Lighting system and method for determining water ingress into a luminaire

Abstract

The invention relates to a lighting system (100) comprising a lighting unit (101), a housing (102) containing at least a part of the lighting unit, wherein the lighting unit and the housing are part of a luminaire, and a sensing device (103) positioned at or inside the housing, wherein the sensing device is adapted to sense a functional parameter indicative of a functional property of the luminaire affected by water ingress into at least a part of the luminaire. Further, the lighting system comprises a water ingress determination unit (104) adapted to determine water ingress into at least a part of the luminaire based on the sensed functional parameter. Thus, a lighting system is provided which allows to determine water ingress into the luminaire before the water can damage the luminaire, thereby improving the durability and safety of the luminaire.

Description

Technical Field

[0001] This invention relates to lighting systems, as well as methods and computer programs for determining the amount of water entering a lighting unit. Background Technology

[0002] Water ingress into lighting fixtures is a common malfunction, continuing to rank near the top of annual incidents. Water ingress often leads to corrosion, condensation on transparent parts (such as the window of the lighting fixture), or even catastrophic on-site product failure, both of which occur with outdoor and indoor lighting fixtures.

[0003] In associated lighting systems comprising multiple illuminators, there is an unmet need for monitoring each individual illuminator for potential water condensation and / or water ingress. Therefore, low-cost sensor hardware is required to implement this water ingress sensing functionality. A sensing function is also needed to predict whether water ingress will only lead to condensation or even result in puddles. Puddles can cause product failure, which may even be critical to safety. At the other extreme of severity, condensation typically occurs first on lenses and reflectors, and only reduces the illuminator's ability to properly illuminate the environment and / or affects its aesthetic appearance. Therefore, it is desirable to accurately and easily measure water ingress in each individual illuminator to overcome these problems.

[0004] US2017 / 184659A1 discloses a luminaire including at least one luminaire component. The luminaire may further include at least one sensor that measures at least one parameter associated with the at least one luminaire component. The luminaire may also include a prognostic and health monitoring (PHM) system coupled to the at least one sensor, wherein the PHM system analyzes at least one measurement performed by the at least one sensor to identify at least one factor affecting the lifespan of the at least one luminaire component.

[0005] US 2011 / 304268A1 discloses a lighting device that may include at least one semiconductor light source, at least one sensor, and evaluation electronics functionally connected to the at least one sensor, wherein the evaluation electronics is arranged to trigger at least one action of the lighting device based on at least one predetermined sensor signal of the at least one sensor. Summary of the Invention

[0006] The object of this invention is to provide a lighting system, method, and computer program product that takes into account the improved durability and safety of the luminaire.

[0007] In a first aspect, a lighting system is provided, wherein the system comprises: a) a lighting unit adapted to provide light; b) a housing containing at least a portion of the lighting unit, wherein the lighting unit and the housing are part of a luminaire; c) a sensing device located at or within the housing, the sensing device being adapted to sense functional parameters indicating functional characteristics of the luminaire affected by water entering at least a portion of the internal structure of the luminaire; and d) a water entry determining unit adapted to determine water ingress into at least a portion of the internal structure of the luminaire based on the sensed functional parameters.

[0008] Because the water ingress detection unit is adapted to determine water ingress into at least a portion of the illuminator's internal structure based on sensed functional parameters indicating the illuminator's functional characteristics affected by the water ingress, water ingress can be detected indirectly based on the water's influence within the illuminator. This avoids the structurally challenging direct measurement of the water's influence within the illuminator. Furthermore, small amounts of water, which are typically difficult to measure with ordinary water or humidity sensors, can affect the illuminator's functional characteristics (e.g., pressure within the illuminator's housing), thus allowing for the detection of water presence before actual damage to the illuminator (e.g., anticipated corrosion). This allows for improved illuminator durability and safety.

[0009] The illuminator includes at least one illumination unit. The illumination unit is adapted to provide light. Specifically, the illumination unit is adapted to provide light comprising electromagnetic radiation having wavelengths within a predetermined range of the electromagnetic spectrum. In particular, the light may comprise electromagnetic radiation having different discrete or continuous wavelength ranges within the predetermined range of the electromagnetic spectrum. Preferably, the illumination unit is adapted to provide at least visible light. Thus, visible light is defined by a wavelength range sensitive to the human eye, i.e., wavelengths can be in the range of 380 nm to 780 nm. The illumination unit may be adapted to provide white light comprising radiation having wavelengths within the hundreds of nanometers range of visible light, wherein the spectrum may be continuous or discrete. However, the illumination unit may also be adapted to provide colored light comprising radiation with wavelengths within the tens of nanometers range of visible light; for example, green light primarily comprises radiation with wavelengths in the range of 500 nm to 550 nm. The illumination unit may also be adapted to provide light of any other color. Additionally or alternatively, the illumination unit may be adapted to provide light comprising electromagnetic radiation having wavelengths insensitive to the human eye. For example, the light provided may be sterilizing light, which includes radiation from the electromagnetic spectrum that includes ultraviolet radiation. The light provided may also include radiation from the electromagnetic spectrum that includes infrared radiation.

[0010] An illumination unit suitable for providing light can be any light source that emits electromagnetic radiation with a continuous or discrete wavelength spectrum. For example, an illumination unit can be a light-emitting diode (LED). However, the illumination unit may also include other light-providing devices, such as VCSELs, incandescent lamps, halogen lamps, fluorescent lamps, metal halide lamps, gas discharge lamps, etc. The illumination unit may also include any combination of light sources. In this case, the light provided by the illumination unit is the sum of the light provided by each light source in the illumination unit.

[0011] The lighting unit is adapted to be at least partially surrounded by a housing. The housing is adapted to surround at least a portion of the lighting unit. In particular, the housing may also be adapted to surround the entire lighting unit. Preferably, the housing is configured such that it can protect at least a portion of the lighting unit against external conditions such as weather conditions. Circuitry and electronic components for controlling and operating the lighting unit may be part of the housing and thus connected to the lighting unit, or may be part of the lighting unit itself. The housing may then at least partially surround these circuitry and electronic components.

[0012] The housing may be closed or may have openings. The openings may be adapted to allow, for example, cables or fasteners to enter the housing for connection to the housing or lighting unit. In this case, the openings may be sealed, for example, by providing additional cable seals, thereby protecting the interior of the housing. Preferably, all openings of the housing are sealed to prevent water from entering the housing.

[0013] The housing can be made of a single material. Thus, the housing can be made of glass, transparent plastic, acrylic glass, or any other transparent material, allowing the light provided by the lighting unit to be positioned outside the housing. The housing can also be constructed from a combination of at least two materials. Preferably, the housing is adapted to protect its internal volume against external conditions (e.g., weather conditions) and to provide light outward from the internal volume through the housing. The internal volume of the housing may include at least a portion of the internal structure of the illuminator. In this case, the volume of the housing can be divided by the internal structure. Typically, the sensing device is adapted to sense functional parameters within the housing. Additionally or alternatively, the sensing device may also be adapted to sense functional parameters, for example, in a portion of the housing defined by the internal structure of the housing.

[0014] A lighting unit and its housing can be considered to form a luminaire. A luminaire can be located inside or outside a building. Multiple luminaires can be arranged together to perform a task, such as illumination or guidance. Typically, one or more luminaires can be provided in any known manner.

[0015] The lighting system, particularly the illuminator, also includes at least one sensing device. The sensing device may be located at the housing of the illuminator, i.e., in functional contact with the housing of the illuminator. For example, the sensing device may be attached to the exterior of the housing. Alternatively, the sensing device may be located inside the housing. For example, the sensing device may be positioned somewhere within the volume surrounded by the housing, without directly contacting the housing itself.

[0016] The sensing device is adapted to sense functional parameters indicating the functional characteristics of an illuminator. Generally, a functional characteristic refers to a characteristic of the illuminator that is functionally related to its function (e.g., the process of providing light). For example, during the process of providing light, the temperature and / or pressure within the housing can be affected, and therefore the temperature and / or pressure within the housing can be considered functionally related to the illuminator's illumination function. Furthermore, a functional parameter measured by the sensing device refers to a functional characteristic affected by water entering at least a portion of the illuminator's internal structure, where the internal structure of the illuminator can be considered the volume contained within the housing. For example, the temperature or pressure within the housing may be affected by water entering at least a portion of the illuminator's internal structure, and in this case, it can indicate a functional characteristic; thus, the sensing device can be adapted to measure a functional parameter indicating the functional characteristic. Additionally, other characteristics can also be used as functional characteristics. For example, in some cases, the conductivity and / or resistance of a portion of the illuminator may also be affected by water entering at least a portion of the illuminator's internal structure, and therefore can be considered a functional characteristic of the illuminator. In some cases, the sensing device can be adapted to directly sense the functional characteristic as a functional parameter. However, in other embodiments, the functional parameter is merely an indication of the functional characteristic, i.e., it has a known functional relationship with the functional characteristic.

