JP3323665B2 - Manufacturing method of color cathode ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a color cathode ray tube having a color filter between a face plate and a phosphor layer.

[0002]

2. Description of the Related Art A color cathode ray tube has a structure shown in FIG. 1 comprising a three-electron gun 5, a deflection coil 4, a shadow mask 3, and a phosphor screen 2 (red, blue, and green light emitting phosphor dots).

A conventional color cathode ray tube having a color filter is disclosed in, for example, Journal Electrochemical Society, Vol. 128, No. 11, pp. 2395 to 2401, 1981 (J. Electrochem. Soc., Vol. 1).
28 No.11 PP.2395-2401 (1981)), it has a phosphor screen structure as shown in FIG.

The phosphor screen shown in FIG. 2 is formed by forming color filters 8, 9, 10 in contact with the inner surface of the face plate 1, and forming phosphor layers 11, 12, 13 on the color filters.

Here, the color filter is formed using a color filter-forming photosensitive pigment coating composition containing pigment particles of the same color as the phosphor, a water-soluble polymer, an alkali salt of dichromate and a dispersant.

[0006]

However, in such a method for forming a color filter, ultraviolet rays are absorbed by the pigment during exposure, and the ultraviolet ray transmission is reduced, so that the exposure at the interface in contact with the face plate becomes insufficient. However, there is a problem that the color filter dots in the exposed portions fall off during the development by, and it becomes difficult to form a pattern. This defect is particularly noticeable in red and green filters.

It is an object of the present invention to provide a method for manufacturing a color cathode ray tube in which color filter dots are less likely to fall off.

[0008]

The above objects can be attained by adding a xanthene dye to a conventional photosensitive pigment coating composition for forming a color filter at least when forming red and green color filters.

Here, the color filter and the phosphor layer can be formed by a conventionally known method in which the color filter and the phosphor layer are separately formed by lithography twice. Also, other methods can be used. For example, a method in which a color filter and a phosphor layer are formed at one time by one lithography as described in Japanese Patent Application No. 5-82935 can be used.

[0010] Further, a xanthene-based dye may be further included during the formation of the blue color filter.

The xanthene dyes include erythrosine, fluorescein, eosin, rhodamine B, rhodamine 6G and rose bengal.

As the water-soluble polymer, polyvinyl alcohol can be used, and those having a cloud point in the range of 15 to 45 ° C. are preferable.

[0013]

The xanthene dye acts as a spectral sensitizer for sodium dichromate as a sensitizer in the photosensitive pigment coating composition for forming a color filter, and the photosensitive wavelength range is longer than the absorption wavelength of the pigment. It is presumed to be shifted to.

Hereinafter, the operation of the present invention will be described in more detail focusing on the problems of the prior art. First, in the prior art, a transparent red pigment filter coating film made of ferric oxide (red iron red pigment) fine particles does not transmit light having a short wavelength of 450 nm or less. Also, a transparent green pigment filter coating film composed of fine particles of a solid solution of cobalt oxide and zinc oxide (cobalt green green pigment) also does not transmit light having a short wavelength of 400 nm or less. The photosensitizer, sodium dichromate, is exposed only to ultraviolet light near 365 nm and insolubilized to form a pattern. Therefore, a pattern cannot be formed without being exposed to light having a long wavelength of 500 nm or more passing through the red and green filters.

From this, it can be seen that the conventional problems can be solved if there is a photosensitive agent which is insensitive and insoluble with light of 500 nm or more.

Therefore, by adding a xanthene dye to a photosensitive pigment coating composition for forming a color filter as in the present invention, spectral sensitization that shifts the photosensitive wavelength range to 500 nm or more becomes possible.

The mechanism of this spectral sensitization is that the xanthene dye absorbs light and reacts with polyvinyl alcohol to produce a leuco body of the dye, which reduces hexavalent chromium of sodium dichromate to trivalent chromium, It is considered that trivalent chromium is coordinated with polyvinyl alcohol, crosslinks between the polymers, and becomes insoluble.

Since the xanthene dye is water-soluble,
There is no reduction in the luminance of the phosphor due to the removal of the xanthene-based dye from the color filter during development with water.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments.

Example 1 A pigment paint having the following composition 1 was prepared comprising ferric oxide, polyvinyl alcohol, sodium dichromate, and a dispersant.

