EP4355032A1

EP4355032A1 - Automotive luminous device

Info

Publication number: EP4355032A1
Application number: EP22201466.4A
Authority: EP
Inventors: Miguel Angel CANTUDO FRANCO
Original assignee: Valeo Vision SAS
Current assignee: Valeo Vision SAS
Priority date: 2022-10-13
Filing date: 2022-10-13
Publication date: 2024-04-17

Abstract

The invention provides an automotive luminous device (10) for an automotive vehicle (100). The luminous device (10) comprises a timer circuit (1) configured to receive an activation signal of a luminous function and configured to provide a first output signal during a predetermined time from the reception of the activation signal and then a second output signal different from the first output signal. It also comprises a selection circuit (3) configured to receive the output signals from the timer circuit, in such a way that the selection circuit has a first impedance value when receiving the first output signal and has a second impedance value different from the first impedance value when receiving the second output signal. Finally, it comprises a group of solid-state light sources (2) configured to perform the luminous function and a driver (4) comprising an input configured to receive the impedance value of the selection circuit and also configured to control the operation of the solid-state light sources as a function of the received impedance value.

Description

TECHNICAL FIELD

This invention is related to the field of automotive luminous devices which are controlled to provide luminous (signalling and/or lighting) functionalities.

STATE OF THE ART

Automotive luminous devices are designed to perform different functionalities. To do so, the luminous device comprises different lighting modules, each of them being in charge of one of the luminous functions.
These luminous functions are often provided by an arrangement of solid-state light sources. These types of light sources have proven to be efficient and powerful enough to fulfil the regulations, but have some issues with temperature.
Further, the manufacturers' requirements are in constant evolution. In some scenarios, a temporary luminous pattern in a specific luminous function, which in a top tier version is carried out by microcontrollers, is also desired in low tier versions. Since these versions are cheaper, luminous devices must be cheaper as well, and a suitable component to save costs is microcontroller.
But in these cases, the achievement of a specific temporary pattern without using microcontrollers is not easy. In particular, such a function may have to observe software development standards such as ASIL, which require extensive validation processes. The software-based functions may therefore create a hurdle to timely and cost-efficient project management.
A solution for this problem is therefore sought.

DESCRIPTION OF THE INVENTION

The invention provides a solution for achieving a temporary pattern in the brake lamp by means of an automotive luminous device for an automotive vehicle, the luminous device comprising

a timer circuit configured to receive an activation signal of a luminous function and configured to provide a first output signal during a predetermined time from the reception of the activation signal and then a second output signal different from the first output signal;
a selection circuit configured to receive the output signals from the timer circuit, in such a way that the selection circuit has a first impedance value when receiving the first output signal and has a second impedance value different from the first impedance value when receiving the second output signal;
a group of solid-state light sources configured to perform the luminous function when being powered; and
a driver comprising an input configured to measure the impedance value of the selection circuit and also configured to control the operation of the solid-state light sources as a function of the measured impedance value.

With this circuit, a particular temporary pattern of activating a luminous function with a first current and, after a time has lapsed, a different current is achieved without active components. Hence, this may be used in low tier models, with a cheap and reliable outcome.
The selection circuit is therefore intended to allow the driver to measure an impedance value which is representative of the light source characteristic and is relevant for supplying the light source with current. In particular, this value characterises the light source's efficiency, which is defined by a light flux per unit of current.
The term "solid state" refers to light emitted by solid-state electroluminescence, which uses semiconductors to convert electricity into light. Compared to incandescent lighting, solid state lighting creates visible light with reduced heat generation and less energy dissipation. The typically small mass of a solid-state electronic luminous device provides for greater resistance to shock and vibration compared to brittle glass tubes/bulbs and long, thin filament wires. They also eliminate filament evaporation, potentially increasing the life span of the illumination device. Some examples of these types of lighting comprise semiconductor light-emitting diodes (LEDs), organic light-emitting diodes (OLED), or polymer light-emitting diodes (PLED) as sources of illumination rather than electrical filaments, plasma or gas.
In some particular embodiments, the luminous function is a stop lamp function. A stop lamp function may indeed benefit from being activated with a first intensity value during a time lapse and then return to a standard intensity value. In particular, better perception of the tail function may be achieved when the first value is higher, and the second value is lower.
In some particular embodiments, the group of solid-state light sources comprises at least three solid-state light sources. This is a suitable number of light sources, so that the function may be performed reliably when the driver is powered directly from a typical car battery, with a 9-16V output voltage, which is typically lower on vehicle start-up.
In some particular embodiments, the second output signal is zero.
In these circuits, there is no need for the selection circuit to receive a second signal different from zero: when the first signal value is received, the extra current value is provided, and when no signal is received from the timer circuit (but the activation signal is still received in the driver), the light sources are fed with the standard current value.
In some particular embodiments, the selection circuit comprises at least a first portion, a second portion and a switch configured to control the connection of the first portion with the rest of the selection circuit.
A switch is a cheap and simple element, which may be fed by the timer circuit for an easy and simple variation of the impedance of the selection circuit.
Preferentially, the driver is adapted for measuring a resistance on the input connected to the selection circuit, and the impedance provided on this input by the selection circuit is a resistance value with negligible reactance.
In some particular embodiments, the first portion comprises at least a first resistor and the second portion comprises at least a second resistor.
Resistors are a simple and easy way to define a specific impedance value, the variation of which may be easily identified by the driver.
In some particular embodiments, the first portion and the second portion are connected in series, and the switch is configured to control a bypass branch connected between the input and the output of the first portion. In more particular embodiments, the switch comprises a n-type MOSFET.
With this example, the driver may see either the two resistances in series (when the bypass is open) or just the second resistance (when the bypass is closed). The bypass is controlled by a bypass controller. N-type MOSFETs are cheap elements which activate when receiving the signal from the timer, then opening the bypass in the first predetermined time, so that the two resistances are seen and then the driver feeds the light sources with the high-value current.
In some particular embodiments, the first portion and the second portion are connected in parallel, and the switch is configured to open or close the branch of the first portion. In more particular embodiments, the switch comprises a p-type MOSFET or a BJT.
With this example, the driver may see either the two resistances in parallel (when the parallel branch is closed) or just the second resistance (when the parallel branch is open). The parallel branch is controlled by a p-type MOSFET or a BJT, which are cheap elements which activate when receiving the signal from the timer, then closing the parallel branch in the first predetermined time, so that the two resistances are seen and then the driver feeds the light sources with the high-value current.
In some particular embodiments, the timer circuit comprises a RC filter. The values of the resistor and the capacitor will be chosen depending on the time range of the first output value. When the activation signal is received, the capacitor of the RC filter starts charging, so that a first voltage output value is sent by the timer circuit. When the capacitor is completely charged, no output signal is sent.
In some particular embodiments, the timer circuit comprises a timer clock. The timer clock is designed to cut the output value when the predetermined time is reached, so this is an easy control.
In some particular embodiments, the timer circuit comprises a thermistor. The thermistor would measure the temperature of the LEDs. An easy relation of the evolution of temperature with time may be established, so that the predetermined time corresponds to a specific temperature. By configuring the circuit to stop sending the output value when reaching this temperature, this solution will be successfully achieved.
Unless otherwise defined, all terms (including technical and scientific terms) used herein are to be interpreted as is customary in the art. It will be further understood that terms in common usage should also be interpreted as is customary in the relevant art and not in an idealised or overly formal sense unless expressly so defined herein.
In this text, the term "comprises" and its derivations (such as "comprising", etc.) should not be understood in an excluding sense, that is, these terms should not be interpreted as excluding the possibility that what is described and defined may include further elements, steps, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

To complete the description and in order to provide for a better understanding of the invention, a set of drawings is provided. Said drawings form an integral part of the description and illustrate an embodiment of the invention, which should not be interpreted as restricting the scope of the invention, but just as an example of how the invention can be carried out. The drawings comprise the following figures:

Figure 1 shows a general electric scheme of an automotive luminous device according to the invention.
Figure 2 show a scheme alternative of another automotive luminous device according to the invention.
Figure 3 shows an automotive luminous device according to the invention installed in an automotive vehicle.

Elements of the example embodiments are consistently denoted by the same reference numerals throughout the drawings and detailed description where appropriate:

1: Timer circuit
2: LED
3: Selection circuit
4: Driver
5: First impedance
6: Second impedance
7: MOSFET
8: Driver output
10: Automotive luminous device
100: Automotive vehicle

DETAILED DESCRIPTION OF THE INVENTION

The example embodiments are described in sufficient detail to enable those of ordinary skill in the art to embody and implement the systems and processes herein described. It is important to understand that embodiments can be provided in many alternate forms and should not be construed as limited to the examples set forth herein.
Accordingly, while embodiment can be modified in various ways and take on various alternative forms, specific embodiments thereof are shown in the drawings and described in detail below as examples. There is no intent to limit to the particular forms disclosed. On the contrary, all modifications, equivalents, and alternatives falling within the scope of the appended claims should be included. Elements of the example embodiments are consistently denoted by the same reference numerals throughout the drawings and detailed description where appropriate.
Figure 1 shows a general electric scheme of a portion of an automotive luminous device according to the invention. This portion comprises a timer circuit 1 and a selection circuit 3, which are connected to a driver which controls a group of LEDs 2.
The timer circuit 1 is configured to receive an activation signal of the brake lamp function from the body car module. When this activation signal is received, the timer circuit emits a first output signal. This first output signal is only emitted during a predetermined interval (for example, 3 seconds). Then, the timer circuit stops the signal and sends no output voltage value.
The output signal of the timer circuit is received by the selection circuit 3. Hence, when the activation signal is received by the timer circuit 1, the selection circuit 3 receives firstly a first signal from the timer circuit during, e.g., 3 seconds, and then this signal is ceased.
The impedance value of this selection circuit varies depending on the signal which is received from the timer circuit 1. In this particular embodiment, this is achieved in the following way.
The selection circuit 3 comprises two impedances 5, 6. When the signal received by the selection circuit 3 from the timer circuit is the first output signal, the total impedance value of the selection circuit is the one equivalent to the two impedances. But when the signal received by the selection circuit from the timer circuit ceases, the total impedance value of the selection circuit is the one equivalent to only one of the two impedances.
The driver 4 has an output 8 which sees the impedance value of the selection circuit 3. When the impedance value is the one corresponding to the two impedances, the driver feeds the group of LEDs with a first current, and when the impedance value is the one corresponding to only one of the impedances, the driver feeds the group of LEDs 2 with a second current.
Hence, during, e.g., the first three seconds since the brake signal is sent to the lighting device, the LEDs 2 which are in charge of the braking function receive a first current, which is more intense, so the light emitted by these LEDs 2 is more intense. Then, after these, e.g. 3 seconds, the current is the standard current for the brake lamp function, which is lower than the first current.
This temporary pattern is achieved without the use of a microcontroller or active elements.
Figures 2 and 3 show the selection circuits of two different examples of a luminous device according to the invention.
Figure 2 shows the two impedances 5, 6 in parallel and a p-type MOSFET 7 which is connected to the branch of one of the impedances. When the timer sends the first output value, the MOSFET 7 activates and closes the branch of one of the impedances, so that the driver measures the two impedances in parallel and feeds the LEDs with the maximum current.
After the predetermined time range has lapsed, the timer circuit stops sending any output value so the p-type MOSFET opens the circuit, so that the driver only measures one of the impedances, and feeds the LEDs with the standard current.
When the activation signal ceases, the driver does not receive any current, so no current is sent to the LEDs.
Figure 3 shows the two impedances 5, 6 in series and a n-type MOSFET 7 which is controls a bypass branch which bypasses one of the impedances. When the timer sends the first output value, the MOSFET activates and opens the branch of one of the impedances, so that the driver measures the two impedances in series and feeds the LEDs with the maximum current.
After the predetermined time range has lapsed, the timer circuit stops sending any output value so the n-type MOSFET closes the bypass branch, so that the driver only measures the non-bypassed impedance, and feeds the LEDs with the standard current.
When the activation signal ceases, the driver does not receive any current, so no current is sent to the LEDs.
Concerning the timer circuit, there are different solutions to obtain a first output voltage value during a predetermined time and then a second output voltage value, the second output voltage being preferentially zero, that is to say a null voltage.
A first option would involve the use of an RC filter. The values of the resistor and the capacitor will be chosen depending on the time range of the first output value. When the activation signal is received, the capacitor of the RC filter starts charging, so that a first voltage output value is sent by the timer circuit. When the capacitor is completely charged, no output signal is sent. The RC filter is a very cost efficient alternative, with a precision largely depending on that of its components. Moreover, this implies that it is sensitive to temperature variations.
A second option would involve the use of a timer clock. The timer clock is designed to change the output value when the predetermined time is reached. This is a more precise but more expensive solution.
Finally, a third option would involve the use of a thermistor. The thermistor may measure the temperature of the LEDs, or of the driver. An easy relation of the evolution of temperature with time may be established, so that the predetermined time corresponds to a specific temperature. By configuring the circuit to stop sending the output value when reaching this temperature, this solution will be successfully achieved. Such a solution may prevent repeated flashing of a brighter function in cases of repeated activation on a short time, as the thermistor's temperature remains high enough that the value displayed by the selection circuit remains .
A timer circuit may be obtained by combining sub-circuits such as the first and second options, or the second and third options, or the first and third options, for instance by combining the outputs of the sub circuits, for instance through a logic gate, for instance an OR gate or an AND gate, which may allow for combining their advantages.
Figure 4 shows an automotive luminous device 10 according to the invention installed in an automotive vehicle 100.
This automotive luminous device 10 controls the operation of a great amount of LEDs 2 without an overheating risk for the internal light driver. As a consequence, the performance of the LEDs 2 may be optimized without endangering the operation of the rest of the device.

Claims

Automotive luminous device (10) for an automotive vehicle (100), the luminous device (10) comprising
a timer circuit (1) configured to receive an activation signal of a luminous function and configured to provide a first output signal during a predetermined time from the reception of the activation signal and then a second output signal different from the first output signal;

a selection circuit (3) configured to receive the output signals from the timer circuit, in such a way that the selection circuit has a first impedance value when receiving the first output signal and has a second impedance value different from the first impedance value when receiving the second output signal;

a group of solid-state light sources (2) configured to perform the luminous function when being powered; and

a driver (4) comprising an input configured to measure the impedance value of the selection circuit and also configured to control the operation of the solid-state light sources as a function of the measured impedance value.
Automotive luminous device according to claim 1, wherein the luminous function is a stop lamp function.
Automotive luminous device according to any of the preceding claims, wherein the group of solid-state light sources (2) comprises at least three solid-state light sources.
Automotive luminous device according to any of the preceding claims, wherein the second output signal is zero.
Automotive luminous device according to claim 4, wherein the selection circuit (3) comprises at least a first portion, a second portion and a switch (7) configured to control the connection of the first portion with the rest of the selection circuit.
Automotive luminous device according to claim 5, wherein the first portion (5) comprises at least a first resistor and the second portion comprises at least a second resistor (6).
Automotive luminous device according to claim 6, wherein the first portion and the second portion are connected in series, and the switch (7) is configured to control a bypass branch connected between the input and the output of the first portion.
Automotive luminous device according to claim 7, wherein the switch comprises a n-type MOSFET.
Automotive luminous device according to claim 6, wherein the first portion and the second portion are connected in parallel, and the switch (7) is configured to open or close the branch of the first portion.
Automotive luminous device according to claim 9, wherein the switch (7) comprises a p-type MOSFET or a BJT.
Automotive luminous device according to any of the preceding claims, wherein the timer circuit (1) comprises a RC filter.
Automotive luminous device according to any of the preceding claims, wherein the timer circuit (1) comprises a timer clock.
Automotive luminous device according to any of the preceding claims, wherein the timer circuit (1) comprises a thermistor.