Abstract:
A slider portion is provided with protrusion portions having a spherical surface, contacting a recording medium. A center of a magnetic pole is arranged on the line C 1  connecting the vertices of the protrusion portions. Line C 1  is more or less aligned with the gliding direction of the protrusion portions. Thereby, positional variations between the magnetic pole and the surface of the recording medium can be minimized even when the head slider is tilted with respect to the surface of the recording medium. Thus, a gliding converter support structure is provided whose conversion efficiency does not decrease when it is tilted with respect to the surface of the recording medium, which is easy to manufacture, has little gliding resistance, and does not easily accumulate dust.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates mainly to a converter support structure gliding in contact over a recording medium. More specifically, the present invention relates to a gliding converter support structure for a magnetic recording device or an optomagnetic recording and reproducing device used as an external storage device for a computer, or as a recording and reproducing device for music or video signals or other information. 
     2. Description of the Prior Art 
     A common example of a conventional gliding converter support structure is a magnetic core support structure for magnetic recording. Magnetic tape and flexible disks used to be the main media using such a structure, but recently minidisks (referred to as “MDs” in the following) are becoming increasingly popular as optomagnetic recording media for recording music. A prerequisite for MDs is the use of a gliding magnetic head slider for optomagnetic overwriting using a modulated magnetic field, and the disk has a gliding film for gliding. The following is a discussion of a magnetic head slider for MDs serving as a converter support structure. 
     A conventional gliding magnetic head slider for optomagnetic recording, particularly for MDs, is disclosed in Publication of Unexamined Japanese Patent Application No. Hei 6-195851. Its overall structure is shown in FIG.  4 ( a ). 
     In FIG.  4 ( a ), numeral  101  denotes a slider means serving as a converter support structure, on which a magnetic core  102  serving as a converter, and a coil (not shown in the drawings) are installed. Publication of Unexamined Japanese Patent Application No. Hei 7-129902 discloses details concerning the slider means  101 , which are illustrated in FIG.  4 ( b ). A cylindrical surface  101   a  is formed as a gliding surface on a surface of the slider means that opposes the disk. Numeral  102   a  denotes the magnetic pole of a magnetic core  102  that is exposed toward the side of the disk. 
     Publication of Unexamined Japanese Patent Application No. Hei 6-195851 discloses the relation between the cylindrical surface  101   a  and the magnetic pole  102   a , as shown in FIG.  5 . FIG. 5 is a drawing of the slider means  101  taken from the opposite side of the surface opposing the disk. 
     In FIG. 5, A denotes the tangent line to the disk track of the center point of the magnetic pole  102   a , and B denotes the disk radius through the magnetic pole  102   a.    
     Contact region  101   b  is the region of the cylindrical surface  101   a  contacting the disk&#39;s gliding film. The contact line C 101  is defined as the line passing along the center of the contact region  101   b . The contact line C 101  is arranged so that it defines a certain angle φ with the tangent A through the center of the magnetic core  102   a  during regular contact with the disk. With such a tilted arrangement, the contact line C 101  can be arranged substantially parallel to the tangent direction of the disk track in the contact region  101   b , which reduces the gliding width (that is, the width of the contact region  101   b  in the direction perpendicular to the gliding direction). In FIG. 5, the magnetic pole  102   a  is shown as if all parts on the side opposing the disk are transparent. 
     The slider means  101 , which includes the cylindrical surface  101   a , is made of a resin material that is resistant against abrasion with the disk surface and very smooth, so that it prevents damage due to abrasion between the slider and the disk. 
     The pressing force of a spring portion  104 , which serves as a loading means, causes the contact region  101   b  of the cylindrical surface  101   a  to glide in contact with the gliding film of the disk, so that the magnetic pole  102   a  is positioned near the disk&#39;s recording film. The disk may be tilted due to surface warps and distortions, causing positional misalignments but, contact can be maintained because the gimbal  103  is deformed with respect to tilting around an axis orthogonal to the contact line C 101  in FIG. 5, and the contact region shifts with respect to tilting around an axis parallel to the contact line C 101  (rolling motion). In this situation, thermomagnetic recording is performed by applying to the recording film, which has been heated with focused laser light, a modulation magnetic field with a coil (not shown in the drawings) from the magnetic pole  102   a.    
