Abstract:
A head slider for recording and playing back signals on a medium while floating on the medium has a head slider body and a lubrication layer on a slider surface of the head slider body. A lubricant of the lubrication layer has a main chain structure the same as a main chain structure of a lubricant of a lubrication layer of the medium. However, a terminal group of the lubricant of the lubrication layer, which is applied on the head slider has different structure from a structure of a terminal group of the lubricant of the lubrication layer on the medium. Thus, the adhesion does not occur between the lubrication layers of the head slider and the medium. As a result, the glide height of the head slider from the medium can be reduced by a distance of sub-nano-orders. The floating height of the head slider from the medium is decreased so that a plurality of signals are recorded on the medium in a high density.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to a head slider, and more particularly, to a head slider, which floats above a rotating medium.  
           [0003]    In an information memory storage device that has a medium rotatable at a high speed, a carriage having a head slider at an end thereof and a magnetic circuit rotating the carriage in opposite directions, it is required to further increase a density of record on the medium. In order to increase the record density of the medium, it is necessary to decrease a glide height of the head slider.  
           [0004]    2. Description of the Related Art  
           [0005]    A conventional head slider  10  is shown in FIG. 1. FIG. 1 shows a status that the conventional head slider is under writing or reading a record. A hard disk  20  rotates at a high speed and the head slider  10  floats above the hard disk  20  with a distance a due to air flow  25  induced by a high speed rotation of the hard disk  20 . In addition, in a stop mode, the head slider  10  touches the surface of the hard disk  20 .  
           [0006]    The hard disk  20  comprises a magnetic layer  22  on the surface of the substrate  21  and a lubrication layer  23  having a thickness of several nanometers on the surface thereof. The lubrication layer  23  is formed so as to decrease a friction with the head slider  10  at the time of starting rotation of the hard disk  20 , and to improve the durability of the hard disk  20 .  
           [0007]    The lubrication layer  23  is formed by applying a lubricant, and thereafter being processed by UV irradiation. A main chain of the lubricant is —(CF2—CF20)n-(CF2-0)m-, and a terminal group of the lubricant is Fomblin Zdol(Ausimont) family.  
           [0008]    The head slider  10  comprises a head slider body  11  made from ceramics and a magnetic head part  12  formed in the posterior-extremity surface  11   a  of the head slider body  11 . A slider surface  13 , which faces the hard disk  20 , corresponds to a surface  11   b  on which the ceramics of the head slider body  11  is exposed.  
           [0009]    In the combination of the above-mentioned head slider  10  and the hard disk  20 , the floating distance a is about 5 nanometers. The floating distance a is a height of the head slider  10  from the hard disk  20 . 5 nanometers is the lowest limit and it is difficult to make the floating distance smaller than 5 nanometers.  
           [0010]    A cause of difficulty in reducing the floating distance is considered to be an adhesion between the slider surface  13  of the head slider  10  and the lubrication layer  23  of the hard disk  20  due to the lubricant of the lubrication layer  23  of the hard disk  20  being transferred to the slider surface  13  of the head slider  10 .  
           [0011]    As a method for preventing a transfer of the lubricant of the lubrication layer  23  of the hard disk  20  to the slider surface  13  of the head slider  10 , JP,6-64869, A discloses a composition of an organic silicone functional group layer which is chemically bonded to a surface of the head slider.  
           [0012]    However, since the organic silicone functional group layer has characteristics of generating gas, the generated silicone gas enters between a hard disk and a head slider, which may result in occurrence of a risk of head crash.  
         SUMMARY OF THE INVENTION  
         [0013]    It is a general object of the present invention to provide a head slider and an information memory storage device which solve the above-mentioned problems.  
           [0014]    A more specific object of the present invention is to reduce the glide height of the head slider to the hard disk by a distance of sub-nano-orders without adhesion of lubricant layers of the head disk and the medium to each other.  
           [0015]    In order to achieve the above-mentioned object, there is provided according to one aspect of the present invention a head slider for recording and playing back signals on a medium while floating on the medium, comprising:  
           [0016]    a head slider body; and  
           [0017]    a lubrication layer on a slider surface of the head slider body,  
           [0018]    wherein a lubricant of the lubrication layer has a main chain structure the same as a main chain structure of a lubricant of a lubrication layer of the medium; and  
           [0019]    a terminal group has a structure different from a structure of a terminal group of the lubricant of the lubrication layer of the medium.  
           [0020]    Additionally, in the head slider according to the present invention, the main chain of the lubricant of the lubrication layer of the head slider body may be —(CF2—CF20)n-(CF2-0)m-;  
           [0021]    the terminal group of the lubricant of the lubrication layer of the head slider body may be selected from a group consisting of Fomblin Zdol family, Fomblin AM 3001(Ausimont) family, Amine family, MORESCO PHOSFANOL(matsumura Oil Research Cort.) family, and Fomblin Tetraol(Ausimont) family; and  
           [0022]    the terminal group of the head slider body may be different from the terminal group of the lubricant of the lubricant layer of the medium.  
           [0023]    In order to achieve the above-mentioned object, there is also provided according to another aspect of the present invention, an information memory storage device comprising, within a housing having a base, a rotatable medium, a carriage having a head slider at an end thereof, and a magnetic circuit which rotates the carriage in opposite directions, wherein the medium including:  
           [0024]    a substrate;  
           [0025]    a magnetic layer on the substrate; and  
           [0026]    a lubrication layer on a surface of the medium,  
           [0027]    wherein the head slider has a head slider body; and  
           [0028]    a lubrication layer on a slider surface of the head slider body,  
           [0029]    wherein a lubricant of the lubrication layer has a main chain structure the same as the main chain structure of the lubricant of the lubrication layer of the medium and  
           [0030]    a terminal group having a structure different from the structure of the terminal group of the lubricant of the lubrication layer of the medium.  
           [0031]    Additionally, in the information memory storage device according to the present invention, a main chain of the lubricant of the lubrication layer of the medium may be —(CF2—CF20)n-(CF2-0)m-; and  
           [0032]    a terminal group may be selected from a group consisting of Fomblin Zdol family, Fomblin AM 3001 family, Amine family, MORESCO PHOSFANOL family, and Fomblin Tetraol family;  
           [0033]    wherein a main chain of the lubricant of the lubrication layer of the head slider may be —(CF2—CF20)n-(CF2-0)m-;  
           [0034]    a terminal group is selected from a group consisting of Fomblin Zdol family, Fomblin AM 3001 family, Amine family, MORESCO PHOSFANOL family, and Fomblin Tetraol family; and  
           [0035]    the terminal group structure is different from the terminal group of the lubricant of the lubrication layer of the medium.  
           [0036]    Additionally, in the information memory storage device according to the present invention, the lubricant of the lubrication layer of the medium has a structure in which X1P(Dow Chemical Company) may be added to Fomblin Zdol family; and  
           [0037]    the terminal group of the lubricant of the lubrication layer of the head slider is selected from a group consisting of Fomblin AM 3001 family, Amine family, MORESCO PHOSFANOL family, and Fomblin Tetraol family.  
           [0038]    Additionally, in the information memory storage device according to the present invention, the terminal structure of the lubricant of the lubrication layer of the head slider may be Fomblin AM 3001 family.  
           [0039]    According to the present invention, the structure of the terminal group of the lubricant of the lubrication layer of the head slider is different from the structure of the terminal group of the lubricant of the medium. Thus, the adhesion does not occur between the lubrication layer of the head slider and the lubrication layer of the medium. As a result, the glide height of the head slider to the medium is reduced by a distance of sub-nano-orders as compared with a case in which no lubrication layer is provided on the head slider and another case in which the same terminal group is provided to the lubrication layer of the hard disk. Thus, the floating height of the head slider to the medium can be decreased. Then, signals can be recorded on the medium in a high density.  
           [0040]    In addition, the lubricant of the lubrication layer of the head slider and the lubricant of the lubrication layer of the medium have no characteristics of generating gas. So, the increase of the occurrence of a risk of head crash can be prevented even though the floating height of the head slider to the medium become small.  
           [0041]    Further, the structure of the terminal group of the lubricant of the lubrication layer on the medium has a structure in which X1P is added to Fomblin Zdol family, whereas the terminal group of the lubricant of the lubrication layer on the head slider is Fomblin AM 3001 family. Thus, the floating height of the head slider to the medium can be decreased, and signals can be recorded on the medium in a high density. 
       
    
    
       [0042]    Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.  
       BRIEF DESCRIPTION OF THE DRAWINGS  
       [0043]    [0043]FIG. 1 is a side view of a conventional head slider floating above a hard disk;  
         [0044]    [0044]FIG. 2 is a plan view of a hard disk device of a first embodiment of the present invention wherein a cover is removed;  
         [0045]    [0045]FIG. 3 is an expanded view showing a head slider combined with a hard disk shown in FIG. 2;  
         [0046]    [0046]FIG. 4A is a perspective view showing an experimental equipment for measuring a glide height;  
         [0047]    FIGS.  4 B- 4 J are side views of hard disks for glide height measurement;  
         [0048]    FIGS.  4 K- 4 P are side views of head sliders for glide height measurement;  
         [0049]    [0049]FIG. 5 is an illustration showing chemical structures of a terminal group of a lubricant.  
         [0050]    [0050]FIG. 6 is a graph showing a change in a glide height of first and second head sliders with respect to a first hard disk;  
         [0051]    [0051]FIG. 7 is a side view of a part of a hard disk device according to a second embodiment of the present invention;  
         [0052]    [0052]FIG. 8 is a side view of a part of a hard disk device according to a third embodiment of the present invention;  
         [0053]    [0053]FIG. 9 is a graph showing a change in a glide height of first and third head sliders with respect to the first hard disk;  
         [0054]    [0054]FIG. 10 is a side view of a part of a hard disk device according to a fourth embodiment of the present invention;  
         [0055]    [0055]FIG. 11 is a graph showing a change in a glide height of first and fifth head sliders with respect to the first hard disk;  
         [0056]    [0056]FIG. 12 is a side view of a part of a hard disk device according to a fifth embodiment of the present invention;  
         [0057]    [0057]FIG. 13 is a graph showing a change in a glide height of first and second head sliders with respect to a third hard disk;  
         [0058]    [0058]FIG. 14 is a side view of a part of a hard disk device according to a sixth embodiment of the present invention;  
         [0059]    [0059]FIG. 15 is a graph showing a change in a glide height of second and fifth head sliders with respect to the third hard disk;  
         [0060]    [0060]FIG. 16 is a side view of a part of a hard disk device according to a seventh embodiment of the present invention;  
         [0061]    [0061]FIG. 17 is a graph showing a change in a glide height of first and third head sliders with respect to a fourth hard disk; and  
         [0062]    [0062]FIG. 18 is a table showing numerical data of the graph of FIGS. 6, 9,  11 ,  13 ,  15 , and  17 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     FIRST EMBODIMENT  
       [0063]    [0063]FIG. 2 shows a hard disk device  30  according to a first embodiment of the present invention. The hard disk device  30  comprises a box-shaped housing  32  having a base  31  and a cover (not shown) which covers an upper surface of the housing  32 . The housing  32  includes a hard disk  40  which rotates counterclockwise at a high speed as indicated by arrow CC in FIG. 2, a carriage  70  which has a head slider  50  at an end thereof, and a If magnetic circuit  80  which rotates the carriage  70  in opposite directions by an electromagnetic force. In FIG. 3, while the head slider  50  is writing or reading-out a record, the hard disk  40  rotates at a high speed and the head slider  50  floats above the hard disk  40  with a distance or height b due to an air flow  45  induced by a high speed rotation of the hard disk  40 .  
