JPH11185699A - Cold cathode, and cold cathode fluorescent tube using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cold cathode of low discharge voltage capable of keeping stably a low voltage characteristic for a long time of 3000 hours or more, i.e., a cold cathode of high efficiency, having a long life, and excellent in workability. SOLUTION: This cathode is a cold cathode having a laminate structure comprising a conductive oxide 1a, and a metal 1b having a structure in which an interval between crystal faces is within the range of 0.201-0.21 nm, alternatively, a cold cathode having a laminate structure comprising a conductive oxide 1a and a metal 1b, and having a crystal face in which the conductive oxide 1a and the metal 1b are substantially matched. A cold cathode fluorescent tube using the cold cathode is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold cathode and a cold cathode fluorescent tube using the same, and more particularly to a cold cathode which is suitably used for a pack light for an LCD (liquid crystal display).

[0002]

2. Description of the Related Art Generally, fluorescent lamps are roughly classified into a hot cathode type and a cold cathode type.

[0003] Specifically, approximately 5φ
A hot cathode type having high luminous efficiency is used for those having a relatively large tube diameter, and an LCD backlight or the like can be easily miniaturized (narrowed), has a long life, generates relatively little heat,
The cold cathode type, which has advantages such as a simple lighting circuit, is widely used.

In this cold cathode fluorescent lamp, the filling gas is 1
More than one kind of rare gas is used, and in many cases,
g steam has been added. The gas pressure is 10 to 2
It is generally used in a range of conditions such as 6600 Pa and a discharge current of 1 to 20 mA.

A hot cathode type electrode is provided on the surface of a metal substrate.
BaO, SrO, CaO, or the like is applied as an emitter, thereby enabling low-voltage operation and realizing high luminous efficiency.

On the other hand, in the cold cathode fluorescent lamp, since there is no emitter that functions effectively in the cold cathode operation, the electrodes W, T
Transition metals such as a, Ni, Fe, and Zr, or alloys using these as main raw materials have been used.

Further, in order to realize an emitter which functions effectively in the cold cathode operation, an electrode of an oxide conductor having a perovskite type crystal structure such as (La, Sr) CoO ₃ has been developed. 190,137.

[0008] These stoichiometric perovskite oxide electrodes have a discharge current of 8 to 20 compared to W, Ni and the like.
The discharge voltage was as low as about 25 V in the mA range, and it was possible to lower the voltage and increase the efficiency of the cold cathode fluorescent lamp.

[0009]

However, such a perovskite-type oxide electrode tends to exhibit a low voltage effect only in a relatively large current range of 8 to 20 mA as a cold cathode, and at present, most 0.5-7.0m with many uses
In the range of A, the effect of the low voltage is small, and the voltage becomes equivalent to that of the conventional W electrode or the like.

[0010] In addition, the perovskite oxide electrode has a low voltage effect as an initial characteristic, but has a tendency that the effect is completely lost after lighting for only a few hours.

In order to use a perovskite-type oxide as an electrode, it is usually bonded to a metal in the form of a ceramic or a film. However, when the connection is made by mechanical connection under pressure or vapor deposition, the electrode is processed. At this time, the mechanical strength is insufficient, and if the electrode is to be miniaturized, it is destroyed.

Further, even when the film is made thin, the adhesive strength is not enough to withstand the electrode shaping, and the film is peeled off.

The object of the present invention was 0.5 to 7.0 m which could not be realized with a general perovskite oxide electrode.
In the current range of A, the discharge voltage is lower than that of the conventional W and Ni electrodes, and the low voltage characteristics are stably maintained for a long time of 3000 hours or more, that is, for a high efficiency and long life cold cathode fluorescent tube. It is an object of the present invention to provide a cold cathode which can be optimally used for the above-mentioned electrode and a cold cathode fluorescent tube using the same with a high yield.

[0014]

In order to achieve the above-mentioned object, the present invention provides a conductive oxide, wherein the distance between crystal planes is 0.2 mm.
A crystal having a laminated structure of a metal having a structure existing in the range of 01 to 0.21 nm or having a laminated structure of a conductive oxide and a metal, wherein the conductive oxide and the metal substantially match A cold cathode having a surface; and a cold cathode fluorescent tube using such a cold cathode.

With such a configuration, 0.5 to 7.0 m
In the current range of A, the discharge voltage is lower than that of the conventional W, Ni electrodes, etc., and the low voltage characteristics are stable for a long time of 3000 hours or more, that is, for a high efficiency and long life cold cathode fluorescent tube. The cold cathode which can be optimally used for the electrode and a cold cathode fluorescent tube using the same are provided with good yield.

Here, the conductive oxide is a conductive oxide containing at least one substance selected from lanthanoid elements, alkaline earth elements, and yttrium and at least one substance selected from transition metal elements. Is preferably usable.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention according to claim 1 has a laminated structure of a conductive oxide and a metal having a structure having a crystal plane spacing in the range of 0.201 to 0.21 nm. It is a cathode.

With such a configuration, 0.5 to 7 which cannot be realized with a general perovskite oxide electrode.
In the current range of 0 mA, the discharge voltage is lower than that of the conventional W, Ni electrodes, etc., and the low voltage characteristic is stably maintained for a long time of 3000 hours or more, that is, for a high efficiency and long life cold cathode fluorescent tube. The cold cathode which can be optimally used for the electrode is provided with a high yield.

According to a second aspect of the present invention, there is provided a cold cathode having a laminated structure of a conductive oxide and a metal, wherein the conductive oxide and the metal have a crystal plane substantially matching. is there.

Even with such a configuration, 0.5 to 0.5% cannot be realized with a general perovskite oxide electrode.
In the current range of 7.0 mA, the discharge voltage is lower than that of the conventional W and Ni electrodes and the low voltage characteristic is 300.
It is stable for a long time of 0 hours or more.
Provided is a high-yield cold cathode that can be optimally used as an electrode for a long-life cold cathode fluorescent tube.

According to a third aspect of the present invention, there is provided a laminated structure of a conductive oxide and a metal having a structure in which a distance between crystal planes is in a range of 0.201 to 0.21 nm,
The conductive oxide has a crystal plane spacing of 0.201 to 0.2.
A cold cathode having a crystal plane substantially matching the crystal plane of the metal existing at 21 nm.

[0022] Even with such a structure, 0.5 to 0.5 which cannot be realized with a general perovskite oxide electrode.
In the current range of 7.0 mA, the discharge voltage is lower than that of the conventional W and Ni electrodes and the low voltage characteristic is 300.
It is stable for a long time of 0 hours or more.
Provided is a high-yield cold cathode that can be optimally used as an electrode for a long-life cold cathode fluorescent tube.

Here, as the conductive oxide, A1, A2,... Are any of lanthanoid elements, yttrium, and alkaline earth elements;
... is any of transition metal elements, O is oxygen, α, β
... is a positive rational number, δ does not include 0, and +0.5 or less.
When formed into a 0.5 or more real, the formula (A1 _1- α _- β _{-
γ ··· A2αA3βA4γ ···) (B1 1-} ε - ζ - η ···
B2B3ζB4η...) It is preferable that the conductive oxide is represented by O ₃ -δ, and more specifically, the conductive oxide is LaCoO _3- δ or BaRuO _3-
δ, Pr _0.9 Ca _0.1 MnO ₃ -δ, Nd _0.6 Gd _0.2 Ca
_0.1 Sr _0.1 Co _0.7 Fe _0.3 O _3- δ or Gd _0.2 Ca
Preferably, it is _0.8 MnO _3- δ.

With such a conductive oxide, it is possible to surely realize a suitable laminated structure with a metal.

Here, a method for manufacturing such an oxygen-deficient or excess conductive oxide will be described.