     Together with the optical head, the slider means  101  can move over the disk in the radial direction B in FIG. 5, so that a recording magnetic field can be applied to any portion of the disk. 
     However, a conventional magnetic head as described above poses the following problems. 
     If C 102  is the line segment that passes through the center of the magnetic pole  102   a  in parallel to the contact line C 101 , then C 101  and C 102  are separated by the distance d. The value of d varies with shifts of the contact region  101   b , but it is preferable that it is zero during regular operation. 
     The reason for this is that if the disk is tilted around an axis parallel to the contact line C 101  for an angle θ, the contact line C 101  shifts, and the distance d changes. When the original of d is d 0  and the shift portion is d′, then the largest possible change of the distance between the magnetic pole  102   a  and the disk is (d′+d 0 )sin θ. 
     This change of distance causes variations in the size of the magnetic field generated by the magnetic pole  102   a , and a field that is too small may lead to recording errors. Therefore, it is necessary to run an additional current through the coil to compensate for the shift portion, which leads to an increase in the consumed power. 
     Moreover, since the gliding surface  101   a  is a cylindrical surface, the region of contact with the disk is large, and the viscous resistance with the gliding film of the disk is large, so that the load on the spindle motor increases and causes an increase in the consumed power. 
     Moreover, the cylindrical surface  101   a  easily gathers dust, and when dust has accumulated near the center of the contact region  101   b  for example, it causes a large positional change, changing the distance between the disk and the magnetic pole  102   a . Since the contact region is large, the accumulation of dust occurs relatively easily. 
     As long as the direction in which the slider means  101  moves when accessing the disk in a radial direction is not orthogonal to the contact line C 101 , it is impossible to consistently match the direction of the contact line C 101  with the direction tangential to the track in the contact region. In other words, with this configuration, when accessing the disk in a radial direction, in almost all positions in radial direction of the disk, the contact line C 101  has a certain tilt with respect to the direction tangential to the track. This means that the slide width of the contact region  101   b  (that is, the width in the direction orthogonal to the slide direction of the contact region  101   b ) is always larger than the width of the contact region  101   b  in the direction perpendicular to the contact line C 101 , which becomes a cause for a large sliding resistance and the accumulation of dust. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to solve the above problems of the prior art, and to provide a converter support structure with a simple configuration, high efficiency, and low sliding resistance, that does not easily accumulate dust. 
     The following describes a configuration of the present invention that achieves these objects. 
     A converter support structure according to a first configuration of the present invention supports a converter for recording/reproducing while moving relative to a recording medium, and includes at least two protrusion portions for maintaining the converter in a predetermined position with respect to the recording medium by contacting the recording medium. The protrusion portions are arranged substantially in parallel to the direction in which the converter moves relative to the recording medium, and a central portion of a region in which the converter interacts with the recording medium is arranged substantially on a line that passes through centers of regions where the protrusion portions contact the recording medium. 
     A converter support structure according to a second configuration of the present invention supports a converter for recording/reproducing while moving relative to a recording medium, and includes a protrusion portion for maintaining the converter in a predetermined position with respect to the recording medium by contacting the recording medium. A long axis of a region of contact between the protrusion portion and the recording medium is arranged substantially in parallel to the direction in which the converter moves relative to the recording medium, and a central portion of a region in which the converter interacts with the recording medium is arranged substantially on this long axis. 
     The converter support structures of the present invention reduce variations in the relative distance between the converter and the recording medium because at least two protrusion portions are arranged substantially in parallel to the direction in which the converter moves relative to the recording medium, and a central portion of the regions in which the converter interacts with the recording medium is arranged substantially on a line that passes through centers of regions where the protrusion portions contact the recording medium, or a long axis of a region of contact between the protrusion portions and the recording medium is arranged substantially in parallel to the direction in which the converter moves relative to the recording medium, and a central portion of a region in which the converter interacts with the recording medium is arranged substantially on this long axis. 
