EP4611489A1

EP4611489A1 - Luminous device with several types of light sources

Info

Publication number: EP4611489A1
Application number: EP24160725.8A
Authority: EP
Inventors: Miguel-Angel CANTUDO; Manuel HERNANDEZ-CLEDERA; Jesus JURADO; Juan MORIS; Jose-Ramon MARTINEZ-PEREZ
Original assignee: Valeo Vision SAS
Current assignee: Valeo Vision SAS
Priority date: 2024-02-29
Filing date: 2024-02-29
Publication date: 2025-09-03
Also published as: WO2025181382A1

Abstract

The invention offers a luminous device that enables a plurality of different types of light source to be supplied by means of a single control unit. In preferred embodiments of the invention, several types of light sources emitting different colors of light are connected to a single control unit. A control unit, which is either a dedicated module or integrated into the control device, is used to selectively power one of the light source types to the exclusion of the others .

Description

This invention is related to the field of motor vehicle lighting, and in particular it concerns a luminous signalling device.
A light-emitting diode, LED, is a semiconductor electronic component capable of emitting light of a predetermined wavelength when an electrical voltage at least equal to a threshold value is applied to its terminals. Above this threshold value, known as the forward voltage, the intensity of the luminous flux emitted by an LED generally increases proportionally with the average intensity of the electrical supply current. Their small size and low power consumption make LED components particularly attractive for automotive light modules. LED light sources can be used, for example, to create distinctive optical signatures by placing components along predetermined contours.
Typically, when several light colours are required, for example to perform different regulatory functions, the number of control circuits and/or power supply control circuits is multiplied by the number of light source types required. Each type of light source is controlled by a dedicated module, which results in significant additional costs, as well as taking up a lot of space in the limited space available to create a luminous device for a motor vehicle.
The aim of the invention is to overcome at least one of the problems posed by the prior art. In particular, the invention aims to provide a luminous device and a method for powering a plurality of different types of light source, using a single control unit.
According to a first aspect of the invention, a luminous device for a motor vehicle is proposed. The luminous device comprises :

two arrangements of semiconductor element light sources, each of the light sources comprising a cathode and an anode, said arrangements forming a plurality of light source branches, each of the branches comprising an anode, a cathode and a plurality of serially mounted light sources, the cathode of the branch being formed by the cathode of a light source, said cathode being located at one end of the branch, the anode of the branch being formed by the anode of a light source, said anode being located at the other end of the branch,
each light source of any given light source arrangement being of a same type, the type of the light sources in any given light source arrangement being distinct from the type of the light sources in any given other light source arrangement, such that each type of light source is designed to contribute to a distinct regulatory luminous function,
two power supply lines, each power supply line connecting the anodes of the respective branches of one light source arrangement;
a power supply control unit (140, 240) having a plurality of terminals, each terminal being connected to the cathodes of light source branches of a light source group, wherein each light source group comprises a semiconductor element light source branch of each type;
a control unit, which, based on a lighting instruction received for one of said regulatory light functions, generates a control signal, which causes one of the supply lines which connects the anodes of the branches of the corresponding arrangement of light sources to be provided with electricity at the exclusion of other supply lines of the luminous device.

Semiconductor element light sources are often mounted in branches, i.e. in a plurality of serially connected light sources, preferentially in a single string comprising no light sources mounted in parallel, as such parallel-mounted light sources represent a cost and may provide poor homogeneity regarding of colour and brightness. Branches may also include other components such as resistors, but, for the sake of energy efficiency, it is preferred that they do not.
In the invention, only light sources of a same type are mounted in branches in a same arrangement. However, as the light sources of a given arrangements are purposed to provide light specifically for contributing to a given regulatory luminous function, the light sources of another arrangement are of a different type, allowing to provide light for contributing to a distinct regulatory luminous function.
A plurality of branches is advantageous as it allows for animations of the luminous device, for instance. Specifically, when the supply lines are provided in electricity by battery power regulated through a step-down converter, such as a Buck converter, it is advantageous that the branches consist in serial assemblies of two or three light sources. Indeed, this avoids flickering when the battery voltage is transiently low, for instance at the vehicle start-up. Branches comprising higher numbers of serially connected light sources may be used. A non-step-down type of converter may accordingly be used, It is usually preferred that all branches have a similar number of serially connected light sources.
It is to be understood that, when a supply line is provided electricity at the exclusion of the other supply lines, any other supply line in the luminous device is not powered, which means that the branches of the corresponding arrangement are not powered. In other words, only one of the supply lines is powered at a given time. This is a requirement for the use of current-sink-type power supply control units.
Preferably, the power supply control unit can implement said control unit and comprises an input terminal for receiving lighting instructions on a motor vehicle data bus and a control terminal connected to a circuit for selectively interrupting the power supply to each of the two supply lines.
The control unit can preferably be separate from the power supply control unit.
Preferably, the control unit can be connected to a selector circuit for connecting a motor vehicle power source selectively to one of the supply lines.
Preferably, the control unit can be configured to selectively alternate the power supply between the two supply lines.
Preferably, a first type of semiconductor element light source can be designed to emit amber-coloured light, and a second type of semiconductor element light source can be designed to emit turquoise-coloured light.
In accordance with a second aspect of the invention, a method for supplying power to two arrangements of semiconductor element light sources of a luminous device for a motor vehicle according to one aspect of the invention is proposed. The method is remarkable in that it comprises the following steps:

