Lighting device

Abstract

The present invention provides a lighting device that can emit light uniformly (or nearly uniformly) across a light-emitting area. [Solution] The lighting device 10 includes a diffuser plate 60 containing a diffuser for scattering light, which has one main surface 61 and the other main surface 62 opposite to it, and an end surface 63 between the one main surface and the other main surface, and at least one light source 52 arranged on the side of the one main surface, wherein the end surface emits light when light enters the diffuser plate from the one main surface and the light from the light source scattered by the diffuser is emitted from the end surface.

Description

[Technical Field]

[0001] This disclosure relates to a lighting device. [Background technology]

[0002] A lighting device is known that comprises a columnar part made of translucent resin and a light source positioned opposite one end face of the columnar part (see, for example, Patent Document 1). In this lighting device, light from the light source enters the columnar part from one end face and exits from the other end face, thereby forming a light-emitting region on the other end face. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2004-361968 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, in the lighting device described in Patent Document 1, since the other end face is positioned on the optical axis of the light source, point light is generated, and there is a problem that the light-emitting area cannot be made to emit light uniformly (or substantially uniformly).

[0005] This disclosure is made to solve these problems and aims to provide a lighting device that can emit light uniformly (or substantially uniformly) across the light-emitting area. [Means for solving the problem]

[0006] The lighting device according to this disclosure comprises a diffuser plate containing a diffuser for scattering light, which includes one main surface and another main surface opposite to it and an end surface between the one main surface and the other main surface, and at least one light source disposed on the side of the one main surface, wherein the end surface emits light when light enters the diffuser plate from the one main surface and the light from the light source, scattered by the diffuser, is emitted from the end surface.

[0007] This configuration allows the light-emitting area to emit light uniformly (or nearly uniformly). Furthermore, the above-described lighting device may further include a first reflective surface arranged on the other main surface side that reflects light from the light source that has passed through the diffuser plate, and the end surface may emit light when light from the light source that enters the diffuser plate from the one main surface and is scattered by the diffuser, and light that enters the diffuser plate from the other main surface and is scattered by the first reflective surface, are emitted from the end surface.

[0008] Furthermore, the above-described lighting device may further include a second reflective surface arranged on one of the main surfaces and reflecting light from the light source, wherein the end surface emits light when light from the light source enters the diffuser plate from the one main surface and is scattered by the diffuser, reflected light from the first reflective surface enters the diffuser plate from the other main surface and is scattered by the diffuser, and reflected light from the second reflective surface enters the diffuser plate from the one main surface and is scattered by the diffuser.

[0009] Furthermore, in the above-described lighting device, the first reflective surface and the second reflective surface may each be high-reflectivity members.

[0010] Furthermore, the above-mentioned lighting device may further include a light-shielding member that surrounds at least a portion of the end face when viewed from the front.

[0011] Furthermore, in the above-described lighting device, the light source may be positioned so that light within the half-angle of the light source's optical axis does not directly emit from the end face.

[0012] In addition, in the above lighting device, the light source may be a film light source including a long film having flexibility and extending in the longitudinal direction, and at least one semiconductor light-emitting element fixed to at least the surface of the film.

[0013] In addition, in the above lighting device, the semiconductor light-emitting elements may be a plurality of semiconductor light-emitting elements having different emission colors, and the semiconductor light-emitting elements may be arranged in the longitudinal direction.

Advantages of the Invention

[0014] According to the present disclosure, it is possible to provide a lighting device capable of emitting light uniformly (or substantially uniformly) in a light-emitting region.

