JPH09231915A - Cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high resolution not less than 900 TV lines in horizontal resolution even in the large current range by reducing the spherical aberration of an electron lens. SOLUTION: In a neck 2 of a bulb 1, a negative electrode 3, a control electrode 4, an accelerating electrode 5, a cylindrical first positive electrode 7, a cylindrical focusing electrode 8 and a cylindrical second positive electrode 10 are arranged one by one in an electron beam direction 11. If D0 denotes a bore of a cylindrical part on the side of the first positive electrode 7 to the focusing electrode 8, and D1 denotes a bore of a cylindrical part on the side of the focusing electrode 8 to the first positive electrode 7, and D2 denotes a bore of a cylindrical part on the side of the focusing electrode 8 to the second positive electrode 10, and D3 denotes a bore of a cylindrical part of the second positive electrode 10, the inequalities D0 <D1 and D2 <D3 are satisfied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube having a unipotential type electron gun used for a television receiver, a display and the like.

[0002]

2. Description of the Related Art In a cathode ray tube having a unipotential type electron gun, in order to reduce the spherical aberration of the electron beam focusing lens to reduce the spot diameter on the fluorescent screen, the electron lens in the preceding stage constituting the focusing lens is Japanese Patent Publication No. 3-79813 describes a technique for making the lens aperture smaller than the lens aperture of the electronic lens in the subsequent stage.

This encloses a cathode, a control electrode, an acceleration electrode, a tubular first anode, a focusing electrode having two tubular portions, and two tubular portions of a focusing electrode in the neck of a cathode ray tube bulb. Cylindrical second anodes are arranged in sequence, the diameter d ₁ of the cylindrical portion of the focusing electrode on the first anode side, the diameter d ₂ of the cylindrical portion of the focusing electrode on the second anode side, the cylindrical portion of the second anode. When the caliber of d is ₃ ,
The relationship between the respective diameters is d ₁ <d ₂ <d ₃ .

[0004]

However, when such a conventional cathode ray tube is used as a projection type tube which is used in a large current region of 700 μA to 1 mA because a particularly high light output is required, a high-definition television is required. There is a problem that the horizontal resolution of 900 TV lines required for broadcasting cannot be obtained.

The present invention provides a cathode ray tube capable of reducing the spherical aberration of an electron lens and obtaining a high resolution of 900 TV lines or more in horizontal resolution even in a large current region.

[0006]

A cathode ray tube of the present invention includes a cathode, a control electrode, an acceleration electrode, a cylindrical first anode, a cylindrical focusing electrode and a cylindrical second anode in a neck of a bulb. Sequentially arranged in the electron beam direction, the diameter of the focusing electrode side tubular portion of the first anode is D ₀ , the diameter of the first anode side tubular portion of the focusing electrode is D ₁ , and the focusing electrode is Where D ₂ is the diameter of the second anode-side tubular portion and D ₃ is the diameter of the second anode tubular portion, D ₀ <D ₁ and D ₂ <D ₃
It satisfies the following relationship.

In the cathode ray tube of the present invention, the aperture of the electron lens A formed between the first anode and the focusing electrode becomes large as shown by the solid line in FIG. Angle θ of an electron beam incident on a large-diameter electron lens B formed between the focusing electrode and the second anode
₂ and the emission angle θ ₃ emitted from the electronic lens B to the image point
And the beam spot diameter at the image point can be reduced.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings.

The cathode ray tube according to the first embodiment of the present invention used for a projection type tube has a unipotential electron gun 13 in a neck 2 of a bulb 1, as shown in FIGS. A fluorescent surface 15 is provided on the face 14 facing the surface 13.

The unipotential electron gun 13 has a cathode 3,
A control electrode 4 having a bottomed cylindrical shape containing the cathode 3 therein, an acceleration electrode 5 also having a bottomed cylindrical shape, and an electron beam passage hole 6 on the side of the acceleration electrode 5 formed with a bottomed cylindrical shape. First done
The anode 7, the focusing electrode 8 which is arranged apart from the first anode 7 and which is formed in a tubular shape, and the second electrode which is formed in a tubular shape so as to surround a part 9 of the tubular portion of the focusing electrode 8. The anodes 10 are sequentially arranged in the emission direction of the electron beam 11.

The electrodes 4, 5, 7, 8 and 10 are each made of FeNiCo, stainless steel or the like, and are provided on both sides of each outer peripheral surface in order to accurately fix the electrodes in a separated state. On the bead glass 12,
It is held and fixed by embedding a fixing bracket.

