EP2690344B1 - Portable electric lamp with a device for controlling a supply current and method for controlling a supply current of such a lamp - Google Patents

Description

Technical field of the invention

The invention relates to a portable electric lamp with a device for controlling a supply current and to a method for controlling a supply current of such a lamp, in particular a front electric lamp with compact housing.

State of the art

Currently, small space-saving portable electric lamps are used comprising a lighting module housed in a housing having a compact body. Generally, the lamp comprises a support provided with a strap for carrying the lamp on the head.

Such lamps can be provided with LEDs providing a powerful illumination, especially for lighting during daytime activities, and which are highly energy-consuming. But these lamps do not guarantee autonomy of operation to a user, regardless of its activity. Operating time means a time during which the lamp can operate without new energy input or without external intervention.

US patent applications US2011 / 0227500 and US2010 / 0219775 disclose a portable electric lamp comprising a control circuit for providing multiple modes of illumination.

The French patent application FR2930706 discloses a portable electric lamp comprising a lighting module provided with a light emitting diode, and a servo circuit for controlling the power of the diode to a manual setpoint.

But these documents do not describe a lamp provided with means to ensure autonomy of operation during use.

Object of the invention

The object of the invention is to overcome these drawbacks, and in particular to provide a means for controlling the current supplied to a lighting module of a sufficiently compact portable electric lamp, in order to guarantee the user autonomy of operation and an optimized lighting level.

According to one aspect of the invention, there is provided a portable electric lamp comprising a lighting module, a compact housing enclosing an electrical energy storage unit configured to supply a power supply to the lighting module.

The lamp comprises means for measuring a current consumed by the lighting module, determination means configured to develop a lighting current setpoint, calculation means for calculating an average current threshold equal to the ratio between a initial capacity of the storage unit and a duration of lamp autonomy, to calculate a maximum allowed current from a difference between the consumed current and the average current threshold and to calculate a maximum current threshold allowed to from the minimum value between the lighting current setpoint and the maximum authorized current, and limiting means configured to limit the supply current to a value less than or equal to the maximum allowed current threshold.

Thus, it is possible to determine a maximum current threshold that must not be exceeded in order to be able to supply an optimized supply current when the lamp is used. In particular, the difference between the current consumed and the average current threshold makes it possible to take into account the current consumption differences which reflect the way in which the lighting module has consumed the available current, that is to say economical way or not. Thus, it is possible to optimize the current supplied to the lighting module during a period of determined autonomy in order to guarantee a minimum lighting power during this period.

According to a general aspect of the invention, there is provided a portable electric lamp comprising a lighting module, a compact housing enclosing an electrical energy storage unit configured to supply a power supply to the lighting module, means for measuring a current consumed by the lighting module, determination means configured to produce a lighting current setpoint, calculation means for calculating a maximum authorized current from a difference between the current consumed and a reference current and for calculating a maximum allowed current threshold from the minimum value between the lighting current setpoint and the maximum allowed current, and limiting means configured to limit the supply current to a value less than or equal to the maximum allowed current threshold.

The calculating means can calculate the reference current from an initial capacity of the storage unit and a duration of autonomy of the lamp.

The calculating means may further calculate the reference current from a remaining capacity of the storage unit and a remaining duration of use of the lamp.

The lamp may comprise an optical sensor configured to develop a signal representative of the illumination induced by the lamp, the determination means being configured to develop the lighting current setpoint from the developed signal.

External lighting in the vicinity of the lamp can also be taken into account to control the supply current in order to optimize the saving of electrical energy.

The measuring means can be configured to periodically measure the current consumed by the lighting module during a given period of time, and the calculation means are configured to periodically calculate the maximum allowed current and the maximum allowed current threshold. at each specified period of time.

In this way, the measurement of the current consumed is refined in order to obtain a better precision on the calculation of the maximum permitted current threshold.

The lamp may comprise estimation means configured to estimate the initial capacity of the storage unit from a coefficient representative of the aging of the storage unit estimated from a number of complete loads of the unit. storage or from an internal resistance of the storage unit.

It is thus possible to guarantee a lamp autonomy throughout the lifetime of the storage unit.

According to another aspect of the invention, there is provided a method of controlling a supply current supplied by an electrical energy storage unit to a lighting module of a portable electric lamp.

The method comprises a development of a maximum authorized current threshold comprising a measurement of a current consumed by the lighting module, a development of a lighting current setpoint, a calculation of a mean equal current threshold. the ratio between an initial capacity of the storage unit and a duration of lamp autonomy, a calculation of a maximum allowed current from a difference between the consumed current and the average current threshold, a calculation of the maximum current threshold allowed from the minimum value between the lighting current setpoint and the maximum allowed current, the process further comprising limiting the supply current to a value less than or equal to the maximum allowable current threshold.

According to another general aspect of the invention, there is provided a method for controlling a supply current supplied by an electrical energy storage unit to a lighting module of a portable electric lamp, the method comprising a development of a maximum authorized current threshold comprising a measurement of a current consumed by the lighting module, a development of a lighting current setpoint, a calculation of a maximum current allowed from a difference between the consumed current and a reference current, a calculation of the maximum current threshold allowed from the minimum value between the lighting current setpoint and the maximum authorized current, the method further comprising limiting the current of power supply at a value less than or equal to the maximum allowed current threshold.

The reference current can be calculated from an initial capacity of the storage unit and a duration of lamp life.

