EP2254391A2 - Lighting assembly with at least one LED light source - Google Patents

Abstract

The device (1) has a detection unit (10) i.e. sensor, to detect light emitted by a light source (2) i.e. LED, and a control device (5) to control the light source based on information transmitted by the control device. The detection unit or a part of the detection unit is temporarily arranged in a light path (7) for detecting the light emitted by the light source, where the detection unit or the part of the detection unit is pivotable along the light path. A light guiding element i.e. mirror, is arranged in the light path.

Description

The present invention relates to a lighting arrangement according to the preamble of claim 1, which has at least one light source, in particular an LED, and detection means for detecting the light emitted by the light source. Furthermore, a control device for controlling the light source in dependence on the information transmitted by the detection means is provided. The application relates in particular to an LED luminaire which operates in accordance with the principle of the so-called feedback loop.

The use of LEDs or generally of light-emitting semiconductor elements in lighting technology has recently increased significantly, since meanwhile the light outputs that can be achieved with such light sources are sufficiently high even for larger lighting applications. An advantage of the LEDs here is their efficiency and the ability to achieve by appropriate mixture of different colors light in almost any desired color.

A problem of such LED lights, which are equipped with several different colored LEDs, however, is that these lights are not stable color without further control or regulation due to thermal influences or aging influences. Furthermore, production-related deviations in the light output can also be present. This means that without precise control in the driving of the LED, there is the danger that ultimately the color tone of the emitted light does not correspond to the user's wish.

Accordingly, it is known to measure the LED light individually or with regard to each color individually and then to carry out a control in the control of the LEDs that is tailored to the measurement result. In particular, the current supplied to the LEDs is set in such a way that ultimately the desired color location of the emitted (mixed) light can be stably maintained. The principle of such a regulation is, for example, in the WO 2004/057922 A1 or WO 2004/057923 A1 described.

The Fig. 5 and Fig. 6 show two views of a known from the prior art LED lamp, as sold by the applicant and which operates on this principle. On the one hand, this LED luminaire 101 has an elongated mounting module 102 which can be used, for example, in a busbar for mounting the luminaire 101 and which also has components for supplying power to the light sources (not shown) arranged in a cylindrical radiator housing 103. At the front end of the radiator housing 103, a light exit opening 104 is formed, via which the light of the differently colored LEDs arranged in the radiator housing 103 is emitted. Strictly speaking, the light output is distributed over the circumference of the light exit opening arranged distributed hexagonal segments 105. The center of the light exit opening 104, however, is formed opaque, since this is used to partially reflect the light emitted by the LEDs light. This then falls on a sensor which is located in the center of the LEDs. The information provided by the sensor is then used in the manner described above in the driving of the LEDs.

The in the Fig. 5 and Fig. 6 Although the solution shown has proven itself and allows effective and accurate control of the color of the light emitted by the lamp 101, the optical path, however, over which the light is returned to the sensor, is a loss path, ie, the light detected in this way not be used for the desired lighting purpose.

Basically, so as little light should be directed to the sensor, on the other hand, however, for an accurate color control is absolutely necessary that as far as the light of all light sources or LEDs falls on the sensor, so that a faulty or one of the other LEDs deviant behavior of a single LED can be reliably detected.

The present invention is accordingly an object of the invention to provide an improved over the prior art way, on the one hand to improve the detection or evaluation of the emitted light and on the other hand to open the possibility of using the light emitted by the light sources as effectively as possible for the lighting to be able to.

The object is achieved by a lighting arrangement having the features of one of the independent claims. Advantageous developments are the subject of the dependent claims.

The solution according to the invention is based on the idea of configuring the detection means or a part of the detection means in such a way that they can be temporarily introduced for detecting the light emitted by the light source into the beam path provided for the light emission of the arrangement.

According to a first aspect of the present invention, a lighting arrangement is accordingly proposed, which has at least one light source, in particular an LED, detection means for detecting the light emitted by the light source and a control device for controlling the light source in dependence on the information transmitted by the detection means, wherein According to the invention, the detection means or a part thereof for detecting the light emitted from the light source can be temporarily introduced into the light path of the arrangement provided for the beam path. In particular, it may be provided that the detection means or the corresponding part thereof is pivoted into the beam path or moved by means of a linear movement in the beam path.

An advantage of the solution according to the invention is therefore that the light detection means are arranged only temporarily in the beam path of the illumination arrangement, so do not interfere with the light output during normal operation. Only at regular time intervals for a short duration, the detection means or a part thereof are introduced into the beam path to detect the light emitted from the light source and to enable a corresponding light control accordingly. However, this period of time is so short that it is imperceptible to the human eye, so that ultimately the light output is not affected or the light emitted by the light source is more effectively used for illumination compared to the solutions known from the prior art can. The detection means introduced into the beam path or the part of the detection means introduced into the beam path can thereby completely cover the beam path. However, it would also be conceivable to introduce only one element, which covers a small area of the beam path. In this case, for example, a sensor could be introduced into the beam path. Alternatively, however, would also be possible to bring an optical element, in particular a mirror in the beam path, which temporarily decouples the light emitted from the light source or directed to a sensor.

