JP2004199965A - Electrode member for discharge tube, and discharge tube and liquid crystal display using electrode member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode member for a discharge tube of low cost, long life and low power consumption and the discharge tube as well as a liquid crystal display using the electrode member. <P>SOLUTION: The electrode member for the discharge tube is formed by plastic working in machine work of a clad metal plate of a double-layer structure of a metal layer (B)1 made of a high-melting-point metal material and a metal layer (A)2 made of nickel or nickel alloy. Preferably, the electrode material for a fluorescent lamp has the high-melting-point metal layer (B)1 coated on the inside surface of a hollow-type electrode and the nickel metal layer (A)2 further inside. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a discharge tube electrode member serving as a discharge portion of an electrode in a discharge tube, a discharge tube using the same, and a liquid crystal display.
[0002]
[Prior art]
Conventionally, discharge tubes have been used for various applications in various fields. Recently, a cold cathode fluorescent lamp, which is one of the discharge tubes, is widely used as a backlight for a liquid crystal display of a notebook computer or the like.
[0003]
In a portable device such as a notebook personal computer, a power source for driving the portable device at the time of carrying depends on an internal battery. The backlight for the liquid crystal display is also turned on by battery operation. However, there is a limit to the power capacity of a battery. Therefore, it is important to reduce the power consumption of the cold cathode fluorescent lamp serving as the backlight.
[0004]
In order to reduce power loss and increase power consumption efficiency and reduce power consumption, it is necessary to minimize power loss during discharge, which is a major cause of power consumption of cold cathode fluorescent lamps. 2. Description of the Related Art Conventionally, (1) when a metal material having a small work function that easily emits electrons is applied to an electrode member (hereinafter, referred to as an electrode member) serving as a discharge portion of an electrode installed in a discharge tube, a cold cathode fluorescent lamp is used. Is known to be effective in reducing power consumption.
[0005]
In addition, when a cold cathode fluorescent lamp is used as a backlight for a liquid crystal display, the life of the user is shortened compared to the needs of the user because the user spends a long time in one day. Often easy. Therefore, extending the life of the fluorescent lamp is also a major issue.
[0006]
It is known that the life of a cold cathode fluorescent lamp greatly depends on the consumption rate of mercury vapor filled in a cold cathode tube (usually a glass tube is often used). A sealed gas of a rare gas such as argon or neon is sealed in the cold cathode tube separately from mercury. When a sufficient voltage is applied to the electrodes at both ends of the cold cathode fluorescent lamp, the charged gas of the cationized rare gas collides with the cathode electrode member to sputter the electrode member. Due to the sputtering, atoms of the electrode member fly out into the sealed gas to form mercury and amalgam. As a result, the mercury vapor in the cold-cathode tube is consumed, and the life of the fluorescent lamp may be reduced. Therefore, in order to prevent (2) consumption of mercury vapor as much as possible, it is necessary to use an electrode member having a low sputtering rate for the discharge portion of the electrode so that the electrode member is not sputtered as much as possible.
[0007]
In order to reduce the power consumption of the cold cathode fluorescent lamp by applying a metal material that easily emits electrons to the electrode member and has a low work function, and (2) to prevent consumption of mercury vapor, JP-A-2002-100319 and JP-A-2002-1110085 provide means for solving the problem of prolonging the life of a cold cathode fluorescent lamp using an electrode member having a low sputtering rate. In these publications, the work function is small, and it is described that a metal material selected from niobium, titanium, tantalum or an alloy thereof is selectively used as a material of the electrode member as an electrode member for reducing the sputtering rate. I have. As an effect, these metal materials have a higher melting point than conventional nickel-based metals or their alloys, have a low work function, reduce the sputtering rate of electrode members, and extend the life of fluorescent lamps. It is shown that it can be converted.
[0008]
Further, in Japanese Patent Application Laid-Open No. 2002-175776, the discharge portion is made of a metal material selected from niobium, titanium, tantalum, or an alloy thereof (hereinafter, a metal having a high melting point is referred to as a high melting point metal). To produce an electrode in which a concave portion is formed in the electrode member described in the above. This publication discloses that by forming a concave portion in an electrode member, it is possible to reduce power consumption, reduce heat generation, and extend the life, which can provide a hollow effect which is an advantage of a hollow electrode.
