Microlens array and vehicle lamp using the microlens array

Abstract

A micro lens array (7) includes a plurality of optical systems (70). Each optical system (70) includes a pair of an entrance-side lens portion (71) and an exit-side lens portion (72). A low refractive index portion (73) is provided between an entrance surface of the entrance-side lens portion (71) and an exit surface of the exit-side lens portion (72). The refractive index of the low refractive index portion (73) is lower than the refractive index of other parts. The low refractive index portion (73) includes a first surface (731) extending through a focal point of the exit surface, and a second surface (732) extending from the first surface (731) toward the entrance surface. A boundary portion (733) of the first surface (731) and the second surface (732) constitutes a cut line forming portion. The entrance surface is provided in a position that does not overlap the second surface (732) in a front view of the entrance-side lens portion (71).

Description

[Technical Field]

[0001] The present disclosure relates to a microlens array and a vehicle lamp using the microlens array. [Background technology]

[0002] BACKGROUND ART Patent Document 1 and other documents disclose a vehicle lamp that illuminates the area ahead of the lamp via a microlens array. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2016-534503 Summary of the Invention [Problem to be solved by the invention]

[0004] The microlens array described in Patent Document 1 includes a light shielding plate between the rear lens array and the front lens array. This light shielding plate blocks part of the light emitted from the light source unit, thereby forming a low-beam light distribution pattern with a cutoff line.

[0005] Furthermore, the optical systems of the microlens array described in Patent Document 1 are arranged in a first direction and a second direction perpendicular to the first direction. The exit-side lens portion of each optical system has an exit surface that is curved when viewed from both the first direction (e.g., the vertical direction) and the second direction (e.g., the horizontal direction) perpendicular to the first direction.

[0006] In such vehicle lamps, a portion of the light emitted from the light source is blocked by the light blocking plate and is not emitted forward of the lamp, so there is room for improvement in the light utilization efficiency.

[0007] An object of the present disclosure is to provide a microlens array with high light utilization efficiency and a vehicle lamp using the microlens array.

[0008] The inventors have also investigated a configuration in which part of the light emitted from the light source is emitted forward without being blocked in order to increase the efficiency of light use, and at the same time, a configuration in which the occurrence of glare is reduced.

[0009] An object of the present disclosure is to provide a microlens array that increases light utilization efficiency while reducing the occurrence of glare, and a vehicle lamp that uses the microlens array.

[0010] Furthermore, the microlens array in Patent Document 1 is configured to effectively focus light that has passed through the microlens array and project a light distribution pattern, but in order to diffuse the emitted light over a wider area, a microlens array with a new configuration was needed.

[0011] An object of the present disclosure is to provide a microlens array that diffuses emitted light more widely and a vehicle lamp using the microlens array. [Means for solving the problem]

[0012] The microlens array according to the first aspect of the present disclosure comprises: A microlens array having a plurality of optical systems, Each of the optical systems includes a pair of an incident-side lens unit and an exit-side lens unit, a low refractive index portion is provided between the incident surface of the incident-side lens portion and the exit surface of the exit-side lens portion, The refractive index of the low refractive index portion is lower than the refractive index of the other portions, the low refractive index portion includes a first surface extending through a focal point of the exit surface and a second surface extending from the first surface to the entrance surface; a cut line forming portion is formed by a boundary portion between the first surface and the second surface, When viewed from the front of the incident-side lens portion, the incident surface is provided at a position that does not overlap with the second surface.

[0013] A vehicle lamp according to a second aspect of the present disclosure includes: A light source and and the microlens array according to the first aspect.

[0014] A microlens array according to a third aspect of the present disclosure includes: A microlens array having a plurality of optical systems, Each of the optical systems includes a pair of an incident-side lens unit and an exit-side lens unit, a low refractive index portion is provided between the incident surface of the incident-side lens portion and the exit surface of the exit-side lens portion, the refractive index of the low refractive index portion is lower than the refractive index of the other portions, the low refractive index portion includes a first surface extending through a focal point of the exit surface and a second surface extending from the first surface to the entrance surface; a cut line forming portion is formed by a boundary portion between the first surface and the second surface, The ratio A:B of a thickness A from the entrance surface of the entrance-side lens portion to the boundary portion and a thickness B from the boundary portion to the exit surface of the exit-side lens portion is 1.8:1 or more.

[0015] A vehicle lamp according to a fourth aspect of the present disclosure includes: A light source and and a microlens array according to the third aspect.

[0016] A microlens array according to a fifth aspect of the present disclosure includes: A microlens array comprising a plurality of optical systems, Each of the optical systems has a pair of an incident-side lens portion and an exit-side lens portion, The plurality of optical systems are arranged in at least a first direction and a second direction perpendicular to the first direction, At least a part of the optical system has an exit surface of the exit-side lens portion that forms a plane when viewed from the first direction and a curved surface when viewed from the second direction, and constitutes a diffusion section.

[0017] A vehicle lamp according to a sixth aspect of the present disclosure includes: A light source and A microlens array according to the fifth aspect; and a primary lens that causes light emitted from the light source to enter the microlens array. [Effects of the Invention]

[0018] According to the present disclosure, it is possible to provide a microlens array that increases light utilization efficiency while reducing the occurrence of glare, and a vehicle lamp using the microlens array.

[0019] According to the present disclosure, it is possible to provide a microlens array with high light utilization efficiency and a vehicle lamp using the microlens array.

[0020] According to the present disclosure, it is possible to provide a microlens array that diffuses emitted light more widely and a vehicle lamp using the microlens array. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic cross-sectional view of a vehicle lamp according to an embodiment of the present disclosure, viewed from the left and right direction; [Figure 2] FIG. 2 is a cross-sectional view of the microlens array according to the first embodiment, viewed from the right. [Figure 3] 1 is a cross-sectional view of a microlens array according to a first embodiment, viewed from above. [Figure 4] FIG. 3 is a partially enlarged view of the microlens array of FIG. 2. [Figure 5] 5 is a schematic diagram of the optical system of FIG. 4 as viewed from the incident-side lens portion side. [Figure 6] FIG. 10 is a partially enlarged view of a microlens array in which the lower surface of the incident surface is positioned lower than the second surface. [Figure 7] 7 is a diagram showing a light distribution pattern formed by a vehicle lamp equipped with the microlens array of FIG. 6. FIG. [Figure 8]3 is a diagram showing a light distribution pattern formed by a vehicle lamp including the microlens array of FIG. 2. FIG. [Figure 9] FIG. 10 is a cross-sectional view of a modified example of the exit-side lens portion as viewed from the right. [Figure 10] 10 is a schematic diagram of a modified example of the exit-side lens portion in FIG. 9, viewed from the exit-side lens portion side. FIG. [Figure 11] 10 is a partially enlarged view of the microlens array having the exit-side lens portion of FIG. 9. [Figure 12] FIG. 10 is a side view of a microlens array according to a second embodiment. [Figure 13] Show the relationship between the ratio of the lens thickness of an optical system and the luminous efficiency and crosstalk ray ratio. [Figure 14] 13 is a partially enlarged view of the microlens array shown in FIG. 12. [Figure 15] FIG. 11 is a cross-sectional view of a microlens array having a diffusion portion according to a third embodiment, as viewed from the right. [Figure 16] FIG. 11 is a cross-sectional view of a microlens array having a diffusion portion according to a third embodiment, as viewed from above. [Figure 17] FIG. 10 is a cross-sectional view of a microlens array having a light distribution forming portion as viewed from the right side. [Figure 18] FIG. 10 is a cross-sectional view of a microlens array having a light distribution forming portion as viewed from above. [Figure 19] FIG. 2 is a front view of exit-side lens portions of a plurality of optical systems that make up the microlens array. [Figure 20] FIG. 2 is a cross-sectional view of the vehicle lamp as viewed from above. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, examples of embodiments of the present disclosure will be described with reference to the drawings. The same or equivalent components and members shown in each drawing will be assigned the same reference numerals, and duplicate descriptions will be omitted as appropriate. In addition, the scale of each drawing has been changed as appropriate to make each member recognizable.

[0023] Furthermore, the embodiments are examples and do not limit the invention, and all of the features and combinations thereof described in the embodiments are not necessarily essential to the invention.

[0024] Furthermore, in the description of this embodiment, for convenience of explanation, the "left-right direction," "front-rear direction," and "up-down direction" will be referred to as appropriate. Here, the "up-down direction" is a direction that includes the "upward direction" and the "downward direction." The "front-rear direction" is a direction that includes the "forward direction" and the "rearward direction." The "left-right direction" is a direction that includes the "leftward direction" and the "rightward direction." In the drawings described below, the symbol U indicates the upward direction. The symbol D indicates the downward direction. The symbol F indicates the forward direction. The symbol B indicates the rearward direction. The symbol L indicates the leftward direction. The symbol R indicates the rightward direction. Note that when the microlens array and the vehicular lamp are attached to a vehicle, these directions do not necessarily coincide with the respective directions set for the vehicle.

[0025] Fig. 1 is a schematic cross-sectional view of a vehicle lamp 1 according to an embodiment of the present disclosure. As shown in Fig. 1, the vehicle lamp 1 includes an outer cover 2 and a housing 3. The outer cover 2 and the housing 3 form a lamp chamber 4.

[0026] The lamp chamber 4 is provided with a light source 5, a primary lens 6, and a microlens array 7. The light source 5 is mounted on a substrate 501 supported by the housing 3 and is arranged facing forward. For example, an LED (Light Emitting Diode) or an LD (Laser Diode) can be used as the light source 5. Light emitted from the light source 5 passes through the primary lens 6 and the microlens array 7 and is emitted forward of the vehicle lamp 1. In the following description, an imaginary straight line extending from the center point of the light emitting surface of the light source 5 in the fore-and-aft direction of the vehicle lamp 1 will be referred to as the main optical axis Mx of the vehicle lamp 1.

[0027] The primary lens 6 converts light emitted from the light source 5 into parallel light and causes it to enter the microlens array 7. The primary lens 6 can be a collimator lens, an aplanat lens, a Fresnel lens, or the like. The primary lens 6 shown in FIG. 1 has a first incident portion 61 provided at a position facing the light source 5 and a second incident portion 62 provided as a vertical wall surrounding the first incident portion 61. Light B1 incident from the light source 5 to the first incident portion 61 is refracted at the first incident portion 61 to become parallel light having a main optical axis Mx. Light B2 incident from the light source 5 to the second incident portion 62 is reflected by a reflecting surface 63 to become parallel light having a main optical axis Mx.

[0028] 1, one light source unit is made up of the light source 5, the primary lens 6, and the microlens array 7. The vehicle lamp 1 may be provided with a plurality of light source units in the same lamp chamber 4.

[0029] The microlens array 7 is an optical component made of, for example, a transparent resin material or a glass material.

