JPH0378111A - Magnetic head driving device - Google Patents

Abstract

PURPOSE:To obtain a recording track with superior linearity by fixing a cylindrical bobbin supported elastically at a constant position by using a fixing device. CONSTITUTION:Permanent magnets 22, 25, yokes 21, 24 which form a magnetic gap between the permanent magnets, and a magnetic head 16 are mounted on the device. When a current is made flow on shape memory alloy 36 and self-heating occurs in recording, the shape memory alloy 36 is extended in a direction perpendicular to the central axis of the bobbin, and an elastic member 35 is pressed in all directions, which fixes the bobbin 30 at the constant position. Therefore, the magnetic head can be fixed at the constant position without being oscillated in the up-and-down direction even when disturbance, etc., is applied. Thereby, the recording track with superior linearity can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic head drive device, and particularly relates to an improvement of a magnetic head drive device in a magnetic recording/reproducing device such as a video tape recorder or a high-definition video tape recorder. .

[Conventional technology]

FIG. 5 is a cross-sectional view showing the main parts of a rotating drum device including a conventional magnetic head, FIG. 6 is a view taken along arrows ■-■ in FIG.
The drawings are a view taken along the line Vl-VI in FIG. 5, FIG. 8 is a sectional view of FIG. 6, and FIG. 9 is a side view of FIG. 7.

In Figures 5 and 6, 1 is a lower drum, 2 is a bearing attached to this lower drum, 3 is a rotating shaft that is supported by this bearing and rotates, and 4 is fitted to one end of this rotating shaft. pedestal, 5 is an upper drum attached to this pedestal using screws 6, 7 is a magnetic head drive unit attached to this upper drum using screws 8, 9 is a lower transformer attached to lower drum 1, 10 11 is a wiring board attached to the upper drum 5; 12 is a non-rotating contact for supplying control current to the magnetic head drive section 7; 13 is in sliding contact with this contact. 14 is a rotating electrode provided on a part of the pedestal 4, 14 is a connection part that electrically connects the electrode 13 to the magnetic head drive unit 7 via the connection part 15 and the wiring board 11, and 16 is a connection part to the magnetic head drive part 7. Attached magnetic head, connecting portion 17. Wiring board 11. It is electrically connected to the upper transformer 10 via the connecting portion 15 . A recess 18 is provided in a part of the upper drum 5 to accommodate the magnetic head drive section 7, and is formed to be slightly larger than the magnetic head drive section 7 so that the position of the magnetic head 16 can be adjusted. 19 is a position adjustment hole for adjusting the position of the magnetic head 16, and 20 is a magnetic tape that comes into sliding contact with the magnetic head 16.

FIGS. 7, 8, and 9 are diagrams showing the magnetic head drive section 7 in more detail.

In the figure, 21 is a first yoke made of a magnetic material, 22 is a columnar first permanent magnet fixed to this first yoke, and 23 is a first yoke made of a magnetic material.
24 is a second yoke made of a magnetic material and has a convex portion 23a on a part of its inner circumference and is attached to the first yoke 21; 24 is a third yoke made of a magnetic material that is attached to this second yoke; 25 is a third yoke made of a magnetic material; 2. A columnar second permanent magnet fixed to the yoke 24 with the same magnetic poles as the first permanent magnet 22 facing each other;
Reference numeral 6 indicates a pole piece made of a magnetic material and fixed to either one of the second permanent magnets 25 and the first permanent magnet 22; 27 is a leaf spring made of a thin non-magnetic material; and the second yoke 23, and its extending portion 27a is held by the first yoke 21 and the second yoke 23.
The magnetic head 16 is attached to the tip of the magnetic head 16, which protrudes outward through windows 21a and 23a provided therein.

Reference numeral 28 denotes a temporary spring made of a thin plate of non-magnetic material, which is held between the second yoke and the third yoke. 29 is a leaf spring 27.28
The fixing members 30 each held in the
Permanent magnet 22. Second permanent borate 25 and pole piece 26
Fixing member 29 at a position where there is a gap between the outer periphery of
A bobbin 31 is fixed to the bobbin with adhesive 32, and 31 is a coil made of an electric wire having a covering material wound around the bobbin, and a gap is formed around the entire circumference between it and the convex portion 23a of the second yoke 23. have.

Next, the operation will be explained.

To explain with reference to FIG. 8, first, the first permanent magnet 22 is connected to the pole piece 26. 29th yoke 23 and first yoke 21
A magnetic flux is generated by the closed magnetic path created by the Similarly, the second permanent magnet 25 is connected to the pole piece 26. A closed magnetic path formed by the second yoke 23 and the third yoke 24 generates a magnetic flux E in the opposite direction to the magnetic flux.

