JP2000044942A - Phosphor, surface treatment thereof and formation of color cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a color cathode ray tube having a good display quality by improving the smoothness of the outline of the phosphor layer. SOLUTION: The surface of a phosphor particle 1, which is a component of a phosphor slurry, is previously covered with an organic compound film 5 having an absorption against an irradiated ultraviolet ray 3 having a wavelength of about 300 to 380 nm. A phosphor slurry is formed using this surface- treated phosphor, and patterning is carried out to reduce a scattered ultraviolet ray 46 which scatters at the phosphor surface. This yields a phosphor layer with an ideal form and a good outline smoothness. Furthermore, achievement of a good form of the phosphor layer leads to improvement of display quality of a color cathode ray tube containing the phosphor layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor used for forming a phosphor screen of a color cathode ray tube, a method for treating the surface of the phosphor, and a technique for forming a color cathode ray tube using the phosphor. It is.

[0002]

2. Description of the Related Art In recent years, with the spread of the Internet and the spread and enhancement of image processing software, market demands for higher definition have been increasing, particularly in the field of display monitors for personal computers. In order to realize the high definition of the display monitor, it is indispensable to miniaturize the fluorescent screen of the color cathode ray tube.

One of the major obstacles to miniaturizing the fluorescent screen of a color cathode ray tube is the problem of sharpness of the edge of the phosphor layer. That is, when an attempt is made to form a phosphor layer having a line pattern L shape as shown in FIG. 11A, the end portion of the pattern does not have an ideal shape (a shape corresponding to the line pattern L), and eventually , Phosphor layer K1
However, there is a problem in that the contour is lacking in smoothness, for example, a part of the contour protrudes from the ideal contour.

[0004] The tendency is not limited to the line pattern, and as shown in FIG.
The same applies to the case (1). Even if the phosphor layer K2 is to be patterned into the shape of the dot pattern D, the contour does not become an ideal contour, a part of the contour protrudes, and the contour is not smooth.

[0005] When an attempt is made to form a fine phosphor screen in a state in which an inaccurate contour pattern as described above is formed,
The following inconveniences occur. First, as shown in FIG. 12A, each of blue, green, and red is provided between black stripes BL on the inner surface side of a face panel in which black stripes BL made of a black body absorbing layer are arranged at regular intervals. In the case where the phosphor layers b1, g1, and r1 that emit light in a color are formed in a line shape, if a part of the phosphor layer protrudes into the arrangement region of the phosphor layer of another color, color mixing failure occurs at the portion (color mixture) The part where the defect occurred is circled.)

Further, as shown in FIG. 12B, even when the phosphor layer is formed as a dot pattern, an opening A having a shape corresponding to the dot pattern opened in the black body absorbing layer B is formed. Even if the phosphor layers b2, g2, and r2, which emit light of blue, green, and red, are formed in the same shape as the opening A, a part of the phosphor layer is inaccurate due to the inaccurate outline. In some cases, the color spilled out and a color mixture defect occurred (a portion where the color mixture defect occurred was surrounded by a circle).

Therefore, it can be seen that it is very important to form a pattern of the phosphor layer having a smooth contour in order to form a fine phosphor screen.

In Japanese Patent Publication No. 61-46512,
As an approach from the phosphor side to this problem, the phosphor surface is treated with silicon dioxide, an aluminum compound, a zinc compound, and the like, and the adhesive force of the phosphor particles to the glass surface in the unexposed portion and the glass surface in the exposed portion. A method for improving the cleaning property of the phosphor in the unexposed part during development by optimizing the method is disclosed.

