WO1993019460A1 - Carriage retention device for disk drives - Google Patents

Carriage retention device for disk drives Download PDF

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Publication number
WO1993019460A1
WO1993019460A1 PCT/US1993/002743 US9302743W WO9319460A1 WO 1993019460 A1 WO1993019460 A1 WO 1993019460A1 US 9302743 W US9302743 W US 9302743W WO 9319460 A1 WO9319460 A1 WO 9319460A1
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WO
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Application
Patent type
Prior art keywords
carriage
head
position
disk
coil
Prior art date
Application number
PCT/US1993/002743
Other languages
French (fr)
Inventor
Bruce A. Mcfadden
Original Assignee
Digital Equipment Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

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Classifications

    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B21/00Head arrangements not specific to the method of recording or reproducing
    • G11B21/16Supporting the heads; Supporting the sockets for plug-in heads
    • G11B21/22Supporting the heads; Supporting the sockets for plug-in heads while the head is out of operative position
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B25/00Apparatus characterised by the shape of record carrier employed but not specific to the method of recording or reproducing, e.g. dictating apparatus; Combinations of such apparatus
    • G11B25/04Apparatus characterised by the shape of record carrier employed but not specific to the method of recording or reproducing, e.g. dictating apparatus; Combinations of such apparatus using flat record carriers, e.g. disc, card
    • G11B25/043Apparatus characterised by the shape of record carrier employed but not specific to the method of recording or reproducing, e.g. dictating apparatus; Combinations of such apparatus using flat record carriers, e.g. disc, card using rotating discs

Abstract

A carriage retention device for use in a head disk assembly of a disk drive which reads or writes data to or from a disk with a head. The disk has a landing area where the head rests when not in use. The carriage supports the head and positions it relative to the disk. The carriage is movable to position the head over the data tracks of the disk and in the head landing area. A coil mounted on the carriage is used in conjunction with a stationary magnet assembly adjacent to the coil to electromagnetically position the carriage. The magnet assembly produces a non-uniform magnetic field having a region with a low gradient of flux density and a region with a higher gradient of flux density. A ferrous metal body, such as a steel ball, is mounted on the carriage so that it is positioned within the region with the low gradient of flux density when the carriage positions the head over the data track of the disk and within the region with the higher gradient of flux density when the head carriage positions the landing area. The magnet assembly exerts force on the ferrous metal body sufficient to move the carriage toward the parked position when no current flows in the coil and to hold the carriage in the parked position during spin up or when the head disk assembly is being moved.

Description

CARRIAGE RETENTION DEVICE FOR DISK DRIVES

Field of the Invention

The present invention relates to a carriage retention device for use in a disk drive and, in particular, to a magnetic retention device for use in a head disk assembly of a disk drive which holds the carriage in a parked position with the heads in a landing zone during spin up o movement of the head disk assembly and which returns the carriage to a parked position with the heads in a landing zone during spin down.

Background of the Invention

A head disk assembly is part of a disk drive and typically includes a plurality of disks, either magnetic o optical, arranged in a stacked relationship upon a spindle A motor is connected to the spindle for rotating the stacked disk assembly at high speed. A positioner assembl is mounted adjacent to the stacked disk assembly. The positioner has a plurality of access arms, each one extending over one of the surfaces of the stacked disks. At least one head assembly is mounted at the end of each access arm. In a rotary positioner, the access arms and a coil holder are parts of the same rigid body which rotates about a pivot. This movable body including the coil holder and the access arms is typically referred to as the carriage. A magnet assembly comprising a permanent magnet and adjacent pole pieces is mounted in a stationary position relative to the movable carriage. A coil of wire is held by the coil holder in the uniform magnetic field of the magnet assembly. The coil and magnet assembly are typically referred to as the actuator. A current passing through the coil creates a force proportional to the current, as is well known. This force causes the movable or rotatable portion of the positioner assembly to pivot, which swings the access arms in an arc over the disks to precisely position the heads or read/write operations. The structure and operation of a linear positioner is well known and such a linear positioner can be used in place of the rotary positioner discussed above. The linear positioner moves the access arms over a radius of the disks.

In operation, when the disks rotate at high speed, th air movement causes the heads mounted on the access arms t lift off and fly above the respective disk sur aces. As long as the disks continue to rotate, the heads remain flying and separated from the disk surface by a very small distance, typically, 250 millionths of mm (10 millionths o an inch) . If the motor is not driving the spindle causing the disks to rotate and the carriage is in a parked position, the heads rest upon a specific area of the disk surface not used for data and typically referred to as a landing zone or area. If one of the heads abruptly contacts the disk surface, severe damage can be done to th head or the disk surface.

During shipping or movement of the head disk assembly the carriage must be in the parked position so that the heads are in the landing area. Jarring or bumping the hea disk assembly can cause the carriage to move bringing the heads into contact with the data area of the disk causing damage to the disk surface. Therefore, the carriage must be held in the parked position during movement of the head disk assembly to assure that the heads remain in the landing area.

In known carriage retention devices when the power to the actuator is turned off while the heads are over the data surface of the disk, a separate circuit is used to control the carriage returning it to the parked position and landing the heads in the designated landing area. In order to push the carriage to the park position, the back emf of the spindle motor is routed to specially designed circuitry and through the actuator coil . The special circuitry adds cost to the overall drive and takes up space, which is at a premium as disk drives become smaller

In order to hold the carriage in the parked position during movement of the head disk assembly and during spin up known carriage retention arrangements have a magnet embedded into the crashstop of the assembly and a piece of ferrous metal attached to the carriage. The carriage contacts the crashstop when the carriage is- moved to the park position. Even though the magnet is* physically separated from the ferrous metal by a portion of the wall of the crashstop, since the magnet is embedded into the crashstop structure, the magnet attracts the ferrous meta attached to the carriage holding the carriage against the crashstop. There are several disadvantageous aspects of these arrangements. First, the ferrous metal piece attached to the carriage physically contacts the crashsto structure each time the carriage is moved to the park position. This repeated physical contact causes a deterioration and ultimate failure of the joint between t carriage and the piece of ferrous metal. If the piece of ferrous metal becomes deattached from the carriage, the retention mechanism- is ruined and repair is required. Second, the design of the crashstop is compromised becaus the crashstop can withstand less compressive force from t carriage since the wall thickness of the crashstop betwee the embedded magnet and crashstop surface must be maintained quite thin. If the wall thickness of the crashstop is increased to a thickness which withstands the repeated compressive force of the collision between the carriage and the crashstop, the size of the magnet must be substantially increased to provide sufficient magnetic attraction to hold the carriage in place. If a large magnet is used, the overall size of the crashstop must be increased to accommodate the magnet, which complicates the design of the crashstops in addition to using more space i the assembly.

Summary of the Invention

The invention in its broad form resides in a carriage retention device for a disk drive generally as recited in claim 1. Described hereinafter by way of example is a carriage retention device for use in a head disk assembly of a disk drive that both holds the carriage in the parked position against a crashstop during spin up of the head disk assembly or during movement of the head disk assembly and also returns the carriage to the parked position if power is removed from the assembly while the heads are ove the data portion of the disk and holds the carriage in the parked position during spin down. The invention eliminate the need to attach magnets or other material to the crashstop or embed them therein. Indeed, no alterations o changes of any kind are required for the crashstop structure. Accordingly, the design of the crashstop is not compromised or made more complicated. In addition, no circuitry or software is needed to return the carriage to the parked position if power is removed while the heads are positioned over the data portion of the disk.

A small cavity is made in the carriage of a rotary positioner assembly of a head disk assembly and a small ferrous metal object, a ball in the preferred embodiment, is secured within the cavity by an adhesive or other suitable material. Of course, the small ferrous metal body can be any geometric shape. The ferrous metal ball is positioned in the carriage so that the ball is in a region of a low gradient of flux density in the non-uniform magnetic field of the actuator magnet when the carriage is rotated to position the heads over the data portion of the disk. In this position, only a slight magnetic force is exerted upon the ball urging it toward the crashstop. This force is insufficient to interfere with the normal positioning of the heads over selected data tracks on the surface of the disks. As the carriage rotates to position the heads over the landing area on the surface of the disks, the magnetized ball moves to a point of higher gradient of flux density in the non—uniform magnetic field of the actuator magnet and the magnetic force exerted on the ball is increased. Again, this force is insufficient to interfere with the normal positioning of the heads.

