Abstract:
A technology for making the heat load on an electronic component attached to a target object smaller than before is provided. The electronic component includes a main body, the main body including an electronic component unit adapted to generate an electrical signal and click feeling in accordance with rotation of an engaged portion, a shaft support having a cylindrical portion to be inserted into a through-hole formed in the target object, and a retaining member; and a control shaft made of metal and capable of rotating the engaged portion, the control shaft being inserted into the cylindrical portion after a reflow soldering process of the target object is completed, and being engaged with the engaged portion. The control shaft inserted into the cylindrical portion is retained by the retaining member.

Description:
TECHNICAL FIELD 
     The present invention relates to a rotary operation type electronic component which causes a switch to be opened or closed or causes a resistance value to be varied, by rotation of a control shaft. 
     BACKGROUND ART 
     Conventionally known rotary operation type electronic components include the rotary operation type electronic components disclosed in Japanese Patent Application Laid Open No. 2011-159562 (patent literature 1) and Japanese Patent Application Laid Open No. 2010-218883 (patent literature 2), for example. These rotary operation type electronic components have a control shaft made of metal. 
     To reduce the number of assembly steps, a target object on which the rotary operation type electronic component is mounted, such as a printed circuit board, is often subjected to a reflow soldering process. 
     The reflow soldering process has been conventionally performed on the target object with the rotary operation type electronic component having a metal control shaft attached to it. 
     PRIOR ART LITERATURE 
     Patent Literature 
     
         
         Patent literature 1: Japanese Patent Application Laid Open No. 2011-159562 
         Patent literature 2: Japanese Patent Application Laid Open No. 2010-218883 
       
    
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     However, if the reflow soldering process is performed on the target object after the rotary operation type electronic component having a metal control shaft is attached to the target object, since the metal control shaft absorbs heat, the temperature of the reflow soldering process should be raised. Alternatively, the duration of the reflow soldering process should be extended. However, this would increase the heat load on the electronic component attached to the target object. 
     An object of the present invention is to provide such a rotary operation type electronic component that the heat load on the electronic component attached to the target object becomes smaller than before. 
     Means to Solve the Problems 
     In one aspect of the present invention, a rotary operation type electronic component includes a main body, the main body including an electronic component unit adapted to generate an electrical signal and click feeling in accordance with rotation of an engaged portion, a shaft support having a cylindrical portion to be inserted into a through-hole formed in a target object, and a retaining member; and a control shaft made of metal and capable of rotating the engaged portion, the control shaft being inserted into the cylindrical portion after a reflow soldering process of the target object is completed, and being engaged with the engaged portion. The control shaft inserted into the cylindrical portion is retained by the retaining member. 
     Effects of the Invention 
     The control shaft is attached after the reflow soldering process of the target object is completed. Since the reflow soldering process is performed on the target object while the metal control shaft, which would absorb heat, is not present, the temperature of the reflow soldering can be made lower than before. In addition, the duration of the reflow soldering process can be made shorter than before. Consequently, the heat load on the electronic component attached to the target object can be made smaller than before. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a rotary operation type electronic component; 
         FIG. 2  is an exploded perspective view of another rotary operation type electronic component; 
         FIG. 3A  is a front view of a main body,  FIG. 3B  is a left side view of the main body,  FIG. 3C  is a right side view of the main body,  FIG. 3D  is a plan view of the main body,  FIG. 3E  is a bottom view of the main body, and  FIG. 3F  is a back view of the main body; 
         FIG. 4A  is a front view of another main body,  FIG. 4B  is a left side view of the main body,  FIG. 4C  is a right side view of the main body,  FIG. 4D  is a plan view of the main body,  FIG. 4E  is a bottom view of the main body, and  FIG. 4F  is a back view of the main body; 
         FIG. 5A  is a front view of a shaft support,  FIG. 5B  is a left side view of the shaft support,  FIG. 5C  is a right side view of the shaft support,  FIG. 5D  is a plan view of the shaft support,  FIG. 5E  is a bottom view of the shaft support, and  FIG. 5F  is a back view of the shaft support; 
         FIG. 6A  is a front view of a retaining member,  FIG. 6B  is a left side view of the retaining member,  FIG. 6C  is a right side view of the retaining member,  FIG. 6D  is a plan view of the retaining member,  FIG. 6E  is a bottom view of the retaining member, and  FIG. 6F  is a back view of the retaining member; 
         FIG. 7A  is a front view of another retaining member,  FIG. 7B  is a left side view of the retaining member,  FIG. 7C  is a right side view of the retaining member,  FIG. 7D  is a plan view of the retaining member,  FIG. 7E  is a bottom view of the retaining member, and  FIG. 7F  is a back view of the retaining member; 
         FIG. 8A  is a front view of a rivet,  FIG. 8B  is a left side view of the rivet, and  FIG. 8C  is a right side view of the rivet; 
         FIG. 9A  is a front view of a control shaft,  FIG. 9B  is a left side view of the control shaft,  FIG. 9C  is a right side view of the control shaft, and  FIG. 9D  is a plan view of the control shaft; 
         FIG. 10  is a perspective view showing a state in which the rotary operation type electronic component is attached to a target object; 
         FIG. 11  is a sectional view showing a state in which the control shaft is inserted into the main body; 
         FIG. 12  is a sectional view showing a state in which the control shaft is inserted into the other main body; and 
         FIG. 13  is a sectional view showing the state in which the rotary operation type electronic component is attached to the target object. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Now, an embodiment of a rotary operation type electronic component according to the present invention will be described. 
