WO2014140961A1

WO2014140961A1 - A lighting device and luminaire comprising an antenna.

Info

Publication number: WO2014140961A1
Application number: PCT/IB2014/058964
Authority: WO
Inventors: Lihua LIN; Xiaodong GE; Jianping Zhang; Shan Wang
Original assignee: Koninklijke Philips N.V.
Priority date: 2013-03-13
Filing date: 2014-02-13
Publication date: 2014-09-18

Abstract

The invention provides a lighting device (100) and a luminaire. The lighting device comprises alight emitter (102) thermally connected to a heat sink (104). The lighting device further comprises an antenna (110) configured for being connected to a communication circuit and configured for transmitting and/or receiving a communication signal. The antenna is at least partially enclosed by the heat sink. The antenna may, for example, be arranged inside a recess (130). The recess may have an opening (140) arranged for transmitting and/or receiving the communication signal. In an embodiment, the opening is equal to or larger than 1/8 of the wavelength of the communication signal.

Description

A lighting device and luminaire comprising an antenna

Field of the invention

The invention relates to lighting device comprising an antenna. The invention further relates to a luminaire comprising the lighting device.

Background of the invention

Tele-management of light sources both for indoor and outdoor applications are increasingly popular. Intelligent lighting has become widespread, and RF communication is a powerful technology to be used in this tele-management of lamps, in particular for domestic and office environments. Instead of controlling the power supply to the lamp, the trend has moved towards directly controlling the light source or lighting device (for example an exchangeable element of the lamp) by sending an RF control signal to the lighting device.

One example of such light source comprising a luminescent material can be found in the published patent application US2010/140136A1 which relates to a lighting device such as a replacement lighting device, comprising a light source (e.g. LED) for producing light. The lighting device further comprises a heat sink made of a material with an electrical resistivity being less than 0.01 Qm (e.g. a metallic heat sink) which is part of the housing and transports heat away from the light source. A radio frequency communication circuit connected to an antenna serves to enable RF signal communication (e.g. to control the device via a remote control). The antenna is arranged at least 2 mm outside the heat sink.

A problem of this lighting device is that the required arrangement of the antenna limits the applicable light power of the known lighting device.

Summary of the invention

It is an object of the invention to provide a lighting device having RF communication in which the light emission power may be increased.

A first aspect of the invention provides a lighting device. A second aspect of the invention provides a luminaire. Advantageous embodiments are defined in the dependent claims.

A lighting device in accordance with the first aspect of the invention comprises a light emitter thermally connected to a heat sink. The lighting device further comprises an antenna configured for being connected to a communication circuit and configured for transmitting and/or receiving a communication signal. The antenna is at least partially enclosed by the heat sink. Due to this arrangement of the antenna in the lighting device according to the invention, the volume of the heat sink may be further increased without increasing the outer dimensions of the lighting device, thus enabling to increase the efficiency of the heat dissipation to the environment which enables an increase in the light emission power of the lighting device while still being able to transmit and/or receive the communication signal.

A trend in current industry is that lighting devices are becoming smaller and smaller. Because generally, the light emitters generate a significant amount of heat, cooling of the light emitter is a crucial problem which has to be solved to further miniaturize the lighting devices, while maintaining or even increasing the light emission power of these lighting devices. Especially when the light emitter is a semiconductor light emitter, such as a Light Emitting Diode (further also indicated as LED) or an Organic Light Emitting Diode (further also indicated as OLED), the outer dimensions may be decreased significantly, and may substantially only be limited by the required volume of the heat sink to ensure sufficient heat dissipation from the semiconductor light emitter. In the known lighting device, the antenna is arranged outside the heat sink to ensure good communication between the antenna and the communication signal. However, this requirement will reduce the possible dimensions of the heat sink and thus will limit the light emission power of the known lighting device. The inventors have found that the antenna may be at least partially enclosed by the heat sink to ensure good emission and/or receiving of the communication signal. This enables the lighting device according to the invention to increase the volume of the heat sink and as such allow further increase of the light emission power in the lighting device while maintaining good communication.

