METHOD FOR CONTROLLING THE ILLUMINATION OF AT LEAST ONE LIGHT SOURCE ARRANGEMENT AT AN END OF AT LEAST ONE LIGHT GUIDE - Patent application

Abstract

The invention relates to a method for controlling the illumination of at least one light source (8A, 8B) arranged at an end of at least one at least partially transparent or translucent light guide (6), the method being executed by a driver device (4) for driving the light source. According to the invention, the driver device is configured for controlling the illumination of the light source by pulse width modulation, the method comprising a first stage of controlling the illumination of the light source according to a first control ramp until a first level of intermediate illumination of the light source is reached and a second stage of controlling the illumination of the light source according to a second control ramp until a second level of illumination of the light source is reached, the slopes of the first and second control ramps being distinguishable.

Description

[Technical field]

[0001] The invention is in the field of lighting, in particular in the field of motor vehicle lighting. The invention particularly relates to a method for controlling the turn-on of at least one light source arranged at one end of at least one light guide that is at least partially transparent or translucent, and to a light emitting device comprising a driver configured to implement such a method. Without being limited in this respect in the context of the invention, the light emitting device may be mounted in a motor vehicle headlamp. The invention is also applicable to light emitting devices intended to illuminate the interior of a vehicle (i.e. light emitting devices mounted for example in the ceiling lights of a vehicle) or to light emitting devices for creating signs or visual animations on a vehicle. Summary of the Invention

[0002] prior art In the field of automotive lighting, light-emitting devices are generally known that are mounted in vehicle headlamps to project a light beam that performs illumination and / or signaling functions related to the measurement of light properties. In particular, to perform a vehicle direction indicator function, the light beam may be a scrolling illumination beam, i.e. creating what is called a "sequential" effect. The latter is conventionally obtained by using a light-emitting device that includes an at least partially transparent or semi-transparent light guide, two essentially point-like light sources (light-emitting diodes) arranged at both ends of the light guide, and a driver for driving the two light sources.

[0003] Published patent document US 10,436,413 B2 discloses such a light emitting device. A driver present in the light emitting device is configured to control the turn-on of each light source. More precisely, the method for controlling the turn-on of the light sources is implemented in the following way: in a first step, a turn-on control according to a first control ramp is used by the driver to turn on the first light source (gradually turn on the light source). In a second step, executed after the first step, a turn-on control according to a second control ramp is used by the driver to turn on the second light source. The first and second control ramps are programmed in the driver and are predetermined such that the first and second light sources reach their respective maximum illumination levels simultaneously. The maximum illumination level of a light source corresponds to the level at which the luminous intensity of the light emitted by this light source is maximum. It will therefore be understood that the first and second control ramps are distinct. The implementation of such a control scheme to turn on two light sources with a time lag between their turning on and their simultaneous reaching of their maximum illumination level makes it possible to obtain a scrolling or "sequential" effect. In other words, the light appears to move in the light guide from the first light source to the second light source until the light guide is fully illuminated. Then, the commands used to turn off the two light sources are sent simultaneously by the driver, and the light sources are turned off completely with a time lag (turn-off control lamps of the first and second light sources with distinct slopes) or simultaneously (turn-off control lamps of the first and second light sources with the same slope).

[0004] However, the scrolling effect produced by such a turn-on control method is relatively rough. Specifically, during the turn-on of the light source, spots or light-emitting segments that do not comply with the lighting regulations of motor vehicles may appear. Furthermore, the illumination beam generated in the light guide by such a method lacks uniformity, which makes the scrolling effect blurred and difficult for users to see. Summary of the Invention The present invention aims to improve the situation.

[0005] One object of the invention is to provide a method for controlling the turn-on of at least one light source, which makes it possible to improve the refinement and uniformity of the scrolling illumination beam generated in the light guide, at reduced costs and without the need for complex electronic design.

[0006] To this end, a first aspect of the invention relates to a method for controlling the turn-on of at least one light source arranged at one end of at least one light guide that is at least partially transparent or translucent, the method being implemented by a light source driver connected to said at least one light source. What is meant here by "light guide" is any optical part that is able to guide light, for example by total internal reflection of this light, from an entrance area to an exit area. Furthermore, what is meant by "driver" is any device for converting an electrical supply provided by an electrical supply network into an electrical supply suitable for the performance of a desired light-emitting function, potentially capable of providing said electrical supply suitable for a light source in order to make it perform said desired light-emitting function. The light source is preferably an essentially point-like light source, such as a light-emitting diode.

