JPH05334637A - Magnetic head - Google Patents

Abstract

PURPOSE:To provide the magnetic head with which the height of the head mounted to the rotary cylinder of a magnetic recording and reproducing device constituted by using the rotary cylinder is not changed with lapse of time by mechanical vibration and temp. CONSTITUTION:Two or more pieces of parallel grooves 5 are formed in the direction perpendicular to the radius of the cylinder near the part of a head base 4 mounted to the upper cylinder 1 where a head chip 3 is stuck. The part between these parallel grooves 5 is irradiated with a laser beam so that the head base 4 is deformed by as much as a prescribed quantity by welding deformation. The depth of the parallel grooves 5 is specified to 0.1 to 0.5mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head whose head height can be easily adjusted.

[0002]

2. Description of the Related Art The positioning accuracy of a magnetic head used in a magnetic recording / reproducing apparatus is an important accuracy for determining the format of information recorded on a medium.

For example, in a video tape recorder widely used for home use, the rotary cylinder has a 180 ° angle.
A pair of magnetic heads attached so as to face each other sequentially record and reproduce image and audio information while obliquely scanning the magnetic tape. The track pitch actually recorded on the magnetic tape is about 60 μm in the 2-hour mode, 6
It is very narrow, about 20 μm in the time mode.

If the above-mentioned pair of magnetic heads cannot accurately scan these tracks, the recorded information cannot be reproduced accurately, and the quality of the reproduced image is significantly deteriorated. In order to prevent this, the scanning pitch of the magnetic head must be accurately adjusted to the track pitch described above, but the height of the magnetic head is an important factor that determines this scanning pitch.

The height of the magnetic head is the distance between the tape guide edge 13 at a predetermined position of the lower cylinder 2 shown in FIG. 5 and the gap end of the head fixed to the upper cylinder 1.

A conventional head height adjusting method will be described below with reference to FIG. First, a spacer (not shown) having a predetermined thickness is sandwiched between the upper cylinder 1 and the head base 4 to which the head chip 3 is attached, and a rough adjustment is performed. Then, the head height is measured using the objective lens 9. , Calculates the adjustment amount required to adjust to a predetermined height.

Next, the insect screw 14 that is in contact with a part of the head base 4 is moved by the necessary adjustment amount.
The head height is adjusted by partially deforming. Repeat this process if necessary.

[0008]

The basis of the conventional adjustment using the insect screw is that the deformation of the head base due to the pushing force of the insect screw within the limit of the elastic deformation of the head base is utilized. In such a case, if the pushing amount of the insect screw changes due to mechanical vibration or temperature change, the deformation amount of the head base changes correspondingly, and the head height may change eventually.

In an actual VTR, there are various factors that generate vibration, such as cylinder rotation and tape transport, and the temperature change due to changes with time of heat generated from these drive systems and changes in operating environment is avoided. I can't.

At present, a screw loosening preventive agent (resin that is fixed at room temperature) is used for insect screws in an attempt to minimize the influence of these factors, but the effect is not sufficient, and it is several microns. The head height had changed in the order of. This change in head height is one of the important factors that affect the image quality of the VTR.

Further, when a fluid bearing is used as the bearing of the rotating cylinder, the relative position of the rotating upper cylinder with respect to the lower cylinder changes due to the rotation of the shaft. Therefore, sufficient accuracy is ensured by the conventional method by adjustment in a stationary state. It was difficult to do so, and in the end, the adjustment work had to be trial and error.

Moreover, the actual work of adjusting the insect screws is performed manually, which is quite complicated.

An object of the present invention is to solve the above problems and to provide a method capable of adjusting the head height of a magnetic head with high accuracy and high efficiency without being affected by vibration or temperature change. ..

[0014]

In order to achieve this object, the present invention provides two or more parallel grooves in the direction perpendicular to the radial direction of the rotary cylinder in the vicinity of the head chip attachment portion of the head base attached to the rotary cylinder. Are formed and laser light is irradiated between the parallel grooves.