The method is effective for improving the cleaning property of the phosphor, and is also effective for reducing the above-mentioned color mixing failure. However, since the substance for treating the phosphor surface is an inorganic substance, it remains on the phosphor surface, and such an inorganic substance is not transparent to an electron beam, so that the use efficiency of the electron beam is reduced and the luminance is reduced. In particular, silicon dioxide-based surface treatments, which are generally widely performed, are such that silicon dioxide is an insulator, so that when irradiated with an electron beam, the phosphor is charged on the surface of the phosphor and prevents the subsequent penetration of electrons. There is also a problem that the use efficiency of the electron beam is reduced and the luminance is reduced.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems. In forming a phosphor layer having a smooth contour, it can be completely decomposed and removed in a heat treatment step. A phosphor surface treatment method that does not adversely affect the emission characteristics of the phosphor and does not cause deterioration of the characteristics of the color cathode ray tube due to long-time electron beam irradiation, and a phosphor obtained by the surface treatment. ,
An object of the present invention is to provide a method for forming a color cathode ray tube using the phosphor.

[0011]

The phosphor according to the present invention is obtained by coating the surface of the particles of the phosphor with an organic compound capable of absorbing exposure ultraviolet rays used for photosensitive curing of a photosensitive resist. .

In the phosphor according to the present invention, the organic compound used for coating the surface is made water-insoluble.

Further, in the phosphor according to the present invention, an organic compound used for coating the surface of the phosphor is provided at a wavelength of 300 nm to 38 nm.
It has a characteristic of absorbing exposure ultraviolet light near 0 nm.

The surface treatment method for a phosphor according to the present invention is a method for obtaining a phosphor whose surface is coated with an organic compound as described above, wherein the organic compound is dissolved in an organic solvent to form a solution. Performing a step of uniformly dispersing the phosphor particles in the solution, and then filtering to obtain a filtration residue, drying the filtration residue, and forming a crystal comprising the organic compound on the phosphor surface. The method includes a step of depositing or forming a monomolecular film of the organic compound on the surface of the phosphor to obtain the phosphor covered with the coating of the organic compound.

Further, the method of forming a color cathode ray tube according to the present invention includes a step of forming a phosphor screen using a phosphor whose surface is coated with an organic compound.

Further, the method for forming a color cathode ray tube according to the present invention includes a step of forming a phosphor screen using the phosphor surface-treated by the phosphor surface treatment method as described above.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 In the present invention, a coating that absorbs light having a wavelength required for exposure is formed on the surface of the phosphor particles to be used, and ultraviolet light scattered from the phosphor surface is reduced, thereby improving the sharpness of the phosphor layer. (Hereinafter, those with excellent contour smoothness are expressed as good sharpness, and those lacking smoothness are expressed as poor sharpness).

FIG. 1 is a view showing the relative intensity of the spectrum of light emitted from an ultraviolet exposure lamp (high-pressure mercury lamp) generally used for forming a fluorescent screen at a wavelength of about 200 nm to about 600 nm. As shown in this figure, this lamp has several emission lines between 300 nm and 600 nm. Among these emission lines, light effective for exposure and curing of a water-soluble photosensitive resist that can be used for forming a phosphor layer, such as polyvinyl alcohol-hexavalent Cr, has a wavelength of about 300 nm to 380 nm. Light.

FIG. 2A is a view schematically showing a state of exposure at the time of patterning a general phosphor layer. In FIG. 2A, reference numeral 1 denotes a phosphor particle contained in the phosphor layer, 2 denotes a desired exposure area in a line pattern, and 3 denotes a phosphor layer located in the desired exposure area 2. Exposure ultraviolet light (wavelength 300 nm to 380 n)
m) and 4a denote scattered ultraviolet rays which are projected out of the desired exposure area 2 and scattered when the phosphor particles 1 are irradiated with the exposure ultraviolet rays 3, respectively. When the surface of the phosphor particles 1 is exposed without performing any processing as in the related art,
Large scattered ultraviolet rays 4a are generated, and as a result, only a phosphor layer with poor sharpness as shown in FIG. 11 can be obtained.

