GB2268836A

GB2268836A - Manufacturing high voltage variable resistor

Info

Publication number: GB2268836A
Application number: GB9313741A
Authority: GB
Inventors: Tsugumichi Nagaoka; Nobuyuki Kitakaze; Isao Sunahase
Original assignee: Murata Manufacturing Co Ltd
Current assignee: Murata Manufacturing Co Ltd
Priority date: 1992-07-02
Filing date: 1993-07-02
Publication date: 1994-01-19
Anticipated expiration: 2013-07-02
Also published as: GB9313741D0; GB2268836B; JP3128968B2; JPH0620809A

Abstract

In a high voltage variable resistor in which an insulating substrate 4 is adhered to a supporting step 7 of a casing 1 of the resistor by an adhesive, a firm adhesive fixing is achieved by forming a sleeve 20 on the inside of the insulating casing 1 with an opening of the sleeve facing a hole 22 provided through the insulating substrate 4, and fixing the shank 25 of a fixing pin 23 in the sleeve through the hole 22 of the insulating substrate so that insulating substrate is pressed against the supporting step 7 by the head 24 of the fixing pin. In this condition, an adhesive adhering the insulating substrate 4 to the supporting step 7 is hardened. <IMAGE>

Description

HIGH VOLTAGE VARIABLE RESISTOR AND METHOD OF MANUFACTURING THE SAME This invention relates to a variable resistor and a method of manufacturing the same and, more particularly, to a high voltage variable resistor wherein an insulating substrate is adhered and fixed firmly to a supporting step of a casing.

A high voltage variable resistor, as shown in Figs.

4-6 as a basic structure, comprises an insulating casing 1 made from a synthetic resin and of which one side is open, an insulating substrate 4 on the surface of which is provided a metal glaze resistor 2 of a required pattern having an electrode 3 at both ends, and so on, and a rotary shaft 5 having a slider 9 on the end which is fitted to the casing 1. The insulating substrate 4, which has a lead terminal 6 connected to the electrode 3, is fitted in the casing 1. An overlapping part of the insulating substrate 4 and a supporting step 7 in the form of a closed loop about the inside of the casing 1 are stuck to each other by an adhesive which is thermohardened, and a resin 8 is molded on the open side of the casing 1. Numeral 10 is a rib for preventing discharge.

When the insulating substrate 4 is adhered to the supporting step 7 by an adhesive, since the insulating substrate 4 rises by a spring pressure of the slider 9, it is necessary to press down the substrate until the adhesive is hardened. Conventionally, as measures for pressing down the substrate, a jig was used and the jig was removed after the adhesive was hardened. Therefore, there was a problem that the process was complicated.

Further, in the case where a high voltage capacitor was disposed on the back side of the substrate 4, there was a problem that it was difficult to fit the jig to press down on the substrate.

Therefore, it is an object of the present invention to provide a novel high voltage variable resistor and a method of manufacturing the same for solving the above mentioned problems.

The present invention consists in a variable resistor comprising an insulating casing having a supporting step, preferably, in the form of a closed loop or endless step, and a sleeve formed on the inside of the casing, an insulating substrate having a hole, and a fixing pin, said fixing pin being fixed into the sleeve of the insulating casing through the hole of the insulating substrate and an adhesive adhering the insulating substrate to the supporting step.

The invention also consists in a method of manufacturing a variable resistor which comprises an insulating casing having a supporting step, and an insulating substrate, on which are provided at least one electrode and a metal glaze resistor, adhered to the supporting step wherein a sleeve is formed on the inside of the insulating casing with an opening of the sleeve facing towards a hole provided through the insulating substrate a shank or spindle of a fixing pin having a head is fixed in the sleeve through the hole of the insulating substrate, simultaneously the insulating substrate is pressed on the supporting step by the head of the fixing pin, and an adhesive adhering the insulating substrate to the supporting step is hardened in this condition.

The sleeve may be formed on the inside bottom of the casing and the hole is provided through the insulating substrate in a position corresponding to the sleeve when the insulating substrate is fitted onto the supporting step of the casing. The shank of the fixing pin having a head on one end is fixed into the sleeve through the hole of the insulating substrate and simultaneously the insulating substrate is pressed down by the head of the fixing pin.

Accordingly, the insulating substrate is pressed on the supporting step of the casing and movement of the insulating substrate away from the supporting step under the action of the spring pressure of a slider is prevented. As a result, it is unnecessary to employ a jig, such as used hitherto, for pressing down on the substrate until the adhesive is hardened. Even after the adhesive has hardened, the fixing pin remains in place, and the open surface of the case is filled with a resin to complete the variable resistor.

