Method for operating a vehicle lighting device

Abstract

The invention provides a method for operating an automotive lighting device (1) comprising at least one solid state light source. The method comprises the steps of defining a color allowance condition (6), feeding the light source with a current value (41) which results in a luminous flux value above a minimum luminous flux threshold (4), measuring the temperature in the light source, checking whether the output color meets the allowance condition (6), and increasing or decreasing the current value, thereby always keeping the current at a value such that an acceptable color can be produced. The last step comprises performing pulse width modulation on the current value, to keep the average value of the current at a value which results in a luminous flux value above the minimum luminous flux threshold (4). The invention also provides an automotive lighting device (1) comprising a control element (3) for performing the steps of this method.

Description

[0001] This invention relates to the field of automotive lighting equipment, and more particularly to color management of light sources included in these devices.

[0002] Automakers are increasingly using digital lighting equipment in their mid-to-high-end products.

[0003] These digital lighting devices typically include solid-state light sources, whose operation is largely dependent on temperature.

[0004] Temperature control in these components is a highly sensitive aspect and is typically implemented through derating, which means reducing the current supplying the light source, consequently decreasing the output flux and lowering the operating temperature. This necessitates significantly overclocking the light source to address these overheating issues, ensuring that operating values ​​remain acceptable even when they can be reduced.

[0005] Furthermore, these techniques can also affect the color of the output pattern. This can cause the output color to not meet specifications in certain situations, especially within certain temperature ranges.

[0006] The problem is believed to have existed until now, and a solution has been provided.

[0007] This invention provides an alternative solution for managing the output color of a light source pattern through a method for operating an automotive lighting device and an automotive lighting device.

[0008] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall be interpreted in accordance with their customary usage in the field. It will be further understood that terms of common usage shall also be interpreted in accordance with their customary usage in the relevant field, and shall not be interpreted in an idealized or overly formal sense unless expressly specified herein.

[0009] In this document, the term “comprises” and its derivatives (such as “comprising”, etc.) should not be understood in an exclusive sense, that is, these terms should not be interpreted as excluding the possibility that the content described and defined may include other elements, steps, etc.

[0010] In a first aspect, the present invention provides a method for operating an automotive lighting device including at least one solid-state light source, the method comprising the following steps:

[0011] • Define color permissible conditions, wherein, for each temperature-current pair, the color is defined as acceptable or unacceptable;

[0012] • Establish minimum luminous flux threshold and maximum luminous flux threshold;

[0013] • The solid-state light source is fed with a current value that produces a luminous flux value between a minimum luminous flux threshold and a maximum luminous flux threshold.

[0014] • Measure or estimate the temperature in the light source;

[0015] • The color of the light emitted by the light source is obtained based on the measured or estimated temperature and the current fed to the solid-state light source;

[0016] • Check whether the obtained color meets the allowed conditions;

[0017] • If the obtained color does not meet the allowable condition, increase or decrease the current value to produce a color that meets the allowable condition;

[0018] • If the luminous flux value generated by increasing or decreasing the current value is lower than the minimum luminous flux threshold or higher than the maximum luminous flux threshold, then pulse width modulation is performed on the current value to generate a luminous flux value that falls between the minimum luminous flux threshold and the maximum luminous flux threshold.

[0019] The term "solid-state" refers to light emitted through 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 less energy dissipation. The typically smaller mass of solid-state electronic lighting devices provides greater shock and vibration resistance compared to fragile glass tubes / bulbs and long, thin filaments. Solid-state light sources also eliminate filament evaporation, potentially increasing the lifespan of the lighting device. 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 light source, rather than filaments, plasma, or gas.

[0020] Color permissible conditions are defined by datasheets and / or experimental data. For a given value of current and temperature, the output color of the light source can be obtained. The obtained color may or may not conform to the specifications, as the specifications also provide a range of acceptable and unacceptable colors. Therefore, consider whether a current-temperature pair satisfies the permissible conditions.

[0021] In this way, the light source can calculate whether the output color is permissible, and can react to disallowed situations by modifying the feed current, so that the color always remains within the permissible range.

[0022] When the luminous flux provided by the current level required to maintain color within permissible conditions exceeds the limits established by minimum and maximum luminous flux thresholds, this invention provides a solution to the problem by performing pulse width modulation on the current value to obtain different current average values, thereby producing different luminous flux. In fact, the luminous flux is directly derived from the average current value.

