METHOD FOR OPERATING AN AUTOMOTIVE LIGHTING DEVICE AND AUTOMOTIVE LIGHTING DEVICE

Abstract

The invention provides a method for operating an automotive lighting device including the providing a first preliminary current profile, calculating a first preliminary derating time associated to the first preliminary current profile, providing a second preliminary current profile, calculating a second preliminary derating time associated to the second preliminary current profile, feeding the first light module with a first current profile which provides a total amount of current lower than the first preliminary amount of current, and feeding the second light module with a second current profile which provides a total amount of current higher than the second preliminary amount of current.

Claims

1. A method for operating an automotive lighting device including at least a first light module and a second light module, each one of the light modules including solid-state light sources, the method comprising: providing a first preliminary current profile to feed the first light module so that the first light module produces a light flux greater than a first flux threshold value, calculating a first preliminary derating time associated to the first preliminary current profile, wherein the first preliminary current profile involves a first preliminary amount of current until the first preliminary derating time; providing a second preliminary current profile to feed the second light module so that the second light module produces a light flux greater than a second flux threshold value calculating a second preliminary derating time associated to the second preliminary current profile, the second preliminary derating time being higher than the first preliminary derating time, wherein the second preliminary current profile involves a second preliminary amount of current until the second preliminary derating time; feeding the first light module with a first current profile which provides a total amount of current lower than the first preliminary amount of current, calculated until the first preliminary derating time; and feeding the second light module with a second current profile which provides a total amount of current higher than the second preliminary amount of current, calculated until the second preliminary derating time.

2. The method according to claim 1, wherein the first current profile and the second current profile includes starting with a first current value and increasing the current value when a predetermined condition is reached.

3. The method according to claim 2, further comprising obtaining the first current value with a machine learning algorithm which obtains information from vehicle sensors.

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

5. The method according to claim 2, wherein the predetermined condition includes the fact that a measured luminous flux value falls below the corresponding flux threshold value.

6. The method according to claim 2, further comprising obtaining a light source temperature and wherein the predetermined condition includes the fact that the light source temperature reaches a predetermined value.

7. The method according to claim 2, wherein the predetermined condition includes the fact that a time limit has been reached.

8. The method according to claim 2, wherein increasing the current value includes increasing the current value from a first value to a second value, the second value being greater than the first value but lower than 1.1 times the first value.

9. The method according to claim 8, wherein increasing the current value includes increasing the current value from a first value to a second value, the second value being lower than 1.05 times the first value.

10. The method according to claim 9, wherein increasing the current value includes increasing the current value from a first value to a second value, the second value being lower than 1.03 times the first value.

11. The method according to claim 1, further comprising recording a sequence of current value increments for predetermined conditions.

12. The method according to claim 1, wherein the first light module is a low beam module and the second light module is a high beam module.

13. The method according to claim 1, wherein the method is applied to at least 10% of the light sources of the corresponding light module.

14. An automotive lighting device comprising: a first light module comprising a plurality of solid-state light sources; a second light module comprising a plurality of solid-state light sources; and a control element configured to provide a first preliminary current profile to feed the first light module so that the first light module produces a light flux greater than a first flux threshold value, calculate a first preliminary derating time associated to the first preliminary current profile, wherein the first preliminary current profile involves a first preliminary amount of current until the first preliminary derating time; provide a second preliminary current profile to feed the second light module so that the second light module produces a light flux greater than a second flux threshold value calculate a second preliminary derating time associated to the second preliminary current profile, the second preliminary derating time being higher than the first preliminary derating time, wherein the second preliminary current profile involves a second preliminary amount of current until the second preliminary derating time; feed the first light module with a first current profile which provides a total amount of current lower than the first preliminary amount of current, calculated until the first preliminary derating time; and feed the second light module with a second current profile which provides a total amount of current higher than the second preliminary amount of current, calculated until the second preliminary derating time.

15. The automotive lighting device according to claim 14, further comprising a thermistor to measure the temperature of the solid-state light sources.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0044] In some particular embodiments, the automotive lighting device comprises further comprising a thermistor intended to measure the temperature of the solid-state light sources.

[0045] FIG. 1 shows a general perspective view of an automotive lighting device according to the invention;

[0046] FIG. 2 shows a graphic scheme of the standard operation of the two light modules of the lighting device when no method according to the invention applies.

[0047] FIG. 3 shows a different graph for the same phenomenon, but applied only to the first light module.

[0048] FIG. 4 shows the evolution of the flux-temperature curve of the first module when an operation according to the method of the invention is followed.

[0049] FIG. 5 shows this comparison for the second light module.

[0050] FIG. 6 shows the new graphic scheme of the operation of the two light modules of the lighting device when a method according to the invention is used.

DETAILED DESCRIPTION OF THE INVENTION

[0051] In these figures, the following reference numbers have been used: [0052] 1 First light module [0053] 2 Second light module [0054] 3 LED [0055] 4 Control element [0056] 5 Thermistors [0057] 6 Temperature threshold [0058] 10 Lighting device [0059] 11 First preliminary curve for first module [0060] 11′ Invention curve for the first module [0061] 12 First preliminary curve for second module [0062] 12′ Invention curve for the second module [0063] 21 First preliminary derating time for first module [0064] 21′ Invention derating time for the first light module [0065] 22 Second preliminary derating time for second module [0066] 22′ Invention derating time for the second light module [0067] 31 Original curve of a state of the art method for the first light module [0068] 41 Curve of the invention for the first light module [0069] 51 Original curve of a state of the art method for the second light module [0070] 61 Curve of the invention for the second light module [0071] 100 Automotive vehicle

[0072] The example embodiments are described in sufficient detail to enable those of ordinary skill in the art to embody and implement the systems and processes herein described. It is important to understand that embodiments can be provided in many alternate forms and should not be construed as limited to the examples set forth herein.

[0073] Accordingly, while embodiment can be modified in various ways and take on various alternative forms, specific embodiments thereof are shown in the drawings and described in detail below as examples. There is no intent to limit to the particular forms disclosed. On the contrary, all modifications, equivalents, and alternatives falling within the scope of the appended claims should be included.

[0074] FIG. 1 shows a general perspective view of an automotive lighting device according to the invention.

[0075] This lighting device 10 is installed in an automotive vehicle 100 and comprises

[0076] a first light module 1 comprising a plurality of LEDs 3;

[0077] a second light module 2 comprising a plurality of LEDs 3;

[0078] a control element 4;

[0079] a plurality of thermistors 5 intended to measure the temperature in different sections of the first and second light modules.

[0080] Each of the light modules is a high-resolution module, having a resolution greater than 2000 pixels. However, no restriction is attached to the technology used for producing the projection modules.

[0081] A first example of this matrix configuration comprises a monolithic source. This monolithic source comprises a matrix of monolithic electroluminescent elements arranged in several columns by several rows. In a monolithic matrix, the electroluminescent elements can be grown from a common substrate and are electrically connected to be selectively activatable either individually or by a subset of electroluminescent elements. The substrate may be predominantly made of a semiconductor material. The substrate may comprise one or more other materials, for example non-semiconductors (metals and insulators). Thus, each electroluminescent element/group can form a light pixel and can therefore emit light when its/their material is supplied with electricity. The configuration of such a monolithic matrix allows the arrangement of selectively activatable pixels very close to each other, compared to conventional light-emitting diodes intended to be soldered to printed circuit boards. The monolithic matrix may comprise electroluminescent elements whose main dimension of height, measured perpendicularly to the common substrate, is substantially equal to one micrometre.

[0082] The monolithic matrix is coupled to the control centre so as to control the generation and/or the projection of a pixelated light beam by the matrix arrangement. The control centre is thus able to individually control the light emission of each pixel of the matrix arrangement.

[0083] Alternatively to what has been presented above, the matrix arrangement may comprise a main light source coupled to a matrix of mirrors. Thus, the pixelated light source is formed by the assembly of at least one main light source formed of at least one light emitting diode emitting light and an array of optoelectronic elements, for example a matrix of micro-mirrors, also known by the acronym DMD, for “Digital Micro-mirror Device”, which directs the light rays from the main light source by reflection to a projection optical element. Where appropriate, an auxiliary optical element can collect the rays of at least one light source to focus and direct them to the surface of the micro-mirror array.

[0084] Each micro-mirror can pivot between two fixed positions, a first position in which the light rays are reflected towards the projection optical element, and a second position in which the light rays are reflected in a different direction from the projection optical element. The two fixed positions are oriented in the same manner for all the micro-mirrors and form, with respect to a reference plane supporting the matrix of micro-mirrors, a characteristic angle of the matrix of micro-mirrors defined in its specifications. Such an angle is generally less than 20° and may be usually about 12°. Thus, each micro-mirror reflecting a part of the light beams which are incident on the matrix of micro-mirrors forms an elementary emitter of the pixelated light source. The actuation and control of the change of position of the mirrors for selectively activating this elementary emitter to emit or not an elementary light beam is controlled by the control center.

[0085] In different embodiments, the matrix arrangement may comprise a scanning laser system wherein a laser light source emits a laser beam towards a scanning element which is configured to explore the surface of a wavelength converter with the laser beam. An image of this surface is captured by the projection optical element.

[0086] The exploration of the scanning element may be performed at a speed sufficiently high so that the human eye does not perceive any displacement in the projected image.

[0087] The synchronized control of the ignition of the laser source and the scanning movement of the beam makes it possible to generate a matrix of elementary emitters that can be activated selectively at the surface of the wavelength converter element. The scanning means may be a mobile micro-mirror for scanning the surface of the wavelength converter element by reflection of the laser beam. The micro-mirrors mentioned as scanning means are for example MEMS type, for “Micro-Electro-Mechanical Systems”. However, the invention is not limited to such a scanning means and can use other kinds of scanning means, such as a series of mirrors arranged on a rotating element, the rotation of the element causing a scanning of the transmission surface by the laser beam.

[0088] In another variant, the light source may be complex and include both at least one segment of light elements, such as light emitting diodes, and a surface portion of a monolithic light source.

[0089] Since there is a great amount of light sources very close to each other, thermal control is very important to ensure a good performance and efficiency.

[0090] FIG. 2 shows a graphic scheme of the standard operation of the two light modules of the lighting device when no method according to the invention applies.

[0091] According to this figure, the first light module follows the first curve 11, increasing its temperature with time. When a first preliminary derating time 21 is reached, the first light module reaches the maximum temperature threshold 6 and needs to be derated to avoid damages.

[0092] Analogously, the second light module, if installed alone, would follow the second curve 12, increasing its temperature with time. When a second preliminary derating time 22 was reached, the second light module would have reached the maximum temperature threshold 6 and needs to be derated to avoid damages. The fact is that, since the second light module is installed together with the first light module, which has a lower derating time, the second light module would need to be derated at the first preliminary derating time, which happens before the second preliminary derating time, to guarantee the homogeneity of the beam and to respect the regulations, which does not allow the use of a high beam module without operating the low beam module.

[0093] FIG. 3 shows a different graph for the same phenomenon, but applied only to the first light module. In this graph, the luminous flux is shown against the temperature. While the temperature increases (which happens while the time increases), the light module will follow the curve 31 until reaching the temperature threshold 6, and will be derated to a lower intensity, which causes a lower luminous flux and a lower temperature. However, the temperature threshold is reached again, causing a new derating.

[0094] This first curve 31 defines a first preliminary amount of current until the first preliminary derating time and the second curve 12 defines a second preliminary amount of current until the second preliminary derating time.

[0095] FIG. 4 shows the evolution of the flux-temperature curve 41 of the first module when an operation according to the method of the invention is followed.

[0096] Dashed lines are used for the preliminary current profile 31 of FIG. 2 (therefore, only for the first light module), for a better comparison between both methods.

[0097] The first light module is fed with a first current value which 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 which obtains information from vehicle sensors and is trained to provide a value which provides the longest derating time possible for first light module. This lower current value will provide a lower luminous flux. To compensate this difference in the luminous flux, and to provide a better flux homogeneity, as will be shown in FIG. 5, the second light module is fed with a first current value which is higher than the corresponding first value of the second preliminary current profile.

[0098] The increases in the current value of curve 41 are carried out from a first value to a second value, wherein the second value is slightly higher than the first value, typically between 1.01 and 1.05 times the first value. The current increase is low but enough to keep enough luminous flux for a longer period of time.

[0099] Since the first value of the second current profile is higher than expected, the sum of both fluxes will be compensated, and an acceptable value will be obtained. Therefore, the current value will be increased with time, when a low value of the total luminous flux (understood as the sum of the luminous flux of both first and second light modules) is achieved.

[0100] Since the total amount of current for the first light module (measured until the first preliminary derating time) is lower than in the case of FIG. 2, the derating time will be higher than the first preliminary derating time, as will be shown in FIG. 6.

[0101] FIG. 5 shows this comparison for the second light module. Here, curve 51 represents the method of the state of the art and curve 61 represents the present invention. As has been previously announced, curve 61 represents higher current values than in the case of FIG. 2, which lead to a higher total amount of current.

[0102] FIG. 6 shows the new graphic scheme of the operation of the two light modules of the lighting device when a method according to the invention is used.

[0103] Curves 11′ and 12′ show the new evolution of the temperature with time. In the event of the first module, it is slower than the curve 11. In the event of the second module, it is faster than curve 12.

[0104] As has been previously announced, the use of lower current values in the first light module, which involved a lower total amount of current, causes a derating time 21′ which is higher than the first preliminary derating time. On the contrary, the use of higher values in the second light module, which involved a higher total amount of current, causes a derating time 22′ which is lower than the second preliminary derating time. However, luminous flux homogeneity is maintained and the minimum derating time (the first one) has been enlarged