Patent Publication Number: US-7211759-B2

Title: Switch coupling structure

Description:
FIELD OF THE INVENTION 
   The present invention relates to a switch coupling structure and particularly to a switch coupling structure which includes a cap and a seat that have mating fastening portions formed in a convex and concave fashion on a coupling surface to facilitate a secured coupling. 
   BACKGROUND OF THE INVENTION 
   The conventional switch case generally includes a cap and a seat that are coupled through tenons and mortises as shown in  FIG. 1  to form a housing chamber inside to hold switch elements. Such a structure has drawbacks, notably: 1. The tenons and mortises have tolerances which make coupling of the cap and seat not precise and firm, and loose coupling occurs; 2. As the cap and seat have tolerances on the coupling surface, moisture tends to enter the switch and results in damage of the conductive elements in the switch; 3. Expensive molds have to be made to produce the mating tenons and mortises, hence the cost is higher. 
     FIG. 2  illustrates another conventional switch. It has a cap and a seat fastened through a bonding material on the coupling surface. Such a structure can prevent the moisture from entering the switch so that the conductive elements are less likely to be damaged. The production cost also is lower. However, to evenly dispense the bonding material on the bonding surface is difficult, and the bonding material easily overflows from the flat bonding surface under pressure during fastening process to smear the interior or exterior of the switch. The switch elements could be tampered and malfunction or result in poor contact. The production yield could suffer and the production cost could increase. 
   R.O.C. patent publication No. 484748 discloses a waterproof switch which includes a hollow base with an open end and a pushbutton located on the open end. The inner wall of the base at the open end has at least one jutting detent wall, and the inner walls of the detent wall and the base are interposed by a trough. The trough has at least one channeling port directing outwards to discharge unwanted liquid and external material. It is waterproof and can prevent liquid and external material from entering the switch. But the air contains moisture which still can seep into the switch. Hence how to develop a switch with a case which can be coupled firmly to fend off moisture and reduce damage of the conductive elements in the switch is an issue remained to be resolved in the industry. 
   Other references of switch with the seat and cap coupled through latches can be found in R.O.C. patent publication Nos. 531036, 515561 and 458358. 
   SUMMARY OF THE INVENTION 
   The primary object of the present invention is to solve the aforesaid disadvantages. The invention provides a switch which includes a cap and a seat that are coupled to form a housing chamber to hold switch elements. The cap and seat include a first fastening portion and a second fastening portion that are formed in a mating convex and concave fashion on a coupling surface. The first and second fastening portions are partly or entirely covered by a bonding material to bond the cap and seat and form a sealed switch. 
   Another object of the invention is to provide a switch that has the cap and seat bonded by the bonding material without overflowing outside the first and second fastening portions. The first and second fastening portions on the coupling surface have an equal coupling area, or the concave fastening portion is larger than the convex fastening portion. And the second fastening portion has a depth greater than the length of the first fastening portion. Hence when the first and second fastening portions are coupled on the coupling surface, an additional space is formed between the first and second fastening portions to contain the extra bonding material and prevent the bonding material from overflowing. 
   Yet another object of the invention is to provide a waterproof switch. Through the first and second fastening portions that have mating convex and concave fastening portions, moisture is less likely to enter the switch. Moreover, the interior of the switch is sealed because of the two fastening portions are bonded by the bonding material, moisture cannot enter the switch. 
   Another object of the invention is to increase the bonding area of the cap and seat to enhance the bonding effect. With the first and second fastening portions formed in a mating convex and concave fashion, the contact surface is larger. Hence the surface covered by the bonding material also is greater. As a result, the bonding effect is enhanced. 
   The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded view of a conventional switch. 
       FIG. 2  is a side view of another conventional switch partly cut away. 
       FIG. 3  is an exploded view of the present invention. 
       FIG. 4A  is a sectional view of the present invention. 
       FIG. 4B  is a fragmentary enlarged view of the present invention. 
       FIG. 5  is a schematic view of an embodiment of the invention. 
       FIG. 6  is a schematic view of another embodiment of the invention. 
       FIGS. 7A through 7H  are schematic views of various other embodiments of the present invention. 
