JPH09171614A - Actuator and magnetic head device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the manufacturing cost and the assembly cost. SOLUTION: This device using this actuator is composed of a 1st member 31 consisting of an electromechanical transducing element, 2nd members 32a and 32b consisting of electromechanical transducing elements disposed to hold one end of the 1st member 31 between them, a 3rd member 35 consisting of an elastic material, a 1st holding means 316 for combining and holding each individual one end of the 2nd and 3rd members 32a, 32b and 35 and a 2nd holding means 34 for combining and holding the other ends of the 1st and 3rd members 31 and 35. In this case, the 1st, 2nd and 3rd members 31, 32a, 32b and 35 are curved with the 1st holding means 316 as a fixed fulcrum to oscillate the 2nd holding means 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator used in a video tape recorder (VTR) capable of variable speed reproduction such as slow reproduction and reverse reproduction, and a magnetic head device to which the actuator is applied.

[0002]

2. Description of the Related Art Since the transfer speed of the magnetic tape during the variable speed reproduction of the above-mentioned VTR is different from the transfer speed of the magnetic tape during the recording, the recording speed of the magnetic tape is changed during the variable speed reproduction. There is a difference between the angle and the tracking locus of the magnetic head. Therefore, the magnetic head is oscillated in the width direction of the recording track, the position (height) of the magnetic head is displaced to correct the angular difference, and the magnetic head can follow the recording track. Dynamic Track
ing) head device is used in the rotary magnetic head device of the VTR. As an actuator for swinging a magnetic head applied to this DT head device, a cantilever structure having a bimorph, which is an electromechanical conversion element such as a piezoelectric element, is often used.

By the way, in a so-called digital VTR,
A recording method using a large number of recording tracks for one field video signal is adopted. Therefore, when performing variable speed reproduction with such a digital VTR, the magnetic head must be displaceable for many recording tracks. That is, the actuator applied to the DT head device of the digital VTR is compared with the actuator applied to the DT head device of the recording type VTR which uses one recording track for one field video signal. , The amount of displacement needs to be large.

Further, in the digital VTR, since a large number of recording tracks are used as described above, a magnetic tape having a narrow recording track width is used. Therefore, in order to improve the reproducibility of the reproduced signal when performing variable speed reproduction with such a digital VTR, it is necessary to control the tracking with higher accuracy. That is, the actuator applied to the DT head device of the digital VTR has one
The displacement control accuracy is required to be higher than that of an actuator applied to a DT head device of a VTR of a recording system that uses one recording track for a field image signal.

Further, in the digital VTR, since a large number of recording tracks are used as described above, the rotational speed of the rotary drum of the rotary magnetic head device has been increased. Therefore, when performing variable speed reproduction with such a digital VTR, tracking control at a high frequency is necessary. That is, the actuator applied to the DT head device of the digital VTR is a recording type VT that uses one recording track for one field image signal.
The displacement control frequency needs to be higher than that of the actuator applied to the R DT head device.

FIG. 4 is a perspective view showing an example of a DT head device to which such an actuator is applied. In this DT head device 10, a rectangular portion of a bimorph 11 having a trapezoidal shape and a rectangular shape is sandwiched between two auxiliary bimorphs 12a and 12b having the same shape as the rectangular shape, and a magnetic head 13 is provided at the tip thereof. Is attached, and a conductive holder 14 made of aluminum or brass is attached to the end.

The bimorph 11 is composed of two piezoelectric plates 111,
112 has a structure in which the intermediate electrode 113 is sandwiched and bonded to each other, and the surface electrodes 114 and 115 are formed on both surfaces of the bonded together. In addition, the auxiliary bimorph 12a,
12b also includes two piezoelectric plates 121a, 122a, 121.
b and 122b are bonded to each other with the intermediate electrodes 123a and 123b interposed therebetween, and the front surface electrode 12 is provided on both surfaces of the bonded electrodes.
4a, 125a, 124b, 125b are formed. A tip base 116 to which the magnetic head 13 is attached is attached to the tip of the bimorph 11. Also, the bimorph 11 and the auxiliary bimorph 1
The ends of 2a and 12b are sandwiched between a base holder 141 and a pressing holder 142 that form the holder 14.
In the holder 14 and the like configured as described above, an insulating plate is sandwiched between the base holder 141 and the rotary drum so that the magnetic head 13 is swingably arranged at the circumferential portion of the rotary drum. It is supported and fixed on the rotating drum by bolts.

