Abstract:
A storage drive receives thereinto, retains, and ejects therefrom a removable storage media cartridge having storage media. The storage drive has an actuator including a carriage assembly with a head mounted thereto. The actuator moves the head as mounted to the carriage assembly with respect to the storage media of the retained media cartridge. The storage drive also has a head locking lever for locking the carriage assembly in a retracted position and unlocking same, and a multi-coil solenoid for actuating the head locking lever.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a disk drive having a solenoid with multiple coils. More particularly, the present invention relates to such a disk drive were the multi-coil solenoid actuates multiple functions.  
         BACKGROUND OF THE INVENTION  
         [0002]    A disk drive for receiving a removable disk is known. Examples of a disk drive include a conventional 3.5 inch ‘floppy’ disk drive, a ZIP disk drive as developed and marketed by IOMEGA Corporation of Roy, Utah, and the like. Such a disk drive is typically coupled to a processor or the like, and facilitates an exchange of information between the processor and the disk. The disk and the disk drive may be magnetically or optically based, for example.  
           [0003]    The aforementioned disk may be housed within a disk cartridge, and can rotate freely within the cartridge. The disk may be mounted on a coaxial hub or may define a coaxial aperture, and the hub or aperture of the disk is externally accessible by way of an access aperture defined in one of the planar panels of the cartridge. Typically, the disk drive includes a frame or chassis and a disk motor which is mounted thereto, wherein during operation of the drive, the motor engages the hub or aperture of the disk through the cartridge access aperture and applies a rotating force to the disk by way of such hub or aperture.  
           [0004]    The disk may be inserted into, retained within, and ejected from the disk drive by way of any of a variety of mechanisms. In at least some arrangements, the ejection aspect of the mechanism includes a lever or the like, and is actuated by way of a plunger of a solenoid contacting and appropriately moving the lever or the like. Ejection of a disk or disk cartridge is generally known or should be apparent to the relevant public and therefore need not be discussed herein in any detail.  
           [0005]    As retained within the disk drive, the disk is brought into contact with one or more read/write heads for reading data from and/or writing data to the disk. The heads are moved relative to the disk by a head assembly which includes the heads. Typically, the head assembly moves the heads to a retracted position and locks the heads in such retracted position when the heads are not expected to be active. Accordingly, the non-active heads are protected from damage and the like. In at least some arrangements, and similarly, to release the locked heads, the head assembly includes a lever or the like that is actuated by way of a plunger of a solenoid contacting and appropriately moving the lever or the like. Releasing a locked head assembly is generally known or should be apparent to the relevant public and therefore need not be discussed herein in any detail.  
           [0006]    Also, prior to ejecting the disk, the head assembly typically retracts or moves the heads away from the disk to avoid damage to the heads and the disk during such ejection. In at least some arrangements, the retraction aspect of the head assembly is embodied as a lever or the like, and is actuated by way of a plunger of a solenoid contacting and appropriately moving the lever or the like. Retraction of a head assembly is generally known or should be apparent to the relevant public and therefore need not be discussed herein in any detail. Typically, the retraction lever or the like of the head assembly and the head release lever or the like of the head assembly are separate (although they could be one and the same), ejection occurs by moving the lever a relatively large distance, and head lock/release occurs by moving the lever a relatively small distance.  
           [0007]    Typically, the solenoid and plunger that actuates the ejection lever or the like is also the solenoid and plunger that actuates the retraction lever and head release lever, and such solenoid and plunger actuates ejection after actuating head lock/release. Actuating head lock/release may be accomplished with a relatively short stroke of the plunger by the solenoid, and actuating ejection may be accomplished with a relatively long stroke of the plunger by the solenoid. A solenoid and a disk drive having such a solenoid is set forth in more detail in U.S. Pat. No. 5,650,891, hereby incorporated by reference in its entirety.  
           [0008]    Preferably, a disk drive mounted to a computer by way of a host port of the computer is powered through the host port and therefore does not require an external power supply. However, a solenoid such as the retraction/ejection/head release solenoid discussed above typically requires a relatively high operating current that is either a strain on the host port of a computer or that is not available from the host port of a computer.  
