Abstract:
A vibration-canceling mechanism includes a vibration transfer member. At least part of the vibration transfer member is inserted between a vibration-origination system having at least one resonance frequency and an object to which a vibration is applied from the vibration-origination system. The vibration transfer member has a resonance frequency equal to or near the at least one resonance frequency of the vibration-origination system. One end section of the vibration transfer member is fixed to the vibration-origination system and the other end section of the vibration transfer member is fixed to the object so that an apparent vibration of the object is substantially canceled by a resonance of the vibration transfer

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a vibration-canceling mechanism for an object subjected to a mechanical vibration, and to a head gimbal assembly (HGA) with the vibration-canceling mechanism.  
         DESCRIPTION OF THE RELATED ART  
         [0002]    In a magnetic disk drive apparatus, thin-film magnetic head elements for writing magnetic information into and/or reading magnetic information from magnetic disks are in general formed on magnetic head sliders flying in operation above the rotating magnetic disks. The sliders are supported at top end sections of suspensions of HGAs, respectively.  
           [0003]    In operation, the HGA and therefore the magnetic head slider are driven or swung along a radial direction of the magnetic disk (track-width direction) by an actuator called as a voice coil motor (VCH), and thus a position of the magnetic head element with respect to a track in the magnetic disk is controlled.  
           [0004]    The actuator, a drive arm coupled to the actuator and a suspension have inherent resonance characteristics with resonance frequencies different from each other, respectively. Thus, to the magnetic head slider attached at the top end section of the suspension, a mechanical vibration modified by a composite characteristic of these inherent resonance characteristics will be transferred.  
           [0005]    In order to suppress such mechanical vibration modified by the composite resonance characteristic, conventionally, a resonance peak of an electrical drive signal was suppressed by at least one multi-stage filter mounted in a servo circuit of the actuator.  
           [0006]    However, because such electrical vibration-suppressing method needed to provide the multi-stage filter, the servo circuit was complicated in configuration and thus the manufacturing cost increased. Also, since the mechanical vibration was suppressed by the electrical means not directly by a mechanical means, efficiency for suppression was extremely low.  
         SUMMARY OF THE INVENTION  
         [0007]    It is therefore an aim of the present invention to provide a vibration-canceling mechanism and an HGA with the vibration canceling, whereby a mechanical vibration applied to an object can be suppressed with efficiency without greatly changing a conventional structure of the HGA.  
           [0008]    Another aim of the present invention is to provide a vibration-canceling mechanism and an HGA with the vibration canceling, whereby a configuration of a servo circuit of an actuator can be simplified.  
           [0009]    According to the present invention, a vibration-canceling mechanism includes a vibration transfer member. At least part of the vibration transfer member is inserted between a vibration-origination system having at least one resonance frequency and an object to which a vibration is applied from the vibration-origination system. The vibration transfer member has a resonance frequency equal to or near the at least one resonance frequency of the vibration-origination system. One end section of the vibration transfer member is fixed to the vibration-origination system and the other end section of the vibration transfer member is fixed to the object so that an apparent vibration of the object is substantially canceled by a resonance of the vibration transfer member.  
           [0010]    When the vibration-origination system resonates, the vibration transfer member also resonates. The one end section of the vibration transfer member vibrates in phase with the vibration-origination system but the other end section of the vibration transfer member vibrates in substantially inverted phase or deviated phase as the vibration-origination system. Therefore, the vibration transfer m operates so as to move a position of the object back to its original position that will be positioned when no resonance occurs, resulting the apparent vibration of the object to cancel.  
           [0011]    As aforementioned, according to the present invention, only by additionally attaching the vibration transfer member with a simple structure, the mechanical vibration can be extremely effectively canceled without greatly changing a conventional structure of the HGA. Also, since a configuration of a servo circuit of the actuator can be simplified, a manufacturing cost of the magnetic disk drive apparatus can be reduced.  
           [0012]    It is preferred that the vibration-canceling mechanism further includes a first damper layer provided between the other end section of the vibration transfer member and the vibration-origination system, for attenuating the vibration of the object. To the both surfaces of the first damper layer, vibrations of substantially inverted phase or deviated phase with each other are applied from the vibration-origination system and the vibration transfer member, respectively. Thus the first damper layer operates to restrict an excessive inverse-movement of the vibration transfer member so as to attenuate the amplitude of the vibration, and therefore the vibration of the object fixed to the other end section of the vibration transfer member is attenuated.  
