JPS6353831A - Manufacture of cathode - Google Patents

Abstract

PURPOSE:To lower a discharge voltage, by thermally decomposing alkaline earth metal azide, which is sticking on a conductor, in a vacuum so as to precipitate alkaline earth metal, and thereafter oxidizing this alkaline earth metal in an oxygenic atmosphere. CONSTITUTION:A gas discharge type display panel, in which alkaline earth metal azide is sticking on a cathode conductor, is assembled by the use of a transparent surface plate 10 and a substrate 20, and is assumptively fixed and equipped with a frit glass 40 on the periphery. The panel assembled in this way is put between plates 50 for mounting the panel and fixed in a vacuum container 70 having an exhaustion device. Then, valves B1 and B6 are opened to exhaust the panel and the container 70 so that their insides are highly vacuumized. Successively, a temperature of the panel is raised, then the azide is thermally decomposed, and alkaline earth metal is thus precipitated, and, at the same time, a process of sealing the panel by frit 40 is completed. Then, after the valves B1 and B6 are closed, and a valved B4 is opened, O2 is introduced into the panel so that the alkaline earth metal is oxidized. Hence, a work function of the panel's cathode and discharge voltage of the panel can be lowered.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method of forming a cathode as an electron source.

In particular, the present invention relates to a method for forming an alkaline earth metal oxide cathode suitable as a cathode for a DC gas discharge type display panel that displays characters, images, etc.

[Conventional technology]

Conventional cathodes are made by thermally decomposing alkaline earth metal azides such as Ba(N3)2, which is easy to handle and has a low activation treatment temperature, in a vacuum, as described in Japanese Patent Application No. 127671/1983. (120-200C) L13a metal was precipitated and used as Ba1i. In addition, an example of the application of this Ba cathode to a DC gas discharge type display panel was published in Japanese Patent Laid-Open No. 5
It is described in Publication No. 7-87042. That is, on a glass substrate and a plurality of cathode generatrixes parallel to each other, a cathode made by printing and drying a mixture of dot-shaped K Ba (N 3) 2 and five layers of glass powder, and a surface made of a transparent glass plate. A plurality of honeycombs parallel to each other so as to be orthogonal to the cathode bus line are provided by firing AU paste,
The face plate and the substrate are overlapped via spacers having a plurality of discharge spaces corresponding to the intersection points, and a glass frit is provided around the surface. The 7 panels thus targeted were set in a vacuum container. Next, the entire panel was subjected to thermal decomposition of Ba(N3)z,
A panel with a cathode 13a is completed through melting and solidification of the glass frit and filling of a specified gas (Xe) into the panel.

FIG. 2 shows the panel temperature and the working process in backing of the panel with Ba negative images. High vacuum inside and outside the panel (';
While keeping the temperature at 10-"f:orr), the panel temperature was slowly raised from room temperature, and at 1oor (a)-(b)
Exhaust 20 etc. Further increase the temperature to 120ic~
Pyrolyze (C) (d) Ba(N3)z at 200C.

Ba metal is deposited on the cathode surface. Furthermore, while maintaining a high A air temperature (≦10-”forr) inside and outside the panel, the temperature rises until the frit glass melts (e) (450C), and when the frit glass begins to bubble (0), the inside and outside of the panel become large. Fill in a rare gas such as Ar gas to approximately atmospheric pressure. After keeping it at a high temperature until it is completely dissolved, lower the temperature too much (ω → (h), and when the glass frit completely solidifies (h) ) (approximately 200c). Next, the inside of the panel is evacuated with high N2 (~10-7 Torr).
r) Ivy state ('')Te Specified gas, for example, Xe, He, Xe mixed gas, etc. for color display, or Ne + Ar Benning gas, etc. for monochrome display, k 10 to 600 Torr. Select, encapsulate, and chip the panel.

Using this process, a high-quality J3a metal cathode can be formed, and the minimum discharge sustaining voltage when filled with Xe gas is about 90V, which is about 1/3 lower than about 250V for a Ni cathode. I was able to convert it to voltage.

[Problem that the invention seeks to solve]

The work function of the Ba cathode of the above-mentioned prior art is about 2 to 2.5e
It is V. However, when t HaCO3 etc. is thermally decomposed (approximately 1
The work function of BaO formed by
The minimum discharge sustaining voltage in the case of Xe discharge at 1.6 e V is 47 V, which is about 1/2 of that in the case of 13a, and B
No consideration was given to lowering the voltage by further oxidizing Ba produced by thermally decomposing a(N3)2 to BaO.