In an alternative solution, the detection means are formed by a permanently located in the beam path optical element or the detection means have such an optical element, which is on the one hand in an operating mode almost completely transparent to the light emitted from the light source. Furthermore, however, the optical element can also be switched to a sensor mode in which it detects at least part of the light passing through and / or directs it to a sensor. In this variant, too, provision is therefore made for the light emission to take place substantially undisturbed, that is to say not influenced by the detection means. Only temporarily, a light detection or light extraction is initiated by switching the active optical element to allow control of the light output. Again, the light emitted by the light source can be used more effectively for illumination purposes.

Finally, a third solution according to the invention is to arrange the sensor for detecting the light emitted by the light source in a special way. In particular, in the event that the light source is formed by one or more LEDs, it is provided according to the invention to arrange and align the sensor so that it is directed to the edge region of the LED dies to the light detection based on the lateral light emission of the LED To do this. The sensor is preferably preceded by an optical element in the form of a hollow cylinder in order to minimize the influence of stray light. If an arrangement of a plurality of LEDs, in particular of different colors, is provided, then more sensors can be arranged in the vicinity of the LED dies or the sensor can be configured such that it circles around the LED arrangement and accordingly detects the light output of individual LEDs at different times.

In all three variants, the advantage is achieved that a better detection of the light emitted by the light sources is made possible, while at the same time the actual light output is disturbed by the lighting arrangement as little as possible. Accordingly, the light of the light sources can be better utilized, while at the same time the evaluation and control of the light output is improved.

Fig. 1

ein erstes Ausführungsbeispiel der erfindungsgemäßen Beleuchtungsanordnung mit einem in den Strahlengang schwenkbaren Sensor;

Fig. 2

ein zweites Ausführungsbeispiel der erfindungsgemäßen Beleuchtungsanordnung, bei dem ein Spiegel zum Erfassen des LED-Lichts in den Strahlengang gebracht wird;

Fig. 3a und 3b

ein drittes Ausführungsbeispiel einer erfindungsgemäßen Beleuchtungsanordnung mit einem aktiven optischen Element zur Lichterfassung;

Fig. 4

ein viertes Ausführungsbeispiel, bei dem das von den LED-Dies seitlich emittierte Licht erfasst wird und

Fig. 5 und 6

eine aus dem Stand der Technik bekannte Beleuchtungsanordnung.

The invention will be explained in more detail with reference to the accompanying drawings. Show it:

Fig. 1

a first embodiment of the illumination arrangement according to the invention with a pivotable in the beam path sensor;

Fig. 2

A second embodiment of the illumination arrangement according to the invention, in which a mirror for detecting the LED light is brought into the beam path;

Fig. 3a and 3b

A third embodiment of a lighting arrangement according to the invention with an active optical element for light detection;

Fig. 4

A fourth embodiment in which the light emitted from the LED side is detected light and

FIGS. 5 and 6

a known from the prior art lighting arrangement.

Fig. 1 shows a first embodiment of a generally provided with the reference numeral 1 lighting arrangement according to the invention, which may be, for example, part of an LED spotlight.

The lighting arrangement 1 according to the invention has as light sources a plurality of LEDs 2, which are arranged together on a circuit board 3. The LED chips are preferably mounted unhoused on the board 3 in order to achieve maximum light output. Preferably, these are differently colored LEDs 2, which in particular emit light in the colors red, green and blue. By a suitable control of the various LEDs 2 there is accordingly the possibility to achieve mixed light of a desired color. The control takes place with the aid of a control circuit 5, which supplies the LEDs 2 with a suitable current. In this case, the dimming of the LEDs 2 can take place by means of known methods, in particular by the fact that the LEDs are operated with a PWM signal.

The light emitted by the LEDs 2 light should be mixed on the one hand, on the other hand, however, be radiated within a certain limited angular range. For this purpose, a frusto-conical reflector 6 is used whose opening angle determines the size of the beam. At the same time, the reflector 6 also defines a beam path 7, represented by dashed lines, through which the light is emitted. At the output end of the truncated cone-shaped reflector 6, additional light-directing elements can be provided in order to influence the light output in the desired manner. Shown in the embodiment of Fig. 1 a transparent lens arrangement 8, wherein other optical elements, for example. Prisms or micro prism arrangements, lenses or the like could be used.

