JPH0346737A - Antireflective and antistatic type cathode-ray tube and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain an antireflective and antistatic coat having excellence in resolution and in optical characteristics by forming a hyaline conductive film consisting principally of SnO2 particulates of a specified composition ratio and a specified film-thickness on the outside surface of a panel and subsequently forming a minute irregular film consisting principally of SiO2 thereon. CONSTITUTION:On the outside surface of a panel 10 is formed a hyaline conductive film 20 consisting principally of SnO2 particulates of an average particulate diameter below 2,000Angstrom , whose composition ratio by weight is SnO2/SiO2>=0.8 and whose thickness ranges from 100 to 3,000Angstrom . On this conductive film is formed a minute irregular film 21 consisting principally of SiO2, whose average thickness d<2> is about 1,000Angstrom , whose irregular pitch P ranges from about 15 to about 20 micrometers, whose surface roughness Rz is about 0.5 micrometer and whose light intensity Gs on a screen is about 55%. This results in obtainability of an antireflective and antistatic coat having excellent conductivity, reflectance without dependence on humidity, low deterioration both in reflected colors and in resolution, and yet having great wear resistance.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention forms a reflective antistatic film on the outer surface of the face plate of a glass bulb in order to prevent reflection of external light and charging of a display area. The present invention relates to a reflective antistatic cathode ray tube and a method for manufacturing the same.

(Prior Art) When a high voltage is applied to a phosphor screen formed on the inner surface of a face plate of a cathode ray tube, the outer surface of the face plate, on which the phosphor screen is formed, becomes electrically charged transiently. In order to prevent this charging, some cathode ray tubes have conventionally had an antistatic film made of a transparent conductive film formed on the outer surface of the face plate.

As the transparent conductive film material, SnO, sb
SnO doped with (SnOa:Sb), or In, O.

or Sn-doped In2O, (In, O,: Sn)
(hereinafter referred to as ITO), etc. However, since these transparent conductive film materials have a high refractive index of about 2.0, these materials can be used to form a transparent conductive film on a glass surface with a refractive index of about 1.52. If formed, the specular reflectance will be higher than when only the glass surface is used, and the reflection characteristics will deteriorate.

As a means to solve this deterioration of reflection characteristics,
JP-A-381, JP-A No. 60-168102, JP-A-60-168899, etc. disclose a multilayer antireflection film, at least one of which is a transparent conductive film such as In2O or ITO. The structure is shown in which the characteristics of anti-static and static-static properties are taken into account. The techniques disclosed in these publications all have a common feature in that a smooth film is formed by vacuum evaporation or sputtering, and antireflection is achieved only by the interference effect.

However, if the thickness of a multilayer anti-reflection film made of a smooth film is insufficiently controlled, interference colors will occur, resulting in inconveniences such as different reflected colors in different parts of the display or different colors depending on the display device. occurs. Therefore, when forming such a multilayer anti-reflection film, it is necessary to control the film thickness with high precision using vacuum evaporation or sputtering, and if this is applied to cathode ray tubes, the equipment will become larger and manufacturing costs will rise. This will lead to a decline in manufacturing capacity.

In addition to the above-mentioned method of obtaining the anti-reflection characteristic by interference effect, there is a method of providing unevenness on the outer surface of the face plate of the cathode ray tube to blur the reflected image by a magnification effect.

JP-A-61-118932, JP-A-61-118
No. 946 and Japanese Unexamined Patent Publication No. 62-37850 disclose a method of imparting conductivity to an uneven surface without using a conductive film with a high refractive index. For example, JP-A-61-118
932, as shown in Figure 4, HNO,
After spraying an alcoholic solution of Si(OR)4 (R is an alkyl group) to which 80 to 15
A method is disclosed in which the uneven film (2) is formed by firing at a temperature of 0°C. In FIG. 4, (4) is a phosphor screen formed on the inner surface of the face plate.

However, as shown in Figure 5, the conductivity of the uneven film (2) is based on the hygroscopicity due to the hydrogen bonding of the silanol groups (Si-OH) present in the Sun and silanol groups (Si-OH) present in the layer. Therefore, the conductive performance is dependent on humidity, and the silanol group is unstable in a humid environment. Furthermore, since it is fired at a low temperature, there are problems such as weak film strength.

Furthermore, as shown in Fig. 6, Japanese Utility Model Publication No. 49-24211 discloses that a transparent conductive film (■) is formed on the outer surface of the face plate (■) of a glass bulb of a cathode ray tube, and an alkali silicate film (2) is formed on this transparent conductive film (■). A protective coating of salt (■) is shown. The transparent conductive film (■) and the protective film (0) are formed by forming a transparent conductive film (2) by a spray method, and then a 10% aqueous alkali silicate solution having a molar ratio of 3.4 to 5 in2/20 is applied onto the transparent conductive film (2) using a nozzle inner diameter of 0. An alkali silicate film was formed by spraying with a No. 41 spray gun, and then heat-treated at about 450° C. for 30 minutes to solidify it.

In this example, the spray method is used as the film formation method, so the surface of the film is not smooth but has some degree of unevenness, making it possible to obtain a reflective antistatic film at a relatively low cost. is expected.

However, this method uses an aqueous alkali silicate solution and the solution viscosity is relatively high, so no matter how devised the spray method is, it is not easy to form a textured film with good optical properties such as resolution. . Also, S containing alkali generally
The refractive index of iO2 is the refractive index of only SiO□ (approximately 1.46
), the antireflection effect of the two layers decreases.

In addition, a transparent conductive film is formed on the outer surface of the face plate of the glass bulb of the cathode ray tube by the CVD method, and an alcohol solution of 5i (OR) is sprayed onto this transparent conductive film and then baked to form fine irregularities of SiO2. There is a method in which a reflective antistatic film is formed by forming an antireflective film.

Furthermore, as shown in Fig. 7, JP-A-63-76247 discloses that after spraying an alcohol solution of 5i (OR) on the outer surface of the face plate of the glass bulb of a cathode ray tube, , to form fine irregularities WX■ at a temperature of 150°C for 30 minutes.Then, the cathode ray tube on which the uneven film ■ has been formed is placed in an atmospheric pressure CVD apparatus, and the outer surface of the face plate ■ is approximately A method is disclosed in which a transparent conductive film (2) of SnO and In2O3 is formed to a thickness of about 1000 nm on the uneven film (2) by heating to 350°C. This transparent conductive film (2) can be formed in an atmospheric pressure CVD film forming chamber using a belt conveyor that sequentially transports cathode ray tubes.

In this example, the uneven film (1) is formed by a spray method, and the transparent conductive film (8) is formed by a relatively easy normal pressure CVD device, so it has a two-layer anti-reflective structure with excellent conductivity and reflectivity. Membranes can be produced at relatively low cost. However, in this method, SnO□ and In, 03 are
Since the bonding is carried out at a low temperature of 0° C., the bonding of SnO2 is incomplete and the abrasion resistance of the transparent conductive film (1) is low. In addition, due to the manufacturing process of cathode ray tubes, processing after evacuation is not possible, so after the transparent conductive film is formed, appearance defects such as scratches and dust adhesion are likely to occur, and furthermore, it is impossible to recover and recycle them. There is.

(Problems to be Solved by the Invention) As mentioned above, conventional attempts have been made to obtain the antireflection properties of the reflective antistatic coating of cathode ray tubes only by interference effects.
There are also some that suppress reflection by having an uneven surface. However, none of these reflective antistatic films has a low reflectance, does not produce reflective interference colors, has little resolution degradation, and has good moisture resistance. Difficult to form.

This invention was made in view of the above problems, and
By solving the problems of conventional cathode ray tube reflective antistatic coatings,
The object of the present invention is to form a reflective antistatic film made of a finely textured film that practically satisfies both antireflection and antistatic properties.

[Structure of the invention]

(Means for Solving Problem 141) In a reflective antistatic cathode ray tube, on the outer surface of the face plate of the glass bulb, SnO with an average particle size of 2000 Å or less, with a weight composition ratio of 5 nOs mainly composed of fine particles.
A transparent conductive film having a film thickness of 100 to 3000 layers with SiO2≧0.8 was formed, and a fine unevenness film containing SiO as a main component was formed on this transparent conductive film to obtain a reflective antistatic film.

In addition, as a method for manufacturing the reflective antistatic cathode ray tube,
On the outer surface of the face plate of the glass bulb, Si(O
R) Apply the alcohol solution in step 4 to form a transparent conductive film, then preheat the face plate on which the transparent conductive film is formed to 50 to 90°C, and remove the transparent conductive film on the outer surface of the preheated face plate. An alcohol solution of 5i (OR) is sprayed on the film to form a finely textured film containing 5in2 as the main component, and the face plate on which this finely textured film is formed is baked at 150 to 350°C to achieve reflective charging. A preventive film was formed.