[0023] In some specific embodiments, the step of obtaining color is performed using data sheets and / or experimental data, which provide color based on temperature and current values.

[0024] There are many alternative methods to obtain the output color of a light source. Sometimes, the manufacturer's datasheet provides reliable and useful information about these parameters, but experimental data can also be used to obtain the permissible conditions.

[0025] In some specific embodiments, the method further includes the step of establishing a maximum luminous flux threshold, and the method includes maintaining the average current such that a luminous flux value below the maximum luminous flux threshold can be generated.

[0026] The maximum flux value can also be used to limit the luminous flux within a specified range.

[0027] In some specific embodiments, the step of measuring the temperature of the solid-state light source is performed by a thermistor (such as a negative temperature coefficient thermistor). In different embodiments, the temperature is estimated by other means, such as using data tables, recognition, or AI technologies.

[0028] Thermistors are common components that can be used to measure temperature, thus providing a reliable starting point for this method.

[0029] In some specific embodiments, the step of increasing the current value involves increasing the current value from its current value to an increased current value that is more than 1.2 times the current value.

[0030] In these examples, the intensity can increase over a high range, allowing for significant increases in current (and temperature). However, pulse width modulation helps mitigate the effects of this high increase.

[0031] In some specific embodiments, the step of increasing the current value involves increasing the current value to an increased current value that is the minimum possible value that produces a color that satisfies the permissible conditions.

[0032] Within an acceptable color range, this increased current value is kept as low as possible. Therefore, the effect of this increase is kept as minimal as possible and will be fixed through pulse width modulation.

[0033] In some specific embodiments, the step of increasing the current value further includes the step of maintaining the increased current value constant while performing pulse width modulation of more than one value.

[0034] Dynamic control over current and color is achieved through pulse width modulation, rather than by further altering the current value.

[0035] In some specific embodiments, the method further includes the step of recording a sequence of current value increments for each predetermined temperature condition, wherein the increased or decreased current value is based on the recorded sequence of current value increments depending on the measured or estimated temperature.

[0036] When using a time-based model, this sequence can be used to avoid continuous temperature measurements.

[0037] In some specific embodiments, the steps of the method are applied to at least 10% of the solid-state light source of the lighting device.

[0038] The current value can be gradually increased simultaneously and applied to a large number of light sources, such as all light sources providing a predetermined function. Therefore, this energy-saving and uniform performance can be applied to a large number of components.

[0039] In some embodiments, the automotive lighting device includes at least two solid-state light modules, a first solid-state light module including a first solid-state light source, and a second solid-state light module including a second solid-state light source. The method further includes:

[0040] • Define a uniformity standard, for which the color pairs emitted by the first optical module and the second optical module are defined as acceptable or unacceptable.

[0041] • The first optical module is fed with a first current value, which generates a luminous flux value between a minimum luminous flux threshold and a maximum luminous flux threshold.

[0042] • The second optical module is fed with a second current value, which generates a luminous flux value between a minimum luminous flux threshold and a maximum luminous flux threshold.

[0043] • Measure or estimate the temperature in the first optical module and the second optical module;

[0044] • The color of the light emitted by the first optical module is obtained based on the measured or estimated temperature and the first current value in the first optical module, and the color of the light emitted by the second optical module is obtained based on the measured or estimated temperature and the second current value in the second optical module.

[0045] • Check whether the color of the light emitted by the first optical module meets the allowable condition, whether the color of the light emitted by the second optical module meets the allowable condition, and whether the color pair emitted by the first optical module and the second optical module meets the uniformity standard;

[0046] • If the color of the light emitted by the first optical module does not meet the allowable condition, if the color of the light emitted by the second optical module does not meet the allowable condition, or if the color pair emitted by the first optical module and the second optical module does not meet the uniformity standard, then increase or decrease the first current value and / or the second current value so that the light generated by the first optical module and the second optical module meets the allowable condition and the uniformity standard;

[0047] • If the luminous flux value generated by increasing or decreasing the first current value or the second current value is lower than the minimum luminous flux threshold or higher than the maximum luminous flux threshold, then pulse width modulation is performed on the first current value or the second current value to generate a luminous flux value that is between the minimum luminous flux threshold and the maximum luminous flux threshold.

