Energy-efficient lighting system

Abstract

Method for operating a lighting system comprising at least one first and one second light source (3), wherein the light source (3) is supplied with power via an operating device (2) with an external electrical energy source, e.g.the network, is connectable, in which additional electrical energy is obtained from the light of the light source (3) not used for lighting purposes or from natural and / or artificial ambient light by photovoltaic energy conversion and supplied to the operating device for utilization, characterized in that the at least one first and one second light source (3) are operated in a "master / slave" relationship, such that the additional energy generated for the second light source (3) is at least partially generated from the light of the first light source (3), in which the first light source (3) is also connected to its external energy source (mains) in the inactive state - accepting standby losses - for the purpose of receiving start-up energy, and in which the second light source (3) is completely disconnected from its external energy source (mains) in the inactive state.

Description

The light sources used in lighting installations, for example gas discharge lamps or LEDs, are supplied with the appropriate operating voltage or appropriate operating current via operating devices. The operating devices generate the operating voltage or the current from the alternating current grid or from a direct voltage source. In order to be able to switch the light sources on or off and dim separately, the individual operating devices can be controlled from a control center via a bus. Each operating device often contains at least one control IC which, in addition to the control, is also responsible for communication with the central station and with external sensors, etc. Active semiconductor ICs operate at a low voltage of a few volts. This low-voltage voltage is taken from frequently clocked assemblies during steady-state operation. Before these clocked modules carry out their operation correctly, a so-called "starting voltage" must be present, which enables, for example, the starting up of the control IC in the operating device, so that the latter can then control, for example, the clocked modules. In order to always keep a starting voltage ready for the control ICs, the operating devices in bus-controlled lighting systems remain connected to the AC power supply system even in the inactive state, i.e. when the light sources to be supplied by them are switched off (when the starting energy is obtained, for example, via a so-called starting resistor), with the result that corresponding standby losses are produced.CN 1971125 A describes a lighting device with a switched-mode power supply with the possibility of mains operation or solar operation.CN 200965187 Y describes a lighting system in which LED lights can be operated via a controller by means of solar power or by means of mains power.CN 101173747 A describes an integrated light system which can be supplied with energy in mains operation or in solar operation.The object of the invention is to specify a method for improving the energy efficiency of a lighting system of the type described above, which has at least one first and one second light source, and a lighting system of corresponding design.The solution for the method is the subject matter of independent claim 1, and the solution for the lighting system is characterized by the combination of features of independent claim 10.The central idea of the two solutions is to convert the unused light of the light sources or of natural and / or artificial ambient light (sun, other artificial light sources,... ) photovoltaically into electrical energy and to utilize this as additional energy for operating the light sources. This idea is gaining importance if the light sources are supplied with operating voltage by operational devices capable of busing. The photovoltaically generated additional electrical energy can namely be used to obtain the starting voltage necessary for a control IC, so that at least a part of the latter can be disconnected from the mains by a plurality of operating devices of the lighting system when they are placed in the inactive state via the bus.The term "light of the light sources not used (for illumination purposes)" is to be understood as meaning that portion of the light emitted by the light source which, for example, is not used for illumination purposes because of its emission direction, and would otherwise be absorbed, for example, by components of the luminaire and would therefore represent power loss.Thus, in each case at least two light sources can be operated in a "master / slave" ratio such that the additional energy generated for the second light source originates at least partially from the first light source.Although the first light source remains connected to the external energy source (network) in the inactive state-assuming