MOTOR VEHICLE LIGHTING DEVICE WITH MULTIPLE LIGHT SOURCES

Abstract

MOTOR VEHICLE LIGHTING SYSTEM WITH MULTIPLE LIGHT SOURCES The invention proposes a lighting system comprising a plurality of light modules performing mutually exclusive lighting functions for a motor vehicle using a plurality of LED light sources connected in series. The measures of the invention make it possible to reduce the number of converter circuits required to control the power supply of the light modules. Figure to be published with the abstract: Figure 1

Description

Title of the invention: LIGHTING DEVICE OF A MOTOR VEHICLE HAVING MULTIPLE LIGHT SOURCES technical field

[0001] The present invention relates to a motor vehicle lighting device involving a plurality of light sources which can be controlled independently of each other, and a control method for such a lighting device. TECHNOLOGICAL BACKGROUND

[0002] The field of lighting and / or light signaling for motor vehicles is subject to regulations requiring that each motor vehicle be equipped with lights fulfilling specific safety functions, including signal lights, dipped headlights, and main beam headlights. Signal lights are generally used to communicate information to other road users, without providing any additional road illumination function useful to the driver, such as turn signals or daytime running lights (also known as DRLs).

[0003] In order to compact the means of lighting of a motor vehicle, it is sought to group within the same projector the different means enabling the implementation of these signaling functions and these lighting functions, and it may in particular be aimed by the car manufacturers or by the equipment suppliers to have a common optical element for each of these functions, for example in the form of a transparent or translucent screen closing the housing of the projector and from which the light rays emerge forming one or the other of the lighting or signaling beams.

[0004] In order to personalize the optical and lighting signature of a motor vehicle, it may also be advantageous to use matrices of light sources, in which each light source can be individually controlled. This makes it possible, in particular, to program pictograms or images to be represented by such a matrix, with each light source creating one pixel of the image.

[0005] Light sources with a semiconductor light-emitting element, such as a light-emitting diode (LED), are used in such devices due to their compact size. If the voltage across an LED light source exceeds a threshold value called forward voltage, the light source emits light of a predetermined wavelength or color. When a potentially large plurality of such light sources is arranged in a matrix using a series connection along a branch, the fact that each light source is individually controllable and therefore short-circuitable means that the voltage drop across the branch varies according to the activation state of each individual light source. Linear voltage control is impossible in such cases. When several lighting functions or several matrices of light sources are involved in the same lighting device, known solutions require the use of a converter circuit per matrix / series connection of light sources, which results in significant cost, substantial heat generation, and a large footprint in the limited space available for a vehicle lighting system.

[0006] There is therefore a need to be able to have a motor vehicle lighting system comprising a plurality of light sources better adapted to existing constraints, and an adapted control method. SUMMARY

[0007] According to a first aspect of the invention, a motor vehicle lighting device is proposed. The lighting device is notable in that it comprises at least two lighting modules. Each lighting module comprises a series arrangement of a plurality of switch circuits specific to the lighting module, and a plurality of light sources comprising at least one electroluminescent semiconductor element specific to said lighting module. Each series arrangement of switch circuits comprises a first switch circuit and a plurality of second switch circuits. Each light source is associated with one of the second switch circuits, said second switch circuit being specific to the light source, said light source being connected in parallel with said second switch circuit. The lighting device also comprises a voltage converter electrically connected to an input of each lighting module.Each light module further comprises a control unit configured to emit control signals intended to control the open state of the respective switch circuits, based on data received by means of data receiving means, and wherein the control of a first switch circuit of the series arrangement of a light module allows the series arrangement to be selectively powered by means of the converter.

[0008] Preferably, the light sources of a light module can be arranged in a matrix configuration. Preferably, the switching circuits of a light module can be grouped on a control unit involving a circuit dedicated printed circuit board to which the light sources are connected or to which the light sources are electrically connected.

[0009] Preferably, the voltage converter may include a voltage boost converter followed by a voltage step-down converter.

[0010] The switching circuits may preferably include metal-oxide-semiconductor field-effect transistors, MOSFETs.

