JPH0447637A - Manufacture of color cathode-ray tube - Google Patents

Abstract

PURPOSE:To remove A stray by either a G2 electrode lower plane or its lower electrode, especially a G1 electrode system, to improve withstand voltage of the G1 electrode system by carrying G2 electrode indirect knocking in the knocking process. CONSTITUTION:After sealing, evacuation, and gettering are carried out, front knocking and load-aging are carried out. During the load-aging, a Ba oxide is vaporized from a cathode 7 and adheres to the surface of a G1 electrode 1. Owing to this, A stray of the G1 system is generated and it causes the decreasing of withstand voltage. As measures against it, G2 indirect knocking is carried out during the knocking process carried out after that, so that spark is generated between a G2 electrode and a G1 electrode and the Ba oxide adhering to the surface and the periphery of a hole of the G1 electrode is thus removed and cleaning is carried out to improve withstand voltage.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for manufacturing cathode ray tubes such as color picture tubes and color display tubes, and in particular to a knocking treatment suitable for high-definition, high-speed color cathode ray tubes. The present invention relates to a method for manufacturing a cathode ray tube.

[Prior Art] In general, in the manufacturing method of color cathode ray tubes, fine protrusions on the surface of each electrode constituting the electron gun or press molding are performed as a post-process of the manufacturing assembly process or as a regeneration process of bulbs with poor withstand voltage. Knocking treatment is applied to remove the burrs caused by this process, as well as foreign matter such as dust attached to the surface, to reduce leakage current, and to obtain stable characteristics over a long period of time that are resistant to external heat and vibration. It is carried out.

Conventionally, as this type of knocking treatment process, a float knocking method (see, for example, Japanese Unexamined Patent Publication No. 55-154034), an indirect knocking method, etc. are known.

Figure 3(a) shows the conventional float knocking method.
The connection configuration of an example of a type (pi-potential/uni-potential type) electron gun applied to a color cathode ray tube is shown, and Fig. 3(c) shows the actual structure of this B-U type color cathode ray tube electron gun for reference. . In FIGS. 3(a) and (C), 1 is the Gl (first grid) electrode, 2 is the G2 (second grid) electrode, 3 is the G3 (third grid) electrode, and 4 is the G2 (second grid) electrode.
is the 04 (fourth grid) electrode, 5 is the G5 (fifth grid) electrode, 6 is the G6 (sixth grid) electrode, 6a is the shield cup integrally coupled to the G6 electrode, 7 is the cathode,
8 is a heater, and 9 is a stem.

The normal operating voltage is - for example, the heater 8 is 6.3v
, cathode 7 is +250-OV, G] electrode 1 is OV,
G2 electrode 2 is 0.5KV-0.7KV, G3 and G5
Electrodes 3 and 5 are at 7KV, and G4 and G6 electrodes 4 and 6 are at about 25KV. During the knocking process, a positive voltage of 65 KV, for example 65 KV, is applied in pulses from the power supply 10 to a voltage that is twice or more than three times the operating voltage. Applied to the G4 electrode. The pulse repetition frequency is 50 I (z), and the pulse width is approximately 0.05 m5ec.The characteristics of this float knocking method are that the G3 electrode and the G5 electrode are not connected to any outside (floating state), and the G1 electrode 1 −
and G2 electrode 2 is grounded (connected to Ov).

As a result, arc discharge occurs between the upper surfaces of the G6 electrode and the G2 electrode, and between the upper surfaces of the G3 and G2 electrodes. This is done by passing through the G5 electrode, and removing protrusions and foreign objects on the electrode between these electrodes.

In addition, Fig. 3(b) shows that the conventional indirect knocking method is
An example of a connection configuration applied to a color cathode ray tube of a U-type electron gun is shown. In FIG. 3(b), the point in which the G3 and G5 electrodes 3 and 5 are grounded via the resistor Ra is the same as in FIG. 3(a).
Unlike the floating method, other connection configurations are
This is the same as in Figure (a).

In this indirect knocking method, when a positive pulse of, for example, 65 KV is similarly applied from the power supply 10 to the G6 electrode, the discharge current flows through the resistor Ra due to the discharge between the G6 and G5 electrodes 6 and 5, and a high voltage is applied to the 65 electrode. This high voltage causes a secondary discharge to occur between the G5°G3 electrode and the G2 electrode. As a result, a knocking effect is produced between the upper surfaces of the G6 electrode and the G2 electrode.

[Problems to be Solved by the Invention] Recently, color cathode ray tubes (CDTs) used for color displays and the like are becoming increasingly high-definition and high-speed (high-frequency characteristics are improved by high-speed scanning). In order to achieve higher definition, it is necessary to narrow the distance between the cathode and the G1 electrode in order to improve focus characteristics. Furthermore, the interval between the G1 electrode and the 02 electrode becomes narrower.

When the distance between the cathode and the 61 electrode becomes narrower, aging treatment and ITC (Tintegrated Tube Co., Ltd.)
During the preheating of the cathode ray tube with complete deflection yoke adjustment, Ba oxide (barium chloride) evaporates from the cathode on the G1 electrode surface (around the hole of the Gl electrode, etc.) and the G2
It tends to adhere to the lower surface of the electrode (cathode side surface).

As a result, G1-based A stray (cold emission from the Gl electrode reaches the phosphor screen and makes it glow) and spot residual defects (light spots remain on the phosphor screen even after the power is turned off) A problem arose in that

Furthermore, in order to increase the speed, the voltage applied to each electrode becomes higher and higher. Therefore, the potential gradient between the electrodes has become extremely high. For example, in recent color cathode ray tube electron guns, the cathode and
Approximately 115 to 140 ILm between 1 electrode, G1 and G
The distance between the two electrodes has become narrower, to about 250 μm, and this trend continues, and the distance between the Gl and G2 electrodes has begun to reach 80 μm. For this reason, the potential gradient, which was conventionally about 1700 V/B at most between the Gl and G2 electrodes, has recently become as high as 3000 V/nun. The same can be said about the gap between the cathode and the G1 electrode. This makes leakage electrodes more likely to occur.

However, both the float knocking method and the indirect knocking method according to the conventional techniques mentioned above are intended to have a knocking effect on the upper surface of the G2 electrode or the electrode above it (improvement of withstand voltage by removing protrusions and foreign matter on the electrode surface, etc.). G that is newly generated in high-definition tubes, etc.
No consideration has been given to the problems of A-stray and reduction in withstand voltage caused by the lower surface of the two electrodes or lower electrodes, especially the problems of A-stray and reduction in withstand voltage of the G1 series.
For this reason, there was a problem that yield and work efficiency were reduced.

Therefore, an object of the present invention is to solve the problems of the prior art described in 1.
An object of the present invention is to provide a method for manufacturing a color cathode ray tube, which is equipped with a knocking process that can eliminate A stray caused by a one-electrode system and improve the withstand voltage of the electrode system.

[Means for Solving the Problems] In order to achieve the above object, the present invention is characterized in that, as its basic concept, 02-electrode indirect knocking is performed in the knocking process.

That is, as a connection configuration for knocking, the G2 electrode is grounded via a resistor, the G1 electrode is grounded, and the upper electrode (G6 electrode in the case of a BU type electron gun) is connected to a high voltage for knocking (e.g. The configuration is such that it is connected to apply an inductive high-voltage pulse power source.

The non-king treatment according to the present invention is effective for knocking treatment both before and after road aging, but post-knocking performed after road aging is particularly effective as a measure for removing Ba oxides.

Further, this knocking treatment can also be used as a means for regenerating a tube with a voltage failure after preheating in the ITC process.

[Effect] The effect based on the above configuration will be explained.

According to the present invention, by applying a high voltage to the upper (G6) electrode, an arc discharge is generated from the upper (G6) electrode to the 02 electrode, and a spark current due to this discharge flows into the resistor connected to the G2 electrode. This current generates a voltage at the G2 electrode, which again induces a secondary discharge (spark) between the 02 and 01 electrodes (so-called indirect knocking effect). This secondary spark causes G2
Foreign matter such as dust adhering to the lower surface of the electrode or the G1 electrode is scattered and removed. In particular, in the post-knocking process, B deposited from the cathode to the G1 electrode during the road knee zinc
a oxide can be effectively removed. In this way, G1 system A stray defects can be eliminated and the withstand voltage can be improved.

[Example] An example of the present invention will be described below with reference to FIGS. 1 and 2.

Figure 1 shows the configuration of the electron gun contact during knocking when the present invention is applied to a color cathode ray tube of a B-U type electron gun, and parts with the same names as in Figures 3 (a) to (C) are given the same reference numerals. The explanation will be omitted. It is also assumed that the operating voltage of each electrode is the same as in the case of FIG.

In FIG. 1, a feature of this embodiment is that the G2 electrode 2 is grounded via a resistor Rb. The G1 electrode and the cathode electrode are grounded as they are. An induction high voltage power supply ]O is connected to the G6 electrode 6 (internally connected to the G4 electrode 4), and a pulse voltage (positive 6
5KV, 50Hz, pulse @0.05m sec
). The other electrodes (G3 electrode 3 and G5 electrode 5) are left open.

When the power supply 10 is operated in this state, a spark is generated from the G6 electrode to the electrode 2 through the electrodes 5 to 3. As this spark current flows through the resistor Rb, a voltage is induced in the G2 electrode, thereby again generating a secondary spark between the G2 electrode and the 01 electrode. As a result, G
Cleaning is performed by removing dust, Ba, etc. that have adhered to one electrode. The resistance value of the resistor Rb may be adjusted according to the applied voltage of the power supply 10, the distance between the G2 and 01 electrodes, or the distance between the G1 electrode 1 and the cathode 7, thereby increasing the frequency of spark induction from the G2 electrode to the G1 electrode. (The number of pulses at which a spark is generated) can be restricted. According to experiments, in the case of this example, the resistor Rb
When the resistance value was set to 10Ω, a good knocking effect was obtained. Its resistance value ranges from several ohms to several hundred ohms
It can be adjusted within the range of.

