JP2001159712A - Optical filter, display unit and front plate for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical filter excellent in reflecting characteristics and capable of adjusting transmittance in a wide range. SOLUTION: A two-layer antireflection film 3 comprising a light absorbing film 3a and a transparent dielectric film 3b is disposed on one face of a transparent substrate 2 and a colored adhesive layer 4 which transmits more light in a specified light-emitting area than light in another light-emitting are is disposed on the other face of the substrate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical filter capable of adjusting the amount of transmitted light having a specific wavelength, a display device having the optical filter, and a front panel for a display device.

[0002]

2. Description of the Related Art When an object is viewed through a transparent material, it is troublesome that reflected light is strong and the reflected image is clear. For example, in a spectacle lens, a reflected image called a ghost or a flare is generated, causing discomfort to the eyes. Or Also, there is a problem that the contents are not clear due to the light reflected on the glass surface by a looking glass or the like.

[0003] Conventionally, a method of coating a substance having a refractive index different from that of a substrate on a substrate by a vacuum deposition method or the like for preventing reflection has been performed. In this case, it is known that the selection of the thickness of the substance that coats the substrate is important in order to maximize the antireflection effect.

For example, in the case of a single-layer film, a substance having a lower refractive index than that of a base material is required to be １ ／ of the optical wavelength for the optical film thickness.
It is known that selecting an odd number or an odd multiple thereof gives a minimum reflectance, that is, a maximum transmittance.

Here, the optical film thickness is given by the product of the refractive index of the film forming material and the film thickness of the film. Further, it is possible to form a multilayer antireflection film. In this case, several proposals have been made regarding the selection of the film thickness (Optical Technology Contact Vol. 9, No. 8, page 17 (19)
71)).

In these antireflection films, the film forming material is mainly an inorganic oxide or an organic halide, and generally has both low reflectance and high transmittance in the visible light region.

On the panel surface of the display device, external light or illumination light may be reflected on the screen, making it difficult to see the image.
In order to suppress such surface reflection, an antireflection film is often provided on the display surface.

In a display device, it is necessary to adjust the transmittance of the display panel in a wide range (20 to 92%) in order to improve the contrast, for example, depending on the structure and application.
Generally, the display panel itself, for example, a CRT panel glass or a transmission type projector (rear projector)
In the acrylic front plate, the transmittance is adjusted by changing the transmittance of the panel base material itself.

[0009] However, the display panel has a role of maintaining the mechanical strength of the display device. Therefore, as an excellent transmittance adjusting method which is not restricted by such mechanical strength, there is a method of adjusting the transmittance by using a colored pressure-sensitive adhesive layer as disclosed in JP-A-10-187056. In particular, in a cathode ray tube, Japanese Patent Application Laid-Open No. 11-14337
As disclosed in Japanese Patent Laid-Open Publication No. 1 (1999), transmittance can be adjusted while improving the mechanical strength. Adjustment of these transmittances is performed by ND (Neutral) aiming at substantially the same transmittance at any wavelength in the visible light region.
Density) filter.

On the other hand, some color display devices include blue,
There is an object that expresses a color by combining three color light emitters that emit green light and red light. For example, in a combination of phosphors called P22 generally used in a color cathode ray tube, ZnS: Ag as a blue phosphor, ZnS: Cu, Al as a green phosphor, and Y ₂₀ as a red phosphor.
₂ S: Eu is used, and the peaks of the emission spectrum are at 450 nm, 532 nm, and 626 nm, respectively. These emission wavelengths and the respective emission spectrum shapes determine the color purity and the color reproduction area of the color cathode ray tube.

However, each of these phosphors has an emission spectrum unique to each material, and does not always emit light with the same luminance. Factors that affect the light emission luminance include the light emission efficiency, light emission area, light emission spectrum width, and electron beam energy density of the phosphor. When trying to display white by combining these three colors, there is an effect of the visibility of the eyes, and the imbalance of the injection energy applied to the phosphors of the three colors will inevitably occur.

