JPH10172465A - Electron gun for inline three-beam type cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inline three-beam type cathode-ray tube having favorable resolution characteristics in which a spot form of an electron beam colliding with a peripheral part of a phosphor screen surface can be roughly round. SOLUTION: An electron gun for an inline three-beam type cathode-ray tube is provided with a static deflection plate 16 comprising two convergence shield plates 17, and convergence plates 18 disposed out on the right and left of the convergence shield plates 17, and a phosphor screen surface side end part 18A of each convergence plate 18 is protruded more on the phosphor screen surface side than a phosphor screen surface side end part 17A of the convergence shield plute 17, and convergence shield parallel plates 19 are disposed at the phosphor screen surface side end part 17A of the convergence shield plate 17 above and under three electron beams to have them between them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electron gun for an in-line three-beam type cathode ray tube.

[0002]

2. Description of the Related Art In a conventional color cathode ray tube, a schematic diagram of which is shown in FIG. 12, the resolution characteristic generally depends greatly on the size and shape of an electron beam spot on a phosphor screen. That is, unless the spot diameter of the electron beam is small and close to a perfect circle, good resolution characteristics cannot be obtained.

[0003] As the deflection angle of the electron beam increases, the trajectory of the electron beam from the electron gun for a cathode ray tube to the phosphor screen increases. Therefore, if the focus voltage is maintained such that a small-diameter and perfect circular electron beam spot shape is obtained at the central portion of the phosphor screen surface, the peripheral portion of the phosphor screen surface is in an overfocus state (FIG. 13). See schematic diagram). As a result, an electron beam spot shape with a small diameter and a perfect circle cannot be obtained at 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 increases, that is, with respect to the electron beam colliding with the peripheral portion of the phosphor screen surface, the focus voltage is increased and the dynamic focus effect of weakening the main lens effect is obtained. Electron guns for cathode ray tubes have been devised. However, in this dynamic focus method alone, R,
Even if an optimum focus on the phosphor screen surface can be obtained for each of the electron beams of G and B colors, deviation of the convergence occurs when the electron beam is deflected to the periphery of the phosphor screen surface. come. That is, 3
In-line 3 with two cathodes arranged on a horizontal straight line
In a conventional beam type electron gun for a cathode ray tube, if the deflection magnetic field of the deflection yoke is a uniform magnetic field, even if the convergence is performed at the center of the phosphor screen surface, the vertical portions at the upper, lower, left, and right peripheral portions of the phosphor screen surface are vertical. An arcuate convergence error (overconvergence) occurs.

Therefore, conventionally, dynamic convergence has been performed by setting the horizontal deflection magnetic field distribution by the deflection yoke to a pincushion shape and the vertical deflection magnetic field distribution to a barrel shape. However, when a non-uniform magnetic field deflection yoke having such a configuration is used, the electron beam passing through the deflection yoke and deflected toward the periphery of the phosphor screen surface is schematically shown in FIG. In the vertical direction (longitudinal direction, Y direction), it receives a convergence effect (convex lens effect), and in the horizontal direction (horizontal direction, X direction), it receives a diverging effect (concave lens effect). As a result, the spot shape of the electron beam at the peripheral portion of the phosphor screen surface is not a perfect circle but a horizontally long shape. Therefore, at the left and right peripheral portions of the phosphor screen surface, there is a problem that the spot shape of the electron beam is distorted and the focus characteristic is deteriorated.

In order to solve such a problem, an electron gun for a cathode ray tube having a quadrupole lens for forming a so-called electrostatic quadrupole (hereinafter simply referred to as a quadrupole) electric field is known. FIG. 4A shows a high unipotential focus (H) incorporating a generally widely used quadrupole lens.
FIG. 1 shows a conceptual diagram of an electron gun for a color cathode ray tube of the (UPF) type. This color cathode ray tube electron gun has three cathodes 1
0, a first electrode 11, a second electrode 12, an intermediate electrode 12A, a third electrode 13, a fourth electrode 14, a fifth electrode 15, and an electrostatic deflecting plate 16. And the first electrodes 11 to 11
A prefocus lens system is formed by the intermediate electrode 12A. On the other hand, the third electrode 13 to the fifth electrode 15 form a main focus lens system. Here, the fourth electrode 1
4A is a schematic perspective view of FIG. 5A and FIG. 5B is a schematic plan view of the _{fourth_1} electrode 14.
A, the _{fourth_2_electrode} 14B, and the _{fourth_3} electrode 14C.