It is also possible to calculate the reference current from a remaining capacity of the storage unit and a remaining duration of use of the lamp.

The lighting current setpoint may vary depending on a lighting induced by the lamp.

The step of developing the maximum allowable current threshold can be carried out periodically over a given period of time, and the current consumed by the lighting module is measured during the determined period of time.

The method may comprise an estimate of the initial capacity of the storage unit from a representative coefficient of aging of the storage unit estimated from a number of complete loads of the storage unit or from an internal resistance of the storage unit.

Brief description of the drawings

• la figure 1, illustre schématiquement un mode de réalisation d'une lampe électrique portative selon l'invention ; et
• la figure 2, illustre schématiquement les principales étapes d'un procédé de contrôle d'un courant d'alimentation de la lampe électrique portative de la figure 1.

Other advantages and features will emerge more clearly from the following description of particular embodiments and implementation of the invention given by way of non-limiting example and represented in the accompanying drawings, in which:

• the figure 1 schematically illustrates an embodiment of a portable electric lamp according to the invention; and
• the figure 2 , schematically illustrates the main steps of a method of controlling a power supply current of the portable electric lamp of the figure 1 .

detailed description

On the figure 1 schematically shows a portable electric lamp 1 comprising a lighting module 2 and a compact housing 3 enclosing an electrical energy storage unit 4, such as a battery or a battery. The unit 4 is configured to supply a supply current In, via an electrical circuit 5, to the lighting module 2. The unit 4 is preferably a rechargeable energy storage unit configured to store electrical energy in a chemical form during charging and to restore some of this electrical energy during the discharge. The lighting module 2 preferably comprises a light-emitting diode (LED), or may also comprise several LEDs, in particular LEDs with high lighting power. The portable electric lamp 1 may be a headlamp, or a flashlight, and the compact housing 3 may be made of insulating or metallic material. According to one embodiment, the lighting module 2 is separated from the compact housing 3. According to another embodiment, the lighting module 2 is included within the compact housing 3.

avec :

• Icons : le courant d'alimentation fourni à la LED au cours du temps de cycle déterminé Tcycle, c'est-à-dire le courant consommé par la LED pendant le temps Tcycle ;
• Vcons : la tension aux bornes de la résistance Rmes ;
• Rmes : la valeur de la résistance Rmes.

In addition, the housing 3 comprises a control device 6, such as for example an electronic control unit, configured to control the supply current In supplied by the storage unit 4 to the lighting module 2. The housing 3 can further comprising a management component 7 of the storage unit 4, a measurement resistor Rmes, and the lamp 1 can comprise an input module 8. The management component 7 makes it possible to control, via a connection 9, the and the discharges of the unit 4. The management component 7 is controlled by the control device 6 via a connection 10, and transmits, via a connection 11, state parameters of the unit 4, such parameters representative of the capacity of the storage unit 4, such as a remaining capacity of the storage unit CapaRest, a capacity to start the storage unit CapaDem, a consumed capacity of the storage unit CapaCons. The capacity of the storage unit is here understood to mean the quantity of electricity that can be returned by the storage unit during a discharge. The measurement resistor Rmes makes it possible to measure a current consumed Icons corresponding to the supply current In supplied to the lighting module 2 during a determined cycle time Tcycle. The resistor Rmes is connected in series between the electrical energy storage unit 4 and the LED. The control device 6 comprises measuring means 12 coupled across the resistor Rmes. The means of measure 12 measure a voltage Vcons across the resistor Rmes in order to measure the current consumed Icons from the relation: $$\mathrm{LCONS}=\mathrm{Vcons}/\mathrm{rmes}$$

with:

• Icons: the supply current supplied to the LED during the determined cycle time Tcycle, that is to say the current consumed by the LED during the Tcycle time;
• Vcons: the voltage across the resistor Rmes;
• Rmes: the value of the resistance Rmes.

Moreover, the measuring means 12 are also coupled across the terminals of the unit 4, in order to be able to measure an internal resistance Rint of the unit 4. For example, the internal resistance Rint can be measured by measuring a first voltage Vbat1 at terminals of the unit 4 and a first current consumed Icons1 by the LED. Then, a second voltage Vbat2 is measured at the terminals of the unit 4 and a second current consumed Icons2 by the LED. Thus, the value of the internal resistance Rint can be measured from the relation: $$\mathrm{Rint}=\left(\mathrm{Vbat}1-\mathrm{Vbat}2\right)/\left(\mathrm{LCONS}1-\mathrm{LCONS}2\right)\mathrm{.}$$

$$\mathrm{CapaCons}=\left(\mathrm{Vbat\_f}/\mathrm{Rint}\right)*\mathrm{Tcycle}$$

avec

• CapaDem : la capacité au démarrage de l'unité de stockage, c'est-à-dire la capacité au début de l'utilisation de la lampe 1 ;
• CapaCons : la capacité consommée de l'unité de stockage, c'est-à-dire la capacité consommée au cours du temps de cycle déterminé Tcycle ;
• Vbat_charge : la tension de charge de l'unité 4 ;
• Vbat_f : la tension fournie par l'unité 4 à la LED au cours du temps Tcycle ;
• Tcharge : le temps de charge de l'unité 4.

