Flyback transformer device and process for preparing same

Information

  • Patent Grant
  • 6209776
  • Patent Number
    6,209,776
  • Date Filed
    Friday, December 23, 1994
    29 years ago
  • Date Issued
    Tuesday, April 3, 2001
    23 years ago
Abstract
In a flyback transformer device wherein the leads of diodes or like electronic components are connected between pairs of terminal pieces provided upright at opposite ends of a coil bobbin, the lead ends, of the components are fixedly connected to the respective terminal pieces by electric welding. A coil conductor wound around the bobbin has an end twined around the terminal piece, and the twined portion is soldered by dipping.
Description




FIELD OF THE INVENTION




The present invention relates to a flyback transformer device for use in television receivers and various display devices, and more particularly to the structure of a flyback transformer device wherein leads of electronic components are fixedly connected by electric welding to terminal pieces provided upright on a coil bobbin and a process for preparing the device.




BACKGROUND OF THE INVENTION




Flyback transformer devices


70


having coils provided in layers generally comprise, as shown in

FIG. 23

, a plurality of divided coils


74


wound around a coil bobbin


71


, and pairs of terminal pieces


73


provided upright at opposite ends of the bobbin


71


. A diode, resistor or like electronic component


6


is connected between each pair of opposed terminal pieces


73


,


73


.




Each of leads


63


,


63


extending from opposite sides of the electronic component


6


is electrically fixedly connected to the terminal piece


73


conventionally by shaping the terminal piece


73


in a Y-form as illustrated, placing the outer end of the lead


63


on the Y-shaped portion of the terminal piece


73


, crimping the Y-shaped portion to fix the lead


63


in this state and thereafter soldering the crimped portion by dipping (see, for example, Unexamined Japanese Utility Model Publication HEI 1-105383).




Another method of mounting electronic components on a coil bobbin has been proposed as shown in

FIG. 24. A

lead


63


is connected to a terminal piece


73




a


with a solder


66


as shown in

FIG. 25

by bending the outer end


63




a


of the lead


63


to an L-shape, fitting the lead end


63




a


in a cavity


65


in a post


71




a


of the coil bobbin at one side of the terminal piece


73




a


to preliminarily fix the lead


63


as held in contact with the terminal piece


73




a


and thereafter dipping the fixed portion in solder (Unexamined Japanese Patent Publication SHO 63-15668 and Examined Japanese Utility Model Publication hei 2-1171).




However, the conventional method of mounting electronic components with use of Y-shaped terminal pieces requires the work of fixing the lead by crimping the terminal piece and therefore has the problem of being complex and necessitating cumbersome work.




On the other hand, the method wherein cavities are formed in the coil bobbin not only requires a device for bending leads and a device for inserting the lead into the cavity but also makes the die for producing bobbins complex in configuration to result in an increased cost. Another problem is also encountered in that the coil bobbin becomes larger.




Further when solder dipping is resorted to for connection, the solder dipping device requires labor for maintenance. This leads to an increase in manufacturing cost.




SUMMARY OF THE INVENTION




An object of the present invention is to provide the structure of a flyback transformer device wherein the leads of electronic components are fixedly connected to terminal pieces of a coil bobbin by electric welding although this has not been practiced, and a process for preparing the device so as to overcome all the problems described above.




The leads of electronic components can be connected to the terminal pieces of the coil bobbin by electric welding firmly with great ease. This simplifies the production process and leads to an automated connecting procedure.




Another object of the invention is to provide a process for preparing a flyback transformer device which includes the steps of producing a coil bobbin having upright terminal pieces, winding a coil conductor around the coil bobbin, twining an end portion of the wound coil conductor around one of the terminal pieces, fixing a lead of an electronic component to another one of the terminal pieces by spot welding, and soldering the twined portion of the coil conductor around the terminal piece by dipping.




After the coil conductor end portion has been preliminarily fixed to the terminal piece by the conductor twining step of the process, the solder dipping step ensures a mechanical and electrical connection between the coil conductor and the terminal piece.




