JPS62133649A - Electron gun structure for color picture tube - Google Patents

Abstract

PURPOSE:To make the uniformity of resolution and focus ability of an electron gun the same as or higher than the other electron guns even though a current larger than the others flows to the electron gun to excite a phosphor of a lower luminous efficiency, by making the opening diameter of at least the control electrode, of the control electrode and the acceleration electrode of the electron gun responding to the phosphor of the lowest luminous efficiency. CONSTITUTION:The opening diameter D1 of the control electrode 1R of the central electron gun 10R which excites the red phosphor of the worst luminous efficiency is set smaller than the opening diameter D2 of the control electrodes 1G and 1B of the both side electron guns 10G and 10B. Therefore, even though a much larger current is picked up from the central electron gun 10R, in order to obtain a same level brightness as the phosphor excited by the electron guns 10G and 10B of the both side, or a standard white color of 9,300 deg.K, for example, an increase of crossover images can be limited, because the opening diameter D1 of the control electrode 1R is smaller than the opening diameter D2 of the other control electrodes 1G and 1B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electron gun assembly for a color cathode ray tube, and particularly to an electron gun assembly suitable for a display color cathode ray tube used in a high-density display device.

[Conventional technology]

Conventionally, the electron gun assembly of a color cathode ray tube has three primary colors of red, green,
It has a configuration in which unit electron guns 11JIIG and IIB, which correspond to blue phosphors and have the same structure to excite each of these phosphors, are arranged in the same plane with equal distances S maintained, and the same current is generated. [Problem to be solved by the invention] Today, color cathode ray tubes with high resolution custom-made for displaying various news, so-called color display A pole ray tube is used. In order to achieve high-density display, the color cathode ray tube must have high resolution and uniform focus characteristics, the video circuit must have a wide frequency band to increase the horizontal resolution of the display screen, and the vertical resolution of the display screen must be high. In order to increase the number of scan lines, it is necessary to have a large number of scanning lines. However, in order to perform high-density display on a display device, widening the frequency band of the image circuit on the circuit increases the cost of the circuit, so it is necessary to increase the number of scanning lines to increase the resolution without widening the C area. is commonly practiced. To increase the number of scanning lines, the vertical deflection frequency of the current standard TV system is 6.
It is necessary to lower 0Hz, but if it is set too low, the screen will flicker, so in color cathode ray tubes, T is placed on the fluorescent surface.
A so-called long afterglow phosphor, which has a longer afterglow time than the P-22 phosphor for V, is used. Based on these facts, the vertical polarization frequency is set to 40 to 50 Hz, and the fluorescent surface has an afterglow time of 10
Green phosphor of P-39 and P-2 which is 0-120m5ec
No. 7 red phosphor is used. Further, conventionally, there was no front wall light with a long afterglow, but now there is also a P-22 blue phosphor co-activated with gallium. However, all of the above-mentioned long afterglow phosphors have lower luminous efficiency than the P-22 phosphor, and the P-27 red phosphor is the worst. For this reason, when adjusting a color cathode ray tube to obtain a standard white color at, for example, 9300°, the beam current of the electron gun that excites each of the red, green, and blue phosphors is the lowest for green, and the lowest for blue. A large amount of current is required for the red head, and currently 1.4 times as much beam current is required to excite the red phosphor of P-27 as for the green of P-39.

Generally, as the current increases, the resolution and focus uniformity of the electron lens of the electron gun deteriorate. Therefore, in order to obtain the above-mentioned white color using a conventional electron gun assembly having the same resolution characteristics and focus characteristics for the same current, the red electrons corresponding to the red phosphor with the lowest luminous efficiency are used. Gun II
If the current flowing through I( is significantly larger than that of the other electron guns 11G2 and 11B), the resolution S and focus uniformity of the red electron gun 11R deteriorate significantly compared to the other electron guns.

[Means for solving problems]

The electron gun assembly for a color cathode ray tube of the present invention controls the electron gun corresponding to the phosphor having the lowest luminous efficiency among the phosphors that emit light in three colors, and controls at least 1111E of the accelerating electrodes.
By making the aperture diameter of the pole smaller than that of other electron guns, the uniformity of resolution and focus can be maintained even if more current flows through the electron gun that excites the phosphor with low luminous efficiency than the other electron guns. 0 [Embodiment] Next, the present invention will be explained with reference to the drawings.

FIG. 1 shows a schematic cross-sectional view of an in-line type electron gun body 10 of a color cathode ray tube based on a practical example of the present invention. The central electron gun 10R has a pixel made of a P-27 red light emitting phosphor, and the outer electron gun 10G has a pixel made of a P-39 green light emitting phosphor. 10B is P-2
This method excites pixels consisting of a blue-emitting phosphor of 2 or a blue-emitting phosphor with afterglow properties whose main component is ZnS-AgGa, and the pixels are spaced at equal intervals S, which is the same as in the conventional method. They are arranged in the same plane to form an electron gun assembly 10.

The aperture diameter D1 of the control electrode IR of the central electron gun 10R, which excites the red phosphor with the lowest luminous efficiency, is the control electrode IG of the electron gun 10G and IOH on both sides.

It is set smaller than the opening diameter D2 of IB.

Generally, the resolution and focus uniformity of an electron gun are determined by the size of a crossover image determined by the relative dimensions of the shadow, the control electrode, and the accelerating electrode, and especially by the aperture diameter of the control electrode. Therefore, in order to maintain good resolution and focus uniformity, the cross-over image can be made smaller by reducing the aperture diameter of the control electrode.

Therefore, in the above-described electron gun assembly 10, the central electron gun 1
0R is the aperture diameter of the control voltage ff1lR, even if an excessive amount of current is drawn from the electron guns on both sides, in order to obtain the same brightness as the phosphor excited by the electron guns LOG and IOB on both sides, or standard white color at, for example, 9300°. Dz is another control electrode IO,
Since the diameter is smaller than the aperture D2 of IB, it is possible to reduce the increase in crossover image by 2.

2. In the embodiment, the case where only the aperture diameter of the control electrode IR is reduced is described, but Control-8! Polar IR1 accelerating electrode 2
You can make both of them smaller.

Furthermore, although an in-line type electron gun has been described, the electron gun array is not limited to the in-line type, but may be a delta type arranged at the vertices of a triangle.

〔Effect of the invention〕

As explained above, the aperture diameter of at least the control electrode of the electron gun that excites the phosphor pixels with significantly lower luminous efficiency than the phosphor pixels that emit light in two colors in the three-electron gun type color cathode ray tube. By making the aperture diameter smaller than the aperture diameter of the control electrode of other electron guns, the resolution and focus of the electron gun that excites the phosphor pixels, which have significantly lower luminous efficiency than the phosphor pixels that emit light in other two colors, can be improved. It is possible to obtain an electron gun assembly having the same characteristics as other electron guns without deteriorating its properties compared to other electron guns.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an in-line electron gun assembly according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a conventional in-line electron gun assembly. 10G, IOR, IOB, IIR, IIG, IIB・-
...Unit electron gun, IG, IR, lf3...
Acceleration electrode for control electrode, 2G, 2) (,, 2B...).

Claims (1)

[Claims] In an electron gun assembly for a color cathode ray tube that has three electron guns that emit three electron beams that excite red, blue, and green phosphor pixels, the control electrode of the electron gun corresponds to the phosphor pixel with the lowest luminous efficiency. An electron gun assembly for a color cathode ray tube, characterized in that, among the accelerating electrodes, at least the control electrode has an aperture diameter smaller than the aperture diameters of other electron guns.