Voltage control method for a pixelated light source

Abstract

The invention proposes a method for controlling a pixelated light source for a motor vehicle which is voltage-driven. The method makes it possible to avoid risks of thermal runaway of the elementary pixels of the source independently of the projected photometries. By dynamically adapting the electrical current intensities at the level of the elementary light sources, the control method allows the protection of the semiconductor junctions of the pixels of the pixelated light source, to increase their lifetime and to avoid visible defects at the level of a beam projected on the road following a thermal runaway. Figure for the abstract: Fig. 1

Description

Title of the invention: Voltage control method for a pixelated light source

[0001] This invention relates to the field of motor vehicle lighting systems, and in particular it relates to such systems using voltage-controlled light sources.

[0002] A light-emitting diode, LED, is a semiconductor electronic component capable of emitting light of a predetermined wavelength when an electrical voltage at least equal to a threshold value is applied to its terminals. Beyond this threshold value, called forward voltage, the intensity of the luminous flux emitted by an LED generally increases with the average intensity of the supply electric current. With heating of the semiconductor junction, the intensity of the electric current tends to increase at a constant applied voltage. Their small size and low power consumption make LED components interesting in the field of light modules for motor vehicles. LED-type light sources can, for example, be used to produce distinctive optical signatures by placing the components along predetermined contours.By using LED components, the creation of lights with multiple lighting functions is also facilitated.

[0003] It is also known to use pixelated light sources of different types of technologies to project these light beams from image data. This is for example the monolithic technology, according to which a large plurality of elementary sources of the light-emitting diode, LED, type, equivalent to pixels, are etched in a common semiconductor substrate. The substrate can also comprise embedded electronic components, such as switch circuits or others. Integrated electrical connections make it possible to activate the pixels independently of each other. It has in particular been proposed to control such pixelated light sources by voltage: by applying a constant electrical voltage to a pixelated light source, the individual pixels can be controlled by means of a switch per pixel, controlled by a binary signal.The control signal targeting a pixel can, for example, be a pulse width modulation (PWM) signal, the duty cycle of which will have a direct impact on the average intensity of the electric current flowing through the pixel, and therefore on its degree of brightness.

[0004] Pixelated light sources can be used to perform “high beam” (HB) functions, or complex functions such as ADB ("Adaptive Driving Beam") or others. For voltage-controlled light sources, it is generally intended to provide a supply voltage with a constant value. However, at constant voltage, the intensity of the electric current flowing through a semiconductor junction, such as the junction of a light-emitting pixel, increases linearly with temperature. The junction temperature increases when an electric current flows through it. For pixels used for a long time, there is therefore a risk of thermal runaway: the more the semiconductor junction is heated by the electric current flowing through it, the more the intensity of the electric current increases, until the junction becomes faulty or is irreversibly destroyed.This risk is more pronounced for pixels in a central area of the pixelated light source that are involved in a plurality of lighting functions of a vehicle, and are therefore used more regularly. Failures in this area can lead to visible failures in the light beam projected onto the road. Since exact temperature measurement per pixel is not currently practicable, it is difficult to predict potentially overheated points on a pixelated light source that, in operating mode, is likely to project a series of different images.

[0005] The invention aims to overcome at least one of the problems posed by the prior art. More specifically, the invention aims to propose a method for controlling a voltage-driven pixelated light source, which makes it possible to avoid risks of thermal runaway of the elementary pixels of the source.

[0006] According to a first aspect of the invention, a method for controlling a pixelated light source for a motor vehicle is proposed. The pixelated light source is intended to be voltage-driven and comprises a plurality of elementary light sources with an electroluminescent semiconductor element. The method is remarkable in that it comprises at least the steps of:

[0007] i) controlling, by means of a control unit, the pixelated light source so as to project a light beam corresponding to image data, by providing it with a first level of electrical voltage, and by controlling each elementary light source by a direct current pulse width modulation signal which determines a first average intensity of the electrical current passing through it;

[0008] ii) obtaining, by means of a plurality of temperature sensors arranged at predetermined locations, a temperature profile of the pixelated light source;

[0009] iii) estimating, by means of the control unit, the position of a hot spot of the pixelated light source on the basis of the image data and the temperature profile obtained;

[0010] iv) estimating, by means of the control unit, a temperature value of said hot spot as a function of the temperature profile obtained and its estimated position relative to the locations of the temperature sensors;

[0011] v) modifying, by means of the control unit, the control of the pixelated light source so that each of the elementary light sources is crossed by an electric current of a second average intensity, lower than the first intensity, if the estimated temperature value is higher than a predetermined threshold temperature value.