           [0013]    It is also preferred that the vibration-canceling mechanism further includes a second damper layer provided between the one end section of the vibration transfer member and the object, for attenuating the vibration of the object.  
           [0014]    Preferably, the first and/or second damper layer is formed by a flexible resin adhesive adhered to the vibration transfer member and to the vibration-origination system.  
           [0015]    Also it is preferred that the vibration-canceling mechanism is configured to apply a load in an up-and-down direction to the first and/or second damper layer. By applying the load, the damping effect of the damping layer will increase. The resonance frequency of a system consisting of the vibration transfer member and the damper layer varies depending upon a level of the applied load.  
           [0016]    It is preferred that the vibration-origination system is a support member including a suspension, and that the object is a head slider with at least one head element attached to a top end section of the suspension.  
           [0017]    It is further preferred that the head slider is fixed to one surface of the vibration transfer member and the suspension is fixed to the other surface of the vibration transfer member. Since the first damper layer is provided between the other end section of the vibration transfer member and the suspension, a gap space for inserting an adhesive can be automatically obtained between the vibration transfer m and the suspension. This results extremely easy assembling of the vibration transfer member with the suspension. Also, if the second damper layer is provided between the one end section of the vibration transfer member and the head slider, a gap space for inserting an adhesive can be automatically obtained between the vibration transfer member and the head slider. This results extremely easy assembling of the vibration transfer member with the head slider.  
           [0018]    It is preferred that the vibration transfer b has a U-shaped section structure formed by bending a single metal plate.  
           [0019]    It is also preferred that the vibration transfer member includes a pair of arm sections each formed by a metal plate to be substantially in parallel with a side surface of the head slider, a first coupling section connected between the pair of arm sections at the other end section and formed by a metal plate to be substantially in parallel with a surface of the head slider, the surface being opposite to an air bearing surface (ABS) of the head slider, and a second coupling section connected between the pair of arm sections at the one end section and formed by a metal plate to be substantially in parallel with the first coupling section.  
           [0020]    It is further preferred that the at least one head element is at least one thin-film magnetic head element.  
           [0021]    According to the present invention, furthermore, an HGA includes a head slider provided with at least one head element, a support member including a suspension and having at least one resonance frequency, and a vibration transfer. At least part of the vibration transfer member is inserted between the suspension and the head slider to which a vibration is applied from the support member. The vibration transfer member has a resonance frequency equal to or near the at least one resonance frequency of the support member. A rear end section of the vibration transfer member is fixed to the suspension and a top end section of the vibration transfer member is fixed to the head slider so that an apparent vibration of the head slider is substantially canceled by a resonance of the vibration transfer member.  
           [0022]    When the suspension (load beam) resonates to vibrate the flexure, the vibration transfer member also resonates. The rear end section of the vibration transfer member vibrates in phase with the flexure but the top end section of the vibration transfer member vibrates in substantially inverted phase or deviated phase as the flexure. Therefore, the vibration transfer member operates so as to move a position of the head slider back to its original position that will be positioned when no resonance occurs, resulting the apparent vibration of the head slider to cancel.  
           [0023]    As aforementioned, according to the present invention, only by additionally attaching the vibration transfer member with a simple structure, the mechanical vibration can be extremely effectively canceled without greatly changing a conventional structure of the HGA. Also, since a configuration of a servo circuit of the actuator can be simplified, a manufacturing cost of the magnetic disk drive apparatus can be reduced.  
           [0024]    It is preferred that the HGA further includes a first damper layer provided between the top end section of the vibration transfer member and the suspension, for attenuating the vibration of the head slider. To the both surfaces of the first damper layer, vibrations of substantially inverted phase or deviated phase with each other are applied from the flexure and the vibration transfer member, respectively. Thus the first damper layer operates to restrict an excessive inverse-movement of the vibration transfer member so as to attenuate the amplitude of the vibration, and therefore the vibration of the head slider fixed to the top end section of the vibration transfer member is attenuated.  