[0009]
[Patent Document 1]
JP 2002-175776 A [Patent Document 2]
Japanese Patent Application Laid-Open No. 2002-110085 [Patent Document 3]
Japanese Patent Application Laid-Open No. 2002-100319
[Problems to be solved by the invention]
However, the refractory metal material is considerably more expensive than conventionally used nickel and its alloy (hereinafter, referred to as nickel material), so that the electrode member using the refractory metal material is expensive. As an example, for example, molybdenum or niobium has been put to practical use in some fluorescent lamps as an electrode member made of a high-melting metal material, but the price is several times higher than that of a conventional nickel material electrode. .
[0011]
Further, an electrode member mainly using a high melting point metal material may be difficult as compared with conventional machining. For example, since a high melting point metal material has more robust material characteristics than a conventional nickel material, it is difficult to form a plate material as a discharge portion into an electrode member having a desired shape as a discharge portion. Therefore, the cost may increase from the viewpoint of difficulty in processing.
[0012]
The present invention has been made in view of the above problems, and provides a discharge tube electrode member that realizes low cost, long life, and low power consumption of a discharge tube, a discharge tube using the same, and a liquid crystal display. With the goal.
[0013]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, an electrode member for a discharge tube according to the present invention is an electrode member for a discharge tube, which is a discharge portion of an electrode installed in the discharge tube, wherein the electrode member has a metal layer on a surface of a metal layer (A). It is a coated metal electrode member having a portion coated with a high melting point metal layer (B) having a higher melting point than (A).
[0014]
By using the electrode member for a discharge tube of the present invention for a discharge tube, the metal layer (A) is coated with the high melting point metal layer (B). There are various advantages such as being able to be inexpensive.
[0015]
In addition, the high melting point metal layer (B) that at least partially covers the surface of the metal layer (A) has a low sputter rate and can prevent consumption of mercury and the like inside the discharge tube, and thus has a long life. There is no problem that it is a conversion.
[0016]
In addition, since the refractory metal layer (B) has a small work function, the cathode drop voltage at the time of discharge can be reduced. Therefore, there is no problem from the viewpoint that power consumption can be reduced.
[0017]
In order to form an electrode having such a configuration, for example, an electrode is formed from the metal layer (A), and then the surface of the metal layer (A) is coated with a high-melting point metal layer (B). Various methods are conceivable, such as a method of manufacturing an electrode member using a clad plate in which a high melting point metal layer (B) is clad on the surface of a metal layer (A) in advance.
[0018]
Here, the metal layer (A) of the electrode member for a discharge tube of the present invention may be a metal layer made of nickel or a nickel alloy.
[0019]
The high melting point metal layer (B) of the electrode member for a discharge tube according to the present invention is a metal layer made of at least one of molybdenum (Mo), tantalum (Ta), niobium (Nb), or an alloy thereof. It may be.
[0020]
The coated metal electrode member of the electrode member for a discharge tube of the present invention may be formed by processing a clad plate in which the metal layer (A) is clad with the refractory metal layer (B).
[0021]
As described above, by processing the electrode member from the clad plate in which the metal layer (A) is clad with the high melting point metal layer (B) in advance, the formation of the complicated electrode member can be prevented. Machining becomes easier than forming from a plate. Generally, when the melting point of the metal layer (A) is lower than that of the high melting point metal layer (B), plastic working is easy. Accordingly, this makes it possible to form a discharge tube electrode member having a complicated shape.
[0022]
The above-mentioned electrode member of the present invention is an electrode member having a hollow effect and having a hollow effect, wherein at least the inner surface of the concave portion is covered with the metal layer (B) on the surface of the metal layer (A). May be.
[0023]
With such a configuration, the refractory metal layer (B) can be coated on the inner surface of the concave portion of the electrode member where the hollow effect occurs further, and the same hollow effect as in the related art, lower power consumption and longer life can be achieved. In addition, combined characteristics of low heat generation and low power consumption and long life due to the high melting point metal layer (B) can be obtained.
[0024]
Further, the discharge tube of the present invention is characterized in that the discharge tube electrode member of the present invention is used as a discharge portion of an electrode.
