MXPA99002381A - Catodi rays tube - Google Patents

Abstract

A method for making fluorescent layers for cathode ray tubes (CRT) and a CRT adopting the fluorescent layers is described. In which CRT that has the glass screen with an inner surface on which the cathode ray is irradiated, and a first, second and third fluorescent layers of colored shapes on the inner surface of the glass of the screen, a first filter layer of color is formed between the inner surface and the first colored fluorescent layer, and the second and third colored fluorescent layers contain second and third luminescent pigments or colored, pigmented matches, each, therefore, no process of formation of a protective resin layer and the number of processes required is reduced compared to the case in which red, green and blue filter layers are formed, so that the entire manufacturing process is simplified, and therefore Manufacturing costs are reduced. In addition, the luminance and contrast characteristics of CRT which adopts the fluorescent layers manufactured by such method are improved

Description

CRT BACKGROUND OF THE INVENTION 1. Field of the invention The present invention relates to a cathode ray tube (CRT) and more particularly, to a simplified method for manufacturing a fluorescent layer and a CRT with improved luminance and contrast characteristics, which adopts the fluorescent layer manufactured by this method. 2. Description of the related art With a society which is highly industrialized, the need for a CRT as a screen, which is susceptible to high luminance and high definition, has increased. In order to meet such a need, investigations have been carried out to improve the illumination intensity of the electron beams and to decrease the reflectivity by external light. According to a conventional color CRT, the black matrices which absorb the external light are placed at predetermined intervals on the inner surface of a color CRT screen glass, and layers are interposed REF. 29756 fluorescents between the black matrices, which emit different colors of light through the coalitions with the electron beams. As a method to avoid the reflectivity of the fluorescent layers and to prevent the decrease of reflectivity by external light and to improve contrast and luminance, in U.S. Patent Nos. 5,476,737 and 5,179,318 describe a method for coating a pigment on the surface of a luminescent pigment or phosphor, or a method for forming the red, green and blue filter layers between a panel and a fluorescent layer. However, the method for attaching the fine pigment to the surface of a luminescent pigment can not greatly improve the contrast and luminance characteristics even though the manufacturing process of the CRT is simple. In addition, the resistance of the film of a luminescent pigment decreases during exposure. Meanwhile, the method for forming the filter layers, which provides improved contrast and luminance characteristics, is very complicated and increases manufacturing costs.

BRIEF DESCRIPTION OF THE INVENTION To solve the problems, it is an object of the present invention to provide a simple method for manufacturing fluorescent layers for a cathode ray tube (CRT). Another objective of the present invention is to provide a CRT with improved luminance and contrast characteristics, which adopts the fluorescent layers manufactured by the simple method. To obtain this first objective, a method for manufacturing fluorescent layers for a cathode ray tube (CRT) is provided, comprising the steps of: depositing a base solution and a first color filter solution on an interior surface of the glass screen, dry and then expose the resulting structure in sequence, to form a first color filter layer, - deposit a composition containing a first-colored luminescent pigment on the resulting structure with the first color filter layer, dry, expose and then developing or developing the resulting structure in sequence to form a first colored fluorescent layer; depositing a second colored, pigmented luminescent pigment on the resulting structure with the first colored fluorescent layer, drying, exposing and then revealing the resulting structure in sequence to form a second colored fluorescent layer; and depositing a third colored, pigmented luminescent pigment on the resulting structure with the second fluorescent layer of the color, drying, exposing and revealing the resulting structure in sequence to form a third colored fluorescent layer. To obtain the second objective, a cathode ray tube (CRT) is provided, comprising: a shield glass having an inner surface on which the cathode rays are irradiated; a first, second and third color fluorescent layers formed on the inner surface of the screen-glass, wherein in the first color filter layer is formed between the inner surface and the first colored fluorescent layer, and the second and third layers fluorescent colors contain second and third colored luminescent pigments, pigmented, each.

BRIEF DESCRIPTION OF THE DRAWINGS The above objects and advantages of the present invention will become more apparent when describing in detail a preferred embodiment of the invention with reference to the accompanying drawing, in which: Figure 1 is a sectional view showing one of the fluorescent layers for a cathode ray tube (CRT).

DESCRIPTION OF THE PREFERRED MODALITIES In a method for manufacturing fluorescent layers for a cathode ray tube (CRT) according to the present invention, a first colored fluorescent layer is formed on a first color filter layer which has been previously formed, and a second and third colored fluorescent layers of pigmented luminescent pigments. Preferably, the first filter layer is a blue filter layer. The reasons why the blue filter layer is preferred is that the first color filter layer is the one whose main wavelength affects the contrast and is in the blue wavelength region. Therefore, by adopting the blue filter and a naked luminescent pigment, to which no pigment has been attached, at the same time it minimizes the decreases in the luminance of light emitted from the luminescent pigment and the amount of light reflected by external light, from way that the contrast is improved. It is preferable that the blue filter has a transmittance of 95% or greater. When the luminescent pigment is used alone, on the filter layer, the agglomeration of the luminescent pigments during the recovery of the luminescent pigments in the manufacture of a CRT decreases markedly, so that the recovery efficiency of the luminescent pigments is greatly increased. luminescent pigments. Preferably, the pigmented luminescent pigments are used to form the green and red fluorescent layers, which suppress the reflected light and provide a good balance of appearance with respect to the achromatic tone. Preferably, the pigmented luminescent pigment has a particle size of 0.1-0.5 μm, and most preferably, about 1 μm. In addition, the pigmented luminescent pigments include a red-pigmented luminescent pigment of fine red or a green luminescent pigmented pigment of fine green. Here, the red and green pigments are not limited to a specific pigment. However, preferably, an inorganic pigment of Fe203 is used for the red pigment and an inorganic Co pigment for the green pigment. Next, the method for manufacturing fluorescent layers according to the present invention will be described with reference to FIG. A base solution for forming an underlying layer and a first color filter solution are mixed, and the mixture is deposited on an inner surface of the screen glass 11 of a CRT. Then, the resulting structure is dried and a predetermined area thereof is exposed to selectively form a first color filter layer 14a at the position where the first color fluorescent layer is to be formed. The base solution consists of 0.1-5% by weight of a binder, 0.1-2.5% by weight of a photosensitizer, 0.1-1.0% by weight of a surfactant and one residue of a solvent, based on the total weight of the solution of base. And the first color filter solution consists of 5.0-15% by weight of a pigment, 0.1-5% by weight of a binder, 0.1-4.5% by weight of a photosensitizer, 0.1-1.0% by weight of surfactant and the rest of a solvent, based on the first color filter solution. Here, polyvinyl alcohol is used for the binder, dichromate for the photosensitizer and pure water for the solvent. Then, the luminescent pigment of the first color is deposited on the resulting structure with the first color filter layer 14a and then dried. In addition, the dry structure is exposed and developed to form a first color fluorescent layer 13a. In Figure 1, the reference number 12 represents black matrices. Then, a second colored luminescent pigment with a second colored pigment is deposited on the first colored fluorescent layer 13a and then dried. In addition, the resulting structure is exposed and then developed to form a second color fluorescent layer 13b.

A third colored luminescent pigment with the third color pigment is deposited on the resulting structure with the second colored fluorescent layer 13b, and then dried. Subsequently, the dried structure is exposed and developed to form a third colored fluorescent layer 13c. Preferably, the first color filter layer is a blue filter layer (B) which prevents a decrease in reflectivity and luminance more efficiently compared to filter layers with green and red colors. Preferably, the second colored luminescent pigment with a second colored pigment and the third colored luminescent pigment with a third colored pigment have green and red colors which are good for suppressing the reflected light and in the appearance correction.

Example 1 Pluronic blue (Co) was mixed for a blue pigment, Pluronic L-92 (BASF Co.), sodium dichromate and polyvinyl alcohol to prepare a blue filter solution. The blue filter solution is deposited on an interior surface of the screen glass of a CRT and then dried. Subsequently, the predetermined area of the resulting structure is exposed to form a blue filter layer.

Subsequently ZnS: Ag, Al is deposited for the blue luminescent pigment on the resulting structure, dried, exposed and then developed or developed to form a blue fluorescent layer. Subsequently Y202S: Eu is deposited for a red luminescent pigment, strongly pigmented red, in which the red pigment attached has an inorganic pigment of Fe203 (Dainichi seika, particle size: 0.25 μm) on the blue fluorescent layer, dried , it is exposed and revealed to form a red fluorescent layer. Then, ZnS: Cu, Al is deposited for a green luminescent pigment strongly pigmented green, in which the green pigment bound is Green 3320 (Dainichi seika, particle size: 0.2 μm), on the blue fluorescent layer, dried, it is exposed and revealed to form a green fluorescent layer.

Comparative example 1 Y202S: Eu is mixed separately for a red luminescent pigment with a fine red pigment, ZnS: Cu, Al for a green luminescent pigment with a fine green pigment, and ZnS: Ag, Al for a blue luminescent pigment, with water, alcohol polyvinyl, sodium dichromate and PES, and then stirred for about 5 hours to prepare the red, green and blue fluorescent suspensions. The green fluorescent suspension is deposited on a panel of a CRT, and is exposed and developed to form a green fluorescent layer pattern. The above recess is repeated using the blue and red fluorescent suspensions, respectively, instead of the green fluorescent suspension, to form blue and red fluorescent layer patterns.

