JP3834483B2 - Magnetic disk drive and head support mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic disk device and a head support mechanism for a magnetic disk device, and in particular, for accurately positioning a head for writing and reading information at a predetermined position on a magnetic disk in which information is stored. It relates to the coating of the actuator.
[0002]
[Prior art]
Conventionally, a voice coil motor has been used as an actuator for moving a magnetic head to a desired position on a disk. However, this method has a limit in improving positioning accuracy. Therefore, as a method for performing a positioning operation with higher accuracy, a configuration in which a second actuator for finely adjusting the position of the magnetic head is arranged between the voice coil motor and the magnetic head has been proposed.
[0003]
For example, the structure of the second actuator described in JP-A-12-1113615 includes a magnetic head for writing and reading information, a magnetic disk for storing information, an elastic member for supporting the head, A fixing member that supports the elastic member, a first actuator for coarse movement for moving the magnetic head to a predetermined position on a magnetic disk, and the first actuator and the magnetic head are disposed between the first actuator and the magnetic head. In the magnetic disk device having the second actuator for fine movement, the second actuator includes one or a plurality of stacked piezoelectric elements having electrodes on the upper surface and the lower surface and having two or more polarization regions inside. 2nd actuator which is the plate-shaped structure comprised from a property flat plate, and the upper surfaces or lower surfaces of the said fixing member and the said elastic member are the said plate-shaped structures. In which were arranged so as to bridge with an upper surface or lower surface of the.
[0004]
Further, the second actuator is a plate-like structure composed of a single or laminated piezoelectric flat plate made of a piezoelectric material and having electrodes on the upper surface and the lower surface, The electrode on at least one of the electrodes on the lower surface is separated into two or more, and the piezoelectric flat plate is separated by an unpolarized region and a part of the unpolarized region. Two or more polarization regions polarized in the thickness direction of the piezoelectric flat plate, and the electrodes on the upper and lower surfaces of the piezoelectric flat plate are provided in two or more polarization regions in the piezoelectric flat plate. The piezoelectric flat plate is displaced in the in-plane direction of the piezoelectric flat plate by applying an electric field in the thickness direction of the piezoelectric flat plate.
[0005]
[Problems to be solved by the invention]
The second actuator in the above-described prior art is made of ceramics such as PZT, which is a piezoelectric element, so that it is brittle and has a problem in mechanical strength. Further, this actuator is metallized with Au or the like for attaching an electrode, and when a device is expanded and contracted by applying a voltage, fine particles of PZT and Au are generated. Then, there is a problem that the particles adhere to the magnetic head or the disk or the inside of the apparatus is contaminated, causing a decrease in reliability at the time of writing and reading information.
[0006]
[Means for Solving the Problems]
In order to improve the above problems, the present inventors have conducted an experimental study and found that the problem can be solved by the following means.
That is, in a magnetic disk device having a second actuator made of a piezoelectric element, the surface of the second actuator is coated with a liquid adhesive and cured and resin-coated, so that the element at the time of applying a voltage expands and contracts. It has been found that fine particles of PZT or metallized Au, which are materials of the actuator, can be prevented from dusting.
[0007]
Hereinafter, the present invention will be described in detail.
The liquid adhesive used for resin coating is preferably a low-viscosity resin having a viscosity before curing of the resin of 1000 mPas or less because it is uniformly applied with a film thickness of 10 micrometers or less by means such as a dispenser or inkjet. The application resin can be a photo-curing (UV, visible light) type, but in the case of thermosetting, it is necessary that the resin be cured at a temperature lower than the heat resistance temperature of the piezoelectric element. In the case of a type that cures at a temperature lower than the heat resistance temperature of the piezoelectric element, a combination type of heat and light curing is also possible.
[0008]
In addition, when volatile organic molecules are generated as outgas from the resin after curing, the coating resin adheres to the magnetic head or the disk or contaminates the inside of the device, resulting in a decrease in reliability during information writing and reading. Because of this, the adhesive must have a low resin outgas after curing. In addition, the adhesive strength to the metallized Au is high, and the cured resin is flexible, low elastic modulus, high elongation rate, so as not to cause cracks and the like during expansion and contraction of the piezoelectric element to which voltage is applied, Must be a low hardness adhesive.
[0009]
As a result of studying a resin satisfying such characteristics, the present inventors have found that a low-viscosity epoxy resin adhesive is optimal. The low-viscosity epoxy resin adhesive is composed of an epoxy oligomer having a content of less than 20% and an epoxy monomer having a content of 80% or more, and includes at least a polymerization initiator, a catalyst, and an additive that react with heat or light. is there.
The polymerization initiator and catalyst that react with heat or light can be any of amine, acid anhydride, and cation. Additives can be added within a range that does not adversely affect adhesiveness and other properties, and are surfactants for improving the wettability of the adherend and fillers for improving the physical properties of the cured product. Etc.
[0010]
Examples of such low-viscosity epoxy resin adhesives include World Rock XOC-11CKF-3 and XOC-11CKF-3H manufactured by Kyoritsu Chemical Industry. However, it is not limited to these, and an epoxy oligomer having a content of less than 20%, an epoxy monomer having a content of 80% or more, and a polymerization initiator, catalyst, and additive that react with heat or light are appropriately adjusted. Also good.
[0011]
On the other hand, an adhesive other than the low-viscosity epoxy resin adhesive is not suitable as the resin of the present invention. For example, since a general low viscosity coating agent contains a solvent or is an acrylic resin, a large amount of outgas is generated from the resin after curing, which is not preferable.
In addition, a general epoxy resin has a high content of epoxy oligomer, a high viscosity, and it is difficult to apply uniformly with a film thickness of 10 micrometers or less. In addition, since the cured resin is not flexible and is hard, it is not preferable because a voltage is applied to cause cracks or the like when the piezoelectric element expands or contracts, causing dust generation.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a top view showing the structure of a magnetic disk apparatus according to an embodiment of the present invention. In the present embodiment, a magnetic recording disk 310 that stores information on a magnetic film formed on the surface thereof and a spindle motor 300 for rotating the magnetic recording disk 310 are provided. Furthermore, a magnetic head (not shown) including an electromagnetic transducer for reading and writing information on the magnetic recording disk 310 is provided, and a slider (not shown) for floating on the magnetic disk at a predetermined interval. It has.
[0013]
The slider is provided on a gimbal 210 that passively corrects the attitude relative to the magnetic disk. The gimbal 210 is connected to one end of a suspension 200 that is an elastic member that elastically supports the magnetic head and the slider. The other end of the suspension 200 is connected to a suspension support member 230 that is a fixed member. The suspension support member 230 is provided with a first actuator for moving the magnetic head to a predetermined position on the magnetic disk for rough positioning.
[0014]
The first actuator includes a voice coil motor 250, a magnet 251 constituting the voice coil motor, a coil 252, a suspension support member rotating shaft 241 serving as a rotation center when the magnetic head is positioned by the voice coil motor, It consists of a bearing 240. Further, a second actuator 100 for fine movement is provided between the voice coil motor and the magnetic head in order to position with high accuracy, and the surface is coated with a coating resin 101.
[0015]
FIG. 2A is a top view showing in more detail the entire magnetic head support mechanism from the suspension support member 230 to the magnetic head according to the embodiment of the present invention. FIG. 2B is a cross-sectional view showing a cross section A of the entire magnetic head support mechanism shown in FIG. The second actuator 100 is a plate-like structure in which piezoelectric flat plates described later are laminated.
In the present embodiment, the lower surface of the second actuator 100 is used to bridge the upper surfaces of the suspension support member 230 and the suspension 200. The lower surface of the second actuator 100 and the upper surface of the suspension 200 are fixed with an adhesive layer 501. Similarly, the lower surface of the second actuator 100 and the upper surface of the suspension support member 230 are fixed by an adhesive layer 502.
