Patent Publication Number: US-6041497-A

Title: Method of making a connection terminal

Description:
This application is a divisional of application Ser. No. 08/882,295, filed Jun. 25, 1997. 
    
    
     BACKGROUND OF THE INVENTION 
     This application corresponds to Japanese Patent Application No. 8-167530 filed on Jun. 27, 1996, which is hereby incorporated by reference in its entirety. 
     1. Field of the Invention 
     The present invention relates to a high-voltage variable resistor used to adjust the focus voltage, screen voltage, etc. of a television receiver or like device. 
     2. Description of the Related Art 
     FIGS. 4 through 6 show the structure of an example of a conventional high-voltage variable resistor of the above-mentioned type. In this device, the connection between an electrode formed on a substrate and lead lines is possible without performing soldering. FIG. 4 is a sectional side view of a high-voltage variable resistor. FIG. 5 is an exploded perspective view showing a connection terminal holding structure. FIG. 6 is a sectional view showing the main components of a connection structure using a connection terminal. 
     As shown in FIG. 4, in this high-voltage variable resistor, an insulating substrate 2 formed of a ceramic material, such as alumina, is glued and fixed to a step section formed in the inner periphery of an insulating case 1 having one side open and formed of a synthetic resin. Rotation shafts 5 to which sliding members 4 are mounted are rotationally supported by cylindrical bearings 1a provided on the front side of the insulating case 1. An epoxy-type resin coating 3 is formed by molding on the open side of the insulating case 1 and on the back side of the insulating substrate 2 (which is shown on the upper side in the drawing). 
     A lead line holding cylinder 1b is provided on the insulating case 1, and a connection terminal accommodating section 6 is provided inside the insulating case 1 and at the base of the lead line holding cylinder 1b. The connection terminal accommodating section 6 accommodates a connection terminal 7, which is in contact with and electrically connected to a terminal electrode formed on the surface of the insulating substrate 2. An output lead line 8 for extracting a focus voltage and a screen voltage is inserted into the lead line holding cylinder 1b, and the lead line 8 inserted into this cylinder is connected to the connection terminal 7. 
     As shown in the enlarged views of FIGS. 5 and 6, the connection terminal 7 is formed by punching (e.g. stamping) the part out from a flat metal plate. The connection terminal 7 has a substantially rectangular lead line connecting section 7a at the center of which a plurality of holding members 7c are formed. The connection terminal 7 also includes a spring portion 7b bent into a curved configuration. 
     The spring portion 7b, which protrudes from the center of one side of the lead wire connecting section 7a toward the insulating substrate 2, is formed having a predetermined width which is smaller than the width of the lead line connecting section 7a in order to obtain the requisite elasticity. 
     The lead line connecting section 7a of the connection terminal 7 is held in a terminal holding groove 6a of the connection terminal accommodating section 6, and a part of the spring portion 7b is held in contact with an output terminal electrode 2a of the insulating substrate 2 and pressed against the insulating substrate 2. In this state, the connection terminal 7 is accommodated in the connection terminal accommodating section 6 and secured in position therein. A core wire 8a of the lead wire 8 inserted into the lead wire holding cylinder 1b is held by the holding members 7c to thereby provide electrical connection with the connection terminal 7. 
     Although not shown on the surface of the insulating substrate 2 (i.e., the lower surface thereof as seen in FIG. 4), there is formed an input terminal electrode to which high voltage is input, a grounding terminal electrode, an output terminal electrode for focus voltage and screen voltage, etc., and a resistor (e.g. film resistor) having a predetermined pattern. For example, the film resistor may comprise an arcuate variable resistor portion formed between the input terminal electrode and the grounding terminal electrode. One end of each sliding member 4 is arranged so as to slide on the variable resistor portion of the film resistor. Further, although not shown, lead terminals or lead wires for grounding and inputting high voltage are connected to the terminal electrodes by soldering, by contact with a conductive rubber member, or the like, and are led out from the open side of the insulating case 1. 
