KR20100019359A - Cold cathode fluorescent lamp and method for manufacturing the same - Google Patents

Abstract

PURPOSE: A fluorescent lamp with a cold cathode and a method for manufacturing thereof are provided to improve a sputtering resistance while a high tube current is applied, and to extend a life expectancy of an electrode. CONSTITUTION: A fluorescent lamp with a cold cathode comprises: a transparent tube(2) which is shielded with sealing members, including a fluorescent layer on the surface of an inner wall, an inert gas, and mercury; electrodes(7) installed in both ends of the transparent tube; and lead wires(9) connected to the electrodes while passing through the sealing members. The electrodes are forming a micro structure composed with steel, a ferreous alloy, and crystal particles with an average diameter of a 4.9 micrometer.

Description

COLD CATHODE FLUORESCENT LAMP AND METHOD FOR MANUFACTURING THE SAME

The present invention has been made in accordance with the priority claimed in Japanese Patent Laid-Open No. 2008-204565, and all the contents described in the parent application are included herein.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cold cathode fluorescent lamps and methods of manufacturing the same, and more particularly to cold cathode fluorescent lamps having extended lifetime by improving sputtering resistance of electrodes even when high tube currents are applied, and cold cathode fluorescent lamps thereof. It relates to a method of manufacturing a lamp.

Cold cathode fluorescent lamps are characterized by high brightness, excellent color rendering characteristics, long life, low power consumption, and other characteristics, and thus are suitable for backlights, facsimiles and other similar devices used in televisions, computers, and other liquid crystal display devices. It is frequently used for image reading light sources in Era, eraser light sources in copiers, and various display purposes. This type of cold cathode fluorescent lamp operates as follows, i.e., provided in the vicinity of both ends of a transparent tube made of glass or any other suitable material, in which it contains noble gas and mercury in a closed manner. The remaining voltage is applied to the electrode. The small number of electrons present in the transparent tube, which is energized, ionize the rare gas. When the ionized rare gas strikes the electrode, secondary electrons are released, thereby generating a glow discharge. Mercury irradiated with the glow discharge is excited to emit ultraviolet rays. When the fluorescent material present on the inner wall of the transparent tube receives ultraviolet light, the fluorescent material emits visible light.

The electrodes of this type of cold cathode fluorescent lamp have a cup shape because the tube voltage and power consumption can be reduced, and are arranged at both ends of the transparent tube in such a way that the openings of the cup-shaped electrodes face each other. The following reasons: low melting temperature, good workability, excellent sputtering resistance to mercury and rare gas ions and other materials, Kovar and other similarly commonly used as sealing materials Due to the good weldability to the materials and sufficient durability under tube currents in the 4-5 mA range, the electrode consists of nickel. In recent years, however, in cold cathode fluorescent lamps in large-screen, high-brightness liquid crystal display devices of televisions, in the backlight unit of the liquid crystal display device, the electrodes are durable under 5 mA tube current, excellent sputtering resistance to large loads, low work function, and low Nickel has been replaced by molybdenum or niobium as the electrode material because it requires a discharge start voltage (Japanese Patent Laid-Open No. 2004-355971).

However, since molybdenum and niobium have high melting points of 2622 ° C and 1950 ° C, respectively, it is difficult to manufacture a furnace that can completely melt such a high-melting point metal to produce an electrode. In addition, molybdenum and niobium per se are expensive, and furnaces with durability under their melting point are also expensive. Thus, electrodes composed of any of the metals described above are expensive. To overcome this problem, electrodes are typically produced by processing ingots or wires made by sintering any of the metals described above at a temperature below its melting point, eg, about 1800 ° C. do. However, electrodes produced using ingots or wires formed by melting the material at temperatures below its melting point have a structure in which raw material grains remain and the raw grains are bonded through grain boundaries. Thus, when the surface of the electrode is heated and oxidized during the manufacturing process of the cold cathode fluorescent lamp, the bonding force between the raw grains is weakened. In a cold cathode fluorescent lamp comprising an electrode thus produced, mercury and rare gas ions undesirably selectively sputter grain boundaries between the grains. Thus, the electrodes composed of molybdenum or niobium used in actual cold cathode fluorescent lamps do not have sputtering resistance and are virtually unreliable.

In addition, although molybdenum and niobium are slightly better than nickel in sputtering resistance to mercury, rare gas ions and other materials, as in the case of nickel, molybdenum and niobium interact with mercury during the operation of the lamp and contribute to light emission Sputtered molybdenum and niobium undesirably consume mercury introduced into the transparent tube because it forms amalgams that do not. Thus, the amount of mercury introduced into the transparent tube should be the amount of mercury used for light emission, in addition to the amount of mercury consumed to form amalgam. Recently, the amount of mercury introduced into the transparent tube is also preferably minimized from the viewpoint of environmental issues. Thus, there is a need for an electrode material that can reduce the amount of amalgam to be formed when the electrodes are sputtered.

Examples of main materials that do not interact with mercury to form amalgam may include iron, tungsten, and manganese. However, tungsten has a very high melting point, and therefore electrodes composed of sintered tungsten are very expensive and, therefore, are not practically suitable. In addition, manganese is not practically suitable as a major component of the electrode. Iron is virtually suitable as an electrode material. For example, a material commonly referred to as pure iron with a high iron content and a carbon content of up to about 0.02% by mass has a sputtering resistance that is similar to or less than that of nickel for mercury and neon ions, so that There is a need to improve sputtering resistance.

Japanese Laid-Open Patent Publication No. 2005-183172 is another layer composed of at least one of nickel, stainless steel, iron, aluminum, or copper, and tungsten, molybdenum, niobium, or any other suitable material disposed thereon. Reports a discharge lamp with electrodes each comprising a layer, with excellent emitter retention performance and long lifetime. Japanese Patent Laid-Open Publication No. 2005-327485 and Japanese Patent Laid-Open Publication No. 2006-073307 report cold cathode fluorescent lamps having specific structures similar to the two-layer structure described in Japanese Patent Laid-Open Publication No. 2005-183172. . However, because of the molybdenum, niobium, and other materials used at the surface of each of the electrodes, these discharge lamps are in fact problematic.

The object of the present invention is that each has excellent sputtering resistance even when high tube current is applied, forms little amalgam, hardly loads to the environment, can be easily manufactured at low cost, and long lifespan It is to provide a cold cathode fluorescent lamp comprising electrodes operating at a practical level to provide.

The inventors of the present invention have carried out intensive research, in which an electrode composed mainly of iron or iron alloy material having a microstructure consisting of iron or iron alloy crystal particles having an average diameter of 4.9 μm or less has a high tube current. It was found that even when is applied, it is excellent in sputtering resistance and hardly forms amalgam when the electrode is used in a cold cathode fluorescent lamp. The present invention has been obtained based on the above findings.

That is, the present invention provides a transparent tube comprising a fluorescent layer provided on an inner wall surface and containing rare gas and mercury, both ends of the transparent tube being shielded by sealing members; Electrodes provided in the vicinity of both ends of the transparent tube; And a cold cathode fluorescent lamp having lead wires connected to the electrodes and penetrating the sealing members, wherein each of the electrodes is made of iron or iron alloy crystal particles having an average diameter of 4.9 μm or less. It consists of an iron or iron alloy material with a microstructure.

That is, the present invention relates to a method of manufacturing a cold cathode fluorescent lamp according to the cold cathode fluorescent lamp described above, the method comprising: forming a cast made of iron or iron alloy material; And forging or rolling the cast by straining in multiple directions to form an electrode having a microstructure of iron or iron alloy crystal grains having an average diameter of 4.9 μm or less. .

The cold cathode fluorescent lamps of the present invention each have excellent sputtering resistance even when a high tube current is applied, hardly form amalgam, impose little load on the environment, and can be easily manufactured at low cost. And electrodes that operate at a practical level providing long life.

According to the present invention, each has excellent sputtering resistance even when a high tube current is applied, hardly forms amalgam, imposes little load on the environment, can be easily manufactured at low cost, and has a long service life. It is possible to provide a cold cathode fluorescent lamp comprising electrodes operating at a practical level to provide.

The cold cathode fluorescent lamp of the present invention comprises a transparent tube comprising a fluorescent layer provided on an inner wall surface and containing rare gas and mercury, both ends of the transparent tube being shielded by sealing members; Electrodes provided in the vicinity of both ends of the transparent tube; And lead wires connected to the electrodes and passing through the sealing members. Each of the electrodes is composed of an iron or iron alloy material having a micro structure composed of iron or iron alloy crystal particles having an average diameter of 4.9 μm or less.

The transparent tube used in the cold cathode fluorescent lamp of the present invention may be composed of silicate glass, borosilicate glass, zinc borosilicate glass, lead glass, soda glass, or any other material that transmits visible light. The transparent tube may have a straight, curved, or any other suitable shape. The diameter of the tube may range in any size, for example 1.5 to 6.0 mm. The thickness of the transparent tube may be appropriately selected depending on the intended purpose, but when the bore diameter described above is used, it is preferably in the range of 0.15 to 0.60 mm.

The fluorescent layer is provided on almost all of the inner wall surface of the transparent tube. The fluorescent layer contains a fluorescent material which is excited by ultraviolet rays emitted from mercury described later and emits visible light. Any fluorescent material that emits light having the intended wavelength can be selected. Such fluorescent materials may be halophosphates, rare earth compounds, and other suitable fluorescent materials. Appropriate combinations of these fluorescent materials can be used to emit white light. It is preferable that the thickness of a fluorescent layer is 11-35 micrometers.

Mercury, which generates ultraviolet light when discharge is applied, and a rare gas appropriately selected from argon, xenon, neon, and other suitable elements are introduced into the transparent tube. The discharged electrons generated in the transparent tube collide with mercury atoms, which produce ultraviolet light with 253.7 nm and other wavelengths, which in turn excite the fluorescent material. The amount of mercury and rare gas to be introduced is determined during the operation of the fluorescent lamp in such a way that the vapor pressure of mercury is, for example, in the range of 1 to 10 Pa, and the pressure of the rare gas is, for example, in the range of 5000 to 11000 Pa. It is preferable.

Each of the electrodes provided at both ends of the transparent tube consists of an iron or iron alloy material (hereinafter sometimes referred to as electrode material) having a microstructure consisting of iron or iron alloy crystal grains having an average diameter of 4.9 μm or less. . The electrode material may contain only iron, but preferably contains carbon. The above-described electrode material containing mainly iron has a melting point lower than the melting point of molybdenum, niobium, or other elements, and the contained carbon further lowers the melting point. Thus, the lead wire can be connected to the electrode at a lower temperature, whereby the deterioration of the lead wire can be reduced during the connecting operation. When the lead wire is composed of, for example, a cobar, the electrode material has a melting point similar to that of the cobar. In addition, the electrode material has a microstructure. Thus, even when a high tube current, for example 12 mA, is applied, the resulting electrode has excellent sputtering resistance.

The average diameter of the crystal grains at the electrode can be determined from the particle diameter determined by a comparison method in which an optical microscope is used to observe the electrode surface that has experienced acid etching. In detail, the comparison method is performed according to the method described in "An Introduction to Metallic Materials and Textures", p189-193, edited by Japan Society for Heat Treatment Technology and published by Taiga Publishing. In detail, in an 80 mm diameter circle on a micrograph obtained by enlarging a view of a real field of 0.8 mm diameter under an optical microscope, the crystal grains in that circle are standard charts to find the corresponding particle size number. Compared with the crystal grains in. Thus, an average particle diameter is obtained. For example, when a particle having an average diameter in the electrode image obtained by using an optical microscope corresponds to a particle of size number 5, the average particle diameter is 4.9 mu m.

