JPH04310614A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To provide a magnetic recording and reproducing device capable of an adjusting method in which due to the temperature and the mechanical vibration of a head height fitted at a rotating cylinder does not change, in the magnetic recording and reproducing device with the rotating cylinder. CONSTITUTION:At an upper cylinder 1 near a head base 4 fitted at an upper cylinder 1, a through hole 8 is provided, a laser beam 6 is irradiated near the part to stick a head chip 3 through the through hole 8 and the head base 4 is deformed only for the prescribed quantity by the welding deformation.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording/reproducing apparatus for adjusting the height of a magnetic head.

0002

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

[0003] For example, in a video tape recorder that is widely used for home use, the rotating cylinder has a 180°
A pair of magnetic heads mounted facing each other record and reproduce image and audio information while sequentially scanning the magnetic tape diagonally. The track pitch actually recorded on a magnetic tape is very narrow, 60 μm in the 2-hour mode and 20 μm in the 6-hour mode.

[0004] If the above-mentioned pair of magnetic heads cannot accurately scan these tracks, recorded information cannot be accurately reproduced, and the quality of the reproduced image deteriorates significantly. To prevent this, it is necessary to precisely match the scanning pitch of the magnetic head to the above-mentioned track pitch, and an important factor that determines this scanning pitch is the height of the magnetic head.

The height of the magnetic head is the distance between the tape guide edge 11 at a predetermined position of the lower cylinder 2 shown in FIG. 3 and the end of the gap of the head fixed to the upper cylinder 1.

A conventional head height adjustment method will be described below with reference to FIG. First, after making a rough adjustment by inserting a spacer (not shown) of a predetermined thickness between the upper cylinder 1 and the head base 4 to which the head chip 3 is attached, the head height is measured using the objective lens 7. , calculate the amount of adjustment required to adjust to a predetermined height.

Next, the head height is adjusted by partially deforming the head base by the necessary amount of adjustment using the insect screw 10 that is in contact with a part of the head base 4. Repeat this task if necessary.

[0008]

The basic principle of adjustment using a conventional insect screw is to utilize 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. In such a case, if the amount of push-in of the insect screw changes due to mechanical vibration or temperature change, the amount of deformation of the head base will change by that amount, and there is a possibility that the head height will eventually change.

In actual VTRs, there are various factors that generate vibration, such as cylinder rotation and tape transport, and temperature changes due to changes in the heat generated from these drive systems over time and changes in the usage environment must be avoided. I can't do it.

[0010]Currently, in an attempt to minimize the effects of these factors, screw loosening agents (resin that sticks at room temperature) are used for insect screws, but the effect is not sufficient; The head height had changed depending on the order. This change in head height is one of the important factors that affects the image quality of a VTR.

[0011] Furthermore, when a hydrodynamic bearing is used for the bearing of the rotating cylinder, the relative position of the rotating upper cylinder to the lower cylinder changes as the shaft rotates, so the conventional method of adjustment in a stationary state can ensure sufficient accuracy. It was difficult to do so, and in the end, adjustment work had to be a trial and error process.

[0012] Moreover, the actual adjustment work using the insect screws was done manually and was quite complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method that can solve the above problems and adjust the head height of a magnetic head with high precision and high efficiency without being affected by vibrations or temperature changes. .

[0014]

[Means for Solving the Problem] In order to achieve this object, the present invention provides a through hole so that a laser beam can be irradiated to the rotating cylinder near the head chip attachment portion of the head base attached to the rotating cylinder. It is something.

[0015]

[Operation] The present invention uses laser processing that can deform the head base without contact, and the head height can be adjusted even when the upper cylinder is rotated, so highly accurate adjustments can be made quickly. It has an effect.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of height adjustment of a magnetic head according to the present invention will be described with reference to FIG. A head base 4 made of brass with a thickness of 1.5 mm to which a head chip 3 was attached was attached to the upper cylinder 1, and the upper cylinder 1 was fixed to the lower cylinder 2.

In this embodiment, as the laser beam 6, Nd:
Short pulse oscillation of a YAG laser (wavelength: 1.06 μm) was used. In addition, the pulse width of the excitation flash light was set to 1 ms.
ec, the laser energy obtained when the excitation voltage was 450 volts was about 1 joule per pulse. The focusing diameter of the YAG laser was 200 um.

In this embodiment, the upper cylinder 1 is provided with a through hole 8 through which the laser beam 6 passes. This through hole has a circular arc shape extending in the direction of rotation and has a length of 7 mm. In order to pass the laser beam 6 while actually rotating, the laser oscillation was synchronized with the rotation of the upper cylinder 1.