First, the desired stoichiometric compound:
_{(A 1X- α - β ··· A2αA3β} ···) (B1 y- ε - ζ
_... B2εB3}... O _Z , where A: one or more lanthanoid elements, yttrium, alkaline earth elements, B: one or more transition metal elements, O: oxygen, x,
y, z: positive integers, α, β, γ: positive rational numbers) Mix the respective nitric acid solutions of the constituent elements in a desired element ratio,
This solution is dropped into a mixed solution of oxalic acid and ethanol to form a precipitate of these oxalates.

Next, the precipitate is dried at about 70 ° C., and the dried solid is mixed. The mixture is heated in air at about 500 ° C. for about 3 hours using an electric furnace to remove unnecessary oxalate. Decompose to form oxides of each constituent element.

Next, these oxides are finally calcined at 700 to 2000 ° C. for about 5 hours in an oxygen stream or air to obtain a composite oxide having a complete crystal structure. The main firing temperature differs depending on the compound and is appropriately selected.

If necessary, the powder after calcination is solidified by binding the particles, and is ground to several to several tens of microns using a mortar, a ball mill, or the like to obtain a desired particle size.

Further, a procedure for producing a conductive oxide deviated from the stoichiometry will be described. The amount of oxygen deficiency in the steady state of the stoichiometric oxide obtained as described above is uniquely determined by the oxygen partial pressure and the temperature except in the case of a reducing atmosphere.

Therefore, the desired oxygen-deficient oxide is
The stoichiometric oxide can be obtained by maintaining the stoichiometric oxide under a predetermined oxygen partial pressure and temperature environment until it reaches a steady state.

In the case of excess oxygen, firing may be performed in an oxidizing atmosphere. For example, depending on the setting of the oxygen partial pressure and the temperature when creating a laminate of a conductive oxide and a metal,
An excess oxygen type and an oxygen deficiency type may be selected.

If a desired conductive oxide can be obtained, it goes without saying that the manufacturing method is not limited to such a method.

On the other hand, as described in claim 6, the metal is:
It is preferred that nickel, iron, chromium, tin, silver, copper or gold be the main component.

With such a metal, it is possible to reliably realize a suitable laminated structure with the conductive oxide.

Here, as described in claim 7, the metal is:
A configuration in which the conductive oxide has a cylindrical shape, and the conductive oxide is provided in a layer shape on a side surface portion of the metal, or as described in claim 8, the metal has a columnar shape, and the conductive oxide is formed of the metal. The configuration provided in layers on the side surface and the tip portion is preferable because when applied to a cold cathode fluorescent tube, it has a simple configuration, high efficiency and long life.

Further, the present invention described in claim 9 is based on claim 1.
9. The cold cathode fluorescent tube having the cold cathode according to any one of items 1 to 8, wherein the cold cathode is a cold cathode fluorescent tube connected to the cold cathode fluorescent tube main body via the metal of the cold cathode.

With such a configuration, 0.5 to 7.0 m
In the current range of A, the discharge voltage is lower than that of the conventional W, Ni electrodes, and the like, and the low voltage characteristics are stable for a long time of 3000 hours or more. Is provided with good yield.

According to a tenth aspect of the present invention, there is provided a cold cathode fluorescent tube having the cold cathode according to the seventh aspect, wherein the cold cathode is disposed inside a metal cylindrical shape of the cold cathode. The cold cathode fluorescent tube is connected to the cold cathode fluorescent tube body by a member.

With such a configuration, 0.5 to 7.
In the current range of 0 mA, the discharge voltage is lower than that of the conventional W and Ni electrodes and the like, and the low voltage characteristics are stable for a long time of 3000 hours or more. Is provided with good yield.

The present invention according to claim 11 is a cold cathode fluorescent tube having a cold cathode according to claim 8, wherein the cold cathode is connected to the cold cathode fluorescent tube main body by the metal itself of the cold cathode. Cold cathode fluorescent tube.

With such a configuration, 0.5-7.
In the current range of 0 mA, the discharge voltage is lower than that of the conventional W and Ni electrodes and the like, and the low voltage characteristics are stable for a long time of 3000 hours or more. Is provided with good yield.

