JP2009198588A - Optical filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical filter for improving contrast of images by reducing reflection caused by external light on a display face such as a PDP and preventing the images from blurring even when exposed to external light. <P>SOLUTION: The film-like optical filter 11 includes: an electromagnetic wave shielding laminate layer 12 having an electromagnetic wave shielding layer 22 comprising metal meshes formed on the surface of a transparent base material 21 having flexibility, and a transparent adhesion layer 23 to be bonded on a display face 17a of a PDP module 17 on a rear face; an external light shielding layer 13 integrated through a transparent adhesion layer 33 with the electromagnetic wave shielding laminate layer 12; and a release film 16 bonded on the transparent adhesion layer 23 of the electromagnetic wave shielding laminate layer 12. The optical filter is directly bonded on the display face 17a of the PDP module 17 by peeling the release film 16. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical filter. More specifically, the present invention is suitably used for a display surface of a display device such as a plasma display panel (PDP), and reduces the amount of reflected light caused by external light even in an environment where external light is applied. The present invention relates to an optical filter capable of improving the contrast of an image by reducing the contrast.

In recent years, a plasma display panel (PDP) has been developed and put into practical use as a large screen and thin receiver.
In this PDP, a front glass substrate having a display electrode, a bus electrode, a dielectric layer, and a protective layer, and a rear glass substrate having a data electrode, a dielectric layer, a stripe-shaped partition wall, and a phosphor layer are provided. A display cell is formed by bonding the electrodes and the data electrodes so as to be orthogonal to each other, and a discharge gas such as a He—Xe mixed gas is enclosed in the display cell.
In this PDP, by applying a voltage between the data electrode and the display electrode, the xenon is discharged in the display cell, and the xenon resonance line (147 nm) when the xenon ion in the plasma state returns to the ground state. ) Is generated, and the ultraviolet light excites the phosphor to emit light of each color of red (R), green (G), and blue (B), thereby enabling color display.
This PDP has a small installation space as a thin display device, and is considered useful as a display device such as a wall-mounted television.

In this PDP, near-infrared rays and electromagnetic waves are also generated in addition to the visible light in the process of emitting visible light. Therefore, in order to cut these near infrared rays and electromagnetic waves, it is common to provide an optical filter provided with an antireflection function, a near infrared shielding function, and an electromagnetic wave shielding function on the surface of the front glass substrate serving as a display unit. is there.
As the optical filter, an optical filter of a type in which a film laminate in which several layers of films are laminated is attached to a glass substrate is generally used.
However, in this optical filter, since the distance from the display surface of the PDP is separated, the light irradiation range in the PDP pixels is expanded. When this light is incident on the optical filter at an angle, the light is reflected by the internal electromagnetic shielding layer or the like and output. Therefore, when used in an environment exposed to external light, there is a problem that the direct output light from the display surface of the PDP and the reflected light reflected in a wide range from the outside overlap and the image is blurred.
Therefore, for the purpose of preventing blurring of the image, a film type optical filter that is directly attached to the display surface of the PDP has been proposed (see, for example, Patent Document 1).

FIG. 2 is a cross-sectional view showing an example of a conventional film type optical filter for PDP. In FIG. 2, reference numeral 1 denotes an optical filter attached to the display surface of the PDP module, and an antireflection function and a near infrared shielding function. By adhering the composite film layer 2 having the above and the laminated body layer 3 having the electromagnetic wave shielding function, a single film-like laminate is obtained as a whole.
The composite film layer 2 includes a film-like transparent substrate 4, an antireflection layer 5 formed on the upper surface thereof, a near infrared shielding layer 6 formed on the lower surface on the opposite side, and a lower surface of the near infrared shielding layer 6. The adhesive layer 7 formed in the above is joined and integrated.
The laminated body layer 3 is formed by bonding and integrating an electromagnetic wave shielding material layer 8 made of a metal mesh and an adhesive layer 9 formed on the entire lower surface of the electromagnetic wave shielding material layer 8. A release film (release material) 10 is detachably attached to the side.
The composite film layer 2 and the laminate layer 3 are bonded and integrated by the adhesive layer 7 to constitute the optical filter 1. At this time, a grounding electrode (not shown) is provided on the electromagnetic wave shielding material layer 8. It is configured to be attached.

In this optical filter 1, after peeling off the release film 10, the adhesive layer 9 is directly attached to the display surface of the PDP module, so that the display surface has an antireflection function, a near infrared shielding function, an electromagnetic wave shielding function, etc. Since the structure is provided with a plurality of functions, there is no space between the optical filter 1 and the PDP module as in the prior art. Therefore, reflection on the display surface of the PDP module is prevented, and light from the PDP module is prevented. It prevents diffusion and prevents image blurring.
JP 2007-57889 A

  However, in the above-described conventional film type optical filter, the electromagnetic wave shielding material layer is formed by forming a fine metal pattern on the surface of the resin film, for example, after attaching copper foil to the surface of the resin film, Since it is composed of finely etched lines, when used in an environment exposed to external light, the external light is reflected on the surface of the metal's fine pattern, preventing sufficient reflection prevention on the display surface. There was no problem. This reflection phenomenon on the surface promotes blurring of the image and deteriorates the contrast on the display surface.

  In addition, since many PDP modules have a white phosphor inside, when external light hits the display surface, the external light is not only reflected on the display surface but also strongly reflected from the phosphor portion. Will be. When the above-described conventional film-type optical filter is directly attached to the display surface of the PDP module, reflection of external light from the display surface can be prevented, but reflection from the phosphor portion cannot be prevented. Therefore, the blurring of the image is also promoted by the external light reflected from the phosphor portion, and the contrast on the display surface is deteriorated.

  The present invention has been made to solve the above-described problem, and reduces reflection caused by external light on a display surface of a display device such as a plasma display panel (PDP) even in an environment where external light is applied. Therefore, an object of the present invention is to provide an optical filter that can prevent blurring of an image and consequently improve the contrast of the image.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have determined that the main body portion of the optical filter is applied to the electromagnetic wave shielding layer of the flexible electromagnetic wave shielding laminate layer and the flexible external light shielding layer. If the transparent adhesive layer for adhering to the display surface of the display device is formed on the surface of the electromagnetic wave shielding laminate layer opposite to the outside light shielding layer, the optical filter is displayed. It can be directly attached to the display surface of the device, the amount of reflected light caused by external light on the display surface of this display device can be reduced, and blurring of the image can be prevented, and as a result, The inventors have found that the deterioration of the contrast of the image can be prevented, and have completed the present invention.

  That is, the optical filter of the present invention is an optical filter that is directly attached to the display surface of a display device, and an electromagnetic wave shielding layer is formed on one main surface of a flexible transparent substrate, and the other An electromagnetic wave shielding laminate layer having a transparent adhesive layer for adhering to the display surface on the main surface, and an external light shielding layer having flexibility and bonded to the surface of the electromagnetic wave shielding layer. It is characterized by.

In this optical filter, the transparent adhesive layer is directly attached to the display surface of the display device, so that the optical filter is closely attached and fixed with no space between the display surface of the display device.
In addition, by providing an external light shielding layer on the main surface opposite to the side to be adhered to the display surface of the electromagnetic wave shielding laminate layer, even when used in an environment exposed to external light, The external light shielding layer shields light and prevents the light from entering the electromagnetic wave shielding layer or the PDP module. Thereby, reflection from the surface of the electromagnetic wave shielding layer and the phosphor part of the PDP module due to the incidence of external light is prevented.
Therefore, it is possible to prevent reflection and blurring of the image due to the external light, and it is possible to improve the contrast of the display surface.

The optical filter of the present invention is characterized in that either one or both of an antireflection layer and a near-infrared shielding layer are laminated on the surface of the external light shielding layer.
This optical filter has an antireflection function and a near infrared shielding function in addition to an external light shielding function by laminating one or both of an antireflection layer and a near infrared shielding layer on the surface of the external light shielding layer. It becomes possible to do.

In the optical filter of the present invention, the electromagnetic wave shielding layer is a net-like metal layer.
The visible light transmittance is 20% or more.
A release material is detachably attached to the transparent adhesive layer.
The display device is a plasma display panel.

