Display panel device

Abstract

To improve, at low cost, the concealability of a pattern portion displayed by lighting of a light source while providing a function of diffusing light emitted from the light source in a display panel device including an interference pigment layer.SOLUTION: A concealment layer 40 has a pattern portion DP for displaying a first pattern, the pattern portion DP being configured to block first light (diffused light L16) emitted from an LED 10 serving as a light source to conceal the LED 10, and to transmit second light (diffused light L15) emitted from the LED 10 and transmitted through a light-diffusing resin sheet 20. The interference pigment layer 50 displays a second pattern different from the first pattern drawn by interference pigments by reflected light L24 of incident light L23 entering from outside the device. The interference pigment layer 50 is disposed at a position through which the light from the LED 10 that has passed through the light-diffusing resin sheet 20 and the pattern portion DP of the concealment layer 40 passes.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a display panel arrangement comprising an interference pigment layer. [Background technology]

[0002] In some conventional display panel devices, as described in Patent Document 1 (JP 2022-28602 A), a white diffusion sheet is provided between the LED (Light Emitting Diode) and the panel section. The LED in Patent Document 1 is a type of light source. The installation of the white diffusion sheet contributes to uniforming the LED light that passes through the panel section, and helps to make the display look beautiful. The diffusion sheet also serves to prevent the internal structure of the LED and other components from being seen through the panel section. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-28602 Summary of the Invention [Problem to be solved by the invention]

[0004] In a display panel device, even when a pattern is formed on the panel portion using an interference pigment, it is possible to provide a diffuser plate. Therefore, as shown in Fig. 9, the inventors of the present application have prototyped a display panel device 100 provided with a white diffuser plate 120 that diffuses light emitted from LEDs 110. In the display panel device 100 shown in FIG. 9, diffused light L11 emitted from the LEDs 110 and diffused by the diffuser plate 120 passes through the transparent resin sheet 130 and then passes through the pattern portion DP. Diffused light L12 emitted from the LEDs 110 and diffused by the diffuser plate 120 as shown in FIG. 7 is blocked by the concealing layer 140. The concealing layer 140 is, for example, black or a gray color close to black. By blocking the diffused light L12 by the concealing layer 140 and using the diffused light L11 that passes through the pattern portion DP, the display panel device 100 can display the pattern formed on the pattern portion DP by turning on the LEDs 110. For ease of understanding, the following description will be given assuming that a specific icon is formed as a pattern on the pattern portion DP.

[0005] When the LED 110 is not turned on and there is sufficient light illuminating the interference pigment layer 150 from outside the display panel device 100, in other words, when the light is bright enough to visually view the interference pigment layer 150, the display panel device 100 can display a pattern drawn with interference pigments on the interference pigment layer 150. For ease of understanding, the following description will be given of a wood grain pattern drawn with interference pigments. When the wood grain pattern is visible, as shown in Fig. 9, incident light L21 enters the interference pigment layer 150, and reflected light L22 colored by the interference pigment is emitted from the interference pigment layer 150. Here, the interference pigment used in the interference pigment layer 150 will be further described with reference to Fig. 10.

[0006] FIG. 10 schematically illustrates an example of the cross-sectional structure of a particle of an interference pigment 200. The interference pigment 200 has, for example, a core portion 201 and a thin shell portion 202 that covers the core portion 201. Both the core portion 201 and the shell portion 202 transmit visible light. The core portion 201 and the shell portion 202 are made of materials with different refractive indices. For example, the refractive index of the core portion 201 may be smaller than that of the shell portion 202. FIG. 10 illustrates the state in which incident light L211 and L212 are incident on the shell portion 202 of the interference pigment 200. Reflected light L221 is the incident light L211 reflected by the surface of the shell portion 202. Reflected light L222 is the incident light L212 reflected by the core portion 201 after traveling through the shell portion 202. 9. The reflected light beams L221 and L222 interfere with each other constructively, causing the interfering light beam of a specific wavelength to become stronger and produce a color. The incident light beams L211 and L212 in Fig. 10 correspond to the incident light beam L21 in Fig. 9, and the reflected light beams L221 and L222 in Fig. 10 correspond to the reflected light beam L22 in Fig. 9.

