Abstract:
An apparatus has an information storage medium with an information storage surface, and structure operable to effect relative movement of the head and surface within a first zone while maintaining the head adjacent the surface and while using the head to effect at least one of reading information from and writing information to the surface. A head cleaning section includes a cleaning part engageable with the head when the head is in a second zone where the head is spaced from the surface, the structure being operable to effect relative movement of the engaged head and cleaning part in a manner which includes a component of movement that is representative of an applied force subject to a damping influence.

Description:
This application claims the priority under 35 U.S.C. §119 of provisional application No. 60/425,928 filed Nov. 12, 2002. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     This invention relates in general to techniques for increasing the storage density of information stored by a storage medium and, more particularly, to techniques for cleaning a read/write head that transfers information to and from the storage medium. 
     BACKGROUND OF THE INVENTION 
     Over the past twenty years, computer technology has evolved very rapidly. One aspect of this evolution has been a progressively growing demand for increased storage capacity in memory devices. In order to provide high storage density at a reasonable cost, one of the most enduring techniques has been to provide a rotatable hard disk that includes a layer of magnetic material, and a read/write head which is supported for movement adjacent the disk. 
     In arrangements of this type, if the head is exposed to airborne dust, smoke, vapors or other contaminants, these contaminants can progressively build up on the head. Eventually, the buildup becomes sufficient to interfere with the interaction between the head and disk, thereby increasing the error rate until the device will not operate. In order to avoid this problem, most hard disk drives have the disk and head disposed within a sealed enclosure, so that the head and disk are not exposed to any airborne contaminants that may happen to be present externally of the enclosure. 
     This approach works well where the entire hard disk drive is permanently installed in a computer. In another type of system, however, a hard disk is provided in a removable cartridge, and it is desirable that the cartridge not include the read/write head. In this regard, there are advantages to placing a head stack assembly (HSA) and its support structure within the drive which receives the cartridge, rather than in the cartridge. For example, a typical user will have several removable cartridges for each drive. Thus, in terms of overall system cost, it is cheaper to provide a single head stack assembly and support in the drive, rather than to provide several separate head stack assemblies which are each disposed in a respective one of the many cartridges used with that drive. However, this presents problems in regard to keeping the head clean. 
     More specifically, in order to permit the head from the drive to access the disk within the cartridge, the cartridge is not provided with a sealed enclosure of the type discussed above. Instead, the cartridge is provided with an opening through which the head of the drive can be inserted into the cartridge. In some cases, a movable shutter is provided to obstruct the opening when the cartridge is not in the drive, but the shutter is open when the cartridge is in the drive. Thus, in either configuration, when the cartridge is in the drive, the opening gives not only the head but also ambient air access to the disk and head. Consequently, any dust, smoke, vapor or other contaminant carried by the ambient air can get inside the cartridge enclosure, and the operational surface of the head can quickly develop a buildup of contaminants. 
     The effect of this buildup can be ameliorated to some extent by keeping the storage density of the hard disk in the removable cartridge at a relatively low level, in comparison to the levels used for hard disks located within sealed enclosures. However, as mentioned above, the commercial marketplace is exhibiting a strong and progressively increasing demand for high-density storage in a removable cartridge. 
     A further consideration is that existing high-density read/write heads typically have an operational surface with recesses therein. While it is not too difficult to clean the outermost portions of the operational surface of such a head, it is more difficult to clean other portions of the surface which are within the shallow recesses. As contamination collects in the recesses, it can significantly degrade system operation. 
     SUMMARY OF THE INVENTION 
     From the foregoing, it may be appreciated that a need has arisen for a method and apparatus for effectively and efficiently cleaning a head which moves relative to an information storage surface, and which effects transfers of information to or from that surface. According to the present invention, a method and apparatus are provided to address this need, and relate to operation of an apparatus which includes an information storage medium having an information storage surface, structure which includes a head and can effect a transfer of information with respect to the surface, and a cleaning part. The method and apparatus involve: effecting relative movement of the head and surface within first and second zones that are mutually exclusive, the head being spaced from the surface when in the second zone; maintaining the head adjacent the surface and using the head to effect at least one of reading information from and writing information to the surface during relative movement of the head and surface within the first zone; causing the cleaning part to engage the head when the head is in the second zone and while effecting relative movement of the head and cleaning part in a manner which includes a component of movement representative of an applied force subject to a damping influence. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A better understanding of the present invention will be realized from the detailed description which follows, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a diagrammatic fragmentary top view of an apparatus which is part of a disk drive that embodies aspects of the present invention; 
         FIG. 2  is a diagrammatic view showing a cleaning pad, a flexible element and a damping part which are components of a head cleaning mechanism in the apparatus of  FIG. 1 ; 
         FIG. 3  is a diagrammatic view showing the cleaning pad, and showing a magnetic head which is a further component of the apparatus of  FIG. 1 ; 
         FIG. 4  is a diagrammatic view showing the magnetic head, and showing trace lines which represent paths of movement of asperities of the cleaning pad relative to the head during a head cleaning operation; 
         FIG. 5  is a view of a surface of the magnetic head with a coating which is a thin layer of gold; 
         FIG. 6  is a view of the magnetic head of  FIG. 5  after a cleaning operation, and shows trace lines produced in the gold layer by asperities of the cleaning pad during the head cleaning operation; 
         FIG. 7  is a graph showing two curves which respectively represent displacement of the cleaning pad and displacement of the magnetic head during a cleaning cycle; 
         FIG. 8  is a diagrammatic perspective view of an apparatus in the form of a head cleaning mechanism, which is an alternative embodiment of the head cleaning mechanism in the apparatus of  FIG. 1 ; and 
         FIG. 9  is a diagrammatic perspective exploded view of the apparatus of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a diagrammatic fragmentary top view of an apparatus which is part of a disk drive  10  and which embodies aspects of the present invention. The disk drive  10  includes a rotably supported hard disk  12  which has a magnetic surface on an upper side thereof. The hard disk  12  is rotated by a not-illustrated motor of a known type. An arm  14  is fixedly supported on a pivot axle  16 , and the pivot axle  16  can be pivoted by a not-illustrated actuator of a known type. Pivotal movement of the axle  16  causes pivotal movement of the arm  14  in directions indicated by two arrows  18  and  19 . 
     At an outer end of the arm  14  is a suspension  21  of a known type. The suspension  21  has at its outer end a radially outwardly projecting tab  22 . A magnetic read/write head or slider  26  is provided on the underside of the suspension  21 . If the arm  14  is pivoted counterclockwise in the direction of the arrow  18  from the position shown in  FIG. 1 , the head  26  moves to a position in which it is closely adjacent the magnetic surface on the disk  12 . Limited pivotal movement of the arm  14  in the directions of arrows  18  and  19  causes the head  26  to move along a path which extends approximately radially of the rotating disk  12 , within a zone where the head remains closely adjacent the magnetic surface on the disk  12 . In this operational mode, the magnetic head  26  can be used to electromagnetically write information to or read information from the magnetic surface on the disk  12 , in a manner which is known in the art. 
     A stationary support  41  is provided near a peripheral edge of the disk  12 . A ramp surface  42  is provided on the support  41 , and includes several surface portions  46 – 53 . In particular, in a direction from the surface portion  46  to the surface portion  53 , the ramp surface  42  includes an upwardly inclined surface portion  46 , a raised surface portion  47 , a downwardly inclined surface portion  48 , a lower surface portion  49 , an upwardly inclined surface portion  50 , a raised surface portion  51 , a downwardly inclined surface portion  52 , and a lower surface portion  53 . A projection  55  is fixedly coupled to and projects horizontally outwardly from the support  41 , at a location which is aligned with the raised surface portion  47 . A pad  56  of a velvet material is provided on an upwardly facing surface of the projection  55 . 
     A head cleaning mechanism in the disk drive  10  includes a rigid bar  61  which is fixedly secured to and projects horizontally outwardly from the support  41 . A resilient flexible element  62  has one end fixedly secured to the outer end of the rigid bar  61 , and has its other end fixedly secured to one end of a further rigid bar  63 . The rigid bar  63  is oriented so that it is approximately perpendicular to the flexible element  62 . A short cylindrical rod is secured to the outer end of the bar  63 , so as to define a ridge or lip  64 . A damping part  68  is fixedly secured to the flexible element  62  along most of the length thereof. In the disclosed embodiment, the damping part  68  is made of a viscoelastic polymer, and is fixedly bonded to the flexible element  62 . However, the damping part  68  could alternatively be made of some other type of material. The damping part  68  is configured so that, if the element  62  is flexed, the resilience of element  62  and the damping effect of part  68  will cooperate to return the element  62  relatively slowly to its original position, without oscillation. 
     A textured cleaning pad  69  is fixedly secured to the rigid bar  63 , at an end thereof nearest the flexible element  62 . The cleaning pad  69  has an upwardly facing surface which is made of a textured ceramic material, a textured polymer, or a textured glass material. One suitable textured glass material is commercially available from Physical Optics Corporation of Torrance, Calif. as a 5° Sol-gel Holographic White Light Shaping Diffuser (LSD). As is known in the art, sol-gel is composed of silica suspended in a polymeric matrix. Heat treatment or hard ultraviolet exposure drives off most of the organic component, leaving a hard, glassy surface. Embossing of sol-gel is carried out under high pressure, and can produce features with heights up to several microns. 
     As an alternative, the textured surface could be created by chemically etching a glass material. The chemical etching can be carried out using solutions of various etchants, such as hydrofluoric acid and/or an etchant commercially available under the tradename ETCHALL from B &amp; B Etching Products, Inc. of Sun City, Ariz. 
     With reference to  FIG. 1 , assume that the arm  14  is currently in a position in which it has been pivoted counterclockwise in the direction of arrow  18  from the position shown in  FIG. 1 , so that the head  26  is spaced from the ramp  42  and is closely adjacent the magnetic surface on the disk  12 . Assume that the arm  14  is then rotated clockwise in the direction of arrow  19 . During this pivotal movement of the arm  14 , the tab  22  will engage and slide up the inclined surface portion  46 , causing the suspension  21  and head  26  to be lifted upwardly, so that the head  26  moves away from the disk  12 . The tab  22  will then slide across the raised surface portion  47 . As this occurs, the lower side of the head  26  will slide across the velvet pad  56 , and the velvet pad  56  will remove at least some of the contaminants that may be building up on the head  26 , in order to help keep the head  26  clean. While the head  26  is engaging the velvet pad  56 , the tab  22  may be lifted off the raised surface portion  47 . 
     As the arm  14  continues to rotate, the tab  22  will slide down the inclined surface portion  48 , until it is adjacent or engaging the lower surface portion  49 . Pivotal movement of the arm  14  is normally stopped at this position, which is the position shown in  FIG. 1 , and which is commonly referred to as the park position of the head  26  and arm  14 . The lower surface portion  49  and the two inclined surface portions  48  and  50  on either side of it collectively form a detent, and this detent tends to maintain the head  26  and arm  14  in the park position. In the park position, the head  26  is spaced from the disk  12 , so that a mechanical shock will not cause the head  26  and disk  12  to forcibly engage each other in a manner that could cause physical damage to one or both. 
