JPH0548571B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fluorescent display tube in which an exhaust pipe for evacuating the inside of a vacuum container has been removed, and in particular, the present invention relates to a fluorescent display tube in which an exhaust pipe for evacuating the inside of a vacuum container has been removed. The present invention relates to a method of manufacturing a sealed fluorescent display tube.

[Prior Art] Various techniques have been proposed in the past for removing the exhaust pipe from a fluorescent display tube. As the first method,
Fluorescent display tubes usually have a front glass, side frame, and anode substrate each hermetically sealed with frit glass to form a vacuum container, but there is a method in which any one of the sealing surfaces is sealed in a vacuum. (For example, Tokukai Sho
53-15749), or as a second method, provide an exhaust hole in any of the above three parts constituting the vacuum container, and seal each sealing surface with fritted glass in an atmosphere other than vacuum (for example, N ₂ atmosphere). A method has been proposed in which the frit-sealed product is held in a vacuum and the exhaust hole is sealed.

The first method has not been put to practical use due to the lack of suitable sealing materials, poor workability, and reliability problems regarding vacuum leaks.

On the other hand, the second method includes, for example,
130274 (referred to as A method) and JP-A-59-189534 (B method).
The following methods have been proposed: Japanese Utility Model Publication No. 58-10291 (referred to as method C), and Utility Model Application Publication No. 60-149056 (referred to as method D).

[Problem that the invention seeks to solve]

However, in method A, in order to form a metal layer around the exhaust hole of the substrate, it is necessary to use ceramic as the substrate and perform metallization, or in the case of a glass substrate, to form a _Ni layer by vacuum evaporation, etc. The former increases the material cost, and the latter requires an additional step in the vacuum deposition process. In addition, when directly sealing the exhaust mechanism with a sealing member, the exhaust hole cannot be made as large as the sealing material is held in the exhaust hole only by the surface tension of the sealing material when it melts. , the exhaust conductance is not improved much. One way to improve this exhaust conductance is to seal the exhaust hole with a plug, but in both cases sealing material is placed on the exhaust hole in advance, so the exhaust baking temperature is lower than the sealing temperature of the exhaust hole. The temperature must be lower than the stop temperature, and the gas released from the inside of the fluorescent display tube at that temperature difference remains sealed inside the tube without being exhausted, which is far worse than the vacuum level achieved by the exhaust system. It will be sealed in a vacuum.

In method B, since a metal layer is not formed in the exhaust hole portion of the substrate, it is considered that it is impossible to bond the exhaust plug to the substrate or that the reliability of vacuum leakage cannot be ensured. In other words, no other technology has been reported for bonding metals and insulators using ultrasonic pressure bonding. In addition, fluorescent display tubes have a phosphor layer formed on the anode and a thin tungsten wire as the cathode, and applying ultrasonic vibrations to these can cause the phosphor to fall off and the filament wire to break. There is.

In Method C, a small ceramic substrate with a metal layer and an exhaust hole is attached to the inside of the fluorescent display tube, so the ceramic substrate is expensive and the workability of the installation process is poor since it is attached inside the tube.
This method has drawbacks such as the large restrictions on the mounting position in order not to interfere with the luminescent display pattern of the fluorescent display tube, and other drawbacks common to method A.

In method D, oxide solder, that is, fritted glass is used as the sealing material. However, when fritted glass is melted in a vacuum,
For reasons considered below, foaming of the fritted glass cannot be avoided, and reliability of adhesive strength and vacuum leakage cannot be ensured.

(i) Since frit glass is a powder, it adsorbs a large amount of gas and moisture during its manufacturing process and storage, which is released when melted in vacuum, causing the frit to explode.

(ii) The fritted glass is made into a paste using an organic binder and applied to the adhesive part, but the undecomposed organic binder is contained in the fritted material, which is released as CO ₂ and causes the fritted material to foam.

(iii) Since frit glass melts at a low melting point, it contains a large amount of _PbO , and other oxides are added to adjust the melting temperature and coefficient of thermal expansion. The O in these oxides is decomposed and released, causing the frit to foam.

Note that foaming of the fritted glass does not occur only in a vacuum, but also occurs when sealed under atmospheric pressure, but in this case, the bubbles are very small and do not cause any particular trouble.

On the other hand, the baking heat curve during exhaust of a fluorescent display tube with an exhaust pipe is as shown in FIG. 7, and the baking temperature is usually 300 to 350°C.
In this case, the exhaust pipe is sealed and cut without exposing the fluorescent display tube to a temperature higher than the baking temperature, so that all gas released into the tube at a temperature up to the baking temperature is exhausted.

