EP1701589B1 - Schaltung und Verfahren zum Überwachen der Temperatur einer Leuchtdiode - Google Patents

Schaltung und Verfahren zum Überwachen der Temperatur einer Leuchtdiode Download PDF

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Publication number
EP1701589B1
EP1701589B1 EP05005054A EP05005054A EP1701589B1 EP 1701589 B1 EP1701589 B1 EP 1701589B1 EP 05005054 A EP05005054 A EP 05005054A EP 05005054 A EP05005054 A EP 05005054A EP 1701589 B1 EP1701589 B1 EP 1701589B1
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EP
European Patent Office
Prior art keywords
light emitting
emitting diode
dependency
forward voltage
temperature
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EP05005054A
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English (en)
French (fr)
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EP1701589A1 (de
Inventor
Gunnar Klinghult
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Sony Mobile Communications AB
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Sony Ericsson Mobile Communications AB
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Priority to EP05005054A priority Critical patent/EP1701589B1/de
Priority to DE602005009317T priority patent/DE602005009317D1/de
Priority to AT05005054T priority patent/ATE406783T1/de
Priority to PCT/EP2006/001102 priority patent/WO2006094590A1/en
Publication of EP1701589A1 publication Critical patent/EP1701589A1/de
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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]
    • H05B45/20—Controlling the colour of the light
    • H05B45/22—Controlling the colour of the light using optical feedback
    • 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
    • H05B45/12—Controlling the intensity of the light using optical feedback
    • 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
    • H05B45/56—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits involving measures to prevent abnormal temperature of the 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]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • H05B45/38—Switched mode power supply [SMPS] using boost topology

Definitions

  • the invention relates to an electronic circuit and method for monitoring a temperature of a light emitting diode that is driven in a constant-current mode.
  • light emitting diodes are used for lightening applications, e. g. as flash lights, background lights for displays or for lightening keys, etc..
  • light emitting diodes are small size, low power consumption, high reliability and low heat generation in comparison to ordinary incandescent lamps.
  • white light emitting diodes are used.
  • Fig. 6 shows a solution according to the prior art frequently integrated into mobile phones.
  • a light emitting diode 62 is driven by a drive circuit 61.
  • the drive circuit 61 is connected to both a power supply 63 and the light emitting diode 62 and provides a constant current to the light emitting diode.
  • the current supplied to the light emitting diode 62 is maintained constant to guarantee a constant brightness of the light emitting diode 62 during operation.
  • a thermistor 64 is located as close as possible to the light emitting diode 62.
  • the thermistor 64 is a resistant whose resistance changes proportional to the temperature of the thermistor.
  • the thermistor is a temperature sensor. Therefore, the thermistor 64 is adapted to measure the temperature in an area surrounding the thermistor 64 and thus the temperature of the light emitting diode 62.
  • the thermistor 64 is connected to a microprocessor 65 for controlling the thermistor 64. Based on an output of the thermistor 64 the microprocessor 65 calculates a current temperature of the light emitting diode 62.
  • the thermistor 64 cannot exactly measure the temperature of the light emitting diode 62, since a sensing point of the thermistor 64 is not integrated into the light emitting diode 62. As it takes some time for the heat generated by the light emitting diode 62 to spread to the sensing point of the thermistor 64, a time delay with respect to the temperature measured by the thermistor 64 is inevitable.
  • the thermistor is an additional element that has to be integrated to the mobile electronic equipment and has to be provided with energy.
  • both energy and space are usually very limited.
  • EP-A-1 044 858 discloses a method for determining correction factors to compensate for a drift in LED luminosity due to temperature shifts, whereby the actual compensation factors are determined by measuring the forward voltage at a constant current, but different temperatures and LED luminosity.
  • Unites States Patent Application Publication [ US 2004/052076 A1 ] discloses controlled lighting methods and apparatus, whereby the light source is outputting radiation at a calibrated intensity that substantially corresponds in a predetermined manner to a control signal coming from a variety of sensors that generate one or more signals in response to some stimulus like temperature or infrared light.
  • United States Patent [ US-B1-6 807 202 ] discloses a process for stabilizing the optical output power of light-emitting diodes and laser modes.
  • a circuit for a light emitting diode or a laser diode is provided such that the changes in electrical behavior caused by the temperature lead to a temperature-independence of its optical output power.
  • US-A-6 144 165 discloses an organic electroluminescent device to form a light-emitting diode (LED), which supplies a photocurrent, which is an indication of the quantity of incident light. Said photocurrent is measured and its value is used to calculate the correct forward voltage to be set in order to obtain the desired display luminosity in consideration of the ambient light level.
  • LED light-emitting diode
  • the above object is achieved by a method for monitoring a temperature of a light emitting diode that is driven in a constant-current mode, the method comprising the following steps:
  • the present invention bases on the principle that the forward voltage of a light emitting diode in a constant-current mode is approximately inverse proportional to the temperature of the light emitting diode.
  • the forward voltage of the light emitting diode is directly related to the current temperature status of said light emitting diode, there is no time delay between a temperature variation of the light emitting diode and a variation of the forward voltage.
  • the inventive method provides a very quick, easy and reliable way to monitor a temperature of a light emitting diode.
  • the step of detecting a dependency between the forward voltage of the light emitting diode in said constant-current mode and the temperature of the light emitting diode comprises the steps of
  • the forward voltage of a light emitting diode is approximately inverse proportional to the temperature of the light emitting diode, normally it is sufficient to measure the actual forward voltage of the light emitting diode in said constant-current mode at at least two different temperatures to calculate a linearised dependency between the forward voltage of the light emitting diode in said constant-current mode and the temperature of the light emitting diode.
  • calibration to a certain individual light emitting diode can be performed in a very easy way by only two measurements.
  • heating of the light emitting diode preferably is performed by the light emitting diode itself by simply using said light emitting diode in a constant-current mode.
  • the step of detecting a dependency between the forward voltage of the light emitting diode in said constant-current mode and the temperature of the light emitting diode comprises the steps of
  • heating of the light emitting diode preferably is performed by the light emitting diode itself by simply using said light emitting diode in a constant-current mode.
  • said heat might be provided by a separate heater.
  • the temperature curve inclination for a certain identified type of light emitting diode is known.
  • Said temperature curve inclination for a certain type of light emitting diode might be determined and provided by manufacturers of light emitting diodes, for example.
  • the linearised dependency between the forward voltage of the light emitting diode in said constant-current mode and the temperature of the light emitting diode is calculated by adjusting the position of the known temperature curve inclination for the identified type of light emitting diode in a temperature / forward voltage diagram according to the measured actual forward voltage at said known temperature. Since the above described calibration requires one measurement step, only, it is very quick and cheap.
  • heating of the light emitting diode preferably is performed by the light emitting diode itself by simply using said light emitting diode in a constant-current mode.
  • said heat might be provided by a separate heater.
  • the step of measuring the actual forward voltage of the light emitting diode in said constant-current mode is performed by supplying a current that is at least 10%, preferably at least 20%, more preferably at least 40 % and most preferably at least 60 % lower than nominal current of the light emitting diode to the light emitting diode.
  • the general dependency between the forward voltage of the light emitting diode in said constant-current mode at nominal current can be calculated by using the above calibration process and general characteristics of the light emitting diodes with ease.
  • the method further comprises the step of storing said calculated linearised dependency and / or said generated dependency table as a stored dependency, wherein said stored dependency further is used as detected general dependency for calculating the actual temperature of the light emitting diode.
  • the calibration process has to be performed only once for an individual light emitting diode.
  • the above embodiment bases on the principal that light emitting diodes are light sensitive elements. Therefore, light emitting diodes can be used as light sensors when not connected to a voltage source. Consequently, in an open-circuit mode, a light emitting diode generates a small voltage proportional to the light intensity irradiating the light emitting diode.
  • the light emitting diode can be used as an ambient light sensor, e. g. for adjusting the intensity of light emitted by the light emitting diode in a very easy way. This can be performed e. g. when the light emitting diode is not in use or between two flash pulses of the light emitting diode.
  • the step of detecting a light dependency between the forward voltage of the light emitting diode in said open-circuit mode and ambient light irradiating the light emitting diode comprises the steps of
  • the method further comprises the step of storing said calculated linearised light dependency and / or said generated light dependency table as a stored light dependency, wherein said stored light dependency further is used as detected light dependency for calculating the amount of ambient light actually hitting the light emitting diode.
  • a computer program product directly loadable into the internal memory of a digital computer, comprising software code portions for performing the steps of one of the claims 1 to 8 when said product is run on a computer.
  • an electric circuit for monitoring a temperature of a light emitting diode in a constant-current mode comprising
  • the inventive electric circuit calculates the actual temperature of the light emitting diode by using the stored general dependency and the measured actual forward voltage, the temperature of the light emitting diode is monitored with high velocity, accuracy and reliability. Furthermore, as no additional elements such as thermistors are necessary to sense the temperature of the light emitting diode, the inventive electric circuit has a very easy and compact structure.
  • the electric circuit further comprises a calibrator, said calibrator being adapted to control the voltage sensor in a way that the voltage sensor sequentially measures the actual forward voltage of the light emitting diode in said constant-current mode at different temperatures, to calculate a linearised dependency and / or a dependency table between the forward voltage of the light emitting diode in said constant-current mode and the temperature of the light emitting diode by using the measured actual forward voltages at said different temperatures and to store said calculated linearised dependency and / or said generated dependency table as said dependency in said storage.
  • a calibrator being adapted to control the voltage sensor in a way that the voltage sensor sequentially measures the actual forward voltage of the light emitting diode in said constant-current mode at different temperatures, to calculate a linearised dependency and / or a dependency table between the forward voltage of the light emitting diode in said constant-current mode and the temperature of the light emitting diode by using the measured actual forward voltages at said different temperatures and to store said calculated linearised dependency and / or said generated dependency table as said
  • calibration of the inventive electric circuit for monitoring a temperature of a light emitting diode to an individual light emitting diode can be performed with ease.
  • Dependent on the requirements and on accuracy either a linearised dependency by using at least two measured actual forward voltages of the light emitting diode in said constant-current mode at different temperatures or a detailed dependency table can be used. Since, said linearised dependency and /or said dependency table are stored in said storage, quick access to said dependency is guaranteed during the operation of the inventive electric circuit.
  • said calibration has to be performed only once for an individual light emitting diode.
  • the electric circuit further comprises a calibrator, said calibrator being adapted to control the voltage sensor in a way that the voltage sensor measures the actual forward voltage of the light emitting diode in said constant-current mode at a known temperature, to identify a type of the light emitting diode, to calculate a linearised dependency between the forward voltage of the light emitting diode in said constant-current mode and the temperature of the light emitting diode by using the measured actual forward voltage at said known temperature and a predefined temperature curve inclination for the identified type of light emitting diode and to store said calculated linearised dependency as said dependency in said storage.
  • a calibrator being adapted to control the voltage sensor in a way that the voltage sensor measures the actual forward voltage of the light emitting diode in said constant-current mode at a known temperature, to identify a type of the light emitting diode, to calculate a linearised dependency between the forward voltage of the light emitting diode in said constant-current mode and the temperature of the light emitting diode by using the measured actual forward
  • the calibrator is further adapted to control the driver circuit in a way that a current that is at least 10%, preferably at least 20%, more preferably at least 40% and most preferably at least 60% lower than nominal current of the light emitting diode is supplied to the light emitting diode in said constant-current mode during operation of said calibrator.
  • the calibrator of the inventive electric circuit is a adapted to control the driver circuit in a way that a current that is lower than nominal current of the light emitting diode is supplied to the light emitting diode in said constant-current mode during the operation of said calibrator, it is ensured that the light emitting diode is not damaged during calibration.
  • the corresponding linearised dependency and / or dependency table for the light emitting diode at nominal current can easily be calculated by using the measurement results of the calibrator.
  • the driver circuit of the inventive electric circuit is further adapted to run the light emitting diode in an open-circuit mode, it is possible to use the light emitting diode as an ambient light sensor.
  • the inventive electric circuit can be further used to adjust e. g. the intensity of light emitted by the light emitting diode.
  • said calibrator is further adapted to control the voltage sensor in a way that the voltage sensor sequentially measures the actual forward voltage of the light emitting diode in said open-circuit mode at different intensities of ambient light irradiating the light emitting diode, to calculate a linearised light dependency and / or generate a light dependency table between the forward voltage of the light emitting diode in said open-circuit mode and the intensity of ambient light irradiating the light emitting diode by using said measured actual forward voltage at said different intensities of ambient light and to store said calculated linearised light dependency and / or said generated light dependency table as said light dependency in said storage.
  • the circuit is comprised in a portable radio communication equipment.
  • the inventive electric circuit Since the inventive electric circuit has a very compact and reliable structure, it is adapted to be implemented into a portable electronic equipment and especially a portable radio communication equipment like a mobile phone. In this respect, monitoring of the temperature of light emitting diodes used in a portable electronic equipment is very important, since said equipments frequently have a rather complex structure that is heat sensitive and prevents air circulation. Thus, these equipments are prone to heat accumulation.
  • the term 'portable radio communication equipment' which herein after is referred to as a mobile radio terminal, includes all equipments such as mobile telephones, pagers, communicators, i. e. electronic organisers, smart phones or the like.
  • Fig. 1A shows a flow diagram of a preferred embodiment of the inventive method for monitoring a temperature of a light emitting diode.
  • a general dependency between a forward voltage of a light emitting diode in a constant-current mode and a temperature of the light emitting diode is detected. This step will be explained in more detail by reference to Figs. 1B and 1C , respectively.
  • step S12 said light emitting diode is driven in said constant-current mode during ordinary operation of the light emitting diode to produce light.
  • the actual forward voltage of a light emitting diode in said constant-current mode is measured in step S13.
  • This measurement preferably is performed continuously. Alternatively a regular measurement at a predefined or variable time interval might be performed.
  • the actual temperature of the light emitting diode is continuously or regularly calculated in step S14 by using the detected general dependency and the measured actual forward voltage.
  • the calculation step S14 preferably is closely linked to the measurement step S13.
  • the steps S12 to S14 are repeated as long as the light emitting diode is in a constant-current mode.
  • step S11 of detecting a general dependency between a forward voltage of a light emitting diode in a constant-current mode and a temperature of the light emitting diode are explained by reference to Figs. 1B and 1C , respectively.
  • a constant current that is at least 10 %, preferably at least 20 % , more preferably at least 40 % and most preferably at least 60 % lower than nominal current of the light emitting diode is supplied to the light emitting diode.
  • the reason is that the risk of damaging the light emitting diode during calibration of the light emitting diode because of too high temperatures is significantly reduced by providing a lower current.
  • the light emitting diode is driven in a constant-current mode.
  • step S112 the light emitting diode is sequentially heated to a plurality of different temperatures by driving the light emitting diode in said constant-current mode. Since the light emitting diode generates heat during the production of light the light emitting diode is heated.
  • an external heater might be used to heat the light emitting diode.
  • step S113 the actual forward voltage of the light emitting diode that is driven in said constant-current mode is measured at said different temperatures.
  • an actual forward voltage of the respective light emitting diode for a respective temperature is obtained.
  • the actual temperature of the light emitting diode might be measured by any suitable temperature sensor.
  • step S114 a linearised dependency between the forward voltage of the light emitting diode in said constant-current mode and the temperature of the light emitting diode is calculated by using the measured actual forward voltage at said different temperatures.
  • a linearised dependency between the forward voltage of the light emitting diode in said constant-current mode and the temperature of the light emitting diode is calculated by using the measured actual forward voltage at said different temperatures.
  • only two pairs of measured actual forward voltage and temperature values have to be provided for calculating said linearised dependency in order to obtain a good estimate.
  • the reason is that the forward voltage of a light emitting diode is approximately inverse proportional to the temperature of the light emitting diode.
  • a dependency table between the forward voltage of the light emitting diode in said constant-current mode and the temperature of the light emitting diode can be generated in step S115 by using said measured actual forward voltages at said different temperatures.
  • steps S114 and S115 can be performed alternatively or complementary.
  • a constant current that is at least 10%, preferably at least 20%, more preferably at least 40 % and most preferably at least 60% lower than nominal current of the light emitting diode is supplied to the light emitting diode.
  • step 112' the light emitting diode is heated to a known temperature.
  • step S113' the actual forward voltage of the light emitting diode in said constant-current mode at said known temperature is measured.
  • step S114' a type of the light emitting diode currently used is identified. This can either be performed automatically by measuring certain component characteristics of the light emitting diode or based on a manual user input. Step S114' might be performed either before, in parallel or after steps S111', S112' and S113'.
  • step S115' a linearised dependency between the forward voltage of the light emitting diode in said constant-current mode and the temperature of the light emitting diode is calculated by using the measured actual forward voltage at said known temperature and a predefined temperature curve inclination for the identified type of light emitting diode.
  • step S 117 S 117' as detected general dependency for calculating the actual temperature of the light emitting diode in step S 14.
  • steps S11 and S111 to S 117 and S111' to S 117' have to be performed only once for calibrating the general dependency for an individual light emitting diode or a type of light emitting diodes.