     At a subsequent point in time, the arm  14  can be rotated in the direction of arrow  18 , and the sequence of events just described will occur in a reverse order. In particular, the tab  22  will slide up the inclined surface portion  48 , across the raised surface portion  47 , and down the inclined surface portion  46 , so that the head  26  is again positioned adjacent to the rotating disk  12 . As this occurs, and in particular as the tab  22  slides back across the raised surface portion  47 , the head  26  will slide back across the velvet pad  56 , thereby giving the pad  56  another opportunity to remove contaminants and thereby keep the head  26  clean. 
     Although the velvet pad  56  is very helpful in removing contaminants from the head  26 , from time to time a more effective cleaning operation may be needed. In the disclosed embodiment, this is carried out in the following manner. Assuming that the head  26  and arm  14  have been moved to the park position of  FIG. 1 , the arm  14  is rotated clockwise in the direction of arrow  19 , into a zone of movement where the further cleaning operation can be carried out on the head  26 . As the arm  14  is rotated clockwise, the tab  22  to slides up the inclined surface portion  50  and across the raised surface portion  51 , and then slides down the inclined surface portion  52  until it is disposed over the lower surface portion  53 . As the tab slides down the inclined surface portion  52 , the head  26  will be lowered into contact with the textured surface of the cleaning pad  69 . As a result, the pad  22  does not actually move into engagement with the lower surface portion  53 , but instead ends up being spaced slightly from it. As the arm  14  is carrying out this rotation in the direction of arrow  19 , the arm  14  engages the lip  64  and moves the rigid bar  63 , which causes the flexible element  62  to be resiliently flexed against the resistance of the damping part  68 . This flexing of the resilient element  62  causes the cleaning pad  69  to be displaced in a direction approximately radially of the pivot axis for the arm  14 . Next, two different forms of movement occur at the same time. 
     First, the arm  14  is rotated back in the direction of arrow  18  to a position in which the tab  22  is still over the lower surface portion  53  and the head  26  is approximately centered over the pad  69 . The actuator controlling the arm  14  is then used to reciprocate the arm  14  several times in the directions of arrows  18  and  19 , so as to thereby reciprocate the head  26  several times in relation to the pad  69  which it engages. Simultaneously, and since the damping part  68  limits the speed with which the flexible element  62  can return to its original position under its own resilience, the arm  14  moves out of engagement with the lip  64 . The resilience of the flexible element  62  will slowly and progressively return the flexible element  62  to its original position against the damping effect of the damping part  68 . As this occurs, the cleaning pad  69  moves relative to the head  26  in a direction approximately radially of the pivot  16 , or in other words in a direction approximately perpendicular to the directions in which the head  26  is being reciprocated by the arm  14 . 
     As these two independent components of movement are occurring, the textured surface of the cleaning pad  69  rubs against the head  26 , and scrapes away contaminants that the velvet pad  56  was not able to remove. When the flexible element  62  eventually reaches its original position, such that the cleaning pad  69  is also in its original position, the arm  14  is pivoted in the direction of the arrow  18  until it reaches the park position shown in  FIG. 1 . As this occurs, the tab  22  slides up the inclined surface portion  52 , across the raised surface portion  51 , and down the inclined surface portion  50 . 
     The flexible element  62  and the damping part  68  effectively form an over-damped harmonic oscillator, which movably supports the cleaning pad  69 . This relationship is shown diagrammatically in  FIG. 2 . In particular, engagement of the arm  14  with the lip  64  ( FIG. 1 ) causes a load force  81  ( FIG. 2 ) to be applied to the cleaning pad  69 , thereby resiliently flexing the flexible element  62  against the resistance of the damping part  68 . The load force  81  is then removed, and energy stored in the flexible element  62  returns the cleaning pad  69  to its original position, while the damping part  68  dissipates much of the energy stored in the flexible element. This over-damped arrangement permits precise control of the velocity and displacement of the cleaning pad. 