           [0009]    Preferably, the solenoid as mounted to the disk drive is relatively short in height so that the overall disk drive can have a relatively small height (i.e., in a direction generally normal to the general planar extent of the disk drive). However, a solenoid such as the retraction/ejection/head release solenoid discussed above typically is relatively tall in height in order to generate the kind of magnetic flux necessary to actuate the plunger, especially for a relatively long plunger stroke.  
           [0010]    Accordingly, a need exists for a disk drive having a solenoid with relatively low operating current and a relatively low height.  
         SUMMARY OF THE INVENTION  
         [0011]    The present invention satisfies the aforementioned need by providing a storage drive for receiving thereinto, retaining, and ejecting therefrom a removable storage media cartridge having storage media. The storage drive has an actuator including a carriage assembly with a head mounted thereto. The actuator moves the head as mounted to the carriage assembly with respect to the storage media of the retained media cartridge. The storage drive also has a head locking lever for locking the carriage assembly in a retracted position and unlocking same, and a multi-coil solenoid for actuating the head locking lever. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The foregoing summary as well as the following detailed description of the present invention will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. As should be understood, however, the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:  
         [0013]    [0013]FIG. 1 is a perspective view of a typical data storage device, or disk drive;  
         [0014]    [0014]FIG. 2 is a perspective view of a disk cartridge for use with the disk drive of FIG. 1;  
         [0015]    [0015]FIG. 3 is a bottom view of the disk cartridge of FIG. 2;  
         [0016]    [0016]FIG. 4 is a top view of the data storage device of FIG. 3 with a top cover of the device housing removed;  
         [0017]    FIGS.  5 - 7  are top views of the data storage device of FIG. 4 illustrating the insertion of a disk cartridge into the device;  
         [0018]    [0018]FIG. 8 illustrates further details of a portion of the data storage device of FIG. 3;  
         [0019]    FIGS.  9 - 12  illustrate further details of the operation of a first movable member and a second movable member in accordance with the present invention;  
         [0020]    [0020]FIG. 13 is a perspective view of a portion of the data storage device of FIGS.  1 - 12 , and in particular shows the single-coil solenoid thereof;  
         [0021]    [0021]FIG. 14 is a top plan view of the single-coil solenoid of FIG. 13;  
         [0022]    [0022]FIG. 15 is a schematic top plan view of the single-coil solenoid of FIG. 13;  
         [0023]    [0023]FIG. 16 is a perspective view of a portion of a data storage device such as that of FIGS.  1 - 12 , and in particular shows a multi-coil solenoid thereof in accordance with one embodiment of the present invention;  
         [0024]    [0024]FIG. 17 is a perspective view of the multi-coil solenoid of FIG. 16; and  
         [0025]    [0025]FIG. 18 is a schematic top plan view of the multi-coil solenoid of FIG. 16. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0026]    Certain terminology may be used in the following description for convenience only and is not considered to be limiting. For example, the words “left”, “right”, “upper”, and “lower” designate directions in the drawings to which  20  reference is made. Likewise, the words“inwardly” and“outwardly” are directions toward and away from, respectively, the geometric center of the referenced object. The terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import.  
         [0027]    Referring now to FIG. 1, there is shown a typical disk drive  40 . As was discussed above, the disk drive  40  is for receiving a removable disk (not shown) such as a conventional 3.5 inch ‘floppy’ disk or a“ZIP” disk as developed and marketed by IOMEGA Corporation of Roy, Utah, and the like. As seen, the disk drive  40  comprises an outer housing  42  having top and bottom covers  44 ,  46  and a front panel  48 . A disk cartridge  10  (FIGS. 2 and 3) can be inserted into the disk drive  40  through a horizontal opening  51  in the front panel  48  of the disk drive  40 . An eject button is also provided on the front panel for automatically ejecting a retained disk cartridge from the disk drive  40 . The disk drive  40  shown in FIG. 1  is a stand-alone unit, although the disk drive  40  of the present invention as disclosed below is particularly suited as an internal disk drive of a computer (not shown).  
         [0028]    [0028]FIGS. 2 and 3 show an exemplary disk cartridge  10  adapted for use in the disk drive  40  of FIG. 1. As shown, the disk cartridge  10  comprises an outer casing  12  having upper and lower shells  22 ,  24  that mate to form the casing. A disk-shaped recording medium (not shown) is affixed to a hub  16  that is rotatably mounted in the casing  12 . An opening  21  on the bottom shell  24  of the casing  12  provides access to the disk hub  16 . A head access opening  30  in the front peripheral edge  20  of the disk cartridge  10  provides access to the recording surfaces of the disk (not shown) by the recording heads of the disk drive. A shutter  18  (not shown in FIG. 2) is provided on the front peripheral edge  20  of the disk cartridge  10  to cover the head access opening  30  when the cartridge is not in use. When the cartridge is inserted into the disk drive, the shutter  18  moves to the side exposing the head access opening  30  and thereby providing the heads of the drive with access to the recording surface of the disk (not shown). In the present embodiment, the casing houses a flexible or floppy magnetic disk, however, in other embodiments, the disk may comprise a rigid magnetic disk, a magneto-optical disk or an optical storage medium.  
         [0029]    The opposite front corners of the disk cartridge  10  have a non-square shape defined by angled surfaces  20   c ,  20   d  that angle away from the front peripheral edge  20  of the cartridge at a predetermined angle. Additionally, a pair of projections  20   a ,  20   b  are formed on the front peripheral edge  20  of the cartridge. Each projection  20   a ,  20   b  is formed adjacent a respective one of the angled surfaces  20   c ,  20   d  at the point where the respective surface  20   c ,  20   d  begins to angle away from the plane of the front peripheral edge  20  of the cartridge  10 .  
         [0030]    [0030]FIG. 4 is a top view of the disk drive  40  of FIG. 1 with the top cover  44  removed. The disk drive  40  comprises an internal platform  50  that slides along opposing side rails  52 ,  54  between a forward position (FIG. 4) and a rearward position (FIG. 7). A pair of springs  56 ,  58  bias the platform  50  toward its forward position.  
         [0031]    An actuator  60 , which in the preferred embodiment comprises a linear actuator, is mounted to the rear of the platform  50 . The linear actuator  60  comprises a carriage assembly  62  having two lightweight flexible arms  64 ,  66 . The recording heads  18 , 19  of the disk drive are mounted at the ends of the respective arms  64 ,  66 . A coil  68 , which is part of a voice coil motor, is mounted at the opposite end of the carriage  62 . The coil  68  interacts with magnets (not shown) to move the carriage linearly so that the heads  18  and  19  can move radially over respective recording surfaces of a disk cartridge inserted into the disk drive.  
         [0032]    A raised wall  53  is formed on the platform. The raised wall  53  extends across the width of the platform  50 , perpendicularly to the direction of motion of the carriage  62 . The raised wall  53  defines an eject member that engages the front peripheral edge  20  of the disk cartridge  10  upon insertion of the disk cartridge into the disk drive. The opposite side edges  55   a ,  55   b  of the eject member  53  are angled in the same manner as the opposite front corners  20   c ,  20   d  of the disk cartridge  10 . Thus, the shape of the eject member  53  mirrors the contour of the forward end face of the cartridge. As further shown, the front surface  57  of the eject member  53  has a pair of projections  53   a ,  53   b  positioned near the angled surfaces  55   a ,  55   b.    
         [0033]    The disk drive  40  further comprises a spindle motor  82  capable of rotating the recording medium of a disk cartridge at a predetermined operating speed. In the present embodiment, the spindle motor  82  is coupled to the platform  50 . When a disk cartridge is inserted into the disk drive, the hub  16  of the disk cartridge engages the spindle motor  82  of the disk drive  40  when the platform reaches its rearward position.  
         [0034]    As embodied in the disk drive  40  illustrated herein, the disk drive  40  comprises a first movable member movably mounted in the disk drive for performing a respective function. In the embodiment described herein, the first movable member comprises an eject latch lever  70  movably mounted within the disk drive  40 . As described hereinafter, the eject latch lever  70  functions to releasably latch the platform  50  in its rearward position. In the present embodiment, the eject latch lever  70  is pivotally mounted on the platform  50  about a rotation shaft  70   b . A first spring (not shown) is coupled to the eject latch lever  70  (i.e., first movable member) at the rotation shaft  70   b  in order to bias the lever  70  in a first direction (e.g., the X+direction). The eject latch lever  70  has a cutout  70   a  adapted to releasably engage a latch projection  78  as the platform  50  moves backward into its rearward position. The biasing force of the first spring  90  urges the eject latch lever  70  into this latched position. In one embodiment, the latch projection  78  is formed as part of the top cover  44  (not shown) of the disk drive  40 .  
