JPH07105026B2 - Head actuator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording track for a head, which is used for an automatic tracking device such as a VTR (video tape recorder) by expanding and contracting motion of a bimorph element composed of a piezoelectric body and an elastic shim material by an applied voltage. along,
The present invention relates to a fixing method at a fixed end of a head actuator which is displaced in a predetermined direction.

[0002]

2. Description of the Related Art In recent years, a high-performance head actuator for recording / reproducing an image signal has been required in order to improve the function and image quality of a recording / reproducing apparatus such as a VTR.

A conventional magnetic head device will be described below. FIG. 9A is a partially cutaway perspective view showing an outline of a conventional magnetic head device disclosed in Japanese Patent Laid-Open No. 55-139630.

In FIG. 1 (a), a rotary head type helical scan type VTR is generally arranged on a magnetic tape wound around a head drum at a constant inclination angle according to the running speed of the tape and the rotating speed of the rotary head. An inclined recording track T (solid line) is formed as shown in FIG. However, when reproducing the magnetic signal on the magnetic tape at a speed different from the recording speed such as still, slow motion, double speed, or reverse mode, the scanning locus of the magnetic head is scanned at an inclination different from that of the recording track. The magnetic head moves off the recording track and scans along the dotted line in FIG. For this reason, guard band noise and crosstalk have been a problem.

Therefore, the above rotary head type VTR is provided with a head actuator for tracking so that the magnetic head accurately scans the recording track in various variable speed modes. For example, there is a head actuator using a bimorph plate as shown in FIG.

The structure and operating principle of the head actuator will be described below with reference to FIG. Reference numeral 21 is a bimorph plate, 22 is a head base, 23a and 23b are piezoelectric ceramics constituting the bimorph plate 21, and 24 is a central reinforcing metal plate which also serves as an intermediate electrode. In the figure, a magnetic head 25 is attached to a bimorph plate 21 having a cantilever structure fixedly supported by a fixed portion such as a head base 22. In the fixed portion side portion 21B of the bimorph plate 21, the piezoelectric ceramics 23a and 23b are connected to the central reinforcing metal plate 24.
The front end portion side portion 21A is pasted with an adhesive without the central reinforcing metal plate 24. Bimorph plate 21 configured as described above
The electrodes 26 and 27 provided on the outer surface of the piezoelectric ceramic of the portion 21B where the central reinforcing metal plate 24 is interposed cause the bimorph plate 21 to bend and displace in the direction C shown in FIG. Electrode 2 on ceramic
8 and 29 drive the 21A portion of the bimorph plate 21 so as to be displaced in the same direction.

With the above structure, the relative positions of the magnetic head 25 and the magnetic tape 30 are changed by the flexural displacement of the electrodes 26 and 27, and the bimorph plate 21 is changed by the electrodes 28 and 29.
Is displaced in the direction of the magnetic tape 30. As a result, since the gap between the magnetic tape 30 and the magnetic head 25 is always kept constant, the contact pressure is stabilized and the decrease in the recording / reproducing signal due to the tracking of the magnetic head 25 can be prevented. However, the problem of deterioration of the recording / reproducing signal due to the spacing angle caused by the inclination of the magnetic head 25 and the magnetic tape 30 has not been solved.

In order to solve the above problem, Japanese Patent Laid-Open No. 57-
There is a head actuator disclosed in Japanese Patent No. 60528. Details will be described below with reference to FIG. 11.

In FIG. 11, 31 is a first bimorph board, 32 is a second bimorph board, and 33 is a first electric machine in which a first bimorph board 31 is sandwiched by a second bimorph board 32 at a fixed end. A mechanical conversion element, 34 is a third bimorph plate, 35 is a fourth bimorph plate, 36 is a second electro-mechanical device in which the third bimorph plate 34 is sandwiched by the fourth bimorph plate 35 at its fixed end. A conversion element, 37 is a head support member having a U-shaped cross section, which connects the free ends of the first and second electro-mechanical conversion elements, and 38 is a head support member 3.
7 is a magnetic head attached on top of 7.

In the head actuator shown in the same figure, an electric field is applied to each piezoelectric ceramic so as to extend the piezoelectric ceramics on the a side and contract the piezoelectric ceramics on the b sides that form the first to fourth bimorph plates. Moreover, when deforming in the opposite direction, an electric field opposite to the above is applied. Accordingly, the first and second electromechanical conversion elements can be displaced in the direction indicated by C in FIG. 11 in accordance with the direction of the electric field.

