JPH0721949A - Projection cathode-ray tube and manufacture thereof - Google Patents

Abstract

PURPOSE:To enhance the brightness by a multilayer interference film and to reduce a time-depending variation in brightness by forming a high refractive index material layer with high conductivity in between the multilayer interference film and a fluorescent material layer. CONSTITUTION:A multilayer interference film 2 consisting of plural layers obtained by alternately stacking a layer H made of a high refractive index material and a layer L made of a low refractive index material is formed on the inner surface of a face glass 1 constituting part of a vacuum envelope, and a high refractive index material layer 3 with high conductivity is formed in the outermost layer. An electrode is arranged in an electrolyte aqueous solution containing a fluorescent material so as to face to the inside of the glass 1 in which the film 2 and the layer 3 are formed, and potential difference is applied between the electrode and the glass 1 to form a fluorescent surface (a fluorescent layer 4) on the inner surface of the glass 1. By forming the layer 3 with conductivity between the film 2 and the layer 4, brightness is enhanced and a time-depending variation in brightness can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type cathode ray tube for enlarging and projecting an image projected on a fluorescent screen onto a front image screen via a projection lens arranged opposite to this fluorescent screen.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 3-36269 discloses an invention for improving the poor light collection efficiency when the light emitted from each monochromatic cathode ray tube in a projection TV set is taken into a projection lens unit.

According to the present invention, in a normal cathode ray tube, the light emitted from the fluorescent screen is in a state close to what is called perfect diffused light, but in the projection TV, the divergence angle of the light emitted from the fluorescent screen is used. Since only those within 30 ° are used and unnecessary light becomes unnecessary, projection is performed by concentrating 30% or more of the total luminous flux emitted from the light emitting point with a fluorescent screen inside a cone with a divergence angle of ± 30 °. It is said that the brightness of the image on the type TV screen can be greatly improved. Furthermore, as this concrete aggregation means,
On the inner surface of the face plate of the cathode ray tube, titanium oxide (Ti
It is described that a multi-layer interference coating in which high refractive index layers made of O2) and low refractive index layers made of silicon oxide (SiO2) are alternately laminated is provided.

Also in the invention of JP-A-61-273837, a high refractive index material layer and a low refractive index material layer are alternately provided between the face glass and the phosphor layer on the inner surface of the face plate of the projection cathode ray tube. There is described a projection-type cathode ray tube having a multilayer interference film formed by stacking layers of tantalum oxide (TaO) (Ta) as a high refractive index material.
2O5) or titanium oxide (TiO2) as a low refractive index material (SiO2) or magnesium fluoride (Mg)
Those using F2) are disclosed.

When a projection-type cathode ray tube provided with these multilayer interference films is used in a projection-type TV, it is possible to greatly improve the brightness in the central part of the screen, but at the peripheral part of the screen, light is not taken into the lens. The brightness remains low because of the inadequacy.

[0006] In US Pat. No. 4,683,398, in order to solve the problem of the peripheral brightness, the inner surface (fluorescent surface) of the face glass has a certain curvature to increase the peripheral light amount. Things are listed.

[0007]

Conventionally, the fluorescent screen of a so-called monochrome cathode ray tube such as a projection type cathode ray tube is generally formed by a sedimentation method or a printing method.

In the precipitation method, a fluorescent substance dispersed in an aqueous potassium silicate solution is put into a bulb, and an appropriate electrolyte (for example, barium acetate or barium nitrate) is further added to the bulb (the inner surface of the face glass). ) Is a method of binding a phosphor by silicic acid polymerization, but in this sedimentation method, the phosphor is deposited on the inner surface of the face glass by its own weight, so there are many voids and the coating density of the phosphor is low. Therefore, in order to obtain the optimum brightness, it was necessary to form a film having a considerable thickness. This is not preferable in the projection type cathode ray tube provided with the multiple interference film in which the reflection on the phosphor screen is increased to improve the brightness.

Further, in the method of forming a fluorescent surface by a printing method represented by screen printing, when the inner surface of the face glass is flat, a fluorescent surface having a high coating density can be obtained, but the inner surface of the face glass has a curvature. However, in the case where the face glass has a frame called a skirt portion around the face glass, there is a problem that the film thickness in the peripheral portion of the face glass becomes extremely thicker than that in the center. .

Further, in the conventional projection type cathode ray tube in which the multiple interference film having a low coating density is formed, the energy of the electron beam directly reaching the glass during the operation of the cathode ray tube becomes large, so that the glass is colored (browning). There is also a problem that the deterioration of luminance is likely to occur due to a large change with time.

The present invention has been made to solve the above-mentioned problems, and in addition to being able to form a fluorescent screen densely and uniformly on the inner surface of the face glass, it also increases the light reflectance on the fluorescent screen. The purpose of this is to obtain a projection-type cathode ray tube in which the brightness is improved by the multiple interference film and the change of this effect with time can be reduced.

A further object of the present invention is to provide a manufacturing method most suitable for manufacturing the above-mentioned projection type cathode ray tube.

[0013]

A projection type cathode ray tube according to claim 1 of the present invention comprises a face glass forming a part of a vacuum envelope, and a phosphor layer formed on an inner surface of the face glass. A multilayer interference film provided between the phosphor layer and the face glass, the multilayer interference film including a plurality of alternating high refractive index material layers and low refractive index material layers, and the multilayer interference film and the fluorescent material. And a high refractive index material layer having conductivity provided between the body layer and the body layer.

According to a second aspect of the present invention, there is provided a method of manufacturing a projection type cathode ray tube, wherein a plurality of alternating layers of a high refractive index material and a low refractive index material layer are provided on an inner surface of a face glass forming a part of a vacuum envelope. A first step of forming a layer, a second step of forming a high refractive index material layer having conductivity in the outermost layer of the plurality of layers, a high refractive index having conductivity and the plurality of layers in an electrolyte aqueous solution containing a phosphor A third step of forming a fluorescent screen on the inner surface of the face glass by arranging an electrode facing the inner surface of the face glass on which the rate material layer is formed and applying a potential difference between the electrode and the face glass Is.

According to a third aspect of the present invention, there is provided a method of manufacturing a projection type cathode ray tube, wherein a plurality of high refractive index material layers and low refractive index material layers are alternately provided on an inner surface of a face glass forming a part of a vacuum envelope. A first step of forming a layer, a second step of forming a conductive high refractive index material layer in the outermost layer of the formed plurality of layers,
Third step of forming a phosphor layer on the inner surface of the face glass on which the plurality of layers and the high refractive index material layer having conductivity are formed by a sedimentation method, the plurality of layers in the aqueous electrolyte solution, high refraction having conductivity An electrode is arranged so as to face the inner surface of the face glass on which the rate material layer and the phosphor layer are formed, and a potential difference is applied between the electrode and the face glass to form a fluorescent surface on the inner surface of the face glass.
It is equipped with steps.

[0016]

The projection type cathode ray tube according to the present invention has a fluorescent screen formed by using a conductive high refractive index material layer provided between the multilayer interference film and the fluorescent layer as an electrode.

In the method of manufacturing a projection cathode ray tube according to the present invention, a conductive high refractive index material layer is provided between the multilayer interference film and the phosphor layer, and the conductive high refractive index material is provided. A fluorescent surface is formed by an electrodeposition method using the layer as an electrode.

[0018]

【Example】

Example 1. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a main part of a face glass of a projection cathode ray tube having a multilayer interference film formed on an inner surface thereof according to an embodiment of the present invention. In the figure, 1 is a face glass forming a part of a vacuum envelope (not shown) of a cathode ray tube, 2 is formed on the inner surface of the face glass 1, and the optical thickness of each film is λh / 4 (here Where λh = λp + λ, λ is the phosphor 4 described later.
, The desired center wavelength selected from the emission spectra of
Is an arbitrary value between 20 and 100 nm. ) Is a multilayer interference film, H is a layer made of a high refractive index material,
L represents a layer made of a low refractive index material. 3 is the outermost layer made of a high refractive index material having conductivity, which is characteristic of the projection cathode ray tube of the present invention, 4 is a phosphor layer, and 5 is energy of an electron beam emitted from an electron gun (not shown). Of the light generated by the excitation of the phosphor layer 4 by the light reflected toward the opposite side of the face glass 1,
It is a metal back layer made of an aluminum vapor deposition film that is directed toward the face glass 1.