         [0064]    As shown in FIG. 3, the hard disk  40  comprises a magnetic layer  42  on the surface of the substrate  41  and a lubrication layer  43  whose thickness is several nanometers on the surface thereof. In order to decrease the height of the head slider  50  floating above the hard disk  40 , a texture treatment is not applied to the substrate  41  so as to make the surface of the hard disk  40  flat and smooth. The lubrication layer  43  is formed by applying a lubricant, and thereafter being processed by UV irradiation.  
         [0065]    As shown in FIG. 3, the head slider  50  comprises a head slider body  51  made from ceramics, a magnetic head part  52  formed in the posterior-extremity surface  51   a  of the head slider body  51 , and a lubrication layer  53  on a surface of  51   b,  which faces the hard disk  40 . The head slider  50  has a slider surface  54 , which faces the hard disk  40 . The lubrication layer  53  is formed by applying a lubricant, and thereafter being processed by UV irradiation.  
         [0066]    The slider surface  54  has a floating surface  55  at a front part of the head slider  50 . The slider surface  54  also has a couple of floating surfaces  56  and  57  at the rear end of the head slider  50 . Moreover, the slider surface  54  has a convexo part  58  in a central part of the head slider  50 . While the hard disk  40  rotates at a high speed, a floating force is generated in the head slider  50  by the floating surface  55  at the front part of the head slider  50  and the floating surfaces  56  and  57  at the rear end of the head slider  50 . Thus, a negative pressure area is formed in the convexo part  58  in a central part of the head slider  50 . The head slider  50  floats in a stable condition.  
         [0067]    A convex part  59 , which is made of diamond like carbon, is formed on the floating surfaces  55  and  56 . During a stop mode of the hard disk  40 , the convex part  59  touches the surface of the hard disk  40 , and, thus, the floating surfaces  55 ,  56  and  57  are lifted from the surface of the hard disk  40 . Accordingly even though the surface of the hard disk  40  is flat and smooth, the head slider  50  is prevented from adhering the surface of the hard disk  40 .  
         [0068]    Hereinafter, a structure of the lubricant of the lubrication layer  43  of the hard disk  40  and a structure of the lubricant of the lubrication layer  54  of the head slider  50  will be explained.  
         [0069]    A main chain of the lubricant of the lubrication layer  43  of the hard disk  40  is —(CF2—CF20)n-(CF2-0)m-, and a terminal group of the lubricant of the lubrication layer  43  of the hard disk  40  is Fomblin Zdol family(Fomblin Zdol 2000).  
         [0070]    Fomblin Zdol family is expressed as a chemical formula showing in FIG. 5-(A).  
         [0071]    A main chain of the lubricant of the lubrication layer  54  of the head slider  50  is —(CF2—CF20)n-(CF2-0)m-, and a terminal group of the lubricant of the lubrication layer  54  of the head slider  50  is Fomblin AM 3001 family.  
         [0072]    Fomblin AM 3001 is expressed as a chemical formula showing in FIG. 5-(B).  
         [0073]    Therefore, the main chain structure of the lubricant of the lubrication layer  43  of the hard disk  40  and the lubricant of the lubrication layer  54  of the head slider  50  have the same structure as —(CF2—CF20)n-(CF2-0)m-. However, the terminal group of the hard disk  40  is Fomblin Zdol family while the terminal group of the head slider  50  is Fomblin AM 3001 family.  
         [0074]    The minimum distance of a floating height b of the head slider  50  relative to the surface of the hard disk  40  is smaller than a conventional one by about 0.75 to 1 nanometers. This will be understood from the results of the experiments described below.  
         [0075]    The reason for this is considered as follows.  
         [0076]    A transfer of the lubricant of the lubrication layer  43  of the hard disk  40  to the head slider  50  is not observed. It is considered that no adhesion force is generated between the lubrication layer  54  of the head slider  50  and the lubrication layer  43  of the hard disk  40 , which were close to each other.  
         [0077]    In addition, since both the lubrication layer  43  of the hard disk  40  and the lubrication layer  54  of the head slider  50  have no characteristics of generating gas, there is no risk of occurrence of a head crash.  
         [0078]    Hereinafter, experiments used as the above-mentioned basis and results of the experiments will be explained.  
         [0079]    [0079]FIG. 4A is a perspective view showing the experimental equipment  90 , which measures the glide height. The glide height is a distance or height from a centrer line of average roughness Ra of a surface of a hard disk to a head slider. The experimental equipment  90  comprises an arm  91 , an AE(Acoustic Emission) sensor  92  having a piezo element, a motor  94  that rotates a standard hard disk for the glide height measurement and a hard disk equipped in a hard disk device, and a movement stand  95  that moves in a direction of radius of the hard disk. The arm  91  has a slider part for measurement of the glide height  91   b  at an end of a gimbal part  91   a.  A main part side of the arm  91  is mounted on the movement stand  95 . The AE sensor  92  is mounted on the main part of the arm  91 . The AE sensor  92  detects ultrasonic waves, which are generated by an impact caused by the slider for glide height measurement contacting the hard disk for glide height measurement or a normal hard disk and transfer through the arm  91 .  
         [0080]    As the hard disks for the experiment, the standard hard disks for the glide height measurement and the normal hard disks were prepared, as shown in FIGS. 4B to  4 J.  
