WO2001002771A1

WO2001002771A1 - Luminaire and signaling lamp

Info

Publication number: WO2001002771A1
Application number: PCT/EP2000/006038
Authority: WO
Inventors: Matthijs H. Keuper; Albertus J. H. M. Kock
Original assignee: Lumileds Lighting B.V.
Priority date: 1999-07-02
Filing date: 2000-06-28
Publication date: 2001-01-11
Also published as: JP2003503827A; TW567449B; EP1110027A1

Abstract

A luminaire comprises a housing (2) with a light emission window (3). The housing (2) accommodates a plurality of opto-electronic elements (5, 5', ...; 6, 6', ...; 7, 7', ...) and a plurality of collimating elements (15; 16; 17). In operation, the opto-electronic elements (5, 5', ...; 6, 6', ...; 7, 7', ...) emit visible light. Each of the collimating elements (15; 16; 17) has an optical axis (25; 26; 27) and is associated with an opto-electronic element (5, 5', ...; 6, 6', ...; 7, 7', ...). According to the invention, the opto-electronic element (5; 6; 7) is positioned substantially eccentrically with respect to the optical axis (25; 26; 27) of the collimating element (15; 16; 17) with which the opto-electronic element (5; 6; 7) is associated. Preferably, at least one further opto-electronic element (5'; 6'; 7') is associated with at least one collimating element (15; 16; 17). Said further opto-electronic element (5'; 6'; 7') is either positioned substantially eccentrically or coincides with the optical axis (25; 26; 27) of the collimating element (15; 16; 17) with which the further opto-electronic element (5'; 6'; 7') is associated. Preferably, the optical axes (25; 26; 27) of the collimating elements (15; 16; 17) are directed so as to be substantially parallel to each other. Preferably, the collimating elements (15; 16; 17) are Fresnel lenses and the opto-electronic elements (5, 5', ...; 6, 6', ...; 7, 7', ...) are light-emitting diodes.

Description

Luminaire and signaling lamp.

The invention relates to a luminaire comprising a housing having a light emission window, wherein the housing accommodates a plurality of opto-electronic elements and a plurality of collimating elements, wherein, in operation, the opto-electronic elements emit visible light, and wherein each of the collimating elements has an optical axis and is associated with an opto-electronic element.

The invention also relates to a signaling lamp provided with a luminaire.

Such luminaires are known per se. They are used, inter alia, in signal lighting to control different types of traffic, such as traffic lights. Luminaires of this type comprise a relatively large number of opto-electronic elements, also referred to as electro-optical elements, for example electroluminescent elements, such as light-emitting diodes (LEDs). These light sources are generally distributed in accordance with a certain regular pattern over an inner surface of the housing. The collimating elements, for example positive lenses, such as Fresnel lenses, provide for a proper light-intensity distribution and, if necessary, a homogeneous brightness distribution. It is noted that "light intensity distribution" is to be taken to mean the angle-dependent light intensity distribution. "Brightness distribution" is to be taken to mean the angle-independent light distribution on the surface of the light emission window of the luminaire. US-A 5 816 681 describes how the collimating elements can be structured in such a way that an opto-electronic element is associated with each one of the collimating elements. By virtue of the presence of collimating elements, the brightness distribution of the light emission window of the luminaire is at least substantially homogeneous in operation.

Luminaires and signaling lamps of the type described hereinabove have an important drawback. If it is not desired to illuminate the entire light emission window, for example because a mask covers a part of the light emission window, the part of the light which is incident on the covered part of the light emission window is lost, leading to a reduction of the light output of the luminaire, which is undesirable. It is an object of the invention to obviate the above-mentioned drawback. The invention more particularly aims at providing a luminaire of the type mentioned in the opening paragraph, wherein a relatively high light output is obtained also if inhomogeneous lighting at the location of the light emission window is desired. To achieve this, the luminaire is characterized in accordance with the invention in that the opto-electronic element is arranged essentially eccentrically with respect to the optical axis of the collimating element with which the opto-electronic element is associated. By arranging the opto-electronic element so as to be essentially off the optical axis of the associated collimating element, the ray path of the opto-electronic element's light beam issuing from the collimating element is changed. By virtue thereof, it is achieved that instead of the entire light emission window, only a desired part thereof is illuminated. A signaling lamp, for example a traffic light, may be used for different lighting purposes. For example, it may be desirable to homogeneously illuminate the entire surface of the light emission window of the luminaire by means of a light beam of a desired color, for example red, yellow or green. In another embodiment of the signaling lamp, a part of the light emission window is provided with a mask or other means which obstruct the passage of light, the luminaire showing, in operation, for example an illuminated arrow or an illuminated image of a pedestrian in a desired color. Examples hereof include signaling lamps comprising one or more illuminated, colored arrows for traffic turning right or left, or signaling lamps comprising a stationary pedestrian showing red, or a (seemingly) walking pedestrian showing green. The blinded part of the light emission window does not emit light. In accordance with the invention, the opto-electronic element is eccentrically arranged with respect to the optical axis of the collimating element in order to make sure that only the desired part of the light emission window is illuminated. The blinded part of the light emission window may comprise more than 80% of the surface of the light emission window. In the known luminaire, the opto-electronic element is situated on the optical axis of the optoelectronic element, so that an integral and homogeneous illumination of the light emission window is obtained. In the known luminaire, the passage of, for example, only 15% of the light through the light emission window leads to a considerable loss of light output. If, in accordance with the invention, only the desired parts of the light emission window are irradiated, the cost of the opto-electronic elements and the cost of energy consumption are reduced considerably.

In the known luminaire, a light-emitting diode (LED) is associated with a Fresnel lens (collimating element), said LED being positioned on the optical axis of the Fresnel lens. If the LED is arranged in the focus of the Fresnel lens, said Fresnel lens emits a substantially parallel light beam which extends along the optical axis of the Fresnel lens.

In the luminaire in accordance with the invention, the opto-electronic element is essentially positioned off the optical axis of the collimating element with which the opto- electronic element is associated. If the opto-electronic element is a LED and the collimating element is a (positive) Fresnel lens, said Fresnel lens emits a substantially parallel light beam with a specific aperture angle if the LED is arranged at a distance from the Fresnel lens which is equal to the focal distance of the Fresnel lens. If the LED is arranged at a distance greater or smaller than the focal distance of the Fresnel lens, then said Fresnel lens emits a converging or diverging light beam with a specific solid angle. Such light beams are alternatively referred to as pre-directed light beams.

An embodiment of the luminaire is characterized in accordance with the invention in that with at least one collimating element at least one further opto-electronic element is associated. In the known luminaire, each of the collimating elements is associated with a single light source which is situated on the optical axis of the associated collimating element. By arranging two or more opto-electronic elements per collimating element in the housing of the luminaire, the light output of the luminaire is further increased. The use of one optoelectronic element per collimating element enables the light beam emitted by the collimating element to be directed, while the use of two or more opto-electronic elements per collimating element enables the light beam emitted by the collimating element to be directed as well as shaped into a specific form.

A luminaire in accordance with the invention wherein a plurality of optoelectronic elements is associated with each collimating element has the advantage that such a luminaire uses the available light much more efficiently. A suitable, predeterminable

(eccentric) positioning of the opto-electronic elements with respect to the optical axes of the associated collimating elements enables the uncovered parts of the light emission window to be efficiently illuminated by placing opto-electronic elements and collimating elements only behind the parts of the light emission window to be illuminated. In addition, failure of one or more opto-electronic elements is not, or hardly, observable. In the known luminaire, failure of one of the opto-electronic elements causes a dark spot on the light emission window, which is undesirable. An additional advantage of the luminaire in accordance with the invention is that a higher light output of the opto-electronic elements, for example because more efficient optoelectronic elements become available in the future, the number of opto-electronic elements per collimating element can be reduced without an adaptation of the internal optical structure of the luminaire being necessary. In the known luminaire, a reduction of the number of optoelectronic elements necessitates redesigning the optical structure. A further advantage of the luminaire in accordance with the invention resides in that such a luminaire is less sensitive to aligning errors. In the known luminaire, opto-electronic elements which are misaligned are immediately visible.