In order to operate the DT head device 10 having such a structure to cause the magnetic head 13 to follow the recording track of the magnetic tape, the bimorph 11 and the auxiliary bimorph 1 are used.
2a, 12b, one of the piezoelectric plates 111, 121a, 121
b to the other piezoelectric plate 112, 122a, 122
b by contracting the bimorph 11 and the auxiliary bimorph 12
Curve a and 12b. Where the auxiliary bimorph 12
a and 12b are provided to obtain the large displacement amount and the high displacement control frequency described above.

However, when the bimorph 11 and the auxiliary bimorphs 12a and 12b are curved, an inclination angle is generated, which causes a problem that the contact state between the magnetic head 13 and the magnetic tape is deteriorated. Therefore, there has been proposed a DT head device to which an actuator having a structure in which two pairs of the bimorph 11 and the auxiliary bimorphs 12a and 12b are arranged in parallel is applied to suppress the inclination.

FIG. 5 is a perspective view showing an example of a DT head device to which such an actuator is applied. In this DT head device 20, two sets of the above-mentioned bimorph 11 and auxiliary bimorphs 12a and 12b are arranged in parallel, a magnetic head 13 is attached to the tip thereof, and a conductive holder 24 made of aluminum or brass is attached to the end thereof. It has been configured.

A chip base 117 to which a magnetic head 13 is attached is attached to the tips of the two sets of bimorphs 11. Further, the ends of the two sets of the bimorph 11 and the auxiliary bimorphs 12 a and 12 b are sandwiched between the base holder 141 and the pressing holder 142 with the middle holder 241 constituting the holder 24 sandwiched therebetween. In the holder 24 and the like configured as described above, an insulating plate is sandwiched between the base holder 141 and the rotating drum so that the magnetic head 13 is swingably arranged at the circumferential portion of the rotating drum. It is supported and fixed on the rotating drum by bolts.

According to the DT head device 20 having such a configuration, the two bimorphs 11 and the auxiliary bimorphs 12a and 12b are simultaneously curved in the same direction by the driving of the driving circuit, so that the bimorphs are arranged in parallel and both ends thereof are arranged. Two sets of bimorphs 11 and auxiliary bimorphs 12a, 12 that are connected
The curved shape of b is S-shaped. Therefore, the magnetic head 13
Moves in parallel with the rotation axis of the rotary drum, so that it can follow the recording tracks of the magnetic tape obliquely wound around the outer peripheral surface of the rotary drum during variable speed reproduction.

[0013]

According to the actuator applied to the latter DT head device 20 described above, since the tilt angle is not generated, the magnetic head 13 and the magnetic tape are not formed.
It is possible to maintain a good contact state of the cup. However, when this actuator is created, two sets of bimorphs 11 and auxiliary bimorphs 12a and 12b are required, and since they are used by being connected, it is necessary to select those having similar displacement amounts and resonance frequencies. Therefore, there is a problem that the manufacturing cost and the assembly cost increase.

In view of the above points, the present invention has an object to provide an actuator and a magnetic head device which are inexpensive to manufacture and assemble.

[0015]

According to the present invention, the above object is to provide a first member formed of an electromechanical conversion element and an electromechanical conversion element arranged so as to sandwich one end of the first member. A second member made of elastic material, a third member made of an elastic material, first holding means for holding one end of each of the second and third members by coupling, and the first and third members. A second holding means for connecting and holding the other ends of
This is achieved by bending the first, second and third members with the first holding means as a fixed fulcrum and swinging the second holding means.

According to the above construction, the first and second members made up of the electromechanical conversion elements, which are conventionally required in two sets, are replaced by the third member made of an elastic material, so that one set is sufficient, and It is not necessary to select those having the same displacement amount or the same resonance frequency.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The embodiments described below are preferred specific examples of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. It is not limited to these forms unless otherwise stated.

FIG. 1 is a schematic perspective view showing an embodiment of a DT head device to which an embodiment of the actuator of the present invention is applied. In this DT head device 30, a rectangular portion of a bimorph 31 having a trapezoidal shape and a rectangular shape is sandwiched between two auxiliary bimorphs 32a and 32b having the same shape as the rectangular shape, and aluminum or brass is provided at the end thereof. A conductive holder 34 made of, for example, is attached. The bimorph 31 and the leaf spring 35 having a cantilever structure coupled to the holder 34 are arranged in parallel,
The magnetic head 33 is attached to these tips.

