JPH02291640A - Withstand voltage treatment of cathode-ray tube - Google Patents

Abstract

PURPOSE:To remove foreign matters and projects within a short time and obtain a desired withstand voltage by carrying out a prescribed withstand voltage treatment before or during application of pulsed high voltage. CONSTITUTION:Pulsed high voltage and d.c. voltage slightly higher than those applied prior are repeatedly applied by switching a high voltage power source 14 and a direct current power source 25 by a control apparatus. By this method, foreign matters which do not stand sufficiently by prior d.c. voltage application are brought to stand and eliminated or lessened by next pulsed high voltage, and projects which are lessened by prior pulsed high voltage are further lessened. As a result, a prescribed withstand voltage treatment is carried out at a relatively low high voltage and the treatment period is shortened.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a voltage resistance treatment method for cathode ray tubes.

(Prior art) For example, in a cathode ray tube such as a color picture tube, a high voltage is applied to some electrodes of an electron gun via an anode terminal in order to display a high-brightness, high-resolution image on a phosphor screen. , is formed in a structure that focuses and accelerates the electron beam emitted from the cathode.

In a cathode ray tube that focuses and accelerates the electron beam by applying a high voltage to the electrode of the electron gun, during operation, foreign matter such as dust that adheres to the high voltage application electrode or the electrode surface in the vicinity, or the electrode itself. Electric discharge occurs from protrusions such as bumps, which seriously impairs the quality of the screen. For this reason, in conventional cathode ray tubes, after evacuation, a pulsed high voltage with a peak voltage is applied to the high voltage application electrode from a high voltage source such as a Tesla coil or an Indakun Yong coil to remove the foreign objects and protrusions. A withstand voltage treatment is being performed to remove it.

In other words, when a pulse-like high voltage with a peak voltage is applied from a high voltage source, the protrusions protruding from the electrode surface gradually become smaller due to the energy of the discharge that repeatedly occurs between the electrodes, and the radiation emitted during the operation of the cathode ray tube. It is possible to prevent r-hi from occurring. On the other hand, regarding foreign matter adhering to the electrode surface, whether it is possible to remove it in the same way if it protrudes from the electrode surface by withstand voltage treatment, or if the length of the electrode is longer than the thickness, as shown in Figure 3, lying on the surface (1) and not protruding much from the surface;
There is a foreign substance (2) that hardly caused any problems with the withstand voltage, and after the withstand voltage treatment, due to vibrations applied to the cathode ray tube, these particles stand up as shown by the broken line and can deteriorate the withstand voltage during operation of the cathode ray tube. be.

In order to remove such foreign matter (2), it is necessary to increase the applied voltage so that a discharge occurs between the foreign matter (2) lying on the electrode surface (1), and to lengthen the treatment time. However, if the applied voltage is increased or the processing time is increased, there is a problem in that the glass neck of the electron gun will crack or peel due to the high discharge energy and heating caused by the discharge.

(Problems to be Solved by the Invention) As described above, the voltage resistance treatment method for cathode ray tubes is performed by applying a pulsed high voltage with a peak voltage to the required 7κ poles of an electron gun, and The projections, such as the bumps, can be gradually reduced in size by the energy of the discharge that repeatedly occurs between the electrodes, so that no discharge occurs during operation of the cathode ray tube. In addition, although dust adhering to the electrode surface can generally be removed in the same way, foreign matter that is long compared to its thickness and lies on the electrode surface during voltage withstanding treatment and hardly protrudes from the surface can be removed. There is a problem in that the particles are not removed and stand up due to vibrations applied after voltage resistance treatment, deteriorating the voltage resistance during operation of the cathode ray tube.

In order to remove such foreign substances, if the voltage applied during voltage withstanding treatment is increased and the treatment time is lengthened, the glass neck in which the electron gun is enclosed will be damaged due to the high discharge energy and heating caused by the discharge. Problems arise in that cracks and peeling occur.