For example, in a color cathode ray tube, the above P2
When displaying white with a color temperature of 9800 ° K in 2,
The cathode current ratio applied to the electron gun is about 1.0 for green, about 1.0 for blue, and about 1.2 for red. In other words, at the same cathode current, the luminance of the red light emission becomes the lowest, and in order to correct the red light emission, an extra 20% current is required only for the red color, and therefore the current capacity of the drive circuit has to be increased accordingly.

Further, among the antireflection films, there is a filter designed to incorporate a light absorption film, and there is a structure called a dark mirror, a selective absorption mirror, or an enhanced absorption mirror. A configuration called a dark mirror can be used as the antireflection film in the visible light region. The “Optical Thin Film User's Handbook” (P160, Nikkan Kogyo Shimbun) describes a two-layer dark mirror combining an absorption film and a dielectric film. Has been proposed.

[0014] On the other hand, Japanese Patent Application Laid-Open No. 9-156964 discloses that, in the configuration of the dark mirror, a metal nitride such as titanium, zirconium, and hafnium, that is, TiN, ZrN, and HfN, is used as a light absorbing film. It has been suggested that low reflection can be obtained in a wide range of light region.

Similarly, US Pat. No. 5,091,244 discloses a low-reflection and transmittance control in the visible light region by using a four- to six-layer antireflection film using a metal or metal nitride as a light absorbing film. At the same time.

Japanese Patent Application Laid-Open No. 64-79041 discloses a light absorbing film made of a metal, ie, Ti, Zr, M
o, Ni—Cr, transmittance 30 using Ni—Cr—Fe
-40% of the antireflection coating is illustrated.

Furthermore, in JP-A-1-198701, low reflection and 45.5 to 100 are provided by a six-layer antireflection film using metallic Ni as a third layer as a light absorbing film.
It is exemplified that the transmittance can be adjusted over a wide range.

[0018]

However, in the antireflection film including these light absorbing films, excellent low reflection characteristics, which cannot be obtained when a transparent dielectric is laminated, can be realized with a smaller number of layers, and the transmission is improved. Although the rate can be adjusted, the transmission characteristics of the light absorbing film are not always constant at all visible light wavelengths, and are not sufficient for a display device.

In particular, when a metal, a metal nitride or a metal oxide is used as the light absorbing film as disclosed in the above-mentioned patent publication, the long wavelength side of the visible light region (red side) ) Tends to lower the transmittance, and the color cathode ray tube has a problem that the red cathode current must be further increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its main object is to suppress deterioration of display quality while utilizing the excellent characteristics of an antireflection film including a light absorbing film, and to achieve a wide range. The present invention is to provide an optical filter capable of adjusting the transmittance by using the filter, a display device provided with the filter, and a front panel for the display device.

[0021]

The optical filter of the present invention is provided with a colored pressure-sensitive adhesive layer on one side of a transparent base material, and the colored pressure-sensitive adhesive layer has a specific light-emitting region among a plurality of light emission wavelengths. Has a characteristic of transmitting the light of the other than the light of the other light emitting region.

The display device of the present invention includes the optical filter having the above-described configuration.

A front panel for a display device according to the present invention is provided with the optical filter having the above-described configuration.

The optical filter of the present invention, the display device provided with the filter, and the front panel for the display device have a characteristic of transmitting light in a specific luminous region out of a plurality of luminous wavelengths more than light in other luminous regions. By providing the colored pressure-sensitive adhesive layer on one surface side of the transparent substrate, it is possible to adjust the transmittance of each emission wavelength transmitted through the optical filter by the selective transmission characteristics of the colored pressure-sensitive adhesive layer. This makes it possible to correct the imbalance of the light emission luminance of each phosphor due to, for example, a phosphor or the like, and to obtain a display device that is inexpensive and has excellent quality.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments.