[0015]

According to the present invention, the head height can be adjusted even when the upper cylinder is rotated by using the laser processing capable of deforming the head base without contact.
Since the laser irradiation portion is sandwiched by two or more parallel grooves, the adjustment amount per pulse is stable and highly accurate adjustment can be performed quickly.

[0016]

EXAMPLE An example of height adjustment of a magnetic head according to the present invention will be described with reference to FIG.

Thickness with Head Chip 3 Attached 1.
The 5 mm brass head base 4 has a head base 4 and a head base 3 which are arranged in a direction perpendicular to the radial direction of the upper cylinder 1.
A parallel groove 5 of a book is formed. The head base 4 was attached to the upper cylinder 1 with screws 6, and the upper cylinder 1 was fixed to the lower cylinder 2.

In this embodiment, the laser light 7 is Nd:
A short pulse oscillation of a YAG laser (wavelength 1.06 μm) was used. Also, the pulse width of the excitation flash light is 1 ms.
The laser energy obtained when ec and the excitation voltage were 450 volt was about 1 joule per pulse. The converged diameter of the YAG laser was 200 μm.

The upper cylinder 1 in this embodiment is provided with a through hole 8 for passing the laser beam 7. The through hole 8 has an arc shape extending in the rotational direction and has a length of 7 mm. To pass the laser beam 6 while actually rotating it,
The laser oscillation was synchronized with the rotation of the upper cylinder 1.

When the head height is adjusted by laser light, the brass, which is the material of the head base, undergoes expansion, melting, solidification, plastic deformation, and contraction processes due to the energy of the laser light, so that it is easily affected by the peripheral shape of the laser irradiation position. .. Usually, as shown in FIG. 2, the head base 4 is provided with a winding through hole 11 for passing the winding 10 of the head chip 3, and as shown in FIG. 3, the head base 4 is displaced in the direction opposite to the laser irradiation side. Since the concave groove 12 for irradiating the laser beam 7 is provided when the laser beam is irradiated, when the laser beam is irradiated in the width direction of the head base, the displacement amount varies depending on the irradiation position
In order to achieve a predetermined head height, it is necessary to change the laser irradiation energy or the laser light focus.

In this embodiment, since the parallel grooves 5 are formed in the head base 4 in the direction perpendicular to the radial direction of the upper cylinder 1 and the laser light 7 is irradiated between the parallel grooves 5, the parallel grooves 5 are surrounded by the parallel grooves 5. The head base 4 is plastically deformed only in the open region, and the amount of deformation per pulse is stable.

In this embodiment, the distance between the parallel grooves is 0.5 mm,
The groove width is 0.1 mm and the groove depth is 0.2 mm. A stable displacement amount can be obtained by irradiating the space between the parallel grooves with a laser. The interval between the parallel grooves needs to be changed according to the laser irradiation conditions such as the laser irradiation energy and the irradiation spot diameter, but once determined, the interval between the parallel grooves can be set accordingly. The depth of the groove depends on the depth of the plastic deformation region that varies depending on the irradiation spot diameter and energy of the laser light, but since the head base is deformed by the laser light, a plastic deformation region of about 0.1 mm occurs. A groove depth of at least 0.1 mm is necessary, and a maximum of 0.5 mm is sufficient. That is, when the plastic deformation region is formed to be 0.5 mm or more, the head base material is scattered by the irradiation energy of the laser beam, and the original purpose of deforming the head base cannot be achieved. Further, since the groove width is only for preventing the plastic deformation region, basically a fine groove may be used.

