DE2341773A1 - MAGNETIC HEAD ARRANGEMENT - Google Patents

Description

It 2584

SONY CORPORATION Tokyo / Japan

Magnetic head assembly

The invention relates generally to a magnetic head assembly and in particular a magnetic head arrangement for recording and / or reproducing a signal on and / or from a rotating flexible magnetic recording sheet.

A device that allows magnetic recording and / or Playback on and / or from a rotating flexible magnetic film with a magnetic head is performed known. In such an apparatus, the magnetic head protrudes from the surface of rotation of the magnetic recording sheet to maintain a small gap between the magnetic head and the magnetic recording sheet. Due to the collision between the magnetic head and the magnetic recording sheet, in the prior art however, a standing wave is generated on the magnetic recording sheet, so that it is impossible to obtain a small To maintain a gap between the magnetic head and the magnetic recording sheet.

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. In US Pat. No. 3,405,405, a method is described in which an air nozzle is provided and the air jet is the Air nozzle is controlled to maintain the small gap. However, this procedure requires a very complicated structure and cannot prevent the above-mentioned standing wave formation.

The invention is based on the object of eliminating this disadvantage. The invention provides a magnetic head assembly created, which consists of a magnetic head and a special shape of a slider that the Magnetic head wears.

Since the magnetic head of the magnetic head assembly according to the invention lightly touches the flexible magnetic sheet, it is possible to achieve a high recording density and therefore the arrangement is according to the invention particularly suitable for video signal recording.

In the following description, the term "contact" means that there is an air bearing between the surface of the Magnetic head and the flexible magnetic recording sheet is formed and the magnetic head only the upper part touches the web surface of the flexible recording film.

The invention also provides an improved magnetic recording apparatus using a flexible one Slide created that video signal storage can perform.

The invention is explained below with reference to FIGS. 1 to 21, for example. It shows:

Figure 1 shows a cross section of a known magnetic film device,

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FIG. 2 is a plan view of the magnetic film used in the device shown in FIG. 1, from which the standing waves generated on the magnetic film emerge.

Figure 3 is a plan view of an example of the magnetic head assembly according to the invention;

FIG. 4 shows a section along the line A-A in FIG. 3,

FIG. 5 is a side view, partly in section, showing the mounting of the magnetic head assembly of FIG Invention emerges,

Figure 6 is a cross-section of a portion of the flexible sheet and a slider of the magnetic head assembly as well as a diagram showing the air pressure on the flexible film,

FIG. 7 shows a representation similar to FIG. 6, but with a differently shaped slider,

FIG. 8 is a plan view of part of the flexible film from which the standing wave formed thereon emerges, when the magnetic head assembly of the invention is used,

Fig. 9 is a graph showing the relationship between the inclination angle of the slider and a work area it appears

Figure 10 to 13 diagrams showing measured results

the arrangement of the invention or the relationship

emerge between the working area and the width of the groove,

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FIG. 14 is a diagram showing the relationship between the normalized working area and the depth difference the groove emerges,

FIG. 15 is a side view of part of the slider, which is used to explain the diagram of FIG is used,

Figure 16 is a side view of another example of the glider,

FIG. 17 is a diagram showing the length of the slider and the contact speed between the flexible film and the magnetic head, and

Tigur 18 to 21 diagrams showing further examples of the magnetic head assembly of the invention.

For a better understanding of the invention, a magnetic recording device will first be described with reference to FIGS described with a flexible film. In the figures, 1 denotes a flexible magnetic recording film, which is attached to a shaft 2 of a motor M which is rotated at a certain speed. Opposite the lower side or the magnetic side of the film 1 is a disk-like back plate 3 in one arranged at a predetermined distance. The back plate 3 has an opening 4 in which a magnetic head 5 is arranged. If a spiral magnetic track or several coaxial circular magnetic tracks on the film 1 are formed, the head 5 is movable in the radial direction of the film 1.

4 G 9 a O 3/1 1 3

When the film 1 is rotated, an even tension is applied to the film 1 due to the centrifugal force caused by the rotation, and between the film 1 and the back plate 3 is an air flow is generated and therefore the sheet 1 is brought into a stationary state. When the head is 5 up protrudes beyond the rotating surface of the film 1 by a suitable length, the gap between the film 1 and the Head 5 is reduced so that a short wavelength signal can be recorded and / or reproduced. Here reduces the flexibility of the film 1, the gap between the film 1 and the head 5 in that the Foil is pressed towards the head, but due to the strong collision between the foil 1 and the Head 5 a standing wave IA is generated near the part of the film 1 where it touches the head 5 and therefore the outer edge IB of the film 1 is subjected to a wave movement. As a result, the contact of the film 1 with the head 5 near the gap of the head 5 unstable. " Because of this, it is necessary to head this far to protrude upwards until the standing wave IA is suppressed by the flexibility of the film 1. However, it is quite difficult to make the head 5 protrude a suitable distance, or the distance around which the head 5 protrudes relative to the rotating surface of the film 1, and also the working area becomes narrow.

