Abstract:
This invention relates to a flexible printed circuit board mounting structure capable of easily soldering an FPC to a printed circuit board. When the flexible printed circuit board (FPC) is soldered upright on the printed circuit board, the FPC holder is secured in the mounting hole of the printed circuit board by the pressure of the elastic portion, to thereby hold the FPC holder by a support projection cut and raised from a chassis. In this state, the terminal portion of the FPC is soldered to the edge portion of the mounting hole of the printed circuit board, thereby ensuring electrical connection of each circuit pattern of the FPC and the printed circuit board.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a recording/reproducing device using a recording/reproducing disk such as a floppy disk and a hard disk and, more particularly, to a structure for mounting a flexible printed circuit board (hereinafter referred to as FPC) for transmitting a signal to a magnetic head, and a recording/reproducing device using the same. 
     2. Description of Related Art 
     A recording/reproducing device using a conventional structure for installing an FPC, as shown in FIG. 11, is provided with a square through hole  51   c  in the corner section of a chassis  51  made of a metal plate. Below the chassis  51 , a printed circuit board  52  is attached to partly cover the underside thereof. 
     The printed circuit board  52  has a couple of long mounting holes  52   a  in the corner section. On the underside of the printed circuit board  52 , a circuit pattern  52   b  (FIG. 12) is provided. On the chassis  51 , a head device  55  is located for writing an information signal into, or reading an information signal from, an unillustrated magnetic disk. The head device  55  has a carriage  56  which can reciprocate in the direction (in the direction of the arrow A in the drawing) of magnetic disk insertion or removal. The carriage  56  is comprised of a head mounting base  56   a  located below, and an upwardly slidable head support arm  57 . At the forward end of the head mounting base  56   a  and the head support arm  57 , a pair of magnetic head  58  are mounted in mutually opposite positions. 
     The pair of magnetic heads  58  are connected with one end of the FPC&#39;s  60  and  61 ; the other ends of the FPC&#39;s  60  and  61  are free ends. 
     On the free end side of the FPC&#39;s  60  and  61 , terminal portion  60   a  and  61   a  are formed in an exposed state. 
     An FPC holder  62  is a member made of a resin having a U-shaped cross section, and is provided with lower end portions  62   b  and  62   c  projecting downwardly for insertion into the through hole  51   a  of the chassis  51 . 
     In the FPC&#39;s  60  and  61  connected to the pair of magnetic head  58 , the terminal portions  60   a  and  61   a  on the free end side thereof are attached to the FPC holder  62 , and fitted to the mounting hole  52   a  of the printed circuit board  52 , being connected to the circuit pattern  52   b  (FIG.  12 ). As shown in FIG. 12, the FPC holder  62  fitted with a couple of FPC&#39;s  60  and  61  is inserted through the through hole  51   a  of the chassis  51 , with the lower end portions  62   b  and  62   c  of the FPC holder  62  inserted in the mounting hole  52   a  of the printed circuit board  52 . 
     The terminal portions  60   a  and  61   a  of the FPC&#39;s  60  and  61  and the circuit pattern  52   b  on the printed circuit board  52  are fixedly attached and electrically conducted by solder  63 . 
     The recording/reproducing device  50  using the mounting structure of the FPC&#39;s  60  and  61  has a drawing: if the FPC holder  62  has an excess play when the FPC&#39;s  60  and  61  are soldered to the printed circuit board, either one or both of the terminal portions  60   a  and  61   a  of the FPC&#39;s  60  and  61  will fail to deviate from the position of the circuit pattern  52   b  of the printed circuit board  52 , resulting in defective soldering of both or either one of the FPC&#39;s  60  and  61 . 
     As an example of improvement effected to solve the problem of defective soldering, a recording/reproducing device  70  using the FPC mounting structure proposed by the applicant will be described with reference to FIGS. 13 and 14. 
     The printed circuit board  72  is provided with long mounting holes  72   a ,  72   a  formed as shown in FIG.  13 . 
     The same number of guide holes  51   a  and  51   b  as the number of the FPC holders  82  are formed mutually adjacently into an about long-hole shape. 