[0025]
Further, the discharge tube of the present invention may be a fluorescent lamp for a backlight for a liquid crystal display.
[0026]
Further, a liquid crystal display of the present invention is characterized in that the above-described discharge tube of the present invention is used as a backlight.
[0027]
The present invention uses a discharge tube electrode member in which a metal layer (A) and a high-melting point metal metal layer (B) are combined as described above, so that the cost and long life of a discharge tube and a liquid crystal display using the same can be reduced. And various effects such as reduction in power consumption can be obtained.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiment of the present invention is a preferred example for carrying out the present invention, and the present invention is not limited to this embodiment.
[0029]
FIG. 1 is a structural diagram of a clad plate 10 which is a material of an electrode member of the present invention. The clad plate 10 can be manufactured by using a metal clad method described below. Each metal layer is adjusted in a cladding process so as to have a desired thickness. As a method for cladding the high melting point metal layer (B) 1 and the nickel material layer (A) 2, a rolling method and an explosion method are generally used. In the present embodiment, the rolling method is used to form the clad plate 10, but any method may be used as long as a method of forming a clad plate material is used. Since the advantages and the like are different for each method, an optimum method should be selected for manufacturing the clad plate. For example, the advantage of the rolling method is that it is suitable for forming a thin refractory metal layer (B) 1 because a clad plate having a required thickness and precision can be formed easily and with high precision. The refractory metal layer (B) 1 is clad on one side of a plate of the metal layer (A) 2 with a thickness of, for example, 5 μm to complete a clad plate 10 as a plate material of the present invention. Here, the clad plate 10 may have a metal layer structure in which the refractory metal layer (B) 1 is clad on both sides of the nickel metal layer (A) 2 if necessary, for example, for its use.
[0030]
FIG. 2 shows a hollow electrode 20 of the present invention formed using the clad material 10 of FIG. The hollow-type electrode includes an electrode member 20 a serving as a discharge part and a lead wire 4. Considering that the introduction wire 4 is fused to the glass tube in a later step, the glass beads 3 can be fused as shown in FIG. The hollow electrode member 20 has been often used in fluorescent lamps. The effect that the hollow effect can be obtained and the advantages such as the luminance similar to that of the hot cathode fluorescent lamp can be obtained is the same as the conventional effect.
[0031]
The clad plate 10 of FIG. 1 is machined into a hollow electrode member 20a of the present invention. In the present embodiment, the refractory metal layer (B) 1 is formed so as to be on the inner surface of the concave portion of the hollow electrode member 20a. The metal layer (A) 2 is made of nickel, which is a metal material that is easy to machine and is inexpensive compared to the high melting point metal layer (B) 1, but is actually iron (Fe), copper (Cu), Aluminum (Al) or an alloy thereof may be used, and an optimal metal layer (A) should be selected.
[0032]
In the case where the thickness of the electrode member 20a is the same as the conventional one, the clad plate 10 can reduce the thickness of the expensive refractory metal as the metal layer (A) 2 becomes thicker than the refractory metal layer (B) 1. Therefore, the overall material cost of the electrode member 20a is reduced, and the formation of the electrode member 20a having a concave portion from a plate material is easier than that of a high-melting-point metal electrode due to the characteristics of a metal such as nickel that is easily plastically worked. Due to this effect, it is possible to mass-produce the electrode members at low cost. In addition, it is possible to provide not only the concave shape of the hollow electrode member but also an electrode member having a more complicated electrode shape. For example, it is possible to form an electrode member having a complicated shape such as a shape having a plurality of concave portions or a tapered shape. Here, as a method of machining the clad material 10 into the electrode members, a method suitable for the present invention may be selected in consideration of a conventionally known method or the like.
[0033]
FIG. 3 shows a cold cathode fluorescent lamp 30 using the hollow cathode 20 as the electrode 20. This cold cathode fluorescent lamp 30 is a discharge lamp in which a pair of hollow cathodes 20 are arranged to face each other inside a glass tube 5 filled with a rare gas and mercury vapor, and a fluorescent film 6 is coated on the inner wall of the glass tube 5. The pair of hollow cathodes 20 and the glass tube 5, which are tubes, are fused by fusing the glass beads 3 previously fused to the introduction wire 4 with the glass tube 5. One end of an introduction wire 4 is connected to a pair of electrodes of the cold cathode fluorescent lamp, and the other end of the introduction wire 4 is led out from both ends of the glass tube. When a sufficient voltage is applied to the discharge between the pair of hollow cathodes 20 from outside via the introduction line 4, mainly the refractory metal layer (B) 1 which is the surface of the discharge portion 20 a of the hollow cathode 20 mainly emits electrons. Is released. The emitted electrons collide with mercury atoms existing in the glass tube 5 to excite hydrogen atoms and generate ultraviolet rays. The ultraviolet light collides with the fluorescent film 6 formed on the inner wall of the glass tube 5, is converted into a visible light wavelength, and the cold cathode fluorescent lamp 30 emits light.
[0034]
The configuration of the cold cathode fluorescent lamp 30 of the present embodiment will be described in more detail. The inner diameter of the glass tube 5 is 2.0 mm, the distance between the pair of hollow cathodes 20 is 50 mm, and Ar gas 10% -Ne is contained in the glass tube 1. A gas mixture of 90% gas has a gas pressure of 10 KPa and encapsulates 500 μg of mercury (Hg). Here, in the electrode member 20a of the hollow cathode 20 having a cylindrical shape, the outer diameter of the bottom surface circle of the cylindrical portion is 1.7 mmφ, and the length of the cylindrical portion in the cylindrical axis direction is 3.0 mm.
[0035]
In such a discharge tube, it is known that a discharge phenomenon easily occurs on the inner surface of the electrode member (discharge portion) 20a of the hollow cathode 20. Therefore, the electrode 20 of the present embodiment in which the refractory metal layer (B) 1 is coated on the inner surface portion of the concave portion which is directly involved in the discharge and the sputter rate is likely to be high, has the advantage of the refractory metal. A cold-cathode fluorescent lamp with a small sputter rate, a longer life by preventing the consumption of mercury in a fluorescent lamp, a lower work function, a lower voltage drop at the cathode, and a lower power consumption 30 can be provided. That is, the cold cathode fluorescent lamp 30 of the present embodiment using the hollow cathode 20 formed of the electrode member 20a is manufactured from the conventional electrode member made of only nickel or a high melting point metal material for the above-described reason. It is easy and can achieve low cost, long life, low power consumption, and the like. Therefore, in consideration of such effects and the like, the discharge tube of the present invention is suitable as a cold cathode fluorescent lamp used for, for example, a backlight for a liquid crystal display. As described above, there is a strong desire for a liquid crystal display to have a low price, a long life, and a low power consumption. The discharge tube of the present invention can provide a low cost, long life, low power consumption, and the like to the liquid crystal display. It can also be achieved by using.
[0036]
As a result of the inventor's intensive studies, in the present embodiment, if the refractory metal layer (B) 1 is at least 5 μm or more, there is no problem in obtaining the effects of reducing the sputtering rate and the power consumption. . However, if the refractory metal layer (B) 1 is too thick, the effects of reducing material costs and facilitating machining may be reduced. In other words, if the amount of expensive refractory metal is reduced in the entire electrode member, a rise in the material cost of the entire electrode member can be avoided. It is difficult to obtain the effect of reducing the amount. However, the thickness of the refractory metal layer (B) 1 depends on the usage of the electrode member 20 according to actual transactions and needs, the type of refractory metal, and the refractory metal layer (B) on both sides of the metal layer (A) 2. (1) Since the discharge characteristics may be different when, for example, 1 is coated, the thickness may be thinner than 5 μm or considerably thicker.
[0037]
The high melting point metal layer (B) 1 is preferably a niobium material having a small work function, and the metal layer (A) 2 is preferably nickel which is easy to machine, but is limited to those materials for the same reason. However, if the refractory metal layer (B) 1 is made of a material having a higher melting point than the metal layer (A) 2, the same effect as in the present embodiment can be obtained.
[0038]
Further, the discharge tube of the present invention may be other than the cold cathode fluorescent lamp. For example, the present invention can be widely applied not only to a discharge tube using a cold cathode, but also to a semi-hot type discharge tube other than the cold cathode.