When the head height was measured by using the objective lens 9 while actually rotating the upper cylinder at a regular rotation speed, it was -6.5 μm with respect to the predetermined head height dimension. When the laser light was irradiated once between the parallel grooves using the head base shown in FIG. 4, it was deformed to the laser irradiation side of 1.5 μm. Next, when laser irradiation is performed immediately next to the first irradiation position, the deformation is 1.7 μm, and when the laser irradiation position is shifted and the third and fourth irradiations are performed, the displacement amounts are 1.3 μm and 1.9 μm, respectively. A total of 6.6 μm was displaced by four laser irradiations.

The maximum difference between the four displacements was 0.6 μm, and the variation was very small. That is, 1
Since the variation of the deformation amount per pulse is very small,
If the number of pulses is determined when the head height is first measured, it suffices to input a voltage according to the amount of displacement per pulse, and the head height can be adjusted efficiently.

Further, in the embodiment, the laser light is irradiated only between the parallel grooves, but the head height is displaced while irradiating not only between the parallel grooves but also at other portions, and the parallel grooves are used for fine adjustment. A laser beam may be irradiated during the period.

By the way, in the present embodiment, since the magnetic recording / reproducing apparatus using the fluid bearing is used, the head height is adjusted while rotating the rotary cylinder, but the magnetic recording / reproducing does not change in the stationary state. If it is a device, the height may be adjusted in a stationary state. Further, in the present embodiment, welding deformation by irradiation of laser light using light energy was used, but in principle, any method can be used as long as local heating can be performed.

Examples include arc welding using electric energy, electron beam welding, ultrasonic welding using ultrasonic energy, and gas welding using chemical energy.

The above-described head height adjustment according to the present invention does not use insect screws and is due to the plastic deformation of the head base. I do not receive it. Actually, -40
A heat shock test was conducted by repeating the test at 80 ° C and 80 ° C. The deformation of the head base before and after the test was 0.1
It did not change with an accuracy of μm or less.

It is also possible to automate the laser irradiation, the driving system of the condenser lens and the measuring system by computer control. By automating this series of adjustment operations, it is possible to incorporate it into an actual VTR mass production line, and it is possible to perform head adjustment with higher accuracy and reliability more quickly than ever before. It's clear.

[0030]

As described above, according to the present invention, since two or more grooves are provided in the vicinity of the head chip of the head base in the direction perpendicular to the cylinder radial direction, the amount of displacement per pulse of laser light is increased. Therefore, there is an advantage that highly accurate head height adjustment can be performed very easily. In addition, it becomes possible to incorporate it into a VTR mass production line by automation, and the productivity is dramatically improved.
Further, according to the present invention, since the head height is not affected by mechanical vibration or temperature change, the high image quality V due to the narrow track is achieved.
Make it easy to realize TR.

[Brief description of drawings]

FIG. 1 is a diagram showing a main cross section of upper and lower cylinders and a head height adjusting mechanism by laser light according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a conventional head base.

FIG. 3 is a perspective view showing a head base used when the head base is displaced opposite to the laser light irradiation side.

FIG. 4 is a perspective view showing a head base according to an embodiment of the present invention.

FIG. 5 is an enlarged view for explaining the definition of head height.

FIG. 6 is a sectional view of an essential part for explaining a conventional head height adjusting method.

[Explanation of symbols]

 1 Upper Cylinder 2 Lower Cylinder 3 Head Chip 4 Head Base 5 Groove 6 Fixing Screw 7 Laser Light 8 Through Hole 9 Objective Lens 10 Winding 11 Winding Through Hole 12 Recessed Groove 13 Tape Guide Edge 14 Bug Screw

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiaki Maekawa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. Two or more parallel grooves are formed in the vicinity of a head chip attachment portion of a head base attached to a rotary cylinder in a direction perpendicular to the radial direction of the rotary cylinder, and a laser beam is provided between the parallel grooves. A magnetic head characterized in that the head height is adjusted by being irradiated and plastically deforming the head base. 2. The depth of the parallel groove is 0.1 mm or more and 0.5 m.
The magnetic head according to claim 1, which is not more than m.