[0016]
In this embodiment, the above-described adhesion uses an epoxy adhesive. Here, the side on which the slider 220 is fixed with respect to the suspension 200 is defined as the lower surface, and the opposite side is defined as the upper surface. Connection electrodes 111 and 112 for supplying electric power to the second actuator are formed on the lower surface of the second actuator 100, and lead electrodes 261 and 262 formed on the upper surface of the suspension support member 230 and solder are used. Electrically connected. The connection by solder also contributes to the mechanical connection between the second actuator and the suspension holding arm.
[0017]
Further, the surface of the second actuator 100 is coated with a coating resin 101. The coating resin is uniformly applied with a low-viscosity epoxy resin adhesive with a film thickness of 10 micrometers or less by a dispenser, ink-jet method, etc., and heated with light irradiation (UV, visible light), oven oven, hot plate, etc. To harden and form. It is also possible to use a combination of heat and light curing.
[0018]
FIG. 3A is a top view showing a detailed structure of the second actuator 100 used in this embodiment. FIG. 3B is a cross-sectional view showing a B cross section of the second actuator shown in FIG.
The second actuator of the present embodiment is a piezoelectric flat plate 105 having a plate-like structure formed of a material having piezoelectricity. The piezoelectric flat plate 105 includes two electrodes 118a and 118b on the upper surface and two electrodes 118c and 118d on the lower surface. Here, in the thickness direction of the piezoelectric flat plate, the left side in FIG. 3B is the upper surface side and the right side is the lower surface side. The piezoelectric flat plate 105 has a polarized region 601 in a region sandwiched between the electrodes 118a and 118c, and a polarized region 602 in a region sandwiched between the electrodes 118b and 118d. That is, it has two polarization regions in one piezoelectric flat plate. As described above, the second actuator of this example is a plate-like structure including the piezoelectric flat plate 105 having electrodes on the upper surface and the lower surface and having two polarization regions inside.
[0019]
Next, the operation of the second actuator in this embodiment will be described.
FIG. 4 is a cross-sectional view showing an example of the direction of polarization in the piezoelectric flat plate constituting the second actuator and the state of the electric field when driving the actuator. The polarization directions of the two polarization regions of the piezoelectric flat plate 105 are in the thickness direction of the piezoelectric flat plate and opposite to each other. An electric field is applied to the piezoelectric flat plate in such a polarization state as shown in FIG. That is, an electric field is applied to the polarization region 601 so that the polarization direction and the electric field direction are the same, and an electric field is applied to the polarization region 602 so that the polarization direction and the electric field direction are opposite to each other. To do.
[0020]
FIG. 5A is a top view showing a state of displacement in the plane (positioning direction) of the second actuator 100 when such an electric field is applied. FIG. 5B is a C cross-sectional view showing the displacement of the second actuator shown in FIG. 5A in the thickness direction (perpendicular to the upper surface of the actuator). The polarization region 601 is displaced so as to shrink in the in-plane direction and to extend in the thickness direction because the polarization direction and the electric field direction are the same. On the other hand, the polarization region 602 is displaced so as to extend in the in-plane direction and to contract in the thickness direction because the polarization direction and the electric field direction are opposite.
[0021]
Therefore, by applying the electric field described above to the second actuator, the suspension 200 fixed to the second actuator 100 can be displaced in the plane (in the positioning direction) with respect to the suspension support member 230. By changing the strength and direction of the applied electric field, the magnetic head fixed to the tip of the suspension 200 can be finely moved in the positioning direction with high accuracy. At this time, the second actuator 100 is also displaced in the thickness direction of the actuator as shown in FIG.
[0022]
Since the magnetic disk device of the present embodiment only needs to fix the second actuator between the suspension and the suspension support member, the magnetic disk device can be a highly productive magnetic disk device, not only highly reliable, A magnetic disk device in which reading and writing of the magnetic head are stable can be achieved.
[0023]
In this embodiment, the thickness of the piezoelectric flat plate per layer can be reduced by laminating the piezoelectric flat plates, so that the strength of the electric field applied to the piezoelectric flat plate (the voltage applied to the second actuator / The thickness of the piezoelectric flat plate can be increased. Since the displacement of the second actuator is proportional to the strength of the electric field, a large displacement can be obtained with a low voltage.
