Abstract:
A variable resistance device is provided. Instead of a conventional planar-type structure or a three-dimensional structure using an elastic strip, a variable resistance device with a three-dimensional structure using easy-assembling parts, such as a mount and a spring, is adapted. The easy-assembling parts would not be deformed permanently so that the reliability of the variable resistance device is enhanced.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to a variable resistance device; in particular, the invention relates to a variable resistance device that makes the assembling easier and enhances its quality.  
           [0003]    2. Description of the Related Art  
           [0004]    Variable resistance devices find many uses in electrical equipment. One common use of variable resistance devices is used to control voltage in, for example, flyback transformers.  
           [0005]    When used in a flyback transformer, a variable resistance device must meet a number of requirements. The foremost requirement is size. This poses a problem for variable resistance devices that typically rely on electro-mechanical structures to provide variable resistance.  
           [0006]    Known variable resistance devices also are typically constructed of a relatively large number of small parts, increasing the difficulty of assembly and, correspondingly, the cost of the devices. In addition, the reliability is impaired because of the likelihood that each of the many parts presents an opportunity for failure in the device.  
           [0007]    One example of a known variable resistance device is shown in FIG. 1. Such variable resistance device  10  is consisted of a substrate  11  and a rotor  12 . A resistive region  111  is formed on the substrate  11 . The resistive region  111  is consisted of a central part  1111  and a semi-circular path  1112 . A distance X 1  is maintained as a safe gap between the central part  1111  and the semi-circular path  1112 . The central part  1111  is electrically connected to an external circuit (not shown). A spring  121  is disposed at the bottom of the rotor  12 . The spring  121  has a first end  1211  and a second end  1212 .  
           [0008]    The first end  1211  of the spring  121  is in contact with the central part  1111  of the resistive region  111 . The second end  1212  of the spring  121  is in contact with the semi-circular path  1112  of the resistive region  111 . The second end  1212  is movable along the semi-circular path  1112 .  
           [0009]    Therefore, users can move the second end  1212  along the semi-circular path  1112  by rotating the rotor  12  to change the resistance.  
           [0010]    The disadvantage of the variable resistance device  10  is that its size has a minimum limit. Specifically, since two ends of the spring  121  are on the same plane, in view of the safe gap X 1 , the size of the substrate  11  has a minimum limit.  
           [0011]    The other example of a known variable resistance device  20  is shown in FIG. 2. Such variable resistance device  20  is also consisted of a substrate  21  and a rotor  22 . A resistive region  211  is formed on the substrate  21 . The resistive region  211  comprises a semi-circular path. A point C 1  is used as a center of the semi-circular path. A distance Y 2  is maintained as a safe gap between the point C 1  and the semi-circular path. The rotor  22  is provided with a rod  221  and an elastic strip  222  at its bottom. The elastic strip  222  has a first end  2221  and a second end  2222 . The rod  221  abuts the point C 1  of the substrate  21 . The first end  2221  is movable along the resistive region  211 , and the second end  2222  is electrically connected to an external circuit (not shown) . Therefore, users can move the first end  2221  along the semi-circular path by rotating the rotor  22  to change the resistance.  
           [0012]    As shown in FIG. 2, the first end  2221  of the variable resistance device  20  extends outwardly from the bottom of the rotor  22  in an inclined angle. Hence, comparing with the safe gap X 1  as shown in FIG. 1, the safe gap Y 2  can be reduced. As a result, the size of the substrate  21  can be decreased.  
           [0013]    However, the disadvantages of the variable resistance device  20  are that its elastic strip  222  is easily deformed, it is hard to assemble, and it cannot be assembled repeatedly.  
         SUMMARY OF THE INVENTION  
         [0014]    In view of the disadvantages of the aforementioned conventional variable resistance device, the invention provides a variable resistance device that can make the assembly easier and enhances its quality.  