Thanks to the measurement of the internal resistance Rint, another mode of calculating the state parameters of the unit 4 can be offered. Indeed, the measuring means 12 can thus determine: $$\mathrm{CapaDem}=\left(\mathrm{Vbat\_charge}/\mathrm{Rint}\right)*\mathrm{Tcharge}$$

$$\mathrm{CapaCons}=\left(\mathrm{Vbat\_f}/\mathrm{Rint}\right)*\mathrm{Tsampling}$$

with

• CapaDem: the capacity at startup of the storage unit, that is to say the capacity at the beginning of the use of the lamp 1;
• CapaCons: the capacity consumed by the storage unit, ie the capacity consumed during the determined cycle time Tcycle;
• Vbat_charge: the charging voltage of unit 4;
• Vbat_f: the voltage supplied by the unit 4 to the LED over time Tcycle;
• Charge: the charging time of unit 4.

It may be noted that the charge of the storage unit 4 may be complete or incomplete, and that the determined cycle time Tcycle corresponds to a discharge time of the unit in which the unit 4 supplies the current Icons to the LED.

In addition, the input module 8 is configured to transmit to the control device 6 input parameters entered by the user. The input parameters can be, a maximum Threshold Max threshold, a minimum Threshold Threshold, and a desired duration of Autolight of the lamp 1. The maximum and minimum thresholds of illumination enable user to select a lighting power interval he wishes to use for his activity. The autonomy period Dauto corresponds to the duration for which the user wishes to practice his activity. From the parameters entered by the user, the control device 6 checks the value of the supply current In supplied to the LED so as to guarantee the user a minimum illumination during the autonomy period Dauto. In addition, the control device 6 provides optimized lighting for maximum illumination during the autonomy period Dauto. The input module 8 may be included within the housing 3, or within the lighting module 2, or may be deported within an external computer.

Moreover, the lighting module 2 comprises a module 14 for developing a lighting setpoint. The processing module 14 comprises a lighting button 15 for providing a lighting control Cmde, via a connection 16, to the control device 6. The lighting control Cmde is a function of a power lighting selected by the user via the light button 15. The lighting power can match a lighting power, low, strong, minimum, or maximum. The illumination button 15 also allows the lamp 1 to be put into service or stopped. Preferably, the processor module 14 further comprises an optical sensor 17 which supplies the control device 6 via a connection 18, a signal S representative of a lighting induced by the lamp 1. In particular, the signal S is representative of the light reflected by an illuminated object, in particular by the LED, and by other external light sources. the lamp 1. The optical sensor 17 reinforces the automation of the control of the supply current In because it makes it possible to automatically select the lighting power necessary to illuminate an object sufficiently.

The control device 6 comprises, meanwhile, a nonvolatile memory 20, an electronic clock 21, determination means 22, the measuring means 12 previously described, calculation means 23 and means 24 for limiting the current. In power supply to the LED.

The non-volatile memory 20 is coupled to the input module 8 by a connection 25 in order to save the parameters entered by the user. In addition, the memory 20 is coupled to the calculation means 23 via a connection 26 to save other calculated parameters and to transmit the saved parameters to the calculation means 23. The non-volatile memory 20 makes it possible to preserve the values of the parameters saved even after a stop of the lamp 1.

The measuring means 12 transmit the measured parameters Icons, CapaDem, CapaCons, to the calculation means 23 by a connection 27. The electronic clock 21 is configured to supply the current time Tcurrent, which it transmits via a connection 28, to the means of calculation 23. The determination means 22 elaborate a lighting current setpoint Id starting from either the received signal S or the command Cd received, and transmit the lighting current setpoint Id to the computing means 23 via a connection 30. Preferably, the lighting current set point Id is produced from the signal S, and it is inversely proportional to the quantity of light received by the optical sensor 17. In other words, the greater the quantity of light received by the optical sensor 17 is high and the lighting current set point Id is low. Thus, the lighting power of the LED is reduced when an object is strongly illuminated and vice versa. According to yet another variant, the determination means 22 develop a lighting current setpoint Id having a constant value equal to that of an average current threshold Imoyen.

Moreover, the calculation means 23 are configured to develop a maximum allowed current threshold Threshold MaxAuto, which they transmit via a connection 29 to the limiting means 24. The maximum authorized current threshold Threshold MaxAuto corresponds to a maximum power supply current. do not overtake to ensure the operation of the lamp 1 during the desired period of autonomy Dauto. In addition, the limiting means 24 are coupled by a connection 31 to the LED in order to limit the supply current In by directly controlling the LED. In a variant, the limiting means 24 control the management component 7 of the unit 4 to control the discharges so as to limit the supply current In to a value less than or equal to the Threshold MaxAuto.