In this electron gun for a color cathode ray tube,
As shown in FIG. 4B, a high anode voltage _VA is applied to the third electrode 13 and the fifth electrode 15 via an anode button (see FIG. 12). On the other hand, the fourth _{_2} electrode 14
B has a constant focus voltage V via a stem pin.
_F is applied. Further, the _{fourth_1} electrode 14A and the _{fourth_1_3}
The electrodes 14C, the focus voltage V parabolic voltage in synchronization with the horizontal deflection of the _F V _P and the focus voltage V _F and is superimposed dynamic focusing voltage V _DF (V _F + V _P) is applied (see FIG. 7). In FIG. 4B, “C
"S" means convergence shield plate, "CP"
Means convergence plate.

As shown in a schematic perspective view in FIG. 6, the electrostatic deflecting plate 16 includes two convergence shield plates 1.
7 and a convergence plate 18 arranged on the left and right outer sides of the convergence shield plate 17. FIG. 6 is a partial view of the electrostatic deflecting plate 16 viewed from the phosphor screen surface side. The anode voltage _VA is applied to the convergence shield plate 17. On the other hand, a voltage of about 95% of the anode voltage _VA is applied to the convergence plate 18. by this,
As shown in the schematic diagram of FIG. 6B, the electron beam (indicated by a black circle) passing through the space between the convergence shield plate 17 and the convergence plate 18 of the electrostatic deflection plate 16 is 2. It is bent in the direction of the electron beam passing through the space between the convergence shield plates 17.

[0009] When the electron beam strikes the right and left end portions of the fluorescent screen, as shown in FIG. 7, the fourth _{_1} electrode 14
A and the potential of the fourth _{_3} electrode 14C (V _DF) fourth _{_2} electrode 1
It becomes higher than the potential (V _F ) of 4B. On the other hand, the difference between the potential (V _DF ) of the _{fourth_3} electrode 14C and the potential (V _A ) of the fifth electrode 15 becomes small. As a result, the intensity of the focus lens formed between the fourth electrode 14 and the fifth electrode 15 is changed, and as a result, the electron beam that collides with the left and right ends of the phosphor screen surface has the focus of the main focus lens system. The distance becomes longer, and a dynamic focus effect can be obtained. The fourth electrode 14 forms a quadrupole lens. In this quadrupole lens, the quadrupole lens effect acts strongly on the electron beam that collides with the left and right ends of the phosphor screen surface, and the electron beam passing through the fourth electrode 14 is directed in the vertical direction ( A divergent effect (concave lens effect) is exerted in the vertical direction and the Y direction, while a focusing effect (convex lens effect) is exerted in the horizontal direction (lateral direction and the X direction) (see the schematic diagram of FIG. 8). As a result, the quadrupole lens effect exerted by the deflection yoke on the electron beam deflected toward the periphery of the phosphor screen surface is canceled, and the spot shape of the electron beam at the periphery of the phosphor screen surface becomes a perfect circle. Approach. When the electron beam collides with the central portion of the phosphor screen surface, the quadrupole lens effect by the fourth electrode 14 and the deflection yoke does not occur, and the electron gun for a cathode ray tube operates as a normal unipotential focus lens. I do.

[0010]

However, in the cathode ray tube electron gun having the structure shown in FIG. 4, the deflection yoke and the fourth electrode 14 are arranged at a certain distance in the tube axis direction (Z direction). Have been. Therefore, as shown in the optical model in FIG. 9, when the electron beam collides with the peripheral portion of the phosphor screen surface, the imaging magnification in the vertical direction is M.
_As compared with _Y (= b _Y / a _Y ), the imaging magnification M _X (= b
_X / a _X ) is larger, and the spot shape of the electron beam colliding with the peripheral portion of the phosphor screen surface is horizontally long. In this state, and when the electron beam collides with the center of the phosphor screen, the spot shape of the electron beam is shown in FIG.
Is shown schematically in FIG.

