JP2008226764A - Cold cathode fluorescent lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cold cathode fluorescent lamp excelling in spatter resistance and having long life even when a high tube current is applied thereto, and easily and inexpensively manufacturable. <P>SOLUTION: This cold-cathode fluorescent lamp includes: a transparent tube having a phosphor layer formed on an inner wall surface, keeping an inert gas and mercury in the inside, and having both ends sealed by sealing members; electrodes formed in the vicinities of both ends in the transparent tube; and lead wires connected to the electrodes, and arranged by penetrating the sealing members. In the cold-cathode fluorescent lamp, the electrode contains nickel as a main constituent, and contains 0.4-6.5 mass% of tungsten. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cold cathode fluorescent lamp, and more particularly to a cold cathode fluorescent lamp that has a long life by improving the sputter resistance of an electrode.

  Cold cathode fluorescent lamps for backlights used in liquid crystal display devices such as televisions and computers, light sources for reading such as facsimiles, light sources for erasers of copiers, 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, and receiving the inner wall of the transparent tube Visible light is emitted from the phosphor provided in the.

  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. As the material of the electrode, the melting temperature is as low as about 1200 ° C., it is easy to process, it has excellent spatter resistance against mercury, rare gas ions, etc., and welding with Kovar or the like generally used for sealing members Nickel is used because it has good durability enough to withstand use at a tube current of 4 to 5 mA. However, the 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. High melting point sintered metals such as molybdenum and niobium, which are excellent in spatter resistance even under large loads, are used.

  For example, the electrode member is formed of a porous diffusion bonded body in which one or more kinds of metal particles selected from niobium, molybdenum, tantalum, and tungsten are bonded to each other by diffusion bonding, and the surface has a continuous unevenness of 0.1 to 5 μm. A cold cathode fluorescent lamp (Patent Document 1) is reported. In addition, a cold cathode tube electrode (Patent Document 2) is reported in which the electrode is made of a sintered body having an average particle size of 100 μm or less of a single metal such as tungsten, niobium, tantalum, molybdenum, rhenium, or an alloy thereof.

  However, on the other hand, deterioration of the lead wire that occurs when the lead wire is welded to such a high melting point sintered metal electrode and deterioration of the sealing member that occurs when both ends of the transparent tube are sealed become problems. ing. In addition, these electrode materials are expensive compared to nickel, and electrode forming is difficult, and consumables such as jigs are necessary, and the electrodes are extremely expensive. For this reason, the appearance of a nickel electrode excellent in sputter resistance is expected, and a nickel-molybdenum alloy electrode containing 6 to 35% molybdenum (Patent Document 3) has been reported. The sputtering resistance performance is drastically reduced at a high current exceeding 10 mA due to oxidation of the crystal grain boundary portion by a trace amount of oxygen in the lamp.

The present inventor has already developed an electrode in which nickel or a nickel alloy is used as a base material and yttrium is dispersed therein to improve the sputtering resistance. However, when a high current such that the tube current exceeds 10 mA is applied, heat generation of the electrode increases, and the sputtering resistance decreases.
JP 2006-156151 A JP 2004-178875 A JP 2006-12505 A

  The problem of the present invention is that it is resistant to oxidation of the surface portion when CCFL is mounted, and has excellent spatter resistance and long life even when a high tube current is applied, and it can be easily manufactured at low cost. It is to provide a cathode fluorescent lamp.

  As a result of diligent research, the present inventor has found that the electrode of the cold cathode fluorescent lamp contains nickel as a main component and contains tungsten at a predetermined content, or further contains molybdenum, so that a high current of 10 mA or more is obtained. It was found that even when applied, it has excellent sputtering resistance and can extend the life of the cold cathode fluorescent lamp. Based on this finding, the present invention has been completed.

  That is, the present invention is provided in the vicinity of both ends of a transparent tube having a phosphor layer on the inner wall, holding a rare gas and mercury therein, and sealed at both ends by a sealing member, and the inside of the transparent tube. And a lead wire connected to the electrode and penetrating the sealing member, the electrode contains nickel as a main component and tungsten is 0.4 mass% or more and 6.5 mass% or more. The present invention relates to a cold cathode fluorescent lamp characterized by containing in a range of mass% or less.

  The cold cathode fluorescent lamp of the present invention is resistant to oxidation of the surface portion when CCFL is mounted, and has excellent spatter resistance and long life even when a high tube current is applied, and can be easily manufactured at low cost. Can do.

  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 penetrating the sealing member, the electrode contains nickel as a main component, and tungsten is 0.4% by mass. It contains above 6.5 mass% or less, It is characterized by the above-mentioned.