In the above embodiment, the G3 electrode 3 and the G5 electrode 5 are in an open state, but they may be grounded via a resistor in the same way as the G2 electrode, and depending on this state, the G6 electrode 6 is connected to the G2 electrode 2. It is possible to limit the frequency of spark jumps.

However, according to experiments, G3. Compared to the case where the G5 electrode is open, when the G3°G5 electrode is grounded through a resistor, sparks jump into the cathode 7 more frequently, and when this spark jump occurs, it damages the cathode 7 and the cathode G3.7 may deteriorate the emission performance of G3. It is better to perform the knocking treatment with the G5 electrode open.

Next, an outline of the manufacturing process of a color cathode ray tube to which the present invention is applied will be explained with reference to the flowchart shown in FIG.

Seal in step 21, exhaust in step 22, step 2
After gettering is performed in step 3, pre-knocking is performed in step 24, and road aging is performed in step 25. During load aging, Ba oxide evaporates from the cathode 7 and adheres to the surface of the G1 electrode 1, as described above. This generates Gl-based A stray, which causes a decrease in withstand voltage performance.

As a countermeasure against this, by adopting the 62-direction knocking of the present invention in the post-knocking step 26 to be performed afterwards,
A spark is generated from the G2 electrode to the G1 electrode, thereby removing Ba oxide adhering to the surface and around the holes of the 01 electrode, cleaning it, and improving the withstand voltage performance. In addition, in order to regenerate GI-type withstand voltage defective tubes detected in subsequent inspections such as the primary inspection 27 and the secondary inspection 29 after reinforcement 28, or in the ITC process 31 after preheating 30, offline By providing the G2 indirect knocking device shown in FIG. 1, it is possible to regenerate a defective pipe.

According to this embodiment, the frequency of spark generation (
Since the number of seconds it takes to generate a spark after applying voltage can be controlled from 1 to 1, it improves withstand voltage performance without reducing emission emission performance due to sparks jumping into the cathode 7. Defective tubes can be regenerated.

Further, according to the manufacturing system shown in FIG. 2, the knocking treatment according to the present invention can be applied to all the color cathode ray tubes to be produced, so that the withstand voltage performance of all the color cathode ray tubes can be improved.

In addition, since it is now possible to regenerate tubes that have been detected to have voltage resistance defects, the recyclability rate (number of tubes that can be regenerated), which was previously close to 0, has increased to almost 100% (over 98%).
It can be increased up to.

In the above embodiment, a case where the application is applied to a BU type electron gun is shown, but other types of electron guns, such as the EA-UB type (
Elliptical aperture unipotential pi potential type), Hi-Fo type (high focusing voltage BPF type), BPF type (pi potential focus type), Hi-UPF type (high focusing voltage unipotential focus type) ), etc., the non-king method according to the present invention can also be applied. In this case, if the G6 electrode is far from the other electrodes, such as the EA-UB type or the EA-D Shiba 5 F type (Ellilapse Aperture Dynamic Focus type), use the high voltage instead of 66. It is also possible to apply to 65 electrodes.

"Effects of the Invention" As explained in detail above, according to the method for manufacturing a cathode ray tube of the present invention, in the knocking step, the G2 of the electron gun is
By inserting a resistor into the electrode and grounding it, grounding the G1 electrode, and applying a high voltage from the upper electrode, for example, G6,
Since a secondary spark is generated between the G2 electrode and the G1 electrode, Ba oxides, etc. on the underside of the G2 electrode and around the G1 electrode are cleaned, significantly improving the withstand voltage performance of the G1 electrode system. It has the effect of being able to

[Brief explanation of drawings]

Fig. 1 is a connection configuration diagram for knocking an electron gun according to an embodiment of the present invention, Fig. 2 is a flowchart of the manufacturing process of a color cathode ray tube, and Figs. 3 (a) and (b) are a diagram of a conventional color cathode ray tube. FIG. 3(c) is a diagram showing the connection configuration when performing knocking of the electron gun. FIG. 3(c) is a diagram showing the configuration of an electron gun for a general color cathode ray tube. ]...First grid (G1) electrode, 2...
...Second grid (G2) electrode, 3...Third grid (G3) electrode, 4...Fourth grid (G
4) Electrode, 5...Fifth grid (G5) electrode,
6...Sixth grid (G6) electrode,...Cathode electrode, 8...Heater electrode, 9...Stem. ]-〇・・・Induction high voltage power supply, b ・Resistor.

Claims (1)

[Claims] 1. In the knocking process of an electron gun for a color cathode ray tube, the second grid electrode is grounded via a resistor, the first grid electrode is grounded, and a high voltage is applied to the upper electrode, so that the upper electrode is connected to the second grid electrode. A spark is generated in a grid to cause a spark current to flow through the resistor, the spark current induces a voltage in the second grid, and the induced voltage induces a secondary spark from the second grid to the first grid. A method for manufacturing a color cathode ray tube, characterized in that a knocking treatment is performed using a method.