LIGHTING CIRCUIT FOR AUTOMOTIVE LIGHTING DEVICE AND AUTOMOTIVE LIGHTING DEVICE

Abstract

LIGHTING CIRCUIT FOR AUTOMOTIVE LIGHTING DEVICE AND AUTOMOTIVE LIGHTING DEVICE The invention provides an automotive lighting device (10) comprising a first lighting group (1) and a second lighting group (2) configured to emit light. The device (10) further comprises a lighting driver (4) and an optical element (9) configured to receive the light emitted by the first lighting group and the second lighting group (1, 2) and project it outside the lighting device (10). The lighting driver (4) comprises a power input (3). The lighting driver (4) comprises a dynamic boost circuit (14) comprising a boost unit (8) and a capacitor branch (11), where the boost unit (8) is connected between the power input (3) and the capacitor branch (11) and is configured to provide a voltage output when receiving electrical power from the power input (3).The lighting driver (4) further comprises a first step-down converter (12) and a second step-down converter (13), the first step-down converter (12) being arranged between the dynamic boost circuit and the first power output (6), and the second step-down converter (13) being arranged between the dynamic boost circuit and the second power output (7). The lighting driver (4) is configured to increase the output voltage of the boost unit (8) upon receiving a start event signal from the vehicle control unit. Abstract figure: Fig. 2.

Description

Title of the invention: LIGHTING CIRCUIT FOR AUTOMOTIVE LIGHTING DEVICE AND DEVICE BRIGHT AUTOMOBILE Technical field

[0001] The present invention belongs to the field of lighting devices installed in motor vehicles, and more specifically to the electronic assemblies used in these motor vehicle lighting devices. STATE OF THE ART

[0002] During engine startup, the battery voltage drops and some functions may be disabled depending on the intensity of the startup pulse.

[0003] Customers today accept that lighting functions may turn off during the start-up process in difficult conditions.

[0004] However, even if this is not critical, it is at least quite unsightly (and can further lead to safety issues) if a light element goes out. DESCRIPTION OF THE INVENTION

[0005] The present invention provides a solution to these problems by means of an automotive lighting device comprising: a first lighting group configured to emit light to contribute to a first lighting function, a second lighting group configured to emit light to contribute to a second lighting function, the first lighting group and the second lighting group comprising at least one solid-state light source; a lighting driver comprising a power input, a data input, a first power output and a second power output, wherein the power input is for receiving a power signal, the data input is configured to receive data from a control unit of the vehicle, the first power output is connected to provide electrical power to the first lighting group and the second power output is connected to provide electrical power to the second lighting group, Or : the lighting driver comprises a dynamic boost circuit comprising a boost unit and a capacitor branch, wherein the boost unit is connected between the power input and the capacitor branch and is configured to provide a voltage output when receiving electrical power from the power input; the lighting driver further comprises a first step-down converter and a second step-down converter, the first step-down converter being disposed between the dynamic boost circuit and the first power output, and the second step-down converter being disposed between the dynamic boost circuit and the second power output; and the lighting driver is configured to increase the output voltage of the boost unit upon receiving a start event signal from the vehicle control unit.

[0006] A boost unit or step-up converter is a DC-DC converter that increases voltage, while decreasing current, from its input (power supply, usually power from the vehicle's battery) to its output (load).

[0007] A step-down converter or buck converter is a DC-DC converter that decreases the voltage, while increasing the current, from its input (usually the output of the booster unit) to its output (connected to the driver's power output to power the corresponding lighting group). Step-down converters offer much higher energy efficiency than linear regulators as DC-DC converters and are preferred in automotive lighting devices.

[0008] Each driver has an optimal operating point, which differs from the operating point of the light sources and the voltage level provided by the vehicle's battery. The use of step-up and step-down converters is a common practice to adapt the current to the different elements. The present invention is aware of this practice, but it introduces the fact that the driver can increase the output voltage of the supercharger unit when receiving a start event signal from the vehicle's Body Control Module, BCM, by means of the data input. As a result, the capacitor is able to store much more energy and prevent the lighting functions from turning off in the event of a start event under difficult conditions.

[0009] The data input provides the driver with useful information and, among other things, a start event indicator, which is used in the present invention to increase the boost voltage level to minimize the dangerous effect of the start event under difficult conditions.

[0010] In some particular embodiments, the first lighting function corresponds to at least one of the following functions: daytime running lights, DRL, low beam headlights, headlights, direction indicator lights, front or rear position lights and high beam headlights. In some particular embodiments, the second lighting function corresponds to at least one of the following functions: daytime running lights, DRL, low beam headlights, headlights, direction indicator lights, front or rear position lights and high beam headlights. daytime running lights, DRL, low beam, headlights, direction indicator lights, front or rear position lights and high beam.

