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(11) | EP 4 455 549 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | OPTICAL ELEMENT, LUMINAIRE AND LIGHTING SYSTEM |
| (57) The present invention refers to an optical element (1) for controlling a light distribution
pattern of a light source (13) radiating light beams (L) to a geometric half-space
(H1) being defined by a geometric plane (Pi), wherein the optical element (1) is integrally
made of a transparent piece (2) and comprises a base plate (3) of the transparent
piece (2), a lens section (4) of the transparent piece (2), and a cavity (5) in the
transparent piece (2). The part of the cavity (5) extending through the base plate
(3) defines a bottom cavity space (50) which is circumferentially delimited by a redirection
surface of the transparent piece and continuously tapers towards the lens section.
An angle α of the redirection surface (6), with respect to the geometric plane (P1),
at any part along its circumference is defined such that light propagating through
the base plate (3) by internal total reflection towards the cavity (5) is redirected
at the redirection surface (6) by total internal reflection towards the geometric
half-space (H1) and preferably directly into the lens section (4).
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[0001] The present invention is directed to an optical element for controlling a light distribution pattern of a light source, a luminaire, like a street light or a flood light, comprising said optical element and a light source, and a lighting system comprising the luminaire and a post for carrying the luminaire at a location of operation.
[0002] Usually, light sources emit light over a wide range. However, for many lighting purposes it is required to control the light to be emitted at a defined target area. This can be done by blocking undesired light emission directions. For increase of lighting efficiency, it is known to redirect light being emitted in a non-desired direction to a desired light emission direction. To redirect the light to the desired direction, reflectors can be used. Redirection of light may also be obtained by taking advantage of total internal reflection (TIR); particularly in cases where optical elements like lenses are used for light control.
[0003] There exist luminaires using lenses to emit light in a main (e.g. forward) direction. Such luminaires are, for instance, used as street lights or flood lights which are usually fixed at a raised position, and intended to emit most of the light downwards to the ground below and/or in the vicinity of the luminaire; e.g. at streets, footpaths or sport fields. These luminaires can be positioned at or around sensitive areas (e.g. as houses, habitations, environmental zones, etc.), which are in the vicinity of the target area but should not be affected by the illumination.
[0004] There exist integral optical lens elements 100, which comprise a panel-like base plate 103 on which one or a plurality of lenses 104 are arranged. FIG. 1-4 show an example of such a conventional optical element 100. The optical element 100 comprises a cavity 105 (either with a single or a plurality - e.g. two - cavity sections) at the respective lenses 104 to receive a light source 113 for emitting light to be controlled by the lens 104 when passing through the lens 104 to allow light emission (see, e.g., arrow L100) within a desired primary beam limit, as indicated by dashed lines in FIG. 4. The common base plate 103 of such optical elements 100 may allow stray light (see, e.g., arrow L200) to propagate through the optical element 100. The stray light may originate from the light source 113, as shown in the example of FIG. 4, and/or it may originate from other sources of the luminaire 110 or even from outside the luminaire 110.
[0005] There exist methods to block any undesired (stray) light, e.g. propagating through the base plate- Such methods include, for instance, internal or external louvers, masks, grids and the like. However, for optical elements 100 as shown in the example of FIG. 1-4, as the stray light may propagate through the base plate 103 which carries the lenses 104, the stray light may reach other lenses via this path. There, the stray light may be undesirably controlled by the lens 104, and thus may exit the lens 104 in an undesired direction (see, e.g., arrow L300); which means, for instance, outside the desired primary beam limit. Hence, the stray light may reach the mentioned sensitive areas, thus having a disturbing effect. As the lenses 104 are indeed intended for controlled light emission of the light source 113 associated thereto, it is difficult to block the unwanted light beams as this may also affect the primary beam and the desired lighting characteristic of the luminaire 110.