  • the reason is that the dependency of the forward voltage of a light emitting diode in a constant-current mode and the temperature spreads between different individual light emitting diodes of different types.
  • the dependency of the forward voltage of a light emitting diode in a constant-current mode and the temperature might even spread between different individual light emitting diodes of the same types. This is accounted for by the calibration methods explained by reference to Figs. 1B and 1C , respectively.
  • the inventive method provides a very quick, easy and reliable way to monitor a temperature of a light emitting diode.
  • a general light dependency between a forward voltage of a light emitting diode in an open-circuit mode and ambient light irradiating the light emitting diode is detected. This detection will be further explained by reference to Fig. 2B .
  • step S22 said light emitting diode is driven in said open-circuit mode.
  • step S23 the actual forward voltage of the light emitting diode in said open-circuit mode is measured.
  • the steps S22 to S24 are repeated as long as the light emitting diode is driven in said open-circuit mode and as long as a sensing of ambient light irradiating the light emitting diode is required.
  • step S21 of detecting a general light dependency between a forward voltage of a light emitting diode in an open-circuit mode and ambient light irradiating the light emitting diode is further explained by reference to Fig. 2B .
  • a first step S211 said light emitting diode is driven in said open-circuit mode. Thus, no external voltage is applied to the light emitting diode.
  • the light emitting diode is sequentially irradiated with different intensities of ambient light in step S212.
  • the intensity of the irradiating light is known (either due to external measurement or due to a detailed knowledge of the light source).
  • step S213 the actual forward voltage of the light emitting diode driven in said open-circuit mode is measured at different intensities of ambient light.
  • the steps S212 and S213 are repeated until sufficient numbers of pairs of measured actual forward voltages and corresponding intensities of irradiating ambient light are provided.
  • a linearised light dependency is calculated and / or a light dependency table is generated.
  • Both the linearised light dependency and the light dependency table relate to the dependency between the forward voltage of the light emitting diode in said open-circuit mode and the intensities of ambient light irradiating the light emitting diode. Both are provided by using said measured actual forward voltages at said different intensities of ambient light. While for the calculation of the linearised light dependency only two pairs of measured actual forward voltage and corresponding intensity of irradiating ambient light are necessary, the accuracy can be increased by using a higher number of pairs in a light dependency table.
  • both said calculated linearised light dependency and / or said generated light dependency table are stored as a stored light dependency in step S215.
  • step S216 is used in step S216 as detected general light dependency for calculating the amount of ambient light actually hitting the light emitting diode.
  • the calibration method described with reference to Fig. 2B above has to be performed only once for an individual diode or type of diodes.
  • the light emitting diode can be used as an ambient light sensor, e. g. for adjusting the intensity of light emitted by the light emitting diode in a constant-current mode in a very easy way. This can be performed e. g. when the light emitting diode is not in use or between two flash pulses of the light emitting diode.
  • Fig. 3 is a diagram showing the general dependency between the forward voltage of three light emitting diodes D1, D2 and D3 in a constant-current mode and the temperature of the light emitting diodes D1, D2 and D3.
  • Said diagram can be generated either by measuring a forward voltage value for each temperature value or by calculating a linearised dependency between the forward voltage of the light emitting diodes D1, D2, D3 in said constant-current mode and the temperature of the light emitting diodes D1, D2 and D3 by using two pairs of forward voltage T D11 , T D12 ; T D21 , T D22 ; and T D31 , T D32 , respectively.
  • D1, D2 and D3 either can characterise different types of diodes or different individual light emitting diodes of one type.
  • Fig. 3 the dependency described with respect to Fig. 3 is not limited to single light emitting diodes but is also applicable to several light emitting diodes connected in parallel or in series. In this case, the average temperature of the diodes would be monitored.
  • Fig. 4 a preferred embodiment of an electronic circuit for monitoring a temperature of a light emitting diode according to the present invention is described. Said electronic circuit is adapted to perform the above-described inventive method of monitoring the temperature of a light emitting diode.
  • the electronic circuit 1 is connected to a power supply 8 (in the present case a battery) and a light emitting diode 2 whose temperature has to be monitored.
  • a power supply 8 in the present case a battery
  • a light emitting diode 2 is a conventional diode for white light.
  • said diode 2 could be a laser diode or a colour diode, for example. It is obvious that said light emitting diode 2 can be a single diode or several light emitting diodes connected in parallel or in series.
  • the electronic circuit 1 comprises a driver circuit 3, a storage 4, a voltage sensor 5, a calculator 6 and a calibrator 7.
  • the driver circuit 3 is adapted to supply a predefined constant current to the light emitting diode 2 to run the light emitting diode 2 in a constant-current mode.
  • the driver circuit contains a voltage step-up converter to ensure that a constant current is applied to the diode 2 by correspondingly adapting the voltage applied to the diode 2.
  • the driver circuit 3 is adapted to run the light emitting diode 2 in an open-circuit mode and thus not to apply external voltage to the light emitting diode 2.
  • the light emitting diode 2 can be driven either in the open-circuit mode or in the constant-current mode.
  • the storage 4 stores a general dependency between a forward voltage of the light emitting diode 2 in said constant-current mode and the temperature of the light emitting diode 2.
  • the storage 4 further stores a general light dependency between the forward voltage of the light emitting diode 2 in an open-circuit mode and ambient light irradiating the light emitting diode 2.
  • the storage 4 is an EPROM and thus a non-volatile memory. Alternatively any other non-volatile memory might be used.
  • the voltage sensor 5 is adapted to measure an actual forward voltage of said light emitting diode 2, wherein said diode 2 is driven either in the constant-current mode or in the open-circuit mode.
  • the voltage sensor 5 uses a differential amplifier for measuring the actual forward voltage and comprises an A/D converter to digitise the measured value.
