JPH08162041A - Electron gun for cathode-ray tube - Google Patents

Abstract

PURPOSE: To improve the resolution of a cathode-ray tube by arranging quadrupole lenses on the upper stream and lower stream of a main lens, respectively, and making the electron beam passing hole of a control electrode into a vertically long form. CONSTITUTION: This electron gun for cathode-ray tube has cathodes K1 -K3 , an accelerating electrode G2 , and a main lens ML. Further, it also has a control electrode G1 having an electron beam passing hole having a vertically long form. A first quadrupole lens QP1 having diffusing action in the vertical direction to an electron beam and focusing action in the horizontal direction when the electron beam is collided with the peripheral part of a phosphor screen surface is provided between the accelerating electrode G2 and the main lens ML. A second quadrupole lens QP2 having focusing action in the vertical direction of the electron beam and diffusing action in the horizontal direction when the electron beam is collided with the center part of the phosphor screen surface is provided on the lower stream of the main lens ML, and dynamic convergence devices CP1 -CP4 are provided on the lower stream of the second quadrupole lens QP2 .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun for a cathode ray tube used for a color cathode ray tube which constitutes, for example, a color picture tube or a color display device.

[0002]

2. Description of the Related Art Generally, the resolution characteristics of color cathode ray tubes are
It largely depends on the size and shape of the electron beam spot on the phosphor screen surface. That is, unless the spot diameter of such an electron beam spot is close to a perfect circle, good resolution characteristics cannot be obtained.

As the deflection angle of the electron beam increases, the trajectory of the electron beam from the electron gun for the cathode ray tube to the phosphor screen surface becomes longer. Therefore, if the focus voltage is maintained so that an electron beam spot with a small diameter and a perfect circle can be obtained at the central portion of the phosphor screen surface, the peripheral portion of the phosphor screen surface will be in an overfocus state. As a result, an electron beam spot with a small diameter and a perfect circle cannot be obtained in the peripheral portion of the phosphor screen surface, and good resolution cannot be obtained.

Therefore, in recent years, as the deflection angle of the electron beam becomes larger, that is, with respect to the electron beam impinging on the peripheral portion of the phosphor screen surface, the focus voltage is increased to weaken the main lens action. An electron gun for a cathode ray tube has been devised. However,
This dynamic focus system is not very suitable for an in-line three-beam system electron gun for a cathode ray tube. That is,
In a conventional cathode-ray tube electron gun of the in-line three-beam system in which three cathodes are arranged in a straight line, if the deflection magnetic field of the deflection yoke is a uniform magnetic field, even if the central portion of the phosphor screen surface is converged As shown in FIG. 12, a vertical bow-shaped convergence error (overconvergence) occurs in the upper, lower, left, and right peripheral portions of the body screen surface. In FIG. 12, R
(Red) and B (blue) show double-sided electron beams, and G (green) shows a central electron beam.

Therefore, conventionally, the horizontal deflection magnetic field distribution by the deflection yoke has a pincushion shape, and the vertical deflection magnetic field distribution has a barrel shape for dynamic convergence. However, when the deflection yoke having such a configuration is used, the electron beam passing through the deflection yoke and deflected toward the peripheral portion of the phosphor screen surface has a focusing action (convex lens) in its vertical direction (longitudinal direction). Effect), while receiving a diverging action (concave lens effect) in the horizontal direction (lateral direction). As a result, the electron beam spot in the peripheral portion of the phosphor screen surface does not have a perfect circle but has a horizontally long shape. Therefore, there are problems that the electron beam spot is distorted and the focus characteristics are deteriorated in the upper, lower, left and right peripheral portions of the phosphor screen surface.

The diverging action (concave lens effect) of the deflection yoke acts in such a direction as to cancel the overfocus state of the electron beam spot as the deflection angle of the electron beam increases. Therefore, the shape of the electron beam spot on the phosphor screen surface can be kept in the optimum spot shape in the horizontal direction throughout the entire deflection period. However, in the vertical direction of the electron beam, the focusing action (convex lens effect) by the deflection yoke acts in the direction of increasing the overfocus state of the electron beam spot as the deflection angle of the electron beam increases. as a result,
A long haze portion is generated in the electron beam spot and the resolution is impaired. When the overfocus state in the peripheral portion of the phosphor screen surface is corrected by the dynamic focus method, the electron beam spot is underfocused in the horizontal direction, and an appropriate correction effect cannot be obtained.

In order to solve such a problem, an electron gun for a cathode ray tube equipped with a quadrupole lens is disclosed in, for example, Shoji Sh.
irai, Masakazu Fukushima et al. "Quadrupole Lens f
or Dynamic Focus and Astigmatism Control in an Ell
iptical Aperture Lens Gun ", Proceeding SID 87 DIGE
It is proposed in ST P162-165 (hereinafter referred to as a document) or Japanese Patent Laid-Open No. 3-93135.

[0008]

However, the electron gun for a cathode ray tube equipped with such a conventional quadrupole lens has the following problems. That is, for example, in the electron gun for a cathode ray tube described in the above document, a dynamic quadrupole lens for weakening the main lens action in the peripheral portion of the phosphor screen surface is provided on the cathode side of the main lens. . Further, the control electrode (first grid) is provided with a circular electron beam passage hole. The optical model having such a configuration is used as an optical model of the cathode ray tube electron gun of the related art 1 and shown in FIG.
And (B). In the figure, QP means a quadrupole lens, ML means a main lens, and DY means a deflection yoke. Since a dynamic voltage is applied to the quadrupole lens QP, the quadrupole effect by the quadrupole lens QP does not work for the electron beam impinging on the central portion of the phosphor screen surface (or
It is weak even if it works), but it works strongly for the electron beam that strikes the periphery of the phosphor screen surface. Further, the action of the deflection yoke does not work on the electron beam that strikes the central portion of the phosphor screen surface, but strongly acts on the electron beam that strikes the peripheral portion of the phosphor screen surface. The quadrupole lens QP has a diverging action (concave lens effect) in the vertical direction of the electron beam and a focusing action (convex lens effect) in the horizontal direction.

In such a structure, the distance between the deflection yoke, which is the place where the electron beam distortion occurs, and the quadrupole lens for correcting the electron beam distortion is large. Therefore, the voltage to be applied to the quadrupole lens in order to correct the distortion of the electron beam becomes high, and the load of the correction circuit for operating the quadrupole lens increases. Further, in the peripheral portion of the phosphor screen surface, the aspect ratio of the electron beam spot corrected by the quadrupole lens becomes poor. That is, there is a problem that the horizontal length of the electron beam spot on the phosphor screen surface becomes long and the vertical length becomes short. This is the vertical (vertical) focusing angle and horizontal (horizontal) of the electron beam on the phosphor screen surface.
This is due to the large difference in the focusing angle between the directions (see FIG. 10B). Generally, the length (size) of the electron beam spot is proportional to the reciprocal of the focusing angle.

