JPH0429521Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Field of Application> This invention relates to a high-voltage variable resistor, and particularly relates to the structure of a case portion that houses an insulating substrate.

<Prior art> A high-voltage variable resistor has a basic structure as shown in FIGS. 1 to 3, which includes an insulating case 1 made of synthetic resin with one side open and a film resistor with a desired pattern on the surface. 2, an insulating substrate 4 with electrodes 3 on both ends thereof, and a rotary shaft 5 with a slider on the end surface attached to the case 1, the insulating substrate 4 with lead terminals 6 connected to the electrodes 3 is attached to the case 1. 1, the overlapping part of the insulating substrate 4 and the support step 7 provided in a closed loop inside the case 1 is pasted with adhesive and heat cured, and then a resin 8 is placed on the open side of the case 1. It is formed by molding.

By the way, when the insulating substrate 4 is pasted inside the case 1 with adhesive, the internal space inside the case 1 is sealed.
Air in the closed space expands when the adhesive heat-cures.

The expanded air flows out of the case 1 from the overlapping surface of the insulating substrate 4 and the support step 7, and at this time blows away the adhesive, so there is no gap between the overlapping surfaces of the insulating substrate 4 and the support step 7. This causes an inconvenience in that the resin 8 enters the inside of the case 1 during molding.

In order to prevent such inconvenience from occurring, an air vent 9 is provided at an appropriate position of the case 1, and the air vent 9 releases the expanding air during the heat curing of the adhesive or resin molding to the outside of the case 1. After resin molding, the air vent 9 is sealed.

By the way, in recent years high voltage variable resistors,
There is a growing demand for cost reduction and miniaturization without deteriorating performance, and for this reason, it has become necessary to improve the voltage resistance between the film resistor 2 and the electrodes 3 provided on the insulating substrate 4.

In particular, the most important issue is improving the withstand voltage of the electrode 3 to which the lead terminal 6 that is drawn out to the outside of the case 1 is soldered, and this part must be isolated from other electrodes and film resistors.

For this reason, it is conceivable to provide discharge prevention ribs 10 and 11 inside the case 1 as shown in FIGS. 4 and 5, and to fix the overlapping surfaces of the ribs 10 and 11 and the insulating substrate 4 with adhesive. It's happening.

However, when the ribs 10 and 11 are provided in the case 1, the spaces surrounded by the ribs are sealed by pasting the insulating substrate 4, and these sealed spaces are not provided in the case 1. Since there is no communication with the air vent 9, the air in the sealed space inside the rib expands during the heat curing process of the adhesive as described above, causing the same problem as described above.

<Problem to be solved by the invention> This invention was made to solve the above problem, and it forms an air vent in the discharge prevention rib provided inside the case, and the space surrounded by the rib. The object of the present invention is to provide a high-voltage variable resistor that can be electrically connected to the outside of the case through an air vent provided in the case, and can allow expanded air to flow out of the case during thermosetting of the adhesive.

<Means for solving the problem> This invention is based on an insulating substrate in which a support stage is provided in a closed loop shape within an insulating case with one side open to which a rotating shaft is attached, and a film resistor having a variable resistance part and an electrode are provided. A high-voltage variable resistor is made by attaching the resistor to its support step with adhesive and molding resin on the open side of the insulating case. A discharge prevention rib shaped to surround the electrode of the substrate and a discharge prevention rib shaped to partition the variable resistance part of the film resistor across the inside of the insulating case are formed, and a part of the discharge prevention rib is formed on these discharge prevention ribs. A notch is formed to form an air vent communicating with the inside of the insulating case, and the insulating substrate is also attached to these discharge prevention ribs with an adhesive.

<Example> This invention will be described below with reference to figures 6 to 10 of the attached drawings.
Description will be given based on the embodiment shown in the figures.

As shown in FIG. 6, a supporting step 7 of an insulating substrate is provided in a closed loop inside an insulating case 6 made of synthetic resin. ribs 10 and 11 are provided.

The installation position and shape of the discharge prevention ribs 10 and 11 are set to correspond to the pattern of the film resistor provided on the insulating substrate and the position of the electrode. In order to accommodate an insulating substrate formed in a pattern constituting a resistor section and provided with electrodes at the four corners, discharge prevention ribs 10 are provided at the four corners of the case 1 in a shape that surrounds the electrodes. Discharge prevention ribs 11 each having a shape that partitions the variable resistance portion of the body are provided.

