Control device for multiple current-controlled LEDs

Abstract

A control device for at least two light-emitting diodes (LEDs) (LED_i) comprising, for each LED: - an input for receiving a control signal (SC_i) for said LED (LED_i), and - current control means (ACC_i) for said LED. Each input for receiving a control signal (SC_i) is connected via a diode (D_i) to the same voltage regulator (REG). The voltage regulator (REG) comprises an output equipped with a switch (SW) controlled by a signal supplying said voltage regulator at its input. The current control means (ACC_i) of an LED (LED_i) are powered, on the one hand, by a control signal (SC_i) received at the corresponding input for switching said LED (LED_i) on / off and, on the other hand, by the voltage (Vref) at the output of the voltage regulator (REG).Figure from the summary: Figure 1.

Description

Title of the invention: 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 to a lighting control circuit comprising several light sources.

[0003] This disclosure may be applied to exterior vehicle lighting, such as for a door handle. Such lighting illuminates the inside of the door handle at night, making it easier for a user to grasp. Different colored lights can, for example, be used when the vehicle is opened and closed. Previous technique

[0004] In a door handle, there is little space available to house several LEDs and their control electronics. To limit the number of components, it is possible to choose to use LEDs without current control. This then leads to a significant fluctuation in the luminous intensity emitted by each LED.

[0005] It is therefore preferable to have current control for each LED to have better control of the light intensity. To further control the light intensity, it is known to use PWM (Pulse Width Modulation). This uses a signal with a constant frequency and a variable duty cycle. Summary

[0006] The present disclosure aims to provide a control device for multi-LED lighting with current control of each LED, in a compact size so as to be integrated into a confined space such as the inside of a vehicle door handle. This device will preferably allow control of a PWM function to best control the light intensity delivered. Advantageously, the on / off delays of each LED will be as short as possible.

[0007] A control device for at least two light-emitting diodes is proposed, 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 this disclosure, each input intended to receive a control signal is connected via a respective diode to an input of the same voltage regulating device, the voltage regulating device includes an output equipped 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 the switching on / off of said light-emitting diode and, on the other hand, by the voltage at the output of the voltage regulator.

[0009] A diabolo-shaped structure is therefore proposed here. On one side of a voltage regulation device, the power supply signals from 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 described in the following paragraphs may optionally be implemented independently of each other or in combination with each other:

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

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

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

[0014] - the control device further comprises for each light-emitting diode nescente 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, a vehicle door handle lighting system is proposed, comprising a sensor, for example a presence sensor, a control device, and at least one light-emitting diode (LED), said system comprising at least two LEDs, and the control device being a device as described above. In such a lighting system, the LEDs emit, for example, lights of different colors.

[0016] According to another aspect, a motor vehicle is proposed 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 accompanying drawings, on which: Fig. 1

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

[0019] [Fig.2] shows an electronic diagram of a control system according to the present disclosure. Fig. 3

[0020] [Fig.3] shows an operating diagram corresponding to the system of order of the [Fig.2]. Fig. 4

[0021] [Fig.4] schematically shows a vehicle equipped with a lighting system door handle with a control system as described in this disclosure. Description of the implementation methods

[0022] Reference is now made to [Fig. 1]. This figure is a schematic diagram illustrating a control system for three light-emitting diodes LED_1, LED_2, and LED_3. Each diode is associated with its own current-controlling and activation device ACC_1, ACC_2, and ACC_3. It is known to those skilled in the art how to implement current control in a light-emitting diode to control the diode's luminous intensity. Such a control device is illustrated, for example, in [Fig. 2] and will be described later with reference to that 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 an ECU, according to events such as signals received from sensors: presence sensors, light sensor, etc.

[0024] Each of the SC_i signals is applied to an input E_i: this signal is then transmitted directly to a set formed by the corresponding light-emitting diode LED_i and its current control device ACC_i. Each SC_i signal 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 that receives a superposition of the SC_i signals after their respective passage through the diodes D_i. Thus, if one of the SC_i signals is active, that is, if it corresponds to a command to turn on a light-emitting diode LED_i, then the corresponding diode D_i is conducting, and an active signal is applied to the input of the voltage regulation device REG. Conversely, if no SC_i signal is active, that is, if the commands for each light-emitting diode LED_i correspond to an inactive signal, then the corresponding diode D_i is conducting. when the corresponding light-emitting diode is switched off, then no signal is applied to the input of the REG voltage regulation device.