Brief Description of the Drawings

[0015] [Figure 1] It is a front view of the lighting device 10. [Figure 2] It is a cross-sectional view taken along the line A-A of FIG. 1. [Figure 3] It is a front view of the lighting device 10 with the light-shielding member 40 omitted. [Figure 4] It is a diagram for explaining the width W1 etc. of the diffusion plate 60. [Figure 5] It is a front view (partial enlarged view) of the lighting device 10 with the light-shielding member 40 omitted. [Figure 6] It is a comparative example. [Figure 7] It is a modified example of the sealing material 53. [Figure 8] It is a modified example using the reflective layer 70. [Figure 9] It is a modified example in which the diffusion plate 60 is arranged on the outer wall surface 22. [Figure 10] [[ID=4)8]]It is a modified example in which the light source 50 is also arranged on the other main surface 62 side of the diffusion plate 60. [Figure 11] It is a modified example in which a plurality of semiconductor light-emitting elements that emit light of different colors are used as the semiconductor light-emitting element 52.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, an embodiment of the lighting device 10 of this disclosure will be described with reference to the attached drawings. In each figure, corresponding components are denoted by the same reference numerals, and redundant explanations are omitted.

[0017] Figure 1 is a front view of the lighting device 10, Figure 2 is a cross-sectional view AA of Figure 1, and Figure 3 is a front view of the lighting device 10 with the light-shielding member 40 omitted.

[0018] The lighting device 10 of this embodiment is a lighting device capable of forming a narrow, linear light-emitting region. In Figure 1, the hatched region HT is an example of a narrow, linear light-emitting region (the end face 63 of the diffuser plate 60). The lighting device 10 may be applied, for example, to in-vehicle lighting (e.g., interior lighting) or amusement products.

[0019] As shown in Figure 2, the lighting device 10 comprises an intermediate housing 20, a bottom portion 30, a light-shielding member 40, a light source 50, and a diffuser plate 60.

[0020] The intermediate housing 20 is, for example, a rectangular parallelepiped housing that includes a through hole 21 that penetrates one face (the left face in Figure 2) and the other face (the right face in Figure 2). The through hole 21 is a U-shaped through hole in a front view, surrounded by an outer wall surface 22 and an inner wall surface 23 (see Figure 3).

[0021] One end of the through-hole 21 (left side in Figure 2) is closed by a light-shielding member 40 attached to the intermediate housing 20. On the other hand, the other end of the through-hole 21 (right side in Figure 2) is closed by a bottom portion 30 attached to the intermediate housing 20.

[0022] The intermediate housing 20 and the bottom portion 30 are made of a highly reflective material such as white acrylic (or white resin) (for example, a reflective material with a reflectivity of 90% or more, or a reflective material with a reflectivity higher than that of the diffuser plate 60). The outer wall surface 22 and the inner wall surface 23 of the through hole 21 each function as a reflective surface (diffuse reflective surface). The outer wall surface 22 is an example of the first reflective surface of this disclosure, and the inner wall surface 23 is an example of the second reflective surface of this disclosure.

[0023] A light source 50 and a diffuser plate 60 are arranged in the space S1 (see Figure 2) enclosed by the outer wall surface 22 and inner wall surface 23 of the through hole 21, the bottom surface portion 30, and the light-shielding member 40.

[0024] The light source 50 is, for example, a film light source such as an OP-FILM. The film light source includes a long film 51 that is flexible and extends in the longitudinal direction, a plurality of semiconductor light-emitting elements 52 fixed to the film 51, and a sealing material 53 that covers the semiconductor light-emitting elements 52.

[0025] Film 51 is, for example, a transparent film (e.g., a polyimide transparent film). Film 51 may also be a translucent film or an opaque film.

[0026] The semiconductor light-emitting element 52 is a light source with a Lambertsian light distribution characteristic, for example, an LED that emits red light. The emitted color of the semiconductor light-emitting element 52 may be other than red. The semiconductor light-emitting elements 52 are arranged in a row at predetermined intervals along the longitudinal direction of the film 51 (see Figure 3). The arrangement interval of the semiconductor light-emitting elements 52 will be described further later.

[0027] The light source 50 is attached to the inner wall surface 23 of the intermediate housing 20 by known means, such as an adhesive (double-sided tape), while wrapped around the inner wall surface 23. As a result, the semiconductor light-emitting element 52 is positioned on one main surface 61 side of the diffuser plate 60, facing the said main surface 61 with a space S2 (see Figure 2) in between. The sealing material 53 is, for example, a layered sealing material (see Figures 2 and 3) that covers the semiconductor light-emitting element 52. The material of the sealing material 53 is, for example, a silicone resin. The thickness of the layered silicone resin is preferably 350 μm or less, because if it exceeds 350 μm, strong wide-angle light that causes stray light is generated.

[0028] The diffuser plate 60 includes one main surface 61, the other main surface 62 on the opposite side, and an end surface 63 between the two main surfaces 61 and 62 (see Figure 2), and contains a diffuser for scattering light. The transmittance of the diffuser plate 60 is adjusted to 8-70% by adjusting the concentration of the diffuser. By adopting this range, the diffuser plate 60 has a milky white texture, which has the advantage of improving its design and marketability. On the other hand, if this range is exceeded (especially if the upper limit is exceeded), the light-emitting part becomes too white, which reduces its design and marketability. The one main surface 61 and the other main surface 62 are planes parallel to each other and extend, for example, in a U-shape along the inner wall surface 23 of the intermediate housing 20.

[0029] The diffuser plate 60 can be manufactured, for example, by mixing a resin (acrylic resin) with TiO2 white pigment powder, for example, by mixing 90 wt% acrylic resin and 100 wt% TiO2 (for example, with a transmittance of 58%). However, it is not limited to this, and PC (polycarbonate) may be used as the resin. In addition, the white pigment powder may be alumina or the like, as long as it has a higher refractive index than the resin. By adjusting the proportion of resin and white pigment, for example, by increasing the ratio of the white pigment component, the transmittance can be reduced, and diffuser plates with a transmittance of 8-70% can be made. In other words, increasing the weight percentage of white pigment will lower the transmittance, and decreasing the weight percentage will increase the transmittance.

[0030] The end face 63 is, for example, a plane perpendicular to one main surface 61 and the other main surface 62. The diffuser plate 60 is fixed to the light-shielding member 40 by known means such as adhesive or fitting, with the end face 63 exposed through a through hole 41 formed in the light-shielding member 40. In Figure 1, the hatched area HT represents the end face 63. The through hole 41 is configured in a U shape, corresponding to the through hole 21. The end face 63 exposed through the through hole 41 is arranged on the same plane as the surface 42 of the light-shielding member 40 (see Figure 2). Although not shown, the end face 63 may be positioned at a higher level than the surface 42 of the light-shielding member 40, or at a lower level than the surface 42 of the light-shielding member 40.

[0031] Figure 4 is a diagram illustrating the width W1 of the diffuser plate 60, etc. In Figure 4, angle θ1 is the optical axis AX of the semiconductor light-emitting element 52. 52 This represents an angle of +60 degrees relative to the optical axis AX of the semiconductor light-emitting element 52. 52 This represents an angle of -60 degrees relative to the axial direction. These angles θ1 and θ2 are half-power angles and represent the angular range in which the intensity of light emitted from the semiconductor light-emitting element 52 is half of its maximum value. The width W1 of the diffuser plate 60 is the optical axis AX of the semiconductor light-emitting element 52. 52 The dimensions are set so that light within the half-angle maximum (here, angles θ1, θ2, i.e., within an angular range of ±60 degrees) is irradiated onto the surface. Furthermore, the thickness T1 of the diffuser plate 60 is set to a thickness (for example, 2 mm) that takes into consideration the fact that light within the half-angle maximum does not directly emit from the end face 63. It is desirable that the light source 50 (semiconductor light-emitting element 52) ​​be positioned as close to the end face 63 as possible while satisfying the above conditions.

[0032] The brightness (luminance distribution) of the light-emitting region (narrow line-shaped light-emitting region) formed on the end face 63 is adjusted by adjusting the thickness T1 of the diffuser plate 60, the distance L1 between one main surface 61 of the diffuser plate 60 and the inner wall surface 23 of the through hole 21 of the intermediate housing 20, the distance L2 between the other main surface 62 of the diffuser plate 60 and the outer wall surface 22 of the through hole 21 of the intermediate housing 20, and the distance L3 between one main surface 61 of the diffuser plate 60 and the semiconductor light-emitting element 52. The conditions (thickness T1, and conditions for each of the distances L1 to L3) for making the brightness of the light-emitting region formed on the end face 63 uniform (or nearly uniform) can be found using predetermined simulation software.