FIG. 1 shows an embodiment of the optical filter according to the present invention. This optical filter 1 has at least one or more antireflection films (Ant) on one surface side of a transparent substrate 2.
An i-Reflection, AR film) 3 is formed, and a colored pressure-sensitive adhesive layer 4 is formed on the other surface, that is, on the surface opposite to the antireflection film 3 with the transparent substrate 2 interposed therebetween. The colored pressure-sensitive adhesive layer 4 has a characteristic of transmitting more light in a specific light emission region than light in other light emission regions among a plurality of light emission wavelengths in a display device. For example, among the three (blue, green, and red) emission wavelengths in a color display device, the color display device has a property of transmitting more light in one or two emission regions than light in other emission regions.

The transparent substrate 2 is not particularly limited as long as it has a degree of transparency (light transmission) that does not impair the display function of the display device. For example, a transparent glass plate, a plastic plate, A plastic film or the like can be used.

Among these, there are so-called glass substrates such as soda glass, lead glass, hard glass, quartz glass, liquid crystal glass, etc.
P. I-537, edited by The Chemical Society of Japan), silicate glass containing strontium (St) or barium (Ba) is preferably used for a cathode ray tube, and non-alkali glass is preferably used for a liquid crystal display device.

As the plastic base material, any material may be used as long as it is made of an organic polymer. Optical properties such as transparency, refractive index and dispersion, impact resistance, heat resistance, etc. From various characteristics such as durability,
(Meth) acrylic resins such as polymethyl methacrylate, copolymers of methyl methacrylate with other alkyl (meth) acrylates and vinyl monomers such as styrene; polycarbonates such as polycarbonate and diethylene glycol bisallyl carbonate (CR-39) Resins; thermosetting, such as homopolymers or copolymers of (brominated) bisphenol A type di (meth) acrylates, and polymers and copolymers of (brominated) bisphenol A mono (meth) acrylate urethane-modified monomers Polyester (especially polyethylene terephthalate, polyethylene naphthalate and unsaturated polyester, acrylonitrile-styrene copolymer, polyvinyl chloride, polyurethane, epoxy resin, etc.). It is also possible to use an aramid resin in consideration of heat resistance.

The plastic film substrate can be obtained by a method such as spreading these resins or diluting them in a solvent, forming a film, and drying the resin.
m to about 500 μm.

The surface of the plastic substrate as described above is disclosed in Japanese Patent Publication No. 50-28092 and Japanese Patent Publication No. 50-28.
No. 446, JP-B-51-24368, JP-A-52-112698 and JP-A-57-2735, even when coated with a coating material such as a hard coat. In addition, various properties such as adhesion, hardness, chemical resistance, durability, and dyeing property can be improved by this coating material present below the inorganic antireflection film made of an inorganic substance. The thickness of the hard coat is usually about 3 μm to 20 μm.

The anti-reflection film 3 is formed of at least one layer. For example, as shown in FIG. 1, it is preferable that the anti-reflection film 3 has a two-layer structure of a light absorption film 3a and a transparent dielectric film 3b. Thereby, a large anti-reflection effect can be obtained with a minimum film configuration, and the light transmittance can be easily adjusted in combination with the colored adhesive layer 4. However, it goes without saying that the antireflection film 3 may have a film configuration of three or more layers including a light absorption film.

The antireflection film 3 is formed by a vacuum evaporation method,
Typified by on-plating method, sputtering method, etc.
PVD (Physical Vapor De)
position) method. What is suitable for this PVD method
As for the quality, Au, Pt, Pb,
Fe, Fe-Ni, Ni-Cr, Ni-V, Al, A
g, Cr, Fe-Cr, Cu, Ti, Zr, Hf
Metal and its nitride and its oxide and its oxynitride
Available. Further, as the transparent dielectric film 3b, SiO 2 is used.
_Two, SiO, Si_ThreeN_Four, Al_TwoO_Three, ZrO_Two, TiO_Two,
Ta_TwoO_Five, TiO, Ti_TwoO_Three, HfO_Two, ZnO, In_Two
O_Three, In_TwoO_Three/ SnO_Two, SnO_Two, Y_TwoO _Three, Yb
_TwoO_Three, Sb_TwoO_Three, MgO, MgF_Two, CeO_TwoSuch as inorganic
Oxides are preferably applied.

In the anti-reflection film 3, there is disclosed in
A method of inserting a layer (oxidation barrier layer) for preventing the light absorbing film 3a from being oxidized, such as that disclosed in JP-A-165001 and JP-A-9-156964, can also be preferably applied. In this case, various metals and metal nitrides, Si ₃ N ₄ , AlN, and the like can be used as the oxidation barrier layer. In addition, since this oxidation barrier layer is an optically unnecessary layer, it is preferable to have a thickness of 20 nm or less in order not to deteriorate the antireflection characteristics.

Further, when the base material is plastic, in order to improve the adhesion between the transparent base material 2 and the antireflection film 3, US Pat.
A method of forming an extremely thin metal oxide and sulfide as the first layer (adhesive layer) of the antireflection film 3 as disclosed in JP-A-81121 can also be preferably applied.

When the light absorbing film 3a is formed of a metal film, the light absorbing film 3a also functions as a conductive film, and functions as an electromagnetic field shield for avoiding an influence on a human body in a display device such as a display for a computer. , And also has a screen antistatic function.

As the pressure-sensitive adhesive which is the main component of the colored pressure-sensitive adhesive layer 4, any material can be used as long as it can be adhered only by applying pressure at room temperature for a short time without using water, solvent, heat or the like. For example, natural rubber, IR, SBR, NBR
Various adhesives such as rubber, acrylic, and silicone can be used. An acrylic pressure-sensitive adhesive for a permanent adhesive having a high degree of cross-linking is suitable as the pressure-sensitive adhesive, since the pressure-sensitive adhesive does not re-peel after being attached to the display device. For example, an acrylic pressure-sensitive adhesive excellent in blister resistance, such as that disclosed in JP-A-10-279900, can be preferably used. In addition, an adhesive that functions as an adhesive after adhesion may be used.

In the present invention, the colorant is mixed with the pressure-sensitive adhesive to form the pressure-sensitive adhesive colorant layer 4, and the light transmittance is adjusted. Examples of the colorant include dyes and pigments such as carbon black.
It is preferable to use an inorganic pigment or an organic pigment from the viewpoint of durability and the like.

As the colorant, two or more dyes or pigments having selective permeability can be mixed.

The transmittance of each emission wavelength to be transmitted can be changed depending on the type of the dye or the pigment and the mixing ratio thereof, and the colored pressure-sensitive adhesive layer 4 can have a so-called selective transmission characteristic.

Light transmittance of colored adhesive layer 4 and antireflection film 3
Since the product of the light transmittances of the filters substantially determines the light transmittance of the filter, the anti-reflection film 3 has a desired selective transmission characteristic.
And the light transmittance of the colored pressure-sensitive adhesive layer 4 are considered.

Further, by mixing a plurality of types of dyes or pigments as described above, the colored pressure-sensitive adhesive layer 4 has an area (valley) between a plurality of emission wavelength peaks.
A transmittance characteristic lower than the transmittance at two adjacent emission wavelength peaks can be provided.

For example, as shown by a broken line in FIG. 2, in the region between the blue emission wavelength peak (450 nm) and the green emission wavelength peak (532 nm), two adjacent (blue and green) emission wavelength peaks are present. In the region between the green emission wavelength peak and the red emission wavelength peak (626 nm).
The colored pressure-sensitive adhesive layer 4 can have a so-called selective absorption characteristic having a transmittance characteristic lower than the transmittance of one of the emission wavelength peaks (green and red).

The optical filter 1 of the present invention is configured as an ND filter that corrects the variation in transmittance of the absorbing film due to the wavelength of visible light and makes the transmittance more constant at any wavelength in the visible light region. Can be.

The optical filter 1 of the present invention can be configured as a filter whose transmittance can be selectively adjusted according to the emission wavelength. This selectively permeable filter lowers the overall transmittance to improve contrast.
It can also have a D filter function.

