Patent Document

BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a high-frequency relay suitable for switching a high-frequency signal. 
   2. Description of the Related Art 
   In the related art, there is disclosed a high-frequency relay in Japanese Patent Laid-Open No. 2001-345036. In this high-frequency relay, a contact block, a sub-base block, a hinge plate block, an armature block, and so on, are disposed on a base block. The contact block moves up and down within a space enclosed by the base block and the sub-base block so as to switch on/off a transmission line. The contact block itself is operated through the hinge plate block by rotating the armature block due to excitation and demagnetization of the electromagnetic block. 
   Some typical relays may have scattering in accuracy of parts and accuracy of assembling. Thus, desired operation properties cannot be obtained. In such a case, adjustment work is required after assembling. 
   In the related-art high-frequency relay, however, there is no way of performing adjustment except deformation of an armature spring fixed to the bottom surface of the armature. That is, the force to press the contact block through a hinge spring and a support member has to be adjusted only by picking up and deforming the portion of the armature spring protruding from the armature. In addition, the adjustable range may be limited only by such adjustment at one place, so that desired operation properties cannot be obtained. Thus, this results in the occurrence of defective products. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the invention to provide a high-frequency relay in which the work of adjustment after assembling is easy and the adjustable range is so wide that desired operation properties can be obtained without occurrence of defective products. 
   As means for solving the foregoing problem, the invention provides a high-frequency relay comprising: 
   a base block having a fixed terminal insert-molded to expose a fixed contact; 
   an electromagnetic block having a coil wound around an iron core through a spool, mounted on the base block and for rotating a movable iron piece due to excitation and demagnetization; and 
   a movable block having a movable contact interlocking with a rotation operation of the movable iron piece so as to be connected with and disconnected from the fixed contact of the base block; 
   wherein the movable iron piece includes a push-in spring for pushing the movable block, the push-in spring having a fixed portion fixed to the movable iron piece, a pressure portion for applying pressure to the movable block, and a foot portion extending substantially perpendicularly to the movable block wherein an extending direction of the foot portion can be adjusted. 
   With this configuration, desired operation properties can be obtained easily only by deforming the foot portion of the push-in spring after assembling so as to change the extending direction of the foot portion with respect to the movable block. The angle of the foot portion with respect to the movable block can be changed easily and with a wide changeable range. Accordingly, the rate of occurrence of defective products can be reduced on a large scale. 
   A guide portions for guiding the foot portion of the push-in spring fixed to the movable iron piece may be formed in a side surface of the electromagnetic block. 
   Preferably, the electromagnetic block includes an adjustment portion continuous with the guide portion and capable of adjusting the extending direction of the foot portion of the push-in spring. In this case, the workability in the work of adjustment can be improved. 
   Further, the foot portion of the push-in spring may include a bent portion in a forward end portion thereof, and the bent portion is disposed in corresponding the guide portion of the electromagnetic block so that the foot portion can be elastically deformed by abutment of the bent portion against the guide portion when the movable iron piece rotates. 
   With this configuration, when the movable iron piece rotates, the foot portion can be elastically deformed over a wide range up to their bent portion in contact with the guide portion so as to apply a weak elastic force to the movable iron piece. As a result, even if the attraction of the electromagnetic block is not increased so much, the movable iron piece can be rotated smoothly. In addition, even if the elastic force of the return spring is weakened, the movable iron piece can be returned easily to its initial position through the movable block. Accordingly, the high-frequency relay can be arranged at a low price. 
   Preferably, the push-in spring includes an adjustment portion capable of adjusting a position of the pressure portion, the adjustment portion protruding from the movable iron piece. In this case, the high-frequency relay can be arranged to be easier to adjust. 