However, if power is removed from the head disk assembly when the carriage is positioning the access arms to place the heads over the data portion of the disk, the force exerted upon the ferrous metal ball is sufficient to move the carriage toward the landing zone. The ferrous metal ball is located in the carriage so that when the carriage is adjacent to the crashstop and the heads are in the landing zone, the ferrous metal ball is positioned in higher gradient of flux density in the non-uniform magneti field of the actuator magnet and this force is sufficient to hold the carriage against the crashstop. Since the force is sufficient to hold the carriage against the crashstop, the heads remain in the landing area even if th head disk assembly is moved or jarred. The force is also sufficient to hold the carriage against the crashstop during spin up of the head disk assembly even though the drag of the air against the heads and the friction between the heads and the landing surface of the disk together wit the moment attributable to length of the access arms tends to rotate the carriage which would prematurely cause the heads to wander over the data portion of the surface of th disks. This force holds the carriage against the crashsto δ until current is passed through the coil during a normal seek operation.

Brief Description of the Drawings

A more detailed understanding of the invention may be had from the following detailed description of an exemplar preferred embodiment and upon reference to the accompanyin drawings, in which:

Fig. 1 is a general illustration of a head disk assembly of a disk drive.

Fig. 2 is a top view of the head disk assembly showin an access arm of the positioner assembly positioning a hea over the data portion of a disk.

Fig. 3 is a partial cross section view taken along lines A-A of Fig. 2 showing the relative position of the actuator magnet and the ferrous metal ball embedded in the carriage of the positioner assembly when the positioner places the data heads over the data portion of the disks.

Fig. 4 is a top view of the head disk assembly showi an access arm of the positioner assembly in the park position with a head in the landing zone. Fig. 5 is a partial cross sectional view taken along line B-B of Fig. 4 showing the relative position of the actuator magnet and the ferrous metal ball embedded in the carriage of the positioner assembly when the positioner is in the parked position with the heads in the landing zone.

Fig. 6 is a representation of a portion of the actuator assembly and the magnetic field through which the ferrous metal ball moves. Fig. 7 is a graphical representation of the flux density along the reference line shown in Fig. 6.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. On the contrary, the applicant's intention is to cover all modifications, equivalents, and alternatives falling withi the spirit and scope of the invention as defined by the appended claims. Detailed Description of a Preferred Embodiment

Referring to the drawings, wherein the reference characters designate like or corresponding parts througho the views, Fig. 1 is a general illustration of a head dis assembly 10 for use in a disk drive with many of the structural parts removed or simplified for the purposes o clarity. A housing 12 contains a plurality of disks 14 mounted in stacked relation on a spindle 16. Any number disks 14 can be used to satisfy design criterion and storage capacity requirements. A motor 10 is connected a a direct drive with the spindle 16 forming the motor shaf Of course the motor could be an indirect drive connected the spindle.16 by belts or other suitable means. A positioner assembly 20 is mounted adjacent to the disks 1 At least one head assembly 22 (hereinafter referred to simply as a head) is mounted to each access arm of the positioner assembly 20. The heads 22 are moved back and forth over the surface of the disks 14 under the control the positioner assembly 20. As is well known to those of ordinary skill in the field, the positioner assembly 20 aligns the heads 22 over specific data tracks or cylinder for read/write operations. The motor 18 drives the spind 16 causing the disks 14 to rotate at high speed in the direction of rotation (D.O.R.) shown by the arrow. The a currents generated by the rotating disks 14 cause the hea 22 to fly on a cushion of compressed air over the surface of the disks 14.

