JPS6258202A - Filter for crt - Google Patents

Abstract

PURPOSE:To adjust contrast and to prevent the electrification of a filter surface by forming a conductive absorption film on the rear face of a base material thereby improving an antireflection effect and decreasing the flickering of a CRT screen. CONSTITUTION:An antireflection film 3 is formed on the front face of the base material 1 and the conductive absorption film 2 is formed on the rear face of the material 1. The film 2 consists of a metal simple substance such as nickel, cobalt, molybdenum, iron or chromium or a mixture composed of metal such as the alloy thereof or cermet, etc. and ceramics of which the film is formed on the material 1 by using a thin film forming method such as vapor deposition or sputtering method. The film 2 has electrical conductivity. The film 2 is preferably formed to such a thickness at which the reflectivity of the incident light from the base material side is minimized, the light transmittance of the filter for CRT after formation of the film 2 is 30-80% and the surface resistance thereof is 10<3>-10<10>(OMEGA/square).

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a CrtT filter used in computer terminals, word processors, and the like.

"Prior Art" In recent years, office automation has become widespread, and as a result, eye fatigue caused by viewing CRTs for display for long periods of time has begun to be seen as a problem.

Such eye fatigue is caused by indoor light reflected off the surface of the CRT and incident on the eyes, flickering of the CRT screen, and
This is largely due to the high contrast of the screen, so C.
CR attached near the surface of the RT to reduce eye fatigue
Various T filters have been devised.

As the CRT filter described above, the one shown in FIG. 2 is generally used at present.

The CRT filter shown in FIG. 2A has a base material 1 made of plastic such as acrylic resin or glass.
An anti-reflection film 3 consisting of a single layer or multiple layers is formed on one side of the CRT, and the surface on which the anti-reflection film 3 is not formed is usually used facing the CRT.

The CRT filter shown in FIG. 1B is obtained by applying matte processing to the surface of the filter shown in A on which the antireflection film 3 is not formed.

The CRT filter shown in FIG. 1C has antireflection films 3 and 3 as shown in A above formed on both sides of the base material 1 to enhance the antireflection effect.

[Problems to be Solved by the Invention] However, it has been found that the above-mentioned conventional CRT filter has the following problems in actual use.

First, in the CRT filter shown in FIG. 2A, although the reflection of indoor light on the surface 8 on which the antireflection film 3 of the filter is formed is suppressed, the indoor light that has passed through the antireflection film 3 is The light is reflected on the back surface 9 where the light is not formed, passes through the antireflection film 3 again, and enters the eyes of the CRT user. Therefore, there has been a complaint that this CRT filter does not have a sufficient antireflection effect, and therefore does not have a sufficient effect on preventing eye fatigue.

In the CRT filter shown in FIG. 2B, one side is made of a matte surface 7, so that incident indoor light is diffusely reflected there, thereby enhancing the antireflection effect of the filter.

However, in this filter, CR1 passes through the matte surface 7.
Since the screen must be viewed, there was a problem in that the resolution of the CR1 screen was reduced.

Furthermore, when the above CRT filters A, B, and C are attached to a CRT and used, the filter surface becomes charged due to static electricity generated by the CRT, and dust in the air is attracted to the filter surface. It had the disadvantage of getting dirty easily.

Incidentally, it is known that eye fatigue caused by viewing a CRT is not only caused by reflection of indoor light, but also by flickering and high contrast of the CRT screen itself. It is known that the flicker and contrast of this CR1 screen can be improved to some extent by reducing transmitted light with a filter. However, all of the above CRT filters A, B, and C are insufficiently effective in reducing transmitted light, and CR1
Screen flickering and contrast could not be sufficiently improved.

This invention was made in view of the above circumstances, and is
It is an object of the present invention to provide a CRT filter that reduces eye fatigue when using an RT and has a high antistatic effect.

13 = "Means for solving the problem" The CRT filter of the present invention has a coating film formed on the surface of the base material for preventing reflection, and a conductive absorption film formed on the back surface of the base material. It is something.

"Function" In the CRT filter of the present invention, the conductive absorption film formed on the back surface of the filter enhances the anti-reflection effect, reduces the flickering of the CR1 screen, adjusts the contrast, and prevents the filter surface from being charged. To prevent.

Embodiment FIG. 1 shows a first embodiment of a CRT filter of the present invention, and in this figure, reference numeral 1 indicates a base material. An antireflection film 3 is formed on the surface of this base material l,
Further, a conductive absorption film 2 is formed on the back surface of the base material 1.

