EP0695112A1 - Circuit containing light emitting diodes - Google Patents

Circuit containing light emitting diodes Download PDF

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Publication number
EP0695112A1
EP0695112A1 EP95401760A EP95401760A EP0695112A1 EP 0695112 A1 EP0695112 A1 EP 0695112A1 EP 95401760 A EP95401760 A EP 95401760A EP 95401760 A EP95401760 A EP 95401760A EP 0695112 A1 EP0695112 A1 EP 0695112A1
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EP
European Patent Office
Prior art keywords
emitting diodes
group
series
light
voltage
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EP95401760A
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German (de)
French (fr)
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EP0695112B1 (en
Inventor
Bernard Bardy
Vincent Thouzeau
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Vibrachoc SAS
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Vibrachoc SAS
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    • 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]
    • H05B45/10—Controlling the intensity of the light

Definitions

  • the present invention relates to a circuit for mounting light-emitting diodes.
  • Light emitting diodes are used in particular for lighting display panels, keyboards, etc.
  • a mounting circuit is known in which the light-emitting diodes are grouped in series / parallel: n chains are placed in parallel each comprising p light-emitting diodes placed in series.
  • the assembly is supplied with 28 volts direct current and, for control, there is also a variable DC voltage from 0 to 28 volts.
  • This control voltage supplies an electronic circuit whose output serves to polarize the base of a transistor put in series in each chain. With this command, the luminance curve, as a function of the supply voltage, of a tube circuit is roughly reproduced.
  • the present invention provides a circuit for mounting light-emitting diodes which also allows the luminance curve to be reproduced as a function of the supply voltage of a lamp circuit, in the case where only one variable DC voltage is available.
  • the present invention thus relates to a circuit for mounting light-emitting diodes supplied between a variable DC voltage from 0 to V volts and ground, characterized in that it comprises, connected in series, a first resistor R1 and two groups of diodes light-emitting diodes connected in parallel, each group comprising at least one chain comprising P light-emitting diodes connected in series, P possibly being equal to 1, in that a second resistor R2 is furthermore arranged in series in one of the two groups, downstream of the group in the current flow direction, a third resistor R3 being arranged in series in the other group, upstream of said group and in that a diode is connected between a first point located upstream of said second resistor R2 and downstream of the group to which it belongs and a second point located downstream of the third resistor R3 and upstream of the group to which it belongs , said diode ensuring the series connection of the two groups when the voltage V2-V3 between said first point and said second point reaches the threshold voltage of said
  • FIG. 1 shows the mounting circuit according to the invention.
  • Figure 2 is a diagram equivalent to the circuit of Figure 1 during low voltage power supplies.
  • Figure 3 is the same circuit as that of Figure 1 but shown in a manner more clearly showing the series connection of the two groups of light-emitting diodes during power supplies at higher voltages, the diode being on.
  • FIG. 4 shows the luminance curve of the light-emitting diodes mounted in the circuit according to the invention as a function of the supply voltage V, compared with that of a tube circuit.
  • FIG. 5 represents a preferred embodiment of the invention.
  • This circuit therefore comprises two groups 1 and 2 of light-emitting diodes 3 placed in series in each of the two groups.
  • the two groups connected in parallel are arranged in series with a first resistance R1.
  • the circuit is supplied between ground and a variable DC voltage from 0 to 28 volts.
  • a second resistor R2 is arranged in series downstream of the light-emitting diodes 3 of group 1 (considering the direction of current flow) and a third resistor R3 is arranged in series, upstream of the light-emitting diodes 3 of group 2.
  • a diode 4 is connected between point 5 located between the last light-emitting diode 3 of group 1 and the second resistor R2 and point 6 located between the third resistor R3 and the first light-emitting diode 3 of group 2.
  • each group comprises a chain of four light-emitting diodes 3 and that the threshold voltage of light-emitting diodes 3 and of diode 4 is 2 volts.
  • the diode 4 is blocked and the circuit is equivalent to a circuit of two groups 1 and 2 connected in parallel as shown in FIG. 2.
  • the voltage at point 6 remains practically constant at 8 volts (4 x 2 volts ) as soon as the threshold voltage of the light-emitting diodes 3 is reached.
  • the intensity increases in the single chain of group 2 and the voltage drop increases across R bornes.
  • the voltage increases since the voltage drop is constant in the light-emitting diodes 3 and equal to approximately 8 volts.
  • the proposed circuit is equivalent to a circuit of two groups connected in parallel, which makes it possible to reduce the threshold voltage of each group of light-emitting diodes ( ⁇ 8 volts).
  • the diode 4 being blocked and when the supply voltage becomes higher and up to 28 volts, the circuit is equivalent to a circuit of two groups 1 and 2 in series ( Figure 3). Consumption is thus limited. Diode 4 is then on.
  • the characteristics of the luminance curve are adjusted to get as close as possible to the luminance curve of a tube circuit.
  • the curve L in FIG. 4 schematically represents the luminance curve of a tube circuit as a function of the supply voltage.
  • the curves SP and S represent the luminance curve in the case of the present invention as a function of the supply voltage: the curve SP corresponds to the phase where the diode 4 is blocked and the curve S to the phase where the diode 4 is busy.
  • resistors R1, R2 and R3 make it possible to follow more or less the curve L of a tube circuit.
  • the number P can also be equal to 1.
  • they are connected by transverse links 9 ensuring a grid of all the chains of the group.

