Method for operating an automobile lighting device and automobile lighting device

Abstract

The invention provides a method of operating an automotive lighting device, the method including the steps of providing a first preliminary current profile, calculating a first preliminary derating time associated with the first preliminary current profile, providing a second preliminary current profile, calculating a second preliminary derating time associated with the second preliminary current profile, supplying the first current profile to a first light module, the first current profile providing a total amount of current less than the first preliminary current amount, and supplying the second current profile to a second light module, the second current profile providing a total amount of current greater than the second preliminary current amount.

Description

[Technical Field]

[0001] The present invention relates to the field of automotive lighting devices, and more particularly to the temperature control of the light sources contained in these devices. Summary of the Invention

[0002] Digital lighting devices are increasingly being adopted by automobile manufacturers in mid- and high-market products.

[0003] These digital lighting devices typically include solid-state light sources, the operation of which is highly temperature dependent.

[0004] Temperature control in these devices is a very delicate aspect and is usually achieved by derating, which means reducing the current flowing through the light source, with a corresponding reduction in output flux and operating temperature. This means that the performance of the light source needs to be significantly oversized to address these overheating issues, which can result in reduced operating values ​​while maintaining acceptable values.

[0005] Maintaining optimal performance within a headlamp, regardless of driving conditions, is extremely challenging. Frequently, one lighting module heats up faster than the others, thereby penalizing the remaining lighting modules due to the greater internal temperature of its HL. This phenomenon is not optimal because, when a lighting module derates, the remaining modules are also affected in order to ensure acceptable homogeneity, even though they have not yet reached the derating threshold.

[0006] This problem has been anticipated, but a solution is provided.

[0007] The invention provides an alternative solution for managing the temperature of the light source of a motor vehicle lighting device by means of a method for operating a motor vehicle lighting device according to the invention. Preferred embodiments of the invention are defined in the dependent claims.

[0008] Unless otherwise specified, all terms (including technical and scientific terms) used herein are to be interpreted as being conventional in the art. Furthermore, terms in common usage, unless expressly defined as such herein, should be interpreted as being conventional in the relevant art, and not in an idealized or overly formal sense.

[0009] In this text, the term "comprises" and its derivatives (such as "comprising") should not be understood in an exclusive sense, i.e., these terms should not be interpreted as excluding the possibility that what is described and defined may include further elements, steps, etc.

[0010] In a first aspect, the invention provides a method of operating an automotive lighting system comprising at least a first light module and a second light module, each of the light modules including a solid-state light source, the method comprising: - providing a first preliminary current profile to power the first light module such that the first light module generates a luminous flux greater than a first flux threshold; - calculating a first preliminary derating time associated with the first preliminary current profile, the first preliminary current profile being accompanied by a first preliminary current amount until the first preliminary derating time; - providing a second preliminary current profile to power the second light module such that the second light module generates a luminous flux greater than a second flux threshold; - calculating a second preliminary derating time associated with a second preliminary current profile, the second preliminary derating time being longer than the first preliminary derating time, and the second preliminary current profile involving a second current magnitude until the second preliminary derating time; - providing a first current profile to the first optical module, the first current profile providing a total current amount less than a first preliminary current amount, calculated up to a first preliminary derating time; - providing a second current profile to the second optical module, the second current profile providing a total current amount greater than the second preliminary current amount, the total current amount being calculated up to a second preliminary derating time; Includes.

[0011] The term "solid state" refers to light emitted by solid-state electroluminescence, which uses semiconductors to convert electricity into light. Compared to incandescent lighting, solid-state lighting produces visible light with reduced heat generation and lower energy dissipation. The typically small mass of solid-state electronic lighting devices provides greater resistance to shock and vibration compared to glass tubes / bulbs and long, thin filament wires. They also eliminate filament evaporation, potentially increasing the lifespan of lighting devices. Some examples of these lighting types include semiconductor light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), or polymer light-emitting diodes (PLEDs) as the source of illumination, rather than electric filaments, plasmas, or gases.