  • the calculator 6 is a microprocessor adapted to calculate the actual temperature of the light emitting diode 2 by using the detected general dependency and the measured actual forward voltage when the diode is driven in said constant-current mode. Moreover, in the present example, the calculator 6 is adapted to calculate an amount of ambient light actually irradiating the light emitting diode 2 by using the general light dependency and the measured actual forward voltage.
  • the calibrator 7 is adapted to control the voltage sensor 5 in a way that the voltage sensor 5 sequentially measures the actual forward voltage of the light emitting diode 2 in said constant-current mode at different temperatures.
  • the calibrator 7 is further adapted to control the driver circuit in a way that a current that is at least 10 % , preferably at least 20 % , more preferably at least 40% and most preferably at least 60% lower than nominal current of the light emitting diode 2 is supplied to the light emitting diode 2 in said constant-current mode during the operation of said calibrator 7.
  • the different temperatures of the light emitting diode 2 are achieved by a self-heating effect of the light emitting diode 2, due to the operation of the light emitting diode 2.
  • the light emitting diode 2 might be heated by using an external heater not shown in the figure.
  • the temperature of the light emitting diode 2 is measured by using an external temperature sensor (not shown in Fig. 4 ).
  • the calibrator 7 Based on the corrected actual forward voltages at said different temperatures, the calibrator 7 automatically calculates a dependency table between the forward voltage of the light emitting diode 2 in said constant-current mode and the temperature of the light emitting diode 2.
  • a dependency table is shown in Fig. 5A .
  • Fig. 5A the upper line indicates the measured actual forward voltage of said light emitting diode, and the lower line indicates the corresponding temperature value.
  • the calibrator 7 can calculate a linearised dependency as shown in Fig. 3 by simply using two pairs of voltage / temperature values for the light emitting diode 2.
  • said calibrator 7 is adapted to control the voltage sensor 5 in a way that the voltage sensor 5 measures the actual forward voltage of the light emitting diode 2 in said constant-current mode only at one known temperature.
  • the calibrator 7 automatically identifies a type of the light emitting diode 2 by measuring component characteristics of the light emitting diode 2.
  • said light emitting diode might be identified based on a manual user input.
  • a linearised dependency between the forward voltage of the light emitting diode 2 in said constant-current mode and the temperature of the light emitting diode 2 automatically is calculated by said calibrator 7 by using the measured actual forward voltage at said known temperature and a predefined temperature curve inclination for the identified type of light emitting diode 2.
  • predefined temperature curve inclinations for different types of light emitting diodes 2 preferably are stored in the storage 4 of the electronic circuit 1.
  • said predefined temperature curve inclination might be input by a user.
  • Said calculated linearised dependency and / or said generated dependency table according to all embodiments is automatically stored by said calibrator 7 as a general dependency in said storage 4.
  • said calibrator 7 is further adapted to control the driver circuit in a way that the light emitting diode 2 is driven in an open-circuit mode. Thus, no external voltage is applied on the diode 2.
  • the calibrator 7 controls the voltage sensor 5 in a way that the voltage sensor 5 sequentially measures said actual forward voltage of the light emitting diode 2 in said open-circuit mode at different intensities of ambient light irradiating the light emitting diode 2.
  • a certain amount of ambient light has to be irradiated on the light emitting diode 2 in some way by using a light source not shown in the figures.
  • said calibrator 7 preferably is adapted to calculate a linearised light dependency similar to the dependency shown in Fig. 3 but with the light intensity at the horizontal axis (x-axis) and / or to generate a light dependency table relating to the dependency between the forward voltage of the light emitting diode 2 in said open-circuit mode and the intensity of ambient light irradiating the light emitting diode 2 by using said measured actual forward voltage at said different intensities of ambient light.
  • a light dependency table is shown in Fig. 5B .
  • the upper line indicates the measured actual forward voltage of said light emitting diode
  • the lower line indicates the illuminance irradiating the light emitting diode.
  • said calculated linearised light dependency and / or said generated light dependency table are automatically stored by said calibrator 7 as said general light dependency in said storage 4.
  • said calculator 6 uses said general dependency stored in said storage 4 to automatically calculate the actual temperature of a light emitting diode 2 in real time by using the actual forward voltage measured by said voltage sensor 5.
  • the inventive electric circuit 1 is adapted to reliably monitor a temperature of the light emitting diode with ease and high accuracy in real-time.
  • the calculator 6 uses said general light dependency stored in the storage 4 for calculating an amount of ambient light actually irradiating the light emitting diode 2 by using the actual forward voltage measured by said voltage sensor 5.
  • the inventive electronic circuit 1 is adapted to monitor ambient light irradiating the light emitting diode driven in an open-circuit mode.
  • the inventive electronic circuit 1 can be used for adjusting the light intensity of the light emitting diode 2, for example.
  • the light emitting diode usually is in an open-circuit mode when it is switched off or between two flash points when the light emitting diode is used as a flasher.
  • the inventive electric circuit provides a further benefit without any extra costs or additional elements.
  • All elements of the inventive electric circuit 1 can be integrated into a circuit necessary to drive the light emitting diode 2. Thus, no additional components are needed.
  • the inventive electric circuit 1 is ideally suited to be used in portable radio communications equipments such as mobile phones. In this respect it is an advantage that the inventive electric circuit measures the temperature of the light emitting diode without a time delay and thus in real-time.