[0006] FIG. 1 shows a perspective view of a conventional lens design. As can be seen, a bottom space 150 of the cavity 105 being defined - i.e. surrounded - by the base plate 103 has a circumferential border area 106, wherein at least parts of which are oriented substantially vertical (see FIGs. 2-4). FIGs. 2 and 3 show a side view and a front view of the conventional lens design and a potential propagation direction of stray light beams propagating through the base plate 103 of the lens element 100 towards the cavity 105. FIG. 4 shows the direction of the stray light beams through and out of the lens element 100 (see, e.g., arrows L200 and L300). As can be seen, the stray light beam coming from the base plate 103 reaches the vertical border area 106, enters the cavity 105 via the vertical border area 106, exits the cavity 105 at a top section thereof, reaches the outer surface of the lens 104, and exits the lens 104 such that it emits in a direction reaching outside the desired primary beam limit. Even though methods for controlling the light exiting the lens element 100 may be provided, they may not or can only hardly control stray light which exits the lens 104 itself. Some of the referred methods (e.g. internal louvers) do aim at controlling the light exiting the lens 104 itself, not only the optical element 100 in general. The internal louver blocks light mainly at the borders of the desired primary beam limit (i.e. close to the dashed lines), but cannot or not effectively block stray light beams exiting at the center of the lens 104 (i.e. between and distant to the dashed lines; as indicated by arrow L300) without also affecting the primary beam. In order not to affect the primary beam or to affect it less, stray light beams (as exemplarily indicated by arrow L300) need to be blocked further away from the optical element 100, e.g. with an external accessory (e.g. a visor), which will affect the luminaire in many ways (e.g. increased costs, increased dimensions, increased weight, increased wind drag area, increased weight, etc.), while not always being effective. Hence, control or elimination of such stray light becomes difficult, thus potentially resulting in light reaching sensitive areas outside the target area or decreasing efficiency of the luminaire.
[0007] It is thus an object of the present invention to provide an optical element as well as a luminaire and a lighting system being equipped with said optical element, which allow for an accurate control of a light distribution pattern and effective light emission to a target area, while preferably reducing the influence of stray light to obtain (sensitive) areas around the target area or luminaire be less affected.
[0008] These and other objects, which will come apparent upon reading the description, are solved by the subject-matter of the independent claims. The dependent claims study further central idea of the present invention.
[0009] According to a first aspect the present invention is directed to an optical (lens) element for controlling a light distribution pattern of a light source radiating light beams to a geometric half-space being defined by a geometric plane. The optical element is integrally made of a transparent piece (e.g., a transparent one-piece). The optical element comprises a base plate of the transparent piece, a lens section of the transparent piece, and a cavity in the transparent piece. The base plate being a light guide panel. The base plate has a front face extending in the geometric plane and a rear face extending parallel to the front face at a side of the geometric plane being opposite to the geometric half-space. The lens section bulges from the front face towards and into the geometric half-space. The cavity extends through the base plate from the rear face towards the lens section into the geometric half-space so that the lens section - at least partially and preferably completely - borders the cavity in the geometric half-space. The cavity is thus preferably formed as a recess or a blind hole in the transparent piece. The cavity defines a circumferential opening at the rear face for receiving (at least part of) the light source in the cavity. The lens section is configured to control the light distribution pattern of the light source (at least partly) received in the cavity to exit into the geometric half-space; preferably in a predefined manner. The part of the cavity extending (i.e. over the entire height) between the rear face and the front face defines a bottom cavity space which is circumferentially (i.e. circumferentially closed) delimited by a redirection surface of the transparent piece and tapers from the rear face to the front face (i.e. it continuously tapers; which means over its entire height between the rear face and the front face). The bottom cavity space thus tapers over its entire height from the rear face towards the lens section or the geometric half-space. When viewed along the geometric plane, an angle α of the redirection surface, with respect to the geometric plane, at any part along its circumference is defined such that light propagating through the base plate by internal total reflection (TIR; e.g. single or multiple TIR) towards the cavity is redirected at the redirection surface by total internal reflection (TIR) towards the geometric half-space.
