EP3857665A1 - Voltage-controlled matrix light source with diagnostic circuit for a motor vehicle - Google Patents
Voltage-controlled matrix light source with diagnostic circuit for a motor vehicleInfo
- Publication number
- EP3857665A1 EP3857665A1 EP19773092.2A EP19773092A EP3857665A1 EP 3857665 A1 EP3857665 A1 EP 3857665A1 EP 19773092 A EP19773092 A EP 19773092A EP 3857665 A1 EP3857665 A1 EP 3857665A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- light source
- elementary
- matrix
- voltage
- source
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
- H05B45/58—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits involving end of life detection of LEDs
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/40—Details of LED load circuits
- H05B45/44—Details of LED load circuits with an active control inside an LED matrix
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
Definitions
- the invention relates to matrix light sources with semiconductor elements
- the invention relates to a voltage-controlled matrix light source, with diagnostic circuit.
- a light emitting diode is a semiconductor electronic component capable of emitting light when it is traversed by an electric current.
- LED technology is increasingly used for various light signaling solutions. LEDs are used to perform light functions such as daytime running lights, signaling lights, etc.
- the light intensity emitted by an LED is generally dependent on the intensity of the electric current flowing through it.
- an LED is characterized by an electric current intensity threshold value. This maximum forward current is generally decreasing at increasing temperature.
- forward voltage direct or nominal voltage
- elementary light emitting is interesting in many fields of application, and in particular also in the field of lighting and signaling of motor vehicles.
- an array of LEDs can be used to create interesting light beam shapes for light functions such as high beam or daytime running light.
- several different light functions can be performed using a single matrix, thereby reducing the physical size in the confined space of a motor vehicle light.
- matrix light sources or, equivalently, pixelated, are controlled by a physically remote control unit and electrically connected to the light source.
- This unit can also perform diagnostic functions in relation to the operation of the matrix source and / or of the elementary light sources which constitute it.
- matrix light sources controlled in voltage it is difficult to diagnose a fault in open circuit of an elementary light source. Indeed, such a source involves a MOSFET type transistor with low voltage drop between its drain and source terminals, to connect / disconnect an elementary light source selectively to / from the voltage source. It therefore becomes difficult to discern between a non-defective source and an open circuit fault source having for example a defective anode and / or cathode terminal.
- the invention aims to overcome at least one of the problems posed by the prior art. More specifically, the invention aims to propose a matrix or pixelated light source controlled in voltage, capable of diagnosing a fault in the open circuit of one of its constituent light emitting light sources.
- a matrix light source intended to be supplied with electric voltage and comprising an integrated circuit as well as a matrix of elementary light sources with electroluminescent semiconductor element.
- the matrix source is remarkable in that the integrated circuit is in contact with the matrix and comprises, for each elementary light source, a switching device making it possible to connect it selectively to a source of electric voltage as a function of a first control signal.
- the integrated circuit further comprises, for at least one of the elementary light sources, a circuit for detecting an open circuit fault of the elementary light source.
- an integrated circuit for a matrix light source is proposed.
- the integrated circuit is intended to be in mechanical and electrical contact with a matrix of elementary light sources of the matrix light source.
- the integrated circuit is remarkable in that it includes, for each elementary light source, a switch device enabling it to be connected selectively to a source of electric voltage as a function of a first control signal.
- the integrated circuit further comprises, for at least one of the elementary light sources, a circuit for detecting an open circuit fault of the elementary light source.
- the matrix of elementary light sources may preferably comprise a common substrate supporting the elementary light sources.
- the common matrix substrate may preferably include SiC.
- the integrated circuit may preferably comprise an Si substrate.
- the integrated circuit is welded or glued to the matrix of elementary light sources, for example to a common substrate supporting the elementary light sources.
- the integrated circuit is preferably soldered or glued to the underside of the common substrate, opposite the face which comprises the elementary light sources.
- the integrated circuit is in mechanical contact, for example by means of fixing means, and electrical with the common substrate, which has electrical connection zones on its underside.
- the detection circuit can be configured to generate binary information for detecting an open circuit fault of said elementary light source.
- the detection circuit can preferably comprise a memory element, the detection circuit being configured to store the detection information in said memory element.
