JPH04178913A - Magnetic head and magnetic recording device - Google Patents

Abstract

PURPOSE:To prevent reduction in reproduction output of a preceding magnetic head when performing helical scanning by allowing an specific amount of wear of each head chip to be different so that a curvature radius in width direction after aging wear is nearly equal in a last magnetic head chip rather than a top magnetic chip. CONSTITUTION:When rotating a rotary cylinder, first a top magnetic head chip 1 which contact a magnetic tape, a middle magnetic head chip 2, and a last magnetic head chip 3 are mounted to a head base 4. When helical scanning is performed by this multi-track magnetic head, change in amount of head projection due to wear of magnetic heads 1 - 3 can be made nearly equal since the top magnetic head 1 has a smaller specific amount of wear than that of succeeding magnetic heads, thus enabling a curvature radius in width direction of magnetic heads 1 - 3 to be nearly equal and contact state of magnetic tape for each magnetic head to be nearly equal. Therefore, reduction in reproduction output of the preceding magnetic head can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic head used in audio equipment, video equipment, computers, etc., and particularly relates to contact between a magnetic head and a magnetic tape used for high signal rate recording and reproduction. The present invention relates to a magnetic head and a magnetic recording device having a structure suitable for maintaining good conditions.

BACKGROUND OF THE INVENTION In magnetic recording devices that perform helical scanning using a rotating head, in recent years, systems that handle wideband signals such as high-quality VTRs and digital VTRs have been actively developed.

In order to record and reproduce broadband signals, multi-track magnetic heads are being researched (for example, Yoda et al.;
3rd Japanese Society of Applied Magnetics Academic Lecture 22pA-15).

In order to perform multi-track recording and playback, it is better to attach multiple heads to one window of a rotating cylinder, and in order to maintain uniform contact with the tape, the protruding shape of the head and the track width direction R should be adjusted. Efforts such as optimization have been made.

The magnetic head chips installed in these devices mainly include bulk type magnetic heads made of ferrite or laminated magnetic heads in which both sides of a magnetic material forming a magnetic path are sandwiched between non-magnetic substrates. ing.

In recent years, the magnetic tapes used in these magnetic recording devices have been made thinner to meet the demand for longer-duration, larger-capacity recording, thereby increasing the length of the magnetic tape that can be stored in a unit volume. is being actively considered. However, when the magnetic tape is made thinner, the stiffness of the magnetic tape decreases in inverse proportion to the cube of the thickness.

Problems to be Solved by the Invention When a multi-track magnetic head such as the one described above is used to record and reproduce information on a thick magnetic tape for short-time recording, the front shape of the head adapts to the thick magnetic tape, and the widthwise direction of the magnetic head changes. The radius of curvature becomes larger. Generally, the pressure on the entry side of the head is greater than the pressure on the exit side due to the deformation of the tape due to the airflow caused by the rotation of the cylinder and the relative movement of the tape head. In particular, in multi-track magnetic heads made of the same material, the amount of wear on the first magnetic head is greater than the amount of wear on the last magnetic head in the direction of rotation of the cylinder. The radius of curvature in the direction is larger than the radius of curvature in the width direction of the rearmost magnetic head. After this, when recording and playing is performed on a thin magnetic tape for long-term recording, the thin magnetic tape becomes
Since the stiffness is small, deformation of the magnetic tape in the width direction becomes large, and contact with the leading magnetic head becomes insufficient. As a result, spacing loss increases, and the reproduction output of the leading magnetic head is lower than that of the succeeding magnetic heads. This is observed as a deterioration of the envelope of the output waveform.

In conventional magnetic heads, attempts were made to improve this phenomenon by reducing the radius of curvature in the width direction of the early magnetic heads.
The shape of this radius of curvature changes greatly as the magnetic head wears, and as the wear progresses, there is a difference in the amount of wear between each head, which causes the radius of curvature of each head to change, making it impossible to obtain essential improvements. I couldn't.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic head and a magnetic recording device that solve the problem of a decrease in the reproduction output of a preceding magnetic head when performing helical scanning using a multi-track magnetic head.

Means for Solving the Problems In order to achieve the above object, the present invention provides a multi-track magnetic head having magnetic head chips adjacent to each other, comprising:
The specific wear amount of each head chip is varied so that the radius of curvature in the width direction after wear over time is approximately the same from the first magnetic head chip to the last magnetic head chip in the rotational direction of the rotating cylinder. It is something.

