JP2000277015A - Cleaning method of color cathode ray tube and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a neck crack in a knocking process. SOLUTION: An electrode 31 is inserted in an opening of a neck 4 of a funnel 1, wherein the funnel 1 has an inner conductive film 6 formed on the inner surface and a bulb 8 has a panel 2 having a phosphor film 7 on the inner surface sealed to the funnel 1 with frit 3. Potentials which make the electrode 31 positive and a positive electrode terminal 5 of the funnel 1 negative are given, and discharge is generated between the electrode 31 and the inner conductive film 6 so as to clean an end of the inner conductive film 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for cleaning a color cathode ray tube, and more particularly to a method for cleaning an internal conductive film formed on an inner surface of a funnel and a method for cleaning an electron gun sealed in a bulb. .

[0002]

2. Description of the Related Art A color cathode ray tube is manufactured by a process shown in FIG. A funnel 1 having an inner conductive film formed on the inner surface and a panel 2 having a fluorescent film formed on the inner surface are frit-sealed 3 with low-melting glass. Next, a frit-sealed portion inspection 20 of the insulating state of the frit-sealed portion is performed. This frit sealing portion inspection 20 is performed, for example,
As disclosed in Japanese Patent No. 50580, a high voltage is applied between the internal conductive film and the frit sealing portion to detect an insulation defect in the frit sealing portion.

Next, an electron gun 1 is placed inside the neck of the funnel 1.
0 is inserted to seal 21. After that, the chamber is evacuated 22 to perform a sealing operation. After this vacuum sealing is completed, the electron gun 1
Knocking 23 is performed by applying a DC or pulsed high voltage to each electrode for the purpose of removing minute projections of the zero grid electrode. Thereafter, aging 24 is performed.

[0004] As shown in FIG.
1, a first grid electrode 12, a second grid electrode 13, a third grid electrode 14, and an anode 15. As the knocking 23 described above, a method called partial pressure knocking is widely used for the purpose of cleaning the third grid electrode 14. Normally, a predetermined voltage is applied to the third grid electrode 14 at a voltage division ratio of the resistors RI and R2. As a result, a discharge is generated between the minute projections of the second grid electrode 13 and the third grid electrode 14, and the minute projections are evaporated and removed by the heat generated during the discharge.

[0005]

Conventionally, knocking 23
There was a problem that cracks occurred in the neck during the process. The inventors of the present application have conducted various investigations on the cause, and as a result, it has been found that the end of the internal conductive film has an influence.

[0006] The knocking 23 step is performed in the range of 40 to 60 in order to effectively remove minute projections of the grid electrode.
A high voltage of KV is applied. As a result, if the end of the internal conductive film is roughened and a minute protrusion is present at the end, electric field concentration occurs at the end of the internal conductive film, and a neck through current flows from the inner surface of the neck to the outer surface, Sometimes neck cracks occur. For this reason, the upper limit of the voltage value to be applied is restricted and the application time is limited. In order to obtain sufficient withstand voltage characteristics, an application process including a cooling period is required, and the equipment becomes large and expensive. was there.

In the knocking 23 step, the neck cracks near the end of the internal conductive film mainly because the second grid electrode 13 is insufficiently cleaned, and the voltage applied to the anode 15 is reduced. This is because it is set high.
That is, when a discharge occurs between the second grid electrode 13 and the third grid electrode 14 in the knocking 23 step, the potential difference between the third grid electrode 14 and the anode 15 greatly increases. This potential rise causes a rise in the potential of the inner and outer surfaces of the neck, causing a current to flow through the neck and leading to cracks.
In addition, due to insufficient cleaning of the second grid electrode 13,
Since the voltage applied to the anode 15 is set high, the probability of occurrence of cracks increases.

It is an object of the present invention to provide a method and an apparatus for cleaning a color CRT which can prevent neck cracks in a knocking process.

[0009]

A first means of the present invention for solving the above-mentioned problems is to frit seal a funnel having an inner conductive film formed on an inner surface or a panel having a fluorescent film formed on an inner surface to the funnel. In the valve, an electrode is inserted into the neck opening of the funnel, and the electrode is
A negative potential is applied to the anode terminal of the funnel to generate a discharge between the electrode and the internal conductive film, thereby cleaning an end of the internal conductive film.

