JPH03280330A - Withstand voltage inspection method for low melting point glass - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for testing the withstand voltage of low melting point glass that seals the panel and funnel of a cathode ray tube.

(Prior Art) Generally, a color cathode ray tube has a bulb 4 in which a panel 1 and a funnel 2 are sealed with a low-melting glass 3, as shown in FIGS. It has a structure in which the parts are tightened with an explosion-proof band 5. Here, the low melting point glass 3 usually has a voltage of 80 kV to 100 kV.
However, if dust or conductive dirt from the manufacturing process remains attached to the sealing part of the panel 1 or the funnel 2 and is welded with the low melting point glass 3, the operation voltage of about 30 kV may be reduced. There were cases where insulation breakdown occurred due to voltage. Therefore, an earth band 6 made of a spring or the like is wrapped around the outer surface of the low melting point glass 3.
is set to ground potential, and a conductor-type anode button 7 formed through the funnel 2 is connected to a power source 8 at 40 to 50 ν.
An inspection method was adopted in which a high voltage was applied to cathode ray tubes with low dielectric strength to cause their dielectric breakdown and then to be removed.

[Problem to be solved by the invention]

However, in the above-described conventional testing method for the withstand voltage characteristics of low-melting point glass, the earth band 6 did not come into close contact with the outer peripheral surface of the bulb 4, as shown in FIG. 11, and a gap 11 was created between the two. . An enlarged sectional view of the structure near this gap is shown in FIG. 12, in which the end of the panel 1 and the end of the funnel 2 are sealed with a low-melting glass 3.

Further, an aluminum vapor deposited film 9 is applied to the inner surface of the panel 1, an internal conductive film 10 is applied to the inner surface of the funnel 2, and a high voltage power source 8 is applied to the internal conductive film 10 via an anode button 7.
There is a gap 11 between the outer surface of the low melting point glass 3 and the earth band 6 at the ground potential.Furthermore, the inner surface of the low melting point glass 3 has a getter ll! 1
12 is scattered, so the internal conductivity l! A high voltage is applied via 10. , El is the electric field between the outer surface of the low melting point glass 3 and the earth band 6, and E is the electric field applied to the low melting point glass 3. In this situation, the high voltage applied from the power source 8 is applied to the low melting point glass 3 and the gap 11. Since the dielectric constant of the low melting point glass 3 is about 7,
For example, if the radial length of the low melting point glass 3 is equal to the radial length of the gap 11, only 1/7 of the applied voltage will be applied to the cross section of the low melting point glass 3, which will be lower than the operating voltage of the cathode ray tube. The purpose of the withstand voltage test, which was to remove in advance the cathode ray tube whose dielectric strength of the low melting point glass 3 was weak, could not be achieved because the voltage was much lower. For this reason,
When used at a customer's site, dielectric breakdown of the low melting point glass 3 caused damage to the cathode ray tube circuit and sometimes caused a fire.

This invention was made to solve the above-mentioned problems, and provides a method for testing the withstand voltage of low-melting point glass, which can reliably detect and remove cathode ray tubes with low dielectric strength of low-melting point glass. [Means for Solving the Problems] A method for testing low melting point glass withstand voltage according to the claims of the present invention includes applying a high voltage to a conductive film formed on the inner surface of a funnel and , an earth potential earth band is provided on the outer circumferential surface of the low-melting point glass in a shape that allows corona discharge to occur.

The method for testing low melting point glass withstand voltage according to claim 2 of the present invention involves applying a high voltage to a conductive film formed on the inner surface of a funnel, and applying a high frequency high voltage from a Tesler coil to the outer surface of the low melting point glass. 3 The method for testing low melting point glass withstand voltage according to claim 3 of the present invention is to apply a high voltage to a conductive film formed on the inner surface of a funnel, and to apply a conductive film to the outer surface of the low melting point glass. A band is provided, and a high frequency and high voltage from a Tesler coil is applied to this conductive band.

The withstand voltage test method for low melting point glass according to claim 4 of the present invention operates a cathode ray tube, applies a high voltage to the conductive film of the funnel, and applies a high frequency high voltage from a Tesler coil to the outer surface of the low melting point glass. 8 [Function] In claim I of the present invention, an earth band is provided around the outer periphery of the low melting point glass, and the earth band has a shape that allows corona discharge to settle therein and has a shape that allows corona discharge to take place, and has a shape that allows corona discharge to occur easily. A large electric field is applied between them, causing corona discharge. For this reason, the outer surface of the low melting point glass is charged and this portion becomes a ground potential, and a large voltage is applied between the inner and outer surfaces of the low melting point glass, making dielectric breakdown more likely to occur.

In claim 2 of the invention, a high voltage is applied to the inner surface of the low melting point glass, and a high frequency high voltage from a Tesla coil is applied to the outer surface of the low melting point glass, so that a high voltage is applied to the outer surface of the low melting point glass. A large voltage is applied to the , making dielectric breakdown more likely to occur.

