LED system with switchable light scenes

Abstract

LED system, featuring: - an LED driver circuit that supplies a series connection of several LED strings at one output, wherein the series connection has LED strings, preferably in the order mentioned: ◯ a first LED string with several cool white LEDs, ◯ a second LED string with several LEDs in the cyan spectrum, ◯ a third LED string with several warm white LEDs.

Description

[0001] The present invention relates to an LED system with switchable light scenes, in which the emission characteristics of the LED system can be selectively changed.

[0002] A particular application of the invention is the so-called melanopic light, which can be adjusted by switching the LED system according to the invention.

[0003] Several approaches are known in the art to achieve scene (color) changes of an LED light source. Multi-channel drivers are often used, with each channel electrically supplying a specific LED string.

[0004] Other approaches include setting a PWM duty cycle between two channels of a driver, or using different separate drivers.

[0005] These approaches all have their disadvantages. For example, multi-channel drivers or the use of multiple drivers are expensive. The PWM approach can produce visible light flicker.

[0006] The invention aims to provide a simplified LED system with changeable scenes of (color) characteristics.

[0007] This problem is solved by the features of the independent claims. The dependent claims further develop the central idea of ​​the invention in a particularly advantageous way.

[0008] According to a first aspect, an LED system is proposed which has an LED driver circuit which supplies at one output a series connection of several LED strings which may be arranged on one or different modules, wherein the series connection of the LED strings preferably has in the order now mentioned: - A first LED string with several cool white LEDs, - A second LED string with several LEDs in the cyan spectrum, and - A third LED string with several warm white LEDs.

[0009] The terms "cool white" and "warm white" can, for example, refer to white LEDs in the range of 3000-5000 K and 1200-2500 K respectively.

[0010] A cyan spectrum is understood to have a peak wavelength in the range of 440-520 nm, preferably 470-490 nm, more preferably 475-485 nm.

[0011] According to a further aspect of the invention, an LED system is proposed which includes an LED driver circuit that supplies a series connection of several LED strings at one output (the only output of the LED driver circuit). The series connection can, preferably in the following order: - A first LED string with several white LEDs, preferably in the range between 3000-5000 K, - A second LED string with several LEDs in the azure spectrum, and - A third LED string with one or more LEDs in the UV-B spectrum.

[0012] The LEDs in the azure spectrum may be LEDs with blue primary radiation, whose light is partially converted to higher wavelengths by phosphor conversion.

[0013] According to the invention, the second and / or the third LED string can be selectively activated / deactivated, thereby enabling a simple scene (color) change of the total light emission of the LED system. This color change can, for example, be controlled to replicate the natural melanopic progression of light.

[0014] For this purpose, a control circuit, preferably independent of the LED driver circuit, can be provided, which, for example, activates and deactivates the second and / or third LED string depending on a signal at a signal input of the control circuit. This signal can, for example, be a bus signal, such as a bus signal according to the DALI industry standard. In another embodiment, this signal can be the constant output signal of a microcontroller.

[0015] The activation / deactivation of the second and / or third LED string can be carried out, for example, by means of a preferably galvanically isolated switch that is arranged in parallel to the respective activating / deactivating LED string.

[0016] This switch can, for example, have an optocoupler input, which is used to switch a MOSFET to conduct in order to deactivate the associated LED string.

[0017] The first, second and / or third LED string may contain parallel series circuits of several LEDs.

[0018] The LED driver circuit is preferably dimmable by means of an external signal. This external signal can, for example, be fed to the control circuit mentioned above (which also activates or deactivates the LED strings) (again, for example, via a bus connection), whereby this control circuit then transmits corresponding signals to the LED driver circuit to dim the LED system.

[0019] One example application of the present invention is in the field of indirect lighting, in particular indirect ceiling or wall lighting, for example in the form of floor lamps, which thus have an LED system of the aforementioned type.

[0020] The invention further relates to the use of an LED system for indirect lighting to control a melanopic progression of the generated light spectrum.

[0021] An alternative application of the invention may also relate to combined lighting with direct and indirect light components or to purely direct lighting.

[0022] When the invention is applied to a direct light component, a higher visual contrast can be achieved using the invention.

[0023] When applying the invention to lighting with direct and indirect light components, for example only the indirect light component can be generated by the LED system according to the invention, while the direct light component is generated by an LED string with white LEDs with a color temperature between 3000 and 5000 K.

[0024] When applying the invention to lighting with direct and indirect light components, for example, only the indirect light component can be generated by the second and / or third LED string, while the direct light component is generated by the first LED string.

[0025] The LED system according to the invention can, for example, be used in a floor lamp, wherein the floor lamp has indirect and direct lighting. For example, the indirect lighting of the floor lamp can be generated by the second and / or third LED string, and the first LED string can be used for direct and / or indirect lighting.

[0026] Further features, advantages and properties of the present invention will now be explained in more detail on the basis of the figures in the accompanying drawings. - Fig. Figure 1 shows a first LED system according to the invention and - Fig. Figure 2 shows another embodiment of an LED system according to the invention.

[0027] In Fig. Figure 1, referenced as numeral 1, shows a general embodiment of an LED system according to the invention. This LED system 1 has terminals 2 and 3, which are connected to an output of an LED driver (LED driver circuit), which is not shown. The LED system comprises a first LED string 3, a second LED string 4, and a third LED string 5. These LED strings 3, 4, and 5 are connected in series.

[0028] Each of the aforementioned LED strings 3, 4 and 5 preferably has a parallel connection of several LED series sections.

[0029] The number of LEDs in the first LED string 3 is preferably greater than the number in the second LED string 4, and preferably the number of LEDs in the third LED string 5 is greater than the number in the second LED string 4.

[0030] The first LED string 3 preferably comprises essentially identical white LEDs with a color temperature between 3000 and 5000 K, preferably 3500 and 4500 K, more preferably between 3800 and 4200 K.

[0031] The second LED string 4 has LEDs that emit in the cyan blue range (wavelength 475nm to 485nm).

[0032] The third LED string 5 has white LEDs which preferably emit in a range between 1200 and 2400 K, more preferably between 1600 and 2000 K.

[0033] As from the Fig. As can be seen in Figure 1, the first LED string 3 is always in operation and therefore cannot be selectively activated or deactivated.

[0034] In contrast, the second LED string 4 and / or the third LED string 5 can be selectively activated or deactivated by means of bypass circuits 6 and 7, respectively. These bypass circuits 6 and 7 preferably have galvanically isolated switches that can be switched via signal inputs X7, X9, and X6, respectively. These bypass circuits 6 and 7 are preferably activated or deactivated by a control circuit (also not shown). The control circuit is preferably independent of the LED driver circuit. The control circuit can, for example, be a microcontroller that also has an external bus communication interface. Thus, an external signal (e.g., a bus signal) can be supplied to the control circuit to adjust the emission characteristics of the LED system 1. As mentioned, this is achieved relatively simply by selectively activating or deactivating certain LED strings (here 4 and / or 5).

[0035] Referring to Fig. Section 2 will now introduce another LED system according to the invention. Only the essential differences of this system 10 compared to the LED system 1 will be discussed. Fig. 1 will be shown.

[0036] Again, a series connection of several LED strings 11, 12, 13 is given.

[0037] This series connection of several (here three) LED strings is in turn supplied via terminals 2, 3, which are connected to the same output of an LED driver circuit.

[0038] The first LED strand 11 of Fig. 2 can be used with the LED system 3 of Fig. 1 corresponds.

[0039] In contrast, the second LED string 12 of this embodiment comprises LEDs that emit in the azure region. Such azure LEDs are offered, for example, by Nichia under the type NCSEE17AT. Besides a peak at approximately 460 nm, they exhibit a spectrum that continuously decreases down to approximately 650 nm.

[0040] The third LED string 13 consists of several or preferably only one UV-B LED (wavelength 280nm to 315nm).

[0041] In a manner comparable to the first embodiment of Fig. Here too, preferably galvanically isolated bypass circuits 6, 7 are provided, so that the second (Azur LED string) and the third (UV-B) LED string can be selectively activated or deactivated to change the produced light scene (light color).

[0042] The LED systems shown according to the invention can be part of an overhead lighting system, which thus illuminates the human eye from above, producing a melanopic effect. Indirect lighting, for example in the form of ceiling or wall lighting, is preferred.

Claims

[1] LED system comprising: - an LED driver circuit that supplies a series connection of several LED strings at one output, wherein the series connection has LED strings, preferably in the order mentioned: ◯ a first LED string with several cool white LEDs, ◯ a second LED string with several LEDs in the cyan spectrum, ◯ a third LED string with several warm white LEDs. [2] LED system comprising: - an LED driver circuit that supplies a series connection of several LED strings at one output, wherein the series connection has LED strings, preferably in the order mentioned: ◯ a first LED string with several white LEDs preferably in the range between 3000 and 5000 K, ◯ a second LED string with several LEDs in the azure spectrum, ◯ a third LED string with one or more LEDs in the UV-B spectrum. [3] LED system according to claim 2, wherein the Azure LEDs are blue LEDs with phosphor conversion. [4] LED system according to one of the preceding claims, wherein the second and / or the third LED string is / are selectively activatable / deactivatable. [5] LED system according to claim 4, further comprising a control circuit, preferably independent of the LED driver circuit, for activating and deactivating the second and / or third string depending on a signal at a signal input of the control circuit. [6] LED system according to claim 4 or 5, wherein the activation / deactivation is carried out by means of a preferably galvanically isolated switch in parallel to the respective string. [7] LED system according to claim 6, wherein the switch has an optocoupler. [8] LED system according to one of the preceding claims, wherein the first and / or the second and / or the third LED string each comprise parallel-connected series circuits of several LEDs. [9] LED system according to one of the preceding claims, wherein the LED driver circuit is preferably dimmable by means of an external signal. [10] Indirect lighting, in particular indirect ceiling lighting, comprising at least one LED system according to one of the preceding claims. [11] Direct lighting comprising at least one LED system according to any one of claims 1 to 9. [12] Use of an LED system according to any one of claims 1 to 9, an indirect lighting system according to claim 10 or a direct lighting system according to claim 11 for controlling a melanopic progression of the generated light spectrum.

Images