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  • Led Devices (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

The circuit includes two groups (1,2) of LEDs (3). The group (1) has the LEDs preceding a series resistor (R2) and group (2) is preceded by a series resistor (R3). The two groups of LEDs are bridged together at points (5,6) by a forward biassed diode (4). The voltage supply is typically 0-28 V. At low supply voltages, the leds operate in parallel. When the potential difference across the diode (4) passes the bias threshold, all the leds are placed in series. The change in intensity with voltage enables the array to follow the graph for a filament lamp by suitable choice of resistance (R1, R2, R3). <IMAGE>

Description

La présente invention concerne un circuit de montage de diodes électroluminescentes.The present invention relates to a circuit for mounting light-emitting diodes.

Les diodes électroluminescentes sont utilisées notamment pour l'éclairage des panneaux de visualisation, des claviers etc.Light emitting diodes are used in particular for lighting display panels, keyboards, etc.

On connaît un circuit de montage dans lequel les diodes électroluminescentes sont groupées en série/parallèle :
   n chaînettes sont mises en parallèles comportant chacune p diodes électroluminescentes mises en série. L'ensemble est alimenté sous 28 volts en courant continu et, pour la commande, on dispose en outre d'une tension continue variable de 0 à 28 volts. Cette tension de commande alimente un circuit électronique dont la sortie sert à polariser la base d'un transistor mis en série dans chaque chaînette. Avec cette commande, on reproduit à peu près la courbe de luminance, en fonction de la tension d'alimentation, d'un circuit à lampes.A mounting circuit is known in which the light-emitting diodes are grouped in series / parallel:
n chains are placed in parallel each comprising p light-emitting diodes placed in series. The assembly is supplied with 28 volts direct current and, for control, there is also a variable DC voltage from 0 to 28 volts. This control voltage supplies an electronic circuit whose output serves to polarize the base of a transistor put in series in each chain. With this command, the luminance curve, as a function of the supply voltage, of a tube circuit is roughly reproduced.

La présente invention propose un circuit de montage de diodes électroluminescentes permettant de reproduire également la courbe de luminance en fonction de la tension d'alimentation d'un circuit à lampes, dans le cas où on ne dispose que d'une seule tension continue variable.The present invention provides a circuit for mounting light-emitting diodes which also allows the luminance curve to be reproduced as a function of the supply voltage of a lamp circuit, in the case where only one variable DC voltage is available.

La présente invention a ainsi pour objet un circuit de montage de diodes électroluminescentes alimenté entre une tension continue variable de 0 à V volts et la masse, caractérisé en ce qu'il comprend, montés en série, une première résistance R₁ et deux groupes de diodes électroluminescentes reliés en parallèle, chaque groupe comportant au-moins une chaînette comportant P diodes électroluminescentes montées en série, P pouvant être égal à 1, en ce qu'une seconde résistance R₂ est en outre disposée en série dans l'un des deux groupes, en aval du groupe dans le sens de passage du courant, une troisième résistance R₃ étant disposée en série dans l'autre groupe, en amont dudit groupe et en ce qu'une diode est reliée entre un premier point situé en amont de ladite seconde résistance R₂ et en aval du groupe auquel elle appartient et un second point situé en aval de la troisième résistance R₃ et en amont du groupe auquel elle appartient, ladite diode assurant la mise en série des deux groupes lorsque la tension V₂-V₃ entre ledit premier point et ledit deuxième point atteint la tension de seuil de ladite diode.The present invention thus relates to a circuit for mounting light-emitting diodes supplied between a variable DC voltage from 0 to V volts and ground, characterized in that it comprises, connected in series, a first resistor R₁ and two groups of diodes light-emitting diodes connected in parallel, each group comprising at least one chain comprising P light-emitting diodes connected in series, P possibly being equal to 1, in that a second resistor R₂ is furthermore arranged in series in one of the two groups, downstream of the group in the current flow direction, a third resistor R₃ being arranged in series in the other group, upstream of said group and in that a diode is connected between a first point located upstream of said second resistor R₂ and downstream of the group to which it belongs and a second point located downstream of the third resistor R₃ and upstream of the group to which it belongs , said diode ensuring the series connection of the two groups when the voltage V₂-V₃ between said first point and said second point reaches the threshold voltage of said diode.

On va maintenant donner la description d'un exemple de mise en oeuvre de l'invention en se reportant au dessin annexé dans lequel :We will now give the description of an exemplary implementation of the invention with reference to the appended drawing in which:

La figure 1 représente le circuit de montage selon l'invention.Figure 1 shows the mounting circuit according to the invention.

La figure 2 est un schéma équivalent au circuit de la figure 1 lors des alimentations à faible tension.Figure 2 is a diagram equivalent to the circuit of Figure 1 during low voltage power supplies.

La figure 3 est le même circuit que celui de la figure 1 mais représenté d'une façon montrant plus distinctement la mise en série des deux groupes de diodes électroluminescentes lors des alimentations à des plus fortes tensions, la diode étant passante.Figure 3 is the same circuit as that of Figure 1 but shown in a manner more clearly showing the series connection of the two groups of light-emitting diodes during power supplies at higher voltages, the diode being on.

La figure 4 montre la courbe de luminence des diodes électroluminescentes montées dans le circuit selon l'invention en fonction de la tension V d'alimentation, comparée à celle d'un circuit à lampes.FIG. 4 shows the luminance curve of the light-emitting diodes mounted in the circuit according to the invention as a function of the supply voltage V, compared with that of a tube circuit.

La figure 5 représente une réalisation préférée de l'invention.FIG. 5 represents a preferred embodiment of the invention.

En se référant à la figure 1, on voit ainsi un circuit d'éclairage par diodes électroluminescentes conforme à l'invention.Referring to Figure 1, there is thus seen a lighting circuit by light emitting diodes according to the invention.

Ce circuit comprend donc deux groupes 1 et 2 de diodes électroluminescentes 3 mises en série dans chacun des deux groupes. Les deux groupes, reliés en parallèles sont disposés en série avec une première résistance R₁. Le circuit est alimenté entre la masse et une tension continue variable de 0 à 28 volts. Une seconde résistance R₂ est disposée en série en aval des diodes électroluminescentes 3 du groupe 1 (en considérant le sens de passage du courant) et une troisième résistance R₃ est disposée en série, en amont des diodes électroluminescentes 3 du groupe 2.This circuit therefore comprises two groups 1 and 2 of light-emitting diodes 3 placed in series in each of the two groups. The two groups, connected in parallel are arranged in series with a first resistance R₁. The circuit is supplied between ground and a variable DC voltage from 0 to 28 volts. A second resistor R₂ is arranged in series downstream of the light-emitting diodes 3 of group 1 (considering the direction of current flow) and a third resistor R₃ is arranged in series, upstream of the light-emitting diodes 3 of group 2.

Enfin, une diode 4 est reliée entre le point 5 situé entre la dernière diode électroluminescente 3 du groupe 1 et la seconde résistance R₂ et le point 6 situé entre la troisième résistance R₃ et la première diode électroluminescente 3 du groupe 2.Finally, a diode 4 is connected between point 5 located between the last light-emitting diode 3 of group 1 and the second resistor R₂ and point 6 located between the third resistor R₃ and the first light-emitting diode 3 of group 2.

Lorsque la tension V₂-V₃ entre les points 5 et 6 atteint et dépasse la tension de seuil de la diode 4, les groupes 1 et 2 de diodes électroluminescentes 3 sont mis en série.When the voltage V₂-V₃ between points 5 and 6 reaches and exceeds the threshold voltage of the diode 4, the groups 1 and 2 of light-emitting diodes 3 are put in series.

