JPS62146425A - Magnetic head displacing device - Google Patents

Abstract

PURPOSE:To prevent a magnetic head from inclination and separation from a medium by connecting a pair of bimorph piezoelectric elements so that their bending directions are reversed to each other and arranging a piezoelectric element to be expanded/contracted between one bimorph piezoelectric element and a supporting board. CONSTITUTION:A pair of bimorph piezoelectric elements 18f, 18r fitting a magnetic head 20 are connected so that the polarizing direction of piezoelectric elements 11f, 12f is reversed from that of piezoelectric elements 11r, 12r. On the other hand, the laminate pizoelectric element 31 to be expanded by impressing a voltage is arranged between the element 18r and the supporting board 19. When voltage is impressed between curved electric terminals 22, 23 in said constitution, the elements 18f, 18r are bent so that respective bending directions are reversed and the head 20 is vertically moved without being inclined from the recording medium 20. Although the head 20 is separated from the medium 24 because of the movement, the separation can be compensated by impressing a voltage to the piezoelectric element 31.

Description

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 flexible metal substrate sandwiched between them. The substrate serves as one electrode terminal, and the terminal connecting the piezoelectric elements on both sides serves as 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 a voltage across both terminals. At this time, the amount of deflection of the free end can be controlled by the magnitude of the applied voltage, and the direction can be controlled by changing the polarity.

Therefore, by using this bimorph piezoelectric element, it is possible to construct a tracking control device for, for example, a video tape recorder (VTR).

FIGS. 4 and 5 show conventional examples thereof. 1 in the diagram
Reference numeral 1.12 denotes a piezoelectric element made of a piezoelectric ceramic material such as PzT type, and an electrode 13.14 and an electrode 15.16 are respectively adhered to each main surface (both sides) of this pixel element 11.12. . 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 the two piezoelectric elements, and these are laminated and bonded with adhesive to form a bimorph piezoelectric element 18. It is formed.

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. Helad gap portion 21 of this magnetic head 20
protrudes from the free end of the bimorph piezoelectric element 18. 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 electric terminal 22 connecting the electrode 16 of the piezoelectric element 12 and the same terminal 23 connected to the flexible metal substrate 17, stress is generated in the piezoelectric elements 11 and 12. Since the flexible metal J5 plate 17 has flexibility, the entire bimorph piezoelectric element 18 curves, 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 1 shown by the chain line in FIG.
8 (magnetic head 20) is an exaggerated illustration of the position after displacement by applying a driving voltage.

However, in this conventional device, when the bimorph piezoelectric element 18 is bent, as is clear from 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 positional relationship between the two and causes deterioration of recording and reproducing characteristics.

``Object of the Invention'' The present invention solves the above problems and provides a magnetic displacement device using a bimorph piezoelectric element.

A device that maintains the optimal positional relationship between the magnetic head and recording medium even during tracking correction, without causing the magnetic head to separate from the recording medium when a driving voltage is applied, and preventing the magnetic head from tilting relative to the recording medium. The purpose is to obtain.

"Summary of the Invention" The present invention solves the problem of the magnetic head (bimorph piezoelectric element) separating from the recording medium by providing a removable stacked piezoelectric element between the bimorph piezoelectric element and its support base. Solved by intervening.

Furthermore, the problem of the magnetic head being tilted with respect to the recording medium is solved by connecting a pair of bimorph piezoelectric elements that curve in opposite directions using the same drive voltage.

"Embodiments of the Invention" The present invention will be described below with reference to illustrated embodiments. A pair of bimorph piezoelectric elements 18f and 18r used in the present invention are formed in front and behind a common flexible electrode substrate 30. The bimorph piezoelectric element 18f is an element to which the same magnetic head 20 as in the conventional device is fixed at its tip, and the bimorph piezoelectric element 18r is an element whose base is connected to the support base 19 via the laminated piezoelectric element 31. is 0
The structures of both piezoelectric elements themselves are the same as those explained in FIGS. 3 and 4, so FIGS.
The symbols f and r are added to the symbols of the elements explained in the figures, respectively.

This pair of bimorph piezoelectric elements t 8 f, 18
In r, the polarization direction of the piezoelectric elements 11f and 12f and the polarization direction of the piezoelectric elements fir and 12r are reversed, and the electrode 13f and the electrode 13r, and the electrode 16f and the electrode 16r are connected by connecting wires 32 and 33, respectively. Therefore, when a driving voltage is applied between the curved electric terminals 22 and 23, they curve 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.

