KR19980059347A - Fluorescent film of double layer for flickerless cathode ray tube and its manufacturing method - Google Patents

Abstract

In order to reduce the problem of flicker in cathode ray tubes, the first layer of the double layer is a phosphor film of a phosphor selected from phosphor groups of InBO ₃ : Tb, Zn ₂ SiO ₄ : Mn, and La ₂ O ₂ S: Tb. And a second layer provide a double layer fluorescent film for a flickerless cathode ray tube consisting of a fluorescent film of a phosphor selected from phosphors of ZnS: Cu, Al or ZnS: Cu, Al, Au and a method of manufacturing the same.

Description

Fluorescent film of double layer for flickerless cathode ray tube and its manufacturing method

[Industrial use]

The present invention relates to a double layer fluorescent film for a flickerless cathode ray tube (CDT) and a method of manufacturing the same, and more particularly, to reduce the flicker phenomenon, which is a problem in the cathode ray tube, Instead of a single layer of ZnS: Cu, Al, (Au), which is used as a phosphor, the panel is made of one phosphor selected from the group of InBO ₃ : Tb, Zn ₂ SiO ₄ : Mn, and La ₂ O ₂ S: Tb with long afterglow characteristics The first layer is applied, and then a phosphor of ZnS: Cu, Al, (Au) is applied thereon to make a double layer, thereby reducing the flicker phenomenon of the cathode ray tube. It relates to a membrane and a method of making the same.

[Prior art]

A typical shadow-mask-type CRT has three electron beams, red, green, and blue, which are irradiated by an electron beam firing device, through a hole in a shadow mask, concentrating at one point, and then inside the panel. Each electron beam collides with red, green, and blue phosphors formed on a phosphor screen to reproduce a predetermined image.

The fluorescent film is composed of red, green, and blue phosphors formed in a predetermined pattern and a black matrix, which is a light absorbing film formed on the same surface between the phosphors. The process for forming the fluorescent film usually consists of the following steps. After applying the photoresist to the panel, the panel is dried by heat or the like, and the panel is exposed by irradiating ultraviolet rays through a mask slot. Thus, the exposed panel is cleaned and developed to remove the unexposed photoresist and dry. As described above, the black matrix is manufactured by applying a black matrix material on the panel in which the photoresist film is formed and the non-formed portion are regularly arranged, followed by etching. Thus, the fluorescent film is manufactured by forming a fluorescent film using the red, green, and blue fluorescent substance intensively in the site where the black matrix dot of the panel in which the black matrix was formed does not exist.

As the green phosphor, a (Zn, Cd) S: Cu, Al phosphor was conventionally used, but a ZnS: Cu, Al phosphor containing no Cd due to Cd pollution problems was used. However, since ZnS: Cu, Al phosphors are smaller in chromaticity x value compared to x values of (Zn, Cd) S: Cu, Al phosphors, when the standard white is D65, there is a drawback that a large proportion of current flows in the enemy electron gun. In addition, the white luminance is also reduced by 10%. Because of this problem, ZnS: Cu, Au, Al phosphors containing no Cd near the color tone of (Zn, Cd) S: Cu, Al phosphors are used. Table 1 shows several characteristics of the green phosphor.

Characteristics of each phosphor Relative luminance (%) Color coordinates (x / y) Afterglow time ZnS: Au, Al, Cu 100 0.300 / 0.605 140㎲ ZnS: Al, Cu 105 0.275 / 0.604 140㎲ InBO ₃ : Tb 55 0.334 / 0.590 15 ms La ₂ O ₂ S: Tb 60 0.323 / 0.596 1.5 ms Zn ₂ SiO ₄ : Mn 55 0.204 / 0.702 150 ms

Luminance and color coordinates are measured with a PTE device (dimountable).

Afterglow characteristics measured 1/10 afterglow time using an oscilloscope.

ZnS: Cu, Al, (Au) green phosphors, which are currently used in cathode ray tubes, cause severe flicker due to the afterglow time (1/10 decomposition time) of about 140㎲. This problem of flicker can be solved somewhat by increasing the horizontal frequency. However, the doming of the mask due to the frequency increase is severe, resulting in a problem in which the landing is not correct.

The present invention has been made to solve the problems of the prior art as described above, an object of the present invention is to reduce the flicker phenomenon of the cathode ray tube, and to improve the brightness of the double layer fluorescent film of the cathode ray tube and its manufacture To provide a way.

1 is a cross-sectional view of a fluorescent film formed in a conventional cathode ray tube panel,

2 is a cross-sectional view of a fluorescent film formed of a double charge of a green phosphor as an embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

1 panel 2 BM film (black matrix film)

3: green fluorescent film (ZnS: Cu, Au, Al)

4: blue fluorescent film 5: red fluorescent film

6: green fluorescent film: first layer coating (InBO ₃ : Tb, Zn ₂ SiO ₄ : Mn, La ₂ O ₂ S: Tb group phosphor selected from)

7: green fluorescent film: second layer coating (one phosphor selected from ZnS: Cu, Al and ZnS: Cu, Al, Au group)

The present invention has the following configuration to achieve the above object of the present invention.