According to the optical filter of the present invention, an electromagnetic wave shielding layer is formed on one main surface of a flexible transparent substrate, and a transparent adhesive layer for adhering to the display surface is formed on the other main surface. Since it has an electromagnetic wave shielding laminate layer and an external light shielding layer that is bonded to the surface of the electromagnetic wave shielding layer and has flexibility, even when used in an environment exposed to external light, it is caused by this external light. Reflection and blurring of the image can be prevented, and thus the contrast of the display surface can be improved.
As described above, the visibility and reliability in the display unit can be further improved.

The best mode of the optical filter of the present invention will be described.
This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

FIG. 1 is a cross-sectional view showing an optical filter according to an embodiment of the present invention. In this figure, in order to make the structure easy to understand, the thickness of each layer is different from the actual one.
In the figure, 11 is an optical filter, an electromagnetic wave shielding laminate layer 12, an external light shielding layer 13, a near-infrared shielding layer 14, and an antireflection layer 15 are joined and integrated, and further an electromagnetic shielding laminate layer. 12, a flexible release film (peeling material) 16 is detachably attached so that the entire film is flexible.

The electromagnetic wave shielding laminate layer 12 has an electromagnetic wave shielding layer 22 formed on the surface (one main surface) of the transparent substrate 21 having flexibility, and is pasted on the display surface 17a of the PDP module 17 on the back surface (the other main surface). A transparent adhesive layer 23 for wearing is formed.
The transparent substrate 21 is not particularly limited as long as it has flexibility and transparency with respect to visible light. For example, a transparent resin that is an organic polymer material is preferable.

  As this transparent resin, resins such as polyester (PE), triacetylcellulose, polycarbonate (PC), polyethersulfone (PES), polyacrylate (PAC), norbornene, and amorphous polyolefin are preferably used. Of these, polyester is preferable, and polyethylene terephthalate (PET) is particularly preferable because of excellent durability, solvent resistance, productivity, and the like.

The shape of the transparent substrate 21 is not particularly limited as long as it has flexibility, and can be appropriately selected depending on the application, such as a film shape or a sheet shape. Also, the thickness is not particularly limited, but in consideration of handling and the like, a film shape of about 20 μm to 1 mm is preferable.
Moreover, in order to adjust a color tone and the transmittance | permeability, you may use what mixed the coloring agent and dye into transparent resin.

The electromagnetic wave shielding layer 22 is not particularly limited as long as it has shielding properties against electromagnetic waves and transparency to visible light. However, a net-like metal layer such as a metal mesh is preferable from the viewpoint of handling.
As the metal mesh, for example, (1) a paste containing a catalyst such as palladium is printed on a predetermined mesh pattern, and then a metal such as copper is plated on the mesh pattern, (2) vapor deposition method, sputtering method, etc. A conductive material such as silver or aluminum is formed in a mesh pattern, (3) A metal plating layer such as copper is etched to form a mesh pattern, and (4) A metal foil such as copper is etched. Can be used, and (5) a mesh in which a metal is plated on the surface of a fiber and affixed on the transparent substrate 21 can be used.

  The thickness of the electromagnetic wave shielding layer 22 is preferably 1 μm or more and 10 μm or less. The reason is that when a metal mesh is used as the electromagnetic wave shielding layer 22, if the thickness of the metal mesh is larger than 10 μm, the viewing angle is narrowed and the visibility is lowered, and further, the surface is blackened. However, when viewed from an oblique direction, the depth direction of the metal mesh is difficult to be blackened, and the color of the metal constituting the metal mesh appears strongly, causing a problem in the color tone of the display surface.

A transparent conductive film can be used instead of the metal mesh.
Examples of the transparent conductive film include tin-added indium oxide (ITO), antimony-added tin oxide (ATO), zinc-added indium oxide (IZO), aluminum-added zinc oxide (AZO), and gallium-added zinc oxide (GZO). A transparent conductive film is preferred.

When this transparent conductive film is used for the electromagnetic wave shielding layer 22, reflection like a metal mesh is greatly reduced. That is, with respect to the electromagnetic wave shielding layer, it is not necessary to shield incident external light, and only the PDP module needs to be shielded.
Therefore, there is no need to provide the external light shielding layer 13 on the opposite side (viewing side) of the electromagnetic shielding laminate layer 12 to the side attached to the display surface 17 a of the PDP module 17. You may make it provide the external light shielding layer 13 in the side stuck by the display surface 17a of the PDP module 17. FIG.

