JPS6328513Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a directly heated cathode structure suitable for use in, for example, a three-electron gun of a color picture tube. Generally, a color picture tube has a built-in in-line three-electron gun, and this type of three-electron gun is composed of a directly heated composite cathode structure, first to fourth grid electrodes, and the like. By the way, one of the directly heated composite cathode structures that has been proposed is shown in FIG.
This directly heated composite cathode structure is seen from diagonally above, and is made up of three cathode structures, including an insulating substrate 1 made of ceramics, a pair of conductive filament supports 2, Three insertion holes 4 and three notches 5 are provided to support the holder 3. The insertion hole 4 and the inner shoulder part of the notch 5 are provided with an adhesive for adhering and fixing the insulating substrate 1 and the pair of supports 2 and 3 after passing through or fitting the pair of supports 2 and 3. A stepped portion (not visible in the figure) is formed for storing components. Furthermore, grooves 6 and 7 of a predetermined depth are provided on the upper surface of the insulating substrate 1 between the three sets of cathode conductors. 1 disposed at a predetermined distance from each other so as to penetrate through such an insulating base 1.
Of the pair of supports 2 and 3, the first support 2 fixedly supports one end of a filament 10 on which a base metal plate 8 and an electron emitting material layer 9 are placed in the center, and the second support 3 The other end of the filament 10 is connected to the support 3
The support body 3 is fixed to a spring member 11 fixed to the support body 3 so that one end thereof extends outwardly from the support body 3, thereby being supported so that a resilient force is applied thereto.
In addition, the second support 3 serves as a guide for a movable adjustment rod 12 that comes into contact with the filament 10 and adjusts its height in order to maintain a predetermined distance from the first grid electrode (not shown). It is formed into a rectangular hollow body. The first support body 2 on the side to which the filament 10 is fixed penetrates into the insertion hole 4 of the insulating substrate 1 and is adhesively fixed, and the spring member 11 adjusts the relationship between the first grid electrode and the electron emission layer 9. The second support 3 on the movable side, which includes the movable adjustment rod 12, is fitted into the notch 5 of the insulating substrate 1 and fixed by adhesive.
A spring member 11 provided to fixedly support one end of the filament 10 on the second support body 3 absorbs the elongation due to thermal expansion of the filament 10 or changes the position of the filament 10 when the filament 10 is heated by passing current through it. It has elasticity so that it can move up and down. Further, the electron emitting material layer 9 is coated on the upper surface of the base metal plate 8 formed of a Ni-based alloy containing Mg, Si, W, etc. (Ba,
Sr, Ca) CO ₃ oxide, which emits thermoelectrons when activated in a later process. Further, as described above, the movable adjustment rod 12 is used for adjusting the distance between the first grid electrode (not shown) and the electron emitting material layer 9 to a predetermined value, and is used to adjust the distance between the plurality of grid electrodes and the insulating substrate 1. For example, after implanting it in bead glass and assembling them together, it is inserted into the second support 3 in order to adjust the placement position of the electron emitting material layer 9, and along this second support 3. It moves up and down and is finally fixed to this second support 3 by means such as welding. However, in the above-mentioned directly heated cathode structure, the filament is pulled in the horizontal direction by a spring member, but when the movable adjustment rod is moved to adjust the height of the electron emission surface, even a slight change in the height can cause the tension on the filament to be reduced. It tends to change significantly. Since the filament is extremely thin and its tensile strength at high temperatures is not very high, it is prone to breakage if excessive tension is applied during height adjustment. Furthermore, if the contact surface between the filament and the adjustment rod does not always slide smoothly, there is a risk that the electron emitting surface will bounce and change every time the filament is ignited. On the other hand, a directly heated cathode disclosed in Japanese Utility Model Application Publication No. 53-85959 is known, but this also uses a spring member to provide tensile force, but a position regulating member is placed below the filament. As described above, it is not easy to always maintain perfect sliding of the contact surface between the filament and the position regulating member, and the electron emitting surface tends to bounce. On the other hand, a cathode structure shown in Japanese Utility Model Publication No. 43-3700 is also known. This is a structure in which the width direction of the thin filament is parallel to the electron gun axis. However, while the change in the height of the electron emitting surface is suppressed, since only a part of the filament is simply bent, the direction of movement of the electron emitting part is not constant due to deformation due to intermittent heating of the filament. There is a conceivable problem that the relative position of the one-grid electrode with respect to the beam aperture changes in an undesirably complicated manner. The present invention solves the above-mentioned disadvantages of the conventional technology and is a direct heating system with a structure in which there is almost no change in the height of the electron emitting surface, and the movement of the electron emitting part due to intermittent heating of the filament is restricted to a certain direction or hardly moves. The present invention provides a type cathode structure. A first embodiment of the directly heated cathode assembly of the present invention will be described below with reference to FIGS. 2 to 6. That is, the directly heated cathode structure 20 has a first insulating support plate 21 formed of ceramics or the like, which will be described later.
and a second conductive filament support 22, 2
3 and the spring support 24 are inserted and penetrated and fixed with an adhesive member such as adhesive glass or brazing material.
The insulating support plate 21 is formed with an insertion hole 23 ₄ having a stepped portion 23 ₁ and a positioning opening 21 ₂ for this purpose. Then, it is inserted into the cathode tube 26 so as to surround the side wall portion of the insulating support plate 21. Now, between the side wall parts 22 ₁ and 23 ₁ near the top of each of the first and second supports, a width of 0.2 to 0.5 mm and a thickness made of, for example, 70% by weight of Ni and 30% by weight of W is provided.
Ribbon-like filaments (hereinafter referred to as filaments) 28 with a diameter of 0.02 to 0.04 mm are installed at welding points 22 ₂ and 23 ₂ , respectively. In this case, the width direction of the filament 28 is parallel to the electron gun axis Z of the directly heated cathode assembly 20. Also, a spring member 2 is attached to the side wall portion 24 ₁ near the top of the spring support 24 .
9 is in elastic contact with the filament 28 via the welding point 24 ₂ so as to apply an appropriate elastic force in the longitudinal direction of the filament 28, that is, in the direction perpendicular to the electron gun axis. That is, the spring member 29 has a width (W2) larger than the width (W1) of the ribbon-like filament, as shown in FIG. They are in parallel line contact and push the entire side surface of the filament in a direction perpendicular to the electron gun axis. Further, an electron emitter 30 having a structure described in detail below is mounted and fixed approximately at the center of the filament 28. That is, as shown in FIG. 4, the electron emitter 30 is made of nickel (Ni) with a substantially circular main surface 31 formed at the center and rectangular support sections 32 at both ends.
A base metal plate mainly composed of is bent as shown in FIG. After that, welding is performed at the welding point ₃₂₁ . Next, (Ba, Sr,
Ca) depositing an electron emitting material layer 33 made of CO ₃ ;
This will be activated in a later process. In relation to the filament 28, the width of the rectangular support portion 32 described above is desirably formed so as to reduce heat capacity by shortening the image output time when used in a cathode ray tube or the like. Furthermore, the reason why the filament 28 is held from both sides in the width direction is to make the distortion uniform on both sides when the filament is heated. In addition, compared to this welding method, when the base metal plate is welded only to one main surface of the filament as shown in Figure 1, welding scratches are more likely to be formed on the filament due to the current applied during welding, and the filament will be damaged due to the welding scratches when the current is applied. There is a risk of cutting, and care must be taken to weld within a range that does not cause welding scratches.
In the structure of the present invention, even if welding flaws occur, the welding flaws occur on the base metal plate, so welding flaws do not occur directly on the filament 28. The filament 28 on which the electron emitter 30 as described above is placed and fixed is attached to the first support 22 as described above.
and the second support body 23, but in this case, during assembly, the electron emitter 30 is assembled in a positional relationship in which the center is slightly shifted toward the spring member 29 from the positioning opening ₂₁₂ . There is. This is because when a current is applied to the filament 28 through the first and second supports 22 and 23 and the filament 28 is heated, the filament 28 thermally expands and moves along the broken line along with the spring member 29 on a plane perpendicular to the electron gun axis Z. This is because it is desirable to move to the positions shown at 28' and 29' so that the center is exactly on the center of the positioning opening 21 ₂ , that is, on the electron gun axis Z. Next, a means for attaching the directly heated cathode assembly 20 of this embodiment to three electron guns arranged in a row inside a color picture tube, for example, will be explained with reference to FIG. That is, a row of electron beam passing holes R are arranged in a pair of insulating support rods 41 made of bead glass or the like.
The first grid electrode 42 with holes G and B is attached to the implanted part 4
It is implanted through 3. In addition, other grid electrodes (not shown) are also implanted through the implantation portions, respectively.
