JPH103868A - Cathode ray tube and method of manufacturing the same - Google Patents

Abstract

(57) [Problem] To provide a cathode ray tube capable of improving a leakage electric field shielding effect so as to cope with a leakage electric field intensity of 1.0 V / m or less, which is a guideline of TCO, and a method of manufacturing the same. SOLUTION: A high-refractive-index transparent conductive layer 2 made of Ag fine particles having an average particle diameter of 0.005 μm and having a surface resistance of 9 × 10 ² Ω / □ or less is formed on an outer surface of a face plate 1 by spin coating. And a low-refractive-index transparent layer 3 made of a silica film (SiO ₂ ) on the high-refractive-index transparent conductive layer 2.
Is formed by spin coating.

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 an antireflection film formed of a high-refractive-index transparent layer and a low-refractive-index transparent layer on a face plate, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, various coating films are formed on the surface of a face plate of a cathode ray tube to give various added values such as an antireflection function and an antistatic function. For example, as shown in JP-A-6-243803, it is well known that an antireflection effect can be obtained by using a two-layer optical thin film composed of a high refractive index transparent layer and a low refractive index transparent layer. . An antistatic effect can be obtained by forming a conductive film on the face plate and grounding the conductive film.

[0003] In addition to these, in recent years, a leaked electric field shielding function has attracted attention as a function required for a cathode ray tube. This is a VLF (Very Low Frequency) emitted from a display monitor in which a cathode ray tube is incorporated.
y: band 2 kHz to 400 kHz) and ELF (Extr)
a Low Frequency: 5 Hz to 2 kHz band
z) is based on the background that regulations on electromagnetic waves have become stricter in recent years. In particular, the TCO guidelines established by the Swedish labor organization are the strictest among them, and are 30 cm from the face of the cathode ray tube.
At a position, the leakage electric field is 1.
It is required that the leakage electric field be 10 V / m or less for an alternating electric field in the ELF band of 0 V / m or less.

[0004]

On the other hand, the conventional antistatic conductive film or antireflection film cannot stably achieve this value. According to JP-A-5-343007, a high-refractive-index transparent layer has a surface resistance of 5 × 10 ^3.
It is stated that if the conductive film is Ω / □ or less or 3 × 10 ³ Ω / □ or less, the TCO guidelines can be satisfied. However, due to manufacturing variations, the predetermined performance is not necessarily achieved as shown in FIG. There was a problem that it could not be obtained. FIG. 9 shows the target surface resistance of the high refractive index transparent conductive layer set in the manufacturing process on the horizontal axis, and the leakage of the cathode ray tube having the high refractive index transparent conductive layer formed in the manufacturing process for obtaining the target surface resistance. The vertical axis represents the distribution of the electric field strength, and there are some which cannot meet the TCO guidelines even if they are formed by a manufacturing process having the same target surface resistance value. In addition, in order to obtain a stable leakage electric field shielding characteristic, a means for ensuring the conductivity between the conductive film and the ground portion, that is, a reliable grounding method from the conductive film is required.

As a transparent conductive material for forming a conductive film,
Conventionally, metal oxides such as ITO (tin-doped indium oxide) and ATO (antimony-doped tin oxide) have been well known, and have already been put to practical use for transparent electrodes and the like. Coatings for imparting conductivity to the surface of the cathode ray tube are also at a practical level, and a multilayer film having two or more layers and having a low reflectance is used for antistatic purposes and the like. Also in this case, if the thickness of the conductive layer is increased ignoring the optical characteristics, the resistance value of the surface decreases, and for example, the effect of suppressing the leakage electric field can be expected. However, except for the case where a continuous film is formed by a method such as evaporation or sputtering to reduce the resistance, the fine particles are formed of silica (Si).
In the method of connecting with the O ₂ ) component or the like, the resistance value of the fine particles themselves is high, and the desired resistance value cannot be obtained.