[0011] Preferably, the data receiving means may include a CAN (Controller Area Network) type interface capable of receiving CAN frames on a data bus of the motor vehicle. Alternatively, the data receiving means may include an Ethernet, UART, or LIN type interface.

[0012] The lighting device may preferably comprise two lighting modules, each grouping light sources with an electroluminescent semiconductor element capable of emitting light of a given color. Preferably, the two colors may comprise white and amber, respectively.

[0013] A first light module may preferably be intended to perform a direction indicator function and a second light module may preferably be intended to perform a daytime running light function.

[0014] According to another aspect of the invention, a motor vehicle is proposed. The motor vehicle is notable in that it comprises at least one lighting device according to one aspect of the invention.

[0015] According to yet another aspect of the invention, a method for controlling a motor vehicle lighting device according to aspects of the invention is proposed. The method is remarkable in that it comprises the steps of providing a command indicating the activation of a specific lighting module by means of receiving data from the lighting modules; at the level of the control unit of said specific lighting module, commanding the first switch circuit to be closed, so as to connect the lighting module in question to the output of the voltage converter; at the level of the units of other lighting modules, commanding the first switch circuit to be opened, so as to disconnect the lighting modules in question from the output of the voltage converter. Thus, the lighting module with the fewest illuminated LEDs is prevented from short-circuiting another branch.

[0016] The method may preferably include the additional step of controlling the respective opening states of the switch circuits mounted in parallel with the light sources of said specific light module, according to a setpoint received by the data receiving means of said light module.

[0017] The proposed invention makes available a motor vehicle lighting device comprising a plurality of light sources better adapted to existing constraints, and an adapted control method.

[0018] The present technology and its various applications will be better understood upon reading the following description and examining the accompanying figures. In particular, the invention eliminates the need for a dedicated boost-buck converter unit for each programmable matrix of LED light sources involved in a single automotive lighting system. Indeed, the proposed architecture allows for the selective and exclusive connection of one of the matrices to a converter stage, thus enabling the sharing of a common converter stage by matrices of light sources intended to perform mutually exclusive lighting functions, such as daytime running lights and a turn signal, for example. A switch circuit for each matrix / light module is preferably used to perform this selective connection.Synchronization between the respective light modules is ensured by means of common instructions received by all the light modules, for example on a data bus of the motor vehicle. BRIEF DESCRIPTION OF THE FIGURES

[0019] The figures are presented for illustrative purposes only and are not exhaustive.

[0020] [Fig. 1] schematically represents a motor vehicle lighting device according to an embodiment of the invention, the lighting device comprising a plurality of lighting modules;

[0021] [Fig.2] schematically represents a motor vehicle lighting device according to an embodiment of the invention, the lighting device comprising a plurality of lighting modules. DETAILED DESCRIPTION

[0022] Figure 1 schematically represents a lighting device 100 for a motor vehicle according to a first embodiment of the invention. The illustrated lighting device comprises two light modules 110, 130, each intended to perform mutually exclusive lighting functions, such as daytime running lights and turn signals, for example. A greater plurality of such light modules may be involved without departing from the scope of the present invention.

[0023] Each module 110, 130 comprises a plurality of switching circuits mounted in series on one branch. Thus, the switching circuits 112, 114, 116, 118 form a series connection of the first light module 110, and the switching circuits 132, 134, 136, 138 form a series connection of the second light module 130. Although [Fig. 1] shows four switching circuits per connection, in practice Each assembly will include hundreds of switch circuits, and the plurality per light module (110, 130) may vary. Each switch circuit is preferably implemented using a MOSFET transistor. The switch circuits of a light module can advantageously be arranged on the same printed circuit board or control module.

[0024] Each module 110, 130 also includes a plurality of light sources with a semiconductor light-emitting element, LEDs, each light source being connected in parallel with one of the switches of the respective light module. Thus, for the first light module 110, the light source 115 is connected in parallel with the switch circuit 114, the light source 117 is connected in parallel with the switch circuit 116, and the light source 119 is connected in parallel with the switch circuit 118. For the second light module 130, the same applies to the connection of the light sources 135, 137, and 139 with respect to the switch circuits 134, 136, and 138. In practice, each module comprises about ten light sources arranged along a branch in the same way, preferably between 10 and 14 light sources per module.The light sources of a branch are also preferentially arranged physically in a matrix. Individually short-circuiting each source of a branch, via its associated switch circuit, allows each light source to represent a pixel of an image or pictogram to be created.

[0025] The device 100 also includes a voltage converter circuit 150, which provides a supply voltage level to the light modules 110, 130 from an electrical voltage Vin supplied by a motor vehicle battery. Converter circuits are well known in the art, and their architecture and operation will not be described in detail within the scope of the present invention.

[0026] Each light module 110, 130 includes a first switch circuit 112, 132 that is not associated with a corresponding light source and is arranged upstream of the switch circuits associated with the light sources. For example, in the illustrated example, the first switch circuit is located upstream of the circuit of the second set of switch circuits, in the direction of the current. When switch 112 is closed while switch 132 is open, only the light sources 115, 117, 119 can be selectively powered, depending on the open state of the switch circuits 114, 116, 118 associated with them. However, the light sources 135, 137, 139 are disconnected from the converter circuit 150 regardless of the state of the switch circuits 134, 136, 138 associated with them. When switch 112 is open while the switch When 132 is closed, only the light sources 135, 137, and 139 can be selectively powered, depending on the open state of the associated switch circuits 134, 136, and 138. However, the light sources 115, 117, and 119 are then disconnected from the converter circuit 150, regardless of the state of their associated switch circuits 114, 116, and 118.

[0027] The respective open or closed states of the switch circuits 112, 114, 116, 118 and 132, 134, 136, 138 of a given light module 110, 130 are controlled by a control unit 120, 140 specific to the module. The control unit 120, 140 preferably includes data receiving means that allow it to receive instructions on a data bus, such as a CAN bus, from the motor vehicle. In the illustration in [Fig. 1], the same instruction is sent to the control units 120, 130 of both modules. For example, if the instruction indicates the lighting of the first module 110, the control unit 120 generates a control signal 122 intended to close the switch circuit 112, thus connecting the light module 110 to the output of the converter circuit 150. Similarly, the control unit 140 generates a control signal 142 intended to open the switch circuit 132, thus isolating the light module 130 from the output of the converter 150.The control units 120, 140 are preferably microcontroller elements programmed for this purpose. The light sources of the powered light module 110 are then individually controlled by means of control signals 124, 126, 128. The control unit can, for example, be configured to reflect, by means of these commands, a binary image received as a setpoint 10. If, on the other hand, the initial setpoint 10 indicates the lighting of the second module 130, the control unit 140 generates a control signal 142 intended to close the switch circuit 132, thus connecting the light module 130 to the output of the converter circuit 150. Similarly, the control unit 120 generates a control signal 122 intended to open the switch circuit 112, thus isolating the light module 110 from the output of the converter 150. The light sources of the powered light module 130 are then individually controlled by means of control signals 144, 146, 148.Thus, the common output of the converter circuit is shared between two light modules. Compared to previously proposed solutions that require one converter circuit per matrix light module, the converter circuit of the proposed solution allows for the control of a plurality of light modules.

[0028] The potential of each transistor involved in one of the switching circuits is floating, since the voltage drop along the branch depends on the open or closed state of the other switching circuits in the same branch.

[0029] Figure 2 schematically represents a lighting device 200 for a motor vehicle according to a second embodiment of the invention. The device The illustrated light is largely similar to the described device 100. It comprises two light modules 210, 230 which are intended to perform mutually exclusive lighting functions, such as daytime running lights and direction indicators, for example.

[0030] Each module 210, 230 comprises a plurality of switch circuits mounted in series on one branch. Thus, the switch circuits 212, 214, 216, 218 form a series connection of the first light module 210, and the switch circuits 232, 234, 236, 238 form a series connection of the second light module 230. Each switch circuit is preferably implemented using a MOSFET transistor. The switch circuits of a light module can advantageously be arranged on the same printed circuit board or control module.

[0031] Each module 210, 230 also includes a plurality of light sources with a semiconductor light-emitting element, LEDs, each of the light sources being mounted in parallel with one of the switches of the respective light module. The mounting of the light sources 215, 217, 219 and the switches 214, 216, 218 of the first light module 210 and the light sources 235, 237, 239 as well as the switches 244, 246, 248 and their control by the respective control units 220, 240 is similar to that just described in the context of the first embodiment.

