FR2989648A1 - Lighting system for car, has lighting unit used as day running light, and another lighting unit used as night light, where control unit controls transistor to close or open power supply circuit of latter lighting unit - Google Patents

Abstract

The system has a lighting unit (2) used as a day running light, and another lighting unit (3) used as a night light, where a power supply circuit (200) of the former lighting unit is connected to a power supply circuit (300) of the latter lighting unit. A controller (10) supplies a pulse width modulation (PWM) signal to the former lighting unit. A comparator (40) compares a value of a magnitude representative of a duty cycle of the PWM signal with a predetermined value. A control unit (41) controls a transistor (5) to close or open the power supply circuit of the latter lighting unit. The transistor is a bipolar transistor or a field effect transistor. An independent claim is also included for a method for controlling a power supply circuit of a lighting unit.

Description

The present invention relates more particularly to a vehicle lighting system comprising first lighting means able to emit a first light power value to be used as daytime running lights. and capable of emitting a second light power value for use as position lights, a supply circuit for said first lighting means, and a computer comprising a supply output to which said supply circuit is connected said first lighting means. Said computer is able to generate pulse width modulated signals, called PWM signals, on said power supply output, including a PWM signal having a first duty cycle ratio for supplying the first lighting means with daylight and a PWM signal having a second duty cycle ratio, lower than said first duty cycle ratio, for powering the first position light lighting means. The invention also relates to a vehicle equipped with such a lighting system and a power control method of such a lighting system.

In a motor vehicle, daytime running lights, also called Day Running Light (DRL), are generally white light lighting devices located at the front. They usually turn on automatically when the vehicle is moving forward to increase vehicle visibility under daylight conditions. These daytime running lights are technically distinct from low beam. Indeed, low beam are originally designed to see and not to be seen. The position lights, also commonly referred to as "lanterns" or "night lights", are lights, usually white at the front and red at the rear, which allow the vehicle to indicate its presence and width to other users. , at night and when visibility conditions are bad. Generally, the light power of the position lights is of the order of five times less than the light power of the daytime running lights.

It is known from the state of the art a lighting system, as described in the introduction, whose lighting means can ensure not only the function of position lights, but also the function of daytime running lights. For this purpose, as illustrated in FIG. 1, the lighting system comprises on each side towards the front of the vehicle a set of LEDs 2 'that can be powered by a power supply circuit 200' connected to a power supply output of a calculator 10 'forming a control unit. Said computer is configured to allow, on the one hand, to supply each set of LEDs 2 'with a PWM signal (Pulse Width Modulation) which has a duty cycle of 100% in order to operate said set of LEDs in daylight and, on the other hand, supplying each set of LEDs 2 'with a PWM signal having a duty ratio of 10 to 25%, in order to operate said set of LEDs in position lights. In other words, the function differentiation of said illumination means is effected by using PWM signals of different duty cycle values: 100% to obtain the daytime running lights and 10 to 25% to obtain the position lights. In some countries, and in particular for the United States, it is requested to add for each of said lighting means which combine the functions of day lights and position lights, additional position lamps, also called "side marker", for the vehicle is better visible from the side. Indeed, the position lights, formed by the same means of lighting as those used to form the daytime running lights, are mostly visible from the front.

The present invention aims to allow the addition of additional position lights without having to use additional power supply output of the computer, in order to use standard computers and limit the cost of the corresponding lighting system. Another object of the present invention is to enable the daytime running lights to be operated without the addition of said additional parking lights. Some regulations prohibit the use of additional position lights when daytime running lights are on. For this purpose, the subject of the invention is a vehicle lighting system comprising: first lighting means able to emit a first light power value to be used as daytime running lights and able to emit a second light; light power value for use as position lights, - a supply circuit for said first lighting means, and - a computer comprising a power supply output to which said supply circuit of said first power supply means is connected. illumination, said computer being adapted to generate on said power output pulse width modulated signals, called PWM signals, including a PWM signal having a first duty cycle ratio for supplying the first lighting means to a light source. days and a PWM signal having a second duty cycle ratio, lower than said first duty ratio, to feed the first means of position lamp lighting, characterized in that said system also comprises: second lighting means adapted to be used as position lights, said system comprising: a supply circuit for said second lighting means which is connected to the supply circuit of said first lighting means, - interruption means for closing and opening said supply circuit which connects the second lighting means to the supply circuit of said first means of illumination; illumination, means for comparing the value of a quantity representative of the duty cycle of the signal of the PWM signal generated at the output of the computer, with respect to a predefined value, of the control means enabling, as a function of the result of said comparison, , controlling said interrupting means to close or open the supply circuit of the second lighting means.

Such a lighting system makes it possible to selectively light the daytime running lights and all of said position lights, that is to say those common with said daytime running lights formed by the first lighting means and the traffic lights. additional positions formed by the second lighting means, from a single power supply of the computer.

Indeed, the analysis of the duty cycle of the PWM signal which supplies the first lighting means makes it possible to detect the daylight or position light function which is activated at the level of the first lighting means, and thus to allow or not the supply of the second lighting means usable as additional position lights. The solution according to the invention makes it possible to keep a vehicle wiring architecture that is simple and without the need for an additional power output to power the additional position lights, which makes it possible to use standard calculators. In other words, thanks to such a trick of controlling the supply of the second lighting means from the available PWM signals, it is not necessary to add additional outputs to the standard computers that equip the vehicles. In particular, such a lighting system according to the invention makes it possible not to require a power supply circuit specific to the second lighting means that would be connected to a dedicated additional power supply of the computer.

It will be noted that the combined use of the interruption means and means for analyzing the PWM signal generated at the output of the computer, makes it possible for the additional position lamps not to be automatically switched on when the daytime running lights are. According to an advantageous characteristic of the invention, said control means are configured such that if the value of the quantity representative of the duty cycle of the PWM signal is greater than said predefined value, for example 50%, then said control means control by means of said interruption means, opening or maintaining the opening of the supply circuit of the second lighting means.

According to an advantageous characteristic of the invention, said control means are configured such that if the value of the quantity representative of said determined duty cycle is less than said predefined value, for example 50%, then said control means control, by by means of said interrupting means, the closing or the closed maintenance of the supply circuit of the second lighting means. Preferably, said predefined value is chosen to be between the value of the quantity representative of the duty cycle of the PWM signal used to supply the first illumination means in position light mode, and the value of the quantity representative of the signal duty cycle. PWM used to power the first lighting means in daylight mode. According to an advantageous characteristic of the invention, said interruption means comprise a relay or a bipolar or field-effect type transistor. According to an advantageous characteristic of the invention, said system comprises a capacitor arranged to store energy in the closed state of said power supply circuit of the second lighting means. The capacitor (or capacitance) makes it possible to smooth the pulses because of the low duty cycle of the PWM signal corresponding to the ignition of the second lighting means. According to an advantageous characteristic of the invention, said second lighting means comprise light-emitting diodes, called LEDs. The first lighting means may comprise one or more halogen type lamps and / or LEDs. According to an advantageous characteristic of the invention, said second lighting means comprise a number of LEDs less than the number of LEDs of said first lighting means. lighting means. The invention also relates to a vehicle comprising a lighting system provided with first lighting means able to emit a first light power value to be used as daytime running lights and able to emit a second light power value to be used as position lamps, said vehicle also comprising a supply circuit for said first lighting means, and a computer comprising a supply outlet to which said supply circuit of said first lighting means is connected, said computer being able to generate on said power output pulse width modulated signals, called PWM signals, including a PWM signal having a first duty cycle ratio for supplying the first lighting means in daylight and a signal PWM having a second duty cycle ratio, lower than said first duty cycle ratio, for powering the first illumination means in position lights, characterized in that said illumination system is as described above. According to an advantageous characteristic of the vehicle according to the invention, the second lighting means are positioned, preferably in a vehicle headlamp with the first lighting means, so as to be visible on one side of the vehicle. The invention also relates to a method for controlling the supply of first lighting means able to emit a first light power value to be used as daytime running lights and able to emit a second light power value to be used. as position lamps, and second illumination means adapted to be used as position lamps and whose supply circuit is connected to the supply circuit of the first illumination means, said method comprising a step supplying said first lighting means with a pulse width modulated signal, referred to as the PWM signal, for operating the first lighting means in daytime running lights or position lights, characterized in that said method comprises the following steps: - comparing the value of a quantity representative of the duty cycle of said PWM signal with a predefined value, - depending on the result of the comparison, control of the closing or opening of the supply circuit of said second lighting means.

The invention will be better understood on reading the following description of exemplary embodiments, with reference to the appended drawings in which: FIG. 1 is a view of a vehicle lighting system known from the state of the technical; FIG. 2 is a view of a vehicle lighting system according to the invention and according to a first embodiment of the interruption means; - Figure 3 is a view of a vehicle lighting system according to the invention and according to a second embodiment of the interruption means; - Figure 4 is a detailed view of an alternative embodiment of the second lighting means of a vehicle lighting system according to the invention; FIG. 5 is a view of a vehicle lighting system according to the invention in which the PWM signal discrimination means are of analog type; FIG. 6 is a view of a vehicle lighting system according to the invention in which the PWM signal discrimination means are of digital type; FIG. 7 is a view of a vehicle lighting system according to the invention in which the PWM signal discrimination means are of the programmable type.

Referring to the figures and as recalled above, the invention relates to a vehicle lighting system comprising first lighting means 2 adapted to be used as day lights and as position lights. The luminous power emitted in position lights is lower than that emitted in daytime running lights. Said first lighting means 2 are arranged in a projector, also called a headlight, in the front and on the left or right side of the vehicle. Said vehicle according to the invention also comprises other first lighting means (not shown), similar to said first lighting means 2, which are arranged in another projector located at the front and on the other side, right or left, of the vehicle. The description below of the lighting system according to the invention is made in connection with said first lighting means 2 located on one side of the vehicle, but also applies to the other first lighting means located on the side of the vehicle. other side of the vehicle. The lighting system also comprises second lighting means 3 adapted to be used as position lights. In the example illustrated in the figures, said first and second lighting means 2, 3 comprise light-emitting diodes, called LEDs. Said second lighting means 3 comprise a number of LEDs less than the number of LEDs of said first lighting means 2. The second lighting means 3 are located at the front of the vehicle on the same side as said first lighting means 2, and are preferably arranged in the projector which houses said first lighting means 2. As a variant, said second lighting means 3 may be located outside the projector which incorporates said first lighting means 2. Said lighting system illumination comprises a supply circuit 200 of said first lighting means 2 by a pulse width modulated signal, called the PWM signal. The power supply circuit 200 is connected to a power supply output of a computer 10. Said computer is in the form of an electronic and computer system which is configured to enable a PWM signal to be supplied to said power supply circuit 200. Said computer 10 is connected to the vehicle battery and is able to receive activation commands for daytime running lights and position lights. Said computer 10 can adapt the duty cycle of this PWM signal according to the desired operating mode of the second lighting means 3 to be activated. It can thus be provided that when the computer 10 receives a daytime running control, said computer 10 outputs a PWM signal having a duty cycle of 100%. Similarly, when the computer 10 receives an instruction of lighting of the position lights, said computer 10 outputs a PWM signal duty cycle of 10 to 25%, for example 25%. The lighting system also comprises a power supply circuit 300 which connects the second lighting means 3 to the supply circuit 200 of said first lighting means 2. Said supply circuit 30 is stitched onto the supply circuit 200 of the first lighting means 2.

Thus, in the example illustrated in FIG. 2, said second lighting means 3 are connected in parallel with the first lighting means. A transistor 5 is interposed between the supply circuit 200 of the first lighting means 2 and said second lighting means 3 to allow, as detailed below, to allow or not the power supply of the second lighting means. 3 by the supply circuit 200 of said first lighting means 2 as a function of the type of PWM signal which supplies said first lighting means 2. In the example illustrated in FIG. 2, said transistor is a bipolar transistor and in FIG. the example illustrated in FIG. 3, said transistor is a field effect transistor. In a variant, the transistor may be replaced by a relay (mechanical or static) whose control input is connected to the output of the control means 41, and whose two poles or connectors are connected to the supply circuit 200 of said first lighting means 2, and the other at the supply input of the second lighting means 3. Whatever the type of transistor used, the base or gate of the transistor is connected to the output of means discrimination 4 detailed below, and the collector, or drain, of the transistor is connected to the supply circuit 200 of said first lighting means 2. The emitter, or source, of the transistor is connected to the input of supplying second illumination means 3. Said discrimination means 4 comprise means 40 for comparing the value of a quantity representative of the duty cycle with a predefined value, and control means 41 making it possible, depending on the resistor further from said comparison, controlling said interrupting means 5 to close or open the supply circuit 300 which connects the second lighting means 3 to the supply circuit 200 of said first lighting means 2. In particular, said discrimination means 4 comprises an input 5 connected to the supply circuit 200 of said first lighting means 2 for determining said representative quantity of the duty cycle of the PWM signal. Said representative magnitude of the duty cycle may be a characteristic of the PWM signal such as the integrated voltage of said signal or the time value of the duty cycle of said signal as detailed below. Thus, the power supply output of the computer 10 used to power the first lighting means 2 via the power supply circuit 200 also makes it possible to supply the second lighting means 3 via the circuit 300 connected locally to the circuit 200 when transistor 5 is passing. The supply circuit 200 of the first lighting means 2 carries not only the energy supply of said first lighting means 2, but also information associated with this energy, which is analyzed to control or not the supply of said second lighting means 3. More precisely, the circuit 200 also transports the power supply of the second lighting means to the point on which the circuit 300 is locally located. It is therefore possible to realize the lighting system. lighting 3 according to the invention, without having to use additional output on the computer 10, which allows the use of standard computers. Said discrimination means 4 make it possible to control the on state or not of the transistor 5 and thus to allow or interrupt the passage of the supply current between the supply circuit 200 and said second lighting means 3 for lighting said second lighting means 3 when the first lighting means 2 are turned on in position light and for switching off said second lighting means 3 when the first lighting means 2 are lit in day lights. Thus, said first and second lighting means 3 can be powered by the same power supply output of the computer, while preventing the second lighting means 3 which form additional position lights are lit when the first lighting means 2 are lit on daylight.

In particular, said control means 41 are configured to perform the following conditional steps: if the value of the duty cycle of the PWM signal at the output of the computer is greater than, or possibly equal to, said predefined value, for example 50%, then said control means 41 control, through the transistor 5, opening or maintaining the opening of the power supply circuit 300 which connects the second lighting means 30 to the supply circuit 200 said first means of lighting 2; if the value of said determined duty cycle is less than said predefined value, for example 50%, then said control means 41 control, by means of the transistor 5, closing or maintaining closed said supply circuit 300. Said predefined value is chosen to be between the value of the duty cycle of the PWM signal used to supply the first illumination means 2 in position light mode, and the value of the duty cycle of the PWM signal used to power the first illumination means 2 in daylight mode. As a reminder, the value of the duty cycle of the PWM signal used to power the first lighting means 2 in position light mode is less than the value of the duty cycle of the PWM signal used to power the first lighting means 2 in the light mode. days. Thus, if the discrimination means 4 determine that the value of the duty cycle of the PWM signal which supplies the first lighting means 2 is less than, or possibly equal to, said predefined value, this implies that the first lighting means 2 are powered in position lamp mode.

The control means 41 of said discrimination means 4 then emit a signal at the base or gate of the transistor 5 which allows the passage of current between the collector, or drain, of the transistor 5 which is connected to the supply circuit 200 of said first means 2, and the transmitter, or source, which is connected to the supply input of the second lighting means 3. Advantageously, a capacitor C1 is positioned in parallel with said second lighting means 3. Said capacitor C1 is sized to store energy in the closed state of said power supply circuit 300 which connects the second lighting means 3 to the supply circuit 200 of said first lighting means 2. Said capacitor C1 is sized to store energy to smooth the supply current of the second lighting means 3 which receive energy from the supply circuit 200 only during the duty cycle ratio of the corresponding PWM signal (that is to say between 10 and 25% when the supply circuit 300 is closed). The capacitor C1 makes it possible to filter and smooth the chopped current transmitted by the computer 10 to the second lighting means 3, which makes it possible, in order to obtain a given light flux, to use LEDs of smaller power than those that we should use if we did not have a capacitor. In particular, the PWM signal consists of pulses, called T_on, which carry the energy, and pulses, called T_off, which do not convey energy. The partial absorption of the tips T_on by the capacitor makes it possible to use LEDs which accept lower voltage peaks.

In the case where the transistor 5 is a field effect transistor (see FIG. 3), a diode 50 is interposed between the transistor 5 and the capacitor to act as a rectifying diode, in order to prevent the capacitor current from recirculated by the field effect transistor.

According to a particular embodiment illustrated in FIG. 4, in order to ensure a substantially constant light flux of the second lighting means 3, said second lighting means 3 are equipped with a DC / DC converter 30 which makes it possible to transforming the energy stored in the capacitor C1 into a substantially constant current. As detailed below, the discrimination means 4 can be realized in different ways.

According to a first embodiment illustrated in FIG. 5, the discrimination means 4 are made in analog manner by using an integrating filter 42 and a comparator 43 in series with the integrating filter 42. The integrating filter 42 receives as input a voltage V1 corresponding to the output voltage of the computer 10, and delivers a voltage Vs41 representative of the duty cycle of the PWM signal which supplies said first lighting means 2. The comparator 43 compares the voltage Vs41 with a reference voltage Vref representative of said predefined value and delivers a voltage Vs4 representative of the result of this comparison. When the comparator determines that the duty cycle of the PWM signal is less than the predefined value, the voltage Vs4 makes it possible to control the on state of the transistor 5. According to a second embodiment illustrated in FIG. 6, the discrimination means 4 are made digitally with means 44 for shaping the PWM signal, means 45 for generating a standard signal, and means 46 for shaping a control signal of the transistor 5 according to the comparison of said shaped PWM signal and the signal with the generated standard signal. This solution is robust and does not require complex components of low tolerance (that is to say accurate). According to a third embodiment illustrated in FIG. 7, it is also possible to compare the value (or time) of the duty cycle with a standard value (or time) using means 47 for shaping the PWM signal and programmable logic or microprocessor 48. The advantage of this solution lies in the flexibility of design through the ability to modify the firmware without changing the physical structure of the system.

The present invention is not limited to the embodiments described and shown, but the skilled person will be able to make any variant within his mind.

Claims (10)

REVENDICATIONS1. Vehicle lighting system comprising: - first lighting means (2) able to emit a first light power value to be used as daytime running lights and able to emit a second light power value for use in as position lights, - a power supply circuit (200) of said first lighting means (2), and - a computer (10) comprising a power supply output to which said power supply circuit (200) is connected said first lighting means (2), said computer (10) being able to generate on said power output pulse width modulated signals, called PWM signals, including a PWM signal having a first duty cycle ratio for supplying the first lighting means (2) with daytime running lights and a PWM signal having a second duty cycle ratio, lower than said first duty cycle ratio, for supplying the first lighting means projection lamp (2), characterized in that said system also comprises: second lighting means (3) adapted to be used as position lamps, said system comprising: a power supply circuit ( 300) of said second lighting means (3) which is connected to the supply circuit (200) of said first lighting means (2), - interruption means (5) for closing and opening said circuit power supply unit (300) which connects the second lighting means (3) to the supply circuit (200) of said first lighting means (2), - means for comparing (40) the value of a magnitude representative of the duty cycle of the signal of the PWM signal generated at the output of the computer (10), with respect to a predefined value; - control means (41) enabling, according to the result of said comparison, controlling said interrupting means (5) to close or open the power supply circuit (300) of the d the second lighting means (3). 2. System according to claim 1, characterized in that said control means (41) are configured so that if the value of the magnitude representative of the duty cycle is greater than said predefined value, for example 50%, then said means by means of said interrupting means (5), the control means (41) control the opening or the maintenance of the opening of the supply circuit (300) of the second lighting means (3). 3. System according to claim 2, characterized in that said control means (41) are configured so that if the value of the quantity representative of said determined duty cycle is less than said predefined value, for example 50%, then said control means (41) control, by means of said interrupting means (5), the closed or the closed maintenance of the supply circuit (300) of the second lighting means (3). 4. System according to one of the preceding claims, characterized in that said interruption means (5) comprise a relay or a bipolar type transistor or field effect. 5. System according to one of the preceding claims, characterized in that said system comprises a capacitor (C1) arranged for storing energy in the closed state of said supply circuit (300) of the second lighting means. (3). 6. System according to one of the preceding claims, characterized in that said second lighting means (3) comprise light-emitting diodes, called LEDs. 7. System according to claim 6, characterized in that said second lighting means (3) comprise a number of LEDs less than less than the number of LEDs of said first lighting means (2). 8. Vehicle comprising a lighting system provided with first lighting means (2) able to emit a first light power value to be used as daytime running lights and able to emit a second light power value to be used as position lamps, said vehicle also comprising a power supply circuit (200) of said first lighting means (2), and a computer (10) comprising a supply output to which said supply circuit is connected (200) said first lighting means (2), said computer (10) being able to generate on said power output pulse width modulated signals, called PWM signals, including a PWM signal having a first rate of cyclic ratio for supplying the first lighting means (2) with daytime running lights and a PWM signal having a second duty cycle ratio, lower than said first duty cycle ratio, for food er the first lighting means (2) in position lights, characterized in that said lighting system is according to one of the preceding claims. 9. Vehicle according to claim 8, characterized in that the second lighting means (3) are positioned, preferably in a vehicle headlamp with the first lighting means (2), so as to be visible from a side of the vehicle. 10. Method for controlling the supply of first lighting means (2) able to emit a first light power value to be used as daytime running lights and able to emit a second light power value for use in as position lights, and second lighting means (3) adapted to be used as position lights and whose power supply circuit (300) is connected to the power supply circuit (200) of the first signaling means. lighting (2), said method comprising a step of supplying said first lighting means (2) with a pulse width modulated signal, referred to as a PWM signal, for operating the first lighting means (2) on the lights of days or lights position, characterized in that said method comprises the following steps: - comparison of the value of a magnitude representative of the duty cycle of said PWM signal with a predefined value, - depending on the r as a result of the comparison, controlling the closing or opening of the supply circuit (300) of said second lighting means (3).