JP3828487B2 - Non-evaporable getter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a getter for maintaining the inside of a container at a high vacuum, and more particularly to a non-evaporable getter.
[0002]
[Prior art]
In a vacuum device such as a field emission display, micromachine device, infrared sensor, etc., in which components such as electrodes are sealed inside the container and the inside of the container is evacuated to a high vacuum, residual gases that could not be exhausted and the interior of the container A getter is used to adsorb the gas released from the components and maintain a high degree of vacuum. In addition, getters are also used to maintain the degree of vacuum in devices that use vacuum insulation such as magic bottles.
[0003]
There are two types of getters: an evaporative getter that places getter material in a container and heats it to evaporate, and a non-evaporable getter that does not need to evaporate the getter material. In addition, non-evaporable getters are preferably used because there is no fear that the evaporated getter material adheres to components such as electrodes.
[0004]
Non-evaporable getters usually use a porous alloy mainly composed of zirconium (Zr) as the getter material, and the active gas remaining in the vacuum is decomposed on the surface of the getter material, and the getter material and oxide It is chemically adsorbed by forming nitrides and carbides. As the surface of the getter material saturates with the adsorbed gas, the adsorption rate decreases, but the getter material surface is heated by heating the getter material to promote the diffusion of adsorbed gas components into the getter material (called activation). Becomes cleaner and allows further adsorption.
[0005]
Thus, since the non-evaporable getter does not release the adsorbed gas to the outside, it can be placed in a closed system and used as a vacuum pump for improving the degree of vacuum. Since there is no moving part and it can be reused by activation, it has been widely used in vacuum devices such as field emission displays, micromachine devices, and infrared sensors that need to keep the inside of the container in a vacuum.
[0006]
By the way, in the conventional non-evaporable getter, zirconium and other metal materials are dissolved to form an alloy, and the obtained alloy is pulverized and then pressed into a predetermined shape to obtain a getter material. For this reason, part of the getter material may be detached as microparticles (fine particles) due to vibration during transportation or use, or heating under low vacuum, etc., and may damage components such as electrodes inside the container. It was. Further, when such a getter is used for an infrared sensor or the like, the detached microparticles may adversely affect the captured image.
[0007]
On the other hand, Patent Document 1 discloses a method for manufacturing a getter material in which an alloy powder and an organic compound powder are mixed, pressed, and fired. However, the getter material fired in this way is mechanically weak because it is porous, and microparticles are detached due to vibrations, etc., damaging the components in the container and adversely affecting the sensor image. Sometimes
[0008]
By the way, non-evaporable getters can be classified into two types according to the activation method. One is a getter incorporating a heater for activation, and the other is a getter that is not provided with a heater and is activated by heating from the outside. The former heater built-in type getter is formed by pressing (and firing) the alloy powder around the heater, and the heater lead wire protrudes from the getter material. It can be fixed in a container. On the other hand, a getter without the latter heater does not have such a lead wire and is difficult to fix in the container. When the getter is not fixed, the getter collides with the inner wall of the container during transportation, movement, or in use, and the microparticles are more easily detached.
[0009]
Therefore, in the infrared detector disclosed in Patent Document 2, a getter is arranged in the getter case, and a filter through which gas passes but solids such as dust do not pass between the inner cylinder in which the infrared detection element is arranged. The microparticles detached from the getter material are kept away from the infrared detecting element so that the obtained image is not adversely affected.
[0010]
However, the method disclosed in Patent Document 2 cannot be applied to a small vacuum device in which it is difficult to provide a getter case. In addition, since the high-performance filter is held so as not to be damaged, there is a drawback in that the configuration is complicated, the manufacturing is troublesome, and the cost is high.
[0011]
Furthermore, as disclosed in Patent Documents 1 and 2, the conventional getter is formed by molding and firing a metal alloy powder, and thus there is a problem that the process for molding and firing takes time and cost. The surface area that contributes to gas adsorption is reduced by pressing during molding, and the getter material is deteriorated by firing, so that there is also a problem that the adsorption ability as a getter is lowered.