[0012] The calculated second preliminary derating time being longer than the first preliminary derating time means that preliminary derating times are calculated for both optical modules, and the first optical module has a shorter derating time and the second optical module has a longer derating time.

[0013] In the state-of-the-art, the preliminary derating time of the first module would jeopardize the performance of the entire lighting device because it would cause the second lighting module to be derated even though the second module does not yet need it. However, in the method of the present invention, the derating time of the second light module is shorter than the second preliminary derating time, resulting in an increase in the derating time of the first light module. Thus, the global derating time is extended, maintaining flux homogeneity and achieving good performance over a longer period of time.

[0014] In some particular embodiments, the first current profile and the second current profile include starting at a first current value and increasing the current value if a predetermined condition is reached.

[0015] In this way, the first and second current profiles are optimized to provide the minimum current needed at each instant, with the ability to increase the current as needed.

[0016] In some particular embodiments, obtaining the first current value is performed by a machine learning algorithm that obtains information from vehicle sensors.

[0017] The machine learning algorithm obtains information from various sensors on the vehicle and is trained and tested in various situations to obtain the maximum derating time for undesirable optical modules.

[0018] This machine learning algorithm can be located in the cloud or embedded in the vehicle's control unit.

[0019] In some particular embodiments, the vehicle sensors include at least some of a temperature sensor, a vehicle speed sensor, a geopositioning sensor, and a radar or lidar sensor.

[0020] In some particular embodiments, the predetermined condition includes the measured luminous flux value being below a corresponding flux threshold.

[0021] The luminous flux value is an important parameter, although it is not the only one that provides information about the operation of a lighting device. Controlling the current value with the luminous flux ensures acceptable operation of the total lighting module.

[0022] In some specific embodiments, the method further includes obtaining a light source temperature, and the predetermined condition includes the light source temperature reaching a predetermined value.

[0023] A different but compatible way of controlling current is by temperature, which can provide an indirect indication of luminous flux.

[0024] In some particular embodiments, the predetermined condition includes the fact that a time limit has been reached.

[0025] Another way to control the current is by simply using a timer, which estimates the temperature over time. In these cases, the current is increased automatically without the need to measure any data. This can be done if the time pattern is firmly established.

[0026] In some particular embodiments, the step of increasing the current value comprises increasing the current value from a first value to a second value, the second value being greater than the first value but less than 1.1 times the first value, particularly less than 1.05 times the first value, particularly less than 1.03 times the first value.

[0027] In these examples, the current may be increased by small amounts, with the current value (and temperature) kept as small as possible within the range that provides acceptable performance.

[0028] In some particular embodiments, the method further comprises recording a sequence of increasing current values ​​for a predetermined condition.

[0029] This sequence is useful when using a time-based pattern to avoid continuous temperature measurements.

[0030] In some particular embodiments, the first light module is a low beam module and the second light module is a high beam module, which has some synergistic effects since the low beam module and the high beam module may be activated simultaneously.

[0031] In some particular embodiments, the method steps are applied to at least 10% of the light sources of the corresponding light module.

[0032] The incremental current can be applied to multiple light sources simultaneously, for example to all light sources providing a given function, so that power savings and uniform performance can be applied to a large number of devices.

[0033] In a second aspect of the invention, the invention provides an automotive lighting device, the automotive lighting device comprising: a first optical module including a plurality of solid-state light sources; a second optical module including a plurality of solid-state light sources; - a control element for carrying out the steps of the method according to the first aspect of the invention; Equipped with.

[0034] This lighting device provides the advantageous feature of efficiently managing the performance of the light source.

