JPS63114022A - Spot knocking method for cathode-ray tube - Google Patents

Abstract

PURPOSE:To remove all portions acting as a field emission source when a cathode-ray tube is operated by repeating the active treatment and spot knocking of a Ba oxide layer stuck to the third grid. CONSTITUTION:First a cathode 15 is heated, a positive voltage is applied to the second grid 13 and the third grid 12 and 0V or negative voltage is applied to an anode 11 respectively, a voltage of 0V-negative several V is applied to the first grid 14, and an electron beam 26 hits the Ba oxide layer 24 on the grid 12 for active treatment. Thereby, the work function on the surface of the layer 24 is reduced, and field emission is mode easy to take place from a minor lug. Next, a high voltage is applied across the grid 12 and the anode 11 to perform spot knocking. Accordingly, discharge occurs between the lug 24 having the small work function and the anode 11, and the lug 24 disappears. By repeating the above process multiple times, all lugs 24 acting as field emission sources can be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a spot knocking method applied to improve the withstand voltage characteristics of a cathode ray tube.

[Prior Art] Generally, a color cathode ray tube has a glass bulb (4) consisting of a panel part (1), a funnel part (2) and a neck part (3), as shown in FIG. 4
) have an inner conductive film (5) and an outer conductive film (5) on the inner and outer surfaces of the
6) is provided. The internal conductive film (5) has a neck part (
3), and an electron gun assembly (9) is housed in the funnel part (2).
) has an anode (11) and a third grating (12) as shown in Figure 4.
), second grating (13), first grating (14), cathode (
15), a bead glass (1θ) for holding these electrodes together, a cup-shaped body (17), and a bulb spacer (18). A getter (19) is supported by a support rod (20) on the panel side of the cup-shaped body (17), and after the evacuation process of the cathode ray tube is completed, this getter (19) is heated from the outside by high-frequency induction heating. The barium particles (21) are scattered.

The degree of vacuum inside the tube during barium particle scattering is 10-3To
rr or more, a cloud of barium particles (22) is formed in front of the getter (18), and a part of the barium particles (21) reflected from this cloud reaches the anode (1) as shown in FIG.
The barium layer passes through the electron beam hole of 1) and is deposited on the circumferential surface of the electron beam passage hole on the anode (11) side of the third grating (12). Then, in the subsequent manufacturing process of the cathode ray tube, it is oxidized by oxygen gas and becomes a barium oxide layer (24).

This barium oxide layer (24) may become a source of field emissions during operation of the cathode ray tube. That is, during operation, the anode (11) has a voltage of 25 to 27 KV.
, the third grid (12) 4, Since a voltage of about 5 to 9 KV is applied, the third grid (12) and the anode (11)
A voltage of about 18 to 21 KV will be applied between the two. The third lattice (12) has minute protrusions (25).
It is unavoidable that there is a This causes unnecessary parts of the screen to emit light, reducing the quality of the image. The density of this field emission is generally calculated as Fowl er −N
It is shown by the ordheim relational expression.

Here, J is the field emission density, β is the electric field multiplication coefficient of the protrusion, and E is the third grating (12) and the anode (11).
electric field, φ is the work function of the third lattice plane.

From this equation, it can be seen that the field emission J becomes larger as β and E become larger, and as φ becomes smaller.

[Problems to be Solved by the Invention] FIG. 6 is an enlarged sectional view of the vicinity of the third lattice (12) and anode (11) in FIG.
5), on which is deposited a layer of notrium oxide (24) from the getter (18). In this situation, the third
When a high voltage of about 20 KV is applied between the grating (12) and the anode (11), the tip of the protrusion (25) has a large electric field multiplication factor β and a small work function φ, so the field changes as shown in the above equation. Emissions occur. In order to eliminate this, spot knocking is performed during the manufacturing process of cathode ray tubes, in which a high voltage approximately two to three times higher than that applied during operation is applied to force a discharge. Through this process, large protrusions (25) are successively removed, but small ones remain. When a cathode ray tube is operated in such a state, some of the scattered electron beams are absorbed into the barium oxide layer (24
) to activate barium oxide. The work function φ of the barium oxide layer (24) is approximately 1.7 eV, but when activated by electron beam impact, the work function φ increases.
Since this decreases to about 1.2 eV, new field emissions are emitted from areas where there was no field emission up to that point, causing a problem in that the quality of the image deteriorates.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a spot knocking method that does not generate new field emissions during operation of a cathode ray tube.