In general, the measuring means 12 periodically measure the current consumed Icons by the LED during the determined cycle time Tcycle. From the current consumed Icons measured, the calculation means 23 elaborate an intermediate parameter NEDisp, also denoted level of available electrical energy, which is representative of the way in which the lamp 1 has consumed current, that is to say economically or no. In particular, the available energy level NEDisp is developed from the difference between the current consumed Icons and the average current threshold Imoyen. In addition, the value of the parameter NEDisp is saved periodically at each cycle time Tcycle, and each new value of the parameter is calculated from the previous value saved. Thus, past events, in addition to the power consumption mode, are taken into account in order to determine the value of the maximum allowed current threshold Threshold MaxAuto not to be exceeded. The current consumption of the LED may correspond to an overconsumption, in the case where it is considered that the current which has been consumed since the beginning of use of the lamp 1 is too important, that is to say that the current consumption has exceeded a certain threshold. Conversely, it may correspond to under-consumption in the case where it is considered that the current that has been consumed is below the determined threshold. The determined threshold corresponds to the average current threshold Imoyen that can provide the storage unit during the autonomy period Dauto. The calculation means 23 determine, at each new cycle time Tcycle, the new value of the intermediate parameter NEDisp from its old value, saved at the previous cycle time, and from the difference between the current consumed Icons over the time of the previous cycle and the average current threshold Imoyen. The value of the NEDisp intermediate parameter is positive or zero when over-current is consumed, or negative when under-consumed. Then, the calculation means 23 develop a maximum allowed current ImaxAuto from the intermediate parameter NEDisp. The ImaxAuto current corresponds to a current that must not be exceeded in order to guarantee the operating autonomy of the lamp 1. Furthermore, the lighting of the lamp 1 is optimized by taking into account the lighting current set point. Id. More particularly, when the intermediate parameter NEDisp is positive or zero, in the case of overconsumption, the control device 6 limits the supply current In to the minimum value between the lighting current setpoint Id and the maximum current allowed ImaxAuto. If the intermediate parameter NEDisp is negative, in the case of under-consumption, the control device 6 limits the supply current to the value of the current setpoint Id. Thus, it provides optimized lighting that does not exceed maximum allowed current ImaxAuto, in overconsumption, and does not exceed the id lighting current setpoint in under power consumption. In other words, the maximum allowed current threshold Threshold MaxAuto is equal to the minimum value between the lighting current set point Id and the maximum authorized current ImaxAuto when the available electrical energy level NEDisp is positive or zero, and the maximum current threshold allowed Threshold MaxAuto is equal to the lighting current set point Id when the available electrical energy level NEDisp is negative.

Initially, the calculation means 23 recover the value of the capacity at startup of the CapaDem storage unit, either by the measurement means 12 or by the management component 7 of the unit 4. Advantageously, it is possible to take into account account the aging of the storage unit 4 in order to refine the value of the CapaDem parameter. Aging can be estimated, for example by storing using the nonvolatile memory 20 the number of complete charges made and using a first chart of the manufacturer of the unit 4 to determine a CoefVieil aging coefficient. Then we estimate an initial capacity of the Capalnit storage unit = CapaDem * CoefVieil (equation 5). According to another estimation method, it is possible to measure the internal resistance of the Rint battery, as described above in equation 2, and to determine the CoefVieil aging coefficient from Rint and a second chart of the manufacturer of 4. The Capalnit initial capacitance corresponds to the quantity of electrical energy that can be restored by the storage unit 4 when the lamp 1 is put into service.

Then, the user enters the parameters Threshold Max, Threshold Min and Dauto from the input module 8. These parameters are then processed by the means of calculation 23 to determine their validity. For example, the maximum light threshold SeuiMax entered can not exceed a limit given by the manufacturer of the LED. The minimum ThresholdMin threshold can not be less than a minimum supply current to allow the user to read a document at a reading distance of approximately 25 cm in the dark. In addition, if the autonomy duration Dauto is greater than a determined threshold DautoMax, we limit its value to the determined threshold DautoMax = Capalnit / ThresholdMin (equation 6). As a variant, the maximum thresholds Threshold Max and minimum Threshold Min may be previously set to constant values, and not entered by the user. It is the same for the duration of autonomy Dauto. In particular, the minimum Threshold Threshold is the minimum supply current that can be provided by the storage unit 4 during the autonomy period Dauto.

• Tinit = DateDébut, avec Tinit : temps initial qui marque le début d'utilisation de la lampe 1, et DateDébut : la date de mise en service de la lampe 1 ;
• Dutil = 0, avec Dutil : la durée d'utilisation de la lampe 1 depuis le temps initial Tinit;
• Tcycle : le temps de cycle, par exemple compris entre 10 ns et 1 minute ;
• NEDisp = 0 ;
• CapaUtil = 0, avec CapaUtil : la capacité utilisée de l'unité de stockage depuis le temps initial Tinit ;
• ImaxAuto = SeuilMax.

The calculation means 23 then initialize certain parameters at the following determined values:

• Tinit = StartDate, with Tinit: initial time that marks the start of use of lamp 1, and StartDate: the date of commissioning of lamp 1;
• Dutil = 0, with Dutil: the duration of use of the lamp 1 since the initial time Tinit;
• Tcycle: the cycle time, for example between 10 ns and 1 minute;
• NEDisp = 0;
• CapaUtil = 0, with CapaUtil: the used capacity of the storage unit since the initial time Tinit;
• ImaxAuto = ThresholdMax.

Preferably, Tcycle ≤ Dauto / 10 so as to obtain a control of the progressive In supply current. Then the calculation means 23 recover the current consumed Icons, transmitted by the measuring means 12, and the lighting current setpoint Id transmitted by the determination means 22. The calculation means 23 then determine the duration of use Dutil. For example, Dutil can be determined by the relation Dutil = Dutil + Tcycle (equation 7), by incrementing at each cycle time Tcycle the Dutil parameter saved in the non-volatile memory 20. Dutil can also be determined by the following relation: Dutil = Tcurrent + Tinit (equation 8), recovering the value of the current time Tcurrent at each cycle time Tcycle.

