JPH0231720Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a cathode assembly used in a cathode ray tube electron gun, and in particular improves the insulation between the cathodes and the first control electrode, or when a plurality of cathodes are arranged on the same plane. The present invention relates to improvements in cathode structures for the purpose of Figure 1 shows a cathode structure 1 commonly used in the past.
FIG. 3 is a partial cross-sectional view including the first control electrode showing 0;
The cathode cylinder 13, which is a cap-shaped cylinder with a thermionic emissive material layer deposited on the top, is caulked to an insulating stone 11 made of ceramic such as alumina or steatite.
The lower end portion is welded and fixed to the outer cathode support cylinder 12 which is fixed by caulking or the like at 12B. The insulating stone 11 that supported the cathode tube 13 is placed inside the first control electrode 14 which is a bottomed cylindrical shape with a through hole in the closed surface, and the upper surface position of the insulating stone 11 is regulated by a spacer 15, and the lower surface thereof is regulated by a spacer 15. The stator 16 is pressed into contact with the first control electrode 14, and the stator 16 is welded to the side surface of the first control electrode 14 to be supported and fixed. At this time, the height of the spacer 15 is selected so that the difference in distance between the top of the cathode cylinder 13 and the upper surface of the insulating stone 11 with respect to the closed surface of the first control electrode 14 becomes a predetermined value. Normally, a groove 11A surrounding the outer cathode support tube 12 is bored in the upper surface of the insulating stone 11 on the electron emitting surface side of the cathode tube 13. This is the cathode tube 1 during cathode ray tube operation.
The metal Ba that is reduced and produced from the electron emitting surface at the top of the cathode is evaporated by the heat of the heating wire inserted into the cathode cylinder 13 and the first control electrode even if this evaporated substance adheres to the upper surface 11B of the insulating stone 11. In order to prevent the insulation between the cathode 14 from deteriorating, a blind spot is created within the angle from which the groove 11A is viewed from the top of the cathode. However, in the method of forming a blind spot for evaporated matter from the top of the cathode using the groove 11A described above, the deeper the groove 11A is, the more the groove 11A is required to improve the insulation between the cathode tube 13 and the first control electrode 14. The narrower the width, the better, but the thickness of the insulating stone 11 is usually about 1 to 2 mm, and if the width is made too deep, the mechanical strength of the insulating stone will be impaired. This makes it difficult to form the groove when forming the groove, making it impossible to obtain a necessary and sufficient blind spot. In particular, in cathode assemblies used in narrow electron guns for cathode ray tubes, the overall dimensions are reduced, and the annular groove 11A is formed in the insulating stone 11.
There is no dimensional margin to drill the grooves 11A, and it becomes very difficult to process the extrusion mold of the insulating stone 11 that forms the grooves 11A. Furthermore, when pressing the insulating stone 11, it becomes difficult to form the groove, the accuracy is poor, and due to dimensional constraints, an effective blind spot cannot be obtained. The present invention eliminates the above-mentioned drawbacks and provides a structure in which the lower ends of one or more cap-shaped cathode tubes, the top of which is coated with a thermionic emissive material, are welded to each other.
In a cathode assembly equipped with two or more outer cathode support tubes, the bottom surface is provided with an opening that fits into the outer diameter of the outer cathode support tube in the fixed part of the upper surface of the insulating stone facing the top side of the cathode tube. To provide a cathode assembly for a cathode ray tube in which the upper part of an outer cathode support tube is fixed by inserting a dish-like plate having a stepped annular edge a micro distance higher than the bottom surface. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 shows a cathode structure 2 based on an embodiment of the present invention.
FIG. 3 shows a side cross-sectional view including the first control electrode of FIG. . The caulked portion 12A of the outer cathode support tube 12 on the upper surface of the insulating stone 11 facing the top side of the cathode tube 13 is provided with an opening that fits into the outer diameter of the outer cathode support tube 12 as shown in FIG. After inserting the dish-shaped plate 21 having a bottom surface 21A and a stepped annular edge 21B that is slightly higher than the bottom surface, the outer cathode support cylinder 12 is attached to the insulating stone 11 with the caulked edges 12A and 12B as in the conventional case. It is caulked and fixed. In this case, on the upper surface of the insulating stone 11, the outer cathode support tube 12 and the first control electrode 14 are formed by accretion of evaporates from the top of the cathode tube 13, as in the conventional case.
There is no particular need for an annular groove to prevent a decrease in insulation between the two. Cap-shaped cathode tube 1 with a thermionic emissive material layer deposited on the top
3 is welded and fixed at the lower end of the outer cathode support tube 12, and the insulating stone 11 that supports and fixes the cathode tube 13 is the first
A spacer 15 is provided in the control electrode 14 so that its upper surface 1
1B position is regulated, and its lower surface is fixed to the first control electrode 14 by a stator 16. According to the embodiment of the present invention, the outer cathode is placed on the upper surface 11B of the conventional insulating stone 11 in order to prevent insulation deterioration between the outer cathode support tube 12 and the first control electrode 14 due to deposition of evaporated matter from the top of the cathode tube 13. Even if an annular groove is not particularly formed to surround the support tube 12,
The annular edge 21B of the dish plate 21 fixed by the caulked edge 12A provides a sufficient blind spot against evaporative accretion. Here, the annular edge 21B of the dish-shaped plate 21 is located at a position floating about 0.2 to 0.3 mm from the bottom surface 21A, and the width is preferably as large as possible within a range smaller than the inner diameter of the first control electrode 14, but in practice it is 0.5 to 1.5 mm. A certain degree is fine. Therefore, in order to obtain a sufficient blind spot against the accretion of evaporates from the top of the cathode by the annular groove as in the past, it is necessary to make the groove deeper and narrower at the expense of the strength and workability of the insulating stone 11. disappears. Alternatively, even if there is little dimensional margin to form a necessary and sufficient annular groove in the insulating stone 11, especially when the cathode structure 20 is downsized, applying the present invention eliminates the need for an annular groove, so the upper surface shape of the insulating stone 11 is simple. This makes processing the mold and manufacturing extremely easy. In addition, the metal Ba reduced from the top of the cathode tube 13 during operation of the cathode ray tube not only accretes linearly onto the upper surface of the insulating stone 11, but also collides with residual gas molecules in the tube, scatters, and accretes vertically onto the upper surface 11B of the insulating stone 11. However, this embodiment can create sufficient blind spots even for these. Alternatively, as shown in FIG. 4, there is an in-line cathode structure 30 in which three cathodes 13 are arranged in-line in the same plane and fixed to an insulating stone 31.
In this case, evaporated matter from the cathode tubes 13 on both sides is deposited between the center and both outer cathode support tubes 12.
The conventional annular groove surrounding each outer cathode support cylinder 12 did not provide a sufficient blind spot. However, since the outer cathode support cylinder 12 is fixed by inserting the dish-like plates 21 having the annular edges 21B into the upper caulking portions according to the present invention, the insulation between adjacent cathodes does not deteriorate. Furthermore, since the dish-shaped plate 21 made of metal is inserted into the caulking part of the outer cathode support cylinder 12 and caulked, both parts fit together at the caulking edge 12A, and the bottom part 21A of the dish-shaped plate 21 plays the role of an elastic material. As a result, since this is pressed and crimped, the crimping strength is dramatically improved, and the thermal expansion of the outer cathode support cylinder 12 during operation of the cathode ray tube, which causes play in the crimped part over time, is prevented, making it extremely stable. Cathode characteristics can be obtained. In the above description, the case where the annular groove is not formed on the upper surface of the insulating stone 11 has been described, but the annular groove and the present invention may be used together as in the conventional case. If the size of the annular edge 21B is selected so as to cover the annular groove, a more effective shielding effect can be obtained against the deposition of evaporated matter from the top of the cathode.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view including a first control electrode showing a conventionally used cathode structure 10 , FIG. 2 is a sectional view including a first control electrode showing a cathode structure based on an embodiment of the present invention, FIG. 3 is a perspective view of a dish plate with an annular edge according to the present invention, and FIG. 4 is a sectional view of an in-line cathode assembly according to another embodiment of the present invention. 11, 31... Insulating stone, 11A... Annular groove, 1
2... Outer cathode support tube, 13... Cap-shaped cathode tube, 1
4...First control electrode, 15...Spacer, 16...
Stator, 20, 30...Cathode structure, 21...Dish plate.

Claims (1)

[Scope of utility model registration request] In a cathode structure equipped with an outer cathode support tube, in which the lower end of a cap-shaped cathode tube with a thermionic emissive material layer coated on the top is fixed by welding at one end, and the other end is fixed by caulking to a through hole in an insulating stone. , At the top of the cathode cylinder of the insulating stone, a dish-shaped plate connected to a bottom face with a hole that fits into the outer diameter of the outer cathode support cylinder and having an annular edge 0.2 to 0.3 mm higher than the bottom face is attached to the top of the cathode cylinder of the insulating stone. Disposed between the facing surface and the other end of the outer cathode support tube to float the annular edge from the insulating stone, and position the other end caulked portion of the outer cathode support tube on the bottom surface of the dish-shaped plate. A cathode ray tube cathode assembly characterized by: