EP3616471B1 - Method and system for controlling the electric current within a semiconductor light source defining at least two distinct light emission regions - Google Patents

Description

The present invention relates to the field of light methods and assemblies comprising a system for controlling an electric current within a semiconductor light source provided with a substrate. In particular, the present invention relates to a method for controlling an electric current within a semiconductor light source as defined by claim 1, a light assembly as defined by claim 4, and light device vehicle comprising at least one such light assembly.

A method of controlling an electric current within a semiconductor light source provided with a substrate, making it possible to modify the luminous flux of the light source, is known. Such a process is disclosed in the document WO2017/025441 A1 .

The method is implemented by a control system comprising a member for adjusting the average value of an electrical quantity relating to the electric current received by the light source, as well as a device for connecting the light source to the member adjustment. The electrical quantity is for example the voltage, intensity or electrical power of the electric current. Such a method comprises a step consisting of adjusting, via the adjustment member, the average value of the electrical quantity relating to the electrical current received by the light source as a function of a setpoint of current, electrical voltage or average electrical power (born). Setpoint current, electrical voltage or average electrical power then corresponds to the desired luminous flux for the light source.

However, a disadvantage of such a method of controlling a current is that it does not make it possible to obtain high luminous flux dynamics. Indeed, the adjustment member is generally a chopper connected to a switching power supply, and the adjustment carried out by the chopper is a pulse width modulation type regulation. However, the minimum duty cycle of this regulation, below which one must not go below without seriously harming the precision of current control, is generally between 5 and 7%. More precisely, if the duty cycle applied during this regulation by pulse width modulation is less than the value of 5%, “soft” fronts may appear in the control of the electrical quantity relating to the electric current received by the light source. Such “soft” fronts, which can go as far as triangular aliasing instead of the recommended rectangular aliasing, harm the precision of current control, and introduce significant losses in efficiency, or even electromagnetic compatibility problems within the system. . In fact, the tolerance on the width of the pulse is absolute and does not depend on this width. In other words, when this width decreases the tolerance is increasingly important in relative terms.

This proves particularly problematic in the case where the light source is intended to be used according to several functions each presenting a distinct luminous flux value, and where the ratio between the extreme values of the fluxes is in particular greater than or equal to 20. In this Indeed, the minimum duty cycle that should be applied during pulse width modulation regulation to achieve such flow dynamics should be less than or equal to 5%. Such a situation is for example known in the field of vehicles, when the light source is intended to be used both in a “daytime running light” function and in a “position light” function.

In order to resolve the aforementioned drawback, a known solution consists of adding a resistance to the control system previously described, and connecting this resistance in series with the light source whose current we are trying to control. The value of this resistance is chosen so as to allow thermal dissipation of the energy linked to “soft” fronts. However, such a solution is extremely expensive, due to the cost of such resistance. Furthermore, such a resistance does not make it possible to improve the precision of current control.

The technical problem that the invention aims to solve is therefore to propose a method and a system for controlling an electric current within a semiconductor light source provided with a substrate, making it possible to increase the dynamics of flow of the source, in particular to obtain a ratio between the extreme flux values greater than or equal to 100, and this in a simple manner, at reduced cost, and without loss of efficiency or electromagnetic disturbance in the system.

For this purpose, a first object of the invention is a method of controlling an electric current within a semiconductor light source as defined in claim 1.

Thanks to the fact that the light source defines on its substrate at least two selectively activatable light emission zones, it is possible to adjust separately and independently, via the adjustment member, the luminous flux values associated respectively with each of the zones d light emission. It is thus possible, via this setting as well as the addition or selective activation of luminous zones, to obtain a greater range of adjustment of the luminous flux, without sacrificing the precision of current control, nor causing problems of efficiency or electromagnetic compatibility at the within the system. Furthermore, this increase in the adjustment range of possible values for the luminous flux is obtained without modification of the other physical characteristics of the light source, such as the hue for example. Furthermore, the control method according to the invention uses only one adjustment member, this member being a conventional adjustment member. Thus, the control method according to the invention makes it possible to increase the flow dynamics of the light source, in a simple manner, at reduced cost, and without loss of efficiency or electromagnetic disturbance in the system.

The control method according to the invention may optionally present one or more of the characteristics defined by dependent claims 2 to 3.

The invention also relates to a light assembly as defined by claim 4.

The light assembly according to the invention may optionally have one or more of the characteristics defined in dependent claims 5 to 8.

According to the embodiment of the invention, the light source comprises a plurality of photo-emitting elements, the photo-emitting elements being distributed into several groups of distinct photo-emitting elements, each group of photo-emitting elements corresponding to one of said light zones, the photo-emitting elements of the groups corresponding to said at least two light emitting zones being interleaved so that said groups of photo-emitting elements form interlaced matrices of discrete photo-emitting elements.

