Abstract:
A spindle motor structure includes a solenoid coil  1  provided above a flexible board  2  provided at one face of a base plate of FDD to align in a circumferential direction centering on one axis and a turn table covering the solenoid coil  1  and provided rotatably centering on the one axis. The spindle motor structure can provide FDD capable of achieving a reduction in cost by reducing a number of parts of PWB and the like using a silicon steel plate, i.e. silicon steel plate PWB.

Description:
BACKGROUND OF THE INVENTION 
   (1) Field of the Invention 
   The present invention relates to a spindle motor structure, particularly to a structure of a spindle motor used for driving a flexible disk drive (FDD) and a thin type flexible disk drive having the same. 
   (2) Description of the Related Art 
   Conventionally, a flexible disk drive (FDD) is used for recording information and reading information to and from a flexible magnetic disk (FD) contained in a case made of plastic. 
   According to such a conventional FDD structure, there is constituted a structure attached with individual parts with a main frame (chassis) as a base and also with regard to a spindle motor, an assembled product formed with PWB (Power board) as a base, is fixed to a base plate of the main frame by screws. 
   Therefore, according to a thin type FDD, there is constituted a structure of making a large hole at a central portion of the main frame and a design in consideration of strength of the frame is needed. 
   Further, the main frame and the PWB mounted with the spindle motor are constituted by separate parts and therefore, a dimensional tolerance is needed which is for ensuring an accuracy of attaching the spindle motor. 
   SUMMARY OF THE INVENTION 
   Hence, it is an object of the present invention to provide a spindle motor structure capable of achieving a reduction in cost by reducing a number of parts of PWB and the like using a silicon steel plate. 
   Further, it is another object of the present invention to provide a spindle motor structure capable of stabilizing the dimension of a main frame. 
   Further, it is still another object of the present invention to provide a spindle structure capable of increasing rigidity of a frame by deleting a hole for attaching PWB. 
   Further, it is yet another technical problem of the present invention to provide a spindle motor structure capable of promoting an accuracy of attaching a spindle motor. 
   Further, it is a further object of the present invention to provide a frame structure having a spindle motor having an advantage similar to that of the spindle motor. 
   Further, it is a still further object of the present invention to provide a thin type FDD having an advantage similar to that of the spindle motor. 
   According to an aspect of the present invention, there is provided a spindle motor structure which comprises a solenoid coil provided above a flexible board provided at one face of a base plate of a flexible disk drive to align in a circumferential direction centering on an axis, and a turn table covering the solenoid coil provided rotatably centering on the axis. 
   Further, according to another aspect of the present invention, there is provided a frame structure having a spindle motor, the spindle motor comprising a base plate of a flexible disk drive, a solenoid coil provided above a flexible board provided at one face of the base plate to align in a circumferential direction centering on one axis, and a turn table covering the solenoid coil and provided rotatably centering on the one axis. 
   In the frame structure having a spindle motor according to the above-described aspect, the solenoid coil is constituted by arranging a plurality of constitutions arranged at inside of the turn table and provided with wirings at winding frames prolonged in diameter directions centering on the one axis at equal angular intervals and in a shape of a concentric circle. 
   Further, according to still another aspect of the present invention, there is provided a thin type flexible disk drive which comprises a main frame, a containing and discharging mechanism contained at inside of the main frame for containing and discharging a cartridge contained with a flexible disk, a spindle motor provide at the main frame for rotating the flexible disk centering on one axis, and a head assembly movable in a radius direction of the flexible disk. The spindle motor comprises a flexible board arranged above one face of the frame and including a plurality of solenoid coils arranged at a surrounding of the one axis, and a turn table provided rotatably at the surrounding of the one axis to cover the solenoid coils. The flexible board is electrically connected to a main circuit board provided at the one face of the main frame for driving the flexible disk drive. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  is a plan view of FDD according to a related art removed of a cover thereof; 
       FIG. 2  is a plan view of FDD of  FIG. 1  removed of a disk containing and discharging mechanism comprising an eject plate and a disk holder; 
       FIGS. 3A and 3B  illustrates bottom views of FDD according to the related art and are views viewing FDD by removing PWB portion having a spindle motor; 
       FIG. 4  is a plan view of PWB of  FIG. 3 ; 
       FIG. 5  is a plan view of PWB of  FIG. 4  removed of a turn table; 
       FIG. 6  is a bottom view of a portion of attaching PWB of a main frame; 
       FIG. 7  is a plan view showing a solenoid coil board and a main circuit board of a spindle motor according to an embodiment of the present invention; 
       FIG. 8  is a plan view of a flexible disk drive according to an embodiment of the present invention removed of a cover thereof; 
       FIG. 9  is a disassembled perspective view of a flexible disk drive according to an embodiment of the present invention; 
       FIG. 10  is a disassembled perspective view of an essential portion of a flexible disk drive according to an embodiment of the present invention removed of an upper cover thereof; and 
       FIG. 11  is a disassembled perspective view of an essential portion of the flexible disk drive of  FIG. 10 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Before explaining embodiments of the present invention, in order to facilitate to understand the present invention, an explanation will be made as regards FDD according to a related art with reference to  FIGS. 1 through 6 . 
   Referring to  FIG. 1 , FDD  13  is provided with a main frame  15 , a disk containing and discharging mechanism  17 , a front bezel  19 , a head assembly  21 , and a screw type stepping motor  23 . The main frame  15  is constituted by a box type shape in which an upper portion thereof having an opening on one end side is opened. The disk containing and discharging mechanism  17  is provided to cover the upper portion of the main frame  15 . The front bezel is provided on the one end side of the main frame  15  to constitute a lid of an opening for containing FD. The head assembly is provided on a rear end side of the main frame  15  and is constituted progressably and regressably in a front and rear direction, which will be shown as up and down direction in the drawing. The stepping motor  23  drives the head assembly. 
   Referring to  FIG. 2 , the main frame  15  is provided with a PWB containing portion or attaching portion  35  having a circular through hole portion at a center thereof in order to attach PWB  25  formed on a silicon steel plate to a base plate  33  constituting a bottom portion. PWB  25  is attached to the attaching portion  35  from an outer side by screws or the like. The head assembly  21  is provided on one side of the main frame  15 . The head assembly  21  is constituted by a channel-like shape in a vertical section thereof and magnetic heads, not illustrated, are respectively provided on inner side faces thereof opposed to each other. The head assembly  21  is provided to carry out progressing and regressing movement in the front and rear direction constrained by being guided by a guide rail  27  provided on one side thereof. Further, a stepping motor  29  is provided on a side opposed to the one side of the head assembly  21  via an attaching metal piece  31 . The head assembly  21  is provided with an engaging portion engaged with a groove in a spiral shape provided at a screw rod of the stepping motor  29 . By driving the stepping motor  29 , the screw rod is rotated. In accordance with rotation of the screw rod, the head assembly  21  has the engaging portion engaged with the groove of the screw rod so as to be moved in the front and rear direction. Further, a main board  34  having an L-like shape is provided on one face of the base plate  33  of the main frame  21 . 
   Referring to  FIG. 3A , the base plate  33  of the main frame  21  is provided with the PWB containing portion  35  recessed in a circular shape to contain PWB  25  as shown in  FIG. 3B . The PWB containing portion  35  is provided with a circular hole portion  37  in correspondence with a shape of a turn table of the spindle motor. The spindle motor has the turn table and notched portions  39 ,  41 ,  43  penetrating the plate face at surroundings of the hole portion  37 . The PWB containing portion  35  is recessed to be concave to an inner side centering on the circular hole portion  37 . 
   As shown in  FIG. 4 , PWB  25  is provided with a silicon steel plate  45 , a wiring pattern  47 , and a spindle motor portion  49 . The wiring pattern  47  is provided above the silicon steel plate  45  via resin or the like (not illustrated) comprising an insulating material, further, a surface thereof is covered with similar resin (not illustrated). A turn table  51  is rotatably provided to constitute the spindle motor portion  49 . 
   As shown in  FIG. 5 , an exciting coil  59  is provided above the pattern when the turn table  51  is removed. The exciting coil  59  is formed by aligning  24  pieces of solenoid coils  57  each constituted by winding a winding  55  around a coil bobbin  53 , along a circumference at equal angular intervals. Further, at a central portion thereof, there is provided a rotary or thrust bearing  61  in correspondence with a rotating shaft  63 . Further, notation  46   a  designates a soldered terminal portion and notation  46   b  designates an electronic part mounted to a wiring pattern  47 . 
   As shown in  FIG. 6 , when PWB  25  is inserted into the containing portion  35  having the recessed bottom portion and attached thereto by screws, the spindle motor structure as shown in  FIG. 2  is finished. 
   Now, an explanation will be made as regards an embodiment of the invention in reference to  FIGS. 7 through 11 . 
   As shown by  FIG. 7 , a drive board of an FDD spindle motor is provided with a flexible board  67  and a main board  71 . The flexible board  67  is formed with a solenoid coil  65 . The main board  71  is provided with a soldered connecting end portion  69  connected to the flexible board  67 . 
   The solenoid coil  65  is formed by providing windings  75  to winding frames  72  projected to outer sides in radius directions. The solenoid coil  65  is formed by being integrally formed with one face of the flexible board  67  or adhered to the one face. Although in the illustrated example, a bearing  77  is mounted to a center thereof, the bearing  77  can be removed. 
   Further, the main board  71  is provided with an L-like shape. The main board  71  is connected with the flexible board  67  via the soldered connecting portion  69 . Various electronic parts  81  are provided which are connected via a circuit pattern  79  above the main board  71 . Further, a connector  83  is provided for electrically connecting to outside at one end of the main board  71 . Further, a screw hole  85  is provided for fixing the main board  71  to a base plate of a main frame, mentioned later, at the main board  71 . 
   Referring to  FIG. 8 , FDD  87  is provided with a main frame  93 , a disk containing and discharging mechanism  95  contained in the main frame  93 , a head assembly  97  progressable and regressable in an up and down direction in  FIG. 8 , and a stepping motor  99 . 
   The main frame  93  is provided with a base plate  105 , a side plate  106 , and a rear plate  108 . The main frame  93  is provided openably and closably with an upper end portion thereof as an axis and is provided with a front bezel  91  urged to cover an opening by a spring  89  at one end thereof. The disk containing and discharging mechanism  95  is contained in the main frame  93 . The head assembly  97  is provided progressably and regressably in the up and down direction in  FIG. 8 . The stepping motor  99  is provided to move to position the head assembly  97 . 
   The disk containing and discharging mechanism  95  is provided with an eject plate  101  and a disk holder  103  provided on an inner side thereof. A cartridge containing a flexible magnetic disk is contained in a space between the disk holder  103  and the base plate  105  of the main frame  93  and above a turn table  107 . Further, the eject plate  101  and the disk holder  103  are provided to overlap. The eject plate  101  is urged in a front direction, which will be shown in a lower direction in the drawing, relative to the disk holder  103  by coil springs  104  provided on both sides of the eject plate  101 . Further, at one end of the disk holder  103 , there is provided a push lever  111  rotatable centering on a shaft  109 . A coil spring  113  is provided between the push lever  111  and the disk holder  103 . 
   When the cartridge of the flexible magnetic disk is contained, one end portion of the disk cartridge is brought into contact with one end of the lever  111  and the lever  111  is rotated in the clockwise direction centering on the shaft  109 . When the lever  111  is rotated up to a predetermined position, the lever  111  is stopped by engaging with the disk holder  103 . 
   Meanwhile, in ejecting the disk cartridge, when an eject button  114  is depressed, for example, an upward direction in the drawing, the engagement between the lever  111  and the disk holder  103  is disengaged, and by recovering force of the coil spring  113 , the lever  111  is rotated in the counterclockwise direction to thereby push out the disk cartridge. 
   In reference to  FIG. 9 , FDD  87  is constituted by providing an essential portion  115 , the disk containing and discharging mechanism  95  contained in the essential portion  115  and a cover  117  for covering an upper portion thereof. 
   In reference to  FIG. 10  and  FIG. 11 , the principal portion  115  of FDD  87  is provided with the main frame  93 , a spindle motor  119  provided above the base plate  105  of the main frame  93 , and the main board  71  provided above the base plate  105  at a surrounding of the spindle motor  119 . 
   Above the main board  71 , there is provided a reinforcing portion made of synthetic resin also serving as a guide for a flexible cable for signal from the head assembly  97 . The reinforcing portion is used to maintain strength against compression in the up and down direction. The head assembly  97  is provided at one end of the base plate  105  of the main frame  93 . One side of the head assembly  97  is inserted into a guide rail  121 . Further, the other side of the head assembly  97  is engaged with a groove portion of a drive rod  123  extended from a main body  122  of a step motor  99 . 
   A rear side of the head assembly  97  is fixed with a board  125  for electric connection by a screw  126 . The spindle motor  99  is provided at one side portion of the head assembly  97 . The spindle motor  99  is fixed to position by fastening a metal piece  127  by a screw  129 . Further, a circuit board  131  for supplying current is provided also on one side of the spindle motor  99 . Further, also the guide rail  121  is fixed to the base plate  105  along with the main board  71  by a metal piece  133 . 
