Method for manufacturing resin component

Abstract

To provide a method for manufacturing a resin part having good appearance in a resin product different in thickness.SOLUTION: The method for manufacturing a resin component 20 is a method for manufacturing the resin component 20 including a plate-shaped part having a plate-shaped part 20a with a uniform thickness and a projecting part 20a provided in a projecting shape on the plate-shaped part 20b, wherein the plate-shaped part 20a and the projecting part 20b are resin-molded independently of each other.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a resin part. [Background technology]

[0002] Patent Document 1 discloses an emblem, which is an example of a resin part. According to Patent Document 1, a paint layer is formed by applying paint to a part of a transparent resin part. As a result, light that passes through the paint layer and light that does not pass through the paint layer can exhibit different colors. This allows the emblem to have a pattern that can be recognized by people around it through the emitted light.

[0003] Patent Document 2 also discloses an emblem, which is an example of a resin part. According to Patent Document 2, the transparent resin part is formed to include portions of different thicknesses. In Patent Document 2, the portions of different thicknesses in the resin part are formed to make the letters of the emblem appear three-dimensional. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-037811 [Patent Document 2] Japanese Patent Application Publication No. 2018-105741 Summary of the Invention [Problem to be solved by the invention]

[0005] However, forming portions of different thicknesses in a resin part can easily cause molding defects in the resin part, resulting in poor appearance.

[0006] An object of the present disclosure is to provide a method for manufacturing a resin part that has a good appearance when it comes to resin products with different thicknesses. [Means for solving the problem]

[0007] A method for manufacturing a resin product according to one aspect of the present disclosure is a method for manufacturing a resin part including a plate-like portion having a plate-like portion with a uniform thickness and a convex stripe portion provided in a convex shape on the plate-like portion, The plate-like portion and the protruding portion are each independently molded from resin.

[0008] A method for manufacturing a resin product according to another aspect of the present disclosure is a method for manufacturing a resin part including a plate-like portion having a plate-like portion and a convex stripe portion provided in a convex shape on the plate-like portion, The protruding portion and a first region of the plate-like portion including an interface with the protruding portion, and a second region of the plate-like portion having a uniform thickness are each independently molded from resin. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a front view of the emblem. [Figure 2] FIG. 2 is a cross-sectional view of the emblem taken along line II-II in FIG. [Figure 3] FIG. 3 illustrates the transmission spectrum characteristics of the resin forming the resin layer. [Figure 4] FIG. 4 is a cross-sectional view of the resin part according to the first embodiment. [Figure 5] FIG. 5 illustrates a die set in the plate-like portion manufacturing process. [Figure 6] FIG. 6 illustrates an example of a die set in the step of manufacturing the ridge portion. [Figure 7] FIG. 7 illustrates a resin part according to the second embodiment. [Figure 8] FIG. 8 illustrates a mold set in the first region manufacturing process. [Figure 9] FIG. 9 illustrates a mold set in the second region manufacturing process. [Figure 10] FIG. 10 shows an example of a resin part according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. For the sake of convenience, the dimensions of each component shown in the drawings may differ from the actual dimensions of each component.

[0011] In the accompanying drawings, arrow F indicates the forward direction of the illustrated structure. Arrow B indicates the rearward direction of the illustrated structure. Arrow U indicates the upward direction of the illustrated structure. Arrow D indicates the downward direction of the illustrated structure. Arrow R indicates the rightward direction of the illustrated structure. Arrow L indicates the leftward direction of the illustrated structure. These directional expressions are used for convenience of explanation and do not limit the posture or direction of the illustrated structure in actual use.

[0012] Additionally, the term "front-rear direction" used in this specification refers to a direction along the aforementioned front and rear directions. The term "up-down direction" used in this specification refers to a direction along the aforementioned upward and downward directions. The term "left-right direction" used in this specification refers to a direction along the aforementioned left and right directions.

[0013] (Basic configuration) 1 is a front view of an emblem 1. The emblem 1 is an example of a lamp. The emblem 1 may be mounted on a vehicle, for example. The emblem 1 mounted on a vehicle may be a member representing the name or mark of the vehicle manufacturer, the name of the vehicle, or the like.

[0014] As illustrated in FIG. 1, the emblem 1 includes a decorative surface 2 and a casing 3. The decorative surface 2 is a surface that glows when a light source (not shown) is turned on. The decorative surface 2 is configured to exhibit one or more colors when the light source is turned on. The emblem 1 is configured such that, when the light source is turned on, a color-producing region 2a of the decorative surface 2 emits visible light, and a non-color-producing region 2b of the decorative surface 2 does not emit visible light. On the other hand, the emblem 1 may be configured such that, when the light source is turned off, the decorative surface 2 is dark and does not exhibit a different color.

[0015] Fig. 2 is a cross-sectional view of the emblem 1 taken along line II-II in Fig. 1. As illustrated in Fig. 2, the emblem 1 includes a light guide 10 and a resin part 20. The light guide 10 and the resin part 20 are housed in a casing 3.

[0016] The light guide 10 is configured to be able to emit light toward the resin part 20. The light guide 10 is an example of a light source. As the light source, a light emitting element and a light emitting unit that irradiate a certain size area with light approximately uniformly, such as a surface-emitting LED, can be used. The resin part 20 is a member made of resin. The surface of the resin part forms a decorative surface 2. The resin part 20 is configured to exhibit a color when light incident from the light guide 10 passes through it.

[0017] As illustrated in FIG. 2, the resin part 20 has portions with different thicknesses. In the example of FIG. 2, a notch is formed on the back surface of the resin part 20, where a portion is cut out in the thickness direction. This notch forms thick and thin portions in the resin part 20. Here, the thickness of the thick portion 20A, which is the thicker portion of the resin part 20, is designated as t1. The thickness of the thin portion 20B, which is the thinner portion of the resin part 20, is designated as t2. In this embodiment, the thick portion 20A is configured to form a non-coloring region 2b. The thin portion 20B is configured to form a coloring region 2a. Note that the decorative surface 2, which is the surface of the resin part 20, does not have any irregularities, and the surface of the resin part 20 is flat.

[0018] The resin part 20 has a resin layer made of the same type of resin whose transmission spectrum characteristics change depending on the thickness. When light from the light guide 10, which is a light source, passes through the resin layer, the transmission spectrum of the light passing through the resin layer varies depending on the thickness of the resin layer. FIG. 2 illustrates a case where the entire resin part 20 is formed from the resin layer. However, it is also possible that only a portion of the resin part 20 is formed from the resin layer, and the remaining portion of the resin part 20 is formed from a resin whose transmission spectrum characteristics do not change depending on the thickness.

[0019] The resin having a transmission spectrum characteristic that changes depending on the thickness may be a known resin. One example of a resin having a transmission spectrum characteristic that changes depending on the thickness is a methacrylic resin composition containing carbon black and a plurality of dyes selected from red, yellow, green, blue, purple, etc. The dye may be, for example, an anthraquinone dye, a heterocyclic compound dye, or a perinone dye.

[0020] Another example of a resin whose transmission spectrum characteristics change depending on the thickness may be a resin containing polycarbonate, one or more vinyl compounds, and one or more pigments or dyes. Examples of pigments include organic pigments such as monoazo and condensed azo, anthraquinone, isoindolinone, heterocyclic, perinone, quinacridone, perylene, thioindigo, dioxazine, and phthalocyanine, as well as inorganic pigments such as titanium oxide, carbon black, titanium yellow, iron oxide, ultramarine, cobalt blue, calcined pigments, metallic pigments (e.g., aluminum particles), mica, and pearl pigments. Examples of dyes include organic dyes such as anthraquinone, heterocyclic, and perinone. The above pigments and dyes may be used in combination.

