JP2000072490A - Tempered glass tube for discharge tube and discharge tube using the same glass tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the strength of a high m.p. glass tube used for a discharge tube by dipping a glass tube in a solution of a cesium compound having a m.p. of equal to or below a temp. giving no effect on the glass tube and heating. SOLUTION: Such as a borosilicate glass tube 1 suitable for sealing or joining a high m.p. metal is charged in a metal or ceramic made vessel 2 durable enough against a long term use at a high tamp. of about >=500 deg.C. The powder or the like of cesium nitrate 3 having 414 deg.C m.p. is charged in the vessel 2 to cover the glass tube 1. Next, the vessel 2 is charged to a high temp. furnace 4. The temp. of the inside of the furnace 4 is increased up to a temp. of about 420-450 deg.C, at which cesium nitrate is completely melted and the glass tube is not affected. The glass tube 1 is heat treated by keeping the melting temp. constant for several hours. Then, the temp. of the high tamp. furnace 4 is lowered, the vessel 2 is taken out from the high temp. furnace 4 and further the glass tube 1 is taken out to complete the tempered glass tube.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge tube frequently used as a light source of an electronic flash device for photographing, and more particularly to a glass tube used for a discharge tube and a discharge tube using the glass tube.

[0002]

2. Description of the Related Art Conventionally, an electronic flash device has been used by being attached to a camera, or has been used as an artificial light source for photographing by being installed inside a camera. In recent years, such electronic flash devices have been increasingly miniaturized with the progress of technology,
Above all, there are remarkable miniaturizations of discharge tubes. In particular, the inside of a camera is required to be as small as possible. Recently, a discharge tube having an outer diameter of 2.3 mm and a total length of about 20 mm and generally having a guide number representing brightness of about 12 has been commercialized. Have been. The electronic flash device installed in the camera is
Needless to say, the need to efficiently incorporate many other components of the camera demands even smaller ones. Naturally, bright and small discharge tubes are also required.

As shown in FIG. 2, the discharge tube 8 is provided with tungsten or kovar at both ends of a high melting point metal welding glass tube suitable for sealing a high melting point metal or welding a high melting point metal. Main electrodes 5 and 6 made of high melting point metal such as
, A required amount of a rare gas such as Xe is sealed inside the glass bulb 7, and a trigger electrode 9 formed of a conductive metal paint or a transparent conductive coating is applied to the outer surface of the glass bulb 7. Be done.

[0005] This discharge tube 8 is a well-known lighting electric circuit diagram shown in FIG. 5, and has a main discharge capacitor 18 of about 300 volts with a DC voltage boosted by a DC-DC converter 17.
And the operation of the trigger circuit 19 causes the discharge tube 8
A high-frequency high voltage is applied to the trigger electrode to excite the discharge tube 8, and the charging energy of the main discharge capacitor 18 is instantaneously discharged to cause the discharge tube 8 to emit light.

[0005]

Since the discharge tube discharges the charging energy of the main discharge capacitor 18 instantaneously through both the main electrodes 5 and 6, the main electrodes 5 and 6 have high melting point tungsten, In many cases, Kovar metal is used, and tungsten and Kovar have different compositions in the glass tube to which these high melting metals are deposited, but for example, borosilicate suitable for sealing these metals is used. Glass is used.

By the way, as is well known, the brightness of the discharge tube is increased by increasing the amount of gas sealed in the glass bulb, increasing the charge energy of the main discharge capacitor, which is the luminous energy of the discharge tube, and increasing the discharge energy to the discharge tube. It is known that the voltage increases as the voltage is applied. Therefore, for example, the outer diameter of the glass bulb is 2.0 mm or less, and the thickness is 0.1 mm.
25 mm, and the discharge interval D between the main electrodes 5 and 6 is 10 mm.
In order to obtain a guide number of about 12 which is frequently used at present, it is necessary to increase the amount of the charged gas or to increase the charging energy of the main discharge capacitor. When the discharge tube emits light by increasing the amount of gas filled or by increasing the discharge energy applied to the discharge tube, the impact received by the glass bulb at the time of discharge, particularly the thermal shock, is considerable, and the light is emitted several times. In this case, the glass bulb may be cracked or sometimes broken, and it is undeniable that there is a limit to the miniaturization of the discharge tube using only the current high melting point metal-deposited glass tube.

Accordingly, the present invention provides a tempered glass tube for a discharge tube in which the strength of a high melting point metal welding glass tube suitable for welding a high melting point metal is increased, and a discharge tube using the same.

[0008]

In order to achieve the above-mentioned object, a tempered glass tube of the present invention is provided in a solution of a cesium compound having a melting point not higher than the temperature at which the high-melting point fused glass tube is not affected. By performing the heat treatment by dipping for a predetermined time, the strength can be increased when used in a discharge tube. The discharge tube using the tempered glass tube can have high strength both in a type in which a main electrode is sealed at both ends of a glass bulb and in a type in which both ends of a glass bulb are sealed with a metal plate.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a method of manufacturing a high melting point metal-deposited glass tube in a solution of a cesium compound having a melting point below the temperature at which the high melting point fused glass tube is not affected. Is a tempered glass tube for a discharge tube obtained by dipping and heating at a predetermined temperature for a predetermined time, and a glass tube having high strength suitable for a discharge tube can be provided.

According to a second aspect of the present invention, the high melting point metal-deposited glass tube to be processed has 70%
This is a borosilicate glass containing about 20% before and after (Chemical Formula 2), and the strength of this glass tube can be increased.

The invention according to claim 3 of the present invention is characterized in that the temperature of the heat treatment in the cesium compound solution is a temperature not lower than the melting temperature of the cesium compound and not higher than the strain point of the high melting point metal-deposited glass tube. The heat treatment in the compound solution can strengthen the high melting point metal-deposited glass tube.

According to a fourth aspect of the present invention, the high melting point metal-deposited glass tube is immersed in a solution of a cesium compound having a melting point below the temperature at which the high melting point fused glass tube is not affected. The discharge tube uses a tempered glass tube for a discharge tube that has been heat-treated at a predetermined temperature for a predetermined time. The discharge tube in which the main electrodes are sealed at both ends of the glass bulb can be strengthened against thermal shock.

According to a fifth aspect of the present invention, the main electrodes sealed at both ends of the glass bulb are rod-shaped metal bodies,
A discharge tube resistant to thermal shock can be provided.

According to a sixth aspect of the present invention, there is provided a discharge tube resistant to thermal shock, wherein a main electrode sealed at both ends of a glass bulb has a sintered metal attached to at least one of a bar-shaped metal. can do.

According to a seventh aspect of the present invention, the high melting point metal-deposited glass tube is immersed in a solution of a cesium compound having a melting point lower than a temperature at which the high melting point metallized glass tube is not affected. A tempered glass tube for a discharge tube that has been subjected to a heat treatment for a time is used as a discharge tube, and a metal plate is sealed at both ends of a glass bulb and electrodes are attached to the metal plate to provide a discharge tube resistant to thermal shock. be able to.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

FIG. 1 is an embodiment showing a process of manufacturing a tempered glass tube according to the present invention. In FIG. 1, (a) shows a process for sealing a high melting point metal such as tungsten and Kovar or joining a high melting point metal. For example, a borosilicate glass tube cut into a length suitable for welding a high melting point metal suitable for welding, such as a borosilicate glass tube, is cut at 500 degrees as shown in (b). Put in a metal or porcelain container 2 that can withstand the above-mentioned high temperature use for a long time.
Cesium nitrate powder having a melting point of 14 ° C. was placed in a glass tube 1
And cover it. In this state, the cesium nitrate powder is not sufficiently filled up to the inside of the glass tube 1.

Then, the container 2 is placed in a high-temperature furnace 4 as shown in FIG. 3 (C), and the temperature of the furnace 4 is set to 420 ° C. to 4 ° C. where the cesium nitrate is completely melted and the glass tube is not affected.
After the temperature is raised to 50 ° C., the melting temperature is kept constant and maintained for a predetermined time to heat-treat the glass tube, the temperature of the furnace 4 is lowered, the container 2 is taken out of the furnace 4 and the glass tube 1 is taken out. A tempered glass tube is completed.

