FIELD OF THE INVENTION

The invention relates to a lighting module for use in a luminaire and a luminaire comprising such a lighting module. BACKGROUND OF THE INVENTION

Gas-discharge lamps, especially High Pressure Sodium (HPS) arc lamps, are widely used for road and residential lighting, decorative floodlighting, commercial and industrial applications, and recreational sports facilities that are both indoor and outdoor. Such lamps comprise a bright arc which emits light in an omnidirectional way and is placed in the optical center of a reflector of a luminaire, which collects and redirects the light to, for example, a road. The high brightness property and the high lumen output of such lamps make them well suited for illuminating big outdoor areas, such as roadways, parking lots, and pavements.

Nevertheless, one of the major issues with gas-discharge lamps is their high power consumption, which along with a limited lifetime make them costly in terms of use of electricity and continuous replacement. Furthermore, such lamps may suffer from poor color rendering as their emission spectrum is often limited by the emission spectrum of the gas inside the lamp. Thus, there has been a great motivation to replace such lamps with more energy-efficient alternatives, without reducing the light intensity output.

To this end, various LED (Light Emitting Diode) configurations have been proposed to replace these high brightness - high lumen output lamps. LED lamps have a much more efficient lumen to power ratio than gas-discharge lamps, and have also a longer lifetime before the lamp needs replacing. However, because gas-discharge lamps are widely used in urban infrastructures, such as street lights, which would be costly to replace, the LED replacement should be capable of operating in the already existing luminaires. Therefore, the proposed LED replacements should be compatible with the existing luminaires, i.e. be compatible with the existing socket and mimic the omnidirectional light emission of the gas- discharge lamps such that the light emitted from a replacement LED lamp is reflected properly when the LED lamp is positioned in the optical center of the reflector of the luminaire.

In the prior art, LED lamps with a hexagonally shaped heat sink has been developed, where each side of the hexagonally shaped heat sink comprises an LED light source. The heat sink is made to be elongated, such that the light emitted by the LED lamp closely resembles the omnidirectional light of an arc lamp.

An example of such an LED lamp is disclosed in the document KR968270B1 which relates to an LED lamp for a street light, where LEDs have been arranged on the surfaces of an elongated hexagonal heat sink.

However, replacing the existing gas-discharge lamps with such LED lamps presents some issues. To achieve the required lumen output, the heat sink of the LED lamp needs to be of considerable dimensions, such that the heat produced by the LEDs have sufficient surface area to dissipate from. This results in a spacious heat sink which may act as an obstacle for light being reflected by the reflector towards the light window of the reflector, thereby creating a shadowing effect, which results in a loss of light and thereby reduces the efficiency of the LED lamp.

A further issue arises as the mounting sockets used for the gas-discharge lamps are not designed to take the final, mounted orientation of the lamp into consideration as gas-discharge lamps are mostly continuously rotationally symmetric about their longitudinal axis. For the LED lamps which, due to their polygonal cross-section, are only discretely rotationally symmetric about their longitudinal axis, the surfaces of the heat sink may end up with a final, mounted position, wherein the surfaces of the heat sink are orientated in a non-optimal manner in relation to the reflector and the light window of the reflector.

In view of the above, it is an object of the present invention to provide a lighting module suitable for direct replacement of conventional high brightness gas-discharge arc lamps, without modification of the associated luminaire, and which shows improved efficiency.

In EP 2636948 a lamp is disclosed having a driver circuit supplying power to LEDs, and a supplementary integrated sensor, detecting alignment and/or orientation of the lamp. The driver circuit operates the LEDs and influence a spatial light output depending on the detected alignment and/or orientation of the lamp. The driver circuit adjusts intensity of the light output and/or a maximum permissible intensity in a dimming operation. JP 2011243512 shows a lighting device with an outer appearance of a hexagon. The hexagon is provided with, for instance, six plane substrates each connected with the adjacent one. A number of LEDs 3 (light-emitting diodes) are arrayed in adjacency on each flat plate face of the six flat substrates, with a light-emitting part of each LED exposed on the surface of the flat substrate.

