Abstract:
A disk storage unit includes an electro-magnetic slider which has a contact detecting function. The unit includes a rotating recording disk, a slider body having a head for reading and writing information with respect to the recording disk, a suspension for supporting the slider body in such a manner that the slider body is opposed to the recording medium and flies above recording medium with a small gap therebetween owing to an air flow generated by a rotation of the recording disk. The suspension, on which the slider is mounted, has an electric resistance pattern formed on the suspension for detecting a strain generated on the resistance pattern when the slider body comes into contact with the disk recording medium.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a structure of a head used for a disk storage unit such as a magnetic disk storage unit, magneto-optical disk storage unit and optical disk storage unit. More particularly, the present invention relates to a head slider and a disk storage unit having a function of detecting that a head comes into contact with a disk recording medium, in which the head flies above a surface of a rotating disk recording medium with a minute distance so that information can be read from the disk recording medium and also information can be written to the disk recording medium. 
     2. Description of the Related Art 
     Magnetic disk storage units have been used as external storage units for information processors. Recently, there has been a demand for an increase in the recording density of the magnetic disk storage unit in accordance with an increase in the quantity of information to be recorded. When information is recorded in a magnetic disk storage unit at high density, it is indispensable to operate the magnetic disk storage unit in such a manner that a magnetic recording head rises a minute distance above a recording medium. Further, it is necessary that the magnetic recording head is made to slide on the recording medium under the condition that a very light load is given to the recording medium by the magnetic recording head. 
     In a magnetic recording head structure, as a load given to the recording medium by the magnetic recording head is very small and the size of the structure is reduced, there has been proposed a micro-contact type thin film magnetic recording head which is a thin film magnetic recording head assembling body in which a thin film magnetic recording head is combined with an elastic supporting member. In this micro-contact type thin film magnetic recording head, there are provided an electro-magnetic transducer having a medium contact surface formed by the thin film forming technique, and a long slender plate-shaped flexible supporting body having a signal lead pattern and supporting the electro-magnetic conversion element section. 
     This micro-contact type thin film magnetic recording head is very small, and it is difficult to make the medium contact surface of the electro-magnetic transducer come into contact with the recording medium surface in a good contacting and sliding condition. Accordingly, there is a tendency that the recording and regenerating characteristic of the thin film magnetic recording head is deteriorated. For the above reasons, there is a necessity for a micro-contact type thin film magnetic recording head which can be easily controlled in such a manner that the medium contact surface of the electro-magnetic transducer contacts with the recording medium surface in a good contacting and sliding condition. 
     A support mechanism for the conventional magnetic recording head includes: a slider on which the magnetic recording head is mounted; a suspension for holding the slider; a load beam for holding the suspension; and a spacer for holding the load beam. The load beam is composed of a rigid portion and an elastic portion. The elastic portion of the load beam is subjected to machining referred to as “R-bending” so that a load can be generated by the elastic portion in order to urge the slider against the recording medium. Due to the above arrangement, the slider can be urged against the recording medium with a predetermined force. When the recording medium (magnetic storage disk) is rotated in the recording and regenerating mode, the load given to the slider is counter-balanced by a rising force generated by an air flow on the slider surface. Therefore, the slider can rise above the recording medium while a minute or small gap is maintained between the slider and the recording medium. 
     When the recording density is increased in the conventional magnetic recording head structure described above, it is necessary to reduce the distance from the disk recording medium to the magnetic recording head slider to as small as possible. On the other hand, although the surface of the disk recording medium is smoothed by machining such as mirror surface machining, there are minute protrusions and irregularities. When the heights of these protrusions and irregularities exceed an allowable range, the magnetic recording head slider collides with the recording medium surface of the disk in the seeking operation. 
     In order to solve the above problems, the conventional magnetic recording head slider is provided with a detecting means for detecting contact between the magnetic recording head slider and the disk recording medium. For example, a piezo-electric element is attached onto a side of the magnetic recording head slider, and a shock caused in the contact of the magnetic recording head slider with the disk recording medium is detected by the piezo-electric element, so that the shock can be picked up in the form of an electric signal. When the contact of the magnetic recording head slider with the disk recording medium is detected in this way, an intense collision of the magnetic recording head with the disk recording medium can be avoided, and data recorded on the recording medium can be safely stored. 