[0007] For example, if the thickness of the shell portion 202 is adjusted so that the wavelength that is intensified by interference is a blue wavelength, a blue interference pigment can be obtained. Visible light emitted from a light source (e.g., LED 110) is also incident on the interference pigment 200. For example, diffused light L11 incident on the interference pigment 200 in FIG. 10 is visible light emitted from the light source. The diffused light L11 is incident on the interference pigment 200, passes through the interference pigment 200, and exits the interference pigment 200 in the opposite direction. This diffused light L11 that has passed through the interference pigment 200 is the light that passes through the pattern portion DP in FIG. 9. A specific icon is displayed by the diffused light L11. Because the interference pigment 200 has the above-described properties, some of the incident light L21 incident on the interference pigment layer 150 from outside the device passes through the pattern portion DP and reaches the diffuser plate 120. Because of the presence of the incident light L213, the incident light L213 may be reflected by the diffuser plate 120, pass through the transparent resin sheet 130, the pattern portion DP, and the interference pigment layer 150, and generate reflected light L223 that is irradiated outside the device. In the prototype display panel device 100 shown in FIG. 9 , the color of the interference pigment 200 is weakened in the pattern portion DP where the diffuser plate 120 is present, because the base color of the interference pigment 200 is black (the hiding layer 140). In other words, the inventors of the present application discovered a problem in the display panel device 100 having the interference pigment layer 150: the use of the diffuser plate 120 makes the pattern portion DP visible even when the LED 110 is not lit, thereby degrading the design.

[0008] Incidentally, if an absorbing pigment were used instead of the interference pigment 200, the incident light L213 and the reflected light L223 would be absorbed by the absorbing pigment, eliminating the problem of visibility of the pattern portion DP when the LED 110 is not lit. However, if an absorbing pigment is used, the diffused light L11 would be absorbed by the absorbing pigment, making it difficult to display a specific icon. In other words, if an absorbing pigment is used, it would be difficult to selectively display a specific icon and a wood grain pattern by turning the LED 110 on and off. Furthermore, if various layers or sheets are added to solve the problem of the pattern portion DP being visible when using such a diffusion plate 120, the cost of the display panel device will increase.

[0009] The object of the present invention is to provide a display panel device equipped with an interference pigment layer that has the function of diffusing light emitted from a light source, while improving the concealment of a pattern portion that is displayed when the light source is turned on, at low cost. [Means for solving the problem]

[0010] Below, several aspects will be described as means for solving the problems. These aspects can be arbitrarily combined as necessary. A display panel device according to a first aspect includes a light source, a translucent light-diffusing resin sheet, a concealing layer, and an interference pigment layer. The light-diffusing resin sheet is disposed at a position where it is irradiated with light from the light source. The concealing layer and the interference pigment layer are provided on the light-diffusing resin sheet. The concealing layer blocks a first light from the light source to conceal the light source, and has a pattern portion for displaying a first pattern by transmitting a second light from the light source that has passed through the light-diffusing resin sheet. The interference pigment layer displays a second pattern that is different from the first pattern drawn by the interference pigment by reflected light incident from outside the device. The interference pigment layer is disposed at a position where the first light that has passed through the light-diffusing resin sheet and the pattern portion of the concealing layer passes through. According to the display panel device of the first embodiment, the light-diffusing resin sheet has the function of absorbing part of the light from the light source and the function of diffusing the light, so that the light-diffusing resin sheet can improve the concealment of the pattern part displayed when the light source is turned on while providing the function of diffusing the light irradiated from the light source. By using the light-diffusing resin sheet, it is possible to omit the conventional white diffusion sheet, and it is possible to suppress an increase in the manufacturing cost of the display panel device.

[0011] A display panel device according to a second embodiment is the display panel device according to the first embodiment, wherein the light-diffusing resin sheet is configured so that the total light transmittance (measured in accordance with JIS K7361-1) is 30% or less and 1% or more. According to the display panel device of the second aspect, it is possible to obtain an improved concealment property for the pattern portion. A display panel device according to a third aspect is the display panel device according to the second aspect, wherein the light-diffusing resin sheet has a total light transmittance of 5% or more. According to the display panel device of the third aspect, it becomes easier to obtain sufficient brightness to display the design portion when the light source is turned on. A display panel device according to a fourth aspect is a display panel device according to any one of the first to third aspects, wherein the light-diffusing resin sheet is configured so that the haze (measured in accordance with JIS K7136) is 30% or more and 100% or less. According to the display panel device of the fourth aspect, the brightness of the displayed pattern portion can be made sufficiently uniform when the light source is turned on, and the contrast between the pattern portion and the portion other than the pattern portion can be improved.