One of the methods for improving the aspect ratio of the electron beam spot in the peripheral portion of the phosphor screen surface is to make the electron beam passage hole in the control electrode (first grid) elongated. To be An optical model having such a configuration is shown in FIGS. 11A and 11B as an optical model of an electron gun for a cathode ray tube according to the related art 2. When such a method is adopted, the object shape of the electron beam that has passed through the control electrode becomes vertically long, and as a result, the aspect ratio of the electron beam spot in the peripheral portion of the phosphor screen surface is improved ((in FIG. 11). See B)). However, there is a problem that the aspect ratio of the electron beam spot in the central portion of the phosphor screen surface is deteriorated and the electron beam spot shape becomes vertically long (see FIG. 11A).

On the other hand, in the electron gun for a cathode ray tube disclosed in Japanese Patent Laid-Open No. 3-93135, two quadrupole lenses are combined to improve the aspect ratio of the electron beam spot at the time of correction. However, since the two quadrupole lenses are provided on the cathode side of the main lens, there is the same problem as the electron gun for a cathode ray tube described in the above document.
Furthermore, the electron gun for a cathode ray tube disclosed in Japanese Patent Laid-Open No. 3-93135 has the effect of increasing the vertical length of the electron beam spot on the phosphor screen surface, but the horizontal length is not so large. It doesn't get shorter. Therefore, there is a drawback that the resolution of the cathode ray tube is not substantially improved. There is also a problem that the dynamic voltage to be applied to the quadrupole lens increases, the circuit for generating such voltage is burdened, and the manufacturing cost of the cathode ray tube increases.

A vertical bow type convergence error (overconvergence, see FIG. 12) in a conventional deflection yoke having a horizontal deflection magnetic field distribution in a pincushion shape and a vertical deflection magnetic field distribution in a barrel shape is eliminated, and the phosphor screen surface is also eliminated. The applicant of the present invention has proposed a dynamic convergence device capable of reducing the distortion of an electron beam spot in the peripheral part of the device (Japanese Patent Application No. 5-200856, Japanese Patent Application No. 5-200856). 165195).

The dynamic convergence device disclosed in Japanese Unexamined Patent Publication No. 6-165195 is arranged horizontally in a tube of an electron gun for a cathode ray tube, and has a pair of high-voltage side electrode plates facing each other and the pair of high-voltage electrodes. It consists of a pair of low voltage side electrode plates arranged on both outer sides so as to face the side electrode plate, the electron beam passes between the pair of high voltage side electrode plates, and one high voltage side electrode plate and one low voltage side electrode plate Another electron beam passes between the other high-voltage side electrode plate and the other low-voltage side electrode plate.
Further, for example, a parallel circuit of a high resistor and a diode is provided, and the anode of the diode is commonly connected to the low voltage side electrode plate side. On the other hand, the cathodes of the diodes are commonly connected to the high voltage side electrode plate side. Then, a high-voltage DC voltage is applied to the pair of high-voltage side electrode plates, and a vertical parabolic wave voltage is applied to the horizontal retrace line section of the modulated voltage obtained by amplitude modulation by the pseudo-parabolic wave synchronized with the horizontal and vertical deflection periods. The convergence voltage obtained by the addition is commonly supplied to the pair of low voltage side electrode plates through the capacitor.

In the dynamic convergence device having such a configuration disclosed in Japanese Patent Laid-Open No. 6-165195, the magnetic field of the deflection yoke can be a uniform magnetic field in some cases, and the entire phosphor screen surface can be covered. Thus, the convergence error can be corrected and the distortion of the electron beam spot in the peripheral portion of the phosphor screen surface is reduced. Then, the focusing becomes good, the dynamic focus voltage for focusing on the peripheral portion of the phosphor screen surface is small, the convergence can be easily adjusted, the multi-scan monitor can be easily adopted, and the local voltage waveform shaping can be performed. Will be easier.

However, in recent years when the color picture tube, the color display device and the like have become larger and more precise display is required, the dynamic convergence device disclosed in the above-mentioned JP-A-6-165195 and the above-mentioned documents and features. Even if the quadrupole lens disclosed in Kaihei 3-93135 is combined, if a deflection yoke having a horizontal deflection magnetic field distribution in a pincushion shape and a vertical deflection magnetic field distribution in a barrel shape must be used, a phosphor screen In some cases, it may not be possible to sufficiently improve the distortion of the electron beam spot on the surface, and it may not be possible to further improve the resolution of the color cathode ray tube.

Therefore, the object of the present invention is to sufficiently improve the shape and diameter (size) of the electron beam spot over the entire surface of the phosphor screen, and to cover the entire surface of the phosphor screen. An object of the present invention is to provide an electron gun for a cathode ray tube capable of correcting a convergence error and further improving the resolution of the color cathode ray tube.

[0017]

An electron gun for a cathode ray tube according to the present invention for achieving the above object is an electron gun for a cathode ray tube comprising a cathode, an accelerating electrode and a main lens.
(A) Provided between the cathode and the acceleration electrode (second grid) and provided between the control electrode (first grid) having a vertically elongated electron beam passage hole, and (b) provided between the acceleration electrode and the main lens. When the electron beam collides with the peripheral portion of the phosphor screen surface of the cathode ray tube, the first quadrupole has a diverging action (concave lens effect) in the vertical direction of the electron beam and a focusing action (convex lens effect) in the horizontal direction. When the electron beam collides with the central part of the phosphor screen surface of the cathode ray tube, which is provided downstream of the lens and (c) the main lens, the electron beam has a vertical focusing effect (convex lens effect) and a horizontal diverging effect. A second quadrupole lens having a (concave lens effect);
(D) It further comprises a dynamic convergence device provided downstream of the second quadrupole lens.

The quadrupole lens means a means capable of forming a quadrupole electric field for producing the quadrupole effect, and the main lens means a means capable of forming a main lens electric field. . The upstream of the main lens means the cathode side of the main lens, and the downstream of the main lens means the phosphor screen side of the main lens.

In the electron gun for a cathode ray tube of the present invention, the shape of the electron beam passage hole of the acceleration electrode (second grid) may be elongated in some cases.

