Abstract:
An optical path or waveguide for a laser-assisted transducing head is disclosed. The optical path extends between the poles of the transducing head to near the write gap. A solid-state laser is attached to or incorporated into the slider or head and is positioned to direct thermal energy through a waveguide and onto a track of a read/write surface to lower the coercivity of the recording medium to facilitate the write process.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This Application is a continuation application of U.S. Ser. No. 11/328,847, filed Jan. 10, 2006, which is a continuation application of U.S. Ser. No. 10/600,561, filed Jun. 19, 2003, now U.S. Pat. 6,996,033, which is a non-provisional of U.S. Ser. No. 60/389,802 filed Jun. 19, 2002 and 60/413,190 filed Sep. 24, 2002; the subject matters of which are hereby incorporated by reference in their entirety. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    This invention was made with United States Government support under Agreement No. 70NANB1H3056 awarded by the U.S. Department of Commerce, National Institute of Standards and Technology (NIST), Advanced Technology Program. The United States Government has certain rights in the invention. 
     
    
     FIELD OF THE INVENTION 
       [0003]    This invention relates generally to magnetic recording heads, including a read element and a write element, for use in a data storage system such as a disk drive. More specifically, it relates to a path for an optical waveguide to carry thermal energy (e.g., light) to a location near the write portion of the magnetic recording head, to enable thermally-assisted writing. 
       BACKGROUND OF THE INVENTION 
       [0004]    Typical disk drive systems include suspensions for supporting a transducing head over information tracks of a rotatable disk. Typically, suspensions include a load beam or suspension having a mounting region on a proximal end, a flexure or gimbal on a distal end, a relatively rigid region adjacent to the flexure, and a spring region between the mounting region and the rigid region. An air bearing slider which holds the transducing head is mounted to the flexure. The mounting region is typically attached to a base plate for mounting the load beam to an actuator arm. A motor which is controlled by a servo control system rotates the actuator arm to position the transducing head over the desired information tracks on the disk. This type of suspension may be used with both magnetic and non-magnetic disks. 
         [0005]      FIG. 1  shows a top view of a known disk drive actuation system  10 , for positioning a transducing head (not shown) over a track of a  10  magnetic disk. The actuation system  10  includes, as shown from left to right in  FIG. 1 , a voice coil motor (“VCM”)  12 , an actuator arm  14 , a load beam or suspension  16 , a flexure  18 , and a slider  20 . The slider  20  is connected to the distal end of the suspension  16  by the flexure  18 . The load beam  16  is connected to the actuator arm  14  which is coupled to the VCM  12 . 
         [0006]    As shown on the right-hand side of  FIG. 1 , the disk drive assembly includes a disk  22  having a multiplicity of tracks  24  which rotate about an axis  26 . During operation of the disk drive assembly, the rotation of the disk  22  generates air movement which is encountered by the slider  20 . This air movement acts to keep the slider  20  aloft a small distance above the surface of the disk  22  allowing the slider  20  to “fly” above the surface of the disk  22 . Any wear associated with physical contact between the slider  20  and the disk  22  is thus minimized. 
         [0007]    As shown in  FIG. 2 , the flexure  18  provides a spring connection between the slider  20  and the load beam  16 . Flexure  18  is configured such that it allows the slider  20  to move in pitch and roll directions to compensate for fluctuations in the spinning surface of the disk  22 . Many different types of flexures  18 , also known as gimbals, are known to provide the spring connection allowing for pitch and roll movement of the slider  20  and can be used with the present invention. 
         [0008]    The VCM  12  is selectively operated to move the actuator arm  14  around an axis  28  thereby moving the load beam  16  and positioning the transducing head carried by the slider  20  between tracks  24  of disk  22 . Proper positioning of the transducing head is necessary for reading and writing of data on the concentric tracks  24  of the disk  22 . For a disk  22  having a high density, however, the VCM  12  lacks sufficient resolution and frequency response to position the transducing head on the slider  20  over a selected track  24  of the disk  22 . Therefore, a higher resolution microactuation system is often used. 
