EP3398410B1 - Optoelectronic circuit comprising light emitting diodes - Google Patents

Description

Field

The present description relates to an optoelectronic circuit, in particular an optoelectronic circuit comprising light emitting diodes.

Disclosure of prior art

For certain applications, it is known practice to successively activate sets of light-emitting diodes of an optoelectronic circuit. An example relates to the supply of an optoelectronic circuit comprising light-emitting diodes with an alternating voltage, in particular a sinusoidal voltage, for example the voltage of the mains.

The figure 1 represents an example of an optoelectronic circuit 10 comprising input terminals IN ₁ and IN ₂ between which an alternating voltage V _IN is applied. The optoelectronic circuit 10 further comprises a rectifier circuit 12 comprising a diode bridge 14, receiving the voltage V _IN and supplying a _{rectified voltage V ALIM} which supplies N sets in series of elementary light-emitting diodes, called global light-emitting diodes D _i , where i is an integer varying from 1 to N.

The optoelectronic circuit 10 comprises a current source 22, one terminal of which is connected to node A ₂ and the other terminal of which is connected to a node A ₃ . Circuit 10 comprises a device 24 for switching the overall light-emitting diodes D _i , i varying from 1 to N. The switching device 24 makes it possible to gradually increase the number of overall light-emitting diodes receiving the supply voltage V _ALIM during an increasing phase of the supply voltage V _ALIM and of progressively reducing the number of overall light-emitting diodes receiving the supply voltage V _ALIM during a decreasing phase of the supply voltage V _ALIM . This makes it possible to reduce the period during which no light is emitted by the optoelectronic circuit 10. By way of example, the device 24 comprises N controllable switches SW ₁ to SW _N. Each switch SW _i , i varying from 1 to N, is mounted between node A ₃ and the cathode of the overall light-emitting diode D _i and is controlled by a control module 26 as a function of signals supplied by a sensor 28.

The order of closing and opening of the switches SW _i is fixed by the structure of the optoelectronic circuit 10 and is repeated for each cycle of the supply voltage V _ALIM .

The figure 2 is a timing diagram of the supply voltage V _ALIM in the case where the alternating voltage V _IN corresponds to a sinusoidal voltage and for an example in which the optoelectronic circuit 10 comprises four global light-emitting diodes D ₁ , D ₂ , D ₃ and D ₄ . In figure 2 , there is shown, schematically, phases P ₁ , P ₂ , P ₃ and P ₄ . Phase P ₁ represents the conduction phase of the overall light-emitting diode D ₁ . Phase P ₂ represents the conduction phase of the overall light-emitting diode D ₂ . Phase P ₃ represents the conduction phase of the overall light-emitting diode D ₃ . Phase P ₄ represents the conduction phase of the overall light-emitting diode D ₄ .

A drawback of optoelectronic circuit 10 is that the duration of light emission is not the same for each overall light emitting diode. Therefore, the life of the overall light emitting diode which emits light most often may be less than the life of the overall light emitting diode which emits light least often. Furthermore, depending on the configuration of the optoelectronic circuit 10, an observer can perceive an inhomogeneity of the light power emitted by the optoelectronic circuit 10.

The figure 3 shows, partially and schematically, a top view of the optoelectronic circuit 10 comprising a zone 30 in which the overall light-emitting diodes D ₁ to D _{4 are made} and a zone 32 in which the other elements of the optoelectronic circuit 10 are made. by way of example, the overall light-emitting diodes D ₁ to D ₄ are substantially aligned and arranged next to each other. In this example arrangement, an observer can perceive, in particular when the overall light-emitting diodes are spaced apart, a light power emitted by the zone 30 of the optoelectronic circuit 10 which is greater on the side of the overall light-emitting diode D ₁ , of which the duration of light emission is greater than on the side of the overall light-emitting diode D ₄ , whose light emission duration is the smallest.

Solving this drawback by a different arrangement of the light-emitting diodes can prove to be complex. This would require, for example, to distribute the light-emitting diodes of each group evenly over the entire circuit, which would greatly complicate the connection of the light-emitting diodes to each other and would undoubtedly require the use of a circuit with several metallization levels. .

The documents EP 2,088,836 , WO 2008/001274 , WO 2015/183570 , DE 10 2010 034 347 , US 2008/258695 and US 2009/284184 each describe an optoelectronic circuit comprising distinct elementary electronic circuits linked together, each elementary electronic circuit comprising a light-emitting diode.

summary

An object of an embodiment is to overcome all or part of the drawbacks of the optoelectronic circuits described above comprising overall light-emitting diodes and a device for switching light-emitting diodes.

Another object of an embodiment is to improve the homogeneity of light emission by the optoelectronic circuit.

Another object of an embodiment is to increase the life of the overall light emitting diode which emits the light the longest.

Another object of an embodiment is to reduce the bulk of the optoelectronic circuit.

Another object of an embodiment is that the number of overall light emitting diodes of the optoelectronic circuit can be changed in a simple manner.

Another object of an embodiment is that the order of activation of the overall light emitting diodes can be changed in a simple manner.

Thus, one embodiment provides an optoelectronic circuit according to claim 1.

According to one embodiment, the integrated circuit chip of each elementary electronic circuit further comprises a communication circuit containing a modulation circuit suitable for supplying a first modulated signal and a demodulation circuit. adapted to supply a second signal by demodulation of the first signal, the control circuit of the light-emitting diode being adapted to activate or inhibit the light-emitting diode from the second signal.

