JP2015153320A - Front protective plate for display device, and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a less costly front protective plate for display device with a light shielding layer expressing a color design of white color hard to be yellowed, and to provide a display device having the same.SOLUTION: A front protective plate for display device 10 has a white color resin layer 2w as a light shielding layer 2 in a portion of an opaque region A2 of a transparent substrate 1. Further, yellowing prevention layer 3, which also serves as an invisible layer with a less visible pattern of a transparent electrode 4, is provided over the display area A1 of the light-transmitting substrate 1 so as to cover the white color resin layer. If a touch panel integrated type front protective plate for display device is provided in addition to a transparent electrode for the touch panel, the cost is suppressed and yellowing prevention and non-visualization can both be achieved since invisualization of the transparent electrode is simultaneously achieved in the yellowing prevention layer. The display device is configured using this front protective plate for display device.

Description

  The present invention relates to a front protective plate for a display device and a display device including the same.

  In recent years, touch panels used in combination with display panels are rapidly spreading in various display devices such as smartphones and tablet PCs (personal computers).

  FIG. 14 is a diagram schematically illustrating an example of a conventional display device 200 including the touch panel 20. 14A is an exploded plan view, and the cross-sectional view of FIG. 14B is the exploded plan view of FIG. 14A, in which the conventional front protective plate 40 for a display device is cut along line CC. It is sectional drawing of only the front protection plate 40 for display devices at the time. The touch panel 20 is disposed on the front side (the front side in the drawing) that is the light output side of the display light from the display panel 30 with respect to the display panel 30. Further, in order to protect the touch panel 20, a front protective plate for display device 40 is disposed on the front side of the touch panel 20, which is the side from which the display light from the display panel 30 passes through the touch panel 20 and emits light (Patent Literature). 1, Patent Document 2, Patent Document 3).

  As shown in FIG. 14, the conventional front protective plate 40 for a display device usually has an outer peripheral portion of the display area A1 as an opaque area A2, and a light shielding layer 42 is translucent in the opaque area A2. It is formed on the substrate 41. The light shielding layer 42 is usually formed as a colored resin layer containing a color pigment in a resin binder, and the color of the light shielding layer 42 is usually black from the viewpoint of light shielding properties. The opaque region A2 prevents the touch panel 20 disposed on the back side of the front protective plate 40 for display device from seeing the wiring 6 and connectors on the outer peripheral portion so as not to impair the appearance. In the opaque region A2, visible information 8 such as a product logo, an infrared transmission window, and a notification window indicating the state of the device are also provided as appropriate. The opaque region A2 is provided with an additional front protective plate 40 for the display device. It is also a decoration part.

Each member of the front protective plate 40 for the display device, the touch panel 20 and the display panel 30 may be closely stacked by being filled with a resin layer without providing a gap between these members. By doing so, it is possible to reduce display light loss due to interface reflection and external light reflection to make the display easier to see.
Further, in order to meet the demands for thinning, lightening, and reduction in the number of parts, various integrations such as integration of the front protective plate 40 for the display device and the touch panel 20 or integration of the touch panel 20 and the display panel 30 are possible. A form has been proposed and put into practical use (Patent Document 1, Patent Document 2).

JP 2009-193587 A Utility Model Registration No. 3153971 JP 2008-266473 A (FIG. 2)

By the way, the light shielding layer 42 in the opaque region A2 is usually black from the viewpoint of light shielding properties, but recently, a white design such as pure white or ivory color is desired by changing the taste. Sometimes.
Therefore, if the light shielding layer 42 is formed of a white resin layer containing a white pigment in a resin binder instead of a black pigment such as carbon black so that a white color design can be expressed, the white color system is temporarily formed. Color design can be expressed. However, with this configuration, it has been found that the color of the light shielding layer 42 turns yellow and the design properties are lowered. The yellowing is considered to be caused by the deterioration of the resin component used in the light shielding layer 42 due to light deterioration over time. When the color of the light shielding layer 42 is black, the resin component is yellowed. Seems to have been inconspicuous. Yellowing was particularly noticeable when the white resin layer 2w was formed as a cured layer of a photosensitive resin by a photolithography method in that the pattern accuracy was excellent.
For this reason, the light-shielding layer 42 in which a white color design is expressed using a white resin layer has been desired to have light resistance that is difficult to yellow.

  In addition, when a transparent electrode for a touch panel is provided in the display area A1, the pattern may appear faint and may interfere with viewing the display screen.

Accordingly, a first problem of the present invention is to provide a front protective plate for a display device in which a light shielding layer expressing a white color design is less likely to yellow, and a display device including the same.
The second problem of the present invention is to provide a front protective plate for a display device in which a transparent electrode pattern is difficult to see, and a display device including the same.
In addition, a third problem of the present invention is that a front protection plate for a display device having a structure capable of realizing both the first problem and the second problem while suppressing an increase in cost, and a display device including the same. Is to provide.

In the present invention, the front protective plate for a display device and the display device are configured as follows.
(1) A front protective plate for a display device having a central display area and an opaque area that is provided on an outer periphery of the display area and shields visible light,
A translucent substrate;
A light shielding layer provided in the opaque region on any one of the first surface of the translucent substrate and the second surface opposite to the first surface;
The light shielding layer has a white resin layer containing at least a white pigment in a resin binder,
Furthermore, on one surface of the translucent substrate, it has a yellowing prevention layer provided so as to cover the white resin layer,
The yellowing prevention layer is formed to extend to the display region, and also serves as an invisible layer that makes it difficult to see the pattern of the transparent electrode that can be formed in the display region.
Front protective plate for display devices.
(2) On one surface of the translucent substrate, the transparent electrode extends from the display region to the surface of the opaque layer in the opaque region,
The yellowing prevention layer is formed to extend from the opaque region having the white resin layer to the display region including the transparent electrode forming portion and the non-forming portion.
(1) The front protective plate for a display device.
(3) a display panel;
The front protective plate for a display device according to (1) or (2), which is disposed on the front side from which display light from the display panel is emitted;
Comprising at least
Display device.

  According to the front protective plate for a display device and the display device of the present invention, the white color design expressed by the light shielding layer is hardly yellowed, and when the transparent electrode is provided, the pattern of the transparent electrode is difficult to see. Moreover, the prevention of yellowing and the invisibility of the transparent electrode can be realized while suppressing the increase in cost.

The top view (a) explaining one Embodiment (yellowing prevention layer which coat | covers a light shielding layer also including a backing layer) by the front protection plate for display apparatuses by this invention, and sectional drawing in CC line in a top view (B). It is sectional drawing explaining the invisible function of the yellowing prevention layer which serves as an invisible layer, and there is no invisible layer (a), an invisible layer is between a translucent substrate and a transparent electrode (b), and a transparent electrode is The figure which shows the structural example of (c) between a translucent board | substrate and an invisible layer. It is sectional drawing explaining the invisible function of the yellowing prevention layer which serves as an invisible layer, and is a figure which shows the case where the refractive index of an invisible layer is the same as the refractive index of a transparent electrode. It is sectional drawing explaining the invisible function of the yellowing prevention layer which serves as an invisible layer, and is a figure which shows the case where the refractive index of an invisible layer is larger than the refractive index of a transparent electrode. The top view seen from the back side explaining another embodiment (touch panel function integration) of the front surface protection plate for display apparatuses by this invention. The top view and sectional drawing (b) explaining an example of the cross | intersection part of the transparent electrode of FIG. Sectional drawing explaining embodiment of FIG. Sectional drawing explaining the deformation | transformation form (A yellowing prevention layer is between a white-type resin layer and a backing layer) of the front surface protection plate for display apparatuses by this invention. Sectional drawing explaining the deformation | transformation form (a yellowing prevention layer is the back side of a transparent electrode) of the front surface protection plate for display apparatuses by this invention. Sectional drawing explaining the deformation | transformation form (The yellowing prevention layer is the front and back both sides of a transparent electrode) of the front surface protection plate for display apparatuses by this invention. Sectional drawing which illustrates typically one Embodiment (touch-panel transparent electrode integration) of the display apparatus by this invention. Sectional drawing which illustrates typically another embodiment (touch panel transparent electrode partial integration) of the display apparatus by this invention. Sectional drawing which illustrates typically another embodiment (touch panel separate body) of the display apparatus by this invention. An exploded plan view (a) showing an example of a conventional front protective plate for a display device and a display device, and a cross-sectional view (b) of the front protective plate for a display device along line CC in the exploded plan view.

    Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings are conceptual diagrams, and the scale relations, aspect ratios, and the like of components may be exaggerated as appropriate for convenience of explanation.

[A] Definition of terms:
Hereinafter, definitions of main terms used in the present invention will be described here.

The “front side” is the side from which the display light from the display panel is emitted when the front protective plate for display device is used in combination with the display panel in the front protective plate for display device or other components. This means the side that observes the panel display.
The “back side” means a side opposite to the “front side”, and means a side where display light of the display panel enters in the front protective plate for display device or other components.
The “outside” means a side far from the display area in the component formed in the opaque area, in other words, a side near the outer periphery of the front protective plate for the display device.
The “inner side” means a side opposite to the “outer side” in the component formed in the opaque area, in other words, the side close to the display area.
Any one of the “first surface” and the “second surface” is the “front side”, and which surface is the “front side” is arbitrary.
Originally, “one side” and “the other side” which is the opposite side are either “front side” and which side is the “front side”. In the present invention, the surface of the translucent substrate that always has the light shielding layer is referred to as “one surface”, and this one surface is used as the back surface. Further, in the present invention, the surface that becomes the “front side” will be referred to as the “first surface”, and the surface that becomes the “back side” will be described as the “second surface”. Therefore, the “one surface” or “back side” surface having the light shielding layer is the “second surface”, and the “other surface” or “front side” surface is the “first surface”.
The meaning of “white color” will be described later in the light shielding layer column.

[B] Front protective plate for display device:
Hereinafter, a front protective plate for a display device according to the present invention will be described.

<< First embodiment: Yellowing prevention layer covering a light shielding layer including a backing layer >>
A first embodiment of a front protective plate for a display device according to the present invention will be described with reference to FIG. FIG. 1A is a plan view, and FIG. 1B is a cross-sectional view.

  As shown in the plan view of FIG. 1A, the front protective plate 10 for a display device according to the embodiment shown in FIG. 1 is provided in the central display area A1 and the outer peripheral portion of the display area A1. And an opaque region A2. The cross-sectional view of FIG. 1B is a cross-sectional view taken along line CC in the plan view of FIG. As shown in the cross-sectional view of FIG. 1B, the front protective plate 10 for a display device according to this embodiment includes a translucent substrate 1, a first surface S1 of the translucent substrate 1, and a first surface S1. The light shielding layer 2 provided in the opaque region A2 is provided on the second surface S2 of the two surfaces of the second surface S2 opposite to the first surface S2.

  In the front protective plate 10 for a display device in the present embodiment, the light shielding layer 2 is provided on the second surface S2 of the translucent substrate 1, and this second surface S2 is the back side, in other words, the second surface S2 is Assuming that the first surface S1 is used toward the viewer V side of the display of the display panel 30 toward the touch panel 20 or the display panel 30 side indicated by the phantom line of the two-point difference line in FIG. It is a form.

  In this embodiment, the light shielding layer 2 is composed of a white resin layer 2w and a backing layer 2b in this order from the translucent substrate 1 side.

  In the present embodiment, the white resin layer 2w includes a white pigment in a resin binder and exhibits a white color. In the present embodiment, the white resin layer 2w does not include a color pigment for coloring a chromatic color other than a white pigment and a black pigment for reducing brightness. In the present embodiment, the white resin layer 2w is formed as a layer that increases the reflectance to increase the brightness and bears white as the basic color of the white color design.

  The backing layer 2b is formed on the surface of the yellowing prevention layer 3 so as to overlap the white resin layer 2w. The backing layer 2b is formed of a dark resin layer that contains a color pigment in a resin binder made of a cured photosensitive resin and exhibits a dark color and has a light shielding property greater than that of the white resin layer 2w. In the present embodiment, the dark resin layer serving as the backing layer 2b includes a black pigment in a resin binder and exhibits a black color. The dark color resin layer is formed by a photolithography method using a dark color photosensitive resin composition containing a black pigment in a resin binder.

In this embodiment, the yellowing prevention layer 3 serves as a layer that also serves as an invisible layer, and includes a light shielding layer 2 composed of a white resin layer 2w and a backing layer 2b, and both outer side surfaces and inner side surfaces. It is formed so as to be covered. In addition, the yellowing prevention layer 3 is formed of the same material at the same time as the invisible layer in the display area A1, and as the yellowing prevention layer 3 in the opaque area A2. It is formed as a continuous layer over the opaque region A2.
The invisible layer is a layer that makes it difficult to see the pattern when the transparent electrode 4 is patterned in the display area A1. In FIG. 1B, the transparent electrode 4 is not included in the constituent elements in the present embodiment, and thus is indicated by an phantom line of a two-dot chain line.
Since the yellowing prevention layer 3 has a function as an invisible layer with respect to the transparent electrode 4, it shows electrical insulation and shows transparency. In the present embodiment, the yellowing prevention layer 3 is formed by a vapor deposition method as an inorganic layer containing niobium pentoxide (Nb ₂ O ₅ ). As a result, the yellowing prevention layer 3 is set as an invisible layer, and the refractive index n3 is set larger than the refractive index n4 of the transparent electrode 4.

  Thus, the yellowing prevention layer 3 is formed as a layer that also serves as an invisible layer, so that it is not necessary to provide each layer in a separate process, and the yellowing prevention and invisibility are increased in cost. It can be realized together.

  As described above, in the front protective plate 10 for the display device of the present embodiment, the white color design expressed by the light shielding layer 2 including the white resin layer 2w is not easily yellowed, and the transparent electrode 4 is In the case where it is provided, the pattern of the transparent electrode 4 is difficult to see, and further, it is possible to achieve both the prevention of yellowing and the invisibility by suppressing the increase in cost.

  Hereinafter, each component will be further described in detail.

[Display area A1 and opaque area A2]
As illustrated in the plan view of FIG. 1A, the display device front protective plate 10 has a display area A1 at the center, and an opaque area A2 that shields visible light from the outer periphery of the display area A1. Have When the display area A1 is applied to the display panel 30 indicated by the phantom line of the two-dot chain line in the cross-sectional view of FIG. 1B, the display panel 30 displays through the front protection plate 10 for the display device. It is an area that can display the contents to be displayed. The opaque region A2 is a touch panel when the wiring, connector, etc., which the display panel 30 has on the outer peripheral portion is hidden, or when applied to the touch panel 20 indicated by a two-dot chain line imaginary line in the cross-sectional view of FIG. Reference numeral 20 denotes an area for hiding opaque wiring, connectors, and the like that are provided on the outer periphery thereof. Further, the opaque area A2 is an area that also serves as a decoration portion by visible information 8 such as a color expressed by the logo, a logo or a mark provided as appropriate.

[Translucent substrate 1]
The translucent substrate 1 is not particularly limited as long as it is transparent to at least visible light and has a mechanical strength capable of protecting the surface of the display panel to which the front protective plate 10 for a display device is applied. Typically, a glass plate such as soda-lime glass, borosilicate glass, quartz glass, or aluminosilicate glass can be used. In particular, as a glass plate, chemically strengthened glass is preferable in that it has excellent mechanical strength compared to float glass and can be made thinner by that amount.
Resin can also be used for the translucent substrate 1. For example, an acrylic resin, a polycarbonate resin, a cycloolefin resin, a polyester resin, or the like can be used as the resin. By using a resin for the light-transmitting substrate 1, the weight can be reduced and flexibility can be provided.
For the light-transmitting substrate 1, a laminate of glass and resin can also be used. By using a laminated body of glass and resin for the light-transmitting substrate 1, both glass characteristics and resin characteristics can be provided.

(Refractive index)
The refractive index n1 of the translucent substrate 1 is usually about 1.45 to 1.65 when glass is used, and is usually about 1.45 to 1.60 when resin is used. Specific examples of the refractive index n1 are 1.52 for glass, 1.49 for acrylic resin, 1.59 for polycarbonate resin, and 1.58 for polyester resin.

[Light shielding layer 2]
The light shielding layer 2 in the embodiment illustrated in FIG. 1 is formed in a portion of the opaque region A2 of the second surface S2 on the back side that is the touch panel 20 and the display panel 30 side of the translucent substrate 1. The light shielding layer 2 is provided in the entire area in the opaque area A2. In other words, the opaque region A2 is formed as an opaque region by the light shielding layer 2.
In the present embodiment, the light shielding layer 2 is formed in the opaque region A2 of the surface of the second surface S2 as one of the first surface S1 and the second surface S2 of the translucent substrate 1.
The light-shielding layer 2 is a wiring or control circuit that the touch panel 20 has on its outer peripheral portion with respect to its central position detection region, or a wiring or control that the display panel 30 has on its outer peripheral portion with respect to its central display region. The display device using the touch panel 20 or the display panel 30 has a function of hiding the circuit and the like so that the appearance is not impaired.

  The light-shielding property of the light-shielding layer 2 depends on required specifications and expression color, but in terms of transmittance, it is at most 1% or less (optical density OD2.0 or more), preferably transmittance is 0.1% or less (optical) Density OD3.0 or more), and more preferably 0.01% or less (optical density OD4.0 or more) in terms of transmittance.

The light shielding layer 2 has a function as a decorative layer for improving the appearance design of the front protective plate 10 for a display device as well as a light shielding property for hiding unnecessary components.
In the present invention, the light shielding layer 2 represents a white color design, for example, a white color with a chromatic color, or an achromatic pure white or a very light grayish white color. To do.
In the present embodiment, the light shielding layer 2 expresses white as a white color design.

  Hereinafter, the white color, the white resin layer 2w, and the backing layer 2b will be described.

[What is a white color?]
In the present invention, the light shielding layer 2 has a white color in addition to pure white (pure white), yellowish white which is yellowish white, ivory, beige and reddish white which is reddish white (light Pink), yellowish white as yellowish white, bluish white as blue white, green white as green white, purple white as purple white, brown white as brown white, blackish white Also included are chromatic and whitish colors, and achromatic and whitish colors, such as white gray (light gray), silvery white that is silvery white, and gold white that is golden white.
If these white colors are numerically shown, they can be defined using various color systems. In particular, if shown by the Munsell color system (JIS Z 8721), which is one of the conventional color systems, in the present invention, the white color is a lightness of 8.0 or more in the Munsell color system. Further, it can be defined as a color having a saturation of 2.0 or less. The hue of the white color may be any color.

In the Munsell color system, all colors are represented by three attributes of brightness, saturation, and hue. In the Munsell color system, this brightness is 10 for the brightest ideal white and 0 for the darkest ideal black. In the present invention, the white color can be set to 8, even if the brightness is small, and can be set to 8.0 or more. In the Munsell color system, the saturation is 0 for an achromatic color, the value increases as the color becomes darker, and the maximum value varies with lightness and hue but is 14 at the maximum. Since the white color is a whitish color, the saturation can be 2 or less and 2.0 or less.
The three attributes of the Munsell color system can be measured with a commercially available spectrophotometer, spectrophotometer, or the like.
Among the white colors, particularly whitish colors are expressed by the Munsell color system, the color is 9.0 or more in brightness and 1.0 or less in saturation, and the whitish color is lightness. Is a color with 9.0 or more and saturation of 1.0 or less.

[White resin layer 2w]
The white resin layer 2w is formed as a layer containing at least a white pigment in a resin binder as a coloring pigment for expressing a white color.
In the present embodiment, the white resin layer 2w uses a white pigment as a color pigment in order to express white in the light shielding layer 2, and a photosensitive resin is used as the resin of the resin binder. Therefore, in the present embodiment, the white resin layer 2w is formed as a layer containing a white pigment as a coloring pigment in a resin binder made of a cured product of a photosensitive resin.

(Thickness)
The thickness of the white resin layer 2w is, for example, 1 to 40 μm, usually 10 to 30 μm. The white resin layer 2w is often less light-shielding than the black color, and in this respect, the white resin layer 2w is preferably thicker. However, when the thickness of the white resin layer 2w is increased and the light shielding property becomes too large, the transparent electrode 4 is extended from the display area A1 to the opaque area A2 across the step of the light shielding layer 2 including the white resin layer 2w. In some cases, disconnection may occur at the stepped portion. In this respect, the thickness of the white resin layer 2w is preferably as thin as possible, although the light shielding property is lowered.

However, even if the light shielding property of the white resin layer 2w is insufficient, the insufficient light shielding property can be compensated for by providing the backing layer 2b, and the white resin layer 2w can be made thinner accordingly. However, if the thickness of the white resin layer 2w becomes too thin, the fineness of the white design may be lowered. Therefore, the thickness of the white resin layer 2w is appropriately determined according to the color design expressed as the light shielding layer 2. Thickness is set.
In the present embodiment, the thickness of the white resin layer 2w is 30 μm.

(Multi-layer structure)
In the present invention, the white resin layer 2w is not shown, but may have a multilayer structure of two or more layers. Also in the present embodiment, the white resin layer 2w has a multilayer structure composed of two layers.
In the drawings according to the present invention, the white resin layer 2w is depicted as a single layer, but in these drawings, the white resin layer 2w may include a multilayer structure.
By forming the white resin layer 2w into a multi-layer structure, even if it is difficult to obtain a target thickness by a single formation, it is possible to obtain a target thickness. For example, as in the present embodiment, the white resin layer 2w is formed by a photolithography method using a white photosensitive resin composition.

  In the present invention, the backing layer 2b other than the white resin layer 2w, the yellowing prevention layer 3 and the like may also have a multilayer structure. The notation in each figure of the layers other than the white resin layer 2w is the same as that of the white resin layer 2w, and even if it is drawn as a single layer in the drawing, it may include a multilayer structure.

(Colored pigment: white pigment, etc.)
The color pigment used for the white resin layer 2w uses at least a white pigment in order to express a white color as the light shielding layer 2. As the color pigment, a chromatic color pigment other than a white pigment, an achromatic black pigment, and the like may be used in combination. The color pigments may be used alone, or a plurality of color pigments of the same type or different colors may be used.

  Examples of white pigments that can be used include titanium oxide, silica, talc, kaolin, clay, barium sulfate, and calcium hydroxide.

As the chromatic color pigment, for example, a red pigment, a yellow pigment, a blue pigment, a green pigment, and a purple pigment can be used. For example, red pigments such as diketopyrrolopyrrole, anthraquinone, and perylene can be used as the red pigment, and yellow pigments such as isoindoline and anthraquinone can be used as the yellow pigment. For example, blue pigments such as copper phthalocyanine and anthraquinone can be used as the blue pigment, and green pigments such as phthalocyanine and isoindoline can be used as the green pigment. Can use a quinacridone-based purple pigment.
As the black pigment, for example, titanium black (low-order titanium oxide, titanium oxynitride, etc.), carbon black, or the like can be used.

  The color pigment content depends on the color expressed by the light shielding layer 2 including the white resin layer 2w as an essential constituent layer, but the color pigment relative to the total solid content of the white resin layer 2w including the color pigment and the resin binder. The pigment concentration expressed as a percentage of the amount is, for example, 10 to 80%.

(Resin binder: photosensitive resin, etc.)
The resin of the resin binder is basically not particularly limited, but it is preferable to use a curable resin in terms of durability. When a curable resin is used as the resin of the resin binder, the white resin layer 2w is formed as a layer made of a cured product of the curable resin.
As the curable resin, a photosensitive resin that can be cured by an active energy ray such as an ultraviolet ray, an electron beam, or a visible ray can be used. By using a photosensitive resin, it can be formed by a photolithography method capable of forming a fine pattern.

  Examples of the photosensitive resin include one of photosensitive resins having a photoreactive group such as a reactive vinyl group such as an acrylic resin, an epoxy resin, a polyimide resin, a polyvinyl cinnamate resin, and a cyclized rubber. More than seeds can be used. In the acrylic resin, for example, a photosensitive resin composed of an alkali-soluble resin, a polyfunctional acrylate monomer, a photopolymerization initiator, and other additives can be used as a resin component of the resin binder.

As the alkali-soluble resin, one or more kinds of methacrylic acid ester copolymers such as benzyl methacrylate-methacrylic acid copolymer, cardo resins such as epoxy acrylate having a bisphenol fluorene structure, and the like can be used.
Examples of the polyfunctional acrylate monomers include trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and the like. The above can be used.
In the present invention, (meth) acrylate means either methacrylate or acrylate.

  As the photopolymerization initiator, one or more alkylphenone series, oxime ester series, triazine series, titanate series and the like can be used.

  In addition to the above, the resin binder can contain various known additives such as a solvent, a photosensitizer, a dispersant, a surfactant, a stabilizer, and a leveling agent.

(Formation of white resin layer 2w)
The white resin layer 2w can be formed, for example, by a photolithography method using a white photosensitive resin composition containing at least a white pigment and an uncured photosensitive resin as a color pigment.
The method of applying the white photosensitive resin composition on the surface of the translucent substrate 1 is, for example, a known coating method such as a spin coating method, a roll coating method, a die coating method, a spray coating method, or a bead coating method. be able to.
After the white photosensitive resin composition is applied, patterning is performed through a predetermined process such as exposure, development, baking (heat treatment), etc. using a photolithography technique, so that the surface of the translucent substrate 1 is coated. The white resin layer 2w having a predetermined pattern can be formed on the part.
In the present embodiment, the white resin layer 2w is formed by a photolithography method.

  In the present invention, the white resin layer 2w may be formed by a method other than the photolithography method, for example, a printing method such as screen printing or ink jet printing. can get.

[Backing layer 2b]
The backing layer 2b is a layer having a greater light shielding property than the white resin layer 2w. The backing layer 2b is formed so as to overlap the white resin layer 2w. The overlapping of the backing layer 2b and the white resin layer 2w shields light from a direction perpendicular to one surface (second surface S2 in the present embodiment) of the translucent substrate 1 on which the light shielding layer 2 is formed. When the layer 2 is observed, it means the overlapping of the respective patterns of the backing layer 2b and the white resin layer 2w. In other words, it means the overlap of the respective planar view patterns.
The backing layer 2b is preferably provided because the white resin layer 2w alone can supplement the light shielding property when the light shielding property of the light shielding layer 2 is insufficient. In particular, in the case of a white color that is difficult to obtain light shielding properties unless the thickness is increased, the effect of assisting light shielding by the backing layer 2b is great.

  As the backing layer 2b, for example, a low-reflection dark color layer or a reflective layer can be used. The dark color layer exhibits black or the like and absorbs light to improve the light shielding property, and the reflective layer reflects light to improve the light shielding property. Here, the “dark color” includes, in addition to black, for example dark blue such as amber and black with color.

As the dark color layer, a black resin layer containing, for example, a black pigment as a coloring pigment in a resin binder can be used. As the coloring pigment, the resin binder, and the forming method, those described in the white resin layer 2w can be appropriately adopted.
In the present embodiment, the backing layer 2b is formed as a black resin layer by a photolithography method in the same manner as the white resin layer 2w.

  As the reflective layer, for example, a metallic reflective layer made of a metal film containing silver, aluminum, or the like can be used.

The thickness of the backing layer 2b is usually less than the thickness of the white resin layer 2w. By setting the thickness of the backing layer 2b to be less than the thickness of the white resin layer 2w, it is possible to suppress the thickness of the entire light shielding layer 2 that includes the white resin layer 2w and tends to be thick.
The thickness of the backing layer 2b is, for example, 0.5 to 3 μm if the backing layer 2b made of a resin layer is black, and 0.05 to 0.5 μm in the case of the backing layer 2b made of a metallic reflective layer. it can.

(Metallic reflective layer)
In the present invention, when the backing layer 2b is formed as a reflective layer, a metallic reflective layer can be used for the backing layer 2b. Compared with a resin layer such as a black resin layer, the metallic reflective layer has an advantage that the whiteness of the light shielding layer 2 can be increased by making use of its light reflection characteristics. Hereinafter, the metallic reflective layer will be described.

The metallic reflective layer is a layer that includes one or more metal materials made of metal or a metal compound, exhibits metallic reflection in visible light, and is opaque and has a light shielding property larger than that of the white resin layer 2w. A metal layer can be used as the metallic reflective layer.
When the metallic reflective layer is achromatic such as silver or similar to achromatic, the whiteness of the white color design can be enhanced by the reflected light. Therefore, the thickness of the white resin layer 2w can be reduced accordingly.

  “Metallic reflection” means light reflectivity specific to a metal surface. Therefore, even if it is a metal, for example, the thing with a black surface can be made into the white color design which added the blackish to the white color expressed with the light shielding layer 2, and was light grayish. Further, if a metallic reflective layer having a chromatic color such as blue is used, the chromatic color can be added to the white color.

  The metal of the metal material is not particularly limited as long as it is light-reflective and exhibits a metallic color, that is, exhibits metallic reflection and becomes opaque in visible light. For example, metals such as silver, gold, copper, tin, chromium, platinum, aluminum, palladium, molybdenum, nickel, and alloys thereof can be used. As these metal compounds, metal oxides, nitrides, carbides, and the like can be used. As specific examples, a silver alloy (also referred to as APC) made of silver, palladium, and copper, aluminum, chromium, or the like can be used.

As for the reflectivity of the metallic reflective layer, for example, the reflectivity is preferably 70% or more in the sense that the reflectivity is 20% or more and the effect of enhancing the whiteness of the color by reflected light is great.
The reflectance is a numerical value representing the ratio of the total reflected light intensity of the specular reflected light intensity and the diffuse reflected light intensity to the incident light intensity perpendicularly incident on the surface of the metallic reflective layer as a percentage.
In the case of a normal metallic reflective layer such as aluminum or silver, a thickness of about 300 nm and a reflectance of 70% or more can be easily realized.

  The opacity in the metallic reflective layer is preferably 0.1% or less (optical density OD3.0 or more) in terms of total light transmittance, more preferably 0.01% or less (optical density OD4) in terms of total light transmittance. 0 or more), but at a minimum, it means that the total light transmittance is 1% or less (optical density OD2.0 or more).

In order to form the metallic reflective layer in the pattern shape of the backing layer 2b, the metallic reflective layer is once formed as a metal layer and then patterned by photolithography and etching to form a predetermined pattern. be able to.
The metal reflective layer can be formed as a metal layer by a known film forming method. For example, physical vapor deposition methods such as sputtering, vapor deposition, ion plating, chemical vapor deposition such as CVD (Chemical Vapor Deposition), vapor deposition such as coating, or coating methods. .
Even if the thickness of the metallic reflective layer is generally 500 nm, it is possible to ensure sufficient light shielding properties, and 1 μm is not necessary in terms of light shielding properties. For this reason, the thickness of the metallic reflective layer can usually be formed at about 10 to 300 nm.

Metallic reflective layers are usually conductive because they are light reflective or exhibit metallic reflection. Therefore, a metallic reflective layer is provided as the backing layer 2b on the side farthest from the translucent substrate 1 among the constituent layers of the light shielding layer 2, that is, on the back side, and conductors such as wiring and transparent electrodes 4 are provided on the surface of the light shielding layer 2. When providing, it is preferable to provide an insulating layer on the surface of the metallic reflective layer. When the conductor is in contact with the side surface of the metallic reflective layer, it is preferable to provide an insulating layer so as to cover the surface of the metallic reflective layer including the side surface.
This is because, for example, when a part of or all of the touch panel function is integrated on the light shielding layer 2 in the opaque region A2 afterwards by providing a conductor of the wiring or the transparent electrode 4, the portion of the metallic reflective layer This is because the front protective plate 10 for a display device can be used as an insulating circuit board without short-circuiting the conductor such as the wiring and the transparent electrode 4. However, in the present invention, it is not excluded that the metallic reflective layer is non-conductive.

  When the metallic reflective layer provided as the backing layer 2b is conductive, the yellowing prevention layer 3 can be employed as the insulating layer as shown in FIG. By using the yellowing prevention layer 3 as an insulating layer for the metallic reflective layer, an additional insulating layer can be eliminated. This can be said to be a configuration utilizing the fact that the yellowing prevention layer 3 is always electrically insulating since the yellowing prevention layer 3 also has a function of serving as an invisible layer.

(Metallic resin layer)
In the present invention, a metallic resin layer in which a metallic material is dispersed in a transparent resin binder as particles can be used as the reflective layer as a resin layer similar to the metallic reflective layer. However, the metallic resin layer is often inferior to the metal layer in terms of light shielding properties, and the thickness tends to be thick in order to achieve light shielding properties. For this reason, if the thickness is allowed, a metallic resin layer can be used as the metallic reflective layer.
The metal material constituting the particles of the metal material is not particularly limited as long as it shows metallic reflection. For example, metals such as aluminum, gold, silver, copper, tin, chromium, nickel, and alloys thereof are used. be able to.
As the resin of the transparent resin binder, for example, an acrylic resin, an epoxy resin, a polyester resin, a polyimide resin, or the like can be used.
The metallic resin layer can be formed as a solidified product obtained by drying and removing the solvent by an ink made of a liquid resin composition containing metal material particles, a transparent resin binder, a solvent, and the like.

[Yellowing prevention layer 3]
The yellowing prevention layer 3 is provided as a layer that suppresses yellowing of the white resin layer 2w and also serves as an invisible layer for the transparent electrode 4 that can be patterned in the display area A1. .

[Yellowing prevention function]
First, the yellowing prevention function of the yellowing prevention layer 3 will be described. In the present invention, “yellowing prevention” includes that yellowing can be prevented even a little. Therefore, prevention of yellowing is also referred to as suppression of yellowing.
The yellowing prevention layer 3 prevents oxygen in the air from coming into contact with the white resin layer 2w in order to suppress the yellowing of the white resin layer 2w caused by insufficient light resistance. It preferably has a function. Therefore, the yellowing prevention layer 3 is formed as a layer covering the white resin layer 2w. The yellowing prevention layer 3 is preferably a layer having a low oxygen permeability.
As such a yellowing prevention layer 3, when the white-type resin layer 2w receives sunlight, it is preferable to show oxygen permeability small enough to suppress the alteration leading to yellowing.

The material and thickness of the yellowing prevention layer 3 are preferably the oxygen permeability [cm ³ / (m ² · d · atm)] of the layer under the conditions of JIS K7126-2 Method A, 23 ° C., 50% RH. It should be set to 1.0 or less, more preferably 0.1 or less.
If the oxygen permeability is too large, the yellowing prevention function may not be sufficiently obtained, and if it is too small, only an excessive performance is obtained.

[Mechanism for improving light resistance by yellowing prevention layer 3]
The yellowing prevention by the yellowing prevention layer 3 is considered to be due to the light resistance of the white resin layer 2w being improved by the yellowing prevention layer 3. Therefore, the mechanism by which the light resistance of the white resin layer 2w is improved by the yellowing prevention layer 3 will be considered here.
In the present invention, in order to improve the light resistance of the white resin layer 2w used for the light shielding layer 2, a transparent layer called the yellowing prevention layer 3 is provided on the side opposite to the direction in which the light hitting the white resin layer 2w comes. Provide. If it is a normal idea with respect to the measure for improving the light resistance of the white resin layer 2w, the light resistance is improved by providing, for example, an ultraviolet absorption layer having an ultraviolet absorption function on the side where the light comes from the white resin layer 2w. Will be improved. This ultraviolet absorbing layer is transparent to visible light because the color of the white resin layer 2w needs to be visible from the front side.
Surprisingly, however, the present inventors provide the light resistance of the white resin layer 2w by providing the yellowing prevention layer 3 on the side opposite to the direction in which the light comes, that is, on the back side of the white resin layer 2w. It was discovered accidentally that it can improve yellowing and can suppress yellowing, and it came to this invention.
Accordingly, the yellowing prevention layer 3 does not have a function of shielding light that causes yellowing due to light degradation of the white resin layer 2w. For this reason, the mechanism by which the light resistance of the white resin layer 2w is improved by providing the yellowing prevention layer 3 is unknown at this stage. However, the mechanism of the light resistance improvement by the yellowing prevention layer 3 can be imagined from the fact that the light resistance is actually improved by the yellowing prevention layer 3 provided on the back side of the white resin layer 2w. It is considered that the presence of oxygen in the air influences the light deterioration of the resin layer 2w as well as the light. That is, oxygen is supplied from the back side of the white resin layer 2w, and the photooxidation reaction of the substance in the white resin layer 2w is not promoted by the cooperative action of this oxygen and the light reaching from the front side. I think.

[Index of yellowing prevention performance]
The index of the yellowing prevention performance by the yellowing prevention layer 3 is not particularly limited in the present invention. Any index that shows that yellowing is prevented can be used. In this embodiment, as an index of yellowing prevention performance, the color difference ΔE ^* ab defined by JIS Z 8730 is determined to be small in the L ^* a ^* b ^* color system according to JIS Z 8729. As an index other than the color difference, for example, a change in color spectrum can be employed.
In this embodiment, specifically, measurement evaluation was performed as follows. That is, using the front protective plate 10 for a display device as a test piece, the color from the front side of the light shielding layer 2 was measured before and after the accelerated test by the light resistance tester, and the degree of yellowing was judged. .
As the light resistance tester, for example, a xenon long life fade meter FAL-25AX (manufactured by Suga Test Machine Co., Ltd.) can be used.
A commercially available colorimeter, a spectrophotometer, etc. can be used for colorimetry. As the light source at the time of color measurement, for example, the light source C or the light source D ₆₅ defined by CIE (International Commission on Illumination) can be used. The optical system at the time of color measurement can be SCI (including specular reflection light) or SCE (regular reflection light removal).

  The test time in the light resistance tester is usually 100 hours or longer, preferably 500 hours or longer, more preferably 1000 hours or longer. If the change in yellowing index is reduced by the yellowing prevention layer 3 within this time, it can be said that yellowing has been improved. Furthermore, if the change is within an allowable range, it can be said that yellowing prevention performance has been practically obtained.

Incidentally, in this embodiment, the results shown in Table 1 were obtained by using an inorganic layer of niobium pentoxide (Nb ₂ O ₅ ) formed by vapor phase growth as the yellowing prevention layer 3. That is, in the configuration in which the yellowing prevention layer 3 is not provided, the color difference ΔE ^* ab is 4.95, whereas in the configuration of the present embodiment in which the yellowing prevention layer 3 is provided, the color difference ΔE ^* ab is It could be as small as 1.44.
The measurement is a value evaluated by the color difference ΔE ^* ab defined by JIS Z 8730 in the L ^* a ^* b ^* color system according to JIS Z 8729 under the SCI condition using the light source D65.

[Invisible function]
The yellowing prevention layer 3 is formed as a layer that also serves as an invisible layer. The invisible function as the invisible layer of the yellowing prevention layer 3 means that the pattern of the transparent electrode 4 formed in the display area A1 is visually observed when the front protective plate 10 for display device is observed from the front side. A function that makes it difficult to see.
In the present invention, “invisible” means not only that the pattern of the transparent electrode 4 is completely invisible with the naked eye, but also that the pattern of the transparent electrode 4 is visible in addition to this, but the invisible layer is not provided. Including that it is harder to see.

FIG. 2 is a diagram for explaining the principle that the pattern of the transparent electrode 4 becomes difficult to see by the yellowing prevention layer 3 that also serves as an invisible layer. Here, the “yellowing prevention layer 3” is also referred to as the “invisibility layer 3” in order to describe the invisibility function of the yellowing prevention layer 3.
The principle of making the transparent electrode 4 invisible by the invisible layer 3 is realized by adjusting the difference in refractive index between the two substances constituting the target substance interface.

First, the refractive indexes of the translucent substrate 1, the invisible layer 3 (yellowing prevention layer 3), the transparent electrode 4, and the resin layer 50 are defined as follows.
The refractive index of the translucent substrate 1 is n1,
The refractive index of the invisible layer 3 is n3,
The refractive index of the transparent electrode 4 is n4,
The refractive index of the resin layer 50 is n5.

Further, the specific refractive indexes of the translucent substrate 1, the invisible layer 3 (yellowing prevention layer 3), the transparent electrode 4, and the resin layer 50 are the following values for easy understanding of the explanation. Assume.
The refractive index n1 of the translucent substrate 1 = 1.5,
Refractive index n3 = 1.8 of the invisible layer 3
The refractive index n4 of the transparent electrode 4 = 2.0,
The refractive index n5 of the resin layer 50 = 1.5.
The refractive index is set such that the refractive index n3 of the invisible layer 3 is a refractive index between the refractive index n1 of the translucent substrate 1 and the refractive index n4 of the transparent electrode 4. That means
n1 <n3 ≦ n4 [Formula 1]
This setting satisfies the relationship.

In addition, the resin layer 50 is a thing when closely laminating | stacking with other members, such as the display panel 30, or the overcoat layer 7 etc. which consist of resin. Practically, this portion is rarely an air layer, so a more realistic resin layer 50 will be described.
In the present embodiment, the resin layer 50 is a component that is not included in the display device front protective plate 10. However, in the present invention, the resin layer 50 and the overcoat layer 7 are components that can be included in the front protective plate 10 for a display device.

  The intensity of light reflection at the substance interface is related to the refractive index difference Δn between the two substances constituting the substance interface, and increases as the refractive index difference Δn increases. Therefore, if attention is paid only to reducing light reflection at the interface, the refractive index n3 of the invisible layer 3 may be set so that the refractive index difference Δn becomes smaller. However, in the present invention, it is preferable to set the refractive index of the invisible layer 3 so that the reflectance at the pattern forming portion of the transparent electrode 4 and the reflectance at the non-forming portion are as equal as possible. .

First, FIG. 2A shows a conventional configuration in which the invisible layer 3 does not exist.
In the non-formed part where the pattern of the transparent electrode 4 is not formed, the refractive index difference Δn15 at the interface between the translucent substrate 1 and the resin layer 50 is 0.0 because the refractive indexes of both are equal. Therefore, the light L reaching this portion is transmitted without being reflected.
Next, the refractive index difference Δn14 at the interface between the translucent substrate 1 and the transparent electrode 4 is 0.5.
The refractive index difference Δn45 at the interface between the transparent electrode 4 and the resin layer 50 is 0.5.
Therefore, the difference ΔΔn between the refractive index difference in the formation part of the transparent electrode 4 and the refractive index difference in the non-formation part is 0.5. The difference ΔΔn between the refractive index differences of 0.5 becomes a difference in reflectance, and the pattern of the transparent electrode 4 is visually recognized by the naked eye.

Next, FIG. 2B shows a configuration in which the invisible layer 3 is present. FIG. 2B shows a form in which the invisible layer 3 exists between the transparent electrode 4 and the translucent substrate 1 in contact with both layers. Further, the invisible layer 3 is also present in the non-formed portion of the transparent electrode 4.
The interface that pays attention to the difference in refractive index is the surface with which the transparent electrode 4 is in contact. Therefore, the interface between the translucent substrate 1 and the invisible layer 3 is excluded.
The refractive index difference Δn35 at the interface between the invisible layer 3 and the resin layer 50 is 0.3,
The refractive index difference Δn34 at the interface between the invisible layer 3 and the transparent electrode 4 is 0.2,
The refractive index difference Δn45 at the interface between the transparent electrode 4 and the resin layer 50 is 0.5.
Therefore, the difference between the reflectance of the formation part of the transparent electrode 4 and the reflectance of the non-formation part is a linear approximation, and the difference ΔΔn between the maximum value of the refractive index difference in the formation part and the difference in refractive index in the non-formation part Considering, the difference ΔΔn between the refractive index difference in the formation part of the transparent electrode 4 and the refractive index difference in the non-formation part is a difference between the refractive index difference Δn35 and the refractive index difference Δn45, and ΔΔn is 0.2. . Therefore, ΔΔn = 0.5 in the conventional case of FIG. 2A where the invisible layer 3 does not exist can be reduced to 0.2. For this reason, the difference in reflectance between the formation part and the non-formation part of the transparent electrode 4 is reduced, and invisibility is achieved.

Next, FIG.2 (c) also shows the structure in which the invisible layer 3 exists. FIG. 2C shows a form in which the transparent electrode 4 exists between the invisible layer 3 and the translucent substrate 1 in contact with both layers. Further, the invisible layer 3 is also present in the non-formed portion of the transparent electrode 4.
Also in this case, the interface that pays attention to the difference in refractive index is the surface with which the transparent electrode 4 is in contact. Therefore, the interface between the invisible layer 3 and the resin layer 50 is excluded.
The refractive index difference Δn13 at the interface between the translucent substrate 1 and the invisible layer 3 is 0.3,
The refractive index difference Δn14 at the interface between the translucent substrate 1 and the transparent electrode 4 is 0.5,
The refractive index difference Δn43 at the interface between the transparent electrode 4 and the invisible layer 3 is 0.2.
Therefore, the difference ΔΔn between the refractive index difference in the forming part of the transparent electrode 4 and the refractive index difference in the non-forming part is a difference between the refractive index difference Δn13 and the refractive index difference Δn14, and ΔΔn is 0.2. Therefore, ΔΔn = 0.5 in the conventional case of FIG. 2A where the invisible layer 3 does not exist can be reduced to 0.2. For this reason, the difference in reflectance between the formation part and the non-formation part of the transparent electrode 4 is reduced, and invisibility is achieved.

Next, a case where the refractive index n3 of the invisible layer 3 is set equal to the refractive index n4 of the transparent electrode 4 will be described with reference to FIGS. 3 (a) and 3 (b). That means
n3 = n4 [Formula 2]
The case where n3 = n4 = 2.0 will be described.

FIG. 3A corresponds to the layer configuration of FIG. 2B, and the invisible layer 3 is in contact with both layers between the transparent electrode 4 and the translucent substrate 1. . Further, the invisible layer 3 is also present in the non-formed portion of the transparent electrode 4.
The refractive index difference Δn35 at the interface between the invisible layer 3 and the resin layer 50 is 0.5.
The refractive index difference Δn34 at the interface between the invisible layer 3 and the transparent electrode 4 is 0.0,
The refractive index difference Δn45 at the interface between the transparent electrode 4 and the resin layer 50 is 0.5.
Therefore, the difference ΔΔn between the refractive index difference in the formation part of the transparent electrode 4 and the refractive index difference in the non-formation part is a difference between the refractive index difference Δn35 and the refractive index difference Δn45, and ΔΔn is 0.0. For this reason, there is no difference in reflectivity between the formation part and the non-formation part of the transparent electrode 4, and theoretically complete invisibility is achieved. The refractive index difference Δn34 is 0.0, there is no optical interface, and light is transmitted without being reflected.
Such invisibility is that when layers with the same refractive index are stacked in contact with each other, both layers constituting the interface are not optically distinguished from each other, and both layers are single layers and partially different in thickness. It can be said that it is to be considered.

Next, FIG. 3B corresponds to the layer configuration of FIG. 2C, and the transparent electrode 4 exists between the invisible layer 3 and the translucent substrate 1 in contact with both layers. It is a form. Further, the invisible layer 3 is also present in the non-formed portion of the transparent electrode 4.
The refractive index difference Δn13 at the interface between the translucent substrate 1 and the invisible layer 3 is 0.5,
The refractive index difference Δn14 at the interface between the translucent substrate 1 and the transparent electrode 4 is 0.5,
The refractive index difference Δn43 at the interface between the transparent electrode 4 and the invisible layer 3 is 0.0.
In this configuration, the difference ΔΔn between the refractive index difference in the formation part of the transparent electrode 4 and the refractive index difference in the non-formation part is a difference between the refractive index difference Δn13 and the refractive index difference Δn14, and ΔΔn is 0.0 It is. For this reason, there is no difference in reflectivity between the formation part and the non-formation part of the transparent electrode 4, and theoretically complete invisibility is achieved.

Next, a case where the refractive index n3 of the invisible layer 3 is set larger than the refractive index n4 of the transparent electrode 4 will be described. That means
n3> n4 [Formula 3]
It is.
Here, the case where n3 = 2.3 is set will be described.

FIG. 4A corresponds to the layer configuration of FIG. 2B, and the invisible layer 3 is in contact with both layers between the transparent electrode 4 and the translucent substrate 1. . Further, the invisible layer 3 is also present in the non-formed portion of the transparent electrode 4.
The refractive index difference Δn35 at the interface between the invisible layer 3 and the resin layer 50 is 0.8,
The refractive index difference Δn34 at the interface between the invisible layer 3 and the transparent electrode 4 is 0.3,
The refractive index difference Δn45 at the interface between the transparent electrode 4 and the resin layer 50 is 0.5.
Therefore, the difference ΔΔn between the refractive index difference in the forming part of the transparent electrode 4 and the refractive index difference in the non-forming part is a difference between the refractive index difference Δn35 and the refractive index difference Δn45, and ΔΔn is 0.3. Therefore, ΔΔn = 0.5 in the conventional case of FIG. 2A where the invisible layer 3 does not exist can be reduced to 0.3. For this reason, the difference in reflectance between the formation part and the non-formation part of the transparent electrode 4 is reduced, and invisibility is achieved.

Next, FIG. 4B corresponds to the layer configuration of FIG. 2C, and the transparent electrode 4 exists between the invisible layer 3 and the translucent substrate 1 in contact with both layers. It is a form. Further, the invisible layer 3 is also present in the non-formed portion of the transparent electrode 4.
The refractive index difference Δn13 at the interface between the translucent substrate 1 and the invisible layer 3 is 0.8,
The refractive index difference Δn14 at the interface between the translucent substrate 1 and the transparent electrode 4 is 0.5,
The refractive index difference Δn43 at the interface between the transparent electrode 4 and the invisible layer 3 is 0.3.
Therefore, the difference ΔΔn between the refractive index difference in the forming part of the transparent electrode 4 and the refractive index difference in the non-forming part is a difference between the refractive index difference Δn13 and the refractive index difference Δn14, and ΔΔn is 0.3. Therefore, ΔΔn = 0.5 in the conventional case of FIG. 2A where the invisible layer 3 does not exist can be reduced to 0.3. For this reason, the difference in reflectance between the formation part and the non-formation part of the transparent electrode 4 is reduced, and invisibility is achieved.

By the way, conventionally, in the optical field, as a technique for reducing light reflection, a low refractive index layer having a relatively low refractive index and a high refractive index layer having a relatively higher refractive index than the low refractive index layer, Multilayer films that are alternately stacked are known.
However, in the present invention, as described above, the invisibility effect can be obtained even with a single layer. For this reason, it becomes possible to suppress an increase in cost, and to make invisible while preventing yellowing.
Moreover, since it is necessary to consider the decrease and increase of the light intensity due to interference between reflected light at the interface in the multilayer film, it is necessary to optimize the layer thickness in consideration of the light phase. In the case of a single-layer structure that does not use interference, the thickness of the layer can also be advantageously not restricted from the viewpoint of invisibility. This leads to a degree of design freedom that the thickness as the invisible layer 3 may be optimized in consideration of the yellowing prevention function as the yellowing prevention layer 3 and the like.

As described above, for the sake of clarity, the invisibility function has been described in terms of the relationship between the refractive index n3 of the invisible layer 3 and the refractive index of other layers, taking a hypothetical refractive index value as a specific example. In the present invention, the refractive index of each layer is not limited to these exemplified values. For example, the refractive index n1 of the translucent substrate 1 and the refractive index n5 of the resin layer 50 may be different.
In short, the refractive index n3 as the invisible layer 3 makes the light reflection intensity difference between the pattern forming portion and the non-forming portion of the transparent electrode 4 smaller than when the invisible layer 3 is not present. The refractive index is preferably set.

  In the above description, it has been described that it is more preferable to make the refractive index n3 of the invisible layer 3 equal to the refractive index n4 of the transparent electrode 4. However, in the present invention, even if the refractive index n3 and the refractive index n4 are not exactly equal, a similar effect can be obtained when they are equal if they are slightly different. In this respect, the refractive index difference Δn34 to Δn43 between the refractive index n3 and the refractive index n4 is usually preferably, although depending on the refractive index relationship with other layers such as the translucent substrate 1 and the resin layer 50. It is 0.1 or less, more preferably 0.05 or less, and still more preferably 0.03 or less.

In the above description, the case where the refractive index n3 of the invisible layer 3 is larger than the refractive index n1 of the translucent substrate 1 has been described. However, if the refractive index n3 is equal to the refractive index n1, In optical terms, the same layer as that of the translucent substrate 1 is simply stacked, and the invisible function is not exhibited.
Further, when the refractive index n3 is smaller than the refractive index n1, that is,
n3 <n1
In this case, since the refractive index n4 of the transparent electrode 4 that is larger than the refractive index n1 of the translucent substrate 1 is layered, a layer having a larger refractive index difference from the refractive index n4 of the transparent electrode 4 is overlapped. At this point, an increase in the refractive index difference will go against the invisibility.
For this reason, if the refractive index n3 of the invisible layer 3 is too large with respect to the refractive index n4 of the transparent electrode 4, a similar phenomenon occurs. For this reason, the refractive index n3 of the invisible layer 3 is set to be less than the refractive index difference Δ14 between the transparent substrate 1 and the transparent electrode 4 so that the refractive index difference Δn34 to Δn43 with the refractive index n4 of the transparent electrode 4 is less. Is preferred.
In summary, the refractive index n3 of the invisible layer 3 is
n1 <n3 <n4 + (n4-n1) [Formula 4]
Is preferable.

  In the above description, as a primary approximation, the pattern forming portion of the transparent electrode 4 has been described by focusing on the interface where the light reflection is greatest, that is, focusing on the interface that gives the largest refractive index difference. However, it is more preferable to consider the sum of the amounts of reflected light at both the front-side interface and the back-side interface of the transparent electrode 4, and the smaller refractive index difference at the other interface not taken into account in the description. Is more preferable.

(Evaluation wavelength of refractive index)
In the present invention, the refractive index is a refractive index in the visible light region, and the refractive index is evaluated with a wavelength of 550 nm, which is relatively sensitive to human eyes, as a wavelength representing the visible light region. The wavelength can be adopted. In the present invention, of course, the refractive index at other wavelengths may be considered. For example, the refractive index in the entire visible light range of 380 to 780 nm may be considered. The refractive index can be measured using a commercially available refractometer.

[Material of yellowing prevention layer 3 that also serves as an invisible layer]
The material of the yellowing prevention layer 3 is not particularly limited as long as it has a non-yellowing performance as well as a yellowing prevention performance. For example, as the yellowing prevention layer 3, one or more layers selected from an inorganic layer, a resin layer made of a resin, or an inorganic particle-containing resin layer containing inorganic particles in the resin can be appropriately selected.
Among these, from the viewpoint of yellowing prevention performance, an inorganic layer is preferable in that performance can be easily obtained even if the thickness is small. However, if the required performance is satisfied, a resin layer or an inorganic particle-containing resin layer may be used.
On the other hand, in view of the invisibility performance, those having a refractive index n3 larger than that of the translucent substrate 1 are preferable. Also in this respect, the inorganic layer is preferable in that the refractive index n3 can be easily set large. Moreover, the refractive index n3 can be easily set large by selection of the inorganic particle to contain also the inorganic particle containing resin layer.

(Inorganic layer)
The inorganic layer can be formed as a layer containing a metal compound. Not metal
By using a metal compound, electrical insulation and transparency as the invisible layer can be easily ensured. Examples of the metal compound include a metal oxide, a metal nitride, and a metal carbide. Alternatively, the inorganic substance in the inorganic layer may be a nonmetallic compound.
Examples of the inorganic material constituting the inorganic layer include silicon oxide, aluminum oxide, silicon oxynitride, silicon nitride, niobium pentoxide (Nb ₂ O ₅ ), and zirconium oxide. These can be formed singly or as a mixed layer of two or more. The refractive indexes of these metal compounds are, for example, 1.5 to 2.0 for silicon oxynitride, 1.8 to 2.1 for silicon nitride, 2.3 for niobium pentoxide, and 2.1 for zirconium oxide. .
Among these, niobium pentoxide is one type of inorganic material that is preferable in terms of excellent electrical insulation, transparency, film strength, film forming ability, and the like.

The inorganic layer can be formed by a known thin film forming method, for example, a physical or chemical vapor deposition method such as a vapor deposition method, a sputtering method, an ion plating method, or a CVD method.
When it is necessary to pattern the yellowing prevention layer 3 as the inorganic layer, it can be formed using a known etching resist and photolithography.
The thickness of the inorganic layer can be set to, for example, 0.05 to 0.5 μm.

(Inorganic particle-containing resin layer and resin layer)
The inorganic particle-containing resin layer is a layer containing inorganic particles in the resin. The inorganic particle-containing resin layer can reduce oxygen permeability and adjust the refractive index of the invisible layer to be higher than that of the resin, as compared to a simple resin layer that does not contain inorganic particles, due to the inclusion of inorganic particles. can do. As the inorganic particles, for example, particles listed in the inorganic layer can be used. As the resin, for example, a photosensitive resin listed in the white resin layer 2w, or a curable resin such as an epoxy resin, an acrylic resin, or a polyimide resin can be used.
As the resin layer, resins listed in the inorganic particle-containing resin layer can be used. A fluorine-containing resin can also be used.
When it is necessary to pattern-form the yellowing prevention layer 3 as an inorganic particle containing resin layer or a resin layer, it can form using a well-known photolithography method and a printing method. When pattern formation is unnecessary, a known coating method may be used.
The thickness of the inorganic particle-containing resin layer or the resin layer can be set to, for example, 0.5 to 10 μm.

〔Production method〕
Each layer constituting the front protective plate 10 for a display device of the present embodiment is formed as follows, for example. First, the white resin layer 2w and the backing layer 2b are pattern-formed in this order as the light shielding layer 2 in the region to be the opaque region A2 of the second surface S2 of the translucent substrate 1. Next, the yellowing prevention layer 3 is formed on the entire surface of the display area A1 and the opaque area A2 so as to cover both inner and outer side surfaces of the light shielding layer 2. Thus, the front protective plate 10 for display device is manufactured.

<< Second Embodiment: Integration of Touch Panel Function >>
A second embodiment of the front protective plate 10 for a display device according to the present invention will be described with reference to FIGS.

The present embodiment is the same as the first embodiment shown in FIG. 1 except for the following points. Therefore, the description of the same part is omitted.
a) The point where the transparent electrode 4 and the wiring 6 for touch panels are provided.
b) The overcoat layer 7 is provided.
c) The yellowing prevention layer 3 does not cover the outer side surface of the light shielding layer 2.

[Integration of touch panel function]
In the present invention, the front protective plate 10 for a display device may integrate a part or all of the touch panel function. For example, the transparent electrode 4 and the wiring 6 for touch panels may be further provided, and the translucent substrate 1 may also be used as the touch panel substrate. Integration with the touch panel function can be achieved by reducing the number of parts and reducing the thickness even if a part of the functions necessary for the touch panel is integrated. More preferably, they are integrated.

  In the present invention, when the front protective plate 10 for a display device is formed so as to integrate a touch panel function, in addition to the transparent electrode 4 and the wiring 6, other than the transparent electrode 4 and the wiring 6, for example, a connector or a control circuit. A part of the touch panel function may be integrated.

The front protective plate 10 for a display device that integrates part or all of the functions necessary as a touch panel can also be referred to as a “front protective plate for a touch panel integrated display device”. The front protective plate 10 for a display device that integrates all the functions necessary for a touch panel can also be called a touch panel. The front protective plate 10 for a display device in which a part of functions necessary as a touch panel is integrated can be said to be a touch panel constituent member.
In the case where the transparent electrode 4 for the touch panel is integrated, various position detection methods are known. However, in the position detection method in which the transparent electrode 4 can have two layers, at least one of these, more preferably two layers is used. It is desirable to integrate.
When the transparent electrode 4 is used for a touch panel, the position detection method may be a method other than the projected capacitance method, such as a resistance film method.

In the present embodiment, as an example of integration of the touch panel function, the transparent electrode 4 is a form example applicable to a capacitance method.
FIG. 5 is a plan view of the front protective plate 10 for a display device according to the present embodiment, FIG. 6 is a view showing an intersection of the transparent electrodes 4, FIG. 6 (a) is a plan view, and FIG. 7 is a cross-sectional view taken along the line CC in FIG. In these drawings, the yellowing prevention layer 3 is not shown in FIGS. 5 and 6.

[Yellowing prevention layer 3]
In this embodiment, the yellowing prevention layer 3 is formed on the entire surface including the display area A1 and the opaque area A2, and in the opaque area A2, the light shielding layer 2 including the white resin layer 2w and the backing layer 2b. In the display area A1, the transparent electrode 4 is formed between the transparent electrode 4 and the translucent substrate 1 in contact with the surface of the transparent electrode 4 on the translucent substrate 1 side. As a result, the pattern of the transparent electrode 4 is difficult to see, and the yellowing prevention layer 3 also serves as an invisible layer for the transparent electrode 4.
In the present embodiment, the yellowing prevention layer 3 that also serves as an invisible layer is formed as a continuous layer over the display area A1 and the opaque area A2 in a single formation step. Therefore, the yellowing prevention layer 3 and the invisible layer are simultaneously formed of the same material without an additional step.

[Coating on the side surface of the white resin layer 2w]
In the present embodiment, the yellowing prevention layer 3 does not cover the outer side surface among the side surfaces of the light shielding layer 2. Such a configuration may be used when it is not necessary to cover the outer side surface in terms of yellowing prevention performance.
Further, in the embodiments and modifications described below, examples of configurations in which the outer side surface is not covered with the yellowing prevention layer 3 are also exemplified, but these configuration examples are necessary in terms of yellowing prevention performance. In this case, of course, the outer side surface may be covered.
In the present invention, it is preferable that the yellowing prevention layer 3 covers at least the entire surface on the back side of the white resin layer 2w, and is formed so as to extend to the display area A1. The system resin layer 2w is preferably covered also on the inner side surface. Next, it is preferable that the outer side surface is also coated according to the need for yellowing prevention performance.

[Transparent electrode 4]
FIG. 5 is a plan view showing a pattern of the transparent electrode 4 in particular.
In the present embodiment, the transparent electrode 4 includes a first transparent electrode 4a and a second transparent electrode 4b that are formed to be insulated from each other.
The first transparent electrode 4a and the second transparent electrode 4b are formed of the same material in the present embodiment. Therefore, in the present specification, when these are collectively referred to, they are also simply referred to as “transparent electrode 4”.

In this embodiment, the touch panel structure which forms both the 1st transparent electrode 4a and the 2nd transparent electrode 4b on the same surface as the transparent electrode 4 for position detection of a touch panel is employ | adopted. That is, the first transparent electrode 4a and the second transparent electrode 4b are formed on the surface of the second surface S2, which is the same surface of the translucent substrate 1.
Various patterns are known for the pattern of the first transparent electrode 4a and the second transparent electrode 4b in the projection capacitive method, and there is no particular limitation. Typically, the plurality of first transparent electrodes 4a extend in the first direction, and the second transparent electrode 4b has a direction intersecting the first direction, usually a direction orthogonal thereto as the second direction. The pattern extends in the second direction. The same applies to the present embodiment as shown in the plan view of FIG.

FIG. 6A is a plan view showing an intersecting portion between the first transparent electrode 4a and the second transparent electrode 4b, and FIG. 6B is a cross-sectional view taken along the line CC in FIG. 6A. It is.
Intersections between the first transparent electrode 4 a and the second transparent electrode 4 b are insulated from each other by the interlayer insulating layer 5. The interlayer insulating layer 5 is necessary at least at the intersection of the first transparent electrode 4a and the second transparent electrode 4b.
Only one electrode of the first transparent electrode 4a and the second transparent electrode 4b, in the case of the figure, specifically, only the first transparent electrode 4a, the same surface in a pattern in which the intersection with the other electrode is missing Are formed at the same time, the interlayer insulating layer 5 is formed only at the intersection, and then the connecting portion 4aC is formed as a part of the first transparent electrode 4a across the interlayer insulating layer 5 to electrically connect the defective portion. Has been.

  In the cross-sectional view of FIG. 7 (a), since the transparent electrode 4 on the side close to the translucent substrate 1 is the first transparent electrode 4a, the intersection portion is formed after the first transparent electrode 4a is formed. The interlayer insulating layer 5 is formed at the intersection, and the second transparent electrode 4b corresponding to the connection portion 4aC is formed across the intersection and completed.

  The transparent electrode 4 composed of the first transparent electrode 4a and the second transparent electrode 4b extends from the position detection area in the central display area A1 to a portion overlapping the light shielding layer 2 in the opaque area A2, and is electrically connected to the wiring 6. It is connected to the.

A known material and a forming method can be employed for the transparent electrode 4.
In the present embodiment, the transparent electrode 4 is a transparent conductor film whose layer itself is transparent. Examples of the transparent electrode 4 made of a transparent conductive film include ITO (Indium Tin Oxide), InZnO (Indium Zinc Oxide), AlZnO (Aluminum Zinc Oxide), It is possible to use a patterned transparent conductor film such as InGaZnO (Indium Garium Zinc Oxide).

(Refractive index)
For example, ITO has a refractive index n4 of 1.7 to 2.2, usually 1.8 to 1.9, InZnO 1.9 to 2.4, and AlZnO. Is 1.9.
In the present embodiment, specifically, the transparent electrode 4 is made of ITO with a refractive index n4 = 2.0.

[Interlayer insulating layer 5]
Known materials and forming methods can be employed for the interlayer insulating layer 5. For example, when a resin is used for the interlayer insulating layer 5, an epoxy resin, an acrylic resin, a polyimide resin, or the like can be used, and specific examples include, for example, these resin-based photosensitive resins. Can be used. In the case of a photosensitive resin, it can be formed using a photolithography method. In addition, an inorganic material such as silicon oxide can be used for the interlayer insulating layer 5.

[Wiring 6]
A known material and formation method can be used for the wiring 6. For example, the wiring 6 can be made of metal (including alloys thereof) such as silver, gold, copper, chromium, platinum, aluminum, palladium, and molybdenum. The wiring 6 can be formed into a pattern by a photolithography method and an etching method after forming a metal layer of a silver alloy (also referred to as APC) made of silver, palladium, and copper by a sputtering method, for example.
For the wiring 6, a conductive layer (referred to as MAM) having a three-layer structure of molybdenum (Mo) / aluminum (Al) / molybdenum (Mo) can also be used.
In the present embodiment, the wiring 6 is formed of a silver alloy (also referred to as APC) made of silver, palladium, and copper using a photolithography method and an etching method as a metal layer.
In the present invention, the method for forming the wiring 6 is not particularly limited, and may be formed by a printing method such as a screen printing method or an ink jet printing method.

[Overcoat layer 7]
In this embodiment, the overcoat layer 7 is formed on the entire surface of the display area A1 and the opaque area A2 as the outermost layer on the surface of the second surface S2 of the translucent substrate 1.
In the present invention, the overcoat layer 7 can be omitted.

  For the overcoat layer 7, known materials and forming methods can be employed. The overcoat layer 7 is preferably a transparent resin, which is also a curable resin in terms of heat resistance. For example, an epoxy resin, an acrylic resin, a polyimide resin, and the like can be used. A thermosetting epoxy resin or the like can be used. In addition, as the curable resin, a photosensitive resin that is cured by ultraviolet rays or the like can be used. In the case of a photosensitive resin, a photolithography method can be used when partially forming. When not partially formed, the overcoat layer 7 can be formed by a coating method.

The overcoat layer 7 formed in contact with the transparent electrode 4 or the wiring 6 is insulative. The overcoat layer 7 formed on the wiring 6 does not form a portion where the wiring 6 is connected to the control circuit via a flexible printed circuit board (FPC), and the wiring 6 is exposed.
The overcoat layer 7 can improve insulation and scratch resistance.

  In the present invention, the overcoat layer 7 may be provided on the entire surface of the translucent substrate 1 including the opaque region A2 and the display region A1, or may not be provided on the entire surface, according to required specifications. May be.

〔Production method〕
Each layer constituting the front protective plate 10 for a display device of the present embodiment is formed as follows, for example. First, the white resin layer 2w and the backing layer 2b are patterned in this order as the light shielding layer 2 in the region to be the opaque region A2 of the second surface S2 of the translucent substrate 1. Next, the yellowing prevention layer 3 is formed on the entire surface of the display area A1 and the opaque area A2 so as to cover both inner and outer side surfaces of the light shielding layer 2.
Next, the wiring 6 is pattern-formed in the portion of the light shielding layer 2 that is the opaque region A2. Next, the transparent electrode 4 is patterned on the surface of the translucent substrate 1 and the surface of the light shielding layer 2 from the display region A1 to the opaque region A2. At this time, the transparent electrode 4 is patterned so as to be formed in contact with the wiring 6 formed on the surface of the light shielding layer 2. Next, the interlayer insulating layer 5 is patterned at the intersection of the transparent electrode 4, and the connecting portion 4 a C is formed by patterning the defective portion of the transparent electrode 4 across the interlayer insulating layer 5. Complete the whole. In this way, the front protective plate 10 for a display device in which the touch panel function is integrated is manufactured.

[Effect in this embodiment]
By using the front protective plate 10 for a display device having the above configuration, the white color design expressed by the light shielding layer 2 including the white resin layer 2w is hardly yellowed, and the pattern of the transparent electrode 4 In addition, it is possible to achieve a configuration in which both yellowing prevention and invisibility can be realized while suppressing the increase in cost.
Furthermore, since the touch panel function is integrated, the number of parts is reduced, the number of assembly steps is reduced, and the cost can be reduced.

<Deformation>
The front protective plate 10 for a display device of the present invention can take other forms other than the above-described forms. Some of these will be described below.

[Yellowing prevention layer 3 between white resin layer 2w and backing layer 2b]
In the present invention, as in the modification illustrated in FIG. 8, when the light shielding layer 2 also has the backing layer 2b, the yellowing prevention layer 3 may be provided between the white resin layer 2w and the backing layer 2b. . This is because there is no need to prevent yellowing of the backing layer 2b in a normal case.
With such a configuration, the degree of freedom in the layer formation order is increased, and a layer configuration according to the available manufacturing equipment can be obtained.

[Yellowing prevention layer 3 on the back side of the transparent electrode 4]
In the present invention, like the front protective plate 10 for a display device illustrated in FIG. 9, the yellowing prevention layer 3 that also serves as an invisible layer is formed on the transparent electrode 4 on the back side of the transparent electrode 4 in the display area A1. It may be formed in contact. Even in this form, invisible performance can be obtained.
In this case, as shown in FIG. 6 of the above embodiment, when the transparent electrode 4 has an intersecting portion and the yellowing prevention layer 3 on the transparent electrode 4 interferes with the electrical connection by the connecting portion 4aC, You may provide a through hole in the yellowing prevention layer 3 of a part. As described above, even when the yellowing prevention layer 3 is formed on the entire surface of the display region A1, such a form in which such a part that is not partially formed, such as a through hole, is included.
With such a configuration, the degree of freedom in the layer formation order is increased, and a layer configuration according to the available manufacturing equipment can be obtained.

[Anti-yellowing layer on the back side and front side of the transparent electrode]
In the present invention, like the front protective plate 10 for a display device illustrated in FIG. 10, the yellowing prevention layer 3 that also serves as an invisible layer is formed on the transparent electrode 4 on the back side of the transparent electrode 4 in the display region A1. In addition to being formed in contact, the transparent electrode 4 may be formed in contact with the transparent electrode 4 on the front side of the transparent electrode 4. The refractive index of the yellowing prevention layer 3 on both the back side and the front side of the transparent electrode 4 may be the same or different. Even in this form, invisible performance can be obtained.
With such a configuration, it is possible to achieve both a finer yellowing prevention function and a finer invisibility function.

[Layer structure of yellowing prevention layer 3 also used as an invisible layer]
In the said embodiment and deformation | transformation form, it demonstrated on the assumption that the yellowing prevention layer 3 which serves as an invisible layer is a single layer structure.
However, in the present invention, the yellowing prevention layer 3 that also serves as the invisible layer may have a multilayer structure. In particular, as the invisible layer, a function of attenuating reflected light by the light interference effect of the multilayer film may be used. For example, it is a multilayer film in which a low refractive index having a relatively low refractive index and a high refractive index layer having a relatively higher refractive index than that of the low refractive index layer are alternately laminated in total.
In such a multi-layer configuration, the cost increases because the number of layers increases compared to the single-layer configuration, but the invisibility performance can also be improved. However, since the yellowing prevention function as the yellowing prevention layer 3 and the invisibility layer for the transparent electrode 4 can be formed simultaneously with the same material, the yellowing prevention and invisibility can be realized together while suppressing the increase in cost. It can be set as the structure which can be performed.

[Use of transparent electrode 4 and wiring 6]
In the said embodiment, the use of the transparent electrode 4 and the wiring 6 was a touch panel. However, in the present invention, the use of the transparent electrode 4 and the wiring 6 may be other than the touch panel. For example, it may be used for sensors other than antennas and touch panels.

[Opaque area A2: visible information 8]
In the present invention, as shown by a dotted line in FIG. 1A, visible information 8 may be formed in the opaque region A2. The visible information 8 is any visually observable information such as a product logo, an operation explanation character, symbol, or pattern in the opaque area A2. Known materials and forming methods can be employed for the visible information 8.
For example, the visible information 8 can be formed by patterning a colored resin layer as a cured layer of a photosensitive resin containing a color pigment by a photolithography method or the like. Further, although not shown, the visible information 8 can also be provided as a pattern of a non-formed portion of the backing layer 2b provided on the back side of the white resin layer 2w.

[Opaque area A2: Window]
In the present invention, although not shown, a notification window, an infrared transmission window, or the like may be formed in the opaque region A2.

For example, in the case where the display device to which the front protective plate 10 for display device is applied is a mobile phone, the notification window indicates various operation states such as an incoming call and a charged state of a battery by blinking light, lighting, and color. This is the part that notifies the user. Known structures, materials, and forming methods can be employed for the notification window.
Although not shown, the notification window can be provided as a non-forming part of the light shielding layer 2, for example.

In the case of a mobile phone as the display device to which the front protective plate 10 for display device is applied, the infrared transmission window needs to prevent malfunction of the touch panel when the mobile phone is put on the ear during a call. From the viewpoint of extinguishing the display on the display panel and prolonging the battery life, it is provided in the front part of the infrared sensor provided as a human sensor for detecting the approach of human skin. The infrared transmission window has a light shielding property with respect to visible light and a transmission property with respect to infrared light. A well-known structure, material, and formation method can be adopted for the infrared transmission window.
Although not shown, the infrared transmission window can be provided as a non-forming part of the light shielding layer 2, for example.

[C] Display device:
The display device according to the present invention is a display device including at least a display panel and the display device front protective plate 10 disposed on the front side from which display light from the display panel is emitted.
When the display device front protective plate 10 is configured to have part or all of the touch panel function, the display device can have a touch panel function.
Although the display device front protective plate 10 does not have a touch panel function, when the display device has a touch panel function as another component, the display device can have a touch panel function.
When the front protective plate 10 for a display device is configured to have a part of the touch panel function, the display device has a touch panel function by providing the insufficient touch panel function as a separate component. And

<< First embodiment: Front protective plate for display device with integrated touch panel function: Part 1 >>
FIG. 11 shows an embodiment of a display device according to the present invention. A display device 100 shown in FIG. 11 includes a display device front protective plate 10 and a display panel 30 in order from the front side on the viewer V side above the drawing. ing.

[Front protective plate 10 for display device]
The display device front protective plate 10 in the present embodiment has a configuration in which a touch panel function is integrated.
The display device front protective plate 10 is the display device front protective plate 10 according to the present invention described above. More specifically, the front protective plate 10 for a display device further has a wiring 6 and a transparent electrode 4 as a touch panel function. Although not shown, the transparent electrode 4 is shown in FIGS. As in the front protective plate 10 for a display device exemplified in (1), the first transparent electrode 4a and the second transparent electrode 4b are provided.
The display device front protective plate 10 in the present embodiment is, for example, the display device front protective plate 10 of the second embodiment described above. In addition, in this embodiment, other components, such as a control circuit for functioning as a touch panel, can be further provided.

  Therefore, in addition to the transparent electrode 4 and the wiring 6 for the touch panel, the front protective plate 10 for the display device further integrates all the touch panel functions such as a control circuit and a connector for electrically connecting the control circuit and the wiring 6. It is also good. Of course, in this case, when using the display device front protective plate 10 in which all the functions of the touch panel are integrated, it is not necessary to provide the independent touch panel 20, and the display device front protective plate 10, the display panel 30, and the like. The display device is configured to include at least. In this form, the wiring, connector, control circuit, and the like on the outer periphery of the display panel 30 can be hidden.

[Display panel 30]
The display panel 30 is typically a liquid crystal display panel or an electroluminescent (EL) panel, but may be an electronic paper panel or a cathode ray tube, or various known display panels.

[Resin layer 50]
The resin layer 50 is a transparent layer, and an adhesive sheet, a solidified layer of the applied resin liquid, or the like can be used. As an adhesive sheet, what consists of an acrylic adhesive, a polyester adhesive, an epoxy adhesive, a silicone adhesive, etc. can be used. As the resin liquid, an acrylic photocurable resin or the like can be used.
The refractive index n5 of the resin layer 50 is usually 1.4 to 1.6.
By reducing the difference in refractive index at the interface with the resin layer 50, the light reflection is reduced, so that the display can be more easily seen.

[Effect in this embodiment]
By using the display device 100 configured as described above, the white color design expressed by the light shielding layer 2 including the white resin layer 2w is not easily yellowed in the front protective plate 10 for the display device. In addition, the pattern of the transparent electrode 4 is difficult to see, and further, it is possible to realize both the prevention of yellowing and the invisibility by suppressing the increase in cost.
Furthermore, since the touch panel function is integrated, the number of parts is reduced, the number of assembly steps is reduced, and the cost can be reduced.

«Second embodiment: Front protective plate for display device with integrated touch panel function: Part 2»
A display device 100 according to the second embodiment shown in FIG. 12 includes a display device front protective plate 10, a touch panel constituent member 20a, and a display panel 30 in order from the front side on the viewer V side above the drawing.

In the display device 100 according to the first embodiment illustrated in FIG. 11, the front protection plate 10 for a display device is a part of the touch panel function, and includes the wiring 6, the first transparent electrode 4 a and the second transparent electrode 4 b of the transparent electrode 4. By providing both, the touch panel function was integrated.
In the present embodiment, one of the first transparent electrode 4a and the second transparent electrode 4b of the transparent electrode 4 is provided with the display device front protective plate 10, and the other is provided with a separate substrate.

As illustrated in FIG. 12, in the display device 100 according to the present embodiment, the display device front protective plate 10 includes the first transparent electrode 4a, and the touch panel constituent member 20a as another substrate includes the second transparent electrode 4b. .
In a form that requires two layers of the first transparent electrode 4a and the second transparent electrode 4b that are insulated from each other, the position detection method of the touch panel by the transparent electrode 4 including the first transparent electrode 4a and the second transparent electrode 4b is: Although a projection type capacitance method may be used, other than the projection type capacitance method may be used.

  What is necessary is just to select the structure suitable for various conditions, such as the manufacturing equipment which can be used, an assembly process, as what structure the front surface protection plate 10 for display apparatuses and a touch panel function are integrated.

  Since the display panel 30 is the same as that of the first embodiment as the display device 100, description thereof is omitted.

[Effect in this embodiment]
By using the display device 100 configured as described above, the white color design expressed by the light shielding layer 2 including the white resin layer 2w is not easily yellowed in the front protective plate 10 for the display device. In addition, the pattern of the transparent electrode 4 is difficult to see, and further, it is possible to realize both the prevention of yellowing and the invisibility by suppressing the increase in cost.
Furthermore, since the touch panel function is integrated, the number of parts is reduced, the number of assembly steps is reduced, and the cost can be reduced.

<< Third embodiment: Front protective plate for a display device that does not integrate the touch panel function >>
In the present embodiment, the front protective plate 10 for a display device does not include the transparent electrode 4 and the wiring 6 for a touch panel, and the touch panel function is not integrated.
A display device 100 according to this embodiment shown in FIG. 13 includes a display device front protective plate 10, a touch panel 20, and a display panel 30 in order from the front side on the viewer V side above the drawing, and further includes a display device front protective plate. 10 and the touch panel 20 are filled with a resin layer 50.

As illustrated in FIG. 13, the display device 100 according to the present embodiment includes a display device front protective plate 10, a touch panel 20, and a display panel 30.
The touch panel 20 schematically shows the transparent electrode 4 and the wiring 6.
Since the display panel 30 is the same as that of the first embodiment of the display device 100, description thereof is omitted.

[Front protective plate 10 for display device]
The display device front protective plate 10 in the present embodiment has a configuration that does not have a touch panel function. For example, the transparent electrode 4 for applications other than the touch panel is provided for the display device front protective plate 10 of the first embodiment. The transparent electrode 4 is used for sensors other than antennas and touch panels, for example.
The display device front protective plate 10 can also include wiring 6 in the opaque region A2. The wiring 6 is connected to the transparent electrode 4.

[Touch panel 20]
The touch panel 20 is typically a projected capacitive touch panel capable of multi-touch (multi-point simultaneous input), but in addition, the front protection for a display device in which the translucent substrate 1 is used as a substrate. As long as the method is compatible with the plate 10, any of various known position detection type touch panels including a position detection method that does not require a transparent electrode, such as a surface capacitance method, an electromagnetic induction method, and an optical method may be used. .
The touch panel 20 has some opaque components such as a wiring, a control circuit, and a connector that electrically connects them on the outer periphery of the central position detection region. These opaque components are in a positional relationship between the touch panel 20 and the display device front protective plate 10 so as to overlap and hide the light shielding layer 2 in the opaque region A2 of the display device front protective plate 10 in plan view. It has become. For this reason, opaque components such as these wirings can be prevented from deteriorating the appearance of the display device 100.

[Effect in this embodiment]
By using the display device 100 configured as described above, the white color design expressed by the light shielding layer 2 including the white resin layer 2w is not easily yellowed in the front protective plate 10 for the display device. In addition, the pattern of the transparent electrode 4 is difficult to see, and further, it is possible to realize both the prevention of yellowing and the invisibility by suppressing the increase in cost.
Furthermore, since the touch panel 20 is integrated with the display device front protective plate 10 by the resin layer 50, the number of parts is reduced, the number of assembly steps is reduced, and the cost can be reduced.

<< Deformation as display device >>
The display device 100 of the present invention can take other forms besides the above-described form. Some of these will be described below.

[Form without touch panel]
The display device 100 in each of the above embodiments has a configuration having a touch panel function. However, in the present invention, the display device 100 may have a configuration not having a touch panel function, such as not having the touch panel 20. .
The effect of the front protective plate 10 for a display device that is incorporated in the display device 100 and does not have a touch panel function can be enjoyed. That is, in the front protective plate 10 for a display device, the white color design expressed by the light shielding layer 2 including the white resin layer 2w is hardly yellowed, and when the transparent electrode 4 is provided, the transparent electrode 4 is provided. The pattern 4 can hardly be seen, and the yellowing prevention and invisibility can be realized while suppressing the increase in cost.

[Interposition of resin layer]
The display device 100 according to the embodiment illustrated in FIGS. 12 and 13 has a structure in which an air layer exists between the display panel 30 and the touch panel constituent member 20a or between the touch panel 20 and an air layer. In the present invention, the space between these constituent members may be filled with a resin layer 50 such as an adhesive layer as described in the first embodiment illustrated in FIG. Since the light reflection on the surface of the member is reduced by the resin layer 50, the display can be more easily seen.

[D] Application:
Applications of the display device front protective plate 10 and the display device 100 according to the present invention are not particularly limited. For example, a mobile phone such as a smartphone, a portable information terminal such as a tablet PC, a personal computer, a car navigation device, a digital camera, a digital photo frame, an electronic book terminal, an electronic notebook, a game machine, an automatic ticket vending machine, an ATM terminal, a POS terminal, Vending machines.

DESCRIPTION OF SYMBOLS 1 Translucent board | substrate 2 Light-shielding layer 2b Backing layer 2w White resin layer 3 Yellowing prevention layer (invisible layer)
DESCRIPTION OF SYMBOLS 4 Transparent electrode 4a 1st transparent electrode 4aC Connection part 4b 2nd transparent electrode 5 Interlayer insulation layer 6 Wiring 7 Overcoat layer 8 Visible information 10 Front protective plate for display devices 20 Touch panel 20a Touch panel component 30 Display panel 40 (conventional) Front protective plate for display device 41 Translucent substrate 42 Light shielding layer 50 Resin layer 100 Display device 200 (Conventional) display device A1 Display region A2 Opaque region S1 First surface S2 Second surface V Observer

Claims (3)

A front protective plate for a display device having a central display area and an opaque area that is provided on the outer periphery of the display area and shields visible light,
A translucent substrate;
A light shielding layer provided in the opaque region on any one of the first surface of the translucent substrate and the second surface opposite to the first surface;
The light shielding layer has a white resin layer containing at least a white pigment in a resin binder,
Furthermore, on one surface of the translucent substrate, it has a yellowing prevention layer provided so as to cover the white resin layer,
The yellowing prevention layer is formed to extend to the display region, and also serves as an invisible layer that makes it difficult to see the pattern of the transparent electrode that can be formed in the display region.
Front protective plate for display devices. On one surface of the translucent substrate, the transparent electrode extends from the display region to the surface of the opaque layer in the opaque region,
The yellowing prevention layer is formed to extend from the opaque region having the white resin layer to the display region including the transparent electrode forming portion and the non-forming portion.
The front protective plate for a display device according to claim 1. A display panel;
The front protective plate for a display device according to claim 1 or 2, which is disposed on the front side from which display light from the display panel is emitted.
Comprising at least
Display device.

Images