PHILIPS INTELLECTUAL PROPERTY & STANDARDS GMBH (Lübeckertordamm 5, Hamburg, 20099, DE)
RADERMACHER, Harald, Josef, Günther (AE Eindhoven, NL-5656, NL)
| CLAIMS: 1. A lighting arrangement (100), comprising: a first housing portion (102) having an interface (106) for connecting the lighting arrangement (100) to an electrical power supply; a second housing portion (104) having a light source (112) attached thereto; and electrical connecting means (110, 116) for electrically connecting the first housing portion (102) to the second housing portion (104), wherein one of the first or the second housing portion (102, 104) comprises a magnetically activable switch (108) and the other of the first or the second housing portion (102, 104) comprises magnetic activation means (118) for activating the switch (108), wherein in connecting the first housing portion (102) to the second housing portion (104) the switch (108) is activated for providing electrical power from the power supply to the light source (112), and wherein heat from the light source (112) exceeding a predetermined temperature level deactivates the switch (108). 2. Lighting arrangement (100) according to claim 1, wherein the magnetically activable switch is a thermal reed switch (108). 3. Lighting arrangement (100) according to claim 1 or 2, wherein the activation means comprises at least one of a magnet (118) and a magnetic conductor. 4. Lighting arrangement (100) according to any one of the preceding claims, wherein a ferromagnetic material of at least one of the switch (108) and the activation means (118) is selected such that the predetermined temperature for deactivating the switch (108) is less than the maximum allowed operation temperature of the lighting arrangement (100). 5. Lighting arrangement (100) according to any one of the preceding claims, further comprising a heat sink and means for thermally connecting the light source (112) and at least one of the switch (108) and the activation means (118) to the heat sink. 6. Lighting arrangement (100) according to any one of the preceding claims, wherein the light source comprises at least a light emitting diode (LED) (112). 7. Lighting arrangement (100) according to claim 6, wherein the LED is selected from a group comprising LEDs, OLEDs, PLEDs, and inorganic LEDs. 8. Lighting arrangement (100) according to any one of the preceding claims, wherein the interface for connecting the lighting arrangement (100) to the electrical power supply is selected from a group comprising screw thread interfaces, Bayonet interfaces and pin based interfaces. 9. A first housing portion (102), comprising: an interface (106) for allowing connection to an electrical power supply; - electrical connecting means (110, 116) for electrically connecting the first housing portion (102) to a second housing portion (104) having a light source (112) attached thereto; and a magnetically activable switch (108), wherein in connecting the first housing portion (102) to the second housing portion (104) the switch (108) is activated by magnetic activation means (118) comprised with the second housing portion (104) for providing electrical power from the power supply to the light source (112), and wherein heat from the light source (112) exceeding a predetermined temperature deactivates the switch (108). 10. First housing portion (102) according to claim 9, wherein the first housing portion (102) comprises a plurality of electrical connection means (110, 116) and a plurality of switches (108), thereby allowing for individual connection with a plurality of second housing portions (104) each having individual light source (112) characteristics. 11. First housing portion (102) according to any one of claims 9 or 10, further comprising means for receiving electrical power from the power supply and for distributing power to each of the plurality of electrical connection means (110, 116). 12. A second housing portion (104), comprising: a light source (112); electrical connecting means (110, 116) for electrically connecting the second housing portion (104) to a first housing portion (102) having an interface (106) for allowing connection to an electrical power supply; and magnetic activation means (118), wherein in connecting the first housing portion (102) to the second housing portion (104) the magnetic activation means (118) activates a magnetically activable switch (108) comprised with the first housing portion (102) for providing electrical power from the power supply to the light source (112), and wherein the switch (108) is arranged such that heat from the light source (112) exceeding a predetermined temperature deactivates the switch (108). |
TECHNICAL FIELD
The present invention relates to a lighting arrangement, specifically to a lighting arrangement comprising magnetic coding means.
BACKGROUND OF THE INVENTION
Recently, much progress has been made in increasing the brightness of light emitting diodes (LEDs). As a result, LEDs have become sufficiently bright and inexpensive, to serve as a light source in for example lighting arrangements such as lamps with adjustable color. By mixing differently colored LEDs any number of colors can be generated, e.g. white. An adjustable color lighting system is typically constructed by using a number of primary colors, and in one example, the three primaries red, green and blue are used. The color of the generated light is determined by the LEDs that are used, as well as by the mixing ratios. To generate "white", all three LEDs have to be turned on. By using LEDs it is possible to decrease the energy consumption, a requirement which is well in line with the current environmental trend.
For allowing retrofitting of conventional incandescent light bulbs having for example screw thread (e.g. E 14 and E27) or bayonet interface, with LED based light bulbs there has been proposed arrangements where control logic for the LEDs of the LED based light bulb is integrated into the base interface portion of the bulb. However, different geographical markets having different standards in relation to the general-purpose alternating current (AC) electric power supply (i.e. mains) voltage levels (e.g. 120 V and 230 V) requires the interface and control logic to be adapted accordingly.
Furthermore, in retrofitting conventional incandescent light bulbs with LED based light bulbs there is generally a limited possibility in providing cooling of the LEDs of the LED based light bulb, normally being limited to passive cooling. Consequently, when providing an LED based light bulb comprising LEDs having high output effect it is challenging to dissipate the LED generated heat as well as the control logic generated heat while keeping the junction temperatures of the LEDs and control logic well within their specification limits to ensure a long lifetime of the LED based light bulb. An example of an LED based retrofit light bulb comprising means for decreasing the junction temperature of the LEDs is provided in US 2007/242461, disclosing the use of a thermal management control feature that measures the internal operating temperature of the LED based light bulb and automatically reduces power if the lamp is exposed to extreme ambient temperature conditions or shuts off current at a specified PCB temperature, e.g., a predetermined threshold value, and automatically restarts when temperature falls below the threshold value. In an embodiment, a semiconductor temperature sensor is provided for sensing the temperature. However, the use of semiconductor temperature sensors, specifically in combination with temperature sensor electronics, has shown unreliable at the high junction temperatures of LEDs having high output effect.
Hence, there is a need for an improved lighting arrangement, such as an LED based retrofit light bulb, providing more reliable results when monitoring of the junction temperature of the LEDs as well as providing possibilities for allowing use in different geographical areas having different power supply voltage levels and bulb base interfaces.
SUMMARY OF THE INVENTION
According to an aspect of the invention, the above is at least partly met by a lighting arrangement, comprising a first housing portion having an interface for connecting the lighting arrangement to an electrical power supply, a second housing portion having a light source attached thereto, and electrical connecting means for electrically connecting the first housing portion to the second housing portion, wherein at least one of the first or the second housing portion comprises a magnetically activable switch and magnetic activation means for activating the switch, respectively, wherein in connecting the first housing portion to the second housing portion the switch is activated for providing electrical power from the power supply to the light source, and wherein heat from the light source exceeding a predetermined temperature level deactivates the switch
The general concept of the present invention is based on the fact that it may be possible to separate a lighting arrangement in at least two separate housing portions (e.g. first and second portion), and allow for at least one of these portions to comprise a magnetic switch and magnetic activation means, respectively. The use of the magnetic switch and the magnetic activation means has dual purposes and advantages. Firstly, the use of at least the magnetic switch and the magnetic activation means, respectively arranged in one of the first and the second housing portions allows for interchangeability between different versions of the first and the second housing portions in relation to both geographical differences (e.g. in relation interface of the mains and the voltage level) as well as combination of first housing portion and a plurality of different second housing portions having different set-ups regarding lighting characteristics (e.g. color, intensity, etc.) by providing different internal positioning of magnetic switches and magnetic activation means depending on for example different voltage levels and/or lighting characteristics. Accordingly, an automatic electrical configuration may be provided when connecting a first housing portion with a second housing portion. Secondly, the positioning of the magnetic switch or the magnetic activation means