The base material 1 is molded from plastic such as acrylic resin, polycarbonate resin (PC), or polystyrene resin (PS), or glass.

The above conductive absorption film 2 is made of simple metals such as nickel, cobalt, molybdenum, iron, chromium, etc., or alloys thereof,
Alternatively, a mixture of metal and ceramics such as cermet is formed on the base material 1 using a thin film forming method such as a vacuum evaporation method or a sputtering method, and this conductive absorption film 2 has conductivity. It is something that you have.

The thickness of the conductive absorption film 2 is such that the reflectance for incident light from the base material side is the minimum, and the light transmittance of the CRT filter after forming the conductive absorption film 2 is 30% to 30%. 80%
It is desirable to form the filter to a thickness such that its surface resistance is 10" to 1G (Ω/hole). If the above light transmittance is greater than 80%, this CRT filter is When using CR1, sufficient flicker prevention effect and contrast optimization effect cannot be obtained, and 30
If it is smaller than %, the CR1 screen will become too dark and CR
One screen becomes difficult to see. In addition, the above surface resistance is 10
” (Ω/mouth), the antistatic effect will not be sufficient.

In this embodiment, the above-mentioned anti-reflection film 3 is a three-layer anti-reflection film consisting of coating layers 4, 5, and 6, and these coating layers 4, 5, and 6 are all formed using a vacuum evaporation method, a sputtering method, or the like. These are sequentially formed on a base material l using a thin film formation method.

The first coating layer 4 is formed using a conventionally used coating agent such as alumina or itria, and its optical thickness is
is assumed to be 1/4λ. Here, is the refractive index of the layer, d is the thickness of the layer, and λ is the center wavelength (the same applies hereinafter). In addition,
When the base material I is made of a material that expands and contracts with temperature changes, such as plastic, it is desirable that the coating layer 4 be made of yttoria. In such a case,
It is possible to improve the adhesion between the antireflection film 3 and the base material 1, and to prevent cracks from forming in the antireflection film 3.

The second coating layer 5 is formed using a high refractive index coating agent, such as zirconium dioxide, which has a different refractive index from the first coating layer 4,
Its optical thickness is I/2λ.

The third coating layer 6 is formed using silicon dioxide or magnesium fluoride, which is relatively strong among coating agents and has excellent abrasion resistance, and has an optical thickness of 1. /4λ.

In the CRT filter having such a configuration, since the conductive absorption film 2 is formed on the back surface of the filter, it is possible to reduce the reflection of room light incident on the filter back surface (experimental example described later). (Reference) ``Therefore, it is possible to reduce eye fatigue caused by indoor light reflection when using a CRT.

In addition, this CRT filter has the above-mentioned conductive absorption film 2.
Therefore, when this filter is attached to a CRT and used, it has the effect of reducing eye fatigue caused by the flickering and high contrast of the CRT screen.

Furthermore, since this CRT filter has a conductive absorption film 2 formed on the back surface of the filter, by grounding this conductive absorption film 2, the filter surface is prevented from being charged due to static electricity generated by the CRT. can. Therefore, with this CRT filter, it is possible to prevent problems such as the filter surface becoming dirty due to static electricity attracting dust in the air, unlike conventional CRT filters.

Note that the CRT filter of the present invention is not limited to the above-mentioned embodiments, and various other modifications are possible. For example, in the above experimental example, the antireflection film 3 is composed of three coating layers, but the antireflection film may be a single layer or a multilayer other than three layers, as necessary.

"Experimental Example" Next, an experimental example of the present invention will be given to clarify the effects of the present invention.

(Experiment Example 1) Glass substrate (BK-7, refractive index 1.52°, thickness 1.3511) 1/4 λ alumina, 1/2 λ zirconium dioxide, 1/4 magnesium fluoride on the surface
1X1 (I'Tor
Coating was performed by a vapor deposition method using an electron beam at r. On the other hand, the back surface was coated with chromium as a conductive absorbing film by the above vapor deposition method at I x 10-' Torr so as to have a film thickness that minimized the reflectance (approximately 3 Onm).

(Comparative Example 1) l (The same antireflection film as in Experimental Example 1 was formed on the same glass substrate as in Experimental Example 1, but no conductive absorption film was formed.

(Comparative Example 2) The same glass substrate as in Experimental Example 1 was used as is.

(Experiment example 2) Mitsubishi Rayon acrylic plate (refractive index 1
．． 52, thickness 2 II) alumina on the surface of 1/4λ
, zirconium dioxide to an optical thickness of 1/2λ, and magnesium fluoride to an optical thickness of 1/4λ.
The coating was performed by evaporation using an electron beam at 'Torr. On the other hand, on the back side of the acrylic plate, nickel was coated as a conductive absorption film with I
was coated by the above vapor deposition method.

(Comparative example 3) Mitsubishi Rayon acrylic plate (refractive index 1
．． 52, thickness 211131), the same conductive absorption film as in Experimental Example 2 was formed on the back surface.

(Comparative Example 4) The same antireflection film as in Experimental Example 2 was formed on the same acrylic substrate as in Experimental Example 2.

(Comparative Example 5) The same acrylic base material as in Experimental Example 2 was used as it was.

Experimental Examples 1 and 2 and Comparative Example 1 obtained as above
-5, the reflectance was measured in the range of 360 to 800 nm. The measuring instrument used was a self-recording spectrophotometer U-3400 manufactured by Hitachi, Ltd.

Among these, the results for those made of glass substrate are shown in the graph of FIG. In FIG. 3, the vertical axis indicates the reflectance (%) of the filter, the horizontal axis indicates the wavelength (nm), the symbol Jl indicates the experimental example 1, the symbol HI indicates the comparative example 1, and the symbol H2 indicates the comparative example 2.

As can be seen from this graph, Experimental Example 1, which has a conductive absorption film, has an excellent antireflection effect over the entire visible light range.

Further, the results of measuring the reflectance of the acrylic base material are shown in FIG. In Fig. 4, the vertical axis is the reflectance (%) of the filter, the horizontal axis is the wavelength (nm), and the symbol J2 is Experimental Example 2.
Code H3 is comparative example 3, code 1-14 is comparative example 4, code I
(5 indicates Comparative Example 5. It can also be seen from FIG. 4 that the antireflection effect of the conductive absorption film is remarkable in the entire visible light range.

Further, FIG. 5 shows the measured transmittance of Comparative Example 3 and Comparative Example 5. In this figure, the vertical axis indicates the transmittance (%) of the filter, the horizontal axis indicates the wavelength (nm), the symbol H3 indicates Comparative Example 3, and the symbol H5 indicates Comparative Example 5, respectively. The transmittance of the base material itself (Comparative Example 5) is 93%, but in Comparative Example 3 coated with Ni, the transmittance can be adjusted to 65%. Furthermore, as is clear from this figure, the spectral characteristics of the absorption film are flat over the entire visible light range, and the color balance of the CRT screen is not disturbed.

Next, in order to confirm the antistatic effect of the absorbing film, the half-life time of the charging voltage was measured using the coulometric decay method for Comparative Examples 3.4.5. The measuring device used was 5tatic Honestmeter from Soybean Shokai Co., Ltd., with an applied voltage of 8
Each sample was charged with kV and a current of 0.8 A, and the time required for the charged voltage to decrease to one half (half-life time) was measured.

The results are shown in the table below.

When a conductive absorption film is formed so as to be exposed from the surface,
It has a remarkable antistatic effect.

"Effects of the Invention" Since the CRT filter of the present invention has a conductive absorption film formed on the back surface of the anti-reflection filter, it is possible to reduce the reflection of room light incident on the CRT filter on the back surface of the filter. , it is possible to reduce flickering on a CRT screen, and therefore, when this filter is attached to a CRT and used, it is possible to reduce eye fatigue.

Furthermore, since this CRT filter has a conductive absorption film formed on the back of the filter, by grounding this conductive absorption film, the filter surface is prevented from being charged by static electricity generated by the CRT. This can prevent problems such as the filter surface becoming dirty due to static electricity attracting dust in the air.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first embodiment of a CRT filter of the present invention, and FIGS. 2A, B, and C are sectional views showing a conventional CRT filter. Further, FIGS. 3 and 4 are reflectance graphs showing the antireflection effect of experimental examples of the present invention, and FIG. 5 is a graph showing the transmittance characteristics of the absorbing film. l... Base material 2... Conductive absorption film 3... Anti-reflection film Fig. 2

Claims (1)

[Scope of Claims] A CRT filter having a coating film for anti-reflection formed on the surface of a base material, characterized in that a conductive absorption film is formed on the back surface of the base material.