[0007] According to the invention, the driver is configured to use pulse width modulation to turn on the light source, the method comprising: - a first stage in which pulse width modulation based control by a first control lamp is used to turn on the light source, the first control lamp being up to a first intermediate illumination level of the light source, i.e. up to a first duty cycle value corresponding to said first intermediate illumination level; a second stage in which a pulse width modulation based control by a second control ramp is used to turn on the light source, the second control ramp being up to a second illumination level of the light source, i.e. up to a second duty cycle value corresponding to said second illumination level, the slopes of the first control ramp and the second control ramp being different, and the luminous intensity of the light emitted by the light source at the second illumination level being greater than the luminous intensity of the light emitted by the light source at the first illumination level; Includes.

[0008] Optionally, but preferably, the second illumination level of the light source corresponds to a maximum illumination level of the light source.

[0009] Optionally, the first and second control ramps are linear ramps obtained from affine functions, i.e. functions such as f(x)=ax+b, where x is a variable and the parameters a and b are constants and one of these two parameters may be zero.

[0010] Thus, through the use of pulse width modulation and the use of two different control lamps to turn on the light sources, the inventive turn-on control method allows for improving the refinement and uniformity of the scrolling illumination beam generated in the light guide. Furthermore, the inventive method allows for a reduction in the number of light sources required to generate the scrolling illumination beam, thereby contributing to a reduction in the cost and simplification of the electronic design of the assembly.

[0011] According to a preferred embodiment of the invention, a turn-on control method is applied to at least one assembly, preferably two assemblies, comprising an at least partially transparent or translucent light guide and two light sources, each light source being arranged at a separate end of the light guide and connected to a driver, the first step of the method comprising: - a first step in which a pulse width modulation based control by a first control lamp is used to turn on a first light source, the first control lamp being up to a first intermediate illumination level of the first light source, i.e. up to a first duty cycle value corresponding to said first intermediate illumination level of the first light source; a second step, executed after the initiation of the first step, in which a pulse width modulation based control by a third control lamp is used to turn on the second light source, the third control lamp being up to a first intermediate illumination level of the second light source, i.e. up to a third duty cycle value corresponding to said first intermediate illumination level of the second light source; Includes.

[0012] Furthermore, the second step of the method is - a first step in which pulse width modulation based control by a second control lamp is used to turn on the first light source to a second illumination level of the first light source, the second control lamp being up to a second duty cycle value corresponding to said second illumination level of the first light source; a second step in which pulse width modulation based control by a fourth control ramp is used to turn on the second light source to a second illumination level of the second light source, the fourth control ramp being up to a fourth duty cycle value corresponding to said second illumination level of the second light source, the slopes of the first and second control ramps and the slopes of the third and fourth control ramps being different, respectively; Includes.

[0013] In this way, by increasing the luminous intensity of the first light source multiple times (at least twice) via multiple distinct turn-on control lamps, and by turning on the second light source with a time difference, a visual scrolling effect is created in the light guide.

[0014] Advantageously, the first step of the first stage is longer than the second step of the second stage in order to stay below the eye saturation threshold for as long as possible, so that the scrolling effect becomes more noticeable.

[0015] Advantageously, the second illumination level of the first light source corresponds to a maximum illumination level of this light source. To this end, the second duty cycle value may be equal to 100%.

[0016] Advantageously, the second illumination level of the second light source corresponds to the illumination level of this light source. To this end, the fourth duty cycle value may be equal to 100%.

[0017] According to one embodiment of the invention, the method further comprises an intermediate step between the second step of the first stage and the second step of the second stage, wherein the illumination level of the second light source remains constant throughout this intermediate step and corresponds to a first intermediate illumination level of the second light source. In other words, a duty cycle corresponding to the first intermediate illumination level of the second light source, also called the third duty cycle value, is applied to the second light source throughout the intermediate step.