       FIG. 3  is a diagrammatic view of the head  26  when it is engaging the textured cleaning pad  69 . When the arm  14  reciprocates the head  26  in the direction of arrows  18  and  19  in  FIG. 1 , the head is reciprocated relative to the cleaning pad  69 . Consequently, asperities of the cleaning surface on the pad  69  each move reciprocally in relation to the head  26 , as indicated diagrammatically for one asperity by a double-headed arrow in  FIG. 3 . The asperities thus effectively trace lines on the head  26 , as shown diagrammatically by the lines depicted on the head  26  in  FIG. 4 . If the head  26  is reciprocated or oscillated with an amplitude greater then half its width, some of the asperities should trace lines across the entire width of the head. The maximum distance  86  between these trace lines is indicated at  86  in  FIG. 4 , and represents the minimum distance that the cleaning pad needs to move during a head cleaning operation in order to ensure that the entire operational surface of the head  26  is subjected to a cleaning effect. The width of each line on the head  26  in  FIG. 4  represents the diameter of the contact area between an asperity and the head  26 , or in other words the width effectively cleaned by a single asperity during one stroke of the reciprocal movement. Using this diameter and the frequency at which the head is reciprocated, the maximum allowable velocity of the cleaning pad during the cleaning operation can be calculated. 
     In order to empirically evaluate this, a thin layer of gold was sputtered onto the bottom surface of the head  26  of  FIG. 1 , and  FIG. 5  is a view of the head  26  with the thin layer of gold thereon. A single cleaning operation was then carried out using apparatus of  FIG. 1 , in the manner described above.  FIG. 6  is a view of the head  26  after this cleaning operation, and shows scratches in the gold which represent paths traced by asperities of the cleaning pad  69 . 
     The distance between the scratches was measured to determine a maximum effective asperity-to-asperity spacing of D a-a =60 μm. The width of the scratches was measured to determine an asperity contact diameter value Φ a =5 μm. Note that D a-a  will depend on factors such as the cleaning pad texture, the air bearing surface (ABS) and shallow step geometry, and the amplitude of reciprocation. With D a-a  and Φ a  known, and given a frequency of head reciprocation f, a necessary distance of cleaning pad motion ΔX during a head scrub and a maximum pad velocity dx/dt max  can be specified as:
 
 ΔX&gt;D   a-a 
 
 dx/dt   max &lt;2 fΦ   a 
 
       FIG. 7  is a graph showing two curves which respectively represent the displacements during a cleaning cycle of the cleaning pad  69  (upper curve) and the head  26  (lower curve). In  FIG. 7 , time segment  111  corresponds to the movement of the arm  14  of  FIG. 1  which effects flexing of the flexible element  62 . Time segment  112  corresponds to the movement of arm  14  which positions the head  26  at a selected scrub location on the pad  69 . Time segment  113  represents the actual cleaning operation, which has a duration ΔT corresponding to the time needed for the flexible element  62  to move the cleaning pad  69  through a distance ΔX against the damping effect of the damping part  68 . Time segment  114  corresponds to the movement of arm  14  and head  26  from the scrub location back to the park position of  FIG. 1  at the end of the cleaning operation. 
     In the embodiment of  FIG. 1 , and as discussed above, the damping part  68  is configured so that the flexible element  62  returns to its original position without oscillation. As an alternative, the damping element could be omitted, or configured to effect a lesser degree of damping, so that the flexible element  62  experiences some degree of resonant oscillation as it returns to its original position after being flexed. As a result, the cleaning pad  69  would be reciprocated or oscillated by the flexible element  62  in relation to the head  26  at the same time that the head  26  is being reciprocated or oscillated by the arm  14  relative to the cleaning pad  69 , where these two different reciprocating movements occur in directions that are generally perpendicular to each other. 
