WO2015144990A1

WO2015144990A1 - A lens for modifying a light distribution pattern

Info

Publication number: WO2015144990A1
Application number: PCT/FI2015/050205
Authority: WO
Inventors: Olli Hakala
Original assignee: Ledil Oy
Priority date: 2014-03-28
Filing date: 2015-03-26
Publication date: 2015-10-01

Abstract

A lens modifying a light distribution pattern of a light source is presented. The lens comprises transparent material whose refractive index is greater than unity. The lens comprises a first surface (205) suitable for a receiving light, and a second surface (204) comprising for acting as a light egress surface. The first surface is shaped to have a Fresnel pattern so as provide an optical effect achievable with a convex surface and the Fresnel pattern is asymmetrical so that the light distribution pattern is turned by the lens with respect to a normal of the second surface.

Description

A lens for modifying a light distribution pattern

Field of the invention

The invention relates generally to illumination engineering. More particularly, the invention relates to a lens for modifying a light distribution pattern of a light source that can be, for example but not necessarily, a light emitting diode "LED".

Background

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. In many cases there is a need for an illuminator device system which can be embedded in a cavity of a wall or another structure and whose outward facing surface needs to be substantially flat. Figure 1 a shows a section view of an exemplifying illuminator system of the kind mentioned above. The illuminator device shown in figure 1 a comprises a light source 102 that can be e.g. a light emitting diode "LED" and a lens 101 for modifying the light distribution pattern of the light source. As shown in figure 1 a, the illuminator system is partially embedded in a cavity of a wall 103.The the illuminator system is advantageously linear, i.e. has a substantially constant cross-section, in the x-direction of a coordi- nate system 199.

In many cases, there is a need that the light distribution pattern is directed in the way as presented in figure 1 b so that the main axis of the light distribution pattern has an angle a with respect to the y-axis of the coordinate system 199.

Summary The following presents a simplified summary in order to provide a 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 fol- lowing summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments of the invention.

In accordance with the invention, there is provided a new lens for modifying the light distribution patterns of a light source. A lens according to the invention comprises transparent material whose refractive index is greater than unity. The lens comprises:

- a first surface suitable for a receiving light, and

- a second surface for acting as a light egress surface, wherein the first surface is shaped to have a Fresnel pattern so as provide an optical effect achievable with a convex surface.

The Fresnel pattern is asymmetrical so that the light distribution patter is turned by the lens with respect to a normal of the second surface.

The second surface is advantageously substantially flat. The lens is advantageously substantially linear so that its cross-section is substantially constant when the section plane is moved a distance along a line perpendicular to the section plane.

The lens comprises advantageously one or more grooves substantially perpendicular to the above-mentioned line and enabling the lens to be divided into two or more pieces by bending the lens along the grooves. Therefore, the lens can be adapted to be suitable for different applications where different numbers of lenses are needed.

The term "lens" has to be understood in the broad sense so that the term "lens" is not limited to typical convex and concave lenses but a lens may comprise for ex- ample planar facets and edges between adjacent facets. Furthermore, a lens may comprise a roughened surface for smoothing the light distribution pattern. Yet furthermore, a lens may comprise converging and diverging undulations so that the surfaces provided with the undulations are color mixing surfaces. In a color mixing surface, light beams exhibiting different wavelengths are effectively mixed thus producing a light distribution pattern which contains all wavelengths evenly distributed across the light distribution pattern, and thus a solid light distribution pattern can be achieved. In accordance with the invention, there is provided also a new illuminator device comprising one or more light sources and a lens according to the invention. Each light source can be, for example, a light emitting diode "LED".

In accordance with the invention, there is provided also a new mold for manufacturing, by mold casting, a lens according to the invention. A number of exemplifying and non-limiting embodiments of the invention are described in accompanied dependent claims.

Various exemplifying and non-limiting embodiments of the invention 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 spe- cific exemplifying embodiments when read in connection with the accompanying drawings.

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. The features recited in depending claims are mutually freely combinable unless other- wise explicitly stated. 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.

Brief description of drawings

Figures 1 a and 1 b shows an illumination device structure according to the prior art, and figures 2a, 2b, and 2c illustrate a lens according to an exemplifying and non- limiting embodiment of the invention for modifying the light distribution patterns of light sources. Description of exemplifying embodiments

Figures 2a, 2b, and 2c illustrate a lens 201 according to an exemplifying and non- limiting embodiment of the invention for modifying the light distribution patterns of light sources. Figure 2a shows an isometric view of the lens 201 .

Figure 2b shows a section view of the lens 201 . The section plane is parallel with the yz-plane of a coordinate system 299. Some of light beams emitted by a light source are depicted with dashed-line arrows in figure 2b.

Figure 2c shows a side view of the lens 201 . The lens 201 is made of transparent material whose refractive index is greater than one, i.e. > 1 .00. The transparent material can be for example acrylic plastic or polycarbonate. The method of manufacture of the lens 201 can be for example mold casting.

The lens 201 comprises: - a first surface 205 suitable for a receiving light, and

- a second surface 204 comprising for acting as a light egress surface.

As illustrated in figure 2b, the first surface 205 is shaped to have a Fresnel pattern so as provide an optical effect achievable with a convex surface.

As illustrated in figure 2b, the Fresnel pattern is asymmetrical with respect to the second surface so that the light distribution patter is turned by the lens with respect to a normal of the second surface as illustrated by the dashed line arrows shown in figure 2b.

The second surface is advantageously, but not necessarily, substantially flat as illustrated in figures 2b and 2c. The lens is advantageously substantially linear so that its cross-section is substantially constant when the section plane is moved a distance along a line perpen- dicular to the section plane and parallel with the x-axis of the coordinate system 299.

As illustrated in figures 2a and 2c, the lens comprises advantageously one or more grooves 206a, 206b substantially perpendicular to the above-mentioned line and enabling the lens 201 to be divided into two or more pieces by bending the lens along the grooves. Therefore, the lens can be adapted to be suitable for different applications where different numbers of lenses are needed.

The specific examples provided in the description given above should not be construed as limiting the scope and/or the applicability of the appended claims.

Claims

What is claimed is:

1 . A lens modifying a light distribution pattern of a light source, the lens comprising:

- a first surface (205) for a receiving light, and - a second surface (204) for acting as a light egress surface, wherein the first surface is shaped to have a Fresnel pattern so as provide an optical effect achievable with a convex surface and the Fresnel pattern is asymmetrical so that the light distribution patter is turned by the lens with respect to a normal of the second surface.

2. A lens according to claim 1 , wherein the second surface is substantially flat.

3. A lens according to claim 1 , wherein the lens is substantially linear so that its cross-section is substantially constant when the section plane is moved a distance along a line perpendicular to the section plane.

4. A lens according to claim 3, wherein the lens comprises one or more grooves (206a, 206b) substantially perpendicular to the above-mentioned line and enabling the lens to be divided into two or more pieces by bending the lens along the grooves.

5. A mold having a form suitable for manufacturing, by mold casting, the lens according to any of claims 1 -4.