Abstract
A lighting device (100), comprising a plurality of light sources (110), a cover (120) comprising an at least partially light-transmissive material, wherein the cover at least partially encloses the plurality of light sources, and a plurality of reflectors (130) arranged within the cover and at respective peripheral portions of the cover, wherein a first set of light sources (140) is arranged within the plurality of reflectors such that the light sources within each reflector is configured to emit a respective bundle of light from the lighting device, and wherein a second set of light sources (150) is arranged outside the plurality of reflectors and configured to emit light from the lighting device, wherein the lighting device further comprises a control unit (160) configured to individually control the operation of the first and second sets of light sources.
Claims
1. A lighting device comprising a plurality of light sources, a cover comprising an at least partially light-transmissive material and elongating along an axis, A, wherein the cover at least partially encloses the plurality of light sources and defines a mixing chamber for at least a portion of the light emitted from the plurality of light sources during operation, and a plurality of reflectors arranged within the cover and at respective peripheral portions of the cover, wherein a first set of light sources of the plurality of light sources is arranged within the plurality of reflectors such that the light sources within each reflector is configured to emit a respective bundle of light from the lighting device, and wherein a second set of light sources of the plurality of light sources is arranged outside the plurality of reflectors and configured to emit light from the lighting device, wherein the lighting device further comprises a control unit configured to individually control the operation of the first and second sets of light sources, and wherein at least two reflectors of the plurality of reflectors are arranged in a plane, B, perpendicular to the axis, A, or wherein at least one reflector of the plurality of reflectors is arranged along the axis, A, and at an end portion of the cover, and wherein the cover is bulb-shaped or elongating along a principal axis, A.
2. (canceled)
3. The lighting device according to claim 1, wherein the control unit is configured to vary the luminous flux of the light emitted from at least one of the first and second set of light sources.
4. The lighting device according to claim 1, wherein the control unit is configured to maintain the total luminous flux of the light emitted from the first and second set of light sources constant as a function of time.
5. The lighting device according to claim 1, wherein the cover comprises a plurality of first portions respectively arranged in front of each reflector of the plurality of reflectors, and a second portion of the cover separate from the first portions, wherein at least one property of the plurality of first portions comprises is different from at least one property of the second portion.
6. The lighting device according to claim 5, fulfilling at least one of a surface area of the plurality of first portions being at least two times smaller than a surface area of the second portion, the plurality of first portions having a lower reflectance than the second portion, and a maximum intensity at the first portions being at least twice as high as a maximum intensity at the second portion of the light emitted from the plurality of light sources during operation.
7. The lighting device according to claim 1, wherein the plurality of reflectors and the first set of light sources are arranged within the lighting device such that the bundles of light emitted from the lighting device during operation have an overlap which is less than 30%, more preferably less than 25%, and even more preferred less than 20%.
8. The lighting device according to claim 1, wherein the reflectors of the plurality of reflectors are arranged equidistantly along the periphery of the cover.
9. The lighting device according to claim 1, wherein the number of reflectors is in the range of 2-5, more preferably 3 or 4, and even more preferred 3.
10. The lighting device according to claim 1, wherein the cover comprises a plurality of apertures, and wherein each aperture is arranged to let through a respective bundle of light from the lighting device.
11. The lighting device according to claim 10, wherein the plurality of apertures is arranged equidistantly in a circumferential direction of the cover, and wherein the length between pair of apertures is at least 5 mm, more preferably at least 8 mm, and even more preferred at least 10 mm.
12. The lighting device according to claim 1, wherein the reflectors of the plurality of reflectors are arranged along the periphery of the cover and are separated by an angle of at least 20°, preferably at least 25°, and even more preferred at least 30°, with respect to a center point of the cover.
13. The lighting device according to claim 1, wherein the at least one reflector has a reflectance of >80%, more preferably >85%, and even more preferred 90%.
14. A lighting arrangement elongating along a principal axis, A, the lighting arrangement comprising a lighting device according to claim 1, wherein the lighting device is arranged at a first end portion of the lighting arrangement, and an electrical connection connected to the lighting device for a supply of current to the plurality of light sources, wherein the electrical connection is arranged at a second end portion, opposite the first end portion, of the lighting arrangement.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the invention.
[0039] FIGS. 1a and 1b schematically show cross-sections of a lighting device according to an exemplifying embodiment of the present invention,
[0040] FIG. 2 shows a schematic diagram of the shadow quality and glare reduction as a function of the intensity of the light emitted from the first and second sets of light sources.
[0041] FIGS. 3a and 3b schematically show cross-sections of a lighting device according to an exemplifying embodiment of the present invention,
[0042] FIGS. 4a, 4b and 4c schematically shows light distribution patterns from the lighting device according to an exemplifying embodiment of the present invention, and
[0043] FIGS. 5a and 5b show lighting arrangements according to exemplifying embodiments of the present invention.
DETAILED DESCRIPTION
[0044] FIG. 1a schematically shows a cross-section of a lighting device 100 according to an exemplifying embodiment of the present invention. More specifically, FIG. 1 shows a cross-section of a cover 120 of the lighting device 100, wherein the cover 120 at least partially encloses a plurality of light sources 110. It will be appreciated that the cross-section of the cover 120 may not necessarily be circular, but may take on substantially any shape. The cover 120 comprises an at least partially light-transmissive material. The cover 120 may be a diffuser, i.e. the cover 120 may be configured to diffuse and/or scatter the light emitted from the plurality of light sources 110 during operation of the lighting device 100. The plurality of light sources 110 are divided into a first set of light sources 140 and a second set of light sources 150. It will be appreciated that the light sources (e.g. LEDs) of the first and second sets of light sources 140, 150 may be of the same kind or type. The lighting device 100 comprises a plurality of reflectors 130, schematically indicated as arches, and arranged within the cover 120. The reflectors 130 are arranged at respective peripheral portions of the cover 120. Each light source 110 of the first set of light sources 140 is arranged within a respective reflector 130. In this way, each light source 110 of the first set of light sources 140, arranged within a respective reflector 130, is configured to emit a respective bundle of light from the lighting device 100 during operation thereof.
[0045] The second set of light sources 150 of the lighting device 100 is arranged outside the plurality of reflectors 130, and the light sources 110 of the second set of light sources 150 are arranged at respective peripheral portions of the cover 120. In the exemplifying configuration of the lighting device 100 in FIG. 1a, light sources 110 of the first and second set of light sources 140, 150 are arranged in an alternating manner at the periphery of the cover 120. The lighting device 100 as exemplified comprises four light sources 110 of the first set of light sources 140 and four light sources 110 of the second set of light sources 150. The number of light sources 110 of the first set of light sources 140 (and the number of reflectors 130, respectively), may preferably be in the range of 2-5, more preferably 3 or 4, and even more preferred 3. It should be noted, however, that the number of light sources 110 of the first and second sets of light sources 140, 150 may be chosen arbitrarily. The second set of light sources 150 of the plurality of light sources 110, which is arranged outside the plurality of reflectors 130 and within the mixing chamber of the cover 120, is configured to emit light from the lighting device 100.
[0046] The lighting device 100 in FIG. 1a further comprises a control unit 160. Here, the control unit 160 is only schematically indicated, and is connected to the plurality of light sources 110 of the lighting device 100 either via wire or by wireless technology. It will be appreciated that the control unit 160 may be integrated within the lighting device 100. The control unit 160 is configured to individually control the operation of the light sources 110 of the first and second sets of light sources 140, 150. As exemplified in FIG. 1a, the control unit 160 may control the first and second sets of light sources 140, 150 such that the intensity of the light emitted from the first set of light sources 140 is the same as the intensity of the light emitted from the second set of light sources 150. Hence, the control unit 160 may hereby control the light sources 110 of the first and second sets of light sources 140, 150 such that the intensity of the light emitted from the lighting device 100 is substantially constant in an omnidirectional direction of the lighting device 100.