This invention was made to solve the above-mentioned problems, and removes foreign objects and protrusions in a short time without increasing the applied voltage during withstand voltage treatment, thereby easily achieving the required withstand voltage characteristics. The purpose of the present invention is to obtain a voltage-resistant processing method that allows cathode ray tubes to be made with high voltage.

[Structure of the Invention] (Means for Solving the Problems) A withstand voltage treatment is performed by applying a pulsed high voltage having a peak voltage to an electron gun of a cathode ray tube consisting of a plurality of electrodes including a high voltage application electrode. In the withstand voltage treatment method for cathode ray tubes, - before or during the application of the pulsed high voltage,
A DC voltage lower than the second pulsed high voltage was applied continuously or intermittently, or an AC voltage was applied to carry out voltage resistance treatment to the extent that no discharge occurred between the two electrodes.

(Function) If a DC or AC voltage that is low enough not to generate a discharge between the electrodes is applied before or during the application of a pulsed high voltage with a peak voltage as described above, a voltage is formed between the applied electrodes. A direct current or alternating current electric field can erect foreign matter that cannot be erected with a pulsed high voltage, and then the pulsed high voltage applied can remove the erected foreign matter. By using it in combination with a pulsed high voltage, a cathode ray tube with good withstand voltage characteristics can be produced in a short time.

(Examples) Hereinafter, the present invention will be explained based on examples with reference to the drawings.

As shown in FIG. 1, the cone portion (1
A high-voltage power source (14) that generates a pulsed high voltage having a peak voltage is connected to the anode terminal (12) provided in 1) via a resistor (13). The high voltage application electrode (l7) of the electron gun (16) enclosed in the neck (15) is connected to this anode terminal (l2) by an internal conductive film (l8) and a bulb baser which is in pressure contact with this internal conductive film (l8). <19). On the other hand, the high voltage application electrode (17)
A plurality of grids (electrodes) (20) other than the above, a cathode (2l), and a heater (2
2) Connect the socket (23) to the base bin of several traps at the end of the neck (l5) to which it is connected. This socket 1
・(23) has a plurality of base pin holders into which the above-mentioned base pins are inserted, and each base pin holder has a resistance (
24). Furthermore, a DC power source (25) that generates a voltage lower than the high voltage power source (14) is connected to the anode terminal (12). These high voltage power supplies (
14) and the DC power source (25), the voltage value, and the application time are arbitrarily controlled by a control device (not shown).

For withstand voltage treatment, first connect the high voltage power supply (14) to the anode terminal (
12), a relatively low pulsed high voltage (27) having a peak voltage is applied as shown in FIG. By applying this pulsed high 7u pressure (27), the high voltage application electrode (17)
A discharge occurs between this electrode (l7) and the electrode adjacent to it. This discharge occurs on a relatively large protrusion (including foreign matter) on the surface of at least one of both electrodes, and the relatively large protrusion disappears or becomes smaller due to the energy of the discharge. Therefore, the above relatively low pulsed high voltage (
27), the number of discharges gradually decreases.

That is, if a relatively low high voltage (27) is continued to be applied for a certain period of time, the protrusion becomes smaller than a certain size and the number of discharges decreases.

At this stage, the high voltage (2
7) is stopped, and the DC voltage (28) lower than the high voltage (27) that had been applied from the DC power supply (25)
) is applied continuously or intermittently at a period of, for example, about 0.2 seconds for a certain period of time. By applying this DC voltage (26), the foreign object (2), which is longer than the thickness and lying on the electrode surface as shown in FIG. It stands up along the sides and becomes an apparently large protrusion (foreign object (2)).