         [0081]    Each of the standards hard disks for the glide height measurement has many bumps on an upper surface thereof. A plurality of standard hard disks, which have bumps with different heights, were prepared. For example, a standard hard disk  100  has bumps  100   a  with 3 nm height as shown in FIG. 4B, a standard hard disk  101  has bumps  101   a  with 5 nm height as shown in FIG. 4C, and a standard hard disk  102  has bumps  102   a  with 7 nm height as shown in FIG. 4D.  
         [0082]    The standard hard disks  100 - 102  for the glide height measurement were prepared for investigating a relationship between a glide height and a number of rotations of a hard disk.  
         [0083]    The normal hard disks were hard disks, which are incorporated in a hard disk device. 5 pieces of normal hard disks with different types of lubricants of a lubrication layer were prepared. The average roughness Ra in a central line of a surface of each of the hard disks was 0.4 nm.  
         [0084]    A structure of the main chain of each lubricant was —(CF2—CF20)n-(CF2-0)m-. The structures of the main chains were the same, but the terminal groups were different.  
         [0085]    A first hard disk  110  shown in FIG. 4E had a lubrication layer  110   a.  A structure of a main chain of a lubricant of the lubrication layer  110   a  was —(CF2—CF20)n-(CF2-0)m-, and a structure of a terminal group of the lubricant of the lubrication layer  110   a  was Fomblin Zdol family.  
         [0086]    A second hard disk  111  shown in FIG. 4F had a lubrication layer  111   a.  A structure of a main chain of a lubricant of the lubrication layer  111   a  was —(CF2—CF20)n-(CF2-0)m-, and a structure of a terminal group of the lubricant of a lubrication layer  111   a  was Fomblin Zdol family with X1P family.  
         [0087]    X1P family is expressed as a chemical formula showing in FIG. 5-(F).  
         [0088]    A third hard disk  112  shown in FIG. 4G had a lubrication layer  112   a.  A structure of a main chain of a lubricant of the lubrication layer  112   a  was —(CF2—CF20)n-(CF2-0)m-, and a structure of a terminal group of the lubricant of the lubrication layer  112   a  was Fomblin AM 3001 family.  
         [0089]    A fourth hard disk  113  shown in FIG. 4H had a lubrication layer  113   a.  A structure of a main chain of a lubricant of the lubrication layer  113   a  was —(CF2—CF20)n-(CF2-0)m-, and a structure of a terminal group of the lubricant of the lubrication layer  113   a  was Amine family.  
         [0090]    Amine family is expressed as a chemical formula showing in FIG. 5-(C).  
         [0091]    A fifth hard disk  114  shown in FIG. 4I had a lubrication layer  114   a.  A structure of a main chain of a lubricant of the lubrication layer  114   a  was —(CF2—CF20)n-(CF2-0)m-, and a structure of a terminal group of the lubricant of the lubrication layer  114   a  was MORESCO PHOSFANOL family.  
         [0092]    MORESCO PHOSFANOL family is expressed as a chemical formula showing in FIG. 5-(D).  
         [0093]    A sixth hard disk  115  shown in FIG. 4J had a lubrication layer  115   a.  A structure of a main chain of a lubricant of the lubrication layer  115   a  was —(CF2—CF20)n-(CF2-0)m-, and a structure of a terminal group of the lubricant of the lubrication layer  115   a  was Fomblin Tetraol family.  
         [0094]    Fomblin Tetraol family is expressed as a chemical formula showing in FIG. 5-(E).  
         [0095]    Six types of the head sliders for the glide height measurement shown in FIGS.  4 K- 4 P were prepared.  
         [0096]    A slider surface of each of the head sliders for the glide height measurement had rails on both sides thereof.  
         [0097]    A first head slider  120  shown in FIG. 4K had a lubrication layer  120   a.  A structure of a main chain of a lubricant of the lubrication layer  120   a  was —(CF2—CF20)n-(CF2-0)m-, and a structure of a terminal group of the lubricant of the lubrication layer  120   a  was Fomblin Zdol family.  
         [0098]    A second head slider  121  shown in FIG. 4L had a lubrication layer  121   a.  A structure of a main chain of a lubricant of the lubrication layer  121   a  was —(CF2—CF20)n-(CF2-0)m-, and a structure of a terminal group of the lubricant of the lubrication layer  121   a  was Fomblin AM 3001 family.  
         [0099]    A third head slider  122  shown in FIG. 4M had a lubrication layer  122   a.  A structure of a main chain of a lubricant of the lubrication layer  122   a  was —(CF2—CF20)n-(CF2-0)m-, and a structure of a terminal group of the lubricant of the lubrication layer  122   a  was Amine family.  
         [0100]    A fourth head slider  123  shown in FIG. 4N had a lubrication layer  123   a.  A structure of a main chain of a lubricant of the lubrication layer  123   a  was —(CF2—CF20)n-(CF2-0)m-, and a structure of a terminal group of the lubricant of the lubrication layer  123   a  was MORESCO PHOSFANOL family.  
         [0101]    A fifth head slider  124  shown in FIG. 40 had a lubrication layer  124   a.  A structure of a main chain of a lubricant of the lubrication layer  124   a  was —(CF2—CF20)n-(CF2-0)m-, and a structure of a terminal group of the lubricant of the lubrication layer  124   a  was Fomblin Tetraol family.  
         [0102]    A sixth head slider  125  shown in FIG. 4P did not have a lubrication layer.  
         [0103]    The experiments were performed as follows. The first step was (1) to investigate a relationship between a glide height and a number of rotations of the hard disk. Then, the next step was (2) to find a glide height.  