[0010] A second means of the present invention for solving the above-mentioned problem is that a valve in which a funnel having an internal conductive film formed on an inner surface thereof and a panel having a fluorescent film formed on the inner surface thereof are frit-sealed is a neck opening of the valve. An electrode is inserted into the portion, and a current detector for measuring a current flowing through the frit sealing portion is provided, a pulse having a phase difference of 180 degrees is applied to the electrode and the anode terminal of the bulb, and a pulse potential is applied to the electrode. When a discharge is generated between the electrode and the internal conductive film, an end of the internal conductive film is cleaned, and when a pulse potential is applied to the anode terminal, a current flowing through the current detector is measured. Thus, the frit sealing portion insulation defect is detected.

A third means of the present invention for solving the above-mentioned problem is to provide a color cathode ray tube in which an electron gun is sealed in a bulb, connect two circuits in parallel with a resistor and a capacitor in series, and connect one end to a power supply and one end. Connected to the anode of the electron gun, the other end is grounded, the voltage dividing point of the series circuit is connected to the third grid electrode, knocking is performed by applying a low voltage to the anode, and the second and third grid electrodes are connected. It is characterized by being cleaned.

[0012]

FIG. 1 shows a first embodiment of the present invention.
This will be described below. The electrode 31 is connected to the positive potential of the high voltage power supply 30, and the anode contact terminal 33 is connected to the negative potential of the high voltage power supply 30 via the switch 32. Then, the electrode 31 is inserted into the opening of the neck 4 of the funnel 1 and the anode contact terminal 33 is inserted.
To the anode terminal 5 to turn on the switch 32.
If a defect such as a protrusion is present at the end of the internal conductive film 6 formed on the inner surface of the funnel 1, a discharge occurs between the electrode 31 and the end of the internal conductive film 6, causing a problem such as a protrusion at the end. The location evaporates and is removed.

As described above, since the end of the internal conductive film 6 is smoothed and cleaned, even if a high voltage is applied to the electron gun in a knocking step in a later step, the end of the internal conductive film 6 is not removed. Electric field concentration does not occur, and neck cracks are prevented.

The cleaning of the end of the internal conductive film 6 is performed by the method shown in FIG.
1A, a funnel 1 having an internal conductive film 6 formed on the inner surface, or a funnel 1 having the internal conductive film 6 formed on the inner surface and a fluorescent film 7 formed on the inner surface, as shown in FIG. 1B. In the valve 8 in which the flit-sealed panel 2 is frit-sealed 3, it can be appropriately selected and implemented.

FIGS. 2 and 3 show a second embodiment of the present invention. This embodiment shows an example in which the present invention is applied to the frit sealing portion inspection 20 shown in FIG. As shown in FIG.
The electrode 31 and the anode contact terminal 33 are connected to the positive potential of the high voltage power supply 30 via a first switch 40 and are grounded via a second switch 41. Here, the first and second changeover switches 4
0 and 41 are interlocking switches, and when the first changeover switch 40 is connected to the electrode 31, the second changeover switch 41 is connected to the anode contact terminal 33,
When the first switch 40 is connected to the anode contact terminal 33, the second switch 41
Connected to 1. In addition, the current detection terminal 42 contacts the outer periphery of the frit sealing portion 3 as in the prior art, and the current detection terminal 4
2 is connected to an ammeter 44 via a diode 43.

Therefore, by switching the first and second changeover switches 40 and 41, as shown in FIG. 3, the electrode 31 and the anode terminal 5 have a phase of 180 degrees, respectively.
Pulse-like high voltages different in degree are applied. Therefore, when a high voltage is applied to the electrode 31, the end of the internal conductive film 6 is cleaned in the same manner as in the first embodiment (FIG. 1). When a high voltage is applied to the anode terminal 5, the current flowing through the frit seal 3 from the anode terminal 5 can be measured by the ammeter 44 as in the conventional case, and the insulation test of the frit seal 3 can be performed.

FIG. 4 shows a third embodiment of the present invention.
In each of the above embodiments, the edge of the internal conductive film 6 is cleaned to prevent the neck 4 from cracking in the knocking step. In the present embodiment, the voltage applied to the anode 15 in the knocking step is kept low, so that the desired knocking effect can be obtained.

As shown in FIG. 4, the resistors RI and R2 shown in FIG.
, Capacitors CI and C2 were added in parallel. That is, a circuit in which the capacitor C1 is connected in parallel to the resistor R1 and the resistor R1
2 and a circuit in which a capacitor C2 is connected in parallel is connected in series. Then, the ends of the resistor R1 and the capacitor C1 are connected to the anode 15 and the power supply 16, and the resistor R2 and the capacitor C2 are connected.
Ground the end of the Further, the voltage dividing point of the series circuit was connected to the third grid electrode 14.

