Light emitting device

Abstract

A light emitting device is provided comprising: a body; a base portion configured for mounting the light emitting device to a reflector of a headlight or taillight, the base portion being arranged at a first end portion of the body; at least one light-emitting diode arranged at or inside of the body; at least one infrared light source provided at the body and configured to emit infrared light; and a thermal barrier arranged in between the at least one infrared light source and the at least one LED and configured to block at least part of radiation emitted from the at least one infrared light source towards the at least one LED.

Claims

1. A light emitting device comprising: an elongated body having oppositely disposed first and second end portions that define a longitudinal axis; a base portion configured for mounting the light emitting device to a reflector of a headlight or taillight, the base portion being attached to the first end portion of the body; at least one light-emitting diode, abbreviated LED, arranged at or inside an intermediate portion of the body between the first and second end portions; at least one infrared light source attached to the second end portion of the body, the at least one infrared light source being configured to emit infrared light; and an infrared reflector positioned along the longitudinal axis at the second end portion of the body, the infrared reflector being arranged so as to act as a thermal barrier arranged in between the at least one infrared light source and the at least one LED, the infrared reflector being configured to block at least a portion of infrared light emitted the at least one infrared light source that propagates towards the at least one LED.

2. The light emitting device according to claim 1, wherein the second end portion of the body comprises an inwardly curved portion at least partially curved towards the first end portion and towards the at least one LED, the infrared reflector is formed on at least a portion of the inwardly curved portion, and the at least one infrared light source is at least partially received within the inwardly curved portion of the second end portion.

3. The light emitting device according to claim 1, wherein the at least one infrared light source comprises at least one light-emitting diode or at least one filament.

4. The light emitting device according to claim 1, wherein the infrared light comprises at least one wavelength equal to or larger than 750 nm.

5. The light emitting device according to claim 1, wherein the at least one LED and the at least one infrared light source are electrically connected in series.

6. The light emitting device according to claim 5, further comprising a linear regulator connected in series in between the at least one LED and the at least one infrared light source.

7. A lighting system comprising: a light emitting device according to claim 1, and a visible reflector, wherein the light emitting device is mounted to the visible reflector via the base portion, the visible reflector is configured to reflect at least a portion of light emitted from the at least one LED at least in a main lighting direction, the main lighting direction being substantially parallel to the longitudinal axis, and the at least one infrared light source is configured to emit at least a portion of the infrared light at least in the main lighting direction.

8. The lighting system according to claim 7, comprising: a controller configured to control operation of the at least one infrared light source, a first sensor comprising at least one of: a temperature sensor configured to detect an ambient temperature, and a sensor configured to detect ice or humidity present on an outside surface of a light exit face of the lighting system, and a second sensor configured to measure a voltage applied to the at least one LED, or to the at least one infrared light source, or to the light emitting device; wherein the controller is configured to control an operation of the at least one infrared light source based on an output of the first sensor or on an output of the second sensor.

9. The lighting system according to claim 7, comprising a cooler configured to cool the at least one LED.

10. The lighting system according to claim 9, wherein the cooler is electrically connected in series with the at least one LED.

11. The lighting system according to claim 7, wherein the visible reflector is configured to reflect light emitted from an H4 or H7 halogen lamp mounted to the visible reflector, and the light emitting device is configured as a replacement for an H4 or H7 halogen lamp.

12. The lighting emitting device according to claim 1, the infrared reflector being concave.

13. The lighting emitting device according to claim 1, the infrared reflector being arranged so as to (i) redirect at least a portion of infrared light emitted by the at least one infrared light source to propagate away from the second end portion of the body along the longitudinal axis and (ii) block propagation of light emitted by the at least one LED away from the second end portion of the body along the longitudinal axis.

14. The lighting emitting device according to claim 1, the infrared reflector being concave and arranged so as to (i) redirect at least a portion of infrared light emitted by the at least one infrared light source to propagate away from the second end portion of the body along the longitudinal axis and (ii) block propagation of light emitted by the at least one LED away from the second end portion of the body along the longitudinal axis.

15. The lighting emitting device according to claim 1, wherein the light emitting device is configured as a replacement for an H4 or H7 halogen lamp.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Examples of the invention will now be described in detail with reference to the accompanying drawing, in which:

(2) FIG. 1 shows an exemplary cross-sectional view of a lighting system incorporating a halogen lamp;

(3) FIG. 2 shows an exemplary cross-sectional view of the halogen lamp of FIG. 1;

(4) FIG. 3 shows an exemplary cross-sectional view of an embodiment of an inventive light emitting device; and

(5) FIG. 4 shows an exemplary circuit diagram of an embodiment of connecting the at least one LED and the at least one infrared light source in series.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(6) FIG. 1 shows an exemplary cross-sectional view of a headlight 100 or headlamp 100 with a reflector 141 to which a halogen lamp 110, in the shown case, a H7 lamp 110, is mounted. As illustrated, a main light source 111 of the halogen lamp 110 is thereby placed at or near the focus of reflector 141 such that light (illustrated by light rays, two of which are labeled 132) emitted from said main light source 111 is reflected by the reflector 141 into a main lighting direction 150. Headlight 100 further comprises a cover 143 which may incorporate light guiding capabilities, i.e., which may for example comprise one or more lenses, Fresnel optics, diffusers or prisms. In the shown case, the parallel light rays reflected from the inner reflector surface are bent downwardly by said cover 143. Two of the bent light rays are exemplarily labeled 133.

(7) FIG. 2 illustrates halogen lamp 110 of FIG. 1 in an enlarged view. As shown, the halogen lamp comprises a body 116 which is mounted to a base portion which in the shown case comprises a plug portion 117, a flange portion 119 and a support portion 118. As can be taken from FIG. 1, with the support portion 118 and the flange portion 119, the base portion is configured for mounting the halogen lamp 110 to headlight 100. FIG. 2 further schematically illustrates the main light source 111, which (as in the case for example of a H4 or H7 lamp) is mounted inside of body 116. Body 116 may have an essentially circular cross-section. The main light source may in the case of a halogen lamp such as a H4 lamp comprise a filament for generating a high beam and a filament for generating a low beam, the filaments being connectable to an electrical power source via pins 115 (only one labeled in the figure). Body 116 may in the shown case correspond to a hollow body such as a bulb or envelope filled with a suitable gas and formed by a suitable transparent material such as quartz glass. Body 116 is mounted to the support portion 118 at a first end portion 120 thereof and comprises an antiglare cap 112 provided at a second end portion 121 thereof to block direct light emitted from the main light source 111 and to allow for the headlight emitting an essentially even light beam without hotspot in the center.

(8) FIG. 3 illustrates a light emitting device 210 in accordance with an embodiment of the first aspect of the present invention. As can be taken from FIG. 3, the light emitting device 210 is essentially based on the halogen lamp 110 illustrated in FIG. 2 and thus corresponds to a retrofit lamp retrofitting for example a H7 halogen lamp. In other words, the light emitting device 210 may replace halogen lamp 110 of FIG. 1 being mounted to reflector 141 to thus form a lighting system according to an embodiment of the second aspect of the present invention.

(9) As shown, the light emitting device 210 comprises a base portion with a plug portion 217 with two pins 215, a flange portion 219 and a support portion 218. Said base portion is configured for mounting the light emitting device 210 to a headlight as for example shown in FIG. 1, and is arranged at a first end portion 220 of a body 216 of light emitting device 210. In other words, body 216 is mounted to the base portion at its first end portion 220. In another example, body 216 may be connected indirectly to the base portion or may be integrally formed with the base portion.

(10) The shown body 216 is an essentially plate like flat member of a suitable material such as a suitable plastic or metal material. The shown main light source 211 schematically shows the at least one LED which is arranged on a front surface of body 216. While the schematic illustration shows a single light source 211, more than one LED may be positioned at or around the position of main light source 211. For example, three or four LEDs may be positioned along the position of main light source 211. While not visible in the figure, on a surface of body 216 opposing the visible front surface, further one or more LEDs, e.g. three or four LEDs, e.g. on a position corresponding to the position indicated by main light source 211, may be provided. It is noted that in an alternative embodiment not illustrated, body 216 may essentially correspond to body 116 of FIG. 2, i.e. may correspond to a bulb or envelope for example made of glass or another suitable transparent material. In this case, the main light source 211, i.e. the at least one LED, may be provided inside of body 216. In different embodiments, body 216 may have a different shape with a different cross-section but may nevertheless be suitable to support the at least one LED. The main light source 211 (the at least one LED) may correspond to one LED or to an array of plural LEDs and is provided at a position inside of body 216 such that in mounted condition of the light emitting device 210 in a reflector (e.g. reflector 141), the main light source 211 is placed at or close to a focus of the reflector.