• $$\mathrm{lmoyen}=\mathrm{Capalnit}/\mathrm{Dauto}$$
  
• $$\mathrm{CapaCons}=\mathrm{lcons}*\mathrm{Tcycle}$$
  
• $$\mathrm{CapaUtil}=\mathrm{CapaUtil}+\mathrm{CapaCons}$$
  
• $$\mathrm{CapaRest}=\mathrm{Capalnit}-\mathrm{CapaUtil}$$
  
• $$\mathrm{NEDisp}=\mathrm{NEDisp}+\left(\mathrm{lcons}-\mathrm{lmoyen}*\mathrm{Marge}\right)*\mathrm{Tcycle}$$
  
• $$\mathrm{Ratio}=\mathrm{NEDisp}/\mathrm{CapaRest}$$
  
• $$\mathrm{lmaxAuto}=\left(\mathrm{SeuilMax}-\mathrm{SeuilMin}\right)*\left(1-\mathrm{Ratio}\right)$$
  

avec

• Imoyen : le seuil de courant moyen ;
• Marge : une marge de sécurité, en pourcentage, par exemple égale à 90% ;
• Ratio : le rapport entre le niveau d'énergie disponible NEDisp et la capacité restante de l'unité de stockage CapaRest ; et
• NEDisp : paramètre intermédiaire sans unité qui représente le mode de consommation électrique de la LED, c'est-à-dire si la consommation est économique ou non.

Then, the calculation means 23 calculate certain parameters in order to determine the maximum allowed current ImaxAuto. Thus, the calculation means 23 perform the following calculations:

• $$\mathrm{lmoyen}=\mathrm{Capalnit}/\mathrm{Dauto}$$
  
• $$\mathrm{CapaCons}=\mathrm{LCONS}*\mathrm{Tsampling}$$
  
• $$\mathrm{CapaUtil}=\mathrm{CapaUtil}+\mathrm{CapaCons}$$
  
• $$\mathrm{CapaRest}=\mathrm{Capalnit}-\mathrm{CapaUtil}$$
  
• $$\mathrm{NEDisp}=\mathrm{NEDisp}+\left(\mathrm{LCONS}-\mathrm{lmoyen}*\mathrm{Margin}\right)*\mathrm{Tsampling}$$
  
• $$\mathrm{Ratio}=\mathrm{NEDisp}/\mathrm{CapaRest}$$
  
• $$\mathrm{lmaxAuto}=\left(\mathrm{SeuilMax}-\mathrm{SeuilMin}\right)*\left(1-\mathrm{Ratio}\right)$$
  

with

• Imoyen: the average current threshold;
• Margin: a safety margin, in percentage, for example equal to 90%;
• Ratio: the ratio between the available energy level NEDisp and the remaining capacity of the CapaRest storage unit; and
• NEDisp: intermediate parameter without unit that represents the power consumption mode of the LED, that is to say if the consumption is economic or not.

According to one embodiment, the calculation means 23 calculate these parameters at each cycle time Tcycle. Alternatively, CapaCons, CapaUtil, and CapaRest storage capacity state settings are determined by the management component 7 and transmitted directly to the calculation means 23. Advantageously, the calculation means 23 limit the value of the maximum allowed current ImaxAuto so that it is in the range [ThresholdMin; SeuiMax]. If the calculated value ImaxAuto is greater than ThresholdMax, then ImaxAuto = Threshold Max and if the calculated value ImaxAuto is less than ThresholdMin, then ImaxAuto = ThresholdMin.

In general, the average current threshold Imoyen is also noted reference current. The current Imoyen reference corresponds to an available current that can provide the storage unit 4 for the desired duration autonomy Dauto. The calculation means 23 calculate the reference current Imoyen from the initial capacity of the storage unit Capalnit and the duration of autonomy of the lamp Dauto. In particular, the reference current Imoyen is proportional to the ratio between the initial capacitance of the storage unit Capalnit and the duration of autonomy of the lamp Dauto. For example, the reference current Imoyen = Capalnit / Dauto (equation 9).

• SeuilMaxAuto = Id, si NEDisp ≥ 0 et Dutil < Dauto ; et
• SeuilMaxAuto = ImaxAuto, si NEDisp < 0 ou Dutil ≥ Dauto.

According to another embodiment, the calculation means 23 calculate the reference current Imoyen from the remaining capacity of the storage unit CapaRest and a remaining duration of use of the lamp Drest. For example, the calculation means 23 calculate the remaining duration of use of the lamp Drest = Dauto-Dutil. In particular, the Imoyen reference current is proportional to the ratio between the remaining capacitance of the CapaRest storage unit and the remaining duration of use of the Drest lamp. For example, the reference current Imoyen = CapaRest / Drest. In this other embodiment, the Imoyen reference current varies during the duration of use of the Dutil lamp. For example, the calculation means 23 calculate the reference current Imoyen at each cycle time Tcycle. Then, the calculation means 23 determine the maximum allowed current threshold Threshold MaxAuto from the previous parameters. In addition,

• Threshold MaxAuto = Id, if NEDisp ≥ 0 and Dutil <Dauto; and
• Threshold MaxAuto = ImaxAuto, if NEDisp <0 or Dutil ≥ Dauto.

