WO2024256311A1 - Device for controlling multiple current-controlled leds - Google Patents

Abstract

The invention relates to a device for controlling at least two light-emitting diodes (LED_i), the device comprising, for each light-emitting diode: - an input intended to receive a control signal (SC_i) for the light-emitting diode (LED_i); and - current-control means (ACC_i) for the light-emitting diode. Each input intended to receive a control signal (SC_i) is connected, via a diode (D_i), to the same voltage-regulating device (REG). The voltage-regulating device (REG) comprises an output provided with a switch (SW) controlled by a signal fed to the voltage-regulating device. The current-control means (ACC_i) of a light-emitting diode (LED_i) are powered, on the one hand, by a control signal (SC_i) received over the corresponding input to turn on/turn off the light-emitting diode (LED_i) and, on the other hand, by the voltage output by the voltage regulator (REG).

Description

Description

Device for controlling multiple current-controlled LEDs

[0001] The present disclosure relates to a device for controlling multiple LEDs, i.e. light emitting diodes, controlled by current.

Technical field

[0002] The present disclosure relates to the field of electrical circuits for motor vehicles and more particularly a circuit for controlling lighting comprising several light sources.

[0003] The present disclosure may find an application for lighting on the exterior of a vehicle, such as at the level of a door handle. Such lighting then makes it possible to illuminate the interior of a door handle at night to make it easier for a user to grip. Lights of different colors may, for example, be used when opening and closing the vehicle.

Previous technique

[0004] In a door handle, there is little space available to accommodate several LEDs and their control electronics. To limit the number of components, it is possible to choose to use LEDs that are not current-controlled. This then leads to a significant fluctuation in the light intensity delivered by each LED.

[0005] It is therefore preferable to have a current control of each LED to have a better control of the light intensity. To then also control the light intensity, it is known to have a PWM type modulation (from the English Pulse Width Modulation or MLI in French for Pulse Width Modulation). We then use a signal of constant frequency and variable duty cycle.

Summary

[0006] The present disclosure therefore aims to provide a device for controlling lighting with several LEDs with current control of each LED having a limited size so as to be able to be integrated into a restricted space such as the inside of a vehicle door handle. This device will preferably allow control of a PWM functionality to best control the light intensity delivered. Advantageously, the delays in switching on and/or switching off each LED will be as short as possible.

[0007] A device is proposed for controlling at least two light-emitting diodes comprising for each light-emitting diode:

- an input intended to receive a control signal for said light-emitting diode, and

- current control means for said light-emitting diode.

[0008] According to the present disclosure, each input intended to receive a control signal is connected via a respective diode to an input of the same regulating device. voltage, the voltage regulating device comprises an output provided with a switch controlled by a signal supplying said voltage regulating device at the input, and the current control means of a light-emitting diode are supplied, on the one hand, by the control signal received on the corresponding input of the control device, for switching on/off said light-emitting diode and, on the other hand, by the voltage at the output of the voltage regulator.

[0009] A diabolo structure is therefore proposed here. On one side of a voltage regulation device, the power supply signals of the light sources are grouped together and on the other side of this voltage regulation device, a redistribution is carried out to the light sources.

[0010] The features set forth in the following paragraphs may, optionally, be implemented, independently of one another or in combination with one another:

[0011] - the switch is a MOSFET type transistor;

[0012] - the voltage regulating device has a capacitance at its input, arranged between the input of said voltage regulating device and the respective diodes;

[0013] - the voltage regulating device has a capacitance at its output, upstream of the switch;

[0014] - the control device further comprises for each light-emitting diode a PWM type signal generator, i.e. pulse width modulation, connected to the corresponding input intended to receive a control signal.

[0015] According to another aspect, there is provided a motor vehicle door handle lighting system, comprising a sensor, for example a presence sensor, a control device and at least one light-emitting diode, said system comprising at least two light-emitting diodes, and the control device being a device as described above. In such a lighting system, the light-emitting diodes emit, for example, lights of different colors.

[0016] According to another aspect, there is provided a motor vehicle comprising a lighting system as described above.

Brief description of the drawings

[0017] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the attached drawings, in which:

Fig. 1

[0018] [Fig. 1] shows a block diagram of a control system according to the present disclosure for a three-LED lighting system. [0019] [Fig. 2] shows an electronic diagram of a control system according to the present disclosure.

Fig. 3

[0020] [Fig. 3] shows a schematic diagram of operation corresponding to the control system of Fig. 2.

Fig. 4

[0021] [Fig. 4] schematically shows a vehicle provided with a door handle lighting system with a control system according to the present disclosure.

Description of the embodiments

[0022] Reference is now made to Figure 1. This figure is a block diagram illustrating a control system for three light-emitting diodes LED_1, LED_2 and LED_3. Each diode is here associated with its own activation and current control device ACC_1, ACC_2 and ACC_3. It is known to those skilled in the art how to carry out current control in a light-emitting diode to control the light intensity of the diode. Such a control device is illustrated for example in Figure 2 and will be described later with reference to this figure.

[0023] Each light-emitting diode LED_i is controlled by a control signal SC_i, i.e. here SC_1, SC_2 and SC_3. This signal is for example controlled by an electronic control unit, known as ECU, as a function of events such as in particular signals received from sensors: presence sensors, brightness sensors, etc.

[0024] Each of the signals SC_i is applied to an input E_i: this signal is then transmitted directly to an assembly formed by the corresponding light-emitting diode LED_i and to its current control device ACC_i. Each signal SC_i is also transmitted after passing through a diode D_i to a voltage regulation device REG common (or unique) to the entire control system.

[0025] The voltage regulation device REG has a single input which receives a superposition of the signals SC_i after their respective passage through the diodes D_i. Thus, if one of the signals SC_i is active, i.e. it corresponds to a command to turn on a light-emitting diode LED_i, then the corresponding diode D_i is conductive, and an active signal is applied to the input of the voltage regulation device REG. On the other hand, if no signal SC_i is active, i.e. the commands for each light-emitting diode LED_i correspond to turning off the corresponding light-emitting diode, then no signal is applied to the input of the voltage regulation device REG.

[0026] It is noted in FIG. 1 that the voltage regulation device REG has a single output providing a regulated voltage VRef, said output being associated with a switch SW. The latter is controlled by the input signal of the voltage regulation device REG, the switch SW being open when the input signal of the voltage regulation device REG is inactive (no input signal) and the switch SW being closed when the input signal of the voltage regulation device REG is active. When the switch SW is closed, the regulated voltage VRef is applied to each set formed by a corresponding light-emitting diode LED_i and its corresponding current control device ACC_i. The voltage regulation device REG thus provides a common reference voltage Vref, or regulated voltage, to each LED driver stage, in particular each current control device ACC_i. This ensures precise current regulation for each of the LED_i.

[0027] It is noted that a capacitor C1 is connected to the input of the voltage regulation device REG. This capacitor is sized such that the voltage regulation device REG is supplied without interruption, in particular when it receives an alternating signal as input.

[0028] We also note the presence of a capacitor C2 connected to the output of the voltage regulation device REG. This capacitor C2 is sized according to the light-emitting diodes to form an energy reserve.

[0029] This control system thus makes it possible, with a single voltage regulator device REG, to efficiently control a plurality of light-emitting diodes LED_1, LED_2, ..., LED_n. Conventionally, a control signal SC_i is generated for each light-emitting diode to control these light-emitting diodes independently of each other, to be able to light one or two or more without acting on the others for example. The superposition of the control signals, after each control signal has passed through a diode, is injected into the input of the voltage regulator device REG. This new control signal corresponding to the superposition of the control signals is used to control the switch SW. When said new control signal is active (at least one of the diodes is conducting, indicating that at least one of the signals SC_i is active, i.e. it corresponds to a command to turn on a light-emitting diode LED_i), the switch SW is closed and the voltage regulation of the voltage regulation device REG is available for all the light-emitting diodes LED_i. These being furthermore directly controlled by a control signal SC_i specific to them, each light-emitting diode is then driven individually and operates with both voltage and current control. When all the signals SC_i are inactive, i.e. they all correspond to a command to turn off a light-emitting diode LED_i, it is not necessary to supply the regulated voltage VRef to any of said light-emitting diodes LED_i. In this case, it is proposed in the invention to disconnect the voltage regulator from the light-emitting diodes LED_i during this time interval, so as to avoid unnecessarily emptying, in the light-emitting diodes LED_i, an energy reserve stored in the capacitor C1 (and where applicable C2). This momentary disconnection is carried out by means of the switch SW controlled by the new control signal as defined above. This avoids unnecessarily spending energy stored in the capacitor 01 (and where applicable 02). This energy makes it possible to continue to supply current to the voltage regulator device REG thanks to the reserve of the capacitors 01 and where applicable 02. When the control signal is active again, the voltage regulator device REG does not have an ignition delay because it is already in operation. Such a delay ignition would distort the expected brightness, especially for low duty cycle pulse width modulations.

[0030] In summary, the structure of Figure 1 is a "diabolo" structure in which on one side the sources of activation of light-emitting diodes are grouped and on the other side the regulated signals are distributed to said diodes, a voltage regulator being at the center of the diabolo.