[0006] Methods for achieving the TCO guidelines by methods other than surface coating include the following. (1) A glass plate (Anti-Reflection P) on which a low reflective and conductive multilayer film is formed by a vapor deposition method
late) to the face plate surface. (2) Countermeasures are taken on the circuit side, such as adding an electric field canceling coil to the cathode ray tube. However, those using a glass plate that is expensive and requires a lot of labor to attach have a problem that the price of the cathode ray tube is high, and measures for the circuit also require extra cost for the circuit cost. There is a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and can improve the shielding effect of a leaked electric field so as to cope with a leaked electric field strength of 1.0 V / m or less, which is a TCO guideline. An object of the present invention is to provide a cathode ray tube and a method for manufacturing the same.

[0008]

A cathode ray tube according to the present invention comprises a high refractive index transparent conductive layer formed on the outer surface of a face plate and a low refractive index transparent conductive layer formed on the high refractive index transparent conductive layer. In the cathode ray tube provided with the layer, the transparent conductive layer having a high refractive index contains metal fine particles as a main component and has a surface resistance of 9
× 10 ² Ω / □ or less.

[0009] Further, as the metal fine particles, at least one of a group Ib metal and a metal group consisting of platinum, palladium, rhodium and iridium is used. The metal fine particles are a mixture of at least one of gold and silver and at least one of platinum, palladium, rhodium and iridium. Further, a terminal for grounding the high-refractive-index transparent conductive layer is provided, and one terminal is provided at the center of each of four sides of the high-refractive-index transparent conductive layer. Furthermore, the high-refractive-index transparent conductive layer has a terminal for grounding, and two terminals are provided on each of two opposing sides of the high-refractive-index transparent conductive layer.

[0010] In addition, a terminal for grounding the high refractive index transparent conductive layer is provided, and the terminal and the grounding portion are connected with the same material as the terminal forming material. Also,
The material for forming the terminal is solder, conductive resin, or conductive frit glass.

In the method of manufacturing a cathode ray tube according to the present invention, a step of preheating so that the temperature difference of the outer surface of the face plate becomes 5 ° C. or less, and a step of dispersing metal fine particles on the outer surface of the preheated face plate. The method includes a step of applying a liquid by a spin coating method to form a high refractive index transparent conductive layer, and a step of forming a low refractive index transparent layer made of a silica film on the high refractive index transparent conductive layer.

After the formation of the low refractive index transparent layer, 160 to
It includes a step of firing at a temperature of 250 ° C. Further, a step of applying a water dispersion of fine metal particles to the outer surface of the face plate by a spin coating method to form a high refractive index transparent conductive layer, and attaching a grounding conductive tape to the high refractive index transparent conductive layer. And a step of forming a low refractive index transparent layer made of a silica film on the high refractive index transparent conductive layer to which the conductive tape is attached.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, Embodiment 1 of the present invention will be described. As a conductive film material, a material such as a metal which itself has a very low resistance value, but a material which cannot normally obtain transparency has not been sufficiently used. When the thickness of the metal becomes 100 nm or less, transparency is obtained, and the thickness becomes 10 nm.
It is known that the transmittance is about 10% when the thickness is about the same. First of all, we focused on metal fine particles and conducted experiments mainly on precious metals that can be kept relatively stable even in the fine particle state, and found that ultrafine particles of gold and silver can be formed without redox reaction. Was. Similarly, the fine particle state is maintained by performing a special treatment on the group Ib copper and platinum, palladium, rhodium and iridium,
Conductivity and transparency were observed.

FIG. 1 is a schematic cross-sectional view of a main part showing a first embodiment. In FIG.
Is a high-refractive-index transparent conductive layer formed on the outer surface of the face plate 1 and is made of Ag fine particles having an average particle size of 0.005 μm, and has a surface resistance of 9 × 10 ² Ω / □ or less. . Reference numeral 3 denotes a low-refractive-index transparent layer formed of a silica film (SiO ₂ ) formed on the high-refractive-index transparent conductive layer 2. In order to obtain the maximum low reflection effect, the optical film thickness (refractive index × film thickness) of each layer of the face plate portion is set to one of the wavelengths of the incident light.
/ 4. As the wavelength of the incident light, a value at a wavelength of 530 nm to 550 nm at which the visibility increases is used. For example, when Ag is used as the metal fine particles, the refractive index value n1 of the high refractive index transparent conductive layer 2 is 2.26, the refractive index value n2 of the low refractive index transparent layer 3 is 1.47, and the film thickness is high. The transparent conductive layer 2 has 586 ° and the low refractive index transparent layer 3 has 901 °.