This embodiment of the invention advantageously makes it possible to maintain an almost uniform appearance in the visual rendering of the light source, whatever the value of the luminous flux emitted by this source.

In a particular embodiment of the invention, the vehicle lighting device according to the invention is a road lighting device, in particular a projector, or a signaling device, in particular a traffic light, or a signaling device. lighting of a vehicle interior.

The invention also relates to a vehicle comprising at least one vehicle lighting device as described above.

• La figure 1 est une représentation schématique d'un dispositif lumineux de véhicule muni d'un ensemble lumineux, l'ensemble lumineux comprenant une source lumineuse et un système de pilotage d'un courant électrique selon l'invention ;
• La figure 2 est une vue en perspective de la source lumineuse de la figure 1 selon un premier mode de réalisation ;
• La figure 3 est une vue analogue à celle de la figure 2 selon un deuxième mode de réalisation de la source lumineuse ;
• La figure 4 un organigramme représentant le procédé de pilotage d'un courant électrique selon l'invention, mis en œuvre par le système de pilotage de la figure 1 ;
• La figure 5 est un ensemble de trois diagrammes représentant chacun l'évolution d'un rapport cyclique d'application d'une tension électrique d'entrée aux bornes d'une zone lumineuse de la source lumineuse, telle que représentée sur la figure 3, en fonction du flux lumineux total émis par la source lumineuse.

Other characteristics and advantages of the invention will appear on reading the detailed description of the non-limiting examples which follow, for an understanding of which reference will be made to the appended drawings, among which:

• There figure 1 is a schematic representation of a vehicle lighting device provided with a light assembly, the light assembly comprising a light source and a system for controlling an electric current according to the invention;
• There figure 2 is a perspective view of the light source of the figure 1 according to a first embodiment;
• There Figure 3 is a view analogous to that of the figure 2 according to a second embodiment of the light source;
• There Figure 4 a flowchart representing the method of controlling an electric current according to the invention, implemented by the control system of the figure 1 ;
• There Figure 5 is a set of three diagrams each representing the evolution of a cyclical ratio of application of an electrical input voltage to the terminals of a light zone of the light source, as represented on the Figure 3 , depending on the total luminous flux emitted by the light source.

There figure 1 illustrates a vehicle lighting device 10, comprising a lighting assembly 12. The lighting device 10 is for example a road lighting device, in particular a projector. In a variant not shown, the light device 10 is a signaling device, in particular a traffic light. In another variant not shown, the light device 10 is a vehicle passenger compartment lighting device.

The light assembly 12 comprises a semiconductor light source 13, and a system 16 for controlling an electric current within the light source 13. The light assembly 12 also comprises an optical module, such a module does not not being shown in the figures for reasons of clarity.

As illustrated on the figure 2 And 3 , the light source 13 comprises a substrate 18 and defines, on its substrate 18, at least two distinct light emission zones 20. The substrate 18 is for example essentially composed of silicon.

In the embodiment of the invention shown in the figure 2 , the light source 13 further comprises several photo-emitting elements 22. The photo-emitting elements 22 are distributed into several groups 24A, 24B, 24C of elements separate photoemitters. Each group 24A, 24B, 24C of photoemitting elements 22 corresponds to one of the distinct light emission zones 20. Thus, in the particular embodiment illustrated in the figure 2 , the photoemitting elements 22 are distributed into three groups 24A, 24B, 24C of distinct photoemitting elements, and the light source 13 defines on its substrate 18 three corresponding light emission zones 20A, 20B, 20C.

As illustrated on the figure 2 , the photoemitting elements 22 of the groups 24A, 24B, 24C are interleaved so that these groups 24A, 24B, 24C of photoemitting elements form interlaced matrices of discrete photoemitting elements 22. By “matrix of discrete photoemitting elements” , we mean a network of photo-emitting elements interconnected and forming a group of discrete photo-emitting elements, whether this network is regular or not.

Preferably, each photoemitting element 22 comprises at least one electroluminescent rod 26. In a particular embodiment illustrated in the figure 2 , each light-emitting element 22 comprises at least one electroluminescent rod 26 and one photoluminescent element 28. Preferably, each light-emitting element 22 comprises several electroluminescent rods 26 and one photoluminescent element 28. The electroluminescent rods 26 are thus distributed into several groups of electroluminescent rods 26 , each group corresponding here to a photoemitting element 22. Preferably, the electroluminescent rods 26 within the same photoemitting element 22 are electrically connected to each other. More preferably, the electroluminescent rods 26 within the same photoemitting element 22 are electrically connected in parallel.

Each electroluminescent rod 26 extends from the substrate 18. Preferably, each electroluminescent rod 26 has submillimeter dimensions. Each stick electroluminescent 26 extends for example in a preferred direction from the substrate 18. Preferably, the electroluminescent rods 26 of the light source 13 extend in the same preferred direction from the substrate 18. Each electroluminescent rod 26 comprises for example a nitride of metal, in particular gallium nitride.

