JP2702821B2 - CRT with low reflection film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube having a low reflection film having a low reflection film formed on a face plate.

[0002]

2. Description of the Related Art Recently, the demand for the image quality of a color television receiver has been greatly increased, and therefore, a significant improvement in the contrast performance of a cathode ray tube is desired.

Next, the contrast performance will be described with reference to FIG. FIG. 8 is an enlarged schematic cross-sectional view of a fluorescent screen portion of the cathode ray tube. In FIG. 8, an inner surface of the face plate 2 has black light absorption for reducing the external light reflectance of the fluorescent screen and improving the contrast performance. Membrane 6 and BGR
A (blue / green / red) three-color phosphor layer 4 and a metal back film 5 are formed.

In the cathode ray tube having the above structure, the light emission luminance of the phosphor screen is F ₀ , the output luminance of light passing through the face plate 2 is F ₁ , and the light transmittance of the face plate 2 is Tp. , The reflectance of the fluorescent film in which all of the BGR three-color phosphor layer 4, the black light absorbing film 6, and the metal back film 5 are integrated is Rp, the aperture ratio of the black light absorbing film 6 is Tb, and the incident light entering the fluorescent screen. Is E ₀ , the intensity of the external light reflected on the outer surface of the face plate 2 is E ₁ , and the intensity of the external light reflected on the inner surface of the face plate 2 and the outside of the face plate 2 is reflected by the fluorescent film. Assuming that the intensity of the reflected external light from the phosphor screen is E ₂ , the contrast index Ct can be expressed by the following equation 1.

[0005]

(Equation 1)

In Equation 1, since the material of the face plate 2 is glass, the surface reflection at the interface with air and vacuum is estimated to be 4%. It is clear from Eq. 1 that E ₁ is more constant, and therefore, in order to improve the contrast performance, that is, the contrast index Ct, F ₁ , that is, the output luminance must be increased,
E ₂ , that is, the intensity of the light reflected off the phosphor screen may be reduced. The E _{to 2} to small, it can be seen that it is effective to reduce the higher light transmittance Tp of the face plate 2 of Equation 1. For this reason, as a method of improving the contrast performance of the cathode ray tube, the light transmittance Tp of the face plate 2 is often reduced.
In this case, as disadvantages, it is more apparent in Equation 1 drops simultaneously output luminance F ₁ of the cathode ray tube.

FIG. 10 is a view for explaining the optical characteristics of the face plate 2 and the phosphor screen. In the figure, BGR indicates the relative emission intensity spectrum distribution of the light emitted from the BGR three-color phosphor layer 4. The curves (II) and (II)
(I), (IV) and (V) indicate that the glass thickness of the face plate 2 is 1
The spectral transmittance distribution of the face plate 2 in the case of 3 mm is shown. (II) shows that the spectral transmittance in the visible light region is about 85%.
(III) is a gray type with a spectral transmittance of about 69% in the visible light region, (IV) is a tint type with a spectral transmittance of about 50% in the visible light region, and (V) is a visible type. It shows a dark tint type spectral transmittance of about 38% in the optical region.

The lower the spectral transmittance of the face plate 2 is, the more disadvantageous the luminance performance of the fluorescent screen of the cathode ray tube is, which is apparent from the relationship with the relative emission intensity spectrum distribution of the fluorescent screen of the BGR. Since the external light incident on the fluorescent screen of the cathode ray tube can be effectively removed, it is advantageous in terms of contrast, and in addition to the recent tendency to emphasize the image quality of color television receivers, the conventional clear type and gray, which emphasize luminance performance. A tint type and a dark tint type face plate 2 which emphasize contrast performance more than the type are increasingly used.

Further, with the recent enlargement of the cathode ray tube and the improvement of the luminance performance and the focus performance, the voltage applied to the phosphor screen of the cathode ray tube, that is, the acceleration voltage of the electron beam has been increased, and the color television has been increased. The charge-up phenomenon of the face portion of the receiver has become a serious problem. That is, due to the charge-up phenomenon, fine dust in the air adheres to the face portion, and contaminants and the like become conspicuous, and as a result, the luminance performance of the cathode ray tube is deteriorated. Further, when the viewer approaches the charged face portion, a discharge phenomenon occurs, which may cause inconvenience to the viewer.