The values of the resistors R1 and R2 and the capacitors C1 and C2 are set as shown in Equation 1. Here, R1 · C1 and R
The ratio of 2 · C2 may be in the range of 1: 1 or 1: 2-3.

[Equation 1] R1 · C1 ≒ R2 · C2

The resistors R1 and R
By setting the capacitors 2 and the capacitors C1 and C2, even when a discharge occurs, a sharp increase in the potential between the third grid electrode 14 and the anode 15 can be prevented, so that a crack in the neck 4 can be prevented.

FIG. 5 shows a fourth embodiment of the present invention.
This embodiment is similar to the third embodiment (in the case of FIG. 4).
This is performed when the cleaning of the second grid electrode 13 is insufficient, and the neck 4 can be prevented from cracking by realizing the cleaning of the second grid electrode 13 at a relatively low voltage. Cathode 1
1 is connected to a variable power supply 51, and the first, second and third grid electrodes 12, 13 and 14 are connected to power supplies 52, 53 and 54, respectively. A voltage of 1 kV is applied to the second grid electrode 13, a positive bias is applied to the first grid electrode 12, and several mA
Of the second grid electrode 13
To clean. The electrons that have passed through the second grid electrode 13 give a negative potential to the third grid electrode 14. The purpose of this is to generate gas in the tube due to floating electrons generated at the anode 15 and the like.

[0022]

According to the first and second means of the present invention,
The end of the internal conductive film is cleaned, and a neck crack in the knocking process can be prevented. Further, according to the third means, a sharp increase in potential between the anode and the third grid electrode can be prevented, so that neck cracks can be prevented.

[Brief description of the drawings]

FIGS. 1A and 1B show a method for cleaning a color cathode ray tube according to a first embodiment of the present invention, wherein FIG. 1A is an explanatory diagram before panel sealing and FIG. 1B is an explanatory diagram after panel sealing.

FIG. 2 is an explanatory diagram showing a method for cleaning a color CRT according to a second embodiment of the present invention.

FIG. 3 is a pulse voltage diagram applied to the electrode and anode contact terminal of FIG. 2;

FIG. 4 is a circuit diagram showing a color cathode ray tube cleaning apparatus according to a third embodiment of the present invention.

FIG. 5 is a circuit diagram showing a color cathode ray tube cleaning apparatus according to a fourth embodiment of the present invention.

FIG. 6 is a flowchart showing the steps of manufacturing a color cathode ray tube.

FIG. 7 is an explanatory view of a conventional knocking device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Funnel 2 Panel 3 Frit sealing 4 Neck 5 Anode terminal 6 Internal conductive film 7 Fluorescent film 8 Bulb 10 Electron gun 13 Second grid electrode 14 Third grid electrode 15 Anode 30 High voltage power supply 31 Electrode 33 Anode contact terminal 40 First Changeover switch 41 Second changeover switch 42 Current detection terminal 44 Ammeter R1, R2 Resistance C1, C2 Capacitor

Claims (3)

[Claims] 1. A bulb in which a funnel having an inner conductive film formed on the inner surface or a panel having a fluorescent film formed on the inner surface is frit-sealed to the funnel, an electrode is inserted into a neck opening of the funnel, and the electrode is fixed to the front. Applying a negative potential to the anode terminal of the funnel to generate a discharge between the electrode and the internal conductive film, thereby cleaning an end of the internal conductive film. 2. A bulb in which a funnel having an internal conductive film formed on the inner surface and a panel having a fluorescent film formed on the inner surface are frit-sealed, wherein an electrode is inserted into a neck opening of the bulb, and the frit-sealed portion is provided. A current detector for measuring the flowing current is provided, and 180
When a pulse having a different phase is applied and a pulse potential is applied to the electrode, a discharge occurs between the electrode and the internal conductive film to clean the end of the internal conductive film, and a pulse potential is applied to the anode terminal. A method for cleaning a color cathode ray tube, comprising: detecting an insulation defect in a frit sealing portion by measuring a current flowing through the current detector when the voltage is applied. 3. A color cathode ray tube in which an electron gun is sealed in a bulb, two circuits each having a resistor and a capacitor connected in parallel are connected in series, and one end is connected to a power supply and an anode of the electron gun.
The other end is grounded, the voltage dividing point of the series circuit is connected to the third grid electrode, knocking is performed by applying a low voltage to the anode, and the second and third grid electrodes are cleaned. Cleaner for color CRT.