When the LED consumes little power, that is to say under power, we saved the energy stored by the unit 4, and we have NEDisp <0. In this case we optimize the current supplied to the LED by limiting the supply current In to the value of the lighting current setpoint Id. On the other hand, when the LED consumes too much current, that is to say overconsumption, we do not have enough saves the stored energy, and we have NEDisp ≥ 0. In this case we optimize the current supplied to the LED by limiting the supply current In to the minimum value between the maximum allowed current ImaxAuto and the lighting current setpoint. Id. It is also possible to provide the LED with a supply current In equal to the value of the maximum allowed current threshold SeuilMAxAuto.

On the figure 2 the main steps of a method for controlling the supply current of an electric lamp are schematically represented. The method can be implemented by the control device 6 which has just been described. This method can be implemented in a microprocessor, in a software form or in the form of logic circuits.

In general, the method comprises a first initialization step S1, a second generation step S2 of the maximum allowed current threshold Threshold MaxAuto, and a third step S11 of limiting the supply current In. initialization S1, one retrieves the data entered by the user, in particular the ThresholdMax, ThresholdMin and Dauto, and one updates some parameters. The preparation step S2 is performed periodically at each cycle time Tcycle. The development step S2 comprises a measurement acquisition step S3 in which, in particular, the current consumed Icons is measured during the cycle time Tcycle, and the value of the lighting current setpoint Id is determined. The drawing step S2 further comprises a parameter calculation step S4, a maximum current limiting step S5, and a control step S6 of the value of the intermediate parameter NEDisp. During step S4 for calculating the parameters, the value of the parameters necessary for calculating the maximum permitted current ImaxAuto is determined. In particular, the following parameters are calculated: the intermediate parameter NEDisp, the parameter Ratio and the parameter ImaxAuto. Then, in step S5, the maximum allowed current ImaxAuto is limited so that its value is in the interval [ThresholdMin; SeuilMax]. In addition, the control step S6 makes it possible to determine the value of the maximum allowed current threshold Threshold MaxAuto that the supply current In must not exceed in order to guarantee autonomy of operation during the duration of use of the lamp. The control step S6 comprises a step S7 during which the value of the parameters NEDisp and Dutil is compared.

When NEDisp ≥ 0 and Dutil <Dauto, that is to say that as long as the use time Dutil is less than the autonomy time Dauto, the control of the supply current In is maintained in order to guarantee the autonomy of the lamp 1. In addition, when the intermediate parameter NEDisp is positive or zero, it is considered that there is an overconsumption, and in this case it performs a step S8 during which the value of the current command is compared Id lighting with the maximum allowed current value ImaxAuto. If the lighting current set point Id is greater than the maximum allowed current ImaxAuto calculated, a step S9 is performed in which the maximum allowed current threshold Threshold MaxAuto is assigned the value of the maximum allowed current ImaxAuto, and a step S10 is carried out in which the maximum current threshold Threshold MaxAuto is assigned the value of the lighting current set point Id otherwise.

On the other hand, when the intermediate parameter NEDisp is negative, it is considered that there is an under-consumption, and in this case the step S10 is performed in which the maximum current threshold Seuil MaxAuto is assigned the value of the current setpoint. In addition, when Dutil ≥ Dauto, ie if the Dutil operating time is greater than or equal to the Dauto standby time, the control method of the supply current 1 takes end.

During the limitation step S11, the supply current supplied to the LED is monitored so that the value of the supply current is less than or equal to the maximum allowed current Threshold MaxAuto. Preferably, a supply current is provided to the LED whose value is equal to the maximum allowed current threshold so as to optimize the lighting power as a function of the available capacity of the storage unit. We can note on the figure 2 that following the initialization step S1, it first performs the control step S6 because at the beginning of the control method, the value of the NEDisp parameter is zero. Then, in a second step, the step of limiting the supply current S11, the forming step S2 and again the limiting step S11, are carried out periodically according to the period of time Tcycle. Thanks in particular to the safeguarding of the intermediate parameter NEDisp, the method guarantees autonomy even after a lamp 1 has been stopped. In addition, the user can possibly modify the values SeuinMin, Threshold Max and Dauto during the use of the lamp.

• Capalnit = 2000 mAh (ou milliampère heure) ;
• SeuiMax = 700 mA ;
• SeuilMin = 50 mA ;
• Dauto = 4 heures ;
• Tcycle = 1 heure ;
• Marge = 0,9 ;
• Imoyen = CapaInit/Dauto = 2000/4 = 500 mA.

To illustrate the steps of the process just described, we can take the following example:

• Capalnit = 2000 mAh (or milliampere hour);
• SeuiMax = 700 mA;
• ThresholdMin = 50 mA;
• Dauto = 4 hours;
• Tcycle = 1 hour;
• Margin = 0.9;
• Imoyen = CapaInit / Dauto = 2000/4 = 500 mA.

At the start of the process, during the first hour of use, that is to say at Dutil = 0 hours, for example the lighting current setpoint Id = 200 mA. We then perform the initialization step S1, then the control step S6 where we have NEDisp = 0 and ImaxAuto = Threshold Max = 700 mA. During the control step S6, step S7 is carried out, then steps S8 and S10. Then step S11 is performed in which the supply current In is limited to the value SeuilMaxAuto = Id = 200 mA. Therefore, during the first hour of use of the lamp, the feed current In will always be less than or equal to 200 mA, preferably equal to 200 mA.

Then, during the second hour of use, that is to say Dutil = 1 hour, for example the lighting current setpoint Id = 700 mA. In addition, the lamp 1 consumed Icons current = 200 mA during the previous cycle time Tcycle = 1 hour. Next, the calculation step S4 is performed, in which: $$\begin{array}{l}\mathrm{CapaRest}=\mathrm{Capalnit}-\mathrm{CapaUtil}=\mathrm{2000}-\mathrm{200}=\mathrm{1800}\mathrm{mAh};\mathrm{and}\\ \mathrm{NEDisp}=\mathrm{NEDisp}+\left(\mathrm{LCONS}-\mathrm{lmoyen}*\mathrm{Margin}\right)*\mathrm{Tsampling}=\mathrm{0}+\left(\mathrm{200}-\mathrm{500}*\mathrm{0},\mathrm{9}\right)*\mathrm{1}=-\mathrm{250.}\end{array}$$

et $$\mathrm{lmaxAuto}=\left(\mathrm{SeuilMax}-\mathrm{SeuilMin}\right)*\left(1-\mathrm{Ratio}\right)=\left(700-50\right)*\left(1+0,1388\right)=740,22\mathrm{mA}\mathrm{.}$$

In addition, we calculate: $$\mathrm{Ratio}=\mathrm{NEDisp}/\mathrm{CapaRest}=-250/1800=-0,1388;$$

and $$\mathrm{lmaxAuto}=\left(\mathrm{SeuilMax}-\mathrm{SeuilMin}\right)*\left(1-\mathrm{Ratio}\right)=\left(700-50\right)*\left(1+0,1388\right)=740,22\mathrm{my}\mathrm{.}$$

Then the control step S6 is carried out again during which the steps S7 and S10 are carried out. Then step S11 is performed in which the supply current In is limited to the value SeuilMaxAuto = Id = 700 mA.

Then, during the third hour of use, that is to say Dutil = 2 hours, for example the lighting current setpoint Id = 700 mA. In addition, the lamp 1 consumed the current Icons = 700 mA during the previous cycle time Tcycle = 1 hour. Next, the calculation step S4 is performed, in which: $$\begin{array}{l}\mathrm{CapaRest}=\mathrm{Capalnit}-\mathrm{CapaUtil}=\mathrm{2000}-\left(\mathrm{200}+700\right)=\mathrm{1100}\mathrm{mAh};\mathrm{and}\\ \mathrm{NEDisp}=\mathrm{NEDisp}+\left(\mathrm{LCONS}-\mathrm{lmoyen}*\mathrm{Margin}\right)*\mathrm{Tsampling}=-\mathrm{250}+\left(\mathrm{700}-\mathrm{500}*\mathrm{0},\mathrm{9}\right)*\mathrm{1}=\mathrm{0.}\end{array}$$

et $$\mathrm{lmaxAuto}=\left(\mathrm{SeuilMax}-\mathrm{SeuilMin}\right)*\left(1-\mathrm{Ratio}\right)=\left(700-50\right)*\left(1-0\right)=650\mathrm{mA}\mathrm{.}$$

In addition, we calculate: $$\mathrm{Ratio}=\mathrm{NEDisp}/\mathrm{CapaRest}=0/1100=0;$$

and $$\mathrm{lmaxAuto}=\left(\mathrm{SeuilMax}-\mathrm{SeuilMin}\right)*\left(1-\mathrm{Ratio}\right)=\left(700-50\right)*\left(1-0\right)=650\mathrm{my}\mathrm{.}$$

Then steps S7, S8 and S9 are carried out, then step S11 during which the supply current In is limited to the value SeuilMaxAuto = ImaxAuto = 650 mA.

Then, during the fourth and last hour of use, that is to say Dutil = 3 hours, for example the lighting current setpoint Id = 700 mA. In addition, the lamp 1 consumed the current Icons = 650 mA during the previous cycle time Tcycle = 1 hour. Next, the calculation step S4 is performed, in which: $$\begin{array}{l}\mathrm{CapaRest}=\mathrm{Capalnit}-\mathrm{CapaUtil}=\mathrm{2000}-\left(\mathrm{200}+700+650\right)=450\mathrm{mAh};\mathrm{and}\\ \mathrm{NEDisp}=\mathrm{NEDisp}+\left(\mathrm{LCONS}-\mathrm{lmoyen}*\mathrm{Margin}\right)*\mathrm{Tsampling}=\mathrm{0}+\left(\mathrm{650}-\mathrm{500}*\mathrm{0},\mathrm{9}\right)*\mathrm{1}=\mathrm{200.}\end{array}$$

et $$\mathrm{lmaxAuto}=\left(\mathrm{SeuilMax}-\mathrm{SeuilMin}\right)*\left(1-\mathrm{Ratio}\right)=\left(700-50\right)*\left(1-0,444\right)=361,4\mathrm{mA}\mathrm{.}$$

In addition, we calculate: $$\mathrm{Ratio}=\mathrm{NEDisp}/\mathrm{CapaRest}=200/450=0,444;$$

and $$\mathrm{lmaxAuto}=\left(\mathrm{SeuilMax}-\mathrm{SeuilMin}\right)*\left(1-\mathrm{Ratio}\right)=\left(700-50\right)*\left(1-0,444\right)=361,4\mathrm{my}\mathrm{.}$$

Steps S7, S8 and S9 are then carried out, then step S11 during which the supply current In is limited to the value SeuilMaxAuto = ImaxAuto = 361.4 mA. During the last hour of use, the supply current In supplied to the LED is equal to 361.4 mA. Therefore, at the end of the control process, we will have CapaRest = CapaInit - CapaUtil = 2000 - (200 + 700 + 650 + 361.4) = 88.6 mAh. We have guaranteed a minimum current Illumination equal to the minimum threshold ThresholdMin during the lamp use time. In addition, the illumination produced by the lamp 1 has been optimized so as to provide a maximum supply current during each cycle time.