In the electron gun for a cathode ray tube of the present invention, the dynamic convergence device is arranged horizontally in the tube of the electron gun for a cathode ray tube, and (a) a pair of high voltage side electrode plates facing each other; It consists of a pair of low voltage side electrode plates arranged on both outer sides so as to face the pair of high voltage side electrode plates, the electron beam passes between the pair of high voltage side electrode plates, and one high voltage side electrode plate and one of the high voltage side electrode plates It is preferable to have a structure in which another electron beam passes between the low voltage side electrode plate and another electron beam passes between the other high voltage side electrode plate and the other low voltage side electrode plate.

In the electron gun for a cathode ray tube of the present invention, it is preferable that the first quadrupole lens is composed of a pair of electrode portions, and the second quadrupole lens is also composed of a pair of electrode portions. Further, (a) a high resistance device, (b) a diode connected in parallel to this high resistance device, and (c) a tube body of a cathode ray tube,
Further provided is a clamp circuit composed of a capacitor composed of an outer electrode formed on the outer side of the tube and an inner electrode formed on the inner side of the tube, and one end of the diode is
The second quadrupole lens is electrically connected to one electrode part and the pair of low-voltage side electrode plates of the dynamic convergence device, and the other end of the diode is connected to the other electrode part of the second quadrupole lens and the dynamic part. It is desirable to be electrically connected to the pair of high voltage side electrode plates of the convergence device. As described above, by providing the so-called clamp circuit, the second quadrupole lens and the dynamic convergence device can be appropriately and reliably driven by a simple circuit. Moreover, since a dynamic voltage is supplied to the second quadrupole lens and the dynamic convergence device through the capacitor formed by using the neck glass of the neck portion of the cathode ray tube as a dielectric, a modulation circuit is separately provided and this modulation circuit is used. It is not necessary to directly modulate the high voltage, the circuit configuration can be simplified, and the cost can be significantly reduced.

In this case, the anode which is one end of the diode is electrically connected to one electrode portion of the second quadrupole lens and the pair of low voltage side electrode plates of the dynamic convergence device, while the other end of the diode is connected. Is electrically connected to the other electrode portion of the second quadrupole lens and a pair of high-voltage side electrode plates of the dynamic convergence device, and a high-voltage DC voltage is applied to the other electrode of the second quadrupole lens. Section and a pair of high-voltage side electrode plates, and the vertical parabolic wave voltage is added to the horizontal retrace line section of the modulated voltage obtained by amplitude modulation by the pseudo parabolic wave synchronized with the horizontal and vertical deflection periods. It is preferable to supply the generated voltage to one electrode portion of the second quadrupole lens and the pair of low voltage side electrode plates through a capacitor. With such a configuration, a so-called upper end clamp circuit is configured, and the second quadrupole lens and the dynamic convergence device can be appropriately and reliably driven by a simple circuit. In addition, the degree of modulation of the medium-high voltage focus voltage supplied from the stem side can be reduced, and the cost of the circuit can be reduced.

[0023]

In the electron gun for a cathode ray tube of the present invention whose optical model is shown in FIG. 2, the quadrupole effect of the _first quadrupole lens QP ₁ is minimized at the center of the phosphor screen surface, and the second The quadrupole effect of the quadrupole lens QP ₂ is maximized. The reason for this will be described later. Therefore, in the central portion of the phosphor screen surface, a diverging action (concave lens effect) mainly occurs in the horizontal direction of the electron beam, and a focusing action (convex lens effect) mainly occurs in the vertical direction. As a result, the electron beam spot in the central portion of the phosphor screen surface has a horizontally long spot shape, and as a result, the resolution may not be improved.

As a method for improving the deterioration of the spot shape of the electron beam spot, for example, the electron beam has a focusing function (convex lens effect) in the horizontal direction and a vertical direction in the vertical direction outside the neck portion of the cathode ray tube. A method of correcting with a quadrupole lens having a constant intensity having a diverging action (concave lens effect) can be considered, but in this case, the static convergence changes at the central portion of the phosphor screen surface. Therefore, a method of avoiding the deterioration of the spot shape of the electron beam spot in the central portion of the phosphor screen surface with the quadrupole lens having such a constant strength is, for example, by using the circuit shown in FIG. It is not suitable for the method of supplying a voltage having a relatively easy waveform to the pair of low-voltage side electrode plates of the dynamic convergence device, and it is difficult to obtain the convergence error correction effect and the quadrupole effect at the same time.

However, in the electron gun for a cathode ray tube of the present invention, since the electron beam passage hole of the control electrode (first grid) has a vertically long shape, the object shape of the electron beam passing through the control electrode (first grid) is formed. Becomes portrait. as a result,
The electron beam spot in the central portion of the phosphor screen surface can be made closer to a perfect circle shape from a horizontally long spot shape, and as a result, resolution can be improved (see FIG. 2A).

By adjusting the aspect ratio of the electron beam passage hole constituting the control electrode of the present invention with reference to the conventional control electrode having a circular electron beam passage hole, the horizontal and vertical directions of the electron beam can be adjusted. The object diameter of the beam can be adjusted. That is, when the electron beam passage hole of the control electrode has a circular shape, the sizes (lengths) of the electron beam spot formed on the phosphor screen surface in the vertical direction and the horizontal direction are S _V and S _H , respectively. And On the other hand, by making the control electrode vertically long (non-astigmatic), the vertical and horizontal sizes (lengths) of the object points formed by the electron beam passing through the control electrode are respectively d _V And d _H.

Then, if the aspect ratio of the electron beam passage hole constituting the control electrode is adjusted so that S _V / S _H ≈d _H / d _V , the electron beam spot at the central portion of the phosphor screen surface is adjusted. The shape can be approximated to a perfect circle.

On the other hand, in the peripheral portion of the phosphor screen surface, the quadrupole effect of the _second quadrupole lens QP ₂ disappears, but the horizontal deflection magnetic field distribution is made into a pincushion shape or a weak pincushion shape and vertical deflection is performed. When the deflection yoke DY having a barrel-shaped or weak barrel-shaped magnetic field distribution is provided, the deflection yoke DY forms a quadrupole effect having the same polarity (property) as that of the _second quadrupole lens QP ₂ . Also, the first
The quadrupole effect of the quadrupole lens QP ₁ is maximized. Therefore, the vertically long electron beam that has passed through the main lens ML is corrected by the deflection yoke DY in the direction approaching the perfect circle. However, since the quadrupole effect by the deflection yoke DY is usually quite strong, it is overcorrected and the shape of the electron beam spot on the surface of the phosphor screen becomes slightly horizontal. However,
Compared with a conventional control electrode having an electron beam passage hole having a circular shape (see Prior Art 1), an object point formed by an electron beam passing through the control electrode is vertically long, and therefore, on the phosphor screen surface. The vertical collapse of the electron beam spot is reduced. That is, it is possible to obtain the shape of the electron beam spot that is approximately the same as the optical model of the electron gun for the cathode ray tube of the conventional technique 2 shown in FIG.

Further, in the cathode ray tube electron gun of the present invention, since the dynamic convergence device is provided downstream of the second quadrupole lens, the magnetic field distribution of the deflection yoke can be made more uniform. (That is, it becomes possible to make the horizontal deflection magnetic field distribution a weak pincushion shape and the vertical deflection magnetic field distribution a weak barrel shape), and it is possible to reduce the distortion of the electron beam spot in the peripheral portion of the phosphor screen surface. However, it is possible to correct the convergence error over the entire surface of the phosphor screen.

If necessary, if the shape of the electron beam passage hole of the acceleration electrode (second grid) is made vertically long, the aspect ratio of the electron beam spot at the center of the phosphor screen surface can be controlled more accurately. can do. The aspect ratio of the electron beam passage hole forming the acceleration electrode may be adjusted in the same manner as the control electrode.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

The entire structure of the electron gun for a cathode ray tube of the embodiment of the present invention is shown in FIG. 1 as a schematic end view. FIG.
FIG. 3 is a view of the electron gun for a cathode ray tube viewed from above. The electron gun for a cathode ray tube of the embodiment is, for example, an in-line three-beam type electron gun for a color cathode ray tube, and is arranged at the neck portion 11 of the cathode ray tube 10. Then, in the cathode ray tube electron gun of the embodiment, the cathodes K ₁ , K ₂ and K ₃ are directed toward the phosphor screen surface (not shown) of the cathode ray tube,
A first grid G ₁ ~ sixth grid G _6, the first electrode portions E ₁ and the second electrode portion E ₂ constituting the second quadrupole lens QP ₂ is configured to sequentially position . A deflection yoke (not shown) is arranged in the cathode ray tube downstream of the electron gun for the cathode ray tube.

As shown in FIG. 1, cathodes K ₁ , K ₂ and K ₃ for emitting electron beams for RGB colors are arranged in an in-line three-beam system, that is, in a horizontal straight line.

The _first to sixth grids G ₁ to G ₆ are arranged on the tube axis (Z axis). The first grid G ₁
The 6th grid G ₆ has beam passing holes for passing electron beams, though it may not be given a reference numeral. Depending on the grid, an electrode or an electrode portion is formed by the beam passage hole.

The first grid G ₁ constitutes a control electrode. The second grid G ₂ constitutes an accelerating electrode.
The third grid G ₃ and the fourth grid G ₄ are electrodes for forming the prefocus lens PL. The second grid G ₂ to the fourth grid G ₄ are electrodes having a known structure.

The fifth grid is composed of two grids (a fifth front grid G _5-1 and a fifth rear grid G _5-2 ) and constitutes a focusing electrode for the main lens. The electron beam passage hole, which is the rear electrode portion G _5a of the fifth front grid G _5-1 which is the first focusing electrode, is one of the features of the electron gun for a cathode ray tube of the present invention, the first quadrupole. Lens QP ₁
The electrode part of. Also, the fifth rear grid G
_{Reference numeral 5-2} constitutes a second focusing electrode for the main lens, to which a dynamic focus voltage is applied. The electron beam passage hole, which is the front electrode portion G _5b of the fifth rear grid G _5-2 , constitutes the electrode portion of the _first quadrupole lens QP ₁ .

The sixth grid G ₆ is the final accelerating electrode. The rear electrode part G _5c and the sixth of the fifth rear grid G _5-2
By the front electrode portion G _6a of the grid G ₆ , the main lens ML is
Is configured.

Furthermore, by the first electrode portion E ₁ and the second electrode portion E ₂ , one of the characteristics of the electron gun for a cathode ray tube of the present invention is obtained.
The second quadrupole lens QP _2, which is one of them, is configured.
That is, the first quadrupole lens QP _{1 including a} pair of electrode portions including the electrode portion G _5a and the electrode portion G _5b is provided between the second grid G ₂ which is the acceleration electrode and the main lens ML. Has been. On the other hand, the second quadrupole lens QP _{2 including a} pair of electrode portions including the electrode portions E ₁ and E ₂ is provided downstream of the main lens ML. The first electrode portion E ₁ and the second electrode portion E ₂ are also arranged on the tube axis (Z axis).

Behind (downstream) the _second electrode portion E ₂ , there are provided dynamic convergence devices CP ₁ , CP ₂ , CP ₃ and CP _{4 which} are the features of the electron gun for a cathode ray tube of the present invention. This dynamic convergence device is not a component usually called a convergence cup, but is composed of four parallel plate electrode plates used as a convergence electrode plate in Trinitron (registered trademark). And
The dynamic convergence device is arranged horizontally in the tube of an electron gun for a cathode ray tube.

The dynamic convergence device according to the embodiment includes a pair of high voltage side electrode plates CP ₁ ,
CP ₂ and a pair of low-voltage side electrode plates C arranged on both outer sides of the pair of high-voltage side electrode plates CP ₁ and CP ₂ so as to face each other.
It consists of P ₃ and CP ₄ . And a pair of high voltage side electrode plates C
A central electron beam (green electron beam) passes between P ₁ and CP ₂ , and another electron beam (for example, a red electron beam) passes between one high voltage side electrode plate CP ₁ and one low voltage side electrode plate CP _3. And another electron beam (for example, a blue electron beam) passes between the other high-voltage side electrode plate CP ₂ and the other low-voltage side electrode plate CP ₄ . Tube axes of these electrode plates CP _{1 to} CP ₄ (Z
The length in the (axial) direction is about 10 mm, and the distance between them is about 5 mm.