- the detection circuit may preferably include a load mounted in parallel with the switch device, so that an electrical current of non-negligible intensity crosses the load if the matrix source is supplied with electricity, unless the source elementary light has an open circuit fault.
- the detection circuit may comprise a comparison unit, configured so as to compare the voltage drop across the terminals of said load with a predetermined threshold value.
- Said load may preferably comprise a resistor mounted in parallel with the switch device.
- the load can comprise a transistor controlled by a second control signal, the transistor representing a non-negligible resistance when it is in the closed state, and characterized in that the detection circuit comprises a control unit for generating said second control signal.
- the second control signal can preferably depend on the first control signal.
- the integrated circuit may preferably include a dedicated open circuit fault detection circuit for each of the elementary light sources.
- the elementary light sources can be arranged in at least two branches of parallel sources.
- a light module for a motor vehicle comprising a matrix light source and a circuit for controlling the electrical supply of said source.
- the light module is remarkable in that the matrix light source conforms to one aspect of the invention.
- a method for detecting an open circuit fault of an elementary light source with an electroluminescent semiconductor element of a matrix light source supplied with electric voltage and having a plurality of such sources elementary light as well as a common substrate is proposed.
- the substrate is in contact with an integrated circuit which includes, for each elementary light source, a switching device making it possible to connect it selectively to the voltage source as a function of a first control signal.
- the process is remarkable in that it comprises the following stages:
- a device for controlling the matrix light source generating at least a first signal making it possible to control the state of the switch device so as to selectively connect at least one elementary light source from the matrix light source to the voltage source;
- the pixelated light source may preferably comprise at least one matrix of electroluminescent elements - elementary light sources - (called in English monolithic array) arranged in at least two columns by at least two lines.
- the electroluminescent source comprises at least one matrix of monolithic electroluminescent elements, also called monolithic matrix.
- the electroluminescent elements are grown from a common substrate and are electrically connected so as to be selectively activatable, individually or by subset of electroluminescent elements.
- each electroluminescent element or group of electroluminescent elements can form one of the elementary emitters of said pixelated light source which can emit light when its or their material is supplied with electricity
- electroluminescent elements can meet this definition of monolithic matrix, since the electroluminescent elements have one of their main elongation dimensions substantially perpendicular to a common substrate and that the spacing between the elementary emitters, formed by one or more electroluminescent elements grouped together electrically, is low in comparison with the spacings imposed in known arrangements of flat square chips soldered on a printed circuit board.
- the substrate can be predominantly made of semiconductor material.
- the substrate may include one or more other materials, for example non-semiconductors.
- These electroluminescent elements, of submillimetric dimensions are for example arranged projecting from the substrate so as to form rods of hexagonal section. The light-emitting sticks arise on a first face of a substrate.
- Each electroluminescent rod here formed by the use of gallium nitride (GaN), extends perpendicularly, or substantially perpendicularly, projecting from the substrate, here made from silicon, other materials such as silicon carbide which can be used without get out of the context of the invention.
- the light-emitting sticks could be made from an alloy of aluminum nitride and gallium nitride (AlGaN), or from an alloy of aluminum phosphides, indium and gallium (AlInGaP).
- Each electroluminescent rod extends along an elongation axis defining its height, the base of each rod being arranged in a plane of the upper face of the substrate.
- the light-emitting sticks of the same monolithic matrix advantageously have the same shape and the same dimensions. They are each delimited by a terminal face and by a circumferential wall which extends along the axis of extension of the rod.
- the light-emitting rods are doped and are the subject of a polarization, the resulting light at the output of the semiconductor source is emitted essentially from the circumferential wall, it being understood that light rays can also emerge from the face terminal.
- each light-emitting stick acts as a single light-emitting diode and the luminance of this source is improved on the one hand by the density of the light-emitting sticks present and on the other hand by the size of the illuminating surface defined by the circumferential wall. and which therefore extends over the entire periphery, and the entire height, of the stick.
- the height of a stick can be between 2 and 10 ⁇ m, preferably 8 ⁇ m; the largest dimension of the end face of a rod is less than 2 ⁇ m, preferably less than or equal to 1 ⁇ m.
- the height can be modified from one zone of the pixelated light source to another, so as to increase the luminance of the corresponding zone when the average height of the rods constituting it is increased.