(11) As further shown in FIG. 3, an infrared light source, in the shown case an infrared filament 214 housed by a filament bulb 213, is arranged at a second end portion 221 of body 216, which second end portion 221 is opposite to the first end portion 220 of body 216. The infrared light source, i.e. the shown filament, is mounted to body 216 via two wires which extend from the infrared filament 214 onto respective surfaces (the shown front surface and the non-visible surface opposing the front surface) of body 216. These wires serve for holding the infrared filament at body 216 and for electrically connecting the infrared filament. An illustration of the wires is omitted to keep the figure concise. It is noted that the particular way of mounting the infrared filament to body 216 is not an essential feature and that multiple ways of mounting the infrared filament to body 216 are apparent for a person skilled in the art.

(12) It is noted that the figures illustrate use of a single infrared filament with corresponding filament bulb for simplicity of the illustration. In accordance with embodiments of all aspects of the invention, one or more infrared light sources such as one or more infrared filaments with corresponding bulbs and/or one or more infrared LEDs may be comprised by the light emitting device and/or by the lighting system.

(13) In the shown example, the infrared light source is an infrared filament housed by a filament bulb 213. The infrared light source is provided at body 216 via said filament bulb 213, which is mounted to body 216 in a convenient manner not illustrated in the figure. For example, a suitable holder (not shown), made for example from a metal or a heat resistant plastic material, can be provided in a way that one of its sides is attached to the filament bulb 213 and that another one of its sides is attached to the second end portion 221 of body 216. As can be taken from the figure, being mounted in this way at the second end portion 221, infrared light emitted from the infrared filament 214 is emitted essentially along the main lighting direction 250 of a lighting system (for example a lighting system part of which is illustrated in FIG. 1) to which the light emitting device 210 is mounted.

(14) In order to protect the main light source 211, i.e. the at least one LED, from heat radiation emitted from infrared filament 214, a thermal barrier 224 is arranged in between the infrared filament 214 and the at least one LED 211, which is configured to block at least part of radiation emitted from the infrared filament 214 towards the at least one LED 211. This thermal barrier or isolator may be a component like a thin metal plate configured to block infrared radiation.

(15) Further, a reflector 212 is arranged in between the infrared filament 214 and the at least one LED 211 and is configured to reflect radiation, emitted from the infrared filament 214, essentially into the main lighting direction 250. As can be taken from FIG. 3, in the shown case, said reflector 212 corresponds to a sheet or coating formed at least partially on an outer surface of an inwardly curved portion formed within the second end portion 221 which is curved towards the first end portion 220 and towards the at least one LED 211. The reflector 212 may for example be a metal sheet or metal coating such as a silver, gold or aluminum coating. In an alternative exemplary embodiment (not shown), the reflector 212 may be formed at least partially on an outer surface of the filament bulb 213 adjacent to the inwardly curved surface of the second end portion 221. Such reflector may similarly be formed as a coating (e.g. a metal coating) on the outer surface of the filament bulb 213. Referring back to FIG. 3, as shown, the infrared light source, in particular the filament bulb 213 is at least partially received by the inwardly curved portion of the second end portion 221. In other words, the infrared light source is thus arranged within a space formed by the inwardly curved portion making the construction compact and robust. As mentioned above, the infrared light source may in addition or alternatively comprise at least one LED configured to emit infrared light, whereby infrared light corresponds to electromagnetic radiation comprising at least one wavelength equal to or larger than 750 nm.

(16) The at least one LED and the infrared light source may be electrically connected in series for example in between pins 215 (only one labeled in FIG. 3) of plug portion 217. As explained above, thereby, the infrared light source may serve as current limiting device to protect the at least one LED against current peaks which may arise for example in a case an engine of a vehicle to which the light emitting device is mounted is started. As further mentioned above, a linear regulator may be provided connected in series between the at least one LED and the infrared light source in order to further reduce the risk of current peaks acting on the at least one LED. FIG. 4 shows an example of a system 300 with a suitable linear regulator 330. Linear regulator 330 incorporates a current source 333, an operational amplifier 322 and a transistor 331. In the shown circuit diagram, reference 310 represents the at least one LED 211 of FIG. 3 and reference 320 represents the (at least one) infrared filament 214 of FIG. 3 connected in series to linear regulator 330, which in turn is connected at its two different further connections to ground via capacitor 350 and resistor 340. It turned out, that use of linear regulator 330 connected in this way enables the at least one LED to withstand cases in which peaks arise with voltages larger than 24 Volts.

(17) Thus, as explained above, by incorporating the infrared light source, e.g. infrared filament 214 housed by bulb 213 into a light emitting device, it becomes possible to enable deicing and/or defogging of covers of headlights and/or taillights to which said light emitting device is mounted. At the same time, a compact and robust construction is achieved which can be retrofitted suitably for automotive applications. In addition, the arrangement can be configured to achieve a suitable power consumption that allows to use the light emitting device in existing systems with conventional safety checks.

(18) The following enumerated paragraphs provide additional non-limiting aspects of the disclosure.

(19) 1. A light emitting device comprising: a body; a base portion configured for mounting the light emitting device to a reflector of a headlight or taillight, the base portion being arranged at a first end portion of the body; at least one light-emitting diode, abbreviated LED, arranged at or inside of the body; at least one infrared light source provided at the body and configured to emit infrared light; and a thermal barrier arranged in between the at least one infrared light source and the at least one LED and configured to block at least part of radiation emitted from the at least one infrared light source towards the at least one LED.

(20) 2. The light emitting device according to clause 1, wherein the at least one infrared light source is arranged at a second end portion of the body opposite to the first end portion of the body.

(21) 3. The light emitting device according to any one of clauses 1 and 2, further comprising: a reflector arranged in between the at least one infrared light source and the at least one LED and configured to reflect radiation emitted from the at least one infrared light source.

(22) 4. The light emitting device according to clause 2, wherein the second end portion of the body comprises an inwardly curved portion at least partially curved towards the first end portion and towards the at least one LED, and wherein the at least one infrared light source is at least partially received by the inwardly curved portion of the second end portion.

(23) 5. The light emitting device according to clause 4, wherein a reflector is formed at least partially on an outer surface of the inwardly curved portion of the second end portion.

(24) 6. The light emitting device according to any one of clauses 1 and 2, wherein the at least one infrared light source comprises at least one light-emitting diode or at least one filament.

(25) 7. The light emitting device according to any one of clauses 1 and 2, wherein the infrared light comprises at least one wavelength equal to or larger than 750 nm.

(26) 8. The light emitting device according to any one of clauses 1 and 2, wherein the at least one LED and the at least one infrared light source are electrically connected in series.

(27) 9. The light emitting device according to clause 8, further comprising a linear regulator connected in series in between the at least one LED and the at least one infrared light source.

(28) 10. A lighting system comprising: a light emitting device according to any one of clauses 1 and 2, and a reflector,

(29) wherein the light emitting device is mounted to the reflector via the base portion, the reflector is configured to reflect light emitted from the at least one LED at least in a main lighting direction, and the at least one infrared light source is configured to emit the infrared light at least in the main lighting direction.

(30) 11. The lighting system according to clause 10, comprising: a controller configured to control operation of the at least one infrared light source, a first sensor comprising at least one of: a temperature sensor configured to detect an ambient temperature, and a sensor configured to detect ice or humidity present on an outside surface of a light exit face of the lighting system, and a second sensor configured to measure a voltage applied to the at least one LED, or to the at least one infrared light source, or to the light emitting device;

(31) wherein the controller is configured to control an operation of the at least one infrared light source based on an output of the first sensor or on an output of the second sensor.

(32) 12. The lighting system according to any one of clauses 10 and 11, comprising a cooler configured to cool the at least one LED.

(33) 13. The lighting system according to clause 12, wherein the cooler is electrically connected in series with the at least one LED.

(34) TABLE-US-00001 TABLE 1 LIST OF REFERENCE SIGNS: 100 headlight or headlamp 110 halogen lamp 111 main light source of halogen lamp 112 antiglare cap of halogen lamp 115 electrical pins of halogen lamp 116 body of halogen lamp 117 plug portion of base portion of halogen lamp 118 support portion of base portion of halogen lamp 119 flange portion of base portion of halogen lamp 120 first end portion of body of halogen lamp 121 second end portion of body of halogen lamp 132 light rays to reflector 133 light rays after passing cover 141 reflector 143 cover of headlight 150 main light direction of halogen headlamp 210 inventive light emitting device 211 main light source 212 reflector 213 filament bulb 214 infrared filament 215 electrical pins 216 body 217 plug portion of base portion 218 support portion of base portion 219 flange portion of base portion 220 first end portion of body 221 second end portion of body 224 thermal barrier 250 main lighting direction 300 system with linear regulator 310 LED 320 infrared filament as resistor 322 operational amplifier 330 linear regulator 331 transistor 333 current source 340 resistor 350 capacitor

(35) This disclosure is illustrative and not limiting. Further modifications will be apparent to one skilled in the art in light of this disclosure and are intended to fall within the scope of the appended claims.