The second grid G ₂ (accelerating electrode) and the fourth grid G ₄ are connected by a lead wire 12, and the second grid G ₂ and the fourth grid G ₄ accelerate and focus the electron beam. Voltage is supplied for. On the other hand, the third grid G ₃ (which constitutes the prefocus lens PL) and the fifth front grid G _5-1 (which constitutes the first quadrupole lens QP ₁ and the first focusing electrode) respectively lead. It is connected to the DC power supply 14 (focus voltage V _F ) via the line 13. Further, a fifth rear grid G that constitutes the _first quadrupole lens QP ₁ and the main lens ML.
_5-2 is connected to the first dynamic voltage generating circuit 15, and the first dynamic voltage generating circuit 15 is connected to the DC power supply 14. Voltage output from the first dynamic voltage generation circuit 15, a dynamic modulation voltage [Delta] V _F is applied voltage to the voltage V _F, that is, a dynamic focus voltage. Incidentally, for example, V _F is 6 to
On the other hand, ΔV _F dynamically fluctuates within a range of about 1 kV.

As shown in FIG. 1, the sixth grid G ₆ forming the final accelerating electrode and the second electrode portion E ₂ forming the _second quadrupole lens QP ₂ are connected via a lead wire 16. It is electrically connected. The second electrode portion E ₂ is electrically connected to the internal conductive film 18 formed on the inner surface of the cathode ray tube 10 via the connecting member 17 made of an elastic conductive piece. The inner conductive film 18 extends from the neck portion 11 to the funnel portion and is connected to an anode button (not shown). Therefore, the sixth grid G that constitutes the final acceleration electrode
₆ and the second electrode portion E constituting the _second quadrupole lens QP _2.
2 is a high voltage DC voltage (anode voltage H _V , for example 3
0 kV). A pair of high voltage side electrode plates CP ₁ , CP ₂
Are attached to the _second electrode portion E ₂ . Therefore,
An anode voltage H _V , which is a constant high voltage DC voltage, is applied to the pair of high voltage side electrode plates CP ₁ and CP ₂ .

On the other hand, the first electrode portion E ₁ constituting the _second quadrupole lens QP ₂ has a connecting member 2 made of an elastic conductive piece.
It is electrically connected to the neck capacitor 21 via 0. The neck capacitor 21 includes a tubular body (neck glass of the neck portion 11 of the cathode ray tube 10) as a dielectric,
A ring-shaped outer electrode 21A made of a conductive material is formed on the outer side of the tube body, and a ring-shaped inner electrode 21B made of a conductive material is formed on the inner side of the tube body. Then, for example, it is configured to have a capacitance of about several tens of pF. The low voltage side electrode plates CP ₃ and CP ₄ are the first
Is electrically connected to the electrode portion E ₁ .

A high withstand voltage diode (reverse withstand voltage of about 1 KV or more) 22 and a high resistance (of several tens of MΩ) are provided between the first electrode portion E ₁ and the sixth grid G ₆ which is the final acceleration electrode. A resistor (high resistor) 23 is connected in parallel. In the embodiment, the anode corresponding to one end of the diode 22 is electrically connected to the first electrode portion E ₁ which is one of the electrode portions forming the _second quadrupole lens QP ₂ . The first electrode portion E ₁ and the low voltage side electrode plates CP ₃ and C
Since it is electrically connected to P ₄ , the diode 22
The anode corresponding to one end of the above is also electrically connected to the pair of low voltage side electrode plates CP ₃ and CP ₄ of the dynamic convergence device.

On the other hand, the cathode corresponding to the other end of the diode 22 is connected to the second electrode portion E ₂ (the other one constituting the _second quadrupole lens QP ₂₎ via the sixth grid G ₆ and the lead wire 16. (Corresponding to the electrode portion) is electrically connected.
The pair of high voltage side electrode plates CP ₁ and CP ₂ are connected to the second electrode portion E.
Since is attached to _2, the cathode corresponding to the other end of the diode 22 is electrically connected to a dynamic convergence pair of high voltage side electrode plate CP ₁ of the apparatus, CP _2. For example, the resistor 23 can be welded on the low voltage side electrode plate CP ₃ and the diode 22 can be mounted on the low voltage side electrode plate CP ₄ .

As a result, an equivalent circuit as shown in FIG. 3 is constructed. That is, the second dynamic voltage generation circuit 2
4, the neck capacitor 21, the diode 22 and the resistor 23 constitute a so-called upper end clamp circuit. A protective resistor r is connected to the diode 22 in series if necessary. If the internal resistance value of the diode is relatively high, the external protective resistor r is unnecessary. The cathode ray tube electron gun shown in FIG. 1 is not provided with an external resistor r.

In the embodiment, the high voltage DC voltage H _V is applied to the other electrode portion (second electrode portion E ₂ ) of the second quadrupole lens.
And a pair of high voltage side electrode plates CP ₁ and CP ₂ and a vertical parabolic wave voltage is applied to the horizontal retrace line section of the modulated voltage obtained by amplitude modulation by the pseudo parabolic wave synchronized with the horizontal and vertical deflection periods. The voltage obtained by the addition is passed through the capacitor 21 to one electrode portion (first electrode portion E ₁ ) of the second quadrupole lens and the pair of low voltage side electrode plates CP ₃ and CP ₄
Supply to.

Specifically, in the embodiment, as a waveform of the dynamic voltage output from the second dynamic voltage generating circuit 24, for example, as shown in FIG. A voltage having a pseudo-parabolic waveform synchronized with the horizontal and vertical deflection periods is used by superimposing a pulse waveform on the (ranking section). That is, first, the modulated voltage is obtained by amplitude-modulating the pseudo parabolic wave synchronized with the horizontal and vertical deflection periods (see FIG. 4A). The absolute value of the amplitude of this modulated voltage is V _QP (for example, 1 kV). Then, by adding the vertical parabolic wave voltage to the horizontal retrace line section of this modulated voltage, the voltage changing between 0 (V) and −V _QP (V) as shown in FIG. Obtainable. The voltage is output from the second dynamic voltage generation circuit 24. The waveform of the voltage V _QP shown in FIG. 4B is a waveform in which the clamp pulse CP amplitude-modulated with the vertical periodic waveform is inserted in the horizontal retrace line section of the voltage waveform shown in FIG. 4A. Is. Within the horizontal return section,
Since the operation of the second quadrupole lens and the correction of the convergence are unnecessary, there is no problem even if the clamp pulse CP is inserted.

For the outer electrode 21A of the neck capacitor 21, the modulation voltage 0 (synchronized with the deflection cycle) shown in FIG. 4B is supplied from the second dynamic voltage generating circuit 24 provided outside the cathode ray tube 10. V) to −V _QP (V) are supplied. The second dynamic voltage generating circuit 24, the neck capacitor 21, the diode 22 and the resistor 23 constitute an upper end clamp circuit, and one end of the upper end clamp circuit is connected to the anode voltage H from the second electrode portion E _2. since _V is supplied, is applied to a first waveform of the voltage applied to the electrode unit E _1, and the first electrode portion E ₁ and the low-voltage side electrode plate CP ₃ that are electrically connected, CP ₄ The voltage waveform of the anode voltage H _V
Upper end is clamped to a waveform that varies between H _V ~H _V -V _'QP.