Each photoluminescent element 28 is for example formed of a layer of photoluminescent material. Each photoluminescent element 28 designates a light converter comprising at least one luminescent material designed to absorb at least a portion of at least one excitation light emitted by a light source and to convert at least a portion of said absorbed excitation light into emission light having a wavelength different from that of the excitation light. In the case of yellow light, the material of the photoluminescent element is for example one of the following components: Y ₃ A ₁₅ O ₁₂ :Ce ³⁺ (YAG), (Sr,Ba) ₂ SiO ₄ :Eu ²⁺ , Ca _x (Si,Al) ₁₂ (O,N) ₁₆ :Eu ²⁺

As a variant of this embodiment of the invention illustrated in the figure 2 , and not covered by the set of claims, the light source 13 is a two-dimensional monolithic source, for example of the two-dimensional monolithic light-emitting diode type, and each photoemitting element 22 is an element of this monolithic source. The photo-emitting elements are distributed into several groups of distinct photo-emitting elements on this source, each group corresponding to one of the distinct light emission zones. The light emitting elements of the groups are interleaved such that these groups of light emitting elements form interleaved arrays of discrete light emitting elements. This is the case where the photoemitting elements take the form of a pad. In an exemplary embodiment, the light is emitted from the top of the pads.

There Figure 3 represents the light source 13, according to a second embodiment of the invention, alternative to the embodiment illustrated in the figure 2 . In this second embodiment, the light source 13 defines on its substrate 18 several concentric light emission zones 20D, 20E, 20F. In the particular embodiment illustrated on the Figure 3 , the light source 13 defines on its substrate 18 three concentric light emission zones: a first light emission zone 20D, a second light emission zone 20E surrounding the first zone 20D, and a third light emission zone 20F surrounding the second zone 20E. For example, when the first light emission zone 20D is activated, the light source 13 is used in the vehicle according to a “position light” function; when at least the second light zone 20E is activated, the light source 13 is used in the vehicle according to a “daytime running light” function; and when at least the third light zone 20F is activated, the light source 13 is used in the vehicle according to a “high beam” function.

Preferably, as illustrated in the Figure 3 , the light source 13 comprises several electroluminescent rods 26. The electroluminescent rods 26 are thus distributed into several groups 29D, 29E, 29F of electroluminescent rods 26, each group corresponding to one of the light emission zones 20D, 20E, 20F. Preferably, the electroluminescent sticks 26 within the same group 29D, 29E, 29F are electrically connected to each other. More preferably, the electroluminescent sticks 26 within the same group 29D, 29E, 29F are electrically connected in parallel.

Each electroluminescent rod 26 extends from the substrate 18. Preferably, each electroluminescent rod 26 has submillimeter dimensions. Each electroluminescent stick 26 extends for example in one direction privileged from the substrate 18. Preferably, the electroluminescent rods 26 of the light source 13 extend in the same preferred direction from the substrate 18. Each electroluminescent rod 26 comprises for example a metal nitride, in particular a gallium nitride.

As a variant of this embodiment of the invention illustrated in the Figure 3 , and not covered by the set of claims, the light source 13 according to this second embodiment is a high definition light source. By “high definition light source” is meant a light source comprising a high number, typically greater than or equal to 1000, of electroluminescent elements capable of being powered separately.

The light source 13 according to this second embodiment defines on its substrate two concentric light emission zones: a first light emission zone and a second light emission zone surrounding the first zone. Preferably, according to this exemplary embodiment, the surface of the second light emission zone is greater than that of the first light emission zone, for example such that the ratio between this surface and the surface of the first light emission zone light emission is greater than or equal to 9, and is preferably greater than or equal to 10. Alternatively or in addition, when the light source 13 further comprises several electroluminescent rods distributed into groups of rods, the density of the electroluminescent rods of the group corresponding to the second light emission zone is greater than that of the group corresponding to the first light emission zone, for example such that the ratio between this density and the density of the electroluminescent rods of the group corresponding to the first light emission zone is greater than or equal to 9, and is preferably greater than or equal to 10.

Returning to the figure 1 , the control system 16 comprises a member 30 for adjusting the average value of an electrical quantity relating to the electric current received by the light source 13, and a device 32 for connecting the light source 13 to the adjustment member 30 Preferably, the control system 16 further comprises a member 34 for measuring an electrical quantity relating to an electric current circulating within the light source 13.

The connection device 32 is connected to the distinct light emission zones 20 of the light source 13 and is capable of selectively activating these light emission zones 20, as illustrated in the figure 2 And 3 .

