EP3407681B1 - Method and device for performing a functional check for an illuminant for lighting or indicating purposes - Google Patents

Description

The present invention relates to a method and a device for carrying out a functional test of a lamp of a luminaire for lighting or display purposes. The lamp comprises at least two lamps that can be switched to a first or a second state. In the first state, the illuminants emit a first light output specific to the illuminant. In the second state, they emit a specific second light output. The first light output is greater than the second light output. The lamps can preferably be LEDs.

The use of light-emitting diodes (LEDs) as illuminants for safety-related tasks, for example in vehicles, is becoming increasingly important. In particular, vehicles with autonomous or semi-autonomous states require, for example, an illuminant or LED diagnosis capability in the case of optical status displays (for example LED light strips). At least the states "LED lights up" or "LED does not light up" should be able to be recognized in order to avoid failures Diagnosing and recognizing LEDs so that the user or driver can be informed and the affected LEDs can be replaced.

However, only methods for indirect diagnosis are known from the prior art which evaluate the voltage drop across the LEDs or the current or energy consumption of the LEDs. For this, intelligent drivers are used, which are expensive. The diagnosis is always made in cooperation with such a driver, but only indirectly via a voltage / current evaluation.

DE 100 18 760 A1 discloses a circuit for monitoring the function of a light emitting diode.

• DE 10 2015 008 110 A1 ,
• DE 10 2015 017 086.4 (noch unveröffentlicht),
• DE 10 2015 008 109 A1 ,
• DE 10 2015 017 087.2 (noch unveröffentlicht),
• DE 10 2016 105 516 B3 ,
• DE 10 2016 1055 17B3 ,
• DE 10 2016 119 584.7 (noch unveröffentlicht),
• US2008 0 204 029 A1 ,
• US 2007 0 159 750 A1 ,
• EP 0 955 619 A1 ,
• DE 10 2011 120 781 A1 ,
• DE 11 2009 005 227 T5 ,
• DE 10 2014 107 947 A1 ,
• US 2012 0 200 296 A1 ,
• US 2006 0 170 287 A1 ,
• US 2007 0 159 750 A1

For example, methods and devices for monitoring electrical or thermal parameters of light-emitting diodes (LED) and chains of light-emitting diodes (light-emitting diode strips, LED strips) are known from the following documents:

• DE 10 2015 008 110 A1 .
• DE 10 2015 017 086.4 (still unpublished),
• DE 10 2015 008 109 A1 .
• DE 10 2015 017 087.2 (still unpublished),
• DE 10 2016 105 516 B3 .
• DE 10 2016 1055 17B3 .
• DE 10 2016 119 584.7 (still unpublished),
• US2008204209A1 .
• US 2007 0 159 750 A1 .
• EP 0 955 619 A1 .
• DE 10 2011 120 781 A1 .
• DE 11 2009 005 227 T5 .
• DE 10 2014 107 947 A1 .
• US 2012 0 200 296 A1 .
• US 2006 0 170 287 A1 .
• US 2007 0 159 750 A1

A disadvantage of the prior art is that the actual function of the light emission or the light emission of the lamps is not checked.

There is therefore a need for an improved and more direct diagnostic option.

The object of the present invention is therefore to propose an improved method for precisely checking the function of a lamp, in particular an LED, which in particular avoids the disadvantages known from the prior art.

This object is achieved by a method having the features of claim 1 and an apparatus having the features of claim 12.

The method according to the invention for carrying out a functional test of a lamp of a lamp for lighting or display purposes requires at least two lamps. During the functional test, the functional state of a lamp is determined, a possible functional state being a defect and the state thus meaning "defective". Another functional state reflects the correct functioning of the lamp and is referred to as "intact". The functional state thus allows a statement to be made about the illuminant, in particular about its luminous emissivity.

The illuminants required for the method can be wired in such a way that they emit a specific first light output in a first state and emit a specific second light output in a second state. The first light output is greater than the second light output. For the purposes of the invention, “specific light output” means a light output that is related to the respective illuminant. The light output can therefore depend on the type of illuminant and can be different for each illuminant. In a special embodiment in which LEDs are used as illuminants, the specific light output can depend on the respective LEDs or illuminants, for example depending on whether it is a blue, red or green LED.

According to the invention, the first illuminant is switched to the first state. The second illuminant is switched to the second state. In a further method step, a measured value of an electrical parameter caused in the second illuminant is measured, the measured value being caused by the first light output of the first illuminant. The measured value is evaluated so that a functional state can be determined. Here, the functional state of one of the two lamps is detected, which allows a statement about the light emissivity of the lamp.

The invention is explained below with the aid of LEDs, which are described as representative of illuminants. However, this does not represent a limitation of the invention in its generality or to LEDs as illuminants, unless something to the contrary is explicitly described.

In the context of the invention, it was recognized that in the event of a fault or defect in a light source, in particular an LED, which relates to the radiation behavior, that is to say the emission, there is also no measurable effect on absorption. For example, an LED that does not emit any light output cannot receive any light output; in any case, no photo current and / or no voltage can be measured at the LED. This principle, which was first established in experiments, could be theoretically supported and derived from Einstein's law, according to which the emission coefficient is equal to the absorption coefficient.

In a special embodiment of the method according to the invention, a third illuminant is used, which can also be switched to a first or second state in which a first or second light output is emitted. The first light output is greater than the second light output.

The third illuminant is also switched to the second state, in which a specific second light output is emitted. In a further step, a measured value of an electrical parameter is determined, which is caused by the first light output emitted by the first illuminant in the third illuminant. This measured value, referred to as the second measured value, is evaluated, whereby it can optionally be related to the (first) measured measured value of the second illuminant. From the second measured value of the third illuminant and the measured value of the first illuminant, conclusions can be drawn about the functional state or a possible error of one of the three illuminants.

In a preferred embodiment of the method, a defect of the first illuminant is recognized if the measured values of the second illuminant and / or the third illuminant lie below a threshold value specific for the respective illuminant. The threshold value is preferably set such that a measured value that lies above the threshold value represents an intact state of the illuminant. A light output radiated in from outside is recognized in the respective illuminant, since the measured value lies above the threshold value.

If the first illuminant radiates with the first light output into the other illuminant (s), the measured value detected in the respective illuminants remaining below the threshold value, it can be assumed that the first illuminant has not emitted sufficient light output. It can thus be concluded that the first illuminant is defective and in particular that the first illuminant is faulty or defective.

In a preferred embodiment with a total of at least three lamps, the functional state of the second lamp, which is switched to the second state, can be determined. If the measured value measured in the second illuminant lies below the specific threshold value and at the same time the measured value measured in the third illuminant lies above the specific threshold value, there is a defect in the second illuminant. The third illuminant has recognized the emitted light output of the first illuminant because the measured value lies above the threshold value. At the same time, however, the second illuminant receives no or too little light output, so that the measured value remains below the threshold value. A malfunction of the second illuminant can be recognized from this.

In a special embodiment of the method, an intact behavior and complete functionality of the first illuminant is recognized if the measured value is above the respective specific threshold value in the two other illuminants which are switched to the second state, that is to say the second and third illuminants. The second and third illuminants recognize the emitted light emission from the first illuminant. At the same time, the intact function and emissivity of the second and third lamps are detected because they absorb enough light.

The functional state of one of the two lamps switched into the second state is recognized as intact if the difference between the measured value measured and the associated specific threshold value has the same sign for both lamps. Either the measured value lies above the respective threshold value, so that the light emission emitted by the first illuminant is detected, or both illuminants (second and third illuminant) do not detect any light emission, the two illuminants being classified as intact. If the measured values of both lamps are below the threshold value, it can be concluded that the emitting lamp or LED is faulty.

In a preferred embodiment of the method, the second light output of the lamps is so low that there is no or significantly lower light emission than the first light output of the lamps. The second light output of each lamp is preferably lower than the first light output of any lamp. A significantly lower light output or significantly lower light emission in the second state means in Within the scope of the invention, that a light output radiated by the light emission of a lamp in the first state into a lamp is greater than the (significantly lower) light output of the received lamp, in particular an LED. The light output received in a light source which is switched in the second state and emits a second light output is preferably so much greater that a predetermined signal-to-noise ratio is achieved, for example that the received light output is larger, preferably significant and distinguishable in practice is greater than the emitted light output of the illuminant in question. In this case, it can be guaranteed that a received light output is detected and recognized as such.

In a special embodiment of the method, LEDs are used as illuminants. The LEDs used particularly preferably emit all different colors. For example, the first LED emits a blue color, the second LED a green and the third LED a red color. The LEDs preferably have different focal wavelengths, the focal wavelength being the wavelength in the wavelength spectrum at which an intensity maximum of the corresponding LED or the corresponding light source occurs.

The electrical parameter measured in the method is preferably a photo voltage or a photo current. The photo voltage is the voltage applied to the LED, which is generated by a photo current that arises due to the received emission of light. In the case of an LED, the photo voltage is sometimes also called LED voltage. The product of photo current and photo voltage corresponds to the light energy converted into electrical energy in the irradiated LED or illuminant. The energy is preferably measured with an external impressed voltage of 0 volt (0 V) as pure photo current or with an external impressed current of 0 ampere (0 A) as pure photo voltage. The person skilled in the art can also determine the energy generated in other operating points, the determination being more complex is. Photo current and photo voltage can be used as a measure of the light output that shines on a lamp or an LED.

In a preferred embodiment of the method, the lamp has two groups of lamps, each group of lamps comprising at least one lamp and one lamp of the first group of lamps being switched to the first state and one lamp of the second group of lamps being switched to the second state. The functional state is therefore detected between two groups of lamps.

In a preferred embodiment, a lamp is used in which at least two groups of lamps each comprise three lamps. A lamp of the first group of lamps is switched to the first state, while a lamp of the second group of lamps is switched to the second state. Two lamps of the second group of lamps are preferably switched to the second state; all lamps of the second group of lamps are particularly preferably switched to the second state. While the first group of lamps emits light, at least one of the lamps in the first group of lamps, the light emissions are measured in the second group of lamps, preferably at least two lamps receiving the emitted light, so that a measured value can be measured. No light is preferably emitted in the second state, so that the lamps of the second group of lamps are switched off.

The object on which the invention is based is also achieved by a device for carrying out a functional test. According to the invention, the device has at least two lamps, a control unit, a measuring unit, an evaluation unit and two switches. The two switches can be switched by the control unit, so they are switchable. The switches can assume several states and can be replaced or implemented by technical equivalents. One illuminant each can be switched to a first state or a second state by means of one of the switches. Possibly more states can be provided. A specific light output is emitted in each of the two (or more) states, the light output in the first state being greater than that in the second state. The list service can also be zero in one state. The control unit is designed and set up to switch the first illuminant into the first state and the second illuminant into the second state. The measuring unit detects a measured value of an electrical parameter, in particular a current or a voltage, on the second illuminant. The electrical parameter is caused by the first light output of the first illuminant, which is emitted and received in the second illuminant. The evaluation unit evaluates the measured value and detects a functional state or fault state of one of the lamps, as already described above.

In a special embodiment of the device according to the invention, the control unit, the measuring unit and / or the evaluation unit are integrated in a microcontroller (μcontroller) or in a computer.

The illuminants used are particularly preferably light-emitting diodes, LEDs. The device also preferably comprises an analog-digital converter in order to make the measured values available to the microcontroller. In a further particular embodiment, the device comprises a multiplexer in order to process several measured values.

In automotive applications, control processors (µcontrollers) which control the groups of lamps are equipped with an analog-to-digital converter in order to be able to record various parameters of a lighting device. These analog-to-digital converters of the control processors can be used, for example, via a multiplexer to measure the photo voltage or the photo current or, more generally, the energy generated by the irradiation in the irradiated LED (lamp) of the lamp group and one To determine the measured value. Since it is generally known which intensity is emitted by the emitting LED (LED in the first state with the first light output), the measured value determined in this way can be determined using a (specific) threshold value are compared. The first state is preferably referred to as "on", in which light output is emitted, and the second state is referred to as "off", in which the illuminant is switched off and no light output is emitted. A distinction is preferably made only between on and off in the emitted intensity.

If the measured value is below the threshold value, then either the emitting LED emits too little light output or the irradiated LED generates too little photo voltage or photo current. In this respect, it can already be assumed from this that the lamp group as such has at least one of these defects.

A lamp group in the sense of the invention generally comprises more than one lamp or more than one LED. Preferably, but not necessarily, a group of lamps for applying the proposed method comprises a red, a green and a blue LED or similar combinations of complementary colors. In this case, by cyclically interchanging the radiant and the irradiated LEDs of such a group of illuminants in the event of a single fault, it can be found out which LED is actually defective. This enables direct diagnosis of the light emission of one (or all) LED in the case of groups of lamps made of LEDs.

In contrast, the state of the art only evaluates the position of the electrical operating parameters within predetermined tolerance ranges. It is not checked whether the lamps actually emit light. The proposed method thus enables a direct check of the light radiation instead of an indirect conclusion for such light radiation.

Different groups of lamps of a larger lighting device can also radiate among themselves. The method proposed here is therefore also suitable for testing light strips with suitable light sources which are arranged along the light strip.

The light sources on the light strip are preferably equally spaced. With the same lamps, the same optical couplings between the individual lamps preferably occur in the case of linear, planar laying, which preferably enables the method according to the invention to be used in this case.

If the light sources are not equally spaced along such a light strip, then the use of the proposed method preferably requires a known distance or a known optical coupling between the light sources. This previous knowledge can be determined on the basis of the design on a prototype in the form of suitable coupling parameters. With identical light strips, similar coupling factors with certain tolerances can be expected. A suitable prior knowledge can preferably also be obtained by simulation or calculation of the mutual irradiation intensity. If the light strip is not laid planar, this has the same effect as different distances between the illuminants of the light strip.

The method according to the invention is preferably suitable for testing luminous mats, that is to say two-dimensional arrangements of illuminants. In this case, the lamps are preferably arranged in the form of a two-dimensional, particularly preferably regular, grid. A cubic or hexagonal arrangement of the lamps is particularly preferred. In the event of deviations from such regular structures, previous knowledge can be obtained by simulation or experiments with prototypes, which provide the further (necessary) parameters for an improved calculation of the optical coupling.

An objection typically raised by experts is that the groups of illuminants generally have LEDs of different colors in order to be able to represent all colors recognizable by humans in the color space as RGB color. Therefore, in this opinion, it should certainly be possible to generate a photo current with a short-wave LED, for example a blue LED, in a long-wave LED, for example a red LED, because the band gap of the long-wave LED, for example the red LED, is smaller than the photon energy of the photons emitted by the short-wave LED, i.e. the blue LED. Conversely, however, according to this expert opinion, experts expect that it is simply not possible to use a long-wave LED, e.g. a red LED, in a short-wave LED, e.g. a blue LED, to produce a safely measurable photo current or a reliably measurable photo voltage , since the band gap of the short-wave LED, for example the blue LED, is greater than the photon energy of the photons emitted by the long-wave LED, for example the red LED.

In the context of the invention, it was recognized that this fact does not stand in the way of a diagnosis, since a sufficient state detection is possible via a mutual combinatorics. Here, the fact is used that the emission coefficient is always the same as the absorption coefficient and thus, if there is a defect in the emission, there is no measurable electrical effect in the absorption.

• Die blaue LED wird bestromt und strahlt blaues Licht ab. Die rote LED und die grüne LED werden bevorzugt nicht bestromt.
• Es wird ein erster Messwert für die Fotospannung und/oder den Fotostrom der roten LED ermittelt. Beispielsweise kann zusätzlich die Fotoleistung der roten LED aus dem Produkt von Fotospannung und Fotostrom ermittelt werden.
• Es wird ebenso ein zweiter Messwert für die grüne LED ermittelt und optional die Fotoleistung.
• Der erste Messwert wird mit einem ersten Schwellwert für den ersten Messwert bei Bestrahlung der roten LED durch die blauen LED verglichen und bevorzugt ein erster Vergleichswert ermittelt.
• Der zweite Messwert wird mit einem zweiten Schwellwert für den zweiten Messwert bei Bestrahlung der grünen LED durch die blauen LED verglichen und bevorzugt ein zweiter Vergleichswert ermittelt.

The method according to the invention can preferably look as follows when measuring RGB illuminant groups with a blue LED that emits blue light, with a green LED that emits green light, and with a red LED that emits red light.

• The blue LED is energized and emits blue light. The red LED and the green LED are preferably not energized.
• A first measured value for the photo voltage and / or the photo current of the red LED is determined. For example, the photo output of the red LED can also be determined from the product of photo voltage and photo current.
• A second measured value for the green LED is also determined and, optionally, the photo power.
• The first measured value is compared with a first threshold value for the first measured value when the red LED is irradiated by the blue LED, and preferably a first comparison value is determined.
• The second measured value is compared with a second threshold value for the second measured value when the green LED is irradiated by the blue LED, and preferably a second comparison value is determined.

• Der erste Vergleichswert nimmt bevorzugt einen ersten Zustand an, wenn der erste Messwert unterhalb des ersten Schwellwerts (für den ersten Messwert bei Bestrahlung der roten LED durch die blauen LED) liegt, und einen zweiten Zustand an, wenn der erste Messwert oberhalb des ersten Schwellwerts liegt. Der erste Zustand entspricht also dem Fall, dass die blaue LED strahlt und die rote LED das Licht der blauen LED empfängt und in einen Fotostrom bzw. eine Fotospannung umwandelt. Der zweite Zustand entspricht dann dem Fall, dass zumindest einer dieser beiden Vorgänge nicht stattfindet.
• Der zweite Vergleichswert nimmt bevorzugt einen ersten Zustand an, wenn der zweite Messwert unterhalb des zweiten Schwellwerts (für den zweiten Messwert bei Bestrahlung der grünen LED durch die blauen LED) liegt, und einen zweiten Zustand an, wenn der zweite Messwert oberhalb des zweiten Schwellwerts für den zweiten Messwert liegt. Der erste Zustand entspricht also dem Fall, dass die blaue LED strahlt und die grüne LED das Licht der blauen LED empfängt und in einen Fotostrom bzw. eine Fotospannung umwandelt. Der zweite Zustand entspricht dem Fall, dass zumindest einer dieser beiden Vorgänge nicht stattfindet.
• Ein weiterer Schritt umfasst das Ermitteln des Zustands der LEDs aus dem ersten Vergleichswert und dem zweiten Vergleichswert.
• Sind beide Vergleichswerte im zweiten Zustand, so strahlt die blaue LED und das Licht wird von der roten LED und von der grünen LED empfangen. Dies lässt darauf schließen, dass die blaue LED korrekt arbeitet und dass die grüne LED korrekt arbeitet und dass die rote LED korrekt arbeitet.
• Ist der erste Vergleichswert im zweiten Zustand und der zweite Vergleichswert im ersten Zustand, so strahlt die blaue LED und das Licht der blauen LED wird von der roten LED empfangen und von der grünen LED nicht empfangen. Dies lässt darauf schließen, dass die blaue und die rote LED korrekt arbeiten und dass die grüne LED nicht korrekt arbeitet.
• Ist der erste Vergleichswert im ersten Zustand und der zweite Vergleichswert im zweiten Zustand, so strahlt die blaue LED und das Licht der blauen LED wird von der roten LED nicht empfangen und von der grünen LED empfangen. Dies lässt darauf schließen, dass die blaue und grüne LED korrekt arbeiten und dass die rote LED nicht korrekt arbeitet.
• Sind beide Vergleichswerte im ersten Zustand, so strahlt die blaue LED wahrscheinlich nicht und das Licht der blauen LED wird von keiner der anderen LEDs empfangen. Dies lässt darauf schließen, dass entweder als erste Möglichkeit die blaue LED nicht korrekt arbeitet oder dass als zweite Möglichkeit die grüne LED und die rote LED nicht korrekt arbeiten.

The other preferred steps use the two comparison values for evaluation and analysis. Of course, the evaluation and analysis can only be carried out with the measured value and threshold value, i.e. without a direct comparison value, as described above.

• The first comparison value preferably assumes a first state when the first measured value lies below the first threshold value (for the first measured value when the red LED is irradiated by the blue LED), and a second state when the first measured value lies above the first threshold value , The first state corresponds to the case in which the blue LED shines and the red LED receives the light from the blue LED and converts it into a photo current or photo voltage. The second state then corresponds to the case that at least one of these two processes does not take place.
• The second comparison value preferably assumes a first state if the second measured value lies below the second threshold value (for the second measured value when the green LED is irradiated by the blue LED), and a second state if the second measured value lies above the second threshold value for the second reading. The first state thus corresponds to the case where the blue LED shines and the green LED receives the light from the blue LED and converts it into a photo current or photo voltage. The second state corresponds to the case that at least one of these two processes does not take place.
• A further step comprises determining the state of the LEDs from the first comparison value and the second comparison value.
• If both comparison values are in the second state, the blue LED shines and the light is received by the red LED and the green LED. This suggests that the blue LED is working correctly and that the green LED is working correctly and that the red LED is working correctly.
• If the first comparison value is in the second state and the second comparison value is in the first state, the blue LED shines and the light of the blue LED is received by the red LED and not received by the green LED. This suggests that the blue and red LEDs are working correctly and that the green LED is not working correctly.
• If the first comparison value is in the first state and the second comparison value is in the second state, the blue LED shines and the light of the blue LED is not received by the red LED and received by the green LED. This suggests that the blue and green LEDs are working correctly and that the red LED is not working correctly.
• If both comparison values are in the first state, the blue LED is probably not shining and the light of the blue LED is not being received by any of the other LEDs. This suggests that either the blue LED does not work correctly as the first option or that the green LED and the red LED do not work correctly as a second option.

This measurement can be carried out in an analog manner with the green LED as the transmitter and the red LED as the only receiver in order to obtain further information. Of course, more colors and / or LEDs can also be used.

On the other hand, a clear diagnosis with assignment of the exact error to a specific lamp (here LEDs) is often in real applications not mandatory. As a rule, a statement about a defect in the lighting group itself is sufficient.

1. a) Innerhalb einer Leuchtmittelgruppe durch Absorption zwischen benachbarten LEDs dieser Leuchtmittelgruppe oder
2. b) Leuchtmittelgruppen übergreifend, wobei die Lichtemission einer LED einer ersten Leuchtmittelgruppe mittels einer LED einer benachbarten Leuchtmittelgruppe detektiert werden kann.

In a preferred embodiment of the method according to the invention, the light detection for diagnosis in the presence of several groups of lamps can in principle be carried out as follows:

1. a) Within a group of lamps by absorption between adjacent LEDs of this group of lamps or
2. b) cross-illuminant groups, the light emission of an LED of a first illuminant group being able to be detected by means of an LED of an adjacent illuminant group.

For example, method b) can be used within an LED chain along an LED strip. Since the distances are then larger, the signals received are often smaller. Here, a diagnosis of all LEDs of all lamp groups is possible within the scope of a diagnostic cycle or by sensible coding of the control, if necessary also during operation.

It is preferred to measure the photocurrent of an LED at times when it is not being driven (energized), that is to say is in an off state and therefore does not itself emit any light. Instead of the off state, the LED can also be switched to the second state and emit no light or an insufficiently large amount of light for measurement in an adjacent LED. Furthermore, at this time at least one other LED must be in the on state, i.e. emit light (with a sufficiently large light output), which also corresponds to the second state of the illuminant. This light must fall on the LED in the off state in sufficient quantity and have a suitable level so that light shines into the LED in the off state in such a way that a measurable photo current or a measurable photo voltage is produced.

Only the LED in the off state is preferably evaluated, in particular if a plurality of LEDs shine into the LED in the off state.

The photocurrent of a plurality of LEDs is preferably measured in parallel or quasi-parallel at times in which they are not activated, that is to say are in an off state (second state) and therefore emit no or negligibly little light.

To carry out the method according to the invention, an LED (not the received one) must be in the on state (first state) at the time of measurement, that is to say emit light. A sufficient amount of this light must fall on the LEDs in the off state and its level must be suitable for irradiating the LEDs in the off state in such a way that a measurable photocurrent results in each case. The LED in the on state is then preferably evaluated, preferably at least two, particularly preferably at least three, LEDs being evaluated.

The method according to the invention thus serves to carry out a test for light emission for a first illuminant, preferably for a first LED, of a luminaire which is provided for lighting or display purposes. The lamp has at least two lamps, preferably LEDs. The lamps can emit a first and a second light output. The amount of the first light output is greater than the amount of the second light output. The second light output is preferably zero or almost zero, which means that the illuminant in question preferably does not light in the off state.

The first illuminant is preferably switched on and thus brought into the on state (first state). The second illuminant is brought into the off state (second state), that is to say switched off.

The first illuminant is preferably arranged in relation to the second illuminant such that the first illuminant illuminates the second illuminant with the emitted light. A preferred analog-digital converter is used to measure an electrical parameter of the second illuminant Determination of a measured value for this parameter. In the case of a second LED as the second illuminant, this electrical parameter is preferably a photo voltage of the second LED, which it generates as a result of the irradiation, or a photo current of the second LED, which generates as a result of the irradiation.

The value of the selected parameter depends on the lighting in the form of the light output radiated into the second illuminant. Irradiation brings the second illuminant into a state in which this dependency can be measured. The second LED is therefore particularly preferably switched off in order to achieve a good signal-to-noise ratio.