[0017] The lighting system includes a water ingress determination unit. The water ingress determination unit is adapted to determine water ingress into at least a portion of the internal structure of the luminaire based on sensed functional parameters. The water ingress determination unit can be implemented as hardware or software on a general-purpose or special-purpose computing system. Typically, the water ingress determination unit is adapted to receive signals indicating the sensed functional parameters from a sensing device, for example, via a wired or wireless connection to a sensing device.

[0018] In one embodiment, the water ingress detection unit can be integrated into the illuminator. In this case, the water ingress detection unit can be inside or outside the housing of the illuminator. However, the water ingress detection unit can also be provided separately from the illuminator, but it can be connected to the illuminator's sensing device via wired or wireless communication. For example, the water ingress detection unit can be part of a separate device, such as software running on a user device (e.g., a smartphone), or it can be part of an overall control system that controls more than one sensing device, or controls multiple different sensors, devices, lighting units, and / or illuminators.

[0019] The water ingress determination unit can be adapted to determine the ingress of water into at least a portion of the internal structure of the illuminator based on the functional parameters sensed by the sensing device. Specifically, the water ingress determination unit can be adapted to utilize a functional relationship between the amount of water and / or water vapor present in the internal structure of the illuminator and the functional parameters. Such a functional relationship can be stored as part of the water ingress determination unit or provided to the water ingress determination unit from external memory. Typically, such a functional relationship can be provided as a mathematical relation, a set of rules, a lookup table, etc. The functional relationship between the ingress of water into the internal structure of the illuminator and at least one functional parameter can be determined, for example, by experimenting with the illuminator or by computationally modeling the illuminator, applying known physical laws and knowledge about the construction of the illuminator. For example, the functional relationship can be determined experimentally by measuring at least one functional characteristic (such as temperature or pressure) within the housing of the illuminator, which depends on the amount of water supplied to the internal structure of the illuminator. Based on such measurements, known statistical analysis tools can be applied to determine the functional relationship. Furthermore, machine learning techniques can also be applied. For example, measurement results can be used as training data to feed machine learning algorithms (such as neural networks, Bayesian networks, etc.) so that the algorithm can be trained to determine the amount of water in the illuminator based on functional parameters. The use of machine learning algorithms is particularly advantageous when multiple functional parameters (specifically, functional parameter profiles) are provided by the sensing device, because if trained accordingly, machine learning algorithms can even evaluate complex relationships between different parameters.

[0020] The result of determining water ingress can then be provided to the user, for example, in the form of visual or auditory output. For example, when ingress is determined to be potentially harmful to the illuminator or to potentially reduce its functionality (e.g., light emission), the lighting unit can be adapted to provide specific light, such as light of a specific color. Additionally or alternatively, the result can also be provided, for example, on a display of a user interface communicating with at least the water ingress determining unit, as a visualization of the determined water content, such as by providing a value indicating the amount of water determined to be present in the internal structure of the illuminator. Additionally or alternatively, the result of determining water ingress can also be visualized indirectly, for example, by providing the level of damage (expected to originate from the determined ingress). Furthermore, based on this result, additionally or alternatively, recommendations can be provided to the user (e.g., a recommendation to change the illuminator) to turn off the power to the illuminator or contact service personnel. Alternatively, the lighting system can be adapted to react automatically to the result of determining water ingress. For example, rules can be stored in the lighting system that control the function of the illuminator based on the result of determining water ingress (e.g., based on the amount of water determined in the internal structure of the illuminator). In one example, the lighting system may be adapted to control the lighting unit to increase or decrease the intensity of the light provided and / or to control the spectrum provided by the lighting unit based on the determined amount of water ingress. If it is determined that the amount of water present in the illuminator may have fatal consequences, the lighting system may be adapted to control the illuminator to be shut off. This avoids any risk of circuit failure or short circuit.

[0021] In one embodiment, the water ingress determination unit is adapted to determine water ingress into at least a portion of the internal structure of the luminaire by comparing a sensed functional parameter with a predetermined reference to that parameter. The functional parameter may indicate one or more measured values ​​for that parameter. Furthermore, the functional parameter may also indicate the evolution of the parameter's value over time. The reference to the functional parameter may then correspondingly refer to one or more values ​​or to the evolution of the functional parameter. Typically, the reference indicates the functional parameter under specific known conditions. For example, the reference may indicate the measurement of the functional parameter in the absence of water in the internal structure of the luminaire, in the presence of a specific amount of water in the internal structure of the luminaire, during a specific time of day, during specific environmental conditions, etc. Preferably, the reference is determined during measurements of the functional parameter at the manufacturer's location with predetermined settings, where in this case, the same reference can be provided to all luminaires with the same construction, i.e., a reference luminaire model can be used. However, a reference can also be established at the customer's location after the luminaire is installed, for example, by measuring the functional parameter at some point shortly after installation, with the expectation that the newly installed luminaire will not have a significant amount of water ingress.

[0022] Typically, a comparison of a functional parameter with a reference can refer to any type of comparison between two values ​​or functions. For example, as a comparison, the difference or ratio between the functional parameter and the reference can be determined. However, if the functional parameter and the reference refer to values ​​evolving over time (i.e., functions), the comparison can also refer to comparing the waveform of the function. For example, the comparison can be related to a specific data point of the function, its maximum or minimum value, gradient, etc. The water ingress determination unit can then be adapted to determine the ingress of water into at least a portion of the internal structure of the illuminator based on the shape (i.e., waveform) of the sensed functional parameter function or the result of a comparison of a specific data point with a predetermined reference function of the parameter. For example, the functional relationship between the comparison result and the ingress of water into the internal structure of the illuminator can be predetermined. Such a functional relationship, for example, associates one or more comparison results with a specific amount of water within the internal structure of the illuminator. However, a simple functional relationship that only provides qualitative information about whether ingress has been detected can also be used. For example, when the comparison provides a result that the measured functional parameter differs from the reference, the water ingress determination unit can be adapted to determine that ingress has occurred. However, the water ingress determination unit can also be adapted to apply more complex functional relationships, where the comparison result is again compared with, for example, one or more thresholds to determine the amount of water present in the luminaire. Such thresholds can be determined, for example, through experiments or simulations related to functional parameters. For instance, if the functional characteristic of the luminaire refers to its internal pressure, and it is known that if the internal pressure value affected by water ingress increases by 20% compared to a reference internal pressure determined by the manufacturer, then water ingress damages a portion of the luminaire. Thus, the threshold could refer to a 20% deviation from the reference.

[0023] The predetermined reference for the parameter can be a stored value, which can be a sensed value or a calculated value sensed by a sensing device. The water ingress determination unit is adapted to receive the predetermined reference for the parameter from a storage unit storing the predetermined reference. If the predetermined reference for the parameter is stored at a storage unit, the storage unit can be located at the water ingress determination unit or at any other separate device or cloud. If the storage unit storing the predetermined reference for the parameter is not located at the water ingress determination unit, then the water ingress determination unit can be connected to the device storing the predetermined reference for the parameter. For example, the predetermined reference for the parameter can be a series of values ​​measured at different times of day. Thus, the water ingress determination unit can be adapted to determine water ingress into at least a portion of the internal structure of the illuminator by comparing the sensed functional parameter with a stored predetermined reference for the parameter at the same time of day.

[0024] In a preferred embodiment, the benchmark for the functional parameters is predetermined based on a parameter model adapted to model the functional parameters of the lighting unit in response to the surrounding environmental conditions and / or operating state and / or water ingress state of the lighting unit.

[0025] The operating state of a luminaire can refer to any state of the luminaire related to its operation. For example, the operating state of a lighting unit can be either the on or off state. In the on state, the lighting unit provides light, while in the off state, it does not provide light. The operating state of a lighting unit can also refer to any dimming state of the lighting unit, where dimming refers to the state in which light with a predetermined light intensity is provided. The on state of the lighting unit can also be understood as a dimming state. The operating state can also be a complete sleep state or a download state of the luminaire. For example, if an external signal is received or not received within a predetermined time period, a complete sleep state can be provided by the lighting unit being in the off state. In a complete sleep state, one or more functions of the lighting unit can be limited; for example, the provided lighting can refer only to emergency lighting, and network capabilities or communication functions can be limited to receiving wake-up signals, etc. The advantage of this complete sleep state is reduced power consumption of the lighting unit. The download state of the lighting unit can refer to the state in which the lighting unit receives (i.e., downloads) information, data, software updates, etc., preferably, the operating state of the lighting unit is on, off, or dimming. The water entry state can be any state of the luminaire regarding water entry. For example, "water entering state" can refer to the amount of water present in a luminaire.

