JP2737617B2 - High voltage leak detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage leak detector, and more particularly, to a high-voltage leak detector for determining the quality of insulation at a frit seal portion for sealing a funnel of a bulb and a face panel in the manufacture of a cathode ray tube. The present invention relates to a voltage leak detection device.

[0002]

2. Description of the Related Art For example, a bulb 1 made of lead glass or the like used for a cathode ray tube comprises a trumpet-shaped funnel 2 integrally having a neck 3 and a substantially flat face panel 4 as shown in FIG. A structure joined by sealing with insulating frit glass is common. On the other hand, an inner conductive film 6 such as graphite is formed on the inner surface of the valve 1 from the neck 3 to the funnel 2 to the vicinity of the frit seal portion 5.
An anode button 7 is provided, which is electrically connected to the outside and led to the outside.

The above-mentioned interior conductive film 6 is electrically connected to a high-voltage electrode of an electron gun which is finally sealed in the neck 3 at the neck side end of the funnel 2 and has a frit seal at the face panel side end. In the vicinity of the portion 5, it is electrically connected to a metal back film extending from the inner surface of the face panel 4 by a contact pin (not shown), and is applied with a high voltage from the anode button 7 via the inner conductive film 6 to the electron gun. Are maintained at a high voltage state.

On the other hand, it is necessary that the frit seal portion 5 has a sufficient insulating property. For example, when the funnel 2 and the face panel 4 are sealed with frit glass, the end face of the funnel 2 or the face panel 4 is closed. If the frit glass is dirty or bubbles are generated in the frit glass, when the high voltage is applied by the actual use of the cathode ray tube, the insulation at the frit seal portion 5 cannot be sufficiently secured, and the high voltage is applied inside and outside the bulb 1. This is extremely dangerous because dielectric breakdown occurs due to leakage. Therefore, in the manufacture of cathode ray tubes,
It must be checked beforehand whether or not the insulation at the frit seal portion 5 is ensured.

Therefore, in the manufacturing process of the cathode ray tube, after the interior conductive film 6 is formed on the inner surface of the bulb 1, the frit seal portion 5 is inspected by the following high voltage leak detector. As shown in FIGS. 3 and 4, this high-voltage leak detector surrounds a rod-shaped contact pin 9 which contacts an anode button 7 of a funnel 2 and receives a high voltage from a high-voltage power supply 8. Electrode 11 made of an umbrella-shaped rubber insulating cap 10 that adheres to the outer surface of the funnel 2 while being supported
And a frame-shaped detection electrode 13 to which a measuring device 12 for detecting the presence or absence of a leak current is connected, which is fitted to the frit seal portion 5 and comes into contact therewith.

The detection of high voltage leakage is performed as follows. That is, a high voltage is applied from the high-voltage power supply 8 to the interior conductive film 6 through the contact pins 9 of the contact electrodes 11 and the anode buttons 7 that are in contact with the contact pins 9. By applying the high voltage, the measuring device 12 detects the amount of leakage current flowing from the inner conductive film 6 on the inner surface of the funnel 2 to the frit seal portion 5 and leaking through the detecting electrode 13. If the leak current is equal to or higher than a predetermined level, the insulation at the frit seal portion 5 is not ensured, and the valve 1 becomes a defective product. And the bulb 1 becomes a good product.

[0007]

However, the detection of leak current by the above-described high-voltage leak detector has the following problems. That is, when the contact electrode 11 is mounted, the insulating cap 10 is elastically deformed by a cylinder (not shown) so that the peripheral portion of the insulating cap 10 is securely adhered to the outer surface of the funnel 2. To press.

However, the pressing of the insulating cap 10 by the cylinder is performed only when the contact electrode 11 is mounted prior to the application of the high voltage, and the outer surface of the funnel 2 remains lead glass as shown in the enlarged portion of FIG. Due to the rough surface state, the adhesion of the peripheral portion of the insulating cap 10 is low only by pressing with the cylinder only at the time of mounting before applying a high voltage. As a result, a creeping leak phenomenon in which a leak current flows to the detection electrode 13 along the outer surface of the funnel 2 and a phenomenon in which a discharge current flows between the contact pin 9 and the detection electrode 13 due to the application of a high voltage by the contact pin 9. Occur.