   Preferably, the electromagnetic block includes not only the guide portions but also a support recess portion capable of supporting a push-in spring of another type. In this case, parts can be standardized among relays of different types. Thus, the cost can be reduced. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of a high-frequency relay according to an embodiment of the invention; 
       FIG. 2A  is a perspective view of a base block shown in  FIG. 1 ; 
       FIG. 2B  is a plan view of the base block shown in  FIG. 1 ; 
       FIG. 3A  is a sectional view of the base block shown in  FIGS. 2A and 2B ; 
       FIG. 3B  is a partially enlarged view of  FIG. 3A ; 
       FIG. 3C  is a perspective view of  FIG. 3A  from the bottom surface side; 
       FIG. 4  is a perspective view of a return spring shown in  FIG. 1 ; 
       FIG. 5  is a perspective view of a ground plate shown in  FIG. 1 ; 
       FIG. 6A  is a perspective view of a movable block shown in  FIG. 1 ; 
       FIG. 6B  is a perspective view of  FIG. 6A  from the bottom surface side; 
       FIG. 6C  is a sectional view of  FIG. 6A ; 
       FIG. 7A  is a perspective view of an electromagnetic block shown in  FIG. 1 ; 
       FIG. 7B  is a front view of  FIG. 7A ; 
       FIG. 8A  is a perspective view from the bottom surface side, showing the electromagnetic block shown in  FIG. 1 ; 
       FIG. 8B  is a perspective view from the bottom surface side, showing a movable iron piece and a push-in spring according to another embodiment of the invention; 
       FIG. 8C  is a perspective view from the bottom surface side, showing a movable iron piece and a push-in spring according to the embodiment of the invention; 
       FIG. 8D  is a perspective view from the bottom surface side, showing an electromagnetic block in which the movable iron piece and the push-in spring shown in  FIG. 8B  have been installed; 
       FIG. 8E  is a perspective view from the bottom surface side, showing an electromagnetic block in which the movable iron piece and the push-in spring shown in  FIG. 8C  have been installed; 
       FIG. 9A  is an exploded perspective view of the movable iron piece and the push-in spring; 
       FIG. 9B  is a perspective view from the bottom surface side, showing the state where the movable iron piece and the push-in spring have been installed; 
       FIG. 10A  is a perspective view showing the state where the movable blocks and the ground plate have been mounted on the base block; 
       FIG. 10B  is a sectional view of  FIG. 10A ; 
       FIG. 11  is a sectional view of the high-frequency relay according to this embodiment; and 
       FIG. 12  is a perspective view showing the state where a casing has not yet been installed in the high-frequency relay according to the embodiment. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   An embodiment of the invention will be described below with reference to the accompanying drawings. 
     FIG. 1  shows a high-frequency relay according to this embodiment. The high-frequency relay is mainly arranged as follows. That is, a ground plate  2 , movable blocks  3  and an electromagnetic block  4  are mounted on a base block  1 , and covered with a casing  5 . 
   The base block  1  has a substantially rectangular plate-like shape as shown in  FIGS. 2A-2B  and  FIGS. 3A-3C , which is obtained by insert-molding of fixed terminals  6   a ,  6   b  and  6   c.    
   Each of the fixed terminals  6   a ,  6   b  and  6   c  is obtained by bending a conductive plate-like piece substantially at a right angle, and constituted by a fixed contact portion  7  and a foot portion  8 . Two fixed contacts  7   c  are provided in the fixed contact portion  7  of the fixed terminal  6   c  (common terminal) disposed in the central portion of the base block  1 . One fixed contact  7   a ,  7   b  is provided in the fixed contact portion  7  of the fixed terminal  6   a ,  6   b  (terminal a, b) disposed on either end portion of the base block  1 . 
   Guide walls  9  are provided erectly on the top surfaces of the opposite end portions of the base block  1 . In each of the guide walls  9  (end surface side), a substantially U-shaped retention portion  10  is formed so that an iron core  39  which will be described later can be fixed thereto by caulking narrow portions  11  on the top of the retention portion  10 . Engagement recess portions  12  are formed on the opposite sides of the retention portion  10 . Each engagement recess portion  12  has a retention recess portion  13  in its central portion. In addition, the inner and outer surfaces of each guide wall  9  (side surface side) are formed stepwise. 
   Recess portions  15  each surrounded by a protruding strip portion  14  are formed in the upper surface of the base block  1 . The ground plate  2  is mounted on the protruding strip portion  14 . The height of the protruding strip portion  14  is limited in a plurality of places so that air layers  16  (see  FIG. 3B ) can be formed between the protruding strip portion  14  and the ground plate  2  to be mounted thereon. In addition, projections  17  are formed at four places in the protruding strip portion  14  so as to serve to fix the ground plate  2 . In addition, a seal groove  18  is formed in the protruding strip portion  14  so as to prevent seal agent from invading the inside at the time of sealing work which will be described later. In addition, bridging portions  19  are formed in the protruding strip portion  14  so as to prevent the thin fixed terminals  6   a ,  6   b  and  6   c  (the plate thickness used here is about 0.18 mm) from being deformed when the contacts are switched on/off. Each of the bridging portions  19  is made as narrow as possible but wide enough to allow resin to flow at the time of insert-molding. Thus, the bridging portions  19  are designed so that the fixed terminals  6   a ,  6   b  and  6   c  are prevented from floating when the contacts are switched on/off while the exposed area of each fixed terminal  6   a ,  6   b ,  6   c  is made maximal. The opposite end portions and the central portion of the recess portions  15  project upward so as to form seat portions  20 . The fixed contact portions  7  of the fixed terminals  6  are exposed over the seat portions  20  respectively. In each seat portion  20 , not only the top surface of the fixed contact portion  7  but also its edge portion  7   d  are exposed. In addition, lock guard portions  21  for positioning a return spring  100  are formed in each recess portion  15 . 
   In each return spring  100 , an elastic tongue portion  23  is formed in a rectangular frame portion  22  by press working out of a plate-like spring material as shown in FIG.  4 . Lock portions  24  are provided to extend from the opposite sides at one end of the rectangular frame portion  22 . The base portion of the elastic tongue portion  23  is supported on the rectangular frame portion  22  through a bent portion  25 , while the elastic tongue portion  23  is made easy to deform elastically due to the function of a depressed portion  26  formed in the rectangular frame portion  22 . In addition, a displacement prevention stopper portion  27  is formed in the forward end of the elastic tongue piece  23 . Each return spring  100  is disposed in the recess portion  15  of the base block  1  with the lock portions  24  being locked in the lock guard portions  21  of the base block  1 . Thus, when the forward end of the elastic tongue piece  23  is pressed, the return spring  100  is elastically deformed not only in the elastic tongue piece  23  but also over a wide range from the base portion of the elastic tongue piece  23  to the lock portions  24  of the rectangular frame portion  22 . Accordingly, a desired weak elastic force can be obtained in accordance with a predetermined displacement of the return spring  100  even in a narrow space limited within the recess portion  15  of the base block  1 . 
   A part of each guide wall  9  extends to each side surface of the base block  1  as described above. At one side edge, the guide wall  9  sinks in all the area but the central portion and the opposite end portions thereof. At the other side edge, the guide wall  9  sinks at four places between the central portion and the opposite end portions. Then, a shield piece  33  of the ground plate  2  which will be described later is disposed in each sinking position. 
   In the bottom surface of the base block  1 , as shown in  FIG. 3C , the central portion and the outer edge portion thereof is cut off to reach a predetermined depth, and through holes  1   a ,  1   b  and  1   c  are formed to penetrate the centers of the seat portions  20  where the fixed contact portions  7  of the fixed terminals  6  should be placed, respectively. Thus, the fixed terminals  6  can be supported directly by a mold at the time of insert-molding, so that the fixed terminals  6  can be prevented from being displaced. Incidentally, a recess portion  1   d  is provided for a gate used for injection-molding of the base block  1  so that the mark of the gate is prevented from projecting over the bottom surface. 
   As shown in  FIG. 5 , the ground plate  2  is obtained by pressing working out of a conductive plate-like product and rectangular holes  28  are formed respectively on the opposite sides of the ground plate  2 . Contact portions  29  are formed on the opposite sides of each rectangular hole  28  so as to project from the lower surface of the ground plate  2 , respectively. Reinforcing ribs  30  are formed on the opposite side portions of the ground plate  2  so as to bulge upward respectively. Mounting holes  31  are formed near the opposite ends of each reinforcing rib  30 . In addition, foot portions  32  are provided to extend from four places at one side edge of the ground plate  2  and from two places at the other side edge of the ground plate  2 . A wide shield piece  33  is formed in the base portion of each foot portion  32 . 