Comparative example 2 Fluorescent, green, blue and red layers are formed by the general method in which the green, blue and red filter layers are formed in their entirety. That is, a green filter solution is coated by spinning on a panel of a CRT, and is dried, exposed and then developed to form a green filter layer. Subsequently, a composition containing a green luminescent pigment is coated on the resulting structure by rotation and dried, exposed and then developed to form a green microfilter fluorescent layer. Then, a protective resin layer is formed on the green fluorescent layer. The above process was repeated using a solution of blue filter plus blue luminescent pigment and a red filter solution plus a red luminescent pigment, instead of the green filter solution plus the green luminescent pigment, to form, in sequence, fluorescent layers of blue and green microfilter.

Comparative Example 3 Y202S: Eu was used for a pigmented red luminescent pigment, ZnS: Cu, Al for a pigmented green luminescent pigment and ZnS: Ag, Al for a pigmented blue luminescent pigment, each with fine pigments of approximately 1 μm, to form the red, green and blue fluorescent layers, by a general method. Then, the luminance, color reproduction range and contrast characteristics and other manufacturing characteristics were measured on the panels of each of the CRT manufactured by Example 1 and Comparative Examples 1 to 3. The results are shown in the Table 1. Here, the color reproduction interval indicates the area formed by the color coordinates measured using a colorimeter (MC-100, Minolta Co.).

Table 1 Note: a indicates the number of processes required when the filter layer and the fluorescent layers are exposed at the same time; and b indicates the number of processes when the filter layer and the fluorescent layer are exposed separately.

As can be understood from Table 1, the CRT having the fluorescent layer of Example 1, shows good luminance and contrast characteristics and a wide range of color reproduction range, compared to Comparative examples 1 and 3. Although the luminance and contrast characteristics of the CRT manufactured in Comparative Example 2 are better and the color reproduction thereof is more extensive, Comparative Example 2 requires a large number of processes, so that manufacturing it is complicated by an increase in manufacturing costs. However, in Example 1, the deposition steps of the blue filter solution, drying, exposure and development are added to make only the blue filter layer, the number of processes required is markedly reduced compared to Comparative Example 2 Furthermore, in Comparative Example 2, the protective resin layers are formed in order to prevent each filter layer from being wetted in a different color luminescent pigment suspension. However, such a protective resin layer is not necessary in the present invention. As described above, in the method for manufacturing fluorescent layers according to the present invention, the process of forming a protective resin layer is not necessary and the number of processes required is reduced in comparison with the case in which the red, green and blue filter layers are formed so that the entire manufacturing process is simplified and therefore manufacturing costs are reduced. In addition, the luminance and contrast characteristics of the CRT adopting the fluorescent layers manufactured by such method are improved.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers.

Claims (8)

1. CLAIMS Having described the invention as above, the property is claimed as contained in the following: 1. A method for manufacturing fluorescent layers for a cathode ray tube (CRT), characterized in that it comprises the steps of: depositing a base solution and a first color filter solution on an inner surface of a screen glass, drying and then exposing the resulting structure in sequence to form a first color filter layer, - depositing a composition containing a first luminescent pigment or color phosphor on the structure resulting with the first color filter layer, drying, exposing and then developing or developing the resulting structure in sequence to form a first colored fluorescent layer; depositing a second colored, pigmented luminescent pigment on the resulting structure with the first colored fluorescent layer, drying, exposing and then revealing the resulting structure in sequence to form a second colored fluorescent layer; and depositing a third colored, pigmented luminescent pigment on the resulting structure with the second colored fluorescent layer, drying, exposing and revealing the resulting structure in sequence to form a third colored fluorescent layer.
2. 2. The method according to claim 1, characterized in that the first color filter layer is a blue filter layer, the second and third pigmented colored luminescent pigments are each red and green in color.
3. 3. The method according to claim 1, characterized in that the first colored luminescent pigment is a pure luminescent pigment.
4. 4. The method according to claim 1, characterized in that the pigments attached to the second and third luminescent pigments have a diameter of 0.1-0.5 μm.
5. 5. A cathode ray tube (CRT), characterized in that it comprises: a screen glass having an inner surface on which a ray of cathode ray tubes is irradiated; and a first, second and third color fluorescent layers formed on the inner surface of the screen glass, wherein the first color filter layer is formed between the inner surface and the first colored fluorescent layer, and the second and third fluorescent layers of color contain second and third pigments luminescent of color, pigmented, each one.
6. The cathode ray tube according to claim 5, characterized in that the filter layer is a blue filter layer, and the second and third pigmented colored luminescent pigments are each red and green in color.
7. The cathode ray tube according to claim 5, characterized in that the pigments attached to the second and third colored luminescent pigments have a diameter of 0.1-0.5 μm.
8. 8. The cathode ray tube according to claim 5, characterized in that the first colored fluorescent layer contains a pure luminescent pigment.