JPS6231470B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron gun used in a cathode ray tube, and particularly relates to a plurality of grid electrodes. The present invention relates to a cathode ray tube electron gun having a directly heated shade whose spacing is adjusted and maintained, and a method for assembling the same.

In recent years, cathode ray tubes for use in television sets are desired to consume less power, and this can be achieved by reducing the deflection power or the cathode heating power.

For example, in the case of a three-electron gun for color cathode ray tubes, especially when the deflection power is low, the diameter of the neck part of the cathode ray tube becomes thinner, and therefore the diameter of the electron gun housed in the neck part also becomes thinner. The distance between each unit becomes narrower. Such an electron gun structure includes a first grid electrode, a second grid electrode, a third grid electrode, a fourth grid electrode, etc., which are integrally assembled at predetermined intervals by an insulating support rod such as glass. As a small-diameter electron gun, each grid electrode has a common structure of a single three-electron gun, and has the same potential. Therefore, the signal input to the three electron guns is added to the cathode potential and modulated. Therefore, the spacing between the cathode and grid electrodes must be set extremely accurately. The present invention provides means for adjusting the relationship between the electron emission part and the first grid electrode, thereby setting the distance between the electron emission part and the first grid electrode to an appropriate value, and correcting variations in the electron gun. The purpose is to

Embodiments of the present invention will be described below with reference to the drawings. First, a case where the present invention is applied to an in-line three-electron gun will be explained using FIG. Inline type 3
The electron gun includes a plurality of opposing insulating support rods 17, 1.
7', a fourth grid electrode 16, a third grid electrode 15, a second grid electrode 14, a first grid electrode 13 and a cathode 2.
0 are fixed at predetermined intervals. The fourth grid electrode 16 and the third grid electrode 15 are common to the three electron beams, and are phase electrodes having three beam passing holes linearly formed, and the second grid electrode 14 and the first grid electrode 13 are flat plate shaped electrodes. It has three beam passage holes like the above. Further, as shown in FIG. 2, the cathode 20 is suspended between the substrate 1, support rods 2 and 3 that are spaced apart from each other and are supported through the substrate 1, and the support rods 2 and 3. filament 5
, an electron emitting section 7 placed on the filament 5, and means for adjusting the relationship between the first grid electrode 13 and the electron emitting section 7. Figure 2,
This will be explained in more detail using FIGS. 3 and 4. FIG. 3 is a perspective view of the cathode assembly according to the present invention viewed from the back side, and FIG. 4 is a diagram illustrating the cathode assembly according to the present invention and its assembly method. Reference numeral 1 denotes a substrate made of ceramic or the like, which is placed opposite the beam passage hole (not shown) of the first grid electrode, which will later be integrated with an insulating support rod (bead glass).
It has a plurality of insertion holes 22 and cutouts 23 for supporting the pair of conductive support rods 2 and 3. A stepped portion 24 is provided at the inner shoulder portion of the insertion hole 22 and the cutout portion 23 to store adhesive glass for adhesively fixing the substrate 1 and the support rods 2 and 3 after the support rods 2 and 3 are penetrated or fitted. have. (The stepped portion on the insertion hole side is not shown). A through hole 21 is provided between the insertion hole and the notch so as to correspond to the beam passage hole of the first grid electrode. Moreover, a groove 50 is provided between each set of conductive support rods 2 and 3 on the upper surface of the insulating substrate 1 so as to separate them. Further, on the lower side of the substrate 1, there is a support plate 1 consisting of a pair of support rods 2 and 3 and a single plate disposed between another pair of support rods 2 and 3 to support the substrate.
A slit 25 for fitting and fixing the adhesive glass is formed in the center of the slit 25, and a recess 25' for inserting adhesive glass is formed in the center of the slit 25.