[0012] A display panel device according to a fifth aspect is a display panel device according to any one of the first to fourth aspects, wherein the color of the light-diffusing resin sheet (measured in accordance with JIS Z8722) is configured so that, in the SCE method, the L value is 0 or more and 30 or less, the a value is in the range of -5 to +5, and the b value is in the range of -5 to +5. According to the display panel device of the fifth embodiment, the hue does not change due to the light-diffusing resin sheet, so that the design portion can be displayed using the color of the light source. A display panel device according to a sixth aspect is the display panel device according to any one of the first to fifth aspects, wherein the light-diffusing resin sheet is based on polycarbonate resin. The display panel device according to the sixth aspect can easily obtain a strength sufficient for use in, for example, an automobile instrument panel. Note that "based on polycarbonate resin" means that the display panel device contains 50% by weight or more of polycarbonate resin. [Effects of the Invention]

[0013] The display panel device of the present invention has good design properties due to the interference pigment layer, and has the function of diffusing light emitted from the light source, while also improving the concealment of the pattern part displayed when the light source is turned on at low cost. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a schematic front view of an instrument panel for explaining a display panel device displaying icons and the like. [Figure 2]FIG. 1 is a schematic front view of an instrument panel for explaining a display panel device that does not display icons or the like. [Figure 3] 1 is a schematic cross-sectional view illustrating a configuration of a display panel device according to an embodiment. [Figure 4] 10 is a drawing-substitute photograph for illustrating the display when there is no light diffusion, when a white diffusion plate is used, and when a smoke-colored light diffusion resin sheet is used. [Figure 5] 1 is a photograph substituted for a drawing showing an example of the appearance of a transparent acrylic plate on which a concealing layer and an interference pigment layer are formed, and a light-diffusing resin sheet on which a concealing layer and an interference pigment layer are formed. [Figure 6] 1 is a photograph substituted for a drawing showing an example of the appearance of a light-diffusing resin sheet on which a concealing layer and an interference pigment layer are formed. [Figure 7] FIG. 10 is a schematic cross-sectional view showing an example of the configuration of a display panel device that does not perform light dispersion. [Figure 8] 10 is a schematic cross-sectional view showing the configuration of a display panel device according to Modification C. FIG. [Figure 9] FIG. 10 is a schematic cross-sectional view showing an example of the configuration of a prototype display panel device using a white diffusion plate. [Figure 10] FIG. 1 is a schematic diagram illustrating the difference in appearance between transmitted light and reflected light in an interference pigment. DETAILED DESCRIPTION OF THE INVENTION

[0015] (1) Examples of display panel device use 1 and 2 show an instrument panel 1 of an automobile. The instrument panel 1 is provided with meters such as a speedometer 2. The instrument panel 1 also includes a dashboard 3. A steering wheel 4 is disposed in front of the instrument panel 1. A display panel device 5 is disposed in the center of the instrument panel 1. A heater control panel 6 is disposed below the display panel device 5. In this embodiment, the display panel device 5 is even incorporated into the dashboard 3. The display panel device 5 incorporated into the dashboard 3 can display the characters "PASSENGER AIR BAG," "ON," and "OFF," as well as an icon 7 related to the airbag. FIG. 1 shows the instrument panel 1 in a state in which the icon 7 and other characters are displayed, and FIG. 2 shows the instrument panel 1 in a state in which the icon 7 and other characters are not displayed. When an LED 10 (see FIG. 3 ), which will be described later, is lit, the display panel device 5 displays the icon 7 and characters on the dashboard 3 as shown in FIG. 1. When the LED 10 (see FIG. 3 ), as shown in FIG. 2 , is turned off, the display panel device 5 displays a wood grain pattern 8 on the dashboard 3 using an interference pigment layer 50 (see FIG. 3 ), but does not display the icon 7 or characters on the dashboard 3. When the display panel device 5 is used in an automobile instrument panel 1, it may be necessary to provide the display panel device 5 with sufficient strength to prevent damage to the instrument panel 1 in the event of an accident. In such a case, it is preferable to use polycarbonate resin for the light diffusion resin sheet 20 (see FIG. 3) described below.