The suitable (eccentric) positioning of the further opto-electronic element enables the lighting conditions to be more adequately adapted to the illumination of the desired part of the light emission window of the luminaire. For example, a preferred embodiment of the luminaire in accordance with the invention is characterized in that the further opto-electronic element is essentially eccentrically arranged with respect to the optical axis.

If a plurality of opto-electronic elements per collimating element is provided, it may be desirable for the position of one of the opto-electronic elements to coincide with the optical axis of the associated collimating element. For this purpose, in an alternative preferred embodiment of the luminaire in accordance with the invention, the further opto-electronic element is essentially arranged on the optical axis.

Preferably, the optical axes of the collimating elements are arranged so as to be substantially parallel to each other. The manufacture of a luminaire is simplified considerably by integrating the collimating elements in a so-called optical surface. Since the collimating elements are arranged in a side-by-side relationship in one optical plane, these collimating elements do not all illuminate the same part of the light emission window. By providing, for each collimating element and given the position of the collimating element with respect to the other collimating elements, the opto-electronic elements in the desired (eccentric) positions, the direction of the light beams passing through the plurality of collimating elements is adapted to the desired illumination of the light emission window.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

In the drawings:

Fig. 1 A is an example of a front view of a signaling lamp provided with a luminaire in accordance with the invention;

Fig. IB shows an alternative example of a front view of a signaling lamp provided with a luminaire in accordance with the invention; Fig. 2 is a sectional view of a luminaire in accordance with the invention in the y-z plane;

Fig. 3 is a sectional view of the luminaire shown in Fig. 2 in the x-z plane; Fig. 4 is a sectional view of the luminaire shown in Fig. 2 in the x-y plane, and Figs. 5A-D show light contour lines in the x-z plane caused by one or more opto-electronic elements in different positions with respect to the optical axis of the collimating element with which the opto-electronic element or opto-electronic elements is (are) associated.

The Figures are purely diagrammatic and not drawn to scale. Particularly for clarity, some dimensions are exaggerated strongly. In the Figures, like reference numerals refer to like parts whenever possible.

Fig. 1A and IB very diagrammatically show examples of front views of two different signaling lamps 1; 1', which are both provided with at least a luminaire in accordance with the invention. For clarity, and for correspondence between the Figures, an x-y-z coordinate system is shown. The other Figures all show cross-sectional views of the luminaire in accordance with the indicated planes.

The signaling lamp 1 shown in Fig. 1 A is a traffic light, wherein the light emission window 3 is partly covered by a mask 12, so that an arrow 11 lights up when the light source is switched on. In the case of the signaling lamp 1' shown in Fig. IB, the light emission window 3 is partly covered by another mask 12', the picture representing a stationary or (seemingly) moving pedestrian, said picture lighting up when the light source is switched on.

Fig. 2 is a diagrammatic sectional view of a luminaire in accordance with the invention in the y-z plane. The radiation beams shown are diagrammatic. The luminaire comprises a housing 2 which is provided with a light emission window 3. Said housing 2 accommodates a plurality of opto-electronic elements 5, 5', ...; 6, 6', ...; 7, 7', ... and a plurality of collimating elements 15; 16; 17. In the example shown in Fig. 3, the opto-electronic elements 5, 5', ...; 6, 6', ...; 7, 7, ... are light-emitting diodes (LEDs) and the collimating elements 15; 16; 17 are so-called positive Fresnel lenses. In operation, the optoelectronic elements 5, 5', ...; 6, 6', ...; 7, 7', ... emit visible light. Each one of the collimating elements 15; 16; 17 has an optical axis 25; 26; 27, and each one of the collimating elements 15; 16; 17 is associated with at least one opto-electronic element 5; 6; 7. In accordance with the invention, the opto-electronic element 5; 6; 7 is arranged essentially off the optical axis 25; 26; 27 of the collimating elements 15; 16; 17 with which the opto-electronic element 5; 6; 7 is associated. In Fig. 2, each one of the collimating elements 15; 16; 17 is associated with at least one further opto-electronic element 5'; 6'; 7, which is also essentially eccentrically arranged with respect to the optical axis 25; 26; 27. There is a possibility that the position of the further opto-electronic element coincides with the optical axis of the collimating element (not shown in Fig. 2).

In the example shown in Fig. 2, the optical axes 25; 26; 27 of the collimating elements 15; 16; 17 are directed so as to be substantially parallel to each other. Fig. 3 is a very diagrammatic, sectional view of the luminaire shown in Fig. 2 in the x-z plane. The optical axes of the collimating elements 15; 16; 17; 18; 19 extend at right angles to the x-z plane at the location of the imaginary intersections of the dashed lines provided in each collimating element 15; 16; 17; 18; 19. To simplify the assembly of the unit, the collimating elements 15; 16; 17; 18; 19 have a hexagonal structure in the x-z plane (i.e. the plane transverse to the optical axes 25; 26; 27; 28; 29). In Fig. 3, each one of the collimating elements 15; 16; 17; 18; 19 is associated with eight opto-electronic elements 5, 5', ...; 6, 6', ...; 7, 7, ...; 8, 8', ...; 9, 9', ..., which are all arranged essentially off the optical axis of the associated collimating element 15; 16; 17; 18; 19. There is a possibility that the position of one of the further opto-electronic elements 5'; 6'; 7'; 8'; 9' coincides with the optical axis of the collimating element (not shown in Fig. 3).

By asymmetrically positioning the opto-electronic elements 5, 5', ...; 6, 6', ...; 7, 7, ...; 8, 8', ...; 9, 9', ... with respect to the optical center of the associated collimating elements 15; 16; 17; 18; 19, a non-homogeneous light distribution on the light-emission window 3 is obtained. A suitable choice of the "off-axis" positioning of the opto-electronic elements 5, 5', ...; 6, 6', ...; 7, 7, ...; 8, 8', ...; 9, 9', ... a light distribution is obtained which is adapted to the shape of the mask 12; 12', so that the majority of the light leaving the luminaire via the light emission window 3 is passed directly by the part of the light emission window which is not covered by the mask 12; 12'. "Off-axis" positioning is to be taken to mean here the degree of eccentricity of the opto-electronic element with respect to the optical axis of the associated collimating element.

Parts of the light emission window 3 which allow light to pass, i.e. the light is not blocked by the mask 12; 12', can be efficiently illuminated by providing opto-electronic elements 5, 5', ...; 6, 6', ...; 7, 7, ...; 8, 8', ...; 9, 9', ... and collimating elements 15; 16; 17; 18; 19 only behind the parts of the light emission window 3 to be illuminated. Fig. 4 is a diagrammatic, sectional view of the luminaire shown in Fig. 2 in x-y plane. To simplify the drawing, the plurality of collimating elements 17; 18; 19 is shown as one optical structure 20. The radiation beams shown are diagrammatic.

The optical structure 20 comprises, for example, 7, 19 or 38 hexagonal Fresnel lenses (positive lenses). A particularly attractive embodiment of the luminaire in accordance with the invention comprises 19 Fresnel lenses arranged in a hexagonal structure (see Fig. 3), 8-10 LEDs being used for each Fresnel lens, which LEDs are provided on a customary PCB (printed circuit board) structure.

In Fig. 5A-D, various light contour lines in the x-z plane are shown, which are caused by one or more opto-electronic elements in different positions with respect to the optical axis of the collimating element with which the opto-electronic element or optoelectronic elements is (are) associated. Lines of at least substantially equal illuminance correspond to the light contour lines. In each one of the Figures 5A-D, the optical axis of the collimating element extends perpendicularly to the x-z plane at the location of the intersection of the x-axis and the z-axis.

In Fig. 5 A, one light-emitting diode (LED) 105, as used in the known luminaire, is shown, said LED being positioned on the optical axis of the Fresnel lens with which the LED is associated. The light contours comprise concentric circles with the optical axis of the Fresnel lens as the imaginary center. If the LED is arranged in the focus of the Fresnel lens, the Fresnel lens emits a substantially parallel light beam. If the LED is arranged at a distance which is substantially larger or smaller than the focal distance of the Fresnel lens, said Fresnel lens emits a converging or diverging light beam.

Fig. 5B shows one LED 106 in accordance with the invention which is eccentrically positioned with respect to the optical axis of the Fresnel lens with which the LED is associated. The light contours comprise concentric circles with the LED as the imaginary center. If the LED is arranged at a distance from the Fresnel lens equal to the focal distance of the Fresnel lens, said Fresnel lens emits a substantially parallel light beam at a certain angle. If the LED is arranged at a distance which is substantially larger or smaller than the focal distance of the Fresnel lens, said Fresnel lens emits a converging or diverging light beam at a specific angle. Such light beams are alternatively referred to as pre-directed light beams. The off-axis position of the LED determines the direction of the light beam.

Fig. 5C shows the light contour lines as caused by two LEDs 107, 107', which, in accordance with the invention, are eccentrically positioned with respect to the optical axis of the Fresnel lens with which the LEDs are associated. The light contours comprise symmetric contour lines. The arrangement of the LEDs with respect to each other and the distance between the LEDs determine the shape of the beam.

Fig. 5D shows the light contour lines as caused by three LEDs 108, 108', 108" which, in accordance with the invention, are eccentrically positioned with respect to the optical axis of the Fresnel lens with which the LEDs are associated. In the example shown in Fig. 5D, one of the LEDs is placed on the optical axis of the Fresnel lens. The light contours comprise symmetric contour lines. The arrangement of the LEDs with respect to each other and the distance between the LEDs determine the shape of the beam.

It will be obvious that within the scope of the invention many variations are possible to those skilled in the art. For example, the optical axes of the collimating elements do not necessarily have to extend parallel to each other.

The scope of protection of the invention is not limited to the examples given herein. The invention is embodied in each novel characteristic and each combination of characteristics. Reference numerals in the claims do not limit the scope of protection thereof. The use of the term "comprising" does not exclude the presence of elements other than those mentioned in the claims.

Claims

CLAIMS:

1. A luminaire comprising a housing (2) having a light emission window (3), wherein the housing (2) accommodates a plurality of opto-electronic elements

(5, 5', ...; 6, 6', ...; 7, 7, ...; 8, 8', ...; 9, 9', ...) and a plurality of collimating elements (15; 16; 17; 18; 19), wherein, in operation, the opto-electronic elements (5, 5', ...; 6, 6', ...; 7, 7, ...; 8,

8', ...; 9, 9', ...) emit visible light, and wherein each of the collimating elements (15; 16; 17; 18; 19) has an optical axis (25; 26; 27; 28; 29) and is associated with an opto-electronic element (5; 6; 7; 8; 9), characterized in that the opto-electronic element (5; 6; 7; 8; 9) is arranged essentantially eccentrically with respect to the optical axis (25; 26; 27; 28; 29) of the collimating element (15; 16; 17; 18; 19) with which the opto-electronic element (5; 6; 7; 8; 9) is associated.

2. A luminaire as claimed in Claim 1, characterized in that with at least one collimating element (15; 16; 17; 18; 19) at least one further opto-electronic element (5'; 6'; 7'; 8'; 9') is associated.

3. A luminaire as claimed in Claim 2, characterized in that the further optoelectronic element (5'; 6'; 7'; 8'; 9') is essentially eccentrically arranged with respect to the optical axis (25; 26; 27; 28; 29).

4. A luminaire as claimed in Claim 2, characterized in that the further optoelectronic element (5'; 6'; 7; 8'; 9') is essentially arranged on the optical axis (25; 26; 27; 28; 29).

5. A luminaire as claimed in Claim 1 or 2, characterized in that the optical axes

(25; 26; 27; 28; 29) of the collimating elements (15; 16; 17; 18; 19) are arranged so as to be substantially parallel to each other.

6. A luminaire as claimed in Claim 1 or 2, characterized in that the collimating elements (15; 16; 17; 18; 19) comprise Fresnel lenses.

7. A luminaire as claimed in Claim 1 or 2, characterized in that the collimating elements (15; 16; 17; 18; 19) in a plane transverse to the optical axis (25; 26; 27; 28; 29) have a hexagonal structure.

8. A luminaire as claimed in Claim 1 or 2, characterized in that the opto-electronic elements (5, 5', ...; 6, 6', ...; 7, 7, ...; 8, 8', ...; 9, 9', ...) comprise light-emitting diodes.

9. A signaling lamp (1 ; 1') provided with a luminaire as claimed in Claim 1 or 2.