Abstract:
The conventional variable resistor has a problem in that, because a pressure-sensitive member made of a pressure-sensitive conductive rubber is used, a serious scattering is caused in the characteristic (change curve), and scattering of thickness in the manufacture of the pressure-sensitive member results in a large scatter of the characteristic (change curve). The variable resistor of the invention uses the first resistor pattern forming the variable resistor. It is therefore possible to provide a variable resistor which scattering in the manufacture is smaller, can achieve a uniform resistance change characteristic, and gives a high accuracy.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a variable resistor adapted to be used for a video game machine or the like. 
     2. Description of the Related Art 
     A conventional variable resistor will be described with reference to FIGS. 10 to  13 . An insulated substrate  32  is housed in a case  31  comprising a synthetic resin form. 
     A fixed contact  33  having a pair of comb-shaped contacts formed at a certain interval on one side surface of the insulated substrate  32  as shown in FIGS. 11 and 13. 
     A fixed resistor  34  is attached to the other surface of the insulated substrate. As shown in FIG. 13, connection of the fixed contact  33  and the fixed resistor  34  is accomplished by connecting one of the contacts of the fixed contact  33  and a side of the fixed resistor with a connection line  35 . The other contact of the fixed contact  33  is grounded with a connection line  36 . The other end of the fixed resistor  34  is connected to a power supply terminal T 1  via a connection line  37 . An outgoing terminal T 2  is connected to the connection line  35  via a connection line  38 . 
     A pressure-sensitive member  39  is made of a disk-shaped pressure-sensitive conductive rubber. This pressure-sensitive member  39  is arranged to be spread over the pair of fixed contacts  33 . 
     A buffer member  40  is made of a rubber material. The buffer member  40  is placed on the upper surface of the pressure-sensitive member  39  in a state in which it faces the fixed contact  33 , and attached thereto by an adhesive or the like. 
     An operating member  41  comprising a synthetic resin form or the like is positioned on the upper surface of the buffer member  40  and attached in a state projecting from a hole  31   a  of the case  31 . 
     Operation of the conventional variable resistor having the aforementioned configuration will now be described. When pressing the upper surface of the operating member  41 , the pressure-sensitive member  39  is pressed via the buffer member  40  and deformed under the pressure to cause a change in resistance value at the portion of the pressure-sensitive member  39  thus pressed. The change in resistance value caused by a change in this pressing force is detected between the pair of comb-shaped contacts of the fixed contact  33 . 
     Upon release of the pressing operation of the operating member  41 , the pressure-sensitive member  39  and the buffer member  40  recover the original state thereof under the effect of their own elasticity, and at the same time, the operating member  41  as well recovers its original state. 
     The change characteristic of pressing force and electric resistance when using the pressure-sensitive member  39  is such that, as shown in FIG. 12, the resistance value steeply changes in the initial stage of pressing, exhibits a curved change in the middle stage that follows, and almost no change in the final stage, as represented by a change curve K 2 . 
     Because the pressure-sensitive member  39  is made of a pressure-sensitive conductive rubber, the characteristic (change curve) shows a large scattering, and in the manufacture of the pressure-sensitive member  39 , furthermore, a scatter occurs in thickness, resulting in a serious scattering of characteristic (change curve). 
     Such a variable resistor is adapted to be used in an electric circuit diagram as shown in FIG. 13, incorporated in a game machine or the like. 
     In this circuit diagram, when a voltage is impressed between a terminal T 1  and the connection line  36 , an output voltage available between the fixed resistor  34  and the variable resistor based on the pressure-sensitive member  39  on the fixed contact  33  is taken out from a terminal T 2 . 
     When using such a variable resistor, for example, for speed operation of vehicle in a game machine, the resistance value steeply changes in the initial stage of pressing operation of the operating member  41 , thus making it difficult to perform speed operation. In the latter stage of pressing operation, there is almost no change in resistance value. This causes the operator to feel an uncomfortable sense of being out of tune with the speed relative to the pressing operation. 
     When utilizing only the curved changing portion in the middle of the change curve K 2 , the slight change in resistance value during this course leads to a poorer operability. 
     In the conventional variable resistor, the use of the pressure-sensitive member  39  made of a pressure-sensitive conductive rubber causes a serious scattering of characteristic (change curve). Further, in the manufacture of the pressure-sensitive member  39 , scattering of thickness poses a problem of a large scattering of the characteristic (change curve). 
