KR940005493B1 - Shadow mask type c-crt - Google Patents

Abstract

A shadow mask-type color cathode ray tube in which the distance between a phosphor layer and shadow mask is set so that R, G and B electron beams emitted from the respective electron guns pass through a hole of the shadow mask, the fringe R and B electron beams crosses the central G electron beam and recrosses the R and G electron beams passing through nearby holes, thereby obtaining a slow variation of current density at the boundary of the shadow mask.

Description

Shadow Mask Type Cathode Ray Tube

1 is a schematic diagram illustrating an optical path of R, G, and B beams passing through an aperture of a shadow mask in a color cathode ray tube according to the present invention.

2 is a schematic diagram illustrating an optical path of R, G, and B beams passing through an aperture of a shadow mask in a conventional color cathode ray tube.

＊ Explanation of symbols on main parts of drawing

1: face panel 2: fluorescent film

3 _B, 3 _G, 3 _R : electron beam 4: shadow mask

5: Aperture Q, Q _X : Spacing between fluorescent film and face panel

The present invention relates to a color cathode ray tube, and more particularly, to a color cathode ray tube for improving a moiré shape on a screen by increasing a distance between a fluorescent surface of a panel and a shadow mask.

The shadow mask type cathode ray tube is characterized by a structure in which a shadow mask having numerous apertures is arranged at intervals of about 10 mm with respect to the fluorescent film coated with R, G, and B patterns on the screen.

The apertures drilled in the shadow mask are about 200,000 to 400,000 pieces at regular pitches of 0.2 to 0.8 mm.

In the shadow mask, one aperture corresponds to one pair of R, G and B phosphors.

In the electron gun, the radiated R, G, and B electron beams pass through the aperture of the shadow mask and are designed to intersect the R, G, and B electron beams by crossing the R and G electron beams along the axis. .

Since the R, G, and B electron beams emitted from the electron gun are modulated by the received color signal, one set of R, G, and B phosphors emits light to reproduce all colors according to the intensity of each color signal.

In the shadow mask type cathode ray tube configured as described above, the shadow mask is weld-supported on the mask frame supported by the inner side of the face panel to which the fluorescent film is applied by three to four hook springs.

Therefore, in assembling the color cathode ray tube, the shadow mask is suspended inside the face panel while being welded to the mask frame.

In this process, the distance between the shadow mask and the fluorescent film of the face panel (hereinafter referred to as Q value) has a constant value. In other words, the R and B electron beams cross each other in the aperture of the shadow mask by the Q value, and the corresponding phosphor is landing.

In other words, the conventional color cathode ray tube is R, G, B electron beam (3 _R ) with respect to the fluorescent film 2 applied in the order of R, G, B inside the screen 1, as shown in FIG. (3 _G) (3 _B) is passing through the aperture (5) of the shadow mask 4, the R, B electron beam (3 _R) (3 _B), the G electron beam (3 _G) of the center of If the Q values are not kept constant since they cross each other along the axis, each electron beam will collide with another phosphor, resulting in a decrease in color purity.

However, since the cross-section of the phosphor is formed high and low on the screen rather than uniformly, even if the Q value is designed to be constant, the problem of moiré cannot be solved.

An object of the present invention is to provide a shadow mask type cathode ray tube that can improve the moiré shape of the screen by increasing the distance between the shadow mask and the inner surface fluorescent film of the face panel so that color purity does not decrease.

According to the above object, the present invention increases the distance between the shadow mask and the inner surface fluorescent film of the face panel without impairing color purity so that the R, G, and B electron beams emitted from each electron gun pass through any one of the shadow masks. R and B electron beams on both sides intersect the central G electron beam on the axis, and then cross again with the R and B electron beams passing through adjacent apertures immediately before reaching the fluorescent film, and then into the corresponding phosphor of the fluorescent film. By setting the spacing that can be landing, the spacing between the shadow mask and the fluorescent film is substantially doubled, thereby improving moiré.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the exemplary embodiment of the present invention, the same parts as in FIG. 1 are denoted by the same reference numerals to avoid duplication of explanation.

In the shadow mask type cathode ray tube according to the present invention, the distance Q _X between the fluorescent film 2 and the shadow mask 4 applied to the inner surface of the face panel 1 is R, G, B emitted from each electron gun. The electron beam 3 _R (3 _G ) (3 _B ) passes through any of the apertures 5a of the shadow mask 4, so that the R and B electron beams 3 _R (3 _B ) are at the center G. electron beam (3 _G) for a cross-axis, then the R, B electron beam passes through the aperture (5b) (5c) adjacent to the just prior to reaching the phosphor film _{(2) (3 R) (} 3 B) It is set to a distance that can be landed again with the corresponding phosphor of the fluorescent film 2 after re-crossing with.

Q _X is actually represented by Q _X = Q + ΔQ.

Where Q is the interval between the fluorescent film and the shadow mask associated with the conventional color cathode ray tube, and ΔQ is the amount of increase in the interval.

In addition, the screen pitch of a color cathode ray tube is calculated | required by following formula (I).

Where L ψ is the distance from the electron gun to the fluorescent film, P _S is the screen pitch, and P _M is the aperture pitch of the shadow mask.

In the color cathode ray tube according to the present invention

And substituting Ⅱ] in the above formula Ⅰ]

Becomes

In the conventional color cathode ray tube, the change of Q value is

Becomes

In the above formula, S means the distance from the G electron gun to the R electron gun or the B electron gun on both sides.

In the color cathode ray tube according to the present invention,

And substituting Equation III] and IV] into Equation V]

blast furnace

Therefore, when the Q _X value of the color cathode ray tube according to the present invention is twice the Q value set in the conventional color cathode ray tube, it can be seen that the R and B electron beams are crossed twice and landed in the corresponding phosphor.

If the R and G electron beams are crossed twice and landed on the corresponding phosphor, the change in the current density of the shadow portion of the shadow mask can be smoothed. As a result, the sharpness of the boundary portion is reduced, and the moiré is recognized on the screen. In addition, as the Q value increases, the work of assembling the shadow mask inside the panel can be further facilitated.

Claims (1)

The spacing Q _X between the fluorescent film 2 and the shadow mask 4 coated on the inner side of the face panel 1 is R, G, B electron beams ( _3R ) ( _3G ) radiated from each electron gun ( 3 _B) intersects the hit any one of the upper (R, B electron beam (3 _R) to both sides through the 5a) (3 _B) G electron beam is in the center (3 _G) of the shadow mask 4 in the axial and then, the aperture (5b), (5c), the R, passing through the B electron beam (3 _R) (3 _B) and re-crossing the phosphor layer (2) adjacent to jeokjeon to reach the phosphor layer (2) A shadow mask type color cathode ray tube, characterized in that it is set at intervals landing with the phosphor.