JPH04274139A - Fluorescent lamp gas-discharging method - Google Patents

Abstract

PURPOSE:To prevent a drop of a degree of vacuum of a bulb and achieve a stable electric discharging characteristic by energizingly heat a hot cathode, and gas-discharging the inside of the bulb from the vicinity of the hot cathode while discharging gas in a gas-discharge process. CONSTITUTION:A gas-discharge tube 27 is projected from one end of a hot cathode 24 of a bulb 22 in such a manner that a part thereof is projected outward. In a gas-discharge process of a fluorescent lamp, a predetermined current is supplied to the hot cathode 24, followed by heating. While impure gas such as carbon dioxide gas is injected into the bulb 22, the inside of the bulb 22 is evacuated through the gas-discharge tube 27 via a head 28. Consequently, the impure gas can be immediately discharged without passing through the inside of the bulb 22. As a result, it is possible to prevent contamination inside the bulb due to the impure gas and absorption of the impure gas into a fluorescent screen 26 or the like, thereby achieving a stable electric discharging characteristic. Furthermore, a lifetime can be prolonged.

Description

[Detailed description of the invention]

[Object of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for exhausting a fluorescent lamp in which a cold cathode and a hot cathode are used as a pair of electrodes and are housed in a bulb.

0003

2. Description of the Related Art Conventionally, this type of fluorescent lamp has a straight tube type fluorescent lamp 1 shown in FIG. There is one in which the bulb 2 has a built-in electrode as an electrode, and a phosphor film is completely coated on almost the entire inner peripheral surface of the bulb 2. Further, the U-shaped fluorescent lamp 5 shown in FIG. 5 also includes, for example, a U-shaped bulb 6 made of glass.
A cold cathode 7 and a hot cathode 8 are built in as a pair of electrodes, and a phosphor film is entirely coated on almost the entire inner peripheral surface of the bulb 6.

These cold cathodes 3 and 7 are made of, for example, a flat plate or a V-shaped plate made of nickel, while the hot cathodes 4 and 8 are
For example, an alkaline earth metal oxide is coated on the outer surface of a tungsten electrode coil as an electron emitting material (emitter).

However, since this alkaline earth metal oxide is chemically unstable, chemically stable alkaline earth metal carbonates such as (Ba,
In the form of Ca,Sr)CO3, it is first applied to an electrode coil, and then the electrode coil is heated by electricity to release carbon dioxide gas and decompose it into alkaline earth metal oxides.

[0006]The fluorescent lamp 1 configured up to this point
, 5 during the exhaust process during production, these exhaust pipes 9, 1
0 to the heads 11 and 12 of the exhaust machine, and the hot cathode 4
During the energization thermal decomposition, the insides of the valves 2 and 6 are evacuated, and after the evacuation, an appropriate amount of mercury and a rare gas such as argon gas is sealed, and the outer ends of the exhaust pipes 9 and 10 are tipped off.

[0007]

However, in this method of exhausting the fluorescent lamps 1 and 5, exhaust is performed from the side of the cold cathodes 3 and 7, which is opposite to the hot cathodes 4 and 8. Impure gases such as carbon dioxide released from the hot cathodes 4 and 8 due to the thermal decomposition of the hot cathodes 4 and 8 are distributed over almost the entire length of the valves 2 and 6 from the hot cathodes 4 and 8 to the exhaust pipes 9 and 10 on the side of the cold cathodes 3 and 7. and is exhausted from the heads 11 and 12.

For this reason, this impure gas flows through the valves 2 and 6.
When the light passes through almost the entire length of the bulb, it is adsorbed by the phosphor film over almost the entire length, contaminating the inside of the bulbs 2 and 6.

As a result, after assembling the fluorescent lamps 1 and 5,
The impurity gas adsorbed on the phosphor film is released into the bulbs 2 and 6, lowering the degree of vacuum and deteriorating the discharge characteristics. The problem is that the condition varies.

The present invention has been made in consideration of the above circumstances, and its purpose is to immediately exhaust the impure gas released into the bulb by the thermal decomposition of the hot cathode to the outside of the bulb, thereby reducing the degree of vacuum in the bulb. An object of the present invention is to provide a method for exhausting a fluorescent lamp, which can prevent a decrease in discharge characteristics and a decrease in discharge characteristics. [Structure of the invention]

[0011]

[Means for Solving the Problems] In order to solve the above problems, the present invention is constructed as follows.

That is, the present invention is a method for exhausting a fluorescent lamp in which a cold cathode and a hot cathode are used as a pair of electrodes and are housed in a bulb, characterized in that the interior of the bulb is exhausted from the vicinity of the hot cathode.

[0013]

[Operation] When exhausting the inside of the bulb, the hot cathode is heated with electricity, the alkaline earth metal carbonate coated on this hot cathode is decomposed into the same oxide, and impurity gas such as carbon dioxide is removed from the hot cathode through the valve. release it inside.

This impure gas is exhausted from the vicinity of the hot cathode to the outside of the bulb together with the air inside the bulb.

Therefore, according to the present invention, since the inside of the bulb is exhausted from the vicinity of the hot cathode that releases impure gas, impure gas released from the hot cathode hardly passes through the inside of the bulb.
It can be immediately exhausted to the outside of the valve, and it is possible to prevent impure gas from passing through the valve and contaminating the inside thereof.

As a result, quality can be balanced by preventing a decrease in the degree of vacuum within the bulb and the accompanying deterioration of discharge characteristics or variations in local discharge.

[0017]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings.

FIG. 1 is a front view of a main part of one step in an embodiment of the present invention. In the figure, a fluorescent lamp 21 has a cold cathode 23 and a cold cathode 23 at both axial ends of a straight glass bulb 22. The bulb 2 is airtightly sealed by a pair of left and right glass stems 25a and 25b each having a hot cathode 24 implanted therein.
A phosphor film 26 is entirely coated on almost the entire inner circumferential surface of 2.

An exhaust pipe 27 is provided at one end of the valve 22 on the hot cathode 24 side so that a portion of the exhaust pipe 27 projects outward, and the inside and outside of the valve 22 are communicated through the exhaust pipe 27.

The cold cathode 23 is made of, for example, a flat plate or a V-shaped plate made of nickel, while the hot cathode 24 is made of, for example, a tungsten electrode coil containing an alkaline earth metal oxide as an electron emitting material (emitter). It is being applied.

However, since this alkaline earth metal oxide is chemically unstable, chemically stable alkaline earth metal carbonates such as (Ba, C) are used when producing the fluorescent lamp 21.
a, Sr) in the form of CO3, is first applied to the outer surface of the electrode coil, and then in the evacuation process, the electrode coil is heated by electricity to release carbon dioxide gas and decompose into alkaline earth metal oxides. It looks like this.

[0022]The fluorescent lamp 2 configured up to this point
During the first exhaust process, the outer end of the exhaust pipe 27 is connected to the head 28 of an exhaust machine, and the inside of the valve 22 is evacuated to a vacuum.

That is, in this evacuation step, the hot cathode 24 is heated by passing a predetermined current through it to thermally decompose the alkaline earth metal carbonate, and while impurity gas such as carbon dioxide is released into the valve 22, the head 28 is heated. The inside of the valve 22 is evacuated through the vacuum pump. After this evacuation, appropriate amounts of mercury and rare gas are supplied into the valve 22 to pinch off the outer end of the exhaust pipe 27.

Therefore, in this embodiment, when the hot cathode 24 is thermally decomposed, impurity gas such as carbon dioxide is released into the valve 22.
However, since this impure gas is immediately exhausted to the outside of the valve 22 from the exhaust pipe 27 near the hot cathode 24, the impure gas is exhausted without passing through the inside of the valve 22.

For this reason, according to this embodiment, the hot cathode 2
It is possible to prevent the impurity gas emitted from the bulb 22 from passing through the bulb 22, contaminating the inside thereof, and being absorbed by the phosphor film 26 and the like.

Therefore, it is possible to prevent the degree of vacuum of the bulb 22 from decreasing, and also to prevent and stabilize local discharge during evacuation and variations in the discharge characteristics of the fluorescent lamp 21 after assembly is completed.

As a result, according to this embodiment, A in FIG.
As shown by the line, if the brightness at the beginning of the lamp life is 100% and the lamp life is considered to have ended when the brightness drops to 60% or less, then the fluorescence when exhausted from the cold cathode 23 side The lamp life can be extended, for example, by about 1.5 times compared to the B line which indicates the lamp life.

In the above embodiment, the straight tube fluorescent lamp 2
1 has been described, the present invention is not limited thereto, and can be applied to, for example, a U-shaped fluorescent lamp 31 shown in FIG. 3, and the bulb 32 may be U-shaped.
Alternatively, other shapes may be used, and in FIG. 2, parts common to those in FIG.

[0029]

As explained above, the present invention evacuates the inside of the bulb from the vicinity of the hot cathode, so that impure gas released into the bulb during thermal decomposition of the hot cathode hardly passes through the inside of the bulb. , can be immediately drained out of the valve.

Accordingly, it is possible to prevent impure gas emitted from the hot cathode from passing through the bulb and being adsorbed by the phosphor film and the like, lowering the degree of vacuum and causing deterioration or variation in discharge characteristics.

[Brief explanation of the drawing]

FIG. 1 is a front view of main parts showing one step in an embodiment of the present invention.

FIG. 2 is a front view of main parts showing one step in another embodiment of the present invention.

FIG. 3 is a graph showing the extension of lamp life according to the embodiment shown in FIG. 1;

FIG. 4 is a front view of main parts showing an evacuation process of a conventional straight tube fluorescent lamp.

FIG. 5 is a front view of main parts showing the exhaust process of another conventional example.

[Explanation of symbols]

21 Fluorescent lamp 22 Valve 23 Cold cathode 24 Hot cathode 26 Phosphor film 27 Exhaust pipe 28 Head

Claims (1)

[Claims] 1. A method for exhausting a fluorescent lamp in which a cold cathode and a hot cathode are incorporated in a bulb as a pair of electrodes, the method comprising exhausting the interior of the bulb from the vicinity of the hot cathode. .