Fig. 2 is a top view of the head disk assembly 10 wit the top of the housing 12 removed for clarity. The rotary positioner assembly 20 is adjacent to the disk 14. The access arm 24 holds the head 22 over the data track at the outside diameter of the disk 14. Of course, as illustrate in Fig. 1, it is contemplated that the head disk assembly 10 includes a plurality of access arms 24 and heads 22, while only one combination is seen is Fig. 2. However, it will be appreciated by those of ordinary skill in the fiel that the present invention can also be used in a head dis assembly having only a single disk. Thus, the number of disks in the head disk assembly is a matter of design choice and storage capacity requirements. The access arm 24 is connected to a pivot 26 and rotates about the pivot 26 to move the head 22 in an arc over the surface of the disk 14. A coil holder 28 has two arms 30a and 30b formi a general "V" shape. The coil holder 28 is connected for rotation about the pivot 26. The access arm 24 and the coil holder 28 form a rigid member and rotate in unison a are commonly referred to as a carriage. A coil 32 is connected between the arms 30a and 30b of coil holder 28 and, of course, moves with the coil holder 28. A base plate or bottom pole 34 is mounted to the bottom of the housing 12. A ferrous metal body 36, in the preferred embodiment a ball, is embedded in arm 30b of coil holder 28. Of course, the ferrous metal object or body 36 can be any other geometric shape. In the preferred embodiment, a small cavity is made in the coil holder 28 and a 1.5mm

(.062 inch) diameter steel ball is placed in the cavity an held by an adhesive or other suitable means. The size and material of the ferrous metal object are matters of design choice. In this preferred embodiment, no additional space is needed within the positioner assembly 20 since the ball 36 substantially fills the cavity in the coil holder 28. However, it will be appreciated by those of ordinary skill in the field that, as an alternative embodiment, the ferrous metal body 36 can be attached to the coil holder 2 by other procedures. Indeed, if space within the head dis assembly is not a concern, the ferrous metal body 36 can b connected to the surface of the coil holder 28. The location of the ferrous metal ball 36 in arm 30b is described in greater detail below. A permanent magnet 38 is fixedly mounted to the base 34 and is positioned below the coil 32. A plate or top pole 40 having the same general shape as the base 34 is placed over the carriage and is shown partially cut away for the sake of clarity. As is well known, passing a current through coil 32 create a force proportional to the current which causes the carriage to rotate about the axis of the pivot 26. Of course, the access arm 24 carrying head 22, coil holder 28 including the embedded ball 36 and the coil 32 rotate in unison while the base 34, plate 40 and the permanent magne 38 remain fixed. The coil 32, the base 34, the plate 40 and the permanent magnet 38 are typically referred to as a actuator. The coil holder 28 moves between the crashstops 42a and 42b in response to the force created by the curren passing through the coil 32.

In the position illustrated in Fig. 2, the coil hold

28 is adjacent the crashstop 42b. Crashstops 42a and 42b can be of any design well known in the art. As the curre to the coil 32 is varied, the position of carriage moves between the crashstops 42a and 42b to position the head 2 over an appropriate data track on the surface of the disk 14.

Fig. 3 is a cross sectional view taken along line A- of Fig. 2 when the positioner assembly 20 has the head 22 located over the data track at the outside diameter of th surface of disk 14. The ferrous magnetic ball 36 is farthest away from the magnet 38, but within a region having a low gradient of flux density in the non-uniform magnetic field of the actuator magnet 38. A ferrous body in a non-uniform magnetic field experiences a force that moves it to a point having a higher gradient of flux density in the magnetic field. The ferrous ball 36 become magnetized in the field of' magnet 38. Different parts of the ferrous ball 36 are magnetized in different amounts an are exposed to different field strengths . The sur ace of the ball 36 possesses a distributed surface force because of electromagnetic stresses residing on the surface of the ball. The non-uniformity of the field causes the sum of the stresses multiplied by the elemental areas of the ball not to equal zero and, as a result, the ball has a resultant force acting upon it. This principle of magnetism is discussed in detail in Magneto-Solid Mechanic by Francis C. Moon published by John Weley & Sons, 1984 pp 37-61 which is incorporated herein by reference. The for on the ball is proportional to the gradient of flux densi in the non-uniform magnetic field.