- a group of light-emitting sticks can have a height, or heights, different from another group of light-emitting sticks, these two groups being constitutive of the same semiconductor light source comprising light-emitting sticks of submillimetric dimensions.
- the shape of the light-emitting rods can also vary from one monolithic matrix to another, in particular on the section of the rods and on the shape of the end face.
- the rods have a generally cylindrical shape, and they can in particular have a shape of polygonal section, and more particularly hexagonal. We understand that it is important that light can be emitted through the circumferential wall, whether the latter has a polygonal or circular shape.
- the end face may have a substantially planar shape and perpendicular to the circumferential wall, so that it extends substantially parallel to the upper face of the substrate, or it may have a domed or pointed shape at its center. , so as to multiply the directions of emission of the light leaving this end face.
- the light-emitting sticks can preferably be arranged in a two-dimensional matrix. This arrangement could be such that the sticks are staggered. Generally, the sticks are arranged at regular intervals on the substrate and the separation distance of two immediately adjacent light-emitting sticks, in each of the dimensions of the matrix, must be at least equal to 2 ⁇ m, preferably between 3 and 10 hours. mhi, so that the light emitted by the circumferential wall of each rod can leave the matrix of light-emitting rods. Furthermore, it is expected that these separation distances, measured between two axes of extension of adjacent rods, will not be greater than 100 ⁇ m.
- the monolithic matrix may comprise electroluminescent elements formed by layers of epitaxial electroluminescent elements, in particular a first layer of GaN doped n and a second layer of GaN doped p, on a single substrate, for example made of silicon carbide, and which is cut (by grinding and / or ablation) to form a plurality of elementary emitters respectively from the same substrate.
- electroluminescent elements formed by layers of epitaxial electroluminescent elements, in particular a first layer of GaN doped n and a second layer of GaN doped p, on a single substrate, for example made of silicon carbide, and which is cut (by grinding and / or ablation) to form a plurality of elementary emitters respectively from the same substrate.
- the substrate of the monolithic matrix may have a thickness of between 10 ⁇ m and 800 ⁇ m, in particular equal to 200 ⁇ m; each block can have a length and a width, each being between 50 ⁇ m and 500 ⁇ m, preferably between 100 ⁇ m and 200 ⁇ m. In a variant, the length and the width are equal.
- the height of each block is less than 500 ⁇ m, preferably less than 300 ⁇ m.
- each block can be made via the substrate on the side opposite the epitaxy.
- the separation distance between two elementary transmitters can be less than 1 mm, in particular less than 500 ⁇ m, and it is preferably less than 200 ⁇ m.
- the monolithic matrix can further comprise a layer of a polymer material in which the electroluminescent elements are at least partially embedded.
- the layer can thus extend over the entire extent of the substrate or only around a determined group of electroluminescent elements.
- the polymer material which can in particular be based on silicone, creates a protective layer which makes it possible to protect the electroluminescent elements without hampering the diffusion of the light rays.
- wavelength conversion means capable of absorbing at least part of the rays emitted by one of the elements and of converting at least part of said excitation light absorbed into emission light having a wavelength different from that of the excitation light. It is equally possible to provide that the phosphors are embedded in the mass of the polymeric material, or else that they are arranged on the surface of the layer of this polymeric material.
- the pixelated light source may further include a coating of reflective material to deflect the light rays towards the exit surfaces of the light source.
- the electroluminescent elements of submillimetric dimensions define in a plane, substantially parallel to the substrate, a determined outlet surface.
- a determined outlet surface we understand that the shape of this exit surface is defined according to the number and arrangement of the elements
- a pixelated light source or in an equivalent manner a matrix light source, intended to be voltage-controlled, and capable of diagnosing an open circuit fault of one of its elementary sources or constituent pixels.
- a load mounted in parallel with the transistor which makes it possible to connect / disconnect an elementary light source from the matrix light source to its voltage source, a measurable leakage current is generated through the load, the measurement of the intensity of which used to diagnose an open circuit fault of the elementary light source in question.
- this load additionally comprises a controlled transistor, the leakage current only flows when a diagnostic is in progress, which avoids unnecessary current leaks having a potential impact on the normal operation of the matrix light source.
- the diagnostic and reaction circuit is integrated into the matrix light source, it is able to be activated quickly.
- Figure 1 schematically shows a matrix light source according to a preferred embodiment of the invention
- Figure 2 shows schematically a matrix light source according to a preferred embodiment of the invention
- Figure 3 shows schematically a matrix light source according to a preferred embodiment of the invention
- Figure 4 schematically shows a matrix light source according to a preferred embodiment of the invention
- Figure 5 shows schematically a matrix light source according to a preferred embodiment of the invention.
- references 100, 200, 300, 400 and 500 denote five embodiments of a matrix light source according to the invention.
- the illustration of Figure 1 shows a pixelated or matrix light source 100 according to a preferred embodiment of the invention.
- the matrix light source 100 is intended to be voltage-controlled and comprises a plurality of elementary light sources with an electroluminescent semiconductor element 110 and a common substrate, not shown, in electrical and mechanical contact with, and functionally connected to an integrated circuit 120
- the elementary light sources are typically light-emitting diodes, LEDs.
- the matrix light source 100 preferably comprises a monolithic matrix component, in which the semiconductor layers of the elementary light sources 110 are, for example, arranged on the common substrate.
- the matrix of elementary light sources 110 preferably comprises a parallel mounting of a plurality of branches, each branch comprising light emitting semiconductor light sources 110.
- the matrix of elementary light sources comprises by way of example and without limitation, depending on the thickness of the substrate and starting at the end opposite to the location of the elementary sources 110, a first electrically conductive layer deposited on an electrically insulating substrate . It follows an n-doped semiconductor layer, the thickness of which is between 0.1 and 2 mih. This thickness is clearly less than that of known light-emitting diodes, for which the corresponding layer has a thickness of the order of 1 to 2 ⁇ m.
- the next layer is the active quantum well layer with a thickness of about 30 nm, followed by an electron blocking layer, and finally a p-doped semiconductor layer, the latter having a thickness of about 300nm.
- the first layer is a layer of (Al) GaN: Si
- the second layer a layer of n-GaN: Si
- the active layer comprises quantum wells in InGaN alternating with barriers in GaN.
- the blocking layer is preferably made of AlGaN: Mg and the p-doped layer is preferably made of p-GaN: Mg.
- the n-doped Galium nitride has a resistivity of 0.0005 Ohm / cm while the p-doped Galium nitride has a resistivity of 1 Ohm / cm.
- the thicknesses of the proposed layers make it possible in particular to increase the internal series resistance of the elementary source, while significantly reducing its manufacturing time, as the doped layer n is thinner compared to known LEDs and requires less deposition time important. For example, typically 5 hours of MOCVD deposition time is required for a standard configuration LED with 2m of layer n, and this time can be reduced by 50% if the thickness of layer n is reduced to 0.2 m.
- the monolithic component 100 is preferably manufactured by depositing the layers in a homogeneous and uniform manner on at least part of the surface of the substrate, so to cover it.
- the deposition of the layers is for example carried out by a process of epitaxy in the vapor phase with organometallics (“metal oxide Chemical vapor deposition”), MOCVD.
- organometallics metal oxide Chemical vapor deposition
- Such methods and reactors for their implementation are known for depositing semiconductor layers on a substrate, for example from patent documents WO 2010/072380 A1 or WO 01/46498 A1. The details of their implementation will therefore not be detailed in the context of the present invention.
- the layers thus formed are pixelated.
- the layers are removed by known lithographic methods and by etching at the locations which subsequently correspond to the spaces separating the elementary light sources 110 from one another on the substrate.
- a plurality of several tens or hundreds or thousands of pixels 110 of surface less than one square millimeter for each individual pixel, and of total surface greater than 2 square millimeter having semiconductor layers with homogeneous thicknesses, and therefore having homogeneous and high internal series resistances can be produced on the substrate of a matrix light source 100.
- the more the size of each pixel of LED decreases the more its series resistance increases, and the more this pixel is adapted to be driven by a voltage source.
- the substrate comprising the epitaxial layers covering at least part of the surface of the substrate is sawn or cut into elementary light sources, each of the elementary light sources having similar characteristics in terms of their internal series resistance.
- the invention likewise relates to types of elementary light sources with semiconductor elements implying other configurations of semiconductor layers.
