WO2013037408A1

WO2013037408A1 - Head light apparatus with led

Info

Publication number: WO2013037408A1
Application number: PCT/EP2011/065944
Authority: WO
Inventors: Nobutaka Itagaki
Original assignee: Osram Ag
Priority date: 2011-09-14
Filing date: 2011-09-14
Publication date: 2013-03-21

Abstract

According to various embodiments, a lighting apparatus including a reflector ( 104 ) and a lighting module is provided, wherein the lighting module includes: a base plate ( 106 ); a first light generating element ( 108 ) arranged on the base plate such that light emitted by the first light generating element illuminates a first portion of a surface of the reflector; and a second light generating element ( 110 ) arranged on the base plate ( 106 ) such that light emitted by the second light generating element illuminates a second portion of the surface of the reflector, wherein a light emitting surface of the first light generating element is tilted with respect to a light emitting surface of the second light generating element.

Description

HEAD LIGHT APPARATUS WITH LED

Technical Field

[0001] Various embodiments generally relate to a lighting apparatus. Moreover, a lighting apparatus according to various embodiments is provided for producing a high beam and low beam with a replaceable LED (light-emitting diode) module which is, for example, applicable to automotive forward lighting applications. The presented replaceable LED module may be used in 2-wheel as well as 4-wheel vehicles and it may also be used in general signal light applications.

Background

[0002] The increasingly growing emission of greenhouse gases accelerates the production and sale of electrical vehicles (EVs) dramatically. One of major issues with EVs, especially in EV-motorcycles, is the limited capacity of the battery used therein. Therefore, a way of improving the cruising range of a battery driven EV might be seen in reducing power consumption for each function and component of the EV.

[0003] Currently, halogen light bulbs are used as means for lighting in motorcycles, scooters, mopeds, bikes etc. Their power consumption normally ranges from 30 W to 40 W for both the low beam and the high beam. The portion of power drawn by the head lamp equipped with a halogen light bulb within the overall system is therefore quite substantial. The other issue pertinent to the use of halogen light bulbs is their short lifetime. Thus, users have to replace the light bulb frequently which reduces usability. In addition, shortly before the end of an operating life of halogen light bulb, its power consumption increases drastically which further reduces the battery lifetime of the vehicle.

[0004] In ASEAN (Association of Southeast Asian Nations) countries where scooters, especially EV-scooters, are very prominent, the problem of the short lifetime of the halogen light bulb is reflected in a substantial portion of the scooters having their lights turned off while being driven, since the power consumed by the headlamp affects the available running time of the vehicle. In many cases, the used halogen light bulb is simply damaged. In any way, owing to the deficiencies of the used standard light bulbs, the safety of the drivers and others involved in road traffic is compromised.

[0005] The HID (high-intensity discharge) lamp is another viable light source which can be used in head lamps. It provides a high luminous efficacy and a long lifetime. However, headlamps based on HID lamps are very expensive and their presence on the lighting market for 2-wheels is very low.

[0006] In view of the issues involved in lighting applications in 2-wheel and 4-wheel vehicles mentioned above, a new light source technology and/or product is desirable which should desirably offer a low power consumption, a long lifetime, low

manufacturing costs and should be provided in the form of a replaceable light module.

[0007] Solid-state lighting (SSL), with the light-emitting diode (LED) probably being its most prominent representative, is a new technology as compared to halogen lamps and HID lamps and potentially fulfils the requirements stated above. One of the key points involved in the design of lamps using LEDs is thermal management. Multiple light sources can be employed in order to distribute the focus of heat. In such a case, however, multiple reflectors or multiple projecting lenses are required which might lead to more expensive lighting solutions. In view of this aspect, a further desirable feature may be seen in the compactness of the lamp, such that it may be attached at the front of a motorcycle, for example.

Summary

[0008] According to various embodiments, a lighting apparatus is provided which may include a reflector and a lighting module, wherein the lighting module may include: a base plate; a first light generating element arranged on the base plate such that light emitted by the first light generating element illuminates a first portion of a surface of the reflector; and a second light generating element arranged on the base plate such that light emitted by the second light generating element illuminates a second portion of the surface of the reflector, wherein a light emitting surface of the first light generating element is tilted with respect to a light emitting surface of the second light generating element.

[0009] In general, the desired low manufacturing costs and compactness of a lighting apparatus may be achieved by a single reflector design, wherein one reflector may be used for low beam and high beam. The light distribution of both lights should

additionally be in conformity with regulations for vehicle design such as ECE (Economic Commission for Europe), SAE (Society of Automotive Engineers), JIS (Japanese Industrial Standards) etc. As for now, a headlamp for a 2-wheel based on LEDs is not known to be existent on the market.

[0010] On the basis of the lighting apparatus presented in this application, several effects can be achieved. According to various embodiments of the lighting apparatus, a bi-functionality with respect to high beam and low beam based on LEDs may be achieved, wherein the lighting apparatus includes a replaceable or removable lighting module. The lighting apparatus may have a compact size, such that it can be attached or mounted at the front of a motorcycle, for example. Furthermore, the lighting apparatus may be manufactured at lower costs which makes it suitable for 2-wheel applications and it may have a low power consumption and a long lifetime. In addition, the design of the lighting apparatus may be chosen such that it meets the requirements of various road traffic regulations, such as ECE, SAE, JIS etc.

Brief Description of the Drawings

[0011] In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the invention are described with reference to the following drawings, in which:

FIG. 1 shows an embodiment of the lighting apparatus according to various embodiments;

FIG. 2A shows a further embodiment of the lighting apparatus according to various embodiments;

FIG. 2B shows the positional relation between LEDs in the exemplary lighting apparatus illustrated in FIG 2A;

FIG. 3A shows an example of a lighting module of the lighting apparatus according to various embodiments; FIG. 3B shows the positional relation between LEDs in the exemplary lighting module illustrated in FIG 3A;

FIG. 3C shows a perspective three-dimensional view of a further embodiment of the lighting module of the light apparatus according to various embodiments;

FIGS. 4A and 4B show further embodiments of the lighting apparatus according to various embodiments;

FIG. 5A shows a front view of a further embodiment of the lighting apparatus according to various embodiments;

FIG. 5B shows a cross-sectional side view of the exemplary lighting apparatus illustrated in FIG. 5A;

FIG. 6A shows a cross-sectional view of a further embodiment of the lighting module of the lighting apparatus according to various embodiments;

FIG. 6B shows a photograph of the lighting module of the lighting apparatus shown in FIG.6A according to various embodiments;

FIG. 7A illustrates an exemplary heat management system of the lighting apparatus according to various embodiments;

FIG. 7B shows an enlarged view of the thermal contact region of the lighting apparatus according to various embodiments shown in FIG. 7A;

FIG. 8A illustrates a theoretical model used for simulations of radiation patterns of the lighting apparatus according to various embodiments;

FIG. 8B illustrates the reflector model used for the simulations;

FIGS. 9A through 9F show results of the simulations with off-axis displacement of the light source; FIGS. 10A to 10J show results of simulations with on-axis displacement of the light source;

FIG. 11 shows an three-dimensional perspective view of an embodiment of the lighting module of the lighting apparatus according to various embodiments;

FIG. 12 shows exemplary embodiment of an LED driver circuit;

FIG. 13 shows an example of a typical 2- wheel;

FIG. 14 shows an exemplary lamp formed on the basis of the lighting apparatus according to various embodiments.

