WO2011024235A1

WO2011024235A1 - Electrode

Info

Publication number: WO2011024235A1
Application number: PCT/JP2009/004233
Authority: WO
Inventors: 新田耕司; 稲沢信二; 徳田健之; 山▲崎▼和郎
Original assignee: 住友電気工業株式会社; 住電ファインコンダクタ株式会社
Priority date: 2009-08-28
Filing date: 2009-08-28
Publication date: 2011-03-03

Abstract

Disclosed is an electrode which can contribute to increase the luminance of a cold cathode fluorescent lamp. Specifically disclosed is a cup-shaped electrode used in a cold cathode fluorescent lamp, which comprises a base formed into a cup shape and a metal layer formed on the bottom portion of the inner surface of the base. The metal layer is formed by plating, and contains compound particles containing one or more metal elements selected from the group 1, group 2 and group 3 elements of the periodic table, and oxygen. Since the metal layer is formed by plating, adhesion between the metal layer and compound particles is excellent. Consequently, the electrode can hold compound particles having an excellent discharge performance for a long time, and thus can contribute to increase the luminance of a cold cathode fluorescent lamp.

Description

electrode

The present invention relates to an electrode used for a cold cathode fluorescent lamp. In particular, the present invention relates to an electrode from which a cold cathode fluorescent lamp having high brightness over a long period of time can be obtained.

Cold cathode fluorescent lamps are used as light sources for various electrical devices such as backlight light sources for liquid crystal display devices. This lamp typically includes a cylindrical glass tube having a phosphor layer on the inner wall surface and a pair of cup-shaped electrodes arranged at both ends of the tube, and a rare gas such as Ar and mercury in the tube. Is enclosed. The electrode is typically made of nickel, a lead wire is connected, and a voltage is applied to the electrode via the lead wire.

Recently, further enhancement of the brightness of the cold cathode fluorescent lamp is desired. In order to increase the brightness, it is effective to improve discharge characteristics (make it easier to emit electrons). In Patent Documents 1 to 3, an emitter made of a metal oxide such as barium (Ba) or cesium (Cs), which has a work function smaller than that of nickel and excellent in electron emission properties, is attached to the electrode or contained on the surface side of the electrode. The structure made is disclosed.

Japanese Unexamined Patent Publication No. 08-055603 JP 2002-175775 A JP 2005-183172 A

However, the conventional electrode has insufficient adhesion between the electrode and the emitter, and it is difficult to sufficiently contribute to the enhancement of the brightness of the cold cathode fluorescent lamp by dropping the emitter.

When a paste or aqueous solution is applied to the electrode and heat-treated as described in Patent Documents 1 and 2, the emitter is easily peeled off from the electrode (Patent Document 3 specification 0007), and the life of the lamp becomes extremely short. Not suitable for practical use. On the other hand, in the electrode described in Patent Document 3, the emitter powder and nickel powder are mixed and sintered, and then a plate obtained by rolling and a nickel plate are bonded together to form a clad material. Further, it is rolled into an electrode material (plate material), which is manufactured by subjecting this material to cup-like processing. In general, a sintered body has many defects such as pores. Therefore, when an electrode is shaved by the sputtering action of Ar ions, the emitter is easily dropped, and it is difficult to hold the emitter for a long time.

Therefore, an object of the present invention is to provide an electrode for a cold cathode fluorescent lamp that has high luminous efficiency and can maintain the effect over a long period of time.

Since the metal elements of Groups 1 to 3 of the periodic table generally have a low work function and good secondary electron emission properties, they are desirable for electrode materials (cathode materials) for cold cathode fluorescent lamps. However, since these metal elements are easily oxidized in the atmosphere, it is practically impossible to use a bulk material as an electrode as it is or to coat a conventional nickel electrode. On the other hand, although oxides of these metal elements exist stably in the atmosphere, they are inferior in workability, so that these oxides cannot be used for electrodes as they are. On the other hand, in the conventional configuration in which barium or cesium oxide powder is applied, the adhesion between the oxide and the electrode substrate is inferior. In contrast, the inventors of the present invention have a structure in which fine powder of a compound of a metal element of Groups 1 to 3 of the periodic table and oxygen is dispersed during plating, and the plating layer sufficiently retains the fine powder. Therefore, it has been found that a cold cathode fluorescent lamp having excellent luminous efficiency and capable of maintaining its effect for a long period of time can be obtained. The present invention is based on this finding, and a metal layer holding compound particles functioning as an emitter is formed by plating.