     However, in accordance with the progress of the magnetic disk storage unit, the recording density of which is highly increased, the size of the magnetic recording head slider is reduced. Therefore, it becomes difficult to ensure a sufficiently large space to attach the piezo-electric element used for detecting contact between the magnetic recording head and the recording medium. 
     Japanese Examined Patent Publication No. 6-80577 discloses the following technique. An AE (acoustic emission) sensor is attached to the magnetic recording head. When an elastic wave of strain energy generated in the contact of the magnetic recording head with the disk recording medium surface is emitted in the form of a sound (ultrasonic wave), the acoustic emission sensor detects this sound. However, the following problem may be encountered in this technique. The sensitivity of the acoustic emission sensor is very high and, therefore, a sound emitted in a case other than the collision of the magnetic recording head with the recording medium surface is detected in some cases. In other words, unlike a strain sensor, it is difficult to detect only a physical shock by this acoustic emission sensor. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a recording head structure having a function for detecting contact of the slider with the recording medium even if the size of the slider is reduced in accordance with the size of the disk storage unit. 
     Another object of the present invention is to provide a head slider and a disk unit having contact detecting means which can solve the above-mentioned problems. 
     According to the present invention, there is provided a disk storage unit having a contact detecting means, the unit comprising: a rotating disk recording medium; a slider having a head for reading and writing information with respect to the recording medium; means for supporting the slider in such a manner that the slider is opposed to the recording medium and flies above the recording medium with a small gap therebetween due to an air flow generated by the rotation of the recording medium; and the supporting means comprising a suspension on which the slider is mounted, and an electric resistance pattern formed on the suspension for detecting a strain generated on the resistance pattern when the slider comes into contact with the disk recording medium. 
     The electric resistance pattern may be formed on a surface of the suspension on which the slider is mounted. The electric resistance pattern may also be formed on a second surface of the suspension opposite to a first surface thereof on which the slider is mounted. 
     The electric resistance pattern can be formed simultaneously when the suspension is formed. The electric resistance pattern may comprise an electric resistance film adhered to a surface of the suspension. 
     A wiring portion of the electric resistance pattern and another wiring portion electrically connected to terminals of the slider can be formed on the suspension. 
     According to another aspect of the present invention, there is provided an electro-magnetic head slider comprising: a slider body having a head for reading and writing information with respect to a rotating recording medium; means for supporting the slider body in such a manner that the slider body is opposed to the recording medium and flies above the recording medium with a small gap therebetween owing to an air flow generated by the rotation of the recording medium; and an electric resistance pattern formed on the slider body for detecting a strain generated on the resistance pattern when the slider body comes into contact with the disk recording medium. 
     The slider body may have an end surface of an air outflow side thereof with respect to the direction of movement thereof with respect to the rotating recording medium and the electric resistance pattern is formed on the end surface of the slider body. 
     The slider body may have side surfaces thereof with respect to the rotating recording medium and the electric resistance pattern is formed on at least one of the side surfaces of the slider body. The electric resistance pattern is formed at an inside position of the slider body. 
     According to still another aspect of the present invention, there is provided an electro-magnetic head slider comprising: a rotating disk recording medium; a slider body having a head for reading and writing information with respect to the recording medium; means for supporting the slider body in such a manner that the slider body is opposed to the recording medium and flies above the recording medium with a small gap therebetween owing to an air flow generated by the rotation of the recording medium; and an electric resistance pattern formed on the slider body for detecting a strain generated on the resistance pattern when the slider body comes into contact with the disk recording medium; and the slider body having a wiring portion of the electric resistance pattern and another wiring portion electrically connected to terminals of the slider body, the wiring portion being electrically connected to terminals of the slider body. 
     A contact detecting MR element having substantially the same structure as the head element may be used. Such a MR element is formed on the slider body for detecting a thermal asperity generated on the slider body when the slider body comes into contact with the disk recording medium. In this connection, the slider body may have a wiring portion electrically connected to terminals of the MR element, the wiring portion being formed on the suspension on which the slider body is mounted. 
