JPS60138822A - Impregnated cathode - Google Patents

Abstract

PURPOSE:To achieve an increased performance and an improved life of an impregnated cathode by coating it with a single-phase film or an alloy film composed of one or some elements selected from among Os, Ir and Ru so as to enhance the characteristic of the cathode during the initial stage of its life and by selecting the component elements of the porous base body so as to maintain the characteristic of the cathode during the last stage of its life. CONSTITUTION:After a binary or multi-element porous base body composed of a heat-resisting metal and one or some elements chosen from among Os, Ir and Ru is impregnated with an electron-discharging substance of a barium-aluminate-system oxide to make an impregnated cathode, the thus made cathode is coated with either a single phase film composed of one element selected from among Os, Ir and Ru or an alloy film composed of an arbitrary combination of the above elements. For instance, after a porous base body composed of a heat-resisting metal (ex., W particles 1) and Os particles 3 is impregnated with an electron-discharging substance 2, the thus obtained body is coated with a single- phase film 4 of Os.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an impregnated cathode used as a cathode at the end of a cathode ray tube or an image pickup tube.

[Background of the invention]

Conventionally, the cathode commonly used in cathode ray tubes, image pickup tubes, etc. consists of a porous ηW substrate 1 completely impregnated with an electron-emitting substance 2, barium alumina-1-based oxide, as shown in Figure 1(a). With a wet impregnated cathode, the saturation current density of the impregnated cathode is 6-6 A/cm2 when the cathode humidity is 1000 °C. On the other hand, if the surface of the impregnated cathode is coated with an O3 film or an Ir film, the cathode temperature is 1000.
A high saturation current density of about 10 A, 7 cm2 is obtained at °C (P, Zalm and A, J, Av
An Stratum: Ph1lips Tech,
Imoev, 27 (1966), Special Publication 1977-21
346). However, when an impregnated cathode coated with the above-mentioned Os film or ``film'' is used under a high emission current load, the coating layer may be damaged due to bombardment or arc discharge due to positive ion gas generated in the vacuum chamber. This often causes breakage accidents and deterioration of emissions.Recently, as shown in Figure 1 (1)), Wresor 1 is applied to a porous substrate. A trinox-type cathode that does not require a coating layer 4 using an alloy of 05 grains 5 or Ir grains has been proposed (M, C, Green, cl
aloAppl, 5urf, Sci, 8(19
81) 13, JP-A-53-13348). This cathode is expected to be used as a high current density cathode because it essentially does not undergo emitter/ion deterioration even when subjected to ion bombardment or arc discharge. However, in order to reach a high electron emission state, this Yin Jii14 fi1oo.

The disadvantage of this invention is that it is difficult to use in general consumer equipment because it requires aging for close to 00 hours at ℃. The objective is to obtain an impregnated electrode with high performance and long life.

[Summary of the invention]

In order to achieve the above object, the impregnated electrode according to the present invention has barium alumina・In an impregnated electrode impregnated with a charge-emitting substance of an oxide, O5 is added to the surface -1-5 of the cathode.
, ], r, 1 is also coated with a 111-phase j imitation made of any one of 11 or an alloy phase film made of any combination of the above elements, so that the initial 1, v properties of SJ are reduced to the above coating layer. The characteristics in the later stages of life are maintained using the constituent elements of the porous substrate.

[Embodiments of the invention]

Next, an embodiment of the present invention will be explained along with the same song.

FIG. 2 is a 161-plane view of one embodiment of the impregnated electrode according to the present invention, and FIG. 5 is a diagram showing the change over time in the saturation current density when the impregnated electrode of the gods is mounted on a color cathode ray tube. In the embodiment shown in FIG. 2, a porous substrate made of a heat-resistant metal, for example, W grains 1 and 05 grains 6, is impregnated with an electron-emitting substance 2, and the surface thereof is completely coated with a single film of O5. This is what I did. Figure 1(a) shows a conventional impregnated electrode with a diameter of 5 to 10 μm.
In a porous substrate with a porosity of 20% formed of W grains 1 of
4 BaO+AA20. It was produced by impregnating a barium aluminate-based oxide of +CaO mixture as the electron-emitting material 2. The impregnation conditions are 1700° C. for 6 minutes in a gas atmosphere. Next, a matrix type cathode (not shown in FIG. 1 (1)) is made of a porous substrate made of a mixture of W grains 1 and U grains 3 with a ratio of 20 atomic %, and the same as above. It was prepared by impregnating the electron emitting material 2. W grain 1
and Us J', :13 particle size is 5-10μ, respectively.
It is m.

