EP4147537A1

EP4147537A1 - Method for controlling a lighting system of a motor vehicle

Info

Publication number: EP4147537A1
Application number: EP21722269.4A
Authority: EP
Inventors: Onoriu Puscasu
Original assignee: Valeo Vision SAS
Current assignee: Valeo Vision SAS
Priority date: 2020-05-05
Filing date: 2021-05-05
Publication date: 2023-03-15
Also published as: US20230164894A1; WO2021224340A1; FR3109919A1; CN115517018A; FR3109919B1

Abstract

The invention relates to a method for controlling a lighting system of a motor vehicle comprising a generator for generating a pulse-width modulated signal having a first peak intensity or a second peak intensity higher than the first peak intensity, and a light source; characterised in that it comprises the following steps: Reception of an instruction to emit a light beam according to a given target luminous flux; Selection of a peak intensity from the first and second peak intensities depending on the given target luminous flux; Determination of a target duty cycle of a pulse-width modulated signal having the selected peak intensity depending on the given target luminous flux and the efficiency of the light source; Generation of a target signal having the selected peak intensity and the determined target duty cycle and provision of the target signal to the light source.

Description

Title of the invention: Method of controlling a motor vehicle lighting system

The invention relates to the field of automotive lighting, and in particular the lighting of the interior of a motor vehicle.

[0002] A light system of a motor vehicle is controlled in the usual way so as to emit a light beam having characteristics in accordance with an instruction, which can for example be set by an occupant of the vehicle. This is for example the case for the lighting of the interior of a motor vehicle, according to which an occupant of the vehicle can request to be illuminated by a light of a given color and / or of a given luminous flux. It is therefore necessary to set up a control method for the lighting system illuminating the passenger compartment which is sufficiently precise and robust so that the characteristic or characteristics of the light beam emitted by this system correspond substantially to those required by the occupant.

[0003] In a known manner, the light sources of the light systems of motor vehicles are controlled by means of signals modulated in pulse width, which are particularly suitable when these light sources are light emitting diodes. It has in fact been established that the luminous flux emitted by a light emitting diode is a function of the power of the signal which feeds it. It is therefore known to determine a value of the duty cycle of a pulse width modulated signal as a function of the desired flux, and to supply the diode with a signal having this determined duty cycle. Usually, this signal is a periodic signal having, for each period, a pulse formed by a ramp up to a peak intensity, which is maintained for an activation time and a ramp down to a zero value. , which is maintained for a deactivation time until the next period. The luminous flux emitted by the diode is thus determined by the area of the pulsation, and therefore by the various parameters which are the rise time, the fall time, the activation time and the peak intensity.

To avoid a flickering effect which is perceptible, the frequency of the signal must be particularly high, for example greater than 300 Hz. Given the need for precision mentioned above, this frequency requires being able to generate pulses with a particularly short minimum activation time, for example less than 50 ns, in particular so as to be able to control the emission of a light beam whose light flux is low or to be able to obtain a resolution in light flux and / or in color that is important. However, generators of pulse width modulated signals conventionally used are not capable of generating pulses whose rise and / or fall times are less than 100 ns. Consequently, the minimum area of the pulsation generated by these known generators does not make it possible to meet the need for precision mentioned above.

[0005] The present invention falls within this context, and aims to overcome the aforementioned drawbacks by proposing a method for controlling a lighting system of a motor vehicle, which is sufficiently precise and robust so that the one or more characteristics of the light beam emitted by the light system correspond substantially to those required by the occupant, including when it is required a low luminous flux or a weak variation of the luminous flux and / or of the color of this light beam.

[0006] For these purposes, the subject of the invention is a method for controlling a lighting system of a motor vehicle comprising: a. a pulse width modulated signal generator, the generator being adapted to generate a pulse width modulated signal having a first peak intensity or a second peak intensity greater than the first peak intensity, and b. a light source arranged to emit a light beam according to a light flux determined as a function of said pulse width modulated signal.

[0007] According to the invention, the method comprises the following steps: a. Receipt of an instruction to emit a light beam from the light source according to a given target light flux; b. Selection of a peak intensity among the first and second peak intensities according to the given target luminous flux; vs. Determination of a duty cycle of a pulse width modulated signal having the selected peak intensity according to the given target luminous flux and the efficiency of the light source; and D. Generating a pulse width modulated setpoint signal having the selected peak intensity and the determined setpoint duty cycle and supplying said pulse width modulated setpoint signal to the light source.

[0008] Thus, for the same given target intensity, it is possible to generate either a first pulse-width modulated signal whose pulses towards the first peak intensity have a first activation time determined as a function of this target intensity, of the first peak intensity and, directly or indirectly, of the efficiency of the light source for this first peak intensity, i.e. a second pulse-width modulated signal whose pulses towards the second peak intensity have a second activation time , necessarily shorter than the first, determined as a function of this target intensity, of the second peak intensity, greater than the first peak intensity and, directly or indirectly, the efficiency of the light source for this second peak intensity. It has in fact been observed that the efficiency of a light source, namely the ratio between the luminous flux actually emitted by the source and the electrical power required for the target light intensity, decreases when the peak intensity of the current which is provided to him increases.

[0009] It is therefore understood that, according to the invention, the luminous flux of the beam emitted by the light source is identical, whether it is provided with the first signal or the second signal and regardless of its effectiveness. Therefore, it is possible to select either of the first and second peak intensities, depending on the required target luminous flux. Thus, when this required luminous flux is particularly low, or even when a small variation in the luminous flux is required, the first peak intensity will for example be selected, so that it is possible to generate a signal whose pulsations have a sufficiently long activation time for them to be carried out by the generator.

By pulse width modulated signal, also called PWM (English Puise Width Modulation) is meant a periodic signal characterized in that over a period, it comprises a pulse having a peak intensity for a given duration said activation time. The ratio between the activation time and the period is called the duty cycle of this signal.

Advantageously, the light source is supplied electrically by means of the pulse width modulated reference signal. Where appropriate, the luminous flux of the beam emitted by the light source is determined by means of the following equation. [Math.l]

Where Y is the value of the luminous flux of emitted by the light source, Y _max is the maximum luminous flux that the light source is capable of providing for the selected peak intensity, T _PWM the period of the reference signal, T _onC the activation time of a pulse of the setpoint signal. It should be noted that this maximum luminous flux is a function of the efficiency of the light source for the peak intensity selected.

In one embodiment of the invention, the light system comprises three light sources, each source being able to emit a light beam of a predetermined color. Where appropriate, the step of receiving a transmission instruction comprises receiving an instruction to transmit a light beam by the light system according to a given color and a given target global light flux. This step can optionally further comprise the determination of a given target light flux for each of the light sources from said colors and overall luminous flux given. For example, the light sources can be semiconductor light emitting chips each capable of emitting a light beam of red, green and blue color respectively. Where appropriate, the chips can be arranged in the vicinity of one another to form an RGB light unit, also called RGB (from the English Red, Green, Blue).

Advantageously, the method comprises a step of determining a setpoint duty cycle and a step of generating and supplying a setpoint signal for each of the light sources of the light system. In other words, for each light source of the light system, it is determined, as a function of the target light flux determined for this light source from the instruction received and, directly or indirectly, the efficiency of this light source , a setpoint duty cycle of a signal P WM having a selected peak intensity and a setpoint signal P WM is generated having this selected peak intensity and this determined setpoint duty cycle, which is specific to this light source and to which it is provides it.

Advantageously, for each light source, the set duty cycle ratio is determined so that the color and the luminous flux of the sum of the light beams emitted by the three light sources correspond substantially to the given color and to the given overall luminous flux .

[0016] For example, it is possible to consider that each of the light sources is capable of emitting a light beam of a different predetermined color depending on whether it is supplied with a signal P WM having the first or the second peak intensity. In other words, the coordinates, on a chromaticity diagram, of the predetermined color of the light beam that each light source can emit vary according to the selected peak intensity and according to the efficiency of this light source for this selected peak intensity. The step of determining the setpoint duty cycle, for each light source, can thus comprise determining an average luminous flux that this light source must emit, so that the barycenter of the coordinates of the predetermined colors, for the selected peak value, weighted by these mean luminous fluxes correspond to the given color of the instruction received and so that the luminous flux of the sum of the light beams thus emitted is substantially equal to the overall luminous flux. Each setpoint duty cycle for each of the light sources can then be determined by the ratio between the average luminous flux determined for this light source and the maximum luminous flux obtained for this light source with the selected peak intensity, this maximum luminous flux being dependent on the efficiency of this light source.

If desired, the step of selecting the peak intensity is common for all light sources of the light system. In other words, the method comprises a single step of selecting a peak intensity and the setpoint signals generated for each of the light sources have the same selected peak intensity.

[0018] For example, the step of selecting the peak intensity may comprise the comparison of the given overall luminous flux with a predetermined threshold value, the first peak intensity being selected if the overall luminous flux is less, and in particular less than or equal. , at said threshold value and the second peak intensity being selected if the overall luminous flux is greater than said threshold value. This characteristic makes it possible to obtain a peak intensity quickly and economically in terms of calculation time.

According to another example, the step of selecting the peak intensity can comprise the comparison of the smallest value of the target light fluxes determined for each of the light sources of the light system with a predetermined threshold value, the first peak intensity being selected if this smallest value is less than said threshold value and the second peak intensity being selected if this smallest value is greater than said threshold value. This characteristic makes it possible to achieve particularly high color resolution.

[0020] As a variant, the method may include a step of selecting the peak intensity for each of the light sources of the light system, for example as a function of the target light flux determined for this light source.

In one embodiment of the invention, the three light sources form a first light unit of the light system, and the light system comprises a second light unit comprising three light sources each capable of emitting a light beam of one color predetermined. In particular, each light source of the second unit may be able to emit a light beam of color substantially identical to that of the light beam that one of the light sources of the first light unit can emit. Where appropriate, the method may include a step of determining a setpoint duty cycle and a step of generating and supplying a setpoint signal for each of the light sources of each of the light units of the lighting system, the steps of providing a setpoint signal for the light sources of each light unit of the light system being time multiplexed. In other words, setpoint signals are supplied alternately and periodically to the light sources of the first light unit, and to the light sources of the second light unit, the setpoint signals being supplied simultaneously to the light sources of the same light unit. . This feature makes it possible to simplify the production of the lighting system and to save the ports of a controller controlling the power supply of the lighting units. If applicable, the stages of determination of the setpoint duty cycle for each light source are renewed at each period of the multiplexing.

Advantageously, the lighting system comprising a single controller comprising three signal generators modulated in pulse width, each generator being intended to generate a reference signal and to supply this reference signal to one of the light sources of each light unit.

[0023] For example, the controller has two inputs that can each be activated or deactivated selectively to allow the passage of an electric current and three outputs each intended to receive a reference signal generated by one of the generators. Each input of the controller is connected to one of the light units, so that it is commonly connected to the light sources, including the anodes of the light sources, of that light unit. Each output is connected in a common way to one of the light sources, in particular to the cathode of one of the light sources, of each light unit. In particular, each output is connected in a common way to the light sources of the light units which are able to emit a light beam of a substantially identical color. The controller periodically checks the activation and deactivation of each of the inputs so that one is activated while the other is deactivated. Thus, each of the light sources of each light unit receives a setpoint signal for a given time during which it emits a light beam and during which the light sources of the other light unit do not emit a light beam. If necessary, the frequency of switching on and off of the inputs is greater than 500 Hz, so that the alternation of emission and deactivation of light sources is not perceptible by a human eye.

The invention also relates to a light system of a motor vehicle, comprising at least one pulse width modulated signal generator and a light source arranged to emit beam light flux according to light flux determined as a function of said signal pulse width modulated; the light system being arranged to implement the method according to the invention.