[0031] In Figure 2, an equivalent diagram illustrates in more detail a control system operating according to the principle illustrated in Figure 1.

[0032] In this figure on the left, we notice a power supply AL_1 for a first light-emitting diode LED_1. This power supply comprises a diode in series with a resistor as well as two capacitors. Only the power supply AL_1 is illustrated in this figure 2, but such a power supply is provided for each light-emitting diode LED_i of the system i varying from 1 to n, where n is a “reasonable” number of diodes to be used here. We will most often have n=2, 3 or 4 for a lighting application, in particular for lighting a motor vehicle door handle, but n can of course be greater than 4. In figure 2, three inputs have been shown to indicate that there can be several inputs.

[0033] Here we find diodes D_i with i varying from 1 to n. In the diagram of Figure 2 we find an additional diode D_0 arranged between the diodes D_i connected in parallel and the voltage regulation device REG. This diode D_0 has a non-return function and ensures that all the current from the inputs E_i goes into the voltage regulation device REG.

[0034] At the output of the voltage regulation device REG, the switch SW is represented by a MOSFET type transistor. It is controlled by the signal corresponding to the superposition of the control signals applied to the inputs E_i after passing through the diodes D_i. This component allows rapid activation and rapid deactivation of each light-emitting diode LED_i.

[0035] When the switch (MOSFET transistor) is switched (switch closed, therefore conducting) the voltage regulation operated by the voltage regulation device REG cooperates with each current control device ACC_i which ensures both the activation and the current control for the corresponding light-emitting diode LED_i. Just as a single power supply AL_1 is illustrated in FIG. 2, a single current control device ACC_1 is illustrated but there are in the system as many current control devices ACC_i as there are light-emitting diodes (i.e. n). In a manner known to those skilled in the art, the current regulation in the light-emitting diode LED_1 (respectively LED_i) is ensured by an assembly comprising in the basic form illustrated here a transistor (NPN) associated with a diode and two resistors. This assembly is given as a non-limiting illustrative example and other assemblies, for example without a diode, could also provide current regulation in a light-emitting diode of the present device.

[0036] While Figure 2 illustrates in more detail the components used to implement the present disclosure, Figure 3 illustrates the functions provided within a control system according to the present disclosure. To make the connection between the two figures, three frames are shown. in each of figures 2 and 3. A first frame F1 corresponds to the control of multiple light-emitting diodes. A second frame F2 corresponds to the activation and deactivation of the light-emitting diodes while a third frame F3 concerns the current regulation of the light-emitting diodes.

[0037] Figure 3 shows three light-emitting diodes, but as in Figure 2, the person skilled in the art will understand that the functional diagram applies to n light-emitting diodes, with n >=2.

[0038] First of all (outside the frames F1, F2 and F3) there is a power supply AL_i with i varying from 1 to n. This power supply preferably provides, for each light-emitting diode, a PWM type control signal, i.e. pulse width modulation. Thus, each control signal is composed of an alternation of a short duration high signal and a long duration low signal thanks to this pulse width modulation.

[0039] In the F1 frame, an “OR” function is applied to the control signals from the AL_i power supplies. This function is performed electronically by the D_i diodes. With this function, if only one signal is active then the “response”, or resulting signal, is active. The response is inactive only if all the input signals are inactive.

[0040] The output signal of the “OR” function, on the one hand, is applied to the input of the voltage regulation device REG and, on the other hand, controls the switch SW (frame F2) which allows rapid activation and rapid deactivation of the light-emitting diodes LED_i.

[0041] When the switch SW is closed, the regulation voltage VRef of the regulation voltage device REG cooperates with the current control devices ACC_i to ensure that the light-emitting diodes deliver the desired light intensity.

[0042] As mentioned, such a control device is more particularly intended for a lighting device in the automotive field, for exterior lighting of the vehicle, such as for example a door handle. FIG. 4 very schematically illustrates a vehicle 10 which comprises at least one sensor 11 (for example brightness sensor, remote control signal receiver, etc.) associated with an electronic controller 13, or electronic control unit (ECU). Within this electronic controller 13, control signals SC_i are generated. These are for example PWM type signals. These signals are transmitted to the control system described above arranged in a housing 12 integrating in particular the power supplies AL_i, the voltage regulation device REG and the switch SW. At the output of the housing 12, there are the light-emitting diodes LED_i and their current control devices ACC_i which are integrated for example in a door handle of the vehicle 10.