Furthermore, an Os film is applied to the normal A hairstyle cathode at 5000 A.
A corrugated coated impregnated shade was fabricated using the AR beam evaporation method to a thickness of . - The reporter-impregnated cathode was mounted on each color cathode ray tube and knee-jerked at 1100℃ for 1 hour, and then the heating temperature of the cathode was increased to 1000℃.
The curves shown in FIG. 6 are the results of measuring changes over time in the saturation current density at .degree. Normal @l),
The shaped electrode has a saturation current density of 3-4 A/cm' in a circular shape with a curve M5, and almost no deterioration of the emission is observed.

As shown in curve 6, the saturation current density of the W-Os matrix electrode with a substrate made of a mixture of W grains and 05 grains is inferior to that of a normal impregnated electrode at the initial stage of heating, but as heating continues, the saturation current density increases to 1000 After the time has elapsed, write the Os
The saturation current density is even higher than that of the immersion type cathode, which has a undulating membrane. The cause of this phenomenon is not well understood, but it is thought to be related to the special state of the W-Os porous substrate. In addition, as shown in curve 7 in the same figure, the coated impregnated cathode, in which the surface of the conventional impregnated electrode is covered with an O5 film, has a high saturation current density of IOA/cm2 of less than 7 J, but during continued heating. I sometimes feel like emino/yo/deterioration. This phenomenon occurs when the above measurement is performed at a high current +l.
li,: heating life test at below degrees /ζ, +
This is because the O3 film is damaged by bombardment by E gas ions and arc radiation. As shown in the above, the coated impregnated cathode exhibits superior characteristics at the early stage of its life, while the matrix electrode exhibits superior characteristics after more than 1000 hours have elapsed. The impregnated electrode according to the present invention is formed by combining a 11-7 trinodic cathode and a covered impregnated cathode.

Example 1 Using W grains with a grain size of 5 to 10 μm as the heat-resistant metal,
4BaO + At20. The surface -I- of a matrix cathode formed by impregnating a CaO mixture as an electron-emitting substance in a H2 gas atmosphere at 1700°C during a filtration period was coated with an O5 film to a thickness of 5000 A by electron beam evaporation. A shaped cathode was fabricated.

The above cathode was mounted on a color brown plate, and the temperature was 110 mm under vacuum.
Curve 8 of the first curve shows the results of measuring the change in saturation current density over time when the heating temperature of the cathode was set to 1000° C. after performing knee-jinking at 0° C. for 1 hour. Is the O5 film coated 11W-Os matrix type cathode of this example highly saturated from the start of the above measurement? If the lLl dense flow is applied, there is almost no deterioration of the Emison Yono over time. It seems that the high saturation current density at the beginning of the life depends on the properties of the 1l-1iO5 film, and the properties after long-term heating depend on the properties of the W-Osmal-IJ Nox cathode. Therefore, the reason why there is no significant ion bombardment emission deterioration during the heating stress test described in ``-'' is because a 1.1 SOx type cathode is used in the W-S. 1
From the above results, W-OS maI/linox type cathode 1 and OS1
This Example C, which was subjected to a pattern coating treatment, has excellent initial characteristics of Emino/Yon and has excellent characteristics of long life.

Note that the ratio of Os powder mixed in the W grains was varied in region 1 from 1 original f% to 50 at%, and after firing the N-Us porous substrate and impregnating it with the electron emitting substance, the Os powder was mixed into the W grains. 0 membrane
．． An impregnated cathode was prepared by coating 57 m of film.

” By mounting the second cathode on a color cathode ray tube, vacuum de-11
After performing knee zinc at 00℃ for 1 hour, the cathode temperature was increased to 10℃.
The change in saturation current density over time at 00°C was measured. As a result, the characteristics of Example 1 shown in curve 8 in FIG. 6 could not be obtained outside the composition range of 5 at.% to 30 at.% when Os grains were mixed with W grains. When the above ratio was less than 5 at %, the effect of the Hw-Os7 trinox cathode was not observed, and a phenomenon similar to that of song NM7 in Figure 1 occurred. ”-The proportion is 3
When it exceeds 0 atomic %, it is considered that the W component that reduces the barium aluminum -1-based oxide is small, and the generation of free Ba that becomes emino/yon center is insufficient.

Therefore, it is preferable that the ratio of the 05 grains mixed into the W grains is within the range of 5 to 601%.

Furthermore, an impregnated cathode made of a porous substrate containing 20 atomic percent of 05 grains mixed with W grains, and an OS coating layer of 001 μ
An impregnated cathode was fabricated by coating by varying the thickness from η to 5 μm. ” - The cathode was mounted on a color cathode ray tube and exposed under vacuum for 110 minutes.
After performing knee zinc at 0℃ for 1 hour, the cathode temperature i
Changes in saturation current density over time at ooo°C were measured.

As a result, when the coating thickness was outside the range of 01 to 2 .mu.IT, the characteristics shown in curve 8 in FIG. 6 above could not be obtained.