Fig. 6 is an illustration of the uniform and the non uniform magnetic fields caused by the permanent magnet 44 and pole pieces 46 and 48. Three points a, b, and c in t field are plotted in Fig. 7 which has Flux Density along the y-axis and location along the x-axis. Point a is in the non-uniform magnetic field but the gradient of flux density is low. Point b is also in the non-uniform magnetic field but at a much higher gradient of flux density compared to point a. Point c is in the uniform magnetic filed of the magnet. The force acting upon the ferrous metal ball 36 show in Figs. 2 and 3 is low since the ball is essentially at location equivalent to point a in Fig. 6. The force exerted on the ferrous metal ball 36 in the position show in Figs. 2 and 3 is insufficient to affect the positionin of the heads during normal operations. As current is supplied to the coil 32 and the access arm 24 rotates abo the pivot 26 thereby moving the head 22 to a new data tra location, the coil holder 28 also rotates toward crashsto 42a. This movement causes the ferrous metal ball 36 to move toward the edge of magnet 38 and a point having a higher gradient of magnetic flux density. The ball 36 is moving along a line equivalent to that shown in Fig. 6. the carriage moves all the way to crashstop 42a as shown Fig. 4, the access arm 24 rotates moving head 22 over the landing zone on the surface of disk 14. In this position the ferrous metal ball 36 is substantially at the edge of the magnet 38 as shown in Fig. 5. Thus, the ball 36 is i a region having a higher gradient flux density compared t the gradient of flux density when the carriage positions the heads over the data tracks of disk 14. The position the carriage 34 adjacent crashstop 42a is equivalent to * positioning ball 36 at point b in Fig. 6. The resultant force on the ferrous metal ball 36 in this position is sufficient to hold the carriage against crashstop 42a whe no current is applied to coil 32. When the access arm 24 is in the position as shown in Fig. 2 and power to the head disk assembly is turned off for any reason the positioner assembly 20 must pivot to return the head 22 to the landing zone to avoid contact with the data area of the surface of the disk 14 and for ther operating reasons well known to those of ordinary skill in the field. The force exerted upon the ferrous metal ball 36 is small but sufficient to move the coil holder 28 towards crashstop 42a. As the coil holder 28 is moving, the ferrous metal ball 36 is also moving toward a region of a higher gradient of flux density and, hence, t force on the ferrous metal ball 36 increases. When the carriage is. against the crashstop 42a the ferrous metal ball 36 is at a point of high gradient of flux density an the force on ferrous metal ball 36 holds the carriage 34 against crashstop 42a. Thus, the positioning of the ferrous metal ball 36 in the coil holder 28 at a location that places the ferrous metal ball 36 in a region having low gradient of flux density in the non-uniform magnetic field of the actuator magnet 38 (when the access arm 24 h the head 22 over the data portion of the surface of disk 14) and in a region having a higher gradient of flux density when the access arm 24 has the head in the landin zone of the disk 14, provides the carriage return and locking functions for the head disk assembly of the disk drive. The ferrous metal ball 36 can be placed closer to the distal end of the arm 30b of the coil holder 28 to increase the moment arm (i.e., the distance from the location of the ferrous metal ball 36 to the pivot 26) and accordingly, exert a greater force holding the carriage against the crashstop 42a. The exact location of the ferrous metal ball 36 is a matter of design choice provide the above special relationships are maintained between the position of the ferrous metal ball 36 and the magnet 38 in the non-uniform magnetic field.

During spin up, the air drag on the heads 22 and the head 22 to disk 14 friction creates a force that tends to rotate the access arms 24 over the data portion of the dis 14 due to the length of the moment arm between the heads 2 and the pivot 26. Under these conditions, even though no current is passing through coil 32, the access arms 24 can rotate, causing the heads 22 to undesirably wander over th data portion of the disk 1 . When the carriage is positioned against the crashstop 42a as shown in Fig. 4 th force exerted on the ferrous metal ball 36 is sufficient t hold the carriage in place even during spin up of the disk 14. When the head disk assembly 10 is to be moved, the carriage is positioned as shown in Fig. 4 so that the head 22 are resting in the landing area on the surface of disk 14. The force exerted on the ferrous metal ball 36 is sufficient to hold the carriage against crashstop 42a even if the head disk assembly is bumped or jarred. Thus the heads 22 are prevented from damaging the data surface of the disk 1 .