Accordingly, an object of the present invention is to provide an in-line three-beam type electron gun for a cathode ray tube, which can make the spot shape of an electron beam impinging on the peripheral portion of the phosphor screen surface close to a perfect circle and has good resolution characteristics. To provide.

[0012]

In order to achieve the above object, an electron gun for an in-line three-beam type cathode ray tube according to the present invention comprises (a) a cathode, (b) a prefocus lens system, and (c) a main focus. The lens system is provided with (d) two convergence shield plates, and an electrostatic deflecting plate including a convergence plate disposed on the left and right outer sides of the convergence shield plates. The end of each convergence plate on the phosphor screen side projects toward the phosphor screen side from the end of the convergence shield plate on the phosphor screen side, and the end of the convergence shield plate on the phosphor screen side. Is characterized in that a convergence shield parallel plate is disposed at a position sandwiching the three electron beams vertically.

In the electron gun for an in-line three-beam type cathode ray tube according to the present invention, a quadrupole electric field is formed by the protruding portion of the convergence plate and the parallel plate of the convergence shield, and the electron beam is elongated vertically by the quadrupole electric field. It is preferable to mold it into

In the electron gun for an in-line three-beam type cathode ray tube of the present invention, it is preferable that a quadrupole electrode for forming a quadrupole electric field is incorporated in the main focus lens system. It is preferable that the electron beam colliding with the central portion of the phosphor screen surface by the quadrupole electric field be shaped horizontally.

In the electron gun for an in-line three-beam type cathode ray tube according to the present invention, by providing the projected portion of the convergence plate and the parallel plate of the convergence shield, it is possible to form a quadrupole electric field in a space surrounded by these. As a result, the distance between the deflection yoke and the quadrupole electric field can be reduced. As a result, as shown in the optical model in Figure 3, the lateral imaging magnification M _X when the electron beam to the peripheral portion of the fluorescent screen is collision approaches the longitudinal direction of the imaging magnification M _Y, The spot shape of the electron beam colliding with the periphery of the phosphor screen surface approaches a perfect circle. The quadrupole electric field formed in the space surrounded by the protruding portion of the convergence plate and the convergence shield parallel plate is referred to as a quadrupole electric field in the electrostatic deflection plate for convenience.

When the electron beam collides with the central part of the phosphor screen, the quadrupole lens effect by the deflection yoke does not occur. Therefore, the spot shape of the electron beam that collides with the central portion of the phosphor screen surface due to the quadrupole electric field in the electrostatic deflection plate becomes vertically long. However, if a quadrupole electrode for forming a quadrupole electric field is incorporated in the main focus lens system, and the electron beam colliding with the central portion of the phosphor screen surface by this quadrupole electric field is shaped horizontally, the phosphor can be obtained. The spot shape of the electron beam colliding with the center of the screen surface approaches a perfect circle. The built-in quadrupole electrode for forming a quadrupole electric field in the main focus lens system is a quadrupole lens in the fourth electrode 14 of the conventional color cathode ray tube electron gun whose optical model is shown in FIG. The effect has the opposite quadrupole lens effect.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings based on embodiments of the invention (hereinafter abbreviated as embodiments).

The structure of the electron gun for the in-line three-beam type cathode ray tube in the embodiment, except for the structure of the electrostatic deflection plate, is basically the conventional high unipotential focus (H-UPF) shown in FIGS. The structure was the same as that of the in-line three-beam type electron gun for a cathode ray tube. That is, the electron gun for an in-line three-beam cathode ray tube according to the present invention comprises three cathodes 10, a first electrode 11, and a second electrode 1.
2, an intermediate electrode 12A, a third electrode 13, a fourth electrode 14, a fifth electrode 15, and an electrostatic deflecting plate 16.
Then, a prefocus lens system is formed by the first electrode 11 to the intermediate electrode 12A. On the other hand, the third electrodes 13 to
The fifth electrode 15 forms a main focus lens system. Here, the fourth electrode 14, in FIG. 5 (A) shows a schematic perspective view, as shown in the schematic plan view in FIG. 5 (B), fourth _{_1} electrode 14A, the fourth _{_2} electrode 14B, is composed of three electrodes of the fourth _{_3} electrode 14C (quadrupole electrodes for forming a quadrupole field).

In the electron gun for a color cathode ray tube according to the embodiment, as shown in FIG.
An anode button is applied to the third and fifth electrodes 15 (see FIG. 12).
, _A high anode voltage _VA is applied. on the other hand,
The fourth _{_2} electrode 14B, through the stem pins, fixed focus voltage V _F is applied. Further, the _{fourth_1} electrode 1
4A and fourth _{_3} electrode 14C, a dynamic focus voltage obtained by subtracting the parabolic voltage V _P which is synchronized with the horizontal deflection of the focus voltage V _F from the focus voltage V _F V _DF (V _F -
_VP ) is applied (see FIG. 2). This point is different from the dynamic focus voltage V _DF in conventional in-line three-beam method electron gun for a cathode ray tube shown in FIG.

[0020] When the electron beam strikes the right and left end portions of the fluorescent screen, as shown in FIG. 2, 4th _{_1} electrode 14
A and the potential of the fourth _{_3} electrode 14C (V _DF) fourth _{_2} electrode 1
It approaches the potential (V _F ) of 4B. In addition, the _{fourth_3} electrode 14C
The difference between the potential (V _DF ) and the potential (V _A ) of the fifth electrode 15 becomes smaller. Thus, the fourth electrode 14 and the fifth electrode 15
As a result, the focal length of the main focus lens system becomes longer for an electron beam that collides with the left and right ends of the phosphor screen surface, thereby obtaining a dynamic focus effect. it can. Further, the quadrupole lens is not formed by the fourth electrode 14.

On the other hand, when the electron beam collides with the central portion of the phosphor screen, as shown in FIG. 2, the potentials (V _DF ) of the 4 _{_1} electrode 14A and the 4 _{_3} electrode 14C are changed to the 4 _{_2} electrode 14B. (V _F ). Further, the potential (V _DF ) of the _{fourth_3} electrode 14C and the potential (V _A ) of the fifth electrode 15
The difference becomes large. Thereby, the fourth electrode 14 and the fifth electrode 14
As a result of a change in the intensity of the focus lens formed between the electrode and the electrode 15, the focal length of the main focus lens system is reduced with respect to the electron beam colliding with the central portion of the phosphor screen, thereby obtaining a dynamic focus effect. Can be. The fourth electrode 14 forms a quadrupole lens. In the quadrupole lens formed by the fourth electrode 14, the electron beam passing through the fourth electrode 14 exerts a focusing action (convex lens effect) in the vertical direction (vertical direction, Y direction). Has a diverging effect (concave lens effect) in the horizontal direction (lateral direction, X direction). As described above, the quadrupole electric field formed by the fourth electrode 14 has a function of shaping the electron beam colliding with the central portion of the phosphor screen surface to be horizontally long.

As shown in a schematic perspective view in FIG. 1, the electrostatic deflecting plate 16 includes two convergence shield plates 1.
7 and a convergence plate 18 arranged on the left and right outer sides of the convergence shield plate 17. FIG. 1 is a partial view of the electrostatic deflecting plate 16 viewed from the phosphor screen surface side. The ends 18A of the convergence plates 18 on the phosphor screen side protrude more toward the phosphor screen side than the ends 17A of the convergence shield plates 17 on the phosphor screen side. In addition, an end portion 17A of the convergence shield plate 17 on the phosphor screen surface side includes:
A convergence shield parallel plate 19 is disposed at a position vertically sandwiching the three electron beams. Electrostatic deflection plate 16
Can be produced, for example, by cutting, bending, and welding a stainless steel plate.
The electrostatic deflecting plate 16 is attached to a glass bead (not shown).

An anode voltage _VA is applied to the convergence shield plate 17. On the other hand, a voltage of about 95% of the anode voltage _VA is applied to the convergence plate 18. Thereby, as shown in the schematic diagram of FIG. 1B, an electron beam (indicated by a black circle) passing through a space between the convergence shield plate 17 and the convergence plate 18 of the electrostatic deflection plate 16 is shown. Is 2
It is bent in the direction of the electron beam passing through the space between the convergence shield plates 17. On the other hand, FIG.
(C), a quadrupole electric field in the electrostatic deflection plate is formed by the projection 18B of the convergence plate 18 and the parallel plate 19 of the convergence shield. The quadrupole electric field in the electrostatic deflecting plate has a function of shaping the passing electron beam into a vertically long shape. That is, an electron beam (shown by a black circle) passing through a space surrounded by the protruding portion 18B of the convergence plate 18 and the convergence shield parallel plate 19 is vertically elongated. 1B and FIG. 1C correspond to FIG.
5 is a schematic diagram when the electrostatic deflection plate 16 shown in FIG. 5 is cut along a line BB and a line CC.

When the electron beam collides with the central portion of the phosphor screen, the electron beam becomes horizontally long due to the quadrupole electric field formed by the fourth electrode 14. On the other hand, the electron beam passing through the space surrounded by the projecting portion 18B of the convergence plate 18 and the parallel plate 19 of the convergence shield is vertically elongated. As a result, the quadrupole lens effect by the fourth electrode 14 and the quadrupole lens effect by the electrostatic deflecting plate 16 are cancelled, and the spot shape of the electron beam colliding with the central portion of the phosphor screen surface approaches a perfect circle. . When the electron beam collides with the center of the phosphor screen, the deflection yoke does not operate.

When the electron beam collides with the left and right peripheral portions of the phosphor screen surface, no quadrupole electric field is formed by the fourth electrode 14. On the other hand, the electron beam passing through the space surrounded by the projecting portion 18B of the convergence plate 18 and the parallel plate 19 of the convergence shield is vertically elongated. Since the deflection yoke is operating, the electron beam passing through the deflection yoke becomes horizontally long. From the above results, the quadrupole lens effect by the electrostatic deflecting plate 16 and the quadrupole lens effect by the deflection yoke are canceled,
The spot shape of the electron beam colliding with the right and left peripheral portions of the phosphor screen surface approaches a perfect circle as schematically shown in FIG.

The present invention has been described based on the embodiments of the present invention, but the present invention is not limited to these embodiments. The structure of the electron gun for the in-line three-beam type cathode ray tube and the structure of the electrostatic deflecting plate described in the embodiment of the invention are merely examples, and the design can be changed as appropriate. In the embodiment of the invention, the convergence shield plate and the convergence shield parallel plate are formed separately from the phosphor screen surface side end of the convergence shield plate, but the convergence shield plate and the convergence shield parallel plate are separately manufactured. The shield parallel plate may be attached to the convergence shield plate by welding or the like, or the convergence shield parallel plate and the convergence shield plate may be electrically connected by wiring or the like. Alternatively, the convergence shield parallel plate and the convergence shield plate may be assembled in a state where they are not electrically connected to each other, so that an appropriate voltage can be applied to the convergence shield parallel plate.In this case, the convergence shield parallel plate and the convergence shield The same voltage may be applied to the plate and a different voltage may be applied. The type of the in-line three-beam type electron gun for a cathode ray tube is not limited to the high unipotential focus type, but may be, for example, a bipotential focus lens type, a unipotential focus lens type, a high bipotential focus lens type, a tripotential focus lens type, Potential focus lens type, uni-bipotential focus lens type, and other compound lens type electron guns for color cathode ray tubes can be mentioned.

[0027]

In the electron gun for an in-line three-beam type cathode ray tube according to the present invention, a quadrupole electric field can be formed on the electrostatic deflecting plate. Since the distance can be shortened,
The spot shape of the electron beam colliding with the peripheral portion of the phosphor screen surface can be made closer to a perfect circle. Further, by incorporating a quadrupole electrode for forming a quadrupole electric field in the main focus lens system, the spot shape of the electron beam colliding with the central portion of the phosphor screen surface can be made closer to a perfect circle.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an electrostatic deflecting plate in an in-line three-beam type cathode ray tube electron gun of the present invention, and a schematic diagram showing an action of an electron beam passing through the electrostatic deflecting plate.

