JP2010040438A - Cold-cathode fluorescent lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cold-cathode fluorescent lamp which has superior sputtering-resistant characteristics, even when a tube current of high current is applied and which restrains the formation of amalgams and has a light environmental load, and can easily, effectively and inexpensively manufacture electrodes of long service life of practical level. <P>SOLUTION: In the cold-cathode fluorescent lamp having a transparent tube, wherein a phosphor layer is arranged on an inner wall surface and a rare gas and mercury are retained in the inside, and both the ends are sealed by a sealing member, the electrode arranged in the vicinity of both ends inside the transparent tube, and a lead wire connected with the electrode and arranged by passing through the sealing member, the electrode has a base material formed by iron or an iron alloy material, and a rustproof film on the surface of the base material; and the rustproof film includes one or two kinds of elements selected from between nickel and chromium. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cold cathode fluorescent lamp, and more particularly, to a cold cathode fluorescent lamp that can be manufactured efficiently by reducing the amount of mercury used and preventing rust of electrodes during manufacture.

  Cold cathode fluorescent lamps for backlights used in liquid crystal display devices such as televisions and computers, light sources for reading facsimiles, light sources for copy machine erasers, various displays, etc. have high brightness, high color rendering, long life, Widely used because of its low power consumption and the like. In this type of cold cathode fluorescent lamp, a voltage is applied to electrodes provided in the vicinity of both ends of a transparent tube such as glass in which a rare gas and mercury are kept airtight inside, so that it is slightly present in the transparent tube. The noble gas is ionized by electrons, and the ionized noble gas collides with the electrode to emit secondary electrons to cause glow discharge, thereby exciting mercury and emitting ultraviolet rays. Visible light is emitted from the phosphor provided on the inner wall of the transparent tube that has received the ultraviolet rays.

  As the electrode of this type of cold cathode fluorescent lamp, a cup-shaped one that can reduce the tube voltage and power consumption is used, and the cup-shaped openings are respectively disposed at both ends of the transparent tube so as to face each other. Be placed. The electrode material is low in melting temperature, easy to process, excellent in spatter resistance against mercury, rare gas ions, etc., and well welded with Kovar or the like generally used for sealing members. Nickel has been used because it has durability enough to withstand use at a tube current of ˜5 mA. However, a cold cathode fluorescent lamp of a backlight unit of a large-screen television and a high-brightness liquid crystal display device in recent years is required to have durability against a tube current of 5 mA or more. On the other hand, molybdenum, niobium, etc., which are excellent in sputtering resistance, have a low work function, and can reduce the discharge start voltage, are used instead of nickel (Patent Document 1).

  However, molybdenum and niobium have high melting points of 2622 ° C. and 1950 ° C., respectively, and it is difficult to make a heating furnace capable of producing electrodes by completely melting such high melting point metals. In addition to being expensive in itself, molybdenum and niobium are expensive, and furnaces having durability at the high melting point temperature of such metals are expensive, and electrodes using these metals are expensive. In general, an electrode is manufactured by processing an ingot or a strand formed by sintering these metals at a high temperature of about 1800 ° C. However, ingots and wires formed by melting at a temperature that does not reach the melting point, the boundaries of the raw material particles remain, and in the electrodes made using such ingots and strands, the boundaries of the raw material particles Sputtering proceeds selectively. For this reason, an electrode made of molybdenum or niobium as a raw material does not have sputtering resistance against mercury or rare gas ions that can be applied to a cold cathode fluorescent lamp at a practical level. Molybdenum and niobium are slightly superior to nickel in sputtering resistance against mercury and rare gas ions.

  However, since nickel, molybdenum, and niobium continue to form amalgam that does not contribute to light emission by reacting with mercury during the operation of the lamp, mercury introduced into the transparent tube is consumed. For this reason, the amount of mercury introduced into the transparent tube is an amount obtained by adding the amount of mercury consumed for amalgam formation to the amount of mercury used for light emission. Due to environmental problems in recent years, it is desirable to minimize the amount of mercury introduced into the transparent tube. Currently, it is necessary to reduce the amount of mercury used from 4 mg to 5 mg per lamp to 2 mg or less. Therefore, there is a demand for an electrode material that can suppress the formation of amalgam during electrode sputtering.

  The main materials that do not form mercury and amalgam include iron, tungsten, and manganese. However, tungsten has a very high melting point and is generally only a sintered material to be used as an electrode material, which makes it extremely expensive as an electrode. It is unsuitable for practical use. Further, manganese is not practically suitable as a main component of the electrode. Although iron is practically possible as an electrode material, for example, rust increases as the iron content increases, such as an iron material generally referred to as pure iron with a carbon content of up to about 0.02% by mass. There is a problem that is likely to occur.

  As an electrode of a fluorescent lamp using an iron material, an electrode having a layer made of tungsten, molybdenum, niobium or the like on a layer made of at least one of nickel, stainless steel, iron, aluminum, and copper is provided. Discharge lamp (Patent Document 2) excellent in performance and long life, base material made of nickel, nickel alloy, iron, iron alloy, tungsten and molybdenum, and one material selected from rhodium, palladium and these alloys An electrode for a cold cathode fluorescent lamp made of an electrode surface made of (Patent Document 3), a base material made of nickel, nickel alloy, iron, iron alloy, tungsten and molybdenum, a surface layer made of tungsten or molybdenum, and a zinc alloy An electrode for a cold cathode fluorescent lamp having a bonding layer (Patent Document 4) has been reported.

However, rhodium, palladium, tungsten, molybdenum, etc. provided on the surface of these electrodes have problems in practical use. If these surface layers are not provided, the surface of the base material is rusted by the time of manufacturing the lamp. If an electrode with rust is generated and a lamp is attached to the lamp, there is a problem that mercury adheres to the rusted portion and consumes a large amount of mercury.
JP 2004-355971 A JP 2005-183172 A JP 2008-060056 A JP 2008-060057 A

  An object of the present invention is to provide an electrode of a practical level that has excellent sputtering resistance even when a high tube current is applied, suppresses the formation of amalgam, has a low environmental load, and has a long service life. An object of the present invention is to provide a cold cathode fluorescent lamp capable of preventing rust, producing inexpensively and efficiently.

  As a result of diligent research, the present inventor has formed an iron or iron alloy material, in particular, an iron or iron alloy material having a carbon content of 0.5% by mass or less and further containing 99.5% by mass or more of iron. The electrode having the base material and the anticorrosive film containing nickel or chromium, when applied to a cold cathode fluorescent lamp, can suppress the formation of amalgam more than before, and the amount of mercury used is reduced accordingly. The knowledge that it can reduce and can prevent rust prevention of an electrode was acquired. Based on this finding, the present invention has been completed.

  That is, the present invention provides a transparent tube in which a phosphor layer is provided on the inner wall surface, holds a rare gas and mercury inside, and is sealed at both ends by a sealing member, and is provided near both ends of the inside of the transparent tube. A cold cathode fluorescent lamp having a formed electrode and a lead wire connected to the electrode and penetrating through a sealing member, wherein the electrode is formed of iron or an iron alloy material, and the surface of the substrate The present invention relates to a cold cathode fluorescent lamp characterized by comprising a rust preventive film, wherein the rust preventive film contains one or more elements selected from nickel and chromium.

  The cold cathode fluorescent lamp of the present invention has an excellent sputtering resistance even when a high tube current is applied, suppresses the formation of amalgam, has a low environmental load, and has a long-life practical electrode. The electrode can be rusted and easily manufactured at low cost and efficiently.

  The cold cathode fluorescent lamp of the present invention includes a transparent tube having a phosphor layer on the inner wall surface, holding a rare gas and mercury therein, and sealed at both ends by a sealing member, and both end portions inside the transparent tube. In a cold cathode fluorescent lamp having an electrode provided in the vicinity and a lead wire connected to the electrode and provided through the sealing member, the electrode is made of iron or an iron alloy material, It has a rust preventive film on the substrate surface, and the rust preventive film contains one or more elements selected from nickel and chromium.

  The transparent tube used in the cold cathode fluorescent lamp of the present invention is any material that transmits visible light, such as glass such as silicate glass, borosilicate glass, zinc borosilicate glass, lead glass, and soda glass. It may be. The shape may be either a straight tube type or a curved type. The tube diameter may be any, and examples thereof include 1.5 to 6.0 mm. The thickness of the transparent tube can be appropriately selected depending on the purpose of use, but it is preferably 0.15 to 0.60 mm for the above-mentioned diameter.

  On the inner wall surface of the transparent tube, a phosphor layer is provided over almost the entire surface. The phosphor layer contains a phosphor that emits visible light when excited by ultraviolet rays emitted by mercury, which will be described later. Such phosphors can be selected to emit light having a target wavelength depending on the purpose of use, and for example, halophosphate phosphors, rare earth phosphors, and the like can be used. These can be used in appropriate combination to emit white light. The thickness of the phosphor layer is preferably 11 μm or more and 35 μm or less.

  Mercury that generates ultraviolet rays by discharge is introduced into the transparent tube, a rare gas appropriately selected from argon, xenon, neon, etc. is introduced, and the discharge electrons generated in the transparent tube collide with mercury atoms, Ultraviolet light including 253.7 nm for exciting the phosphor is generated. The amount of mercury or rare gas to be introduced is such that when the fluorescent lamp is turned on, the vapor pressure of mercury is, for example, 1 to 10 Pa, and the pressure of the rare gas is, for example, 5000 Pa to 11000 Pa. preferable.

  The electrodes provided at both ends inside the transparent tube have a base material formed of iron or an iron alloy material (hereinafter also referred to as an electrode material) and a rust preventive film on the surface of the base material. The electrode material may contain a small amount of carbon but contains iron as a main component. Since such an electrode material has iron as a main component, it has a lower melting point than materials containing molybdenum, niobium, etc., has excellent processability, and the lead wire is connected to the obtained electrode at a lower temperature. Therefore, deterioration of the lead wire can be suppressed. For example, when Kovar is used for the lead wire, it has a melting point in the same temperature range and has a fine structure, so even when a high tube current, for example, 10 mA is applied to the obtained electrode, it is excellent. It has high sputtering resistance.

  In addition, since the electrode material suppresses the formation of amalgam by reacting with the mercury by sputtering with the electrode base material, the greater the content of iron that does not form amalgam, the more specifically, 99.5. The content is preferably at least mass%, and the carbon content is preferably at most 0.5 mass%. However, if the iron content in the electrode material is 99.999% by mass or more, the cost of refining iron increases rapidly, and the price of the electrode material becomes remarkably high. The amount is preferably 99.5% by mass or more and 99.999% by mass or less.

  The electrode material may contain any one of molybdenum, manganese, chromium, or silicon, or two or more of them together with iron or as an iron alloy.

  The base material formed of iron or an iron alloy preferably has a fine structure with an average crystal grain size of 4.9 μm or less. When the average crystal grain size is 4.9 μm or less, the cold cathode fluorescent lamp has excellent sputtering resistance against mercury and rare gas ions.

  Here, the average particle diameter of the crystal particles of the electrode can be obtained from the particle diameter obtained by a comparative method using optical microscope observation of the electrode surface etched with an acid. Specifically, in accordance with the method described in Japan Heat Treatment Technology Association edited by Oga Publishing, "Introductory Metal Materials and Structures" (P189-193), a circular optical with an actual visual field diameter of 0.8 mm. In a circle with a diameter of 80 mm of a photographic print with a microscope of 100 times, the corresponding particle size number is determined in comparison with a standard drawing to obtain an average particle size. For example, from the image obtained by the optical microscope of the electrode, the particle diameter is slightly smaller than the particle size number 5, and an average value of 4.9 μm can be obtained.