For the purpose of preventing the face portion of such a color television receiver from being charged and further improving the contrast performance of an image, as shown in FIG. The cathode ray tube 1 with the antistatic light selective absorption film provided with the light selective absorption film 3 has come to be used. The antistatic selective absorption film 3 is made of a silica (SiO ₂ ) film and has both an antistatic function and a light selective absorption function. In order to form such an antistatic light selective absorption film 3,
Generally, an alcohol solution of silicon (Si) alkoxide having a —OH group or —OR group as a functional group is used as a base paint, and tin oxide (SnO ₂ ) or indium oxide (In ₂ O ₃ ) is used as a conductive filler in the base paint. Are dispersed and mixed, and a coating liquid in which an organic or inorganic dye or pigment is dispersed and mixed is applied and formed on the outer surface of the face plate 2 of the cathode ray tube. After film formation, 100-200
The film is baked at a temperature of ° C.

FIG. 9 is an enlarged schematic sectional view of the antistatic light selective absorption film 3 formed on the outer surface of the face plate 2, wherein an organic or inorganic dye or It has a structure in which pigment particles 8 and conductive filler particles 9 are dispersed.

[0012] Figure 12 is a graph showing a change in surface potential of the face plate of the cathode ray tube, in the figure, L, L ₁
Whereas a change curve of the surface potential at the time of power ON of the cathode ray tube not having the antistatic function (L) and when the power OFF (L _1), the curve M, M ₁ is equipped with an antistatic function is the change curve of the surface potential at the time of the cathode ray tube of power oN (M) and when the power OFF (M _1), a cathode ray tube which comprises an antistatic function, electrically conductive outer surface of the face plate 2 It can be seen that since the conductive film is bonded to the ground, the surface charge steadily escapes toward the ground, and the charge-up is greatly reduced.

The principle of the improvement of the contrast performance by the antistatic light selective absorption film 3 is shown in FIG.
This will be described with reference to an enlarged conceptual sectional view of FIG. The drawing is exactly the same as the sectional view of FIG. 8 except that an antistatic light selective absorption film 3 is added to the outer surface of the face plate 2. In addition, since the glass material of the face plate 2 and the optical refraction index of the antistatic light selective absorption film 3 are selected to be substantially the same, light reflection at the interface between them is almost negligible.
In this case, the contrast index C't can be expressed by the following equation 2 as described above.

[0014]

(Equation 2)

In the case where E ₁ is constant and Tp is also constant in the above equation (2), in order to further improve the contrast index C′t, the light transmittance of the above-mentioned equation (2) and the more antistatic light selective absorption film 3 are required. It is effective to reduce Tc. In the case of the antistatic light selective absorption film 3, by optimizing the spectral transmittance distribution in the visible light region of this film and the relative emission intensity spectrum distribution of light emitted from the BGR three-color phosphor layer 4, It is possible to improve the contrast index C′t while minimizing the decrease in the output luminance F ′ ₁ shown in FIG.

A curve (I) in FIG. 10 shows an example of a spectral transmittance distribution of the antistatic light selective absorption film 3 provided on the outer surface of the face plate 2 of the cathode ray tube for the above purpose. In the figure, if the absorption peak (A) of the antistatic light selective absorption film 3 is located at a portion near the main spectral wavelength in the main spectral wavelengths of 535 nm to 625 nm of the relative emission intensity spectrum distribution of GR, Since the luminance performance of the phosphor screen is disadvantageous, the absorption peak (A) of the absorption band is usually set in the range of 570 nm to 610 nm in consideration of the half width of the absorption band.

Since the light having the wavelength in this range coincides with the region where the visibility of the human eye is relatively high, the light in this region out of the external light (usually white light) component is absorbed and removed. ,
It is preferable in terms of contrast performance. That is, the optical characteristics of the antistatic light selective absorption film 3 of the cathode ray tube 1 with the antistatic light selective absorption film are relatively high as the visibility of human eyes,
In addition, the light emission from the phosphor screen has as little influence as possible.
The absorption band peak (A) is set in the range of 0 to 610 nm to maintain the luminance performance of the phosphor screen while effectively absorbing external light to improve the contrast performance.

