Patent Publication Number: US-2009225469-A1

Title: Method of manufacturing a drive apparatus, connection circuit board, and drive apparatus using the same

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a method of manufacturing a drive apparatus that rotationally drives a recording medium using a motor, a connection circuit board that connects a motor for rotationally driving a recording medium and a control circuit board for the motor, and a drive apparatus that rotationally drives a recording medium using a motor. 
     Data can be written onto and read from a recording medium such as a magnetic disk, an optical disc, or a magneto-optical disc by a drive apparatus that rotationally drives the recording medium using a motor. A DC brushless motor or the like is normally used as the motor. 
     The overall construction of a conventional drive apparatus is shown in  FIG. 7 . 
     In the case of a hard disk apparatus, for example, a motor  5  for rotationally driving a magnetic disk  2  is assembled inside a case  6  and then the motor  5  and a control circuit board  7  are connected. 
     Note that an attachment hole  8  is formed in the case  6  at the position where the motor  5  is assembled, and an upper end portion  5   a  of the motor  5  is disposed so as to protrude out of the attachment hole  8 . 
     A connection portion for electrically connecting the motor  5  is provided at the upper end portion  5   a  of the motor  5 . 
     A plane view of the connection portion is shown in  FIG. 8  and a partial cross-sectional view of the motor is shown in  FIG. 9 . 
     Hereinafter this connection portion is referred to as the “motor FPC (Flexible Printed Circuit)  10 ”. The motor FPC  10  is a member that is provided so that tests can be carried out by the motor manufacturer who manufactures the motor before the motor is shipped (see for example, Japanese Laid-Open Patent Publication No. 2001-190056). 
     The motor FPC  10  includes a plurality of pads  12  that are respectively electrically connected to driving coils  11  of the motor  5 . The surfaces of the pads  12  are formed of solder and are connected to the driving coils  11  by printed circuits  13 . The pads  12  are exposed at the upper end portion  5   a  of the motor  5 , and connection parts  19  where the pads  12  are connected to the driving coils  11  by the printed circuits  13  are provided at positions that are not exposed to the outside of the motor. 
     The pads  12  are formed at predetermined intervals around the upper end portion  5   a  of the motor  5  and are formed so as to facilitate electrically connecting the pads  12  and carrying out tests before the motor is shipped. 
     After the motor  5  has been attached to the case  6 , the motor  5  is connected to the control circuit board  7 . The motor  5  and the control circuit board  7  are connected by an FPC (Flexible Printed Circuit)  14  as one example of a connection circuit board. 
     The form of the motor end of the FPC  14  is shown in  FIG. 10 . 
     A connection portion  14   a  in the form of a flat plate is formed at the motor end of the FPC  14 . A plurality of pads  15  that can be connected by soldering to the motor FPC  10  are formed on the connection portion  14   a.    
     Note that a connector  16  is provided at the control circuit board  7  end of the FPC  14  and is connected to a connector  17  provided on the control circuit board  7 . 
     Note that in the past, there have also been cases where the motor  5  and the FPC  14  are connected using connectors. However, compared to the demands for miniaturization and reduced thickness for hard disc apparatuses, the size in the height direction becomes too large when connectors are used. Instead, as shown in the drawings the plate-like connection portion  14   a  of the FPC  14  and the motor FPC  10  that is connected in advance by the motor manufacturer are placed on top of one another and connected. 
     The plate-like connection portion  14   a  that is formed at the motor end of the FPC  14  has a plurality of pads  15  that are formed of solder at the same positions as the pads  12  formed on the motor FPC  10 . The pads  15  of the FPC  14  are connected by printed circuits  18  so as to be connected to the corresponding terminals on the connector  16  at the other end. 
     When the FPC  14  and the motor  5  of the construction described above are connected, the plate-like connection portion  14   a  of the FPC  14  is placed on and connected to the motor FPC  10  of the motor  5  by fixing the pads with solder. 
     SUMMARY OF THE INVENTION 
     As described above, with a method where an FPC is soldered after a motor has been assembled in a drive apparatus case to connect the motor and the FPC, there is the problem that the soldering operation is difficult, leading to the risk of operation errors. 
     Solder webbing and solder bridges can be given as examples of poor connections produced by operation errors. When such poor connections are produced, there is the risk of fire or smoking due to improper insulation or an insufficient withstand voltage. 
     The present invention was conceived in view of the problem described above, and it is an object of the present invention to provide a method of manufacturing a drive apparatus that can manufacture a drive apparatus without producing poor connections when electrically connecting a motor and a control circuit board for the motor, and to also provide a connection circuit board and a drive apparatus that uses the same. 
     A method of manufacturing a drive apparatus according to the present invention manufactures a drive apparatus that rotationally drives a recording medium using a motor, the method including steps of: attaching a motor, which has been connected in advance to one end of a connection circuit board that connects the motor and a control circuit board for the motor, to a drive apparatus case; and then connecting another end of the connection circuit board to the control circuit board for the motor. 
     According to this method, since it is not necessary to connect the connection circuit board by soldering to the motor that has been assembled on the drive apparatus case, it is possible to reduce operation errors and to reduce the number of poor connections. 
     The connection circuit board may be formed in a folded-up state in advance, and after the motor that has been connected to the connection circuit board in the folded-up state is attached to the drive apparatus case, the connection circuit board may be unfolded and the other end of the connection circuit board connected to the control circuit board for the motor. 
     Here, there is the risk that the connection circuit board will get in the way if the motor is assembled in an attachment hole in the case with the connection circuit board having already been connected to the motor. However, by folding up the connection circuit board, the connection circuit board is prevented from getting in the way and it becomes possible to easily attach the motor to the attachment hole of the case. 
     Also, when the motor that has been connected to one end of the connection circuit board in the folded-up state is attached to the drive apparatus case, an upper part of the connection circuit board in the folded-up state may be covered by a cover member so that the connection circuit board in the folded-up state does not become unfolded. 
     According to this method, it is possible to prevent the connection circuit board from becoming unfolded and getting in the way. 
     Note that when the other end of the connection circuit board is connected to the control circuit board for the motor, the cover member may be removed to unfold the folded-up connection circuit board. 
     Also, the connection circuit board may be formed so as to be folded up in a normal state. 
     A connection circuit board according to the present invention connects a motor that rotationally drives a recording medium and a control circuit board for the motor, wherein the connection circuit board is constructed so that wires provided at one end of the connection circuit board are capable of being electrically connected to driving coils inside the motor, wires provided at another end of the connection circuit board are capable of being electrically connected to the control circuit board, and pads capable of being electrically connected to outside the wires are provided on the respective wires connected to the driving coils. 
     According to this construction, since it is possible to connect the connection circuit board in advance during the manufacturing of a motor, it is no longer necessary to connect the connection circuit board after the motor has been assembled on the drive apparatus case. 
     The connection circuit board may be capable of being folded, and the connection circuit board may be formed so as to be folded up in a normal state. 
     A drive apparatus according to the present invention includes: a motor that rotates a recording medium; and the connection circuit board described above that connects the motor to a control circuit board for the motor. 
     Here, the other end of the connection circuit board may be provided so as to be detachably attached to the control circuit board, and a cover member that covers an upper part of the connection circuit board in a folded-up state may be provided on the motor so that when the other end of the connection circuit board is not attached to the control circuit board, the connection circuit board in the folded-up state on the motor does not become unfolded. 
     According to the method of manufacturing a drive apparatus, the connection circuit board, and the drive apparatus according to the present invention, it is possible to reduce operation errors and to reduce the number of poor connections. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing the overall construction of a drive apparatus according to the present invention; 
         FIG. 2  is a cross-sectional view of a motor attachment part of the drive apparatus shown in  FIG. 1 ; 
         FIG. 3  is a plane view of a connection circuit board according to the present invention; 
         FIG. 4  is a partial cross-sectional view of a motor; 
         FIG. 5  is a cross-sectional view of a motor attachment part of the drive apparatus showing a state where the connection circuit board is folded up; 
         FIG. 6  is a flowchart useful in explaining a method of manufacturing a drive apparatus according to the present invention; 
         FIG. 7  is a perspective view showing the overall construction of a conventional drive apparatus; 
         FIG. 8  is a diagram useful in explaining a conventional connection portion of a motor; 
         FIG. 9  is a partial cross-sectional view of a conventional motor; and 
         FIG. 10  is a plane view of a motor end of a conventional connection circuit board. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of a drive apparatus, a connection circuit board, and a method of manufacturing the same will now be described. 