Generally speaking, when a magnetic tape and a magnetic head slide, the amount of wear on the magnetic head increases as the contact pressure increases. Therefore, when a magnetic tape is slid on a conventional multi-track magnetic head having the same core width, the pressure on the magnetic head normally decreases from the first magnetic head to the last magnetic head. Therefore, the amount of wear on the leading magnetic head increases, and the radius of curvature in the width direction also increases. When helical scanning is performed with the multi-track magnetic head of the present invention, since the leading magnetic head has a smaller specific wear amount than the succeeding magnetic heads, changes in head protrusion amount due to wear of each magnetic head can be made almost equal. Therefore, the radius of curvature in the width direction of each magnetic head can be made almost the same, and the state of contact of the magnetic tape with each magnetic head can be made almost the same. Furthermore, even if wear progresses, the same good head touch is maintained for each head.

Embodiment Hereinafter, a magnetic head according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of an embodiment of a multi-track magnetic head with three magnetic head chips to which the present invention is applied, and FIG. 2 is an enlarged view of the magnetic head chip portion.

The magnetic head is constructed by mounting on a head base 4 a leading magnetic head chip 1, an intermediate magnetic head chip 2, and a rearmost magnetic head chip 3, which first come into contact with the magnetic tape when a rotating cylinder rotates.

The specific wear amount is the volume of wear per unit running time, and is measured by attaching various head materials with the same tip curvature radius and head protrusion on the rotating cylinder of the magnetic recording device used, and running the same magnetic tape for a predetermined period of time. It is determined by dividing the wear volume by the running distance, and is determined by the magnetic tape and magnetic head material used in each magnetic recording device. The wear volume was determined by measuring the shape before and after the wear test with a stylus type surface roughness meter and calculating the volume difference.

In the examples, the specific wear amount is calculated as the wear volume after running a commercially available 5-VH3 videotape for 100 hours using a 5-VH3 type VTR deck with various head materials installed in the same shape, and calculating the wear volume by the running distance (running time x relative velocity).

The multi-track magnetic head used in the present invention has a configuration as shown in FIG. 2, for example.

The leading magnetic head chip l has a specific wear amount of 5.0 x io-
The intermediate magnetic head chip 2 is made of Mn-Zn ferrite with a specific wear amount of 7.2 Magnesium-based ceramic material (N
This is a magnetic head chip with a laminated structure sandwiched between non-magnetic substrates made of tO-TiO□-MgO system), and the last magnetic head chip 3 has a specific wear amount of 10XIO-"n on both sides of the magnetic material forming the magnetic path. This is a magnetic head chip with a laminated structure sandwiched between nonmagnetic substrates made of a barium titanate ceramic material (Tie, -BaO system).

FIG. 3 shows an embodiment of a magnetic recording device according to the present invention.

In the figure, the magnetic tape 24, which slides in contact with the inclined posts 25, 27, the rotating upper cylinder 28, and the fixed lower cylinder 26 and moves in the direction of the arrow, is partially turned to the side for illustration purposes.

In a conventional multi-track magnetic head made of the same material, the leading magnetic head 1 is connected to the following magnetic heads 2,
Since the contact pressure is stronger than that of 3, wear progresses and the radius of curvature in the width direction increases. For this reason, when a thin magnetic tape is recorded or reproduced after running on a thick magnetic tape, the contact condition of the leading magnetic head becomes poor and the reproduction output decreases. The envelope of this playback output is shown in Figure 4 (A), (B), (
Shown in C). In this way, the envelope of the magnetic head on the entry side with respect to the running direction is severely collapsed.In contrast, in the magnetic head of the present invention, the specific wear amount increases from the first magnetic head 1 to the last magnetic head 3. Therefore, changes in the amount of head protrusion due to wear are approximately equal, and the radii of curvature in the directions of each head are also approximately equal. Therefore, good output characteristics can be obtained even when recording and reproducing thin magnetic tapes. The envelope of this playback output is shown in Figure 5 (A).
.

Shown in (B) and (C). As is clear from FIGS. 4 and 5, the structure of the magnetic head of the present invention provides a uniform envelope output. Furthermore, since the changes in the head protrusion amount due to wear of each head are approximately equal, the running time until the gap depth opens is also approximately equal, resulting in a head configuration in which each head chip has a uniform lifespan.

Also, the following configuration is possible. The three magnetic head chips each have a structure in which a magnetic body forming a magnetic path is sandwiched between non-magnetic substrates on both sides,
The substrate of the first magnetic head chip has a specific wear amount of 8.3X1
0-”% magnesium titanate ceramic material (
The substrate of the central magnetic head chip is made of a calcium titanate ceramic material (TiO□-CaO system) with a specific wear amount of 15 x 10-'' rrf.
The substrate of the last magnetic head chip has a specific wear amount of 19xl.
A structure suitable for the present invention is also obtained when a manganese nickelate-based ceramic material (N i 0-Mn0-based) of O-" rrf is used.