[0021] FIG. 3 illustrates the transmission spectrum characteristics of the resin forming the resin layer. In FIG. 3, the transmission spectrum characteristics at thickness t1 are shown by a dashed line. In FIG. 3, the transmission spectrum characteristics at thickness t2 are shown by a solid line. In FIG. 3, the transmission spectrum characteristics at thickness t3 are shown by a dashed line. Note that thickness t3 will be described later as a modified example. As illustrated in FIG. 3, the resin forming the resin layer as a whole transmits light with long wavelengths, and the transmittance tends to decrease as the wavelength becomes shorter. Furthermore, the thinner the resin forming the resin layer, the shorter the wavelength at which the transmittance begins to decrease.

[0022] When the thickness of the resin layer is t1 (dotted line in Figure 3), the resin layer transmits only light in the infrared region and does not transmit light in the visible region. Therefore, only light in the infrared region is transmitted through the thick portion 20A, and the non-coloring region 2b does not appear to emit light even when viewed from the front.

[0023] On the other hand, when the thickness of the resin layer is t2 (solid line in FIG. 3), the resin layer transmits not only light in the infrared region but also light with longer wavelengths in the visible region. Therefore, the light that transmits through thin portion 20B is light in the infrared region and red light, so color-producing region 2a appears to emit red light when viewed from the front.

[0024] In a lighting fixture that partially irradiates visible light, as in Patent Document 1, a transparent coating is sometimes applied to the transparent portions and a non-transparent coating is sometimes applied to the non-transparent portions. However, in the manufacturing of lighting fixtures, the coating process is a factor that increases costs and man-hours.

[0025] When the light guide 10 is turned off, the portions of the resin layer with different thicknesses may be dark and not necessarily emit different colors. For example, a resin whose transmission spectrum characteristics change depending on the thickness may contain not only carbon black as a dye but also multiple types of dyes with complementary colors. As a result, when the light guide 10 is turned off, the decorative surface 2, whether in the colored region 2a or the non-colored region 2b, appears dark and monochromatic when viewed from the front.

[0026] On the other hand, when the light guide 10 is lit, the color-producing region 2a appears red.

[0027] According to the above configuration, when the light guide is turned off, the emblem 1 appears to be a single dark color. Therefore, when there is no need for display using the emblem 1, the emblem 1 is less noticeable, but when there is a need for display using the emblem 1, the emblem 1 becomes more noticeable because it is colored red. This makes it possible to create an emblem 1 that is easily noticeable.

[0028] Furthermore, in the emblem 1 having the above-described configuration, the resin layer is formed by resin molding, and therefore is easy to manufacture.

[0029] In the above example, the portion of the resin layer with a thickness of t1 emits red light, while the portion of the resin layer with a thickness of t2 does not emit light. However, the present invention is not limited to this. Because the resin layer is made of a resin whose transmission spectrum characteristics change depending on the thickness, the resin layer may be configured to have multiple types of portions with different thicknesses, thereby realizing an emblem that emits light in multiple colors. For example, the resin layer may be configured to include a portion whose thickness is adjusted to transmit red light, a portion whose thickness is adjusted to transmit green light, and a portion whose thickness is adjusted to transmit blue light. This eliminates the need for additional decoration such as painting, making it possible to realize an emblem 1 that emits light in multiple colors at low cost and with few steps.

[0030] (First embodiment) Next, a resin part 20 according to a first embodiment and a method for manufacturing the same will be described. Fig. 4 is a cross-sectional view of the resin part 20 according to the first embodiment. The resin part 20 according to the first embodiment is entirely made of a resin whose transmission spectrum characteristics vary depending on the thickness.

[0031] As shown in FIG. 4, when the resin part 20 is cut into regions, the resin part 20 can be expressed as having a plate-shaped portion 20a and a convex portion 20b. The plate-shaped portion 20a is a portion with a uniform thickness. The convex portion 20b is a portion provided in a convex shape on the plate-shaped portion 20a. The front surface of the plate-shaped portion 20a becomes the decorative surface 2, and the convex portion 20b is provided on the back surface of the plate-shaped portion 20a. The thickness of the resin part including the plate-shaped portion 20a and the convex portion 20b is defined as t1, and the thickness of only the plate-shaped portion 20a is defined as t2.