Thus, there has been described herein a carriage retention device for use in a head disk assembly of a disk drive. A ferrous metal ball 36 is embedded at a location along the length of the carriage that positions the ferrou metal ball in a low gradient of flux density in the non- uniform magnetic field of the actuator magnet 38 when head 22 are extended over the data tracks of the disks 14 and positions the ferrous metal ball 36 in a higher gradient o flux density in the non-uniform magnetic field of the actuator magnetic 38 when the heads 22 are over the landin area of the disks 14. When the current lowing through th coil 32 of the actuator is removed but the heads 22 are still positioned over the data tracks of the disk 14, a magnetic force on the ferrous metal ball 36 due to its position on the carriage and in the non-uniform magnetic field moves the carriage to the parked position. This magnetic force is not sufficient to interfere with the positioning of the heads during normal operation (e.g., current flowing, through the coil 32) . Furthermore, when the carriage is in the parked position the magnetic force on the ferrous metal ball 36 is increased compared to the force when the carriage has the heads 22 over the data tracks of the disks 14. This increased force is sufficien to hold the carriage in the parked position during spin up before current is applied to the coil 32 for normal seek operations and to hold the carriage in the parked position even when the head disk assembly is moved. It will be understood that various changes in the details, arrangements and configurations of the parts and system which have been described and illustrated above in order t explain the nature of the present invention may be made by those skilled in the art within the principle and scope of the present invention as expressed in the appended claims.

Effect of the invention:

In a head disk assembly of a disk drive for storing data, there is a need for holding the carriage against the crash stop to avoid damage to the disks. In prior art, to hold the carriage against the crash stop, additional large permanent magnets or special additional circuitry were provided. A ferrous metal ball which is located in a position which is influenced by a non uniform magnetic field is used to hold the carriage in the parked position and prevent disk damange by crash stop.

Claims

What is claimed i :
1. A carriage assembly with a retention device or use in a head disk assembly of a disk drive having at leas one disk for storing data, said data being accessible by a head, said disk having a predetermined landing area for landing said head when not in use, comprising: a carriage for supporting and positioning said head relative to said disk, said carriage being mounted fo motion between a first position corresponding to a maximum displacement of said head from said landing area and a second position corresponding to the placement of said hea at said landing area; a coil held by said carriage and connected for receiving electrical current; a fixed magnet assembly disposed adjacent to sai coil for generating a magnetic force on said carriage to move said carriage between said first position and said second position responsive to said current flowing in sai coil; and, restoring means connected to said carriage for moving said carriage from any position between said first and second positions to said second position absent a flo of said current in said coil.
2. The carriage assembly of claim 1 wherein said carriage is mounted for swivelling motion between said first position and said second position, and wherein said restoring means is embedded within said carriage so that said restoring means does not substantially extend from said carriage and thereby does not occupy additional space within said head disk assembly.
3. A carriage assembly with a retention device for use in a head disk assembly of a disk drive having a disk for storing data, said data being accessible by a head, said disk having a predetermined landing area for landing said head when not in use, comprising: a carriage for supporting and positioning said head relative to said disk, said carriage being mounted fo motion between a first position corresponding to a maximum displacement of said head from said landing area and a second position corresponding to the placement of said hea at said landing area; a coil held by said carriage for receiving electrical current; a fixed magnet assembly disposed adjacent to sa coil for generating a first magnetic force on said carria to move said carriage between said first position and sai second position responsive to said current flowing in sai coil, said magnet assembly producing a non-uniform magneti field having a low gradient of flux density region and a higher gradient of flux density region; and, a ferrous metal body connected to said carriage at a location so that said ferrous metal body is within said low gradient of flux density region when said carriag is in said first position and within said higher gradient of flux density region when said carriage is in said secon position thereby exerting a second magnetic force on said ferrous body sufficient to move said carriage from a point between said first position and said second position towar said second position absent a flow of said current in said coil, said second magnetic force being sufficient to hold said carriage in said second position until said current flows in said coil.
4. A carriage assembly as in claim 3, including a crashstop adjacent to said second position, said crashstop restraining the motion of said carriage in at least one direction when said carriage is in said second position.
5. A method of returning a carriage of a head disk assembly of a disk drive to a parked position when power i withdrawn during normal operation, said head disk assembly having at least one' disk for storing data, said data being accessible by a head supported on said carriage, said disk having a predetermined area for landing said head when sai carriage is in said parked position, said carriage being mounted for motion between a first position corresponding to a maximum displacement of said head from said landing area and said parked position, a coil held by said carriag for receiving a current, a fixed magnet assembly adjacent to said coil for generating a first force on said carriage to move said carriage between said first position and said parked position responsive to said current flowing in said coil and a ferrous metal body connected to said carriage, said method comprising the steps of: generating a non-uniform magnetic field having a low gradient of flux density region and a higher gradient of flux density region; and, positioning said ferrous metal body at said low gradient of flux density region when said carriage is in said first position thereby exerting a magnetic force on said ferrous metal body sufficient to move said carriage toward said parked position absent a flow of said current in said coil.
6. A method of retaining a carriage of a head disk assembly of a disk drive in a parked position during spin up of said head disk assembly, said head disk assembly having a disk for storing data, said data being accessible by a head supported on said carriage, said disk having a predetermined area for landing said head when said carriag is in said parked position, said carriage being mounted fo motion between a first position corresponding to a maximum displacement of said head from said landing area and said parked position, a coil held by said carriage for receivin a current, a fixed magnet assembly adjacent to said coil for generating a force on said carriage to move said carriage between said first position and said parked position responsive to said current flowing in said coil and a ferrous metal body connected to said carriage, said method comprising the steps of: generating a non-uniform magnetic field having a low gradient of flux density region and a higher gradient of flux density region; and, positioning said ferrous body at said higher gradient of flux density region when said carriage is at said parked position thereby exerting a magnetic force on said ferrous metal body sufficient to hold said carriage i said second parked position until said current flows in said coil.
PCT/US1993/002743 1992-03-16 1993-03-16 Carriage retention device for disk drives WO1993019460A1 (en)