Advantageously, the light system is a system for lighting the interior of the motor vehicle

The present invention is now described with the aid of illustrative examples only and in no way limiting the scope of the invention, and from the accompanying illustrations, in which:

[0027] [fig.l] shows, schematically and partially, a light system of a motor vehicle according to a first embodiment of the invention;

[0028] [fig.2] shows a method of controlling the light system of [fig.l] according to one embodiment of the invention; [0029] [fig.3] shows a chromaticity diagram used in the process of the

[fig-2]

[0030] [Fig.4] shows examples of pulse width modulated signals generated according to the method of [Fig.2]; and

[0031] [Fig.5] shows, schematically and partially, a lighting system of a motor vehicle according to a second embodiment of the invention.

[0032] In the description which follows, the elements which are identical, by structure or by function, appearing in different figures retain, unless otherwise specified, the same references.

[0033] There is shown in [fig.l] a lighting system S according to a first embodiment of the invention, the system S forming a lighting system for the interior of a motor vehicle.

For this purpose, the system S comprises a controller 1 provided with three generators 21, 22, 23 of pulse width modulated signals and three light sources 41, 42, 43. Each of the generators 21, 22 and 23 supplies power one of the light sources 41, 42 and 43.

Each of the light sources 41, 42 and 43 is a semiconductor chip capable of emitting a light beam of red, green and blue color respectively. These three light sources are arranged in the vicinity of one another to form a 4 RGB light emitting diode.

Although the example of [fig.l] only represents a single RGB light-emitting diode 4, it will be possible to provide, without departing from the scope of the invention, that the lighting system S comprises a plurality of RGB light-emitting diodes arranged in different places of the passenger compartment of the motor vehicle.

The controller 1 is arranged to receive, for example from a central computer of the motor vehicle, emission instructions I requiring the emission by the RGB light-emitting diode 4 of a light beam of a given color C and d 'a given global luminous flux Y _G. On receipt of an instruction I, the controller 1 is arranged to control the generators 21, 22 and 23 so that each generator generates, from a periodic signal supplied by an oscillator 3, a signal modulated in width of pulse supplying one of the light sources 41, 42 and 43. Each light source thus emits a light beam having a light flux such that the sum of the three light beams forms, by additive synthesis, a light beam having the given color C and the global luminous flux given Y _G.

In conjunction with [Fig.2], we will now present a method according to an embodiment of the invention, implemented by the light system S so that the color of the light beam emitted by the RGB diode 4 substantially matches the given color required in check instruction I. The controller 1 comprises a computer 10 arranged to receive G transmission instruction I and to select, during a first step El, a peak electrical intensity I _c from among two peak intensity values I _cl and I _c2 in function of the value of the global luminous flux Y _G required in the emission instruction I. The first value I _cl will be selected if Y _G is less than or equal to Y _s and the second value I _c2 will be selected if Y _G is greater than _Ys . It should be noted that the value I _c2 is greater than I _cl .

For example, I _cl could be 1mA and I _c2 could be 20mA.

The computer 10 thus transmits this selected value I _c to the generators 21, 22 and 23 so that the signals have the selected peak intensity.

In a second step E2, computers 11, 12 and 13 determine, each in a step E21, E22 and E23 specific to each light source 41, 42 and 43, an average luminous flux Y _m1 , Y _m2 , Y _m3 that this light source must emit so that the light beam emitted by the RGB diode 4 has the color C and the overall luminous flux Y _G required in the emission instruction I, as a function of the value of the peak electrical intensity I _c which has been selected.