Thus, the voltage applied to the first electrode portion E ₁ is modulated as shown in FIG. 4 (C). Also,
As shown in FIG. 4C, the low-voltage side electrode plates CP ₃ and CP ₄ are also supplied with the modulation voltages H _{V to} H _V −V ′ _QP synchronized with the deflection period, as convergence correction voltages.

Incidentally, this waveform may be deformed if necessary, and as shown in FIG. 4B, it is not always necessary to clamp the upper end at 0 (V). However, if the upper end clamp circuit is not provided, the waveform of the voltage applied to the low-voltage side electrode plates CP ₃ and CP ₄ is simply an AC-coupled waveform as shown in FIG. In this case, the vertical cycle component of the modulation voltage synchronized with the deflection cycle is not faithfully transmitted. Alternatively, the voltage applied to the first electrode portion E ₁ may be higher than the voltage applied to the _second electrode portion E ₂ forming the second quadrupole lens. In the case of the second quadrupole lens QP
_The desired quadrupole effect due to ₂ cannot be obtained. On the other hand, by providing an upper end clamp circuit as shown in the equivalent circuit of FIG. 3, the peak voltage value of the clamp pulse CP is clamped to the high voltage DC voltage (anode voltage) H _V as shown in FIG. 4C. Therefore, the voltage applied to the first electrode portion E ₁ and the low-voltage side electrode plates CP ₃ and CP ₄ is suppressed to a portion higher than the high-voltage DC voltage H _V and is pushed down to the negative side. As a result, a dynamic voltage varying from H _V to H _V −V ′ _{QP is generated} in the first electrode portion E ₁ and the low voltage side electrode plate C.
It is surely applied to P ₃ and CP ₄ .

The voltage applied to the capacitor 21 is as shown in FIG.
The voltage may be an AC-coupled voltage as shown in (D). Also in this case, a voltage whose upper end is clamped to the anode voltage H _V is applied to the first electrode portion E ₁ and the low voltage side electrode plates CP ₃ and CP ₄ .

A second capacitor is formed through the capacitor 21 having the neck glass of the neck portion 11 of the cathode ray tube 10 as a dielectric.
Since a dynamic voltage can be supplied to the first electrode portion E ₁ and the low-voltage side electrode plates CP ₃ and CP ₄ which form the quadrupole lens QP ₂ of FIG. Need not be directly modulated.

FIG. 5 schematically shows the planar shape of the electrode portion of each grid in the example. In the embodiment, the electron beam passage hole, which is an electrode in the first grid G ₁ forming the control electrode, has a vertically long shape (see FIG. 5A). Further, the electron beam passage hole, which is an electrode in the second grid G ₂ forming the acceleration electrode, is composed of a substantially circular opening (see FIG. 5B).

Further, the rear electrode portion G _5a of the fifth front grid G _5-1 forming the _first quadrupole lens QP ₁ has a vertically long rectangular shape, as schematically shown in FIG. 5 (C). Have a shape. On the other hand, the front electrode portion G _5b of the fifth rear grid G _5-2 which constitutes the _first quadrupole lens QP ₁ has a horizontally long rectangular shape, as schematically shown in FIG. .

In the embodiment, the fifth rear grid G
The front electrode part G _5b of _5-2, a fifth voltage applied to the rear electrode portions G _5a of the front grid G _5-1 (V _F) or dynamic voltage _{(V F + ΔV F, V} F + ΔV _{F1 to} V _F + Δ
Varying between V _F2 ) is applied. V _F and (V _F + Δ
The waveform of V _F ) is shown in FIG. 6, and ΔV _F has a pseudo parabolic waveform. As a result, the first quadrupole lens QP ₁ has a diverging action (concave lens effect) in the vertical (vertical) direction and a horizontal (horizontal) action.
A non-axisymmetric so-called quadrupole effect having a focusing effect (convex lens effect) in the direction occurs. This state is schematically shown in FIG.

In horizontal scanning, the phosphor screen surface
For the electron beam impinging on the central part,
Dead G_5-1Voltage (V_F) And the fifth rear grip
De G _5-2Voltage (V_F+ ΔV_F) Is
Minimum (ΔV_F1), The first quadrupole lens QP₁
Has the lowest quadrupole effect. Also, the phosphor screen surface
To the electron beam moving from the central part of the
Then, the 5th front grid G_5-1Voltage applied to
(V_F) And the fifth rear grid G_5-2Voltage applied to
(V_F+ ΔV_F), The potential difference between
Polar lens QP₁Quadrupole effect is increased. The fifth rear
Grid G_5-2Applied to the sixth grid G₆To
Since the potential difference from the applied voltage decreases, the main lens M
The main lens action of L is weakened. Furthermore, the phosphor screen surface
The electron beam that strikes the periphery of the
Lid G_5-1Voltage (V_F) And the fifth rear green
Dead G_5-2Voltage (V_F+ ΔV_F) And the potential difference
Is the maximum (ΔV_F2), The first quadrupole lens QP
₁The quadrupole effect of is maximal.

Further, the first electrode portion E ₁ and the second electrode portion E ₂ constitute the _second quadrupole lens QP ₂ , which is one of the features of the electron gun for a cathode ray tube of the present invention. There is.
The shape of the first electrode portion E ₁ is schematically shown in a perspective view in FIG. The first electrode portion E ₁ is provided with an opening which is an electron beam passage hole, and the projection E _1a is provided above and below this opening. The protrusion E _1a extends like an eaves toward the _second electrode portion E ₂ .
On the other hand, the shape of the second electrode portion E ₂ is schematically shown in FIG. Note that FIG. 8B is a view of the second electrode portion E ₂ and the first electrode portion E ₁ viewed from the phosphor screen surface side, and the eave-shaped protrusion of the _first electrode portion E ₁ The portion E _1a extends through the substantially rectangular opening (electron beam passage hole) of the second electrode portion E ₂ .

In the embodiment, the voltage applied to the _first electrode portion E ₁ is the same as that of the sixth grid G ₆ and the second electrode portion E _2.
Is less than or equal to the voltage applied to. Therefore, the second quadrupole lens QP ₂ has a focusing action (convex lens effect) in the vertical (vertical) direction and a diverging action (concave lens effect) in the horizontal (horizontal) direction with respect to the electron beam, and is not axisymmetric. The quadrupole effect of occurs.

