JPH02215039A - Discharge electrode - Google Patents

Abstract

PURPOSE:To improve the emission and the thermal shock resistance and enlarge the current density by bonding a sputtering preventing layer to the surface of a cylindrical semiconductive ceramic, and comprising a surface without a bond of the sputtering preventing layer in a back surface of the flying direction of Hg and rare gas ion. CONSTITUTION:A discharge electrode 10 has a cylindrical ceramic base material 12, a sputtering preventing layer 16 to be bonded to the surface thereof and a non-through hole part 14 provided in one surface of the cylinder. The sputtering preventing layer 16 is not provided inside of the hole part 14. It is desirable that narrow and long channels 16a, 16b to be engaged with a conductive lead 20 are provided in the side surface of the cylinder in the axial direction of the cylinder so as to be held with the conductive lead 20. Thereby, an electrode having the fine emission, the low lamp voltage, the low restriking voltage of arc and the strong thermal shock resistance without the damage by ion sputtering can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a discharge electrode, and particularly to the structure of the electrode.

(Prior Art) Conventionally, metals such as nickel have been used as electrode materials for discharge lamps such as fluorescent lamps, especially those called cold cathode discharge lamps. However, this case has disadvantages such as low emissions (high tube voltage, high restriking voltage).

On the other hand, ceramic discharge electrodes have been proposed in which ceramics such as BaTiOs are converted into semiconductors by reduction treatment (for example, USP 2686274), but conventional ones are weak against thermal shock and are made by ion sputtering using mercury particles and rare gas ions. It has drawbacks such as easy deterioration and low current density.

(Problems to be Solved by the Invention) Therefore, the present invention improves the above-mentioned drawbacks of the conventional technology, does not require preheating, has good emission, has low tube voltage and restriking voltage, is resistant to thermal shock, and has high current The purpose is to provide a discharge electrode with high density.

(Means for Solving the Problems) The features of the present invention for achieving the above-mentioned objects include a semiconducting ceramic having a semiconducting shape, a sputtering prevention layer attached to the surface of the ceramic, Hg, Ar,
The discharge electrode has a surface on which the sputtering prevention layer is not attached on the back surface in the direction in which rare gas ions such as Ne, Xe, Kr, etc. fly, and a lead wire bonded to the ceramic.

(Operation) Electrons are abundantly emitted from the electrode from the surface to which the sputtering prevention layer is not attached.

On the other hand, this surface is composed of Hg, Ar, Ne, Xe, K
It is susceptible to ion bombardment of rare gas ions such as By providing a sputtering prevention layer on the surface, a discharge electrode with excellent electron emission characteristics and resistance to ion bombardment can be obtained.

(Example) FIG. 1 shows the structure of a discharge electrode according to the present invention, in which a conductor lead (for example, tungsten, molybdenum, nickel). 13 is an insulating material such as ceramics coating the outer periphery of the conductor lead. This prevents the conductor metal from sputtering due to ion bombardment such as Hg ions, which may cause electrons to be emitted from the conductor leads during discharge. The discharge electrode IO has a ceramic matrix 12 having a hollow cylindrical shape, a sputtering prevention layer 16 attached to the surface thereof, and a non-penetrating hole 14 formed on one surface of the cylinder. It is assumed that the sputtering prevention layer 16 is not provided inside the hole 14 . Preferably, in order to hold the conductor by the conductor lead 20, the elongated groove 1 is connected to the conductor lead 20.
6a and 16b are provided on the side of the cylinder in the axial direction of the cylinder (Fig. 2).

In the above structure, the ceramic matrix 12 is a ceramic made into a semiconductor by reduction treatment, such as BaTiO
It is s.

The Suba☆tan rig prevention layer 16 may be coated on the surface of the completed ceramic matrix by vacuum deposition or the like, but it is preferably a surface precipitated layer formed on the surface during reduction treatment.
Although its own emission effect is small, it is resistant to sputtering of mercury ions.

The ceramic matrix 12 is exposed in the hole 14, and electrons are emitted from this portion.

As shown in FIG. 1, the electrode is coated with a sputtering prevention layer 16.
is facing the ion flying direction (the direction of the counter electrode), and the hole 1
4 is arranged so as to face the opposite side to the direction in which the ions fly.

In the illustrated structure, the ceramic matrix 12 has excellent emission (electron emission) characteristics and emits abundant electrons from the holes 14, which move along arrow A and contribute to the discharge of the discharge lamp according to known theory. . On the other hand, gas ions (for example, Hg ions) generated due to the discharge fly to the electrode from the direction of the arrow in the figure (the direction of the counter electrode) and collide with the sputtering prevention layer 16. At this time, since the hole 14 is located in the shadow when viewed from the ion direction B, the hole itself is easily deteriorated by ion sputtering.
The ions do not directly collide with the hole 14, and therefore,
The surface of the hole 14 will not deteriorate due to ion sputtering.

With the above structure, abundant electron emission and protection against ion sputtering can be simultaneously achieved.

Next, the composition and manufacturing method of the ceramic matrix IO will be described. The composition of the ceramic matrix 10 is XA (YyZ
x) Ceramic with ass structure, X part is Ba,
One or more elements selected from Sr and Ca are possible, the Y part is one or more elements selected from Zr and Ti, and the Z part is Ta, V, Mo, R.
u, Rh, ) If, *, Re, Os, Ir,
It is one or more elements selected from Nb. A typical substance for the part Z is a pentavalent metal with a melting point of 1800° C. or higher.