     A hard disk apparatus is one example of a drive apparatus according to an embodiment of the present invention. In the case of a hard disk apparatus, a magnetic disk is used as the recording medium. 
       FIG. 1  is a perspective view showing the overall construction of a hard disk apparatus.  FIG. 2  is a cross-sectional view showing a part of a case where a motor is attached. 
     The hard disk apparatus  30  includes, inside an apparatus case  31 , a magnetic disk  33 , a carriage arm that includes a head slider at a front end thereof, and a spindle motor  32  that rotationally drives the magnetic disk  33 . Here, a DC brushless motor is normally used as the spindle motor (hereinafter simply “motor”)  32  that rotationally drives the magnetic disk  33 . 
     The hard disk apparatus  30  is constructed by assembling the magnetic disk  33 , the carriage arm, and the spindle motor  32  mentioned above inside the apparatus case  31  (hereinafter simply “case”). 
     After these components have been assembled inside the case  31 , the motor  32  and a control circuit board  34  are electrically connected. Here, the motor  32  and the control circuit board  34  are connected by a connection circuit board  36 . 
     A control circuit (that includes a controller IC or the like) that controls the driving current flowing to the motor  32  and also a control circuit that controls the entire hard disk apparatus  30  are formed on the control circuit board  34 . 
     Note that the connection circuit board  36  for connecting the control circuit board  34  to the motor  32  is provided so as to be connected in advance to the motor  32  during the manufacturing of the motor  32 . 
     An attachment hole  41  for the motor  32  is formed in the case  31  and the motor  32  is attached so that an upper end portion  32   a  thereof protrudes out of the case  31  from the attachment hole  41 . 
     The connection circuit board  36  is provided on the upper end portion  32   a  of the motor  32 . 
     The connection circuit board  36  will now be described in detail with reference to  FIGS. 3 and 4 . 
     As one example of the connection circuit board  36 , an FPC (Flexible Printed Circuit) where copper foil is formed as wires inside a covering made of polyimide is used. Hereinafter, the connection circuit board  36  is simply referred to as the “FPC  36 ”. 
     One end of the FPC  36  is connected to the motor  32  and the other end of the FPC  36  is connected to the control circuit board  34 . 
     Printed circuits  38  that are connected to both the driving coils inside the motor  32  and the terminals of the connector are formed along the entire length of the FPC  36 . 
     One end  36   a  of the FPC  36  is formed in a shape that matches the shape of the upper end portion  32   a  of the motor  32  and is flatly disposed on the upper end portion  32   a  of the motor  32 . A through-hole  35  through which a rotational shaft portion of the motor  32  is passed is formed in the center of the end  36   a.    
     In addition, a plurality of wiring portions  44  that can be connected by direct soldering or the like to electrically connect the driving coils  11  inside the motor  32  and the printed circuits  38  are formed so as to protrude outward at the end  36   a . However, the wiring portions  44  are disposed so as to be bent when the FPC  36  is connected to the motor  32 , so that connections  45  between terminals  11   a  that extend out from the driving coils  11  and the wiring portions  44  are not visible from outside the motor  32 . 
     Note that a connector  37  is connected to the other end  36   b  of the FPC  36 . The connector  37  can be connected to a connector  39  provided on the control circuit board  34 . Accordingly, a one-touch connection can be made between the other end  36   b  of the FPC  36  and the control circuit board  34  using the connectors  37  and  39 . 
     A plurality of pads  40 , which make it possible to electrically connect the printed circuits  38  that are connected to the driving coils  11  on the outside of the motor, are formed on the end  36   a  of the FPC  36 . The pads  40  are formed of metal such as solder and are formed so as to be substantially circular in shape. By forming these pads  40 , during the manufacturing stage of the motor  32 , it is possible to test the motor before shipping by connecting (or touching) a testing apparatus or the like to the pads  40 . 