     The rotary operation type electronic component includes a main body  1  and a control shaft  2 . 
     The main body  1  includes an electronic component unit  11 , a shaft support  12 , a retaining member  13 , and rivets  14 , as shown in  FIG. 1 . The components of the main body  1  will be described next. 
     The electronic component unit  11  has a rectangular parallelepiped shape as shown in  FIG. 3 . Six terminals  11   a  for inputting and outputting an electrical signal are disposed on one of the six faces of the terminal  11 . An engaged portion  11   b  is disposed inside the electronic component unit  11 . The engaged portion  11   b  has two opposite face portions facing each other. 
     The electronic component unit  11  generates an electrical signal and click feeling in accordance with rotation of the engaged portion  11   b . So long as it generates an electrical signal and click feeling in accordance with rotation of the engaged portion  11   b , the electronic component unit  11  can be any type of electronic component and can have any configuration. For example, the electronic component unit  11  may be a switch which turns on or off an electrical signal and may also be a variable resistor which varies its resistance in accordance with the rotation of the engaged portion  11   b . For specific example configurations of the electronic component unit  11 , refer to patent literature 1 and 2. 
     A groove  11   c  shaped to receive the retaining member  13  is formed in a face of the electronic component unit  11  opposite to the shaft support  12 . The retaining member  13  is placed in the groove  11   c . In the example of the electronic component unit  11  shown in  FIG. 3 , the groove  11   c  is bell-shaped. The groove  11   c  has wide portions  11   c   1 , where the retaining member  13  placed in the groove  11   c  can be spread wider when the control shaft  2  is inserted. 
     The electronic component unit  11  has depressed portions  11   d  and through-holes  11   e  at its four corners. 
     The shaft support  12  includes a rectangular plate portion  12   a  and a cylindrical portion  12   b  disposed at a center of the plate portion  12   a , as shown in  FIG. 5 . An external thread  12   b   1  is formed on the outer periphery of the cylindrical portion  12   b . A through-hole is formed inside the cylindrical portion  12   b  and the plate portion  12   a . The plate portion  12   a  has projecting portions  12   a   1  and through-holes  12   a   2  at its four corners. The shaft support  12  is made of resin or metal. 
     The retaining member  13  is a U-shaped spring, as shown in  FIG. 6 . 
     The rivets  14  are stick-shaped as shown in  FIG. 8  and have a flange  14   a  formed at one end. The rivets  14  are made of aluminum, for example. 
     The retaining member  13  is placed in the groove  11   c  of the electronic component unit  11 , and in that state, the projecting portions  12   a   1  of the shaft support  12  are put into the depressed portions  11   d  of the electronic component unit  11 , to connect the shaft support  12  and the electronic component unit  11  together. While the shaft support  12  and the electronic component unit  11  are coupled to each other, the rivets  14  are inserted into the through-holes  11   e  of the electronic component unit  11  and the through-holes  12   a   2  of the shaft support  12 , and the ends of the inserted rivets  14  are caulked. Then, the shaft support  12  and the electronic component unit  11  are integrally secured. 
     The control shaft  2  is bar-shaped and is made of metal. The control shaft  2  has an engaging portion  2   a  at one end and a control portion  2   b  at the other end. The engaging portion  2   a  is shaped to fit the engaged portion  11   b  of the electronic component unit  11 . In the example shown, the engaging portion  2   a  has parallel face portions formed to be 180 degrees apart by cutting two parts off the outer periphery of a column. A slide face portion  2   c  having a smaller diameter than the control portion  2   b  is disposed at a middle of the control shaft  2 . When the control shaft  2  is inserted into the shaft support  12 , the slide face portion  2   c  comes into contact with the inner periphery of the through-hole formed inside the cylindrical portion  12   b . Rotation of the control shaft  2  in that state causes the slide face portion  2   c  to slide on the inner periphery of the through-hole formed inside the cylindrical portion  12   b . Disposed between the slide face portion  2   c  and the engaging portion  2   a  are a groove  2   d  having a smaller diameter than the slide face portion  2   c  and a tapered portion  2   e  whose diameter decreases gradually toward the engaging portion  2   a . The diameter of the largest-diameter portion of the tapered portion  2   e  is larger than the diameter of the groove  2   d.    