[0048] The uniformity criterion is defined as the similarity between output color pairs. For example, it can be defined in terms of RGB range or distance in a color diagram (e.g., the chromaticity diagram of the CIE color space), but any definition by those skilled in the art is part of the scope of this invention.

[0049] Using this method, lighting equipment can calculate whether the output color conforms to both uniformity standards and permissible conditions, and whether the luminous flux value is between the minimum luminous flux threshold and the maximum luminous flux threshold.

[0050] In practice, lighting equipment can include several solid-state light modules, which affect the output pattern of the light equipment. When the solid-state light modules have different temperatures, the color throughout the pattern may be uneven. Limitations on uniformity standards can overcome this problem.

[0051] Based on this method, active control is performed on the current values ​​of the two optical modules, thereby allowing different current strategies to be adopted for each solid-state optical module depending on the temperature evolution registered for each solid-state optical module.

[0052] As a supplement, the increased current value of the first optical module and / or the second optical module is calculated using color and temperature as input values, based on data sheets and / or experimental data.

[0053] There are many alternative methods to obtain the output color of a solid-state light source. Sometimes, the manufacturer's datasheet provides reliable and useful information about these parameters, but experimental data can also be used to obtain the permissible conditions.

[0054] According to the embodiment, the first current value is increased, and the increased first current value is calculated based on data obtained from the first solid-state optical module, while the second current value is calculated based on the color and uniformity standards output by the first solid-state optical module.

[0055] In this case, the first solid-state optical module dominates the method, and the second solid-state optical module has a follow-up configuration to ensure the color uniformity of the output pattern of the optical device.

[0056] As an addition, the step of increasing or decreasing the first current value or the second current value includes first defining the increased or decreased current value for the optical module with a higher temperature, and then defining the increased or decreased current value for the optical module with a lower temperature.

[0057] Therefore, modules with higher temperatures can increase or decrease their current values, and modules can increase or decrease their current values ​​to meet uniformity criteria. Each optical module can follow its own strategy, which can differ in action (increase or decrease) and / or timing (one current value can remain constant while another increases or decreases).

[0058] In some embodiments, the determination of which module should increase or decrease its current value is provided by the LED driver of the entire lighting device, such that the determination is coordinated and avoids any conflict.

[0059] According to some embodiments, the method further includes the step of recording a sequence of current value increments for each predetermined temperature condition, wherein the increased or decreased first or second current value is based on the recorded sequence of current value increments depending on the measured or estimated temperature in the first and second optical modules.

[0060] When using a time-based model, this sequence can be used to avoid continuous temperature measurements.

[0061] According to some embodiments, at least some steps of the method are performed by a control unit configured to estimate the timing pattern of providing a first current value and a second current value to the first optical module and the second optical module in the following manner:

[0062] • The control unit is trained using a training dataset to estimate the current values ​​of the first optical module and / or the second optical module; and

[0063] • Test the control unit using actual current values.

[0064] The control unit can employ an artificial intelligence strategy to predict the optimal evolution of the first and second currents. To this end, the control unit is trained using a training dataset that can include various inputs: currents from other modules, external conditions, vehicle speed, driver decisions, etc. Using these values, the control unit is trained to predict the optimal evolution of the first and second current values.

[0065] In a second aspect of the invention, the present invention provides a computer program including instructions that, when executed by a control unit, cause the control unit to perform the steps of the method according to any one of claims 1 to 14.

[0066] In a third aspect of the invention, the present invention provides an automotive lighting device comprising:

[0067] • Matrix arrangement of solid-state light sources;

[0068] • A control element for performing the steps of the method according to the first aspect of the invention.

[0069] This lighting equipment offers the advantage of efficiently managing the color performance of the light source.

[0070] In some embodiments, the automotive lighting device includes at least two second solid-state light modules, the first solid-state light module including a first solid-state light source, and the second solid-state light module including a second solid-state light source, wherein the control element is configured to perform steps of a method according to some embodiments of the first aspect of the invention.

[0071] In some specific embodiments, the matrix arrangement includes at least 2,000 solid-state light sources.

[0072] A matrix arrangement is a typical example of this method. Rows can be grouped by projection distance range, with each column in each group representing an angular interval. This angular value depends on the resolution of the matrix arrangement, which typically includes between 0.01º and 0.5º per column. As a result, many light sources can be managed simultaneously.