[0016] (2) Display panel device configuration As shown in FIG. 3, the display panel device 5 includes an LED 10 as a light source, a light diffusion resin sheet 20, a concealing layer 40, and an interference pigment layer 50. Here, an example in which the LED 10 is used as the light source will be described, but the light source may be a light source other than an LED. Light sources that can be used include, for example, electroluminescence (EL), fluorescent lamps, and incandescent lamps. In the display panel device 5, the LED 10, the light diffusion resin sheet 20, and the concealing layer 40 are arranged in this order. In this specification, the concept of "sheet" includes the concept of "plate." Under this definition, for example, a "light diffusion resin plate" would be considered a type of "light diffusion resin sheet." The light diffusion resin sheet 20 is disposed at a position where it is irradiated with light from the LEDs 10. Therefore, light L13 and L14 irradiated from the LEDs 10 enters the light diffusion resin sheet 20. The light diffusion resin sheet 20 has the function of partially absorbing the light from the LEDs 10 and the function of diffusing the light. Such a light diffusion resin sheet 20 is translucent. The color of the light diffusion resin sheet 20 is set, for example, by the SCE (Standard Color Expression) method, with an L value of 0 to 30, an a value in the range of -5 to +5, and a b value in the range of -5 to +5. Measurement of each value in the SCE method is performed in accordance with JIS Z 8722. In other words, the light diffusion resin sheet 20 exhibits a smoky color. Due to the light diffusion function of the light diffusion resin sheet 20, the light L13 and L14 irradiated from the LEDs 10 become diffused light L15 and L16 after passing through the light diffusion resin sheet 20. Since the light diffusion resin sheet 20 has the function of absorbing part of the light from the LEDs 10, the diffused lights L15 and L16 are weaker than the lights L13 and L14 emitted from the LEDs 10.

[0017] The concealing layer 40 is provided on the light-diffusing resin sheet 20. The concealing layer 40 serves to shield the LEDs 10 by blocking a portion of the light emitted from the LEDs 10. To this end, the concealing layer 40 blocks the diffused light L16 (first light). The concealing layer 40 also has a pattern portion DP through which the diffused light L15 from the LEDs 10 that has passed through the light-diffusing resin sheet 20 passes. In other words, the diffused light L15 shown in FIG. 3 is the second light that passes through the pattern portion DP. In this embodiment, the pattern portion DP has the shapes of icons 7 and letters. These icons 7 and letters are the first pattern displayed by the pattern portion DP. The concealing layer 40 is a layer that is highly opaque to visible light and appears black or gray, for example. If the concealing layer 40 is close to black, it is difficult to distinguish visually, so it may have a hue. The color of the concealing layer 40 will be described in detail later. By blocking the diffused light L16 by the concealing layer 40 and by allowing the diffused light L15 to pass through the pattern portion DP, the display panel device 5 can display the icons 7 and characters formed in the pattern portion DP by turning on the LED 10. The interference pigment layer 50 is provided on the light diffusion resin sheet 20. The interference pigment layer 50 displays a wood grain pattern 8, which is a second design drawn with an interference pigment, by reflected light L24 of incident light L23 entering from outside the display panel device 5. The interference pigment layer 50 is disposed at a position where diffused light L15 from the LED 10 passes through the light diffusion resin sheet 20 and the design portion DP of the concealing layer 40. At the position where diffused light L15 from the LED 10 passes through, when the LED 10 is lit, the display of the icons 7 and characters displayed by the design portion DP becomes dominant, and when the LED 10 is turned off, the display of the wood grain pattern 8 drawn with the interference pigment becomes dominant.