In claim 3 of the present invention, a high voltage is applied to the inner surface of the low melting point glass, and a high frequency high voltage from a Tesler coil is applied to the outer surface of the low melting point glass via a conductive band. A large voltage is applied between the inner and outer surfaces of the melting point glass.

In claim 4 of the present invention, a high voltage is applied to the inner surface of the low melting point glass, and a high frequency high voltage is applied from a Tesla coil to the outer surface of the low melting point glass, and between the inner and outer surfaces of the low melting point glass. When a large voltage is applied, dielectric breakdown is likely to occur in the low melting point glass (also, the X-rays emitted from the cathode ray tube ionize the gas in the bubbles in the low melting point glass, making it easier to cause dielectric breakdown in the -layer). .

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1st
FIG. 2 is a front view and a plan view of a cathode ray tube for explaining the withstand voltage test method for low melting point glass according to the first embodiment of the present invention. The earth band 13 is provided with a shape in which corona discharge is likely to occur, that is, a shape with many sharp portions 13a.

Gaps 11 are formed here and there between the low melting point glass 3 and the earth band 13. FIG. 3 is an enlarged cross-sectional view of the main part of FIG. 1, in which high voltage is applied from the DC high-voltage power source 8 via the anode button 7 to the conductors 11!10 formed on the inner surface of the funnel 2, as in the conventional case. At this time, since the low melting point glass 3 has a large dielectric constant, a large electric field is applied to the gap 11. For this reason, the sharp portion 13a of the earth band 13
A corona discharge occurs, and the outer surface of the low melting point glass 3 is charged, and this portion becomes a ground potential. Therefore, a high voltage from the power source 8 is applied between the inner and outer surfaces of the low melting point glass 3, causing dielectric breakdown of the low melting point glass 3 having a low level of dielectric strength. can be removed in advance.

In addition, in the first embodiment described above, the earth band 1
Although sharp portions 13a were provided on the inner and outer surfaces of 3,
The sharp portion 13a only needs to be on the inner surface, and should not be on the outer surface for handling reasons.Also, since the sharp portion 13a comes into contact with the surfaces of the low melting point glass 3, the panel 1, and the funnel 2, It is best to use soft metal or conductive plastic to prevent scratches.

FIG. 4 and FIG. 5 are a front view and a plan view of a cathode ray tube for explaining the withstand voltage test method for low melting point glass according to the second embodiment of the present invention. A large number of Tesler coils 14 are provided close to the outer peripheral surface of the low melting point glass 3, and a high frequency and high voltage is applied from the Tesler coils 14 toward the low melting point glass 3. 6 is an enlarged sectional view of the main part of FIG. 4, and shows the conductive film l on the inner surface of the funnel 2.
30 to 40 from the power supply 8 via the anode button 7 to O.
A DC high voltage of kV is applied, and this voltage is applied to the getter film 12.
is also applied to the inner surface of the low melting point glass 3 on which is formed.

On the other hand, on the outer surface of the low melting point glass 3, a Tesla coil 14 is provided.
During this time, corona discharge 1 is generated by applying high frequency and high voltage from
5 is generated, and the low melting point glass 3 is charged with a negative or positive charge. Therefore, the DC high voltage from the power supply 8 and the high frequency high voltage from the Tesler coil 14 are superimposed and applied between the inner and outer surfaces of the low melting point glass 3, and the peak value increases accordingly, resulting in a low level of dielectric strength. The low melting point glass 3 is dielectrically broken down, and the cathode ray tube using this low melting point glass 3 is removed. Further, since the dielectric strength of the low melting point glass 3, which is a solid insulator, is weakened against high frequency voltage, negative layer dielectric breakdown occurs and increases. Furthermore, in the case of a small cathode ray tube, the distance between the anode button 7 and the explosion-proof band 5 is narrow, and creeping discharge may occur between the anode button 7 and the explosion-proof band 5 through the outer surface of the funnel 2, especially in a humid environment. However, it is not possible to apply a very high voltage to the anode button 7, and a large dielectric breakdown ability cannot be obtained. Even in such a case, a large dielectric breakdown capability can be obtained by increasing the high frequency and high voltage from the Tesler coil 14, and a highly reliable withstand voltage testing method can be obtained.

FIG. 7 is a plan view of a cathode ray tube for explaining a method for testing low melting point glass withstand voltage according to a third embodiment of the present invention. In this third embodiment, a high voltage is applied to the conductive film 10 of low melting point glass, and a conductive band 16 is provided close to the outer surface of the low melting point glass. One Tesla coil 14 in close proximity
is provided, and a high frequency high voltage is applied from the Tesler coil 14 to the conductive band 16. The conductive band 16 must be kept away from ground potential. The conductive band 16 to which a high frequency and high voltage is applied generates a corona discharge 15 between the conductive band 16 and the low melting point glass 3, and a large voltage is applied between the inner and outer surfaces of the low melting point glass 3, making dielectric breakdown likely to occur. Further, by providing only one Tesler coil 14, the corona discharge 15 can be generated uniformly over the entire circumference of the outer surface of the low melting point glass 3, which is efficient.