[0012]
[Patent Document 1]
JP-A-8-225806 [Patent Document 2]
Japanese Patent Laid-Open No. 10-332478
[Problems to be solved by the invention]
Therefore, an object of the present invention is to obtain a getter that does not require integral molding by pressing or baking and that does not detach microparticles.
[0014]
It is easy to fix the getter and can be applied to small vacuum devices. Even if the getter material breaks due to vibration or impact during transportation, movement or use, the getter material The object is to obtain a getter in which debris does not detach into the vacuum device.
[0015]
[Means for Solving the Problems]
The present invention relates to a non-evaporable getter formed by surrounding a powdery getter material with a mesh, and the mesh is made of a material that does not react with the getter material and has finer stitches than the getter material.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings, but the present invention is not limited to these embodiments.
[0017]
Embodiment 1
As shown in FIG. 1, the non-evaporable getter of the present embodiment is formed by surrounding a getter material 1 and a heater 3 for activation with a mesh 2.
[0018]
The getter material 1 is, for example, a metal such as Zr, Ti, Nb, V, or Ta, or an alloy such as Zr—Al, Zr—V, Zr—Fe, Zr—Ni, Zr—Mn—Fe, or Zr—V—Fe. Consists of. Among these metals and alloys, Zr—V—Fe or Zr—Al is preferable in terms of adsorption characteristics.
[0019]
These metals and alloys are used after being pulverized into a powder having a particle size of about 20 to 200 μm, preferably about 50 to 100 μm. When the particle size is larger than 200 μm, heat conduction tends to be poor and heating tends to be difficult. When the particle size is smaller than 20 μm, adsorption tends to saturate immediately because it is a fine powder.
[0020]
The mesh 2 is made of a material that does not react with the getter material 1 and has a finer mesh than the getter material 1.
[0021]
Here, “does not react” means a property that does not deteriorate when contacted with a getter material at a high temperature. Examples of materials that do not react with the getter material include stainless steel and nichrome alloy. In particular, when the getter material is made of Zr-V-Fe, activation by high temperature is necessary, and therefore stainless steel is preferably used.
[0022]
The mesh of the mesh 2 needs to be smaller than the particle diameter of the getter material 1 so that the getter material 1 does not pass through the mesh, but if the mesh of the mesh 2 is close to the particle diameter of the getter material 1, A part of the material 1 may pass through the mesh 2 mesh. Further, there may be a case where the getter material 1 is damaged in the mesh 2 due to vibration or impact, and the fragments are detached after passing through the mesh of the mesh. Therefore, when the particle diameter of the getter material is 20 to 50 μm, a mesh with an opening of 5 to 10 μm may be used. When the particle diameter of the getter material is 50 to 100 μm, the opening of 10 to 20 μm is used. Use a mesh. If the mesh opening is larger than 20 μm, part of the getter material or fragments of the getter material may be detached into the vacuum container. If the mesh opening is smaller than 5 μm, the gas flow Will deteriorate the adsorption speed.
[0023]
These meshes 2 are molded into a shape such as a bag, cylinder, sphere, or box, and a getter material 1 and a heater 3 are disposed inside.
[0024]
The heater 3 is, for example, a heating wire made of W (tungsten) or a resistor made of Ni—Cr, and is arranged in the mesh 2 together with the getter material 1. In the case of a heater made of W (tungsten), it is preferable to be insulated with alumina. The lead-out line of the heater 3 is drawn out of the mesh 2, and the non-evaporable getter of the present embodiment can be fixed in the container by using the lead-out line.
[0025]
In the present embodiment, a powdery getter material obtained by pulverizing an alloy is enclosed in a mesh together with a heater. For this reason, compared to the conventional heater built-in non-evaporable getter that presses and fires the getter material integrally with the heater, it is easy to manufacture without pressing and firing, and there is no deterioration of the getter material due to firing. Therefore, a getter with higher adsorption ability can be obtained.
[0026]
Further, since the crushed getter material is used as it is surrounded by a mesh, it is unlikely that the getter material will be further crushed by vibration or impact. Therefore, the getter material does not fall into the container through the mesh, and the components in the container are not damaged or the sensor image is not adversely affected. Furthermore, by using a mesh having a smaller mesh opening, even if the getter material is damaged, it is possible to prevent the fragments from falling into the vacuum container.