In this way, both the magnetic flux and the magnetic flux E cross the annular gaps F, G in the same direction, and the total magnetic flux of the first permanent magnet 22 and the second permanent magnet 25 crosses the coil 31.

In this state, the coil 31 is connected to the contact 12 to the electrode 13. When a current is passed through the connecting portions 15 and 14, the coil 31, bobbin 3o, and magnetic head 16 move vertically and linearly in unison, displacing in the width direction of the magnetic tape 20, and tracing the magnetic recording trace with precision. It is supposed to be done.

Further, the magnetic head 16 can be stopped at a fixed position by passing a fixed current through a coil wound around a bobbin.

By the way, Fig. 10 shows the vertical movement of the magnetic head caused by the force exerted on the magnetic head by the tape as a result of the fluctuation of the back electromotive current, and Fig. 11 shows the recorded track due only to the influence of the vibration of the magnetic head that occurs during recording. It can be seen that the influence of vibration affects the track by 2 to 3 μm.

[Problem to be solved by the invention]

Conventional magnetic head drive devices are configured as described above, and in order to perform recording and reproduction using the same head, the magnetic head must be fixed at a fixed position during recording, and conventional magnetic heads using only electrical means cannot be used. When the position is fixed, the magnetic head vibrates vertically together with the bobbin due to the reaction force when the magnetic head enters the magnetic tape and disturbances to the device itself, resulting in poor linearity of the recording track, resulting in problems such as deterioration of image quality.

This invention was made to solve the above-mentioned problems, and allows the magnetic head to be fixed at a constant position without vertical vibration due to disturbances, etc., and to create a recording track with excellent linearity during recording. The object of the present invention is to obtain a magnetic head drive device that can be obtained.

[Means to solve the problem]

A magnetic head drive device according to the present invention includes a permanent magnet, a yoke that forms a magnetic gap between the permanent magnet, and a gimbal type spring, to which the magnetic head is attached, and two upper and lower gimbal springs that extend in the magnetic gap in the axial direction. A cylindrical bobbin that is elastically supported in a movable manner by a cylindrical bobbin and a drive coil wound around the bobbin are provided, and during recording, the bobbin is held constant using a fixing device made of a shape memory alloy or the like. It is to be fixed in place.

[Effect]

The magnetic head drive device according to the present invention includes a permanent magnet,
a yoke forming a magnetic gap with the permanent magnet;
A magnetic head consisting of a cylindrical bobbin to which the magnetic head is attached and elastically supported so as to be movable in the axial direction within the magnetic gap by two upper and lower gimbal springs, and a drive coil wound around the bobbin. In the drive device, during recording, the bobbin is fixed in a fixed place using a fixing device made of a shape memory alloy, etc., so that even when external disturbances are applied, the magnetic head does not vibrate up and down. , can be fixed at a fixed position, and as a result, a recording track with excellent linearity can be obtained.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a magnetic head drive device according to an embodiment of the present invention, FIG. 2 is a diagram showing a fixing device for fixing a bobbin according to an embodiment of the present invention and the current path used therein, and FIG. 3 4 is a diagram showing a device for fixing a bobbin according to another embodiment of the present invention, and FIG. 4 is a diagram showing the operating principle of the bimorph used in FIG. 3.

In the figure, the same parts as in the conventional example are indicated by the same symbols, and 33 is a fixing device for fixing the bobbin 30. In order to fix the bobbin 30 without tilting it, the shape is axially symmetrical with respect to the central axis of the cylindrical bobbin 30. and are arranged axially symmetrically. Further, in this embodiment, the fixing device 33 is attached below the leaf spring 27, but the fixing device 33 may be placed at the center of gravity of the bobbin. In FIG. 2(a), 34 is a fixing member fixed to the first yoke 21 with adhesive; 35
36 is an elastic member with a large coefficient of friction, and 36 is a shape memory alloy, which expands and contracts in a direction perpendicular to the central axis of the bobbin by passing an electric current through it.

FIG. 2(b) shows the path through which the current flows.

Next, the operation will be explained.

During recording, when a current is applied to the shape memory alloy 36 to cause it to self-heat, the shape memory alloy 36 stretches in the H direction shown in FIG. Press the bobbin 30 from all sides.
to be fixed in a certain place.

As described above, in this embodiment, the fixing member 34 is fixed to the first yoke 21 with an adhesive, the shape memory alloy 36, and the elastic member 35 having a large coefficient of friction supported by the shape memory alloy 36. The shape memory alloy 3
6 extends in a direction perpendicular to the central axis of the bobbin 30, and by pressing the elastic member 35 from all sides, the bobbin 30
can be fixed at a fixed location, and as a result, a recording track with excellent linearity can be obtained.