         [0035]    The disk drive  40  also comprises a second movable member movably mounted within the disk drive  40 . In the embodiment described herein, the second movable member comprises a head locking lever  72  that is pivotally mounted on the platform  50  about a rotation shaft  72   b . As described hereinafter, the head locking lever  72  functions to lock and unlock the carriage  62  of the linear actuator  60 . A second spring (not shown) is coupled to the head locking lever  72  (i.e., second movable member) at its rotation shaft  72   b  to bias the head locking lever  72  in the same direction as the eject latch lever  70  (i.e., the X+direction). An end  72   a  of the head locking lever, which extends at a right angle to the main shaft of the lever  72 , is adapted to releasably engage an end  62   a  of the actuator carriage  62  when the carriage  62  is in a fully retracted position, thereby locking the carriage in place and preventing inadvertent movement of the recording heads  18 ,  19 .  
         [0036]    A single electro-mechanical device comprising a solenoid  74  is mounted on the platform  50  and has a plunger  76 . When the solenoid  74  is energized by an electrical current, the plunger  76  moves in the X−direction from a normally extended position toward a retracted position. As the plunger  76  of the solenoid  74  moves toward its retracted position, an enlarged operating end  76   a  of the plunger  76  engages the first and second movable members (e.g., eject latch and head locking levers  70 ,  72 ) in order to pull the members in the X−direction against the respective biasing forces of the first and second springs  90 ,  92 .  
         [0037]    FIGS.  5 - 7  illustrate the insertion of a disk cartridge  10  into the disk drive  40 . For purposes of illustration only, some components of the disk drive  40  are not shown. Referring to FIG. 5, a disk cartridge  10  is inserted into the disk drive  40  through the opening  51  in the front panel  48  of the disk drive  40 . Initially, the platform  50  is in its forward position, as shown. As the disk cartridge  10  is pushed farther into the disk drive  40 , the pair of projections  20   a ,  20   b  on the forward end  20  of the cartridge  10  engage the corresponding pair of projections  53   a ,  53   b  on the front surface of the eject member  53  of the platform  50 . Thereafter, the disk cartridge  10  and platform  50 , including the eject member  53 , move together rearwardly against the biasing force of the springs  56 ,  58  (FIG. 4).  
         [0038]    The platform  50  rides in slots (not shown) along the opposing side rails  52 ,  54 . The slots (not shown) in the opposing side rails  52 ,  54  are contoured such that, as the platform  50  and disk cartridge  10  move rearwardly, the elevation of the platform  50  changes. Specifically, the platform  50  rises in order to bring the spindle motor  82  of the disk drive  40  into engagement with the hub  16  of the disk cartridge  10 . Engagement of the hub  16  and spindle motor  82  is completed when the platform  50  reaches its final rearward position (FIG. 7).  
         [0039]    Referring to FIG. 6, as the platform  50  approaches its rearward position, the portion of the eject latch lever  70  just rearward of the cutout  70   a  contacts an angled surface  78   a  of the latch projection  78 . As the disk cartridge  10  pushes the platform  50  farther to the rear of the disk drive, the eject latch lever  70  rides along the angled surface  78   a  pushing the eject latch lever  70  to the side (i.e., X−direction) against its normal spring bias. As shown in FIG. 7, when the platform reaches its full rearward position, the eject latch lever  70  springs back in the X+direction such that the cutout  70   a  engages the latch projection  78 . This latches the platform  50 , and hence the eject member  53 , in its rearward position and maintains the disk cartridge  10  in the disk drive  40 . In this manner, the eject latch lever is said to be self-latching.  
         [0040]    The eject member  53  may alternately be formed separately from the platform  50  and the platform  50  may be stationary. In such case, the eject member  53  alone will move from the forward position to the rearward position, and the eject latch lever  70  will be adapted to latch the eject member  53  in its rearward position. Also alternately, the platform  50  may be omitted.  
         [0041]    [0041]FIG. 8 is a rear end view of the disk drive  40  illustrating the latched position of the eject lever  70 . As shown, the eject lever  70  has an elongate, downwardly extending projection  80  that extends downwardly from the lever  70  toward a circuit board  86  mounted on the bottom cover  46  of the disk drive housing. A switch  84  having a plunger  82  is mounted on the circuit board  86 . When the platform  50  reaches the rearward position and the cutout  70   a  engages the latch projection  78 , the projection  80  extending from the eject lever  70  moves against the plunger  82  thereby activating the switch  84 . A controller (not shown) in the disk drive can sense the activation of the switch  84  and be alerted that the platform  50  has moved into the latched, rearward position. The controller can then initiate rotation of the spindle motor and can signal the solenoid  74  to move the head locking lever  72  and release the linear actuator.  
