JP6136517B2 - Conductive mesh, conductive mesh sheet, touch panel device and image display device - Google Patents

Description

  The present invention relates to a conductive mesh that defines a large number of open regions, and more particularly to a conductive mesh that can be effectively prevented from being visually recognized. The present invention also relates to a conductive mesh sheet having the conductive mesh, a touch panel device, and an image display device.

  Conventionally, a conductive mesh having visible light permeability has been widely used in various fields, for example, as an electromagnetic wave shielding material (electromagnetic wave shielding sheet) disclosed in Patent Documents 1 and 2 and a touch panel sensor. While such a conductive mesh is formed by using an opaque metal material, it is used as an electromagnetic wave shielding material (electromagnetic wave shielding sheet) or a touch panel sensor used in many applications, for example, a display device. In such applications, it is desired to be sufficiently invisible. In particular, when the pattern of the conductive mesh is visually recognized, not only does the transmittance decrease, but also causes problems such as shading, flickering, and moire when superimposed on other members, for example.

JP-A-11-121974 WO2007 / 114076

  The present invention has been made in consideration of the above points, and a conductive mesh effectively prevented from being visually recognized, and a conductive mesh sheet including the conductive mesh, a touch panel device, and an image. An object is to provide a display device.

The conductive mesh according to the present invention is:
Comprising a conductor defining a number of open areas;
The average line width of the conductor is 5 nm or more and 500 nm or less,
The average interval between adjacent opening regions is 1000 nm or less.

The first conductive mesh sheet according to the present invention is:
A conductive mesh according to the invention as described above;
A transparent base material that supports the conductive mesh.

The second conductive mesh sheet according to the present invention is:
An uneven structure layer having an uneven surface formed by minute protrusions;
A conductive mesh formed by a conductor extending along the bottom of the concave-convex surface of the concave-convex structure layer between the microprotrusions, and
The average line width of the conductor is 5 nm or more and 500 nm or less,
The average interval between adjacent microprotrusions is 1000 nm or less.

  The touch panel device according to the present invention includes either the conductive mesh or the conductive mesh sheet according to the present invention described above.

  The image display device according to the present invention includes any one of the above-described conductive mesh and conductive mesh sheet according to the present invention.

  According to the present invention, it is possible to effectively prevent the conductive mesh from being visually recognized. As a result, it is possible to effectively make inconspicuous defects such as shading, flickering, and moire caused by the visual recognition of the conductive mesh.

FIG. 1 is a diagram for explaining an embodiment of the present invention, and is a plan view showing an example of a conductive mesh pattern. FIG. 2 is a cross-sectional view along the normal direction of a conductive mesh sheet having a conductive mesh. FIG. 3 is a diagram showing a display device including an electromagnetic wave shielding sheet made of a conductive mesh sheet. FIG. 4 is a schematic diagram showing a touch panel device including a touch panel sensor made of a conductive mesh sheet. FIG. 5 is a perspective view showing an uneven structure layer of the conductive mesh sheet of FIG. FIG. 6 is a plan photograph showing an example of the uneven surface of the uneven structure layer. FIG. 7 is a plan photograph showing an example of the uneven surface of the uneven structure layer. FIG. 8 is a plan photograph showing an example of the uneven surface of the uneven structure layer. FIG. 9 is a graph showing the results of investigating the distribution of the spacing between adjacent minute protrusions on the uneven surface of the uneven structure layer of FIGS. FIG. 10 is a graph showing the results of examining the height distribution of the fine protrusions on the uneven surface of the uneven structure layer of FIGS. FIG. 11 is a diagram for explaining an example of a method for manufacturing the concavo-convex structure layer. FIG. 12 is a perspective view showing a roll plate used in the manufacturing method of FIG. FIG. 13 is a diagram for explaining a method of manufacturing the roll plate of FIG. FIG. 14 is a cross-sectional view showing still another example of the uneven surface of the uneven structure layer.

  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.

  In the present specification, the terms “plate”, “sheet”, and “film” are not distinguished from each other only based on the difference in names. For example, “sheet” is a concept that includes a member that can be called a plate or a film. Therefore, “conductive mesh sheet” is called a member called “conductive mesh plate” or “conductive mesh film”. It cannot be distinguished only by the difference.

  Furthermore, as used in this specification, the shape and geometric conditions and the degree thereof are specified. For example, terms such as “parallel”, “orthogonal”, “identical”, length and angle values, etc. Without being bound by meaning, it should be interpreted including the extent to which similar functions can be expected.

  The conductive mesh 10 is a mesh-like material that defines a large number of open regions 15. As shown in FIGS. 1 and 2, the conductive mesh 10 is made of a conductor 11 that defines an opening region 15, such as silver, aluminum, copper, gold, chromium, molybdenum, nickel, titanium, and alloys thereof. It consists of one or more. The conductor 11 is formed by a line portion 12 extending in a curved shape or a straight shape.

  The conductor 11 has conductivity, and the conductive mesh 10 exhibits some function related to conductivity, and has visible light permeability. As an example of such a conductive mesh 10, an electromagnetic shielding material that is grounded and shields electromagnetic waves, an electrode for a touch panel sensor incorporated in a touch panel device, an antenna having visible light permeability, a collector electrode of a solar cell, dew condensation An exothermic electrode for prevention can be mentioned. As shown in FIG. 2, the conductive mesh 10 is often formed on a transparent base material 35 to form a conductive mesh sheet 30 together with the transparent base material 35.

  Although depending on the specific application of the conductive mesh sheet 30, the transparent substrate 35 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. Examples of such a transparent substrate 35 include resins such as biaxially stretched polyethylene terephthalate (PET), triacetyl cellulose (TAC), polyethylene naphthalate (PEN), polypropylene (PP), cyclic polyolefin, acrylic resin, and polycarbonate resin. A 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.