[0043] The sensor(s) 11 allow(s) to control the lighting under certain predefined conditions. The use of a brightness sensor can for example be used to avoid switching on the lighting device in broad daylight. A remote control receiver can be used to control the desired type of lighting: depending on the button used on the remote control, the light can be of one color or another, in progressive lighting, in flashing mode, etc. The sensor 11 can also be a capacitive presence sensor that detects for example the approach of a user, or more precisely of his hand. Of course, as suggested, several sensors can be used and the controlled lighting will be done according to the information received by the multiple sensors.

[0044] The control system described above makes it possible to control several light-emitting diodes (at least two, or even more than three) independently of each other. The proposed structure allows for a reduced size, which makes it possible to use multiple lighting in a restricted volume and in particular in a door handle with a length of approximately 10 cm, a few centimeters in height and a small thickness.

[0045] The control system of at least two light sources (LED or light-emitting diode) comprises a single voltage regulation device, common to all the light-emitting diodes. A control signal specific to each light source passes through a diode and the signals obtained are grouped at the input of the voltage regulation device. The diodes make it possible to supply current to the voltage regulation device when at least one of the control signals is not at zero. The switch at the output of the voltage regulation device is controlled by the input signal of the voltage regulation device.

[0046] In the case of a PWM (i.e. pulse width modulation) type control signal, said signal is composed of a short-duration alternating high signal and a long-duration low signal. In the preferred embodiment with a capacitance (capacitor) at the input of the voltage regulation device, said device is supplied without interruption even when it receives an alternating signal.

[0047] The embodiment with a MOSFET transistor type switch is advantageous because the presence of this MOSFET transistor makes it possible to disconnect the current control means of the light-emitting diodes from the voltage regulator when the control signal goes to the low state (during the pulse width modulation). The proposed structure advantageously makes it possible to no longer draw current from the voltage regulator. The latter can then continue to operate thanks to the reserve of capacitors C1 and C2. When the input voltage of the pulse width modulator rises again in the following cycle, the voltage regulator does not have a turn-on delay because it is already operating. Such a turn-on delay would distort the expected brightness, particularly for pulse width modulations with a low duty cycle.

[0048] It is noted that the response time of the diodes is generally very fast (less than 50 ns for example (i.e. 5 10EXP-8 s)) compared to a pulse width modulation period (of the order of a millisecond, i.e. 1*10EXP-3 s). The impact of this response time on the modulation is therefore really marginal.

This disclosure is not limited to the examples of embodiment and applications described above, only as non-limiting examples, but it encompasses all the variants that a person skilled in the art may envisage within the framework of the protection sought.

Claims

Claims [Claim 1] Device for controlling at least two light-emitting diodes (LED_i) comprising for each light-emitting diode: - an input intended to receive a control signal (SCJ) for said light-emitting diode (LEDJ), and - current control means (ACC_i) for said light-emitting diode, characterized in that: - each input intended to receive a control signal (SCJ) is connected via a respective diode (DJ) to an input of the same voltage regulation device (REG), the regulation device (REG) thus being configured to receive as input a signal corresponding to the superposition of the respective control signals (SCJ) of the at least two light-emitting diodes (LEDJ) after passing through the diodes (DJ), - the voltage regulating device (REG) has a capacitor (C1) at its input, arranged between the input of said voltage regulating device (REG) and the respective diodes (DJ), so that the voltage regulating device (REG) is supplied without interruption, - the voltage regulating device (REG) comprises an output equipped with a switch (SW) controlled by a signal supplying said voltage regulating device at the input and corresponding to the superposition of the respective control signals (SCJ) after passing through the diodes (DJ), and - the current control means (ACCJ) of a light-emitting diode (LEDJ) are supplied, on the one hand, by the control signal (SCJ) received on the corresponding input of the control device, for switching on/off said light-emitting diode (LEDJ), and, on the other hand, by a voltage at the output of the voltage regulator (REG) and the switch (SW). [Claim 2] Control device according to claim 1, characterized in that the switch (SW) is a MOSFET type transistor. [Claim 3] Control device according to claim 1 or 2, characterized in that the voltage regulating device (REG) has a capacitor (C2) at its output, upstream of the switch (SW). [Claim 4] Control device according to one of claims 1 to 3, characterized in that it further comprises, for each light-emitting diode (LEDJ), a PWM type signal generator, i.e. pulse width modulation, connected to the corresponding input intended to receive a control signal (SCJ). [Claim 5] Motor vehicle door handle lighting system, comprising a sensor (11), a control device and at least one light-emitting diode (LEDJ), characterized in that it comprises at least two light-emitting diodes, and in that the control device is a device according to one of claims 1 to 4. [Claim 6] Handle lighting system according to claim 5, characterized in that the light-emitting diodes (LEDJ) emit lights of different colors. [Claim 7] Motor vehicle, characterized in that it comprises a lighting system according to one of claims 5 or 6.