       FIG. 8  is a schematic view of yet another embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Please referring to  FIGS. 3 ,  4 A and  4 B, the switch  1  according to the invention includes a cap  10  and a seat  20  that are coupled together to form a housing chamber  40  inside to hold switch elements  50 . The seat  20  and cap  10  form a coupling surface after fastened. The cap  10  and seat  20  have respectively a first fastening portion  11  and a second fastening portion  21  that are formed in a convex and concave fashion to mate each other for coupling. Either the first fastening portion  11  or second fastening portion  21  is covered by a bonding material  30 , or both the fastening portions  11  and  21  are covered by the bonding material  30  as shown in  FIG. 4B . After the first fastening portion  11  of the cap  10  (referring to the drawings, the first fastening portion  11  is extended from the cap  10 . However this is not the limitation. It can also be extended from the seat  20 ) is covered by the bonding material  30 , it can be coupled with the second fastening portion  21  of the seat  20  (the bonding material  30  may also be dispensed on the second fastening portion  21  rather than on the first fastening portion  11 ) to enable the cap  10  and the seat  20  to be fastened to become the switch  1 . By bonding the first fastening portion  11  and the second fastening portion  21  through the bonding material  30 , the switch  1  is sealed tightly. Hence the moisture in the air does not seep into the switch  1  through the coupling surface of the cap  10  and the seat  20 . The switch elements inside the switch  1  can be protected without damaging. 
   Refer to  FIGS. 5 ,  7 A,  7 B and  7 H for various embodiments of the invention. The first fastening portion  11  and the second fastening portion  21  have the same area on the coupling surface. But the depth of the second fastening portion  21  is greater than or equal to the length of the first fastening portion  11 . Hence when the two fastening portions are coupled and fastened, an additional overflow space is formed to hold the extra bonding material  30 . It is to be noted that the first fastening portion  11  and the second fastening portion  21  are formed in desired profiles to create an overflow space to hold extra bonding material  30 . Hence the extra bonding material  30  does not overflow inside and outside the switch  1 , and does not smear and affect the switch elements inside and outside. 
   Refer to  FIG. 6  for an embodiment of the invention. The indented second fastening portion  21  has a transverse trough  211  (The trough may also be formed other than transverse). Hence the bonding material  30  can be stored before coupling of the two fastening portions  11  and  21 . During installation, the convex first fastening portion  11  squeezes the bonding material  30  held in the second fastening portion  21  so that the bonding material  30  is diffused to fill the space formed between the first and second fastening portions  11  and  21 , and spreads to cover the surfaces of the first and second fastening portions  11  and  21 . Thus by dispensing the bonding material  30  in advance into the second fastening portion  21 , the diffusion range the bonding material  30  can be controlled without overflowing outside or inside the switch  1 . 
   Refer to  FIGS. 7C through 7G  for other embodiments of the invention. The first fastening portion  11  and the second fastening portion  21  are located on the coupling surface but have different areas (however can be coupled together). The length of the second fastening portion  21  is greater than the first fastening portion  11  so that an overflow space is formed to hold the extra bonding material  30  when they are coupled together. The size of the convex fastening portion is smaller than the concave fastening portion, hence a larger overflow space can be formed for the bonding material  30 . Therefore the extra bonding material  30  can be held in the overflow space without overflowing outside and inside the switch  1 . 
   In summary, the main features of the invention include: the cap  10  and seat  20  are coupled to form a housing chamber  40  inside; the cap  10  and the seat  20  have respectively a first fastening portion  11  and a second fastening portion  21  that are formed in a convex and concave fashion mating each other to form coupling; either or both the first and second fastening portions  11  and  21  are covered by a bonding material  30 ; and the concave fastening portion may have a trough  211  on the bottom to store the bonding material  30 . The invention aims to prevent the bonding material  30  from overflowing inside and outside the switch  1  so that other elements are not smeared or affected. The convex and concave profiles of the fastening portions can increase the bonding area of the cap  10  and seat  20  to enhance the bonding effect. Moreover, the coupling surface which entirely surrounds the first and second fastening portions  11  and  21  can seal the switch  1  to prevent the moisture from seeping into the switch  1  through the coupling surface. The convex and concave fastening portions may be formed in various profiles as shown in  FIGS. 4B ,  5 ,  7 A through  7 H. The cross section of the convex fastening portion also may have many different choices. The concave fastening portion is formed in a profile mating the cross section of the convex fastening portion. As shown in  FIG. 6 , the concave fastening portion may have a trough  211  to prevent overflow of extra bonding material  30 . In addition, coupling of the cap  10  and seat  20  is not limited to covering the entire periphery. As shown in  FIG. 8 , the fastening portions  11  and  21  may also be formed in sections and spaced from each other to achieve the bonding effect for the cap  10  and seat  20 . All the features previously discussed are adaptable to coupling and fastening of switches. The switches thus formed have significant advantages over the conventional switches. 
   While the preferred embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.