The optical filter 1 of the present invention has an antireflection property and can selectively adjust the transmittance of each of the emitted wavelengths to be transmitted in a wide range, so that the colored pressure-sensitive adhesive layer is formed on the display surface of the display device. 4 can be easily manufactured in a display device in which the reflection is small and the transmittance of each emission wavelength is selectively adjusted. Further, the selective absorption characteristic of the colored pressure-sensitive adhesive layer 4, that is, the characteristic of absorbing (attenuating) light in a wavelength region (intermediate region between emission wavelength peaks) in which the emission spectra of the red, green, and blue phosphors overlap each other, The color reproduction area can be enlarged and the color purity can be improved.

The object to which the optical filter 1 of the present invention is applied includes not only a panel of a display device such as a cathode ray tube, a liquid crystal display device or a plasma display, but also a panel of various display devices. Further, a transmission type projector, a front plate of a cathode ray tube, and the like are also included.

FIG. 3 shows a color cathode ray tube having an optical filter 1 attached to a panel surface. In this structure, an example is shown in which the light absorbing film 3a also serves as a conductive film, and is configured to be able to prevent charging and cancel a leakage electromagnetic field.

The color cathode ray tube 10 has a fluorescent screen in which phosphor layers of red, green and blue light emission are arranged on the inner surface of the panel 12 of the tube body 11, and a color selection mechanism is arranged in close proximity to the fluorescent screen. And an electron gun is arranged in the neck portion 13.

The optical filter 1 is adhered to the surface of the panel 12 by the colored adhesive layer 4. Optical filter 1
The conductive film (light absorbing film) is connected to a conductive tape 14 by a method not shown, and the conductive tape 14 is connected to a tension band 15 wound around the outside of the panel 12. Therefore, the conductive film of the optical filter 1 is grounded through the conductive tape 14 and the tension band 15.

According to such a color cathode ray tube 10,
For example, the unbalance of the emission luminance of each color (red, green, blue) phosphor can be corrected by the optical filter 1 having a desired light transmittance difference with respect to the visible light wavelength. As a result, the cathode current ratio of each color at the time of white display is set as follows: red: green: blue = 1:
It can be 1: 1. Further, by lowering the overall transmittance, the contrast can be improved.

When the optical filter 1 is used as an ND filter by adjusting the selective transmission characteristics of the colored pressure-sensitive adhesive layer 4, dispersion of the transmittance of the antireflection film due to the light wavelength is corrected to make the transmittance visible. It is constant for any wavelength in the light region, and the optical filter 1 adjusts the light transmittance, thereby improving the contrast.

The optical filter 1 prevents external light and illumination light from being reflected on the display surface, so that a high-quality screen display can be realized. Further, the antistatic and / or the leakage electric field can be canceled, and the adverse effect on the human body can be prevented.

The transmissivity of a wide range can be adjusted only by retrofitting the optical filter 1 without requiring the panel 12 in which the light transmittance is adjusted, and the cost can be reduced. Irrespective of the mechanical strength of the tube 11, uniform transmittance can be obtained over the entire display surface.

FIG. 4 shows an embodiment in which the optical filter 1 is provided on the front plate of a transmission type projector or a cathode ray tube.
The front plate 20 is formed by attaching a transparent substrate 2 on which an anti-reflection film 3 is formed via a colored adhesive layer 4 to a surface of a transparent panel 21 made of an acrylic plate or the like.

The transmittance of such a front plate 20 can be adjusted by the optical filter 1 attached thereto.
As described above, for example, the luminance of each color light after passing through the front plate 20 can be made uniform. Further, for example, the transmittance is constant for any wavelength in the visible light region, and ND
A display function can be improved by having a filter function. Furthermore, the same effects as in the case of sticking to the surface of the panel 12 of the display device can be obtained, for example, high-quality screen display can be realized by preventing reflection of external light and illumination light.

In the above embodiment, the optical filter is obtained by combining the transparent base material 2 having the antireflection film 3 and the colored adhesive layer 4, but the present invention is not limited to this. An optical filter may be obtained by a combination of the transparent base material 2 without the protective film 3 and the colored adhesive layer 4.

Hereinafter, for the sake of clarifying the features of the present invention,
This will be described with reference to two examples. However, the present invention is not limited to these examples.

Example 1 (1) Preparation of Antireflection Film A transparent polyethylene terephthalate (PET) film having a thickness of 100 μm was used as a substrate. One surface of the PET film is previously subjected to a hard coat treatment for ensuring surface hardness. Further, a 130 nm-thick ITO (indium tin oxide) film serving as a light absorption film is pre-sputtered thereon by a sputtering method as an anti-reflection film, and a dielectric film of SiO ₂ film is formed thereon by 80 n.
m to form a two-layer antireflection film. According to a computer simulation, the antireflection film had a surface reflection of 1.56% luminous reflectance.
Table 1 shows the transmittances of the phosphors at three emission wavelength peaks (450 nm, 532 nm, and 626 nm) of the phosphor in a cathode ray tube (CRT). The transmission characteristics of the filter having only this antireflection film are shown by broken lines in FIG.

[0060]

[Table 1]

Table 2 shows the optical refractive index of the film material.
It is as follows.

[0062]

[Table 2]

As described above, by forming the antireflection film including the light absorbing film, the transmittance of red light is +1.
0%, and the blue transmittance was -7.1%.

(2) Formation of Colored Pressure-Sensitive Adhesive Layer A slurry-like coating material obtained by dissolving a pigment-added acrylic pressure-sensitive adhesive in a solvent is applied to the surface of the base material opposite to the antireflection film. , With a thickness of 50 μm. Then, it dried at 60 degreeC and formed the adhesion layer which has predetermined adhesive force. This pigment is obtained by mixing a plurality of organic pigments and has an absorption peak at a wavelength of 576 nm. As a result, the transmission characteristics of the filter (antireflection film + colored pressure-sensitive adhesive layer) were as shown by the solid line in FIG.

(3) Evaluation on a cathode ray tube When this filter was attached to a cathode ray tube and the display characteristics were examined, the transmittance of the filter was about 50% at the emission wavelength peaks of the three colors, and the filter was green. And the light between the red emission wavelength peaks was absorbed, so that among the three color emission characteristics of the cathode ray tube, the U ′ value of the red emission coordinate in the CIE1976 UCS chromaticity diagram was from 0.33 to 0.35.
It was expanded to. As a result, the filter simultaneously improved the contrast of the cathode ray tube and the color reproduction area and the color purity.

Example 2 (1) Preparation of Antireflection Film A transparent PET film having a thickness of 188 μm was used as a substrate. One surface of the PET film is previously subjected to a hard coat treatment for ensuring surface hardness. Further, a two-layer antireflection film is formed by sequentially laminating a TiN film serving as a light absorption film with a thickness of 7 nm and a SiO ₂ film serving as a transparent dielectric film with a thickness of 83 nm as a reflection prevention film by a sputtering method. did. According to a computer simulation, the antireflection film had a surface reflection of 0.27% luminous reflectance. Table 3 shows the transmittance at the peak emission wavelength of the three colors of the phosphor in the cathode ray tube (CRT). The transmission characteristics of the filter having only this anti-reflection film are shown by broken lines in FIG.

[0067]

[Table 3]

At this time, the optical refractive index of the film material is “<
The numerical values in Table 4 were used as the complex refractive index of the film material> = n-ik ". In the case of a transparent dielectric, k = 0.

[0069]

[Table 4]

As described above, by forming the anti-reflection film including the light absorbing film, the transmittance of red light is higher than that of green light by -3.
4%, and the blue transmittance was -1.6%.

(2) Formation of Colored Pressure-Sensitive Adhesive Layer A slurry-like coating material obtained by dissolving a pigment-containing acrylic pressure-sensitive adhesive in a solvent is applied to the surface of the substrate opposite to the antireflection film. , With a thickness of 50 μm. Then, it dried at 60 degreeC and formed the adhesion layer which has predetermined adhesive force. This pigment is, for example, Fe ₂ O ₃ (for red), TiO ₂ .ZnO.CoO, which is generally used as a “color filter” material to be added to a phosphor.
・ NiO (for green), CoO.Al ₂ O ₃ (for blue)
Obtained by mixing the types. FIG. 7 shows the transmission characteristics of this pigment. In the figure, curve I is the transmission characteristic of Fe ₂ O ₃ (for red), and curve II is TiO ₂ .ZnO.CoO.NiO.
(For green color), curve III is CoO.Al ₂ O
₃ shows transmission characteristics (for blue).

The curves a, b and c show ZnS: Ag which is a blue phosphor and ZnS: Cu: A which is a green phosphor.
1 shows respective emission spectra of Y ₂ O ₂ S: Eu which is a red phosphor. As is apparent from FIG. 7, the balance of the transmittance of each emission wavelength can be adjusted by the mixing ratio of the above three types of pigments, and the transmittance of red is + 13.4% compared to green by the colored adhesive layer. , Blue transmittance is +
By increasing the transmittance by 1.6%, a filter having a transmittance of 50% for blue and green and a transmittance of 60% for red was obtained. The transmission characteristics of the filter (antireflection film + colored pressure-sensitive adhesive layer) are shown by solid lines in FIG.

(3) Adhesion to cathode ray tube and evaluation When this filter was attached to a cathode ray tube and the display characteristics were examined, the transmittance of the filter was about 50% at the emission wavelength peak of three colors, and Since the light between the blue and green emission wavelength peaks and the light between the green and red emission wavelength peaks were respectively absorbed, 3
Among the emission characteristics of the colors, the U ′ value (V ′ value for blue) of the coordinates of each color emission in the CIE1976 UCS chromaticity diagram was improved by about 10%. As a result, the filter simultaneously improved the contrast of the cathode ray tube and the color reproduction area and the color purity.

Further, before the filter was attached, the cathode current ratio when displaying the white color of the cathode ray tube was measured, and it was blue: green: red = 1: 1: 1.2. After applying the filter, the transmittance of red (60%) is changed to other colors (50%).
%), The red cathode current during white display may be 20% lower, and the current ratio is blue: green: red =
It could be 1: 1: 1. As described above, in the cathode ray tube, it is more preferable to use not the “ND filter” having the same transmittance for all three colors but the characteristic of transmitting more red wavelengths.

As described above, in combination with an antireflection film including a light absorption film, by mixing two or more types of selectively permeable materials as pigments in the colored adhesive layer, an antireflection film (light absorption film) A filter having excellent transmission characteristics can be obtained without impairing the excellent anti-reflection characteristics. The same transmission characteristics can be obtained by mixing three types of organic pigments having the characteristics shown in FIG. 8 used in the color filter as the pigment. In this case, the transmission characteristics of the filter (the antireflection film + the colored adhesive layer) can be as shown by the solid line in FIG. 9 in combination with the antireflection film of the second embodiment.

[0076]

According to the present invention, a transparent pressure-sensitive adhesive layer is provided on one side of a transparent base material, and the colored pressure-sensitive adhesive layer is capable of transmitting light of a specific emission range among a plurality of emission wavelengths to another. By forming a layer having a property of transmitting light from the light-emitting region (selective transmission property), in combination with an anti-reflection film provided on the other surface side of the transparent substrate, excellent anti-reflection properties of the anti-reflection frame It is possible to suppress deterioration of display image quality and adjust the transmittance in a wide range while taking advantage of. As a result, the following effects can be obtained when applied to a display device. (1) The transmittance can be adjusted by the colored pressure-sensitive adhesive layer in accordance with the light emission characteristics of the display device or the transmission characteristics of the antireflection film, and a filter having excellent transmission characteristics can be obtained. (2) A wide range of transmittance can be adjusted without changing the material of the display panel. (3) Regardless of the mechanical strength of the display device, uniform transmittance can be obtained over the entire display surface. (4) In combination with an antireflection film, an excellent antireflection function can be added with a minimum number of layers.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an optical filter according to the present invention.

FIG. 2 is a diagram illustrating transmission characteristics of a colored pressure-sensitive adhesive layer.

FIG. 3 is a configuration diagram of a cathode ray tube having an optical filter.

FIG. 4 is a sectional view of a front plate for a display device having an optical filter.

FIG. 5 is a transmission characteristic diagram according to the first embodiment of the present invention.

FIG. 6 is a transmission characteristic diagram according to the second embodiment of the present invention.

FIG. 7 is a graph showing the transmission characteristics of a pigment used in the description of the present invention.

FIG. 8 is a graph showing transmission characteristics of an organic pigment used in the description of the present invention.

FIG. 9 is a transmission characteristic diagram when three colors of organic pigments used in the description of the present invention are mixed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical filter, 2 ... Transparent base material, 3 ... Antireflection film,
3a: light absorbing film, 3b: transparent dielectric film, 4: colored adhesive layer, 10: cathode ray tube, 20: front panel for display device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kunio Ikui, 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Shiro 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F term (reference) 2H048 CA04 CA05 CA14 CA19 CA24 CA25 CA29 2K009 AA05 AA15 BB24 CC03 DD04 5C058 AA01 BA35 DA01 DA07 5G435 AA00 AA01 BB02 BB06 BB12 CC12 FF01 FF14 GG11 GG32 H03 H05 H05 H03 H05

Claims (11)

[Claims] 1. A colored pressure-sensitive adhesive layer is provided on one surface side of a transparent substrate, and the colored pressure-sensitive adhesive layer includes a plurality of emission wavelengths
An optical filter having a characteristic of transmitting light in a specific light-emitting region more than light in another light-emitting region. 2. The optical filter according to claim 1, wherein the colorant in the colored pressure-sensitive adhesive layer is a mixture of two or more dyes or pigments. 3. The colored pressure-sensitive adhesive layer has a transmittance characteristic lower than the transmittance of two adjacent emission wavelength peaks in a region between a plurality of emission wavelength peaks. The optical filter as described. 4. The optical filter according to claim 1, wherein at least one or more antireflection films are provided on the other surface of the transparent substrate. 5. The optical filter according to claim 4, wherein the antireflection film has a film configuration of two or more layers including a light absorbing film. 6. The optical filter according to claim 5, wherein the light absorbing film is made of a metal, a metal oxide, a metal nitride, or a metal oxynitride. 7. A colored pressure-sensitive adhesive layer is provided on one surface side of a transparent substrate, and the colored pressure-sensitive adhesive layer has a lower transmittance in a region between a plurality of emission wavelength peaks than a transmittance of two adjacent emission wavelength peaks. An optical filter having transmittance characteristics. 8. A colored pressure-sensitive adhesive layer is provided on one surface side of a transparent substrate, and the colored pressure-sensitive adhesive layer has a plurality of emission wavelengths.
A display device comprising an optical filter having a characteristic of transmitting light in a specific light-emitting region more than light in another light-emitting region. 9. A colored pressure-sensitive adhesive layer is provided on one surface side of a transparent substrate, and the colored pressure-sensitive adhesive layer has a lower transmittance in a region between a plurality of emission wavelength peaks than a transmittance of two adjacent emission wavelength peaks. A display device comprising an optical filter having transmittance characteristics. 10. A colored pressure-sensitive adhesive layer is provided on one surface side of a transparent substrate, and the colored pressure-sensitive adhesive layer transmits light in a specific luminous region of the plurality of emission wavelengths more than light in other luminous regions. A front plate for a display device, comprising: an optical filter having a characteristic of causing the display device to have a characteristic. 11. A colored pressure-sensitive adhesive layer is provided on one surface side of a transparent substrate, and the colored pressure-sensitive adhesive layer has a lower transmittance in a region between a plurality of emission wavelength peaks than two adjacent emission wavelength peaks. A front panel for a display device, comprising an optical filter having transmittance characteristics.