Lighting device for illuminating stages, film and photo shoots or for light shows

Abstract

The invention relates to a lighting device for illuminating stages, film and photo shoots, or for light shows, comprising a substrate and a plurality of LEDs mounted on the substrate, wherein the device has LEDs with at least four different peak wavelengths. According to the invention, the plurality of LEDs comprises one type of phosphor-converted yellow LED (PC Yellow), wherein the peak wavelength of the phosphor-converted yellow LED (PC Yellow) is in the range between 560 and 590 nm, and comprises at least two types of blue LEDs, wherein the peak wavelengths of the two blue LED types are in the range between 390 nm and 510 nm and wherein the peak wavelengths of the two blue LED types differ by at least 10 nm.

Description

[0001] The invention relates to a lighting device for illuminating stages, film and photo shoots or for light shows according to the preamble of the main claim.

[0002] Lamps or lighting devices can reproduce a wide color gamut by combining light from, for example, a variety of LED light sources with different wavelengths. White, in particular, is a color that is usually desired to be produced by a lamp with high quality and a desired color temperature. To produce white light, it is common practice to supply energy to all the LEDs in the lamp, thus producing white light with the highest possible luminous flux.

[0003] Modern LED theater spotlights or floodlights produce flicker-free white light in various color temperatures, measured in Kelvin. This allows LED lighting to create a very cozy, dim atmosphere, but also very bright, almost bluish light. When white light is produced by LEDs, it is often characterized by its closest similar color temperature (CCT), ranging from warm white (around 2500 K) to cool white (around 5000-6500 K). Generally, warm white is produced using less blue light and more red light, while cool white is produced using more blue light and less red light. In certain situations, a combination of these different light temperatures is also useful or interesting: for example, when a stage in a theater or musical is illuminated with warm white light, but a specific object or person is highlighted with a cool white spotlight.This example shows that LED technology is more flexible than conventional headlights usually are.

[0004] Besides color temperature, light can be characterized by its ability to accurately reproduce color on a subject. The Color Rendering Index (CRI) provides a representation of how accurately an artificial light produces the full range of colors on a subject compared to a standardized source (usually a source representing an incandescent bulb or daylight). A perfect CRI score is 100, indicating that the artificial light source reproduces color to the human eye just as well as the standardized source. To assess the quality of an LED spotlight, the lumen is also used: the "radiant output" or illuminance of a spotlight. Simply put, the more lumens, the brighter the light source. Very bright theater spotlights produce around 50,000 lumens.The more common unit is lux, which measures the brightness of an illuminated area, while lumens indicate the brightness of the light source. Daylight has a value of 15,000 to 100,000 lux. A light source with 50,000 lumens can therefore illuminate half a square meter with the brightness of direct sunlight, or about 7 meters. 2 illuminate it with the brightness of a cloudy sky.

[0005] Currently common LED spotlights or lighting devices of this type feature, in addition to the typically present narrowband RGB (red, green and blue) colors, a combination of broadband (phosphor converted) LEDs such as PC Amber and / or PC Lime or white light sources.

[0006] In particular, generic LED illuminators are also known that comprise a combination of a lime / mint light source, which accounts for at least 25% of the total luminous flux, and a dark red light source, which accounts for at least 0.5% of the total luminous flux. An exemplary embodiment of such a device is described in German patent application DE 10 2019 120 298 A1. The LED illuminator can further comprise a cyan light source, which accounts for 1% to 50% of the total luminous flux. The cyan light source can, for example, account for 1% to 30% of the total luminous flux. In one embodiment, the cyan light source accounts for 2% to 10% of the total luminous flux. The LED illuminator can further comprise a red / red-orange light source, which accounts for 1% to 20% of the total luminous flux. The red / red-orange light source can, for example, account for 2% to 15% of the total luminous flux.A well-known example of a product on the market is the ETC "Lustr2" series from ETC Electronic Theatre Controls. Equipped with seven colors, this spotlight features red, green, blue, PC amber, cyan, PC lime / PC mint, and deep red combinations of different LEDs and is designed for use in theaters, film and TV studios, and exhibitions.

[0007] The greater the number of primary colors used, the better the desired target spectra, e.g., candlelight or daylight, can be approximated, thus achieving a better color rendering index (CRI). Typically, a closer approximation of the target spectrum leads to a lower system efficiency and therefore a lower maximum brightness compared to a less precise reproduction of the target spectra. This loss of brightness due to the sometimes inefficient mixing must be compensated for with very good and expensive optics. Ideally, both high efficiency, and consequently high light output, and good spectral light quality would be desirable.

[0008] Although very good quality (CRI values) can already be achieved with these well-known LED lighting devices at very high light outputs, further improvements in some areas are still desirable.

[0009] For example, there is room for improvement in the reproduction of very warm white light, such as when simulating candlelight. Furthermore, the aforementioned devices exhibit a rather high efficiency loss at a maximum CRI value of approximately 30-50% of the maximum nominal power.

[0010] The object of the present invention is therefore to provide a lighting device for illuminating stages, film and photo shoots, or light shows, which overcomes the disadvantages of known LED lighting devices. In particular, the LED lighting device should exhibit high spectral homogeneity in the generation of white light, achieve a very good color rendering index (CRI), show better production of warm white light (< 4000 K), demonstrate more efficient and uniform utilization of the individual LEDs, which also leads to more uniform aging processes, and enable better production of pure yellow light.

[0011] The problem is solved by a device according to claim 1.

[0012] The invention relates to a lighting device for illuminating stages, film and photo shoots, or for light shows, comprising a substrate and a plurality of LEDs mounted on the substrate, wherein the device has LED types with at least four different peak wavelengths. According to the invention, the plurality of LEDs comprises one type of phosphor-converted yellow LED (PC Yellow), wherein the peak wavelength of the phosphor-converted yellow LED (PC Yellow) is in the range between 560 and 590 nm, and comprises at least two types of blue LEDs, wherein the peak wavelengths of the two blue LED types are in the range between 390 nm and 510 nm and wherein the peak wavelengths of the two blue LED types differ by at least 10 nm.

[0013] A phosphor-converted yellow LED (light-emitting diode, PC yellow) is a special type of LED that typically produces yellow light by combining blue or ultraviolet (UV) light-emitting semiconductor materials with a phosphor conversion element. The required components include the semiconductor material, typically gallium nitride (GaN) or indium gallium nitride (InGaN), which is responsible for emitting blue or UV light. A phosphor is also needed to convert the emitted light into yellow light; commonly used phosphors are based on yttrium aluminum garnet (YAG) or other rare earth elements. The entire system is mounted on a substrate, usually ceramic or silicon. A transparent or translucent housing is required to protect the LED and efficiently emit the light.Finally, a control unit is needed to supply and control the LED with the correct voltage and current.

[0014] Such an LED typically emits yellow light in the wavelength range of 570 to 590 nm. It is characterized by a high luminous efficacy, often between 80 and 150 lumens per watt, depending on the efficiency of the phosphors used and the driver. Furthermore, it offers a long lifespan of up to 25,000 to 50,000 hours, depending on the operating temperature and conditions. Another important aspect is the generation of yellow light. This can only be produced with very insufficient color saturation by mixing lime / mint or green and red. Due to the types of phosphors used, the yellow light color is also not reproduced with the same narrowband frequency as in a pure yellow LED chip. In other words, a technical characteristic of a phosphor-converted LED is that it has a significantly wider half-width of its emission peak than a pure-color, non-phosphor-converted LED.This can be used to advantage in the present case to achieve a variable white point in combination with the other colored LEDs of the lighting device, each with a very high light quality.

[0015] The phosphor-converted yellow LED (PC Yellow) differs from the phosphor-converted amber LED (PC Amber) known in lighting technology, which has peak wavelengths in the range of 590 nm - 620 nm and therefore has overall emissions in the longer wavelength range than the PC Yellow LED of the device of the present invention.

[0016] In the context of the present invention, the term peak wavelength is used to refer to the emission wavelength of the LED with the highest intensity in the emission spectrum. A corresponding term is also peak value.

[0017] The full width at half maximum (FWHM) of a function with a peak is defined as the difference between the two argument values ​​for which the function values ​​have decreased to half the maximum; intuitively, the "width at half the height." Accordingly, in engineering, the FWHM is commonly referred to as "Full Width at Half Maximum." The FWHM thus indicates the width of any intensity distribution at half the maximum intensity. In particular, the FWHM is used to specify the width of spectral lines or as a measure of the narrowband nature of monochromatic light.

[0018] Within the scope of the present invention, the term "LED type" refers to LEDs with the same peak wavelength and half-width, whereby slight deviations in peak wavelength or half-width may occur, for example, due to batch or manufacturer changes, and these are nevertheless to be considered as belonging to the same type. For example, all LEDs of the PC Yellow type have essentially the same peak wavelength and half-width in the yellow region of the emission spectrum, all LEDs of the blue type have essentially the same peak wavelength and half-width in the blue region of the emission spectrum, and all LEDs of the cyan type have essentially the same peak wavelength and half-width in the cyan region of the emission spectrum, etc. The LEDs of one type may, but need not, be arranged in close proximity to each other in the lighting device.Individual LEDs or groups of LEDs of the same type can be arranged side by side or in close proximity to each other, while other individual LEDs or groups of LEDs of the same type are arranged at a comparatively greater distance from each other, for example at different edges of the substrate.

[0019] The device of the present invention therefore utilizes a combination of at least two different types of blue LEDs with a phosphor-converted yellow LED as described in more detail above. This makes it possible to utilize a correspondingly high proportion of green light for a high CRI, which is made possible by the lack of overlap between the two blue LEDs and the phosphor-converted yellow LED.

[0020] The LED lighting device of the present invention exhibits high spectral homogeneity in the generation of white light, can achieve a very good color rendering index (CRI), shows better generation of warm white light (< 4000 K) and a more efficient and uniform utilization of the individual LEDs, which also leads to more uniform aging processes, and enables better production of pure yellow light, especially in comparison to the generic luminaires which have a high overall proportion of a lime / mint LED.

[0021] In a preferred embodiment of the invention, the PC Yellow LED type provides at least 25% of the total light output of the lighting device and at least one type of blue LEDs is a deep blue / royal blue with a peak wavelength of 440-480 nm.

[0022] In another embodiment of the device according to the invention, both blue LED types together accounted for approximately 10% - 15% of the output in lumens.

[0023] For example, a lighting device of the present invention in one embodiment comprises 36 PC Yellow LEDs with a combined luminous efficacy of 18000 lm, combined with eight blue and 12 deep blue LEDs with a combined luminous efficacy of 2100 lm for a total luminous efficacy of 42000 lm, and wherein the device comprises 132 individual LEDs.

[0024] Alternatively, a lighting device of the present invention comprises 32 PC Yellow LEDs with a combined luminous efficacy of 16000 lm, combined with four blue and eight deep blue LEDs with a combined luminous efficacy of 1200lm for a total luminous efficacy of 40000 lm.

[0025] It is also possible to arrange 16 PC Yellow LEDs with 8000 lm luminous flux combined with four blue and four deep blue LEDs with a total luminous flux of 900 lm in a device with 66 LEDs and a luminous efficacy of 20500 lm.

[0026] In a preferred embodiment of the invention, the peak wavelength of the phosphor-converted yellow LED (PC Yellow) is in the range between 560 and 590 nm and / or the full width at half maximum (FWHM) is in a range between 40 nm and 200 nm, preferably between 60 nm and 160 nm, particularly preferably between 80 nm and 140 nm, and especially between 90 nm and 120 nm.

[0027] For example, PC Yellow LEDs can be used whose peak wavelength is at 570 nm, 575 nm, 590 nm, or similar values.

[0028] Within the scope of the present invention, the term peak wavelength is understood to be the emission wavelength with the highest intensity.

[0029] The peak wavelengths and half-widths of the peaks mentioned above are typical for phosphor-converted yellow (PC yellow) LEDs and, in combination with at least two different blue LED types whose peak wavelengths differ by at least 10 nm, lead to high spectral homogeneity in white light and simultaneously to improved production of white light with low CCT values, in particular to very good production of candlelight light, which also achieves very good results when recorded with digital cameras, which usually have a higher sensitivity to blue light components and therefore record such white light temperatures differently than the human eye.

[0030] A weakness of known lamps that can only mix green or lime and red to produce yellow or amber light is that the color is often not sufficiently saturated. This frequently leads to a very unnatural-looking yellow, particularly in reflection, and is completely overcome by the device according to the invention.

[0031] In a further embodiment of the device according to the invention, the luminous flux of the phosphor-converted yellow LED type (PC Yellow) accounts for at least 25% of the total luminous flux of the device in lumens. The proportion of the total luminous flux changes according to the parameters of the components used when the total luminous flux is expressed in watts.

[0032] This results in particularly good spectral homogeneity, especially of the generated white light. Furthermore, it eliminates the need for a separate lime / mint green LED in the device. This also leads to a very good balance in the power requirements of the individual LEDs, or LED types, when generating high-power white light, resulting in more uniform LED aging and consistent light quality throughout the device's entire lifespan.

[0033] According to a further embodiment of the invention, the power of the two blue LED types can be controlled independently of each other.

[0034] This results in clear advantages in color rendering. This is due to the greater variability of the blue components, especially when generating white light with a specific temperature (CCT value). The precision of the reproduction of the desired color temperature, also in relation to digital camera images, and thus the CRI value, is higher. It is also possible to recreate existing lighting situations, such as those that occur when using conventional incandescent lamps in combination with color filters. For example, it allows for the creation of a lighting atmosphere like that found under a blue sky or when simulating nighttime lighting conditions.

[0035] In a preferred embodiment of the device according to the invention, the two blue LED types are selected from the group consisting of Royal Blue, Blue, Cyan, and Indigo / Violet.

[0036] This has proven to be particularly advantageous with regard to the most efficient possible generation of cool white light with very good color rendering, especially of blue objects or costumes.

[0037] In a preferred embodiment of the device according to the invention, the full width at half maximum (FWHM) of the blue LEDs is at least 2 nm and at most 35 nm.

[0038] The aforementioned full width at half maximum (FWHM) are achieved by conventional blue LEDs with narrowband monochromatic emissions, for example, LEDs based on indium gallium nitride (InGaN) / gallium nitride (GaN). This ensures a high degree of variability in the blue component, particularly when generating high-quality white light, allowing for adaptation to specific stage, room, and / or camera requirements.

[0039] In a further embodiment of the device according to the invention, the peak wavelength of at least one of the blue LED types lies in the blue / royal blue range (440-480nm).

[0040] This ensures a high degree of variability in the blue light component, particularly in the generation of high-quality white light, allowing for adaptation to specific stage, room, and camera requirements. Additionally, the use of blue / royal blue enables the reproduction of light colors in the outer violet range of the color gamut, thus allowing the replication of certain lighting moods as achieved with arc lamps. At the same time, it also allows for a spectrally homogeneous simulation of daylight.

[0041] In a further embodiment of the device according to the invention, the device comprises at least one LED type with a peak wavelength in the red range (610-650nm).

[0042] In a further embodiment, the device comprises at least one LED type with a peak wavelength in the green range (500 - 570nm).

[0043] In a preferred embodiment, the device comprises at least one LED type with a peak wavelength in the amber range (590 - 620nm).

[0044] This can be a narrowband LED with the color amber, or a phosphor-converted LED with the color amber is used, which has a correspondingly larger half-width of the emission peak.

[0045] In a preferred embodiment, the device comprises at least one LED type with a peak wavelength in the deep red range (>650 nm).

[0046] The additional use of deep red LEDs not only enables a significantly improved reproduction of human skin tones, especially in recordings with digital cameras, but also, in conjunction with the PC yellow and blue LEDs available according to the invention, provides very good generation of white light with very warm color temperatures such as candlelight.

[0047] In a preferred embodiment, the device comprises LEDs with at least 5, preferably at least 6, particularly preferably at least 7 and particularly at least 8 different peak wavelengths.

[0048] In other words, in preferred embodiments, the device comprises LEDs of at least 5, preferably at least 6, particularly preferably at least 7 and particularly at least 8 different LED types.

[0049] This allows for better adaptability of the spectral reproduction, which is particularly important in the technical fields of stage, film, and event lighting technology. Each different LED, or rather each different LED type, has its own control channel and can therefore be individually controlled.