Claims (15)

  1. Verfahren zur Überwachung einer Temperatur einer im Konstantstrombetrieb betriebenen Leuchtdiode, welches die folgenden Schritte aufweist:
    - (S 11) Erfassung einer Abhängigkeit zwischen einer Vorwärtsspannung der Leuchtdiode im Konstantstrombetrieb und ihrer Temperatur;
    - (S13) Messung der momentanen Vorwärtsspannung der Leuchtdiode im Konstantstrombetrieb;
    - (S14) Berechnung der momentanen Temperatur der Leuchtdiode mittels der erfassten Abhängigkeit und der gemessenen momentanen Vorwärtsspannung; und
    welches gekennzeichnet ist durch folgende weitere Schritte:
    - (S21) Erfassung einer Lichtabhängigkeit zwischen der Vorwärtsspannung der Leuchtdiode im Leerlauf und dem Umgebungslicht, dem die Leuchtdiode ausgesetzt ist;
    - (S13) Messung der momentanen Vorwärtsspannung der Leuchtdiode im Leerlauf;
    - (S14) Berechnung der momentanen Stärke des Umgebungslichts, dem die Leuchtdiode ausgesetzt ist, mittels der erfassten Lichtabhängigkeit und der gemessenen momentanen Vorwärtsspannung.
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass der Schritt (S11) der Erfassung einer Abhängigkeit zwischen einer Vorwärtsspannung der Leuchtdiode im Konstantstrombetrieb und ihrer Temperatur folgende Schritte aufweist:
    - Erwärmung der Leuchtdiode auf eine erste Temperatur;
    - Messung der momentanen Vorwärtsspannung der Leuchtdiode im Konstantstrombetrieb bei dieser ersten Temperatur;
    - Erwärmung der Leuchtdiode auf mindestens eine zweite, von der ersten abweichende Temperatur;
    - Messung der momentanen Vorwärtsspannung der Leuchtdiode im Konstantstrombetrieb bei dieser zweiten Temperatur; und
    - (S 114) Berechnung einer linearisierten Abhängigkeit zwischen der Vorwärtsspannung der Leuchtdiode im Konstantstrombetrieb und ihrer Temperatur mittels der bei den unterschiedlichen Temperaturen gemessenen momentanen Vorwärtsspannungen.
  3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass der Schritt (S11) der Erfassung einer Abhängigkeit zwischen der Vorwärtsspannung der Leuchtdiode im Konstantstrombetrieb und ihrer Temperatur folgende Schritte aufweist:
    - (S 112) Sequentielle Erwärmung der Leuchtdiode auf mehrere unterschiedliche Temperaturen (S113) und Messung der momentanen Vorwärtsspannung der Leuchtdiode im Konstantstrombetrieb bei diesen unterschiedlichen Temperaturen; und
    - (S 115) Erzeugung einer Tabelle der Abhängigkeiten zwischen Vorwärtsspannung der Leuchtdiode im Konstantstrombetrieb und ihrer Temperatur anhand der bei den unterschiedlichen Temperaturen gemessenen momentanen Vorwärtsspannungen.
  4. Verfahren nach Anspruch 1,
    dadurch gekennzeichnet, dass
    der Schritt (S11) der Erfassung einer Abhängigkeit zwischen der Vorwärtsspannung der Leuchtdiode im Konstantstrombetrieb und der Temperatur der Leuchtdioden folgende Schritte aufweist:
    - (S112') Erwärmung der Leuchtdiode auf eine bekannte Temperatur;
    - (S113') Messung der momentanen Vorwärtsspannung der Leuchtdiode im Konstantstrombetrieb bei dieser bekannten Temperatur;
    - (S 114') Identifizierung eines Typs der Leuchtdiode; und
    - (S115') Berechnung einer linearisierten Abhängigkeit zwischen der Vorwärtsspannung der Leuchtdiode im Konstantstrombetrieb und ihrer Temperatur mittels der bei der bekannten Temperatur gemessenen momentanen Vorwärtsspannung und einer vorgegebenen Temperaturkurvenneigung für den identifizierten Leuchtdiodentyp.
  5. Verfahren nach einem der Ansprüche 2, 3 oder 4, dadurch gekennzeichnet, dass in Schritt (S11) der Erfassung einer Abhängigkeit zwischen der Vorwärtsspannung der Leuchtdiode im Konstantstrombetrieb und ihrer Temperatur der Schritt (S 113; 113') der Messung der momentanen Vorwärtsspannung der Leuchtdiode im Konstantstrombetrieb durch Anlegen eines elektrischen Stroms (S111; S111') an die Leuchtdiode erfolgt, welcher mindestens 10%, vorzugsweise mindestens 20%, besser noch mindestens 40% und am besten mindestens 60% schwächer ist als der Nennstrom der Leuchtdiode.
  6. Verfahren nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass es weiterhin den Schritt (S 116, S 116') der Speicherung der berechneten linearisierten Abhängigkeit und/oder der erzeugten Abhängigkeitstabelle als eine gespeicherte Abhängigkeit aufweist, wobei die gespeicherte Abhängigkeit außerdem als erfasste Abhängigkeit zur Berechnung der momentanen Temperatur der Leuchtdiode verwendet wird (S 117; S 117').
  7. Verfahren nach Anspruch 1,
    dadurch gekennzeichnet, dass
    der Schritt (S21) der Erfassung einer Lichtabhängigkeit zwischen der Vorwärtsspannung der Leuchtdiode im Leerlauf und dem Umgebungslicht, dem die Leuchtdiode ausgesetzt ist, folgende Schritte aufweist:
    - (212) sequentielle Beleuchtung der Leuchtdiode mit unterschiedlichen Umgebungslichtstärken und Messung (S213) der momentanen Vorwärtsspannung der Leuchtdiode im Leerlauf bei diesen unterschiedlichen Umgebungslichtstärken; und
    - (S214) Berechnung einer linearisierten Lichtabhängigkeit und/oder Erzeugung einer Tabelle der Lichtabhängigkeit zwischen Vorwärtsspannung der Leuchtdiode im Leerlauf und den Umgebungslichtstärken, denen die Leuchtdiode ausgesetzt ist, anhand der bei diesen unterschiedlichen Umgebungslichtstärken gemessenen momentanen Vorwärtsspannungen.