Here, as described in claim 12, it is preferable to have an electrode surface area such that the current density becomes 50 mA / cm ² or more and 5000 mA / cm ² or less.

That is, it is desirable to set the electrode surface area so that the discharge current density is in the range of 50 to 5000 mA / cm ² , which is different from conventional common sense. 50mA / cm
If it is set to ² or more, the low voltage characteristics in the low current region (0.5 to 7 mA) are further improved. However, if the current density is 5
Even if it is 0 mA / cm ² or less, a sufficient effect can be obtained. On the other hand, the upper limit is limited by the fact that when used at a current density higher than that, a sufficient life cannot be obtained due to the destruction of the electrode.

Hereinafter, a specific configuration will be described with reference to the drawings. (Embodiment 1) FIG. 1 (a) is a cross-sectional view of a cold cathode fluorescent tube according to the present embodiment, FIG. 1 (b) is an enlarged view of an electrode portion thereof, and FIG. It is a detailed enlarged view.

In FIG. 1, 1 is an electrode, 2 is a base for holding the electrode 1, 3 is a sealing glass member for sealing the electrode 1 together with the base 2, and 4 is an electrode together with the base 2 by the sealing glass member 3. Reference numeral 1 denotes a glass tube formed of a hard glass material to which is attached, reference numeral 5 denotes a phosphor disposed on the inner surface of the glass tube, and reference numeral 6 denotes a discharge gas filled inside the glass tube.

Here, first, the electrode 1 is made of a conductive oxide 1a.
And a metal 1b, and has a cylindrical shape as shown in the cross section. This electrode 1 may be applied to both opposing electrodes, or may be used for only one of them.

The base 2 is made of a Ni—Cr—Fe alloy, and is connected to the electrode 1.

The connection between the electrode 1 and the base 2 is performed by mechanical caulking, but can be realized by any of bonding with an Ag paste or the like and chemical bonding such as welding through W or the like. Or it may be via an intermediate layer material.

Next, one end of the glass tube 9 whose inner surface is coated with the phosphor 5 in advance and the base 2 are connected to the glass member 3 for sealing.
The other end is temporarily fixed at a position where a desired distance between the electrodes 1 is provided. That is, the position between the electrodes 1 does not move, but the gap between the other electrode 1 and the inner wall of the glass tube 4 is removed. The inside of the glass tube 9 is evacuated so that the gas can pass freely.

After the inside of the glass tube 9 is evacuated as described above, the discharge gas 9, that is, a gas containing one or more kinds of desired rare gas and, if necessary, a sufficient amount of Hg vapor, is cooled to a desired gas pressure. The glass tube 4 was completely sealed with the base 2 of the electrode 1 temporarily fixed and the glass tube 4, and then the chip was turned off to complete the fluorescent tube.

Specifically, the electrode 1 of the cold cathode fluorescent tube manufactured in the present embodiment has a columnar shape of about 0.6 φ × 4.0 mm, and is formed as a laminate of a conductive oxide and a metal by a sputtering method. The distance between the electrodes 1 is set to 80 mm, and a discharge gas 6 is filled with 10,000 Pa of Ne95% -Ar5% gas and a sufficient amount of Hg vapor.
0 mm. Needless to say, the stacked body of the conductive oxide and the metal can be formed by a general chemical vapor deposition method or physical vapor deposition method.

The electrode 1 of the present embodiment is configured as a laminate of the conductive oxide 1a and the metal 1b. As the conductive oxide 1a, La _1-X S
r _x (Co, Mn, Cr) O _3- δ, specifically, oxygen-deficient or excess La _1-x Sr _x CoO _3- δ, La _1-x Sr _x
MnO _3- δ and La _1-X Sr _x CrO _3- δ are converted to L
aCoO _3- δ, La _0.5 Sr _0.5 CoO _3- δ and SrCo
The method for producing such a conductive oxide using O _3- δ was in accordance with the method described above.

On the other hand, as the metal 1b, nickel, iron alloys (SUS601 and SUS304), chromium, tin,
Silver, copper, gold, platinum and tantalum were used.