Lighting devices according to the invention are often enclosed by some kind of housing, for example, in a luminaire. Such a housing limits the flow of air passing the heat sink and thus limits the heat flow from the heat sink to the environment. An important flow of heat from the heat sink to the environment in the housing is immediately at a light- emission opening of the housing from which the light is emitted by the lighting device. In the known lighting device the heat sink is arranged at least 2 mm away from the extending antenna, thus located away from the light-emission opening of the housing, which strongly reduces any heat flow from the heat sink to the environment via the light-emission opening. In the lighting device according to the invention the antenna is at least partially enclosed by the heat sink, enabling the heat sink to extend up to the light-emission opening of the housing and as such enabling heat flow from the heat sink via the light-emission opening into the environment. This further improves the efficiency of the heat sink in the lighting device according to the invention.

In an embodiment of the lighting device according to the invention, the heat sink comprising a recess and the antenna is arranged inside the recess. Such recess may be part of the cooling structure of the heat sink or may be any other recess in the heat sink. To ensure a good transmission and/or receiving of the communication signal, the recess may, for example, be open towards the light-emission opening of the housing as indicated before.

In the lighting device according to the invention, the recess comprises an opening for transmitting and/or receiving the communication signal from the heat sink, the opening having a dimension equal to or larger than 1/8 of the wavelength of the

communication signal. In such an arrangement, the opening in the recess is large enough for the communication signal to reach the antenna and provide relatively good signal quality. When the opening of the recess is directed towards the light-emission opening of the housing, this light-emission opening of the housing should, of course, also be equal to or larger than 1/8 of the wavelength of the communication signal.

In the lighting device according to the invention, a rim of the opening in the recess defines an imaginary plane, the antenna being arranged inside the recess at a side of the imaginary plane facing the recess. This embodiment allows the lighting device to be compact, as the antenna is arranged inside the recess, below the imaginary plane. This imaginary plane may, for example, comprise a non-conductive shielding to shield the antenna from sight without obstructing the communication signal to reach the antenna. This non- conductive shielding may also be used to protect the antenna from dirt or other environmental influences.

In an embodiment of the lighting device, a distance between the imaginary plane and the antenna is smaller than the wavelength of the communication signal. The inventors have found that there is still communication possible when the opening in the recess has a diameter of at least 1/8 of the wavelength of the communication signal and when the distance between the imaginary plane and the antenna is less than the wavelength of the communication signal. Of course, typically, when the distance between the antenna and the imaginary plane is smaller, the signal strength received by the antenna and/or the signal strength emitted by the antenna is improved.

In an embodiment of the lighting device, the light emitter is arranged inside the recess, and the recess constitutes at least a part of a collimator for collimating light of the light emitter. In such an embodiment, the surface of the recess may, for example, be coated with a reflecting layer for efficiently reflecting and collimating light from the light emitter via the opening away from the lighting device. Alternatively, the surface of the recess may, for example, be coated with a color conversion material for changing a color of at least a part of the light emitted by the light emitter into light having a different color. In such an

embodiment, the additional color conversion material may be used to define a color of the overall light emitted by the lighting device. The imaginary surface defined by the opening in the recess may comprise, for example, the non-conductive shielding being a light emission window via which light is emitted away from the lighting device. This light emission window may, for example be a diffuse light emission window to diffuse the light emitted by the LEDs or OLEDs. In an alternative embodiment this light emission window may also comprise color conversion material to define a color of the light emitted by the lighting device. The antenna is arranged inside the recess hidden away behind the light emission window, and protected from dirt or other environmental influences.

In an embodiment of the lighting device, the antenna is arranged inside the recess at a distance away from a wall of the recess. Because the recess is part of the heat sink, the wall of the recess may, for example, comprise conductive materials which would limit or block the communication signal.

Optionally, the antenna is arranged on printed circuit board at least partially arranged inside the recess. Such a printed circuit board may comprise connection wires between the antenna and the communication circuit such that the received communication signal may be provided to the communication circuit from the antenna, or that the

communication signal to be transmitted may be provided to the antenna from the

communication circuit.

In an embodiment of the lighting device, the printed circuit board further comprises driver electronics for providing a driving signal to the light emitter. The driving signal may, for example, provide power to the light emitter to ensure the light emitter emits light. Alternatively, the driving signal may be used to dim or otherwise control the emission of light from the light emitter. In a preferred embodiment, the driving signal may, for example, dim the light emitter by providing a pulse width modulated drive signal (further also indicated as PWM drive signal) in which the width of the pulse in the drive signal determines an emitted intensity by the light emitter.

Optionally, the recess further comprises cooling fins. Especially in an embodiment in which the opening in the recess is not blocked by a non-conductive shielding or by a light emission window, these additional cooling fins may further increase the cooling of the light emitter and as such enable a further increase of light power to be included in the lighting device.

Optionally, the recess is configured for reflecting the communication signal to and/or from the antenna.

Optionally, the lighting device further comprises a control circuit for controlling the lighting device in response to the received communication signal. The control circuit may, for example, be configured for controlling a functioning of the lighting device, wherein the functioning of the lighting device is selected from a list comprising: on- switching, off- switching, dimming, changing color, timing the on-switching, timing the off- switching, changing focus of the emitted light, controlling beam angle, estimating life-time, consumption of power, detecting failure, and identification.

In an embodiment of the lighting device, the lighting device comprises an outer shape arranged to cooperate with light-mounting constructions selected from the list comprising: E27, E14, E40, B22, GU-10, GZ10, G4, GY6.35, G8.5, BA15d, B 15, G53, PAR, and GU5.3.

The luminaire according to the second aspect comprises the light source according to the invention.

These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.

It will be appreciated by those skilled in the art that two or more of the above- mentioned options, implementations, and/or aspects of the invention may be combined in any way deemed useful.

Modifications and variations of the color conversion arrangement, the lighting unit and the solid state light emitter package, which correspond to the described

modifications and variations of the color conversion arrangement, can be carried out by a person skilled in the art on the basis of the present description.

Brief description of the drawings

In the drawings:

Figure 1 shows a schematic plan- view of the lighting device according to the invention, Figure 2 shows a schematic plan- view of the same lighting device in which a non-conductive cover is arranged over the light emitters,

Figure 3 shows a schematic exploded view of the lighting device according to the invention,

Figure 4 shows a schematic cross-sectional view of the lighting device according to the invention,

Figure 5 shows another schematic cross-sectional view of the lighting device according to the invention, and

Figure 6 shows a schematic plan- view of the lighting device according to the invention in which the outer shape of the lighting device is arranged to cooperate with light mounting constructions, and

Figure 7 shows a schematic embodiment of a luminaire according to the invention. It should be noted that items denoted by the same reference numerals in different Figures have the same structural features and the same functions, or are the same signals. Where the function and/or structure of such an item have been explained, there is no necessity for repeated explanation thereof in the detailed description.

The Figures are purely diagrammatic and not drawn to scale. Particularly for clarity, some dimensions are exaggerated strongly.