         [0009]    The density of concentric data tracks on magnetic disks continues to increase (i.e., the size of data tracks and radial spacing between data tracks are decreasing). In addition, the linear density continues to increase, which in turn increases the area bit density in both directions and reduced the area per magnetic bet cell. As the area per bit cell is reduced, the number of grains or particles per bit cell is also reduced unless the grain size is also reduced. The signal-to-noise ratio is a function of the number of grains per bit cell, so as this density increases, it becomes more difficult to write data to the tracks without affecting adjacent tracks. One technique in the art for enabling precise data writing is to use thermally-assisted laser writing. This technique requires the presence of a thermal energy source, such as a light beam (e.g., a laser beam) at or near the location of the transducing head. This thermal energy source provides energy to the recording medium, which reduces the medium&#39;s coercivity to facilitate the write process. 
         [0010]    Accordingly, there is a need in the art for an optical path or waveguide for directing light from a top surface of a slider down to a point near the write gap of the magnetic recording head. There is a further need for a system for directing a laser beam to a position near the transducing head and onto the recording medium. 
       BRIEF SUMMARY OF THE INVENTION 
       [0011]    The present invention, in one embodiment, is a magnetic recording head for writing data onto a magnetic recording medium. The head includes a first pole and a second pole separated by a gap. A coil structure traverses through the gap, and a waveguide extends through the gap, in a plane distinct from the first pole plane and the second pole plane. A closure partially connects the first pole and the second pole near the back gap to decrease a magnetic reluctance and increase a write efficiency of the recording head. 
         [0012]    Another embodiment of the present invention is a load beam assembly for transducing data with a concentric track of a magnetic recording medium. The assembly includes a slider including an air-bearing surface, and a transducing head mounted on a trailing face of the slider, the transducing head having a first pole and a second pole. The assembly further includes a light source attached near the trailing face, and a waveguide extending generally straight down from near an upper edge to near a lower edge of the trailing face, such that the waveguide is disposed in a distinct plane between the first and second poles. 
         [0013]    Yet another embodiment of the present invention is a method of fabricating a head/load beam assembly for writing data to a concentric track of a magnetic recording medium. The method comprises providing a slider having an air bearing surface, forming a transducing head on a trailing edge of the slider, the transducing head including a pole having a split back gap, forming a waveguide on the trailing face of the slider, the waveguide extending through the split back gap, and mounting a laser source near the trailing edge of the slider. 
         [0014]    While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description. As will be apparent, the invention is capable of modifications in various obvious aspects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0015]      FIG. 1  is a top view of a disk drive actuation system, as known in the prior art. 
           [0016]      FIG. 2  is a perspective view of a suspension, flexure, and slider of a disk drive actuation and positioning system, as known in the prior art. 
           [0017]      FIG. 3  is a perspective view of a head/gimbal assembly, according to one embodiment of the present invention. 
           [0018]      FIG. 4A  is a perspective view of a laser-attached slider, according to one embodiment of the present invention. 
           [0019]      FIG. 4B  is a perspective view of a laser-attached slider, according to a second embodiment of the present invention. 
           [0020]      FIG. 5A  is a perspective view of a transducing head, according to one embodiment of the present invention. 
           [0021]      FIG. 5B  is a sectional perspective view and cross-sectional view of a portion of a transducing head, according to one embodiment of the present invention. 
           [0022]      FIG. 6  is a perspective view of a head/gimbal assembly, according to another embodiment of the present invention. 
           [0023]      FIG. 7A  is a sectional view and  FIG. 7B  is a sectional perspective view of a slider, according to yet another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION  
       [0024]      FIG. 3  is a perspective view of a head/gimbal assembly  100 , according to one embodiment of the present invention. As shown in  FIG. 3 , the head/gimbal assembly  100  includes a gimbal or flexure  102 , a slider  104 , and a laser  106 . The assembly  100  can be mounted to any load beam known in the art. The laser  106 , in the embodiment shown in  FIG. 3 , is butt coupled to the slider  104  in the manner discussed below with reference to  FIG. 4A . As shown, the laser  106  is thermally-coupled to a tab  120 , which extends upwardly from the flexure  102 . 
         [0025]    While the present invention is explained in terms of a laser, other thermal energy sources can replace the laser and fall within the scope of the invention. In one embodiment, the laser  106  is a laser diode, such as, for example, the 10 mW laser diode manufactured and sold by Semco Laser Technology of Baldwin Park, Calif. Any other laser diode known in the art may also be used in the present invention. In one embodiment, a laser diode having a power rating of from about 1 to about 25 mW is used. In another embodiment, a laser diode having a power rating of from about 8 to about 15 mW is used. In one embodiment, the laser provides sufficient power to heat the magnetic media to or above its Curie point. The laser diode may have an anode and a cathode for electrically coupling the laser diode to a power source. 
         [0026]    Considerations for selecting and mounting the laser  106  include its power rating, ease of coupling to a waveguide, effect on slider flying characteristics, and thermal dissipation. The laser  106  should be able to generate sufficient power to reduce the coercivity of the recording medium. The laser  106  should be mounted to the flexure  102  in a manner that allows dissipation of heat. In the embodiment of  FIG. 3 , the laser  106  includes two heat transfer surfaces. One full face is in thermal contact with the tab  120  of the flexure  102  and another face is in thermal contact with the slider  104 . 
         [0027]    As shown in  FIGS. 4A and 4B , a slider  104  includes a disk opposing face  110  and a top face  111  bounded by a leading face  112 , a trailing face  114 , and side faces  116  extending from the leading face  112  to the trailing face  114 . The shape and contours of the disk opposing face  110  determine the flying characteristics of the slider  104 . The slider  104  must maintain adequate roll, pitch, and normal stiffness over the concentric data tracks of the recording medium.  FIGS. 4A and 4B  further show the location of the transducing head  118 , which is positioned on the trailing face  114  near the disk opposing face  110 . 
         [0028]      FIGS. 4A and 4B  show embodiments in which the laser  106  is vertically disposed on the slider  104 . In other words the laser  106  emits light directly into the entrance to the waveguide  126 . The laser  106 , in the embodiment shown in  FIG. 4A  is butt coupled to the top face  111  and secured with any known technique, including by use of an adhesive. As shown, the laser  106  is configured such that the light-emitting center portion of the laser  106  is aligned with the waveguide  126 . Any known active alignment technique can be used to optimize alignment of the laser  106  with the waveguide  126 . The top portion or entrance of the waveguide  126  includes an optical grading, which directs the light into the waveguide  126 . In another embodiment, the laser  106  is free space coupled to the waveguide  126 . In other words the laser  106  is mounted above the entrance of the waveguide  126  located on the slider  104 . 
         [0029]    In the embodiment of  FIG. 4B , the laser  106  is mounted to the trailing face  114 , which places one full face of the laser  106  in contact with the slider  104 . In the embodiment shown, the laser  106  is set into a pocket formed in the trailing face  114  by a known technique such as ion milling. This configuration can provide additional stability and assist with proper alignment of the laser  106  with the waveguide  126 . Again, active alignment can be used to optimize alignment of the laser  106  with the waveguide  126 . 
         [0030]    The waveguide  126  may be fabricated from any material known in the art capable of transmitting or conducting the laser beam from the laser source to a position near the write portion of the transducing head. The waveguide  126  is sized and shaped in any manner known in the art to conduct the laser beam effectively. The waveguide  126  may be constructed from one material or from multiple materials. The waveguide  126  can include one or more condensing or transducing elements to assist in directing the light to the write gap to effectively heat the magnetic media. 
         [0031]      FIGS. 5A and 5B  show a perspective view and a sectional perspective view of a portion of the transducing head  118 , according to one embodiment of the present invention. The transducing head  118  is formed near the lower edge of the trailing face of the slider  104 . As shown in  FIGS. 5A and 5B , the transducing head  118  includes a first pole  130 , a second pole  132 , and a read/write coil  134 . An optical path or waveguide  126  extends from at or near the top face of the slider  104  to near the write gap  40 . As shown, the waveguide  126 , in this embodiment, extends along a front face of the first pole  130 . The read/write coil  134  extends along a front face of the first pole  130  and behind the second pole  132 . The read/write coil  134  travels between the waveguide  126  and the second pole  132 . The read/write coil  134  is insulated from the poles  130 ,  132  by an insulating layer. 
