JPS5840756A - Mask-focusing color cathode-ray tube - Google Patents

Abstract

PURPOSE:To correct the electric field which is formed around part of a shadow mask which corresponds to the periphery of a picture surface, and realize the homogenization of part of an electron lens corresponding to the effective part of the mask by providing the peripheral part of the shadow mask with a line of plural penetrating holes which have the same regularity as the electron-beam passing holes of the effective part. CONSTITUTION:A magnified figure of the vicinity of a shadow mask is illustrated in the figure. The symbol 18 represents a screen, and the symbol 19 represents a terminal beam-passing hole of the effective part of the mask. The symbol 20 represents a penetrating hole provided in the peripheral part of the mask, which is arranged so that it has the same regularity as the terminal beam passing hole 19. The symbol 21 represents an equiphase line. Here, the above effective part means a part which includes penetrating holes corresponding to phosphors forming a screen and in which passing electron beams can make the phosphors to emit light. The penetrating holes 20 of the peripheral part of the mask don't contribute to the emission of the phosphors. By providing the penetrating holes 20 which have the same regularity as the penetrating holes of the above effective part in the peripheral part of the mask, the conventional distortin of an electron lens formed at the end part of the effective part is corrected, and can be made equal to the distortion of the lens formed at the center of the effective part.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mask focusing type color cathode ray tube, and more particularly to electric field correction near the shadow mask corresponding to the edge of the screen.

Generally, color cathode ray tubes have a shadow mask with a color selection mechanism, and therefore have a problem of poor electron beam utilization.

A method to solve the above problem is to use a mask-focused color pole ray tube. FIG. 1 is a schematic diagram showing an example of a mask focusing plate color cathode ray tube, which includes an electron gun (1) that generates three beams, a shadow mask (2), and a screen (3) consisting of three color phosphors. ), and different potentials are applied to the shadow mask and screen. Generally, the shadow mask potential is set lower than the screen potential.

Figure 182 is an enlarged view of the vicinity of the rear disk in Figure gJ&1. (2) and (3) are shadow masks and screens, and the screen y on the inner surface of the panel (4 '), the shadow mask potential is set to the screen potential **<, so an electron lens is formed near the electron beam passage hole (5) as shown by the r-)i force potential line (6). .Electronic beam A (711), (7G) - (7B) passing through the electronic beam five passing holes is *
The ia electrons are focused onto the corresponding phosphor.

Figure v4S is an enlarged view of the vicinity of a general color Ik polar ray tube O shadow mask corresponding to Figure 2. Shadow mask (phantom is O, single ζ, which has the same potential as the screen; it has a color selection mechanism and is manufactured by Rudasha).

As is clear from Figures 1 to 3, the mask-based color cathode-tube Q system uses technology to form an electron lens in the mask section and focus the passing beam onto the screen. By making the beam passage hole much larger than that of conventional color shaded ray tubes, the beam utilization rate is increased.

Here, a problem specific to mask focusing and cathode tube L is the uniformity in the effective part of the mask, especially the uniformity at the end of the effective part, of the electron lens used for electron beam perforation. The structure shown in FIG. WI1 will be explained below as an example.

! Figure J4 and Figure WIs are enlarged views of the central part and the vicinity of the end of the effective part of the mask in Figure 1.

(8) and 0 are the screens, and (9) and I are shadow masks. Equipotential lines obtained by applying different potentials to the screen and shadow mask are shown in CLI and a. As is clear from FIGS. 4 and 5, the lens shape at the center of the mask is formed symmetrically with respect to the center line Qa of the electron beam passage aperture aυ, whereas the electron beam passage at the effective tidal part The lens shape is distorted at the hole. This is distortion due to the influence of the potential of the peripheral edge aη. Naturally, the beam focusing effect is also disturbed, resulting in a deterioration of image quality.

The present invention provides means for solving the above problems. The explanation will be given below based on Figure %6.

The WIG diagram is an enlarged view of the vicinity of the shadow mask in one embodiment of the present invention. The α barrel is the screen, the ridge is the beam passing hole at the end of the active part of the mask, and (4) is the through hole provided at the periphery, which are arranged with the same regularity as the mouse. o indicates equipotential lines.

Here, the effective part refers to a part in which the through holes correspond to the phosphors forming the screen, and the electron beams passing therethrough cause the phosphors to emit light. The peripheral O through-hole does not contribute to the light emission of the phosphor at all. By providing a hole in the periphery with the same regularity as the hole in the effective part as shown in Fig. 6, the distortion of the conventional electronic lens at the end of the effective part can be corrected, and the lens at the center of the effective part can be corrected. Same hometown 1 = can. In this case, the arrangement and number of the peripheral edge holes may be determined by the potential difference between the screen and the shadow mask. The effect of preventing deterioration of image quality due to mechanical distortion can also be obtained.

In the above explanation, the case of a mask-focusing color cathode-ray tube with a single mask was used as an example, but even in a mask-focusing color cathode-ray tube with multiple masks, at least one shadow mask has fluorescent light. A similar effect can be obtained by applying the present invention to a mask to which a different potential from that of the body screen is applied.

[Brief explanation of the drawing]

Fig. 131 is a schematic diagram showing an example of a mask focusing plate color cathode ray tube, Fig. 2 is an enlarged schematic diagram showing the vicinity of the shadow mask in Fig. 1, and Fig. 133 is an enlarged schematic diagram showing the vicinity of the shadow mask of a normal color cathode ray tube. 4 and 133 are enlarged schematic diagrams showing the central part and the vicinity of the end of the effective part of the shadow mask shown in FIG. 1, respectively, and FIG. FIG. 3 is an enlarged schematic diagram showing the vicinity of the mask. (1)...electron gun, (2), (9), (
t4... Shadow mask (3) t (s), QL... Screen, (4R), (4G), (4
B)...Fluorescent material, (4s...Black light absorbing material (4')
)... Panel, (5), Ql) - Electron beam passing hole (61, al, (15, (2m) - jl t
ffi ml, (7R), (7G), (7B)・
・・Electron beam, 0・−Center line aη・・Shadow mask periphery, **, Cod・−Electron beam passing hole at the periphery of mask effective area (
1)・-Through hole in the periphery of the mask (7317) Representative Patent Attorney Noriyuki Chika 01! or 1 person) Figure 1

Claims (2)

[Claims] (1) A mask comprising at least an electron gun, a shadow mask having a large number of electron beam passage holes, and a phosphor screen made up of a large number of elements, and a different potential from that of the phosphor screen is applied to the shadow mask. In the focusing disk color cathode ray tube, an electronic beam bundle type color cathode ray tube has an effective part at the periphery of the shadow mask. (2) At least an electron gun, a plurality of shadow masks having a large number of electron beam passing holes, and a phosphor screen consisting of a large number of elements, and at least one of the plurality of shadow masks has the phosphor. In a mask-focused color cathode ray tube, a potential different from that of the phosphor screen is applied to the periphery of the shadow mask, to which a potential different from that of the phosphor screen is applied, with the same or similar rules as the electron beam passage holes in the effective part. 1. A one-sphere focusing color cathode ray tube, characterized in that a plurality of through-hole rows are provided.