     A thermo-couple may also be used. Such a thermo-couple may be formed at an inside position of the slider body for detecting a strain generated on the slider body when the slider body comes into contact with the disk recording medium. In this connection, the slider body may have a wiring portion of the thermo-couple and another wiring portion electrically connected to terminals of the slider body, the wiring portions being formed on the suspension on which the slider body is mounted. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of a magnetic disk storage unit to which the present invention can be applied, wherein this view shows a state of the magnetic disk storage unit from which an upper cover is removed; 
     FIG. 2 is an enlarged view taken in the direction of arrow “A” in FIG. 1, wherein a head slider section and a supporting section of the magnetic disk storage unit are shown in this view; 
     FIG. 3 is a view showing a mounting portion of the suspension on which the magnetic recording head is mounted; 
     FIG. 4 is a perspective view showing the magnetic recording head slider, wherein this view is taken from the side opposed to the magnetic disk (not shown); 
     FIG. 5 is a perspective view showing the first embodiment of the head structure having a contact detecting function of the present invention; 
     FIG. 6 is a plan view showing a detail of the resistance pattern used as a strain sensor; 
     FIGS.  7 ( a ) and  7 ( b ) are cross-sectional and plan views showing an outline of the resistance pattern; 
     FIGS.  8 ( a ) and  8 ( b ) are cross-sectional views showing a wiring pattern and a land portion; 
     FIG. 9 is a perspective view showing the second embodiment of the head structure having a contact detecting function of the present invention; 
     FIG. 10 is a perspective view showing the third embodiment of the head structure having a contact detecting function of the present invention; 
     FIG. 11 is a perspective view showing the fourth embodiment of the head structure having a contact detecting function of the present invention; 
     FIGS.  12 ( a ) and  12 ( b ) are flow chart of control and block diagram showing an essential structure of the control section; 
     FIG. 13 is a perspective view showing the fifth embodiment of the head structure having a contact detecting function of the present invention; and 
     FIG. 14 is a perspective view showing the sixth embodiment of the head structure having a contact detecting function of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the accompanying drawings, some embodiments of the present invention will be explained in detail as follows. 
     In FIGS. 1 and 2, there is vertically provided a spindle  2  rotated by a spindle motor (not shown) on the base of the disk enclosure  1 . A plurality of magnetic disks  3  are attached to the spindle  2  in such a manner that they are stacked on each other at regular intervals. 
     A head arm  4  is pivoted to the shaft  5  on the base of the disk enclosure  1 . A coil  6  is attached to one rotating end portion of the head arm  4 , and a magnetic recording head slider  20  is attached to the other rotating end portion of the head arm  4  via a suspension  7 . In this connection, the coil  6  is arranged in a magnetic gap of a magnetic circuit formed by the magnets  8 ,  9  and yoke  10 . 
     The magnetic recording head slider  20  is tiltably attached to a flexure portion formed at a front end portion of the suspension  7  as shown in FIG.  2 . In this connection, there is provided an elastic portion  7   a,  which is subjected to R-bending so that it can be bent, only at the base end portion of the suspension  7 . There is provided a flange  7   b  on the side of the intermediate portion of the suspension  7 , so that the rigidity of the suspension  7  can be enhanced, wherein the flange  7   b  is formed by folding. A base end portion  7   c  of the suspension  7  to which the magnetic recording head slider  20  is attached is engaged with an attaching hole  4   a  of the head arm  4  of the magnetic disk storage unit. The suspension  7  is attached to the head arm  4  so that the magnetic recording head slider  20  can be urged against the magnetic disk  3  by a force of the elastic portion  7   a  and a predetermined spring force can be impressed upon the magnetic disk  3 . 
     Movement of the head arm  4  is restricted by inner stopper S 1  and outer stopper S 2 , so that the head arm  4  can be moved in the direction A (and back) between both stoppers. Accordingly, the magnetic recording head slider  20  is moved on the magnetic disk  3  from an inner diameter position to an outer diameter position in a movement range restricted by both stoppers S 1  and S 2 . 
     FIG. 3 is a view showing a supporting mechanism of the magnetic recording head slider  20 . The suggestion  7  is fixed to a spacer  14  of the head arm. The suspension  7  is composed of a slider mounting portion, which is formed as a gimbal portion  22 , and a load beam  21 , and the slider mounting portion and load beam  21  are formed by one integrated sheet member. In this case, it is appropriate to use stainless steel (SUS) as the sheet member. Thickness of the sheet member is approximately 25 μm. The gimbal portion  22  is integrally formed by an opening in a portion of the load beam  21  close to the front end portion. That is, the substantially rectangular gimbal portion  22  is connected to the load beam  21  only at the central portion  31  on the front side of the gimbal portion  22 . The periphery of the gimbal portion  22  is cut off from the load beam  21  by a substantially C-shaped opening  32 . Due to the above structure, the gimbal portion  22  is allowed to move the directions of rolling and pitching with respect to the load beam  21 . 
     That is, the gimbal portion  22  can be deformed in the rolling and the pitching direction with respect to the load beam  21  round the connection section  31  of the gimbal portion  22  with the load beam  21  by the elastic deformation of the connecting section  31 . 
     The size a×b of the slider fixing portion  35 , which is a primary portion of the gimbal portion  22 , is sufficiently large for fixing the magnetic recording head slider  20 , for example, the size a×b of the slider fixing portion  35  corresponds to the outside dimension (a=2 mm and b=1.6 mm) of the magnetic recording head slider  20 . However, as long as the adhesive strength is sufficiently high, this outside dimension may be reduced. In order to ensure the reliability of the apparatus, the weight of the magnetic recording head slider is preferably small. The back side of the slider opposite to the flying surface is flat and fixed to the fixing portion  35  with adhesive. In this case, the center of the slider is made to coincide with the center of the fixing portion  35 . 
     The wiring pattern to be connected to the magnetic recording head slider  20  is arranged as follows. In FIG. 3, reference numerals  51   a  to  51   d  are terminals of the magnetic recording head slider  20 ; reference numerals  52   a  to  52   d  are terminals of the head mounting portion  35  on the load beam  21  side to be connected to the terminals  51   a  to  51   d;  reference numerals  53   a  to  53   d  are wiring patterns formed on the load beam  21 ; and reference numerals  55   a  to  55   d  are terminals to be connected to the outside of the load beam  21 . 
     FIG. 4 is a perspective view of the magnetic recording head slider  20 , wherein this view is taken from the side opposed to the magnetic disk. In this view, reference numerals  41 ,  42 ,  43  are rails, reference numeral  44  is a groove, reference numeral  45  is an inflow end, reference numeral  46  is an outflow end, and reference numeral  47  is an electromagnetic conversion element (MR element). The rail  41  is arranged at the center of the inflow end  45  of the magnetic recording head slider  20 . A pair of rails  42 ,  43  arranged on both sides of the rail  41  extend from the inflow end  45  side to the outflow end  46  side. 
     When the magnetic disk  2  shown in FIG. 1 is rotated and air flows into the magnetic recording head slider  20 , a force to separate the magnetic recording head slider  20  from the magnetic disk  3  is generated on the flying surfaces of the rails  41 ,  42 ,  43 . At the same time, air which has flowed in the direction F from the inflow end  45  side expands into the groove  44 . Therefore, a negative pressure is generated to suck that magnetic recording head slider  20  onto the magnetic disk  3  side. Accordingly, the magnetic recording head slider  20  is raised from the magnetic disk  3  to a height at which forces from both sides counter-balance each other. In this case, the forces include not only the raising force and the sucking force generated by the air current but also the spring force generated by the suspension  7 . 
     When swelling occurs on the rotating magnetic disk  3  or dust adheres to the rotating magnetic disk  3 , the magnetic recording head slider  20  is rotated in the direction of pitching, and the connecting portion  31  of the gimbal portion  22  with the load beam  21  is being bent. The magnetic recording head slider  20  is also rotated in the direction of rolling. As described above, the magnetic recording head slider  24  is supported by the gimbal portion  22  of the suspension  7  so that it can elastically oscillate in both the pitching and the rolling directions. 
     FIG. 5 is a perspective view showing the first embodiment of the present invention. In this embodiment, there is provided a resistance pattern  11  on the back side  35 ′ of the slider mounting portion  35  of the gimbal portion  22  of the suspension  7 . In the case where the magnetic recording head slider  20  comes into contact with the magnetic disk  3 , a strain caused in this slider  20  is detected by the resistance pattern  11 . In this connection, the electric wires  11   a,    11   b  of the resistance pattern  11  are formed on the surface opposite to the surface on which the electric wires  53   a  to  53   d  shown in FIG. 3 of the magnetic recording head slider  20  are formed, and the end portions are connected to the terminals  15   a,    15   b.    