           [0015]    Accordingly, the variable resistance device of the invention comprises a substrate and a rotor. A resistive region is formed on the substrate. The rotor is disposed on the substrate, after which it is rotatable. The rotor comprises a first contact member, a mount, a rotating member and a second contact member. The first contact member has a first end and a second end, wherein the first end abuts the resistive region in an elastic manner. The mount is used for receiving the first contact member. The rotating member engages the mount. The second contact member, disposed between the mount and the rotating member, abuts the second end of the first contact member in a movable manner.  
           [0016]    Furthermore, the mount has a first through hole and a receiving portion; therefore, the rotating member passes through the first through hole to engage the mount, and the receiving portion is used for receiving the first contact member.  
           [0017]    Furthermore, the receiving portion is a second through hole.  
           [0018]    Furthermore, the first contact member comprises a rivet, a spring and a ball. The rivet abuts the resistive region. The spring, surrounding the rivet, is disposed inside the second through hole and abutting the rivet in one end. The ball abuts the second contact member and the other end of the spring.  
           [0019]    Furthermore, the first contact member comprises a spring, a first ball and a second ball. The spring is disposed inside the second through hole. The first ball is disposed between the second contact member and one end of the spring. The second ball is disposed between the substrate and the other end of the spring.  
           [0020]    Furthermore, the first contact member comprises a rivet and a spring. The rivet abuts the resistive region in one end. The spring, surrounding the rivet, is disposed inside the second through hole.  
           [0021]    Furthermore, the second contact member has a hollow portion for the rotating member passing through.  
           [0022]    Furthermore, the variable resistance device further comprises a housing. The housing has a first portion for combining with the substrate and a second portion for combining with the rotor.  
           [0023]    Furthermore, a variable resistance device of the invention comprises a substrate and a rotor. A resistive region is formed on the substrate. The rotor is rotatablly disposed on the substrate and comprises a first contact member, a mount, a rotating member, a second contact member and a cushion member. The first contact member has a first end and a second end. The first end abuts the resistive region. The mount is used for receiving the first contact member. The rotating member engages the mount. The second contact member, disposed between the mount and the rotating member, abuts the second end of the first contact member in a movable manner. The cushion member, disposed between the second contact member and the rotating member, is used for cushioning the contact between the first contact member and the resistive region.  
           [0024]    Furthermore, a variable resistance device of the invention comprises a substrate and a rotor. A resistive region is formed on the substrate. The rotor is disposed on the substrate, after which it can rotate, and comprises a first contact member, a mount, a rotating member and a conducting interface. The first contact member has a first end and a second end. The first end abuts the resistive region. The mount is used for receiving the first contact member. The rotating member engages the mount, and the rotating member abuts the mount. The conducting interface is formed on a surface, abuts the mount, of the rotating member. The conducting interface abuts the second end of the first contact member in a movable manner. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    The invention is hereinafter described in detail by reference to the accompanying drawings in which:  
         [0026]    [0026]FIG. 1 is a schematic view depicting a conventional variable resistance device;  
         [0027]    [0027]FIG. 2 is a schematic view depicting the other conventional variable resistance device;  
         [0028]    [0028]FIG. 3 a  is a deposition diagram depicting a first embodiment of a variable resistance device of the invention;  
         [0029]    [0029]FIG. 3 b  is a side view depicting the first embodiment of the variable resistance device of the invention, wherein the assembling of the variable resistance device is completed;  
         [0030]    [0030]FIG. 4 a  is a schematic view depicting the first embodiment of the variable resistance device of the invention;  
         [0031]    [0031]FIG. 4 b  is a diagram showing a distance between a protrusion and a rivet of the first embodiment of the variable resistance device of the invention;  
         [0032]    [0032]FIG. 5 is a deposition diagram depicting a second embodiment of a variable resistance device of the invention;  
         [0033]    [0033]FIG. 6 is a deposition diagram depicting a third embodiment of a variable resistance device of the invention;  
         [0034]    [0034]FIG. 7 is a deposition diagram depicting a fourth embodiment of a variable resistance device of the invention;  
         [0035]    [0035]FIG. 8 a  is a deposition diagram depicting a fifth embodiment of a variable resistance device of the invention;  
         [0036]    [0036]FIG. 8 b  is a schematic diagram depicting the other mount of the invention; and  
         [0037]    [0037]FIG. 9 is a deposition diagram depicting a sixth embodiment of a variable resistance device of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
     First Embodiment  
       [0038]    As shown in FIGS. 3 a,    3   b,    4   a  and  4   b,  a variable resistance device  30  of a first embodiment of the invention comprises a substrate  31  and a rotor  32 . A resistive region  311  is formed on a surface, facing the rotor  32 , of the substrate  31 .  