However, when fritted glass was used as an adhesive,
The baking heat curve during exhaust of the fluorescent display tube without exhaust tube is as shown in FIG. In this case, the sealing temperature, that is, the melting temperature of the frit, is approximately 450°C, and the gas released into the tube during the rise from the exhaust baking temperature to the sealing temperature is not exhausted to the outside of the tube and the exhaust hole is blocked. As a result, the degree of vacuum inside the tube remains low.

In addition, unless only the exhaust hole is locally heated to the frit melting temperature, the entire fluorescent display tube will reach the frit melting temperature and the previously sealed frit glass will melt again. In order to avoid this, there was a problem in that the heating device had to be complicated.

The present invention has been made in order to solve the various problems of the prior art described above, and its purpose is to airtighten the sealed part when airtightly sealing an exhaust hole provided in a part of a vacuum container. An object of the present invention is to provide a method for manufacturing a fluorescent display tube with improved performance and reliability.

[Means for solving problems]

That is, the present invention includes a vacuum container configured by frit-sealing an anode substrate, a side frame, and a flat glass, and a fluorescent lamp that hermetically seals an exhaust hole provided in a part of the vacuum container in a vacuum. In the method for manufacturing a display tube, an exhaust hole pedestal having a hole corresponding to the exhaust hole of the vacuum container and having a plurality of supporting parts formed on the circumferential surface of the exhaust hole pedestal is attached to the outer surface of the exhaust hole of the vacuum container using frit glass. A process of airtight fitting,
a step of holding an exhaust hole plug formed to close the hole of the exhaust hole pedestal and having a support portion facing each of the support portions facing the exhaust hole pedestal by coupling each of the support portions; A step of placing the vacuum container in a vacuum atmosphere, pressing the exhaust hole plug against the exhaust hole pedestal while heating and evacuating, and airtightly joining the exhaust hole plug and the exhaust hole pedestal with a low melting point metal interposed therebetween. It is characterized by comprising the following.

[Effect]

Therefore, in the present invention, by using a low melting point metal as the airtight joint material of the exhaust hole plug, it is possible to achieve a highly reliable airtight joint without causing foaming unlike when fritted glass is used. Further, the positioning of the exhaust hole pedestal and the exhaust hole plug in a vacuum atmosphere can be easily performed using the support portions provided on both.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a schematic diagram showing an example of a fluorescent display tube manufactured by the method of the present invention, FIG. 2 is a cross section taken along the line - in FIG. 1, and FIG. 3 is a diagram showing an exhaust hole portion according to the present invention. An example of the process of hermetically sealing in vacuum will be shown. Here, an anode wiring pattern (not shown) is formed on the anode substrate 2, and leads for each electrode are taken out, and a phosphor anode 6,
A control electrode 7, a filament cathode 8, etc. are attached. The windshield 1 and the side frame 3 are hermetically sealed in advance by a frit glass _4-1 to form a cover glass, and a frit glass 4 is attached to the end of the side frame 3 which becomes the sealing surface with the anode substrate 2.
- ₂ is applied and pre-baked in an oxidizing atmosphere to remove the binder.

Next, the anode substrate 2 and the cover glass are placed in a fritted glass 4-4 in a non-oxidizing atmosphere such as _N2 and at atmospheric pressure.
₂ to form a vacuum container. In addition,
Up to this step, it can be formed in the same steps as a conventional fluorescent display tube having an exhaust pipe. Further, the anode substrate 2 is provided with an exhaust hole 11 of a predetermined size.

Next, on the outer surface of the anode substrate of the exhaust hole 11,
As shown in FIG. 4, the exhaust hole pedestal 13 and the anode substrate 2 are hermetically connected by interposing frit glass 12 coated in paste form on at least one of the outer surface of the anode substrate 2 or one surface of the exhaust hole pedestal 13. do.

At this time, the exhaust hole pedestal 13 is a disc-shaped pedestal main body 1 in which a hole 13a corresponding to the exhaust hole 11 of the anode substrate 2 is formed, as shown in FIGS. 4a and 4b.
3b, two supporting parts 13c and an end part 13 bent on both sides from the outer peripheral surface of the pedestal main body 13b.
d, and its pedestal main body 13b corresponds to the frit bonding part. It is preferable that this air-tight joining of the exhaust hole pedestal 13 and the anode substrate 2 is carried out at the same time as the sealing process of the cover glass and the anode substrate 2.
It is also possible to carry out the process in a separate process without being particularly limited to this. Furthermore, the frit glass 12 does not need to be applied in the form of a paste, and may be press-formed into a sheet. The exhaust hole pedestal 13 is made of 426 alloy (N _i : 42, C _r : 6,
Remaining Fe ₎ or 50-50 alloy (F _e : 50, _Ni : 50), etc. are used.