As shown in FIG. 4, the head height is determined by a dimension H from a predetermined position of the lower cylinder, and it is necessary to match the track height of the head chip bonded to the head base. When the head height was actually measured using the objective lens 7 while rotating the upper cylinder at a regular rotation speed, it was -6.5 um with respect to the above dimensions. Therefore,
When the head base was deformed by irradiating the head base with a laser beam from above the through hole provided in the upper cylinder, the amount of deformation obtained was 6 um, which was only 0% compared to the target.
．． The deviation was 5 um.

Another embodiment will be described with reference to FIG. Depending on the head chip bonded to the head base, the track height of the head can be negative or positive with respect to the dimension H. Since the head base 4 is deformed toward the irradiation side by laser irradiation, if the dimension H is negative, the laser should be irradiated from the upper cylinder side, and if it is positive, the laser should be irradiated from the lower cylinder side. . When the head height was actually measured using the objective lens 7 while rotating the upper cylinder at a regular rotation speed, it was found to be +10 um with respect to the above dimensions. Therefore, when the base was deformed using the laser on the lower cylinder side, the amount of deformation obtained was 9.7 um, a deviation of only 0.3 um from the target.

Another embodiment will be described with reference to FIG. The upper cylinder 1 is provided with a through hole 8 for irradiating a laser from above the head base 4 and a through hole 8 for irradiating the laser from below the head base 4. The lower cylinder 2 is provided with a mirror 9 for changing the direction of the laser 6 irradiated from above by 180 degrees in order to irradiate the laser 6 from below the head base 4 . This mirror may be a prism, that is, it may be anything that changes the direction of laser light irradiation. The pair of mirrors 9 may be located at one location inside the lower cylinder, and the laser beam may be irradiated to that location when the head base rotates. As a means of irradiating from the bottom of the head base, it is only necessary to install a pair of mirrors on the lower cylinder, so it is very inexpensive.
Laser irradiation on both sides becomes possible with a simple method.

By the way, in this embodiment, since a magnetic recording/reproducing device using a fluid bearing was used, the head height was adjusted while rotating the rotary cylinder. If the device is in a stationary state, the height may be adjusted. Further, in this embodiment, welding deformation by laser beam irradiation using optical energy was used, but in principle, any method that can perform local heating may be used. Examples include arc welding and electron beam welding using electrical energy, ultrasonic welding using ultrasonic energy, and gas welding using chemical energy.

The head height adjustment according to the present invention described above does not use insect screws and is based on plastic deformation of the head base, so it is completely free from the effects of mechanical vibration and temperature changes that were problems in the past. I don't accept it. Actually -40℃
A heat shock test was conducted by repeatedly heating the head to 80°C, and the amount of deformation of the head base before and after the test was 0.1μ.
It did not change with an accuracy of less than m.

It is also possible to automate the laser irradiation and the focusing lens drive system and measurement system by computer control. By automating this series of adjustment work, it will be possible to incorporate it into the actual VTR mass production line, and it will be possible to perform head height adjustment more quickly and with higher precision and reliability than ever before. It's obvious.

[0025]

As described in the embodiments above, according to the present invention, a through hole is provided in the rotary cylinder near the fixed head base, so that regardless of whether the cylinder is rotating or stationary, The head height can be adjusted by irradiating the head base with a laser through the through hole. Therefore, there is an advantage that highly accurate head height adjustment can be performed very easily, and by automating it, it becomes possible to incorporate it into a VTR mass production line, and its productivity is dramatically improved. Further, according to the present invention, since the head height is not affected by mechanical vibrations or temperature changes, it is easy to realize a high-quality VTR by narrowing the tracks.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an upper and lower cylinder and a head height adjustment mechanism using a laser beam, explaining an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an upper and lower cylinder and a head height adjustment mechanism using a laser beam, explaining another embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a head height adjustment mechanism using upper and lower cylinders and a laser beam, explaining another embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating the definition of head height.

FIG. 5 is an explanatory diagram illustrating a conventional head height adjustment method.

[Explanation of symbols]

1 Upper cylinder 2 Lower cylinder 3 Head chip 4 Head base 5 Fixing screw 6 Laser light 7 Objective lens 8 Through hole 9 Mirror 10　Insect screw 11 Tape guide edge

Claims (2)

[Claims] 1. A magnetic recording and reproducing device comprising a rotating cylinder and a fixed cylinder in which a magnetic head with a head chip fixed to the tip of a head base is mounted, the head base being attached to the rotating cylinder side. A through hole is provided in the rotary cylinder, and a laser beam is irradiated onto the head base from above the through hole, and the head base is angularly deformed at the portion irradiated with the laser beam, thereby increasing the head height. A magnetic recording/reproducing device characterized in that: is adjusted. 2. The magnetic recording and reproducing apparatus according to claim 1, further comprising a configuration that allows laser light to be irradiated from both sides of the head base.