         [0042]    Referring now to FIGS.  9 - 12 , the structure and operation of the solenoid  74  and the first and second movable members (i.e., levers  70 ,  72 ) is described in greater detail. The single solenoid  74  is adapted to move the first and second members independently in order to selectively perform their respective functions. In particular, the solenoid is adapted to move the eject latch lever  70  (i.e., first member) and head locking lever  72  (i.e., second member) in order to selectively unlatch the platform  50  and/or unlock the carriage of the head actuator  53 . It is understood that the eject latch and head locking levers  70 ,  72  shown represent merely one implementation. Alternately, the first and second movable members may comprise other movable components adapted to perform other disk drive functions. The following discussion of the operation of the eject latch and head locking levers  70 ,  72  is intended merely to illustrate one exemplary implementation.  
         [0043]    Each of the movable members (i.e., eject latch and head locking levers  70 ,  72 ) has a small projection  70   c ,  72   c  positioned in the path of movement of the enlarged end  76   a  of the solenoid shaft  76 . As the plunger  76  of the solenoid moves in the X−direction from its normally extended position (FIG. 9) to its fully retracted position (FIG. 11), the enlarged end  76   a  of the plunger  76  engages with the respective projections  70   c ,  72   c  on the levers  70 ,  72 , moving the levers  70 ,  72  against the respective biasing forces of the first and second springs  90 ,  92 .  
         [0044]    As best shown in FIGS. 9 and 12, the respective projections  70   c ,  72   c  are positioned relative to the enlarged end  76   a  of the plunger  76  such that the end  76   a  of the plunger will contact the projection  72   c  on the head locking lever  72  (i.e., first movable member) first and will move the head locking lever  72  a predetermined distance to an intermediate position (FIG. 10) of the plunger  76  before engaging the projection  70   c  on the eject lever  70 . As such, the head locking lever  72  can be moved independently of the eject lever  70 .  
         [0045]    The biasing force of the first spring  90  is greater than the biasing force of the second spring  92 . As such, the solenoid  74  can be energized with an electrical signal having a first current that is sufficient to move the plunger  76  of the solenoid  74  against the biasing force of the second spring  92  but is insufficient to move the plunger  76  against the biasing force of the first spring  92 . As shown in FIG. 10, when it is desired to unlock the carriage  62  of the head actuator  60 , an electrical signal having this first current can be applied to the solenoid  74  causing the plunger  76  of the solenoid  74  to move in the X−direction pulling the head locking lever  72  out of engagement with the end  62   a  of the actuator carriage  62 . However, because the first current is insufficient to overcome the biasing force of the first spring  90 , the plunger  76  will stop moving when the enlarged end  76   a  of the plunger  76  reaches its intermediate position and contacts the projection  70   c  on the eject latch lever  70 . Thus, in this case, the head locking lever  72  moves to a disengaged position, while the eject lever  70  remains in its latched position. Once the actuator carriage  62  has moved forward and begun its normal operation, the first current can be removed from the solenoid  74  allowing the plunger  76  of the solenoid  74  to move back to its extended position (FIG. 9). At the same time, the second spring  92  will urge the head locking lever  72  back to the position shown in FIG. 9.  
         [0046]    Like the eject latch lever  70 , the head locking lever  72  is self-latching or self-engaging. That is, when the head locking lever  72  is in the position shown in FIG. 9 and the rear end  62   a  of the carriage  62  moves back toward the rear of the disk drive, the rear end  62   a  contacts an inclined surface  72   d  at the end  72   a  of the lever  72 . As the carriage  62  moves farther to the rear, the end  62   a  of the carriage will ride along the inclined surface  72   d  of the head locking lever  72  causing the head locking lever  72  to move to the side against the bias of spring  92 . Once the carriage  62  reaches its full rearward position, the head locking lever  72  will spring back to its engaged position, and the carriage  62  will once again be locked in place, as illustrated in FIG. 9. More specifically, as shown in FIG. 9, the end  72   a  of the head locking lever  72  locks the carriage  62  in place (i.e., engages the carriage  62 ) by blocking the rear end surface  62   b  of the carriage  62 . It is desirable to lock the carriage in place whenever the disk drive  40  is not in use, or a disk cartridge has been removed from the disk drive  40 .  