Next, as shown in FIG. 4, a disk-shaped plug body 14a is formed to be the adhesive surface to the exhaust hole pedestal 13, and a plug body 14a is formed on both sides of the outer periphery of the plug body 14a so as to face each support portion 13c. The exhaust hole plug 14 is made of metal such as 426 alloy and is composed of two supporting parts 14b and an end 14c, and each end 14c and the end 13d of the exhaust hole pedestal 13 are bonded together by spot welding or the like. After fixing, the exhaust hole plug 14 is pulled, and the exhaust hole pedestal 13 and the exhaust hole plug 14 are placed facing each other with a predetermined distance apart. In addition, in Fig. 4, the code 1
Arrows indicated by 9 represent welding points.

Next, the vacuum container, that is, the fluorescent display tube 20 with the exhaust hole stopper 14 fixed at the end to the exhaust hole pedestal 13,
As shown in FIG. 3, by placing it in a vacuum chamber 21 or the like and evacuating the chamber 21, the inside of the fluorescent display tube 20 is evacuated through the exhaust hole 11, and the inside of the fluorescent display tube 20 is evacuated through the exhaust hole 11. The heat source 22 performs predetermined operations such as exhaust baking and activation of the filament of the fluorescent display tube. Thereafter, the exhaust hole plug 14 is pressed against the exhaust hole pedestal 13 using the push-up jig 23, and a low melting point metal (not shown) that has been interposed between the exhaust hole plug 14 and its pedestal 13 is used to connect the two. Make an airtight connection.

At this time, the low melting point metal may be in the form of a sheet and have the same shape as the plug body 14a of the exhaust hole plug 14, or may be fused to the joint surface of the plug body 14a in advance, and the material may be, for example, P. _b (:95)-S _o (:5)
By using a type of solder or the like and setting the exhaust baking temperature to a temperature slightly higher than the melting point (approximately 350°C), low melting point metals can be melted and joined simply by pressing the exhaust hole plug 14. .

In this way, the exhaust hole plug 14 is connected to the exhaust hole pedestal 1.
3, the fluorescent display tube 20 is taken out from the vacuum chamber 21, and the supporting portion 13c of the exhaust hole pedestal 13 and the supporting portion 14b of the exhaust hole plug 14 are cut off from their bases. As shown in FIG. 2, a fluorescent display tube without an exhaust pipe is obtained. In FIGS. 1 and 2, reference numeral 5 indicates each of the pedestals 13 and plugs 1 that hermetically sealed the exhaust hole 11.
4 shows an exhaust hole plug part composed of 4 parts.

Incidentally, by performing half-etching in advance at the cut-off positions of each of the supporting parts 13c and 14b, the cut-off can be easily performed.

FIG. 5 is a schematic view corresponding to FIG. 3 showing another embodiment of the present invention, and FIG. 6 is a detailed view of the exhaust hole pedestal and exhaust hole plug part of FIG. 5. This example is
A fritted glass 12 is placed on the outer surface of the exhaust hole of the anode substrate 2.
A disc-shaped pedestal main body 15b in which a hole 15a corresponding to the exhaust hole 11 is formed as an exhaust hole pedestal made of metal that is airtightly joined with the pedestal main body 1.
Two supporting parts 1 formed on both sides of the outer peripheral surface of 5b
5c and a slit groove 15d formed along the longitudinal direction of each support portion 15c. And this exhaust hole pedestal 15
By closing the hole 15a and providing an exhaust hole plug 16 which is slidably formed by fitting into the slit groove 15d, these are airtightly joined in the same process as in the embodiment described above. It is something. In this case, the exhaust hole plug 16 has a disk-shaped plug body 16a that becomes the adhesive surface to the exhaust hole pedestal 15.
The stopper main body 16a is composed of two supporting parts 16b formed on both sides of the outer circumferential surface so as to be able to fit into each of the slit grooves 15d.

That is, in this embodiment, the exhaust hole pedestal 1 is provided with frit glass 12 on the outer surface of the exhaust hole portion of the anode substrate 2.
The steps up to the step of airtightly joining the exhaust hole base 1 are carried out through the same steps as in the above embodiment, but after this step, the exhaust hole pedestal 1
As shown in FIG.
Each supporting member 16b of the exhaust hole plug 16 is fitted between the holes to hold the exhaust hole plug 16 in a slidable state. Next, as shown in FIG. 5, the assembled vacuum container, that is, the fluorescent display tube 20 is placed in a vacuum chamber 21, etc.
By evacuating the inside of the fluorescent display tube 20, the inside of the fluorescent display tube 20 is evacuated through the exhaust hole 11, while baking is performed using the heat source 22, and predetermined operations such as activation of the filament are performed. After that, press down jig 2
3, the exhaust hole plug 16 is slid and pressed along the slit groove 15d of the exhaust hole base 15, and the low melting point metal (not shown) interposed between the exhaust hole plug 16 and the exhaust hole base 15 is melted. to airtightly connect the two.