As with all known LED lights is also in the illustrated arrangement of Fig. 1 a problem in that the light output of the LEDs 2 depends on various factors. On the one hand, there are variations that can be attributed to the manufacture of the LEDs. On the other hand, the light output may also depend on the current operating temperature itself. In order to be able to permanently achieve a finely tuned light output, it is therefore already known to detect the light emitted by the LEDs 2 and to transmit the detected values to the control circuit 5 in order to make the most accurate possible adjustment of the color or color temperature within the scope of a control can.

Also in the lighting arrangement according to the invention, a corresponding control circuit 5 is provided, which is to be supplied with information about the light emitted by the LEDs 2. The peculiarity now consists in the design of the means for detecting the LED light, which are such that the light output of the illumination assembly 1 is as effective and undisturbed.

This is in the embodiment of Fig. 1 provided that a sensor 10, which is to detect the light emitted by the LEDs 2 light, not permanently but only temporarily in the beam path 7 of the arrangement 1 is arranged. The sensor 1 is in this case arranged on a lever 11 or a flap, which can be pivoted in such a way that the sensor 10 for detecting the LED light is located within the reflector 6 or the beam path 7. This position is in Fig. 1 illustrated, in which case the sensor 10 is preferably arranged centrally above the LEDs 2. In a rest state, however, the flap 11 is pivoted downwards, such that the sensor 10 is completely outside the beam path 7.

The sensor 10, the data of which then - as shown schematically - the control circuit 5 are transmitted, so only at regular intervals in the beam path 7 is pivoted to briefly detect the light emitted by the LEDs 2 light. For the rest of the time, however, the light output can be undisturbed, since the beam path 7 is completely free of the sensor 10 or other means for light detection. It would be conceivable for the realization of this embodiment, a folding mechanism, as it is known for example from SLR cameras. In this case, the sensor 10 is pivoted into the beam path 7 only for a very short period of time, which is preferably in the millisecond range, and this process can not be recognized by the human eye. For a viewer of the lamp results over time the impression of a completely uniform and continuous light output, despite all the reliable light from the LEDs 2 detected and accordingly a precisely tuned control of the light output is achieved.

Fig. 2 shows a second embodiment in which comparable elements are provided with the same reference numerals. Again, a plurality of LEDs 2 are arranged on a circuit board 3, wherein the light of the LEDs 2 is emitted by means of a frusto-conical reflector 6.

A first special feature consists in the fact that the sensor 10 for detecting the LED light is also arranged on the circuit board 3. In order to be able to detect the light emitted by the LEDs 2, a mirror 20 is introduced into the beam path 7, which throws the light of the LEDs 2 back onto the sensor 10. Shown in Fig. 2 only two LEDs, although preferably again several, especially different colored LEDs can be used. The mirror 20 is designed slightly curved in the present case in order to bundle as much light on the sensor 10, which in turn improves the quality of light detection and thus the light control. Again, however, it is provided that the mirror 20 is not permanently disposed within the beam path 7, but is introduced only temporarily in this area, now a horizontal linear movement of the mirror 20 is provided, the mirror 20 thus from a region outside the reflector. 6 is inserted into this. This process can take only a few milliseconds, so that in turn an undisturbed for an observer light output is achieved with very precise control.

It should be noted that it would also be conceivable that the mirror 20 completely covers the beam path 7 in the position used for light detection. Furthermore, the mirror 20 could, as in the embodiment of Fig. 1 be pivoted in the beam path or the sensor in the embodiment of Fig. 1 be introduced by means of a linear movement in the beam path 7.

A third embodiment is in the Fig. 3a and 3b shown. Again, the same elements are provided with the same reference numerals, that is, the light of several - especially different colored - LEDs 2 is emitted via a reflector 6. In the present case, the upper side of the reflector 6 is now closed with an active optical element 30. This optical element 30 can switch between two different states, which in the Fig. 3a and 3b are shown.

In a normal operating condition, which is in Fig. 3a is shown, the optical element 30 is preferably completely transparent to the LED light and preferably does not affect the light output. It would also be conceivable to apply a prism structure or lens arrangement to the top side or the side of the element 30 facing away from the LEDs 2 in order to influence the light output in the desired manner. It is essential, however, that in the operating state, the LED light is emitted almost completely to the outside. By an appropriate control, which is preferably also carried out by the control circuit 5, however, now the optical element 30 can be switched to a sensor mode, the in Fig. 3b is shown. Here now serves the optical element 30 of the light detection, since it detects the LED light and forwards to the sensor 10. In this case, the optical element 30 is completely light-absorbing or at least partially transparent, so that in any case at least part of the LED light can be detected and evaluated. Again, it is envisaged that the light detection is made repeatedly at short intervals to achieve a continuous light output for a viewer.

In the embodiment of the Fig. 3a and 3b the light is absorbed by the optical element 30. However, it would also be conceivable to use an optical element which on the one hand is translucent and, on the other hand, reflective. As in the embodiment of Fig. 2 could then be reflected in the sensor mode with the aid of the optical element, the light on a, for example. Again arranged on the board 3 sensor. In this variant, too, the advantage is that during normal operation the entire LED light is radiated towards the outside, whereas in the short measuring phases almost the entire LED light can be used for the evaluation.

Fig. 4 Finally, shows a fourth embodiment of a lighting arrangement 1 according to the invention, in which in turn the same elements are provided with the same reference numerals.

The peculiarity now consists in the arrangement and configuration of the sensor 10 for detecting the LED light, which is now completely and permanently disposed outside of the light path provided for the light path 7. In particular, the sensor 10 is disposed on the peripheral portion of the LED array and oriented so as to face the edge area of the LED chips. In this case, the light emitted via the side surfaces of the LED chips is detected, which in any case can not be used for illumination purposes. Accordingly, on the one hand a very precise light detection is achieved, on the other hand, the actual light output of Lighting arrangement 1 not impaired. Preferably, the sensor 10 is preceded by a tube 12 to minimize the influence of stray light. Further, as shown - several, especially different colored LEDs present, it can further be provided that a plurality of sensors 10 are arranged on the circumference of the LED array, which are each aligned with a specific LED of a particular color. The information of these multiple sensors are then in turn transmitted to the control circuit 5. Alternatively, it would be conceivable that the sensor 10 encircles the LED array, where it is then aligned here at different times on each different LEDs. Respective sensor signals are transmitted to the control unit 5 at the time of optimal alignment with an LED so that all LEDs can be detected over time.

Finally, with the lighting arrangements according to the invention, a very accurate detection of the LED light and, correspondingly, a fine regulation of the light output can take place. At the same time, however, it is ensured that the regulation hardly or not at all influences the actual light output for illumination purposes and accordingly an optimized light output can be achieved.

Claims (12)

Lighting arrangement (1) with At least one light source (2), in particular an LED, • detection means (10, 20) for detecting the light emitted from the light source (2) and A control device (5) for activating the light source (2) as a function of information transmitted by the detection means (10), characterized,
in that the detection means (10, 20) or a part thereof for detecting the light emitted by the light source (2) can be temporarily introduced into the beam path (7) provided for the light emission of the arrangement. Lighting arrangement according to claim 1,
characterized,
that the detection means (10, 20) or a part thereof in the beam path (7) are pivotable. Lighting arrangement according to claim 1,
characterized,
that the detection means (10, 20) or a part thereof by means of a linear motion in the beam path (7) are movable. Lighting arrangement according to one of the preceding claims,
characterized,
in that the detection means (10, 20) introduced into the beam path (7) or the part of the detection means (10, 20) introduced into the beam path (7) completely cover the beam path (7). Lighting arrangement according to one of the preceding claims,
characterized,
that a sensor (10) in the beam path (7) can be inserted. Lighting arrangement according to one of claims 1 to 4,
characterized,
that a light-guiding element (20), in particular a mirror in the beam path (7) can be introduced, the position located in the in the beam path (7) the light to a sensor (10) deflected. Lighting arrangement (1) with At least one light source (2), in particular an LED, • detection means (10, 20) for detecting the light emitted from the light source (2) and A control device (5) for activating the light source (2) as a function of information transmitted by the detection means (10), characterized,
in that the detection means comprise an optical element (30) permanently located in the beam path (7), which is transparent in an operating mode and switchable to a sensor mode in which the optical element (30) detects and / or detects at least part of the transmitted light on a sensor (10) directs. Lighting arrangement (1) with At least one light source (2) in the form of an LED, • detection means (10, 20) for detecting the light emitted from the light source (2) and A control device (5) for activating the light source (2) as a function of information transmitted by the detection means (10), characterized,
in that the detection means (10, 20) are aligned with an edge region of the LED chip. Lighting arrangement according to claim 8,
characterized,
in that the illumination arrangement has a plurality of LEDs, wherein the detection means (10, 20) have a plurality of sensors (10) which are each aligned with a single LED. Lighting arrangement according to claim 8,
characterized,
in that the illumination arrangement has a plurality of LEDs, wherein the detection means (10, 20) comprise a sensor (10) which is arranged to be movable in such a way that it is aligned with a different LED at different times. Lighting arrangement according to claim 9 or 10,
characterized,
in that a respective tube is arranged upstream of the sensor (10) or the sensors (10). Lighting arrangement according to one of the preceding claims,
characterized,
that this has a plurality of different colored LEDs (2).

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