JPH04342940A - Vacuum envelope - Google Patents

Abstract

PURPOSE:To provide a vacuum envelope of such a structure that leak at the adhered point or generation of gas is lesser and it is applicable to a fluorescent character display tube of perfect chipless type. CONSTITUTION:A low melting joint, glass is melted, and after removal of bubbles, is solidified in a desired shaped to yield a molded glass 1. Each of such glass is interposed between a base board 2 and a side plate 3 and between the side plate 3 and a flat plate 4, and heated and melted in a high vacuum atmosphere, and the glass members are adhered with each other.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the construction of a vacuum envelope for a fluorescent display tube, and is particularly effective for chipless fluorescent display tubes.

0002

2. Description of the Related Art The process of manufacturing an envelope for a fluorescent display tube includes a sealing process and a sealing process. The sealing process is a process of assembling an envelope by bonding glass members together in air or an inert atmosphere. The sealing process is a process of evacuating the inside of the envelope assembled in the sealing process to a high vacuum state to form a vacuum envelope.

[0003] In either process, a glass solder is used to bond glass members together or to bond glass members and metal members. Glass solder is a viscous paste made by adding an organic solvent to frit glass, which is made by processing low-melting-point glass into powder, and is applied to the bonded parts using a screen printing method.

0004

[Problems to be Solved by the Invention] Glass solders that have been used in the past contain a large number of air bubbles. These bubbles consist of air attached to the frit glass or air mixed in during the manufacturing process. Since the glass solder is in the form of a paste with a certain viscosity, the air contained inside is difficult to escape.

[0005] If the envelope is sealed using such a glass solder that contains air, these air bubbles will come out when creating a vacuum during the sealing process, so it is necessary to evacuate until a high vacuum is achieved. There were problems such as it took a long time to complete the process.

For example, in the sealing process of a chipless fluorescent display tube with a lid, the glass solder is used to seal the exhaust hole with a metal lid. However, in addition to the problem that air bubbles are generated from the glass solder in the vacuum chamber and the degree of vacuum is lowered, there is also the problem that the glass solder scatters. Therefore, the glass solder is calcined in advance to release the gas, but if the temperature of the calcining is below the softening point, it is difficult for the air to escape. If the air left inside the glass solder leaks after sealing, the vacuum inside the envelope will drop, and the cathode, phosphor, etc. will be affected by oxidation and other negative effects, reducing the reliability of the fluorescent display tube. Sometimes there were problems with storage.

Furthermore, in a completely chipless fluorescent display tube that has no exhaust pipe or exhaust hole, the container portion is bonded to the outer peripheral edge of the substrate while heating in a high vacuum atmosphere, and sealing and sealing are performed simultaneously. It forms a vacuum envelope. For this reason, since the glass solder is applied to the entire surface of the opening end of the container, a large amount of the glass solder is used, and a large amount of air is mixed in. Therefore, the various problems mentioned above are particularly noticeable.

[0008] In the above-mentioned pre-firing for degassing, the frit glass of the glass solder is heated to a temperature higher than the softening point of
Although it is preferable to heat the substrate to 50 to 600° C., heating to such a temperature will oxidize the metal parts, filaments, phosphor layer, etc. on the substrate. Therefore, when such heating is performed in the sealing process, an inert gas atmosphere is created in the furnace to prevent oxidation of the parts. Therefore, air bubbles are not pulled out using a vacuum pump while heating, and the sealing process is performed in a state where air is difficult to escape from the glass solder. For this reason, it is not possible to prevent the generation of bubbles in the subsequent sealing process.

It is an object of the present invention to provide a vacuum envelope constructed of bubble-free, low-melting glass.

0010

[Means for Solving the Problems] The vacuum envelope of the present invention includes:
The vacuum envelope is characterized in that the glass members constituting the vacuum envelope are assembled through molded glass formed by melting low-melting glass.

Further, according to the present invention, in a flat box-shaped vacuum envelope in which a substrate and a flat plate facing the substrate are integrally assembled via a frame-shaped spacer member, the spacer member is made of a material having a low melting point. It may be constructed of molded glass that is formed into a frame shape by melting glass.

0012

[Operation] Molded glass is a member made by melting low-melting glass and solidifying it into a predetermined shape, so it contains almost no air bubbles. Therefore, if a vacuum envelope is assembled via this molded glass or a spacer member made of the molded glass, almost no air bubbles will be generated during the sealing or sealing process.

[0013]

[Example] The molded glass applied to the example of the present invention is
70% low melting point glass with a softening point of 450-600℃
It is heated to a high temperature of 0 to 800°C to bring it into a molten state to lower its viscosity, and after sufficiently defoaming, it is molded into an arbitrary shape. Note that when defoaming is performed, the appearance becomes transparent.

[0014] This molded glass is interposed as a single component between the glass members constituting the vacuum envelope, for example between the substrate and the container. After sealing, the glass members are hermetically bonded together.

