Device and method for controlling matrix light source

Abstract

A lighting module (100, 200) for a motor vehicle comprises a matrix light source (110, 210) grouping together a plurality of elementary light sources (112, 212) and a control module (130, 230) for the motor vehicle. The method for controlling the matrix source of said module is noteworthy in that it allows the generation of a default lighting set point (10).

Description

Technical Field

[0001] The present invention relates to a lighting module for a motor vehicle. In particular, the present invention relates to such a module involving a matrix light source. Background Art

[0002] A light emitting diode (LED) is a semiconductor electronic component that is able to emit light when it is subjected to an electric current with at least a threshold intensity. In the automotive sector, LED technology is increasingly used for numerous light signal solutions. LED matrices are of particular interest in the field of automotive lighting. Matrix light sources can be used for functions of the “leveling” type, i.e. to adjust the height of the emitted light beam according to the attitude of the vehicle and the contour of the road. Other applications include: DBL (“digital bending light”), which corresponds to adjusting the direction of the emitted light beam so as to follow the road in a horizontal plane; ADB (“adaptive drive beam”), which corresponds to the anti-glare function, which generates a shadow area in the beam emitted by the high beam in order not to disturb other road users, and the function of projecting a pattern on the ground using a pixelated light beam.

[0003] For the above-mentioned lighting applications, it is a known practice to use light sources with different types of technology. This can include, for example, monolithic technology, according to which a large number of LED-type basic sources (equivalent to pixels) are etched into a common semiconductor substrate. Integrated electrical connections allow pixels to be enabled independently of each other. Another known technology is micro-LED technology, which produces a matrix of LEDs of small size, typically less than 150 μm. There is also a micro-mirror module or DMD ("digital micro-mirror device") type, which involves projection technology using an intensity modulator on a uniform light beam. The micro-mirrors whose positions are controlled by piezoelectric elements are oriented to selectively reflect the incident light beam so that each micro-mirror corresponds to the basic source of the pixel matrix thus generated. The light from the source is directed to the micro-mirror matrix through an optical device. Due to the positioning and manufacturing tolerances of the optical device and the light source, this light has a variable distribution between modules. For a given pixel, this causes a variable maximum intensity between modules. In this case, each pixel will have a different maximum intensity depending on the command sent to it. This lighting device is designed using a mass production method. On the one hand, there must be a certain amount of play between the constituent elements of the lighting and / or signaling device in order to facilitate assembly, and on the other hand, since these parts are usually not machined but moulded from plastic, this allows production costs to be reduced.

[0004] It is worth emphasizing that it is difficult to perfectly align the micromirror matrix with the optical projection part, which usually includes at least one lens. Since the lenses used for the projection function have a high numerical aperture, the projection quality of the image is significantly reduced if the lateral offset from the optical axis reaches several micrometers. Therefore, in practice, distortion of the projected image is inevitable using solutions known in the prior art. Each projection module of this type has its own set of optical properties, in particular geometric aberration properties, including optical distortion and spherical aberration properties. During the production process of the micromirrors, geometric aberrations may be introduced. All these elements cause inhomogeneous behavior of the matrix light source.

[0005] All of these modules have their own characteristics related to the combination of manufacturing tolerances of the components. During the production of semiconductor components such as LEDs or LED matrices, DC current variations are currently unavoidable. As a result, for the same load current, in a given LED matrix, the LEDs emit light beams with variable, non-uniform intensity. Summary of the invention

[0006] An object of the present invention is to overcome at least one of the problems posed by the prior art. More precisely, the object of the present invention is to propose a lighting module and a control method which make it possible to calibrate the luminous and / or geometrical behavior of elementary light sources grouped together in a matrix light source for a motor vehicle. The object is to provide means for generating a uniform light beam conforming to a predetermined set point, independently of the instance of the matrix light source installed in the lighting module.

[0007] According to a first aspect of the invention, a lighting module for a motor vehicle is proposed. The lighting module comprises a matrix light source grouping together a plurality of elementary light sources, a data receiving unit for receiving lighting set points, and a control unit intended to control the matrix light source according to the lighting set points. The lighting module is noteworthy in that it comprises a storage element, the control unit has read access to the storage element, and the storage element stores calibration data specific to each elementary light source.

