JP7669766B2 - Decorative sheet, decorative member and display system - Google Patents

Description

This disclosure relates to decorative sheets, decorative members, and display systems.

As disclosed in Patent Document 1, a decorative sheet used for decoration is known. The decorative sheet of Patent Document 1 is placed over a display device. The decorative sheet conceals the display device when it is in a non-display state. The decorative sheet transmits image light emitted from the display device, enabling the image to be observed through the sheet.

Patent No. 6783413

A decorative sheet is required to have a certain degree of visible light transmittance to enable the image to be observed through the sheet. This causes the design displayed by the decorative sheet to have a somewhat whitish appearance. It is difficult to express a black design with conventional decorative sheets. The present disclosure aims to provide a decorative sheet that can display a black design.

The decorative sheet according to one embodiment of the present disclosure includes:
a black base layer containing a coloring material;
A reflection adjustment layer is laminated on the base layer and positioned on the outermost surface,
The luminous reflectance of the reflection adjustment layer is 3% or less,
The total light transmittance is 50% or less.

When the decorative sheet according to one embodiment of the present disclosure is placed facing the display surface of a display device, it may transmit image light emitted from the display surface, allowing the image displayed by the display device to be observed through the sheet.

In a decorative sheet according to one embodiment of the present disclosure, the total light transmittance may be a value measured in the area where the base layer is provided.

In a decorative sheet according to one embodiment of the present disclosure, the total light transmittance may be 10% or more.

In a decorative sheet according to one embodiment of the present disclosure, the absolute value of the slope of a straight line that is a first-order approximation of the light transmittance (%) for each wavelength (nm) from 410 nm to 650 nm at 1 nm intervals may be less than 0.046 (%/nm).

In a decorative sheet according to one embodiment of the present disclosure, the difference between the maximum and minimum light transmittance (%) for each wavelength (nm) from 410 nm to 650 nm in 1 nm increments may be 30% or less.

The decorative sheet according to one embodiment of the present disclosure may further include a design layer that displays a design and is located between the base layer and the reflection adjustment layer in the direction in which the base layer and the reflection adjustment layer are stacked.

In the decorative sheet according to one embodiment of the present disclosure, the design layer may contain an optical interference pigment.

In the decorative sheet according to one embodiment of the present disclosure, the design layer may include a pigment having a core material and a coating layer that coats the core material.

In the decorative sheet according to one embodiment of the present disclosure, the design layer may contain a pearl pigment.

A decorative member according to an embodiment of the present disclosure includes:
A decorative sheet according to an embodiment of the present disclosure;
The decorative sheet and a supporting portion laminated thereon are provided.

A first display system according to an embodiment of the present disclosure includes:
A decorative sheet according to an embodiment of the present disclosure;
A display device overlapped with the decorative sheet,
The display device has a display surface that faces the decorative sheet from the side opposite to the reflection adjustment layer.

A second display system according to an embodiment of the present disclosure includes:
A decorative member according to an embodiment of the present disclosure;
A display device overlapped with the decorative member,
The display device has a display surface that faces the decorative member from the side opposite to the reflection adjustment layer.

According to the present disclosure, a black design can be displayed using a decorative sheet.

FIG. 1 is a perspective view showing a display system for explaining an embodiment of the present invention. FIG. 2 is a plan view of the display system of FIG. 1, with the display device of the display system in a non-display state. FIG. 2 is a plan view of the display system of FIG. 1, with the display device of the display system in a display state. FIG. 4 is a cross-sectional view showing a display system, illustrating a modified example of a display device. FIG. 5 is a cross-sectional view showing an example of a decorative sheet that can be included in the display system of FIG. 1, and shows a layer structure of the decorative sheet. FIG. 6A is a cross-sectional view showing an example of a reflection adjustment layer that can be included in the decorative sheet of FIG. FIG. 6B is a cross-sectional view showing another example of the reflection adjustment layer that can be included in the decorative sheet of FIG. FIG. 6C is a cross-sectional view showing still another example of the reflection adjustment layer that can be included in the decorative sheet of FIG. FIG. 7 is a cross-sectional view showing an optical interference pigment of a design layer that can be included in the decorative sheet of FIG. FIG. 8 is a diagram showing an example of a method for manufacturing the decorative sheet of FIG. FIG. 9 corresponds to FIG. 5 and shows another example of the layer structure of the decorative sheet. FIG. 10 corresponds to FIG. 5 and shows still another example of the layer structure of the decorative sheet. FIG. 11 is a graph showing the transmittance spectra of Samples 1 to 4. FIG. 12 is a graph showing the transmittance spectrum of a design layer containing an optical interference pigment. FIG. 13 is a cross-sectional view showing a modified example of the decorative sheet. FIG. 14 is a cross-sectional view showing an example of a decorative member including a decorative sheet. FIG. 15 is a cross-sectional view showing another example of the decorative member. FIG. 16 is a cross-sectional view showing still another example of the decorative member.

An embodiment of the present disclosure will be described below with reference to the drawings. Note that in the drawings attached to this specification, the scale and aspect ratios have been appropriately altered and exaggerated from those of the actual objects for the convenience of illustration and ease of understanding.

Terms used in this specification that specify shapes and geometric conditions and their degrees, such as "parallel," "orthogonal," and "same," as well as values of lengths and angles, are not limited to their strict meanings, but are interpreted to include the range in which similar functions can be expected.

In this specification, terms such as "sheet," "film," and "plate" are not distinguished from one another solely on the basis of differences in name. For example, a "decorative sheet" cannot be distinguished from a member called a decorative film or decorative plate solely on the basis of differences in name.

