JPH08321279A - Cold cathode low pressure discharge lamp - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a thin-tube cold-cathode low-pressure discharge lamp that can make the backlight unit thin, lightweight, high-intensity, and have a long life, and that suppresses or reduces the rise in the tube wall temperature. With the goal. A cold cathode comprising a glass tube 5 having a phosphor layer 6 provided on its inner wall surface and sealing a rare gas, and a pair of cold cathodes 7, 7'sealed at both ends of the glass tube 5, respectively. In the low-pressure discharge lamp, the cold cathode 7, 7'main body has a metal cylindrical cup 7a having an outer peripheral surface with an opening facing the insulating layer 7c, and a filling tip inside the cylindrical cup 7a. A cold cathode low-pressure discharge lamp characterized in that it has a mercury alloy 7b (7b ') whose surface is located inward of the opening end and which is filled with a form of a cavity 8. For example, the structure is such that the emitter 10 is attached to the inner wall surface of the cavity 8.

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 having 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, FIG. There is provided a cold cathode fluorescent lamp as shown in cutaway cross section. That is, a glass tube 2 having an inner wall surface provided with a phosphor layer 1 that emits light upon stimulation with ultraviolet rays and sealing mercury and a rare gas (discharge medium), and a pair of glass tubes 2 sealed at both ends thereof. And cold cathodes 3 and 3 '. In the case of the configuration shown in FIG. 3, the cold cathodes 3 and 3'are, for example, a cylindrical cup 3a made of Ni, and a mercury alloy powder (or a mercury alloy and a getter) filled / disposed in the cylindrical cup 3a. Mixed powder) 3
b. For example, the bottom surface side of the cylindrical cup 3a is connected to and held by the lead-in wire 4 which is formed of, for example, a mercury zircon alloy and which is sealed and led out at the end of the glass tube 2 and functions as a discharge electrode. Consisting of made up. In this specification,
The cylindrical cup 3a refers to, for example, a bottomed cylindrical shape, a cylindrical shape, or sleeves.

A cold cathode fluorescent lamp of this kind is generally manufactured by the following procedure. First, starting from cleaning the glass tube 2, the phosphor is applied to the inner wall of the cleaned glass tube 2, and then the glass tube 2 coated with the phosphor is put in a furnace (550 ° C.) for several minutes to apply the applied fluorescence. Baking the body (formation of the phosphor layer 1) and degassing. After that, a recess 2a is formed in the glass tube 2 so that the exhaust side bead mount is fixed (this is called forming), and a sealing side mount (electrode 3, 3 ′ side) is sealed to the glass tube 2 at the dumet wire portion. Then, in the evacuation process, the inside of the glass tube 2 is 10 ^-2 ...
After exhausting to about 10 ⁻⁵ Torr and exhausting sufficiently, a rare gas is sealed and then the exhaust mount bead portion and the glass tube 2 are sealed. Then, the mercury dispenser attached to the cold electrodes 3 and 3'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. Along with this, the light source (lamp) to be incorporated is also required to be further thinned, have a longer life, and have higher brightness. In response to these demands, various attempts have been made to restructure the discharge electrodes (cold electrodes) 3 and 3 '(for example, Japanese Patent Laid-Open No. 4-109546).

[0005]

The cold cathode fluorescent lamp is
When a predetermined potential is applied between the pair of cold cathodes 3 and 3 ′ through the lead-in wire 4, secondary electrons are emitted from the cold cathodes 3 and 3 ′ by the generated initial plasma ions, and inside the glass tube 2. Discharge starts. Then, ultraviolet rays are radiated by the resonance transition of the mercury atoms excited by the electron energy accompanying this discharge, the ultraviolet rays are absorbed by the phosphor layer 1 on the inner wall surface of the glass tube 2, and the phosphor layer 1 is excited. Generates visible light. However, the cold cathode fluorescent lamp having the above-described configuration is often found to have the following disadvantages in lighting and operation. That is, during discharge, the glow is cold cathode 3,
It spreads to the outer peripheral surface of 3 ', and "flicker" occurs in the glow,
A flicker phenomenon is observed on the electrode part. Further, there is a problem that the temperature of the outer surface of the electrode rises due to the spread of the glow over the entire area of the electrode, and this heat is transmitted to the glass tube 2 to raise the tube wall temperature. Such problems as stability as a light source and the tendency to cause an undesired temperature rise are caused by deterioration of image quality and short life of the cold cathode low pressure discharge lamp itself when used as a backlight of a liquid crystal display device, for example. Means conversion. The flicker phenomenon of the electrode portion and the problem of rise in the temperature of the tube wall are liable to be hindered in the miniaturization of the liquid crystal display device due to, for example, the stability of the device function caused by the heat resistance of other peripheral parts. This is a serious problem in terms of practical use, including the point.

Further, the cold cathode fluorescent lamp has an advantage that the structure is relatively simple, but has a problem that the cathode drop voltage that does not contribute to light emission is high and the luminous efficiency of the lamp is low. For the problem of the cathode drop voltage, it has been attempted to provide an activated emitter layer on the surfaces of the cold cathodes 3 and 3 ', but when it is consumed by sputtering or the like, the cathode drop voltage increases and the lamp drops. There is a problem that the efficiency is reduced and it does not function as a highly efficient light source.

The present invention has been made in view of the above circumstances, and it is possible to make the backlight unit thin, lightweight, have high brightness, have a long life, and to suppress or reduce the rise of the tube wall temperature. An object of the present invention is to provide a cold cathode low pressure discharge lamp.

[0008]

According to a first aspect of the present invention, there is provided a glass tube provided with a phosphor layer on an inner wall surface thereof and sealing a rare gas, and a pair of cold tubes respectively sealed at both ends of the glass tube. In a cold cathode low-pressure discharge lamp including a cathode, the cold cathode main body comprises a metal cylindrical cup having an insulating layer coated on an outer peripheral surface having an opposing surface, and a tip end surface filled in the cylindrical cup. Is provided inside the opening end portion and is filled with a mercury alloy so as to form a hollow portion. A cold cathode low-pressure discharge lamp.

According to a second aspect of the present invention, there is provided a cold cathode 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 low-pressure discharge lamp, the cold cathode main body includes a metal cylindrical cup having an outer peripheral surface having an opening facing the insulating layer, and a filling tip surface inside the cylindrical cup that is located inside the opening end. A cold cathode low-pressure discharge lamp, comprising: a mercury alloy that is located at the position of 1 to fill a cavity to form a cavity; and an emitter layer that is deposited on the inner wall surface of the cavity of the cylindrical cup.

According to a third aspect of the present invention, in the cold cathode low pressure discharge lamp according to the first or second aspect, the insulator layer covering the outer peripheral surface of the metal cylindrical cup is a ceramic layer. is there.

That is, the cold cathode low-pressure discharge lamp according to the present invention is a metal cylinder in which a pair of cold cathodes sealed at both ends are open at the surfaces facing each other and the outer peripheral surface is covered with an insulating layer. In a configuration comprising a cup-shaped cup and a mercury alloy filled in the cylindrical cup, the mercury alloy is filled and arranged on the bottom wall surface side (introduction line connection side) of the cylindrical cup,
The outline is that a cavity is formed on the open end side. The insulator covering the outer peripheral surface of the cylindrical cup may be glass, ceramics, or a mixed system thereof.

[0012]

In the invention of claim 1, since the outer peripheral surface of the metal cylindrical cup forming the cold cathode main body is covered with the insulating layer, the glow spreads only on the inner wall surface of the cylindrical cup and the cavity. Therefore, the "flicker" of the glow in the low current region is eliminated, and as a result, the flickering phenomenon of the electrode portion also disappears.

According to the second aspect of the present invention, the outer peripheral surface of the metallic cylindrical cup forming the cold cathode main body is covered with the insulator layer, and the emitter layer is adhered to the inner wall surface of the hollow portion of the cylindrical cup. Therefore, the scattering of the electrode constituent substances is suppressed, and the thermionic flow having a high electron density is emitted only from the inner wall surface of the hollow portion of the cylindrical cup. It is possible to secure high luminous efficiency.

According to the third aspect of the invention, the insulator layer covering the outer peripheral surface of the cylindrical cup is a ceramic layer,
The reliability of the operation in the invention according to claim 1 or claim 2 is further promoted.

[0015]

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

Embodiment 1 FIG. 1 is a cross-sectional view showing an example of the essential structure of a cold cathode low pressure discharge lamp of this embodiment. In FIG. 1, reference numeral 5 denotes a glass tube having an inner wall surface provided with a phosphor layer 6 that emits light upon stimulation with ultraviolet rays, and a rare gas sealed glass tube having an outer diameter of 3.0 mm and an inner diameter of 2.0 mm. Is a pair of cold cathodes enclosed at both ends of the cold cathode. Here, the cold cathode 7,
7'is, for example, a cylindrical cup (or sleeve) 7a made of Ni with an outer diameter of 1 mm and a length of 3 mm, about 2 mg of mercury alloy 7b filled and arranged in the cylindrical cup 7a, and the cylindrical cup. 7a is composed of an insulator layer 7c (for example, ceramics such as aluminum oxide) having a thickness of about 20 to 50 μm that covers the outer peripheral surface of the cylindrical cup 7a. It is shaped to leave. That is, the inside of the cylindrical cup 7a is divided into a mercury alloy 7b filled region on the side where the lead-in wire 9 is connected and a cavity 8 region where the inner wall surface (metal surface) of the cylindrical cup 7a is exposed.

The cold cathodes 7 and 7'having the above-mentioned structure are configured such that the bottom portions of the cylindrical cups 7a are connected to and held by the lead-in wires 9 sealed and led out at both ends of the glass tube 5, respectively. It is configured to function as.

When a required voltage was applied to the cold cathode low-pressure discharge lamp having the above-mentioned structure to perform lighting and operation, no "fluttering" of the glow occurred and no flicker phenomenon was observed in the electrode parts 7, 7 '. It was Further, the spread of the glow is prevented, the metal spatter on the glass tube 5 is suppressed, and the rise of the tube wall temperature is reduced. Furthermore, the electrode parts 7, 7'are kept warm by the ceramic insulator layer 7c, and the heat retaining effect suppresses heat dissipation to the glass tube wall side, so that the internal temperature of the electrode parts 7, 7'becomes high and electrons are absorbed. It was also confirmed that the cathode was easily discharged and the cathode drop voltage was lowered.

Embodiment 2 FIG. 2 is a sectional view showing an example of the essential structure of a cold cathode low pressure discharge lamp of this embodiment. In FIG. 2, 5 is a glass tube having an inner wall surface provided with a phosphor layer 6 that emits light upon stimulation with ultraviolet rays, and a rare gas sealed glass tube having an outer diameter of 3.0 mm and an inner diameter of 2.0 mm. Is a pair of cold cathodes enclosed at both ends of the cold cathode. Here, the cold cathode 7,
7'is, for example, a cylindrical cup 7a made of Ni and having an outer diameter of 1 mm and a length of 3 mm.
Mixtures of mg of mercury alloy powder and getter material 7
b ′ and a thickness of 20 to 5 covering the outer peripheral surface of the cylindrical cup 7a
It is composed of an insulator layer 7c (ceramics such as aluminum oxide) of about 0 μm, and the mixture 7b ′ of the mercury alloy powder and the getter material leaves a cavity 8 on the open end side of the cylindrical cup 7a. In addition, the emitter layer 10 is formed on the inner wall surface of the cavity 8. That is, the inside of the cylindrical cup 7a is filled with a mixture 7b 'of the mercury alloy and the getter material on the side connected to the lead-in wire 9 and the cavity portion 8 area for exposing the inner wall surface (metal surface) of the cylindrical cup 7a. Further, about 2 mg of an emitter such as BaO is deposited on the inner wall surface (metal surface) of the cavity portion 8 of the cylindrical cup 7a.

The cold cathodes 7 and 7'having the above structure are connected to and held at the bottom side of the cylindrical cup 7a by the lead-in wires 9 sealed and led out at both ends of the glass tube 5, respectively. It is configured to function as an electrode.

When a required voltage was applied to the cold cathode low-pressure discharge lamp having the above-mentioned structure to perform lighting and operation, scattering of electrode constituent substances was suppressed / reduced, and the emitter was activated by the getter material, The discharge is made only from the inner wall surface of the open cavity 8 of the cold cathode 7, 7 ', the hollow effect is easily obtained, the cathode drop voltage is also reduced, and it functions as a cold cathode low-pressure discharge lamp with high luminous efficiency. It was confirmed to do. Further, in this cold cathode low pressure discharge lamp, no flickering phenomenon is observed in the electrode parts 7, 7'even in the low current region, the spread of the glow is prevented, the metal spatter on the glass tube 5 is suppressed, and the tube wall temperature is suppressed. Not only is the rise of the ceramic insulator layer 7c reduced, but also the electrode parts 7, 7'formed by the ceramic insulator layer 7c.
The heat-retaining effect of 1 raises the internal temperature of the electrode parts 7 and 7 ', which facilitates the emission of electrons.

The present invention is not limited to the above embodiments, but various modifications can be made without departing from the spirit of the invention. Depending on the application and standard of the cold cathode low-pressure discharge lamp, such as the outer diameter and length of the glass tube that forms the arc tube, the material of the cylindrical cup that constitutes the cold cathode, etc., the dimensions and materials other than those mentioned above may be changed as appropriate. It can be implemented in the form.

[0023]

As can be seen from the above description, according to the present invention, so-called glow "flicker" does not occur,
Provided is a cold cathode low-pressure discharge lamp in which the flicker phenomenon in the cold cathode is completely eliminated. In addition, the spread of the glow is also prevented, and the scattering and spattering of the electrode constituent substances is suppressed, while the cold cathode has an increased internal temperature due to the heat insulation effect of the insulator layer, so that electrons are easily emitted and the cathode drop voltage also decreases. And functions as a cold cathode low pressure discharge lamp with high lamp efficiency. That is, it is possible to provide a cold cathode low-pressure discharge lamp that functions as a long-lifetime light source that can obtain a stable and high-quality display while contributing to downsizing or thinning of a backlight unit of a liquid crystal display device.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration example of a main part of a cold cathode low pressure discharge lamp according to the present invention.

FIG. 2 is a cross-sectional view showing another configuration example of the main parts of the cold cathode low-pressure discharge lamp according to the present invention.

FIG. 3 is a cross-sectional view showing the configuration of a main part of a conventional cold cathode low pressure discharge lamp.

[Explanation of symbols]

 1, 6 ...... Phosphor layer 2, 5 ...... Glass tube 2a ...... Glass tube depression 3, 3 ', 7, 7' ... Cold cathode 3a, 7a ... Cylindrical cup 3b, 7b ... Mercury alloy powder 4,9 ... Introduction line 7b '... Mercury alloy-Ketter mixture 7c ... Insulator layer 8 ... Cylindrical cup cavity 10 ... Emitter layer

Claims (3)

[Claims] 1. A cold cathode low-pressure discharge lamp comprising a glass tube having a phosphor layer on its inner wall surface and sealing a rare gas, and a pair of cold cathodes sealed at both ends of the glass tube, respectively. The cold cathode main body is a metallic cylindrical cup having an outer peripheral surface having an opening on the opposite surface and an insulating layer coated on the cylindrical cup, and a filling tip end surface located inside the opening end in the cylindrical cup. A cold cathode low pressure discharge lamp, comprising: a mercury alloy filled in a shape forming a part. 2. 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 sealed at both ends of the glass tube, respectively. The cold cathode body is a metallic cylindrical cup having an outer peripheral surface with an opening facing the insulating layer and an insulating layer coated on the cylindrical cup, and a filling tip surface is located inside the opening end in the cylindrical cup. A cold cathode low-pressure discharge lamp, comprising: a mercury alloy filled in a shape to form a cathode and an emitter layer deposited on an inner wall surface of the hollow portion of the cylindrical cup. 3. The cold cathode low pressure discharge lamp according to claim 1 or 2, wherein the insulator layer covering the outer peripheral surface of the metal cylindrical cup is a ceramic layer.