The electrode material is obtained by cooling a melt containing iron or an iron alloy as a main component. When the electrode material contains a carbon atom, the carbon atom is a solid solution (ferrite) in the iron or iron alloy. , Austenite, martensite), graphite (graphite), iron carbide (cementite). Here, 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. The solid solution is an interstitial solid solution in which very few carbon atoms have entered the gaps between the atoms of the iron crystal lattice. At high temperatures, the austenite (face-centered cubic lattice structure) has a stable structure. (Centric cubic structure) is a stable structure, but by quenching (quenching) the high-temperature solid solution of the austenite structure, it becomes a very hard and brittle martensite (body-centered tetragonal lattice structure). After heating and holding for a certain period of time, it is cooled (tempered) to obtain a tempered martensite with high toughness. The solid solution may have these structures. Whether the carbon atom contained in the electrode material takes the form of a solid solution, graphite or cementite, the cooling rate (time) when cooling the melt containing iron or iron alloy, iron or iron alloy material It depends on conditions such as the content of other atoms and carbon atoms present therein, and the thickness of the casting obtained by cooling the melt. By adjusting these conditions, carbon atoms can be contained in a desired form in the electrode material.

  The substrate formed using the electrode material may have a plate shape or the like, but preferably has a cup shape because the tube voltage and power consumption can be reduced. Those arranged opposite to each other in the vicinity of both ends inside the transparent tube are preferable. To create a cup-shaped electrode, the electrode material can be formed into a plate-shaped ingot, and a member cut out from this can be joined, and cut out into a circle, press-molded, and formed into a cup shape Those having a fine structure can be easily molded. The electrode material is formed into a strand, cut into a desired length, the cut surface is driven in the axial direction, a recess is formed, and a cup-shaped electrode is formed by a so-called header processing. Can be molded. The shape of the cup can be appropriately selected depending on the inner diameter of the transparent tube and the output of the lamp. For example, the outer diameter is 1.05 to 2.75 mm, the length is 3 to 8 mm, and the like.

  A rust preventive film is provided on the surface of the substrate. The rust preventive film contains one or more elements selected from nickel and chromium. Nickel and chromium are less susceptible to oxidation in the air, and when used on the electrode surface of the lamp, they are less susceptible to sputtering during lamp operation. For this reason, while suppressing generation | occurrence | production of rust in the iron or iron alloy base material which has a rust preventive film, generation | occurrence | production of the bad effect by sputtering can be suppressed. The rust preventive film is preferably provided on the entire surface of the electrode or the surface of the electrode other than the portion to which the lead wire is connected, that is, the surface of the electrode exposed to the air and subjected to oxidation. Even if the electrode portion to which the lead wire is connected is oxidized, it does not matter whether or not there is a rust-preventing film without being adsorbed by mercury when the electrode is mounted on the lamp.

  The thickness of the rust preventive film is preferably 0.05 μm to 2.3 μm. If the thickness of the rust preventive film is 0.05 μm or more, the generation of rust on the base material formed of iron or an iron alloy material can be suppressed, and if it is 2.3 μm or less, it is included in the rust preventive film. The amount of mercury consumed by these elements can be reduced.

  The above rust preventive film is formed by plating such as electroplating or electroless plating. If the shape of the electrode is, for example, a cup shape, a uniform film with few pores can be formed up to the surface inside the cup. This is preferable because it is possible. In the electroplating process, the plating metal used for the anode is preferably a high-purity metal. In the case of nickel, the plating bath is nickel sulfate, nickel chloride, a watt bath mainly composed of boric acid, nickel sulfamate. Further, a sulfamic acid bath mainly containing boric acid and containing nickel chloride or the like, a wood bath containing nickel chloride, a black nickel plating bath containing zinc ions together with nickel ions, or the like can be used.

  The electroless plating treatment is a treatment in which the cation of the plating metal contained in the plating bath is reduced with a reducing agent to deposit the metal on the object to be plated. As the reducing agent, for example, in the case of nickel, hypophosphorous acid is used. Acid, dimethylamine borane, hydrazine and the like can be used.