One support rod 2 of a pair of conductive support rods 2 and 3, which are arranged at a predetermined distance from each other so as to penetrate through the substrate 1, supports the electron emitting part, that is, the cathode 7. One end of the filament 5 placed in the center is fixedly supported, and the other support rod 3
has an elastic force by fixing the other end of the filament 5 to an elastic member 4 fixed to the support rod 3 such that one end thereof extends outside the support rod 3. and the distance between the first grid electrode (hereinafter also simply referred to as G ₁ ) and the cathode (hereinafter simply referred to as K) (hereinafter simply referred to as G ₁ K
The movable member 8 is formed into a rectangular hollow body so as to serve as a guide portion for a movable member 8 that comes into contact with the filament 5 to adjust its height in order to maintain a predetermined interval. The support rod 2 on _the side where the filament 5 of this conductive support rod is fixed (hereinafter also referred to as the fixed side support rod) penetrates the insertion hole 22 of the substrate 1 and is fixed with adhesive. Elastic member 4 to adjust
A movable support rod 3 (hereinafter also referred to as a movable support rod) having a movable member 8 is fitted into the notch 23 of the substrate 1 and fixed by adhesive. An elastic member 4 attached to the movable support rod 3 to fixedly support one end of the filament 5 absorbs the elongation due to thermal expansion of the filament 5 when the filament 5 is heated by igniting the filament 5 and passing a current. This is to give the fimment 5 elasticity so that it can move from position 7. 7 is the cathode
An electron emitting material such as BaSr or CaCO ₃ is coated on the upper surface of a cathode base metal made of a Ni-based alloy containing Mg, Si, W, etc. The movable member 8 is used for adjusting the distance between the first grid electrode 13 and the electron emitting surface of the cathode 7 to a predetermined distance.
After embedding the plurality of grid electrodes and the substrate 1 in an insulating support rod and assembling them together, the cathode 7 is inserted into the movable side support rod 3 in order to adjust the placement position of the cathode 7, and this movable side support The rod 3 is used as a guide for movement. Further, as shown in FIG. 4, the fixed dimensions of the fixed side support rod 2 and the movable side support rod 3 are unique to the present invention. That is, the heights of the fixed support rod 2 and the movable support rod 3 from the surface of the substrate 1 are set such that the movable support rod 3 is lower than the fixed support rod 2 by about 0.1 to 0.15 mm.
Therefore, the filament 5 stretched by the fixed support rod 2 and the elastic member 4 is non-parallel to the substrate 1 and the first grid electrode 13.

Here, a method of assembling an electron gun equipped with such a directly heated cathode will be explained. First, a gear spacer 30 that determines the distance between G ₁ 13 and the substrate ₁ is attached to G ₁ 13, which has a cylindrical shape with a bottom as shown in FIG.
After inserting the board 1, and then inserting the retainer 3
1, or as shown in _FIG .
It can be applied to any method in which a temporary G ₁ K spacing is created by, for example, fixing a directly heated cathode between the two. After setting the temporary G ₁ K interval in this way, the fourth
As shown in the figure, multiple grid electrodes and directly heated cathodes are embedded in an insulated support rod (not shown) and assembled into one piece.
Using G ₁ 13 or G ₂ 14 as a reference plane, the tip of the movable member 8 is brought into contact with the lower surface of the filament 5 from below while measuring the G ₁ K interval using an air micro, capacitance, or optical method. Move the vicinity of the end of the filament, which has been set lower in advance, upward (arrow a) so that the filaments become parallel. By moving the movable member 8 in this way, move the movable member 8 to the movable side by adjusting the movement while measuring the G ₁ K interval so that the upper surface of the filament 5 becomes parallel to the G ₁ 13. The movable member 8 is welded and fixed to the support rod 3, and one side of the filament 5 is supported at the tip of the movable member 8. The theoretically best G ₁ K spacing is preferably one in which the filament 5 and G ₁ 13 are parallel. However, filament 15
Although it is not always possible to achieve an accurate parallel state due to the tensioned state of the suspension or variations in the dimensions of the fixed support rod 2, this can be corrected by adjusting the position of the movable member 8. That is, since one end of the filament 5 is fixed to the fixed support rod 2 provided on the substrate 1, one end of the filament 5 cannot be moved after assembly, so that G ₁ 13 and the cathode 7 are Although they may not be parallel, the diameter of the through hole that contributes to the electron emission of G ₁ 13 is extremely small at 0.5φ to 0.8φ, and this
Since the accurate G ¹ K spacing can be determined by measuring the spacing between the G ₁ through hole and the cathode electron emitting surface directly below it, the characteristics of the electron gun will not deteriorate due to parallelism errors.