[0073] [ Figure 1 A perspective view of an automotive lighting device according to the present invention is shown.

[0074] [ Figure 2 The diagram shows a graph representing the luminous flux produced by a solid-state light source when fed by a specific current value and at a specific temperature, according to a first embodiment of the present invention.

[0075] [ Figure 3 An example of current evolution in a solid-state light source is shown in the method according to a first embodiment of the present invention.

[0076] [ Figure 4 A diagram is shown according to a second embodiment of the present invention.

[0077] [ Figure 5 This shows a color graphic representation.

[0078] [ Figure 6 The graph shows the luminous flux produced by a solid-state source of one of the optical modules when fed by a specific current value and at a specific temperature.

[0079] [ Figure 7 An example of the evolution of current over time in the first and second optical modules according to a second embodiment of the present invention is shown.

[0080] The following reference numerals have been used in these figures:

[0081] 1. Lighting equipment

[0082] 2 optical modules

[0083] 3 Control Components

[0084] 4a Minimum luminous flux threshold

[0085] 41A current value

[0086] 42A Increase / Decrease Current Value

[0087] 5. Thermistor

[0088] 6a Dot not allowed

[0089] 7a Maximum luminous flux threshold

[0090] 100 motor vehicles

[0091] The exemplary embodiments are described in sufficient detail to enable those skilled in the art to implement and carry out the systems and processes described herein. It is important to understand that embodiments may be provided in many alternative forms and should not be construed as limited to the examples set forth herein.

[0092] Therefore, although the embodiments may be modified in various ways and take various alternative forms, specific embodiments thereof are shown in the accompanying drawings and are described in detail below as examples. There is no intention to limit oneself to the specific forms disclosed. Rather, all modifications, equivalents, and alternatives falling within the scope of the appended claims should be included.

[0093] [ Figure 1 A perspective view of an automotive lighting device according to the present invention is shown.

[0094] This lighting device 1 is installed in the motor vehicle 100 and includes

[0095] • A matrix arrangement forming at least one solid-state light source, the matrix arrangement being designed to provide a light pattern. For example [ Figure 1 As shown, the matrix arrangement may include two optical modules 2 designed to provide a light pattern. Each optical module may include a solid-state light source;

[0096] • Control element 3 for thermal control of LED 2 operation; and

[0097] • A thermistor 5 is designed to measure the temperature in an LED. The thermistor can also be used to measure the temperature in an optical module 2.

[0098] This matrix configuration is a high-resolution module with a resolution greater than 2000 pixels. However, there are no restrictions on the technology used to produce the projection module.

[0099] A first example of this matrix configuration includes a monolithic source. This monolithic source comprises a matrix of monolithic electroluminescent elements arranged in columns and rows. In the monolithic matrix, the electroluminescent elements can be grown from a common substrate and electrically connected to selectively activate individually or as a subset of the electroluminescent elements. The substrate can be made primarily of semiconductor material. The substrate can include one or more other materials, such as non-semiconductors (metals and insulators). Thus, each electroluminescent element / group can form a light pixel and therefore emit light when its / their material is powered. This monolithic matrix configuration allows selectively activated pixels to be arranged very close to each other, compared to conventional light-emitting diodes designed to be soldered onto a printed circuit board. The monolithic matrix can include electroluminescent elements whose main height dimension, measured perpendicular to the common substrate, is substantially equal to one micrometer.

[0100] A monolithic matrix is ​​coupled to a control center to control the generation and / or projection of pixelated beams by the matrix arrangement. The control center can therefore individually control the light emission of each pixel in the matrix arrangement. The control center is also known as an LED driver.

[0101] As an alternative to the above-presented solution, the matrix arrangement may include a main light source coupled to the mirror matrix. Thus, the pixelated light source is formed by an assembly of at least one main light source and an array of photoelectric elements, the at least one main light source being formed by at least one light-emitting diode emitting light, the photoelectric element array being, for example, a matrix of micromirrors, also known as a DMD (an acronym for "Digital Micro-mirror Device"), which guides the light from the future autonomous light source to the projection optics by reflecting it. Where appropriate, auxiliary optics may collect the light from at least one light source to focus and guide it onto the surface of the micromirror array.

