JP2013004801A - Laminate and image display apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate which can obscure moire.SOLUTION: A laminate 20 comprises: an optical member 50 including plural linear light shield parts 60 aligned with an interval therebetween; and an electromagnetic wave shielding material 30 having a conductive mesh 40 defining a number of opening regions 42. The conductive mesh 40 has a pattern formed by a number of boundary line segments 48 each of which extends between two branch points 46 and defines the opening regions 42. In the pattern, the average number of the boundary line segments 48 extending out from one of the branch points 46 is 3.0 or more and less than 4.0. There is no direction in which the opening regions 42 are arranged with a constant pitch therebetween.

Description

  The present invention relates to a laminate including an optical member having a light-shielding portion and an electromagnetic wave shielding material having a conductive mesh, and in particular, it is possible to effectively suppress the occurrence of moire and the occurrence of shading unevenness. It relates to a laminate. The present invention also relates to an image display device having this laminate, and more particularly to an image display device capable of effectively suppressing the occurrence of moiré and shading unevenness.

  Conventionally, an image display apparatus having an image forming apparatus such as a plasma display panel (PDP) or a cathode ray tube (CRT) has been widely used. In these image display devices, a laminate composed of a plurality of sheet-like (film-like) members each provided with various functions on the image observer side (also referred to as the screen side or the front side) of the image forming device. Is arranged.

  Patent Documents 1 and 2 disclose an electromagnetic wave shielding material (electromagnetic wave shielding sheet) as an example of a member that can be included in such a laminate. Such an electromagnetic wave shielding material is a sheet-like member for transmitting image light out of radiation radiated from the screen of the image forming apparatus and shielding unnecessary electromagnetic waves in the frequency band of about kHz to GHz. In a widespread form, the electromagnetic shielding material includes a conductive mesh that defines a number of open areas. The conductive mesh is typically made of a conductor formed in a pattern having a regular repeating period forming a square lattice.

  In addition, examples of the member that can be included in the laminate include an optical member that has translucency and can absorb unnecessary light. As an example, Patent Document 3 discloses an optical member disposed on a screen of an image forming apparatus that forms an image. The optical member in Patent Document 3 has light absorbing portions and prism portions that are alternately arranged in a stripe shape. The prism portion can transmit image light forming an image, and the light absorbing portion can absorb external light including ambient light such as sunlight and illumination light as unnecessary light. According to such an optical member, it is possible to effectively increase the contrast of the image (the ratio of the white image luminance to the black image luminance) by absorbing unnecessary light. Further, by appropriately designing the dimensions and refractive indexes of the prism portion and the light absorbing portion, the emission direction of the image light can be enlarged or reduced.

WO2007 / 114076 JP-A-11-121974 JP 2008-170975 A

  However, when the optical member in which the light absorbing portions are repeatedly arranged and the electromagnetic shielding material having the conductive mesh are stacked in one laminated body, the periodicity of the light absorbing portion and the periodicity of the electric mesh A striped pattern resulting from interference, that is, moire (interference fringes) may be visually recognized. In addition, an image forming apparatus typified by a PDP, a CRT, or the like has a pixel array having a repeating cycle, and forms a desired image by controlling light for each pixel. For this reason, when an optical member and an electromagnetic wave shielding material are arranged on the image forming apparatus, it is more complicated due to interference between the periodicity of the pixel array, the periodicity of the light absorbing portion, and the periodicity of the conductive mesh. Moiré can be visually recognized. Such moire is displayed by the image display device and significantly deteriorates the image quality.

  In Patent Document 1 and Patent Document 2, it is proposed to improve the mesh pattern of the conductive mesh in order to prevent the occurrence of moire. In Patent Document 1, it is proposed to produce a conductive mesh by chemical treatment combining organic solvent treatment and acid treatment. This conductive mesh has a completely randomized pattern and is effective in eliminating moire. However, the pattern of the conductive mesh disclosed in Patent Document 1 inevitably includes roughness in the pattern itself, and uneven appearance of density due to the roughness occurs. When the conductive mesh disclosed in Patent Document 1 is arranged on the image forming apparatus, unevenness in brightness is visually recognized, and the image quality is remarkably deteriorated. Moreover, the pattern of the conductive mesh disclosed in Patent Document 1 comes to include a disconnected portion, and the portion does not function effectively for the purpose of shielding electromagnetic waves, but also has a problem of reducing transparency. Also come.

  On the other hand, although the pattern of the conductor mesh of the electromagnetic wave shielding material disclosed in Patent Document 2 does not include the disconnection portion, it is not completely randomized and partially remains periodic. When the electromagnetic wave shielding material disclosed in Patent Document 2 is used, it is possible to suppress the occurrence of shading unevenness while ensuring sufficient electromagnetic wave shielding properties, but the moire cannot be made sufficiently inconspicuous.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a laminate capable of making the uneven density and moire inconspicuous, and an image display device including the laminate.

The laminate according to the present invention comprises:
An optical member including a plurality of light shielding portions arranged at intervals, and
An electromagnetic shielding material having a conductive mesh that defines a large number of opening regions, and
The conductive mesh is formed from a number of boundary segments that extend between two branch points to define the open area;
The conductive mesh has a pattern in which an average number of boundary line segments extending from one branch point is 3.0 or more and less than 4.0 and there is no direction in which the opening regions are arranged at a constant pitch. Including the region.

  In the region of the laminate according to the present invention, the average of the number of boundary line segments connected at one branch point may be larger than 3.0.

  In the region of the laminate according to the present invention, the average of the number of boundary line segments connected at one branch point may be 3.0.

  In the laminate according to the present invention, the electromagnetic wave shielding material may further include a transparent substrate that supports the conductive mesh.

  In the laminate according to the present invention, the conductive mesh may include a plurality of the regions, and the plurality of regions may have the same pattern.

In the laminate according to the present invention,
The plurality of regions are arranged at a predetermined pitch in a certain direction,
The predetermined pitch may be 1/10 or more of the dimension of the image forming apparatus along the certain direction.

An image forming apparatus according to the present invention includes:
An image forming apparatus;
Any of the above-described laminates according to the present invention, comprising: a laminate provided on the image forming apparatus.

  According to the present invention, the conductive mesh of the electromagnetic wave shielding material has a pattern formed from a number of boundary lines extending between two branch points to define an opening region, and in this pattern, one branch The average number of boundary line segments extending from the point is 3.0 or more and less than 4.0, and there is no direction in which the open regions are arranged at a constant pitch (period) (the array has repeated regularity) There is no direction). As a result, moire and shading unevenness can be made extremely inconspicuous.

FIG. 1 is a diagram for explaining an embodiment of the present invention, and is a cross-sectional view showing a schematic configuration of an image display device and a laminated body. FIG. 1A is a diagram corresponding to FIG. 1, and is a diagram for explaining a modified example of the laminated body. FIG. 2 is a cross-sectional view showing an optical member that can be incorporated into the image display device and the laminate of FIG. 1 in a cross section along the normal direction. 3 is an enlarged view of a part of the optical functional layer including the light shielding portion of the optical member shown in FIG. 2 in the same cross section as FIG. FIG. 4 is a cross-sectional view showing an aspect of the optical functional layer (light-shielding portion) of the optical member different from the aspect shown in FIG. 3 in the same cross section as FIG. FIG. 5 is a cross-sectional view showing an aspect of the optical functional layer (light-shielding portion) of the optical member, which is different from the aspect shown in FIG. FIG. 6 is a cross-sectional view showing an aspect of the optical function layer (light-shielding portion) of the optical member that is different from the aspect shown in FIG. 3 in the same cross section as FIG. FIG. 7 is a cross-sectional view showing an aspect of the optical functional layer (light-shielding portion) of the optical member that is different from the aspect shown in FIG. 3 in the same cross section as FIG. FIG. 8 is a plan view showing an embodiment of an optical member that can be incorporated into the image display device and laminated body of FIG. 1, and is for explaining patterns in a plan view of a light shielding portion and a light transmitting portion of the optical member. FIG. FIG. 9 is a plan view showing an electromagnetic wave shielding material that can be incorporated into the image display device and the laminate of FIG. 1 and is a view for explaining a pattern of a conductive mesh of the electromagnetic wave shielding material. FIG. 10 is a partially enlarged view of FIG. 9 for explaining the pattern of the conductive mesh of the electromagnetic wave shielding material. 11 is a plan view showing a state in which the optical member shown in FIG. 8 and the electromagnetic wave shielding material shown in FIG. 9 are overlapped. FIG. 12 is a plan view for explaining a pixel arrangement of an image forming apparatus that can be incorporated in the image display apparatus of FIG. 13 is a plan view showing a state in which the optical member shown in FIG. 8 and the image forming apparatus shown in FIG. 12 are overlapped. 14 is a plan view showing a state in which the electromagnetic wave shielding material shown in FIG. 9 and the image forming apparatus shown in FIG. 12 are overlapped. 15 is a plan view showing a state in which the optical member shown in FIG. 8, the electromagnetic wave shielding material shown in FIG. 9, and the image forming apparatus shown in FIG. 12 are overlaid. FIG. 16 is a diagram for explaining a method for designing the pattern of the conductive mesh shown in FIG. 9 and a method for determining a generating point. FIG. 17 is a diagram for explaining a method of designing the pattern of the conductive mesh shown in FIG. 9, and is a diagram showing a method for determining a generating point. FIG. 18 is a diagram for explaining a method of designing the pattern of the conductive mesh shown in FIG. 9, and is a diagram showing a method for determining a generating point. 19A to 19D are diagrams showing the determined mother point group in the absolute coordinate system and the relative coordinate system, and are diagrams for explaining the degree of dispersion of the mother point group. FIG. 20 is a diagram for explaining a method of designing the pattern of the conductive mesh shown in FIG. 9 and showing a method of creating a Voronoi diagram from the determined mother point and determining the pattern. is there. FIG. 21 is a plan view showing a modification of the electromagnetic wave shielding material. FIG. 22 is a plan view for explaining the pattern of the conductive mesh of the electromagnetic wave shielding material according to the prior art. 23 is a plan view showing a state in which the optical member shown in FIG. 8 and the electromagnetic wave shielding material shown in FIG. 22 are overlapped. 24 is a plan view showing a state in which the electromagnetic wave shielding material shown in FIG. 22 and the image forming apparatus shown in FIG. 12 are overlaid. 25 is a plan view showing a state in which the optical member shown in FIG. 8, the electromagnetic wave shielding material shown in FIG. 22, and the image forming apparatus shown in FIG. 12 are overlaid.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual product.

  Further, the embodiments described below are examples in which the present invention is applied to an image display device configured as a plasma display device. However, the present invention is not limited to this example, and the present invention can be widely applied to various image display devices such as an image display device using a CRT or other applications.

  FIGS. 1-21 is a figure for demonstrating one Embodiment by this invention. Among these, FIG. 1 is a cross-sectional view showing the image display device in a cross section along a normal line direction to the display surface of the image display device. 2-8 is a figure for demonstrating the optical member (optical sheet) integrated in the image display apparatus. 9 and 10 are diagrams for explaining the electromagnetic wave shielding material (electromagnetic wave shielding sheet) incorporated in the image display device. FIG. 11 is a diagram illustrating a state in which the light shielding portion of the optical member and the conductive mesh of the electromagnetic wave shielding material are stacked. FIG. 12 is a diagram for explaining the pixel arrangement of the image forming apparatus. FIG. 13 is a diagram illustrating a state in which the light shielding portion of the optical member and the pixel array of the image forming apparatus are overlapped. FIG. 14 is a diagram illustrating a state in which the conductive mesh of the electromagnetic wave shielding material and the pixel array of the image forming apparatus are overlapped. FIG. 15 is a diagram illustrating a state in which the light shielding portion of the optical member, the conductive mesh of the electromagnetic wave shielding material, and the pixel array of the image forming apparatus are overlaid. 16-20 is a figure for demonstrating the method to determine the plane pattern of the electroconductive mesh of the electromagnetic wave shielding material shown by FIG. 9 and FIG.

  As shown in FIG. 1, the image display apparatus 10 includes an image forming apparatus 15 that can form an image, and a light output side (image observer side, hereinafter referred to as an image observer (side)) of the image forming apparatus 15. And a laminated body 20 that is also abbreviated as “side”). Therefore, the light emitting surface of the stacked body 20 forms the display surface (light emitting surface) 10 a of the image display device 10, and the observer observes the image formed by the image forming device 15 through the stacked body 20. Become.

In the illustrated example, the stacked body 20 is disposed in contact with the image forming apparatus 15. In this case, the laminate 20 may be joined to the image forming apparatus 15 by an adhesive (used to include a pressure-sensitive adhesive) or may simply be disposed on the image forming apparatus 15. Alternatively, unlike the illustrated example, the stacked body 20 may be disposed apart from the image forming apparatus 15. Further, when the laminate 20 is not joined to the image forming apparatus 15, the laminate 20 may include a support plate (support layer) having high rigidity such as a glass plate.
Note that “adhesion” as used in this specification includes “adhesion”.

  In the present embodiment, the image forming apparatus 15 is configured as a plasma display panel (PDP) corresponding to the configuration of the image display apparatus 10 as a plasma display apparatus. The PDP has two glass substrates, a discharge cell that defines an image between the two glass substrates, and the discharge cell is filled with a rare gas such as xenon. Visible light is generated for each pixel by generating plasma in the rare gas atmosphere and applying ultraviolet light generated at this time to the phosphor in each discharge cell. The image forming apparatus 15 configured as a PDP can form an image that can be observed from the image forming surface 15a by controlling light emission for each pixel.

  FIG. 12 discloses an example of a pixel array of the image forming apparatus (image display panel) 15. As shown in FIG. 12, one pixel P includes a sub-pixel (sub-pixel) RP that emits red light, a sub-pixel GP that emits green light, and a sub-pixel BP that emits blue light. That is, the image forming apparatus 15 can form an image in color. In the example shown in FIG. 12, the pixels P are formed as a so-called stripe arrangement. That is, the sub-pixel RP that emits red light, the sub-pixel GP that emits green light, and the sub-pixel BP that emits blue light are successively arranged in one direction (vertical direction in FIG. 12). On the other hand, the sub-pixel RP that emits red light, the sub-pixel GP that emits green light, and the sub-pixel BP that emits blue light are sequentially repeated one by one in a direction orthogonal to the one direction (the horizontal direction in FIG. 12). Are lined up. 12 shows the image forming apparatus 15 from the normal direction to the image forming surface (light-emitting surface) 15a of the image forming apparatus 15, that is, from the normal direction to the panel surface of the plasma display panel constituting the image forming apparatus 15. 15 shows the arrangement of the pixels P.

  The laminate 20 disposed on the light output side of the image forming apparatus 15 includes an optical member (optical sheet) 50 formed in a sheet shape and an electromagnetic wave shielding material (electromagnetic wave shielding sheet) 30 formed in a sheet shape. doing.

  The optical member 50 can transmit the image light from the image forming apparatus 15, and on the other hand, unnecessary light (typically ambient light such as illumination light or sunlight incident on the display device 10) ( (Outside light) is properly shielded. When the image display device 10 is arranged in a bright environment, the contrast of the display image is lowered by the ambient light incident on the image display device 10. In particular, in the image display device 10 using the PDP, the ambient light incident on the image display device 10 is reflected by the phosphor in the PDP, so that the contrast of the display image is remarkably lowered. The optical member 50 can contribute to improving the contrast of the display image by absorbing the ambient light incident on the image display device 10.

  Further, as described above, unnecessary electromagnetic waves are also emitted from the image forming apparatus 15. The electromagnetic wave shielding material 30 shields electromagnetic waves in the kHz to GHz band radiated from the image forming apparatus 15 (that is, “electromagnetic waves” here is a concept that does not include near infrared rays or ultraviolet rays), and , Function as a filter for transmitting visible light constituting the image.

  In the example shown in FIG. 1, the optical member 50 is located on the light output side of the electromagnetic wave shielding material 30. However, it is not restricted to this, The electromagnetic wave shielding material 30 may be arrange | positioned rather than the optical member 50 at the light emission side. The details of the optical member 50 and the electromagnetic wave shielding material 30 will be described later.

  In addition, the laminate 20 can include various functional layers laminated on the electromagnetic shielding material 30 and the optical member 50. The functional layer included in the stacked body 20 is appropriately selected according to the image forming apparatus 15 and has, for example, a filter function that blocks radiation in a specific wavelength range emitted from the image forming apparatus 15 including a plasma display panel. In other words, the layer may be a layer provided with an optical function, or a layer provided with other functions such as a protective function. More specifically, as a layer having a filter function, a layer having a function of absorbing near infrared rays, a layer having a function of absorbing neon light, a layer having a function of absorbing ultraviolet rays (UV), Examples thereof include a coloring filter function having an absorption spectrum in a specific wavelength range in visible light. In addition, the layer having an optical function includes an antireflection layer made of a low refractive index material layer such as magnesium fluoride, a fluorine resin to which hollow silica particles are added, and an antiglare layer made of an acrylic resin coating film to which silica particles are added. Examples of the layer having a protective function and the like include a hard coat layer, an impact resistant layer, an antifouling layer, and an antistatic layer.

  By the way, each layer contained in the laminated body 20 may be mutually joined using the adhesive agent. Moreover, you may make it provide one or more of various functions, such as a function which absorbs near infrared rays, a function which absorbs neon light, a function which absorbs an ultraviolet-ray (UV), to this adhesive agent.

  Here, FIG. 1A shows an example of a laminate 20 suitable particularly when the image forming apparatus is a PDP. In the laminate 20 shown in FIG. 1A, an antireflection layer 21, a transparent substrate 51, an optical functional layer 55, an ultraviolet absorber and an antioxidant (not shown) are sequentially added from the observer side. A transparent pressure-sensitive adhesive layer, a conductive mesh 40 having a blackened layer formed on the observer side surface, a transparent substrate 35, a near-infrared absorber (not shown), a neon light absorber, and a coloring pigment were added. Contains a transparent adhesive layer (this layer adheres to the PDP).

  In this specification, the “light exit side” refers to the downstream side (observer side, in FIG. 1) of the light traveling direction from the image forming apparatus 15 to the observer through the laminated body 20 without being folded back. Is the upper side of the page.

  Further, in the present specification, the terms “sheet”, “film”, and “plate” are not distinguished from each other only based on the difference in names.

  Furthermore, in this specification, the “sheet surface (film surface, plate surface, panel surface)” is the plane of the target sheet-like member when the target sheet-like member is viewed as a whole and globally. It refers to the surface that matches the (spread) direction. In the present invention, since each sheet-like member such as the optical member 50 is normally uniform in thickness distribution over the entire surface, the sheet surface of each sheet-like member is its front surface, back surface, or these. It means a (virtual) plane parallel to the front and back surfaces. In the present embodiment, the panel surface of the image forming apparatus 15, the light exit surface (image forming surface) 15 a of the image forming apparatus 15, the sheet surface of the sheet-like laminate 20, and the sheet of the sheet-like electromagnetic shielding material 30. The surface, the sheet surface of the sheet-like optical member 50, the display surface 10a of the image display device 10, and the like are parallel to each other.

  Furthermore, terms used in the present specification for specifying shapes and geometric conditions, for example, terms such as “parallel”, “orthogonal”, “triangle”, “trapezoid” and the like are not restricted to a strict meaning. Therefore, it should be interpreted including an allowable error to the extent that a similar function can be expected.

  Next, the optical member 50 will be further described in detail. As shown in FIG. 1 and FIG. 2, in the present embodiment, the optical member 50 includes a sheet-like transparent base material 51 and an optical functional layer 55 provided on the transparent base material 51. . In the example shown in FIGS. 1 and 2, the optical member 50 is disposed in the intermediate portion of the laminate 20, and the base 51 of the optical member 50 is disposed on the image forming apparatus 15 side. Yes. However, the optical member 50 may be disposed at a position other than the intermediate portion of the stacked body 20, for example, closest to the image forming apparatus 15. In the form shown in FIG. 1, the optical member 50 is arranged such that the optical functional layer 55 is located on the viewer side and the transparent substrate 51 is arranged on the image forming apparatus 15 side. This mode is preferable when the contrast improvement effect is more important. However, when the image viewing angle enlargement is more important, the optical functional layer 55 is positioned on the image forming apparatus 15 side and the transparent substrate 51 is positioned on the observer side as shown in FIG. 1A. Thus, the optical member 50 may be arranged.

  1 and 1A, the outermost surface of the laminate 20 on the observer side (the outermost surface of the transparent substrate 51 and the outermost surface of the image display device) has a low refractive index. An antireflection layer 21 composed of layers is provided. In order to prevent external light from being reflected in the surrounding scenery due to reflection of external light on the outermost surface of the laminate 20, such a form is preferable. However, of course, the antireflection layer 21 may be omitted when high external light reflection prevention performance is not required.

  The transparent substrate 51 is a layer that supports the optical functional layer 55 and is appropriately configured so as to have appropriate strength and appropriate transparency. As an example, the thickness of the transparent substrate 51 can be 20 μm to 200 μm. As such a transparent substrate 51, for example, a biaxially stretched polyethylene terephthalate (PET) film can be used. The biaxially stretched polyethylene terephthalate film is suitable for application as the transparent substrate 51 in that it has appropriate transparency and durability against ultraviolet irradiation treatment, heat treatment, and the like.

  The optical function layer 55 includes a plurality of light shielding portions 60 arranged at intervals. The light shielding portions 60 are arranged in a certain arrangement direction parallel to the layer surface of the optical function layer 55, and extend linearly in a direction intersecting with the arrangement direction. As shown in FIG. 8, in the present embodiment, the light shielding parts 60 are arranged in a stripe (parallel line group or stripe pattern) shape. That is, each light shielding portion 60 extends linearly in a direction orthogonal to the arrangement direction. In the present embodiment, the arrangement pitch P of the light shielding portions 60 is constant. Further, a light transmission part 56 is provided between two adjacent light shielding parts 60. In other words, the optical function layer 55 includes the light shielding portions 60 and the light transmitting portions 56 that are alternately arranged along the sheet surface of the optical member 50.

  From the viewpoint of making the moire caused by the interference between the period of the pixel P and the period of the light shielding part 60 inconspicuous, the longitudinal direction of the light shielding parts 60 arranged in a stripe shape is as shown in FIG. Is preferably tilted several degrees with respect to the arrangement direction of the pixels P. This inclination angle is called a bias angle (degree). Such an inclination is a technique that is widely used in general to make moire inconspicuous. The value of the bias angle that minimizes moiré changes depending on a plurality of factors such as the arrangement period of the pixels P and the light-shielding part 60, the width of the light-shielding part 60, and is usually 1 to 45 °, preferably 3 to 3. The range is 15 °.

  The light transmission part 56 is a part having a function of transmitting light, and is emitted from the image forming apparatus 15 as shown in FIG. 2, and is directed to the normal direction of the light exit surface 15a or a direction in the vicinity thereof. The traveling image light L21 can be transmitted. An observer can observe an image formed by the image forming apparatus 15 through the light transmission unit 56. The light shielding portion 60 is a portion having a function of absorbing light, and as shown in FIG. 2, the light L26 inclined from the normal direction to the sheet surface of the optical member 50, typically laminated from the observer side. It can absorb ambient light such as illumination light and sunlight incident on the body 20 and stray light in the image display device 10. As described above, the light shielding unit 60 absorbs unnecessary light L26 other than the image light incident on the image display apparatus 10 from the observer side, thereby effectively improving the contrast of the display image displayed by the image display apparatus 10. Can be made.

  The illustrated light shielding portion 60 includes a base material (binder portion) 61 and light absorbing particles 62 dispersed in the base material 61. The light absorbing particles 62 are particles having a function of absorbing visible light. Thereby, in the optical functional layer 55, the light absorbing particles 62 can absorb the light incident on the light shielding part 60 without being reflected at the interface between the light transmission part 56 and the light shielding part 60. In the optical functional layer 55 described here, the visible light absorption function of the light absorbing particles 62 causes light inclined from the normal direction of the optical member 50, typically unnecessary light such as ambient light and stray light. It is effectively absorbed and the contrast of the display image can be improved.

  Such light absorbing particles 62 are preferably light absorbing colored particles such as carbon black, but are not limited thereto, and have a specific wavelength according to the characteristics of light from the image forming apparatus 15. Colored particles that selectively absorb can be used. Specifically, carbon such as carbon black and graphite, pigments such as metal oxides such as black iron oxide and copper oxide, dyes such as aniline black, resin fine particles colored with these pigments or dyes, and colored glass Examples thereof include beads. In particular, colored resin fine particles are preferably used from the viewpoints of cost, quality, availability, etc. More specifically, crosslinked acrylic fine particles containing carbon black and crosslinked urethane fine particles containing carbon black Etc. are preferably used. Such light-absorbing particles can usually be contained in the composition that forms the light-shielding portion 60 in a range of 3% by mass to 30% by mass.

  The means for causing the light shielding unit 60 to exhibit the visible light absorption function is not limited to the method using the light absorbing particles 62. For example, the entire surface of the light shielding part 60 made of metal or resin may be colored with a pigment or a dye so that the light shielding part 60 exhibits the light absorbing function as a whole.

  In the example shown in FIG. 2 and FIG. 3, the light shielding portion 60 is in a cross section along the normal direction of the sheet surface of the optical member 50 and perpendicular to the extending direction of the light shielding portion 60, that is, the main cut surface. It has a triangular shape. On the other hand, the light transmission part 56 has a trapezoidal shape at the main cut surface. In the main cut surface of FIG. 4, the short upper base and the long lower bottom in the trapezoidal shape forming the light transmitting portion 56 are along the sheet surface of the optical member 50, and the long lower base in the trapezoidal cross section is It is located on the transparent substrate 51 side. Further, the side of the optical functional layer 55 that does not face the transparent substrate 51 is formed by the base in the triangular shape that forms the light shielding portion 60 and the short upper base in the trapezoidal shape that forms the light transmitting portion 56.

  In the example shown in FIGS. 2 and 3, the optical functional layer 55 has a transparent land portion (communication portion) 57 formed in a sheet shape, and the light shielding portion is formed on the land portion 57. 60 and the light transmission part 56 are supported. Such a land portion 57 can be integrally formed from the same material as that of the light transmission portion 56 due to, for example, a manufacturing method of the optical function layer 55 described later. However, the land portion 57 is not essential in the optical function layer 55. Therefore, the land portion 57 may be omitted, and the optical functional layer 55 may be formed only from the light shielding portion 60 and the light transmission portion 56.

  However, the main cut surface shapes of the light shielding unit 60 and the light transmitting unit 56 in the main cut surface along the normal direction of the optical member 530 are not limited to the examples shown in FIGS. As shown in FIG. 7, various changes are possible.

  In the aspect shown in FIG. 4, the cross-sectional shape of the light shielding part 60 is a trapezoidal shape. Specifically, the light-shielding portion 60 has a trapezoidal shape, particularly an isosceles trapezoidal shape, having an upper base and a lower base in which the cross-sectional shape is parallel, and two oblique sides connecting the upper base and the lower base.

  In the mode shown in FIG. 5, the trapezoidal or triangular hypotenuse (the interface between the light shielding portion 60 and the light transmitting portion 56) forming the light shielding portion 60 is composed of two sides instead of one side. Yes. That is, the hypotenuse that defines the light shielding portion 60 is formed in a polygonal line shape on the main cut surface. The angle formed by the hypotenuse on the lower base side of the substantially trapezoidal cross section or the hypotenuse on the base side of the substantially triangular cross section with respect to the normal direction to the sheet surface of the optical function layer 55 is θa1, and the upper base of the substantially trapezoidal cross section Assuming that the angle formed by the oblique side arranged on the apex side (substrate 31 side) of the oblique side of the side or the normal side to the sheet surface of the optical function layer 55 is θa2, the relationship of θa1> θa2 May be satisfied. In addition, the length Ha1 along the normal direction to the sheet surface of the optical function layer 55 of the hypotenuse on the lower base side of the substantially trapezoidal cross section or the hypotenuse on the base side in the substantially triangular cross section is the upper base of the substantially trapezoidal cross section. The oblique side on the side or the oblique side on the apex side of the substantially triangular section may be the same as the length Ha2 along the normal direction to the sheet surface of the optical function layer 55.

  Further, the present invention is not limited to the example shown in FIG. 5, and each hypotenuse (interface between the light shielding portion 60 and the light transmitting portion 56) in the substantially trapezoidal shape or the substantially triangular shape of the light shielding portion 60 is formed from three or more line segments. It may be formed as a broken line. Furthermore, each hypotenuse in the substantially trapezoidal cross-section or the substantially triangular cross-section of the light shielding part 60 may be configured as a curve as in the embodiment shown in FIG. Or the main cut surface shape which makes the light-shielding part 60 may be a rectangular shape like the aspect shown by FIG. That is, in the aspect shown in FIG. 7, the main cut surface shape of the light shielding portion 60 is parallel to the pair of sides extending in parallel with the sheet surface of the optical member 50 and the normal direction to the sheet surface of the optical member 50. And a pair of extending sides.

As a specific example of such a light transmission part 56 and the light shielding part 60, each dimension in the cross section along the normal line direction of the optical member 50 can be set as follows as an example. First, the maximum width Wmax of the light shielding portion 60, more strictly, the maximum width Wmax in a cross section orthogonal to the longitudinal direction of the boundary line segment can be set to 5 μm or more and 100 μm or less. Further, the height H of the light shielding portion 60 (the height of the light transmission portion 56) can be set to 20 μm or more and 200 μm or less. In consideration of the case where the optical functional layer 55 has the land portion 57, the total thickness T of the optical functional layer 55 and the height H of the light shielding portion 60 satisfy the relationship of 0.6T ≦ H ≦ T. Also good. Further, the arrangement pitch Pt of the light shielding portions 60 can be in the range of 5 to 200 μm. The relationship between the dimensions (arrangement pitch) of the pixels P and the arrangement pitch Pt of the light shielding portions 60 can be appropriately designed. For example, when the improvement of the image contrast in the presence of outside light is required rather than the improvement of the luminance of the image itself, the arrangement pitch Pt of the light shielding portions 60 is set to the smaller dimension TMIN of the vertical and horizontal dimensions of the pixel P. Set smaller than (size of one side if pixel is square),
Pt <T _MIN
It is preferable that On the other hand, in the case where the improvement of the brightness of the image itself is more important than the improvement of the image contrast in the presence of outside light, the arrangement pitch Pt of the light shielding portions 60 is set to the larger dimension T _MAX of the vertical and horizontal dimensions of the pixel P. (If the pixel is a square, the size of one side)
Pt ≧ T _MIN
It is preferable that

  In addition to ensuring a certain amount of unnecessary light absorption function by the light shielding unit 60, the optical function layer 55 (optical member 50) has a certain high visible light transmittance in order to transmit the image light from the image forming apparatus 15. There is a need to. Specifically, the width of the light shielding portion 60 and the light shielding portion are set so that the total ratio of the regions where the many light transmission portions 56 are closed (hereinafter also referred to as “aperture ratio”) is 50% or more and 90% or less. It is preferable to adjust the arrangement pitch Pt.

Furthermore, the refractive index of the material forming the light transmission part 56 and the refractive index of the material forming the light shielding part 60 can be appropriately selected. However, in the form in which the width of the light-shielding part 60 increases toward the observer as in the illustrated form, the refractive index Nb of the base material 61 of the light-shielding part 60 and the refraction of the material forming the light transmission part 56 The rate Np is designed to an appropriate value. First, the refractive index Nb of the base material 61 of the light shielding part 60 and the refractive index Np of the material forming the light transmission part 56;
Nb <Np
The following operational effects can be expected. As shown in FIG. 2, the component of the image light emitted from the image forming apparatus 15 that is observed by the observer and recognized as an image is mainly parallel to the normal line of the sheet surface of the optical material 50. It is almost parallel light. Therefore, L21 that passes through the light transmission part 56 without hitting the light shielding part 60 can pass through the optical function layer 55 without being absorbed. On the other hand, the image light L22 has an angle of travel with respect to the normal line of the slope defining the light shielding portion 60, that is, the incident angle exceeds the critical angle, and the interface between the light transmitting portion 56 and the light shielding portion 60. It can be totally reflected without being absorbed. This totally reflected image light L22 expands the range of the image light emission angle (angle with respect to the normal line of the display surface 10a), so that an appropriate viewing angle can be given to the display device 10.

  On the other hand, unnecessary light L26 such as sunlight is incident on the normal of the sheet surface of the optical member 50 from an oblique direction. For this reason, the incident light L26 has an incident angle with respect to the normal line of the inclined surface less than the critical angle, and is not totally reflected, and almost all of the incident light (usually about 95% of the incident light) enters the light shielding portion 60. Then, it can be absorbed by the light absorbing particles 62.

  As a result, when the refractive index Nb of the base material 61 of the light shielding part 60 is Nb <Np with respect to the refractive index Np of the material forming the light transmission part 56, the viewing angle is increased and the presence of external light is present. Both effects of improving image contrast can be achieved. In this respect, the angles θa, θa1 and θa2 formed by the interface between the light transmission part 56 and the light shielding part 60 with respect to the normal direction to the sheet surface of the optical member 50 are greater than 0 ° and 10 ° or less. It is preferable that the angle is greater than 0 ° and not greater than 6 °. In this case, the refractive index Nb of the base material 61 of the light shielding part 60 is preferably set to be smaller by 0.12 to 0.5 than the refractive index Np of the material forming the light transmission part 56.

Next, the refractive index Nb of the base material 61 of the light shielding portion 60 and the refractive index Np of the material forming the light transmitting portion 56;
Nb <Np
Will be described. Of the image light, L21 passing through the light transmitting portion 56 is transmitted without absorption of the wrinkles as in the above-described aspect. On the other hand, unlike the case of FIG. 2, L22 incident on the slope defining the light shielding portion 60 is not totally reflected at the interface between the light transmitting portion 56 and the light shielding portion 60 and is almost (usually 95 of the incident light). %) Absorbed. Therefore, it is possible to reduce (narrow) the image light emission angle range and limit the viewing angle of the image display device 10. On the other hand, the unnecessary light L26 such as sunlight almost penetrates into the light shielding part 60 and is absorbed by the light absorbing particles 62 without total reflection regardless of the incident angle with respect to the normal line of the inclined surface. As a result, both the effect of suppressing the viewing angle and the effect of improving the image contrast in the presence of outside light are exhibited. This form is suitable for personal use and for peeping prevention in an image display device for displaying secret information.

  Here, an example of a method for producing the optical member 50 as described above will be described. In the following description, the optical member 50 is produced by first forming the light transmission part 56 and then forming the light shielding part 60.

  First, the light transmission part 56 is composed of a light transmission part constituting composition that becomes a part of the light transmission part 56 by being cured, for example, an epoxy acrylate prepolymer having a characteristic of being cured by ionizing radiation such as electron beams and ultraviolet rays. Or the like. Specifically, a die roll having a convex portion corresponding to the configuration (arrangement, shape, etc.) of the light shielding portion 60, in other words, a die having a concave portion corresponding to the configuration (arrangement, shape, etc.) of the light transmission portion 56. Prepare the roll. A sheet to be the transparent substrate 51 is fed between the mold roll and the nip roll, and the light transmitting portion constituting composition is supplied between the mold roll and the transparent substrate 51 in accordance with the feeding of the sheet. Thereafter, the light transmitting portion constituting composition is pressed with the mold roll and the nip roll so that the liquid light transmitting portion constituting composition supplied on the transparent substrate 51 is filled in the concave portion of the mold roll in an uncured state. . At this time, by supplying the light transmitting portion constituting composition onto the transparent base 51 so as to be thicker than the depth of the concave portion of the mold roll, that is, so that the mold roll and the transparent base 51 do not come into contact with each other. The land portion 57 described above is formed integrally with the transparent resin portion 51 from the light transmission portion constituting composition. In this way, after filling the uncured and liquid light-transmitting part constituent composition between the transparent substrate 51 and the mold roll, the light-transmitting part constituent composition is cured (solidified) by irradiation with ionizing radiation. Thus, the light transmission part 56 can be formed.

  Next, the light-shielding part 60 is a light-absorbing particle having an average particle diameter of 1.5 μm, including urethane acrylate prepolymer having a characteristic of being cured by ionizing radiation that forms the base material 61 when cured, and carbon black. 62, and an uncured and liquid light absorbing part constituent composition. First, a light absorption part constituent composition is supplied on the light transmission part 56 formed previously. Then, while filling the groove formed between the adjacent light transmission parts 56, that is, the part corresponding to the convex part of the mold roll, using the doctor blade, The excess light absorbing portion constituting composition overflowing outside the groove is scraped off. Then, the light-shielding part 60 is formed by irradiating the light absorbing part constituting composition between the light-transmitting parts 56 with ionizing radiation and curing it. Thereby, the optical function which has the transparent base material 51, the land part 57 provided on the transparent base material 51, the light transmission part 56 provided on the land part 57, and the stripe-shaped light-shielding part 60. The optical member 50 including the layer 55 is produced.

  Next, the electromagnetic wave shielding material 30 will be described in further detail. As shown in FIG. 1, in the present embodiment, the electromagnetic wave shielding material 30 includes a sheet-like transparent base material 35 and a conductive mesh 40 provided on the transparent base material 35. In the example shown in FIG. 1, the electromagnetic wave shielding material 30 is disposed on the image forming apparatus 15 side of the laminate 20, and the base material 35 of the electromagnetic wave shielding material 30 is on the image forming apparatus 15 side. Has been placed. However, the electromagnetic shielding material 30 is not limited to this example, and the electromagnetic wave shielding material 30 may be disposed at a position other than the image forming apparatus 15 side in the stacked body 20. Further, the conductive mesh 40 of the electromagnetic wave shielding material 30 may be disposed on the image forming apparatus 15 side.

  The transparent substrate 35 is a layer that supports the conductive mesh 40 and is appropriately configured so as to have appropriate strength and appropriate transparency. As an example, the thickness of the transparent substrate 35 can be 20 μm to 150 μm, and the light transmittance of the transparent substrate 35 may be 80% or more. As such a transparent substrate 35, for example, a biaxially stretched polyethylene terephthalate (PET) film can be used. The biaxially stretched polyethylene terephthalate film is suitable for application as the transparent substrate 35 in that it has moderate transparency and durability against ultraviolet irradiation treatment, heat treatment, and the like. As another example, the thickness of the transparent substrate 35 can be 500 μm to 10000 μm (1 cm). As such a transparent material, for example, glass such as soda glass and potash glass, transparent ceramics such as PLZT, and a quartz plate can be used.

  As shown in FIGS. 9 and 10, the conductive mesh 40 for shielding electromagnetic waves is formed as a line portion 44 formed in a net shape that defines a large number of opening regions 42. The line portion 44 forming the conductive mesh 40 is grounded at a position (usually a peripheral portion) (not shown), whereby the conductive mesh 40 disposed at a position overlapping the light exit surface 15a of the image forming apparatus 15 is imaged. The electromagnetic wave from the forming device 15 is shielded.

In order to provide the electromagnetic wave shielding material 30 with a sufficient electromagnetic wave shielding function, the size of the opening area 42 per one is the same as that when the opening area 42 made of a conductor is approximated to a waveguide having a short depth.斷 The frequency F _CUT is equal to or higher than the maximum frequency F _{MAX of the} electromagnetic wave band to be shielded by the electromagnetic wave shielding material 30 (conductive mesh 40), that is,
F _CUT ≧ F _MAX
Set to be. First, for the sake of simplicity, when the shape of each opening region 42 is approximated to a square (rectangle) having a side length of A,
F _CUT = C / (2A)
It becomes. However, in this case, the calculation is performed assuming a fundamental mode having a minimum frequency among various modes that can travel in the waveguide. Therefore,
F _CUT = C / (2A) ≧ F _MAX
The relationship holds. However, C in the formula is the speed of light (about 3.0 × 10 ⁺⁸ m / s ² ). Than this,
C / (2F _MAX ) ≧ A
It becomes.

In the conductive mesh 40 described here, the actual shape of the individual opening regions 42 is not square but various in various ways, but is approximately the average of the circumscribed circle diameters of the opening regions 42 in the conductive mesh 40. It can be regarded as the length A _AVG of one side of the rectangular waveguide whose values are averaged. However, in order to reliably shield electromagnetic waves having a frequency below F _MAX in the entire opening region, individual A (distributed as the circumscribed circle diameter of the opening region) distributed in the range of A _{MIN to} A _MAX Since the maximum value A _MAX should be designed to satisfy C / (2F _MAX ),
C / (2F _MAX ) ≧ A _MAX
Thus, if the maximum frequency FMAX of the electromagnetic wave band to be shielded is determined, A _MAX is determined as the maximum value of the circumscribed circle diameter of the opening region 42. If FMAX = 100 GHz, A _MAX ≦ 1.5 mm, and A _MAX ≦ 1.0 mm may be designed with some allowance. In consideration of securing the transmittance of image light (brightness of the screen) (an aperture area ratio of a certain level or more) and the difficulty of microfabrication, at least about A _MIN ≧ 0.1 mm is necessary. From the above, assuming that the screen display application of the image display device is used, the average value A of the circumscribed circle diameter of the opening region 42 is 0.1 mm ≦ A _MIN ≦ A _MAX ≦ 1 mm, or 100 μm ≦ 1 μm. A _MIN ≦ A _MAX ≦ 1000 μm may be satisfied. Further, by replacing the values of此the _{A MIN} and _{A MAX} to the value (unit opening) area of the opening region 42, the average area of the opening region is preferably in the range of 0.01 mm ² or more 1 mm ² or less.

  In addition, in order to provide the electromagnetic wave shielding material 30 with a sufficient electromagnetic wave shielding function, it is necessary to reduce the surface resistance of the conductive mesh 40. At the same time, since the conductive mesh 40 is located on the image forming surface (light emitting surface) 15a of the image forming apparatus 15, it is also necessary to have a high visible light transmittance. Therefore, by adjusting the width of the line portion 44 that forms the conductive mesh 40 while adjusting the area of each opening region 42, high visible light transmission can be achieved while keeping the surface resistance of the conductive mesh 40 low. It is also possible to secure the rate. Specifically, an area in which many open areas 42 are closed on the image forming surface 15a of the image forming apparatus (image display panel) 15 while adjusting the area of each open area 42 to the above-described range. The line width of the line portion 44 is preferably set so that the total ratio (hereinafter also referred to as “aperture ratio”) is 50% or more and 95% or less. The specific line width is selected in the range of about 1 μm to 100 μm, preferably 5 μm to 50 μm.

Various designs are possible for the relationship between the average value A _AVG of the circumscribed circle diameter of the opening region 42 and the pixel P of the image display device. When it is desired to particularly reduce the shading unevenness of the conductive mesh, the average value A _AVG of the circumscribed circle diameter of the opening region 42 is determined as the smaller dimension T _MIN (pixel size) of the vertical and horizontal dimensions of the pixel P of the image display device. If it is a square, set it to be smaller than the dimension of any one side)
A _AVG <T _MIN
It is preferable that _Usually, the range of _{A AVG = 0.1 × T MIN ~0.7} × T MIN. When the brightness of the screen (visible light transmittance) and the invisibility of the line portion 44 are particularly obtained, the average value A of the circumscribed circle diameter of the opening region 42 is determined from the vertical and horizontal dimensions of the pixel P of the image display device. Set it to the larger dimension T _MAX (or one of the sides if the pixel is square) or more,
A _AVG ≧ T _MIN
It is preferable that _Usually, the range of _{A AVG = 1.3 × T MIN ~2.0} × T MIN.
Further, the arrangement pitch Pt of the light shielding portions 60, the smaller dimension T _MIN of the vertical and horizontal dimensions of the pixel P, the larger dimension T _MAX of the vertical and horizontal dimensions of the pixel P, and the average of the circumscribed circle diameter of the opening region 42 The relationship with the value A _AVG can also be appropriately designed according to the performance required for the image display device, the problem to be solved, and the like. For example,
Pt ≦ T _MIN ≦ T _MAX ≦ A _AVG
A _AVG ≦ T _MIN ≦ T _MAX ≦ Pt
T _MIN ≤ T _MAX ≤ Pt ≤ A _AVG
T _MIN ≦ T _MAX ≦ A _AVG ≦ Pt
Pt ≦ A _AVG ≦ T _MIN ≦ T _MAX
A _AVG ≦ Pt ≦ T _MIN ≦ T _MAX
T _MIN ≦ Pt ≦ A _AVG ≦ T _MAX
T _MIN ≤ A _AVG ≤ Pt ≤ T _MAX
Etc. can be designed.

The conductive mesh 40 as described above can be formed on the transparent substrate 35 by a conventionally known method such as the following (1) to (3).
(1) A method of laminating a conductive metal foil such as copper or aluminum on the transparent substrate 35 and etching the foil into a desired pattern.
(2) Conductive ink (for example, conductive ink in which conductive metal particles such as silver, copper, and nickel are dispersed in a resin binder such as acrylic resin and polyester resin) is formed on the transparent substrate 35 in a desired pattern. How to print. If necessary, a thin film of high conductivity metal such as copper, silver, gold, or nickel may be further formed on the pattern surface of the conductive ink by plating or the like in order to further improve the conductivity.
(3) Printing in a desired pattern on the transparent substrate 35 with ink containing an electroless plating catalyst such as palladium colloid particles in a resin binder, and copper, silver, gold on the surface of the printed pattern by an electroless plating method A thin film of high conductivity metal such as nickel is formed.
In addition, the surface of the conductive mesh 40 formed by these methods has a gold luster. Therefore, in order to more effectively develop the image contrast improvement effect by the optical member 50, it is preferable to form a blackened layer made of a light-absorbing substance on the observer side surface of the conductive mesh 40. The color tone of such a blackened layer is ideally black, but may be a low-lightness chromatic or achromatic color such as gray, brown, amber, rosy, dark green, or dark purple. The material constituting the blackened layer may be selected from known materials. For example, carbon black (black), black iron oxide, copper oxide, fine-particle copper-cobalt alloy, and the like can be used.

  Further, the pattern of the conductive mesh 40 when observed from the normal direction to the sheet surface of the sheet-like electromagnetic shielding material 30 will be described with reference mainly to FIGS. 9, 10, and 20.

  As shown in FIGS. 9, 10 and 20, the line portion 44 of the conductive mesh 40 includes a large number of branch points 46. The line portion 44 of the conductive mesh 40 is composed of a large number of boundary line segments 48 that form branch points 46 at both ends. That is, the line portion 44 of the conductive mesh 40 is composed of a large number of boundary line segments 48 extending between the two branch points 46. An opening region 42 is defined by connecting the boundary line segment 48 at the branch point 46. In other words, one opening region 42 is defined by being surrounded and divided by the boundary line segment 48.

  As shown in FIGS. 9, 10, and 20, since the line portion 44 is composed only of the boundary line segment 48, there is no line portion 44 that extends into the opening region 42 and becomes a dead end. In other words, there is no circuit that is disconnected and opened as an electric circuit, and all the line portions 44 constitute a closed circuit. As a result, when the entire line portion 44 is considered as a circuit network, the maximum electrical conductivity can be obtained with the same covering area ratio and thickness of the conductor. According to such an aspect, it is possible to effectively realize that the electromagnetic wave shielding material 30 is provided with a sufficient electromagnetic wave shielding function and a high visible light transmittance at the same time.

  By the way, as described above, when the optical member in which the light absorbing portions are repeatedly arranged and the electromagnetic shielding material having the conductive mesh are stacked in one laminated body, the periodicity of the light absorbing portion and the conductive mesh. In some cases, a striped pattern resulting from interference with the periodicity, that is, moire (interference fringes) is visually recognized. Further, when the optical member and the electromagnetic wave shielding material are arranged on the image forming apparatus, the complicatedness caused by the interference between the periodicity of the pixel arrangement, the periodicity of the light absorbing portion, and the periodicity of the conductive mesh. Moire is easily visible. When the moiré is visually recognized, the image quality of the image displayed on the image display device is significantly deteriorated.

  Here, FIG. 22 shows a conventional typical electromagnetic wave shielding sheet 130 having a conductive mesh 140 formed in a square lattice pattern. Further, in FIG. 23, an optical member 50 having a light shielding portion 60 in which the electromagnetic wave shielding sheet 130 having the conventional conductive mesh 140 shown in FIG. 22 is arranged in a stripe pattern shown in FIG. Overlapping state is shown. 24 shows a state where the electromagnetic wave shielding sheet 130 of FIG. 22 is arranged on the image forming apparatus 15 having the typical pixel arrangement shown in FIG. Further, FIG. 25 shows a state where the conventional electromagnetic wave shielding sheet 130 shown in FIG. 22 is arranged on the image forming apparatus 15 shown in FIG. 12 together with the optical member 50 shown in FIG. ing.

  As shown in FIG. 23 and FIG. 24, the conductive mesh 140 formed in a square lattice pattern includes the light shielding portion 60 of the optical member 50 arranged in a stripe pattern or the pixel arrangement of the image forming apparatus 15. When superposed, the stripes of light and darkness are caused by interference between the regular (periodic) pattern of the conductive mesh 140 and the regular (periodic) pattern of the light shielding portion 60 or the regular (periodic) pattern of the pixel P. It becomes visible. Further, as shown in FIG. 13, even when a slight moiré is visually recognized between the light shielding unit 60 having a stripe pattern and the pixel arrangement of the image forming apparatus 15, the conductive mesh 140 having a square lattice pattern has a stripe shape. By overlapping both the light shielding portion 60 and the pixel arrangement of the pattern, moire can be visually recognized more clearly. In this way, in the state of FIG. 25, the moire can be visually recognized more clearly because of the regularity (periodicity) of the conductive mesh 140, the regularity (periodicity) of the light shielding portion 60, and the rule of the pixel P. Not only the property (periodicity) but also the regularity (periodicity) of the striped pattern (moire) caused by the interference between the conductive mesh 140 and the light shielding portion 60 and the interference between the conductive mesh 140 and the pixel P It is thought that this is because the regularity (periodicity) of the striped pattern (moire) is added to cause new interference.

  In the example shown in FIGS. 23 to 25, the arrangement direction of the square lattice formed by the conductive mesh 140 is inclined by several degrees with respect to the arrangement direction of the pixels P and the arrangement direction of the light shielding portions 60. is doing. As described above, such an inclination is a technique that is widely used to make moire inconspicuous. However, in FIGS. 23 to 25, as can be understood from the fact that the remaining striped pattern is still visible, the degree of moire generation is not determined solely by the bias angle. It also depends on factors such as P, the ratio of the repetition period between the light shielding portion 60 and the conductive mesh 140, the line width of the conductive mesh 140 and the light shielding portion 60, and the like. In particular, when three or more elements arranged in a regular pattern are stacked, it becomes practically difficult to eliminate moiré with only the bias angle.

  On the other hand, in order to prevent the occurrence of moire, in the conductive mesh 40 of the electromagnetic wave shielding member 30 according to the present embodiment, there is no linear direction in which the opening regions 42 are arranged at a pitch having repetitive regularity (periodic). It is like that. As a result of intensive research, the present inventors do not simply make the pattern of the conductive mesh 40 irregular, but there is no direction in which the opening regions 42 of the conductive mesh 40 are arranged at a constant pitch. By defining the pattern of the conductive mesh 40 as described above, moire that may occur when the electromagnetic wave shielding material 30 is superimposed on the optical member 50 having the optical functional layer 55, and electromagnetic waves on the image forming apparatus 15 having the pixel arrangement. Moire that may occur when the shielding material 30 is stacked, and further, the electromagnetic wave shielding material 30 is superimposed on both the optical member 50 having the optical functional layer 55 and the image forming apparatus 15 having the pixel array as shown in FIG. It has been found that the moire that can occur in the case of the problem can be made ineffective and inconspicuous.

  Generally, it has been considered that making the pattern of the conductive mesh 40 irregular is effective for making the moire invisible. However, according to the study by the present inventors, even if the pattern shape and arrangement pitch of the conductive mesh 40 are simply made irregular, the moire cannot always be made sufficiently inconspicuous.

  For example, in the conductive mesh disclosed in Japanese Patent Laid-Open No. 11-121974 (the above-mentioned Patent Document 2), there is no periodicity in the Y-axis direction in the two-dimensional XY plane. As a result, the entire two-dimensional plane does not have a complete repetition cycle and can be visually recognized as an indefinite pattern. That is, by making the shape or arrangement pitch of the opening area partially irregular, the repeating regularity of the arrangement of the opening area can be specified at a constant repetition pitch in the vertical and horizontal directions. As compared with the square lattice arrangement of FIG. 22 arranged in the linear direction, the conductive mesh itself can be visually recognized as an irregular pattern as a whole. However, in the conductive mesh visually recognized as the irregular pattern, it has not been possible to prevent the occurrence of moiré to the extent that it can be perceived. The reason why the moire cannot be made inconspicuous effectively is considered to be because it still has a repetition cycle in the X-axis direction. That is, if a partial periodicity remains in any direction in the XY plane even partially, it is considered that moire occurs due to the residual periodicity.

  In addition, as in WO2007 / 114076 (Patent Document 1 described above), each unit opening region has a completely irregular pattern in both the X-axis direction and the Y-axis direction in the two-dimensional XY plane. If this is done, moire can be eliminated. However, when such a completely irregular pattern is adopted, a new problem occurs. That is, because the shape and area of each opening region are not uniform, when the entire conductive mesh is viewed, unevenness in shading is conspicuous in the appearance of the conductive mesh itself. This is a drawback in applications that are installed on the screen of an image display device. In addition to this, as a result of the line portions constituting the mesh being randomly arranged, there is a portion where the tip of the line portion is disconnected without being connected to other line portions and opened as a circuit. As a result, the electrical conductivity of the entire conductive mesh is lowered. The presence of such a broken portion not only contributes to the improvement of electric conductivity, but also causes a decrease in visible light transmittance, which is a major drawback as an electromagnetic wave shielding material.

  On the other hand, like the plane pattern of the conductive mesh 40 according to the present embodiment described here, the light-shielding mesh is such that there is no linear direction in which the open regions 42 (closed circuit) are arranged at a constant pitch. 40, and the constraint condition is imposed on the average number of boundary line segments 48 extending from one branch point 46 as follows, so that the occurrence of moire can be effectively prevented. At the same time, it has also become possible to effectively prevent the occurrence of uneven density. Such an operational effect can be said to be a remarkable effect that exceeds the expected range from the conventional state of the art that has simply implemented pattern irregularity as invisibility of moire.

  Here, FIG. 10 is a plan view for explaining that there is no direction in which a large number of opening regions 42 defined by the conductive mesh 40 are arranged at a constant pitch. In FIG. 10, on the sheet surface of the electromagnetic wave shielding material 30, one virtual straight line di that is arbitrarily oriented at an arbitrary position is selected. This single straight line di intersects with the boundary line segment 48 of the line portion 42 to form an intersection. These intersections are shown as intersections c1, c2, c3,..., C9 in order from the lower left side of the drawing. The distance between adjacent intersections, for example, the intersection c1 and the intersection c2, is the dimension t1 on the straight line di of the certain opening region 42. Next, the dimension t2 on the straight line di is similarly determined for another open area 42 adjacent to the open area 42 having the dimension t1 along the straight line di. Then, with respect to a straight line di in an arbitrary direction at an arbitrary position, from a boundary line segment 48 intersecting with the straight line di, a large number of opening regions 42 that encounter the straight line di in an arbitrary direction at an arbitrary position are as dimensions on the straight line di. t1, t2, t3,..., t8 are determined. And the sequence of numerical values of t1, t2, t3,..., T8 has no periodicity. In FIG. 10, t1, t2, t3,..., T8 are drawn separately from the conductive mesh 40 along with the straight line di in the lower part of the drawing for easy understanding. When the straight line di is rotated by an arbitrary angle from the one shown in FIG. 10 and the dimensions t1, t2,... Of each opening region A are obtained in another direction, as in the case of FIG. On the other hand, there is no repetitive periodicity. That is, there is no direction having a repetition period in the opening region 42 defined by the boundary line segment 48 as in the numerical values t1, t2, t3,. The fact that there is no direction in which the opening area 42 has a repetition period in this way is expressed that there is no direction in which the opening areas 42 are arranged at a constant pitch.

  In addition, in the conductive mesh 40 of the electromagnetic wave shielding member 30 according to the present embodiment, the average number of boundary line segments 48 extending from one branch point 46 is 3.0 or more and less than 4.0. In this way, when the average number of boundary line segments 48 extending from one branch point 46 is 3.0 or more and less than 4.0, the arrangement pattern of the conductive mesh 40 is represented by the square shown in FIG. The pattern can be greatly different from the lattice arrangement. When the average number of boundary line segments 48 extending from one branch point 46 is greater than 3.0 and less than 4.0, the pattern can be greatly different from the honeycomb arrangement. As a result of extensive research conducted by the present inventors, when the average number of boundary line segments 48 extending from one branch point 46 is 3.0 or more and less than 4.0, the arrangement of the open regions 42 is unsatisfactory. It is possible to make regular and prevent the direction in which the opening regions 42 are arranged with repetition regularity (periodicity) from being stably present, and as a result, moire is very inconspicuous effectively. Was confirmed to be possible.

  The average number of boundary line segments 48 extending from one branch point 46 is strictly determined by examining the number of boundary line segments 48 extending for all the branch points 46 included in the conductive mesh 40. The average value is calculated. However, in actuality, it extends from one branch point 46 in consideration of the size of the opening area 42 per line defined by the line portion 44 and the like. A section having an area expected to reflect the overall trend of the number of boundary segments 48 (for example, 10 mm × 10 mm in a conductive mesh in which the opening region 42 is formed in the above-described dimension example) The number of boundary line segments 48 extending for the branch points 46 included in the portion) is examined to calculate the average value, and the calculated value is the boundary line segment 48 extending from one branch point 46 for the conductive mesh. Average number of It may be treated as.

  Actually, in the conductive mesh 40 of the electromagnetic wave shielding material 30 shown in FIG. 9, the average number of boundary line segments 48 extending from one branch point 46 is larger than 3.0 and smaller than 4.0. . More specifically, when the number of boundary line segments 48 is confirmed for 387 branch points 46, there are 373 branch points 46 from which three boundary line segments 48 extend, and the other 14 branch points. Four boundary line segments 48 extend from the point 46, and the average number of branch lines at one branch point is 3.04.

  In FIG. 11, the electromagnetic wave shielding material 30 having the conductive mesh 40 shown in FIG. 9 is overlapped with the optical member 50 having the light shielding portions 60 arranged in the stripe pattern shown in FIG. The state is shown. Further, FIG. 14 shows a state where the electromagnetic wave shielding material 30 of FIG. 9 is arranged on the image forming apparatus 15 having the typical pixel arrangement shown in FIG. Further, FIG. 15 shows a state in which the electromagnetic wave shielding material 30 of FIG. 9 is disposed on the image forming apparatus 15 shown in FIG. 12 together with the optical member 50 shown in FIG.

  As can be understood from FIG. 11, when the conductive mesh 40 shown in FIG. 9 is actually produced and the laminated body 20 is produced together with the optical member 50 having the optical functional layer 55, the laminated body 20 includes A striped pattern that can be visually recognized, that is, moire (interference fringes) did not occur. Further, as can be understood from FIG. 14, when the conductive mesh 40 shown in FIG. 9 is actually manufactured and arranged on the pixel array of the image forming apparatus 15, a striped pattern that can be visually recognized, That is, moire (interference fringes) did not occur. Further, as can be understood from FIG. 15, when the stacked body 20 including the conductive mesh 40 shown in FIG. 9 is actually arranged on the pixel array of the image forming apparatus 15, the striped shape is visible to the extent that it can be visually recognized. A pattern, that is, moire (interference fringes) did not occur.

  Furthermore, the present inventors have found that although the mechanism is unclear, moire generated between other members can be made inconspicuous by using the electromagnetic wave shielding material 30 described here. As shown in FIG. 13, when the optical member 50 shown in FIG. 8 and the image forming apparatus 15 shown in FIG. On the other hand, as shown in FIG. 15, in addition to the optical member 50 shown in FIG. 8 and the image forming apparatus 15 shown in FIG. 12, the electromagnetic wave shielding material 30 shown in FIG. Even the moire that was visible until then is no longer visible. That is, according to the electromagnetic wave shielding material 30, not only does the moire caused by the electromagnetic wave shielding material 30 not occur or become inconspicuous, but also moire that may occur between other members can be made invisible. For example, when the moire cannot be made invisible only by adjusting the bias angle as described above, by using the electromagnetic wave shielding material 30, the desired function of the other member is maintained without changing the design of the other member. However, the moire problem caused by other members can also be solved. Such an effect of the electromagnetic wave shielding material 30 is a remarkable effect exceeding the range expected from the conventional technical level.

  Here, the average of the number of boundary line segments 48 extending from one branch point 46 is greater than 3.0 and less than 4.0, and there is no conductivity in which there is no linear direction in which the open regions 42 are arranged at a constant pitch. An example of a method for producing a mesh pattern will be described below.

  The method described below includes a step of determining a generating point, a step of creating a Voronoi diagram from the determined generating point, and a boundary segment extending between two Voronoi points connected by one Voronoi boundary in the Voronoi diagram. And determining the pattern of the conductive mesh 40 (line part 44) by determining the thickness of the determined path to define each boundary line segment. Hereinafter, each step will be described in order. The pattern shown in FIG. 9 described above is a pattern actually determined by the method described below.

  First, the process of determining a generating point will be described. First, as shown in FIG. 16, a first generating point (hereinafter referred to as “first generating point”) BP1 is arranged at an arbitrary position in the absolute coordinate system XY. The absolute coordinate system referred to here is a normal two-dimensional space (plane), but is particularly called an absolute coordinate system in order to distinguish it from a relative coordinate system described later. Next, as shown in FIG. 17, the second generating point BP2 is arranged at an arbitrary position separated from the first generating point BP1 by a distance r. In other words, the second generating point can be placed at an arbitrary position on the circumference of the radius r (hereinafter referred to as “first circumference”) located on the absolute coordinate system XY around the first generating point BP1. BP2 is arranged. Next, as shown in FIG. 18, the third generating point BP3 is arranged at an arbitrary position away from the first generating point BP1 by a distance r and from the second generating point BP2 by a distance r or more. Thereafter, the fourth generating point is arranged at an arbitrary position separated from the first generating point BP1 by the distance r and from the other generating points BP2 and BP3 by the distance r or more.

  In this way, the mother point is arranged at an arbitrary position away from the first mother point BP1 by the distance r and away from the other mother points until the next mother point cannot be arranged. Go. Thereafter, this operation is continued based on the second generating point BP2. That is, the next generating point is arranged at an arbitrary position separated from the second generating point BP2 by the distance r and from the other generating points by the distance r or more. Based on the second generating point BP2, until the next generating point cannot be arranged, it is at an arbitrary position away from the second generating point BP2 by the distance r and from the other generating points by the distance r or more. Place the mother point. Thereafter, the base point as a reference is sequentially changed, and the base point is formed in the same procedure.

  With the above procedure, the mother point is arranged until the mother point cannot be arranged in the region where the conductive mesh 40 is to be formed. When the generating point cannot be arranged in the region where the conductive mesh 40 is to be formed, the step of generating the generating point ends. By the processing so far, the mother point group irregularly arranged on the two-dimensional plane (XY plane) is uniformly dispersed in the region where the conductive mesh 40 is to be formed.

With respect to the generating point groups BP1, BP2,..., BP6 (see FIG. 19A) distributed in the two-dimensional plane (XY plane) in such a process, the distance between each generating point is not constant. Have a distribution. However, the range between any distribution completely random distribution of distances between two adjacent base points (uniformly distributed) but without the upper limit value R _MAX and the lower limit value R _MIN across the mean value R _AVG [Delta] R = It is distributed in R _MAX -R _MIN . It should be noted that here, although two adjacent generating points are created, if two Voronoi regions XA are adjacent after creating a Voronoi diagram to be described later from the generating point groups BP1, BP2,. It is defined that the generating points of the area XA are adjacent to each other.

That is, with respect to the generating point group described here, a coordinate system having each generating point as an origin (referred to as a relative coordinate system oxy), on the other hand, an actual two-dimensional plane (coordinate system) is absolute as described above. 16 (B), FIG. 16 (C),..., Which plots all generating points adjacent to the generating point placed on the origin on the coordinate system O-XY). Ask for. When the graphs of adjacent generating points on all the relative coordinate systems are displayed with the origin o of each relative coordinate system superimposed, a graph as shown in FIG. 16D is obtained. The distribution pattern of adjacent mother point groups on such a relative coordinate system is not a uniform distribution in which the distance between any two adjacent mother points constituting the mother point group is 0 to infinity, but R _AVG -ΔR To R _AVG + ΔR (meaning a donut-shaped region from radius R _MIN to R _MAX ).

  Thus, by setting the distance between each generating point, the Voronoi area XA obtained from the generating point group by the method described below, and the circumscribed circle diameter (or the opening area) of the opening area 42 obtained therefrom are used. Also, the distribution of the area is not a uniform distribution (completely random) but a distribution within a finite range.

  Note that, in the above-described step of determining the generating point, the size of the opening region 42 per one can be adjusted by changing the size of the distance r. Specifically, by reducing the size of the distance r, it is possible to reduce the size of the opening area 42 per one, and conversely by increasing the size of the distance r, The size of the opening region 42 can be increased.

  Next, as shown in FIG. 20, a Voronoi diagram is created based on the arranged generating points. As shown in FIG. 20, a Voronoi diagram is a diagram composed of line segments that are drawn at a perpendicular bisector between two adjacent generating points and are connected at the intersections of the bisectors. . Here, the line segment of the bisector is called Voronoi boundary XB, the intersection of Voronoi boundary XB forming the end of Voronoi boundary XB is called Voronoi point XP, and the area surrounded by Voronoi boundary XB is Voronoi area XA Call it.

  In the Voronoi diagram created as shown in FIG. 20, each Voronoi point XP forms a branch point 46 of the conductive mesh 40. Then, one boundary line segment 48 is provided between two Voronoi points XP forming the end of one Voronoi boundary XB. At this time, the boundary line segment 48 may be determined so as to extend linearly between the two Voronoi points XP as in the example shown in FIG. Various paths (for example, circle (arc), ellipse (arc), fence line, hyperbola, sine curve, hyperbolic sine curve, elliptic function curve, Bessel function curve, etc.) between the two Voronoi points XP without It may be extended by a broken line or the like. In addition, as in the example shown in FIG. 9, when the boundary line segment 48 is determined to connect the Voronoi points XP in a straight line, each Voronoi boundary XB defines the boundary line segment 48. become.

  After determining the path of each boundary line segment 48, the line width (thickness) of each boundary line segment 48 is determined. The line width of the boundary line segment 48 is determined, for example, so that the aperture ratio is in the above-described range, that is, the conductive mesh 40 exhibits desired electrical conductivity and visible light transmittance. As described above, the pattern of the conductive mesh 40 can be determined.

  According to the present embodiment as described above, the conductive mesh 40 of the electromagnetic wave shielding material 30 is formed from a large number of boundary line segments 48 extending between the two branch points 46 and defining the opening region 42. The average number of boundary line segments 48 extending from one branch point 46 is 3.0 or more and less than 4.0, and the opening regions 42 are arranged at a constant pitch, that is, at a constant repetition pitch. The specified direction does not exist. As a result, a striped pattern (moire, interference fringes) can be visually recognized in the laminate 20 in which the electromagnetic wave shielding material 30 is superimposed on the optical member 50 including a plurality of light shielding portions 60 arranged at intervals. Can be effectively prevented. Furthermore, even if this stacked body 20 is superimposed on the image forming apparatus 15 in which the pixels P are regularly (periodically) arranged, the stripe-like pattern (moire, interference fringes) is generated to such an extent that it can be visually recognized. Can be effectively prevented.

  Note that various modifications can be made to the above-described embodiment.

  For example, in the above-described embodiment, an example in which the average number of boundary line segments 48 extending from one branch point 46 is 3.0 or more and less than 4.0, or a boundary line extending from one branch point 46. Although the example in which the average of the number of minutes 48 is greater than 3.0 and less than 4.0 is shown, the present invention is not limited to these examples, and the average number of boundary line segments 48 extending from one branch point 46 is 3. It may be 0. When the average number of boundary line segments 48 extending from one branch point 46 is 3.0, the irregularly arranged opening regions 42 are more uniform in the region where the conductive mesh 40 is formed. In this way, it is possible to improve the electromagnetic wave shielding efficiency and more effectively prevent the occurrence of shading unevenness.

  In the above-described embodiment, the example in which the boundary line segment 48 of the conductive mesh 40 is formed in a straight line has been described, but the present invention is not limited to this. The boundary line segment 48 may extend between the two branch points 46 as described above along various paths such as a curved line.

  Furthermore, the pattern design method for the conductive mesh 40 described above is merely an example. For example, the mother point may be arranged in the following procedure. First, as in FIG. 16, the first generating point BP1 is arranged at an arbitrary position in the absolute coordinate system XY. Next, the second mother BP2 is arranged at an arbitrary position away from the first mother point BP1 by a distance r or more. Thereafter, the third generating point BP3 is arranged at an arbitrary position away from each of the first generating point BP1 and the second generating point BP2 by a distance r or more. Thereafter, the next mother point is sequentially arranged at an arbitrary position separated from the already arranged mother points by a distance r or more. With the above procedure, the mother point is arranged until the mother point cannot be arranged in the region where the conductive mesh 40 is to be formed. When the generating point cannot be arranged in the region where the conductive mesh 40 is to be formed, the step of generating the generating point ends. Even with such processing, irregularly arranged genera points can be uniformly dispersed in the region where the conductive mesh 40 is to be formed.

  Furthermore, in the pattern design method for the light-shielding mesh 40 described above, an example in which a specific generating point is first drawn in a plane and then a pattern of the conductive mesh 40 is formed as a Voronoi division pattern of the generating point. However, the present invention is not limited to this. For example, by manually drawing pentagonal and hexagonal opening regions 42 having different sizes and shapes in a plane, each of them is randomly drawn without any repetition cycle in any direction. The pattern of the light-shielding mesh 40 may be drawn by drawing such that the size (area or circumscribed circle diameter) of the square and hexagon falls within a predetermined range.

  Further, in the above-described embodiment, the example in which the direction in which the opening regions 42 are arranged at a constant pitch does not exist in the entire region of the conductive mesh 40 of the electromagnetic wave shielding material 30 has been described. However, in a partial region of the conductive mesh 40 of the electromagnetic wave shielding material 30, the average number of boundary line segments 48 extending from one branch point 46 is 3.0 or more and less than 4.0, and the opening region 42 is A pattern in which there is no direction arranged at a constant pitch may be formed.

  As a typical modification, an area (unit mesh area) S in which a plurality of opening areas 42 are arranged in a predetermined pattern without repeating periodicity (unit mesh area) S is prepared. Thus, the entire region of the conductive mesh 40 may be configured. That is, in this embodiment, the entire region of the conductive mesh 40 includes two or more unit mesh regions S in which the opening region groups 42 are arranged in the same pattern when viewed locally. become. Even in this case, the occurrence of moire is substantially inconspicuous and can be ignored unless there are four or more repetitions in a certain period in a specific direction. In this example, the pattern of the conductive mesh in one region S can be created in the same manner as the pattern creation method described with reference to FIGS. In particular, recently, the display surface 10a of the image display device 10 has been increased in size as represented by a plasma display device. In particular, for such a large image display device, the conductive mesh 40 is composed of an array of a plurality of unit mesh regions S, and each unit mesh region S has the same pattern. The configuration in which the opening regions 42 are arranged is preferable in that the pattern creation of the conductive mesh 40 can be greatly facilitated. In this case, the number of the opening regions 42 included in the unit mesh region S is preferably as large as possible in order to make it difficult to visually recognize the repetition of the unit mesh region S. Usually, the number of opening regions 42 included in the unit mesh region S can be 300 or more, preferably 500 or more.

  In the example shown in FIG. 21, the electromagnetic shielding material 30 is divided into six unit mesh regions S having the same shape, and the conductive mesh 40 is configured identically in each region R. The six regions R are arranged so that three regions are arranged in the vertical direction of FIG. 21 and two regions are arranged in the horizontal direction of FIG.

  In such a modification, for example, as shown in FIG. 21, if a plurality of regions S in which the arrangement of the opening regions 42 is arranged in the same pattern are regularly arranged, In FIG. 8, the range in which the opening regions 42 are arranged in a fixed arrangement repeatedly exists in the direction parallel to the arrangement direction of the corresponding regions, as many as the number of unit mesh regions S. That is, in the conductive mesh 40, there is a linear direction in which the opening regions 42 are arranged at a predetermined repetition pitch. In this case, due to the regular arrangement of the regions S, there is a concern that striped patterns (moire, interference fringes) or shading unevenness may occur. However, if the same unit mesh region S is repeated in three or less places, more preferably 2 or less places in a specific direction, such a striped pattern or shading unevenness can be ignored. This is not only because the number of repetitions is small, but also because the size of the region S is significantly different from the pixel size, so that it is substantially out of the relationship that causes moire. That is, as shown in FIG. 21, when a plurality of unit regions S are arranged in a certain direction at a predetermined pitch SP1, SP2, the predetermined pitch SP1, SP2 is a dimension of the image forming apparatus along a certain direction. It is preferably 1/3 or more of L1 and L2, more preferably 1/2 or more of dimensions L1 and L2 of the image forming apparatus along a certain direction.

  In the embodiment shown in FIG. 21, the unit mesh area S is arranged in two areas in the left-right direction and three areas in the up-down direction in one screen. However, the modification processing of the seam at the boundary between adjacent unit mesh regions (the deformation of the pattern that makes the seam inconspicuous, the modification processing), the shape of the unit mesh region (in FIG. 21, a rectangle, but other triangles, Hexagonal shape and other shapes are also possible), arrangement style (in Fig. 21, rectangular unit mesh areas are arranged vertically and horizontally on the grid, but even if the unit mesh area is rectangular, this is like brickwork. Depending on the contrivances such as arrangement), if the vertical and horizontal arrangement pitches SP1 and SP2 of the unit mesh area S are 1/10 or more, the striped pattern and the shading unevenness may not be noticeable. It has been found that this is possible.

(Combination with coloring filter)
The electromagnetic wave shielding material 30 using the specific conductive mesh 40 according to the present invention substantially does not cause moire between the pixel P and the stripe light shielding part 60 and does not cause unevenness in density. However, although the cause is currently unknown, when it is installed on the light exit surface of the image forming apparatus 15, a fine flicker may occur in the image depending on the conditions. In order to make such flickering inconspicuous, it is effective to laminate a colored filter having an absorption spectrum in a specific wavelength region in visible light at an appropriate position in the laminate 20 of the present invention. The coloring filter may be an achromatic color (black to gray) or a chromatic color (blue, brown, green, etc.), but an achromatic color that has little influence on the color of the image is preferred.

(Use)
The laminate 20 described above can be used for various applications. In particular, a plasma display (PDP) device used for a display unit of a television receiver, various measuring instruments and instruments, various office equipment, various medical equipment, computer equipment, telephones, electric signboards, various game machines, etc., a cathode ray tube It is suitable for a front filter of an image display device such as a display (CRT) device, a liquid crystal display device (LCD), and an electroluminescent display (EL) device, and particularly suitable for a plasma display device. In addition, it is used in addition to windows of various home appliances such as windows of buildings such as houses, schools, hospitals, offices, stores, vehicles, vehicles, airplanes, ships, etc. It can also be used for use as a laminate.

DESCRIPTION OF SYMBOLS 10 Image display apparatus 10a Display surface 15 Image formation apparatus, Image display panel 15a Light emission surface, Image formation surface 20 Laminated body 30 Electromagnetic wave shielding material, electromagnetic wave shielding sheet 35 Base material, transparent base material 40 Conductive mesh 42 Opening area 44 Line part 46 Branching point 48 Boundary line segment 50 Optical member, optical sheet 51 Base material, transparent base material 55 Optical functional layer 56 Transparent resin part, light transmission part 57 Land part, communication part 60 Light shielding part 61 Base material, binder part 62 Light absorption Particle XA Voronoi region XB Voronoi boundary XP Voronoi point

Claims (5)

An optical member including a plurality of light shielding portions arranged at intervals, and
An electromagnetic shielding material having a conductive mesh that defines a large number of opening regions, and
The conductive mesh is formed from a number of boundary segments that extend between two branch points to define the open area;
The conductive mesh has a pattern in which an average number of boundary line segments extending from one branch point is 3.0 or more and less than 4.0 and there is no direction in which the opening regions are arranged at a constant pitch. A laminate including a region to be formed.   The laminate according to claim 1, wherein the average of the number of boundary line segments connected at one branch point is greater than 3.0 in the region.   The laminate according to claim 1, wherein the average of the number of boundary line segments connected at one branch point is 3.0 in the region.   The said electromagnetic wave shielding material is a laminated body as described in any one of Claims 1-3 which further has a transparent base material which supports the said electroconductive mesh. An image forming apparatus;
An image display device comprising: the laminate according to any one of claims 1 to 4 provided on the image forming device.

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