     In the first configuration, it is preferable that the protrusion portions are two protrusion portions. Moreover, it is preferable that the protrusion portions include a spherical surface. Moreover, in the first and in the second embodiment, it is preferable that the region where the protrusion portion contacts the recording medium is substantially elliptical. With these configurations, the sliding resistance with the recording medium is reduced and the accumulation of dust is reduced, because the region of contact between the protrusion portion and the surface of the recording medium is reduced and the sliding width is reduced. Furthermore, these improved configurations can be manufactured without posing any new difficulties. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective drawing of a magnetic head slider including a converter support structure according to a first embodiment of the present invention. 
     FIG.  2 ( a ) is a side view of the magnetic head slider in FIG.  1 . FIG.  2 ( b ) is a bottom view of the magnetic head slider in FIG.  1 . 
     FIG. 3 is a perspective view of the shape of the protrusion portions used in the magnetic head slider including the converter support structure according to a second embodiment of the present invention. 
     FIG.  4 ( a ) is a perspective view of the entire configuration of a conventional sliding magnetic head. FIG.  4 ( b ) is a perspective view showing the configuration of a slider means used in FIG.  4 ( a ). 
     FIG. 5 is a plan view of the configuration of a conventional slider means, taken from the side opposite from the disk. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following is a description of the preferred embodiments of the present invention with reference to FIGS. 1 to  3 . 
     First Embodiment 
     FIGS. 1 and 2 illustrate a magnetic head slider, that is a converter support structure according to a first embodiment of the present invention. FIG. 1 is a schematic perspective view, FIG.  2 ( a ) is a side view, and FIG.  2 ( b ) is a bottom view. 
     Numeral  1  denotes a housing portion housing a magnetic core  7  made of a ferrite for example, and a coil  8  made of copper, wherein a magnetic pole  2  is arranged so that it is exposed on the side of the housing that opposes the disk surface. Numeral  3  is a slider portion, and two protruding portions  4  and  5  are arranged on the side of the slider portion  3  that opposes the disk surface. The surfaces of the protruding portions  4  and  5  are spherical. The housing portion  1  and the slider portion  3  are made in one piece of a gliding resin, preferably a liquid crystal polymer to which a fluorine additive has been added. 
     As can be seen in FIG.  2 ( a ), the protruding portions  4  and  5  protrude a distance δ from the surface  2   a  that includes the magnetic pole  2 . Numeral  9  is a fusion pin  9  for connecting by a known means such as ultrasonic fusion to a structure similar to the gimbal  103  of the conventional example (see FIG.  4 ). The fusion pin is provided between the protruding portions  4  and  5 . Of course, depending on the system for attaching, this fusion pin  9  may be unnecessary, but in any case, the portion that couples to the gimbal  103  (the weight application point for applying a weight that forces the magnetic head slider toward the disk) is provided between the protruding portions  4  and  5 . 
     Numerals  4   a  and  6   a  in FIG.  2 ( b ) denote contact regions that result when the protruding portions  4  and  5  glide over the gliding film of the disk, which are basically small circles having the vertices of the spherical protruding portions in their centers. The line C 1  through the centers of the contact regions  4   a  and  5   a —that is, the line through these vertices—is the line of contact with the disk during regular operation. The protruding portions  4  and  5  are arranged so that this contact line C 1  passes through the center of the magnetic pole  2 . A is the tangent line to the disk track in the center point of the magnetic pole  2 , and B is the disk radius through the center of the magnetic pole  2 . 
     As in the conventional example, the contact line C 1  is arranged so that it defines a certain angle φ ( with the disk tangent A through the center of the magnetic pole  2 , and the contact line C 1  forms small angles close to zero with the tangents to the disk tracks in the protruding portions  4  and  5 . 
     The following is an explanation of the operation of the first embodiment of the present invention. 