[0008] The receiving unit may preferably include a network interface capable of receiving data via a data bus inside the motor vehicle. For example, the bus may be an Ethernet bus, a Gigabit Multimedia Serial Link (GMSL) type bus, or a bus using a low voltage differential signal (LVDS) technology, such as a FPD-Link III bus.

[0009] The control unit may preferably include a microcontroller element. The control unit may preferably include 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 using an appropriate computer program to implement the described functions.

[0010] The matrix light source may preferably comprise a monolithic source comprising elementary luminescent light sources with semiconductor elements which are etched into a common substrate and can be activated independently of each other.

[0011] The matrix light source may preferably comprise a micro-LED type matrix comprising an elementary source matrix produced by light emitting diodes (LEDs) of small size, typically less than 150 μm.

[0012] The matrix light source may preferably comprise a micromirror device DMD (Digital Micromirror Device), wherein the elementary sources comprise micromirrors in a matrix which selectively reflect an incident light beam depending on their position.

[0013] Preferably, the lighting set points may comprise a primary set point for each primary light source.

[0014] The lighting setpoint may preferably comprise an image. Preferably, at least one pixel of the image may correspond to one elementary light source. The resolution of the image may preferably be higher than the projection resolution of the matrix light source. Preferably, one pixel of the image may correspond to one elementary light source.

[0015] Preferably, the calibration data may comprise, for each elementary source, an indication of the intensity of light emitted as a function of the electrical load current.

[0016] Preferably, the calibration data may include an indication of the geometrical aberrations of the light beam that the module is capable of emitting.

[0017] The control unit may preferably be configured to control said matrix light source by correcting said illumination set point by utilizing at least some of said calibration data.

[0018] Preferably, the control unit may be configured to send at least some of said calibration data to a control module for a motor vehicle.

[0019] The lighting module may preferably comprise a second storage element in which data allowing the module to be authenticated are stored.Preferably, the lighting module may comprise a processor programmed to encrypt and / or sign data by means of an encryption key stored in said storage element.

[0020] According to another aspect of the present invention, a lighting device for a motor vehicle is proposed. The device is noteworthy in that it comprises at least one lighting module according to the previous aspect of the present invention.

[0021] According to another aspect of the present invention, a method for controlling a matrix light source of a lighting module for a motor vehicle is provided. The lighting module is according to one aspect of the present invention. The method is notable in that it comprises the following steps:

[0022] a) at a control module for a motor vehicle, determining a lighting set point;

[0023] b) At a control unit for the lighting module connected to the control module via a communication channel, controlling the matrix light source of the lighting module in dependence on said lighting set points and the calibration data stored in a memory element of the module.

[0024] Preferably, the method may include the following steps between step a) and step b):

[0025] aa) at a control module for a motor vehicle, sending said lighting set point to a control unit for the lighting module;

[0026] And preferably, step b) may further include:

[0027] bb) At a control unit for a lighting module, receiving said lighting set point and correcting the set point by using calibration data stored in a memory element of the module.

[0028] Preferably, the calibration data may comprise a light intensity value for each elementary light source.

[0029] Preferably, the method may include the following preliminary steps:

[0030] i) at a control unit for the lighting module, sending at least some of the calibration data stored in the storage element to a control module for the motor vehicle;

[0031] And step a) may include:

[0032] aaa) At a control module for a motor vehicle, the determined set point is corrected by using the received calibration data and said corrected lighting set point is sent to a control unit for the lighting module.

[0033] Preferably, at least some of the calibration data sent to a control module for a motor vehicle may comprise data indicative of geometrical aberrations.

[0034] The control method may preferably comprise the step of generating a default lighting set point determined by using said calibration data and data relating to the motor vehicle, and storing the default lighting set point in a memory element of the lighting module.

[0035] Preferably, said default lighting set point may be generated by a control module for a motor vehicle after receiving said calibration data from a control unit for a lighting module.The set point may then preferably be sent to said control unit which stores the set point in a memory element.

[0036] If a fault is detected at a lighting module and / or a control module for a motor vehicle, a default set point may preferably replace the lighting set point received in step a).

[0037] Preferably, at least some of the data exchanged between the control module for the motor vehicle and the control unit for the lighting module can be encrypted and / or signed by means of at least one encryption key.

