JP2563727B2 - Magnetic head height adjustment method - Google Patents

Description

Detailed Description of the Invention

[0001]

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

[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, two pairs of magnetic heads mounted at 180 ° opposite to a rotating cylinder sequentially scan an image while obliquely scanning a magnetic tape. And audio information is recorded and played back. The track pitch actually recorded on the magnetic tape is very narrow, about 60 μm in the 2-hour mode and about 20 μm in the 6-hour mode.

If the above-mentioned two pairs of magnetic heads cannot scan these tracks accurately, the recorded information cannot be reproduced accurately and the quality of the reproduced image will be significantly deteriorated. In order to prevent this, it is necessary to accurately match the scanning pitch of the magnetic head with the above-mentioned track pitch, 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 (H in FIG. 4) between the reference surface 25 of the lower cylinder 22 shown in FIG. 4 and the gap end of the head fixed to the upper cylinder 21.

First, in FIG. 3, a spacer (not shown) having a predetermined thickness is sandwiched between the upper cylinder 21 and the head base 24 to which the head chip 23 is attached, and after roughly adjusting, an objective lens 26 is used. While observing the head height, the insect screw 27 hitting a part of the head base 24 is screwed in the direction of the arrow 28 by a necessary adjustment amount, and the head base 24 is partially deformed to thereby obtain a predetermined head height. Adjust so that

Also, the plate material is welded and deformed (Welding Engineering, Science and Engineering Co., Ltd., issued in 1979, or JP-A-62-93028).
There is a method of giving distortion by bending a plate material with a laser), and a method of irradiating a magnetic head with light heat such as a laser using this method (Japanese Patent Laid-Open No. 2-328).
703, "Magnetic Head Positioning Method").

[0008]

However, the conventional adjustment using the insect screw uses the deformation of the head base due to the pushing force of the insect screw within the limit of the elastic deformation of the magnetic head base. is there. 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 eventually change.

In an actual VTR, there are various factors that generate vibrations such as cylinder rotation and tape transport, and
Inevitably, temperature changes due to changes over time in the heat generated from these drive systems and changes in the operating environment.

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 from 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 influence the image quality of the VTR. Moreover, the actual adjustment work using the insect screw is performed by humans, which is quite complicated.

To adjust the azimuth of the magnetic head, a prescribed azimuth angle is produced at the time of manufacturing the magnetic head gap and the azimuth is set on the magnetic head, and the cutting accuracy of the magnetic head chip is set to an angle of several minutes. Is also very difficult. If the magnetic head base on which the head chip is installed is deformed by mechanical vibration or temperature change, the mounting azimuth angle also changes and the initial accuracy cannot be maintained.

If reproduction is performed in another VTR while the azimuth of the magnetic head in one VTR is deviated, there is a problem that the output is lowered because the azimuth angle is different.

Further, although there is an azimuth angle adjustment of a magnetic head by an insect screw like a VTR of M2 which is mainly used for broadcasting, there are various factors such as rotation of a cylinder and tape feeding, which cause vibration. Further, azimuth angle deviation due to temperature change due to changes with time of heat generated from these drive systems and changes in use environment is unavoidable.

Further, by irradiating the head base with a laser,
When adjusting the height, there is a drawback that the number of magnetic heads that can be arranged in the cylinder is limited if the cylinder diameter is small.

In view of the above points, the present invention makes it possible to easily adjust the height of the magnetic head arranged in the rotary cylinder without being affected by mechanical vibration or temperature change in the magnetic recording / reproducing apparatus, and further to reduce the cylinder diameter. Even so, it is an object of the present invention to provide a magnetic head height adjusting method capable of adjusting the height without being affected by the number of head chips.

[0016]

In order to achieve this object, the present invention deforms the magnetic head by irradiating a laser beam to an irradiation portion processed for laser irradiation in a portion of a rotating cylinder supporting the magnetic head. The height of the magnetic head is adjusted by deforming the irradiation unit without performing the above.

Further, when the thickness of the laser irradiation area of the irradiation portion is uniform, the displacement of the magnetic head in the height direction is obtained, and when the thickness of the laser irradiation area is non-uniform, the magnetic head is displaced. The height of the magnetic head is adjusted by irradiating the irradiation section with a laser beam so that the displacement of the gap in the azimuth direction can be obtained.

[0018]

According to the present invention, by using the laser processing described above, the head height can be adjusted even when the rotary cylinder is rotated, and the laser beam is applied to the irradiation part supporting the magnetic head. Since the height direction of the magnetic head is adjusted by deforming the portion, the height of the magnetic head can be adjusted with high accuracy.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A height adjusting method for a magnetic head according to an embodiment of the present invention will be described below with reference to the drawings. 1 and 2 show a magnetic head height adjusting method and a state of the magnetic head at the time of height adjustment in an embodiment of the present invention. For example, it is assumed that the head height is adjusted by a laser beam that does not use an insect screw shown in FIG.

In the conventional height adjustment of the head, the magnetic head is installed in the head base and the height is adjusted by applying an external force to the head base.
The rotary cylinder 2 having a structure that can be directly installed on the rotary cylinder 2 without attaching the. That is, the irradiation section 4 for irradiating the laser beam 3 is formed on one side of the rotary cylinder 2, and the magnetic head 1 is fixed to the irradiation section 4 without the intervention of the head base. Spaces are formed above and below the irradiation unit 4, and the irradiation unit 4 can be deformed by the irradiation of the laser beam 3.

Further, a hole 5 for the irradiation laser is provided as a passage of the laser beam 3 in the rotary cylinder 2 so that the irradiation unit 4 can be irradiated with the laser beam 3. This is so large that the laser beam 3 does not hit the rotating cylinder 2. By irradiating the rotating cylinder 2 with the laser beam 3 to distort the irradiation position of the irradiation unit 4, the displacement of the head height in the laser irradiation side, that is, in this case, in the upward direction can be obtained.

In this embodiment, the laser beam is Nd:
Short pulse oscillation of a YAG laser (wavelength 1.06 μm) was used. Also, the pulse width of the flash light for excitation is 1 ms.
The laser energy obtained when ec and the excitation voltage were 450 volt was about 1 Joule per pulse.

The size of the above laser beam is set to 200 in the vertical direction.
When the irradiation unit 4 of the rotary cylinder 2 is irradiated with 1 pulse of energy of μm and horizontal width of 4000 μm, a deformation amount of 1 μm is obtained in the head height direction and the deformation is performed in parallel with the head height direction. Further, this adjustment amount can be adjusted in units of 0.1 micron by changing the intensity of the laser. However, the case of being deformed in parallel is the case where the thickness portion of the irradiation portion 4 is uniform.

Further, by adjusting the height of the magnetic head, the shape of the laser beam is flattened while the cylinder is rotating, and the irradiation unit 4 is used.
By irradiating the magnetic head, it is easy to move the magnetic head in parallel in the height direction.

As shown in FIG. 2, in the case of the irradiation portion 41 in which the thickness of the mounting portion of the rotary cylinder 2 of the magnetic head 1 is uneven, when the laser is irradiated, the displacement of the magnetic head 1 in the azimuth direction, that is, Since the displacement of the head gap 6 in the rotation direction is obtained, the adjustment in the azimuth direction is also possible. Here, the displacement in the rotational direction is such that the thinner the thickness at the irradiation position of the irradiation unit 41 is, the larger the strain amount is, so that the thinner in the thickness direction is displaced upward in the head height direction. Receive distortion.

As described above, when the height of the compact magnetic head is adjusted to directly irradiate the irradiation portion of the rotary cylinder 2, the irradiation area is limited to the size of the bed base to which the magnetic head 1 is attached. In some cases,
By installing the magnetic head 1 directly on the rotary cylinder 2, there is an advantage that the irradiation area can be made larger than that of the head base. In addition, even if the cylinder diameter is reduced in response to the downsizing of equipment, the head base is not required, so it is less affected by the mounting area of the magnetic head, and a large number of magnetic heads can be arranged. No need for a base, so you only have to adjust the height once. Furthermore, there is an advantage that the height error can be small.

Further, it can be incorporated into a VTR mass production line by automation, and the productivity thereof is dramatically improved. Furthermore, according to the present embodiment, the head height is not affected by mechanical vibration or temperature change, so that it is easy to realize a high image quality VTR by narrowing the track.

In this embodiment, welding deformation by irradiation with laser light using light energy was used, but in principle, any method can be used as long as local heating can be performed. For example, arc welding and electron beam welding using electric energy, ultrasonic welding using ultrasonic energy, gas welding using chemical energy, and the like can be given.

As described above, according to the present invention, the magnetic head
Even if it is not deformed, the height of the magnetic head placed on the rotating cylinder can be easily adjusted with high accuracy without being affected by mechanical vibration or temperature change in the magnetic recording / reproducing device, and the cylinder diameter is small. However, the height can be adjusted without being affected by the number of magnetic heads.

Further, by adjusting the height of the magnetic head and flattening the shape of the laser beam in a cylinder rotating state and irradiating the laser beam on the magnetic head, there is an advantage that the magnetic head can be moved in parallel in the height direction. In addition, it can be incorporated into a VTR mass production line by automation, and the productivity is dramatically improved. Further, according to the present invention, the head height is not affected by mechanical vibration or temperature change, which facilitates realization of a high image quality VTR by narrowing the track.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an irradiation state of a magnetic head according to an embodiment of the present invention.

FIG. 2 is a front view of an irradiation portion of a magnetic head for explaining the present embodiment.

FIG. 3 (a) is a main cross-sectional view of the upper and lower cylinders showing a conventional height adjustment with an insect screw.

FIG. 4 is a diagram for explaining the definition of head height.

[Explanation of symbols]

 1 Magnetic Head 2 Rotating Cylinder 3 Laser Beam 4 Irradiator 5 Laser Irradiation Hole 6 Head Gap

Front page continuation (72) Inventor Toinchi Ken, Kadoma City, Osaka Prefecture 1006 Kadoma, Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-3-248314 (JP, A) JP-A-2-206015 (JP, A) JP 58-199431 (JP, A) JP 1-102715 (JP, A)

Claims (2)

(57) [Claims] 1. A magnetic head that irradiates a laser beam onto an irradiation portion processed for laser irradiation in a portion of a rotating cylinder that supports a magnetic head, and deforms the irradiation portion without deforming the magnetic head. A magnetic head height adjusting method characterized in that the height of the magnetic head is adjusted. 2. The displacement in the height direction of the magnetic head is obtained when the thickness in the laser irradiation region of the irradiation portion is uniform, and the magnetic head gap is obtained when the thickness in the laser irradiation region is uneven. 2. The height adjusting method for a magnetic head according to claim 1, wherein the height of the magnetic head is adjusted by irradiating the irradiation section with a laser beam so that the displacement in the azimuth direction can be obtained.