JPS6321882Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to the structure of a display tube with an airtight sealing structure.
In particular, it relates to flat fluorescent display tubes. Display tubes with a sealed structure, especially fluorescent display tubes, have rapidly become popular in recent years as display tubes that are easy to read and can be driven at low voltage. It has been found that current designs are not of sufficient quality for use in relatively high temperatures for equipment displays. In the following, a fluorescent display tube will be specifically explained with reference to the drawings, but the present application is not limited to fluorescent display tubes.

A conventional fluorescent display tube is manufactured, for example, as shown in Fig. 1 and Fig. 2, by processing a substrate glass 1 to make an anode substrate, and then sealing this with a cover glass 2 with a solder glass 3. Specifically, first, a power supply internal lead wire 4 is arranged on the substrate glass 1, an insulating layer 5 is placed on top of this, and the power supply lead wire 4 is sealed.
The display segments 6 are electrically connected to each other via through holes 7 provided in a part of the insulating layer 5, and are led out to an external power supply lead wire 8 via another through hole 7'. A phosphor layer 9 is then attached onto the display segments, and electrodes of a grid 10 and filaments 11 are provided to form the display segments.

Conventionally, a drawback of this type of display tube is that although there is no practical problem when operating at room temperature, insulation between the leads deteriorates when operating at high temperature for a long time. The reason for this is thought to be that because inexpensive soda glass is normally used for the substrate glass 1, Na from the substrate glass 1 diffuses into the solder glass 3 and moves as Na ions to the leads with a low potential during high-temperature operation.
It is thought that this Na ion reduces lead oxide in the solder glass 3, causing metal lead to precipitate (precipitate in a dendritic form) and cause insulation deterioration.

The purpose of the present invention is to overcome these conventional drawbacks and provide an improved means for completing display tubes for electric ovens, heaters, automobiles, and the like.

According to the present invention, a glass substrate made of soda glass and a cover glass are sealed with a sealing material through an insulating layer having an alkali content of 1% or less (by weight), and the sealing material is penetrated. A display tube is obtained, which is characterized by having lead wires that provide a lead wire. In other words, the gist of the present invention is to hide the substrate glass in areas where insulation deterioration is likely to occur with an insulating layer with an alkali content of 1% or less by weight in order to prevent the diffusion of Na from the substrate glass to the solder glass. It is.
Specifically, the effect is achieved by spreading the insulating layer more widely inside the sealing part than inside the cover glass.
Particularly, according to the present invention, there is provided a processed anode substrate in which power supply lead wiring is provided on a glass substrate, an insulating layer is formed on the lead wiring, and display segments connected to the lead wiring are formed on the insulating layer; In a fluorescent display tube in which a processed anode substrate and a cover glass forming a vacuum-tight container are sealed with solder glass with electrodes such as grids and filaments arranged inside the cover glass, the above-mentioned processed anode The alkali component content is 1% as an insulating layer formed on the substrate.
A fluorescent display tube characterized in that at least a part of the insulating layer is formed within the solder glass sealing part of the cover glass is obtained by selecting the following materials (in weight %):

Next, one embodiment of the present invention will be described. That is, FIG. 3 shows an embodiment of the present invention, in which an insulating layer 5 is widely spread over a glass substrate 1 from a point P inside the cover glass to the inside of the sealing part. The rest of the structure is the same as the conventional one, but unlike the conventional one, at least the part of the glass substrate corresponding to the solder glass 3 is covered with an insulating layer with an alkali content of 1% or less (wt%). This has the effect of preventing the diffusion of Na from the glass substrate 1 to the solder glass 3. Therefore, the conventional insulating layer 5 shown in FIGS.
(The alkaline component is about 1%) can be provided extending to the sealing area to obtain the desired effect.

For example, FIG. 4 shows the relationship between time and temperature during which the insulation resistance between the terminals, which is normally several 1000 MΩ or more, deteriorates to 100 KΩ when the display tube is operated at high temperatures.
The straight line A shows the characteristics of the display tube with the conventional structure, and the straight line B shows the characteristics of the display tube with the structure according to the present invention, and it can be seen that the structure of the present invention is superior to the conventional structure. Since the main purpose of this invention is to prevent the introduction of alkali components into the solder glass, it is necessary to reduce the alkali components in the solder glass and the alkali components in the insulating layer as much as possible. Although similar effects can be expected with up to about 1% of the alkali component in the solder glass, it is desirable that the alkali component in the solder glass should not be mixed in at all. It goes without saying that if the cover glass 2 also contains a large amount of alkaline components, it may be subjected to the same treatment as the substrate glass.

Although the present invention has been described above with reference to embodiments, it is clear that the present invention is not limited by the use or implementation shape of the display tube.

[Brief explanation of the drawing]

FIG. 1 shows a partially cutaway perspective view of a conventional display tube. FIG. 2 shows a partial sectional view of FIG. FIG. 3 shows a sectional view of a display tube according to the present invention. FIG. 4 is a graph showing a comparison of operational deterioration characteristics of insulation resistance between terminals of a conventional display tube and a display tube according to the present invention. 1...Substrate glass, 2...Cover glass, 3...
...Solder glass, 4...Internal power supply lead wire,
5... Insulating layer, 6... Display segment, 7... Through hole, 8... Lead wire for external power supply, 9...
Phosphor layer, 10...Grid, 11...Filament, P...Inner part of cover glass.

Claims (1)

[Scope of utility model registration request] A glass substrate made of soda glass and a cover glass are sealed with a sealing material through an insulating layer having an alkali component content of 1% or less (wt%), and a lead wire is provided that penetrates through the sealing material. A display tube characterized by: