JPH0146977B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a cathode holding hermetic component suitable for use in cathode ray tube electron guns and the like. A color picture tube generally uses three electron beams to form a color image, and therefore the electron gun has a structure having three cathodes. FIG. 1 is a plan view of a cathode holding hermetic component with separately supported cathode supports.
In the figure, 1 is a cylindrical cathode support that houses a heater therein, 2 is a support fixed to a stator 3, and 4 is a rectangular cylindrical body formed at the tip of the support 2. The cathode support 1 is filled with an insulator to keep the cathode support 1 insulated. Three cathode supports 1 are arranged in a straight line to form a so-called in-line electron gun. in this way,
If each cathode support is supported separately, it will take a lot of man-hours to accurately set the position between each cathode and the spacing with respect to the first grid.Therefore, as an improvement to this drawback, there is a method in which the cathode supports are supported integrally. It is considered. FIG. 2 shows such a cathode holding hermetic component, in which a is a plan view and b is a partially sectional front view. In the figure, 5 is a cylindrical cathode support with a heater inside and a cathode at the tip (not shown), 6 is a rectangular cylindrical body, and 7 is a cylindrical body with three cathode supports 5 inside it. It is an insulator filled to maintain insulation. The three cathode supports 5 are arranged linearly in the cylindrical body 6 and held together to form an in-line shape. A mold is used to position the cathode support 5 on the cylindrical body 6. FIG. 3 is a sectional view of the cathode holding hermetic component of FIG. 2 during manufacture. In the figure, 10 is a lower mold made of carbon, and 11 is an upper mold. The lower mold 10 has a recess 10a and three projections 10b protruding from the bottom of the recess 10a, and the upper mold 11 has three holes 11a. The cathode supports 5 are fitted into the protrusions 10b of the lower mold 10, and the cylindrical body 6 is inserted into the recess 10a, and then pellets of glass, ceramic, etc. Load the powder. Thereafter, the upper die 11 is placed and pressed so that the cathode support 5 enters the hole 11a, and the insulator 7 is formed by firing at a predetermined temperature in an N ₂ atmosphere. Therefore, the cathode support 5 is accurately positioned and held relative to the cylindrical body 6 even through the insulator 7. By using the insulators 4 and 7 to hermetically hold the cathode supports 1 and 5 in this way, costs are reduced by reducing assembly man-hours, and reliability and quality are improved. It has been widely used in recent years because it has the effect of extending its life by reducing changes over time. In the cathode holding hermetic component using such an insulator, the adhesive surface 7a of the insulator 7 with the cylindrical body 6 and the adhesive surface 7b with the cathode support 5 are sufficiently firmly fixed as shown in FIG. 2b. Must be. When the electron gun is in use, the cathode support 5 reaches a high temperature of 750°C or higher, and when it is not in use, it is rapidly cooled down to room temperature. Adhesive strength must be strong enough to prevent it from falling off. Further, the insulator 7 needs to have sufficient heat resistance so that it will not melt or deform even when heated to 750° C. or higher. Conventionally, alumina or forstellite ceramics or hard glass have been used as hermetic seal insulators that satisfy these characteristics, but alumina or forstellite ceramics require metallization or other special treatments to bond with metals. It required a lot of adhesive bonding, which caused many problems in terms of man-hours, and hard glass had problems with heat resistance. Note that the cylindrical body 6 to which the insulator 7 is fixed is made of Fe-Ni alloy such as 42Ni-Fe alloy, which has a large coefficient of thermal expansion, so it is bonded at high temperature, and when the temperature returns to room temperature, the cylindrical body 6 becomes insulated. It acts to tighten the body 7, and the adhesion force of the adhesive surface 7a becomes strong. In addition, the cathode support 5 is made of Fe-Ni, commonly known as Kovar.
-Co alloy is used, and its coefficient of thermal expansion is set approximately equal to that of the insulator 7 from room temperature to the fixing point. FIG. 4 is a graph of thermal expansion characteristics of various parts of the cathode holding hermetic component. The horizontal axis is temperature (℃),
The vertical axis shows the elongation rate (Δl/l×10 ³ ). In the figure, A indicates the characteristics of the cathode support 5, B indicates the characteristics of the cylindrical body 6, and C indicates the characteristics of the insulator 7. In addition, each part must be subjected to specified hermetic processing (for example, 850℃ for 15 minutes).
This is the characteristic after applying. In characteristic c, R _T is the room temperature point, T _G is the transition point, T _D is the yield point, T _s 〓 _, 〓, T _s 〓
is the fixed point and P is the hot point. Here, the characteristic C is divided into two parts from the transition point T _G , and one of them is further divided into two parts from the yield point. And the transition point T _G
The characteristic of rapidly rising from T _s 〓 _, 〓 and dropping rapidly from the yielding point T _D shows the case of an insulator using ordinary hard glass, and it rises linearly from the transition point T _G The characteristics are for an insulator using ceramic. However, conventional products using hard glass have excellent adhesive strength, but
There was a problem in that the insulator flowed, causing the cathode support to shift and deteriorating the characteristics of the electron gun. In addition, products using ceramics such as can withstand high temperatures of 800℃,
In order to compensate for the weak adhesion strength of the adhesive interface, it is necessary to apply a glassy film to the metal interface, apply metallization treatment to the ceramic surface, or delay the crystallization time. The problem was that the number of man-hours increased and there were many unstable elements in the production process. The present invention was made to solve these conventional problems, and its purpose is to:
It is an object of the present invention to provide a cathode holding hermetic component for an electron gun in which an insulator does not flow even at a high temperature point and sufficient adhesion strength at an adhesive interface can be obtained. Hereinafter, the present invention will be explained in detail with reference to Examples. [Example 1] Zno was used as an insulator at 60% (the same below Wt%),
When a composition containing 25% B ₂ O ₃ , 10% Sio ₂ , and 5% Mgo is fired at 850°C using a mold as shown in Fig. 3, the structure shown in Fig. 2 is produced. , 4th
A cathode holding hermetic component having a crystallized glass insulator having the characteristics shown in the figure is obtained. This characteristic increases linearly from the room temperature point R _T ,
It rises rapidly from the transition point T _G and passes through the fixed point T _{s ,} , and then rises linearly again from the yielding point T _D to reach the high temperature point P. The characteristics of this crystallized glass are higher than those of conventional hard glass at its yield point T _D
The characteristics up to this point are the same, but the major difference is that the characteristics drop sharply at temperatures above the yield point T _D , whereas they do not drop at all and rise linearly. Therefore, it can sufficiently withstand even when placed in a vacuum state of 800°C, and the adhesive interface is firmly fixed, resulting in high reliability and long life characteristics. In other words, having an abnormal expansion region of T _G →T _s 〓 _, 〓→T _D indicates that an amorphous glass portion remains in the crystallized glass, and this reduces the adhesion strength of the adhesive interface. increases. Furthermore, as the characteristics approach characteristic A of the cathode support due to abnormal expansion, the insulator tends to tighten the cathode support, and the adhesion force during this period increases. In addition, thermal expansion occurs slowly between T _D → P without yielding, but because of this characteristic of not yielding, it does not flow, causing deformation of the cathode support or misalignment. It can withstand use up to 800℃. [Example 2] Insulators: 35% Zno, 24% B ₂ O ₃ , SiO ₂
12%, Al ₂ O ₃ 15%, MgO 2%, CaO 3
Even when using crystallized glass prepared by firing a composition containing 9% BaO at 830° C., the same characteristics as those shown in FIG. 1 were obtained. Next, in order to compare with Example 1 (No. 1) and Example 2 (No. 2), an example of hard glass with conventional characteristics (No. 2) was prepared.
3) and a table including an example of ceramic (No. 4) with characteristics. In addition to the composition and firing temperature of the insulator, this table also includes the shape of the thermal expansion characteristics, the adhesion of the adhesive interface, the deformation of the cathode support when vacuum treated at 800°C for 1 hour, and the swelling state of the insulator. etc. are shown.