     When using the variable resistor using a pressure-sensitive member  39 , for example, for speed operation of a vehicle in a game machine, a steep change in resistance value in the initial stage of pressing operation of the operating member  41  makes it difficult to perform speed operation, and in the latter stage of pressing operation, the slightest change in resistance value causes a problem of a serious feeling of uncomfortability of being out of tune with the speed relative to the pressing operation. 
     When using only the curved changing portion in the middle of the change curve K 2  of the pressure-sensitive member  39 , the slightest change in resistance value in this middle stage leads to a problem of a poorer operability. 
     In this case, the pressure-sensitive member  39  is always in a state of preliminarily being pressed by the fixed contact  33 . The pressure in this case is not constant under the effect of dispersion of size of parts and assembly, thus resulting in a serious scatter of output derived from the outgoing terminal T 2  in the non-operating state. In addition, deterioration with time of elasticity of the pressure-sensitive member  39  leads to a problem of a shorter service life. Since it is necessary to use the fixed resistor  34  separately from the variable resistor and the fixed resistor  34  is attached and wired onto the insulated substrate  32 , there is posed another problem of complicated operation and a higher cost. 
     SUMMARY OF THE. INVENTION 
     As first means for solving the aforementioned problems, there is provided a configuration in which a variable resistor comprises an insulated substrate; first and second resistor patterns formed on the insulated substrate; a first conductor pattern electrically connecting ends on one side of the first and second resistor patterns; a deformable conductive contact, having a convex curved surface toward the insulated substrate, and arranged opposite to the first resistor pattern; and a holding member having the conductive contact provided thereon; wherein the conductive contact is caused to deform to change the contact area so as to agree with the first resistor pattern so that the resistance value is variable. 
     Second solving means is a configuration in which second and third conductor patterns are formed in electrical communication with the other ends of the first and second resistor patterns; and the first resistor pattern positioned between the first and second conductor patterns has a resistance value larger than the resistance value of the second resistor pattern positioned between the first and third conductor patterns. 
     Third solving means is a configuration in which the first conductor pattern has a belt-shaped portion; a resistive element is formed by printing so as to extend in two opposite directions across the belt-shaped portion; the first resistor pattern is composed of the resistive element extending in one of the directions, and the second resistor pattern is composed of the resistive element extending in the other direction. 
     Fourth solving means is a configuration in which the upper surface of the second resistor pattern is covered with an insulating layer. 
     Fifth solving means is a configuration in which the conductive contact has a width larger than the width of the first resistor pattern formed into a rectangular shape so that the conductive contact is in contact with the whole width of the rectangle of the first resistor pattern. 
     Sixth solving means is a configuration in which the conductive contact is made by mixing a rubber material with carbon. 
     Seventh solving means is a configuration in which the holding member has legs formed so as to be in contact with the insulated substrate and surround the conductive contact; and the legs have an opening in a direction of the curved surface. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial sectional view of the variable resistor of the present invention; 
     FIG. 2 is a plan view of an insulated substrate in the variable resistor of the invention; 
     FIG. 3 is a sectional view of FIG. 2 cut along the line III—III; 
     FIG. 4 is a bottom view of a holding member in the variable resistor of the invention; 
     FIG. 5 is a sectional view of FIG. 4 cut along the line V—V; 
     FIG. 6 is a sectional view of FIG. 4 cut along the line VI—VI; 
     FIG. 7 is a descriptive view illustrating the relationship between the conductive contact and the resistor pattern in the variable resistor of the invention; 
     FIG. 8 is a graph illustrating the change characteristic of pressing force and electric resistance in the variable resistor of the invention; 
     FIG. 9 is a circuit diagram of the variable resistor of the invention; 
     FIG. 10 is a partial sectional view of a conventional variable resistor; 
     FIG. 11 is a descriptive view illustrating the relationship between the fixed contact and the buffer member of the pressure-sensitive member in the conventional variable resistor; 
     FIG. 12 is a graph illustrating the change characteristic of pressing force and electric resistance in the conventional variable resistor; and 
     FIG. 13 is a wiring diagram of the conventional variable resistor. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The variable resistor of the present invention will now be described with reference to FIGS. 1 to  9 . FIG. 1 is a partial sectional view of the variable resistor of the present invention; FIG. 2 is a plan view of an insulated substrate in the variable resistor of the invention; FIG. 3 is a sectional view of FIG. 2 cut along the line III—III; FIG. 4 is a bottom view of a holding member in the variable resistor of the invention; FIG. 5 is a sectional view of FIG. 4 cut along the line V—V; FIG. 6 is a sectional view of FIG. 4 cut along the line VI—VI; FIG. 7 is a descriptive view illustrating the relationship between the conductive contact and the resistor pattern in the variable resistor of the invention; FIG. 8 is a graph illustrating the change characteristic of pressing force and electric resistance in the variable resistor of the invention; and FIG. 9 is a circuit diagram of the variable resistor of the invention. 
