JP2003151437A - Manufacturing method for fluorescent character display tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance productivity of a fluorescent character display tube. SOLUTION: This manufacturing method has an evacuating process to evacuate the inside of a vacuum chamber 1 after disposing a metallic body 20 to which an anode base 33, a filament 31 disposed apart from the anode base 33, and a grid 32 provided between the anode base 33 and the filament 31 and a metallic face 10 in the vacuum chamber 1, a filament activating process to energize the filament 31 with a prescribed voltage for a prescribed time under the evacuated condition after the evacuating process ends, and a sealing process to combine the metallic face 10 and the metallic body 20 and to weld the face jointing both of them after the filament activating process ends.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a fluorescent display tube.

[0002]

2. Description of the Related Art A fluorescent display tube is an electron tube that displays a desired pattern by causing electrons emitted from a cathode to collide with a phosphor and emit light in a vacuum container. A general fluorescent display tube is provided between an anode in which a phosphor layer is formed and deposited in an envelope kept in a vacuum, a filament cathode stretched over the anode, and between the anode and the filament cathode. The grid electrode (control electrode) is provided, and thermoelectrons emitted from the filament cathode are controlled by the grid electrode and collide with the surface of the phosphor layer to emit light by excitation.

A conventional general fluorescent display tube is a transparent face glass which covers an anode substrate having an anode having a phosphor layer formed on a glass substrate and a grid and a filament which are spaced from each other on the anode substrate. An envelope is constituted by and the joint between the anode substrate and the face glass is hermetically sealed with a low melting point glass. The process of forming a conventional envelope will be described below. The conventional manufacturing process for forming an envelope includes a sealing process in which an anode substrate and a face glass are sealed with a low-melting glass to form an envelope, an exhaust process for evacuating the inside of the envelope, and a filament It comprises a filament activation step for activation and a sealing step for shielding the envelope from the outside air.

In the sealing step, an anode substrate having a filament and a grid attached thereto and a face glass are fixed with a jig with a low melting point glass sandwiched between them on a joint surface, and then they are fixed in a continuous electric furnace in an inert gas atmosphere. By heating for a predetermined time depending on the temperature conditions, the anode substrate and the face glass are sealed to form an envelope. In the exhaust process, the exhaust pipe attached to the face glass is connected to a vacuum exhaust system, and the envelope is degassed for a predetermined time while heating the envelope to degas the inside of the envelope and achieve a predetermined degree of vacuum. To do.

In the filament activation step, after the envelope is evacuated under a predetermined condition, the filament is heated at a predetermined voltage for a predetermined time in an evacuated state so that the alkaline earth metal carbonate applied to the filament is removed. While thermally decomposing into an oxide, the organic binder used for coating is decomposed and vaporized to activate the cathode. In the sealing process,
After melting the exhaust pipe with a gas burner and sealing it, the exhaust pipe on the outside air side is cut to shut off the envelope from the outside air.

[0006]

However, in the conventional manufacturing method, since the mating surfaces of the anode substrate and the face glass are bonded with the low melting point glass in order to form the envelope in the sealing step, these Was required to be heated to the melting temperature of the low melting point glass, and it took time to manufacture.
Further, in the exhaust process, exhaust is conducted through an exhaust pipe attached to the face glass, so that the exhaust conductance is small and it takes time to exhaust. As described above, in the conventional manufacturing method, it is not possible to expect a great improvement in productivity because the sealing process and the exhaust process take time. The present invention has been made to solve the above-described problems, and provides a manufacturing method that shortens the time required for the sealing step and the exhaust step in the manufacturing process of a fluorescent display tube and greatly improves the productivity. The purpose is to

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a fluorescent display tube in which an anode substrate, a grid, and a filament coated with an electron-emitting material are housed in an envelope consisting of a metal face having a display window and a metal body. A metal body having a positive electrode substrate, a filament arranged apart from the positive electrode substrate, and a grid provided between the positive electrode substrate and the filament in a vacuum chamber; After arranging the face, an exhaust step of exhausting the inside of the vacuum chamber to a vacuum, a filament activation step of energizing the filament with a predetermined voltage for a predetermined time in the exhausted state after the exhaust step, and after the filament activation step, It is characterized by having a sealing process of combining a metal face and a metal body and welding the mating surfaces of both. Here, an example of the sealing step is welding with an electron beam.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, an apparatus for manufacturing a fluorescent display tube according to the embodiment of the present invention will be described. Figure 1
It is explanatory drawing which shows the structure of the manufacturing apparatus of the fluorescent display tube in this Embodiment. This manufacturing apparatus includes a vacuum chamber 1 as shown in FIG.
Inside of, the matching mechanism 2, the heating mechanism 3, and the energizing mechanism 4
And the electron beam welding mechanism 5 are arranged. Also,
The vacuum chamber 1 is connected to a vacuum exhaust unit (not shown) through an exhaust pipe 6, and the vacuum exhaust unit 10 ^-3
It is configured to be able to exhaust up to a pressure of about 10 ⁻⁵ Pa.

