Field of technology

The disclosure relates generally to illumination engineering. More particularly, the disclosure relates to an optical system for modifying a light distribution pattern.

Background

Distribution of light produced by one or more light sources can be important or even critical in some applications. Each light source can be, for example but not necessarily, a light emitting diode "LED", a filament lamp, a fluorescent lamp, or a gas-discharge lamp. In many cases, an illumination system comprises a body structure provided with one or more light sources and one or more lens elements that are attached to the body structure so that the distribution of the light emitted by the light sources is modified by the lens elements. Especially in outdoor use, an illumination system of the kind mentioned above should be at least dustproof and sometimes also waterproof. This requirement means typically that for example the joints between the lens elements and the body structure have to be sealed joints.

A straightforward approach is to arrange a separate sealing arrangement for each of the above-mentioned lens elements. For example, the surface of each lens element which is against the respective surface of the body structure can be provid- ed with an O-ring seal that is located in an appropriately dimensioned groove of the lens element. An inconvenience related to this approach is that there is a need for O-rings of different sizes when there are lens elements of different sizes. Thus, there is a need to purchase and store O-rings of different sizes or to fabricate O- rings of different sizes using suitable strip of flexible material as a starting point. Another inconvenience related to separately sealed lens elements is brought forth in cases where there is a need to arrange for example cooling flows into spatial rooms that are limited by the lens elements together with the body structure. In these cases, it would be more convenient if all the lens elements could be sealed with a common sealing arrangement so that the above-mentioned spatial rooms are connected to each other with flow passages.

Summary

The following presents a simplified summary in order to provide a basic under- standing 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 of the invention.

In accordance with the invention, there is provided a new optical system for modifying a light distribution pattern. An optical system according to the invention comprises:

- one or more lens elements for modifying the light distribution pattern, - support elements for supporting the lens elements so that the lens elements are secured to an external body structure, and

- elongated seal sections for constituting elongated sealing contact areas with the lens elements and with the external body structure.

Each of at least two of the above-mentioned support elements comprises a sealing section for constituting auxiliary sealing contact areas with at least one of the lens elements and with the external body structure so that the auxiliary sealing contact areas constitute a substantially ring-shaped sealing contact area that surrounds at least one of end-sections of the lens elements and those portions of the elongated seal sections which are in touch with the surrounded at least one end-section.

The sealing sections of the support elements and the elongated seal sections are arranged to seal one or more spatial rooms from the ambient when the support elements are supporting the lens elements so that the lens elements are secured to the external body structure, where the sealed one or more spatial rooms are between the lens elements and the external body structure.

The above-presented sealing achievable with the support elements makes it unnecessary to seal each of the lens elements separately. The term "lens" in conjunction with the above-mentioned lens elements 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 example 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 illumination system comprising one or more light sources, a body structure, and an optical system 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 manufac- turing, by mold casting, one or more support elements of an optical system according to the invention. Also the lens elements of the optical system can be manufactured by the mold casting.

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 specific 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 dependent claims are mutually freely combinable unless otherwise 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 the figures

Exemplifying and non-limiting embodiments of the invention and their advantages are explained in greater detail below with reference to the accompanying drawings, in which: figures 1 a, 1 b, 1 c, 1 d, 1 e, and 1 f illustrate an optical system according to an exemplifying and non-limiting embodiment of the invention, and figure 2 illustrates an optical system according to another exemplifying and non- limiting embodiment of the invention.

Description of exemplifying embodiments Figure 1 a shows an illumination system that comprises an optical system according to an exemplifying and non-limiting embodiment of the invention. Figure 1 b shows a view of a section taken along a line A-A shown in figure 1 a. The section plane is parallel with the xz-plane of a coordinate system 199. The illumination system further comprises light sources and a body structure 1 14. Each of the light sources can be, for example but not necessarily, a light emitting diode "LED", a filament lamp, a fluorescent lamp, or a gas-discharge lamp. In figure 1 b, one of the light sources is denoted with a reference number 1 15. The optical system comprises lens elements 101 , 102, and 103 for modifying the light distribution pattern produced by the light sources. The portion of each lens element which covers the respective light sources is shaped to constitute lenses for modifying the light distribution pattern. In this exemplifying case, the above-mentioned portion of each lens element is shaped to constitute a plurality of lenses one of which is denoted with a reference number 1 16 in figures 1 a and 1 b. An exemplifying light beam which has penetrated the lens element 101 is depicted with a dashed line arrow in figure 1 b. The lens elements 101 -103 are made of transparent material whose refractive index is greater than one. The transparent material can be for example acrylic plastic, polycarbonate, or some other suitable transparent material.

The optical system comprises support elements 104, 105, 106, and 107 for sup- porting the lens elements 101 -103 so that the lens elements are secured to the body structure 1 14 and the lens elements define, together with the body structure, spatial rooms between the lens elements and the body structure. In the exemplifying illumination system shown in figure 1 a and 1 b, the support elements 104-107 comprise screws for fastening on the body structure 1 14. It is also possible that the support elements comprise other fastening means such as e.g. fastening clips instead of or in addition to the screws.

Figures 1 c and 1 d show exploded perspective views of a portion B of the illumination system, and figures 1 e and 1 f show exploded perspective views of a portion C of the illumination system. Figures 1 c and 1 d show the support element 107 and a part of the lens element 103. Figures 1 e and 1 f show the support element 106 and parts of the lens elements 102 and 103. The viewing directions related to figures 1 c-1 f are illustrated with the aid of the coordinate system 199.

The optical system comprises elongated seal sections for constituting elongated sealing contact areas with the lens elements 101 -103 and with the body structure 1 14. The elongated seal sections are denoted with reference numbers 108 and 109 in figures in figures 1 c, 1 d, and 1 f which show parts of the elongated seal sections. The body structure is not shown in figures 1 c-1 f but from figures 1 a-1 f it can be understood that the elongated seal sections 108 and 109 constitute the elongated sealing contact areas with the lens elements 101 -103 and with the body structure 1 14. In this exemplifying case, the elongated seal sections 108 and 109 are strings having a substantially circular cross-section and made of flexible material, e.g. rubber. Other kinds of elongated seal sections are however possible too. Furthermore, it is also possible that the elongated seal sections are coated with a layer of adhesive material capable of adhering to the external body structure and/or to the lens elements. As illustrated in figure 1 c, an end-portion 1 17 of the lens element 103 comprises slots 1 12 and 1 13 for fastening the elongated seal sections 108 and 109 on the lens element 103. As illustrated in figure 1 f, the elongated seal sections 108 and 109 reach from the lens element 102 to the lens element 103 over the boundary area between these lens elements. Correspondingly, the elongated seal sections 108 and 109 can be continuous also over the boundary area between the lens elements 101 and 102. It is also possible that one or both of the elongated seal sections 108 and 109 is/are discontinuous on the boundary area between the lens elements 101 and 102 and/or on the boundary area between the lens elements 102 and 103 so that an end of a strip of flexible material is fastened on a slot of an end-section of a lens element in the same way as shown in figure 1 c. A slot of an end-section 1 19 of the lens element 102 is denoted with a reference number 120 in figure 1 e. It is worth noting that the elongated seal sections can be constituted by only one string of flexible material. This can be the case for example when the string is continuous according to a dash-and-dot line shown in figure 1 c, i.e. there are no ends under the support element 107. In this case, the string is substantially U-shaped if the string has ends under the support element 104 shown in figure 1 a and the string is continuous under the support elements 105 and 106. For another example, the string can be continuous under all the support elements 104-107 in which case the string is ring-shaped.

Each of the support elements 104-107 comprises a sealing section for constituting auxiliary sealing contact areas with at least one of the lens elements 101 -103 and with the body structure 1 14 so that the auxiliary sealing contact areas constitute a substantially ring-shaped sealing contact area that surrounds at least one of the end-sections of the lens elements and those portions of the above-mentioned elongated seal sections 108 and 109 which are in touch with the surrounded at least one end-section. The sealing sections of the support elements 104-107 and the elongated seal sections 108 and 109 are arranged to seal the spatial rooms limited by the lens elements 101 -103 and the body structure 1 14 when the support elements 104-107 are supporting the lens elements so that the lens elements are secured to the body structure 1 14. In the exemplifying optical system illustrated in figures 1 a-1 f, the sealing section of the support element 105 is shaped to consti- tute the substantially ring-shaped sealing contact area with the lens elements 101 and 102 and with the body structure 1 14. Correspondingly, the sealing section of the support element 106 is shaped to constitute the substantially ring-shaped sealing contact area with the lens elements 102 and 103 and with the body structure 1 14. The sealing section of the support element 104 is shaped to constitute the substantially ring-shaped sealing contact area with the lens element 101 and with the body structure 1 14. Correspondingly, the sealing section of the support element 107 is shaped to constitute the substantially ring-shaped sealing contact area with the lens element 103 and with the body structure 1 14. The sealing sec- tions of the support elements 107 and 106 are illustrated below in more details with reference to figures 1 d and 1 f, respectively.

The sealing section of the support element 107 is denoted with a reference number 1 10 in figure 1 d. The sealing section 1 10 comprises a first portion 1 10a for constituting a sealing contact area with the lens element 103 and second portions 1 10b for constituting a sealing contact area with the body structure. As can be seen from figure 1 d, the sealing contact areas related to the first and second portions 1 10a and 1 10b of the sealing section 1 10 constitute the substantially ring- shaped sealing contact area related to the support element 107. It is worth noting that the substantially ring-shaped sealing contact area is not planar, i.e. it is not in a spatial plane.

The sealing section of the support element 106 is denoted with a reference number 1 1 1 in figure 1 f. The sealing section 1 1 1 comprises first portions 1 1 1 a for constituting sealing contact areas with the lens elements 102 and 103 and second portions 1 1 1 b for constituting sealing contact areas with the body structure. As can be seen from figure 1 f, the sealing contact areas related to the first and second portions 1 1 1 a and 1 1 1 b of the sealing section 1 1 1 constitute the substantially ring- shaped sealing contact area related to the support element 106.

In the exemplifying and non-limiting optical system illustrated in figures 1 a-1 f, each of the support elements 104-107 is shaped to form a ridge constituting the sealing section of the support element under consideration. The support elements are ad- vantageously made of flexible material. The flexible material can be for example plastics.

In an optical system according to another exemplifying and non-limiting embodiment of the invention, each of the support elements comprises a strip of flexible material installed on the support element under consideration and constituting the sealing section of the support element. The strip can be for example an O-ring made of e.g. rubber and installed in an appropriately dimensioned groove of the body part of the support element. In this case, the body parts of the support elements can be made of for example plastics or metal. In an optical system according to an exemplifying and non-limiting embodiment of the invention, the sealing section of each of the support elements is coated with a layer of adhesive material capable of adhering to the lens elements and to the external body structure.

In an optical system according to an exemplifying and non-limiting embodiment of the invention, the lens elements or at least the end-sections of the lens elements are similar to each other. For example, as can be seen from figures 1 c-1 f, the end- sections 1 17, 1 18, and 1 19 of the lens elements 102 and 103 are mutually similar. Furthermore, the support elements 105 and 106 are advantageously similar to each other and correspondingly the support elements 104 and 107 are advanta- geously similar to each other. Lens elements and support elements of the kind mentioned above make it possible to construct an optical system having a desired number of lens elements, i.e. there can be one or more lens elements in the optical system.

The above-described principle that the support elements comprise the sealing sec- tions for sealing the end-sections of the lens elements is applicable also in cases where the lens elements are positioned to form geometrical patterns differing from the straight one shown in figures 1 a and 1 b. Figure 2 illustrates an optical system according to an exemplifying and non-limiting embodiment of the invention. The optical system comprises lens elements 201 , 202, and 203, and support elements 204, 205, 206, and 207. The support elements 204, 206, and 207 can be similar to the support elements 104 and 107 shown in figures 1 a and 1 b. The lens elements 201 , 202, and 203 can be similar to the lens elements 101 -103 shown in figures 1 a and 1 b. In figure 2, the elongated seal sections which are between the lens elements and a body structure 214 are depicted with dash-and-dot lines and the sealing sections of the support elements 204-207 are depicted with dashed lines. As can be seen from figure 2, the dash-and-dot lines together with the dashed lines limit a closed area for light sources, e.g. LEDs. In an optical system according to an exemplifying and non-limiting embodiment of the invention, the lens elements are positioned to form a ring. In this exemplifying case, all the support elements are between adjacent lens elements and none of the support elements is such as e.g. the support elements 104 and 107 shown in figures 1 a and 1 b. In an optical system according to an exemplifying and non-limiting embodiment of the invention, the lens elements are positioned to form a ring and one branch connected to the ring. In this exemplifying case, one of the support elements, i.e. the one at the end of the branch, is such as e.g. the support element 104 show in figures 1 a and 1 b. 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. Lists and groups of examples presented above are not exhaustive unless otherwise explicitly stated.