According to a preferred embodiment, X = Ba, Y = Z
r, Z=Nb, respectively Bad, ZrOx, Nt)+
The molar ratio of the raw materials of BaO, ZrOx and Nbtos is (0.5~1.5): (0.3~0
．． 7): (0,3:~0.7). More preferred embodiments of the above molar ratio are 1:0.6:0.4 or 1:0.6:0.2.

FIG. 3 shows a method for manufacturing a ceramic matrix IO, in which in step 20 materials (oxides of Ba, Sr, and Ca (e.g., BaO) and titanium or zirconate (e.g., ZrOs) are
) and Nb*Os) are mixed. Step 22 is the same as the normal ceramic manufacturing process, including mixing, calcination, fine pulverization,
The process includes granulation, mixing with binder, and molding. In step 24, baking is performed in air at 1300° C. to 1800° C. (more preferably in an oxygen atmosphere of about 1500° C.) for about 2 hours, but this step may be omitted in relation to the subsequent reduction treatment step 26. It is possible.

Reduction treatment 26 is an important feature of the present invention, and is performed at 1300°C to 1
Reduction treatment is performed for about 2 hours in a hydrogen (H8) atmosphere at 600℃.The conditions for the reduction treatment are a temperature of 1300 to 1600℃.
℃, more preferably 1450℃, the atmosphere is nitrogen containing hydrogen (may also include argon), preferably a mixture of hydrogen and nitrogen at a rate of 120ρ/h, hydrogen is 9.6
Adjust so that β/h (hydrogen concentration 8%).

As a result of the reduction treatment, the ceramic becomes a semiconductor, and Nb is added to the surface to act as a sputtering prevention layer 16.
A film with a thickness of 2 to 3 μm is deposited.

Note that the non-penetrating holes 14 where no sputtering prevention layer is present are formed by drilling after the reduction treatment, or after the sputtering prevention layer is attached to the holes, the sputtering prevention layer in the holes is removed.

Next, the experimental results of the electrode according to the present invention will be described.

Figure 4 shows experimental results regarding tube voltage and restriking voltage.
The experiment was conducted under the conditions of a frequency of 50 Hz and a tube current of 1 OmA (RMS), where A is an electrode according to the present invention, B is a conventional ceramic (BaTiOm) electrode, and C is a conventional metal (BaTiOm) electrode.
Ni) electrode, the almost rectangular curve A in each figure shows the tube voltage,
(A) ; (B) is 100V/scale, (C) is 200
V/scale. Curve B in the form of a sinusoidal wave shows the tube current, and in each figure, the effective value is 100 mA at 70 mA/scale.

From FIG. 4(A), the tube voltage of the electrode according to the present invention is approximately 60V.
, the restriking voltage is about 150v, and these values are shown in Figure 4 (B
) conventional ceramic electrode (tube voltage 60~gov,
It is not inferior to the restriking voltage (150V).

In other words, the electron emission characteristics of the electrode according to the present invention are equal to or higher than those of conventional ceramic and mixed electrodes. The nickel electrode in FIG. 4(C) has a tube voltage of 250 V and a restriking voltage of 440 V, and the material of the present invention has better electron emission characteristics than the conventional nickel electrode.

Figure 5 shows the experimental results of thermal shock tests of the present invention and conventional ceramic electrodes, (A) is a conventional ceramic electrode without reduction treatment, and (B) is a conventional ceramic electrode without reduction treatment. (C) shows the characteristics of the electrode according to the present invention.

“In each figure, the horizontal axis is the temperature difference (difference between the temperature heated in the furnace and the temperature of the cooling water), and the vertical axis is the bending strength (3-point bending test)
shows. In (A) and (B) of the figure, the characteristics deteriorate when the temperature difference is around 100°C, whereas in (C) of the figure (the present invention)
It can be seen that good characteristics can be obtained up to a temperature difference of around 250°C. Therefore, the electrode material according to the present invention
It can be seen that it is resistant to heat shock caused by N and OFF.

(Effects of the Invention) As explained above, the electrode according to the present invention has better emission and lower tube voltage and restriking voltage (therefore, a discharge lamp that does not require preheating can be obtained) compared to conventional metal electrodes. Also, since the emission is good, it is possible to obtain a discharge lamp with a small tube diameter.Also, it is possible to obtain an electrode that is more resistant to thermal shock than conventional ceramic electrodes and is not damaged by ion sputtering.

[Brief explanation of the drawing]

FIG. 1 is a structural example of a discharge electrode according to the present invention, FIG. 2 is an enlarged view of a ceramic matrix according to the present invention, FIG. 3 is a diagram showing the manufacturing process of an electrode according to the present invention, and FIG. FIG. 5 is a diagram showing the experimental results of the thermal shock test of the electrode according to the present invention together with the characteristics of the conventional electrode. lO: Discharge electrode 13; Insulator film 16; Splatter 16a, 16b; Groove 100; Glass tube 12; Ceramic matrix 14; Hole prevention layer 20; Conductor lead

Claims (2)

[Claims] (1) a first material selected from Ba, Sr, and Ca;
a second material selected from Zr, Ti, Nb, Ta,
V, Mo, Ru, Rh, Hf, W, Re, Os, Ir,
In a discharge electrode having a surface deposited layer made of a conductor or semiconductor compound containing the third material on the surface thereof, the ceramic composition includes a third material selected from the above, wherein the ceramic composition has a hole, and the surface A discharge electrode characterized in that the deposited layer is formed on a portion of the surface of the ceramic composition other than the surface of the hole. (2) The discharge electrode according to claim (1), wherein the precipitated layer is made of a conductor or semiconductor composition mainly containing Nb.