[0018] According to one embodiment of the invention, the method further comprises a third step and a fourth step, the third step of the method comprising: - a first step in which pulse width modulation based control by a fifth control lamp is used to turn on the first light source to a first intermediate illumination level of the first light source, the fifth control lamp being up to a first duty cycle value; a second step in which pulse width modulation based control by a sixth control lamp is used to turn on the second light source to a first intermediate illumination level of the second light source, the sixth control lamp being up to a third duty cycle value; Includes.

[0019] Furthermore, the fourth step of the method is: a first step in which pulse width modulation based control by a seventh control lamp is used to turn off the second light source; - a second step performed after the first step, in which a pulse width modulation based control by an eighth control ramp is used to turn off the first light source, and the slopes of the fifth and eighth control ramps and the slopes of the sixth and seventh control ramps are different from each other; Includes.

[0020] This allows for the light guide to create a second scrolling lighting effect following the first scrolling lighting effect, which scrolls in the opposite direction to the first scrolling lighting effect.

[0021] According to one embodiment of the invention, two light sources and a light source driver are arranged in a vehicle light emitting device, preferably in a light emitting device performing a signal function, preferably in a direction indicator device, and the luminous intensity of the light emitted by the first light source at its first illumination level is lower than the luminous intensity of the light emitted by the first light source at its second illumination level. Preferably, the first illumination level remains below the saturation threshold of the observer's eye. This allows the effect of the light scrolling through the guide to be clearly seen in the first step of the first stage.

[0022] According to one embodiment of the invention, the duration of the first step of the first stage of the method is equal to or less than the cumulative duration of the first step of each of the first and second stages of the method. Preferably, the duration of the first step of the first stage of the method is equal to at least half the cumulative duration of the first step of each of the first and second stages of the method, and at most equal to the entire cumulative duration. In one example of the embodiment, the duration of the first step of the first stage of the method is equal to two-thirds of the cumulative duration of the first step of each of the first and second stages of the method (optionally with a final flash at the end of the second stage). In another example of the embodiment, the duration of the first step of the first stage of the method is equal to fifteen-sixteenths of the cumulative duration of the first step of each of the first and second stages of the method (optionally with a final flash at the end of the second stage).

[0023] This ratio between the turn-on times of the first light source, in combination with the feature that the luminous intensity of the light emitted by the first light source at its first illumination level is less than the luminous intensity of the light emitted by the first light source at its second illumination level, allows the saturation threshold of the human eye to remain below for as long as possible, thereby allowing the observer to correctly see the scrolling effect.

[0024] According to one embodiment of the invention, the cumulative duration of the first steps of each of the first and second stages of the method is less than or equal to 200 ms, which allows compliance with the standard in force regulating the turn indicator function of vehicles, namely UNECE regulation 006. In particular, this regulation specifies that a turn indicator must not take longer than 200 ms to turn on.

[0025] According to one embodiment of the invention, the turn-on control method is further applied to at least one additional light source, said at least one additional light source being arranged behind the light guide, the method further comprising a third step in which the light source driver turns on said at least one additional light source to determine the illumination of the light guide. In this embodiment, the presence of one or more additional light sources makes it possible to improve the final illumination of the light guide once the scrolling lighting effect is finished.

[0026] Another subject of the invention relates to a vehicle lighting device comprising at least one light guide which is at least partially transparent or translucent, at least one light source arranged at one end of the light guide, and a light source driver connected to said at least one light source, said driver being configured to implement the turn-on control method according to the invention to turn on said at least one light source.

[0027] According to one embodiment of the invention, said at least one light guide comprises, on its outer surface, at least one striation extending substantially transversely to the main direction of extension of the light guide, the presence of these striations on the outer surface of the light guide making it possible to improve the optical diffusion of the light rays emitted by the light source or light sources.

[0028] According to a preferred embodiment of the invention, the light emitting device comprises at least one assembly, preferably two assemblies, comprising an at least partially transparent or translucent light guide and two light sources, each light source being arranged at a separate end of the light guide, and a driver connected to each light source and configured to implement the turn-on control method according to the invention to turn on each light source.

[0029] According to one embodiment of the invention, a light source is arranged at each end of a plurality of at least partially transparent or translucent light guides. This embodiment makes it possible to reduce the number of light sources used.

[0030] According to one embodiment of the invention, the light guides are arranged to define substantially the shape of a corolla, with the light source being located in the center of the corolla. According to one example embodiment, a "tulip" shaped portion can be used to direct light emitted by the light source into each light guide.