The alignment mechanism 2 has a metal face attachment portion 2a and a metal body attachment portion 2b for holding the metal face 10 and the metal body 20 constituting the envelope of the fluorescent display tube so that their mating surfaces face each other. However, it has a function of moving the metal face 10 so that the mating surfaces contact each other. In addition, the matching mechanism 2 has a conductive portion connected to the ground for grounding the metal face 10 and the metal body 20. The metal face 10 is formed by processing a metal plate into a cap shape and then opening a top portion to form a display window. A transparent glass plate 11 is fitted into the display window, and the low melting point glass 12 is used to form the metal and the glass. The mating surfaces are bonded together and hermetically sealed.

The metal body 20 is formed by penetrating a plurality of lead pins 21 on a metal flat plate. In this case, the penetrating portion is formed of a hermetic seal 22 in order to insulate the lead pin 21 from the airtight seal. The amount of constituent materials of the metal face 10 and the metal body 20 is iron, 426.
Any of alloys, titanium and kovar can be used. In this embodiment, the metal face 10 has 426
An alloy was used, and iron was used for the metal body 20. Needless to say, when iron is used, a well-known rustproofing treatment is performed.

An anode substrate 33, to which a filament 31 and a grid 32 are attached, is placed on the metal body 20 and adhered by a polyimide resin 34. The filament 31 is a tungsten core wire having a wire diameter of about several tens of μm, which is coated with a mixture of an alkaline earth metal carbonate and an organic binder, and is separated above the anode substrate 33 by a filament holding metal fitting (not shown). Are arranged. The grid 32 is a mesh-shaped thin metal plate, and is arranged between the filament 31 and the anode substrate 33 by a grid supporting frame (not shown).

The anode substrate 33 includes a glass substrate 35, a wiring layer 36 formed on the glass substrate 35, and a wiring layer 3
6, an anode 38 connected to the wiring layer 36 via a through hole formed in the insulating layer 37 in a predetermined display pattern on the insulating layer 37, and a fluorescent substance attached to the anode 38. It is composed of a body 39. A part of the wiring layer 36 is exposed to the outside of the insulating layer 37 to form a plurality of wiring pads, and these wiring pads are connected to the lead pins 21 by the metal wires 23, the filament holding metal fittings, and the grid. One of the support frames is connected. As a result, each lead pin 21 is connected to the filament 3
1, the grid 32 and the anode 38 are connected.

The heating mechanism 3 is composed of a heater arranged so as to surround the metal face 10 and the metal body 20 held by the aligning mechanism 2, and heats the metal face 10, the metal body 20 and the anode substrate 33 by radiant heat. Have a function. The energizing mechanism 4 is configured to connect an AC power source 8 having a predetermined voltage to the lead pins 21 connected to both ends of the filament 31 via the energizing switch 7, and by closing the energizing switch 7, the filament 31 is supplied with a predetermined voltage. Is applied to heat the filament 31 to about 1000 ° C.

The electron beam welding mechanism 5 includes a metal face 1
0 has an electron gun for emitting an electron beam for welding the metal body 20 and has a function of moving the irradiated electron beam at a predetermined speed along a predetermined path. The electron gun of this embodiment can obtain a beam current of 10 to 20 mA at an acceleration voltage of 60 KV. According to this electron gun, when the metal face 10 or the metal body 20 is made of a 426 alloy having a thickness of 0.3 to 1.0 mm, a processing speed of 5 to 6 m / min can be obtained.

