JPH0810580B2 - Antistatic type cathode ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention is intended to prevent the discomfort to the human body due to the adhesion of fine dust in the air due to the charging of the outer surface of the face plate portion and the discharge phenomenon. The present invention relates to a method for manufacturing an antistatic cathode ray tube.

[Prior Art] With the recent increase in the size of color cathode ray tubes and the improvement in luminance performance and focus performance, the voltage applied to the phosphor screen of the cathode ray tube, that is, the accelerating voltage of the electron beam has increased. For example, in the 21-inch class conventional color cathode ray tube, the high voltage applied to the phosphor screen was about 25 to 27 KV, but according to the recent 30-inch or more color cathode ray tube,
A high voltage of 30 to 34 KV is applied to the fluorescent screen. As a result, the outer surface of the face plate part of the color cathode-ray tube is charged, especially when the power of the TV set is turned on and off. As a result, the luminance performance of the color cathode ray tube is deteriorated. In addition, there is also a disadvantage that a discharge phenomenon occurs when a viewer approaches the outer surface of the charged face plate portion, and the viewer is uncomfortable.

Fig. 6 is a graph showing changes in the surface potential of the face plate portion of the cathode ray tube. (L) in the figure is a curve of the surface potential when the power is ON, and (L1) is the power OFF. 3 is a change curve of the surface potential at the time.

In order to eliminate the charge-up phenomenon on the outer surface of the face plate portion of the cathode ray tube, a smooth transparent conductive film is formed on the outer surface of the face plate portion of the cathode ray tube so that the charge is released to the ground. Antistatic-treated cathode ray tubes have been used recently.

FIG. 5 is a diagram for explaining the principle of antistatic treatment of the above-described antistatic cathode ray tube. In FIG. 5, (6) is a neck portion, which has an electron gun (not shown) built therein.
(7) is a deflection yoke, (4) is a face plate part,
(5) is a high-voltage button, the deflection yoke (7) is a deflection power source via the lead wire (7a), the electron gun is a drive power source via the lead wire (6a), and the high-voltage button (5) is Each is connected to a high voltage power supply via a lead wire (5a).

In the cathode ray tube having the above-mentioned structure, the deflection yoke (7) electromagnetically deflects the electron beam emitted from the electron gun built in the neck portion (6) from the outside of the cathode ray tube, and the face electrode through the high pressure button (). A high voltage is applied to the fluorescent surface provided on the inner surface of the plate portion (4). As a result, the electron beam is accelerated, and the energy thereof is used to excite and emit light on the phosphor screen to take out a light output. This face plate part (4)
As described above, the potential of the outer surface of the face plate portion (4) changes due to the influence of the high voltage applied to the fluorescent surface of the inner surface of the plate, and adverse effects such as adhesion of dust occur.

Therefore, as a measure for eliminating such an adverse effect,
As shown in the figure, a smooth transparent conductive film (11) is formed on the outer surface of the face plate portion (4), and this transparent conductive film (11) is grounded so that the charge is always released to the ground. The antistatic treatment type cathode ray tube ( 3 ) prevented the charge gap.

By the way, in this antistatic treatment type cathode ray tube ( 3 ), in order to drop the transparent conductive film (11) formed on the outer surface of the face plate portion (4) to the ground, as shown in FIG. A conductive tape (12) is provided between the metal explosion-proof band (8) wound around the side wall of the plate (4) and the transparent conductive film (11). As a result, the metal explosion-proof band (8) is joined to the ground (10A) by the ground wire (10) attached to the mounting ear (9), so that the transparent conductive film (11) should be dropped to the ground. Is easily possible.

Curves (M) and (M1) in FIG. 6 are the ones when the power supply of the antistatic treatment type cathode ray tube ( 3 ) in which the smooth transparent conductive film (11) is formed on the outer surface of the face plate part is turned on and off. This shows the potential change on the outer surface of the face plate portion, and it can be seen that the charge gap is significantly smaller than before.

Since the smooth transparent conductive film (11) formed on the surface of the face plate (4) is required to have a certain degree of hardness and adhesiveness, a silica (SiO ₂ ) based film is generally formed.

