JPS622436A - Electron tube - Google Patents

Abstract

PURPOSE:To prevent the deterioration in various characteristics such as resolution, figure stain and shading by using a cylindrical deflecting electrode which consists of plural parts apart from each other and located inside the outer tube, a disk-like or circular electrode facing toward a electron gun d a disk-like electrode located near the other end of the cylindrical electrode. CONSTITUTION:An electron beam 2 discharged from an electron gun 1 is focused on the surface of a target 18 by means of a disk-cylinder convex lens which consists of a G2 terminal electrode 65, a deflecting electrode 4 and a mesh electrode group. The electron beam 2 can be deflected while making it perpendicularly incident upon the surface of the target 18 by applying a deflecting voltage to the deflecting electrode 4 in addition to a d.c. voltage. It is desirable that the ratio of the inner diameter (d1) of a glass envelope 10 to the length (l1) of the deflecting electrode 4 be adjusted to 1-3. The distance (lMR) between the mesh electrode 17 and the deflecting-electrode-side end of a ring electrode 19 is adjusted to 0.1d1-0.5d1 (d1, the diameter of the electron tube). Due to the above structure, it is possible to minimize both the strain of the figure and the miss collimation of the beam.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an electric field focusing or electric field deflection type image pickup tube or cathode ray tube in which electron beams are focused and deflected entirely by electric fields.

(Prior art) As one of the focusing and deflecting methods for a scanning electron beam in an image pickup tube, the all-electrostatic type (hereinafter referred to as S
S-type (abbreviated as S-type) is known.

Since the SS type does not require any electromagnetic coil, it is most advantageous for reducing the size, weight, and power consumption of the image pickup tube. However, compared to conventional focusing and deflection methods that use electromagnetic coils for either focusing, deflection, or both, the SS type does not necessarily have the same characteristics as resolution, graphic distortion, and uniformity of signal level within the screen (shading). It had the drawback of not being sufficient.

Here, FIG. 15 shows a conventional SS type focusing/deflecting section.

Cylindrical electrodes 3 arranged in order from the electron gun 1 side. DC voltage Vll+ is applied to the defleftron electrode 41 and the cylindrical electrode 5, respectively.
By adding VL+VI+, the potential distribution shown in FIG. 16 is created in the tube. Furthermore, by applying an appropriate deflection voltage of ν to the four arrow pattern electrodes constituting the defleftron electrode 4, a focusing deflection function is provided. Further, a collimation lens is formed by the cylindrical electrode 5 and the mesh electrode 17 at the rear stage.

(Problems to be Solved by the Invention) As an optimal design condition for the above configuration, the ratio L/D of the diameter of the cylindrical electrode portion and their total length is 2 to 4. If possible, around 3 has been considered the best. This focusing deflection section consists of three cylindrical electrodes (one of which is a defleftron electrode), and the length of these cylindrical groups almost determines the tube length, so it is particularly inferior in terms of miniaturization compared to the one of the present invention described later. There were drawbacks. Furthermore, since the electron lens formed by the cylindrical electrode group includes elements for a concave lens, a strong convex lens cannot be formed, and as mentioned above, it is inferior to the conventional MS type image pickup tube in terms of resolution, graphic distortion, etc.

Furthermore, in order to take out the electrode leads for applying voltage to each of the three cylindrical electrodes, it was necessary to make a hole in the tube wall or to draw them out across other electrodes, which caused problems in the manufacturing process and reliability. Not only is it inferior, but
It had the unavoidable drawback of poor characteristics due to disturbances in the electric field.

(Means for Solving the Problems) An object of the present invention is to eliminate the drawbacks of the above-mentioned known examples, and to improve the conventional focusing/deflection type electron tube using electromagnetic coils for either focusing, deflection, or both. In comparison, especially the resolution,
It is an object of the present invention to provide an all-electrostatic electron tube that is small, lightweight, and consumes little power, without deteriorating physical characteristics such as graphic distortion and shading.

That is, the electron tube of the present invention includes a plurality of divided cylindrical deflection electrodes disposed inside the outer tube of the electron tube, and at least a disk-shaped deflection electrode disposed on the electron gun side of the cylindrical deflection electrode, or when viewed from the tube axis direction. It includes a circular electrode and a disc-shaped electrode disposed at the other end of the cylindrical electrode, and is configured to focus an electric field and deflect an electric field so as to make the second-order differential in the axial direction of the potential distribution on the tube axis positive. It is characterized by comprising a section.

(Embodiment) FIG. 1 shows a first embodiment of the SS type focusing/deflecting unit according to the present invention.

The basic electrode configuration includes an electron gun section 1 that takes out the electron beam, a defleftron electrode 4. Mesh electrode 17. and Targelales 8. The electron gun section 1 shown in FIG. 1 is a so-called triode type example, and the cathode 6
1. Gl electrode 62. G2 electrode 63° Beam limiting hole 64 and G2 electrically and mechanically integrated with G2 electrode 63
It consists of a terminal electrode 65.

Other types of electron gun, such as a laminar flow type electron gun, can also be used. In this electrode configuration, the G2 electrode 63
When a voltage v2 is applied to the deflectron electrode 4, a voltage ν3 is applied to the deflectron electrode 4, and a voltage V is applied to the mesoche electrode 17, the voltage inside the tube is as shown in Fig. 2(a).
A potential distribution as shown in is formed.

φ the axial potential distribution. (Z) CZ is the coordinate in the tube axis direction), and φ. The first derivative of (Z) with respect to 2 is φ. '(Z
), the second derivative is φ. ''(Z), the radial force acting on electrons traveling near the tube axis (hereinafter abbreviated as paraxial electrons) is generally proportional to 1φ.''(Z). Therefore, φ. ′
(2) When ≠0, a lens effect occurs and φ. ′(Z)
If is positive, a convex lens is formed, and if it is negative, a concave lens is formed.

That is, φ. “The positive/negative of (Z) determines the concavity and convexity of the electron lens.

In the electrode configuration shown in the first figure according to the present invention, 62 disk-shaped terminal electrodes 65 are disposed at both ends of the cylindrical defleftron electrode 4. and the potential V2 of the mesh electrode 17. If V is set higher than the potential v3 of the defleftron electrode 4,
φ. #(Z) is always positive as shown in FIG. 3, and the entire space has only a convex lens effect.

FIG. 2(a) shows the potential distribution inside the tube obtained by computer simulation under the condition that only the DC voltage v3 is applied to the defleftron electrode 4 in the embodiment according to the present invention shown in FIG. 7, which will be described later.

Figure 2(b) shows that an electron beam is applied to a target 1 in order to clarify the optical properties of an electron lens using similar means.
This is the result of finding three representative electron orbits under the condition of convergence at 8.

The orbit 71 shown in FIG. 2(b) is the orbit of an electron (abbreviated as β1 orbit) starting from a point one distance away from the tube axis on the G2 terminal electrode 65 (abbreviated as β1 orbit), and the orbit 72 is the orbit on the G2 terminal electrode 65. 65
The orbit of the electron departing from the upper tube axis at an angle of 5 degrees with the axis (hereinafter abbreviated as α orbit), orbit 73 is the target 18
This is an orbit of an electron (hereinafter referred to as a β2 orbit) that starts from the center of the orbit parallel to the axis in the opposite direction to the orbit 71.

The existence of the point 74 where the orbit 71 intersects the axis (hereinafter referred to as the first crossover) means that the convex lens 66 exists between the G2 terminal electrode 65 and the first crossover 74, and its focal point is at the point F1. means to exist. Similarly, the point 7 where the β2 orbit 73 intersects the axis (referred to as the second crossover)
5 means that a convex lens 67 exists between the mesh electrode 17 and the second crossover, and its focal point exists at point F2. Since the point 76 where the α orbit 72 intersects with the axis means the image plane, it coincides with the position of the target 18. Since the above convex lenses 66 and 67 are formed of a disk and a cylinder, they are generally called disk-cylindrical lenses.

Compared to a cylinder-cylindrical lens in which two cylinders are placed side by side, a disk-cylindrical lens has no space to exert a concave lens effect, so there is no spread of electron trajectories within the lens, resulting in aberrations. It also has the advantage that the length of the space that acts as a lens is, in principle, half that of a cylindrical-cylindrical lens.

By the way, if the positions and strengths of the convex lenses 66 and 67 in FIG. 2(b) are appropriately selected, the first
can be imaged onto the target 18 by the second convex lens 67. in this case,
The aberration of the first convex lens 66 (L, ) is suppressed as much as possible, and its focal length (first convex lens 66
Distance between the center 77 and the first crossover 74:'
If efforts are made to reduce LI+□), a smaller beam spot can be formed at the first crossover point 74. The first crossover point 74 and the second convex lens 67 (
LX) and the center position 78 of β21.LX). While increasing L□ as much as possible, the distance E between the center position 78 of the second convex lens 67 and the target 18 L2. By reducing T, the image of the first crossover 74 can be formed on the target 18 in a more reduced size.

V2. For example, the applied voltage of V4 is 900 V, respectively.
If you set it to 300V and change only ■, G2
Position βG2+LI+β of the disk closer to the terminal electrode 65-cylindrical lens 66 and the disk-cylindrical lens on the mesh electrode side
La, a and focal length' Ll+ FI+ I! F2r
LZ changes as shown in FIG.

As shown in FIG. 5, the voltage ν3 of the defleftron electrode 4
When V is changed, the positions of both lenses hardly change, but the focal length, that is, the strength of the lenses, changes approximately in proportion to the magnitude of V3.

The smaller the lens, the stronger the lens. Therefore, the imaging of the first crossover 74 shown in FIG. 4 can be easily realized by adjusting v3. Furthermore, V2+ v:l
Depending on the selection, it is easy to further enhance the main idea shown in the fourth figure.

According to experiments, the operating conditions shown in Fig. 2(b)
As shown in the figure, it has been found that the conditions for imaging the crossover 74 once formed are more suitable for improving the performance of the electron tube.

Incidentally, a deflection voltage is superimposed on the defleftron electrode 4 for deflecting the electron beam. In this case, there is a sixth
A non-axis symmetric potential distribution as shown in the figure occurs, and the two disk-cylindrical lenses 66, 67 become distorted as shown in FIG.

FIG. 6 shows an example of the above phenomenon when v2 is 900 V,
When a deflection voltage of 60 V pp is applied to the defleftron electrode 4 under the conditions that V,1 is -30 V and V, is 300 V, that is, +30 V pp is applied to the deflection electrode at the top of Fig. 6.
V, the potential distribution when a deflection voltage of -50V is applied to the lower deflection electrode. For the reason shown in Figure 5, near the deflection electrode to which a positive deflection voltage is applied,
The convex lens is weak. The deflected electron beam always passes near the deflection electrode to which a positive deflection voltage is applied.

By the way, in the vicinity of the first convex lens 66, the beam has only a small amount of deflection and travels near the axis, so the non-axial symmetry of the convex lens has little effect on the focusing and deflection characteristics of the electron beam. However, since sufficiently deflected electrons pass through the second convex lens 67, the above-mentioned non-axial symmetry greatly affects the focusing and deflecting characteristics of the electron beam.

According to experiments, the second
The convex lens 67 acts to effectively compensate for the beam defocus caused by the deflection, as shown in FIG. It turns out that it is possible to form an image without focusing.

The optical characteristics of the outer edge of the second convex lens 67 depend not only on the electrode applied voltages v2 to v4 but also on the shape of the cylindrical electrode 19 electrically connected to the mesh electrode 17. Distance between the mesh electrode 17 and the end of the ring electrode 19 facing the defleftron electrode side! By setting □ (see FIG. 6) to 0.1 d to 5 dl with respect to the tube diameter d, it was possible to reduce not only the deflection defocus but also the figure distortion and beam miscollimation at the same time. This is because the fringing field near the cylindrical electrode 19 successfully complements the beam collimation effect.

As is clear from the above description, the present invention focuses and deflects the electron beam using two disc-cylindrical lenses that utilize defreftron electrodes, and at the same time, the electron beam The feature is that the above-mentioned disk-cylindrical lens has both functions without the need to newly provide a collimation lens for making the beam perpendicularly incident on the target.

FIG. 7 shows an embodiment in which the electrode configuration shown in FIG. 1 is applied to an image pickup tube having a triode type electron gun. 61 is a cathode that emits thermoelectrons, 62 is a G1 electrode, 63 is a G2 electrode,
64 is a beam restriction hole for extracting an appropriate amount of high quality (small divergence angle) beam from the extracted electron beam;
5 is a G2 terminal electrode added to the G2 electrode 63; 4 is a defleftron electrode for focusing and deflecting the beam; 17
18 is a mesh electrode, 18 is a target, 80 is a pin-shaped electrode for taking out a signal current, 81 is an indium ring for sealing the face plate 82 to the upper part of the glass envelope IO, 8
3 is a pedestal for attaching the mesh, 19 is a ring electrode, 8
Reference numeral 4 is a pull-out bottle for applying a required voltage to the electrode group.

The defleftron electrode 4 can be formed by processing a metal such as Cr'PA1 on which glass is vacuum-deposited on the inner surface of the envelope 10 into a desired pattern using etching or laser processing technology.

According to this electrode configuration, the electron beam 2 emitted from the electron gun section 1 is transferred to the G2 terminal electrode 65. Defleftron electrode 4. and mesh electrode group (mesh electrode 17. mesh support frame 8
1. It is focused onto the surface of the target 18 by a disk-cylindrical convex lens formed by a ring electrode 19).

If a deflection voltage is applied to the defleftron electrode 4 superimposed on the DC voltage V, the electron beam 2 can be deflected while maintaining the condition that it is perpendicularly incident on the surface of the target 18, as explained with reference to FIG. be able to. In this embodiment, the inner diameter of the glass envelope 10 (the defleftron electrode 4
) d, and the length l of the defleftron electrode,
When the ratio of 1 +/(L was changed and the change in characteristics was investigated, the results shown in Figure 8 were obtained.

Curve A in FIG. 8 is the amplitude modulation degree ARce at the center of the screen.

Curve B is the amplitude modulation degree ARco at the periphery of the screen, and the curve '
1IAC is the result of actually measuring the change in graphic distortion Δd.

From these experimental results, if 1+/d+ is selected to be around 1.5 times, ARce and ARco will be maximized and Δd will be minimized, and shading due to beam mislanding (not shown) will also be minimized. 1iiiI
It has been certified. The operating conditions in this experiment are 1h=9
00 V, V4=300 V, Vaha1 +/c
It was selected in the range of -100V to +50V depending on the L.

The value Vl (Δdmi
Figure 9 shows the results obtained for (1+/(L)) and the value of v3 at which AR is maximum vs (AR-, l). They do not match when it is more than 2, but they match when it becomes 2 or less.V, (8R,,,) and V
3 (Δdmin) means that both high resolution and low graphic distortion can be achieved.

However, when β, /d is less than 1, the aberration of the focusing lens system becomes significant, so that only relatively insufficient tube characteristics can be obtained as shown in FIG.

From the above study results, the practical value T of 1 +/d+. , L may be suitably 1 to 3 as shown in FIG.

The reason for this can be explained as follows.

A by lengthening the defleftron electrode 4! When +/d+ is increased, the antinode of the beam (G
2. Defined as the maximum diameter of the electron trajectory emitted from the tube axis near the tube axis at an angle of 5° with the axis), the aberration increases and the image point becomes blurred (the paraxial electron and the above-mentioned electron (defined as the distance between image points) increases as shown in curve B in the same figure.On the other hand, if the defleftron electrode is shortened and I! The deflection aberration increases due to the increase in the deflection angle, and the conditions for electrons to pass through the defleftron, that is, the axial potential φ
. Under conditions where (Z) is not negative, there is a limit to how strong the disk-cylindrical lens can be, making it difficult to ensure optimal focusing conditions for the electron beam.

By the way, in the image pickup tube to which the present invention is applied as shown in FIG. 7, if the defleftron electrode 4 is made of a ferromagnetic material such as permalloy instead of Cr or Al, the magnetic interference, which is essential when operating the image pickup tube, is eliminated. The thickness of the body can be reduced, making the entire device lighter. For example, if a thin film of a ferromagnetic material such as permalloy deposited to a thickness of several μm by sputtering or vacuum deposition is used as an electrode film, the required thickness of the magnetic barrier can be reduced by about half. can.

In order to obtain a practically sufficient magnetic shielding effect, the thickness of the permalloy must be approximately 0.8 W when the above-mentioned magnetic film is not used. However, by using the above-mentioned magnetic thin film defleftron electrode, the thickness of the magnetic barrier can be reduced to about half the conventional Q and 4 ms. Although the tube itself can generally be manufactured with a weight of several logs, the magnetic barrier weighs several tens of grams, which almost determines the total weight of the tube. Therefore, reducing the thickness of the magnetic shield is essential for reducing the weight of the device.

The effects of the present invention described above can be further enhanced by the following means.

FIG. 11 shows the diameter d of the G2 terminal electrode 65. Changes in the first disc-cylindrical lens 66 when changing the
The change in electron orbit due to . When d and □ are made smaller than a fraction of the diameter d of the defleftron electrode 4, FIG. 11(a) shows dG□.
There are two typical cases where d is approximately equal to d.

From FIG. 11, when the G2 end electrode 65 is made smaller, the center 77 of the first convex lens 66 moves closer to the G2 end electrode, and at the same time, the focal length 'LI+FI is also reduced, forming a stronger convex lens. Therefore, in the mode of operation in which the first crossover 74 is imaged onto the target 18 by the second disc-cylindrical lens 67, a smaller beam spot is obtained. Furthermore, instead of changing dGt, the same effect can be obtained by changing the shape of the G2 termination electrode 65, as shown in the second embodiment of FIG.

FIG. 13 shows an embodiment of the present invention.

In FIG. 13(a), another cylindrical electrode 91 is added between the defleftron electrode 4 and the mesh electrode 17, and a new cylinder-cylinder is formed between the two disc-cylindrical lenses 66 and 67. A lens 92 is provided, and instead of this convex lens primarily performing a focusing function, the second convex lens 67 is primarily configured to perform only a collimating function of the electron beam.

FIG. 13(b) shows a new cylindrical electrode 91 connected to the G2 terminal electrode 6.
The newly provided convex lens 92 has an effective synergistic effect with the first convex lens 66, and forms three convex lenses as shown in FIG. This allows a single, stronger convex lens to be formed.

(Effects of the Invention) When this invention is applied to a scanning electron beam system of an all-electrostatic type (SS type) image pickup tube, the number of lenses used for focusing and deflecting the electrons can be reduced to two, and the eight lenses occupy less space. Since a disk-cylindrical lens whose length is approximately half that of a conventional cylinder-cylindrical lens is used, the tube length can be shortened to about half or less compared to the conventional SS type. In addition, since the deflection electrode itself has a shielding effect from external magnetism,
The magnetic barrier added to the outside of the tube can be made thinner, and the overall weight of the device can be significantly reduced, making it possible to provide a device that is much smaller and lighter than conventional types.

In the present invention, since no concave lens effect exists within the tube, there is little divergence of electron trajectories and little deflection aberration. Therefore, it is possible to provide a device that meets the requirements of a high-definition television system that requires high resolution and high performance. For example, in the embodiment shown in FIG. 7, the diameter d1 of the defleftron electrode 4 is 16 mm, and the length β is 27 mm.
fl, the electron gun part 1 incorporates the triode type published in the Television Society of Electronics Equipment Research Group Sample ED343 (September 1978), and the Saticon film is used as the target, the voltage of the G2 terminal electrode 65 v
2 to 900■, and the voltage v4 of the mesh electrode 17 to 300V.
As a result of conducting a measurement experiment under the condition that the electron beam is focused on the target 18, that is, approximately Ov, the following performance was obtained.

Figure 14 shows the amplitude modulation degree AR of the prototype tube. IAJ (
Japan Electronics Industries Association)・Established B! This is the result of actual measurement using a +B+ test chart. AR is Bg in the center of the screen, 40
Approximately 70% of the value was obtained for 0 TV books, and more than 50% of the central value was obtained for the periphery of the screen. Further, figure distortion was less than 0.5%, and shading was at an almost negligible level. Table 1 shows a comparison of the dimensions, weight, and performance of the image pickup tube of this example with a typical image pickup tube of the same diameter that uses a ground-type focusing deflection system and incorporates the same electron gun as this example. .

As is clear from Table 1, according to the present invention, it is possible to obtain an image pickup tube that is extremely compact and has high performance.

Table 1 Weight and dimensions of the image pickup tube according to the present invention and the conventional type,
Comparison of characteristics Also, in the embodiment shown in FIG. 11(a), the diameter dCZ of the G2 terminal electrode 65 is
If the value is reduced to less than 2 of 1, the resolution will further increase.

The present invention described above can be directly applied to a CRT by using a fluorescent screen instead of the image pickup tube target 18. CI? In the case of T, there is no need to make the electron beam 2 enter the target 18 perpendicularly, so there is no problem even if the mesh electrode 17 is omitted.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a first embodiment of an all-electrostatic image pickup tube according to the present invention, and FIG. 2 is a diagram showing the potential distribution inside the tube (( Figure 3 is a diagram showing the axial potential distribution inside the image pickup tube in the embodiment of Figure 1. Figure 4 is a diagram showing the typical electron trajectory (Figure (b)). FIG. 5 is a diagram showing an example of the operation of the electron beam when no deflection voltage is applied in the first embodiment.
lG vs. defleftron electrode voltage for the example of
Z+LI+ 'LI+? + 'LI+Fl+ 'F2+
L! FIG. 6 is a diagram showing an example of electron beam operation when a deflection voltage is applied. FIG. 7 is a diagram showing an example of electron beam operation when a deflection voltage is applied. FIG. FIG. 8 is a diagram showing the tube length dependence of the tube characteristics of the image pickup tube shown in FIG. 7, and FIG. Figure 10 is a diagram showing the tube length dependence of electron beam imaging characteristics in the image pickup tube shown in Figure 7. Figure 11 shows how the lens changes when the diameter d6□ of the G2 terminal electrode is changed. Fig. 12 is a diagram showing the second embodiment of the present invention (Figs. (a) to (e)) in which the shape of the G2 terminal electrode is variously changed; 1
Figure 3 shows a third embodiment of the present invention ((a) figure, (b) figure)
FIG. 14 is a diagram showing resolution characteristics obtained for the first embodiment of the present invention. FIG. 15 is a diagram showing a focusing deflection section of a conventional all-electrostatic image pickup tube. The figure is a diagram showing equipotential lines and electron beam trajectories in the fifteenth illustrated image pickup tube. 1-Electron gun section 2...Electron beam 3-Cylindrical electrode 4-Defreftron electrode 5-Cylindrical electrode
10-Glass envelope 17--Methoche electrode
18・-Target Node 19・～ Ring electrode
61- Cathode 62°-・-G1 electrode
63-...G2 electrode 64=--Beam restriction hole 65
-・G2 terminal electrode 66 - first convex lens 67 - second
Convex lens 71 - - β1 orbit of electron 72 - α orbit of electron 73 - β2 orbit of electron 74 - First crossover 75 - Second crossover 76 - Image plane position 77 - Center 7 of lens 66
8-- Center of lens 67 80-- Signal extraction bin 81- Indium ring 82-- Face plate 83-
The mesh is attached to the pedestal 84 - lead pin 91 - additional cylindrical electrode 92
-Additional convex lens f/l shield jj't/ds σ to the belly - Image! TV book

Claims (1)

[Claims] 1. A plurality of divided cylindrical deflection electrodes disposed inside the outer tube of the electron tube, and at least a disk-shaped deflection electrode disposed on the electron gun side of the cylindrical deflection electrode, or from the tube axis direction. An electric field is focused so as to make the axial second-order differential of the potential distribution on the tube axis positive. An electron tube characterized by comprising an electric field deflection section. 2. The electron tube according to claim 1, wherein the ratio l_1/d_1 of the length l_1 and diameter d_1 of the cylindrical deflection electrode is set in the range of 1.0 to 3.0. 3. The diameter of the disk-shaped or circular electrode viewed from the tube axis direction is set to 1/2 or less of the diameter of the cylindrical deflection electrode. Or the electron tube described in item 2. 4. A length electrode is disposed between the cylindrical deflection electrode and the disk-shaped electrode disposed at the other end, and from the disk-top electrode to the end of the ring electrode on the cylindrical deflection electrode side. The electron tube according to any one of claims 1 to 3, wherein the distance l_M_R is set in the range of 0.1d_1 to 0.5d_1. 5. The electron tube according to any one of claims 1 to 4, wherein the cylindrical deflection electrode is formed of a magnetically positive thin film. 6. The electron tube according to any one of claims 1 to 5, wherein the disk-shaped electrode disposed at the other end of the cylindrical deflection electrode is formed of a fluorescent screen. 7. Claim 1, characterized in that a cylindrical electrode is further disposed between the cylindrical deflection electrode and the disc-shaped or circular electrode when viewed from the tube axis direction. 7. The electron tube according to any one of items 6 to 6. 8. A cylindrical electrode is further disposed between the cylindrical deflection electrode and the disc-shaped electrode disposed at the other end of the cylindrical deflection electrode. The electron tube according to any one of item 6.