It is very important to select an organic or inorganic dye or pigment having such optical characteristics. In the case of the curve (I), an example in which an absorption peak (A) of an absorption band is provided at 580 nm. Show. In such a cathode ray tube 1 with an antistatic light selective absorption film, the organic and inorganic dyes and pigments mixed in the base coating material have relatively broad optical light absorption characteristics, so that the light emission of the fluorescent screen For example, in the case of green (G) light emission, the tail portion on the long wavelength side of the main spectral wavelength, and in the case of red (R) light emission, the sub-peak portion on the short wavelength side of the main spectral wavelength is absorbed by this light selective absorption film. The emission color tone can be improved at the same time.

FIG. 6 shows the surface reflection outside the face plate 2 when an external light (E ₀ ) having an intensity of 100 is incident on the outside surface of the face plate 2 of various kinds of cathode ray tubes. The light intensity (E ₁ ) is reflected by the inner surface of the face plate 2 and the fluorescent film, and the face plate 2
The intensity (E ₂ ) of the external light reflected from the phosphor screen and the ratio of the external light reflected from the surface to the total external light “[E ₁ / (E ₁
+ E ₂ )] × 100 ”.

As for the intensity of the external light reflected from the surface, (E ₁ ), (k) to (n) are reflections on the outer surface of the face plate 2 made of a glass material, and (o) and (p) Is the reflection on the outer surface of the antistatic light selective absorption film 3 having substantially the same optical refractive index as that of the glass material, and the intensity thereof is about 4.0 in all cases. Intensity of reflected light outside the phosphor screen (E
₂ ) depends on the light transmittance of the face plate 2 and the antistatic light selective absorption film 3 formed on the outer surface thereof, and when these light transmittances decrease, the light transmittance sharply decreases. In addition, an incandescent lamp having a relative light emission intensity spectrum distribution as shown in FIG. 13 was used as external light when performing these measurements and evaluations.

It is clear from the respective numerical values (k) to (n) that when the light transmittance of the face plate 2 is relatively high as in (k) and (l), E ₁ "that is, E ₂ is very high compared to [E ₁ / (E ₁ +
E _2)] × smaller value of 100 ", the influence of E ₁ is negligible, as in (m) and (n), the light transmittance of the face plate 2 becomes low, and E ₁ E ₂ is getting very close, impact of E ₁ can not be ignored. As shown in (o) and (p), when a light absorbing film is formed on the outer surface of the face plate 2 which originally has a low light transmittance, this tendency becomes more remarkable.

In terms of phenomena, in order to improve the contrast performance of the cathode ray tube, the lower the light transmittance of the face plate 2 is, the more the light transmittance on the outer surface of the face plate 2 becomes. As the light transmittance is lowered by providing an absorbing film, the reflection of light outside the surface of the face plate 2 becomes more conspicuous, and, for example, the face of a viewer reflected on the face portion of the cathode ray tube becomes clearly visible. It is very annoying to the viewer, and keeping watching the image for a long time may cause eyestrain. This problem of out-of-surface light reflection is particularly noticeable when the light transmittance of the face plate 2 is 50% or less, and the antistatic light selective absorption film 3 is formed on the outer surface of the face plate 2.
And the like, the problem becomes more serious.

[0023]

As described above, in the conventional cathode ray tube, as the light transmittance of the face plate 2 is reduced in order to improve the contrast performance, the face plate is further reduced. As the light transmittance is lowered by providing a light absorbing film on the outer surface of the face plate 2, the reflection of light outside the surface of the face plate 2 becomes more conspicuous, and the reflection makes the viewer harder to see the image. In addition, there are inconveniences such as eye strain on the viewer.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and in order to improve the contrast performance of a cathode ray tube, the light transmittance of a face plate is reduced, and the outer surface of the face plate is further reduced. It is an object of the present invention to provide a low-reflection film-coated cathode ray tube which is less affected by external light even if a light absorbing film is provided.