Composition 1 Ferric oxide 7.2 wt% polyvinyl alcohol ...... 3.6 Sodium dichromate ............ 0 .25 Dispersant ............ 0.072 Water ... Residue Fluorescein, erythrosine, eosin, rhodamine B, rhodamine 6G and rose bengal dye were added to the paint of composition 1 above. 2 wt% for polyvinyl alcohol
% Paints were prepared. For comparison, paints were prepared, each containing no dye, and adding 2 wt% of methylene blue to polyvinyl alcohol as another dye.

After the paints are spin-coated on a glass substrate, light from an ultra-high pressure mercury lamp is passed through a mask for 2 hours.
Stepwise exposure was performed for 5, 50, and 100 seconds. Then, it was spray-developed with water. The coating film containing fluorescein, erythrosine, eosin, rhodamine B, rhodamine 6G and rose bengal dye formed a red filter pattern by exposure for 50 or 100 seconds. However, the dye-free, methylene blue-containing coating did not form red filter dots at all exposure times.

Table 1 summarizes the results.

Table 1 Types and existence of dyes Exposure time (seconds) 25 50 100 None × × × Erythrosin × 〇 〇 Fluorescein × 〇 〇 Eosin × 〇 ロ ー ダ Rhodamine B × 〇 〇 Rhodamine 6G × 〇 〇 Rose Bengal × 〇 メ チ レ ン Methylene blue × × × ×: Drop off of filter dot 〇: Formation of filter dot Example 2 Cobalt blue (CoO.Al ₂ O ₃ ), polyvinyl alcohol,
A pigment coating composed of sodium dichromate and a dispersant having the following composition 2 was prepared.

Composition 2 Cobalt Blue (CoO · Al ₂ O ₃ ) 7.2 wt% Polyvinyl Alcohol 3.6 Sodium Bichromate ……………… 0.25 Dispersant 0.072 Water ...... Residue Fluorescein, erythrosine, eosin, rhodamine B, rhodamine 6G, rose 2 wt% of Bengal dye to polyvinyl alcohol
% Paints were prepared. For comparison, paints without pigments and with 2% by weight of methylene blue added to polyvinyl alcohol as other pigments were prepared.

After the coating materials are spin-coated on a glass substrate, light from an ultra-high pressure mercury lamp is applied through a mask for 2 hours.
Stepwise exposure was performed for 5, 50, and 100 seconds. Then, it was spray-developed with water. The coating film containing fluorescein, erythrosine, eosin, rhodamine B, rhodamine 6G and rose bengal dye formed a blue filter pattern by exposure for 25 seconds. However, the methylene blue-containing coating without dye did not form blue filter dots at an exposure time of 25 seconds. In the case of containing a xanthene dye, a blue filter dot was formed with a half exposure time.

Table 2 summarizes the results.

Table 2 Types and existence of dyes Exposure time (second) 25 50 100 None × 〇 〇 Erythrosin 〇 〇 〇 Fluorescein 〇 〇 〇 Eosin 〇 〇 ロ ー ダ Rhodamine B 〇 〇 〇 Rhodamine 6G 〇 〇 〇 Rose Bengal 〇 〇 メ チ レ ン Methylene blue × 〇 〇 ×: Filter dot drop off 〇: Filter dot formation Example 3 Cobalt green (CoO · 8ZnO), polyvinyl alcohol,
A pigment coating having the following composition 3 and comprising sodium dichromate and a dispersant was prepared.

Composition 3 Cobalt Green (CoO.8ZnO) 7.2 wt% Polyvinyl Alcohol 3.6 Sodium Bichromate ... 0 .25 Dispersant ............ 0.072 Water ... Residue Fluorescein, erythrosine, eosin, rhodamine B, rhodamine 6G and rose bengal dye were added to the paint of composition 3 above. 2 wt% for polyvinyl alcohol
% Paints were prepared. For comparison, paints were prepared, each containing no dye, and adding 2 wt% of methylene blue to polyvinyl alcohol as another dye.

After the paints are spin-coated on a glass substrate, light from an ultra-high pressure mercury lamp is applied through a mask for 2 hours.
Stepwise exposure was performed for 5, 50, and 100 seconds. Then, it was spray-developed with water. The coating film containing fluorescein, erythrosine, eosin, rhodamine B, rhodamine 6G and rose bengal dye formed a green filter pattern by exposure for 50 or 100 seconds. However, the dye-free, methylene blue-containing coating did not form green filter dots at all exposure times.

Table 3 summarizes the results.