           [0025]    It is preferred that the HGA further includes a second damper layer provided between the rear end section of the vibration transfer member and the head slider, for attenuating the vibration of the head slider.  
           [0026]    It is also preferred that the first and/or second damper layer is formed by a flexible resin adhesive adhered to the vibration transfer member and to the suspension.  
           [0027]    It is further preferred that the HGA is configured to apply a load in an up-and-down direction to the first and/or second damper layer. In the actual HGA, a load from the suspension is applied to the vibration transfer member and a resistance force from the recoding disk is applied to the head slider. Thus, forces in up-and-down directions are applied to the damper layer, and therefore the damping effect of the damping layer increases. The resonance frequency of a system consisting of the vibration transfer member and the damper layer varies depending upon a level of the applied load.  
           [0028]    It is preferred that the head slider is fixed to one surface of the vibration transfer member and the suspension is fixed to the other surface of the vibration transfer member. Since the first damper layer is provided between the top end section of the vibration transfer member and the suspension, a gap space for inserting an adhesive can be automatically obtained between the vibration transfer member and the suspension. This results extremely easy assembling of the vibration transfer member with the suspension. Also, if the second damper layer is provided between the rear end section of the vibration transfer member and the head slider, a gap space for inserting an adhesive can be automatically obtained between the vibration transfer member and the head slider. This results extremely easy assembling of the vibration transfer member with the head slider.  
           [0029]    It is also preferred that the vibration transfer member has a U-shaped section structure formed by bending a single metal plate.  
           [0030]    It is further preferred that the vibration transfer member includes a pair of arm sections each formed by a metal plate to be substantially in parallel with a side surface of the head slider, a top end coupling section connected between the pair of arm sections at the top end section and formed by a metal plate to be substantially in parallel with a surface of the head slider, the surface being opposite to an ABS of the head slider, and a rear end coupling section connected between the pair of arm sections at the rear end section and formed by a metal plate to be substantially in parallel with the top end coupling section.  
           [0031]    It is still further preferred that the at least one head element is at least one thin-film magnetic head element. 
       
    
    
       [0032]    Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.  
       BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]    [0033]FIG. 1 is an oblique view schematically illustrating main components of a magnetic disk drive apparatus in a preferred embodiment according to the present invention;  
         [0034]    [0034]FIG. 2 is an oblique view illustrating the whole structure of an HGA in the embodiment of FIG. 1;  
         [0035]    [0035]FIG. 3 is an exploded oblique view illustrating an enlarged top end section of the HGA, namely a flexure, a vibration transfer member and a magnetic head slider, in the embodiment of FIG. 1;  
         [0036]    [0036]FIG. 4 is an exploded oblique view illustrating the enlarged top end section of the HGA in the embodiment of FIG. 1, seen from a different direction from FIG. 3;  
         [0037]    [0037]FIG. 5 is an exploded oblique view illustrating the enlarged top end section of the HGA in the embodiment of FIG. 1, seen from a different direction from FIG. 3;  
         [0038]    [0038]FIG. 6 is an exploded side view illustrating the enlarged top end section of the HGA in the embodiment of FIG. 1;  
         [0039]    [0039]FIG. 7 is an oblique view illustrating the enlarged top end section of the HGA in the embodiment of FIG. 1;  
         [0040]    [0040]FIG. 8 is an oblique view illustrating the enlarged top end section of the HGA in the embodiment of FIG. 1, seen from a different direction from FIG. 7;  
         [0041]    [0041]FIG. 9 is a side view illustrating the enlarged top end section of the HGA in the embodiment of FIG. 1;  
         [0042]    [0042]FIG. 10 is a plane view used for illustrating why a mechanical vibration is cancelled in the embodiment of FIG. 1;  
         [0043]    [0043]FIG. 11 is a side view used for illustrating why a mechanical vibration is cancelled in the embodiment of FIG. 1; and  
         [0044]    [0044]FIG. 12 is an exploded oblique view illustrating an enlarged top end section of an HGA in another embodiment according to the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0045]    [0045]FIG. 1 illustrates main components of a magnetic disk drive apparatus in a preferred embodiment according to the present invention, FIG. 2 illustrates the whole structure of an HGA in this embodiment, FIG. 3 illustrates an enlarged top end section of the HGA in this embodiment, FIGS. 4 and 5 illustrate the enlarged top end section of the HGA in this embodiment, seen from a different direction from FIG. 3, FIGS. 6 and 7 illustrate the enlarged top end section of the HGA in this embodiment, FIG. 8 illustrates the enlarged top end section of the HGA in this embodiment, seen from a different direction from FIG. 7, and FIG. 9 illustrates the enlarged top end section of the HGA in this embodiment.  