The measured value - typically recorded by the analog-digital converter - is compared with a threshold value. This is preferably done by a program of a control computer or a computer to which the control computer sends the measured value or a value derived therefrom. This evaluates, for example, the first and / or second illuminant or the lamp as "possibly faulty" if the comparison of the measured value with the threshold value shows that the first light output of the first illuminant is too low or that the value of the parameter of the second illuminant is insufficient is. In the case of two LEDs, the result of the comparison of the measured value with the threshold value means that the photo voltage or the photo current that the second LED generates is too low. The photo current that is too low or the photo voltage that is too low is based either on the first light output of the first illuminant being too low and thus on the radiation being too low or on the sensitivity of the second illuminant too low to the radiation from the first illuminant. In this case, a defect in the second LED can typically be assumed.

In order to be able to make a better distinction, the method according to the invention is preferably extended to three lamps. Since there are three lamps of different colors in most lamp groups this extension can typically be used for luminaires with adjustable color.

In a preferred embodiment, to test a first lamp, a first test is carried out using the previously described method with the first and second lamps and a second test with the first and a third lamp. The third illuminant is also switched off and measured in accordance with the second illuminant. This results in a first test result for the first test and a second test result for the second test. The two test results can each have the values "in order" or "intact" or "possible defect" or "defective" of one of the two lamps involved in the respective test. The first test result can therefore have the values “in order” or “possible defect” for the first illuminant and for the second illuminant. The second test result can therefore have the values “in order” or “possible defect” for the first illuminant and for the third illuminant.

If both tests give the result "OK", the first lamp is intact.

If the first test is "intact" and the second test is "defective", then there is probably a defect in the third illuminant.

If the first test is "defective" and the second test "intact", then there is probably a defect in the second illuminant.

If the first test is "defective" and the second test is "defective", then there is a defect in the first illuminant, that is to say in the case of LEDs of the first LED.

These tests preferably do not run sequentially, but in parallel or with a slight delay.

The method according to the invention can be used for all illuminants, preferably in succession. Three or more illuminants are preferably always measured with one another, with one illuminant preferably being switched to the first state and emitting light and the other illuminants being switched in the second state (or off state) and not emitting any light (or negligible light output).

The method according to the invention is particularly preferably used for testing so-called RGB light modules. Such RGB light modules are preferably combinations of three LEDs of different colors. A first LED preferably has a blue color, a second LED a green color and a third LED a red color.

It is known that in the case of biodynamic light it is common to use a fourth color, which the human eye does not recognize with the same intensity, which controls the release of melatonin in the human body and thus influences the sleep / wake rhythm. More than three colors or focus wavelengths are preferably conceivable.

Furthermore, the combination with infrared LEDs as a transmitter for communicative purposes, for example for data transmission, distance measurement or transmission of sensor values, is conceivable. Therefore, light modules with more than four LED focus wavelengths are preferred.

Figur 1

eine schematische Abbildung eines Leuchtmoduls mit drei LEDs; und

Figur 2

ein Prinzipbild der erfindungsgemäßen Vorrichtung zur optischen Funktionsüberwachung der Lichtemission eines Leuchtmittels.

An exemplary embodiment of the invention is described below with reference to the attached figures. The embodiments shown here represent only a preference. The features shown can, however, also be used individually or in another combination, even if they are not explicitly shown. Show it:

Figure 1

is a schematic illustration of a light module with three LEDs; and

Figure 2

a schematic diagram of the device according to the invention for optical function monitoring of the light emission of a lamp.

The Figure 1 shows schematically a lamp group 1 with three lamps 3, 4, 5, which is designed as a light module. The light module is an LED module 2 with a first LED 10 and a second LED 12 and a third LED 14. One or more of these LED modules 2 can be integrated in a device or light. The LEDs 10, 12, 14 can emit light of different colors and / or have a different focus wavelength.

Figure 2 shows an example and schematically a device 20 for performing the method according to the invention. For example, it can be a lamp 6. The device 20 comprises an LED module 2 with three LEDs 10, 12, 14, whereby of course several LED modules 2 could also be included. For each lamp, the device preferably comprises a current source and a switch which is arranged between the current source and the lamp and by means of which the lamp can be energized, that is to say can be switched to a first state or a second state. The lamps can therefore preferably be switched on and off at least. The switches are preferably actuated by means of a control device or control unit.

In the preferred embodiment shown here, the device 20 has three switchable and / or controllable current sources S1, S2, S3. A control unit 22 controls and switches the current sources S1, S2, S3. The switchable current sources are preferably used instead of simple current sources and separate switches.

A measuring unit 24 measures the photo current and / or the photo voltage of the LEDs 10, 12, 14. The measured values are evaluated by an evaluation unit 26, preferably with them in the evaluation unit 26 or in one threshold values stored in the optional memory can be compared. The threshold values can be specific and individual for each LED 10, 12, 14.

The control unit 22, the measuring unit 24 and / or the evaluation unit 26 can be integrated in a microcontroller (.mu.C, microcontroller) or a computer system 28; in the embodiment shown, the three units are included in the computer system 28.