     In this embodiment, the resistance pattern  11 , which acts as a strain gauge, is provided on the back side of the suspension  7  which is opposite to the side on which the slider is mounted. However, in the case where no wiring pattern connected to the magnetic recording head slider  20  is provided on the surface of the suspension  7  as shown in FIG. 3, the resistance pattern  11  may be provided on the same side on which the magnetic recording head slider  20  is mounted. The resistance pattern  11  may be formed on the surface of the suspension  7  in the process of forming the suspension  7 . Alternatively, the resistance pattern  11  may be composed of a resistance film adhering onto the surface of the suspension  7 . 
     When the magnetic recording head slider  20  comes into contact with the surface of the magnetic disk  3 , a minute strain is caused in the suspension  7 , especially in the head mounting portion  35 . This strain is detected by the resistance pattern  11 , and the electric signal of the strain is sent through the wiring patterns  11   a,    11   b  and the terminals  15   a,    15   b  to an appropriate circuit, not shown in the drawing, so that the electric signal can be amplified. In this way, the contact of the magnetic recording head slider  20  with the magnetic disk  3  can be electrically detected. 
     FIG. 6 is a plan view showing the resistance pattern  11  in detail. FIG.  7 ( a ) is a cross-sectional view showing an outline of the resistance pattern  11 , and FIG.  7 ( b ) is a plan view showing an outline of the film-shaped resistance pattern. It is preferable that the resistance pattern  11  acting as a strain gauge is made of CuNi (copper.nickel) alloy, the change in the electric resistance of which is high in the elastic limit when it is deformed. The electric pattern  11  may be formed by the method of the thin film process or adhesion of a film-shaped resistance pattern. 
     According to the method of the thin film process, a polyimide film  24 , which is an insulating film, is formed on the back surface  35 ′ of the slider mounting portion of the suspension  7 ; a large number of steel wire patterns  25  made of CuNi alloy are formed on the polyimide film  24  in parallel with each other; and the terminals are formed into a zigzag shape by bonding with gold balls  26 . On the pattern  25 , there is provided a polyimide film  27  to be used as a protective film. 
     Essentially, the film-shaped resistance pattern  11 ′ has the same structure. As shown in FIG.  7 ( b ), there are provided parallel patterns  25  made of CuNi alloy which are bonded with gold bumps  26 . These patterns  25  are previously formed into a film-shape. These film-shaped patterns are made to adhere onto the back side  35 ′ of the slider mounting portion with an appropriate adhesive agent for polyimide. 
     FIG.  8 ( a ) is a cross-sectional view showing an outline of the wiring pattern  53   a  to  53   d  (shown in FIG. 3) and  11   a,    11   b  (shown in FIG. 5) which are laminated on the suspension  21  of the magnetic disk storage unit by the thin film process, and FIG.  8 ( b ) is a cross-sectional view showing an outline of the terminals (land portions)  52   a  to  52   d  (shown in FIG. 3) which are laminated on the suspension  21  of the magnetic disk storage unit by the thin film process. As illustrated in the drawing, for example, a substrate insulating film  62  of polyimide is formed by the spin-coating method on the base plate  61  of the suspension  21  made of stainless steel of SUS, and then a conductor  63  made of material such as Cu is formed on the substrate  62  by a sputtering method or a vapor-deposition method. In the case of forming a wiring pattern, an upper protective film  65  of polyimide is formed by the spin-coating method on the conductor film  63 , so that the conductor film  63  can be covered. In the formation of the land portion, a pad layer  64  of Au is formed on the conductor  63  by a sputtering method or a vapor-deposition method, and an upper protective film  65  is formed by the spinning coating method and the pad layer  64  is exposed onto the upper side. 
     FIG. 9 is a perspective view of the magnetic recording head slider showing the second embodiment of the present invention. In this embodiment, there is provided a resistance pattern  12  on an end surface on the outflow end  46  side with respect to the moving direction of the magnetic disk  3  of the magnetic recording head slider  20 , and the strain on the slider caused by the contact of the magnetic recording head slider  20  with the magnetic disk  3  is detected by the resistance pattern  12 . This embodiment is preferable when strain is detected in the rolling direction of the magnetic recording head slider  20 . In this connection, four land portions on the suspension  21  side connected to the terminals of the magnetic recording head slider  20  and their wiring sections are formed on the same surface of the suspension  21  by the thin film process in the same manner as that described before. Also, two land portions connected to the terminals of the resistance pattern  12  and their wiring sections are formed on the same surface of the suspension  21  by the thin film process. 