FIG. 8 shows a fourth embodiment of the present invention. In this embodiment, the conductive band 16 is divided into four parts, each of which is provided with a Tesler coil 14, and the operation and effect are similar to those of the third embodiment. be.

FIG. 9 shows a fifth embodiment of the present invention, in which a voltage is applied from a cathode ray tube circuit 17 to each electrode of the pulp 4 through a socket 18, and at the same time the deflection coil 1
A high frequency voltage is applied to 9 to operate the cathode ray tube. In this state, as in the first embodiment, a high DC voltage is applied to the conductive film 10 formed on the inner surface of the funnel 2, and a high frequency signal is applied from the Tesler coil 14 disposed close to the outer surface of the low melting point glass 3. Apply high voltage. A large voltage is applied between the inner and outer surfaces of the low melting point glass 3, making it easy to cause dielectric breakdown, and X-rays are emitted from inside the cathode ray tube, ionizing the gas in the bubbles in the low melting point glass 3, causing the -layer to ionize. Dielectric breakdown is more likely to occur.

[Effects of the Invention] As described above, according to the present invention, since the earth band provided on the outer surface of the low melting point glass is shaped so that corona discharge is likely to occur, corona discharge occurs between the low melting point glass and the earth band. , the outer surface of the low melting point glass is at ground potential, and a large voltage is applied between the inner and outer surfaces of the low melting point glass, making it easy to cause dielectric breakdown. Therefore, cathode ray tubes made of low melting point glass with low dielectric strength can be detected and removed, and the occurrence of defects during operation at the customer's site can be significantly reduced.

Further, according to the present invention, a high frequency and high voltage is applied to the outer surface of the low melting point glass from the Tesla coil, and a large voltage can be applied between the inner and outer surfaces of the low melting point glass.
It is possible to cause more dielectric breakdown in the container, and it is possible to suppress the occurrence of defects during use. Furthermore, by increasing the high frequency and high voltage from the Tesler coil, the voltage applied to the inner surface of the funnel can be lowered, and creeping discharge in the funnel can be prevented and the reliability can be improved.

Furthermore, by providing a conductive band between the low melting point glass and the Tesler coil, corona discharge can be generated uniformly around the entire circumference of the low melting point glass with a small number of Tesler bands, improving efficiency. . In addition, by applying high frequency and high voltage from the Tesler coil to the low melting point glass without operating the cathode ray tube,
When the radiation is emitted, the gas within the bubbles of the low-melting point glass is ionized, making it easy to cause dielectric breakdown in the -layer.

[Brief explanation of drawings]

1 to 3 are a front view, a plan view, and an enlarged cross-sectional view of essential parts of a cathode ray tube showing a withstand voltage testing method according to a first embodiment of the invention, and FIGS. A front view, a plan view, and an enlarged sectional view of a cathode ray tube showing the withstand voltage testing method according to the second embodiment, and FIGS. 7 to 9 show the withstand voltage testing method according to the third to fifth embodiments of the present invention. FIGS. 10 to 12 are a front view, a plan view, and an enlarged sectional view of essential parts of a cathode ray tube showing a conventional method. 1... Panel, 2... Funnel, 3... Low melting point glass, 4... Bulb, 7... Anode button, 8
...High voltage power supply, lO... Conductive film, I3... Earth band, 14... Tesler coil, 6... Conductive band. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (4)

[Claims] (1) In a cathode ray tube in which the panel and funnel are sealed with low-melting glass, a high voltage is applied to the conductive film formed on the inner surface of the funnel, and the outer peripheral surface of the low-melting glass is shaped so that corona discharge is likely to occur. A method for testing low melting point glass withstand voltage, which is characterized by providing an earth band at earth potential. (2) In a cathode ray tube in which the panel and funnel are sealed with low melting point glass, a high voltage is applied to the conductive film formed on the inner surface of the funnel, and a high frequency high voltage from a Tesler coil is applied to the outer surface of the low melting point glass. A method for testing low melting point glass withstand voltage, which is characterized by applying voltage. (3) In a cathode ray tube in which the panel and funnel are sealed with low-melting glass, a high voltage is applied to the conductive film formed on the inner surface of the funnel, and a conductive band is provided on the outer circumferential surface of the low-melting glass. A method for testing low melting point glass withstand voltage, which is characterized by applying high frequency and high voltage from a Tesler coil to the sex band. (4) In a cathode ray tube in which the panel and funnel are sealed with low-melting glass, a voltage is applied to the cathode ray tube to operate the cathode ray tube, and a high voltage is applied to a conductive film formed on the inner surface of the funnel, and A method for testing low melting point glass withstand voltage, which is characterized by applying high frequency and high voltage from a Tesler coil to the outer surface of the low melting point glass.