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 element for writing information onto magnetic media, a read head element for reading information from the magnetic media, and an electromagnetic field shield element that is disposed between the write head element and the read head element. The shield functions to shield the read head from electromagnetic field energy created by the write head element. An enhanced second embodiment includes an electrical circuit element that is disposed proximate the read head element that functions to generate an electromagnetic field at the read head element that is generally oppositely directed to the electromagnetic field generated by the write head element to reduce the total electromagnetic field that the read head element is exposed to during a writing operation. The method for operating the read/write head in a hard disk drive, includes the steps of writing data onto a hard disk and reading data from the hard disk simultaneously with the data writing. This is accomplished by shielding the read head from the electromagnetic field energy generated during the data writing by utilizing the electromagnetic field shield element that is disposed between the write head element and the said read head element. The electrical circuit element of the second embodiment is preferably interconnected with the write head electric circuit.

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 shielding and 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 element and the MR element are specially-made structures on the read/write head consisting of layers of specially-deposited thin films. The MR element layers are typically deposited onto the substrate first, and the inductive-element layers are deposited after the deposition of the MR element. Significantly, the write head element and the read head element cannot operate at the same time due to interference of the electromagnetic field generated by the write signal with the read-back signal. In other prior art devices the inductive element layers are deposited first and the MR element layers are deposited after them. However, interference between the write signal and the read-back signal still exists, and these devices also cannot simultaneously write to and read from the disk. 
     There are significant uses in the industry for a read/write head that has the ability to simultaneously write data to a disk and read data from a disk. However, prior art read/write heads cannot perform this task due to the write signal electromagnetic field interference described above. There is therefore a need for a read/write head wherein the writing function and reading function can be simultaneously performed. 
     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 element for writing information onto magnetic media, a read head element for reading information from the magnetic media, and an electromagnetic field shield element that is disposed between the write head element and the read head element. The electromagnetic field shield functions to shield the read head from electromagnetic field energy created by the write head element to reduce the total electromagnetic field that the read head element is exposed to during a writing operation. An enhanced second embodiment includes an electrical circuit element that is disposed proximate the read head element that functions to generate an electromagnetic field at the read head element that is generally oppositely directed to the electromagnetic field generated by the write head element. The method for operating the read/write head in a hard disk drive, includes the steps of writing data onto a hard disk and reading data from the hard disk simultaneously with the data writing. This is accomplished by shielding the read head from the electromagnetic field energy generated during the data writing by utilizing the electromagnetic field shield element that is disposed between the write head element and the said read head element. The electrical circuit element of the second embodiment is preferably interconnected with the write head electric circuit. 
     It is an advantage of the present invention that the functions of writing data and reading data can be simultaneously performed. 
     It is another advantage of the present invention that the electromatic field shield element shields the read head from the electromagnetic field generated by the write head element, such that signal interference of the read head element is minimized. 
     It is a further advantage of the present invention that an interference reduction electrical circuit element may be disposed proximate the read head element to generate an electromagnetic field that interferes with an electromagnetic field from the write head element. 
     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 a further advantage of the present invention that an improved slider having the improved read/write head disposed thereon, and an improved hard disk drive 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. 
    
    
     BRIEF DESCRIPTION OF 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 read/write head according to a first embodiment of the present invention, taken along lines  2 — 2  of FIG. 1; 
     FIG. 3 is an elevational view of the read/write head depicted in FIG. 1 having cut-away portions; 
     FIG. 4 is a perspective view of the read/write head depicted in FIG. 3 with further cut-away portions to better depict the invention; 
     FIG. 5 is a side cross-sectional view of a read/write head according to a second embodiment of the present invention that is similar to the view depicted in FIG. 2; 
     FIG. 6 is an elevational view of the embodiment of the read/write head depicted in FIG. 5 having cut-away portions and being similar to the view depicted in FIG. 3; and 
     FIG. 7 is a perspective view of the read/write head depicted in FIG. 6 having further cut-away portions to better depict the invention, and being similar to the view depicted in FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In this invention, a magnetic recording head with novel, advantageous structural features is described. A first significant feature is that the inductive write head is deposited first onto the substrate, and the MR read head is deposited after the deposition of the inductive element. When this type of head is used in a hard disk drive, the written area of the hard-disk will pass underneath the read head immediately after passing under the write head, thereby facilitating almost immediate read-after write. This immediate read-after-write can offer significant advantages in magnetic recording systems. Secondly, a write/read electromagnetic field shield layer is deposited after the deposition of the inductive write head and before the deposition of the MR read head. With this shield layer, the recording write head can write onto the hard disk and the MR read head can read back from the hard disk simultaneously. This simultaneous write/read capability is very useful during magnetic recording. Thirdly, to further reduce the interference between the write head and the read head, an interference reduction 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 interference reduction element, the net electromagnetic field generated from the write head and the interference reduction element is significantly reduced at the MR element of the read head. The inductive write head structure and the MR 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, the 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 typically 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 . Fly height tends to decrease with increasing recording density requirements; therefore, near-contact and contact recording are being explored for future application in disk drives. The present invention can also be used beneficially in drives using near contact and contact recording, since the benefits obtained are not dependent on flying height. The novel features of the present invention are best understood in conjunction with FIGS. 2,  3  and  4  as are next discussed. 
     FIG. 2 is a side cross-sectional view of the read/write head  10  taken along lines  2 — 2  of FIG. 1, FIG. 3 is an elevational view of the read/write head  10  having cut-away portions to depict the internal components thereof, and FIG. 4 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,  3  and  4 , the read/write head  10  generally includes an inductive write head  40  that is formed on the rearward surface  14  of the slider  18 , an electromagnetic field shield  44  that is formed on the outward side of the write head  40 , and a magnetoresistive (MR) read head  48  that is formed on the outward side of the electromagnetic field shield  44 . 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 , shield  44  and read head  48 , 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 relatively narrow pole tip  80 . A pole 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 tips  80  and  98  of the first and second pole pieces respectively by a gap forming piece  108  formed on the pole tip  80  of the first pole piece  60 . The width (W) of the gap forming piece  108  determines the width of the data writing track. 
     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 circular, 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 is  10  direct the lead  144  out of the plane of the induction coil  120  and towards the external electrical connection terminals  156 . 
     Inductive writing heads are known in the prior art to have shapes and sizes that differ from the embodiment of write head  40  described herein, and the present invention is intended to not be limited to the characteristics of the preferred embodiment of the write head  40  described herein. 
     After the deposition of an insulation layer  157 , the electromagnetic field shield element  44  is next deposited on the outward side of the write head  40 . The shield  44  is generally circular in shape in order to provide a shield for the generally circular, spiral induction coil  120 , and the diameter of the shield  44  is generally at least as large as the diameter of the induction coil  120 . The shield  44  is disposed between the coil  120  and the MR read head  48  such that the MR read head  48  is shielded from the electromagnetic field of the induction coil  120 . Conceivably, the shield diameter could be less than the diameter of the induction coil where effective shielding is still maintained; furthermore, where the shape of the induction coil is other than a generally circular shape, the shield will advantageously, although not necessarily, adopt the same shape as the induction coil. Basically, the shape of the shield  44  is a secondary consideration to its primary role of providing an effective electromagnetic field shield for the read head  48 . 
     A lower portion  158  of the shield  44  preferably extends between the write head pole tip  98  and the MR read head, to shield the MR read head from the intense electromagnetic field at the write head gap  104 . The electromagnetic field shield  44  is preferably composed of a non-magnetic, electrically conductive material, such as copper or gold, although other materials may prove equally suitable. To avoid corrosion problems, particularly where the shield is composed of copper, an adequate thickness of insulator material  160  is formed across the lower end  166  of the shield  44 . The shield  44  does not require any electrical connection in order to perform its shielding function. As will be understood by those skilled in the art, the thickness of the shield  44  is preferably at least skin depth. Skin depth refers to a thickness of conductive material that is sufficient to absorb the electromagnetic field energy that interacts with it, and skin depth is related to the permeability and conductivity of the material that comprises the shield  44 , as well as the operating frequency of the electromagnetic energy that interacts with it. Formulas for determining skin depth are known to those skilled in the art. In the preferred embodiment of the present invention, the shield  44  is composed of copper having a thickness in the range of from approximately 0.5 microns to approximately 25 microns, with a preferred thickness of approximately 10 microns. 
     Following the formation of the shield element  44 , an insulator layer is deposited and 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 first magnetic shield  180  and a second magnetic shield  188  and a magnetoresistive (MR) element  192  disposed therebetween. The width  194  of the MR element  192  is preferably significantly 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  194  of the MR element  192  is from approximately the width (W) of the gap forming piece  108  to approximately {fraction (1/10)} of the width (W) of the gap forming piece  108 . The distance between the write head  40  and read head  48  varies from approximately 1.5 microns to approximately 35 microns depending upon the thickness of the electromagnetic field shield  44 , the insulation layers and the MR element first magnetic shield  180 . 