such that heat from the light source exceeding a predetermined temperature deactivates the switch provides at the same time for increased reliability of the lighting arrangement as the Curie effect of a magnetic material of the magnetic switch or the magnetic activation means offers the possibility to use the same configuration also for temperature protection. That is, if in result of a malfunction or bad cooling conditions, the lighting arrangement becomes too hot, the power supply to critical components of the lighting arrangement may be cut off automatically. Further advantages includes automatic turn-off of the electrical connecting means for electrically connecting the first housing portion to the second housing portion when the second housing portion is disconnected (i.e. if a magnetic switch is arranged with the first housing portion and electrically arrange in the electrical path for providing power to the second housing position), thereby increasing the electrical safety of the lighting arrangement. Additionally, by means of using the magnetic switch and the magnetic activation means it may be possible to avoid combination or non-compatible configuration, as no damage will result in case wrong housing portions are coupled together (i.e. the magnetic switch is not activated if the magnetic switch and the magnetic activation means are not correctly aligned together). In a preferred embodiment the magnetically activable switch is a thermal reed switch and in another embodiment the activation means comprises at least one of a magnet and a magnetic conductor. Accordingly, it may be possible to arrange the magnetic switch and the magnetic activation means as is preferred, for example by arranging the magnetically activable switch (e.g. thermal reed switch) in the first housing portion and the magnetic activation means (e.g. at least one of a magnet and a magnetic conductor in combination with a magnet) in the second housing portion.
Alternatively, it may be possible to arrange both a thermal reed switch and a magnet in the first housing portion and provide a magnetic conductor in the second housing portion. Then, the magnetic conductor in the second housing portion serves for conducting the magnetic flux generated by the magnet to the magnetically actuated thermal reed switch.
Preferably, a ferromagnetic material of at least one of the switch and the activation means may be selected such that the predetermined temperature for deactivating the switch is less than the maximum allowed operation temperature of the lighting arrangement. Accordingly, at least one of the switch and the activation means is arranged such that Curie effect of the ferromagnetic material "deactivates" the magnetic effect of at least one of the switch and the activation means which as a result will deactivate the switch (i.e. if the activation means stops being magnetic the switch will be deactivated, or if the switch stops being magnetic the activation means will not influence the switch thus resulting in the switch being deactivated). Possibly, the lighting arrangement may further comprise a heat sink and means for thermally connecting the light source and at least one of the switch and the activation means to the heat sink, thereby allowing for further thermal security control of the lighting arrangement. The predetermined temperature for deactivating the switch may furthermore be defined based on the material of the lighting arrangement or the intended operation conditions of the lighting arrangement. For example, the predetermined temperature may be based on a maximum LED junction temperature, a maximum temperature of e.g. a reflector used with the lighting arrangement, or for making the lighting arrangement safe (e.g. 100°) to be used in combination with textile or wooden materials.
Preferably, the light source comprises at least a light emitting diode (LED). Furthermore, to achieve high energy efficiency the light source may preferably be selected from a group comprising light emitting diodes (LEDs), organic light emitting diodes (OLEDs), polymeric light emitting diodes (PLEDs) and inorganic LEDs. As mentioned above, LEDs have much higher energy efficiency in comparison to conventional light bulbs which generally deliver at best about 6% of their electric power used in the form of light. The skilled person would appreciate that it of course would be possible to use a standard incandescent light source, such as an argon, krypton, and/or xenon light source. In an even more preferred embodiment, the light source may for example comprise a combination of at least some of red, green, blue, yellow, magenta and cyan LEDs for creating mixed color lighting. It is however also possible to use one or a plurality of white LEDs of the same or of different color temperature (e.g. warm white and cold white). Further combinations are of course also possible. Preferably, the interface for connecting the lighting arrangement to the electrical power supply may be selected from a group comprising screw thread interfaces, Bayonet interfaces and pin based interfaces. Additional different interfaces are of course possible. Accordingly, different types of first housing portions having different mains interfaces may be provided for connection to a second housing portion having "standard" (i.e. in relation to the lighting arrangement) electrical connection means adapted for connection with first housing portions having different types of mains interfaces.