Also, the following configuration is possible. A bulk type dummy head chip made of Mn-Zn ferrite is provided in front of the leading magnetic head chip of the multi-track magnetic head.
The present invention also applies to the subsequent magnetic head chip, which is a magnetic head chip having a structure in which both sides of a magnetic material forming a magnetic path are sandwiched between non-magnetic substrates having a higher specific wear amount than Mn-Zn ferrite. It becomes a suitable structure.

It is also known that the abrasion resistance of single crystal materials differs depending on the position. Therefore, by changing both positions of the single crystal ferrite used in the bulk magnetic head or both positions of the substrate material, magnetic head chips having different specific wear amounts may be manufactured, and a multi-track magnetic head may be manufactured.

The embodiment described above is based on the case where there are three magnetic head chips, but the magnetic head of this configuration can also be applied in a configuration where four or more magnetic head chips are installed in one head installation window of the cylinder. Needless to say, it shows the effect of

The magnetic head of this structure can be manufactured by a method other than the above, and by having a structure in which the specific wear amount increases sequentially from the leading magnetic head to the rearmost magnetic head in the rotational direction of the cylinder, the present invention can be manufactured. effect can be obtained.

It goes without saying that the magnetic head of this structure can provide similar effects not only to multi-track magnetic heads with a laminated structure, but also to bulk type ferrite heads and metal-in-gap structure heads.

In addition, the magnetic head of this structure is applicable not only to magnetic recording devices using rotating cylinders, but also to structures in which a rotating head rotates between two fixed cylinders, or structures in which a magnetic head is fixed and a magnetic medium slides at high speed. It is obvious that similar effects can be obtained with multi-track magnetic heads used in .

Effects of the Invention As is clear from the above explanation, the magnetic head of the present invention has the following advantages:
By using a multi-track magnetic head in which the first head chip has a larger specific wear amount than the last head chip, good contact between the magnetic head and the magnetic tape is always maintained, and the playback output due to spacing loss is reduced. The structure prevents the envelope from collapsing.

Moreover, even if the head wear progresses, a good head front shape is maintained, and it has extremely high industrial utility value.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a magnetic head (before coil winding) in an embodiment of the present invention, FIG. 2 is an enlarged view of the head chip portion,
FIG. 3 is a perspective view of a main part of a magnetic recording apparatus using the present invention, FIG. 4 is a reproduction output envelope waveform diagram of a comparative example, and FIG. 5 is a reproduction output envelope waveform diagram of the present invention. 1...Top magnetic head chip, 2...
・Two steps to the middle magnetic field, 3... the last magnetic head chip. Name of agent: Patent attorney Akira Okaji and 2 others.
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Claims (5)

[Claims] (1) A multi-track magnetic head that has three or more magnetic head chips adjacent to each other in one mounting window of a rotating cylinder, in which the magnetic head chips from the first magnetic head chip to the last magnetic head chip in the rotational direction of the rotating cylinder A magnetic head characterized in that each head chip has a different specific wear amount so that the radius of curvature in the width direction after wear over the head chips over time is approximately the same. (2) The leading magnetic head chip is a bulk type magnetic head chip made of ferrite, and the following magnetic head chips have a structure in which both sides of a magnetic material forming a magnetic path are sandwiched between non-magnetic substrates. 2. A magnetic head according to claim 1, wherein a specific wear amount of said non-magnetic substrate is greater than a specific wear amount of said ferrite. (3) A magnetic head chip has a structure in which a magnetic body forming a magnetic path is sandwiched between non-magnetic substrates on both sides, and the specific wear amount of the non-magnetic substrate is lower than that of the leading magnetic head chip. 2. The magnetic head according to claim 1, wherein the magnetic head gradually increases in size toward the last magnetic head chip. (4) A magnetic head having a structure in which the leading magnetic head chip is a dummy head made of ferrite, and the following magnetic head chips have a structure in which both sides of a magnetic body forming a magnetic path are sandwiched between non-magnetic substrates. 2. The magnetic head according to claim 1, wherein the magnetic head is a chip, and the specific wear amount of the nonmagnetic substrate is larger than the specific wear amount of the ferrite. (5) A magnetic recording device using a multi-track magnetic head having three or more magnetic heads in one mounting window of a rotating cylinder, using the magnetic head according to any one of claims 1 to 4. A magnetic recording device characterized by: