JP2000323061A - Cathode-ray tube electron gun - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cathode-ray tube electron gun which can obtain a good resolution by effectively decreasing spherical aberration of an electrostatic lens of a main lens part. SOLUTION: In an electron gun having a main lens part for accelerating and focusing an electron beam, the main lens part is composed of a plurality of grids including a first grid 35 to which at least a medium voltage is supplied and a third grid 37 to which a plate voltage is supplied. At least one of second grid 36 is provided in an electron beam proceeding direction between the first grid 35 and the third grid 37, to which voltage higher than the medium voltage supplied to the first grid 35 and lower than the plate voltage is supplied. In the second grid 36, an opposed surface of the first grid 35 side and an opposed surface of the third grid 37 side are formed on a tubular opening hole part in common with a plurality of electron beams. A short diameter of the tubular opening hole part of the second grid 36 and a length of the second grid 36 along an electron beam proceeding direction are fixed in a prescribed relation so as not to separate a lens electric field formed between the first grid 35 and the third grid 37 by means of the second grid 36.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electron gun for a cathode ray tube, and more particularly to an electron gun for a cathode ray tube used for a color cathode ray tube or the like.

[0002]

2. Description of the Related Art In general, a typical color picture tube as a cathode ray tube has an envelope composed of a panel 1 and a funnel 2 integrally joined to the panel 1, as shown in FIG. On the inner surface of the panel 1, there is formed a phosphor screen 3 composed of a striped or dot-shaped three-color phosphor layer that emits red, green, and blue light. Further, a shadow mask 4 having a large number of beam passage holes formed therein is mounted on the inner surface of the panel 1 so as to face the phosphor screen 3. On the other hand, in the neck 5 of the funnel 2,
An electron gun 7 for emitting three electron beams 6B, 6G, 6R is provided. Then, 3 emitted from the electron gun 7
The electron beams 6B, 6G, 6R are deflected by the horizontal and vertical deflection magnetic fields generated by the deflection yoke 8 mounted outside the funnel 2, and are directed onto the phosphor screen 3 via the shadow mask 4, and this phosphor screen 3 is 3
A color image is displayed on the phosphor screen 3 by being scanned horizontally and vertically by the electron beams 6B, 6G, 6R.

In a color cathode ray tube having such a structure,
The resolution of the image depends on the size and shape of the spot on the phosphor screen 3 of the electron beam generated from the electron gun and focused on the phosphor screen 3. As one of means for increasing the resolution of this image, a method of reducing the spherical aberration of the electric field lens by increasing the aperture of the main lens portion of the electron gun as much as possible is generally adopted.

Generally, the main lens portion of an electron gun of a color cathode ray tube has electron beam passing holes corresponding to the three electron beams 6B, 6G, and 6R as shown in FIGS. 2A and 2B. And the final accelerating electrode, and the electron beam passage holes are configured to face each other. Since the aperture of the electric field lens formed by the focusing electrode and the final accelerating electrode is limited by the diameter of the electron beam passage hole, it cannot be made larger than the mechanical limitation of the electron beam passage hole.

To solve the above problem, Japanese Patent Publication No. 2-1
In the color cathode ray tube disclosed in 8540 and the like, as shown in FIGS. 3 (a) and 3 (b), the cylindrical electrodes 1la, 13a, which are common apertures for three electron beams, and the passage of each of the three electron beams. The holes 12a, 12b, 12c, 14a,
A main lens portion is formed by the focusing electrode 9 and the final accelerating electrode 10 which are composed of the plate electrodes 12 and 14 having 14b and 14c. By forming the main lens portion in this way, the electric field lenses generated in the trajectory of the three electron beams passing through the main lens portion partially overlap each other, so that a large-diameter main lens portion electric field is formed. Can be.
Therefore, it is possible to reduce the adverse effect on the spot due to the spherical difference. In addition, since the lens magnification of the main lens unit can be reduced, a spot having a smaller diameter than before can be generated on the screen. However, since the electron gun is located in the neck of the cathode ray tube and the opening diameter of the cylindrical electrode is limited by the inner diameter of the neck, there is a limit in improving the spot by increasing the opening diameter of the cylindrical electrode.

Further, if the diameter of the neck is increased to increase the diameter of the opening of the cylindrical electrode, the deflection sensitivity decreases when the electron beam is horizontally and vertically scanned by the deflection yoke. There are adverse effects such as an increase.

Further, means for solving such a problem is disclosed in Japanese Patent Application Laid-Open No. Hei 8-22780. As shown in FIG. 4, the color cathode ray tube disclosed in this publication has a cylindrical electrode 1 serving as a common aperture for passing three electron beams.
9a, 21a and the aperture 18a through which each of the three electron beams passes.
A focusing electrode 15 and a final accelerating electrode 16 composed of plate electrodes 18 and 20 having 18b, 18c, 20a, 20b and 20c, and between the focusing electrode 15 and the final accelerating electrode 16, the focusing electrode 15 and An auxiliary electrode 17 serving as a common through hole for the three electron beams coaxial with the final acceleration electrode 16 is arranged to form a main lens portion. With such a structure, the potential distribution of the electric field lens can be made gentler in the beam traveling direction without increasing the neck diameter. Therefore, in the main lens portion having such a structure, it is said that the spherical aberration of the electric field can be made smaller than that disclosed in Japanese Patent Publication No. 2-18540 described above. However, in the structure of the main lens portion, if the length of the auxiliary electrode along the traveling direction of the electron beam is increased, the electric field lens formed by the main lens portion is separated before and after the auxiliary electrode, and substantially. Two electric field lenses are formed. As an example of the main lens portion of the electron gun having such a structure, in a structure having a focusing electrode and a final accelerating electrode and an auxiliary electrode inserted between the focusing electrode and the final accelerating electrode coaxially, The opening on the mating surface has an opening common to the three electron beams, the vertical diameter of which is the minor diameter of the common opening is 7 mm, and the length of the auxiliary electrode along the electron beam traveling direction is 6 mm. In the case of, the result of calculating the on-axis potential distribution with and without the auxiliary electrode is shown in graph 1 of FIG. 5, and the result of calculating the second derivative thereof is shown in graph 2 of FIG. Indeed, from Graph 1,
The change in the axial potential distribution is more gradual when there is no auxiliary electrode than when there is no auxiliary electrode. However, in the second derivative of the on-axis potential distribution, two positive regions and two negative regions appear alternately when the auxiliary electrode is provided. That is, the electric field lens of the main lens portion formed between the focusing electrode and the final acceleration electrode is divided by the auxiliary electrode. In effect, the electron beam is given a lens effect as two small lenses. Therefore, the effect of increasing the diameter of the main lens portion is impaired, and a good electron beam spot cannot be obtained.

[0008]

In order to increase the resolution of an image on the phosphor screen 3, there is a method of reducing the spherical aberration of the electric field lens by increasing the diameter of the main lens portion of the electron gun as much as possible. However,
Since the aperture of the electric field lens formed by the focusing electrode and the final accelerating electrode is limited by the aperture of the electron beam passage hole, there is a problem that it cannot be made larger than the mechanical limitation of the electron beam passage hole.

In order to solve this problem, a focusing electrode 9 and a plate electrode each having a cylindrical electrode serving as a common aperture for passing three electron beams and a plate electrode having a hole for passing each of the three electron beams are provided. A main lens portion is formed by the final acceleration electrode 10,
There is a technique for forming a large-diameter main lens portion electric field. However, in this structure, the electron gun is located inside the neck of the cathode ray tube, and the opening diameter of the cylindrical electrode is limited by the inner diameter of the neck. It is said that there is a limit.

If the diameter of the neck is enlarged to increase the diameter of the opening of the cylindrical electrode, the deflection sensitivity becomes low when the electron beam is horizontally and vertically scanned by the deflection yoke. There is a problem such as increase.

In order to solve such a problem, between the focusing electrode 15 and the final accelerating electrode 16, an auxiliary electrode 17 serving as a common through-hole for three coaxial electron beams is provided, and a main lens portion is provided. Is formed. However, in such a structure of the main lens portion, if the length of the auxiliary electrode along the traveling direction of the electron beam is increased, the electric field lens formed by the main lens portion is separated before and after the auxiliary electrode, and is substantially As a result, two electric field lenses are formed. That is, the electric field lens of the main lens portion formed between the focusing electrode and the final acceleration electrode is divided by the auxiliary electrode. In effect, the electron beam is given a lens effect as two small lenses. Therefore, the effect of increasing the diameter of the main lens portion is impaired, and there is a problem that a good electron beam spot cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to increase the diameter of a neck and to separate a lens electric field formed by a main lens portion. Another object of the present invention is to provide a cathode ray tube electron gun which generates a spot for obtaining a good resolution by providing a main lens unit structure for effectively reducing the spherical aberration of an electric field lens of the main lens unit.

[0013]

An electron beam forming section for forming and emitting a plurality of electron beams, and a main lens section for accelerating and converging the electron beam, wherein the main lens section has at least a medium voltage. An electron gun for a cathode ray tube comprising a plurality of grids including a first grid to be supplied and a third grid to which an anode voltage is supplied, wherein the first grid is provided between the first grid and the third grid. At least one second grid supplied with a voltage higher than the medium voltage supplied to the grid and lower than the anode voltage supplied to the third grid is arranged along the traveling direction of the electron beam. The second grid has an opposing surface on the first grid side and an opposing surface on the third grid side formed in a tubular opening common to a plurality of electron beams. Grid of Lens electric field formed between the second
The short diameter of the cylindrical opening of the second grid on the first grid side is set to R so that it is not separated by the grid of R.
1. When the short diameter of the cylindrical opening on the third grid side is R2, 0.3 ≦ L / ｛(R1 + R2) between the second grid and the length L along the electron beam traveling direction. ) / 2｝ ≦ 0.6.

In the present invention, with the above configuration, the potential distribution of the electric field along the beam traveling direction of the main lens portion formed between the first grid and the third grid has a gentle gradient, In addition, the electric field lens formed between the first grid and the third grid is the second electric field lens.
And acts on the electron beam as one large-aperture lens as a whole without being separated by the grid. Therefore, the spherical aberration of the electric field of the main lens portion can be effectively reduced, and a good spot can be obtained.

[0015]

7 (a) and 7 (b) are schematic sectional views showing an electron gun portion of a cathode ray tube according to one embodiment of the present invention. In FIG. 7 (a), three cathodes KB and K for generating an electron beam, which are provided with heaters (not shown), are provided.
G, KR, first grid 31, second grid 32, third
Grid 33, fourth grid 34, fifth grid 35,
The sixth grid 36, the seventh grid 37, and the convergence cup CP are arranged in this order, and these electrodes are supported and fixed by an insulating support (not shown). The first grid 31 is a thin plate-like electrode, and has three electron beam passage holes having a small hole diameter. Second grid 3
Reference numeral 2 also denotes a thin plate-like electrode, in which three electron beam passage holes having a small hole diameter are formed. The third grid 33 is formed by combining one cup-shaped electrode and a thick plate electrode. On the second grid 32 side, three electron beam passing holes having a slightly larger hole diameter than the electron beam passing hole of the second grid 32 are provided. Are formed, and three electron beam passage holes having a large hole diameter are formed on the fourth grid 34 side. The fourth grid 34
The open ends of two cup-shaped electrodes are brought into contact with each other, and three electron beam passage holes each having a large diameter are formed. The fifth grid 35 has a length 2 in the electron beam passing direction.
The cylindrical electrode 51 as shown in FIG. 8A having a common opening for the cup-shaped electrode, the plate-shaped electrode 52, and the three electron beams.
When the fifth grid is viewed from the sixth grid side, it is formed in a shape as shown in FIG. 8B. Next, the sixth
The grid has an aperture common to the three electron beams.
It is composed of two cylindrical electrodes 61 and 62 as shown in FIG. The seventh grid has a cylindrical electrode 7 having an opening common to the three electron beams as shown in FIG.
The plate-like electrodes 72 having one or three electron beam passage holes are arranged in this order, and the seventh grid has a shape as shown in FIG. 2B when viewed from the sixth grid side. .

A voltage Ek of about 100 to 150 V is applied to the three cathodes KB, KG, and KR, the first grid 31 is grounded, and the second grid 32 and the fourth grid 3
4 is applied with a voltage V2 of about 600 to 800 V, and a third grid 33 and a fifth grid 35 are applied with a focusing voltage V3 of about 6 to 10 kV, which is a medium voltage, and a seventh grid is applied. An anode voltage Va of about 25 to 34 kv is applied to 37, and a voltage V6 substantially intermediate between the fifth grid 35 and the seventh grid 37 is applied to the sixth grid 36 by the resistor 100 provided near the electron gun. Supplied.

Here, the short diameter of the opening on the fifth grid side and the short diameter of the opening on the seventh grid side of the sixth grid 36 are 7 mm, which are the same diameter. FIG. 9 is a graph 3 showing a calculation result of a change in on-axis potential when the electrode length along the electron beam advancing direction is increased to 2 mm, 4 mm, and 6 mm. As shown in the graph 3, as the electrode length L of the sixth grid 36 is increased, the change in the on-axis potential becomes gentle. Further, when the electrode length L of the sixth grid 36 along the electron beam traveling direction is extended to 2 mm, 4 mm, and 6 mm, the electrode length L of the sixth grid 36 along the electron beam traveling direction and the electrode opening length are increased. The ratio L / R to the hole minor diameter R;
The results of calculating the relationship with the effective aperture (vertical direction and horizontal direction) are shown in graph 4 of FIG. 10 and graph 5 of FIG. As can be seen from these graphs, the effective aperture becomes the largest when the ratio L / R is set to an appropriate value. When the ratio L / R is further increased,
That is, if the electrode length L of the sixth grid 36 along the electron beam traveling direction is too long, the effective aperture is reduced.

Therefore, the effective range in which the sixth grid 36 is substantially provided to improve the electron beam spot is an effective aperture capable of maximizing the diameter of the main lens portion capable of obtaining a good electron beam spot. Maximum value, especially the sixth
An intermediate value from the maximum value of the effective aperture in the opening portion minor axis direction of the grid 36, that is, the vertical direction, until the minor diameter, which is the minimum diameter of the mechanical aperture of the sixth grid 36, is equal to the effective aperture. It is up to where to take. In order to obtain such an effective execution diameter, the ratio L / R of the electrode length L and the electrode opening portion short diameter R along the electron beam traveling direction of the sixth grid 36 is as follows.
According to graph 4, it is between 0.3 and 0.8. That is, the ratio L
By setting / R between 0.3 and 0.6, the effective aperture can be effectively enlarged.

In the embodiment according to the present invention, a good electron beam spot can be obtained by adopting such a structure. In particular, in the above-described embodiment of the present invention, the ratio L
The effective aperture takes the maximum value near /R=0.45. Calculation of the second derivative of the on-axis potential distribution in the case where there is the sixth grid 36 of the embodiment of the present invention at this time and in the case of the conventional example where there is no sixth grid 36 of the embodiment of the present invention for comparison The result is graph 6 in FIG.
Is shown in As in the embodiment of the present invention, the sixth
When there is a grid, the sixth embodiment is used in the embodiment of the present invention.
The lens electric field can be formed in a longer section than when there is no grid, and separation of the lens electric field formed in the main lens portion, which causes a decrease in the effective aperture, can be prevented. That is, the ratio L / R of the electrode length L and the electrode opening minor axis R along the electron beam traveling direction of the sixth grid 36 provided between the fifth grid 35 and the seventh grid 37 is 0.3 ≦ L. By setting /R≦0.6 (1), the effective aperture can be efficiently expanded, and a good electron beam spot can be obtained.

When the short diameter of the electrode opening on the fifth grid side of the sixth grid 36 is R1 and the short diameter of the electrode opening on the seventh grid side is R2, in the above embodiment, R1 = R2
= R, but the penetration of the electric field into the sixth grid 36 is limited by the short diameter as described above. Therefore, R
When 1 ≠ R2, the side having a large minor axis has a large penetration of the electric field, and the side having a small minor axis has a small penetration of the electric field. Therefore, the penetration of the electric field into the sixth grid is
Constrained by the average of the short diameters R1 and R2, the constraint (1) of the sixth grid in the above embodiment is rewritten as 0.3 ≦ L / {(R1 + R2) / 2} ≦ 0.6. By configuring the sixth grid 36, it is possible to efficiently expand the aperture and obtain a good electron beam spot.

In the above, one embodiment of the present invention has been described. In the above-described embodiment, the fifth grid 35 to which a focusing voltage of about 6 to 10 kv is applied and the anode grid to which an anode voltage of about 25 to 34 kv is applied. Although only the sixth grid 36 is arranged between the seventh grid 37, the fifth grid 35 and the seventh grid 37 are arranged.
A plurality of grids (the sixth grid) are inserted between the grids 37.
A grid 36 is included. ), A voltage is supplied to the inserted grid so that the voltage gradually increases from the fifth grid side toward the seventh grid side, and the cylinder of each inserted grid is supplied. When the short diameter of the cylindrical opening on the fifth grid side is R1 and the short diameter of the cylindrical opening on the seventh grid side is R2, the electron beam travels in the second grid. If the arrangement is such that the length L along the line is in the relationship of 0.3 ≦ L / {(R1 + R2) / 2} ≦ 0.6, the same grid as in the above-described embodiment is used between adjacent grids. Since the effect can be obtained, the same effect as that of the above-described embodiment can be ensured for the entire main lens portion. Further, the fifth grid 35
A grid inserted between the third and seventh grids 37 is provided with electron beam passage holes corresponding to each of the three electron beams,
In the electron beam passage hole, when the short diameter of the passage hole on the fifth grid side is R1 and the short diameter of the passage hole on the seventh grid side is R2, along the electron beam traveling direction of the inserted grid. If the length L is configured and arranged so as to satisfy the relationship of 0.3 ≦ L / {(R1 + R2) / 2} ≦ 0.6, at each opening, the same as in the above-described embodiment is applied. Since the effect can be obtained, it goes without saying that the same effect as that of the above-described embodiment can be secured for the entire main lens portion.

In the inserted grid, the fifth grid-side facing surface and the seventh grid-side facing surface are cylindrical openings common to the three electron beams, and are the cylindrical electrodes. Inside the grit to be inserted,
There is a plate-like electrode having an electron beam passage hole corresponding to each of the three electron beams, and the surface of the plate is arranged substantially perpendicular to the electron beam traveling direction. In the above, when the minor axis on the fifth grid side is R1 and the minor axis on the seventh grid side is R2, along the electron beam traveling direction from the fifth grid side opening of the inserted grid to the plate electrode. 0.15 ≦ L1 / {(R1 + R2) / 2} that is the length L1 of the inserted grid and the length L2 along the electron beam traveling direction from the opening on the seventh grid side to the plate electrode of the inserted grid. ≦ 0.3 0.15 ≦ L2 / {(R1 + R2) / 2} ≦ 0.3, and the electron beam passage hole of the plate-shaped electrode arranged inside the inserted electrode The minimum diameter of the cylindrical opening diameter in the same direction as the minor diameter direction When r is set, the plate thickness T of the plate electrode is configured to satisfy the relationship of T / r ≦ 0.6, and if arranged, the inside of the cylindrical opening of the sixth grid 36 and the plate electrode Since the same effect as in the above-described embodiment can be obtained in each portion of the beam passage hole, the same effect as in the above-described embodiment can be ensured as a whole of the main lens unit. In the above-described embodiment, the electron gun having the QPF structure has been described. However, it is needless to say that the same effect can be obtained without being limited to the QPF structure as long as the electron gun has a similar main lens portion structure. Nor.

[0023]

According to the present invention, there is provided an electron beam forming unit for forming and emitting a plurality of electron beams, and a main lens unit for accelerating and converging the electron beams, wherein the main lens unit is supplied with at least a medium voltage. An electron gun for a cathode ray tube comprising a plurality of grids including a first grid and a third grid to which an anode voltage is supplied, wherein the first grid is supplied to the first grid between the first grid and the third grid. At least one second voltage, which is supplied with a voltage higher than a medium voltage applied and lower than an anode voltage supplied to the third grid.
Are arranged in the traveling direction of the electron beam,
In the second grid, the opposing surface on the first grid side and the opposing surface on the third grid side form a cylindrical opening common to a plurality of electron beams, and are provided between the first grid and the third grid. In order to prevent the lens electric field formed by the second grid from being separated by the second grid, the short diameter of the cylindrical opening of the second grid and the length of the second grid along the electron beam advancing direction are determined. To maintain a proper relationship between them. With the above configuration, the electric field lens formed in the main lens portion can be smoothly separated from the on-axis potential along the beam traveling direction without being separated before and after the second grid. In addition, the spherical aberration can be greatly reduced. That is, the electric field formed by the main lens portion can have a function of converging the electron beam as a single lens as a whole, and a good spot can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a structure of a general cathode ray tube.

FIGS. 2A and 2B are a cross-sectional view and a plan view schematically showing an electron gun for a cathode-ray tube mounted on a conventional cathode-ray tube.

3 (a) and 3 (b) are a cross-sectional view and a plan view schematically showing the structure of an electrode of a main lens portion of another example of a cathode ray tube electron gun mounted on a conventional cathode ray tube.

FIG. 4 is a view showing a structure of a main lens electrode of a third electron gun for a cathode ray tube mounted on a conventional cathode ray tube.

FIG. 5 is a graph showing on-axis potential distribution of a lens electric field in a conventional example with and without an auxiliary electrode in a main lens portion.

FIG. 6 is a graph showing the second derivative of the on-axis potential distribution of a lens electric field in a conventional example with and without an auxiliary electrode in a main lens portion.

FIG. 7 is a schematic sectional view showing one embodiment of an electron gun for a cathode ray tube according to the present invention.

FIGS. 8A and 8B are plan views showing electrode shapes used in a cathode ray tube electron gun according to the present invention.

FIG. 9 is a graph showing a change in on-axis potential distribution when the length of the sixth grid in the example of the present invention along the electron beam direction is changed.

FIG. 10 is a graph showing a relationship between a ratio L / R of an electrode length L and an electrode opening portion minor diameter R along an electron beam traveling direction of a sixth grid and an effective aperture (vertical direction).

FIG. 11 is a graph showing a relationship between a ratio L / R of an electrode length L and an electrode opening minor axis R along a traveling direction of an electron beam of a sixth grid and an effective aperture (horizontal direction).

FIG. 12 shows a calculation result of a second derivative of an axial potential distribution in a case where there is a sixth grid according to the embodiment of the present invention and a conventional case where there is no sixth grid according to the embodiment of the present invention as a comparison. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Panel 2 ... Funnel 3 ... Phosphor screen 4 ... Mask 5 ... Neck 6B, 6G, 6R ... Electron beam 7 ... Electron gun 8 ... Deflection yoke 1 la, 13a ... Cylindrical electrode 12, 14 ... Plate electrode 12a, 12b , 12c ... electron beam passage holes 14a, 14b, 14c ... electron beam passage holes 15 ... focusing electrode 18, 20 ... plate electrode 16 ... final acceleration electrode 17 ... auxiliary electrodes 18a-18C, 20a-20C ... electron beam passage Holes 19a, 21a: cylindrical electrodes KR, KG, KB: cathodes 31 to 37: grid 100: resistors

Claims (8)