The shape of the molded glass may be determined, for example, in accordance with the shape of the sealed portion of the vacuum envelope. For example, FIG. 2 shows a round bar shaped shaped glass 1a, FIG. 3 shows an elongated thin plate shaped shaped glass 1b, and FIG. 4 shows a frame shaped shaped glass 1c.

The manufacturing process of a vacuum envelope using such shaped glass 1 will be explained with reference to FIG. 1. However, in FIG. 1, the internal structure of the vacuum envelope is omitted.

First, a wiring conductor and an anode conductor made of an Al thin film are formed on the substrate 2 by photolithography. The wiring conductor except the anode conductor is covered with an insulating layer, and a phosphor layer is deposited on the anode conductor to form an anode.

On the substrate 2, a mesh-like control electrode is provided above the phosphor layer using a conductive adhesive. Furthermore, a filament-shaped cathode is stretched above it.

A frame-shaped side plate 3 is installed on the periphery of the upper surface of the substrate 2 with the molded glass 1 made of sufficiently defoamed low melting point glass interposed therebetween. Further, a flat plate 4 is installed on the open upper end surface of the frame-shaped side plate 3 via the same molded glass 1.

Using a suitable jig capable of applying pressure to the flat plate 4 and the substrate 2 in a direction perpendicular to the surfaces, the envelope is held in a floating state in a box shape. This is housed in a vacuum chamber and evacuated under a high vacuum atmosphere of 10-6 Torr or higher. Thereafter, after disassembling the cathode, the inside of the vacuum chamber is heated at 450 to 600°C to melt the molded glass 1, and pressure is applied from above and below using the jig to form the flat plate 4, the substrate 2, and the side plate 3. are adhered to each other to complete the vacuum envelope 5.

FIG. 5 is a perspective view showing a molded glass 10 according to another embodiment. This molded glass 10 is obtained by melting low-melting glass, sufficiently degassing it, and then molding it into a frame shape having a height required as a side plate.

That is, this molded glass 10 is a member interposed between the substrate 2 and the flat plate 4 as a spacer member. Specifically, this frame-shaped molded glass 10 is placed on the substrate 2, and the flat plate 4 is further placed on the upper surface thereof. Then, using an appropriate jig, the substrate 2 and the flat plate 4 are pressed against the molded glass 10 while controlling the molded glass 10 so that it does not become thinner than a certain thickness.

[0023] This is housed in a vacuum chamber, and the inside of the chamber is evacuated. When the inside of the vacuum chamber becomes a high vacuum state, the inside of the chamber is heated to soften the molded glass 10, and the molded glass 10, the flat plate 4, and the substrate 2 are bonded together. In the state where the molded glass 10 is softened, the flat plate 4
The molded glass 10 is sandwiched between the substrates 2 from above and below, but since the molded glass 10 is regulated by the jig, the molded glass 10 is not crushed indefinitely, and a constant thickness as a spacer member is ensured.

In the above embodiment, a jig for pressing the flat plate 4 and the substrate 2 was used as a stopper-like regulating member so that the softened molded glass 10 could have a constant thickness as a spacer member. Means may also be used. for example,
Beads of a certain particle size made of a material that does not melt at the melting temperature of low melting point glass may be placed inside the shaped glass 10.

[0025]

According to the present invention, since the glass members of the vacuum envelope are bonded using molded glass formed by melting low melting point glass, the following effects can be obtained. (1) Since there are no air bubbles in the molded glass that forms the bonded portion of the vacuum envelope, leakage from the bonded portion is reduced. (2) Since there were no air bubbles in the bonded area and it was made entirely of glass components, the bonding strength was increased. (3) We were able to put a completely chipless vacuum envelope into practical use. (4) When applied to a completely chipless vacuum envelope, the sealing process, exhaust process, and sealing process, which were conventionally separate processes, can be performed in one process, simplifying the process.

[Brief explanation of drawings]

FIG. 1 is a sectional view omitting the internal structure of one embodiment.

FIG. 2 is an example of a shape of molded glass used in one embodiment.

FIG. 3 is an example of a shape of molded glass used in one embodiment.

FIG. 4 is an example of a shape of molded glass used in one embodiment.

FIG. 5 is a perspective view showing a molded glass as a spacer member used in another embodiment.

[Explanation of symbols]

1, 1a, 1b, 1c, 10 Molded glass 2 Substrate 3 as a glass member Side plate 4 as a glass member Flat plate 5 as a glass member Vacuum envelope

Claims (2)

[Claims] 1. A vacuum envelope characterized in that the glass members constituting the vacuum envelope are assembled through molded glass formed by melting low melting point glass. 2. A flat box-shaped vacuum envelope in which a substrate and a flat plate facing the substrate are integrally assembled via a frame-shaped spacer member, wherein the spacer member melts low-melting glass to form a frame. A vacuum envelope characterized by being made of molded glass formed into a shape.