     The chassis  51  has support projections  51   c  and  51   e  formed by cutting and raising a part of the guide holes  51   a  and  51   b . These support projections  51   c  and  51   e  are formed in mutually deviated positions so that extensions prior to cutting and raising will not be overlapped with each other. 
     On the forward end of FPC&#39;s  80  and  81  a plurality of terminal portions  80   a  and  81   a  formed of a copper foil or other are exposed on the lower side. On the upper side of the terminal portions  80   a  and  81   a , a circuit pattern extended into the base sections  80   c  and  81   c  of the FPC&#39;s  80  and  81  is routed in a laminate shape. The end portion on the base sections  80 c and  81   c  side of the FPC&#39;s  80  and  81  is connected to the magnetic head  58 . 
     On the back side of the FPC&#39;s  80  and  81  where the terminal portions  80   a  and  81   a  are not exposed, a double-faced adhesive tape is affixed, by which the FPC&#39;s  80  and  81  are attached to a later-described FPC holder  82 . 
     The FPC holder  82  is a resinous member generally formed in a flat-plate shape. At the center of its one side, an approximately rectangular projecting portion  82   a  is formed projecting outwardly. The lower part of the projecting portion  82   a  is tapered. The lower end portion  82   b  is disposed to the lower portion, and terminal portions  80   a  and  81   a  of the FPC&#39;s  80  and  81  are attached. 
     On the lower portion of the FPC holder  82 , in FIG. 13, first and second arm portions  82   d  and  82   e  are extended from the right and left sides in the direction of a central projecting portion  82   a.    
     In the drawing, on the right side surface of the FPC holder  82  an elastically deformable hook-shaped retaining portion  82   g  is formed. 
     Furthermore, at the lower corners of the FPC holder  82 , guide portions  82   h  and  82   j  are formed for positioning the terminal portions  80   a  and  81   a  of the FPC&#39;s  80  and  81 . The terminal portions  80   a  and  81   a  positioned by the guide portions  82   h  and  82   j  are attached by a double-faced adhesive tape on the FPC holder  82 . 
     The forward end of the FPC&#39;s  80  and  81  is bonded on the FPC holder  82 . To attach this FPC holder  82  to the printed circuit board  72 , the lower end portion  82   b  of the FPC holder  82  is inserted into the guide holes  51   a  and  51   b  of the chassis  51 , and the portion between the first and second arm portions  82   d  and  82   e  is fitted on the support projections  51   c  and  51   e . And also the lower end portion  82   b  of the FPC holder  82  and the terminal portions  80   a  and  81   a  are inserted in position in the mounting hole  72   a  of the printed circuit board  72 , thereby aligning the terminal portions  80   a  and  81   a  with the circuit pattern of the printed circuit board  72 . 
     The guide portions  82   h  and  82   j  of the FPC holder  82  are brought into contact with the surface of the printed circuit board  72 , so that the insertion of the FPC holder  82  into the guide holes  51   a  and  51   b  and the mounting hole  72   a  stops thereat. 
     At this time, the retaining portions  82   g ,  82   g  are snapped into engagement with the guide holes  51   a  and  51   b . The FPC holder  82  is fixedly retained in the guide holes  51   a  and  51   b.    
     With the FPC holder  82  thus snapped into engagement with the guide holes  51   a  and  51   b , the terminal portions  80   a  and  81   a  of the FPC&#39;s  80  and  81  protruding out of mounting hole  72   a  of the printed circuit board  72  and the circuit pattern of the printed circuit board  72  are connected by solder  63 , to thereby electrically conduct the terminal portions  80   a  and  81   a  and the circuit pattern of the printed circuit board  72 , thus assembling the mounting structure of the FPC&#39;s  80  and  81 . 
     In the recording/reproducing device  70  using the FPC  80  and  81  mounting structure proposed, there will be left a 0.1 mm or larger clearance between the FPC holder  82  and the terminal portions  80   a  and  81   a  located in the mounting hole  72   a  of the printed circuit board  72 . The solder  63  will flow into this clearance, failing in substantially securely attaching to a proper strength by soldering. 
     Therefore, it is likely that the terminal portions  80   a  and  81   a  of the FPC&#39;s  80  and  81  and the circuit pattern of the printed circuit board  72  can not reliably be electrically connected. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide an FPC mounting structure capable of easy soldering without producing a clearance between the FPC and the printed circuit board, and a recording/reproducing device using the same. 
     As a first means for solving at least one of the above problems, the present invention has a flexible printed circuit board having a terminal portion forming portion at which a terminal portion is formed in an exposed state on one side of the forward end an FPC holder having an elastic portion on the surface side and capable of mounting the terminal forming portion on the back side, a printed circuit board having a mounting hole, and a chassis located above the printed circuit board and having a guide hole for inserting the terminal portion into the mounting hole of the printed circuit board; the chassis being provided with a support projection formed by cutting and raising the edge portion of the guide hole. The FPC holder fitted with the terminal forming portion is inserted into the guide hole to elastically hold the elastic portion of the FPC holder in contact with the support projection, thereby pressing the terminal portion of the FPC against the edge portion of the printed circuit board mounting hole. 
     Furthermore, as a second means for solving the problem, the elastic portion is provided with an retaining engagement projection for preventing disengagement on the lower end of the FPC holder. 
     Furthermore, as a third means for solving the problem, the present invention uses the aforesaid flexible printed circuit board mounting structure. 
     The foregoing object and other objects, features and advantages of the present invention will become more apparent and understandable from the following detailed description thereof, when read in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of one embodiment of a recording/reproducing device according to the present invention; 
     FIG. 2 is an enlarged perspective view showing a major portion of one embodiment of the recording/reproducing device according to the present invention; 
     FIG. 3 is am exploded perspective view showing a major portion of an FPC holder mounting structure in one embodiment of the recording/reproducing device according to the present invention; 
     FIG. 4 is a top view of the FPC holder in one embodiment of the recording/reproducing device according to the present invention; 
     FIG. 5 is a left side view of the FPC holder shown in FIG. 4; 
     FIG. 6 is a plan view of the FPC holder shown in FIG. 4; 
     FIG. 7 is a bottom view of the FPC holder shown in FIG. 4; 
     FIG. 8 is a right side view of the FPC holder shown in FIG. 4; 
     FIG. 9 is a sectional view of the FPC holder shown in FIG. 4; 
     FIG. 10 is a sectional view showing the FPC holder in a mounted state in one embodiment of the recording/reproducing device according to the present invention; 
     FIG. 11 is an exploded perspective view showing a major portion of a conventional recording/reproducing device; 
     FIG. 12 is a sectional view of a major portion of the conventional recording/reproducing device; 
     FIG. 13 is an exploded perspective view of a major explaining the FPC mounting structure of the recording/reproducing device proposed and 
     FIG. 14 is a sectional view of a major portion of the recording/reproducing device shown in FIG.  13 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 1 to  10 , a flexible printed circuit board (FPC) mounting structure and a recording/reproducing device  10  using the same according to the present invention will be described. 
     In the recording/reproducing device  10 , as shown in FIG. 1, a square printed circuit board  13  with a circuit pattern  13   b  (FIG. 10) formed on the surface is attached upside down within a metal frame body  12  which is open in the upper part. 
     Above the printed circuit board  13  there is mounted a metal chassis  15  on which a turntable  14  for loading and driving a recording disk  100  indicated by a single-dot chain line in FIG. 2 is rotatably installed. 
     Near the center of this chassis  15 , a plastic carriage  18  is mounted, on which a pair of magnetic heads  16  and  17 , upper and lower, are mounted in opposed positions. For reciprocally moving the carriage  18  in the direction of the arrow A in FIG.  2 , a stepping motor  19  (see FIG. 1) is mounted on the chassis  15 . 
     In the carriage  18 , as shown in FIG. 2, a head mounting base  18   a  is mounted on the lower side and, above the head mounting base  18   a , a head support arm  21  fixedly attached by a plurality of screws  23  through a flexible plate spring  22  is swingably mounted. 
     The pair of magnetic heads  16  and  17  are attached on the head mounting base  18   a  and the opposite surfaces  18   b  and  21   a  near the forward end of the head support arm  21  through a mounting plate  24 . 
     The carriage  18  thus constituted is supported on a guide shaft  25 , along which it can reciprocate in the direction of the arrow A. 
     Next, as shown in FIGS. 4 to  9 , the FPC holder  28  is made of a flat plate-like resin material. On the lower end side at the center of its both surfaces, there is formed an approximately U-shaped cutout  28   b . And surrounded by the cutout  28   b  is an approximately rectangular, flexible elastic portion  28   a  having a free end at the forward end. 
     On the free end side of the elastic portion  28   a , a projection-like retaining portion  28   c  is provided, protruding slightly outwardly from the surface. On the lower end of the FPC holder  28 , first and second arm portions  28   d  and  28   e  are bent to extend from the right and left sides in FIGS. 4 to  6  toward the elastic portion  28   a  located at center. 
     Furthermore, rectangular guide portions  28   h  and  28   j  are formed projecting as shown in FIG. 7, at the lower corner on the back side of the FPC holder  28 . Furthermore, at about the center of the back side, a columnar retaining engagement projection  28   k  is formed. 
     Furthermore, the FPC holder  28  has a lower end portion  28   f  decreased in plate thickness at the forward end. 
     Next, the FPC&#39;s  26  and  27  are formed of a flexible plastic film as shown in FIG. 3; and an unillustrated circuit pattern is formed with its surface insulated by laminating on the film. 
     On the surface of the forward end of the FPC&#39;s  26  and  27 , there are provided terminal forming portions  26   b  and  27   b  comprising a plurality of rectangular rounds formed of a copper foil with the terminal portions  26   a  and  27   a  exposed. The upper end portion of the terminal portions  26   a  and  27   a  is connected to the circuit pattern connected to each round. 
     The FPC&#39;s  26  and  27  are connected at one end side to the pair of magnetic heads  16  and  17 , and guided and attached at the other end side by the guide portions  28   h  and  28   j  on the back side of the FPC holders  28 ,  28 , so that the retaining engagement projections  28   k ,  28   k  of the FPC holders  28 ,  28  are hold through the FPC&#39;s  26  and  27 . 
     On the printed circuit board  13 , long mounting holes  13   a ,  13   a  are formed. The terminal portions  26   a  and  27   a  of the FPC&#39;s  26  and  27  and the lower end portion  28   f  of the FPC holder  28  are bonded together and inserted into the mounting holes  13   a ,  13   a.    
     The chassis  15  mounted on the printed circuit board  13  is provided with the same number of rectangular guide holes  15   a  and  15   b  which are mutually adjacently formed as the number of the FPC holders  28 ,  28  in positions corresponding to the mounting holes  13   a  of the printed circuit board  13 . 
     Furthermore, the chassis  15  is provided with support projections  15   c  and  15   e  formed by cutting and raising a part of the edge portion facing the guide holes  15   a  and  15   b.    
     Next, mounting of the FPC  26  and the FPC holder  28  used in the recording/reproducing device  10  will be explained with reference to FIG.  10 . 
     The FPC  27  having the same constitution as the FPC  26  is mounted in the same manner, and therefore will not be explained. 
     As shown in FIG. 10, in the terminal forming portion  26   b  of the FPC  26 , a double-faced adhesive tape not shown is affixed on the side (back side) where the terminal portion  26   a  is not exposed, and the terminal forming portion  26   b  is attached by this double-faced adhesive tape to the surface between the guide portions  28   h  and  28   j  of the FPC holder  28 . 
     At this time, the retaining engagement projection  28   k  of the FPC holder  28  fits in an unillustrated hole formed in the FPC  26 , thereby properly position the FPC  26 , together with the guide portions  28   h  and  28   j , on the FPC holder  28 . In this state, the lower ends of the terminal portions  26   a  and  27   a  are flush with the lower end  28 f of the FPC holder  28 . 
     Next, to attach the FPC holder  28  thus fitted with the FPC  26  to the printed circuit board  13 , the lower end portion  28   f  of the FPC holder  28  is inserted into the guide hole  15   b  of the chassis  15 , and the support projection  15   c  is fitted in the arm portions  28   d  and  28   e  of the FPC holder  28 . Then, while sliding the elastic portion  28   a  of the FPC holder  18  in contact with the support projection  15   c , the lower end portion  28   f  of the FPC holder  18  and the terminal portion  26   a  of the FPC 26  are both inserted into the mounting hole  13   a  of the printed circuit board  13 . 
     The lower ends of the guide portions  28   h  and  28   j  of the FPC holder  28  are brought into contact with the surface of the printed circuit board  13 , thus stopping further insertion of the arm portions  28   d  and  28   e  of the FPC holder  28  over the support projection  15   c , and insertion of the lower end portion  28 f of the FCP holder  28  and the terminal portion  26   a  of the FPC  26  into the mounting hole  13   a.    
     At this time, the retaining portion  28   c  of the elastic portion  28   a  is engaged with the bent portion of the support projection  15   c , and the terminal portion  26   a  attached on the lower end portion  28   f  of the FPC holder  28  is pressed into contact, without a clearance, with the edge portion of the mounting hole  13   a  with an elastic force (reaction) of the retaining portion  28   c , whereby the whole body of the FPC holder  28  is fixed in an inclined position. 
     Therefore, each round of the terminal portion  26   a  of the FPC  26  is in contact in a given position with the circuit pattern  13   b  of the printed circuit board  13 . 
     With the FPC holder  28  fitted in the mounting hole  13   a  of the printed circuit board  13 , the terminal portion  26   a  of the FPC  26  of a portion protruding out of the mounting hole  13   a  of the printed circuit board  13  and the circuit pattern  13   b  of the printed circuit board  13  are bonded by solder  40 , so that the terminal portion  26   a  and the circuit pattern  13   b  of the printed circuit board  13  are electrically conducted, thus completing mounting of the FPC  26 . 
     In the mounting structure of the FPC&#39;s  26  and  27  thus constituted and the recording/reproducing device  10  using the mounting structure, the carriage  18  is moved in the direction of the arrow A by the rotation driving force from the stepping motor  19  with the pair of magnetic heads  16  and  17  held in contact with the upper and lower sides of the magnetic disk  100  shown in FIG.  2 . That is, while the carriage  18  reciprocates in the radial direction of the recording disk  100 , the recording disk  100  is turned on the turntable  14  to perform recording, reproducing and deletion of information on the upper and lower sides of the recording disk  100 . 
     The FPC mounting structure of the present invention is provided with an FPC having a terminal forming portion with a terminal portion formed, being exposed on one side of the forward end thereof, an FPC holder having an elastic portion on the surface side and capable of mounting the terminal forming portion on the back side, a printed circuit board having a mounting hole, and a chassis located above the printed circuit board and having a guide hole for inserting the terminal portion into the mounting hole of the printed circuit board. The chassis is provided with a support projection formed by cutting and raising the edge portion of the guide hole. The FPC holder fitted with the terminal forming portion is inserted into the guide hole so that the elastic portion of the FPC holder is in elastically contact with the support projection. And the terminal portion of the FPC is pressed against the edge portion of the mounting hole formed in the printed circuit board, whereby the elastic portion of the FPC holder is held in contact with the side wall of the chassis in the mounting hole. Therefore, the FPC holder is pressed by the reactive action of the elastic portion against one side of the mounting hole of the printed circuit board, thereby facilitating soldering of the FPC to the printed circuit board without any effect of clearance and accordingly enabling reliable electrical connection. 
     Furthermore, since the retaining engagement projection is provided on the lower end of the FPC holder for preventing disengagement, the elastic portion can simply snap the FPC holder into connection with a part of the chassis. Accordingly the FPC can be held with a pressure on one of the printed circuit board in the state of preventing disengagement, thus enabling easy soldering. 
     Furthermore, since the recording/reproducing device of the present invention uses the FPC mounting structure above-described, the FPC can easily be attached to the printed circuit board through the FPC holder.