[0031] According to another embodiment, additional light sources may be placed at the other end of each light guide, or the other ends of the light guides may be grouped together by "tulip" shaped sections (two ends per tulip) to reduce the number of additional light sources.

[0032] According to one preferred embodiment of the invention, the light emitting device is a vehicle direction indicator.

[0033] According to one embodiment of the invention, the light guide is at least partially made of transparent or translucent plastic, in particular polycarbonate (also called PC) or polymethylmethacrylate (also called PMMA).

[0034] Another subject of the invention relates to a vehicle headlamp, in particular a vehicle headlamp for motor vehicles, comprising a light-emitting device according to the invention.

[0035] By "vehicle" herein is meant any kind of vehicle, such as a motorized vehicle, a moped, a bike, a warehouse robot, or any other machine capable of carrying at least one passenger or intended to transport people or goods.

[0036] Another subject of the invention relates to the use of a light-emitting device according to the invention for performing a signalling function relating to the measurement of the properties of the light of a vehicle, in particular a vehicle direction indication function. [Brief description of the drawings]

[0037] Other features and advantages of the invention will become apparent from consideration of the following detailed description and the accompanying drawings, in which: [Figure 1] FIG. 1 is a schematic diagram of a side view of a light emitting device according to a first embodiment of the invention, the light emitting device comprising two light sources and a driver for driving the light sources. [Diagram 2] FIG. 2 is a schematic diagram of a top view of a light emitting device according to a second embodiment of the invention, the light emitting device comprising a light source and a driver for driving the light source. [Diagram 3] FIG. 3 is a flow chart illustrating a method for controlling the turn-on of at least one light source according to the invention, which method is implemented by the driver of FIG. 1 or FIG. [Figure 4] FIG. 4 is a set of two graphs showing the change as a function of time in the control used to turn on the two light sources of FIG. 1 according to the first control law. [Diagram 5] FIG. 5 is a set of four graphs showing the change as a function of time in the raw control used to turn on the two light sources of FIG. 1 according to the second control law, and the change as a function of time in the control signals applied in real time to these two light sources according to the second control law converted to the CIE XYZ 1931 color space laws.

[0038] In this document, the terms "horizontal", "vertical" or "side", "bottom", "top", "high", "low" and "side" are defined with respect to the orientation in which a lighting device according to the invention, or a component forming part of a lighting device according to the invention, is intended to be mounted on a vehicle. In particular in this patent application, the term "vertical" refers to an orientation perpendicular to the horizon and the term "horizontal" refers to an orientation parallel to the horizon. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] Detailed Description FIG. 1 is a schematic diagram of a side view of a light emitting device 1 according to a first embodiment of the invention.

[0040] The light emitting device 1 comprises an assembly 2 and a light source driver 4. The assembly 2 comprises an at least partially transparent or translucent light guide 6 and two light sources 8A, 8B. Preferably, the light emitting device 1 comprises two assemblies 2, although only one assembly 2 is shown in Fig. 1 for clarity, and the two assemblies 2 are placed vertically one above the other. Also, preferably, the assembly 2 further comprises at least one additional light source arranged behind the light guide 6, which is not shown in Fig. 1 for clarity.

[0041] The light guide 6 is advantageously a tubular light guide elongated in a substantially horizontal main extension direction D1. Preferably, the light guide 6 comprises, on its outer surface, striations 10 extending substantially transversely to the main extension direction D1 of the light guide 6. The light guide 6 is advantageously made of an at least partially transparent or translucent plastic, in particular polycarbonate (also called PC) or polymethylmethacrylate (also called PMMA).

[0042] Each light source 8A, 8B is arranged at a separate end of the light guide 6. Each light source 8A, 8B is advantageously an essentially point-like light source, in particular a semiconductor light source such as, for example, a light-emitting diode.

[0043] A driver 4 is connected to each of the light sources 8A, 8B and configured to implement a method for controlling the turn-on of the light sources 8A, 8B according to an example embodiment of the invention, as described below. The driver 4 is configured to turn on each light source 8A, 8B using pulse width modulation based control.

[0044] Figure 2 is a schematic diagram of a view from above of a light emitting device 12 according to a second embodiment of the invention. In figures 1 and 2, elements designated with the same reference numbers are similar and therefore will not be described in more detail below.

