Display panel device

Abstract

[Problem] To allow a display panel device that comprises an interference pigment layer to diffuse light that is irradiated from a light source and also improve the concealment properties of a pattern part that is displayed by lighting of the light source at low cost. [Solution] A concealment layer (40) has a pattern part (DP) that is for blocking first light (diffused light L(16)) from a light source that is an LED (10) to conceal the LED (10) and also for transmitting second light (diffused light L(15)) from the LED (10) that has passed through a light-diffusing resin sheet (20) to display a first pattern. An interference pigment layer (50) displays a second pattern that is different from the first pattern and is rendered by an interference pigment by means of reflected light L(24) of light (incident light L(23)) that arrives from the outside. The interference pigment layer (50) is provided at a position through which light from the LED (10) that has passed through the light-diffusing resin sheet (20) and the pattern part (DP) of the concealment layer (40) passes.

Description

Display panel device

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

[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 LEDs (Light Emitting Diodes) and the panel unit. The LEDs in Patent Document 1 are a type of light source. The provision of the white diffusion sheet contributes to uniforming the LED light that passes through the panel unit, helping to make the display appear more beautiful. The diffusion sheet also serves to prevent the internal structure of the LEDs and other components from being seen through the panel unit.

[0003] Japanese Patent Application Laid-Open No. 2022-28602

[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 prototyped a display panel device 100 equipped with a white diffuser plate 120 that diffuses light emitted from the LEDs 110. In the display panel device 100 shown in FIG. 9 , the diffused light L11 emitted from the LEDs 110 and diffused by the diffuser plate 120 passes through a transparent resin sheet 130 and then through the pattern portion DP. The diffused light L12 emitted from the LEDs 110 and diffused by the diffuser plate 120 is blocked by a concealing layer 140. The concealing layer 140 is, for example, black or a grayish-black color. By blocking the diffused light L12 by the concealing layer 140 and by the diffused light L11 passing 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 of a device in which a specific icon is formed as a design on the design 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 an interference pigment on the interference pigment layer 150. For ease of understanding, a wood grain pattern drawn with an interference pigment will be described here. 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. The interference pigment used in the interference pigment layer 150 will now be further described with reference to FIG. 10 .

[0006] FIG. 10 schematically shows 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 shows a state in which incident light L211 and L212 are incident on the shell portion 202 of the interference pigment 200. Reflected light L221 is light that is the incident light L211 reflected by the surface of the shell portion 202. Reflected light L222 is light that is the incident light L212 that travels through the shell portion 202 and is reflected by the core portion 201. 9. The reflected light beams L221 and L222 interfere with each other constructively, and the interfering light beams of a particular wavelength become stronger, resulting in color development. 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, a blue interference pigment can be obtained by adjusting the thickness of the shell portion 202 so that the wavelengths intensified by interference are blue wavelengths. Visible light irradiated from a light source (e.g., LED 110) also enters the interference pigment 200. For example, the diffused light L11 incident on the interference pigment 200 in FIG. 10 is visible light irradiated from the light source. The diffused light L11 enters the interference pigment 200, passes through the interference pigment 200, and exits the interference pigment 200 in the opposite direction. This diffused light L11 transmitted through the interference pigment 200 is the light transmitted 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 characteristics described above, among the incident light L21 incident on the interference pigment layer 150 from outside the device, there is incident light L213 that passes through the pattern portion DP and reaches the diffuser plate 120. Because of the presence of 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 Figure 9, the base color of the interference pigment 200 is black (the hiding layer 140), so the color of the interference pigment 200 is weakened in the pattern portion DP where the diffuser plate 120 is present. In other words, the inventors of the present application discovered a problem through prototype production of the display panel device 100 that, in a display panel device 100 having an interference pigment layer 150, the use of the diffuser plate 120 induces visibility of the pattern portion DP even when the LEDs 110 are 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 the pattern portion DP being visible when the LED 110 is not lit. However, if an absorbing pigment were 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 were 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, adding various layers or sheets to solve the problem of the pattern portion DP being visible when using such a diffusion plate 120 would result in an increase in the cost of the display panel device.

[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.

[0010] Several embodiments for solving the problems will be described below. These embodiments 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 light from the light source is irradiated. The concealing layer and the interference pigment layer are provided on the light-diffusing resin sheet. The concealing layer has a pattern portion for blocking a first light from the light source to conceal the light source, and for transmitting a second light from the light source that has passed through the light-diffusing resin sheet to display a first pattern. The interference pigment layer displays a second pattern, which 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 aspect, 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 portion 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 to have 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 the second embodiment achieves favorable concealment of the patterned portion. A display panel device according to a third embodiment is the display panel device according to the second embodiment, wherein the light-diffusing resin sheet is configured to have a total light transmittance of 5% or more. The display panel device according to the third embodiment makes it easier to obtain sufficient brightness for displaying the patterned portion when the light source is turned on. A display panel device according to a fourth embodiment is the display panel device according to any one of the first to third embodiments, wherein the light-diffusing resin sheet is configured to have a haze (measured in accordance with JIS K7136) of 30% or more and 100% or less. The display panel device according to the fourth embodiment can achieve sufficiently uniform brightness in the display of the patterned portion when the light source is turned on, thereby improving the contrast between the patterned portion and portions other than the patterned portion.