standby losses-for the purpose of absorbing starting energy, the second light source can then be completely disconnected from its external energy source in the inactive state.At least one photovoltaic element can be used for the recovery of the additional energy. If the light source is equipped with a reflector, the at least one photovoltaic element is expediently arranged at a location of the reflector where the photovoltaic element is best irradiated with direct or indirect one of its own light source or other light sources or ambient light. For optimum irradiation of the photovoltaic element with external light or with ambient light, the outer side of the reflector is particularly suitable.It has been found that the efficiency curve of photovoltaic elements matches well with the spectrum of the light emitted by gas discharge lamps. However, the use of LEDs as light sources has also proven to be advantageous because their spectrum can be adapted to the efficiency curve of photovoltaic elements by selecting and combining differently colored LEDs. In this respect, a light source suitable for the purpose provided here can be, for example, an LED or a combination of LEDs of different colors or a gas discharge lamp.The additional energy obtained by photovoltaic energy conversion can be stored in a memory. A simple capacitor is suitable for this purpose, among other things.A photovoltaic element used for energy conversion can assume still further functions in lighting installations of the type under consideration here, such as, for example, as an ambient light sensor, as a motion detector, as a control element for dimming the associated light source, and as an actual value sensor in a control loop for regulating the overall brightness composed of the light emitted by the light source and the ambient light.An important separate aspect of the invention is furthermore that a common low-voltage energy store is provided for a plurality of light sources or for their operating devices of a lighting installation. The energy obtained by photovoltaic energy conversion is stored therein. In addition, external energy can be fed in by a connection to an external energy source (network). All operating devices should also be able to operate without the external energy source (network). The operating energy within each operating device is to be taken only from the common low-voltage energy store.The features of the claims are intended to be fully incorporated into the disclosure of the description in order to avoid unnecessary repetitions.An exemplary embodiment of the invention is described below with reference to the single figure.The single FIGURE shows a schematic section through a luminaire with a gas discharge lamp (fluorescent tube) as light source and the assemblies of interest here of the associated operating device.The luminaire 1 consists of an operating device 2 which supplies an electric operating energy to a light source 3 in the form of a fluorescent tube. However, the invention also relates to operating devices, for example for halogen lamps, white or colored LEDs or OLEDs, etc.Two reflectors 4a, 4b are located on the luminaire 1. Photovoltaic elements 5 a, 5 bare arranged on the upper side of the reflectors, which are connected to the operating device 2 via electrical plug connections 6 a, 6 b.In the example shown, the luminaire 1 belongs to a lighting system with a plurality of such luminaires, which are not shown, however. All lamps can be controlled via a common bus and supplied with external energy from a common mains line.The operating device 2 contains an electronic switch 7, via which the operating device 2 can be connected to the network line.The operating device 2 further contains a lamp voltage generator which generates a high-frequency high voltage for the light source 3 from the mains voltage. The lamp voltage generator 8 can be activated or deactivated by a control IC 9 contained in the operating device 2 and optionally dimmed. The respective control commands are supplied to the control ICs from an external center through the bus.In order that the at least one control IC 9 can react immediately upon the arrival of a control command, they require a low-voltage voltage as starting energy, which they are obtained from a low-voltage generator 10. This generates the starting voltage normally from the mains voltage. For this purpose, it must be permanently connected to the network. This in turn results in corresponding standby losses having to be accepted.In order to avoid the latter, the low-voltage generator draws its energy, as far as possible, from two photovoltaic storage units 11 a, 11 b, which in turn are connected to the photovoltaic elements 5 b, 5 bvia the electrical plug connections 6 a, 6 b. The photovoltaic storage devices 11 a, 11 bare capacitors, for example, but other energy storage devices such as rechargeable batteries can also be used. The photovoltaic elements 5 a, 5 bconvert light impinging thereon into additional electrical energy for the operating device 2 or the light source 3. This is reflected, i.e. indirect, light of the light source 3, direct or indirect light of the adjacent light sources or ambient light. Instead of the light source 3, however, other light sources such as LEDs can also be used.When the photovoltaic elements 5a, 5b are irradiated with light, the low voltage generator 10 can be disconnected from the mains by means of the switch 7 when the lamp voltage generator 8 is switched inactive from the central station via the bus. Then, when the command to re-activate the lamp voltage generator 8 comes, the control ICs can start up immediately because the low voltage generator 10 is supplied with auxiliary power from the photovoltaic memories 11 a, 11 b. This may require that the photovoltaic elements 5 a, 5 bare irradiated with light at the time of arrival of the turn-on command. If photovoltaic storage devices 11 a, 11 bare used which can maintain the stored energy over a longer time, the energy stored by the photovoltaic storage devices 11 a, 11 bmay also be used directly for providing the starting energy at the time of the arrival of the switch-on command, without light irradiation on the photovoltaic elements 5 a, 5 bbeing required at this moment.The energy generated by the photovoltaic elements 5 a, 5 bor the energy stored by the photovoltaic storages 11 a, 11 bmay also be used for feeding the light source 3, i.e. for feeding the lamp voltage generator 8, for example. In this case, the light source can also be supplied by mixed supply operation by means of supply from the grid and from the energy of the photovoltaic elements 5 a, 5 b. The energy stored in the photovoltaic memory 11 a, 11 bmay also be used for supplying the light source 3, for example, in a time-controlled manner or as a function of information, for example a control command received from the outside, or information about the mains supply, such as, for example, energy costs information.However, the energy stored in the photovoltaic storage 11 a, 11 bmay also be used for emergency lighting in the event of a mains voltage failure, for example, in which, in the event of such a mains voltage failure, the energy stored in the photovoltaic storage 11 a, 11 bis used for operating a connected light source (for example by supplying the lamp voltage generator 8). The possibilities mentioned for using an at least partial supply of the light source by the photovoltaic elements 5 a, 5 bor also the use for emergency lighting can be advantageous, for example, in the case of an LED lighting system.According to the invention, two lights of a lighting system formed by a plurality of lights are operated in a master / slave relationship. For this purpose, one of the two lamps is permanently connected to the mains, while the other lamp is disconnected from the mains by the switch 7 if the two lamps are jointly switched inactive via the bus. When the command to activate the lamp voltage generators 8 is then fed back to the two lamps via the bus, the light source 3 of the "master" lamp lights up immediately, the low-voltage generator 10 of this lamp drawing its energy from the mains. The slave lamp is activated correctly-despite the corresponding command-only when the light of the master lamp falls onto the photovoltaic elements 5 a, 5 bof the slave lamp, so that the corresponding starting energy is then available for the control ICs 9 in the operating device 2 of the slave lamp. Then the control ICs 9 of the slave light can close the switch 7 again, with the result that the lamp voltage generator 8 starts and supplies the light source 3 with operating energy.In the case of the version described above, the photovoltaic elements 5 a, 5 bcan be removed in the "master" luminaire, which is very simple because of the plug connections 6 a, 6 b. In the case of the slave luminaire, on the other hand, the switch 7 and the connection between the low-voltage generator 10 and the network are permanently unnecessary. However, if a luminaire as described in connection with the single figure has all the elements shown, the luminaire can be used and programmed in any combination with others. The top goal is to minimize or even completely avoid standby losses.The photovoltaic elements 5 a, 5 bmay also additionally assume other functions, for example as an ambient light sensor, as a motion detector, as a control element for dimming the associated light source and as an actual value sensor in a control circuit for regulating the overall brightness composed of the light emitted by the light source and the ambient light.In a lighting system with several lights of the type described in connection with the single FIGURE, it is also possible to assign a common low-voltage energy store to all lights or their operating devices, which can cover the requirements of all operating devices. If the common energy store still requires additional energy, it can receive it from the grid.

Claims

Method for operating a lighting system having at least one first and one second light source (3), wherein the light source (3) can be connected to an external electrical energy source, e.g. the network, for the purpose of supplying power via an operating device (2), in which additional electrical energy is obtained from the light of the light source (3) not used for lighting purposes or from natural and / or artificial ambient light by photovoltaic energy conversion and is supplied to the operating device for utilization, characterized in that the at least one first and one second light source (3) are operated in a "master / slave" ratio such that the additional energy generated for the second light source (3) is generated at least partially from the light of the first light source (3), in which the first light source (3) is connected to its external energy source (grid) for the purpose of absorbing starting energy even in the inactive state-with the acceptance of standby losses-and in which the second light source (3) is completely disconnected from its external energy source (grid) in the inactive state.Method according to Claim 1, in which the additional energy obtained by energy conversion serves to generate a low-voltage supply voltage, which is preferably used as starting energy for at least one active, i.e. voltage-supplied, semiconductor IC (9).Method according to claim 1 or 2, wherein one or more photovoltaic element / s (5a, 5b) is used for generating the additional energy.Method according to one of Claims 1 to 3, in which a fluorescent lamp (3), an LED and / or the combination of a plurality of LEDs of different colour is used as the light source.Method according to one of Claims 3 to 4, in which the additional energy generated by the photovoltaic element (5a, 5b) is stored in an energy store (11a, 11b), for example a capacitor, which then provides the low-voltage supply voltage.Method according to Claim 5, in which a common energy store (11a, 11b) is used for a plurality of light sources (3) or operating devices (2).Method according to one of Claims 3 to 6, in which the photovoltaic element / s (5a, 5b) is also used as an ambient light sensor or motion detector.Method according to one of Claims 3 to 7, in which the brightness of the light source (3) which can be varied by dimming is controlled by the photovoltaic element / s (5a, 5b) as a function of the ambient light.Method according to one of Claims 3 to 8, in which the photovoltaic element / s (5a, 5b) is also used as an actual value sensor for the total brightness composed of the ambient light and the light emitted by the light source (3), in which the actual value of the total brightness determined by the photovoltaic element / s (5a, 5b) is compared with a setpoint value and a control difference is determined, and in which the control difference is used in a control loop as a control value for setting a dimming value for the light source (3).Lighting arrangement comprising: - at least one light source (3), - an operating device (2) for the at least one light source (3), which can be connected to an external energy source, e.g. the grid, and supplies the at least one light source (3) with operating energy, - means (10, 11a, 11b) for generating and storing a low-voltage supply voltage for at least one active, i.e. voltage-supplied semiconductor IC (8) of the operating device, and - means (5a, 5b) for photovoltaically converting the light emitted directly or indirectly by the light source (3) or an adjacent light source (3) and / or the ambient light into additional electrical energy, wherein the additional energy is supplied to the means (10) for generating and providing a low-voltage supply voltage, characterized in that, the at least one first and one second light source (3) are operated in a "master / slave" ratio such that the additional energy generated for the second light source (3) is generated at least partially from the light of the first light source (3), wherein the first light source (3) is also connected to its external energy source (grid) in the inactive state-with the acceptance of standby losses-for the purpose of absorbing starting energy, and wherein the second light source (3) is completely disconnected from its external energy source (grid) in the inactive state.Lighting arrangement according to claim 10, having means for activating or deactivating the operating device (2), and having switch means (7) for connecting or disconnecting the operating device (2) to or from the external energy source (network), wherein the connecting or disconnecting means (7) can be controlled by the semiconductor IC (8) of the operating device (2), namely in such a way that the operating device (2) is also disconnected from the external energy source (network) in the event of deactivation, and furthermore in such a way that the operating device (2) is also connected to the external energy source (network) in the event of activation, provided that additional electrical energy is available for the semiconductor IC (8) of the operating device (2), and wherein the connection between the operating device and the external energy source (network) is permanently maintained, if additional energy is not continuously available for the semiconductor IC (8) of the operating device (2).Lighting arrangement according to claim 10 or 11, wherein the means (11a, 11b) for storing a low voltage supply voltage are formed by a capacitor.Lighting arrangement according to one of Claims 10 to 12, wherein the means for photovoltaic energy conversion are formed by at least one photovoltaic element (5a, 5b).Lighting arrangement according to claim 13, wherein the at least one light source (3) is surrounded by a reflector (4a, 4b), and wherein the at least one photovoltaic element (5a, 5b) is arranged on the outside of the reflector (4a, 4b).Lighting arrangement according to one of claims 10 to 14, wherein the light source (3) is formed by a gas discharge lamp, by an LED or a combination of a plurality of differently coloured LEDs.Lighting arrangement according to one of Claims 10 to 15, wherein a common energy store (11a, 11b) is provided for a plurality of light sources (3).Lighting arrangement according to any of claims 13 to 16, wherein the at least one photovoltaic element (5a, 5b) is also used as an ambient light sensor or motion detector.Lighting arrangement according to one of claims 13 to 16, wherein the brightness of the light source (3) that can be varied by dimming is controlled by the at least one photovoltaic element (5a, 5b) as a function of the ambient light.Lighting arrangement according to one of Claims 13 to 16, wherein the at least one photovoltaic element (5a, 5b) is also used as an actual value sensor for the total brightness composed of the ambient light and the light emitted by the light source (3), wherein the actual value of the total brightness determined by the at least one photovoltaic element (5a, 5b) is compared with a setpoint value and a control difference is determined, and wherein the control difference is used in a control loop as a control value for setting a dimming value for the light source (3).

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