[0045] The light emitting device 12 comprises a light source driver 4, four light guides 6 that are at least partially transparent or translucent, and a single light source 8C. The driver 4 is connected to the light source 8C and is configured to turn on the light source 8C using pulse width modulation based control.

[0046] As shown in FIG. 2, the light source 8C is arranged at one respective end of each of the light guides 6. More precisely, the light guides 6 are arranged to define substantially a corolla shape 14, the light source 8C being arranged in the center of the corolla 14. By way of example, a "tulip" shaped section (not shown in FIG. 2 for clarity) may be used to direct the light emitted by the light source 8C into each light guide 6. The light source 8C is advantageously an essentially point-like light source, in particular a semiconductor light source, for example a light-emitting diode. According to a variant of the embodiment, an additional light source (not shown) may be arranged at the other end of each light guide 6. Alternatively, the other ends of the light guides 6 may be grouped together by a "tulip" shaped section (two ends per tulip) so as to reduce the number of additional light sources.

[0047] A method for controlling the turn-on of at least one light source according to the invention, implemented by a driver 4, will now be described with reference to Fig. 3. The method may for example be implemented by a driver of a light-emitting device 1 according to the first embodiment, in which case the method applies to both light sources 8A, 8B; or else by a driver of a light-emitting device 12 according to the second embodiment, in which case the method applies to a single light source 8C. For ease of explanation, the method will be described below with reference to a light-emitting device 1 according to the first embodiment with its two light sources 8A, 8B. At the start of the method the two light sources 8A, 8B are turned off.

[0048] The method includes a first stage 20. This first stage 20 includes a first step 22 in which a pulse width modulation based control according to a first control ramp 23 is used to turn on the first light source 8A up to a first duty cycle value corresponding to a first intermediate illumination level of the first light source 8A, where in the example shown in Figures 4 and 5 the first duty cycle value is equal to 40%.

[0049] The first control lamp 23 is shown in Figures 4 and 5. In particular, Figures 4 and 5 show the variation as a function of time in the control used to turn on the two light sources 8A, 8B of Figure 1 according to two different control laws, where the pulse width modulation based turn on control is represented by its duty cycle value shown on the Y axis of the graph. The X axis of the graph corresponds to the time of variation in the control.

[0050] The variation as a function of time in the control used to turn on the first light source 8A and the second light source 8B according to the first control law is shown in Fig. 4 by the curves C1 and C2, respectively. The variation as a function of time in the low control used to turn on the first light source 8A and the second light source 8B according to the second control law is shown in Fig. 5 by the curves C3 and C4, respectively. The variation as a function of time of the control signal applied in real time to the first light source 8A and the second light source 8B according to the second control law transposed to the CIE XYZ 1931 color space law is shown in Fig. 5 by the curves C5 and C6, respectively.

[0051] Such a CIE XYZ 1931 color space law (as shown by the curves C5, C6 in FIG. 5) gives in particular a luminance value as a function of a pulse-width modulation-based turn-on control value, allowing a smooth turn-on of the two light sources 8A, 8B. The CIE XYZ 1931 color space law is typically centered on white, but may alternatively be adjusted to center on yellow, in particular for yellow light-emitting diodes. Alternatively, control laws other than the CIE XYZ 1931 color space law can be envisaged for controlling the turn-on of the two light sources 8A, 8B, such as, for example, linear laws.

[0052] The first stage 20 includes a second step 24, executed after the start of the first step 22, in which a pulse width modulation based control according to a first control ramp 25 is used to turn on the second light source 8B up to a third duty cycle value corresponding to a first intermediate illumination level of the second light source 8B. In the example shown in Fig. 4, the third duty cycle value is equal to 50%. In the example shown in Fig. 5, the third duty cycle value is equal to 10%.

[0053] The time interval separating the start of the second step 24 of the first phase 20 from the start of the first step 22 is called t1 in Figures 4 and 5. This time interval t1 may be parameterized in advance depending on the desired characteristics of the scroll effect. The duration of the first step 22 of the first phase 20 is called t2 in Figure 5. In the particular example of Figure 4, the duration of the first step 22 and the time interval separating the start of the first step 22 from the start of the second step 24 are identical and called t1.

[0054] The method includes a second stage 26. This second stage 26 includes a first step 28 in which a pulse width modulation based control according to a second control ramp 29 is used to turn on the first light source 8A to a second illumination level of the first light source 8A, the second control ramp being up to a second duty cycle value. The slopes of the first and second ramps 23, 29 controlling the turn-on of the first light source 8A are distinct. In the particular example of the embodiment in FIG. 5, the slope of the first ramp 23 controlling the turn-on of the first light source 8A is zero. The luminous intensity of the light emitted by the first light source 8A at its second illumination level is greater than the luminous intensity of the light emitted by the first light source 8A at its first illumination level. Preferably, the second illumination level of the first light source 8A corresponds to a maximum illumination level of this light source 8A. To this end, in the example shown in FIGS. 4 and 5, the second duty cycle value is equal to 100%.

[0055] The cumulative time for the first steps 22, 28 of the first and second stages of the method is t total Preferably, the duration t1, t2 of the first step 22 of the first stage 20 is at least this cumulative duration t total t1, t2 of the first step 22 of the first phase 20 is equal to half of this cumulative duration t total Also preferably, in the context of this particular vehicle indicator application, the cumulative duration t total, 200 ms or less. Also preferably, in the context of the same particular application, the luminous intensity of the light emitted by the first light source 8A at its first illumination level is 0.4 times or less the luminous intensity of the light emitted by the first light source 8A at its second illumination level, as shown in FIG.

[0056] The second stage 26 includes a second step 30 in which a pulse width modulation based control according to a second control ramp 31 is used to turn on the second light source 8B to a second illumination level of the second light source 8B, the second control ramp being up to a fourth duty cycle value. In the example shown in Fig. 4, the fourth duty cycle value is equal to 100%. In the example shown in Fig. 5, the fourth duty cycle value is equal to 40%. The slopes of the first and second ramps 25, 31 controlling the turn-on of the second light source 8B are distinct.

[0057] In the particular example of the embodiment in Figures 4 and 5, the first and second lamps 25, 31 controlling the turn-on of the second light source 8B are separated by an intermediate plateau 33 of zero slope. This intermediate plateau 33 corresponds to a constant turn-on control signal corresponding to a first intermediate illumination level of the second light source 8B. In the example shown, the control signal of the intermediate plateau consists of applying a third duty cycle value for the duration of the intermediate plateau 33.

[0058] As a variant (not shown), the first and second lamps 25, 31 controlling the turn-on of the second light source 8B do not have to be separated by such an intermediate plateau. The turn-on of the second light source 8B is thus offset in time with respect to the turn-on of the first light source 8A, and both light sources reach their maximum luminous intensity value at the same time. The luminous intensity of the light emitted by the second light source 8B at its second illumination level is greater than the luminous intensity of the light emitted by the second light source 8B at its first illumination level. Preferably, the second illumination level of the second light source 8B corresponds to the maximum illumination level of this light source 8B. This case corresponds to the graph shown in FIG. 4. Here, the fourth duty cycle value corresponding to the second illumination level of the second light source is equal to 100%.

[0059] Also preferably, the first step 22 of the first stage 20 is longer than the second step 30 of the second stage 26. In the particular embodiment shown in Fig. 5, the luminous intensity of the light emitted by the second light source 8B at its second illumination level (curve C6) is less than the luminous intensity of the light emitted by the first light source 8A at its second illumination level (curve C5). This makes it possible to prevent visual effects that may result from a "backflow of light" from the second light source 8B to the first light source 8A.

[0060] The first and second stages 20, 26 may overlap, as shown in Fig. 4 (in particular, in this figure, the second stage 26 starts before the end of the first stage 20), or they may be performed sequentially, as shown in Fig. 5 (in this figure, the second stage 26 starts when the first stage 20 is finished). The first and second stages 20, 26 make it possible to obtain a scrolling effect in the light guide 6 in the direction from the first light source 8A to the second light source 8B, with better illumination beam fineness and uniformity than prior art solutions.

[0061] Preferably, the method comprises a next step 32, not shown in figures 4 and 5. In this next step 32, the driver 4 turns on at least one additional light source arranged behind the light guide 6 (such additional light source is not shown in the figures), thereby ensuring illumination of the light guide 6.