     However, in the above-described conventional high-voltage variable resistor, the connection terminal 7 and the terminal electrode 2a of the insulating substrate 2 are held in contact only at the limited surface region where the spring portion 7b contacts the terminal electrode 2a. Typically, this contacting surface region between the spring portion 7b and the terminal electrode 2a is quite small, and may form a limited contact line or point. When there exists insulating foreign matter such as adhesive material in the contact region between the connection terminal 7 and the terminal electrode 2a, the contact state becomes unstable, resulting in defective conduction, etc. 
     SUMMARY OF THE INVENTION 
     It is accordingly an object of the present invention to provide a high-voltage variable resistor which makes it possible to achieve stable and reliable contact conduction between the connection terminal and the terminal electrode. 
     To achieve the above object, there is provided, in accordance with a first aspect of the invention, a high-voltage variable resistor comprising: (a) an insulating case having at least one open side, which includes a connection terminal accommodating section; (b) an insulating substrate provided in the insulating case, the substrate having a surface, wherein a resistor and an electrode are formed on the surface; (c) a rotation shaft which is rotationally supported by the insulating case, wherein the rotation shaft is equipped with a sliding member; and (d) a connection terminal which is provided in the connection terminal accommodating section and which detachably connects the electrode to an input/output lead line. The connection terminal includes a spring portion bent into a curved form, and the spring portion includes a contact section which has at least one protrusion held in press contact with the electrode. 
     In accordance with another aspect of the invention, there is provided a high-voltage variable resistor comprising: (a) an insulating case having at least one open side, which includes a connection terminal accommodating section; (b) an insulating substrate provided in the insulating case, the substrate having a surface, wherein a resistor and an electrode are formed on the surface; (c) a rotation shaft which is rotationally supported by the insulating case, wherein the rotation shaft is equipped with a sliding member; and (d) a connection terminal which is provided in the connection terminal accommodating section and which detachably connects the electrode to an input/output lead line. The connection terminal has a spring portion bent into a curved form, the spring portion having at its forward end a contact section which is wider than other portions of the spring portion, wherein the contact section is arranged in parallel with a plane of the electrode, further wherein the contact section includes a plurality of protrusions held in press contact with the electrode. 
     In accordance with a third aspect of the invention, an electrical component is provided comprising: (a) a casing having a connection terminal accommodating section disposed therein and an opening for feeding a lead line to the connection terminal accommodating section; (b) an electrode formed on a substrate, at least a portion of which can be accessed from the connection terminal accommodating section; and (c) a connection terminal disposed within the connection terminal accommodating section for connecting the lead line with the electrode. The connection terminal, in turn, includes: (c1) a lead line connection section for forming an electrical contact with the lead line; (c2) a spring portion extending from the lead line connection section, the spring portion terminating in a contact section; and (c3) one or more protrusions extending from the contact section for resiliently contacting the electrode. 
     A fourth aspect of the invention pertains to the above-identified connection terminal itself. A fifth aspect of the invention pertains to a method of making the connection terminal comprising steps of: (a) providing a flat metal sheet; (b) stamping out the connection terminal from the flat metal sheet, the connection terminal comprising a lead line connection section and a spring portion which terminates in a contact section; (c) punching out one or more protrusions from the contact section; and (d) bending the spring portion into a curved shape. 
     In accordance with the invention as described above, at least one protrusion is provided on the contact section of the spring portion of the connection terminal. This structure reduces the possibility of foreign matter adhering to the contact surface. Further, even if foreign matter adheres to the protrusion, the protrusion is brought into contact with the electrode of the insulating substrate such that the protrusion slightly digs into (e.g. penetrates) the electrode, so that a defective contact due to the adhesion of foreign matter is mitigated, thereby making it possible to achieve stable and reliable contact conduction between the connection terminal and the electrode. That is, by providing the contact section of the connection terminal with one or more protrusions, the surface area of the spring portion which contacts the electrode is reduced to thereby increase the contact pressure, whereby foreign matter is prevented from existing in the contact section. 