     When the rotary operation type electronic component is mounted to a target object  3 , first, just the main body  1  is attached to the target object  3 . In an example illustrated in  FIG. 10  and  FIG. 13 , the main body  1  is attached to the target object  3  by inserting the cylindrical portion  12   b  of the shaft support  12  into a through-hole  3   a  formed in the target object  3  and tightening a nut  4  on the external thread  12   b   1  formed on the outer periphery of the cylindrical portion  12   b . The terminals  11   a  of the electronic component unit  11  are connected to a printed circuit board, not shown, of the target object  3 . In that state, the target object  3  and the main body  1  are both subjected to reflow soldering. 
     The control shaft  2  is then inserted into the cylindrical portion  12   b  of the main body  1 . When the control shaft  2  is inserted into the cylindrical portion  12   b , the tapered portion  2   e  meets the retaining member  13  first. When the control shaft  2  is inserted further, the increasing diameter of the tapered portion  2   e  spreads out the retaining member  13 . The spread retaining member  13  finally returns to its original shape in the groove  2   d  of the control shaft  2  and fits into the groove  2   d . This prevents the control shaft  2  from coming out of the main body  1 . The engaging portion  2   a  of the control shaft  2  engages with the engaged portion  11   b  of the electronic component unit  11 .  FIG. 11  shows a sectional view of a state in which the control shaft  2  is inserted into the main body  1 . In  FIG. 11 , the target object  3  and the nut  4  are omitted. 
     Rotary operation of the control shaft  2  causes the engaging portion  2   a  of the control shaft  2  to rotate the engaged portion  11   b . The electronic component unit  11  generates an electrical signal and click feeling in accordance with the rotation of the engaged portion  11   b.    
     The control shaft  2  is attached after the reflow soldering process of the target object  3  is completed. Since the reflow soldering process of the target object  3  is carried out while the metal control shaft  2 , which would absorb heat, is not present, the temperature of the reflow soldering process can be made lower than before. In addition, the duration of the reflow soldering process can be made shorter than before. Consequently, the heat load on the electronic component attached to the target object  3  can be made smaller than before. 
     Since the control shaft  2  is inserted after the cylindrical portion  12   b  is inserted into the through-hole  3   a  formed in the target object  3 , the diameter of the control portion  2   b  of the control shaft  2  can be larger than the diameter of the through-hole  3   a . In other words, the diameter of the control portion  2   b  of the control shaft  2  can be larger than the diameter of the cylindrical portion  12   b .  FIG. 10  and  FIG. 13  show a rotary operation type electronic component in which the diameter of the control portion  2   b  of the control shaft  2  is larger than the diameter of the through-hole  3   a  or the diameter of the cylindrical portion  12   b.    
     The shape of the retaining member  13  is not limited to the U-shape shown in  FIG. 6 . The retaining member  13  may have a C-shape, which is a ring shape with a gap  13   a , as shown in  FIG. 7 . In that case, the groove  11   c  of the electronic component unit  11  should be circular, as shown in  FIG. 4 .  FIG. 12  shows a sectional view of a state in which the control shaft  2  is inserted into the main body  1  having a C-shaped retaining member  13 . In  FIG. 12 , the target object  3  and the nut  4  are omitted. 
     The groove  11   c  into which the retaining member  13  is fitted is formed in the electronic component unit  11  in the examples shown in  FIG. 3  and  FIG. 4 . However, the groove  11   c  may be formed in the shaft support  12 . Moreover, the retaining member  13  may be disposed in any position of the main body  1 . For example, the position may be inside the main body  1  or may be inside the shaft support  12 . 
     The outer periphery of the cylindrical portion  12   b  does not need to have the external thread  12   b   1 . Such a cylindrical portion  12   b  is just inserted into the through-hole  3   a  of the target object  3  and is not tightened with the nut  4 . 
     The present invention is not limited to the embodiment described above, and changes can be made within the scope of the present invention. 
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
           1  main body 
           11  electronic component unit 
           11   b  engaged portion 
           12  shaft support 
           12   b  cylindrical portion 
           13  retaining member 
           2  control shaft 
           3  target object 
           4  nut