- the substrates, the semiconductor materials of the layers, the arrangement of the layers, their thicknesses and any vias between the layers may be different from the example which has just been described, provided that the structure of the semi layers -conductive is such that the internal series resistance of the elementary light source which results therefrom is at least 1 Ohm, and preferably at least 5 or 10 Ohm, or even between 1 and 100 Ohm.
- the integrated circuit 120 is preferably soldered to the substrate of the monolithic source and further comprises for at least one, but preferably for all the elementary light sources 110, an open-circuit fault detection circuit 130.
- the matrix light source 100 is intended to be voltage-controlled by a circuit for controlling the power supply 10.
- Such circuits are per se known in the art and their operation will not be described in detail in the context of the present invention. They involve at least one converter circuit capable of converting an input voltage, supplied for example by a voltage source internal to a motor vehicle, such as a battery, into an output voltage, of intensity adapted to supply the source. bright matrix.
- the control of each elementary source, or in an equivalent manner, of each pixel is reduced to the control of a switch device 132 as shown diagrammatically in FIG. 1.
- the elementary light source 110 can be selectively connected to the voltage source 10.
- the switching device is for example produced by a field effect transistor of MOSFET type preferably characterized by a drop of low voltage between its drain and source terminals, and controlled by a control signal from a control unit external to the matrix light source.
- a supply circuit can be integrated into the substrate 120 during the manufacture of the monolithic component 100.
- the illustration of Figure 2 shows a pixelated or matrix light source 200 according to another preferred embodiment of the invention.
- the matrix light source 200 is intended to be voltage-controlled and comprises a plurality of elementary light sources with an electroluminescent semiconductor element 210 and a common substrate, not shown, in contact with an integrated circuit 220 to which the substrate is functionally connected.
- the elementary light sources are typically light-emitting diodes, LEDs.
- the integrated circuit 220 further comprises for at least one elementary light source 210, an open circuit fault detection circuit 230.
- the control of each elementary source, or in an equivalent manner , of each pixel is reduced to the control of a switch device 232.
- the elementary light source 210 can be selectively connected to the voltage source 10.
- the switch device 232 is for example produced by a MOSFET type field effect transistor preferably characterized by a low voltage drop between its drain and source terminals, and controlled by a control signal 12 coming from a control unit external to the matrix light source.
- FIG. 2 shows a control signal 12 intended for a plurality of elementary light sources 210.
- each elementary light source 210 is controlled by a control signal 12 which is specific.
- the open circuit fault detection circuit 230 further comprises a load 234, mounted in parallel with the switch device 232.
- a load 234 mounted in parallel with the switch device 232.
- FIG. 3 shows a pixelated or matrix light source 300 according to another preferred embodiment of the invention.
- the matrix light source 300 is intended to be voltage-controlled and comprises a plurality of elementary light sources with an electroluminescent semiconductor element 310 and a common substrate, not shown, in contact with an integrated circuit 320.
- the integrated circuit 320 further comprises for at least one elementary light source 310, an open circuit fault detection circuit 330.
- the control of each elementary source, or in an equivalent manner , of each pixel is reduced to the control of a MOSFET type field effect transistor device 332.
- the elementary light source 310 can be selectively connected to the voltage source 10
- the transistor is preferably characterized by a low voltage drop between its drain and source terminals. It is and controlled by a control signal 12 coming from a control unit external to the matrix light source. If the transistor 232 is on, the elementary light source 310 is energized and it lights up if it is not defective. If, on the other hand, the transistor is in its blocking state, the elementary light source 310 is not connected to the voltage source.
- the open circuit fault detection circuit 330 further comprises a load 334 comprising a resistor, for example of 700 Ohm, mounted in parallel with the switching device 332.
- a load 334 comprising a resistor, for example of 700 Ohm, mounted in parallel with the switching device 332.
- a fault detection indication is recorded in a memory element 336 provided for this purpose.
- the detection information which is preferably binary information, accessible to an external entity which is arranged to read the content of the memory element 336.
- This embodiment solves the problem of diagnosing a fault by open circuit. However, it generates a constant current leak.
- the illustration in Figure 4 shows a pixelated or matrix light source 400 according to another preferred embodiment of the invention.
