EP2361489B1 - Led array comprising a light sensor - Google Patents

Description

The present invention generally relates to the operation of organic or inorganic LEDs or OLEDs. More specifically, the invention relates to a driving of such LEDs or OLEDs with the aid of a light sensor.

In FIG. 7 an arrangement for such operation is shown schematically.

Light from one or more LEDs 2, for example RGB LEDs, is preferably supplied to a diffusing screen or to another light-mixing element. A light sensor 1 inside or outside the LED light detects the light of the at least one LED 2 before or after the light mixture. A feedback signal 22 from the light sensor 1 is fed back to a control unit 23 as an actual value signal of the light generation. This signal reproduces at least the amplitude and, if necessary, can also make frequency or spectrum-specific statements.

As a setpoint signal, the control unit, for example internally or externally a dimming value signal 24 may be specified.

The control unit 23 controls the operation of the at least one LED 2 starting from a converter as in FIG. 7 shown power supply, which is supplied with a DC or AC input voltage U _i . The control unit 23 can, for example, control the power of one or more individual LEDs by PWM modulation. This described principle can be adopted in the present invention.

Such a structure is basically already out of the documents EP1399694 ( WO02 / 099333 ) US5471052 . US5783909 which relate to a lighting device with light-emitting diodes and light sensor arrangements for optical feedback.

Referring to Figures 1 and 2 will now be explained the problem of the spatial arrangement of a light sensor.

In FIG. 1 an LED lamp 12 is shown which has one or more LEDs 2. The lamp 12 has a housing ('Luminaire'), on whose front side a light exit surface is provided, on which the light cone 7 of the LED 2 strikes. The light cone 7 can be limited by a reflector wall.
More precisely, the light exit surface has transparent regions 4 for the exit of the light from the LED 2 and at least one darkened region 5. As indicated by the reference numeral 6, for example by reflection on the reflector wall 7, light from the LED 2 can be reflected in such a way so as to strike the side of the darkened area 5 facing the LEDs. The back of the darkened area 5 is formed such that the reflected light (reference numeral 6 in FIG FIG. 1 ) is directed in a light sensor 1 associated reflector 25. Thus, a part of the light emitted thereby by the LED, namely the part 6 in FIG. 1 , desired the light sensor 1 supplied.
As inevitably already out FIG. 1 However, this arrangement has the disadvantage that the darkened area 5 in the light exit surface on the one hand aesthetically, on the other hand, but also adversely affects the lighting effect achieved. Finally, this region constitutes an interruption of the transparent and thus also light-emitting regions 4 of the light exit surface.
In FIG. 2 another problem of this arrangement of the light sensor 1 is illustrated. Ambient light denoted by the reference numeral 9 in FIG FIG. 2 can come from outside the LED lamp 12 coming through the transparent areas 4 on the back 26 of the darkened area, thus gets into the area of the light sensor reflector 25 and is perceived as a disturbance to the sensor 1.

It is an object of the invention to provide an LED array with light sensor for controlling and / or regulating the operation of at least one LED, which is less affected by incident on the LED array ambient light.
This object is achieved according to the invention by the features of the independent claims. The dependent claims further form the central idea of the invention particularly advantageous.

• wenigstens eine auf einem Träger angeordnete LED, vorzugsweise mehrere LEDs wenigstens zweier unterschiedlicher Farben,
• eine die wenigstens eine LED aufnehmendes Gehäuse mit einer Lichtaustrittsfläche, durch die ein Hauptlichtkegel der wenigstens einen LED tritt,
• wenigstens einen Lichtsensor, und
• eine mit der wenigstens einen LED und dem Lichtsensor funktionell verbundene Steuereinheit,

wobei auf den Lichtsensor Sekundärlicht trifft, das nicht direkt oder indirekt von dem Hauptlichtkegel aus erzeugt ist.A first aspect of the invention relates to an LED array comprising:

• at least one LED arranged on a support, preferably several LEDs of at least two different colors,
• a housing housing at least one LED with a light exit surface through which a main light cone of the at least one LED passes;
• at least one light sensor, and
• a control unit operatively connected to the at least one LED and the light sensor,

wherein the light sensor is incident on secondary light which is not generated directly or indirectly from the main light cone.