A laminated piezoelectric element 31 is interposed between the bimorph piezoelectric element 18r and the support base 19. That is, the rear end of the bimorph piezoelectric element 18r is fixed to the support plate 36, and the support plate 36 and the support base 19 are connected by the laminated piezoelectric element 31. This laminated piezoelectric element 31
3 changes the amount of expansion in the direction of the arrow in FIG. 3 depending on the magnitude of the voltage applied through the telescopic electric terminals 37 and 38. When the voltage is removed, it contracts and becomes the shortest length.

In the water device configured as described above, when a voltage is applied between the curved electrical terminals 22 and 23, the same voltage is applied to the bimorph piezoelectric elements 18f and 18r via the connecting wires 32 and 33. For this reason, the pixel elements are curved in different directions. Since the pixel elements have the same length, the amount of curvature (distortion) occurs in the same way even if the direction is reversed. Therefore, as shown in FIG. It maintains a perpendicular relationship and does not tilt.As mentioned above, the amount of curvature depends on the magnitude of the applied voltage, and the direction depends on the polarity, so by applying a voltage according to the tracking deviation. , this can be corrected.

On the other hand, by applying a voltage between the curved electrical terminals 22, 23 in this way, the bimorph piezoelectric elements 18f, 18. When r is bent, the magnetic head 20 separates from the recording medium 24. In order to correct this, an appropriate voltage is applied to the laminated piezoelectric element 31 via the telescopic electrical terminals 37, 38. In other words, due to the curvature of the bimorph piezoelectric elements 18f and 18r, 711!
A voltage is applied to cause the laminated piezoelectric element 31 to elongate in the direction opposite to the length by which the air head 20 separates from the recording medium 24 . Basically, this voltage can be changed in magnitude depending on the magnitude of the voltage applied between the curved electrical terminals 22 and 23.
This prevents the magnetic head 20 from separating from the recording medium 24, and even when tracking correction is performed, it is possible to always maintain the optimum relationship between the magnetic head 20 and the recording medium 24.

"Effects of the Invention" As described above, in the present invention, a pair of bimorph piezoelectric elements are connected in series so that their curvature directions are opposite, and a magnetic head is provided at the tip of the bimorph piezoelectric elements. The magnetic head does not tilt with respect to the recording medium, and a multilayer piezoelectric element that expands when a voltage is applied is interposed between the bimorph piezoelectric element and its support. Since the magnetic head is designed to compensate for the separation of the magnetic head from the recording medium, the magnetic head does not separate from the recording medium, and therefore, the correct positional relationship between the magnetic head and the recording medium is always maintained to perform more preferable recording and reproduction. I can do it.

[Brief explanation of drawings]

1st [i! J is a perspective view showing an embodiment of the magnetic head displacement device according to the present invention, FIG. 2 is a front view thereof, FIG. 3 is a perspective view of a laminated piezoelectric element, and FIG. 4 is an example of a conventional magnetic head displacement device. The perspective view shown in FIG. 5 is a front view of the same. 11f, llr, 12f, 12r...-piezoelectric element,
13f, 13r, 14f, 14r, 15f
, 15r, 16f, 16 r-electrode, 18f, 18
r-bimorph piezoelectric element, 19... support stand, 20.
...Magnetic head, 22.23...Curved electrical terminal, 30
... Flexible metal substrate, 31 ... Laminated piezoelectric element, 3
7.38... Telescopic electrical terminal. Patent Applicant Asahi Optical Industry Co., Ltd. Agent Kunio Miura Shigeru Matsui Figure 1 Figure 4 Figure 5 rM Procedural Official Letter (Spontaneous) February 10, 1986 Commissioner of the Patent Office Michibu Uga 1. Indication of the incident 1985 Patent Application No. 287460 2) Name of the invention Magnetic head displacement device Representative Toru Matsuki 4. Attorney Drawing 6. Details of the amendment Figures 1 and 2 of the drawing are attached. Correct the drawing. that's all

Claims (2)

[Claims] (1) In a magnetic head displacement device in which a bimorph piezoelectric element that changes the amount and direction of curvature by changing the magnitude and polarity of an applied voltage and a magnetic recording medium are arranged almost perpendicularly to each other, and a magnetic head is fixed to the tip of the bimorph piezoelectric element, A pair of bimorph piezoelectric elements are connected so that their bending directions are opposite to each other, and a magnetic head is fixed to the tip of one of the bimorph piezoelectric elements, and between the base of the other bimorph piezoelectric element and its support base. A magnetic head displacement device characterized by interposing a laminated piezoelectric element that expands and contracts depending on the magnitude of applied voltage. (2) The magnetic head displacement device according to claim 1, wherein the pair of bimorph piezoelectric elements share a flexible metal substrate sandwiched between each pair of piezoelectric elements.