[0050] In a preferred embodiment, the device does not include LEDs with a peak wavelength in the lime / mint range. The lime / mint color space is defined in the CIE xy range by the coordinates (0.4, 0.6), (0.445, 0.555), (0.37, 0.425), (0.325, 0.45).

[0051] The use of phosphor-converted lime / mint LEDs (PC mint / lime) in particular always results in the green LEDs of the device not being activated when generating high-quality white light. Otherwise, the white light quality would be compromised, as PC mint / lime covers the spectral ranges of yellow and green. At the same time, however, a green LED type is always necessary to achieve the corresponding saturated colors in the gamut. This inevitably leads to a loss of light output relative to the lamp's total potential output. This loss ranges between 20-30% of the nominal total output.

[0052] This disadvantage is avoided by a lighting device according to the present invention, since the use of PC Yellow with two different blue LEDs makes it possible to also utilize the green LEDs in high-quality white light generation. In this way, the power loss with respect to the nominal total power of the device is reduced to only about 10% when all LEDs are used at maximum capacity.

[0053] The separation of the overlapping colors yellow and green also provides an additional control option and thus a more refined control of desired colors in the gamut at higher saturation.

[0054] The CIE color system allows colors to be described mathematically, and the dominant wavelength and purity of the color to be plotted in a diagram. As an objective color system, it does not require color samples and was designed as a basis for color measurements. Based on the color perception of the human eye, hue and saturation are encoded in a tongue-shaped chromaticity diagram, with each color point defined by the three parameters hue (T), saturation (S), and lightness (Y). Developed in 1931 by the Commission Internationale de l'Éclairage (CIE), it is one of the most widely used color ordering systems. To represent the three-dimensional color space perceived by the viewer more clearly (by color type), the two-dimensional CIE chromaticity diagram was developed. In this diagram, the third component, Z, for each point on the chromaticity diagram is calculated from the other two using the relationship x + y + z = 1.The horseshoe-shaped area of ​​possible colors in the CIE chromaticity diagram is plotted on a coordinate system from which the x and y components (of the CIE-standardized theoretical primary colors X (red), Y (green), and Z (blue)) of any given color P can be directly read. The z component can be calculated using the fundamental condition x + y + z = 1 (z = 1 - x - y).

[0055] Table 1 below shows an exemplary combination of LEDs with different peak wavelengths included in a lighting device of the present invention. However, manufacturing tolerances of the LEDs can cause these values ​​to vary considerably. Therefore, the table provides only guide values. Table 1 Color Peak wavelength [nm] FWHM [nm] Deep red 669 20 Red 638 20 PC Amber 597 80 PC Yellow 584 110 Green 522 30 Cyan 496 30 royal blue 450 20

[0056] The invention is explained in more detail with reference to the drawings and exemplary embodiments. The drawings are schematic representations and not to scale. The drawings do not limit the invention in any way. They show: Fig. 1 a diagram of a first embodiment of the lighting device according to the invention showing the individual spectral peaks of the different LED types, Fig. 2 a diagram for an exemplary white light spectrum of a color temperature of a lighting device according to the invention in a further exemplary embodiment, and Fig. 3 a diagram for a further exemplary white light spectrum of a different color temperature of a lighting device according to the invention in a further exemplary embodiment.

[0057] In Fig.Figure 1 shows an emission diagram with the corresponding wavelength as the x-axis and the respective emission intensity as the y-axis for the different LED types included in a lighting device according to the invention. The diagram shows, by way of example, the respective peak intensities at maximum power of the individual LED types. In the example shown, the lighting device according to the invention comprises eight different LED types, three of which are blue LED types. During operation of the lighting device, different relative intensities of the individual LED types will typically occur, depending on the requirements for color, rendering quality, and luminous flux. According to the invention, the illustrated embodiment of the device includes peaks from royal blue LEDs with a peak wavelength of approximately 450 nm and a full width at half maximum (FWHM) of approximately 20 nm, and from blue LEDs with a peak wavelength of approximately...470 nm and a full width at half maximum (FWHM) of approximately 25 nm, cyan LEDs with a peak wavelength of approximately 496 nm and a FWHM of approximately 30 nm, green LEDs with a peak wavelength of approximately 520 nm and a FWHM of approximately 30 nm, PC yellow LEDs with a peak wavelength of approximately 585 nm and a FWHM of approximately 110 nm, PC amber LEDs with a peak wavelength of approximately 600 nm and a FWHM of approximately 80 nm, red LEDs with a peak wavelength of approximately 640 nm and a FWHM of approximately 20 nm, and deep red LEDs with a peak wavelength of approximately 660 nm and a FWHM of approximately 20 nm. The device shown has no Lime / Mint type LEDs.

[0058] Fig.Figure 2 shows an exemplary emission diagram illustrating the respective intensities of the different LED types of a further embodiment of the device according to the invention when using a mixture of warm white light at 3200 K. In this embodiment, the device also comprises eight different LED types, which are selected similarly to the LED types of the device in Figure 2. Fig. 1. The resulting white light emission is shown as an intensity curve in black with a maximum in the red region. For comparison, the intensity curve of an ideal blackbody radiator at the same color temperature is also shown as a dashed line. Comparing the intensity curves for the device according to the invention and the ideal blackbody, it becomes apparent that the device according to the invention achieves high spectral homogeneity of the white light at a very high luminous efficacy.

[0059] Fig. 3 shows analogous to Fig.Figure 2 shows an intensity diagram illustrating the mixture of cool white light with a color temperature of 5600 K using a device of the present invention in a further embodiment. In this embodiment, the device also comprises eight different LED types, selected similarly to the LED types of the device in Figure 2. Fig. 1. With this mixed color, the maximum of the resulting spectrum lies in the blue range. In particular, it is necessary here to model the shape of the spectral emission curve from the different blue LEDs so that it corresponds to the natural daylight of a blue sky. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2019 120 298 A1

[0006]

Claims

[1] Lighting device for lighting stages, film and photo shoots or for light shows, comprising a substrate and a plurality of LEDs mounted on the substrate, wherein the device has LEDs with at least four different peak wavelengths, characterized by , that the plurality of LEDs comprises one type of phosphor-converted yellow LED (PC Yellow), wherein the peak wavelength of the phosphor-converted yellow LED (PC Yellow) is in the range between 560 and 590 nm, and comprises at least two types of blue LEDs, wherein the peak wavelengths of the two blue LED types are in the range between 390 nm and 510 nm and wherein the peak wavelengths of the two blue LED types differ by at least 10 nm. [2] Device according to claim 1, wherein the full width at half maximum (FWHM) of the phosphor-converted yellow (PC yellow) LEDs is in a range between 40 nm and 200 nm, preferably between 60 nm and 160 nm, particularly preferably between 80 nm and 140 nm, and especially between 90 nm and 120 nm. [3] Device according to one of claims 1 or 2, wherein the light output of the phosphor-converted yellow LEDs (PC Yellow) has a proportion of at least 25% of the total light output of the device. [4] Device according to one of claims 1 to 3, wherein the power of the two types of blue LEDs can be controlled independently of each other. [5] Device according to any one of claims 1 to 4, wherein the two blue LED types are selected from the group Royal Blue, Blue, Cyan, Indigo / Violet. [6] Device according to any one of claims 1 to 5, wherein the full width at half maximum (FWHM) of at least one of the blue LED types is at least 2 nm and at most 35 nm. [7] Device according to any one of claims 1 to 6, wherein the peak wavelength of at least one of the blue LED types is in the blue / royal blue range (440nm - 480nm). [8] Device according to one of the preceding claims, wherein the device comprises at least one LED type with a peak wavelength in the red range. [9] Device according to any of the preceding claims, wherein the device comprises at least one LED type with a peak wavelength in the green range. [10] Device according to one of the preceding claims, wherein the device comprises at least one LED type with a peak wavelength in the amber range. [11] Device according to one of the preceding claims, wherein the device comprises at least one LED type with a peak wavelength in the deep red range. [12] Device according to one of the preceding claims, wherein the device comprises LED types with at least 5, preferably at least 6, particularly preferably at least 7 and in particular at least 8 different peak wavelengths. [13] Device according to one of the preceding claims, wherein the device does not include LEDs with a color point in the CIE xy range Lime / Mint, which is defined by (0.4, 0.6), (0.445,0.555), (0.37,0.425), (0.325,0.45).

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