A lens for modifying a light distribution
The lens design addresses the challenge of achieving sharp cut-off and even light distribution by focusing light beams to different points perpendicular to the optical axis, enhancing light distribution with non-point-form sources.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- LEDIL
- Filing Date
- 2025-09-18
- Publication Date
- 2026-05-21
AI Technical Summary
Conventional Fresnel lenses struggle to achieve sufficient collimation and sharp cut-off in light distribution patterns when used with light sources that are not point-form, such as planar light emitting surfaces, due to challenges in focusing light beams effectively.
A lens design with a Fresnel pattern on one surface that focuses light beams to different focus points in directions perpendicular to the geometric optical axis, allowing for a light distribution pattern with a sharp cut-off, even with non-point-form light sources.
The lens achieves well-collimated light distribution with a sharp cut-off by aligning focus points on a geometric plane perpendicular to the optical axis, improving light intensity distribution and cut-off regions.
Smart Images
Figure EP2025076731_21052026_PF_FP_ABST
Abstract
Description
[0001] A lens for modifying a light distribution
[0002] Field
[0003] The invention relates generally to illumination engineering. More particularly, the invention relates to a lens for modifying distribution of light produced by a light source that can be, for example but not necessarily, a light emitting diode “LED”. Furthermore, the invention relates to a light fixture comprising a light source and a lens configured to modify a distribution of light produced by the light source.
[0004] Background
[0005] Distribution of light produced by a light source can be important or even critical in some applications. The light source can be, for example but not necessarily, a light emitting diode “LED”, a filament lamp, or a gas-discharge lamp. The distribution of light produced by a light source can be modified with optical devices such as lenses, reflectors, and combined lens-reflector devices that comprise sections which act as lenses and sections which act as reflectors. In many cases, an optical device which has desired optical properties may be inconvenient in other respects. For example, a conventional spherical plano-convex lens which has a large aperture and a short focal length can be thick in the direction of the geometric optical axis of the lens and thus the lens can be unsuitable for many applications.
[0006] A Fresnel lens represents a lens design which allows constructions of lenses having large apertures and short focal lengths without thickness in the direction of the geometric optical axis that would be required by a corresponding conventional lens. Thus, a Fresnel lens can be made much thinner than a comparable conventional lens. The design of a Fresnel lens effectively divides a continuous lens surface into a set of concentric and annular ridges with stepwise discontinuities between adjacent ones of the ridges.
[0007] In a typical Fresnel lens design, lens surfaces of the above-mentioned ridges are shaped to focus collimated light beams arriving in parallel with the geometric optical axis of the lens to a focus point on the geometric optical axis of the lens. Based on the principle of reciprocity of light propagation, a Fresnel lens of the kind mentioned above is capable of collimating light beams emitted by a point-form light source placed at the above-mentioned focus point. It is however more challenging to achieve a sufficient collimation effect and thereby a light distribution pattern with a sufficiently sharp cut-off when a light source is not a point-form light source, but the light source has e.g. a planar light emitting surface “LES”
[0008] Summary
[0009] The following presents a simplified summary to provide basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments.
[0010] In this document, the word “geometric” when used as a prefix means a geometric concept that is not necessarily a part of any physical object. The geometric concept can be for example a geometric point, a straight or curved geometric line, a geometric plane, a non-planar geometric surface, a geometric space, or any other geometric entity that is zero, one, two, or three dimensional.
[0011] In accordance with the invention, there is provided a new lens for modifying a distribution of light produced by a light source.
[0012] A lens according to the invention comprises:
[0013] - a first surface on a first side of the lens, and
[0014] - a second surface on a second side of the lens, the first and second sides of the lens being opposite sides of the lens.
[0015] The first surface of the lens has a Fresnel pattern suitable for refracting light beams arriving at the first surface in parallel with a geometric optical axis of the lens. The first surface comprises areas such that different ones of the areas are shaped to focus the light beams arriving at the areas so that focus points related to the different ones of the areas have different locations in one or more directions perpendicular to the geometric optical axis of the lens.
[0016] In many lenses according to embodiments of the invention, one or more of the above-mentioned areas each corresponding to a respective focus point comprise many parts which are not connected to each other, i.e. an area related to a focus point does not need to be a connected area.
[0017] In a lens according to an exemplifying and non-limiting embodiment, the focus points related to the different ones of the areas of the first surface are on same geometric plane perpendicular to the geometric optical axis of the lens. When a light emitting surface of a light source is positioned to coincide with a part defined by the focus points on the above-mentioned geometric plane, light beams emitted from the light source are well collimated based on the principle of reciprocity of light propagation and thereby a light distribution pattern with a sufficiently sharp cut-off can be achieved even if the light source is not a point-form light source.
[0018] In accordance with the invention, there is also provided a new mold having a form suitable for manufacturing, by mold casting, a transparent piece constituting a lens according to the invention.
[0019] In accordance with the invention, there is also provided a new light fixture that comprises:
[0020] - a light source having a light emitting surface, and
[0021] - a lens according to the invention and mechanically supported with respect to the light source so that the geometric optical axis of the lens intersects the light emitting surface perpendicularly at a center-of-mass point of the light emitting surface.
[0022] Exemplifying and non-limiting embodiments are described in accompanied dependent claims.
[0023] Exemplifying and non-limiting embodiments both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying embodiments when read in conjunction with the accompanying drawings.
[0024] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features.
[0025] The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated.
[0026] Furthermore, it is to be understood that the use of “a” or “an”, i.e. a singular form, throughout this document does not exclude a plurality.
[0027] Brief description of figures
[0028] Exemplifying and non-limiting embodiments and their advantages are explained in greater detail below with reference to the accompanying drawings, in which:
[0029] Figures 1a and 1b illustrate a lens according to an exemplifying and non-limiting embodiment,
[0030] Figure 2 illustrate a lens according to an exemplifying and non-limiting embodiment,
[0031] Figure 3 illustrate a lens according to an exemplifying and non-limiting embodiment,
[0032] Figure 4 illustrates a light fixture that comprises a light source and a lens according to an exemplifying and non-limiting embodiment for modifying a distribution of light produced by the light source, and
[0033] Figures 5a and 5b illustrate functionality of a lens according to an exemplifying and non-limiting embodiment compared to corresponding functionality of a lens according to the prior art.
[0034] Description of exemplifying and non-limiting embodiments
[0035] The specific examples provided in the description given below should not be construed as limiting the scope and / or the applicability of the invention. Lists and groups of examples provided in the description given below are not exhaustive unless otherwise explicitly stated. Figure 1a shows a section view of a lens 100 according to an exemplifying and nonlimiting embodiment. Figure 1b shows a magnification of a part 113 of figure 1a. The geometric section plane related to figures 1a and 1b is parallel with the xz-plane of a coordinate system 199. The lens 100 is made of transparent material that can be for example acrylic plastic, polycarbonate, optical silicone, or glass. The lens 100 can be manufactured for example by mold casting.
[0036] The lens 100 comprises a first surface 101 on a first side of the lens and a second surface 102 on a second side of the lens, where the first and second sides of the lens are opposite sides of the lens. The first surface 101 of the lens has a Fresnel pattern suitable for refracting light beams arriving at the first surface 101 in parallel with a geometric optical axis 103 of the lens. In figure 1a, the geometric optical axis 103 is depicted with a dash-and-dot line. The first surface 101 comprises areas such that different ones of the areas are shaped to focus the light beams arriving at the areas so that focus points related to the different ones of the areas have different locations in one or more directions perpendicular to the geometric optical axis 103 of the lens. In this exemplifying case, the focus points are on a geometric plane 110 that is perpendicular to the geometric optical axis 103 of the lens. In figure 1a, the geometric plane 110 is parallel with the xy-plane of the coordinate system 199. In figure 1a, three of the focus points are denoted with references 107, 108, and 109. These focus points 107-109 correspond to areas 104, 105, and 106 illustrated in figure 1b. In figures 1a and 1b, exemplifying light beams are depicted with dashed lines. In the exemplifying lens 100, the second surface 102 is planar but also other shapes being possible for the second surface 102 depending on optical requirements related to the lens.
[0037] In the exemplifying lens 100 illustrated in figures 1a and 1b, ridges of the Fresnel pattern are shaped so that the area 104 of the lens surface of each ridge that is nearer to the top of the ridge is shaped to refract light by a different angle than the area 106 of the lens surface of the ridge nearer to the bottom between the ridge and an adjacent one of the ridges, i.e. ai + as in figure 1b. In the exemplifying lens 100 illustrated in figures 1a and 1b, the lens surface of the ridge shown in figure 1b also comprises an area 105 between the above-mentioned areas 104 and 106. The area 104 corresponds to the focus point 109, the area 105 corresponds to the focus point 108, and the area 106 corresponds to the focus point 107. Therefore, ai < a2 < as in figure 1b. In an exemplifying case where the Fresnel pattern is rotationally symmetric with respect to the geometric optical axis 103, the ridges of the Fresnel pattern are circular when the lens 100 is seen along the geometric optical axis 103. In this exemplifying case, the focus points draw concentric rings on the geometric plane 110 and thus define a substantially circular part on the geometric plane 110 when seen along the geometric optical axis 103. It is to be, however, noted that the Fresnel pattern is not necessarily rotationally symmetric but can have another shape, too. Furthermore, it is to be noted that figures 1 a and 1 b describe a simplified design for illustrative purposes, and, in a lens according to an exemplifying and nonlimiting embodiment, the lens surfaces of the Fresnel pattern may have a high number of areas and correspondingly there can be a high number of focus points between the focus points 107 and 108. Furthermore, it is also possible to shape the lens surfaces of the Fresnel pattern so that there are infinitely many focus points between the focus points 107 and 108 in which case the geometric plane 110 intersects a waist of a light distribution.
[0038] Figure 2 shows a section view of a lens 200 according to an exemplifying and nonlimiting embodiment. The geometric section plane is parallel with the xz-plane of a coordinate system 299. The lens 200 comprises a first surface 201 and a second surface 202 on opposite sides of the lens. The first surface 201 of the lens has a Fresnel pattern suitable for refracting light beams arriving at the first surface 201 in parallel with a geometric optical axis 203 of the lens. In figure 2, the geometric optical axis 203 is depicted with a dash-and-dot line and exemplifying light beams are depicted with dashed lines. The first surface 201 comprises areas such that different ones of the areas are shaped to focus the light beams arriving at the areas so that focus points related to the different ones of the areas have different locations in one or more directions perpendicular to the geometric optical axis 203 of the lens. In this exemplifying case, the focus points are on a geometric plane 210 that is perpendicular to the geometric optical axis 203 of the lens. In figure 2, the geometric plane 210 is parallel with the xy-plane of the coordinate system 199. In figure 2, three of the focus points are denoted with references 207, 208, and 209. These focus points 207-209 correspond to areas 204, 205, and 206 illustrated in figure 2. In the exemplifying lens 200 illustrated in figure 2, lens surfaces of different ones of the ridges of the Fresnel pattern represent different ones of the above-mentioned areas of the first surface 201. In the exemplifying case shown in figure 2, the ridge whose lens surface is the area 204 corresponds to the focus point 207, the ridge whose lens surface is the area 205 corresponds to the focus point 208, and the ridge whose lens surface is the area 206 corresponds to the focus point 209. In an exemplifying case where the lens 200 is rotationally symmetric with respect to the geometric optical axis 203, the focus points draw concentric rings on the geometric plane 210 that is perpendicular to the geometric optical axis 203 of the lens 200.
[0039] Figure 3 shows a lens 300 according to an exemplifying and non-limiting embodiment when seen along a geometric optical axis that is parallel with the z-axis of a coordinate system 399. The lens 300 comprises a first surface 301 and a second surface on the opposite side of the lens. The first surface 301 of the lens has a Fresnel pattern suitable for refracting light beams arriving at the first surface 301 in parallel with the geometric optical axis 303 of the lens. The first surface 301 comprises areas such that different ones of the areas are shaped to focus the light beams arriving at the areas so that focus points related to the different ones of the areas have different locations in one or more directions perpendicular to the geometric optical axis of the lens, i.e. the focus points have the different locations in the x and / or y directions of the coordinate system 399.
[0040] In the exemplifying lens 300 illustrated in figure 3, lens surfaces of the ridges of the Fresnel pattern have circumferentially successive sections representing the above-mentioned areas of the first surface 301 shaped to focus the light beams arriving at the areas so that the focus points related to the different ones of the areas have the different locations in the one or more directions perpendicular to the geometric optical axis of the lens. In figure 3, three circumferentially successive sections of one ridge of the Fresnel pattern are denoted with references 304, 305, and 306.
[0041] Figure 4 shows a section view of a light fixture according to an exemplifying and non-limiting embodiment. The geometric section plane is parallel with the xz-plane of a coordinate system 499. The light fixture comprises a light source 411, e.g. a light emitting diode “LED”, which has a light emitting surface “LES” 412. The light fixture comprises a lens 400 according to an exemplifying and non-limiting embodiment for modifying a distribution of light produced by the light source 411. Exemplifying light beams are depicted with dashed lines. The lens 400 is mechanically supported with respect to the light source 411 so that a geometric optical axis 403 of the lens 400 intersects the light emitting surface 412 perpendicularly at the center-of-mass point of the light emitting surface. In this exemplifying case, the lens 400 is like the lens 100 illustrated in figures 1a and 1b. It is however also possible that the lens 400 is like the lens 200 illustrated in figure 2, or like the lens 300 illustrated in figure 3, or a lens according to some other embodiment of the invention. The lens 400 comprises a first surface 401 and a second surface 402 on opposite sides of the lens. The first surface 401 of the lens 400 has a Fresnel pattern for collimating light beams received from the light emitting surface 412 of the light source 411. The first surface 401 comprises areas such that different ones of the areas of the first surface 401 correspond to focus points at different locations in one or more directions perpendicular to the geometric optical axis of the lens, i.e. the focus points have the different locations in the x and / or y directions of the coordinate system 499.
[0042] In a light fixture according to an exemplifying and non-limiting embodiment, the lens 400 is such that the focus points which corresponds to different ones of the areas of the first surface 401 are on a same geometric plane 410 that is perpendicular to the geometric optical axis 403 of the lens 400. In this exemplifying case, the light emitting surface 412 of the light source 411 can be arranged to coincide with a part of the geometric plane 410, where the part is defined by the focus points related to the different ones of the areas of the first surface 410 of the lens 400.
[0043] Figure 5a illustrates functionality of a lens according to an exemplifying and nonlimiting embodiment when a light source has a light emitting surface and thereby the light source is not a point-form light source. In this exemplifying case, the lens according to the exemplifying and non-limiting embodiment is like the lens 100 illustrated in figures 1a and 1b. Figure 5a shows a light distribution pattern on a screen perpendicular to the geometric optical axes of the lens according to the exemplifying and non-limiting embodiment. Figure 5b illustrates functionality of a corresponding lens according to the prior art which has been designed for a point-form light source. Figure 5b shows a light distribution pattern on a screen perpendicular to the geometric optical axes of the lens according to the prior art when a similar, non-point-form, light source is used as in conjunction with the lens according to the exemplifying and non-limiting embodiment.
[0044] As can be seen, the light distribution pattern shown in figure 5a and obtained with the lens according to the exemplifying and non-limiting embodiment has a more even light intensity distribution and a sharper cut-off region than the corresponding light distribution pattern shown in figure 5a and obtained with the lens according to the prior art and designed for a point-form light source.
[0045] The specific examples provided in the description given above should not be construed as limiting the scope and / or the applicability of the invention. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.
Claims
What is claimed is:
1. A lens (100, 200, 300, 400) for modifying a light distribution, the lens being made of transparent material and comprising:- a first surface (101 , 201 , 301 , 401 ) on a first side of the lens, and- a second surface (102, 202, 402) on a second side of the lens, the first and second sides of the lens being opposite sides of the lens,wherein the first surface of the lens has a Fresnel pattern for refracting light beams arriving at the first surface in parallel with a geometric optical axis (103, 203, 403) of the lens, characterized in that the first surface comprises areas (104, 105, 106, 204, 205, 206, 304, 305, 306) such that different ones of the areas are shaped to focus the light beams arriving at the areas so that focus points (107, 108, 109, 207, 208, 209) related to the different ones of the areas have different locations in one or more directions perpendicular to the geometric optical axis of the lens.
2. A lens (100, 200, 400) according to claim 1, wherein the focus points related to the different ones of the areas are on a geometric plane (110, 210, 410) perpendicular to the geometric optical axis of the lens.
3. A lens (100) according to claim 1 or 2, wherein ridges of the Fresnel pattern are shaped so that an area (104) of a lens surface of each ridge nearer to a top of the ridge is shaped to refract light by a different angle (ai + as) than an area (106) of the lens surface of the ridge nearer to a bottom between the ridge and an adjacent one of the ridges.
4. A lens (100) according to claim 3, wherein the area (104) of the lens surface of the ridge nearer to the top of the ridge is shaped to refract light less (ai < as) than the area (106) of the lens surface of the ridge nearer to the bottom between the ridge and the adjacent one of the ridges.
5. A lens (200) according to claim 1 or 2, wherein lens surfaces of different ones of ridges of the Fresnel pattern represent the different ones of the areas (204, 205,6. A lens according to any one of claims 1 -5, wherein ridges of the Fresnel pattern are circular when seen along the geometric optical axis of the lens.
7. A lens according to claim 6, wherein the Fresnel pattern is rotationally symmetric with respect to the geometric optical axis of the lens.
8. A lens (300) according to claim 6, wherein the ridges of the Fresnel pattern have circumferentially successive sections representing the areas (304, 305, 306) of the first surface shaped to focus the light beams arriving at the areas so that the focus points related to the different ones of the areas have the different locations in the one or more directions perpendicular to the geometric optical axis of the lens.
9. A lens (100, 200, 400) according to any one of claims 6-8, wherein the focus points related to the different ones of the areas of the first surface are on a / the geometric plane (110, 210, 410) perpendicular to the geometric optical axis (103, 203, 403) of the lens, and the focus points define a substantially circular part on the geometric plane.
10. A lens (300) according to claim 1 or 2, wherein ridges of the Fresnel pattern are circular when seen along the geometric optical axis of the lens, and the ridges of the Fresnel pattern have circumferentially successive sections representing the areas (304, 305, 306) of the first surface shaped to focus the light beams arriving at the areas so that the focus points related to the different ones of those of the areas which are circularly successive and belong to a same one of the ridges of the Fresnel pattern have the different locations in the one or more directions perpendicular to the geometric optical axis of the lens.
11. A lens according to any one of claims 1 -10, wherein the transparent material is one of following: acrylic plastic, polycarbonate, optical silicone, glass.
12. A mold having a form suitable for manufacturing, by mold casting, a transparent piece constituting a lens according to any one of claims 1-11.
13. A light fixture comprising:a light source (411) having a light emitting surface (412), and- a lens (400) according to any one of claims 1 -11 and mechanically supported with respect to the light source so that the geometric optical axis (403) of the lens intersects the light emitting surface perpendicularly at a center-of-mass point of the light emitting surface.
14. A light fixture according to claim 13, wherein the lens is according to claim 2, and the light emitting surface (412) of the light source coincides with a part of the geometric plane (410) perpendicular to the geometric optical axis of the lens, the part being defined by the focus points related to the different ones of the areas of the first surface of the lens.