[0010] The main function of the base plate is mechanical to hold the one or more lens sections. Due to it being integral with the lens section(s) as part of the transparent piece results in the somewhat undesired function of the base plate acting as a light guide panel and thus potentially further resulting in undesired stray light propagation. The flared circumferential redirection surface surrounding or defining the bottom cavity space of the cavity, as it is angled all around its circumference over its entire height, allows for a predefined control (i.e. redirection) of such light (e.g. stray light) propagating through the base plate by total internal reflection, and thus preferably reducing or avoiding its influence on the overall lighting characteristic of the luminaire, which shall preferably be mainly or only dictated or defined by the lens section(s). The light can thus be (redirected in a way that it can be more effectively controlled (e.g. redirected, absorbed, etc.) in any desired way. For instance, the light can be redirected to sections of the optical element, which allow for an effective blocking of the stray light (without affecting the primary beam or the desired lighting characteristic of the luminaire) or which allow for a controlled exit of the stray light to stay within the predefined primary beam limit of the lens section. Preferably, the light can thus be (re-)directed in a way that it avoids the cavity for increased control of the undesired (stray) light. The angle α can be constant or not constant around the circumference of the redirection surface and/or along its extension between the rear face and the front face, as long as it allows for the redirection surface to function by TIR as described. As the redirection surface is provided in a zone of the optical element having no or at most limited influence on the intended light control of the optical element, the redirection surface can be designed as desired for an effective light control. This allows to reduce or even eliminate undesired (stray) light and eventually reduce nuisance, e.g. at sensitive areas around the desired target area for illumination, to a minimum - when combined with other conventional methods - by means of a simple and easy to implement functional design feature. As the redirection surface is part of the integral transparent piece, it can be simply provided during the initial development and production of the optical element. Hence, the light control of the optical element can be provided during the production of the optical element, and thus requires no additional costs compared to alternative solutions based on additional components, such as external accessories. As mentioned, a variety of shapes of the flared zone (i.e. the redirection surface) can be provided to adapt to a variety of lens shapes and light distribution characteristics as found in any desired lighting application.
[0011] The lens section may be configured to control the light distribution pattern of the light source (at least partly) received in the cavity to exit into the geometric half-space within a (e.g. desired or predefined) primary beam limit. When viewed along the geometric plane, the angle α of the redirection surface, with respect to the geometric plane, at any part along its circumference may then preferably be defined such that (at least part of) the light propagating through the base plate by internal total reflection towards the cavity is redirected at the redirection surface by total internal reflection towards the geometric half-space to avoid the cavity and/or to exit the lens section in a way to remain within the primary beam limit. This allows for a defined control of light and potentially an increased lighting efficiency.
[0012] When viewed along the geometric plane, the angle α of the redirection surface, with respect to the geometric plane, at any part along its circumference may preferably be defined such that the light propagating through the base plate by internal total reflection towards the cavity is redirected at the redirection surface by total internal reflection towards the geometric half-space to avoid the cavity. This facilitates control of such (stray) light, as desired.
[0013] When viewed along the geometric plane, the angle α of the redirection surface, with respect to the geometric plane, at any part along its circumference may preferably be defined such that the light propagating through the base plate by internal total reflection towards the cavity is redirected at the redirection surface by total internal reflection towards the geometric half-space and directly (i.e. without leaving the transparent piece) into the lens section. The light can thus be controlled to be (re-)directed into the lens section, where it can be further controlled in any desired way.
[0014] The lens section may be configured such that at least part of the light redirected at the redirection surface is redirected to exit the lens section towards the side of the geometric plane being opposite to the geometric half-space or to exit at the rear face. It is thus possible to effectively redirect any undesired light coming from the base plate towards the cavity or lens section in a manner that it does not exit the lens section. Hence, the undesired light can be effectively eliminated from being emitted via the lens section. Hence, influence of undesired light at sensitive areas around the target area can be effectively reduced, minimized or even eliminated.
[0015] The lens section may be configured such that the at least part of the light is redirected at a border surface of the lens section defining at least part of the outer surface of the lens section and/or defining at least part of the cavity. Hence, a redirection function of the lens section can be integrated in the transparent piece for an effective light redirection. Production of the optical element can thus be facilitated, number of pieces be reduced, and light control be easily improved.
[0016] The angle α may be defined in a range between 20° and 70°, preferably between 30° and 60°, more preferred at (around/substantially) 45°. The given ranges can be selected to define the flare shape of the redirection surface as desired for effectively generating total internal reflection of light coming from the base plate towards the cavity. The term "defined in a range" means that the angle α can be constant or not constant around the circumference of the redirection surface and/or along its extension between the rear face and the front face.
[0017] The lens section may be configured such that the light distribution pattern of the light source (at least partly) received in the cavity can be controlled such that the majority (i.e. most or all) of the light beams of the light source (at least partly) received therein are radiated to a first geometric quarter-space of the geometric half-space. The first geometric quarter-space is defined by a second geometric plane being perpendicular to the geometric plane constituting a boundary between the first geometric quarter-space and a second geometric quarter-space of the geometric half-space. Such a lens design allows for a defined light emission direction to a particular geometric quarter-space. This is particularly desired for applications to illuminate, e.g., streets, footpaths or sports arenas and the like.
[0018] The optical element may comprise a plurality of the lens sections with corresponding cavities (i.e. every lens section is associated with its own cavity). Hence, the efficiency of the optical element can be increased. The use of a plurality of such lens sections including cavities may result in unwanted stray light propagating through the base plate from the light source (at least partly) received in one of the cavities to other (neighboring) cavities. However, due to the flared bottom cavity space and redirection surface, such stray light can be effectively reduced or even eliminated within the system itself, as described.
[0019] The plurality of the lens sections may preferably be arranged as a lens array. The plurality of the lens sections may preferably be arranged in at least one row or a plurality of rows and/or in a matrix. Hence, the plurality of lens sections may be arranged in any desired way for providing a most effective optical element, as desired.
[0020] The transparent piece may be a one-piece element. Hence, the optical element can be easily produced at comparably low costs, and its handling is made easy.
[0021] The transparent piece may preferably be made of one of the following: acrylic plastic, polycarbonate, optical silicone, glass, or combinations thereof. These materials allow for an accurate light control, light passing, and a long-term use.
[0022] The redirection surface may comprise a surface structure for improving the light redirection control, as desired.
[0023] According to a further aspect, the present invention is directed to a luminaire, like a street light or a flood light, comprising an optical element according to the present invention as well as a light source being (at least partly) received in the cavity or at least positioned to emit light into the cavity for a desired control of the light distribution pattern. Hence, a luminaire can be easily provided in which light emitted by the light source can be easily controlled to allow for obtaining/controlling a desired light distribution pattern with improved stray light control, as described. The advantages of the optical element, as described, can thus be applied to a luminaire equipped therewith.
[0024] The light source can be a light emitting diode (LED). LEDs have small dimensions, high light output and can efficiently be operated.
[0025] The luminaire may further comprise an LED-module with a printed circuit board and an LED (i.e. one or a plurality of LEDs) as the light source being provided on the printed circuit board (PCB). Hence, a luminaire can be provided in a most compact manner, which can be easily handled.
[0026] The optical element may preferably be attached, more preferred with its rear face, to part of the LED-module, preferably to the printed circuit board. Hence, the luminaire can be provided in a compact manner. Also, the light can be effectively coupled into the optical element, as desired.
[0027] The LED-module or its printed circuit board may preferably comprise a light absorbing surface facing towards the optical element to absorb at least part of light exiting the rear of the optical element and preferably exiting the optical element at the rear face of the base plate. The light absorbing surface may be a separate element provided on the printed circuit board, or it can be a dark/black coating or printing on the printed circuit board, or the like. By means of the light absorbing surface, any unwanted light exiting the optical element at its rear side can be effectively eliminated. In particular, in case the unwanted light is the light that comes from the base plate towards the cavity, and is redirected via the redirection surface in a way to exit the rear side of the optical element, this unwanted light can be highly effectively reduced or eliminated.
[0028] The luminaire may further comprise a light blocking means. The light blocking means are positioned in the geometric half-space to block at least part of the light exiting the optical element. The light blocking means may preferably comprise at least one of the following: an internal louver, an external louver, a mask element, a mask coating or printing, a grid, and any combinations thereof. Hence, the optical element can be equipped with any desired means to further improve controlling of the light distribution pattern and light emission characteristic. Hence, undesired light emission directions may be cut-off, thus improving an effective illumination of the target area.
[0029] According to a further aspect, the present invention is directed to a lighting system comprising a luminaire according to the present invention as well as a post, like a pole, for carrying the luminaire at the location of operation; preferably at a raised position, as desired. This preferably such that the luminaire is oriented with the geometric plane in a horizontal and the geometric half-space preferable facing downwards. Even more preferred, when the luminaire comprises an optical element with a lens section being configured to control light emission to radiate towards the first geometric quarter-space, the post carries the luminaire such that the first geometric quarter-space is directed away from a vertical section of the post. With such a lighting system, the luminaire can be easily provided at any required location of operation, and preferably at any desired raised level over the ground. Also, the light distribution pattern may be controlled such that the light emission can be effectively focussed on the target area while reducing nuisance at any sensitive area in the surrounding of the target area or in the surrounding of the lighting system. Moreover, the light distribution pattern may be controlled such that light emission is mainly directed away from a post of the lighting system to thus allow for a most efficient light emission, as desired.
[0030] Further features, advantages and objects of the present invention will become apparent for the skilled person when reading the following detailed description of the embodiments of the invention and when taking in conjunction with the figures of the enclosed drawings.
- FIG. 1
- shows a perspective top view of an optical element according to the prior art,
- FIG. 2
- shows a side view of the optical element of FIG. 1,
- FIG. 3
- shows a front view of the optical element according to FIG. 1,
- FIG. 4
- shows a schematic side view of an optical element according to the prior art having two lens sections and corresponding cavities as the ones of the optical element according to FIG. 1 as well as a light path of a light beam for desired light emission as well as a light path of an undesired light beam propagating through the base plate,
- FIG. 5
- shows a perspective top view of an optical element according to a first embodiment of the present invention,
- FIG. 6
- shows a side view of the optical element according to FIG. 5,
- FIG. 7
- shows a front view of the optical element according to FIG. 5,
- FIG. 8
- shows a schematic side view of an optical element according to a second embodiment of the present invention having two lens sections and corresponding cavities as the ones of the optical element according to FIG. 5 as well as a light path of a light beam for desired light emission as well as a light path of an undesired light beam propagating through the base plate, and
- FIG. 9
- shows a perspective top view of an optical element according to a third embodiment of the present invention.
[0031] FIGs. 5-9 show different embodiments of an optical element 1 according to the present invention. The optical element 1 preferably is a lens or a lens plate, as will be described in more detail herein below. The optical element 1 is integrally made of a transparent piece 2. The transparent piece 2 can be a one-piece element. The transparent piece 2 can be made of acrylic plastic, polycarbonate, optical silicone, glass, or combinations thereof.
[0032] The optical element 1 is provided for controlling a light distribution pattern of a light source 13 radiating light beams L to a geometric half-space H1 being defined by a geometric plane P1, as exemplarily shown in FIGs. 6-8.
[0033] The optical element 1 comprises a base plate 3 of the transparent piece as can be seen in FIGs. 5-9. As can be particularly seen in FIGs. 6-8, the base plate 3 can be a light guide panel; which means that the base plate 3 has light guide panel functions by having such dimensions to allow light beams propagating along the extension direction of the base plate 3 by total internal reflection (TIR).
[0034] As can also be seen in FIGs. 6-8, the base plate 3 has a front face 30 extending in the geometric plane P1 and a rear face 31 extending parallel to the front face 30 at a side H2 of the geometric plane P1 being opposite to the geometric half-space H1. Said opposite side H2 thus forms the other geometric half-space H2 of the space divided by the geometric plane P1.
[0035] The optical element 1 further comprises a lens section 4 of the transparent piece 2 bulging from the front face 30 towards and into the geometric half-space H1, as exemplarily shown in FIGs. 6-8.
[0036] The optical element 1 further comprises a cavity 5 in the transparent piece 2, as exemplarily shown in FIGs. 5-9.
[0037] The cavity 5 extends through the base plate 3 from the rear face 31 towards the lens section 4 into the geometric half-space H1 so that the lens section 4 at least partially and here completely borders the cavity 5 in the geometric half-space H1 (see FIG. 6-8).
[0038] As can be seen in FIG. 6-8 and also derived from FIG. 5 and 9, the cavity 5 defines a circumferential opening 51 at the rear face 31 for receiving (at least part of) the light source 13 in the cavity 5. In the shown embodiment, the cavity 5 is formed as a recess or blind hole in the transparent piece 2, which recess or blind hole is open at the rear face 31, and through which the cavity 5 can be entered by a corresponding light source 13 (see FIG. 8).
[0039] The lens section 4 is configured to control the light distribution pattern of the light source (at least partly) received in the cavity 5 to exit into the geometric half-space H1, here in a predefined manner. This is exemplarily shown by arrow L1 showing an exemplary light beam originated from the light source 13, passing through the lens section 4, and exiting the lens section 4 towards and into the geometric half-space H1 to emit within a predefined primary beam limit, which is here indicated by dashed lines and exemplarily representing the light distribution pattern.
[0040] The respective lens section 4 may be configured such that the light distribution pattern of the light source 13 (at least partly) received in the cavity 5 is controlled such that the majority of the light beams of the light source (at least partly) received therein are radiated to a first geometric quarter-space Q1 of the geometric half-space H1. The first geometric quarter-space Q1 is defined by a second geometric plane P2 being perpendicular to the geometric plane P1 constituting a boundary between the first geometric quarter-space Q1 and a second geometric quarter-space Q2 of the geometric half-space H1 (see, e.g., FIG. 6 and 8). Here, the second geometric plane P2 divides the respective cavity 5 into two halves. The cavity 5 as well as the lens section 4 may be symmetrical with respect to the second geometric plane P2 and/or a third geometric plane P3 being perpendicular to both the first geometrical plane P1 and the second geometric plane P2. According to the present embodiments, as exemplarily derivable from FIG 7, the cavity 5 as well as the lens section 4 are here symmetrical at least with respect to the third geometric plane P3.
[0041] Each of the lens sections 4 and corresponding cavities 5 is associated with a respective geometric half space H1 and other geometric half space H2, a first and second quarter space Q1, Q2 as well as a first to third geometric plane P1-P3, whereas the first plane P1 and the half spaces H1 and H2 are here identical to all lens sections 4 and corresponding cavities 5.
[0042] The part of the cavity 5 extending over the entire height between the rear face 31 (i.e. starting at the circumferential opening 51) and the front face 30 defines a bottom cavity space 50 which is circumferentially delimited by a redirection surface 6 of the transparent piece 2. The bottom cavity space 50 or likewise the redirection surface 6 taper(s) from the rear face 31 to the front face 30. Hence, the bottom cavity space 50 or likewise the redirection surface 6 continuously taper(s) over the entire height D of the bottom cavity space 50; which means over its entire height between the rear face 31 and the front face 30. The bottom cavity space 50 thus tapers over its entire height D from the rear face 31, starting at the circumferential opening 51, towards the lens section 4 or the geometric half-space H1. As can be derived from FIGs. 5-8, when viewed along the geometric plane P1, an angle α of the redirection surface 6, with respect to the geometric plane P1, at any part along its circumference is defined such that light propagating through the base plate 3 by internal total reflection (e.g. single or multiple TIR) towards the cavity 5 (indicated by arrow L2) is redirected at the redirection surface 6 by total internal reflection towards the geometric half-space H1 and preferably directly into the lens section 4, as indicated by arrow L3. FIG. 8 exemplarily shows a path of such a light beam propagation. As also derivable from Fig. 8, it is preferably desired to redirect the light at the redirection surface 6 by total internal reflection towards the geometric half-space H1 to avoid the cavity 5 and/or to exit the lens section 4 in a way to remain within the primary beam limit exemplarily indicated by dashed lines in Fig. 8.
[0043] The angle α can be defined in a range between 20° and 70°, preferably between 30° and 60°, more preferred at around 45°.
[0044] As can also be derived from FIG. 8, the lens section 4 may be configured such that at least part of the light redirected at the redirection surface 6is redirected to exit the lens section 4 towards the side H2 of the geometric plane P1 being opposite to the geometric half-space H1 or to exit at the rear face 31; i.e. at the rear of the optical element 1. This is exemplarily indicated by arrow L4 in FIG. 8.
[0045] As can also be derived from FIG. 8, the lens section 4 may be configured such that the at least part of the light can be redirected at a border surface 40 of the lens section 4 defining at least part of the outer surface of the lens section 4 and/or defining at least part of the cavity 5.
[0046] As is exemplarily shown in FIG. 9, the optical element may comprise a plurality of the lens sections 4 with corresponding cavities 5; i.e. each lens section 4 is associated with a cavity 5. The plurality of the lens sections 4 may then be arranged as a lens array, as exemplarily shown in FIG. 9. The plurality of the lens sections 4 can be arranged in at least one row (in FIG. 9 there are shown two rows) and/or in a matrix.
[0047] With particular reference to FIG. 8, a luminaire 10, like a street light or a flood light, may be provided comprising an optical element 1 according to the present invention and as described in detail herein above. The luminaire 10 further comprises a light source 13. As shown in FIG. 8, the light source 13 can preferably be (at least partly) received in the cavity or at least positioned to emit light into the cavity 5; i.e. provided so as to emit/radiate the light beams via the lens section 4 to obtain the desired light distribution pattern. The light source 13 may be an LED.
[0048] The luminaire 10 may comprise an LED-module 11 comprising a printed circuit board 12 and an LED as the light source 13 being provided on the printed circuit board 12, as exemplarily shown in FIG. 8.
[0049] The optical element 1 may preferably be attached to part of the LED-module 11, preferably to the printed circuit board 12. In a preferred embodiment, the optical element 1 can be attached with or via its rear face 31.
[0050] The LED-module 11 or its printed circuit board 12 may comprise a light absorbing surface 14 facing towards the optical element 1 to absorb at least part of light exiting the rear of the optical element 1 preferably at the rear face 31 of the base plate 3. For instance, the light absorbing surface 14 can be a dark or black printing or coating on the printed circuit board.
[0051] The luminaire 10 may further comprise a light blocking means (not shown). The light blocking means are preferably positioned at least in the geometric half-space H1 to block part of the light exiting the optical element 1; preferably at least at the front of the optical element 1. The light blocking means may preferably comprise at least one of the following: an internal louver, an external louver, a mask element, a mask coating or printing, a grid, and any combination thereof.
[0052] The luminaire 10 may further comprise additional features and accessories, as desired and known in the art.
[0053] The present invention is further directed to a lighting system comprising the luminaire 10 according to the present invention and as well described in detail herein above. The lighting system further comprises a post, like a pole, for carrying the luminaire 10 at a location of operation. The pole is preferably configured such that the luminaire 10 is oriented with the geometric plane P1 in horizontal and the geometric half-space H1 preferably facing downwards. Such an application can, for instance, be used as a street light or as a flood light for a sports arena, or the like.
[0054] In case of the optical element 1 having a lens section 4 being configured to radiate light to the first geometric quarter-space Q1, the pole may further be configured such that it carries the luminaire 10 in a way that the first geometric quarter-space Q1 is directed away from a vertical section of the post, to allow for an effective and desired lighting characteristic.
1. An optical element (1) for controlling a light distribution pattern of a light source
(13) radiating light beams (L) to a geometric half-space (H1) being defined by a geometric
plane (P1), wherein the optical element (1) is integrally made of a transparent piece
(2) and comprises:
• a base plate (3) of the transparent piece (2), the base plate (3) being a light guide panel and having a front face (30) extending in the geometric plane (P1) and a rear face (31) extending parallel to the front face (30) at a side of the geometric plane (P1) being opposite to the geometric half-space (H1),
• a lens section (4) of the transparent piece (2) bulging from the front face (30) towards and into the geometric half-space (H1), and
• a cavity (5) in the transparent piece (2), the cavity (5) extending through the base plate (3) from the rear face (31) towards the lens section (4) into the geometric half-space (H1) so that the lens section (4) borders the cavity (5) in the geometric half-space (H1), wherein the cavity (5) defines a circumferential opening (51) at the rear face (31) for receiving the light source (13) in the cavity (5), and wherein the lens section (4) is configured to control the light distribution pattern of the light source (13) received in the cavity (5) to exit into the geometric half-space (H1),
wherein the part of the cavity (5) extending between the rear face (31) and the front face (30) defines a bottom cavity space (50) which is circumferentially delimited by a redirection surface (6) of the transparent piece (2) and continuously tapers from the rear face (31) to the front face (30), wherein, when viewed along the geometric plane (P1), an angle α of the redirection surface (6), with respect to the geometric plane (P1), at any part along its circumference is defined such that light propagating through the base plate (3) by internal total reflection towards the cavity (5) is redirected at the redirection surface (6) by total internal reflection towards the geometric half-space (H1).2. The optical element (1) according to claim 1, wherein, when viewed along the geometric
plane (P1), the angle α of the redirection surface (6), with respect to the geometric
plane (P1), at any part along its circumference is defined such that the light propagating
through the base plate (3) by internal total reflection towards the cavity (5) is
redirected at the redirection surface (6) by total internal reflection towards the
geometric half-space (H1) and directly into the lens section (4).
3. The optical element (1) according to claim 1 or 2, wherein the lens section (4) is
configured such that at least part of the light redirected at the redirection surface
(6) is redirected to exit the lens section (4) towards the side (H2) of the geometric
plane (P1) being opposite to the geometric half-space (H1) or to exit at the rear
face (31).
4. The optical element (1) according to claim 3, wherein the lens section (4) is configured
such that the at least part of the light is redirected at a border surface (40) of
the lens section (4) defining at least part of the outer surface of the lens section
(4) and/or defining at least part of the cavity (5).
5. The optical element (1) according to any one of the preceding claims, wherein the
angle α is defined in a range between 20° and 70°, preferably between 30° and 60°,
more preferred at around 45°.
6. The optical element (1) according to any one of the preceding claims, wherein the
lens section (4) is configured such that the light distribution pattern of the light
source (13) received in the cavity (5) is controlled such that the majority of the
light beams (L) of the light source (13) received therein are radiated to a first
geometric quarter-space (Q1) of the geometric half-space (H1), wherein the first geometric
quarter-space (Q1) is defined by a second geometric plane (P2) being perpendicular
to the geometric plane (P1) constituting a boundary between the first geometric quarter-space
(Q1) and a second geometric quarter-space (Q2) of the geometric half-space (H1).
7. The optical element (1) according to any one of the preceding claims, wherein the
optical element (1) comprises a plurality of the lens sections (4) each with associated
cavity (5).
8. The optical element (1) according to claim 7, wherein the plurality of the lens sections
(4) are arranged as a lens array, and/or
wherein the plurality of the lens sections (4) are arranged in at least one row and/or in a matrix.
wherein the plurality of the lens sections (4) are arranged in at least one row and/or in a matrix.
9. The optical element (1) according to any one of the preceding claims, wherein the
transparent piece (2) is a one-piece element, and/or
wherein the transparent piece (2) is made of one of the following: acrylic plastic, polycarbonate, optical silicone, glass, or combinations thereof.
wherein the transparent piece (2) is made of one of the following: acrylic plastic, polycarbonate, optical silicone, glass, or combinations thereof.
10. A luminaire (10), like a street light or a flood light, comprising an optical element
(1) according to any one of the preceding claims and a light source (13) being received
in the cavity (5).
11. The luminaire (10) according to claim 10, further comprising an LED-module (11) with
a printed circuit board (12) and an LED as the light source (13) being provided on
the printed circuit board (12).
12. The luminaire (10) according to claim 10 or 11, wherein the optical element (1) is
attached, preferably with its rear face (31), to part of the LED-module (11), preferably
to the printed circuit board (12).
13. The luminaire (10) according to claim 11 or 12, wherein the LED-module (11) or its
printed circuit board (12) comprises a light absorbing surface (14) facing towards
the optical element (1) to absorb at least part of light exiting the rear of the optical
element (1) preferably at the rear face (31) of the base plate (3).
14. The luminaire (10) according to any one of claims 10 to 13, further comprising a light
blocking means positioned in the geometric half-space (H1) to block part of the light
exiting the optical element (1), wherein the light blocking means preferably comprises
at least one of the following: an internal louver, an external louver, a mask element,
a mask coating or printing, a grid, and any combinations thereof.
15. A lighting system comprising a luminaire (10) according to any one of claims 10 to
14 as well as a post, like a pole, for carrying the luminaire (10) at a location of
operation, preferably such that the luminaire (10) is oriented with the geometric
plane (P1) in a horizontal and the geometric half-space (H1) preferably facing downwards,
and preferably, when the luminaire (10) comprises an optical element (1) according
to claim 6, such that the first geometric quarter-space (Q1) is directed away from
a vertical section of the post.