In order that the present invention may be more readily understood reference will now be made, by way of example, to the accompanying drawings, in which: Fig. 1 is a sectional view of a variable resistor embodying the present invention, Fig. 2 is a plan view of an insulating casing, Fig. 3 is a perspective view of a sleeve provided on the inside bottom of the insulating casing, Fig. 4 is a sectional view of a conventional variable resistor, Fig. 5 is a reverse side view of an insulating substrate of the conventional variable resistor, and Fig. 6 is a plan view of an insulating casing of the conventional variable resistor.

In Fig. 1 - Fig. 3, a sleeve 20 is formed on the inside bottom of an insulating casing 1 made from a synthetic resin of which one surface is open and an opening 21 of the sleeve 20 faces a hole 22 provided through an insulating substrate 4 and a shank 25 of a fixing pin 23 having a head 24 is pressed and fixed into the sleeve 20 through the hole 22 of the insulating substrate 4 and the insulating substrate 4 is pressed on a supporting step 7 by the head 24 of the fixing pin 23 and, in this condition, an adhesive adhering the insulating substrate 4 to the supporting step 7 is hardened. The adhesive is applied to the supporting step 7 in advance before the insulating substrate 4 is fitted in the casing 1.

A form in which a part of the supporting step 7 can be indented toward the inside direction so that a fixed electrode 3 as shown in Fig. 5 can be placed on the outside of a closed loop formed by the supporting step 7 can be employed. The fixing pin 23 remains after the adhesive is hardened and a resin 8 is filled in the open surface of the insulating casing 1 and hardened.

Further, a metal glaze resistor 2 having a required pattern, electrodes 3 at both the ends, and so on, are provided on the insulating substrate 4, as the conventional example shown in Fig. 4 - Fig. 6, and a rotary shaft 5 having a slider 9 on the end surface is fitted to the insulating casing 1, and the insulating substrate 4 having the electrode 3, to which a lead terminal 6 is connected, is fitted in the casing 1. The lead terminal 6 can be a lead and it is not always necessary to draw out the lead terminal from the open surface side of the casing 1. The lead terminal 6 can be drawn out from the side or the bottom of the casing 1. Further, in the case where a conductive rubber, and so on, is disposed so as to contact the electrode 3, the lead terminal 6 can be inserted and fitted into the conductive rubber, and so on, after the insulating substrate 4 is adhered to the supporting step 7.

A split 26 is provided in the sleeve 20 shown in Fig. 2 and Fig. 3 and the fixing pin 23 can be pressed and fixed into the sleeve more firmly by the split 26.

Further, the fixing pin 23 can be fixed into the sleeve 20 not only by inserting with pressure but also by screwing.

In other words, as long as the fixing pin 23 and the sleeve 20 can be fixed to each other mechanically, any fixing structure is acceptable and a soft resin, such as a modified PPO resin, is preferable as the material of the fixing pin 23.

The height of the sleeve 20 is as high as the height from the inside bottom of the insulating casing 1 to the supporting step 7 or is lower than that, and a rib 10 for preventing discharge has the same height as the supporting step 7. Further, the rib 10 for preventing discharge is not essential to the insulating casing. The resin 8 on the open surface of the insulating casing 1 is also not essential.

As mentioned above, according to the present invention, in the case where the insulating substrate is adhered to the supporting step of the insulating casing by an adhesive, a complex process in which a jig for pressing down the insulating substrate is used until an adhesive is hardened, whereupon the jig is removed, is avoided and a simple hardening process and a firm adhesive fixing are available since the fixing pin having the head is fixed into the opening of the sleeve provided on the inside bottom of the insulating casing through the hole of the insulating substrate, and the insulating substrate is pressed on the supporting step of the casing by the head of the fixing pin and, in this condition, an adhesive adhering the insulating substrate to the supporting step is hardened.

Claims

1. A variable resistor comprising an insulating casing having a supporting step, a sleeve formed on the inside of the casing, an insulating substrate having a hole, and a fixing pin, said fixing pin being fixed into the sleeve of the insulating casing through the hole of the insulating substrate, and an adhesive adhering the insulating substrate to said supporting step.

2. A method of manufacturing a variable resistor which comprises an insulating casing having a supporting step, and an insulating substrate, on which are provided at least one electrode and a metal glaze resistor, adhered to the supporting step, wherein a sleeve is formed on the inside of the insulating casing with an opening of said sleeve facing a hole through the insulating substrate, a shank of a fixing pin having a head is fixed in the sleeve through the hole of the insulating substrate, simultaneously the insulating substrate is pressed on the supporting step by the head of the fixing pin and, in this condition, the adhesive adhering the insulating substrate to the supporting step is hardened.

3. A variable resistor constructed substantially as hereinbefore described with reference to the accompanying drawings.

4. A method of manufacturing a variable resistor, substantially as hereinbefore described with reference to the accompanying drawings.