     The variable resistor of the invention will now be described with reference to FIGS. 1 to  9 . A case  1  comprising a synthetic resin form or the like has a hole  1   a . A rectangular substrate  2  serving as a supporting substrate comprises a hard insulated substrate or the like, and in a state in which it is housed in the case  1 , is attached to the case  1  by appropriate means. 
     The rectangular insulated substrate  3  comprises a flexible insulating material. A first resistor pattern  4  for the rectangular variable resistor and a second resistor pattern  5  for a rectangular fixed resistor are arranged in parallel with each other on the upper surface of the insulated substrate  3  as shown in FIG.  2 . 
     A first conductor pattern  6  having a belt-shaped portion  6   a  is formed below the boundary between the first and second resistor patterns  4  and  5  on the upper surface of the insulated substrate  3 . The belt-shaped portion  6   a  connects the ends of the first and second resistor patterns  4  and  5 . A second conductor pattern  7 , positioned below the other end of the first resistor pattern  4 , electrically communicates with the first resistor pattern  4 , and a third conductor pattern  8 , positioned below the other end of the second resistor pattern  5 , electrically communicates with the second resistor pattern  4 . These conductor patterns  7  and  8  are formed on the upper surface of the insulated substrate  3 . 
     In this connecting configuration, circuits are arranged as shown in FIG.  9 . The first conductor pattern  6  takes the form of a pattern for taking out an output voltage (OUTPUT) available between the first and second resistor patterns  4  and  5  when a voltage is impressed between the third conductive pattern  8  for grounding (GND) and the second conductor pattern  7  for power supply (VCC). 
     The insulating layer  9  comprising an insulating material is formed on the upper surface of the insulated substrate  3  so as to cover the entire surface of the second resistor pattern  5  for fixed resistance and portions of the first and third conductor patterns  6  and  8 . 
     The method for forming these first and second resistor patterns  4  and  5 , the first, second and third conductor patterns  6 ,  7  and  8 , and the insulating layer  9  comprises the following steps. First, the first, second and third conductor patterns  6 ,  7  and  8  comprising a silver paste are simultaneously formed by printing on the insulated substrate  3 . 
     Then, the first and second resistor patterns  4  and  5  are simultaneously formed by printing a carbon resistor paste into rectangular shapes over the first, second and third conductor patterns  6 ,  7  and  8 , extending across the belt-shaped portion  6   a  of the first conductive pattern  6  in two opposite directions. 
     Finally, the insulating layer  9  is formed by printing an insulating paste comprising an insulating material so as to cover the second resistor pattern  5 , thus completing the manufacture. 
     The insulated substrate  3  having the aforementioned configuration is attached to the upper surface of the substrate  2  by appropriate means including sticking with an adhesive. 
     The holding member  10  comprising a form of an elastic material such as rubber is in a dome shape as shown in FIGS. 4 to  6 , and has a holding portion  10   a  serving as a ceiling plate, a dome-shaped leg  10   b  extending downward from the holding portion  10   a , and a notch-shaped opening  10   c  provided on the leg  10   b  face to face. 
     The arcuate conductive contacts  11  are formed by mixing carbon with a rubber material. These conductive contacts  11  are attached to the lower part of the holding portion  10   a  while being surrounded by the leg  10   b  of the holding member  10 . 
     These conductive contacts  11  are formed integrally with the holding member  10  by forming simultaneously with forming of the holding member  10 . Each of these conductive contacts has a curved surface  11   a  convex downward as shown in FIGS. 1,  5  and  7 , and this curved surface  11   a  is formed with the center portion at the lowest position. 
     The holding member  10  having the conductive contacts  11  attached thereto, with the first resistor pattern  4  surrounded by the leg  10   b , is placed with the lower part of the leg  10   b  in contact with the insulated substrate  3 . 
     At this point, the arcuate conductive contacts  11  has the convex curved surface  11   a  arranged opposite to the insulated substrate  3  so as to cover the first rectangular resistor pattern  4  and to face the first resistor pattern  4 . 
     When pressing the upper part of the holding portion  10   a  facing the first resistor pattern  4  in this state, the leg  10   b  is elastically deformed. The curved surface  11   a  of the conductive contact  11  comes into contact with the center portion of the first resistor pattern  4 . When the holding portion  10   a  is further pressed, the curved surface  11   a  deforms, and the contact area with the first resistor pattern  4  increases gradually, thus leading to a smaller resistance value at the both ends of the first resistor pattern  4 , and imparting the functions as a variable resistor. 
     When pressing of the holding portion  10   a  is released, the holding portion  10   a  recovers the original state thereof under the effect of elasticity of the legs  11   b , and in the meantime, the contact area of the curved surface  11   a  with the first resistor pattern  4  gradually decreases while changing the resistance value. The curved surface  11   a  thus recovers the original state thereof. 
     More specifically, by pressing the holding portion  10   a , the conductive contacts  11  deform in a resistance changing face direction Z which is the direction changing the contact area of the first resistor pattern  4 , increasing or reducing the contact area so as to make the resistance value variable. 
     Upon this deformation of the conductive contacts  11 , the presence of the insulating layer  9  prevents contact with the second resistor pattern  5  which is a fixed resistor. 
     The width H 1  of the conductive contact  11  is larger than the width in a direction at right angles to the resistance changing face direction Z of the first resistor pattern  4  (shorter side width) H 2 , so that the conductive contacts  11  can be in contact with the entire width H 2  of the resistor pattern. 
     The opening  10   c  of the holding member  10  is in the forming direction of the curved surface  11   a  of the conductive contact  11 , and is formed in the resistance changing face direction Z (longer side of the first resistor pattern  4 ), so as to improve the deformation operation of the conductive contacts  11  by reducing the interference of the leg  10  in the resistance changing face direction Z which is the deforming direction of the conductive contacts  11 . 
     The operating member  12  comprising a synthetic resin form has a grip  12   a , and a flange-shaped support  12   b  formed integrally with the grip  12   a.    
     The operating member  12  causes the grip  12   a  to project outside from the hole  1   a  of the case  1 , and houses the support  12   b  in the case  1 . It places the support  12   b  on the holding portion  10   a  of the holding member  10  and elastically presses the support  12   b  against the inner surface of the case  1  under the effect of elasticity of the holding member  10  and attaches the support  12   b  to the case  1  so as to be capable of pressing. 
     Operation of the variable resistor of the invention having the aforementioned configuration will now be described. First, when the upper surface of the operating member  12  is pressed against elasticity of the leg  10   b , the holding portion  10   a  of the holding member  10  is pressed by the support  12   b . As a result, the leg  10   b  are elastically deformed, and the curved surface  11   a  of the conductive contact  11  comes into contact with the center portion of the first resistor pattern  4 . When the holding portion  10   a  is further pressed, the curved surface  11   a  deforms in the resistance changing face direction. This causes a gradual increase in the contact area with the first resistor pattern  4 , thus making the resistance value on the both ends of the first resistor pattern  4  variable. 
     When the pressing operation of the operating member  12  is released, the holding portion  10   a  recovers the original state thereof under the effect of elasticity of the leg  10   b , and the operating member  12  recovers the original state thereof by elasticity of the legs  10   b . In the meantime, the contact area of the curved surface  11   a  with the first resistor pattern  4  gradually decreases while causing a change in the resistance value, and the curved surface  11   a  recovers the original state thereof. As a result, it is possible to change the resistance value by causing a change in the contact area of the conductive contacts  11 . 
     The change characteristic of pressing force and electric resistance for the first resistor pattern  4  when pressing the operating member  12  is such that, as shown in FIG. 8, scattering between maximum and minimum values of resistance is small, and the change takes the form of an almost linear change curve K 1 , as compared with the change curve K 2  of a pressure-sensitive conductive rubber shown in FIG.  12 . 
     This change curve K 1  is achieved as a result of formation of the variable resistor from the first resistor pattern  4  which gives an accurate resistance value and the configuration in which the change in the contact area is caused by the conductive contacts  11 . 
     Such a variable resistor is incorporated in a game machine and now used, for example, in an electric circuit diagram as shown in FIG.  9 . 
     In this circuit diagram, an output voltage obtained between the first and second resistor patterns  4  and  5  upon impression of a voltage between the third connecting pattern  8  for grounding (GND) and the second conductor pattern  7  for power supply (VCC) is taken out, as derived from the output pattern (OUTPUT) of the first conductor pattern  6 . 
     When using this variable resistor for speed operation of a vehicle in a game machine, for example, the change curve K 1  shows an almost linear change throughout the entire course from the initial stage to the middle stage and the final stage of pressing operation of the operating member  12 . It is therefore possible to conduct easy operation without causing an out-of-tune feeling in the speed operation, and the resistor is applicable for the entire range of the change curve K 1 , with a wide range of pressing operation and satisfactory operability. 