         [0047]    Referring now to FIG. 11, when it is desired to eject a disk cartridge from the disk drive, the eject button  52  on the front panel  48  of the disk drive  40  is pushed. A processor (not shown) in the disk drive detects the activation of the eject button and applies an electrical signal to the solenoid  74  having a second, stronger current than the first current that is sufficient to overcome the combined biasing force of both the springs  90 ,  92 . In this case, the plunger  76  of the solenoid  74  moves from its extended position to its fully retracted position. As the plunger  76  moves to its fully retracted position, the enlarged operating end  76   a  of the plunger engages the projections  70   c ,  72   c  on both levers  70 ,  72  pulling both levers in the X−direction. This causes the cutout  70   a  on the eject latch lever  70  to disengage from the latch projection  78 , thereby releasing the platform  50  (i.e., eject member  53 ). Once released, the platform  50  moves back to its forward position under the force of springs  56 ,  58 . As the platform  50  moves back to the forward position, the disk cartridge is backed out of the opening  51  and can then be removed by a user. Immediately after unlatching the platform  50 , the second current is removed from the solenoid  74  so that the eject latch lever  70  and head locking lever  72  spring back to the positions shown in FIG. 5.  
         [0048]    The magnitudes of the first and second currents required to overcome the biasing forces of the first and second springs are highly dependent on the characteristics of the particular solenoid employed. Significantly, though, the maximum current required by the solenoid  74  of the typical disk drive  40  is believed to be relatively high as compared to the maximum current available to the disk drive  10  from a host port of a typical computer. Thus, the disk drive  40  in an internal configuration (not shown) may require an external power supply.  
         [0049]    Additionally, the solenoid  74  as mounted to the disk drive is relatively tall in height so that the overall disk drive  40  is relatively tall (i.e., in a direction generally normal to the general planar extent of the disk drive). Thus, the disk drive  40  in an internal configuration (not shown) may require excessive height space within a typical computer housing.  
         [0050]    Referring now to FIGS.  13 - 15 , the solenoid  74  of the disk drive  40  of FIGS.  1 - 12  is shown in more detail. In particular, and as seen, the solenoid  74  is an open frame single-coil solenoid and has the aforementioned single coil E 1  wrapped on a bobbin E 2 , where the bobbin E 2  with coil E 1  is mounted to a frame E 3 . Such frame E 3  includes a generally U-shaped first piece E 4  having a rear portion E 5  and side portions E 6 , and a second piece E 7  comprising a front portion. As may be appreciated, the distal ends of the side portions E 6  are coupled to the ends of the second piece E 7  such that the frame E 3  is generally rectangular. As may also be appreciated, the bobbin E 2  with coil E 1  is mounted to the frame E 3  such that the axis of the coil E 1  is generally interposed between and extends generally parallel with the side portions E 6  of the first piece E 4  of the frame E 3 .  
         [0051]    In operation, the coil E 1  is energized to develop a flux path E 8  that extends down the axis of the coil E 1  toward the second piece E 7  of the frame E 3 , then through the second piece E 7  toward each end thereof, then up each side portion E 6  toward the rear portion E 5 , then through the rear portion E 5  from each side portion E 6  and toward the central area of such rear portion E 5 , and then back down the axis of the coil E 1 . With such flux path E 8 , then, a plunger E 9  mounted to the second piece E 7  of the frame is drawn up the axis of the coil El and within the coil E 1 , bobbin E 2 , and frame E 3 . Note that such flux path E 8  includes a split where the flux diverges in the second piece E 7 .  
         [0052]    In one embodiment of the present invention, to reduce the maximum current required by the solenoid of the typical disk drive  40 , and/or to reduce the height of the solenoid of the typical disk drive  40 , the single-coil solenoid  74  of FIGS.  1 - 15  is replaced by a multi-coil solenoid  74   m , as in FIGS.  16 - 18 . In particular, and as seen, the multi-coil solenoid  74   m  has a pair of coils E 10 , E 11  wrapped on respective bobbins E 12 , E 13 , where each bobbin E 12 , E 13  with respective coils E 10 , E 11  is mounted to a frame E 14  in a side-by-side manner.  