In the projection cathode ray tube of this embodiment, the multilayer interference film 2 is formed by tantalum oxide (Ta2O5) (refractive index 2.0 to 2.0).
1) high refractive index material layer H and silicon oxide (Si
O2) (refractive index 1.45 to 1.50) is composed of a total of 12 material layers in which low refractive index material layers L are alternately laminated, and the outermost layer 3 is made of indium oxide (In2O3) (refractive index 2. 0 to 2.1) and a high-refractive-index material layer having conductivity, and a phosphor layer 4 is formed by using an electrodeposition method (electrophoresis method) described below,
A high-density fluorescent film having the above-mentioned λh of 600 nm is formed on the face glass 1.

The phosphor layer 4 is made of terbium (T
The center wavelength λ activated in b) is 544 to 545 nm.
Which is a green light emitting phosphor.

FIG. 2 is a schematic configuration diagram for explaining the electrodeposition method used in this embodiment. In the figure, 6 is a face glass having a multilayer interference film 2 and an outermost layer 3 made of a high refractive index material layer having conductivity, 7 is an electrode, 8 is an electrodeposition tank, and 9 is an electrode in which a phosphor is dispersed. It is a landing liquid, and is composed of the following composition in this embodiment.

Isopropyl alcohol: 1000 ml Lanthanum nitrate: 2.48 g Pure water: 16.5 ml Y2SiO5, Tb phosphor: 0.638 g

The electrodeposition method is an application of the electrodeposition coating technique, and is a multivalent ion (in the present embodiment, which charges the surface of the phosphor particles).
This is a method of forming fluorescent film on the face glass by migrating the phosphor particles in the solution by applying a DC voltage with the face glass as the cathode in a solution containing lanthanum La3 +). And a dense fluorescent film can be obtained.

Table 1 shows the characteristics of the projection type cathode ray tube in which the fluorescent film is produced in this manner. As is clear from this table, in the projection cathode ray tube of the present embodiment, as compared with the projection cathode ray tube in which the fluorescent film is formed by the conventional sedimentation method, a thin fluorescent film having a thin film thickness and a dense face can be obtained. It was confirmed that the brightness (luminance) in the normal direction of the glass was improved by about 10%, and it was also confirmed that the change in the luminance with time was small.

[0025]

[Table 1]

Example 2. In this embodiment, the multilayer interference film 2 and the outermost layer 3 (equivalent to those of the first embodiment) are formed on the face glass 1 and the fluorescent screen is formed by the conventional sedimentation method, and then as shown in FIG. A fluorescent substance is electrodeposited by applying an electric field to. Also in this embodiment, as compared with the projection type cathode ray tube in which the fluorescent film is formed by the conventional sedimentation method, a dense fluorescent screen having a thin film thickness is obtained, and the brightness (luminance) in the normal direction of the face glass is improved. I also confirmed that. (The characteristics are shown in Table 1.)

Example 3. Although the outermost layer 3 is made of indium oxide (In2O3) in Examples 1 and 2, tin oxide (Sn) is used as the outermost layer 3 in this example.
O2) (refractive index 2.0-2.1) is used,
A projection type cathode ray tube having a multilayer interference film of 565 to 570 nm. (The manufacturing method is the same as in Example 1.)

Example 4. As a fourth embodiment, a projection type cathode ray tube is constructed by using Al (aluminum) -doped ZnO (refractive index 2.0 to 2.1) as the outermost layer 3. (The manufacturing method is the same as in Example 1.)

Table 2 shows the characteristics of the projection cathode ray tubes obtained in Examples 3 and 4.

[0030]

[Table 2]

As is clear from Table 2, in each of the projection type cathode ray tubes of Example 3 and Example 4, a dense phosphor screen having a thin film thickness can be obtained as compared with the conventional precipitation method. It is understood that the brightness (luminance) in the normal direction of the face glass is improved, and the temporal change of the luminance is reduced.

