KR100418026B1 - Shadow mask for color cathode ray tube - Google Patents

Abstract

PURPOSE: A shadow mask is provided to achieve improved performance of color reproduction by enlarging the color purity margins at corners of a screen. CONSTITUTION: A color cathode ray tube comprises a panel having an inner surface on which a phosphor screen is formed; a shadow mask(100) coupled to the inner surface of the panel; a frame for supporting the shadow mask in such a manner that the shadow mask is spaced apart from the panel; a funnel coupled to the rear end of the panel, and which maintains a vacuum state; a reinforcing band covering the outer surface of the panel; and an electron gun encapsulated in the neck portion of the funnel, and which emits red, green, and blue electron beams. The shadow mask has electron beam passing holes(101,102) formed on the effective surface, wherein the electron beam passing holes have dot shapes and slot shapes.

Description

Shadow mask for color cathode ray tube

The present invention relates to a color cathode ray tube, and more particularly, to a shadow mask in which a plurality of electron beam through holes are formed to perform color selection of an electron beam during operation of the cathode ray tube.

In general, the color cathode ray tube includes a panel 1 mounted on the front surface of the cathode ray tube, a shadow mask 3 having a color discrimination function of an electron beam incident from the inside of the panel 1, and A frame 4 holding the shadow mask 3 fixed thereto, a funnel 2 coupled to the rear surface of the panel 1 to maintain the interior in a vacuum state, and retracted to the rear of the funnel 2; A tubular neck portion 10, an electron gun 6 mounted inside the neck portion 10 to emit an electron beam 11, and a frame to block an external magnetic field applied to the emitted electron beam 11; An inner shield (5) assembled in (4), a deflection yoke (7) surrounding the outer side of the funnel (2) and deflecting the electron beam, a reinforcing band (8) surrounding the side of the panel (1), It is composed of a lug (9) welded to the reinforcing band (8) for coupling and fixing the cathode ray tube to the cabinet.

In the conventional cathode ray tube constructed as described above, the electron beam 11 from the electron gun 6 passes through a hole formed in the shadow mask 3, and then reproduces an image by emitting a phosphor formed on the inner surface of the panel 1 corresponding to the hole. It is supposed to.

In the prior art, in particular, in the cathode ray tube for data processing, it is common that the shadow mask 3 in the inside thereof has a dot structure having an electron beam through hole 13 in the effective surface 12 as shown in FIG. .

Therefore, the electron beam 11 is accelerated by the anode voltage in the through hole 13 of the dot structure to strike the phosphor coated on the inner surface of the panel 1.

However, since most of the cathode ray tubes for data processing have a dot shape of the electron beam through hole of the shadow mask, in particular, there is a problem that pure color reproduction and luminance are considerably inferior to the center of the screen due to less color purity margin at the corner of the screen.

That is, the theoretical color purity margin in the phosphor arrangement shown in FIG. 3 is a phosphor, an electron beam diameter A when the electron beam is present, a phosphor diameter B, a graphite band gap between the phosphor and the phosphor, and a horizontal pitch of the phosphor Ph. In this case, the following expression is possible.

Purity margin = {[(Ph-3B) / 3- (A-B) / 2] / 2 / Mb} * 2

* Mb is the electron beam travel distance when the deflection yoke is moved back and forth.

However, in the shadow mask type structure as described above, mislanding occurs easily when the color purity margin is moved to the X and Y axes, so it is difficult to secure the color purity margin. In a cathode ray tube, the securing thereof becomes more difficult.

On the other hand, the shadow mask of the dot structure as described above has a phenomenon that the luminance is relatively decreased because the electron beam transmittance is smaller than the slot structure as shown in FIG. 4, in order to improve the light emission capacity by increasing the phosphor dot size to improve the margin of the color purity The vicious cycle of diminishing degrees was repeated.

Here, the electron beam transmittance of the dot structure is calculated as follows.