Next, the manufacturing process of the fluorescent display tube according to this embodiment will be described with reference to FIG. In the manufacturing process of the fluorescent display tube in this embodiment, an anode substrate, a filament arranged apart from the anode substrate, and a grid provided between the anode substrate and the filament are attached in a vacuum chamber. An exhaust step of evacuating the inside of the vacuum chamber to a vacuum after disposing the metal body and the metal face, and a filament activation step of energizing the filament with a predetermined voltage for a predetermined time after the exhaust step, After the activation step, a sealing step of combining the metal face and the metal body and welding the mating surfaces of them is included.

First, the exhaust process will be described. Figure 2
As shown in (a), the metal face 10 and the metal body 2
Vacuum chamber 1 with 0 attached to mechanism 2
Exhaust until the inside pressure reaches the specified pressure. In this case, the metal body 20 to which the anode substrate 33, the filament 31 arranged apart from the anode substrate 33, and the grid 32 provided between the anode substrate 33 and the filament 31 are attached is combined with the metal body 20. It is attached to the metal body attachment portion 2b. At this time, the energizing mechanism 4 is connected to the lead pin 21 connected to the filament 31.

Further, the metal face 10 is fitted to the mechanism 2
It is attached to the metal face attachment portion 2a. In such a state, the vacuum chamber 1 is sealed, and the vacuum chamber 1 is evacuated by the vacuum evacuation means until the pressure in the vacuum chamber 1 becomes 10 ⁻³ to 10 ⁻⁵ Pa. During the exhaust, the metal face 1 is heated by the heating mechanism 3.
0, the metal body 20 and the anode substrate 33 are heated by radiant heat 3a to degas. In this step, when the pressure in the vacuum chamber 1 becomes equal to or lower than a predetermined pressure, heating is stopped and the process proceeds to the next filament activation step.

In the filament activation process, as shown in FIG.
As shown in FIG. 5, the lead pin 21 connected to the filament 31 is energized by the energizing mechanism 4 in the exhausted state to activate the electron emitting material covering the filament 31. In this case, a predetermined AC voltage is applied to the lead pin 21 connected to the filament 31 to heat the filament 31 to about 1000 ° C., and the alkaline earth metal carbonate covering the filament 31 is thermally decomposed into an oxide. At the same time, the organic binder contained in the coating is decomposed and vaporized.

Here, as the alkaline earth metal carbonate, for example, (Ba, Sr, Ca) CO ₃ is used. (Ba, S
r, Ca) CO ₃ produces (Ba, Sr, Ca) O serving as a thermionic emission source by thermal decomposition. A gas mainly composed of CO ₂ generated by thermal decomposition of an alkaline earth metal carbonate or an organic binder is exhausted by a vacuum exhaust means. In this step, after the filament 31 is energized for a predetermined time, when the inside of the vacuum chamber 1 becomes a predetermined pressure or less, the process proceeds to the next sealing step.

In the sealing step, as shown in FIG.
After the metal face 10 is moved by the aligning mechanism 2 to bring the mating faces of the metal face 10 and the metal body 20 into contact with each other, the electron beam welding mechanism 5 irradiates and welds the electron beam 5a. In this case, the pressure in the vacuum chamber 1 is 10 ⁻³ to 10 ⁻⁵ Pa, the electron beam acceleration voltage is 60 KV, the beam current is 10 to 20 mA, and the thickness of the metal face 10 and the metal body 20 is 0.3 to respectively.
It was 1.0 mm. When the metal face 10 made of 426 alloy and the metal body 20 made of iron were welded under these conditions, a welding speed of 5 to 6 m / min was obtained.

By carrying out the steps described above, FIG.
As shown in (a), the metal face 10 and the metal body 2
The sealing portion 25 is formed by welding on the mating surface of 0, and the envelope of the metal case whose inside is held in vacuum is completed.
Comparing the processing time of these processes with the processing time of the conventional manufacturing process, the lead time of the sealing / evacuation process was shortened to about 1/10 of the conventional time. Therefore, according to this embodiment, the effect of significantly improving the productivity of the fluorescent display tube can be obtained.

In this embodiment, the envelope is composed of the cap-shaped metal face 10 and the plate-shaped metal body 20, but the shape of the metal face 10 and the metal body 20 is not limited to this. For example, as shown in FIG. 3 (b), both the metal face 10 and the metal body 20 may be cap-shaped, or as shown in FIG. 3 (c), the metal face 10 is plate-shaped and the metal body is made of metal. 20 may be cap-shaped. When the metal face 10 has a plate shape, the metal face 2 is attached to the metal face mounting portion 2a of FIG.
0 is attached, and the metal face 1 is attached to the metal body attaching portion 2b.
0 should be attached.