As can be understood from the above description, in the conventional projection cathode ray tube, the outermost layer 3 is made of tantalum oxide (Ta2).
O5), titanium oxide (TiO2) and other non-conductive material layers, the multi-layer interference film formed on the face glass as in the present invention functions as an electrode to form a fluorescent screen by electrodeposition. Cannot be formed, and the phosphor screen cannot be formed with high density.

Further, in order to investigate the effect of the outermost layer having conductivity on the change characteristic of luminance with time, the present inventor evaluated using a conventional multilayer interference film made of tantalum oxide (Ta2O5). As a result, it was confirmed that the relative brightness after 10,000 hours passed was 60%. This means that the outermost layer having conductivity has improved the deterioration characteristic of luminance. This means that the charge due to the electron beam directly passing through the gap of the phosphor screen is released by this conductive layer. It is considered that the coloring prevents the glass from coloring (blowing).

In each of the above-described embodiments, the case where the terbium (Tb) -activated green phosphor is used as the phosphor has been described, but the present invention is not limited to this, and the blue phosphor or the red phosphor is used. A body may be used, and λh is selected according to the emission main wavelength of the selected phosphor, and if a multilayer interference film and a high refractive index layer having conductivity are formed in accordance with this λh, substantially the same as in the above-mentioned embodiment. Of course, it is effective.

[0035]

As described above, according to the projection type cathode ray tube and the method for manufacturing the cathode ray tube of the present invention, the high refractive index material layer and the low refractive index material layer are composed of a plurality of alternating layers. Since a high refractive index material layer having conductivity is formed between the multilayer interference film and the phosphor layer,
In addition, it is possible to obtain a projection type cathode ray tube in which the change in luminance with time is small.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a face glass of a projection cathode ray tube having a multilayer interference film according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an example of an electrodeposition method used in Example 1 of the present invention.

FIG. 3 is a schematic configuration diagram showing an example of an electrodeposition method used in Example 2 of the present invention.

[Explanation of symbols]

1. Face glass 2. Multilayer interference film 3. 3. High refractive index material layer having conductivity (outermost layer) 4. Phosphor layer 5. Metal back layer 6. Face glass with a multilayer interference film and the outermost layer formed on the inner surface 7. Electrode 8. Electrodeposition method 9. Electrodeposition liquid with phosphor dispersed

Claims (4)

[Claims] 1. A face glass forming a part of a vacuum envelope, a phosphor layer formed on an inner surface of the face glass, and a high-density glass provided between the phosphor layer and the face glass. A multilayer interference film composed of a plurality of alternating layers of a refractive index material layer and a low refractive index material layer, and a conductive high refractive index material layer provided between the multilayer interference film and the phosphor layer And a projection cathode ray tube. 2. A first step of forming a plurality of alternating layers of a high refractive index material layer and a low refractive index material layer on an inner surface of a face glass constituting a part of a vacuum envelope, the outermost layer of the plurality of layers being formed. Second step of forming a conductive high refractive index material layer, facing the inner surface of the face glass on which the plurality of layers and the conductive high refractive index material layer are formed in an electrolyte aqueous solution containing a phosphor A method for manufacturing a projection type cathode ray tube comprising a third step of forming an fluorescent surface on an inner surface of a face glass by disposing electrodes and applying a potential difference between the electrodes and the face glass. 3. A first step of forming a plurality of alternating layers of a high-refractive index material layer and a low-refractive index material layer on an inner surface of a face glass which constitutes a part of a vacuum envelope, and the first step of forming the plurality of layers. Second step of forming a conductive high refractive index material layer on an outer layer, and forming a phosphor layer on the inner surface of the face glass on which the plurality of layers and the conductive high refractive index material layer are formed by a sedimentation method 3 steps, an electrode is arranged in the aqueous electrolyte solution so as to face the inner surface of the face glass on which the above-mentioned plurality of layers, the conductive high refractive index material layer and the phosphor layer are formed, and a potential difference between the electrode and the face glass. To form a fluorescent screen on the inner surface of the face glass by applying
A method of manufacturing a projection-type cathode ray tube including steps. 4. The high refractive index material layer having electrical conductivity,
2. The projection cathode ray tube according to claim 1, which is made of at least one material selected from indium oxide, tin oxide, and Al-doped zinc oxide.