Transmittance (T) = (πr ² / Ph * Pv) * 100 (%)

Where r is the radius of the shadow mask electron beam through hole

The present invention is invented to solve the problems of the prior art as described above by forming the shape of the electron beam through hole of the shadow mask mixed with the dot and slot type, to prevent the decrease in luminance due to lack of color purity margin and decrease in electron beam transmittance The purpose is to help.

1 is a block diagram of a general color cathode ray tube.

Figure 2 is a plan view of a conventional dot type shadow mask.

3 is a diagram showing color purity margins of a dot-type shadow mask;

4 is a view showing the transmittance of a dot-type shadow mask.

Figure 5 is a plan view of the shadow mask of the present invention.

6 is a view showing the color purity margin of the shadow mask of the present invention.

7 is a view showing the transmittance of the present invention shadow mas.

<Explanation of symbols for the main parts of the drawings>

100: shadow mask 101: dot type through hole

102: slot type through hole

The present invention is described in detail below with reference to FIGS. 5 to 7.

First, the configuration of the shadow mask according to the present invention, a dot-type electron beam through hole 101 is formed in the center portion of the shadow mask 100, and a portion of the shadow mask which selects the color of the corner of the screen where color purity margin is weak is shown in FIG. As shown, the slot type electron beam through hole 102 was formed.

The shadow mask of the present invention, which is configured as described above, determines the blow position of the electron beam since the mislanding on the X axis is related to the color purity margin, regardless of the mislanding of the electron beam on the Y axis, especially in a high-definition color cathode ray tube. The correction lens design becomes easier and the color purity margin is easier than before.

In addition, the same shadow mask pitch (Ph, Pv) can be designed to bring the electron beam transmittance larger than the dot shape, so that it is possible to improve the phosphor luminous efficiency to improve the brightness in particularly weak surface corners.

In the present invention, as shown in FIG. 6, the theoretical calculation of the color purity margin is as follows.

Purity margin = {[(Ph-3B) / 3- (A-B) / 2] / 2 / Mb} * 2

The difference from the prior art is that the amount of mislanding of the electron beam on the Y axis does not affect the color purity margin. In other words, even if mis-landing occurs on the Y axis, the same phosphor is also on the Y axis, and thus does not hit a color.

The electron beam passing holes of the slot-shaped shadow mask are more ideal when the electron beam passing holes of the shadow mask are arranged so that the electron beams are positioned at the screen corners which are most deflected.

In addition, the brightness of the shadow mask can be designed to be relatively higher than the dot shape, so that the brightness at the corner of the screen can be improved, while the brightness increase at the corner of the screen almost equals the brightness ratio with the center of the screen. The castle can be secured.

Wherein the electron beam transmittance of the shadow mask slot of the present invention shown in FIG.

It can be expressed as transmittance T = (C * D / Ph * Pv) * 100 (%).

As described above, the shadow mask of the present invention is a cathode ray tube for high-definition color data processing, which greatly secures the color purity margin of the screen corner portion to secure pure color reproduction performance and at the same time reduce the amount of mislanding to improve screen brightness. It works.

Claims (3)

A panel having a fluorescent surface coated on the inner surface, a shadow mask coupled to the inside of the panel, a frame supporting the shadow mask to maintain a predetermined distance from the panel, and a rear end of the panel to maintain an internal vacuum state. In a color cathode ray tube consisting of a funnel, a reinforcing band surrounding the outer surface of the panel, and an electron gun encapsulated in the neck portion of the funnel to emit R, G, B electron beam, the shadow mask is effective surface A shadow mask for color cathode ray tubes, characterized in that the electron beam passing hole inside is mixed in the form of a dot and a slot. The shadow mask for color cathode ray tubes according to claim 1, wherein a slot shape of the electron beam through hole shape is positioned at a corner of a shadow mask effective surface. 2. The shadow mask for color cathode ray tube according to claim 1, wherein the slot shape of the electron beam through hole shape is formed from the center of the mask to the end of the effective surface from 2/3 points along the long side.

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