However, as shown in FIG. 2 (b), an organic compound film 5 that absorbs light having a wavelength of 300 nm to 380 nm is formed on the surface of the phosphor particles 1, and the scattered ultraviolet light 4b Can be reduced to a smaller value, the exposure and hardening of the photosensitive resist outside the desired exposure region 2 can be suppressed, and the phosphor layer can be patterned more sharply. The inventor has found this.

The effect of reducing the scattered ultraviolet light is shown in FIG.
As shown in (1), the same organic compound 5a can be expected to be dissolved or dispersed in the phosphor slurry (phosphor suspension 1 comprising the phosphor particles 1 and the photosensitive resist) layer 8 used in forming the phosphor layer. However, in this case, since the organic compound 5a is present at random in the phosphor slurry layer 8, the intensity of the transmitted ultraviolet light 3a required for curing the photosensitive resist in the desired exposed region 2 is also reduced, which is desirable. Absent. In this case, it is important to reduce only the intensity of the scattered ultraviolet light scattered on the phosphor surface. In FIG. 3A, reference numeral 6 denotes a face panel constituting a color cathode ray tube, and 7 denotes a face panel.
Shows a patterned black body absorbing layer on the inner surface side.

On the other hand, as shown in FIG. 3 (b), the surface of the phosphor particles 1 is coated with an organic compound film 5 capable of absorbing the exposure ultraviolet light 3, and the phosphor particles 1 are used. When the phosphor slurry layer 8 is formed, the intensity of the exposure ultraviolet light 3 is hardly reduced.
It is possible to sufficiently secure the intensity of the transmitted ultraviolet light 3b necessary for curing the photosensitive resist located in the desired exposure region 2. From this, it can be seen that the formation of the organic compound film 5 on the surface of the phosphor particles 1 is effective in preventing the exposure ultraviolet light 3 from scattering and in ensuring the intensity of the transmitted ultraviolet light 3b.

Next, the substance to be the organic compound film 5 and the method for forming the organic compound film 5 on the surface of the phosphor particles 1 will be described. In the present invention, for example, 4,4′-bis (diethylamino) benzophenone represented by the structural formula in FIG. 4 can be used as the organic compound covering the surface of the phosphor particles 1. As this organic compound, a water-insoluble substance is used.

FIG. 5 shows the absorption spectrum of this organic compound 4,4'-bis (diethylamino) benzophenone in the ultraviolet region. As can be seen from this figure, 4,4'-
Bis (diethylamino) benzophenone is 3 in the ultraviolet region.
It has broad absorption around 00 nm to around 380 nm, and this wavelength range coincides with the wavelength range of the above-mentioned exposure ultraviolet light.

Next, a technique for coating the surface of the phosphor particles 1 with a film made of the above organic compound (hereinafter referred to as a phosphor surface treatment method) will be described. First, a 0.5 mol / l alcohol solution of the organic compound 4,4′-bis (diethylamino) benzophenone was prepared. Then, for 1 kg of the green phosphor (ZnS: Cu, Al),
The above alcohol solution is added at a ratio of 3 liters, stirred well, and sufficiently dispersed to obtain a dispersion. At this time, if dispersion is not sufficient by stirring alone, means such as ultrasonic dispersion may be used in combination.

Subsequently, the dispersion is filtered using qualitative filter paper or the like, and the residue is dried to precipitate crystals of the organic compound on the surface of the phosphor particles.
Can be obtained. Here, the alcohol solution concentration of the above compound was adjusted to 0.02 mol.
When the concentration is set to be as low as about 1 / l, the compound adsorbs a single molecule on the phosphor surface and is fixed on the phosphor surface without forming a crystal to form a monomolecular film.

Next, a phosphor slurry is prepared using the phosphor particles 1 obtained as described above. In the first embodiment, green phosphors such as ZnS, Cu,
Al is used. The composition of the phosphor slurry is ZnS: C
u, Al (30% by weight), nonionic dispersant (0.1% by weight), polyvinyl alcohol (3% by weight), sodium dichromate (0.3% by weight), and water (remainder). .