[0038] Preferably, a fault can be detected at a lighting module and / or a control module for a motor vehicle when decryption of the data is unsuccessful or when the signature cannot be verified.

[0039] According to another aspect of the present invention, a method for pairing a lighting module for a motor vehicle according to one aspect of the present invention with a control module for a motor vehicle is proposed. The method is notable for comprising the following steps:

[0040] - at a control unit for the lighting module, sending the calibration data stored in the storage element to a control module for the motor vehicle;

[0041] - generating, at the control module, a default lighting set point by using data relating to the motor vehicle, such as, for example, the attitude, position of the lighting module or the position of other lighting modules, and sending it to a control unit for the lighting module;

[0042] - At a control unit for the lighting module, a default set point is saved in a memory element.

[0043] Preferably, the default set point may comprise an image corresponding to low beam headlamp illumination. Preferably, the default set point may comprise a low beam headlamp cut-off.

[0044] According to another aspect of the invention, a computer program is proposed comprising a sequence of instructions. When the instructions are executed by a processor, they cause the processor to carry out a method according to one of the aspects of the invention.

[0045] According to a final aspect of the present invention, a non-transitory computer-readable storage medium is provided, wherein the medium stores a computer program according to an aspect of the present invention.

[0046] By using the measures proposed by the invention, it is possible to provide a lighting module and a control method that make it possible to calibrate the luminous and / or geometrical behavior of elementary light sources grouped together in a matrix light source of a lighting module of a motor vehicle. These aspects of the invention make it possible to produce a uniform light beam that complies with a predetermined set point, regardless of the instance of the matrix light source installed in the lighting module. In order to achieve this, according to an aspect of the invention, it is proposed to store calibration parameters in a memory attached to the lighting module, the parameters including, for example, current or brightness correction values ​​for each pixel of the matrix source, or a geometric correction of the light beam produced by the light module. In this way, it is ensured that the data related to the module are physically attached to the module, in particular when pairing the lighting module with a motor vehicle. This makes it possible to avoid additional steps that could lead to erroneous parameterization when assembling a vehicle headlamp using the lighting module. By using the measures of the invention, it is possible to assemble or change the module without software operations: for example, it is not necessary to transfer or update the data related to the module in the memory of a controller for a motor vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Other characteristics and advantages of the invention will be better understood with the aid of the description given with the aid of examples and the accompanying drawings, in which:

[0048] - Figure 1 is a diagram of a lamp module according to a preferred embodiment of the present invention;

[0049] - Figure 2 is a diagram of a lamp module according to a preferred embodiment of the present invention;

[0050] - Figure 3 shows the sequence of the main steps of the method according to a preferred embodiment of the present invention;

[0051] - Figure 4 The sequence of the main steps of the method according to a preferred embodiment of the present invention is shown. DETAILED DESCRIPTION

[0052] Unless otherwise stated, 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 not limitation. Similar reference numerals will be used to describe similar concepts in various embodiments of the present invention. For example, reference numerals 100 and 200 represent two embodiments of lighting modules according to the present invention.

[0053] The description focuses on the elements of a lighting module for a motor vehicle that are necessary for understanding the invention. Other elements that form part of such a module in a known manner will not be mentioned or described in detail. For example, the existence and operation of a converter circuit involved in supplying power to a matrix light source, which is known per se, will not be described in detail. The same applies to optical elements such as lenses, for example.

[0054] Figure 1The diagram of shows a lighting module 100 for a motor vehicle according to a first embodiment. The module comprises a matrix light source 110 which groups together a plurality of elementary light sources 112. In the example shown, this is an LED matrix, however, the invention is not limited to this example. The matrix light source can also be generated by a micromirror device, for which each mirror is designed to generate one elementary light beam of the matrix. The module comprises a data receiving unit 120; this is an interface capable of receiving and decoding messages, for example, via a data bus such as a CAN (Controller Area Network) bus, internal to the motor vehicle. The data receiving unit 120 is capable of receiving a lighting set point 10, typically determined by a control module (not shown) of the motor vehicle. The lighting set point can, for example, comprise a brightness value, such as a grayscale level, generated by each elementary light source 112, encoded on a predetermined number of bits. The lighting set point can thus be a digital image, and it can in particular be a frame from such an image stream, constituting a video signal. The control unit 130 is intended to control the matrix light source according to the lighting set point. The control unit may be connected to or include a circuit for driving an electric power supply for the elementary light sources 112, the circuit being controlled so as to supply power to the elementary light sources in such a way as to achieve the set point 10. The module 100 further includes a storage element 140, such as a flash memory, to which the control unit 130 is functionally connected and has read access, and in which calibration data 150 specific to each elementary light source 112 are stored. By way of example, for each elementary light source 112, the data may include a value indicating a brightness difference relative to the average brightness of the matrix source 110, possibly within a range of load current intensities. To ensure uniform light intensity, the control unit 130 adjusts the received set point value 10 by adding or subtracting the corresponding difference to the control unit before controlling the elementary light sources according to the result. However, the data 150 may include more complex optical or geometric calibration parameters without thereby departing from the scope of the invention. In this case, instead of acting only at the level of each light source individually or at the level of each pixel, the correction of the set point 10 may advantageously produce a correction at the level of the entire set point, i.e. at the level of the entire image to be projected, or at the level of at least a portion or region of this image. For example, an image projected without set point correction may present a concave curved appearance due to the projection optics near the projection area. Generating a pre-corrected set point (which takes into account the calibration data, including the geometric deformation imposed by the projection optics) causes the projected image to present a geometry that is closer to the desired non-curved geometry. In order to correct for the geometric aberrations, a deformation is applied to the entire set point image 10. Since this is discretized, this deformation causes a degradation of the information contained in the initial image. It is therefore advantageous that the reference image sent from the control unit of the vehicle to the control unit has a higher resolution than the projection resolution of the light module.The control unit 130 comprises a microcontroller element having sufficient computing power to correct the set point or the set point flow in real time by applying calibration data 150 to the corrected set point 10 or the set point flow.

[0055] Figure 2 The diagram of shows a lighting module 200 for a motor vehicle according to a second embodiment. The module comprises a matrix light source 210 grouping together a plurality of elementary light sources 212. The module comprises a data receiving / transmitting unit 220, 222. The data receiving unit 220 is capable of receiving a lighting set point 10 typically determined by a control module 20 of the motor vehicle. For example, the lighting set point may comprise a brightness value, such as a grayscale level, encoded on a predetermined number of bits generated by each elementary light source 212. The control unit 230 is intended to control the matrix light source according to the lighting set point. The module 200 further comprises a storage element 240, such as a flash type memory, to which the control unit 230 is functionally connected and read-accessible, and in which calibration data 250 described in the context of the previous embodiment and specific to each elementary light source 212 are stored. By way of example, for each elementary light source 212, the data may comprise a value indicating a brightness difference relative to the average brightness of the matrix source 210, possibly within a range of load current intensities. The illustrated lighting module is arranged to send at least some calibration data 250 and preferably all of this data to the control module 20. This is performed, for example, in a phase of initialization of the lighting module. In order to ensure uniform light intensity, the control module 20 takes into account the calibration values ​​250 thus received to determine the set point image 10. For example, the control module 20 adjusts the set point value 10 by adding or subtracting the corresponding difference before sending the result to the lighting module 200. However, the data 250 may include more complex optical or geometric calibration parameters without thereby departing from the scope of the present invention. In this embodiment, the control unit 230 is relieved of the task of correcting the set point, and it can be performed by a cheaper microcontroller element with less computing power.

[0056] Figure 3 Schematically shows the Figure 1 The control method is performed in the first embodiment described. In step a), the lighting set point 10 is determined by the control module of the motor vehicle and sent to the lighting module, which corresponds to step a1). Upon receiving the set point 10, the control unit 130 controls the matrix light source 110 while correcting the set point 10 using the calibration data 150 stored in the storage element 140, which corresponds to step b).

[0057] Figure 4 Schematically shows the Figure 2The control method according to the second embodiment described is implemented. In a preliminary step i), at least some of the calibration data 250 stored in the storage element 240 are sent from the lighting module 200 to the control module 20 of the motor vehicle. In step a), the lighting set point 10 is determined by the control module of the motor vehicle and corrected according to the received calibration data 250 and sent to the lighting module, which corresponds to step a2). In step b), the control unit 230 of the lighting module 200 controls the matrix light source 210 of the lighting module according to said lighting set point, which now depends on the calibration data 250 stored in the storage element 240.

[0058] The data exchange between the light module 200 and the control module 20 of the motor vehicle after pairing these two allows other advantageous applications. In particular, it is proposed to combine data related to the vehicle, such as, for example, the orientation, position or attitude parameters of the vehicle, or information about the luminous flux emitted by other headlights of the vehicle, which are a priori available only at the control module 20, with calibration data 250, which are available at the lighting module 200 and are specific to the matrix source 210 installed therein. This information is typically, but in a non-limiting manner, used by the control module 20 of the motor vehicle to generate a default image or set point. In particular, the control module of the motor vehicle usually has greater computing power than the control unit 230 of the lighting module. Alternatively, this calculation can be performed by the control unit 230 of the lighting module, after a corresponding exchange of the data 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. The default image is the image projected by the module when a fault or failure is detected. Therefore, the module can preferably include an electronic error detection circuit, or a microprocessor programmed for this purpose by a suitable computer program. The error detection circuit is configured to detect, for example, that the data received by the control module of the motor vehicle are inconsistent, or that the connection between the control module of the motor vehicle and the lighting module 200 is no longer reliable. After detecting this error, a default image is projected instead of the set point image, with the aim of avoiding potential dazzling of other road users. The default image is generated to take into account the characteristics of the matrix light source 210 on the one hand and the characteristics of the vehicle equipped with it on the other hand. Thus, for example, a default image can be accurately and automatically generated for each motor vehicle and each lighting module with which the vehicle is equipped. Preferably, the default image generated by this method is sent to the lighting module, which stores the default image permanently in a dedicated storage element. In the event of a communication failure between the control module 20 of the motor vehicle and the lighting module 200, the default set point is then used to control the matrix light source. The default set point or image may, for example, correspond to low-beam headlamp lighting. In particular, this image may correspond to a low-beam headlamp cutoff. In particular, the cutoff must be clearly defined in order to meet current regulations.

[0059] As defined above and Figure 4 The data exchange shown between the control module 20 and the lighting module 200 of the motor vehicle also allows the addition of an authentication function between the two modules 20 and 200 , respectively.

[0060] It should be noted that this authentication functionality may also be implemented independently of the calibration functionality and / or independently of the exchange of calibration / gesture data and without the presence of the storage element 240 at the lighting module 200 .

[0061] The authentication function may, for example, consist of exchanging a public encryption key between the two modules in question, thereby allowing mutual verification of the authenticity of the data signed by the corresponding private encryption key. Alternatively or additionally, the control unit 230 of the lighting module 200 sends a receipt confirmation to the control module 20 for a received data packet, the receipt confirmation comprising a portion allowing the microcontroller to be authenticated. The data packet may, for example, contain calibration data and / or default image data and / or data for generating all or part of a default image and / or an image and / or a group of images and / or a packet from a compressed video stream. In a preferred embodiment, this authentication is not performed for all packets. In this way, the corresponding computational load is lightened and smoothed over time. Alternatively again, the authentication function may consist of sending a header for a data packet to be sent from the control module 20 of the motor vehicle to the control unit 230 of the lighting module, the header comprising a portion allowing the control module 20 to be authenticated, the data packet being of the same type as defined above. Advantageously, this authentication is not performed for all packets. In this way, the corresponding computational load is lightened and smoothed over time.

[0062] In order to perform the authentication function, the lighting module 200 and the control module 20 of the motor vehicle comprise computing means for generating a header for authentication or a receipt confirmation, respectively. Preferably, the generation is performed according to the following:

[0063] A time or date can be expressed in any time unit, such as milliseconds, or

[0064] A counter counts switches or counts cycles, or

[0065] Other elements vary with the number of swaps and may be reset when they exceed a predetermined size.

[0066] In the event of an authentication failure between the controller and the microcontroller, the lighting function can enter a communication failure mode. Advantageously, the failure mode is only enabled in the event of repeated authentication failures, which makes it possible to avoid enabling the failure mode in the event that the link has been interrupted, for example due to transient electromagnetic interference, which is particularly advantageous in the case of authentication functions using headers or receipt confirmations.

[0067] In the case where the control unit 230 comprises a computer, it can implement a data exchange encryption function, wherein the data encrypted by the control module 20 of the motor vehicle is decrypted by the computer. Advantageously, the computer has a method for determining whether the stream has not been correctly decoded. If the stream has not been correctly decoded, the computer can enter a communication failure mode. The communication failure mode can involve the following procedures alone or in combination:

[0068] - Stop the lighting function or lighting module from projecting a default image,

[0069] - the control module 20 generates a fault signal which is sent to the central management system of the vehicle,

[0070] The computer enters an authentication mode in which it continues to initiate an authentication procedure with respect to the computer of the control module 20 (or vice versa). In authentication mode, the sending of data packets may be interrupted.

[0071] It goes without saying that the described embodiments do not limit the scope of protection of the invention. By referring to the description just given, other embodiments can be envisaged without departing from the scope of the invention.

[0072] The scope of protection is defined by the claims.

Claims

1. A lighting module (100, 200) for a motor vehicle, comprising a matrix light source (110, 210) grouping together a plurality of elementary light sources (112, 212), a data receiving unit (120, 220) for receiving a lighting set point (10), and a control unit (130, 230) intended to control the matrix light source according to the lighting set point, characterized in that The module comprises a storage element (140, 240), the control unit (130, 230) having read access to the storage element and having stored therein calibration data (150, 250) specific to each of the elementary light sources (112, 212), the control unit (230) being configured to send at least some of the calibration data (250) to a control module (20) for the motor vehicle, the control module being configured to generate a default lighting set point determined by using the calibration data and data related to the motor vehicle, wherein the default lighting set point is stored in the storage element of the lighting module.

2. The lighting module according to claim 1, characterized in that: The lighting set points include a primary set point for each primary light source.

3. The lighting module according to claim 2, characterized in that: The lighting set point includes an image, at least one pixel of the image corresponding to a primary light source (112, 212).

4. The lighting module according to any one of claims 1 to 3, characterized in that: For each elementary light source, the calibration data (150, 250) comprises an indication of the intensity of light emitted as a function of the load current and / or an indication of the geometrical aberrations of the light beam that each elementary light source is able to emit.

5. The lighting module (100, 200) according to any one of claims 1 to 3, characterized in that: The module comprises a second storage element storing therein data allowing the module to be authenticated.

6. A method for controlling a matrix light source of a lighting module (100, 200) for a motor vehicle according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: a) determining, at a control module (20) for said motor vehicle, a lighting set point (10); b) at the control unit (130, 230) for the lighting module connected to the control module (20) via a communication channel, controlling the matrix light source (110, 210) of the lighting module according to the lighting set point and calibration data (150, 250) stored in a memory element (140, 240) of the module.

7. The control method according to claim 6, characterized in that: The method comprises the following preliminary steps: i) at the control unit (230) for the lighting module, sending at least some of the calibration data (250) stored in the storage element (240) to the control module (20) for the motor vehicle; And step a) comprises: aaa) At the control module (20) for the motor vehicle, the determined set point is corrected by using the received calibration data and the corrected lighting set point (10) is sent to the control unit (230) for the lighting module.

8. The control method according to claim 6, characterized in that: The method comprises the steps of generating a default lighting set point determined by using the calibration data and data relating to the motor vehicle, and storing the default lighting set point in a memory element of the lighting module.

9. The control method according to claim 8, characterized in that: The default lighting set point is generated by the control module for the motor vehicle after receiving the calibration data from the control unit for the lighting module, and the set point is then sent to the control unit which stores the set point in a storage element.

10. The control method according to claim 8, characterized in that: If a fault is detected at the lighting module and / or the control module for the motor vehicle, the default set point replaces the lighting set point received in step a).

11. The control method according to claim 6, characterized in that: At least some of the calibration data exchanged between the control module for the motor vehicle and the control unit for the lighting module are encrypted and / or signed by means of at least one encryption key.

12. The control method according to claim 11, characterized in that: When the decryption of the data is unsuccessful or when the signature cannot be verified, a fault is detected at the lighting module and / or the control module for the motor vehicle.

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