Regarding the tubular portion of the focusing electrode 8, both end portions are formed with tubular portions having different diameters, and the leakage current between the neck 2 and the focusing electrode 8 is prevented and the first portion is provided.
In order to increase the diameter of the electron lens A between the anode 7 and the focusing electrode 8, a groove 16 is provided on the inner surface of the bead glass 12 facing the cylindrical portion of the focusing electrode 8 on the first anode 7 side, The diameter D ₁ of the cylindrical portion on the first anode 7 side is increased. Regarding the relationship between the diameters of the electrodes 7, 8 and 10, the diameter of the tubular portion of the first anode 7 on the focusing electrode side 8 is D ₀ , and the diameter of the tubular portion of the focusing electrode 8 on the first anode 7 side is D ₁ , the second anode 10
When the diameter of the cylindrical portion of the focusing electrode 8 on the side is D ₂ and the diameter of the cylindrical portion of the second anode 10 that surrounds the diameter D ₂ of the cylindrical portion of the focusing electrode 8 is D ₃ , D ₀ <D ₁ and D ₂ <D ₃ . Then, this cathode ray tube includes a first anode 7 and a second anode 7.
An anode voltage Va is applied to the anode 10 and a focus voltage Vfoc lower than the anode voltage Va is applied to the focusing electrode 8 to cause the electron beam 11 to strike the fluorescent screen 15 to form an image.

Next, the operation of the cathode ray tube will be described. In general, the beam spot diameter ds of the unipotential electron gun is the diameter do at the crossover point, the incident angle θ ₁ of the electron beam incident on the electron lens A, the potential Vo at the crossover point, and the electron lens B is emitted to the image point. Exit angle θ ₃ ,
When the potential of the image point (second anode voltage) Va is set, Lagrange-
From the Helmholtz equation, ds = do ・ θ ₁・ √Vo / (θ ₃・ √V
It can be represented by a).

However, as shown by the broken line in FIG. 3, when the electron lens A cannot be made sufficiently large like the conventional unipotential electron gun of the cathode ray tube, the electron lens A has spherical aberration, so that the electron The incident angle θ ₄ and the exit angle θ _{5 of} the electron beam incident on the electron lens B from the lens A become small, and as a result, the characteristic that the spherical aberration of the electron lens B having a large diameter is small cannot be fully utilized.

On the other hand, in the cathode ray tube according to the first embodiment of the present invention, as shown in FIG. 1, the groove 16 is formed on the inner surface of the bead glass 12 facing the cylindrical portion of the focusing electrode 8 on the first anode 7 side. To increase the diameter D ₁ of the cylindrical portion of the focusing electrode 8;
Since the diameter relationships of the electrodes 7, 8 and 10 are D ₀ <D ₁ and D ₂ <D ₃ , respectively, as shown by the solid line in FIG. The aperture of the electron lens A formed between them becomes large, and the incident angle θ ₂ of the electron beam incident from the electron lens A to the large aperture electron lens B formed between the focusing electrode 8 and the second anode 10 is And the emission angle θ ₃ emitted from the electron lens B to the image point becomes large.

That is, by increasing the electron lens diameter of the electron lens A, the electron lens B having a small spherical aberration is obtained.
Since it is possible to make full use of the characteristics of, the beam spot diameter of the image point can be reduced.

Therefore, according to the cathode ray tube of the first embodiment of the present invention, the horizontal resolution of 900 is achieved even when used in a large current region.
You can get TV books.

(Embodiment 2) FIG. 4 shows Embodiment 2 of the present invention. This Embodiment 2 is different from the above Embodiment 1 in that a part of the cylindrical portion of the first anode 7 is The difference is that the focusing electrode 8 is surrounded by a tubular portion.

According to the second embodiment, a part of the tubular portion of the first anode 7 is surrounded by the tubular portion of the focusing electrode 8, so that the first anode 7 and the neck 2 or the first anode 7 are formed. Discharge between the anode 7 and the bead glass 12 can be prevented, and the quality against high pressure can be stabilized.

In the first and second embodiments of the present invention, the diameter of each of the electrodes 7, 8 and 10 is D ₀ <.
In order to establish a relationship of D ₁ and D ₂ <D ₃ , the focusing electrode 8
Has been described as having a shape in which cylindrical portions having different diameters are provided at both ends thereof. Regarding the shape, D ₁ <D ₂ or D
Tapered cylinder with a diameter relationship of ₁ > D ₂ or D ₁
A straight cylindrical shape having a diameter relationship of = D ₂ may be used. Further, by forming the focusing electrode 8 into a tapered tubular shape or a straight tubular shape, the focusing electrode 8 can be easily configured, and the processing accuracy of the tubular portion of the focusing electrode 8 is improved.
The shape accuracy of the electron lens A and the electron lens B can be improved.

Further, the focusing electrode 8 and the second anode 10 of the first and second embodiments of the present invention and the first anode 7 and the focusing electrode 8 of the second embodiment are partially overlapped with each other. However, the present invention is not limited to this, and if the size relation of the respective apertures is the same as that of the above-described embodiment of the present invention, a desired electron lens can be formed, and thus the effect of the present invention is obtained. be able to.

In the first and second embodiments of the present invention, the case where the cathode ray tube is used as the projection type tube has been described, but the same effect can be obtained even when the cathode ray tube is used in other monochrome or color cathode ray tubes. Obtainable.

[0023]

EXAMPLES Next, examples of the present invention will be described.

(Embodiment 1) A cathode ray tube (product of the present invention) according to a first embodiment of the present invention has a structure shown in FIGS. 1 and 2.
The diameter D ₀ of the first anode 7 is 10 mm, the diameter D _{1 of the} focusing electrode 8 is 13 mm, the diameter D ₂ is 15 mm, and the total length is 4 mm.
8 mm, and the diameter D ₃ of the second anode 10 is 22 mm,
An anode voltage Va of about 32 kV, a focus voltage Vfoc of about 9 kV (a cathode current of 2 mA, a voltage value at which the beam spot was just focused), and a cutoff voltage Vc of about 190 V were used.

[0025] For comparison, the diameter D ₁ of the bore D ₀ and focusing electrode 8 of the first anode 7 shown in FIG. 1 and 10 mm, and otherwise conventional cathode ray tube of the same specifications (conventional ) Also produced.

The relationship between the current amount of the cathode 3 (cathode) and the beam spot diameter of the image point (value at the maximum brightness ratio of the spot profile of 5%) and the response characteristic to the horizontal resolution when the current amount of the cathode 3 is about 1 mA (horizontal resolution) The horizontal resolution is plotted on the axis and the ratio M of the output image to the input image is plotted on the vertical axis. For a projection tube, the horizontal resolution is determined at M = 0.15), and the results are shown in FIGS. 5 and 6. The following results were obtained. Curve A shows the product of the present invention and curve B shows the conventional product.

As is apparent from FIG. 5, the product of the present invention is
In the entire current range of 0.2 to 8 mA, the beam spot diameter is significantly improved as compared with the conventional product, and as is clear from FIG. 6, the product of the present invention has a horizontal resolution of about 800 T.
It can be seen that the resolution of about 950 TV lines, which is sufficiently compatible with high-definition broadcasting, has been obtained compared to the conventional V lines.

[0028]

As described above, according to the present invention, a horizontal resolution of about 950 TV lines can be obtained even when used in a large current region, and a cathode ray tube sufficiently compatible with high-definition broadcasting can be obtained. .

[Brief description of drawings]

FIG. 1 is a sectional front view of a main part of a cathode ray tube according to a first embodiment of the present invention.

FIG. 2 is a sectional front view of the cathode ray tube.

FIG. 3 is an operation explanatory diagram of the cathode ray tube according to the first embodiment of the present invention and the conventional cathode ray tube.

FIG. 4 is a sectional front view of a main part of a cathode ray tube according to a second embodiment of the present invention.

FIG. 5 is a diagram showing the relationship between the amount of current and the beam spot diameter of the cathode ray tube of the present invention product and the conventional product.

FIG. 6 is a horizontal resolution characteristic diagram of the cathode ray tube of the present invention product and the conventional product.

[Explanation of symbols]

 1 Valve 2 Neck 3 Cathode 4 Control Electrode 5 Accelerating Electrode 7 First Anode 8 Focusing Electrode 10 Second Anode 11 Electron Beam

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masayuki Omori 1-1 1-1 Sachimachi Takatsuki-shi, Osaka Prefecture Matsushita Electronics Industrial Co., Ltd. (72) Mitsuhiro Otani 1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. Within

Claims (1)

[Claims] 1. A cathode, control electrode,
Accelerating electrode, tubular first anode, tubular focusing electrode and tubular
Second anodes are sequentially arranged in the electron beam direction, and
The diameter of the cylindrical portion of the pole on the side of the focusing electrode is D₀And then focus
The diameter of the first anode side tubular portion of the electrode is D₁And before
The diameter of the second anode side tubular portion of the focusing electrode is D_Twoage,
The diameter of the cylindrical portion of the second anode is D_ThreeAnd D₀<D
₁, And D _Two<D_ThreeCharacterized by satisfying the relationship
Cathode ray tube.