Another object of the invention is to provide an apparatus for preparing flyback transformer devices which apparatus comprises an electronic component feeder, a lead cutter, a bobbin feed position determining mechanism, an electronic component transfer mechanism and an electric welder. The electronic component feeder feeds a component supply tape having a plurality of electronic components arranged at a specified pitch by paying off the tape longitudinally thereof by the specified pitch to send the components one after another to a lead cutting position. The lead cutter cuts off the electronic component in the lead cutting position at outer ends of leads to separate the component from the supply tape. The bobbin feed position determining mechanism feeds a coil bobbin toward a predetermined welding position to position a terminal piece of the coil bobbin in the welding position.




The electronic component transfer mechanism transfers the electronic component as cut off from the supply tape by the cutter toward the welding position and positions the lead of the component alongside the terminal piece of the bobbin in the welding position. The electric welder comprises a welding head movable toward or away from the welding position, and a pair of electrode pieces projecting from the welding head for holding therebetween the terminal piece of the coil bobbin and the lead of the component in the welding position.




With the apparatus described, the electronic component feeder, lead cutter, bobbin feed position determining mechanism, electronic component transfer mechanism and electric welder are related to one another and operate concurrently to produce the flyback transfer device within a short cycle time.




More specifically, the component supply tape is paid off by the feeder at the specified pitch in the longitudinal direction to feed electronic components one after another to the lead cutting position. When one electronic component is set in the lead cutting position, the lead cutter operates at the same time to cut off the component at the outer ends of leads and separate the component from the supply tape. The electronic component separated from the supply tape is transported by the component transfer mechanism from the lead cutting position toward the predetermined welding position. At this time, the coil bobbin is set in the predetermined welding position by the bobbin feed position determining mechanism.




Accordingly, when the component is set in the welding position by the transfer mechanism, the component has its lead positioned on the terminal piece of the coil bobbin in the welding position while being held by the transfer mechanism.




In this state, the electric welder operates, the welding head moves toward the welding position, and the pair of electrode pieces are positioned at opposite sides of the terminal piece and the lead. The terminal piece and the lead are thereafter held from opposite sides between the pair of electrode pieces. Simultaneously with this, current is passed across the electrode pieces, whereby the lead is joined to the terminal piece by spot welding.




With the production apparatus described, the welder operates with the component lead positioned alongside the bobbin terminal piece by the transfer mechanism to electrically weld the lead to the terminal piece. This eliminates the need to preliminarily fix the lead to the terminal piece. Accordingly, the terminal piece can be shaped merely in the form of a rod, and there is no need to form lead inserting cavities in the bobbin which are conventionally necessary, nor is it necessary to bend the leads of electronic components. As a result, it is possible to compact the flyback transformer device and to reduce the manufacturing cost of the device.




Moreover, the step of electrically welding the lead to the terminal piece is executed almost simultaneously with the step of positioning the lead alongside the bobbin terminal piece by causing the component transfer mechanism to hold the component. This results in a shorter cycle time than the conventional method wherein the lead is preliminarily fixed to the terminal piece and thereafter soldered thereto.











BRIEF DESCRIPTION OF THE DRAWINGS





FIGS. 1

(


a


), (


b


) and (


c


) are a plan view, side elevation and front view, respectively, showing a coil bobbin in a flyback transformer device of the invention;





FIGS. 2

(


a


), (


b


) and (


c


) are a plan view, side elevation and front view, respectively, showing a high-tension coil as provided on the coil bobbin;





FIGS. 3

(


a


), (


b


) and (


c


) are a plan view, side elevation and front view, respectively, showing a plurality of electronic components as welded to the coil bottin.





FIG. 4

is a diagram showing a spot welding step;





FIG. 5

is an enlarged side elevation showing a terminal portion as soldered by dipping;





FIG. 6

is an overall front view showing an apparatus embodying the invention for preparing flyback transformer devices;





FIG. 7

is an enlarged fragmentary front view of the same;





FIG. 8

is a plan view of the same;





FIG. 9

is a front view showing the construction of an electronic component feeder;





FIG. 10

is a plan view of the same;





FIG. 11

is a side elevation of a lead cutter;





FIG. 12

is a perspective view of a component receiving member;





FIG. 13

is a front view for illustrating a path of movement of electronic components;





FIG. 14

is a front view of an electronic component transfer mechanism;





FIG. 15

is a side elevation partly broken away of the same;





FIG. 16

is a side elevation of an electric welder;





FIG. 17

is a front view of the same;





