Lens sheet and light source module

Abstract

The present invention provides a lens sheet in which different optical properties are imparted at multiple locations within the plane. [Solution] The lens sheet 30 includes a first surface 31 and a second surface 32 facing a first direction D1. At least one of the first surface and the second surface includes a lens surface 40. At least one of the first surface and the second surface includes a plurality of diffusion elements 50. At least one of the shape and density of the plurality of diffusion elements, the direction in which maximum brightness is obtained in the brightness angular distribution on the second surface when parallel light parallel to the first direction is incident on the first surface, and the full width at half maximum in the brightness angular distribution differ among a plurality of positions in a plane perpendicular to the first direction.

Description

Technical Field

[0001] The present disclosure relates to a lens sheet and a light source module.

Background Art

[0002] Patent Document 1 discloses a lens sheet. The lens sheet adjusts the optical path of incident light. The lens sheet adjusts the optical path by refraction. The incident light can pass through the lens sheet and proceed in a direction non-parallel to the incident direction to the lens sheet. The lens sheet disclosed in Patent Document 1 also has a diffusion function. The lens sheet described in Patent Document 1 has a function of adjusting the optical path of incident light and a function of diffusing incident light.

[0003] The optical sheet disclosed in Patent Document 2 has different optical characteristics in each region in the plane. The optical sheet disclosed in Patent Document 2 directs the light emitted from each region toward the user respectively. The optical sheet disclosed in Patent Document 2 is suitable for applications that direct light to a predetermined relative position with respect to the optical sheet. The optical path adjustment function in the optical sheet can improve the utilization efficiency of light. As an example, the optical sheet disclosed in Patent Document 2 is suitable for applications where a device such as an optical sensor is located at a predetermined relative position with respect to the optical sheet, and applications where an observer is located at a predetermined relative position with respect to the optical sheet.

[0004] The devices disclosed in Patent Document 1 and Patent Document 2 include a plurality of optical sheets. By combining a plurality of optical sheets having different optical characteristics, the device can achieve desired optical characteristics.

[0005] The application range of the device including the lens sheet is expanding. The device including the lens sheet is also applied to in-vehicle display devices, wearable display devices, and the like. Along with this trend, the optical specifications required for the device including the lens sheet are becoming more complicated. For example, it is convenient if the lens sheet can be given different optical characteristics at a plurality of positions in the plane.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Patent No. 4779893 [Patent Document 2] Patent No. 6008241 [Overview of the project] [Problems that the invention aims to solve]

[0007] This disclosure aims to impart different optical properties to a lens sheet at multiple locations within its surface. [Means for solving the problem]

[0008] A lens sheet according to one embodiment of this disclosure is It comprises a first surface and a second surface facing each other in a first direction, At least one of the first and second surfaces includes a lens surface, At least one of the first and second surfaces includes a plurality of diffusion elements, At least one of the shapes and densities of the plurality of diffusion elements, the direction in which maximum brightness is obtained in the brightness angular distribution on the second surface when parallel light parallel to the first direction is incident on the first surface, and the full width at half maximum in the brightness angular distribution differ among a plurality of positions in a plane perpendicular to the first direction. [Effects of the Invention]

[0009] According to this disclosure, different optical properties can be imparted to a lens sheet at multiple locations within its surface. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a diagram illustrating one embodiment of the present disclosure, and shows a light source module as an example of a device to which a lens sheet is applied. [Figure 2] Figure 2 is a cross-sectional view showing an example of a lens sheet. [Figure 3] FIG. 3 is a cross-sectional view showing another example of the lens sheet. [Figure 4] FIG. 4 is a cross-sectional view showing yet another example of the lens sheet. [Figure 5] FIG. 5 is a cross-sectional view showing yet another example of the lens sheet. [Figure 6] FIG. 6 is a cross-sectional view showing yet another example of the lens sheet. [Figure 7] FIG. 7 is a cross-sectional view showing yet another example of the lens sheet. [Figure 8] FIG. 8 is a plan view showing an example of the arrangement of a plurality of lens elements included in the lens sheet shown in FIG. 7. [Figure 9] FIG. 9 is a plan view showing another example of the arrangement of a plurality of lens elements included in the lens sheet shown in FIG. 7. [Figure 10A] FIG. 10A is a cross-sectional view showing an example of a plurality of diffusion elements included in the lens sheet. [Figure 10B] FIG. 10B is a cross-sectional view showing another example of a plurality of diffusion elements included in the lens sheet. [Figure 10C] FIG. 10C is a cross-sectional view showing yet another example of a plurality of diffusion elements included in the lens sheet. [Figure 11A] FIG. 11A is a cross-sectional view showing yet another example of a plurality of diffusion elements included in the lens sheet. [Figure 11B] FIG. 11B is a cross-sectional view showing yet another example of a plurality of diffusion elements included in the lens sheet. [Figure 12] FIG. 12 is a cross-sectional view showing yet another example of a plurality of diffusion elements included in the lens sheet. [Figure 13] FIG. 13 is a graph showing an example of the luminance angular distribution on the second surface in a state where parallel light parallel to the first direction is incident on the first surface. [Figure 14] FIG. 14 is a graph showing another example of the luminance angular distribution on the second surface in a state where parallel light parallel to the first direction is incident on the first surface. [Figure 15]FIG. 15 is a diagram for explaining the operation of a lens sheet and an apparatus including the lens sheet.

Embodiment for Carrying out the Invention

[0011] One embodiment of the present disclosure relates to the following <1> to <10>.

[0012] <1> Comprising a first surface and a second surface facing each other in a first direction, At least one of the first surface and the second surface includes a lens surface, At least one of the first surface and the second surface includes a plurality of diffusion elements, A lens sheet in which at least one of the shape and density of the plurality of diffusion elements, the direction in which the maximum luminance is obtained in the luminance angle distribution on the second surface in a state where parallel light parallel to the first direction is incident on the first surface, and the full width at half maximum in the luminance angle distribution are different among a plurality of positions in a plane orthogonal to the first direction.

[0013] <2> One of the first surface and the second surface includes the lens surface, The lens sheet according to <1>, wherein the other of the first surface and the second surface includes the plurality of diffusion elements.

[0014] <3> The lens sheet according to or <2>, wherein one of the first surface and the second surface includes both the lens surface and the plurality of diffusion elements.

[0015] <4> Comprising a plurality of lens elements including the lens surface, The plurality of lens elements are arranged in a second direction non-parallel to the first direction, Each of the plurality of lens elements linearly extends in a direction non-parallel to the first direction and the second direction. The lens sheet according to any one of <1> to <3>.

[0016] <5> The lens comprises a plurality of lens elements including the aforementioned lens surface, The aforementioned plurality of lens elements are arranged in a concentric circle. <1> ~ <3> A lens sheet as described in any one of the items.

[0017] <6> The width of each lens element along the arrangement direction of the plurality of lens elements is greater than the width of the light-diffusing element located in the same region as the lens element in a plane perpendicular to the first direction. <4> or <5> The lens sheet as described.

[0018] <7> The Fresnel lens comprises a plurality of lens element surfaces constituting the lens surface, and rise surfaces arranged alternately with each of the plurality of lens element surfaces. <1> ~ <5> A lens sheet as described in any one of the items.

[0019] <8> The width of each lens element surface along the arrangement direction of the plurality of lens element surfaces is greater than the width of the light diffusing element located in the same region as the lens element surface in a plane perpendicular to the first direction. <7> The lens sheet as described.

[0020] <9> A light source device including a light-emitting surface, <1> ~ <8> A lens sheet as described in any one of the items, A light source module in which the lens sheet is superimposed on the light source device in the first direction such that the first surface and the light-emitting surface face each other in the first direction.

[0021] <10> In the state in which light is emitted from the light-emitting surface, the standard deviation of the maximum brightness at each position on the second surface of the lens sheet is smaller than the standard deviation of the maximum brightness at each position on the light-emitting surface. <9> The light source module described.

[0022] This embodiment will be described below with reference to the drawings. In the drawings attached to this specification, the scale and aspect ratios may be changed from those of the actual object as appropriate for ease of understanding. In the cross-sectional views, hatching may be omitted for ease of understanding. Configurations shown in some drawings may be omitted in other drawings.

[0023] In this specification, terms such as "parallel," "orthogonal," and "identical," as well as values ​​of length and angle, which specify shapes, geometric conditions, and their degrees, are not limited to their strict meanings but are interpreted to include a range of values ​​to which similar functions can be expected.

[0024] In this specification, terms such as "sheet," "film," and "plate" are not distinguished from each other solely on the basis of name differences. For example, "lens sheet" is not distinguished solely from components called lens film or lens plate solely on the basis of name differences. "Optical sheet" is not distinguished solely from components called optical film or optical plate solely on the basis of name differences.

[0025] In this specification, the normal direction of a sheet-like (film-like, plate-like) member means the direction parallel to the normal or perpendicular to the sheet surface of the sheet-like (film-like, plate-like) member in question. The "sheet surface (film surface, plate surface)" means the surface that coincides with the sheet-like (film-like, plate-like) member in question when the sheet-like (film-like, plate-like) member in question is observed as a whole.

[0026] In this specification, if multiple upper limit candidates and multiple lower limit candidates are given for a certain parameter, the numerical range of that parameter may be constructed by combining any one upper limit candidate and any one lower limit candidate. As an example, consider the statement, "Parameter B may be A1 or greater, A2 or greater, A3 or greater. Parameter B may be A4 or less, A5 or less, A6 or less." In this example, the numerical range of parameter B may be A1 or greater and A4 or less, A1 or greater and A5 or less, A1 or greater and A6 or less, A2 or greater and A4 or less, A2 or greater and A5 or less, A2 or greater and A6 or less, A3 or greater and A4 or less, A3 or greater and A5 or less, and A3 or greater and A6 or less.

[0027] To clarify directional relationships between drawings, some drawings use arrows with common symbols to indicate the first direction D1, the second direction D2, and the third direction D3 as common directions. The tip of the arrow is the first side of each direction. The opposite side of the arrow is the second side of each direction. For example, as shown in Figure 2, the symbol of a dot inside a circle indicates an arrow pointing from the drawing plane towards the viewer, in a direction perpendicular to the drawing plane.

[0028] Figures 1 to 15 are diagrams illustrating the lens sheet according to this embodiment. Figure 1 shows an example of application of the lens sheet according to this embodiment. In the example shown in Figure 1, the lens sheet is applied to a light source module. This embodiment will be described below with reference to the illustrated specific example.

[0029] As shown in Figure 1, the light source module 10 includes a light source device 20 and a lens sheet 30. The light source device 20 may include a light-emitting surface 21. The light source device 20 is not particularly limited.

[0030] The light source device 20 may be a surface light source device that emits planar light. The light source device 20 may be an edge-lit surface light source device. The edge-lit surface light source device may include a light guide plate and a light-emitting element positioned facing the light guide plate. The light source device 20 may be a direct-lit surface light source device. The direct-lit surface light source device may include an optical sheet and a light-emitting element facing the optical sheet in a first direction. The optical sheet included in the direct-lit light source device may be one or more of a light-diffusing sheet, a light-concentrating sheet, a prism sheet, and a lens sheet.

[0031] The light source device 20 may also be a display element. The light source device 20 may also be a liquid crystal display element. In this example, the light source module 10 may also be a liquid crystal display device. The light source device 20 may also be an EL display element. In this example, the light source module 10 may also be an EL display device.

[0032] As shown in Figure 1, the light source module 10 may include a light source device 20 and an optical element 28. The optical element 28 adjusts the optical path of the light emitted from the light source device 20. The optical path adjustment function of the optical element 28 gives the light source module 10 the desired optical characteristics.

[0033] The light source device 20 and the optical element 28 are stacked in the first direction D1. The optical element 28 faces the light-emitting surface 21 in the first direction D1.

[0034] The optical component 28 includes a lens sheet 30. In the example shown in Figure 1, the optical component 28 includes only one lens sheet 30. That is, the optical component 28 consists of a lens sheet 30. The optical component 28 is not limited to the illustrated example and may include optical sheets superimposed on the lens sheet 30. Note that the lens sheet 30 is just one example of an optical sheet. Examples of optical sheets include light-gathering sheets such as prism sheets and light-diffusing sheets with light-diffusing functions. Multiple optical sheets included in the optical component 28 are superimposed in a first direction D1. The first direction D1 is the stacking direction.

[0035] In the illustrated example, the light-emitting surface 21 is a plane perpendicular to the first direction D1. The lens sheet 30 extends on a plane perpendicular to the first direction D1. The first direction D1 is the thickness direction. The light-emitting surface 21 and the lens sheet 30 are parallel to the second direction D2 and the third direction D3. In the illustrated example, the second direction D2 and the third direction D3 are perpendicular to each other. In the illustrated example, the second direction D2 is perpendicular to the first direction D1, and the third direction D3 is perpendicular to the first direction D1. Unlike the illustrated example, the light-emitting surface 21 and the lens sheet 30 may extend on a curved surface.

[0036] Figures 2 to 7 show several specific examples of the lens sheet 30 according to this embodiment. The lens sheet 30 shown in Figures 2 to 7 can be applied to the light source module 10 shown in Figure 1.

[0037] As shown in Figures 2 to 12, the lens sheet 30 may include a first surface 31 and a second surface 32. The first surface 31 and the second surface 32 face the first direction D1. The lens sheet 30 is in the form of a sheet. The first surface 31 and the second surface 32 may constitute a pair of main surfaces of the lens sheet 30.

[0038] In the illustrated example, the first surface 31 is closer to the light source device 20 than the second surface 32 in the first direction D1. The second surface 32 is further away from the light source device 20 than the first surface 31 in the first direction D1. The light-emitting surface 21, the first surface 31, and the second surface 32 are positioned in this order in the first direction D1. The lens sheet 30 is superimposed on the light source device 20 in the first direction D1 such that the first surface 31 and the light-emitting surface 21 face the first direction D1. In the lens sheet 30, the first surface 31 is the incident surface of light emitted from the light source device 20. The second surface 32 is the exit surface of light emitted from the light source device 20 and transmitted through the lens sheet 30.

[0039] At least one of the first surface 31 and the second surface 32 includes a lens surface 40. As used herein, the term "lens surface" is not limited to a lens surface in the narrow sense, but means a surface that bends the direction of light propagation by refraction. A lens surface in the narrow sense is a surface that has a lens function to focus parallel light at a focal point.

[0040] The configuration of the lens surface 40 is not particularly limited. The lens surface 40 may be a convex lens, as shown in the illustrated example. A lens surface 40 composed of a convex lens has a light-gathering function for incident light. The lens surface 40 may be a concave lens, as shown in the illustrated example. A lens surface 40 composed of a concave lens has a light-gathering or light-diffusing function for incident light.

[0041] The lens surface 40 may be a spherical lens. The lens surface 40 may be a lens that follows a portion of a sphere. The lens surface 40 may be a columnar lens. The lens surface 40 may be a lens that follows a portion of the side surface of a cylinder.

[0042] As shown in Figures 4 and 6, the first surface 31 may include the lens surface 40. As shown in Figures 2, 3, 5, 6, and 7, the second surface 32 may include the lens surface 40. As shown in Figure 6, both the first surface 31 and the second surface 32 may include the lens surface 40.

[0043] In the examples shown in Figures 4 and 6, the lens surface 40 constitutes the entire area of ​​the first surface 31. In the examples shown in Figures 2, 3, 5, and 6, the lens surface 40 constitutes the entire area of ​​the second surface 32. The lens surface 40 may constitute only a portion of the first surface 31. The lens surface 40 may constitute only a portion of the second surface 32.

[0044] As shown in Figure 7, the lens sheet 30 may include a plurality of lens elements 45. Each of the plurality of lens elements 45 includes a lens element surface 41. The lens element surface 41 constitutes the lens surface 40. In a lens sheet 30 including a plurality of lens elements 45, the lens surface 40 includes a plurality of lens element surfaces 41. By dividing the lens surface 40 into a plurality of lens element surfaces 41, the dimension of the lens sheet 30 including the lens surface 40 along the first direction D1 can be shortened. In particular, the lens sheet 30 including a lens surface 40 that is greatly inclined with respect to a plane perpendicular to the first direction D1 can be made thinner.

[0045] As shown in Figure 8, the multiple lens elements 45 may be arranged in an arrangement direction nonparallel to the first direction D1. Each lens element 45 may extend linearly in a direction nonparallel to both the first direction D1 and the arrangement direction. That is, the multiple lens elements 45 may be linearly arranged. In the example shown in Figure 8, the multiple lens elements 45 are arranged in a second direction D2 perpendicular to the first direction D1. In the example shown in Figure 8, each lens element 45 extends linearly in a third direction D3 perpendicular to both the first direction D1 and the second direction D2.

[0046] As shown in Figure 9, the multiple lens elements 45 may be arranged concentrically. In other words, the multiple lens elements 45 may be arranged to lie on multiple concentric circles. Each of the multiple lens elements 45 arranged concentrically extends along a circumference of a circle of different diameters centered on a common central axis. The central axis is parallel to the first direction D1. The direction of arrangement of the multiple lens elements 45 arranged concentrically is the radial direction perpendicular to the central axis.

[0047] In the examples shown in Figures 7 to 9, the multiple lens elements 45 may constitute a Fresnel lens 47. In the examples shown in Figures 7 to 9, the lens sheet 30 may include the Fresnel lens 47. The lens elements 45 include a lens element surface 41 and a rise surface 43. In the Fresnel lens 47, certain optical functions can be expected from the combination of the multiple lens element surfaces 41 included in the multiple lens elements 45. As an example, a lens sheet 30 is configured to have a convex lens function or a concave lens function.

[0048] In the example shown in Figure 8, the multiple lens elements 45 constitute a linear Fresnel lens. The lens sheet 30 shown in Figure 8 includes a linear Fresnel lens. In the example shown in Figure 9, the multiple lens elements 45 constitute a circular Fresnel lens. The lens sheet 30 shown in Figure 9 includes a circular Fresnel lens.

[0049] The rise surface 43 connects two adjacent lens element surfaces 41 in the arrangement direction. The rise surface 43 is a surface that is not expected to have any optical effect. The rise surface 43 may be parallel to the first direction D1, and may or may not be significantly inclined with respect to the first direction D1.

[0050] In the examples shown in Figures 2 to 7, the lens surface 40 may be formed by embossing. The embossed lens surface 40 is obtained by heating a substrate containing a thermoplastic resin and pressing an embossing die onto it.

[0051] The lens surface 40 may be formed as a resin molding layer. A curable resin composition is used to form the resin molding layer. The curable resin composition may be applied to a substrate. By curing the coating film of the curable resin composition while pressing a mold onto it, the lens surface 40 as a resin molding layer is obtained. In this example, the lens sheet 30 may include a first layer 36 as a substrate and a second layer 37 as a resin molding layer, as shown in Figure 5.

[0052] The first layer 36 may include a resin film. The first layer 36 may include glass. The resin film included in the first layer 36 may be a uniaxially oriented or biaxially oriented polyethylene terephthalate film. The second layer 37 may include a cured product of a thermosetting resin composition. The second layer 37 may include a cured product of an ionizing radiation-curable resin composition. The second layer 37 may include a cured product of an ultraviolet-curable resin composition.

[0053] At least one of the first surface 31 and the second surface 32 includes a plurality of diffusion elements 50. The diffusion elements 50 have the function of diffusing incident light. The diffusion elements 50 may also diffuse transmitted light. The diffusion elements 50 may diffuse incident light by one or more of the following: refraction, reflection, and diffraction. Diffusion in the diffusion elements 50 may be isotropic diffusion or anisotropic diffusion.

[0054] As shown in Figures 3, 5, 6, and 7, the first surface 31 may include the diffusion element 50. As shown in Figures 2, 4, 5, and 6, the second surface 32 may include the diffusion element 50. As shown in Figures 5 and 6, both the first surface 31 and the second surface 32 may include the diffusion element 50.

[0055] The diffusion elements 50 included in the first surface 31 or the second surface 32 have a diffusion function by surface diffusion. By making the light diffusion by the diffusion elements 50 surface diffusion, stray light can be reduced. By reducing stray light, the transmittance of the lens sheet 30 can be improved.

[0056] The diffusion elements 50 may be uneven elements such as individual recesses or protrusions formed on the surface of the lens sheet 30. The diffusion elements 50 may be linear or point-shaped. Multiple linear diffusion elements 50 may be arranged linearly. Multiple point-shaped diffusion elements 50 may be arranged two-dimensionally. A two-dimensional arrangement of diffusion elements 50 means that the diffusion elements 50 are arranged in at least two directions that are not parallel to each other. That is, the two-dimensional arrangement of diffusion elements 50 causes the diffusion elements 50 to be dispersed in a plane. Multiple diffusion elements 50 may be arranged regularly. The diffusion elements 50 may be arranged irregularly.

[0057] The configuration of the diffusion element 50 is not particularly limited. Multiple diffusion elements 50 may have the same configuration as each other, or they may have different configurations as each other.

[0058] The cross-sectional shape of the diffusion element 50 in a cross-section perpendicular to the first direction D1 is not particularly limited. Multiple diffusion elements 50 may have the same cross-sectional shape as each other, or they may have different cross-sectional shapes as each other. As shown in Figures 10A to 11B, the cross-sectional shape of the diffusion element 50 in a cross-section perpendicular to the first direction D1 may have a shape corresponding to a part of a circle. The cross-sectional shape of the diffusion element 50 may be a semicircle. The cross-sectional shape of the diffusion element 50 may have a shape corresponding to a part of an ellipse. The cross-sectional shape of the diffusion element 50 may be a triangle, a quadrilateral, or a polygon with pentagons or more.

[0059] In the examples shown in Figures 2 to 7, the diffusion element 50 may be formed by embossing. The diffusion element 50 is obtained by embossing by heating a substrate containing a thermoplastic resin and pressing an embossing mold onto it.

[0060] The diffusion element 50 may be formed as a resin molding layer. The resin molding layer can be made using a curable resin composition. The curable resin composition is applied, for example, to a substrate. The diffusion element 50 as a resin molding layer is obtained by curing the coating film while pressing a mold onto the coating film of the curable resin composition. In this example, the lens sheet 30 may include a first layer 36 as a substrate and a third layer 38 containing the diffusion element 50 as a resin molding layer, as shown in Figure 5.

[0061] The first layer 36 may include a resin film. The first layer 36 may include glass. The resin film included in the first layer 36 may be a uniaxially oriented or biaxially oriented polyethylene terephthalate film. The third layer 38 may include a cured product of a curable resin composition. The third layer 38 may include a cured product of a thermosetting resin composition. The third layer 38 may include a cured product of an ionizing radiation curable resin composition. The third layer 38 may include a cured product of an ultraviolet curable resin composition.

[0062] In the example shown in Figure 5, the lens sheet 30 includes a first layer 36, a second layer 37 constituting the second surface 32, and a third layer 38 constituting the first surface 31. The second layer 37 includes both the lens surface 40 and the diffusion element 50 as a resin molding layer. The mold used to manufacture the second layer 37 may have a shape complementary to both the lens surface 40 and the diffusion element 50, so that the lens surface 40 and the diffusion element 50 can be manufactured simultaneously.

[0063] In the example shown in Figure 12, the diffusion element 50 is configured as a protrusion caused by the particles 52. A protrusion caused by the particles 52 means a protrusion formed by the presence of the particles 52. As shown in Figure 12, the lens sheet 30 may include a surface layer 51 containing particles 52 and a binder component 53. The binder component 53 holds the particles 52. The particles 52 may be covered by the binder component 53. The particles 52 may be exposed from the binder component 53 to form a first surface 31 or a second surface 32. By making the thickness of the binder component 53 in the first direction D1 in the portion that does not hold the particles 52 smaller than the average particle diameter of the particles 52, a protrusion caused by the particles 52 can be formed.

[0064] In the example shown in Figure 12, the binder component 53 may be a resin. The binder component 53 may include a cured product of a curable resin composition. The binder component 53 may include a cured product of a thermosetting resin composition. The binder component 53 may include a cured product of an ionizing radiation-curable resin composition. The binder component 53 may include a cured product of an ultraviolet-curable resin composition.

[0065] The surface layer 51 shown in Figure 12 can be made using a resin composition containing a binder component 53 and particles 52. The surface layer 51 is obtained by solidifying or curing the coating of the resin composition. In this example, the resin composition is applied, for example, to a substrate. The resin composition may also be applied to a resin molding layer that forms irregularities corresponding to the lens surface 40. According to this example, the surface of the irregularity element 51 can constitute a first surface 31 or a second surface 32 including the diffusion element 50 and the lens surface 40.

[0066] As shown in Figures 3, 4, and 7, one of the first surface 31 and the second surface 32 may include a lens surface 40, and the other of the first surface 31 and the second surface 32 may include a plurality of diffusion elements 50. In the examples shown in Figures 3 and 7, the second surface 32 includes a lens surface 40, and the first surface 31 includes a plurality of diffusion elements 50. In the example shown in Figure 4, the first surface 31 includes a lens surface 40, and the second surface 32 includes a plurality of diffusion elements 50. By providing the lens surface 40 and the diffusion elements 50 on different surfaces 31 and 32, the optical design of the lens surface 40 and the diffusion elements 50 can be performed with a high degree of freedom. Therefore, complex optical properties can be imparted to each of the first surface 31 and the second surface 32.

[0067] As shown in Figure 2, one of the first surface 31 and the second surface 32 may include both the lens surface 40 and the multiple diffusion elements 50. In the example shown in Figure 2, the second surface 32 includes both the lens surface 40 and the multiple diffusion elements 50. The first surface 31 may also include both the lens surface 40 and the multiple diffusion elements 50. By providing the lens surface 40 and the diffusion elements 50 on only one of the first surface 31 and the second surface 32, the thickness of the lens sheet 30 can be reduced. Furthermore, since it is not necessary to impart optical functions to the other surface of the first surface 31 and the second surface 32, the other surface may be used for joining with other members. If optical functions are also imparted to the other surface of the first surface 31 and the second surface 32, the lens sheet 30 can be given more complex optical properties.

[0068] The lens surface 40 and the diffusion element 50 are of different sizes. Therefore, both the lens surface 40 and the diffusion element 50 can be mounted on the same surface. When the lens surface 40 and the diffusion element 50 are mounted on the same surface, they can fully perform their respective optical functions.

[0069] The minimum width of the diffusion element 50 along the direction perpendicular to the first direction D1 may be smaller than the minimum width of the lens surface 40 along the direction perpendicular to the first direction D1. The maximum width of the diffusion element 50 along the direction perpendicular to the first direction D1 may be smaller than the minimum width of the lens surface 40 along the direction perpendicular to the first direction D1. In the examples shown in Figures 7 to 9, the width of the diffusion element 50 along the arrangement direction of the multiple lens elements 45 may be smaller than the width of the lens elements 45 along the arrangement direction of the multiple lens elements 45. In the examples shown in Figures 7 to 9, the width of the diffusion element 50 along the arrangement direction of the multiple lens elements 45 may be smaller than the width of the lens element surface 41 along the arrangement direction of the multiple lens elements 45. The width of the diffusion element 50 may be smaller than the radius of curvature of the lens surface 40. With these configurations, the lens surface 40 and the diffusion element 50 can fully perform their respective optical functions even if they are arranged on the same surface.

[0070] The width of the diffusion element 50 along the direction perpendicular to the first direction D1 may be 0.1 μm or more, 1.0 μm or more, or 5.0 μm or more. The width of the diffusion element 50 along the direction perpendicular to the first direction D1 may be 1.0 mm or less, 100 μm or less, or 50 μm or less.

[0071] The width of the lens element 45 along the alignment direction of the multiple lens elements 45 may be 1.0 μm or more, 5.0 μm or more, or 10 μm or more. The width of the lens element 45 along the alignment direction of the multiple lens elements 45 may be 10 mm or less, 1.0 mm or less, or 100 μm or less.

[0072] The width of the lens element surface 41 along the alignment direction of the multiple lens elements 45 may be 1.0 μm or more, 5.0 μm or more, or 10 μm or more. The width of the lens element surface 41 along the alignment direction of the multiple lens elements 45 may be 10 mm or less, 1.0 mm or less, or 100 μm or less.

[0073] In the lens sheet 30 according to this embodiment, the following three evaluation items (A) to (C) are all different at multiple positions in a plane perpendicular to the first direction D1. (A): At least one of the shape and density of the multiple diffusion elements 50 (B): The direction in which the maximum brightness is obtained in the brightness angle distribution on the second surface when parallel light parallel to the first direction is incident on the first surface. (C): Full width at half maximum in the brightness angle distribution on the second surface when parallel light parallel to the first direction is incident on the first surface.

[0074] In other words, the lens sheet 30 includes at least two positions where all three evaluation items (A) to (C) are different. To put it another way, the evaluation items (A) to (C) evaluated at at least two evaluation positions are all different.

[0075] Furthermore, the three evaluation items (A) to (C) may differ among three positions in a plane perpendicular to the first direction D1, or among four positions in a plane perpendicular to the first direction D1, or among five positions in a plane perpendicular to the first direction D1.

[0076] The five positions may be determined as follows: Divide the straight line connecting the center of gravity of the lens sheet 30 and the point on the outer edge of the lens sheet 30 furthest from the center of gravity into five equal parts. The center positions of the straight line within each of the small parts of the lens sheet 30 may be the five positions for checking evaluation items (A) to (C).

[0077] Item (A) relates to the configuration of the multiple diffusion elements 50 of the lens sheet 30. Both the shape and density of the diffusion elements 50 affect the degree of light diffusion performance of the lens sheet 30 due to the multiple diffusion elements 50. At multiple locations where item (A) is different, the lens sheet 30 has different degrees of light diffusion performance. That is, the light diffusion performance of the lens sheet 30 is not constant in the plane perpendicular to the first direction D1.

[0078] Figures 10A and 10C show diffusion elements 50 with different shapes. More specifically, Figures 10A and 10B show diffusion elements 50 with different aspect ratios. The aspect ratio is the ratio (H / W) of the height of the diffusion element 50 to the width W of the diffusion element 50 in a cross section parallel to the first direction D1. By increasing the aspect ratio, the light diffusion performance of the lens sheet 30 due to multiple diffusion elements 50 can be enhanced.

[0079] The cross-sectional shape of the diffusion element 50 shown in Figures 10A and 10C is semicircular. The diffusion element 50 shown in Figure 10B has the base end removed from the diffusion element 50 shown in Figures 10A and 10C. The cross-sectional shape of the diffusion element 50 shown in Figure 10B corresponds to a part of a semicircle. The aspect ratio of the diffusion element 50 shown in Figure 10B is larger than the aspect ratio of the diffusion element 50 shown in Figures 10A and 10C. The light diffusion performance of the lens sheet 30 due to the diffusion element 50 shown in Figure 10B is weaker than the light diffusion performance of the lens sheet 30 due to the diffusion element 50 shown in Figures 10A and 10C.

[0080] Figures 10A and 10C show diffusion elements 50 having different dimensions. However, the cross-sectional shapes of the diffusion element 50 shown in Figure 10A and the diffusion element 50 shown in Figure 10C are similar. Therefore, the light diffusion performance due to refraction of the diffusion element 50 shown in Figure 10A is about the same as the light diffusion performance due to tropism of the diffusion element 50 shown in Figure 10C. However, in the lens sheet 30 using the smaller of the two similarly shaped diffusion elements 50, the diffraction phenomenon is promoted. That is, in the lens sheet 30 using the smaller diffusion element 50, the diffraction efficiency is higher and the diffraction angle is also larger. The light diffusion performance of the lens sheet 30 due to the diffusion element 50 shown in Figure 10C is stronger than the light diffusion performance of the lens sheet 30 due to the diffusion element 50 shown in Figure 10A.

[0081] Figures 11A and 11B show lens sheets 30 containing diffusion elements 50 at different densities. The diffusion elements 50 shown in Figure 11A have the same shape as the diffusion elements 50 shown in Figure 11B. The pitch of the diffusion elements 50 shown in Figure 11A is longer than the pitch of the diffusion elements 50 shown in Figure 11B. The density of the multiple diffusion elements 50 shown in Figure 11A is smaller than the density of the multiple diffusion elements 50 shown in Figure 11B. The light diffusion performance of the lens sheet 30 due to the diffusion elements 50 shown in Figure 11A is weaker than the light diffusion performance of the lens sheet 30 due to the diffusion elements 50 shown in Figure 11B.

[0082] The determination of whether item (A) differs among multiple positions in the plane perpendicular to the first direction D1 of the lens sheet 30 is carried out as follows.

[0083] At each position, a square region is identified as the evaluation region on the surface (first or second surface) on which multiple diffusion elements are provided. The length of one side of the evaluation region shall be 1 / 100 or less of the longest length of the straight line connecting two points on the outer edge of the lens sheet 30 to be evaluated. The length of one side of the evaluation region shall be 1 / 100 of the longest length of the straight line connecting two points on the outer edge of the lens sheet 30 to be evaluated, except in the cases described below. When the diffusion element 50 is provided on the lens surface 40, the length of one side of the evaluation region shall be the maximum length within the evaluation region in which the angle of the lens surface 40 with respect to the first direction D1 is substantially the same. Here, substantially the same means that the direction in which the maximum brightness is obtained in the brightness angle distribution when parallel light is incident does not change by 1° or more. The maximum brightness is measured in the same manner as the maximum brightness in feature (B) described below. When the diffusion element 50 is provided on the lens surface 40 and the lens surface 40 is divided, the length of one side of the evaluation region shall be the maximum length in which the evaluation region can be included in one of the divided lens surfaces 40. As a specific example, if the lens surface 40 includes multiple lens element surfaces 41, the length of one side of the evaluation area is set to the maximum length that the evaluation area can be contained within a single lens element surface 41.

[0084] The surface shape (profile) of the evaluation area at each position on a surface with multiple diffusion elements is measured using a 3D measuring device. The "shape of the multiple diffusion elements" is evaluated as identical if the surface shape along one direction is identical and the surface shape along the other direction perpendicular to that direction is identical between the evaluation areas at two positions; otherwise, the "shape of the multiple diffusion elements" is evaluated as different. The "density of the multiple diffusion elements" is evaluated as identical if the RSm along one direction is identical and the RSm along the other direction perpendicular to that direction is identical between the evaluation areas at two positions; otherwise, the "density of the multiple diffusion elements" is evaluated as different. This is the average length of the roughness curve elements as defined in JIS B0601:2013.

[0085] Items (B) and (C) relate to optical properties identified from the luminance angle distribution. The luminance angle distribution is based on the luminance on the second surface 32, measured when parallel light parallel to the first direction D1 is incident on the first surface 31 of the lens sheet 30. The luminance at the measurement position in the plane perpendicular to the first direction D1 is measured in all directions. The luminance angle distribution is measured on a plane parallel to both the first direction D1 and the second direction D2, a plane parallel to both the first direction D1 and the third direction D3, and 17 planes parallel to both the first direction D1 and each direction inclined by 5° from the second direction D2 to the third direction D3. On each plane, the luminance is measured for the first direction D1 and for each direction inclined by 5° on both sides from the first direction D1.

[0086] Item (B), "Maximum Brightness," refers to the highest brightness measured at a single measurement location. The unit of brightness is cd / m². 2 "

[0087] The "full width at half maximum" in item (C) refers to the full width at half maximum of the luminance angular distribution in each direction within the plane where the maximum luminance was measured. Full width at half maximum means the angular range in which a luminance of half or more of the maximum luminance in that luminance angular distribution can be obtained. If the maximum luminance is obtained in the first direction, it is the maximum value among the full widths at half maximum of the luminance angular distribution in each direction within all planes where luminance was measured. The unit of full width at half maximum is "°".

[0088] For measuring luminance in the luminance angular distribution, the EZ Contrast XL80 from ELDIM Corporation may be used.

[0089] Here, Figures 13 and 14 are graphs showing the luminance angle distribution measured at two positions on the second surface 32 of the same lens sheet 30. In the luminance angle distribution at the first position shown in Figure 13, the direction in which maximum luminance was obtained was parallel to the first direction D1. In the luminance angle distribution at the first position shown in Figure 13, the full width at half maximum FW was 40°. In the luminance angle distribution at the second position shown in Figure 14, the direction in which maximum luminance was obtained was tilted at 39° with respect to the first direction D1. In the luminance angle distribution at the second position shown in Figure 14, the full width at half maximum FW was 28°. In the examples shown in Figures 13 and 14, the direction in which maximum luminance was obtained and the full width at half maximum in the luminance angle distribution differed between the first and second positions in the plane perpendicular to the first direction D1.

[0090] Next, the operation of the light source module 10 and lens sheet 30 will be explained with reference to the example shown in Figure 15.

[0091] In the example shown in Figure 15, the light source module 10 is positioned facing the sensor 60 in the first direction D1. The sensor 60 receives light emitted from the light source module 10. The width of the sensor 60 along the second direction D2 is smaller than the width of the light source module 10 along the second direction D2. The sensor 60 faces the central region of the light source module 10 in the second direction D2 and the first direction D1.

[0092] In the example shown in Figure 15, the light source module 10 includes a light source device 20 and an optical member 28. The light source device 20 may be a surface light source device. The optical member 28 includes a lens sheet 30. When parallel light along the first direction D1 is incident on the first surface 31, the lens sheet 30 has the brightness angle distribution shown in Figure 13 at the central position PD2C in the second direction D2 on the second surface. When parallel light along the first direction D1 is incident on the first surface 31, the lens sheet 30 has the brightness angle distribution shown in Figure 14 at the left end position PD2L in the second direction D2 on the second surface. When parallel light along the first direction D1 is incident on the first surface 31, the lens sheet 30 has a brightness angle distribution at the right end position PD2R in the second direction D2 on the second surface that is symmetrical to the brightness angle distribution shown in Figure 14.

[0093] The luminance angle distributions shown in Figures 13 and 14 are luminance angle distributions measured on a plane parallel to both the first direction D1 and the second direction D2. An angle tilted towards the first side (left side in the figure) from the first direction D1 to the second direction D2 is defined as a negative value, and an angle tilted towards the second side (left side in the figure) from the first direction D1 to the second direction D2 is defined as a positive value.

[0094] As shown in Figure 15, the light that passes through the lens sheet 30 at the leftmost position PD2L travels in the second direction D2, which is tilted to the right in Figure 15. In other words, most of the light that passes through the lens sheet 30 at the leftmost position PD2L travels towards the sensor 60.

[0095] As shown in Figure 15, the light that passes through the lens sheet 30 at the central position PD2C travels in the first direction D1. That is, most of the light that passes through the lens sheet 30 at the central position PD2C travels towards the sensor 60.

[0096] As shown in Figure 15, the light that passes through the lens sheet 30 at the rightmost position PD2R travels in the direction of the first side in the second direction D2, that is, inclined to the left in Figure 15. In other words, most of the light that passes through the lens sheet 30 at the rightmost position PD2R travels towards the sensor 60.

[0097] In the lens sheet 30 shown in Figure 15, the multiple diffusion elements 50 are arranged at the highest density at the central position PD2C in the second direction D2. The density of the multiple diffusion elements 50 gradually decreases along the second direction D2 from the central position PD2C toward the leftmost position PD2L. The density of the multiple diffusion elements 50 gradually decreases along the second direction D2 from the central position PD2C toward the rightmost position PD2R.

[0098] As a result, the light diffusion performance of lens sheet 30 is strongest at the central position PD2C in the second direction D2. The light diffusion performance of lens sheet 30 gradually weakens along the second direction D2 from the central position PD2C towards the leftmost position PD2L. The light diffusion performance of lens sheet 30 gradually weakens along the second direction D2 from the central position PD2C towards the rightmost position PD2R.

[0099] In the luminance angular distribution for each direction in a plane parallel to both the first direction D1 and the second direction D2, the full width at half maximum (FMAX) is largest at the central position PD2C. The FMAX FM gradually decreases from the central position PD2C toward the leftmost position PD2L in the second direction D2. The FMAX FM gradually decreases from the central position PD2C toward the rightmost position PD2R in the second direction D2. As shown in Figure 15, light transmitted through the lens sheet 30 at the central position PD2C is spread over a relatively wide angular range θDC2 and can incident on the entire light-receiving surface of the sensor 60. Light transmitted through the lens sheet 30 at the leftmost position PD2L and the rightmost position PD2R is spread over relatively narrow angular ranges θD2L and θD2R and can incident on the entire light-receiving surface of the sensor 60.

[0100] In the example shown in Figure 15, the lens sheet 30, as a single component, has not only an optical path adjustment function by the lens surface 40 but also an optical diffusion function by multiple diffusion elements 50. The optical path adjustment function and the optical diffusion function are appropriately adjusted at each position in the plane perpendicular to the first direction D1 of the lens sheet 30. More specifically, the optical diffusion function is appropriately adjusted at each position in the plane perpendicular to the first direction D1 of the lens sheet 30 in accordance with the optical path adjustment function. Therefore, the light transmitted through the lens sheet 30 is efficiently diffused without excessive diffusion and directed to the entire light-receiving surface of the sensor 60. The sensor 60 can receive light from the light source module 10 with high sensitivity.

[0101] In an example where the light-receiving sensor 60 faces the lens sheet 30 in the first direction D1, the light diffusion function may be adjusted according to the optical path adjustment function as follows: At a position where the absolute value of the angle that the direction in which the maximum brightness of evaluation item (B) is obtained makes with respect to the first direction D1 is small, the full width at half maximum of evaluation item (C) may be increased. At a position where the absolute value of the angle that the direction in which the maximum brightness of evaluation item (B) is obtained makes with respect to the first direction D1 is large, the full width at half maximum of evaluation item (C) may be decreased. As the absolute value of the angle that the direction in which the maximum brightness of evaluation item (B) is obtained makes with respect to the first direction D1 decreases, the full width at half maximum of evaluation item (C) may be increased. As the absolute value of the angle that the direction in which the maximum brightness of evaluation item (B) is obtained makes with respect to the first direction D1 increases, the full width at half maximum of evaluation item (C) may be decreased.

[0102] In the example described above, the light source module 10 adjusted the optical path of the light emitted from the light source device 20, which is a surface light source device, using a lens sheet 30 (optical element 28). The sensor 60 received light from the light source module 10. However, this example is not the only one.

[0103] The light source device 20 may also be a display element 25. The light source module 10 may also be a display device. Instead of receiving light with the sensor 60, the user, who is the observer, may observe the image displayed by the light source device 20. In this example, the lens sheet 30 (optical member 28) directs the image light incident on each position of the lens sheet 30 towards the eye box 70 where the observer's eye is assumed to be located. However, in actual use, the position of the user's eye may shift in a second direction D2 from the position of the eye box 70. According to the lens sheet 30 shown in Figure 15, the image light transmitted through each position of the lens sheet 30 can be diffused not only to the assumed position of the eye box 70, but also to a position shifted by a predetermined amount in the second direction D2 from the assumed position of the eye box 70.

[0104] The light diffusion performance of the lens sheet 30 differs in the plane perpendicular to the first direction D1. The maximum brightness on the second surface 32 may decrease in areas with strong light diffusion performance. Therefore, the optical characteristics of the light source device 20 used in combination with the lens sheet 30 may be adjusted in advance. Specifically, when light is emitted from the light-emitting surface 21, the standard deviation of the maximum brightness at each position on the second surface 32 of the lens sheet 30 may be smaller than the standard deviation of the maximum brightness at each position on the light-emitting surface 32. According to this example, in addition to appropriately determining the direction in which the maximum brightness is obtained and the full width at half maximum (FM) in the brightness angle distribution, the non-uniformity of brightness on the second surface 32 can be further reduced.

[0105] The maximum brightness on the second surface 32 of the lens sheet 30 is determined by measuring the brightness in all directions at the measurement position on the second surface 32, similar to evaluation item (B) described above, and selecting the maximum value among the brightness measurements. The maximum brightness on the light-emitting surface 21 of the light source device 20 is also determined by measuring the brightness in all directions at the measurement position on the light-emitting surface 21, similar to evaluation item (B) described above, and selecting the maximum value among the brightness measurements.

[0106] The maximum luminance is measured at five measurement positions determined as follows: First, the straight line connecting the centroid of the lens sheet 30 and the point on the outer edge of the lens sheet 30 furthest from the centroid is divided into five equal parts. The center positions of the straight line within each of these small parts of the lens sheet 30 are designated as the five measurement positions. The standard deviation of the maximum luminance is the standard deviation of the maximum luminance measurements taken at the five measurement positions.

[0107] In the embodiment described above, the lens sheet 30 includes a first surface 31 and a second surface 32 facing a first direction D1. At least one of the first surface 31 and the second surface 32 includes a lens surface 40. At least one of the first surface 31 and the second surface 32 includes a plurality of diffusion elements 50. At least one of the shape and density of the plurality of diffusion elements 50, the direction in which maximum brightness is obtained in the brightness angular distribution on the second surface 32 when parallel light parallel to the first direction D1 is incident on the first surface 31, and the full width at half maximum FW in the brightness angular distribution differ among a plurality of positions in a plane perpendicular to the first direction D1.

[0108] According to this embodiment, the lens sheet 30 has different optical properties at multiple positions in a plane perpendicular to the first direction D1. Therefore, a device including the lens sheet 30 according to this embodiment (for example, a light source module 10) can be provided with different optical properties at multiple positions in a plane perpendicular to the first direction D1. Such optical properties are suitable for applications that direct light to a predetermined relative position to the lens sheet 30. Light utilization efficiency can be improved by adjusting the optical path in the lens sheet 30. Furthermore, by making the light diffusion by the diffusion element 50 surface diffusion, stray light can be reduced and the transmittance of the lens sheet 30 can be improved.

[0109] The lens sheet 30 according to this embodiment is suitable, for example, for applications where an optical sensor 60 or other device is positioned at a predetermined relative position to the lens sheet 30, and for applications where an observer is positioned at a predetermined relative position to the lens sheet 30. By using the lens sheet 30 according to this embodiment, the number of optical sheets included in a device with complex optical properties (e.g., a light source module 10) can be reduced. Therefore, the device with complex optical properties (e.g., a light source module 10) can be made thinner and lighter.

[0110] In one specific example of this embodiment, one of the first surface 31 and the second surface 32 may include a lens surface 40. The other of the first surface 31 and the second surface 32 may include a plurality of diffusion elements 50. According to this specific example, the lens surface 40 provided on one of the first surface 31 and the second surface 32 allows for a high degree of freedom in adjusting the direction in which maximum brightness is obtained on the second surface 32 at multiple positions within the surface. The plurality of diffusion elements 50 provided on the other of the first surface 31 and the second surface 32 allow for a high degree of freedom in adjusting the full width at half maximum FW in the brightness angular distribution on the second surface 32 at multiple positions within the surface. Therefore, the lens sheet 30 according to this specific example can impart more complex optical characteristics to devices such as the light source module 10.

[0111] In one specific example of this embodiment, one of the first surface 31 and the second surface 32 may include both the lens surface 40 and a plurality of diffusion elements 50. According to this specific example, the lens sheet 30 and the device including the lens sheet 30 (e.g., the light source module 10) can be made thinner. Furthermore, the lens sheet 30 can be bonded to other optical sheets or other members on the other of the first surface 31 and the second surface 32 by a bonding layer containing an adhesive or the like. By bonding the lens sheet 30 to other members, the device including the lens sheet 30 (e.g., the light source module 10) can achieve the expected optical characteristics with high precision.

[0112] In one specific example of this embodiment, the lens sheet 30 may include a plurality of lens elements 45, each including a lens surface 40. The plurality of lens elements 45 may be arranged in a second direction D2 that is not parallel to the first direction D1. Each of the plurality of lens elements 45 may extend linearly in a direction not parallel to the first direction D1 and the second direction D2. According to this specific example, the lens surface 40 can be greatly inclined with respect to a plane perpendicular to the first direction D1 while suppressing an increase in the thickness of the lens sheet 30. That is, the optical path of incident light can be greatly bent by a thin lens sheet 30. More complex optical properties can be imparted to a thin lens sheet 30.

[0113] In one specific example of this embodiment, the lens sheet 30 may include a plurality of lens elements 35, each including a lens surface 40. The plurality of lens elements 35 may be arranged concentrically. According to this specific example, the lens surface 40 can be significantly inclined with respect to a plane perpendicular to the first direction D1 while suppressing an increase in the thickness of the lens sheet 30. In other words, the optical path of incident light can be significantly bent by a thin lens sheet 30. More complex optical properties can be imparted to a thin lens sheet 30.

[0114] In one specific example of this embodiment, the lens sheet 30 may include a Fresnel lens 47. The Fresnel lens 47 may include a plurality of lens elements 45 constituting the lens surface 40, and rise surfaces 43 arranged alternately with each of the plurality of lens elements 45. According to this specific example, the lens surface 40 can be greatly inclined with respect to a plane perpendicular to the first direction D1 while suppressing an increase in the thickness of the lens sheet 30. In other words, the optical path of incident light can be greatly bent by a thin lens sheet 30. More complex optical properties can be imparted to a thin lens sheet 30.

[0115] This embodiment has been described with reference to specific examples, but the above-mentioned examples do not limit this embodiment. The above-described embodiment can be implemented in various other examples, and various omissions, substitutions, modifications, and additions can be made without departing from its essence. [Explanation of Symbols]

[0116] 10: Light source module, 20: Light source device, 21: Light-emitting surface, 25: Display element, 28: Optical component, 30: Lens sheet, 31: First surface, 32: Second surface, 36: First layer, 37: Second layer, 38: Third layer, 40: Lens surface, 41: Lens element surface, 43: Rise surface, 45: Lens element, 47: Fresnel lens, 50: Diffusion element, 51: Concave / concave element, 51: Surface layer, 52: Particle, 53: Binder component, 60: Sensor, 70: Eyebox, D1: First direction, D2: Second direction, D3: Third direction, PD2C: Center position, PD2L: Left position, PD2R: Right position, θD2C: Angular range, θD2L: Angular range, θD2R: Angular range

Claims

1. It comprises a first surface and a second surface facing each other in the first direction, At least one of the first and second surfaces includes a lens surface, At least one of the first and second surfaces includes a plurality of diffusion elements, A lens sheet wherein at least one of the shapes and densities of the plurality of diffusing elements, the direction in which maximum brightness is obtained in the brightness angular distribution on the second surface when parallel light parallel to the first direction is incident on the first surface, and the full width at half maximum in the brightness angular distribution differ among a plurality of positions in a plane perpendicular to the first direction.

2. One of the first and second surfaces includes the lens surface, The lens sheet according to claim 1, wherein the other of the first and second surfaces includes the plurality of diffusion elements.

3. The lens sheet according to claim 1, wherein one of the first and second surfaces includes both the lens surface and the plurality of diffusion elements.

4. The lens comprises a plurality of lens elements including the aforementioned lens surface, The plurality of lens elements are arranged in a second direction that is not parallel to the first direction, The lens sheet according to claim 1, wherein each of the plurality of lens elements extends linearly in a direction nonparallel to the first direction and the second direction.

5. The lens comprises a plurality of lens elements including the aforementioned lens surface, The lens sheet according to claim 1, wherein the plurality of lens elements are arranged in a concentric circle.

6. The lens sheet according to claim 1, comprising a Fresnel lens including a plurality of lens element surfaces constituting the lens surface and rise surfaces arranged alternately with each of the plurality of lens element surfaces.

7. A light source device including a light-emitting surface, A lens sheet as described in any one of claims 1 to 6, A light source module in which the lens sheet is superimposed on the light source device in the first direction such that the first surface and the light-emitting surface face each other in the first direction.

8. The light source module according to claim 7, wherein, in a state in which light is emitted from the light-emitting surface, the standard deviation of the maximum brightness at each position on the second surface of the lens sheet is smaller than the standard deviation of the maximum brightness at each position on the light-emitting surface.

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