In general, the displacement amount ξ (equation 1) of the bimorph plate
And the resonance frequency f (Equation 2) are shown by the following relationship.

[0012]

[Equation 1]

[0013]

[Equation 2]

Where d31 is the piezoelectric constant, l is the piezoelectric length,
t is the thickness of the piezoelectric body, ρ is the density of the piezoelectric body, and s11 is the elastic modulus of the piezoelectric body. From the relations of the above (Equation 1) and (Equation 2), there is a relation that the resonance frequency and the displacement amount are decreased when the other is increased.

However, with the above structure, the displacement obtained by the first and second bimorph plates 31 and 34 is enlarged by the second and fourth bimorph plates 32 and 35, and
It is possible to obtain a large displacement without lowering the resonance frequency of the electro-mechanical conversion element. Moreover, since the magnetic head 39 can be moved in parallel with the magnetic tape by the head supporting member 38 that connects the first and second electro-mechanical conversion elements to each other, the magnetic head 39 and the magnetic tape can be moved in parallel. The pacing angle can be made almost zero, and the deterioration of the recording / reproducing signal can be greatly improved.

[0016]

However, in the above-described conventional head actuator, since the piezoelectric body forming the bimorph plate is directly fixed to the base or the fixed base, when the bimorph plate is driven, it is fixed to the fixed portion of the piezoelectric body. This is a major problem in terms of reliability because stress is concentrated and damage due to cracks and the like easily occurs.

Further, since the piezoelectric ceramic naturally hangs down due to its own weight and the mass of the magnetic head, the position of the magnetic head with respect to the magnetic tape changes with time, which causes a problem in controlling the position of the magnetic head.

Further, since the piezoelectric body is easily damaged, it is difficult to realize uniform fixing, and the resonance frequency and the amount of displacement greatly vary depending on the fixed state and the fixed condition, so that there are serious problems in the stability of the characteristics and the productivity.

An object of the present invention is to provide a head actuator that solves the above problems.

[0020]

In order to achieve this object, a head actuator of the present invention is a bimorph element in which a first piezoelectric body and a second piezoelectric body are bonded together via an elastic shim material, and at least a bimorph element is provided. On the fixed end side of the element, the elastic shim material is attached so as to project from the first and second piezoelectric bodies, and the elastic shim material portion of the portion projecting from the piezoelectric body is completely fixed by the fixing base. The problem is solved by providing a structure in which a part of the first and second piezoelectric bodies is elastically supported and fixed.

[0021]

With the structure of the present invention, a new structure is adopted in which the piezoelectric body is elastically supported and fixed without being directly fixed by the fixing base, and the elastic shim member is completely fixed, which is caused by the deformation of the bimorph element. It is possible to eliminate stress concentration between the piezoelectric body and the fixed end of the fixed base.

Further, since the elastic shim member made of a metal material or a carbon fiber-based material is completely fixed to elastically support the piezoelectric body, stress concentration at the fixed end of the piezoelectric body is relieved and the position is securely fixed. The position of the magnetic head with respect to the magnetic tape can be assured with high accuracy within the elastic range of the elastic shim member.

Further, since the completely fixed portion is formed inside the fixed base, the piezoelectric body is not completely fixed, so that a large amount of displacement can be obtained, and the resonance frequency is approximately from the fixed end portion of the piezoelectric body of the bimorph element to the free end portion thereof. It is possible to obtain a head actuator having a high resonance frequency because it is determined by the length.

[0024]

EXAMPLE 1 Example 1 of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a head actuator according to a first embodiment of the present invention. In the figure, 1 is a first piezoelectric body, 2 is a second piezoelectric body, 3 is an elastic shim material, and 4 is a first piezoelectric body.
Of the piezoelectric body 1 and the second piezoelectric body 2 bonded to both sides of the elastic shim material 3, a bimorph element 5 is a fixing base for fixing the bimorph element 4, 6 is a head supporting member, and 7 is a magnetic head. .