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome one or more of these issues and to provide a lighting module for use in a luminaire, such that the light emission and light distribution from the luminaires are more efficient.

These and other objects may be achieved by providing a lighting module for use in a luminaire, the lighting module comprising a heat sink for dissipating thermal energy, which heat sink is polygonal in cross section, forming a number of surfaces corresponding to the polygonal shape of the heat sink, each surface extending in a longitudinal direction, where the longitudinal direction extends substantially perpendicularly to a plane of the cross section, i.e. at an angle of approximately 90 degrees to the plane of the cross section. At least one row of LEDs is located on each of at least two of the surfaces, each row comprising at least two LEDs so that light may be emitted from each surface comprising a respective row of LEDs, wherein the LEDs are configured so that the lighting module, when connected to a power source, is configured to or can be set to emit less light from at least one of the surfaces than from at least one other of the surfaces.

It should be noted, that the LEDs need not be provided by standard Light- emitting diodes, but may also be provided by other types of light emitting semi-conductor diodes, such as laser diodes.

Thereby, a lighting module for replacing conventional gas-discharge lamps without modification of the associated luminaire and with improved efficiency is provided. Furthermore, the light distribution and light emission of the lighting module in the luminaire is optimized and rendered more efficient.

The problems relating to the heat sink shadowing the light reflected from the reflector are particularly troublesome for light emitted radially away from the lighting module in the direction away from a light window of the reflector, i.e. the opening from which light from the lighting module leaves the luminaire. This is because most luminaire reflectors designed for high intensity lighting are parabolic or parabola shaped in cross section so that they are adapted to reflect light emitted inwards towards the reflector from the optical center back towards the light window such that the light exits the light window substantially perpendicularly to a plane of the light exit window. The rays emitted

substantially towards the center, center line, or vertex of the luminaire will be reflected in an inefficient manner because the rays are reflected back onto the lighting module, thereby resulting in a shadowing effect. By providing less or no current to, for example, the row of LEDs on the surface pointing towards the center, center line or vertex of a reflector of a luminaire, when the lighting module is mounted in a luminaire, less light is lost by being reflected towards the lighting module, where light rays are blocked by the lighting module, while keeping substantially the same light output from the light exit window of the luminaire. Thereby energy may be saved, while keeping substantially the same light output from the light exit window of the luminaire.

The center, center line, or vertex of the reflector of the luminaire may be defined as the point, line, or area of the reflector, where light rays are reflected back substantially towards the optical center, focus, or focal point of the reflector. The lighting module therefore blocks these light rays emitted towards the center, center line, or vertex of the reflector, when installed in the optical center, resulting in a shadowing effect. The center, center line, or vertex of the reflector may be the point, line, or area where: the slope of the reflector shape substantially equals zero, a local maximum is, or the derivative in one or more points is zero.

The reflector may be substantially arc-shaped and/or have a substantially parabolic shape and/or a substantially semi-elliptical shape, specifically in a cross section, more specifically in a cross section taken along a longitudinally extending center line of the lighting module. In three dimensions, the reflector may have a paraboloid shape, specifically an elliptic paraboloid, a paraboloid of revolution, a circular paraboloid, or a hyperbolic paraboloid. The reflector may also have other shapes that have cross-sections that are parabolic, such as a half cylinder or a cone.

The luminaire may comprise one or more reflectors, such that one or more lighting modules may be fitted in the luminaire. The lighting module may be positioned substantially in an optical center, focus, or focal point of the reflector or luminaire or light fitting.

To get an optimal light distribution, the lighting module of the invention will usually, when installed in the luminaire, be orientated such that one of the surfaces of the heat sink will be substantially parallel with the light exit window and facing away from the light exit window. Light emitted from this surface will be emitted radially away towards the vertex of the reflector.

The lighting module may be set such that less light may be emitted from at least one surface than from at least one other of said surfaces when connected to a power source. The lighting module may be configured to emit less light from at least one surface than from at least one other surface before being installed in a luminaire, but may also be set to emit less light from at least one surface than from at least one other surface, when being installed in a luminaire and connected to a power source.

