Abstract:
A microactuator suspension assembly has a load beam structure with at least three layers of material in certain portions of the proximal area between the baseplate area and the spring area, the first and third layers comprising substantially inextensible metal, the second layer comprising extensible plastic, the plastic layer operating in shear when driven by an electrodynamically variable microactuator to make a microadjustment of the suspension.

Description:
RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application Ser. No. 60/309,825, filed Aug. 1, 2001. 
    
    
     STATEMENT REGARDING FEDERALLY SP 3 NSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     REFERENCE TO A MICROFICHE APPENDIX 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to disk drive suspensions, and more particularly to such suspensions having microactuated movement transmitted between proximal and distal portions via relative movement between outer layers of a laminate bonded to a common inner layer that moves in shear to accommodate the relative movement. Attachment of the proximate portion to one outer layer and the distal portion to the other outer layer and effecting a relative shift in these layers with a microactuator coupled to both outer layers will shift the distal portion relative to the proximate portion and make a microadjustment of the suspension. The microactuator extends through the plane of the laminate to attach to oppositely facing outer layer surfaces. 
     2. Description of the Related Art 
     Microactuated suspensions are able to microadjust for better tracking on a disk. One or two microactuators are used coupled between the fixed and the movable portions of a suspension to effect relative movement of these portions. The movement is achieved by bending one or both of the metal members that define the proximate and distal portions. The energy required to do this is a design limitation. The reduction in metal thickness in the area of bending is a further design problem. 
     BRIEF SUMMARY OF THE INVENTION 
     With reduced size of suspensions and new materials, such as laminates, being used, e.g. as flexible circuits and as circuit supports, that do not lend themselves to conventional microactuation approaches, the invention adapts these new materials and combines them with microactuators to take advantage of their unique properties to better effect microactuation at lower cost of manufacture, and to minimize design compromises in the suspension parts. 
     It is an object, therefore, to provide a disk drive suspension using a laminate of first and second metal outer layers and a middle layer comprised of plastic such as polyimide. It is a further object to provide microactuation using as a typical laminate one comprised of a first outer layer of stainless steel about 0.0012 inch thick, a middle layer of plastic such as about 0.008 inch polyimide, and a second outer layer of stainless steel about 0.002 inch thick. It is a further object to form a suspension member of a three layer laminate, using one outer layer as or connected to the proximate portion of the suspension, the other outer layer as or connected to the suspension distal portion, coupling microactuators to the two outer layers while traversing the middle layer, and effecting relative movement between the outer layers without bending metal parts, only elongating or contracting the plastic middle layer, to cause microadjustment between the outer layers and thus the proximate and distal portions. It is a further object to provide a new microadjustment system for microactuated suspensions. The relatively thick middle layer, combined with its low modulus of elasticity, means that the microactuating PZTs (piezoelectric crystals) can drive the motion in shear mode instead of bending mode. 
     These and other objects of the invention to become apparent hereinafter are realized in a microactuated disk drive suspension comprising a first outer layer-plastic layer-second outer layer laminate, the plastic layer extending in a plane, a dimensionally variable microactuator having first and second end regions and a middle region extending through the plastic layer plane, the first and second outer layers mounting the microactuator by the first and second end regions respectively, whereby dimensional variations in the microactuator relatively shift the outer layers as a function of plastic layer movement in shear. 
     In this and like embodiments, typically, the first outer layer comprises a metal, the second outer layer comprises a metal, or both the first and second outer layers comprise metal, at least one of the first and second outer layers comprises a conductive metal, such as stainless steel, aluminum and copper, the plastic layer material is a synthetic organic polymer, such as one comprising repeating imide or acrylic moieties, there is a second microactuator having first and second end regions, and a middle region extending through the plane of the plastic layer, the suspension is combined with a flexible circuit, the laminate is apertured to pass the microactuator through the plastic layer plane. 