FIG. 18

is a plan view showing the internal construction of a welding head;





FIG. 19

is a front view of the same;





FIG. 20

is an enlarged front view showing a lead of the electronic component as positioned on a terminal piece of the coil bobbin;





FIG. 21

is an enlarged front view showing the lead and the terminal piece as held between electrode pieces of the welder;





FIG. 22

is a perspective view showing the flyback transformer device to be prepared by the production apparatus of the invention;





FIG. 23

is a perspective view showing a conventional flyback transformer device;





FIG. 24

is a view a lead preliminarily fixing step in a conventional method of producing the flyback transformer device; and





FIG. 25

is a view showing a soldering step of the method.











DETAILED DESCRIPTION OF EMBODIMENTS




Embodiments of the present invention will be described in detail with reference to the drawings.




(Construction of Flyback Transformer Device)





FIGS. 1

(


a


), (


b


) and (


c


) show the appearance of a coil bobbin


71


for use in a flyback transformer device of the invention, and

FIGS. 2

(


a


), (


b


) and (


c


) show a high-tension coil


74


as provided around the coil bobbin


71


of FIG.


1


. As illustrated, the coil


74


comprises a coil conductor


75


as wound in layers with an insulating film


76


interposed between the layers. With the present embodiment, the high-tension coil is formed in six layers. Opposite ends of conductor portion of each layer are preliminarily fixed as twined around terminal pieces


72


.





FIGS. 3

(


a


), (


b


) and (


c


) show six diodes


6




a


and one limiting resistor


6




b


as mounted on the coil bobbin


71


having the high-tension coil formed therearound. With reference to these drawings, each diode


6




a


extends between and is electrically welded to a pair of terminal pieces


72


,


72


corresponding thereto, while the limiting resistor


6




b


has a lead electrically welded to another terminal piece


72


and a lead soldered to an eyelet terminal


78


.




(Process for Preparing Flyback Transformer Device)




With reference first to

FIGS. 1

(


a


) to (


c


), metal terminal pieces


72


are implanted upright on posts


77


of a coil bobbin


71


. Used as the terminal piece


72


in the present embodiment is a brass core wire which is plated with tin.




With reference to

FIGS. 2

(


a


) to (


c


), a coil conductor


75


is next wound in six layers around the bobbin


71


with an insulating film


76


interposed between the layers. At this time, opposite ends of the conductor portion


75


of each layer are preliminarily fixed as twined around terminal pieces


72


. The number of layers in the high-tension coil differs depending on the type of coil.




As shown in

FIGS. 3

(


a


), (


b


) and (


c


), diodes


6




a


and a limiting resistor


6




b


are mounted. With reference to

FIG. 4

, the outer end of lead


63


of each diode


6




a


is held to the terminal piece


72


by being clamped between a pair of welding electrodes


40


,


40


, and a current of several milliamperes is passed between the electrodes to melt the surfaces of the terminal piece


72


and lead


63


and join them together by spot welding. The terminal piece


72


and the lead


63


of the diode


6




a


thus joined together by spot welding have a sufficient joint strength and are also electrically connected together. As already stated, one lead end of the limiting resistor


6




b


is spot-welded to the terminal piece


72


in the same manner as above, while the other lead end is preliminarily fixed to an eyelet terminal


78


as engaged therewith.




After the diodes


6




a


and the limiting resistor


6




b


have been mounted in place in this way, the spot welds between the terminal pieces


72


and the leads


63


of the diodes


6




a


, the coil conductor portions


75


twined around other terminal pieces


72


and the connection between the lead of the resistor


6




b


and the eyelet terminal


78


are dipped in a solder bath (not shown) at the same time for soldering, whereby the welded portions of the terminal pieces


72


and leads


63


and the conductor twined portions are covered with solder


67


as shown in FIG.


5


. Although the coil conductor


75


is covered with an insulating coating, the coating is removed by the heat of solder when dipped in the solder bath, so that the conductor


75


and the terminal piece


72


are electrically connected together. The spot weld between the terminal piece


72


and the lead


63


of each diode


6




a


is further reinforced with the solder. The lead of the resistor


6




b


is connected to the eyelet terminal


78


electrically more reliably also by the solder.