【table】

[Table] In the case of No. 1 and No. 2 of the present invention, the adhesion force is so strong that even if you try to pull the cathode support to remove the insulator, the cathode support will yield first. The No. 4 one easily comes off with a force of about 2 kg. Also, No. 1 and No. 2 are 800
No change was observed even after being kept in a vacuum state for 1 hour at ℃, but in the conventional No. 3 insulator, the insulator swelled.
The cathode support becomes misaligned. In addition to No. 1 and No. 2, various other compositions containing 3 to 15% of alkaline earth metal oxides can be considered. In Figure 4, the characteristics are characteristic A and yield point T _D
Although there is an intersection point nearby, the curve does not necessarily have to be like this, and the yielding point T _D may be between characteristic A and characteristic A. As described above, according to the cathode holding hermetic component for an electron gun according to the present invention, the adhesive interface of the insulator has a strong adhesion force, and the cathode support does not displace, resulting in improved reliability and extended service life.

[Brief explanation of drawings]

Fig. 1 is a plan view of a cathode holding hermetic component in which the cathode support is supported separately, Fig. 2a is a plan view of a cathode holding hermetic component in which the cathode support is integrated, and Fig. 2b is a partially sectional front view. Fig. 3 is a cross-sectional view at the time of manufacture,
FIG. 4 is a graph of thermal expansion characteristics of various parts of the cathode holding hermetic component. 1, 5... cathode support, 2... support body,
4, 7... Insulator, 6... Cylindrical body, 10... Lower die, 11... Upper die, R _T ... Room temperature point, T _G ... Transition point, T _s 〓 _, 〓, T _s 〓 ...Fixation point, T _D ...Deflection point, P
...High temperature point.

Claims (1)

[Claims] 1. In a cathode holding hermetic component for an electron gun that insulates and holds a cathode support in a cylindrical body, it expands abnormally from the transition point to the yielding point due to thermal expansion characteristics, exhibiting almost the same elongation rate as the cathode support, and above the yielding point, A hermetic part for holding a cathode for an electron gun, characterized by being insulated and held by crystallized glass containing amorphous material that increases elongation rate without yielding.