JP2000011902A - Optical filter for display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of a filter and occurrence of abnormality caused by the deterioration due to heat generation of a screen during lighting for long time by installing a filter having a heat resistance value within a specified region on a display screen. SOLUTION: Thermal resistance (m2.K/W) of an optical filter 10 provided on a display screen 21 of a plasma display panel 20 is set in the range of 0.005 to 0.1. The optical filter 10 is obtained by forming transparent high polymer such as acryl or polycarbonate, where near infrared ray absorbing pigment is mixed like a plate or reflecting near-infrared rays on the screen side of the transparent plate-like formed body to be intercepted, thereby forming a silver thin film effective for electromagnetic wave interception. Both methods may be used concurrently. A silver thin film may be formed on a transparent high polymer film as need, and then stuck to a plate-like formed body by a pressure-sensitive adhesive material. The sheet resistance value of the silver thin film is 10 Θ/square or less, and the transmissivity for near-infrared rays or visible light rays is controlled by regulating the quantity of near-infrared ray absorbing pigment mixed and the thickness of the silver thin film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical filter installed on a display screen.
More specifically, the present invention relates to an optical filter that suppresses occurrence of abnormalities such as discoloration caused by heat generation of a display. This is particularly effective when the display is a plasma display panel that generates a large amount of heat.

[0002]

2. Description of the Related Art In recent years, as society has become more sophisticated, optoelectronics-related components and equipment have remarkably advanced.
Among them, displays for displaying images have been remarkably popularized for computer monitor devices in addition to conventional television devices. Among them, market demands for larger and thinner displays are increasing.

[0003] Recently, a plasma display panel (PDP) has attracted attention as a display that can be made large and thin. However, the plasma display panel emits strong near-infrared rays in principle. The near-infrared rays cause malfunctions of cordless telephones, infrared remote controllers, and the like. The optical filter has a wavelength of 80 emitted from the display screen.
It is used to block near-infrared rays of 0 nm to 1000 nm, and is installed on a display screen. Therefore, the light transmittance of the optical filter is 800 nm to 10 nm.
Low for near infrared of 00 nm, wavelength is 380 nm
It is desirable to be high for visible light of up to 800 nm. Further, in the visible light region, not only high transmittance but also optical characteristics that do not impair the image of the display such as color tone are required.

[0004] As means for blocking near infrared rays,
(1) A material that absorbs near-infrared rays is mixed into a material constituting a filter. (2) Coating the surface of the filter with a material that reflects near infrared rays. Are roughly divided into two types. Examples of the material that absorbs near-infrared light include dithiol complex compounds, which are commercially available as near-infrared-absorbing dyes. Silver is known as a material that reflects near infrared rays. In addition, it is known that a plasma display panel emits a strong electromagnetic wave outside the device. Electromagnetic waves are known to cause damage to instruments, and it has recently been reported that electromagnetic waves may also cause damage to the human body. For this reason, the emission of electromagnetic waves has been legally regulated. For example, at present in Japan, VCCI (Volunta
ry Control Council for In
terreference by data processes
sing equipment electronic
Office machine)
In the United States, the FCC (Federal Communication)
There is a product regulation by the National Communications Commission. In recent years, optical filters having a function of blocking electromagnetic waves emitted from a screen have been developed. Filters having a function of blocking electromagnetic waves can be roughly classified into two types. One is a so-called metal mesh type in which metal is thinly arranged in a grid pattern on the entire surface of a substrate. Although this has an excellent electromagnetic wave blocking ability, it is not very preferable for use as a display filter because of poor transparency and a moire image. The other is called a transparent thin film type,
The transparent conductive thin film is disposed over the entire surface.
As a material of the thin film, a material having a low resistivity is preferable, and silver and gold are mentioned as suitable materials. Above all, silver also has near-infrared reflectivity, so that an optical filter having a near-infrared blocking function and an electromagnetic wave blocking function can be obtained by disposing a silver thin film designed to have an appropriate thickness. Actually, an optical filter with an electromagnetic wave blocking function in which optical characteristics in the visible light region are controlled by laminating a silver thin film and a thin film having an appropriate refractive index has been developed. This type does not generate a moire image unlike the metal mesh type, and does not reduce the image performance of the display.

A transparent conductive thin film type optical filter is often obtained by laminating a transparent conductive thin film on a polymer molded substrate or a glass substrate. The advantage of this method of laminating films is that thin films can be formed continuously while winding the base film around a roll, which is suitable for mass production. Further, an optical film having a reflectance reducing function, an antiglare function or a toning function is often combined with a transparent conductive film and bonded.