In the step of making the conductive oxide 1a oxygen deficient or excessive, a conductive oxide having a stoichiometric composition laminated with the metal 1b is used while one electrode 1 is temporarily fixed. Then, the degree of vacuum, heating temperature, and evacuation time in the evacuation step were controlled.

Then, in this state, the adhesion state (strength) between the conductive oxide 1a and the metal 1b was confirmed. Specifically, in a state where the conductive oxide 1a and the metal 1b are laminated,
It was checked whether the metal and the conductive oxide did not peel off by being bent one inside and one outside.

The results are shown in Table 1 below.

[0058]

[Table 1]

According to Table 1, when nickel is used as the metal 1b, peeling may or may not occur. For SUS, gold, chromium, tin, silver, copper and gold, No delamination occurred, and in the case of platinum and tantalum, delamination occurred.

Here, the distance between the crystal planes of these metals is X
Examination of the diffraction pattern (2θ) in the case of using the source CuKα revealed that the metal having good adhesion without peeling had a crystal plane having a plane spacing in the range of 2.01 to 2.1 nm. In some cases, the metal which had peeled and had an inferior adhesion state had no crystal plane interval in the range of 2.01 to 2.1 nm.

That is, for SUS, gold, chromium, tin, silver, copper and gold, the spacing between crystal planes is 2.01 to 2.1 n.
m is included in the range, some of nickel is not, and some are not (nickel A is not included, and nickel B is included). In the case of platinum and tantalum, 2 is included. There are no crystal plane intervals included in the range of 0.01 to 2.1 nm, and these relationships are summarized in (Table 1).

Then, when the adhesion state was further confirmed using various metals, those having no crystal plane spacing included in the range of 2.01 to 2.1 nm, that is, having a plane spacing of less than 2.01 nm It was found that those having no more than 2.1 nm and those having more than 2.1 nm had peeling and poor adhesion.

Therefore, at least the physical conditions which the conductive oxide and the metal capable of realizing good adhesion to the conductive oxide satisfy are such that the crystal plane interval in the range of 2.01 to 2.1 nm exists. Is considered necessary.

Next, FIG. 2 to FIG. 7 show a state where the conductive oxide is laminated and the metal is nickel B, SUS601,
9 shows specific X-ray diffraction patterns for SUS304, gold and platinum.

According to FIGS. 2 to 6, nickel B, S having a crystal plane spacing in the range of 2.01 to 2.1 nm is used.
Regarding US601, SUS304 and gold, it was confirmed that a conductive oxide crystal plane matching the vicinity of a crystal plane having a plane spacing existing in a range of 2.01 to 2.1 nm of metal was present. According to the crystal plane spacing of 2.01 to
Regarding platinum not present in the range of 2.1 nm, no phenomenon was found in which the crystal plane of the conductive oxide matched the vicinity of the metal crystal plane.

Therefore, the physical conditions that the conductive oxide can achieve to achieve good adhesion are as follows:
It is considered necessary to have an orientation in which there is a crystal plane that is matched in the vicinity with a crystal plane included in the range of 1 to 2.1 nm.

As shown in FIG. 3, it was confirmed that when the laminate of the conductive oxide and the metal was subjected to the heat treatment in the oxidizing atmosphere, the diffraction spectrum appeared more clearly.

Then, the cold cathode fluorescent tube constructed as described above was turned on at 60 kHz using a high frequency inverter, and the discharge characteristics were evaluated.

FIG. 8 shows the relationship between the discharge current and the discharge voltage.
FIG. 8 shows LaCoO _3- δ, La _0.5 Sr _0.5 CoO
_3- δ and SrCoO _3- δ and nickel B shown in (Table 1)
And the W electrode for comparison.

FIG. 8 shows that LaCoO _3- δ and La _0.5
In the case of the electrodes using Sr _0.5 CoO _3- δ and SrCoO _3- δ, compared to the case of the W electrode, not only the current region of 7 mA or more but also the low current region of 0.5 to 7 mA is about 50%.
It shows a low V discharge characteristic at a low voltage.

