JPS58499B2 - Sankabutsuinkiyokukitaiyougokin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an alloy for an oxide cathode substrate that is particularly suitable for application to cathode ray tubes such as color television picture tubes.

Conventional alloys of this type include Ni-Mg, Ni-8LNi-
Materials made of Al, Ni-W-Mg, etc. are used.

A base metal made of this alloy is fixed to the cathode sleeve, and an alkaline earth metal carbonate, for example BaCO3, is deposited on the base metal.

Then, heat it at a predetermined temperature to thermally decompose BaCO3,
As a result, an oxide consisting of BaO is generated on the base metal.

This oxide is reduced by the above-mentioned Mg, Si, Al, W, etc. that diffuse into the base metal Ni, and electron emission (
Ba, which has a small work function and causes emissions), is generated.

Therefore, the emission characteristics are determined by the reducing metal in the base metal, but since the above-mentioned reduction reaction must be performed, the initial characteristics are particularly poor.

In addition, since the rate of diffusion of reducing metals in the base metal is high, BaO is quickly consumed, which reduces the lifespan of the cathode.
The disadvantage is that the lifetime) is very short.

FIG. 1 shows the temporal change in electron emissivity when a base metal made of Ni--Mg is used.

This figure shows the conditions when the proportion of Mg in the base metal is changed in three ways, but the initial characteristics are extremely unstable and high emissivity cannot be maintained over time. That is clear.

Further, the time required to reach the end of life is short, and as a result, the lifetime is shortened, and the image on the television picture tube tends to become dark.

The present invention was invented to correct the above-mentioned defects, and includes 0.033 to 0.23% by weight of Ba and 0.0% by weight of Ba.
The present invention relates to an alloy for an oxide cathode substrate composed of 3 to 0.1% by weight of Mg, 0.025 to 0.20% by weight of BaO, and the balance mainly consisting of Ni.

By configuring in this way, it is possible to facilitate the emission, particularly to make the initial characteristics stable and good, and to extend the lifetime of the emission.

Next, an embodiment in which the present invention is applied to an oxide cathode substrate alloy used in a color television picture tube will be described with reference to FIGS. 2 and 3.

First, the structure of the oxide cathode 1 will be explained with reference to FIG.

In this cathode, a circular cap 3 is fitted and fixed on the face plate side of a cylindrical sleeve 2, and a Ba0 layer 4 is formed on the surface of the cap 3 by spraying or the like.

Further, a heater 5 is disposed in the inner space of the sleeve 2 to heat the cathode 1 to a predetermined temperature.

The cap 3 is used as a cathode base metal, and contains 0.033 to 0.23% by weight (for example, 0.09% by weight) of Ba and 0.03 to 0.1% by weight (for example, 0.0% by weight).
8% by weight) of Mg, and the balance consisting of 0.025 to 0.20% by weight (for example, 0.06% by weight) of Ba05Ni.

In addition, Ba is 0.09 to 0.12% by weight, and Mg is 0.0% by weight.
5 to 0.09% by weight, BaO is preferably 0.06 to 0.08% by weight, and Ba/(Ba+Ba0
)=0.4 to 0.7, preferably 0.6.

In this case, the total amount of BaO and BaO is 0.083
~0.33% by weight, Ba/(Ba+Ba0)=0
．． 6, Ba may be 0.05 to 0.2% by weight.

Next, the emission characteristics of the cathode 1 will be explained.

First, during operation of this cathode, Mg in the cap 3 diffuses to the surface and reaches the Ba0 layer 4, thereby causing the next reduction reaction, as in the conventional case.

BaO+Mg-+Ba+MgO Since Ba generated as a result has a small work function, it causes emission in the Ba0 layer 4.

The Naori aO layer 4 is a BaC03 layer deposited in advance by a heater 5.
It may be thermally decomposed by

However, since Ba is mixed in the cap 3, this Ba diffuses and is adsorbed into the Ba0 layer 4 regardless of the above-mentioned reduction reaction, thereby directly supplying Ba and contributing to emissions.

In this case, Ba and Mg in the cap 3 interact with each other on their respective diffusions.

That is, the diffusion of Ba is suppressed by Mg, and the diffusion of Mg is promoted by Ba.

Since Ba and Mg are mixed in the above ratio, Ba
The overall contribution of Mg and Mg to the emission characteristics is extremely good, and especially the initial characteristics are stable.

Further, a predetermined amount of BaO is mixed into the cap 3, and this BaO reduces the diffusion rate of Mg and Ba.

As a result, the amount of Mg reaching the BaoBao layer 4 is suppressed, and the emission lifetime is also greatly improved.

Improvements in these characteristics were revealed through emission measurements, diffusion, life tests, etc.

Note that if Ba is less than 0.033% by weight, it is difficult to obtain a high electron emissivity, and if Mg is more than 0.03% by weight, the initial characteristics of emission are unstable and it is difficult to maintain high electron emissivity. However, if BaO is less than 0.025% by weight, the effect of increasing the lifetime of the cathode is small.

On the other hand, Ba, Mg and BaO are each 0.23% by weight.
, 0.1% by weight and 0.20% by weight or more, no improvement in properties is observed, and on the contrary, the workability of the alloy deteriorates.

FIG. 3 shows the temporal change in electron emissivity when using the cathode substrate alloy in this example on the same scale as in FIG. The results are shown when the value is changed to .

As is clear from FIG. 3, the electron emissivity, especially the initial characteristics, is extremely stable compared to the conventional one shown in FIG.

For example, if the Mg content is 0.09% by weight, the Mg content is equal to 0.0897897% by weight in Figure 1.
It can be seen that the electron emissivity is maintained higher than that of the previous one, and the time taken to reach the end of life is greatly increased.

In the case shown in Figure 1, the electron emissivity does not increase even if the Mg content is increased, but in this example, even if the Mg content is not changed much, the addition of Ba significantly improves the electron emissivity. Get results.

For reference, we have shown a case where the Mg content is very low at 0.006% by weight, but it is clear that in this case, the electron emission characteristics will be somewhat worse, but the lifetime will still be long enough. Ru.

As mentioned above, in the present invention, a predetermined amount of Ba is mixed in addition to a predetermined amount of Mg in the cathode substrate, so that Ba, which causes emissions, is directly removed without relying on the reduction reaction between BaO and Mg. This makes it possible to easily emit electrons and, in particular, to make the initial characteristics extremely stable and good.

Furthermore, since it contains BaO to suppress the diffusion of Mg and Ba, Ba, which is a source of the above-mentioned reduction reaction and a cause of emissions, can be retained for a long time, thereby significantly increasing the lifetime of the cathode. It becomes possible to do so.

[Brief explanation of the drawing]

FIG. 1 is an electron emission characteristic diagram of a conventional cathode. 2 and 3 show an embodiment in which the present invention is applied to a cathode for a color television. FIG. 2 is a schematic cross-sectional view of the cathode, and FIG. 3 is a diagram of electron emission characteristics of the cathode. It is. In addition, in the symbols used in the drawings, 2 is a sleeve, 3 is a cap, and 4 is a BaO layer.

Claims (1)

[Claims] 10.033-0.23% by weight of Ba and 0.03-0.
．． 1 weight percent Mg and 0.025 to 0.20 weight percent B
An alloy for an oxide cathode substrate composed of aO and the remainder mainly consisting of Ni.