Abstract:
The present invention is a read/write head for writing information to magnetic media and reading information from magnetic media. It includes a write head for writing information onto magnetic media, a read head for reading information from the magnetic media, and an electrical circuit element that is disposed proximate the read head that functions to generate an electromagnetic field at the read head that is generally oppositely directed to the electromagnetic field generated by the write head. The method for operating the read/write head in a hard disk drive, includes the steps of writing data onto a hard disk, while simultaneously generating an electromagnetic field at the read head that is directed oppositely to the electromagnetic field generated by the write head.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to read/write magnetic head assemblies, and more particularly to devices for canceling unwanted electromagnetic fields within such heads. 
     2. Description of the Prior Art 
     In a conventional hard-disk drive (HDD) utilizing so-called MR heads as the recording transducer, the recording head typically uses different elements on the head to perform the write and read operations. Writing on the hard-disk is typically performed using an inductive writing head element, and reading back from the hard-disk is typically performed using a read head having a magnetoresistive (MR) element. The inductive write head and the MR element are specially-made structures on the read/write head consisting of layers of specially-deposited thin films. The read head is typically deposited onto the substrate first, and the write head layers are deposited after the deposition of the read head. In other prior art devices the write head layers are deposited first and the read head is deposited after them. In either head configuration significant problems occur because the electromagnetic field generated by the write head can adversely affect the operation of the read head by biasing the MR element. Where the MR element has become biased by exposure to the electromagnetic field of the write head, it produces a noisy signal that ultimately leads to reading errors. A need therefore exists for an improved read/write head wherein the MR element is not exposed to strong electromagnetic fields from the write head. The present invention solves this problem by creating an oppositely directed electromagnetic field at the MR which acts to substantially interfere with and cancel the effects of the electromagnetic field generated by the write head. 
     SUMMARY OF THE INVENTION 
     The present invention is a read/write head for writing information to magnetic media and reading information from magnetic media. It includes a write head for writing information onto magnetic media, a read head for reading information from the magnetic media, and an electrical circuit element that is disposed proximate the read head that functions to generate an electromagnetic field at the read head that is generally oppositely directed to the electromagnetic field generated by the write head. The method for operating the read/write head in a hard disk drive, includes the steps of writing data onto a hard disk, while simultaneously generating an electromagnetic field at the read head that is directed oppositely to the electromagnetic field generated by the write head. 
     It is an advantage of the read/write head of the present invention that electromagnetic field biasing of the read head is reduced. 
     It is a further advantage of the present invention that an electromagnetic field generating electrical circuit element is disposed proximate the read head to generate an electromagnetic field that substantially interferes with and cancels the electromagnetic field from the write head. 
     It is yet another advantage of the present invention that an improved read/write head has been developed which utilizes existing manufacturing technology. 
     It is yet another advantage of the present invention that an improved slider having the improved read/write head disposed thereon, and an improved hard disk drive incorporating the improved slider are made possible through the utilization of the present invention. 
     These and other features and advantages of the present invention will become fully understood upon reading the following detailed description of the preferred embodiments which makes reference to the several figures of the drawings. 
    
    
     IN THE DRAWINGS 
     FIG. 1 is a perspective view of a typical hard disk drive slider having a read/write head of the present invention disposed on a rearward surface thereof; 
     FIG. 2 is a cross-sectional view of a first embodiment of a read/write head of the present invention, taken along lines  2 — 2  of FIG. 1; 
     FIG. 3 is a perspective view of the read/write head depicted in FIG. 2 with further cut-away portions to better depict the invention; 
     FIG. 4 is a perspective view of an alternative embodiment of the read/write head depicted in FIG. 2 with cut-away portions to better depict the invention; 
     FIG. 5 is a side cross-sectional view of a second embodiment of a read/write head of the present invention that is similar to the view depicted in FIG. 2; 
     FIG. 6 is a perspective view of the read/write head depicted in FIG. 5 having further cut-away portions to better depict the invention, and being similar to the view depicted in FIG. 3; 
     FIG. 7 is a side cross-sectional view of a further embodiment of a read/write head of the present invention that is similar to the view depicted in FIG. 2; 
     FIG. 8 is a rear elevational view of the read/write head depicted in FIG. 7 having cut-away portions to better depict the invention; 
     FIG. 9 is a perspective view of the read/write head depicted in FIGS. 7 and 8 having further cutaway portions to better depict the invention, and being similar to the view depicted in FIG. 3; 