[0012] A display panel device according to a fifth aspect is any of the display panel devices according to 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 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. According to the display panel device of the fifth aspect, the hue does not change due to the light-diffusing resin sheet, so the pattern portion can be displayed using the light source color. A display panel device according to a sixth aspect is any of the display panel devices according to the first to fifth aspects, wherein the light-diffusing resin sheet is configured to be based on polycarbonate resin. The display panel device according to the sixth aspect is easily strong enough to be used, for example, in an automotive instrument panel. Note that being based on polycarbonate resin means that the resin contains 50% or more by weight of polycarbonate resin.

[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.

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

[0015] (1) Example of Use of Display Panel Device FIGS. 1 and 2 show an automobile instrument panel 1. 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 also 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, while 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 other characters on the dashboard 3, as shown in FIG. 1. When the LEDs 10 (see FIG. 3 ) are turned off, the display panel device 5 displays the wood grain pattern 8 on the dashboard 3 by the interference pigment layer 50 (see FIG. 3 ), as shown in FIG. 2 , but does not display the icons 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 impart sufficient strength to the display panel device 5 to prevent damage to the instrument panel 1 in the event of an accident, etc. In such cases, it is preferable to use a polycarbonate resin for the light diffusion resin sheet 20 (see FIG. 3 ), which will be described later.

[0016] (2) Configuration of the Display Panel Device As shown in FIG. 3 , the display panel device 5 includes an LED 10 as a light source, a light-diffusing resin sheet 20, a concealing layer 40, and an interference pigment layer 50. Here, an example using an LED 10 as a light source will be described, but the light source may be other than an LED. Examples of light sources that can be used include electroluminescence (EL), fluorescent lamps, and incandescent lamps. In the display panel device 5, the LED 10, the light-diffusing 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-diffusing resin plate" is a type of "light-diffusing resin sheet." The light-diffusing resin sheet 20 is positioned where light from the LED 10 is irradiated. Therefore, light L13 and L14 irradiated from the LED 10 enters the light-diffusing resin sheet 20. The light-diffusing resin sheet 20 has the function of partially absorbing and diffusing the light from the LED 10. Such a light-diffusing resin sheet 20 is translucent. The color of the light-diffusing resin sheet 20 is set, for example, in 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 Z8722. In other words, the light-diffusing resin sheet 20 exhibits a smoky color. Due to the light-diffusing function of the light-diffusing resin sheet 20, the light L13 and L14 emitted from the LED 10 becomes diffused light L15 and L16 after passing through the light-diffusing resin sheet 20. Because the light-diffusing resin sheet 20 has the function of partially absorbing the light from the LED 10, the diffused light L15 and L16 are weaker than the light L13 and L14 emitted from the LED 10.

[0017] The concealing layer 40 is provided on the light-diffusing resin sheet 20. The concealing layer 40 serves to shield a portion of the light emitted from the LEDs 10, thereby hiding the LEDs 10. To this end, the concealing layer 40 shields 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 an icon 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. Since the concealing layer 40 is difficult to distinguish visually when it is close to black, 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 using the diffused light L15 that passes through the pattern portion DP, the display panel device 5 can display the icons 7 and letters formed in the pattern portion DP by turning on the LEDs 10. The interference pigment layer 50 is provided on the light-diffusing resin sheet 20. The interference pigment layer 50 displays the wood grain pattern 8, which is the second pattern drawn with the interference pigment, using reflected light L24 of incident light L23 that enters from outside the display panel device 5. The interference pigment layer 50 is disposed at a position where the diffused light L15 from the LEDs 10 that has passed through the light-diffusing resin sheet 20 and the pattern portion DP of the concealing layer 40 passes through. At the position where the diffused light L15 from the LEDs 10 passes through, when the LEDs 10 are turned on, the display of the icons 7 and letters displayed by the pattern portion DP becomes dominant, and when the LEDs 10 are 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 exterior 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 other elements are visible with the LEDs 10 turned off, the design of the wood grain pattern 8 (second pattern) may be diminished. To prevent this degradation of design, 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 a portion 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 LEDs 10 are turned off. It is also possible that light leaks into the display panel device 5 from a light source other than the LEDs 10. Even if such light leakage occurs, as long as the leaked light is sufficiently weaker than the light emitted by the LEDs 10, the light absorption effect of the light diffusion resin sheet 20 can prevent the problem of visibility of the icons 7 and characters when the LEDs 10 are turned off.