Generally, the high melting point glass of borosilicate for welding tungsten has a strain point of about 500 ° C., and the high melting point glass of borosilicate for welding Kovar has a strain point of about 46 ° C.
The temperature inside the furnace 4 is equal to or higher than the temperature at which the cesium nitrate powder 3 is completely melted and completely filled into the glass tube 1 as shown in FIG. It is a necessary condition to set it below the strain point of the tube. The temperature inside the furnace 4 and the time for heating the glass tube 1 are as follows.
The optimum conditions may be determined according to the specifications of the discharge tube to be manufactured and the required strength. Further, in this embodiment, the container 2
The glass tube to put in was explained by one for convenience of explanation,
Actually, a plurality of 100 or 1,000 pieces are put and heated at a time.

The glass tube reinforced by heat treatment in the cesium nitrate solution in this manner is not described,
It is used for a discharge tube as shown in FIG. 2 manufactured by a known method. In the present embodiment, cesium nitrate is used as the cesium compound. However, other cesium compounds satisfying the above-mentioned heating temperature conditions, for example, cesium hydroxide having a melting point of 272 ° C. may be used.

In the discharge tube shown in FIG. 2, a rod-shaped metal made of only a high melting point metal such as tungsten or Kovar is used for the main electrodes 5 and 6, but as shown in FIG. Needless to say, a main electrode formed by attaching a sintered metal 11 obtained by sintering tungsten powder or a mixed powder thereof with another metal powder such as tantalum or titanium may be used at the tip of the metal 10. .

Further, as a discharge tube using the tempered glass tube of the present invention, in addition to the main electrodes 5 and 6 sealed at both ends of a glass bulb as shown in FIG. 2, tungsten or kovar as shown in FIG. The metal plates 13 and 14 are welded to both ends of the glass bulb 12 and the metal plates are fitted with main electrodes 15 and 16 made of a single metal. Good. As a main electrode of this type, the sintered metal 11 of FIG.
14 may be used as an electrode.

[0023]

In order to examine the effect of the strengthened glass tube obtained by strengthening the above high melting point metal welded glass tube, as shown in Table 1,
The two types of glass tubes to be processed were subjected to a heat treatment in a combination of a heating temperature and a heating time in a cesium nitrate solution to actually produce a tempered glass tube. In the table, samples A to D have a glass tube suitable for tungsten welding, and samples E to H have a glass tube suitable for kovar welding.

[0024]

[Table 1]

Using the tempered glass tubes of Samples A to D and the unprocessed high melting point metal-deposited glass tube I of the same type as that of Sample A, which is not heat-treated in a cesium nitrate solution, Twenty discharge tubes each having the configuration as shown in FIG. 2 were manufactured.

Manufacturing specifications of discharge tube Glass tube: outside diameter = 1.8 mm, wall thickness = 0.25 mm Electrodes 5, 6: tungsten metal Discharge interval: D = 12 mm Filled gas pressure: 140 kPa And sample The discharge tubes using the tempered glass tubes of A to D and the discharge tube using the raw glass tube of Sample I are shown in FIG.
Using the lighting circuit shown in FIG. 7, the main discharge capacitor 18 having a capacity of 120 μF was caused to emit light with energy charged at 330 volts, and the light emission test was performed 3,000 times at light emission intervals of 15 seconds.

On the other hand, using a tempered glass tube of Samples E to H and an unprocessed high melting point metal-deposited glass tube J of the same type as that of Sample E and not heat-treated in a cesium nitrate solution, Discharge tubes having the following specifications and the configuration shown in FIG.
0 were produced.

Manufacturing specifications of discharge tube Glass tube: outer diameter = 2.5 mm, wall thickness = 0.5 mm Electrodes 5, 6: Kovar metal Discharge interval: D = 12 mm Filled gas pressure: 140 kPa With respect to the discharge tubes using the tempered glass tubes of Samples E to H and the discharge tubes using the unprocessed glass tubes of Sample J, the main discharge capacitor 18 having a capacity of 155 μF was set using the lighting circuit shown in FIG. Light emission was performed with energy charged at 310 volts, and the light emission interval was set to 30 seconds, and 400 light emission tests were performed.

Table 1 shows the results of luminescence tests of the discharge tubes using the tempered glass tubes of the present invention and the discharge tubes using the unprocessed high melting point welding glass tubes I and J of the samples A to H in Table 1. The results shown in FIG.

[0030]

[Table 2]

From the above results, the tempered glass tube of the present invention has cracks in both the processed tungsten and Kovar high melting point metal-deposited glass tubes as compared with the unprocessed glass tube without any treatment. However, there is no fatal damage as a discharge tube, and the strength is remarkably improved. When the initial value (the light amount before the start of repetitive light emission) was set to 100, the decrease in the light amount after the light emission test was 5% or less, which was a very good and satisfactory result without any practical problem. .

Regarding the heat treatment time, even if the heat treatment time is long, a remarkably good result is not always obtained, and even if the heat treatment time is relatively short, there is no problem in using the heat treatment. It is clear that there is.
In actual use of the discharge tube, heating should be performed in consideration of the outer diameter and thickness of the glass tube, the gas pressure in the glass bulb, the metal to be welded, the charging energy of the main discharge capacitor during light emission, etc. What is necessary is just to determine processing time, heating temperature, etc.

As described above, the present invention can provide a glass tube that is resistant to impact during light emission as a high melting point metal-deposited glass tube used for a discharge tube, and a discharge tube using this glass tube. As a result, it is possible to provide a stable discharge tube that is resistant to thermal shock, thereby enabling the realization of a smaller discharge tube.

[Brief description of the drawings]

FIGS. 1A to 1C are sectional views showing a process of manufacturing a tempered glass for a discharge tube according to the present invention.

FIG. 2 is a sectional view of a discharge tube.

FIG. 3 is a sectional view showing another embodiment of the main electrode of the discharge tube.

FIG. 4 is a sectional view of another discharge tube.

FIG. 5 is a lighting electric circuit diagram of a discharge tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass tube 2 Container 3 Cesium nitrate 4 High temperature furnace 5, 6 Main electrode 7 Glass bulb 8 Discharge tube 9 Trigger electrode 10 Metal body 11 Sintered metal 12 Glass bulb 13, 14 Metal plate 15, 16 Main electrode

Claims (7)

[Claims] 1. A glass tube for a discharge tube using a high-melting-point metal-deposited glass tube suitable for welding a high-melting-point metal, wherein the melting point is not higher than a temperature that does not affect the high-melting-point welded glass tube. A tempered glass tube for a discharge tube, which is immersed in a solution of a cesium compound and heat-treated at a predetermined temperature for a predetermined time. 2. The high melting point metal-deposited glass tube has the following composition in its composition: Is around 70%, Is a borosilicate glass containing about 20% by weight.
A tempered glass tube for a discharge tube according to item 1. 3. The tempered glass tube for a discharge tube according to claim 1, wherein the predetermined heating temperature in the heat treatment is a temperature equal to or higher than a melting temperature of the cesium compound and equal to or lower than a strain point of the high melting point metal-deposited glass tube. 4. A discharge tube using a tempered glass tube for a discharge tube, wherein the tempered glass tube comprises a high melting point metal welding glass tube suitable for welding a high melting point metal to the high melting point welding glass tube. A main electrode sealed at both ends of the tempered glass tube, which is immersed in a solution of a cesium compound having a melting point equal to or lower than a temperature that does not affect and heated at a predetermined temperature for a predetermined time, A discharge tube comprising a rare gas sealed in a glass bulb in which a main electrode is sealed, and a trigger electrode provided on an outer surface of the glass bulb. 5. The discharge tube according to claim 4, wherein the main electrodes sealed at both ends of the glass bulb are rod-shaped metals. 6. The discharge tube according to claim 4, wherein the main electrodes sealed at both ends of the glass bulb are formed by attaching a rod-shaped metal and a sintered metal of a high melting point metal powder to at least one of the rod-shaped metals. . 7. A discharge tube using a tempered glass tube for a discharge tube, wherein the tempered glass tube comprises a high melting point metal welding glass tube suitable for welding a high melting point metal, and a high melting point welding glass tube. A metal plate that is immersed in a solution of a cesium compound having a melting point equal to or lower than a temperature that does not affect and is heat-treated at a predetermined temperature for a predetermined time, and is welded to both ends of the tempered glass tube; A rare gas sealed in a glass bulb sealed with a plate, a main electrode attached to the metal plate so as to face the inside of the glass bulb, and a trigger electrode applied to the outer surface of the glass bulb. Discharge tube consisting of: