Method for generating a standard lighting command, lighting system, computer program

Description

[0001] The invention relates to lighting modules for motor vehicles. In particular, the invention relates to such modules involving matrix light sources.

[0002] A light-emitting diode, LED, is a semiconductor electronic component capable of emitting light when passed through it by an electric current having at least a threshold intensity. In the automotive field, LED technology is increasingly used for various light signaling solutions. LED matrices are particularly interesting in the field of automotive lighting. Matrix light sources can be used for "leveling" type functions, i.e., adjustment of the height of the emitted light beam, depending on the vehicle's attitude and the road profile.Other applications include DBL ("Digital Bending Light"), which corresponds to the adjustment of the direction of the emitted light beam, to follow the road in the horizontal plane, ADB ("Adaptive Driving Beam"), which corresponds to an anti-glare function that generates shadow zones in the light beam emitted by a main beam so as not to disturb other road users, but also functions for projecting patterns on the ground using the pixelated light beam.

[0003] It is known to use light sources of different types of technologies for the lighting applications mentioned. This is for example the monolithic technology, according to which a large plurality of elementary sources of the LED type, equivalent to pixels, are etched in a common semiconductor substrate. Integrated electrical connections make it possible to activate the pixels independently of each other. Another known technology is that of microLEDs, which generates a matrix of LEDs of small dimensions, typically less than 150µm. There are also micro-mirror type modules, DMD (Digital Micro-Mirror Device), which involve a projection technology using an intensity modulator on a uniform beam.Micro-mirrors, whose position is controlled by means of piezoelectric elements, are oriented so as to selectively reflect an incident light beam, so that each micro-mirror corresponds to an elementary source of the pixel matrix thus generated. The light from a source is directed onto the micro-mirror matrix by an optic. This light therefore has a variable distribution from one module to another, due to the positioning and manufacturing tolerances of the optics and the light source. This results in a variable maximum intensity from one module to another, for a given pixel. In this case, each pixel will have a different maximum intensity depending on the command transmitted to it. Such lighting devices are designed by mass production methods.There must be clearance between the constituent elements of the lighting and / or signaling device, on the one hand to allow easy assembly, and on the other hand because the parts are generally not machined but rather molded in plastic, which reduces production costs.

[0004] It is particularly important to emphasize the difficulty of perfectly aligning a micro-mirror matrix with the optical projection part, which generally comprises at least one lens. Due to the large numerical aperture of the objective used for the projection function, the projection quality of the image deteriorates significantly as soon as the lateral offset of the optical axis reaches a few micrometers. In practice, distortions of the projected image are therefore inevitable when using solutions known in the art. Each projection module of this type has its own set of optical characteristics, in particular geometric aberration characteristics, including optical distortion and spherical aberration properties. When producing micro-mirrors, geometric aberrations can be introduced. All of these elements result in non-homogeneous behavior of the matrix light source.

[0005] All of these aforementioned modules have specific characteristics related to the combination of manufacturing tolerances of the components. During the production of semiconductor components such as LEDs or LED matrices, variations in direct current are currently unavoidable. It follows that in a given matrix of LEDs, at equal load current, the LEDs emit light beams of variable, non-homogeneous intensities. While it is possible to correct projection instructions in order to take into account the electronic and / or optical specificities of a lighting module, when a defect occurs at the level of the lighting module, it is nevertheless important to be able to project a default image that avoids dazzling other road users.

[0006] Methods for implementing a lighting module equipped with a matrix light source making it possible to take into account variabilities and / or geometric aberrations are known from the French patent application publication FR3072531, as well as from the French patent application publication FR3055980. However, these methods do not allow the generation of a default lighting setpoint taking into account these variabilities.

[0007] The invention aims to overcome at least one of the problems posed by the prior art. More specifically, the invention aims to propose a lighting module and a control method that make it possible to calibrate the luminous and / or geometric behavior of the elementary light sources grouped in a matrix light source of a motor vehicle when a fault is detected. The aim is to provide the means to produce a homogeneous light beam that conforms to a predetermined setpoint, independently of the instance of the matrix light source installed in the lighting module.

[0008] According to a first aspect of the invention, a method for generating a default lighting setpoint for a lighting module for a motor vehicle is proposed. The lighting module comprises a matrix light source grouping a plurality of elementary light sources, a data receiving and sending unit for receiving / sending data from / to a control module of the motor vehicle. The control module comprises first data relating to the motor vehicle. The lighting module further comprises a control unit intended to control said matrix light source, and a memory element comprising second calibration data relating to said matrix light source.The method is remarkable in that the default instruction is intended to serve as a command to the matrix light source in the event of a failure of the communication between the control module 20 of the motor vehicle and the lighting module 100, and in that it comprises the steps of . a) calculating, using a calculation unit, a default lighting setpoint, using at least part of said first data and at least part of said second data; b) recording the default lighting setpoint in a memory element of the lighting module.

[0009] Preferably, the method may comprise the preliminary step of sending at least a portion of the second calibration data by means of the data sending unit to the control module of the motor vehicle. Preferably, the calculation unit may be part of said control module and the method may preferentially further comprise, before step b), the transmission of the default lighting setpoint from the control module to the lighting module.

[0010] The method may preferably comprise the step of recording, at the control module, the second calibration data received in a memory element, in order to reuse them later.

[0011] Preferably, the method may comprise a subsequent step of sending a lighting instruction from the control module to the lighting module, the transmitted lighting instruction taking into account said calibration data.

[0012] Preferably, the method may comprise the preliminary step of receiving at least a portion of the first data relating to the motor vehicle by means of the data receiving unit from the control module of the motor vehicle. The computing unit may preferably be part of said lighting module.

[0013] The method may preferably comprise a subsequent step of receiving a lighting instruction from the control module at the lighting module, and a step of controlling, by means of the control unit of the lighting module, the matrix light source as a function of said lighting instruction and the calibration data stored in the memory element of the module.

[0014] Preferably, the method may comprise a step of correcting the received lighting setpoint, using the calibration data stored in the memory element of the lighting module.

[0015] The method may preferably comprise a subsequent step of detecting, by means of a detection unit, a fault at the level of the control module and / or at the level of the lighting module, and of controlling the matrix source thereafter using said default setpoint.

[0016] The first data relating to the motor vehicle may preferably include data that describes the trim, the position of the lighting module, the position of other lighting modules, or a combination of the above.

[0017] The second calibration data may preferably comprise for each elementary source an indication of the light intensity emitted as a function of an electric charging current, an indication of a geometric aberration of a light beam that the lighting module is capable of emitting, or a combination of the above.

[0018] Preferably, the default lighting instruction may include an image that represents a dipped beam cutoff.

[0019] Preferably, said lighting instruction may comprise an elementary instruction per elementary light source.

[0020] Said lighting instruction may preferably comprise an image. Preferably, at least one pixel of the image may correspond to an elementary light source. The resolution of the image may preferably be greater than the projection resolution of the matrix light source. Preferably, one pixel of the image may correspond to an elementary light source.

[0021] At least part of the data exchanged between the control module of the motor vehicle and the control unit of the lighting module can preferably be encrypted and / or signed using at least one cryptographic key.

[0022] Preferably, a failure in the lighting module and / or the control module of the motor vehicle can be detected when the decryption of the data is not successful or when said signature cannot be validated.

[0023] According to another aspect of the invention, a lighting system for a motor vehicle is provided. The system is remarkable in that it comprises a control module of a motor vehicle, the control module comprising first data relating to the motor vehicle, the control module being connected by a data channel to a lighting module which comprises a control unit and a matrix light source as well as a memory element comprising second calibration data relating to said matrix light source. The system is further remarkable in that the control module and the lighting module are configured to implement the steps of the method according to the preceding aspect of the invention.

[0024] The lighting module may preferably comprise a data receiving / sending unit. The data receiving and sending unit may preferably comprise a network interface capable of receiving / sending data on a data bus internal to the motor vehicle. For example, the bus may be an Ethernet bus, a Gigabit Multimedia Serial Link, GMSL, bus, or a Low Voltage Differential Signaling, LVDS, technology bus, such as an FPD-Link III bus.

[0025] The control unit may preferably comprise a microcontroller element. The control unit may preferably comprise a chip of the “Field Programmable Gate Array”, FPGA, “Application Specific Integrated Circuit”, ASIC, or “Complex Programmable Logic Device”, CPLD type. These elements are configured by means of an appropriate computer program to implement the described functionalities.

[0026] The matrix light source may preferably comprise a monolithic source, comprising elementary electroluminescent light sources with semiconductor elements etched in a common substrate and activatable independently of each other.

[0027] The matrix light source may preferably comprise a micro LED type matrix, comprising a matrix of elementary sources produced by light-emitting diodes, LEDs, of small dimensions, typically less than 150 µm.

[0028] The matrix light source may preferably comprise a micro-mirror device, DMD, (“Digital micromirror device”), in which an elementary source comprises a micro-mirror of a matrix, which selectively reflects an incident light beam depending on its position.

[0029] The control unit may preferably be configured to control said matrix light source by correcting said lighting setpoint using at least part of said calibration data.

[0030] Preferably, the control unit may be configured to transmit at least a portion of said calibration data to a control module of the motor vehicle.

[0031] The lighting module may preferably comprise a second memory element in which data for authenticating the module is stored. Preferably, the lighting module may comprise a processor programmed to encrypt and / or sign data using a cryptographic key stored in said memory element.

[0032] A computer program comprising a sequence of instructions is provided, which, when executed by a processor, cause the processor to implement a method according to one aspect of the invention.

[0033] A non-transitory computer-readable storage medium is provided, said medium storing a computer program according to the preceding paragraph.

[0034] By using the measurements proposed by the present invention, it becomes possible to propose a method which makes it possible to record a default lighting setpoint in a lighting module, which takes into account both calibration data specific to the lighting module, and data relating to the motor vehicle with which it is equipped. This data includes, for example, the attitude of the motor vehicle, or the position of the lighting module relative to other components of the motor vehicle. This information makes it possible to calibrate a default image, representing, for example, a cut-off of dipped headlights, and to physically associate it with the lighting module. Preferably, this method is carried out when the lighting module is installed in the motor vehicle, or during pairing between the control module of the motor vehicle on the one hand, and the lighting module on the other hand.Aspects of the invention further make it possible to produce a homogeneous light beam conforming to a predetermined setpoint, independently of the instance of the matrix light source installed in the lighting module. To achieve this, in accordance with aspects of the invention it is proposed that the calibration parameters are stored on a memory fixed to the lighting module, said parameters comprising for example brightness or electric current correction values for each pixel of a matrix source, or geometry corrections of the beam produced by the lighting module. In this way, it is ensured that the data associated with the module are physically attached to it, in particular at the time of pairing the lighting module with the motor vehicle. This makes it possible to avoid an additional parameterization step which could cause errors during the assembly of a vehicle headlight using the lighting module.Using the measures of the invention, an assembly or a change of module can be carried out without software manipulation: for example, there is no need to transfer or update data relating to the module in a memory of the motor vehicle controller.

[0035] Other features and advantages of the present invention will be better understood with the aid of the description of the examples and the drawings among which: there [ Fig. 1 ] shows the sequence of the main steps of a method in accordance with a preferred embodiment of the invention; the [ Fig. 2 ] is an illustration of a lighting system in accordance with a preferred embodiment of the invention.

[0036] Unless specifically indicated otherwise, technical features described in detail for a given embodiment may be combined with technical features described in the context of other embodiments described by way of example and in a non-limiting manner.

[0037] The description focuses on the elements of a lighting module for a motor vehicle that are necessary for understanding the invention. Other elements, which are known to be part of such modules, will not be mentioned or described in detail. For example, the presence and operation of a converter circuit involved in the power supply of a matrix light source, known per se, will not be described in detail. The same applies to optical elements such as lenses, for example.

[0038] The illustration of the figure 1 shows the sequence of the main steps of the method according to a preferred embodiment of the first aspect of the invention, as represented by the first claim. The figure 2 shows in a non-limiting manner a lighting system for a motor vehicle which allows this method to be carried out. The method relates to the generation of a default image and it is preferably part of a pairing sequence between the motor vehicle and a lighting module. The system notably comprises a lighting module 100. The module comprises a matrix light source 110 grouping together a plurality of elementary light sources 112. In the illustrated example, it is a matrix of LEDs without the invention being limited to this example. The matrix light source can also be produced by a micro-mirror device, for which each mirror is adapted to generate an elementary light beam of a matrix.The module comprises a data receiving and sending unit 120, for example an interface capable of receiving and decoding messages on a data bus internal to the motor vehicle, such as a CAN (“Controller Area Network”) type bus.

[0039] The data reception unit 120 is capable of receiving / sending data from / to at least one control module of the motor vehicle. The control module 20 comprises data 22 relating to the motor vehicle, such as its attitude, the position of the lighting module in the motor vehicle, or others. The module 100 further comprises a memory element 140, such as a flash-type memory, to which the control unit 130 is functionally connected and has read access, and in which calibration data 150 specific to the matrix source 112 are recorded. By way of example, the data may comprise for each elementary light source 112 a value indicating the difference in brightness relative to the average brightness of the matrix source 110, possibly over a range of charging current intensities.The data 150 may nevertheless include more complex optical or geometric calibration parameters, without departing from the scope of the present invention.

[0040] The exchange of data between the light module 100 and the control module 20 of the motor vehicle when the two modules are paired allows for interesting applications. In particular, it is proposed to combine data relating to the vehicle 22, such as for example parameters of orientation, position, or attitude of the vehicle, or information relating to light fluxes emitted by other headlights of the vehicle, which are a priori only available at the level of the control module 20, with the calibration data 150, available at the level of the lighting module 100 and specific to the matrix source 110 embedded in it. This information is used, according to a preferred embodiment but in a non-limiting manner by the control module 20 of the motor vehicle to generate a default instruction or image 001.To do this, the relevant part of the calibration data 150 is first transmitted from the lighting module 100 to the control module 20, as indicated by the solid arrow in the . Figure 2 . In fact, the control module of the motor vehicle generally has an increased computing capacity compared to the control unit 130 of the lighting module.

[0041] Alternatively, this calculation can be carried out by the control unit 130 of the lighting module after a corresponding exchange of the data 22 required for this calculation between the control unit of the motor vehicle on the one hand, and the control unit of the lighting module on the other hand, represented by the dotted arrow of the figure 2 .

[0042] A default image is an image that is projected by the module when a fault or failure is detected. Thus, the module may preferably comprise an electronic error detection circuit (not shown), or a microprocessor programmed for this purpose by an appropriate computer program. The error detection circuit is configured to detect, for example, that the data received by the control module of the motor vehicle is inconsistent, or that the connection between the control module of the motor vehicle and the lighting module 100 is no longer reliable. Following this error detection, the default image 001 is projected instead of the current setpoint image, in order to avoid potential dazzling of other road users. The default image is generated to take into account the specificities of the matrix light source 110 on the one hand, and of the vehicle with which it is fitted on the other hand.Thus, the default image can, for example, be generated accurately and automatically for each motor vehicle and each lighting module fitted to it. Preferably, the default image resulting from this method is transmitted to the lighting module, which stores it permanently in a dedicated memory element. In the event of a communication failure between the control module 20 of the motor vehicle and the lighting module 100, the default setpoint then serves as a command to the matrix light source. The default image or setpoint may, for example, correspond to dipped beam lighting. In particular, this image may correspond to a dipped beam cutoff. Indeed, the cutoff must be well defined to comply with the regulations in force.The precise generation of the default instruction, taking into account all the parameters described, makes it possible in particular to prevent other road users from being dazzled when the default instruction is projected by the lighting module.

[0043] According to a preferred embodiment, in the absence of a fault and following pairing between the motor vehicle and the lighting module, the control module 20 can for example send an ignition instruction to the lighting module 100, which is responsible for controlling the matrix light source according to the instruction received. Such an instruction can for example comprise a brightness value, such as a gray level, encoded on a predetermined number of bits and to be produced by each of the elementary light sources 112. The ignition instruction can therefore be a digital image, and it can in particular be a frame of a stream of such images, constituting a video signal. The control unit 130 is intended to control said matrix light source according to said lighting instruction.The control unit may be connected to, or comprise, a circuit for controlling the electrical power supply of the elementary light sources 112, which is controlled to power the elementary light sources so as to achieve the lighting setpoint.

[0044] In order to guarantee a homogeneous light intensity, the control unit 130 adjusts the setpoint values received by the control module 20 by adding or subtracting the respective differences described in the calibration data 150, before controlling the elementary light sources in accordance with the result. The data 150 may nevertheless comprise more complex optical or geometric calibration parameters, without departing from the scope of the present invention. In such a case, instead of acting solely at the level of each light source or each pixel individually, the correction of the original setpoint can advantageously generate a correction at the level of the entire setpoint, i.e. of the entire image to be projected, or at the level of at least one part or zone of this image.For example, the projected image without the target correction could have a concave curved appearance due to the projection optics at the edges of the projection area. The realization of the pre-corrected target, which takes into account the calibration data including the geometric distortion inflicted by the projection optics, results in a projected image having a geometry closer to the desired uncurved geometry. To apply a correction for geometric aberrations, it is useful to apply a distortion to the entire original target image. Since it is discretized, this distortion causes a degradation of the information contained in the initial image. It is therefore advantageous for the cosign image transmitted from the vehicle control unit to the control unit to have a higher resolution than the projection resolution of the light module.

[0045] The control unit 130 comprises a microcontroller element having sufficient computing power to correct the setpoint 10, or a stream of setpoints, in real time, by applying the calibration data 150 to it.

[0046] According to a preferred embodiment of the invention, the lighting module is arranged to transmit at least part of the calibration data 150, and preferably all of this data, to the control module 20. This is for example carried out during an initialization phase of the lighting module. In order to guarantee a homogeneous light intensity, the control module 20 takes into account the calibration values 150 thus received to determine the setpoint image. For example, the control module 20 adjusts the setpoint values by adding or subtracting the respective differences, before transmitting the result to the lighting module 100. The data 150 may nevertheless comprise more complex optical or geometric calibration parameters, without departing from the scope of the present invention.In this embodiment, the control unit 1230 is freed from the task of correcting the setpoint, and it can be carried out by a less expensive microcontroller element with less computing power.

[0047] The data exchange between the control module 20 of the motor vehicle and the lighting module 100 previously defined also makes it possible to add an authentication function between the two modules 20 and 100 respectively.

[0048] It should be noted that this authentication function can also be implemented independently of the calibration function and / or the exchange of calibration / attitude data and without the presence of the memory element 140 at the level of the lighting module 200.

[0049] The authentication function may for example comprise the exchange of public cryptographic keys between the two modules in question, thus allowing verification by each of the authenticity of signed data using the corresponding private cryptographic keys. Alternatively or cumulatively, the control unit 130 of the lighting module 100 sends an acknowledgment of receipt to the control module 20 for a received data packet, the acknowledgment of receipt comprising a part making it possible to authenticate the microcontroller. The data packet may for example contain calibration data, and / or default image data and / or data for generating a default image and / or all or part of an image and / or a group of images, and / or a packet of a compressed video stream. In a preferred embodiment, this authentication is not performed on all the packets.In this way, the corresponding computational load is reduced and smoothed over time. Alternatively, the authentication function may comprise sending, from the control module 20 of the motor vehicle to the control unit 130 of the lighting module, a header for a sent data packet, the header comprising a part making it possible to authenticate the control module 20, the data packet being of the same type as previously defined. Advantageously, this authentication is not carried out on all the packets. In this way, the corresponding computational load is reduced and smoothed over time.

[0050] In order to carry out the authentication function, the lighting module 100 as well as the control module 20 of the motor vehicle comprise calculation means for generating the header respectively the acknowledgment of receipt used for authentication. Preferably, the generation is done according to of a time or date, which can be expressed in any unit of time, for example in milliseconds, or of a counter counting exchanges or calculation cycles, or of another element which evolves with the number of exchanges, which can be reset when it exceeds a predefined size.

[0051] In the event that authentication between the controller and the microcontroller fails, the lighting function can be put into a communication failure mode. Advantageously, the failure mode is only activated when authentication failures are repeated, which makes it possible to avoid activating the failure mode if the link has been disturbed, for example by transient electromagnetic disturbances, which is particularly advantageous in the case of an authentication function using headers or acknowledgments.

[0052] In the case where the control unit 130 comprises a computer, it can implement a data exchange encryption function, in which data encrypted by the control module 20 of the motor vehicle are decrypted by the computer. Advantageously, the computer has a method for determining whether the stream is not decoded correctly. If the stream is not decoded correctly, the computer can enter a communication failure mode. The communication failure mode can involve the following procedures, taken alone or in combination: stopping the lighting function or the projection by the lighting module of a default image, the generation by the control module 20 of a failure signal transmitted to a central management system of the automobile, the passage of the calculator into an authentication mode where the calculator continues to launch an authentication procedure with the calculator of the control module 20 (or vice versa). In the authentication mode, the sending of data packets can be interrupted.

[0053] It goes without saying that the embodiments described do not limit the scope of protection of the invention. By using the description just given, other embodiments are conceivable without departing from the scope of the present invention.

[0054] The scope of protection is determined by the claims.

Claims

1. Method for generating a default lighting instruction (001) for a lighting module (100) for a motor vehicle, the lighting module comprising a matrix light source (110) grouping together a plurality of elementary light sources (112), a data reception and transmission unit (120) for receiving / sending data from / to a control module (20) of the motor vehicle, the control module (20) comprising first data (22) relating to the motor vehicle, the lighting module further comprising a control unit (130) intended to control said matrix light source, and a memory element (140) comprising second calibration data (150) relating to said matrix light source, characterized in that the default instruction is intended to serve as a command for the matrix light source in case of communication failure between the control module (20) of the motor vehicle and the lighting module (100), and in that the method comprises the steps of a) calculating, by means of a calculation unit, a default lighting instruction, using at least a part of said first data and at least a part of said second data; b) recording the default lighting instruction in a memory element of the lighting module.

2. Method according to the preceding claim, characterized in that it comprises the preliminary step of sending at least a part of the second calibration data (150) by means of the data transmission unit (120) to the control module (20) of the motor vehicle, in that the calculation unit is part of said control module (20), and in that the method further comprises, before step b), the transmission of the default lighting instruction from the control module (20) to the lighting module (100).

3. Method according to the preceding claim, characterized in that it comprises the step of recording, at the level of the control module (20), the received second calibration data (150) in a memory element, in order to reuse them later.

4. Method according to one of the preceding claims, characterized in that it comprises a subsequent step of sending a lighting instruction from the control module (20) to the lighting module (100), the transmitted lighting instruction taking into account said calibration data (150).

5. Method according to claim 1, characterized in that it comprises the preliminary step of receiving at least a part of the first data (22) relating to the motor vehicle by means of the data reception unit (120) from the control module (20) of the motor vehicle, and in that the calculation unit is part of said lighting module.

6. Method according to the preceding claim, characterized in that it comprises a subsequent step of receiving a lighting instruction from the control module (20) at the level of the lighting module, and a step of controlling, by means of the control unit (130) of the lighting module (100), the matrix light source (110) according to said lighting instruction and the calibration data (150) stored in the memory element (140) of the module.

7. Method according to the preceding claim, characterized in that it comprises a step of correcting the received lighting instruction, using the calibration data (150) stored in the memory element (140) of the lighting module.

8. Method according to one of the preceding claims, characterized in that it comprises a subsequent step of detecting, by means of a detection unit, a fault at the level of the control module (20) and / or at the level of the lighting module (100), and of controlling the matrix source subsequently using said default instruction (001).

9. Method according to one of the preceding claims, characterized in that the first data (22) relating to the motor vehicle comprise data describing the attitude, the position of the lighting module, the position of other lighting modules, or a combination thereof.

10. Method according to one of the preceding claims, characterized in that the second calibration data (150) comprise for each elementary source an indication of the luminous intensity emitted as a function of an electric charge current, an indication of a geometric aberration of a light beam that the lighting module (100) is capable of emitting, or a combination thereof.

11. Method according to one of the preceding claims, characterized in that the default lighting instruction (001) comprises an image representing a dipped beam cutoff.

12. Method according to one of the preceding claims, characterized in that at least a part of the data exchanged between the control module (20) of the motor vehicle and the control unit (130) of the lighting module (100) is encrypted and / or signed by means of at least one cryptographic key.

13. Method of control according to the preceding claim, characterized in that a failure at the level of the lighting module (100) and / or the control module (20) of the motor vehicle is detected when the decryption of the data fails or when said signature cannot be validated.

14. Lighting system for a motor vehicle, characterized in that the system comprises a control module (20) of a motor vehicle, the control module (20) comprising first data (22) relating to the motor vehicle, the control module (20) being connected by a data channel to a lighting module which comprises a control unit (130) and a matrix light source (110) as well as a memory element (140) comprising second calibration data (150) relating to said matrix light source (110), and characterized in that the control module (20) and the lighting module (100) are configured to implement the steps of the method according to one of the preceding claims.