         [0104]    (1) Steps to investigate a relationship between a glide height and a number of rotations of the hard disk:  
         [0105]    The sixth head slider  125  was fixed to a gimbal part of the arm  91 . The standard hard disk  100  was fixed to the motor  94 , and rotated at a high speed. The number of rotations of the standard hard disk  100  was gradually decreased, and the number of rotations of the standard hard disk  100  was recorded when the head slider  124  touched the bump  110   a  and the AE sensor  92  outputted a signal. By moving the movement stand  95 , the head slider  124  was moved to a different radial position on the standard hard disk  100  so as to perform the above-mentioned operation. Thereby, the rotating speed was detected, when the glide height was 3 nm, at several positions of the radius.  
         [0106]    The standard hard disk  100  was removed, then the above-mentioned operation was performed with the standard hard disk  101 . Thereby, the rotating speed when the glide height was  5 nm was detected at several positions of the radius.  
         [0107]    The standard hard disk  101  was removed, then the above-mentioned operation was performed with the standard hard disk  102 . Thereby, the rotating speed when the glide height was  7 nm was detected at several positions of the radius.  
         [0108]    A table, which shows a relationship between a glide height and a speed of the hard disk, was obtained by the above-mentioned operations.  
         [0109]    (2) Steps to find a glide height:  
         [0110]    The standard hard disk  101  was removed, then the first hard disk  110  shown in FIG. 4E was attached to the experimental device. Instead of the sixth head slider  125 , the first head slider  120  shown in FIG. 4K was fixed to the gimbal part of the arm  91 .  
         [0111]    The main chain of the lubrication layer  110   a  of the first hard disk  110  had the same structure as the main chain of the lubrication layer  120   a  of the first head slider  120  in the form of —(CF2—CF20)n-(CF2-0)m-. In addition, the terminal group of the lubrication layer  110   a  of the first hard disk  110  had the same structure as the terminal group of the lubrication layer  120   a  of the first head slider  120  in the form of Fomblin Zdol family.  
         [0112]    The first hard disk  110  was rotated at a high speed. Then, the number of rotations of the first hard disk  110  was gradually decreased. Also, the number of rotations of the first hard disk  110  was recorded when the first head slider  120  touched the surface of the first hard disk  110  and the AE sensor  92  outputted a signal. By moving the movement stand  95 , the head slider  120  was moved to a different radial position of the first hard disk  110  so as to be performed the above-mentioned recording step. Thus, a glide height can be detected by applying the number of rotations of the first hard disk  110  when AE sensor outputted a signal to the above-mentioned table. A line IA in FIG. 6 shows the obtained glide height. When the glide height was obtained at a radial position of 22 mm, the glide height was 5.49 nm.  
         [0113]    Then, instead of the first head slider  120 , the second head slider  121  shown in FIG. 4L was mounted to the gimbal part of the arm  91  in the experimental equipment.  
         [0114]    By replacing the head slider, the terminal group of the lubrication layer  110   a  of the first hard disk  110  and the terminal group of the lubrication layer  121   a  of the first head slider  121  were in the different forms of Fomblin Zdol family and Fomblin AM 3001 family, respectively. However, both the main chain of the lubrication layer  110   a  of the first hard disk  110  and the lubrication layer  121   a  of the first head slider  121  had the same structure as —(CF2—CF20)n-(CF2-0)m-.  
         [0115]    In this state, similar to the above-mentioned steps, the first hard disk  110  was rotated at a high speed. Then, the number of rotations of the first hard disk  110  was gradually decreased. Also, the number of rotations of the first hard disk  110  was recorded when the second head slider  121  touched the surface of the first hard disk  110  and the AE sensor  92  outputted a signal. By moving the movement stand  95 , the second head slider  121  was moved to a different radial position of the first hard disk  110  so as to perform the above-mentioned recording steps. Thus, the glide height was detected by applying the number of rotations of the first hard disk  110  when the AE sensor outputted a signal to the above-mentioned table. A line I in FIG. 6 shows obtained glide height. When the glide height was obtained at a radial position of 22 mm, the number of rotations of the first hard disk  110  was decreased and became around 1500 rpm. Then, the AE sensor outputted a signal due to a contact of the second head slider  121  to the surface of the first hard disk  110 . The glide height was 4.74 nm and lower than 0.77 nm compared to the example of the first head slider  120 .  
         [0116]    Comparing the line I in FIG. 6 with the line IA in FIG. 6, the glide height was reduced by 0.75 to 1.27 nm due to the change from a state in which the terminal groups of the lubricants of the lubrication layers, which faces each other, have the same structure of Fomblin Zdol family to a state in which the terminal groups have different structures of Fomblin Zdol family and Fomblin AM 3001 family.  
       SECOND EMBODIMENT  
       [0117]    [0117]FIG. 7 is a side view of a part of a hard disk device  30 - 1  according to a second embodiment of the present invention.  
         [0118]    Comparing with the hard disk device  30  shown in FIG. 3, the hard disk device  30 - 1  has the same head slider as the head slider  50  shown in FIG. 3, and a hard disk  40 - 1  has a different structure compared to the hard disk  40  shown in FIG. 3.  
         [0119]    The difference between the hard disk  40 - 1  and the above-mentioned hard disk  40  is in a lubrication layer  43 - 1 . A structure of the main chain of the lubricant of the lubrication layer  43 - 1  is —(CF2—CF20)n-(CF2-0)m-, and a structure of the terminal group of the lubricant of the lubrication layer  43 - 1  is Fomblin Zdol family with X1P family.  
         [0120]    Therefore, the structure of the main chain of the lubricant of the lubrication layer  43 - 1  of the hard disk  40 - 1  and the lubricant of the lubrication layer  53  of the head slider  50  are in the same form of —(CF2—CF20)n-(CF2-0)m-. However, the terminal group of the lubricant of the lubrication layer  43 - 1  of the hard disk  40 - 1  is Fomblin Zdol family+X1P family, and the terminal group of the lubricant of the lubrication layer  53  art of the head slider  50  is Fomblin AM 3001 family.  