Such a lamp provided with a device for controlling the supply current is particularly suitable for automated use of the lamp. For example, when the user wishes to illuminate his journey, without external energy input and without worrying about the setting of the lighting produced by the lamp. Such a device provides illumination optimized according to what has already been consumed in current and depending on what remains to be provided during the remaining use time, while ensuring a lamp operating autonomy.

Claims (16)

1. Portable electric lamp comprising a lighting module (2), a compact housing (3) enclosing an electric power storage unit (4) configured to provide a power supply current (In) to the lighting module (2), means for measuring (12) a current consumed (Icons) by the lighting module, determination means (22) configured to generate a lighting current set point (Id), characterized in that the lamp further comprises calculation means (23) for calculating an intermediate parameter (NEDisp) representative of the available power level from a difference between the consumed current (icons) and a reference current (Imoyen) and from a previous value of the intermediate parameter, for calculating a maximum authorized current (IMaxAuto) from the intermediate parameter (NEDisp) and for calculating a maximum authorized current threshold (SeuilMaxAuto), said maximum authorized current threshold being equal to: i) the minimum value between the lighting current set point (Id) and the maximum authorized current (IMaxAuto) when the intermediate parameter (NEDisp) is positive or zero, or ii) the lighting current set point (Id) when the intermediate parameter (NEDisp) is negative, and limiting means (24) configured to limit the power supply current (In) to a value lower than or equal to the maximum authorized current threshold (SeuiMaxAuto).
2. Lamp according to claim 1, wherein the calculation means (23) calculate the reference current from an initial capacity of the storage unit (4) and a lamp autonomy time.
3. Lamp according to claim 1, wherein the calculation means (23) calculate the reference current from a remaining capacity of the storage unit (4) and a remaining lamp service time.
4. Lamp according to claim 2 or 3, wherein the calculation means (23) limit the value of the maximum authorized current to a value between a minimum illumination threshold and a maximum illumination threshold.
5. Lamp according to claim 4, comprising an input module (8) configured to modify values of the lamp autonomy time, the minimum illumination threshold and the maximum illumination threshold.
6. Lamp according to one of claims 1 to 5, comprising an optical sensor (17) configured to generate a signal representative of the lighting induced by the lamp, the determination means (22) being configured to generate the lighting current set point from the generated signal.
7. Lamp according to one of claims 1 to 6, wherein the measurement means (12) are configured to periodically measure the current consumed by the lighting module (2) during a determined time period, and the calculation means (23) are configured to periodically calculate the maximum authorized current and the maximum authorized current threshold at each determined time period.
8. Lamp according to one of claims 1 to 7, comprising estimation means configured to estimate the initial capacity of the storage unit from a coefficient representative of the aging of the storage unit (4) estimated from a number of full charges of the storage unit (4) or from an internal resistance (Rint) of the storage unit (4).
9. Method for controlling a power supply current (In) provided by an electric power storage unit (4) to a lighting module (2) of a portable electric lamp, characterized in that it comprises a generation (S2) of a maximum authorized current threshold comprising measuring (S3) a current consumed (Icons) by the lighting module, generating a lighting current set point (Id), calculating (S4): i) an intermediate parameter (NEDisp) representative of the available power level from a difference between the consumed current (Icons) and a reference current (Imoyen) and from a previous value of the intermediate parameter, ii) a maximum authorized current (IMaxAuto) from the intermediate parameter (NEDisp) and iii) a maximum authorized current threshold (SeuilMaxAuto), from the minimum value between the lighting current set point and the maximum authorized current, said maximum authorized current threshold (SeuilMaxAuto) being equal to: iii.1) the minimum value between the lighting current set point (Id) and the maximum authorized current (IMaxAuto) when the intermediate parameter (NEDisp) is positive or zero, or iii.2) the lighting current set point (Id) when the intermediate parameter (NEDisp) is negative, the method further comprising a limitation (S11) of the power supply current (In) to a value lower than or equal to the maximum authorized current threshold (SeuilMaxAuto).
10. Method according to claim 9, wherein the reference current is calculated from an initial capacity of the storage unit and a lamp autonomy time.
11. Method according to claim 9, wherein the reference current is calculated from a remaining capacity of the storage unit and a remaining lamp service time.
12. Method according to claim 10 or 11, wherein the value of the maximum authorized current is limited to a value between a minimum illumination threshold and a maximum illumination threshold.
13. Method according to claim 12, wherein the values of the lamp autonomy time, the minimum illumination threshold and the maximum illumination threshold are modified during lamp service time.
14. Method according to one of claims 9 to 13, wherein the lighting current set point varies according to a lighting induced by the lamp.
15. Method according to one of claims 9 to 14, wherein the step of generation (S2) of the maximum authorized current threshold is periodically carried out during a determined time period, and the current consumed by the lighting module is measured (S3) during the determined time period.
16. Method according to one of claims 9 to 15, comprising estimating the initial capacity of the storage unit from a coefficient representative of the aging of the storage unit (4) estimated from a number of full charges of the storage unit (4) or from an internal resistance (Rint) of the storage unit (4).

Images