As shown on the figure 1 , the connection device 32 comprises for example a semiconductor electronic switching component 38, such as a transistor for example. The electronic component 38 comprises two conduction electrodes and a control electrode, not shown in the figures for reasons of clarity. One of the conduction electrodes forms, for example, a 40A negative terminal. The other conduction electrode is for example capable of being connected to one or more positive terminals 40B. In the embodiments of the light source 13 illustrated on the figure 2 And 3 , the negative terminal 40A is connected to a cathode 42A arranged on the substrate 18. In the embodiment illustrated on the figure 2 , each positive terminal 40B is connected to anodes 42B belonging to the same group 24A, 24B, 24C of photoemitting elements, each anode 42B being arranged on a photoemitting element 22. More precisely, each anode 42B is for example formed by a layer conductive deposited above the substrate 18, on the side of the rods 26 of the photoemitting element 22 on which the anode 42B is arranged. Preferably, each anode 42B electrically joins the rods 26 of the photoemitting element 22 on which it is arranged. In the embodiment illustrated on the Figure 3 , each positive terminal 40B is connected to an anode 43B arranged within a group 29D, 29E, 29F of electroluminescent sticks 26. More precisely, each anode 43B is for example formed by a conductive layer deposited above the substrate 18, on the side of the sticks 26 of the group 29D, 29E, 29F within which the anode 43B is arranged. Preferably, each anode 43B electrically joins the rods 26 of the group 29D, 29E, 29F within which it is arranged.

The control electrode is able to receive a signal 44 for controlling activation of one of the light emission zones 20.

The adjustment member 30 is connected to a source 36 of supplying current or electrical input voltage, in particular direct current or electrical input voltage. The power source 36 is for example arranged within the light assembly 12. Alternatively, the power source 36 is arranged within the vehicle and forms for example the vehicle battery. In this case, the power source 36 is for example connected via a distributor, also located within the vehicle. In the particular embodiment illustrated on the figure 1 , the power source 36 is a DC input electrical voltage supply source, providing a substantially constant input electrical voltage U ₀ .

The adjustment member 30 is configured to adjust, for each activated light zone 20, the average value of the electrical quantity relating to the electric current received by the light source 13, as a function of a current setpoint 46A, 46B, 46C, of electrical voltage or average electrical power associated with this activation. The current, electrical voltage or average electrical power setpoint 46A, 46B, 46C is for example stored in a memory internal or external to the light device 10, not shown in the figures. The setpoint 46A, 46B, 46C can be dynamically updated in the memory, in particular as a function of the temperature, by a control module connected to the memory. Such a control module is not shown in the figures for reasons of clarity.

In the embodiment of the invention illustrated in the figure 1 , the adjustment member 30 is a chopper capable of supplying an electrical output current intended to circulate within the light source 13. According to this embodiment, the electrical quantity to be adjusted is the electrical voltage, and the adjustment member setting 30 is configured to adjust the average value of the output voltage U1 as a function of an average current setpoint 46A, 46B, 46C. Preferably, the chopper forming the adjustment member 30 has a switching frequency of between 50 Hz and 1 kHz, preferably between 200 Hz and 1 kHz so that the human eye does not distinguish oscillations, more preferably substantially equal to 400 Hz.

According to the particular embodiment illustrated on the figure 1 , the control system 16 implements a voltage supply and current control of the light source 13.

The measuring member 34 is connected to the adjusting member 30. The measuring member 34 is capable of providing at least one Ism data measurement of an electrical quantity relating to the electric current received by the light source 13. According to the particular embodiment of the figure 1 , the measured electrical quantity is an electric current, and the measuring member 34 is able to provide Ism data measuring the average value of the electric current received by the light source 13. Thus, the adjusting member 30 is advantageously configured to regulate, for each activated light zone 20, the average value of the electrical output current as a function of the value of measurement data Ism supplied by the measuring device 34, and of the average current setpoint 46A, 46B, 46C.

The measuring member 34 comprises for example a resistor 48, connected in series with the light source 13, and a signal amplification module 50 intended to amplify the voltage value taken by the resistor 48.

In an embodiment not shown, the control system can be integrated, that is to say mounted, on the light source. In this case, the control unit may further comprise a central processing unit coupled with a memory on which a computer program is stored which includes instructions allowing the processor to carry out steps generating signals allowing control of the light source. The control unit can be an integrated circuit, for example an ASIC (acronym for “Application-Specific Integrated Circuit”) or an ASSP (acronym for “Application Specific Standard Product”).

The method of controlling an electric current according to the invention, implemented by the control system 16, will now be described with reference to the Figure 4 .

During an initial step 60, the control system 16 receives a control signal for activation of a first light emission zone 20A; 20D of the light source 13. The connection device 32 then receives a corresponding activation control signal 44, and consequently activates the first light emission zone 20A; 20D.

