Abstract:
Disclosed is a ramp unit attached within a casing housing a magnetic disc, and making a magnetic head standby, the ramp unit including: a ramp main body guiding and holding the magnetic head retreated from a surface of the magnetic disc; and a sleeve member integrally provided with the ramp main body and having a tap hole to fix the ramp main body relative to the casing with screws, and further a magnetic disc apparatus using this ramp unit is disclosed.

Description:
CROSS-REFERENCE TO THE INVENTION  
       [0001]     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2004-90674, filed on Mar. 25, 2004; the entire contents of which are incorporated herein by reference.  
       BACKGROUND  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to, for example, a ramp unit retreating a magnetic head at a tip portion of an arm moving on a surface of a magnetic disc, and to a magnetic disc apparatus including this ramp unit in a casing thereof.  
         [0004]     2. Description of the Related Art  
         [0005]     A magnetic disc apparatus is using a magnetic disc as a recording medium, performing a record and playback of information, and the magnetic disc is held and rotated by a hub of a disc motor, and thereby, the record and playback of information to/from the magnetic disc is performed.  
         [0006]     In this magnetic disc apparatus, a magnetic head is prevented from being contacted with the magnetic disc by a cushion of air moving together with the magnetic disc. However, when the magnetic disc is start rotating from a static state, the not enough cushion of air can be obtained, and therefore, a friction between the magnetic head and a surface of the magnetic disc is occurred for a certain distance.  
         [0007]     From these reasons, a ramp unit is used to retreat the magnetic head from the surface of the magnetic disc, while the disc drive is not in operation (for example, refer to the following Patent Document 1).  
         [0008]     The ramp unit is resin parts molded by pouring plastic ramp unit material into a mold for injection molding, or assembling parts of a resin part and a metal sleeve. This ramp unit is fixed with a screw to a base portion such as a cover or a base from one side of either above or below.  
         [0009]     Meanwhile, a casing to house the ramp unit together with the magnetic head and the magnetic disc, is composed of the base and the cover covering thereon, and they are assembled by inserting screws into holes provided at the respective parts, and fastening to a female screw portion provided at the other part.  
         [0010]     Namely, to attach the ramp unit and to connect the base and the cover, it is required to prepare the separate holes respectively, and to attach with the separate screws. Therefore, it is required to prepare an attachment area and a connection area for these separately, and it inhibits a miniaturization of the apparatus or the parts, and a reduction of a number of parts.  
         [0011]     [Patent Document 1] Japanese Patent Laid-open Application No. 2001-23325  
         [0012]     As described above, in the conventional magnetic disc apparatus, when the parts are assembled, the ramp unit is fixed to the base with the screw at first, and then, the base portion being a built-in parts and the cover are to be fastened with screws separately. Therefore, it causes increases of a number of processes of attachment and connection thereof, and the number of parts. In addition, it is necessary to prepare the attachment area or the connection area thereof separately, and there is a problem that the miniaturization of the apparatus cannot be performed.  
       SUMMARY  
       [0013]     The present invention is made to solve these problems, and the object thereof is to provide a ramp unit and a magnetic disc apparatus contributing to a miniaturization of an apparatus as a whole and a reduction of a number of parts to be used, and enabling a reduction of cost.  
         [0014]     A ramp unit according to an aspect of the present invention is the ramp unit attached within a casing housing a magnetic disc, and making a magnetic head standby, the ramp unit including: a ramp main body guiding and holding the magnetic head retreated from a surface of the magnetic disc; and a sleeve member integrally provided with the ramp main body and having a tap hole fixing the ramp main body relative to the casing with a screw.  
         [0015]     Besides, a magnetic disc apparatus according to an aspect of the present invention, including: a magnetic disc; a casing housing the magnetic disc; a magnetic head moving mechanism including an arm and a magnetic head supported by the arm, and moving the magnetic head on a surface of the magnetic disc by the arm; a ramp main body guiding and supporting the magnetic head retreated from the surface of the magnetic disc by the magnetic head moving mechanism; a sleeve member integrally provided with the ramp main body, and having a tap hole to fix the ramp main body relative to the casing with the screw; and screws fastening the sleeve member and the casing together, with the tap hole of the sleeve member.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is an exploded perspective view showing a magnetic disc apparatus according to an embodiment of the present invention.  
         [0017]      FIG. 2  is a perspective enlarged view showing a ramp unit shown in  FIG. 1 .  
         [0018]      FIG. 3  is a plan enlarged view showing the ramp unit shown in  FIG. 1 .  