Each of the discharge prevention ribs 10 and 11 has an air vent 1 that is partially cut out and communicated with the inside of the insulating case.
2, and the case 1 is also provided with an air vent 9, which communicates with the outside of the insulating case, such as a hole, at an appropriate position such as on the bottom surface.

When the insulating substrate is assembled into the case 1 and the overlapping surfaces of the support step 7 and the discharge prevention ribs 10, 11 and the insulating substrate are bonded together with adhesive, each space separated by the discharge prevention ribs 10, 11 is formed. is air vent 1
2 and the outside through the air vent 9 of the case 1, and the expanded air in each space during the heat curing process of the adhesive and resin molding is carried out through the air vent 12,
9 to the outside, thus preventing the adhesive from being blown away by the bulging air or causing mechanical strain to the constituent materials.

The shape, location and number of air vents 12 provided on the discharge prevention ribs 10 and 11 can be freely selected within the range that does not impair the discharge prevention function.
7 to 10 illustrate some examples of air vents 12 for the discharge prevention rib 10.

In the example shown in FIG. 7, a semicircular or V-shaped groove is provided at one location on the upper edge of the discharge prevention rib 10, and the eighth
The example shown in the figure is formed by providing grooves similar to those described above at two locations.

Further, in the example shown in FIG. 9, the discharge prevention rib 10
A long groove is formed along the longitudinal direction of the first
In the example shown in FIG. 0, a horizontal hole is formed in the middle of the rib 10.

In addition, a discharge prevention rib 1 that surrounds the electrode
0 does not necessarily need to be formed for all electrodes, and may be formed only for predetermined electrodes.

In this way, when forming the discharge prevention rib 10 only for a predetermined electrode, the support step 7 for the other predetermined electrodes is wrapped around the inside of the case 1, and the electrode is placed outside of the support step 7. It is also possible to cover the electrode with resin.

Furthermore, the air vent 9 provided in the case 1 is
It is not limited to being formed on the bottom surface of the case as in the above embodiment, but may also be formed around the rotating shaft 5, for example.

In such a case, it is not necessarily necessary to seal the air vent afterward.

<Effects of the invention> As described above, this invention has the above-mentioned configuration, and therefore has the following effects.

(1) In a variable resistor with an insulating substrate housed in a case with air vents installed in appropriate places and a rotating shaft attached to the case, the air vents are formed in the discharge prevention ribs provided inside the case, so the insulation During thermosetting of adhesive and resin molding for bonding the board to the support steps and ribs of the case,
Expanded air in the space surrounded by discharge prevention ribs can flow out of the case.
There is no need to blow away the adhesive or lift the insulating substrate with expanding air.

(2) Since the adhesive will not be blown away by the expanded air during thermal curing of the adhesive or resin molding, or the insulating substrate will not be lifted from the adhesive, the resin on the open side of the case will not adhere to the case during molding. It can prevent it from flowing inside.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view showing a conventional variable resistor, Figure 2 is a back view of the insulating substrate used in the same, Figure 3 is a plan view of the case, and Figure 4 is a discharge prevention rib provided on the same. 5 is a plan view of the same case as above, FIG. 6 is a plan view showing the case of the variable resistor according to this invention, and each of FIGS. FIG. 6 is a perspective view showing different examples of air removal. DESCRIPTION OF SYMBOLS 1... Case, 2... Film resistor, 3... Electrode, 4... Insulated substrate, 5 Rotating shaft, 7... Support step, 9 Air vent, 10, 11... Discharge prevention rib, 12... ...Air removal.

Claims (1)

[Scope of utility model registration request] A support step is provided in a closed loop in an insulating case that is open on one side and a rotating shaft is attached, and an insulating substrate on which a film resistor having a variable resistance part and an electrode are attached is attached to the support step with adhesive. It is a high voltage variable resistor made by molding resin on the open side of the insulating case, and has a shape that surrounds the electrode of the insulating substrate in the part surrounded by the support step inside the insulating case. Discharge prevention ribs are formed across the inside of the insulating case to partition the variable resistance section of the film resistor, and a portion of these discharge prevention ribs is cut out to allow air to communicate with the inside of the insulating case. A high-voltage variable resistor characterized in that a cutout is formed and an insulating substrate is also attached to these discharge prevention ribs with an adhesive.