(Function) As mentioned above, the main component is SnO fine particles with an average particle size of 2000 Å or less, and the weight composition ratio is 5n02/SiO2≧0.
．． When the transparent conductive film of No. 8 is formed, a low resistance transparent conductive film with excellent moisture resistance is obtained, and even when baked at a temperature of 150 to 350°C, which is suitable for cathode ray tube processing, the surface resistance is 10"Ω/d.
It can be made to have a film strength as low as below, exhibit excellent conductivity, and have a practically satisfactory film strength. Moreover, since the single reflective antistatic film is composed of a conductive film having a refractive index that is almost the same as the refractive index nα1.52 of glass and a SiO□ film with a refractive index n=1.46, the film thickness of the transparent conductive film is 100~1.52. Even when the thickness is 3,000 people, there is no deterioration of reflectance or reflected color due to interference effects, and the antireflection properties are similar to those of the SiO uneven film alone, resulting in diffuse reflection, and compared to a single layer structure of a transparent conductive uneven film. , the resolution deteriorates due to the opacity of Haze.

It is possible to obtain a reflective antistatic film that exhibits excellent optical properties.

(Example) The present invention will be described below based on an example with reference to one drawing.

FIG. 1 shows a color picture tube on which a reflective antistatic film is formed, which is an embodiment of the present invention. This color picture tube includes a bulb (12) consisting of a panel (10) made of glass and a funnel (11) that are bonded together, and a fluorescent light made of a three-color phosphor layer formed on the inner surface of the panel (10). A reflective antistatic film (13) is formed on the outer surface of the panel (10) facing the body screen (A). In Fig. 1, (14) is a shadow mask mounted inside the panel (10) facing the phosphor screen a), and (15) is a shadow mask disposed inside the neck (16) of the funnel (11). The electron gun (17) is a reinforcing band that tightens the outer wall of the panel (10), and the reflective antistatic film (13)
is connected to the reinforcing band (17) by any means such as a metal piece (not shown), and the reinforcing band (17
).

As shown in an enlarged view in FIG. 2, the reflective antistatic film (13) is composed mainly of SnO fine particles with an average particle size of 2000 Å or less formed directly on the outer surface of the panel (10), and has a weight composition ratio. Film thickness 1 where SnO,/SiO□□≧0.8
It consists of a transparent conductive film (20) of 00 to 3000 people and a finely uneven film (21) whose main component is SiO□ formed on this transparent conductive film (20).

The reflective antistatic film (13) is formed after the color picture tube is manufactured by a conventional method.

That is, a phosphor screen is formed on the inner surface of the panel, the panel on which the phosphor screen is formed and the funnel are joined together, and after the electron gun is sealed and evacuated, explosion-proof treatment is performed. First, the outer surface of the panel of the color image receiving device that has been subjected to explosion-proof treatment is cleaned and dried. Next, the average particle diameter (average-order particle diameter) of 200 people's fine particle SnO
By stably dispersing □, the weight composition ratio is SnO, /5jn2
A Si(OR)4 alcohol solution having a concentration of 0.95 is applied smoothly onto the cleaned and dried outer surface of the panel by, for example, a spin method and dried to form a transparent conductive film. Coating methods for this transparent conductive film include, in addition to the spin method, a roll method, a dip method, and a spray method, and any of these methods can be used.

Next, this transparent conductive film is preheated to about 60° C., and 5 l (OR) 4 alcohol solution is sprayed onto the preheated transparent conductive film using a two-fluid spray gun with a nozzle diameter of 0.4 m+. As a result, the weight composition ratio of the lower layer of 1 reflective antistatic film was SnO2/SjO□=0.9.
5, the average secondary particle diameter of SnO2 is about 1 ooo,
A transparent conductive film (20) having a film thickness d1 of approximately 2700 mm can be formed, and as an upper layer of this transparent conductive film (20),
The average film thickness d2 is about 1000, and the pitch P of unevenness is about 15.
~20p, a surface roughness Rz of about 0.5-, and a display surface gloss Gs (according to the 60 degree specular gloss method of JIS Z8741) of about 55%. did it.

SnO, /S on the outer surface of the panel of a 15-inch color picture tube
The reflective antistatic film of this example was formed with iO□z1.0, and its properties were measured. Table 1 shows the results. In the comparative example shown in Table 1, a single layer of transparent conductive film was formed on a 15-inch color picture tube by the same method.

Table 1 Ω/a! Rlum x y Eight pieces Example (two layers) Comparative example (single layer) 0 0 1.6% 3.2% 0.33 0.32 0.33 0.32 Approx. 2700 As can be seen from Table 1, In the case of transparent conductive film layer, S
The refractive index of the mixed layer of nO□ and 5in2 is n>1.47~1
．． 50, the luminous specular reflectance hardly deteriorates,
Further, the specular reflection color is approximately white with Xαyα0.33.

On the other hand, with the two-layer structure of this example, the luminous specular reflectance is R1um1l, 4% due to the diffusion effect of the finely textured film.
The specular reflection color becomes almost white with Xyα0.33. Furthermore, regarding conductivity, the resistance value has almost no humidity dependence, and the surface resistance value r = 10'Ω/d
It showed a low resistance value and was able to make it uniform over the entire outer surface of the panel.