In the figure, the first and second piezoelectric bodies 1, 2
At least in the direction of deformation, the elastic shim material 3 made of a metal material such as phosphor bronze, invar, titanium or the like, or a carbon fiber-based material, excluding the fixing portion 3a of the elastic shim material. Then, the bimorph element 4 is formed by adhering the same to the above. The fixing portion 3a of the elastic shim material of the bimorph element 4 is completely fixed on the fixing base 5 with screws or the like.

On the other hand, from the fixed end of the bimorph element 4 of the fixed base 5, the piezoelectric body portion and the elastic shim portion inside the fixed base 5 are supported and fixed by an elastic member 8 such as an epoxy adhesive. Then, the head support member 6 is bonded and fixed to either one of the piezoelectric surfaces to the free end of the bimorph element 4 as shown in the figure, and the magnetic head 7 is provided at the tip thereof.

Although the elastic member 7 is an epoxy adhesive in the embodiment, a material having a smaller elastic modulus than the piezoelectric body,
For example, any material such as a hard rubber material or a plastic material may be used. Further, the mounting position of the magnetic head 7 is not limited to the position of this embodiment, and it may be mounted on the lower surface of the head supporting member 7, for example, but it is preferable to dispose on the extension line of the elastic shim member 3. Is.

Next, the operation principle will be described with reference to the operation explanatory diagrams of FIGS. 2 (a), 2 (b) and 2 (c). In FIG. 3B, the polarization axes of the first piezoelectric body 1 and the second piezoelectric body 2 are oriented toward the elastic shim member 3 as shown in the figure. Here, when an electric field is applied in the polarization axis direction, the piezoelectric body expands in the polarization axis direction, so that the piezoelectric body contracts in the length direction and is displaced upward as shown in FIG. In the opposite case, the opposite displacement occurs as shown in FIG.

As a result, when an electric field is applied between the electrodes outside the first piezoelectric body and the second piezoelectric body, the bimorph element 4 is vertically displaced in the C direction in the figure depending on the polarity of the applied electric field. Will be done. However, since a piezoelectric body usually has a coercive electric field (electric field strength at which the piezoelectricity disappears), the above-mentioned driving method is not used, but only one-sided driving in which only the electric field in the polarization direction is applied or within the coercive electric field. A diode is provided so as to apply an electric field up to and the first and second piezoelectric bodies are driven up to the coercive field, and the bimorph element 4 is displaced by one-sided driving at an electric field higher than that.

As described above, according to the first embodiment of the present invention,
Part of the first and second piezoelectric bodies of the bimorph element 4 is not directly fixed by the fixing base 5, but is supported and fixed by the elastic member 8 such as an adhesive, and the fixing portion 3a of the elastic shim material is completely fixed by the fixing base 5. By doing so, the stress concentration generated at the fixed end portion of the piezoelectric body and the fixing base due to the deformation of the bimorph element 4 can be relaxed, and therefore the flexural deformation can be allowed up to the strain limit of the piezoelectric body attached to the bimorph element 4, so that a large displacement In addition to obtaining a large amount, cracks and the like do not occur in the piezoelectric body, so that an excellent head actuator with very few variations in reliability and characteristics can be obtained.

Further, since the bimorph element is completely fixed by the fixing portion 3a of the elastic shim material, the bimorph element is deformed due to the deformation of the shape of the piezoelectric element due to the weight of the fixed element of the piezoelectric element and the stress caused by the mass of the head, which are generated in the conventional structure. By eliminating the occurrence of sag that does not accompany the distortion of the element, the position of the magnetic head with respect to the magnetic tape can always be maintained with high accuracy within the elastic limit of the elastic shim material completely fixed by the fixing base.

Furthermore, since the completely fixed portion is formed inside the fixed base, the deformation of the bimorph element due to the piezoelectric effect of the piezoelectric body occurs from the inside of the fixed end as the starting point, so that the amount of displacement can be easily expanded. Further, since the resonance frequency is determined by the length from the fixed end portion to the free end portion of the bimorph element, the contradictory relationship between the resonance frequency and the displacement amount can be improved, and a higher performance head actuator can be obtained.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings.

The second embodiment is the same as the first embodiment as shown in FIG.
In the structure of the head actuator, the elastic shim material 3 at the free end portion of the bimorph element 4 is formed longer than the first and second piezoelectric bodies 1 and 2, and a sticking portion 3b is provided, and the sticking portion 3b and the bimorph element are provided. 4 is a head actuator in which the head support member 6 is attached to both surfaces of the piezoelectric body by adhesion or the like, and the magnetic head 7 is attached to the head support member 6, and other configurations are the same as in the first embodiment. .