Therefore, we stopped applying this DC lightning pressure (28) and
, -1i Switch to the ffE power supply (l4) and apply a pulsed high voltage (29) having a slightly higher peak voltage than the previous relatively low pulsed high voltage (27). Particularly, in this example, two levels of voltages with different high and low levels are applied as shown in (29a) and (29b) in the drawing. In this way, when applying a pulsed high voltage (29) with a higher peak voltage than the previous relatively low pulsed high voltage (27),
Foreign matter (2) that stood up due to the application of the above DC voltage (28)
At the same time, it is possible to further reduce the size of the protrusion that was reduced due to the previous relatively low pulsed high voltage (27).

Therefore, as shown in (27) to (33) in the drawing, the high voltage power supply (l4) and the DC power supply (25) are switched by the control device, and a pulse slightly higher than the previously applied pulsed high voltage or DC voltage is applied. When pulse-like high voltage and α-current voltage are repeatedly applied, foreign matter that was not sufficiently erected by the previous application of DC voltage is erected, and the next pulse-like high voltage further eliminates or reduces the size of the foreign matter. The protrusions that have become smaller due to the pulsed high voltage can be further reduced in size, and as a result, the required withstand voltage treatment can be performed at a relatively low high voltage, and the treatment time can be shortened.

In addition, in the above embodiment, a case was described in which a pulsed high voltage with a peak voltage and a DC voltage are repeatedly applied to a high voltage application electrode and an electrode adjacent to this high voltage application electrode, but in general, iJ YX pressure treatment When a pulsed high voltage is applied to a high voltage application electrode, high voltage is induced in other electrodes as well, and a discharge occurs between the adjacent electrodes. Although it is enough to just apply a DC voltage to the electrodes, a strong electric field is formed between adjacent electrodes and a weaker electric field between distant electrodes, so it is necessary to thoroughly remove foreign substances that adhere to each electrode. In order to stand up and remove, it is preferable to apply a DC voltage not only to the high voltage application electrode but also to an electrode located at a distance from the high voltage application electrode.

Furthermore, in the embodiment described in -L, a DC voltage was applied to make the foreign matter stand up, but even if an AC voltage such as a commercial sine wave AC voltage is applied instead of this DC voltage, the foreign matter will be made to stand up in the same way. be able to.

[Structure of the Invention] (Means for Solving the Problems) When performing voltage withstanding treatment by applying a pulsed high voltage having a peak voltage to an electron gun of a cathode ray tube consisting of a plurality of electrodes including a high voltage application electrode. , Before or during the application of the pulsed high voltage having the peak voltage, continuously or intermittently apply a DC voltage lower than the pulsed high voltage to the extent that no discharge occurs between the electrodes, or alternating current voltage. When voltage is applied, the DC or AC voltage causes foreign particles that were not removed by the pulsed high voltage to stand up, and the pulsed high voltage that is subsequently applied can remove the standing foreign particles. The withstand voltage characteristics of the cathode ray tube can be improved by applying voltage, and the withstand voltage can be treated in a short time.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a withstand voltage processing method which is an embodiment of the present invention, Fig. 2 is a diagram showing a method of applying pulsed high voltage and DC voltage, and Fig. 3 is a diagram showing a method of applying a high voltage in the form of a pulse and a DC voltage. FIG. 4 is an explanatory diagram of foreign matter lying on the electrode. 12... Anode terminal l6... Electron gun l7... High voltage application electrode 27... Pulse high voltage with peak voltage 28...
DC voltage 29... Pulse high voltage with peak voltage 30...
DC voltage 3l... Pulse high voltage 32 with peak voltage...
DC Voltage Chart Mark 110 Figure 2

Claims (1)

[Claims] When applying a pulsed high voltage with a peak voltage to the electron gun of a cathode ray tube consisting of multiple electrodes including a high voltage application electrode to perform withstand voltage processing, before or during the application of the pulsed high voltage, A method for treating a cathode ray tube with withstand voltage, characterized in that a DC voltage lower than the pulsed high voltage is applied continuously or intermittently, or an AC voltage is applied to an extent that no discharge occurs between the electrodes.