         [0121]    The minimum floating height c of the head slider  50  from a surface of the hard disk  40  is reduced by more than 1 nm as compared to the conventional one. This will be understood from the results of the experiments described below.  
         [0122]    The second hard disk  111  shown in FIG. 4F and the second head slider  121  shown in FIG. 4L were mounted to the experimental equipment in FIG. 4A. Then the experiment was performed with above-mentioned equipment. The second hard disk  111  was rotated at a high speed. The second head slider  121  was positioned at 22 mm of radius of the second hard disk  111 . Then, the number of rotations of the second hard disk  111  was decreased gradually. Even though the number of rotations of the second hard disk  111  dropped and became 1000 rpm, no signal was outputted from the AE sensor  92 . The glide height was too low to be detected by the above-mentioned experimental equipment.  
       THIRD EMBODIMENT  
       [0123]    [0123]FIG. 8 is a side view of a part of the hard disk device  30 - 2  according to a third embodiment of the present invention.  
         [0124]    Comparing with the hard disk device  30  shown in FIG. 3, the hard disk device  30 - 2  has the same hard disk as the hard disk  40  shown in FIG. 3, and a head slider  50 - 1  has a different structure compared to the head slider  50  shown in FIG. 3.  
         [0125]    The difference between the head slider  501  and the above-mentioned head slider  50  is in a lubrication layer  53 - 1 . A structure of the main chain of the lubricant of the lubrication layer  53 - 1  is —(CF2—CF20)n-(CF2-0)m-, and a structure of the terminal group of the lubricant of the lubrication layer  53 - 1  is Amine family.  
         [0126]    Therefore, the structure of the main chain of the lubricant of the lubrication layer  43  of the hard disk  40  and the lubricant of the lubrication layer  53 - 1  of the head slider  50 - 1  are in the same form of —(CF2—CF20)n-(CF2-0)m-. However, the terminal group of the lubricant of the lubrication layer  43  of the hard disk  40  is Fomblin Zdol family, and the terminal group of the lubricant of the lubrication layer  53 - 1  of the head slider  50 - 1  is Amine family.  
         [0127]    The minimum floating height d of the head slider  50 - 1  from a surface of the hard disk  40  is reduced by 0.15 to 0.59 nm as compared to the conventional one. This will be understood from the results of the experiments described below.  
         [0128]    The first hard disk  110  shown in FIG. 4E and the first head slider  120  shown in FIG. 4K were mounted to the experimental equipment in FIG. 4A. Then the glide height was obtained with above-mentioned equipment using the same operations as before. In this case, a structure of the main chain of the lubricant of the first hard disk  110  and the lubricant of the first head slider  120  were the same structure. In addition, both the terminal group of the first hard disk  110  and the first head slider  120  had the same structure in the form of Fomblin Zdol 2000. A line IIA in FIG. 9 shows the obtained glide height.  
         [0129]    Then, instead of the first head slider  120 , the third head slider  122  shown in FIG. 4M was mounted to the experimental equipment. Thus, the glide height was obtained with same operations as above-mentioned. By replacing the head slider, the terminal group of the lubricant of the first hard disk  110  and the terminal group of the lubricant of the third head slider  122  were in the different forms of Fomblin Zdol 2000 and Amine family, respectively. A line II in FIG. 9 shows the obtained glide height.  
         [0130]    Comparing the line II in FIG. 9 with the line IIA in FIG. 9, the glide height was reduced by 0.15 to 0.59 nm due to the change from a state in which the terminal groups of the lubricants of the lubrication layers, which faces each other, have the same structure of Fomblin Zdol family to a state in which the terminal groups have different structures of Fomblin Zdol family and Fomblin AM 3001 family.  
       FOURTH EMBODIMENT  
       [0131]    [0131]FIG. 10 is a side view of a part of hard disk device  30 - 3  according to a fourth embodiment of the present invention.  
         [0132]    Comparing with the hard disk device  30  shown in FIG. 3, the hard disk device  30 - 3  has the same hard disk as the hard disk  40  shown in FIG. 3, and a head slider  50 - 2  has a different structure as compared to the head slider  50  shown in FIG. 3.  
         [0133]    The difference between the head slider  502  and the above-mentioned head slider  50  is in a lubrication layer  53 - 2 . A structure of the main chain of the lubricant of the lubrication layer  53 - 2  is —(CF2—CF20)n-(CF2-0)m-, and a structure of the terminal group of the lubricant of the lubrication layer  53 - 2  is Fomblin Tetraol family.  
         [0134]    Therefore, the structure of the main chain of the lubricant of the lubrication layer  43  of the hard disk  40  and the lubricant of the lubrication layer  53 - 2  of the head slider  50 - 2  are in the same form of —(CF2—CF20)n-(CF2-0)m-. However, the terminal group of the lubricant of the lubrication layer  43  of the hard disk  40  is Fomblin Zdol 2000, and the terminal group of the lubricant of the lubrication layer  53 - 2  of the head slider  50 - 2  is Fomblin Tetraol family.  
         [0135]    The minimum distance of the floating height e of the head slider  50 - 2  from a surface of the hard disk  40  is reduced by 0.29 to 0.75 nm as compared to the conventional one. This will be understood from the results of the experiments described below.  
         [0136]    The first hard disk  110  shown in FIG. 4E and the first head slider  120  shown in FIG. 4K were mounted to the experimental equipment in FIG. 4A. Then the glide height was obtained with the above-mentioned equipment using the same operations as before. In this case, a structure of the main chain of the lubricant of the first hard disk  110  and the lubricant of the first head slider  120  were the same structure. In addition, both the terminal group of the first hard disk  110  and the first head slider  120  had the same structure in the form of Fomblin Zdol 2000. A line IIIA in FIG. 11 shows the obtained glide height.  