Although the terminal piece


72


used in the present invention has a rectangular cross section, this is not limitative, but the section can be circular, or elliptical or otherwise shaped as desired.




In the case of the flyback transformer device described, the lead of the diode


6




a


can be fixedly connected to the terminal piece


72


easily by spot welding. This facilitates automation of the connecting procedure, further leading to the advantage of obviating the need, for example, to bend the diode lead to an L-form. Further with such a type of devices that coil bobbins of different sizes are used, the diode mounting step can be easily executed using a jig for cutting the leads of diodes to a suitable length immediately before mounting, so that the diodes need not be worked on in advance.




Furthermore, the coil conductor twining step preliminarily fixes the end of the conductor


75


to the terminal piece


72


, the step of joining the lead


63


of the diode


6




a


to the terminal piece


72


by spot welding secures the diode


6




a


to the terminal piece


72


, and the solder dipping step mechanically and electrically connects the coil conductor


75


to the terminal piece


72


simultaneously with establishment of a mechanical and electrical connection between the lead


63


of the diode


6




a


and the terminal piece


72


. These steps are therefore advantageous in effecting a sequence of operations automatically.




(Construction of Apparatus for Preparing Flyback Transformer Device)




Next, a production apparatus for acutally preparing the flyback transformer device of the above construction will be described in detail with reference to the drawings concerned. As shown in

FIG. 22

, the flyback transformer device


7


having superposed layers and to be prepared by the apparatus includes a coil bobbin


71


for forming a high-tension coil


74


thereon. A plurality of barlike terminal pieces


72


are provided at each end of the bobbin. An electronic component


6


, which is a diode, is provided between the pair of terminal pieces


72


,


72


. The component


6


has leads


63


,


63


which are fixedly connected to the respective terminal pieces


72


by electric welding.




Overall Construction




With reference to

FIGS. 6

to


8


, arranged on a frame


90


are an electronic component feeder


1


, lead cutter


2


, electronic component transfer mechanism


3


, electric welder


4


and bobbin feed position determining mechanism


5


. Each of these devices operates under the control of a control unit


8


having a microcomputer. A welding power source device


81


is connected to the welder


4


. Incidentally, two electric welders


4


which are identical inconstruction are provided at opposite sides of the bobbin feed position determining mechanism


5


.




A component feed reel


61


for paying off a component supply tape


62


is attached to the left side of the frame


90


. The tape separated from electronic components is guided by a tape discharge guide


92


and a tape discharge chute


9


and collected in a tape container baox


91


. As shown in

FIG. 10

, the supply tape


62


includes a multiplicity of electronic components


6


arranged at a specified pitch and having leads


63


,


63


the outer ends of which are fixedly affixed to two tape segments


62




a


,


62




a


extending in parallel.




The electronic component feeder


1


operates to pay off the component supply tape


62


from the reel


61


at the pitch of compnents in the longitudinal direction and send the components


6


one after another to a position where the leads are cut by the lead cutter


2


, intermittently by a distance at a time which distance corresponds to the pitch of components arranged. The lead cutter


2


removes the electronic component


6


set in the cutting position from the supply tape


62


by cutting opposite ends of the leads


63


,


63


. The bobbin feed position determining mechanism


5


holds a coil bobbin


71


on the frame


90


shown in

FIG. 7

at a right end portion thereof, transports the bobbin


71


leftward to a position opposed to the electric welders


4


and thereafter repeats an intermittent feed operation to bring opposed pairs of terminal pieces


72


,


72


one after another to a predetermined position for welding by the electric welders


4


.




The electronic component transfer mechanism


3


holds the electronic component


6


removed from the supply tape


62


by the lead cutter


2


and transfers the component


6


rightward to a position opposed to the welders


4


to position its leads


63


,


63


alongside the respective terminal pieces


72


,


72


of the bobbin


71


in the welding position. Each of the electric welders


4


comprises a pair of electrode pieces


42


,


42


projecting from a welding head


41


which is movable toward and away from the welding position. The terminal piece


72


of the coil bobbin


71


in the wedling position and the lead


63


of the component


6


in position are clamped by the electrode pieces


42


from opposite sides.




A detailed description will be given of the construction and operation of the component devices or mechanisms of the apparatus.