   In each movable block  3 , as shown in  FIGS. 6A-6C , a support portion  35  made of synthetic resin is integrated with a central portion of a movable contact piece  34  made of a conductive plate material. An escape groove  36  is formed in the central portion of the upper surface of the support portion  35  in the direction in which the movable contact piece  34  extends. A protruding strip  37  is formed in the central portion on each of opposite sides of the escape groove  36 . The escape groove  36  is provided to prevent the mark of a not-shown gate from projecting over the upper surface of the support portion  35 . A pair of protrusion portions  38  are formed in the lower surface of the support portion  35  so that the displacement prevention stopper portion  27  of the return spring  100  is locked. The movable block  3  moves up and down with the support portion  35  being disposed in the rectangular hole  28  of the ground plate  2 . The opposite end portions of the movable contact piece  34  are brought into contact with the contact portions  29  of the ground plate  2  in the upper motion position where the movable block  3  is urged by the return spring  100 . On the other hand, the opposite end portions of the movable contact piece  34  are closed on the fixed contacts  7   a  and  7   c  or  7   b  and  7   c  in the lower motion position. 
   In the electromagnetic block  4 , as shown in  FIGS. 7A and 7B , a coil  41  is wound around an iron core  39  through a spool  40 . The iron core  39  is made from a magnetic plate material bent. The opposite end portions of the iron core  39  are positioned in the retention portions  10  of the base block  1 , and the narrow portions  11  of the retention portions  10  are thermally caulked. Thus, the electromagnetic block  4  is fixed to the base block  1 . The spool  40  is constituted by a chassis portion  42  (see  FIG. 11 ) covering the intermediate portion of the iron core  39 , and guide portions  43   a ,  43   b  and  43   c  formed in the opposite ends and the center of the chassis portion  42  respectively. Each of the guide portions  43   a  and  43   b  in the opposite ends is constituted by a collar portion  44  and a thick portion  45  provided to extend from the collar portion  44 . A groove portion  44   a  is formed in the collar portion  44  so as to serve to guide the coil  41  when the coil  41  is wound by an automatic winding machine. A recess portion  45   a  is formed along the collar portion  44  in the thick portion  45 , and an insulating wall  46  is formed in the vicinity of the recess portion  45   a . A coil terminal  47  is pressed into the thick portion  45 . The recess portion  45   a  serves to reduce the usage of resin and prevent the resin from being deformed after molding, and to chuck the coil  41  when the coil  41  is wound around the chassis portion  42 . The insulating wall  46  insulates adjacent coil terminals  47  from each other (although one coil terminal  47  is pressed into each thick portion  45  in this embodiment, two coil terminals may be pressed into the thick portion  45  in another form, and on such an occasion, insulation of those coil terminals  47  from each other can be secured by the insulating wall  46 ). An escape portion  48  is formed in the end surface of each thick portion  45  so as to secure a space where resin can extend when the narrow portions  11  of the base block  1  are thermally caulked. In addition, one end portion of the iron core  39  is exposed between the opposite inner surfaces of each thick portion  45 , and slopes  45   b  are formed in the upper portions of the opposite inner surfaces of the thick portion  45  so as to be estranged from each other gradually as they go upward. The slopes  45   b  are provided to increase the strength of a molding mold. Further, engagement protrusion portions  49  for engaging with the engagement recess portions  12  of the base block  1  are formed in the lower surfaces of the thick portions  45  respectively. Guide grooves  50  (0.3 mm wide here) extend vertically in the opposite side surfaces of the central guide portion  43   c . An escape recess portion  51  is formed on the upper side of each guide groove  50 , while an adjusting recess portion  52  is formed on the lower side of each guide groove  50 . The recess portions  51  and  52  are provided for making it possible to work a mold for molding the narrow guide grooves  50 . Particularly, the adjusting recess portion  52  also has a function for elastically deforming and adjusting a foot portion  60  of a push-in spring  57  which will be described later. In addition, guide protrusion portions  53  for laying the coil  41  between the pieces of the chassis portion  42  separated by the central guide portion  43   c  are formed at four places in the upper surface of the central guide portion  43   c . Further, a recess portion  43   d  (see  FIG. 11 ) is formed in the lower surface of the central guide portion  43   c , and a permanent magnet  101  is disposed in the recess portion  43   d . The permanent magnet  101  has different polarities in its upper and lower surfaces, and the upper surface thereof is in contact with the iron core  39 . The coil  41  is wound on the coil terminal  47  whose one end portion is pressed into the guide portion  43   a . The coil  41  is inserted into the groove portions  44   a  formed in the collar portions  44  so as to be oriented. After the coil  41  is wound around the chassis portion  42 , the coil  41  is wound around the coil terminal  47  pressed into the guide portion  43   b.    