[0033] Figure 5 is a front view (partially enlarged view) of the lighting device 10 with the light-shielding member 40 omitted. In Figure 5, angle θ3 is the optical axis AX of the semiconductor light-emitting element 52. 52 This represents an angle of +60 degrees relative to the optical axis AX of the semiconductor light-emitting element 52. 52 This represents an angle of -60 degrees relative to θ. These angles θ3 and θ4 are half-power angles and represent the angular range in which the intensity of light emitted from the semiconductor light-emitting element 52 is half of its maximum value. The spacing L4 of the semiconductor light-emitting elements 52 is the optical axis AX of the semiconductor light-emitting element 52 of adjacent semiconductor light-emitting elements 52.52 The light (indicated as Ray1 and Ray2 in Figure 5) within the half-power angle (here, within an angular range of ±60 degrees) is set to be adjacent to the light within the diffuser plate 60 without any gaps (see Figure 5).

[0034] In the lighting device 10 with the above configuration, when the light source 50 (semiconductor light-emitting element 52) ​​is turned on, as shown in Figures 2 and 5, some of the light Ray 1 emitted by the light source 50 (semiconductor light-emitting element 52) ​​enters the diffuser plate 60 from one main surface 61, is scattered by the diffusing agent, and is emitted from the end surface 63 of the diffuser plate 60. In addition, some of the other light Ray 2 emitted by the semiconductor light-emitting element 52 passes through the diffuser plate 60 and is reflected by the outer wall surface 22 of the through hole 21 of the intermediate housing 20. This reflected light Ray 2 enters the diffuser plate 60 from the other main surface 62, is scattered by the diffusing agent, and is emitted from the end surface 63 of the diffuser plate 60. Furthermore, some of the other light Ray 3 (see Figure 5) emitted by the semiconductor light-emitting element 52 is reflected by the inner wall surface 23 of the through hole 21 of the intermediate housing 20. This reflected light Ray3 follows the same optical path as the above-mentioned light Ray1 and Ray2, and is emitted from the end face 63 of the diffuser plate 60.

[0035] As described above, when light rays Ray1 to Ray3 are emitted from the end face 63 of the diffuser plate 60, a narrow, line-shaped light-emitting region (see hatched region HT in Figure 1) is formed on the end face 63 of the diffuser plate 60. At that time, since the light emitted from the light source 50 enters the diffuser plate 60 from both sides (one main surface 61 and the other main surface 62), the light utilization efficiency is improved.

[0036] The inventors have confirmed that when using a diffuser plate 60 with a thickness T1 = 2 mm and transmittance = 58%, a semiconductor light-emitting element 52 with a size of 245 × 135 × 100 μm, and an intermediate housing 20 and bottom surface 30 made of a highly reflective material with reflectance of 90% or more, a narrow line-shaped light-emitting region with a brightness ratio of ±15% (an example of conditions for uniform or substantially uniform visibility) can be formed on the end surface 63.

[0037] Next, the effects of the lighting device 10 with the above configuration will be explained in comparison with a comparative example.

[0038] Figure 6 shows a comparative example.

[0039] As shown in Figure 6, in the comparative example, the semiconductor light-emitting element 52 is positioned facing the end face 64 opposite to the end face 63. The other configurations are the same as those of the lighting device 10 described above.

[0040] In Comparative Example 1, the length L6 (see Figure 6) of the lighting device is increased because the light source 50 (semiconductor light-emitting element 52) ​​is positioned facing the end face 64 opposite to the end face 63. In contrast, the lighting device 10 with the above configuration has the advantage of being able to shorten the length L5 (see Figure 4) of the lighting device because the light source 50 (semiconductor light-emitting element 52) ​​is positioned on one of the main surfaces 61.

[0041] Furthermore, in Comparative Example 1, the optical axis AX of the light source 50 (semiconductor light-emitting element 52) 52 Because the end face 63 is positioned on top (see Figure 6), point light is generated, making it impossible to make the light-emitting region formed on the end face 63 emit light uniformly (or nearly uniformly). In contrast, the lighting device 10 with the above configuration has the advantage that, since light within the half-angle range (here, angles θ1, θ2, i.e., within an angular range of ±60 degrees; see Figure 4) does not directly emit light from the end face 63, point light is suppressed, and the light-emitting region formed on the end face 63 emits light uniformly (or nearly uniformly).

[0042] In Comparative Example 1, uniform light emission can be achieved by widening the width W2 (see Figure 6) of the diffuser plate 60. In contrast, the lighting device 10 with the above configuration has a configuration in which the light source 50 (semiconductor light-emitting element 52) ​​is positioned on one of the main surfaces 61. As a result, the distance between the light-receiving surface (main surface 61) and the light-emitting surface (end surface 63) is shorter compared to Comparative Example 1, which has the advantage that uniform light emission can be achieved even if the width W1 (see Figure 4) of the diffuser plate 60 is narrowed.

[0043] Furthermore, in Comparative Example 1, if the width W2 (see Figure 6) of the diffuser plate 60 is not widened, uniform light emission can be achieved by increasing the concentration of the diffusing agent in the diffuser plate 60. However, increasing the concentration of the diffusing agent reduces the transmittance, and the brightness (luminance) of the light-emitting region (narrow line-shaped light-emitting region) formed on the end face 63 decreases. In contrast, in the lighting device 10 with the above configuration, the light source 50 (semiconductor light-emitting element 52) ​​is positioned on one of the main surfaces 61. As a result, the distance between the light-receiving surface (main surface 61) and the light-emitting surface (end face 63) is shorter compared to Comparative Example 1, so uniform light emission can be achieved without increasing the concentration of the diffusing agent in the diffuser plate 60 (without reducing the transmittance). Therefore, the lighting device 10 with the above configuration has the advantage of suppressing the decrease in brightness (luminance) of the light-emitting region (narrow line-shaped light-emitting region) formed on the end face 63 compared to Comparative Example 1.

[0044] As described above, according to this embodiment, it is possible to provide a lighting device 10 that can emit light uniformly (or substantially uniformly) across the light-emitting area.

[0045] Next, I will explain some variations.

[0046] Figure 7 shows a modified example of the sealing material 53.

[0047] In the above embodiment, an example was described in which a layered encapsulant covering the semiconductor light-emitting element 52 (see Figures 2 and 3) is used as the encapsulant 53, but the invention is not limited to this. For example, as shown in Figure 7, a dome-shaped encapsulant covering the semiconductor light-emitting element 52 may be used as the encapsulant 53. Using a dome-shaped encapsulant has the advantage that the light is focused, the directional characteristics are stabilized, stray light is eliminated, and the effect of thickness is reduced.

[0048] Furthermore, the light source 50 is not limited to a film light source; a light source in which a semiconductor light-emitting element 52 is mounted on a general substrate (for example, a metal substrate) may also be used.

[0049] Figure 8 shows a modified example using the reflective layer 70.

[0050] As shown in FIG. 8, a reflective layer 70 that functions similarly to the outer wall surface 22 may be formed on the other main surface 62 of the diffusion plate 60. The reflective layer 70 may be an aluminum reflective layer or a diffusive reflective layer.

[0051] FIG. 9 is a modified example in which the diffusion plate 60 is disposed on the outer wall surface 22.

[0052] As shown in FIG. 9, the diffusion plate 60 may be disposed on the outer wall surface 22. At that time, the outer wall surface 22 and the other main surface 62 may be adhered, or a gap may be provided between the outer wall surface 22 and the other main surface 62.

[0053] FIG. 10 is a modified example in which the light source 50 is also disposed on the other main surface 62 side of the diffusion plate 60.

[0054] As shown in FIG. 10, the light source 50 may be disposed not only on one main surface 61 side of the diffusion plate 60 but also on the other main surface 62 side of the diffusion plate 60. In this way, for example, even when the thickness T1 becomes thick, a narrow line-shaped light-emitting region that emits light uniformly or substantially uniformly on the end face 63 can be formed.

[0055] FIG. 11 is a modified example in which a plurality of semiconductor light-emitting elements that emit light of different colors are used as the semiconductor light-emitting element 52.

[0056] In the above embodiment, an example in which an LED that emits light of a single color is used as the semiconductor light-emitting element 52 has been described, but the present invention is not limited to this. For example, as shown in FIG. 11, a plurality of semiconductor light-emitting elements that emit light of different colors may be used as the semiconductor light-emitting element 52. FIG. 11 shows an LED 52 that emits red light as the semiconductor light-emitting element 52 R , an LED 52 that emits green light G , an LED 52 that emits blue light B is an example using. In this case, a plurality of semiconductor light-emitting elements (here, LED 52 R , 52 G , 52 BIt is preferable to position the film light source 50 (film 51) in the longitudinal direction (left-right direction in Figure 9). In this way, the width W1 of the diffuser plate 60 (see Figure 5) can be the same length as when an LED that emits single-color light is used as the semiconductor light-emitting element 52.

[0057] Furthermore, although the above embodiment describes an example in which a light-shielding member 40 is used, the invention is not limited to this. For example, the light-shielding member 40 may be omitted, or a transparent member may be used instead of the light-shielding member 40.

[0058] Furthermore, although the above embodiment describes an example in which multiple semiconductor light-emitting elements 52 are used, the invention is not limited to this. There only needs to be one or more semiconductor light-emitting elements 52.

[0059] The numerical values ​​shown in each of the embodiments described above are all examples, and it goes without saying that other appropriate numerical values ​​can be used.

[0060] The embodiments described above are in all respects merely illustrative. The descriptions of the embodiments above should not be construed as limiting the disclosure. The disclosure can be implemented in a variety of other ways without departing from its spirit or main features. [Explanation of Symbols]

[0061] 10…Lighting devices 20…Intermediate cabinet 21…Through hole 22…Exterior wall surface 23…Interior wall surface 30…Bottom part 40…Light-shielding material 41…Through hole 42…Surface 50...Light source 51…film 52… Semiconductor light-emitting element 52B, 52G, 52R…LED 53… Sealing material 60... Diffuser 61... One main side 62... The other main surface 63…End face 64...End face 70…Reflection layer AX 52 …optical axis HT... Hatching area Ray1~2...Light S1, S2…space T1...Thickness θ1~θ4…Angle

Claims

1. A diffuser plate comprising one main surface, the other main surface opposite to it, and an end surface between the one main surface and the other main surface, and containing a diffuser for scattering light, The system comprises at least one light source arranged on one of the main surfaces, The end face is a lighting device that emits light when light enters the diffuser plate from one of the main surfaces and is scattered by the diffuser, and then exits from the end face.

2. The other main surface side further comprises a first reflective surface that reflects light from the light source that has passed through the diffuser plate, The lighting device according to claim 1, wherein the end face emits light when light from the light source is received by the diffuser from one main surface and scattered by the diffuser, and when light from the first reflective surface is received by the diffuser from the other main surface and scattered by the diffuser, the end face emits light.

3. It further comprises a second reflective surface arranged on one of the main surfaces and reflecting light from the light source, The lighting device according to claim 2, wherein the end face emits light when light from the light source is received by the diffuser from one main surface and scattered by the diffuser, light from the first reflective surface is received by the diffuser from the other main surface and scattered by the diffuser, and light from the second reflective surface is received by the diffuser from one main surface and scattered by the diffuser.

4. The lighting device according to claim 3, wherein the first reflective surface and the second reflective surface are each high-reflectivity members.

5. The lighting device according to claim 1, further comprising a light-shielding member that surrounds at least a portion of the end face when viewed from the front.

6. The lighting device according to claim 1, wherein the light source is positioned such that light within the half-angle of maximum relative to the optical axis of the light source does not directly emit light from the end face.

7. The lighting device according to claim 1, wherein the light source is a film light source comprising a flexible and elongated film extending in the longitudinal direction, and at least one semiconductor light-emitting element fixed to at least the surface of the film.

8. The semiconductor light-emitting element is a plurality of semiconductor light-emitting elements that emit light in colors different from each other. The lighting device according to claim 7, wherein the semiconductor light-emitting element is arranged in the longitudinal direction.

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