     Note that there is the risk that the FPC  36  will get in the way and make assembly difficult if the motor  32  is assembled in the case  31  with the FPC  36  having already been connected. This is because the motor  32  is assembled in the case  31  by forming the attachment hole  41  in the case  31  in advance and inserting the motor  32  into the attachment hole  41  using an automated device. 
     For this reason, the FPC  36  that is connected to the motor  32  is provided so as to be foldable so that the FPC  36  can be folded and made compact when the motor  32  is assembled in the case  31 . 
     As the method of folding, the FPC  36  may be formed in a zigzag form as shown in  FIG. 5 . 
     As the method of folding the FPC  36 , instead of folding up the FPC  36  after the FPC  36  has been formed, the FPC  36  may instead be formed in advance in a folding state. By using an FPC  36  that is foldable in advance, it is possible to keep the FPC  36  folded up in the normal state and to extend the FPC  36  as necessary by pulling upon the FPC  36 . 
     A fixed cover  46  (that corresponds to a “cover means” in the patent claims) that covers the folded FPC  36  from above may be provided on the upper end portion  32   a  of the motor  32 . 
     The fixed cover  46  is formed of composite resin or the like and functions so as to press down the folded-up FPC  36  and thereby prevent the FPC  36  from extending. Since the fixed cover  46  needs to be removed when the FPC  36  is connected to the control circuit board  34 , the fixed cover  46  may be detachably provided on the upper end portion  32   a  of the motor  32  using adhesive tape or the like. To attach the fixed cover  46  to the upper end portion  32   a  of the motor  32 , it is also possible to form the front end of the fixed cover  46  as a hook and to detachably engage this hook-shaped part on the edge of the upper end portion  32   a  of the motor  32  (not shown). 
     Note that even if the fixed cover  46  is not provided above the FPC  36 , it is possible to use a construction where the FPC  36  itself prevents the FPC  36  from becoming unfolded. 
     For example, the connector  37  that is connected to the other end of the FPC  36  may be used. In this example, by forming a first locking mechanism that engages a second locking mechanism formed in advance on the connector  37  on the FPC  36 , it is possible to engage the first and second locking mechanisms of the connector  37  and the FPC  36  in a state where the FPC  36  is folded up (not shown). 
     With this construction, since it is not necessary to provide the fixed cover  46 , there is the effect that it is possible to reduce the number of parts compared to the example where the fixed cover  46  is provided. 
     Next, a method of manufacturing the motor that uses the FPC described above will be described. 
       FIG. 6  is a flowchart useful in explaining a method of manufacturing a hard disk drive according to the present invention. 
     First, during manufacturing of the motor, the motor manufacturer connects one end of the FPC  36 , which has been folded up in the zigzag manner described above to the motor (step S 100 ). At this time, the fixed cover  46  is attached so as to prevent the FPC  36  from becoming unfolded. 
     Next, at the manufacturer of the hard disk apparatus  30 , the motor  32  to which the FPC  36  has been connected in advance is assembled in the case  31  (step S 102 ). Such assembling is carried out by using an automatic apparatus to insert the motor  32  into the attachment hole  41  formed in the case  31  so that the upper end portion  32   a  of the motor  32  protrudes outward. 
     After this, the fixed cover  46  is peeled off and the folded-up FPC  36  is pulled so as to extend. The connector  37  at the other end  36   b  of the extended FPC  36  is connected to the connector  39  of the control circuit board  34  (step S 104 ). 
     By doing so, the manufacturing of the hard disk apparatus is completed. 
     Note that in the embodiment described above, a hard disk apparatus has been described as an example of a drive apparatus. 
     However, a drive apparatus that rotationally drives a recording medium according to the present invention is not limited to a hard disk apparatus and it is possible to apply the present invention to a variety of drive apparatuses such as a CD drive, a DVD drive, an MO drive, and a floppy (registered trademark) disk drive.