In this way, the electron gun according to the present invention can be adjusted while measuring the G _{1 K interval after assembling a plurality of grid electrodes and directly heated cathodes using insulated support rods, and can achieve extremely accurate G 1 K} spacing. It is possible to obtain an electron gun with a spacing. Here, the movable member that is incorporated into the directly heated cathode when adjusting the G ₁ K interval of the electron gun will be explained. As shown in FIG. 4, this movable member 8 comes into contact with the lower surface of the filament 5 when adjusting the filament position, and pushes it up toward the G ₁ 13 side to adjust the G ₁ K interval. , is slidably inserted into the hollow movable support rod 3, and its tip is rounded so as not to damage the filament 5. When adjusting the filament 5 on the fixed side support rod 2,
The upper surface is used as a reference and the upper surface is moved closer to the upper surface, that is, parallel to G ₁ 13. However, if the upper surface of the fixed end of _the filament 5 deviates from the reference 41 located at a predetermined G ₁ K interval of the directly heated cathode, In order to maintain the filament 5 in a predetermined position while measuring the G ₁ K interval, it is also conceivable that the filament 5 is stretched slightly diagonally. The inventors of the present application consider that the movable range is about ±0.1 mm from the reference plane 41, and since the cathode 7 is located approximately in the center between the fixed support rod 2 and the movable support rod 3, the actual The adjustment range is half of this. Therefore, with this adjustment range, there will be errors when fixing the stationary side support rod to the substrate, errors in the flatness of each beam hole in _G1 , and errors in cathode height when assembling the directly heated cathode. It is possible to absorb all of , and make the G ₁ K spacing constant. This movable member 8
is formed into a rectangular shape as shown in Figures 7a, b, and c, and its cross section is rectangular [7th
(see Figure 7a), a rectangular shape with rounded short sides (see Figure 7c), or a long ribbon folded in two (see Figure 7b).

The filament current characteristics when such a movable member is used will be explained. First, looking at how the current flows with reference to FIG. Since the member 4 is a spring and has a relatively small cross-sectional area, its resistance value is large. Therefore, the resistance value of the circuit that flows from the contact portion between the movable member 8 and the filament 5 to the movable member 8 and reaches the movable support rod 3 is lower. Therefore, from the middle of the circuit of fixed side support rod 2 - filament 5 - elastic member 4 - movable side support rod 3, fixed side support rod 2 - filament 5 - movable member 8
- The circuit of the movable side support rod 3 is added in parallel, and the filament current increases, but since the contact resistance of the contact portion between the filament 5 and the movable member 8 varies depending on the pressure and the contact area, variations in the filament current occur. This variation changes the temperature of the cathode 7 and affects the electron emission characteristics. If the three electron guns become misaligned, it will be difficult to adjust the white screen (in the case of a C-CRT). In addition, if the contact deteriorates, the cathode temperature increases and the evaporation of BaO, which is an electron emitting substance, is promoted, reducing the electron emitting ability and shortening the lifespan. In such a case, the temperature of the filament 5 increases, causing coarsening of the Ni--W alloy that is the material of the filament, and since tension is applied by the elastic member 4, the wire is likely to break during use.

In this way, the filament current changes depending on the quality of the contact. For example, when a shock is applied to a cathode ray tube, the resistance at the contact point changes and the cathode temperature changes, causing the problem of nozzle formation. Stabilizing the electrical resistance and thermal conductivity of such contact points is a serious problem when tension is applied to the filament, and even if there are slight fluctuations in tension, the contact resistance It is desirable that there be no difference in Therefore, the filament 5 and the movable member 8
It is desirable that a certain amount of pressure be applied (for example, about 2 g of tension from an elastic member holding a filament). That is, it is desirable that the contact points between the filament and the movable member have poor electrical conductivity and poor thermal conductivity under this pressure. For this, the contact part of the movable member with the filament,
This is possible by covering with Cr oxide or Al oxide. Taking chromium oxide as an example, as shown in Fig. 8, the contact part (tip part) of the movable member 8 that contacts the filament is plated with Cr and baked in a hydrogen furnace.
Cr treated in a hydrogen furnace with water addition at approximately 1200℃
Only the layer is oxidized to generate a chromium oxide layer 80, which adheres closely to the surface. This chromium oxide layer 80 has a surface resistance of 1 MΩ, and is not worn away by contact pressure and friction during intermittent tests, so that the above-mentioned problems can be solved.

Figure 9 shows a Cr-containing metal alloy, such as stainless steel or nichrome, made by cladding or plating nickel and molding it, with the Cr-containing layer exposed only in the semicircular part that contacts the filament, and the Cr-containing layer is exposed in the above treatment process. A chromium oxide layer 80 can be generated only on exposed parts.