[Means for solving the problem] In the spot knocking method according to the present invention, first, Ov or a negative voltage is applied to the anode, and a voltage of 200 to 60 V is applied to the third grid.
An activation process is performed in which a voltage of 0V is applied to cause a third current to flow, activating the barium oxide layer attached to the third lattice, and electrons are applied to the third lattice and the anode side end of the third lattice. This is a spot-knocking method in which a spot-knocking treatment in which a high voltage is applied to an anode that activates the barium oxide surface is alternately performed multiple times.

[Function] The barium oxide layer adhering to the third lattice is activated by the activation treatment in the present invention, and the barium oxide layer is then applied.

Spot knocking removes the parts that generate field emissions, and by repeating this activation process and spot knocking, it is possible to remove all parts that become field emission sources when the cathode ray tube is operated. .

[Embodiments of the Invention] Examples of the invention will be described below with reference to FIGS. 1 and 2. Figure 1 is a longitudinal sectional view of the electron gun assembly (9), Figure 2
The figure is an enlarged sectional view of the third lattice and anode portion.

First, the cathode (15) is heated, and a voltage of 200 to 600V is applied to the second grid (13) and third grid (12).
A voltage of Ov or a negative voltage is applied to the anode (11), a voltage of OV to a negative number V is applied to the first grid (14), and electrons are passed through the third grid current to an extent that the third grid does not become red hot. An activation process is performed in which the beam f, (2B) collides with the barium oxide layer (24) of the third lattice (12). This reduces the work function φ of the surface of the barium oxide layer (24) to 1.
The voltage is lowered from about 7 eV to about 1.2 eV to create a state in which field emission is easily emitted from minute protrusions. Next, apply a high voltage of 60 to 70 KV to the third grid (12).
Spot knocking is applied between the anode (11) and the anode (11). Due to this.

The protrusion (24) with a small work function φ and the anode (
11), the protrusion (24) disappears, and a source of field emissions that may occur in the future during operation of the cathode ray tube can be removed.

However, during the spot knocking process, many discharges occur, which releases a large amount of gas such as oxygen, and the surface of the barium oxide layer (24), which had been activated by the previous activation process, is exposed to oxygen. Due to gas, etc., it will return to its original state and will no longer be able to be discharged. Therefore, by repeating the above-mentioned activation treatment and then spot knocking treatment 4 to 5 times, all the protrusions (24) that become field emission sources can be removed, resulting in a higher quality cathode m You can get the tube.

In the above embodiment, a cathode ray tube having a neck getter attached to the neck portion was explained as an example, but it goes without saying that the present invention can also be applied to a cathode ray tube having a funnel getter, and similar effects can be obtained.

[Effects of the Invention] As described above, the present invention includes an activation process in which a third lattice current is applied to activate the barium oxide layer attached to the third lattice, and after this activation process, the third lattice is Since the spot knocking method involves repeating the spot knocking process by applying a high voltage between the cathode and the anode, field emissions increase during the operation of the cathode ray tube and reduce the quality of the cathode ray tube. Therefore, it is possible to obtain a cathode ray tube with good withstand voltage characteristics.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of an electron gun for explaining one embodiment of the present invention, Fig. 2 is a partially enlarged view of the third grid and anode portion thereof, and Fig. 3 is a partially broken side view of the cathode ray tube. Figure 4 is an enlarged view of the electron gun part, Figure 5 is a vertical cross-sectional view of the electron gun to explain the conventional spot knocking method, and Figure 6 is a partially enlarged view of the third grid and anode part. It is. (8)...electron gun, (11)...anode, (12)...
...Third lattice, (15)...Cand, (19)...
・Getter, (24)...butyrication/helium layer, (25)
···protrusion. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) An activation process in which a voltage is applied between the third grid and the cathode of the cathode ray tube to flow a third grid current; and after this activation process, a high voltage is applied between the third grid and the anode. A spot knocking method for a cathode ray tube in which a spot knocking step of applying an electric current is repeated multiple times.