Electronic assembly for automotive light emitting device and automotive light emitting device - Patents.com

Abstract

The present invention provides an electronic assembly for an automotive lighting device (10), comprising a light source (1), a driver (3) for controlling the light source (1), and an input protection circuit (2). The input protection circuit (2) is disposed between a power source and the light source (1) and comprises a protection input (21) and a protection output (22). The protection input (21) and the protection output (22) are connected via a resistor group comprising a resistor (23) and a diode (24) connected in series. The node between the protection input (21) and the resistor group is connected to ground via a first capacitor (25), and the node between the resistor group and the protection output (22) is connected to ground via a second capacitor (26).

Description

[Technical field]

[0001] The present invention is in the field of electronic arrangements for controlling automotive light sources. [Background technology]

[0002] The automotive lighting market can be considered one of the most competitive, with a constant need for new lighting functions. Some customer trends include the use of RGB (Red Green Blue) solid-state light sources, such as RGB LEDs (Light Emitting Diodes), to perform required lighting and signaling functions.

[0003] However, these elements and their drivers require special input protection to avoid transient pulses that exceed maximum voltages and thereby may damage the elements and their drivers and thus cause system malfunctions.

[0004] To prevent this from happening, input protection circuits typically employ transient voltage suppressors, however these elements are typically heavy, expensive and large.

[0005] The present invention provides an alternative arrangement for providing a controlled grouping of solid state light sources in an electronic assembly for an automotive lighting device that seeks to overcome these drawbacks. Summary of the Invention

[0006] The present invention provides an alternative solution to manage the current needs of light sources for automotive light emitting devices by an electronic assembly for the automotive light emitting device, the electronic assembly comprising: A light source; a driver configured to control the operation of a light source; a power source configured to provide an electrical supply to the light source and to the driver; an input protection circuit arranged between a power source and a light source, the input protection circuit being intended to limit transient voltages and / or currents received by the light source and / or by the driver, the input protection circuit comprising a protection input and a protection output; Equipped with the protection input and the protection output are connected by means of a group of resistors and diodes connected in series, the diodes having an anode terminal and a cathode terminal; the anode terminal of the diode is connected directly or via a resistor to the protection input; a node between the protection input and the resistor group is connected to ground via a first capacitor; The node between the resistor group and the protected output is connected to ground via a second capacitor.

[0007] The automotive light emitting device is configured to filter all dangerous pulses without the need for suitable transient voltage suppressors, which are expensive, large elements and take up a lot of space on the board, a problem that is important for interior lighting RGB modules.

[0008] The anode terminal of the diode is connected to the protection input, allowing current to flow freely towards the module driver while protecting the driver from current reversal.

[0009] Preferably, the cathode terminal of the diode is connected directly to the protected output via a resistor.

[0010] In some particular embodiments, the resistor is located closer to the protected output than the diode.

[0011] This advantageous position of the resistor after the diode in the current direction results in a particularly favorable behavior for negative pulses, however, various configurations between the resistor and the diode are also suitable.

[0012] When the resistor is located closer to the protection output than the diode, the anode of the diode is preferably connected to the protection circuit input, the cathode of the diode is connected to the resistor, and the resistor is connected to the protection circuit output.

[0013] In some particular embodiments, the first capacitor has a capacitance value of greater than 47 nF, in particular greater than or equal to 68 nF, in particular greater than or equal to 100 nF.

[0014] These values ​​are sufficient to provide protection against electrostatic discharge.

[0015] In some particular embodiments, the second capacitor has a capacitance value of 2.2 μF or greater, and in particular 4.7 μF or greater.

[0016] These high values, compared to known systems, are intended to provide protection against dangerous pulses without the need for transient voltage suppressors.

[0017] In some particular embodiments, the resistor has a resistance value between 10 and 40 ohms.

[0018] In the steady state region, a high resistance value is advantageous to provide power sharing between the driver and the resistor, so the driver can supply a high current to the load (LED), thus increasing its power supply capability, since the extra heat dissipation caused by the voltage rise in the power supply is shared between the resistor and the driver.

[0019] However, due to some specific pulses such as cold start, the voltage may drop to 6V during a transient period and the system will operate at a lower voltage value from the power supply, a lower resistance value is advantageous to reduce the voltage drop across the resistor. The claimed range provides an advantageous compromise.