         [0046]    In FIG. 1, reference numeral  10  denotes a plurality of magnetic hard disks rotating around an axis  11 , and  12  denotes an assembly carriage device for positioning each magnetic head element on a track of each disk. The assembly carriage device  12  is mainly constituted by a carriage  14  capable of rotating around an axis  13  and an actuator  15  such as for example a VCM for driving the carriage  14  to rotate.  
         [0047]    Base sections at one ends of a plurality of drive arms  16  stacked along the axis  13  are attached to the carriage  14 , and one or two HGAs  17  are mounted on a top section at the other end of each arm  16 . Each of the HGAs  17  has a magnetic head slider mounted at its top end section so that the slider opposes to one surface (recording and reproducing surface) of each of the magnetic disks  10 .  
         [0048]    As shown in FIG. 2, the HGA is assembled by fixing a vibration transfer member  21  to which a magnetic head slider  22  with a thin-film magnetic head element  22   d  (FIGS. 3 and 4) is fixed, to a top end section of a suspension  20 . Namely, the magnetic head slider  22  is indirectly coupled with the suspension  20  through the vibration transfer member  21 .  
         [0049]    As shown in FIGS.  3 - 9 , the magnetic head slider  22  has a rear end surface  22   a  on which the thin-film magnetic head element  22   d  is formed, an ABS  22   b  and a surface  22   c  opposite to the ABS  22   b . This opposite surface  22   c  is tightly fixed to the vibration transfer member  21 .  
         [0050]    The suspension  20  is substantially formed by a resilient flexure  23 , a load beam  24  supporting a rear end section of this flexure  23 , and a base plate  25  fixed to the load beam  24 .  
         [0051]    The flexure  23  has at its top end section a flexible tongue  23   a  (FIGS.  3 - 9 ) provided with a proper stiffness and depressed by a dimple (not shown) formed on the load beam  24 . Onto the tongue  23   a , fixed is a rear coupling section  21   a  (FIG. 3) of the vibration transfer member  21 .  
         [0052]    The flexure  23  has elasticity for supporting flexibly the magnetic head slider  22  through the vibration transfer member  21  by this tongue  23   a . This flexure  23  is made of in this embodiment a stainless steel plate (for example SUS304TA) with a thickness of about 20 μm.  
         [0053]    The load beam  24  is made of in this embodiment a stainless steel plate with a thickness of about 60 μm, and fixed to the flexure  23  at its rear end section. The fixing of the load beam  24  with the flexure  23  is performed also by pinpoint welding at a plurality of points.  
         [0054]    The base plate  25  to be attached to the drive arm  16  shown in FIG. 1 is made of in this embodiment a stainless steel or iron plate with a thickness of about 150 μm. This base plate  25  is fixed to a base section of the load beam  24  by welding.  
         [0055]    On the flexure  23  and the load beam  24 , flexible conductor members each including a plurality of trace conductors of a thin-film multi-layered pattern are formed or disposed. However, as the present invention does not directly concern these components, they are omitted in the drawings.  
         [0056]    It is apparent that a structure of the suspension of the HGA according to the present invention is not limited to the aforementioned one. Although it is not shown, a head drive IC chip may be mounted on a middle of the suspension  20 .  