Description

[0012] The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the invention may be practiced.

[0013] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration". Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs.

[0014] In general, the usage of reflector based lighting solutions may offer several merits over projector based lighting solutions, i.e. lighting solutions where the light path is shaped via one or more projections lenses, such as low cost, no chromatic aberration, compact size and light overall weight and a relatively large tolerance with respect to misalignments of the components of the system. Various embodiments of the lighting apparatus may include any or an arbitrary combination of the merits just described. [0015] In accordance with one embodiment, the lighting apparatus may include a reflector and a lighting module wherein the light module may include: a base plate; a first light generating element arranged on the base plate such that light emitted by the first light generating element illuminates a first portion of a surface of the reflector; and a second light generating element arranged on the base plate such that light emitted by the second light generating element illuminates a second portion of the surface of the reflector, wherein a light emitting surface of the first light generating element is tilted with respect to a light emitting surface of the second light generating element.

[0016] According to various further embodiments of the lighting apparatus, the first portion of the surface of the reflector and the second portion of the surface of the reflector may be free of an overlap.

[0017] According to various further embodiments of the lighting apparatus an edge portion may be provided or arranged on the base plate such that it blocks a part of the light emitted by the first light generating element and/or second light generating element. The edge portion may be configured as a glare cutter, i.e. it may provides a natural cutoff of the light, thereby preventing significant amounts of light from being cast into the eyes of other road users.

[0018] In accordance with another embodiment the lighting apparatus may include a reflector and a lighting module, wherein the lighting module may include a base plate; a first light generating element arranged on the base plate such that light emitted by the first light generating element illuminates a first portion of the surface of the reflector; and a second light generating element arranged on the base plate such that light emitted by the second light element illuminates a second portion of the surface of the reflector, wherein a light emitting surface of the first light generating element may be arranged at a distance from and parallel to a light emitting surface of the first light generating element.

[0019] According to various further embodiments of the lighting apparatus an edge portion may be provided on the base plate such that it blocks a part of the light emitted by the first light generating element and/or second light generating element, the edge portion being formed as an edge of a step separating the first light generating element form the second light generating element.

[0020] According to various further embodiments of the lighting apparatus the light emitting surface of the first light generating element and/or the light emitting surface of the second light generating element may be arranged at an angle with respect to an optical axis of the reflector.

[0021] According to various further embodiments of the lighting apparatus the first light generating element and the second light generating element may be light-emitting diodes. The light emitting diodes may comprise one or more LED chips which may be packaged together or separately. The LEDs might also comprise optical elements such as microlenses arranged on their light emitting surfaces in order to shape the light emission provided by a respective LED. Furthermore, the light-emitting diodes may comprise several regions which might be controlled separately and, for example, be dimmed independently.

[0022] According to various further embodiments of the lighting apparatus the first light generating element and the second light generating elements may be arranged on respective mounting surfaces of the base plate. The light emitting surface of the first light generating element may be parallel to a first mounting surface and the light emitting surface of the second light generating element may be parallel to a second mounting surface. Therefore, the first mounting surface may be tilted with respect to the second mounting surface by the same tilt angle by which the light emitting surface of the first light generating element is tilted with respect to the light emitting surface of the second light generating element.

[0023] According to various further embodiments of the lighting apparatus the first portion of the surface of the reflector and the second portion of the surface of the reflector may overlap.

[0024] According to various further embodiments of the lighting apparatus the reflector may include a portion of a paraboloid of revolution. Alternatively, the reflector may also include a portion of a sphere. However, the reflector may include various other forms and may be formed to produce the desired light distribution patterns, for example for the low beam and the high beam when it is used as a head lamp in a vehicle.

[0025] According to various further embodiments of the lighting apparatus the lighting module may be arranged at a focal point of the reflector.

[0026] According to various further embodiments of the lighting apparatus the lighting module may further include a heat sink. The heat sink may be thermally connected to the lighting module such that heat from the lighting module may be efficiently transferred to the heat sink.

[0027] According to various further embodiments of the lighting apparatus the heat sink may include heat radiation plates which are connected to the base plate. [0028] According to various further embodiments of the lighting apparatus the heat radiation plates may be connected to the base plate through a thermally conducting sloped or tapered contact.

[0029] According to various further embodiments, the lighting apparatus may have a light generating element driver which is electrically connected to the first light generating element and/or the second light generating element and is configured to operate the first light generating element and/or second light generating element.

[0030] According to various further embodiments of the lighting apparatus the light generating element driver may be configured to allow a current to simultaneously flow through the first light generating element and the second light generating element.

[0031] According to various further embodiments of the lighting apparatus, the first light generating element and the second light generating element may be connected in series.

[0032] According to various further embodiments of the lighting apparatus, the lighting module may further include an electrical connector. The electrical connector may provide an electrical connection between the first light generating element and the second light generating element and the LED light generating element driver.

[0033] In the following, a more detailed description of various embodiments of the lighting apparatus using the accompanying figures will be given.

[0034] In FIG.l an embodiment of the lighting apparatus 100 according to various embodiments is shown. The lighting apparatus 100 includes a lighting module 102 and a reflector 104. The lighting module 102 includes a base plate 106 on which the first light generating element 108 and the second light generating element 110 may be provided. In the following, the first light generating element 108 and the second light generating element 110 will be referred to as first LED 108 and second LED 110. Materials which may be used to manufacture the base plate 106 may include materials which provide a good conduction of heat, such as aluminium alloys, carbonaceous materials, molybdenum, copper or silver as well as arbitrary combinations of those materials. The form of the base plate 106 shown in FIG.1 is only an exemplary one and is not restricted to that form. However, the base plate may have mounting surfaces, on which the LEDs may be arranged, that is the first LED 108 may be arranged on a the first mounting surface 122 of the base plate 106 and the second LED 110 may be arranged on the second mounting surface 124 of the base plate 106. The mounting surfaces may be provided with connecting pins and/or connecting pads and/or connecting sockets, for example in the form of recesses into which the LEDs may be easily inserted, through which electrical contact with the LEDs may be established. The kind of pins and/or pads and/or sockets provided on each of the mounting surfaces may be configured independently from one another to accept various kinds of commercially available LEDs which may be packaged according to SMD or TO-3 standards, for example. The LEDs may be soldered to the base plate 106 directly, or soldered to a PCB (printed circuit board) or MCPCB (metal core PCB) and then attached to the base plate 106, or inserted into respective sockets, for example, in order to be fixed to the mounting surfaces of the base plate 106. The lighting module 102 may further have a heat sink 114 or a thermally conductive element attached to it. The heat sink 114 may be provided on the back side of the base plate 106, i.e. the side of the base plate 106 which is facing away from the reflector 104. The base plate 106 may further include a connector 116, which might form a part of the housing (omitted in FIG.1) of the lighting apparatus 100 and to which connecting wiring 118 might be connected, thereby establishing electrical connection between the LEDs and an LED driver which controls the current and/or voltage provided to the LEDs.

[0035] The LEDs may be arranged on the mounting surfaces of the base plate 106 in such way that their light emitting surfaces face the reflector 104. The light emitting surface of the first LED 108 and the light emitting surface of the second LED 110 are tilted with respect to one another by a tilt angle 112. The tilt angle 112 may lie, for example, in the range between 10 and 70 degrees, or for example between 20 and 30 degrees in cases where microlenses are not provided on the light emitting surfaces of the LEDs. In the lighting apparatus 100 according to various embodiments, the tilt angle 112 may also correspond to the tilt angle between the mounting surfaces of the base plate 106 on which the LEDs are arranged. The tilt angle between the light emitting surfaces of the LEDs has the effect that light emitted by the first LED 108 covers a different area of the surface of the reflector 104 than the light emitted by the second LED 110. In the exemplary embodiment of the lighting apparatus 100 shown in FIG.1 it can be seen that the light emitted by the first LED 108 covers a broad surface of the reflector 104, whereas in comparison, the light emitted by the second LED 110 covers a rather narrow surface of the reflector 104. The form of the reflector 104, its position with respect to the lighting module 102 and the tilt angle between the light emitting surfaces of the LEDs, for example, may be configured in order to adjust the size of the emitted beam and its direction according to requirements of the environment the lighting apparatus 100 according to various embodiments might be used in. In the exemplary embodiment of the lighting apparatus 100 presented in FIG. l the beam formed by light emitted by the first LED 108 may be used as high beam and the beam formed by light emitted by the second LED 110 may be used as low beam. However, by proper design, the role of the first LED 108 and the second LED 110 may be switched.

[0036] The up-arrow 126 and a down-arrow 128 in FIG.1 indicate a possible orientation of the lighting apparatus 100 according to various embodiments as it is used as a head lamp in a 2- wheel or a 4-wheel vehicle. That is, the up-arrow 128 points away from and the down-arrow 128 points towards a surface an assumed vehicle would move on. In order to reduce the glare of the lighting apparatus 100, the base plate 106 may include an edge portion 120. In the embodiment presented in FIG. l, the edge portion 120 corresponds to a tip of the base plate 120. The edge portion 120 or glare-cutter provides a natural cutoff of the light, thereby preventing significant amounts of light from being cast into the eyes of other road users. The level of cutoff, i.e. the amount of light being cut off, may be adjusted by the positioning of the glare-cutter 120 such that it blocks more or less light reflected by the reflector 104 which might otherwise leave the lighting apparatus with a too high upwardly directed propagation component and possibly be cast into the eyes of other road users. Of course, other parameters such as the tilt angle 112, form of the reflector 104 and the positional relation between the LEDs and the reflector 104, for example, may be also configured to adjust the size and direction the beams emitted by the lighting apparatus 100 according to various embodiments. The glare-cutter 120 may be also configured to block light which, after being emitted by one or both of the LEDs, would otherwise directly leave the lighting apparatus 100, without being reflected by the reflector 104. [0037] As already mentioned, the advantage of the design inherent to the lighting apparatus 100 according to various embodiments as shown in FIG.1 is its compact design, since the specific arrangement of the LEDs on the base plate 106 allows for the use of only one reflector 106, yet still allowing the provision of a low beam and a high beam. It is to be pointed out that the various embodiments of the lighting apparatus, for example the embodiment shown in FIG.1, are not restricted to the orientation explained above and indicated by the up-arrow 126 and down-arrow 128. The embodiment of the lighting apparatus 100 may be also used upside down, i.e. rotated by 180 degrees, such that the reflector 104 is arranged above the lighting module 102. In that case, a glare- cutter functionality preventing significant amounts of light from being cast into the eyes of other road users may be implemented by provision of blocking elements directly on the base plate and/or on an outer rim of the reflector 104, for example. The glare-cutter 120 as shown in FIG.1 would not be able to provide this functionality as in the case of the upside down use as compared to the use shown in FIG.1 it would restrict beams of light leaving the reflector 104 which have a too high propagation component directed towards the road.

[0038] Another embodiment of the lighting apparatus 200 is shown in FIG.2A. The embodiment 200 shown in FIG.2A is similar to the embodiment 100 shown in FIG. l, therefore the same elements have been assigned the same reference numbers and will not be described again. Only the differences will be pointed out.

[0039] In the lighting apparatus 200 shown in FIG.2A the heat sink 114 has been omitted and the connector is formed as an inherent part of the base plate. Compared to the lighting apparatus 100 of FIG. l, the tilt angle 112 (see FIG.2B for an detailed view of

[0040] A generalized lighting module 300 is shown in FIG.3A. A three-dimensional cross-sectional view of that same lighting module 300 is shown in FIG.3C. In the exemplary lighting module 300 shown in FIG.3 or FIG. 3C, the base plate 106 is coupled to or connected with a housing 302 of the lighting apparatus according to various embodiments. The connector 116 is also attached to the housing 302. A driver (not shown in FIG.3 A) may be further included in the housing and may be configured to control the operation of the LEDs. In this exemplary lighting module 300, both LEDs are arranged being tilted with respect to the surface of the housing 302. The first angle 304 between the light generating surface of the first LED 108 with respect to a line 308 perpendicular to the surface of the housing 302 is α', the second angle 306 between the light generating surface of the second LED 110 with respect to the line 308 perpendicular to the surface of the housing 302 is β'. Typical values for the first angle 304 may be in the range between 10 and 50 degrees, for example, or between 20 and 30 degrees. Typical values for the second angle 306 may be in the range between 10 and 50 degrees, for example, or between 20 and 30 degrees. Therefore, assuming the mounting surfaces of the base plate 106 to be parallel with respect to the light generating surface of the respective LEDs, the tilt angle 112 as defined in the lighting apparatuses shown in FIG.1 and FIG.2A amounts to (180°-α'-β')= β. When the base plate 106 as depicted in FIG.3A is used, the glare- cutter may be accordingly put on or near the reflector. The first LED 108 and/or the second LED 110 might be composite LEDs, i.e. the first LED 108 and/or second LED 110 may actually comprise separate LEDs or LED-segments which may be controllable separately by the driver. Turning on or off of individual segments may be for example used to further support the glare-reduction functionality of the glare-cutter. Furthermore, further LEDs in addition to the first LED 108 and the second LED 110 may be placed on the base plate 106 in accordance with a desired light distribution pattern to be produced by the lighting apparatus in accordance with various embodiments.

[0041] In order to ensure proper and endurable operation of the LEDs, the base plate 106 may comprise a highly thermally conductive material. Heat generated by the LEDs may be primarily transferred onto the base plate 106 and may be then further transferred to the outside of the lighting apparatus via en external, an internal heat sink and/or a thermally conductive element.

[0042] In FIG.3B, a further embodiment of the lighting module 300 is shown which is similar to the lighting module 300 shown in FIG.3 A. As can be seen in FIG.3B, the first mounting surface 122 and the second mounting surface 124 do not necessarily need to share a common edge (as it is the case in the lighting module 300 shown in FIG.3 A, for example), as they may be separated by a surface 310 which may or may not carry a further light source, such as an LED. The first angle 304 between the light generating surface of the first LED 108 with respect to a line 308 perpendicular to the surface of the housing 302 is a", the second angle 306 between the light generating surface of the second LED 110 with respect to the line 308 perpendicular to the surface of the housing 302 is β". Therefore, assuming the mounting surfaces of the base plate 106 to be parallel with respect to the light generating surface of the respective LEDs, the tilt angle 112 as defined in the lighting apparatuses shown in FIG. l and FIG.2A amounts to (180°-a"- β")=β.

[0043] Further embodiments of the light apparatus 400 are shown in FIG.4A and FIG.4B, which are similar to the exemplary lighting apparatus 100 shown in FIG.1 and the exemplary lighting apparatus 200 shown in FIG.2 A, therefore the same elements have been assigned the same reference numbers and will not be described again. Only the differences will be pointed out.

[0044] In the embodiments of the lighting apparatus 400 according to various embodiments shown in FIGS.4 A and 4B, the light emitting surface of the first LED 108 is arranged at a distance from and parallel to the light emitting surface of the second LED 110. In other words, the base plate 106 may include a step or an elevated portion, on the surface of which the second LED 110 is mounted. The arranging of one of the LEDs on the step has a similar effect as the tilting of one of the light emitting surfaces against the other light emitting surface: the light emitted by each LED covers a different area on the reflector 104. In the exemplary lighting apparatus 400 shown in FIG.4A, the light generated by the first LED 108 may form the high beam whereas the light generated by the second LED 110 may form the low beam. However, by proper design, the role of the first LED 108 and the second LED 110 may be switched. The glare cutter 120 functionality may be provided by an edge portion 120 of the base plate 106. In the case of the lighting apparatus 400 shown in FIG.4 A, that edge portion 120 may be formed as an edge of the step separating the first LED 108 from the second LED 110, wherein the edge portion 120 is located between the first LED 108 and the second LED 110. The effect of the glare cutter 120, for example the amount of light that is blocked by it, may be adjusted by adjusting the height of the step on which the second LED 110 is provided.

[0045] The arrangement of the lighting module 102 with respect to the reflector 104 within the lighting apparatus 400 shown in FIG.4A may be modified in that the lighting module 102 may be rotated to a different position, for example the position as illustrated in FIG.4B. In the embodiment of the lighting apparatus 400 shown in FIG.4B, the glare cutter 120 includes an edge portion 120 of the step on the base plate 106 separating the first LED 108 from the second LED 110, wherein that edge portion 120 may be located on an outer edge of the step. The rotation of the lighting module 102 by a certain angle may be used to adjust the distribution of the light beams output by the lighting apparatus 400 according to various embodiments. This effect may prove helpful in compensating for loads which might be put on vehicle (usually the loading space or trunk thereof which is mostly located in the back of the vehicle) and might raise its front thereby increasing the danger of light being cast into the eyes of other road users. [0046] From a "topological" point of view, the adjustment of step height between the first LED 108 and the second LED 110 in combination with a rotation of the lighting module 102 is equivalent to adjusting the tilt angle between the light emitting surfaces of the LEDs in the embodiments of the lighting apparatus shown in FIG. l and FIG.2A, for example. In both cases, the glare cutter 120 helps forming a light distribution for a low beam and a high beam and is formed by portions or edges of the base plate 106.

[0047] A further embodiment of the lighting apparatus according to various embodiments is shown in FIG.5A (front view) and FIG.5B (cross-section). The reflector 104 in the exemplary lighting apparatus 500 shown in FIG.5 A has a spherical shape, wherein the sphere has a certain radius 502. The upper dashed part of the circumference of the sphere is just marked for convenience, the reflector 104 only includes the continuous part of the sphere. In the front view of the lighting apparatus 500, only a small fraction of the base plate 106 is visible. In the cross-sectional view shown in FIG.5B, the light module 102 may be placed approximately half the radius 502 (corresponds to distance marked A) offset upwards and two thirds of the radius 502 (corresponds to the distance marked B) offset rearwards from the center of the sphere. In this exemplary embodiment of the lighting apparatus 500, the radius 502 of the sphere may be between 25 and 100 millimetres, for example 50 millimetres. Further indicated are viewing angles 504 of the LEDs which may be, for example, in the range between 70° and 140°, for example 120°. An inclination angle 506 defining the angle between a horizontal (parallel to the marked radius 502) and a beam of the first LED 108 delimiting its viewing angle may have, for example, a typical value of 5° to 20° , for example 10°. [0048] Apart from the parabolic reflector 504 shown in previous embodiments of the lighting apparatus according to various embodiments and the spherical reflector 504 shown in FIG.5A and FIG.5B, the reflector 104 is not restricted to those forms but may be designed in accordance with the desired pattern of the light distribution for the low beam and the high beam.

[0049] One of the important aspects which have to be considered when constructing lamps on the basis of LEDs is thermal management. In the following, basic

considerations with regard to thermal design of LED systems will be presented.

[0050] The first step during the design of a LED system is the determination of the required luminous flux, a measure of the total "amount" of visible light emitted by a light source which is measured in lumen (lm). For most cases, the required luminous flux P out (in lm) is determined by regulations and/or the customer specification. In the following, an emission efficiency of the LED of κ in lm/W will be assumed. This parameter may be limited by various factors such as the materials chosen during the manufacturing of the LED, the structure of the LED and/or the color rendering index. However, a realistic maximal efficiency is approximately around 200 lm/W, if exclusive special enhancing methods like the use of photonic crystals or the use of quantum dots etc. are excluded. At present, most LEDs for forward lighting have an efficiency of approximately 50 to 80 lm/W. In any case, the power input P in required for the LED to produce the required luminous flux P out amounts to

P in = P out / K.

So for example, when a luminous flux of 400 lm is necessary, a power input P in of 5 to 8 W may be required. In case the lighting apparatus according to various embodiments is used as a motorcycle head lamp, the power input might double to a maximal power input of 16 W, since motorcycle head lamps are configured such that both the low beam and the high beam may be switched on at the same time.

[0051] During the operation of an LED, the generation of heat at its junction causes the junction to heat up. There is a rated maximal temperature of the junction of the LED, denoted with TJ max (in °C). Another important characteristic in this respect is the thermal resistance of the LED, denoted with Rth (in K/W). Both these parameters are measured and defined by the manufacturer of a respective LED. Owing to the provision of operation current at the junction, its temperature raises from ambient temperature T amb (in K). When the junction temperature exceeds the rated maximal junction temperature TJ max, the lifetime of the LED is drastically decreased. It is therefore a substantial goal to design the LED such that the junction temperature of the operated LED always remains below or exceeds as seldom and/or little as possible the rated maximal junction temperature T_j_max. Unfortunately, an actual measurement of the junction temperature T_j_set (in K) is rather difficult. Therefore, the LED system designer usually estimates a junction temperature T_j_est (in K) by the following equation:

TJ est = (Rth + Rmod + Rhs)-P_in+ T amb

In the above equation, Rmod denotes a thermal resistance of the internal LED module and Rhs denotes a thermal resistance of the heat sink to air , wherein the thermal resistance of the internal LED module Rmod is determined by the LED module design of the light source module manufacturer. In general, the goal is to keep the junction temperature below the rated maximal junction temperature, TJ est < TJ max. When realistic values are assumed for the thermal resistance of the internal LED module and the heat sink to air capacity, a sum of hose two values below 2 K/W may be obtained, i.e. Rmod + Rhs < 2 K/W. To compensate for the worst case scenario, Rmod < 1 K/W is desirable since it is quite difficult to obtain heat sinks with Rhs < 1 K/W.

[0052] As already mentioned, aluminium alloy among other materials may be used for the base plate 106 of the LED module 102, mainly due to reasons of

manufacturability, productivity, costs, etc. Thermal conductivity of aluminium alloy is roughly 120 to 237 W/ (m-K). In order to ensure a sufficient transport of heat from the LEDs to the heat sink 114 through the base plate 106, an exemplary base plate 106 mainly including aluminium alloy may have a cross sectional area of 15 mm². In that case, the length of base plate 106 should be smaller than 33 mm². This value may be obtained from theoretical calculations based on exemplary lighting module 600 shown in FIG.6A or FIG.6B. As can be seen, the base plate 106 comprises a rectangular shape with a step on its top, on which the second LED 110 is arranged. In this sense, the exemplary lighting module 600 is similar to the lighting modules shown in the embodiments of lighting apparatuses 400 in FIG.4A and FIG.4B. The base plate 106 is removably connectable or insertable into the heat sink 114. The previously used length of the base plate corresponds to the dimension denoted by the first arrow 602, the area of the base plate is the cross sectional area (seen in projected view from the top) denoted with the second arrow 604.

[0053] From the theoretical considerations presented above, a lighting module 600 may be designed which has a length of the base plate that is less than 30 mm. Furthermore, the lighting apparatus according to various embodiments allows the use of a heat sink with heat sink capacity to air of less than 1 K/W.

[0054] The lighting apparatus according to various embodiments may include a heat sink 114 which is thermally connected to the base plate 106. As for now, in common LED lighting systems the heat sink is attached to the back of the LEDs or the back of the base platel06, as also shown in FIG.6B. As can be seen in FIG.6A, for example, the first LED 108 and the second LED 110 are mounted on a common base plate 106 such that a thermally conductive contact between the LEDs and the base plate 106 is provided. In an exemplary operation mode, when the LED producing the low beam is turned on and the LED producing the high beam is turned off, the heat generated by one LED may be transferred to the heat conductive part or the heat sink 114 via the common base plate 106. Therefore, the thermal conduction function of the common base plate 106 is shared by both LEDs.

[0055] In FIG.7A a further embodiment of the lighting apparatus 700 is shown which is based on the lighting module 600 shown in FIG.6A and FIG.6B. In this embodiment, the heat sink 114 is provided in the form of a heat radiating plate 114 which may radially extend from the base plate 106. The heat sink 114 may a attached to any thermally conductive area of the lighting module 106. The encircled region 702 denotes the contact area between the heat sink 114 and the base plate 106 or any thermally conductive area of the lighting module 106 and is shown in an enlarged view in FIG.7B. The contact between the heat sink 114 and the base plate 106 includes a slanted or tapered contact 704, such that a contact surface of the heat sink 114 may be slidably moved upwards or downwards on a corresponding contact surface of the base plate 106, wherein the contact surface of the heat sink 114 and the contact surface of the base plate 106 form the tapered contact 704. A recess 708 may be provided on one end of the tapered contact 704, for example on the end lying closer to the LED modules, wherein the recess might extend circumferentially around the base plate 106. In the recess 708, an O-ring 706 may be provided as a sealing mechanism. The O-ring may comprise any heat endurable material, for example heat endurable elastomer. The contact surface of the heat sink 114 and the contact surface of the base plate 106 may be in direct contact with each other. However, heat-conductive paste may be provided in the tapered contact 704, i.e. between the contact surface of the heat sink 114 and the contact surface of the base plate 106 in order to enhance the thermal flow from the base plate 106 to the heat sink 114. The tapered contact 704 may be also helpful for precise positioning of the heat sink 114 with respect to the base plate 704 or the lighting module.

[0056] In the following, the photometric performance of the lighting apparatus according to various embodiments will be described. In general, the light emitting area is an extended finite one, although from a designer's point of view, a point light source would be desirable. With the presently available technology with regard to the available luminous flux density in LEDs, a light emitting area of approximately 2 mm² or even larger is necessary to obtain a luminous flux on the order of 500 lumen which, for example, is stipulated by regulations for vehicle design such as ECE, SAE, JIS etc. For manufacturing reasons, a rather small reflector is desirable. For example, a diamater in the range between 10 mm and 15 mm may be desirable for a 2- wheel head lamp.

[0057] One of the crucial factors affecting the optical performance of a lamp is the mechanical positioning of its components, especially manufacturing tolerance. In general, a mechanical positioning tolerance or a mechanical manufacturing tolerance of approximately +/- 2 mm may be assumed as the worst case in ordinary manufacturing processes.