     In accordance with the invention, the contact section situated at the forward end of the spring portion of the connection terminal is formed having a larger width than other parts of the spring portion, and a plurality of protrusions are provided on this contact section. Thus, line contact (where the contact spans the length of a line) or point contact is effected at a plurality of positions over a wider range, so that a defective contact due to the adhesion of foreign matter is substantially mitigated, thereby making it possible to achieve stable and reliable contact conduction. That is, in the connection terminal of the present invention, the contact section is formed having a large width so that the contact range is increased, and, by providing a plurality of protrusions, a multi-point contact is provided. Further, the area of each region where the connection terminal contacts the electrode is reduced to thereby increase the contact pressure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing, and other, objects, features and advantages of the present invention will be more readily understood upon reading the following detailed description in conjunction with the drawings in which: 
     FIG. 1 is a perspective view of an exemplary connection terminal according to a first embodiment of the present invention; 
     FIG. 2 is sectional view showing main components of a connection structure of a high-voltage variable resistor employing the connection terminal of the first embodiment of the present invention; 
     FIG. 3 is a perspective view of an exemplary connection terminal according to a second embodiment of the present invention; 
     FIG. 4 is a sectional side view of a conventional high-voltage variable resistor; 
     FIG. 5 is an exploded perspective view showing a conventional connection terminal holding structure; and 
     FIG. 6 is a sectional view showing the main components of a connection structure for use with a conventional connection terminal. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Embodiments of the present invention will now be described with reference to the drawings. In the drawings, the components which are the same as those of the above-described conventional example and the components having the same functions as those of the conventional example are indicated by the same reference numerals. 
     FIGS. 1 and 2 show a connection terminal of a high-voltage variable resistor according to the first exemplary embodiment of the present invention and a connection structure using the connection terminal, respectively. 
     As shown in FIGS. 1 and 2, in the high-voltage variable resistor of this embodiment, the spring portion 7b of the connection terminal 7 has at its forward end a contact section 7d which is wider than the other parts of the spring portion 7b. Protrusions consisting of four protruding members 7e are formed on this contact section 7d. According to exemplary embodiments, the contact section 7d is formed as a substantially rectangular planar section, and is integrally connected to the spring portion 7b. When employed in a connection structure, the contact section 7d is disposed in parallel with the surface of the insulating substrate 2. The protrusions 7e can be formed by punching (e.g. stamping) the protrusions out of the contact section 7d into a predetermined configuration, and then bending the protrusions so that they protrude outward from the face of the contract section 7d toward the lower face of the insulating substrate 2. For instance, in the specific embodiment shown in FIG. 1, the protrusions are substantially rectangular-shaped. The protrusions are formed by punching out -shaped patterns in the contact section 7d and then bending the metal enclosed by the -shaped patterns outward. Alternatively, the punching and bending can be performed in one operation. 
     The connection terminal 7 is accommodated in and fixed to the connection terminal accommodating section 6. When the connection terminal 7 is disposed in the accommodating section 6, the outer edge portion of the lead line connecting section 7a is held in the connection terminal holding groove 6a of the connection terminal accommodating section 6. In this state, the protrusions 7e are held in contact with the output connection terminal 2a of the insulating substrate 2, which presses against the protrusions 7e. In one embodiment, the contact pressure can be set so that protrusions 7e slightly dig into (e.g. penetrate) the electrode 2a. The core wire 8a of the lead line 8, inserted into the lead wire holding cylinder 1b, is held by the holding members 7c and is thereby connected to the connection terminal 7. 
     Apart from the construction of the above-described connection terminal 7, the construction of this embodiment is the same as that of the conventional example, and a further description thereof will be omitted. 
     In the construction of this embodiment, the contact section 7d is formed so as to be flat and wide so that the range of contact surface facing the output terminal electrode 2a is enlarged. Further, electrical contact with the output terminal electrode 2a is effected with a plurality of protrusions 7e, so that defective contact due to adhesion of foreign matter is substantially decreased. That is, the point of contact extends over a wide range and contact is effected at a plurality of positions, so that, even when foreign matter adheres to a part of the protrusions, a stable contact can be achieved at other contact positions. Further, the contact area at which each protrusion 7e contacts the terminal electrode 2a is small so that foreign matter is not easily allowed to adhere to each protrusion 7e. Even when foreign matter adheres, it is easily detached from the contact section. Further, the contact pressure at each contact section is high, so that the possibility of defective contact due to adhesion of foreign matter is substantially reduced, thereby making it possible to achieve a stable and reliable contact conduction. 
     In the above-described exemplary embodiment, the width of the contact section 7d of the connection terminal 7 is larger than the width of the other parts of the spring portion 7b. However, other configurations are possible. For instance, the width of the contact section 7d may have the same width as the spring portion 7b. Furthermore, the contact section 7d can be formed in shapes other than as depicted in FIG. 1. 
     The configuration (e.g. shape), number, and positioning of the protrusions 7e can be varied from the embodiment shown in FIG. 1. At least one protrusion on the contact section 7d will suffice. For example, by varying the configuration of the contact section 7d held in contact with the electrode 2a, it is possible to vary the contact area at each protrusion 7e. Further, it is also possible to vary the spring pressure of the protrusions 7e by varying the width, length, etc. of the protrusions 7e, making it possible to achieve optimum contact conduction in accordance with the configuration and material of the electrode. 
     Next, FIG. 3 shows the construction of a connection terminal 7 according to the second exemplary embodiment of the present invention. As shown in FIG. 3, in the connection terminal of this embodiment, a large number of cone-shaped protrusions 7f are formed on the contact section 7d provided at the forward end of the spring portion 7b. Each protrusion 7f is formed by press molding using a punch (e.g. a die) with a pointed forward end or by like technique. When the connection terminal 7 is mounted in a connection structure, the protrusions 7f protrude toward the insulating substrate. The protrusions 7f can also form separate conductive elements which are affixed (e.g. metallurgically bonded) to the contact section 7d. 
     Apart from the construction of the above-described protrusions, the construction of the second embodiment is the same as that of the first embodiment, and further description thereof will be omitted. As with the first embodiment, in the connection terminal of the second embodiment, the protrusions 7f are held in point contact with the electrode 2a at a plurality of positions over a wide range, and the contact area at each point of contact with the electrode 2a is small, so that it is possible to achieve a stable and reliable contact conduction. 
     The number and configuration (e.g. shape) of the protrusions 7f can be varied from the specific exemplary embodiment shown in FIG. 3. Specifically, the number and configuration of the protrusions 7f can be set to suit the requirements of a particular application of the connection terminal 7. For example, by varying the configuration of the contact section 7d with which the protrusions 7f are held in contact with the electrode 2a (the contact area), it is possible to vary the contact pressure of each of the points of contact. 
     Further, in the above-described embodiments, the contact section 7d of the connection terminal 7 is shown as substantially rectangular. However other shapes can be used, such as a disc-like, oval, triangular or other shape. 
     As discussed above, the method of manufacturing the connection terminals 7 can comprise steps of first punching (e.g. stamping) the connection terminals 7 from a flat sheet of metal. Thereafter, the protrusions can be punched out and, in the case of the first embodiment, bent to their proper configurations. Thereafter, the spring portion can be bent to its proper curved configuration. The order of these steps can be varied, or one or more steps can be performed simultaneously. 
     As described above, in the high-voltage variable resistor of the present invention, at least one protrusion is provided on the contact section of the spring portion of the connection terminal. The possibility of foreign matter adhering to this protrusion is reduced, compared to the above-described conventional terminal. Further, even when foreign matter adheres thereto, the protrusion is held in contact with the electrode so as to slightly dig into (e.g. penetrate) the electrode material, so that defective contact due to the adhesion of the foreign matter is mitigated, thereby making it possible to achieve a stable and reliably contact conduction. 
     Further, by enlarging the width of the contact section and forming a plurality of protrusions thereon, it is possible to effect contact extending over the length of a line or contact at a point at a plurality of positions over a wide range, so that defective contact due to adhesion of foreign matter is substantially mitigated, thereby making it possible to achieve a stable and reliable contact conduction. 
     Further, by varying the configuration, number, etc. of the protrusions, it is possible to vary the contact pressure, etc. at each protrusion, thereby making it possible to cope with a variety of connecting conditions. 
     Although the present invention has been described within the context of a high-voltage variable resistor, those skilled in the art will appreciate that the connection terminal disclosed herein can be used in other electrical components. 
     Generally, the above-described exemplary embodiments are intended to be illustrative in all respects, rather than restrictive, of the present invention. Thus the present invention is capable of many variations in detailed implementation that can be derived from the description contained herein by a person skilled in the art. All such variations and modifications are considered to be within the scope and spirit of the present invention as defined by the following claims.