     The aforementioned embodiment has been described with a conductive contact  11  made by mixing carbon with a rubber material. A contact made by providing metal foil on the rubber material surface may also be used, or carbon may be printed on the rubber material. 
     In the variable resistor of the present invention, in which the first resistor pattern  4  forming the variable resistor is used, it is possible to provide a variable resistor with a smaller scattering in the manufacture, a more uniform resistance change property, and higher accuracy. 
     By pressing the holding member  10 , the conductive contact  11  deforms so as to change the contact area relative to the first resistor pattern  4  to change the resistance value. It is therefore possible to bring the change curve K 1  of electric resistance relative to the pressing force closer to the linear form. Particularly, when using the variable resistor of the invention in a game machine, operation free from an uncomfortability is available as compared with a conventional case. It is also possible to use the change curve K 1  as a whole in operation, and therefore a variable resistor operable in a wider range of pressing operation can be provided. 
     In the configuration of the invention, a configuration for always elastically pressing such as a conventional pressure sensitive member is not necessary. It is therefore possible to inhibit scattering of output during non-operation, and thus to provide a variable resistor having a long service life susceptible to a smaller change with time of the conductive contact  11 . 
     Since the fixed resistor is composed of the second resistor pattern  5 , it is possible to form it by printing simultaneously with the first resistor pattern  4 . It is thus possible to provide a lower-cost variable resistor requiring a smaller number of parts, with a higher operability in the manufacture as compared with the conventional one. 
     Because the first resistor pattern  4  which is a variable resistor has a larger resistance value than that for the second resistor pattern  5  which is a fixed resistance, the change in resistance value of the first resistor pattern  4  upon contact with the conductive contact  11  can be relatively increased, resulting in a larger change in output voltage. A variable resistor having a satisfactory operability can thus be provided. 
     The resistor is formed by printing so as to extend across the belt-shaped portion  6   a  of the first conductor pattern  6 . The first and second resistor patterns  4  and  5  are thus formed. Both the first and second resistor patterns  4  and  5  can therefore be simultaneously provided, bringing about a better space factor, a more compact size, and it is possible to form by printing the second resistor pattern  5  which is a fixed resistance and the first resistor pattern  4  which is a variable resistance. 
     Even when the resistance values of the both resistor patterns  4  and  5  fluctuates, such fluctuation is never larger than the design value for one and smaller than the design value for the other, but scattering is in the same manner for the both patterns. It is therefore possible to cancel the scattering, and it is harder for an output to change even for a change in environmental conditions such as a change in temperature. 
     It is thus possible to provide a lower-cost variable resistor requiring a smaller number of parts and giving a higher operability of manufacture as compared with the conventional art. 
     By covering the second resistor pattern  5  which is a fixed resistance with the insulating layer  9 , it is possible to provide a variable resistor in which the conductive contact  11  never comes into contact with the second resistor pattern  5  upon deformation of the conductive contact  11 , and exerts no adverse effect on the properties. 
     The conductive contact  11  is formed with a width H 1  larger than the width H 2  of the rectangular first resistor pattern  4  so that the conductive contact  16  comes into contact with the full rectangular width of the resistor pattern  4 . As a result, the conductive contact  11  comes into contact with the full width of the first resistor pattern  4  upon pressing, thus stabilizing the contact area with the first resistor pattern  4  upon pressing, thus making it possible to provide a variable resistor giving satisfactory accuracy of a change in resistance. 
     Because the conductive contact  11  is formed by mixing carbon with the rubber material, the service life of the conductive contact  11  can be extended. 
     The holding member  10  is made of an elastically deformable rubber material, and the conductive contact  11  is formed integrally with the holding member  10 . It is therefore possible to provide a low-cost variable resistor free from entanglement of the conductive contact  11  and giving a high productivity. 
     The holding member  10  is provided with cylindrical leg  10   b  formed so as to be in contact with the insulated substrate  3  and surround the conductive contact. This leg  10   b  serves also as the return of the conductive contact  11 . It is therefore possible to provide a low-cost variable resistor requiring only a small number of parts and giving a satisfactory assembly property. 
     The leg  10   b  is provided with an opening  10   c  in the forming direction of the curved surface  11   a . It is therefore possible to provide a variable resistor hardly suffering interference by the leg  10   b , improves deforming operation of the conductive contact  11 , with a higher deforming accuracy of the conductive contact  16 .