- the matrix light source 400 is intended to be voltage-controlled and comprises a plurality of elementary light sources with an electroluminescent semiconductor element 410 and a common substrate 420.
- the substrate 420 further comprises, for at least one elementary light source 410, an open-circuit fault detection circuit 430.
- the control of each elementary source, or in an equivalent manner, of each pixel is reduced to the control of a MOSFET type field effect transistor device 432.
- the elementary light source 410 can be selectively connected to the voltage source 10.
- the transistor 432 is preferably characterized by a low voltage drop between its drain and source terminals. 11 is and controlled by a control signal 12 coming from a control unit external to the matrix light source.
- the open circuit fault detection circuit 440 further comprises a load 434 comprising a second transistor preferably characterized by a large voltage drop between its drain and source terminals, for example of the order of 0.7V, mounted in parallel with the first transistor 432.
- the state of the transistor 434 is controlled by a control signal 14 coming in the case illustrated by FIG. 4 of a control unit external to the matrix light source. This arrangement makes it possible to control the transistor 434 only in passing mode when an open-circuit fault diagnosis takes place.
- An open circuit fault of the elementary light source 410 is detectable when the first transistor (switch) 432 is blocking, while the second transistor (load) 434 is on.
- the second transistor 434 can for example be controlled in passing mode briefly before the first transistor becomes on.
- the second transistor 434 can be controlled in briefly passing mode before the first transistor 432 is switched from its passing mode to the blocking mode, the second transistor 434 subsequently remaining passing for a predetermined period of time.
- Other combinations are possible without departing from the scope of the present invention and without creating optically perceptible effects in the light flux emitted by the matrix light source.
- the comparison circuit 438 compares the voltage drop across the load 434 with a predetermined threshold value.
- the threshold value can for example be 0.7 V. If the voltage drop across the resistor 434 is less than 0.7 V, a fault detection indication is recorded in a memory element 436 provided for this purpose. This makes the detection information, which is preferably binary information, accessible to an external entity which is arranged to read the content of the memory element 436.
- This embodiment solves the problem of diagnosing a fault by open circuit. However, it generates a constant current leak.
- FIG. 5 shows schematically another preferred embodiment of the invention, which is a variant of the embodiment which has just been described in connection with the illustration of FIG. 4.
- the matrix light source 500 is intended to be voltage-controlled and comprises a plurality of elementary light sources with an electroluminescent semiconductor element 510 and a common non-illustrated substrate operatively connected to an integrated circuit 520.
- the integrated circuit 520 further comprises for at least one elementary light source 510, an open circuit fault detection circuit 530.
- the control of each elementary source, or in an equivalent manner , of each pixel is reduced to the control of a MOSFET type field effect transistor device 532.
- the elementary light source 510 can be selectively connected to the voltage source 10
- the transistor 532 is preferably characterized by a low voltage drop between its drain and source terminals. It is and controlled by a control signal 12 coming from a control unit external to the matrix light source.
- the open circuit fault detection circuit 540 further comprises a load 534 connected in parallel with the switch transistor 532.
- the load 543 comprises a second transistor as well as a resistor connected in series with the second transistor.
- the intensity of the leakage current that can flow in this branch is mainly defined by the value of the resistance.
- the second transistor, forming part of the load branch 534 may have a low voltage drop between its drain and source terminals.
- the state of the transistor 534 is controlled by a control signal 14 coming in the case illustrated by FIG. 5 from a control unit which generates it from the control signal 12 intended to control the state of the switch transistor 532.
- the control signal 12 is in this example generated by a control unit external to the matrix light source. This arrangement makes it possible to control the second, and therefore to connect the entire load 534, only in passing mode when an open-circuit fault diagnosis takes place.
- An open-circuit fault of the elementary light source 510 is detectable when the first transistor (switch) 532 is blocking, while the second transistor (load) 534 is on.
- the control unit having as input the control signal 12 which is relayed to the first switch transistor 532, and generating the control signal 14 for the second transistor of the load 543, is preferably configured to generate the signal control 14 so that the second transistor turns on when the first transistor 532 switches to its blocking state.
- the falling edge of the binary signal 12 thus coincides with the rising edge of the binary signal 14.
- Electronic circuits making it possible to carry out the functionality described for the control unit are within the reach of those skilled in the art, without however going out of the scope of the present invention.