As described above, since the water-insoluble substance is used as the organic compound film 5 for coating the surface of the phosphor particles 1, the elution of the organic compound into the phosphor slurry is suppressed. Is possible. Further, by making the organic compound used in the embodiment of the present invention hydrophobic, it is possible to prevent water molecules from entering between the organic compound and the phosphor surface. Therefore, in the phosphor slurry, the organic compound film 5 can be stably fixed on the surface of the phosphor particles 1 without the presence of a special binder for binding the organic compound to the phosphor surface or a sensitive group. It is possible to put.

For comparison, a phosphor slurry having the same composition was prepared by using the same phosphor whose surface was not covered with the film made of an organic compound as described above. A striped phosphor layer was formed by a conventionally known exposure-development method.

Here, two kinds of phosphors as described above (a phosphor subjected to a surface treatment and a phosphor not subjected to a surface treatment) are used.
To clarify the effect of the phosphor layer on sharpness, FIG.
As shown in the figure, the maximum stripe width W1 and the minimum stripe width W2 of the stripe-shaped phosphor layer 9 were measured, and the sharpness of the phosphor layer 9 was evaluated based on the ratio. That is, the sharpness is worse as the ratio of the maximum stripe width W1 / the minimum stripe width W2 is larger, and the sharpness is better as the ratio is smaller. By doing so, the sharpness of the phosphor layer can be numerically evaluated.

Next, a green phosphor layer in the form of a stripe formed by using the phosphor subjected to the surface treatment according to the present invention (with surface treatment) and a stripe formed by using a normal phosphor (without surface treatment) The features of the green phosphor layer will be described with reference to FIG.

As shown in FIG. 7, the stripe-shaped phosphor layer formed by subjecting the surface of the phosphor particles to a surface treatment has a maximum stripe width W1 / minimum stripe width W2 ratio of 1; In contrast, the ratio was 1.21 in the phosphor layer formed using the phosphor not subjected to the surface treatment. Therefore, it can be seen that by performing the surface treatment on the phosphor, the sharpness of the phosphor layer is greatly improved. Further, assuming that the emission luminance of the phosphor screen is 100 when no surface treatment is performed, the emission luminance of the phosphor screen using the phosphor with the surface treatment obtained in the embodiment of the present invention is 99, which is almost the same. It can be seen that the brightness of the image can be secured.

As described above, by covering the surface of the phosphor particles used for forming the phosphor layer with the organic compound film 5, a wavelength of about 300 nm to 380 nm which causes deterioration of the sharpness of the phosphor layer is obtained. By absorbing the exposure ultraviolet light 3 at the surface of the phosphor particles 1, the scattered ultraviolet light 4b is suppressed to a small value, and the photosensitive resist disposed in a region other than the desired exposure region 2 is prevented from being randomly exposed and cured. This makes it possible to improve the sharpness of the obtained phosphor layer.

In the above evaluation examples, only the sharpness of the stripe-shaped phosphor layer has been described. However, the present invention is not limited to this, and the phosphor layer having a dot shape or another shape may be formed. It is needless to say that a similar effect can be obtained by subjecting the surface to a surface treatment.

Further, since the organic compound film 5 formed on the surface of the phosphor particles 1 can be decomposed and removed in a heat treatment step in forming a color cathode ray tube, the phosphor emission characteristics are affected. And no problems such as charging.

Further, since the organic compound covering the surface of the phosphor particles 1 is composed of a water-insoluble and hydrophobic substance, even when the phosphor slurry is prepared, the organic compound is introduced into the phosphor slurry. The organic compound can be fixed on the surface of the phosphor particles in a stable state without elution of the compound, and the phosphor layer can be more sharply patterned.

Further, by preparing a phosphor slurry using the phosphor having been subjected to the surface treatment as described above, and forming a color cathode ray tube using the phosphor slurry, it is possible to obtain a better color mixing defect and the like. Needless to say, it is possible to obtain a color cathode ray tube having a high display quality.