The one in Figure 10, like the one in Figure 9, is made by cutting a Cr-containing alloy on the core metal and a non-Cr-containing metal on the outer sheath, and has a chromium oxide layer 80 adhered to the side surface. ing. What is shown in FIG. 11 is a movable member 8 formed by bending a plate-shaped material.After applying Cr plating to the abutting portion, oxidation treatment is performed to cover the Cr plating layer with a chromium oxide layer 80. However, after cladding the surface with a non-containing metal and bending it, it peels off and oxidizes. In any case, a chromium oxide coated surface is formed on the contact part with the filament,
The objective can be achieved by forming a non-oxidized layer in the welding direction. Similarly, the same effect can be obtained by depositing an aluminum oxide layer on the surface of the Cr alloy material described above using kanthal or the like having a high Al content.
Although these chromium oxides and aluminum oxides cannot be said to be perfect insulators, the electrical resistance depends on the entire length of the filament.
1.5Ω, which is very small at 0.2 to 0.3Ω from the spacer contact portion to the end, and theoretically a difference in contact resistance of three orders of magnitude or more is sufficient. Similarly, chromium oxide and aluminum oxide conduct heat less easily than metals, so heat loss is also reduced. In addition, the oxide layer deposited on the surface of the metal is compatible with the metal and has sufficient strength against friction caused by filament interruption during assembly or use.

Regarding the electron gun of the present invention, a three-electron gun structure for color has been explained as an example, but the G ₁ K spacing adjustment method of the present invention can also be applied to single electron guns such as monochrome cathode ray tubes, image pickup tubes, and other industrial cathode ray tubes. It is possible and its effectiveness can be fully demonstrated.

[Brief explanation of the drawing]

1a and 1b are partial cross-sectional views and side views of an electron gun according to the present invention, FIGS. 2 and 3 are enlarged perspective views of essential parts of the present invention, and FIG. 4 is a cathode structure and its assembly according to the present invention. 5 and 6 are explanatory views of an electron gun assembly and its assembly method, and FIGS. 7 to 11 are perspective views of a movable spacer according to the present invention. and a top view. 1...Insulating board, 2...Fixed side support rod, 3...
Movable side support rod, 4... Elastic member, 5... Filament, 7... Cathode, 8... Movable member, 80...
...Chromium oxide layer.

Claims (1)

[Claims] 1. In a cathode ray tube electron gun in which a plurality of grid electrodes and a cathode are fixed to a pair of bead glasses, the cathode includes: an insulating substrate 1; and a conductor fixed to the insulating substrate 1. a filament fixed side support rod 2; and a hollow conductor made of a hollow conductor fixed to the insulating substrate 1 and spaced apart from each other at a predetermined interval so as to form a pair with the fixed side support rod 2 and whose height is lower than that of the fixed side support rod 2. a filament movable support rod 3; an elastic member 4 fixed to the outer wall of the movable support rod 3, one end of which is fixed to the fixed support rod 2, the other end of which extends above the movable support rod 3; a filament 5 fixed to the elastic member 4 and provided with an electron emitting section in the middle; and a filament 5 inserted through the movable support rod 3, with the tip end of the fixed support rod being closer to the movable support rod 3. 2, the movable member 8 is partially fixed to the movable support rod 3, the movable member 8 protrudes to a height substantially equal to that of the filament 5, and lifts the filament 5 by contacting the filament 5. gun. 2. An electron gun for a cathode ray tube according to claim 1, wherein the movable member 8 is coated with a high-resistance layer on the tip end surface that comes into contact with the filament 5. 3. A method of assembling an electron gun for a cathode ray tube in which a plurality of grid electrodes and cathodes are fixed to a pair of bead glasses, comprising: an insulating substrate 1; a filament fixing side support rod 2 made of a conductor fixed to the insulating substrate 1; a filament movable side support rod 3 made of a hollow conductor fixed to the insulating substrate 1 at a predetermined interval and lower in height than the fixed side support rod 2 so as to form a pair with the side support rod 2; An elastic member 4 fixed to the outer wall of the support rod 3, and one end of which is connected to the fixed side support rod 2.
A cathode having a filament, the other end of which passes over the movable support rod 3 and is fixed to the elastic member 4 and has an electron emitting section in the middle, is held in a predetermined positional relationship with a plurality of grid electrodes. Next, the movable member 8 is inserted into the movable side support rod 3 of the cathode, and its tip protrudes beyond the tip of the movable side support rod 3 to contact the filament 5. The step of adjusting the distance between the grid electrode and the electron emitting part by bringing them into contact with each other and lifting them, and fixing a part of the movable member 8 to the movable support rod 3 while maintaining a predetermined distance. Features: Assembling method of electron gun for cathode ray tube.