JPH11126318A - Actuator and magnetic head device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator which improves the wiring workability of extremely thin wires drawn out of the coil of a magnetic head and prevent disconnection when a magnetic head, etc., are mounted on the actuator formed by using a piezoelectric bimorph. SOLUTION: The piezoelectric bimorph 1 which is a first supporting body and a thin sheet 3 which is a second supporting body are fixed to a fixing member 2. the piezoelectric bimorph 1 and the thin sheet 3 are connected by a connecting member 4 on the opposite side of the fixing member 2. A flexible substrate 5 provided with circuits for transmitting signals is disposed along the thin sheet 3. The flexible substrate 5 and the thin sheet 3 are fixed in the prescribed range from the connecting member 4 side and the other end thereof is fixed to the prescribed section of the fixed member 2. The section of the connecting member 5 connected to the piezoelectric bimorph 1 comprises an easily curving flexible part 4a and curves in a direction reverse from the curving direction of the piezoelectric bimorph 1, thereby maintaining the attitude of the connecting member 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an actuator, and more particularly, to an actuator suitable for use in a magnetic head device mounted on a rotating drum such as a video tape recorder.

[0002]

2. Description of the Related Art A conventional actuator will be described with reference to FIGS. FIG. 6 is a schematic perspective view of a DT head device to which a conventional actuator is applied, and FIG. 7 is a cross-sectional view of the actuator showing the function of a tilt suppressing mechanism using a piezoelectric bimorph and a thin plate.

A so-called DT, in which a magnetic head slides to follow a recording track in order to obtain a high-quality image with little noise during special reproduction such as slow reproduction, reverse reproduction, and still image reproduction of a video tape recorder (VTR). (Dynamic
Tracking) head devices. As the actuator for performing the sliding operation of the magnetic head in the DT head device, a device having a bimorph cantilever structure composed of a piezoelectric element, which is an electromechanical conversion element, is frequently used.

FIG. 6 shows a DT head device 30 as an example to which such an actuator is applied. A piezoelectric bimorph 1 is generally provided on both surfaces of an intermediate electrode 1c made of a thin plate made of a material which does not easily expand and contract. The piezoelectric plates 1a and 1b made of thin plates are bonded together.

The intermediate electrode 1c is made of, for example, highly rigid phosphor bronze, a composite material containing carbon fiber, or a highly rigid plastic material. Also, the piezoelectric plate 1
a and 1b are made of, for example, ceramics and plastics having piezoelectricity, and surface electrodes 1d and 1e are formed on both sides of the piezoelectric plates 1a and 1b by plating, vapor deposition, baking, and the like, respectively. Polarization is performed in the direction. Thus, when a predetermined voltage is applied to this actuator, one of the piezoelectric plates expands and the other contracts, so that a deformation occurs such that the piezoelectric plate is displaced in a direction indicated by an arrow x in FIG.

Further, one end of the piezoelectric bimorph 1 is sandwiched and fixed by a fixing member 2a and a fixing member 2b, and one or both of the fixing members 2a and 2b are fixed to a predetermined position with respect to the rotating drum. It is fixed to the position by screws or the like.

A head base 8 to which a magnetic head 9 is attached is fixed to the other end of the piezoelectric bimorph 1. Further, the thin plate 3 is fixed to the head base 8 in parallel with the piezoelectric bimorph 1. This thin plate 3
For example, a material such as a highly rigid phosphor bronze, a composite material containing carbon fiber, or a highly rigid plastic material is used. One end of the thin plate 3 is sandwiched and fixed between the fixing members 2b and 2c.

The thin plate 3 acts to prevent the magnetic head 9 from tilting when the piezoelectric bimorph 1 is curved as shown in FIG. 7 and the magnetic head 9 is vertically displaced. That is, when the piezoelectric bimorph 1 is deformed, the tip of the piezoelectric bimorph 1 is inclined according to the deformation. However, if there is a thin plate 3, this thin plate 3
And the head base 8
The flexible portion 8a is curved in a direction opposite to that of the piezoelectric bimorph 1, so that the angle at which the magnetic head 9 contacts the magnetic tape 13 is always kept constant, and good reproduction is possible.

On the other hand, the magnetic head 9 is wound with an ultrafine wire made of copper as a conductor and having an insulating film of polyurethane, polyester or the like on its outer periphery, thereby forming a coil 10 for magnetic detection. The terminal end of the coil is guided to the fixing member 2c of the DT head device 30, and is fixed to the land 12 by solder or the like.

[0010]

However, as described above, the wire used for the coil is extremely thin (for example, the outer diameter is about several tens of μm), while the size of the actuator is, for example, L4 shown in FIG. About 50 mm is common. Therefore, an extra fine wire is to be wired beyond this length, but a trouble such as disconnection is likely to occur during the work, and the workability and the reliability are poor.

Further, the magnetic head device is a movable head, and there is a possibility that the wire rod may be broken by repetitive operations. The frequency of the normal repetitive operation is about several tens Hz to several hundreds Hz, and the amplitude of the tip of the magnetic head is 1 m.
m in some cases, and disconnection was likely to occur depending on the place and method of wiring.

For these measures, in the wiring from the magnetic head coil to the fixing member, wiring should be performed at a portion where distortion is hardly generated during the vibration, and an adhesive for fixing the wire and an adhesive for reinforcing the wiring should be selected. In addition, work is performed so that stress is not applied to the wire at the time of wiring, but it has been difficult to reduce the work time and to suppress the disconnection failure.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the workability of wiring an extra-fine wire for transmitting an electric signal drawn from a coil of a magnetic head when a magnetic head or the like is mounted on the actuator in an actuator using a piezoelectric bimorph. It is another object of the present invention to provide an actuator that prevents disconnection due to repeated vibration.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and according to the first aspect of the present invention, in an actuator for moving an object to be controlled in one axial direction, a base member is provided. And a piezoelectric bimorph constituting a first support, a thin plate constituting a second support, which is erected on the base member in parallel with the piezoelectric bimorph, and on a side opposite to the base member, To connect the piezoelectric bimorph and the thin plate, a connecting member having a flexible portion at a connection portion with the piezoelectric bimorph, and to transmit an electric signal from the connecting member to the base member along the thin plate along the thin plate. And a flexible substrate provided, wherein the flexible substrate is fixed in a predetermined range in the direction of the base member from a portion of the thin plate coupled to the connecting member, Et al, the other end of the flexible substrate is an actuator which is secured to a predetermined position of the base member.

According to a second aspect of the present invention, the range of the flexible substrate according to the first aspect of the present invention, which is fixed to the thin plate, is at least １ ／ or more of the length of the movable portion of the thin plate. I do.

According to the third aspect of the invention, the portion of the flexible substrate according to the first aspect that is not fixed to the thin plate has a Y-shape that opens toward the base member. It shall be.

Further, according to the invention described in claim 4,
A magnetic head device using the actuator according to claim 1 is configured to solve the above problem.

When the actuator of the present invention is applied to, for example, a magnetic head device, a very thin wire drawn from a coil of a magnetic head portion for transmitting and receiving signals is connected to a wiring pattern provided on a flexible member. Because of the structure, the efficiency of the manufacturing work of the magnetic head device is improved,
The possibility of coil breakage during use is reduced, and the reliability of the magnetic head device is improved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view showing the structure of the actuator of the present invention, and FIG. 2 is a schematic perspective view of a DT head device to which the actuator of the present invention is applied. FIG. 3 is a view showing A- of the DT head device shown in FIG.
It is A sectional side view. FIG. 4 shows an example of a wiring pattern of a flexible member used in the DT head device shown in FIG. 2, for example, a flexible printed board (hereinafter, referred to as a "VH flexible board"). It is a figure showing a shape.

The present invention relates to an actuator for controlling the position of a magnetic head or the like. The structure of the actuator is as shown in FIG. The piezoelectric bimorph 1 and the thin plate 3 are connected by a connecting member 4 on the side opposite to the fixing member 2. Further, a flexible substrate 5 provided with a circuit for transmitting a signal is provided along the thin plate 3. The flexible substrate 5 is fixed to the thin plate 3 in a predetermined range from the connecting member 4 side, and the other end is fixed to a predetermined portion of the fixing member 2.

The portion of the connecting member 4 which is connected to the piezoelectric bimorph 1 is constituted by a flexible portion 4a which easily bends. When a voltage is applied to the piezoelectric bimorph 1, the portion is bent and the position of the connecting member 4 moves. When this is done, the flexible portion 4a bends in the direction opposite to the bending direction of the piezoelectric bimorph 1, and the posture of the connecting member 4 is maintained.

The provision of the flexible substrate 5 is a feature of the present invention. For example, a magnetic head fixed to the connecting member 4 via a circuit provided on the flexible substrate 5 Can be extracted to the outside, and handling of extremely thin wires can be reduced, which greatly contributes to improvement in workability and reliability.

Next, an embodiment in which the present invention is applied to a magnetic head device will be described. Although the embodiments described below are preferred specific examples of the present invention, various technically preferable limitations are added thereto. However, the scope of the present invention is particularly limited in the following description. It is not limited to these forms unless otherwise described.

As shown in FIG. 2, the DT to which the present invention is applied
The head device 20 has a trapezoidal piezoelectric bimorph 1.
And a fixing member 2a having a screw hole for fixing the piezoelectric bimorph 1 and fixing the piezoelectric bimorph 1 to a drum; a fixing member 2b and a fixing member 2c for sandwiching the piezoelectric bimorph 1 and the thin plate 3; VH flexible substrate 5a,
The piezoelectric bimorph 1 includes a head base 8 for fixing a magnetic head 9 to the tip of the piezoelectric bimorph 1, and a coil 10 formed on the magnetic head 9.

The piezoelectric bimorph 1 has two piezoelectric plates 1a, 1
b are bonded together with the intermediate electrode 1c interposed therebetween, and the surface electrodes 1d and 1e are formed on the bonded both surfaces. Here, as the material of the piezoelectric plates 1a and 1b, for example, a ceramic material such as barium titanate or lead zirconate is used. Alternatively, a polymer material such as polyvinylidene fluoride can be used.

As the material of the intermediate electrode 1c, for example, a titanium alloy, stainless steel, a carbon fiber resin material in which carbon fiber and resin are mixed at a predetermined ratio, and the like are used.

The material of the surface electrodes 1d and 1e has a coefficient which is equal to or close to the coefficient of linear expansion of the piezoelectric plates 1a and 1b, has good conductivity and oxidation resistance, and is easy to solder. Are preferable, for example, nickel, gold,
A metal material such as silver, molybdenum, or tin, or an alloy material thereof is used.

As a method of forming the surface electrodes 1d and 1e, a paste of the above-mentioned material is applied to the surfaces of the piezoelectric plates 1a and 1b by a printing method or the like and dried or baked, or metal spraying or vacuum evaporation , Sputtering, electroless plating and the like can be used.

As the material of the fixing member 2a, a conductive material such as aluminum or brass, or a material in which a conductive material is formed on the surface of an insulating material by plating or the like is used. Examples of the material of the fixing members 2b and 2c include a conductive material such as aluminum and brass, and a piezoelectric plate 1a made of an insulating material.
A conductive material formed by plating or the like only on the surface sandwiching 1b is used. Further, on one surface of the fixing member 2c, for example, a flexible printed board, a printed board, or the like is provided for transmitting a magnetic signal, a driving signal for a piezoelectric bimorph, and the like.

The materials of the thin plate 3 and the head base 8 are as follows.
For example, a resin having a high specific rigidity, such as titanium or a carbon fiber-containing resin, is used. Further, it is preferable that the material characteristics be close to the linear expansion coefficient of the piezoelectric bimorph. Therefore, it is common to use the material used for the intermediate electrode 1c of the piezoelectric bimorph 1.

The head base 8 has a bonding portion 8a for bonding to the piezoelectric bimorph 1 and a flexible portion 8 which bends in a direction opposite to the bending of the tip of the piezoelectric bimorph 1 to cancel the bending.
b, and a mounting portion 8c to which the magnetic head 9 is mounted.

The thickness of the head base 8 and the fixing member 2b is adjusted so that the thin plate 3 becomes parallel to the piezoelectric bimorph 1, and the bonding portion 3a is formed with the head base 8 at a predetermined overlapping width.
Adhesively fixed.

A predetermined number of magnetic heads 9 are fixed on a head base 8, and the magnetic head 9 is provided with a coil 1 made of a fine wire.
0 is formed. The coil 10 has an insulating film of polyurethane, polyester or the like on the outer periphery, and has a diameter of 30 μm to 50 μm.
It is an ultra-fine wire using copper of μm as a conductor, and the outer diameter of the wire is about 40 μm to 80 μm.

The terminal of the above-described coil 10 passes through the side surface of the head base 8, and is bonded to the bonding portion 3 of the head base 8 and the thin plate 3.
a and is soldered to the land of the VH flexible substrate 5a bonded to the bonding portion 3a.

As the material of the VH flexible substrate 5a, for example, a single-sided flexible material using polyimide and rolled copper foil is used. Regarding the shape of the VH flexible substrate 5a, the portion fixed to the movable portion is made as light as possible to prevent the deterioration of the characteristics of the DT head due to the weight of the flexible material, for example, the deterioration of the tip displacement amount per applied voltage and the response frequency characteristics. It is constituted so that it may become.

FIG. 3 shows A of the DT head device 20 shown in FIG.
FIG. 4 is a cross-sectional view taken along line A, where L1 is the length of the movable portion of the thin plate 3, L2 is the length of the VH flexible substrate 5a fixed to the thin plate 3, and L3 is the VH flexible substrate 5a. Is the length of the free part. These L1 to L3 have a preferable relationship for obtaining the effect of the present invention, as described later.

The wiring pattern of the VH flexible substrate 5a is formed such that the impedance of the pattern portion is as small as possible. The pattern width is, for example, 0.2 mm or less, and the pattern interval is, for example, 0.2 mm
Less than or equal. In the case where two magnetic heads 9 are mounted on the head base 8, it is desirable to separate the respective patterns as shown in FIG. 4, and it is desirable that W1 <W2 in the same figure.

The VH flexible board 5a is soldered from the thin plate 3 to a land 12 incorporated on the fixing member 2c. 5 (a) to 5 (c) are portions which are not fixed to the thin plate 3 and can be formed in various shapes as shown in FIG. It can be formed into a shape that obtains a predetermined flexibility between them. Therefore,
As the shape of the VH flexible substrate 5a, in addition to the above-described shape in FIG. 4A, a Y-shape in FIG. 4B and an L-shape in FIG.

The VH flexible substrate 5a and the thin plate 3 can be fixed to each other by, for example, bonding with an adhesive sheet or the like provided on the back surface of the VH flexible substrate 5a.
At this time, if the length of bonding between the VH flexible substrate 5a and the thin plate 3, that is, L2 shown in FIG.
VH flexible substrate 5a hits thin plate 3 when vibrates,
The vibration state of the tip of the magnetic head 9 is not stable.

Therefore, as a result of various studies on the length to be bonded, the bonding length L2 is set to be at least で or more of the length L1 of the movable portion of the thin plate 3. Has been obtained, and is preferably set to this value.

The above-mentioned VH flexible substrate 5a may be formed integrally with a flexible substrate for inputting and outputting signals from the DT head device 20.

In the above-described embodiment, the driving body is configured as a bimorph element in which a piezoelectric plate is bonded. However, the present invention is not limited to this. For example, the driving body may be configured using a stacked-type piezoelectric bimorph element. .

In the above-described embodiment, the magnetic head is adhered to the tip. However, the present invention is not limited to this, and it is needless to say that the present invention can be applied to a structure in which an element that needs to transfer signals is movable. It is.

Further, in the above-described embodiment, the shape of the VH flexible substrate is shown as T-shape, Y-shape, and L-shape. However, the VH-flexible board has the same function as the VH flexible board according to the present invention. It is natural that you can do it.

[0045]

As is apparent from the above description, according to the actuator of the present invention, a flexible material having excellent durability is provided in a region where repetitive bending or a movable portion where repetitive expansion and contraction occurs, instead of a fine wire. Can be wired. Therefore, the wiring work can be facilitated and the quality can be improved. For example, by using this actuator for a DT head device, a high-quality and low-cost device can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an actuator of the present invention.

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

FIG. 3 is a cross-sectional side view of the DT head device shown in FIG.

FIG. 4 is an example of a wiring pattern of a VH flexible substrate used in the DT head device shown in FIG.

FIG. 5 is a view showing a shape of a VH flexible substrate.

FIG. 6 is a schematic perspective view of a DT head device to which a conventional actuator is applied.

FIG. 7 is a cross-sectional view of an actuator showing a function of a tilt suppressing mechanism using a piezoelectric bimorph and a thin plate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1: Piezoelectric bimorph, 1a, 1b: Piezoelectric plate, 1c: Intermediate electrode, 1d, 1e: Surface electrode, 2, 2a, 2b, 2c ...
Fixing member, 3 ... thin plate, 3a ... adhesive portion, 4 ... connecting member, 4
a: flexible portion, 5: flexible substrate, 5a: VH flexible substrate, 8: head base, 8a: adhesive portion, 8b: flexible portion, 8c: mounting portion, 9: magnetic head, 10: coil , 1
2 land, 13 magnetic tape, 14 free part

Claims (4)

[Claims] 1. An actuator for moving an object to be controlled in one axial direction, comprising: a piezoelectric bimorph that is erected on a base member and forms a first support; and is erected on the base member in parallel with the piezoelectric bimorph.
A thin plate that constitutes a second support, and a connecting member that connects the piezoelectric bimorph and the thin plate on a side opposite to the base member and has a flexible portion at a connection portion with the piezoelectric bimorph, Along with the thin plate, a flexible substrate provided for transmitting an electric signal from the connecting member to the base member, wherein the flexible substrate is connected to the connecting member of the thin plate. An actuator, wherein the actuator is fixed in a predetermined range from the joined portion in the direction of the base member, and the other end of the flexible substrate is fixed to a predetermined position of the base member. 2. The actuator according to claim 1, wherein a range in which the flexible substrate is fixed to the thin plate is at least の or more of a length of a movable portion of the thin plate. 3. The actuator according to claim 1, wherein the shape of the portion of the flexible substrate that does not adhere to the thin plate is a Y-shape that opens toward the base member. 4. A magnetic head device using the actuator according to claim 1.