For properly securing the two housing portions with each other, the electrical connecting means may comprise mechanical means, including for example at least one of a snap fitting and a press fitting. Also, in a preferred embodiment the electrical connecting means connecting the first and the second housing portions is adapted for allowing distribution of power and control commands. Thereby, the electrical connecting means may be used not only for power distribution but also for control of the light source comprised with the second housing portion. Additionally, the lighting arrangement may comprise control circuitry adapted to receive the control commands and to control the light source. In an embodiment, the control commands may be encoded together with the power provided to the lighting arrangement, e.g. superimposed onto the power. The control commands may thereby be used, by means of the control circuitry for adapting the visible illumination characteristic of the light source, including for example the color emitted by the light source. However, different illumination characteristics may also be changed, such as for example the brightness of the light source as well as a blinking frequency of the light source. It may be possible to use pulse width modulation (PWM) for such control. Also, the control circuitry may be provided with a receiver for receiving control instructions from a remote control and adapted for allowing control of the light source. Additionally, means for actively cooling the light source may be provided.
The lighting arrangement may be provided separately, but may also be provided as a single first housing portion and a plurality of different second housing portions having different lighting characteristics to be individually connected to the first housing portion. Accordingly, the different second housing portions may be "differently magnetically coded" such that they are provided with the correct voltage levels from the first housing portions depending on which electrical path that will be activated by the magnets and the thermal reed switches. Thus, a magnet and a corresponding thermal reed switch together forms a magnetic coding means. According to another aspect of the invention there is provided a first housing portion, comprising an interface for allowing connection to an electrical power supply, electrical connecting means for electrically connecting the first housing portion to a second housing portion having a light source attached thereto, and a magnetically activable switch, wherein in connecting the first housing portion to the second housing portion the switch is activated by magnetic activation means comprised with the second housing portion for providing electrical power from the power supply to the light source, and wherein heat from the light source exceeding a predetermined temperature deactivates the switch. This aspect of the invention provides similar advantages as the first aspect of the invention. In an embodiment, the first housing portion may comprise a plurality of electrical connection means and a plurality of thermal reed switches, thereby allowing for individual connection with a plurality of second housing portions each having individual light source characteristics. Accordingly, different second housing portions having different magnetic coding and/or having different set-ups regarding lighting characteristics (e.g. color, intensity, etc.) may be connected to the first housing portion as is discussed above.
For allowing connection to different types of second housing portions having different lighting characteristics, the first housing portion may furthermore be provided with means for receiving electrical power from the power supply and for distributing power to each of the plurality of electrical connection means having different power levels. Accordingly, different voltage levels may be provided to the second housing portion depending on the positioning and configuration of the magnets and the thermal reed switches.
According to still another aspect of the invention there is provided a second housing portion, comprising a light source, electrical connecting means for electrically connecting the second housing portion to a first housing portion having an interface for allowing connection to an electrical power supply, and magnetic activation means, wherein in connecting the first housing portion to the second housing portion the magnetic activation means activates a magnetically activable switch comprised with the first housing portion for providing electrical power from the power supply to the light source, and wherein the switch is arranged such that heat from the light source exceeding a predetermined temperature deactivates the switch. This aspect of the invention also provides similar advantages as the first and the second aspects of the invention. Additionally, according to this aspect the positioning of the thermal reed switch and the light source in close vicinity may further increase the monitoring of the LEDs.
Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. The skilled addressee realize that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The various aspects of the invention, including its particular features and advantages, will be readily understood from the following detailed description and the accompanying drawings, in which: Fig. 1 illustrates a perspective view of lighting arrangement according to a currently preferred embodiment of the present invention; and
Fig. 2a and 2b illustrates schematic configuration of the different housing portions of the lighting arrangement of Fig. 1.
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 fully convey the scope of the invention to the skilled addressee. Like reference characters refer to like elements throughout.
Referring now to the drawings and to Fig. 1 in particular, there is depicted a lighting arrangement 100 according to a currently preferred embodiment of the present invention. The lighting arrangement 100 comprises a first housing portion 102 and a second housing portion 104.
The first housing portion 102 is in one end formed to have an interface for connecting the lighting arrangement to an electrical power supply, such as in the illustrated embodiment a screw thread 106 adapted to be fitted in a suitable socket (e.g. E 14, E27 or any other similar interface such as e.g. Bayonet). The first housing portion 102 further comprises a plurality of thermal reed switches 108 and a plurality of electrical connecting means in the forms of electrical connection sockets 110. In the illustrated embodiment of Fig. 1, electrical wires internally arranged in the screw thread 106 provides an electric path between the connection points of the screw thread 106 and the thermal reed switches 108. The second housing portion 104 comprises a plurality of LEDs 112 and an optical element 114 (e.g. a dome, a reflector or collimator) for focusing light emitted by the LEDs 112. The LEDs 112 may be of different colors (e.g. different primary colors) and adapted to be individually controlled to emit light of a large number of colors including white light. Also, in correspondence to the electrical connection sockets 110 of the first housing portion 102, the second housing portion 104 comprise electrical connection pins 116 adapted to be fitted into the corresponding electrical connection sockets 110 when connecting the first housing portion 102 to the second housing portion 104. The second housing portion 104 furthermore comprises a plurality of magnets 118 arranged to be aligned with the thermal reed switches 108 of the first housing portion 102 when connecting the first housing portion 102 to the second housing portion 104.
For controlling light emitted from the LEDs 112, at least one of the first and the second housing portions 102, 104 may be provided with a control circuitry (not shown) adapted to receive the control commands and to control the LEDs for adjustably changing the visible illumination characteristic of the LEDs, including for example the color and brightness. The control circuitry may include a microprocessor, microcontroller, programmable digital signal processor or another programmable device. The control circuitry may also, or instead, include an application specific integrated circuit, a programmable gate array or programmable array logic, a programmable logic device, or a digital signal processor. Where the control circuitry includes a programmable device such as the microprocessor, microcontroller or programmable digital signal processor mentioned above, the processor may further include computer executable code that controls operation of the programmable device.
Preferably, the lighting arrangement 100 may be controlled by means of a remote control (not shown) for transmitting control commands to the control circuitry. The control commands may be transmitted by means of RF or light emission, such as for example by means of an infrared transmitter/receiver connected to the remote control and the control circuitry, respectively.
During operation of the lighting arrangement 100, the first housing portion 102 is connected to the second housing portion 104. The electrical connection sockets 110 of the first housing portion 102 makes electrical connection with the corresponding electrical connection pins 116 of the second housing portion 104. However, only when the magnets 118 of the second housing portion 104 are correctly aligned with the thermal reed switches 108 of the first housing portion 102, the thermal reed switches 108 are activated and power will be allowed to flow from the power supply (e.g. mains) through the screw thread 106, the electrical connection sockets 110, the electrical connection pins 116, the control circuits (if present) and to the LEDs 112 which thereby will start to emit light.
However, in case a "wrongly" selected second housing portion is connected to the first housing portion, e.g. where the wrongly selected second housing portion is adapted for a different voltage level due to geographical differences, the positioning of the magnets and the thermal red switches may be "coded" to only correspond to a specific type of first and second housing portions. That is, a specific type of first housing portion may only be used with a specific type of second housing portions due to the individual positioning of the magnetically activable switch and magnetic activation means (e.g. thermal reed switches, magnets and magnet conductors). This gives the different types of housing portions different "magnetic coding" such that wrongly (and e.g. not suitable) connected housing portions will not allow the thermal reed switches to be activated (i.e. due to un-alignment between magnetically activable switches and magnetic activation means) and thus stop power from flowing from the power supply to the LEDs.
Furthermore, by using magnetically activable switches and magnetic activation means for controlling the flow of power to the LEDs 112, it is also possible to deactivate the power provided to the LEDs 112 in case the temperature of the LEDs and/or different sections of the lighting arrangement reach above a predetermined temperature level. For example, by providing the second housing portion with a heat sink (not shown) and thermally connecting both the magnetic activation means and the LEDs to the heat sink, it is possible to adapt the magnetic activation means such that it loses its characteristic ferromagnetic ability, i.e. stops being magnetic and thus stops influence the magnetic switch, which thereby will be deactivated. This effect is caused by the Curie effect. That is, above the Curie point of a ferromagnetic material of the magnetic activation means the ferromagnetic material becomes paramagnetic. Furthermore, the heat sink, the LEDs 112 and the magnets may all be arranged onto a substrate, such as a PCB 120.
Turning now to Fig. 2, illustrating a schematic top view of the first housing portion 102 (Fig. 2a) and a schematic bottom view of the second housing portion 104 (Fig. 2b). In the centre of Fig. 2a it is illustrated the connection points of the screw thread 106 and the electrical wires for electrically connecting the thermal reed switches 108 to the power supply. Furthermore, four thermal reed switches 108 are provided and arranged to control the provision of power to the corresponding four electrical connection sockets 110, forming two pairs of electrical connection sockets 110. As can be seen, each of the electrical connection sockets 110 are individually controlled by means of an individual thermal reed switch 108. In the illustrated embodiment, the two pairs of electrical connection sockets 110 are arranged in parallel, but may of course also be arranged in series depending on the specific implementation. Correspondingly, in Fig. 2b the schematic bottom view of the second housing portion 104 is illustrated, in which the corresponding four electrical connection pins 116, forming two pair of electrical connection pins 116, and magnets 118 are provided. As understood, the positioning of the electrical connection pins 116 and the magnets 118 are such that they align with the four thermal reed switches 108 and the two pairs of electrical connection sockets 110. Thus, when the two pairs of electrical connection pins 116 are arranged in electrical connection with the two pairs of electrical connection sockets 110, and the four reed switches 108 are activated by the four magnets 118, the two LEDs 112, each connected to each one of the pair of electrical connection pins 116, are arranged in parallel and in connection with the electrical interface, e.g. screw thread 106, to the power supply. Different arrangement, positioning and number of the electrical connection sockets 110, the reed switches 108, the magnets 118, the electrical connection pins 116 and the LEDs 112 are of course possible and within the scope of the invention, including for example the possibility to arrange a plurality of lighting arrangements 100 in parallel, such as for example is provided in relation to a decorative lighting system, such as is known in the art, e.g. Christmas lighting having a plurality of light sources arrange in series.
In summary, the present invention relates to a lighting arrangement, comprising a first housing portion and a second housing portion having a light source attached thereto, wherein at least one of the first or the second housing portion comprises a magnetically activable switch and magnetic activation means for activating the switch, respectively, wherein in connecting the first housing portion to the second housing portion the switch is activated for providing electrical power to the light source, and wherein heat from the light source exceeding a predetermined temperature level deactivates the switch.
Advantages with the invention includes interchangeability and automatic configuration between different version of the first and the second housing portions as well as in relation to the possibility to use the Curie effect for temperature protection.
Even though the invention has been described with reference to specific exemplifying embodiments thereof, many different alterations, modifications and the like will become apparent for those skilled in the art. Variations to the disclosed embodiments can be understood and effected by the skilled addressee in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. For example, even though the magnetically activable switch generally has been shown to be comprised in the first housing portion and the activation means has been comprised in the second housing portion, both the magnetically activable switch and the activation means (e.g. a thermal reed switch and a magnet) may be included in the first housing portion. However, in such a case it is desirable to not align the thermal reed switch with the magnet such that the thermal reed switch is always activated, but allow for a magnetic conductor (e.g. an iron bar) comprised with the second housing portion to conduct the magnetism provided by the magnet to activate the thermal reed switch. Consequently, either or both of the magnet and the thermal reed switch may be arranged such that heat from the LEDs makes a ferromagnetic material of either of the magnet and the thermal reed switch to lose its magnetic ability such that the thermal reed switch is deactivated.
Furthermore, in the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.