         [0039]    The rotor  32  is disposed on the substrate  31 , after which it is rotatable. The rotor  32  comprises a rotating member  321 , a second contact member  322 , a mount  323  and a first contact member  324 .  
         [0040]    The first contact member  324  abuts the resistive region  311  in an elastic manner. In this embodiment, the first contact member  324  comprises a spring  3241  and a rivet  3242 . The spring  3241  provides the first contact member  324  with an elastic force. One end of the rivet  3242 , hereinafter also called a first end of the first contact member  324 , abuts the resistive region  311 . In view of protecting the substrate&#39;s life, it is preferable that the first end be ball-shaped.  
         [0041]    The mount  323  is provided with a first through hole  3231  and a receiving portion  3232 , hereinafter also called a second through hole. The first through hole  3231  is used for the rotating member  321  passing through. The second through hole  3232  is used for receiving the first contact member  324 . The spring  3241 , surrounding the rivet  3242 , is disposed inside the second through hole  3232 .  
         [0042]    The rotating member  321  is provided with a rod  3211  that passes through the first through hole  3231  and engages with the mount  323 . By the engagement between the rod  3211  and the first through hole  3231 , the rotating member  321  can rotate the mount  323 . The rod  3211  abuts the substrate  31 . The second contact member  321 , disposed between the rotating member  321  and the mount  323 , is independent from the rotation of the rotating member  321  and the mount  323 . The other end of the rivet  3242 , hereinafter also called a second end of the first contact member  324 , abuts the second contact member  322 . The second contact member  322  is provided with a hollow portion  3221  and a protrusion  3222 . The hollow portion  3221  is used for the rod  3211  passing through. The protrusion  3222  is electrically connected to an external circuit (not shown).  
         [0043]    In addition, the variable resistance device  30  comprises a housing  33 . The housing  33  has a first portion  331  for combining with the substrate  31  and a second portion  332  for combining with the rotor  32 .  
         [0044]    It is noted that the housing  33  is omitted in FIG. 3 b  and FIG. 4 a.  After the assembling of the variable resistance device  30  is completed, as shown in FIG. 3 b,  users can move the rivet  3242  along the resistive region  311  by rotating the rotating member  321 . As a result, users can attain a desired value of the resistance.  
         [0045]    [0045]FIG. 4 b  shows a distance X 3  between the protrusion  3222  and a contact point that is between the rivet  3242  and the resistive region  311 . Since the distance X 3  is perpendicular, a distance Y 3  between a semi-circular path and its center C 2  can be reduced. Hence, the size of the substrate  31  is decreased correspondingly.  
         [0046]    Furthermore, the first contact member of this embodiment is consisted of durable parts, such as the spring and the rivet; therefore, the assembly is easier. In addition, the assembling flexibility of this variable resistance device is enhanced. As a result, the yield of the variable resistance device is increased.  
       Second Embodiment  
       [0047]    A second embodiment of a variable device  40  of the invention is shown in FIG. 5. Some parts of the variable resistance device  40  are the same as the first embodiment; therefore, their descriptions are omitted.  