[0012] Preferably, the step of estimating the position of a hot spot may comprise searching for the obtained temperature profile among a plurality of temperature profiles pre-stored in a memory element, each profile being associated with particular image data and a hot spot position associated with this data.

[0013] The step of estimating a temperature value of said hot spot may preferably comprise a step of incrementing at least one of the temperature values of the temperature profile obtained, using a predetermined increment which depends on the estimated position of the hot spot.

[0014] Preferably, the step of estimating a temperature value may further comprise taking into account the projected image data, a high brightness value of a pixel corresponding to a hot elementary light source.

[0015] The step of modifying the control may preferably comprise a step of providing a second electrical voltage level, lower than the first electrical voltage level, to the pixelated light source if the estimated temperature value is greater than a predetermined threshold temperature value.

[0016] Preferably, the step of modifying the command may comprise a prior step of comparing said estimated temperature value with said predetermined threshold temperature value, the predetermined threshold temperature value being dependent on the first level of electrical voltage supplied.

[0017] The method may preferably comprise a preliminary step of providing, in a memory element, reference data relating to the pixelated light source, which relate, for a range of operating temperatures of the pixelated light source, control voltage values with corresponding supply current intensities, and in that the step of modifying the control comprises the choice of the second electrical voltage level depending on the estimated temperature value, in order to comply with a predetermined threshold electrical current intensity.

[0018] The step of modifying the control may preferably comprise a step of controlling each elementary light source by a modulation signal of direct current pulse width which determines a second average intensity of the electric current flowing through it, the second average intensity being less than the first average intensity, if the estimated temperature is greater than a predetermined threshold temperature value.

[0019] According to another aspect of the invention, a lighting assembly for a motor vehicle is provided. It may for example be a light module. The assembly comprises a pixelated light source having a plurality of elementary light sources with an electroluminescent semiconductor element, the pixelated light source being intended to be voltage controlled, a plurality of temperature sensors intended to provide a temperature profile of the pixelated light source when it projects image data, and a control unit. The assembly is remarkable in that the control unit is configured to control the pixelated light source in dependence on an estimated temperature value of a hot spot of the pixelated light source, which depends on an estimated position of the hot spot and the image data.

[0020] Preferably, the control unit may be configured to perform the steps according to a method in accordance with one aspect of the invention.

[0021] The assembly may preferably comprise a memory element operatively connected to the control unit and comprising pre-recorded reference data relating to the pixelated light source.

[0022] The pixelated light source may preferably comprise at least one temperature sensor capable of providing a temperature indication to the control unit. The temperature profile may preferably comprise a temperature measurement or indication provided by each of the temperature sensors. Each temperature value of the temperature profile may preferably be associated with the position of the temperature sensor having carried out the measurement, relative to the pixelated light source.

[0023] By using the measures proposed by the present invention, it becomes possible to propose a method for controlling a pixelated light source for a motor vehicle which is voltage-controlled, which makes it possible to avoid risks of thermal runaway of the elementary pixels of the source, and this dynamically and independently of the images projected by the pixelated light source. By lowering the electrical supply voltage, or by reducing the average intensity of the electrical current at each pixel when a threshold temperature, preferably corresponding to a maximum threshold current intensity, is exceeded, the control method protects the semiconductor junctions of the pixels of the pixelated light source, to increase their lifetime and to avoid visible defects in a beam projected onto the road. A light module implementing the The proposed thermal control and regulation process therefore represents a more sustainable and more economical solution compared to known state-of-the-art products.

[0024] Other characteristics and advantages of the present invention will be better understood with the aid of the description of the examples and the drawings among which:

[0025] - [fig.l] is a diagram showing the main steps of a process according to a preferred embodiment of the invention;

[0026] - [fig.2] is a schematic illustration of a light assembly in accordance with a preferred embodiment of the invention;

[0027] - [fig.3] is a schematic illustration of image data and a source light that projects this image data, including temperature sensors, in accordance with a preferred embodiment of the invention;

[0028] - [fig.4] is a schematic illustration of image data and a source light that projects this image data, including temperature sensors, in accordance with a preferred embodiment of the invention;

[0029] - [fig.5] is an illustration of reference data of a pixelated light source as they are involved in a method in accordance with a preferred embodiment of the invention.

[0030] 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.

