JP2550774B2 - Variable resistor for high voltage - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a high voltage variable resistor (hereinafter referred to as a variable resistor) used in a TV receiver, a CRT display, etc. Discharge prevention structure

<Prior Art> Conventionally, a variable resistor is attached to a flyback transformer used when configuring a TV receiver,
The variable resistor called the focus pack is generally constructed as shown in the vertical sectional side view of FIG. That is, the variable resistor includes an insulating substrate 10 made of alumina or the like in the shape of a rectangular flat plate, an insulating case 11 which is a resin molding of a one-sided open box housing the same, and a bottom wall 11a of the insulating case 11. A high-pressure side rotating shaft 12 and a low-pressure side rotating shaft 13 that are rotatably held through the shaft.

Then, on the surface of the insulating substrate 10, a resistance pattern
Along with 14, a terminal electrode (not shown) electrically connected to each of its ends is formed, while rotating shafts 12, 13
Sliders 16 and 17 are attached to the inner ends of the sliders 16 to take out a voltage appropriately divided by sliding on the resistance pattern 14.

Reference numeral 18 in the drawing denotes an insulating resin layer, and this insulating resin layer 18 is formed by filling the insulating resin on the back surface side of the insulating substrate 10 so as to hermetically seal the inside of the insulating case 11. Has been done. Reference numeral 19 is an outer case of the flyback transformer to which the variable resistor is attached, and the outer case 19 is also filled with an insulating resin (not shown).

<Problems to be Solved by the Invention> By the way, the above-mentioned conventional variable resistor has the following disadvantages. That is, in this type of variable resistor, the insulation case 11 secures the external insulation. However, there are voids (air bubbles) in the insulation case 11 or cracks on the surface thereof. If so, there is a risk that an external discharge will occur especially in the high voltage side portion of the variable resistor. When the external discharge occurs, smoke or ignition is generated, which may cause fatal damage.

The present invention has been devised in view of such conventional inconveniences, and an object thereof is to provide a variable resistor capable of effectively preventing external discharge.

<Means for Solving the Problems> In order to achieve such an object, a high voltage variable resistor according to the present invention has an insulating substrate having a resistance pattern formed on the surface thereof, and one surface for housing the insulating substrate. A variable resistor for high voltage having an open box type insulating case, wherein a predetermined thickness of an insulating resin is formed on at least the high voltage side inner surface of the resistance pattern of the bottom wall that covers the insulating substrate of the insulating case with a space. On the other hand, while the insulating layer is formed, a groove portion having a predetermined width and having a predetermined depth is formed in the side wall surrounding at least the high voltage side of the resistance pattern of the insulating case.

<Operation> According to the above means, at least the high-voltage side of the resistance pattern on the insulating substrate forming the variable resistor is surrounded by the bottom wall and the side wall of the insulating case, and at the same time, the insulation formed on the inner surface of the bottom wall. It is also surrounded by an insulating layer made of an insulating resin that fills the layer and the groove in the side wall. Since the molding of the insulating case and the formation of the insulating layer by filling the insulating resin are performed in different steps, defects such as voids and cracks may occur at the same position of the insulating case and the insulating layer. I don't get it.

<Example> Hereinafter, an example of the present invention is described based on a drawing.

FIG. 1 is a vertical cross-sectional side view showing a schematic configuration of a variable resistor according to this embodiment, FIG. 2 is a cross-sectional side view taken along the line II-II of FIG. 1, and FIG. It is a partially broken perspective view seen from the side. Since the entire structure of this variable resistor is basically the same as that of the conventional example, parts and portions which are the same as or correspond to those in FIG. 4 are denoted by the same reference numerals in FIGS. Detailed explanation is omitted.

The variable resistor according to the present embodiment penetrates through an insulating case 1, which is a resin molded product having an open-faced box shape, a substantially rectangular insulating substrate 10 housed in the insulating case 1, and a bottom wall 1a of the insulating case 1. And a high-pressure side rotating shaft 12 and a low-pressure side rotating shaft 13 that are rotatably held. Then, on the surface of the insulating substrate 10, a resistance pattern 14 and terminal electrodes (not shown) electrically connected to respective end portions thereof are formed,
Sliders 16 and 17 that slide on the resistance pattern 14 are attached to the inner ends of the rotating shafts 12 and 13, respectively. Although not shown, on the surface of the insulating substrate 10, in addition to the above-mentioned terminal electrodes, terminal electrodes for taking out the voltage divided by the sliders 16 and 17 are also formed.

In addition, an insulating layer 2 having a predetermined thickness filled with an insulating resin is formed on the entire inner surface of the bottom wall 1a that covers the insulating substrate 10 of the insulating case 1 in a spaced manner, while the resistance pattern 14 is formed.
In the side wall 1b of the insulating case 1 surrounding the above, a groove portion 3 having a predetermined depth and having a predetermined width is formed so as to be filled with the insulating resin, except for one side wall on the rotating shaft 13 side. That is, the groove portion 3 is formed to have a depth substantially corresponding to the height of the side wall 1b in which the groove portion 3 is formed. In the groove portion 3, for example, the variable resistor is attached to the outer case 19 of the flyback transformer. After that, the same insulating resin that fills the outer case 19 is filled at the same time to form an insulating layer. In addition, it is desirable that the thickness of the insulating layer 2 is set to such a degree that the insulating layer 2 can secure the breakdown voltage by itself. In addition, the groove 3
It is desirable that the width be set in advance so that the withstand voltage can be secured even if the insulating resin filled therein is alone. Needless to say, the insulating resin may be filled into the groove portion 3 before it is attached to the flyback transformer. Although an epoxy resin is generally used as the insulating resin, the insulating resin is not limited to this and may be the same or different resin material as the insulating case 1.

By the way, in the above description, the insulating layer 2 is formed on the entire inner surface of the bottom wall 1a of the insulating case 1, and the groove portion 3 in the side wall 1b filled with the insulating resin is located on one side of the rotary shaft 13 side. Although it is described that only the side wall is formed, the invention is not limited to this. That is, the insulating layer 2 is a resistance pattern.
It may be formed only on the high pressure side of 14 (rotating shaft 12 side), or the groove 3 may be similarly formed only on the high pressure side. Further, the groove portion 3 may be formed over the entire circumference of the side wall 1b.

Furthermore, since not only the resistance pattern 14 but also terminal electrodes (not shown) are formed on the surface of the insulating substrate 10 housed in the insulating case 1, as shown in FIG. The insulating resin can also be filled in the space S where the terminal electrode on the side is exposed. Also, the number of rotating shafts is not limited to the above-described two axes, and may be one axis or multiple axes of three or more axes. Further, the high voltage variable resistor according to the present invention can be attached to a high voltage generator other than the flyback transformer and used.

<Effect of the Invention> As described above, in the variable resistor according to the present invention, at least the high-voltage side of the resistance pattern formed on the insulating substrate is surrounded by the insulating case, and at the same time,
It is also doubly surrounded by the insulating layer formed on the inner surface of the bottom wall of the insulating case and the insulating layer formed in the groove portion of the side wall. Since the molding of the insulating case and the formation of the insulating layer by filling the insulating resin are performed in different steps, defects such as voids and cracks may occur at the same position of the insulating case and the insulating layer. In the unlikely event that a defect occurs in the insulating case, this defect will be sufficiently compensated by the insulating layer. Further, even if the insulating layer has a defect, no inconvenience occurs if the insulating case has no defect.

Therefore, according to the present invention, it is possible to effectively prevent external discharge due to the double structure of the insulating case and the insulating layer.

[Brief description of drawings]

1 to 3 relate to an embodiment of the present invention. FIG. 1 is a vertical sectional side view showing a schematic configuration of a variable resistor, and FIG.
FIG. 3 is a cross-sectional side view taken along the line II-II in the figure, and FIG. 3 is a partially cutaway perspective view of the insulating case as seen from its open side. FIG. 4 is a longitudinal sectional view showing a schematic configuration of a variable resistor according to a conventional example. In the figure, reference numeral 1 is an insulating case, 1a is a bottom wall, 1b is a side wall,
2 is an insulating layer, 3 is a groove, 10 is an insulating substrate, and 14 is a resistance pattern. In addition, the same reference numerals in the drawings indicate the same or corresponding parts and portions.

Claims (1)

(57) [Claims] 1. A variable high voltage device comprising: an insulating substrate (10) having a resistance pattern (14) formed on a surface thereof; and a one-sided open box type insulating case (1) for housing the insulating substrate (10). A resistor having a predetermined thickness made of an insulating resin on at least the inner surface of the resistance pattern (14) of the bottom wall (1a) covering the insulating substrate (10) of the insulating case (1) at a high voltage side. While forming the insulating layer (2), the side wall (1b) surrounding at least the high-voltage side of the resistance pattern (14) of the insulating case (1) is filled with an insulating resin and has a groove portion of a predetermined depth and a predetermined width ( 3) A variable resistor for high voltage, which is characterized by being formed.