In the bimorph 31 which is the first member, two piezoelectric plates 311 and 312 are bonded to each other with the intermediate electrode 313 sandwiched therebetween, and the surface electrode 31 is formed on both surfaces of the bonding.
4, 315 is formed. Also, the second
Also in the auxiliary bimorphs 32a and 32b, which are members of the above, the two piezoelectric plates 321a, 322a, 321b, and 322b are bonded to each other with the intermediate electrodes 323a and 323b sandwiched therebetween, and the surface electrodes 324a, 325a, and 3
It has a structure in which 24b and 325b are formed.

At the tip of the bimorph 31, the magnetic head 3
The chip base 316, which is the second holding means to which 3 is attached, is attached. Further, the ends of the bimorph 31 and the auxiliary bimorphs 32a and 32b are sandwiched by a base holder 341 and a pressing holder 342 which constitute a holder 34 which is a first holding means. Further, the tip base 316 is attached to the tip of the leaf spring 35, which is a third member parallel to the bimorph 31, and the leaf spring 35 is attached.
The end of is fixed to the base holder 341. That is, the base holder 341 is sandwiched between the auxiliary bimorph 32b and the leaf spring 35.

FIG. 2 is a schematic perspective view showing another embodiment of the DT head device to which the embodiment of the actuator of the present invention is applied. This DT head device 40 also has the same configuration as the DT head device 30 shown in FIG. 1, and the auxiliary portion of the bimorph 31 having a trapezoidal shape and a rectangular shape is the same shape as the rectangular shape. It is sandwiched between the bimorphs 32a and 32b, and a conductive holder 34 made of aluminum, brass, or the like is attached to this end. The bimorph 31 and the leaf spring 36 having a cantilever structure coupled to the holder 34 are arranged in parallel,
The magnetic head 33 is attached to these tips.

The bimorph 31 which is the first member, the auxiliary bimorphs 32a and 32b which is the second member, the holder 34 which is the first holding means and the chip base 317 which is the second holding means are shown in FIG. Although it has the same structure as the DT head device 30, the end of the leaf spring 36, which is the third member, is sandwiched and fixed between the auxiliary bimorph 32b and the base holder 341. With such a configuration, the leaf spring 36 is directly fixed to the auxiliary bimorph 32b, so that the tip base 317 can be made thin and lightweight. Therefore, it is possible to increase the amplitude and the resonance of the magnetic head 33.

Here, the piezoelectric plates 311, 312, 321
As a material of a, 322a, 321b, 322b, for example, a ceramic material such as barium titanate or lead zirconate titanate is used. Further, a polymer material such as poly-vinylidene fluoride can also be used. Intermediate electrode 3
As a material of 13, 323a and 323b, a metal material such as titanium alloy or stainless steel which is lightweight and has a small expansion coefficient is used.

Surface electrodes 314, 315, 324a, 32
The material of 5a, 324b, 325b is the piezoelectric plate 31.
1, 312, 321a, 322a, 321b, 322b
It is preferable that it has a coefficient of linear expansion close to or close to that of the above, good conductivity and oxidation resistance, and easy soldering. For example, a metal material such as nickel, silver, lead, molybdenum, tin, or the like. Alloy materials are used. Surface electrode 3
14, 315, 324a, 325a, 324b, 325
As a method of forming b, the piezoelectric plates 311, 312, 3
21a, 322a, 321b, 322b is formed by applying a paste of the above-mentioned material on the surface of 21a, 322a, 321b, 322b by screen printing and drying or baking, or by forming by metal spraying, vacuum deposition, sputtering, electroless plating or the like. is there.

The material of the leaf springs 35, 36 is not particularly limited as long as it is an elastic material, but for example, a metal plate such as copper, aluminum, silver or the like, a metal foil or a resin containing glass fiber, carbon fiber or the like is used. Manufactured by cutting or injection molding. As a material for the base holder 341 and the pressing holder 342, aluminum, brass, or a resin containing glass fiber, carbon fiber, or the like is used, and is manufactured by die casting, cutting, injection molding, or the like.