There is shown in [Fig.3] a chromaticity diagram. On this diagram have been identified the colors RI, VI and B1 of the light beams which the light sources 41, 42 and 43 are capable of emitting when each supplied with a pulse width modulated signal having the peak value I _cl and a duty cycle of 100%. It should be noted that for this 100% duty cycle and this peak intensity I _cl , each light source emits a light beam of maximum luminous flux Y _max1c1 , Y _max2c1 and Y _max3c1 , depending on the efficiency of this light source at this peak intensity I _c1 . The colors R2, V2 and B2 of the luminous fluxes which the light sources 41, 42 and 43 are capable of emitting have also been identified when they are each supplied with a pulse width modulated signal having the peak value I _c2 and a duty cycle of 100%. Likewise, for this 100% duty cycle and this peak intensity I _c2 , each light source emits a light beam of maximum luminous flux Y _max1c2 , Y _max2c2 and Y _max3c2 , depending on the efficiency of this light source at this peak intensity I _1c. It can thus be seen that the color coordinates of the light beam that a light source can emit differ as a function of the peak intensity selected. Finally, we have shown an example of a given color C required in a received instruction I. The position of this color C can be considered on the one hand as a barycenter of the colors RI, VI and B1 assigned by weights which correspond respectively to the luminous fluxes. Y _m11 Y _m22 and Y _m31 sought for the first peak intensity I _c1 . On the other hand, the position of this color C can also be considered as a barycenter of the colors R2, V2 and B2 affected by weights which correspond respectively to the luminous flux Y _m21 , Y _m22 and Y _m32 sought for the second intensity. peak I _C2 . The determination of the average luminous flux Y _m1 , Y _m2 and Y _m3 can thus be carried out by the selection of a triplets of colors RI, VI, B 1 or of a triplets of colors R2, V2, B2 depending on of the peak intensity selected on and by searching for the weights which should affect these colors so that their barycenter corresponds to the required color C, and also so that the sum of the luminous fluxes corresponds substantially to the required overall luminous flux Y _g .

In a third step E3, the computers 11, 12 and 13 determine, each in a step E ₃₁ , E ₃₂ and E ₃₃ specific to each light source 41, 42 and 43, a setpoint duty cycle, or in l case an activation time T _on1, _on2 T _on3 and T, via the ratio between the luminous flux Y _m1, Y _m2 and _m3 Y determined for each light source and the maximum luminous flux of this source for the peak intensity selected. Each computer 11, 12 and 13 then supplies the activation time that it has determined to one of the generators 21, 22 and 23.

In a fourth step E4, each generator 21, 22 and 23 generates, in a step E41, E42 and E43 specific to each light source 41, 42 and 43, from the periodic signal supplied by the oscillator 3 , a pulse width modulated signal S (T _{on 1} ), S (T _on2 ) and S (T _on3 ) whose peak intensity is I _c and whose activation time is respectively T _on1 , T _on2 and T _on3 , then supplies one of the light sources 41, 42 and 43 with this signal.

There is shown in [Fig.4] two examples of signals modulated in pulse width S1 and S2, one according to the peak intensity I _C1 and the other according to the peak intensity I _C2 .

Each of these signals SI and S2 is a periodic signal of period TP WM and having, over each period, a pulse formed by a rising ramp, of duration T _r , towards the peak intensity value I _C1 , respectively I _C2 , which is maintained for an activation time T ₁ , respectively T ₂ , and followed by a downward ramp, of duration T _f , towards a zero value. It should be noted that the mean intensities of these signals S1 and S2, corresponding substantially to the hatched areas, are distinct. In fact, due to the difference in the efficiency of the light sources for the two peak intensities that can be selected, the sources being more efficient for the high peak intensities, it is necessary to adapt the current supplied to these sources as a function of of the selected peak intensity. It should be noted that, when the received instruction I requires a particularly low overall luminous flux or else a color such that the target luminous flux for one of the sources is particularly low, for the S2 type signal, the time of activation T ₂ may be of the order of the rise times T _r and fall times T _f , or even be less than them. In this case, it is impossible to obtain an average intensity of the signal actually generated which corresponds substantially to that determined. In addition, the chromatic behavior of sources during rise and fall times is unpredictable. The invention thus allows the generators to generate an SI type signal, the activation time being in this case appreciably longer than the rise times T _r and fall times T _f so that the average intensity of the signal actually generated corresponds appreciably to that determined . Furthermore, in this case, the chromatic impact of the rise and fall times is minimized.

[0048] There is shown in [fig.5] a lighting system S according to a second embodiment of the invention, the system S forming a lighting system for the interior of a motor vehicle.

For this purpose, the system S comprises a controller 1, a first light unit 4 comprising three light sources 41, 42, 43 and a second light unit 5 comprising three light sources 51, 52 and 53.