As described above, according to the second embodiment of the present invention,
The same effect as that of the first embodiment is obtained, and the instability of the adhesive strength between the head supporting member 6 and the piezoelectric body of the bimorph element 4 in the first embodiment is reduced by the sticking portion 3b of the elastic shim material 3
By attaching the head support member to both the piezoelectric body and the piezoelectric body, the adhesive shim material 3 having an increased adhesive area and good adhesiveness is used to significantly improve the adhesive strength and pull the adhesive portion due to the deformation of the bimorph element. The reliability against load fluctuation due to repeated compression and compression is significantly improved.

Further, when the head support member 6 is attached to the piezoelectric body, the head support member 6 is surely positioned by the attachment portion 3b of the elastic shim material 3 and the piezoelectric body when the head actuator length changes due to the variation in the bonding position. Because you can
The attachment adjustment of the magnetic head 7 can be simplified, and the productivity can be greatly improved.

Needless to say, the head supporting member 6'of the portion of the bimorph element that is bonded to the piezoelectric body may have the structure shown in FIG. Further, the mounting position of the magnetic head 7 and the mounting shape of the head supporting member 6 ′ are not particularly limited to the structure of this embodiment.

(Third Embodiment) FIG. 5 is a sectional view of a head actuator according to a third embodiment of the present invention. In the figure,
In the third embodiment, two sets of head actuators including the bimorph element, the head supporting member, and the magnetic head of the first embodiment are used so as to be parallel to each other, and the respective free ends are connected via the head supporting member or the like. A magnetic head is provided, and this configuration produces a great effect which is not available in the first embodiment.

The third embodiment of the present invention will be described below with reference to the drawings. 9 is the first piezoelectric body, 10 is the second
, A first elastic shim member 12, and a first bimorph element 12 in which the first piezoelectric member 9 and the second piezoelectric member 10 are bonded to both surfaces of the first elastic shim member 11. , 13 is a third piezoelectric body, 14 is a fourth piezoelectric body, 15 is a second elastic shim material, 16 is a third piezoelectric body 13 and a fourth piezoelectric body 14.
Is attached to both surfaces of the second elastic shim material 15, a second bimorph element is provided, 17 is a fixing base for fixing the first and second bimorph elements, and 18 is a connection between the first and second bimorph elements. Reference numeral 19 denotes a magnetic head which is a head supporting member.

In the figure, the first and second piezoelectric bodies 9, 1
The first and second piezoelectric bodies 13 and 14 are made of a metal material such as phosphor bronze, Invar or titanium, or a carbon fiber-based material having a high elastic modulus at least in the deformation direction. The first and second bimorph elements 12 and 16 are formed on both surfaces of the elastic shim materials 11 and 15 by adhering the elastic shim materials to portions other than the fixing portions 11a and 15a by adhesion or the like. The first and second bimorph elements 12, 16
Fixing portions 11a of the first and second elastic shim members 11 and 15 of
15a are provided so as to be parallel to each other and are fixed to the fixing base 17 completely by using screws or the like.

On the other hand, from the fixed end portions of the first and second bimorph elements 12 and 16 of the fixing base 17 to the piezoelectric body portion and the elastic shim portion inside the fixing base 17, the elastic member 20 such as an epoxy adhesive is used. Support and fix with.

Next, the first and second bimorph elements 1
The free ends 2 and 16 are connected in parallel to each other by adhesively fixing the head support member 18 to one of the piezoelectric bodies, and the magnetic head 19 is provided at the tip thereof.

Although the elastic member 20 is the epoxy adhesive in the third embodiment, any material may be used as long as it has a smaller elastic modulus than the piezoelectric body, such as a hard rubber material or a plastic material. Further, the mounting position of the magnetic head 19 is not limited to the position of this embodiment, but may be mounted on the upper surface of the head supporting member 18, but preferably between the first and second bimorph elements 12 and 16. It is best to install it on the extension line in the center of.

Next, the operation principle will be described with reference to the operation explanatory diagrams of FIGS. 6 (a), 6 (b) and 6 (c). In this figure, the basic operation principle is the same as that described in FIG. 2, and the operation newly added in the third embodiment will be described below.