[0031] The description focuses on the elements of a control method and a lighting assembly for a motor vehicle, which are necessary for understanding the invention. Other elements, which are for example in a known manner part of such assemblies, will not be mentioned or described in detail. For example, the presence of a support or heat dissipation elements are implicit for the operation of such a module.

[0032] A light assembly or module for a motor vehicle as it is involved in the implementation of a control method in accordance with a first embodiment according to the invention makes it possible to project lighting functions from image data. The module comprises a light source capable of projecting a pixelated light beam. An image generally comprises a matrix of pixel values, each value corresponding to a degree of brightness to be achieved by a corresponding elementary light source of the lighting module. Generally, the pixelated light source is supplied with electrical voltage: at a given instant, the same electrical voltage is applied to the terminals of each pixel, which is equivalent to an elementary source produced by a miniaturized electroluminescent semiconductor element. The degree of brightness to be emitted by each pixel is controlled by the duty cycle of a pulse width modulation (PWM) control signal that selectively and periodically switches the pixel on and off. At a duty cycle of 100%, the average electrical current flowing through a pixel is equal to its maximum or peak intensity, resulting in maximum brightness. At lower intensity levels, a lower duty cycle results in a lower average value of the average electrical current flowing through the pixel. The maximum current intensity is dependent on the electrical voltage value applied to the pixelated light source.

[0033] [fig.l] shows the main steps of a control method according to a first embodiment of the invention. In a first step i, a first electrical voltage level is supplied to a pixelated light source intended to be voltage-controlled. The pixelated light source comprises a plurality of elementary light sources of the light-emitting diode type. Each elementary light source is intended to produce a luminous pixel of the image projected by the pixelated light source. Image data represent an image to be projected (for example a beam of a particular shape) and determine the degree of brightness (typically between 0 and 255) to be produced by each elementary light source. At equal electrical voltage and equal temperature, each elementary light source is powered by an electric current of the same intensity.This maximum intensity is reduced individually for each elementary light source, by applying a pulse width modulation signal of the direct current, provided by a control unit realized for example by a microcontroller element. The duty cycle of this signal directly impacts the average intensity of the intensity of the electric current which supplies an elementary light source, which is proportional to the emitted brightness. It is therefore assumed that the pixelated light source is supplied with an electric voltage having a first level, and that each elementary light source is supplied with an electric current of a first intensity, which determines the brightness of the projected pixel which corresponds to it.

[0034] In a second step ii, a plurality of temperature sensors arranged at predetermined locations near the matrix of elementary light sources provide an indication of their ambient temperature to the control unit. Then, the position of a hot spot of the pixelated light source is estimated based on the projected image data, which are available at the control unit, and using the temperature profile, which is composed of the obtained temperature measurements. Ideally, each sensor provides a measurement that is part of the obtained temperature profile. This corresponds to step iii. In the next step iv, the control unit evaluates a temperature value representing representative of the temperature of the hot spot thus determined. Ideally, this hot spot corresponds to the hottest point of the pixelated light source at the time of measurement: it is therefore the highest junction temperature among all the elementary light sources. If this temperature is higher than a predetermined threshold value, the control unit produces a command which aims to reduce the average intensity of the current which circulates in all the elementary light sources of the matrix, in order to guarantee the relative luminous differences between the projected pixels, while reducing the risk of thermal runaway (corresponding to linear overheating in time) for the elementary light sources at risk, i.e., those which are the hottest.

[0035] [Fig. 2] shows a lighting assembly 100 for a motor vehicle in accordance with a first embodiment. The illustrated system comprises a control unit 130 for a pixelated light source 110, for example of the monolithic type. The pixelated light source comprises a plurality of elementary light sources 112 arranged in the form of a matrix. The control unit may for example comprise, or control by means of an electrical connection, a circuit for controlling the electrical power supply of the pixelated light source 110. In a known manner, such control circuits may comprise voltage step-down converter circuits, for example of the “buck” type, and voltage step-up converter circuits, for example of the “boost” type. These circuits are per se known in the art and their operation will not be described in detail within the scope of the present invention.A converter circuit makes it possible in particular to convert an electrical voltage supplied to its input (not illustrated) into an output voltage Vout, determined by the control unit 130, and having a value different from the input voltage. Depending on the architecture chosen, the output voltage may be higher or lower than the input voltage. Such circuits are commonly used in the context of the electrical supply of light sources with electroluminescent semiconductor elements, for example of the light-emitting diode, LED type. Indeed, such light sources must be supplied with a voltage level at least equal to the value of their direct voltage, which may be different from the available voltage, for example supplied by a battery of a motor vehicle.