Conventionally, as a method of forming the smooth transparent conductive film (11) of silica type, an alcohol solution of Si (silicon) alkoxide having a functional group such as -OH group and -OR group is used for a face plate portion of a cathode ray tube. A method has been employed in which the outer surface of (4) is uniformly and evenly coated by a spin coating method or the like, and then baked at a relatively low temperature, for example, 100 ° C. or lower.

A smooth transparent conductive film (1
1) is porous and has silanol groups (≡Si-O
Since it has H), it can adsorb moisture in the air and reduce the surface resistance. However, when such a conventional smooth transparent conductive film (11) is baked at a high temperature, the silanol group --OH disappears, and the moisture taken in the pores also disappears. As a result, the predetermined conductivity cannot be obtained. Therefore, low temperature baking is essential and the strength of the film is not very strong. Further, if it is used for a long time in a dry environment, the water content in the porosity will be lost, and the surface resistance value will increase with time. When water is removed from this porous medium, it is difficult to get into it.

As described above, the conventional smooth transparent conductive film (11) has major drawbacks in terms of film strength and stability of resistance value over time. Moreover, in order to improve such a defect,
Although it has been attempted to bond a metal atom such as Zr (zirconium) to the alkoxide structure in the coating solution to impart conductivity, it is not possible to expect a significant improvement.

As a fundamental solution to these problems, the above Si (silicon)
Fine particles of SnO ₂ (oxide) or In ₂ O ₃ (indium oxide) are mixed and dispersed in an alcohol solution of alkoxide as a conductive filler, and a small amount of P (phosphorus) or Sb ( Face plate part (4) of the cathode ray tube using a coating liquid containing antimony)
As in the conventional method, apply it evenly and evenly on the outer surface of the spin coat method, etc.
By performing the baking treatment at (00 ° C.), the film strength can be increased and a smooth transparent conductive film (11) whose resistance value does not change with time under any environment can be obtained.

As described above, SiO ₂ (silica) obtained by dispersing a conductive filler in an alcohol solution of Si (silicon) alkoxide.
It has been found that the film of the system has the above-mentioned advantages, but has the following major problems in terms of characteristics.

That is, fine particles of SnO ₂ (tin oxide) were added to the alcohol solution of Si (silicon) accoxide to 1.
An antistatic cathode ray tube was prepared by applying 5% by weight of the coating liquid to the outer surface of the face plate part (4) of the cathode ray tube by spin coating and baking it at 150 ° C for 30 minutes. I made it. And various experiments were conducted on this antistatic cathode ray tube, the surface resistance value was 5 × 10 ⁶ Ω · cm, and the film strength was 9H or more in pencil hardness.
In addition, the surface resistance value under dry conditions did not fluctuate, and the charge cap when the TV set was turned on and off was similar to the characteristics shown in (M) and (M1) of FIG. However, it was found that when the surface of the transparent conductive film (11), which is smooth in the operating state of the television set, is touched while moving the back of the hand or the like, a slight vibration feeling is felt in the hand. Such a feeling of vibration is not a shock such as a charger, but is a problem peculiar to the conductive filler-dispersed silica (SiO ₂ ) -based film that does not flicker in the conventional cathode ray tube. Feel something is wrong.

As a result of various studies on the cause of such a feeling of vibration, when applying an alcohol solution of Si (silicon) alkoxide in which conductive filler particles are dispersed by a wet process such as spin coating, When the amount of filler particles increases, the particles abruptly agglomerate during drying, and when viewed microscopically, as shown in FIG. 4, the conductive filler particles (2) are composed of SiO ₂ (Syria) matrix ( It was found in 1) that a chain-like network structure was formed. In a macroscopic view, the smooth transparent conductive film (11) in such a state does not cause problems due to charge jumps because the charge escapes to the ground, but microscopically, after turning on the power of the TV set, , The potential distribution on the smooth transparent conductive film (11) surface becomes non-uniform in a mesh shape even after sufficient time passes,
If you touch the surface of the back of your hand while moving it, you will feel a vibration as if your back were shaking.

Further, the application of the coating liquid by the above-mentioned spin coating method or the like was performed after the explosion-proof treatment of fastening the side wall of the face plate portion (4) of the cathode ray tube with a metal band was completed.