According to one embodiment, each elementary electronic circuit comprises a control circuit suitable for supplying an activation or deactivation signal to the other elementary electronic circuits. The optoelectronic circuit is intended to receive a variable voltage. For each elementary electronic circuit, the control circuit of the light-emitting diode is adapted to activate or inhibit the light-emitting diode according to the activation or deactivation signal, from which it follows that the number of activated light-emitting diodes depends on the value of variable voltage.

According to one embodiment, each elementary electronic circuit comprises a current source connected to the light-emitting diode.

According to one embodiment, the integrated circuit chip of each elementary electronic circuit further comprises a circuit for detecting a master or slave state of the elementary electronic circuit when the elementary electronic circuit is in operation.

According to one embodiment, the optoelectronic circuit comprises several elementary electronic circuits connected in series.

According to one embodiment, at least one of the elementary electronic circuits, called master circuit, is suitable for transmitting data to other elementary electronic circuits, called slave circuits, so that the light-emitting diodes are activated randomly or according to a given succession.

According to one embodiment, each elementary electronic circuit further comprises a first terminal. The optoelectronic circuit comprises a sensor connected to the first terminal of one of the elementary electronic circuits, and the intensity of the current supplied by the current source of the master circuit depends on a third signal supplied by the sensor.

According to one embodiment, the optoelectronic circuit comprises several elementary electronic circuits connected in parallel.

According to one embodiment, for each elementary electronic circuit, the first signal corresponds to a modulation of the supply current of the light-emitting diode.

According to one embodiment, each elementary electronic circuit further comprises a second terminal. The second signal corresponds to a modulated current supplied by the modulation circuit to the second terminal which is different from the supply current of the light-emitting diode, or the second signal corresponds to the potential at said terminal.

According to one embodiment, the optoelectronic circuit further comprises a third terminal, the demodulation circuit being adapted to receive the second signal via the third terminal.

According to one embodiment, the third terminal of each elementary electronic circuit is connected to a conductive line via a capacitor.

According to one embodiment, each elementary electronic circuit further comprises a fourth terminal and a copying circuit connecting the third terminal and the fourth terminal and adapted to supply the demodulation circuit with a copy of the current flowing between the third and fourth terminals. .

According to one embodiment, the elementary electronic circuits are connected in series according to a succession of elementary electronic circuits. For each elementary electronic circuit, except for the elementary electronic circuits located at the ends of the succession, the fourth terminal of the elementary electronic circuit is connected to the third terminal of the preceding elementary electronic circuit of the succession.

According to one embodiment, each elementary electronic circuit comprises less than five light-emitting diodes.

Brief description of the drawings

• la figure 1, décrite précédemment, est un schéma électrique d'un exemple d'un circuit optoélectronique comprenant des diodes électroluminescentes ;
• la figure 2, décrite précédemment, est un chronogramme représentant les phases d'émission de lumière des diodes électroluminescentes du circuit optoélectronique de la figure 1 ;
• la figure 3, décrite précédemment, est une vue de dessus, partielle et schématique, d'un exemple d'agencement des éléments du circuit optoélectronique de la figure 1 ;
• la figure 4 est un schéma électrique d'un mode de réalisation d'un module d'un circuit optoélectronique comprenant des diodes électroluminescentes ;
• la figure 5 est un schéma électrique d'un mode de réalisation d'un circuit optoélectronique réalisé à partir du module représenté en figure 4 ;
• les figures 6 et 7 sont des figures analogues respectivement aux figures 4 et 5 d'un autre mode de réalisation d'un module et d'un circuit optoélectronique réalisé à partir de ce module ;
• les figures 8 et 9 sont des figures analogues respectivement aux figures 4 et 5 d'un autre mode de réalisation d'un module et d'un circuit optoélectronique réalisé à partir de ce module ;
• les figures 10 et 11 sont des figures analogues respectivement aux figures 4 et 5 d'un autre mode de réalisation d'un module et d'un circuit optoélectronique réalisé à partir de ce module ;
• la figure 12 est une figure analogue à la figure 4 d'un autre mode de réalisation d'un module d'un circuit optoélectronique comprenant des diodes électroluminescentes ; et
• les figures 13 et 14 sont des schémas électriques d'autres modes de réalisation de circuits optoélectroniques à diodes électroluminescentes.

These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments given without limitation in relation to the accompanying figures, among which:

• the figure 1 , described above, is an electrical diagram of an example of an optoelectronic circuit comprising light emitting diodes;
• the figure 2 , described previously, is a timing diagram representing the light emission phases of the electroluminescent diodes of the optoelectronic circuit of the figure 1 ;
• the figure 3 , described above, is a top view, partial and schematic, of an example of the arrangement of the elements of the optoelectronic circuit of the figure 1 ;
• the figure 4 is an electric diagram of an embodiment of a module of an optoelectronic circuit comprising light emitting diodes;
• the figure 5 is an electrical diagram of an embodiment of an optoelectronic circuit produced from the module shown in figure 4 ;
• the figures 6 and 7 are figures respectively analogous to figures 4 and 5 of another embodiment of a module and of an optoelectronic circuit produced from this module;
• the figures 8 and 9 are figures respectively analogous to figures 4 and 5 of another embodiment of a module and of an optoelectronic circuit produced from this module;
• the figures 10 and 11 are figures respectively analogous to figures 4 and 5 of another embodiment of a module and of an optoelectronic circuit produced from this module;
• the figure 12 is a figure similar to the figure 4 of another embodiment of a module of an optoelectronic circuit comprising light emitting diodes; and
• the figures 13 and 14 are electrical diagrams of other embodiments of optoelectronic circuits with light emitting diodes.

detailed description

For the sake of clarity, the same elements have been designated by the same references in the various figures and, moreover, the various figures are not drawn to scale. In the remainder of the description, unless otherwise indicated, the terms "substantially", "approximately" and "of the order of" mean "to within 10%". In addition, the term “binary signal” is used to mean a signal which alternates between a first constant state, for example a low state, denoted "0", and a second constant state, for example a high state, denoted "1". The high and low states of different binary signals of the same electronic circuit can be different. In practice, the binary signals may correspond to voltages or currents which may not be perfectly constant in the high or low state. Furthermore, in the present description, the term "connected" is used to denote a direct electrical connection, without an intermediate electronic component, for example by means of a conductive track, and the term "coupled" or the term "connected", to denote either a direct electrical connection (meaning then "connected") or a connection via one or more intermediate components (resistance, capacitor, etc.).

According to one embodiment, the optoelectronic circuit has a modular structure and comprises several modules, also called elementary electronic circuits, connected to each other. According to one embodiment, the modules are not connected to a common node connected to a source of a low reference potential, for example the ground of the optoelectronic circuit. In particular, for the majority of modules, each module is connected only to one or two other modules and has a floating mass. Each module includes a diode overall electroluminescent and electronic circuit. According to one embodiment, the overall light-emitting diode corresponds to a first integrated circuit chip and the electronic circuit corresponds to a second integrated circuit chip, the first and second chips being mounted on a printed circuit or integrated in the same package. According to one embodiment, the modules all have the same structure. This advantageously makes it possible to easily add a module to the optoelectronic circuit or to easily remove a module from the optoelectronic circuit.

According to one embodiment, for each module, the electronic circuit comprises a control circuit for the overall light-emitting diode, for example an activation / inhibition circuit for the overall light-emitting diode. The electronic circuits of the modules make it possible to activate or inhibit the overall light-emitting diodes as a function of the value of the supply voltage of the optoelectronic circuit according to a selection sequence.

According to one embodiment, the electronic circuits of the modules are adapted to communicate with each other, for example for the transmission of the selection sequence of the light-emitting diodes as a function of the supply voltage.

According to one embodiment, the modules can be connected to each other so that the overall light emitting diodes can be connected in series and / or in parallel.

Preferably, the number of light-emitting diodes which are activated varies automatically as a function of the value of the supply voltage.

Preferably, the sequence for selecting the light-emitting diodes as a function of the supply voltage is a random or pseudo-random sequence.

According to one embodiment, the optoelectronic circuit comprises at least one set of several modules mounted in series, the diode selection sequence The overall electroluminescent of the modules of this set is controlled by only one of the modules of this set, called the master module, the other modules of this set being called slave modules. According to one embodiment, each module is capable of being a master module or a slave module and the configuration of each module as a master module or as a slave module is obtained automatically, for example by the way in which the module is connected to the other modules in the optoelectronic circuit.

According to one embodiment, each module comprises a current source for supplying the light-emitting diode of the module. Preferably, only the current source of the master module is activated.

According to one embodiment, the control circuit is adapted to modify the intensity of the current supplied by the current source, for example from a setpoint received by the module.

According to one embodiment, the optoelectronic circuit comprises several modules emitting lights of different colors, one of these modules being suitable for controlling the other modules for controlling the overall color emitted by all the modules.

• des bornes A, K, CS, Vdd, S et Gnd ;
• une diode électroluminescente globale D dont la cathode est reliée à la borne K et dont l'anode est reliée à la borne A ;
• une source de courant 42 dont une borne est reliée à la cathode de la diode électroluminescente globale D et dont l'autre borne est reliée à la borne CS ;
• un circuit de contrôle 44 adapté à fournir un signal S1 de sélection de diodes électroluminescentes globales ;
• un circuit 46 de commande de la diode électroluminescente globale D recevant un signal S2 et adapté à court-circuiter ou à laisser passante la diode électroluminescente globale D en fonction du signal S2 ;
• un circuit de communication 48 adapté à fournir le signal S2 à partir du signal S1 ; et
• un circuit 50 (Bandgap & supplies) de fourniture de tensions/courants d'alimentation aux différents circuits du module 40.

The figure 4 shows an embodiment of a module 40 that can be used for the production of an optoelectronic circuit. Module 40 includes:

• terminals A, K, CS, Vdd, S and Gnd;
• a global light-emitting diode D whose cathode is connected to terminal K and whose anode is connected to terminal A;
• a current source 42, one terminal of which is connected to the cathode of the overall light-emitting diode D and the other terminal of which is connected to the CS terminal;
• a control circuit 44 adapted to supply a signal S1 for selecting global light-emitting diodes;
• a circuit 46 for controlling the overall light-emitting diode D receiving a signal S2 and adapted to short-circuit or to leave on the global light-emitting diode D as a function of the signal S2;
• a communication circuit 48 adapted to supply the signal S2 from the signal S1; and
• a circuit 50 (Bandgap & supplies) for supplying supply voltages / currents to the various circuits of the module 40.

The circuits of the module 40 can correspond in whole or in part to dedicated circuits. However, at least some of these circuits may include a processor adapted to execute a computer program stored in a memory.

Terminal Vdd is intended to be connected to a source of high potential and terminal Gnd is intended to be connected to a source of low potential. Each module 40 has a local ground insofar as the potentials in a module 40 are referenced with respect to the potential at the terminal Gnd of this module 40. The electrical connections between the circuit 50 and the other circuits of the module 40 are not not shown. Likewise, the connections between the circuits of the module 40 and the terminals Vdd and Gnd are not shown. According to another embodiment, each module 40 comprises at least one capacitor which is charged each time the global light-emitting diode D is on and the circuit 50 (Bandgap & supplies) supplies the supply voltages / currents of the various circuits of the module. 40 from the energy stored in the capacitor. The Vdd terminal may then not be present.

The overall light-emitting diode D comprises at least one elementary light-emitting diode and is preferably made up of the placing in series and / or in parallel of at least two elementary light-emitting diodes.

Each module 40 may correspond to a single integrated circuit chip or comprise two integrated circuit chips or more than two integrated circuit chips. Each module 40 corresponds to a separate elementary electronic circuit and all the components of the module 40 are contained in the same housing. In in particular, the overall light-emitting diode D and the integrated circuit chip or the integrated circuit chips comprising the circuits 44, 46, 48 and 50 are contained in the same package.

The control circuit 44 comprises a circuit 51 (System Control Unit) for controlling the module 40, referred to below as a selection circuit. The selection circuit 51 is adapted to select the “master” or “slave” state of the module 40 and to supply a signal S3 to the control circuit 46 representative of the fact that the module 40 operates as a master module or as a slave module. . As a variant, there is no transmission of signal S3 between the control circuit 44 and the control circuit 46. According to one embodiment, the selection circuit 51 is adapted to determine whether the current source 42 of module 40 is in operation. When the current source 42 is in operation, the selection circuit 51 provides for example a signal S3 at "1", which means that the module 40 operates as a master module. When the current source 42 is not in operation, the selection circuit 51 provides for example a signal S3 at "0", which means that the module 40 operates as a slave module. According to one embodiment, the optoelectronic circuit 10 comprises a voltage sensor 52 (Vsense) connected to the selection circuit 51 and adapted to measure the potential at the terminal CS.

According to one embodiment, the selection circuit 51 is suitable for controlling the intensity I _CS of the current supplied by the current source 42. By way of example, the selection circuit 51 is suitable for providing a current setpoint. current I _CS to a current control circuit 53 (Current Control) which converts the setpoint into a control signal for the current source 52.

Each module 40 can furthermore comprise the terminal S which is connected to the selection circuit 51. A circuit external to the modules 40, for example a sensor, not shown in figure 4 , can be connected to terminal S. For example, the setpoint of current I _CS supplied by circuit 51 may depend on the signal received by circuit 51 by terminal S.

According to one embodiment, the selection circuit 51 receives a measurement signal S4 supplied by a sensor 54 (Vsense). By way of example, the sensor 54 is a voltage sensor adapted to measure the voltage at the cathode of the overall light-emitting diode D. The selection circuit 51 is adapted to supply the signal S1 which is representative of the light-emitting diodes of the optoelectronic circuit. to activate / deactivate.

The communication circuit 48 comprises a modulation circuit 58 (Modulation Unit) receiving the signal S1 supplied by the control circuit 44 and a demodulation circuit 60 (Demodulation Unit) supplying the signal S2 to the control circuit 46. The modulation circuits 58 and demodulation 60 implement modulation / demodulation steps so that the signal S2 is, like the signal S1, representative of the light-emitting diodes of the optoelectronic circuit to be activated / inhibited.

The control circuit 46 comprises a control circuit 62 (Switch Control) receiving the signal S2 and the signal S3 and supplying a control signal S5 to a switch 64 mounted at the terminals of the overall light-emitting diode D. By way of example, the signal S5 is a binary signal and the switch 64 is open when the signal S5 is in a first state, for example the low state, and the switch 64 is closed when the signal S5 is in a second state, for example high state. Each switch 64 is, for example, a switch based on at least one transistor, in particular a field effect transistor with a metal-oxide gate or MOS transistor, with enrichment (normally closed) or depletion (normally open). According to one embodiment, each switch 64 corresponds to a MOS transistor, for example N-channel transistor, the drain of which is connected to the anode of the overall light-emitting diode D, the source of which is connected to the cathode of the global light-emitting diode D and the gate of which receives the signal S5.

In the present embodiment, the modulation / demodulation step implemented by the communication circuit 48 comprises the modulation of the current I _CS supplied by the current source 42. The modulation circuit 58 is then adapted to control the source. current 42 to modulate the current I _CS supplied by the current source 42. The communication circuit 48 further comprises a circuit 66 for detecting the modulation of the current I _CS comprising a diode 68 connected in series between the terminal A and the anode of the global light-emitting diode D and a sensor 70 of the voltage across the terminals of the diode 68, supplying a signal S6 to the demodulation circuit 60.

The figure 5 represents an embodiment of an optoelectronic circuit 80 comprising N modules 40 such as represented in figure 4 , where N is an integer between 2 and 200, three modules 40 being represented by way of example in figure 5 . The modules 40 correspond to distinct elementary circuits. In particular, the housings of the modules 40 are distinct. According to one embodiment, the optoelectronic circuit 80 comprises a succession of modules 40 mounted in series between a node A ₁ and a node A ₂ , the module at the first position of the succession being that connected to node A ₁ and the module at the last position of the succession being that connected to node A ₂ . A supply voltage V _ALIM is applied between the nodes A ₁ and A ₂ . The supply voltage V _ALIM can correspond to the oscillating voltage supplied by a rectifier circuit. As a variant, the supply voltage can be a direct voltage, for example a substantially constant voltage.

For each module 40, terminal Vdd is connected to node A ₁ by a resistor 82 which may be identical or different depending on the modules 40. The value of each resistor 82 is chosen so that, for each module 40, the potential at the terminal Vdd is within a range of values suitable for correct operation of the circuit 50 for supplying the supply voltages / currents of the components of the module 40.