If the thickness of the coating is less than 0.1 μm, the characteristics will deteriorate due to insufficient coverage of human blood on the cathode, and if the thickness of the coating exceeds 2 μITI, the particle diameter interval, which is a path for surface diffusion of the emitter phase, will be blocked. It is thought that this is to put it away. Therefore, the coating of the cathode surface j! Day: J-0. The W-Os porous substrate described in Example 1 of ``Working Example 2'', which is preferably within the range of 1 to 2 μITI, and 05
11゛ was used instead of Os0 in the film. Particle size 5-10
1.5 μm W grain with particle size 5-10 μIn. 4 B ao +
It was impregnated with an electron-emitting material of A-/,03+CaO mixture under the same conditions as in Example 1 above, and its surface was coated with a 1R film to a thickness of 5000 A by electron beam evaporation.
An Ir coated W-1r matrix cathode was prepared.

This cathode was mounted on a color cathode ray tube and
After knee-jinking at ℃ for 1 hour, it was heated to 1000℃ and the change in saturation current density over time was measured.The results showed the same characteristics as curve 8 in Fig. 3: f: No, good initial characteristics of emission, Even after being heated for a long time under a high current load, there was no deterioration over the lifespan.

Example 6 A blue immersion cathode was produced in the same manner as in Example 1 using 1tu instead of Os in the W-Os porous substrate and Os film described in Example 1. dl) [defined.

4B on a porous substrate consisting of a mixture of W grains and I (U grains)
An impregnated electrode was formed by coating the aO+At203-1-CaQ mixture with the electron emission material e[fjl, and then the I(u film. The thickness is the same as in Example 1. This impregnated electrode was mounted on a color cathode ray tube and heated at 1100°C.
After time aging, we measured the change in saturation current density over time at a cathode temperature of 1000°C. As a result, Emino/Yon's initial i9+ characteristics were good, and the high current negative i1! Even when heated in the f state for a long time, there was no deterioration due to the lifetime, and the No.

Example 4 - The W-Os porous substrate described in Example 1 and the O
In place of Qs in the 8 film, an impregnated electrode was prepared in the same manner as in Example 1 of the manual, using any two-element or multi-element alloy of 05, jr, I(, u). The effects were exactly the same as in each of the above examples.

In each of the above embodiments, examples were described in which W was used as the heat-resistant metal material constituting the porous substrate.
The effects of the present invention can also be obtained using the -Mo alloy. However, among these heat-resistant metals, tungsten has the highest melting point, and a porous substrate using tungsten is the most stable both thermally and mechanically, and can moderately reduce alumina-1 oxide. Among the heat-resistant metals, W is the best because free Ba'f, which becomes the emino/yo/center of electron emission, can be generated over a long period of time.

〔Effect of the invention〕

As described above, the impregnated electrode according to the present invention has electrons of barium aluminate-based oxide in a bi- or multi-element porous substrate consisting of a heat-resistant metal and any one of O5, Ir, and Ru. In an impregnated electrode impregnated with a releasing substance, the surface of the cathode consists of a single phase consisting of either 05, Ir, or 7U, or any combination of elements. By covering one layer of the alloy phase, the coating film improves the initial properties and prevents the constituent elements of the porous substrate from causing deterioration due to the emisions/yons even during long-term heating under high current loads. /ζ, it is possible to obtain a high-performance and long-life impregnated electrode. Therefore, the present invention not only contributes to improving the performance and reproducibility of impregnated electrodes, but also
Its industrial value is extremely high, as it contributes to higher brightness in cathode ray tubes and image pickup tubes, as well as to finer definition by reducing the width of scanning lines.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional impregnated electrode, in which (a) shows a normal impregnated electrode, (b) shows a matrix cathode, and
The figure is a sectional view of one embodiment of the impregnated electrode according to the present invention.
The figure shows the change in saturation current density over time when each of the impregnated electrodes of the gods is mounted on a color cathode ray tube. 1. Heat-resistant gold J@ (' W grain) 2. Electron-emitting material 5
．． 05 grains 4...Tun-Aimei patent attorney Junnosuke Naka

Claims (4)

[Claims] (1) Heat-resistant metal desk and Os, 1. In an impregnated cathode in which an electron-emitting substance of barium aluminate thread oxide is immersed in a two-element or multi-element porous substrate consisting of one of r, H, and u, O is added on the surface of the cathode.
An impregnated cathode characterized in that it is coated with a single-phase film made of any one of S % I-r XRu or an alloy phase film made of any combination of the above elements. (2) The impregnated cathode according to claim 1, wherein the heat-resistant metal is W. (3) Addition of any one of 0sXIr, 1(・U, or multiple elements thereof (It is 5 to 60% by weight) '1 An impregnated cathode as set forth in claim 2. (4) The thickness of the alloy phase film consisting of any one of Os, Ir, Ru, jij, or any introduction of all elements shall be 01 to 2 μm f
: An impregnated cathode according to any one of claims 1 to 3, wherein the medullary sign is a medullary feature.