   Further, an upper face of the base plate  105  is provided with a push up lever  167  for pushing up the disk cartridge in cooperation with the eject plate  103  (refer to  FIG. 9 ), an eject lever  109  and a lock releasing lever  137  for disengaging engagement with the disk holder  103 . Further, notations  136  and  138  designate cut pieces for preventing rise of level of the push up lever  167  and lock releasing lever  137 . 
   Referring to  FIG. 11 , in order to assemble the essential portion  115 , the main board  71  is fixed to the base plate  105  of the main frame  93  by a screw  139 . The attaching metal piece  133  is provided by a screw  142  to hold an inner side of a rear end of the main board  71 . The attaching metal piece  133  serves also as a fixing metal piece of the guide rail  121  of the head assembly  97 . 
   Next, the flexible board  67  formed with the solenoid coil  65  ( FIG. 7 ) is mounted to a bottom portion of the base plate  105  of the main frame  93  by aligning to a through hole  143  having a bearing  141 . The bearing  77  is provided above the center of the flexible board  67 . Further, a rotating shaft  145  of the turn table  107  is rotatably contained in the through hole via the bearing  141 . Here, the turn table  107  is mounted by aligning positions of a cut-up portion  147  provided at the base plate  105  and a groove  149  of the turn table  107 , and once the turn table  107  is mounted, the turn table  107  is rotatable. However, detachment of the turn table  107  to an upper side is hampered so far as rotational positions of the groove  149  and the cut-up portion  147  do not coincide with each other. 
   The head assembly  97  is constituted by a channel-like shape in a vertical section thereof and magnetic head elements  155  are respectively provided on inner sides of upper and lower head support pieces  151  and  153 . One side of the head assembly  97  is provided with the step motor  99  having a drive rod  123  projected to one end. The step motor  99  is fixed by fixing a metal piece  127  to a projected portion  163  provided at the base plate by a screw  165  such that an engaging portion  159  at one end of the head assembly  97  is engaged with a groove  157  provided at a screw rod  123  for driving of the step motor  99 . 
   Further, a member  166  in an S-like shape is made of plastic and is provided for guiding a cable for connecting the head assembly  97  and the main board  71  and reinforcing FDD. 
   Further, a push up lever  167  is provided rotatably around pin  169  for pushing up the contained flexible disk cartridge in an upper front direction in cooperation with the eject plate  101  ( FIG. 9 ) in ejecting the disk cartridge. And the lock releasing lever  137  is provided rotatably around pin  171  for lifting the disk holder  103  and disengaging engagement in the front and rear direction of the eject plate and the disk holder  103 . 
   As shown in  FIG. 11 , when the essential portion  115  is assembled, as shown in the plan view of  FIG. 10 , the essential portion  115  is completed. 
   Further, when the disk containing and discharging mechanism  95  is mounted onto the essential portion  115  as shown by  FIG. 9 , there is constructed the structure shown in  FIG. 8 . Further, by mounting the cover  117  as shown in  FIG. 9 , the disk drive is finished. 
   In this way, according to the embodiment of the present invention, by directly attaching the spindle motor  119  to the base plate  105  of the main frame  93  without using PWB formed above the silicon steel plate, in accordance with a change in the spindle motor structure (FG sensorless), the circuit constitution of the spindle motor PWB is simplified, the constitution can deal therewith only by the flexible board (FPC)  67  without using PWB using the silicon steel plate separately constituted conventionally and the flexible disk drive can be constructed by a thin type and simple constitution. 
   Further, according to the embodiment of the present invention, the base plate  105  of the main frame  93  is dispensed with a shape of attaching an assembled product of the spindle motor  119 , for example, a hole, the accuracy of the attaching position can be promoted and the fabrication can further be facilitated. 
   As has been explained above, according to the present invention, FDD can be provided which is capable of achieving a reduction in cost by reducing a number of parts of PWR or the like using the silicon steel plate. 
   Further, according to the present invention, FDD can be provided which is capable of stabilizing dimensions of the main frame. 
   Further, according to the present invention, FDD can be provided which is capable of strengthening the rigidity of the frame by deleting a hole of the main frame for attaching PWB. 
   Further, according to the present invention, FDD can be provided which is capable of promoting the accuracy of attaching the spindle motor by directly attaching the spindle motor to the main frame.