   A movable iron piece  54  is disposed rotatably under the electromagnetic block  4 . As shown in  FIG. 9A , the movable iron piece  54  is made from a magnetic plate material, and a protruding strip  55  is formed in the central portion of the movable iron piece  54  so as to extend widthwise. The protruding strip  55  is attracted to the lower surface of the permanent magnet  101  so as to allow the movable iron piece  54  to rotate around the protruding strip  55 . In addition, a magnetic shield plate  56  made from a non-magnetic material such as stainless steel is pasted onto the upper surface on one end side of the movable iron piece  54 . Thus, the movable iron piece  54  is off magnetic balance between its opposite end portions as the movable iron piece  54  is rotatably supported on the permanent magnet  101  of the electromagnetic block  4 . Thus, the one end side (opposite to the magnetic shield plate  56 ) of the movable iron piece  54  is attracted to the iron core  39 . 
   The push-in spring  57  is fixed to the central portion of the lower surface of the movable iron piece  54 . As shown in  FIG. 9B , the push-in spring  57  is obtained by press working out of a magnetic plate material. The push-in spring  57  is constituted by a fixed portion  58  fixed to the movable iron piece  54 , a drive portion  59  for driving the movable block  3 , and foot portions  60  supported in the guide grooves  50  of the electromagnetic block  4 . The fixed portion  58  has a rectangular shape to be fixed to the lower surface of the central portion of the movable iron piece  54  by spot welding or the like. The drive portion  59  has a frame-like shape extending from the central portion on each of opposite sides of the fixed portion  58 , formed around the fixed portion  58  and bent downward stepwise. Adjustment portions  61  partially protruding from the movable iron piece  54  are formed on the opposite side portions of the drive portion  59 . A pressure portion  62  for pressing the protruding strip  37  formed in the support portion  35  of the movable block  3  is provided in the central portion at the forward end of each adjustment portion  61 . Each of the foot portions  60  is bent upward from the central portion on either side of the drive portion  59 , so as to be located in the middle between the pressure portions  62 . An arcuate bent portion  63  is formed at the tip of each foot portion  60 . In addition, the foot portions  60  are guided by the guide grooves  50  formed in the central guide portion  43   c  of the electromagnetic block  4 . 
   Incidentally, the push-in spring  57  to be fixed to the movable iron piece  54  may be of a type having no foot portion  60 , as shown in FIG.  8 B. Even such a push-in spring  57  having no foot portion  60  can be also supported easily (see  FIG. 8D ) if a support recess portion  102  is formed as shown in  FIG. 8A  in the adjusting recess portion  52  in the electromagnetic block  4  having the aforementioned configuration. 
   As shown in  FIG. 1 , the casing  5  has a box-like shape whose lower surface is open, and a recess portion  64  for preventing the mark of the gate from projecting is formed in the central portion of the upper surface of the casing  5 . A vent hole  65  is formed in a corner portion of the upper surface of the casing  5 . In addition, in the edge portion of the opening in the lower surface of the casing  5 , standoffs  66  are provided in the central portions of the opposite ends so as to form a predetermined gap between the bottom surface of the base block  1  and a not-shown printed board when the high-frequency relay is mounted on the printed board after the high-frequency relay has been assembled. 
   Next, description will be made on the method for assembling the high-frequency relay. 
   The return springs  100  are disposed in the recess portions  15  of the base block  1  in which the fixed terminals  6  have been insert-molded. Each return spring  100  is disposed to be biased to one side with respect to the fixed contacts  7   a  and  7   c  or  7   b  and  7   c  located in the opposite ends of the return spring  100  in the state where the lock portions  24  are locked in the lock guard portions  21 . That is, an enough distance from the fixed contact portion  7  in the central portion is secured to guarantee the insulation performance. 
   Next, the movable blocks  3  and the ground plate  2  are mounted on the base block  1  sequentially. The projections  17  of the base block  1  inserted into the mounting holes  31  of the ground plate  2  are thermally caulked so that the ground plate  2  is fixed to the base block  1 . In this state, as shown in  FIGS. 10A and 10B , the displacement prevention stopper portion  27  formed in the elastic tongue piece  23  of each return spring  100  is engaged with the protrusion portions  38  of the support portion  35  while the side surfaces of the support portion  35  are guided by the rectangular holes  28  of the ground plate  2 . Thus, each movable block  3  is urged upward in the state where the movable block  3  can be pushed in. As a result, the opposite end portions (movable contacts) of the movable contact piece  34  abut against the contact portions  29  of the ground plate  2 . 