Embodiment 2 Next, a second embodiment of the present invention will be described. In the above-described first embodiment, the formation of the green phosphor layer has been particularly described. In the second embodiment, formation of a blue phosphor layer will be described. In forming the blue phosphor layer, the surface treatment of the phosphor particles is performed in the same manner as in the first embodiment except that the blue phosphor (ZnS: Ag, Cl) is used as the phosphor, and the organic compound film is formed. Thus, phosphor particles having a surface coated were obtained, a phosphor slurry was formed by the same treatment, and the phosphor layer was patterned by an exposure-development method.

FIG. 8 summarizes the characteristics of a striped blue phosphor layer formed by using a phosphor subjected to a surface treatment according to the embodiment of the present invention and a blue phosphor layer without a normal surface treatment. Shown. The ratio of the maximum stripe width W1 / minimum stripe width W2 is 1.05 in the striped blue phosphor layer with surface treatment, whereas the ratio is 1.18 in the blue phosphor layer without surface treatment. It can be seen that, similarly to the case of the green phosphor layer, the sharpness of the phosphor has been greatly improved by performing the surface treatment. Also, the emission luminance of the phosphor was 100% when no surface treatment was performed.
Then, the emission luminance of the phosphor screen using the phosphor with surface treatment obtained in the embodiment of the present invention is 101, and it can be seen that almost the same luminance can be secured.

Embodiment 3 Next, a third embodiment of the present invention will be described. In the first and second embodiments, formation of the green and blue phosphor layers has been described. In the third embodiment, formation of a red phosphor layer will be described. In the formation of the red phosphor layer, the surface treatment of the phosphor particles is performed in the same manner as in Embodiment 1, except that a red phosphor (Y ₂ O ₂ S: Eu) is used as the phosphor. Phosphor particles whose surfaces were coated with a compound film were obtained, a phosphor slurry was formed by the same treatment, and the phosphor layer was patterned by an exposure-development method.

FIG. 9 summarizes the characteristics of a striped red phosphor layer formed by using a phosphor subjected to a surface treatment according to the embodiment of the present invention and a red phosphor layer without a normal surface treatment. Shown. In the striped red phosphor layer with surface treatment, the ratio of the maximum stripe width W1 / minimum stripe width W2 is 1.06, whereas in the red phosphor layer without surface treatment, the ratio is 1.23. It can be seen that, similarly to the case of the green and blue phosphor layers, the sharpness of the phosphor is greatly improved by performing the surface treatment. Also,
The emission luminance of the phosphor was 1 when no surface treatment was performed.
Assuming that the luminance is 00, the light emission luminance of the phosphor screen using the phosphor having the surface treatment obtained in the embodiment of the present invention is 102, which indicates that almost the same luminance can be secured.

The technique in which the surfaces of the phosphor particles are covered with the organic compound film as described in the first to third embodiments is effective for all phosphors used in general color cathode ray tubes. It is very effective in improving the sharpness of the phosphor layer.

Embodiment 4 FIG. Embodiment 1 already described
To 3, the same organic compound (4,4′-
The case where the surfaces of the phosphor particles are coated with bis (diethylamino) benzophenone) has been described. In Embodiment Mode 4, other organic compounds that can be used in a similar manner will be described.

FIG. 10 shows that 4,4′-
3 is a chart showing substance names (compound names) and chemical formulas of substances that can be used in the same manner as bis (diethylamino) benzophenone. The substances shown in this chart, C ₁₂ H ₆ O
_{3, C 5 H 3 NO 4} , C 9 H 11 NO, C 12 H 10 O, C 13
_{H 10 O 2, C 7 H} 6 O 2, C 10 H 8 S, C 9 H 9 N 3,
_{C 10 H 7 N 3, C} 13 H 10 N 2, C 18 H 13 N, C 13 H
₉ N, also other than C ₁₂ H ₁₃ N, can be applied to any water-insoluble organic compound having absorption characteristics of the exposure UV light used in the light-sensitive hardening of the photosensitive resist. Further, a substance having hydrophobicity is more optimal.