The LEDs are supplied by an energy source, for example a current source. The first LED 10 of the LED module 2 off Figure 1 is supplied with a first current I1 by the first current source S1. The second LED 12 of the LED module 2 is supplied by the second current source S2 with a second current I2 and the third LED 14 by the third current source S3 with a third current I3.

If a current I1, I2, I3 flows into one of the LEDs 10, 12, 14, the corresponding LED 10, 12, 14 is switched to a first state in which it emits a first light output and emits light. The first state is the on state. If no current I1, I2, I3 flows into the LED 10, 12 14, the corresponding LED 10, 12 14 is in a second state. In this preferred embodiment, the LED 10, 12, 14 does not emit any light output. The second state is the off state, in which the LED 10, 12, 14 is therefore dark or switched off.

A preferred analog-digital converter 30 (AD converter) can be connected via a preferably analog multiplexer 32, which is controlled by a computer system 28, to the output nodes of the first current source S1, the second current source S2 and / or the third current source S3 , Typically, this configuration is also used to monitor the voltage drop across the first LED 10, the second LED 12 and / or the third LED 14 and to detect failures during operation. Alternatively, a number of analog-to-digital converters 30 can be used if the multiplexer 32 is to be omitted.

The current sources S1, S2, S3 are controlled by the computer system 28 via a control bus 34 or control signal lines.

The current sources S1, S2, S3 shown as examples are preferably implemented in practical implementations as so-called high-side current sources, which draw their energy from the positive supply voltage. Of course, low-side power sources or others can also be used. Such high-side current sources are preferably implemented with the aid of a current mirror, a MOS diode for generating reference voltage and a current source transistor preferably being connected directly to this positive supply voltage. This preferred realization is in the Figure 2 however not shown. Instead, ideal power source symbols are shown that are related to the reference potential 36 (GND) and are therefore more theoretical in nature. The analog-digital converter 30 reports the measured values to the computer system 28. The computer system 28 carries out the proposed method.

The first LED 10 is particularly preferably measured by the computer system 28 having the first LED 10 supplied with a non-zero electrical first current I1 by switching on the first current source S1 and switching off the second current source S2 and the third current source S3. The computer system 28 preferably uses the multiplexer 32 and the analog-digital converter 30 to determine the second photo voltage of the second LED 12 and the third photo voltage of the third LED 14. The photo voltage of an LED 10, 12, 14 is the potential difference between the output node of the respective current source S1 , S2, S3 and the reference potential 36.

The second LED 12 is particularly preferably measured by the computer system 28 having the second LED 12 supplied with a non-zero electrical second current I2 by switching on the second current source S2 and switching off the first current source S1 and the third current source S3. Determined by means of the multiplexer 2 and the analog-digital converter 30 the computer system 28 then preferably the first photo voltage of the first LED 10 and the third photo voltage of the third LED 14.

The third LED 14 is particularly preferably measured by the computer system 28 having the third LED 14 supplied with a non-zero electrical third current I3 by switching on the third current source S3 and switching off the second current source S2 and the first current source S1. The computer system 28 preferably uses the multiplexer 2 and the analog-digital converter 30 to determine the second photo voltage of the second LED 12 and the first photo voltage of the first LED 10.

The first, second and third photo voltages determined in this way are preferably compared by the computer system 28 after each of these three measurement processes, each with two measurements, each with an associated (preferably specific) threshold value. The associated threshold values are preferably stored in the program or data memory of the computer system 28.

As can easily be seen, the redundancy of the measurements can preferably be used to carry out fewer measurements and to save time. If the computer system detects an error, it signals an error, for example, via a signaling line 38 or a data bus to a higher-level unit (not shown), for example a bus master or a control unit.

If a plurality of light modules or LED modules 2 are present in a device 20, the LEDs 10, 12, 14 can also be measured across modules. The LED modules 2 correspond to a lamp group 1, which preferably comprises three LEDs, particularly preferably a blue, a red and a green LED.

The measurement is preferably carried out by switching on the first LED 10 of the first LED module and emitting light or a light output which is in the switched-off LEDs of a second, preferably adjacent, LED module or illuminant group 1 causes a measurable photo voltage or photo current. The other LEDs of the first LED module are preferably switched off. The LEDs 10, 12, 14 of the second LED module are preferably switched off and are measured; the photo voltage is thus determined and compared with a stored threshold value. In this case, the device preferably has a plurality of current sources and preferably a plurality of multiplexers and / or analog-digital converters.

Such a diagnostic method enables the testing of illuminants, in particular LEDs, if they are measurably influenced by irradiation with light in at least one operating state. The advantages are not limited to this.

In contrast to the currently used diagnoses, which only provide indirect information about the LED current and voltage and thus do not allow a clear conclusion about an actual emission of light, the present invention enables a definite conclusion about an actual emission of light by a lamp or an LED.

Claims (15)

1. Method for carrying out a functional test of an illuminant of a luminaire for illumination or display purposes with at least three illuminants, wherein
   the illuminants (3, 4, 5) are connected such that they emit a specific first light output in a first state and a specific second light output in a second state, wherein the illuminants (3, 4, 5) are switched to the first state by being supplied with current und wherein the first light output is greater than the second light output,
   characterized by the following steps:

   - supplying the first illuminant (3) with current and switching it to the first state;

   - switching the second illuminant (4) to the second state;

   - switching the third illuminant (5) to the second state;

   - measuring a first measuring value of an electric parameter evoked in the second illuminant (4) by the first light output of the first illuminant (3);

   - measuring a second measuring value of an electric parameter evoked in the third illuminant (5) by the first light output of the first illuminant (3);

   - evaluating the measured first measuring value;

   - evaluating the measured second measuring value;

   - detecting a functional state of one of the illuminants, wherein the functional state allows a statement about the light emission capability of the illuminant;

   - recognizing that the first illuminant (3) is defective if the measured first and second measuring values are each below a threshold value, preferably a threshold value specific for the respective illuminant.
2. Method according to claim 1, characterized by the further step:

   - relating the second measuring value of the third illuminant (5) to the first measuring value of the second illuminant (4).
3. Method according to claim 1, characterized in that one of the illuminants (4, 5) switched to the second state is recognized as defective if the measured measuring value is below a threshold value specific for the illuminant (4, 5) and the measured measuring value for the other illuminant (4, 5), which is switched to the second state, is above a threshold value specific for this illuminant.
4. Method according to any one of the preceding claims, characterized in that the first illuminant (3) is recognized as intact if all measured measuring values of the illuminants (4, 5) switched to the second state are above the threshold values specific for the respective illuminants (4, 5).
5. Method according to claim 1, characterized in that an illuminant (4, 5) that is switched to the second state is recognized as intact if the difference between measured measuring value and associated specific threshold value has the same sign as the difference between the measured measuring value and the respective specific threshold value of the other illuminant (5, 4), which is switched to the second state.
6. Method according to any one of the preceding claims, characterized in that the second light output of the illuminants is so small that no light emission of the illuminant or a significantly smaller light emission compared to the first light output takes place, wherein preferably the second light output of each illuminant is smaller than the first light output of any illuminant.
7. Method according to any one of the preceding claims, characterized in that the illuminants (3, 4, 5) are LEDs (10, 12, 14).
8. Method according to the preceding claim, characterized in that all the LEDs (10, 12, 14) emit different colors and/or have different centroid wavelengths.
9. Method according to any one of the preceding claims, characterized in that the electric parameter is a photovoltage or a photocurrent.
10. Method according to any one of the preceding claims, characterized in that the luminaire (6) has two groups of illuminants (1), each group of illuminants (1) comprising at least one illuminant (3, 4, 5) and wherein an illuminant (3) of the first group of illuminants is switched to the first state and an illuminant (4, 5) of the second group of illuminants is switched to the second state.
11. Method according to the preceding claim, characterized in that at least two groups of illuminants (1) comprise three illuminants (3, 4, 5), wherein an illuminant (3) of the first group of illuminants is switched to the first state and an illuminant (4, 5) of the second group of illuminants is switched to the second state, preferably two illuminants of the second group of illuminants are switched to the second state, particularly preferably all illuminants of the second group of illuminants.
12. Device for carrying out a functional test of an illuminant of a luminaire for illumination or display purposes, comprising at least two illuminants (3, 4), a control unit (22), a measuring unit (24), an evaluation unit (26) and two switches, which are arranged between an illuminant (3, 4) and a power source and are switched by the control unit (22) and which are configured to switch an illuminant (3, 4) to a first state or a second state, wherein the illuminant (3, 4) emits a specific first light output in the first state and emits a specific second light output in the second state, which second light output is smaller than the first light output,
    wherein each illuminant (3, 4) can be supplied with current to be switched to the first state;
    characterized in that

    - the control unit (22) is configured and designed to supply the first illuminant (3) with current and to switch it to the first state and to switch the second illuminant (4) to the second state,

    - the measuring unit (24) is configured to detect a measuring value of an electric parameter at the second illuminant (4), which parameter is evoked by the first light output of the first illuminant (3), and

    - the evaluation unit (26) is configured to evaluate the measured measuring value and to detect a functional state of one of the illuminants (3, 4,5).
13. Device according to claim 12, characterized in that the device comprises a third illuminant (5), which can be switched to a first state and to a second state,
    wherein the illuminant (5) is configured to emit a specific first light output in the first state and to emit a specific second light output in the second state, which is smaller than the first light output,
    and
    wherein

    - the third illuminant (5) is supplied with current to be switched to the first state;

    - the control unit (22) is configured and designed to switch the third illuminant (5) to the second state,

    - the measuring unit (24) at the third illuminant (5) is configured to detect a second measuring value of an electric parameter, which is evoked by the first light output of the first illuminant (3),

    - the evaluation unit (26) is configured to evaluate the measured second measuring value and to detect a functional state of one of the illuminants (3, 4, 5), and

    - the evaluation unit (26) is configured to recognize a defect of the first illuminant (3) if the measured measuring value of the second illuminant (4) and the measured second measuring value of the third illuminant (5) are below a given threshold value.
14. Device according to claim 12 or 13, characterized in that the control unit (22), the measuring unit (24) and/or the evaluation unit (26) are integrated in a microcontroller or a computer system (28).
15. Device according to one of the claims 12 to 14, characterized in that the illuminants (3, 4, 5) are LEDs (10, 12, 14) and preferably the device (20) comprises an analog-to-digital converter (30) and particularly preferably a multiplexer (32).

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