At this time, the exhaust hole pedestal 15 and the exhaust hole plug 16 are
A low melting point metal sheet is used or it is welded to one side of the exhaust hole plug 16 in advance, and the low melting point metal is used for joining. Furthermore, if the baking temperature of the fluorescent display tube 20 in a vacuum is about 350°C and the low melting point metal is, for example, an alloy whose main component is P _b (melting point of pure P _b is 327°C), during the baking process, Alternatively, after baking is completed and the temperature is decreasing, connect the exhaust hole plug 16 to the exhaust hole pedestal 15.
By bringing the metal into pressure contact with the fluorescent display tube, the low melting point metal is melted by the heat of the fluorescent display tube, and the bonding is performed.

In this way, the exhaust hole plug 16 is connected to the exhaust hole pedestal 1.
5, the fluorescent display tube 20 is taken out from the vacuum chamber 21, and the supporting parts 15c and 16b of the exhaust hole pedestal 15 and the exhaust hole plug 16 are cut off from their bases, thereby creating a fluorescent display without an exhaust pipe. Can manufacture optical display tubes. In addition, each exhaust hole pedestal 15
By performing half-etching in advance on the cut-off positions of the support portions 15c and 16b of the exhaust hole plug 16, the cut-off can be easily performed.

In the above-mentioned embodiment, the exhaust hole pedestal and the exhaust hole plug are provided with two supporting parts and are held together by spot welding or a sliding mechanism, but the present invention is not limited to this. It is also possible to provide an arbitrary number of supporting parts facing both the exhaust hole pedestal and the exhaust hole, and to hold both by any means.

〔Effect of the invention〕

As explained above, according to the present invention, since a low melting point metal can be used as the airtight joint material of the exhaust hole plug, a highly reliable airtight joint can be achieved without foaming unlike when fritted glass is used. It becomes possible. In addition, positioning of the exhaust hole pedestal and the exhaust hole plug in a vacuum atmosphere such as a vacuum chamber can be done using the support provided on both, which makes it extremely easy, and the structure of the exhaust system can be significantly simplified. This has the effect of improving quality and simplifying equipment when producing a fluorescent display tube without an exhaust pipe.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing an example of a fluorescent display tube manufactured by the manufacturing method of the present invention, FIG. 2 is a cross-sectional view taken along the line II in FIG. 1, and FIG. 3 is an embodiment of the present invention. 4a and b are detailed side views and perspective views of the exhaust hole pedestal and exhaust hole plug in the embodiment of FIG. 3, and FIG. FIG. 6a is a schematic process diagram for hermetically sealing an exhaust hole section in a vacuum according to another embodiment of the present invention.
and b is an exhaust hole pedestal for the embodiment shown in FIG.
Detailed side view and perspective view of the exhaust hole plug part, No. 7
FIG. 8 is an explanatory diagram showing an exhaust baking heat curve of a fluorescent display tube with an exhaust pipe, and FIG. 8 is an explanatory diagram showing an exhaust baking heat curve of a fluorescent display tube without an exhaust pipe. 1... Windshield, 2... Anode substrate, 3...
... Side frame body, _4-1 , _4-2 ... Fritz glass,
5... Exhaust hole plug part, 6... Fluorescent anode, 7... Control electrode, 8... Filament cathode, 11... Exhaust hole, 12... Fritted glass, 13, 15... Exhaust hole pedestal, 14, 16... Exhaust hole plug, 20... Fluorescent display tube, 21... Vacuum chamber, 22... Heat source, 23... Pushing jig.

Claims (1)

[Claims] 1. A method for manufacturing a fluorescent display tube, which includes a vacuum container configured by frit-sealing an anode substrate, a side frame, and a flat glass, and hermetically seals an exhaust hole provided in a part of the vacuum container in a vacuum. a step of airtightly joining an exhaust hole pedestal, which has a hole corresponding to the exhaust hole of the vacuum container and has a plurality of support parts formed on its outer peripheral surface, to the outer surface of the exhaust hole of the vacuum container using frit glass; , a step of holding an exhaust hole plug formed to close the hole of the exhaust hole pedestal and having a support portion facing each of the support portions facing the exhaust hole pedestal by coupling each of the support portions; Next, the vacuum container is placed in a vacuum atmosphere, and the exhaust hole plug is pressed against the exhaust hole pedestal while being heated and evacuated, and the exhaust hole plug and the exhaust hole pedestal are hermetically connected by a low melting point metal interposed therebetween. A method for manufacturing a fluorescent display tube, comprising the steps of: