JPS6334573B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a glass capsule sealed with rare gas and a certain amount of mercury, which is necessary for accurately enclosing a certain amount of mercury in a discharge lamp, particularly a fluorescent discharge lamp. Relating to a manufacturing method.

Generally, a discharge lamp emits visible light based on the excited light emission of a metal vapor sealed in a glass tube, and in particular, in a fluorescent discharge lamp, a small amount of mercury is sealed as this metal vapor. In this case, it is extremely difficult to accurately encapsulate a small amount of mercury into the glass tube, and various encapsulation methods have been studied. For example, a glass capsule containing the necessary amount of mercury and rare gas sealed in a glass tube is attached near the electrode using an appropriate method, and the exhaust is treated in the usual way. After sealing the exhaust tube, For example, a method is known in which a glass capsule is cut open using high-frequency induction heating, and rare gas and mercury are released into a glass tube. As a method for manufacturing such a glass capsule, for example, a glass capillary with both ends open is used, one end of which is heated and sealed with a gas burner, and then the other end is connected to the tip of a mercury guide nozzle provided in a mercury introducing device. Mercury is introduced into the glass capillary along with the rare gas with a predetermined gap between them, and then the other end of the glass capillary and the tip of the nozzle connected to the rare gas supply source are separated with an appropriate gap between them. There is a method of flowing a rare gas into the glass capillary tube in a butted state, and heating and sealing the other end with a gas burner.

However, in this conventional method, after introducing mercury into the glass capillary, the conditions for injecting a rare gas into the glass capillary to heat the other end and sealing the glass capillary, especially the amount of rare gas, and the use of a gas burner to seal the glass capillary. Conditions such as heating temperature and flame size greatly affect capsule yield. In other words, when replacing air in a glass capillary with a rare gas, the amount of rare gas flowing into the glass capillary is almost proportional to the degree of substitution. If the amount is increased, the air flow of the rare gas has the effect of cooling the opening of the glass capillary to be sealed by heating, resulting in the disadvantage that the opening of the glass capillary is further cooled. For this reason, conventional methods have had the drawback of requiring strict process control to accommodate even slight variations in these conditions.

Furthermore, in this conventional method, when mercury is introduced into the glass tube and the other end is heat-sealed, if a rare gas is not allowed to flow into the glass tube, impurity gases such as air or Since the combustion gas from the gas burner flows into the glass tube and is sealed, the purity of the gas in the completed capsule decreases. Therefore, in order to prevent this impure gas from flowing into the glass tube, it is necessary to increase the amount of rare gas, which disturbs the flame of the gas burner and causes a decrease in the heating temperature of the glass tube. Makes the seal unstable. In order to eliminate this inconvenience, the flame of the gas burner is made larger due to the necessity of increasing the amount of heat supplied. As a result, the combustion gas of the gas burner more easily flows into the glass tube being processed, resulting in a decrease in purity within the capsule. The vicious cycle of doing so will repeat.

The present invention has been made in view of these problems, and it is an object of the present invention to provide a method by which capsules for discharge lamps can be manufactured with a high yield.

Hereinafter, one embodiment of the method of the present invention will be described in detail using the drawings.

As shown in Figure 1, the length is 15 mm, the outer diameter is approximately 2 mm,
A glass capillary tube 1 made of lead glass with a thickness of about 0.7 mm and open at both ends is prepared. And this is the second
It is held in the turret type manufacturing apparatus main body 2 as shown in the figure, and is moved intermittently to perform the following operations at each processing operation position a to h.

That is, at position a, the glass tube 1 is held, and at position b, it is held in place. At position c, as shown in FIG. 3a, one lower open end of the glass capillary 1 is heated to a temperature above the softening point of the glass capillary 1 using a gas burner (not shown) and sealed. position d
Now let's cool one end of it. At position e, Fig. 3b
As shown in , the center line of the mercury introduction nozzle 4 provided in the known mercury introduction device 3 is aligned with the extension of the central axis of the glass capillary 1, and the tip 5 of this mercury introduction nozzle 4 and the other parts of the glass capillary are aligned. Approximately 15 ml of liquid metal is introduced into the glass capillary tube 1 through the mercury introduction nozzle 4 with the end 6 separated by a predetermined gap G1, which will be described later.
7 mg of mercury is introduced. At position f, as shown in FIG. 3c, on the extension line of the central axis of the glass tube 1,
A rare gas introduction nozzle 8 connected to a rare gas supply source (not shown), such as argon gas, for example, is aligned. A solenoid valve 9 is provided between the rare gas introduction nozzle 8 and the rare gas supply source. This solenoid valve 9 is
It is synchronized with the turret type manufacturing apparatus main body 2 which moves intermittently. FIG. 4 shows a timing diagram thereof, with reference to which an example of such synchronization will be described. In the figure, section indicates the movement section of the turret type manufacturing apparatus main body 2, and section B indicates the section where it stops at a fixed position. That is, the solenoid valve 9 is opened until the turret type manufacturing apparatus main body 2 moves by a certain distance and stops at the fixed position (point RO in the figure), and the tip 6 of the glass capillary tube 1 and the tip 10 of the rare gas introduction nozzle 8 are connected. Argon gas at a flow rate of approximately 1/min is applied from the rare gas introduction nozzle 8 to the tip 6 of the glass capillary 1 by a gas burner (not shown) installed at this position f, with a predetermined gap G2 (to be described later) in between. While heating the glass tube 1
It begins to flow inside. With this, the glass capillary 1
The air inside is replaced with argon gas. and,
The tip 6 of the glass tube 1 softens due to the heating of the gas burner, and just before it completes sealing (point I in the figure), the solenoid valve 9 is closed to instantly supply argon gas into the glass tube 1. Stop. In this way, if the supply of argon gas into the glass tube 1 is stopped immediately before the tip 6 of the glass tube 1 completes sealing, the temperature of the portion of the glass tube 1 to be sealed will rapidly increase. Complete sealing will occur.

At position g, the glass tube 1 is cooled, and at position h, it is taken out.

When the yield of capsules produced by the above method was investigated, the incidence of sealing defects in glass tubes was as low as 21 pieces/10,000 pieces.

On the other hand, in order to compare this, we also investigated the yield in the case of manufacturing capsules using the conventional method, in which the flow of argon gas into the glass capillary was carried out continuously without stopping at all. The seal failure rate is 453 pieces/
There were 10,000 pieces.

In addition, various experiments were conducted regarding the timing of instantaneously stopping the supply of rare gas into the glass tube.
It has been found that it is most desirable to stop the supply of rare gas when about 75% of the net time that the turret type manufacturing apparatus main body is stopped in a fixed position has elapsed.

Additionally, the following facts were also confirmed through the experiment. That is, the gap G1 between the tip 6 of the glass capillary 1 and the tip 5 of the mercury introduction nozzle 4 in FIG.
is preferably 0.5 mm or less; if it exceeds this, mercury will be scattered before it reaches the inside of the glass tube 1.
The amount of encapsulated mercury varies, and when it is significant, it becomes impossible to introduce mercury. In addition, the gap G2 between the tip 6 of the glass capillary tube 1 and the tip 9 of the rare gas introduction nozzle 8 in FIG. When the capsule is installed in a glass tube and cut and opened, air and the like are diffused into the glass tube, which impairs the characteristics of the discharge lamp and, in severe cases, makes it impossible to light the lamp. On the other hand, if the gap G2 exceeds 5 mm, the airflow of argon gas will be disturbed, which will not only cause a decrease in the degree of substitution as described above, but will also disturb the flame of the gas burner and reduce the heating temperature of the sealed portion of the glass capillary 1. As a result, sealing becomes impossible.

The capsule obtained by the method of the present invention was placed inside a glass tube as usual, and the mercury in the capsule was introduced into the glass tube to produce a fluorescent discharge lamp, and its characteristics were investigated. , this property was good.

As explained above, in the present invention, after a luminescent substance is introduced into a glass capillary, when an inert gas is introduced into the glass capillary, the inflow is instantly stopped immediately before the opening of the glass capillary completes sealing. As a result, the cooling effect of the inert gas airflow on the heated portion of the glass tube is suppressed, which not only greatly improves the yield, but also reduces the amount of inert gas when sealing the glass tube and the amount of glass tube heated by the gas burner. The degree of freedom allowed for conditions such as heating temperature is expanded, so
This method has advantages such as extremely easy process control.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a glass capillary tube used in the method for manufacturing a discharge lamp capsule of the present invention, FIG. 2 is a plan view schematically showing an example of an apparatus for carrying out the method, and FIGS. 3 a and b , c are sectional views showing the main steps in the same method, and FIG. 4 is a timing diagram illustrating the flow of rare gas into the glass capillary tube and the timing of stopping with respect to the operation of the main body of the turret type manufacturing apparatus. DESCRIPTION OF SYMBOLS 1...Glass capillary tube, 2...Turret type manufacturing device main body, 3...Mercury introduction device, 4...Mercury introduction nozzle, 8...Rare gas introduction nozzle, 9...Solenoid valve.

Claims (1)

[Claims] 1. After introducing liquid metal from the opening into a glass capillary whose one end is sealed and the other end is open,
Injecting an inert gas into the glass capillary while heating the opening, and instantaneously stopping the inert gas from flowing into the glass capillary just before the opening completes sealing; A method for manufacturing a capsule for a discharge lamp, comprising heating and sealing the opening.