WO2013088060A2

WO2013088060A2 - Bulb device for regulating individual lighting, in particular for public lighting

Info

Publication number: WO2013088060A2
Application number: PCT/FR2012/052884
Authority: WO
Inventors: Maurice Gainville; Bernard HENROTTE
Original assignee: Maurice Gainville
Priority date: 2011-12-12
Filing date: 2012-12-11
Publication date: 2013-06-20
Also published as: FR2984071B1; WO2013088060A3; FR2984071A1; FR2983941A1; FR2983941B1

Abstract

The invention relates to a bulb device comprising at least one lighting means and a socket cap, and also, in particular, at least one printed circuit inside said bulb device and housed in the socket cap, for regulating an electrical power supply of said lighting means. The device also contains at least one sensor, and the printed circuit then comprises at least one microcontroller that receives signals from the sensor and establishes regulating setpoints for the electrical power supply of said lighting means depending on these signals. Such means give the bulb device an embedded intelligence, and, as a result, complete functioning autonomy.

Description

Light bulb device with autonomous lighting regulation, especially for public lighting

The invention relates to a light bulb device connected to means for managing and controlling the power supply of a lighting means of the device.

As part of the field of public lighting, there are management solutions for lighting devices including "streetlight" type. Conventionally, the known solutions have at least one control point for regulating the supply of streetlight bulbs so as to turn them on or off.

It can thus be expected to control the supply of a set of street lamps from the same point, called "centralized". These streetlights are usually connected to the centralized control point via an electrical network. Conventionally, the centralized control point comprises at least one power control unit connected to at least one light sensor (internal or external to the control point), which unit is able to:

detect an outside brightness level detected by the light sensor, and decide on the switching on or off of the street lights to which the control point is connected according to the level of brightness detected.

In this way, the control point controls the lighting of the street lamps, in case of detection of a low external luminosity (typically at night, after or at dusk) and their extinction, in case of detection of a strong external luminosity ( typically by day, after or at dawn).

However, in the event of a malfunction of the light sensor and / or the power control unit, the centralized control point is no longer able to regulate the power supply of the street lamps normally, which may for example, by blocking streetlights in an operating state that is off or on (regardless of the level of brightness captured).

Another solution is that the control point of a lamppost is assigned directly to this lamppost. In this solution, the checkpoint only regulates the power supply of the lamppost to which he is assigned. For example, the control point is in the form of an electrical box attached to the lamppost. This box may typically include a power control unit connected to a brightness sensor. The electrical box is interfaced between the light source of the street lamp and the power supply that this lamp post receives. Thus, a malfunction of the control point affects only the lamp to which it is assigned and presents an advantageous alternative to the problem mentioned above relating to the centralized control point.

However, an infrastructure according to which each lamppost has a control point is heavy and complex to set up (electrical box installations). In addition, its implementation can be expensive (additional component costs and labor for computer programming and installation).

In parallel, it may be advantageous to control the operating conditions of the bulb of the lamppost. Indeed, if the operating conditions of the bulb are optimized, the bulb can consume less energy while preserving its longevity. To do this, the control points may include additional means (a temperature sensor for example) for monitoring the operating conditions of the bulbs and thus adapt their power supply so as to operate in optimal conditions.

Nevertheless, the addition of these additional resources most often requires an adaptation of the pre-existing infrastructure of the street lamps and a reprogramming of the control points. Here again, the implementation of such a solution can be complex, expensive or prohibitive.

The present invention improves the situation.

The invention proposes an approach according to which each bulb device is autonomous in power regulation and internally comprises means for implementing functionalities of the aforementioned type, like the control points of the state of power. the technique.

For this purpose, the present invention provides a light bulb device comprising at least one lighting means and a base, and in particular at least one internal printed circuit board. bulb device and housed in the base, for regulating a power supply of said lighting means.

Thus, the bulb device is particularly suitable in particular for use in the context of a street lamp and thus solves the problems posed by the state of the art because:

the control functions are embedded in the bulb device (no influence on the operation of other streetlights in the event of malfunction), no additional infrastructure required (control point counterpart functions embedded in the light bulb device a simple replacement of an old lamppost bulb by the bulb device according to the invention makes it possible to obtain the power regulation functions), and

functioning according to the optimal conditions of use for the light source of the lamppost (autonomous regulation of the supply in accordance with the recommended conditions of use).

In addition, according to the tests carried out, it has been observed that the aforementioned printed circuit was able to withstand high temperatures, of the order of 40 to 60 ° C, (due to the ignition of the bulb device during several hours) if, in particular, he was lodged in the pellet. Moreover, in an exemplary embodiment presented below, it can advantageously be provided one or more orientation sleeves of the lighting means, between the lighting means and the base, which further contributes to thermal insulation of the circuit printed.

Advantageously, the device also carries at least one sensor, and the printed circuit then comprises at least one microcontroller recovering signals from the sensor and setting regulation instructions for the power supply of said lighting means as a function of these signals. Such means give the bulb device an embedded intelligence, and, in fact, a total operating autonomy. More particularly, in one embodiment, the printed circuit comprises at least one electrical connection means for receiving a power supply from the base and regulating said power supply for said lighting means. The aforementioned sensor may for example be a temperature sensor of the lighting means for transmitting to the printed circuit temperature information specific to the lighting means. It is thus possible to limit the power supply of the lighting means if it is measured for example a temperature above a threshold.

In addition or alternatively, the bulb device may comprise a brightness sensor for transmitting to the printed circuit information relating to natural light surrounding the bulb device. It is thus possible to detect, for example, twilight conditions for initiating the lighting of the lighting means or the sunrise conditions for controlling an extinction of the lighting means.

Advantageously, the aforementioned luminosity sensor can also be housed in the base, the latter being made of a translucent material at a wavelength range greater than 750 nm to capture the aforementioned natural light. In addition or alternatively, the base may include an opening for capturing said natural light.

In fact, natural light, at dusk and dawn, has a low color temperature (with a strong spectral component in the infrared, especially the near infrared or beyond 750 nm). It is desired that the brightness sensor is sensitive especially at dusk and dawn to respectively turn on and off the lighting means. Furthermore, it is desired that the sensor is not disturbed by parasitic lights, especially by the lighting means itself. Thus, the choice of this spectral filtering of the light captured, made by the base, makes it possible to limit the influence of the lighting means in the light captured and to furthermore favor the detection of natural light, especially at dusk and at night. 'dawn.

The above translucent material, in which the pellet is made, can be for example dyed red to filter wavelengths less than 750 nm. Similarly, it may be advantageous to choose a lighting means comprising a light source emitting in a spectrum between 400 and 700 nm, with a relatively high emission around 500 nm. On the one hand, the light emitted by the lighting means is very limited in the spectral zone of detection of the brightness sensor. On the other hand, the strong emission at 500 nm is advantageous in that it is favorable to night vision (scotopic) as detailed below with reference to Figure 3B. Thus, almost all the energy consumed by the lighting means is used for night vision (around 500 nm), which is particularly advantageous for an application to urban lighting.

In a particular embodiment, the bulb device comprises an orientation base forming an interface between the lighting means and the base. The orientation base comprises at least a first sleeve secured to the lighting means and movable in rotation for angular adjustment (in azimuth, as will be seen below) of the lighting means relative to the base, around a main axis of the base. The main axis of the base is of course the axis of rotation around which the base is rotated to be secured and connected to a socket.

In addition or alternatively, the orientation base comprises at least a second sleeve of cylindrical or frustoconical shape delimited by two non-parallel planes (Figure 9). This second sleeve allows an angular adjustment (in elevation, here) of the lighting means relative to the base, about an axis perpendicular to the main axis of the base.

Finally, the cooperation of these two sleeves allows angular connection in azimuth and elevation, as will be seen below with reference to Figure 8, which is particularly advantageous for the adjustment of an urban area (a protected passage for example) in the case in particular of a lighting means comprising a directional beam light source.

Advantageously, the printed circuit includes a program for regulating the power supply of the lighting means according to a plurality of time ranges corresponding to at least:

an extinction of the lighting means on a first range, and

- Lighting of the lighting means at a chosen level of light intensity, on a second range.

In the embodiment according to which the bulb device comprises at least one sensor, the microcontroller can then determine the level of luminous intensity chosen as a function of the signals delivered by the sensor. The printed circuit may further control a variable light intensity level as a function of time sub-ranges of the second range, as presented hereinafter, according to an advantageous method of achieving this functionality. Thus, the present invention also aims at a method for regulating the electrical power supply of a light bulb device, in which at least one printed circuit internal to the light bulb device and housed in its base is provided for regulating a power supply of the light bulb. means for illuminating the bulb device, the device further including at least one sensor, and the printed circuit is then provided with at least one microcontroller recovering signals from the sensor and setting instructions for regulating the power supply of said means lighting according to these signals.

In particular, in one embodiment, the power supply of the lighting means is regulated according to a plurality of time ranges corresponding to at least:

an extinction of the lighting means on a first range, and

It can be advantageously defined sub-ranges of the second range in which it may be desired for example a strong lighting in the early evening, lower in the middle of the night, and strong again at the end of the night. For this purpose, the aforementioned method may comprise more particularly the steps:

- find a time variable, and

comparing the time variable with at least one threshold value to identify at least one transition between two sub-ranges of the second time range

(as will be seen in more detail with reference to Figure 2 commented below).

In the method, an environmental brightness of the bulb device can be measured and compared to a first threshold value, so that the beginning of the second range is determined by an ambient brightness of the bulb device less than this first threshold value. In addition or alternatively, an environmental brightness of the bulb device is measured and compared to a second threshold value (possibly but not necessarily identical to the first threshold value), and the end of the second range is determined by an ambient brightness of the bulb device greater than this second threshold value.

In addition or alternatively, the temperature of the illumination means of the bulb device can also be measured and compared with a third threshold value, and in this way the chosen level of light intensity is lowered if the measured temperature is greater than this third threshold value.

The present invention also relates to a computer program comprising instructions for implementing the above method, when this program is executed by a processor. As such, it will be understood that a flowchart of the general algorithm of this computer program can be illustrated by way of example in FIG.

Other features and advantages of the invention will appear on examining the detailed description below, and the attached drawings in which:

FIG. 1 illustrates an exploded view of the bulb device according to one embodiment of the invention,

FIG. 2 illustrates the main steps of a method for autonomously regulating the illumination of the bulb device in an exemplary embodiment;

FIG. 3A illustrates an example of spectral sensitivity curve of the brightness sensor used in the bulb device,

FIG. 3B illustrates the spectral distribution of the luminous efficiency perceived by the human eye between a day vision and a night vision,

FIG. 3C illustrates the radiation power of three "LED" type light sources with different color temperatures,

FIG. 4A shows a front view of the end of the upper part of the base of the bulb device in an exemplary embodiment of the invention,

FIG. 4B illustrates a partial view of the end of the upper part of the base according to the embodiment of FIG. 4A,

FIG. 5 illustrates a sectional view of the assembled bulb device,

FIG. 6 illustrates another sectional view of the bulb device assembled at an angle of orientation different from that presented in FIG. 5; FIG. 7A illustrates a sectional view of another possible embodiment of the invention,

FIG. 7B illustrates another sectional view of the embodiment of the invention presented in FIG. 7A,

FIG. 8 illustrates an exemplary implementation of the invention in the context of a public lighting device, and

FIG. 9 illustrates in detail an exemplary embodiment of the sleeve 34 of FIG.

Referring first to Figure 1 which shows an exploded view of the bulb device 1, which comprises:

a pellet 2,

lighting means 4,

an orientable base 3 of the lighting means 4 (described in detail below with reference to FIGS. 4A, 4B, 5 and 6), and

a cover 5 of the lighting means 4.

The base 2 consists of at least a lower part 22 and an upper part 24. Here, the term "lower part 22" is understood to mean that part of the base which is housed in a homologous socket, when the bulb device is put in place. in use.

The lower portion 22 of the base 2 is preferably preformed in a longitudinal threaded form of the "male socket" type intended to cooperate with a female socket (not shown in the figures). The invention is not limited to this embodiment and applies to other types of cooperation caps / sockets such as bayonet, pin, or other type.

When the lower portion 22 of the base 2 and a female socket are paired, their combination ensures the supply of electricity and the mechanical maintenance of the bulb device 1.

The lower portion 22 of the base 2 is extended into an upper portion 24. This extension is initiated by a first element 24A of the upper portion 24 for example of conical shape. In continuity, a second element 24B of cylindrical shape extends the first element 24A conical. Finally, this second element 24B has a preformed end 24C for cooperating with the orientable base 3.

In the enclosure that has the structure of the upper portion 24, printed circuits 60 are advantageously accommodated. By way of purely illustrative example, provision may be made optionally for locations provided for this purpose and, in such locations, slides or gutters preformed at the inner surface of the enclosure (not shown in the figures) of the 24. Preferentially, the printed circuits 60 are preformed to the geometric shape constraints imposed by the arrangement of the elements 24A, 24B and 24C. Still according to the example shown in Figure 1, there is shown two printed circuits 60 of polyhedral shape which conform to the first conical element 24A and the second cylindrical element 24B.

In the example shown in FIG. 1, the bulb device 1 comprises two printed circuits 60 housed in the upper part 24. In a variant, it will be understood that the invention applies to a device with one or more than two printed circuits 60, which are advantageously housed in the upper part 24 of the base.

Indeed, in a preferred embodiment, the printed circuits are thus placed at a distance from the lighting means 4, whose Joule effect heating is likely to cause a degradation of the printed circuits 60. It is also taken the precaution, as it is will see later, to use a heat sink 402 mounted at the lighting means 4 in the bulb device 1. Furthermore, the printed circuits 60 are electrically connected to the lower portion 22 to:

- receive a power supply, and

implementing functions for which they are intended, as described below, for regulating the power supply of the lighting means 4.

According to an exemplary embodiment of the bulb device 1, the printed circuits 60 are electrically connected to the lower part 22 via connection means electrical 60a. As a purely illustrative example, the electrical connection means may for example be electrical terminals.

The printed circuit boards 60 are also electrically connected to the lighting means 4 of the bulb device 1, which interface between the electrical source of the base 2 and the lighting means 4. Thus, the printed circuits 60 provide control and control. management of the power supply of this lighting medium 4.

In this way, the printed circuit boards 60, through the control and management of the lighting they provide, confer on-board "intelligence" to the light bulb device 1, as well as, as will be seen below, an autonomy operating mode to the bulb device 1, regardless of the characteristics of the electrical source to which it is connected.

To do this, the printed circuits 60 perform at least one function called "driver" (or "driver") and "command". In the example shown in FIG. 1, each function is respectively assigned to a printed circuit 60. However, it is recalled that the invention is not limited to this embodiment and applies to a device with one or more circuits. printed matter 60 in which case the "driver" and "control" functions are grouped together on the same printed circuit or distributed on different printed circuit boards of the bulb device 1.

The "driver" function of a printed circuit board 60 is used to regulate the supply coming from the electrical source (lower part 22 paired with a female socket) to which the base 2 is connected in order to supply the printed circuit board 60 comprising the "control" function described below, as well as the lighting means 4.

The printed circuit 60 comprising the "control" function is advantageously of the "microcontroller" (or microprocessor) type in order to implement the method according to the invention for controlling and managing the supply of the lighting means 4. method comprises iteratively executing a routine according to which parameters relating to the environmental conditions of the bulb device 1 are read by sensors and compared to thresholds in order to establish instructions for adapting the power supply of the means. 4. For this purpose, the parameters identified are, by way of non-limiting examples, the temperature, brightness and / or presence (to trigger lighting in response to a presence for example).

In an example where a brightness sensor and a temperature sensor are provided:

the brightness sensor 26 (FIG. 1) can advantageously be placed in the base 2 to limit the influence of the lighting means 4 when it is in use, in the brightness reading, and

the temperature sensor 406b (FIG. 1) is preferably housed in the lighting means 4 for a finer estimation and a more immediate anticipation of overheating of the lighting means 4.

Reference is now made to FIG. 2 to describe the method of control and management of the supply of the lighting means 4 implemented by the "control" function performed by one of the printed circuits 60.

For each routine, in step VI, a brightness value LUM is read by the aforementioned brightness sensor 26, which is connected to the printed circuit 60 executing the "control" function. At the test step T2, the brightness value LUM measured is subjected to a test of exceeding a threshold L ₀ brightness. The threshold L ₀ considered is advantageously an intermediate brightness value below which the light is considered as a brightness level of a night mode (low luminance value LUM) and above which the light is considered as a brightness level of a day mode (high LUM brightness value). To do this, the test T2 checks whether the detected luminosity LUM is lower than the intermediate threshold value L ₀ .

If the test T2 is not satisfied (arrow N at the output of the test), so if the brightness LUM is greater than the threshold L ₀ , in step S3, the state of the lamp, noted here LAMP_STATE, is placed in an "off" state, noted here "OFF". At the same time, the luminous intensity, noted here LAMPJL, applied to the illumination means 4 is placed (by emission of a control regulation of the power supply) at a level N ₀ which, preferably, is zero or close to zero. . It will thus be understood that the printed circuit 60 comprising the "control" function interacts on the luminous intensity LAMP_L of the lighting means 4 by establishing regulation instructions for the electrical power supply of the lighting means. At this step S3, a time counter (or "timer") of the printed circuit 60, which, it will be remembered, is advantageously a microcontroller or a microprocessor (typically comprising for this purpose a processor clock, for example). The use of a timer is known to the state of technology for such electronic components and materialize as internal devices for measuring time periods. Nevertheless, an embodiment of such a feature in an autonomous bulb device, according to an advantageous characteristic of an embodiment of the invention, makes it possible in particular to measure lighting times and more particularly to establish time slots. lighting. The use of the internal timer on the printed circuit board 60 comprising the "command" function makes it possible to record a time variable called hereinafter "TIMER" while avoiding the disruption constraints inherent in any type of time counter and / or other time systems depending on the time. a power supply (battery, battery or mains supply). If the T2 test is satisfied (arrow O at the output of the test), the method generates a second test T4 verifying the ignition state of the bulb device 1 and more particularly if the LAMPJSTATE variable is in an ON state. If the T4 test is satisfied, the variable LAMP_STATE is set to ON and the process proceeds to the next step V6 of recovery of the temperature variable T. If the T4 test is not satisfied, the light bulb device 1 passes. from a turned off state to a state turned on in step S5. At this step, the variable LAMP_STATE of the light bulb device 1 changes from an OFF state to an ON state. In addition, the counter of the time variable TIMER is switched on by the execution of the function LAUNCHJTEMER. This implementation allows control and management of the lighting means 4, by controlling its power supply according to time slots defined by counting the TIMER time variable, as described below.

In a next step V6, a sensor reads a temperature T to control the operating temperature of the lighting means 4, as follows. An overrun test threshold temperature T ₀ is conducted at step T7. The threshold temperature T ₀ is preferably a temperature from which the lighting means 4 is in a state of overheating (temperature above a range of operating condition recommended for the lighting means 4). If the T7 test is not satisfied, the luminous intensity LAMP_L is decreased to a level Ni (step S8) preferentially lower than the maximum luminous intensity recommended. As a purely illustrative example, the brightness level Ni represents 70% of the maximum level of light intensity recommended.

If the T7 test is satisfied, the time value TIMER is retrieved in step V9 to check that it remains greater than a threshold time value ti (at test T 10). This threshold time value ti is predefined. It corresponds to a desired moment for changing the brightness of the lighting means 4 of the bulb device 1. As a purely illustrative example, the threshold time value ti is 7200 seconds, which corresponds to a first time slot ( two hours) during which it may be desired to maintain a constant lighting, as will be seen later.

If the test T10 is not satisfied, the luminous intensity LAMP_L is then placed at a level of luminous intensity N ₂ at the step SU. In this case, the device is in a lower operating time range ti and is advantageously placed at a maximum light intensity level or higher than the recommendations for use of the lighting means 4. For example, the light intensity level N ₂ may represent up to 140% of the maximum level of light intensity recommended (to obtain a raised brightness of the area illuminated by the bulb device 1, in an advantageous application described below) . If the test T10 is satisfied, a second test Tl 2 is conducted with the time value T ER to check whether it becomes greater than a second threshold time value t ₂ preferentially predefined. For purely illustrative purposes, the threshold time value t ₂ is 21600 seconds (ie six hours, which corresponds to four hours more than the first threshold ti, to thus define a second time slot of four hours after the first time slot of two o'clock).

If the test T12 is not satisfied, the luminous intensity LAMP_L is placed at a luminous intensity level N ₃ in the next step S 13. In this case, the device is in an intermediate operating time range included between t [and t ₂ . During this beach time, the level of the luminous intensity of the bulb device 1 is advantageously placed at the maximum level recommended for the use of the illumination means 4. For example, the luminous intensity level N3 represents 100% of the maximum level of luminous intensity recommended for the lighting medium 4.

If the test Tl 2 is satisfied, the bulb device 1 is in a time range greater than t ₂ and the luminous intensity LAMP_L is placed (step S 14) at a level of luminous intensity N ₄ advantageously less than the maximum recommended. For example, the level of light intensity N ₄ represents 80% of the maximum level of light intensity recommended. In such an example, it is possible to consider a time slot (greater than t _2, for example) where it is desired to save energy and to limit the energy consumption of the light bulb device 1 by placing its brightness level at a level below the maximum recommended.

For example, a high luminous intensity (level N ₂ ) is desirable during the first two hours (TIMER <t ^ ignition of the bulb device 1, then an intermediate light intensity (level N ₃ ) is preferable on the next four hours (TIMER> ti and TIMER <t ₂ ), before being finally placed at a reduced luminous intensity (level N4) beyond these time periods (TIMER> t ₂ ) Typically, this embodiment example is particularly suitable for public lighting.The light bulb device 1 of the invention is associated with a public lighting device of the "street lamp" type and makes it possible to have different light intensity lighting according to time slot. For example beyond 23 hours or midnight (time range greater than t ₂ ), the streets are less busy and it is preferable that the light intensity of public lighting is lower, for reasons of energy saving , well ndu, but also to solve problems of light nuisance. In addition, the light intensity can be set to a low security level (level N when the operating temperature T of the lighting means 4 exceeds a critical threshold value T _0. Thus, when the lighting means 4 is considered in the state of "overheating", it is brought back to a normal operating temperature (lower than T ₀ ) by a decrease of its luminous intensity (level NI) before resuming levels of higher light intensity (levels N _2, N ₃ or N _4).

However, according to the tests carried out, it is possible to exceed a recommended maximum brightness level (for example by supplying a power supply above a maximum power recommended for a given lifetime of the lighting means) to "over-light" advantageously over given time slots (for example at the beginning of the evening) and, on the other hand, to deliver a brightness level below a recommended level (for example by supplying a power supply below the maximum power recommended on given time slots (eg in the middle of the night).

Finally, all of the steps S3, S8, S11, S13 and S14 converge to the step S15 which represents the end END of the routine executed by the printed circuit 60 implementing the "command" function.

Advantageously, the routine is iterated according to predetermined cycles. A cycle corresponds to a frequency of realization of the routines and can be predetermined during the implementation of the "control" function of the printed circuit 60. For example, the cycles can evolve according to parameters recorded by the printed circuit board 60. and by way of non-limiting example, a routine cycle with a high frequency is applied when the LAMP_STATE ignition state is "ON" (lamp on) and a lower routine cycle is applied when the state is " OFF "(lamp off).

This embodiment allows the implementation of the control and management of the lighting means 4 by the printed circuits 60 (in particular via the printed circuit 60 having the "control" function). Thus, the bulb device 1 embeds particularly advantageously intelligence allowing autonomy of operation, a reduction in power consumption, optimization of the power supply and preservation ("use according to the recommended conditions") of the lighting means 4.

The "command" function can, in one embodiment, be implemented via a "DMTF" type code (Dual-Tone Multi-Frequency). This implementation is based on a transducer device capable of receiving signals composed of a combination of frequencies used for telephony and transmit them to an electrical device of the "socket" type. The implementation by DMTF makes it possible to program the "control" function of the printed circuit 60 via an analog output of "micro" type electronic devices.

The light sensor 26 measuring the luminosity LUM is an infrared photodiode type infrared light sensor capable of detecting light waves greater than a wavelength of 750 nm. Indeed, this range of wavelengths is strongly represented (in proportion) in the solar spectrum, especially at the end of the day (start of lighting of the lamp) and at the beginning of the day (end of ignition), which allows a more precise detection of the dusk and the sunrise. Thus, the choice of this sensitivity wavelength range of the sensor, which is further removed from the spectral emission band of the lighting means 4 as will be seen later, is advantageous. With reference to FIG. 3A, the characteristics of the infrared light sensor used in the bulb device 1 and, in this case with the curve 302, the conventional spectral sensitivity of such a sensor according to FIG. wavelengths relating to light waves. The illumination means 4 produces no light of light radiation with wavelengths greater than 750 nm in order to prevent the lighting means 4 from interfering with the light waves picked up by the sensor. of infrared light placed, it is recalled, in the base 2 and thus close to the lighting means 4. FIG. 3B illustrates the luminous efficiency perceived by the human eye in the light of the day called "photopic vision" (curve 306), and in night vision called "scotopic vision" (curve 304), as a function of the wavelength relative to the light waves. It is observed here that the luminous efficiency is optimal in night vision for the light waves of a wavelength near 500 nm.

According to FIGS. 3A and 3B, it is appropriate that the light source of the lighting means 4 offers a good compromise between: a low emission of infrared rays (wavelengths greater than or equal to 750 nm), and

a high light radiation power in the vicinity of a wavelength of 500 nm. FIG. 3C illustrates the radiation power relative to wavelengths between 400 nm and 750 nm of three "LED" (light-emitting device) type light sources with different color temperatures:

curve 308 represents the radiation power for an LED with a color temperature between 2600K and 3700K,

curve 3 represents a second LED light source with a color temperature between 3700K and 5000K, and

curve 312 illustrates a third LED light source with a color temperature between 5000K and 8300K.

It is observed that the curves 310 and 312 of the LED light source have a maximum peak of radiation power for a wavelength around 450 nm (adapted for scotopic vision) and a radiation power of less than 4% for a 750 nm wavelength (adapted to not interfere with the detection of the light sensor 26). Curve 308 for its part has a lower radiation power for a wavelength around 450 nm and a radiation power greater than 4% for a wavelength of 750 nm. It is therefore preferable to use, for the lighting means 4, at least one light source of "LED" type with a color temperature preferably between 3000K and 5000K (curve 310) or between 5000K and 8300K (curve 312) to ensure efficient illumination in scotopic vision and at the same time, limiting infrared interference for the light sensor.

Advantageously, the upper portion 24 of the base 2 is composed of a red material, translucent, able to let the natural light outside in the chamber of the base 2 of the bulb device 1 in the range of red and infrared. close. Preferably, the material is translucent for the wavelengths greater than 750 nm from the external natural light so that the brightness sensor housed in the base 2 can capture these light rays necessary to measure a level of light intensity, by filtering lower wavelengths. For this purpose, according to a possible embodiment of the bulb device 1, the upper portion 24 of the base 2 is made of a material consisting of "PolyMethylMethAcrylate" better known as PMMA, tinted red. With such a material for the upper part 24 and with a lighting means 4 minimizing infrared interference (as previously described), the brightness sensor of the printed circuit 60 essentially measures the infrared radiation from the natural light.

However, according to another possible embodiment of the bulb device 1, the upper portion 24 of the base 2 is not translucent and then an opening is provided shaped on the upper part 24 so as to let the natural light outside to 2. In this way, the brightness sensor placed in the base 2 also captures the infrared rays.

Still as an example, in the context of the application of the bulb device 1 of the invention to public lighting, the method can also be preconfigured to light in daylight at specific times. Thus, operators in charge of the maintenance of public lighting can for example check the proper functioning (lighting of the light sources) of the lighting means 4 of the bulb device 1 constituting the public lighting park.

According to another aspect of the invention (which is sufficiently advantageous in itself to envisage a separate protection), the bulb device 1 comprises an orientable pedestal 3 allowing variation of inclination and orientation of the illumination means 4 with respect to the base 2. Such characteristics are particularly suitable for directing the lighting means 4 comprising a light source whose light beam is directional. The swivel base 3 has a shaped passage (described below) providing the crossbar of at least one electrical connection of the lighting means 4 to the printed circuits 60 of the base 2.

Referring now to FIG. 1, the base 2 comprises:

an upper portion 24 having the recess for receiving in particular the printed circuits 60, and

a lower part 22 comprising for example a thread (or alternatively any connection means, for example by "bayonet" snap-fastening) for the electrical connection of the bulb device 1. The swivel base 3 consists of a first sleeve 32 of generally cylindrical shape. The first sleeve 32 is shaped so as to cooperate with the end 24C of the upper portion 24 of the base 2. Such cooperation can be achieved at a contact zone between a portion of the inner surface of the first sleeve 32 and an outer surface of the upper portion 24 of the base, preferably at the end 24C. By way of non-limiting example, the coupling is achieved by means of a prominence of the inner end edge of the sleeve 32 (not shown in the figure) cooperating with a gutter arranged along the end 24C of the base 2. In this way, the two elements are associated and slide relative to each other along the cooperation of the prominence of the sleeve 32 with the gutter 24C end.

