JPH06251746A - Cold cathode low pressure discharge lamp - Google Patents

Abstract

PURPOSE:To enable thinning, weight reduction, high intensity, and the long service life of a back light unit. CONSTITUTION:A phosphor layer is arranged on an inner wall surface, and a glass tube 4 in which noble gas is sealed and a pair of cold cathodes 5 sealed/ installed respectively in both end parts of the glass tube 4, are provided. A cold cathode body part is composed of a bottomed cylindrical cup 5a whose opposed surface is opened and a sleeve 5c formed by filling mercury alloy 5b fitted/arranged in this bottomed cylindrical cup 5a, and the tip surface of the sleeve 5c is situated on the more inside than an opening end part of the bottomed cylindrical cup 5a, and to sum up further, the opening end part of the bottomed cylindrical cup 5a is contracted diametrically (5d).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin-tube cold cathode low-pressure discharge lamp, and more particularly to a cold cathode low-pressure discharge lamp provided with a discharge cold cathode having an improved life.

[0002]

2. Description of the Related Art For example, a cold cathode fluorescent lamp (cold cathode low pressure discharge lamp) is generally used as a light source for a liquid crystal backlight. For such an application, as shown in FIG.
A cold cathode fluorescent lamp is shown in FIG. 6 (b) and FIGS. 6 (a) and 6 (b), each of which shows a different main structure in cross section. That is, a glass tube 1 provided with a phosphor layer which emits light upon stimulation with ultraviolet rays on the inner wall surface and which seals a rare gas
And a pair of cold cathodes 2 sealed at both ends of the glass tube 1. Here, in FIG.
In the case of the configuration of (b), the cold cathode 2 is, for example, a Ni rod 2a
Mercury alloy powder layer 2b integrally arranged with the rod 2a sandwiched therebetween, Fe-Ni plate 2c parallel welded to Ni rod 2a in a manner of sandwiching this mercury alloy powder layer 2b, and Fe-Ni plate 2c. A structure that functions as a discharge electrode by connecting and holding a Ni rod 2a to a lead-in wire 3 that is a getter powder layer 2d that is pressure-bonded and integrated on the outer surface and that is sealed and led out at the end of the glass tube 1. Is made. On the other hand, in the structure of FIGS. 6 (a) and 6 (b), the cold cathode 2'is, for example, a Ni sleeve 2a ', a mercury alloy powder 2b' filled in the Ni sleeve 2a ', and the mercury alloy powder 2b. 'Concave support 2 for fixing the Ni sleeve 2a' stored / filled
The concave support 2c 'is connected to and held by the lead-in wire 3 sealed and led out from the end of the glass tube 1 to function as a discharge electrode.

A cold cathode fluorescent lamp of this kind is generally manufactured by the following procedure. First, the cleaning of the glass tubes 1, 1'starts and the cleaned glass tubes 1, 1 '
The phosphor is coated on the inner wall of 1 ', and then the glass tube 1 coated with the phosphor is placed in a furnace (550 ° C.) for several minutes to burn and degas the coated phosphor. After that, a recess is made in the glass tubes 1 and 1'so that the exhaust side bead mount is fixed (this is called forming), and before the sealing step, the sealing side mount (electrode Material to be used) is sealed to the glass tubes 1 and 1'at the dumet wire portion. Subsequently, in the evacuation process, the glass tubes 1 and 1'are evacuated to about 10 ^-2 to 10 ^-5 Torr, and after exhausting the gas sufficiently, a rare gas is filled therein. Seal. Then, the mercury dispenser attached to the cold electrodes 2 and 2'is heated at a high frequency to discharge mercury into the tube. Finally, aging is performed for several hours to complete the lamp.

Meanwhile, regarding the cold cathode fluorescent lamp as the light source for the liquid crystal backlight, as a market trend, it is important to make the backlight unit thin, lightweight, high in brightness and long in life. As for the built-in light source (lamp), further thinning, longer life and higher brightness are desired.

[0005]

One of the factors that limit the life of a cold cathode fluorescent lamp is that the amount of enclosed mercury is sputtered by ions during the lamp lighting process and the electrode constituent substances are sputtered, and this sputtered layer and mercury combine. Due to such an action, the amount of mercury that should contribute to the discharge gradually decreases, and finally the discharge is stopped. Then, as demands for product performance such as a backlight unit are increased, a thin tube fluorescent lamp is further desired as a light source to be used. However, when the outer diameter of the glass tube 1 is reduced, the glass tube 1 is inevitably reduced. Since the inner diameter becomes small, there arises a problem that the discharge electrode (cold cathode) cannot be sealed in space unless it is made thinner. In other words, in the case of the structure shown in FIGS. 5 (a) and 5 (b), if the diameter of the glass tube 1 is made smaller and the cold cathode is made smaller in space, the amount of mercury enclosed is also reduced. There is a problem that the life is shortened by the time corresponding to.

On the other hand, the structure shown in FIGS. 6 (a) and 6 (b) is effective in this respect. For example, when the inner diameter of the glass tube 1'constituting the cold cathode fluorescent lamp is a thin tube of 2 mm,
Since about twice the amount of mercury is enclosed in a general cold electrode that can be housed / enclosed in the glass tube 1 ', the problem of life due to the lack of mercury is solved. That is, the lamp life phenomenon depends on the consumption of mercury during the lighting process, and since the lamp life and the enclosed mercury amount are in a substantially proportional relationship, it is essential to enclose the amount of mercury corresponding to the desired lifetime. Regarding the lamp life, in addition to the consumption of the enclosed mercury, the electrode constituent substances sputter on the inner wall surface of the glass tube 1,
There is a phenomenon that light transmission is impaired even if the inner wall surface near the electrodes is blackened. And this phenomenon is caused by the above-mentioned FIG. 5 (a), (b)
6A and 6B, the sputtering of the mercury alloy 2b 'and the getter material 2d is particularly remarkable.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a thin-tube cold cathode low-pressure discharge lamp which enables a backlight unit to be thin, lightweight, have high brightness, and have a long life. .

[0008]

A cold cathode low-pressure discharge lamp according to the present invention is a glass tube provided with a phosphor layer on its inner wall surface and containing a rare gas, and both ends of the glass tube are sealed. In a cold cathode low-pressure discharge lamp comprising a pair of (enclosed) cold cathodes, the cold cathode body has a bottomed cylindrical cup having an opening on the opposite surface, and the cold cathode main body is fitted in the bottomed cylindrical cup. A sleeve filled with a mercury alloy, and the tip surface of the sleeve is located inside the opening end of the bottomed cylindrical cup, and if necessary, the diameter of the opening end of the bottomed cylindrical cup is reduced. It is characterized in that it is configured to.

That is, the cold cathode low-pressure discharge lamp according to the present invention comprises a pair of cold cathodes sealed at both ends, a cylindrical cup with a bottom whose opposite surfaces are open, and a sleeve filled with a mercury alloy. The sleeve is fitted and arranged inside the bottomed cylindrical cup, and if necessary, the sleeve is removed from the bottomed cylindrical cup or the sleeve is moved inside the bottomed cylindrical cup. In order to avoid or eliminate the problem, the outline is that the opening of the bottomed cylindrical cup is partially inward and caulked or a tongue piece is provided to reduce the diameter.

[0010]

As described above, by constructing a pair of enclosed cold cathodes, it is possible to easily extend the life of the cold cathode low-pressure discharge lamp and also to reduce the diameter of the lamp (narrow tube). That is, the sleeve filled with the mercury alloy is fitted and arranged in the bottomed cylindrical cup, the side surface is completely covered by the bottomed cylindrical cup, and only the tip portion is partially exposed. In the lighting process, the phenomenon that the electrode constituent substance is ion-sputtered on the inner wall surface of the lamp is also shielded or reduced. Therefore, it is possible to reduce the waste of mercury due to the ion sputtering phenomenon of the electrode constituent material, and to prolong the life of the lamp. On the other hand, the cold cathode itself,
Since it is easy to secure the filling amount of the mercury alloy and it is relatively easy to reduce the diameter of the sleeve and the cylindrical cup with a bottom, it is possible to easily cope with the reduction of the diameter of the lamp (glass tube).

[0011]

Embodiments of the present invention will be described with reference to FIGS.

Example 1 FIG. 1 is a cross-sectional view showing an example of the essential structure of a cold cathode low-pressure discharge lamp according to the present invention, in which 4 is provided with a phosphor layer which emits light upon stimulation by ultraviolet rays on its inner wall surface. A glass tube having an outer diameter of 3.0 mm and an inner diameter of 2.0 mm which contains a rare gas and 5 is the glass tube 4
Is a pair of cold cathodes enclosed at both ends of the cold cathode. Here, the cold cathode 5 is composed of, for example, a bottomed cylindrical cup 5a made of Ni, and a Ni sleeve 5c filled with a mercury alloy 5b fitted and arranged in the bottomed cylindrical cup 5a. And a Ni sleeve 5c filled with the mercury alloy 5b.
Has an outer diameter of 1 mm and a length of 3 mm, and the amount of filled mercury is about 2 mg.
Further, in this configuration example, the Ni sleeve 5c filled with the mercury alloy 5b is inside, and the tip surface of the fitted and arranged sleeve 5c is located inside the open end of the bottomed cylindrical cup 5a. In addition to the above configuration, the opening end of the bottomed cylindrical cup is partially bent inward (a reduced diameter) 5d, and the sleeve 5c fitted and arranged in the bottomed cylindrical cup 5a by this bending 5d. Is fixed.

The cold cathode 5 having the above structure is connected to the lead-in wires 6 sealed and led out at both ends of the glass tube 4, respectively.
The bottom of the bottomed cylindrical cup 5a is connected and held to function as a discharge electrode.

Embodiment 2 FIG. 2 is a cross-sectional view showing another example of the essential structure of a cold cathode low-pressure discharge lamp according to the present invention. Reference numeral 4'denotes a phosphor layer which emits light upon stimulation with ultraviolet rays on the inner wall surface. A glass tube having an outer diameter of 3.0 mm and an inner diameter of 2.0 mm, which is provided and sealed with a rare gas, includes a pair of cold cathodes 5 ', which are sealed at both ends of the glass tube 4'. Here, the cold cathode 5'is, for example, a Ni-made bottomed cylindrical cup 5a ', and a Ni-made sleeve filled with a mercury alloy 5b' fitted and arranged in the bottomed cylindrical cup 5a '.
5c ', and the Ni sleeve 5c' filled with the mercury alloy 5b 'has an outer diameter of 1 mm and a length of 3 mm.
The amount of filled mercury is about 2 mg. In addition, in this configuration example, a Ni sleeve 5c ′ filled with the mercury alloy 5b ′ is provided inside,
The tip surface of the fitted and arranged sleeve 5c 'is located inside the opening end of the bottomed cylindrical cup 5a', and the opening end of the bottomed cylindrical cup 5a 'is caulked inside. By processing (reduced diameter), a caulking portion 5d 'is formed, and the caulking portion 5d' fixes the sleeve 5c 'fitted and arranged in the bottomed cylindrical cup 5a'. There is.

In the cold cathode 5'having the above construction, the bottoms of the bottomed cylindrical cups 5a 'are connected to and held by the lead-in wires 6'which are sealed and led out at both ends of the glass tube 4'. It functions as a discharge electrode.

Comparative Examples 1 and 2 In the cold cathode low-pressure discharge lamps illustrated in Examples 1 and 2, the structure of the cold cathode is shown in FIG. 5 (Comparative Example 1) or in FIG. Cold cathode low-pressure discharge lamps having basically the same configuration except that Comparative Example 2) were produced, respectively.

Table 1 shows the outline of the structure of each cold cathode low-pressure discharge lamp of Examples 1, 2, and 1 and 2.

Table 1 Sample tube outer diameter Tube inner diameter Enclosed mercury amount Example 1 3.0mm 2.0mm 4.0mg Example 2 3.0mm 2.0mm 4.0mg Comparative Example 1 3.0mm 2.0mm 2.0mg Comparative Example 2 3.0mm 2.0mm 4.0mg 3 and 4 show the results of lighting tests of these cold cathode low-pressure discharge lamps at room temperature under a lamp current of 5 mA. FIG. 3 shows the dimension of the blackening of the tube wall (bulb) in the vicinity of the electrode according to the lighting time (horizontal axis), and FIG. 4 shows the luminous flux maintenance factor (vertical axis) and the time elapsed until non-lighting depending on the lighting time (horizontal axis). Show. In addition, in FIG. 3 and FIG. 4, the curve A represents the case of the first embodiment and the curve B represents
Shows the case of Example 2, curve a shows the case of Comparative Example 1, and curve b shows the case of Comparative Example 2. Here, the blackened dimension is a measured value of how much is blackened from the tip of the electrode, and in the case of the present invention, the blackened dimension is
It is as small as 1.0 to 1.5 mm, and the lamp life is about 1.5 times longer. Table 2 shows the results of the lighting test. Table 2 Sample life (hr) Blackening dimension Overall judgment (after 15000 hr, mm) Example 1 15000 or more 3.5 ◎ Example 2 15000 or more 3.5 ◎ Comparative Example 1 10200 5 × Comparative Example 2 15000 or more 4.5 ○

[0019]

As can be seen from the above description, according to the cold cathode low-pressure discharge lamp of the present invention, the sleeve filled with the mercury alloy is fitted and arranged inside the cylindrical cup, and the peripheral surface is covered by the cylindrical cup. With the covered electrode structure, the sputtering on the inner wall surface of the arc tube is effectively shielded. That is, it is possible to reduce the blackening dimension caused by the lighting operation to be short, and the effective light emitting portion becomes long when viewed from the light emission length of the lamp. Further, in this configuration, since it is possible to select the arc tube (glass tube) to have a relatively small diameter, in consideration of the long life and the lengthening of the effective light emitting part,
It can be said that this will greatly contribute to the compactness of light sources for LCD backlights.

[Brief description of drawings]

1A and 1B show an example of a main configuration of a cold cathode low-pressure discharge lamp according to the present invention, in which FIG. 1A is a vertical sectional view and FIG.

2A and 2B show another example of the configuration of the main part of the cold cathode low-pressure discharge lamp according to the present invention, in which FIG. 2A is a vertical sectional view and FIG. 2B is a horizontal sectional view.

FIG. 3 is a curve diagram showing a comparison between a lighting time and a blackening dimension of a cold cathode low-pressure discharge lamp according to the present invention and a conventional cold cathode low-pressure discharge lamp.

FIG. 4 is a curve diagram showing a comparison between a lighting time and a luminance maintenance rate of a cold cathode low-pressure discharge lamp according to the present invention and a conventional cold cathode low-pressure discharge lamp.

5A and 5B show a main part configuration of a conventional cold cathode low-pressure discharge lamp, in which FIG. 5A is a vertical sectional view and FIG. 5B is a horizontal sectional view.

6A and 6B show another main part configuration of a conventional cold cathode low-pressure discharge lamp, in which FIG. 6A is a vertical sectional view and FIG. 6B is a horizontal sectional view.

[Explanation of symbols]

1,1 ', 4,4' ... Glass tube 2,2 ', 5,5'
... Cold cathode 2a ... Ni rods 2a ', 5c, 5c' ... Ni sleeve
2b, 2b ', 5b, 5b' ... Mercury alloy 2c ... Fe-Ni plate
2c '... concave support 2d ... getter powder 3, 3',
6, 6 '... Introductory wire 5a, 5a' ... Cylindrical cup with bottom
5d… Bending part 5d ′… Crimping part

Claims (2)

[Claims] 1. A cold cathode low-pressure discharge lamp comprising a glass tube having a phosphor layer provided on an inner wall surface thereof and sealing a rare gas, and a pair of cold cathodes respectively sealed at both ends of the glass tube. In the above, the cold cathode main body is composed of a bottomed cylindrical cup having an opening on the opposite surface and a mercury alloy-filled sleeve fitted and arranged in the bottomed cylindrical cup, and the tip surface of the sleeve. The cold cathode low-pressure discharge lamp is characterized in that it is located inside the opening end of the bottomed cylindrical cup. 2. A glass tube having an inner wall surface provided with a phosphor layer that emits light when stimulated by ultraviolet rays and containing a rare gas, and a pair of cold cathodes sealed at both ends of the glass tube. In the cold cathode low-pressure discharge lamp consisting of, the cold cathode main body is composed of a bottomed cylindrical cup having an opening on the opposite surface, and a sleeve filled with a mercury alloy fitted and arranged in the bottomed cylindrical cup, The cold cathode low-pressure discharge lamp is characterized in that the front end surface of the sleeve is positioned inside the bottomed cylindrical cup opening end, and the bottomed cylindrical cup opening end is reduced in diameter. .