[0019] (3) Light Diffusion Resin Sheet The light diffusion resin sheet 20 also serves to support the concealing layer 40 and the interference pigment layer 50. The thickness of the light diffusion resin sheet 20 is, for example, 0.1 mm to 5 mm. For example, as shown in FIG. 1 , when the light diffusion resin sheet 20 is to be part of a dashboard 3, the shape of the light diffusion resin sheet 20 must also match the shape of the dashboard 3. To facilitate the shape of the light diffusion resin sheet 20 to match a predetermined shape, it is preferable to use a thermoplastic resin as the base resin of the light diffusion resin sheet 20. Examples of thermoplastic resins that can be used for the light diffusion 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 diffusion resin sheet 20. Examples of UV-curable resins include epoxy acrylate, polyester acrylate, and urethane acrylate. Examples of thermosetting resins include 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 contain, for example, additives or fine particles with a light diffusion effect mixed into the resin, or may have fine irregularities or scratches on its surface. To partially absorb light from the light source, the light diffusion resin sheet 20 may contain, for example, a colorant or a light absorber. The colorant may be, for example, a black or gray colorant. FIG. 4 shows the display without light diffusion, with a white diffuser 120, and with a smoke-colored light diffusion resin sheet 20, with the LEDs 10 and 110 turned on and off. The configuration of a display panel device 300 without light diffusion is shown in FIG. 7. The configuration of the display panel device 300 without light diffusion is the same as the display panel device 100 shown in FIG. 9, except that the white diffuser 120 is removed. 4, when the light source is ON (LEDs 10 and 110 are lit), it can be seen that the display of the display panel devices 5 and 100, which use light diffusion, has uniform brightness and improved contrast compared to the display of the 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 the 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 the 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 (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, 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 is changed to 1 mm, 2 mm, and 3 mm. The total light transmittance values ​​shown in this specification are measured in accordance with JIS K7361-1. The haze values ​​shown in this specification are measured in accordance with JIS K7136. For sample A1, the total light transmittance of a 1 mm-thick light-diffusing resin sheet 20 was 34.5%, and the haze was 22.8%. When an interference pigment layer 50 was formed on the 1 mm-thick light-diffusing resin sheet 20, the total light transmittance was 9.17%, and the haze was 62.2%. For sample A2, the total light transmittance of a 2 mm-thick light-diffusing resin sheet 20 was 13.3%, and the haze was 36.9%. When an interference pigment layer 50 was formed on the 2 mm-thick light-diffusing resin sheet 20, the total light transmittance was 3.55%, and the haze was 68.7%. For sample A3, the total light transmittance of a 3 mm-thick light-diffusing resin sheet 20 was 5.37%, and the haze was 47.7%. When an interference pigment layer 50 was formed on the 3 mm-thick light-diffusing resin sheet 20, the total light transmittance was 1.41%, and the haze was 73.8%.

[0022] FIG. 6 shows the appearance of samples B1 to B3 (each of which has a light-diffusing resin sheet 20 with a concealing layer 40 and an interference pigment layer 50 formed thereon) placed on a white sheet. In samples B1 to B3, the icons and text are no longer visible. Samples B1, B2, and B3 have the same thickness of the light-diffusing resin sheet 20, 2 mm, but with different total light transmittances. For sample B1, the light-diffusing resin sheet 20 has a total light transmittance of 25.2% and a haze of 99.3%. When the 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%. When the 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 total light transmittance of the light-diffusing resin sheet 20 is 8.1% and the haze is 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 experimental results identified preferred ranges for total light transmittance and haze. To significantly improve the concealment of the pattern portion DP, the total light transmittance of the light-diffusing resin sheet 20 is preferably 1% or more and 30% or less. To obtain sufficient brightness for displaying the pattern portion DP when the light source is turned on, the total light transmittance of the light-diffusing resin sheet 20 is preferably 5% or more. To ensure sufficiently uniform brightness when displaying the pattern portion EP when the LED 10 (light source) is turned on and to improve the contrast between the pattern portion DP and portions other than the pattern portion DP, the light-diffusing resin sheet 20 is preferably configured so that its haze is 30% or more and 100% or less.

[0024] (4) Concealing Layer The concealing layer 40 is a layer with 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 characters is, for example, an area not printed with ink. The color of the concealing layer 40 is set using the SCE method such that the L value, a value, and b value are equal to or smaller than the absolute values ​​of those of the light-diffusing resin sheet 20. For example, the light-diffusing resin sheet 20 has an L value of 10, an a value of 2, and a b value of -2, while the concealing layer 40 has an L value of 3, an a value of 1, and a b value of 1. The color of the concealing layer 40 is set, for example, using the SCE method such that the L value is greater than or equal to 0 and less than 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 facilitate the color development of the interference pigment, the color of the hiding layer 40 is preferably set, for example, in the SCE system, with an L value of 0 to 3, an a value in the range of -1 to +1, and a b 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 an 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 thickness, for example, in the 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 composed, for example, of a vinyl chloride acetate copolymer resin, an acrylic resin, a thermoplastic urethane resin, or a polyester resin as its main material.

[0025] (6) Modifications (6-1) Modification 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 with a higher hardness 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 texture of wood with unevenness on the surface layer, not only can the wood grain pattern visually resemble actual wood, but the unevenness can also tactilely resemble actual wood. (6-2) Modification B In the above embodiment, the display panel device 5 does not include a housing or the like, 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, as 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 (diffused light L16 in FIG. 3 ) of the LEDs 10 to conceal the LEDs 10. In other words, the concealing layer 40 makes the LEDs 10 invisible 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 (diffused light L15 in FIG. 3 ) of the LEDs 10 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, a second design different from the first design depicted 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 positioned at a location where diffused light L15 from the LED 10 passes through the light-diffusing resin sheet 20 and the design portion DP of the concealing layer 40. In other words, there is a portion where the design portion DP (such as the icon 7, which is the first design) and the wood grain pattern 8, which is the second design, overlap. The display panel device 5 configured in this manner can improve the concealment of the design portion DP displayed when the LED 10 is lit, while providing the light-diffusing resin sheet 20 with the function of diffusing light L13 and L14 (see FIG. 3) emitted from the LED 10. Furthermore, by using the light-diffusing resin sheet 20, the white diffuser plate 120 can be omitted. Furthermore, since the display panel device 5 can be assembled using a single light-diffusing resin sheet 20 instead of the transparent resin sheet 130 and the diffusion plate 120 in Figure 9, the manufacturing costs 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 its total light transmittance is 30% or less and 1% or more, 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 FIG. 5, while the pattern portion DP is almost invisible in sample A2 (total light transmittance 13.3%). (7-3) By configuring the light-diffusing resin sheet 20 so that its total light transmittance is 5% or more, it becomes easier to obtain sufficient brightness for displaying the pattern portion DP when the LED 10 is turned on. (7-4) By configuring the light-diffusing resin sheet 20 so that its haze is 30% or more and 100% or less, it is possible to achieve sufficiently uniform brightness in the display of the pattern portion DP when the LED 10 is turned on, and to improve the contrast between the pattern portion DP and the portions other than the pattern portion DP. Compared to the case where there is no light diffusion as shown in Figure 4 when the light source is ON, when a white diffusion plate 120 is used and when a smoke-colored light diffusion resin sheet 20 is used, it is believed that the improvement in brightness uniformity and contrast can be seen.

[0028] (7-5) The color of the light-diffusing resin sheet 20 is configured in the SCE system 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. This prevents the hue from changing in the light-diffusing resin sheet, allowing the pattern portion DP to be displayed using the light source color. (7-6) As described in the embodiment, when the light-diffusing resin sheet 20 is configured to be based on polycarbonate resin, it can obtain a strength sufficient for use in an automotive instrument panel 1. While 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 invention. In particular, the multiple embodiments and modifications described in this specification can be arbitrarily combined as needed.

[0029] DESCRIPTION OF SYMBOLS 1 Instrument panel 5 Display panel device 7 Icon (example of first design) 8 Wood grain pattern (example of second design) 10 LED (example of light source) 20 Light diffusion resin sheet 40 Hiding layer 50 Interference pigment layer

Claims

1. A display panel device comprising: a light source; a translucent light-diffusing resin sheet that is placed at a position where light from the light source is irradiated and has the function of absorbing part of the light from the light source and diffusing light; a concealing layer that is placed on the light-diffusing resin sheet and has a pattern portion that blocks a first light from the light source to hide the light source and passes a second light from the light source that has passed through the light-diffusing resin sheet to display a first pattern; and an interference pigment layer that is placed on the light-diffusing resin sheet and displays a second pattern that is different from the first pattern drawn with an interference pigment by reflected light of light that is incident from outside the device, wherein the interference pigment layer is placed 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.

2. The display panel device according to claim 1, wherein 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.

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

4. The display panel device according to any one of claims 1 to 3, wherein the light-diffusing resin sheet has a haze (measured in accordance with JIS K7136) of 30% or more and 100% or less.

5. A display panel device described in any one of claims 1 to 3, wherein 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.

6. The display panel device according to any one of claims 1 to 3, wherein the light-diffusing resin sheet is based on polycarbonate resin.

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