When such a phenomenon occurs, the detection electrode 1
The leak current detected by the measuring device 12 by the measuring device 3 includes not only a leak current flowing through the inner conductive film 6 on the inner surface of the funnel 2 but also a leak current and a discharge current due to a creeping leak on the outer surface of the funnel 2. Become.
Then, almost no leak current flows through the interior conductive film 6 on the inner surface of the funnel 2 and is detected through the frit seal portion 5, and even if the valve 1 is to be a non-defective product, it is caused by the creeping leak on the outer surface of the funnel 2. When a leak current or a discharge current flows and is detected, the valve 1
Is erroneously determined as a defective product, and the reliability of high voltage leak detection is reduced, and the yield of the product is also reduced.

Accordingly, the present invention has been proposed in view of the above-mentioned problems, and an object of the present invention is to provide a high-voltage leak detection device capable of preventing erroneous determination in detecting a high-voltage leak at a frit seal portion. It is to provide a device.

[0011]

As a technical means for achieving the above-mentioned object, the present invention relates to a contact pin to which a high voltage from a high-voltage power supply is applied in contact with an anode button of a funnel of a valve, and a contact pin therefor. A contact electrode consisting of an insulating cap that is in close contact with the outer surface of the funnel while supporting the contact pin so as to surround it, and a measuring instrument that detects the presence or absence of leak current that is in contact with the frit seal between the funnel and the face panel are connected In the high-voltage leak detection device including the detection electrode, the contact electrode is provided with a vacuum suction means for bringing an internal space surrounding the contact pin into a negative pressure state with an insulating cap.

It is desirable that the contact pin be resiliently urged in the protruding direction and supported by the insulating cap so as to be retractable, or its tip portion is made of an elastically deformable member. .

[0013]

In the high-voltage leak detecting apparatus according to the present invention, the vacuum suction means for attaching the contact electrode to the internal space surrounding the contact pin with the insulating cap is provided with a negative pressure state. If the internal space of the insulating cap is set to a negative pressure state by vacuum evacuation, even when high voltage is applied, the peripheral edge of the insulating cap that contacts the outer surface of the funnel is strongly pressed against the outer surface of the funnel at atmospheric pressure. The adhesion between the periphery of the insulating cap and the outer surface of the funnel has been greatly improved.
Creepage leakage and discharge current that reach the detection electrode from the contact pin via the funnel outer surface can be reliably prevented.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a high voltage leak detecting device according to the present invention will be described with reference to FIGS. Note that the same or corresponding parts as those in FIGS. 3 and 4 are denoted by the same reference numerals, and redundant description is omitted.

A feature of the present invention resides in that, as shown in FIG. 1, a vacuum suction means 24 is provided in the contact electrode 21 to bring the internal space m surrounding the contact pin 23 with the insulating cap 22 into a negative pressure state. . Specifically, as shown in the figure, a tubular member 25 is penetrated and fixed in the vicinity of the contact pin supporting portion of the insulating cap 22, and connected to a vacuum device 26 such as a vacuum pump on the outside of the tubular member 25. The flexible tube 27 is attached.

On the other hand, the contact pin 23 has a structure in which the contact pin 23 is resiliently urged in the projecting direction and is supported by the insulating cap 22 so as to be retractable. Specifically, a hole 28 in which the contact pin 23 is penetrated through the central portion of the insulating cap 22
And a bellows-like cylindrical elastic member 29 surrounding the contact pin 23 is interposed between the periphery of the hole and the tip of the contact pin 23, and the contact pin 23 is protruded by the elastic member 29. The structure is such that it can be retracted while being elastically biased in the direction.
2 to hermetically separate the internal space m from the outside. The high-voltage power supply 8 is connected to the base end of the contact pin 23 as in the prior art.
Are electrically connected.

In the high-voltage leak detecting device provided with the contact electrode 21 having the above-described structure, the detection of the high-voltage leak is started by mounting the contact electrode 21 on the funnel 2 of the bulb 1 in the following manner.

