JPH05101795A - Fluorescent display tube - Google Patents

Abstract

PURPOSE:To form a fine pattern being excellent in printability, and suppress the generation of harmful gas by constituting an anode and a back face electrode using graphite and low melting point glass including the respective specific wt.% of B2O3, ZnO and SiO2. CONSTITUTION:After a wiring layer 2, via Ag paste by means of a screen printing method, and a insulating layer 3, whose main component is low melting point glass, is formed on a glass base 1, an anode 4 is formed via oily carbon paste, and is fired at a fixed temperature in an air atmosphere. The oily carbon paste is composed of 40wt.% of graphite, 40wt.% of B2O3-ZnO-SiO2 low melting point glass (B2O3 50%, ZnO 35%, SiO2 10%, Al2O3 5%), and 20wt.% of vehicle (ethyl cellulose + butyl carbitol acetate). After a fluorescent material layer 5, being composed of ZnO:Zn, is formed on the anode 4, a grid 7 and a cathode 8 are established. Thereby it is possible to obtain excellent rising characteristics of a grid current against a filament current after fading.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent display tube,
In particular, the present invention relates to a fluorescent display tube in which an anode, a back electrode, etc. are formed of a carbon layer.

[0002]

2. Description of the Related Art Conventionally, a fluorescent display tube has a structure in which the light emission of a phosphor layer 5 is observed through a transparent face glass 9 as shown in FIG. 1, and as shown in FIG. There is a structure in which the transparent anode substrate 6 is observed through.

In the structure shown in FIG. 1, an Ag wiring layer 2 having a predetermined pattern and an insulating layer 3 made of low melting point glass are formed on a glass substrate 1 made of, for example, soda lime glass by a screen printing method. An anode 4 having a predetermined pattern is formed on the surface of the insulating layer 3 through the through hole 3a so as to be electrically connected to the wiring layer 2 by screen printing and firing of carbon paste. An electron beam phosphor layer 5 is deposited and formed. On the anode substrate 6 thus formed, the grid 7 and the cathode (W thin wire (B
a, Sr, Ca) O coated filamentary oxide cathode) 8 is further provided, and a vacuum container is formed by sealing with a transparent face glass 9 by a low melting point glass (not shown). .. Further, in this structural bulb, the inner surface of the face glass 9 is covered with a nesa film 10 for the purpose of blocking an external electric field.

In the structure shown in FIG. 4, the wiring layer 2 and the transparent anode 4 are formed on the glass substrate 1 such as soda lime glass by a photo-etching method of an Al thin film,
Then, the insulating layer 3 and the phosphor layer 5 are formed by screen printing.
And are sequentially formed. After the grid 7 and the cathode 8 are provided, the face glass 9 is sealed and a vacuum container is formed.
Further, in the tube having this structure, in order to prevent the light emitted from the phosphor layer 5 from being reflected on the inner surface of the face glass 9, a back electrode 11 made of a carbon layer having a low reflectance is provided instead of the nesa film. ing.

The carbon paste for forming the anode 4 in FIG. 1 and the carbon paste for forming the back electrode 11 in FIG. 4 are roughly classified into two types. One is a water-based carbon paste such as GA-135 (manufactured by Hitachi Powder Metallurgy) containing graphite and water glass as main components, and the other is C-2F (manufactured by Noritake) or F-525W.
Graphite and Pb-B ₂ O ₃ -Si such as (Nippon Graphite Industries, Ltd.)
It is an oily carbon paste containing O ₂ -based low melting point glass as a main component.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention A conventional fluorescent display tube using an aqueous carbon paste or an oily carbon paste has the following problems. When an aqueous carbon paste is used, printability is poor and it is difficult to form a fine pattern. A large amount of gas is released after being made into a tube, and particularly when the tube is left unlit for a long period of time, the brightness of the zinc oxide phosphor is likely to decrease due to gas adsorption. The adhesion of the phosphor to the carbon layer is weak, and peeling and low-luminance light emission easily occur. There was such a problem. As an attempt to solve such a problem, for example, Japanese Patent Laid-Open No. 64-24345 proposes a water-based carbon paste containing an alkyl silicate, but it is still a sufficient solution such as poor printability. I haven't arrived. On the other hand, when the oily carbon paste is used, the above-mentioned problems (1) to (3) of the water-based carbon paste are small, but there is a problem that harmful gas is released to the cathode in the sealing process and the exhaust process to deteriorate it. ..

Therefore, the present invention has been made in order to solve the above-mentioned conventional problems, and an object thereof is to form an anode and a back electrode with high precision, and to improve the emission characteristics of a phosphor and the electron emission capability of a cathode. To provide an excellent fluorescent display tube.

[0008]

In order to achieve such an object, the present invention provides at least 30 to 50% by weight of B ₂
The low melting point glass containing O ₃ , 20 to 40% by weight of ZnO and 10 to 20% by weight of SiO ₂ is used to form the anode and the back electrode.

[0009]

In the present invention, the printability is good, a fine pattern can be formed, the generation of harmful gas is suppressed, and the deterioration of the performance of the cathode and the phosphor is suppressed.

[0010]

Embodiments of the present invention will be described in detail below with reference to the drawings. (Example 1) Similar to FIG. 1, a wiring layer 2 made of Ag paste and an insulating layer 3 containing low melting point glass as a main component were formed on a glass substrate 1 by a screen printing method, and then an oily carbon paste having the following composition was formed. The anode 4 was formed by and the firing was performed at about 580 ° C. in an air atmosphere. Carbon paste composition Graphite: 40% by weight B ₂ O ₃ —ZnO—SiO ₂ system low melting point glass: 40% by weight (B ₂ O ₃ 50%, ZnO 35%, SiO ₂ 10%, Al ₂ O ₃ 5%) Vehicle: 20 wt% (Ethyl cellulose + butyl carbitol acetate) After a phosphor layer 5 made of ZnO: Zn is deposited on the anode 4, a grid 7 and a cathode 8 are formed. Was provided, and after the face glass 9 was sealed, it was evacuated. The rising characteristics of the grid current with respect to the filament current after aging are shown in FIG. In Figure 2, data for three samples
I, II, and III are shown.

FIG. 3 shows the rising characteristics of the grid current with respect to the filament current in a tube using a conventional oily carbon paste mainly composed of graphite and PbO-B ₂ O ₃ -SiO ₂ type low melting point glass. 4 and FIG. 4 also shows data IV, V, VI for three samples. As is clear from a comparison of these characteristics, the tube according to the present example has obtained a saturated emission amount that is higher by one digit. Also, regarding the emission characteristics of the phosphor, PbO-B
_The average brightness of the tube using the ₂ O ₃ —SiO ₂ -based low melting point glass was 330 fL, whereas the average brightness of the tube according to this example was 390 fL. This is considered to be because the fluorescent display tube according to the present embodiment emits less gas from the carbon layer and reduces the contamination of the phosphor, as can be seen from the difference in the cathode characteristics. Further, when the water-based carbon paste was used, no decrease in brightness of the zinc oxide phosphor due to gas adsorption did not occur when left for a long time in a non-lighting state, which is a problem. In addition, regarding the printability, it became possible to print a fine pattern of the same degree as the conventional oily carbon paste.

(Embodiment 2) Similar to FIG. 4, after forming the wiring layer 2 and the transparent anode 4 on the glass substrate 1 by the photo-etching method of the Al thin film, the insulating layer 3 and ( ZnCdS: Ag + In ₂ O ₃ , emission color: red)
And a phosphor layer 5 composed of This anode substrate 6
A grid 7 and a cathode 8 are provided on the top. On the other hand, a back electrode 11 made of an oily carbon paste having the following composition was formed on the inner surface of the face glass 9 and fired at about 600 ° C. Carbon paste composition Graphite: 40% by weight B ₂ O ₃ —ZnO—SiO ₂ system low melting point glass: 40% by weight (B ₂ O ₃ 35%, ZnO 30%, SiO ₂ 20%, BaO 10%, Al ₂ O ₃ 5%) Vehicle: 20% by weight (ethyl cellulose + butyl carbitol acetate) The completed anode substrate 6 and face glass 9 are sealed with a low melting point glass, exhausted, The characteristics were measured after aging.

The fluorescent display tube thus manufactured is
It was possible to operate at a cathode temperature about 40% lower than that of a conventional bulb using an oily carbon paste containing graphite and PbO—B ₂ O ₃ —SiO ₂ -based low melting point glass as main components. Also, regarding the emission characteristics of the phosphor, PbO-B ₂
While the brightness of the tube using the O ₃ —SiO ₂ -based low melting point glass is 31 fL (average value of 5 samples), the tube according to the present example has 35 fL (average of 5 samples similarly). Value) was extremely good.

The reason why the cathode characteristics are improved by using the B ₂ O ₃ -ZnO-SiO ₂ -based low melting glass instead of the conventional PbO-B ₂ O ₃ -SiO ₂ -based low melting glass is clear. However, I guess it is as follows. That is, in the former case, P in the low melting point glass is used in the sealing process and the exhaust process.
It is considered that, while bO is reduced by the reaction with graphite and released, it deteriorates the cathode, whereas the latter does not contain PbO, and therefore the harmful gas emission to the cathode is small.

In the present invention, B in the low melting point glass is₂O₃，
ZnO, SiO₂ 30 to 50% by weight, 2
Limited to the range of 0-40% by weight, 10-20% by weight
Is due to restrictions such as softening point, expansion coefficient and water resistance.
is there. Ie B₂O₃If the content is less than 30%, the soft
It has a high conversion point and is usually used as a substrate for fluorescent display tubes.
Difficult to use in soda lime glass. On the contrary, 50%
If it exceeds, problems such as deterioration of water resistance occur. Well
ZnO and SiO₂ 40% and 20% respectively
Beyond that, soda lime glass rises in softening point and expansion coefficient
It becomes difficult to adjust to
When it is less than 20% or 10%, B is relatively ₂O₃Will increase
Therefore, problems such as water resistance occur, soda lime glass
Is difficult to use.

In the above-mentioned embodiment, B ₂ O ₃ --ZnO--
The reason why BaO and Al ₂ O ₃ are contained in the SiO ₂ -based low melting point glass is to improve water resistance and adjust the expansion coefficient.

[0017]

As described above, according to the present invention,
An extremely excellent effect as described below can be obtained. Since the carbon layer can be formed by the oily paste, the printability is good and a fine pattern can be formed. The gas emission after tube formation is small, and the brightness of the zinc oxide phosphor does not decrease when left for a long time in a non-lighting state. Adhesive strength of the phosphor to the carbon layer is strong, and peeling and low-luminance light emission are unlikely to occur. Since no harmful gas is emitted to the cathode in the sealing process and the exhaust process, a cathode having a high electron emission capability can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an essential part showing a configuration according to an embodiment of a fluorescent display tube according to the present invention.

FIG. 2 is a diagram showing a rising characteristic of a grid current with respect to a filament current of a fluorescent display according to the present invention.

FIG. 3 is a diagram showing a rising characteristic of a grid current with respect to a filament current of a conventional fluorescent display tube.

FIG. 4 is a sectional view of an essential part showing the configuration of another embodiment of the fluorescent display tube according to the present invention.

[Explanation of reference numerals] 1 glass substrate 2 wiring layer 3 insulating layer 4 anode 5 phosphor layer 6 anode substrate 7 grid 8 cathode 9 face glass 10 nesa film 11 back electrode

Claims (1)

[Claims] 1. A fluorescent display tube in which an anode or a back electrode is formed of a carbon layer containing graphite and low melting point glass as main components, wherein the low melting point glass is at least 3
A fluorescent display tube comprising 0 to 50% by weight of B ₂ O ₃ , 20 to 40% by weight of ZnO and 10 to 20% by weight of SiO ₂ .