An object of the present invention is to reduce the voltage mentioned above.

[Failure to solve the problem]

The above purpose is to thermally decompose the azide of an alkaline earth metal such as Ba(N3)z at a low temperature (120 to 20 CI') using a temperature process as shown in Figure 1, and to remove the precipitated alkaline earth metal. By oxidation in an oxygen atmosphere, oxides of alkaline earth metals (such as BaO) are obtained and achieved.

[Effect]

The alkaline earth metal precipitated by the thermal decomposition of alkaline earth metal azide undergoes a chemical reaction in an oxygen atmosphere to generate all alkaline earth metal oxides. The reaction rate at this time depends on @ degree, the higher the temperature, the faster the reaction rate becomes.
The thickness of the oxide layer per unit time also increases. The work function of the alkaline earth metal oxide thus formed is, for example, about 1.5'eV for BaO. Other Ca0JP
It is thought that SrO also shows a similar tendency.

If you are friends or work-related, Ba will change from 2 to 2.5 eV of Ba.
It was possible to reduce the minimum discharge sustaining voltage to about 1.5 eV for O, and the minimum discharge sustaining voltage could be reduced to about 1/2, for example, from about 90 V for Ba to about 50 'ii' for BaO. Furthermore, Ne
Even when +Ara combined gas was used, the voltage could be reduced from about 80V to about 70Y.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1, 3, and 4.

FIG. 1 shows a typical panel temperature program during production of a direct current gas discharge type display panel with a BaO cathode.

The structure of the panel is as follows: 1. For example, as shown in FIG.
It is formed by printing and baking 00i1'IJi paste or the like. In addition, an alkaline earth metal azide 1 such as Ba
(N3) 2 + Ca (N+) 2 alone or a mixture thereof is mixed with 5 to 20 g of glass powder to form a paste, and a part that operates as a cathode, for example, as shown in Figure 3 (O) It is formed into a 110-karat gold dot shape using a printing technique and dried. On the other hand, a transparent face plate 1 made of glass or the like
On the back side of 0, connect multiple l″JJ poles 200 parallel to each other
A barrier 30 for forming a plurality of discharge spaces 300 is printed and dried using metal such as a glass paste, and is fired simultaneously with the anode 200.

Note that the barrier 30 may be a spacer made of glass or the like having a plurality of discharge spaces 300. Also.

In the case of color display, a phosphor is provided on the side wall of the discharge space 300, etc.

As shown in FIG. 3(a), the face plate and substrate thus produced are combined to prevent warping, and a glass frit 40 with low gas emission is placed around the surface.

Next, as shown in Figure 4, the panel assembled in this way is sandwiched between scissors 50 (the panel is attached to a plate) using a material with a large thermal conductivity coefficient such as Cu, and placed in a vacuum container equipped with an exhaust system. Fix it. In addition, at this time, the panel can be independently exhausted (connected to the exhaust pipe 60, and pulp B3, B4,
Using Bs, rare gases such as Ar are each independently injected into the cylinder G.
From l, Mano* 02 gas comes from cylinder G2, and then x
e.

) (Predetermined gases for discharge such as e+Xe and Ne+Ar can now be supplied from cylinder G3. On the other hand, the vacuum container 70 with panel gold set is also a valve) 3+t'
It was independently exhausted through *, 'i. A rare gas G+ is introduced through the pulp B2. In addition, the panel must be installed at least 1 or above or below.
Temperature control as shown in FIG. 1 can be achieved by controlling the current of the heater provided in the chamber. Incidentally, it is also possible, of course, to perform temperature control as shown in FIG. 1 by heating the entire vacuum container 70.

Next, the operation of this device will be explained according to the temperature program shown in FIG. First, pulp B1 and Bat are opened and the inside of the panel and the inside of the vacuum container 70 are evacuated to high vacuum (≦10-
6□l'orr). Next, increase the temperature of the panel by 1
Gradually raise the temperature to 00C <a> and keep at this temperature for about 1 hour to decompose and exhaust H2O etc. (b). Furthermore, while maintaining a high vacuum (≦10-”porr), the temperature is slowly raised (C).Thermal decomposition of alkaline earth metal azide begins at about 1000C, and it is kept at about 200C for about 1 hour until completely reached. Precipitate alkaline earth metals (d).In addition, the inside of the panel is particularly kept under high vacuum (≦10”’ Tor
Raise the temperature while maintaining the temperature at 450C, and the glass frit provided around the panel begins to melt and bubbles begin to form (e). After a while (about 10 minutes), close valves Bl and 86, and gradually close valve 81.
, open B3 and introduce a rare gas such as Ar.

Introduce water until it reaches atmospheric pressure (f). In this way, bubbling of the glass frit is suppressed, and the sealing by the glass frit becomes airtight, making it possible to withstand high vacuum. After maintaining this state for about 1 hour (g)
, gradually lowering the temperature only.

When the temperature reaches about 200C, the glass frit completely solidifies (h). Next, close the valve Bz and open the pulp B6 (h), and heat and exhaust the inside of the panel to a high vacuum (≦10-7 Torr).
3500). After that, close valve B6 and open valve B4 to introduce oxygen gas into the panel.
760 Torr), a chemical reaction between alkaline earth metal elements and oxygen? generate alkaline earth metal oxides. The reaction rate at this time depends on the temperature, and is accelerated at high temperatures. Next, after the oxidation reaction has progressed sufficiently and oxides have been formed, pulp B4 is closed and pulp B6 is opened, and the inside of the panel is placed under a high vacuum (≦10-7'l'orr).
Heat and exhaust to (n)→(0). Thereafter, the panel temperature is lowered to normal while maintaining a high vacuum (i). next,
Close the pulp B6 and open the valve Bs to supply the gas necessary for gas discharge, such as Xe or H for color display.
A rare gas such as e+Xe is sealed at 10 to 500 Torr. In addition, for monochrome display using the light emission itself of discharge, N e + Ar etc. should be set at 100 to 600 To
rr Penetrate. After introducing the required gas into the panel, the panel is chipped, resulting in a panel with a cathode consisting of an oxide of an alkaline earth metal.

Note that the time axis in FIG. 1 is just an example.

It also changes depending on the size of the panel. Further, the temperature in the process from (h) to (i) in FIG. 1 is also an example, and the temperature can be arbitrarily selected. In other words, in the case of panels, the upper limit is determined by the melting point temperature of the glass.

If there is no such restriction, higher temperatures may be used. Also.

If heating is not possible under other conditions, it may be used at room temperature, or alternatively, oxygen gas may be turned into plasma to produce an alkaline earth metal oxide.

In this explanation, we have only talked about applications in gas discharge type display panels, but for example, applications such as electron tubes (CRT, CPT, etc.)
Needless to say, it can be applied as an electron source.

〔Effect of the invention〕

According to the present invention, alkaline earth metal azides are thermally decomposed in vacuum to precipitate alkaline earth metal elements, and then chemically reacted in an oxygen atmosphere to generate alkaline earth metal oxides. By using this as an FK source, the work function can be increased, which has the effect of reducing the operating voltage, such as lowering the discharge voltage. For example, in the case of Xe discharge, 25
0v, compared to 90V of 13a cathode 1 BaO according to the present invention
The cathode can significantly reduce the resistance voltage to 50V, increasing efficiency (saving power), making it possible to use an IC for the drive circuit and extending the lifespan, and the effect is tremendous in terms of cost reduction. There is.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing all 1% J of temperature programs and functions for negative image formation according to the present invention, Fig. 2 is a diagram showing temperature programs and functions for conventional cathode formation, and Fig. 3 is an example of #ffi of a panel. FIG. 4 shown in FIG. 5 is a schematic diagram of the cathode forming apparatus of the present invention. 10... Face plate 120... Substrate, 30... Barrier,
40...Glass frit, 100...Cathode bus bar, 11
0... Alkaline earth metal oxide (initially azide)
, 200...anode, 300...discharge space 150...
・Panel mounting is a board, 60...Panel exhaust pipe, 70・
...Vacuum container. Agent Patent attorney Masaru Ogawa ('c) Mimasuhama (°6) 50 Ba, Neruzuki Raisun) 1 O and 6I-θ3 Kama Mata A groin pull

Claims (1)

[Claims] 1. A conductor is coated with an azide of an alkaline earth metal, thermally decomposed in vacuum to precipitate the alkaline earth metal, and then the alkaline earth metal is oxidized in an oxygen atmosphere. Method of forming an alkaline earth metal oxide cathode.