[0025]

In order to achieve the above object, according to the first aspect of the present invention, silicon (S) is added to the face plate of a cathode ray tube having a light transmittance of 50% or less.
a cathode ray tube with a low-reflection film having a low-reflection film comprising a multilayer optical interference film formed by alternately laminating two or more and four or less high-refractive-index layers and low-refractive-index layers based on the alkoxide of i). The low refractive index layer has a functional group of -O
H group, alkoxy key sheet <br/> de alcoholic solution or ultra-fine particles of magnesium fluoride average particle size below 1000Å to the alcohol solution of silicon (Si) having a -OR group (M
gF ₂₎ is formed by coating with a low refractive index base paint by dispersing mixing, the high refractive index layer, -OH group as a functional group,
Ultrafine tantalum oxide (Ta ₂ O ₅ ) and ultrafine titanium oxide having an average particle size of 1000 ° or less with respect to an alcohol solution of silicon (Si) alkoxide having an —OR group
(TiO ₂ ), ultrafine zirconium oxide (ZrO ₂ )
Alternatively, it is characterized by being formed by a coating film of a high-refractive-index base paint obtained by dispersing and mixing any one of ultrafine zinc sulfide (ZnS) or a mixture thereof.

According to the second aspect of the present invention, when alternately laminating the coating films to be the high refractive index layer and the low refractive index layer according to the first aspect of the present invention, after forming a coating film of a certain layer, the following film is formed on the film surface. It is characterized in that the underlying coating film is cured before forming the coating film.

According to a third aspect of the present invention, in each of the first and second aspects, each coating film is formed by a spin coating method.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, an organic or inorganic dye or pigment is dispersed and mixed in the base paint for forming each coating film. Features.

According to the fifth aspect of the present invention, the first to fourth aspects are provided.
The invention according to any one of the above, wherein conductive fine particles such as tin oxide (SnO ₂ ) or indium oxide (In ₂ O ₃ ) are dispersed and mixed as conductive fillers in each base paint.

Further, the invention of claim 6 is characterized in that, in the invention of claim 5, a conductive filler is dispersed and mixed only in the high refractive index base paint.

[0031]

According to the present invention, the alkoxide of silicon (Si) provided on the outer surface of the face plate even when a face plate having a light transmittance of 50% or less is used. 2 or more layers based on 4
The low-reflection film consisting of a multilayer optical interference film composed of a combination of a high-refractive-index layer and a low-refractive-index layer of the number of layers or less reduces the reflection of external light on the outer surface of the face plate, and reduces the effects of reflection from external light. It can be reduced efficiently and inexpensively.

According to the second aspect of the present invention, after the coating of a certain layer is cured to some extent by curing ,
Since the coating liquid for forming the layer can be applied , there is an effect that the dissolution phenomenon from the underlying layer does not occur.

According to the third aspect of the present invention, since each coating film is formed by the spin coating method, there is an effect that a coating film having a constant film thickness can be formed.

According to the fourth aspect of the present invention, by dispersing and mixing a dye or pigment of an organic or inorganic base paint, high and low refractive index layer is colored, contrast
In addition to the improvement, since the optical absorption characteristics of these dyes and pigments are relatively broad, of the phosphor screen emission, for example, green (G) emission, the tail on the long wavelength side of the main spectral wavelength In the case of red (R) light emission, the sub-peak portion on the short wavelength side of the main spectral wavelength is absorbed by the light selective absorption film, and the emission color tone can be improved at the same time.

According to the fifth aspect of the present invention, by dispersing and mixing conductive fine particles such as tin oxide or indium oxide as a conductive filler in the base paint, an antistatic function is provided and the refractive index is increased. In particular, as in the invention according to claim 6, the refractive index of the high refractive index layer is increased by dispersing and mixing only in the high refractive index base paint, and the refractive index of the low refractive index layer is relatively increased. Can be reduced, and as a result, as a whole, the optical characteristics of the low reflection film are greatly improved.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is an enlarged conceptual sectional view of a face plate portion of a cathode ray tube with a low reflection film according to the present invention. Face ・
On the outer surface of the plate 2, a low-reflection film 12 composed of a combination of two layers of a low-refractive-index layer 11 having the same thickness (d' ₂ ) as the high-refractive-index layer 10 of the constant film layer (d' ₁ ) is formed. Have been.
Conventionally, such a low-reflection film 12 is formed as a high-refractive-index layer 10 by using a high-refractive material such as titanium oxide (TiO ₂ ) to a constant thickness by a vacuum deposition method or the like. Similarly, as the low refractive index layer 11, a low refractive material such as magnesium fluoride (MgF ₂ ) is formed in a constant thickness by a vacuum deposition method or the like. Such a low-reflection film formed by a vacuum deposition method or the like can provide a very good optical performance. However, the processing cost is very high, such as a vacuum deposition method, although for special applications such as a display monitor tube has been introduced already part, introduction into applications such as people live color television receiver Some are very difficult in terms of cost.

In this regard, in the case of the present invention, since each of the high and low refractive index layers is formed by applying a coating liquid based on silicon (Si) alkoxide to the face plate, it is formed.
Mass production can be performed at a very low cost.

Hereinafter, the low-reflection film 12 composed of a combination of a high-refractive-index layer and a low-refractive-index layer shown in FIG. 2 will be specifically described. First, after the outer surface of the face plate 2 is sufficiently cleaned, a conductive filler for antistatic and a dye for coloring are added to an alcohol solution of silicon (Si) alkoxide used for forming the conventional antistatic light selective absorption film. Alternatively, in order to further increase the refractive index of the coating film, a predetermined amount of ultrafine titanium oxide (TiO ₂ ) having an average particle diameter of 400 ° is mixed with the coating liquid in which the pigment is dispersed and mixed, and a high refractive index coating liquid is mixed. A high-refractive-index layer 10 was formed by applying a film having a constant thickness (d ′ ₁ ) on the outer surface of the face plate 2 by spin coating in the same manner as in the prior art.

The high-refractive-index layer 10 includes organic or inorganic dye or pigment particles 8 in a porous silica film 7 as shown in an enlarged schematic sectional view of the face plate portion in FIG.
And ultrafine titanium oxide (TiO ₂ ) 13 are dispersed in addition to the conductive filler particles 9 and the conductive filler particles 9. When ultrafine titanium oxide (TiO ₂ ) 13 is not added, the refractive index of this film is 1.50 to 1.54, which is almost the same as the refractive index of the glass material of the underlying face plate 2. Since titanium (TiO ₂ ) is a high refractive index material having a refractive index of about 2.35, a certain amount of ultrafine titanium oxide (TiO ₂ )
₂ ) By adding 13, the refractive index of the film can be increased to about 1.8, and the high refractive index layer 10 is formed. Other high refractive index materials that can be used for such purposes include ultrafine tantalum oxide (Ta ₂ O ₅ ), zirconium oxide (ZrO ₂ ), zinc sulfide (ZnS), and the like, and mixtures thereof. The average particle size of these ultrafine particles is preferably 1000 ° or less, more preferably 300 ° or less, from the viewpoint of effectively increasing the refractive index and the uniformity of the formed film.

The high refractive index layer 10 thus coated and formed is cured by a heating furnace.
This is because even if a low-refractive-index coating solution is applied to cure the coating film to some extent and form the low-refractive-index layer 11 on the high-refractive-index layer 10, the elution phenomenon from the underlying high-refractive-index layer 10 does not occur. That's why. In this case, the curing was performed at a temperature of 80 ° C. for 20 minutes. As this curing, it is possible to use not only heating but also ultraviolet rays and chemicals.

Next, a coating liquid obtained by dispersing and mixing a conductive filler for antistatic and a coloring dye or pigment in an alcohol solution of alkoxide of silicon (Si) on the high refractive index layer 10 after curing is completed. On the other hand, in order to further lower the refractive index of the coating film, a fixed amount of ultrafine magnesium fluoride (MgF ₂ ) having an average particle diameter of 300 ° is mixed to form a low refractive index coating solution, and the high refractive index layer 10 is formed. In the same manner as described above, a low-refractive-index layer 11 was formed by applying a film on the high-refractive-index layer 10 with a constant film thickness (d ′ ₂ ) by spin coating.