The at least one surface from which less light is emitted may emit less than or equal to 95 %, 90 %, 80 %, 70 %, 60 %, 50 %, 40 %, 30 %, 20 %, 10 %, 5 % down to 0 % of the light emitted from at least one other of said surfaces. The amount of light emitted from an LED, a row of LEDs or a surface of the heat sink, may be measured by measuring the light flux, the lumen output, the luminous efficacy, or the luminous efficiency of the LED. This may be done by covering or turning off the LED, the row of LEDs or the surface(s) of the heat sink that are not to be measured, such that substantially no light is emitted from them, and leaving the LED, the row(s) of LEDs or the surface(s) of the heat sink that are to be measured, uncovered.

In an embodiment, two, three, four, five, six, or all surfaces of the heat sink, unless the at least one surface from which less light may be emitted, may be configured to or may be set to emit substantially the same amount of light. The term "same amount of light" may be defined as the amount of light emitted individually by each surface, and may vary within the uncertainty range for emitted light of each LED. The uncertainty range for emitted light may vary for each LED. This may be less than +- 5 %, +- 10 %, +- 20 %, +- 30 %, or +- 40 %.

The lighting module may comprise a base, a plug part, support part or fitting part, which may fit into a socket of a luminaire or light fitting, providing power to the lighting module and supporting or fixing it in the luminaire or light fitting. The plug part may be provided with an external thread, fitting an internal thread of the luminaire socket, especially in the situation where the lighting module replaces an existing arc lamp. The plug part may alternatively be provided with pins fitting into the luminaire socket. The lighting module may further comprise a PCB (Printed Circuit Board), an LED driver, and other members that are usual in lighting modules.

In an embodiment, the heat sink is hexagonal in cross section so as to comprise six surfaces, wherein at least one row of LEDs, each row comprising at least two LEDs, are located on each of five of the surfaces, and wherein the remaining of the surfaces comprises no LEDs, so that, when connected to a power source, no light is emitted from the latter surface.

In an embodiment, the heat sink is hexagonal in cross section so as to comprise six surfaces, wherein at least one row of LEDs, each row comprising at least two LEDs, are located on each of the six surfaces, and wherein the lighting module is configured so or can be set so that, when connected to a power source, less light is emitted from one of the surfaces than from the other of the surfaces.

The heat sink may have a substantially cylindrical shape. Cylindrical may be defined as the heat sink having two parallel base sides or ends, where a cross section of the heat sink may be circular, elliptical or polygonal, such as triangular or square, the two base sides or ends being joined by a side surface extending substantially straight in the

longitudinal direction between the two base sides. The side surface may be curved or round or may comprise a plurality of surface parts, where the surface parts may each be planar, straight, curved, and/or extend in a zig-zag shape.

The heat sink may work as a heat exchanger in order to dissipate heat generated by the LEDs, whereby a temperature of the LEDs may be moderated.

One or more of the surfaces of the heat sink may be configured to emit less light than one or more other surfaces of the heat sink.

The number of LEDs per row and/or surface may be varied, and may be at least two, three, four, five, six, seven, eight, ten, fifteen, twenty, fifty, eighty, a hundred or more, whereby the light output may be varied. The number of LEDs per row and/or surface may similarly be less than three, four, five, six, seven, eight, ten, fifteen, twenty, fifty, eighty, or a hundred. Preferably, the number of LEDs per row and/or surface is two to forty, three to thirty, four to twenty, or six to ten. The term "rows of LEDs" may be defined as at least two LEDs that may be aligned along a direction parallel to a longitudinal axis of the lighting module. The rows of LEDs may also have LEDs that are not necessarily strictly aligned with each other, such that they are shifted with respect to each other, in a direction perpendicular to the longitudinal axis of the lighting module.

A reflector in a luminaire, in which the LED may be positioned, may reflect light that is emitted in other directions than directions towards a light exit window of the luminaire, such that this light may be reflected in the direction of the light exit window. The luminaire may be a luminaire for gas-discharge lamps, but may alternatively also be adapted for LEDs, such that some components of the lighting module may be omitted, for example a driver.

The term "located on the surface" as used in this specification may include, e.g., that the LED is located in or embedded in a cut-out, cavity or depression of the surface. The LEDs may be covered, for example, by a protective, substantially transparent film, while still being "located on the surface".

The light exit window may be defined as an aperture or a main aperture of the luminaire from which the light from the LED exits the luminaire. Usually, the light exit window is located substantially oppositely from a top of the reflector of the luminaire, such that the light reflected by the reflector will exit the light exit window.

In general, the lighting module is configured to or can be set to emit more light from at least one of the surfaces than from at least one other of the surfaces when connected to a power source. For example, more light may be emitted from the surfaces pointing towards the light exit window, whereby less rays may be blocked by the lighting module after being reflected by the reflector.

In an embodiment, the lighting module is configured to or can be set to vary the current provided to at least one row of LEDs on the at least one surface from which less light is emitted, when connected to a power source, independently from the current provided to at least one other of the rows of LEDs.

This may be achieved by a driver configured to vary the current provided to the at least one row of LEDs on the at least one surface from which less light is emitted.

A driver may be positioned in a base or a socket of the lighting module, whereby the lighting module may be used as a replacement lamp for an existing luminaire.

By providing less or no current to, for example, the row of LEDs on the surface pointing towards the center, center line, or vertex of a reflector of a luminaire, when the lighting module is mounted in a luminaire, less light is lost by being reflected towards the lighting module where light rays are blocked by the lighting module, while keeping substantially the same light output from the light exit window of the luminaire. The driver may also vary the current to different rows of LEDs in order to further improve the efficiency of the lighting module and/or vary the light distribution.

The light output of the luminaire may be defined as the light flux exiting the light exit window, for example in lumen. The rays emitted substantially towards the center, center line, or vertex of the luminaire will be reflected in an inefficient manner because the rays are reflected back onto the lighting module, thereby resulting in a shadowing effect.

In a development of the present embodiment, the lighting module further comprises a controller or circuitry configured to control the current provided to the at least one of the rows of LEDs on the at least one surface from which less light is emitted when connected to a power source.

In a further development, the controller is configured such as to individually control a light output of one or more of the LEDs of the at least one of the rows of LEDs when connected to a power source.

The provision of a controller or circuitry configured to control the current provided to a row of LEDs or to individual LEDs of a row of LEDs may optimize the efficiency of the lighting module in the luminaire depending on the orientation of the surfaces, while keeping substantially the same light output. The controller or circuitry may re-allocate power saved from a row of LEDs on a surface from which less light is emitted, in order to provide more power to and emit more light from another row of LEDs. This may, for example, be a row of LEDs oriented substantially towards the light exit window of the luminaire, such that the light output emitted from the light exit window may be increased.

In an embodiment, the at least one surface from which less light is emitted when connected to a power source, comprises no LEDs, or the lighting module is configured so or can be set so that when the lighting module is connected to a power source, the current provided to at least one LED or at least one row of LEDs on the at least one surface from which less light is emitted, is less than the current provided to at least one of the other rows of LEDs located on at least one other of the surfaces.

By providing less current to the row of LEDs on the surface pointing towards the center, center line, or vertex of a reflector of a luminaire or not including LEDs on that surface, when the lighting module is mounted in a luminaire, less light is lost by being reflected towards the lighting module where light rays are blocked, while keeping

substantially the same light output from the light exit window of the luminaire.

In an embodiment, the at least one surface from which less light is emitted when connected to a power source, comprises a smaller number of LEDs compared to the at least one other of the surfaces.

By providing a smaller number of LEDs to the row of LEDs on the surface pointing towards the center, center line, or vertex of a reflector of a luminaire, when the lighting module is mounted in a luminaire, less light is lost by being reflected towards the lighting module where light rays are blocked, while keeping substantially the same light output from the light exit window of the luminaire.

In an embodiment, at least one LED or at least one row of LEDs on the at least one surface from which less light is emitted is of lower nominal power compared to the at least one other of the surfaces.

The nominal power of an LED is substantially the power that the LED consumes, which is defined by the components in the LED. By providing an LED of lower nominal power or at least one row of LEDs having a lower total nominal power on the at least one surface from which less light is emitted, to for example the surface pointing towards the center, center line, or vertex of a reflector of a luminaire, when the lighting module is mounted in a luminaire, less light is lost by being reflected towards the lighting module where light rays are blocked, while keeping substantially the same light output out of the light exit window of the luminaire. This can be done by providing LEDs using less power and thereby emitting less light, or by providing more efficient LEDs that use less power but provide the same amount of light as a less efficient LED, i.e. by using LEDs with higher luminous efficacy or higher luminous efficiency.

In an embodiment, the lighting module comprises a rotation mechanism allowing the heat sink and/or rows of LEDs to be rotated with respect to a base of the lighting module.

This can be done by providing a rotation mechanism as disclosed in documents US2012080994A1 or US2015241042A1, the contents of which are hereby included herein in their entirety.

By including ring electrodes in the rotation mechanism as it is disclosed in the documents, contact between the electrodes of the socket of the luminaire and the plug of the lighting module is maintained when rotating the lighting module.

By including such a rotation mechanism, the surface from which less light is emitted when the lighting module is connected to a power source may be rotated such that said surface points towards the center, center line, or vertex of a reflector of a luminaire, when the lighting module is mounted in a luminaire, whereby less light is lost by being reflected towards the lighting module where light rays are blocked, while keeping

substantially the same light output out of the light exit window of the luminaire. The amount of light rays emitted from other surfaces that are blocked by the lighting module is therefore less, whereby substantially the same light output may be kept, even when the total amount of light emitted from the lighting module is less. In a development of the latter embodiment, the rotation mechanism is configured so that the heat sink and/or rows of LEDs due to pull of gravity rotates into a set position when the lighting module is installed in a luminaire or light fitting.

Said set position may be so that a or the surface from which light is emitted when the lighting module is connected to a power source points upwards, i.e. in a direction substantially opposite a direction of earth gravity. The rotation mechanism may comprise a counterweight so that the heat sink and/or rows of LEDs rotates into the set position when the lighting module is installed in a luminaire or light fitting. The counterweight may be integrated or embedded in the lighting module, specifically in, within and/or forming part of the heat sink. The counterweight may be positioned eccentrically from a center line of the heat sink or lighting module, the center line extending in the longitudinal direction.

In an alternative or supplementary embodiment, the rotation mechanism comprises a manual adjustment mechanism, such that the heat sink may be rotated into a set position by a user. This may allow the person installing the lighting module of the invention in a luminaire to orient the surface from which less light is emitted correctly with respect to the reflector, regardless of the position of the base of the lighting module with respect to the socket of the luminaire.

In an alternative or supplementary embodiment, the rotation mechanism comprises an automatic adjustment mechanism, such that the heat sink and/or rows of LEDs may be rotated into a set position.

In an alternative or supplementary embodiment, the rotation mechanism may comprise a fixation mechanism or locking mechanism, such that the orientation of the lighting module may be fixed. The fixation mechanism or locking mechanism, may be a snap-lock, a clamp, a ring lock, or any other type of fixation or locking mechanisms.

In an embodiment, the lighting module comprises a sensor configured to sense a position of a reflector and/or light exit window of a luminaire in which the lighting module can be installed, the sensor being connected to a controller configured to control a light output of one or more of the LEDs or rows of LEDs with respect to the position of the reflector and/or exit window when connected to a power source.

The sensor may be a photo sensor or a photodetector adapted to detect light or other electromagnetic energy. The sensor converts light photons into current. The sensor may be of the type using detection mechanisms such as: photoemission, photoelectric, photovoltaic, thermal, polarization, photochemical, or weak interaction effects. In an alternative or supplementary embodiment, the previously described rotation mechanism is included, the controller being configured to rotate the heat sink and/or rows of LEDs into said set position when the lighting module is installed in a luminaire or light fitting. The sensor may be connected and/or communicate with the rotation mechanism, the driver, an/or the controller, such that the controller can be configured to rotate the heat sink and/or rows of LEDs and/or vary the light output of one or more of the LEDs or rows of LEDs, based on measurements from the sensor.

In a development of the present embodiment, the sensor comprises an LED as a light detection device.

This can be achieved by said LED being reversed biased, such that it acts as a photodiode for detecting light.

By providing such a sensor, said surface from which less light is emitted when the lighting module is connected to a power source may be oriented such that it points towards the center, center line, or vertex of a reflector of a luminaire, when the lighting module is mounted in a luminaire, whereby less light is lost by being reflected towards the lighting module where light rays are blocked, while keeping substantially the same light output out of the light exit window of the luminaire.

In an embodiment, the lighting module comprises a heat pipe to improve dissipation of thermal energy and/or to improve thermal management.

More specifically, the heat pipe may improve dissipation of heat energy from one or more LEDs of the lighting module. This may be achieved by including a heat pipe working as a heat transfer device and potentially combining the principles of thermal conductivity and phase transition to improve heat dissipation of thermal energy and thermal management. The heat pipe may be a constant conductance heat pipe, a vapor chamber, a variable conductance heat pipe, a pressure controlled heat pipe, a diode heat pipe, a thermosiphon, rotating heat pipe, or any other heat pipe type.

Another aspect of the present invention provides a luminaire or light fitting comprising an lighting module according to any one of the above embodiments and a reflector surface for reflecting light emitted from the lighting module, wherein the lighting module is fitted in the luminaire or light fitting such that the surface which emits less light faces a center, center line or vertex of the reflector surface; or faces in a direction opposite to a main illumination direction or a light exit window; or faces in a direction opposite to a direction of earth gravity. As previously explained, by orienting the surface which emits less light when the lighting module is connected to a power source in this manner, when the lighting module according to the invention is mounted in a luminaire, less light is lost by being reflected towards the lighting module where light rays are blocked, while keeping substantially the same light output out of the light exit window of the luminaire.

The reflector may be substantially arc-shaped and/or have a substantially parabolic shape and/or a substantially semi-elliptical shape, specifically in a cross section, more specifically in a cross section taken along a longitudinally extending center line of the lighting module. The luminaire may comprise one or more reflectors, such that one or more lighting modules may be fitted in the luminaire. The lighting module may be positioned substantially in an optical center of the reflector or luminaire or light fitting.

It is noted that the invention relates to all possible combinations of features recited in the claims. BRIEF DESCRIPTION OF THE DRAWINGS

These 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.

Fig. 1 shows a cross sectional view of a lighting module according to an embodiment of the invention, where the lighting module is placed in a luminaire with a parabolic shaped reflector in cross-section, and where no light is emitted from one surface of the lighting module.

Fig. 2 shows a cross sectional view similar to that of Fig. 1 of a lighting module according to an embodiment of the invention, where the lighting module is placed in a luminaire with a parabolic shaped reflector in cross-section, and where less light is emitted from a surface of the lighting module than from other surfaces of the lighting module.

Fig. 3 shows a side-view of a lighting module according to an embodiment of the invention, comprising a plurality of rows of LEDs and a driver, and where a longitudinal axis of the lighting module is shown.

Fig. 4 shows a side-view similar to that of Fig. 3 of a lighting module according to an embodiment of the invention, comprising a plurality of rows of LEDs and a rotation mechanism, and where a longitudinal axis of the lighting module is shown.

Fig. 5 shows a cross sectional view of the lighting module shown in Fig. 1 which has been modified, to comprise a counterweight. Fig. 6 shows a side-view similar to that of Fig. 3 of a lighting module according to an embodiment of the invention, comprising a plurality of rows of LEDs, a controller, and where the longitudinal axis is shown.

Fig. 7 shows a side-view similar to that of Fig. 3 of a lighting module according to an embodiment of the invention, comprising a plurality of rows of LEDs, a sensor, and where the longitudinal axis is shown.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and to fully convey the scope of the invention to the skilled person.

Fig. 1 shows a cross sectional view of a lighting module 1 according to an embodiment of the invention, where the lighting module 1 is placed in a luminaire (not shown) with a parabolic shaped reflector 2 in cross-section. The lighting module 1 comprises a heat sink 10 for dissipating thermal energy. The heat sink 10 is hexagonal in cross section so as to form six surfaces 11, 12 corresponding to the polygonal shape of the heat sink 10, each surface 11, 12 extending in a longitudinal direction LA (shown on Fig. 3), where the longitudinal direction LA extends perpendicularly to the plane of the cross section. The lighting module 1 comprises at least one row of LEDs 8 (only one of which LEDs is visible in cross-section on Fig. 1), each row 8 comprising at least two LEDs 13, located on each of five of the six surfaces 11, and wherein the remaining surface 12 comprises no LEDs, so that, when connected to a power source, no light is emitted from the latter surface 12. As illustrated by the arrows on the figure, five surfaces 11 emit the same amount of light, whereas the remaining surface 12 emits no light.

As mentioned in the background section, a problem related to LED lamps of the prior art is that light hitting the surface of the reflector in an orthogonal or substantially orthogonal angle, will be reflected back towards the lighting module, resulting in light being blocked before reaching the light exit window. By omitting light emission from the surface 12 pointing towards the center, center line or vertex 23, 25 of the reflector 2 of the luminaire, when the lighting module 1 is mounted in the luminaire, the overall efficiency of the lighting module may be improved, as the lighting module does not consume energy to emit light that would have otherwise been blocked by the lighting module 1. The energy consumption of the lighting module may therefore be reduced, while keeping substantially the same light output from the light exit window 22 of the luminaire.

As shown in Fig. 1, the reflector 2 has a parabolic shape in a cross section taken along a longitudinally extending center line of the lighting module 1. In three dimensions, the reflector 2 has a paraboloid shape. To get an optimal light distribution, the lighting module 1 is installed in the luminaire, to be orientated such that one of the surfaces 12 of the heat sink 10 is parallel with the light exit window 22 and faces away from the light exit window 22. Thereby, no light is emitted from this surface 12 towards the vertex 23 of the reflector 2.

The lighting module 1 further comprises a base 17 (shown e.g. in Fig. 3) adapted to connect the lighting module 1 to a socket of the luminaire. As the lighting module 1 may be designed to replace conventional lamps, the socket of the luminaire and the base 17 will often be of the screw, bayonet, or pin type. The lighting module 1 further comprises a secondary heat sink 24 (shown e.g. in Fig. 3) arranged at each longitudinal end of the heat sink 10. The secondary heat sinks 24 have a truncated cone shape which improves heat dissipation by providing a large surface area in contact with the ambient air.

Fig. 2 shows a cross sectional view similar to that of Fig. 1 wherein a lighting module 1 according to another embodiment of the invention is shown arranged in the reflector 2. The shown lighting module differs from the one shown in Fig. 1, in that it comprises a row of LEDs 8 on each of the six surfaces 11, 12. The lighting module 1 is configured such that less light is emitted from one surface 12 of the lighting module 1 than from the other surfaces 11 of the lighting module 1, as indicated by the arrows on the figure. This may be achieved by providing the surface 12 from which less light is emitted with fewer LEDs 13 than the other surfaces, or by configuring the lighting module 1 such that less current is provided to the surface 12 from which less light is emitted, during operation of the lighting module 1. By doing this, a lighting module 1, wherein one of the surfaces 12 is statically configured to emit less light than the other surfaces 11 , is achieved.

Alternatively, the lighting module 1 may be configured to selectively decrease the current provided to one of the surfaces during operation, whereby the surface from which less light is emitted may be selected dynamically. The advantage of providing a lighting module 1 capable of dynamically selecting which surface less light is emitted from, is that the final orientation of the surfaces 11, 12 relative to the reflector, when the lighting module 1 is mounted in the luminaire, is trivial. It may therefore be ensured that the surface 12 from which less light is emitted may be oriented towards the vertex 23 of the reflector 2.

Fig. 3 shows a side-view of a lighting module 1, according to an embodiment of the invention. Like the lighting modules of Fig. 1 and 2, the shown embodiment comprises a row of LEDs 8 on each of the surfaces 11, 12 or five of the six surfaces 11. The shown lighting module 1 further comprises a driver 9. The driver 9 is configured to convert and/or regulate the voltage supplied by a power source of the luminaire, such that the lighting module 1 may be retrofitted in a luminaire intended for a conventional lamp. Each of the rows of LEDs 8 comprises eight LEDs 13. The driver 9 is positioned in the base 17 of the lighting module 1.

Fig. 4 shows a side-view of a lighting module 1 according to an embodiment of the invention. The shown lighting module 1 comprises a rotation mechanism 15 which allows the heat sink 10 to be rotated with respect to a base 17 of the lighting module 1. In Fig. 4 the rotation mechanism 15 is positioned between the base 17 and one of the secondary heat sinks 24. The rotation mechanism 15 may alternatively be positioned between the heat sink 10 and the base 17 if no secondary heat sinks 24 are present or alternatively in the base 17.

The rotation mechanism 15 may be driven manually by hand, whereby the person installing the lighting module 1 into the luminaire may rotate the heat sink 10 after connecting the base 17 to the socket to orient the first surface 12 towards a set point on the surface 21 of the reflector 2.

Alternatively, the rotation mechanism 15 is configured so that the heat sink 10, due to pull of gravity rotates into a set position when the lighting module 1 is installed in a luminaire or light fitting. In Fig. 5, the rotation mechanism 15 comprises a counterweight 18 integrated or embedded in the lighting module 1, specifically in, within and/or forming part of the heat sink 10, such that the lighting module 1 is provided with an un-even weight distribution. When installed, the counter weight 18 will fall towards the lowest point in the gravitational field, i.e. the rotation mechanism 15 will rotate to minimize the potential energy of the mass of the lighting module 1. The surface 12 from which less light is emitted may be opposite the counter weight 18, such that the surface 12 from which less light is emitted is oriented upwards with respect to the gravitational field when the rotation mechanism 15 rotates into its equilibrium, and thus also oriented towards the vertex 23 of the reflector 2.

In other embodiments, the rotation mechanism 15 may include an automatic adjustment mechanism adapted for automatically orienting the surface 12 from which less light is emitted in a predetermined direction in relation to the luminaire when the lighting module 1 is installed in the luminaire. Such an automatic adjustment mechanism may be driven electronically by a motor, whereby the orientation of the surface 12 from which less light is emitted and the other surfaces 11 may by adjusted continuously. This may be autonomously controlled by a controller 14 of the lighting module 1 or it may be controlled remotely through a wireless control unit.

Fig. 6 shows a lighting module 1 according to an embodiment of the invention. The shown embodiment comprises a controller 14 configured to control the current provided to the at least one of the rows of LEDs 8 on the at least one surface 12 from which less light is emitted when connected to a power source. The controller 14 is positioned between the base 17 and one of the secondary heat sinks 24, but may alternatively be positioned between the heat sink 10 and the base 17 if no secondary heat sinks 24 are present, or may

alternatively be positioned in the base 17.

In a further development, the controller 14 is configured such as to individually control a light output of one or more of the LEDs 13 of the at least one of the rows of LEDs 8 when connected to a power source.

In a further development shown in Fig. 7, the lighting module 1 comprises a sensor 16 configured to sense a position of the lighting module 1 with respect to the reflector 2 and/or the light exit window 22 of a luminaire, when the lighting module 1 is installed. The sensor 16 is connected to a controller (not shown in Fig. 7) configured to control a light output of one or more of the LEDs 13 or rows of LEDs 8. The surface 12 from which less light is emitted may thereby be selectively chosen based on the measurement of the sensor 16. The sensor 16 is here positioned between the base 17 and one of the secondary heat sinks 24. The sensor 16 may alternatively be positioned between the heat sink 10 and the base 17 if no secondary heat sinks 24 are present, or alternatively in the base 17.

Such sensors 16 may also advantageously be provided in embodiments comprising an automatically adjusting rotation mechanism 15. The rotation mechanism 15 may then position the lighting module 1 based on the position determined by the sensor(s) 16.

It is noted that the invention relates to all possible combinations of features recited in the claims, and that features such as the driver, controller, the rotation mechanism, the sensor, and the heat pipe may be incorporated into any embodiment.