         [0019]      FIG. 4  is a sectional enlarged view showing a part of the magnetic disc apparatus shown in  FIG. 1 .  
         [0020]      FIG. 5  is a plan view showing a sleeve member shown in  FIG. 4 .  
         [0021]      FIG. 6  is a side view showing the sleeve member shown in  FIG. 4 .  
         [0022]      FIG. 7  is a sectional view taken along the line A-Aa of the sleeve member shown in  FIG. 5 .  
         [0023]      FIG. 8  is a sectional view taken along the line B-Ba of the sleeve member shown in  FIG. 6 . 
     
    
     DETAILED DESCRIPTION  
     Description of Embodiments  
       [0024]     Embodiments of the present invention will be described with reference to the drawings, but these drawings are provided only for an illustrative purpose and by no means are intended to limit the present invention.  
         [0025]     In a ramp unit according to an aspect of the present invention, a sleeve member integrally provided with a ramp main body functioning as a retreat portion of a magnetic head, has a tap hole to fix the ramp main body to a casing with a screw. The ramp main body is sandwiched between a base and a cover composing the casing from an axial direction, screws are screwed into the tap hole from the upper side of the cover and the lower side of the base, and thereby, a fixing of the ramp main body to the casing and a connection of the base and the cover composing the casing are performed at the same time. Herewith, it is not required to prepare areas for screwing screws separately to fix the ramp main body and to connect the base and the cover, and it contributes to a miniaturization of an apparatus as a whole, and a reduction of a number of parts to be used, and enables a reduction of cost.  
         [0026]     Further, a magnetic disc apparatus according to an aspect of the present invention includes a base and a cover which can attach a sleeve member so as to be sandwiched from upper and lower sides in the axial direction, the base and the cover are separately fastened together into the tap hole of the sleeve member with screws from the respective sides, and thereby, it is enabled to reduce the screw parts and to make it thinner, in addition, to make an assembling of the casing rapid.  
         [0027]     Here, the above-stated sleeve member may have a structure including a flange portion used for a positioning when the ramp main body is attached to the casing, together with a positioning hole provided at an upper surface of the ramp main body. Herewith, the ramp unit can be automatically disposed at a specified position on the base in the casing by using a robot arm, and so on, and thereby, an assembling efficiency of the ramp unit can be improved.  
         [0028]     Besides, the above-described casing may include the base and the cover to attach the sleeve member so as to be sandwiched from the upper side and the lower side in the axial direction, and it may be structured by fastening the base and the cover together into the tap hole of the sleeve member with screws separately from the respective sides. Herewith, the screw parts can be reduced for the attachment of both the base and the cover of the casing relative to the ramp unit.  
         [0029]     Further, the above-stated sleeve member may have a cylindrical shape, and include a rotation arresting portion relative to the ramp main body formed on a part of an outer peripheral surface either in flat, in concave, or in convex. Herewith, an idling of the sleeve member relative to the ramp main body can be prevented, when the screw is screwed into the tap hole of the sleeve member, and the connection between the ramp main body and the casing by screws can be ensured.  
         [0030]     Besides, the above-stated flange portion may include a cut-out portion cutting out a part thereof to sandwich the outer peripheral surface thereof, and therefore, the cut-out surface can be utilized for a gripping, a transference and the positioning, and so on, for the attachment, of the ramp unit by the robot arm, and so on.  
         [0031]     Namely, generally speaking, by using the sleeve member integrally provided with the ramp main body and having the rotation arresting portion, the fixture of the ramp main body to the base, and so on, and the connection of the base and the cover composing the casing are made by fastening together with the screws at the same area, and thereby, it becomes possible to miniaturize the apparatus as a whole and to reduce the number of parts to be used.  
         [0032]     In considering the above, hereinafter, the embodiment of the present invention is described in detail with reference to drawings.  FIG. 1  is a perspective view showing an exploded magnetic disc apparatus according to an embodiment of the present invention. As shown in the drawing, the magnetic disc apparatus includes, a base  11 , an arm  12 , a magnetic disc  13 , a ramp unit  14 , a top yoke  15 , and a cover  16 , and so on.  
         [0033]     On the base  11 , the arm  12 , the magnetic disc  13 , the ramp unit  14 , and the top yoke  15  are provided, the cover  16  is covered from above, and thereby, the inside of the cover  16  is shut out from the outside. A casing K of this magnetic disc apparatus is composed of the base  11  and the cover  16 .  