In this embodiment, the electron beam is used for welding the mating surfaces of the metal face 10 and the metal body 20. However, the present invention is not limited to this.
Any welding means capable of welding in vacuum may be used. As a welding means capable of performing welding in a vacuum, for example, laser light such as a carbon dioxide gas laser may be used for welding. In this case, a laser welding mechanism may be provided instead of the electron beam welding mechanism 5 of FIG.

Conventionally, since the low melting point glass has been used to seal the envelope, it is necessary to heat the components of the envelope to a temperature at which the low melting point glass melts, and the sealing step takes time. It was hanging. Further, since the envelope is evacuated through the exhaust pipe having a small exhaust conductance attached to the envelope, it takes a long time to evacuate the gas, and the gas discharge in the envelope is not always sufficient. According to this embodiment, since the envelope is sealed in the vacuum chamber, the envelope is sealed and the chamber is evacuated at the same time, which simplifies the manufacturing process. The manufacturing time is also shortened.

Further, the electron beam welding enables high-speed welding, and the processing time of the sealing process can be shortened to the unit of seconds. Further, since the metal face 10, the metal body 20, and the anode substrate 33 are heated in the vacuum chamber to perform degassing, the exhaust time can be shortened and sufficient degassing can be performed. Further, since the anode substrate 33 is not subjected to atmospheric pressure, a thin glass substrate 35 having a constant plate thickness can be used, so that the anode substrate 33 can be easily manufactured.

Further, since the anode substrate 33 is adhered to the metal body 20, a heat dissipation effect can be obtained through the metal body 20, so that the temperature rise of the anode substrate due to electron impact is suppressed and the luminous efficiency of the phosphor is improved. The effect of improving is also obtained.
In addition, since there are few mechanically fragile glass portions that cause cracks or breaks and the exhaust pipe does not protrude from the envelope, the effect of increasing the degree of freedom in mounting the fluorescent display tube can be obtained.

[0027]

As described above, according to the method of manufacturing a fluorescent display tube of the present invention, it is possible to simultaneously seal the envelope and evacuate the inside of the envelope. The time required for the exhaust process can be shortened, and the productivity can be greatly improved. Further, since the electron beam welding is used for forming the envelope in the sealing step, the processing time of the sealing step can be set to the unit of seconds, and the effect of further improving the productivity can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a fluorescent display tube manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a manufacturing process of the fluorescent display tube according to the embodiment of the present invention.

FIG. 3 is a perspective view showing an outer shape of the fluorescent display tube according to the embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vacuum chamber, 2 ... Alignment mechanism, 2a ... Metal face attachment part, 2b ... Metal body attachment part, 3 ... Heating mechanism, 3
a ... radiant heat, 4 ... energizing mechanism, 5 ... electron beam welding mechanism,
5a ... Electron beam, 6 ... Exhaust pipe, 7 ... Energizing switch, 8
... AC power supply, 10 ... Metal face, 11 ... Glass plate, 1
2 ... Low melting glass, 20 ... Metal body, 21 ... Lead pin, 22 ... Hermetic seal, 23 ... Metal wire, 2
5 ... Seal part, 31 ... Filament, 32 ... Grid,
33 ... Anode substrate, 34 ... Polyimide resin, 35 ... Glass substrate, 36 ... Wiring layer, 37 ... Insulating layer, 38 ... Anode, 3
9 ... Phosphor.

Claims (2)

[Claims] 1. A method of manufacturing a fluorescent display tube, wherein an anode substrate, a grid, and a filament coated with an electron-emitting material are housed in an envelope formed of a metal face having a display window and a metal body, which comprises a vacuum. The metal body having the anode substrate, the filament arranged apart from the anode substrate, and the grid provided between the anode substrate and the filament mounted in a chamber, and the metal face. And an evacuation step of evacuating the inside of the vacuum chamber to a vacuum, and a filament activation step of energizing the filament at a predetermined voltage for a predetermined time after the evacuation step, and after the filament activation step And a sealing process of combining a metal face and a metal body and welding the mating surfaces of the two. Manufacturing method of indicator tube. 2. The method of manufacturing a fluorescent display tube according to claim 1, wherein the sealing step includes welding with an electron beam.