     FIG. 10 is a perspective view of the magnetic recording head slider showing the third embodiment of the present invention. In this embodiment, there is provided a resistance pattern  13  on the side  48  with respect to the moving direction of the magnetic disk  3  of the magnetic recording head slider  20 . In the same manner as that of the embodiment shown in FIG. 6, strain on the slider caused when the magnetic recording head slider  20  comes into contact with the magnetic disk  3  is detected by this resistance pattern  13 . This embodiment is preferable when strain is detected in the pitching direction of the magnetic recording head slider  20 . In this connection, the land portion and the wiring portion can be composed in the same manner as that of the second embodiment. 
     FIG. 11 is a perspective view of the magnetic recording head slider showing the fourth embodiment of the present invention. In this embodiment, there is provided a resistance pattern  49  inside the magnetic recording head slider  20 . The resistance pattern  49  is arranged in a direction perpendicular to the moving direction of the magnetic disk  3  in the same manner as that of the second embodiment shown in FIG.  9 . Therefore, strain in the rolling direction of the magnetic recording head slider  20  can be easily detected. In this connection, the land portion and the wiring portion can be formed in the same manner as that of the embodiment described before. 
     FIG.  12 ( a ) is a flow chart and FIG.  12 ( b ) is a block diagram of the essential structure of the control section when the resistance patterns  11 ,  12 ,  13  and  49  are used as strain sensors as shown in the first to the fourth embodiment so that the contact of the magnetic recording head slider  20  with the magnetic disk  3  can be detected. An abnormal contact of the magnetic recording head (slider) with the magnetic disk is detected by the strain sensor, and the drive of the disk storage unit is stopped. It has been found that the magnetic recording head comes strongly into contact with the magnetic disk after the magnetic recording head has come into contact with the magnetic disk several times, and then the magnetic disk slider starts rubbing the magnetic disk. For the above reasons, it is necessary to stop the drive of the disk storage unit at the initial stage of contact before the magnetic recording head comes strongly into contact with the magnetic disk. 
     Consequently, as shown in FIGS.  12 ( a ) and  12 ( b ), when the strain sensor detects strain and the number of detections of strain reaches a predetermined value, first, the magnetic recording head (slider) is moved to a retracting zone by a voice coil motor (VCM), and then the voice coil motor (VCM) is stopped. Next, the spindle (DC) motor is stopped, so that the operation of the disk storage unit is stopped, and an error report (alarm occurrence) is made and the operator is informed of the error. 
     FIG. 13 is a perspective view of the magnetic recording head slider showing the fifth embodiment of the present invention. In this embodiment, there is provided MR element  15  exclusively used for detecting a contact, and this MR element  15  has the same structure as that of the magnetic transducer  47  composed of an MR element. That is, the magnetic transducer  47  is arranged at a position close to the outflow end of one rail  43 , and MR element  15  exclusively used for detecting a contact is arranged at a position close to the outflow end of the other rail  42 , so that the thermal asperity caused in the magnetic recording head slider in the contact with the magnetic disk can be detected. Due to the foregoing, the contact can be detected in this embodiment. 
     FIG. 14 is a perspective view of the magnetic recording head slider showing the sixth embodiment of the present invention. In this embodiment, there is provided a thermo-couple  16  in the magnetic recording head slider  20 , and a change in the temperature caused in the magnetic recording head slider  20  is detected by the thermo-couple  16  when the magnetic recording head slider  20  comes into contact with the magnetic disk. Due to the foregoing, the contact can be detected. In this connection, the land portion and the wiring portion can be composed in the same manner as that of the fifth and the sixth embodiments. 
     In the above explanations, referring to the accompanying drawings, several preferred embodiments to illustrate the present invention are described. However, it should be noted that the present invention is not limited to the above specific embodiments, ad variations may be made by one skilled in the art without departing from the spirit and scope of the invention. For example, although a magnetic disk storage unit is described in the above embodiment, it is possible to apply the present invention to a optical-magnetic disk storage unit or a optical-disk storage unit. 
     As explained above, according to the present invention, even if the size of a slider is reduced in accordance with the developments of a disk storage unit, the recording density of which is highly increased, when a resistance pattern or other minute elements are arranged in the suspension or the slider, it is surely possible to detect that the slider comes into contact with the recording medium.