- this control circuit is integrated into the integrated circuit 520 of the matrix light source.
- the comparison circuit 538 compares the voltage drop across the load 534 with a predetermined threshold value.
- the threshold value can for example be 0.7 V. If the voltage drop across the terminals of the load 534 is less than 0.7 V, an indication of fault detection is recorded in a memory element 536 provided for this purpose.
- This embodiment does not generate a leakage current through the load 532 only when an open-circuit fault diagnosis takes place. If this is not the case, no electrical energy is dissipated by the load.
- the integrated circuit may include other electronic circuits and / or memory elements used for other functions in relation to the matrix light source and / or with the elementary light sources. The scope of protection is determined by the claims.
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- Led Devices (AREA)
- Electroluminescent Light Sources (AREA)
- Lighting Device Outwards From Vehicle And Optical Signal (AREA)
- Circuit Arrangement For Electric Light Sources In General (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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FR1859023A FR3086724B1 (en) | 2018-09-28 | 2018-09-28 | VOLTAGE-DRIVEN MATRIX LIGHT SOURCE WITH DIAGNOSTIC CIRCUIT FOR A MOTOR VEHICLE |
PCT/EP2019/075839 WO2020064824A1 (en) | 2018-09-28 | 2019-09-25 | Voltage-controlled matrix light source with diagnostic circuit for a motor vehicle |
Publications (1)
Publication Number | Publication Date |
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EP3857665A1 true EP3857665A1 (en) | 2021-08-04 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP19773092.2A Pending EP3857665A1 (en) | 2018-09-28 | 2019-09-25 | Voltage-controlled matrix light source with diagnostic circuit for a motor vehicle |
Country Status (6)
Country | Link |
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US (1) | US11457518B2 (en) |
EP (1) | EP3857665A1 (en) |
JP (1) | JP7430712B2 (en) |
CN (1) | CN112805896A (en) |
FR (1) | FR3086724B1 (en) |
WO (1) | WO2020064824A1 (en) |
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KR20220100419A (en) * | 2021-01-08 | 2022-07-15 | 현대모비스 주식회사 | Lamp for vehicle and vehicle including the same |
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DE102008055582A1 (en) | 2008-12-23 | 2010-06-24 | Aixtron Ag | MOCVD reactor with cylindrical gas inlet member |
US9131557B2 (en) * | 2009-12-03 | 2015-09-08 | Led Net Ltd. | Efficient illumination system for legacy street lighting systems |
WO2011073096A1 (en) | 2009-12-16 | 2011-06-23 | St-Ericsson Sa | Circuit for controlling current to light-emitting diode (led) |
US8773038B2 (en) * | 2011-08-26 | 2014-07-08 | Infineon Technologies Ag | Driver circuit for efficiently driving a large number of LEDs |
JP2015026604A (en) * | 2013-06-18 | 2015-02-05 | パナソニックIpマネジメント株式会社 | Semiconductor light source driving device and projection type display device |
US10306731B2 (en) * | 2016-05-06 | 2019-05-28 | Texas Instruments Incorporated | Configurable switch array |
US9918367B1 (en) * | 2016-11-18 | 2018-03-13 | Infineon Technologies Ag | Current source regulation |
-
2018
- 2018-09-28 FR FR1859023A patent/FR3086724B1/en active Active
-
2019
- 2019-09-25 US US17/280,476 patent/US11457518B2/en active Active
- 2019-09-25 CN CN201980064251.7A patent/CN112805896A/en active Pending
- 2019-09-25 EP EP19773092.2A patent/EP3857665A1/en active Pending
- 2019-09-25 WO PCT/EP2019/075839 patent/WO2020064824A1/en unknown
- 2019-09-25 JP JP2021517271A patent/JP7430712B2/en active Active
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WO2020064824A1 (en) | 2020-04-02 |
CN112805896A (en) | 2021-05-14 |
US11457518B2 (en) | 2022-09-27 |
FR3086724B1 (en) | 2022-10-14 |
JP7430712B2 (en) | 2024-02-13 |
US20210315081A1 (en) | 2021-10-07 |
FR3086724A1 (en) | 2020-04-03 |
JP2022502820A (en) | 2022-01-11 |
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