[Claims] 1. An electron beam forming unit for forming and emitting a plurality of electron beams, and a main lens unit for accelerating and converging the electron beams, wherein the main lens unit is supplied with at least a medium voltage. An electron gun for a cathode ray tube comprising a plurality of grids including a first grid and a third grid to which an anode voltage is supplied, wherein the first grid is disposed between the first grid and the third grid.
At least one second grid supplied with a voltage higher than the medium voltage supplied to the grid and lower than the anode voltage supplied to the third grid is arranged along the traveling direction of the electron beam. And the second grid is the first grid
The opposite surface on the grid side and the opposite surface on the third grid side are formed in a cylindrical opening common to a plurality of electron beams,
When the short diameter of the cylindrical opening on the first grid side is R1 and the short diameter of the cylindrical opening on the third grid side is R2, An electron gun for a cathode ray tube, wherein a length L of a grid along a traveling direction of an electron beam is defined as 0.3 ≦ L / {(R1 + R2) / 2} ≦ 0.6. 2. A plurality of grids satisfying a condition of the second grid are arranged between a first grid and a third grid along a traveling direction of an electron beam.
The grid satisfying the configuration conditions of
2. An electron gun for a cathode ray tube according to claim 1, wherein a voltage is sequentially increased from said grid side toward said third grid side. 3. A third grid-side opening of the first grid and a first grid-side opening of the third grid are formed in a plurality of cylindrical openings common to electron beams. The electron gun for a cathode ray tube according to claim 1, wherein 4. A plurality of grids satisfying a configuration condition of the second grid are arranged between a first grid and a third grid along an electron beam traveling direction, and the plurality of second grids are arranged. 4. The electron gun for a cathode ray tube according to claim 3, wherein a voltage that sequentially increases in voltage from the first grid side to the third grid side is supplied to a grid satisfying the above configuration conditions. 5. An electron beam forming unit for forming and emitting a plurality of electron beams, and a main lens unit for accelerating and converging the electron beams, wherein the main lens unit is supplied with at least a medium voltage. A cathode ray tube electron gun comprising a plurality of grids including a first grid and a third grid to which an anode voltage is supplied, comprising: an opposed surface of the first grid on a third grid side; The opposing surface on the first grid side is formed in a cylindrical opening common to a plurality of electron beams, and
At least one between a third grid and a third grid is supplied with a voltage higher than the medium voltage supplied to the first grid and lower than the anode voltage supplied to the third grid. A second grid is disposed along the traveling direction of the electron beam, and the second grid is provided with electron beam passage holes corresponding to each of the plurality of electron beams. When the minor axis of the electron beam passage hole on the first grid side is R1 and the minor axis of the electron beam passage hole on the third grid side is R2,
An electron gun for a cathode ray tube, wherein a length L of the second grid along a traveling direction of the electron beam is defined as 0.3 ≦ L / {(R1 + R2) / 2} ≦ 0.6. 6. A plurality of grids satisfying a configuration condition of the second grid are arranged between a first grid and a third grid along an electron beam traveling direction. 6. The electron gun for a cathode ray tube according to claim 5, wherein a voltage that sequentially increases in voltage from the first grid side to the third grid side is supplied to a grid satisfying the above configuration conditions. . 7. An electron beam forming unit for forming and emitting a plurality of electron beams, and a main lens unit for accelerating and focusing the electron beams, wherein the main lens unit is supplied with at least a medium voltage. An electron gun for a cathode ray tube comprising a plurality of grids including a first grid and a third grid to which an anode voltage is supplied, comprising: a third grid-side facing surface of the first grid; The opposing surface on the first grid side is formed in a tubular opening common to a plurality of electron beams, and is supplied to the first grid between the first grid and the third grid. At least one second grid, which is supplied with a voltage higher than the voltage of the second grid and lower than the anode voltage supplied to the third grid, is arranged on the first grid side. Face and third An opposing surface on the grid side is formed in a cylindrical opening common to a plurality of electron beams, and inside the second grit serving as the cylindrical electrode, each of the plurality of electron beams corresponds to each of the plurality of electron beams. A plate-like electrode having an electron beam passage hole is provided, and the surface of the plate-like electrode is disposed substantially perpendicular to the electron beam traveling direction.
Assuming that the minor axis on the grid side of the second grid is R1 and the minor axis on the third grid side is R2, along the electron beam traveling direction from the tip of the opening of the second grid to the plate electrode. The length L1 of the hook and the length L2 along the electron beam traveling direction from the tip of the opening of the second grid on the third grid side to the plate electrode are 0.15 ≦ L1 / R1 ≦ 0.3. 0.15 ≦ L2 / R2 ≦ 0.3, and a plate in the minor diameter direction of the cylindrical opening of the electron beam passage hole of the plate-shaped electrode disposed inside the second electrode. The plate diameter of the plate-like electrode is represented by
An electron gun for a cathode ray tube, characterized in that T / r ≦ 0.6. 8. A plurality of grids satisfying a configuration condition of the second grid are arranged between the first grid and the third grid along the traveling direction of the electron beam. 8. The electron gun for a cathode ray tube according to claim 7, wherein a voltage that sequentially increases in voltage from the first grid side to the third grid side is supplied to a grid satisfying the configuration conditions.