In the horizontal scanning, with respect to the electron beam impinging on the central portion of the phosphor screen surface, the voltage applied to the _first electrode portion E ₁ and the sixth grid G ₆ and the second grid portion G ₆ are applied. Since the potential difference from the voltage applied to the electrode portion E ₂ is maximum (for example, V ′ _QP , see FIG. 4C), the second
The quadrupole effect of the quadrupole lens QP ₂ is maximized. Further, for the electron beam moving from the central portion to the peripheral portion of the phosphor screen surface, the voltage applied to the _first electrode portion E ₁ , the sixth grid G ₆ and the second electrode portion E ₂ are applied. Since the potential difference with the voltage applied to the second quadrupole lens QP ₂ decreases, the quadrupole effect of the _second quadrupole lens QP ₂ decreases (see (C) of FIG. 4) and collides with the peripheral portion of the phosphor screen surface. With respect to the electron beam, the potential difference between the voltage applied to the first electrode portion E ₁ and the voltage applied to the sixth grid G ₆ and the second electrode portion E ₂ is eliminated, so that the second quadruple The quadrupole effect of the polar lens QP ₂ disappears.

Further, in the vertical scanning, with respect to the electron beam impinging on the central portion of the upper end of the phosphor screen surface, the voltage applied to the _first electrode portion E ₁ , the sixth grid G ₆ and the The maximum value of the potential difference from the voltage applied to the _second electrode portion E ₂ is small, and the potential difference of the applied voltage is maximum (−V ′ _QP ) at the central portion in the vertical direction of the phosphor screen surface.
Becomes Therefore, rather than the upper and lower ends of the phosphor screen surface,
The quadrupole effect of the _second quadrupole lens QP ₂ becomes larger at the central portion in the vertical direction of the phosphor screen surface.

An optical model of the first quadrupole lens QP ₁ , the main lens ML, the second quadrupole lens QP ₂ and the deflection yoke DY in the electron gun for a cathode ray tube of the above-described embodiment is shown in FIG. Shown in (A) and (B). The optical model shown in FIG. 2A is an optical model when the electron beam collides with the central portion of the phosphor screen surface. On the other hand, the optical model shown in FIG. 2B is an optical model when the electron beam collides with the peripheral portion of the phosphor screen surface.

As shown in FIG. 2A, when the electron beam impinges on the central portion of the phosphor screen surface, the quadrupole effect of the _first quadrupole lens QP ₁ is minimum, The quadrupole effect of the _second quadrupole lens QP ₂ is maximum, and the quadrupole effect of the deflection yoke DY does not reach such an electron beam. Since the electron beam passage hole of the first grid G ₁ which is the control electrode has a vertically long shape, the object point shape of the electron beam having passed through the control electrode is vertically long. Therefore, the spot shape of the electron beam at the center of the phosphor screen surface approaches a perfect circle.

On the other hand, as shown in FIG. 2B, when the electron beam collides with the peripheral portion of the phosphor screen surface,
The quadrupole effect of the _first quadrupole lens QP ₁ is maximum,
The quadrupole effect of the _second quadrupole lens QP ₂ has disappeared, and the quadrupole effect of the deflection yoke DY is maximum. Normal,
Since the quadrupole effect by the deflection yoke is quite strong, it is overcorrected and the shape of the electron beam spot on the surface of the phosphor screen becomes slightly horizontal. However, as compared with a conventional control electrode having an electron beam passage hole having a circular shape, the vertical direction of the electron beam spot on the phosphor screen surface is increased because the object point formed by the electron beam passing through the control electrode is vertically long. Collapse of direction is reduced.

Further, the dynamic convergence can be surely performed by the dynamic convergence device. That is, for the electron beam impinging on the central portion of the phosphor screen surface, the high voltage side electrode plates CP ₁ , CP ₂
A strong electric field is formed by the low-voltage side electrode plates CP ₃ and CP ₄ . On the other hand, with respect to the electron beam that collides with the peripheral portion of the phosphor screen surface, it collides with the central portion of the phosphor screen surface by the high-voltage side electrode plates CP ₁ and CP ₂ and the low-voltage side electrode plates CP ₃ and CP ₄ . A weaker electric field is created than for the electron beam. Therefore, the convergence error can be corrected over the entire surface of the phosphor screen. Therefore, even if a conventional deflection yoke having a horizontal deflection magnetic field distribution in a pincushion shape and a vertical deflection magnetic field distribution in a barrel shape is used, each magnetic field distribution intensity can be reduced and the fluorescence of the cathode ray tube can be reduced. It is possible to suppress deterioration of focus in the peripheral portion of the body screen surface. At the center of the phosphor screen surface, there is a potential difference between the high-voltage side electrode plates CP ₁ and CP ₂ and the low-voltage side electrode plates CP ₃ and CP ₄ that make up the dynamic convergence device. The static convergence of the electron gun itself must be set in consideration of this potential difference.

In the electron gun for a cathode ray tube of the present invention, as shown in the schematic plan view of FIG. 9A, an electron beam passage hole which is an electrode in the second grid G ₂ which constitutes an acceleration electrode. The shape may be vertically long. Further, the vertically long shapes (non-dotted holes) of the control electrode (first grid G ₁ ) and the acceleration electrode (second grid G ₂ ) are the rectangles shown in FIG. 2A and FIG. 9A. The shape is not limited to the elliptical shape (see FIG. 9B) or the elliptical shape (see FIG. 9C).

The present invention has been described above based on the preferred embodiment, but the present invention is not limited to this embodiment. The first quadrupole lens QP ₁ and the second quadrupole lens Q
The structure of the electrode portion of P ₂ is not limited to the structure described in each embodiment, and can be changed as appropriate. Further, the numerical values given in the examples are mere examples and can be changed as appropriate.

In the embodiment, the focus voltage V _F for forming the main lens ML is dynamically modulated (Δ
V _F ). This makes it possible to optimize the electron beam spot shape at each position on the phosphor screen surface. In this case, the first dynamic voltage generating circuit 15 and the outer electrode 21A of the neck capacitor 21 are directly connected to each other, and the output voltage (V _F + ΔV _F ) from the first dynamic voltage generating circuit 15 is supplied to the first electrode portion E. If it is configured to supply to the _first dynamic voltage generation circuit 2
4 can be omitted. Alternatively, for example, a dynamic voltage for operating the _second quadrupole lens QP ₂ and the low voltage side electrode plates CP ₃ and CP ₄ of the dynamic convergence device is supplied from a coaxial button provided in the funnel portion via a coaxial cable. It may be configured to do so.