[0026] The parametric model can be any model suitable for modeling functional parameters based on ambient conditions and / or water ingress and / or operational status. Preferably, the model is adapted to model the evolution of the values ​​of the functional parameters over time. Exemplarily, where the functional characteristic refers to temperature, the model can be understood as a temperature model adapted to simulate the temperature at the sensing device location within at least a portion of the internal structure of the luminaire's housing based on ambient conditions and / or water ingress and / or operational status, for example, based on the amount of water within the internal structure of the luminaire's housing and whether the luminaire is in an on or off state. Furthermore, the model can be adapted to additionally consider other parameters, preferably the luminaire's structural characteristics. Typically, the parametric model can be provided based on known physical relationships between different physical quantities affecting the functional parameters of the luminaire. For example, the ideal gas law, heat transfer equations, etc., can be used to provide the mathematical background for the parametric model.

[0027] In one embodiment, the sensing device is adapted to sense the functional parameters of the luminaire under different operating states of the lighting unit, and the water ingress determination unit is adapted to determine water ingress into at least a portion of the internal structure of the luminaire based on a comparison of the functional parameters determined under the different operating states of the lighting unit. For example, the sensing device may be adapted to sense a first functional parameter during the off state of the luminaire and a second functional parameter during the on state of the luminaire. The water ingress determination unit may then be adapted to determine water ingress based on a comparison of the first and second functional parameters determined for the two different operating states. Typically, water ingress into the luminaire can have different effects on the functional parameters of the luminaire under different operating states. For example, water ingress can affect the pressure difference or temperature difference between the different operating states of the luminaire. Therefore, the water ingress determination unit can provide and utilize functional relationships to deduce the water ingress situation from a comparison of the functional parameters sensed under the different operating states of the luminaire.

[0028] In an embodiment, a functional parameter indicates the pressure within at least a portion of the illuminator's housing. To sense the pressure, a sensing device is adapted to sense at least one functional parameter indicating the pressure within at least a portion of the housing. Preferably, the sensing device is adapted to directly sense the pressure within the illuminator's housing. For example, the sensing device may be positioned within the housing to sense the pressure. In this embodiment, the sensing device may refer to a piezoresistive strain gauge sensor, a capacitive pressure sensor, a piezoelectric pressure sensor, etc. Typically, the presence of water, particularly water in the form of water vapor, has an effect on the illuminator's pressure response, for example, altering environmental conditions or operating states.

[0029] In a preferred embodiment, the sensing device is positioned at the housing of the illuminator and adapted to sense deformation of at least a portion of the housing as a functional parameter, the functional parameter indicating pressure within at least a portion of the housing of the illuminator. For example, the functional characteristic of the illuminator may be the length, area, or volume of a portion of the housing indicating pressure within at least a portion of the housing. In particular, changes in the length, area, or volume of at least a portion of the housing may indicate changes in pressure within at least a portion of the housing. In a preferred embodiment, the sensing device includes at least a strain gauge sensor positioned at the housing or as a portion of the housing of the illuminator and adapted to sense deformation of the portion of the housing as a functional parameter, the functional parameter indicating pressure within at least a portion of the housing of the illuminator. In particular, the strain gauge may be adapted to monitor deformation of the illuminator housing due to a pressure differential outside the housing. Alternatively, the sensing device may also include at least one MEMS pressure sensor or piezoresistive sensor or any other sensor sensitive to deformation of at least a portion of the housing. Preferably, the sensing device is adapted to provide a pressure distribution as a functional parameter, wherein the pressure distribution refers to a series of values ​​measured over time indicating pressure within the housing. In one embodiment, the pressure distribution measured during a day (e.g., exactly one day after the installation of the lighting fixture) can be used as a predetermined baseline, and all subsequent pressure distributions are compared to this predetermined baseline to determine the water inlet conditions.

[0030] In a preferred embodiment, the housing includes at least a flexible portion and a rigid portion, wherein the flexible portion is more flexible than the rigid portion, and wherein the sensing device is adapted to sense the deformation of the housing by sensing the deformation of the flexible portion of the housing. Because in this embodiment, the housing includes at least a flexible portion and a rigid portion, wherein the flexible portion is more flexible than the rigid portion, the deformation of the flexible portion of the housing due to pressure differences with the environment will be more pronounced. This allows for more accurate measurement of the housing deformation, thereby providing more accurate functional parameters. For example, a more flexible portion of the housing can be achieved by providing a flexible portion with a different material than the rigid portion, by providing a flexible portion with a reduced thickness compared to the rigid portion, or by providing a flexible portion with another structure (e.g., having multiple grooves, etc.). In a preferred embodiment, the sensing device includes a copper track positioned on the surface of the flexible portion, the copper track being adapted to function as a strain gauge sensor.

[0031] In one embodiment, the sensing device is adapted to sense a mechanical force applied to at least a portion of the housing as a functional parameter, the functional parameter indicating the pressure within at least a portion of the housing of the illuminator. For example, the sensing device may be a piezoresistor to sense the mechanical force applied to at least a portion of the housing. Because the mechanical force can originate from pressure changes within at least a portion of the housing compared to pressure outside the housing of the illuminator, if the mechanical force affects the piezoresistor, the piezoresistor passively generates a voltage dependent on the mechanical force.

[0032] In a preferred embodiment, the housing includes a rubber ring as a flexible portion. The rubber ring is adapted to seal the illuminator to prevent water ingress. For example, if the housing consists of two parts, the rubber ring can be positioned between the two parts and adapted to seal the internal structure of the housing to prevent water ingress. The sensing device is preferably at least one piezoresistive device adapted to sense the mechanical force applied to the rubber ring by, for example, the pressure difference between the inside and outside of the housing of the illuminator, and the sensing device can be positioned in direct contact with the rubber ring. In a preferred embodiment, the housing includes at least two parts, wherein the pressure difference between the inside and outside of the housing of the illuminator causes pressure to press at least two parts of the housing against each other. In this embodiment, it is preferred that a sensing device is provided such that the pressure between the at least two parts can be measured as an indication of the pressure within the housing. For example, if the at least two parts include a rubber ring therebetween, the piezoresistive device can be positioned below the rubber ring, i.e., between one of the two parts of the housing and the rubber ring.

[0033] In an embodiment, the sensing device is adapted to sense a parameter indicating the temperature of the illuminator as a functional parameter. The temperature of the illuminator can be measured within at least a portion of the illuminator's housing by means of a temperature sensing device within the housing. Preferably, the temperature of the illuminator is measured within the housing, and the internal temperature value can be compared with a previous measurement of the internal temperature or a predetermined temperature reference. Furthermore, the water ingress determination unit can be adapted to receive information about the external temperature of the illuminator, and the water ingress determination unit can be adapted to further determine the ingress water based on the external temperature (e.g., based on a comparison of the external temperature and the internal temperature).

[0034] In an embodiment, the functional parameter indicating the temperature of the illuminator refers to the temperature distribution measured during a change in the operating state of the illuminator from one operating state to another. The temperature distribution includes a series of temperature values ​​within at least a portion of the illuminator's housing, wherein the temperature values ​​are preferably measured continuously over a time period that includes the transition between two different operating states of the illuminator. As described above, an operating state can refer to the on or off state of the illuminator, or any dimming state of the illuminator. The operating state can also refer to the state of the illuminator, i.e., two on states or two off states of the illuminator, for example, where the operating state of the illuminator can be a fully sleep state compared to a download state. A change in operating state can refer to a change from any operating state of the illuminator to any other operating state of the illuminator. For example, the temperature distribution can be measured during a change from one dimming state to another dimming state or from one dimming state to an off state. Therefore, the development of temperature (i.e., the temperature distribution) during the change from one operating state to another can indicate the entry of water into the internal structure of the illuminator. For example, water entering a luminaire can alter the luminaire's thermal inertia, i.e., its responsiveness to temperature changes due to changes in operating conditions. The water entry determination unit can then be adapted to determine this change in thermal inertia based on a temperature distribution, for example, by comparing a currently measured temperature distribution with a previously measured temperature distribution, or by determining characteristics of the temperature distribution (such as gradient, maximum, minimum, etc.) and applying a predetermined functional relationship. Preferably, the water entry determination unit is adapted to determine water entry into at least a portion of the luminaire's internal structure by comparing a sensed temperature distribution with a predetermined reference to the temperature distribution, wherein the predetermined reference to the distribution is sensed by the temperature sensing device when no water is present in the luminaire's internal structure. Additionally or alternatively, the water entry determination unit is adapted to use a temperature model to predict the temperature distribution of the luminaire under different water entry states. Thus, the water entry determination unit is adapted to determine water entry by comparing this temperature distribution with at least one temperature distribution generated by the temperature model (e.g., by determining the deviation between the sensed temperature distribution and the temperature distribution generated by the temperature model).

[0035] In a preferred embodiment, the lighting system further includes a functional parameter providing unit adapted to provide functional parameters regarding another illuminator that is part of the lighting system or located outside the lighting system. The water ingress determining unit is adapted to receive the provided functional parameters and further determine, based on the provided functional parameters, the water ingress into at least a portion of the internal structure of the illuminator. The functional parameter providing unit is adapted to provide functional parameters for another illuminator (preferably a plurality of other illuminators), wherein the water ingress determining unit is adapted to determine, based on multiple provided functional parameters of the other illuminator or the plurality of other illuminators, the water ingress into at least a portion of the internal structure of the illuminator. The other illuminator or the plurality of other illuminators may be part of the lighting system or may be outside the lighting system, for example, part of another lighting system.