[0020] In some particular embodiments, the driver is a DC / DC driver.

[0021] In some particular embodiments, the driver is a linear driver.

[0022] A linear driver is a simple element that can manage the operation of a single LED.

[0023] In some particular embodiments, the light source is a solid-state light source.

[0024] 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 produces visible light with less heat and less energy dissipation. The typically small mass of solid-state electronic lighting devices results in greater resistance to shock and vibration compared to brittle glass tubes / bulbs and elongated filament wires. They also eliminate filament evaporation, potentially extending the life of the lighting device. Some examples of these types of lighting include semiconductor light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), or polymer light-emitting diodes (PLEDs) as the illumination source, rather than electric filaments, plasmas, or gases.

[0025] In some particular embodiments, the light source includes at least one RGB LED.

[0026] RGB LEDs are useful for providing a variety of colors with a single element. These elements can also be managed by linear drivers.

[0027] The present invention is particularly suited for powering RGB LEDs, which require relatively low power compared to typical automotive lighting applications. In particular, the present invention is best suited for interior lighting, where RGB LEDs may be used in accordance with color regulations that exist in the automotive lighting field that limit the color of the lighting on the exterior of the vehicle, whereas no such regulations exist for interior lighting.

[0028] Furthermore, interior lighting uses relatively low current compared to exterior lighting, which means similarly low power dissipation due to the Joule effect on the resistor group placed in series within the input protection circuit and therefore in series with the current powering the driver. In high power applications, such as some exterior lighting applications, such a design means high power dissipation, which may make the protection circuit inadequate in such cases.

[0029] In a further inventive aspect, the present invention provides an automotive light emitting device comprising an electronic assembly according to the first inventive aspect and an optical element configured to project light emitted by the light source.

[0030] Unless otherwise defined, all terms (including technical and scientific terms) used herein should be interpreted as being conventional in the art. It will be further understood that terms in common usage should also be interpreted as being conventional in the relevant art, and not in an idealized or overly formal sense, unless expressly so defined herein.

[0031] In this specification, the term "comprise" and its derivatives (such as "comprising") should not be understood in an exclusive sense, i.e., these terms should not be interpreted as excluding the possibility that what is described and defined may include additional elements, steps, etc.

[0032] To complete the description and to provide a suitable understanding of the invention, a set of drawings is provided, which form an integral part of the description, illustrate embodiments of the invention, and should not be interpreted as limiting the scope of the invention, but only as an example of how the invention may be practiced. The drawings include the following figures: [Brief description of the drawings]

[0033] [Figure 1]FIG. 2 shows the scheme of an electronic assembly according to the invention. [Diagram 2] FIG. 2 illustrates the electrical scheme of a protected input circuit provided in a particular embodiment of an electronic arrangement according to the invention. [Diagram 3] FIG. 1 shows a car equipped with an interior light emitting device having such an electronic configuration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] In these figures, the following reference numbers are used for the following elements: 1 LED 2 Input protection circuit 21 Protected Input 22 Protected Output 23 Resistance 24 Diode 25 First Capacitor 26 Second Capacitor 3 Driver 4 Power source 10 Light emitting devices for automobiles 100 Automobiles

[0035] The exemplary embodiments are described in sufficient detail to enable those skilled in the art to embody and practice the systems and processes described herein, it is important to understand that the embodiments may be provided in many alternative forms and should not be construed as being limited to the examples set forth herein.

[0036] Thus, while the embodiments can be modified in various ways and can take various alternative forms, specific embodiments thereof are shown in the drawings and will be described in detail below by way of example. There is no intention to be limited to the particular forms disclosed. On the contrary, all modifications, equivalents, and alternatives falling within the scope of the appended claims should be covered. Elements of the exemplary embodiments are consistently designated by the same reference numerals throughout the drawings and detailed description, where appropriate.

[0037] FIG. 1 shows the scheme of an electronic assembly according to the invention.

[0038] In this figure, a driver element 3 is configured to control the operation of an RGB LED 1 .

[0039] The driver element 3 receives two inputs: a power input 31 coming from the input protection circuit 2 and a control input 32 intended to control the operation of the RGB LED 1 .

[0040] The input protection circuit 2 in turn receives power from a power source 4 which comes from the vehicle's battery.

[0041] The input protection circuit 2 is therefore configured to filter out any potentially dangerous pulses coming from the power supply, so that neither the driver nor the LED receives any current or voltage pulses.

[0042] As can be seen in this figure, the input protection circuit comprises a protection input 21 receiving the power supply and a protection output 22 connected to the parallel connection of the driver and the light source. The input protection circuit 2 therefore acts on both the LED 1 and the driver 3.

[0043] The driver is a linear driver specifically adapted to control the operation of the RGB LED1.

[0044] FIG. 2 shows the electrical scheme of a protected input circuit included in a particular embodiment of an electronic arrangement according to the invention.

[0045] The figure shows a protected input 21 which receives a power supply, and a protected output 22 which is connected to a parallel connection of drivers and LEDs.

[0046] Between the protection input 21 and the protection output 22 there is a group of resistor 23 and diode 24. In this case, the resistor 23 is located after the diode 24 due to the preferred behavior of the arrangement for negative pulses. However, in different embodiments, the diode 24 can be located after the resistor 23.

[0047] The input protection circuit further comprises a first capacitor 25 and a second capacitor 26. A node between the protection input 21 and the resistor group is connected to ground via the first capacitor 25, and a node between the resistor group and the protection output 22 is connected to ground via the second capacitor 26.

[0048] The first capacitor has a capacitance value of 2.2 μF while the second capacitor has a capacitance value of 4.7 μF. The resistor has a resistance value of 33 Ω. These values ​​avoid dangerous pulses and the operation of the circuit is fully customized to control the operation of the RGB LED 1 by the driver 3. These values ​​are only exemplary and depend on the car manufacturer's specifications and local regulations.

[0049] FIG. 3 shows an automobile 100 with an interior light emitting device 10 having such an electronic configuration and an optical lens for projecting the light emitted by the RGB LEDs.

Claims

1. An electronic assembly for an automotive light emitting device (10), the electronic assembly comprising: a light source (1), a driver (3) configured to control the operation of said light source (1), said driver (3) comprising a driver power input and a driver control input, said light source being electrically connected to said driver control input; a power source (4) configured to provide an electrical supply to said light source and to said driver; an input protection circuit (2) arranged between the power supply and the light source (1), the input protection circuit (2) being intended to limit transient voltages and / or currents received by the light source and / or by the driver, the input protection circuit (2) comprising a protection input (21) and a protection output (22); Equipped with the protection input (21) and the protection output (22) are connected via a resistor group comprising a resistor (23) and a diode (24) connected in series, the diode (24) having an anode terminal and a cathode terminal, the anode terminal of said diode is connected to said protection input, either directly or via said resistor, the node between said protection input (21) and said resistor group is connected to ground via a first capacitor (25); the node between said resistor group and said protection output (22) is connected to ground via a second capacitor (26); Electronic assembly.

2. 2. The electronic assembly of claim 1, wherein the input protection circuit (2) is also located between the power supply and the driver power input.

3. 3. An electronic assembly according to claim 1 or 2, wherein the first capacitor (25) has a capacitance value higher than 47 nF, in particular 68 nF or more, in particular 100 nF or more.

4. 4. An electronic assembly according to any one of the preceding claims, wherein the second capacitor (26) has a capacitance value of 2.2 μF or more, in particular 4.7 μF or more.

5. An electronic assembly according to any one of the preceding claims, wherein the resistor (23) has a resistance value comprised between 10Ω and 40Ω.

6. 6. An electronic assembly according to claim 1, wherein the driver is a DC / DC driver.

7. 6. An electronic assembly according to claim 1, wherein the driver is a linear driver.

8. The electronic assembly of claim 1 , wherein the light source is a solid-state light source.

9. 9. An electronic assembly according to any one of the preceding claims, wherein the light source comprises at least one RGB LED (1).

10. 10. An electronic assembly as claimed in any preceding claim, wherein the resistor is located closer to the protected output than the diode.

11. An electronic assembly according to any one of claims 1 to 10; an optical element configured to project light emitted by the light source; An automotive light emitting device (100) comprising:

Images