[0035] In some particular embodiments, the automotive lighting device further comprises a thermistor intended to measure the temperature of the solid-state light source. [Brief explanation of the drawings]

[0036] [Figure 1]FIG. 1 is an overall perspective view of an automotive lighting device according to the invention. [Figure 2] FIG. 2 shows a graphical diagram of the standard operation of two light modules of a lighting device when the method according to the invention is not applied. [Figure 3] FIG. 3 shows another graph for the same phenomenon, but applied only to the first optical module. [Figure 4] FIG. 4 shows the course of the flux-temperature curve of the first module as operation according to the method of the invention continues. [Figure 5] FIG. 5 illustrates this comparison for a second optical module. [Figure 6] FIG. 6 shows a new graphical scheme of the operation of two light modules of a lighting device when the method according to the invention is used. DETAILED DESCRIPTION OF THE INVENTION

[0037] In these drawings, the following reference numbers are used: 1. First optical module 2 Second optical module 3 LED 4 Control Elements 5 Thermistor 6 Temperature Threshold 10. Lighting equipment 11 First preliminary curve for the first module 11' Invention curve for the first module 12 First preliminary curve for the second module 12' Invention curve for the second module 21 First preliminary derating temperature for the first module 21' First invention of optical module derating time 22 Second preliminary derating temperature for the second module 22' Second Optical Module Invention Derating Time 31 Original curve of the first state-of-the-art method for optical modules 41. Curve of invention relating to first optical module 51 Original curves of the state-of-the-art method for the second optical module 61 Invention curve for second optical module 100 automobile vehicles The exemplary embodiments are described in sufficient detail to enable those skilled in the art to implement and practice the systems and processes described herein. It is important to understand that the embodiments may be provided in many alternative forms and should not be construed as limited to the examples set forth herein.

[0038] Accordingly, while the embodiments may be modified in various ways and may take various alternative forms, specific embodiments thereof are shown by way of example in the drawings and will be described in detail below. There is no intention to limit the invention to the particular forms disclosed. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the appended claims.

[0039] FIG. 1 shows an overall perspective view of an automotive lighting device according to the invention.

[0040] The lighting device 10 is mounted on an automobile vehicle 100, - a first light module 1 comprising a plurality of LEDs 3; - a second light module 2 comprising a plurality of LEDs 3; - control element 4; - a number of thermistors 5 intended to measure the temperature of different sections of the first and second optical modules; Equipped with.

[0041] Each optical module is a high-resolution module with a resolution greater than 2000 pixels, but there is no limitation on the technology used to manufacture the projection modules.

[0042] A first example of this matrix configuration includes a monolithic source. This monolithic source includes a matrix of monolithic electroluminescent elements arranged in several columns and several rows. In a monolithic matrix, the electroluminescent elements can be grown on a common substrate and electrically connected so that they can be selectively activated individually or by a subset of the electroluminescent elements. The substrate can be made primarily of semiconductor materials. The substrate can also include one or more other materials, such as non-semiconductors (metals and insulators). Each electroluminescent element or group can thus form a light pixel and thus emit light when electricity is supplied to that material or materials. Such a monolithic matrix configuration allows the selectively activatable pixels to be placed very close to each other, compared to conventional light-emitting diodes intended to be soldered to a printed circuit board. The monolithic matrix can include electroluminescent elements whose major dimension, the height of the electroluminescent elements measured perpendicular to the common substrate, is substantially equal to 1 micrometer.

[0043] The monolithic matrix is ​​connected to a control center to control the generation and / or projection of pixelated light beams by the matrix arrangement, which allows the control center to individually control the light emission of each pixel of the matrix arrangement.

[0044] Alternatively to the one presented above, the matrix configuration may also include a primary light source attached to a matrix of mirrors. The pixelated light source is thus formed by the assembly of at least one primary light source formed by at least one light-emitting diode and an array of optoelectronic elements, for example a matrix of micromirrors, also known as DMD, an abbreviation for "digital micromirror device", which directs the light rays from the primary light source towards the projection optics by reflection. If necessary, secondary optics can collect the light rays of the at least one light source and focus and direct them onto the surface of the micromirror array.

[0045] Each micromirror can be swung between two fixed positions: a first position where the light beam is reflected toward the projection optical element, and a second position where the light beam is reflected in a direction different from the projection optical element. The two fixed positions are oriented in the same way for all micromirrors and form a characteristic angle of the micromirror matrix defined by its specifications with respect to a reference plane supporting the micromirror matrix. Such an angle is generally less than 20° and may typically be about 12°. In this way, each micromirror that reflects a portion of the light beam incident on the micromirror matrix forms an elementary emitter of the pixelated light source. The activation and control of the change in mirror position to selectively activate this elementary emitter to emit or not emit an elementary light beam are controlled by an emitter roll center.

[0046] In various embodiments, the matrix arrangement may include a scanning laser system, where a laser source emits a laser beam towards a scanning element configured to probe the surface of the wavelength converter with the laser beam, and an image of the surface is captured by projection optics.

[0047] The scanning element may be scanned at a speed high enough so that the human eye does not detect any displacement of the projected image.

[0048] The synchronized control of the firing of the laser source and the scanning movement of the beam makes it possible to generate a matrix of elementary emitters that can be selectively activated on the surface of the wavelength conversion element. The scanning means can be a movable micromirror for scanning the surface of the wavelength conversion element by reflecting the laser beam. The micromirror mentioned as the scanning means is, for example, of the MEMS type related to "Micro-Electro-Mechanical Systems". However, the invention is not limited to such a scanning means, and other types of scanning means can be used, such as a series of mirrors arranged on a rotating element, the rotation of which causes the laser beam to scan the transmission surface.

[0049] In another variation, the light source may be complex and may include both at least one segment of a light element, such as a light emitting diode, and a surface portion of a monolithic light source.

[0050] With multiple light sources in close proximity to each other, thermal control is very important to ensure good performance and efficiency.

[0051] FIG. 2 shows a graphical scheme of the standard operation of two light modules of a lighting device when the method according to the invention is not applied.

[0052] According to this figure, the first optical module increases its temperature over time according to a first curve 11. When a first preliminary derating time 21 is reached, the first optical module reaches a maximum temperature threshold 6 and needs to be derated to avoid damage.

[0053] Similarly, the second light module, if installed alone, will increase its temperature over time according to the second curve 12. When the second preliminary derating time 22 is reached, the second light module will have reached the maximum temperature threshold 6 and will need to be derated to avoid damage. Indeed, since the second light module is installed together with the first light module, which has a lower derating time, the second light module will need to be derated with the first preliminary derating time, which occurs before the second preliminary derating time, in order to guarantee beam homogeneity and to respect the regulation that does not allow the use of a high beam module without activating a low beam module.

[0054] Figure 3 shows another graph of the same phenomenon, applied only to the first optical module. In this graph, the luminous flux is plotted against the temperature. As the temperature increases (which occurs over time), the optical module follows curve 31 until it reaches the temperature threshold 6 and is derated to a lower intensity, which results in a lower luminous flux and a lower temperature. However, it again reaches the temperature threshold, which results in a new derating.

[0055] The first curve 31 defines a first amount of preliminary current up to a first preliminary derating time, and the second curve 12 defines a second amount of preliminary current up to a second preliminary derating time.

[0056] FIG. 4 shows the course of the flux-temperature curve 41 of the first module when operating according to the method of the invention.

[0057] For the preliminary current profile 31 in FIG. 2 (and therefore only for the first optical module), a dashed line is used for a better comparison between both methods.

[0058] The first light module is supplied with a first current value that is lower than the corresponding first value of the first preliminary current profile of FIG. 2. This first current value is calculated by a machine learning algorithm that is trained to obtain information from vehicle sensors and provide a value that provides the longest possible derating time for the first light module. This lower current value results in a lower luminous flux. To compensate for this difference in luminous flux and provide better flux uniformity, the second light module is supplied with a first current value that is higher than the corresponding first value of the second preliminary current profile, as shown in FIG. 5.

[0059] The current increase in curve 41 is from a first value to a second value, the second value being slightly larger than the first value, typically 1.01 to 1.05 times the first value. The current increase is low, but sufficient to maintain sufficient luminous flux for a long period of time.

[0060] Since the first value of the second current profile is larger than expected, the sum of both fluxes will be compensated and an acceptable value will be obtained. Thus, if a low value of total luminous flux (understood as the sum of the luminous fluxes of both the first and second optical modules) is achieved, the current value will increase over time.

[0061] Since the total amount of current for the first optical module (measured up to the first preliminary derating time) is less than in FIG. 2, the derating time is longer than the first preliminary derating time, as shown in FIG.

[0062] Figure 5 shows this comparison for a second optical module, where curve 51 represents the state-of-the-art method and curve 61 represents the present invention. As previously shown, curve 61 represents a higher current value than in Figure 2, which leads to a higher total current flow.

[0063] FIG. 6 shows a new graphical scheme of the operation of two light modules of a lighting device when the method according to the invention is used.

[0064] Curves 11' and 12' show the new course of temperature over time. For the first module, it is slower than curve 11. For the second module, it is faster than curve 12.

[0065] As already shown, using a lower current value in the first optical module with a lower total current amount results in a derating time 21' that is longer than the first preliminary derating time. Conversely, using a higher current value in the second optical module with a higher total current amount results in a derating time 22' that is shorter than the second preliminary derating time. However, the luminous flux uniformity is maintained and the minimum derating time (first one) is extended.

Claims

1. 1. A method for operating an automotive lighting device (10) comprising at least a first light module (1) and a second light module (2), each of said light modules comprising a solid-state light source (3), comprising: - providing a first preliminary current profile (11) to power said first light module (1) so that said first light module (1) produces a luminous flux greater than a first flux threshold; - calculating a first preliminary derating time (21) associated with said first preliminary current profile (11), said first preliminary current profile (11) being accompanied by a first preliminary current amount until said first preliminary derating time (21); providing a second preliminary current profile (12) to power said second light module (2) so that said second light module produces a luminous flux greater than a second flux threshold; - calculating a second preliminary derating time (22) associated with said second preliminary current profile, said second preliminary derating time (22) being longer than said first preliminary derating time (21), said second preliminary current profile (12) being accompanied by a second preliminary current amount until said second preliminary derating time (22); - supplying said first optical module with a first current profile (11') that provides a total current amount that is less than said first preliminary current amount, calculated up to said first preliminary derating time (21); - supplying the second optical module (2) with a second current profile that provides a total current amount greater than the second preliminary current amount, calculated up to the second preliminary derating time (22); Including, The method, wherein the first current profile (11') and the second current profile include starting at a first current value and increasing the current value when a predetermined condition is reached.

2. The method of claim 1 , wherein obtaining the first current value is performed by a machine learning algorithm that obtains information from vehicle sensors.

3. The method of claim 2 , wherein the vehicle sensors include at least some of a temperature sensor, a vehicle speed sensor, a geopositioning sensor, and a radar or lidar sensor.

4. The method of claim 1 , further comprising obtaining a light source temperature, wherein the predetermined condition includes the light source temperature reaching a predetermined value.

5. 5. The method of claim 1, wherein the step of increasing the current value comprises increasing the current value from a first value to a second value, the second value being greater than the first value but less than 1.1 times the first value.

6. 6. The method of claim 5, wherein the step of increasing the current value comprises increasing the current value from a first value to a second value, the second value being less than 1.05 times the first value.

7. 7. The method of claim 6, wherein the step of increasing the current value comprises increasing the current value from a first value to a second value, the second value being less than 1.03 times the first value.

8. A method according to any one of the preceding claims, further comprising the step of recording the sequence of increases in current value in the first current profile (11') and in the second current profile for a predetermined condition.

9. The method according to any one of claims 1 to 8, wherein the first light module is a low beam module and the second light module is a high beam module.

10. a first light module (1) comprising a plurality of solid-state light sources (3); a second light module (2) comprising a plurality of solid-state light sources (3); a control element (4) for carrying out the steps of the method according to any one of claims 1 to 9; An automotive lighting device comprising:

11. 11. Automotive lighting device according to claim 10, further comprising a thermistor (5) intended to measure the temperature of the solid-state light source.

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