[0018] However, even when the LEDs 10 are turned off, incident light L231 enters the display panel device 5 from outside through the pattern portion DP toward the interior of the display panel device 5. This incident light L231 is reflected by the light diffusion resin sheet 20, and reflected light L241 is emitted to the outside of the display panel device 5. If this reflected light L241 is strong, the icons 7 and characters (first pattern) may be visually recognized even when the LEDs 10 are turned off. If the icons 7 and the like are visible with the LEDs 10 turned off, the design quality of the wood grain pattern 8 (second pattern) will be reduced. To prevent such a reduction in design quality, the light diffusion resin sheet 20 has the function of partially absorbing the light from the light source (LEDs 10). This function of the light diffusion resin sheet 20 to partially absorb the light from the light source functions to absorb part of the incident light L231 and weaken the reflected light L241. By weakening the reflected light L241, it is possible to solve the problem of visibility of the icons 7 and characters when the LED 10 is turned off. It is also conceivable that light may leak into the display panel device 5 from a light source other than the LEDs 10. Even if such light leakage occurs, if the leaked light is sufficiently weaker than the light emitted by the LEDs 10, the light absorbing effect of the light diffusion resin sheet 20 can prevent problems with visibility of the icons 7 and characters when the LEDs 10 are turned off.

[0019] (3) Light-diffusing resin sheet The light-diffusing resin sheet 20 also serves to support the concealing layer 40 and the interference pigment layer 50. The thickness of the light-diffusing resin sheet 20 is, for example, 0.1 mm to 5 mm. For example, as shown in FIG. 1 , when the light-diffusing resin sheet 20 is to be part of a dashboard 3, the shape of the light-diffusing resin sheet 20 must also match the shape of the dashboard 3. To facilitate the shape of the light-diffusing resin sheet 20 to match a predetermined shape, it is preferable to use a thermoplastic resin as the base resin of the light-diffusing resin sheet 20. Examples of thermoplastic resins used for the light-diffusing resin sheet 20 include polyester resin, polyethylene terephthalate (PET) resin, acrylic resin, polycarbonate resin, polybutylene terephthalate (PBT) resin, triacetyl cellulose resin, styrene resin, and ABS resin. However, other resins, such as UV-curable resins, ionizing radiation-curable resins, and thermosetting resins, may also be used for the light-diffusing resin sheet 20. Examples of UV-curable resins include epoxy acrylate, polyester acrylate, and urethane acrylate. Thermosetting resins include, for example, epoxy resin, acrylic resin, and polyurethane resin. The light-diffusing resin sheet 20 may also be a composite sheet made by stacking different types of resin sheets.

[0020] To achieve the light diffusion function, the light diffusion resin sheet 20 may have, for example, a light-diffusing additive or fine particles mixed into the resin, or may have minute irregularities or scratches on the surface. To achieve the function of partially absorbing light from the light source, the light diffusion resin sheet 20 may have, for example, a colorant or a light-absorbing agent added thereto. The added colorant may be, for example, a black or gray colorant. 4 shows the display when the LEDs 10, 110 are turned on and off in the cases of no light diffusion, when a white diffusion plate 120 is used, and when a smoke-colored light diffusion resin sheet 20 is used. The configuration of a display panel device 300 without light diffusion is shown in FIG. 7. The configuration of a display panel device 300 without light diffusion is the same as the configuration of the display panel device 100 shown in FIG. 9 except that the white diffusion plate 120 is removed. 4, when the light source is ON (LEDs 10 and 110 are lit), it can be seen that the display of display panel devices 5 and 100, which perform light diffusion, has uniform brightness and improved contrast compared to the display of display panel device 300. Also, in FIG. 4, when the light source is OFF (LEDs 10 and 110 are lit), it can be seen that the display of display panel device 5 does not have the problem of icons and characters being visible within the wood grain pattern compared to the display of display panel device 100.

[0021] FIG. 5 shows the appearances of a blank (a transparent acrylic plate having a concealing layer 40 and an interference pigment layer 50 formed thereon) and samples A1 to A3 (a light-diffusing resin sheet 20 having a concealing layer 40 and an interference pigment layer 50 formed thereon) placed on a white sheet. In the blank, the icons and letters are clearly visible within the wood grain pattern. In sample A1, the icons and letters are less visible than in the blank. In samples A2 and A3, the icons and letters are no longer visible. In samples A1, A2, and A3, the thickness of the light-diffusing resin sheet 20 was varied to 1 mm, 2 mm, and 3 mm. The total light transmittance values ​​shown herein were measured in accordance with JIS K 7361-1. The haze values ​​shown herein were measured in accordance with JIS K 7136. For sample A1, the total light transmittance of a 1 mm thick light-diffusing resin sheet 20 is 34.5% and the haze is 22.8%, and when an interference pigment layer 50 is formed on a 1 mm thick light-diffusing resin sheet 20, the total light transmittance is 9.17% and the haze is 62.2%. For sample A2, the total light transmittance of a 2 mm thick light-diffusing resin sheet 20 is 13.3% and the haze is 36.9%, and when an interference pigment layer 50 is formed on a 2 mm thick light-diffusing resin sheet 20, the total light transmittance is 3.55% and the haze is 68.7%. For sample A3, the total light transmittance of a 3 mm thick light-diffusing resin sheet 20 is 5.37% and the haze is 47.7%, and when an interference pigment layer 50 is formed on a 3 mm thick light-diffusing resin sheet 20, the total light transmittance is 1.41% and the haze is 73.8%.

[0022] 6 shows the appearance of samples B1 to B3 (samples B1 to B3) in which a light-diffusing resin sheet 20 having a concealing layer 40 and an interference pigment layer 50 formed thereon is placed on a white sheet. In samples B1 to B3, the icons and characters are no longer visible. In samples B1, B2, and B3, the thickness of the light-diffusing resin sheet 20 is the same at 2 mm, and the total light transmittance is varied. For sample B1, the light-diffusing resin sheet 20 has a total light transmittance of 25.2% and a haze of 99.3%, and when an interference pigment layer 50 is formed on the light-diffusing resin sheet 20, the total light transmittance is 6.6% and the haze is 98.8%. For sample B2, the light-diffusing resin sheet 20 has a total light transmittance of 1.42% and a haze of 98.8%, and when an interference pigment layer 50 is formed on the light-diffusing resin sheet 20, the total light transmittance is 0.35% and the haze is 100%. For sample B3, the light-diffusing resin sheet 20 has a total light transmittance of 8.1% and a haze of 98.9%, and when an interference pigment layer 50 is formed on the light-diffusing resin sheet 20, the total light transmittance is 2.05% and the haze is 98.5%.

[0023] The above are only a portion of the experimental results, and the preferred ranges for total light transmittance and haze were identified from the experimental results. In order to significantly improve the concealing property of the pattern portion DP, it is preferable that the total light transmittance of the light-diffusing resin sheet 20 is 30% or less and 1% or more. In order to obtain sufficient brightness to display the design portion DP when the light source is turned on, it is preferable that the light diffusion resin sheet 20 has a total light transmittance of 5% or more. In order to ensure sufficiently uniform brightness in the display of the pattern portion EP when the LED 10 (light source) is turned on and to improve the contrast between the pattern portion DP and the portion other than the pattern portion DP, it is preferable that the haze of the light-diffusing resin sheet 20 is configured to be 30% or more and 100% or less.

[0024] (4) Hiding layer The concealing layer 40 is a layer having a total light transmittance of 0.2% or less in areas other than the design portion DP. The concealing layer 40 is formed, for example, by printing ink in which a black absorbing pigment is dispersed in resin. The design portion DP for representing the icons 7 and letters is, for example, an area that is not printed with ink. The color of the concealing layer 40 is set by the SCE method so that the L value, a value, and b value are equal to or smaller than the absolute values ​​of those of the light diffusion resin sheet 20. For example, the L value of the light diffusion resin sheet 20 is set to 10, the a value to 2, and the b value to -2, while the L value of the concealing layer 40 is set to 3, the a value to 1, and the b value to 1. The color of the concealing layer 40 is set, for example, by the SCE method so that the L value is equal to or greater than 0 and equal to 30, the a value is in the range of -5 to +5, and the b value is in the range of -5 to +5. To make it easier to set the color of the interference pigment, it is preferable that the color of the concealing layer 40 be set, for example, using the SCE method, with an L value of 0 or more and 3 or less, an a value in the range of -1 to +1, and a value in the range of -1 to +1. (5) Interference pigment layer The interference pigment layer 50 can be formed, for example, by printing using ink in which interference pigment particles are dispersed in a resin binder. An example of the interference pigment is the interference pigment 200 shown in FIG. 10. The thickness of the interference pigment layer 50 is set to an appropriate value, for example, within a range of 1 μm to 50 μm. The interference pigment layer 50 is formed on the light-diffusing resin sheet 20 on which the hiding layer 40 has been formed, by, for example, screen printing, offset printing, flexographic printing, gravure printing, or digital printing using inkjet or toner. The resin binder in which the interference pigment is dispersed is primarily composed of, for example, vinyl chloride acetate copolymer resin, acrylic resin, thermoplastic urethane resin, or polyester resin.

[0025] (6) Variations (6-1) Variation A In the above embodiment, the display panel device 5 includes only the LEDs 10, the light-diffusing resin sheet 20, the concealing layer 40, and the interference pigment layer 50. However, the display panel device 5 may include components other than the LEDs 10, the light-diffusing resin sheet 20, the concealing layer 40, and the interference pigment layer 50. The display panel device 5 may include, for example, a protective layer that covers the interference pigment layer 50 and transmits visible light. The protective layer may be, for example, a layer that is harder than the interference pigment layer 50. The display panel device 5 may include, for example, a transparent surface layer that covers the interference pigment layer 50 and provides an uneven surface. For example, by providing the unevenness of the surface layer with a wood-like texture, not only can the wood grain pattern visually resemble actual wood, but the unevenness can also tactilely resemble actual wood. (6-2) Variation B In the above embodiment, the housing of the display panel device 5 is omitted, but the display panel device 5 may also include a housing. (6-3) Variation C The display panel device 5 shown in FIG. 3 may further include a metallic layer 90 (shown in FIG. 8) on the rear surface 50b of the interference pigment layer 50. The metallic layer 90 reflects a relatively large amount of incident light L23 incident from the front surface 50a of the interference pigment layer 50 and transmits a portion of light L13 incident from the rear surface 50b of the interference pigment layer 50. The thickness of the metallic layer 90 is, for example, 0.5 μm to 5 μm. The metallic layer 90 contains, for example, an absorbing pigment that absorbs less light than the absorbing pigment in the hiding layer 40. The metallic layer 90 is formed, for example, by printing ink in which metal powder is uniformly dispersed in a transparent binder resin. By providing the metallic layer 90, more light is reflected from the front surface 50a of the interference pigment layer 50 than when the metallic layer 90 is not provided, making the pattern on the interference pigment layer 50 appear brighter. In other words, providing the metallic layer 90 increases the brightness of the pattern. When the metallic layer 90 is provided, it is preferable to adjust the color of the transmitted light (here, the color of the icon 7) after the light L13 has passed through the metallic layer 90 as well.

[0026] (7) Features (7-1) In the display panel device 5 of the above embodiment, the light diffusion resin sheet 20 is disposed at a position where it is irradiated with light from the LEDs 10, which are light sources. The concealing layer 40 and the interference pigment layer 50 are provided on the light diffusion resin sheet 20. The concealing layer 40 blocks the first light of the LEDs 10 (diffused light L16 in FIG. 3 ) to hide the LEDs 10. In other words, the concealing layer 40 prevents the LEDs 10 from being visible from outside the display panel device 5. The concealing layer 40 has a pattern portion DP. The pattern portion DP is a portion that transmits the second light of the LEDs 10 (diffused light L15 in FIG. 3 ) that has passed through the light diffusion resin sheet 20. This diffused light L15 displays the icon 7, which is the first pattern, and the letters "PASSENGER AIR BAG," "ON," and "OFF." The interference pigment layer 50 displays a wood grain pattern 8, which is a second pattern different from the first pattern drawn by the interference pigment, by reflected light L24 (see FIG. 3) of light incident from outside the display panel device 5. The interference pigment layer 50 is disposed at a position where diffused light L15 from the LEDs 10 passes through the light diffusion resin sheet 20 and the pattern portion DP of the concealing layer 40. In other words, there is a portion where the pattern portion DP (such as the icon 7, which is the first pattern) and the wood grain pattern 8, which is the second pattern, overlap. The display panel device 5 configured in this manner has the function of diffusing light L13, L14 (see FIG. 3) emitted from the LEDs 10 by the light diffusion resin sheet 20, while improving the concealment of the pattern portion DP displayed when the LEDs 10 are lit. Furthermore, by using the light diffusion resin sheet 20, the white diffusion plate 120 can be omitted. Furthermore, since the display panel device 5 can be assembled using a single light diffusion resin sheet 20 instead of the transparent resin sheet 130 and diffusion plate 120 in FIG. 9, the manufacturing cost of the display panel device 5 can be reduced compared to the display panel device 100.

[0027] (7-2) By configuring the light-diffusing resin sheet 20 so that the total light transmittance is 1% or more and 30% or less, the concealment of the pattern portion DP can be improved. This can be seen, for example, from the fact that the pattern portion DP is slightly visible in sample A1 (total light transmittance 34.5%) shown in Figure 5, whereas the pattern portion DP is almost invisible in sample A2 (total light transmittance 13.3%). (7-3) By configuring the light diffusion resin sheet 20 so that the total light transmittance is 5% or more, it becomes easier to obtain sufficient brightness for displaying the design portion DP when the LED 10 is turned on. (7-4) By configuring the light diffusion resin sheet 20 so that the haze is between 30% and 100%, it is possible to make the brightness of the displayed pattern portion DP sufficiently uniform when the LED 10 is turned on, and to improve the contrast between the pattern portion DP and the portion other than the pattern portion DP. Compared to the case without light diffusion shown in Figure 4 when the light source is ON, when a white diffusion plate 120 and a smoke-colored light diffusion resin sheet 20 are used, it is believed that the improvement in brightness uniformity and contrast can be understood.

[0028] (7-5) The color of the light-diffusing resin sheet 20 is configured in the SCE method so that the L value is between 0 and 30, the a value is in the range of -5 to +5, and the b value is in the range of -5 to +5. As a result, the hue does not change in the light-diffusing resin sheet, and the pattern portion DP can be displayed using the light source color. (7-6) As explained in the embodiment, when the light diffusing resin sheet 20 is configured to be based on polycarbonate resin, it can have a strength sufficient to be used in an instrument panel 1 of an automobile. Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible within the scope of the gist of the invention. In particular, the multiple embodiments and modifications described in this specification can be arbitrarily combined as necessary. [Explanation of symbols]

[0029] 1. Instrument panel 5. Display panel device 7 Icon (Example of the first design) 8 Wood grain pattern (example of second design) 10 LED (example of light source) 20 Light diffusion resin sheet 40 Hidden Layer 50 interference pigment layer

Claims

1. A light source and a translucent light-diffusing resin sheet disposed at a position where the light from the light source is irradiated and having a function of absorbing part of the light from the light source and a function of diffusing the light; A concealing layer provided on the light diffusion resin sheet, which blocks the first light of the light source to hide the light source and has a pattern portion for transmitting the second light of the light source transmitted through the light diffusion resin sheet to display a first pattern; an interference pigment layer provided on the light-diffusing resin sheet, which displays a second pattern different from the first pattern drawn by an interference pigment by reflected light of light incident from outside the device; Equipped with The interference pigment layer is disposed at a position through which the first light that has passed through the light-diffusing resin sheet and the pattern portion of the concealing layer passes.

2. The light-diffusing resin sheet has a total light transmittance (measured in accordance with JIS K7361-1) of 1% or more and 30% or less. The display panel device according to claim 1 .

3. The light-diffusing resin sheet has a total light transmittance of 5% or more. The display panel device according to claim 2 .

4. The light-diffusing resin sheet has a haze (measured in accordance with JIS K7136) of 30% or more and 100% or less. The display panel device according to claim 1 .

5. The color of the light-diffusing resin sheet (measured in accordance with JIS Z8722) is set so that the L value is 0 or more and 30 or less, the a value is in the range of −5 to +5, and the b value is in the range of −5 to +5. The display panel device according to claim 1 .

6. The light-diffusing resin sheet is based on a polycarbonate resin. The display panel device according to claim 1 .

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