Second quadrupole lens QP ₂ in the embodiment
The structures of the first electrode portion E ₁ and the second electrode portion E ₂ constituting the above are changed to, for example, shapes similar to those shown in the schematic plan views of FIGS. 5C and 5D, respectively. be able to. That is, the first electrode portion E ₁ has a horizontally long rectangular electron beam passage hole. On the other hand, the second electrode portion E ₂ has a vertically long rectangular electron beam passage hole. The voltage applied to the first electrode portion E ₁ is less than or equal to the voltage applied to the sixth grid G ₆ and the second electrode portion E ₂ . Therefore, with such an electrode structure, the second quadrupole lens Q
A non-axisymmetric quadrupole effect having a focusing action (convex lens effect) in the vertical (vertical) direction and a diverging action (concave lens effect) in the horizontal (horizontal) direction with respect to the electron beam occurs in P ₂ .

The cathode ray tube electron gun of the present invention can be applied to a bipotential type or unipotential type electron gun.

[0071]

As described above, in the electron gun for a cathode ray tube of the present invention, a quadrupole lens is arranged upstream and downstream of the main lens ML, and the electron beam passage hole of the control electrode is formed in a vertically long shape. By doing so, the electron beam spot striking the central portion of the phosphor screen surface can be made closer to a perfect circle, and the resolution of the cathode ray tube can be improved. Furthermore, since the correction effect of the electron beam spot shape by the quadrupole lens is enhanced, the dynamic voltage to be applied to the quadrupole lens can be reduced,
The dynamic voltage generating circuit can be simplified and the cost can be reduced.

In addition, according to the electron gun for a cathode ray tube of the present invention, since the electron beam spot approaches a perfect circle, deterioration of resolution in the horizontal direction and luminance saturation of the phosphor are prevented, and color purity due to luminance saturation is reduced. It is possible to solve problems in the prior art such as deterioration, interference with the color selection mechanism due to the size of the electron beam spot in the vertical direction being too small, and the effect of improving white uniformity. is there.

Further, in the electron gun for a cathode ray tube of the present invention, since the dynamic convergence device is provided downstream of the second quadrupole lens, the distortion of the horizontal deflection magnetic field and the vertical deflection magnetic field can be reduced. , It becomes possible to reduce the distortion of the electron beam spot in the peripheral portion of the phosphor screen surface caused by the pincushion-shaped horizontal deflection magnetic field distribution or the barrel-shaped vertical deflection magnetic field distribution in the conventional deflection yoke, and Convergence error can be corrected over the entire screen surface.

[Brief description of drawings]

FIG. 1 is a schematic view showing an entire electron gun for a cathode ray tube of an embodiment.

FIG. 2 is a diagram showing an optical model of a _first quadrupole lens QP ₁ , a main lens ML, a second quadrupole lens QP ₂ and a deflection yoke DY.

FIG. 3 is a diagram showing an equivalent circuit of a second quadrupole lens and a dynamic convergence device of an example.

FIG. 4 is a voltage waveform diagram for a second quadrupole lens and a dynamic convergence device of an example.

FIG. 5 is a diagram schematically showing a planar shape of an electrode portion of each grid in the example.

FIG. 6 is a voltage waveform diagram for the first quadrupole lens of the example.

FIG. 7 is a schematic diagram for explaining the operation of a quadrupole lens.

FIG. 8 is a diagram schematically showing an electrode portion forming a second quadrupole lens in an example.

FIG. 9 is a schematic plan view showing a modification of a control electrode (first grid G ₁ ) and an acceleration electrode (second grid G ₂ ).

FIG. 10 is a diagram showing an optical model of an electron gun for a cathode ray tube of prior art 1.

FIG. 11 is a diagram showing an optical model of an electron gun for a cathode ray tube of prior art 2.

FIG. 12 is a diagram for explaining a convergence error.

[Explanation of symbols]

K ₁ , K ₂ , K ₃ cathode G ₁ 1st grid (control electrode) G ₂ 2nd grid (accelerating electrode) G ₃ 3rd grid (prefocus lens) G ₄ 4th grid (prefocus lens) G _{5- 1} Fifth front grid (first focusing electrode) G _5a Rear electrode of fifth front grid (constituting first quadrupole lens) G _5-2 Fifth rear grid G _5b Front electrode part of fifth rear grid G _5c Rear electrode part of the 5th rear grid G ₆ 6th grid G _6a Front electrode of the 6th grid (constitutes the main lens) E ₁ 1st electrode part (constitutes the second quadrupole lens) E ₂ 2 electrode part (constituting second quadrupole lens) ML main lens QP ₁ first quadrupole lens QP ₂ second quadrupole lens CP ₁ , CP ₂ , CP ₃ , CP ₄ dynamic convergence device 10 cathode ray tube 11 neck part 12 lead wire 13 lead 14 DC power supply 15 first dynamic voltage generation circuit 16 leads 17 connecting member 18 internal conductive coating 20 connecting member 21 neck capacitor 22 diode 23 resistor 24 second dynamic voltage generating circuit

Claims (3)

[Claims] 1. An electron gun for a cathode ray tube comprising a cathode, an accelerating electrode and a main lens, comprising: (a) a control provided between the cathode and the accelerating electrode and having a vertically elongated electron beam passage hole. Electron beam (b) Provided between the accelerating electrode and the main lens. When the electron beam collides with the peripheral part of the phosphor screen surface of the cathode ray tube, the electron beam diverges vertically and horizontally. (1) is provided downstream of the main lens and has a focusing action in the vertical direction of the electron beam when the electron beam collides with the center of the phosphor screen surface of the cathode ray tube, An electron gun for a cathode ray tube, further comprising a second quadrupole lens having a diverging action in a direction, and (d) a dynamic convergence device provided downstream of the second quadrupole lens. . 2. The electron gun for a cathode ray tube according to claim 1, wherein the electron beam passage hole of the accelerating electrode is vertically long. 3. The dynamic convergence device comprises:
It is arranged horizontally in the tube of the electron gun for a cathode ray tube. A pair of low voltage side electrode plates, an electron beam passes between the pair of high voltage side electrode plates, and another electron beam passes between one high voltage side electrode plate and one low voltage side electrode plate, The electron gun for a cathode ray tube according to claim 1, wherein another electron beam passes between the other high-voltage side electrode plate and the other low-voltage side electrode plate.