In the present invention, when the green phosphor having the characteristics shown in Table 1 is applied to the panel, the first layer of the double layer is phosphor selected from phosphor groups of InBO ₃ : Tb, Zn ₂ SiO ₄ : Mn, and La ₂ O ₂ S: Tb. And a second layer provide a double layer fluorescent film for a flickerless cathode ray tube consisting of a fluorescent film of a phosphor of ZnS: Cu, Al or ZnS: Cu, Al, Au.

The first layer of the black matrix formed cathode ray tube panel is formed by forming one phosphor selected from the group InBO ₃ : Tb, Zn ₂ SiO ₄ : Mn, and La ₂ O ₂ S: Tb, and the second layer above the phosphor. The present invention provides a method for producing a double layer fluorescent film for a flickerless cathode ray tube comprising the step of forming a fluorescent film of a ZnS: Cu, Al or ZnS: Cu, Al, Au phosphor.

In addition, the amount of the phosphor used in the second layer is preferably a fluorescent film of a double layer for a flickerless cathode ray tube having a thickness of 2 to 15 µm.

The following describes preferred embodiments to aid the understanding of the present invention. However, the following examples are merely provided to more easily understand the present invention, and the present invention is not limited to the following examples.

EXAMPLE

Determination of the optimum coating amount of the phosphor used in the first layer for the production of the primary fluorescent film.

When the first layer of the panel is coated with InBO ₃ : Tb phosphor and the second layer is with ZnS: Cu, Al phosphor, the coating amount of this phosphor is reduced when flickering with InBO ₃ : Tb phosphor on the first layer of the panel. The slurry was prepared by changing the amount thereof as shown in Table 2 because it is a factor influencing significantly (as the coating amount of the phosphor increases, it is disadvantageous to the brightness but the flicker decreases a lot). Slurry under each condition was first applied to the panel to prepare a fluorescent film, and then compared to the characteristics thereof, as shown in Table 2 below, the optimum condition was determined as slurry condition 2 excellent in flicker reduction and relative brightness.

Example 1-3 Determination of Optimal Coating Amount of Secondary Phosphor.

Under the condition of slurry condition 2, which is the optimum slurry condition of the primary coating condition, also large influence on the flicker reduction and the brightness of the cathode ray tube to determine the optimum coating amount condition of the secondary phosphor, ie, ZnS: Cu, Al phosphor, for the secondary coating. The slurry was prepared by varying the coating amount of the secondary phosphor as shown in Table 3 below (as the coating amount of the phosphor was increased, it was disadvantageous in brightness but decreased in flicker). Under the above conditions, a double layer of green fluorescent film was formed, a blue and red fluorescent film was formed to fabricate a cathode ray tube, and the characteristics of the cathode ray tube were evaluated, and the results are shown in Table 3.

* The phosphors used in the comparative cathode ray tube are ZnS: Au, Cu, Al

* Cathode ray tubes-1, 2, and 3 are made of double layer green fluorescent film, in which the first layer is InBO ₃ : Tb and the second layer is ZnS: Cu, Al

Compared to the cathode ray tube of the comparative example as shown in the results of Table 3, the cathode ray tube of the present invention shows a 2-5% luminance decrease in terms of brightness, but exhibits a long light emission time of about 10 times or more in terms of afterglow time, thereby causing a flicker phenomenon. It can be seen that this is significantly improved.

When the green phosphor is applied to the panel, first, one phosphor selected from the group of InBO ₃ : Tb, Zn ₂ SiO ₄ : Mn, La ₂ O ₂ S: Tb having long afterglow characteristics is first applied, and then ZnS: By applying a phosphor of Cu, Al, (Au) to make a double-layer (double-layer) it was possible to reduce the flicker phenomenon of the cathode ray tube and to improve the brightness. Compared to the afterglow time of the ZnS: Cu, Al, (Au) phosphor used for a general cathode ray tube of 140 ㎲, the afterglow time when the double layer fluorescent film was manufactured according to the present invention was 1.5 ms, which was about 10 times. Since the abnormal light emission time was long, the flicker phenomenon was remarkably reduced.

Claims (4)

Panel for Cathode Ray Tube with Black Matrix The first layer of green phosphor formed at the site where the black matrix is not formed for the emission of cathode ray tube on the panel is InBO ₃ : Tb, Zn ₂ SiO ₄ : Mn and La ₂ O ₂ S The second layer formed on the green phosphor and the phosphor layer of the phosphor selected from the phosphor group of Tb is composed of a phosphor film of the phosphor selected from the phosphors of ZnS: Cu, Al or ZnS: Cu, Al, Au. Double layer fluorescent film. The double layer fluorescent film for a flickerless cathode ray tube according to claim 1, wherein the amount of the fluorescent material used in the second layer is in the range of 2 to 15 µm. First layer comprising a green phosphor composition selected from the group consisting of InBO ₃ : Tb, Zn ₂ SiO ₄ : Mn, and La ₂ O ₂ S: Tb on the black matrix-free region of the cathode ray tube panel on which the black matrix is formed Forming a second layer comprising a phosphor composition of ZnS: Cu, Al or ZnS: Cu, Al, Au on the first layer; and a method of manufacturing a double layer fluorescent film for a flickerless cathode ray tube . The method for producing a double layer fluorescent film for a flickerless cathode ray tube according to claim 3, wherein the amount of the fluorescent material used for the second layer is in the range of 2 to 15 µm.