     As indicated hereabove, the manufacturing process for the read/write head  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 MR 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 . 
     The electromagnetic field shield  44  is a significant feature of the present invention in that it allows the write head  40  and the read head  48  to function simultaneously. That is, the read/write head  10  of the present invention may be utilized to write data on a track and simultaneously read data from the same track because the electromagnetic field shield  44  substantially eliminates electromagnetic interference between the write head electromagnetic fields and the read head which seeks to detect the magnetic fields of the media passing thereunder. Thus, while prior art devices have included a write head disposed in front of a read head, the two heads  40  of such devices do not effectively function simultaneously because of the interference that the electromagnetic fields of the write head cause to the read head. Thus, the read/write head  10  of the present invention can be utilized to write data and nearly immediately thereafter read the data to verify it in an ongoing process such that the write head and read head are operating simultaneously. 
     A read/write head  200  according to a second embodiment of the present invention is depicted in FIGS. 5,  6  and  7 , wherein FIG. 5 is a side cross-sectional view of the read/write head  200  that is similar to the view depicted in FIG. 2, FIG. 6 is a plan view that is similar to the view depicted in FIG. 3, and FIG. 7 is a perspective view that is similar to the view depicted in FIG.  4 . As will be understood from the following description, the read/write head  200  of the second embodiment possesses many of the same elements as are found in the read/write head  10  of the first embodiment, and identical numerals are utilized to identify identical structural elements. The novel additional feature of the read/write head  200  of the second embodiment comprises the placement of an electrically conductive circuit line element  204  behind the read head  48  to provide an electromagnetic field which interferes with and reduces the electromagnetic field at the read head MR element  192  that is caused by the write head and not absorbed by the electromagnetic field shield  44 , as is next described. 
     As depicted in FIGS. 5,  6  and  7 , the read/write head  200  includes an inductive write head  40  that is disposed proximate the rear surface  14  of the slider  18 . An electromagnetic field shield  44  is disposed behind the write head  40  and a read head  48  is disposed behind the shield  44 . An electrically conductive circuit line element  204  is deposited behind the read head  48  such that a layer of insulation separates the conductive line element  204  from the second magnetic shield  188  of the read head  48 . The conductive line element  204  is deposited proximate the MR element  192 , and a sufficient thickness of insulator material  208  may be disposed beneath the element  204  to prevent corrosion problems, particularly where the element  204  is composed of copper. 
     Electrical power for the element  204  is provided through the induction coil circuitry. That is, the electrical line  144  from the inner end  148  of the induction coil is routed through the electrical conductive line element  204 , in distinction to its routing in the read/write head embodiment  10  as is best depicted in FIG.  4 . Particularly, as is best seen in FIG. 7, the electrical lead  144  is fed through vias  152  around the shield  44  and outwardly to the substrate layer that includes the electrical conductive line element  204 . The electrical lead  144  passes through the conductive line element  204  and thence inwardly and upwardly to its outer terminal connection  156 . An important feature of the read/write head  200  is that no new electrical connections or additional read/write head terminals are required to obtain the performance enhancement provided by the electrical circuit element  204 . This is because the electrical lead  144  of the induction coil  120  is routed through the conductive line element  204  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 element  204 , such that it creates a small electromagnetic field by its passage through the conductive line element  204 . Furthermore, as will be understood by those skilled in the art, owing to the direction of the electrical current through the conductive line element  204 , the electromagnetic field generated by the conductive line element  204  is directed oppositely to the electromagnetic field that is generated by the write head. That is, with specific regard to the location of the MR element  192 , where the write head  40  (according to the right hand rule) creates a generally downward electromagnetic field at the MR element  192 , the conductive line element  204  creates a generally upward electromagnetic field; whereby the electromagnetic field of the conductive line element  204  acts to interfere with and cancel the effects of the electromagnetic field generated by the write head  40 . Thus, where the electromagnetic field shield  44  imperfectly blocks the effects of the electromagnetic field generated by the write head  40 , the conductive line element  204  generates an interfering electromagnetic field that acts to cancel the effect of the write head electromagnetic field upon the MR element  192 . The conductive line element  204  in the read/write head embodiment  200  therefore enhances the ability of the write head  40  and the read head  48  to function simultaneously and with reduced interference, such that the read/write head  200  is able to write and read simultaneously. 
     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 spirit and scope of the invention.