  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 desired wavelength depending on the purpose of use, and examples thereof include halophosphate phosphors and rare earth phosphors. These can be used in appropriate combination to emit white light. The thickness of the phosphor layer is preferably 11 μm or more and 28 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 vapor pressure of mercury to be introduced can be 1 to 10 Pa, for example, when the fluorescent lamp is lit, and the rare gas pressure can be, for example, 5000 Pa to 11000 Pa, etc. when the fluorescent lamp is lit. be able to.

  The electrodes provided at both ends inside the transparent tube contain nickel as a main component, and contain tungsten in the range of 0.4 mass% to 6.5 mass%. Nickel as the main component may constitute all electrodes except for tungsten. The electrode containing nickel as a main component can suppress deterioration of the lead wire when connecting to the electrode, and deterioration of the sealing member when sealing the end of the transparent tube with the sealing member. Excellent formability.

  Tungsten contained in the electrode suppresses sputtering of the electrode due to collision of the ionized rare gas, and imparts excellent sputtering resistance to the electrode. Further, even if the crystal grain boundary portion is oxidized by residual oxygen when CCFL is mounted, the bonding strength of the crystal grain boundary is strong, and the sputtering resistance can be further improved. Content in the electrode of tungsten is 0.4 mass% or more and 6.5 mass% or less. If the content of tungsten is within this range, even when a current exceeding 10 mA is applied, the electrode has excellent spatter resistance against rare gas ionization bodies. Long life can be achieved.

  The electrode preferably contains molybdenum in the range of 3% by mass to 35% by mass. When molybdenum is contained in this range, an alloy of tungsten, molybdenum, and nickel is formed, so that the sputtering resistance is further improved. When the electrode contains molybdenum in such a content, even when a current exceeding 10 mA is applied, the electrode has even better spatter resistance and extends the life of the cold cathode fluorescent lamp. Can be planned.

  The electrode preferably contains yttrium in the range of 0.05% by mass to 1.10% by mass. When yttrium is contained in such a content, nickel crystal particles in the electrode can be formed as fine particles having an average particle diameter of, for example, 25 μm or less, and the particles are formed by the fine crystal particles. The bond between them becomes strong, and the sputtering resistance of the rare gas to the ionized body can be remarkably improved.

  Moreover, it is preferable that content of cobalt or iron in an electrode is 0.5 mass% or less, respectively. If the content of cobalt or iron is 0.5% by mass or less, these do not hinder the action of yttrium to refine the nickel crystal particles, and the nickel crystal particles in the electrode are formed as fine ones. The sputter resistance of the electrode can be further improved.

  Here, the average particle diameter of the crystal particles can be obtained from the particle diameter obtained by a comparison method using optical microscope observation of the electrode surface etched with acid. Specifically, in accordance with the method described in “The Introductory Metal Material and Structure” (P189-193), edited by Japan Heat Treatment Technology Association, published by Okawa Publishing Co., Ltd. In an 8 mm circle and a circle with a photographic print size diameter of 80 mm, the corresponding particle size number is determined in comparison with a standard drawing to obtain an average particle size. For example, since the particle diameter of 25 μm is located at 7.5, which is exactly the middle between the particle size numbers 7 and 8, an average value of the particle diameter can be obtained.

  It is preferable that the electrode has a cup shape because the tube voltage and power consumption can be reduced, and the cup-shaped openings are arranged opposite to each other in the vicinity of both ends of the transparent tube. Those are preferred. A cup-shaped electrode can be made by joining members cut out from a plate-shaped ingot, but it can be easily cut into a circle, press-molded, and formed into a cup-like shape. Can be molded. Further, the cup-shaped electrode can be easily formed by cutting the strand into a desired length, driving the cut surface in the axial direction, forming a recess, and forming a cup shape, so-called header processing. 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 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. The lead wire preferably has heat resistance in order to suppress deterioration due to heating when the sealing member is in close contact with the transparent tube, and the heat of the electrode during use of the lamp is transferred to the outside of the transparent tube. A Kovar wire having a double structure in which a copper core wire is covered with Kovar so that heat can be efficiently radiated can be used.

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

  The cold cathode fluorescent lamp of the present invention suppresses leakage of ultraviolet rays, etc. emitted from mercury to the outside of the transparent tube between the phosphor layer and the transparent tube, or suppresses 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, aluminum oxide, or cerium oxide.

  As a method of manufacturing the cold cathode fluorescent lamp, an ingot or strand made of these alloys is prepared by mixing yttrium with a melt of nickel and tungsten or nickel, molybdenum and tungsten, and a fine crystal is formed using this. An electrode having particles is formed.

  As a method for producing the electrode, specifically, a metal mainly composed of nickel constituting the electrode is melted. As the melting temperature, melting near the melting point of nickel is preferable because an electrode of fine crystal particles can be obtained.

  Thereafter, this melt is poured into an ingot mold to form a nickel alloy ingot containing these metals. Further, the ingot can be plastically processed by hot rolling or cold rolling to form a thin plate having a thickness of 0.1 to 0.2 mm or a strand having a diameter of 1 to 2.6 mm. After hot rolling or cold rolling, the ingot is annealed, the internal strain is removed, the ductility is improved, and the surface is polished. An electrode having a fine crystal structure can be obtained by press molding or header processing of the strand. A lead wire is fused and connected to the obtained electrode.

  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 noble gases 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. The 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 bead glass 3. 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 (not shown) is provided on the inner wall surface 4 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 4, and the internal pressure is reduced to about several tenths of the atmospheric pressure. As shown in the enlarged perspective view of FIG. 2, cup-shaped electrodes 7 containing the above components are disposed at both ends in the longitudinal direction of the glass tube 2 so that the openings 10 face each other. One end of each lead wire 9 is welded to the bottom surface portion 8 of the electrode 7, and the other end passes through the bead glass 3 and is drawn out of the glass tube 2.

  The cold cathode fluorescent lamp has nickel as a main component, contains a predetermined amount of tungsten, contains a predetermined amount of molybdenum and yttrium as necessary, and has an electrode with a fine crystal structure, and therefore has a sputtering resistance against a rare gas. This is a significant improvement and extends the life of the cold cathode fluorescent lamp.

Hereinafter, the present invention will be described in more detail by way of examples.
[Example 1]
Starting material having a composition of 0.3% by mass as a total of 71.4% by mass of nickel, 3.3% by mass of tungsten, 25.0% by mass of molybdenum, and other impurities such as carbon, silicon, copper, sulfur, magnesium, etc. It melted at a temperature above its melting point. This melt was poured into a mold and cooled to room temperature, and then hot rolling and cold rolling were repeated to produce a roll material having a thickness of about 0.2 mm. The roll material was annealed, and after surface polishing, the roll material was press-molded to produce a cup-shaped electrode having an outer diameter of 1.7 mm and a length of 5 mm. A Kovar wire having a diameter of 0.8 mm was integrated with the bottom surface of the obtained electrode by welding.

  The average crystal particle diameter of nickel of the electrode was measured by a comparative method. The nickel average crystal particle diameter was 20 μm.

  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.

The obtained cold cathode fluorescent lamp was lit at a tube current of 10 mA, and then the spatter resistance was observed by the amount of wear of the cup portion. Sputter resistance was evaluated according to the following criteria from the amount of wear of the electrode cup. The results are shown in Table 1.
(Double-circle): Wear of a cup part is seen very little.
○: Wear of the cup part is recognized, but it can be used sufficiently.
Δ: Wear of the cup portion is observed, but it is a limit area for use.
X: The cup portion is so worn that it cannot be used.
[Examples 2 to 4]
A cold cathode fluorescent lamp was produced in the same manner as in Example 1 except that the starting material was changed to the composition shown in Table 1, and the resulting cold cathode fluorescent lamp was evaluated for sputtering resistance. 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 starting material was changed to the composition shown in Table 1, and the resulting cold cathode fluorescent lamp was evaluated for sputtering resistance. The results are shown in Table 1.

  It is clear that the electrode in the present invention is excellent in sputtering resistance, and the cold cathode fluorescent lamp of the present invention is excellent in durability.

It is a figure which shows the schematic sectional drawing of an example of the cold cathode fluorescent lamp of this invention. It is a figure which shows the schematic perspective view of an example of the electrode shown in FIG.

Explanation of symbols

1 Cold cathode fluorescent lamp 2 Glass tube (transparent tube)
3 Bead glass 4 Inner wall surface 5 Internal space 7 Electrode 8 Bottom surface portion 9 Lead wire 10 Opening portion

Claims (3)

  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 the cold cathode fluorescent lamp having a lead wire connected to the electrode and provided through the sealing member, the electrode contains nickel as a main component, and tungsten is in a range of 0.4 mass% to 6.5 mass%. A cold cathode fluorescent lamp comprising:   The cold cathode fluorescent lamp according to claim 1, wherein the electrode contains molybdenum in a range of 3 mass% to 35 mass%.   3. The electrode according to claim 1, wherein the electrode contains yttrium in a range of 0.05% by mass to 1.10% by mass, and the content of cobalt or iron is 0.5% by mass or less, respectively. Cold cathode fluorescent lamp.

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