[0047] The first set of light sources 140 may be configured to provide light having a first color temperature, CT.sub.1, and the second set of light sources 150 may be configured to provide light having a second color temperature, CT.sub.2. The difference in color temperature between the first and second color temperatures may be 300-1200 K, more preferably 500-1100 K, and most preferred 700-1000 K. It will be appreciated that the first and second color temperatures 140, 150 may be the same. Furthermore, the first and second color temperatures 140, 150 may be in the range of 1800-5000 K, more preferably in a range of 1900-4000 K, and even more preferred in a range of 2000-3500 K. The first and second color temperatures 140, 150 may have a color rendering index of at least 80.
[0048] The reflectors 130 may have a reflectance of >80%, more preferably >85%, and even more preferred 90%. The cover 120 may have a reflectance in the range of 20-70%, more preferably 25-60%, and even more preferred 30-50%. Furthermore, the cover 120 may have an absorption which is less than 3%, such as 1% or even <1% during operation of the lighting device 100.
[0049] FIG. 1b schematically shows the same cross-section of the lighting device 100 as shown in FIG. 1a, and it is hereby referred to FIG. 1a for an increased understanding of the arrangement and functionality of the lighting device 100. In FIG. 1b, the control unit 160 controls the light sources 110 of the first and second sets of light sources 140, 150 such that the intensity of the light emitted from the first set of light sources 140 is higher than the intensity of the light emitted from the second set of light sources 150. For example, the control unit 160 may turn off the second set of light sources 150. FIG. 1b clearly discloses the emission of the respective bundles of light from each light source 110 of the first set of light sources 140, arranged within a respective reflector 130, of the lighting device 100 during operation thereof.
[0050] In FIGS. 1a and 1b, the plurality of reflectors 130 and the first set of light sources 140 are arranged within the lighting device 100 equidistantly and at the periphery of the cover 120. By this arrangement, and as indicated in FIG. 1b, the bundles of light emitted from the first set of light sources 140 of the lighting device 100 during operation have no overlap. For the possible configurations of the first and/or second sets of light sources 140, 150 in the lighting device 100, it is preferred that the overlap of the bundles of light emitted from the first and second sets of light sources 140, 150 is less than 30%, preferably less than 25%, and even more preferred less than 20%. Furthermore, the reflectors of the plurality of reflectors 130 are separated by an angle of 90° according to the embodiment of the lighting device 100 of FIGS. 1a and 1b. It will be appreciated that the plurality of reflectors 130 may be separated by an angle of at least 20°, preferably at least 25°, and even more preferred at least 30°, with respect to a center portion of the cover.
[0051] It will be appreciated that the control unit 160 of the lighting device 100 may control the light emitted from the light sources 110 of the first and second sets of light sources 140, 150 from the example of FIG. 1a to the example of FIG. 1b. In other words, the control unit 160 may be configured to keep and/or increase the intensity of the light from the light sources 110 of the first set of light sources 140, and to dim and/or to turn off the light sources 110 of the second set of light sources 150. In this change of the intensity of the light emitted from the first and second sets of light sources 140, 150 of the lighting device 100 as exemplified from FIG. 1a to FIG. 1b, the control unit 160 may still be configured to maintain the total luminous flux of the light emitted from the first and second set of light sources 140, 150 as a function of time.
[0052] In FIGS. 1a and 1b, the cover 120 of the lighting device 100 comprises a plurality of first portions 111 respectively arranged in front of each reflector of the plurality of reflectors 130. The cover 120 further comprises a second portion 112 of the cover 120 which is separate from the plurality of first portions 111 of the cover 120. The relative properties between the plurality of first portions 111 and the second portion 112 of the cover 120 may fulfill one or more of the following: for example, a surface area of the plurality of first portions 111 of the cover 120 may be at least two times smaller than a surface area of the second portion 112 of the cover 120. Furthermore, the plurality of first portions 111 of the cover 120 may have a lower reflectance than the second portion 112 of the cover 120. According to another example, a maximum intensity of the light emitted from the plurality of light sources 110 during operation at the plurality of first portions 111 may be at least two times higher than a maximum intensity at the second portion 112 of the light emitted from the plurality of light sources 110 during operation.
[0053] FIG. 2 shows a schematic diagram of the shadow quality, SQ, and glare reduction, GR, of the light emitted from the lighting device of the present invention as a function of the intensity of the light emitted from the first set of light sources, I.sub.1, and the intensity of the light emitted from the first and second sets of light sources, I.sub.1+I.sub.2, controlled by the control unit. At the left hand portion of FIG. 3, the control unit controls the light intensity of the first and second sets of light sources by operating the first set of light sources, i.e. with a relatively high (or maximum) level of I.sub.1, while setting the intensity of the light emitted from the second set of light sources, I.sub.2, at a relatively low level, a minimum level, or even at an off state. Hence, the light emitted from the lighting device during operation at the left hand portion of FIG. 2 is substantially, or completely, emitted from the first set of light sources. At this setting by the control unit, the shadow quality, SQ, of the light emitted from the lighting device, is at a relatively high level, or even at a maximum level, whereas the glare reduction, GR, is at a relatively low level, or even at a minimum level.
[0054] At the right hand portion of FIG. 2, the control unit controls the light intensity of the first and second sets of light sources by operating the first set of light sources, i.e. with a relatively high (or maximum) level of I.sub.1, while setting the intensity of the light emitted from the second set of light sources, I.sub.2, at a relatively high level, or even at maximum level. For example, the control unit may be configured to set the intensity of the light emitted from the first and second sets of light sources at the same level. At this setting by the control unit, the shadow quality, SQ, of the light emitted from the lighting device, is at a relatively low level, or even at a minimum level, whereas the glare reduction, GR, is at a relatively high level, or even at a maximum level.
[0055] FIGS. 3a and 3b schematically show cross-sections of a lighting device 100 according to an exemplifying embodiment of the present invention. In FIG. 3a, the lighting device 100 comprises a cover 120 comprising an at least partially light-transmissive material. According to this example, two light sources 110 of a first set of light sources 140 and two light sources 110 of a second set of light sources 150 are arranged within the cover 120. It will be appreciated, however, that the lighting device 100 may substantially comprise an arbitrary number of light sources 110 of the first and/or second sets of light sources 140, 150. In FIG. 3a, each light source 110 of the first set of light sources 140 is arranged within a respective reflector 130, whereas each light source 110 of the second set of light sources 150 is arranged outside the reflectors 130. The light sources 110 of the first and/or second sets of light sources 140, 150 may be LEDs. The light sources 110 are arranged on a single PCB 135, which may be flat or non-flat. In accordance with the lighting device 100 according to the previously described embodiments, the light sources 110 of the first set of light sources 140 which are arranged within the reflectors 130 are configured to emit respective bundles of light from the lighting device 100. Here, the bundles of light emitted from the first set of light sources 140 are predominantly emitted in a plane parallel to the axis, B, e.g. in a horizontal direction and/or plane according to the orientation of the lighting device 100 in the figure. Hence, the first sets of light sources 140 and the reflectors 130 are arranged such that the bundles of light are emitted from the lighting device 100 parallel to the axis, B, i.e. in a peripheral and planar direction of the cover 120 of the lighting device 100. Furthermore, the light sources 110 of the second set of light sources 150 are configured to emit light from the lighting device 100. Here, the light emitted from the second set of light sources 150 is predominantly emitted parallel to the axis, A, i.e. in a vertical direction and/or plane according to the orientation of the lighting device 100 in the figure.
[0056] FIG. 3b shows a similar lighting device 100 to that shown in FIG. 3a, and it is referred to FIG. 3a for an increased understanding. In FIG. 3b, there are provided four light sources 110 of a first set of light sources 140 and four light sources 110 of a second set of light sources 150 are arranged within the cover 120. It will be appreciated, however, that the lighting device 100 may substantially comprise an arbitrary number of light sources 110 of the first and/or second sets of light sources 140, 150. In FIG. 3b, there are provided four reflectors 130, and each light source 110 of the first set of light sources 140 is arranged within a respective reflector 130. Analogously, each light source 110 of the second set of light sources 150 is arranged outside the reflectors 130. One or more bundles of light emitted from the first set of light sources 140 during operation of the lighting device 100 may be emitted in a plane parallel to the axis, B, i.e. in a horizontal direction and/or plane. Furthermore, one or more bundles of light emitted from the first set of light sources 140 during operation of the lighting device 100 may be emitted in a direction/plane which inclined with respect to the axis, B. For example, according to FIG. 3b, this direction is obliquely upwards. Moreover, the light sources 110 of the second set of light sources 150 are configured to emit light from the lighting device 100 in an upwards direction and/or plane, parallel to the axis, A, according the exemplifying embodiment of FIG. 3b.
[0057] FIGS. 4a, 4b and 4c schematically show light distribution patterns from the lighting device according to an exemplifying embodiment of the present invention. The light distribution patterns are the results (effects) of the operation of the lighting device with one or more reflectors of the plurality of reflectors comprising an at least partially reflective (semi-reflective) layer, such as a diffuser. In FIG. 4a, the light distribution pattern is substantially circular in a peripheral and planar direction of the cover of the lighting device. In FIG. 4b, the light distribution pattern comprises four circles in the peripheral and planar direction of the cover of the lighting device. Here, there are four regions of overlap of the four bundles of light emitted from the lighting device during operation. In FIG. 4c, the light distribution pattern comprises three circles in the peripheral and planar direction of the cover of the lighting device. Here, there are three regions of overlap of the three bundles of light emitted from the lighting device during operation.
[0058] FIGS. 5a and 5b show operations of a lighting arrangement 800 according to an exemplifying embodiment of the present invention. In FIG. 5a, the lighting arrangement 800 elongates along a principal axis, A. The lighting arrangement 800 comprises a lighting device 100 according to any one of the previously described embodiments, i.e. including a cover 120, a plurality of reflectors, a first and second set of light sources (not shown), and a control unit 160 configured to individually control the operation of the first and second sets of light sources. The lighting arrangement 800 further comprises an electrical connection 830 connected to the lighting device 100 for a supply of current to the plurality of light sources of the lighting device 100.
[0059] The operation of the lighting arrangement 800 corresponds to that exemplified in FIG. 1a, namely that the intensity of the light emitted from the first set of light sources is the same as the intensity of the light emitted from the second set of light sources. Hence, the control unit 160 controls the light sources of the first and second sets of light sources such that the intensity of the light emitted from the lighting arrangement 800 is substantially constant in an omnidirectional direction of the lighting arrangement 800
[0060] The cover 120 of the lighting arrangement 800 comprises a plurality of apertures 200, which is visible by FIG. 5b. The apertures 200 are respectively arranged at the plurality of reflectors and respective light sources of the first set of light sources, such that each aperture of the plurality of apertures 200 is arranged to transmit (pass) a respective bundle of light from the lighting device 100. In FIG. 5b, the operation of the lighting arrangement 800 corresponds to that exemplified in FIG. 1b, namely that the control unit 160 controls the light sources of the first and second sets of light sources such that the intensity of the light emitted from the first set of light sources is higher than the intensity of the light emitted from the second set of light sources.
[0061] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, one or more of the cover 120, the reflector(s) 130, the first and/or second set of light sources 140, 150, etc., may have different shapes, dimensions and/or sizes than those depicted/described.
