WO2019234331A1

WO2019234331A1 - Method for continuously monitoring a desired luminous environment, and corresponding device

Info

Publication number: WO2019234331A1
Application number: PCT/FR2019/051288
Authority: WO
Inventors: Eric PIGEON; Olivier GEHAN; Tomas MENARD; Mathieu POULIQUEN; Philippe Maugars; Jean-Marc Paris; Abdelhak GOUDJIL
Original assignee: Ecole Nationale Superieure D'ingenieurs De Caen; Universite De Caen Normandie; Pm Company
Priority date: 2018-06-05
Filing date: 2019-05-31
Publication date: 2019-12-12
Also published as: FR3082093A1

Abstract

Disclosed is a method for continuously monitoring a desired luminous environment in a room illuminated at least partially by LEDs (5), comprising the following steps: a) defining an illumination by means of setpoint colorimetric coordinates (x, y, z); b) measuring the illumination of the room through a multispectral sensor; c) converting the measurement results of the illumination of the room into measurement colorimetric coordinates (x', y', z '); d) comparing the measurement colorimetric coordinates (x', y', z ') and setpoint coordinates (x, y, z); and identifying deviations (∆ x, ∆ y, ∆ z); e) applying the identified deviations to a corrector for generating control colorimetric coordinates; f) converting the control colorimetric coordinates into signals for controlling the LEDs; g) controlling the LEDs for illuminating the room; and h) returning to step b).

Description

Continuous control method of a desired light source, and corresponding device

DOM AL N E D E I NVENTI ON

The invention relates to a method for continuously monitoring the desired lighting environment in a room, and the corresponding device. More specifically, the invention relates to a method of continuously monitoring a desired lighting environment in a room at least partially illuminated by light emitting diodes (LEDs or LEDs). More particularly, the method according to the invention makes it possible to maintain a desired lighting atmosphere in a room by taking external lighting sources into account and / or by rejecting disturbances that may affect the desired lighting environment in the room. By disturbances, one understands the spectral and intensity drifts specific to the LEDs and the light disturbances independent of the LEDs. The drifts specific to the LEDs are related to their aging, to the variation of the temperature of their junctions and to the intensity of the current applied to drive them. LED-independent light disturbances are, for example, in a room with windows, variations in external illumination, or changes in room access conditions, such as door opening or closing, or a change in lighting conditions. the illumination inside the room as a fixture addition.

ANTERIOR ART R

EP 2 798 914 discloses an LED illumination system comprising three monochromatic series of LEDs and a fourth series of white LEDs. This illumination system considers the control of the light emitted by the LEDs only, to the exclusion of any other source of illumination. It has a control loop for each series of LEDs. This system uses a RGB sensor to measure the light emitted by the LEDs.

EP 2 236 007 discloses a method for controlling the color emitted by at least one modulated light source constituted by LEDs. The modulation makes it possible to distinguish the light emitted by each source and its identification by several detectors. In case of spectral drift, the detector corresponding detects a variation of intensity and controls a variation of opposite intensity, without action on the spectral drift. Light sources other than LEDs are not taken into account by the detectors.

The document EP 1 943 880 describes an illumination system with several LEDs corresponding to several colors, with a sensor for each color. It provides temperature compensation only of the individual LED drift.

The known systems for controlling the luminous environment of a room illuminated by LEDs are based on the measurement of the junction temperature of the LEDs or on the measurement of a detected intensity variation. In these systems, any variation in intensity detected is interpreted as a variation in light intensity and not as a spectral drift. Some systems also take into account the variations in the illumination outside the LEDs, but only consider the brightness independently of the notion of color. They thus achieve a partial and insufficient correction, which does not guarantee the maintenance of the desired spectrum by the user.

GOALS AND SUMMARY

One of the aims of the invention is to provide a method of continuously monitoring a desired lighting environment in a room at least partially lit by LEDs, which does not have the disadvantages and shortcomings of known systems.

Another object of the invention is to provide a continuous control device for a desired lighting environment in a room at least partially illuminated by LEDs, compensating for disturbances both specific to the LEDs and external to the LEDs.

Another object of the invention is the precise detection of the spectral drift of LEDs due to variations in the temperature of LED junctions, aging and other effects.