First, after the contact pin 23 of the contact electrode 21 is aligned with the anode button 7 of the funnel 2, the periphery of the insulating cap 22 is brought into contact with the outer surface of the funnel 2. In this state, the flexible tube 2 is evacuated by a vacuum device 26 such as a vacuum pump.
The internal space m of the insulating cap 22 is set to a negative pressure state via the tubular member 7 and the tubular member 25. When the internal space m of the insulating cap 22 is in a negative pressure state, the insulating cap 2
2 is pressed against the outer surface of the funnel 2 by the atmospheric pressure, and is forcibly brought into close contact.

Thus, even when a high voltage is applied to the contact pins 23 from the high voltage power supply 8, the insulating cap 2 is always
2 is strongly pressed against the outer surface of the funnel 2, so that it is possible to reliably prevent a creeping leak or a discharge current from reaching the detection electrode 13 from the contact pin 23 through the outer surface of the funnel 2. Therefore, the contact pin 23
Flows through the interior conductive film 6 on the inner surface of the funnel 2 through the anode button 7, and the quality of the frit seal portion 5 due to the high voltage leak can be determined based only on the leak current detected through the frit seal portion 5. There will be no misjudgment.

On the other hand, since the internal space m of the insulating cap 22 is in a negative pressure state as described above,
Is pressed strongly against the anode button 7 of the funnel 2. At this time, the contact pin 23 has a structure capable of retreating against the insulating cap 22 against the elastic force of the elastic member 29. So contact pin 2
A favorable contact state of the contact pin 23 with the anode button 7 is ensured without damaging the anode button 7 by reducing the force of pressing the tip of the anode button 3 against the anode button 7.

As means for ensuring a good contact state of the contact pin 23 with the anode button 7, besides the above-mentioned structure, the tip of the contact pin can be made of an elastically deformable member. As shown in FIG. 2, a metal fiber molded product 30 may be fixed to the tip of the contact pin 23 '. Therefore, when the contact pin 23 'contacts the anode button 7, the molded product 30 at the tip of the contact pin 23' is elastically deformed, so that the pressing force is reduced and a good contact state is obtained.

Although the contact pin 23 shown in FIG. 1 is movable with respect to the insulating cap 22 as described above, the present invention is not limited to this, and the contact pin 23 shown in FIG. ', A structure fixed to the insulating cap 22 may be used as in the conventional case.

[0023]

According to the high voltage leak detecting device of the present invention, the internal space surrounding the contact pins with the insulating cap is forcibly brought into the negative pressure state by the vacuum suction means, so that the high voltage leak detecting device can be used. Even when a high voltage is applied, sufficient adhesion between the peripheral portion of the insulating cap and the outer surface of the funnel can always be ensured. As a result, creeping leaks and discharge currents generated on the outer surface of the funnel can be reliably prevented, and erroneous determination in detecting high voltage leaks at the frit seal portion can be prevented beforehand, so that high voltage leak detection reliability and product yield Is greatly improved.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a contact electrode showing an embodiment of a high-voltage leak detection device according to the present invention.

FIG. 2 is an enlarged view of a contact pin showing another embodiment of the present invention.

FIG. 3 is a diagram for explaining high voltage leak detection in the manufacture of a cathode ray tube, and is a schematic configuration diagram of a valve and a high voltage leak detection device.

FIG. 4 is an enlarged sectional view of a contact electrode showing a conventional example of a high-voltage leak detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Valve 2 Funnel 4 Face panel 5 Frit seal part 7 Anode button 8 High voltage power supply 12 Measuring instrument 13 Detection electrode 21 Contact electrode 22 Insulating cap 23 Contact pin 24 Vacuum suction means m Internal space

Claims (2)

(57) [Claims] A contact comprising a contact pin to which a high voltage from a high-voltage power supply is applied in contact with an anode button of a funnel of a valve and an insulating cap which is in close contact with the outer surface of the funnel while surrounding the contact pin. In a high voltage leak detection device comprising an electrode and a detection electrode connected to a frit seal portion of a funnel and a face panel and connected to a measuring device for detecting the presence or absence of a leak current, the contact electrode is an insulating cap. Vacuum suction means for bringing the internal space surrounding the contact pin into a negative pressure state is provided, and the contact pin is
It can be retracted while being elastically biased in the projecting direction.
A high voltage leak detection device supported by an edge cap . 2. The contact pin has a tip portion
2. A structure comprising a member capable of sexual deformation.
The high voltage leak detection device according to the above.