[0026] Figure 1 shows that the voltage regulating 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 regulating device REG, the switch SW being open when the input signal of the voltage regulating device REG is inactive (no input signal) and the switch SW being closed when the input signal of the voltage regulating device REG is active. When the switch SW is closed, the regulated voltage VRef is applied to each pair formed by a corresponding light-emitting diode LED_i and its corresponding current control device ACC_i.

[0027] It is noted that a capacitor Cl is connected to the input of the voltage regulation device REG. This capacitor is sized so that the voltage regulation device REG is supplied without interruption, in particular when it receives an alternating signal at the 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 allows, with a single voltage regulator device REG, the efficient control of a plurality of LEDs LED_1, LED_2, ..., LED_n. Conventionally, a control signal SC_i is generated for each LED to control these LEDs independently of one another, allowing, for example, the ability to turn on one, two, or more without affecting the others. 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 the new control signal is active (at least one of the diodes is conducting), the SW switch is closed and the voltage regulation of the REG voltage regulator device is available for all LEDs LED_i. Since these are also directly controlled by their own SC_i control signal, each LED is then individually driven and operates with both voltage and current control.

[0030] In summary, the structure of [Fig.1] is a "diabolo" structure in which on one side the activation sources 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 [Fig.2], an equivalent diagram illustrates in more detail a control system operating according to the principle illustrated in [Fig.1].

[0032] In the figure on the left, a power supply AL_1 is shown for a first LED_1. This power supply includes a diode in series with a resistor and two capacitors. Only the power supply AL_1 is illustrated in [Fig. 2], but such a power supply is intended for each LED_i in the system, i ranging from 1 to n, where n is a "reasonable" number of diodes to be used here. Most often, n will be 2, 3, or 4 for a lighting application, particularly for lighting a car door handle, but n can of course be greater than 4. In [Fig. 2], three inputs are shown to indicate that there can be multiple inputs.

[0033] Diodes D_i are found here, with i varying from 1 to n. The diagram in [Fig. 2] shows an additional diode D_0 positioned between the parallel-connected diodes D_i and the voltage regulation device REG. This diode D_0 has a reverse-biasing function and ensures that all the current from the inputs E_i flows into the voltage regulation device REG.

[0034] At the output of the voltage regulation device REG, the switch SW is represented by a MOSFET 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 for rapid activation and deactivation of each LED_i.

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

[0036] While [Fig. 2] illustrates in more detail the components used for the implementation of this disclosure, [Fig. 3] illustrates the functions performed within a control system according to this disclosure. To link the two figures, three frames are shown on each of Figures 2 and 3. A first frame Fl corresponds to the control of multiple LEDs. A second frame F2 corresponds to the activation and deactivation of the LEDs, while a third frame F3 concerns the current regulation of the LEDs.

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

[0038] First, there is (outside frames Fl, F2 and F3) 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, that is to say, 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] Within the Fl frame, an "OR" function is applied to the control signals from the AL_i power supplies. This function is implemented 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 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 SW switch (frame F2) which allows for rapid activation and rapid deactivation of the LED_i light-emitting diodes.

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

[0042] As mentioned, such a control device is more specifically intended for a lighting device in the automotive field, for exterior vehicle lighting, such as a door handle. Figure 4 schematically illustrates a vehicle 10 which includes at least one sensor 11 (e.g., a light sensor, a remote control signal receiver, etc.) associated with an electronic controller 13, or electronic control unit (ECU). Within this electronic controller 13, SC_i control signals are generated. These are, for example, PWM signals. These signals are transmitted to the control system described above, housed in a casing 12 which includes, in particular, the AL_i power supplies, the REG voltage regulator, and the SW switch.At the output of box 12, we find the LED_i light-emitting diodes and their ACC_i current control devices which are integrated for example in a vehicle door handle. 10.

[0043] The sensor(s) 11 allow(s) the lighting to be controlled under certain predefined conditions. For example, a light sensor can be used to avoid turning on the lighting device during the day. A remote control receiver can be used to control the desired type of lighting: depending on the button pressed on the remote control, the light can be a specific color, gradually brighten, flash, etc. The sensor 11 can also be a capacitive presence sensor that detects, for example, the approach of a user, or more precisely, their hand. Of course, as suggested, several sensors can be used, and the controlled lighting will be determined based on the information received from the multiple sensors.

[0044] The control system described above allows several light-emitting diodes (at least two, or even more than three) to be controlled independently of each other. The proposed structure allows for a small footprint, making it possible to use multiple lighting systems in a confined space, particularly in a door handle approximately 10 cm long, a few centimeters high, and thin.

[0045] The control system for at least two light sources (LEDs or light-emitting diodes) includes a single voltage regulator, common to all the LEDs. A control signal specific to each light source passes through a diode, and the resulting signals are combined at the input of the voltage regulator. The diodes supply current to the voltage regulator when at least one of the control signals is not zero. The output switch of the voltage regulator is controlled by the input signal of the voltage regulator.

[0046] In the case of a PWM (pulse-width modulation) control signal, said signal consists of a short-duration alternating high signal and a long-duration low signal. In the preferred embodiment with a capacitor at the input of the voltage regulating device, said device is continuously powered even when it receives an alternating signal.

[0047] The embodiment with a MOSFET transistor switch is advantageous because the presence of this MOSFET transistor allows the current control means for the LEDs to be disconnected from the voltage regulator when the control signal goes low (during pulse-width modulation). The proposed structure advantageously eliminates the need to draw current from the voltage regulator. The latter can then continue to operate thanks to the reserve provided by capacitors C1 and C2. When the input voltage of the pulse-width modulator rises again in the next cycle, the voltage regulator does not exhibit of ignition delay because it is already in operation. Such an ignition 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 diodes is generally very fast (less than, for example, 50 ns (i.e., 5 x 10^-8 s)) compared to a pulse-width modulation period (on the order of a millisecond, i.e., 1 x 10^-3 s). The impact of this response time on the modulation is therefore truly marginal.

[0049] This disclosure is not limited to the examples of implementation and applications described above, only as non-limiting examples, but encompasses all the variants that a person skilled in the art may consider within the framework of the protection sought.

Claims

Claims

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 (SC_i) for said light-emitting diode (LED_i), and - current control means (ACC_i) for said light-emitting diode, characterized in that: - each input intended to receive a control signal (SC_i) is connected via a respective diode (D_i) to an input of the same voltage regulation device (REG), - the voltage regulation device (REG) comprises an output provided with a switch (SW) controlled by a signal supplying said voltage regulation device at the input, and - the current control means (ACC_i) of a light-emitting diode (LED_i) are supplied, on the one hand, by the control signal (SC_i) received on the corresponding input of the control device,for switching on / off said light-emitting diode (LED_i), and, on the other hand, by the voltage (Vref) at the output of the voltage regulator (REG).,

2. Control device according to claim 1, characterized in that the switch (SW) is a MOSFET type transistor.

3. Control device according to one of claims 1 or 2, characterized in that the voltage regulating device (REG) has a capacitor (Cl) at its input, arranged between the input of said voltage regulating device (REG) and the respective diodes (D_i).

4. Control device according to one of claims 1 to 3, characterized in that the voltage regulating device (REG) has a capacitor (C2) at its output, upstream of the switch (SW).

5. Control device according to one of claims 1 to 4, characterized in that it further comprises, for each light-emitting diode (LED_i), a PWM type signal generator, i.e. pulse width modulation, connected to the corresponding input intended to receive a control signal (SC_i).

6. Motor vehicle door handle lighting system, comprising a sensor (11), a control device and at least one light-emitting diode (LED_i), characterized in that it comprises at least at least two light-emitting diodes, and in that the control device is a device according to one of claims 1 to 5.

7. Handle lighting system according to claim 6, characterized in that the light-emitting diodes (LED_i) emit lights of different colors.

8. Motor vehicle, characterized in that it comprises a lighting system according to one of claims 6 or 7.

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