         [0057]    As shown in FIGS.  3 - 9 , the vibration transfer member  21  in this embodiment is formed by cutting out a single metal plate member in a ladder shape, and by bending it into three-dimensional shape. Namely, each member cut out in a ladder shape is substantially perpendicularly bent along lines inside from the both side edges of a strip-shaped rear end coupling section  21   a  and a strip-shaped top end coupling section  21   b . Thus, a pair of arm sections  21   c  and  21   d  of the vibration transfer member  21  run in parallel with each other keeping substantially perpendicular to the coupling sections  21   a  and  21   b . Since the vibration transfer member  21  is formed by bending at inside positions from the side end edges of the coupling sections  21   a  and  21   b , each of the arm sections  21   c  and  21   d  is shaped in a strip-shaped plane plate. These arm sections  21   c  and  21   d  are in parallel with side surfaces of the magnetic head slider  22  and freely movable without contact to the magnetic head slider  22  and also to the flexure  23 . The coupling sections  21   a  and  21   b  are formed in parallel to the surface  22   c  that is opposite to the ABS  22   b  of the magnetic head slider  22 .  
         [0058]    The metal plate for the vibration transfer member  21  in this embodiment is made of a stainless steel and has a thickness of about 10-100 μm. As for the metal plate, any metal material plate such as a zirconia plate, a beryllium copper plate, an aluminum plate, a titanium plate, another metal plate or an alloy plate may be used other than the stainless steel plate.  
         [0059]    An upper surface of the rear end coupling section  21   a  of the vibration transfer member  21  is tightly fixed to a lower surface of the tongue  23   a  of the flexure  23  by an adhesive  26 , and a lower surface of the top end coupling section  21   b  is also tightly fixed to the opposite surface  22   c  of the magnetic head slider  22  by an adhesive  27 . Thus, the magnetic head slider  22  is coupled to the flexure  23  through the vibration transfer member  21 . As for the adhesive  26  and  27 , a cured type adhesive such as for example an epoxy base or UV-cured adhesive may be used.  
         [0060]    An upper surface of the top end coupling section  21   b  of the vibration transfer member  21  is fixed to a top end section of the flexure  23 , namely a base section of the tongue  23   a , by a soft or flexible adhesive that functions as a damping layer  28 . As for the flexible adhesive  28 , a resin adhesive such as a urethane-rubber base or acryl base pressure-sensitive adhesive for example may be used. Thus formed damping layer  28  can effectively attenuate amplitude of lateral vibrations of the magnetic head slider  22  due to a resonance in a lateral direction of the suspension (in a direction perpendicular to an axis in the plane).  
         [0061]    [0061]FIGS. 10 and 11 illustrate why a mechanical vibration is cancelled in this embodiment. In particular, FIG. 11 illustrates in detail a system  102  shown in FIG. 10.  
         [0062]    As shown in FIG. 10, when the actuator and the drive arm  16  connected to the actuator mechanically vibrate at a frequency f, the load beam  24  resonates at a resonance frequency f and a vibration  101  in track-width directions appeared at the top end of the load beam  24  is applied to the system  102  connected with this vibration-origination system  100 . In the system  102  shown in FIG. 11, this lateral vibration  101  is first applied to the flexure  23 . However, because a resonance frequency of the flexure  23  is sufficiently higher than the frequency f of the vibration, the flexure  23  will not resonate. Therefore, the flexure  23  in regions  110  and  111  will vibrate with the same phase. Here, the top end section of the vibration transfer member  21  positions in the region  110  and the rear end section of the vibration transfer member  21  positions in the region  111 .  
         [0063]    This vibration transfer member  21  fixed to the flexure  23  in the region  111  will receive the vibration from the flexure  23  and vibrate with the same phase as the flexure  23 . A resonance frequency of the vibration transfer member  21  itself is set to just or near the frequency f. Thus, when the vibration at the frequency f is applied from the flexure  23 , this vibration transfer member  21  will resonate. Because of the resonance, a vibration at the top end section of the vibration transfer member  21  in a region  112  will have an inverted phase as that of the flexure  23  in the region  110 . Therefore, the vibration transfer member  21  will operate so as to move a position of the magnetic head slider  22  fixed to the vibration transfer member  21  in the region  112  back to its original position that will be positioned when no resonance occurs resulting the apparent vibration of the magnetic head slider  22  to cancel.  
         [0064]    In this embodiment, also, the damping layer  28  operates to attenuate the vibration amplitude of the magnetic head slider  22 . Namely, since the flexure  23  in the region  110  and the vibration transfer member  21  in the region  112  which sandwich the damping layer  28  move in reverse directions and provide resistances with each other, the vibration amplitude of the vibration transfer member  21  or the magnetic head slider  22  will be attenuated. This attenuation of the amplitude will be established in a frequency range near the resonance frequency, in which phases of both the vibrations are inverted to or deviate from each other.  