[0036] The function parameter providing unit can be a receiving unit for receiving function parameters provided by other illuminators or multiple other illuminators. Additionally or alternatively, the function parameter providing unit can also be a storage unit that stores the function parameters provided by other illuminators (preferably multiple other illuminators); for example, the function parameter providing unit can be provided in the form of cloud storage. Additionally or alternatively, the water entry determining unit can be adapted to receive the function parameters provided by other illuminators (preferably multiple illuminators), such that the water entry determining unit can then be considered as the function parameter providing unit. The function parameter providing unit can, for example, be provided within the housing of the illuminator as a structural part of the illuminator, or it can be structurally separated from the illuminator to, for example, be part of a computing system that communicates with the sensing device of the illuminator and / or the water entry determining unit.

[0037] In a preferred embodiment, the water ingress determination unit for the illuminator is adapted to further determine water ingress into at least a portion of the internal structure of the illuminator based on functional parameters provided by other illuminators (e.g., by applying an anomaly detection algorithm). Preferably, the water ingress determination unit is adapted to determine water ingress into at least a portion of the internal structure of one of the illuminators by comparing the functional parameters (e.g., temperature distribution) from the illuminator with functional parameters provided by the at least one other illuminator or the plurality of illuminators. Typically, it is contemplated that only a very small portion of the plurality of illuminators will be affected by water ingress, allowing other illuminators to provide a good basis for determining water ingress by monitoring changes between different illuminators. Furthermore, the functional characteristics of the illuminator are affected by external conditions, such as weather conditions. Such conditions are largely the same for all illuminators in a particular area, allowing differences in functional parameters compared to a baseline determined in a laboratory that is caused by external conditions rather than water ingress to be identified, which can be identified when comparing the functional parameters of the plurality of illuminators. Therefore, such differences caused by external conditions can be taken into account when water ingress is determined and thus can be determined more accurately. Preferably, if multiple functional parameters of other illuminators are provided, the water ingress determination unit is adapted to select from multiple provided functional parameters of other illuminators subjected to the same environmental conditions, based on monitoring of the functional parameters, information about the relative position of the illuminators, and / or environmental information. For example, the water ingress determination unit may be adapted to determine, based on the ambient temperature information of each illuminator, that one group of illuminators is mostly located in a shaded area, while another group of illuminators is exposed to strong sunlight for part of the day. The water ingress determination unit may then be adapted to determine water ingress into the internal structure of the illuminator by comparing the functional parameters of the illuminator with the functional parameters of one or more illuminators belonging to the same group of illuminators.

[0038] In a preferred embodiment, the illuminator includes a sensing device adapted to sense more than one functional parameter. Specifically, the sensing device may be adapted to sense: a pressure parameter within at least a portion of the indicator housing as a first functional parameter; and a temperature parameter within the same portion of the illuminator housing as a second functional parameter. The relationship between the pressure parameter within at least a portion of the internal structure of the indicator illuminator and the temperature parameter within at least the same portion of the internal structure of the indicator illuminator can be empirically calculated using the ideal gas law PV = nRT, where P is pressure, V is volume, n is amount of substance, R is the ideal gas constant, and T is temperature. Thus, the water ingress determination unit may be adapted to determine water ingress into at least a portion of the internal structure of the illuminator housing based on the relationship between pressure P and temperature T. Preferably, the water ingress determination unit is adapted to determine water ingress by comparing this relationship with a value determined based on the ideal gas law for the case of no water ingress into the internal structure of the illuminator housing. In another preferred variant, the ideal gas law may also be used to monitor the relationship between pressure and temperature distributions for the operating state of the illuminator unit, wherein water ingress is determined based on the deviation of the sensed pressure and temperature distributions from determined reference pressure and temperature distributions for the operating state of the illuminator unit.

[0039] In one embodiment, another sensing device is provided, adapted to sense a humidity parameter within at least a portion of the housing of an indicator illuminator, wherein a water ingress determination unit is adapted to further determine water ingress into at least a portion of the internal structure of the illuminator based on the humidity parameter. The humidity parameter can indicate the humidity within at least a portion of the housing, i.e., the amount of water in the air present within that portion of the housing. However, the humidity parameter can also indicate the amount of water present in at least a portion of the housing but not in the air within the housing, i.e., water that has condensed. Specifically, the humidity parameter indicates either absolute humidity or relative humidity within at least a portion of the housing. Absolute humidity H A The relationship between relative humidity (HR) and total humidity (H) can be derived from the August-Roche-Magnus equation and the ideal gas law, and is further supported by H. A =cH R / T describes the temperature, where T is the temperature and c includes physical constants and parameters that are constant within the enclosure. Within the sealed enclosure, absolute humidity is constant, therefore relative humidity varies with temperature.

[0040] In one embodiment, absolute humidity can be calculated using the following formula:

[0041]

[0042] Here, Po is the partial vapor pressure at infinity, H is the enthalpy of vaporization of water, and R is the gas constant. H is the mass of a water molecule, and T is the temperature, where HA and H R Given as a percentage. Specifically, to calculate absolute humidity, the following value can be used: P0 = 1.002 × 10⁻⁶ 11 N / m 2 , H=42809J / mol, R=8.3345J / (K·mol), The water ingress determination unit can be adapted to use this relationship to determine whether the housing is still sealed, i.e., the relationship is still satisfied, or whether water ingress has occurred to the point that the relationship is no longer satisfied. Preferably, the sensing device further includes a temperature sensing device, and the water ingress determination unit is adapted to monitor the temperature distribution and humidity distribution sensed by the temperature sensing device and a further humidity sensing device, respectively, for the operating state of the lighting unit. For the operating state of the lighting unit, the water ingress determination unit can then be adapted to determine the ingress of water into at least a portion of the internal structure of the luminaire based on the temperature distribution combined with the humidity distribution. In particular, water ingress into at least a portion of the housing of the luminaire increases the thermal mass of the luminaire, causing the temperature response within the housing (i.e., the temperature change within the housing due to changes in the temperature outside the housing) to be delayed. In one embodiment, the temperature and humidity distributions within the housing are monitored over a certain time range, wherein the temperature and humidity distributions have a specific shape within a specific time range, which is attributed, for example, to the position of the sun heating the luminaire. In a closed housing, the relationship between the temperature and humidity distributions can be described as defined by the above relationship, which can be used as a model. Therefore, by comparing the model of the relationship between temperature and humidity distributions within a specific time range with the currently measured temperature and humidity, the water entry determination unit can determine water entry.

[0043] In one embodiment, the housing includes a countersink, configured such that water present in the housing will accumulate in the countersink, wherein additional sensing devices are adapted to sense the presence of water in the countersink. For example, the countersink can be understood as a cavity that opens at the top and closes at the bottom, the cavity including a volume for collecting water that has entered at least a portion of the housing. Specifically, the housing, including walls having inner and outer surfaces, is shaped such that a large amount of water condensed in at least a portion of the housing can, for example, reach the countersink, the water moving, for example, by gravity acting on the condensate. For example, water can enter at least a portion of the housing as liquid water or as gaseous water, wherein in the case of gaseous water, water molecules are distributed in the air that can enter the housing. In this case, water can condense on the inner surface of the housing and be pulled downwards by gravity along the direction of the countersink, causing water to accumulate at the inner surface of the housing wall and / or in the countersink. Preferably, the countersink includes the deepest point of the housing relative to the ground, such that water can reach the countersink solely by gravity.

[0044] The additional sensing device can be any sensing device capable of sensing the functional characteristics of the volume contained in the countersink, affected by the presence of water in the countersink. For example, the additional sensing device may include electrodes connected to electronic circuitry and positioned at the countersink, such that the conductivity and / or resistance of the volume contained in the countersink, as a functional characteristic, can be monitored, and the conductivity and / or resistance of the volume contained in the countersink is affected by the presence of water in the countersink. Preferably, the functional parameter indicating the functional characteristic can be resistance or capacitance sensed by the electrodes and electronic circuitry. The functional parameter can also be any other electrical quantity related to the functional characteristics of the volume contained in and affected by water in the countersink. The water ingress determination unit is then adapted to further determine the water ingress into at least a portion of the internal structure of the luminaire based on the results of a measurement of humidity (in this case, water) in the countersink. For example, the amount of water measured in the countersink can be compared with the amount of water determined from other functional parameters to determine the reliability of the water ingress determination or to increase the accuracy of the water ingress determination.