3 and 4 show the magnetic head arrangement according to of the invention, According to the invention, a slider 6 is provided which as a whole substantially has the shape of a rectangular plate and is provided with a chamfer such that its top end portion 61 in thickness becomes smaller towards the top. A groove 62 is on the slider 6 in the width direction near the rear End of the end portion 61 is formed. With the one shown

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For example, a recess 63 is formed in the slider 6 along its center line from the end part 61 to the center and the head 5 made of ferrite, for example, is disposed in the recess 63. Here are the Cores 51 and 52 of the head 5 arranged so that they are touched in the longitudinal direction of the recess 6 3 and the contact surface of the head 5 is flush with the top of the slider 6 and the top end surface of the head 5 is, for example, flush with the bottom end face of the gutter 62. The slider 6 may be made of ceramic material or low permeability ferrite. As FIG. 5 shows, the slider 6 is in the opening 4 of the back plate 3 is arranged inclined to the head 5. If the head 5 is made of ferrite, the slider should 6 consist of ferrite of low permeability, since the wear is then essentially the same for both.

With such a construction, since the end part 61 is provided with a bevel, it contacts the film 1 not abrupt, and therefore the life of the film 1 is prevented from being shortened and the film from fluctuating is subjected.

As shown by curve 17 in FIG. 6, the pressure of the air flow is j. the one on the slide 1 from the bottom of the slider 6 is exerted forth, in a region 25 corresponding to the end portion 61, positive, but the Air flow, which creates the positive pressure, is diverted through the groove 62, so that the pressure created by the air flow is caused, in a region 26 in which the head 5 is located, becomes sufficiently negative. Hence will the film 1 drawn to the head 5 by the negative pressure? so that a light touch of the film 1 with the Head 5 is caused to perform stable recording and / or reproduction of a short wave signal. In Fig. 7, 7 denotes the direction of rotation of the film 1.

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If the groove 62 is not present, the pressure caused by the air flow will be as shown by the curve 12 in Fig. shows, and the positive pressure generated in a region 23 can push the film 1 partially upwards and then in pass a negative pressure area 24, where the pressure gradient is quite high, to reduce the negative pressure Eliminate so that the force pulling the film 1 towards the head 5 reduces and thereby the gap between the film 1 and the head 5 is enlarged. The device is therefore not suitable for recording a short-wave signal.

In the magnetic head assembly of the invention, the standing wave becomes IA during recording and / or reproduction is generated on the film 1 near the slider 6, as shown in FIG. 8, but, as has been ascertained, no standing Trowel generated on the film 1 at least opposite the slider 6. Therefore, the contact between the film 1 and the head 5 are not disturbed by the standing wave and therefore remains stable in contrast to the prior art and inevitably.

Fig. 9 shows a working area h relative to the thickness of the flexible magnetic recording sheet 1 which is changed will. The diagram of FIG. 9 shows the measured result, where the angle θ between the back plate 3 and the slider 6 shown in Fig. 5 is changed (on the abscissa), and the slider 6 by the Bore 4 of the back plate 3 from a point where electromagnetic conversion is possible to the point at which the electromagnetic conversion becomes impossible (this is the working range indicated on the ordinate using a 5 MHz signal.

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From the above experiment it was found that a flexible film of about 60 to 80 microns thick, when standing the technique cannot be used in the invention, achieving stable recording becomes, and stable recording is possible even without properly positioning the slider 6. If the The work area may be narrow, a flexible sheet about 100 microns thick can be used with the same result will.

10 to 13 are graphs showing results of other measurements of the head assembly according to the invention emerge. In the diagrams of FIGS. 10 to 13, the abscissa indicates the width a of the groove 62 (FIG. 5) and the Ordinate the working area h. In the diagrams, the angle θ is also selected to be -1 °, 0 °, 1 ° and 2 °, respectively and a parameter o (is the taper of the end part 61.

From the above measurements, assuming that a range of 0.1 to 0.2 mm is selected as the working area or height h of the slider 6 or possible fastening tolerance of the slider 6, the width a of the groove 62 0, 1 to 1 mm and the angle of inclination oC of the end part 61 should be 15 to 55 °. However, when the slider 6 is directed downward (Θ - -1 °), the characteristic becomes wide and a width a of 1.5 mm is possible. If the slider 6 is precisely arranged, a width a of 0.1 to 1.5 mm and an angle of inclination oC of 50 to 65 can be used.