[0045]

The effects of the present invention will be described below. According to the present invention, in order to obtain a phosphor screen of a color cathode ray tube, when forming a phosphor slurry, the surface of the particles is coated in advance with a coating of an organic compound having absorption for exposure ultraviolet rays. By using the body,
At the time of patterning the phosphor layer composed of the phosphor slurry,
Scattered ultraviolet light can be suppressed to a small level, and a phosphor layer having a smooth contour and an ideal shape can be obtained.

By being able to pattern the phosphor layer into an ideal shape, it is possible to eliminate color mixing failure and the like.
Furthermore, since the organic compound film on the surface of the phosphor particles can be decomposed and removed in a subsequent heat treatment step, a color cathode ray tube with good display quality can be obtained.

Further, by making the organic compound coating the surface of the phosphor particles a water-insoluble substance, even when the phosphor slurry is adjusted, the organic compound does not elute into the phosphor slurry. In addition, it is possible to fix the organic compound on the surface of the phosphor particles in a stable state, and it is possible to obtain a phosphor layer with better sharpness, and the color cathode ray tube on which the phosphor layer is formed is , It is possible to improve the display quality.

[Brief description of the drawings]

FIG. 1 is a diagram necessary for describing Embodiment 1 of the present invention.

FIG. 2 is a diagram necessary for explaining the first embodiment of the present invention;

FIG. 3 is a diagram necessary for explaining the first embodiment of the present invention;

FIG. 4 is a diagram necessary for explaining the first embodiment of the present invention;

FIG. 5 is a diagram necessary for explaining the first embodiment of the present invention;

FIG. 6 is a diagram necessary for describing the first embodiment of the present invention;

FIG. 7 is a diagram necessary for explaining the first embodiment of the present invention;

FIG. 8 is a diagram necessary for describing Embodiment 2 of the present invention.

FIG. 9 is a diagram necessary for describing Embodiment 3 of the present invention.

FIG. 10 is a diagram necessary for describing Embodiment 4 of the present invention.

FIG. 11 is a diagram necessary for explaining a conventional technique.

FIG. 12 is a diagram necessary for explaining a conventional technique.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 phosphor particles, 2 desired exposure area, 3 exposure ultraviolet light, 3a, 3b transmission ultraviolet light, 4a, 4b scattering ultraviolet light, 5 organic compound coating, 5a organic compound, 6 face panel, 7 black body absorption layer, 8 phosphor slurry layer,
9 Phosphor layer, W1 maximum stripe width, W2 minimum stripe width.

Claims (6)

[Claims] 1. A phosphor characterized in that the surface of the phosphor particles is coated with an organic compound capable of absorbing exposure ultraviolet light used for photosensitive curing of a photosensitive resist. 2. The phosphor according to claim 1, wherein the organic compound is insoluble in water. 3. The organic compound has a wavelength of 300 nm to 380.
The phosphor according to claim 1, wherein the phosphor absorbs exposure ultraviolet light having a wavelength in the vicinity of nm. 4. A step of dissolving an organic compound in an organic solvent to form a solution, a step of uniformly dispersing phosphor particles in the solution, and filtering to obtain a filtration residue; By drying, the crystals of the organic compound are precipitated on the surface of the phosphor, or by forming a monomolecular film of the organic compound on the surface of the phosphor, by the coating of the organic compound A method of treating the surface of a phosphor, comprising a step of obtaining the above-mentioned phosphor coated. 5. A method for forming a color cathode ray tube, comprising the step of forming a phosphor screen using the phosphor according to claim 1. Description: 6. A method for forming a color cathode ray tube, comprising the step of forming a phosphor screen using a phosphor surface-treated by the phosphor surface treatment method according to claim 4.