[0036] The pixelated light source 110 is supplied with electrical voltage and may comprise hundreds or thousands of pixels 112. The light intensities emitted by the individual pixels are controlled by periodic PWM on / off signals, as described above. The control unit has access to image data II, which correspond to at least one digital image, also called photometry. The photometries may be stored in a memory element to which the control unit has read access. Following a signal received from a control unit central control of the motor vehicle, the control unit then selects an appropriate photometry from a plurality of available photometries. It is also possible for the control unit 130 to be configured to generate a photometry in accordance with instructions received on a data bus internal to the motor vehicle, not shown. Alternatively, the control unit 130 can receive the image data II on such a data bus, for example of the CAN (“Car Area Network”) type. The control unit 130 preferably comprises calculation means configured to transform the image data II received for each pixel of the image into a supply voltage Vout and PWM signals intended for the pixelated light source 110 and the elementary light sources 112 respectively, so that a light beam in accordance with the data II is projected.

[0037] Although a high degree of brightness leads to greater heating of the corresponding elementary light sources, heating of the elementary light sources 112 cannot generally be predicted accurately solely on the basis of the data of the projected image II. This is due, among other things, to parasitic heating caused by neighboring light sources, to imperfections of the light sources due to their respective manufacturing processes, or to previous projections, which can generate residual heat at several elementary light sources.

[0038] Preferably, the pixelated light source 110 comprises a plurality of temperature sensors 121, 122, 123, 124 physically close to the semiconductor junctions. In the example of [fig.2] these are four sensors, without the invention being limited to this example. It may for example be a thermistor element or other temperature sensors per se known in the art, or advantageously PTAT (“Proportional To Asboute Temperature”) type sensors. The proximity to the matrix of the elementary light sources allows the sensors to provide a realistic indication of the operating temperature of pixel regions of the pixelated light source 110, when the latter is supplied with electricity.According to a preferred embodiment, a plurality of temperature sensors can be integrated into the substrate of the light source, and a plurality of temperature indications, corresponding to a plurality of areas or a plurality of pixels, can be provided via electrical signals T1, T2, T3, T4 to the control unit 130, thereby forming a temperature profile PT1 corresponding to the projection of the image data II.

[0039] The provided temperature profile PT1 does not allow access to the exact temperature values of all the elementary light sources. Thus, during step iii of the proposed method, a position of a hot spot is estimated by the unit of command. In the given example, a central area of the image data II is illuminated. Thus, the corresponding elementary light sources in the center of the pixelated light source 110 are likely to heat up the most during the projection of the image II. This area is far from all the temperature sensors 121, 122, 123, 124, whose positions are known. Similar or close indications T1, T2, T3, T4 are therefore likely in this example. Conversely, such a uniform temperature profile can make it possible to estimate that the hot spot is located in a central area of the matrix.

[0040] However, none of these values correspond to the exact temperature of the central zone. In order to estimate the temperature of the central zone, the control unit 130 can, for example, use a database comprising predetermined temperature profiles, associated with predetermined photometries II, 12, ..., IN, and with corresponding maximum temperatures. These data can, for example, be obtained beforehand by simulation, or by measurement using a thermal camera at the level of the elementary light sources while these project the corresponding photometries. By comparing the temperature profile PT1 with the profiles in the database, in particular in relation to the projected image II, the control unit can thus determine a temperature, or a temperature increment, which will have to be added to the values of the obtained temperature profile PT1, in order to have a realistic indication of the temperature in the central, illuminated zone.In the example provided, for the area furthest from the sensors 121, 122, 123, 124 which are located at the corners of the pixel matrix 110, the increment ATI may be of a value between 15 and 30°C, for example 25°C. The estimated temperature T is for example given by T2+ATI °.

[0041] The values of the increments or temperature values recorded in the database, which depend on the positions of determined hot spots, can optionally be adapted according to the operating time of the temperature sensors, to take into account measurement errors due to a variation in the sensitivity of the sensors, which generally deteriorates over the operating time.

[0042] The increment depends at least on the estimated position of the hot spot, the known position of the temperature sensors, and the projected image. [Fig. 3] gives another example. The projected photometry 12 comprises a first illuminated zone Z1 and a more restricted central zone Z2 highlighted. The four central elementary light sources 112 present a risk of pronounced overheating. However, because of the significant distance of the sensors 121, 122, 123, 124 from this central zone, and for lack of sensitivity, the temperature values T1, T2, T3, T4 are very similar to those of the previous example. To determine the temperature of the central zone, it is therefore interesting to compare the image data of zone Z2 with those of area Zl. Knowing that image 12 is projected, and not image II, the image data allows the control unit 130 to remove the ambiguity induced by the temperature profile obtained alone, and to determine that an increment AT2 larger than ATI is to be added to the temperatures obtained by the sensors, in order to provide a realistic estimate of the hottest temperature of the pixelated light source 110. Using only temperature values, the hot spot of this example cannot be discerned from the hot spot of the example of [fig. 3], while the four central pixels can undergo significantly higher heating, and therefore present a risk of more pronounced thermal runaway. The more precise estimate allows the control unit 130 to react differently, in a more nuanced manner, in the two projection examples II, 12 shown.

[0043] Another example is illustrated by [fig.4]. The photometry 13 which is projected includes an illuminated area in the top left. In this example, the temperature value T1 will be significantly higher than the temperatures T2, T3, T4. Thus the temperature profile provided by the sensors will allow by itself to evaluate the position of the hot spot in the area in direct proximity to the sensor 121: this is the top left quadrant of the pixel matrix 110. Taking into account the image data 13 optionally allows this position estimation to be refined. In the case shown, the temperature value T1 must be incremented by a small value, or even by a zero increment to arrive at a correct estimation of the hot spot. Indeed, the elementary light sources susceptible to overheating are close to one of the available temperature sensors.

[0044] Thus, after estimating the position of the hot spot of the pixelated light source 110, the control unit is configured to determine an estimate of the temperature value T of the hot spot, depending on the estimated position, and preferably depending on the projected image data II, 12, 13. The control unit 130 is further configured to determine, from the first supply voltage level provided, and from the estimated corresponding temperature T of the hot spot of the pixelated light source, whether there is a need to lower the intensity of the electric current in the pixelated light source, in order to avoid a thermal runaway situation.

[0045] For example, if the estimated temperature T of the hot spot exceeds a predetermined threshold value, the first voltage level is thus lowered to a second lower voltage level. This causes the maximum electric current intensity, or peak, which passes through the pixels 121 of the pixelated light source 110 to decrease, thus avoiding overheating of the corresponding semiconductor junctions.

[0046] According to a preferred embodiment of the invention, the control unit 130 comprises, or has write access to, a memory element 132 (illustrated in [fig.2]) in which reference data relating to the pixelated light source 110 are recorded. This data may, for example, be provided at the time of production or assembly of the light module.

[0047] [Fig. 5] shows a non-limiting example of reference data which can be used by the control unit in order to carry out step v of the control method in accordance with a preferred embodiment of the invention. This is data which characterizes the electro-thermal behavior of the pixels of the pixelated light source.

[0048] In the example shown, exceeding a threshold electrical current intensity set at 35mA risks causing permanent failure of the pixels of the pixelated light source. The control unit therefore ensures that this threshold is not exceeded for a prolonged period. The reference data provides, for an operating temperature range of, for example, -40°C to 150°C, curves associating the control voltage (in Volts) with the intensity of the resulting electrical current (in Amperes). It becomes apparent that the threshold temperature to which the temperature indication T is compared by the control unit, may depend on the value of the first electrical voltage, initially supplied to the pixelated light source, and which is at the origin of the estimated temperature T of the hot spot of the matrix. For example, at a voltage of 3.2 V, the maximum current intensity is reached at a temperature Te, as indicated by the intersection of the curve Te and the threshold current ceiling I. If the estimated temperature T of the hot spot obtained by the method is greater than Te while the first level of electrical driving voltage supplied is greater than 3.2 V, the control unit orders the supply of a second level of driving voltage, less than 3.2, to the control device. Conversely, at an initially supplied voltage of 3 V, the operating temperature Te of the hot spot can increase up to 150°C before a drop in the driving voltage is ordered by the control unit. The continuous application of this method makes it possible to regulate the temperature dynamically without risking a thermal runaway effect. The threshold value to which the estimated temperature indication T of the hot spot is compared therefore depends on the first level of electrical voltage supplied.The second electrical voltage level is chosen so that the maximum electrical current flowing through the pixels of the pixelated light source does not exceed a predetermined maximum threshold intensity, for example 35 mA.

[0049] In an alternative embodiment, the voltage level Vout can be maintained at the first level, and to reduce the average intensity of the electric currents which circulate in the elementary light sources, the PWM signals controlling these average current intensities can be adapted by reducing their ratio cyclic by a predetermined factor, preferably identical for all elementary light sources. A combination of voltage control adaptation and PWM signals can also be envisaged without departing from the scope of the present invention.

[0050] It goes without saying that the embodiments described do not limit the scope of protection of the invention. By using the description which has just been given, other embodiments are conceivable without departing from the scope of the present invention.

[0051] The scope of protection is determined by the claims.

Claims

Claims

1. Method for controlling a pixelated light source (110) for a motor vehicle, the pixelated light source being intended to be voltage-driven and comprising a plurality of elementary light sources (112) with an electroluminescent semiconductor element, the method comprising at least the steps of: i. controlling, by means of a control unit (130), the pixelated light source so as to project a light beam corresponding to image data (II, 12, 13), by providing it with a first level of electrical voltage (Vout), and by controlling each elementary light source by a pulse width modulation (PWM) signal of the direct current which determines a first average intensity of the electrical current passing through it; ii. obtaining, by means of a plurality of temperature sensors (121, 122, 123, 124) arranged at predetermined locations, a temperature profile (PT1) of the pixelated light source; iii. estimating, by means of the control unit, the position of a hot spot of the pixelated light source on the basis of the image data (II) and the obtained temperature profile (PT1); iv. estimating, by means of the control unit, a temperature value of said hot spot based on the temperature profile obtained and its estimated position relative to the locations of the temperature sensors; v. modify, by means of the control unit (130), the control (Vout, PWM) of the pixelated light source (110) so that each of the elementary light sources (112) is crossed by an electric current of a second average intensity, lower than the first intensity, if the estimated temperature value is higher than a predetermined threshold temperature value.

2. Control method according to the preceding claim, characterized in that the step of estimating the position of a hot spot iii comprises searching for the obtained temperature profile (PT1) among a plurality of temperature profiles pre-recorded in a memory element, each profile being associated with particular image data (II, 12, 13) and with a hot spot position associated with this data.

3. Control method according to one of the preceding claims, characterized in that the step of estimating a temperature value of said hot spot iv comprises a step of incrementing at least one of the temperature values (T1, T2, T3, T3) of the obtained temperature profile (PT1), using a predetermined increment which depends on the estimated position of the hot spot.

4. Control method according to the preceding claim, characterized in that the step of estimating a temperature value iv further comprises taking into account the projected image data (II, 12, 13), a high brightness value of a pixel corresponding to a hot elementary light source (112).

5. Control method according to one of the preceding claims, characterized in that the step of modifying the command v comprises a step of supplying a second electrical voltage level, lower than the first electrical voltage level (Vout), to the pixelated light source (110) if the estimated temperature value is greater than a predetermined threshold temperature value.

6. Control method according to the preceding claim, characterized in that the step of modifying the command v comprises a prior step of comparing said estimated temperature value with said predetermined threshold temperature value, the predetermined threshold temperature value being dependent on the first level of electrical voltage supplied.

7. Control method according to one of the two preceding claims, characterized in that it comprises a preliminary step of providing, in a memory element (132), reference data relating to the pixelated light source (110), which relate, for a row of operating temperatures of the pixelated light source, control voltage values with corresponding supply current intensities, and in that the step of modifying the control comprises the choice of the second electrical voltage level depending on the estimated temperature value, in order to respect a predetermined threshold electrical current intensity.

8. Control method according to one of the preceding claims, ca- characterized in that the step of modifying the control comprises a step of controlling each elementary light source (112) by a pulse width modulation (PWM) signal of the direct current which determines a second average intensity of the electric current which passes through it, the second average intensity being lower than the first average intensity, if the estimated temperature is higher than a predetermined threshold temperature value.

9. A light assembly (100) for a motor vehicle, comprising a pixelated light source (110) having a plurality of elementary light sources with an electroluminescent semiconductor element (112), the pixelated light source being intended to be voltage-controlled, a plurality of temperature sensors (121, 122, 123, 124) intended to provide a temperature profile (PT1, T1, T2, T3, T4) of the pixelated light source when it projects image data (II, 12, 13), and a control unit (130), characterized in that the control unit is configured to control the pixelated light source in dependence on an estimated temperature value of a hot spot of the pixelated light source, which depends on an estimated position of the hot spot and the image data.

10. Lighting assembly according to the preceding claim, characterized in that the control unit (130) is configured to carry out the steps according to any one of claims 1 to 8.

11. Lighting assembly according to one of claims 9 or 10, characterized in that the assembly comprises a memory element functionally connected to the control unit and comprising pre-recorded reference data relating to the pixelated light source.

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