Fine particles of a metal belonging to the group Ib and selected from the group consisting of platinum, palladium, rhodium and iridium are used as the high refractive index transparent conductive layer 2. The average particle diameter of the fine particles is about 0.005 μm on average. The film is good, and if it is 0.01 μm or more, a reflectance of 2% or less cannot be obtained. On the other hand, when the ratio of particles having a size of 0.1 μm or more exceeded 5%, a reflectance of 4% or less was not obtained. On the other hand, in the case of coexistence with other oxide particles, a sufficient resistance value cannot be obtained with a film thickness capable of obtaining the reflection characteristics. It is necessary to form the high-refractive-index transparent conductive layer 2 only with metal fine particles. When the low-refractive-index transparent conductive layer 3 is formed, for example, a silica component is previously contained in the high-refractive-index transparent conductive layer 2 in addition to the metal fine particles. If the volume ratio is 5% or more, sufficient contact of the metal fine particles cannot be obtained, and a sufficient resistance value cannot be obtained by setting the reflectance to 2% or less.

Next, the manufacturing process of the coating film according to the present invention will be described. FIG. 2 shows a flowchart of the manufacturing process. The temperature of the face plate portion of the cathode ray tube is raised to 40 to 50 ° C. in a preheating furnace, and then put into a spin booth. After that, first, an aqueous dispersion of Ag fine particles (average particle size 0.005 μm) is injected into the face surface, and the high refractive index transparent conductive layer 2 is formed by spin coating. Next, after drying this high refractive index transparent conductive layer 2, a silica film (S
iO ₂ ) is formed by spin coating. The above operations in the spin booth are performed continuously, and the time schedule and the number of revolutions of the spin coat at that time are set as shown in Table 1.

[0017]

[Table 1]

After spin coating of the low refractive index transparent layer 3, the cathode ray tube was taken out of the spin booth, and then baked and cured at 200.degree. Thereafter, as shown in FIG. 3 (a), one terminal 6 is provided at the center of each side by solder so as to reach the high refractive index transparent conductive layer 2, and is wound around the side surface of the face plate and grounded. The high refractive index transparent conductive layer 2 was grounded by being connected to the metal explosion-proof band 5 with the conductive tape 7. When the cathode ray tube provided with the coating film formed as described above was evaluated, the surface resistance was 7 × 10 ² Ω / □, the surface reflectance was 0.3%, the leakage electric field strength was 0.6 V / m, and the TCO Characteristics that clear the guidelines were obtained. Note that, as shown in FIGS. 3B and 3C, the same characteristics were obtained even when two terminals 6 were provided on one of the opposite sides of the high refractive index transparent conductive layer, respectively. That is, it is desirable to provide the terminal 6 so as to have a symmetrical positional relationship with respect to the center of the face plate.

When the number of revolutions of the spin coating for forming the high refractive index transparent conductive layer 2 is changed, the film thickness changes and the surface resistance value also changes. Also, even if the films have the same surface resistance,
The leakage electric field strength varies depending on the number of terminals 6. FIG.
FIG. 4 is a diagram showing changes in leakage electric field strength when there are two, four, and six terminals 6. As is clear from FIG. 4, if it is assumed that the variation in the manufacturing process can be reduced by thoroughly controlling the temperature and humidity and controlling the material in order to clear the TCO guideline (1 V / m), the terminal 6 is required. It is understood that a surface resistance value of 9 × 10 ² Ω / □ or less is required for four pieces. Terminal 6 is 2
In the case of the individual terminals, 2 × 10 ² Ω / □ or less is required to obtain the same characteristics. However, the number of terminals 6 is set to four in consideration of the margin for the surface resistance value and the productivity. From the setting of the surface resistance value, the spin rotation speed was about 150 rpm. If the amount of electromagnetic waves generated by the improvement of the deflection yoke, etc., which is the source of electromagnetic waves, is reduced, the characteristic curves in FIG. Needless to say.