The low refractive index layer 11 has organic or inorganic dye or pigment particles 8 in the porous silica film 7 as shown in the enlarged schematic sectional view of the face plate portion in FIG.
And ultra-fine magnesium fluoride (MgF ₂ ) 14 are dispersed in addition to the conductive filler particles 9 and the conductive filler particles 9. In a state without addition of ultrafine particles of magnesium fluoride (MgF ₂₎ 14, but this refractive index of the film is from 1.50 to 1.54, magnesium fluoride (MgF ₂₎ itself is a refractive index of about 1.38 Since it is a low refractive index material, the refractive index of the film can be reduced to about 1.42 by adding a certain amount of ultrafine magnesium fluoride (MgF ₂ ) to this film, and the low refractive index layer 11 is formed. You.

The average particle size of the ultra-fine magnesium fluoride (MgF ₂ ) used for such a purpose is 1000Å.
Below, preferably 300 ° or less is desirable from the viewpoint of effectively lowering the refractive index and the uniformity of the formed film.

The low-reflection film 12 composed of the high-refractive-index layer 10 and the low-refractive-index layer 11 formed on the face plate 2 in a constant thickness in this manner is heated to, for example, 175 ° C. by a heating furnace. At a temperature of 30 minutes for baking the film. This baking process is performed for stabilizing the optical characteristics of the film and improving the film strength.

As the film configuration of the low reflection film composed of the multilayer optical interference film, a low refractive index layer having an optical thickness of approximately １ ／ wavelength is L, and a high refractive index layer having an optical thickness of approximately ４ wavelength is used. It is well known that (S) -HL and (S) -2HL are basic in the case of two layers in which the refractive index layer is H and the glass substrate is (S). In the case of a three- to four-layer structure, the combination is slightly complicated, but basically a combination of the detailed description H and L.

The film configuration shown in FIG. 2 is (S) -HL
In the case of ( ₁ ), the respective film thicknesses d ′ ₁ and d ′ ₂ are optimized. FIG. 1A shows the surface spectral reflectance when the conventional antistatic light selective absorption film is formed on the face plate of the cathode ray tube as it is or on the outer surface thereof, and shows a value of about 4% in the visible light region. . FIG. 1B shows the surface spectral reflectance of the anti-static light selective absorption type low reflection film (two layers) in the case of the first embodiment, which is reduced to 1.2% in the visible light region average. .

(M ') to (p') of FIG. 6 show the intensity of the reflected light (E ₁ , E ₂ ) when the low reflection film according to the first embodiment is provided on the outer surface of the face plate 2 of the cathode ray tube. ) And the ratio of surface reflection “[E ₁ / (E ₁ + E ₂ )] × 100” are shown in the same manner as in the prior art, and the (m) 〜
Compared with (p), the ratio of external light reflected from the surface is reduced to about 40% of that in the conventional case, and it can be seen that significant improvement has been made.

Embodiment 2 FIG. 3 shows a face structure of a cathode ray tube with a low reflection film according to the present invention, showing a film configuration of a low reflection film 12 formed by combining four layers of a high refractive index layer 10 and a low refractive index layer 11. It is an expanded sectional conceptual diagram of a plate part. The outer surface of the face plate 2, a constant thickness _{(d "1), (d} " also constant thickness between the high refractive index layer 10 of _{3) (d "2),} (d" low index ₄₎ A low reflection film 12 composed of a combination of four layers 11 is formed.
These coatings are formed using the same materials and processes as those described in Example 1.

FIG. 1C shows the surface spectral reflectance of the antistatic light selective absorption type low-reflection film (four layers) in the case of the second embodiment, which is up to 0.5% in the visible light region average. descend. It can be said that the four-layer product is much superior to the two-layer product in that the surface spectral reflectance is greatly reduced in the entire visible light region. (M ") to (p") of FIG.
The intensity (E ₁ , E ₂ ) of reflected light and the ratio of surface reflection “[E ₁ / (E ₁ + E ₂ )] × 100” when the low reflection film according to the second embodiment is provided on the outer surface of the plate 2. "the is indicative a conventional manner in the case of the conventional same conditions (m) ~
Compared with (p), the ratio of surface reflected extraneous light is reduced to about 17% of the conventional case, which is a great improvement as compared with the first embodiment.

Embodiment 3 FIG. 4 shows an improved low reflectivity 12 film configuration formed by combining two layers of a high refractive index layer 10 and a low refractive index layer 11 as in the case of the first embodiment. FIG. 4 is an enlarged conceptual sectional view of a face plate portion of a cathode ray tube with a low reflection film according to the present invention. The outer surface of the face plate 2 has a constant thickness (d
A low refractive index layer 11 having a constant thickness (d ₂ ) is formed in the same manner as the high refractive index layer 10 of ₁ ). In this case, unlike the first embodiment, the conductive filler particles 9 are dispersed and mixed only in the high refractive index layer 10, and the organic or inorganic dye or pigment particles 8 are dispersed and mixed only in the low refractive index layer 11.

With such a film structure, the conductive filler particles 9 originally have a very high refractive index, so that the concentration of the conductive filler particles 9 in the high refractive index layer 10 increases. The refractive index of the film itself can be increased to about 1.95 from about 1.8 in the first embodiment. Similarly, since the conductive filler particles 9 having a high refractive index do not exist in the low refractive index layer 11, the refractive index of the film itself is about 1.4 compared to about 1.42 in the first embodiment.
Can be reduced to zero. Therefore, the optical characteristics of the low reflection film are greatly improved. FIG. 1D shows the surface spectral reflectance of the antistatic light selective absorption type low reflection film (two layers) in the case of the third embodiment, which is reduced to 0.8% in the visible light region average. Incidentally, in the case of the two-layer product of Example 1, the surface spectral reflectance was about 1.2% in the visible light region average.

(M "') to (p"') of FIG.
Low reflection film according to the third embodiment on the outer surface of the base plate 2
The intensity of the reflected light (E₁ , E_Two ) And surface anti
The rate of shooting "[E₁ / (E₁ + E_Two )] × 100 ”
In the case of the two-layer product of Example 1,of
As compared with (m ′) to (p ′), the ratio of external light reflected from the surface isExample
In case of 1It has been reduced to about 70%,
Good is being done.

In the case of this embodiment, the low refractive index layer 11 is used.
About ultrafine magnesium fluoride (MgF ₂ ) 1
Even if 4 is not added, a certain low refractive index (about 1.45)
Therefore, it is also possible to use an alcohol solution of an alkoxide of silicon (Si) as the low refractive index base paint.

Embodiment 4 FIG. 5 is a diagram showing a film configuration of an improved low reflection film 12 formed by combining four layers of a high refractive index layer 10 and a low refractive index layer 11 similarly to the case of the second embodiment. FIG. 4 is an enlarged conceptual sectional view of a face plate portion of a cathode ray tube with a low reflection film according to the present invention. In this case, the refractive index of the high-refractive-index layer 10 can be set higher and the refractive index of the low-refractive-index layer 11 can be set lower than in the case of the second embodiment by the same method as that described in the third embodiment. The optical properties of the film 12 are greatly improved.

FIG. 1E shows the surface spectral reflectance of the anti-static light selective absorption type low reflection film (four layers) in the case of Example 4, which is reduced to 0.25% in the visible light region average. Can be done.

In the first to fourth embodiments, the antistatic selective absorption type low reflection film is mainly described. However, the present invention is not limited to this, and the face having a light transmittance of 50% or less is not limited to this. A film having only an antistatic function on the outer surface of the plate 2, a film having only a light selective absorption function, or a film having neither of these functions;
The same applies to the case of forming a film having only a low reflection function.

[0057]

As described above, according to the present invention, even when a face plate having a light transmittance of 50% or less is used, the alkoxide of silicon (Si) provided on the outer surface of the face plate is used. And a low-reflection layer composed of a combination of at least two and no more than four high-refractive-index layers and a low-refractive-index layer formed by dispersing ultrafine high-refractive material or low-refractive material therein. The film reduces external light reflection on the outer surface of the face plate,
There is an effect that a large amount of a high quality cathode ray tube with a low reflection film can be obtained by an inexpensive method with little influence of reflection from outside light.

[Brief description of the drawings]

FIG. 1 is a diagram showing spectral reflectances of a face plate portion and a low reflection film of a cathode ray tube.

FIG. 2 is an enlarged conceptual sectional view of a two-layer low reflection film.

FIG. 3 is an enlarged conceptual sectional view of a four-layer low-reflection film.

FIG. 4 is an enlarged conceptual sectional view of an improved two-layer low-reflection film.

FIG. 5 is an enlarged conceptual sectional view of an improved four-layer low-reflection film.

FIG. 6 is a diagram showing the degree of reflection on the outer surface of the face plate of the cathode ray tube.

FIG. 7 is an enlarged schematic sectional view of a fluorescent screen portion of a cathode ray tube with a light selective absorption film.

FIG. 8 is an enlarged schematic sectional view of a fluorescent screen portion of a cathode ray tube.

FIG. 9 is an enlarged conceptual sectional view of an antistatic light selective absorption film.

FIG. 10 is a diagram showing a spectral transmittance distribution of a face portion and the like of a cathode ray tube.

FIG. 11 is a view showing the structure of a cathode ray tube with an antistatic light selective absorption film.

FIG. 12 is a diagram showing a change in surface potential of a face plate portion of a cathode ray tube.

FIG. 13 is a diagram showing an emission spectrum distribution of an incandescent lamp for surface reflection measurement and evaluation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cathode ray tube with antistatic light selective absorption film 2 Face plate 3 Antistatic light selective absorption film 4 BGR three color phosphor layer 5 Metal back film 6 Black light absorption film 7 Porous silica film 8 Organic or inorganic dye or Pigment particles 9 Conductive filler particles 10 High refractive index layer 11 Low refractive index layer 12 Low reflection film 13 Ultrafine titanium oxide (TiO ₂ ) 14 Ultrafine magnesium fluoride (MgF ₂ )

Claims (6)

(57) [Claims] 1. A high-refractive-index layer and a low-refractive-index layer of two to four layers based on silicon (Si) alkoxide are provided on a face plate portion of a cathode ray tube having a light transmittance of 50% or less. What is claimed is: 1. A cathode ray tube provided with a low-reflection film having a low-reflection film formed of a multilayer optical interference film formed by an alternate lamination combination, wherein the low-refractive-index layer has a functional group of -OH group, -OR
Alcohol solution of silicon (Si) alkoxide having a group or an alcohol solution having an average particle size of 100
A high-refractive-index layer is formed by coating a low-refractive-index base paint obtained by dispersing and mixing ultrafine magnesium fluoride (MgF ₂ ) having a particle size of 0 ° or less. Ultrafine tantalum oxide (Ta ₂ O ₅ ) and ultrafine titanium oxide (Ti) having an average particle size of 1000 ° or less with respect to an alcohol solution of an alkoxide of Si)
O ₂ ), one of ultrafine zirconium oxide (ZrO ₂ ) or ultrafine zinc sulfide (ZnS), or a mixture of these, dispersed and mixed, and formed by a coating film of a high refractive index base paint. A cathode ray tube provided with a low reflection film. 2. When alternately laminating coating films to be a high-refractive index layer and a low-refractive index layer, after forming a coating film of a certain layer, a base coat is formed before forming a next coating film on the film surface. The cathode ray tube with a low reflection film according to claim 1, wherein the film is cured. 3. The cathode ray tube with a low reflection film according to claim 1, wherein each coating film is formed by a spin coating method. 4. A base paint for forming each coating film,
The cathode ray tube with a low reflection film according to any one of claims 1 to 3, wherein an organic or inorganic dye or pigment is dispersed and mixed. 5. A base paint containing tin oxide (SnO ₂ ) or indium oxide (In ₂ O ₃ ) as a conductive filler.
The cathode ray tube with a low reflection film according to any one of claims 1 to 4, wherein conductive fine particles such as the above are dispersed and mixed. 6. The cathode ray tube with a low reflection film according to claim 5, wherein a conductive filler is dispersed and mixed only in the high refractive index base paint.