To clarify the directional relationships between the drawings, common directions are indicated in several drawings by arrows with common symbols. The tip of the arrow is one side of each direction. An arrow pointing toward the viewer in a direction perpendicular to the surface of the drawing is indicated by a symbol with a dot in a circle, as shown in Figure 2, for example. An arrow pointing toward the viewer in a direction perpendicular to the surface of the drawing is indicated by a symbol with an x in a circle, as shown in Figure 4, for example.

Figures 1 to 16 are diagrams illustrating an embodiment. Figure 1 is a perspective view that shows a schematic diagram of a specific example of a display system. As shown in Figure 1, the display system 10 has a display device 20, and a decorative sheet 40 or a decorative member 30 that is layered on the display device 20. As described below, the decorative member 30 has a decorative sheet 40 and a support portion 35 that is layered on the decorative sheet 40. First, an example in which the display system 10 is formed by the display device 20 and the decorative sheet 40 will be described.

The display device 20 emits image light in the display state. In the display state, the display device 20 displays an image that can be observed by an observer on the display surface 21. In the non-display state, the display device 20 stops emitting image light.

The decorative sheet 40 is arranged to cover the display surface 21. The decorative sheet 40 is capable of transmitting image light from the display device 20. When the display device 20 is in a non-display state, the decorative sheet 40 conceals at least the display surface 21 of the display device 20. In this non-display state, the decorative sheet 40 displays a design as shown in FIG. 2. When the display device 20 is in a display state, the decorative sheet 40 allows for transparent observation of an image displayed by the display device 20 as shown in FIG. 3. In FIG. 3, a mark representing an umbrella is displayed. FIGS. 2 and 3 are plan views showing the display system 10 from the stacking direction in which the display device 20 and the decorative sheet 40 are stacked.

In one embodiment, the decorative sheet 40 is designed to enable a deep black design to be expressed. The embodiment will be described below with reference to the illustrated example. First, the display system 10 will be described, and then the manufacturing method of the decorative member 30 will be described.

As shown in FIG. 1, the display system 10 has a display device 20 and a decorative sheet 40. The display device 20 has a display surface 21. The decorative sheet 40 covers the display surface 21. The display system 10 can express a design using the decorative sheet 40. This decorative sheet 40 allows the display device 20 to be installed in harmony with the surrounding environment.

In the illustrated example, the display surface 21 has a rectangular shape in a plan view. The rectangular display surface 21 extends in a first direction D1 and a second direction D2. The display device 20 and the decorative sheet 40 are stacked in a third direction D3 that is normal to the display surface 21 and perpendicular to both the first direction D1 and the second direction D2. The third direction D3 is the stacking direction.

The display system 10 can be applied to various applications. The display system 10 may be applied to the interior or exterior of a mobile body, which is a movable device. Examples of mobile bodies include automobiles, ships, and airplanes. As a specific example, the display system 10 may be applied to the interior or exterior of an automobile. The display system 10 may be applied to walls, doors, ceilings, and the like as the interior of a building. The display system 10 may be applied to various devices such as furniture and home appliances. As a more specific example, the display system 10 may be applied to a desk. The display system 10 may be applied to the casing of equipment such as a refrigerator.

The display device 20 included in the display system 10 emits image light and displays an image on the display surface 21 in the display state shown in FIG. 3. The display device 20 stops emitting image light in the non-display state shown in FIG. 2. Various devices may be used as the display device 20.

The display device 20 may be a dot-matrix display device. A dot-matrix display device has a plurality of pixels that form each dot. In this display device, a desired image can be displayed on the display surface 21 by controlling the light-emitting state of each pixel. The display device 20 can display still images and moving images. Examples of such a display device 20 include a liquid crystal display device and an electroluminescence display device also called an EL display device. In the example shown in FIG. 1, the display device 20 includes a transmissive display panel 22 and a surface light source device 23 that illuminates the display panel 22 from behind in a planar manner. An example of the transmissive display panel 22 is a liquid crystal display panel. Various devices such as an edge-light type and a direct type may be used as the surface light source device 23.

Figure 4 shows another example of the display device 20. In the example shown in Figure 4, the display device 20 has a light-shielding panel 24 and a surface light source device 23. The light-shielding panel 24 has a transmission area 24a and a light-shielding area 24b. The light-shielding area 24b has visible light-shielding properties. The light-shielding area 24b may be formed of a resin containing a black pigment. The transmission area 24a may be an opening formed in a panel with visible light-shielding properties. The transmission area 24a may be a transparent portion. The pattern of the transmission area 24a is the same as the pattern of the image to be displayed by the display device 20. The light-shielding panel 24 forms the display surface 21. The light-shielding panel 24 is illuminated from behind in a planar manner by the surface light source device 23. When the light-shielding panel 24 is illuminated by the surface light source device 23, image light is emitted only from the area facing the transmission area 24a. This allows an image of a pattern corresponding to the transmission area 24a to be displayed.

As used herein, "transparent" means that the total light transmittance is 50% or more, and preferably 80% or more. "Visible light blocking" means that the total light transmittance is 30% or less, and preferably 10% or less. The total light transmittance is specified as a value measured using a haze meter ("HM-150N" manufactured by Murakami Color Research Laboratory Co., Ltd., compliant with JIS K 7361).

When the decorative sheet 40 is placed facing the display surface 21 of the display device 20, it transmits image light emitted from the display surface 21, allowing the image displayed by the display device 20 to be observed through the sheet. The total light transmittance of the decorative sheet 40 is 10% or more, preferably 15% or more, and more preferably 20% or more. By setting a lower limit for the total light transmittance of the decorative sheet 40, the decorative sheet 40 is given visible light transmittance, and sufficient visibility of the image displayed by the display device 20 can be ensured.

The decorative sheet 40 displays a design. The decorative sheet 40 imparts design to the display system 10. To enable the decorative sheet 40 to display a design, the total light transmittance of the decorative sheet 40 is 50% or less, preferably 45% or less, and more preferably 40% or less. Setting an upper limit to the total light transmittance of the decorative sheet 40 enables the decorative sheet 40 to express a richer range of designs, and can display designs in particularly deep black.

The thickness of the decorative sheet 40 in the third direction D3 is appropriately selected depending on the application of the decorative member 30. The thickness of the decorative sheet 40 in the third direction D3 may be 0.1 mm or more, or 0.2 mm or more. The thickness of the decorative sheet 40 in the third direction D3 may be 5 mm or less, or 3 mm or less.

The decorative sheet 40 has a reflection adjustment layer 42 and a base layer 44. The decorative sheet 40 may have layers other than the reflection adjustment layer 42 and the base layer 44. FIG. 5 shows an example of the layer configuration of the decorative sheet 40. In the example shown in FIG. 5, the decorative sheet 40 has, in order from the side closest to the display device 20 in the third direction D3, a second substrate layer 62, a base layer 44, a design layer 50, a bonding layer 64, a first substrate layer 61, a hard coat layer 46, and a reflection adjustment layer 42. At least the layers other than the base layer 44 and the design layer 50 are transparent.

The reflection adjustment layer 42 forms the outermost surface closest to the viewer in the third direction D3. The reflection adjustment layer 42 suppresses reflection of external light such as ambient light. Specifically, the luminous reflectance of the reflection adjustment layer 42 is 3% or less.

Luminous reflectance refers to the Y value of the tristimulus values (X, Y, and Z) in the XYZ color system (CIE1931). The tristimulus values are specified in JIS Z8701:1999. Luminous reflectance is determined by measuring the specular reflection of light incident at an angle of incidence of 10° from a D65 light source. A spectrophotometer (Shimadzu Corporation, product name: UV-2450) is used to measure luminous reflectance. The measurement wavelengths are 380 nm to 780 nm in 1 nm intervals.

The luminous reflectance of the reflection adjustment layer is the luminous reflectance taking into account the reflection at the outermost surface of the decorative sheet 40 formed by the reflection adjustment layer 42, the internal reflection of the reflection adjustment layer 42, and the reflection at the interface between the reflection adjustment layer 42 and the layer adjacent to the reflection adjustment layer 42 in the third direction D3. Therefore, in the decorative sheet 40 having the layer configuration shown in FIG. 5, the reflection at the interface between the reflection adjustment layer 42 and the air layer, the internal reflection of the reflection adjustment layer 42, and the reflection at the interface between the reflection adjustment layer 42 and the hard coat layer 46 are added together to be evaluated. For example, a sample for measuring the luminous reflectance is prepared by peeling off the first base layer 61 from the hard coat layer 46 in the third direction D3 and then attaching a black sheet having a refractive index equivalent to that of the hard coat layer 46 to the hard coat layer 46. Alternatively, the hard coat layer 46 is cut in the middle in the third direction D3, and a black sheet having the same refractive index as the hard coat layer 46 is attached to prepare a luminous reflectance measurement sample including the reflection adjustment layer 42, a part of the hard coat layer 46, and the black sheet. The luminous reflectance of the reflection adjustment layer 42 can be determined by measuring the prepared luminous reflectance measurement sample using the above-mentioned spectrophotometer.

It can be confirmed that the luminous reflectance of the reflection adjustment layer 42 is 3% or less even if the sample for measuring the luminous reflectance includes a layer that is not adjacent to the reflection adjustment layer 42. The luminous reflectance of a sample including a layer that is not adjacent to the reflection adjustment layer 42 is equal to or greater than the luminous reflectance of the reflection adjustment layer 42 because it has an extra reflection interface. Therefore, when the luminous reflectance of a sample including a layer that is not adjacent to the reflection adjustment layer 42, which is determined by the measurement using the above-mentioned spectrophotometer, is 3% or less, the luminous reflectance of the reflection adjustment layer 42 is also 3% or less. For example, when the luminous reflectance measured over the entire decorative sheet 40 is 3% or less, the luminous reflectance of the reflection adjustment layer 42 is also 3% or less. When the luminous reflectance of the first laminate 41A (see FIG. 8) obtained during the production of the decorative sheet 40 is 3% or less, the luminous reflectance of the reflection adjustment layer 42 is also 3% or less.

The reflection adjustment layer 42 may adopt various configurations capable of suppressing reflection. The reflection adjustment layer 42 may have the configurations shown in FIG. 6A to FIG. 6C. FIG. 6A shows a single-layer reflection adjustment layer 42. The reflection adjustment layer 42 shown in FIG. 6A is a low-refractive index layer 42a having a refractive index lower than that of the reflection adjustment layer 42 and the layer adjacent to the third direction D3 (hard coat layer 46 in the illustrated example). The reflection adjustment layer 42 shown in FIG. 6B has a low-refractive index layer 42a and a high-refractive index layer 42b in order from the outermost surface in the third direction D3. The reflection adjustment layer 42 shown in FIG. 6C has a plurality of low-refractive index layers 42a and a plurality of high-refractive index layers 42b. In the example shown in FIG. 6C, the low-refractive index layer 42a and the high-refractive index layer 42b are repeatedly arranged in order from the outermost surface side in the third direction D3. In the example shown in Figures 6A to 6C, the reflection adjustment layer 42 suppresses reflection by canceling out light reflected at different optical interfaces. The thickness and refractive index of the layers included in the reflection adjustment layer 42 can be appropriately selected according to the wavelength of light whose reflection is to be suppressed. The thickness of the low refractive index layer 42a and the high refractive index layer 42b included in the reflection adjustment layer 42 is less than 780 nm.

The low refractive index layer 42a and the high refractive index layer 42b can be produced by irradiating a layer of the applied liquid ultraviolet curing resin composition with ultraviolet light. The liquid ultraviolet curing resin composition for producing the low refractive index layer 42a may contain particles for adjusting the refractive index, such as hollow silica, an initiator, and a fluorine additive. The liquid ultraviolet curing resin composition for producing the high refractive index layer 42b may contain particles for adjusting the refractive index, such as a high refractive index filler, and an initiator. The low refractive index layer 42a and the high refractive index layer 42b can be produced by physical vapor deposition, such as vacuum deposition or sputtering.

The hard coat layer 46 provides the decorative sheet 40 with scratch resistance and impact resistance. The hard coat layer 46 may have excellent mechanical properties. The hard coat layer 46 is located between the reflection adjustment layer 42 and the design layer 50 and base layer 44 in the third direction D3. The hard coat layer 46 protects the design layer 50 and base layer 44 from the outside. The hard coat layer 46 may have a higher hardness than the design layer 50 and base layer 44, for example a higher Vickers hardness than the design layer 50 and base layer 44.

The hard coat layer 46 can be produced by irradiating an applied layer of a liquid ultraviolet curable resin composition with ultraviolet light. The liquid ultraviolet curable resin composition for producing the hard coat layer 46 may contain additives such as a filler in addition to an initiator. The additive may be an ultraviolet absorber. Such additives can improve the weather resistance of the hard coat layer 46. The thickness of the hard coat layer 46 may be, for example, 2 μm or more and 10 μm or less.

The first substrate layer 61 supports the reflection adjustment layer 42 and the hard coat layer 46. The first substrate layer 61 may be a film made of any of acrylic resin, polyethylene terephthalate, polycarbonate, and triacetyl cellulose, or may be a laminate in which such films are stacked. The thickness of the first substrate layer 61 may be, for example, 20 μm or more and 250 μm or less.

The bonding layer 64 is provided in the illustrated example in association with a manufacturing method described below. The bonding layer 64 bonds the first laminate 41A and the second laminate 41B described below. The bonding layer 64 can be formed using various adhesives or pressure-sensitive adhesives such as acrylic resins or epoxy resins. The thickness of the bonding layer 64 may be, for example, 5 μm or more and 80 μm or less.

The base layer 44 expresses the design that is the base of the decorative sheet 40. The base layer 44 in this embodiment is black. The color of the base layer 44 is visually judged to be black. The color of the base layer 44 is adjusted so that the L ^* value in the L ^* a ^* b ^* color system of the design displayed by the decorative sheet 40 is 30 or less, more preferably, the L ^* value is 10 or less. Preferably, the color of the base layer 44 is adjusted so that the a ^* value in the L ^* a ^* b ^* color system of the design displayed by the decorative sheet 40 is -1 or more and 1 or less. Preferably, the color of the base layer 44 is adjusted so that the b ^* value in the L ^* a ^* b ^* color system of the design displayed by the decorative sheet 40 is -1 or more and 1 or less.

The lightness L ^* value, lightness a* value, and lightness ^{b* value} in the L ^* a ^* b ^* color system of the design displayed by the decorative sheet 40 are specified as follows. First, a black sheet is attached to the surface of the decorative sheet 40 opposite the reflection adjustment layer 42 in the third direction D3 to prepare an evaluation sample. The evaluation sample is irradiated with light from the reflection adjustment layer 42 side, and the reflected light from the evaluation sample is measured to specify the L ^* value, lightness a ^* value, and lightness b ^* value. A spectrophotometer (Konica Minolta "CM-700d") is used to specify the L ^* value, lightness a ^* value, and lightness b ^* value. The values specified by this spectrophotometer are the L ^* value, lightness a ^* value, and lightness b ^* value. The black sheet used has a lightness L ^* value of 30 in the L ^* a ^* b ^* color system as determined using a spectrophotometer ("CM-700d" manufactured by Konica Minolta) in the same manner as the evaluation sample. The black sheet of the luminous reflectance measurement sample used when determining the luminous reflectance of the reflection adjustment layer 42 described above is also the same as the black sheet described here. That is, the black sheet of the luminous reflectance measurement sample has a lightness L ^* value of ³⁰ as determined using a spectrophotometer (" ^CM -700d" manufactured by ^Konica Minolta).

The base layer 44 has a coloring material. The coloring material is not particularly limited, and various coloring materials, such as pigments and dyes, may be used. As an example, the base layer 44 may contain a cyan pigment, a magenta pigment, and a yellow pigment to display a black design. Alternatively, the base layer 44 may contain a carbon block, which is a black pigment, and a cyan pigment to display a black design.

It is preferable that the color of the image observed through the decorative sheet 40 matches the color of the image displayed by the display device 20. In other words, it is preferable to suppress the color shift in which the color of the image changes as the image light passes through the decorative sheet 40. From the viewpoint of suppressing the color shift, it is preferable that the absolute value of the slope of the straight line that is a first-order approximation of the light transmittance (%) of the decorative sheet 40 at each wavelength (nm) in 1 nm increments from 410 nm to 650 nm is less than 0.046 (%/nm), and more preferably is 0.023 (%/nm) or less. It is preferable to select the color material contained in the base layer 44 so as to satisfy this condition. The light transmittance (%) of the decorative sheet 40 at each wavelength (nm) in 1 nm increments from 410 nm to 650 nm can be measured using an ultraviolet-visible-infrared spectrophotometer "V-670" (compliant with JIS K 0115) manufactured by JASCO Corporation.

Examples of the base material in which the coloring material of the base layer 44 is dispersed include acrylic resins such as polymethyl methacrylate, polyurethane resins, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-acrylic copolymers, chlorinated polypropylene resins, polyester resins, polyamide resins, butyral resins, polystyrene resins, nitrocellulose resins, and cellulose acetate resins. These materials may be used alone or in combination of two or more. The base layer 44 may be formed by printing a resin composition containing a base material and a coloring material. The base layer 44 produced as a printed layer may have a design expression that displays a background. For example, as a design that can harmonize the decorative sheet with the surrounding environment in which the display system 10 is installed, the base layer 44 may express a wood grain or marble pattern, texture, or geometric pattern by a black shading pattern or the like. The thickness of the base layer 44 may be, for example, 1 μm or more and 10 μm or less.

In the example shown in FIG. 5, the decorative sheet 40 has a design layer 50. As described above, the base layer 44 can express a black design. The design layer 50 can display pictures such as figures, patterns, designs, colors, pictures, photographs, characters, marks, pictograms, letters, and numbers. The design layer 50 can also express a design that displays a background. For example, the design layer 50 may display a wood grain or marble pattern, a metallic texture, or a geometric pattern as a design that can harmonize the decorative sheet with the surrounding environment in which the display system 10 is installed. In particular, the design layer 50 can display a design in a color other than black. That is, the design layer 50, together with the base layer 44, is responsible for the design expression of the decorative sheet 40. In this respect, the decorative layer of the decorative sheet 40 is composed of the design layer 50 and the base layer 44.

The design layer 50 includes a base material and a coloring material. Various pigments and dyes may be used as the coloring material. Examples of the base material in which the coloring material of the design layer 50 is dispersed include acrylic resins such as polymethyl methacrylate, polyurethane resins, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-acrylic copolymers, chlorinated polypropylene resins, polyester resins, polyamide resins, butyral resins, polystyrene resins, nitrocellulose resins, and cellulose acetate resins. These materials may be used alone or in combination of two or more. The design layer 50 may be formed as a printing layer by printing a resin composition containing a base material and a coloring material. The design layer 50 may be transferred onto, for example, the base layer 44 as a transfer layer. The thickness of the design layer 50 may be, for example, 0.5 μm or more and 10 μm or less.

In addition, a light interference pigment 51 may be used as a coloring material used in the design layer 50. The light interference pigment 51 expresses color by the interference of light. The light interference pigment 51 is different from general pigments that use light absorption or scattering in the color expression method. The light interference pigment 51 shown in FIG. 7 has a core material 52 and a coating layer 53 that covers the core material 52. In the example shown in the figure, the coating layer 53 has a first coating layer 53a and a second coating layer 53b. The core material 52 and the coating layer 53 are at least semi-transparent and have a light transmittance in the visible light range of preferably 50% or more, more preferably 70% or more. The light transmittance in the visible light range is specified as the average value of the light transmittance of each wavelength from 410 nm to 650 nm at 1 nm intervals measured using a UV-Visible-Infrared Spectrophotometer "V-670" (based on JIS K 0115) manufactured by JASCO Corporation.

As shown in Figure 7, light incident on the optical interference pigment 51 is reflected by the surface of the first coating layer 53a, the interface between the first coating layer 53a and the second coating layer 53b, and the interface between the second coating layer 53b and the core material 52. At this time, the light reflected from each surface interferes, and light of a specific wavelength is observed. The wavelength of light that is intensified by the interference changes depending on the observation direction. Therefore, design expression in different colors is realized depending on the observation direction.

The transmittance of the optical interference pigment 51 has a weak wavelength dependency. Therefore, the design layer 50 containing the optical interference pigment 51 can express the design in color while suppressing color shifts when observing the image displayed by the display device 20 through the decorative sheet 40.

In the example shown in FIG. 7, the core material 52 may be mica. The core material 52 may be a resin material, glass, or the like. The core material 52 may have a scale-like, flake-like, or flat shape so as to promote reflection and interference as shown in FIG. 7. Examples of the coating layer 53 include metal oxides, more specifically, oxides of metals such as titanium, iron, zirconium, silicon, aluminum, and cerium. The metal oxide may be a single type or a combination of two or more types.

The pearl pigment, which is an example of the optical interference pigment 51, may be oxide-coated mica, oxide-coated glass powder, or oxide-coated metal particles. Examples of oxide-coated mica include titanium mica, iron oxide-coated mica, iron oxide-coated mica titanium, and chromium oxide-coated mica titanium. Examples of oxide-coated glass powder include titanium oxide-coated glass powder and iron oxide-coated glass powder. Examples of oxide-coated metal particles include titanium oxide-coated aluminum powder.

In the illustrated example, the second substrate layer 62 supports the decorative layer including the base layer 44 and the design layer 50. The second substrate layer 62 may be a film made of any of acrylic resin, polyethylene terephthalate, and polycarbonate, or may be a laminate in which such films are stacked. The thickness of the second substrate layer 62 may be, for example, 20 μm or more and 250 μm or less.

The decorative sheet 40 having the layer structure shown in FIG. 5 can be produced by producing a first laminate 41A and a second laminate 41B, and bonding the first laminate 41A and the second laminate 41B using a bonding layer 64, as shown in FIG. 8. The first laminate 41A can be produced by producing a hard coat layer 46 and a reflection adjustment layer 42 in sequence on the first substrate layer 61. Any one or more of the hard coat layer 46 and the reflection adjustment layer 42 may be laminated to the first substrate layer 61 by transfer. The second laminate 41B can be produced by producing a base layer 44 and a design layer 50 in sequence on the second substrate layer 62. Any one or more of the base layer 44 and the design layer 50 may be laminated to the second substrate layer 62 by transfer. Either the first laminate 41A or the second laminate 41B may be produced first. The first laminate 41A and the second laminate 41B may be produced in parallel.

However, the layer structure shown in FIG. 5 and the manufacturing method shown in FIG. 8 are merely examples. A film containing coloring materials such as pigments and dyes may be used as the base layer 44. Examples of resin materials constituting the base film include acrylic resin, polyethylene terephthalate, and polycarbonate. By adopting this base layer 44, the second base layer 62 can be omitted from the second laminate 41B and the decorative sheet 40, as shown in FIG. 9.

The hard coat layer 46 and the reflection adjustment layer 42 may also be fabricated on the design layer 50, rather than on the first base layer 61. According to this example, the decorative sheet 40 is fabricated without going through a process of bonding the first laminate 41A and the second laminate 41B. According to this example, as shown in FIG. 10, the first base layer 61 and the bonding layer 64 can be omitted from the decorative sheet 40.

The operation of the illustrated display system 10 will be explained.

When the display device 20 is in a non-display state, the decorative sheet 40 covering the display surface 21 is observed, as shown in FIG. 2. In the illustrated example, the observer observes the design displayed by the design layer 50 and base layer 44 of the decorative sheet 40. The decorative sheet 40 forms an excellent design due to the rich expressive power of printing, etc. The design expression of the decorative sheet 40 allows the display device 20 to be installed while ensuring harmony and uniformity with the surrounding environment. The range of application of the display device 20 has been rapidly expanding in recent years, and by using the decorative sheet 40, the display device 20 can be applied to the interior of automobiles, the interior of buildings, furniture, home appliances, etc., where design is important.

When the display device 20 is in a display state, image light is emitted from the display surface 21. The image light emitted from the display surface 21 passes through the decorative sheet 40. As shown in FIG. 3, the image light that passes through the decorative sheet 40 allows the observer to observe an image formed on the display surface 21. In the example shown in FIG. 3, a mark representing an umbrella is displayed. The total light transmittance of the decorative sheet 40 is preferably 10% or more. By setting the lower limit of the total light transmittance in this manner, sufficient visibility of the displayed image can be ensured when observing an image displayed by the display device 20 through the decorative sheet 40.

In the present embodiment, the decorative sheet 40 expresses a design based on black through the base layer 44 when the display device 20 is in a non-display state. However, when a black design is displayed using a conventional decorative sheet, the design may take on a whitish tinge. As a result, it is not possible to fully express a deep black design, particularly a luxurious jet black design such as lacquerware decorated with lacquer. On the other hand, in the present embodiment, the decorative sheet 40 has a reflection adjustment layer 42 as the outermost surface on the observer side in the third direction D3. The luminous reflectance of the reflection adjustment layer 42 is 3% or less. By setting an upper limit on the luminous reflectance of the reflection adjustment layer 42 in this way, the decorative sheet 40 can display a deep black design. In addition, reflection on the decorative sheet 40 can be suppressed, making the design easier to observe. In addition, the total light transmittance of the decorative sheet 40 is 50% or less. Setting an upper limit on the visible light transmittance of the decorative sheet 40 also prevents the design from taking on a whitish tinge. As a result, when the display device 20 is in a non-display state, it is possible to produce a deep black color with a gloss that could not be achieved with conventional technology, that is, a jet black color, and also to conceal the display device 20.

Table 1 shows the results of an investigation into the effect of the reflection adjustment layer 42 on the visual reflectance. In this investigation, samples A to C of the decorative sheet 40 were produced. Samples A and B had a configuration in which the design layer 50 was omitted from the decorative sheet 40 shown in Figure 5. Sample C differs from samples A and B in that it omitted the reflection adjustment layer 42, but otherwise had the same configuration as samples A and B. The hard coat layer 46 was a cured product of an ultraviolet-curable resin made of acrylic resin. The refractive index of the hard coat layer 46 was 1.49, the same as the refractive index of the first base layer 61.

The reflection adjustment layer 42 of sample A was a single layer of a low refractive index layer 42a, which has a lower refractive index than the hard coat layer 46 shown in FIG. 6A. The low refractive index layer 42a had a base material that was a cured product of an ultraviolet-curable resin, and hollow silica dispersed in the base material. The refractive index of the low refractive index layer 42a was 1.30.

Sample B used a reflection adjustment layer 42 shown in FIG. 6C, which was formed by repeatedly arranging low-refractive index layers 42a and high-refractive index layers 42b. The low-refractive index layers 42a were made of silicon oxide by sputtering. The refractive index of the low-refractive index layers 42a was 1.45. The high-refractive index layers 42b were made of niobium pentoxide by sputtering. The refractive index of the high-refractive index layers 42b was 2.33.

For Samples A to C, before producing the decorative sheet 40, a black sheet was adhered to the first base layer 61 of the first laminate 41A and the visual reflectance was measured. The visual reflectance of Sample A was 1.5%. The visual reflectance of Sample B was 0.5%. The visual reflectance of Sample C was 5%. For Samples A and B, a deep black design with a jet black feel could be observed. For Sample C, the black design had a whitish tinge due to reflection on the outermost surface.

When an image displayed by the display device 20 is observed through the decorative sheet 40, a phenomenon known as color shift may occur in which the image is observed in a color different from the originally intended color. For example, if the base layer contains only the widely used carbon black as a coloring material and displays a black design, the image displayed by the display device 20 will have a somewhat reddish tinge.

The inventors of this invention have confirmed that setting an upper limit to the absolute value of the slope of a straight line that is a first-order approximation of the light transmittance (%) of each wavelength (nm) at 1 nm intervals from 410 nm to 650 nm is effective in suppressing color shift. Specifically, it is preferable to set this absolute value to less than 0.046 (%/nm), and more preferably to 0.023 (%/nm) or less. Note that human visual sensitivity to light outside the wavelength range from 410 nm to 650 nm drops significantly. Therefore, the wavelength range from 410 nm to 650 nm is the target.

Here, FIG. 11 is a graph showing the light transmittance spectrum for samples 1 to 4 of the decorative sheet 40. Samples 1 to 4 were made to have the layer structure shown in FIG. 5. The pigment used in the base layer 44 was changed between samples 1 to 4. However, the base layer 44 of samples 1 to 4 was all black. Samples 1 and 2 contained cyan pigment, magenta pigment, and yellow pigment. Sample 3 contained carbon black and cyan pigment. Sample 4 contained only carbon black. For samples 1 to 4, the light transmittance (%) of each wavelength (nm) at 1 nm intervals from 410 nm to 650 nm was linearly approximated. For samples 1 to 4, the relationship between the linearly approximated light transmittance y (%) and the wavelength (nm) was as follows. The approximation was performed using the least squares method, and a straight line was derived in which the square of the error was minimized.
Sample 1: y = -0.022x + 61
Sample 2: y = -0.019x + 62
Sample 3: y = -0.023x + 27
Sample 4: y = 0.046x-10
When the image displayed by the display device 20 was observed through the samples 1 to 4, only the sample 4, which had a slope of 0.046, was perceived as having a difference in color from when the image on the display device 20 was observed directly, that is, a color shift. For the samples 1 to 3, which had an absolute value of the slope of 0.023 or less, no color shift was perceived.

The difference between the maximum and minimum light transmittance (%) for each wavelength (nm) in 1 nm increments from 410 nm to 650 nm was greater for sample 3 than for sample 4. However, a larger difference can induce a color shift. From the perspective of suppressing color shifts, it is effective to set an upper limit for this difference. Specifically, it is preferable that the difference between the maximum and minimum light transmittance (%) for each wavelength (nm) in 1 nm increments from 410 nm to 650 nm be 30% or less, more preferably 25% or less, and even more preferably 10% or less.

The slope of the straight line approximating the distribution of light transmittance (%) for each wavelength (nm) and the difference between the maximum and minimum values of the distribution of light transmittance (%) for each wavelength (nm) can be adjusted by selecting the type of pigment contained in the base layer 44, combining pigments, etc. The slope of the straight line approximating the distribution of light transmittance (%) for each wavelength (nm) and the difference between the maximum and minimum values of the distribution of light transmittance (%) for each wavelength (nm) are influenced not only by the base layer 44 but also by the design layer 50. In this regard, it is preferable that the design layer 50 contains an optical interference pigment 51 for design expression.

Unlike pigments that express color through absorption, the optical interference pigment 51 has a more uniform transmission spectrum. As an example, FIG. 12 shows an example of the transmission spectrum of a design layer 50 containing a pearl pigment. In the graph of FIG. 12, the vertical axis represents light transmittance (%) and the horizontal axis represents wavelength (nm). As shown in FIG. 12, the transmittance is almost constant in the wavelength range of 410 nm to 650 nm, where humans have visual sensitivity. With a design layer 50 having such a transmission spectrum, it is possible to express the design in color while suppressing color shift when observing an image displayed by the display device 20 through the decorative sheet 40.

In the embodiment described above, the decorative sheet 40 has a black base layer 44 containing a coloring material, and a reflection adjustment layer 42 that is laminated with the base layer 44 and located on the outermost surface. In this decorative sheet 40, the luminous reflectance of the reflection adjustment layer 42 is 3% or less. By setting an upper limit on the luminous reflectance, it is possible to prevent the surface of the decorative sheet 40 from becoming white, and also to prevent reflections on the decorative sheet 40. In addition, the total light transmittance of the decorative sheet 40 is 50% or less. By setting an upper limit on the visible light transmittance of the decorative sheet 40, it is also possible to prevent the surface of the decorative sheet 40 from becoming white. As a result, when the display device 20 is in a non-display state, it is possible to conceal the display device 20 while expressing a dark black color with a gloss that could not be expressed conventionally, that is, a black color with a jet black feel.

In one specific example of the embodiment described above, the total light transmittance of the decorative sheet 40 is 10% or more. When observing an image displayed by the display device 20 through this decorative sheet 40, sufficient visibility of the displayed image can be ensured.

In one specific example of the embodiment described above, the absolute value of the slope of a straight line that is a first-order approximation of the light transmittance (%) for each wavelength (nm) from 410 nm to 650 nm in 1 nm increments is less than 0.046 (%/nm). According to this specific example, the gradient, i.e., the change, of the light transmittance at wavelengths of 410 nm or more and 650 nm or less is suppressed. Therefore, when an image displayed by the display device 20 is observed through the decorative sheet 40, color shift of the displayed image is suppressed. According to this display system 10, images can be displayed with high color reproducibility.

In one specific example of the embodiment described above, the difference between the maximum and minimum light transmittance (%) for each wavelength (nm) in 1 nm increments from 410 nm to 650 nm is 30% or less. According to this specific example, the variation in transmittance at wavelengths of 410 nm or more and 650 nm or less can be mitigated. Therefore, when an image displayed by the display device 20 is observed through the decorative sheet 40, the color shift of the displayed image is more effectively suppressed.

In one specific example of the embodiment described above, the decorative sheet 40 further includes a design layer 50 that is located between the base layer 44 and the reflection adjustment layer 42 in the third direction D3 and displays a pattern. The design layer 50 may contain an optical interference pigment 51. According to this specific example, absorption of image light in the design layer 50 due to the color material contained in the design layer 50 is suppressed. Therefore, the visibility of the image can be improved.

One embodiment has been described with reference to specific examples, but the above-mentioned specific examples do not limit the embodiment. The above-mentioned one embodiment can be implemented with various other specific examples, and various omissions, substitutions, changes, additions, etc. can be made within the scope of the gist of the embodiment.

Below, an example of a modification will be described with reference to the drawings. In the following description and the drawings used in the following description, parts that can be configured similarly to the above-mentioned specific example will be designated by the same reference numerals as those used for the corresponding parts in the above-mentioned specific example, and duplicated descriptions will be omitted.

The decorative sheet 40 may have a flat shape as shown in FIG. 1, or may have a three-dimensional shape, in other words, a three-dimensional shape, as shown in FIG. 13. In the example shown in FIG. 13, the decorative sheet 40 made into a flat shape is plastically deformed by molding. As an example, the decorative sheet 40 may be deformed by vacuum molding. The illustrated decorative sheet 40 is bent on both sides in the first direction D1. By imparting a three-dimensional shape to the decorative sheet 40 corresponding to various uses, the range of applications of the decorative sheet 40 is expanded.

As shown in FIG. 14, the decorative sheet 40 may be laminated with the support portion 35 to form the decorative member 30. In the display system 10 shown in FIG. 1, the decorative member 30 may be used instead of the decorative sheet 40. That is, the display system 10 may have the decorative member 30 and the display device 20 laminated with the decorative member 30. The decorative sheet 40 can be reinforced by the support portion 35, and the range of application of the decorative sheet 40 is expanded. Glass or a resin material can be used as a material for forming the support portion 35. Examples of the resin material include polycarbonate, acrylic resin such as polymethyl methacrylate, and ABS (acrylonitrile butadiene styrene copolymer). The support portion 35 may be bonded to the decorative sheet 40 via a bonding layer 39. The support portion 35 may be bonded to the decorative sheet 40 by welding.

The decorative sheet 40 may be used for insert molding. In insert molding, the decorative sheet 40 is accommodated in a cavity of a mold for molding, and injected resin is supplied to the cavity in which the decorative sheet 40 is accommodated. In insert molding, the decorative sheet 40 is welded to the support portion 35 as the molded portion 37 made of injected resin. As a result, a decorative molded product 31 having the support portion 35 made of the molded portion 37 and the decorative sheet 40 is obtained as the decorative member 30 shown in FIG. 14. Examples of thermoplastic resin materials constituting the molded portion 37 include polycarbonate, acrylic resins such as polymethyl methacrylate, and ABS (acrylonitrile butadiene styrene copolymer).

When the decorative sheet 40 is used for insert molding, the decorative sheet 40 may be preformed before the insert molding. An example of preformation is vacuum molding. For example, by using the preformed decorative sheet 40 shown in FIG. 13 for insert molding, the decorative molded product 31 shown in FIG. 15 is obtained as the decorative member 30. The decorative molded product 31 shown in FIG. 15 has the decorative sheet 40 and a support portion 35 consisting of a molded portion 37, and the support portion 35 is joined to the decorative sheet 40 by welding.

The decorative sheet 40 may be used for TOM molding. TOM molding is a three-dimensional overlay method in which the decorative sheet 40 is attached to a support part 35 having a three-dimensional shape. As shown in FIG. 16, a bonding layer 39 such as a heat seal layer may be provided between the support part 35 and the decorative sheet 40.

The layer structure of the decorative sheet 40 can be changed. For example, the design layer 50 may be omitted from the decorative sheet 40.

Although several variations on the specific examples described above have been described, it is also possible to combine multiple variations as appropriate.

D1: first direction, D2: second direction, D3: third direction, 10: display system, 20: display device, 21: display surface, 22: display panel, 23: surface light source device, 24: light shielding panel, 24a: transmission area, 24b: light shielding area, 30: decorative member, 31: decorative molded product, 35: support part, 37: molded part, 39: bonding layer, 40: decorative sheet, 41A: first laminate, 41B: second laminate, 42: reflection adjustment layer, 42a: low refractive index layer, 42b: high refractive index layer, 44: base layer, 46: hard coat layer, 50: design layer, 51: optical interference pigment, 52: core material, 53: coating layer, 53a: first coating layer, 53b: second coating layer, 61: first base material layer, 62: second base material layer, 64: bonding layer

Claims (11)

a black base layer containing a coloring material;
A reflection adjustment layer is laminated on the base layer and positioned on the outermost surface,
The luminous reflectance of the reflection adjustment layer is 3% or less,
The total light transmittance is 50% or less,
The decorative sheet has a total light transmittance of 10% or more. 2. The decorative sheet according to claim 1 , wherein the absolute value of the slope of a straight line obtained by first approximating the light transmittance (%) of each wavelength (nm) from 410 nm to 650 nm in 1 nm increments is less than 0.046 (%/nm). a black base layer containing a coloring material;
A reflection adjustment layer is laminated on the base layer and positioned on the outermost surface,
The luminous reflectance of the reflection adjustment layer is 3% or less,
The total light transmittance is 50% or less,
A decorative sheet, in which the absolute value of the slope of a straight line obtained by first approximating the light transmittance (%) of each wavelength (nm) from 410 nm to 650 nm in 1 nm increments is less than 0.046 (%/nm). 4. The decorative sheet according to claim 2, wherein the difference between the maximum and minimum light transmittances (%) at each wavelength (nm) in 1 nm increments from 410 nm to 650 nm is 30% or less. The decorative sheet according to any one of claims 1 to 4, further comprising a design layer that displays a design and is located between the base layer and the reflection adjustment layer in the direction in which the base layer and the reflection adjustment layer are stacked. a black base layer containing a coloring material;
A reflection adjustment layer is laminated on the base layer and positioned on the outermost surface,
The luminous reflectance of the reflection adjustment layer is 3% or less,
The total light transmittance is 50% or less,
The decorative sheet further comprises a design layer that displays a design and is located between the base layer and the reflection adjustment layer in the direction in which the base layer and the reflection adjustment layer are stacked. The decorative sheet according to claim 5 or 6 , wherein the design layer contains an optical interference pigment. The decorative sheet according to claim 5 , wherein the design layer contains a pigment having a core material and a coating layer that coats the core material. The decorative sheet according to any one of claims 1 to 8 ,
A decorative member comprising the decorative sheet and a supporting part laminated thereon. The decorative sheet according to any one of claims 1 to 8 ,
A display device overlapped with the decorative sheet,
The display device has a display surface that faces the decorative sheet from the side opposite to the reflection adjustment layer. The decorative member according to claim 9 ,
A display device overlapped with the decorative member,
The display device has a display surface that faces the decorative member from the side opposite to the reflection adjustment layer.

Images