[0027]
As described above, the non-evaporable getter of the present embodiment is easy to manufacture, has a high adsorption capability, and is strong against vibration and shock, and therefore can be preferably used particularly in a vacuum device of a portable device or an in-vehicle device. .
[0028]
Embodiment 2
The non-evaporable getter of the present embodiment shown in FIG. 2 is a heaterless getter that does not include a heater for activation inside, and is obtained by surrounding the getter material 1 with a mesh 2.
[0029]
In the present embodiment, as the getter material 1 and the mesh 2, the same getter material and mesh as those in the first embodiment can be used.
[0030]
In the present embodiment, a powdery getter material obtained by pulverizing an alloy is enclosed in a mesh as it is. For this reason, compared to conventional non-evaporable getters that are molded by pressing powdery getter material, it is easier to manufacture without pressing and has a larger surface area that contributes to gas adsorption, so it has higher adsorption capacity. Getter can be obtained. Compared to conventional non-evaporable getters that press and fire a powdered getter material, it is easier to manufacture without pressing and firing, and has no higher deterioration of the getter material due to firing. Getter can be obtained.
[0031]
Further, since the crushed getter material is used as it is surrounded by a mesh, it is unlikely that the getter material will be further crushed by vibration or impact. Therefore, the getter material does not fall into the container through the mesh, and the components in the container are not damaged or the sensor image is not adversely affected. Furthermore, by using a mesh having a smaller mesh opening, even if the getter material is damaged, it is possible to prevent the fragments from falling into the vacuum container.
[0032]
In addition, the non-evaporable getter of the present embodiment is a getter that is heaterless and has no heater lead wire by, for example, providing the mounting seat 4 on the container 5 and welding the mesh 2 to the mounting seat 4. It can be easily fixed in the container. As described above, in the non-evaporable getter according to the present embodiment, the mesh 2 can be used to fix the inside of the container. Therefore, a conventional heaterless getter formed by pressing (and firing) a powdery getter material. Unlike the case where it is used for a vacuum device of a portable device or an in-vehicle device in which vibration and impact are expected, it is not necessary to provide a getter case for storing a getter in the container. Therefore, according to this embodiment, it is possible to install a heaterless getter even in a small vacuum device in which it is difficult to provide a getter case.
[0033]
【The invention's effect】
According to the present invention, since the powdery getter material is surrounded by a fine mesh, the getter material is not detached into the vacuum vessel and the components in the vessel are not damaged. Further, even when a sensor or the like is arranged in the container, its operation is not adversely affected.
[0034]
Furthermore, since the powdery getter material is used as it is and is not pressed or fired, the surface area contributing to gas adsorption is large, the getter material is not deteriorated, and a getter with higher adsorption ability can be obtained. . Further, since it is not pressed or fired, it is easy to manufacture.
[0035]
Furthermore, since the non-evaporable getter of the present invention can be easily fixed in a container using a mesh, it is not necessary to provide a getter case for storing the getter and can be applied to a small vacuum device. is there.
[0036]
Moreover, by providing a heater in the mesh, the getter material can be activated without heating the entire vacuum device from the outside. Furthermore, since the getter can be fixed using the lead wire of the heater, the getter does not move due to acceleration such as vibration or impact, and further prevention of breakage of the getter material and detachment into the container can be further prevented. it can.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a non-evaporable getter according to an embodiment of the present invention, showing a non-evaporable getter having a structure in which a heater and a powdery getter material are surrounded by a mesh.
FIG. 2 is a cross-sectional view showing a non-evaporable getter according to another embodiment of the present invention, showing a non-evaporable getter without a heater for activation.
[Explanation of symbols]
1 Getter material, 2 mesh, 3 heaters, 4 mounting seats, 5 containers.

Claims (2)

A non-evaporable getter comprising a powdery getter material surrounded by a mesh, wherein the mesh is made of a material that does not react with the getter material and has finer stitches than the getter material. 2. The non-evaporable getter according to claim 1, further comprising a heater for activating the getter material, wherein a lead wire of the heater is drawn out of the mesh.

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