Each of the light sources 41, 42 and 43 is a semiconductor chip capable of emitting a light beam of red, green and blue color respectively. These three light sources are arranged in the vicinity of one another to form a 4 RGB light emitting diode. Likewise, each of the light sources 51, 52 and 53 is a semiconductor chip capable of emitting a light beam of red, green and blue color respectively. These three light sources are arranged in the vicinity of each other to form a 5 RGB light emitting diode.

Equivalent to the first embodiment, the controller 1 is arranged to receive, for example from a central computer of the motor vehicle, emission instructions I requiring the emission by the RGB light-emitting diodes 4 and 5 of a light beam of a given color C and of a given _{overall luminous flux Y G.}

For this purpose, the controller 1 comprises computers 11, 12 and 13, three generators 21, 22, 23 of pulse width modulated signals and an oscillator 3 arranged to implement together the described steps E0 to E4 in [fig.2].

However, unlike [fig.1] and [fig.2], the controller 1 comprises a switching unit 6 arranged so that the generators 21, 22 and 23 provide said signals modulated in width d pulse to the light sources of the RGB light emitting diodes 4 and 5 in a multiplexed fashion.

The controller 1 has two inputs Inl and In2, each connected in a common way to the anodes of the light sources 41, 42 and 43, respectively 51, 52 and 53, of each RGB light-emitting diodes 4 and 5. Each input Inl and In2 can be activated or deactivated selectively by the switching unit 6 so as to allow the passage of a current through the RGB diode to which it is connected.

The controller 1 has three outputs Out1, Out2 and Out3. Each output is connected in a common way to the cathodes of the light sources of the RGB diodes 4 and 5 which are able to emit a light beam of the same color. In particular, the output Out1 is connected to the cathodes of the light sources 41 and 51, the output Out2 is connected to the cathodes of the light sources 42 and 52 and the output Out3 is connected to the cathodes of the light sources 43 and 53. Each output Out1, Out2 and Out3 is also connected to one of the generators to receive a pulse width modulated signal supplied by this generator and to transmit it to the light sources to which it is connected.

The switching unit 6 periodically and alternately controls the activation and deactivation of inputs Inl and In2 so that, when one is activated, the other is deactivated. Thus, generators 11, 12 and 13 provide pulse width modulated signals alternately to RGB diode 4 and RGB diode 5.

The switching unit also synchronously controls the computers 11, 12 and 13 so that the implementation of steps El to E4 is adapted to the RGB diode connected to the activated input. In particular, the switching unit controls the computers 11, 12 and 13 so that the duty cycles are determined according to the efficiencies of the light sources of the RGB diode connected to the activated input.

Provision can be made, without departing from the scope of the invention, that the light system S comprises more than two RGB light-emitting diodes arranged in different places of the passenger compartment of the motor vehicle and to which signals modulated in width of pulse in a multiplexed fashion.

It should be noted that in the examples which have been described, all of the calculators of the controller 1 can be produced by the same component, for example of the integrated circuit type.

The above description clearly explains how the invention makes it possible to achieve the objectives that it has set itself, namely to maintain precision in controlling the light flux and / or the color of a light beam emitted. by a light source of a light system of a motor vehicle which is satisfactory, including when it is required a low luminous flux or a small variation of the luminous flux, by proposing a method of control of the luminous system which allows to generate pulse width modulated signals the peak intensity of which is suited to this required luminous flux.

In any event, the invention cannot be limited to the embodiments specifically described in this document, and extends in particular to all equivalent means and to any technically operative combination of these means. In particular, it is possible to envisage using the method and the lighting system described for other areas of automotive lighting than that described, such as for example for road lighting or for light signaling. It is also possible to envisage other modes of selecting the value of the peak intensity, and in particular of selecting peak intensity values which are different from one light source to another.

Claims

[Claim 1] A method of controlling a light system (S) of a motor vehicle comprising:

• a pulse width modulated signal generator (21, 22, 23), the generator being able to generate a pulse width modulated signal (SI, S2) having a first peak intensity (I _c1 ) or a second peak intensity greater than the first peak intensity (I _c2 ), and

• a light source (41, 42, 43) arranged to emit a light beam according to a light flux determined as a function of said pulse width modulated signal, characterized in that it comprises the following steps:

• Receipt of an instruction (I) to emit a light beam by the light source according to a given target light flux (Y _G );

• (El) Selection of a peak intensity (I _c ) among the first and second peak intensities as a function of the given target luminous flux;

• (E2, E3) Determination of a setpoint duty cycle (T "a, T _on2 , T _on3 ) of a pulse width modulated signal having the selected peak intensity as a function of the given target luminous flux and of the efficiency of the light source; and

• (E4) Generating a modulated reference signal S pulse width (T _on1), S (T _on2), S (T _on3)) having the selected peak intensity and the determined setpoint duty cycle and providing to the light source of said pulse width modulated reference signal.

[Claim 2] Method according to the preceding claim, the light system (S) comprising three light sources (41, 42, 43), each source being able to emit a light beam of a predetermined color, in which the step of receiving of a transmission instruction (I) comprises the reception of an instruction to transmit a light beam by the light system according to a given color (C) and a light flux global given (Y _G ).

[Claim 3] The method according to the preceding claim, the method comprising a step (E21, E22, E23, E31, E32, E33) of determining a target duty cycle (T _on1, T _on2, T _on3), a step (E41, E42, E43) for generating and supplying a setpoint signal (S (T _on1 ), S (T _on2 ), S (T _on3 )) for each of the light sources (41, 42, 43 ) of the lighting system (S).

[Claim 4] The method according to the preceding claim, wherein, for each light source (41, 42, 43), the set duty ratio (T _on1, _on2 T, T _on3) is determined so that the color and flow light of the sum of the light beams emitted by the three light sources correspond substantially to the given color (C) and to the given overall luminous flux (Y _G ).

[Claim 5] Method according to one of claims 2 to 4, in which the step of selecting (El) the peak intensity (I _c ) is common for all the light sources (41, 42, 43) of the system. luminous (S).

[Claim 6] Method according to the preceding claim, in which the step of selecting (El) the peak intensity (I _c ) comprises the comparison of the overall luminous flux (Y _G ) given with a predetermined threshold value (Y _s ) , the first peak intensity (I _C1 ) being selected if the overall luminous flux is less than said threshold value and the second peak intensity (I _C2 ) being selected if the overall luminous flux is greater than said threshold value.

[Claim 7] A method according to claim 4, the method comprising a step of determining a given target light intensity for each of the light sources (41, 42, 43) of the light system (1) from said color (C) and global luminous flux (Y _G ) given, in which the step of selecting (El) the peak intensity (I _c ) comprises the comparison of the smallest value of the target luminous fluxes determined for each of the light sources with a predetermined threshold value (Y _s ), the first peak intensity (I _C1 ) being selected if said smallest value is less than said threshold value and the second peak intensity (I _C2 ) being selected if said smallest value is greater than said value threshold.

[Claim 8] Method according to one of the preceding claims, the three light sources (41, 42, 43) forming a first light unit (4) of the light system (S), and the light system comprising a second light unit (5) comprising three light sources (51, 52, 53) each capable of emitting a light beam of a predetermined color; the method comprising a step (E2, E3) of determining a target duty cycle (T _on1, _on2 T _on3 T) and a step (E4) for generating and supplying a reference signal (S (T _on1 ), S (T _on2 ), S (T o _n3 )) for each of the light sources of each of the light units of the lighting system, characterized in that the steps of providing a reference signal for the light sources of each light unit in the lighting system are temporally multiplexed.

[Claim 9] Method according to the preceding claim, the lighting system (S) comprising a single controller (1) comprising three generators (21, 22, 23) of signals modulated in pulse width, each generator being intended to generate a signal. setpoint (S (T _on1 ), S (T _on2 ), S (T _on3 )) and to supply this setpoint signal to one of the light sources of each light unit.

[Claim 10] Light system (S) of a motor vehicle, comprising at least one pulse width modulated signal generator (21, 22, 23) and a light source (41, 42, 43) arranged to emit a signal. light beam according to a light flux determined as a function of said pulse width modulated signal; the lighting system being arranged to implement the method according to one of the preceding claims.

[Claim 11] A light system (S) according to the preceding claim, the light system being a system for lighting the interior of the motor vehicle.