JPH0793708A - Magnetic head - Google Patents

Abstract

(57) [Summary] [Purpose] Compatible with magnetic tapes of different thicknesses, good envelope output can be obtained even with thin magnetic tapes, and the tape sliding surface Provided is a magnetic head capable of sufficiently securing the strength and wear resistance of a joining member. [Structure] A pair of grooves 10a, 10b along the sliding direction a of the magnetic tape are formed at both ends of the tape sliding surface 9 of the magnetic head 1 in the width direction b, and the depth thereof is The magnetic tape is designed so that the depth at the outlet side position Y is smaller than the depth at the inlet side position X.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention is a video tape recorder.
The present invention relates to a magnetic head equipped in a magnetic recording / reproducing apparatus such as a VTR (VTR), and mainly relates to a magnetic head used in a rotary head type helikyalskian type magnetic recording / reproducing apparatus.

[0002]

2. Description of the Related Art In a rotary head type helikyalskian type magnetic recording / reproducing apparatus, a magnetic head is fixed to a circumferential surface of a cylinder in a state of protruding by several tens of μm, and a magnetic tape is wound around the cylinder at a constant angle. The magnetic head is slid on the magnetic tape by the rotation of, and recording and reproducing are performed. The magnetic head has a tape sliding surface formed in a smooth elliptic curved surface in both the sliding direction and the width direction, and the head gear tape is formed at the center of the tape sliding surface.

With such a magnetic recording / reproducing apparatus, when magnetic tapes having the same magnetic characteristics but different thicknesses are used for recording / reproducing under a constant tape tension, a thin magnetic tape is obtained. In the section A where the tension of the magnetic tape on the front side in the direction of rotation of the cylinder is large, as shown by the broken line (curve -β) in FIG. However, there is a drawback in that the reproduction output decreases.

This is a thick magnetic tape T as shown in FIG.
₁ contacts almost the entire width direction of the tape sliding surface 21 of the magnetic head 20, but the thin magnetic tape T ₂ has a large tape deformation due to a decrease in rigidity as shown in FIG. The tape sliding surface 21 comes into contact with both widthwise end portions 21a and 21b,
It is estimated that the spacing between the magnetic tape and the magnetic head at the position of the gear center 21c, especially the spacing in the section A where the tension of the magnetic tape increases, becomes large. .

Therefore, conventionally, as an improvement on the magnetic tape side, the rigidity of the magnetic tape is increased by using a base film having a high Young's modulus such as polyethylene naphthalate or aromatic polyamide resin. Is being done. However, since the effect is limited, various improvements on the magnetic recording / reproducing apparatus side have been studied.

[0006] As an improvement on this device side, for example, an attempt has been made to reduce the tension of the magnetic tape or to reduce the protrusion amount of the magnetic head on the circumferential surface of the cylinder, but a thin magnetic tape is used. However, the optimum output of the thick magnetic tape is reduced, and there is a problem that the compatibility between the thick magnetic tape and the thin magnetic tape cannot be obtained.

Further, as shown in FIGS. 10 and 11,
Tape sliding surface 31 (4) on the magnetic head 30 (40)
1) Both ends 31a, 31b (41a, 41) in the width direction
It is also known that the chamfered structure of b) reduces the width of the tape sliding surface to reduce the sliding area and increases the surface pressure between the magnetic tape and the magnetic head. However,
According to this method, when the width of the tape sliding surface becomes a certain value or less, there is a problem that the strength of the joining member that regulates the width of the gear tape decreases.

Further, Japanese Patent Laid-Open Nos. 62-192907 and 60-101706 also propose a method of partially narrowing the width of the tape sliding surface. Correspondingly, if the width of the sliding surface is reduced, the contact area with the magnetic tape will be significantly reduced, so if the width is below a certain value, the amount of local wear of the magnetic head will become extremely large. However, there is a problem in the wear resistance of the magnetic head.

[0009]

As described above, in the conventional improved technique, the compatibility between the thick magnetic tape and the thin magnetic tape cannot be obtained, and the tape sliding surface of the magnetic head is not compatible. However, it is difficult to secure the strength and wear resistance of the joining member.

In view of the above circumstances, the present invention is compatible with magnetic tapes having different thicknesses, and a good envelope output can be obtained even with a thin magnetic tape, and a tape slide is also possible. It is an object of the present invention to provide a magnetic head capable of sufficiently securing the strength and wear resistance of the joining member on the moving surface.

[0011]

Means for Solving the Problems The inventors of the present invention have made earnest studies in order to achieve the above-mentioned object. As a result, when a specific groove is formed at a specific position on a tape sliding surface of a magnetic head, it is thin. When a magnetic tape is used, contact at both widthwise ends on the tape sliding surface is prevented, reducing the spacing between the magnetic tape and the magnetic head at the center position of the gear tape. It was discovered that a good envelope output was obtained, and the invention was completed.

That is, according to the present invention, a pair of grooves along the sliding direction of the magnetic tape are provided at both ends of the tape sliding surface in the width direction, and the depth of the groove is at the entrance side of the magnetic tape. The magnetic head is characterized in that it is formed so as to be smaller at the exit side position.

[0013]

[Operation] In this invention, air flows into the grooves formed at both ends of the tape sliding surface in the width direction. Since the depth of the groove is smaller at the outlet side than at the inlet side of the magnetic tape, the inflowing air is extruded to the outside near the outlet side, and this expulsion causes the inside of the running tape. A pressing force from one side is generated. With this pressing force, even when using a thin magnetic tape, the contact of the magnetic tape on both ends in the width direction as in the past is prevented, and the magnetic tape at the center position of the gear tape is prevented. Spacing to and from the magnetic head is reduced, which results in better envelope output.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the magnetic head of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a magnetic head for a VTR of a rotary head type helicopter scan method of the present invention, FIG. 2 is a front view of a tape sliding surface of the magnetic head, and FIG. 3 is a side view of the same. Is the entry position of the magnetic tape,
(B) is the exit position.

1 to 3, a magnetic head 1 comprises a magnetic core half 2A, 2B and a magnetic gear 4 formed of magnetic alloy thin films 3A, 3B arranged on the opposing surfaces of both halves.
It is constituted by a joining member 5 arranged to hold the magnetic gear 4 and a notch is provided in the vicinity of the facing surface of the magnetic gear 4 to regulate the track width 6. Reference numeral 7 is a winding window for winding the coil 8 around the magnetic core halves 2A and 2B.

The magnetic core halves 2A and 2B contain Mn-Zn.
An oxide magnetic material such as a system ferrite is used, and the magnetic alloy thin films 3A and 3B are made of a Fe-Al-Si alloy,
A crystalline or amorphous alloy material having a high saturation magnetic flux density and a high magnetic permeability, such as a Co—Nb—Zr-based amorphous alloy, is used. The joining member 5 is usually made of lead-based glass containing PbO ₂ as a main component.

As the shape of the tape sliding surface 9 of the magnetic head 1, for example, for Hi8 VTR, the length in the sliding direction (that is, the longitudinal direction) is about 1 to 2 mm, and the length in the width direction is 50 mm. Approximately -100 μm, sliding direction arm (curvature radius) is 5-10 mm, width direction arm is 1-2 mm
Is formed into a smooth elliptic curved surface, and the magnetic gear 4 is formed at the center of the tape sliding surface 9.

At both ends of the tape sliding surface 9 in the width direction b, a pair of grooves 10 are formed along the magnetic tape sliding direction a.
a 10b is formed, and the depth thereof is larger than the depth d ₁ at the entrance side position X of the magnetic tape shown in FIG. 3 (A), as shown in FIG. 3 (B). The depth d ₂ at the outlet side position Y of the cup is set to be small. This groove 10a,
The width of 10b is a tape formed by winding a magnetic tape.
In order to prevent damage to the ridge, the thickness is usually 10 μm or less. The depths d ₁ and d ₂ are preferably about 1 to 10 μm, which is less than the depth d ₀ of the magnetic gear tube 4.

The magnetic head having the above-mentioned structure is used for sputtering the magnetic alloy thin film onto the magnetic core half, bonding the magnetic gear part, cutting out the magnetic core, grinding, polishing the tape sliding surface by lapping tape, etc. After a normal magnetic head manufacturing procedure, the specified track width and specified
After making the tape sliding surface of the tape, a pair of grooves are formed on both ends in the width direction of the tape sliding surface by means such as ion milling, rotating grindstone such as slicer, chemical etching, ultrasonic machining, etc. It is produced by

This magnetic head is a rotary head type helicopter scanning VTR (Hi8VTR; Sony CCD-V90).
Equipped with 0), we investigated the spacing between the magnetic tape and the magnetic head. Figure 5 shows a thick magnetic tape (total thickness 13μ
m) and FIG. 6 shows the case where a thin magnetic tape (total thickness 9 μm) is used. In both figures, the solid line (curve-a, curve-c) is the magnetic head and the broken line (curve) of the above-mentioned configuration of this invention. -B, curve-
The magnetic head for comparison has the same configuration as that described above except that d) does not form the grooves 10a and 10b.

As is clear from these figures, when a thick magnetic tape is used, there is almost no difference between the magnetic head having the above-mentioned structure of the present invention and the magnetic head for comparison, but a thin magnetic tape is used. -If a magnetic head for comparison is used,
While the spacing at the center position of the gear is significantly increased due to the contact on both widthwise sides of the tape sliding surface, according to the magnetic head having the above-mentioned structure of the present invention, the spacing at both ends is increased. Contact with the gear is prevented,
Thing is reduced.

When a thin magnetic tape is used, the reproduction output envelope waveform, that is, the envelope output, is examined for the magnetic head having the above-described structure of the present invention and the magnetic head for comparison. The results shown in FIG. 7 were obtained. In the figure, the solid line (curve-α) is the magnetic head having the above-described configuration of the present invention, and the broken line (curve-β) is the magnetic head for comparison.
From this figure, it can be seen that the magnetic head having the above-described structure according to the present invention can prevent a reduction in reproduction output, which is a drawback of the comparative magnetic head.

In the above embodiment, the grooves 10a 10
b is formed from the entrance end to the exit end of the magnetic tape, that is, over the entire tape sliding surface.
As shown in FIG. 5, it may be formed from the entrance end of the magnetic tape to a portion slightly beyond the magnetic gear 4, that is, on a part of the tape sliding surface. can get. Reference numerals in FIG. 4 are the same as those in FIGS.

[0024]

As described above, according to the magnetic head of the present invention, air is caused to flow into a pair of grooves formed at both ends of the tape sliding surface in the width direction, and a pressure output based on the inflow air is produced. By using, good envelope output can be obtained even with a thin magnetic tape, so compatibility between thin magnetic tape and thick magnetic tape is excellent, and the tape sliding surface is also excellent. Since a sufficient width in the width direction can be obtained, there is no fear of causing a problem in the strength and wear resistance of the joining member as in the conventional case.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a magnetic head for a VTR of a rotary head type helicopter scan system of the present invention.

FIG. 2 is a front view of a tape sliding surface of the magnetic head.

FIG. 3 is a side view of the tape sliding surface of the magnetic head,
(A) is the entrance side position of the magnetic tape, and (B) is the exit side position.

FIG. 4 is a front view showing an example in which a pair of grooves on a tape sliding surface are formed differently.

FIG. 5 is a characteristic diagram showing the relationship between the spacing between a thick magnetic tape and a magnetic head and the widthwise displacement of the tape sliding surface.

FIG. 6 is a characteristic diagram showing the relationship between the spacing between a thin magnetic tape and a magnetic head and the displacement of the tape sliding surface in the width direction.

FIG. 7 is a characteristic diagram showing an envelope waveform of reproduction output when a thin magnetic tape is used.

FIG. 8 is a side view showing a contact state between a thick magnetic tape and a tape sliding surface of the conventional magnetic head.

FIG. 9 is a side view showing a contact state between a thin magnetic tape and a tape sliding surface of the conventional magnetic head.

FIG. 10 is a side view showing a state in which both widthwise ends of a tape sliding surface are chamfered as one of conventional magnetic heads.

FIG. 11 is a side view showing, as one of the conventional magnetic heads, a state in which both widthwise end portions of a tape sliding surface are chamfered in a manner different from the above.

[Explanation of symbols]

1 Magnetic head 2A, 2B Magnetic core half 3A, 3B Magnetic alloy thin film 4 Magnetic gear 5 Joining member 9 Tape sliding surface Sliding direction of tape sliding surface (longitudinal direction) Tape sliding Width direction of surface 10a, 10b Pair of grooves X Magnetic tape entry side position Y Magnetic tape exit side position d ₁ Depth of pair of grooves magnetic tape entry side d ₂ Pair of grooves magnetic tape - the depth of the exit side position of the flop d ₀ magnetic Giyatsupu depth solid (curve -a, c, α) magnetic head dashed present invention (curve -b, d, β) the magnetic head T for comparison ₁ thick magnetic tape T ₂ thin magnetic tape

Claims (2)

[Claims] 1. A pair of grooves extending along the sliding direction of the magnetic tape on both ends of the tape sliding surface in the width direction, the depth of which is greater than the entrance side of the magnetic tape on the exit side. A magnetic head characterized in that it is formed so as to become smaller in position. 2. The magnetic head according to claim 1, wherein the magnetic head is used in a rotary head type helical recording / reproducing system.