In addition, although shape memory alloy was used for the fixing device in the above example, the structure and configuration of the fixing device is not limited to this.
As shown in FIG. 3, a bimorph may be used.

Specifically, bimorph 38 is generally configured as shown in FIG. 4, with 39a. 39b is a piezoelectric ceramic, 40 is a shim, the piezoelectric ceramics 39a and 39b are magnetized in the same direction, and when a voltage is applied, the piezoelectric ceramic 3
9a moves in the extending direction, and the piezoelectric ceramic 39b moves in the contracting direction, and the whole bends in the J direction. In this way, as shown in FIG. 3, a voltage is applied to the bimorph 38, which is not normally in contact with the bobbin 30, and the bimorph 38 is moved in the direction of ■, and by pressing the bobbin 30 with the bimorph member, the bobbin 38 is held in a fixed place. 30 can be fixed.

Further, in the above two embodiments, the fixing device was constructed using a shape memory alloy or bimorph as shown in FIGS. 2 and 3, but the shape and arrangement of the fixing device are not limited to this.
The shape or arrangement may be axially symmetrical with respect to the central axis of the bobbin, and the position of attachment to the bobbin 30 is not limited to the position below the leaf spring 27, for example, it may be attached to the center of gravity of the bobbin 30.

〔Effect of the invention〕

As described above, the magnetic head fixing device according to the present invention is composed of a fixing member that fixes the bobbin at a certain location, a shape memory alloy, and an elastic member with a large coefficient of friction supported by the shape memory alloy. The magnetic head can be fixed without being affected by device vibration, and as a result, a recording track with excellent linearity can be obtained during recording.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional side view showing a magnetic head driving device according to an embodiment of the present invention, FIG. 2 is a plan view of a bobbin fixing device using a shape memory alloy according to an embodiment of the present invention, and FIG.
The figure is a plan view of a bobbin fixing device according to another embodiment of the present invention using a bimorph, FIG. 4 is a diagram showing the operating principle of the bimorph, and FIG. 5 is a diagram showing the main parts of a rotating drum device including a magnetic head. The cross-sectional view shown in FIG. 6 is a view taken along the line V-■ in FIG.
FIG. 11 is a diagram showing the state of the linearity of a recording track due only to the influence of the vibration of a magnetic head that occurs during recording in the prior art. In the figure, 7 is a magnetic head drive device, 2123, 24
is a yoke, 22.25 is a permanent magnet, 30 is a bobbin, 31
is a coil, 33 is a fixing device, 36 is a shape recording alloy, 38
is a bimorph. Note that the same reference numerals in the figures indicate the same or equivalent parts. Figure 1 culture 311! ! 1 j SoD 1: 7-1”M 2.〃Even 3 B# 21:'%17-ri 3o: Boy 31:7 da/mu 32: lZI to DE, ゑsyf Figure 7 Figure 10 Procedures (Public Paperback Seal) September 1, 1990, Indication of the Case Patent Application No. 1-215215 J Day 2゜ Title of the Invention Magnetic Head Drive Device 3゜Relationship with the Case of Person Who Makes Corrections Patent Application Address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Corporation 5, Claims column 1 of the specification to be amended, Detailed description of the invention column,
and drawings (Figure 4) 6. Contents of amendment (1) The scope of claims in the specification will be corrected as shown in the attached sheet. (2) Correct "transferable" in line 17 of paragraph 7 of the specification to "displaceable." (3) Figure 4 is corrected as shown in the attached sheet. Address: 1-23-43 Esaka-cho, Suita-shi, Osaka Prefecture Claims: (1) A permanent magnet, a yoke forming a magnetic gap between the permanent magnet, and a magnetic head attached to the magnetic gap. A magnetic head drive device for a magnetic recording/reproducing device includes a cylindrical bobbin that is elastically supported to be displaceable in the axial direction by two upper and lower gimbal springs, and a drive coil wound around the bobbin. A magnetic head drive device comprising a fixing device for fixing the bobbin. Diagram

Claims (1)

[Claims] (1) A permanent magnet, a yoke that forms a magnetic gap between the permanent magnet, and a magnetic head are attached and elastically supported so as to be movable in the axial direction within the magnetic gap by two upper and lower gimbal springs. A magnetic head drive device for a magnetic recording/reproducing device comprising a cylindrical bobbin and a drive coil wound around the bobbin, characterized in that the magnetic head drive device comprises a fixing device for fixing the bobbin during recording. Device.