• la borne K est laissée flottante ;
• lorsque le module maître est connecté au noeud A₁, la borne A du module maître est connectée au noeud A₁ ;
• lorsque le module maître est connecté au noeud A₂, les bornes CS et Gnd du module maître sont connectées au noeud A₂ ;
• lorsque le module maître n'est pas à une extrémité de la succession de modules 40, la borne A du module maître est connectée aux bornes K et Gnd du module esclave précédent et les bornes CS et Gnd du module maître sont connectées à la borne A du module esclave suivant.

For the master module, the connections of terminals A, K, Gnd and CS are made as follows:

• terminal K is left floating;
• when the master module is connected to node A ₁ , terminal A of the master module is connected to node A ₁ ;
• when the master module is connected to node A ₂ , the terminals CS and Gnd of the master module are connected to node A ₂ ;
• when the master module is not at one end of the succession of modules 40, terminal A of the master module is connected to terminals K and Gnd of the previous slave module and terminals CS and Gnd of the master module are connected to terminal A of the next slave module.

• la borne CS est laissée flottante ;
• lorsque le module esclave est connecté au noeud A₁, la borne A du module esclave est connectée au noeud A₁ ;
• lorsque le module esclave est connecté au noeud A₂, les bornes K et Gnd du module esclave sont connectées au noeud A₂ ;
• lorsque le module esclave n'est pas à une extrémité de la chaîne, la borne A du module esclave est connectée aux bornes K et Gnd du module précédent lorsque le module précédent est un module esclave ou aux bornes CS et Gnd du module précédent lorsque le module précédent est le module maître et les bornes K et Gnd du module esclave sont connectées à la borne A du module suivant (esclave ou maître).

For each slave module, the connections of terminals A, K, Gnd and CS are made as follows:

• the CS terminal is left floating;
• when the slave module is connected to node A ₁ , terminal A of the slave module is connected to node A ₁ ;
• when the slave module is connected to node A ₂ , the terminals K and Gnd of the slave module are connected to node A ₂ ;
• when the slave module is not at one end of the chain, terminal A of the slave module is connected to terminals K and Gnd of the previous module when the previous module is a slave module or to terminals CS and Gnd of the previous module when the previous module is the master module and the K and Gnd terminals of the slave module are connected to the A terminal of the next module (slave or master).

Preferably, the modules 40 are connected to each other so that there is only one master module, shown by way of example in the last position in figure 5 .

The operation of the optoelectronic circuit 80 is as follows. The selection circuit 51 of each module 40 determines whether the CS terminal is left floating. If this is the case, the selection circuit 51 transmits an inhibition signal S3 to the control circuit. command 46 and the module considered operates as a slave module. When the CS terminal is detected as not being left floating, the selection circuit 51 transmits an activation signal S3 to the control circuit 46 and the module considered operates as a master module. The detection of whether the CS terminal is floating or not can be performed by comparing the potential at the CS terminal and the potential at the Gnd terminal. If the potentials are equal, this means that the CS terminal is not floating and if the potentials are different, this means that the CS terminal is left floating.

In operation, the control circuit 44 of the master module controls the modulation circuit 58 to transmit data by modulating the current I _CS . The modulation of the current I _CS can be a modulation of any type, for example an amplitude modulation and / or a frequency modulation. The modulation circuit 58 of each slave module remains inactive. The demodulation circuit 60 of each module is suitable for receiving the data transmitted by demodulation of the current I _CS and the driving circuit 62 is suitable for controlling the opening or closing of the switch 64 as a function of the data received.

According to one embodiment, the data supplied by the master module and transmitted to each slave module by modulation of the current I _CS can be representative of an order of activation of the overall light-emitting diodes during the evolution of the voltage of supply V _ALIM , for example during each cycle of voltage V _ALIM in the case of a voltage V _ALIM varying periodically. This activation order can be modified over time so that the order of activation of the overall light-emitting diodes is not always the same for each cycle of the supply voltage V _ALIM . By way of example, the order of activation of the global light-emitting diodes can be random.

According to one embodiment, each module is associated with a unique identifier and the data supplied by the master module include in particular a succession of identifiers. The list of identifiers can be stored in a memory of the control circuit 46. By way of example, when a slave module receives the identifier associated with it, it changes the state of the switch 64, to open to closed or closed to open.

The figures 6 and 7 are figures analogous to figures 4 and 5 respectively of another embodiment of a module 90 and of an optoelectronic circuit 95 comprising several examples of the module 90.

The elements common between the module 40 and the module 90 are designated by the same references. The module 90 comprises all the elements of the module 40 with the difference that there is no modulation of the current I _CS by the modulation circuit 58 and that the modulation circuit 58 is adapted to supply a modulated current I _mod to an I_ctrl terminal. The module 90 further comprises two terminals I_ctrl_in and I_ctrl_out and the communication circuit 48 comprises a copy circuit 96 connected to the terminals I_ctrl_in and I_ctrl_out and linked to the demodulation circuit 60 and adapted to supply a copy of the current flowing between the terminals I_ctrl_in and I_ctrl_out to demodulation circuit 60.

In the present embodiment, the transmission of data between the master module and the slave modules is carried out by a modulation of the current I _mod which is transmitted on a conductive line dedicated by the master module to the slave modules.

In the optoelectronic circuit 95, the connection of the terminals A, K, Vdd and Gnd of each module 90 is identical to what has been described previously for the module 40 in relation to the figure 5 with the difference that the master module is preferably placed in the last position, that is to say connected to node A ₂ . In addition, the I_ctrl terminal of the master module is connected to the I_ctrl_in terminal of the master module and the I_ctrl_out of the master module is connected to the I_ctrl_in terminal of the preceding slave module in the succession of modules. For each slave module, the I_ctrl terminal is not used. She is left floating or fixed at a neutral potential adequate for the operation of the circuit. The I_ctrl_in terminal is connected to the I_ctrl_out terminal of the next module in the succession of modules and the I_ctrl_out terminal is connected to the I_ctrl_in terminal of the previous module in the succession of modules, with the exception of the slave module in the first position whose terminal I_ctrl_out is connected to node A ₁ or Vdd via a resistor.

