JPS6041822B2 - Post-acceleration cathode ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a post-acceleration cathode ray tube, and more particularly to a post-acceleration cathode ray tube having a structure in which mesh electrodes are removed.

As a post-acceleration cathode ray tube of this type, the patent application
-127951, as disclosed in Japanese Patent Application No. 53-127952, an electron gun, a deflection system for deflecting the electron beam emitted from the electron gun, and at least one post-acceleration provided after the deflection system. It is configured to include at least an electrode, a substantially flat cylindrical electron lens disposed near the latter-stage accelerating electrode, and a target for impacting the electron beam emitted from the electron gun.

Moreover, the electron lens is divided into at least two parts, and the target-side opening has a slit with a width that allows the electron beam to pass through. Therefore, the electron lens reverses the electron beam deflected in the first direction by the deflection system by the lens action inside the cylinder, and converts the electron beam deflected in the second direction perpendicular thereto. is expanded. The pattern, linearity, and spot-like properties are ensured by the combined action of the rear-stage accelerating electrode and the lens (hereinafter referred to as slit lens) formed by the slit section. Therefore, depending on how the post-acceleration cathode ray tube is used, it may be necessary to increase the final acceleration voltage, for example. There are also cases where the size of the tube surface is changed (for example, from 6 inches to 7 inches). In either case, there will be a difference in the influence exerted on the slit portion on the rear accelerating electrode side, and the strength of the slit lens will change. How the pattern and linearity are affected by changing the strength of the slit and lens will be specifically explained below using an example of changing the post-acceleration voltage. FIG. 1 is a schematic diagram of a post-acceleration type cathode ray tube to which the present invention is applied, and is an embodiment disclosed in Japanese Patent Application No. 127951/1983. This consists of an electron gun (an electrostatic focusing electron gun consisting of a cathode 2, first and second grids 3, 4, and first and second anodes 5, 6) and a deflector that deflects the electron beam emitted from the electron gun. a system (consisting of a vertical deflection plate 7 and a horizontal deflection plate 8), at least one post-acceleration electrode provided after the deflection system, and a fluorescent display that bombards the electron beam emitted from the electron gun. It is configured to include at least a target 11 as a screen and a substantially flat cylindrical electron lens disposed between the deflection system and the target. Specifically, the cylindrical electronic lens is a three-part fan-shaped box-shaped electronic lens 9 as shown in FIG. It consists of a combination of 14. Each electrode is vertically and horizontally symmetrical. The upper and lower surfaces of the second cylindrical electrode 13 are each curved convexly toward the cathode 2 side and the target 11 side, and the left and right surfaces are concavely curved, respectively. First cylindrical electrode 12 and third cylindrical electrode 14
The surface in contact with the second cylindrical electrode 13 has a shape corresponding to this. Target 11 of third cylindrical electrode 14
On the side, there is a surface having a slit 27 (hereinafter referred to as slit surface 28).
). With this configuration, for example -2 at cathode 2
．． -1300V is applied to the 0V1 second cylindrical electrode 13 of the 5kV1 second grid 4 and the first and third cylindrical electrodes 12 and 14 of the three-part fan-shaped box-shaped electronic lens 9 to form the second accelerating electrode. When changing the voltage of 10 (A=12.5kv,
B=15.0kV. ．． A characteristic diagram of the change in linearity of C=17.5kv) is shown in FIG. As can be seen from FIG. 3, in both directions, as the post-acceleration voltage is increased, the linearity changes from a positive trend to a negative trend. Fourth
The figure shows a characteristic diagram of changes in pattern distortion when changing the post-acceleration voltage. As you can see from this, as you increase the rear acceleration voltage, the difference between left and right! The vertical bright line does not change at all, but the horizontal bright line changes from a pincushion distortion tendency to a barrel distortion tendency in the upper and lower directions. That is, in this case, the three-part shape of the fan-shaped box lens 9 is determined so that an optimal pattern and linearity can be obtained when the post-acceleration voltage is 15 kV. Therefore, the second stage acceleration voltage is set to, for example, 12.
When operated at 5 kV or 17.5 kV, the strength of the slit lens changes because the strength of the electric field applied to the slit portion changes. This is because even if the post-acceleration voltage remains the same, if the tube surface changes to 5 inches, 6 inches, or 7 inches, the funnel shape of the bulb will change, and the strength of the slit lens will change as described above. In such a case, it has conventionally been necessary to modify the divided shape of the fan-shaped box lens 9 to ensure the pattern and straight line.

In addition, this shape modification requires the creation of many different types of new modification parts, which poses the problem of requiring much effort, time, and cost. The present invention provides an electron gun, a deflection system for deflecting an electron beam emitted from the electron gun, at least one post-acceleration electrode provided at a stage subsequent to the deflection system, and an electron gun emitted from the electron gun. a target to be bombarded with the beam; and a cylindrical shape that is disposed between the target and the deflection system and has substantially first, second, third, and fourth surfaces and is capable of passing the electron beam. at least one first electrode,
a cylindrical portion adjacent to the first electrode and disposed between the first electrode and the target and having substantially first, second, third, and fourth surfaces; a second electrode having a fifth surface that substantially closes a target-side opening of the second electrode with a slit having a width that allows passage of the electron beam; A post-acceleration cathode ray tube characterized in that at least a pair of opposing ends of the fifth surface of the electrode are provided to protrude from the cylindrical part of the second electrode to improve pattern distortion and linearity. This is what we provide. A detailed description will be given below based on the drawings.

FIG. 5 shows a cylindrical electrode 14 having a slit surface 28 facing the target according to the first embodiment of the present invention, and the left and right ends 29, 29'' of the slit surface 28 are connected to the cylindrical shape of the cylindrical electrode 14. It is configured to protrude from the section.

FIG. 6 shows horizontal equipotential lines and a beam trajectory diagram of the slit surface 28. Since the present invention has the configuration shown in FIG. 5, the horizontal potential distribution at the slit 27 is The electron beam swung horizontally as shown by the broken line in Figure 6 is smaller than the conventional one, and as a result, the horizontal linearity is reduced without affecting the vertical linearity or pattern. It can be carried along with the trend. Therefore, it is clear that by shortening the left and right ends of the slit surface, the horizontal linearity can be made to have a positive tendency. FIG. 7 shows a cylindrical electrode 14 having a slit surface 28 according to a second embodiment of the present invention. Similarly, the upper and lower ends 3 of the slit surface 28
By increasing the length of 0.3' in the vertical direction, the vertical linearity can be made to have a negative tendency by about 1 to 2% without affecting the horizontal linearity or pattern. FIG. 8 shows a slit surface of a third embodiment of the present invention in which the same effect as in FIG. 6 is achieved by providing ears 31, 3'' at the left and right ends 29, 29'' of the slit surface. 28. In this case, the linearity can be improved more markedly than the slit surface 28 shown in FIG.
Experimental results show that when the left and right ends 29, 29'' of the slit surface 28 are lengthened from 2 TWL to 5 TWL, the linearity in the horizontal direction becomes negative by about 2 to 4%;
7 to 10 by omitting 1,3" or providing 0.5 order
% is also negative. On the other hand, if the left and right end portions 29, 29'' are shortened, it goes without saying that the linearity in the horizontal direction will go in the positive direction. It has the advantage that pattern distortion and linearity can be easily improved by simply changing the shape of the slit surface of the cylindrical electrode.Furthermore, even when changing the dimensions of the tube surface of the cathode ray tube, the shape of the slit surface of the cylindrical electrode is changed. Since only the following steps are required, it is possible to provide a wide variety of post-acceleration cathode ray tubes in an extremely economical manner.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a post-acceleration cathode ray tube to which the present invention is applied, Fig. 2 is an example of a fan-shaped box type electron lens, Fig. 3 is a linearity characteristic diagram with respect to changes in post-acceleration voltage, and Fig. 4 is A diagram of pattern distortion characteristics with respect to changes in post-acceleration voltage, Figure 5 is a cylindrical electrode according to an embodiment of the present invention, Figure 6 is a horizontal equipotential line and beam trajectory diagram of the slit surface, and Figure 7 is a diagram of the present invention. FIG. 8 shows a cylindrical electrode according to still another embodiment of the present invention. 14... Cylindrical electrode, 27... Slit, 28
...Slit surface, 29, 29'', 30, 3''...
...Slit surface end, 31,3" ...ear.

Claims (1)

[Scope of Claims] 1. An electron gun, a deflection system that deflects an electron beam emitted from the electron gun, at least one post-acceleration electrode provided after the deflection system, and an electron beam emitted from the electron gun. a cylindrical target disposed between the target and the deflection system, having substantially first, second, third, and fourth surfaces, through which the electron beam can pass; at least one first electrode formed in the target; and substantially first, second, third, and third electrodes disposed adjacent to the first electrode and between the first electrode and the target. a second electrode comprising a cylindrical portion having four surfaces and a fifth surface that substantially closes the target-side opening of the cylindrical portion with a slit having a width that allows passage of the electron beam; In the post-acceleration cathode ray tube, at least a pair of opposing ends of the fifth surface of the second electrode are provided to protrude from the cylindrical portion of the second electrode, and pattern distortion and linearity are prevented. A post-acceleration cathode ray tube characterized by improvements. 2. The post-acceleration cathode ray tube according to claim 1, wherein ears are provided at the ends of at least one pair of opposing fifth surfaces protruding from the cylindrical portion of the second electrode.