     In a further embodiment, the invention provides a microactuated disk drive suspension comprising a laminate of a first metal layer, a second metal layer and a synthetic organic plastic layer fixed therebetween, the plastic layer having a first surface fixed to the first metal layer and a second surface fixed to the second metal layer, the plastic layer having a thickness permitting relative movement between the first and second surfaces, a longitudinally dimensionally variable electrodynamic microactuator having first and second end regions and a middle region therebetween, the microactuator being fixed at its first end region to the first metal layer and at its second end region to the second metal layer with its middle region passing through the plastic layer, whereby microactuator dimensional variations shift the first metal layer relative to the second metal layer as a function of relative movement within the plastic layer between the first and second metal layers. 
     In a further embodiment, the invention provides a microactuated disk drive suspension member having proximate and distal portions and comprising a laminate of first and second substantially inextendable outer layers and a substantially extendable third inner layer dimensionally responsive to shearing forces, the member having an aperture with spaced distal and proximate edge margins in the first outer layer and spaced distal and proximate edge margins in the second outer layer, the first and second outer layers defining on their respective distal and proximate edge margins oppositely facing attachment regions, a microactuator structure that traverses the plane of the inner layer, the microactuator structure having first and second end regions fixed to respective first and second outer layer distal and proximate edge margins so as to act between the first and second outer layers with the third inner layer response to shearing forces to shift the member distal portion relative to the member proximate portion. 
     In this and like embodiments, typically, the first outer layer comprises a metal, and or the second outer layer comprises a metal, and third inner layer comprises a plastic material such as a synthetic organic polymer comprising repeating imide or acrylic moieties, the metal layers can comprise a conductive metal such as stainless steel, aluminum or copper, the member is combined with a microactuator, and or a flexible circuit, the member is combined with a pair of laterally spaced microactuators, the aperture is generally rectangular, and the member is combined with a flexible circuit. 
     In a further embodiment, the invention provides a disk drive suspension comprising a flexible circuit comprising a laminate of at least one pair of conductors, an insulative film and a support layer that defines a flexure, and an elongated member supporting the flexible circuit, the elongated member having a proximal end adapted to be mounted to an actuator and a distal end supporting the flexure to carry a read/write head in operating proximity to a disk, the member comprising an assembly of juxtaposed first and second layers that are substantially inextendable by shear forces, at least one of the first and second layers being coupled to the distal end, and a third layer between and attached to both the first and second layers, the third layer being longitudinally variable in response to shear forces, and an elongated microactuator arranged to relatively move the first and second layers in shear force imparting relation to the third layer to relatively shift the first and second layers and thereby correspondingly shift the distal end carried head relative to the disk. 
     In yet another embodiment, the invention provides a microactuated disk drive suspension for supporting a read/write head at a disk, the suspension comprising an elongated member comprising a laminate of first and second outer layers of substantially inextendable material and a third inner layer of substantially extendable material bonded to the first and second outer layers, the member having a proximate portion adapted to attach the member to an actuator, a distal portion adapted to support the read/write head, and an intermediate portion connected between the proximate and distal portions; and microactuator structure attached to the intermediate portion and connected to the first and second outer metal layers for shifting the first and second outer metal layers relative to each other with the response to shear forces of the inner layer in a manner shifting the distal portion-carried read/write head relative to the disk. 
     In this and like embodiments, typically, at least one of the outer layers is comprised of metal such as stainless steel, copper or aluminum, the member proximate portion comprises the first outer layer, the member distal portion comprises the second outer layer, the member distal portion further comprises the third inner layer, the third inner layer comprising plastic, the member distal portion further comprises the first outer layer, the first outer layer comprising a metal, there is also included a spring portion fixed between the proximate and the distal portions, and there is further included a flexible circuit laminate comprising conductive traces, an insulative film layer and a metal support layer, the metal support layer defining the spring portion. 
     Further in this and like embodiments, there is included a spring portion having a proximate part and a distal part, the second outer layer having a distal part fixed to the proximate part of the spring portion, the second outer layer distal part acting on the spring portion distal part through the spring portion in response to relative movement of the first outer layer and the second outer layer across the third inner layer effected by the microactuator, and there is also included a flexible circuit laminate of conductive traces, an insulative film layer and a metal support layer, the metal support layer defining the spring portion. 
     In a further embodiment, the invention provides a microactuated disk drive suspension for supporting a read/write head at a disk, the suspension comprising an elongated member comprising a laminate of first and second outer metal layers and a third inner layer of substantially extendable plastic material bonded to the first and second outer layers, the member having a proximate portion adapted to attach the member to an actuator, the proximate portion having a generally planar central area and defining in the central area a structure for attaching the member to an actuator arm, the proximate portion having left and right edge rails rising from the central area; the member having a distal portion adapted to support the read/write head, and an intermediate portion connected between the proximate and distal portions, the intermediate portion comprising the laminate layers shaped to define left and right raised edges. 
     In a further embodiment, there is provided a microactuator suspension assembly comprising a load beam structure having side rails and comprising at least three layers of material in certain portions of the proximal area between the baseplate area and the spring area, the first and third layers comprising substantially inextensible metal, the second layer comprising extensible plastic, the plastic layer operating in shear when driven by an electrodynamically variable microactuator to extend or contract the length of the side rails. 
     In its method aspects, the invention provides a method of shifting a slider at a disk including carrying the slider on a suspension rigid portion, providing the rigid portion from a metal layer of a laminate having two metal layers and plastic layer therebetween having movement in response to shear forces, coupling the two metal layers together with a microactuator extending through the plane of the plastic layer, and oppositely driving the rigid portion metal layers responsive to movement in shear in the plastic film layer to shift the slider at the disk with the microactuator. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The invention will be further described in conjunction with the attached drawings in which: 
         FIG. 1  is an oblique view of the invention suspension member; 
         FIG. 2  is an oblique view of the invention suspension member in another embodiment; and, 
         FIG. 3  is a bottom plan view of the suspension in a further embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference now to the drawings in detail, in  FIG. 1  microactuated disk drive suspension  10  comprises a laminate  12  of a first outer layer  14 , a middle plastic layer  16 , and a second outer layer  18 . Plastic layer  16  extends in a plane P. A dimensionally variable microactuator  22 , attached to laminate  12  has first and second end regions  24 ,  26 , respectively, and a middle region  28  extending through the plastic layer plane P. First and second outer layers  14 ,  18  mount the microactuator  22 , comprising one or two microactuators, as shown, by first and second end regions  24 ,  26  respectively, so that dimensional variations in the microactuator relatively shift the outer layers as a function of plastic layer  16  movement in shear. 
     First and second outer layer  14  typically comprise a metal, such as a conductive metal, e.g. stainless steel, aluminum or copper. The plastic layer  16  material is typically a synthetic organic polymer, such as one comprising repeating imide or acrylic moieties. Laminate  12  is apertured at  20  to pass the microactuator  22  through the plastic layer plane P. 
     The plastic layer  16  has a first surface  32  fixed to the first metal layer  14  and a second surface  34  fixed to the second metal layer  18 . Plastic layer  16  has a thickness t permitting relative movement between the first and second surfaces as a function of the movement of metal layers  14 ,  18  attached to those surfaces. The longitudinally dimensionally variable electrodynamic microactuator  22  is fixed at its first end region  24  to the first metal layer  14  and at its second end region  26  to the second metal layer  18  with its middle region  28  passing through the plane of the plastic layer  16 . Microactuator  22  dimensional variations shift the first metal layer  14  relative to the second metal layer  18  as a function of relative movement within the plastic layer  16  between first and second metal layers to shift suspension distal portion  44  accordingly by force against suspension spring portion distal part  15 . 
     With reference to  FIG. 2 , wherein like parts have like numeral plus  100 , microactuated disk drive suspension member  110  has proximate and distal portions  142 ,  144 , respectively, each comprising a laminate  112  of first and second substantially inextendable outer layers  114 ,  118 , and a substantially extendable third inner layer  116  dimensionally responsive to shearing forces. Suspension member  110  has a generally rectangular aperture  46  with a distal edge margin  48  and spaced therefrom a proximate edge margin  52  in the first outer layer  114 . Suspension member  110  further has distal edge margin  68  and proximate edge margin  72  in the second outer layer  118 . First and second outer layers  114 ,  118  define on their respective distal and proximate edge margins  58 ,  62 ,  68 ,  72  oppositely facing attachment regions  64 ,  74 . Microactuator structure  122  traverses the plane P of the inner layer  116 , having first and second end regions  124 ,  126  fixed to respective first and second outer layer distal and proximate edge margins  58 ,  62 ,  68 ,  72  so as to act between the first and second outer layers  114 ,  118  with the third inner layer  116  response to shearing forces to shift the member distal portion  142  relative to the member proximate portion  144 . Suspension member  110  is typically combined with microactuators  122 , typically laterally spaced as shown, and a flexible circuit  82  (FIG.  3 ), hereinafter more particularly described. 
       FIG. 1  shows the metal layers  14 ,  18  bent at their left and right edge margins  75 ,  77  to form rails  84 ,  86 . In this embodiment, the metal layers  14 ,  18  are cut away in the proximate and distal portions  42 ,  44  so that the laminate is left in the rails  84 ,  86 , thus concentrating in middle layer  16  the shear forces resulting from opposite longitudinal movements in first and second outer layers  14 ,  18  under dimensional elongation or contraction of the microactuators  22 . 
     In  FIG. 2 , the edge margins  175 ,  177  of metal layers  114 ,  118  are flat, not bent into rails, and adhered to one another by middle layer  116 . 
     In  FIG. 3 , a further embodiment is shown in which like parts have like numbers plus  300 . There, disk drive suspension  310  comprises a flexible circuit  82  comprising a laminate  88  of at least one pair of trace conductors  92 , an insulative layer  93  of a plastic material or film, and a support layer  94  that defines a flexure  96  that carries slider (head)  45 . Elongated suspension member  310  supports the flexible circuit  82 . Suspension member  310  has a proximal end  98  adapted to be mounted to an actuator 45 and a distal end  102  supporting the flexure  96  to carry a read/write head (not shown) in operating proximity to a disk (not shown). Suspension member  310  comprises an assembly of juxtaposed first and second layers  314 ,  318  that are substantially inextendable by shear forces, at least one of the first and second layers being coupled to the distal end  102 , and a third layer  316  between and attached to both the first and second layers. Third layer  316  is longitudinally variable in response to shear forces. An elongated microactuator  322  is arranged to relatively move the first and second layers  314 ,  318  in shear force imparting relation to the third layer  316  to relatively shift the first and second layers and thereby correspondingly shift the distal end  102  carried head relative to the disk. 
     In the  FIG. 3  embodiment suspension member  310  includes a spring portion  311  having a proximate part  313  and a distal part  315 . The member second outer layer  318  has a distal part  317  fixed to the proximate part  313  of the spring portion  311 . The second outer layer distal part  317  acts on the spring portion distal part  315  through the spring portion  311  in response to relative movement of the  314  first outer layer and the second outer layer  318  across the third inner layer  316  effected by the microactuator  322 . 
     The suspension  310  includes as well flexible circuit laminate  88  of trace conductors  92 , an insulative plastic material layer or film  93  and a metal support layer  94 . Metal support layer  94  conveniently but not necessarily defines the spring portion  311 . In this embodiment, and the embodiments of  FIGS. 1 and 2 , a transverse stiffening element  321  is formed in the first outer layer  314  against curling of the suspension member  310  adjacent the spring portion  311 . 
     The invention method of shifting a slider at a disk includes, with reference to  FIG. 3 , carrying a slider  45  on a suspension rigid portion  47 , providing the rigid portion from a metal layer  314  of a laminate  312  having two metal layers  314 ,  318  and plastic layer  316  therebetween having movement in response to shear forces, coupling the two metal layers together with a microactuator  322  extending through the plane P of the plastic layer, and oppositely driving the rigid portion metal layers  314 ,  318  responsive to movement in shear in the plastic layer to shift the slider  45  at the disk (not shown) with the microactuator. 
     The invention thus provides a disk drive suspension using a laminate of first and second metal outer layers and a middle layer comprised of plastic such as polyimide, using one outer layer as or connected to the proximate portion of the suspension, and the other outer layer as or connected to the suspension distal portion, and coupling microactuators to the two outer layers while traversing the middle layer, and effecting relative movement between the outer layers without bending metal parts, only elongating or contracting the plastic middle layer, to cause microadjustment between the outer layers and thus the proximate and distal portions. 
     The foregoing objects are thus met.