Le fonctionnement est le suivant :The operation is as follows:

On suppose que chaque groupe comporte une chaînette de quatre diodes électroluminescentes 3 et que la tension de seuil des diodes électroluminescentes 3 et de la diode 4 est de 2 volts.It is assumed that each group comprises a chain of four light-emitting diodes 3 and that the threshold voltage of light-emitting diodes 3 and of diode 4 is 2 volts.

Aux faibles tensions d'alimentation, la diode 4 est bloquée et le circuit est équivalent à un circuit de deux groupes 1 et 2 montés en parallèle comme représenté figure 2. La tension au point 6 reste pratiquement constante à 8 volts (4 x 2 volts) dès lors que la tension de seuil des diodes électroluminescentes 3 est atteinte. Au fur et à mesure que la tension d'alimentation augmente, l'intensité croît dans l'unique chaînette du groupe 2 et la chute de tension augmente aux bornes de R₃. Au point 5, en revanche la tension croît puisque la chute de tension est constante dans les diodes électroluminescentes 3 et égale à environ 8 volts.At low supply voltages, the diode 4 is blocked and the circuit is equivalent to a circuit of two groups 1 and 2 connected in parallel as shown in FIG. 2. The voltage at point 6 remains practically constant at 8 volts (4 x 2 volts ) as soon as the threshold voltage of the light-emitting diodes 3 is reached. As the supply voltage increases, the intensity increases in the single chain of group 2 and the voltage drop increases across R bornes. At point 5, on the other hand, the voltage increases since the voltage drop is constant in the light-emitting diodes 3 and equal to approximately 8 volts.

Lors de l'augmentation de la tension d'alimentation, la chute de tension supplémentaire se produit aux bornes de la résistance R₂, la tension au point 5 augmentant.When the supply voltage increases, the additional voltage drop occurs across the resistor R₂, the voltage at point 5 increasing.

Lorsque la tension au point 5 atteint environ 10 volts on atteint la tension de seuil de la diode 4 (10 volts au point 5 moins 8 volts au point 6 soit 2 volts) et celle-ci devient passante mettant les deux groupes 1 et 2 en série comme on le voit clairement sur la figure 3.When the voltage at point 5 reaches approximately 10 volts, the threshold voltage of diode 4 is reached (10 volts at point 5 minus 8 volts at point 6, ie 2 volts) and this one turns on putting the two groups 1 and 2 in series as we can clearly see in Figure 3.

A partir de ce moment, et jusqu'à la tension d'alimentation maximale de 28 volts, la chute de tension entre les points 7 et 8 (figure 3) reste pratiquement constante et égale à environ 18 volts. Au fur et à mesure que l'intensité croît avec l'augmentation de la tension d'alimentation, la chute de tension supplémentaire est absorbée par la résistance R₁. En effet, aux bornes de R₂ et de R₃ la tension reste pratiquement constante et égale à environ 10 volts. L'intensité n'augmente pas dans R₂ et R₃ mais seulement dans la suite en série des diodes électroluminescentes 3 des groupes 1 et 2.From this moment, and up to the maximum supply voltage of 28 volts, the voltage drop between points 7 and 8 (Figure 3) remains practically constant and equal to approximately 18 volts. As the intensity increases with the increase in the supply voltage, the additional voltage drop is absorbed by the resistor R₁. Indeed, at the terminals of R₂ and R₃ the voltage remains practically constant and equal to approximately 10 volts. The intensity does not increase in R₂ and R₃ but only in the series sequence of the light-emitting diodes 3 of groups 1 and 2.

Ainsi, aux faibles tensions d'alimentation, le circuit proposé est équivalent à un circuit de deux groupes montés en parallèle, ce qui permet de réduire la tension de seuil de chaque groupe de diodes électroluminescentes (≅ 8 volts). La diode 4 étant bloquée et lorsque la tension d'alimentation devient plus élevée et jusqu'à 28 volts, le circuit est équivalent à un circuit de deux groupes 1 et 2 en série (figure 3). La consommation est ainsi limitée. La diode 4 est alors passante.Thus, at low supply voltages, the proposed circuit is equivalent to a circuit of two groups connected in parallel, which makes it possible to reduce the threshold voltage of each group of light-emitting diodes (≅ 8 volts). The diode 4 being blocked and when the supply voltage becomes higher and up to 28 volts, the circuit is equivalent to a circuit of two groups 1 and 2 in series (Figure 3). Consumption is thus limited. Diode 4 is then on.