FIG. 7A is a schematic manufacturing process drawing of a conventional cathode ray tube. In FIG. 7, (20) is a panel mask assembling process,
(21) panel mask / pair bake process, (22) coating / AL process, (23) panel bake process, (24) frit sealing process, (25) gun sealing process, (26) Is an exhaust process, (27) is a seasoning aging process, (28) is a characteristic test process, (29) is an explosion-proof treatment process, and (30) is a shipping process. Each of these processes (20) to (30) is described above. A cathode ray tube is manufactured by carrying out in the order described.

Further, FIG. 7 (B) is a schematic manufacturing process diagram of a conventional antistatic treatment type cathode ray tube. As is apparent from the figure, in the case of manufacturing a conventional antistatic treatment type cathode ray tube, Among the conventional cathode ray tube manufacturing processes shown in FIG. 1A, an antistatic treatment process (31) is newly added between the explosion-proof treatment process (29) and the shipping process (30). The antistatic treatment step (31) includes two steps, a coating liquid application step (31A) by a spin coating method and a baking treatment step (31B). Since other steps are the same as those in FIG. 7A, the same reference numerals are given and the description thereof is omitted.

[Problems to be Solved by the Invention] As described above, according to the conventional antistatic cathode ray tube having the smooth transparent conductive film, in order to improve the strength of the conductive film and prevent the surface resistance value from changing with time. When the conductive filler particles are added and the film is applied by a wet process such as spin coating, the conductive filler particles form a chain network structure in the matrix of SiO2 (silica), and as a result,
While moving the back of the hand etc. while the TV set is ON,
When touching the surface of the transparent conductive film, there is a problem that the back of the hand feels like vibration and a feeling of strangeness.

Further, in the case of the above-described conventional method for manufacturing an antistatic-type cathode ray tube, there are the following two problems in terms of manufacturing process and film performance.

That is, as a problem in the manufacturing process, it is necessary to newly install the furnace for the baking treatment of the coating film. That is,
Considering holding at 150 ° C for 30 minutes as a baking condition, it will be slightly different depending on the capacity of the production line and the size of the cathode ray tube to be produced.
It requires a furnace length of 100 m, and adding such a furnace to the production line is very disadvantageous in terms of space.

Also, as a problem in terms of film performance, when a coating film is formed on a completed cathode ray tube and baking is performed, the baking temperature must be 200 ° C or less in terms of reliability and life of the cathode ray tube. That is. In the case of the conventional antistatic cathode ray tube, the film strength of the transparent conductive film is not at a sufficiently satisfactory level. In the case of a SiO ₂ (silica) -based transparent conductive film, the higher the baking temperature, the higher the film strength.
If baked at a temperature of ℃ or above, it will be almost as strong as glass. However, the film strength was not sufficient due to the above-mentioned constraints. Furthermore, the energy loss due to the heat treatment of the completed cathode ray tube was great.

The present invention has been made to solve the above-mentioned problems, and even if the user touches the surface of the face plate portion while moving the back of the hand while the television set is operating, the user can almost feel the feeling of vibration and discomfort. The purpose is to obtain an antistatic treatment type cathode ray tube.

[Means for Solving the Problems] The antistatic-type cathode-ray tube according to the present invention is a coating liquid in which a conductive filler is dispersed in an alcohol solution of a silicon alkoxide having a —OH group or a —OR group as a functional group. An antistatic cathode ray tube in which a smooth transparent conductive film is formed on the face plate portion by applying it to the outer surface of the plate portion and baking the outer surface of the face plate portion after the above baking treatment. The surface resistance value Rs of is set in the range of 5.0 × 10 ⁹ Ω · cm <Rs ≦ 1.0 × 10 ¹¹ Ω · cm.

[Operation] According to the present invention, the surface resistance value Rs of the smooth transparent conductive film formed on the outer surface of the face plate portion after the baking process is 5.0 × 10 ⁹ Ω · cm <Rs ≦ 1.0 × 10 By setting it in the range of ¹¹ Ω · cm, the amount of conductive filler particles dispersed in the SiO2 (silica) matrix is controlled, and as a result, the conductive filler particles are very evenly dispersed and Since the potential distribution on the outer surface of the plate can be kept uniform, even if the face plate portion of the cathode ray tube is touched while moving the back of the hand during operation of the television set, there is almost no feeling of vibration.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an enlarged structure of a transparent conductive film in an antistatic cathode ray tube according to an embodiment of the present invention.
In the figure, (1) is a matrix of SiO ₂ (silica), fine particles of SnO ₂ (tin oxide) and In ₂ are added to an alcohol solution of Si (silicon) alkoxide having a —OH group, a —OR group, etc. as a functional group. A conductive filler composed of fine particles of O ₃ (indium oxide) is mixed and dispersed. (2) is the conductive filler particles in the matrix (1).

The SiO ₂ (silica) -based coating liquid described above is applied to the face plate portion (4) of the cathode ray tube by a wet process such as a spin coating method, dried, and then baked to give () in FIG. A smooth transparent electrode film as shown in 11) is formed. In this case, the surface resistance value (Rs) after the above baking treatment is 5.0 × 10 ⁷ Ω ・ cm ≤ Rs ≤ 1.0 × 10 ¹¹ Ω ・ cm
Set to.

Next, the transparent conductive film (11) having the structure shown in FIG.
An experiment conducted by the inventors of the present application and a result of the anti-conduction type cathode ray tube having the above will be described.

As mentioned above, when the amount of conductive filler particles such as SnO ₂ (tin oxide) dispersed in the alcohol solution of Si (silicon) alkoxide becomes large, when the coating liquid is applied by a wet process such as spin coating, it is dried. At times, the conductive filler particles rapidly aggregate to form a chain-like network structure as shown in FIG. 4, which is not preferable. For this reason, we experimentally produced an antistatic cathode ray tube using a coating liquid in which the amount of conductive filler particles in an alcohol solution of Si (silicon) alkoxide was changed variously. The cathode ray tube was actually mounted on a TV set and operated, and a vibration sensation evaluation test was performed.

FIG. 2 is a diagram showing the results of the above-described vibration sensation evaluation test. Since there is a correlation between the amount of conductive filler particles added and the surface resistance of the smooth transparent conductive film after baking,
In FIG. 2, the added amount of the conductive filler particles is shown as the surface resistance value of the smooth transparent conductive film after the baking treatment. Further, as shown in the same figure, the vibration feeling is evaluated in 6 levels from 0 to 5, and the vibration feeling 0 is a level that is not felt at all.
The vibration sensation 5 is a level at which the user feels very strong. As a result of this mounting evaluation, it was found that if the vibration feeling was 2.5 or less, there was practically no problem. In this case, the surface resistance of the smooth transparent conductive film after baking was 5.0 × 10 ⁷ Ω · cm. From a microscopic view of this smooth transparent conductive film, as shown in FIG. 1 (A), the conductive filler particles (2) have SiO ₂
It is uniformly dispersed in the matrix (1) of (silica), and there is almost no chain network structure. Further, when the amount of the conductive filler particles (2) is decreased, the surface resistance value becomes 1 × 10 ¹¹ Ω · cm and the vibration feeling becomes almost zero. However, when the added amount of the conductive filler particles (2) is further reduced, as shown in FIG. 1 (B), the conductive filler particles (2) in the matrix (1) of SiO ₂ (silica) are added. Are sparsely present, and the surface resistance value becomes uneven both at each place on the face plate and each product, which is not preferable in terms of the antistatic treatment effect.

Based on the above experimental results, a coating solution in which conductive filler particles are dispersed in an alcohol solution of Si (silicon) alkoxydol is applied to the face plate part of the cathode ray tube by a wet process such as spin coating, dried, and then baked. Surface resistance value (Rs) after baking in an antistatic cathode ray tube that is treated to form a smooth transparent conductive film
It has been found that by controlling the value of P in the range of 5.0 × 10 ⁷ Ω · cm ≦ Rs ≦ 1.0 × 10 ¹¹ Ω · cm, it is very preferable for all properties.

FIG. 3 is a schematic manufacturing process drawing of the antistatic treatment type cathode ray tube according to the present invention. In FIG.
The difference with the conventional manufacturing process diagram shown in is that the antistatic treatment process (3) is provided between the explosion-proof treatment process (29) and the shipping process (30).
1) is not provided, and only the coating liquid application step (31A) of the antistatic treatment step is set before the panel baking step (23) which is one of the heat treatment steps unique to the cathode ray tube manufacturing process. The panel baking process (23) also serves as the baking process of the antistatic process. Since other steps are the same as those in FIG. 7 (B),
The same reference numerals are given and their description is omitted.

In addition to the panel baking process (23) described above, the heat treatment process that also serves as the baking process of the antistatic treatment process includes the frit sealing process (24) and the exhaust process (2).
It may be 6). Each of these steps is from 380 ℃
Since this is a heat treatment process in which treatment is carried out at an extremely high temperature of 450 ° C., as shown by the phantom line in FIG. 3, the coating liquid application process (31A) is performed before these processes (24) and (28). It is possible to set and set these steps (24) and (26) to also serve as the baking processing step of the antistatic processing steps.

Also, the panel mask / pair bake step (21) has a high processing temperature and can also serve as the baking processing step of the antistatic processing step. However, this panel mask / pair bake step (21) immediately follows the chemical processing step. This is not preferable because the transparent conductive film (11) is likely to be damaged by alkali or acid in the coating / AL process (22) and the transparent conductive film (11) is easily scratched due to many material handling processes. .

Furthermore, since the gas sealing step (25) and the exhaust step (26) are continuous steps, the coating liquid application step (31)
As shown by the phantom line in FIG. 3, A) may be set in the preceding stage of the gun sealing step (25) so that the baking process of the antistatic treatment step is performed in the exhaust step (26).

Incidentally, in the above-mentioned examples, SnO ₂ (tin oxide) or In ₂ O was added to the alcohol solution of Si (silicon) alkoxide as the coating liquid.
We used a dispersion of conductive filler particles such as ₃ (indium oxide).
Even when the same coating liquid in which other metal atom such as (zirconium) is bonded is used, the same effect as above can be obtained.

[Advantages of the Invention] As described above, according to the present invention, the conductive filler particles are uniformly dispersed by setting the amount of the conductive filler particles dispersed in the matrix of SiO ₂ (silica) within a certain range. Therefore, even if the surface of the face plate is touched while moving the back of the hand while the TV set is in operation, there is no feeling of vibration or discomfort. Further, it is possible to obtain a high quality antistatic cathode ray tube in which the strength of the transparent conductive film is high and the surface resistance value is stable.

[Brief description of drawings]

FIG. 1 is a diagram showing an enlarged structure of a transparent conductive film in an antistatic cathode ray tube according to an embodiment of the present invention, and FIG. 2 is a diagram showing the surface resistance value and the outer surface of the face plate portion when touched. The figure which shows the result of the evaluation test with a feeling of vibration, FIG. 3 is a schematic manufacturing process drawing of the antistatic-treatment type cathode ray tube of this invention,
FIG. 4 is a diagram showing an enlarged structure of a transparent conductive film in a conventional antistatic treatment type cathode ray tube, FIG. 5 is a diagram for explaining the antistatic principle of the antistatic treatment type cathode ray tube, and FIG. 6 is a cathode ray face. A graph showing the potential change on the outer surface of the plate part,
7 (A) and 7 (B) are schematic structural process diagrams of a conventional cathode ray tube and an antistatic treatment type cathode ray tube. (1) …… Mixed body of SiO ₂ (silica), (2) …… Particles of conductive filler, ( 3 ) …… Antistatic treatment type cathode ray tube,
(4) …… face plate part, (111) …… smooth transparent conductive film, (23) …… panel baking process, (24) ……
Frit sealing process, (25) …… Gun sealing process, (26)…
… Exhaust process, (29) …… Explosion proof process, (31A) …… Coating liquid application process. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A baking treatment is performed by applying a coating liquid, in which a conductive filler is dispersed in an alcohol solution of a silicon alkoxide having a —OH group or a —OR group as a functional group, to the outer surface of a face plate portion. In the antistatic treatment type cathode ray tube in which a smooth transparent conductive film is formed on the face plate portion, the surface resistance value R _S of the outer surface of the face plate portion after the baking treatment is 5.0 × 10 ⁹ Ω An antistatic cathode ray tube characterized by being set in the range of cm <R _S ≦ 1.0 × 10 ¹¹ Ω · cm.