DE2329693A1 - ELECTROMAGNETIC CONVERTER WITH EXTINGUISHER ASSEMBLY - Google Patents

Description

Boeblingen, June 7, 1973 heb-oh

Applicant: International Business Machines

Corporation, Armonk, N.Y. 10504

Aiutl. File number: New registration

File number of the applicant: SA 972 006

Electromagnetic converter with an arcing core structure

The invention relates to an electromagnetic transducer with a quenching core structure and, more particularly, to a quenching core arrangement which generates an erasing field which is essentially constant over a current range above a minimum current leading to saturation of the core in the area of the air gap is required.

The use of magnetic heads for recording and reproducing information has gained great importance in the past. the Improvement of the magnetic properties of such magnetic heads has reached a particularly critical stage in that at magnetic recording constantly increases the recording density a recording medium has been increased. Accordingly, will be ongoing Attempts have been made to increase the density of the individual tracks, i.e. the number of tracks per inch or cm across the record sober surface of a magnetizable medium. The track density depends on the width of the information track and demands therefore that the effective gap width of an electromagnetic transducer is kept very small. One way to reduce the gap width results, for example, in a read / write head that has a relatively large gap width and has an erasing agent that Delete the edges of the newly created track immediately after recording. This way only one becomes very effective

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narrow information track recorded and when reading can with A wide track can be read with this converter if the erasing device is switched off during the reading process. The present Invention is therefore directed to a magnetic transducer with improved erasing properties, which over a large Range of extinguishing current amplitude provides a constant extinguishing amplitude.

Recording heads which are also used to erase information tracks have long been known. It must be remembered that when recording a track on a magnetizable medium, the magnetic recording an alignment of the areas of the magnetic recording medium causes and thereby an erasure the information previously recorded on the track. Some procedures and facilities are an example on erasing magnetic records. Erasing a number of tracks at the same time is disclosed in U.S. Patent 2,987,582 mentioned. Erasing the edges of a track by tunnel-like erasing devices of an electromagnetic transducer shows U.S. Patent 3,155,949.

The first mentioned patent shows an erase head with a Number of tooth-like pole pieces for the selective erasure of a number of channels on a magnetizable recording medium. A Erase head of this type extends over the entire width of the record carrier and is used in relation to this record carrier fixedly attached. However, this patent does not show the erasure of edge portions of a previously recorded one Track and would also be for systems with selective access, in which the individual tolerances can add up, because of the arrangement one pole shoe edge per track not applicable.

The second mentioned patent describes an erasing arrangement with a read / write head and one with the read / write head Aligned erase head to erase both edges of the recording track. That from each track after erasing the edges

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however, the recoverable read signal decreases continuously as the current in the erase head is increased. So if at one point the The erasing current is large enough, the entire magnetic recording track is actually erased.

In order to avoid these serious disadvantages, the invention a novel electromagnetic recording head with designed a quenching core, with the help of which the edges of a just recorded information track can be erased immediately after recording by the write head, the transducer providing a quenching field over a large area above the smallest required to saturate the core Current remains uniform in the area of the working gap or air gap height. The arcing core consists of a flexible one Strip of magnetic material with two parallel, spaced-apart legs at both ends of the strip having, this distance corresponding to the desired track width after the deletion process. The core is bent so that the Ends of aes strip are substantially perpendicular to the plane of a first surface of a housing in which the core itself is housed. The ends are kept at a distance from one another, with the first legs forming a first erasing gap Erasing one edge of the information track and the second leg a second erasing gap for erasing the opposite one Form the edge of the information track. Furthermore, means are provided for fastening the core to the housing, the first and hold second leg sections in parallel for a height of the working gap that is less than the length of the legs locked in. These fasteners also maintain the width of the extinguishing gap. This converter can be used with Manufacture at low cost and can be used together with electrical components that have a wide range of options their electrical and magnetic properties, since the same erasing field over a wide range of fluctuations Strength of the extinguishing current is generated.

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The object of the invention is therefore to create a simple, reliable and compact electromagnetic converter for electromagnetic Record information with a simple arcing core arrangement that has a substantially constant erasing field for a large range of variation in the amplitude of the extinguishing current. This new electromagnetic converter is supposed to do this serve to erase the edges of a track that has just been recorded immediately after it has been recorded by the write head.

This is achieved according to the invention in that the erase core consists of a flexible strip of magnetic material, the ends of which each have two parallel legs that are spaced apart from one another, the spacing of which corresponds to the width of the track Deletion of the edges determines that this core is bent over so that the ends of the strip forming the core are flush with the complete the first surface so that the first two legs and the second two legs each have an erasing gap in the first Form surface, wherein the core is assigned a quenching winding, that further the housing in a first section at least a first part of the read / write head core and in a second part at least a second part of the read / write head core and has a cavity for receiving the arcing core structure, that a third housing part for receiving the arcing core is provided and that the erase gap is perpendicular to the track and on the other side of the vertex with respect to the write gap of the read / write head are arranged.

The invention will now be described in more detail using an exemplary embodiment in conjunction with the accompanying drawing. In the drawing shows

Fig. 1 is a plan view of an electromagnetic

Converter according to the invention, together with the new arcing core arrangement;

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Fig. 2 is a sixth sectional view of the in Figure 1 Darge

illustrated transducers along line 2-2 in FIG. 1;

Fig. 3 is a graphic representation of the change in

Signal level of a track as a function of the erase current, which flows through the erase head;

4 shows an enlarged plan view of the gap area

of the electromagnetic transducer according to FIG. 1 in the area of the circle drawn there;

Fig. 5 is a plan view of the erase core in front of its

Installation in the electromagnetic converter and

6 is a side sectional view of the arcing core

along the line 6-6 in Fig. 4 to illustrate the working gap height during the manufacturing process .

In Figures 1 and 2 is in a magnetic recording system an electromagnetic transducer 10 is shown, which by adjusting means 18 with its read / write gap 19 and its erase gaps 26 and 27 can be adjusted to a selected track 17 which is located on a moving magnetizable medium 16. A pressure pad 65 clings the medium to the transducers. The recording medium is shown as a flexible disk which should preferably be used in connection with the present invention, although the electromagnetic transducer also able to work together with a magnetic tape, a magnetic drum or rigid, magnetizable recording media is.

The transducer assembly 10 includes a read / write head 70 and an erase core assembly 30 mounted within a housing 11 is. The C-shaped core 13 of the read / write head 70 has a winding 14 which is fixed in a recess in a first ι

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Part 12 of the housing is housed so that the ends of the C-shaped core 13 with an alignment surface 15 of the first housing part Complete 12.

The L-shaped core 21 of the read / write head 70 is fixedly attached in the same way in a recess in the second housing part 20. The quenching core structure 30 is in a second housing part immediately adjacent to the L-shaped core 21 and around a Wedge piece 23 arranged around, which also determines the working gap height of the extinguishing column. The wedge 23 is in the arcing core assembly 30 inserted and through a beveled mating surface 61 of the second housing section 20 and through a third housing section 60 held. Fasteners 62 hold parts 60 and 20 together and screws 29 hold the part against the alignment surface of part 12. A first housing surface 25 with the three surface segments of the three housing parts 12, 20 and 60 with an outwardly spherical one Surface includes the gap area of the transducer. The smooth, convex shape reduces the friction between the transducer and the moving medium. By having the read / write gap 19 and the erase gaps 46 and 47 on opposite sides of the tallest Point 26 of the surface 25, there is a constant adaptation between the gap and the recording medium. The ones from Areas of the housing that are remote with a gap are offset, as a result of which the rotating recording medium is prevented from being adversely affected will.

The erase core structure 30 contains an erase core 35, which can best be seen from FIG. As can be seen there, the quenching core exists 35 from a one-piece, flexible strip of magnetic material which belongs together at its two ends 36 and 37, respectively Has legs 38 and 40 or legs 39 and 41, respectively. The legs at each end are parallel to each other and become separated from one another by an opening 49, the width of which is essentially corresponds to the desired track width after the deletion process. The core 35 has a between the ends 36 and 37

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Reduced magnetic resistance area 42 with a shoulder 43. The ends of a winding 44 are to be corresponding Out connection terminals which are provided on the housing 20 for connection to an extinguishing current source 45. The flexible magnetic core is first bent and then tempered or tempered in teardrop shape, the ends 36 and 37 at a distance and essentially stand perpendicular to the plane of the first housing surface 25, so that the first legs 38 and 40 a first erasing gap in the first surface for erasing an edge of the track 17 and the second leg 39 and 41 a second erasing gap 47 in the first surface 25 for erasing the opposite edge of the Form lane 17.

The wedge 23 is in the cavity 22 within the second housing part 20 with its tip 24 inserted so that it is at a small distance into the vicinity of the surface 25 extends in the housing 11. The distance between the vertex 24 and the first surface 25 determines the working gap height 48 of the quenching core 35. It was found that the wedge 2 3 spans an angle between 20 and 70 at the apex, which is considered to be sufficient support for the arcing core structure if this is on the surface that determines the working gap height 63 of the housing 20 rests, while at the same time a sufficient working gap leakage flux between the upper legs every extinguishing gap is possible. However, the preferred embodiment results with an angle of 45 °.

The structure of the quenching core 35 is shown in FIGS. One end 37 of the core 35 faces in a corner of the cavity the back of the L-shaped core 21 is attached and bent outward into the cavity 22. After attaching the quenching coil 44 against the shoulder 43, the other end 36 of the quenching core is pressed against the surface of the wedge piece 23 so that the outer end of the core to about half the length of the legs, which is determined by the opening 49, outside the surface 25 extends. A non-magnetic spacer washer 50, preferably

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2329633

made of brass, with two legs 52, which through an opening or a window 51 separated from one another is inserted into the arcing core between the ends 36 and 37, with the legs 52 rest against the corresponding legs 38 and 39. A non-magnetic spacer 55 in the shape of a parallelepiped is inserted laterally between the two first legs and the second legs and thus holds the respective legs of the Extinguishing core aligned parallel and at a distance. The third housing part 60 is attached to the housing part 20 by the surface 61 coincides with a similarly shaped surface of the wedge and the surface 63 which determines the working gap height, which rests against the core end 36, holds the core 35 in the housing with a desired working gap height 48. It must be pointed out that the fork-shaped legs extend within the housing, beyond the apex and onto the wedge surface extend. The gap area of the electromagnetic transducer 10 is shown in FIG. The C-shaped core 13 has a Pole piece 56, which is limited on both sides by non-magnetic, stainless steel laminates 57. A non-magnetic one Spacer 58, which defines the read / write gap 19, separates the pole piece 56 from the pole piece 27 of the L-shaped core 21, the is also limited by non-magnetic laminates 28. The non-magnetic spacer 58 is used prior to attachment of the housing parts 12 and 20 inserted together between the pole pieces. The legs 38 and 39 are applied to the core 13 and laterally held at a distance by a non-magnetic spacer 55. The legs 52 of the spacer 50 prevent the legs 40 and 41 touch the legs 38 and 39, respectively, so that the desired extinguishing gaps 46 and 47, respectively, are retained. Consequently the ends of the strip of magnetic material are substantially perpendicular to the plane of the first surface 25 and the first and second leg sections of the arcing core are kept parallel and spaced apart. To the parts of the arcing core To hold, an epoxy resin 54 is inserted. Alternatively, another spacer (not shown) could be used for separation can be used between core 13 and the parts of the erase head.

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Since the pole piece 27 is wider than the pole piece 56, even in the event of a somewhat imprecise alignment of the pole pieces during assembly, no damage occurs, since the entire edge of the pole piece 56 would still be in the vicinity of a magnetic yoke across the pole piece 27. Also is the spacer 55 is essentially the same width as the pole piece 27 and the outer limits of the arcing core parts are with the outer limits of the stainless steel laminates 28 aligned so that a snug fit and good alignment within the through the mating parts 20 and 60 of the slot formed is ensured.

