JP2002190265A - Cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cathode-ray tube of which a colored film is formed easily by suppressing coagulation of coloring matter in metal alkoxide liquid, and also of which the contrast is enhanced by improving the absorbance of the colored film. SOLUTION: The cathode-ray tube comprises a panel portion for displaying an image, a neck portion for containing an electron gun, and a funnel portion for connecting the panel portion with the neck portion. In the tube, the outer surface on a panel has coloring matter for absorbing light selectively and a colored film including colloidal silica for dispersing coloring matter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cathode ray tube,
In particular, the present invention relates to a cathode ray tube with improved contrast.

[0002]

2. Description of the Related Art A glass envelope of a cathode ray tube comprises a panel section for displaying an image, a neck section provided with an electron gun, and a funnel section connecting the panel section and the neck section.

[0003] An electron beam emitted from an electron gun collides with a phosphor layer formed on the inner surface of the face plate to cause the phosphor to emit light. The portion of the face plate where the pixels are formed is the screen. In order to display a high-definition image, a color cathode ray tube in which the pitch of the phosphor layers is reduced has been provided. As the definition of an image has become higher, it has been required to improve the contrast of the image.

A flat panel type color cathode ray tube having a substantially flat front surface has been widely used as a video tube of a television receiver or a personal computer monitor tube. By making the screen flat, the visibility of the image can be improved.

Since the inside of the glass envelope of the cathode ray tube is substantially in a vacuum state, the thickness of each part of the glass envelope is set to a value that can withstand atmospheric pressure. In particular, in the face plate of the flat panel type cathode ray tube, the thickness of the peripheral portion is larger than the thickness of the central portion.

Therefore, the brightness of the image displayed on the face plate is lower in the peripheral portion than in the central portion of the face plate. Further, since the weight of the phosphor is smaller at the periphery of the screen than at the center of the screen, the luminance is further reduced. A panel having a transmittance of 70% or more is used to prevent a decrease in luminance in the peripheral portion.

[0007]

However, if a panel having a high transmittance is used, the image contrast is deteriorated.

In order to improve the contrast of an image,
There is known a technique for adjusting a spectral transmittance by forming a colored film on the front surface of a panel. It is generally known that a colored film is formed using a sol-gel method. For example, a colored film is formed by applying a mixed solution of a metal alkoxide, alcohol, water, and a dye on the front surface of the panel, and then firing.

Since the dye easily aggregates in the metal alkoxide solution, it has been difficult to maintain the dispersion of the dye in the metal alkoxide solution for a long time. If an aggregated dye exists on the panel surface, light is scattered by the aggregated dye and transparency is impaired. Further, the aggregated dye blurs the image.

On the other hand, if a large amount of a dispersant is added to the mixed solution to suppress the aggregation of the dye, there is a problem that the colored film becomes weak.

[0011]

A cathode ray tube comprising a panel having a plurality of fluorescent films formed on an inner surface thereof, a neck having an electron gun therein, and a funnel connecting the panel and the neck. In forming a colored film on the front surface of the panel using a sol-gel method, a metal alkoxide, a dye,
A liquid mixture containing metal colloid particles, water and alcohol is applied to the front of the panel and fired to form a colored film.

A cathode ray tube comprising a panel portion having a plurality of fluorescent films formed on an inner surface thereof, a neck portion containing an electron gun, and a funnel portion connecting the panel portion and the neck portion. The colored film is made of pigment, SiO ₂ , Al ₂
And at least one kind of fine particles of O ₃ , ZrO ₂ , and TiO ₂ .

By forming a colored film containing metal oxide fine particles, a colored film with less aggregation can be obtained.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a main part of a cathode ray tube according to the present invention.

A glass envelope (bulb) constituting a color cathode ray tube comprises a panel portion 1 disposed on the front side, an elongated neck portion 2, and a funnel portion 3 connecting the panel portion 1 and the neck portion 2. Become.

The panel unit 1 includes a front face plate 1
F and a skirt portion connected to the funnel portion. The face plate 1F, which is a glass substrate, has a screen (screen) 4 on its inner surface and a thin film 5 on its outer surface. The screen 4 is formed by a black matrix layer and red, green, and blue phosphor layers.

An electrode assembly for color selection is mounted inside the panel. The shadow mask structure 6 in FIG. 1 is an electrode structure for color selection. Shadow mask structure 6
Is composed of a shadow mask 6S having a plurality of electron beam passage holes on the face plate 1F side, a mask frame 6F holding the shadow mask 6S, and a spring fixed to the mask frame 6F. The spring is fitted on a stud pin installed inside the panel.

An internal magnetic shield 7 is provided inside the joint between the panel section 1 and the funnel section 3, and the internal magnetic shield 7 shields an external magnetic field. A deflection yoke 8 is arranged outside the joint between the funnel 3 and the neck 2.