It is a schematic diagram of a dynamic focus voltage V _DF in-line three-beam method electron gun for a cathode ray tube of the present invention; FIG.

FIG. 3 is a view showing an optical model in a case where an electron beam collides with a peripheral portion of a phosphor screen surface in the in-line three-beam type cathode ray tube electron gun of the present invention.

FIG. 4 is a conceptual diagram of a high unipotential focus type electron gun for a color cathode ray tube.

FIG. 5 is a schematic perspective view and a plan view of a fourth electrode.

FIG. 6 is a schematic perspective view of a conventional electrostatic deflecting plate and a schematic view showing an action of an electron beam passing through the electrostatic deflecting plate.

FIG. 7 is a schematic diagram of a conventional dynamic focus voltage _VDF .

FIG. 8 is a schematic view showing a conventional quadrupole lens effect applied to an electron beam passing through a fourth electrode.

FIG. 9 is a view showing an optical model in a case where an electron beam collides with a peripheral portion of a phosphor screen surface in a conventional electron gun for a cathode ray tube.

FIG. 10 is a diagram schematically showing a spot shape of an electron beam when the electron beam in the electron gun for a cathode ray tube of the present invention collides with a center portion and a corner portion of a phosphor screen surface.

FIG. 11 is a diagram schematically showing a spot shape of an electron beam in a conventional electron gun for a cathode ray tube when the electron beam collides with a central portion and a corner portion of a phosphor screen surface.

FIG. 12 is a schematic view of a conventional color cathode ray tube.

FIG. 13 is a schematic diagram showing a state in which an electron beam colliding around the phosphor screen surface is in an overfocus state.

FIG. 14 is a schematic diagram showing an action of an electron beam deflected toward a peripheral portion of a phosphor screen surface to be received by a deflection yoke.

[Explanation of symbols]

Reference numeral 10: cathode, 11: first electrode, 12 ...
2nd electrode, 12A ... middle electrode, 13 ... 3rd electrode, 14 ... 4th electrode, 14A ... _{4th_1} electrode, 1
4B: _{4th_2} electrode, 14C: _{4th_3} electrode, 15
... Fifth electrode, 16 ... Electrostatic deflection plate, 17 ... Convergence shield plate, 17A ... End of the convergence shield plate on the side of the phosphor screen, 18.
..Convergence plate, 18A... End of convergence plate on phosphor screen side, 18
B: Projecting portion of convergence plate, 19
..Convergence shield parallel plates

Claims (5)

[Claims] (A) a cathode; (b) a pre-focus lens system; (c) a main focus lens system; (d) two convergence shield plates; and left and right outer sides of the convergence shield plates. An electron gun for an in-line three-beam cathode ray tube, comprising: an electrostatic deflection plate comprising a convergence plate; and an end of each convergence plate on the phosphor screen surface side, the end of the convergence shield plate on the phosphor screen surface side. The convergence shield parallel plate protrudes toward the phosphor screen surface side from the end, and the convergence shield plate is disposed at the end of the convergence shield plate on the phosphor screen surface side at a position sandwiching the three electron beams vertically. An electron gun for an in-line three-beam type cathode ray tube, characterized by the following. 2. The electron gun for an in-line three-beam type cathode ray tube according to claim 1, wherein a quadrupole electric field is formed by the projecting portion of the convergence plate and the parallel plate of the convergence shield. 3. The in-line 3 according to claim 2, wherein the electron beam is shaped vertically by a quadrupole electric field.
Electron gun for beam type cathode ray tube. 4. The electron gun for an in-line three-beam cathode ray tube according to claim 1, wherein a quadrupole electrode for forming a quadrupole electric field is incorporated in the main focus lens system. 5. The electron gun for an in-line three-beam cathode ray tube according to claim 4, wherein the electron beam colliding with the central portion of the phosphor screen surface by the quadrupole electric field is shaped horizontally.