FIG. 3 shows a diagram in which the size of the signal amplitude of a track of the magnetic medium as a function of the extinguishing current is shown. When a read / write head is excited by a write current of a given magnitude, a signal level becomes recorded in the track 17 in accordance with the read voltage curve 80. This written signal is essentially constant. According to the present invention, the erase heads are always energized when the read / write head is energized for recording to the Erase the edges of the track you just recorded. The curve 85 shows this after erasing the track edges by the novel magnetic head remaining signal. For small values of the erase current, there is initially a decrease in the signal that can be removed from the track. If, however, a minimum erase current is exceeded, the signal level remains essentially constant after the erasure. Of the Magnetic head according to the invention uses an erase current of about 80 mA, as represented by operating point 86. This The operating point is in the straight part of the curve and is greater than the current at point 87, which corresponds to the smallest current, which is required to generate a uniform and constant erasing field. From curve 85 you can see that even if the electrical or magnetic properties of the new electromagnetic transducer or the associated electronic Circuits easily changed, either individually or for a group of magnetic heads manufactured together "; rden,

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despite the fact that the signal remaining after the track edges have been erased would be the same as long as the erase current is beyond point 87, i.e. approximately above 40 mA in the exemplary embodiment. But that means that the dimensions of the individual parts of the converter are reduced and the electrical switching elements for the driver stage for the erase head less strict manufacturing tolerances are required, so that the manufacturing costs can also be greatly reduced without having to accept a reduction in the performance of the head must become.

For the sake of explanation, curve 82 is also shown, which shows the change in signal of a normal tunnel erase head. One can see that with increasing erase current, the signal remaining after erasing the edges continuously decreases in strength and at very high extinguishing current almost reaches the value 0. Since there is no constant signal range here, the characteristics of the electromagnetic transducer consequently extremely sensitive to changes in the operating point, so that the Manufacturing tolerances of each magnetic head must be adhered to particularly precisely.

For the description of the constant erasing process, reference must be made to the fact that the ends of the legs of the erasing head touch the magnetizable recording medium and in the area of the working gap have opposing surfaces over the entire height, which then gradually rise above the working gap diverge to an angle of 45. Accordingly, the magnetic flux penetrating one of the legs meets the smallest Magnetic resistance in a path in the longitudinal direction through the medium across the erasing gap and across the other leg, so that the magnetic flux is essentially along this path. This flow is known as the edge flow or the erase flow. It is exclusively this erasure flow, which causes the tunnel-like erasure of the edges of the track just recorded. Around however, to achieve a constant erase field and to prevent the erase flux from fluctuating in strength, the erase kernel becomes

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driven by a magnetomotive force affecting the recording medium and saturates the area of the pole pieces. Normally the material of an arcing core is not saturated, since it is only it is necessary to generate a field strength of the erasing field in the erasing gap which is above the coercive force of the recording medium lies. Now, once the recording medium is saturated, a reinforcement of the penetrating the core carries magnetic flux contributes very little to the edge-erasing field and the magnetic flux is mainly across each other opposite surfaces of the legs of the quenching core within the working gap area as leakage flux in the gap. A saturation in the working gap area increases the effective gap width between the opposing legs, so that at this point a very high magnetic resistance occurs. This can be seen in FIG. 3 at point 87. Accordingly, each additional will be den Core penetrating flux emanate as stray flux from the legs above the working gap and a path within the quenching core follow. This flow is a pure stray flow. The non-magnetic Wedge 23 does not affect this flow, although it is physically in the path of this flow. Neither the leakage flux in the gap, nor the leakage flux outside the gap, contributes to the extinguishing process and therefore has no influence on the amplitude of the signal recorded on the track.

The quenching core is preferably punched out of an extremely precisely rolled sheet of an iron alloy with high permeability. The dimensions required to manufacture the core depend on the magnetic material used. The spacer defines a relatively large width of the erasing gap of approximately 0.05 mm, so that the erasing process can withstand fluctuations in the height of the working gap is relatively insensitive. Accordingly, the height of the working gap can be between 0.025 and 0.0175 mm vary. The legs of the nucleus that, compared with the body of the core, having a smaller cross-section, are about 1.524 mm long, making a large one Area for the leakage flux in the area of the femoral neck.