[0032] The plate-like portion 20a and the protruding portion 20b are each molded from resin independently. That is, the manufacturing method of the resin part 20 includes a plate-like portion manufacturing process and a protruding portion manufacturing process. Here, resin molding refers to a molding method such as extrusion molding, injection molding, insert molding, or mold molding in which molten resin is filled into a mold to obtain a component of a desired shape.

[0033] Fig. 5 illustrates a mold set in the plate-like portion manufacturing process. In Fig. 5, the resin part 20 to be manufactured is shown upside down compared to the resin part 20 illustrated in Fig. 4. As illustrated in Fig. 5, the mold set used in the plate-like portion manufacturing process includes a first cavity mold 111 and a second cavity mold 112.

[0034] The first cavity mold 111 and the second cavity mold 112 are configured to define a plate-shaped portion cavity C1 when closed. The plate-shaped portion cavity C1 is a space formed to have a width t2 in the thickness direction of the resin part 20. The first cavity mold 111 is a mold that opens upward and has a bottom surface and side surfaces that define the plate-shaped portion cavity C1. The second cavity mold 112 has an upper surface that defines the plate-shaped portion cavity C1. The first cavity mold 111 and the second cavity mold 112 are cooled by flowing a refrigerant such as water inside each of them.

[0035] An injection part (not shown) is formed in either the first cavity mold 111 or the second cavity mold 112. The injection part is a gate for pouring molten resin into the cavity. With the first cavity mold 111 and the second cavity mold 112 closed, the molten resin flows into the plate-like portion cavity C1 and solidifies, thereby forming the plate-like portion 20a.

[0036] Fig. 6 illustrates a mold set in the ridge portion manufacturing process. In Fig. 6, the resin part 20 to be manufactured is shown upside down compared to the resin part 20 illustrated in Fig. 4.

[0037] As illustrated in Fig. 6, the mold set used in the convex streak portion manufacturing process includes a first cavity mold 111 and a third cavity mold 113. As illustrated in Fig. 6, the convex streak portion manufacturing process is performed in a state where the plate-like portion 20a is accommodated in the first cavity mold 111.

[0038] The third cavity mold 113 is configured to define the convex streak portion cavity C2 together with the plate-like portion 20a housed in the first cavity mold 111. The third cavity mold 113 has a convex portion 113a that protrudes toward the inner surface of the cavity in the thickness direction of the resin part 20 by the difference in thickness (t1-t2) between the thick portion 20A and the thin portion 20B. The tip surface of the convex portion 113a abuts against the plate-like portion 20a. As a result, the convex streak portion cavity C2 is formed as a space with a width of t2 in the thickness direction of the resin part 20.

[0039] The third cavity mold 113 is cooled by flowing a coolant such as water inside it. An injection portion (not shown) is formed in the third cavity mold 113. With the first cavity mold 111 and the third cavity mold 113 closed, molten resin flows into the protruding portion cavity C2 and solidifies, thereby forming the protruding portion 20b. The protruding portion 20b is fixed to the plate-like portion 20a, thereby forming the resin part 20.

[0040] The resin part 20 has a different thickness depending on the part because the ridge portions 20b are formed. When such a resin part 20 is integrally molded, molding defects are likely to occur due to the resin molding. When molding defects occur, irregularities may be formed on the decorative surface 2 of the resin part 20. In particular, when the thickness does not change continuously, as in the case of the resin part 20, and there are portions where the thickness changes discontinuously due to steps or the like, molding defects are likely to occur significantly.

[0041] For example, sink marks, a type of molding defect, occur when the amount of thermal shrinkage of the resin differs due to the existence of areas with different thicknesses during resin molding, while welds, another type of molding defect, are caused in part by differences in the flow speed of the molten resin due to differences in the width of the cavity that serves as the flow path for the molten resin.

[0042] According to the manufacturing method of the resin part 20 of this embodiment, the plate-like portion 20a and the ridge portion 20b are each independently molded from resin. Therefore, even in a resin part 20 having a mixture of thicknesses t1 and t2 as shown in FIGS. 2 and 4, the plate-like portion 20a having a constant thickness t1 and the ridge portion 20b having a constant thickness t1-t2 are molded separately from each other, which reduces the occurrence of sink marks and welds due to the presence of portions with different thicknesses. This allows the resin part 20 with different thicknesses to be manufactured with a good appearance. The plate-like portion 20a and the ridge portion 20b may be formed from the same resin.

[0043] Unlike the present embodiment, emblems with specific patterns are typically created by combining a colored, transparent clear material with a light-blocking resin or by painting. However, the emblem 1 of the present embodiment employs a technique of varying thickness to differentiate between luminous and non-luminous states. Therefore, if the decorative surface 2 of the emblem 1 of the present embodiment is formed as a flat surface without discontinuities due to the interface between different resins or paint, the emblem 1 of the present embodiment can create the illusion that the pattern is not visible on its surface. This is expected to give the emblem 1 of the present embodiment a novel appearance. In this case, a more attractive appearance can be achieved by forming the decorative surface 2 as a flat surface without sink marks, welds, or the like, using the manufacturing method described with reference to Figures 5 and 6.

[0044] Second Embodiment Next, a resin part 120 according to a second embodiment and a method for manufacturing the same will be described. Fig. 7 illustrates a resin part 120 according to the second embodiment. As illustrated in Fig. 7, like the resin part 20 according to the first embodiment, the resin part 120 also includes a plate-like portion 120a and a protruding portion 120b. In Fig. 7, the interface IF between the plate-like portion 120a and the protruding portion 120b is virtually indicated by a dashed line.

[0045] The resin part 120 has a first region S1 and a second region S2. The first region S1 is a region including an interface IF between the protruding portion 120b and the plate-like portion 120a. The second region S2 is a region of the remaining plate-like portion 120a with a uniform thickness.

[0046] As with the resin part 20 of the first embodiment, the thickness of the resin part 120 including the plate-like portion 120a and the ridge portion 120b is defined as t1, and the thickness of only the plate-like portion 120a is defined as t2. The thickness of the second region is defined as T1. The first region S1 has a portion with a thickness T2 obtained by subtracting T1 from t1, and a portion with a thickness T3 obtained by subtracting T1 from t2. The thickness T2 is smaller than the thickness t1 and larger than the thickness t2 (t2 <T2<t1)。

[0047] In the second embodiment, the first region S1 and the second region S2 are each independently molded from resin, that is, the method for manufacturing the resin part 120 includes a first region manufacturing step and a second region manufacturing step.

[0048] 8 illustrates a mold set in the first region manufacturing process. As illustrated in FIG. 8, the mold set in the first region manufacturing process has a fourth cavity mold 114 and a fifth cavity mold 115.

[0049] The fourth cavity mold 114 and the fifth cavity mold 115 are configured to define a first region cavity C3 when closed. The fourth cavity mold 114 is an upwardly opening mold having a lower surface and side surfaces that define the first region cavity C3. The fifth cavity mold 115 has an upper surface that defines the first region cavity C3. The first region cavity C3 includes a space formed to have a width T2 in the thickness direction of the resin part 120 and a space formed to have a width T3. The fourth cavity mold 114 and the fifth cavity mold 115 are cooled by flowing a refrigerant such as water inside them. The first region cavity C3 is an example of a first cavity.

[0050] An injection portion (not shown) is formed in either the fourth cavity mold 114 or the fifth cavity mold 115. With the fourth cavity mold 114 and the fifth cavity mold 115 closed, the molten first resin flows into the first region cavity C3 and solidifies, thereby forming the first region S1.

[0051] Fig. 9 illustrates a mold set in the second region manufacturing process. As illustrated in Fig. 9, the mold set in the second region manufacturing process includes a fourth cavity mold 114 and a sixth cavity mold 116. As illustrated in Fig. 9, the second region manufacturing process is performed in a state where the first region S1 is housed in the fourth cavity mold 114.

[0052] The sixth cavity mold 116 is configured to define a second region cavity C4 together with the first region S1 accommodated in the fourth cavity mold 114. The sixth cavity mold 116 is cooled by flowing a refrigerant such as water inside. An injection port (not shown) is formed in the sixth cavity mold 116. With the fourth cavity mold 114 and the sixth cavity mold 116 closed, the molten second resin flows into the second region cavity C4 and solidifies, thereby forming the second region S2. The second region cavity C4 is a space formed to have a width T1 in the thickness direction of the resin part 120. The resin part 120 is formed by fixing the second region S2 to the first region S1. The second region cavity C4 is an example of a second cavity.

[0053] The first region S1 includes a region where the ridge portion 120b is formed and a region where the ridge portion 120b is not formed, resulting in a region where the thickness varies discontinuously. Therefore, as illustrated in FIG. 7, molding defects DF may occur on the surface of the first region S1. However, since the second region S2 is resin-molded to have a uniform thickness, molding defects such as sink marks and welds are less likely to occur in the second region S2. Therefore, when the first region S1 is viewed through the second region S2, sink marks and welds that occur in the first region S1 are not noticeable. This allows the resin part 120, which has different thicknesses, to be manufactured with a good appearance.

[0054] Furthermore, as described above, the resin molding of the second region S2 is performed after the resin molding of the first region S1. Therefore, molding defects DF, such as sink marks and welds, that occur during resin molding of the first region S1 are likely to occur at the interface between the first region S1 and the second region S2. Therefore, even if a molding defect DF occurs, resin flows into the region of the molding defect DF during resin molding of the second region S2, resulting in the molding defect DF disappearing. Alternatively, even if resin does not flow into the region of the molding defect DF during resin molding of the second region S2, the molding defect DF occurs inside the resin part 120, making the molding defect DF less noticeable from the outside of the resin part 120. If the second region S2 is resin molded using an opaque resin, the molding defect DF can be made particularly inconspicuous.

[0055] As illustrated in Figures 8 and 9, the fourth cavity mold 114, which is an example of a first mold that defines the first region cavity C3 for forming the first region S1, is positioned so that the convex strip portion 120b is located below the plate-shaped portion 120a.

[0056] The resin part 20 has a plate-like portion 20a with a uniform thickness and a protruding ridge portion 20b provided on the plate-like portion 20a. Therefore, molding defects DF, such as sink marks and welds, occur in the upper part of the first region S1 during the manufacturing of the first region S1. A sixth cavity mold 116, which is a second mold that defines the second region cavity C4 together with the first region S1 to form the second region S2, is disposed above the first region S1. Because the second region S2 is manufactured above the first region S1, molding defects DF, such as sink marks and welds, that occur in the upper part of the first region S1 are less likely to occur on the surface of the resin part 120. This makes molding defects DF less noticeable in the appearance of the resin part 120.

[0057] The first resin forming the first region S1 and the second resin forming the second region are different resins, and the second resin is formed of a resin having a higher transparency than the first resin.

[0058] The second region S2 is formed from a resin with a higher transmittance than the resin forming the first region S1, and therefore the appearance of a product such as a lamp in which the resin part 120 is mounted is improved.

[0059] The first resin is a resin whose light spectrum characteristics change depending on its thickness, as described with reference to Fig. 3. The second resin is a resin whose light spectrum characteristics do not change depending on its thickness. The second resin can be made of a resin generally called a clear resin, such as a transparent acrylic resin.

[0060] The first region S1 is formed from a resin whose light spectrum characteristics change depending on the thickness, and the thickness differs between the region where the convex streak portion 120b is formed and the region where it is not. For this reason, light that passes through the first region S1 does not emit light when it passes through the convex streak portion 120b, but emits light when it does not pass through the convex streak portion 120b. As a result, even if the resin part 120 is not decorated by painting or the like, patterns and the like are displayed when light passes through the first region S1. The second region S2 is formed of a highly transmittance resin whose spectral characteristics do not change with thickness. Therefore, no matter where light passes through the second region S2, the light transmits through the second region S2 with the hue formed by the first region S1 intact. This makes it easy to design the resin part 120 so that it displays a desired hue.

[0061] The present disclosure has been described above based on the embodiments. The present embodiment is an example of the present disclosure, and is not limited to the above-described embodiment, and can be freely modified, improved, etc. as appropriate. In addition, the material, shape, dimensions, numerical values, form, number, placement location, etc. of each component in the above-described embodiment are arbitrary and not limited as long as the present disclosure can be achieved.

[0062] Fig. 10 illustrates a resin part 220 according to a modified example. Fig. 10 illustrates a case where the entire resin part 220 is formed from a resin layer made of the same type of resin, whose transmission spectrum characteristics change depending on the thickness. In the resin part 220 according to the modified example, portions of the resin layer with different thicknesses develop different colors.

[0063] The resin part 220 according to the modified example also has portions with different thicknesses. The resin part 220 has a first thin portion 220B1 and a second thin portion 220B2 that are thinner than the thick portion 220A. The second thin portion 220B2 is formed to be thinner than the first thin portion 220B1. Here, the thickness of the thick portion 220A, which is the thickest portion of the resin part 220, is defined as t1. In the resin part 220, the thickness of the first thin portion 220B1 is defined as t2. In the resin part 220, the thickness of the second thin portion 220B2 is defined as t3.

[0064] The transmission spectrum characteristics at thickness t3 are indicated by a dashed line. As illustrated in Figure 3, when the resin layer has a thickness of t1, the resin layer transmits only light in the infrared region and does not transmit light in the visible region.

[0065] When the resin layer has a thickness of t2, the resin layer transmits not only light in the infrared region but also light with longer wavelengths in the visible region, so the light that transmits through the first thin portion 220B1 is light in the infrared region and red light.

[0066] Therefore, as shown in FIG. 3, when the resin layer has a thickness of t3, the resin layer allows the transmission of light with shorter wavelengths than when the resin layer has a thickness of t2. The light that passes through second thin portion 220B2 is infrared light, red, and yellow light. Therefore, thick portion 220A does not emit light, first thin portion 220B1 emits red light, and second thin portion 220B2 emits orange light. Note that by adjusting the thickness as desired, emblem 1 can be colored in red, orange, yellow, green, blue-green, blue, purple, and other colors.

[0067] A lamp using such a resin part 220 can emit visible light of multiple hues without being painted with multiple paints.

[0068] The resin part 220 according to this modified example can also be manufactured by the manufacturing method described above with reference to FIGS. 5 and 6 or the manufacturing method described above with reference to FIGS. 8 and 9, the first region S1 is formed from a resin whose spectral characteristics change depending on its thickness, and the thickness differs between the region where the convex stripe portion 120b is formed and the region where it is not. Therefore, light passing through the first region S1 exhibits different hues depending on whether it passes through the convex stripe portion 120b or not. This allows a pattern or the like made up of multiple colors to be displayed even if the resin part 120 is not decorated, such as painted.

[0069] In the above-described embodiment, the entire resin part constitutes the decorative portion and the plate-shaped portion, but the present disclosure is not limited to this. In other words, the resin part may be configured to have a function other than decoration. For example, the resin part may include a portion that becomes part of the casing.

[0070] The configurations listed below also form part of this disclosure. (1): A method for manufacturing a resin part including a plate-like portion having a plate-like portion with a uniform thickness and a protruding portion provided in a protruding shape on the plate-like portion, A method for manufacturing a resin part, wherein the plate-like portion and the protruding portion are each independently molded from resin. (2): the plate-like portion and the protruding portion are formed of a resin whose light spectral characteristics change depending on the thickness; A method for manufacturing a resin part according to (1). (3): A method for manufacturing a resin part including a plate-like portion having a plate-like portion and a convex strip portion provided in a convex shape on the plate-like portion, A method for manufacturing a resin part, comprising: molding the convex streak portion and a first region of the plate-like portion including an interface with the convex streak portion; and a second region of the plate-like portion having a uniform thickness, independently of each other, from resin. (4): The resin molding of the second region is performed after the resin molding of the first region. (3) A method for manufacturing a resin part according to the present invention. (5): a first mold defining a first cavity for forming the first region is arranged such that the protruding strip portion is located below the plate-like portion; a second mold defining a second cavity together with the first region for forming the second region is disposed above the first region; (4) A method for manufacturing a resin part according to the present invention. (6): The method for manufacturing a resin part according to (4) or (5), wherein the second region is formed of a resin having a higher transmittance than the resin forming the first region. (7): the first region is formed of a resin whose light spectrum characteristics change depending on the thickness, The method for producing a resin part according to any one of (4) to (6), wherein the second region is formed of a resin whose light spectrum characteristics do not change depending on the thickness. (8): A lighting fixture including a decorative portion, A light source and a transmission portion that transmits light from the light source, the decorative portion including the transmissive portion has a resin layer made of the same type of resin whose transmission spectrum characteristics change depending on the thickness, When light from the light source passes through the resin layer, the transmission spectrum of the light passing through the resin layer differs depending on the portion of the resin layer that has a different thickness. (9): When the light source is turned off, the portions of the resin layer having different thicknesses are dark in color and do not exhibit different colors. When the light source is turned on, the transmission spectrum of light passing through the resin layer varies depending on the portion of the resin layer having a different thickness. (8) A lighting fixture as described above. (10): When the light source is turned on, the resin layer exhibits a pattern when viewed from the thickness direction. the resin layer is covered with a resin whose transmission spectrum characteristics do not change depending on the thickness; A lamp according to claim (8) or (9). (11): The resin layer is unpainted. A lighting fixture according to any one of claims (8) to (10). (12): The resin layer is formed by resin molding. A lighting fixture according to any one of (8) to (11). [Explanation of symbols]

[0071] 1. Emblem 2 Decorative surface 2a Coloring area 2b Non-colored area 3 Casing 10 Light guide 20,120,220 Resin parts 20a, 120a Plate-shaped parts 20b,120b Convex part 111 First cavity mold 112 Second cavity mold 113 Third cavity type 114 Fourth cavity type 115 Fifth cavity type 116 Sixth cavity type 20A, 220A thick part 20B Thin wall part 220B1 First thin section 220B2 Second thin section C1 Plate-shaped cavity C2 Convex part cavity C3 First Region Cavity C4 Second Region Cavity DF molding defect IF interface S1 First area S2 second area

Claims

1. A method for manufacturing a resin part including a plate-like portion having a plate-like portion with a uniform thickness and a protruding portion provided in a protruding shape on the plate-like portion, A method for manufacturing a resin part, wherein the plate-like portion and the protruding portion are each independently molded from resin.

2. the plate-like portion and the protruding portion are formed of a resin whose light spectral characteristics change depending on the thickness; The method for manufacturing the resin part according to claim 1.

3. A method for manufacturing a resin part including a plate-like portion having a plate-like portion and a convex strip portion provided in a convex shape on the plate-like portion, A method for manufacturing a resin part, comprising: molding the convex stripe portion and a first region of the plate-like portion including an interface with the convex stripe portion; and a second region of the plate-like portion having a uniform thickness, independently of each other, from resin.

4. The resin molding of the second region is performed after the resin molding of the first region. The method for manufacturing a resin part according to claim 3.

5. a first mold defining a first cavity for forming the first region is arranged such that the protruding strip portion is located below the plate-like portion; a second mold defining a second cavity together with the first region for forming the second region is disposed above the first region; The method for manufacturing a resin part according to claim 4.

6. The method for manufacturing a resin part according to claim 4 or 5, wherein the second region is formed of a resin having a higher transmittance than the resin forming the first region.

7. the first region is formed of a resin whose light spectrum characteristics change depending on the thickness, The method for manufacturing a resin part according to claim 4 or 5, wherein the second region is formed of a resin whose spectral characteristics of light do not change depending on the thickness.

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