En jouant sur les valeurs des résistances R₁, R₂, et R₃, on règle les caractéristiques de la courbe de luminance (seuil, courbure) pour se rapprocher au maximum de la courbe de luminance d'un circuit à lampes.By playing on the values of the resistances R₁, R₂, and R₃, the characteristics of the luminance curve (threshold, curvature) are adjusted to get as close as possible to the luminance curve of a tube circuit.

La courbe L de la figure 4 représente schématiquement la courbe de luminance d'un circuit à lampes en fonction de la tension d'alimentation.The curve L in FIG. 4 schematically represents the luminance curve of a tube circuit as a function of the supply voltage.

Les courbes S-P et S représentent la courbe de luminance dans le cas de la présente invention en fonction de la tension d'alimentation : la courbe S-P correspond à la phase où la diode 4 et bloquée et la courbe S à la phase où la diode 4 est passante.The curves SP and S represent the luminance curve in the case of the present invention as a function of the supply voltage: the curve SP corresponds to the phase where the diode 4 is blocked and the curve S to the phase where the diode 4 is busy.

Comme on l'a dit, le choix de la valeur des résistances R₁, R₂ et R₃ permet de suivre plus au moins la courbe L d'un circuit à lampes.As has been said, the choice of the value of resistors R₁, R₂ and R₃ makes it possible to follow more or less the curve L of a tube circuit.

Sur la figure 5 qui représente une réalisation préférée, chaque groupe 1 et 2 de diodes électroluminescentes 3 est constitué de n (ici n=3) chaînettes de diodes électroluminescentes 3 mises en parallèles.In FIG. 5 which represents a preferred embodiment, each group 1 and 2 of light-emitting diodes 3 consists of n (here n = 3) chains of light-emitting diodes 3 placed in parallel.

Chaque chaînette comporte P (ici P=4) diodes électroluminescentes mises en série. Le nombre P peut d'ailleurs être égal à 1. En outre, de préférence, afin d'assurer l'alimentation d'une chaînette en cas de défaillance de l'une des diodes électroluminescentes d'une chaînette, elles sont reliées par des liaisons transversales 9 assurant un quadrillage de l'ensemble des chaînettes du groupe.Each chain comprises P (here P = 4) light-emitting diodes placed in series. The number P can also be equal to 1. In addition, preferably, in order to ensure the supply of a chain in the event of failure of one of the light-emitting diodes of a chain, they are connected by transverse links 9 ensuring a grid of all the chains of the group.

Claims (2)

1) Circuit de montage de diodes électroluminescentes (3) alimenté entre une tension continue variable de 0 à V volts et la masse, caractérisé en ce qu'il comprend, montés en série, une première résistance R₁ et deux groupes (1, 2) de diodes électroluminescentes reliés en parallèle, chaque groupe comportant au-moins une chaînette comportant P diodes électroluminescentes (3) montées en série, P pouvant être égal à 1, en ce qu'une seconde résistance R₂ est en outre disposée en série dans l'un des deux groupes, en aval du groupe dans le sens de passage du courant, une troisième résistance R₃ étant disposée en série dans l'autre groupe, en amont dudit groupe et en ce qu'une diode (4) est reliée entre un premier point (5) situé en amont de ladite seconde résistance R₂ et en aval du groupe auquel elle appartient et un second point (6) situé en aval de la troisième résistance R₃ et en amont du groupe auquel elle appartient, ladite diode (4) assurant la mise en série des deux groupes (1, 2) lorsque la tension V₂-V₃ entre ledit premier point (5) et ledit deuxième point (6) atteint la tension de seuil de ladite diode (4). 1) circuit for mounting light-emitting diodes (3) supplied between a variable DC voltage from 0 to V volts and ground, characterized in that it comprises, connected in series, a first resistor R₁ and two groups (1, 2) of light-emitting diodes connected in parallel, each group comprising at least one chain comprising P light-emitting diodes (3) connected in series, P possibly being equal to 1, in that a second resistor R₂ is furthermore arranged in series in the one of the two groups, downstream of the group in the direction of current flow, a third resistor R₃ being arranged in series in the other group, upstream of said group and in that a diode (4) is connected between a first point (5) located upstream of said second resistor R₂ and downstream of the group to which it belongs and a second point (6) located downstream of the third resistor R₃ and upstream of the group to which it belongs, said diode (4) ensuring l a series of the two groups (1, 2) when the voltage V₂-V₃ between said first point (5) and said second point (6) reaches the threshold voltage of said diode (4). 2) Circuit de montage selon la revendication 1, caractérisé en ce que chaque groupe comporte n dites chaînettes reliées en parallèle. 2) assembly circuit according to claim 1, characterized in that each group comprises n said chains connected in parallel.
EP95401760A 1994-07-29 1995-07-25 Circuit containing light emitting diodes Expired - Lifetime EP0695112B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9409429 1994-07-29
FR9409429A FR2723286B1 (en) 1994-07-29 1994-07-29 LIGHT EMITTING DIODE MOUNTING CIRCUIT