During a following step 62, the adjustment member 30 adjusts the average value of the electrical output voltage U1 which it supplies to the light source 13, as a function of a first average current setpoint 46A. A first value of a first luminous flux is thus obtained for the light source 13. This first luminous flux corresponds to the flux emitted by the first light emission zone 20A; 20D. According to the embodiment of the invention illustrated on the figure 1 , the chopper forming the adjustment member 30 regulates the average value of the electric current which it supplies to the light source 13, by modifying the cyclical ratio of application of the input electric voltage U ₀ to the terminals of the first zone bright 20A; 20D. During this adjustment step 62, the duty cycle, modified by the chopper, however remains greater than a value equal to 5%.

In the preferred embodiment according to which the control system 16 further comprises a measuring member 34, the adjustment step 62 comprises a first sub-step of measuring, by the measuring member 34, the average current received by the light source 13; and a second sub-step of supplying, by the measuring member 34 to the adjusting member 30, data Ism measuring this average current. The chopper forming the adjustment member 30 then regulates the average value of the output electric current as a function of the value of the average current measurement data Ism provided by the measuring member 34, and of the first current setpoint 46A AVERAGE.

During a following step 64, the control system 16 receives a control signal for activation of a second light emission zone 20B; 20E of the light source 13. The connection device 32 then receives a corresponding activation control signal 44, and consequently activates the second light emission zone 20B; 20E.

During a following step 66, the adjustment member 30 adjusts the average value of the electrical output voltage U1 which it supplies to the light source 13, as a function of a second average current setpoint 46B. A second value of a second luminous flux is thus obtained for the light source 13. This second luminous flux corresponds to the flux emitted by at least the second light emission zone 20B; 20E. Indeed, according to a first example of implementation of the method, the second luminous flux corresponds to the flux emitted by the first light emission zone 20A; 20D and by the second light emission zone 20B; 20E. Alternatively, the second light flux corresponds to the flux emitted only by the second light emission zone 20B; 20E. In this case, the method comprises, prior to step 66, an additional step of deactivating the first light emission zone 20A; 20D by the connection device 32. According to the preferred embodiment illustrated on the figure 1 , the chopper forming the adjustment member 30 regulates the average value of the electric current which it supplies to the light source 13, by modifying the cyclical ratio of application of the input electric voltage U ₀ to the terminals by at least the second light zone 20B; 20E. During this adjustment step 66, the duty cycle, modified by the chopper, however remains greater than a value equal to 5%.

During the adjustment step 66, the adjustment member 30 adjusts the average value of the electrical output voltage U1 which it supplies to the light source 13, so that the ratio between the second value of the second flux luminous flux obtained at the end of this step 66, and the first value of the first luminous flux obtained at the end of the adjustment step 64 is greater than or equal to 100, and preferably between 100 and 1000. To obtain a ratio value equal to 1000, the duty cycle value must be greater than 5%, and

it is possible to play on the first and second concentric light emission zones, so that the ratio between the surfaces of these zones and/or between the densities of electroluminescent sticks of these zones is equal to 50.

Preferably, the method further comprises a following step 68 during which the control system 16 receives a control signal for activation of a third light emission zone 20C; 20F of the light source 13. The connection device 32 then receives a control signal corresponding activation 44, and consequently activates the third light emission zone 20C; 20F.

Still preferably, during a following step 70, the adjustment member 30 adjusts the average value of the electrical output voltage U1 which it supplies to the light source 13, as a function of a third current setpoint 46C AVERAGE. A third value of a third luminous flux is thus obtained for the light source 13. This third luminous flux corresponds to the flux emitted by at least the third light emission zone 20C; 20F. Indeed, according to a first example of implementation of the method, the third light flux corresponds to the flux emitted by the first light emission zone 20A; 20D, by the second light emission zone 20B; 20E and by the third light emission zone 20C; 20F. Alternatively, the third light flux corresponds to the flux emitted by one of the first and second light emission zones 20A, 20B; 20D, 20E and by the third light emission zone 20C; 20F, or to the flux emitted only by the third light emission zone 20C; 20F. In this case, the method comprises, prior to step 70, an additional step of deactivation of the first light emission zone 20A; 20D and/or the second light emission zone 20B; 20E by the connection device 32. According to the preferred embodiment illustrated on the figure 1 , the chopper forming the adjustment member 30 regulates the average value of the electric current which it supplies to the light source 13, by modifying the cyclical ratio of application of the input electric voltage U ₀ to the terminals by at least the third light zone 20C; 20F. During this adjustment step 70, the duty cycle, modified by the chopper, however remains greater than a value equal to 5%.

Preferably, during the adjustment step 70, the adjustment member 30 adjusts the average value of the electrical voltage of output U1 which it supplies to the light source 13, so that the ratio between the third value of the third luminous flux obtained at the end of this step 70, and the second value of the second luminous flux obtained at the end from adjustment step 66 is greater than or equal to 4, and preferably between 4 and 100; and that the ratio between the second value of the second luminous flux obtained at the end of the adjustment step 66, and the first value of the first luminous flux obtained at the end of the adjustment step 64 is greater or equal to 3, and preferably between 3 and 30.

The adjustment carried out by the chopper forming the adjustment member 30 during the adjustment steps 62, 66, 70 is a pulse width modulation type regulation.

There Figure 5 is an example of controlling the duty cycle of application of the input electrical voltage U ₀ , illustrating steps 60 to 70 of the method of controlling a current described above, for a light source 13 according to the example of particular achievement represented on the Figure 3 . More precisely, the Figure 5 is a set of three diagrams 72D, 72E, 72F each representing the evolution of the cyclic ratio R of application of the input electrical voltage U ₀ to the terminals respectively of one of the light zones 20D, 20E, 20F, as a function of the total luminous flux Φ emitted by the light source 13. It is assumed for example that the maximum luminous flux emitted by the third light emission zone 20F is greater than the maximum luminous flux emitted by the second light emission zone 20E, which is -even greater than the maximum luminous flux emitted by the first light emission zone 20D.

Initially, the total luminous flux Φ emitted by the light source 13 has for example a minimum value Φ _min .

During the initial step 60, the connection device 32 activates the first light emission zone 20D, as shown in diagram 72D. The duty cycle R of application of the input electrical voltage U ₀ across the first light zone 20D has for example a minimum value R _min .

During the next step 62, the adjustment member 30 regulates the average value of the electrical output voltage U1 which it supplies to the light source 13, by modifying the cyclical ratio R of application of the electrical voltage d input U ₀ across the first light zone 20D. This regulation is done by progressive increase in the duty cycle R between the minimum value R _min and a maximum value R _max , as illustrated in diagram 72D. The R _min value is greater than a value equal to 5%, and the R _max value is for example substantially equal to 100%.

avec Φ_{min 20D}, respectivement Φ_{min 20E}, la valeur du flux lumineux émis par la première zone lumineuse 20D, respectivement par la deuxième zone lumineuse 20E, lorsque le rapport cyclique R présente sa valeur minimale R_min.During the next step 64, the connection device 32 activates the second light emission zone 20E, as illustrated in diagram 72E. The duty cycle R of application of the input electrical voltage U ₀ across the second light zone 20E has for example a minimum value R _min . During this step 64, in order to ensure continuity in the total luminous flux Φ emitted by the light source 13, the cyclic ratio R of application of the input electrical voltage U ₀ across the first light zone 20D is switched from its maximum value R _max to its minimum value R _min . For this continuity of total luminous flux to be obtained, the following condition must be verified: $$\left({\mathrm{R}}_{\max }-{\mathrm{R}}_{\min }\right).{\mathrm{<figure-callout\; id="20D"\; label="\Phi \; min"\; filenames="imgf0002.png"\; state="\{\{state\}\}">\Phi </figure-callout>}}_{\min }={\mathrm{R}}_{\min }.{\mathrm{<figure-callout\; id="20E"\; label="\Phi \; min"\; filenames="imgf0002.png"\; state="\{\{state\}\}">\Phi </figure-callout>}}_{\min };$$

with Φ _{min 20D} , respectively Φ _{min 20E} , the value of the luminous flux emitted by the first light zone 20D, respectively by the second light zone 20E, when the duty cycle R presents its minimum value R _min .

During the next step 66, the adjustment member 30 regulates the average value of the electrical output voltage U1 which it supplies to the light source 13, by modifying the cyclic ratio R of application of the electrical voltage d input U ₀ across the first and second light zones 20D, 20E. This regulation is done by progressive increase of the duty cycle R between the minimum value R _min and the maximum value R _max , as illustrated in diagrams 72D, 72E. As a variant not shown, in order to increase the value of the total luminous flux Φ emitted by the light source 13, it is possible to only increase the value of the cyclic ratio R across one of the light zones 20D, 20E, and to maintain constant the value of the duty cycle across the other light zone 20D, 20E. We then obtain a plateau and not a positive slope on the diagram which corresponds to this last light zone 20D, 20E.

avec Φ_{min 20D}, Φ_{min 20E}, respectivement Φ_{min 20F}, la valeur du flux lumineux émis par la première zone lumineuse 20D, par la deuxième zone lumineuse 20E, respectivement par la troisième zone lumineuse 20F, lorsque le rapport cyclique R présente sa valeur minimale R_min.During the next step 68, the connection device 32 activates the third light emission zone 20F, as illustrated in diagram 72F. The duty cycle R of application of the input electrical voltage U ₀ across the third light zone 20F has for example a minimum value R _min . During this step 68, in order to ensure continuity in the total luminous flux Φ emitted by the light source 13, the cyclic ratio R of application of the input electrical voltage U ₀ across the first light zone 20D and the cyclic ratio R of application of the input electrical voltage U ₀ across the second light zone 20E are each switched from their maximum value R _max to their minimum value R _min . For this continuity of total luminous flux to be obtained, the following condition must be verified: $$\left({\mathrm{R}}_{\max }-{\mathrm{R}}_{\min }\right).\left({\mathrm{<figure-callout\; id="20D"\; label="\Phi \; min"\; filenames="imgf0002.png"\; state="\{\{state\}\}">\Phi </figure-callout>}}_{\min }+{\mathrm{<figure-callout\; id="20E"\; label="\Phi \; min"\; filenames="imgf0002.png"\; state="\{\{state\}\}">\Phi </figure-callout>}}_{\min }\right)={\mathrm{R}}_{\min }.{\mathrm{<figure-callout\; id="20F"\; label="\Phi \; min"\; filenames="imgf0002.png"\; state="\{\{state\}\}">\Phi </figure-callout>}}_{\min };$$

with Φ _{min 20D} , Φ _{min 20E} , respectively Φ _{min 20F} , the value of the luminous flux emitted by the first light zone 20D, by the second light zone 20E, respectively by the third light zone 20F, when the cyclic ratio R presents its value minimum R _min .

During the final step 70, the adjustment member 30 regulates the average value of the electrical output voltage U1 which it supplies to the light source 13, by modifying the cyclical ratio R of application of the electrical voltage d input U ₀ across the first, second and third light zones 20D, 20E, 20F. This regulation is done by progressive increase in the duty cycle R between the minimum value R _min and the maximum value R _max , as illustrated in diagrams 72D, 72E, 70F. At the end of this final step 70, the total luminous flux Φ emitted by the light source 13 reaches a maximum value Φ _max .

More generally, a principle for controlling the duty cycle identical or similar to that described above can be implemented in the case where the light source 13 defines on its substrate a number of light emission zones greater than or equal to two. The same principle of switching the duty cycle is then implemented, in order to ensure the continuity of the total luminous flux emitted by the light source 13 at the time of activation of new light zones.

In another embodiment not shown, the values of R _min and R _max may be different from one zone of the source to another. They can also be different for a given zone, from one stage of ignition to another. The duty cycle R _max is advantageously 100%, in particular for obtaining Φ _max .

The invention is described in the above by way of example. It is understood that those skilled in the art are able to carry out different embodiments of the invention without departing from the scope of the invention.

Claims (9)

1. Method for controlling an electric current within a semiconductor light source, said light source (13) comprising a substrate (18) and a plurality of photoemitter elements (22), the photoemitter elements being divided into multiple distinct groups of photoemitter elements (24A, 24B, 24C), each group of photoemitter elements corresponding to a light-emitting region (20A, 20B, 20C),

   said light source defining, on its substrate, at least two distinct light-emitting regions (20A, 20B, 20C; 20D, 20E, 20F), said at least two light-emitting regions being concentric regions (20D, 20E, 20F) or interlaced regions (20A, 20B, 20C) such that said groups of photoemitter elements of the interlaced regions (20A, 20B, 20C) form interlaced matrices of discrete photoemitter elements,

   said method being deployed by a system (16) for controlling the electric current within the light source, said control system comprising:

   - a control component (30) for the mean value of an electrical variable relating to the electric current received by the light source, said control component being able to be connected to an electric current or an electric voltage input source, specifically for a direct current or direct voltage input, and the control component being a chopper (30), and the control executed by the chopper being control of the pulse-width modulation type;

   - said control system further comprising a device (32) for the connection of the light source to the control component, this connection device being connected to said at least two distinct light-emitting regions of the light source, and being able to selectively activate said at least two light-emitting regions, and the method comprising the following steps:

   - activating a first light-emitting region of said at least two distinct light-emitting regions (20A; 20D) of the light source,

   - regulating, via the control component, the mean value of the electrical variable relating to the electric current received by the light source as a function of a first setpoint (46A) for the mean current, the mean electric voltage or the mean electric power, so as to obtain a first value of a first luminous flux for the light source, said first luminous flux corresponding to the flux emitted by said first light-emitting region, wherein the control component regulates the mean value of said electrical variable by applying a duty cycle to the value of the electrical variable;

   - activating at least a second light-emitting region of said at least two distinct light-emitting regions (20B; 20E) of the light source,

   - regulating, via the control component, the mean value of the electrical variable relating to the electric current received by the light source as a function of a second setpoint (46B) for the mean current, the mean electric voltage or the mean power, so as to obtain a second value of a second luminous flux for the light source, said second luminous flux corresponding to the flux emitted by said second light-emitting region or by a combination of the luminous flux emitted by the first light-emitting region and the luminous flux emitted by the second light-emitting region, wherein the control component regulates the mean value of said electrical variable by applying a duty cycle to the value of the electrical variable;

   the control method being characterized in that said duty cycles are greater than a value equal to 5%, such that the first value of the first luminous flux obtained for the light source (13) and the second value of the second luminous flux obtained for the light source (13) are such that the ratio between the second value of the second luminous flux and the first value of the first luminous flux is greater than or equal to 100, and is preferably between 100 and 1000.
2. Method according to Claim 1, wherein said at least two distinct light-emitting regions are concentric regions (20D, 20E, 20F), the light source defining, on its substrate, three distinct light-emitting regions (20D, 20E, 20F), the first light-emitting region (20D) being surrounded by the second light-emitting region (20E), the second light-emitting region being surrounded by a third light-emitting region (20F), and wherein the method further comprises a step for activating the third light-emitting region, and a step for regulating, via the control component (30), the mean value of the electrical variable relating to the electric current received by the light source as a function of a third setpoint (46C) for the mean current, the mean electric voltage or the mean electric power, so as to obtain a third value of a third luminous flux for the light source, said third luminous flux corresponding to the flux emitted by at least the third light-emitting region.
3. Method according to either one of the preceding claims, wherein the control system (16) further comprises a measuring component (34) for an electrical variable representative of a current flowing within the light source (13), the control component being connected to the measuring component, said method further comprising a step for measuring an electrical variable representative of the electric current flowing within the light source, and a step for the delivery of at least one measuring datum for said electrical variable, and wherein each step for regulating the mean value of the electrical variable relating to the electric current received by the light source constitutes a regulation of said mean value, executed as a function of said measuring datum and a first, or respectively a second, setpoint for the mean current, electric voltage or electric power.
4. Lighting unit (12) comprising:

   - a semiconductor light source (13) comprising a substrate (18) and a plurality of photoemitter elements (22), the photoemitter elements being divided into multiple distinct groups of photoemitter elements (24A, 24B, 24C), each group of photoemitter elements corresponding to a light-emitting region (20A, 20B, 20C), said light source defining, on its substrate, at least two distinct light-emitting regions (20A, 20B, 20C; 20D, 20E, 20F), which are concentric regions or interlaced regions such that said groups of photoemitter elements of the interlaced regions (20A, 20B, 20C) form interlaced matrices of discrete photoemitter elements, and

   - a system (16) for controlling an electric current within said light source (13), characterized in that the system is able to deploy the method for controlling an electric current according to any one of the preceding claims,

   the system comprising:

   - a control component (30) for the mean value of an electrical variable relating to the electric current received by the light source, the control component being a chopper (30), and the control executed by the chopper being control of the pulse-width modulation type, and

   - a device (32) for the connection of the light source to the control component, this connection device being connected to said at least two distinct light-emitting regions of the light source, and being able to selectively activate said at least two distinct light-emitting regions; the control component being able to be connected to an electric current or an electric voltage input source (36), specifically for a direct current or direct voltage input,

   the lighting unit being characterized in that the control component is configured to regulate, for each activated region of said at least two distinct light-emitting regions, the mean value of the electrical variable relating to the electric current received by the light source as a function of a setpoint (46A, 46B, 46C) for the mean current, the mean electric voltage or the mean electric power associated with said activation by applying a duty cycle greater than the value of 5% to the value of the electrical variable such that the first value of the first luminous flux and the second value of the second luminous flux are such that the ratio between the second value of the second luminous flux and the first value of the first luminous flux is greater than or equal to 100, and is preferably between 100 and 1000.
5. Lighting unit (12) according to Claim 4, wherein each photoemitter element (22) comprises at least one electroluminescent rod (26) extending from the substrate (18) .
6. Lighting unit (12) according to the preceding claim, wherein the electroluminescent rods (26) are divided into a plurality of separate groups of rods, each group of rods corresponding to all or part of one of said at least two distinct light-emitting regions (20A, 20B, 20C; 20D, 20E, 20F).
7. Lighting unit (12) according to one of Claims 4 to 6, wherein said at least two distinct light-emitting regions are concentric regions (20D, 20E, 20F), the light source (13) defining, on its substrate (18), a first light-emitting region (20D), and a second light-emitting region (20E), which is distinct from the first region and which surrounds the first region, the surface area of the second light-emitting region being greater than that of the first light-emitting region, such that the ratio between the surface area thereof and the surface area of the first light-emitting region is equal to or greater than 9, and is preferably equal to or greater than 10.
8. Lighting unit according to Claim 6, wherein said at least two distinct light-emitting regions are concentric regions (20D, 20E, 20F), the light source (13) defining, on its substrate (18), a first light-emitting region (20D), and a second light-emitting region (20E), which is distinct from the first region and which surrounds the first region, the density of the electroluminescent rods (26) in the group corresponding to the second light-emitting region being greater than that of the group corresponding to the first light-emitting region, such that the ratio between the density thereof and the density of the electroluminescent rods in the group corresponding to the first light-emitting region is equal to or greater than 9, and is preferably equal to or greater than 10.
9. Lighting device for a vehicle comprising at least one lighting unit, wherein the lighting unit is in accordance with one of Claims 4 to 8.

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