     The pressing force of a loading means that is similar to the one shown in the prior art example acts at the position of the fusion pin  9  and causes the contact regions  4   a  and  5   a  of the protruding portions  4  and  5  to glide in contact with the gliding film of the disk, so that the magnetic pole  2  is positioned near the disk&#39;s recording film. The operation against tilts and displacements due to warps and twists in the disk surface is basically the same as in the conventional example, but since the contact line C 1  passes through the center of the magnetic pole  2  during regular operation, the distance d 0  that was explained for the conventional example becomes 0, which considerably reduces distance variations between the magnetic pole  2  and the disk and particularly enhances the efficiency of the magnetic field per coil current. 
     Furthermore, because of the two contact points, the contact region is smaller than that of the cylindrical surface  101   a  of the prior art example, which reduces the viscous resistance and the load of the spindle motor. Also, since contact is established in two points only, the chances of accumulating dust are greatly reduced. Because the contact regions  4   a  and  5   a  are substantially circular, even when the contact line C 1  does not match any disk track tangent in the protruding portions  4  and  5 , there is hardly any variation of the contact width (that is, the width of the contact region in the direction perpendicular to the disk gliding direction), regardless of the value for φ, which allows stable gliding with a small load. 
     The smaller the curvature radius of the spherical surfaces is, the smaller is the shift of the contact line C 1  and thus the distance variations between the magnetic pole  2  and the disk surface when the disk is tilted, but the durability deteriorates. As was ascertained experimentally, from the viewpoint of durability a curvature radius of about R=10 mm is preferable, more preferable is a curvature radius of 10 mm or greater. 
     The size δ of the protrusion portion should be as small as possible because this increases the conversion efficiency, but, as has already been pointed out for the prior art example, since the slider portion  3  and the housing portion  1  are linked with a certain obliqueness against the disk, portions other than the regular gliding portions, for example the corner portions of the housing portion  1 , may come into contact with the disk, depending on the radius R. Consequently, there is a minimum value for the size δ of the protrusion portion, which depends on the design. For a curvature radius of about 10 mm, the value of δ should be about 30 to 60 μm. 
     Second Embodiment 
     FIG. 3 is a perspective view illustrating the shape of the protruding portion of the magnetic head slider in a converter support structure according to a second embodiment of the present invention. The overall configuration of the magnetic head slider in this embodiment is the same as that of the first embodiment shown in FIGS. 1 and 2, so that a detailed explanation has been omitted here. In this embodiment, the spherical protruding portions  4  and  5  serving as the protruding portion of the slider portion  3  are replaced by two protruding portions  6  as shown in FIG. 3, whose long axes (x-axis direction) are aligned with the contact line C 1 . According to this embodiment, the contact region between the protruding portion  6  and the disk surface is substantially elliptical, and its long axis is aligned with the contact line C 1 . 
     The effect of this embodiment is basically the same as that of the first embodiment, but by using the elliptical surface  6  and aligning its long axis with the contact line C 1 , the contact pressure can be reduced by enlarging the contact area without any danger of enlarging the contact width (that is, the width of the contact region in the direction perpendicular to the disk gliding direction). As a result, the durability of both the slider and the disk is increased, while suppressing the accumulation of dust. As in the first embodiment, it is preferable that the curvature radius of the protruding portion  6  of this embodiment is at least 10 mm with respect to the direction perpendicular to the contact line C 1  (y-axis direction), and also the same design values for the protrusion portion amount can be used. 
     The second embodiment has been explained by way of an example where two protruding portions  6  were formed in the slider portion  3 , but it is also possible if there is only one protruding portion  6 . This is because it is possible to hold the contact pressure below a certain tolerance value even with only one protruding portion, if, compared to the protruding portions  4  and  5  of the first embodiment, the contact region of one protruding portion becomes comparatively large such as the protruding portion  6  of this embodiment. 
     The shape of the contact region is not limited to elliptical shapes, but can also be for example rectangular with four arced corner portions or of elongated shape with semi-circles at both ends. It is also possible to vary the surface shape of the protruding portion to achieve such a contact region. 
     The above embodiments have been explained by way of examples where the converter is a magnetic head. However, the converter support structure of the present invention is not limited to this, and the converter can also be an optical head including elements for sending and detecting light signals, or an objective lens. Another possible configuration is to mount a complete optomagnetical recording system including both magnetic head and focusing means. 
     The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof The embodiments disclosed in this application are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.