[0062] In a final step 35, the driver 4 turns off the first and second light sources 8A, 8B as well as the optional additional light source or light sources. If the light emitting device 1, 12 is a vehicle lighting and / or signaling light, in particular a direction indicator, the first and second light sources 8A, 8B as well as the optional additional light source or light sources are turned off at the end of the total duration of the method, which is for example substantially equal to 400 ms.

[0063] Instead of the final stage 35, the method may also include a next stage 34, not shown in Figs. 4 and 5. This next stage 34 includes a first step 36 in which a pulse-width modulation based control according to a first control ramp is used to turn on the first light source 8A to a first intermediate illumination level of the first light source 8A, the first control ramp being up to a first duty cycle value. Stage 34 includes a second step 38 in which a pulse-width modulation based control according to a first control ramp is used to turn on the second light source 8B to a first intermediate illumination level of the second light source 8B, the first control ramp being up to a third duty cycle value. The method may also include another stage 40. This stage 40 includes a first step 42 in which a pulse-width modulation based control according to a second control ramp is used to turn off the second light source 8B. The slopes of the first and second ramps controlling the turn-off of the second light source 8B are distinguishable. Stage 40 includes a second step 44, performed after first step 42, in which a pulse width modulation based control by a second control ramp is used to turn off first light source 8A. The slopes of the first and second ramps controlling the turn-off of first light source 8A are distinct.

[0064] These stages 34, 40, which make it possible to obtain a second scrolling light effect in the light guide 6 in the opposite direction to the first scrolling effect (hence in the direction from the second light source 8B towards the first light source 8A), may be overlapping (in which case stage 40 starts before the end of stage 34) or may actually be performed sequentially (in which case stage 40 starts when stage 34 has been completed).

[0065] The illumination beams generated by the light sources 8A, 8B of the light-emitting device 1 may advantageously be used to perform regulating functions relating to the measurement of light properties, in particular vehicle illumination and / or signaling functions relating to the measurement of light properties, and preferably vehicle direction indication functions. The illumination beams generated by the light-emitting devices 1, 12 may also be used to perform functions relating to the measurement of light properties of the "daytime running light" type, or it may be used in the interior lighting of the vehicle (where the light-emitting device is for example mounted in the ceiling light of the vehicle) or indeed for generating signs or visual animations on the vehicle.

Claims

1. 1. A method for controlling the turning on of at least one light source (8A, 8B; 8C) arranged at one end of at least one light guide (6) that is at least partially transparent or translucent, the method being performed by a light source driver (4) connected to said at least one light source (8A, 8B; 8C), The driver (4) is configured to use pulse width modulation based control to turn on the light sources (8A, 8B; 8C): a first stage (20) in which a pulse width modulation based control by a first control lamp (23, 25) is used to turn on said light source (8A, 8B; 8C), said first control lamp being up to a first duty cycle value corresponding to a first intermediate illumination level of said light source (8A, 8B; 8C); a second stage (26) in which a pulse width modulation based control by a second control lamp (29, 31) is used to turn on the light source, the second control lamp up to a second duty cycle value corresponding to a second illumination level of the light source, the slopes of the first and second control lamps (23, 25, 29, 31) being different, and the luminous intensity of the light emitted by the light source (8A, 8B; 8C) at its second illumination level being greater than the luminous intensity of the light emitted by the light source (8A, 8B; 8C) at its first illumination level; Including, A method characterized by:

2. The turn-on control method is applied to at least one assembly (2), preferably two assemblies, said at least one assembly (2) comprising an at least partially transparent or translucent light guide (6) and two light sources (8A, 8B), each light source (8A, 8B) arranged at a different end of the light guide (6) and connected to the driver (4), and the first step (20) of the method comprises: a first step (22) in which a pulse width modulation based control by a first control lamp (23) is used to turn on a first light source (8A), said first control lamp being up to a first duty cycle value corresponding to a first intermediate illumination level of said first light source (8A); a second step (24) carried out after the start of said first step (22), in which a pulse width modulation based control by a third control lamp (25) is used to turn on a second light source (8B), said third control lamp up to a third duty cycle value corresponding to a first intermediate illumination level of said second light source (8B); Including, The second step (26) of the method comprises: a first step (28) in which pulse width modulation based control by a second control lamp (29) is used to turn on the first light source (8A) to a second illumination level of the first light source (8A), the second control lamp being up to a second duty cycle value corresponding to the second illumination level of the first light source; a second step (30) in which pulse width modulation based control by a fourth control lamp (31) is used to turn on the second light source (8B) to a second illumination level of the second light source (8B), the fourth control lamp being up to a fourth duty cycle value corresponding to the second illumination level of the second light source; Including, the slopes of the first and second control ramps (23, 29) and the third and fourth control ramps (25, 31) are different; The method of claim 1.

3. 3. The method of claim 2, further comprising an intermediate step (35) between the second step (24) of the first stage (20) and the second step (30) of the second stage (26), wherein the illumination of the second light source (6B) remains constant throughout this intermediate step and corresponds to the first intermediate illumination level of the second light source (8B).

4. further comprising a third stage (34) and a fourth stage (40); The third step (34) of the method comprises: a first step (36) in which pulse width modulation based control by a fifth control lamp is used to turn on the first light source (8A) to the first intermediate illumination level of the first light source (8A), the fifth control lamp being up to the first duty cycle value; a second step (38) in which pulse width modulation based control by a sixth control lamp is used to turn on the second light source (8B) to the first intermediate illumination level of the second light source (8B), the sixth control lamp being up to the third duty cycle value; Including, The fourth step (40) of the method comprises: a first step (42) in which a pulse width modulation based control by a seventh control lamp is used to turn off said second light source (8B); a second step (44) carried out after said first step, in which pulse width modulation-based control by an eighth control lamp is used to turn off said first light source (8A); Including, the fifth control ramp and the eighth control ramp, and the sixth control ramp and the seventh control ramp have different slopes; The method of claim 2.

5. 3. The method according to claim 2, wherein the two light sources (8A, 8B) and the light source driver (4) are arranged in a vehicle light-emitting device (1), preferably in a light-emitting device performing a signaling function, preferably in a direction indicating light-emitting device, and wherein the luminous intensity of the light emitted by the first light source (8A) at its first lighting level is lower than the luminous intensity of the light emitted by the first light source (8A) at its second lighting level.

6. The duration (t １ , t ２ ) is the cumulative duration (t ｔｏｔａｌ 3. The method of claim 2, wherein:

7. 2. The method of claim 1, wherein the turn-on control method is further applied to at least one additional light source, the at least one additional light source being arranged behind the light guide (6), and the method further comprises a third step (32) of turning on the at least one additional light source so that the light source driver (4) determines the illumination of the light guide (6).

8. The device comprises at least one light guide (6) that is at least partially transparent or translucent, at least one light source (8A, 8B; 8C) arranged at one end of the light guide (6), and a light source driver (4) connected to the at least one light source (8A, 8B; 8C), 10. A vehicle lighting device (1; 12), characterized in that the driver (4) is configured to perform the turn-on control method according to claim 1 so as to turn on the at least one light source (8A, 8B; 8C).

9. 9. A light-emitting device (1; 12) according to claim 8, wherein the at least one light guide (6) has at least one striated portion (10) on its outer surface, which extends substantially transversely to the main extension direction (D1) of the light guide (6).

10. 10. The light emitting device (1) according to claim 8 or 9, wherein the light emitting device (1) comprises at least one assembly (2), preferably two assemblies, the at least one assembly (2) comprising an at least partially transparent or translucent light guide (6) and two light sources (8A, 8B), each light source (8A, 8B) being arranged at a different end of the light guide (6), the driver (4) being connected to each of the light sources (8A, 8B) and configured to perform the turn-on control method according to one of claims 2 to 6 or the turn-on control method according to claim 7 when it is dependent on claim 2, so as to turn on each of the light sources (8A, 8B).

11. 10. A light emitting device (12) according to claim 8 or 9, wherein the light sources (8C) are arranged at the respective ends of a plurality of light guides (6) that are at least partially transparent or translucent.

12. 12. The lighting device (12) according to claim 11, wherein the light guides (6) are arranged to substantially define a corolla shape (14), and the light source (8C) is arranged in the center of the corolla (14).

13. The light emitting device (1; 12) according to claim 8, wherein said light emitting device (1; 12) is a vehicle direction indicator light.

14. A vehicle headlamp comprising a light emitting device (1; 12) according to claim 8.

15. Use of a light emitting device (1; 12) according to claim 8 to perform a vehicle photometric signalling function, in particular a vehicle direction indicating function.

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