       FIG. 8  is a diagrammatic perspective view of an apparatus in the form of a head cleaning mechanism  210 , which is an alternative embodiment of the head cleaning mechanism in the disk drive  10  of  FIG. 1 .  FIG. 9  is a diagrammatic perspective exploded view of the head cleaning mechanism  210  of  FIG. 8 . The head cleaning mechanism  210  includes a base  212 , which is made of a durable plastic but could alternatively be made of any other suitable material. The base  212  has an outwardly projecting arm  216 , and the arm  216  has thereon a ramp surface  217 , which is similar in structure and function to the ramp surface shown at  42  in  FIG. 1 . 
     The arm  216  also has a boss  218  that serves as a limiter. When the arm  14  and head  26  ( FIG. 1 ) are disposed in their park position, the suspension  21  for the head  26  is aligned with the limiter  218 . In the event of a mechanical shock, for example if the disk drive is dropped, the limiter  218  engages a portion of the head suspension  21 , in a manner that protects the head  26  from damage. Further, in embodiments where the suspension  21  supports several heads  26  the arm  14 , the cooperation between the limiter  218  and the suspension  21  helps prevent the heads from hitting each other and sustaining damage. 
     As best seen in  FIG. 9 , the base  212  has an upwardly projecting cylindrical pivot axle  221 , and has two upwardly projecting cylindrical stops  222  and  223 , which are each spaced radially outwardly from the pivot axle  221 . A spring catch  226  is provided on the base  212  at a location which is spaced radially outwardly in a different direction from the pivot axle  221 . The base  212  also has an upwardly extending projection  227 . A threaded hole  228  extends vertically downwardly into the projection  227  from the center of the top surface thereof. Two short cylindrical studs  231  and  232  each project upwardly from the top surface of the projection  227 , on opposite sides of the threaded hole  228 . 
     A coil spring  236  encircles the pivot axle  221 , and has two outwardly projecting legs  237  and  238 . The leg  237  engages the spring catch  226 . The spring  236  is made of metal, but could alternatively be made from some other suitable material. 
     A pivot lever  241  has an approximately circular hub  242 , and has two arms  243  and  244  projecting horizontally outwardly from the hub  242  in respective directions which are approximately radial, and which are approximately perpendicular to each other. The hub  242  has a central opening  246  extending vertically through it, and this opening  246  rotatably receives the pivot axle  221 . In the embodiment of  FIGS. 8-9 , the lever is made of a durable plastic, but it could alternatively be made of any other suitable material. 
     The hub  242  has in the underside thereof an annular recess which is not visible in the drawings, and which receives the coil of the spring  236 . The hub  242  has through one side wall thereof a vertical slot  247 , through which the leg  237  of the spring  236  extends outwardly to the spring catch  226 . The leg  243  of the lever  241  has a further spring catch  248 , which cooperates with the leg  238  of the spring  236 . The spring  236  urges the lever  241  to pivot clockwise in  FIGS. 8–9 . The stop  223  engages the arm  243  in order to limit clockwise pivotal movement of the lever  241  under the urging of the spring  236 . The stop  222  engages the arm  244  in order to limit counterclockwise pivotal movement of the lever  241 . 
     The hub  242  has a planar circular surface  249  on the upper side thereof, for a purpose which is discussed later. A ridge or lip  251  is provided at the outer end of the arm  243 . When the arm  14  and head  26  ( FIG. 1 ) are moved past their park position, the arm  14  engages the ridge or lip  251 , and pivots the lever  241  counterclockwise against the urging of the spring  236 . 
     A rectangular cleaning pad  253  is fixedly secured in any suitable manner to the arm  244  of the pivot lever  241 , for example through use of a known epoxy adhesive. In the disclosed embodiment, the cleaning pad  253  is a light shaping diffuser part obtained commercially under catalog number LSD10/10PC30-2 from Physical Optics Corporation of Torrance, Calif. Although this particular part is commercially marketed as an optical component, it is used here for its mechanical structure and not its optical characteristics. 