  In the example shown in FIG. 2, the conductive mesh 10 further has an uneven structure layer 20 formed on the transparent substrate 35. The concavo-convex structure layer 20 has a concavo-convex surface 21 formed by minute protrusions 22. The conductor 11 constituting the conductive mesh 10 extends along the valley bottom 24 that is between the minute protrusions 22 in the uneven surface 21 of the uneven structure layer 20. Accordingly, the conductive mesh sheet 30 shown in FIG. 2 includes the uneven surface 31 corresponding to the unevenness of the uneven surface 21 of the uneven structure layer 20. The unevenness of the uneven surface 31 of the conductive mesh sheet 30 is formed by the minute protrusions 32 formed corresponding to the minute protrusions 22 forming the uneven surface 21 of the uneven structure layer 20. The conductive mesh sheet 30 can exhibit a function caused by the unevenness of the uneven surface 31, for example, an antireflection function described later, a diffusion function, or the like.

  It is preferable that the conductive mesh 10 having visible light permeability is less likely to be visually recognized. On the other hand, it is preferable that the surface resistance of the conductive mesh 10 is sufficiently low so that the function due to the conductivity expected of the conductive mesh 10 can be sufficiently exhibited. In the conductive mesh 10 according to the present invention, the average line width of the conductor 11 is 5 nm or more and 500 nm or less, and the average interval between adjacent opening regions 15 is 50 nm or more and 1000 nm or less. Here, the interval between the opening regions 15 is an arrangement interval between two opening regions 15 adjacent to each other via one line portion 12, and may be a linear distance between the centers of gravity of the opening regions 15, for example. Further, the thickness of the conductor 11 of the conductive mesh 10 is preferably 10 nm or more, and more preferably 100 nm or more, from the viewpoint of ensuring sufficient conductivity.

  The dimensions of the conductive mesh 10 such as the line width of the conductor 11 and the distance between two adjacent opening regions 15 need to be specified by examining the entire region of the conductive mesh 10 and calculating the average value. In fact, in a section having an area expected to reflect the overall tendency of the object to be investigated (such as the line width of the conductor 11 and the interval between two adjacent open regions 15). It can be identified by examining the number considered appropriate in consideration of the degree of variation of the object to be investigated and calculating the average value. The values specified in this way can be handled as the average value of the line width of the conductor 11 and the average value of the distance between two adjacent opening regions 15. For example, in the conductive mesh 10 manufactured by the manufacturing method described below with the value described immediately before as a target, 30 points included in a 30 mm × 30 mm region are measured with an electron microscope to calculate an average. Thus, the line width of the connecting element 20 and the size of the opening region 15 can be specified.

  For a general conductive mesh, for example, a metal film is formed on a transparent substrate by vapor deposition, sputtering, foil transfer, coating, etc., and this metal film is etched using a desired photoresist pattern as a mask. A method, a method of exposing and developing a conductive photosensitive agent (for example, an emulsion in which silver halide grains are diffused) into a desired pattern, or a conductive ink (for example, a conductive ink in which conductive metal particles are dispersed). Can be formed on the transparent substrate by a method such as a method of printing a desired pattern on the transparent substrate. However, the conductive mesh 10 in which the average value of the line width of the conductor 11 and the average value of the distance between two adjacent opening regions 15 are set in the above-described fine range is manufactured by these conventionally known methods. Is difficult.

  As shown in FIG. 2, the conductor 11 provided on the valley bottom 24 of the concavo-convex structure layer 20 first forms the concavo-convex structure layer 20 on the transparent substrate 35. As an example, the concavo-convex structure layer 20 can be produced by shaping an ionizing radiation curable resin as will be described in detail later. As another example, the concavo-convex structure layer 20 can be produced by spreading beads on the resin composition so that the top of the resin composition is exposed from the resin composition, and then curing the resin composition.

  Thereafter, as shown by a dotted line in FIG. 2, a metal thin film 25 is formed on the uneven surface 21 of the uneven structure layer 20. The method for forming the metal thin film 25 is not particularly limited, and examples thereof include vapor phase methods (dry processes) such as sputtering, ion plating, vacuum deposition, and CVD. Thereafter, a part of the metal thin film 25 is removed by etching, polishing, or the like that erodes only the metal thin film 25 without eroding the uneven structure layer 20. At this time, by etching or polishing, the metal thin film 25 can be removed from the portion located on the top 23 of the uneven surface 21 of the uneven structure layer 20. Then, by adjusting the removal amount of the metal thin film 25, the conductor 11 made of metal remaining only in the valley bottom portion 24 of the uneven structure layer 20 can be obtained.

  Instead of forming the metal thin film 25 by film formation and removing part of the metal thin film 25, an appropriate amount of a composition containing metal particles is applied onto the uneven surface 21 of the uneven structure layer 20, and further cured, thereby forming the uneven surface 21. The conductor 11 can also be formed on the bottom 24 of the bottom. Alternatively, by applying a composition containing metal particles onto the concavo-convex surface 21 of the concavo-convex structure layer 20, further curing, and further removing the cured metal-containing composition by etching or polishing as described above, The conductor 11 can also be formed on the valley bottom 24 of the surface 21. Further, the coating amount of the composition containing metal particles on the uneven surface 21 may be adjusted by scraping and removing the composition applied to the uneven surface 21 of the uneven structure layer 20.

  As described above, according to the conductive mesh 10 in which the average line width of the conductor 11 is not less than 5 nm and not more than 500 nm and the average interval between adjacent opening regions 15 is not more than 1000 nm, in general, with human eyes. The conductive mesh 10 cannot be resolved. That is, the conductive mesh 10 described here can be effectively avoided from being visually recognized. Thereby, the permeability | transmittance of the electroconductive mesh 10 and the electroconductive mesh sheet 30 can be improved effectively. Moreover, generation | occurrence | production of the following malfunction resulting from the electroconductive mesh 10 being visually recognized can also be prevented effectively.

  First, since the line width of the conductor 11 forming the conductive mesh 10 is sufficiently narrow, it is possible to prevent the occurrence of glare and shading unevenness. The shading unevenness is considered to be a phenomenon in which the transmittance is locally reduced due to the nonuniformity of the density distribution of the conductor 11 and the nonuniformity of the line width of the conductor 11 in the pattern of the conductive mesh. . On the other hand, the glare is considered to be a phenomenon in which the amount of reflected light locally increases due to the nonuniformity of the density distribution of the conductor 11 in the pattern of the conductive mesh. According to the conductive mesh 10 described here, since the average line width of the conductor 11 is reduced to 500 nm or less, the line portion 12 itself of the conductor 11 is sufficiently invisible, and the shading unevenness is visually recognized. It becomes difficult to be done.

  Further, when a conductive mesh is arranged on a display panel capable of color display, a specific pixel may be covered with a conductor of the conductive mesh. As an example, when white display is performed with typical pixels including a red subpixel, a green subpixel, and a blue subpixel, when the red subpixel is covered with a conductive mesh conductor, it is displayed in light blue instead of white, When the green sub-pixel is covered, it is displayed in magenta instead of white, and when the blue sub-pixel is covered, it is displayed in yellow instead of white. Such a phenomenon is referred to as flickering and reduces color reproducibility. On the other hand, according to the conductive mesh 10 described here, the average line width of the conductor 11 is set to 5 nm or more and 500 nm or less. Therefore, the moiré that has occurred in combination with the members that have been considered to be a problem, for example, the moiré that has occurred in combination with a typical display panel in which sub-pixels are arranged at several tens of μm is effective. Can be made inconspicuous.

  Furthermore, according to the conductive mesh 10 in which the average line width of the conductor 11 is not less than 5 nm and not more than 500 nm and the average interval between the adjacent opening regions 15 is not more than 1000 nm, the conductive mesh 10 is another member. It is possible to effectively make the moire generated when superposed on (components, apparatus) inconspicuous.

  Moire is a phenomenon in which bright and dark streaks become visible, and the regularity (periodicity) of the pattern of the conductive mesh and the regularity of the pattern of other members overlaid on the conductive mesh (for example, a display device) This is caused by interference with the regularity of the pixel arrangement. Therefore, by adjusting the arrangement pitch of the opening regions 15 of the conductive mesh 10 to a pitch that does not cause interference with the regular pattern of other members at an unpleasant pitch, the moire is effectively inconspicuous. be able to. On the other hand, in the conductive mesh 10 described here, in addition to the line width of the conductor 11 being set very thin, the interval between two adjacent open regions 15 is also set very small. Therefore, moire that can occur in combination with members that have been problematic until now, for example, moire that can occur in combination with a typical display panel in which sub-pixels are arranged at several tens of μm, is effectively conspicuous. Can be eliminated. In addition, in the illustrated example, the arrangement of the opening regions 15 of the conductive mesh 10 does not have a periodic pattern. Therefore, the generation of moire can be suppressed extremely effectively.

  Next, application examples of the conductive mesh 10 and the conductive mesh sheet 30 will be specifically described. As described above, the conductive mesh 10 is, for example, an electromagnetic shielding material that is grounded to shield electromagnetic waves, an electrode for a touch panel sensor of a touch panel device, an antenna having visible light permeability, and a solar cell current collector. It can be used as an electrode or a heating electrode for preventing condensation.

  First, as shown in FIG. 3, the conductive mesh 10 is used for television receivers, various measuring devices and instruments, various office devices, various medical devices, computing devices, telephones, electric signboards, various game machines, and the like. It can be incorporated as an electromagnetic wave shielding material in an image display device such as a plasma display (PDP) device, a cathode ray tube display (CRT) device, a liquid crystal display device (LCD), or an electroluminescent display (EL) device used for the display unit.

  In the example shown in FIG. 3, the image display device 40 includes an image forming device (display panel, display unit) 41 that can form an image, and a laminated body 45 that is disposed on the light output side of the image forming device 41. Have. Therefore, the light emitting surface of the stacked body 45 forms the display surface (light emitting surface) 40 a of the image display device 40, and the observer observes the image formed by the image forming device 41 through the stacked body 45. Become. A conductive mesh sheet 30 as an electromagnetic wave shielding sheet is incorporated in the laminated body 45. The conductive mesh 10 of the conductive mesh sheet 30 extends and spreads in a region where an image of the image forming apparatus 41 is formed. While the conductive mesh 10 can effectively shield electromagnetic waves, the conductive mesh 10 is difficult to be visually recognized because the line width is set narrow. For this reason, generation | occurrence | production of malfunctions, such as a moire, shading unevenness, and flicker resulting from the electroconductive mesh 10 being visually recognized can be prevented effectively. In addition, although functional sheets, such as an antireflection sheet and a louver, are appropriately incorporated in the laminated body 45, generation of moire between the conductive mesh 10 and other functional sheets is effectively prevented. become.

  In addition, for electromagnetic shielding applications such as windows for buildings such as houses, schools, hospitals, offices, stores, etc., windows for vehicles such as vehicles, aircraft and ships, windows for various household appliances such as microwave oven windows, etc. It can be used. In this example, the window that supports the conductive mesh 10 as the electromagnetic wave shielding material may form the transparent base material 35 in the conductive mesh sheet 30. In this case, it is possible to effectively prevent the occurrence of moire between the screens and curtains arranged on the windows and the conductive mesh 10, and to receive discomfort due to shading and flickering. This is also effectively prevented.

  Next, an example in which the conductive mesh 10 is applied to the touch panel sensors 51 and 52 of the touch panel device 50 will be described with reference to FIG. FIG. 4 discloses a touch panel device 50 including touch panel sensors 51 and 52. The illustrated touch panel device 50 is configured as a projected capacitively coupled touch panel device, and includes a first touch panel sensor 51 and a second touch panel sensor 52 each having an electrode 55 formed on a transparent substrate 35. ing. The touch panel device 50 is arranged on the image forming apparatus. The first and second touch panel sensors 51 and 52 include an active area Aa1 facing an area where pixels of the image forming apparatus are arranged, and an active area. And an inactive area Aa2 around Aa1. The electrode 55 includes a detection electrode 60 that is located in the active area Aa1 and used for position detection, and an extraction electrode 70 that is connected to the detection electrode 60 and located in the inactive area Aa2.

  Then, as shown in FIG. 4, each detection electrode 60 is connected to a large number of conductive meshes 10 arranged at intervals in the longitudinal direction and connection conductive wires 61 connecting between two adjacent conductive meshes 10. And have. Each detection electrode 60 extends linearly in the active area Aa <b> 1 by the conductive mesh 10 and the connecting conductor 61. The width of the region where each detection electrode 60 is arranged is thicker in the portion where the conductive mesh 10 is provided. Each detection electrode 60 included in one touch panel sensor 51, 52 intersects with a large number of detection electrodes 60 included in the other touch panel sensor 52, 51. As shown in FIG. 4, the conductive mesh 10 of one touch panel sensor 51, 52 is on the detection electrode 60 between the intersections of two adjacent detection electrodes 60 of the other touch panel sensor 52, 51. Has been placed.

  In the touch panel device 50, the conductive mesh 10 of the touch panel sensors 51 and 52 is disposed on a region where the pixels of the image forming apparatus 41 are arranged. The conductive mesh 10 functions as the detection electrode 60 due to its excellent conductivity, and can prevent the occurrence of moire, shading unevenness, and flickering as described above.

  Note that the shape of the electrode 55 shown in FIG. 4 is merely an example, and various modifications are possible. Further, the conductive mesh 10 and the conductive mesh sheet 30 are not limited to the projected capacitive coupling type touch panel device, and can be applied to various types of touch panel devices.

  As another application, the conductive mesh 10 functions as an antenna supported by a window. In addition, the conductive mesh 10 functions as a heat generation electrode for preventing condensation supported by the window. In these examples, the window may form the transparent base material 35 of the conductive mesh sheet 30. In these examples, it is possible to effectively prevent the occurrence of moiré between the screens and curtains arranged on the windows and the conductive mesh 10 and the unevenness of shading and flickering. Receiving pleasure is also effectively prevented.

  Next, the uneven structure layer 20 of the conductive mesh 10 in the illustrated example will be described in further detail. As described above, in the illustrated example, the conductive mesh 10 is formed by the conductor 11 that extends through the valley bottom portion 24 that is between the minute protrusions 22 in the uneven surface 21 of the uneven structure layer 20. Accordingly, the conductive mesh sheet 30 shown in FIG. 2 includes the uneven surface 31 corresponding to the unevenness of the uneven surface 21 of the uneven structure layer 20. The unevenness of the uneven surface 31 of the conductive mesh sheet 30 is formed by the minute protrusions 32 formed corresponding to the minute protrusions 22 forming the uneven surface 21 of the uneven structure layer 20. And the microprotrusion 22 of the uneven | corrugated structure layer 20 is arranged with the space | interval below the shortest wavelength of a visible light band. That is, the uneven structure layer 20 is formed as a moth-eye structure that exhibits an antireflection function, and as a result, the uneven surface 31 of the conductive mesh sheet 30 can exhibit an excellent antireflection function. . Hereinafter, such an uneven structure layer 20 will be described in detail.

The concavo-convex structure layer 20 has a concavo-convex surface 21 formed by minute protrusions 22 arranged at intervals equal to or shorter than the shortest wavelength in the visible light band. Here, “small” of the minute protrusions 22 means that the minute protrusions 22 are minute enough to be arranged at an average interval d _AVG that is equal to or shorter than the shortest wavelength in the visible light band. Further, the shortest wavelength in the visible light band refers to the shortest wavelength in the visible light band in an environment where the conductive mesh 10 is used. Therefore, when only light from a light source limited in an environment where the conductive mesh 10 is used exists, the shortest wavelength of visible light emitted from the light source is the shortest wavelength in the visible light band here. In other cases, 380 nm is adopted as the shortest wavelength in the visible light band here as the shortest wavelength in the general visible light band.

  As described above, the conductor 11 of the conductive mesh 10 extends through the bottom 24 of the uneven surface 21 of the uneven structure layer 20. Therefore, each of the opening regions 15 defined in the conductor 11 of the conductive mesh 10 is provided corresponding to one minute protrusion 22. Therefore, the average of the interval between the two adjacent opening regions 15 described above can be the same as the average of the arrangement interval of the projections of the microprojections 22. For this reason, in the illustrated example, the average interval at which the minute protrusions 32 forming the uneven surface 31 formed on the final conductive mesh 10 are also arranged at an interval equal to or shorter than the shortest wavelength in the visible light band.

  The thickness of the concavo-convex structure layer 20 is not particularly limited, but can be 10 to 300 μm as an example. In this case, the thickness of the concavo-convex structure layer 20 refers to the microprojections 22 forming the concavo-convex surface 21 of the concavo-convex structure layer 20 from the interface on the transparent substrate 35 side of the concavo-convex structure layer 20 as shown in FIG. It means the height along the normal direction nd to the film surface of the conductive mesh 10 up to the top 23.

  The concavo-convex structure layer 20 can be a layer containing a resin, and can be a layer made of a cured product of a resin composition. The resin composition used for forming the concavo-convex structure layer 20 includes at least a resin and, if necessary, other components such as a polymerization initiator.

[Uneven surface]
FIG. 5 shows the uneven surface 21 of the uneven structure layer 20. The concavo-convex surface 21 is formed by minute protrusions 22 arranged at an average interval d _AVG that is equal to or shorter than the shortest wavelength in the visible light band. More preferably, the maximum distance d _MAX between the minute protrusions 22 forming the uneven surface 21 of the uneven structure layer 20 is equal to or shorter than the shortest wavelength in the visible light band. For this reason, the concavo-convex surface 21 of the concavo-convex structure layer 20 has a very excellent antireflection function as a so-called moth-eye structure. For this reason, the uneven surface 31 of the conductive mesh 10 can also exhibit at least some antireflection function.

From the viewpoint of expecting an antireflection function due to the uneven surface 21, the minute protrusions 22 formed on the uneven structure layer 20 have an average interval d _AVG between adjacent minute protrusions 22, more preferably, between adjacent minute protrusions 22. The maximum distance d _MAX is closely arranged so as to be equal to or less than the shortest wavelength Λ _min of the visible light wavelength band that is intended to prevent reflection (d _AVG ≦ Λ _min , d _MAX ≦ Λ _min ). As described above, when light in various wavelength bands is present without particular limitation in the environment where the conductive mesh 10 is used, the shortest wavelength Λ _min of the visible light wavelength band is set to 380 nm. The arrangement interval d of the microprojections 22 can be set to 100 to 300 nm in consideration of the variation of the arrangement interval d. Further, the adjacent minute protrusions 22 related to the distance d are so-called adjacent minute protrusions 22, which are in contact with the bottom 24 of the minute protrusion, which is the base portion on the transparent substrate 35 side. In the conductive mesh sheet 30, as described above, the arrangement interval d of the micro projections 22 corresponds to the arrangement interval of the micro projections 32 of the conductive mesh sheet 30 and also corresponds to the interval of the opening regions 15 of the conductive mesh 10. To come. The adjacent minute protrusions 22 can be said to be two minute protrusions 22 that are partitioned by one line portion 12 of the conductive mesh 10.

The minute protrusions 22 are defined in more detail as follows. The anti-reflection function using the moth-eye structure is intended to prevent reflection by continuously changing the effective refractive index at the interface between the moth-eye structure and the adjacent medium in the thickness direction. It is necessary to satisfy certain conditions. With respect to the spacing of the projections of the moth-eye structure, which is one of these conditions, for example, as disclosed in Japanese Patent Application Laid-Open No. 50-70040, Japanese Patent No. 4632589, etc., the minute projections are regularly arranged at a constant period. If there is, the interval d between adjacent minute protrusions is the protrusion arrangement period P (d = P). As a result, when the longest wavelength in the visible light band is λ _MAX and the shortest wavelength is λ _min , the minimum necessary condition that can provide an antireflection effect at the longest wavelength in the visible light band is Λ _min = λ _MAX . Therefore, P ≦ λ _MAX , and the necessary and sufficient condition that can exhibit the antireflection effect for all wavelengths in the visible light band is Λ _min = λ _min , and therefore P ≦ λ _min .

Note that the wavelengths λ _MAX and λ _min may _vary somewhat depending on the observation conditions, light intensity (luminance), individual differences, and the like, but are typically λ _MAX = 780 nm and λ _min = 380 nm. The A preferable condition that can more reliably exhibit an antireflection effect for all wavelengths in the visible light band is d ≦ 300 nm, and a more preferable condition is d ≦ 200 nm. Note that the lower limit value of the period d is usually d ≧ 50 nm, preferably d ≧ 100 nm, for reasons such as the expression of the antireflection effect and the securing of the isotropic (low angle dependency) of the reflectance. On the other hand, the height H of the protrusion (see FIG. 5) is set to H ≧ 0.2 × λ _MAX = 156 nm (assuming λ _MAX = 780 nm) from the viewpoint of exhibiting a sufficient antireflection effect.

  On the other hand, when the minute protrusions 22 are irregularly arranged, the distance d between the adjacent minute protrusions varies. More specifically, as shown in FIG. 6, when the microprotrusions are not regularly arranged at a constant period in a plan view seen from the normal direction to the front surface or the back surface of the transparent substrate 35, the following is performed: Calculated.

  (1) That is, first, an in-plane arrangement of projections (planar shape of projection arrangement) is detected using an atomic force microscope (AFM) or a scanning electron microscope (SEM). FIG. 6 is an enlarged photograph actually obtained by an atomic force microscope.

  (2) Subsequently, the maximum point of the height of each protrusion (hereinafter simply referred to as the maximum point) is detected from the obtained in-plane arrangement. In addition, as a method for obtaining a maximum point, a method for obtaining a local maximum point by sequentially comparing a planar view shape with an enlarged photograph of a corresponding cross-sectional shape, a method for obtaining a local maximum point by image processing of a planar view enlarged photograph, and an AFM Various methods such as analysis of height data of the microprojections can be applied. FIG. 7 is a diagram showing the detection result of the local maximum point by processing the in-plane distribution data of the height corresponding to the enlarged photograph shown in FIG. 6 (the AFM image grayscale data in FIG. 6 is also roughly corresponding) In this figure, each point indicated by a black dot is a maximum point of each protrusion. In this process, the height data is processed in advance by a low-pass filter having a Gaussian characteristic of 4.5 × 4.5 pixels, thereby preventing erroneous detection of the maximum point due to noise. Further, a maximum point was obtained in units of 1 nm (= 1 pixel) by sequentially scanning a filter for detecting a maximum value of 8 pixels × 8 pixels.

  (3) Next, a Delaunay diagram with the detected maximum point as a generating point is created. Here, Delaunay diagram is obtained by dividing the Voronoi region adjacent to the Voronoi region when the Voronoi division is performed with each local maximum as the generating point, and connecting the adjacent generating points with line segments. It is a net-like figure consisting of a collection of triangles. Each triangle is called a Delaunay triangle, and a side of each triangle (a line segment connecting adjacent generating points) is called a Delaunay line. FIG. 8 is a diagram in which the Delaunay diagram (represented by white line segments) obtained from FIG. 7 is superimposed on the original image of FIG. The Delaunay diagram has a dual relationship with the Voronoi diagram. Voronoi division means that a plane is divided by a net-like figure composed of a set of closed polygons defined by vertical bisectors of line segments (Droney lines) connecting between adjacent generating points. A network figure obtained by Voronoi division is a Voronoi diagram, and each closed region is a Voronoi region.

  (4) Next, the frequency distribution of the line segment length of each Delaunay line, that is, the frequency distribution of the distance between adjacent maximum points (hereinafter referred to as the distance between adjacent protrusions) is obtained. FIG. 9 is a histogram of the frequency distribution created from the Delaunay diagram of FIG. In addition, when the top part 23 of the projection 22 has a recess such as a groove shape, or when the top part 23 is divided into a plurality of peaks, there is a recess at the top part of such a projection from the obtained frequency distribution. The data resulting from the fine structure and the fine structure in which the top part is divided into a plurality of peaks are removed, and only the data of the projection body itself is selected to create a frequency distribution.

  Specifically, a fine structure in which a concave portion exists in the top portion 23 of the protrusion 22 and a fine structure related to the multi-modal fine protrusion 22 in which the top portion 23 is divided into a plurality of peaks are provided with such a fine structure. From the numerical range in the case of the unimodal microprotrusions 22 that are not, the distance between adjacent local maximum points is clearly greatly different. Thus, by removing the corresponding data using this feature, only the data of the projection body itself is selected and the frequency distribution is detected. More specifically, for example, about 5 to 20 adjacent single-peaked microprojections are selected from an enlarged photograph of a microprojection (group) in plan view as shown in FIG. 6, and the distance between adjacent maximum points is selected. The value of is sampled and the value clearly deviates from the numerical range obtained by sampling (usually data whose value is ½ or less of the average distance between adjacent maximum points obtained by sampling) To detect the frequency distribution. In the example of FIG. 9, data (the leftmost mound indicated by the arrow A) in which the distance between adjacent maximum points is 56 nm or less is excluded. FIG. 9 shows a frequency distribution before such exclusion processing is performed. Incidentally, such exclusion processing may be executed by setting the above-described maximum inspection filter.

(5) The average value (average interval) _dAVG and the standard deviation σ are determined from the frequency distribution of the distance d between adjacent protrusions determined in this way. Here, when the frequency distribution obtained in this manner is regarded as a normal distribution and the average value d _AVG and the standard deviation σ are obtained, the average value d _AVG = 158 nm and the standard deviation σ = 38 nm are obtained in the example of FIG. Thereby, the maximum value d _{MAX of the} distance between adjacent protrusions is set to d _MAX = d _AVG + 2σ, and in this example, d _MAX = 234 nm.

The same method is applied to define the height of the protrusion. In this case, a relative height difference of each local maximum point position from a specific reference position is acquired from the local maximum point obtained by the above (2), and is histogrammed. FIG. 10 is a diagram showing a histogram of the frequency distribution of the protrusion height H with the protrusion root position obtained in this way as a reference (height 0). The average value _HAVG of the protrusion height and the standard deviation σ are obtained from the frequency distribution based on the histogram. Here in the example of FIG. 10, the mean value _H AVG = 178 nm, the standard deviation sigma = 30 nm. Thus in this example, the height of the projections is an average value _H AVG = 178 nm. In the histogram of the projection height H shown in FIG. 10, in the case of a multi-peak microprojection, the plurality of data are mixed for one projection by having a plurality of apexes. Therefore, in this case, the frequency distribution is obtained by adopting, as the projection height of the microprojection, the top portion having the highest height from among the plurality of apexes belonging to the same microprojection.

  The reference position for measuring the height of the protrusion described above is based on the valley bottom 24 between the adjacent minute protrusions as a reference for the height 0. However, when the height of the valley bottom 24 itself varies depending on the location (for example, as shown in FIG. 14, the height of the valley bottom 24 has undulation at a period larger than the distance between adjacent protrusions of the minute protrusions, etc. (1) First, the average value of the height of each valley bottom 24 measured from the front surface or the back surface of the transparent substrate 35 is calculated within an area sufficient for the average value to converge. (2) Next, a plane having the average height and parallel to the front or back surface of the transparent substrate 35 is considered as a reference plane. (3) Then, the height of each microprotrusion from the reference surface is calculated by setting the reference surface to a height of 0 again.

When the height of the valley bottom 24 between the adjacent minute protrusions 22 differs depending on the location, for example, as shown in FIG. 14, the envelope surface connecting the valley bottoms between the minute protrusions has the longest wavelength λ _{MAX in the} visible light band. In some cases, the above period D (that is, D> λ _MAX ) undulates. The periodic waviness is constant in only one direction (for example, the X direction) on a plane (XY plane in FIG. 14) parallel to the front and back surfaces of the transparent substrate 35 and in a direction orthogonal to the direction (for example, the Y direction). Alternatively, the two directions (X direction and Y direction) in a plane parallel to the front and back surfaces of the transparent substrate 35 (XY plane in FIG. 14) may have undulations. The concave / convex surface 26 that undulates with a period D satisfying D> λ _MAX is superimposed on a microprojection group composed of a large number of microprojections, whereby the reflected light remaining without being completely antireflected by the microprojections group is scattered, It is further difficult to visually recognize the shiodome reflected light, in particular, the specular reflected light, so that the transmission visibility of the conductive mesh 10 can be further improved.

When the period D of the concavo-convex surface 26 is not constant over the entire surface and has a distribution, the frequency distribution of the distance between the convexes is obtained for the concavo-convex surface, and the average value is D _AVG and the standard deviation is Σ. When
D _min = D _AVG -2Σ
Designed as an alternative to period D with a minimum inter-protrusion distance defined as That is, conditions that can sufficiently exhibit the scattering effect of the reflected light of the microprojections are as follows:
D _min > λ _MAX
It is. Usually, D or D _min can be 200 μm or less.

In the case where the protrusions are irregularly arranged, the average value d _{AVG of the} distances between adjacent protrusions and the average value (average height) _HAVG of the heights of the protrusions thus obtained are regularly arranged. It has been found that satisfying the above-mentioned conditions in some cases is somewhat effective in terms of imparting an effective antireflection function to the concavo-convex structure layer 20. Specifically, the condition of the distance between the microprotrusions that exhibits the antireflection effect is d _AVG ≦ Λ _min . Since the minimum necessary condition that can exhibit the antireflection effect at the longest wavelength in the visible light band is Λ _min = λ _MAX , d _AVG ≦ λ _MAX is satisfied, and antireflection is performed for all wavelengths in the visible light band. The necessary and sufficient condition that can produce the effect is Λ _min = λ _min , and therefore d _AVG ≦ λ _min . A preferable condition that can effectively exhibit the antireflection effect for all wavelengths in the visible light band is d _AVG ≦ 300 nm, and a more preferable condition is d _AVG ≦ 200 nm. Further, for reasons such as ensuring the manifestation of the antireflection effect, d _AVG ≧ 50 nm is usually satisfied, and d _AVG ≧ 100 nm is preferable. Such a condition is a condition relating to the interval between the opening regions 15 for making the conductive mesh 10 invisible, that is, the average of the interval between the two adjacent opening regions 15 or the minute protrusions 22 is 50 nm or more and 1000 nm or less. Satisfy the conditions.

Further, the height of the protrusion is set to H _AVG ≧ 0.2 × λ _MAX = 156 nm (assuming λ _MAX = 780 nm) in order to exhibit a sufficient antireflection effect. From the viewpoint of enabling an excellent antireflection function to be exhibited even in the conductive mesh sheet 30 on which the conductive mesh 10 is formed, the protrusion height of the fine protrusion 32 of the conductive mesh sheet 30 is 156 nm or more. In consideration of the thickness of the conductor 11 of the conductive mesh 10, it is preferable to determine the projection height of the microprojections 22 of the concavo-convex structure layer 20.

6 to 10, d _MAX = 234 nm ≦ λ _MAX = 780 nm, which satisfies the condition of d _MAX ≦ λ _MAX , and the uneven structure layer 20 and the conductive mesh sheet 30 have sufficient antireflection effect. It can be seen that Further, since the shortest wavelength λ _{min in the} visible light band is 380 nm, the concavo-convex structure layer 20 and the conductive mesh sheet 30 also satisfy the sufficient condition d _MAX ≦ λ _{min for} exhibiting the antireflection effect in the entire visible light wavelength band. I understand that. Further, since the average protrusion height H _AVG = 178 nm, the average protrusion height H _AVG ≧ 0.2 × λ _MAX = 156 nm (assuming that the longest wavelength λ _MAX = 780 nm in the visible light wavelength band), the conductive mesh 10 is It can be seen that the conditions relating to the height of the protrusions to achieve a sufficient antireflection effect are also satisfied. Note since the standard deviation sigma = 30 _nm, since the relationship between the _{H AVG -σ = 148nm <0.2 ×} λ MAX = 156nm is satisfied, statistically, more than 50% of the total fine protrusions 22, 84 % Or less satisfies the condition of the height of the protrusion (178 nm or more).

  Next, a method for manufacturing the uneven structure layer 20 will be described. FIG. 11 is a diagram showing a method for manufacturing the concavo-convex structure layer 20. In the illustrated manufacturing method, in the resin supplying step, an uncured and liquid ultraviolet curable resin that forms the concavo-convex structure layer 20 on the transparent base material 35 in the form of a strip film is applied by the die 92. In addition, about application | coating of ultraviolet curable resin, not only the case by the die | dye 92 but various methods are applicable. Subsequently, the transparent base 35 is pressed against the peripheral side surface of a roll plate (die) 93 that is a mold for forming the concavo-convex structure layer by the pressing roller 94, and thereby the liquid is uncured on the transparent base 35. The acrylate-based ultraviolet curable resin is closely attached, and the ultraviolet curable resin is sufficiently filled in the concave portions having fine irregularities formed on the peripheral side surface of the roll plate 93. In this state, the ultraviolet curable resin is cured by irradiation of ultraviolet rays, and thereby the concavo-convex structure layer 20 having the fine protrusions 22 on the surface of the transparent substrate 35 is produced. Next, the transparent substrate 35 is peeled from the roll plate 93 using the peeling roller 95 integrally with the concavo-convex structure layer 20 made of a cured ultraviolet curable resin. Thereafter, as described above, the conductive mesh 10 is formed using the unevenness of the uneven surface 21 of the uneven structure layer 20. Thereby, the electroconductive mesh 10 is obtained.

  FIG. 12 is a perspective view showing the configuration of the roll plate 93. The roll plate 93 has a fine concavo-convex shape for shaping the concavo-convex surface 21 of the concavo-convex structure layer 20 on the peripheral side surface of the base material, which is a cylindrical metal material, by repeating anodizing treatment and etching treatment. The For this reason, a columnar or cylindrical member in which a high-purity aluminum layer is provided at least on the peripheral side surface is used as the base material. As an example, a hollow stainless steel pipe is applied to the base material, and a high-purity aluminum layer is provided directly or via various intermediate layers. Instead of the stainless steel pipe, a pipe material such as copper or aluminum may be applied. In the roll plate 93, fine holes are densely formed on the peripheral side surface of the base material by repeating the anodizing treatment and the etching treatment, and the fine holes are dug, and the diameter of the roll plate 93 increases as it approaches the opening. The concavo-convex shape is produced by gradually increasing the diameter of the fine holes. As a result, the roll plate 93 is densely formed with fine holes whose diameter gradually decreases in the depth direction, and the diameter of the concavo-convex structure layer 20 gradually increases toward the top 23 corresponding to the fine holes. An uneven surface 21 made up of a large number of small protrusions 22 is produced. At this time, a roll plate 93 capable of shaping the uneven surface 21 described above by appropriately adjusting various conditions such as purity (amount of impurities), crystal grain size, anodizing treatment and / or etching treatment of the aluminum layer. Can be produced.

  FIG. 13 is a diagram showing a method for manufacturing the roll plate 93. In this manufacturing method, first, the peripheral side surface of the base material is made into a super-mirror surface by an electrolytic composite polishing method that combines an electrolytic elution action and a rubbing action by abrasive grains (electropolishing). Subsequently, aluminum is sputtered on the peripheral side surface of the base material to produce a high-purity aluminum layer. Next, the base material is processed by alternately repeating the anodic oxidation steps A1,..., AN, and the etching steps E1,.

  In this manufacturing method, in the anodic oxidation steps A1,..., AN, a fine hole is formed on the peripheral side surface of the base material by the anodic oxidation method, and the produced fine hole is further dug. Here, in the anodic oxidation step, various methods applied to the anodic oxidation of aluminum can be widely applied, for example, when a carbon rod, a stainless steel plate, or the like is used for the negative electrode. Further, as the solution, various neutral and acid solutions can be used. More specifically, for example, a sulfuric acid aqueous solution, an oxalic acid aqueous solution, a phosphoric acid aqueous solution and the like can be used. In this manufacturing process A1,..., AN, a fine hole can be formed in a shape corresponding to the shape of the microprojection 22 to be produced by managing the liquid temperature, the applied voltage, the time for anodization, and the like. it can.

  In the subsequent etching process E1,..., EN, the mold is immersed in an etching solution, the hole diameter of the fine hole produced and dug in the anodizing process A1,. These fine holes are shaped so that the hole diameter becomes smaller and smoother. As the etching solution, various etching solutions that are applied to this type of treatment can be widely applied. More specifically, for example, a sulfuric acid aqueous solution, an oxalic acid aqueous solution, a phosphoric acid aqueous solution, or the like can be used. As a result, in this manufacturing process, the anodizing process and the etching process are alternately performed a plurality of times, so that fine holes for forming are formed on the peripheral side surface of the base material.

  Note that the roll plate 93 for producing the concavo-convex structure layer 20 described with reference to FIG. 14, that is, the concavo-convex structure layer 20 in which the height of the valley between the adjacent microprojections 22 varies depending on the location, Can be manufactured in this way. In other words, in the manufacturing process of the roll plate 93, a concavo-convex shape corresponding to the concavo-convex shape of the concavo-convex surface 26 is formed on the surface of a cylindrical (or columnar) base material by sandblasting or mat (matte) plating. Next, an appropriate intermediate layer is formed directly or if necessary on the uneven surface, and then an aluminum layer is laminated. Thereafter, an aluminum layer having a surface shape corresponding to the uneven surface is subjected to anodizing treatment and etching treatment in the same manner as described above to form the uneven surface 21 including the fine protrusions 22. 93 is obtained.

  By using the roll plate 93 produced in this way, the concavo-convex structure layer 20 can be produced. As described above, by using the fine uneven surface 21 of the uneven structure layer 20, it is possible to easily produce the conductive mesh 10 in which the conductor 11 has a narrow line width and a narrow interval between the opening regions 15. It becomes. The conductive mesh 10 thus produced can be effectively avoided from being visually recognized due to the narrow line width of the conductor 11 and the narrow interval between the opening regions 15. Further, the conductive mesh sheet 30 has an uneven surface 31 corresponding to the uneven surface 21 of the uneven structure layer 20, and the uneven surface 31 exhibits an excellent antireflection function. That is, the conductive mesh sheet 30 has an antireflection function in addition to a function caused by the conductivity of the conductive mesh 10, for example, an electromagnetic wave shielding function.

  The inventor actually uses the concavo-convex structure layer 20 shown in FIGS. 6 to 8 to actually use the conductive mesh sheet 30 composed of the transparent substrate 35, the concavo-convex structure layer 20, and the conductive mesh 10. It was prepared. Then, when the produced conductive mesh 30 is placed on a liquid crystal display panel having a pixel pitch of 84 μm (sub-pixel pitch is 28 μm) and observed, the conductor of the conductive mesh 10 is used with normal attention. 11 was not visually recognized. Also, defects such as moire, shading unevenness, and flickering were not recognized even after careful observation. The confirmation of the conductive mesh 10, moire, shading unevenness, and flickering was performed in a state where the liquid crystal display panel displayed white on the entire surface, that is, under conditions where the target defect was more easily visible.

DESCRIPTION OF SYMBOLS 10 Conductive mesh 11 Conductor 12 Line part 15 Opening area 20 Uneven structure 20
DESCRIPTION OF SYMBOLS 21 Uneven surface 22 Microprotrusion 23 Top 24 Valley bottom 25 Metal thin film 30 Conductive mesh sheet 31 Uneven surface 32 Microprotrusion 35 Transparent base material 40 Image display device 40a Display surface 41 Image forming device, display panel, display unit 45 Laminate 50 Touch panel device 51 First touch panel sensor 52 Second touch panel sensor 55 Electrode 60 Detection electrode 61 Connection lead 70 Extraction electrode

Claims (3)

An uneven structure layer having an uneven surface formed by minute protrusions;
A conductive mesh formed by a conductor extending along the bottom of the concave-convex surface of the concave-convex structure layer between the microprotrusions, and
The average line width of the conductor is 5 nm or more and 500 nm or less,
A conductive mesh sheet having an average interval between adjacent minute protrusions of 1000 nm or less. A touch panel device comprising the conductive mesh sheet according to claim 1 . An image display device comprising the conductive mesh sheet according to claim 1 .