From FIGS. 6 (a) and 6 (c), the length of the bent portion 18a of the head supporting member 18 provided so as to connect the free ends of the first and second bimorph elements is first and second. Two
Since it does not change even when the bimorph element of is deformed,
As shown in the figure, the magnetic head 19 is
Move in parallel. As a result, the spacing angle between the magnetic head 19 and the magnetic tape becomes substantially zero, so that the deterioration of the recording / reproducing signal can be prevented.

As described above, according to the third embodiment of the present invention,
By adopting the fixed part structure of the bimorph element, the same effect as that of the first embodiment can be obtained.

By connecting the two sets of bimorph elements in parallel by the head supporting member, the spacing angle between the magnetic head and the magnetic tape can be made substantially zero, so that the deterioration of the recording / reproducing signal can be prevented and It is possible to obtain a head actuator with high performance and high image quality. Further, the parallel structure of the two sets of bimorph elements can greatly reduce the influence of the load such as the head mass on the characteristics such as the reduction of the resonance frequency. In addition, the twisting of the magnetic head caused by the deformation in the direction orthogonal to the bending deformation caused by the thickness variation of each piezoelectric body and the variation of the bonding state between the elastic shim material and the piezoelectric body is caused by the parallel structure. By the same correction effect as in the principle described above, it is possible to obtain a head actuator in which the position of the magnetic head is always stable and the mounting adjustment such as correction of the relative position to the magnetic tape is easy.

(Embodiment 4) Hereinafter, Embodiment 4 of the present invention will be described with reference to the drawings.

The fourth embodiment is the same as the third embodiment as shown in FIG.
In the structure of the head actuator described above, the first and second elastic shim members 11 and 15 at the free ends of the first and second bimorph elements 12 and 16 are connected to the first and second piezoelectric elements and the third and fourth piezoelectric elements. Formed longer than the bodies 9, 10 and 13, 14 and provided with sticking portions 11b, 15b, and these sticking portions 11b, 15b
And a head support member 18 shown in the drawing is attached to both the surfaces of the piezoelectric bodies of the first and second bimorph elements 12 and 16 by adhesion or the like, and a magnetic head 19 is attached to the head support member 18. The other head actuator is the same as that of the third embodiment.

As described above, according to the fourth embodiment of the present invention,
The same effect as that of the third embodiment can be obtained, and the instability of the adhesive strength between the head support member 18 and the piezoelectric bodies of the first and second bimorph elements 12 and 16 in the third embodiment can be reduced to the first.
And the attaching portions 11b, 15 of the second elastic shim members 11, 15
By attaching the head support member 18 to both b and the piezoelectric body, the adhesive strength is significantly improved by increasing the adhesive area and adopting the elastic shim material having good adhesiveness, and the adhesive portion due to the deformation of the bimorph element is improved. The reliability of load fluctuation due to repeated tension and compression is significantly improved.

In addition, when the head support member is attached to the piezoelectric body, the head support member can be reliably positioned by the attachment portion of the elastic shim material and the piezoelectric body when the head actuator length changes due to variations in the bonding position. Head mounting adjustment can be simplified and productivity can be greatly improved.

Further, by providing the head support member on the elastic shim material near the neutral surface of the deformation of the bimorph element,
The gap between the magnetic tape and the magnetic head (hereinafter referred to as the protrusion amount) caused by the deformation of the magnetic head can be eliminated by the deformation direction of the head actuator, and the absolute value of the protrusion amount can be reduced. Because you can
The deterioration of the recording / reproducing signal due to the positional relationship between the magnetic head and the magnetic tape can be greatly improved.

Needless to say, the head supporting member 18 'which is bonded to the piezoelectric body of the bimorph element may have the structure shown in FIG. Further, the mounting position of the magnetic head 19 and the mounting shape of the head supporting member 18 'are not particularly limited to the structure of this embodiment.

[0055]

As described above, according to the present invention, the piezoelectric body itself is not directly fixed to the fixing base but is elastically supported and fixed by an elastic member such as an adhesive, and the elastic shim member is completely fixed to the fixing base. As a result, it is possible to eliminate stress concentration between the piezoelectric body and the fixed end portion of the fixing base, which is generated by the deformation of the bimorph element, so that a highly reliable head actuator can be obtained.