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Wear is a very important point in the construction of this magnetic head, since it rests on the magnetizable recording medium during operation and is also intended for this purpose. The housing is made of stainless steel, which is corrosion-resistant and non-magnetic and which reduces the problems resulting from wear between the magnetic head and the recording medium. The spherical dome-shaped outer shape of the housing surface also reduces wear and allows it
closer fitting of the recording medium over the read / write gap and the erase gap.

It has thus been shown that a significantly improved structure of an electromagnetic transducer was created by the invention, in which parts of the legs of the arcing core are kept parallel over the height of a working gap
is smaller than the length of the legs themselves, while the width of the erase gap is kept at a constant value, so that the erase field remains essentially uniform over the smallest current which is required to saturate the core in the region of the
Working gap is required. Since the distance between the writing gap and the erasing gap is very small and the head therefore clings perfectly to the recording medium, it is suitable
the head is an excellent way of recording information
with very high recording density.

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Claims (9)

PATENT CLAIMS Electromagnetic transducer with a read / write head for recording a track of information on itself moving magnetizable recording medium, with an erase core for erasing the edge areas of an information track that has just been recorded and with one of the Read / write head and the erase core carrying housing, which has a first, outwardly directed, spherical, smooth, uninterrupted spherical surface with an apex in the immediate vicinity of the plane of the magnetizable Has medium, and is adjustable for recording on a track, characterized in that the Erase core (30) consists of a flexible strip (35) of magnetic material, the ends (36, 37) of each two parallel legs (38, 39, 40, 44) which are spaced apart from one another and whose spacing is the Width of the track after deletion of the edges determines that this core is bent over so that the ends of the core forming strip flush with the first surface (25) so that the first two legs (38, 40) and the second two legs (39, 41) each form an erasing gap in the first surface (25), the The core is assigned a quenching winding (44) that furthermore the housing (11) in a first section (12) at least a first part (13) of the read / write head core and in a second part (20) at least a second Contains part of the read / write head core (21) and has a cavity (22) for receiving the erase core structure, that a third housing part (60) is provided for receiving the quenching core (35), and that the quenching gaps (46, 47) perpendicular to the track and on the other side of the vertex with respect to the writing gap of the Read / write head are arranged. sa 972,006 309883/0976 2. Converter according to claim 1, characterized in that the first surface (25) of the converter housing is spherical is rounded. 3. Converter according to claim 1 and 2, characterized in that in the second housing part (20) in the cavity (22) a wedge (23) is provided for fastening and fixing the position of the quenching core, the apex of which coincides with a small distance from the first surface (25) in the direction of this, that the bent arcing core adjoins the write head and thus with the two erasing gaps (46, 47) in the immediate vicinity to the writing gap of the writing head and extends over the wedge also that the Legs (38, 40, 39, 41) determine the working gap height, which is smaller than the length of the legs and thereby keep the width of the erase gaps (46, 47) constant, so that the flux field over a wide area above of the current required to saturate the erase core remains substantially uniform. 4. Converter according to claim 3, characterized in that the distance between the apex of the wedge piece (23) and the first surface (25) of the housing determines the height of the working gap. 5. Converter according to claim 1 to 4, characterized in that that the wedge (23) has an apex angle between 20 ° to 70 °. 6. Converter according to claim 1 to 3, characterized in that a non-magnetic spacer disc (50) with two Legs (52) is arranged within the extinguishing column (46, 47) and extends into the area of the bent Part of the arcing core extends. SA 972 006 309883/0978 7. Converter according to claim 1 to 3, characterized in that the quenching core reduced a wider section (42) Has magnetic resistance with a shoulder (43) on which the quenching coil (44) rests. 8. Converter according to claim 1 to 3, characterized in that that between the legs (38, 40; 39, 41) of the quenching core another non-magnetic spacer (55) is inserted that keeps the legs of the core parallel at a distance. 9. Converter according to claim 8, characterized in that a pressure pad for pressing the flexible recording medium (65) is provided. SA972 0O6 309883/0976 Blank page