[0039]
【Example】
(Examples and Comparative Examples)
A clad plate 10 was produced by using a molybdenum (Mo) material for the refractory metal layer (B) 1 and a rolling method for the nickel (Ni) metal layer (A) 2. The molybdenum layer is 5 μm, and the thickness of the clad plate 10 is 0.1 mm. Using this clad plate 10, a hollow electrode 20 having the shape shown in FIG. 2 was formed. The diameter of the bottom circle of the electrode member 20a in the hollow electrode 20 is 1.7 mmφ, and the height in the cylindrical axis direction is 3 mm.
[0040]
As described above, the cold cathode fluorescent lamp 30 illustrated in FIG. 3 was manufactured using the hollow-type electrode, and was used as an example of the present invention. In addition, as a comparative example, a cold cathode fluorescent lamp was manufactured using a conventional nickel electrode member not using the electrode member 20 of the present invention, and a cold cathode fluorescent lamp was manufactured by the same method and material except for the above. The cathode drop voltage, which is important as a characteristic representing the efficiency of the above, was measured by comparison. The cathode drop voltage was determined by changing the overall length of the fluorescent lamp, applying a DC voltage to the fluorescent lamp, and measuring the lamp voltage. As a result, the cathode lamp voltage of the fluorescent lamp of the present invention was 120 V, whereas the cathode drop voltage of the fluorescent lamp of the present invention was 110 V, which was about 9% smaller, so that the power consumption was reduced. Further, as for the life, it was confirmed that the example extended 1.5 times or more as compared with the comparative example, and it can be presumed that the life was prolonged by reducing the sputtering rate. Further, the clad material 10, which is a plate material of the electrode member 20a, uses only 5 μm of molybdenum. Since most of the material is nickel, molybdenum is also used for reducing material costs and facilitating machining. It could be improved over the electrode member. From the above, it is apparent that the product of the present invention exhibits excellent effects. Therefore, it can be applied to a fluorescent lamp for various uses, for example, a backlight for a liquid crystal display, etc., and is very useful industrially.
[0041]
【The invention's effect】
By using the electrode member of the present invention for a discharge tube, low cost, low power consumption, long life and the like of the discharge tube can be achieved. Therefore, if this discharge tube is used for a liquid crystal display, low cost, low power consumption, long life, and the like of the liquid crystal display can be achieved, which is industrially very useful.
[Brief description of the drawings]
FIG. 1 is a structural view of a clad plate as a material of an electrode member of the present invention.
FIG. 2 is a structural view of an electrode according to the present invention.
FIG. 3 is a structural diagram of a cold cathode fluorescent lamp according to the present invention.
[Explanation of symbols]
1 High melting point metal layer (B), 2 metal layer (A), 3 glass beads, 4 introduction line, 5 glass tube, 6 phosphor, 10 clad plate, 20 electrodes (hollow type cathode), 20a electrode member (discharge part) ), 30 cold cathode fluorescent lamp.

Claims (8)

In a discharge tube electrode member serving as a discharge portion of an electrode installed in the discharge tube,
The electrode member is a coated metal electrode member having a portion in which a surface of a metal layer (A) is coated with a high melting point metal layer (B) having a higher melting point than the metal layer (A);
An electrode member for a discharge tube. The metal layer (A) is a metal layer made of nickel or a nickel alloy;
The electrode member for a discharge tube according to claim 1, wherein: The refractory metal layer (B) is a metal layer made of at least one of molybdenum (Mo), tantalum (Ta), niobium (Nb), or an alloy thereof;
The electrode member for a discharge tube according to claim 1 or 2, wherein: The coated metal electrode member is formed by processing a clad plate in which the metal layer (A) is clad with the high melting point metal layer (B);
The electrode member for a discharge tube according to claim 1, wherein: The electrode member has a hollow portion and has a hollow effect, and at least the inner surface of the concave portion is covered with the high melting point metal layer (B) on the surface of the metal layer (A). The electrode member for a discharge tube according to any one of claims 1 to 4, wherein A discharge tube comprising a discharge tube electrode member using the discharge tube electrode member according to any one of claims 1 to 5. The discharge tube according to claim 6, wherein the discharge tube is a fluorescent lamp for a backlight for a liquid crystal display. A liquid crystal display using the discharge tube according to claim 6 as a backlight.

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