Electronic Component Feeder


1






With reference to

FIGS. 9 and 10

, the component feeder


1


comprises a pair of toothed feed wheels


12


,


12


for feeding the electronic components


6


on the supply tape


62


to the lead cutting position intermittently by a distance (pitch) at a time, and tape guides


11


,


11


for guiding the movement of the tape


62


toward an inlet side of the feed wheels. Each of the feed wheels


12


is formed along its periphery with feed teeth


13


resembling sawteeth and engageable with the leads


63


of components


6


on the tape


62


, the pitch of teeth


13


being equal to the pitch of components


6


.




As shown in

FIG. 10

, a shaft


10


carrying the component feed wheels


12


has mounted thereon a ratchet wheel


14


integral with one of the feed wheels


12


. A pawl


15


is in engagement with the tooth of the wheel


14


to provide a ratchet mechanism for rotating the feed wheels


12


toward the component feed direction (clockwise direction) intermittently at a specified pitch. One-way clutch


16


is coupled to the shaft


10


to prevent reverse rotation of the feed wheels


12


and apply a predetermined frictional torque to the wheels


12


when they rotate forward.




As shown in

FIG. 9

, the shaft


10


has further attached thereto a ratchet drive plate


18


for driving the feed wheels


12


toward the component feed direction. The ratchet drive plate


18


is biased by a tension spring


19


toward a direction opposite to the feed direction (i.e., counterclockwise direction). To drivingly rotate the ratchet drive plate


18


in the feed direction, a reciprocating block


102


is attached to a rod of an actuator


17


and carries a push bolt


101


screwed therethrough and bearing at its forward end against an end portion of the drive plate


18


.




Accordingly, when the reciprocating block


102


is advanced rightward by the operation of the actuator


17


, the push bolt


101


advances away from the ratchet drive plate


18


at the same time. Consequently, the drive plate


18


rotates counterclock only through a predetermined angle under the action of the tension spring


19


. At this time, the feed wheels


12


remain at rest by being prevented by the ratchet mechanism from rotating counterclockwise with the above-mentioned rotation. The operation of the actuator


17


thereafter retracts the reciprocating block


102


leftward, causing the push bolt


101


to drive the ratchet drive plate


18


clockwise, whereby the feed wheels


12


are rotated clockwise, i.e., toward the component feed direction, through a predetermined angle.




As a result, the electronic components on the tape guides


11


are fed to the lead cutting postion, one at a time by the intermittent rotation of the feed wheels


12


. The angle through which the feed wheels


12


are rotated at a time is adjustable by the the position of the push bolt


101


relative to the reciprocating block


102


which position is determined by screwing the bolt, whereby the amount of the tape


62


to be fed at a time can be made to accurately match the pitch of components.




Lead Cutter


2






The lead cutter


2


comprises, as shown in

FIG. 11

, an upper blade


22


having a cutting edge at each of two cutting positions and two lower blades


23


,


23


for cutting the leads


63


,


63


of the component


6


at their outer end portions. The upper blade


22


is fixed to a lift block


26


, while the lower blades


23


,


23


are fixedly positioned at a predetermined level. Connected by shafts


27


,


27


to the lift block


26


is an actuator


25


for driving the block


26


downward, whereby the upper blade


22


engages with the lower blades


23


to cut the leads


63


of the electronic component


6


.




Disposed below the lead cutting position is a component receiving member


21


for receiving the component


6


separated from the supply tape, at the base ends of the leads


63


,


63


. The component receiving member


21


is mounted on the reciprocating block


102


constituting the component feeder


1


; and is in a stand-by position immediately below the upper blade


22


when to cut the leads as seen in

FIG. 9. A

ball plunger


24


is coupled to the component receiving member


21


. When tightened up, the ball plunger


24


reliably fixes the receiving member


21


to the reciprocating block


102


.




With reference to

FIG. 12

, the receiving member


21


has a pair of recesses


28


,


28


spaced apart by a predetermined distance W


1


for the leads


63


,


63


of the component


6


to fit in. The component


6


is accommodated in the space between the recesses


28


,


28


. The receiving member


21


is formed in one side thereof opposite to the recessed side (


28


) with a pair of recesses


29


,


29


which are spaced apart by a distance W


2


different from the distance W


1


so as to handle electronic components of different size when mounted as turned upside down on the reciprocating block


102


.




