JPH0428205A - High tension variable resistor - Google Patents

Abstract

PURPOSE:To improve the damp-proof property of a high-tension resistor, and to enhance reliability by a method wherein the resistor forming surface of the insulated substrate, protruding from the frame part of an insulating housing, is coated with silicone rubber, and the opposite surface is coated with flexible epoxy resin. CONSTITUTION:The stepped part formed in an auxiliary insulated housing 11 is formed in the same level as the upper edge of the aperture part of a frame part 5a. After an epoxy resin bonding agent has been applied to the upper edge of the aperture part of the frame part 5a and the upper surface of the stepped part in the housing 11, a resistor 2 and an electrode 3 are provided on the above-mentioned surface, a porcelain insulated substrate 1, on which external connection terminals 4 and 4a are connected and fixed, is placed on an electrode, and it is adhesively sealed. The space formed between a part of the insulated substrate 1 and the housing 5, and a part 2a of a high tension resistor 2 is formed on the surface which is brought into contact with the above-mentioned space. Besides, an aperture part 13 is provided on the housing 11 in the same direction as the aperture part of the insulated housing 5. After self-adhesive silicone rubber 12 has been filled up and hardened in the above-mentioned space from the aperture part 13, flexible epoxy resin 8 is filled up and hardened in the insulated housing 5 excluding the frame part 5a.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high voltage variable resistor used in color television receivers (hereinafter referred to as CTV) and the like.

Conventional technology Figures 12 to 1 regarding the configuration of a conventional high-voltage variable resistor.
This will be explained with reference to FIG.

In the figure, reference numeral 1 denotes an insulating substrate made of ceramic, on the surface of which a resistor 2 and an electrode 3 are formed.

Reference numeral 4 denotes an external connection terminal, which is connected and fixed to the electrode 3.

Reference numeral 5 denotes an insulating casing made of insulating resin, a part of which is formed with a frame 53 that protrudes from the bottom surface, and an operating knob 6 is inserted into the opening of the frame 53 in the frame 5a and rotated. It is freely supported, and furthermore, a brush 7 is fixed to the operating knob 6. The insulating board] is housed in the insulating casing 5 and the frame part 5
It is fixedly sealed on the top part a with an adhesive (not shown).

The insulating substrate 1 has a frame portion 5. Larger frame 5. The other parts of the insulating casing 5 are covered. Epoxy resin 8a is filled so as to cover the surface A+ of the insulating substrate 1 on which the resistor 2 is formed and the 31st surface on which the resistor 2 is not formed.

Such a high voltage resistor is generally combined with a flyback transformer (hereinafter referred to as FBT) as shown in FIG. That is, after the insulating casing 5 of the high-voltage variable resistor is fitted and sealed into the FBT insulating casing 9, the epoxy insulating resin 10 is filled, hardened, and integrated.

Problems to be Solved by the Invention However, the conventional high-voltage variable resistor described above has a problem in that the high-voltage resistor section has poor moisture-proof insulation. The high-voltage variable resistor R is used in the high-voltage circuit of a CTV as shown in Figure 7, and the high-voltage output voltage of the FBT is 25 to 30 K.
VDC is supplied to the anode of a color cathode ray tube (hereinafter referred to as CRT), and is also applied to the terminal tubes of the high-voltage variable resistor R shown in the figure. , the screen adjustment voltage is output from terminal ■. In general, the focus voltage requires about 25 to 30% of the anode voltage, so the resistor R, + that makes up the high voltage variable resistor has a voltage of about 17 to 21 KV.
A DC voltage will be applied. As shown in Figure 13,
The resistor 2 (R+) is formed on the surface of a portion 13 of the insulating substrate 1. Further, as shown in FIG. 12, a portion 13 of the insulating substrate 1 and the resistor 2a (R+) formed thereon are covered with an epoxy resin 83. FIG. 8 shows an example of the results of an accelerated moisture resistance load life test of such a conventional high voltage variable resistor. That is, 30 K is applied to the high voltage variable resistor under the following conditions: 5 ambient temperature 85°C 1 relative humidity 85%
When the voltage V DC is applied in a cycle of 1.5 hours of application and 0.5 hours of no application, the resistance value increases significantly in a short period of time as seen in the figure. This is resistor 2
Since the interfacial adhesive force between the resistor 3 and the epoxy resin 82 decreases with temperature and humidity, a short circuit occurs on the surface of the resistor 23, which damages the resistor surface and eventually leads to a disconnection state. Also, a part 13 of the insulating substrate 1 and the epoxy resin 8. Since the interfacial adhesion strength with the insulating substrate 1 also decreases with temperature and humidity, there is a problem that short circuits may occur even on the surface of the part 13 of the insulating substrate 1.

A portion 13 of the insulating substrate 1 and the resistor 2. To improve the moisture-resistant adhesive strength of epoxy resin 82 and epoxy resin 8. a
It is generally effective to increase the heat distortion temperature of the material to improve moisture resistance. However, since increasing the heat distortion temperature of the epoxy resin also increases its hardness, this method cannot be implemented in the high voltage variable resistor according to the present invention. That is, if the hardness of the epoxy resin is high, when subjected to a temperature shock, the stress generated from the difference in linear expansion coefficient between the porcelain insulating substrate and the epoxy resin will cause cracks in the porcelain insulating substrate.

Also, when integrating the high voltage variable resistor with the FBT, the 14th
As shown in the figure, the surface of the epoxy resin 82 is filled and cured while in contact with the FBT epoxy insulating resin 10. FB
Since the T epoxy insulating resin 10 undergoes curing shrinkage during heating and curing, if the hardness of the epoxy resin 8a is high, stress due to curing shrinkage will be applied to the porcelain insulating substrate 1, causing cracks. In order to reduce the influence of this stress on the porcelain insulating substrate 1, the epoxy resin 89 used in the high voltage variable resistor needs to be flexible, which makes it difficult to increase the heat deformation temperature.

As described above, it is difficult to obtain high moisture resistance and strong adhesive force of the epoxy resin 89 to the insulating substrate 1 and the resistor 2a, and the problem remains that the high voltage resistor has low moisture resistance reliability.

The present invention is intended to solve such conventional problems, and an object of the present invention is to provide a highly reliable high-voltage variable resistor in which the moisture resistance of the high-voltage resistor is improved.

Means for Solving the Problems In order to solve the above problems, the present invention covers the resistor forming surface of the insulating substrate protruding from the frame of the insulating casing with silicone rubber, and covers the opposite surface with flexible epoxy resin. It is coated.

Function: Due to the above-described structure, the adhesive strength between the resistor and the insulating substrate in the high voltage section and the silicone rubber covering the upper surface thereof does not decrease even under high temperature and high humidity conditions, and the high pressure section remains stable even in accelerated humidity resistance life tests. The change in resistance value is extremely small without causing short circuits on the surface of the resistor, and the adhesive strength and interface between the flexible epoxy resin and the FBT epoxy insulating resin that cover the surface of the insulating substrate on which the resistor is not formed are also improved. It also has good leak resistance, and its flexibility relieves stress caused by the difference in coefficient of linear expansion.

Embodiments Hereinafter, regarding the embodiments of the present invention, the same parts as in FIGS. 1 to 6 as well as in FIGS. 12 to 14 are designated by the same numbers (
=f, detailed explanation will be omitted, and the differences will be explained.

Embodiment 1 In FIGS. 1 to 3, 4a is a high potential external connection terminal, 11 is an auxiliary insulating casing, and 12 is a terminal that covers the resistor forming surface of the insulating substrate 1 that protrudes from the frame 5a. 13 is an injection port for the silicone rubber 12.

A frame portion 53 that is integrally molded with the housing 5 and opens in the same direction as the opening of the housing 5 is formed in the insulating housing 5 that is open at one end. An operating knob 6 having a brush 7 provided on the northern part of the frame part 53 is installed in a rotatably held state. Further, an auxiliary insulating casing 11 having an open end is fixed within the casing 5 in contact with the frame portion 5a.

At this time, the step portion formed in the auxiliary insulating casing 11 is formed to be flush with the upper edge of the opening of the frame portion 53. After applying an epoxy resin adhesive to the upper edge of the opening of the frame portion 53 and the upper surface of the staircase portion in the auxiliary insulating housing 11,
A resistor 2 and an electrode 3 are provided on the surface of the electrode 3.
An insulating substrate l made of porcelain to which external connection terminals 4 and 4a are connected and fixed is mounted and sealed with adhesive. A part of the insulating substrate 1 forms a space between it and the casing 5, and a part 23 of the high-voltage resistor 2 is formed on a surface in contact with the space. In addition,
The auxiliary insulating casing 11 is provided with an opening 13 in the same direction as the opening of the insulating casing 5. After filling and hardening the self-adhesive silicone rubber 12 into the space through the opening 13,
A flexible epoxy resin 8 is filled and hardened inside the insulating casing 5 except for the frame portion 5a.

The high-voltage variable resistor of this embodiment is used by being integrated with an FBT, and as shown in FIG. 3, the high-voltage input terminal 43 is connected to the high-voltage output part of the FBT and the
After being fitted and sealed inside, the insulating resin 10 for FBT is filled and hardened together with parts such as a coil constituting the FBT.