[0006]

When an optical filter having an infrared blocking ability is installed on a display screen of a plasma display panel to complete a display, and this is turned on and left for a long time, the optical filter changes color and the color tone is changed. A changing problem has occurred. This impairs the long-term reliability of the plasma display, and there has been a strong demand for a solution.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, the heat generated in the plasma display panel is transmitted to the optical filter, and a part of the optical filter is removed. It was determined that abnormalities occurred as a result of heating. The optical filter is heated at a part of the portion near the display, and an abnormality occurs at that portion. The present inventors have found that by controlling the thermal resistance of the optical filter, it is possible to suppress the occurrence of the abnormality, and reached the present invention.

That is, according to the present invention, (1) the thermal resistance is 0.0
(2) an optical filter for a display, which is not less than 05 (m ² · K / W) and not more than 0.1 (m ² · K / W) and is installed on the screen of the display.
(1) The optical filter for a display according to (1), wherein a transparent plate-shaped molded body and a transparent thin film are laminated, (3) the transparent thin film has a sheet resistance of 10 (Ω / □) or less. (2) The optical filter for a display according to (2), wherein (4) a polymer film coated with a transparent thin film and a transparent plate-like molded body are bonded together (2). (5) The optical filter for a display according to any one of (1) to (4), wherein the display is a plasma display panel. is there.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The optical filter according to the present invention has a thermal resistance of 0.005 (m ² · K / W) or more and 0.1 or more.
(M ² · K / W) or less. The thermal resistance must be limited to this range in order to prevent the deterioration of the optical filter due to heat generation on the screen when the display is continuously turned on. This is particularly effective when used as an optical filter of a plasma display that generates a large amount of heat from a display screen. The display screen of the plasma display reaches about 80 ° C. to 90 ° C. during continuous lighting, and heats the optical filter installed on the screen.
That is, the plasma display panel itself becomes a heat source for heating the optical filter. At the time of continuous lighting of the plasma display panel, the optical filter is heated in a portion where the distance from the plasma display panel is short. If the thermal resistance of the optical filter is large, heat is not stored but stored. The heat storage deteriorates the near-infrared absorbing dye and the silver thin film used for blocking near-infrared rays, and causes problems such as discoloration. This problem can be solved by setting the thermal resistance of the optical filter to the upper limit or less.

The lower limit of the thermal resistance of the optical filter is 0.0
05 (m ² · K / W). If the thermal resistance is less than 0.005 (m ² · K / W), the heat generated in the display will reach the outside through the optical filter and the heat dissipation will be improved, but even the outside of the optical filter that humans may touch. It gets hot. Therefore, the thermal resistance of the optical filter is 0.005 (m ² · K /
W) or more and 0.1 (m ² · K / W) or less.

The present invention will be described with reference to the accompanying drawings. FIG.
FIG. 1 shows an example of an embodiment of the present invention, and is a view of a state where an optical filter is installed on a screen of a display as viewed from a cross section. In FIG. 1, the optical filter 10
It is installed on the display screen 21 of the plasma display panel 20. When the plasma display panel is continuously turned on, the display screen reaches 80 ° C. to 90 ° C. and is transmitted to the display screen side 11 of the optical filter. If the thermal resistance of the optical filter is large, heat is stored in this portion, and deterioration occurs. Conversely, if the thermal resistance of the optical filter is low, even the outside 12 of the optical filter becomes hot, and this portion is dangerous because a person may directly touch it. 2
Reference numeral 5 denotes a fastener for installing the optical filter on the display screen of the display.

The shape of the optical filter is preferably a plate shape so as to be placed on the screen of the display. Further, a material having sufficient mechanical strength, light weight and hard to be broken is preferable. As a material to be used as a base material, polymer materials such as polymethyl methacrylate and acrylic or polycarbonate can be suitably used. In the case of manufacturing an optical filter that absorbs and blocks near infrared rays, a near infrared ray absorbing dye may be mixed into a material serving as a base material, and molded into a planar shape. The near-infrared transmittance can be controlled by the amount of the near-infrared absorbing dye mixed. When an optical filter that reflects and blocks near-infrared rays is manufactured, a silver thin film may be formed on the surface of a substrate formed in a plate shape. Also in this case, a material such as polymethyl methacrylate or polycarbonate is suitable as the base material. The control of near-infrared transmittance and the transmittance of visible light can be controlled by the thickness of the silver thin film.

An optical filter may be manufactured by combining two methods, that is, a method of absorbing a near-infrared ray by mixing a near-infrared ray absorbing agent and a method of forming a thin film that reflects a near-infrared ray. In that case, a silver thin film may be formed on the surface of the substrate formed by mixing a near infrared absorbing agent.

If a silver thin film is used to block near-infrared rays, it can be used for blocking electromagnetic waves, and is most suitable for use as an optical filter of a plasma display that emits electromagnetic waves from a screen. in this case,
When an optical filter is installed on the display screen, an electromagnetic wave radiated from the display screen can be attenuated by electrically connecting the silver thin film to the display ground. At this time, the sheet resistance of the silver thin film was 10
Ω / □ or less is preferable. If the sheet resistance value is high, the electromagnetic wave blocking ability is reduced, and the sheet cannot be used as an electromagnetic wave blocking film.
When the screen size is increased, the sheet resistance value must be further reduced. When used for a plasma display panel having a 42-inch screen, 2 Ω is used.
/ □ or less is preferred. Since the sheet resistance is determined by the thickness of the silver thin film, the thickness may be controlled within a range that does not impair the optical characteristics.

Silver is the most suitable as a thin film material constituting the optical filter of the present invention in that it reflects near-infrared rays and has excellent conductivity, but has the disadvantage of low durability under high humidity. Having. In order to remedy this drawback, silver may be doped with a noble metal such as gold, palladium, platinum or copper in an amount of 1 to 50% by weight. Although the optical characteristics of silver are slightly changed by doping with a noble metal, the durability under high humidity can be dramatically improved.

It is also known that wavelength dispersion of visible light transmittance can be controlled by laminating materials having different refractive indexes from silver in an appropriate configuration. As a material having a different refractive index, a material having a refractive index of 1.4 or more with respect to a light having a wavelength of 550 nm, a small absorption in a visible light region, and a wavelength of 400 nm to 7
A material having a transmittance of 60% or more for a light beam of 00 nm is preferable. Specific examples include oxides such as titanium oxide, indium oxide, tin oxide, silicon oxide, antimony oxide, aluminum oxide, bismuth oxide, and zinc oxide. Among these, indium oxide doped with tin oxide, zinc oxide doped with aluminum oxide, and tin oxide doped with antimony oxide are optimal materials because they have a high refractive index of 2.0 or more and also have conductivity. . A / b / c / b, A / b / c / b / c / b, and A / b are listed as lamination configurations suitable for controlling chromatic dispersion in the visible light region.
/ C / b / c / b / c / b, A / b / c / b / c / b /
c / b / c / b, A / b / c / b / c / b / c / b / c
/ B / c / b. Here, A represents a substrate, b represents an oxide thin film, and c represents a silver thin film.

The silver thin film or the oxide thin film may be formed by a conventionally well-known method such as a vacuum evaporation method or a sputtering method. In the vacuum deposition method, a desired material is used as a deposition source, and a metal thin film can be easily formed by performing heating deposition by resistance heating, electron beam heating, or the like. In the case of using a sputtering method, a metal thin film can be formed by using a desired material as a target, using an inert gas such as argon or neon as a sputtering gas, and using a DC sputtering method or a high-frequency sputtering method. it can. When an oxide thin film is formed, oxygen may be mixed in a sputtering gas and formed while reacting with oxygen. In order to increase the deposition rate, a DC magnetron sputtering method or a high-frequency magnetron sputtering method is often used.

The substrate may be a plate-like molded body, and an acrylic plate or a polycarbonate plate can be used as the substrate. A hard coat layer is often provided on a plate-shaped molded body for reasons such as increasing the surface hardness or adhesion. As the hard coat layer material, an acrylate resin or a methacrylate resin is often used, but is not particularly limited. The method of forming the hard coat layer is as follows.
An ultraviolet curing method or a polymerization transfer method is often used, but is not particularly limited thereto. In the polymerization transfer method, a target material is limited to a cell cast polymerization material such as a methacrylate resin, but a hard plate layer can be formed with very high productivity by a continuous plate making method. For this reason, the formation of the methacrylate resin layer by the polymerization transfer method is the most suitably used method of forming a hard coat layer.

Since the vapor deposition method and the sputtering method for forming a silver thin film require a vacuum vessel, it is sometimes difficult to directly form a uniform silver thin film over the entire surface of a large-sized plate-like molded product. is there. In such a case, a silver thin film may be formed on a rollable polymer film using a roll-to-roll method, and this may be bonded to a plate-like molded body. The material of the polymer film is not particularly limited as long as it has transparency. Specifically, polyimide, polysulfone (PSF), polyethersulfone (PE)
S), polyethylene terephthalate (PET), polymethylene methacrylate (PMMA), polycarbonate (PC), polyetheretherketone (PEEK),
Polypropylene (PP), triacetyl cellulose (T
AC) and the like. Among them, polyethylene terephthalate (PET) and triacetyl cellulose (TA)
C) is particularly preferably used. FIG. 2 is a view of the configuration of the optical filter manufactured as described above, as viewed from a cross-sectional direction. A silver thin film 30 was formed on the surface of a polymer film 31 and bonded to a plate-shaped molded body 33 with an adhesive 32 to complete an optical filter. Since the polymer film can be wound into a roll, it is suitable for mass processing of silver thin film formation.

The adhesive used for bonding the plate-like molded product and the film with a transparent conductive thin film is preferably as transparent as possible. Examples of usable pressure-sensitive adhesives include an acrylic pressure-sensitive adhesive, a silicon-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a polyvinyl butyral pressure-sensitive adhesive (PVB), and an ethylene-vinyl acetate-based pressure-sensitive adhesive (EVA). Above all, acrylic pressure-sensitive adhesives are particularly preferably used because of their excellent transparency and heat resistance. The same pressure-sensitive adhesive can also be used when laminating a film or sheet dielectric to an optical filter.

The form of the adhesive is roughly divided into a sheet-like material and a liquid-like material. The sheet-shaped pressure-sensitive adhesive is usually of a pressure-sensitive type, and is laminated by laminating each member after lamination. The liquid adhesive is cured by leaving it at room temperature or heating after application and bonding. Examples of the method of applying the adhesive include a bar coating method, a reverse coating method, a gravure coating method, and a roll coating method. Is selected in consideration of the type, viscosity, application amount, etc. There is no particular limitation on the thickness of the adhesive layer,
To 50 μm, preferably 1 to 30 μm. After bonding using the adhesive, pressurize and heat to remove the bubbles that entered when bonding, to dissolve in the adhesive, and to improve the adhesion between the members. Curing is preferably performed under conditions. At this time, the pressure condition is generally about several atmospheres to about 20 atmospheres, and the heating condition is generally room temperature or higher and 80 ° C. or lower although it depends on the heat resistance of each member.

In the present invention, there is no particular limitation on the bonding method using an adhesive. Normally, an adhesive is stuck to a polymer film, and a film covered with a release film is prepared in advance in a roll, and the release film is peeled off while the polymer molding film is being pulled out from the roll. Then, it is pasted on the polymer molded body substrate, and it is pasted while pressing with a roll. The same applies to a case where the film is laminated on the laminated film.

The thermal resistance of the optical filter can be controlled by changing the thickness and the number of sheets to be bonded. The thermal resistance R (m ² · K / W) of the plate-like sample can be calculated from the thermal conductivity λ (W / (m · K)) of the material and the thickness d (m) according to the equation (1).

R (m ² · K / W) = d (m) / λ (W / (m · K)) (1) A simple method for changing the thermal resistance is to control the thickness d (m). However, setting the thickness maintains sufficient mechanical strength,
The weight must not be too heavy. When it is difficult to set the thermal resistance to a desired range only by changing the thickness, the thermal resistance can be changed by laminating a polymer film. Since different materials are bonded, the thermal conductivity λ of (1) (W / (m · K))
Can be changed.

The thermal resistance is measured by a method based on any one of a direct plate method, a flat plate comparison method, a flat plate heat flow meter method, and a protected hot plate heat flow meter method described in ASTM C-518 and JIS A-1412. Can be measured. Devices that can easily measure thermal resistance by a method based on these methods are commercially available. The layer structure and the state of each layer of the optical filter produced by the above method can be examined by using a cross-sectional optical microscope measurement, a scanning electron microscope (SEM) measurement, and a transmission electron microscope measurement (TEM).

[0026]

Next, the present invention will be described in detail with reference to examples. (Example 1) Polyethylene terephthalate pellets 12
03 (manufactured by Unitika Ltd.) was mixed with 0.3% by weight of a diol complex represented by the following formula (1) [formula 1].
Melted at 280 ° C and 100μm thick by extruder
Was prepared, and then this film was biaxially stretched to prepare a dye film having a thickness of 50 μm. This dye film was bonded to a 3 mm-thick poly (methyl methacrylate) plate (manufactured by Mitsubishi Rayon Co., Ltd.) via an acrylic adhesive to complete an optical filter for a display. The size was set to be fit on the screen of a 42-inch wide display.

[0027]

Embedded image

Example 2 A target indium was applied to one surface of a colorless and transparent 50 μm thick polyethylene terephthalate film, and indium oxide was used as a sputtering gas by using an argon / oxygen mixed gas (total pressure: 266 mPa, oxygen partial pressure: 80 mPa). The indium oxide thin film was 40 nm, the silver thin film was 10 nm, the indium oxide thin film was 70 nm, the silver thin film was 10 nm, and the silver thin film was formed by magnetron DC sputtering using a thin film as a target, silver as a target, and argon gas (total pressure of 266 mPa) as a sputtering gas. Indium thin film 40 nm, silver thin film 10 nm, indium oxide thin film 70
nm, a silver thin film 10 nm, an indium oxide thin film 40 nm, a silver thin film 10 nm, and an indium oxide thin film 40 nm in this order to form a laminated film. An optical filter for display was completed by bonding a surface of the laminated film opposite to the surface on which the laminated thin film was formed and a 3 mm-thick polymethyl methacrylate plate (manufactured by Mitsubishi Rayon Co., Ltd.) via an acrylic adhesive. Was.

(Example 3) The dye film prepared in Example 1 was applied to one surface of a polymethyl methacrylate plate having a thickness of 3 mm, and the laminated film prepared in Example 2 was applied to the other surface with an acrylic adhesive. Using the agent, an optical filter for a bonded display was completed.

Example 4 An optical filter for display was completed in the same manner as in Example 3 except that the thickness of the polymethyl methacrylate plate was changed to 7 mm.

Example 5 An optical filter for a display was completed in the same manner as in Example 3 except that the thickness of the polymethyl methacrylate plate was changed to 1.5 mm.

Comparative Example 1 An optical filter for a display was completed in the same manner as in Example 3 except that the thickness of the polymethyl methacrylate plate was changed to 1 mm.

Comparative Example 2 An optical filter for display was completed in the same manner as in Example 3 except that the polymethyl methacrylate plate having a thickness of 7 mm was changed to a polycarbonate plate having a thickness of 7 mm.

The thermal resistance of the optical filter for a display manufactured by the above method is measured by a thermal conductivity measuring device (manufactured by Eiko Seiki Co., Ltd., model number: H) in accordance with ASTM C-518.
C-072) using a heat flow meter. The high-temperature plate side temperature was 40 ° C. and the low-temperature plate side temperature was 10 ° C.

Next, the optical filter for the display was set to 4
The two-inch wide plasma display panel was mounted on the screen with its surfaces in contact with each other, and the display was turned on and allowed to stand. After 500 hours from the lighting, the display optical filter was removed from the plasma display screen, and the presence or absence of abnormality such as discoloration was visually examined. The results are summarized in [Table 1].

[0036]

[Table 1] Table 1 shows that the display optical filter of the present invention is:
It can be seen that there is no appearance failure even when used on a screen of a plasma display for a long time.

[0037]

According to the present invention, when the display is lit for a long time, the deterioration of the optical filter installed on the display screen is suppressed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of an embodiment of the present invention.

FIG. 2 is a sectional view showing an example of a display optical filter of the present invention.

DESCRIPTION OF SYMBOLS 10 Optical filter for display of the present invention 11 Display screen side of optical filter for display 12 Outside of optical filter for display 20 Display 21 Display screen of display 25 Fastener for attaching optical filter for display 30 Silver thin film DESCRIPTION OF SYMBOLS 31 Polymer film 32 Adhesive 33 Plate-shaped molded object

Continuation of front page (72) Inventor Shin Fukuda 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa F-term (reference) 4F100 AA17B AB24B AK01C AK25A AK25G AK42C AR00A EH66B EJ38C GB41 GB90 JG04B JM01B JN01B JN01B

Claims (5)

[Claims] A heat resistance is not less than 0.005 (m ² · K / W) and not more than 0.1 (m ² · K / W) and is installed on a screen of a display. Optical filter for display. 2. The optical filter for a display according to claim 1, wherein a transparent plate-like molded body and a transparent thin film are laminated. 3. The sheet resistance of a transparent thin film is 10 (Ω /
□) The optical filter for a display according to claim 2, wherein: 4. The optical device for a display according to claim 2, wherein a polymer film coated with a transparent thin film and a transparent plate-like molded body are bonded to each other. filter. 5. The optical filter for a display according to claim 1, wherein the display is a plasma display panel.