     FIG. 10 is a perspective view of an alternative embodiment of the read/write head depicted in FIG. 7 having cut-away portions and being similar to the view depicted in FIG. 9; 
     FIG. 11 is a side cross-sectional view of a further embodiment of a read/write head of the present invention that is similar to the view depicted in FIG. 2; 
     FIG. 12 is a side cross-sectional view of yet another embodiment of a read/write head of the present invention that is similar to the view depicted in FIG. 1; 
     FIG. 13 is a side cross-sectional view of yet a further embodiment of a read/write head of the present invention that is similar to the view depicted in FIG.  12 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In this application, a magnetic recording head with novel, advantageous structural features is described. The magnetic recording head includes both a write head and a read head, and it also includes an electrical circuit element. It is known that the operation of a write head can adversely affect a read head disposed proximate thereto, where the electromagnetic field from the write head biases the read head. The biasing interferes with the operation of the read head and causes a noisy output from the read head. In the present invention the electrical circuit element generates an electromagnetic field at the read head which is generally oppositely directed to the electromagnetic field generated by the write head. Therefore, the electromagnetic field generated by the electrical circuit element acts to interfere with and cancel the effects of the electromagnetic field generated by the write head. In manufacturing one embodiment of the present invention, the electrical circuit element can be deposited on top of the read head after the read head deposition is finished. When the writing current is also passed through the electrical circuit element, the net electromagnetic field generated by both the write head and the electrical circuit element is significantly reduced at the read head. The inductive write head structure and the read head structure, as well as the manufacturing processes of these two structures is similar to the conventional manufacturing processes for read/write heads. The detailed features of the invention are next discussed. 
     As depicted in FIG. 1, a read/write head  10  of the present invention is disposed on the rearward surface  14  of a typical slider  18 . As is known in the prior art, such sliders  18  are designed to fly above the surface of a hard disk  22  which rotates in the direction of arrow  26  from the leading surface  30  of the slider  18  towards the rearward surface  14 . The novel features of the various preferred embodiments of the read/write head  10  of the present invention are best understood in conjunction with FIGS. 2 and 3 as are next discussed. 
     FIG. 2 is a side cross-sectional view of a first preferred embodiment of a read/write head taken along lines  2 — 2  of FIG.  1  and FIG. 3 is a perspective view of the read/write head  10  having cut away portions to better depict the components of the present invention. As depicted in FIGS. 2 and 3, the read/write head  10  generally includes an inductive write head  40  that is formed on the rearward surface  14  of the slider  18 , a magnetoresistive (MR) read head  48  that is formed on the outward side of the write head  40 , and an electrical circuit element  54  disposed on the outward side of the MR head  48 . Each of the elements is next discussed in detail. 
     The write head  40  includes a first pole  60  piece that is formed on the rearward surface  14  of the slider  18 . The various elements of the read/write head  10  are manufactured utilizing thin film deposition techniques that are well known in the semiconductor processing industry, and insulator material  66  is deposited between the various active components of the write head  40 , read head  48 , and electrical circuit element  54  as is known to those skilled in the art. The first pole piece  60  of the inductive write head  40  is formed with an enlarged upper section  72  which tapers to a narrow lower section  76  and terminates at its lower end in a pole tip  80 . A pole piece connector element  86  joins the upper end  72  of the first pole piece  60  to the upper end  90  of a second pole piece  94 . The second pole piece  94  is generally formed with the same shape as the first pole piece  60 ; that is, it has an enlarged upper end  90  and a narrowed lower end  96  which terminates in a narrow pole tip  98  having a width  100 . The width  100  of the second pole tip  98  need not be the same as the width of the first pole tip  80 . A writing gap  104  is formed between the lower ends  80  and  98  of the first and second pole pieces respectively by a gap forming piece  108  formed on the first pole piece  60 . The width of the data writing track is determined by the width (W) of the gap forming piece  108 . 
     An induction coil  120  is utilized to create the magnetic field that is focused by the pole pieces  60  and  94 . The induction coil  120  has a generally spiral shape and is formed with lower turn portions  124  that pass between the pole pieces  60  and  94 , and upper turn portions  128  that pass outside of the pole pieces  60  and  94 . To provide electrical power to the induction coil  120 , a first electrical lead  134  is engaged to an outer end  138  of the coil  120  and a second electrical lead  144  is engaged to an inner end  148  of the induction coil  120 . The thin film deposition processing techniques that form the lead  144  may include the formation of vias  152  to direct the lead  144  out of the plane of the induction coil  120  and ultimately to the external electrical connection terminals  156 . 
     Following the formation of the second pole piece  96  the components of the read head  48  are next deposited; the components thereof are known to those skilled in the art. Basically, the read head  48  includes a magnetoresistive (MR) element  162  formed behind the second pole piece  96  which functions as a first magnetic shield element of the read head  48 , and a second magnetic shield element  166  disposed thereafter. The width of the MR element  162  is preferably less than the width (W) of the gap forming piece  108  of the write head  40 , such that the read head  48  will be disposed above the same disk track that the write head  40  is on, even when the read/write head  10  is disposed at a maximum skew angle relative to the track direction, as will be understood by those skilled in the art. In the preferred embodiment, the width of the MR element  162  is from approximately the width (W) of the gap forming piece  108  of the write head to {fraction (1/10)} of the width (W) of the gap forming piece. 
     An electrical circuit element  54 , in the form of a conductive line  54  in this embodiment  10 , is next disposed behind the read head  48  to provide an electromagnetic field which interferes with and acts to reduce and cancel the electromagnetic field at the read head MR element  162  that is caused by the write head  40 . The conductive line  54  is deposited behind the read head  48  such that a layer of insulation  180  separates the conductive line  54  from the second shield  166  of the read head  48 , and a sufficient thickness of insulator material  188  may be disposed beneath the conductive line  54  to prevent corrosion problems, particularly where the conductive line  54  is composed of copper. 
     Electrical power for the conductive line  54  is preferably provided through the induction coil circuitry. That is, the electrical line  144  from the inner end  148  of the induction coil is routed in series to and through the conductive line  54 . Particularly, the electrical lead  144  is fed through vias  152  and outwardly to the substrate layer that includes the conductive line  54 . The electrical lead  144  passes through the line  54  and thence inwardly through a via  192  and upwardly  196  to its outer terminal connection  156 . An important feature of the device  10  is that no new electrical connections or additional read/write head terminals are required to obtain the performance enhancement provided by the conductive line  54 . This is because the electrical lead  144  of the induction coil  120  is routed through the line  54  and thence to the terminal  156 . 
     It is therefore to be understood that the electrical current that passes through the induction coil  120  to create the electromagnetic field for the write head, also passes through the conductive line  54 , such that it creates a small electromagnetic field by its passage through the line  54 . Furthermore, as will be understood by those skilled in the art, owing to the direction of the electrical current through the conductive line  54 , the electromagnetic field generated by the conductive line  54  at the MR element  162  is directed oppositely to the electromagnetic field that is generated by the write head  40 . That is, with specific regard to the location of the MR element  162 , where the write head  40  (according to the right hand rule) creates a generally downward electromagnetic field at the MR element  162 , the conductive line  54  creates a generally upward electromagnetic field; whereby the electromagnetic field of the conductive line  54  acts to interfere with and cancel the effects of the electromagnetic field generated by the write head  40 . Thus, the conductive line  54  generates an interfering electromagnetic field that acts to cancel the effect of the write head electromagnetic field upon the MR element  162 . The conductive line  54  in the read/write head embodiment  10  therefore acts to eliminate the biasing effect of the write head upon the read head. 
     As indicated hereabove, the manufacturing process for the device  10  involves thin film processing techniques that are known to those skilled in the art. Of particular concern to the creation of an operable device is that the elements of the read head  48  be deposited flat and parallel to each other. To achieve this, the manufacturing method of the present invention preferably includes at least one planarization step. Particularly, as depicted in FIG. 2, a planarization layer  196  (shown in phantom) may be formed subsequent to the deposition of the induction coil  120  and the pole tip piece  108 . Processes such as chemical-mechanical polishing are utilized to form the planarization layer  196 . 
     A first alternative embodiment  210  to the embodiment  10  discussed hereabove is depicted in FIG. 4, which is a perspective view similar to FIG.  3 . In comparing the embodiment depicted in FIG. 4 with embodiment  10  depicted in FIG. 3, it is to be understood that the significant difference between embodiments  210  and  10  is the electrical interconnection of the conductive line  54 . Specifically, the conductive line  54  of embodiment  210  is electrically connected in parallel with the circuitry of the induction coil  120 ; whereas, in the embodiment  10  the conductive line  54  is electrically connected in series with the electrical circuit of the induction coil  120 . Particularly, an electrical circuit  212  is formed through vias  216  and  220  in the deposited layers of the device  210  to electrically connect the conductive line  54  with the terminals  156  of the device  210 . The electrical lead  144  from the inner end  148  of the induction coil  120  is likewise fed to the device terminal  156 . As will be understood by those skilled in the art, it may be necessary to provide an impedance matching component (not shown) within the electrical circuitry  212  of the conductive line  54  to match the impedance of the induction coil  120 . It is to be understood that other components and elements of the embodiment  210  are structurally identical to those of embodiment  10  as described hereabove. 