  8. Verfahren nach Anspruch 7,
    dadurch gekennzeichnet, dass
    es weiterhin den Schritt (S215) der Speicherung der berechneten linearisierten Lichtabhängigkeit und/oder der erzeugten Abhängigkeitstabelle als eine gespeicherte Lichtabhängigkeit aufweist, wobei die gespeicherte Lichtabhängigkeit außerdem als erfasste Lichtabhängigkeit zur Berechnung der Umgebungslichtmenge verwendet wird (S216), welche momentan auf die Leuchtdiode trifft.
  9. Computerprogrammprodukt, das direkt in den internen Speicher eines digitalen Computers geladen werden kann und Softwarekomponenten zur Ausführung der Schritte eines der Ansprüche 1 bis 9 enthält, sobald es auf einem Computer abläuft.
  10. Elektrische Schaltung (1) zur Überwachung einer Temperatur einer Leuchtdiode (2) in einem Konstantstrombetrieb, welche aufweist:
    - eine Treiberschaltung (3) zum Anlegen eines vorgegebenen Konstantstroms an die Leuchtdiode (2), um sie im Konstantstrombetrieb zu betreiben;
    - einen Speicher (4) zur Speicherung einer Abhängigkeit zwischen einer Vorwärtsspannung der Leuchtdiode (2) im Konstantstrombetrieb und ihrer Temperatur;
    - einen Spannungsmessfühler (5) zur Messung der momentanen Vorwärtsspannung der Leuchtdiode (2) im Konstantstrombetrieb;
    - eine Rechnerschaltung (6) zur Berechnung der momentanen Temperatur der Leuchtdiode (2) anhand der gespeicherten Abhängigkeit und der gemessenen momentanen Vorwärtsspannung; und
    welche dadurch gekennzeichnet ist, dass
    - die Treiberschaltung (3) weiterhin die Leuchtdiode (2) im Leerlauf betreiben kann;
    - der Speicher (4) weiterhin eine Lichtabhängigkeit zwischen der Vorwärtsspannung der Leuchtdiode (2) im Leerlauf und dem Umgebungslicht, dem die Leuchtdiode (2) ausgesetzt ist, speichern kann;
    - der Spannungsmessfühler (5) weiterhin die momentane Vorwärtsspannung der Leuchtdiode (2) im Leerlauf messen kann; und
    - die Rechnerschaltung (6) weiterhin die Umgebungslichtmenge, welcher die Leuchtdiode (2) momentan ausgesetzt ist, anhand der Lichtabhängigkeit und der gemessenen momentanen Vorwärtsspannung berechnen kann.
  11. Elektrische Schaltung (1) nach Anspruch 10,
    dadurch gekennzeichnet, dass sie weiterhin aufweist:
    einen Kalibrator (7), welcher
    den Spannungsmessfühler (5) so steuern kann, dass dieser sequentiell die momentane Vorwärtsspannung der Leuchtdiode (2) im Konstantstrombetrieb bei unterschiedlichen Temperaturen misst,
    eine linearisierte Abhängigkeit und/oder eine Tabelle der Abhängigkeiten zwischen Vorwärtsspannung der Leuchtdiode (2) im Konstantstrombetrieb und ihrer Temperatur anhand der bei den verschiedenen Temperaturen gemessenen momentanen Vorwärtsspannungen berechnen kann, und
    die berechnete linearisierte Abhängigkeit und/oder die erzeugte Abhängigkeitstabelle als Abhängigkeit im Speicher (4) speichern kann.
  12. Elektrische Schaltung (1) nach Anspruch 10,
    dadurch gekennzeichnet, dass sie weiterhin aufweist:
    einen Kalibrator (7), welcher
    den Spannungsmessfühler (5) so steuern kann, dass dieser die momentane Vorwärtsspannung der Leuchtdiode (2) im Konstantstrombetrieb bei einer bekannten Temperatur misst,
    einen Typ der Leuchtdiode (2) identifizieren kann,
    eine linearisierte Abhängigkeit und/oder eine Tabelle der Abhängigkeiten zwischen Vorwärtsspannung der Leuchtdiode (2) im Konstantstrombetrieb und ihrer Temperatur anhand der bei der bekannten Temperatur gemessenen momentanen Vorwärtsspannung und einer vorgegebenen Temperaturkurvenneigung für den identifizierten Typ der Leuchtdiode (2) berechnen kann, und
    die berechnete linearisierte Abhängigkeit als Abhängigkeit im Speicher (4) speichern kann.
  13. Elektrische Schaltung nach einem der Ansprüche 10, 11 oder 12,
    dadurch gekennzeichnet, dass
    der Kalibrator (7) weiterhin die Treiberschaltung (3) so steuern kann, dass dieser während seines Betriebs an die Leuchtdiode (2) im Konstantstrombetrieb einen elektrischen Strom anlegt, welcher mindestens 10%, vorzugsweise mindestens 20%, besser noch mindestens 40% und am besten mindestens 60% schwächer ist als der Nennstrom der Leuchtdiode (2).
  14. Elektrische Schaltung nach Anspruch 10,
    dadurch gekennzeichnet, dass
    der Kalibrator (7) weiterhin den Spannungsmessfühler (5) so steuern kann, dass dieser sequentiell die momentanen Vorwärtsspannungen der Leuchtdiode (2) im Leerlauf bei unterschiedlichen Umgebungslichtstärken misst, denen die Leuchtdiode (2) ausgesetzt ist
    eine linearisierte Lichtabhängigkeit zwischen Vorwärtsspannung der Leuchtdiode (2) im Leerlauf und der Umgebungslichtstärke, der die Leuchtdiode (2) ausgesetzt ist, anhand der bei den unterschiedlichen Umgebungslichtstärken gemessenen momentanen Vorwärtsspannung berechnen und/oder eine entsprechende Lichtabhängigkeitstabelle erzeugen kann; und
    die berechnete linearisierte Lichtabhängigkeit und/oder die Lichtabhängigkeitstabelle als Lichtabhängigkeit im Speicher (4) speichern kann.