[0030] (First embodiment) Next, the microlens array 7 according to the first embodiment will be described in detail with reference to Fig. 2 to Fig. 4. Fig. 2 is a cross-sectional view of the microlens array 7 of Fig. 1 as viewed from the right. Fig. 3 is a cross-sectional view of the microlens array 7 of Fig. 1 as viewed from above. Fig. 4 is a partially enlarged view of the microlens array 7 of Fig. 2. Fig. 5 is a schematic view of the optical system 70a of the microlens array 7 of Fig. 4 as viewed from the incident-side lens portion 71 side.

[0031] As shown in FIGS. 2 and 3, the microlens array 7 has a plurality of optical systems 70. The optical systems 70 are adjacent to each other in a direction perpendicular to the light emission direction (main optical axis Mx: optical axis Ax of the incident-side lens portion 71), and the optical systems 70 are integrated. In this embodiment, the plurality of optical systems 70 are arranged adjacent to each other in the vertical and horizontal directions. In the illustrated microlens array 7, the optical systems 70 have the same shape and dimensions. The size of the optical system 70 (each microlens) is arbitrary, but is preferably approximately 0.5 to 10 mm square, and more preferably approximately 0.5 to 5 mm square, when viewed from the front in the irradiation direction. The thickness of the optical system 70 in the front-to-rear direction is preferably 3 mm to 40 mm.

[0032] Each optical system 70 includes a pair of incident-side lens portion 71 and exit-side lens portion 72, and a low-refractive-index portion 73. For example, as shown in Fig. 2, optical system 70a includes a portion of incident-side lens portion 71 that includes incident surface 71a, a portion of exit-side lens portion 72 that includes exit surface 72a, and a low-refractive-index portion 73a. The same applies to optical systems 70b to 70f.

[0033] The incident-side lens portion 71 is provided closer to the primary lens 6 than the low-refractive-index portion 73. The exit-side lens portion 72 is provided closer to the outer cover 2 than the low-refractive-index portion 73. The incident-side lens portion 71 and the exit-side lens portion 72 are provided on a common optical axis Ax and face each other. The optical axis Ax of each optical system 70 is parallel to the main optical axis Mx of the vehicle lamp 1. Note that FIG. 2 only shows the optical axis Ax of the optical system 70d. Light incident on the incident-side lens portion 71 of a certain optical system 70 is basically configured to be incident on the exit-side lens portion 72 belonging to the same optical system 70.

[0034] The incident-side lens portion 71 and the exit-side lens portion 72 each have a convex lens shape. For example, as shown in Fig. 2, the incident surface of the incident-side lens portion 71 and the exit surface of the exit-side lens portion 72 each form a curved surface with a single radius of curvature when viewed from the left and right. Furthermore, for example, as shown in Fig. 3, the incident surface of the incident-side lens portion 71 and the exit surface of the exit-side lens portion 72 each form a curved surface with a single radius of curvature when viewed from the top and bottom.

[0035] The low refractive index portion 73 is provided between a pair of incident-side lens portion 71 and exit-side lens portion 72 that form one optical system 70. For example, the low refractive index portion 73 penetrates the microlens array 7 in the left-right direction. In this example, the shape of the low refractive index portion 73 when viewed from the left-right direction is approximately rectangular, but it may be another shape, such as approximately triangular.

[0036] The low refractive index portion 73 is configured so that its refractive index is lower than the refractive index of other parts constituting the optical system 70 (the incident-side lens portion 71, the exit-side lens portion 72, and the portion connecting the incident-side lens portion 71 and the exit-side lens portion 72). For example, the low refractive index portion 73 is a hollow portion containing, for example, air. Alternatively, the low refractive index portion 73 may be made of a material different from the material constituting the other parts. The difference in refractive index between the low refractive index portion 73 and the other parts is preferably 0.03 or more, and more preferably 0.05 or more. The low refractive index portion 73 may be a sealed closed region or an unsealed open region.

[0037] As shown in FIG. 2 , the low-refractive-index portion 73 includes a first surface 731 extending through the focal point f of the exit-side lens portion 72 and a second surface 732 extending from the first surface 731 to the incident surface of the incident-side lens portion 71. A boundary 733 between the first surface 731 and the second surface 732 defines a cutline forming portion. The cutline forming portion defines a cutline in the light distribution pattern formed by the vehicular lamp 1. In this embodiment, the first surface 731 is a surface extending in the up-down and left-right directions. The second surface 732 is a surface extending in the front-rear and left-right directions. The second surface 732 is configured to totally reflect light that enters the corresponding incident-side lens portion 71 and reaches the second surface 732, for example.

[0038] The incident surface 71a of the incident side lens portion 71 is located at a position that does not overlap with the second surface 732 when viewed from the front of the incident side lens portion 71. For example, as shown in FIGS. 4 and 5, in the optical system 70a, the lower surface 71aE of the incident surface 71a of the incident side lens portion 71 is located higher than the second surface 732. In other words, the incident surface 71a of the incident side lens portion 71 is located at a position that does not overlap with the second surface 732 when viewed from the front of the incident side lens portion 71. Furthermore, the incident surface 71a of the incident side lens portion 71 is located on the opposite side of the optical axis Ax from the low refractive index portion 73a.

[0039] 2, for example, a portion of light B3 incident on an incident-side lens portion 71 of an optical system 70 travels toward a paired output-side lens portion 72 and is emitted from the output surface of the output-side lens portion 72. Of the light incident on the incident-side lens portion 71, light B4 would otherwise be emitted above the cut line of the light distribution pattern and become glare, and is reflected by the second surface 732 of the low-refractive index portion 73 and is incident on the output-side lens portion 72. Therefore, the light utilization efficiency can be improved while suppressing the occurrence of glare.