In this case, the secondary light can strike the light sensor from a further light exit surface of the at least one LED. The further light exit surface is spatially separated from a light exit surface of the at least one LED, at which the main light cone exits.

The further light exit surface can be arranged on the rear side facing away from the main light cone of the LED chip. The secondary light can pass through at least one recess in a carrier on which the LED is mounted to the back of the carrier. The light sensor is preferably arranged in a region on the rear side of the carrier.

Light from an LED, in particular an OLED (organic LED), can reach the back of the carrier through a plurality of recesses.

The secondary light may emanate from another LED which is aligned with that at least one LED from which the main light cone exits.

The further LED can be arranged on the same side or on the backside of a carrier on which at least one main light cone LED is arranged.

The LED array may include a plurality of LEDs of different colors, preferably at least one in the green, red, and blue spectrum, respectively.
The LED assembly may include a lens.
The LED array may comprise at least one color conversion material converted white LED.
The light sensor may have one or more photodiodes, which are preferably color-specific.
A lighting system can have an LED arrangement according to the invention.
Further advantages, characteristics and features of the invention will now be explained with reference to the figures of the accompanying drawings.

Fig. 1

zeigt eine aus dem Stand der Technik bekannte Anordnung eines Lichtsensors in einer LED-Leuchte,

Fig. 2

illustriert den negativen Einfluss von Umgebungslicht bei einer Lichtsensoranordnung gemäß dem Stand der Technik,

Fig. 3

zeigt ein Beispiel mit abgeglichenen LEDs,

Fig. 4

zeigt ein Beispiel mit abgeglichenen LEDs, die räumlich getrennt zu den Hauptbeleuchtungs-LEDs angeordnet sind,

Fig. 5

zeigt ein erstes
Ausführungsbeispiel der Erfindung, bei der der Lichtsensor im Vergleich zu einer Trägerebene wenigstens einer LED zurückversetzt ist,

Fig. 6

zeigt eine Abwandlung des Ausführungsbeispiels von Figur 5 dahingehend, dass eine einzige LED bzw. OLED mehrere Ausnehmungen in einen zurückversetzten Raum mit dem Lichtsensor 1 mit Licht versorgt, und

Fig. 7

zeigt schematisch die grundsätzliche Wirkungsweise eines rückgekoppelten Lichtsensors bei der LED-Ansteuerung, wie sich auch bei der vorliegenden Erfindung verwendet werden kann.

Showing:

Fig. 1

shows a known from the prior art arrangement of a light sensor in an LED light,

Fig. 2

illustrates the negative influence of ambient light in a light sensor arrangement according to the prior art,

Fig. 3

shows an example with adjusted LEDs,

Fig. 4

shows an example with adjusted LEDs, which are arranged spatially separated from the main illumination LEDs,

Fig. 5

shows a first
Embodiment of the invention, in which the light sensor is set back compared to a carrier plane of at least one LED,

Fig. 6

shows a modification of the embodiment of FIG. 5 in that a single LED or OLED supplies a plurality of recesses in a recessed space with the light sensor 1 with light, and

Fig. 7

schematically shows the basic operation of a feedback light sensor in the LED drive, as can also be used in the present invention.