         [0137]    Then, instead of the first head slider  120 , the fifth head slider  124  in FIG. 40 was mounted to the experimental equipment. Thus, the glide height was obtained with same operations as above-mentioned. By replacing the head slider, the terminal group of the lubricant of the first hard disk  110  and the terminal group of the lubricant of the fifth head slider  124  were in the different forms of Fomblin Zdol 2000 and Fomblin Tetraol, respectively. A line III in FIG. 11 shows the obtained glide height.  
         [0138]    Comparing the line III in FIG. 11 with the line IIIA in FIG. 11, the glide height was reduced by 0.29 to 0.75 nm due to the change from a state in which the terminal groups of the lubricants of the lubrication layers, which faces each other, have the same structure of Fomblin Zdol family to a state in which the terminal groups have different structures of Fomblin Zdol family and Fomblin Tetraol.  
       FIFTH EMBODIMENT  
       [0139]    [0139]FIG. 12 is a side view of a part of a hard disk device  30 - 4  according to a fifth embodiment of the present invention.  
         [0140]    Comparing with the hard disk device  30  shown in FIG. 3, the hard disk device  30 - 4  has a different head slider  50 - 3  and a different hard disk  40 - 2  from the above-mentioned head slider  50  and the hard disk  40 .  
         [0141]    The difference between the head slider  50 - 3  and the above-mentioned head slider  50  is in a lubrication layer  53 - 3 . A structure of the main chain of the lubricant of the lubrication layer  53 - 3  is —(CF2—CF20)n-(CF2-0)m-, and a structure of the terminal group of the lubricant of the lubrication layer  53 - 3  is Fomblin Zdol 2000.  
         [0142]    The difference between the hard disk  40 - 2  and the above-mentioned hard disk  40  is in a lubrication layer  43 - 2 . A structure of the main chain of the lubricant of the lubrication layer  43 - 2  is —(CF2—CF20)n-(CF2-0)m-, and a structure of the terminal group of the lubricant of the lubrication layer  43 - 2  is Fomblin AM 3001.  
         [0143]    Therefore, the structure of the main chain of the lubricant of the lubrication layer  43 - 2  of the hard disk  40 - 2  and the lubricant of the lubrication layer  53 - 3  of the head slider  50 - 3  are in the same form of —(CF2—CF20)n-(CF2-0)m-. However, the terminal group of the lubricant of the lubrication layer  43 - 2  of the hard disk  40 - 2  is Fomblin AM 3001, and the terminal group of the lubricant of the lubrication layer  53 - 3  of the head slider  50 - 3  is Fomblin Zdol  2000 . Thus, the fifth embodiment has the opposite relationship with respect to the terminal groups of the hard disk and the head slider in the first embodiment as shown in FIG. 3.  
         [0144]    The minimum floating height f of the head slider  50 - 3  from a surface of the hard disk  40 - 2  is reduced by 0.15 to 0.59 nm as compared to the conventional one. This will be understood from the results of the experiments described below.  
         [0145]    The third hard disk  112  shown in FIG. 4G and the second head slider  121  shown in FIG. 4L were mounted to the experimental equipment in FIG. 4A. Then the glide height was obtained with above-mentioned equipment using the same operations as before. In this case, a structure of the main chain of the lubricant of the third hard disk  112  and the lubricant of the second head slider  121  were the same structure. In addition, both the terminal group of the third hard disk  112  and the second head slider  121  had the same structure in the form of Fomblin AM 3001. A line IVA in FIG. 13 shows the obtained glide height.  
         [0146]    Then, instead of the second head slider  121 , the first head slider  120  shown in FIG. 4K was mounted to the experimental equipment. Thus, the glide height was obtained with same operations as above-mentioned. By replacing the head slider, the terminal group of the lubricant of the third hard disk  112  and the terminal group of the lubricant of the first head slider  120  were in the different forms of Fomblin AM 3001 and Fomblin Zdol 2000, respectively. The fifth embodiment has a relationship, which the terminal groups of the hard disk and the head slider are different structures. A line IV in FIG. 13 shows the obtained glide height.  
         [0147]    Comparing the line IV in FIG. 13 with the line IVA in FIG. 13, the glide height was reduced by 0.15 to 0.59 nm due to the change from a state in which the terminal groups of the lubricants of the lubrication layers, which faces each other, have the same structure of Fomblin AM 3001 family to a state in which the terminal groups have different structures of Fomblin AM 3001 family and Fomblin Zdol family.  
       SIXTH EMBODIMENT  
       [0148]    [0148]FIG. 14 is a side view of a part of a hard disk device  30 - 5  according to a sixth embodiment of the present invention.  
         [0149]    Comparing with the hard disk device  30  shown in FIG. 3, the hard disk device  30 - 5  has the different head slider  50 - 2  and the different hard disk  40 - 2  from the above-mentioned head slider  50  and the hard disk  40 .  
         [0150]    The difference between the head slider  502  and the above-mentioned head slider  50  is in a lubrication layer  53 - 2 . A structure of the main chain of the lubricant of the lubrication layer  53 - 2  is —(CF2—CF20)n-(CF2-0)m-, and the structure of the terminal group of the lubricant of a lubrication layer  53 - 2  is Fomblin Tetraol.  
         [0151]    The difference between the hard disk  40 - 2  and the above-mentioned hard disk  40  is in a lubrication layer  43 - 2 . A structure of the main chain of the lubricant of the lubrication layer  43 - 2  is —(CF2—CF20)n-(CF2-0)m-, and the structure of the terminal group of the lubricant of the lubrication layer  43 - 2  is Fomblin AM 3001.  