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EP0695112A1 true EP0695112A1 (en) 1996-01-31
EP0695112B1 EP0695112B1 (en) 1999-10-13

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FR2745458A1 (en) * 1996-02-28 1997-08-29 Valeo Electronique IMPROVEMENT ON ILLUMINATION CIRCUITS WITH LIGHT EMITTING DIODES, PARTICULARLY FOR MOTOR VEHICLES, SIGNALING LIGHT AND CONTROL PANEL INCORPORATING THE SAME
WO2002028147A1 (en) * 2000-09-29 2002-04-04 Thales Control device for illuminating means
WO2002028148A2 (en) * 2000-09-29 2002-04-04 Aerospace Optics, Inc. Enhanced trim resolution voltage-controlled dimming led driver
FR2821520A1 (en) * 2001-02-23 2002-08-30 Thomson Csf Device for luminosity control of light-emitting diodes, by providing control voltage proportional to square of differential between consigned voltaage and constant voltage
US6489728B2 (en) 2000-09-29 2002-12-03 Aerospace Optics, Inc. Power efficient LED driver quiescent current limiting circuit configuration
US6650064B2 (en) 2000-09-29 2003-11-18 Aerospace Optics, Inc. Fault tolerant led display design
US6653798B2 (en) 2000-09-29 2003-11-25 Aerospace Optics, Inc. Voltage dimmable LED display producing multiple colors
WO2007129131A1 (en) * 2006-05-10 2007-11-15 Nokia Corporation Apparatus having supply voltage adaptive light emitting component circuitry country and method of controlling
WO2010013173A2 (en) * 2008-07-30 2010-02-04 Philips Intellectual Property & Standards Gmbh Device with light-emitting diode circuits
WO2010038190A1 (en) * 2008-10-02 2010-04-08 Philips Intellectual Property & Standards Gmbh Led circuit arrangement with improved flicker performance
US7906915B2 (en) 2008-04-19 2011-03-15 Aerospace Optics, Inc. Enhanced trim resolution voltage-controlled dimming LED driving circuit
US9000676B2 (en) 2010-10-19 2015-04-07 Koninklijke Philips N.V. LED circuit arrangement
WO2020035436A1 (en) * 2018-08-17 2020-02-20 Signify Holding B.V. Led driving circuit

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US6885035B2 (en) * 1999-12-22 2005-04-26 Lumileds Lighting U.S., Llc Multi-chip semiconductor LED assembly
DE10032840A1 (en) * 2000-07-06 2002-01-17 Sick Ag Optoelectronic sensor
DE102006029957A1 (en) * 2006-06-29 2008-01-03 Osram Opto Semiconductors Gmbh lighting device

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Cited By (34)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2745458A1 (en) * 1996-02-28 1997-08-29 Valeo Electronique IMPROVEMENT ON ILLUMINATION CIRCUITS WITH LIGHT EMITTING DIODES, PARTICULARLY FOR MOTOR VEHICLES, SIGNALING LIGHT AND CONTROL PANEL INCORPORATING THE SAME
EP0793403A1 (en) * 1996-02-28 1997-09-03 Valeo Electronique Improvement in LED circuits, especially for vehicles, signalisation lights and control panels
US6653798B2 (en) 2000-09-29 2003-11-25 Aerospace Optics, Inc. Voltage dimmable LED display producing multiple colors
US6670776B2 (en) 2000-09-29 2003-12-30 Aerospace Optics, Inc. Enhanced trim resolution voltage-controlled dimming LED driver
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Also Published As

Publication number Publication date
DE69512720D1 (en) 1999-11-18
FR2723286B1 (en) 1996-09-13
EP0695112B1 (en) 1999-10-13
FR2723286A1 (en) 1996-02-02
DE69512720T2 (en) 2000-06-08

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