Further, since the elastic shim member made of a metal material or a carbon fiber-based material is completely fixed to the fixing base, deformation of the piezoelectric body itself caused by stress due to its own weight on the fixed end of the piezoelectric body or head mass is caused. There is nothing, and the absolute position of the magnetic head with respect to the magnetic tape can be guaranteed with high accuracy within the elastic range of the elastic shim material.

Further, since the complete fixing portion made of the elastic shim material of the bimorph element is formed inside the fixing base, the deformation of the bimorph element due to the piezoelectric effect of the piezoelectric body occurs from the inside of the fixed end, so that the displacement amount can be expanded. Since the resonance frequency is determined by the length from the fixed end to the free end of the bimorph element, a head actuator having a high resonance frequency can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a head actuator according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an operating principle of the head actuator of the embodiment.

FIG. 3 is a sectional view of a head actuator according to a second embodiment of the present invention.

FIG. 4 is a view showing an example of another head supporting member which can be used in the embodiment.

FIG. 5 is a sectional view of a head actuator according to a third embodiment of the invention.

FIG. 6 is a view showing the operating principle of the head actuator of the same embodiment.

FIG. 7 is a sectional view of a head actuator according to a fourth embodiment of the present invention.

FIG. 8 is a diagram showing an example of another head support member that can be used in the same embodiment.

FIG. 9 is a partially cutaway perspective view schematically showing a conventional magnetic head device.

FIG. 10 is a cross-sectional view of a conventional head actuator.

FIG. 11 is a cross-sectional view of another conventional head actuator.

[Explanation of symbols]

 1, 9, 13 First piezoelectric body 2, 10, 14 Second piezoelectric body 3 Elastic shim material 11 First elastic shim material 15 Second elastic shim material 3a, 11a, 15a Fixed portion of elastic shim material 3b, 11b, 15b Attachment part of elastic shim material 4 Bimorph element 12 First bimorph element 16 Second bimorph element 5, 17 Fixing stand 6, 18 Head support member 7, 19 Magnetic head 8, 20 Elastic member 21, 31 , 32 bimorph plate 24 central reinforcing metal plate 33, 37 electro-mechanical conversion element

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsushi Takeda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Masanori Sumihara 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Osamu Kawasaki 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-57-60528 (JP, A) JP-A-60-133523 (JP, A) JP-A Sho 56-83983 (JP, A) Actual opening Sho 55-19392 (JP, U) Actual opening Sho 60-77012 (JP, U)

Claims (4)

[Claims] 1. A bimorph element in which a first piezoelectric body having electrodes formed on the upper and lower surfaces in the polarization axis direction and a second piezoelectric body are bonded to each other through an elastic shim material, and at least at a fixed end of the bimorph element. The elastic shim member formed longer than the first and second piezoelectric bodies is completely fixed by a fixing base, and a part of the first and second piezoelectric bodies is elastically supported and fixed;
A head actuator, wherein a magnetic head is provided at a free end of the bimorph element via a head supporting member. 2. At the free end of the bimorph element, an elastic shim is formed longer than the first and second piezoelectric bodies, and a head support member is provided on both the elastic shim material and the surface of at least one of the piezoelectric bodies. The head actuator according to claim 1, which is laminated. 3. A first bimorph element in which a first piezoelectric body having electrodes formed on the upper and lower surfaces in the polarization axis direction and a second piezoelectric body are bonded to each other via a first elastic shim material, and a third bimorph element. A second piezoelectric body and a fourth piezoelectric body are bonded together via a second elastic shim material.
A bimorph element of at least the first and second
At the fixed end of the bimorph element, the first and second elastic shim members formed longer than the first, second, third and fourth piezoelectric bodies are completely fixed by a fixing base so that they are parallel to each other. The first and second piezoelectric bodies and a part of the third and fourth piezoelectric bodies are elastically supported and fixed, and the free ends of the first and second bimorph elements are fixed to a head support member. A head actuator, characterized in that the head fixing member is provided with a magnetic head connected to each other via a magnetic head. 4. The first and second elastic shim members are formed longer than the first and second piezoelectric bodies and the third and fourth piezoelectric bodies at the free ends of the first and second bimorph elements. A head supporting member connecting the first and second bimorph elements to each other is provided with the first and second elastic shim members and at least one of the piezoelectric surface of the first and second bimorph elements. The head actuator according to claim 3, which is attached to both.