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Cited By (5)

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DE4441709A1 (en) * 1993-12-17 1995-06-22 Fujitsu Ltd Magnetic disc drive with safety parking position for actuator
US5734527A (en) * 1996-10-07 1998-03-31 International Business Machines Corporation Disk drive magnetic actuator latch mechanism having a latch lever with magnetic members on each end thereof for latching and unlatching the actuator using voice coil motor magnet
DE4447652C2 (en) * 1993-12-17 1998-07-23 Fujitsu Ltd Magnetic disc drive with safety parking position for actuator
US6731468B2 (en) 2001-04-11 2004-05-04 Samsung Electronics Co., Ltd. Pawl latch for ramp loading hard disk drivers
US7248441B2 (en) 2002-04-04 2007-07-24 Samsung Electronics Co., Ltd. Disk drive actuator parking method using impact rebound crash stop with bias tab and pusher and crash stop faces

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Title
PATENT ABSTRACTS OF JAPAN vol. 7, no. 127 (P-201)3 June 1983 & JP,A,58 045 670 ( MATSUSHITA ) 16 March 1983 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4441709A1 (en) * 1993-12-17 1995-06-22 Fujitsu Ltd Magnetic disc drive with safety parking position for actuator
DE4447652C2 (en) * 1993-12-17 1998-07-23 Fujitsu Ltd Magnetic disc drive with safety parking position for actuator
US5801907A (en) * 1993-12-17 1998-09-01 Fujitsu Limited Magnetic disk drive with automatic actuator and locking structure
US5734527A (en) * 1996-10-07 1998-03-31 International Business Machines Corporation Disk drive magnetic actuator latch mechanism having a latch lever with magnetic members on each end thereof for latching and unlatching the actuator using voice coil motor magnet
US6731468B2 (en) 2001-04-11 2004-05-04 Samsung Electronics Co., Ltd. Pawl latch for ramp loading hard disk drivers
US7248441B2 (en) 2002-04-04 2007-07-24 Samsung Electronics Co., Ltd. Disk drive actuator parking method using impact rebound crash stop with bias tab and pusher and crash stop faces

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