[0058] In order to asses the effect of positioning and/or manufacturing tolerances on the photometric performance of various embodiments of the lighting apparatus, simulations have been performed. In FIG.8A, the underlying theoretical model is displayed. Here a parabolic reflector 104 is assumed which reflects and collimates light rays 804 emitted by a light source located within the reflector 104 (not visible in FIG.8A). At a certain distance, a detector plane 802 is set up and an intensity profile created by light rays 804 is recorded. In FIG.8B, an enlarged view of the reflector 104 is shown such that the model light source 806 is also visible. An origin of a system of axes of coordinates 808 is coincides with the light source. A z-axis 814 of the system of axes of coordinates 808 coincides with the symmetry axis of the reflector 104, an x-axis 810 and a y-axis 812 define a plane lying perpendicular to the z-axis, i.e. the symmetry axis of the reflector 104.

[0059] In FIGS. 9A through 9F and in FIGS.1 OA through 10J the results of the simulations based on the model shown in FIG.8A and FIG.8B is shown. For the simulations, a reflector focal length of 15 mm has been assumed and the distance between the reflector 104 and the detector plane amounts to 1 m.

[0060] In FIGS. 9A through 9F, the effect of the light source 806 being shifted from the focal point of the reflector 104 perpendicular to the z-axis 814 is analyzed. The diagram 900 shown in FIG.9A shows the illuminance 902 registered on the detector plane 802, wherein the x-axis 904 of the diagram 900 denotes a deviation from a center of the detector plane 800 in millimetres and the y-axis 906 of the diagram 900 denotes the value of the illuminance, in lumens/cm². The zero-value on the on the x-axis 904 corresponds to the center of the detector plane 802 and is aligned with the reflector, i.e. the symmetry axis of the reflector 104 intersects the detector plane 802 at the position of the center of the detector plane 802. The diagram 908 shown in FIG.9B shows the illuminance 910 registered on the detector plane 802, wherein the x-axis 904 of the diagram 908 denotes a deviation from the center of the detector plane 800 and the y-axis 906 of the diagram 900 denotes the value of the illuminance, in lumens/cm². The direction of the deviation from the center of the detector plane 802 represented by the x- axis 904 in diagram 908 of FIG. 9B lies perpendicularly to the direction of the deviation from the center of the detector plane 802 represented by the x-axis 904 in diagram 900 of FIG. 9A. In other words, the diagram 902 shown in FIG.9A shows the illuminance distribution along a first axis parallel to the x-axis 810 of the system of coordinate axes 808 on the detector plane 802 and the diagram 910 shown in FIG.9B shows the illuminance distribution along a second axis parallel to the y-axis 810 of the system of coordinate axes 808 on the detector plane. In the simulations resulting in the illuminance profiles as displayed in FIG.9A and FIG.9B, the light source is located at the focal point of the reflector 104. Consequently, owing to the symmetry of the reflector 104, the illuminance profiles shown in FIGS.9A and 9B, apart from negligible aberrations, are the same.

[0061] Diagram 912 shown in FIG.9C and diagram 916 shown in FIG.9D

correspond to the diagram 900 shown in FIG.9A and the diagram 908 shown in FIG.9B. However, in these cases, the light source 806 is placed off the z-axis 814 by 100 μηι, i.e. the light source 806 is displaced from its original position at the focal point of the reflector 104 (results presented in FIG.9A and FIG.9B) by 100 μηι along the x-axis 810. As can be seen in diagram 912 shown in FIG.9C, the illuminance 914 does not have a symmetrical form any more, the illuminance maximum is shifted away from the center of the detector plane 802 when compared with the corresponding illuminance 902 shown in diagram 900 of FIG.9 A, where the light source 806 is placed at the focal point of the reflector.

[0062] Diagram 920 shown in FIG.9E and diagram 924 shown in FIG.9F

correspond to the diagram 900 shown in FIG.9A and the diagram 908 shown in FIG.9B. However, in these cases, the light source 806 is placed off the z-axis 814 by 200 μηι, i.e. the light source 806 is displaced from its original position at the focal point of the reflector 104 (results presented in FIG.9A and FIG.9B) by 200 μηι along the x-axis 810. As can be seen in diagram 920 shown in FIG.9E, the illuminance 922 does not have a symmetrical form any more, the illuminance maximum is shifted away from the center of the detector plane 802 when compared with the corresponding illuminance 902 shown in diagram 900 of FIG.9 A, where the light source 806 is placed at the focal point of the reflector. Owing to the off-axis displacement of 2 mm, the illuminance 922 shown in diagram 920 of FIG.9E has a stronger degree of asymmetry as compared with the illuminance 914 shown in diagram 912 of FIG.9C, such that the maximum value of the illuminance lies at greater distance from the center of the detector plane 802.

[0063] In the simulation results discussed above, the-off center displacement by 200 μηι corresponds to a deviation angle between the direction towards the maximum illuminance on the detector plane 802 and the center of the detector plane 802 of 1,4 degrees. Such a deviation may be compensated by an head lamp tilt adjusting mechanism which is present in almost all motorcycles.

[0064] In FIGS.1 OA through 10 J, results of further simulations are shown, based on the model described in FIG.8 A and FIG.8B. For these simulations a reflector focal length of 15 mm has been assumed and the distance between the reflector 104 and the detector plane amounts to 1 m, just as was the case for the simulation results shown in FIGS.9A through 9F.

[0065] The structure of diagrams shown in FIGS.1 OA through 10J is analogous to the structure of the diagrams shown in FIGS.9A through 9F. That is, the diagram 1000 shown in FIG.10A shows the illuminance 1002 of the reflector 104, wherein the x-axis 1004 denotes a deviation from the center of the detector plane 800 in millimetres and the y-axis 1006 denotes the value of the illuminance in lumens/cm². The zero-value on the on the x-axis 1004 in diagram 1000 corresponds to the center of the detector plane 802 and is aligned with the reflector 104, i.e. the symmetry axis of the reflector 104 intersects the detector plane 802 at the position of the center of the detector plane 802. The diagram 1008 shown in FIG.10B shows the illuminance 1010 registered on the detector plane 802, wherein the x-axis 904 denotes a deviation from the center of the detector plane 800 in millimetres and the y-axis 1006 denotes the value of the illuminance, in lumens/cm². The direction of the deviation from the center of the detector plane 802 represented by the x-axis 1004 in diagram 1008 of FIG. 10B lies perpendicularly to the direction of the deviation from the center of the detector plane 802 represented by the x-axis 1004 in diagram 1000 of FIG. 1 OA. In other words, the diagram 1000 shown in FIG.1 OA shows the illuminance distribution 1002 along a first axis parallel to the x-axis 810 of the system of coordinate axes 808 on the detector plane 802 and the diagram 1008 shown in

FIG.10B shows the illuminance distribution 1100 along a second axis parallel to the y- axis 810 of the system of coordinate axes 808 on the detector plane 802. In the simulations resulting in the illuminance profiles as displayed in FIG.1 OA and FIG.10B, the light source is located at the focal point of the reflector 104. Consequently, owing to the symmetry of the reflector 104, the illuminance profiles shown in FIGS.1 OA and 10B, apart from negligible aberrations, are the same.

[0066] Diagram 1012 shown in FIG.10C and diagram 1016 shown in FIG.10D correspond to the diagram 1000 shown in FIG.1 OA and the diagram 1008 shown in FIG.10B, respectively. However, in these cases, the light source 806 is displaced from the focal point of the reflector 104 by -100 μηι along the z-axis 814, i.e. the light source 806 is displaced from its original position at the focal point of the reflector 104 (results presented in FIG.1 OA and FIG.10B) by 100 μηι in the negative direction along the z-axis 814. As can be seen in diagram 1012 shown in FIG. IOC and diagram 1016 shown in FIG.10D, the illuminance distribution flattens out and the maximal illuminance drops to a lower value when compared to the corresponding illuminance 1002 and/or illuminance 1100 shown in diagram 1000 of FIG.1 OA and/or FIG.10B, where the light source 806 is placed at the focal point of the reflector 104. Since the light source 806 is still located on the symmetry axis of the reflector 104 (corresponds to z-axis 814 of the system of coordinate axes 808), the illuminance distribution in diagram 1012 and in diagram 1016 are the same apart from negligible aberrations.

[0067] Diagram 1020 shown in FIG.10E and diagram 1024 shown in FIG.1 OF correspond to the diagram 1000 shown in FIG.1 OA and the diagram 1008 shown in

[0068] Diagram 1028 in FIG.10G and diagram 1032 in FIG.10H correspond to the diagram 1012 shown in FIG. IOC and the diagram 1016 in FIG.10D. However, in these cases the light source 806 is displaced from the focal point of the reflector 104 by 100 μηι along the z-axis 814, i.e. the light source 806 is displaced from its original position at the focal point of the reflector 104 (results presented in FIG.1 OA and FIG.10B) by 100 μηι in the positive direction along the z-axis 814. In an analogous manner, diagram 1036 in FIG.101 and diagram 1040 in FIG.10J correspond to the diagram 1020 shown in FIG. IOE and the diagram 1024 in FIG.1 OF. However, in these cases the light source 806 is displaced from the focal point of the reflector 104 by 200 μηι along the z-axis 814, i.e. the light source 806 is displaced from its original position at the focal point of the reflector 104 (results presented in FIG.1 OA and FIG.10B) by 200 μηι in the positive direction along the z-axis 814. It can be seen from the diagrams that displacing the light source 806 from the focal point along the z-axis 814, i.e. towards positive z-values, results in an increase in illuminance peak value, for example an increase in illuminance peak value by approximately 36% in the case of a displacement of the light source 806 from the focal point of the reflector 104 by 200 μπι. Since the light source 806 remains located on the symmetry axis of the reflector 104 (corresponds to z-axis 814 of the system of coordinate axes 808), the illuminance distribution in diagram 1028 and in diagram 1032 (and/or in diagram 1036 and in diagram 1040) are the same, apart from negligible aberrations.

[0069] Overlooking the simulation results just discussed, it may be advantageous to keep the maximum mechanical tolerance below 200 μπι.

[0070] In FIG.ll, a further embodiment of the lighting module 1100 is shown. The first LED 108 and the second LED 110 may be mounted or arranged on a common base plate 106. The height of the step separating the first LED 108 from the second LED 110 may be properly determined, for example determined such that a sufficient glare cutter functionality is provided. For example, the step length, i.e. the distance between the first mounting surface 122 and the second mounting surface 124, may be 5 mm. The distance between the LEDs, which corresponds to the distance between the LEDs when the lighting module 1100 is seen from top in projected view, may be also 5 mm and each of the LEDs may have a light generating surface area of approximately 2 mm². When the step length is greater than 7 mm, for example, light from the first LED 108 may be reflected on a wall 126 of the step which may increase the optical efficiency. However, seen from the optical design point of view, the total optical design may become more complex and the acceptable tolerance margin with regard to the positioning of the LEDs may become more narrow, as the portion of light reflected by the wall 126 of the step is more difficult to deal with seen from the optical design point of view. In order to avoid possible problems of this kind, the reflection off the wall 126 of the step may be reduced, for example by coating it with a material of a low reflectivity, i.e. a material that absorbs a substantial part of the light of the respective LED that impinges on it. In general, approximately 20% of the heat generated by either one or both of the LEDs may be radiated through the baste plate 106, the rest of the heat may be transported to the heat sink (not displayed in FIG.11). The base plate 106 may be surrounded by a housing 302 which may be of circular shape. A connector 116 may be attached to the bottom of the housing 302.

[0071] The lighting apparatus according to various embodiments may further include an LED driver which may be configured to operate the LED according to current needs, such as road conditions, for example if the lighting apparatus according to various embodiments is used as a head lamp in a 2-wheel or a 4-wheel vehicle.

[0072] An exemplary embodiment of an LED driver circuit 1200 is shown in FIG.12. The LED driver circuit 1200 may include an input filter 1208 having a first input 1202, to which a supply potential may be connected, and a second input 1204, to which a reference potential, for example the ground potential, may be connected. The input filter 1208 may have components such as capacitors and resistors arranged such that they may provide filtering functionality with respect to disturbances which may be present on the supply potential or the ground potential. The input filter 1208 may be further coupled to the ground potential via an AC couple capacitor 1210 providing a short circuit path for AC current and/or voltage components which may be present on the supply potential. The input filter 1208 may have an output 1214 which may be connected to a first input 1224 of a DC/DC converter 1218 (in the following: converter) of the LED driver circuit 1200 via a protection diode 1216.

[0073] The converter 1218 may, for example, be a configured as a buck converter. The converter 1218 may have a second input 1222 which may be connected to a high beam low beam selection port 1206 and the converter 1218 may be connected to the reference potential, for example the ground potential, via a terminal 1220. The converter 1218 may have a third input 1226 to which an output of a derating module 1234 may be connected. The derating module 1234 may be connected to a temperature sensor 1236 which may, for example, comprise a NTC (negative temperature coefficient) resistor. The converter 1224 may include a first terminal 1228 and a second terminal 1232. A series arrangement of the first LED 1242 and the second LED 1244 may be coupled between the first terminal 1228 and the second terminal 1232, wherein a shunt resistor 1238 may be coupled between the second terminal 1232 of the converter 1218 and the first LED 1242. The converter 1218 may include a third terminal 1230 which is coupled to a control input of a bypass switch 1240, for example a gate or a base of a transistor. The two ends of the switchable path within the bypass switch 1240 are connected in parallel to the second LED 1244.

[0074] It is pointed out that the embodiments of the LED driver circuit 1200 shown in FIG.12 may be altered such that the first LED 1242 and the second LED 1244 may be coupled in parallel between the first terminal 1228 and the second terminal 1232. It is also possible that the first LED 1244 and the second LED 1242 my be connected to the converter 1218 individually, such that the voltage applied to each of the LEDs may be individually adjusted which allows, for example, for individual adjustment of the luminous flux of each of the LEDs.

[0075] During operation, an operating current, which may be AC or DC, from the supply potential is provided to the converter 1218 via the input filter 1208 and is converted into a constant current. The constant current is then applied to the first LED 1242 and/or second LED 1244. When the lighting apparatus according to various embodiments is used as a head lamp in a 2-wheel or a 4-wheel vehicle, the current supplied to the LEDs might be limited such that the luminous flux of 400 lm is not exceeded, as required by road traffic regulations. In FIG.12, a simplified embodiment of the LED driver 1200 is shown where the current provided to the LED generating the low beam and the LED generating the high beam is the same.

[0076] The temperature sensor 1236 provides a temperature reading to the derating module 1234 which may be configured to determine whether one or both of the LEDs are overheated and in case such a state is detected, the derating module 1234 may be further configured to transmit a corresponding signal to the converter 1218 which will lower the current provided to the one or both of the LEDs. The signal provided from the high beam low beam selection port 1206 determines whether the LED generating the low beam or the LED generating the high beam is activated. However, it is also possible that both LEDs may be turned on at the same time. The second LED 1244 may be turned off by activating the bypass switch 1240, i.e. setting it into a conducting mode, whereby the current will be bypassed around the second LED 1244. It should be noted that even though the LEDs have been described together with the LED driver circuit 1200 for ease of understanding, they do not form inherent components of the LED driver circuit 1200.

[0077] In the described exemplary LED driver circuit 1200 in FIG.12, the power consumption of each LED may be approximately 10 W or less. This is a small value compared to the power consumption of typical current filament bulbs. Owing to the power consumption of 10 W or less per LED, for example, the use of the DC/DC converter 1218 is suitable. Alternatively, a linear IC (integrated circuit) may be used or a resistance bridge. However, in the latter case, the LED driver 1200 would have a larger number of self-heating in comparison with DC/DC converter.

[0078] In FIG.13, a typical example of a 2-wheel 1300 is shown. The lighting apparatus according to various embodiments may be used, for example, as a head lamp 1302 for those kinds of motorcycles.

[0079] An example of a reflector-type lamp unit 1400 based on the lighting apparatus according to various embodiments is shown in FIG.14. The lamp unit 1400 includes a housing 1402 in which a reflector 1404 is located. The lamp unit 1400 may be used, for example, as a head lamp in the motorcycle 1300 shown in FIG.13.

[0080] It is understood that even though various embodiments of the lighting apparatus have been described as having the light generating surface of the LEDs facing downwards, each embodiment of the lighting apparatus described in this application may be just as well be provided with the light generating surface of the LEDs facing upwards, i.e. the whole arrangement may be rotated by 180°. [0081] While the invention has been particularly shown and described with reference to specific embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. The scope of the invention is thus indicated by the appended claims and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced.

Claims

Claims What is claimed is:

1. A lighting apparatus comprising:

a reflector; and

a lighting module comprising:

a base plate;

a first light generating element arranged on the base plate such that light emitted by the first light generating element illuminates a first portion of a surface of the reflector; and

a second light generating element arranged on the base plate such that light emitted by the second light generating element illuminates a second portion of the surface of the reflector;

wherein a light emitting surface of the first light generating element is tilted with respect to a light emitting surface of the second light generating element.

2. Lighting apparatus according to claim 1,

wherein the first portion of the surface of the reflector and the second portion of the surface of the reflector are free of an overlap.

3. Lighting apparatus according to claim 1 or 2, wherein an edge portion is provided on the base plate such that it blocks a part of the light emitted by the first light generating element and/or second light generating element.

A lighting apparatus, comprising:

a reflector; and

a lighting module comprising:

a base plate;

a first light generating element arranged on the base plate such that light emitted by the first light generating element illuminates a first portion of the surface of the reflector; and

a second light generating element arranged on the base plate such that light emitted by the second light element illuminates a second portion of the surface of the reflector;

wherein a light emitting surface of the first light generating element is arranged at a distance from and parallel to a light emitting surface of the second light generating element.

Lighting apparatus according to claim 4,

wherein an edge portion is provided on the base plate such that it blocks a part of the light emitted by the first light generating element and/or second light generating element, the edge portion being formed as an edge of a step separating the first light generating element form the second light generating element.

6. Lighting apparatus according to claim 4 or 5,

wherein the light emitting surface of the first light generating element and/or the light emitting surface of the second light generating element is arranged at an angle with respect to an optical axis of the reflector.

7. Lighting apparatus according to any of the claims 1 to 6,

wherein the first light generating element and the second light generating element are light-emitting diodes.

8. Lighting apparatus according to any of the claims 1 to 7,

wherein the first light generating element and the second light generating elements are arranged on a first mounting surface and a second mounting surface of the base plate, respectively.

9. Lighting apparatus according to any of the claims 1 to 8,

wherein the first portion of the surface of the reflector and the second portion of the surface of the reflector overlap.

10. Lighting apparatus according to any of the claims 1 to 9,

wherein the reflector comprises a portion of a paraboloid of revolution.

11. Lighting apparatus according to any of the claims 1 to 9, wherein the reflector comprises a portion of a sphere.

12. Lighting apparatus according to any of the claims 1 to 11,

wherein the lighting module is arranged at a focal point of the reflector.

13. Lighting apparatus according to any of the claims 1 to 12,

wherein the lighting module further comprises a heat sink.

14. Lighting apparatus according to claim 13,

wherein the base plate is removably connected to the heat sink.

15. Lighting apparatus according to claim 13 or 14,

wherein the heat sink comprises heat radiation plates which are connected to the base plate.

16. Lighting apparatus according to claim 15,

wherein the heat radiation plates are connected to the base plate through a thermally conducting sloped contact.

17. Lighting apparatus according to any of the claims 1 to 16,

further comprising:

a light generating element driver which is electrically connected to the first light generating element and/or the second light generating element and is configured to operate the first light generating element and/or second light generating element.

18. Lighting apparatus according to claim 17,

wherein the light generating element driver is configured to allow a current to simultaneously flow through the first light generating element and the second light generating element.

19. Lighting apparatus according to any of the claims 1 to 18,

wherein the first light generating element and the second light generating element are connected in series.

20. Lighting apparatus according to any of the claims 1 to 19,

wherein the lighting module further comprises an electrical connector.