Detailed description

Figure 1 shows a schematic plan- view of the lighting device 100 according to the invention. The lighting device 100 comprises a light emitter 102 thermally connected to a heat sink 104. The lighting device 100 comprises a Printed Circuit Board 170 (further also indicated as PCB), which partially extends into the recess 130 and which comprises an antenna 110 configured for being connected to a communication circuit 172 (see Fig. 3), for example, via connection wires of the PCB 170. The light emitter 102 is arranged on a further PCB 180 (see Fig. 3) which is attached to a rear wall 160 of a recess 130. The recess 130 has an opening 140 via which the light of the light emitter 102 is emitted away from the lighting device 100. The recess 130 has a further opening 106 (see Fig. 3) via which the PCB 170 extends into the recess 130. The recess 130 as shown in Figure 1 also comprises cooling fins 135 which increase the heat dissipating capacity of the heat sink 104. Figure 2 shows a schematic plan- view of the same lighting device 100 in which a non-conductive cover 190 is arranged to cover the light emitters 102 (not visible in Figure 2) and over the antenna 110 (also not visible in Figure 2). Further indicted in Figure 2 is the heat sink 104 and additional cooling fins 135. This non-conductive cover 190 may, for example, be used to reduce any environmental influences to the light emitters 102 and/or to the antenna 110. Alternatively, the non-conductive cover 190 may be a light emission window 190 which may, for example be a diffuse window 190 for diffusing the light emitted by the light emitters 102, or which may be a lens or part of a lens to refract the light emitted by the light emitters 102 (Figure 1). In an embodiment of the lighting device 100, the light emission window 190 may also comprise color conversion materials (not shown) such as luminescent materials. These color conversion materials typically absorb part of the light emitted by the light emitters 102 and convert and re-emit the absorbed light into light of a different color for controlling an overall color of the light emitted by the lighting device 100. Applying these color conversion materials at the light exit window 190 has some advantages in that a temperature of the color conversion materials is limited which improves the life time of these color conversion materials (remote phosphor arrangement). In an alternative embodiment, the color conversion materials may, for example, be directly applied on a surface of the light emitter 102 or even on a wall 160 of the recess 130.

Color conversion materials may comprise organic luminescent materials or phosphors and inorganic luminescent materials or phosphors. The inorganic luminescent material may, for example, comprises a yellow or yellow/green emitting inorganic phosphor, such as YAG and/or LuAG, or a red inorganic phosphor such as ECAS and/or BSSN.

Particles of inorganic luminescent materials may, for example, be dispersed in a matrix polymer or may also be dispersed in Silicone or other epoxies and/or resins. In other embodiments, an inorganic phosphor forms the basis of a ceramic luminescent layer. Organic luminescent materials or phosphors have a high quantum efficiency and are often transparent, which prevents undesired scattering and increases efficiency. Organic luminescent materials have more advantages. The position and the bandwidth of the luminescence spectrum can be designed with ease to be anywhere in the visible range. As such it is relatively easy to manufacture a light source which emits white light with high efficacy. Also molecules of organic luminescent materials or phosphors may be dissolved in a matrix polymer, or in Silicone, or in epoxies or resins. A combination of different luminescent materials may be used to improve a color rendering index (CRI) of the light emitted by the color conversion arrangements. Multilayer stacks of luminescent materials may be used or different luminescent materials may be mixed in a single layer.

The non-conductive cover 190 is configured for substantially freely transmitting the communication signal through the non-conductive cover 190. In the non- conductive cover 190 shown in Figure 2 an embossment 195 is applied which indicates that there is an antenna 110 inside the recess 130.

Figure 3 shows a schematic exploded view of the lighting device 100 according to the invention. This exploded view again shows the non-conductive cover 190 together with the embossment 195, and shows connection means 10, 12, for example some screws 12 and bolts 10 for assembling the lighting device 100. Next the further PCB 180 is shown which comprises the light emitters 102. Also in this further PCB 180 a further opening 182 is present to allow the PCB 170 to at least partially extend into the recess 130. The further PCB 180 is connected to a rear wall 160 of the recess 130. Typically some heat conductive means (not shown) are applied between the further PCB 180 and the rear wall 160 of the recess 130 to ensure good thermal connection between the light emitters 102 and the heat sink 104. A next element of the lighting device 100 shown in Figure 3 is the heat sink 104 comprising the recess 130. The recess 130 comprises the opening 140 via which the communication signal is received or transmitted, and via which the light is emitted from the light emitters 102. The rear wall 160 of the recess 130 has a further opening 106 via which the PCB 170 can extend into the recess 130. The heat sink 104 again has additional cooling fins 135 to further increase the surface of the heat sink 104 to improve the exchange of heat from the heat sink 104 towards the environment. The PCB 170 also comprises the antenna 110 which - in this embodiment of the lighting device 100) is arranged on an extension 171 of the PCB 170 which fits through the further opening 106 of the rear wall 160 of the recess 130 and through the further opening 182 of the further PCB 180 such that the antenna 110 extends into the recess 130. The PCB 170 further comprises a connector 178 for connecting the PCB 170 via another opening (not shown) in the rear wall 160 of the recess 130 to the further PCB 180. The PCB 170 as shown in Figure 3 also comprises driver electronics 174 for providing a driving signal to the light emitters 102, for example, via the connector 178. The PCB 170, for example, also comprises a control circuit 176 for controlling the lighting device 100 in response to the received communication signal, and comprises a