         [0034]     The arm  12  is composing a head sub assembly, has a magnetic head performing a record and playback of data at the tip portion, and is rotatably supported on the base  11  by a bearing unit  17 . This arm  12  is driven by a voice coil motor, and moves between above a surface of the magnetic disc  13  and the ramp unit  14 . A magnetic head moving mechanism which moves the magnetic head supported by the arm  12  above the surface of the magnetic disc  13 , is composed of these parts.  
         [0035]     The magnetic disc  13  is sandwiched between a hub (not-shown) rotating centering around a motor shaft and a damper  18 . A motor for driving the magnetic disc  13  is composed of magnets attached to the hub and coils disposed around them.  
         [0036]     The ramp unit  14  is to be attached within the casing K housing the magnetic disc  13 , and has a role as a retreating position to guide and hold the magnetic head retreated from the position on the surface of the magnetic disc  13  to the outside until an operation is started, so that the magnetic head does not to crash and scratch the surface of the magnetic disc  13  by a vibration, or the like, while the magnetic disc  13  stops the operation. When the operation is started, the ramp unit  14  also has a role to retreat the magnetic head to the position different from the surface of the magnetic disc  13 , until the rotation of the magnetic disc  13  reaches a minimum speed to let the magnetic head float above the surface of the magnetic disc  13 .  
         [0037]     The top yoke  15  is a part of the voice coil motor driving a base portion of the arm  12  via the bearing unit  17 . Inserting holes  21 ,  22  for screws  19 ,  20  are bored at positions facing each other of the base  11  and the cover  16 . These screws  19 ,  20  are possible to be screwed from both above and below directions to the ramp unit  14  through the inserting holes  21 ,  22 .  
         [0038]     The details of the ramp unit  14  are shown in  FIG. 2  and  FIG. 3 .  FIG. 2  is a perspective view of the ramp unit  14 , and  FIG. 3  is a plan view of the ramp unit  14 .  FIG. 4  is a longitudinal sectional view of a substantial part of the ramp unit  14  in a state assembled to the casing K. This ramp unit  14  has a long pentagonal shape of a deformed type as a whole from an attached circumstance within the casing K, and so on.  
         [0039]     The ramp unit  14  is composed of a ramp main body  14   a  made of a resin having a low friction coefficient and a good lubricating characteristic, for example, a liquid crystalline polymer such as a polyacetals, and a sleeve member  14   b  made of metal (for example, SUS, and soon) partially surrounded by the ramp main body  14   a . Namely, the sleeve member  14   b  is integrally provided with the ramp main body  14   a . The ramp main body  14   a  is to guide and support the magnetic head retreated from the surface of the magnetic disc  13 .  
         [0040]     For example, the sleeve member  14   b  is put in a mold for injection molding, and the polyacetals as resin ramp material are poured around the sleeve member  14   b . Herewith, the ramp unit  14  is formed by an insert molding of the sleeve member  14   b.    
         [0041]     The ramp unit  14  is provided at a peripheral portion of the magnetic disc  13  on the base  11 . On one side surface of the ramp main body  14   a , an inclined guide  23  being a guide surface in an inclined state to guide a tip portion of the arm  12 , is formed from an end portion at the near side of the sleeve member  14   b  to the other end portion. The ramp unit  14  (ramp main body  14   a ) is to retreat the magnetic head moved by the magnetic head moving mechanism composed of the head sub assembly, the voice coil motor, and so on, from the surface of the magnetic disc  13 .  
         [0042]     The inclined guide  23  slidably guide the tip portion of the arm  12  or a continuously provided magnetic head supporting member so as to smoothly take up and retreat the magnetic head (not-shown) from the surface of the magnetic disc  13 . The inclination and the length of the inclined guide  23  are set so as to take up the magnetic head smoothly.  
         [0043]      FIG. 5  and  FIG. 6  are a plan view and a side view of the above-stated sleeve member  14   b . Besides,  FIG. 7  is a sectional view taken along a line A-Aa of the sleeve member  14   b  in  FIG. 5 , and  FIG. 8  is a sectional view taken along a line B-Ba of the sleeve member  14   b  in  FIG. 6 . This sleeve member  14   b  has a cylindrical shape as a whole, and ring shaped flange portions (flange)  24 ,  25  having predetermined thicknesses are provided at outer peripheries of above and below both end portions thereof. At outer peripheries of the respective flange portions  24 ,  25 , flat cut-out surfaces  24   a ,  25   a  for positioning, cut out substantially in parallel, are formed.  
         [0044]     Besides, at a substantially center portion in an axial direction of the sleeve member  14   b , a ring portion  26  as a rotation arresting portion is projectingly provided. At an outer periphery of the ring portion  26 , a pair of flat cut-out surfaces  26   a  cut out substantially in parallel for rotation arresting are formed respectively. The outer periphery of the sleeve member  14   b  including the ring portion  26  is surrounded by the ramp main body  14   a  made of the polyacetals after the above-described insert molding. Therefore, the sleeve member  14   b  is rotation arrested relative to the ramp main body  14   a  by the cut-out surfaces  26   a . As the rotation arresting portions, in addition to providing the flat cut-out surfaces  26   a  at the ring portion  26 , for example, a part of the outer peripheral surface of the sleeve member  14   b  may be processed into a concave or convex state.  
         [0045]     In an inner periphery of a cylindrical hole of the sleeve member  14   b , a tap hole  27  for a female screw is thoroughly formed. This tap hole  27  has a tap diameter that the screws  19 ,  20  shown in  FIG. 1  are possible to be screwed. Namely, the sleeve member  14   b  has the tap hole  27  to fix the ramp main body  14   a  relative to the casing K with screws. The screws  19 ,  20  fasten the sleeve member  14   b  and the casing K together from outside of the casing K with this tap hole  27  of the sleeve member  14   b.    
         [0046]     On the ramp main body  14   a , a positioning hole  28  as shown in  FIG. 2  and  FIG. 3  is formed at a position departed from the sleeve member  14   b . This positioning hole  28  is used when the ramp unit  14  is gripped (sandwich) to be transferred and positioned to a predetermined position within the casing K, with the cut-out surfaces  24   a  of the flange portion  24 . Namely, these positioning hole  28  and the cut-out surfaces  24   a  of the flange portion  24  are used as a portion gripped by a robot arm, and so on.  
         [0047]     The ramp unit  14  composed of the sleeve member  14   b  and the ramp main body  14   a  is assembled within the casing K as follows. At first, the above-stated ramp unit  14  is placed on the base  11 . At this time, the tap hole  27  of the sleeve member  14   b  is accorded with the inserting hole  22  of the base  11 .  
         [0048]     Next, after the setting of various housing parts such as the magnetic disc  13  and the arm  12  is confirmed, the cover  16  is placed over the base  11 . At this time, the inserting hole  21  of the cover  16  is accorded with the upper portion of the tap hole  27  of the sleeve member  14   b . Herewith, the respective positions of the inserting holes  21 ,  22 , and the tap hole  27  are accorded. The screws  19 ,  20  are thus respectively screwed into the tap hole  27  of the sleeve member  14   b  through the respective inserting holes  21 ,  22  from the upper side of the cover  16  and the lower side of the base  11 .  
         [0049]     Consequently, the ramp unit  14  is fixed within the casing K via the sleeve member  14   b  and the screws  19 ,  20  screwed together mutually. Namely, the sleeve member  14   b  is used both for fixing the ramp main body  14   a  into the casing K, and for the connection of the base  11  and the cover  16  composing the casing K.  
         [0050]     Therefore, in this ramp unit  14 , it is not necessary to prepare an extra area for the above-stated fixing or connection on the casing K. As a result, the miniaturization of the magnetic disc apparatus becomes possible. Further, the setting number of the screws  19 ,  20 , the tap hole  27 , and so on, can be reduced, and therefore, the workability of assembling is improved and the cost down can be realized.  
         [0051]     As described above, according to the ramp unit  14  of this embodiment, the tap hole  27  is provided to fix the ramp main body  14   a  to the casing K with screws, at the ramp main body  14   a  functioning as the retreating portion of the magnetic head. Consequently, when the screws  19 ,  20  are screwed into this tap hole  27 , the fixing of the ramp main body  14   a  to the casing K and the connection of the base  11  and the cover  16  composing the casing K can be performed at the same time.  
         [0052]     As a result, it is not necessary to prepare areas to screw the screws  19 ,  20  separately for the fixing of the ramp main body  14   a  and the connection of the base  11  and the cover  16 , and therefore, the miniaturization of the apparatus as a whole, the reduction of the number of parts to be used, and the reduction of cost are enabled.  
         [0053]     Besides, according to the magnetic disc apparatus of this embodiment, the screws  19 ,  20  are screwed in the tap hole  27  of the ramp unit  14 , and thereby, the sleeve member  14   b  and the base  11  and the cover  16  of the casing K can be fastened together. Consequently, the working efficiency of assembling of the magnetic disc apparatus can be improved.  
         [0054]     The present invention is not limited to the specific forms described here with the illustrations, but it is to be understood that all the changes and modifications without departing from the range of the following claims are to be included therein.