The electrode material is obtained by cooling the melt mainly containing iron or iron alloy. If the electrode material contains carbon, the carbon present in the iron or iron alloy is in the form of a solid solution (ferrite, austenite, and martensite), graphite (graphite), or iron carbide (cementite). . Graphite is a carbon mineral having a hexagonal crystal phase, and cementite is iron carbide Fe ₃ C in which iron and carbon are bonded to each other. The solid solution described herein is an interstitial solid solution in which a trace of carbon atoms penetrates the gap between iron atoms in the crystal lattice. The stable structure of the invasive solid solution at high temperature is austenite (face-centered cubic lattice structure), while the stable structure of the invasive solid solution at room temperature is ferrite (body-centered cubic lattice structure). to be. When a high temperature solid solution having an austenitic structure experiences rapid cooling (quenching), a very hard but brittle martensite (central cubic lattice structure) is obtained. If the resulting martensite is reheated and kept heated for a fixed period of time, then slowly cooled (tempered), very soft tempered martensite can be obtained. Whether the carbon atoms contained in the electrode material take the form of a solid solution, graphite, or cementite, that is, the cooling rate (cycle) in which the melt containing iron or iron alloy is cooled, the iron or iron alloy contained It depends on the presence of other elements, the carbon content, the thickness of the resulting cast obtained by cooling the melt, and other conditions. The conditions described above can be adjusted so that the electrode material contains carbon in the desired form.

The electrode material preferably contains carbide particles, in particular iron carbide (cementite) particles, in the iron or iron alloy crystal grains. The carbon content in the electrode material is preferably in the range of 0.08% by mass to 1.4% by mass, more preferably in the range of 0.18% by mass to 0.68% by mass. If the carbon content in the electrode material is within this range, the carbon atoms tend to combine with iron to form iron carbide, and the electrode material is excellent in flowability when melted and then the electrode material when cooled It has a hardness that makes it easy to process. The resulting electrode also has excellent sputtering resistance to rare gas ions even when a current higher than 12 mA is applied. Thus, the life of the cold cathode fluorescent lamp is extended.

The average diameter of the iron carbide particles is preferably 95 nm or less. The average particle diameter obtained using a method similar to the method for measuring the microstructure described above can be used as the diameter of the iron carbide particles.

The above-mentioned electrode material preferably contains at least one of molybdenum, manganese, chromium, and silicon together with iron or as an iron alloy. Any of molybdenum, manganese, or chromium keeps iron carbide stable, prevents iron from oxidizing, improves quenching effects, and densifies microstructures to increase hardness. In addition, manganese combines with sulfur contained in iron or iron alloys to form manganese sulfate, and manganese not bound to sulfur forms carbides that prevent black lead from separating.

Silicon is the element that most graphitizes carbon and strongly decomposes iron carbide. However, silicon can improve the flowability of the molten electrode material. Thus, the rate at which the electrode material containing silicon is cooled is high, and if the resulting electrode is thickly defined, the amount of graphitized carbon is reduced.

The total amount of molybdenum, manganese, chromium, and silicon contained in the electrode material is preferably in the range of 0.3% by mass to 3.5% by mass, more preferably in the range of 0.6% by mass to 2.1% by mass. If the total content of these atoms is within this range, the iron carbide contained in the electrode material can be stable and the fluidity of the molten electrode material can be maintained. Thus, the electrode can be easily formed.

The electrode composed of the above-mentioned electrode material may be shaped into a plate, but a cup-shaped electrode is preferable because it can reduce tube voltage and power consumption. It is also preferred that the electrodes are arranged in the vicinity of both ends of the transparent tube in such a way that the openings of the cup-shaped electrodes face each other. The cup-shaped electrode can be manufactured by forming a plate-shaped ingot made of the above-described electrode material, cutting the ingot into members, and joining the members. Alternatively, the cup-shaped electrode is preferably formed by cutting the circular plate from the plate-shaped ingot and pressing the circular plate onto the cup-shaped plate. Alternatively, the cup-shaped electrode forms a wire composed of the electrode material described above, cuts a wire segment having a desired length from the wire, and hammers the cutting surface in the axial direction to recess ( by forming a recess) or a cup shape, it can be easily formed. The procedure described above is referred to as header operation. The cup shape may be appropriately selected in consideration of the inner diameter of the transparent tube and the output of the lamp. For example, the outer diameter of the cup may be in the range of 1.05 to 2.75 mm, and the length of the cup may be in the range of 3 to 8 mm.

The lead wire is connected to the electrode described above, and connects the electrode to an external power source. One end of the lead wire is fused with the bottom of the electrode, and the other end passes through the sealing member for sealing the end of the transparent tube and protrudes from the sealing member. The lead wire is preferably heat resistant to reduce deterioration of the lead wire due to the heat generated when the lead wire is fused with the electrode and the heat generated when the sealing member is closely attached to the end of the transparent tube. In addition, the lead wire preferably has thermal conductivity such that heat generated at the electrode during the operation of the lamp is efficiently dissipated from the transparent tube. Within the transparent tube, the lead wire may be formed from a cobar wire having a double structure in which the copper core wire is coded with a cobar or any other suitable wire, while the dumet wire or any other suitable wire is outside the transparent tube. Used in

Sealing members, such as a stem, which seals both ends of the transparent tube containing rare gas and mercury described above, function as members through which the lead wires penetrate and fix the electrode through the lead wires. For example, the sealing members can be formed of glass beads or made of cobar.

The cold cathode fluorescent lamp of the present invention may include a protective layer between the fluorescent layer and the transparent tube. The protective layer prevents ultraviolet radiation emitted from mercury from leaking out of the transparent tube and prevents mercury from reacting with materials separated from the transparent tube. The protective layer may be composed of yttrium oxide, aluminum oxide, or any other suitable metal oxide.

The process for producing the cold cathode fluorescent lamp described above comprises a cast consisting of a molten material obtained by melting iron or iron alloy with carbon, molybdenum, manganese, chromium, silicon, or any other suitable element as required, That is, manufacturing the ingot or wire, and forging or rolling the resulting ingot or wire to form an electrode having a microstructure containing crystal grains having an average diameter of 4.9 μm or less, thereby resulting in multiple directions. Straining the ingot or wire. Thus, a cold cathode fluorescent lamp can be produced.

Specifically, the method of forming an electrode is characterized in that when the electrode material to be used has an iron atom content of at least 96 mass% and a carbon content of 0.5 mass%, for example, the electrode material is melted at 1500 ° C. to provide a cast. And deformation processing the resulting cast. In detail, the deformation processing can be performed as follows, that is, the cast block is strained in multiple directions by hot forging or hot rolling to form a coiled material. The resulting coiled material is rinsed with acid and then annealed to remove any strain and improve malleability. Thereafter, the coiled material is extended while experiencing hardness adjustment. For example, the coiled material is shaped into a wire having a diameter, for example a diameter in the range of 1 to 2.6 mm, depending on the electrode to be formed. In addition, the wire undergoes a header process such that the resulting wire has a desired shape, such as a cylindrical shape.

Alternatively, the cast block may be strained in a number of directions by hot forging, hot rolling, or cold rolling to form a plate having a thickness, for example, in the range of 0.1 mm to 0.2 mm, depending on the electrode to be formed. It is shaped. The resulting plate may undergo a press operation such that the plate has a desired shape, such as a cylindrical shape, or the plate is joined to form an electrode after it is cut into members. The heating temperature during deformation processing is preferably in the range of 350 to 780 ° C.

The above-described method for producing an electrode can provide an electrode having a microstructure composed of iron or iron alloy crystal particles having an average diameter of 4.9 μm or less, and the iron or iron alloy crystal particles have an average diameter of 95 nm. It contains the following iron carbide particles. After the surface of the resulting electrode is polished, the lead wire is joined with the electrode. If a cobar wire is used, resistance welding or laser welding may be used to directly integrate the electrode and the cobar wire.

Preparing a dispersant obtained by dispersing the fluorescent material in a solvent, consisting of glass or any other suitable material and having a predetermined shape for a predetermined thickness using dipping, spraying, or any other suitable method The dispersant is applied to the inner wall surface of the transparent tube and the applied dispersant is dried to form a fluorescent layer on the inner wall of the transparent tube. Thus, a fluorescent layer having a predetermined thickness is formed. The cold cathode fluorescent lamp can then be produced by placing the electrode at the end of the transparent tube, sealing the end of the transparent tube with the sealing members through which the lead wire passes, and introducing mercury and rare gases into the transparent tube. have.

As an example of the cold cathode fluorescent lamp of the present invention, a backlight of the liquid crystal panel shown in FIG. 1 may be provided as an example. The cold cathode fluorescent lamp 1 shown in FIG. 1, which is a schematic cross-sectional view, comprises a glass tube 2 composed of borosilicate glass, both ends of which are glass beads 3 which are sealing members. Is sealed in a sealed manner. The outer diameter of the glass tube 2 is in the range of 1.5 to 6.0 mm, preferably in the range of 1.5 to 5.0 mm. A fluorescent layer 4 is provided on the inner wall surface of the glass tube 2 along almost all the lengths of the glass tube 2. A predetermined amount of rare gas and mercury are introduced into the inner space 5 surrounded by the inner wall surface of the glass tube 2, and the inner pressure is reduced to about several tens of atmospheric pressure. The cup-shaped electrodes 7 are arranged in the long axis direction at both ends of the glass tube 2 in such a manner that the openings 10 face each other, as shown in the perspective view of FIG. Each of the cup-shaped electrodes 7 has a microstructure containing iron or iron alloy crystal particles having an average diameter of 4.9 μm or less. The lead wire 9 made of a cobar or any other suitable material has one end of the lead wire 9 welded to the bottom 8 of the electrode 7 and the other end penetrating the corresponding portion of the glass bead 3. It is connected to each of the cup-shaped electrodes 7 in a manner that protrudes from the glass beads.

The above-described cold cathode fluorescent lamps comprise electrodes composed of iron or iron alloy material having a microstructure each consisting of iron or alloy crystal grains having an average diameter of 4.9 μm or less, in particular each of which has a diameter In the form of iron carbide particles of 95 nm or less, the carbon atoms contain content in the range of 0.08% by mass to 1.4% by mass. Thus, cold cathode fluorescent lamps are excellent in sputtering resistance, form little amalgam, and impose little load on the environment.

[Examples]

The invention will be described in more detail below with reference to the examples.

Example 1

The raw material obtained by mixing iron with graphite and other elements in the ratio shown in Table 1 was melted at 1400 ° C. The molten material was injected into a die containing a cavity, and the injected material at a temperature in the range of 800 to 900 ° C. was immersed in water and quenched at room temperature. The coiled material was then strained in multiple directions by repeating hot forging and hot rolling at 500 ° C. and drawing and other processes to produce a wire having a diameter of about 0.2 mm. The wire experienced header work such that a cup-shaped electrode with an outer diameter of 1.7 mm and a length of 5 mm was produced. Cobar wire with a diameter of 0.8 mm was welded to the bottom of the resulting electrode and integrated with the bottom.

The average diameter of the iron crystal particles of the electrode was measured by using a comparison method. The average diameter of the iron crystal grains was 2 μm.

The fluorescent material was applied onto the inner wall surface of the glass tube having a diameter of 2.0 mm so that the applied fluorescent material had a thickness of about 18 μm. The electrodes to which the cobar wire was fused were placed at both ends of the glass tube in such a manner that the openings of the electrodes faced each other, and the glass beads through which the cobar wire penetrated were used to seal both ends of the glass tube. Thereafter, mercury and rare gas were introduced into the glass tube. Thus, a cold cathode fluorescent lamp was produced.

The resulting cold cathode fluorescent lamp was operated at a tube current of 10 mA and the performance of sputtering resistance was observed by examining the amount of wear of the cup-shaped electrodes. Sputtering resistance was evaluated by examining the amount of wear of the cup-shaped electrodes according to the following criteria. Table 1 shows the evaluation results.

A: The cup-shaped electrodes are slightly worn out.

B: Cup-shaped electrodes are worn, but can be used sufficiently.

C: Cup-shaped electrodes are worn and can only be used.

D: Cup-shaped electrodes are very worn and cannot be used.

[Examples 2 to 4]

A cold cathode fluorescent lamp was prepared in the same manner as in Example 1, except that the raw materials shown in Table 1 were used. The resulting cold cathode fluorescent lamp was evaluated in terms of sputtering resistance in the same manner as in Example 1. Table 1 shows the evaluation and the results.

[Comparative Example]

A cold cathode fluorescent lamp was prepared in the same manner as in Example 1, except that the raw materials shown in Table 1 were used. The resulting cold cathode fluorescent lamp was evaluated in terms of sputtering resistance in the same manner as in Example 1. Table 1 shows the evaluation results.

It is evident that each of the cold cathode fluorescent lamps of the present invention comprises electrodes with excellent sputtering resistance even when the tube current induces a high voltage, and thus is excellent in durability.

The cold cathode fluorescent lamp of the present invention has excellent sputtering resistance even when a high tube current is applied, forms little amalgam, hardly loads the environment, and can be easily manufactured at low cost, and long Operate at a practical level that provides life. Cold cathode fluorescent lamps are suitably used and useful as backlights used in televisions, computers, and other liquid crystal display devices, image reading light sources in facsimile and other similar devices, erasure light sources in copiers, and various display purposes.

1 is a schematic block diagram showing an example of a cold cathode fluorescent lamp of the present invention.

2 is a perspective view showing an electrode of an example of the cold cathode fluorescent lamp of the present invention.

* Description of the symbols for the main parts of the drawings *

1: cold cathode fluorescent lamp

2: glass tube (transparent tube)

3: glass beads

4: fluorescent layer

5: interior space

7: electrode

8: bottom

9: lead wire

10: opening

Claims (7)

A transparent tube comprising a fluorescent layer provided on an inner wall surface and containing rare gas and mercury, wherein both ends of the transparent tube are shielded by sealing members; Electrodes provided in the vicinity of both ends of the transparent tube; And Lead wires connected to the electrodes and penetrating the sealing members, Wherein each of the electrodes is made of an iron or iron alloy material having a microstructure made of iron or iron alloy crystal grains having an average diameter of 4.9 μm or less. The method of claim 1, And said iron or iron alloy material contains carbon in the range of 0.08 mass% or more to 1.4 mass% or less. The method of claim 1, And the iron or iron alloy material contains carbon in the form of carbide particles in the iron or iron alloy crystal grains. The method of claim 3, wherein And the carbide particles have an average diameter of 95 nm or less. The method of claim 3, wherein And said carbide particles are comprised of iron carbide. The method of claim 1, And the iron or iron alloy material contains at least one of molybdenum, manganese, chromium and silicon in a range of 0.3 mass% or more and 3.5 mass% or less. As a method of manufacturing the cold cathode fluorescent lamp according to any one of claims 1 to 6, Forming a cast consisting of iron or iron alloy material; And Forging or rolling the cast by straining in a plurality of directions to form an electrode having a microstructure of iron or iron alloy crystal grains having an average diameter of 4.9 μm or less. Lamp manufacturing method.

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