Further, at a current of 4 mA, LaCoO _3- δ, La
As a result of comparing the efficiency of the electrode using _0.5 Sr _0.5 CoO _3- δ and SrCoO _3- δ with that of the W electrode, about 20%
Had improved.

FIG. 9 shows the relationship between the discharge current density and the discharge voltage at a discharge current of 3 mA. According to FIG. 9, in the case of the W electrode, when the current density is increased, the discharge voltage is increased, and there is no merit of setting the current density to 10 to 50 mA / cm ² or more.

However, LaCoO _3- δ, La _0.5 Sr _0.5
In the case of electrodes using CoO _3- δ and SrCoO _3- δ, 5
0~5000mA / cm also be used in the area of ² about a high current density discharge voltage is lowered, sufficient discharge voltage using a current density of 50 mA / cm ² or less can be understood to be low.

The above discharge characteristics are LaCoO _2.97 , Sr
When CoO _2.45 was also used, Mn was further added at the position of Co.
Can be obtained when Mn is replaced by Mn.
In this case, it was confirmed that the discharge was more stable than that of Co.

As the metal to be combined, in addition to nickel B, SUS601, SUS304, gold, silver,
Similar results were obtained with metallic materials including copper, tin and chromium.

In addition, when the heat treatment was performed in an oxidizing atmosphere when bonding with the metal, the low voltage maintenance life of the cold cathode fluorescent lamp tended to be improved. In this case, as described above, the X-ray diffraction spectrum of the conductive oxide appears more clearly, but it is considered that the amount of oxygen is also shifted from the stoichiometric composition ratio in the direction of increasing.

For example, in alloys (SUS304, SUS601) containing nickel metal or iron as a main component, the heat treatment improves the crystallinity of the conductive oxide, and discharges more stably.

Here, it is difficult to accurately determine the amount of oxygen deficiency or excess oxygen in the conductive oxide from the stoichiometric composition. However, when the state of the stacked body is chemically analyzed, the amount of oxygen is determined. Is preferably in the range of 3 ± 0.5, and it was also confirmed that the value deviated from the stoichiometric value. However, if the excess amount of oxygen exceeds 0.5, it tends to react with Hg gas in the discharge gas to shorten the life, and if the amount of deficiency exceeds 0.5, the composition becomes impossible as a compound, The range of excess and deficiency will be substantially defined for this reason.

Further, in this embodiment, the discharge voltage and the voltage life at a discharge current of 5 mA were measured using a laminate of various conductive oxides and metals. The results were summarized as A to G.

At the same time, the results when the corresponding stoichiometric oxides were used alone were shown as Comparative Examples A to G.

[0081]

[Table 2]

As can be understood from Table 2, when such a laminate of the conductive oxide and the metal is used for the electrode, the discharge voltage is sufficiently low and the life is long.

Further, a similar study was conducted using various conductive oxides. As a result, it was found that the following materials were suitable.

That is, LaCoO_3-δ, BaRuO_3-
δPr_0.9Ca_0.1MnO_3-δ, Nd _0.6Gd_0.2Ca_0.1
Sr_0.1Co_0.7Fe_0.3O_3-Chemical formula such as δ: (A1_1-α_-
β_-γ _...A2αA3βA4γ ...) (B1_1-ε_-ζ_-η
_...B2εB3ζB4η ...) O_3-What is represented by ι
Can be suitably used. Here, A1, A2, ...
Lanthanoid, yttrium, alkaline earth elements
.., B1, B2, etc. are the transition metal elements
O is oxygen, α, β ... are positive rational numbers,
The amount of elementary elements deviates from the stoichiometric value.

Then, for example, Y ₂ O ₃ , La ₂ O ₃ , Sr
O, NiO, A1, etc., represented by the chemical formula: A or AxOy (where A is any of lanthanoid elements, yttrium, alkaline earth elements, transition metal elements, O is oxygen, and x and y are positive integers) One or more of the objects may be included.