[0102] Each micromirror can pivot between two fixed positions: a first position and a second position. In the first position, light is reflected toward the projection optics; in the second position, light is reflected in a different direction than the projection optics. The two fixed positions are oriented in the same manner for all micromirrors and form a characteristic angle of the micromirror matrix relative to the reference plane supporting the matrix, defined by its specifications. This angle is typically less than 20° and can generally be about 12°. Thus, each micromirror, reflecting a portion of the light beam incident on the micromirror matrix, forms the basic emitter of the pixelated light source. The actuation and control of the mirror position changes for selectively activating this basic emitter to emit or not emit the basic beam are controlled by a control center.

[0103] In various embodiments, the matrix arrangement may include a scanning laser system in which a laser source emits a laser beam toward a scanning element configured to probe a surface of a wavelength converter with the laser beam. An image of this surface is captured by projection optics.

[0104] The scanning element can be detected at a speed high enough that the human eye cannot perceive any displacement in the projected image.

[0105] Synchronous control of the illumination of the laser source and the scanning motion of the beam allows for the generation of a matrix of basic emitters, which can be selectively activated at the surface of the wavelength converter element. The scanning device can be a movable micromirror used to scan the surface of the wavelength converter element by reflection of the laser beam. The micromirror mentioned as a scanning device is, for example, of the MEMS (“Micro-Electro-Mechanical Systems”) type. However, the invention is not limited to this type of scanning device, and other types of scanning devices can be used, such as a series of mirrors arranged on a rotating element, the rotation of which causes the transmission surface to be scanned by the laser beam.

[0106] In another variant, the light source can be composite and includes at least one segment of an optical element (such as a light-emitting diode) and a surface portion of a monolithic light source.

[0107] Figure 2 and Figure 3 A first embodiment in which the invention is applied to a matrix arrangement in a solid-state optical module 2 is described, while Figure 4 , Figure 5 , Figure 6 , Figure 7 Figure 8 illustrates a second embodiment in which the invention is applied to an optical device having two solid-state optical modules 2.

[0108] [ Figure 2The graph shows the luminous flux produced by a solid-state light source when fed by a specific current value and at a specific temperature. Furthermore, some disallowed points, point 6a, have been added to this graph. Point 6a represents a combination of current values ​​and temperatures that would provide colors unacceptable to some automotive regulations.

[0109] The figure also shows the minimum luminous flux threshold 4a and the maximum luminous flux threshold 7a.

[0110] In this particular embodiment of the method according to the invention, the operation of the light source is controlled under certain conditions.

[0111] The first prerequisite is that the luminous flux should be kept between the minimum luminous flux threshold of 4a and the maximum luminous flux threshold of 7a.

[0112] The second prerequisite is that the output color should meet the allowed conditions, that is, it should not be at point 6a, which is not allowed as shown in the figure.

[0113] This performance is controlled by the current supplied to the solid-state light source. Changes in the current cause changes in luminous flux and output color.

[0114] Therefore, in order to provide acceptable performance in terms of color and luminous flux, smaller variations should be used.

[0115] [ Figure 3 An example of the evolution of current values ​​in a solid-state light source in a method according to a first embodiment of the present invention is shown.

[0116] First, when the temperature in the LED is still low, a current value of 41a is chosen, which is closer to the maximum threshold of 7a than the minimum threshold of 4a. This current value of 41a, paired with this temperature, provides a permissible output color, which is far from the disallowed point of 6a shown in the figure.

[0117] Over time, the temperature rises, and the luminous flux provided by the initial current value 41a, while still within the permissible range, will be lower than the initial luminous flux. The temperature rises until a region is reached where no available current value can provide a permissible color (all current value lines have a disallowable point 6a). The only way to obtain a permissible color is to increase the current value to an increased current value 42a, which is greater than 1.2 times the initial current value 41a, exceeding the maximum luminous flux threshold 7a.

[0118] However, this increased current value can cause the light source to emit more luminous flux than specified. This is compensated for by applying pulse width modulation (PWM) to the current supplied to the light source. At the initial current value, the PWM value is 90%, but as the current increases to this increased value, the PWM value is modified to 48% to keep the average current value within the allowable range, thus preventing color distortion.

[0119] When the temperature rises and the luminous flux should be increased to compensate for the increased temperature, the current value remains constant and the pulse width modulation value is gradually modified from 48% to 56%, 62% and 88% to achieve dynamic control of luminous flux, color and temperature.

[0120] [ Figure 4 The diagram shown is based on a second embodiment of the invention, in which the light pattern is described as consisting of projections from two different light modules 2 (referred to as the first light module and the second light module).

[0121] In this example corresponding to the low beam pattern, the complete projection 11 can be divided into a first part 12 and a second part 13. In this particular pattern, the first part 12 is generally referred to as the "flat" part, and the second part 13 is generally referred to as the "bent" part. The first part 12, or the "flat" part, presents a low beam pattern with a flat cutoff line. The second part 13, or the "bent" part, has the characteristic bend of the low beam. The first optical module is responsible for projecting the "flat" part 12, and the second optical module is responsible for projecting the bent part "13".

[0122] Since the two parts 12 and 13 are designed to form a unique pattern 11, it is important that the output colors of these light modules be as similar as possible.

[0123] Uniformity standards are defined by the manufacturer, for example, in terms of the range in RGB mode or in terms of color (e.g., [...]). Figure 5 The distance shown in the figure is used to define the distance.

[0124] [ Figure 5 The image shows a color graphical representation, which is a chromaticity diagram of the CIE color space, where the uniformity criterion is that the output color pairs are contained within the "white area" 14. This is an example of a standard, but a technician can create any similar standard.

[0125] For example, another uniformity criterion could be that the distance between the colors in the output color pair in the color graphic representation is less than a predefined distance.

[0126] [ Figure 6 The graph shows the luminous flux produced by a solid-state source of one of the optical modules 2 when fed by a specific current value and at a specific temperature. Further, some disallowed points 6b have been added to this graph. Point 6b represents a combination of current values ​​and temperatures that would provide a color that does not meet the permitted conditions.

[0127] The figure also shows the minimum luminous flux threshold 4b and the maximum luminous flux threshold 7b.

[0128] In a second embodiment of the method according to the present invention, the operation of the solid-state light source of the two optical modules 2 is controlled under certain conditions.

[0129] The first prerequisite is that the luminous flux should be kept between the minimum luminous flux threshold of 4b and the maximum luminous flux threshold of 7b.

[0130] The second prerequisite is that the output colors of the first optical module and the second optical module meet the allowed conditions, that is, they are not at the disallowed point 6a shown in the figure.

[0131] The third prerequisite is that the color pairs output by the first and second optical modules meet the uniformity standard.

[0132] This performance is controlled by the current supplied to the first solid-state light source of the first optical module and the second solid-state light source of the second optical module. Changes in the current cause changes in luminous flux and output color.

[0133] Therefore, in order to provide acceptable performance in terms of color and luminous flux, smaller variations should be used.

[0134] Several options can be used to achieve this goal.

[0135] In the first option, to include [ Figure 6 The first optical module is fed with a current value between the threshold values ​​4b and 7b. Then, the first color output by the first module is determined using theoretical and experimental data, and a second current value is selected to feed the second module to obtain the same color as the first output color, or at least meet the uniformity standard.

[0136] In the second option, from [ Figure 5 The diagram shows the selection of colors for both the first and second modules. Using theoretical and experimental data for each optical module, a first current value and a second current value are obtained to provide a first and second output color that are similar to the selected color and meet uniformity standards.

[0137] However, in some cases, to avoid disallowing point 6b or for any other reason, at least one of the current values ​​needs to be increased to above the maximum luminous flux threshold 7b or decreased to below the minimum luminous flux threshold 4b. Such cases include […]. Figure 7 As shown in the image.

[0138] [ Figure 7The illustration shows an example of the evolution of current over time in the first optical module and the second optical module 2 according to a second embodiment of the present invention. A first current value 41b, between a threshold value 4b and 7b, is selected to power the first optical module 2. Then, when the control unit determines that there is a reason to increase the current (to avoid the occurrence of an unacceptable point 6b when the temperature rises or for any other reason), the first current value is increased to an increased first current value such that the first color output by the first module meets the permissible condition. However, the first current value can also be decreased to a decreased first current value such that the first color output by the second module meets the permissible condition.

[0139] The control unit can be designed to determine which option is better, increasing or decreasing the first current value (unless one of these options is adopted as provided by the car manufacturer) and how these current values ​​should be managed.

[0140] In the second embodiment, the control unit can compare only the temperatures of the first optical module and the second optical module 2, and provide a more flexible scenario for the optical module with the higher temperature.

[0141] Therefore, data provided by external sensors can be used to train the control unit in an artificial intelligence algorithm.

[0142] In the first process, the control unit is trained. For this purpose, each optical module is provided with […]. Figure 6 The diagram shown is for clearly establishing the boundary conditions.

[0143] Then, data is provided from external sensors, including module temperature, module current value, external temperature, vehicle speed, driver settings, etc. The control unit uses this data to obtain the optimal first and second current values ​​at each moment, and tests these results using values ​​provided by the manufacturer. Once this training-testing process is complete, the control unit is ready to be installed in the automotive lighting system and control the current values ​​of the two light modules.

[0144] Return to [ Figure 7 The evolution of the process involves feeding the first module with a first current value 41b and the second module with a second current value 43b. The temperatures of the first and second optical modules are measured or estimated. Based on these temperatures and current values, the following is determined:

[0145] • Does the first color output by the first module meet the allowed conditions?

[0146] • Does the second color output by the second module meet the allowed conditions?

[0147] • Whether the first and second color pairs meet the uniformity standard.

[0148] exist[ Figure 7 In the example shown in the solid line, due to the temperature increase in the first module, the first current value of the first optical module increases from a first value 41b to an increased first value 42b, which is more than 1.2 times the first value to meet the allowable conditions. This significant increase is due to the fact that for some temperatures reached by the first module 2, the unacceptable region covers the entire range between the flux thresholds 4b and 7b. Since the luminous flux caused by this high current value is higher than the maximum luminous flux threshold 7b, pulse width modulation is performed on the increased first current supplied to the first optical module so that the luminous flux of the first optical module 2 is within the thresholds 4b and 7b. In this example, the PWM value is set to 56%.

[0149] The second current value 43b fed to the second optical module follows a different pattern shown by the dashed lines. Once the first current value increases to the increased current value 42b, the second current value 43b also needs to increase to ensure that the first and second colors meet the uniformity standard. Therefore, the second optical module 2 also receives the increased current value, but due to the lower temperature of this second optical module, the current value is increased to a higher increased second current value 43b than the increased first current value to meet the uniformity standard. The increased second current value 43b is also outside the thresholds 4b and 7b. As a result, pulse width modulation is also performed on the second current value supplied to the second optical module 2 so that the luminous flux is within the thresholds 4b and 7b. In this example, the PWM value of the increased second current value 43b is set to 48%.

[0150] The future evolution of the first and second current values ​​is different, and the second optical module will make concessions accordingly, so that the modification of the first current value of the first optical module with higher temperature can be more flexible, thereby better controlling the temperature while meeting the uniformity, color tolerance and flux threshold standards.

Claims

1. A method for operating an automotive lighting device (1), the automotive lighting device comprising at least one solid-state light source, the method comprising the steps of: • Define the permissible conditions for color (6), wherein, for each temperature-current pair, the color is defined as acceptable or unacceptable; • Establish minimum luminous flux thresholds (4a; 4b) and maximum luminous flux thresholds (7a; 7b); • The solid-state light source is fed with a current value (41a; 41b) that produces a luminous flux value between the minimum luminous flux threshold (4a; 4b) and the maximum luminous flux threshold (7a; 7b); • Measure or estimate the temperature in the solid-state light source; • The color of the light emitted by the solid-state light source is obtained based on the measured or estimated temperature and the current value fed to the solid-state light source; • Check whether the obtained color meets the permitted conditions (6); • If the obtained color does not meet the allowed conditions, increase or decrease the current value to produce a color that meets the allowed conditions; • If the luminous flux value generated by increasing or decreasing the current value (42a; 42b) is lower than the minimum luminous flux threshold (4a; 4b) or higher than the maximum luminous flux threshold (7a; 7b), then pulse width modulation is performed on the current value to generate a luminous flux value that falls between the minimum luminous flux threshold (4a; 4b) and the maximum luminous flux threshold (7a; 7b).

2. The method according to claim 1, wherein, The step of obtaining the color is performed using data tables and / or experimental data, which provide the color based on the temperature and the current value.

3. The method according to claim 1, wherein, The step of increasing the current value involves increasing the current value to an increased current value (42a; 42b) that is 1.2 times higher than the current value (41a; 41b).

4. The method according to claim 1, wherein, The step of increasing the current value involves increasing the current value (41) to the minimum possible increased current value (42) that produces a color that satisfies the permitted conditions.

5. The method according to claim 4, wherein, The step of increasing the current value further includes the step of keeping the increased current value (42a; 42b) constant while performing pulse width modulation of more than one value.

6. The method according to any one of claims 1 to 5, further comprising the step of recording a sequence of incremental current values ​​for each predetermined temperature condition, wherein, The increased or decreased current values ​​(42a; 42b) are based on a sequence of recorded current value increments that depend on the measured or estimated temperature.

7. The method according to any one of claims 1 to 5, wherein, The steps of the method are applied to at least 10% of the light source of the lighting device.

8. The method according to any one of claims 1 to 5, wherein, The automotive lighting device includes at least two optical modules (2), wherein the first optical module includes a first solid-state light source, and the second optical module includes a second solid-state light source, wherein the method further includes: • Define a uniformity standard (14), for which the color pairs emitted by the first optical module and the second optical module are defined as acceptable or unacceptable. • The first optical module is fed with a first current value (41b), which generates a luminous flux value between the minimum luminous flux threshold (4b) and the maximum luminous flux threshold (7b). • The second optical module is fed with a second current value (43b), which generates a luminous flux value between the minimum luminous flux threshold (4b) and the maximum luminous flux threshold (7b). • Measure or estimate the temperature in the first optical module and the second optical module; • The color of the light emitted by the first optical module is obtained based on the measured or estimated temperature and the first current value in the first optical module, and the color of the light emitted by the second optical module is obtained based on the measured or estimated temperature and the second current value in the second optical module. • Check whether the color of the light emitted by the first optical module meets the allowed conditions, whether the color of the light emitted by the second optical module meets the allowed conditions, and whether the color pair emitted by the first optical module and the second optical module meets the uniformity standard; • If the color of the light emitted by the first optical module does not meet the allowable conditions, if the color of the light emitted by the second optical module does not meet the allowable conditions, or if the color pair emitted by the first optical module and the second optical module does not meet the uniformity standard, then increase or decrease the first current value and / or the second current value so that the light generated by the first optical module and the second optical module meets the allowable conditions and the uniformity standard. • If the luminous flux value generated by increasing or decreasing the first current value or the second current value (42b; 43b) is lower than the minimum luminous flux threshold (4b) or higher than the maximum luminous flux threshold (7b), then pulse width modulation is performed on the first current value or the second current value to generate a luminous flux value that is between the minimum luminous flux threshold (4b) and the maximum luminous flux threshold (7b).

9. The method according to claim 8, wherein, The increased current value of the first optical module and / or the second optical module is calculated using color and temperature as input values, based on data sheets and / or experimental data.

10. The method according to claim 8, wherein, The first current value is increased, and the increased first current value is calculated based on data obtained from the first optical module, while the second current value is calculated based on the color output by the first optical module and the uniformity standard.

11. The method according to claim 8, wherein, The step of increasing or decreasing the first current value or the second current value includes first defining the increased or decreased current value for the optical module with a higher temperature, and then defining the increased or decreased current value for the optical module with a lower temperature.

12. The method of claim 8, further comprising the step of recording a sequence of incremental current values ​​for each predetermined temperature condition, wherein, The increase or decrease of the first or second current value is based on a recorded sequence of current value increments that depend on the measured or estimated temperature in the first and second optical modules.

13. The method according to claim 8, wherein, At least some steps of the method are performed by a control unit configured to estimate the timing pattern for providing the first current value and the second current value to the first optical module and the second optical module in the following manner: • The control unit (3) is trained using a training dataset to estimate the current values ​​of the first optical module and / or the second optical module; and • Test the control unit (3) using actual current values.

14. A computer program comprising instructions that, when executed by a control unit, cause the control unit to perform the steps of the method according to any one of claims 1 to 13.

15. An automotive lighting device (1), comprising: • Matrix arrangement of solid-state light sources; • Control element (3), which is used to perform the steps of the method according to any one of claims 1 to 13.

16. The automotive lighting device according to claim 15, comprising at least two optical modules (2), wherein, The first optical module includes a first solid-state light source, and the second optical module includes a second solid-state light source, wherein the control element is configured to perform the steps of the method according to claim 8.

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