Table 3 Types and presence or absence of dye Exposure time (seconds) 25 50 100 None × × × Erythrosin × 〇 〇 Fluorescein × 〇 〇 Eosin × 〇 〇 Rhodamine B × 〇 〇 Rhodamine 6G × 〇 ロ ー ズ Rose Bengal × 〇 メ チ レ ン Methylene blue × × × ×: Filter dot drop off 〇: Filter dot formation Example 4 A red filter dot was formed on the inner surface of the face plate of a color CRT at the position where the red phosphor dot adhered by the method described in the above example. . Then, blue filter dots and green filter dots were formed from the blue pigment paint and the green pigment paint through the same photolithography process. Thereafter, red phosphor dots, blue phosphor dots, and green phosphor dots of the same color were formed on the red, blue, and green filter dots, respectively, by an ordinary slurry method. Thereafter, an acrylic layer as an intermediate film was applied to form a metal back layer of aluminum. In this way, a target phosphor screen composed of a laminate of each color filter and each color phosphor dot layer was obtained on the inner surface of the face plate. Thereafter, panel baking was performed, frit baking was performed on the face plate portion and the funnel portion together, and a color cathode ray tube was manufactured through a process of attaching an electron gun.

Example 5 A pigment coating having the following composition 4 was prepared from ferric oxide, polyvinyl alcohol (cloud point: 40 ° C.), sodium dichromate, a dispersant, and fluorescein.

Composition 4 Ferric oxide 7.2 wt% polyvinyl alcohol (cloud point: 40 ° C.) 3.6 Sodium dichromate ... 0 .25 Dispersant 0.072 Fluorescein ...... 0.072 Water ... Residual red light emitting phosphor powder, polyvinyl alcohol , Sodium dichromate, and a dispersant, the following phosphor composition 5 was prepared.

Composition 5 Red Light Emitting Phosphor Powder 25 wt% Polyvinyl Alcohol 1.75 Sodium Bichromate ............................ 0.123 Dispersant ... 0.035 Water ... Residual composition 4 was spin-coated on a glass plate to form a pigment filter coating. . Next, the phosphor coating composition 5 was spin-coated thereon to form a two-layer laminate. Light from an ultra-high pressure mercury lamp was exposed through a mask for 50 seconds. Then, it was spray-developed with water. A red light emitting phosphor pattern with a red filter was formed.

The present invention can be applied not only to the above-mentioned fluorescent screen but also to the formation of blue, green and red filter patterns formed on another transparent substrate.

[0037]

According to the present invention, the drop of the color filter dots is reduced, and the production yield of the color cathode ray tube can be improved.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a color cathode ray tube.

FIG. 2 is an enlarged sectional view of a fluorescent screen of the color cathode ray tube of FIG.

[Explanation of symbols]

1: Face plate 8: Blue pigment filter dot 2: Phosphor screen 9: Green pigment filter dot 3: Shadow mask 10: Red pigment filter dot 4: Deflection coil 11: Blue light emitting phosphor dot 5: Three electron gun 12: Green light emission Phosphor dot 6: Funnel 13: Red light-emitting phosphor dot 7: Black matrix

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Osamu Sasaya 3300 Hayano, Mobara City, Chiba Pref.Electronic Device Division, Hitachi, Ltd. (56) References JP-A-52-77578 (JP, A) JP-A-50-125722 (JP, A) JP-A-60-31588 (JP, A) JP-A-6-295683 (JP, A A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01J 9/227 H01J 29/18

Claims (4)

(57) [Claims] 1. A phosphor screen structure comprising a laminate in which a color filter pattern layer and a phosphor pattern layer of the same color as the color filter pattern layer are laminated in this order on the inner surface of the face plate by exposure and development with water. In the method for producing a color cathode ray tube having a step of performing, the photosensitive pigment coating composition used for forming the color filter includes at least pigment particles of the same color as the phosphor laminated on the color filter, a water-soluble polymer, and dichromic acid. It comprises an alkali salt and dispersing agent, and at least the red and green of the photosensitive pigment coating composition used for forming a color filter is Nde contains further a xanthene dye, the color
Lamination of filter pattern layer and phosphor pattern layer of the same color
A method for producing a color cathode ray tube, wherein the body is formed by a single exposure and development with water . 2. The method for producing a color cathode ray tube according to claim 1, wherein the photosensitive pigment coating composition used for forming a blue color filter further contains a xanthene dye. 3. The above xanthene dye is erythrosine, fluorescein, eosin, rhodamine B, rhodamine 6
3. The method for producing a color cathode ray tube according to claim 1, wherein the color cathode ray tube is any one selected from the group consisting of G and Rose Bengal. 4. The method for producing a color cathode ray tube according to claim 1, wherein the water-soluble polymer is polyvinyl alcohol.