FIG. 3 is a plan view showing an example of a rotary drum of a rotary magnetic head device provided with the DT head device shown in FIG. 1 or 2. The DT head devices 30 and 40 are
The base holder 341 of the holder 34 is arranged so that the magnetic head 33 is swingably arranged on the circumference of the rotary drum 50.
An insulating plate is sandwiched between the rotary drum 50 and the rotary drum 50, and is supported and fixed on the rotary drum 50 by bolts. Holder 34
A drive circuit 51 for driving the bimorph 31 and the auxiliary bimorphs 32a, 32b, a detection circuit 52 for detecting the amount of bending displacement of the bimorph 31 and the auxiliary bimorphs 32a, 32b, and a recording / playback signal are amplified on the rotating drum 50 on the side of the. Printed circuit board 54 on which amplifier circuit 53 for mounting is mounted
Has been fixed.

Bimorph 31 and auxiliary bimorph 32
a, 32b surface electrodes 314, 315, 324a, 32
5a, 324b, 325b indirectly through the base holder 341, and the intermediate electrodes 313, 323a, 323b.
Are directly connected to the drive circuit 51. A strain gauge 3 attached to the center of the bimorph 31 and having a resistance value that changes according to the amount of bending displacement of the bimorph 31, for example.
7 is connected to the detection circuit 52. The magnetic head 33 is connected to the amplifier circuit 53.

The DT head devices 30 and 4 having the above structure
According to 0, the bimorph 31 is driven by the driving circuit 51.
By bending the auxiliary bimorphs 32a, 32b in the same direction at the same time, the bimorphs 31, 36 are arranged by the action of the leaf springs 35, 36 arranged in parallel and having both ends joined.
The entire curved shape of the auxiliary bimorphs 32a, 32b and the leaf springs 35, 36 is S-shaped. Therefore, the magnetic head 3
Since 3 moves parallel to the rotation axis direction of the rotary drum 50, it is possible to follow the recording track of the magnetic tape 55 that is obliquely wound around the outer peripheral surface of the rotary drum 50 during variable speed reproduction.

[0029]

As described above, according to the present invention,
Since only one set of members including electromechanical conversion elements is required, manufacturing cost and assembly cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an embodiment of a DT head device to which an embodiment of an actuator of the present invention is applied.

FIG. 2 is a schematic perspective view showing another embodiment of a DT head device to which the embodiment of the actuator of the present invention is applied.

FIG. 3 is a plan view showing an example of a rotary drum of a rotary magnetic head device including the DT head device shown in FIG. 1 or FIG.

FIG. 4 is a DT to which an example of a conventional actuator is applied.
FIG. 3 is a schematic perspective view showing an example of a head device.

FIG. 5 is a schematic perspective view showing an example of a rotary drum equipped with a DT head device to which another example of a conventional actuator is applied.

[Explanation of symbols]

30, 40 DT head device 31 Bimorph 32a, 32b Auxiliary bimorph 33 Magnetic head 34 Holder 35, 36 Leaf spring 37 Strain gauge 311, 321a, 322a, 321b, 322b Piezoelectric plate 313, 323a, 323b Intermediate electrode 314, 315, 324a, 325a, 324b, 32
5b Surface electrode 316 Chip base 341 Base holder 342 Holding holder 50 Rotating drum 51 Drive circuit 52 Detection circuit 53 Amplification circuit 54 Printed circuit board 55 Magnetic tape

Claims (4)

[Claims] 1. A first member formed of an electromechanical conversion element, a second member formed of an electromechanical conversion element arranged so as to sandwich one end of the first member, and a third member formed of an elastic material. Member, first holding means for connecting and holding one end of each of the second and third members, and second holding for connecting and holding each other end of the first and third members. And a means for bending the first, second and third members with the first holding means as a fixed fulcrum, and swinging the second holding means. 2. The actuator according to claim 1, wherein the third member is coupled to the second member with the first holding means interposed therebetween. 3. The actuator according to claim 1, wherein the third member is sandwiched and coupled between the second member and the first holding means. 4. A first member made of an electromechanical conversion element, a second member made of an electromechanical conversion element arranged so as to sandwich one end of the first member, and a third member made of an elastic material. Member, first holding means for connecting and holding one end of each of the second and third members, and second holding for connecting and holding each other end of the first and third members. Means, and a magnetic head fixed to the second holding means, the first holding means is used as a fixed fulcrum to bend the first, second and third members, and the second holding means is provided. A magnetic head device characterized in that the magnetic head is swung together with the means.