[0032] The device 100 also includes a voltage converter circuit 150, which provides a supply voltage level to the light modules 110, 130 from an electrical voltage Vin supplied by a vehicle battery. Converter circuits are well known in the art, and their architecture and operation will not be described in detail within the scope of the present invention.

[0033] Unlike the first embodiment, the converter circuit 250 comprises a first voltage-boosting stage, followed by a second voltage-stepping stage 254, of the "buck" type, the output of which is selectively and mutually exclusively connected to the light modules 210, 230. The output of the voltage-boosting stage can, in particular, be shared between stage 254 and other buck stages 254' intended to be connected to other light modules 210', 230' similar to modules 210, 230, without departing from the scope of the present invention. This further improves the use of the converter circuits involved and reduces their number in the lighting device, thereby decreasing their thermal and bulky impact.

[0034] Another difference, which is independent of the difference at the converter level, is illustrated at the setpoint 10. Thus, the control units 220 and 240 are connected serially. The control unit 220 of the first light module 210 receives the setpoint from a control module of the vehicle, and relays it to the control unit 240 of the second light module 240. The interpretation of instructions at the control unit level remains as described for the first embodiment. It goes without saying that this option can be integrated into the first embodiment.

[0035] The extent of the protection sought is determined by the claims.

Claims

Demands

1. A motor vehicle lighting device (100, 200) comprising: - at least two lighting modules (110, 130; 210, 230), each comprising a series arrangement of a plurality of switch circuits specific to said lighting module (112, 114, 116, 118; 132, 134, 136, 138; 212, 214, 216, 218; 222, 224, 236, 238), and a plurality of light sources comprising at least one electroluminescent semiconductor element (115, 117, 119; 135, 137, 139; 215, 217, 219; 235, 237, 239), specific to said lighting module, each series arrangement of switch circuits comprising a first switch circuit and a plurality of second switch circuits, each of the light sources being associated with one of the second circuits switches, said second switch circuit being specific to the light source, said light source being connected in parallel with said second switch circuit;- a voltage converter (150, 250) electrically connected to an input of each light module; in which each light module further comprises a control unit (120, 140; 220, 240) configured to emit control signals intended to control the opening state of the respective switch circuits, according to data received (10) by means of data receiving means, and in which the control (122, 142; 222, 242) of a first switch circuit (112, 132; 212, 232) of the series assembly of a light module allows the series assembly of said module to be selectively powered by means of the converter.

2. Device (200) according to the preceding claim, characterized in that the voltage converter (250) comprises a voltage boost converter (252) followed by a voltage step-down converter (254).

3. Device according to any one of the preceding claims, characterized in that the switching circuits comprise MOSFET-type transistors.

4. Device according to any one of the preceding claims, characterized in that the data receiving means comprise a CAN-type interface.

5. Device according to any one of the preceding claims, characterized in that it comprises two light modules (110, 130; 210, 230), each grouping together light sources with an electroluminescent semiconductor element capable of emitting light of a given colour.

6. Device according to the preceding claim, characterized in that a first light module is intended to perform a direction indicator function and in that a second light module is intended to perform a daytime running light function.

7. - Motor vehicle, characterized in that it comprises at least one lighting device (100, 200) according to any one of the preceding claims.

8. A method for controlling a motor vehicle lighting device (100, 200) according to any one of claims 1 to 6, comprising the steps of: - providing a command (10) indicating the activation of a specific lighting module (110, 130; 210, 230) by the data reception means of the lighting modules; - at the level of the control unit (120, 140; 220, 240) of said specific lighting module, commanding the first switch circuit to be closed, so as to connect the lighting module in question to the output of the voltage converter; - at the level of the units of the other lighting modules, commanding the first switch circuit to be opened, so as to disconnect the lighting module in question from the output of the voltage converter.

9. Method of controlling a motor vehicle lighting device according to the preceding claim, comprising the additional step of controlling the respective opening states of the switch circuits mounted in parallel with the light sources of said specific lighting module, according to a command received by the data receiving means of said lighting module.

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