communication circuit 172 which is connected to the antenna 110 via connection wires (not shown). Finally, the PCB 170 comprises connectors 179 for connecting the PCB 170 to a power supply, such as the mains power supply (not shown). To ensure that the outer shape of the lighting device 100 can cooperate with some predefined mounting construction (in the current case the GU5.3 standard housing), and for enforcing the assembled lighting device 100 according to the invention, the exploded view of Figure 3 shows a locking element 20.

Figure 4 shows a schematic cross-sectional view of the lighting device 100 according to the invention. Again, the cross-sectional view shows the heat sink 104 having the recess 130 which extends into the heat sink 104 via the further opening 106. The cross- sectional view also shows the light emitter 102 arranged underneath the non-conductive shielding 190 and a schematic outline of the PCB 170 having connectors 179 for connection to a power supply (not shown). In Figure 4 also an imaginary plane 150 is indicated which is defined by a rim 142 of the opening 140 in the recess 130. A distance d indicates where the antenna 110 (not shown) may be located within the recess 130, depending on the dimensions of the opening 140 and the further opening 106. As indicated before, when the opening 140 and the further opening 106 is at least 1/8 of the wavelength of the communication signal, the dashed polygon in Figure 4 shows possible locations where the antenna 110 (not shown) may still be located to enable communication. In such an embodiment, the distance d to the imaginary plane 150 should not exceed the wavelength of the communication signal. Of course positioning the antenna 110 (not shown) relatively close to the imaginary plane 150 would ensure good communication quality between the lighting device 100 and its environment.

The antenna 110 (not shown) and the communication circuit 172 (see Fig. 3) may be configured to communicate with the environment via a wireless RF control signal, for example, in a frequency range between 1 and 3 Giga Hertz, for example, using the ZigBee, BlueTooth or Wi-Fi standard at or around a frequency of 2.4 Giga Hertz. Of course also other frequency ranges may be used for this communication without departing from the scope of the invention.

Figure 5 shows another schematic cross-sectional view of the lighting device 100 according to the invention. The cross-section of Figure 5 is rather similar to the cross- section of Figure 4, apart from the fact that the arrangement shown in Figure 5 comprises a single light emitter 102 arranged in the center of the recess 130 and comprising a collimator 108 or beam shaping element 108 for shaping or redirecting the light emitted by the light emitter 102. This collimator 108 or beam shaping element 108 may also comprise color conversion materials for converting at least a part of the light emitted by the light emitter 102 into light of a different color. Also indicated in Figure 5 are the heat sink 104, a schematic outline of the PCB 170 and connectors 179 for connecting to a power supply (not shown). In this arrangement, again two dashed polygons are indicated, showing possible alternative locations of the antenna 110 (not shown) as long as there is an opening to outside the heat sink 104 which has a dimension of at least 1/8 of the wavelength of the communication signal and in which a distance d between the imaginary plane 150 and the antenna 110 (not shown) does not exceed the wavelength of the communication signal. And again, positioning the antenna 110 (not shown) relatively close to the imaginary plane 150 would ensure good communication quality between the lighting device 100 and its environment.

Figure 6 shows a schematic plan- view of the lighting device 200 according to the invention in which the outer shape of the lighting device 200 is arranged to cooperate with a similar light mounting construction - again GU5.3. The lighting device 200 again has a heat sink 204, comprising a recess 230 and a light emission window 270 similar to the light emission window 190 shown in Figures 2, 3 and 4. This different embodiment of the lighting device 200, the light emitter (not shown) is connected to the heat sink 204. The lighting device 200 further comprises an antenna (not shown) at least partially enclosed by the heat sink 204 and arranged at a side of the light emission window 270 facing the light emitter.

Figure 7 shows a schematic embodiment of a luminaire 300 according to the invention. The luminaire 300 comprises, for example, light mounting constructions which can cooperate with the outer dimensions of the lighting device 100, 200 such that the lighting device 100, 200 may be fit into the luminaire 300.

Summarized, the current application provides a lighting device 100, 200 and a luminaire 300. The lighting device 100, 200 comprises a light emitter 102 thermally connected to a heat sink 104, 204. The lighting device 100, 200 further comprises an antenna 110 configured for being connected to a communication circuit 172 and configured for transmitting and/or receiving a communication signal. The antenna 110 is at least partially enclosed by the heat sink 104, 204. The antenna 110 may, for example, be arranged inside a recess 130. The recess 130 may have an opening 140 arranged for transmitting and/or receiving the communication signal, in which the opening 140 is equal to or larger than 1/8 of the wavelength of the communication signal.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CLAIMS:

1. A lighting device (100, 200) comprising a light emitter (102) thermally connected to a heat sink (104, 204), the lighting device (100, 200) further comprising an antenna (110) configured for being connected to a communication circuit (172) and configured for transmitting and/or receiving a communication signal, wherein the antenna (110) is at least partially enclosed by the heat sink (104, 204).

2. The lighting device (100, 200) according to claim 1, the heat sink (104, 204) comprising a recess (130, 230), wherein the antenna (110) is arranged inside the recess (130, 230).

3. The lighting device (100, 200) according to claim 2, wherein the recess (130, 230) comprises an opening (140) for transmitting and/or receiving the communication signal from the heat sink (104, 204), the opening (140) having a dimension equal to or larger than 1/8 of the wavelength of the communication signal.

4. The lighting device (100, 200) according to claim 3, wherein a rim (142) of the opening (140) defines an imaginary plane (150), the antenna (110) being arranged inside the recess (130, 230) at a side of the imaginary plane (150) facing the recess (130, 230).

5. The lighting device (100, 200) according to claim 4, wherein a distance (d) between the imaginary plane (150) and the antenna (110) is smaller than the wavelength of the communication signal.

6. The lighting device (100, 200) according to claim 2, the light emitter (102) being arranged inside the recess (130, 230), wherein the recess (130, 230) comprises at least a part of a collimator (108) for collimating light of the light emitter (102).

7. The lighting device (100, 200) according to claim 2, wherein the antenna (110) is arranged inside the recess (130, 230) at a distance away from a wall (160) of the recess (130, 230).

8. The lighting device (100, 200) according to claim 2, wherein the antenna (110) is arranged on printed circuit board (170) at least partially arranged inside the recess (130, 230).

9. The lighting device (100, 200) according to claim 8, wherein the printed circuit board (170) further comprises driver electronics (174) for providing a driving signal to the light emitter (102).

10. The lighting device (100, 200) according to claim 2, wherein the recess (130, 230) further comprises cooling fins (135).

11. The lighting device (100, 200) according to claim 2, wherein the recess (130, 230) is configured for reflecting the communication signal to and/or from the antenna (110).

12 The lighting device (100, 200) according to claim 1, wherein the lighting device (100, 200) further comprises a control circuit (176) for controlling the lighting device (100, 200) in response to the received communication signal.

13. The lighting device (100, 200) according to claim 12, wherein the control circuit (174) is configured for controlling a functioning of the lighting device (100, 200), the functioning of the lighting device (100, 200) being selected from a list comprising: on- switching, off- switching, dimming, changing color, timing the on-switching, timing the off- switching, changing focus of the emitted light, controlling beam angle, estimating life-time, consumption of power, detecting failure, and identification.

14. The lighting device (100, 200) according to any of the previous claims, wherein the lighting device (100, 200) comprises an outer shape arranged to cooperate with light-mounting constructions selected from the list comprising: E27, E14, E40, B22, GU-10, GZ10, G4, GY6.35, G8.5, BA15d, B 15, G53, PAR, and GU5.3.

15. A luminaire (300) comprising the lighting device (100, 200) according to any of the previous claims.