The electrode of the present invention is used for a cold cathode fluorescent lamp, and includes a base material formed in a cup shape and a metal layer formed on the bottom of the inner peripheral surface of the base material. This metal layer is formed by plating. In addition, this metal layer contains compound particles containing one or more metal elements selected from Group 1, Group 2 and Group 3 of the periodic table and oxygen.

The electrode of the present invention having the above-described configuration is such that the compound particles are sufficiently held in the metal layer, so that the discharge property is enhanced by the presence of the compound particles and the luminous efficiency can be improved. It is possible to contribute to high brightness over the range. Further, by forming the metal layer by plating, a metal layer in which compound particles are dispersed can be easily formed. Furthermore, the metal layer formed by plating is excellent in workability, and it is also possible to process the material on which the metal layer is formed (the material constituting the base material) into a cup shape. In addition, by forming the metal layer by plating, the metal layer can be formed on a plurality of base materials or materials at one time, so that the productivity of the electrode is excellent.

In the electrode of the present invention, the base material is preferably nickel or a nickel alloy. Nickel composed of Ni and impurities (so-called pure nickel) or a nickel alloy composed of additive elements and the balance Ni and impurities is excellent in plastic workability, and a cup-shaped electrode can be easily produced. Nickel and nickel alloys have a low melting point, and lead wires made of kovar or the like can be easily joined by welding.

Nickel alloys are disclosed in, for example, JP 2007-173197 A, specifically Ti, Hf, Zr, V, Fe, Nb, Mo, Mn, W, Sr, Ba, B, Th, Be. , Si, Al, Y, Mg, In, and one or more elements selected from rare earth elements (excluding Y) in total from 0.001% by mass to 5.0% by mass, with the balance being Ni and impurities preferable. This nickel alloy has a smaller work function than nickel, so it is easy to discharge, 2. It is difficult to sputter, 3. It is difficult to form an amalgam, 4. It is difficult to form an oxide film, so it is difficult to prevent discharge, etc. Has various advantages. The additive element typically forms an intermetallic compound with Ni and is present in the nickel base material.

In the electrode of the present invention, the metal layer is formed by plating. For plating, electroless plating or electroplating (electrolytic plating) can be used. The plating solution only needs to be liquid so that the raw material powder to be added (to be compound particles) does not dissolve, and can be appropriately selected according to the composition of the powder. For example, when the powder is soluble in an acid, the plating solution can be selected from an alkaline plating solution, an organic solvent, a molten salt, an ionic liquid, and the like. More specifically, for example, organic solvents are acetonitrile, dimethylformamide, etc., molten salt, such as LiCl-KCl, ionic liquids include those of various such EMI-BF ₄ and TMHA-TFSI. A plating solution other than those exemplified above may be used.

Note that the metal layer being formed by plating can be determined by examining the composition of impurities, the structure of the metal layer, the hardness of the metal layer, and the like. For example, when the metal layer is made of electrolytic nickel plating, the crystal grain size is small (average grain size: about 0.01 to 1 μm). Therefore, the size of the crystal grain is examined, and the additive used for forming the plating is further decomposed. Since elements (impurities) such as C and S to be mixed are mixed in the plating, the presence of these elements can be examined. Or, for example, when the metal layer is made of electroless nickel plating, elements (impurities) such as P and B derived from the reducing agent used for forming the plating are mixed in the plating, so the presence of these elements is investigated, Since this plating has a thermodynamically unstable amorphous phase, it is possible to examine the state of the structure.

The metal layer is provided at least at the bottom on the inner peripheral surface of the cup-shaped base material. The cup-like electrode can suppress the sputtering phenomenon to some extent due to the hollow cathode effect. As a result, it is possible to suppress a decrease in luminance due to mercury consumption accompanying this phenomenon. And, since the cup-shaped electrode discharges from the bottom and its vicinity in the inner peripheral surface, by providing a metal layer containing compound particles having excellent discharge performance at the bottom, Can be enhanced. On the inner peripheral surface, not only the bottom but also the region from the bottom to 1/3 of the length of the electrode is provided with the metal layer, so that the discharge performance can be further improved. A metal layer may be provided over the entire inner peripheral surface, or a metal layer may be provided on the outer peripheral surface of the cup-shaped electrode.

In the electrode of the present invention, the metal layer is preferably made of nickel or a nickel alloy.

Nickel and nickel alloy can be easily plated, and when the substrate is made of nickel or nickel alloy, the plating of nickel or nickel alloy and the substrate is excellent in adhesion. Furthermore, nickel plating or nickel alloy plating has little color unevenness, and a good appearance can be easily obtained, increasing the commercial value.

In the electrode of the present invention, the thickness of the metal layer is preferably 1 μm or more and 100 μm or less.

When the thickness of the metal layer is 1 μm or more, the compound particles can be easily retained, so that the time for sustaining the high brightness state can be extended. This effect is preferable as the thickness of the metal layer is thicker, but if it exceeds 100 μm, it is considered uneconomical because the lamp life is considered to be due to factors other than the disappearance of compound particles (for example, reduction of mercury). . A more preferable thickness is 10 μm or more and 50 μm or less. Although the thickness of a metal layer may differ partially, it is preferable that the metal layer provided in the bottom part of the internal peripheral surface of a base material satisfy | fills the said range. The thickness of the metal layer is measured as follows. The cross section of the electrode is observed with an optical microscope (500 to 1000 times), the thickness is measured over the entire area of the observed image, and the average value is taken as the thickness of the cross section. The thickness is measured for n = 5 cross sections, and the average of the five thicknesses is taken as the thickness of the metal layer.

In the metal layer, particles in a state where the entire peripheral surface of the compound particle is covered with the constituent metal of the metal layer (a state embedded in the metal layer) and at least a part of the outer peripheral surface of the particle are exposed. There are particles. In these compound particles, Ar ions enclosed in the glass tube collide with portions exposed from the metal layer, whereby secondary electrons are emitted. The compound particles embedded in the metal layer are exposed by scraping the metal layer near the particle by the sputtering action of Ar ions, and as described above, secondary electrons are generated by collision of Ar ions. It will be released. That is, the electrode of the present invention can maintain a high discharge performance because at least a part of the compound particles is automatically exposed from the metal layer when the cold cathode fluorescent lamp is turned on. In addition, you may perform the process for exposing a part of compound particle after forming a metal layer.

In the electrode of the present invention, the compound particles are preferably composed of at least one selected from alkali metal oxides, alkali metal salts, alkaline earth metal oxides, magnesium oxides and rare earth element oxides.

More specifically, alkali metal oxides: Li ₂ O, Na ₂ O, K ₂ O, Rb ₂ O, Cs ₂ O, alkali metal salts: Li ₂ TiO ₃ , Na ₂ Ti ₃ O ₇ , K ₂ TiO ₃ , Rb ₂ TiO ₃ , Cs ₂ TiO _{3 and} other alkaline earth metal and magnesium oxides: MgO, CaO, SrO, BaO, rare earth oxides: Sc ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , CeO ₂ , Pr ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ , Lu ₂ O ₃ may be used alone or in combination. These oxides and salts have a low work function and excellent discharge characteristics. In particular, among the alkali metal oxides, Rb ₂ O and Cs ₂ O having a large atomic radius are preferable because of their low work function. The composition of the compound particles and the base material in the metal layer can be measured by using, for example, SEM with EDX or X-ray diffraction.

In the electrode of the present invention, the compound particles preferably have a maximum diameter of 10 μm or less.

The emission efficiency of secondary electrons when viewed from the whole electrode tends to increase with the area where the compound particles are exposed from the metal layer. On the other hand, when the compound particles are present in the metal layer at the same volume ratio, the smaller the particles, the larger the surface area of the particles. Therefore, the area ratio of the particles exposed from the metal layer also increases and the electron emission efficiency improves. Moreover, when the compound particles are large, the particles easily fall off from the metal layer when the metal layer holding the particles is shaved due to the sputtering action of Ar ions. Accordingly, the compound particles are preferably smaller, and the maximum diameter is more preferably 1 μm or less, and no lower limit is particularly provided. A method for measuring the maximum diameter of the compound particles in the metal layer will be described later.

The particle size of the compound particles depends on the size of the raw material powder to be added when forming the metal layer, and the size of the raw material powder is almost maintained. Therefore, the raw material powder is preferably adjusted so that the particle size of the compound particles becomes a desired size. A commercially available powder having a desired size may be used, or a commercially available powder may be pulverized and a desired size may be selected with a sieve or the like.

Note that the shape of the compound particles is not particularly limited because it does not particularly affect the electron emission property. When pulverizing as described above, there may be various shapes such as a spherical shape (circular cross section), an elliptical cross section, a rectangular cross section, and a needle shape. Aspect ratio (minimum length (short side length, e.g. for elliptical particles: short diameter, rectangular particles: the largest of the perpendiculars to the maximum diagonal)) and maximum length (long side The ratio of the length of the compound particles per unit volume of the metal layer is such that the ratio of the length (for example, elliptical particles: major axis, rectangular particles: maximum diagonal) is relatively large). Since it becomes large, it is effective in suppressing the drop-off of the compound particles from the metal layer. Specifically, a shape satisfying an aspect ratio of 1: 2 to 1:50, typically a cross-sectional ellipse or a cross-sectional rectangle is preferable. When the aspect ratio exceeds 1:50, for example, when the length of the short side is 200 nm (0.2 μm), the length of the long side exceeds 10 μm, and as a result, the particle diameter increases. Since the shape of the compound particles depends on the shape of the raw material powder, the aspect ratio of the compound particles in the metal layer can be controlled by using, for example, a material powder from which particles having an excessive aspect ratio have been removed. The aspect ratio of the compound particles in the metal layer is determined by, for example, extracting the compound particles by image processing with an image analysis software obtained by observing the surface of the metal layer with an X-ray microscope, and extracting the maximum length of the extracted particles. And the minimum length is measured, and this measurement result is used.

In the electrode of the present invention, the content of the compound particles is preferably 1% by volume or more and 30% by volume or less.

When the metal layer is 100% by volume, the contribution of the compound particles to 1% by volume or more greatly contributes to the improvement of the luminous efficiency. It is possible to suppress a relative decrease in the amount of the constituent metal and maintain a high holding power, and to suppress instability of the light emission efficiency due to an increase in particle dropout. A more preferable content is 5% by volume or more and 15% by volume or less. A method for measuring the content of the compound particles in the metal layer will be described later.

The electrode of the present invention has a high luminance and can contribute to the realization of a cold cathode fluorescent lamp capable of maintaining a high luminance state over a long period of time.

Embodiments of the present invention will be described below.
<< Test Example 1 Presence or absence of metal layer >>
An electrode having a metal layer on a cup-shaped substrate was prepared, and a cold cathode fluorescent lamp using the electrode was further prepared to evaluate the performance of the lamp.

<Production of integral member>
An integrated member in which the base material and the inner lead wire are integrated is manufactured as follows. The ingot of nickel (LC-Ni (Ni201)) is hot-rolled, and the obtained rolled plate material is heat-treated and then surface-cut. The obtained surface-treated material is repeatedly subjected to cold rolling and heat treatment, and then subjected to final heat treatment (softening treatment) to produce a softened material having a thickness of 0.1 mm. The softened material is cut into a predetermined size, and the obtained plate-like material is cold-pressed to produce a cup-shaped base material (diameter φ 1.6 mm × length 3.0 mm). At the bottom of the outer peripheral surface of the obtained base material, a glass bead welded to an inner lead wire made of Kovar was welded and joined with a laser, and the inner lead wire with glass beads and the base material were integrated. An integral member is produced. In addition, after joining an inner lead wire to the bottom part of a base material, you may weld a glass bead.

A metal layer is formed on the base material of the obtained integral member as follows. Note that, when the metal layer is formed, when the base material needs to be conductive (Test Examples 4 and 5 to be described later), the inner lead wire is used to ensure the conduction.

<Formation of metal layer>
(Preparation of powder)
A powder made of a compound to be mixed with a plating solution (described later) is prepared. Here, commercially available Y ₂ O ₃ powder is pulverized with a ball mill, and is screened into the following four types according to particle size using a commercially available precision sieve. When the shape of the pulverized particles was examined, the aspect ratio generally satisfied 1: 2 to 1:50.
Powder type: 1-A>10μm> 50μm 1-B>5μm> 10μm 1-C>1μm> 5μm 1-D 1μm or less

(Metal layer formation process)
The metal layer is formed by a process of degreasing / hydrophilization treatment → catalyst application → catalyst activation → electroless plating. In the integrated member, portions other than the base material were previously masked using a commercially available PTFE masking tape.

[Degreasing and hydrophilization process]
The prepared integral member was immersed in Sulcup MTE-1-A (50 ml / L, 50 ° C., 1 L) manufactured by Uemura Kogyo Co., Ltd. for 5 minutes and then washed with water to degrease and hydrophilize the substrate surface.

[Catalyst application process]
Next, the integrated member after the above treatment was electroless nickel plating catalyst (mixed liquid 1L, 30 ° C of Sulcup PED-104 (270 g / L) and Sulcup AT-105 (30 ml / L) manufactured by Uemura Kogyo Co., Ltd.) ) For 2 minutes to give the substrate a catalyst.

[Catalyst activation process]
Subsequently, the substrate provided with the catalyst was immersed in Sulcup AL-106 (10% aqueous solution, 1 L, 25 ° C.) manufactured by Uemura Kogyo Co., Ltd. for 30 seconds to activate the catalyst.

[Electroless plating process]
A unit obtained by adding the prepared Y ₂ O ₃ powder at a rate of 10 g / L to Nibojoule U-77 (60 ° C, 1 L) manufactured by Uemura Kogyo Co., Ltd. The member was immersed for 6 hours (360 minutes) to form an electroless nickel plating layer having a thickness of 20 μm. By this step, an electrode member including an electrode having a metal layer (plating layer) formed on the entire inner and outer peripheral surfaces of the cup-shaped base material and an inner lead wire was obtained. Note that, after plating, the thickness of the metal layer was measured from an optical microscope observation image (1000 times) for five arbitrary cross sections of the electrode, and was equal to the formed thickness.

<Measurement of compound particles>
With respect to the obtained electrode member, the maximum diameter (μm) of the compound particles in the metal layer and the content (% by volume) of the compound particles were measured. The maximum diameter was determined as follows. The surface of the metal layer is observed with an X-ray microscope (field of view: 200 μm × 200 μm), an observation image (projection image) in which compound particles are dispersed is obtained, and this observation image is processed using commercially available image analysis software. To extract compound particles. The maximum length of each compound particle in the field of view is measured, the maximum value is taken as the maximum length of this field of view, and the average of five fields is shown in Table 1 as the maximum diameter. The content was determined as follows. The mass of the electrode and the mass of only the metal layer are measured, the electrode is dissolved with nitric acid or the like, and the constituent metal / compound particles of the substrate / metal layer are dissolved. The obtained solution is examined with an ICP emission spectroscopic analyzer, and the content of the compound is calculated from the concentration of the metal (Y in this case). And the mass of the constituent metal of the metal layer is determined from the difference between the mass of the metal layer and the calculated content of the compound. These calculation results and the density based on the composition analysis are used to convert to volume%. The results are shown in Table 1. The mass of only the metal layer is obtained by measuring the mass of the base material before plating and calculating the difference between the mass of the electrode and the mass of the base material. Alternatively, the mass of only the metal layer can be measured by removing the substrate portion from the electrode by polishing or the like. Polishing is easy if the electrode is cut or crushed and deformed before polishing.

<Production of lamp>
Further, a cold cathode fluorescent lamp was produced using the obtained electrode member, and the luminance was measured every 200 hours. The results are shown in Table 1. As a comparison, a cold cathode fluorescent lamp having an electrode having no metal layer was produced. In this comparative lamp (Sample No. 100), the integrated member before forming the metal layer was used as it is for the cold cathode fluorescent lamp.

The cold cathode fluorescent lamp was produced as follows. Prepare a pair of joining members that join the outer lead wires to the end of the inner lead provided in the electrode member, and have a phosphor layer (here, a halophosphate phosphor layer) on the inner wall surface and open at both ends One joining member is inserted into one end of the glass tube, and glass beads and one end of the glass tube are welded to seal one end of the glass tube, and the electrode of the joining member is fixed in the glass tube. Next, a vacuum is drawn from the other end of the glass tube to introduce a rare gas (Ar gas here) and mercury, and the other joining member is inserted to fix the electrode and seal the glass tube. By this procedure, a cold cathode fluorescent lamp in which the openings of a pair of cup-shaped electrodes are arranged to face each other is obtained.

<Ramp evaluation>
The brightness was evaluated by relatively expressing the brightness of the other samples, with the initial value (0 hr) of sample No. 100 having an electrode having no metal layer being 100. Five pairs of bonding members were prepared for each bonding member, and five lamps were produced. The luminance of each lamp was measured, and the luminance was evaluated using the average value of the five lamps as the value of each sample.

As shown in Table 1, Sample Nos. 1-1 to 1-4 having a metal layer containing compound particles have a high initial luminance and a small decrease in luminance after a long period of time. Can be maintained over a long period of time. In particular, it can be seen that the smaller the size of the compound particles, the higher the luminance.

<< Test Example 2 Metal Layer Thickness >>
With respect to Test Example 1, the immersion time of the plating solution was changed to produce an electrode in which the thickness of the metal layer was changed, and further, a cold cathode fluorescent lamp using this electrode was produced. Similarly, the lamp performance was evaluated. The results are shown in Table 2.

In this test, an electrode and a cold cathode fluorescent lamp were prepared in the same manner as in Test Example 1 except that the immersion time of the plating solution was changed (immersion time; sample No. 2-1: 3.6 minutes, sample No. 2-2: 36 minutes, sample No. 2-3: 1800 minutes). Note that, after plating, the thickness of the metal layer was measured from an optical microscope observation image (1000 times) for five arbitrary cross sections of the electrode, and was equal to the formed thickness. Further, for the obtained electrode (electrode member), the content (% by volume) of the compound particles was measured in the same manner as in Test Example 1. The results are also shown in Table 2.

As shown in Table 2, it can be seen that when the content of the compound particles is approximately equal, the thicker the metal layer, the smaller the decrease in luminance after a long time. The reason for this is considered to be that when the metal layer is thin, the metal layer is scraped by the sputtering action by Ar ions, and at the same time, the compound particles fall off and the base material is exposed. Sample No. 2-3 with a metal layer thickness exceeding 100 μm shows the same tendency as Sample No. 1-4 with a thickness of 100 μm or less. Therefore, it is sufficient that the thickness of the metal layer is 100 μm or less. Conceivable.

<< Test Example 3 Content of Compound Particles >>
Compared to Test Example 1, the amount of the raw material powder added to the plating solution was changed to produce an electrode having a metal layer with a different content of compound particles, and a cold cathode fluorescent lamp using this electrode The lamp performance was evaluated in the same manner as in Test Example 1. The results are shown in Table 3.

In this test, an electrode and a cold cathode fluorescent lamp were produced in the same manner as in Test Example 1 except that the amount of the raw material powder added to the plating solution was changed as shown in Table 3. Further, for the obtained electrode (electrode member), the content (volume%) of the compound particles was measured in the same manner as in Test Example 1. The results are also shown in Table 3.

As shown in Table 3, when the thickness of the metal layer is equal, it can be seen that the higher the content of the compound particles, the higher the initial luminance. However, Sample No. 3-3 with a large amount of compound particles has a relatively large decrease in luminance after a long time. The reason for this is considered to be that when the content is large, the amount of compound particles that drop off with time increases.

<< Test Example 4 Plating Method >>
Compared to Test Example 1, an electrode with a metal layer formed using a different plating solution was prepared, and further, a cold cathode fluorescent lamp was manufactured using this electrode, and the performance of the lamp was evaluated in the same manner as Test Example 1. did. The results are shown in Table 4.

In this test, an electrode and a cold cathode fluorescent lamp were produced in the same manner as in Test Example 1 except that the conditions of the plating process were changed. Further, for the obtained electrode (electrode member), the content (% by volume) of the compound particles was measured in the same manner as in Test Example 1. The results are also shown in Table 4.

[Plating process]
DMSO ₂ (dimethylsulfone): Temperature 120 ° C, 1 L, 100 g / L of anhydrous nickel chloride added, and 10 g / L of Y ₂ O ₃ powder of powder type 1-D prepared in Test Example 1 Was used as a plating solution. Here, the inner lead of the integral member that activated the catalyst is the negative electrode, the nickel plate (SK nickel manufactured by Sumitomo Metal Mining Co., Ltd.) is the positive electrode, and the current density is 5 A / dm ² for 20 minutes. A 20 μm nickel plating was formed. Moreover, this plating was performed in a glove box. Note that, after plating, the thickness of the metal layer was measured from an optical microscope observation image (1000 times) for five arbitrary cross sections of the electrode, and was equal to the formed thickness.

As shown in Table 4, regardless of the method of forming the metal layer (type of plating solution), by using an electrode comprising a metal layer containing compound particles, the initial luminance is high, and the luminance is high over a long period of time. It can be seen that a cold cathode fluorescent lamp capable of maintaining the state is obtained.

<< Test Example 5 Compound Particle Type >>
Compared to Test Example 4, an electrode having a metal layer formed using a raw material powder having a different composition was prepared, and a cold cathode fluorescent lamp using this electrode was prepared. Evaluated. The results are shown in Table 5.

In this test, the metal layer was formed by electroplating using an organic solvent in the same manner as in Test Example 4 (plating conditions are the same as in Test Example 4). Reagents (commercially available products) having the compositions shown in Table 5 were prepared as raw material powders to be added to the plating solution, and pulverized and screened with a ball mill in the same manner as in Test Example 1, and each powder was prepared with a particle size of 1 μm or less. Each of the prepared powders was mixed with the plating solution shown in Test Example 4 and electroplated, and a cold cathode fluorescent lamp was produced using the obtained electrode. Further, for the obtained electrode (electrode member), the content (% by volume) of the compound particles was measured in the same manner as in Test Example 1. The results are also shown in Table 5.

By using an electrode including a metal layer containing compound particles as shown in Table 5, it is possible to obtain a cold cathode fluorescent lamp having a high initial luminance and capable of maintaining a high luminance state over a long period of time. I understand.

It should be noted that the above-described embodiment can be appropriately changed without departing from the gist of the present invention, and is not limited to the above-described configuration. For example, you may form a base material and a metal layer with a nickel alloy. In addition, the compound particles may be configured to contain a combination of a plurality of different compositions. Further, a material in which a metal layer is formed may be prepared, and a cup-shaped process may be applied to the material to produce an electrode.

The electrode of the present invention can be suitably used for a cold cathode fluorescent lamp. The cold cathode fluorescent lamp is, for example, a backlight light source for a liquid crystal display device such as a liquid crystal monitor of a personal computer or a liquid crystal television, a light source for a front light of a small display, It can be suitably used as a light source for various electrical devices such as a light source for irradiating a document such as a copying machine or a scanner, or a light source for an eraser of a copying machine.

Claims

A cup-shaped electrode used in a cold cathode fluorescent lamp,
A base formed in a cup shape, and a metal layer formed by plating on the bottom of the inner peripheral surface of the base;
The electrode, wherein the metal layer contains compound particles containing one or more metal elements selected from Groups 1, 2, and 3 of the periodic table and oxygen.
2. The electrode according to claim 1, wherein the metal layer is made of nickel or a nickel alloy.
3. The electrode according to claim 1, wherein the compound particles have a maximum diameter of 10 μm or less.
The electrode according to any one of claims 1 to 3, wherein the content of the compound particles is 1% by volume or more and 30% by volume or less.
The electrode according to any one of claims 1 to 4, wherein the metal layer has a thickness of 1 µm or more and 100 µm or less.
2. The compound particles are made of at least one selected from an alkali metal oxide, an alkali metal salt, an alkaline earth metal oxide, a magnesium oxide, and a rare earth element oxide. 6. The electrode according to any one of 1 to 5.