The purpose of baking after film formation is to increase the film strength. However, as shown in FIG. 5, the refractive index changes as the baking temperature changes, that is, the film strength changes, and a low reflection effect is intended. The wavelength shifts. Also, if the film is too hard,
It also affects the face plate and causes cracking of the face plate. For this reason, the firing temperature is at most 25.
About 0 ° C. is appropriate, and in order to obtain a stable reflection characteristic (wavelength position), it is necessary to suppress a change in the refractive index to about 0.5%, and firing at 160 to 250 ° C. withstands use as shown in FIG. Range.

Although the formation of a thin film on the outer surface of the face plate by the spin coating method has already been put to practical use,
Conventionally, it has been difficult to spin coat metal fine particles as a multilayer film so as to have sufficient reflection characteristics and low resistance. The first reason is that metal fine particles suitable for the spin coating method cannot be stably obtained. Therefore, in order to obtain stability, a preheating method was employed in which the surface temperature of the face plate immediately before the spin coating step when forming the high refractive index transparent conductive layer 2 was kept sufficiently uniform, and the maximum temperature difference was kept at 5 degrees or less. . As a result, aggregation of the metal fine particles can be suppressed, and spin coating can be performed.

Embodiment 2 FIG. In the first embodiment, the high-refractive-index transparent conductive layer 2 is mainly composed of Ag. However, Au, Cu, Pt, Pd, R
h, Ir. The surface resistance when formed using a dispersion of Au fine particles was 6 × 10 ² Ω / □. However, the time schedule and the number of rotations of the spin coating were set as shown in Table 2.

[0023]

[Table 2]

Further, the surface resistance values when formed using a dispersion of fine particles of Cu, Pd, Pt, Rh, and Ir were all 9 × 10 ² Ω / □. However, the time schedule and the number of rotations of the spin coating were set as shown in Table 3.

[0025]

[Table 3]

As described above, metals of the group Ib and platinum,
By using metal fine particles selected from the metal group consisting of palladium, rhodium, and iridium, a high refractive index transparent conductive layer 2 having characteristics that meet the guidelines of TCO can be obtained. By the way, as is generally known, Ag and Au have high reactivity with Group 7B elements such as Cl. Therefore, when Ag and Au are used as the metal fine particles, the stability of the resistance value of the film is taken into consideration. It is better to mix at least one of Pt, Pd, Rh, and Ir. By substituting a part of Ag and Au with Pd or Pt, the reactivity can be lowered and desired characteristics can be stably obtained. Although the characteristics depend on the mixing ratio, for example, in the case of a mixture of Ag and Pd, the reactivity is suppressed as the ratio of Pd is increased. Can not be obtained. In order to ensure the stability of the resistance value of the film, Pd needs to be about 20% by weight or more. However, if it exceeds 60% by weight, the resistance value rises rapidly and cannot be used as a surface coating film.
The ratio of d is preferably in the range of 20 to 60% by weight. As described above, a high-quality film structure as a surface coat film is formed by mixing the metals of the group Ib and a plurality of metals selected from the group consisting of platinum, palladium, rhodium and iridium at an appropriate ratio. be able to.

In the first and second embodiments, the spin-coating method is used to form the high-refractive-index transparent conductive layer 2. However, Au, Ag, and Cu films are directly deposited on the outer surface of the face plate 1 by vapor deposition. The same effect can be obtained by forming the same.

Embodiment 3 In the first embodiment, in order to obtain the ground of the high refractive index transparent conductive layer 2 as shown in FIG.
After forming the terminal 6 with solder, connection to the metal explosion-proof band 5 was performed with the conductive tape 7. However, in the third embodiment, as shown in FIG. 6, the terminal 6 was formed with solder, conductive resin, or conductive frit glass. And connected directly to the metal explosion-proof band 5 with this terminal forming material. When the resistance value of the terminal 6 is 1.5 times or less the resistance value of the high refractive index transparent conductive layer 2, good conduction is obtained.
If it exceeds five times, it is necessary to take measures such as increasing the number of terminals 6. As shown in FIG. 4, the relationship between the surface resistance value and the leakage electric field strength varies depending on the number of terminals 6,
These relationships are for the case where the resistance value of the terminal 6 is 1.5 times or less the resistance value of the transparent conductive layer 2 having a high refractive index. If the resistance value exceeds this value, it is necessary to increase the number of terminals. When solder is used as a material for forming the terminal 6, it is easy to make the resistance value 1.5 times or less of the transparent conductive layer 2 having a high refractive index. When a conductive resin and conductive frit glass are used, an effective leakage electric field shielding effect can be obtained when the resistance value is 1.5 times or less that of the high refractive index transparent conductive layer 2.

When a conductive resin is used as the terminal material, a terminal coating step can be provided before the baking step, and conduction with the high refractive index transparent conductive layer 2 can be formed with higher reliability. The state of the surface before the firing step is microscopically porous, and the structure is such that the terminal material easily reaches the high refractive index transparent conductive layer 2 even after the film is formed on the outer surface of the face plate. It is not necessary to use a material whose reactivity with the temperature or the glass material is increased, and it is possible to form a sufficient terminal 6 by a simple operation.

However, especially in applications where the surface condition of the face plate is required to be strong, after baking sufficiently after forming the surface film to increase the film strength, the high refractive index transparent conductive film is passed through the strong film. It is effective to use a glass solder capable of obtaining sufficient conduction with the layer 2 and use ultrasonic waves or the like for an auxiliary action, which has been confirmed to be more effective. When conductive frit glass is used, it is effective to provide a conductive frit glass coating step before the baking step, and to adhere in the baking step, but it is effective to select a component that matches the baking step It is. In this case or when a frit glass attaching step is provided after firing, the effect of the terminal can be enhanced by providing a frit glass baking step of a local heating method.

Embodiment 4 FIG. In the first embodiment, after forming the high-refractive-index transparent conductive layer 2 and the low-refractive-index transparent conductive layer 3, a terminal 6 is formed by soldering and a conductive tape 7 Although connection was made to the metal explosion-proof band 5, in the fourth embodiment, as shown in FIGS. 7 and 8, immediately after forming the high-refractive-index transparent conductive layer 2, The tape is grounded to the metal explosion-proof band 5 with a tape 7, and then a post-process is performed.

[0032]

In the cathode ray tube according to the present invention, the high refractive index transparent conductive layer formed on the outer surface of the face plate contains metal fine particles as a main component and has a surface resistance of 9 × 10 ² Ω /.
□, the TCO guideline of a leak electric field strength of 1 V / m or less can be reliably achieved with the cathode ray tube alone without impairing the low reflection effect even when manufacturing variations are considered.

Further, since at least one kind of metal of the group Ib and a metal group consisting of platinum, palladium, rhodium and iridium is used as the fine metal particles, a transparent material having a high refractive index having a surface resistance of 9 × 10 ² Ω / □ or less is used. A conductive layer can be easily realized. Further, since the metal fine particles are a mixture of at least one of gold and silver and at least one of platinum, palladium, rhodium and iridium, a high-quality film structure having a stable resistance value can be obtained.

Further, since one terminal for grounding the transparent conductive layer with a high refractive index is provided at the center of each of the four sides of the transparent conductive layer with a high refractive index, or at each of two opposite sides thereof, The high refractive index transparent conductive layer can achieve both a margin with respect to the surface resistance value and productivity. Furthermore, since the terminal for grounding the high refractive index transparent conductive layer is provided, and the terminal and the grounding portion are connected by the same material as the terminal forming material, it is not necessary to attach a conductive tape, thereby reducing the manufacturing cost. it can.

Further, since the material for forming the terminal is made of solder, conductive resin or conductive frit glass, a highly reliable terminal can be obtained.

Further, in the method of manufacturing a cathode ray tube according to the present invention, spin coating is performed after preheating so that the temperature difference of the outer surface of the face plate becomes 5 ° C. or less. The high refractive index transparent conductive layer can be formed by spin coating.