Furthermore, since the second actuator is resin-coated, it is possible to prevent fine particles of PZT, which is a material of the actuator, or metallized Au from being generated when the element is expanded or contracted when a voltage is applied. When dust generation was actually measured with a particle counter, particles of 1 micrometer or more were not detected in the apparatus, and no information writing / reading error occurred.
[0024]
The cured film of the resin coated by the method described in this example is a uniform film of 5 micrometers or less. The cured film has an elastic modulus of 700 MPa, an elongation of 50%, and a Shore D The hardness is 70 and it is flexible. Therefore, no crack was generated even when the piezoelectric element was expanded and contracted 10 billion times by applying a 5 V voltage.
[0025]
On the other hand, when the cured resin was analyzed by GC-MS, outgas (volatile organic molecules) was detected at 0.005 micrograms per milligram of resin, but the outgas amount was low and information writing / reading errors were detected. Did not occur.
In addition to the above-described embodiments, many methods for applying an electric field to two polarization regions in a piezoelectric flat plate are conceivable. If different electric fields are applied to the two polarization regions, the same in-plane displacement can be generated. Further, although there are two polarization regions in the piezoelectric flat plate, three or more polarization regions may be provided.
[0026]
In the above-described embodiment, the second actuator is disposed so as to bridge the upper surfaces of the suspension and the suspension support member, but may be disposed so as to bridge the lower surfaces.
In addition, one element, which is a piezoelectric flat plate, is fixed as the second actuator so as to bridge the upper surfaces of the suspension and the suspension support member. You may fix so that lower surfaces may bridge | crosslink. In this case, one element is fixed so as to bridge the upper surfaces of the suspension and the suspension support member, and the other element is fixed so as to bridge the lower surfaces of the suspension and the suspension support member.
[0027]
Furthermore, in the above-described embodiment, the second actuator is disposed between the suspension and the suspension support member. However, the second actuator may be disposed in the suspension support member or in the suspension.
The above embodiments are all related to a magnetic disk device, but may be used in a magnetic disk array device in which a plurality of magnetic disk devices are arranged, or a storage device using a rotational recording medium other than a magnetic disk, for example, Of course, it may be used for an optical disk device, a magneto-optical recording device, or the like.
[0028]
Next, another embodiment of the present invention will be described with reference to the drawings.
The resin coating of the second actuator described in the first embodiment is applied to the head support mechanism as shown in FIG. 3 on page 691 of the Journal of the Institute of Electrical Engineers of Japan, Vol. 120, No. 11 (November 2000) (FIG. 6). Applied to. That is, the magnetic head support mechanism (FIG. 6) having a structure in which the suspension 200 and the suspension support member 210 are connected by two horizontally disposed elements 100a and 100b and a φ-type hinge 700 and the above-described magnetic head support mechanism were used. Even when used in a magnetic disk device and a storage device using a rotational recording medium other than the magnetic disk, the same effects as those of the first embodiment described above can be obtained.
[0029]
In this case, the resin coating is performed by electrically and mechanically connecting the two elements 100a and 100b to the suspension 200 and the suspension support member 210, and then applying the resin coating. At that time, there is a slight possibility that the gap 800 between the φ-type hinge 700 and the two elements 100a and 100b is filled with resin. However, even if the gap is filled with resin, the displacement of the head that can be generated by the second actuator 100, that is, the two elements 100a and 100b, is not affected.
[0030]
As a result of the experiment, the displacement when the gap is filled with the resin (elastic modulus 700 MPa after curing) used in the first example is the displacement amount 99.9 when the gap 800 is not filled with the resin. % Or more.
[0031]
Next, a comparative example for comparison with the above-described embodiment will be described.
As Comparative Example 1, 131 magnetic disk devices manufactured without resin coating by the method described in Japanese Patent Application Laid-Open No. 12-113615 are 131 particles when dust generation of 1 micrometer or more is measured with a particle counter. An information write / read error occurred.
[0032]
As Comparative Example 2, an attempt was made to perform resin coating 101 with an epoxy adhesive having a general viscosity of 10000 mPas by the method described in this example. However, the film thickness after application and curing was 10 micrometers or less. It was not a uniform film. The cured film had an elastic modulus of 2000 MPa, an elongation of 3%, a Shore D hardness of 90, and cracked when the piezoelectric element was expanded and contracted 10,000 times by applying a 5V voltage.
[0033]
As Comparative Example 3, when a resin coating was performed with a general acrylic adhesive having a viscosity of 8000 mPas by the method described in this example, volatile organic molecules were generated as outgas from the cured resin, and GC- When analyzed by MS, 1.1 microgram per milligram of resin was detected, and an information write / read error occurred.
[0034]
【The invention's effect】
According to the present invention, the actuator can be driven with a low voltage. In addition, since there is no displacement in the direction perpendicular to the upper surface of the actuator during driving, and no dust is generated, it is possible to provide a magnetic disk device with high magnetic head writing / reading reliability and high productivity. Thereby, it is possible to improve the recording density of the rotating disk type information storage device.
[Brief description of the drawings]
FIG. 1 is a top view showing a structure of a magnetic disk device according to an embodiment of the present invention.
FIGS. 2A and 2B are a top view and a cross-sectional view showing the entire magnetic head support mechanism used in the magnetic disk apparatus of the present invention. FIGS.
FIGS. 3A and 3B are a top view and a cross-sectional view showing a structure of a second actuator. FIGS.
FIG. 4 is a cross-sectional view showing a polarization region of a second actuator.
FIGS. 5A and 5B are a top view and a cross-sectional view showing a displacement of a second actuator. FIGS.
FIG. 6 is a perspective view showing an entire magnetic head support mechanism according to another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100, 100a, 100b ... 2nd actuator, 101 ... Coating resin, 111, 112 ... Connection electrode, 118a, 118b, 118c, 118d ... Electrode, 105 ... Piezoelectric flat plate, 200 ... Suspension, 210 ... Gimbal, 220 ... Slider, 230 ... Suspension support member, 240 ... Bearing, 241 ... Suspension support member rotating shaft, 250 ... Voice coil motor, 251 ... Permanent magnet, 252 ... Coil, 300 ... Spindle motor, 261, 262 ... Extraction electrode, 310 ... Magnetic Disc, 501, 502 ... Adhesive layer, 601, 602 ... Polarization region, 700 ... φ-type hinge, 800 ... Gap

Claims (6)

A magnetic head for writing and reading information, a magnetic disk for storing information, an elastic member for supporting the magnetic head, a fixing member for supporting the elastic member, and the magnetic head on the magnetic disk A first actuator for moving the first actuator to a predetermined position of the piezoelectric element , and a second actuator disposed between the first actuator and the magnetic head . A magnetic disk drive characterized in that a surface including an electrode is coated with an epoxy resin, and the elastic modulus of the epoxy resin after curing is 700 MPa or less . 2. The magnetic disk device according to claim 1, wherein the epoxy resin is obtained by curing a precursor containing an epoxy oligomer having a content of less than 20% and an epoxy monomer having a content of 80% or more . 2. The magnetic disk drive according to claim 1, wherein the Shore D hardness after curing of the epoxy resin is 70 or less . 2. The magnetic disk device according to claim 1, wherein the elongation percentage of the epoxy resin after curing is 50% or more . A magnetic head for writing and reading information; an elastic member for supporting the magnetic head; a fixing member for supporting the elastic member; and an actuator for positioning the magnetic head between the elastic member and the fixing member. A head support mechanism , wherein a surface including an electrode of a piezoelectric element constituting the actuator is coated with an epoxy resin, and an elastic modulus of the epoxy resin after curing is 700 MPa or less . The head support mechanism according to claim 5, wherein the epoxy resin is obtained by curing a precursor containing an epoxy oligomer having a content of less than 20% and an epoxy monomer having a content of 80% or more .

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