     More specifically, the cleaning pad  253  has a center substrate made from a polycarbonate material or an acrylic material, and has an ultraviolet curing epoxy spread on each of the top and bottom surfaces of the substrate. Before the epoxy is cured, it is embossed with a desired texture (such as a 10° diffusion pattern), and then is cured using ultraviolet light. Although the embodiment of  FIGS. 8–9  uses this particular structural part, it would alternatively be possible to use some other suitable part. The cleaning pad  253  has on the top side thereof an upwardly-facing cleaning surface  254 , which is functionally comparable to the cleaning surface provided on top of the cleaning pad  69  in the embodiment of  FIG. 1 . 
     A disk-like damping part  261  is disposed concentrically above the pivot axle  221 , and cooperates with the upwardly-facing surface  249  on the hub  242 . A metal retaining plate  266  has an approximately circular portion  267  that cooperates with the top of the damping part  261 , and has a further portion with three holes  271 – 273  that engages the top of the projection  227 . The holes  271  and  273  respectively receive the studs  231  and  232  on the projection  227 , and the opening  272  is aligned with the threaded hole  228  in the projection  227 . A screw or bolt  276  fixedly secures the retaining plate  266  to the projection  227 . In particular, the bolt  276  has a head which engages the top surface of the plate  166 , and has a threaded shank which extends through the opening  272  and threadly engages the threaded hole  228 . 
     The damping part  261  has alternating layers of a polyester material and a pressure sensitive adhesive. In the embodiment of  FIGS. 8–9 , the pressure sensitive adhesive is obtained commercially under catalog number ECA-172 from Entrotech, Inc. of Columbus, Ohio. However, it would alternatively be possible to use any other suitable material. The top and bottom surfaces of the damping part  261  are layers of the pressure sensitive adhesive, and respectively engage the underside of the portion  267  of the retaining plate  266 , and the top surface  249  on the hub  242  of lever  241 . The damping part  261  yieldably resists pivotal movement of the lever  241  with respect to the retaining plate  266 . This resistance is due primarily to the fact that pivotal movement of the lever  241  causes shear forces within the pressure sensitive adhesive layers, and the pressure sensitive adhesive yieldably resists internal movement that relieves these shear forces. 
     The cleaning mechanism  210  of  FIGS. 8 and 9  operates in a manner which is similar to the operation of the cleaning mechanism in the embodiment of  FIG. 1 , and its operation is therefore described only briefly here. In particular, when the read/write head  26  and its support arm  14  ( FIG. 1 ) are pivoted beyond their park position, the support arm  14  engages the ridge or lip  251  on the lever arm  243 , and pivots the lever  241  counterclockwise against the force of spring  236  and the resistance of damping part  261 . The arm  14  then returns to a position in which the head  26  is in contact with the surface  254  on the cleaning pad  253 , and the arm  14  then oscillates the head  26  several times. As this occurs, the spring  236  is slowly returning the lever  241  to its original position, while the damping part  261  yieldably resists this pivotal movement, so that this pivotal movement occurs more slowly than would otherwise be the case. After the arm  14  has oscillated the head  26  on the cleaning surface  254 , the arm  14  returns the head  26  to its park position, while the lever  241  is still being returned to its original position by the spring  236 . 
     The present invention provides a number of advantages. One such advantage is realized where cleaning of the head occurs by placing the head in engagement with a cleaning part and by then effecting relative movement of the head and cleaning part in a manner which includes a component of movement that is representative of an applied force subject to a damping influence. In one particular configuration, the applied force includes a harmonic oscillation, and the damping influence includes overdamping of the harmonic oscillation. This damped-force approach permits precise control over both the velocity and displacement of the cleaning part. A related advantage is that, through effective cleaning of the head with this technique, it becomes practical to implement a relatively high storage density on a hard disk of a removable cartridge, even where the read/write head is in the drive, and without a significant need to seal the cartridge. 
     Although a selected embodiment has been illustrated and described in detail, it will be understood that various substitutions and alterations can be made therein without departing from the spirit and scope of the present invention, as defined by the following claims.