-film magnetic head with a layered structure, which is arranged on the back of a non-magnetic missile to be aerodynamically guided over a recording medium and contains a guide body with two magnetic legs that guides the magnetic flux

- With the recording medium facing end pieces form magnetic poles, which are arranged in relation to the relative direction of movement of the head and the recording medium one behind the other and are spaced in the area of the end pieces by a gap of small width,

such as

- Be outside the area of their end pieces, a space through which a flat read / write coil winding with at least one layer of several surrounding turns extends at least one conductor track, d a d u r c h g e k e n n z e i c h n e t that

in the apex region (S) of the write / read coil winding (17) facing the end pieces (10, 11) of the magnetic legs (7, 8), the conductor track (18) of turns (17 _a to 17 _i ) located further out has a larger one Width (B _a to B _i ) has turns that are comparatively further inward (17 _j to 17 _p ).

2. Magnetic head according to claim 1, so that the read / write coil winding (17) forming conductor track (18) has an at least approximately constant thickness (D).

3. Magnetic head according to claim 1 or 2, so that the write / read coil winding (17) is formed in one layer.

4. Magnetic head according to one of claims 1 to 3 characterized by the fact that the writing /

Reading coil winding (17) has at least 8 Wincuncer, (17 _a to 17 _p ).

5. Magnetkcpf according to one of claims 1 to 4, d ad characterized in that each of the windings (17 _a to 17 _p ) in the apex area (S) of the write-Z

Reading coil winding (17) its smallest width (B _a to B _p )

Has conductor track (18).

6. Magnetic head according to one of claims 1 to 5, characterized in that some of the windings located further inside (17 _j to 17 _p ) have an at least largely the same width (B _p ) of the conductor track (18).

7. Magnetic head according to one of claims 1 to 6, characterized in that in at least some of the turns lying further out (17 _j to 17 _a ) the width (B. to B _a ) of the conductor track (18) increases continuously from the inside to the outside.

8. Magnetic head according to one of claims 1 to 7, characterized in that the outermost and innermost turns (17 _a and 17 _p ) are widened at the ends of the write-Z reading coil winding (17) to contact surfaces (20 and 21) .

9. Magnetic head according to claim 8, d a d u r c h g e k e n n e e c h n e t that at least two layers with turns of conductor tracks are provided for the read / write coil winding and that the turns of the two layers are interconnected at the contact surfaces to the read / write coil winding.