  The rust preventive film can also be formed by sputtering, vapor deposition, or metal spraying. The above sputtering is performed by setting a rust preventive film raw material as a target in a vacuum chamber, causing a rare gas or nitrogen ionized by applying a high voltage to collide with the target, and depositing sputtered metal atoms on a substrate. Get a rust-proof film.

The vapor deposition may be physical vapor deposition (PVD) or chemical vapor deposition (CVD). Physical vapor deposition is, for example, vaporized or sublimated by vapor deposition or sublimation by heating the vapor deposition metal with resistance heating, electron beam, high frequency induction, laser, etc. in a vacuum vessel of about 10 ⁻³ to 10 ⁻⁴ Pa, A rust preventive film can be formed.

  Chemical vapor deposition is preferred because it does not require a high degree of vacuum. As chemical vapor deposition, thermal CVD that forms a rust-preventive film by supplying a raw material gas and a reducing agent on a substrate installed in the apparatus and forms a rust prevention film by a thermal reaction, an organic metal vapor phase using an organic metal or gas as a raw material A growth method, other catalytic chemical vapor deposition methods, plasma CVD, epitaxial CVD, or the like can be used.

  In metal spraying, a film-forming material is heated and melted using a high-temperature combustion flame, plasma, or the like, and sprayed onto a substrate to form a rust-proof film. It is possible to use flame spraying such as hot wire type and powder type, electric spraying such as arc spraying and plasma spraying, high speed flame spraying, cold spray spraying and the like.

  A lead wire for connecting the electrode to an external power source is connected to the electrode. The lead wire can be provided with one end fused to the bottom surface of the electrode and the other end protruding through the sealing member for sealing the end of the transparent tube. As the lead wire, one having heat resistance is preferable in order to suppress deterioration when heated when fusing to the electrode and when the sealing member is closely attached to the transparent tube. In order to efficiently dissipate the heat of the electrode to the outside of the transparent tube, the lead wire in the lamp is a Kovar wire having a double structure in which a copper core wire is covered with Kovar, and the external lead wire is You may connect and use a jumet line etc.

  A sealing member such as a stem that seals both ends of the transparent tube holding the rare gas and mercury is provided through the lead wire and has a function of fixing the electrode via the lead wire. As the sealing member, for example, a glass bead, Kovar or the like is used.

  The cold cathode fluorescent lamp of the present invention suppresses the leakage of ultraviolet rays or the like emitted from mercury to the outside of the transparent tube between the phosphor layer and the transparent tube, or suppresses the deterioration of the transparent tube due to mercury or the like. Therefore, a protective layer may be provided. The protective layer can be formed using, for example, a metal oxide such as yttrium oxide or aluminum oxide.

  As a method of manufacturing the cold cathode fluorescent lamp, an ingot or a strand is prepared by using iron or an iron alloy and, if necessary, a melted material in which carbon, molybdenum, manganese, chromium, silicon or the like is melted. To form the above-mentioned cup shape or the like to mold the base material. A rust preventive film is formed on the surface of the base material by plating, sputtering, vapor deposition, metal spraying or the like to produce an electrode.

  Specifically, for example, when the iron atom content is 99.8% by mass and the carbon atom content is 0.11% by mass, the base material is melted at about 1500 ° C. Get. The obtained casting is plastically processed. In the plastic working, the coil material is formed using hot forging and hot rolling of the ingot. After pickling the obtained coil material, the strain is removed by annealing to improve the ductility, and the wire is drawn while adjusting the hardness. For example, the diameter is adjusted to 1 to 2.6 mm according to the electrode to be formed. It is formed into a wire with a diameter. Further, the wire rod is processed into a header and formed into a desired shape such as a cylindrical shape.

  Moreover, a plate material having a thickness corresponding to the electrode to be formed, such as a thickness of 0.1 to 0.2 mm, is formed by using hot forging, hot rolling, and cold rolling of the ingot. The obtained plate material may be formed into a desired shape such as a cylindrical shape by pressing, or may be cut and joined to a member to form an electrode. The heating temperature at the time of plastic working is preferably 350 ° C to 780 ° C.