The firing temperature after the spin coating is set to 160
Since the temperature is set to ２５０250 ° C., a film having stable reflection characteristics can be formed while securing the film strength.

Further, since the low refractive index transparent layer is formed after the grounding conductive tape is attached to the high refractive index transparent conductive layer, there is no need to provide a special terminal for grounding, and the manufacturing cost is reduced. Can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a manufacturing process diagram showing a method for manufacturing a cathode ray tube according to Embodiment 1 of the present invention.

FIG. 3 is a schematic plan view showing a grounding structure according to the first embodiment of the present invention.

FIG. 4 is a characteristic diagram for explaining the number-of-terminals dependence of a surface resistance value and a leakage electric field intensity.

FIG. 5 is a characteristic diagram showing a relationship between a firing temperature and a refractive index.

FIG. 6 is a schematic plan view showing a grounding structure according to a third embodiment of the present invention.

FIG. 7 is a manufacturing process diagram showing a method for manufacturing a cathode ray tube according to Embodiment 4 of the present invention.

FIG. 8 is a schematic plan view showing a grounding structure according to a fourth embodiment of the present invention.

FIG. 9 is a characteristic diagram for explaining a change in leakage electric field intensity due to a variation in surface resistance value.

[Explanation of symbols]

1 face plate, 2 high refractive index transparent conductive layer, 3
Low refractive index transparent layer 5 Metal explosion-proof band, 6 Terminal, 7 Conductive tape

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsuya Kinoshita 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Mitsuhiro Okumura 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Rishi Electric Co., Ltd.

Claims (10)

[Claims] 1. A cathode ray tube comprising a high-refractive-index transparent conductive layer formed on an outer surface of a face plate and a low-refractive-index transparent layer formed on the high-refractive-index transparent conductive layer. A cathode ray tube characterized in that the transparent conductive layer contains metal fine particles as a main component and has a surface resistance of 9 × 10 ² Ω / □ or less. 2. The cathode ray tube according to claim 1, wherein at least one of a metal group Ib and a metal group consisting of platinum, palladium, rhodium and iridium is used as the metal fine particles. 3. The cathode ray tube according to claim 2, wherein the metal fine particles are a mixture of at least one of gold and silver and at least one of platinum, palladium, rhodium and iridium. 4. The high-refractive-index transparent conductive layer has a terminal for grounding, and one terminal is provided at each of the center portions of four sides of the high-refractive-index transparent conductive layer. Item 7. The cathode ray tube according to Item 1. 5. The high-refractive-index transparent conductive layer has a terminal for grounding, and two terminals are provided on each of two opposite sides of the high-refractive-index transparent conductive layer. The cathode ray tube according to claim 1. 6. The cathode ray tube according to claim 1, wherein the high-refractive-index transparent conductive layer has a terminal for grounding, and the terminal and the grounding portion are connected by the same material as the terminal forming material. 7. The cathode ray tube according to claim 6, wherein the material for forming the terminal is solder, conductive resin, or conductive frit glass. 8. The temperature difference of the outer surface of the face plate is 5
C., a step of applying a water dispersion of fine metal particles to the outer surface of the preheated face plate by a spin coating method to form a high-refractive-index transparent conductive layer, and The method for producing a cathode ray tube according to claim 1, further comprising a step of forming a low refractive index transparent layer made of a silica film on the high refractive index conductive layer. 9. After formation of the low refractive index transparent layer, 160 to 25
The method for manufacturing a cathode ray tube according to claim 8, comprising a step of firing at a temperature of 0 ° C. 10. A step of applying an aqueous dispersion of fine metal particles to the outer surface of the face plate by a spin coating method to form a high refractive index transparent conductive layer, and forming a conductive layer for grounding on the high refractive index transparent conductive layer. 2. The cathode ray tube according to claim 1, further comprising a step of attaching a tape and a step of forming a low refractive index transparent layer made of a silica film on the high refractive index transparent conductive layer to which the conductive tape is attached. Production method.