The subject of the invention is a method for continuously monitoring a desired lighting environment in a room at least partially lit by LEDs, characterized in that it comprises the following steps:

a) Definition of an illumination by means of colorimetric reference coordinates (x, y, z); b) Measurement of the illumination of the room through a multispectral sensor;

c) converting the measurement results of the illumination of the workpiece into measurement colorimetric coordinates (c ', y', z ');

d) Comparison of the measurement (c ', y', z ') and reference (x, y, z) colorimetric coordinates; and identification of deviations (Dc, Dg, Dz); e) Application of the identified discrepancies to a corrector to generate colorimetric control coordinates;

f) Conversion of control colorimetric coordinates into signals for LED control;

g) LEDs control for room illumination;

h) Return to step b).

According to one embodiment of the invention, the control of the LEDs is ensured by current by adjusting the amplitude of the current, and / or by modulating the pulse width of the current.

According to one embodiment, the illumination of the part is provided by at least one series of colored LEDs. This is, for example, monochromatic LEDs.

According to one embodiment, the number of sets of color LEDs is between one and six. Preferably, the number of sets of color LEDs is greater than or equal to two. More preferably, the number of sets of colored LEDs is between three and six.

According to one embodiment, the illumination of the room is measured by means of a multispectral sensor whose number of spectral channels is greater than that of the series of colored LEDs.

The multispectral sensor comprises, for example, interferential bandpass optical filters or color filters.

According to one embodiment, the number of spectral paths of the multispectral sensor is two more than that of color LED series.

The invention also relates to a continuous control device for a desired lighting environment in a room at least partially lit by LEDs, characterized in that it comprises: a-A colorimetric coordinate setting device (x, y, z) set for the illumination of the room;

b- A control device for each series of colored LEDs; c- At least one set of colored LEDs to illuminate the room;

d- A multispectral sensor of the illumination of the part making measurements of illumination with several spectral channels;

e- A converter of the measurements of room illumination made by the multispectral sensor, in measurement colorimetric coordinates (c ', y', z ');

f- A comparator of the reference colorimetric coordinates (x, y, z) and measurement coordinates (c ', y', z ') for the identification of deviations (Dc, Ay, Dz);

g- A corrector to generate control colorimetric coordinates from the identified deviations (Dc, Ay, Az);

h- A converter of the colorimetric coordinates of control in signals for the control of the LEDs.

D ESCRITI ON F ES FL GU RES

The invention is hereinafter described with reference to the accompanying drawings in which FIG. 1 is a block diagram of the continuous control device of a desired lighting environment in a room at least partially lit by LEDs;

Fig. 2 is a representation of the chromaticity pattern and the achievable color gamut of an exemplary embodiment of the invention with m = six sets of color LEDs.

Fig. 3 is a representation of a transmission spectrum of an exemplary embodiment of an eight-channel multispectral sensor according to the invention.

DETAILED DESCRIPTION

The invention aims to maintain a desired lighting atmosphere in a room illuminated at least partially by a LED luminaire. The light emitted by the luminaire is produced by a set of colored LEDs consisting of emitting color LEDs. The number of LEDs and their spectrum determine the color gamut achievable by the luminaire. By color gamut, we mean all the colors that the luminaire is capable of reproduce. This corresponds to the area of a convex polygon defined by the lines joining the different points defined by the coordinates of the color LEDs in the chromaticity diagram.

The device for continuously controlling a desired lighting environment in a room at least partially illuminated by LEDs according to the invention is represented symbolically in FIG. 1.

The colorimetric coordinates used (x, y, z) are, for example, tristimulus coordinates X, Y, Z, or other commonly used systems such as for example x, y, L; u, v, L or CCT ("Correlated Color Temperature").

According to one embodiment of the invention, the colorimetric coordinates x, y, L have been used. The control of the color coordinates (x, y) makes it possible to directly adjust the color in the room and the slaving of L makes it possible to regulate the luminous intensity in the room.

The device 1 for defining the light ambience receives as input the colorimetric coordinates (x, y, z) desired in the room. In order to avoid that the colorimetric coordinates requested are outside the gamut, an algorithm tests whether the desired colorimetric coordinates are in the gamut reachable by the emitting color LEDs. If the desired colorimetric coordinates are in the gamut, the output of the definition device 1 is (x, y, z). If the desired colorimetric coordinates are outside the gamut, the algorithm projects the setpoint to the limit of the gamut, which makes it possible to find the coordinates (x, y, z) as close as possible to the desired colorimetric coordinates. The definition device 1 transmits these colorimetric coordinates to the comparison device 2.