         [0065]    It is desired to apply a load or loads in up-and-down directions to the damping layer  28 . In fact, in the actual HGA, a load from the flexure  23  is applied to the vibration transfer member  21  and a resistance force from the recoding disk is applied to the magnetic head slider  22 . Thus, forces in up-and-down directions are applied to the damper layer  28 . By applying the forces, the damping effect of this damping layer  28  will increase.  
         [0066]    As in this embodiment, even if the vibration transfer member  21  is formed by a stainless steel, a relatively low resonance frequency of the vibration transfer member  21 , which is substantially equal to a swaying mode frequency of the HGA, can be attained by arranging this vibration transfer member  21  in a top-and-rear direction that is perpendicular to the direction of the applied vibration and by appropriately adjusting a length and a thickness of the vibration transfer member  21 .  
         [0067]    As aforementioned, according to this embodiment, only by additionally attaching the vibration transfer member  21  with a simple structure, for providing a vibration-transferring loop between the tongue  23   a  of the flexure  23  and the magnetic head slider  22 , the mechanical vibration can be extremely effectively canceled without greatly changing a conventional structure of the HGA. Also, since a configuration of a servo circuit of an actuator can be simplified, a manufacturing cost of the magnetic disk drive apparatus can be reduced.  
         [0068]    The damping layer  28  in this embodiment is provided to restrict an excessive inverse-movement of the vibration transfer member  21  so as to attenuate the amplitude of the vibration. Thus, providing of this damping layer is not a necessary condition of the present invention. However, if the damping layer is provided, not only the vibration amplitude of the magnetic head slider  22  can be effectively attenuated, but also a gap space for inserting an adhesive can be automatically obtained between the rear end coupling section  21   a  of the vibration transfer member  21  and the flexure  23  resulting extremely easy assembling of the vibration transfer member  21  with the flexure  23 .  
         [0069]    [0069]FIG. 12 illustrates an enlarged top end section of an HGA in another embodiment according to the present invention.  
         [0070]    In this embodiment, a lower surface of the rear end coupling section  21   a  of the vibration transfer member  21  is fixed to the surface  22   c  opposite to the ABS  22   b  of the magnetic head slider  22  by a soft or flexible adhesive that functions as a damping layer  29 . As for the flexible adhesive  29 , a resin adhesive such as a urethane-rubber base or acryl base pressure-sensitive adhesive for example may be used. Since the slider  22  vibrates in response to the vibration of the top end section of the vibration transfer member  21 , both the resonance vibration at the rear end section of the vibration transfer member  21  and the resonance vibration at the top end section of the vibration transfer member  21  that have phases inverted to each other or deviated from each other are applied to this damper layer  29 . Thus, they provide resistances with each other and then amplitude of vibrations of the magnetic head slider  22  is attenuated.  
         [0071]    Since the damping layer  29  is provided between the rear end coupling section  21   a  of the vibration transfer member  21  and the magnetic head slider  22 , a gap space for inserting an adhesive can be automatically obtained between the vibration transfer member  21  and the slider  22  resulting extremely easy assembling of the vibration transfer member  21  with the magnetic head slider  22 .  
         [0072]    Other configurations, operations, advantages and modifications in this embodiment are the same as those in the embodiment of FIG. 1. Also, in this embodiment, the similar elements as those in the embodiment of FIG. 1 are represented by the same reference numerals.  
         [0073]    Structure of the vibration transfer member is not limited to those of the aforementioned embodiments. Any shaped vibration transfer member provided with a U-shaped section ready for a lateral directional resonance may be utilized.  
         [0074]    In the aforementioned embodiments, HGAs having magnetic head sliders with thin-film magnetic head elements are described. However, it is apparent that the present invention can be applied to an HGA with a head element such as an optical head element other than the thin-film magnetic head element.  
         [0075]    Many widely different embodiments of the present invention may be constructed without departing from the spirit and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments described in the specification, except as defined in the appended claims.