Further, a plate-shaped cathode support band 44 is also implanted in each of the insulating support rods 41 via a planting part 45, and a cylindrical cathode support 46 is fixed to this cathode support band 44. Next, the directly heated cathode assembly 20 shown in FIGS. 2 and 3 is inserted into the cathode support 46 described above, and the first grid electrode 4 is inserted as in the case of the conventional indirectly heated cathode assembly.
The electron emitting material layer 33 of the electron emitting body 30 provided opposite thereto through the electron beam passage holes R, G, and B of No. 2
Measure the distance from the top surface using an air micrometer. In this case, since the thin width direction of the filament 28 is attached parallel to the electron gun axis, the strength in the electron gun axis direction is strong, and there is almost no displacement of the filament when it receives the air pressure of the air micrometer. Therefore, measurement errors during and after measurement are extremely unlikely to occur. Next, the cathode tube 26 of the directly heated cathode assembly 20 and the cathode support 46 are fixed by welding to complete an integrated three-electron gun arranged in a row. Next, another embodiment of the present invention will be explained with reference to FIG. In the drawings, the same reference numerals as in the previous embodiment indicate the same parts. The directly heated cathode assembly 40 of this embodiment includes an insulating support plate 21, a first filament support 22, and a second filament support 22.
A filament support 23 is installed in an oblique direction, a filament 28 is installed on the filament support 23, and an electron emitter 30 is placed and fixed thereon. The spring member 29 is provided on the spring support body 24 in the same way as in the previous embodiment, and the free end of the spring member 29 and the filament 2
The elastic contact point 41 with the 8 side surfaces can be moved slightly. By doing so, the directly heated cathode assembly can be made smaller. Next, a third embodiment of the present invention will be described with reference to FIG. That is, the directly heated cathode assembly 5 of this embodiment
0 is a first filament support 22 and a second filament support 23 implanted in an insulating support plate 21
is provided in the longitudinal direction of the insulating support plate 21, and the electron emitter 30 , which is placed and fixed approximately in the center of the filament 28, is assembled from the beginning so as to be centered in the positioning opening ₂₁₂ . Two spring members 29 ₁ and 29 ₂ which come into elastic contact with the sides of the filament 28 are respectively supported by spring supports 24 ₁ and 24 ₂ installed on opposite sides of the filament. In this way, by providing the spring member and the elastic contact portion almost point-symmetrically with respect to the center of the cathode, the number of spring members increases, but the electron emitter 30 always remains in the positioning opening 21 regardless of whether or not the filament is heated.
It has the advantage that it coincides with the center of ₂ and hardly moves. Next, a fourth embodiment of the present invention will be explained with reference to FIG. That is, the directly heated cathode assembly 60 of this embodiment is substantially the same as that of the third embodiment, except that the spring member 2
It is possible to shorten 9 ₁ and 29 ₂ and reduce material costs. Next, a fifth embodiment of the present invention will be explained with reference to FIG. That is, in the directly heated cathode assembly 70 of this embodiment, no particular spring support is provided, and for example, as shown in the figure, the spring member 29 is fixed to the second support 23 at the same part as the filament 28 or separately above and below. This is what I did. In this case, the spring member 29 and the filament 2
It is desirable that a metal oxide film, an insulating member, or the like be interposed at the elastic contact point 71 of No. 8 to prevent current from flowing through the spring member 29. By adopting such a structure, the process can be simplified and the number of parts can be reduced. Next, a sixth embodiment of the present invention will be described with reference to FIG. That is, the directly heated cathode assembly 80 of this embodiment is almost a hybrid of the third embodiment (FIG. 10) and the fourth embodiment, and generally has the effects of adding those of these two embodiments. In this embodiment as well, it is desirable to interpose an insulating member or the like at the elastic contact points 81 and 82 between the spring members 29 ₁ and 29 ₂ and the filament 28, as in the fifth embodiment. Next, a seventh embodiment of the present invention will be described with reference to FIG. 13. That is, the directly heated cathode assembly 90 of this embodiment has the spring members 29 ₁ and 29 ₂ of the sixth embodiment.