[0040] However, depending on the positional relationship between the incident surface of incident-side lens portion 71 and second surface 732, some of the light incident on incident-side lens portion 71 may enter low-refractive-index portion 73 from a surface other than second surface 732. In this case, light that passes through low-refractive-index portion 73 and enters output-side lens portion 72 may be emitted upward from output surface 72a, which may cause glare.

[0041] 6 is a diagram showing optical system 170a in which lower end 171aE of incident surface 171a is located below second surface 1732. As shown in FIG. 6, light B15 that is incident on a portion of incident surface 171a of incident-side lens portion 171 that is located below second surface 1732 is incident on low-refractive-index portion 173a from side surface 1734 of low-refractive-index portion 173a. Light B15 that is incident on low-refractive-index portion 173a passes through low-refractive-index portion 173a and is emitted upward from the exit surface of exit-side lens portion 172.

[0042] FIG. 7 shows a light distribution pattern P1 formed by a vehicle lamp including a microlens array having optical system 170a. In FIG. 7, HH indicates the horizontal direction (horizontal line H), and VV indicates the vertical direction (vertical line V). The light distribution pattern P1 is a light distribution pattern formed on a virtual vertical screen placed at a predetermined position in front of the lamp, for example, 25 m in front of the lamp. As shown in FIG. 7, the light distribution pattern P1 has a shape that includes an irradiation area (the area surrounded by a dashed line in FIG. 7) located above the cut line. That is, as described above, light that passes through low refractive index portion 173a and is emitted upward from the exit surface of output-side lens portion 72 is irradiated above the cut line, resulting in glare.

[0043] In contrast, in the microlens array 7 according to this embodiment, as shown in FIG. 4, the lower surface 71aE of the incident surface 71a of the incident-side lens portion 71 is located above the second surface 732. That is, since there is no portion of the incident surface 71a located below the second surface 732, the amount of light entering the low-refractive-index portion 73 from the side surface 734 of the low-refractive-index portion 73 is significantly reduced. In other words, most of the light entering the incident-side lens portion 71 is directly incident on the output-side lens portion 72, or is reflected by the second surface 732 of the low-refractive-index portion 73 and then enters the output-side lens portion 72 (light B5 in FIG. 4). This reduces glare, and as shown in FIG. 8, the vehicular lamp 1 including the microlens array 7 can form a light distribution pattern P2 having a desired shape including a cut line.

[0044] In this embodiment, the exit surface of exit-side lens portion 72 is a curved surface having a single radius of curvature when viewed from the left-right direction and the top-bottom direction. However, as shown in Fig. 9, for example, the exit surface of exit-side lens portion 72A may have first region 721 and second region 722 with different radii of curvature.

[0045] Fig. 10 is a schematic diagram of the output-side lens portion 72A of Fig. 9 as viewed from the output-side lens portion 72A side. As shown in Fig. 10, for example, a boundary line BL separating a first region 721 and a second region 722 is a line extending in the left-right direction, and the first region 721 is located above the second region 722. In this example, the first region 721 and the second region 722 are separated such that the optical axis Ax of the output-side lens portion 72A passes through the boundary line BL.

[0046] The first region 721 has a radius of curvature whose focal point is located at the cut line formation portion. The second region 722 has a radius of curvature larger than the radius of curvature of the first region 721. For example, the radius of curvature of the second region 722 is preferably 1.1 to 1.5 times the radius of curvature of the first region 721.

[0047] The first region 721 is formed to have a curved surface with a single radius of curvature when viewed from above and below as shown in Fig. 3. The second region 722 is also formed to have a curved surface with a single radius of curvature when viewed from above and below as shown in Fig. 3.

[0048] When the exit surface of the exit side lens portion 72 has a single radius of curvature when viewed from the left and right, some of the light that enters through the incident surface of the exit side lens portion 72 and reaches the exit surface of the exit side lens portion 72 may be emitted upward from the exit surface, causing glare (see light B16 in Figure 11).

[0049] In contrast, in output-side lens unit 72A, the degree of refraction of light emitted from second region 722 is small, so that light B6 that enters through incident surface 71a of input-side lens unit 71 and enters second region 722 of the output surface of output-side lens unit 72A is emitted more downward than light B16 that exits from the output surface having a single radius of curvature, as shown in Figure 11. This makes it possible to suppress the occurrence of glare.

[0050] Note that such a configuration of the exit-side lens portion 72A may be applied to all or some of the exit-side lens portions 72 that constitute the microlens array 7. For example, the exit-side lens portion 72A may be applied to the exit-side lens portion 72 that is paired with the entrance-side lens portion 71 that has a large radius of curvature of the incident surface and is configured to diffuse light.

[0051] 9 can also be applied to optical systems having a configuration other than that of optical system 70 in Fig. 2. For example, the configuration of exit-side lens section 72A can also be applied to an optical system in which the lower surface of the incident surface is located at the same level as or below second surface 732 of low refractive index section 73.

[0052] Second Embodiment Next, the microlens array 7 according to the second embodiment will be described in detail with reference to Fig. 12 to Fig. 14. Fig. 12 is a side view of the microlens array 7 shown in Fig. 1.

[0053] As shown in FIG. 12, the microlens array 7 has a plurality of optical systems 70. The optical systems 70 are adjacent to each other in a direction perpendicular to the light emission direction (main optical axis Mx: optical axis Ax of the incident-side lens portion 71), and the optical systems 70 are integrated. Since a plurality of lens components are integrated into a single microlens array 7, the positioning precision of each optical system 70 is high. Furthermore, handling, such as portability, is easy. The size of the optical system 70 (each microlens) is arbitrary, but is preferably approximately 0.5 to 10 mm square when viewed from the front in the irradiation direction, and more preferably approximately 0.5 to 5 mm square. Furthermore, the thickness of the optical system 70 in the front-to-rear direction is preferably 3 mm to 40 mm.

[0054] 12, each optical system 70 includes a pair of incident-side lens portion 71 and exit-side lens portion 72, and a low-refractive-index portion 73. For example, optical system 70a includes a portion of incident-side lens portion 71 that includes incident surface 71a, a portion of exit-side lens portion 72 that includes exit surface 72a, and a low-refractive-index portion 73a. The same applies to optical systems 70b to 70f.

[0055] The incident-side lens portion 71 is located closer to the primary lens 6 than the low-refractive-index portion 73. The exit-side lens portion 72 is located closer to the outer cover 2 than the low-refractive-index portion 73. The incident-side lens portion 71 and the exit-side lens portion 72 are located on a common optical axis Ax and face each other. The optical axis Ax of each optical system 70 is parallel to the main optical axis Mx of the vehicle lamp 1. The incident-side lens portion 71 and the exit-side lens portion 72 each have a convex lens shape. In the illustrated microlens array 7, each optical system 70 has the same shape and dimensions. The focal length of the exit-side lens portion 72 is equal to or less than the lens thickness D of the incident-side lens portion 71.

[0056] The low refractive index portion 73 is provided between a pair of incident-side lens portion 71 and exit-side lens portion 72 that form one optical system 70. The low refractive index portion 73 penetrates the microlens array 7 in a first direction (the left-right direction in the example of FIG. 12). In this example, the shape of the low refractive index portion 73 when viewed from the left-right direction is approximately rectangular, but it may be another shape, such as approximately triangular.

[0057] The low refractive index portion 73 is configured so that its refractive index is lower than the refractive index of other parts constituting the optical system 70 (the incident-side lens portion 71, the exit-side lens portion 72, and the portion connecting the incident-side lens portion 71 and the exit-side lens portion 72). For example, the low refractive index portion 73 may be hollow and may contain, for example, air. Alternatively, the low refractive index portion 73 may be made of a material different from the material constituting the other parts. The difference in refractive index between the low refractive index portion 73 and the other parts is preferably 0.03 or more, and more preferably 0.05 or more. The low refractive index portion 73 may be a sealed closed region or an unsealed open region.

[0058] The low refractive index portion 73 includes a first surface 731 extending through the focal point f of the exit-side lens portion 72 and a second surface 732 extending from the first surface 731 to the incident surface of the incident-side lens portion 71. A boundary portion 733 between the first surface 731 and the second surface 732 defines a cut line forming portion. In this embodiment, the first surface 731 is a surface extending in the up-down direction and the left-right direction. The second surface 732 is a surface extending in the front-rear direction and the left-right direction. The second surface 732 is configured to totally reflect light that enters the corresponding incident-side lens portion 71 and reaches the second surface 732, for example.

[0059] Light incident on an incident-side lens unit 71 of a given optical system 70 is generally incident on an exit-side lens unit 72 belonging to the same optical system 70. For example, as shown in FIG. 12 , light B11 incident on the incident-side lens unit 71 travels toward the paired exit-side lens unit 72 and is emitted from the exit surface of the exit-side lens unit 72. However, light emitted from a light source tends to spread radially, although the degree of spread varies depending on the type of light source. For this reason, even if the shape of the incident-side lens unit is adjusted, light emitted from the light source and incident on the incident-side lens unit may not reach the paired exit-side lens unit. In this embodiment, the microlens array 7 includes a low-refractive index portion 73 having a second surface 732. This allows at least a portion of the light (light B12) incident on the incident-side lens unit 71 that would not otherwise enter the paired exit-side lens unit 72 to be reflected by the second surface 732 of the low-refractive index portion 73 and incident on the paired exit-side lens unit 72.

[0060] Each optical system 70 is formed so that the ratio A:B of the thickness A from the incident surface of the incident-side lens portion 71 to the boundary portion 733 to the thickness B from the boundary portion 733 to the exit surface of the exit-side lens portion 72 is 1.8:1 or greater. In this specification, the term "thickness" refers to the thickness in the direction along the optical axis Ax (the front-to-rear direction in the example of FIG. 12). More specifically, the thickness A is the dimension from the most protruding portion of the incident surface of the incident-side lens portion 71 to the boundary portion 733 on the optical axis Ax. The thickness B is the dimension from the boundary portion 733 to the most protruding portion of the exit surface of the exit-side lens portion 72 on the optical axis Ax.

[0061] Fig. 13 illustrates the relationship between the ratio A:B of the lens thicknesses in the optical system 70 and the luminous efficiency and crosstalk ray rate. In Fig. 13, the horizontal axis represents the ratio A:B. The vertical axis represents the luminous efficiency and crosstalk rate. The black triangles represent the luminous efficiency values, and the black circles represent the crosstalk ray rate values.

[0062] Luminous efficiency (%) is a reference value calculated using simulation software. The crosstalk ray ratio (%) indicates the ratio of light incident on the incident surface of the incident-side lens portion 71 to the incident surface of the adjacent, unpaired, output-side lens portion 72 (the occurrence ratio of so-called optical crosstalk). The crosstalk ray ratio (%) is calculated by {(CP / 2) / C}×100.

[0063] Here, as shown in FIG. 14, P is the pitch of the incident-side lens portions 71 (exit-side lens portions 72). C is the height of light B13, which is incident on the incident surface 71a of the incident-side lens portion 71 and enters the exit surface 72b of the adjacent, unpaired, exit-side lens portion 72 (the height relative to light B14, which is incident on the exit surface 72a of the paired exit-side lens portion 72 along the optical axis Ax). CP / 2 is the height of the portion of light B13, which is incident on the exit surface 72b of the adjacent exit-side lens portion 72 and extends beyond the adjacent exit-side lens portion 72. Note that in this specification, "height" refers to the height in the direction perpendicular to the optical axis Ax (the up-down direction in FIG. 13). Furthermore, since the relationship P:C = A:B holds, the crosstalk light rate (%) can be calculated by {(CP / 2) / C} × 100 = (1 - A / 2B) × 100.

[0064] As shown in Figure 13, the rate of optical crosstalk occurrence decreased as the ratio A:B increased, and when the ratio A:B was 2:1 or greater, the rate of optical crosstalk occurrence became zero. In other words, it was found that, theoretically, optical crosstalk does not occur when the ratio A:B is 2:1 or greater. Therefore, several samples were actually produced to check the rate of optical crosstalk occurrence. It was confirmed that optical crosstalk occurrence can be suppressed when the ratio A:B is 1.8 or greater, regardless of dimensional errors in each part.

[0065] As described above, the optical system 70 according to this embodiment is formed so that the ratio A:B is 1.8:1 or greater, which can prevent crosstalk from occurring, in which a portion of light incident from the incident-side lens portion 71 is not reflected by the second surface 732 of the low-refractive-index portion 73 and instead enters an adjacent, non-paired, output-side lens portion 72. Furthermore, light incident from the incident-side lens portion 71 and reflected by the second surface 732 of the low-refractive-index portion 73 can also be prevented from entering an adjacent, non-paired output-side lens portion 72. This can improve light utilization efficiency.

[0066] 13, the luminous efficiency increases as the ratio A:B increases, and the luminous efficiency saturates when the ratio A:B is 2.5:1 or greater. On the other hand, the larger the ratio A:B in the optical system 70, the larger the size of the image projected by the optical system 70 tends to be. Therefore, it is preferable that each optical system 70 is formed so that the ratio A:B is 2.5:1 or less. By forming the optical system 70 so that the ratio A:B is 2.5:1 or less, it is possible to prevent the projected image from becoming too large relative to the desired projected image.

[0067] Unlike the example shown in Figure 14 (a configuration in which the incident side lens portion 71 is located on the optical axis Ax), in a configuration in which a portion of the incident side lens portion 71 is removed and the incident side lens portion 71 is not located on the optical axis Ax, the thickness A means the length of a virtual line extending from a virtual point located on the optical axis Ax on the virtually extended incident surface along the optical axis Ax to the boundary portion 733 when the incident surface is virtually extended to a position where it intersects with the optical axis Ax while maintaining the curvature of the incident surface of the existing incident side lens portion 71. However, in reality, the amount of deviation in the optical axis direction between the "most protruding portion of the entrance surface of entrance-side lens portion 71" and the "imaginary point" is extremely small compared to the other dimensions B, C, and P. For this reason, even if the above formula is calculated using the distance in the optical axis Ax direction from the "most protruding portion of the existing entrance surface of entrance-side lens portion 71" to boundary portion 733 as thickness A, it does not have a significant effect on the numerical range of 1.8 or 2.5.

[0068] (Third embodiment) Next, a microlens array 7 according to a third embodiment will be described with reference to Fig. 15 and Fig. 16. Fig. 15 is a cross-sectional view of the microlens array 7 having the diffusion portion 40 as viewed from the right. Fig. 16 is a cross-sectional view of the microlens array 7 having the diffusion portion 40 as viewed from above.

[0069] The microlens array 7 has a plurality of optical systems 41. The plurality of optical systems 41 are arranged adjacent to each other in the vertical direction (an example of a first direction) and the horizontal direction (an example of a second direction). In the illustrated microlens array 7, each optical system 41 has the same shape and dimensions. Each optical system 41 is a single optical component made of a transparent resin material, glass material, or the like. The size of the optical systems 41 is arbitrary, but, for example, a single optical system 41 is desirably 0.5 mm to 10 mm square, and more desirably 0.5 mm to 5 mm square, when viewed from the front. Furthermore, the thickness of the optical system 41 in the front-to-back direction is desirably 3 mm to 40 mm.

[0070] Each optical system 41 has a pair of incident-side and exit-side lens portions 42 and 43, and a cavity 44. The incident-side lens portion 42 is located closer to the primary lens 6 than the cavity 44. The exit-side lens portion 43 is located closer to the outer cover 2 than the cavity 44. The incident-side lens portion 42 and the exit-side lens portion 43 face each other and share a common optical axis Ax2. The optical axis Ax2 is parallel to the main optical axis Mx. The incident-side lens portion 42 has a convex lens shape. The incident-side lens portion 42 is configured to direct light incident by the primary lens 6 to the corresponding exit-side lens portion 43. It is desirable that the focal point of the incident-side lens be near the cavity 44, which will be described later.

[0071] The cavity 44 is provided between the incident-side lens portion 42 and the exit-side lens portion 43 that form one optical system 41. The cavity 44 is a cavity that penetrates the microlens array 7 in the left-right direction. Any medium, such as air, exists inside the cavity 44. The cavity may be a sealed closed region or an unsealed open region. The cavity 44 illustrated in FIG. 15 is an open region.

[0072] As shown in Figure 15, the hollow portion 44 has a first surface 44A and a second surface 44B. The first surface 44A is on a plane including the up-down direction and the left-right direction. The second surface 44B is on a plane including the front-rear direction and the left-right direction. A cut line forming portion is formed by the boundary between the first surface 44A and the second surface 44B. It is desirable to configure the second surface 44B so that light that is incident from the corresponding incident-side lens portion 42 and reaches the second surface 44B is totally reflected.

[0073] Exit-side lens portion 43 emits light that has passed through optical system 41 and entered exit-side lens portion 43 toward outer cover 2. Here, as shown in Fig. 15, the exit surface of exit-side lens portion 43 is curved when viewed from the left and right. Also, as shown in Fig. 16, the exit surface of exit-side lens portion 43 is flat when viewed from the top and bottom. When the exit surface of the exit side lens section 43 is viewed from the left and right, the exit surface is curved, and when the exit surface of the exit side lens section 43 is viewed from the top and bottom, the exit surface is flat. The microlens array formed by the optical system 41 is sometimes called the diffusion section 40.

[0074] The optical path of light passing through the diffusion section 40 will be described with reference to FIGS. First, the optical path when the diffusion unit 40 is viewed from the left and right will be described. As shown in FIG. 15 , light that is incident on the incident surface of the incident-side lens unit 42 substantially parallel to the main optical axis Mx and the optical axis Ax2 is refracted at the incident surface. A portion of the light refracted at the incident surface, light L1, is totally reflected at the second surface 44B of the cavity 44 and travels toward the exit-side lens unit 43. The other portion of the light refracted at the incident surface, light L2, travels directly toward the exit-side lens unit 43. The light that is incident on the exit-side lens unit 43 is refracted at the exit surface of the exit-side lens unit 43.

[0075] If light L1 is not reflected by second surface 44B, it may travel to an output-side lens portion of a different optical system that does not correspond to the input-side lens portion 42 into which light L1 is incident. In this case, the light that is refracted at the output surface of the output-side lens portion may not travel in the desired direction and may become a source of stray light. Because microlens array 7 according to this embodiment includes second surface 44B of cavity 44, it is possible to cause almost all of the light that enters input-side lens portion 42 to exit from the corresponding output-side lens portion 43, thereby reducing the occurrence of stray light and improving light utilization efficiency. Furthermore, the cut line forming portion formed by the boundary between the first surface 44A and the second surface 44B of the hollow portion 44 effectively blocks light that would otherwise be irradiated upward due to refraction at the emission surface of the emission-side lens portion 43 if it were not reflected by the second surface 44B. This makes it less likely that light will be irradiated upward in front of the vehicle lamp 1 and cause dazzle to oncoming vehicles.

[0076] Next, the optical path when the diffusion unit 40 is viewed from above and below will be described. As shown in Fig. 16, light that is incident on the incident surface of the incident-side lens unit 42 substantially parallel to the main optical axis Mx is refracted at the incident surface. The light refracted at the incident surface converges at the focal point of the incident-side lens unit 42, and then travels through the microlens array 7 so as to be diffused again. Light that is incident on the exit-side lens unit 43 is refracted at the exit surface. At this time, the light refracted at the exit surface travels so as to be further diffused.

[0077] In a microlens array such as that disclosed in Patent Document 1 (see also FIG. 18), the exit surface of the exit-side lens portion forms a convex curved surface when viewed from both the top and bottom and the left and right. In this case, as shown in FIG. 18, light emitted from the exit surface of the exit-side lens tends to be focused rather than diffused. When attempting to form a low-beam light distribution pattern with such a microlens array, the diffusion of light in the left and right directions tends to be insufficient.

[0078] In the microlens array 7 according to this embodiment, the exit surface of the exit-side lens section 43 of the optical system 41 constituting the diffusion section 40 is flat when viewed from the first direction, i.e., the up-down direction, and is curved when viewed from the second direction, i.e., the left-right direction. When viewed from the left and right, the exit surface of exit-side lens portion 43 of diffusion unit 40 is curved, so light emitted from diffusion unit 40 tends to be focused in the up and down directions. On the other hand, when viewed from the up and down directions, the exit surface of exit-side lens portion 43 of diffusion unit 40 is flat, so light emitted from diffusion unit 40 tends to be diffused in the left and right directions. The vehicular lamp 1 is required to have a wider illumination range in the left-right direction than in the up-down direction. The vehicular lamp 1 according to this embodiment can easily form a light distribution pattern with a wide illumination range in the left-right direction.

[0079] The microlens array 7 according to this embodiment may further include an optical system 51 that constitutes the light distribution forming section 50, in addition to the optical system 41 that constitutes the diffusion section 40. Fig. 17 is a cross-sectional view of the microlens array 7 having the light distribution forming section 50, viewed from the right. Fig. 18 is a cross-sectional view of the microlens array 7 having the light distribution forming section 50, viewed from above. The light distribution forming section 50 differs from the diffusion section 40 in that the exit surface of the exit-side lens forms a curved surface even when viewed from above and below.

[0080] The optical path of light passing through the light distribution formation section 50 will be described with reference to FIGS. The light path when the light distribution forming unit 50 is viewed from the left and right is the same as that of the diffusion unit 40. That is, the light emitted from the exit surface of the exit-side lens unit 53 travels in a generally downward direction while converging.

[0081] Next, the optical path when the light distribution forming unit 50 is viewed from above and below will be described. As shown in Fig. 18, light that is incident on the incident surface of the incident-side lens unit 52 substantially parallel to the main optical axis Mx is refracted at the incident surface. The light refracted at the incident surface converges at the focal point of the incident-side lens unit 52, and then travels through the microlens array 7 so as to diffuse again. Light that is incident on the exit-side lens unit 53 is refracted at the exit surface. However, unlike the optical path in the diffusion unit 40, the light refracted at the exit surface travels so as to converge.

[0082] The optical systems 41, 51 of the microlens array 7 according to this embodiment can also constitute the light distribution forming section 50 in addition to the diffusion section 40. The light distribution forming section 50 is likely to form a concentrated light distribution pattern. The microlens array 7 can both irradiate light widely by the diffusion section 40 and irradiate light concentrated by the light distribution forming section 50.

[0083] 17 and 18, the incident-side lens sections 42, 52 of the diffusion section 40 and the light distribution forming section 50 may be biconic lenses having two different radii of curvature on the incident surface. In this case, the radii of curvature are different when the incident-side lens sections 42, 52 are viewed from the left and right direction and when viewed from the top and bottom direction.

[0084] Here, it is desirable that the radii of curvature of the incident surfaces of incident-side lens portions 42, 52 are different when diffusing portion 40 and light distribution forming portion 50 are viewed from above and below. Comparing Figures 16 and 18, the radius of curvature of the incident surface of incident-side lens portion 42 of diffusion portion 40 is smaller than the radius of curvature of the incident surface of incident-side lens portion 52 of light distribution forming portion 50.

[0085] Because the radius of curvature of the incident surface of incident-side lens portion 42 of diffusion portion 40 is smaller than the radius of curvature of the incident surface of incident-side lens portion 52 of light distribution forming portion 50, the focal length of incident-side lens portion 42 of diffusion portion 40 is shorter than the focal length of incident-side lens portion 52 of light distribution forming portion 50. As a result, light passing through diffusion portion 40 is more diffused.

[0086] Fig. 19 is a front view (front side view) of the output-side lens portions 43, 53 of the multiple optical systems 41, 51 that make up the microlens array 7. As shown in Fig. 19, the diffusion portion 40 is surrounded by the light distribution forming portion 50. With this configuration, a microlens array 7 with excellent design can be realized.

[0087] The vehicle lamp 1 according to this embodiment includes the above-described microlens array 7 in addition to the light source 5 and the primary lens 6. This makes it possible to realize a vehicle lamp 1 that can emit more diffused light.

[0088] In the vehicle lamp 1 according to this embodiment, the light source that irradiates light onto the diffusion section 40 and the light distribution forming section 50 may be configured separately. FIG. 20 is a cross-sectional view of the vehicle lamp 1 as viewed from above. In addition to the microlens array 7 that includes the diffusion section 40 and the light distribution forming section 50, the lamp chamber 4 is equipped with a first light source 5A, a second light source 5B, a first primary lens 6A, and a second primary lens 6B. Light emitted from the first light source 5A is incident on the light distribution forming section 50 via the first primary lens 6A. Light emitted from the second light source 5B is incident on the diffusion section 40 via the second primary lens 6B.

[0089] In such a vehicle lamp 1, light emitted from the first light source 5A passes through the first primary lens 6A and enters the light distribution forming section 50, and light emitted from the second light source 5B passes through the second primary lens 6B and enters the diffusion section 40. Since the light source and primary lens are provided independently in the light distribution forming section 50 and the diffusion section 40, the design of the vehicle lamp 1 is optically easy.

[0090] Although the above example illustrates a vehicle lamp that has separate light sources that irradiate light to the diffusion section 40 and the light distribution forming section 50, the vehicle lamp may also be configured to irradiate light from a single light source toward a microlens array that includes a diffusion section and a light distribution forming section.

[0091] 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.

[0092] The microlens array 7 of the present disclosure is preferably used in vehicle lamps, but may also be used in lamps for other purposes.

[0093] This application is based on Japanese Patent Application No. 2021-139973 filed on August 30, 2021, Japanese Patent Application No. 2021-139974 filed on August 30, 2021, and Japanese Patent Application No. 2021-139975 filed on August 30, 2021, the contents of which are incorporated herein by reference.

Claims

1. A microlens array having a plurality of optical systems, Each of the optical systems includes a pair of an incident-side lens unit and an exit-side lens unit, a low refractive index portion is provided between the incident surface of the incident-side lens portion and the exit surface of the exit-side lens portion, The refractive index of the low refractive index portion is lower than the refractive index of the other portions, the low refractive index portion includes a first surface extending through a focal point of the exit surface and a second surface extending from the first surface to the entrance surface; a cut line forming portion is formed by a boundary portion between the first surface and the second surface, When viewed from the front of the incident-side lens portion, the incident surface is provided at a position that does not overlap with the second surface, In at least one of the optical systems, the exit surface of the exit-side lens portion is divided into a first region and a second region, the first region has a radius of curvature at which a focus is located in the cut line forming portion, The second region has a radius of curvature that is greater than the radius of curvature of the first region. Microlens array.

2. The microlens array according to claim 1 , wherein the low refractive index portion is a cavity portion.

3. The microlens array according to claim 1 , wherein the incident surface is located on the opposite side of the optical axis of the exit-side lens portion from the low-refractive-index portion.

4. The microlens array according to claim 1 , wherein the optical axis of the exit-side lens portion passes through a boundary line between the first region and the second region.

5. 2. The microlens array according to claim 1, wherein the radius of curvature of the second region is 1.1 to 1.5 times the radius of curvature of the first region.

6. A light source and The microlens array according to claim 1; A vehicle lighting fixture comprising:

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