In the above measurements, five kinds of lamp inner diameters of 1, 2, 3, 4, and 5 mm, and a lamp length of 10,
5 types of 40, 80, 160, 320 mm, gas pressure of 10, 40, 60, 80, 100, 140, 180 to
7 types of rr, driving method is 100% H for various types of AC and gas including DC,
e, 100% Ne, 100% Ar, 100% Kr, 10
0% Xe, (1-x)% Ne-x% Ar, (1-x)%
Experiments were performed with various rare gases such as Ne-x% Xe and various conditions, and in each case, the effect of low voltage characteristics and long life was similarly confirmed.

As described above, according to the present embodiment, 0.5 to 7.0, which cannot be realized by the conventional oxide electrode, is used.
In the current range of mA, the discharge voltage is 40 to 60 V lower than that of the conventional W, Ni electrode and the like, and the low voltage characteristic is stably maintained for a long time of 3000 hours or more. A cold cathode fluorescent tube was realized.

(Embodiment 2) In this embodiment, a description will be given of an embodiment having the same configuration as that of Embodiment 1 except that the configuration of the electrodes is changed.

FIG. 10A is a cross-sectional view of the cold cathode fluorescent tube according to the present embodiment, and FIG. 10B is an enlarged view of the electrode portion.

In FIG. 10, reference numeral 10 denotes an electrode, and reference numeral 12 denotes a base for holding the electrode 10. Components similar to those in FIG. 1 are denoted by the same reference numerals.

The electrode 10 in the present embodiment is
A conductive oxide 10a was directly coated on the side surface and the tip of the columnar metal member also serving as No. 2 to form a laminate.

The coating on the metal surface serving as the electrode substrate can be formed by a sputtering method, a chemical vapor deposition method, or a physical vapor deposition method.

Of course, in order to increase the mechanical strength, a metal such as Ni may be welded to the base 12 as an electrode base having a desired shape.

Using the cold cathode fluorescent tube having the above structure, various conductive oxides and metals were combined in the same manner as in Embodiment 1, and the adhesion state, discharge voltage and life characteristics were evaluated. Obtained.

That is, even with the structure according to the present embodiment, 0.5 to 7.0, which cannot be realized by the conventional oxide electrode, is used.
In the current range of mA, the discharge voltage is 40 to 60 V lower than that of the conventional W, Ni electrode, and the like, and the low voltage characteristics are stably maintained for 3000 hours or more for a long time. It can be seen that a cathode fluorescent tube can be realized.

Of course, the shape of the cold cathode may be a column with a slightly rounded tip or a disk with little thickness.
Since it is a laminate of a conductive oxide and a metal having excellent shaping properties, any shape can be realized.

[0097]

According to the present invention, in the low current range of 0.5 to 7.0 mA, the discharge voltage is lower than that of the conventional W, Ni electrode and the like, and the low voltage characteristic is 3000 hours or more. It is possible to provide a cold cathode fluorescent tube that is stable for a long time, that is, has a small size, a high efficiency, and a long life, and can be widely applied to a wide range of devices such as an LCD backlight whose importance is rapidly expanding.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a cold cathode fluorescent tube according to a first embodiment of the present invention.

FIG. 2 is an X-ray diffraction image showing a crystal structure of a laminate of a conductive oxide and a metal of a cold cathode of the cold cathode fluorescent tube.

FIG. 3 is an X-ray diffraction image showing a crystal structure of a laminate of a conductive oxide and a metal of a cold cathode of the cold cathode fluorescent tube.

FIG. 4 is an X-ray diffraction image showing a crystal structure of a laminate of a conductive oxide and a metal of a cold cathode of the cold cathode fluorescent tube.

FIG. 5 is a view showing an X-ray diffraction image showing a crystal structure of a laminate of a conductive oxide and a metal of a cold cathode of the cold cathode fluorescent tube.

FIG. 6 is an X-ray diffraction image showing a crystal structure of a laminate of a conductive oxide and a metal of a cold cathode of the cold cathode fluorescent tube.