[0045] As an addition to or alternative to the countersunk hole, the housing may include a moisture-retaining substrate, wherein the additional sensing device is adapted to sense humidity parameters by sensing electrical parameters of the moisture-retaining substrate. The moisture-retaining substrate can be any substrate suitable for absorbing moisture (i.e., water) from the environment. In a preferred embodiment, the moisture-retaining substrate comprises salt or a conductive plastic polymer. The moisture-retaining substrate is positioned within at least a portion of the housing. The additional sensing device may include electrodes and electronic circuitry to monitor the electrical quantity of a substance, such as the capacitance or resistance of the moisture-retaining substrate, which is affected by the amount of water absorbed into the moisture-retaining substrate as moisture. In a preferred embodiment, the electrodes are arranged such that the moisture-retaining substrate is sandwiched between the electrodes. Alternatively, the electrodes may be arranged side-by-side, with the moisture-retaining substrate located therebetween. The water ingress determination unit is then adapted to determine the ingress of water into at least a portion of the internal structure of the housing (where the moisture-retaining substrate is positioned) based on the sensed functional parameters of the electrodes.

[0046] According to a second aspect of the invention, a method is provided for determining water ingress into at least a portion of the internal structure of a luminaire, wherein the method comprises the steps of: a) providing measurements of functional parameters of the luminaire, the luminaire including a lighting unit and a housing containing at least a portion of the lighting unit. The functional parameters indicate the functional characteristics of the luminaire affected by water ingress into at least a portion of the internal structure of the luminaire; and b) determining the water ingress into at least a portion of the internal structure of the luminaire based on the sensed functional parameters.

[0047] According to another aspect of the invention, a computer program product for determining water ingress into a luminaire is provided, wherein the computer program product includes program code means for causing a computer to execute the method according to the invention.

[0048] It should be understood that lighting systems, methods, and computer program products have similar and / or identical preferred embodiments, particularly as defined in the dependent claims.

[0049] It should be understood that preferred embodiments of the present invention can also be obtained by arbitrarily combining the dependent claims or the above embodiments with the corresponding independent claims.

[0050] These and other aspects of the invention will become apparent and will be elucidated with reference to the embodiments described below. Attached Figure Description

[0051] In the attached diagram below:

[0052] Figure 1 A lighting system is illustrated schematically and exemplary.

[0053] Figure 2 A method for determining water ingress into a lighting device is illustrated schematically and exemplary.

[0054] Figures 3A-3C Figures 4A-4C and 5 schematically and exemplary illustrate various aspects of preferred embodiments of the invention.

[0055] Figure 6 A graph is schematically and exemplaryly shown, depicting the principle of an embodiment for determining the inflow of water into a lighting fixture, and

[0056] Figure 7A and 7B An aspect of another preferred embodiment of the invention, including a moisture-retaining substrate, is illustrated schematically and exemplary. Detailed Implementation

[0057] Figure 1 A lighting system 100 with improved durability and safety is illustrated schematically and exemplary. The lighting system 100 includes a lighting unit 101 for providing light 107. The lighting unit 101 may, for example, include LEDs and circuitry for controlling the LEDs and providing power to them. However, the lighting unit 101 may also include any other light source that can provide light 107. Optionally, the lighting unit 101 also includes a control unit, which is implemented, for example, as dedicated hardware or software running on a general-purpose computing device, wherein the control unit is adapted to control the lighting unit 101, particularly controlling the light 107 provided by the lighting unit 101. However, if the lighting unit 101 provides other functions, the control unit may also be adapted to control other functions of the lighting unit 101.

[0058] Furthermore, the lighting system 100 includes a housing 102, which includes the LED in this example and at least a portion of the circuitry provided with the LED as part of the lighting unit 101. Preferably, the housing 102 includes a transparent portion (e.g., Figure 1 The dome-shaped portion shown) and the non-transparent portion (e.g. Figure 1 The portion 1 below the lighting unit 101 shown, this non-transparent portion can be considered as the construction base to which the lighting unit 101 can be attached, and which provides stability for the luminaire formed at least by the lighting unit and the housing. Typically, the housing 102 can take many shapes and designs, determined and selected based on the intended application of the luminaire and the chosen mounting system for the corresponding luminaire. Furthermore, the lighting system 100 (particularly the luminaire defined by the lighting unit 101 and the housing 102) includes at least a sensing device 103, wherein the sensing device 103 is adapted to sense functional parameters indicating functional characteristics of the luminaire, which are affected by water ingress into the internal structure of the luminaire (e.g., into the housing 102 of the luminaire and / or into the circuitry of the lighting unit 101). The functional parameter measured by the sensing device 103 can refer to any parameter that allows inference of the effect of water ingress on the functional characteristics of the luminaire. For example, the functional parameter can refer to the temperature measured within the housing 102 of the luminaire, wherein changes in the temperature measurement provided by the sensing device 103 as a functional parameter can indicate water that has entered the housing 102 of the luminaire. However, other functional parameters can also be measured by sensing device 103, such as the pressure within the housing 102 of the illuminator, the deformation of the housing 102 of the illuminator, etc. Thus, sensing device 103 can be implemented based on the functional parameters that should be measured by sensing device 103. For example, if the functional parameter is chosen to refer to the temperature within the housing 102, then sensing device 103 can be implemented by any known temperature sensor (e.g., a thermocouple). Furthermore, if pressure, as a functional characteristic of the illuminator, should be detected, then sensing device 103 can be implemented by any pressure sensor (e.g., a piezoelectric sensor) that allows determination of the pressure or pressure difference within the housing 102.

[0059] The lighting system 100 further includes a water ingress determination unit 104, which can be implemented as dedicated hardware or software running on a general-purpose computing system. The water ingress determination unit 104 can be provided as part of the illuminator, for example, coupled to a circuit board that also provides circuitry to control the lighting unit 101 of the illuminator. However, the water ingress determination unit 104 can also be provided externally to the illuminator, particularly on a different device (such as a user device). In a preferred embodiment, the water ingress determination unit 104 is implemented as a software application running on a user computing system such as a smartphone, server, or laptop computer. Typically, the water ingress determination unit 104 is adapted to receive functional parameters sensed by the sensing device 103 of the lighting system 100. For example, the water ingress determination unit 104 may be connected to the sensing device 103 via a wired connection provided on a circuit board, or via a wireless connection between the sensing device 103 and the water ingress determination unit 104, or via an indirect connection using an intermediate system (such as a server, to which a light source provides functional parameters measured by the sensing device 103; a memory that stores the sensed functional parameters; a gateway connecting the sensing device 103 and the water ingress determination unit 104, etc.). Optionally, the water ingress determination unit 104 may also include an input unit 105 (such as a keyboard, switch, contact sensor, etc.) and / or an output unit 106 (such as a display, light output system, audio output system, etc.).

[0060] The water ingress determination unit 104 is adapted to determine the ingress of water into at least a portion of the internal structure of the luminaire based on one or more sensed functional parameters. For example, the water ingress determination unit 104 may utilize a functional relationship between the sensed functional parameters and a large amount of water present in at least a portion of the internal structure of the luminaire (e.g., within the housing 102). Such a functional relationship can be provided to the water ingress determination unit 104 from a memory storing such relationships. Typically, such a functional relationship can be determined based on experiments performed, for example, at a construction site with luminaires of the same type. In this context, multiple functional parameters of the luminaire can be measured using different amounts of water present within the housing 102 of the luminaire. Based on such measurements, the functional relationship can be determined using known statistical methods and can be provided, for example, in the form of a mathematical relation; a lookup table; or a set of rules that the water ingress determination unit 104 can apply to the functional parameters measured by the sensing device 103.

[0061] The result of water ingress determination by water ingress determination unit 104 may, for example, refer to determining the absolute or relative amount of water present in at least a portion of the luminaire. However, the result may also be a simple determination of the presence of water in at least a portion of the luminaire. The result of water ingress determination may then be provided to the user by water ingress determination unit 104, for example, using output unit 106, and the result of water ingress determination may, for example, refer to a visible or audible output indicating water ingress into the luminaire. Furthermore, the output may also refer to providing additional information about the determined water ingress, such as an estimate of the severity of the impact of water ingress on the luminaire's function, whether the user should contact the installer to repair or replace the luminaire or a part of the luminaire, etc. Additionally or alternatively, water ingress determination unit 104 may also be adapted to provide the result of water ingress determination to the luminaire itself, for example, via wired or wireless communication with the luminaire, so that the controller of the luminaire (in particular the controller of lighting unit 101) can use the result of water ingress determination to control the luminaire, particularly the lighting unit 101 that controls the luminaire. For example, if the water ingress determination unit 104 determines that the amount of water present in the internal structure of the luminaire may pose a safety risk (e.g., due to the possibility of a short circuit) as a result of the water ingress determination, this information can be used by the luminaire's controller to cause the power supply to the luminaire to be turned off. In one embodiment, the controller can also use the water ingress determination result to control the luminaire unit 101 based on the water ingress determination result. For example, the controller can be configured to adapt (i.e., increase or decrease) the light intensity of the light 107 provided by the luminaire unit 101 based on the water ingress determination result. Furthermore, the control of the luminaire unit 101 by the controller can also be used to indicate the water ingress determination result to the user at certain points in time (e.g., shortly after the luminaire unit 101 is turned on), for example, by changing the color of the light 107 provided by the luminaire unit 101, by providing a flashing pattern of the light 107 provided by the luminaire unit 101, etc.

[0062] Figure 2 A method for determining water ingress into a luminaire is illustrated schematically and exemplary. Method 200 includes providing information about the luminaire (e.g., for example, regarding water ingress into a luminaire). Figure 1The first step 210 is to measure the functional parameters of the described illuminator. For example, the measurement can be provided by the illuminator's sensing device 103. However, the measurement can also be provided by a measurement providing unit, which can be implemented, for example, as a storage unit storing the measurement values ​​of the sensing device 103. Furthermore, the method includes a step 220, which determines, based on the sensed functional parameters, for example, using the water ingress determination unit 104 as described above, the ingress of water into at least a portion of the illuminator's internal structure. Optionally, the method 200 may also include, for example, providing the result of the water ingress determination to a user using the output unit 106 of the illuminator's lighting unit 101 or the water ingress determination unit 104. Additionally or alternatively, the method may also include, for example, controlling the lighting unit 101 of the illuminator using a controller based on the result of the water ingress determination.

[0063] In the following description, some preferred embodiments will be described in more detail. In a preferred embodiment, the sensing device 103 is adapted to monitor the deformation of the illuminator housing 102 caused by an increased pressure differential due to humidity, which is a functional parameter. Typically, the sealing of a illuminator (e.g., housing 102) significantly reduces the illuminator's ability to rapidly reduce pressure fluctuations, not only for positive fluctuations (i.e., overpressure) but also for negative fluctuations (i.e., vacuum). It is generally known that a pressure differential occurs when the illuminator is switched on and off. Furthermore, it is also generally known that this pressure differential can be used to determine whether a sealed illuminator is able to maintain a pressure differential, which can be an indication of a leakage path to the external environment.

[0064] In this context, it can be observed that water ingress also modifies the general pressure fluctuation behavior of the luminaire independently of the occurrence of a leakage path. Therefore, preferably, in one embodiment, the sensing device 103 is adapted to provide a pressure distribution as a functional parameter, more preferably a differential pressure distribution, i.e., the distribution of the pressure difference between the interior of the luminaire (e.g., the interior of housing 102) and the exterior of the luminaire, which is generated, for example, by monitoring the pressure inside the luminaire within housing 102 over a period of time (preferably 24 hours). The water ingress determination unit 104 is then adapted to compare the pressure distribution with a baseline pressure distribution determined when no water is present in the internal structure of the luminaire, for example, directly after the installation of the luminaire. Based on this comparison, particularly based on the difference between the two distributions, the water ingress determination unit 104 can then be adapted to determine whether water ingress has occurred, i.e., whether water is present in the luminaire.

[0065] In one embodiment, the sensing device 103 is adapted to provide the pressure distribution of the illuminator as a functional parameter without actually measuring the pressure. Figures 3A-3CAn embodiment is shown, wherein the sensing device 103 refers to a strain gauge 302 placed on the illuminator surface 301 of the housing 102 (e.g., Figure 3A As shown, there is no deformation). Utilizing the deformation of strain gauge 302 (such as...) Figure 3B and 3C As schematically shown (for positive and negative deformation), the deformation of the luminaire housing 102 due to the pressure difference with the external environment can be measured. Figures 3A-3C As shown, the strain gauge 302, as a sensing device, preferably provides a strain-sensitive pattern of the electrical conductor 304. A terminal 303 is provided at the end of the conductor 304, and the electrical characteristics of the conductor 304 can be determined at the end of the conductor 304. Figure 3B As shown, the deformation of the housing 102 causing tension leads to the elongation of the strain gauge 302, and thus to the narrowing of the conductor 304', and thus to an increase in resistance at the terminal 303. However, as Figure 3C As shown, the deformation leading to compression causes the strain gauge 302 to shorten, and thus the conductor 304 to thicken, and thus the resistance at the terminal 303 to decrease. Therefore, the strain gauge 302 provides an easy and simple way to measure the pressure difference between the inside and outside of the illuminator.

[0066] In a preferred embodiment, a portion of the illuminator housing 102 is configured to be more flexible than the rest of the housing 102 to enhance deformation due to pressure differential. The sensing device 103 can then be placed on the surface of the more flexible portion, i.e., on this deformable illuminator portion, for example in the form of a copper track serving as a simple strain gauge.

[0067] In this example, the sensing device 103 can also be as follows: Figures 4A-4C The MEMS pressure sensor shown is provided in the form of a pressure sensor. In this example, a piezoresistive sensor 412 constructed according to the strain gauge principle is applied at the edge between the more flexible portion 411 and the rest of the housing 410. Preferably, for the MEMS sensor, the more flexible portion 411 refers to a thin silicon film that changes the piezoresistive force of the piezoresistive sensor 412 at the edge of the flexible portion 411 upon deformation 420.

[0068] As an alternative to a strain gauge, a piezoresistor can also be used as the sensing device 103 to measure the mechanical force on a lighting fixture housing component caused by the pressure difference with the external environment. The piezoresistor passively generates a voltage that depends on the degree of mechanical deformation it undergoes.

[0069] Figure 5An embodiment of a typical watertight luminaire housing 500 is shown. In the watertight luminaire housing, a flexible rubber seal 510 is typically disposed between different portions of the housing 530, 520 and serves to make the housing watertight. In this embodiment, a portion of the rubber seal 510 may be provided with a sensing device 103, which may be in the form of, for example, a piezoresistor. Due to the generally flexible nature of the rubber seal 510, if a positive pressure differential to the external environment exists, the rubber seal 510 will mechanically expand in the directions of both portions of the housing 530, 520, whereby this expansion can then be measured by the sensing device 103. In a particular embodiment, the sensing device 103 (e.g., in the form of a piezoresistor) may be positioned in direct contact with the rubber seal 510 and is therefore adapted to measure the expansion of the seal, wherein the degree of expansion of the rubber seal 510 subsequently indicates the pressure differential between the inside and outside of the luminaire. In another specific embodiment, as shown in FIG. 5, the downward force on the luminaire cover (i.e., the seal) can be measured as a functional parameter. For example, if the external pressure on the illuminator is higher than the internal pressure inside the illuminator, this results in a force on the illuminator cover (i.e., the upper housing portion) 530. The sensing device 103 can then be adapted to monitor this force as a functional parameter, wherein the sensing device 103 can be a piezoresistor placed directly below the rubber seal 510, i.e., between the rubber seal 510 and a portion of the housing (e.g., the lower housing portion 520). Additionally or alternatively, an additional mechanical component (e.g., a rod) can be vertically positioned between the upper housing portion 530 and the lower housing portion 520. If the pressure on or a portion of the housing increases, the sensing device 103 (e.g., a piezoresistor located below the rod, i.e., between the rod and a portion of the housing 530, 520) can be adapted to detect the presence of the actual pressure difference. Based on these measurements, the water ingress determination unit 104 can then be adapted to infer water ingress.

[0070] In one embodiment, the pressure difference between the interior and exterior of at least a portion of the housing is measured over time. This pressure difference can be caused by environmental changes, such as temperature variations in ambient temperature due to sunlight, such that for a closed housing, a reference pressure difference can be recorded as having a specific shape. Exemplarily, the reference pressure difference includes a daily repeating shape dependent on sunrise and sunset. In the case of a substantially closed housing, the pressure difference is higher than in a substantially leaking housing, such that ingress water originating from a leaking housing within at least a portion of the housing can be determined by determining the deviation of this pressure difference from the reference pressure difference.

[0071] In one embodiment, the water entry determination unit can use the ideal gas law to determine water entry. The ideal gas law is typically written in empirical form as:

[0072] PV = nRT,

[0073] Where P, V, and T are pressure, volume, and temperature, respectively, n is the amount of substance, and R is the ideal gas constant. In the case of a sealed luminaire, the gas volume is constant at each definition, while the gas temperature and pressure can vary. For example, after the luminaire (especially the lighting unit) has changed from an on state to an off state, heat dissipation of the lighting unit and electrical circuitry ceases. Therefore, the internal temperature of the luminaire will decrease according to a specific temperature and pressure distribution, which depends on the temperature of the luminaire and the external ambient temperature. Water entering the luminaire alters the temperature and pressure distribution during changes in the luminaire's state. For example, when the luminaire is subjected to water ingress, gas will leave and enter the housing during the cooling phase of the luminaire. Therefore, if water is present in the luminaire (i.e., the luminaire), the heat and pressure distribution within the luminaire housing will deviate from the normal baseline distribution recorded in the absence of water, such as when the luminaire is being put into production or beforehand measured in the field for that particular luminaire prior to the water ingress event. As mentioned above, pressure distribution can be monitored in various ways by sensing devices, for example, by utilizing MEMS pressure sensors. To monitor temperature distribution, the sensing device may be equipped with a corresponding temperature sensor, such as a thermocouple, either alternatively or additionally.

[0074] It was also observed that water or humid air accumulating inside the luminaire's housing can increase the luminaire's thermal mass, i.e., its ability to adapt its temperature relative to a corresponding temperature stimulus. Therefore, when compared to a dry luminaire, for example, when the luminaire's functional state changes, the presence of water will slow down the rate of temperature change. For instance, in the case of transitioning between different dimming levels (i.e., dimming states), the luminaire's rate of adaptation to the new temperature will decrease. Thus, the presence of water can affect the temperature transition distribution of the luminaire.

[0075] Therefore, in one embodiment, the sensing device is adapted to measure the temperature distribution, i.e., the temperature changing over time, which is a functional parameter within the illuminator. For example, the temperature distribution can be easily measured when the sensing device refers to an embedded temperature sensor in the form of any microcontroller located within the housing, or a dedicated thermocouple within the illuminator. Furthermore, it is preferred that both humidity and temperature are measured by the sensing device, such as a single MEMS sensor. The compact size of the MEMS sensor allows for easy integration with existing electronic circuitry in the lighting unit.

[0076] Figure 6Experimental results for a sealed luminaire are shown. Figure 600 shows a thermal model of the different temperature response curves recorded by three different internal temperature sensors within the luminaire's housing, representing the on / off dimming transitions 611, 612, 613 and various dimming steps 611′, 612′, 613′ of the sealed outdoor luminaire. Because the thermal model provides a very good fit to the measured temperature response curves, the original measured temperature response curves are not visible "after" the thermal model curves. The y-axis 602 represents temperature, and the x-axis 601 represents time. At the bottom of the figure is shown the ambient air temperature 610, measured in the luminaire's environment during the transitions.

[0077] For each case, an empirical thermal model of the luminaire's response to dimming state transitions can be created for each transition based on the measured internal temperature. When the lighting unit is switched from an off state to an on state, the internal temperature of the luminaire will increase by a certain temperature due to heat dissipation from the lighting unit's engine and driver. The temperature increases exponentially with time. The same principle can be used when the lighting unit is turned off and the luminaire's internal components cool down. For example, for the temperature during the on / off transition, a model can be determined from the measured temperature distribution by applying the following equation and determining the corresponding constants in the equation based on the measured temperature distribution:

[0078]

[0079] Here, T refers to temperature, t refers to time, T0 refers to the internal temperature of the illuminator in its initial state, and T... end T refers to the internal temperature of the illuminator in the switched state, and τ is the time constant. The time taken to reach this thermal equilibrium state depends on the thermal capacitance of the illuminator, which determines the time constant τ. Due to heat dissipation from the lighting unit engine and driver, T... end -T0 describes a temperature increase / decrease caused by the on / off transition. In the case of leaky illuminators, the actual temperature distribution will deviate from the expected distribution based on the thermal model. For example, for Figure 6 The experimental results shown indicate that the thermal model refers to:

[0080]

[0081] Here, the identifier i refers to the corresponding measurement. The min(-t, 0) operator enables positive t to model heating using a portion of an exponential curve, where, in the case of negative t, the result of the model function is constant and refers to the initial temperature T0 or T... i0 .

[0082] As noted above, water ingress will alter the thermal properties of the luminaire, and therefore the measured dynamic temperature distribution recorded after the luminaire (i.e., the lighting fixture) has transitioned to a new dimming state will begin to deviate from the modeled baseline distribution measured in the absence of water ingress. Therefore, the water ingress determination unit can be adapted to determine water ingress based on a comparison of the temperature distribution measured during the transition between two functional states of the luminaire with the modeled baseline distribution of that transition.

[0083] like Figure 6 As shown, the modeled reference temperature distribution provides an accurate fit to the temperature measured by the sensing device during transitions between different lighting dimming states. Therefore, it is preferable that the water ingress determination unit is adapted to apply a change detection algorithm to the temperature distribution measured by the sensing device (here, a temperature sensor) to infer, for example, water ingress and / or air leakage due to leakage in the housing. Figure 6 The image shows three different sensor locations. For this embodiment, the placement of the sensing device is not critical, and the sensing device can be placed anywhere that allows inference of the temperature within the internal structure of the illuminator.

[0084] Figure 7A and 7B An aspect of another preferred embodiment of the invention, including a moisture-retaining substrate, is illustrated schematically and exemplary. In this embodiment, the sensing device in the illuminator is a humidity sensor 700, and preferably includes an upper electrode 701 and a lower electrode 702, which clamp a moisture-retaining substrate 703. The moisture-retaining substrate 703 is preferably a salt or a conductive plastic polymer and may be positioned together with the electrodes 701, 702 on a glass substrate 704. If moisture (i.e., water molecules in humid air) is absorbed by the moisture-retaining substrate 703, the moisture-retaining substrate 703 releases ions, thereby increasing the conductivity between the electrodes 701, 702. The change in resistance between the two electrodes 701, 702 is proportional to the relative humidity in at least a portion of the illuminator housing. Higher relative humidity reduces the resistance between the electrodes 701, 702, while lower relative humidity increases the resistance between the electrodes 701, 702.

[0085] In an embodiment, the water ingress determination unit may be adapted to estimate the outside air temperature based on temperature measurements from sensing devices within the internal structure of the luminaire using an empirical thermal model. In this case, when the estimated outdoor air temperature of the luminaire differs from the actual outdoor temperature, the water ingress determination unit may be adapted to determine the presence of water within the internal structure of the luminaire. The actual outdoor temperature may be provided to the water ingress determination unit, for example, by connecting to a weather server or connecting to the average air temperature of other nearby luminaires that communicate with the water ingress determination unit.

[0086] In one embodiment, the water ingress determination unit can be adapted to determine the relative humidity inside the luminaire based on the internal temperature and the degree of water accumulation. As daytime temperatures increase, more water gradually evaporates, resulting in a cooling effect. Accumulated water can evaporate completely. When all the water has evaporated, the humidity and temperature distributions of the luminaire will show different tortuosities, and the relative humidity will decrease as the internal temperature of the luminaire increases further. Based on the presence of tortuosities, the amount of water ingress can be inferred, for example, moderate water ingress that evaporates during the day but returns when the internal temperature of the luminaire decreases, where a large amount of water ingress significantly alters the thermal mass of the luminaire. Relative humidity also provides insight into condensation inside the luminaire. The advantages are as follows: leakage in the housing can be measured without knowing the external temperature of the luminaire, allowing for the measurement of condensation occurrence in both closed and leaking luminaire housings.

[0087] In one embodiment, the water ingress determination unit can also be adapted to determine minor water ingress events that only cause some condensation. Typically, to infer condensation occurring inside a particular luminaire, an understanding of when and where the relative humidity within the luminaire volume reaches 100% can be utilized. Condensation depends, for example, on temperature, the amount of water vapor present within the luminaire's internal structure, and the resistance to the diffusion of water vapor from the enclosed luminaire volume toward the surrounding environment. Temperature differences between the inside and outside of the luminaire can cause condensation at cold spots within the luminaire's internal structure. Such temperature differences can be triggered by changes in the outside air temperature or the internal temperature within the luminaire, or by changes in both the outside air temperature and the internal temperature within the luminaire. Sometimes, external temperature changes can be even drastic, such as during a sudden thunderstorm in a hot summer. When the temperature inside the luminaire drops rapidly, if the internal water vapor cannot exchange with the external environment quickly enough, the relative humidity within the luminaire's internal structure will also increase, depending, for example, on the total volume of the housing and the decrease in ambient temperature, and condensation will occur inside the luminaire. Condensation will then occur in the area inside the luminaire with the lowest temperature.

[0088] In one embodiment, external events causing drastic temperature changes (e.g., thunderstorms) are most likely to induce condensation, thus providing a good opportunity for the proposed sensing method to assess whether a particular illuminator has water accumulation. For example, measurements of functional parameters (such as the resistivity of the sump and / or internal temperature and humidity) can be recorded over a predetermined period, such as several weeks and / or months. In this case, similar external events (e.g., a series of thunderstorms) can result in similar patterns in the corresponding measurements of functional parameters, and the similarity of the events (e.g., thunderstorms) can be determined based on local weather data from another source (e.g., the internet or additional nearby weather sensors). In this case, a change detection algorithm can be applied to detect whether a change in illuminator characteristics has occurred during similar events, and when such a change occurred (indicating the time of water ingress) can be derived from the water ingress determination unit. Changes in the thermal and / or pressure behavior of the illuminator indicate that water ingress has occurred, whereas previously the interior of the illuminator was dry. Alternatively, data from a group of identical illuminators, for example, on a street or in a city, can be used to identify whether a change has occurred in one of the illuminators.

[0089] In one embodiment, functional parameters from a large number of illuminators (preferably located in relative proximity) are recorded, and an anomaly detection algorithm can be applied to the recorded measurements. Records (i.e., functional parameters) from other illuminators can be stored and / or provided to the water ingress determination unit via a functional parameter providing unit. When water ingress is a rare event occurring only at a small subset of illuminators, the functional parameters of the illuminators affected by water ingress will differ significantly from the majority of functional parameters from other “healthy” illuminators. Different anomaly detection techniques can be applied by the water ingress determination unit, such as unsupervised, supervised, or semi-supervised anomaly detection techniques. Unsupervised anomaly detection techniques involve detecting anomalies in an unlabeled measurement dataset, assuming that the majority of instances in the measurement dataset from various illuminators are normal, by finding instances that appear to be the least matched to the remainder of the dataset. Supervised anomaly detection techniques involve labeling one dataset as “normal” and another dataset as “abnormal” and training an algorithm to classify the other dataset as “normal” or “abnormal.” Semi-supervised anomaly detection techniques can include measures of the two techniques described above.

[0090] In one embodiment, the sensing device may be further adapted to directly measure condensation or moisture. In such an embodiment, the illuminator (particularly the housing) is adapted such that condensation is collected in a countersunk hole, for example, by gravity when humid air condenses due to low temperature. The presence of water in the countersunk hole is then monitored by the sensing device. In this case, the sensing device may, for example, refer to two pads connected to electronic circuitry, thereby creating a short circuit between the two pads in the presence of water. However, instead of a countersunk hole, a moisture or water retention substrate may be provided in the illuminator. In this case, the sensor device may refer to two electrodes placed in contact with the water or moisture retention substrate, such that the sensing device can monitor the resistance of the water or moisture retention substrate. The water entry determination unit may then be adapted to detect the presence of condensation using measurements performed by the sensing device. Furthermore, the water entry determination unit may be adapted to verify the results of the water entry determination based on functional parameters using directly measured condensation. Specifically, when a large amount of water is determined in the internal structure of the illuminator based on functional parameters, the water entry determination unit may be adapted to additionally consider the results of the directly determined condensation. For example, the amount of water entering the determining unit can be determined using a functional relationship between the amount of condensate, the amount of water vapor, and the functional parameters of the lighting device.

[0091] Although the lighting unit in the above embodiment includes an LED as a light source, any other lighting unit, such as a halogen lamp, fluorescent lamp, etc., may also be used.

[0092] Despite Figure 1 In one embodiment, the housing of the luminaire includes a dome-shaped portion that serves as a transparent part; however, in other embodiments of the luminaire, the transparent portion of the housing may be planar, for example, as exemplarily used as a spotlight for a street light.

[0093] Although water ingress is typically identified within the housing of the luminaire in the above embodiments, it is also possible to identify water ingress only in a part of the housing, throughout the entire housing, or in the internal structure of the housing.

[0094] Although the lighting system in the above embodiments typically includes only one illuminator, it may also include multiple illuminators. In this case, preferably, multiple illuminators work together to perform tasks, such as illuminating roads, paths, etc., or guiding road users in situations such as escape routes or emergency exits. Furthermore, the lighting system may be adapted to communicate with other lighting systems, for example, as part of a network of lighting systems. In both embodiments, preferably, the water ingress determination unit for the illuminator is adapted to receive functional parameters of more than one illuminator and to determine the water ingress into the illuminator based on a comparison of the functional parameters of the different illuminators.

[0095] By studying the accompanying drawings, the disclosure, and the appended claims, those skilled in the art can understand and implement other variations of the disclosed embodiments in practicing the claimed invention.

[0096] 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.

[0097] A single unit or device can perform the functions of several items as described in the claims. The simple fact that certain measures are described in mutually different dependent claims does not indicate that a combination of these measures cannot be used advantageously.

[0098] Processes such as determining the inflow of water into the luminaire, and controlling the lighting units of the luminaire by one or more units or devices, can be performed by any other number of units or devices. These processes can be implemented as program code devices of computer programs and / or dedicated hardware.

[0099] Computer program products may be stored / distributed on suitable media such as optical storage media or solid-state media, provided together with or as part of other hardware, but may also be distributed in other forms such as via the Internet or other wired or wireless telecommunications systems.

[0100] Any reference numerals in the claims should not be construed as limiting the scope.

[0101] This invention relates to a lighting system comprising: a lighting unit; a housing housing at least a portion of the lighting unit, wherein the lighting unit and the housing are part of a luminaire; and a sensing device positioned at or within the housing, wherein the sensing device is adapted to sense functional parameters indicative of functional characteristics of the luminaire, the functional characteristics being affected by water ingress into at least a portion of the luminaire. Furthermore, the lighting system includes a water ingress determination unit adapted to determine water ingress into at least a portion of the luminaire based on the sensed functional parameters. Therefore, a lighting system is provided that allows water ingress into the luminaire to be determined before water may damage the luminaire, thereby improving the durability and safety of the luminaire.

Claims

1. A lighting system (100), comprising: Lighting unit (101) adapted to provide visible light (107). A housing (102) comprising at least a portion of the lighting unit (101), wherein the lighting unit (101) and the housing (102) are parts of the illuminator. A sensing device (103), positioned at or within the housing (102), is adapted to sense functional parameters indicating functional characteristics of the illuminator, which are affected by water ingress into at least a portion of the internal structure of the illuminator, wherein the functional characteristics refer to features of the illuminator that are functionally related to its function; wherein the sensed functional parameters indicate the pressure distribution of the pressure difference between the interior and exterior of the illuminator over a time period and / or indicate the temperature distribution of the illuminator measured during a change in the illuminator from one operating state to another; and Water ingress determination unit (104) is adapted to determine the ingress of water into at least a portion of the internal structure of the luminaire based on a sensed functional parameter by utilizing a functional relationship between the amount of water and / or water vapor present in the internal structure of the luminaire and the sensed functional parameter.

2. The lighting system according to claim 1, wherein the water ingress determination unit (104) is adapted to determine water ingress into at least a portion of the internal structure of the luminaire by comparing the sensed functional parameters with a predetermined reference to the parameters.

3. The lighting system according to claim 2, wherein the reference of the functional parameters is based on a parameter model predetermined therein, the parameter model being adapted to model the functional parameters of the lighting unit (101) in relation to the surrounding environmental conditions and / or operating state and / or water ingress state of the lighting unit (101).

4. The lighting system according to claim 1, wherein the sensing device (103) is adapted to sense functional parameters of the illuminator under different operating states of the lighting unit (101), and wherein the water ingress determination unit (104) is adapted to determine water ingress into at least a portion of the internal structure of the illuminator based on a comparison of the functional parameters determined under different operating states of the lighting unit (101).

5. The lighting system according to claim 1, wherein the sensing device (103) is positioned at the housing (102) of the illuminator and adapted to sense deformation of at least a portion of the housing (102) as a functional parameter, the functional parameter indicating pressure within at least a portion of the housing (102) of the illuminator.

6. The lighting system according to claim 5, wherein the housing (102) comprises at least one flexible portion and a rigid portion, wherein the flexible portion is more flexible than the rigid portion, and wherein the sensing device (103) is adapted to sense the deformation of the housing (102) by sensing the deformation of the flexible portion of the housing (102).

7. The lighting system according to claim 1, wherein the sensing device (103) is adapted to sense a mechanical force applied to at least a portion of the housing (102) as a functional parameter, the functional parameter indicating the pressure within at least a portion of the housing (102) of the illuminator.

8. The lighting system according to any one of the preceding claims, wherein a further sensing device is provided, the other sensing device being adapted to sense a humidity parameter indicating the humidity within at least a portion of the housing (102) of the luminaire, wherein the water ingress determining unit (104) is adapted to further determine, based on the humidity parameter, water ingress into at least a portion of the internal structure of the luminaire.

9. The lighting system of claim 1, wherein the housing (102) includes a countersunk hole, the countersunk hole being provided such that water present in the housing (102) will accumulate in the countersunk hole, wherein, Another sensing device is adapted to sense the presence of water in the sinkhole.

10. The lighting system according to any one of claims 1-7 further includes a function parameter providing unit, the function parameter providing unit being adapted to provide function parameters with respect to another illuminator, which is part of the lighting system or outside the lighting system, wherein the water ingress determining unit (104) is adapted to receive the provided function parameters and is adapted to determine, based on the provided function parameters, water ingress into at least a portion of the internal structure of the illuminator.

11. A method for determining water ingress into at least a portion of the internal structure of a luminaire, wherein the method (200) comprises: Provides (210) a measurement of functional parameters of a luminaire, the luminaire comprising a lighting unit and a housing containing at least a portion of the lighting unit, wherein the functional parameters indicate functional characteristics of the luminaire affected by water ingress into at least a portion of the internal structure of the luminaire, wherein the functional characteristics refer to characteristics of the luminaire that are functionally related to the function of the luminaire; wherein the functional parameters indicate the pressure distribution of the pressure difference between the interior and exterior of the luminaire over a time period and / or indicate the temperature distribution of the luminaire measured during a change in the lighting unit from one operating state to another; as well as Based on the sensed functional parameters, the amount of water and / or water vapor present in the internal structure of the illuminator is used to determine (220) the water entering at least a portion of the internal structure of the illuminator.

12. A computer program product for determining water ingress into a luminaire, wherein the computer program product includes means for causing a computer to execute the method according to claim 11.

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