FIGS. 9 and 10 are partial sectional views of an FBT coupled with a high-voltage variable resistor according to an embodiment of the present invention. High voltage resistor 2. a and the high voltage resistor mounting portion 1a of the insulating substrate 1
The adhesive force at the interface between the rubber and the silicone rubber 12 is stable even under high temperature and high humidity conditions, and the physical properties of the silicone rubber 12 are stable even under high temperature and high humidity conditions, and unlike conventional epoxy acid anhydrides, No hydrolysis occurs under high temperature and high humidity conditions. Therefore, no electrical short circuit occurs at the interfaces a, c, and d shown in the figure even during the accelerated moisture resistance life test, and the change in the resistance value of the high voltage section resistor 23 is extremely small.

Therefore, the reliability of the high-voltage resistor can be dramatically improved.

Embodiment 2 FIG. 4 shows the configuration of the second embodiment, FIG. 5 shows the planar state before being filled with flexible epoxy resin 8, and FIG. 6 shows the structure of the FBT. This figure shows the configuration of the same embodiment in the case where 113 is an auxiliary insulating casing.

Auxiliary insulation casing 11. As shown in Figure 4, the shape of l is 1
The side wall of the high-voltage resistor mounting portion 13 of the auxiliary insulating casing 11. An independent space 1 between the side wall of the high pressure part of the housing 5
4 can be provided. When integrated into FBT, the independent space 14 is filled with FBT insulating resin 10 and hardened. Therefore, as shown in FIG. 11, the creepage distance of the interface from the high-voltage external connection terminal 4a to the outside of the FBT housing 9 becomes extremely long as a-dB, and is even higher than that in the first embodiment. The reliability of the voltage section can be improved.

Effects of the Invention As is clear from the second embodiment, according to the present invention, the resistor-forming surface of the insulating substrate is made of silicone rubber, and the other surface on which the resistor is not formed is made of flexible epoxy resin. By coating, there is no interfacial leakage even during accelerated humidity resistance life tests under high temperature and high humidity conditions, and the resistance value change of the high voltage section resistor is extremely small, which has the effect of increasing the reliability of the high voltage section. .

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a high-voltage variable resistor according to the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a side sectional view of a flyback transformer incorporating the high-voltage variable resistor according to the present invention, and FIG.
The figure is a side sectional view showing the second embodiment, FIG. 5 is a plan view of the same,
FIG. 6 is a side sectional view of a flyback transformer incorporating the second embodiment, FIG. 7 is a circuit diagram of a flyback transformer showing an example of use of the high voltage variable resistor according to the present invention, and FIG. 8 is a circuit diagram of the flyback transformer according to the present invention. Characteristic diagrams comparing the rate of change in resistance value between the high voltage variable resistor of the example and the conventional high voltage variable resistor, Figures 9-
11 is a partial cross-sectional view of a flyback transformer incorporating the high-voltage variable resistor of the present invention, FIG. 12 is a side sectional view of a conventional high-voltage variable resistor, FIG. 13 is a plan view of the same, and FIG. The figure is a side sectional view of a flyback transformer incorporating a conventional high-voltage variable resistor. 1...Insulating substrate, 2...Resistor, 23
・・・・・・High voltage resistor, 4, 43 external connection terminal,
5... Insulating casing, 52... Frame, 6.
...Operation knob, 8...Flexible epoxy resin, 11,1.1. ,...Auxiliary insulation casing, 1
2...Silicone rubber, 14...Space part. Name of agent: Patent attorney Shigetaka Awano and 1 other person Jyotsu 1 Line 77a Yudo P! Rim Tomita Funeral Map Funeral Map Figure 8 ΔR1hr 5o. Time (/l) Funeral diagram Funeral diagram Figure rA'j Figure 11 Figure 14

Claims (2)

[Claims] (1) An insulating casing that has an operation knob on the bottom and a frame with an opening on the opposite side, and a resistor on one side that covers the frame and protrudes from the frame. an insulating substrate having an external connection terminal housed in the insulating casing; and auxiliary insulation covering a high-voltage resistor provided in the high-voltage section continuously with the resistor on one surface of the insulating substrate. A high-voltage variable device consisting of a casing and an insulating substrate that protrudes from the frame, with the resistor-forming surface covered with silicone rubber, and the other surface where the resistor is not formed with flexible epoxy resin. Resistor. (2) The high voltage variable resistor according to claim 1, further comprising an independent space surrounded by the auxiliary insulating casing, the frame, and the insulating casing.