The definition device 1 thus makes it possible to define the colorimetric reference coordinates (x, y, z) for illuminating the part.

The comparison device 2 is a regulator comprising a comparator, a corrector and an anti-windup system (also called anti-saturation or anti-runaway). It takes as input the colorimetric coordinates of the setting device 1 and the colorimetric measurement coordinates of the converter 8. The converter 8 converts the data measured by the multispectral sensor 6 into colorimetric measurement coordinates (c ', y', z ').

The comparison device 2 outputs the colorimetric control coordinates to be transmitted to the conversion device 3. In this comparison device 2, the regulation consists of three elements: a- A comparator: it calculates the difference between the colorimetric coordinates setpoint of the definition device 1 and the colorimetric measurement coordinates of the converter 8.

b- A corrector: the target colorimetric coordinates and the difference between the colorimetric reference coordinates and the measurement colorimetric coordinates are then used to calculate control colorimetric coordinates (xc, yc, zc).

c- An anti-windup system: in order to avoid that the colorimetric coordinates of control (xc, yc, zc) are outside the gamut defined by the emitting color LEDs (which means a command not physically feasible and what could generating system instability), an anti-windup system is applied to the corrector actions in order to maintain the colorimetric control coordinates within the gamut achievable by the emitting color LEDs (in order to ensure physically achievable control).

The colorimetric control coordinates coming from the comparison device 2 are applied to the conversion device 3 which is a converter (a matrix inversion algorithm with constraints is used) which will transform the control colorimetric coordinates into m PWM cyclic ratios applicable to the m LED drivers that drive the m series of color LEDs in PWM or amplitude. The use of this algorithm makes it possible, for example, to impose constraints on the energy consumption of the luminaire or to minimize or maximize certain radiation for human beings, such as blue light. This new approach can save up to 30% energy for a bright atmosphere and this by promoting the use of LEDs with the best energy efficiency. The LED control signals are applied to the control devices 4 LEDs 5. It is provided m control devices 4, each providing control of a series of LEDs 5 color. The LEDs 5 provide illumination of the room, alone or in the presence of other light sources (artificial or natural). Each series of LEDs 5 is characterized by a well defined hue.

The illumination of the part is measured by means of the multispectral sensor 6, through band-pass color optical filters 7. The multispectral sensor 6 is composed of n> m (m being the number of series of emitting color LEDs) optical bandpass filters having transmission spectra distributed over the visible spectrum. Indeed, without this minimal excess (n> m), it is impossible to identify operating variations of LEDs such as spectral drifts related to temperature variations or aging LEDs. In an exemplary embodiment, the multispectral sensor 6 comprises eight band-pass optical filters of different colors (for m = six sets of color LEDs), covering the entire visible spectrum, and centered approximately on the following wavelengths. : 415, 445, 470, 510, 550, 585, 620 and 670 nm.

The main wavelengths of the eight bandpass optical filters 7 are independent of the wavelengths of the color LEDs. This allows a fine representation of the spectrum of light in the room.

The illumination measured by the multispectral sensor 6 via the interference optical filters 7 takes into account the light created by the LEDs, other light sources in the room, and wavelength variations of the LEDs due to aging or the variation of the junction temperature of the LEDs or the intensity of the current in the LEDs.

With this multispectral sensor, it is possible to differentiate a spectral drift emitting LEDs from a drop in intensity, unlike a simple color sensor (type RGB sensor). This type of sensor then makes it possible to control the colorimetric coordinates in a room by compensating for the variations of light due to the spectral drift of the LEDs and the presence of exogenous disturbances (for example, in a room with windows, variations exterior illumination or changes in room access conditions, such as opening or closing door, or a change of illumination inside the room as a fixture addition.)

The converter 8 makes it possible to transform the n spectral data measured by the multispectral sensor 6 into colorimetric measurement data (c ', y', z '). For this, a transfer matrix connecting the characteristics of the multispectral sensor 6 and the color space considered must be calculated. The transfer matrix is calculated using the transmission spectra of the n bandpass filters of the multispectral sensor 6 and the three stimuli of the standard system of the CIE (International Commission on Illumination). It is also possible to use an interpolator (neural network, fuzzy inference system, for example) to calculate this transfer matrix. The transfer matrix makes it possible to pass to the measurement coordinates (c ', y', z ') from the n spectral data.

In FIG. 1, the reference 9 designates all the disturbances independent of the LEDs (external or internal sources of illumination, natural or artificial). These disturbances may also be due to reflections on elements present in the room to be illuminated (mirrors, colored wallpapers, furniture, for example).

The use of a multispectral sensor 6 for measuring the light spectrum makes it possible to control the colorimetric coordinates and the overall light intensity in a room. A multispectral sensor comprises n bandpass optical filters whose transmission spectra are distributed as uniformly as possible in the visible spectrum. The filters are distributed so that their spectra overlap in order to have a measurement of all the wavelengths of the visible spectrum. A sensor of this type has the advantage of providing information on the measured spectrum in addition to the colorimetric coordinates. It delivers a measurement that is similar to a very coarse spectrometer. If the number of channels of the multispectral sensor satisfies the condition: n> m, it is possible to differentiate a spectral drift from the emitting color LEDs, a decrease in intensity, unlike a simple color sensor (type RGB sensor). Indeed, the sensor is able to detect not only the drop on a path of the sensor, but also the rise on the other or the sensor tracks that are nearby. What allows to identify the spectral drift and its meaning and to differentiate the drift from a simple drop in intensity.

The control of the LEDs is ensured by current: in modulation of pulse width and / or in amplitude of the power supply current of the LEDs, which makes it possible to ensure the illumination of the piece in a large range of levels and with a high accuracy.

The use of several series of LEDs makes it possible to choose the wavelengths emitted to ensure illumination and thus to reduce the portion of harmful blue wavelengths for certain people, for example.

In the particular embodiment of FIG. 2, the choice of color LEDs makes it possible to obtain the gamut or the largest color space possible. The LEDs selected are the Royal Blue LED (B), the Cyan LED (C), the Green LED (D), the Amber PC LED (A), the Deep Red LED (R) and the Mint LED (M). The Mint LED (M) is not used to expand the gamut, but rather to improve color rendering. The other five LEDs define the vertices of a convex polygon in the chromaticity diagram. These vertices are the colorimetric coordinates (x, y) of the color LEDs.

With reference to FIG. 3, for the measurement of the illumination in the room, the sensor 6 is a multispectral sensor, with n bandpass optical filters 7 whose spectra are distributed as uniformly as possible in the visible spectrum (Fl to Fn), here Fl at F8, to have a measurement of all the wavelengths of the visible spectrum.

The continuous control device of a desired light atmosphere in a room at least partially lit by LEDs, allows to vary the color over time, so as to promote, for example, a stimulating atmosphere or a relaxing atmosphere.

Claims

REV EN D I CATI ON S

A method for continuously monitoring a desired lighting atmosphere in a room at least partially lit by LEDs (5), characterized in that it comprises the following steps:

a) Definition of an illumination by means of colorimetric reference coordinates (x, y, z);

b) Measurement of the illumination of the room through a multispectral sensor;

f) Conversion of control colorimetric coordinates into signals for LED control;

g) LEDs control for room illumination;

h) Return to step b).

2- Method according to claim 1 characterized in that the control of the LEDs is ensured current by adjusting the amplitude of the current, and / or by modulation of the pulse width of the current.

3- Method according to claim 1 characterized in that the illumination of the room is provided by at least one series of colored LEDs (5).

4- Method according to claim 3 characterized in that the number of sets of colored LEDs is between one and six.

5. Method according to one of claims 1 to 4 characterized in that the measurement of the illumination of the room is provided by means of a multispectral sensor (6), whose number of spectral channels is greater than the series of colored LEDs.

6. The method of claim 5 characterized in that the number of spectral channels is two more than the series of color LEDs. 7- Device for continuously monitoring a desired lighting environment in a room at least partially lit by LEDs, characterized in that it comprises:

a-A colorimetric coordinate setting device (x, y, z) set for the illumination of the room;