To separate off components of different size, the upper blade


22


is removably attached to the lift block


26


, while the position of the lower blades


23


is adjustable according to the width of the upper blade


22


.




When the upper blade


22


is lowered from the position shown in

FIG. 9

for cutting the lead, the reciprocating block


102


is retracted as stated above to position the component receiving member


21


below the upper blade


22


, and the electronic component separated from the supply tape


62


by cutting falls onto the receiving member


21


. Subsequently, with the advance of the block


102


to rotate the ratchet drive plate


18


counterclockwise, the receiving member


21


moves with the component placed thereon to the broken-line position of

FIG. 9

to deliver the component to the electronic component transfer mechanism


3


as shown in FIG.


13


.




Electronic Component Transfer Mechanism


3






With reference to

FIGS. 14 and 15

, the electronic component transfer mechanism


3


is attached to a mount plate


93


provided upright on the frame


90


and is reciprocatingly movable horizontally. The mechanism


3


has two pairs of chuck members


32


,


32


which pairs are spaced apart by a distance in accordance with the. length of the electronic component for gripping the respective leads


63


.




Two guide shafts


37


,


37


extending horizontally in parallel to each other are supported by the mount plate


93


. A reciprocating block


36


is slidable on the guide shafts in engagement therewith. An actuator


38


is disposed between the mount plate


93


and the block


36


for reciprocatingly driving the block


36


.




The reciprocating block


36


is provided with a vertical ball screw


33


, which carries a lift block


34


in screw-thread engagement therewith. The ball screw


33


is coupled to a servomotor


30


by pulley means


35


. The ball screw


33


is drivinly rotatable forward or reversely by the servomotor


30


, whereby the lift block


34


is moved upward or downward. The two pairs of chuck members


32


,


32


are attached to the lift block


34


. An actuator


31


is coupled to the chuck members


32


to open or close these members.




With reference to

FIG. 13

, the advance of the reciprocating block


102


moves the electronic component


6


on the receiving member


21


to below the chuck members


32


,


32


of the transfer mechanism


3


, whereupon the lift block


34


of the transfer mechanism


3


lowers, causing the chuck members


32


,


32


to hold the leads


63


,


63


of the component


6


as indicated in broken lines in FIG.


15


.




Next, the lift block


34


rises to raise the component


6


, and the reciprocating block


36


horizontally moves to a position above the welding position of the electric welders


4


. The lift block


34


thereafter lowers, whereby the component


6


held by the chuck members


32


,


32


is positioned alongside a pair of terminal pieces


72


on the coil bobbin


71


in the welding position as shown in FIG.


20


.




With the component transfer mechanism


3


described, the servomotor


30


is used as a drive source for the vertical movement, so that the stop position of the vertical movement can be determined as desired. Furthermore, the use of the ball screw


33


as the drive mechanism assures high positioning precision.




Bobbin Feed Position Determining Mechanism


5






The bobbin feed position determining mechanism


5


comprises, as shown in

FIGS. 7

,


8


and


16


, a rail


56


mounted on the frame


90


, a slide base


51


having a pair of arms


52


,


52


projecting therefrom for embracing the rail


56


from opposite sides, slide drive means


53


for reciprocatingly moving the slide base


51


along the rail


56


, and a bobbin mount shaft


54


supported on the slide base


51


by a support member


55


. The bobbin mount shaft


54


is removably attached to the support member


55


so as to be readily replaceable for handling bobbins of different size.




The coil bobbin


71


as fitted to the mount shaft


54


as shown in

FIG. 16

, is moved from the bottin mounting position shown in

FIG. 7

to the welding position shown in

FIG. 13

by the operation of the slide drive means


53


. The slide drive means is adapted to reciprocatingly drive the slide base


51


by rotating a ball screw forward or reversely by a servomotor so as to position the bobbin


71


, as mounted on the shaft


54


, in place with high accuracy.




The electronic component


6


held by the chuck members


32


,


32


of the transfer mechanism


3


is lowered toward the coil bobbin


71


set in the welding position as shown in

FIG. 13

to position the leads


63


of the component


6


alongside the desired pair of terminal pieces


72


on the bobbin


71


as shown in FIG.


20


.