Referring to FIG. 3 Let us now explain an example.
Again, an LED lamp 12 is provided with a housing 3 and an LED 2 or an LED arrangement. It can be provided a reflector 7 to direct the beam of light from the LED 2 to a light exit surface 10 of the LED light. The light exit surface 10 is preferably transparent throughout. Thus, it has no darkened areas compared to the prior art, ie at least no darkened areas which are surrounded by transparent areas and thus represent "dark islands" of the light exit area.
The light from the LED 2 is not reflected toward the light sensor 1. This results in an aesthetically and illumination-technically preferred uniform light exit surface 10. This light exit surface 10 can be designed as a diffuser, for example, which represents only one example of a light mixing element. This will preferably be the case if several differently colored LEDs 2 are provided for example in the spectra red, green, blue. Alternatively or additionally, the LED arrangement 2 can also have one or more color-converted white LEDs. The LED or LED arrangement 2 is arranged on a support 8, which can also achieve, for example, several functions such as the electrical supply (board) or a cooling effect or heat dissipation. This example of FIG. 3 are for light feedback to the control unit (see FIG. 7 ) and the secondary LEDs 11 are provided. These secondary LEDs 11 are matched to the main illumination LEDs 2 in such a way that they have the same spectrum and preferably also the same temperature properties.
As in FIG. 3 illustrated, the secondary elements 11 are preferably arranged in the immediate vicinity of the LEDs 2 and therefore within the housing 3 of the LED lamp 12. Particularly preferred is the arrangement of the elements 11 on the same support 8 and preferably there on the back of the carrier. 8

Thus, the secondary LEDs 11 radiate in an area provided on the back side 27 of the carrier 8. In this area, as shown, the light sensor 1 is arranged.

The light sensor 1 is therefore sealed off by the non-transparent carrier 8 from the space defined between the carrier 8 or the LED 2 and the light exit surface 10.

Thus, ambient light, which as schematically shown, and provided with a reference numeral 6, can fall from the outside through the light exit surface 10 in the space between the support 8 and the light exit surface 10, do not fall on the light sensor 1 and thus can not represent an interference signal.
The secondary LEDs 11 are preferably from the control unit (23 in FIG. 7 ) are driven in the same manner as the main light LEDs 2. Thus, a secondary light is generated purely for measurement purposes, which is not affected by the ambient light.
Referring to FIG. 4 Let us now explain an example that in some way a modification of the embodiment of FIG. 3 shows. Again, secondary light LEDs 16 are provided, which are now, however, provided spatially separated from the LED lamp 12. In the example shown, these secondary light LEDs 16 and also the light sensor 1 of the control / converter unit 14, 15 are assigned. This unit is connected to the LED lamp 12, for example via a supply cable 13 for driving the LEDs 12. In this example, therefore, the measurement of Light characteristics on the one hand indirectly via the secondary light LEDs 16 and on the other hand in a spatially separated location with respect to the LED lamp 12 and the main light LEDs provided there 2. In this case, as shown schematically in FIG. 4 illustrated, preferably a temperature sensor 28 is provided on an LED lamp 12, the output signal of the control / drive unit 14, 15 is supplied, since the temperature of the secondary light LED 16 may differ significantly due to the spatial separation of the main light LEDs 2 ,

FIG. 5 now shows an embodiment in which the incident light to the light sensor 1 is not generated by secondary light LEDs 11, 16, but by the main light LEDs 2.

According to this exemplary embodiment, the one or more LEDs 2 have, in addition to the LED exit surface 29 facing the light exit surface 10, a further exit surface 30. In the example shown, the exit surface 30 of the at least one LED 2 is arranged on the rear side. In the carrier, which may be formed as an auxiliary carrier 17, one or more recesses 19 (for example bores) are provided, through which the light passes from the further exit surfaces 30 of the LED 2 into the region behind the auxiliary carrier 17. The back of the LED 2 overlaps one or more recesses 19th

In the example shown, a space is provided between the auxiliary carrier 17 and a main carrier 18, in which the light thus passes from the further exit surfaces 30 through the recesses 19. In this room, the light sensor 1 is arranged.

FIG. 6 shows a modification of the embodiment of FIG. 5 to the effect that a flat LED 21, preferably an OLED covers a plurality of recesses 19. Thus, the light passes from the exit surface 30 on the rear side of the planar LED 21 through a plurality of recesses 19 in the space in which the light sensor 1 is arranged, which leads to a certain averaging of the measurement of the light characteristic of the LED 21.

As usual in the prior art, the light sensor may be provided to detect characteristics of the LED 2, since these may depend on the temperature, the aging, etc. of the LED. In this case, the light sensor can in particular be color or spectrum-selective, so that a feedback signal for color value stabilization (color coordinate in the CIE system) can be used by selective control of LEDs of different colors.

The invention proposes a sensor arrangement in which it is ensured that the light sensor is actually not detected by the LED and not by a combination of, for example, the light from the LED with ambient light.

In this case, the embodiment of FIG. 5 and 6 be modified to the effect that the light sensor 1 is not arranged in a space behind the support 17, but rather in the support 17 is provided a recess that he can thus also detect light from the LED 2, without the recesses 30 are necessary ,

It should be noted that the term 'light sensor' in the present description and Also in the claims always one or more light sensors are to be understood, each of which may have, for example, one or more photodiodes.

LIST OF REFERENCE NUMBERS

1

light sensor

2

LEDs

3

luminaire housing

4

Transparent pane, for example a diffuser

5

Darkened area of the light exit surface

6

Reflected light

7

Main beam

8th

LED support

9

ambient light

10

Continuous diffuser

11

Matched LEDs

12

LED light

13

power cable

14

Separate sensor and possibly driver / converter unit

15

Driver / converter circuit

16

Matched LEDs

17

motherboard

18

subcarrier

19

recesses

20

secondary light

21

OLED

22

Feedback signal from the light sensor

23

control unit

24

Setpoint specification DIMM

25

Light sensor reflector

26

Back of the darkened area 5

27

Rear of the carrier 8

28

temperature sensor

29

First light exit surface

30

Further light exit surface

Claims (9)

1. An LED arrangement having:

   - at least one LED (2) arranged on a non-transparent support, in particular, a circuit board, preferably a plurality of LEDs of at least two different colors,

   - a housing for accommodating the at least one LED (2), having a light exit surface (10), and

   - at least one light sensor (1), and

   - a control unit that is functionally connected to the at least one LED (2) and the light sensor (1) for controlling the at least one LED (2), wherein the light sensor (1) is arranged outside of the area defined by the light exit surface (10) and the support and wherein the support is designed to prevent the sensing of the light from the light exit surface (10) and the ambient light by the light sensor (1),

   wherein the at least one LED (2) is arranged on the support and the light sensor (1) is set back behind the plane formed by the support,
   and
   wherein the at least one LED (2) has a further exit surface (30) in addition to the LED exit surface (29) facing the light exit surface (10),
   characterized in that
   wherein in the support one or a plurality of recesses (19) are provided, through which the light from the further exit surface (30) of the at least one LED (2) passes into the area behind the support, in which the sensor (1) is arranged, and the back side of the at least one LED (2) overlaps one or a plurality of recesses (19).
2. An LED arrangement according to Claim 1,
   wherein the further exit surface (30) is spatially separated from a light exit surface of the at least one LED (2), at which the main light cone exits.
3. An LED arrangement according to Claim 1 or 2,
   in which light from an LED (2), in particular an OLED, passes through a plurality of recesses (19) on the back side of the support.
4. An LED arrangement according to any one of the preceding claims, wherein the shading means are provided, which prevent incident ambient light from falling on the light sensor (1) from the outside of the housing (3) through the light exit surface (10) or ambient light from falling from the outside of the area accommodating the sensor (1).
5. An LED arrangement according to any one of the preceding claims,
   having a plurality of LEDs (2) of different colors, preferably at least one in the green, red or blue spectrum.
6. An LED arrangement according to any one of the preceding claims,
   having a diffusion disc.
7. An LED arrangement according to any one of the preceding claims,
   having at least one color conversion material-converted white LED.
8. An LED arrangement according to any one of the preceding claims,
   wherein the light sensor (1) has one or a plurality of photodiodes, which are designed preferably to be color-specific.
9. A lighting system having an LED arrangement according to any one of the preceding claims.

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