   On the other hand, the coil  41  is wound around the iron core  39  through the spool  40 , and the permanent magnet  101  is disposed in the recess portion  43   d . Thus, the electromagnetic block  4  is formed. Then, the push-in spring  57  is integrated with the central portion of the lower surface of the movable iron piece  54  and the foot portions  60  of the push-in spring  57  are inserted into the guide grooves  50  of the electromagnetic block  4  while the protruding strip  55  of the movable iron piece  54  is attracted to the lower surface of the permanent magnet  101 . Thus, the movable iron piece  54  is disposed rotatably under the electromagnetic block  4 . In this state, the movable iron piece  54  is off magnetic balance due to the magnetic shield plate  56  pasted to one end portion of the movable iron piece  54 . Accordingly, the movable iron piece  54  rotates clockwise in  FIG. 11  in accordance with the attraction of the permanent magnet  101 . 
   Next, the electromagnetic block  4  provided with the movable iron piece  54  and the push-in spring  57  is mounted on the base block  1  mounted with the return springs  100 , the movable blocks  3  and the ground plate  2 . The engagement protrusion portions  49  formed in the guide portions  43   a  and  43   b  of the electromagnetic block  4  respectively are engaged with the engagement recess portions  12  of the base block  1  respectively, and the narrow portions  11  are thermally caulked to retain the iron core  39 . Thus, the electromagnetic block  4  is integrated with the base block  1 . As a result, the switching between the opposite end portions (movable contacts) of the movable contact piece  34  and the fixed contacts  7   a  and  7   c  or  7   b  and  7   c  of the fixed terminals  6  is located within the recess portion  15  surrounded by the ground plate  2 . The shield pieces  33  extending downward are formed at the side edges of the ground plate  2 . In addition, the air layer  16  is formed partially between the ground plate  2  and the protruding strip portion  14  forming the recess portions  15 . Accordingly, the insulation performance in the contact on/off portion is so high that a high-frequency signal can be transmitted suitably. In addition, the sides of the area where the movable block  3  is pressed by the push-in spring  57  due to rotation of the movable iron piece  54  are opened. 
   In this state, a current is once applied to the coil  41  through the coil terminals  47  so as to excite and demagnetize the electromagnetic block  4 . Then, the condition of a signal conducted between the fixed terminals  6   a  and  6   c  or  6   b  and  6   c , that is, the operating characteristic such as the on-off timing of the contacts or the contact pressure is examined. Thus, it can be judged whether the movable iron piece  54  rotates suitably or not. When the operating condition is not suitable, the push-in spring  57  is deformed for adjustment. Here, first, the adjustment portion  61  protruding widthwise relatively to the movable iron piece  54  is grasped directly from its sides, and deformed. When a desired operating condition cannot be obtained by the adjusting work using the adjustment portion  61 , another adjusting work is performed by grasping and deforming the foot portions  60  through the adjusting recess portions  52  formed in the side surfaces of the electromagnetic block  4  to thereby change an angle of the foot portion  60  with respect to the movable block  34 . Thus, desired operating properties can be obtained surely. 
   When the adjusting work is completed thus, the base block  1  is covered with the casing  5 , and the mating face in the bottom surface of the casing  5  is sealed. In the sealing work, seal agent may invade the inside. However, since the seal groove  18  is formed in the base block  1 , there is no fear that the seal agent reaches the drive parts of the movable blocks  3 , the fixed contact portions  7 , or the like. 
   Next, description will be made on the operation of the high-frequency relay. 
   The high-frequency relay formed as described above is in use mounted on a printed board (not-shown) having a ground pattern formed therein. As a result, the contact on-off mechanism can be placed within an area enclosed by the ground plate  2  and the ground pattern of the printed board. Thus, the insulation performance can be enhanced further. 
   The movable iron piece  54  is off magnetic balance due to the magnetic shield plate  56  before a voltage is applied between the coil terminals  47 . Thus, the movable iron piece  54  rotates clockwise around the protruding strip  55  in  FIG. 11  in accordance with the magnetic force of the permanent magnet  101 . Accordingly, one of the movable blocks  3  is pushed down by the pressure portion  62  of the push-in spring  57  so that the opposite end portions (movable contacts) of its movable contact piece  34  are closed on the fixed contacts  7   a  and  7   c  respectively. Thus, continuity is secured between the fixed terminals  6   a  and  6   c . The other movable block  3  is pushed up by the return spring  100  so that the opposite end portions (movable contacts) of its movable contact piece  34  are brought into contact with the contact portions  29  of the ground plate  2  (initial position). 