         [0053]    Here, the frame E 14  includes a front plate E 15  and a back plate E 16 , but does not include any side portions as with the solenoid  74  of FIGS.  1 - 1   5 . As may be appreciated, the front plate E 15  and the back plate E 16  do not physically contact one another. As may also be appreciated, the bobbins E 12 , E 13  with coils E 10 , E 11  are mounted to the frame E 14  such that the axes of the coils E 10 , E 11  are generally parallel to one another and are generally normal to the planar extents of each of the front plate E 15  and the back plate E 16 .  
         [0054]    In operation, the coils E 10 , E 11  are energized to develop a flux path E 17  that extends down the axis of the coil E 10  toward the front plate E 15 , across the front plate E 15  toward the axis of the coil E 11 , up the axis of the coil E 11  toward the back plate E 16 , across the back plate E 16  toward the axis of the coil E 10 , and then back down the axis of the coil E 10 . With such flux path E 17 , then, a plunger E 18  mounted to the front plate E 15  of the frame E 14  is drawn up the axis of the coil E 10  and within the coil E 10  and bobbin E 12 . Note that such flux path E 17  is a single loop and therefore includes no split such as in the case of the flux path E 8  of the solenoid  74  of FIGS.  1 - 15 .  
         [0055]    Note that in operating the coils E 10 , E 11 , actuation of the head lock lever  72  only and not the eject lever  70  may be achieved by applying a relatively lesser current to both coils E 10 , E 11 , and actuation of both the head lock lever  72  and the eject lever  70  may be achieved by applying a relatively greater current to both coils E 10 , E 11 . Alternatively, actuation of the head lock lever  72  only and not the eject lever  70  may be achieved by applying a current to one of the coils E 10 , E 11 , and actuation of both the head lock lever  72  and the eject lever  70  may be achieved by applying a current to both coils E 10 , E 11 . The amounts of current applied vary based on the particulars of the solenoid  74   m , and at any rate in any particular situation are known or should be apparent to the relevant public and therefore need not be described herein in any detail.  
         [0056]    Importantly, to produce the same effect on the respective plungers E 9 , E 18 , the multiple coils E 10 , E 11  of the solenoid  74   m  of the present invention as shown in FIGS.  16 - 18  operate at a maximum current that is significantly less than the maximum current of the single coil E 1  of the solenoid  74  of FIGS.  1 - 15 . That is, the multiple coils E 10 , E 11  and the overall design of the solenoid  74   m  of the present invention as shown in FIGS.  16 - 18  are more efficient than the single coil E 1  of the solenoid  74  of FIGS.  1 - 15 . In fact, it has been shown empirically that the maximum current employed by the multiple coils E 10 , E 11  of the solenoid  74   m  of the present invention as shown in FIGS.  16 - 18  is about one-third that of the maximum current employed by the single coil E 1  of the solenoid  74  of FIGS.  1 - 1   5 . Accordingly, a disk drive  40  having the solenoid  74   m  of the present invention is more amenable to being supplied with power solely through the host port of a typical computer, and is less susceptible to the need for an external power source.  
         [0057]    Also importantly, the solenoid  74   m  of the present invention having the multiple coils E 10 , E 11  can be constructed to have a smaller height (i.e., in a direction generally normal to the general planar extent of the disk drive  40 ) as compared to the solenoid  74  having the single coil E 1 , and/or can be constructed to require less current as compared to the solenoid  74 . In particular, the coils E 10 , E 11  may have less windings than the coil E 1 , in which case the coils E 10 , E 11  are shorter, may have more windings than the coil E 1 , in which case the coils E 10 , E 11  use less current, or a combination thereof. Thus, a disk drive  40  having the solenoid  74   m  of the present invention may be constructed to have a smaller height as compared with a disk drive  40  having the solenoid  74 , and/or may be constructed to use less current.  
         [0058]    In the foregoing description, it can be seen that the present invention comprises a new and useful solenoid  74   m  and disk drive  40  having such solenoid  74   m , where the solenoid  74   m  has a relatively low operating current and a relatively low height. It should be appreciated that changes could be made to the embodiments described above without departing from the inventive concepts thereof. It should be understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.