As a result, we applied a high voltage of 25 kV to the phosphor screen of a color picture tube (15-inch color picture tube) that had a two-layer structure with this reflective antistatic film, and measured the potential change on the outer surface of the panel. As shown by the broken line (23) in Figure 3, in an untreated color picture tube without a reflective antistatic film, the surface potential does not attenuate for 20 minutes after high voltage is applied, but the reflective 1f In the color picture tube of this example on which the antistatic film was formed, the potential became zero in about 1 second after application of the high voltage, as shown by the solid line (24).

In addition, regarding wear resistance, eraser (Lion50/3
0), the reflective antistatic film on the outer surface of the panel was rubbed 200 times with a load of 1 kg applied, but the chicks did not peel off.

In the above example, an example of a reflective antistatic film and a method for manufacturing the same was described, but the transparent conductive film constituting the lower layer of this reflective antistatic film has a weight composition ratio of SnO□/
With 5i02≧0.8, by applying a coating liquid in which an average particle size (average - large particle size) of 50 to 500 SnO is dispersed, the weight composition ratio is 5nOz/SiO□□≧
0.8 and an average secondary particle diameter of 2000 Å or less, a transparent conductive film having a thickness of 100 to 3000 Å and having the required properties can be obtained.

In other words, when the weight composition ratio of SnO2/SiO2 is lower than 0.8, the SnO particles are not connected to each other,
SnO.

The conductive mechanism due to the SnO2 film decreases, and the conductive mechanism due to the silanol groups present in the SnO2 film increases. This conductive mechanism is unstable in a humid environment.

It goes without saying that the present invention can also be applied to cathode ray tubes other than color picture tubes.

〔Effect of the invention〕

On the outer surface of the face plate of the glass bulb of the cathode ray tube, a transparent conductive film with a thickness of 100 to 3000 people, which is mainly composed of SnO fine particles with an average particle size of 2000 Å or less and whose weight composition ratio is SnO2/SiO2 ≧0.8, is applied. When a reflective antistatic film is formed by forming a finely textured film mainly composed of SiO2 on this transparent conductive film, it has excellent conductivity due to low surface resistance, and the conductivity has almost no humidity dependence. Furthermore, even if the thickness of the transparent conductive film is increased, the reflectance and reflected color do not deteriorate, and the resolution does not deteriorate due to the diffusion effect of the finely textured film, and the reflective antistatic film has strong abrasion resistance. I can do it.

[Brief explanation of drawings]

1 to 3 are detailed explanatory diagrams of the present invention. FIG. 1 is a partially cutaway view of a reflective antistatic color picture tube as an embodiment of the invention, and FIG. Figure 3 is a diagram showing the structure of the film, Figure 3 is a diagram showing its antistatic properties, and Figure 4 is a conventional cathode ray in which an uneven film is formed by spraying an alcohol solution of Si (OR) with added INO. tube diagram,
Fig. 5 is a diagram for explaining the conduction mechanism of the uneven film, Fig. 6 is a diagram of a conventional cathode ray tube in which a transparent conductive film and an alkali silicate protective film are formed, and Fig. 7 is a diagram of a conventional cathode ray tube formed using normal pressure CVD. 1 is a diagram showing a main part of a conventional cathode ray tube in which a transparent conductive film and a concave-convex film made of SiO are formed by a method. 4... Phosphor screen 10... Panel 12... Bulb 13...
・Reflective antistatic film 20...Transparent conductive film 21...Fine unevenness film

Claims (2)

[Claims] (1) Formed on the outer surface of the face plate of a glass bulb, the main component is SnO_2 fine particles with an average particle size of 2000 Å or less, and the weight composition ratio is SnO_2/SiO_2≧0.
1. A reflective antistatic cathode ray tube comprising: a transparent conductive film having a thickness of 100 to 3000 Å; and a finely textured film mainly composed of SiO_2 formed on the transparent conductive film. (2) Apply an alcohol solution of Si(OR)_4 (where R is an alkyl group) in which SnO_2 fine particles with an average primary particle size of 50 to 500 Å are dispersed to the outer surface of the face plate of the glass bulb to form a transparent conductive film. The process and the face plate on which the transparent conductive film is formed are heated to 50 to 90°C.
a step of preheating the transparent conductive film on the preheated outer surface of the face plate, a step of spraying an alcohol solution of Si(OR)_4 on the preheated transparent conductive film to form a finely textured film mainly composed of SiO_2; 1. A method for manufacturing a reflective antistatic cathode ray tube, comprising the step of firing the face plate on which the film is formed at 150 to 350°C.