The neck portion 2 elongated in the tube axis direction of the cathode ray tube contains an electron gun 9. The electron gun 9 emits three electron beams Be from three in-line arranged cathodes toward the inner surface of the face plate.

The three electron beams Be (only one is shown in FIG. 1) emitted from the electron gun 9 are supplied to the deflection yoke 8.
After being deflected in a predetermined direction, the light is projected through the shadow mask 6 onto the fluorescent film. A magnet group 1 for purity adjustment and convergence adjustment is provided outside the neck 2.
0 is arranged.

Since the image display operation of the color cathode ray tube according to the above configuration is the same as the image display operation of the known color cathode ray tube, the description of the image display operation of the color cathode ray tube will be omitted.

In the case of a panel having a flat outer surface and a curved inner surface, the difference in thickness between the central portion and the peripheral portion becomes significant. The equivalent radius of curvature in the diagonal direction of the panel outer surface is 10,000
If it is not less than mm, the difference in transmittance between the central part and the peripheral part increases. Therefore, the contrast also differs between the central part and the peripheral part of the screen.

The equivalent radius of curvature RE is defined by the following equation based on the distance E from the center portion of the face plate to the peripheral portion, and the distance (recess dimension) Z between the central portion and the peripheral portion in the tube axis direction.

RE = (Z ² + E ² ) / 2Z In the aspherical panel, the panel thickness difference on the diagonal axis, the long axis, and the short axis can be set independently, and the luminance required in each part of the face plate Set value can be set. In the cathode ray tube of FIG. 1, since the equivalent radius of curvature of the outer surface of the face plate is larger than the equivalent radius of curvature of the inner surface of the face plate, the thickness of the peripheral portion of the face plate is larger than the thickness of the central portion.

In the following embodiments, the effective plane of the screen is 46
cm, a semi-clear panel having a transmittance of 80% was used.

The formulas for defining the outer and inner surfaces of this panel are shown below.

Z ₀ (X, Y) = Rx − [{Rx−Ry + (R
y ² −Y ² ) ^1/2 } ² −X ² ] ^1/2 Z ₀ (X, Y) indicates a drop from the center of the screen at a position (X, Y) from the center of the screen.

The equivalent radius of curvature is as shown in Table 1.

[0030]

[Table 1] Table 1 Equivalent radius of curvature of panel

The thickness at the center of the panel is 11.5 mm,
The plate thickness at a position of 240 mm in the diagonal direction is 25.3 mm.

In the first and second embodiments, the thin film 5 is a single-layer film.

FIG. 2 is a flowchart showing steps for forming a colored film. First, the front of the panel is cleaned to remove dirt attached to the front of the panel. Next, after the panel is dried, the temperature of the panel surface is adjusted to 35 ± 1 ° C. Spin coating of liquid mixture 1 on the front of panel maintained at proper temperature (sp
After that, the panel was heated at 160 ° C. for 40 minutes, and the mixed solution 1 was baked to form a thin film 5. The rotation speed of the panel when applying the mixture is 150 rpm,
The application time is 30 seconds.

Table 2 shows the composition of the mixed solution 1 for forming a colored film. In this example, an organic pigment (hereinafter, simply referred to as a pigment) was used as a pigment, and a pigment liquid was used as a mixed liquid 1.

[0035]

Table 2 Composition of liquid mixture 1 (wt%)

In Table 2, the pigment liquid a is the pigment liquid according to the first embodiment, and the pigment liquid b is the pigment liquid according to the second embodiment.

As the organic pigment, quinacridone red and phthalocyanine blue are used, and the silane coupling agent is γ-
Glycidoxypropyltrimethoxysilane was used.
The organic pigment has a minimum particle size of 30 nm and an average particle size of 50 nm.
It is. As the particle size of the pigment increases, the unevenness of the surface of the pigment film increases, so that the haze increases. Therefore, the particle size of the dye is preferably smaller than the region where Rayleigh scattering occurs. Specifically, the size is preferably 100 nm or less, more preferably 70 nm or less. When the average particle size of the organic pigment is 20 nm or more, the dispersion of the organic pigment in the alcohol solution is favorably maintained by the colloid.

Each pigment solution contains quinacridone red in 0.1%.
15 wt%, 0.05 wt% of phthalocyanine blue,
1.0% by weight of tetraethoxysilane and 8% of ethanol
0 wt%, the balance being pure water.

Comparative liquid c did not use either γ-glycidoxypropyltrimethoxysilane or colloidal silica. Comparative liquid d used 0.5 wt% of γ-glycidoxypropyltrimethoxysilane as a dispersant. On the other hand, the pigment liquid a contains 0.5 of colloidal silica as a dispersant.
wt% was used. The pigment liquid b was prepared by adding 0.5 wt of γ-glycidoxypropyltrimethoxysilane as a dispersant.
% And colloidal silica at 0.5 wt%. The average particle size of the colloidal silica is 30 nm.

FIG. 3 is a diagram showing the relationship between the electrokinetic potential (ζ potential) and the pH in the pigment liquid a and the pigment liquid b. As can be seen from FIG. 3, the pigment liquid b to which the silane coupling agent is added has a smaller change in the ζ potential of the pigment even when the pH is changed, as compared with the pigment liquid a to which the silane coupling agent is not added.
That is, the pigment liquid b to which the silane coupling agent is added is p
The resistance to fluctuation of H (maintaining the dispersed state of the pigment) was improved. Usually, the silicon alkoxide liquid is acidic. When the silane coupling agent is added, the silane coupling agent covers the surface of the colloidal silica or the pigment liquid.
Increase the absolute value of the potential. Therefore, even if silicon alkoxide is added to the pigment liquid, the dispersion is not broken. Therefore,
When colloidal silica (SiO ₂ ), which is a metal oxide, and a silane coupling agent are used in combination, the pigment can be more favorably dispersed.

Each of the liquids shown in Table 2 was applied to the front of the panel and fired to form a thin film. A colored film was formed by controlling the film thickness d to be 200 ± 20 nm.

Table 3 is a table comparing the characteristics of the colored films.

[0043]

Table 3 Comparison of characteristics of colored films

The comparative films g and h correspond to the comparative solutions c and c, respectively.
It is a film manufactured using the comparative liquid d. The pigment film e and the pigment film f are films produced using the pigment liquid a and the pigment liquid b, respectively.

The pigment film e containing colloidal silica was improved in all items in Table 2. The combined use of colloidal silica and a silane coupling agent can further improve all items in Table 3.

First, the absorbance of the comparative film and the pigment film (555)
nm wavelength).

Absorbance of pigment film e (wavelength of 555 nm)
Is 0.034 larger than the comparative film g and 0.027 larger than the comparative film h. Further, the absorbance of the pigment film f (55
(Wavelength of 5 nm) is 0.047 larger than the comparative film g and 0.040 larger than the comparative film h. Since the pigment film e and the pigment film f have a large absorbance, the film thickness can be reduced.
The film strength increases.

Next, the peak absorbance (wavelength of 577 nm) characteristics of the comparative film and the pigment film are compared.

The peak absorbance (wavelength of 577 nm) of the pigment film e is larger by 0.046 than that of the comparative film g,
0.040 larger than. Further, the peak absorbance (wavelength of 577 nm) of the pigment film f was 0.0
61 larger than the comparative film h by 0.055. Since the pigment film e and the pigment film f have a large peak absorbance, the wavelength selective absorption effect of the films is increased, and the contrast is improved. Further, the thickness of the pigment film can be reduced.

FIG. 4 is a characteristic diagram of the amount of colloidal silica added to the pigment liquid and the peak absorbance (absorbance at 577 nm) of the pigment film.

When no colloidal silica was added (comparative film h), the peak absorbance was 0.155%. When the amount of colloidal silica added was 0.5 wt% or more, the peak absorbance was 0.21%, and the absorbance was saturated.

By adding colloidal silica having the same kind of charge as the pigment, the pigment is dispersed by repulsion of the charge. By this action, aggregation of the pigment in the state of the pigment liquid and the pigment film can be reduced. As a result, voids in the pigment film are reduced, and the pigment film becomes closer to a finely packed structure.

The decrease in the voids in the pigment film increases the absorbance per 200 nm of the thickness of the pigment film. Therefore, the thickness of the pigment film can be reduced.

The particle size of the colloidal silica is one of the particle size of the pigment.
A size of up to 1/20 is good. The diameter (particle size) of the colloid particles used in this example is 1 to 100 nm. When the colloid particles enter between the pigment particles, it is possible to prevent the pigments from contacting and aggregating due to the electric repulsion of the colloid particles. By adding colloidal silica to the mixture, the dispersion of the pigment can be maintained for a long time.
That is, since the chargeable substance is added to the pigment liquid, the pigment is well dispersed. Further, since the dispersion of the pigment can be maintained for a long time, the work of stirring the coating liquid can be reduced.

The luminous transmittance of a pigment film that selectively absorbs wavelength must be 85% or less. Luminous transmittance is 85
%, The effect of selectively absorbing wavelength is small,
Cannot improve image contrast. The luminous transmittance of the pigment film e was 82%. The reason for this is that the aggregation of the pigment is reduced and the pigment film has a finely packed structure.

On the other hand, in order to make the luminous transmittance of the film manufactured using the comparative solution c 82%, the film thickness was required to be 380 nm.

Next, the relationship between the surface roughness and the luminous haze of the comparative film and the pigment film will be compared.

The surface roughness of the pigment film e is 11 nm smaller on average than the comparative film g, and 8 μm on average compared to the comparative film h.
nm smaller. The surface roughness of the pigment film f can be reduced by an average of 16 nm as compared with the comparative film g, and can be reduced by an average of 13 nm as compared with the comparative film h. The surface roughness is 10 points average roughness Rz according to JIS (Japanese Industrial Standard) B0601.
Was measured. The evaluation length is about 2.5 mm.

FIG. 5 is a diagram showing the relationship between surface roughness and visual haze. By reducing the luminous haze, blurring of an image can be suppressed and contrast can be improved. The pigment film e and the pigment film f could have a luminous haze of 1.5% or less. The pigment film e and the pigment film f have a surface roughness of 7
0 nm or less could be achieved.

In the prior art, even if a colored film is formed using an organic pigment having an average particle diameter of 50 nm, the organic pigment partially aggregates, so that the particle diameter of the organic pigment increases to about 180 nm. I was Therefore, the surface roughness of the pigment film was large.

Since the surface roughness of the colored film is reduced, the luminous haze of the pigment film e is 2.3% smaller than the comparative film g and 1.6% smaller than the comparative film h. Further, the luminous haze of the pigment film f is 2.5% superior to the comparative film g and 1.8% superior to the comparative film h. Since scattering of light by the colored film is small, blurring of an image can be suppressed, and a clear image can be displayed.

The luminous haze was determined by equation (1).

[0063]

(Equation 1)

Here, Td (λ) is the diffuse transmittance, Ti (λ)
Indicates integrated transmittance, and S (λ) indicates relative luminosity.

In the comparative film g and the comparative film h, since the pigment is agglomerated, the substantial particle size of the pigment is large. Therefore, the unevenness of the surface of the comparative film becomes large, and the visual haze is increased.

On the other hand, since the pigment film e and the pigment film f contain colloidal silica, the surface roughness of the pigment film can be reduced by reducing the particle size of the pigment in the pigment liquid, and the visual haze can be reduced. Can be.

Next, the visual haze after the temperature change test of the comparative film and the pigment film is compared.

In FIG. 1, when the thickness of the thin film 5 is increased, cracks occur in the thin film. The presence of cracks in the thin film reduces the mechanical strength of the thin film. When the thin film is a colored film for improving the contrast, the effect of the contrast of the thin film is reduced.

The luminous haze after the temperature change test was deteriorated by 0.6% in the comparative film g and 0.4% in the comparative film h, respectively, as compared to before the temperature change test. On the other hand, the pigment film e deteriorated by 0.1%, and the pigment film f did not deteriorate. The temperature change test is a test in which a temperature cycle of −50 to 50 ° C. is repeated 10 times every 24 hours.

FIG. 6 is a diagram showing the relationship between the thickness of the pigment film and the luminous haze after repeating the temperature cycle of −50 to 50 ° C. ten times.

The line A is the characteristic of the film produced using the pigment liquid a, and the line B is the film produced using the comparative liquid d. The film thickness was varied from 175 to 400 nm.

The film manufactured using the comparative solution d had a thickness of 1
When the thickness was 75 nm, the haze was 2.5%, and when the thickness was 400 nm, the haze was 6.9%. The change in haze when the film thickness is changed by 255 nm is 4.4%, and the haze after the temperature change test increases as the film thickness increases.

On the other hand, the film produced using the pigment liquid a had a haze of 0.9% when the film thickness was 175 nm and 2.1% when the film thickness was 400 nm. Film thickness 2
The change in haze when changed by 55 nm is 1.2%, and the haze after the temperature change test increases as the film thickness increases, but the rate of change is small. For example, if the film thickness is 30
The haze of the 0 nm film after the temperature change test is 1.5%, which is a sufficiently small value for practical use.

The pigment liquid to which colloidal silica is added has good affinity between colloidal silica and ethoxysilane, so that ethoxysilane easily penetrates into the gaps between the pigment particles. Further, in the pigment film containing colloidal silica, pigment particles are densely overlapped. Therefore, the strength of the pigment film itself is improved, and cracks in the pigment film can be suppressed. Further, silica obtained by hydrolyzing, dehydrating and condensing ethoxysilane, and calcining also improves the adhesive strength between the face plate and the pigment film.

FIG. 7 is a cross-sectional view of the panel surface on which the pigment film has been formed. A single-layer thin film 5 on the surface of the face plate 1F
There is A. The thin film 5A is composed of a pigment 51 made of quinacridone red and phthalocyanine blue, colloidal silica 52 as a dispersant, and silica 53 for filling gaps between the pigment particles and fixing the pigment particles.

In order to obtain a film having practical strength, the film thickness is preferably as small as possible. However, if the thickness of the pigment film is too small, a sufficient wavelength selective absorption effect cannot be obtained. When the concentration of the pigment in the pigment liquid is increased in order to obtain a sufficient wavelength selective absorption effect, the ratio of the pigment 51 to the silica 53 for the binder (pigment / binder) increases, and the strength of the film decreases. For this reason, it is difficult to make the thickness of the pigment film thinner than 80 nm.

When the thickness of the pigment film is more than 300 nm, the strength of the film becomes weak, and irregularities (undulations) having a large period are formed on the film surface, so that the film thickness becomes non-uniform. When the thickness of the pigment film is set to 300 nm or less, distortion of an image caused by non-uniform thickness can be prevented.
That is, the thickness of the pigment film is preferably 80 nm to 300 nm.

The surface resistance of the pigment film is 1 × 10 ¹² Ω / □
This is the description of the insulating film.

Each of the pigment films e and f has a thickness of 200 nm.
In the following, the film has a luminous transmittance of 85%. Therefore,
The pigment films e and f are excellent in contrast and hard.

When a silica film for protecting the pigment film is formed on the pigment film, a thin film stronger than the pigment films e and f can be obtained.

Further, in the present embodiment, the description has been made mainly of SiO ₂ , but instead of colloidal silica, Al ₂ O
_{3, ZrO} 2, TiO ₂ or the like of the metal oxide fine particles (metal colloid) can be suppressed agglomeration of the pigment even.
Al ₂ O ₃ , ZrO ₂ , TiO _{2 and the} like are insulative metal oxide fine particles, but because they are colloids, they adsorb ions and the like present in the solvent on the surface of the colloidal particles and are charged. Here, the dispersoid is a metal or metal oxide colloid. Furthermore, Au (gold), A
g (silver), metal fine particles such as Pd (palladium), and I
Even with conductive metal oxide fine particles such as TO (indium tin oxide), ATO (antimony tin oxide), antimony oxide, tin oxide, and niobium oxide, the aggregation effect of the pigment can be suppressed. As the dispersant, two or more of the above materials may be used in combination.

Even when conductive fine particles such as Au, Ag, Pd, ITO, and ATO are used, the added amount of these fine particles is small, so that the conductive fine particles 52 are dispersed in the colored film as shown in FIG. are doing. Therefore, the surface resistance of the pigment film is 1
× 10 ¹² Ω / □ or more, which is an insulating film.

Materials for wavelength selective absorption include, in addition to the dyes shown in Table 1, quinacridone pigments, dioxazine pigments such as dioxazine violet, phthalocyanine pigments such as phthalocyanine green, acid red, azomethine yellow, metal complex azo. A system pigment (yellow) or the like may be used. Further, an inorganic pigment such as carbon black may be used. These dyes may be used alone or in combination.

Further, other metal alkoxides may be used in place of the tetraethoxysilane (silicon alkoxide) shown in Table 2, but the film to which silicon alkoxide is added has higher strength than the film to which other metal alkoxide is added. Was.

As the dispersion medium, a lower alcohol such as methanol, diacetone alcohol, isopropyl alcohol, ethyl cellosolve (= 2-ethoxyethanol) or the like may be used instead of ethanol in Table 2.

In the third and fourth embodiments, the thin film 5 is a multilayer film.

FIG. 8 is a flowchart showing steps for forming a multilayer film.

First, the front surface of the panel is washed to remove dirt. Next, the panel is dried and the temperature of the panel surface is set to 35 ±
Adjust to 1 ° C. The liquid mixture 1 is spin-coated (spin-coated) on the front surface of the panel maintained at an appropriate temperature, and then the liquid mixture 1 applied on the front surface of the panel is dried to form a first layer.
The rotation speed of the panel when applying the mixed liquid is 150 rpm
m, the application time is 30 seconds. After forming the first layer, the temperature of the panel surface is adjusted to 45 ± 1 ° C. Next, the liquid mixture 2 is spin-coated on the first layer, and then the liquid mixture 2 applied on the front surface of the panel is dried to form a second layer. After forming the second layer, the temperature of the panel surface is adjusted to 45 ± 1 ° C. Thereafter, the mixed solution 3 is spin-coated on the second layer. The rotation speed of the panel when applying the mixed liquid 2 and the mixed liquid 3 is 150 rpm, and the application time is 60 seconds. Mixed liquid 3
Was applied, the panel was heated at 160 ° C. for 30 minutes, and the first layer, the second layer, and the mixed solution 3 were baked to form a multilayer film 50.

As the mixed liquid 1, the same comparative liquid and pigment liquid as those of the first embodiment were used.

Table 4 shows the composition of the mixed solution 2 for forming the conductive layer.

[0091]

Table 4 Composition of liquid for forming conductive film

In the conductive film forming liquid, conductive particles
Silver (Ag) and palladium (Pd) particles are added. The average particle size of silver and palladium is 20 nm.

Table 5 shows mixed solution 3 for forming a silica layer.
The composition of A silicon alkoxide solution was used for the mixed solution 3.

[0094]

Table 5 Composition of silicon alkoxide liquid

The silicon alkoxide solution is obtained by dissolving tetraethoxysilane in ethanol as a solvent and adding nitric acid and water to cause a hydrolysis reaction and a dehydration condensation reaction to form a siloxane bond. After that, firing is performed to form a silica layer.

The thickness of the pigment layer is 200 ± 20 nm, the thickness of the conductive layer is 25 ± 5 nm, and the thickness of the silica layer is 75 ± 5 nm.
And a thin film was prepared.

Table 6 shows a comparison of characteristics between the comparative films k and l formed using the comparative liquids c and d and the multilayer films i and j formed using the pigment liquids a and b. Multilayer film i according to the third embodiment, multilayer film j
Is a fourth embodiment.

[0098]

Table 6 Comparison of characteristics of three-layer films

FIG. 9 is a sectional view showing the structure of a thin film 5B which is a multilayer film according to the present invention.

The thin film 5 formed on the panel glass includes a pigment layer 501, a conductive layer 502, and a protective layer 503.

The pigment layer has the same structure as the pigment film of Example 1. The pigment 51 made of quinacridone red and phthalocyanine blue, the colloidal silica 52 as a dispersant, and the pigment particles are filled by filling gaps between the pigment particles. It is constituted by silica 53 to be fixed.

The second layer is made of gold (Au) and palladium (P
The fine particles of d) are fixed by silica as a binder.

The third layer, which is the protective layer 503, is a silica layer formed by subjecting a silicon alkoxide solution to a hydrolysis reaction and a dehydration condensation reaction.

The thickness d1 of the pigment layer 501 as the first layer is 8
In the case of 0 nm to 300 nm, from the viewpoint of optical characteristics and low resistance, the thickness d2 of the second layer is preferably 15 to 50 nm, and the thickness d3 of the third layer is preferably 50 to 140 nm.

The thickness d2 of the conductive layer 502 is 25 nm. The practical thickness d2 of the conductive layer is 15 to 35 nm.

The multilayer film i and the multilayer film j have a luminous haze of 1.
It is less than 5%.

Since the conductive layer is formed on the pigment layer, the surface roughness is generally smaller than that of the single-layer film. Since the surface roughness of the multilayer film is reduced, the luminous haze of the multilayer film i is 1.7% smaller than the comparative film k and 1.8% smaller than the comparative film h. The luminous haze of the multilayer film j is 2.8% better than that of the comparative film k and 2.9% better than that of the comparative film h. Since the visual haze is small, blurring of the image can be suppressed, and a clear image can be displayed. Preferably, the visual haze is 1.0% or less.

In general, a light-absorbing film has a m-th layer thickness dm and a complex refractive index nm-i × km (m = 1,
2,3 ...). Here, nm is a refractive index, and km is an attenuation coefficient.

The multilayer film is composed of a first layer and a second layer from the panel side.
The layers are stacked in the order of the third layer. The first layer in contact with the panel is a pigment layer that selectively absorbs wavelengths. The second layer formed on the pigment layer is a conductive layer. The third layer formed on the conductive layer is a silica layer for protecting the thin film. A refractive index n1 of the first layer, a refractive index n2 of the second layer,
The refractive index n3 of the third layer has a relationship of n3 <n2 <n1.

In particular, the present inventors have determined that the three-layer structure of the pigment layer, the conductive layer, and the low-refractive-index layer regulates the refractive indices of the first layer and the second layer so that both the contrast function and the low-reflection layer are obtained. Was successfully realized.

FIG. 10 shows the difference in the refractive index between the first layer and the second layer.
It is a figure which shows the relationship with luminous reflectance. Line 11 has a first pigment layer thickness d1 of 100 nm, line 12 has a pigment layer thickness d1 of 150 nm, and line 13 has a pigment layer thickness d1 of 200 nm.
The nm and line 14 represent the luminous reflectance when the thickness d1 of the pigment layer is 300 nm. The thickness d2 of the second layer is 25 n
m, and the thickness d3 of the third layer is 75 nm. The complex refractive index of the conductive layer is 1.47-0.43i at 555 nm.

To reduce the luminous reflectance, n1-n2
(Difference between refractive index n1 of first layer and refractive index n2 of second layer)>
It may be set to 0. Further, the value of n1-n2 is set to 0.1 to 0.
By selecting from the range of 6, the lowest luminous reflectance at each film thickness can be obtained.

Further, for example, an IT having a high refractive index is formed in the second layer.
When O is used, fine particles of a substance having a higher refractive index than ITO are dispersed in the colored film as the first layer, and the difference between the refractive index of the colored layer and the refractive index of the conductive layer is set to 0.1 to 0.6. The luminous reflectance can be reduced by controlling to within the range. That is, by dispersing a substance having a higher refractive index than the substance forming the conductive layer in the pigment layer, the luminous reflectance can be reduced. According to the present invention, it is possible to make the refractive index of the coloring layer larger than that of the conductive layer.

Further, the refractive index of the colored layer can be easily adjusted by adjusting the content of the high refractive index fine particles contained in the pigment layer. In particular, the pigment layer contains colloidal silica for improving the dispersion of the pigment and conductive fine particles such as ATO fine particles or ITO fine particles for increasing the refractive index.
The wavelength can be selectively absorbed and the luminous reflectance can be reduced.

FIG. 11 is a diagram showing the relationship between the reflectance from the inner surface and the wavelength. The internal reflectivity of a two-layer film in which a protective film (silica film) was formed on the pigment film f and a three-layer film as the multilayer film j were compared. Between 400 nm and 800 nm, the reflectivity from the inner surface of the two-layer film changes between 4% and 6%.
The highest curve is drawn at 50 nm. On the other hand, the reflectance from the inner surface of the three-layer film varies between 2 and 2.5%. That is, in the visible light region, the three-layer film of the present embodiment can suppress the reflection from the inner surface more than the two-layer film. The above-mentioned reflectance is the reflectance at the time of regular reflection. In addition, the reflectance was measured by irradiating light at an angle of 5 degrees from a line perpendicular to the sample surface and detecting the light at a position 5 degrees away from the perpendicular line.

The surface resistance of the multilayer film i was 820 Ω / □ and the surface resistance of the multilayer film j was 600 Ω / □, and all the films could be made smaller than the surface resistances of the comparative films k and l. Further, since the surface resistance is sufficiently small, it is possible to reduce the electromagnetic wave leaking to the front side of the panel of the cathode ray tube.

Since the surface roughness (irregularity) of the pigment layer of the multilayer film i is smaller than that of the comparative film k and the comparative film 1, cutting of the conductive path of the conductive layer can be prevented. Therefore, the multilayer film i can have a lower surface resistance than the comparative films k and l. Since the multilayer film j has less irregularities in the pigment layer than the multilayer film i, a conductive layer having a more uniform thickness than the multilayer film i can be formed. Therefore, the multilayer film j can have a lower surface resistance than the multilayer film i.

Although the average particle diameter of the conductive fine particles of the above-described embodiment is 20 nm, the average particle diameter of the conductive fine particles may be practically 2 to 35 nm. Also, as conductive fine particles,
In addition to noble metal fine particles such as gold (Au), silver (Ag), and palladium (Pd), conductive metal oxide fine particles such as I
TO or ATO may be used. Further, since the conductive layer is formed by fixing conductive fine particles, even if the surface of the lower pigment layer is rough, the roughness of the upper surface of the conductive layer can be made smaller than the surface roughness of the pigment layer. .

The strength of the thin film was evaluated according to the pencil hardness test of JIS K5400.

The strength of the multilayer film i is 7H and the strength of the multilayer film j is 9H, which is stronger than the comparative films k and l.

The film thickness in the above example was measured at ten locations, and the average value was taken.

The conductive layer and the protective layer may be formed by vapor deposition. In this case, the conductive layer and the protective layer are greatly affected by the unevenness of the pigment layer.

The protective layer may use magnesium fluoride (MgF) or calcium fluoride (CaF).

To further improve the contrast of the image, a colored panel glass may be used.

FIG. 12 is a partial sectional view of a panel portion of a flat cathode ray tube.

The panel of FIG. 12 is the same as the panel of FIG.

The panel 1 has a thin film 17 formed on the outer surface of the screen. In the thin film 17, the plate thickness Tc at the center of the screen is smaller than the plate thickness Td at the periphery of the screen (Tc <Td).

The film thickness Fc of the thin film 17 at the center of the screen is larger than the film thickness Fd of the thin film 17 at the periphery of the screen (F
c> Fd). That is, the film thickness of the thin film 17 is different between the central part of the screen and the peripheral part of the screen. With the configuration of the thin film 17 shown in FIG. 12, it is possible to correct a difference in contrast due to a difference in panel thickness between a central portion of the screen and a peripheral portion of the screen.

FIG. 13 is a diagram for explaining the distribution of the thickness of the thin film 17 and shows contour lines of the thin film 17. The contour lines of the thin film 17 have an elliptical shape having a major axis in the X-axis direction and a minor axis in the Y-axis direction. Note that the thin film 17 may be formed so that the contour lines are concentric or vertically long elliptical.

FIG. 14 is a diagram showing a change in the thickness of the thin film 17. The thin film 17 is thickest at the center of the screen and thinner at the periphery of the screen. By forming in this way, it is possible to improve the difference in transmittance and the difference in contrast between the central part of the screen and the peripheral part of the screen.

By making the screen flat, the visibility of the image can be improved. Further, the contrast when using a panel having a high transmittance can be improved.

FIG. 15 is a diagram showing a change in the thickness of the thin film 17 formed on the cathode ray tube in which the thickness of the panel at the center of the screen is larger than the thickness of the panel at the periphery of the screen. In a cathode ray tube in which the thickness of the panel at the center of the screen is larger than the thickness of the panel at the periphery of the screen, for example, the cathode ray tube described in JP-A-11-238481, the film thickness at the center of the screen is greater than the thickness at the periphery of the screen. By forming a thin thin film, the difference in contrast between the center of the screen and the periphery of the screen can be improved.

In the above embodiment, a cathode ray tube was used as an image display device, but an ELD (Electro-Luminescen) was used.
t Display), PDP (Plasma Display Panel), liquid crystal display (Liquid Crystal Display), VFD (Vacuum
Fluorescent Display), FED (Field Emission Dis
play).

[0134]

According to the above construction, the dispersion of the pigment in the coating solution can be maintained for a long time. Further, the present invention can provide a thin colored film. Further, the present invention can provide a thin film capable of improving the absorbance of the colored film and suppressing light scattering by the colored film.

[Brief description of the drawings]

FIG. 1 is a sectional view of a cathode ray tube according to the present invention.

FIG. 2 is a flowchart for forming a colored film.

FIG. 3 is a diagram showing the relationship between the ζ potential and the pH of a pigment liquid a and a pigment liquid b.

FIG. 4 is a characteristic diagram of the amount of colloidal silica added to a pigment liquid and the peak absorbance of a pigment film.

FIG. 5 is a diagram showing a relationship between surface roughness and visual haze.

FIG. 6 is a graph showing the relationship between the thickness of a pigment film and the luminous haze after a cycle of −50 to 50 ° C. is repeated 10 times every 24 hours.

FIG. 7 is a sectional view of a pigment film.

FIG. 8 is a flowchart showing a process for forming a multilayer film.

FIG. 9 is a cross-sectional view illustrating a configuration of a multilayer film.

FIG. 10 is a diagram illustrating a relationship between a difference in refractive index between a first layer and a second layer and a luminous reflectance.

FIG. 11 is a partial cross-sectional view of a panel portion of a cathode ray tube on which a thin film is formed.

FIG. 12 is a diagram illustrating the distribution of the thickness of a thin film.

FIG. 13 is a diagram showing a change in thickness of a thin film.

FIG. 14 is a diagram showing a change in the thickness of a thin film.

FIG. 15 is a diagram showing a change in thickness of a thin film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Panel part 2 Neck part 3 Funnel part 4 Screen 5, 5A, 5B Thin film 501 Pigment layer 502 Conductive layer 503 Protective layer 51 Pigment 52 Colloidal silica 53 Silica

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masahiro Nishizawa 3300 Hayano, Mobara-shi, Chiba Prefecture Within Hitachi, Ltd. Display Group (72) Inventor Noriharu Uchiyama 3300, Hayano, Mobara-shi, Chiba Prefecture Hitachi, Ltd. Display Group, Inc. (72) Inventor Toshio Tojo 3681 Hayano, Mobara-shi, Chiba F-term in Hitachi Device Engineering Co., Ltd. 5C032 AA02 DD02 DE01 DE03 DG01 DG02 DG04

Claims (11)

[Claims] 1. A cathode ray tube comprising: a panel section having a plurality of fluorescent films formed on an inner surface thereof; a neck section containing an electron gun; and a funnel section connecting the panel section and the neck section. Pigment and SiO ₂ , Al ₂ O ₃ , Zr on the front
A cathode ray tube having a film containing at least one kind of fine particles of O ₂ and TiO ₂ . 2. The cathode ray tube according to claim 1, wherein the outer surface of said panel has an equivalent radius of curvature in a diagonal direction of 10,000 mm or more. 3. The cathode ray tube according to claim 1, wherein the luminous transmittance of the film is 85% or less. 4. A cathode ray tube comprising: a panel section having a plurality of fluorescent films formed on an inner surface thereof; a neck section containing an electron gun; and a funnel section connecting the panel section and the neck section. A thin film on the front side, said thin film comprising pigment and Si
A cathode ray tube comprising a coloring layer containing at least one kind of fine particles of O ₂ , Al ₂ O ₃ , ZrO ₂ , and TiO ₂ , a conductive layer, and a protective layer. 5. The thin film according to claim 4, wherein the pigment layer has a thickness of 80 to 300 nm, and the conductive layer has a thickness of 15 to 50 nm.
A cathode ray tube, wherein the thickness of the protective layer is 50 to 140 nm. 6. The cathode ray tube according to claim 5, wherein the luminous haze of the thin film is 1.5% or less. 7. The cathode ray tube according to claim 5, wherein said protective layer is a silica layer. 8. The cathode ray tube according to claim 5, wherein the outer surface of the panel has an equivalent radius of curvature in a diagonal direction of 10,000 mm or more. 9. A cathode ray tube according to claim 8, wherein the thin film has a larger thickness at the center of the screen than at the periphery of the screen. 10. A cathode ray tube comprising: a panel for displaying an image; a neck containing an electron gun; and a funnel connecting the panel and the neck. A pigment film containing fine particles of noble metal or metal oxide, wherein the film has a sheet resistance of 10
A cathode ray tube having a resistance of ¹² Ω / □ or more. 11. The method according to claim 10, wherein the fine particles are A
u, Ag, Pd, Al ₂ O ₃ , ZrO ₂ , ITO, AT
A cathode ray tube comprising at least one of O, antimony oxide, tin oxide and niobium oxide.