TECHNICAL FIELD
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The present invention relates to LED systems, specifically to LED lighting systems designed for environments where humidity can affect the operation and longevity of the LED luminaires. More particularly, it addresses the need for integrated humidity sensing solutions within outdoor or industrial lighting fixtures, enabling real-time detection and monitoring of internal humidity levels. The invention further pertains to predictive maintenance systems that utilize sensor data to forecast necessary repairs or replacements, ensuring operational efficiency and longevity of the luminaires.
BACKGROUND
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In the current state of the art, luminaires used in outdoor and industrial applications are often classified with high ingress protection ratings, such as IP66, which signifies resistance to dust and water intrusion. These luminaires typically rely on mechanical precision during assembly and proper sealing techniques to maintain their protective characteristics. However, mechanical stress during installation or field operation can damage the housing or seals, leading to water ingress, which can subsequently cause humidity build-up inside the luminaire. Over time, increased humidity can accelerate the aging of sensitive components, such as LED modules, leading to premature failure.
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State-of-the-art solutions do not offer a reliable means of detecting humidity ingress before significant damage occurs. Conventional methods rely on visual inspection or reactive maintenance, which is performed only after a failure has occurred. This approach leads to increased downtime and unplanned costs. Moreover, standard aging tests, such as the 85°C/85% relative humidity (RH) accelerated aging test, simulate harsh environmental conditions that LED modules might face. However, these tests cannot account for unexpected humidity build-up in situ, which is a common issue resulting from faulty installation, design weaknesses, or damage during use.
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To date, there are no affordable and effective solutions integrated within the luminaire to monitor real-time humidity levels and trigger preventive maintenance. As a result, many luminaires operate until they fail, without any early indication of the underlying issues caused by moisture ingress. The inability to detect and address humidity-related issues early leads to reduced operational life and efficiency of lighting systems, as well as higher maintenance and replacement costs.
SUMMARY
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In view of the above-discussed limitations, the objective of this invention is to provide a LED lighting system capable of detecting and responding to humidity levels within a sealed luminaire. Such a system offers real-time monitoring of environmental conditions to prevent moisture ingress, which can degrade LED components and reduce their operational lifespan. An additional objective of this invention is to address the lack of integrated, energy-efficient humidity sensing solutions that operate without additional wiring or complex controllers. This system is particularly valuable in outdoor and industrial environments where harsh conditions can lead to luminaire failures, though it is not limited to such applications.
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These and other objectives are achieved by the solution of this disclosure as described in the independent claims. Advantageous implementations are further defined in the dependent claims.
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According to a first aspect of the invention, a LED system is provided. The system includes a LED driver that provides a supply voltage at its output terminals, a LED load powered by these terminals, and a humidity sensor connected in parallel to the LED load. The LED driver comprises a controller designed for reading out a humidity information voltage signal via a voltage present at its output terminals. The humidity sensor provides a humidity information voltage signal.
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Advantageously, the humidity sensor operates using the existing LED power wiring, eliminating the need for additional components or external sensors. This design offers a cost-effective and simple method to integrate humidity sensing directly into the LED system. The elimination of extra wiring and controllers reduces complexity and installation costs while ensuring real-time environmental monitoring to prevent premature failure of the luminaire.
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According to an implementation form of the first aspect of the invention, the controller is configured to detect the humidity information voltage signal during a transient period, characterized by a change in voltage at the output terminals when powering up or shutting down the LED load.
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This feature improves the energy efficiency of the system, as the sensor only operates during these short periods of voltage change, rather than continuously. By detecting humidity only during the transient period, the system reduces power consumption while still ensuring effective moisture monitoring.
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According to a further implementation form of the first aspect of the invention, the controller is further configured to detect the humidity information voltage signal by analyzing a gradient of the voltage ramp-up or ramp-down at its output terminals during the transient period.
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Notably, the gradient reflects changes in the impedance of the humidity sensor, allowing the controller to accurately determine the humidity and temperature levels inside the luminaire. This configuration enhances the precision of the humidity detection process, enabling the system to provide early warnings of moisture ingress before damage occurs. The ability to detect fine changes in the voltage gradient allows for more accurate environmental monitoring, extending the lifetime of the LED components.
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According to a further implementation form of the first aspect of the invention, the humidity sensor is configured to operate during the transient period.
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In other word, the sensor remains inactive during the constant operation of the LED module. This feature ensures that the sensor is not continuously powered, which helps conserve energy and reduces sensor wear over time. Advantageously, this offers a significant advantage in terms of energy efficiency and sensor longevity, as the sensor is only active when necessary, reducing power consumption and extending the operational life of the system.
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According to a further implementation form of the first aspect of the invention, the humidity sensor comprises: a humistor that changes its impedance based on humidity and/or temperature inside the LED system, a discrete element that adjust the current flowing through the sensor based on the impedance change of the humistor, and a passive element that energizes the sensor during the transient period.
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This design ensures that the sensor provides accurate humidity readings with minimal energy input. The combination of a humistor with a current-modulating element improves the system's responsiveness to environmental changes, while the passive element ensures that the sensor is only powered during critical periods, enhancing both precision and efficiency.
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According to a further implementation form of the first aspect of the invention, the controller is configured to register and store a base level of the voltage ramp in a non-volatile memory as a reference for humidity measurements under predefined environmental conditions.
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Possibly, this reference value may be established during factory calibration or initial operation and is used to detect deviations in future readings. This feature provides long-term reliability in humidity detection, as it allows the system to account for variations in environmental conditions over time. By comparing current readings with a stored baseline, the system can more accurately track moisture ingress and signal when humidity levels deviate from normal operating conditions.
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According to a further implementation form of the first aspect of the invention, the controller is further configured to adjust the humidity reading based on ambient temperature, detected using a temperature sensor integrated within the LED driver.
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This configuration improves the accuracy of the humidity measurements by compensating for temperature fluctuations, which can otherwise distort the sensor's impedance readings. By integrating temperature compensation, the system provides more reliable environmental data, ensuring better protection of the LED components.
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According to a further implementation form of the first aspect of the invention, the controller is configured to generate an alarm signal if the voltage ramp gradient detected during the transient period exceeds to a predefined threshold indicative of sensor failure or absence.
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Optionally, the alarm can be communicated via a visual or acoustic signal, or sent as a bus signal through a standard communication protocol such as the Digital Addressable Lighting Interface (DALI) or other suitable communication networks. This feature enhances the system's safety and maintenance capabilities by providing early warnings of either sensor malfunction or excessive humidity levels. By sending alarms through standard communication protocols, the system can be integrated with larger building management systems, enabling timely interventions to prevent luminaire failure.
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According to a second aspect of the invention, a LED luminaire is provided. It includes a sealed casing housing the LED system as described in the first aspect or any implementation forms of the first aspect.
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This configuration ensures that the luminaire remains protected from external elements such as moisture and dust, while the integrated humidity sensor monitors internal conditions, enhancing the luminaire's longevity and reducing the risk of premature failure.
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According to a third aspect of the invention, a method is provided for detecting the humidity level within a LED system. The method involves reading a humidity information voltage signal via the output terminals of the LED driver during a transient period when the LED load is powered up or shut down.
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The method leverages the existing LED power infrastructure to perform humidity sensing, reducing complexity and installation costs while ensuring accurate humidity monitoring during transient voltage periods.
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According to an implementation form of the third aspect of the invention, the method includes detecting the humidity information voltage signal during a transient period, characterized by a change in voltage at the output terminals when powering up or shutting down the LED load.
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This method ensures that the humidity detection process is both accurate and energy-efficient, as it only operates during the brief periods when the voltage is changing, conserving energy and improving the system's overall performance.
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According to an implementation form of the third aspect of the invention, the method includes analyzing a gradient of the voltage ramp-up or ramp-down at its output terminals during the transient period.
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This enables precise measurement of humidity based on changes in the voltage ramp. Advantageously, the method's effectiveness is enhanced by ensuring that humidity levels are detected with a high degree of accuracy, using minimal power and existing system infrastructure.
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According to an implementation form of the third aspect of the invention, the method further comprises registering and storing a base level of the voltage ramp in a non-volatile memory as a reference for humidity measurements under predefined environmental conditions.
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This ensures long-term reliability by providing a consistent baseline for future humidity measurements, allowing for effective predictive maintenance and minimizing the risk of unexpected failures due to moisture ingress.
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According to an implementation form of the third aspect of the invention, the method further comprises adjusting the humidity reading based on ambient temperature, detected using a temperature sensor integrated within the LED driver.
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This improves the accuracy of the humidity readings, ensuring that changes in temperature do not lead to false humidity readings, thus protecting the LED system from environmental damage.
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According to a fourth aspect of the invention, an integrated controller for the LED driver is provided. This controller supports the method according to the third aspect, or any implementation forms of the third aspect, including: humidity detection by reading voltage signals, analyzing gradients, storing reference values, and adjusting humidity readings based on temperature.
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The integration of all these functions into the controller simplifies the overall system, making it highly efficient, reliable, and easy to integrate into a variety of luminaire designs.
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All steps that are performed by the various components described in this application, as well as the functionalities described to be performed by the various components, are intended to mean that the respective component is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external components is not reflected in the description of a specific detailed element of that component that performs that specific step or functionality, it should be clear to a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof.
BRIEF DESCRIPTION OF DRAWINGS
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The above-described aspects and implementation forms are now further explained with respect to the drawings by way of example only, and not for limitation. In the drawings:
- Fig. 1
- shows an exemplary LED system according to an embodiment of this invention; and
- Fig. 2
- shows a method according to an embodiment of this invention.
DETAILED DESCRIPTION OF EMBODIMENTS
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Illustrative embodiments of a LED system, a LED luminaire, a method, and an integrated control for a LED driver are described with reference to the figures. Although this description provides a detailed example of possible implementations, it should be noted that the details are intended to be exemplary and in no way limit the scope of the application.
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An embodiment/example may refer to other embodiments/examples. For example, any description including but not limited to terminology, element, process, explanation, and/or technical advantage mentioned in one embodiment/example is applicable to the other embodiments/examples. The same elements are labeled with the same reference signs and may function similarly or likewise.
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With respect to Fig. 1, an exemplary embodiment of a LED system 10 is illustrated. The LED system 10 includes the following components:
- A LED driver 11, which provides a supply voltage 12 at its output terminals 13, 14.
- A LED load 15 that is powered by the LED driver via the output terminals 13, 14.
- A humidity sensor 16 with two terminals, connected in parallel to the LED load 15.
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The LED driver 11 includes a controller (not shown in Fig. 1) that is configured to read out a humidity information voltage signal through the same output terminals 13, 14 used to supply the LED load 15. This integrated design reduces system complexity by using the existing LED power infrastructure for both lighting and humidity sensing.
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Optionally, the humidity sensor 16 comprises:
- A humistor, which changes its impedance as a function of the humidity and temperature inside the luminaire.
- A discrete element that adjusts the current flowing through the sensor based on the impedance change of the humistor.
- A passive element that energizes the sensor 16 only during transient periods, such as when the LED driver 11 ramps up or down the voltage at the output terminals 13, 14.
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In one embodiment, the controller is responsible for analyzing the voltage gradient during these transient periods, which corresponds to the humidity and temperature levels detected by the sensor 16.
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The controller detects the voltage ramp-up or ramp-down during the transient period, and analyzes the change in the voltage gradient (i.e., how quickly the voltage rises or falls). The gradient is directly proportional to the humidity levels within the luminaire, with higher gradients indicating higher humidity. Conversely, a smaller gradient signifies drier conditions.
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The system is designed such that, in the event of humidity sensor failure or if the sensor is absent, the voltage ramp gradient during the transient period is essentially equivalent to the maximum humidity condition. This results in a failure indication, signaling the user of a malfunction.
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In a preferred embodiment, the voltage ramp gradient becomes smaller as the detected humidity levels decrease, ensuring that the system can accurately detect varying humidity conditions. This transient period for the read-out of humidity information may occur over a duration of approximately 5 to 30 milliseconds, and more preferably between 10 and 25 milliseconds.
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If the detected voltage gradient corresponds to a predefined maximum threshold, the controller recognizes this as a sensor failure condition. This can occur if the sensor is absent or malfunctioning. Alternatively, if the voltage gradient exceeds a predefined humidity threshold, this indicates excessive humidity within the luminaire.
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Since humidity readings can be affected by temperature, in one implementation, the system further includes an integrated temperature sensor in the LED driver 11. The controller adjusts the humidity readings based on the ambient temperature detected by this sensor, ensuring that the readings are accurate regardless of environmental temperature fluctuations.
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To support predictive maintenance, the controller may be also configured to store a base level of the voltage ramp in a non-volatile memory. This reference level is established during factory calibration or an initial field operation period under predefined environmental conditions. Over time, the controller compares subsequent humidity readings to this reference value to detect deviations and monitor the gradual ingress of moisture.
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In a further embodiment, the system can trigger alarms if the humidity exceeds safe operational levels. The alarms can be communicated in various ways, including:
- Visual alarms, such as an indicator light on the luminaire.
- Acoustic alarms, such as an audible alert.
- Bus signals, such as via DALI or other communication protocols, to notify remote monitoring systems.
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The read-out humidity information can obviously be used in order to produce an alarm in case excessive humidity conditions are read out. The alarm could be visually or acoustically represented or preferably sent out via a bus signal, such as for example a DALI signal.
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In cases where humidity levels remain within acceptable limits, the system can still send humidity data over a DALI bus signal. This contributes to continuous maintenance monitoring by recording the humidity status over time. A slow increase in humidity-while still within acceptable levels-can indicate future risks and may have long-term impacts on the LED driver components, thus assisting in predictive maintenance decisions.
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The invention also encompasses a sealed LED luminaire that houses the LED system 10 shown in Fig. 1. The sealed casing ensures protection from external elements, while the integrated humidity sensor 16 monitors the internal environment for signs of moisture ingress. This setup is particularly beneficial for outdoor and industrial luminaires exposed to harsh conditions.
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With reference to Fig. 2, an embodiment of a method 200 for detecting the humidity level present in the environment of a LED system 10 is illustrated. The LED system 10 may be the system described in the previous embodiments, as shown in Fig. 1.
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The method 200 involves a step 201: reading out a humidity information voltage signal via a voltage present at its output terminal 13, 14.
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Optionally, the step 201 of reading out a humidity information voltage signal via a voltage present at its output terminals 13, 14 comprises the step 202 of detecting the humidity information voltage signal during a transient period, characterized by a change in voltage at the output terminals 13, 14 when powering up or shutting down the LED load 15.
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According to one embodiment, the step 202 of detecting the humidity information voltage signal comprises the step 203 of analyzing a gradient of the voltage ramp-up or ramp-down at its output terminals 13, 14 during the transient period.
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In a further embodiment, the method comprises registering and storing a base level of the voltage ramp in a non-volatile memory as a reference for humidity measurements under predefined environmental conditions.
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In a further embodiment, the method further comprises adjusting the humidity reading based on ambient temperature, detected using a temperature sensor integrated within the LED driver.
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In a further embodiment, the method further comprises generating an alarm if the humidity exceeds a predefined threshold or if the sensor fails. The alarms are communicated visually, acoustically, or via a bus signal, such as the DALI protocol, to ensure timely intervention.
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This method ensures efficient, real-time monitoring of the luminaire's internal environment and contributes to predictive maintenance by identifying potential failures before they occur.
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This invention further proposes an integrated controller within the LED driver 11, which is designed to manage the humidity detection process. It performs the method of Fig. 2, such as voltage readout, gradient analysis, base value storage, temperature adjustment, and alarm signaling. This integrated approach minimizes the need for additional components and allows the humidity sensor to function using the existing LED power infrastructure.
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To summarize, this invention offers a LED system 10 using existing wiring between the LED driver 11 and the LED load 15, eliminating the need for additional wires or external humidity controllers. In particular, the humidity sensor 16 is only powered during transient periods, reducing energy consumption and extending sensor lifespan. By continuously monitoring humidity levels and storing reference values, the system 10 enables predictive maintenance, reducing the risk of unplanned luminaire failures.
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Additionally, the integration of a humidity sensor 16 in a sealed luminaire helps prevent internal damage due to moisture ingress, improving the longevity of the LED system 10. The system is capable of detecting and signaling sensor failure or absence, ensuring reliable operation over time.
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This invention is particularly beneficial for outdoor and industrial lighting systems, where environmental exposure can lead to the ingress of moisture, potentially reducing the operational life of the LED luminaire. By integrating humidity detection, temperature compensation, and failure detection into a simple and efficient design, the invention offers a comprehensive solution for long-lasting and reliable LED systems.
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While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by limitation. Numerous changes to the disclosed embodiments can be made in accordance with the disclosure herein without departing from the spirit or scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above described embodiments. Rather, the scope of the invention should be defined in accordance with the following claims and their equivalents.
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Although the invention has been illustrated and described with respect to one or more implementations, equivalent alterations, and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In addition, while a particular feature of the invention may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.