FIG. 7 is an X-ray diffraction image showing a crystal structure of a laminate of a conductive oxide and a metal of a cold cathode of the cold cathode fluorescent tube.

FIG. 8 is a diagram showing a relationship between a discharge current and a discharge voltage of a cold cathode of the cold cathode fluorescent tube.

FIG. 9 is a diagram showing a relationship between a discharge current density and a discharge voltage of the cold cathode fluorescent tube.

FIG. 10 is a sectional view of a cold cathode fluorescent tube according to a second embodiment of the present invention.

[Brief description of reference numerals]

 DESCRIPTION OF SYMBOLS 1 Electrode 1a Conductive oxide 1b Metal 2 Cap 3 Sealing glass material 4 Glass tube 5 Phosphor 6 Discharge gas 10 Electrode 10a Conductive oxide 12 Cap

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Hirofumi Yamashita 1-1, Yukicho, Takatsuki-shi, Osaka Matsushita Electronics Industrial Co., Ltd. (72) Toshihiro Terada 1-1-1, Yukicho, Takatsuki-shi, Osaka Matsushita Electronics Industrial Co., Ltd.

Claims (12)

[Claims] 1. The method according to claim 1, wherein the distance between the conductive oxide and the crystal plane is 0.2.
A cold cathode having a laminated structure with a metal having a structure existing in the range of 01 to 0.21 nm. 2. A cold cathode having a stacked structure of a conductive oxide and a metal, and having a crystal plane substantially matching the conductive oxide and the metal. 3. The distance between the conductive oxide and the crystal plane is 0.2.
The conductive oxide has a layered structure with a metal having a structure existing in the range of 01 to 0.21 nm, and the conductive oxide has a crystal plane spacing of 0.201 to 0.21 nm. A cold cathode having a substantially matched crystal face. 4. The conductive oxides A1, A2,... Are any of lanthanoid elements, yttrium, alkaline earth elements, B1, B2. O is oxygen, α, β... Are positive rational numbers, and δ is a real number not including +0 and not less than +0.5 and not less than −0.5 (A11 _- α _- β _- γ _...). A2αA3βA4γ ・
・ ・) (B1 _1- ε _- ζ _- η _... B2B3ζB4η ...)
4. The cold cathode according to claim 1, wherein the cold cathode is represented by O ₃ −δ. 5. The conductive oxide is LaCoO _3- δ, Ba.
_{RuO 3- δ, Pr 0.9 Ca 0.1} MnO 3- δ, Nd 0.6 Gd
_0.2 Ca _0.1 Sr _0.1 Co _0.7 Fe _0.3 O _3- δ or Gd
5. The cold cathode according to claim 4, wherein the cold cathode is _0.2 Ca _0.8 Mn03 _- δ. 6. The method according to claim 1, wherein the metal is nickel, iron, chromium, tin,
The cold cathode according to any one of claims 1 to 5, comprising silver, copper, or gold as a main component. 7. The metal according to claim 1, wherein the metal has a cylindrical shape, and the conductive oxide is provided in a layer on a side surface of the metal.
The cold cathode according to any one of the above. 8. The cold cathode according to claim 1, wherein the metal has a columnar shape, and the conductive oxide is provided in a layer on the side surface and the tip of the metal. 9. A cold cathode fluorescent tube having a cold cathode according to claim 1, wherein the cold cathode is connected to a cold cathode fluorescent tube main body via a metal of the cold cathode. Cathode fluorescent tube. 10. A cold cathode fluorescent tube having a cold cathode according to claim 7, wherein the cold cathode is connected to a cold cathode fluorescent tube main body by a connecting member disposed inside a metal cylindrical shape of the cold cathode. Cold cathode fluorescent tube. 11. A cold cathode fluorescent tube having a cold cathode according to claim 8, wherein the cold cathode is connected to the cold cathode fluorescent tube body by the metal itself of the cold cathode. 12. A current density of 50 mA / cm ² or more and 50 or more.
Cold cathode fluorescent tube according to any one of claims 9 to 11 having an electrode surface area such that 00mA / cm ² or less.