LIGHT WITH SENSOR DEVICE FOR MEASURING REFLECTED AND AMBIENT LIGHT

Description

[0001] The present invention relates to a luminaire, in particular a street luminaire or an interior luminaire, with a sensor unit and a control unit which enable a spectral evaluation of the ambient light and the light reflected by the luminaire for the control of the luminaire.

[0002] Outdoor luminaires need to be switched on and off depending on the time of day. Normally, such luminaires are controlled using predefined times in the luminaire parameters, additional hardware on the luminaire (e.g., a Zhaga socket), or a central control infrastructure (SLC, Tvilight, etc.). Consequently, the luminous flux is adjusted only statically and through time-controlled, predefined dimming. However, a problem with this approach is that it cannot react dynamically to changing environmental conditions.

[0003] Furthermore, it is known to equip luminaires with light sensors to regulate the light output depending on the measured brightness. However, this system has the disadvantage, particularly outdoors, that the luminous flux of the luminaire cannot be adjusted depending on environmental conditions, especially fog, snow, etc.

[0004] From WO 2014 / 180647 A1, a street lighting luminaire with a light sensor is known, wherein the light sensor is specifically designed to measure specularly reflected light and scattered light separately. The ratio of these two quantities allows conclusions to be drawn about environmental or road surface conditions, and the luminaire is configured to adjust the luminous flux accordingly. However, this solution is relatively complex because the sensor must be configured to measure light from different solid angles, and a separate light source in the form of a laser is required to provide the measuring light for the sensor.

[0005] EP 2566303 A1 discloses a lighting system that uses indoor and outdoor light sensors to detect illuminance level and color. A lighting unit has controlled color and intensity, allowing a color adjustment zone to be defined where the interior lighting has a color temperature based on the outdoor light conditions.

[0006] WO 2010 11 5801 A1 discloses a retrofit LED module with a carrier with at least one LED, further with a retrofit socket for mechanical and electrical contacting with conventional lamp sockets and electronics for controlling the at least one LED, wherein at least part of the electronics is integrated into the carrier and the electronics comprise a light sensor, and / or a daylight sensor and / or a color sensor and / or the associated electronics for processing the signal.

[0007] The object of the present invention is to provide a structurally simple and cost-effective solution for a luminaire that allows the luminous flux of the luminaire to be adjusted to measured ambient conditions.

[0008] The problem is solved by a luminaire according to claim 1.

[0009] A special feature of the luminaire according to the invention is that both ambient light and reflected light from the luminaire's light source are measured and spectrally evaluated together. According to the present invention, the proportion of light reflected by the luminaire's light source itself, relative to the proportion of ambient light, can be determined from the spectral evaluation. Furthermore, the environmental conditions near the luminaire can then be inferred from the light intensity and the spectral distribution of the ambient light. According to the invention, a control unit for the luminaire is adapted to perform this evaluation of the light spectrum to detect environmental conditions and to control the luminaire's light source depending on the detected environmental conditions.

[0010] According to a preferred embodiment, the light source and the sensor unit are arranged behind a common transparent cover of the luminaire. This is not only simpler to implement structurally, but also offers the advantage that the sensor unit can receive the light from the luminaire's light source, which is reflected back from the cover, in addition to the ambient light that reaches the sensor from outside through the cover.

[0011] According to a preferred embodiment, the control unit is configured to determine sunrise, sunset, and / or the lunar phase from changes in the light spectrum throughout the day and to regulate the brightness of the light source based on one or more of these parameters. The light from the sun at different positions differs in its spectral composition from the light from the luminaire's own light source, enabling the control unit to distinguish between the two light components through its spectral resolution and to determine the sun's position. This information can then be used directly to regulate the brightness of the luminaire's light source. The same applies to the light from different lunar phases. Depending on the lunar phase, the brightness of the luminaire can thus be adjusted to the ambient light even at night.

[0012] According to a preferred embodiment, the control device is configured to determine changes in the proportion of light reflected by the light source relative to the light intensity emitted by the light source and to adjust the brightness of the light source based on the changing reflection conditions. The proportion of light reflected by the light source changes with the ambient conditions of the luminaire. For example, a higher proportion of light is reflected in fog, snow, or rain than in dry weather. Furthermore, these environmental conditions necessitate adjusting the luminous flux of the light emitted by the luminaire to the visibility conditions. Therefore, reflection measurement can be very effectively used to adjust the brightness of the light source.

[0013] According to a preferred embodiment, the control device is configured to determine the color temperature of the ambient light from the measured light spectrum, and the one light source, or the one light source in combination with other light sources of the luminaire, is configured to generate light of different color temperatures. The control device, depending on the measured color temperature, controls the at least one light source to change the color temperature of the emitted light, in particular to adjust it accordingly. This embodiment is preferred, for example, for interior luminaires. The natural light entering the interior through windows has a characteristic color temperature corresponding to the time of day. The interior lighting, which is intended to supplement this daylight, can be adjusted in color temperature to match the respective incident daylight.This creates the impression of natural daylight in the interior, although this is partly generated by artificial light.

[0014] According to a preferred embodiment, the control unit is configured to determine a temporal sequence of intensity fluctuations from the measured light intensity and, if a significant change in the intensity fluctuations is present, to infer a disturbance in the ambient light and adjust the light output of the light source accordingly. For example, branches in the vicinity of the light fixture can cast shadows. Due to the movement of the branches in the wind, these shadows have a characteristic that is easily distinguishable from other disturbances. The light output of the fixture can be adjusted in relation to this shading. Furthermore, it is possible that embodiments of the light fixtures also include an interface to transmit a corresponding message about the disturbance to a central control unit in order to eliminate the disturbance, if necessary.

[0015] According to a preferred embodiment, the control device is configured to infer aging of the light source from changes in the light intensity and / or the light spectrum of the light reflected from the light source and to adjust the control of the light source accordingly to compensate for this aging. The light sources of luminaires, e.g., LEDs, are known to decrease in intensity over their operating life at a given operating current. This effect can be compensated for by increasing the operating current. Furthermore, it is also known that light sources change their spectral distribution over time. This can also be compensated for in light sources whose color is electronically adjustable.Since the luminaire according to the invention already measures the spectral composition of the reflected light, the aging effects of the light source can be counteracted in a particularly simple way using this data by changing the luminous flux or the color of the light. In a further embodiment, it is even possible to infer a possible premature failure of the light source in the event of a significant deviation and to transmit this information from the control unit via a corresponding interface, so that maintenance work on the luminaire can be initiated.

[0016] According to a preferred embodiment, the control unit is configured to detect reflections from the headlights of passing vehicles based on characteristic temporal changes in the light spectrum and intensity of the measured ambient light, and to calculate the traffic volume from this. The control unit is further configured to adjust the light output of the light source according to the calculated traffic volume. The light from passing vehicles exhibits a characteristic temporal change. Furthermore, the spectral distribution of light from vehicles, even from different manufacturers, is known. Therefore, the control unit can use a suitable evaluation algorithm to deduce the number of passing vehicles from the sensor readings. This result can be used directly to control the light, for example, to adjust the brightness of the headlights.The system can increase the brightness of the light in heavy traffic. Furthermore, the light source can also be controlled by the control unit to reduce the light intensity within a specific angle from which a detected vehicle is approaching, thus minimizing glare for the driver.

[0017] Further features and advantages of the present invention will become apparent from the following description of preferred embodiments, which is given in conjunction with the accompanying figures. The figures illustrate the following: Figure 1 shows a street light according to one embodiment of the invention. Figure 2 shows a cross-section through the street light according to the invention. Figure 1 with light rays shown. Figure 3 shows the cross-section as in Figure 2 , furthermore with schematically represented ambient light. Figure 4 shows the lamp according to Figure 1with reflected light. Figure 5 shows a spectral composition measured by the sensor in a luminaire. Figure 6 shows a color temperature determined by the control unit of a luminaire as a function of the time of day. Figure 7 shows a light intensity measured by the sensor unit of a luminaire as a function of the time of day. Figure 8 shows the intensity after Figure 7 , where the light intensity of the light reflected by the luminaire is subtracted. Figure 9 shows a near-infrared component, calculated by the control unit of a luminaire, compared to the course of the day. Figure 10 shows a light intensity measured by the sensor unit compared to the course of the day with interfering influences.

[0018] In Figure 1 A is schematically an outdoor light for illuminating a section of road, at the edge of which it is arranged.

[0019] In Figures 2 and 3 are cross-sections through the outdoor light according to Figure 1The outdoor light fixture uses one or more LEDs (light-emitting diodes) as the light source 1. In addition to the LED, a sensor unit 2 is provided for detecting light, which, in the illustrated embodiment, is located on the same circuit board 3 as the LED 1. The assembly is covered by a transparent cover 4, e.g., made of glass, PC, or PMMA, with the sensor unit 2 and the light source 1 located behind the common cover. The light rays L1, L2, and L3 show exemplary light rays emanating from the light source 1. Reflections at the cover 4 generate light rays L21 and L22, which are directed back onto the sensor unit 2. Figure 3 is the same structure as in Figure 2The diagram shows the ambient light, except that a directional arrow 5 for the time-of-day-dependent ambient light is also schematically depicted. The ambient light 5 falls from the outside through the cover 4 onto the sensor unit 2. It should be understood that the direction of the light beam 5 is only shown as an example. Of course, light can strike the sensor unit 2 from the outside through the cover 4 from various directions.

[0020] Sensor unit 2 is designed to measure the incoming light not only in intensity but also with spectral resolution. Spectrally resolved typical measurement curves are shown in Figure 5The spectral resolution offers possibilities for detection, e.g., of the daily progression or sunrise and sunset. The invention provides various methods for this, which can be integrated into an algorithm within a control unit of the luminaire: a color temperature can be calculated from the measured spectrum. Based on the changing color temperature, as for example in Figure 6 As shown, it can be inferred whether it is morning or evening because the color temperature of the ambient light changes throughout the day due to the scattering of light in the atmosphere. Independently of this, the light reflected from light source 1 is also included in the light measured at the sensor unit. This is determined by the spectrum of the light source, independent of the time of day, and in this example, it is approximately 4,000 K. Figure 6This shows a representation of the color temperature over the course of the day. During the night hours, from approximately 7:00 PM to 7:30 AM, the color temperature remains approximately constant at 4,000 K. This means that during this time, no ambient light is measured; only the light reflected from light source 1 is measured at sensor unit 2. The control unit can therefore easily determine sunset and sunrise from the color temperature. Another possibility is to determine sunset and sunrise directly from the light intensity, as shown, for example, in... Figure 7As shown in the diagram, the light intensity remains almost constant during the night. This light component corresponds to the light reflected by light source 1, which does not change throughout the night. The decrease in total light intensity in the evening and the increase in the morning therefore indicate sunset and sunrise, respectively. Finally, in another embodiment, the infrared component resulting from the sun can be determined from the spectral composition, as shown in Figure 9 The infrared component can be determined, for example, from the ratio of the spectral components of red, green, and blue to the total intensity of the color white. This spectral difference provides direct information about the sun's path in the morning and evening.

[0021] Based on the data collected about sunrise and sunset times, the brightness of the light source can be regulated via a control unit (not shown in the figures). The light can also be adjusted to the desired brightness level during twilight hours. In addition to the twilight function, another option is to take the lunar phase into account. During a full moon, less artificial light is needed at night than during a new moon. Since the proportion of moonlight can also be determined from the spectral distribution of the measured ambient light, the proportion of artificial light at night can also be adjusted accordingly to achieve further energy savings. The light output of the luminaire can be individually parameterized on the luminaire itself.A fixed switching-on and switching-off time of the light source can also be defined, for example, as a switching threshold and / or with a hysteresis.

[0022] Another possibility offered by the embodiment of the lamp according to the invention is in Figure 4 depicted. As shown in Figure 1 An outdoor light is positioned along a street. However, the street is covered by weather conditions, such as wetness, ice, or snow. Furthermore, fog may also be present near the ground. These weather conditions increase the proportion of light emitted into and reflected back into the light fixture. The light beam L4 in Figure 4The diagram schematically illustrates this reflection or scattered light resulting from weather events. The increased amount of light detected by sensor unit 2, compared to a dry road, can be distinguished in the control unit from the ambient light, which changes throughout the day as described above. The altered road surface reflects the light from light source 2 in different ways depending on the weather conditions. Specular and / or diffuse reflection directly from the road surface can also alter the spectral composition of the reflected light. Therefore, the road surface cover can be analyzed in the control unit from the spectral composition of the reflected light L4. The differences in the spectral composition of the reflection and the light intensity can be used, for example, to determine the type of road surface (e.g., snow, ice, or wetness).This allows for better illumination of the road. For example, disruptive reflections in wet conditions can be avoided by reducing the brightness of the light, especially in a solid angle area where reflections from the road surface could cause glare for road users.

[0023] Furthermore, the sensor unit 2 can be used in Figure 3 to determine the color temperature of ambient light. Due to the spectral composition, as in Figure 5As shown, the color temperature can be calculated. This offers advantages for indoor luminaires, for example, for industrial applications in manufacturing plants or office buildings. By detecting the color temperature, the level of sunlight throughout the day can be determined. The indoor luminaire can then generate artificial light that adapts to the changing color of the light at the current stage of the sun's cycle. This, in turn, can promote the well-being of employees. Furthermore, this design can also detect changes in the light color due to the aging of the light source over its lifespan, allowing for the early detection of color shifts in the luminaire.

[0024] Significant changes or steep gradients in the measured light intensity can also indicate potential sources of interference, such as branch growth or passing cars near outdoor lights. Sensor unit 2 measures the incident sunlight during the day, which is affected by the shadows cast by branches. Because the branches or trees are constantly moving, significant changes occur, such as... Figure 10 The periodic behavior allows conclusions to be drawn about the disturbance variable. The disturbance variable can be addressed by adjusting the luminaire's luminous flux accordingly. Furthermore, the luminaire's control unit can be configured to transmit the disturbance information to a central control unit via an interface.

[0025] In addition, the following information can also be centrally transmitted by the control unit via a suitable interface: an age-related change in the light color of the lamp, a local weather condition at the location of the lamp, an indication of possible branch growth in the area of ​​the lamp, and / or special traffic volume by motor vehicles or illuminated bicycles.

[0026] The algorithm for detecting the various previously described events from the spectrally resolved light intensity of the captured ambient light or the reflected light can also be implemented using artificial intelligence. For example, measurements can be taken from a large number of luminaires and compared with actual detected events and weather conditions. From the training data, a significant pattern in light intensity and light spectrum can be derived based on the type of disturbance or weather condition. This pattern is then implemented in an algorithm for evaluating light intensity and light spectrum within the luminaire's control unit to detect corresponding events. REFERENCE MARK LIST

[0027] 1 Light source, especially LED 2 Sensor unit 3 Circuit board 4 Cover 5 Ambient light L1, L2, L3 Light beam from light source L4, L21, L22 Reflected light beam

Claims

1. Luminaire, in particular street luminaire or interior luminaire, having at least one light source (1) for emitting light of the luminaire and a sensor unit (2) which is configured to measure a light spectrum and a light intensity of ambient light (5) and light reflected by the light source (1), and a control device which is configured to evaluate the measured values of the sensor unit (2), wherein the proportion of the light reflected by the light source (1) of the luminaire itself in relation to the proportion of the ambient light (5) is determined from the spectral evaluation, and to control the light emission of the light source (1) as a function of the measured light spectrum and the light intensity, wherein the control device of the luminaire is configured to carry out this evaluation of the light spectrum and the light intensity in order to detect ambient conditions and to control the light source of the luminaire as a function of the detected ambient conditions.

2. Luminaire according to Claim 1, wherein the light source (1) and the sensor unit (2) are arranged behind a common transparent cover (4) of the luminaire.

3. Luminaire according to one of the preceding claims, wherein the control device is configured to determine one or more of the following parameters from a temporal change in the light spectrum over the course of the day: the sunrise, the sunset, and / or the moon phase, and to regulate the brightness of the light source (1) as a function of the one or more parameters.

4. Luminaire according to one of the preceding claims, wherein the control device is configured to determine a change in the light component reflected by the light source (1) in relation to the light intensity emitted by the light source (1) and to adapt the brightness of the light source (1) on the basis of the changed reflection conditions.

5. Luminaire according to one of the preceding claims, wherein the control device is configured to determine a color temperature of the ambient light (5) from the measured light spectrum, and the one light source (1) or the one light source (1) in conjunction with further light sources (1) of the luminaire is configured to generate light of different color temperatures, wherein the control device actuates the at least one light source (1) as a function of the measured color temperature in order to change, in particular to adapt, a color temperature of the emitted light as a function of the measured color temperature.

6. Luminaire according to one of the preceding claims, wherein the control device is configured to determine a temporal sequence of intensity fluctuations from the measured light intensity and, in the presence of a significant change in the intensity fluctuations, to infer a disturbance variable of the ambient light (5) and to adapt the light emission of the light source (1) as a function of the disturbance variable.

7. Luminaire according to one of the preceding claims, wherein the control device is configured to infer aging of the light source (1) from a change in the light intensity and / or the light spectrum of the light reflected by the light source (1) and to change the actuation of the light source (1) in accordance with the aging of the light source (1) in order to compensate for the aging.

8. Luminaire according to one of the preceding claims, wherein the control device is configured to detect a reflection of vehicle headlights of passing motor vehicles from a characteristic temporal change in the light spectrum and the light intensity of the measured ambient light (5) and to calculate a traffic volume therefrom, wherein the control device is furthermore configured to adapt the light of the light source (1) in accordance with the calculated traffic volume.