  15. Elektrische Schaltung (1) nach einem der Ansprüche 10 bis 14, dadurch gekennzeichnet, dass er in einem tragbaren Funkkommunikationsgerät enthalten ist.
EP05005054A 2005-03-08 2005-03-08 Schaltung und Verfahren zum Überwachen der Temperatur einer Leuchtdiode Not-in-force EP1701589B1 (de)

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EP05005054A EP1701589B1 (de) 2005-03-08 2005-03-08 Schaltung und Verfahren zum Überwachen der Temperatur einer Leuchtdiode
DE602005009317T DE602005009317D1 (de) 2005-03-08 2005-03-08 Schaltung und Verfahren zum Überwachen der Temperatur einer Leuchtdiode
AT05005054T ATE406783T1 (de) 2005-03-08 2005-03-08 Schaltung und verfahren zum überwachen der temperatur einer leuchtdiode
PCT/EP2006/001102 WO2006094590A1 (en) 2005-03-08 2006-02-08 Electric circuit and method for monitoring a temperature of a light emitting diode

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010525567A (ja) * 2007-04-20 2010-07-22 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ 検知用のｌｅｄを伴う照明デバイス
US8358085B2 (en) 2009-01-13 2013-01-22 Terralux, Inc. Method and device for remote sensing and control of LED lights
US9342058B2 (en) 2010-09-16 2016-05-17 Terralux, Inc. Communication with lighting units over a power bus

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102006033233A1 (de) * 2006-07-18 2008-01-24 Austriamicrosystems Ag Verfahren und Schaltungsanordnung zum Betrieb einer Leuchtdiode
US7822086B2 (en) 2007-07-27 2010-10-26 Microvision, Inc. Laser projection temperature compensation
US9326346B2 (en) 2009-01-13 2016-04-26 Terralux, Inc. Method and device for remote sensing and control of LED lights
EP2501393B1 (de) 2009-11-17 2016-07-27 Terralux, Inc. Erkennung und steuerung einer led-stromzufuhr
US9596738B2 (en) 2010-09-16 2017-03-14 Terralux, Inc. Communication with lighting units over a power bus
WO2013090904A1 (en) 2011-12-16 2013-06-20 Terralux, Inc. System and methods of applying bleed circuits in led lamps
US8664865B2 (en) 2012-03-27 2014-03-04 General Electric Company Lighting system having an OLED light sensor
US9265119B2 (en) 2013-06-17 2016-02-16 Terralux, Inc. Systems and methods for providing thermal fold-back to LED lights
CN105844826B (zh) * 2016-04-25 2017-11-21 成都益英光电科技有限公司 利用二极管发光体的测物系统及其检测方法
CN105701938B (zh) * 2016-04-25 2018-01-02 成都益英光电科技有限公司 多二极管发光体的测物测向系统及其检测方法
CN105701940B (zh) * 2016-04-25 2017-11-21 成都益英光电科技有限公司 能判别物体运动方向的测物系统及其判别方法
EP3655818B1 (de) * 2017-07-21 2021-12-15 Lumileds LLC Methode zur kontrolle eines segmentierten blitzlicht systems
JP7440287B2 (ja) * 2020-02-05 2024-02-28 アズビル株式会社 測定装置

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL8200517A (nl) * 1982-02-11 1983-09-01 Tno Instelschakeling voor licht-emitterende diode met temperatuurcompensatie.
JPH01257383A (ja) * 1988-03-01 1989-10-13 Matsushita Electric Ind Co Ltd 半導体レーザ駆動回路
GB2224374A (en) * 1988-08-24 1990-05-02 Plessey Co Plc Temperature control of light-emitting devices
JPH0689453A (ja) * 1992-09-09 1994-03-29 Sony Corp 光ディスク記録装置
GB2288907A (en) * 1994-04-27 1995-11-01 Thomson Consumer Electronics Combined light emitting diode and photodiode
JPH08128953A (ja) * 1994-10-28 1996-05-21 Shimadzu Corp オイル劣化度検出装置
US20040052076A1 (en) * 1997-08-26 2004-03-18 Mueller George G. Controlled lighting methods and apparatus
WO1999040559A2 (en) * 1998-02-06 1999-08-12 Koninklijke Philips Electronics N.V. Organic electroluminescent device
DE19912463A1 (de) * 1999-03-19 2000-09-28 Sensor Line Ges Fuer Optoelekt Verfahren zur Stabilisierung der optischen Ausgangsleistung von Leuchtdioden und Laserdioden
DE19917239A1 (de) * 1999-04-16 2000-10-26 Hella Kg Hueck & Co Verfahren zur Ermittlung von Korrekturfaktoren zur Kompensation der Temperaturdrift der Strahlstärke einer LED
US6724158B1 (en) * 2002-10-28 2004-04-20 Honeywell International Inc. Power linearization technique for controlling the luminance of light emitting display devices

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010525567A (ja) * 2007-04-20 2010-07-22 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ 検知用のｌｅｄを伴う照明デバイス
US8358085B2 (en) 2009-01-13 2013-01-22 Terralux, Inc. Method and device for remote sensing and control of LED lights
US8686666B2 (en) 2009-01-13 2014-04-01 Terralux, Inc. Method and device for remote sensing and control of LED lights
US9161415B2 (en) 2009-01-13 2015-10-13 Terralux, Inc. Method and device for remote sensing and control of LED lights
US9342058B2 (en) 2010-09-16 2016-05-17 Terralux, Inc. Communication with lighting units over a power bus

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