JP3679397B2 - Electrode member for discharge tube, discharge tube using the same, and liquid crystal display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrode member for a discharge tube serving as a discharge portion of an electrode in the discharge tube, a discharge tube using the same, and a liquid crystal display.
[0002]
[Prior art]
Conventionally, discharge tubes have been used in various fields in various fields. Recently, a cold cathode fluorescent lamp, which is one of discharge tubes, has been widely used as a backlight for liquid crystal displays such as notebook personal computers.
[0003]
When a portable device such as a notebook computer is carried, the power source for driving the portable device depends on an internal battery. The backlight for the liquid crystal display is also turned on by battery driving. However, the power capacity of the battery is limited. Therefore, it is important to reduce the power consumption of the cold cathode fluorescent lamp as a backlight.
[0004]
In order to reduce the power loss to increase the power consumption efficiency and to reduce the power consumption, it is necessary to reduce the power loss at the time of discharge, which is a major cause of the power consumption of the cold cathode fluorescent lamp, as much as possible. 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 It is known to be effective as a reduction in power consumption.
[0005]
In addition, when a cold cathode fluorescent lamp is used as a backlight for a liquid crystal display, the user spends a long time for one day and the life is shortened in comparison with the user needs. 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, many glass tubes). In addition to mercury, a rare gas sealed gas such as argon or neon is sealed in the cold cathode tube. When a sufficient voltage is applied to the electrodes at both ends of the cold cathode fluorescent lamp, the cationized rare gas filled gas collides with the electrode member of the cathode and sputters the electrode member. By the sputtering, atoms of the electrode member jump out into the sealed gas to form mercury and amalgam. As a result, mercury vapor in the cold cathode tube may be consumed, resulting in the life of the fluorescent lamp. Therefore, in order to prevent (2) such consumption of mercury vapor as much as possible, it is necessary to use an electrode member having a low sputtering rate in the electrode discharge portion 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 mercury vapor consumption, Japanese Laid-Open Patent Publication Nos. 2002-100319 and 2002-110085 provide means for solving the problem of extending the life of a cold cathode fluorescent lamp using an electrode member having a low sputtering rate. These publications describe that a metal material selected from niobium, titanium, tantalum, or an alloy thereof is selectively used as an electrode member material as an electrode member that has a low work function and lowers the sputtering rate. Yes. As an effect, these metal materials are refractory metals compared to nickel-based metals or their alloys, which have been used in the past, have a low work function, and reduce the sputtering rate of electrode members, thereby extending the life of fluorescent lamps. It has been shown that
[0008]
Further, in Japanese Patent Application Laid-Open No. 2002-175776, the tip of the discharge part is made of a metal material selected from niobium, titanium, tantalum or alloys thereof (hereinafter, a metal having a high melting point is referred to as a high melting point metal). It is described that an electrode in which a recess is formed in an electrode member is prepared. In this publication, it is shown that by forming a recess in the electrode member, it is possible to achieve a reduction in power consumption, a reduction in heat generation, and a longer life, which can provide a hollow effect that is an advantage of the hollow electrode.
[0009]
[Patent Document 1]
JP 2002-175776 A [Patent Document 2]
JP 2002-110085 A [Patent Document 3]
Japanese Patent Laid-Open No. 2002-100319
[Problems to be solved by the invention]
However, since the refractory metal material is considerably more expensive than the conventionally used nickel and its alloys (hereinafter referred to as nickel material), the electrode member using the refractory metal material is expensive. As an example, for example, molybdenum or niobium or the like is used in some fluorescent lamps as an electrode member made of a refractory metal material. .
[0011]
In addition, an electrode member mainly using a refractory metal material may be difficult as compared with conventional machining. For example, since the refractory metal material has robust material characteristics as compared with the conventional nickel material, it is difficult to process and form the plate member as a material into an electrode member having a desired shape as a discharge part. 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 an electrode member for a discharge tube, a discharge tube using the same, and a liquid crystal display that realizes a low discharge tube, a long life, and low power consumption. With the goal.
[0013]
[Means for Solving the Problems]
In order to solve the above problems, an electrode member for a discharge tube according to the present invention is an electrode member for a discharge tube that serves as a discharge part of an electrode installed in the discharge tube. A coated metal electrode member having a portion coated with a refractory metal layer (B) having a melting point higher than that of (A).
[0014]
By using the electrode member for a discharge tube of the present invention as a discharge tube, the metal layer (A) is coated with the refractory metal layer (B), so that the electrode member mainly using the refractory metal layer (B) is used. There are various advantages such as low cost.
[0015]
Further, the refractory metal layer (B) that at least partially covers the surface of the metal layer (A) has a low sputtering rate and can prevent the consumption of mercury or the like inside the discharge tube, thus providing a long service life. There is no problem with being a computer.
[0016]
Further, since the refractory metal layer (B) has a small work function, the cathode fall voltage during discharge can be reduced. Therefore, there is no problem in terms of reducing power consumption.
[0017]
In order to obtain an electrode having such a configuration, for example, an electrode is formed with a metal layer (A), and then the surface of the metal layer (A) is covered with a film of a refractory metal layer (B), or the following Various methods such as a method of producing an electrode member using a clad plate obtained by previously clad a refractory metal layer (B) on the surface of the metal layer (A) can be considered.
[0018]
Here, the metal layer (A) of the electrode member for a discharge tube according to the present invention may be a metal layer made of nickel or a nickel alloy.
[0019]
The refractory 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 discharge tube electrode member 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 obtained by previously clad the refractory metal layer (B) on the metal layer (A), the formation of a complicated electrode member can be performed on the refractory metal layer (B). Machining and the like are easier than forming from a plate. Generally, when the metal layer (A) has a lower melting point than the refractory metal layer (B), plastic working is easy. Therefore, in this way, it is possible to form a discharge tube electrode member having a complicated shape.
[0022]
The electrode member of the present invention is an electrode member having a recess and having a hollow effect, wherein at least the inner surface of the recess is covered with the surface of the metal layer (A) by the metal layer (B). It may be.
[0023]
By adopting 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 further occurs, and the low power consumption and long life of the conventional hollow effect can be achieved. The combined characteristics of low heat generation, low power consumption and long life due to the high melting point metal layer (B) can be obtained.
[0024]
Moreover, 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 the electrode.
[0025]
The discharge tube of the present invention may be a fluorescent lamp for a backlight for a liquid crystal display.
[0026]
The liquid crystal display of the present invention is characterized by using the discharge tube of the present invention as a backlight.
[0027]
The present invention uses a discharge tube electrode member in which the metal layer (A) and the refractory metal layer (B) are combined as described above, thereby reducing the cost and long life of the discharge tube and the liquid crystal display using the discharge tube. Various effects such as reduction of power consumption and reduction of power consumption can be obtained.
[0028]
DETAILED DESCRIPTION OF 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 technique described below. Each metal layer is adjusted in the cladding process so as to have a desired thickness. As a method of cladding the refractory metal layer (B) 1 and the nickel material layer (A) 2, a rolling method or an explosion method is generally used. In this embodiment, the rolling method is used to form the clad plate 10, but any method may be used as long as it is a method for producing a clad plate material. Since the advantages and the like are different for each method, an optimum method should be selected for the production of 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 plate thickness and accuracy can be formed easily and with high accuracy. The refractory metal layer (B) 1 is clad on one side of the plate of the metal layer (A) 2 with a thickness of, for example, 5 μm to complete the clad plate 10 as the 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 surfaces of the nickel metal layer (A) 2 as required, such as for its use.
[0030]
FIG. 2 is a hollow electrode 20 of the present invention formed using the cladding material 10 of FIG. The hollow electrode includes an electrode member 20a that is a discharge portion and a lead-in wire 4. In consideration of the fact that the lead-in 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 conventionally used for fluorescent lamps. The effect that the hollow effect is obtained and the advantages such as the brightness approximate to that of the hot cathode fluorescent lamp can be obtained is the same as the conventional one.
[0031]
1 is machined into a hollow electrode member 20a of the present invention. In the present embodiment, the refractory metal layer (B) 1 is processed and formed so as to be 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 easier to machine and cheaper than the refractory metal layer (B) 1, but in reality, iron (Fe), copper (Cu), Aluminum (Al) or an alloy thereof may be used, and the optimum metal layer (A) should be selected.
[0032]
In the case where the thickness of the electrode member 20a is constant, 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 also reduced, and the formation of the electrode member 20a having a recess from the plate material is easier than a high melting point metal electrode due to the characteristics of a metal such as nickel that can be easily plastically processed. This effect enables mass production of electrode members at low cost. In addition, not only the concave shape of the hollow electrode member but also an electrode member having a more complicated electrode shape can be provided. 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 machining method from the clad material 10 to these 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 a hollow cathode 20 as the electrode 20. The cold cathode fluorescent lamp 30 is a discharge in which a pair of hollow cathodes 20 are arranged opposite to each other inside a glass tube 5 filled with a rare gas and mercury vapor, and the inner wall of the glass tube 5 is covered with a fluorescent film 6. 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 to the glass tube 5. One end of the introduction line 4 is connected to a pair of electrodes of the cold cathode fluorescent lamp, and the other end of the introduction line 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 the outside via the lead-in wire 4, electrons mainly from the refractory metal layer (B) 1 which is the surface of the discharge part 20 a of the hollow cathode 20. Is released. The emitted electrons collide with mercury atoms present in the glass tube 5 to excite hydrogen atoms and generate ultraviolet rays. This ultraviolet ray collides with the fluorescent film 6 formed on the inner wall of the glass tube 5 and is converted into visible light, and the cold cathode fluorescent lamp 30 emits light.
[0034]
The configuration of the cold cathode fluorescent lamp 30 of this 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 is 10% -Ne in the glass tube 1. A gas mixture of 90% gas has a gas pressure of 10 KPa and contains 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 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 is likely to occur on the inner surface of the electrode member (discharge part) 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 that is directly involved in the discharge and tends to increase the sputtering rate is advantageous in the refractory metal. A cold cathode fluorescent lamp with the advantage that it has a small sputtering rate, can extend the life by preventing mercury consumption in the fluorescent lamp, has a small work function, has a small voltage drop at the cathode, and can reduce power consumption. 30 can be provided. That is, the cold cathode fluorescent lamp 30 of the present embodiment using the hollow cathode 20 made of the electrode member 20a is manufactured from the conventional nickel member or the electrode member made of a refractory metal material for the above reason. It is easy and can achieve low cost, long life, low power consumption, and the like. Therefore, considering such effects and the like, the discharge tube of the present invention is suitable as a cold cathode fluorescent lamp used in a backlight for a liquid crystal display, for example. As described above, the liquid crystal display is desired to be low in price, long in life, and low in power consumption. The discharge tube of the present invention has low cost, long life, low power consumption, etc. in the liquid crystal display. It can also be achieved by using it.
[0036]
As a result of intensive studies by the inventor of the present application, 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 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. That is, if the amount of expensive refractory metal is reduced in the entire electrode member, an increase in the material cost of the entire electrode member can be avoided, but the reduction in the sputtering rate is a characteristic of the refractory metal material, so it has a longer life and power consumption. This makes it difficult to obtain the effect of reducing the above. However, the thickness of the refractory metal layer (B) 1 depends on the usage mode of the electrode member 20 according to actual transactions and needs, the type of the refractory metal, the both sides of the metal layer (A) 2 and the refractory metal layer (B). ) When 1 is coated, etc., the discharge characteristics may be different, so it may be thinner than 5 μm or considerably thicker.
[0037]
Further, the refractory metal layer (B) 1 is preferably a niobium material having a small work function, and the metal layer (A) 2 is preferably nickel that is easy to machine, but for the same reason, it is limited to these materials. If the refractory metal layer (B) 1 is a material having a higher melting point than that of the metal layer (A) 2, the same effects as those of the present embodiment can be obtained.
[0038]
Further, the discharge tube of the present invention may be other than a cold cathode fluorescent lamp. For example, the present invention can be widely applied to a discharge tube using a cold cathode as well as a semi-hot type discharge tube other than the cold cathode.
[0039]
【Example】
(Examples and Comparative Examples)
A molybdenum (Mo) material was used for the refractory metal layer (B) 1 and a clad plate 10 was formed on the nickel (Ni) metal layer (A) 2 by a rolling method. 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 produced using this hollow electrode, and this was used as an example of the present invention. Further, as a comparative example, a cold cathode fluorescent lamp is manufactured by the same method and material except that a conventional nickel electrode member that does not use the electrode member 20 of the present invention is used. The cathode fall voltage, which is important as a characteristic representing the efficiency of the above, was compared and measured. The cathode fall voltage was obtained 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, while the conventionally known fluorescent lamp was 120 V, the cathode fall voltage of the fluorescent lamp of the present invention was 110 V, which was about 9% smaller, so that the power consumption was reduced. In addition, regarding the life, it was confirmed that the example extended 1.5 times or more as compared with the comparative example, and it can be assumed that the life could be extended by reducing the sputtering rate. Further, the clad material 10 which is a plate material of the electrode member 20a only uses 5 μm of molybdenum, and most of the material is nickel. It was possible to improve compared to the electrode member. From the above, it is apparent that the product of the present invention has an excellent effect. Therefore, it can be applied to fluorescent lamps for various uses, such as backlights for liquid crystal displays, and is very useful in industry.
[0041]
【The invention's effect】
By using the electrode member of the present invention for a discharge tube, it is possible to achieve low cost, low power consumption, long life and the like of the discharge tube. Therefore, if this discharge tube is used for a liquid crystal display, the liquid crystal display can be manufactured at low cost, low power consumption, long life, and the like, which is very useful industrially.
[Brief description of the drawings]
FIG. 1 is a structural diagram of a clad plate which is a material of an electrode member of the present invention.
FIG. 2 is a structural diagram 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 refractory metal layer (B), 2 metal layer (A), 3 glass beads, 4 lead-in wire, 5 glass tube, 6 phosphor, 10 clad plate, 20 electrodes (hollow cathode), 20a electrode member (discharge part) 30) Cold cathode fluorescent lamp.

Claims (8)

In the electrode member for the discharge tube which becomes the discharge part of the electrode installed in the discharge tube,
The electrode member is an electrode member having a recess and having a hollow effect, wherein the surface of the metal layer (A) serving as the inner surface of the recess has a higher melting point than the metal layer (A). Coated with (B),
An electrode member for a discharge tube. In the electrode member for the discharge tube which becomes the discharge part of the electrode installed in the discharge tube,
The electrode member was formed by processing a clad plate clad with a refractory metal layer (B) having a melting point higher than that of the metal layer (A) on the surface of the metal layer (A),
An electrode member for a discharge tube. In the electrode member for the discharge tube which becomes the discharge part of the electrode installed in the discharge tube,
  The electrode member is an electrode member having a recess and having a hollow effect, wherein the surface of the metal layer (A) is clad with a refractory metal layer (B) having a higher melting point than the metal layer (A). Formed by processing a plate, the metal layer (A) becomes the inner surface of the recess, the surface is covered with the refractory metal layer (B),
  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 any one of claims 1 to 3, 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 any one of claims 1 to 3, wherein:   A discharge tube comprising a discharge tube electrode member according to any one of claims 1 to 5 as an electrode discharge portion.   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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