JPH01252901A - Electrostatic field preventing filter - Google Patents

Abstract

PURPOSE:To obtain the title filter with excellent electrostatic field preventing function and easy to manufacture by including a dielectric film layer having the resisting value of 10<5>-10<13>OMEGA/sq. in a multi-layer antireflection film. CONSTITUTION:The resisting value >=10<5>OMEGA/sq. of the dielectric film layer is sufficient for attaining only the electrostatic field preventing function, and when the value exceeds 10<13>OMEGA/sq., the function is not recognized. The substance of the dielectric film layer with the electrostatic field preventing function as mentioned above and the excellent film thickness controlling property and uniform distribution etc. at the time of forming the film is exemplified by TiO2, Ta2O5 or Al2O3, etc. The preferable film formation of the filter is constituted of a middle refractive index layer as 1st layers 1a, 1b and a high refractive index layer composed of TiO2, etc. as 2nd layers 2a, 2b and a low refractive index layer as 3rd layers 3a, 3b, in case of the antireflection film being constituted of 3 layers. When the filter is mounted on a CRT, etc., an electron is led to the dielectric film layer through a grounding, whereby a negative potential generates, and a positive potential at the front of the CRT, etc. disappears. As the result that the potential is zero, the electrostatic field prevention can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrostatic field prevention filter. The electrostatic field prevention filter of the present invention is preferably used as a filter for CRT displays used in computer terminals, word processors, etc.

[Prior Art and Problems Therewith] With the spread of computers and the like in recent years, CRT displays and the like are increasingly being used for long periods of time.

As a result of long-term use of CRT displays, etc.,
First, eye strain can be mentioned. Eye strain is caused by external light reflected from the surface of a CRT display or the like, flickering of the screen of a CRT display, or the like. To prevent these, a neutral-density glass substrate (transmittance 3) is used.
A filter having an anti-reflection coating on a glass substrate (such as 0% to 70%) has been mounted on the front surface of a CRT display, etc., and has been effective.

Another problem caused by long-term use of CRT displays and the like is damage to the operator's skin, cornea, etc. caused by electromagnetic waves. Therefore, as a countermeasure,
Conventionally, a conductive film with a low resistance value of 103Ω/□ or less, such as ITO (indium oxide/tin oxide) or tin oxide, is formed on a substrate alone or as part of a multilayer antireflection film. Electromagnetic waves are removed by taking out the ground from the conductive film.

The conductive film made of the above-mentioned ITo1 tin oxide is very effective in preventing electromagnetic waves, but its refractive index is much higher than that of the substrate.For example, ITO, which is a conductive film with the lowest refractive index, Even in this case, the refractive index is 1.9 and the reflectance of this film is 15%, so if the substrate is coated with only ITO, it cannot be used as a filter.

Further, when a conductive film such as ITO or tin oxide is coated as a part of a multilayer antireflection film by vacuum evaporation, the following problems arise.

■ It is difficult to precisely control these II conductive films and optical films, which adversely affects the properties of the antireflection film.

■ It is difficult to uniformly coat a large area substrate with these S dielectric films.

(2) There are concerns about the stability of the S conductivity of these S conductive films, and it has been pointed out that the characteristics deteriorate in particular with respect to moisture.

(2) Since the conductive film material is limited to ITO, ItC tin, etc., there is little freedom in designing the film structure.

■ It is difficult to control the refractive index of these S dielectric films.

Therefore, I as an anti-reflection film has difficulties in production and performance.
It has been desired to develop a new filter that does not have the above-mentioned drawbacks in place of conventional filters equipped with conductive films such as TO or tin oxide.

[Means for solving the problem] According to recent research on human health, it is clear that damage to the human skin, cornea, etc. caused by CRT displays, etc. is caused by electrostatic fields rather than by the electromagnetic waves mentioned above. It is becoming.

Therefore, as a result of searching for a material that can prevent the electrostatic field, the present inventor found that the resistance value, which has the disadvantage of being used as an anti-reflection film, is 1.
It has been shown that static electric fields can be prevented when a dielectric film with a resistance value in the range of 10 to 1013 Ω/□, which does not have the above-mentioned drawbacks, is provided as an anti-reflection 1) film instead of a II electrical installation with a resistance of 03 Ω/□ or less. I found it.

Therefore, the present invention provides a grounded filter in which a multilayer antireflection film is formed on the base, in which the multilayer antireflection film is
The present invention provides an electrostatic field prevention filter comprising at least one m dielectric film layer having a resistance value of 0 to 1013 Ω/□.

The mechanism of electrostatic field prevention of the electrostatic field prevention filter of the present invention will be described as follows. In other words, an electrostatic field is generated by a high positive voltage applied to the front surface of a CRT display, etc., and the CRT is attracted by the electrostatic field.
Electrons are connected through the ground to a dielectric film layer with a resistance value of 105 to 1013 Ω/□ on a filter installed in front of a display, etc., creating a negative potential, resulting in C
The positive potential on the front surface of the RT display, etc. is canceled and becomes zero potential, achieving prevention of static electric fields.

In the present invention, the at least one dielectric film layer is
Its resistance value is limited to 10 to 1013 Ω/□. The reason for this is that in order to only prevent static electric fields, a resistance value of 105Ω/□ or more is sufficient, as will be clear from Examples 1 to 5 below, and if it exceeds 1013Ω/□, This is because, as is clear from the comparative example, the electrostatic field preventing effect is no longer recognized.

In the filter of the present invention, the material for the dielectric film layer that has an electrostatic field prevention function and has excellent film thickness controllability, uniformity of distribution, etc. when producing a multilayer antireflection film is T t.
O, T a2 o5. A I 203 and mixtures containing one or more of these substances can be used, and by using these substances, it is possible to solve problems such as film thickness control and film thickness control, which were conventional problems when using conductive films such as ITO and tin chloride. It has become possible to significantly improve the degree of freedom in the design of the structure and the durability of the membrane material.

The preferred layer structure of the electrostatic field prevention filter of the present invention having a multilayer antireflection film is as follows.

(1) When the multilayer antireflection film consists of two layers, the first layer is a high refractive index layer and the second layer is a low refractive index layer from the substrate toward the outside.

12) When the multilayer antireflection coating consists of three layers, the first
The layer is an intermediate refractive index layer, the second layer is a high refractive index layer, and the third layer is a low refractive index layer, and the refractive index of the third layer (low refractive index layer) is lower than the refractive index of the substrate.

(3) When the multilayer antireflection coating consists of four layers, the first
The layer is a low refractive index layer, the second layer is an intermediate refractive index layer, the third layer is a high refractive index layer, and the fourth layer is a low refractive index layer. refractive index of layer).

is lower than the refractive index of the substrate.

In the above-mentioned layer structure of the anti-reflection film, at least one layer thereof is constituted by a dielectric film layer made of a substance as exemplified above and having a resistance value of 10 to 10 13 Ω/□.

Note that as a film forming method, a vacuum lid method, a solution method, a sputtering method, etc. are employed.

In the filter of the present invention, a glass substrate such as soda lime glass or neutral density glass, or a plus book substrate such as acrylic resin is used as the substrate. In particular, neutral density glass provided with an antireflection film is particularly effective in preventing eye strain.

Further, it is preferable that the ground is connected to the dielectric film layer having a resistance value of 10 to 1013 Ω/□, but the upper layer provided on the dielectric film layer is, for example, an optical g! If the thickness is as thin as λ/4, it is also possible to connect the ground from the upper layer. This is because even though the upper layer is an insulator, it is thin and can conduct electricity when a high electric field is applied.

[Examples] The present invention will be described in detail below, but the present invention is not limited to these Examples.

Example 1 First, an example of manufacturing an electrostatic field prevention filter of this example having a layer structure as shown in FIG. 1 will be described.

A three-layer antireflection film 1a, Ib; 2a, 2b;
and 3a and 3b were formed by a vacuum steaming method under the following conditions.

That is, cerium fluoride is applied to the surface of the glass substrate 4.
The optical film thickness (
The first layer is made of cerium fluoride and has a wavelength of 130 nm (nd) of 130 nm.
A layer (intermediate refractive index layer) 1a was first formed.

Next, a second layer (high refractive index layer) 2a made of titanium oxide with an optical thickness (Od) of 260 rv is formed by vacuum evaporation at a vacuum degree of 1 x 10' Torr (oxygen introduced). I let it happen. The resistance value of this second layer is 3X
It was 105Ω/□.

Furthermore, by vacuum evaporation with the degree of vacuum set to I x 10-4 Torr (oxygen introduced), the optical film thickness (nd)
A third layer (low refractive index layer) 3a made of silicon dioxide having a thickness of 1'30 nm was formed.

Next, on the back side of the glass substrate 4, in the same manner as above, a first layer (intermediate refractive index layer) 1bX a second layer (high refractive index layer) 2b,
A third layer (low refractive index layer) 3b was formed. 1 of these
For ilb, 2b, and 3b, the vapor deposition material, optical film thickness, etc. were the same as those of the above layers 1a, 2a, and 3a, respectively.

Thereafter, the ground 5 was removed from the second layer 2a to obtain the electrostatic field prevention filter of this example.

Next, the antistatic ability of the filter of this example was measured as follows. In other words, a computer (NEC P
An electrostatic field measuring device (Stachiron-M, Shishido Electrostatic Co., Ltd.) was installed 60 m in front of the CRT display (NEC PC-KD853) connected to the C-980/VX41), and the power source of the CRT display was turned on. As a result, the static voltage was 15KV. Next, a similar test was conducted by installing the filter of this example, which was grounded at a distance of 30 am from the measuring device, between the CRT display and the measuring device. The results are shown in FIG.

According to FIG. 2, when the filter of this example was used, the static voltage became O in about 30 seconds, and the antistatic ability was very excellent.

Example 2 A three-layer antireflection film was formed on the same soda lime glass substrate used in Example 1 by a dipping method (immersion coating method).

(1) Preparation of low refractive index coating agent While stirring a mixed solution of 20.8 g (0,1101) of tetraethoxysilane and 90 g (1,96 io1) of ethanol at room temperature, 5.4 g (0.3 mol) of water, 0.1
2 g of N hydrochloric acid and 90 g (1,96101) of ethanol were added dropwise. Next, the mixture was stirred at room temperature for 4 hours to react, and left to mature for 12 hours. This was filtered through a filter with an opening of 0.5 μl to obtain a low refractive index coating agent.

(2) Creation of high refractive index coating agent Tetraisopropoxy titanium 2 (1 (0,0671 ol
) and 70 g (1.2 mol) of ethanol were stirred at room temperature while adding 2 g (0.11 sol) of water, o, 1
1 g of N salt M and ethanol 709 (1,2101) were added dropwise. Next, the mixture was stirred at room temperature for 4 hours to react, and left to mature for 12 hours.

This was filtered through a filter with an opening of 0.5 μl to obtain a high refractive index coating agent.

(3) Preparation of intermediate refractive index coating agent 6.6 g of tetramer of tetraethoxysilane (0.00
9 mol), tetraisopropoxy titanium 8.5 g
(0,03sol) and ethanol 90g (1,96s
ol) was stirred at room temperature while adding 2 g of water (0,
11101), 1g of 011N hydrochloric acid, 90g of ethanol (
1,96 sol) was added dropwise.

Next, the mixture was stirred at V temperature for 4 hours to react, and left to mature for 12 hours. This was filtered through a filter with an opening of 0.5 μl to obtain an intermediate refractive index coating agent.

(4) Formation of 3-layer anti-reflection film After cleaning and drying the substrate with a super wave cleaner, first coat the intermediate refractive index coating agent prepared in (3) above with 45%
Dip coating was carried out at a speed of cm/1n. This was dried at 200° C. for 10 minutes to form a coating film for an intermediate refractive index layer. Similarly, the high refractive index coating agent prepared in the above (2) and the low refractive index coating agent prepared in the above (1) were dip coated at a speed of 2Qcm/1n and 12cm/sin, respectively, to form a high refractive index layer. After forming the coating film for the coating and the coating film for the low refractive index layer, they were baked at 500° C. for 60 minutes.

The intermediate refractive index layer, which is the first layer of the three-layer antireflection film obtained after firing, is a film with an optical thickness (nd) of 120 nm made of a mixture of silicon dioxide and titanium oxide, and the second layer is a film with an optical thickness (nd) of 120 nm. A certain high refractive index layer has an optical thickness (nd
) It was a film of 240 nm and a resistance value of 2×10 12 Ω/□, and the third layer, a low refractive index layer, was made of silicon dioxide and had an optical thickness (nd) of 120 nm.

Next, the second layer was grounded to obtain the filter of this example.

The electrostatic field prevention ability of the filter of this example was measured in the same manner as in Example 1. As a result, as shown in FIG. 2, almost the same electrostatic field prevention effect as in Example 1 was observed.

Example 3 Similarly to Example 1, a four-layer antireflection film was formed on both the front and back surfaces of a soda lime glass substrate by vacuum evaporation. The film-forming conditions for each layer and the optical thickness (nd) of each layer after film-forming are shown below.

First layer (low refractive index layer) Vapor deposition material Vacuum degree during magnesium fluoride vapor deposition 2 X 10' Torr (no oxygen introduced) Optical film thickness (nd) 130 nm Second layer (intermediate refractive index layer) Vapor deposition material Oxidation True 9 degrees during aluminum evaporation I Torr (Oxygen introduced) Optical film thickness (nd) 26Or+n+ Fourth layer (low refractive index layer) Vapor deposition material Magnesium fluoride Vacuum degree 2 X 10'Torr (No M element introduced) Optical film fj (nd) 130 nm Next, the above The filter of this example was obtained by connecting the ground to the second layer of the filter.

The obtained filter of this example also had the same electrostatic field prevention effect as the filter of Example 1, as shown in FIG.

Example 4 As in Example 1, a two-layer antireflection film was formed on both the front and back surfaces of a soda lime glass substrate using the vacuum evaporation method.

The film formation regulations for each layer and the optical film thickness (nd) value of each layer after film formation are shown below.

First layer (high refractive index layer) Vapor deposition material Tantalum oxide Vacuum degree I ) Vapor deposition material Magnesium fluoride vacuum a 2 X 10-'' Torr (no introduction of M element) Optical film thickness (nd) 130 layers 11 Next, earthing was taken from the first cap to obtain the filter of this example.

As shown in FIG. 2, the obtained filter of this example also had the same electrostatic field prevention effect as the filter of actual flow example 1.

Example 5 As in Example 1, a three-layer antireflection film was formed on both the front and back surfaces of a soda lime glass substrate by vacuum evaporation.

Film forming strip material for each layer and optical film thickness (ncl) of each layer after film formation
The values of are shown below.

First layer (intermediate refractive index B) Vapor deposition material Cerium fluoride true 9 degrees 2 X 10-5 Torr (no oxygen introduced) Optical film thickness (nd) 130 nllll Second layer (high refractive index layer) Vapor deposition material Titanium oxide Zirconium oxide mixture Vacuum level I 12.times.10.sup.-5 Torr (no lil element introduced) Optical film thickness (nd) 13 Qnm Next, grounding was taken from the second Tatsumi to obtain the filter of this example. .

The obtained filter of this example also had the same electrostatic field prevention effect as the filter of Example 1, as shown in FIG.

Comparative Example Except that the first, second, and third layers were each made of a vapor-deposited film of a substance having a resistance value exceeding the tenth limit specified in the present invention.
As in Example 1, a three-layer antireflection film was formed on both the front and back surfaces of a soda lime glass substrate by vacuum evaporation. The values of the film-forming strip material of each layer and the optical film thickness (nd) after film-forming are as follows.

First layer (intermediate refractive index layer) Vapor deposition material Cerium fluoride Vacuum degree 2 X 10 ”” Torr (no oxygen introduced) Optical 11U thickness (nd) 130 layer m Second layer (high refractive index layer) Vapor deposition material Oxidation Zirconium vacuum degree I X 10-' Torr (oxygen introduced) Optical film thickness (nd) 260 layer m Third layer (low refractive index layer) Vapor deposition material Magnesium fluoride Vacuum degree 2 X 10-5 Torr (no oxygen introduced) Optical Film thickness (nd): 130 layers m Next, the second layer was grounded to obtain a filter of this comparative example.

As shown in Figure 2, the obtained filter of this comparative example has a slightly lower static voltage than the filter without a filter, but unlike the filters of Examples 1 to 5, no static voltage damping effect was observed. I couldn't.

[Effect of the invention] At least 1lF of the multilayer antireflection film provided on the substrate
The electrostatic field prevention filter of the present invention, which is composed of a dielectric film layer having a resistance value of 10 to 1013 Ω/□, has an excellent static electric field prevention function.

Further, the dielectric 111 layer having the above-mentioned resistance value can be selected from a variety of dielectric materials, and it is possible to control the film thickness, improve the degree of freedom in film installation, and improve the durability of the film material.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the layer structure of the electrostatic field prevention filter of Example 1, and FIG. 2 is a graph showing the electrostatic field prevention function of the electrostatic field prevention filters of Examples 1 to 5. 1a, 1b...first layer (intermediate refractive index layer) 2a, 2b
...Second layer (high refractive index layer) 3a, 3b...Third layer (low refractive index layer) 4...Soda lime glass substrate 5...Ground

Claims (1)

[Claims] 1. In a grounded filter in which a multilayer antireflection film is formed on a substrate, the multilayer antireflection film has a thickness of 10^5 to 10
An electrostatic field prevention filter comprising at least one dielectric film layer having a resistance value of ^1^3Ω/□.