JPH0246637A - Fluorescent character display tube - Google Patents

Abstract

PURPOSE:To make it possible to obtain a fluorescent character display tube of excellent emission characteristics and with no insulation defect on the interface between the insulating layer and the underlying electrode layer by specifying the composition of water glass to be used for graphite paste. CONSTITUTION:The anode substrate of a fluorescent character display tube consists of a soda glass plate 1 on which silver wiring 2, insulating layer 4, through hole dots 3, underlying electrode layer 5 and phosphor layer 6 are laminated. Here, the composition of the water glass to be used for graphite paste is specified to be 11-19wt.% of Na2O, 15-28wt.% of K2O, 1.0-1.5wt.% of Li2O and 65-70wt.% of SiO2. Thereby the baking temperature of the substrate can be lowered by 50-100 deg.C than that of conventional one. It can be baked in the range of 500-550 deg.C. Thereby the insulation of the interface between the insulating layer and the underlying electrode layer can be improved to obtain a fluorescent character display tube of excellent emission characteristics.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a fluorescent display tube.

[Conventional technology]

Fluorescent display tubes perform light-emitting display by accelerating and controlling electrons emitted from a cathode using a control electrode and causing them to strike a phosphor layer in an anode.
It has been used in a wide range of applications, including audio, and recently graphic displays and car displays.

Conventionally, the anode substrate of this type of fluorescent display tube has a laminated structure as shown in FIG. That is, soda glass 1
Copper wiring (or AJI wiring) 2 and an insulating layer 14 on top. Through-hold 3. Base electrode layer 15. A phosphor layer 6 is laminated.

Each layer is formed by screen printing, and fired at a firing temperature that provides the best vitrification. For example, conventionally, Ag powder and B20, -3i○2-pbo
Ag paste mainly composed of glass, Fe2O3 pigment and B20. -8i02-An insulating paste containing PbO as a main component.

Graphite powder B 203S i O2P b O
through-hold kit mainly composed of graphite powder and water glass, a base electrode mainly composed of graphite powder and water glass, and a phosphor paste mainly composed of phosphor and cellulose binder.
Each was fired in a temperature range of 0 to 600°C.

In particular, the materials of the base electrode layer 15 include graphite powder, alumina sol, and sodium silicate.

It was formed by making a paste of water glass made of potassium silicate, water, and a solvent such as glycerin as a binder.

[Problem to be solved by the invention]

In the conventional substrate manufacturing method described above, since the firing temperatures of the insulating layer and the base electrode layer are very close to each other, air bubbles 7 are generated at the interface between the two layers as shown in FIG. 4, which causes insulation failure. There was a drawback.

In addition, the graphite powder in the base electrode layer 5 undergoes surface oxidation at temperatures above 550° C., increasing conductive resistance and increasing gas in the vacuum tube, which has a negative effect on emission characteristics.

An object of the present invention is to provide a fluorescent display tube that is free from insulation defects at the interface between an insulating layer and a base electrode layer and has excellent emission characteristics.

[Means to solve the problem]

The present invention provides a fluorescent display tube that emits light by causing electrons emitted from a cathode to collide with a phosphor layer on an anode substrate, in which the glass component of the base electrode of the phosphor layer is sodium silicate,
Contains three components of potassium silicate and lithium silicate, and the composition ratio in the glass component of the base electrode layer is Na2O...11
~19% by weight, K2O...15-18% by weight, Li2O...
1.0-1., 5% by weight, SiO2...65-70% by weight
and the firing temperature of the base electrode layer is 500 to 5
The temperature is 50°C.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

Fig. 1 is a sectional view of the main part of the anode substrate of the fluorescent display tube according to the first embodiment of the present invention, and Fig. 2 shows the relationship between brightness and high temperature operating time, showing the life test results of water glass having the composition shown in Table 1. FIG. 3 is a characteristic diagram of the relationship between heat generation, endotherm, and temperature, showing the results of thermal analysis of water glass having the composition shown in Table 1.

First, in the first example, the relationship between the composition of water glass and a life test was investigated in order to investigate the influence of the composition of water glass on the characteristics of a fluorescent display tube.

The water glass composition is Na2O, 20. L i20°S
Nine types of water glasses were prepared so that the weight % ratio of i02 was as shown in Table 1. 5 parts by weight of these nine types of water glass in solid content, 30 parts by weight of graphite powder (natural graphite),
25 parts by weight of alumina sol, 3 parts by weight of sodium linoleate, water and glycerin Using this graphite paste, a base electrode layer was formed by screen printing, and after firing at 550°C, the base electrode layer was formed. A phosphor layer 6 was formed by firing, and an anode substrate was produced.

This anode substrate is assembled and sealed using a predetermined method.

By performing evacuation, a fluorescent display tube was obtained. FIG. 2 shows the results of evaluating high-temperature life characteristics using the nine types of fluorescent display tubes obtained in this way.

It has been known that this lifespan characteristic is greatly influenced by the water glass composition shown in Table 1, but until now it has been unclear how water glass affects the lifespan characteristic.

It was known that the lifetime characteristics were influenced by the firing temperature of the graphite paste within the film. Therefore, the first
Thermal analysis of the nine types of water glass shown in the table was conducted to examine how the water glass changes depending on the firing temperature, and the results are shown in Figure 3. Figure 3 shows 80°C at a rate of 10°C/i.
This shows the results of differential thermal analysis when the temperature was raised to 0°C, and each chart number corresponds to the number in Table 1.

As a result of differential thermal analysis, it was found that the vitrification temperature and the waveform of the exothermic peak differ greatly depending on the composition of the water glass.

In the first implementation, for example, as seen in the third design ■,
The glass composition is Na2O...18% by weight.

K2O...15% by weight, Li2O...1.1% by weight.

When SiO□...65.9% by weight, this vitrification temperature is 50 to 100°C higher than the conventional water glass bottle shown in Figure 3.
We confirmed the phenomenon that as the temperature decreases, the exothermic peak waveform becomes sharper and the degree of vitrification (crystallinity) increases.

Based on the results of such differential thermal analysis, looking at the high-temperature life characteristics shown in Figure 2, we can see that the characteristics are good when the water glass composition is in NIL ■ and ■ in Table 1. Ta.

In addition, when the cross-sectional state of the anode substrate was confirmed using an SEM, as shown in FIG.
No bubbles were observed.

As a result, it was thought that the insulation properties would be improved because there would be no interfacial foaming between the insulating layer and the underlying electrode layer, which was seen in the past.
The insulation properties of the conventional graphite paste and the graphite paste of the first example were compared. The insulating layer in this case was set to 20 μm, which is 1/2 the normal thickness, in order to strictly evaluate the insulation properties of both.

As a result, as shown in Table 2, it was confirmed that the insulation properties were much improved compared to conventional products.

As mentioned above, the graphite paste of the first example can improve high-temperature life characteristics and insulation properties by considering the composition of water glass, and can be fired at a temperature 30°C lower than conventional ones. did it.

Next, a second example in which the graphite paste is fired at a temperature of 500° C. will be described.

The water glass composition was as shown in Table 1 shown in the first example, and a graphite paste was prepared in the same manner as in the first example. Using this graphite paste, a base electrode layer was formed by screen printing and fired at 500°C, and a phosphor paste was also screen printed thereon and fired at 490°C to produce an anode substrate.

A fluorescent display tube was obtained by assembling, enclosing, and evacuating this anode substrate according to a predetermined method.

The fluorescent display tube obtained in this way has high temperature life characteristics,
As a result of evaluating the insulation properties, as seen in the first example, the combination of 隘 (■) and ARASHI (■) was the best.

Above is the first part. As a result of further conducting the same study as in the second example regarding the composition of water glass, we found that the composition of water glass was
2O...11-19% by weight, 20-15-18% by weight,
Li20-...1.0-1.5% by weight, SiO2...65
When the amount was 70% by weight, the same effects and actions as in the first and second embodiments were obtained.

〔Effect of the invention〕

As explained above, in the present invention, the composition of the water glass used for Graffito paste is Na2O...11 to 19% by weight,
and O...15 to 18% by weight.

Li2O...1.0-1.5% by weight, SiO2...65-7
By setting it to 0% by weight, the firing temperature is 5% compared to the conventional method.
It is possible to perform firing in the range of 500 to 550°C, which is 0 to 100°C lower, and has the effect of improving life characteristics and insulation properties.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the main part of the anode substrate of the fluorescent display tube according to the first embodiment of the present invention, and Fig. 2 shows the relationship between brightness and high temperature operating time, showing the life test results of water glass having the composition shown in Table 1. Figure 3 is a characteristic diagram showing the relationship between heat generation, heat absorption and temperature, showing the results of thermal analysis of water glass having the composition shown in Table 1. Figure 4 is a diagram showing the main parts of an example of the anode substrate of a conventional fluorescent display tube. FIG. DESCRIPTION OF SYMBOLS 1...soda glass, 2...silver wiring, 3...through-hole socket, 4...insulating layer, 5...base electrode layer, 6...phosphor layer, 7...
Bubbles, 14...Insulating layer, 15... Base electrode layer. electrode layer.

Claims (1)

[Claims] In a fluorescent display tube that emits light by causing electrons emitted from a cathode to strike a phosphor layer on an anode substrate, the glass component of the base electrode of the phosphor layer is one of sodium silicate, potassium silicate, and lithium silicate. The composition ratio in the glass component of the base electrode layer is Na_2O...11 to 19% by weight, K_2O...15 to 18% by weight, Li_2O...1.
0 to 1.5% by weight, SiO_2...65 to 70% by weight, and the firing temperature of the base electrode layer is 500 to 550% by weight.
A fluorescent display tube characterized by a temperature of ℃.