The electric welders


4


to be described below perform a welding operation on the coil bottin


71


transported from the bobbin mounting position to the welding position to connect one electronic component


6


to the coil bobbin


71


. During the following period before the second component


6


is brought to the welding position by the transfer mechanism


3


, the bobbin feed position determining mechanism


5


positions the next pair of terminal pieces


72


to be welded at the welding position by moving the bobbin


71


by a small distance (e.g., 1 mm to 3 mm) equal to the pitch of terminal pieces


72


.




After the second component


6


has been welded to the bobbin


71


by the welders


4


, the position determining mechanism


5


similarly repeats the above movement until a predetermined number of pairs of components


6


are completely welded.




Electric Welder


4






With reference to

FIGS. 16 and 17

, each of the electric welders


4


has a slide block


49


mounted on the frame


90


and slidable toward or away from the welding position. The welding head


41


is mounted as inclined at a predetermined angle on the slide block


49


by means of a position adjusting block


44


. Two guide shafts


43


,


43


project downward from the bottom of the welding head


41


and slidably extend through the position adjusting block


44


. A level adjusting screw


45


is provided between the welding head


41


and the position adjusting block


44


. The level of the welding head


41


on the block


44


is adjustable by manipulating the screw


45


.




The position adjusting block


44


is connected to the outer end of a rod of an actuator


46


mounted on the slide block


49


as inclined at the same angle as the welding head


41


. The operation of the actuator


46


reciprocatingly moves the position adjusting block


44


and the welding head


41


as inclined. The welding head


41


has projected therefrom the above-mentioned pair of electrode pieces


42


,


42


. The welding head


41


is moved toward the coil bobbin


71


in the welding position by the operation of the actuator


46


, with the result that the pair of electrode pieces


42


,


42


are positioned at opposite sides of the lead


63


and the terminal piece


72


in the welding position to hold them.




Coupled to the slide block


49


is a position adjusting actuator


47


for horizontally moving the slide block


49


when coil bobbins


71


of different shape are to be handled. For such bobbins, the level adjusting screw


45


is also turned to alter the level of the welding head


41


.




The electrode pieces


42


,


42


are made of a material which is suitably determined in view of electric conductivity, hardness, etc. in accordance with the material of the leads and terminal pieces to be welded. According to the present embodiment, a special alloy is used which is prepared by adding chrominum, zirconium, etc. to copper.





FIGS. 18 and 19

show the interior construction of the welding head


41


. A slide body


409


is in engagement with a first arm


407


mounted on the frame


90


and slidable horizontally relative to the arm. The slide body has a second arm


408


projecting therefrom. Thw two electrode pieces


42


,


42


are attached to the respective arms.




Fixed to the first arm


407


is an actuator


48


which has a rod connected by a connecting rod


401


to a pressure shaft


402


at its base end, the shaft


402


extending through the slide body


409


. The pressure shaft


402


has a forward end on which an adjusting screw


400


is screwed. A knob


404


is integral with the head of the screw


400


. A tube


406


projects from a side portion of the slide body


409


. A coiled compression spring


403


is provided between the pressure shaft


402


and the tube


406


for biasing the slide body


409


rightward relative to the pressure shaft


402


. Tension springs


405


provided between the first arm


407


and the pressure shfat


402


bias—this shaft


402


leftward.




The first arm


407


is provided with terminals


411


,


412


for passing current between the pair of electrode pieces


42


,


42


. These terminals are connected to the aforementioned welding power supply device


81


. A limit switch


410


is provided along the path of movement of the connecting rod


401


. The limit switch


410


is turned on when the pressure shaft


402


is moved rightward by being pulled by the actuator


48


, and current is pased between the pair of electrode pieces


42


,


42


in response to the resulting ON signal.




With the pair of electrode pieces


42


,


42


arranged at opposite sides of the lead and the terminal piece, the pressure shaft


402


is driven rightward by the actuator


48


against the tension springs


405


, whereupon the slide body


409


is driven rightward through the compression spring


403


, with the result that the left electrode piece


42


projecting from the slide body


409


is brought toward the right electrode piece


42


to clamp the lead and the terminal piece between the two electrode pieces


42


,


42


.




The actuator


48


is further driven also after the slide body


409


has come to a halt to compress the spring


403


. The slide body


409


is pressed rightward by the repellent force of the spring


403


. This pressure acts to press the left electrode piece


42


projecting from the slide body


409


against the right electrode piece


42


.




As a result, the lead


63


of the electronic component


6


and the terminal piece


72


of the bobbin


71


in the welding position are held between the pair of electrode pieces


42


,


42


under pressure as shown in FIG.


21


. Immediately thereafter, the limit switch


410


operates to pass current between the electrode pieces


42


,


42


. This produces Joule heat due to contact resistance at the portions where the electrode pieces are in contact with the lead


63


and with the piece


72


. The Joule heat joins the lead


63


to the terminal piece


72


by spot welding.




With the electric welder


4


, the knob


404


is turned to adjust the initial amount of compression of the spring


403


, whereby the clamping pressure to be exerted by the pair of electrode pieces


42


,


42


on the lead and terminal piece can be set at a suitable value.




When a capacitor type welding power source is used as the power source device


81


, satisfactory results can be obtained by setting the current passing capacity at 2 to 3 kA and current passing time at 1 to 3 msec. More satisfactory results can be expected if a welding power source of the inverter type is used.




According to the present embodiment, two electric welders


4


,


4


are arranged at opposite sides of the wlding position as shown in

FIG. 8

to weld the respective leads


63


,


63


of the electronic component


6


. The two welders need to be energized with a slight time lag therebetween to prevent the electronic compoent from breaking. With the present invention, therefore, a distributor is used to connect a common power supply to the welders


4


,


4


alternatively.




With the apparatus described for preparing flyback transformer devices, electronic components can be connected to coil bobbins with a reduced number of steps. This serves to greatly reduce the production cost of flyback transformer devices. Use of electric welding to make fixed connections eliminates the need for a complex transformer structure for preliminarily fixing the electronic component lead to the terminal piece to realize coil bobbins of reduced size.




The above description of embodiments is given for the illustration of the present invention and should not be interpreted as limiting the invention defined in the appended claims or reducing the scope thereof. The construction of the components of the present device and apparatus is not limited to those of the embodiments but can of course be modified variously by one skilled in the art without departing from the sprit of the invention as defined in the claims.




For example, with the foregoing electric welder


4


, one of the electrodes


42


is fixed to the welding head


41


, with the other electrode piece


42


made movable to clamp the lead and the terminal piece, whereas the two electrode pieces


42


,


42


can be driven at the same time for opening or closing.



Claims
  • 1. A process for preparing a flyback transformer device comprising:forming a coil bobbin having upright terminal pieces; winding a coil conductor around the bobbin in at least one layer; twining each of two opposite ends said coil conductor around a respective upright terminal piece of said coil bobbin; providing at least one electronic component with leads; fixing each lead in the at least one electronic component to a respective upright terminal piece by spot welding; and soldering said leads of said at last one electronic component, said upright terminal pieces, and opposite ends of said coil conductor, by dipping in solder, wherein the portion of the coil conductor twined around the terminal piece and the portions of the leads welded to the terminal pieces are soldered at the same time by dipping.
  • 2. The process for preparing a flyback transformer device as set forth in claim 1, wherein said each of opposite ends of said coil conductor are covered with an insulating coating when twined around said respective upright terminals, and wherein in said soldering step, said insulating coating is removed by heat of the solder so that an electrical connection is made between said each of opposite ends of said coil conductor and the respective upright terminal piece, such that in said soldering step, said ends of said coil conductor are mechanically and electrically connected to respective terminal pieces simultaneously with establishment of a mechanical and electrical connection between said leads of said at least one component and respective upright terminal pieces.
  • 3. The process for preparing a flyback transformer device as set forth in claim 2, wherein said coil conductor is wound in a plurality of layers, with each layer having two opposite ends for attaching to respective terminal pieces.
Priority Claims (2)
Number Date Country Kind
4-227142 Aug 1992 JP
4-290601 Oct 1992 JP
Parent Case Info

This is a division of application Ser. No. 08/110,775 filed Aug. 23, 1993 now U.S. Pat. No. 5,396,696.

US Referenced Citations (4)
Number Name Date Kind
3631298 Rousseau Dec 1971
3917892 Kawaguchi et al. Nov 1975
3981428 Przybylla Sep 1976
4050132 Wieland Sep 1977