The operation of the optoelectronic circuit 95 is as follows. The role of master module or slave module is determined as described above for optoelectronic circuit 80. In operation, modulation circuit 58 of the master module, under the control of selection circuit 51, modulates current I _mod to transmit data by modulating the current I _mod . The modulation of the current I _mod can be of any type, for example an amplitude modulation and / or a frequency modulation. The modulation circuit 58 of each slave module remains inactive. The current I _mod flows from module to module by passing through the feedback circuit 96 of each module 90. The feedback circuit 96 of each module 90 supplies a copy of the current I _mod to the demodulation circuit 60. The demodulation circuit 60 of each module is suitable for receiving the data transmitted by demodulation of the current I _mod and the control circuit 62 is suitable for controlling the opening or closing of the switch 64 as a function of the data received.

An advantage of the present embodiment is that the modulation of the current I _mod by the modulation circuit 58 of the master module can be implemented more simply than the modulation of the current I _CS in the embodiment described above in relation to the figures 4 and 5 . Indeed, the impedance seen by the current source 42, due to the overall light-emitting diodes of all the modules is higher than the impedance seen by the modulation circuit 58 due to the feedback circuits 96. In addition, the modulation does not affect the light emitted.

The figures 8 and 9 are figures analogous to figures 4 and 5 respectively of another embodiment of a module 100 and of an optoelectronic circuit 105 comprising several examples of the module 100.

The elements common between the module 100 and the module 90 are designated by the same references. The module 100 comprises all the elements of the module 90 with the difference that the terminal I_ctrl_out is not present and that the terminal I_ctrl_in is connected directly to the demodulation circuit 60.

In the present embodiment, the data transmission between the master module and the slave modules is carried out by high frequency modulation of the potential at the I_ctrl terminal.

The connection of the terminals A, K, Vdd and Gnd of each module 100 is identical to what was described previously for the module 40 in relation to the figure 5 . In addition, for each slave module, the I_ctrl terminal is left floating. For each module, the I_ctrl_in terminal is connected to a conductive line 106 by a capacitor 108. In addition, the I_ctrl terminal of the master module is connected to the conductive line 106 by a capacitor 109.

The operation of the optoelectronic circuit 105 is as follows. The role of master module or slave module is determined as described above for optoelectronic circuit 80. In operation, modulation circuit 58 of the master module, under the control of selection circuit 51, varies the potential. to the I_ctrl terminal to transmit data to the slave modules. The variations of the potential at the I_ctrl terminal are reproduced at the I_ctrl_in terminals of each slave module by capacitive coupling. The potential modulation at the I_ctrl terminal can be of any type, for example amplitude modulation and / or frequency modulation. The modulation circuit 58 of each slave module remains inactive.

The demodulation circuit 60 of each module is adapted to receive the data transmitted to the terminal I_ctrl_in and the control circuit 62 is suitable for controlling the opening or closing of the switch 64 as a function of the data received.

According to one embodiment, each control circuit 46 is, moreover, adapted to modulate the potential at the terminal I_ctrl_in. Bidirectional communication can then be implemented between the master module and the slave modules. The supply of the signal S3 from the control circuit 44 to the control circuit 46 makes it possible to facilitate the setting up of a bidirectional communication protocol between the master module and the slave modules, in particular concerning the priorities of access to the communication channel. An advantage of the present embodiment is that the data transmission between the modules is carried out by capacitive coupling and therefore allows the implementation of a bidirectional communication between the master module and each slave module, the performance of which does not depend on the position. relative in the succession of modules between the master module and the slave module.

Advantageously, it is not necessary to store beforehand in a memory of the master module the number of modules making up the optoelectronic circuit 105. In fact, each slave module can signal itself to the master module, for example when the optoelectronic circuit is started. 105, the activation sequence of the light-emitting diodes then being adapted by the master module as a function of the number of slave modules. This makes it possible to modify in a simple manner the number of modules of the optoelectronic circuit 105.

In the present embodiment, the exchange of data between the master module and each slave module is carried out by a single wire link. According to another embodiment, the transmission of data from the master module to each slave module is carried out using a two-wire link, corresponding, for example, to an I ² C or other bus.

The figures 10 and 11 are figures analogous to figures 8 and 9 respectively of another embodiment of a module 110 and an optoelectronic circuit 115 comprising several examples of module 110.

The elements common between the module 110 and the module 100 are designated by the same references. The module 110 comprises all the elements of the module 100 with the difference that the module 110 comprises an additional terminal MS and that the selection circuit 51 of the module 110 is connected to the terminal MS instead of being connected to the terminal CS as is the case for module 100.

In the present embodiment, the transmission of data between the master module and the slave modules can be carried out as has been described previously for the module 100. As a variant, the transmission of data between the master module and the slave modules can be implemented as has been described for module 40 or module 90.

The connection of terminals A, K, CS, K, Vdd and Gnd of each module 110 is identical to what has been described previously for module 40 in relation to figure 5 . In addition, for each slave module, the MS terminal is left floating. For the master module, the MS terminal is connected to the CS terminal.

The selection circuit 51 of each module 40 determines whether the terminal MS is left floating or at a neutral potential other than GND. If this is the case, the selection circuit 51 transmits an inhibition signal S3 to the control circuit 46 and the module considered operates as a slave module. When the terminal MS is detected as not being left floating, the selection circuit 51 transmits an activation signal S3 to the control circuit 46 and the module considered operates as a master module.

The figure 12 is a figure similar to the figure 4 of another embodiment of a module 120 comprising light emitting diodes.

The module 120 has the same structure as the module 40 with the difference that certain elements are present in triplicate. On the figure 12 , we added the index "1", "2" and "3" to a reference designating an element of the module 40 to designate each copy of this element in the module 120. It is not shown in figure 12 the current control circuits connecting the circuit 51 to each current source 42 ₁ , 42 ₂ and 42 ₃ .

In the present embodiment, the module 120 comprises three overall light-emitting diodes D ₁ , D ₂ and D ₃ . The light-emitting diodes D ₁ , D ₂ and D ₃ can be adapted to emit light radiation at different wavelengths, for example in red, green and blue respectively. The control circuit 62 is suitable for separately controlling each switch 64 ₁ , 64 ₂ and 64 ₃ . The selection circuit 51 receives the signals supplied by the sensors 52 ₁ , 52 ₂ and 52 ₃ and the signals supplied by the sensors 54 ₁ , 54 ₂ and 54 ₃ .

In figure 12 , the elements involved in the transmission of data from the master module to the slave modules are not shown. These elements can correspond to those of any one of the embodiments described above for the modules 10, 40 or 90.

According to one embodiment, the rules for connecting the modules 120 to each other are the same as those described above for the terminals A, CS and K, considering separately the set of terminals A ₁ , CS ₁ and K ₁ , l 'set of terminals A ₂ , K ₂ and CS ₂ and the set of terminals A ₃ , CS ₃ and K ₃ , each set being referenced to the associated terminal Gnd. The overall light-emitting diodes D ₁ of the modules 120 are then connected in series, the overall light-emitting diodes D ₂ are connected in series and the overall light-emitting diodes D ₃ are connected in series. The structure of the module 120 advantageously makes it possible to connect the modules 120 so that a first module plays the role of master module for the light-emitting diodes D ₁ , that a second module, possibly different from the first module, plays the role of master module. role of master module for the light-emitting diodes D ₂ , and that a third module, possibly different from the first module and the second module, plays the role of master module for the light-emitting diodes D ₃ . As a variant, only the sensor 52 ₁ is present. In this case, the three sets of terminals A ₁ , CS ₁ and K ₁ , A ₂ , K ₂ and CS ₂ and A ₃ , CS ₃ and K ₃ are connected in the same way so that the same module plays the role master module for light emitting diodes D ₁ , D ₂ and D ₃ .

In the present embodiment, the structure of the module 120 is derived from that of the module 40, certain elements being present in triplicate. As an alternative, the structure of the module 120 can be derived from the module 110 shown in figure 10 .

The figure 13 shows an embodiment of an optoelectronic circuit 125 comprising a succession of modules 130 mounted in series. In the present embodiment, a circuit 132, external to the modules, is connected to terminal S of the master module. According to one embodiment, the circuit 132 can comprise a sensor, for example a brightness sensor, or can include a variator, and the current setpoint I _CS supplied by the circuit 51 can depend on a signal supplied to the terminal S by the sensor 132. According to another embodiment, the circuit 132 can be integrated into each module 130. According to another embodiment, the circuit 132 can comprise an interface that can be actuated by a user and the activation sequence provided by the user. control circuit 44 of the master module can then depend on the signal supplied by circuit 132. According to one embodiment, in the case where bidirectional communication is carried out between the master module and the slave modules, circuit 132 can be connected to the one of the slave modules and the signals supplied by the circuit 132 to the slave module are retransmitted by this slave module to the master module. As a variant, each module 130 can have a structure similar to that of one of the modules 90, 100 or 110.

The figure 14 represents an embodiment of an optoelectronic circuit 135 comprising a succession of modules 140 mounted in parallel. Each 140 module can include all the elements of module 100 described previously in relation to the figure 8 .

The terminals Vdd and A of each module 140 are connected to a source of a high reference potential VCC. The Gnd and CS terminals are connected to a low reference potential.

Each module 140 is mounted as a master module. Each module 140 is then adapted to control its own light-emitting diode D. The exchange of data between modules 140 can be carried out as has been described previously for the optoelectronic circuit 105 shown in figure 9 . As each module is a master module, for each module, the I_ctrl_in terminal is connected to the conductive line 106 by the capacitor 108 and the I_ctrl terminal is connected to the conductive line 106 by the capacitor 109.

As has been described previously, the exchange of data between the modules can, by way of a variant, be carried out by a two-wire link, corresponding, for example, to an I ² C bus or the like.

According to one embodiment, the light-emitting diodes D of the modules 140 are adapted to emit light at different wavelengths. By way of example, the optoelectronic circuit 135 comprises three modules 140. The light-emitting diodes D of these modules 140 can be adapted to emit light radiation at different wavelengths, for example respectively in red, green and green. blue. The set of modules 140 can then correspond to a display pixel.

Each module 140 is, for example, suitable for modifying the light intensity emitted by the light-emitting diode D that it contains as a function of data supplied by at least one of the other modules 140. The modification of the light intensity can be carried out by any type of modulation, for example by an all-or-nothing modulation of the activation / inhibition switch of the light-emitting diode D or by a modulation of the intensity of the current supplied by the current source 42. According to one embodiment, one of the modules 140 is adapted to receive a setpoint of a property of the radiation emitted by the optoelectronic circuit 135, for example a color setpoint. The module 140 receiving the instruction transmits data to the other modules 140 so that the property of the radiation emitted by all the light-emitting diodes follows this instruction. This advantageously makes it possible to transmit a general instruction to the electronic circuit while the regulation of the radiation emitted by each module 140 is carried out directly by the module 140 considered.

Advantageously, in the embodiments described above, in particular when the number of elementary light-emitting diodes making up the overall light-emitting diode D is small, preferably less than 10, or even equal to 1, the electronic components used to produce the module 40, 90, 100, 120, 140 can be components suitable for low voltage applications. This makes it possible in particular to reduce the cost of manufacturing the module.

Particular embodiments have been described. Various variations and modifications will be apparent to those skilled in the art. In particular, in the embodiments described above, the signal S4 from which the selection circuit 51 of the master module supplies the activation / inhibition sequence of the overall light-emitting diodes of the modules corresponds to the potential at the cathode of the overall light-emitting diode D. However, the circuit 51 can be controlled by another signal, for example the potential at the anode of the light emitting diode D.

Claims (16)

1. An optoelectronic circuit (80; 95; 105; 115; 125; 135) comprising interconnected separate elementary electronic circuits (40; 90; 100; 110; 120; 140), each elementary electronic circuit comprising:

   at least one light-emitting diode (D); and

   at least one integrated circuit chip comprising a circuit (46) for controlling the light-emitting diode capable of activating or of deactivating the light-emitting diode,

   wherein the optoelectronic circuit is intended to receive a variable supply voltage (V_ALIM),

   wherein each elementary electronic circuit (40; 90; 100; 110; 120; 140) comprises a control circuit (44) capable of supplying an activation or deactivation signal to each of the other elementary electronic circuits according to a selection sequence with respect to the value of the variable supply voltage (V_ALIM), and wherein, for each elementary electronic circuit, the circuit (46) for controlling the light-emitting diode (D) is capable of activating or inhibiting the light-emitting diode according to the activation or deactivation signal, whereby the number of activated light-emitting diodes depends on the value of the variable supply voltage (V_ALIM).
2. The optoelectronic circuit of claim 1, wherein each elementary electronic circuit (40; 90; 100; 110; 120; 140) comprises in a same package said at least one light-emitting diode (D) and said at least one integrated circuit chip.
3. The optoelectronic circuit of claim 1 or 2, wherein the integrated circuit chip of each elementary electronic circuit further comprises a communication circuit (48) containing a modulation circuit (58) capable of supplying a first modulated signal (I_CS; I_mod) from the activation or deactivation signal and a demodulation circuit (60) capable of supplying a second signal (S2) by demodulation of the first signal, the circuit (46) for controlling the light-emitting diode being capable of activating or of inhibiting the light-emitting diode from the second signal.
4. The optoelectronic circuit of any of claims 1 to 3, wherein each elementary electronic circuit comprises a current source (42) coupled to the light-emitting diode (D).
5. The optoelectronic circuit of any of claims 1 to 4, wherein the integrated circuit chip of each elementary electronic circuit further comprises a circuit (51) for detecting a master or slave state of the elementary electronic circuit when the elementary electronic circuit is in operation by the way said elementary electronic circuit is connected to the other elementary electronic circuits.
6. The optoelectronic circuit of claim 5, wherein the elementary electronic circuit in the master state is capable of transmitting data to the other elementary electronic circuits so that the light-emitting diodes are activated randomly or according to a given succession.
7. The optoelectronic circuit of any of claims 1 to 6, comprising a plurality of series-assembled elementary electronic circuits.
8. The optoelectronic circuit of any of claims 1 to 6, comprising a plurality of elementary electronic circuits assembled in parallel.
9. The optoelectronic circuit of claim 6 and of claim 4, wherein each elementary electronic circuit further comprises a first terminal (S), wherein the optoelectronic circuit comprises a sensor (132) coupled to the first terminal of one of the elementary electronic circuits, and wherein the intensity of the current supplied by the current source (42) of the master circuit depends on a third signal supplied by the sensor.
10. The optoelectronic circuit of claim 3, wherein, for each elementary electronic circuit, the first modulated signal corresponds to a modulation of the power supply current of the light-emitting diode (D).
11. The optoelectronic circuit of claim 3, wherein each elementary electronic circuit further comprises a second terminal (I_ctrl), and wherein the first modulated signal (I_mod) corresponds to a modulated current supplied by the modulation circuit (58) to the second terminal (I_ctrl), which is different from the light-emitting diode power supply current or wherein the first modulated signal corresponds to the potential at said terminal.
12. The optoelectronic circuit of claim 11, further comprising a third terminal (I_ctrl_in), the demodulation circuit (60) being capable of receiving the second signal (I_mod) via the third terminal.
13. The optoelectronic circuit of claim 12, wherein the third terminal (I ctrl in) of each elementary electronic circuit is coupled to a conductive line (106; 132) via a capacitor (108; 134).
14. The optoelectronic circuit of claim 12, wherein each elementary electronic circuit further comprises a fourth terminal (I_ctrl_out) and a copying circuit coupling the third terminal and the fourth terminal and capable of supplying the demodulation circuit (60) with a copy of the current flowing between the third and fourth terminals.
15. The optoelectronic circuit of claim 14, wherein the elementary electronic circuits are series-assembled according to a succession of elementary electronic circuits and wherein, for each elementary electronic circuit, except for the elementary electronic circuits located at the ends of the succession, the fourth terminal (I_ctrl_out) of the elementary electronic circuit is coupled to the third terminal (I_ctrl_in) of the previous elementary electronic circuit in the succession.
16. The optoelectronic circuit of any of claims 1 to 15, wherein each elementary electronic circuit comprises less than five light-emitting diodes (D).

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