JPS62275311A - Magnetic head displacing device - Google Patents

Abstract

PURPOSE:To avoid separation between a magnetic head and a recording medium despite the bend of a bimorph piezoelectric element supporting the magnetic head and at the same time to obtain a thin and compact displacement device for the magnetic head, by setting said piezoelectric element so that the bent plane of the piezoelectric element is set parallel with a magnetic recording medium. CONSTITUTION:A pair of bimorph piezoelectric elements 18f and 18f are set to that the polarizing directions of piezoelectric elements 11f and 12f are set opposite to those of piezoelectric elements 11r and 12r and also that an electrode 13f is connected to an electrode 13r via a connection line 32 together with electrodes 16f and 16r connected via a connection line 33 respectively. In such a constitution, both bent electric terminals 22 and 23 bend in the direction opposite to each other when the drive voltage is applied between both terminals 22 and 23. Furthermore, the length is fixed at the same value among those elements 11f, 12f, 11r and 13r so as to secure the same bend value between both elements 18f and 18r. Then both elements 18f and 18r are set so that their bent displacement planes are parallel with the plane of a magnetic disk (magnetic recording medium) 24.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention "Technical Field" The present invention relates to a magnetic head displacement device using a bimorph piezoelectric element.

"Prior art and its problems" A bimorph piezoelectric element is constructed by laminating and bonding a pair of electrically polarized piezoelectric elements (ceramic elements) with a visible metal substrate sandwiched between them. is one electrode terminal, and the terminal connecting the piezoelectric elements on both sides is the other electrode terminal. This bimorph piezoelectric element has one end fixed and the other end free, and the free end can be deflected by applying an appropriate voltage between both terminals. Konoto.

The amount of deflection of the free end of the blade can be controlled by varying the magnitude of the applied voltage, and the direction can be controlled by local conversion.

Therefore, if this bimorph piezoelectric element is used, a tracking control device such as a video tape recorder (VTR) can be constructed, for example.

Figures 4 and 5 show conventional examples.
Reference numeral 1.12 denotes a piezoelectric element made of a piezoelectric ceramic material such as PzT type, and electrodes 13, 14 and electric! 115.16 are applied respectively. Then, the polarization directions of the piezoelectric elements 11 and 12 are aligned in the same direction, a flexible metal substrate 17 is sandwiched between them, and these are laminated and bonded with adhesive to form a bimorph piezoelectric element 18. It's been done.

This bimorph piezoelectric element 18 has one end connected to a support base 19.
A magnetic head 20 is fixed to the other free end. Head gap portion 20 of this magnetic head 2Q
a protrudes from the free end of the bimorph piezoelectric element 1. Bimorph piezoelectric element 18 and magnetic head 20 are substantially perpendicular to magnetic recording medium 24 .

The magnetic head displacement mechanism described above is based on the electrode 13 of the piezoelectric element 11.
When a driving voltage is applied between the curved electrical terminal 22 connecting the electrode 16 of the piezoelectric element 12 and the terminal 23 connected to the visible metal substrate 17, stress is generated within the piezoelectric elements 11 and 12. Since the visible metal substrate 17 is visible, the entire bimorph piezoelectric element 18 is curved, and the magnetic head 20 is displaced with respect to the magnetic recording medium 24. Therefore, by applying a drive voltage corresponding to the tracking deviation to the curved electrical terminals 22 and 23, this deviation can be corrected. Bimorph piezoelectric element 18 shown in chain lines in FIG.
(Magnetic head 20) is shown in an exaggerated manner after being displaced by applying a driving voltage.

However, in this conventional device, when the bimorph piezoelectric element 18 is bent, the magnetic head 2 is bent as shown by the chain line in FIG.
0 is separated from the recording medium 24, and the magnetic head 2
There was a problem that 0 was tilted with respect to the recording medium 24. Both of these include the magnetic head 20 and the recording medium 24.
This disturbs the optimal mushroom closure system and causes deterioration of the recording and reproducing characteristics.

Further, in this conventional device, the magnetic head 20 and the recording medium 24
Since they are in constant contact with each other, there is a problem in that sliding contact shortens the lifespan of both.

``Object of the Invention'' The present invention solves the above problems, and in a magnetic head displacement device using a bimorph piezoelectric element, when a driving voltage is applied, the magnetic head does not separate from the recording medium.
It is an object of the present invention to provide a device that can maintain an optimal position III relationship between the magnetic head and the recording medium even during tracking correction without tilting the magnetic head with respect to the recording medium.

Broadly speaking, it is an object of the present invention to provide a device that can bring a magnetic head and a magnetic recording medium into contact only during recording and reproduction, and can extend the life of the magnetic head and recording medium.

"Summary of the Invention" The present invention provides that one of the reasons why the magnetic head separates from the recording medium is that in conventional devices, the bimorph piezoelectric element and the recording medium are placed at a distance of 1 [1ffi] at right angles to each other. Based on the analysis that there is, first, the curved displacement plane of the bimorph piezoelectric element is made parallel to the magnetic recording medium, and a magnetic head is fixed on the magnetic recording medium side of the bimorph piezoelectric element.

Then, when the bimorph piezoelectric element is bent with this interposition,
The problem of the azimuth angle between the magnetic head and the track of the magnetic recording medium changing can be solved by connecting a pair of bimorph piezoelectric elements that curve in opposite directions using the same drive voltage, and this can improve the roughness. In order to make it possible to bring the magnetic head and the magnetic recording medium into and out of contact with each other, a pair of bimorph piezoelectric elements is supported on a support base so that the magnetic head can be moved into and out of contact with the magnetic recording medium. Magnetic head +M that displaces the magnetic head with respect to the magnetic recording medium to make the magnetic head 7 m away from the magnetic recording medium.
It is characterized by providing a jli1 means.

``Embodiment of the Invention'' The present invention will be explained with reference to the illustrated embodiment. 0M1 and 2 show the first embodiment of the present invention, and the elements are the same as the conventional example shown in FIGS. 4 and 5. are given the same reference numerals.

A pair of bimorph piezoelectric elements 18f and 18r connected and used in the present invention are formed at the front end of a common flexible electrode substrate 3o. Bimorph piezoelectric element 18
f is an element to which the same magnetic head 2o as in the conventional device is to be fixed at its tip, and the bimorph piezoelectric element 18r is an element whose base is pivoted to a support base 19 by a shaft 21.
The structures of both piezoelectric elements themselves are the same as those explained in FIGS. M4 and M5, so FIGS.
The symbols f and rl are used for the elements explained in the figure, respectively.
Fr is also shown.

This pair of bimorph piezoelectric elements 18f, 18r has polarization directions of piezoelectric elements 11f, 12f, and piezoelectric elements 11r, 1
The polarization direction of electrode 2r is reversed, and the electrode 13f and electrode 13r
, and the electrode 16f and the electrode 16r are connected to the connecting wire 3.
2.33, and therefore the curved electrical terminal 2
2.23 When a driving voltage is applied to darkness, it curves in opposite directions.

Further, in order to make the bimorph piezoelectric elements 18f and 18r the same amount of curvature, the lengths of the piezoelectric element 11f (12f) and the piezoelectric element 11r (13r) are set to be the same.

The pair of bimorph piezoelectric elements 18f and +8r connected to each other are connected to a magnetic disk (magnetic recording medium) 24.
The curved displacement plane is parallel to the plane of . Moreover, this bimorph piezoelectric element 18f, 1
8r faces in the tangential direction of the magnetic disk 24, and the magnetic head 20 is fixed to the free end of the front bimorph element 18f so as to face the recording disk 24.

The above is a mechanism for causing the magnetic head 20 to trace the tracks of the recording medium 24, but the present invention is further provided with a magnetic head approaching/separating means for roughly moving the magnetic head 2o toward and away from the recording medium 24.

This magnetic head contact/separation means achieves its purpose by swinging and displacing a pair of bimorph piezoelectric elements 18f and 18r that are swingable around the shaft 21, and a third bimorph piezoelectric element is used as the driving force. 40 is used.

The structure of the bimorph piezoelectric element 40 is the same as the bimorph piezoelectric elements 18f and 18r described above. That is, electrodes 43, 44 and 45, 46 are provided on each main surface (both sides) of a piezoelectric element 41, 42 made of a piezoelectric ceramic material such as PzT.
are adhered to each other, the polarization directions of the piezoelectric elements 41 and 42 are aligned in the same direction, a flexible metal substrate 47 is sandwiched between them, and these are laminated and bonded with adhesive. ing. A driving voltage is applied to the electrodes 44.45 through the substrate 47 and the curved electrode terminal 481Fr, and to the electrodes 43.46 through the same terminal 491Fr.

This bimorph piezoelectric element 40 is a bimorph piezoelectric element 1
Located perpendicularly to the lower surfaces of 8f and 18r,
Its base end is fixed and the support base 1 is fixed with a Subamorph piezoelectric element 4o.
It is fixed at 9. That is, their curved planes are orthogonal to each other, and the free end of the bimorph piezoelectric element 4o is in contact with the lower surface of the bimorph piezoelectric element 18r.

Further, one end of a tension spring 55 is attached to the opposite side of the bimorph piezoelectric element 18f from the magnetic head 20, and the other end of this tension spring 55 is fixed to a fixing portion 56.

When the voltage applied to the bimorph piezoelectric element 40 is removed, this tension spring 55 causes the bimorph piezoelectric elements 18f and 1
8r is rotated about the shaft 21 in a direction away from the recording medium 24, which acts to move the magnetic head 2o away from the recording medium.

In this device having the above configuration, when a drive voltage is applied to the curved electrode terminals 48 and 49 of the bimorph piezoelectric element 40, the bimorph piezoelectric element 40 curves in accordance with the polarity thereof. Therefore, as described above, in the non-energized state shown in FIG. 1, the force of the tension spring 55 causes the magnetic head 20 to separate from the recording medium 24,
When the bimorph piezoelectric element 40 is bent upward by an appropriate amount as shown in the figure, the tip of the bimorph piezoelectric element 40 pushes up the bimorph piezoelectric elements +8f and 18r so that the magnetic head 20 properly contacts the magnetic recording medium 24. For example, the magnetic head 20 can be brought into contact with the recording medium 24 only during recording and reproduction.

Further, while observing the distance (contact state) between the magnetic head 20 and the recording medium 24, it is also possible to control the voltage applied to the bimorph piezoelectric element 40 so as to optimize the distance.

In the state shown in FIG. 2, the curved electrical terminals 22, 23
When a voltage is applied between the bimorph piezoelectric elements 18f and 18
The same voltage is applied to r via connection lines 32,33. For this reason, the pixel elements are curved in different directions, as shown in an exaggerated manner in FIG. Since the pixel elements have the same length, the curvature l (distortion) occurs equally in opposite directions, so the azimuth angle between the magnetic head gap 20a of the magnetic head 20 and the recording track of the magnetic disk 24 does not change. Bimorph piezoelectric elements 18f, 18r
The tracking deviation of the magnetic head 2o can be corrected by controlling the amount of curvature and the direction of curvature of the magnetic head 2o by a voltage applied between the bending electric terminals 22 and 23.

Furthermore, since the curved displacement planes of the bimorph piezoelectric elements 18f and 18'' can be made parallel to the magnetic disk 24 in the state shown in FIG. Furthermore, according to this arrangement, the entire device can be made thinner than conventional devices.

In the above embodiment, a pair of bimorph piezoelectric elements are oscillated to move the magnetic head 20 away from the recording medium 24 by Wi, whereas in the embodiment shown in FIG. The magnetic head 20 is separated from the recording medium 24 by 'Wi'. Therefore, the base of the bimorph piezoelectric element 18r is fixed to a lifting table 51, and a laminated piezoelectric element 52 as a magnetic head contact/separation means is interposed between the lifting table 51 and the support table 19. This laminated piezoelectric element 52 changes the amount of expansion depending on the magnitude of the applied voltage applied between the expandable electric terminals 53 and 54.

Therefore, according to this embodiment, the magnetic head 20 can be moved parallel to the plane of the recording medium 24 to be separated by Wi. Also in this embodiment, a restoring tension spring can be applied to the bimorph piezoelectric elements 18f and 18r.

"Effects of the Invention" As described above, in the present invention, the bimorph piezoelectric element supporting the magnetic head is arranged so that its curved plane is parallel to the magnetic recording medium. It is possible to reduce the thickness and size of the device without separating from the device. Since the pair of bimorph piezoelectric elements are connected in such a way that their curved directions are opposite to each other, the azimuth angle between the magnetic head and the recording track of the recording medium does not change even when curved. It is possible to always maintain a correct positional relationship with the medium and perform more preferable recording and reproduction.

In general, since the magnetic head fixed to the pair of bimorph piezoelectric elements can be brought into contact with and separated from the recording medium by the magnetic head Wi forward means, the magnetic head and the recording medium are brought into sliding contact only during recording and reproduction. It is possible to extend the lifespan of both.

[Brief explanation of drawings]

1 and 2 are perspective views of a magnetic head displacement bag according to a first embodiment of the present invention in different operating states;
FIG. 4 is a perspective view showing a second embodiment of the present invention, FIG. 4 is a perspective view showing an example of a conventional magnetic head displacement device, and FIG. M5 is a front view of the same. 11f, llr, 12f, 12r...piezoelectric element,
13f, 13r, 14f, 14r, 15f
, 15r, 16f, 16r...electrode, 18f,
18r... Bimorph piezoelectric element, 19... Support stand,
20... Magnetic head, 22.23... Curved electric terminal, 30... Flexible metal substrate, 4o... Third bimorph piezoelectric element, 41.42... Piezoelectric element, 43.44
．． 45.46... Electrode, 47-... Flexible electrical board,
48... Curved electrode terminal, 52... Laminated piezoelectric element,
53.54... Telescopic electrical terminal. Patent applicant: Asahi Optical Industry Co., Ltd. 5N6 Figure 2

Claims (3)

[Claims] (1) In a magnetic head displacement device using a bimorph piezoelectric element that changes the amount and direction of curvature by changing the magnitude and polarity of an applied voltage, a pair of bimorph piezoelectric elements are connected so that their curvature directions are opposite to each other. A pair of connected bimorph piezoelectric elements are arranged so that their curved displacement planes are substantially parallel to the magnetic recording medium, and a magnetic head for recording and reproducing information on the magnetic recording medium is fixed to one end thereof. The pair of bimorph piezoelectric elements are supported on a support base so that the magnetic head can move toward and away from the magnetic recording medium, and the pair of bimorph piezoelectric elements are displaced relative to the magnetic recording medium to move the magnetic head toward and away from the magnetic recording medium. 1. A magnetic head displacement device comprising a magnetic head approaching and separating means for moving the magnetic head toward and away from the magnetic head. (2) In claim 1, the ends of the pair of bimorph piezoelectric elements opposite to the magnetic head are pivotally connected to a support base, and the magnetic head contact/separation means has a curved plane that is connected to the pair of bimorph piezoelectric elements. It consists of a third bimorph piezoelectric element perpendicular to the curved displacement plane of the piezoelectric element, and one end of this third bimorph piezoelectric element is fixed to the support base, and the other free end is connected to the pair of bimorph piezoelectric elements. Magnetic head displacement device in contact with the bottom surface. (3) In claim 1, the pair of bimorph piezoelectric elements are supported on a support base via a laminated piezoelectric element as a magnetic head contact/separation means whose thickness is changed depending on an applied voltage, and the laminated piezoelectric elements are A magnetic head displacement device in which the entire device moves toward and away from a magnetic recording medium via a type piezoelectric element.