the control unit of the luminous device receives a switching command for a regulated luminous function;
the control unit generates a control signal following receipt of said lighting instruction, the control signal causing the supply line corresponding to said regulation light function to be provided with electricity at the exclusion of other supply lines.

Preferably, the generated control signal can cause the two supply lines to be supplied with electricity exclusively on an alternating basis, at a predetermined alternating frequency.
The alternating frequency can preferably be at least 200 Hz.
The light perceived by the alternating power supply between the two types of semiconductor element light sources can preferably be white in colour.
Using the measures proposed by the present invention, it becomes possible to realize a luminous device luminous device and to propose a method of supplying a plurality of different types of light sources distributed in two arrangements, by means of a single control unit. According to preferred embodiments of the invention, several arrangements of light sources of different types, each type of light source being designed to emit different colours of light, are connected to a single control unit. A control unit, which is either a dedicated module or integrated into the control device, is used to selectively power one of the light source arrangement to the exclusion of the others. Compared with existing solutions, this approach makes it possible to reduce the number of printed circuits and control devices used, while at the same time achieving a plurality of regulatory luminous functions by means of the different types of light source. It is also possible to alternate the exclusive supply of two arrangements of light source, so that the light perceived by a human being will be different from the one and other colour emitted by two types of light source, according to the principle of additive synthesis. Depending on the choice of colours, two arrangements of light source can therefore use a single control unit, and generate light beams of at least three different colours, the colour emitted being dependent on the lighting ratio between the arrangements of light sources corresponding to the two types of light source over time.
Further features and advantages of the present invention will be better understood with the aid of the description of the examples and drawings among which :

Fig. 1 schematically shows a device in accordance with a preferred embodiment of the invention;
Fig. 2 schematically shows a device in accordance with a preferred embodiment of the invention.

Unless specifically indicated to the contrary, technical features described in detail for a given embodiment may be combined with technical features described in the context of other embodiments described by way of example and in a non-limiting manner. Similar reference numbers will be used to describe similar concepts across different embodiments of the invention. For example, references 100 and 200 refer to two embodiments of a luminous device according to the invention.
The illustration in Fig. 1 shows a light device 100 for a motor vehicle according to a preferred embodiment, which is based on a first architecture. The light device comprises a first type of light source 110 shown in white and a second type of semiconductor element light source 120 shown hatched. These are preferably LEDs. Each type of LED preferably emits a light beam with a specific wavelength: it may be two white lights at different temperatures, one white and one amber colour, or one blue colour. While the white colour may be associated with a regulatory function as a daytime running light or position light, the amber or yellow colour may be associated with a regulatory function as a direction indicator or warning light. As such, it appears the two different types are suited to several regulatory luminous functions. A turquoise colour can be associated with an autonomous mode indicator function.
As shown in Figure 1, light sources of a given type 110, 120 are preferably connected in series on a branch. In the example shown in the figure, each branch comprises two light sources of the same type, but other pluralities are conceivable without going beyond the scope of the present invention. Each branch comprises an anode corresponding to the anode of the first light-emitting diode in the series circuit, and a cathode corresponding to the cathode of the last light-emitting diode in the series circuit, viewed from top to bottom. The number of branches per type of light source is illustrated by way of example, without limiting the invention to any particular number of branches. Preferably, there are as many branches of the first type of light source as of the second.
A first electrical connection or supply arm 112 connects the anodes of the arms of the first type of light source 110. A second supply line 122 connects the anodes of the branches of the second type of light source 120. Each branch is connected to a voltage source V1, V2. This may be the same voltage source Vbat, supplied by a battery internal to the motor vehicle.
The light device 100 also comprises a power supply control unit 140 having a plurality of connection terminals 142. Each terminal is connected to the cathodes of light source branches 110, 120 of a light source group 130. A light source group comprises a branch of semiconductor element light sources of each type 110 and 120 respectively. In the example shown in Figure 1, a group 130 comprises two neighbouring or adjacent branches whose cathodes are connected to the same terminal 142 of the linear current regulator 140.
The control unit 140 also includes a terminal for receiving data from an internal motor vehicle data bus, such as a Controller Area Network (CAN) bus. In this way, the control unit is configured to receive a lighting instruction 160 in a CAN data packet. Following decoding by means of a data processing unit internal to the control unit, the latter generates a control signal 170 from an output port. The control signal causes either of the first 112 or the second 122 supply lines to be interrupted or, on the contrary, connected to a source of electrical voltage, in accordance with the instruction 160 received. If the command is for a position light, for example, the supply line with white LEDs is supplied with electricity. If, on the other hand, the instruction is intended for a direction indicator, the supply line comprising amber LEDs is supplied with electricity. The power supply to the two supply lines 112, 122 is controlled on a mutually exclusive basis. The control signal 170 controls two switches 113, 123 to realize the described functionality. The control unit 140 common to both LED types thus realizes a control unit 150 for both LED types.
In a particular embodiment which is not illustrated, the signal 170 is generated based on a single output port of the control unit, such that the signal driving the two switches 113, 123 is generated by generating the signal to control the first switch 113 from the output port, and inverting it to obtain a signal for controlling the second switch 123.
Figure 2 shows a light device 200 for a motor vehicle according to a preferred embodiment, which is based on a second architecture. The light device comprises a first type of light source 210 shown in white and a second type of semiconductor element light source 220 shown hatched.
As shown in Figure 2, light sources of a given type 210, 220 are preferably connected in series on a branch, as in the case of Figure 1.
A first electrical connection or supply line 212 connects the anodes of the branches of the first arrangement of light source 210. A second supply line 222 connects the anodes of the branches of the second type of light source 220. Each branch is connected to the same voltage source Vbat, supplied by a battery inside the motor vehicle, by means of an electronic selection circuit comprising two switches 213, 223, preferably implemented by transistors.
The light device 200 also comprises a power supply control unit 240 having a plurality of connection terminals 242. Each terminal is connected to the cathodes of light source branches 210, 220 of a light source group 230. A light source group comprises a branch of semiconductor element light sources of each type 210 and 220 respectively. In the example shown in Figure 2, a group 230 comprises two neighbouring or adjacent branches whose cathodes are connected to the same terminal 242 of the linear current regulator 240.
The luminous device 200 comprises a control unit 250, which is by way of non-limiting example implemented by a microcontroller element programmed to control the state of switches 213, 223 as a function of a lighting instruction 260 received by a central control unit of the motor vehicle. The control signal 270 generated by the control unit causes either the first 212 or the second 222 supply line to be interrupted or, on the contrary, connected to the electrical voltage source Vbat, in accordance with the instruction 160 received. If the command is for a position light, for example, the supply line with white LEDs is supplied with electricity. If, on the other hand, the instruction is for a direction indicator, the supply line with the amber LEDs is supplied with power. The power supply to the two supply lines 212, 222 is controlled on a mutually exclusive basis. The control signal 270 controls two switches 213, 223 to realize the described functionality. Instead of managing the exclusive power supply by programming the control unit, the selection circuit can also provide an electronic circuit which ensures the power supply of one or the other branch, or which gives power supply priority to one of the branches, when both branches would be connected to the electrical voltage source. Such arrangements are within the reach of the person skilled in the art.
Irrespective of the architecture used, in a preferred embodiment of the invention, the first type of semiconductor element light sources 110, 210 is capable of emitting amber-coloured light and the second type of semiconductor element light sources 120, 220 is capable of emitting turquoise-coloured light. Light-emitting diodes with corresponding characteristics are known per se in the art. Individually powered, each of the 112,212 and 122,222 power supply lines allow providing light contributing to a regulatory function of direction indicator (amber) and autonomous mode indicator (turquoise). Both regulatory functions require a luminous flux of similar luminous intensity.
The human visual system is unable to discern repeated light switching at frequencies above around 200 Hz. Above this frequency, the brain interprets an alternating light intensity (and absence thereof) as a continuous average light intensity. In the context of the device according to the invention, this principle is used to realize the generation of a luminous flux of a third colour by additive synthesis. By alternating the power supply between the first supply line 112, 212 and the second supply line 122, 222 at a frequency of 200 Hz or more, the individual amber and blue luminous fluxes become indistinguishable, and an additive mixture of the two colours, resulting in white light, is perceived by an observer.
Using an alternating 170, 270 control signal, the proposed device can therefore be used to emit a white luminous flux of similar luminous intensity to that of the direction indicator and the autonomous driving indicator. It can, for example, perform the regulatory position light function by mixing amber and blue light streams. In particular, the colour mix can be influenced by the cyclic ratio between the duration of supply of one branch (colour) relative to the other over one cycle of the periodic control 170. In this way, a PWM (pulse width modulation) signal, and its inverse, can be used to control switches 113, 213 and 123, 223 respectively, to achieve additive colour synthesis. The PWM signal can be generated either by the control unit 150, 250 following receipt of a corresponding instruction 160, 260. Alternatively, a dedicated electronic circuit can be used to generate a PWM signal from an applied voltage level. The skilled person will be able to apply the invention's teaching to devices comprising more than two types of light sources each mounted in branches, corresponding to supply lines, as long as an exclusive control scheme is provided.
The scope of protection is determined by the claims.

Claims

Luminous device (100, 200) for a motor vehicle comprising:
- two arrangements of semiconductor element light sources (110, 120; 210, 220), each of the light sources comprising a cathode and an anode, said arrangements forming a plurality of light source branches, each of the branches comprising an anode, a cathode and a plurality of serially mounted light sources, the cathode of the branch being formed by the cathode of a light source, said cathode being located at one end of the branch, the anode of the branch being formed by the anode of a light source, said anode being located at the other end of the branch,

- each light source of any given light source arrangement being of a same type, the type of the light sources in any given light source arrangement being distinct from the type of the light sources in any given other light source arrangement, such that each type of light source is designed to contribute to a distinct regulatory luminous function,

- two power supply lines (112, 122; 212, 222), each power supply line connecting the anodes of the respective branches of one light source arrangement (110, 120; 210, 220);

- a power supply control unit (140, 240) having a plurality of terminals (142, 242), each terminal being connected to the cathodes of light source branches (110, 120; 210, 220) of a light source group (130, 230), wherein each light source group comprises a semiconductor element light source branch of each type (110, 120; 210, 220);

- a control unit (150, 250), which, on the basis of an lighting instruction (160, 260) received for one of said regulatory light functions, generates a control signal (170, 270) which causes one of the supply lines (112, 122; 212, 222) which connects the anodes of the branches of the corresponding arrangement of light sources (110, 120; 210, 220) to be supplied with electricity at the exclusion of other supply lines.
Luminous device (100) according to the preceding claims, characterized in that the power supply control unit (140) implements said control unit (150) and comprises an input terminal for receiving lighting instructions (160) on a motor vehicle data bus and a control terminal connected to a circuit for selectively interrupting (113, 123) the power supply to each of the two supply lines (112, 122).
Luminous device (200) according to claim 1, characterized in that the control unit (250) is separate from the power supply control unit (240).
Luminous device according to the preceding claim, characterized in that the control unit (250) is connected to a selection circuit (213, 223) for connecting a motor vehicle power source selectively to one of the supply lines (212, 222).
Luminous device (100, 200) according to one of the preceding claims, characterized in that the control unit (150, 250) is configured to selectively alternate the power supply between the two supply lines (122, 222).
Light device (100, 200) according to one of the preceding claims, characterized in that a first type of semiconductor element light sources (110, 210) is designed to emit amber-coloured light and a second type of semiconductor element light sources (120, 220) is designed to emit blue-coloured light.
A method of supplying power to two types of semiconductor element light sources of a luminous device (100, 200) for a motor vehicle according to one of the preceding claims, the method comprising the following steps:
- -at the level of the control unit (150, 250) of the luminous device, receive an lighting instruction (160, 260) for a regulation luminous function;

- -at the control unit (150, 250), generate a control signal (170, 2709) following receipt of said lighting instruction, the control signal causing the supply line corresponding to said regulation light function to be supplied exclusively with electricity.
A power supply method according to the preceding claim, characterized in that the control signal generated causes the two supply lines to be supplied with electricity exclusively in alternation, at a predetermined alternation frequency.
Power supply method according to the preceding claim, characterized in that the alternating frequency is at least 200 Hz.
Power supply method according to the preceding claim, characterized in that the luminous device (100, 200) conforms to claim 6, and in that the light perceived by the alternation of power supply between the two types of semiconductor element light sources has a white colour.