         [0152]    Therefore, the structure of the main chain of the lubricant of the lubrication layer  43 - 2  of the hard disk  40 - 2  and the lubricant of the lubrication layer  53 - 2  of the head slider  50 - 2  are in the same form of —(CF2—CF20)n-(CF2-0)m-. However, the terminal group of the lubricant of the lubrication layer  43 - 2  of the hard disk  40 - 2  is Fomblin AM 3001, and the terminal group of the lubricant of the lubrication layer  53 - 2  of the head slider  50 - 2  is Fomblin Tetraol.  
         [0153]    The minimum floating height g of the head slider  50 - 2  from a surface of the hard disk  40 - 2  is reduced by 0.25 to 0.60 nm as compared to the conventional one. This will be understood from the results of the experiments described below.  
         [0154]    The third hard disk  112  shown in FIG. 4G and the second head slider  121  shown in FIG. 4L were mounted to the experimental equipment in FIG. 4A. Then the glide height was obtained with above-mentioned equipment using the same operations as before. The structure of the main chain of the lubricants of the third hard disk  112  and the lubricants of the second head slider  121  were the same structure. In addition, both the terminal group of the third hard disk  112  and the second head slider  121  had the same structure in the form of Fomblin AM 3001. A line VA in FIG. 14 shows the obtained glide height.  
         [0155]    Then, instead of the second head slider  121 , the fifth head slider  124  shown in FIG. 40 was mounted to the experimental equipment. Thus, the glide height was obtained with same operations as above-mentioned. By replacing the head slider, the terminal group of the lubricant of the third hard disk  112  and the terminal group of the lubricant of the fifth head slider  124  were in the different forms of Fomblin AM 3001 and Fomblin Tetraol, respectively. The sixth embodiment has a relationship, which the terminal groups of the hard disk and the head slider are different structures. A line V in FIG. 14 shows the obtained glide height.  
         [0156]    Comparing the line V in FIG. 14 with the line VA in FIG. 14, the glide height was reduced by 0.25 to 0.60 nm due to the change from a state in which the terminal groups of the lubricants of the lubrication layers, which faces each other, have the same structure of Fomblin AM 3001 family to a state in which the terminal groups have different structures of Fomblin AM 3001 family and Fomblin Tetraol.  
       SEVENTH EMBODIMENT  
       [0157]    [0157]FIG. 16 is a side view of a part of a hard disk device  30 - 6  according to a seventh embodiment of the present invention.  
         [0158]    Comparing with the hard disk device  30  shown in FIG. 3, the hard disk device  30 - 6  has a structurally different hard disk  40 - 3  from the above-mentioned hard disk  40 .  
         [0159]    The difference between the hard disk  40 - 3  and the above-mentioned hard disk  40  is in a lubrication layer  43 - 3 . A structure of the main chain of the lubricant of the lubrication layer  43 - 3  is —(CF2—CF20)n-(CF2-0)m-, and a structure of the terminal group of the lubricant of the lubrication layer  43 - 3  is Amine family.  
         [0160]    Therefore, the structure of the main chain of the lubricant of the lubrication layer  43 - 3  of the hard disk  40 - 3  and the lubricant of the lubrication layer  53  of the head slider  50  are in the same form of —(CF2—CF20)n-(CF2-0)m-. However, the terminal group of the lubricant of the lubrication layer  43 - 3  of the hard disk  40 - 3  is Amine family, and the terminal group of the lubricant of the lubrication layer  53  of the head slider  50  is Fomblin Zdol 2000.  
         [0161]    The minimum floating height h of the head slider  50  from a surface of the hard disk  40 - 3  is reduced by 0.37 to 0.54 nm as compared to the conventional one. This will be understood from the results of the experiments described below.  
         [0162]    The fourth hard disk  113  shown in FIG. 4H and the third head slider  122  shown in FIG. 4M were mounted to the experimental equipment in FIG. 4A. Then the glide height was obtained with above-mentioned equipment using the same operations as before. The structure of the main chain of the lubricant of the fourth hard disk  113  and the lubricant of the third head slider  122  were the same structure. In addition, both the terminal group of the fourth hard disk  113  and the third head slider  122  had the same structure in the form of Amine family. A line VIA in FIG. 17 shows the obtained glide height.  
         [0163]    Then, instead of the third head slider  122 , the first head slider  120  shown in FIG. 4K was mounted to the experimental equipment. Thus, the glide height was obtained with same operations as above-mentioned. By replacing the head slider, the terminal group of the lubricant of the fourth hard disk  113  and the terminal group of the lubricant of the first head slider  120  are in the different forms of Amine family and Fomblin Zdol 2000, respectively. The seventh embodiment has a relationship, which the terminal groups of the hard disk and the head slider are different structures. A line VI in FIG. 17 shows the obtained glide height.  
         [0164]    Comparing the line VI in FIG. 17 with the line VIA in FIG. 17, the glide height was reduced by 0.37 to 0.54 nm due to the change from a state in which the terminal groups of the lubricants of the lubrication layers, which faces each other, have the same structure of Fomblin AM 3001 family to a state in which the terminal groups have different structures of Fomblin AM 3001 family and Fomblin Zdol 2000.  
         [0165]    [0165]FIG. 18 is a table showing the numerical data of the graph of the above-mentioned FIGS. 6, 9,  11 ,  13 ,  15 , and  17 .  
         [0166]    It is possible to decrease a glide height by means of not only the above-mentioned combination in the first to seventh embodiments but also any different combination of a lubricant of a head slider and a lubricant of a hard disk.  
         [0167]    The present invention is not limited to the specifically disclosed embodiments, and variations and modifications may be made without departing from the scope of the present invention.  
         [0168]    The present application is based on Japanese priority application No.2001-181916 filed on Jun. 15, 2001, the entire contents of which are hereby incorporated by reference.