         [0032]    As further shown in  FIG. 5A , the second pole  132  includes a twin, or split, back gap through which the waveguide  126  travels. This configuration allows the waveguide  126  to extend to a point near the write gap  40  of the transducing head  118 , without requiring any bending or turning of the waveguide  126 . As shown in  FIG. 5A , the second pole  132  includes a first closure  44  and a second closure  46 . The closures  44 ,  46  act to strengthen the magnetic circuit conducted by the first pole  130  and the second pole  132 , which reduces the magnetic reluctance and the power that must be supplied by the coil  134 . This, in turn, increases the write efficiency of the head. Various other closed back gap configurations can also be used, which allow the waveguide  126  to travel to the distal end of the transducing head  118 , without bending or turning. In one embodiment of the present invention, the closures  44 ,  46  are not present. In this open back gap configuration, the opposing pole areas must be sufficiently large to reduce the magnetic reluctance relative to the write gap  40 . For example, in one embodiment the opposing area of the back gap is from about  10  to about  100  times larger than the opposing area of the write gap  40 . 
         [0033]    As shown in  FIGS. 5A and 5B , the waveguide  126  terminates at a termination point  48  near a distal end of the transducing head  118 . An optical condenser or transducer (not shown) is typically coupled to the termination point  48  of the waveguide  126  to direct the light into the write gap  40 . According to another embodiment of the present invention, the waveguide  126  travels between the coil  134  and the second pole  132 . 
         [0034]      FIGS. 6 ,  7 A, and  7 B show various head/gimbal or load beam assemblies for mounting or coupling a laser source to the disclosed waveguide.  FIG. 6  is a perspective view of a head/gimbal assembly  130 , according to another embodiment of the present invention. As shown in  FIG. 6 , the head/gimbal assembly  130  includes a gimbal or flexure  132 , a slider  134 , and a laser source  136 . The assembly  130  can be mounted to any load beam known in the art. As shown in  FIG. 6 , the assembly  130  further includes one or more tabs  138  projecting upward from the flexure  132 . The tabs  138  may be integrally formed from the flexure  132  or may be coupled to the flexure  132 . The embodiment shown in  FIG. 6  includes four heat transfer surfaces to accomplish cooling of the laser source  136 . In the embodiment of  FIG. 6 , the beam from the laser source  136  is turned ninety-degrees, using any known technique, to direct the beam in a direction generally perpendicular to the major plane of the slider  134 . For example, a forty-five degree mirror  139  could be positioned between the output of the laser and the input of the waveguide. 
         [0035]      FIG. 7A  is a sectional view and  FIG. 7B  is a perspective view of a slider  140 , according to yet another embodiment of the present invention. In this embodiment, the laser source (not shown) is located somewhere upstream (i.e., off board) from the slider  140  and the light from the laser source is carried to the slider  140  by an optical fiber  146 . The assembly  140  can be mounted to a head/gimbal assembly, which can in turn be mounted to any load beam known in the art. The optical fiber  146  can be any fiber, as known in the art, capable of conducting the laser beam from the laser source to a location near the trailing edge of the slider  140 . For example, the optical fiber  146 , in one embodiment, is  80  micron RC SMF  28  Corning fiber or any other single-mode multi-mode fiber commercially available, including plastic optical fiber. In one embodiment, the optical fiber  146  could be covered with a protective coating or buffer. 
         [0036]    As shown in  FIGS. 7A and 7B , the slider  140  includes a slider base  148  and a top  150 . A focusing ball  152  is located adjacent a distal end of the optical fiber  146  and focuses light exiting the optical fiber  146  toward a forty-five degree coupling surface or mirror  154 . The coupling mirror  154  directs the light beam  156  into the entrance to the waveguide  126 . Again, the entrance to the waveguide  126  includes an optical grading that collects light and focuses it along the waveguide  126 . This structure is also commonly referred to as a silicon optical bench. 
         [0037]    Although the present invention has been described with reference to preferred embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.