As the transparent adhesive layer 23, a resin adhesive having transparency to visible light is preferably used. Examples of the resin adhesive include a silicon resin adhesive and an acrylic resin adhesive.
The adhesive strength of the transparent adhesive layer 23 is preferably 1 to 10 N / 25 mm, more preferably 4 to 8 N / 25 mm at the initial stage of formation of the adhesive layer.
The adhesive strength of the transparent adhesive layer 23 has a characteristic that it gradually increases and reaches equilibrium every time after the initial formation, and then gradually decreases. Therefore, the adhesive strength at the time when the equilibrium is reached is more preferably 10 to 15 N / 25 mm.

  If this adhesive strength is in the range of 1 to 10 N / 25 mm, when this optical filter 11 is attached to the display surface 17 a of the PDP module 17, the adhesive state can be maintained practically sufficiently, When it becomes necessary to peel off the optical filter 11 from the display surface 17a, it can be peeled off without any practical difficulty. In this case, the peeled optical filter 11 can be reused, and the expensive display device body can be used continuously.

  The external light shielding layer 13 is for preventing light incident from the outside from entering the inside of the external light shielding layer 13, that is, the electromagnetic wave shielding layer 22 and the PDP module 17, for example, at a predetermined interval. Consists of a wedge section 31 having a wedge-shaped cross section that is arranged in parallel to each other and has a light absorption effect, and a transparent section 32 having a low refractive index that fills the wedge section 31, and makes light incident from outside the wedge section 31 and the transparent section. It can be shielded by refracting and absorbing the wedge portion 31 at the boundary surface with 32. Thereby, the contrast in the image displayed through the optical filter from the display surface 17a of the PDP module 17 can be increased, and the ghost can be suppressed.

In addition, the structure of this external light shielding layer 13 should just be a structure which can prevent the incident light from the outside entering into the inside of the external light shielding layer 13, and is not limited to said structure.
The external light shielding layer 13 covers the electromagnetic wave shielding layer 22 with the transparent adhesive layer 33 made of the same material as the transparent adhesive layer 23 described above, and is attached to the electromagnetic wave shielding laminate layer 12 so as to be joined and integrated. .

In the near-infrared shielding layer 14, a near-infrared shielding film 42 is formed on the surface (one main surface) of the transparent base 41 having flexibility made of the same material as the transparent base 21 described above.
The near-infrared shielding layer 14 is bonded to the external light shielding layer 13 by a transparent adhesive layer 43 made of the same material as the transparent adhesive layer 23 described above, and is integrally joined.

  The near-infrared shielding film 42 only needs to have a shielding property against near-infrared rays in a wavelength band of 800 to 1100 nm. For example, a near-infrared absorbing dye is contained in a resin matrix made of acrylic resin, methacrylic resin, or the like. It is preferable that they are dispersed. As the resin matrix, an adhesive layer can be selected. For example, if an antireflection film is formed on the surface of the transparent substrate and an adhesive layer having a near infrared shielding function is formed on the back surface, the number of layers can be greatly reduced.

The near-infrared absorbing dye is not particularly limited as long as it is a dye having a shielding property against near-infrared rays in the wavelength band of 800 to 1100 nm. Compounds, cyanine compounds, azo compounds, polymethine compounds, quinone compounds, diphenylmethane compounds, triphenylmethane compounds, mercaptonaphthol compounds, etc. can be used. Or you may use 2 or more types in combination as appropriate.
In particular, diimonium compounds have excellent near-infrared shielding properties because they have a strong absorbency with a molar extinction coefficient of about 100,000 in the near-infrared region with a wavelength of 850 to 1100 nm.

  In order for the near-infrared shielding film 42 to exhibit practically sufficient near-infrared shielding properties, it is preferable that the near-infrared transmittance in the wavelength band of 900 to 1000 nm is 20% or less.

In the antireflection layer 15, an antireflection film 45 is formed on the surface (one main surface) of a transparent base material 44 made of the same material as that of the transparent base material 21 described above.
The antireflection layer 15 is attached to the near infrared shielding layer 14 by a transparent adhesive layer 46 made of the same material as the transparent adhesive layer 23 described above, and is integrally joined.
The antireflection film 45 only needs to prevent reflection of light incident from the outside, and may have a single layer structure or a laminated structure.

As the antireflection film having a laminated structure, for example, a combination of a plurality of layers having different refractive indexes is preferable. As a combination of refractive indexes, in addition to two types of combinations of a low refractive index layer and a high refractive index layer, a combination of three types of a low refractive index layer, a middle refractive index layer, and a high refractive index layer may be used.
In addition, a hard coat layer for preventing scratches, a conductive layer for preventing adhesion of dust due to static electricity, and the like can be used in combination as necessary.

  Note that, depending on the type of the antireflection film, there is an increase in the amount of transmitted light radiated from the outside due to the expression of the antireflection function. In this case, compared with the case where there is no antireflection film, more of the light irradiated from the outside is incident on the electromagnetic wave shielding layer 22 and the PDP module 17, which promotes a decrease in contrast in the image and the occurrence of ghost. Become. In such a case, it is more important to provide the external light shielding layer 13.

In this optical filter 11, the visible light transmittance is preferably 20% or more, more preferably 30% or more.
The reason is that when the visible light transmittance is lower than 20%, the light emitted from the PDP module 17 is not sufficiently transmitted, and the luminance as a display device is insufficient.
On the other hand, when the transmittance is increased, there are many phosphors in the PDP module 17 that are close to white, so that particularly the dark black display portion becomes whitish and the contrast of the screen decreases. Therefore, the PDP optical filter uses a method of obtaining contrast by setting the transmittance low and increasing the emission intensity of the phosphor in the PDP module 17 for insufficient luminance.

In particular, the visible light transmittance at a wavelength of 590 nm is preferably 10% or more lower than the visible light transmittance at wavelengths of 450 nm, 525 nm, and 620 nm. Thereby, when this optical filter 11 is used, the contrast of the display surface 17a of the PDP module 17 is improved, and the color tone correction function is enhanced.
Thus, in order to make visible light transmittance at a wavelength of 590 nm 10% or more lower than visible light transmittance at each wavelength of 450 nm, 525 nm, and 620 nm, the quinacridone pigment is included in the near-infrared shielding film 42. It is preferable to contain a selective absorptive colorant such as an azomethine compound, a cyanine compound, and a porphyrin compound.

The optical filter 11 can be integrated with the PDP module 17 by peeling the release film 16 and sticking it to the display surface 17 a of the PDP module 17.
In this optical filter 11, the release film 16 is peeled off from the electromagnetic wave shielding laminate layer 12, and the exposed transparent adhesive layer 23 is attached to the display surface 17 a of the PDP module 17, whereby the optical filter 11 is attached to the PDP. It can be attached to the display surface 17a of the module 17 and joined together.

  Further, since this optical filter 11 is bonded and integrated with the display surface 17a of the PDP module 17 with a relatively weak adhesive force of the transparent adhesive layer 23, the optical filter 11 is attached to the display surface of the PDP module 17 with a relatively small force. It is possible to peel from 17a. Therefore, when it is desired to replace the optical filter 11 with another type of optical filter, or when the optical filter 11 has deteriorated due to long-term use, the optical filter 11 is peeled off from the display surface 17a of the PDP module 17. Thereafter, another optical filter may be attached to the display surface 16a.

The optical filter 11 is directly attached to the display surface 17a of the PDP module 17, so that the optical filter 11 is in close contact with the display surface 17a of the PDP module 17 in a state where there is no space.
Further, by providing the external light shielding layer 13 on the surface of the electromagnetic wave shielding laminate layer 12, the external light shielding layer 13 effectively shields the incident external light even when used in an environment where external light is applied. To do. Thereby, external light is effectively prevented from entering the electromagnetic wave shielding laminate layer 12, and reflection on the surface of the electromagnetic wave shielding layer 22 due to the incidence of external light is prevented.

Further, since the incident external light can be effectively blocked by the external light shielding layer 13, the external light can be effectively prevented from entering the PDP module 17, and the PDP module caused by the incident external light can be prevented. Reflection from 17 phosphor portions is prevented.
As described above, the optical filter 11 is directly attached to the display surface 17a of the PDP module 17, so that reflection and blurring of the image due to the external light can be prevented, and the optical filter is passed from the display surface 17a. It is possible to improve the contrast of the displayed image.

  As described above, according to the optical filter 11 of the present embodiment, the electromagnetic wave shielding laminate layer 12, the external light shielding layer 13, the near infrared shielding layer 14, and the antireflection layer 15 are joined and integrated. Even when used in an environment exposed to external light, the external light can be prevented from entering the PDP module 17 by shielding the external light with the external light shielding layer 13, and reflection caused by the external light can be prevented. In addition, blurring of the image can be prevented.

  Further, since the electromagnetic wave shielding laminate layer 12 is provided on the surface of the external light shielding layer 13, that is, the surface facing the display surface 17 a of the PDP module 17, the external light is shielded by the external light shielding layer 13 and the electromagnetic wave shielding laminated layer. There is no possibility of entering the body layer 12, reflection on the surface of the electromagnetic wave shielding laminate layer 12 can be prevented, and therefore blurring of the image can be prevented, and an image displayed through the optical filter from the display surface 17a. The contrast in can be improved.

  Further, there is no possibility that the external light is blocked by the external light shielding layer 13 and enters the PDP module 17, and reflection on the phosphor portion of the PDP module 17 can be prevented. Therefore, blurring of the image due to the external light can be prevented, and contrast in an image displayed from the display surface 17a through the optical filter can be improved.

Moreover, since the optical filter 11 can be directly attached to the display surface 17a of the PDP module 17 by peeling off the release film 16 attached to the electromagnetic wave shielding laminate layer 12, one pixel of the PDP module 17 The irradiation range of the hit output light is narrowed, and the reflected output light of the external light shielding layer 13 due to the output light is also reduced. Further, reflection on the back surface of the optical filter 11 and the display surface 17a of the PDP module 17 can be prevented.
Therefore, reflection on the display surface 17a of the PDP module 17 and blurring of the image can be prevented.
As described above, the visibility and reliability on the display surface 17a of the PDP module 17 can be further improved.

  In the optical filter of the present invention, an electromagnetic wave shielding layer is formed on one main surface of a flexible transparent substrate, and a transparent adhesive layer for adhering to the display surface is formed on the other main surface. Even when used in an environment exposed to external light, the electromagnetic wave shielding laminate layer and an external light shielding layer having one main surface bonded to the electromagnetic wave shielding layer and having flexibility are used. Since it is possible to prevent the reflection and the blurring of the image, it can be applied not only to the PDP but also to a display device such as an electroluminescence (EL) display. The effect is very big.

It is sectional drawing which shows the optical filter of one Embodiment of this invention. It is sectional drawing which shows an example of the conventional optical filter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Optical filter 12 Electromagnetic wave shielding laminated body layer 13 External light shielding layer 14 Near-infrared shielding layer 15 Antireflection layer 16 Peeling film 17 PDP module 17a Display surface 21 Transparent base material 22 Electromagnetic wave shielding layer 23 Transparent adhesive layer 31 Wedge part 32 Transparent part 33 Transparent adhesive layer 41 Transparent base material 42 Near-infrared shielding film 43 Transparent adhesive layer 44 Transparent base material 45 Antireflection film 46 Transparent adhesive layer

Claims (6)

An optical filter directly attached to the display surface of the display device,
An electromagnetic wave shielding layer formed with an electromagnetic wave shielding layer formed on one main surface of the transparent substrate having flexibility and a transparent adhesive layer for adhering to the display surface on the other main surface;
An external light shielding layer bonded to the surface of the electromagnetic shielding layer and having flexibility;
An optical filter comprising:   2. The optical filter according to claim 1, wherein one or both of an antireflection layer and a near-infrared shielding layer are laminated on the surface of the external light shielding layer.   3. The optical filter according to claim 1, wherein the electromagnetic wave shielding layer is a net-like metal layer.   4. The optical filter according to claim 1, wherein the visible light transmittance is 20% or more.   The optical filter according to claim 1, wherein a release material is detachably attached to the transparent adhesive layer.   The optical filter according to claim 1, wherein the display device is a plasma display panel.

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