         [0048]    The difference between this embodiment and the first embodiment is that in the second embodiment, the first contact member  424  comprises a ball  4241 , a spring  4242  and a rivet  4243 . The ball  4241  is additionally disposed between the spring  4242  and the second contact member  422 . Since the ball  4241  is disposed on the end, facing the second contact member  422 , of the spring  4242 , the movement of the first contact member  424  on the second contact member  422  becomes smoother.  
       Third Embodiment  
       [0049]    A third embodiment of a variable device  50  of the invention is shown in FIG. 6. Some parts of the variable resistance device  50  are the same as the second embodiment; therefore, their descriptions are omitted.  
         [0050]    The difference between this embodiment and the second embodiment is that in the third embodiment, the first contact member  524  comprises a first ball  5241 , a spring  5242  and a second ball  5243 . The second ball  5243  is additionally disposed between the spring  5242  and the substrate  51  to replace the rivet in the second embodiment. Since the second ball  5243  is disposed on the end, facing the substrate  51 , of the spring  5242 , the movement of the first contact member  524  on the substrate  51  becomes smoother.  
       Fourth Embodiment  
       [0051]    A fourth embodiment of a variable device  60  of the invention is shown in FIG. 7. Some parts of the variable resistance device  60  are the same as the first embodiment; therefore, their descriptions are omitted.  
         [0052]    The difference between this embodiment and the first embodiment is that in the fourth embodiment, the cushion member  625  is additionally disposed between the second contact member  622  and the rotating member  621 . Apparently, the cushion member  625  has a cushion function, and it is used to replace the spring of the above embodiments. Therefore, the first contact member  624  can be made by a stick.  
       Fifth Embodiment  
       [0053]    A fifth embodiment of a variable device  70  of the invention is shown in FIG. 8 a  and FIG. 8 b.  Some parts of the variable resistance device  70  are the same as the first embodiment; therefore, their descriptions are omitted.  
         [0054]    The difference between this embodiment and the first embodiment is that in the fifth embodiment, the first contact member  724  comprises a spring portion  7241  and two contact portions  7242 , integrally formed at both ends of the spring portion  7241 . Ball-shaped dots  72421  are formed on the surface of the contact portions respectively; therefore, the contact between the second contact member  722  and the substrate  71  becomes smooth.  
         [0055]    Also, the receiving portion  7232  can be formed as shown in FIG. 8 b  to fit with the shape of the first contact member  724 . The first contact member  724  is putted into the mount  723  in an arrow direction of FIG. 8 b.  After the first contact member  724  is disposed inside the mount  723 , the spring portion  7241  is blocked by a plate  72321  and the contact portions  7242  are located inside cuts  72322  respectively.  
       Sixth Embodiment  
       [0056]    A sixth embodiment of a variable device  80  of the invention is shown in FIG. 9. Some parts of the variable resistance device  80  are the same as the first embodiment; therefore, their descriptions are omitted.  
         [0057]    The difference between this embodiment and the first embodiment is that in the sixth embodiment, a conducting interface  8212  is formed on a surface, abutting the mount  823 , of the rotating member  821 ; therefore, the second contact member of the first embodiment is omitted. The rotating member  821  directly engages with the mount  823 . One end of the first contact member  824  abuts the conducting interface  8212  in a movable manner.  
         [0058]    Electric-conductive material of the conducting interface  8212  is formed on the rotating member  821  by the electroplating. As a result, since the second contact member is omitted, the assembling of the variable resistance device  80  becomes easier.  
         [0059]    As stated above, since the variable resistance device of this invention is a three-dimensional structure, its yield can be increased. In addition, since the parts of this variable resistance device can not be deformed easily, its reliability is enhanced.  
         [0060]    While the invention has been particularly shown and described with reference to a preferred embodiment, it will be readily appreciated by those of ordinary skill in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. It is intended that the claims be interpreted to cover the disclosed embodiment, those alternatives which have been discussed above, and all equivalents thereto.