The above results are obtained under the condition that the thickness of the flexible sheet is 30 microns, the rotating speed the flexible film relative to the head at 14 m / second (the speed of the motor is 3,600), the depth of the groove to 400 microns and the distance between

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of the film and the back plate can be chosen to be about 0.5 mm.

14 shows a diagram showing the relationship between the normalized working area h ¹ (on the ordinate) of the head and the sliders and a length χ which is the difference between the heights and depths of the groove and its back and front sides is shown, wherein the depth on the left side is smaller by V than on the right side, as shown in FIG. The normalized working area h ^{1 is obtained} in the converted area by changing the difference y, where the working area

Groove

1 is when the width a of the groove 62 is 0.32 mm, the inclination angle o (35 °, the depth h of the groove 62 is 400 microns, and the depth difference V is 0. As Fig. 14 shows, a stable working range is possible itself if the difference ν / is somewhat large, if the depth h of the groove 62 is chosen large enough.

The characteristic of the head assembly in which a horizontal plane is formed at the top of the end portion 61 between its stopper portion and the groove 62 as shown in FIG. 1 is examined by changing the width α of the horizontal plane. The investigation shows that no substantial change in operation is observed when the width ο is less than 100 microns, but when the width cf becomes 150 microns, the output is reduced to about 1/2 to 1/3.

Fig. 17 is a diagram showing the relationship between the length L of the slider 6 and the direction of rotation of the flexible magnetic sheet 1 on the ordinate in millimeters and the contact speed SC of the flexible Slide 1 with the head on the abscissa can be seen in meters / second by choosing the thickness of slide 1 45, 30 and 20 microns is obtained. The numerical examples above relate to preferred values and the

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Recording can of course be carried out with values other than those mentioned above or larger or smaller.

In the example shown, the slider 6 has a rectangular shape, but a slider with a oval, square or circular shape can be used with the same effect when the length of the Foil is chosen for its direction of rotation, as FIG. 17 shows.

When the head 5, which is to be attached to the slider 6, is arranged relative to the slider 6 such that the working gap is about 0.2 to 0.3 mm or more within the outer circumference of the slider 6, a stable operation can be performed.

In the above example, the surface of the slider 6 closes with the contact surface of the head 5 with the flexible film 1 flush. A recording characteristic in which the contact area the head 5 protrudes above the surface of the slider 6; this results in the following: If the contact surface of the head 5 protrudes from the surface of the slider 6 by 0.2 to 0.3 microns, the output signal becomes increased by 2 to 3 dB. When the distance by which it protrudes is gradually increased, the output becomes gradually decreased. If the distance that the contact surface protrudes is 5 to 6 microns, will the output signal is equal to that when the contact surface is flush with the surface of the slider 6, however, the magnetic sheet 1 is badly damaged and therefore becomes unsuitable for practical use. Preferably the distance that the contact surface protrudes is less than 4 microns.

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Figures 18 to 21 show further examples of the invention. In the example of FIG. 18, the end portion 61 is provided with a Provided bevel and has a smaller height, while in the examples of FIGS. 19 and 20, the head 5 according to is displaced in front or in the rear relative to the slider 6. In the example of FIG. 21, instead of the groove 62, the end portion 61 is separated from the slider 6 and the space thus formed is used as an air exhaust groove.

Although not shown, it is possible to move the recess 63 on the slider 6 from its bottom to the top or the recess 63 can be used as an opening for receiving the head 5.

In the invention, the contact pressure between the flexible magnetic sheet 1 and the magnetic head 5 is during

2
of operation 0.1 to 0.5 g / mm so that the magnetic head 5 touches the magnetic sheet 1 lightly. Therefore, even if a thick flexible magnetic sheet is used, stable recording can be achieved. In addition, since the contact pressure between the sheet and the head is small as compared with a video tape, the sheet and the head are less worn, and hence a long life is possible.

In the previous examples, the magnetic head assembly of the invention is arranged under the magnetic sheet, however, it can also be arranged above the film with the same effect.

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Claims (5)

Claims Magnetic head arrangement, characterized by a magnetic head and a slider which supports the magnetic head and which has a flat surface, a chamfer and a groove between the flat surface and the bevel. 2. Magnetic head arrangement according to claim 1, characterized in that that the slider is made of a ceramic material. 3. Magnetic head arrangement according to claim 1, characterized in that the magnetic head made of ferrite and the slider consists of low permeability ferrite. 4. Magnetic head arrangement according to claim 1, characterized in that that the contact surface of the magnetic head is substantially flush with the flat surface of the Glider is formed. 5. Magnetic recorder with a flexible Magnetic sheet and a magnetic head assembly, characterized by a magnetic head, a slider, the the magnetic head carries and which has a flat surface opposite the flexible magnetic film, a bevel and has a groove between the flat surface and the bevel. 409809/1134 Blank page