  After the surface of the obtained electrode is polished, the lead wire is joined. In the case of a kovar wire, the electrode and the kovar can be directly integrated by resistance welding or laser welding.

  The phosphor layer on the inner wall of the transparent tube is prepared by preparing a dispersion liquid in which the phosphor is dispersed in a solvent, and immersing and spraying this on the inner wall surface of a transparent tube made of glass having a predetermined shape. The phosphor layer having the above thickness is formed by coating and drying by the above method. Then, an electrode can be arrange | positioned at the edge part of a transparent tube, a lead wire can be penetrated, and a transparent tube edge part can be sealed with a sealing member, and it can manufacture. Mercury and rare gas can be introduced into the transparent tube.

  As an example of the cold cathode fluorescent lamp of the present invention, the backlight for the liquid crystal panel shown in FIG. 1 can be exemplified. A cold cathode fluorescent lamp 1 shown in the schematic cross-sectional view of FIG. 1 is configured such that both ends of a glass tube 2 formed of borosilicate glass are hermetically sealed with glass beads 3 as sealing members. 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 phosphor layer 4 is provided on the inner wall surface of the glass tube 2 over almost the entire length thereof. A predetermined amount of rare gas and mercury are introduced into the internal space 5 of the glass tube 2 surrounded by the inner wall surface, and the internal pressure is reduced to about several tenths of the atmospheric pressure. As shown in the perspective view of FIG. 2, the glass tube 2 is protected on a cup-shaped substrate 7 a having an iron or iron alloy microstructure with an average crystal grain size of 4.9 μm or less, as shown in the perspective view of FIG. The electrode 7 having the rust film 7b is arranged so that the opening 10 faces. One end of the lead wire 9 such as a cover is welded to the bottom surface portion 8 of the cup-like electrode 7 and the other end is drawn out of the glass bead 3.

  Since the cold cathode fluorescent lamp uses an electrode having a rust preventive film on the surface, the oxidation of the base material of iron or iron alloy constituting the electrode can be suppressed, and the surface oxide film at the time of manufacturing the cold cathode fluorescent lamp Therefore, it can be manufactured efficiently. In particular, by providing an electrode having a fine structure of iron or iron alloy, it has excellent sputtering resistance, and a rust-proof film is uniformly formed on a fine-structured base material and is firmly bonded. Cold cathode fluorescent lamp with reduced impact on the environment, which suppresses contact with iron or iron alloy of the base material, suppresses the formation of amalgam, suppresses the amount of mercury introduced into the lamp from 2 to 5 mg from the conventional 4 to 5 mg Can be obtained.

Hereinafter, the present invention will be described in more detail by way of examples.
[Example 1]
A raw material in which graphite and other elements were added to iron in the ratio shown in Table 1 was melted at 1380 ° C. This melted material was poured into a mold having a cavity and quenched in water from 920 ° C. over 120 minutes. Then, hot rolling, cold rolling, drawing, etc. were repeated to produce a wire material having a diameter of about 0.2 mm. A cup-shaped electrode base material having an outer diameter of 1.7 mm and a length of 5 mm was produced by wire material header processing.

  On the obtained base material, nickel plating treatment was performed using a Watt bath to form a rust-proof film having a thickness of 0.1 μm to obtain an electrode.

The obtained electrode was left in the atmosphere (humidity 40 to 60%) for 72 hours, observed for the presence or absence of rust, and evaluated according to the following criteria. The results are shown in Table 1.
(Double-circle): Rust is not seen at all.
○: Rust is slightly seen.
Δ: Rust is slightly observed, but the effect of suppressing rust is recognized.
X: Rust occurs, and no rust suppressing effect is observed.

  Further, the obtained electrode was not left in the atmosphere, and a Kovar wire having a diameter of 0.8 mm was immediately integrated with the bottom by welding. About 18 μm of the phosphor was applied to the inner wall surface of a glass tube having a diameter of 2.0 mm. The electrodes in which the copal wires were fused to both ends of the glass tube were arranged so that the openings face each other, and both ends of the glass tube were sealed with glass beads penetrating the copal wires. Thereafter, mercury and a rare gas were introduced to produce a cold cathode fluorescent lamp.

Next, lighting was continued at a tube current of 12 mA to promote electrode wear. After the electrode wear has been sufficiently accelerated, the lamp ends are broken and inserted into a furnace heated to 800 ° C. to release non-amalgamated mercury from the tube, and the amount of remaining amalgamated mercury. Was measured. The effect of suppressing amalgamation was evaluated according to the following criteria. The results are shown in Table 1.
A: Very little mercury amalgamated.
○: Although partly amalgamated, the effect of suppressing amalgamation is sufficient.
(Triangle | delta): Although amalgamation is accelerated | stimulated, the amalgamation inhibitory effect is recognized.
X: Amalgamation is promoted and an amalgamation inhibitory effect is not recognized.
[Examples 2 to 26]
A cold cathode fluorescent lamp was produced in the same manner as in Example 1 except that the raw materials shown in Table 1 were used, and the amalgamation inhibitory effect was evaluated on the obtained cold cathode fluorescent lamp. The results are shown in Table 1.

[Comparative example]
A cold cathode fluorescent lamp was produced in the same manner as in Example 1 except that the raw materials shown in Table 1 were used, and the amalgamation inhibitory effect was evaluated on the obtained cold cathode fluorescent lamp. The results are shown in Table 1.

  It is clear that the cold cathode fluorescent lamp of the present invention has a great effect of suppressing amalgamation because the electrode is prevented from being rusted until the lamp is mounted.

It is a schematic block diagram which shows an example of the cold cathode fluorescent lamp of this invention. It is a perspective view which shows the electrode of an example of the cold cathode fluorescent lamp of this invention.

Explanation of symbols

1 Cold cathode fluorescent lamp 2 Glass tube (transparent tube)
3 Glass Bead 4 Phosphor Layer 5 Internal Space 7 Electrode 7a Base Material 7b Antirust Film 8 Bottom Surface 9 Lead Wire 10 Opening

Claims (10)

  A transparent layer provided with a phosphor layer on the inner wall, holding a rare gas and mercury inside, and sealed at both ends by a sealing member; electrodes provided near both ends of the inside of the transparent tube; In a cold cathode fluorescent lamp having a lead wire connected to the electrode and provided through the sealing member, the electrode has a base material formed of iron or an iron alloy material, and a rust preventive film on the surface of the base material. A cold cathode fluorescent lamp characterized in that the rust preventive film contains one or two elements selected from nickel and chromium.   2. The cold cathode fluorescent lamp according to claim 1, wherein the rust preventive film is provided on the entire surface of the electrode or the surface of the electrode other than the portion to which the lead wire is connected.   The cold cathode fluorescent lamp according to claim 1 or 2, wherein the rust preventive film is formed by plating.   4. The cold cathode fluorescent lamp according to claim 3, wherein the plating process is an electroplating process or an electroless plating process.   5. The cold cathode fluorescent lamp according to claim 3, wherein the thickness of the rust preventive film is 0.05 μm or more and 2.3 μm or less.   3. The cold cathode fluorescent lamp according to claim 1, wherein the rust preventive film is formed by sputtering, vapor deposition, or metal spraying.   The cold cathode fluorescent lamp according to claim 6, wherein the rust preventive film has a thickness of 0.05 µm or more and 2.3 µm or less.   The cold cathode fluorescent lamp according to any one of claims 1 to 7, wherein the content of carbon in the iron or iron alloy material is 0.5 mass% or less.   9. The cold cathode fluorescent lamp according to claim 8, wherein the iron or iron alloy material contains iron in a range of 99.5 mass% to 99.999 mass%.   The cold cathode fluorescent lamp according to any one of claims 1 to 9, wherein the iron or iron alloy material has a microstructure with an average crystal grain size of 4.9 µm or less.

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