   Here, when a voltage is applied between the coil terminals  47  so as to excite the electromagnetic block  4 , the movable iron piece  54  is attracted thereto in its end portion distant from the iron core  39 . Thus, the movable iron piece  54  rotates counterclockwise around the protruding strip  55  in FIG.  11 . When the movable iron piece  54  is rotating, the movable iron piece  54  receives only a weak elastic force caused by elastic deformation in the foot portions  60  of the push-in spring  57  fixed to the lower surface of the movable iron piece  54 , particularly in a wide range reaching the bent portions  63  at the tips of the foot portions  60  in contact with the side surfaces forming the guide grooves  50 . Thus, the movable iron piece  54  rotates smoothly. With this rotation, the push-in spring  57  pushes down the movable block  3  against the urging force of the return spring  100 . The push-in spring  57  and the return spring  100  are disposed in substantially symmetrical positions with respect to the contact on-off position so as to cancel components other than vertical components, that is, horizontal components. Thus, most of force acting on the movable block  3  works only vertically. In addition, the return spring  100  elastically deforms not only the elastic tongue piece  23  but also a part of the rectangular frame. Therefore, the return spring  100  is displaced even by push-in force not so strong. Thus, the movable block  3  moves down smoothly so as to close the opposite end portions (movable contacts) of the movable contact piece  34  with the fixed contacts  7   b  and  7   c  respectively, and thereby make continuity between the fixed terminals  6   b  and  6   c . Not only is the upper surface of each fixed contact portion  7  exposed, but the edge portion thereof is also exposed due to the existence of the seat portion  20 . Thus, the contact area with the air increases. As a result, the insulation performance is so high that it is difficult to leak any signal. 
   On the other hand, the movable block  3  released from the push-in force by the rotation of the movable iron piece  54  moves up due to the elastic force of the return spring  100  so as to separate the opposite end portions (movable contacts) of the movable contact piece from the fixed contacts  7   a  and  7   c  respectively, and thereby break the continuity between the fixed terminals  6   a  and  6   c . Then, the opposite end portions of the movable contact piece  34  of the movable block  3  moving up are brought into contact with the contact portions  29  of the ground plate  2  so as to be grounded. Thus, any high-frequency signal is surely prevented from leaking. 
   When the voltage applied between the coil terminals  47  is eliminated, the movable iron piece  54  rotates clockwise in  FIG. 11  in accordance with the elastic force of the push-in spring  57 , the elastic force of the return spring  100 , the magnetic force of the permanent magnet  101  weakened on only one end side of the movable iron piece  54  due to the magnetic shield plate  56 , and the like. Thus, the movable iron piece  54  returns to the initial position. 
   Incidentally, description in this embodiment has been made on a so-called self-reset type relay in which the magnetic shield plate  56  is provided in the movable iron piece  54  so as to change over the contact on-off position between the case where a current is applied to the coil  41  and the case where no current is applied thereto. However, the invention may be configured as follows. That is, the invention may be applied to a so-called self-holding type relay in which the magnetic shield plate  56  is not provided, but the direction in which a current is applied to the coil  41  is changed to thereby change the polarities in the end portions of the iron core  39  so as to change over the contact on-off position. Alternatively, coil terminals  47  may be provided at three places. In this case, one of the coil terminals  47  is used as a common coil terminal, and two coils different in winding direction are provided. The winding direction of a coil connecting the common coil terminal with one of the rest two coil terminals is made different from the winding direction of a coil connecting the common coil terminal with the other. Thus, a current is applied between the common coil terminal and a selected one of the coil terminals so that the movable iron piece  54  can rotate. 
   As is apparent from the above description, according to the invention, a push-in spring provided in a movable iron piece is designed to include foot portions each extending substantially perpendicularly to a movable block wherein an extending direction of the foot portion can be adjusted. Thus, only by deforming each foot portion to thereby change the angle of the foot portion with respect to the movable block, the elastic force acting on the movable iron piece can be adjusted easily so that the rate of occurrence of defective products can be reduced while desired operation properties can be obtained easily.

Technology Category: 5