[0011] Lighting or signaling functions that require lower voltage will benefit more from this invention, because the standard voltage will be lower and the voltage increase in the dynamic boost circuit will be higher.

[0012] In some particular embodiments, the lighting driver is configured to increase the voltage of the booster unit to at least 50 V, preferably at least 59 V, preferably 60 V.

[0013] Although current automotive applications only require this boost stage to increase the voltage up to 30 V, a higher voltage is preferable because more energy can be stored in the capacitor, minimizing the effects of the start event under harsh conditions.

[0014] In certain particular embodiments, the capacitor has a capacitance greater than 50 pF, in particular greater than 80 pF, and in particular greater than or equal to 100 pF.

[0015] In the particular case of 100 pF capacitors, which are generally used in automotive circuits, the stored energy can be multiplied by 4, because the voltage is doubled compared to standard use. Not all of this energy will be used, but the present invention makes it possible to increase the duration of the corresponding lighting function.

[0016] In certain particular embodiments, the dynamic boost circuit, the first step-down converter and the second step-down converter are arranged in the same electronic substrate.

[0017] The electronic substrate is also called a printed circuit board, PCB. In some particular embodiments, the electronic substrate is a rigid electronic substrate. The substrate can also be made flexible. A rigid substrate should be understood in the sense that a person skilled in the art would interpret it. A person skilled in the art knows the difference between a rigid substrate and a flexible substrate. Although any material is "flexible" in the sense that it has a certain stress-strain curve, a substrate that does not deform under its own weight when held by one of its ends is considered rigid, while a substrate that undergoes substantial deformation when held by one of its ends is considered flexible. In any event, printed circuit board manufacturers offer a "flexible" model and a "rigid" model, and a person skilled in the art knows the difference between the two.

[0018] In a second aspect of the invention, the invention relates to a luminous device au- car including: a lighting circuit according to the first aspect of the invention; an optical element designed to receive light emitted by the first lighting group and by the second lighting group and project it outside the lighting device.

[0019] In certain particular embodiments, the optical element is a light guide or a reflector.

[0020] An optical element is an element that has certain optical properties to receive a beam of light and emit it in a certain direction and / or in a certain shape, as a person skilled in automotive lighting would interpret it without any additional burden. Reflectors, collimators, light guides, projection lenses, etc., or the combination thereof are some examples of such optical elements that are useful for transforming the beams of light emitted by the light source into a light pattern acceptable for the functionality chosen for the lighting device.

[0021] In certain particular embodiments, the semiconductor light sources are light-emitting diodes.

[0022] The term "solid-state" refers to light emitted by electroluminescence from a semiconductor, which uses semiconductors to convert electricity into light. Compared to incandescent lighting, solid-state lighting creates visible light with reduced heat generation and less power dissipation. The generally low mass of a solid-state electronic lighting device gives it greater resistance to shock and vibration compared to fragile glass tubes / bulbs and long, thin filament wires. They also eliminate filament evaporation, potentially increasing the lifespan of the lighting device.Some examples of these types of lighting include semiconductor light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), or polymer light-emitting diodes (PLEDs) as lighting sources rather than electric filaments, plasma, or gas. These light sources are particularly advantageous because they provide the lighting properties required for automotive regulations with high efficiency and reliability.

[0023] In some particular embodiments, the data input is connected to a bus communication interface, such as a local area network or a controller area network (CAN) or a clock extension peripheral interface.

[0024] CAN buses are commonly used in automotive lighting devices and allow a two-way exchange of information between the body control module (BCM) and the driver.

[0025] Unless otherwise defined, all terms (including technical and scientific terms) used herein shall be interpreted as is customary in the art. It will be further understood that terms in common usage shall also be interpreted in the manner customary in the relevant art and not in an idealized or excessively formal sense, unless expressly so defined herein.

[0026] In this text, the term "includes" and its derivatives (such as "comprising", etc.) should not be understood in an exclusive sense, that is to say, these terms should not be interpreted as excluding the possibility that what is described and defined may include other elements, steps, etc. Brief description of the drawings

[0027] To complete the description and in order to provide a better understanding of the invention, a set of drawings is provided. Said drawings are an integral part of the description and illustrate an embodiment of the invention, which should not be interpreted as limiting the scope of the invention, but only as an example of embodiment of the invention. The drawings include the following figures:

[0028] [Fig. 1] represents a lighting device according to the invention, which is installed in a motor vehicle.

[0029] [Fig.2] represents an electronic diagram of some of the elements contained in the light device shown in [Fig.l].

[0030] [Fig.3] shows some data associated with the improvement presented in the invention.

[0031] In this document, the following reference numbers have been used: 1 First group of LEDs 2 Second group of LEDs 3 Power input 4 Lighting driver 5 Data Entry 6 Power output for the first lighting group 7 Power output for the second lighting group 8 Supercharger unit 9 Light Guide 10 Lighthouse 11 Capacitor branch 12 Step-down converter for the first lighting group 13 Step-down converter for the second lighting group 14 Dynamic supercharging circuit 100 Motor vehicle DETAILED DESCRIPTION OF THE INVENTION

[0032] The exemplary embodiments are described in sufficient detail to enable persons of ordinary skill in the art to make and implement the systems and processes described herein. It is important to understand that the embodiments may be provided in many other forms and should not be construed as limited to the examples presented herein.

[0033] Accordingly, although the embodiment may be modified in various ways and take various alternative forms, specific embodiments thereof are shown in the drawings and described in detail below by way of example. There is no intention to limit the scope of protection of the particular forms disclosed. Rather, all modifications, equivalents, and variations falling within the scope of the appended claims are to be included. Elements of the exemplary embodiments are consistently designated by the same reference numerals throughout the drawings and the detailed description where appropriate.

[0034] [Fig. 1] represents an embodiment of a light device 10 according to the invention, installed in a motor vehicle 100.

[0035] This light device 10 is a headlight, and it is configured to provide the usual functions, i.e. daytime running lights, DRL, low beams, high beams, turn signal lights, front position lights and direction indicator lights.

[0036] These functions are provided by light sources contained in the lighting device. The light emitted by these light sources is received by a light guide 9 and projected outside the headlights 10.

[0037] [Fig.2] represents an electronic diagram of some of the elements contained in the light device shown in [Fig.l].

[0038] As can be seen in this figure, there is a first group of LEDs 1 configured to emit light in order to contribute to obtaining the DRL function. This first group contains a plurality of LEDs.

[0039] There is also a second group of LEDs 2, which are configured to emit light to contribute to achieving the direction indicator function. This second group also contains several LEDs.

[0040] A lighting driver 4 is designed to provide a controlled power supply to these two groups LED 1 and LED 2. This lighting driver 4 comprises a power input 3, a data input 5 and two power outputs 6, 7.

[0041] The power input 3 is intended to receive a power signal from the vehicle battery. This power signal generally has a voltage of 12 V and is used to provide the power necessary for the LEDs to perform their respective functions.

[0042] The data input 5 is configured to receive data from a body control module, BCM, of the vehicle 100 via a CAN bus, thereby enabling a bidirectional exchange of information between these two entities, including instructions, signals and diagnostic information. In the context of the present invention, it is of interest that the body control module, BCM, can send to the driver an indicator concerning the start event when the user starts the vehicle.

[0043] The power supply outputs 6, 7 are intended to provide the electrical power supply to the first and second groups of light sources.

[0044] To do this, there are intermediate elements between the power supply input 3 and the power supply outputs 6, 7 to prepare this power supply.

[0045] First, there is a dynamic boost circuit 14. This circuit comprises a boost unit 8 and a capacitor branch 11. The boost unit 8 is arranged between the power input 3 and the capacitor branch 11. This boost unit 8 is configured to increase the voltage from the level provided by the vehicle battery (as previously stated, 12 V) to an amount that will be optimal to meet the needs of the LED clusters. In one embodiment, this voltage may be, for example, 30 V. This optimal boost voltage is intended to optimize the overall efficiency of the driver in normal mode.

[0046] A capacitor branch 11 is connected between the output of the booster unit 8 and ground. This capacitor has a capacitance value selected based on the power requirements of the first LED group 1 and the second LED group 2 in order to provide optimal power to the booster unit 8. In one embodiment, the capacitance value may be, for example, 100 pF and may store energy and ensure continuous operation of the lighting groups.

[0047] Finally, two step-down converters 12, 13 are arranged between the dynamic boost circuit 14 and the power outputs 6, 7. A step-down converter is a DC-DC converter that decreases the voltage and increases the current. The first step-down converter 12 is placed between the dynamic boost circuit 14 and the first power output 6, and is intended to prepare the voltage for powering the first lighting group 1. The second step-down converter 13 is placed between the dynamic boost circuit 14 and the second power output 7, and is intended to prepare the voltage to power the second lighting group 2. Thus, a correct voltage can be delivered to each of the lighting groups 1 and 2.

[0048] When the lighting driver 4 receives the start event indicator from the vehicle's BCM 100 via the data input 5 such as a CAN bus, it provides instructions to the boost unit 8 to increase the voltage level from 30 V to 60 V. The boost unit 8 together with the capacitor network 11 of the dynamic boost circuit 14 provide the necessary voltage increase. Thus, the dangerous effect of the start event in difficult conditions, such as bad weather, is minimized.

[0049] Thanks to this increase, the energy stored by the capacitor is 4 times greater than in the standard case, due to the fact that the voltage is doubled compared to normal use. Not all of this energy will be used, but the present invention makes it possible to increase the duration of the corresponding lighting function.

[0050] [Fig. 3] represents data associated with the improvement presented in the invention. In particular, it shows the power received by the first group of LEDs in two different responses to a standardized start pulse: the first response (represented by the dotted line) corresponds to the case where the invention is not applied and the boost group only increases the voltage up to 30 V when the start event is to take place. The second response (represented by the solid line) is the response associated with a system according to the present invention, where the driver commands the boost unit to increase the voltage up to 60 V when the start event is to take place. In the first case, the first group is powered for 6 ms before the cut-off, while in the second case, the first group is powered for 15 ms before the cut-off.Therefore, by implementing this invention, we are able to maintain the power supply for a longer duration.

[0051] Further, in one embodiment, when the start pulse is low and the vehicle is operating under normal conditions, the present invention enables powering both the first lighting group and the second lighting group, thereby maintaining the operational state of the LEDs at the time of the start pulse.

Claims

Claims

1. A lighting circuit for an automotive lighting device (10) comprising: a first lighting group (1) configured to emit light to contribute to a first lighting function, a second lighting group (2) configured to emit light to contribute to a second lighting function, the first lighting group (1) and the second lighting group (2) comprising at least one solid-state light source; a lighting driver (4) comprising a power input (3), a data input (5), a first power output (6) and a second power output (7), wherein the power input (3) is for receiving a power signal, the data input (5) is configured to receive data from a control unit of the vehicle, the first power output (6) is connected to provide electrical power to the first lighting group (1) and the second power output (7) is connected to provide electrical power to the second lighting group (2), wherein: the lighting driver (4) comprises a dynamic boost circuit (14) comprising a boost unit (8) and a capacitor branch (11), wherein the boost unit (8) is connected between the power input (3) and the capacitor branch (11) and is configured to provide a voltage output when receiving electrical power from the power input (3); the lighting driver (4) further comprises a first step-down converter (12) and a second step-down converter (13), wherein the first step-down converter (12) is placed between the dynamic boost circuit and the first power supply output (6), and the second step-down converter (13) is placed between the dynamic boost circuit and the second power supply output (7); and the lighting driver (4) is configured to increase the output voltage of the supercharger unit (8) upon receiving a start event signal from the vehicle control unit.

2. A lighting circuit according to claim 1, wherein the first lighting function corresponds to at least one of the following functions: daytime running lights, DRL, low beam, headlights, direction indicator lights, front or rear position lights and high beam.

3. A lighting circuit according to any preceding claim, wherein the second lighting function corresponds to at least one of the following functions: daytime running lights, DRL, low beam, headlights, direction indicator lights, front or rear position lights and high beam.

4. A lighting circuit according to any preceding claim, wherein the lighting driver is configured to increase the voltage of the booster unit to at least 50 V, preferably at least 59 V, preferably 60 V.

5. Lighting circuit according to any one of the preceding claims, wherein the capacitor has a capacitance greater than 50 pF, in particular greater than 80 pF, in particular greater than or equal to 100 pF.

6. A lighting circuit according to any preceding claim, wherein the dynamic boost circuit (14), the first step-down converter (12) and the second step-down converter (13) are arranged in the same electronic substrate.

7. An automotive lighting device comprising a lighting circuit according to any preceding claim; an optical element (9) adapted to receive light emitted by the first lighting group (1) and by the second lighting group (2) and project it outside the lighting device (10).

8. An automotive lighting device according to claim 7, wherein the optical element is a light guide or a reflector.

9. An automotive lighting device (10) according to any one of claims 7 or 8, wherein the solid-state light sources are light-emitting diodes.

10. An automotive lighting device (10) according to any one of claims 7 to 9, wherein the data input is connected to a bus communication interface, such as a local area network, a controller network or a clock extension peripheral interface.

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