JPH0135464B2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a cathode ray tube (CRT) for use in oscilloscopes, storage oscilloscopes, etc.
More specifically, the present invention relates to a meshless cathode ray tube having a structure in which a mesh electrode is removed.

Prior Art A conventional post-acceleration cathode ray tube deflects the electron beam emitted from an electron gun vertically or horizontally, and then deflects it by a post-acceleration electric field formed by a flat or curved mesh and a post-acceleration electrode on the inner wall of the bulb. The device is configured to obtain a spot of increased brightness on the luminescent screen by accelerating the spot. However, this type of cathode ray tube has the disadvantages that the spot resolution and electron gun efficiency are deteriorated due to the mesh, and that halation occurs on the screen surface due to secondary electrons emitted by the mesh.

A cathode ray tube that does not use a mesh to solve this kind of drawback is, for example, a box-shaped scanning magnifying lens disclosed in Japanese Patent Publication No. 57-25942, invented by Odenthal. However, in this type of cathode ray tube, the lens has a total length of 10.6 cm, a width of 6.3 cm, and a height of 2.5 cm.
cm and is much larger than the dome mesh method, so conventional glass bulbs cannot be used.
Furthermore, when used in a post-acceleration cathode ray tube, the exit electrode of the lens is electrically connected to the screen potential, so there are drawbacks such as difficulty in maintaining the withstand voltage between the intermediate voltage and other electrodes. Ta.

Furthermore, there is a fan-shaped box-shaped lens disclosed in Japanese Patent Publication No. 58-8543 filed by the present applicant. This is 3
A box-slit lens consisting of a lens produced based on the divided fan-shaped box (hereinafter referred to as the first lens) and a lens produced based on the slit on the target side surface of this box (hereinafter referred to as the second lens). It has a lens, and the interaction between the first lens and the second lens enables display with less vertical blur. However, in this method, the intermediate electrode of the fan-shaped box-shaped lens divided into three parts is convex or concave in both the cathode and target directions, so the equivalent lens center of the first lens (approximately near the center of the intermediate electrode) is There is a limit to how close the cathode ray tube can be to the second lens, and therefore it is difficult to expand the effective area (particularly in the vertical direction) without increasing the overall length of the cathode ray tube.

Further, Japanese Patent Application Laid-Open No. 55-53858, filed by the applicant of the present invention, discloses a fan-shaped box-shaped lens which is divided into two parts. However, although this method allows the effective area to be expanded, there is only one electrode that can be adjusted because it is divided into two parts. There was a drawback that it was difficult to adjust. In addition, in order to prevent the subsequent acceleration electric field from entering the approximately 1 mm gap provided between each electrode for insulation, the box, slit, and lens surroundings of the former 3-split type and the latter 2-split type are shielded. It was inconvenient because it had to be surrounded by electrodes. In addition, a beading method or the like was required to shield and maintain the space between the electrodes, which took a considerable amount of time to manufacture.

OBJECTS OF THE INVENTION Therefore, an object of the present invention is to provide a meshless cathode ray tube that can be downsized and easily manufactured.

Structure of the Invention To achieve the above object, the present invention includes an electron gun and a deflector for deflecting an electron beam emitted from the electron gun in a first direction and a second direction perpendicular to the first direction. at least one back-stage electrode provided after the deflection system, a target for impacting the electron beam emitted from the electron gun, and an electron lens disposed near the back-stage electrode. In the meshless cathode ray tube, the electron lens has a first cylindrical electrode having a substantially rectangular cross-sectional shape and formed flat, and a first cylindrical electrode having a flat substantially rectangular cross-sectional shape a second cylindrical electrode disposed so as to wrap around at least the end of the electrode on the target side; 3 and a fourth surface, and is arranged such that the pair of long sides of the rectangle extends in the second direction and the pair of short sides of the rectangle extends in the first direction, and the first cylinder The ends of the first and third surfaces of the cylindrical electrode on the target side are formed into concave or convex shapes with curvature, and the ends of the second and fourth surfaces of the first cylindrical electrode on the target side are formed in a concave or convex shape with curvature. is formed in a convex or concave shape with a curvature, and the second cylindrical electrode has first and second main surfaces, first and second side surfaces arranged so as to have a substantially rectangular cross section, and and an end face that has a slit to close the end on the target side, and the pair of long sides of the rectangle are opposite to the second end.
The pair of short sides of the rectangle extend in the first direction, the slit is longitudinally formed to extend in the second direction, and the first cylindrical electrode extends in the second direction. The second cylindrical electrode is positioned such that the electron beam passes through the slit after passing through the first cylindrical electrode, and the second cylindrical electrode is positioned such that the electron beam passes through the slit. A lens action is caused in the slit to focus the electron beam in a first direction, and the traveling direction of the electron beam swung in the first direction by the deflection system is reversed and deflected within the second cylindrical electrode. The first and the second The present invention relates to a meshless cathode ray tube characterized in that a voltage supply means for supplying voltage to the cylindrical electrode and the subsequent electrode is provided.

Effects of the Invention According to the above invention, since the second cylindrical electrode surrounds the first cylindrical electrode, it serves as a shield for the first cylindrical electrode, and also serves as a shield for the first cylindrical electrode. It plays the role of creating an electron lens through its interaction with the electrodes. Therefore, there is no need to provide a special shield member, and the configuration is simplified. Further, since the electronic lens is simply constructed by arranging the first cylindrical electrode within the second cylindrical electrode, desired assembly precision can be easily obtained. Additionally, compared to conventional box-slit lenses, it is possible to bring the inversion position of the electron beam in the first direction (vertical direction) closer to the slit, reducing the length of the electron lens and the total length of the CRT. It can be done. Furthermore, it becomes possible to improve deflection sensitivity. Also,
The electronic lens effect based on the slit can prevent vertical blurring of the spot.

Embodiment As shown in FIG. 1, a post-acceleration cathode ray tube according to a first embodiment of the present invention has a cursor 2, a first grid 3, a second grid 4, a first anode 5, and a second anode within a vacuum outer wall 1. 6, and a deflection system 7a consisting of a vertical deflection plate 7 and a horizontal deflection plate 8.
, a cylindrical electron lens 9, a post-acceleration electrode 10, and a target 11 as a fluorescent display screen. An electron gun 2a that emits an electron beam, and a deflection system 7 that deflects the electron beam in a first direction (vertical direction) and a second direction (horizontal direction) orthogonal thereto.
a, the latter-stage accelerating electrode 10 that applies an accelerating electric field, and the target 11 that is bombarded by the electron beam are known parts, and the electron lens 9 is the part related to the present invention.

As is clear from FIGS. 1 to 4, the electron lens 9 according to the present invention includes a first cylindrical electrode 12 made of a small cylinder with a substantially rectangular cross section, and a cross section surrounding the first cylindrical electrode 12. The second cylindrical electrode 13 is a large cylinder having a substantially rectangular shape. As is clear from FIGS. 5 to 8, the first cylindrical electrode 12 has first, second, third and fourth surfaces 15, 16, 1
7 and 18, and is formed so that the electron beam enters from the opening at the left end in FIG. 2 and passes through the opening at the right end. Note that the first and third surfaces 15 and 17 facing each other extend in the second direction (horizontal direction), and the second and fourth surfaces 16 and 18 facing each other extend in the first direction (vertical direction). ). Further, the ends 23 on the target side of the first and third surfaces 15 and 17 have a curvature like a part of a circle, a part of an ellipse, or a part of a hyperbola, and are each curved concavely in the direction of the electron gun. are doing. Furthermore, the ends 24 of the second and fourth surfaces 16 and 18 on the target side each have a curvature like a part of a circle, a part of an ellipse, or a part of a hyperbola, and protrude convexly in the direction of the target. ing.

A second cylindrical electrode 13 surrounding the first cylindrical electrode 12
As is clear from FIGS. 9 to 12, the first main surface 19 extends in the second direction (horizontal direction);
A second main surface 21 opposite to this first main surface 19
A first side surface 20 extending in a first direction (vertical direction), a second side surface 22 opposite to this first side surface 20, and a slit 27 closing the end on the target side. It consists of an end plate or end face 14. The ends of the first and second main surfaces 19 and 21 on the target side have a curvature like a part of a circle, a part of an ellipse, or a part of a hyperbola, as shown in FIGS. It protrudes convexly on the side. However, the ends of the first and second side surfaces 20, 22 on the target side are straight lines, as is clear from FIG. As is clear from FIG. 11, the slit 27 in the end face 14 extends in the second direction (horizontal direction).

As is clear from FIG. 3, the positional relationship between the first cylindrical electrode 12 and the second cylindrical electrode 13 is that the first and third surfaces 15, 17 of the first cylindrical electrode 12 and the second
The first and second main surfaces 19, 21 of the cylindrical electrode 13
Equal gaps 28 are created between the second and fourth surfaces 16, 18 of the first cylindrical electrode 12 and the first and second side surfaces 20, 2 of the second cylindrical electrode 13, respectively.
The setting is such that an equal gap 29 is created between the two. In short, the first cylindrical electrode 1
2 is arranged at the center of the cross section of the second cylindrical electrode 13. Target side end 2 of first cylindrical electrode 12
3 and 24 are located closer to the electron gun than the end 25 of the second cylindrical electrode 13 on the target side, and are surrounded by the second cylindrical electrode 13.

The electron lens 9 consisting of the first and second cylindrical electrodes 12 and 13 is configured such that an undeflected electron beam is directed to the CRT shown in FIG.
13 and the center of the slit 27.

In order to configure an electron lens by the first and second cylindrical electrodes 12 and 13, for example, a terminal 41 for supplying 0 volts (kV with respect to the cathode) to the first cylindrical electrode 12 is connected to a voltage The second cylindrical electrode 13 is provided as a supply means, and the second cylindrical electrode 13 is, for example, −1000 to −
A terminal 42 for supplying 1300V (700 to 1000V to the cursor) is provided as voltage supply means. Further, in order to form a lens near the slit 27, the end surface 14 of the second cylindrical electrode 13 on the target side is arranged near the rear-stage accelerating electrode 10.

Has a display screen of 8cm in height and 10cm in width.
To illustrate the geometric dimensions of the first and second electrodes 12 and 13 of a CRT, the height of the first electrode 12 is approximately
10mm, width approximately 24mm, first and third surfaces 15, 17
From the end (inlet) of the electron gun to the end 23 on the target side
The length from the electron gun side end (inlet) of the second and fourth surfaces 16, 18 to the curved apex of the target side end 24 is about 24 mm.
The radius of curvature of the end 23 is approximately 20 mm, the radius of curvature of the end 24 is approximately 6 mm, and the height of the second cylindrical electrode 13 is approximately 14 mm.
mm, width approximately 36 mm, first and second main surfaces 19, 21
from the electron gun side end (inlet) to the target side end 2
The length from the end of the first and second side surfaces 20 and 22 on the electron gun side to the end 26 on the target side is approximately 29 mm, and the radius of curvature of the end 25 is approximately 33 mm. The height of the slit 27 on the end face 14 along this curvature is approximately 5 mm, and the width is approximately 46 mm along the curve.
It is 30mm. In addition, the first electrode 12 and the second electrode 1
The gaps 28 and 29 between 3 are each about 1.5 mm, about
It is 5.5mm. These electrodes 12, 13 have a thickness of 0.5
mm of non-magnetic stainless steel. However, only the end surface 14 of the second cylindrical electrode 13 has a thickness of 0.3 mm.
Made of non-magnetic stainless steel.

Next, the function of the electronic lens 9 according to the present invention will be described in a first manner.
This will be explained with reference to FIGS. 3 to 16. If an electron lens is constructed by applying a voltage of, for example, 0 V to the first cylindrical electrode 12 and a voltage of, for example, -1200 V to the second cylindrical electrode 13, the vertical direction (first direction) as shown in FIG. swung electron beam 30 or electron beam 3
1 is the second cylindrical electrode 1 without advancing as shown by the dotted line.
3 and moves in the direction shown by the solid line, passing through the slit 27 and reaching the target 11. Further, as shown in FIG. 14, the electron beam 32 or electron beam 33 swung in the horizontal direction (second direction) does not travel straight as shown by the dotted line, but the deflection angle is expanded and it advances in the direction shown by the solid line and reaches the slit 27. It reaches the target 11 through. The lens effect as described above is obtained by a kind of quadrupole lens effect occurring between the inner part of the second cylindrical electrode 13 and the curved ends 23 and 24 of the first cylindrical electrode 12. .

By the way, when a voltage of, for example, 12 kV is applied to the second stage accelerating electrode 10, since the voltage at the end face 14 is -1200 V, a high electric field enters the vicinity of the slit 27, and an electron lens (hereinafter referred to as a slit lens) is formed. The horizontal potential distribution in this slit lens has almost no effect on the electron beams 34, 35, as shown by equipotential lines 39 in FIG. Therefore, the focused electron beams 34, 35
is focused on target 11. On the other hand, the vertical potential distribution in the slit lens is as shown by equipotential lines 40 in FIG. 16, and a convex lens is formed near the slit 27. For this reason, the focused electron beam is once focused within the second cylindrical electrode 13, and when it starts to diverge, it is focused on the target 11 by the convex lens action of the slit lens. In this case, the on-axis electron beam 3
The convex lens effect acts strongly on the electron beam 6, and the convex lens effect acts weakly on the electron beam 37 that travels toward the slit 27 from above and the electron beam that travels toward the slit 27 from the bottom (not shown).
If there is no convex lens effect due to the slit 27, if the focus voltage is adjusted so that the focus is centered on the screen, the electron beam will be at the 16th
The electron beam 37 is focused on a dotted line 38 in the figure, and is overfocused, causing blurring at the top and bottom of the screen. Therefore, this slit 27 has an important role of correcting focus blurring at the top and bottom of the screen.

The electron beam deflected in the horizontal direction by the horizontal deflection plate 8 is further deflected and expanded between the first cylindrical electrode 12 and the second cylindrical electrode 13, and then passes through the slit 2 having a curvature.
Enter 7. If you change the curvature of this slit 27,
The horizontal deflection rate changes. Therefore, by changing the curvature of the slit, the horizontal deflection rate can be adjusted, and the horizontal deflection of the electron lens generated between the first cylindrical electrode 12 and the second cylindrical electrode 13 can be adjusted. Even if the direct linearity tends to be positive, it can be corrected to some extent by correspondingly weakening the curvature, and conversely, if there is a negative tendency, it can be corrected to some extent by correspondingly increasing the curvature. This is a great design advantage.

When designing this device, the dimensions of the first cylindrical electrode 12 and the second cylindrical electrode 13 are determined based on the total length of the cathode ray tube, the tube surface effective area, and the sensitivity in horizontal and vertical directions. The ends 23, 24 of the first cylindrical electrode 12 and the second
The radius of curvature of the end 25 of the second cylindrical electrode 13 and the distance from the electron gun side opening of the second cylindrical electrode 13 to the apex of the curved portion of the end 25 on the target side are determined. This will be explained in detail below.

First, a first cylindrical electrode 12 and a second cylindrical electrode 13
The electron lens formed between the first cylindrical electrode 12
An explanation will be given of how a change in the radius of curvature of the edges 23 and 24 affects the tendency of pattern distortion. When the radius of curvature of the end portion 24 of the first cylindrical electrode 12 is decreased from, for example, 6 mm to 5.5 mm, the vertical bright line tends to cause barrel distortion, and the horizontal bright line tends to cause pink tension distortion. Further, when the radius of curvature of the end portion 23 of the first cylindrical electrode 12 is decreased from, for example, 20 mm to 17 mm, the vertical bright line tends to cause pincushion distortion, and the horizontal bright line tends to cause barrel distortion. Furthermore, the fact that the direction in which the radius of curvature is made smaller is the direction in which the deflection ratio is improved in both cases of the two end portions 23 and 24 means that the electron lens between the first cylindrical electrode 12 and the second cylindrical electrode 13 It is clear that this will strengthen the Further, as described above, if the radius of curvature of the end 24 of the first cylindrical electrode 12 is made smaller, the horizontal deflection straightness becomes positive, but in that case, the end 25 of the second cylindrical electrode It is better to increase the radius of curvature, for example from 46 mm to 50 mm.

When the dimensions and radius of curvature of the first cylindrical electrode 12 are determined in this way, the radius of curvature of the end 25 of the second cylindrical electrode 13 and the position of the slit 27 are also determined correspondingly. That is, since the geometrical dimensions between the first cylindrical electrode 12 and the second cylindrical electrode 13 are interdependent, when one is determined, the other is also necessarily determined.

As is clear from the above, the cathode ray tube of this embodiment has the following advantages.

(A) The second cylindrical electrode 13 is the same as the first cylindrical electrode 12.
Since it surrounds the first cylindrical electrode 12, it serves as a shield for the first cylindrical electrode 12, and also serves to create an electron lens in interaction with the first cylindrical electrode 12. Therefore, there is no need to provide a special shield member, and the configuration is simplified.

(B) First cylindrical electrode 1 inside second cylindrical electrode 13
Since the electronic lens 9 is obtained by arranging the lens 2, desired assembly accuracy can be easily obtained.

(C) In the case of the split type electron lens disclosed in Japanese Patent Publication No. 58-8543, it was difficult to bring the vertical reversal position of the electron beam very close to the slit. In contrast, with the electronic lens of this embodiment, it is possible to get much closer. Therefore, the total length of the CRT can be shortened. When compared with the same accelerating voltage, total length of cathode ray tube, electron gun, and deflection system, a significant improvement of 40% in the vertical deflection rate and 25% in the horizontal deflection rate was obtained.

(D) It becomes possible to significantly improve deflection sensitivity.

(E) Since the configuration is such that the quadrupole electron lens generated by the first and second cylindrical electrodes 12 and 13 is corrected by the slit lens generated by the relationship between the slit 27 and the rear acceleration electrode 10, the spot on the target 11 is It is possible to prevent blurring.

Modifications The present invention is not limited to the above-described embodiments, and various modifications, such as the following, are possible.

(a) As shown in FIG. 17, the end 23 of the first cylindrical electrode 12 has a curvature and has a convex shape protruding toward the target side, and the end 24 has a curvature and is curved toward the electron gun side. It may be concave. In this case, if the first cylindrical electrode 12 is set to 0V, the second cylindrical electrode 13 is set to a voltage higher than this, for example +1500~
Set to 2000V.

(b) The slit 27 is formed to improve horizontal bright line pattern distortion or horizontal deflection straightness, as disclosed in Japanese Patent Application Laid-open No. 56-152143.
As shown in FIG. 18 or 19, the slit 2
7 may be curved concavely or convexly. Alternatively, the end surface 14 may be made straight by adjusting the position of the first cylindrical electrode 12 and the radius of curvature of the ends 23 and 24.

(c) In this embodiment, the second grid 4, the first anode 5, the second anode 6 are used as a focusing lens as shown in
Although a cylindrical lens consisting of a cylindrical lens is used, it may also be composed of three sets of quadrupole lenses as shown in FIG. 17 of Japanese Patent Publication No. 58-8543. Further, as shown in FIG. 18 of this publication, a quadrupole lens may be inserted between the vertical deflection plate and the horizontal deflection plate in order to strengthen the deflection expansion in the vertical direction. That is, the first part of this bulletin
The box slit lens in FIGS. 7 and 18 can be replaced with the cylindrical electron lens 9 of the present invention.

(d) In practice, if the second cylindrical electrode 13 wraps around the first cylindrical electrode 12 to such an extent that the subsequent acceleration electric field does not enter the screen side ends 23 and 24 of the first cylindrical electrode 12, Therefore, there is no problem even if the end of the first cylindrical electrode 12 on the electron gun side protrudes from the second cylindrical electrode 13.

(e) Even if the voltage of the second accelerating electrode 10 is set to 0 volts, a lens effect occurs in the slit 27 because -1000 to -1300 V is applied to the second cylindrical electrode 13. Therefore, the present invention can also be applied to storage tubes. For this reason, the latter-stage acceleration electrode 10 can be replaced with, for example, a collimation electrode whose purpose is not to accelerate.

(f) As shown in FIG. 20A, the upper and lower surfaces of the first and second cylindrical electrodes 12 and 13 are formed to widen toward the target, and as shown in FIG. 20B, the first and second cylindrical electrodes 12 and 13 It is also possible to form both side surfaces of the shaped electrodes 12 and 13 to diverge toward the target, or to form upper and lower surfaces and both side surfaces to diverge toward the target as shown in FIG. 20C. Those skilled in the art can easily understand that the effects of the present invention can be obtained even if the tubes of the electrodes 12 and 13 are configured in this manner. In the case of FIG. 20 as well, the end face 14 may be made straight, or the slit 27 may be deformed as shown in FIGS. 18 and 19.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a CRT according to an embodiment of the present invention, FIG. 2 is a perspective view of the electron lens shown in FIG. 1, and FIG.
The figure is a cross-sectional view of the part corresponding to line A-A' in Figure 2,
4 is a longitudinal sectional view of FIG. 2, FIG. 5 is a perspective view of the first cylindrical electrode, and FIG. 6 is a plan view of the electrode of FIG.
Figure 7 is a right side view of the electrode in Figure 5, and Figure 8 is a right side view of the electrode in Figure 5.
FIG. 9 is a perspective view of the second cylindrical electrode, FIG. 10 is a plan view of the electrode in FIG. 9, and FIG.
The figure is a right side view of the electrode in Figure 9, Figure 12 is a front view of the electrode in Figure 9, Figure 13 is a diagram showing the trajectory of the electron beam in the vertical direction of the electron lens, and Figure 14 is a diagram showing the trajectory of the electron beam in the vertical direction of the electron lens. Diagram showing the trajectory of the electron beam in the horizontal direction,
Figure 15 is a horizontal cross-sectional view of the slit part,
6 is a vertical cross-sectional view of the slit portion, FIG. 17 is a perspective view showing another embodiment of the electron lens, and FIG.
This figure and FIG. 19 are front views showing a modification of the slit. 20A, B, and C are perspective views showing modified electronic lenses. 2a...electron gun, 7a...deflection system, 9...electron lens, 10...later acceleration electrode, 11...target (screen), 12...first cylindrical electrode,
13...Second cylindrical electrode, 27...Slit.

Claims (1)

[Scope of Claims] 1. An electron gun; a deflection system that deflects an electron beam emitted from the electron gun in a first direction and a second direction perpendicular to the first direction; A meshless cathode ray tube comprising: at least one rear electrode provided at a rear stage; a target for impacting the electron beam emitted from the electron gun; and an electron lens disposed near the rear electrode. The electron lens includes a first cylindrical electrode having a substantially rectangular cross-section and a flat shape, and at least a target-side end of the first cylindrical electrode having a substantially rectangular cross-section and a flat shape. and a second cylindrical electrode arranged so as to wrap around the electrode, and the first cylindrical electrode has first, second, third and fourth surfaces arranged so as to have a substantially rectangular cross-sectional shape. and arranged such that a pair of long sides of the rectangle extend in the second direction and a pair of short sides of the rectangle extend in the first direction, and the first and second sides of the first cylindrical electrode The target side end of the third surface is formed into a concave or convex shape with curvature, and the target side ends of the second and fourth surfaces of the first cylindrical electrode are formed into a convex shape with curvature. Alternatively, the second cylindrical electrode is formed in a concave shape, and the second cylindrical electrode has first and second main surfaces, first and second side surfaces, and an end on the target side arranged so as to have a substantially rectangular cross-sectional shape. and a closed end face, and is arranged such that the pair of long sides of the rectangle extends in the second direction and the pair of short sides of the rectangle extends in the first direction, and the slit has a closed end face. The first cylindrical electrode is formed in a longitudinal direction so as to extend in a second direction, the first cylindrical electrode is disposed at a position through which the electron beam passes, and the second cylindrical electrode is arranged so that the electron beam passes through the first The electron beam is arranged to pass through the slit after passing through the cylindrical electrode, and causes the slit to produce a lens action that focuses the electron beam in the first direction, and also causes the electron beam to be focused in the first direction by the deflection system. The traveling direction of the swung electron beam is reversed within the second cylindrical electrode to produce an effect of deflecting and expanding the electron beam, and the electron beam swung in the second direction by the deflection system is directed to the second cylindrical electrode. A meshless type characterized in that a voltage supply means is provided for supplying a voltage to the first and second cylindrical electrodes and the latter stage electrode so as to cause an action of deflection and expansion within the second cylindrical electrode. cathode ray tube.