     Another embodiment  240  of the present invention is depicted in FIGS. 5 and 6, wherein FIG. 5 is a side cross-sectional view, similar to FIG. 2, and FIG. 6 is a perspective view, similar to FIG.  3 . The significant difference between embodiment  240  and embodiment  10  is that an electrical circuit element in the form of three generally parallel conductive lines  248  are utilized in embodiment  240  in place of the single electrical circuit conductive line  54  of embodiment  10 . The three conductive lines  248  are electrically connected in parallel, relative to each other, and they provide a differently shaped electromagnetic field than the single conductive line  54  of embodiment  10 . However, the electromagnetic field created by the three conductive lines  248  is still directed oppositely to the electromagnetic field at the MR element  162  that is generated by the write head  40 . That is, with specific regard to the location of the MR element  162 , where the write head  40  (according to the right hand rule) creates a generally downward electromagnetic field at the MR element  162 , the three conductive lines  248  create a combined generally upward electromagnetic field; whereby the electromagnetic field of the conductive lines  248  acts to interfere with and cancel the effects of the electromagnetic field generated by the write head  40 . Thus, as with embodiment  10 , the conductive lines  248  generate an interfering electromagnetic field that acts to cancel the biasing effect of the write head electromagnetic field upon the MR element  162 . Additionally, and alternatively, it is to be understood that while the three conductive lines  248  are electrically interconnected in series with the induction coil  120 , as is the single conductive line  54  of embodiment  10 , depicted and described hereabove, it is to be understood that the three conductive lines  248  can be electrically interconnected in parallel with the induction coil  120 , as is done in embodiment  210 , depicted in FIG.  4  and described hereabove. 
     Yet another embodiment  260  of the present invention is depicted in FIGS. 7,  8  and  9 , wherein FIG. 7 is a side cross-sectional view, similar to FIG. 2, FIG. 8 is a rear elevational view with cutaway portions, and FIG. 9 is a perspective view similar to FIG.  3 . The significant difference between embodiment  260  and the preceding embodiments  10  and  240  is that the electrical circuit element  54  and  248  respectively is replaced with an electrical circuit element shaped in a coil configuration  268 . Particularly, as depicted in FIGS. 7-9, the electrical circuit element  268  is formed as a generally flat spiral, similar to the induction coil  120  but smaller in size. The circuit element  268  is electrically interconnected within the device  260 , such that the electromagnetic field generated by the circuit element  268  at the MR element  162  is directed oppositely to the electromagnetic field that is generated by the write head  40 . That is, with specific regard to the location of the MR element  162 , where the write head  40  (according to the right hand rule) generates a generally downward electromagnetic field at the MR element  162 , the circuit element  268  creates a generally upward magnetic field at the MR element, whereby the electromagnetic field of the circuit element  268  acts to interfere with and cancel the effects of the electromagnetic field generated by the write head  40 . Thus, the circuit element  268  generates an interfering electromagnetic field that acts to cancel the biasing effect of the write head electromagnetic field upon the MR element  162 . It is to be noted that the electrical circuit element  268  is electrically interconnected in series with the induction coil  120 . That is, the electrical line  144  from the inner end  148  of the induction coil  120  is routed in series to and through the electrical circuit element  268 . Particularly, the electrical lead  144  is fed through a via  152  and outwardly to the substrate layer that includes the electrical circuit element  268 . The electrical lead  144  passes through the electrical circuit element  268  and thence inwardly through vias  272  and  276 , and upwardly  280  to the outer terminal connection  156 . 
     Yet a further embodiment  290  of the present invention is depicted in FIG. 10 which is a perspective view similar to FIG.  9 . As will be understood by those skilled in the art, the significant difference between embodiment  290  and embodiment  260  is that the electrical circuit element  268  of embodiment  290  is electrically interconnected in parallel with the induction coil  120 ; whereas the electrical circuit element  268  of embodiment  260  is electrically interconnected in series. Specifically, the electrical circuitry  294  passes through vias  296  to the substrate layer that includes the electrical circuit element  268  and through vias  272  and  276  to the outer terminal connection  156 . As with previously described electrically parallel interconnections, it may be necessary to include impedance matching elements within the electrical circuit  294 . 
     A further embodiment  310  of the present invention is depicted in FIG. 11, which is a side cross-sectional view, similar to FIG.  2 . The significant difference between embodiment  310  depicted in FIG.  11  and embodiment  10  depicted in FIG. 2, is that the location of the read head  48  and the write head  40  is reversed, and the electrical circuit element  312  is disposed inwardly of the read head  48 , but still on the opposite side of the read head  48  relative to the write head  40 . 
     Specifically, as depicted in FIG. 11, the electrical circuit element comprises a conductive line  312  that is first deposited upon the flat rear surface  14  of the slider  18 , and insulator material  314  is deposited to electrically insulate the conductive line  312 . Thereafter, a planarized surface  318  (shown in phantom) is preferably formed prior to the deposition of a first read head magnetic shield piece  322 , such that a flat deposition surface for the shield  322  is created. Following the deposition of the first read head shield  322 , the further components of the read head  48  and write head  40  are deposited utilizing well known semiconductor processing techniques. As with the previously described preferred embodiment  10 , the conductive line  312  is electrically interconnected within the device  310 , such that the direction of the electrical current through the conductive line  312  creates an electromagnetic field at the MR element  162  that is directed oppositely to the electromagnetic field that is generated by the write head  40 . That is, with specific regard to the location of the MR element  162 , where the write head  40  (according to the right hand rule) creates a generally downward electromagnetic field at the MR element  162 , the conductive line  312  creates a generally upward electromagnetic field; whereby the electromagnetic field of the conductive line  312  acts to interfere with and cancel the effects of the electromagnetic field generated by the write head  40 . Thus, the conductive line  312  generates an interfering electromagnetic field that acts to cancel the biasing effect of the write head electromagnetic field upon the MR element  162 . It is to be understood, with consideration of the preferred embodiments  10  and  210  depicted and described hereabove, that the conductive line  312  is substantially identical to the conductive line  54 , and it can be electrically interconnected in series or in parallel with the induction coil of the write head  40 . 
     Still a further embodiment  340  of the present invention is depicted in FIG. 12, which is a side cross-sectional view similar to FIGS. 5 and 11. The significant difference between embodiment  340  and embodiment  310  is that the conductive line  312  of embodiment  310  is replaced with an electrical circuit element comprising three conductive lines  348 . In this regard, embodiment  340  is similar to embodiment  310  in the same way that embodiment  240  is similar to embodiment  10 . Specifically, the three conductive lines  348  are deposited in a first layer upon the surface  14  of the slider  18 . Thereafter, a planarized surface  352  (shown in phantom) is created and the read head  48  followed by the write head  40  are formed thereon. As will be understood by those skilled in the art upon having read and understood the description of embodiment  240  set forth hereabove, the three conductive lines  348  may be electrically interconnected with the induction coil  120  of the write head  40  in series or in parallel. The significant feature of the electrical interconnection of the three conductive lines  348  is that the direction of the electrical current through the conductive lines  348  must be such that the electromagnetic field generated by the conductive lines  348  at the MR element  162  is directed oppositely to the electromagnetic field generated by the write head  40 . Thus, the conductive lines  348  generate an interfering electromagnetic field that acts to cancel the biasing effect of the write head electromagnetic field upon the MR element  162 . 
     Still a further embodiment  360  of the present invention is depicted in FIG. 13, which is a side cross-sectional view that is similar to FIGS. 12 and 7 depicted and described hereabove. The significant difference between embodiment  360  depicted in FIG.  13  and embodiment  340  depicted in FIG. 12 is that embodiment  360  includes a generally spiral electrical circuit element  366  that is similar to the spiral electrical circuit element  268  depicted in FIGS. 7,  8  and  9  and described in detail hereabove. Specifically, electrical circuit element  366  is formed as a flat spiral element, generally similar to spiral element  268 , and is formed on the outer surface  14  of the slider body  18 . A planarized surface  372  (shown in phantom) is preferably formed thereafter, and the read head  48 , followed by the write head  40  are thereafter deposited to form the embodiment  360 . As with the circuit element  268  of embodiment  260 , it is important that the direction of the electrical current through the circuit element  366  be directed such that the electromagnetic field generated by the circuit element  366  at the MR element  162  is directed oppositely to the electromagnetic field that is generated by the write head  40 ; whereby the electromagnetic field of the circuit element  366  acts to interfere with and cancel the biasing effects of the electromagnetic field generated by the write head  40 . It is to be further understood that the electrical circuit element  366  may be electrically connected in the device  360  in series with the induction coil of the write head  40  or in parallel therewith. 
     While the present invention has been shown and described with regard to certain preferred embodiments, it will be understood by those skilled in the art upon comprehending the preceding disclosure that certain alterations and modifications in form and detail may be made therein. It is therefore intended by the inventors that the following claims cover all such alterations and modifications that nevertheless include the true sprit and scope of the invention.