, and in this case also the spring member 29
Elastic contact points 91, 9 between ₁ , 29 ₂ and the filament 28
It is desirable that an insulating material be interposed in 2. Next, an eighth embodiment of the present invention will be described with reference to FIG. That is, the directly heated cathode assembly 100 has one end 101 of the spring member fixed to the cathode cylinder 26 by a welding point 102, and the position of the free end of the spring member 29 in elastic contact with the filament 28 is approximately the same as in the other embodiments. The same is true. Next, a ninth embodiment of the present invention will be described with reference to FIG. 15. That is, the directly heated cathode assembly 110 includes a second filament support 111 provided at the rising portion of the cathode cylinder 26,
A filament 28 is installed between the first support 22 and the second support 111. This structure is also simple, but in order to take into account the electrical resistance of the second support 111, a slightly thick conductive member is placed along the cathode tube 26 in the recess of the insulating support plate 21, similar to the second support 3 of the conventional example. It is preferable to plant the tube by a method or to fix it along the cathode tube by welding or the like. As explained above, the present invention consists of a pair of filament supports made of a conductor installed on an insulating support plate, a ribbon-shaped filament installed between the filament supports with the width direction parallel to the electron gun axis, and A base metal plate of the electron emitter that is fixed to the center of the filament and has a main surface part perpendicular to the axis, and a free end part that is fixed to the filament support or another spring support implanted in the insulating support plate. is a directly heated cathode structure having at least one spring member that comes into elastic contact with the side surface of the filament and pushes the filament in a direction perpendicular to the axis. As a result, the width direction of the thin filament is parallel to the electron gun axis, and the filament is always pushed in a direction perpendicular to the electron gun axis, so that the electron emitter is attached to the insulating support plate regardless of whether the filament is heated or not. The height dimension of the electron emitter hardly changes, the cutoff does not change in cathode ray tubes, etc., and the position of the electron emitter only changes in a certain direction pushed by the spring member, or hardly changes in position. Furthermore, even if the sliding properties of the contact area between the filament and the spring member are insufficient, there is little risk that the electron emitter will bounce in the axial direction when the filament expands and contracts, and the electron beam modulation degree will change instantaneously. There is no risk of it getting lost. The free end of the spring member, which has a width larger than that of the ribbon-shaped filament, is in line contact with the side surface of the filament parallel to the electron gun axis and is pushed in a direction perpendicular to the axis. always keeps its width parallel to the electron gun axis. Therefore, the electron emitter is always held perpendicular to the electron gun axis despite its own weight and the filament's thermal expansion and contraction. As described above, the present invention has excellent practical effects.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of a conventional directly heated composite cathode structure, FIGS. 2 and 3 are views showing a first embodiment of the directly heated cathode structure of the present invention, and FIG. Plan view, Figure 3 is a partially cutaway front view, Figures 4 to 6 are
The figures show the structure of the cathode. Figure 4 is a developed view of the base metal plate, Figure 5 a is a front view showing the structure with the parts shown in Figure 4 bent, and Figure 5 b is the front view. Fig. 5c is a side view of the same, Fig. 6a is a front view showing the bent base metal plate as shown in Fig. 5 fixed to hold the filament, and Fig. 6b is a side view of the same. 7 are explanatory diagrams showing the state in which the directly heated cathode structure shown in FIGS. 2 and 3 are assembled into an integrated structure electron gun, and FIGS. 8 to 15 are respectively the direct heated cathode structures of the present invention. FIG. 7 is a plan view showing other embodiments of the cathode structure. 21... Insulating support plate, 21 ₂ ... Positioning opening, 22, 23, 111... Filament support, 24, 24 ₁ , 24 ₂ ... Spring support, 28,
28'... Ribbon filament, 29, 29',
29 ₁ , 29 ₂ ... Spring member, 30 ... Electron emitter, 8, 31, 32 ... Base metal plate, 9, 33 ...
...Electron emitting material layer, Z...electron gun axis.

Claims (1)

[Claims for Utility Model Registration] A pair of conductive filament supports disposed opposite to each other on an insulating support plate; a ribbon-shaped filament installed between the filament supports with the width direction parallel to the electron gun axis; a base metal plate fixed approximately at the center of a ribbon-shaped filament and having a main surface perpendicular to the electron gun axis and having an electron emitting material layer adhered to the main surface, and one end of which is fixed to the filament support or the insulating support plate; The free end portion, which has a width larger than the width of the ribbon-shaped filament, is in line contact with the side surface of the filament in parallel with the electron gun axis, and the filament is moved against the electron gun axis. and at least one spring member for pushing in a vertical direction.