Referring to Figure 4A, there is shown a front view of the end 24C of the upper portion 24 of the base 2 in an exemplary embodiment. The end 24C here has a base of generally circular shape including a gutter 500 and grooves 502 disposed in the bottom of the gutter 500. According to the aforementioned example of the coupling of the base 2 and the first sleeve 32, the prominence of the sleeve 32 (not shown in the figures) comprises grooves on the circumference of its contact zone with the gutter 500 of the end 24C. These grooves are preferentially opposed to the grooves 502 of the groove 500. Thus, the grooves are shaped in opposition in order to:

- Allow a rotation of the cooperation (rotation of the sleeve 32 relative to the base 2), and

- initiate a rotation, in increments, by a user (rotation graduated by the grooves).

For purely illustrative purposes, the opposition of the grooves makes it possible to obtain a mobile (possible rotation) cooperation with a mechanical resistance when positioning at a certain selected angle of the sleeve 32 with respect to the base 2, which resistance thus maintains the orientation angle fixed between the base 2 and the lighting means 4 more rigorously than a free cooperation (without flute).

Referring to Figure 4B, there is illustrated a partial view of the end 24C according to the embodiment shown in Figure 4A. There is the gutter 500 with the grooves 502 in the bottom of the gutter 500. In this example of the invention, the grooves 502 are in the form of half-spheres (which are also found in opposition on the inner surface first sleeve 32, not shown here). However, will understand that the splines can take any other form allowing a rotation of the first sleeve 32 with respect to the end 24C.

Referring now to Figure 1, this illustrated embodiment also shows the first sleeve 32 with a portion of its central area having a preformed and polygonal shape 38A. This shape 38A may be hollow or protruding relative to the surface of the central zone of the sleeve 32. The polygonal shape 38A is shaped so as to cooperate with a corresponding shape 38B and has at least part of the surface of another element of the orientable base 3 (such as for example a second sleeve 34 described below). The first sleeve 32 has a first opening 37 adapted to receive a fastening element 36 intended to secure the elements making up the orientable base 3. Preferably, the opening 37 is disposed in the center of the generally cylindrical shape of the first sleeve 32 (FIG. to allow a rotation of the sleeves 32 and 34 relative to each other as described below). The first sleeve 32 also has a second opening 31 adapted to receive a conduit 33 for the passage of electrical connections (not shown in the figures) intended in particular for supplying the lighting means 4 via the printed circuits. 60 of the base 2.

In an advantageous embodiment, the orientable base 3 comprises a second sleeve 34, of frustoconical general shape, positioned in the same axis as the first sleeve 32. This frustoconical general shape (illustrated in FIG. 9) is like a cylinder or a cone , limited by an upper plane PI and a lower plane P2, these two planes being nonparallel. The geometry of the second sleeve 34 then makes it possible to form a bend between the transverse axis of the base 2 and the transverse axis of the lighting means 4. As a function of the angle between the two aforementioned non-parallel planes of the second sleeve 34, the orientable base 3 has a more or less important angle of elbow. For example, the bend angle can be between 0 and 20 ° to orient the lighting means 4 along an axis inclined between 0 and 20 ° relative to that of the base 2 and thus direct more precisely a directional beam of light of the bulb device 1. Thus, in an exemplary implementation, it can be provided different types of second sleeve 34 conferring different respective angles of elbow (defined by the angle between the planes PI and P2), for example, 5 °, 10 °, 15 ° and 20 °. At the editing, a installer may choose a sleeve 34 adapted and in particular conferring an angle of elbow (for example 15 °) suitable for orienting the light beam of the bulb device to a selected surface (as shown in Figure 8). As previously described, at least a portion of the central surface of the second sleeve 34 has a preformed and polygonal protuberance or recess 38B cooperating with the homologous shape 38A of the first sleeve 32. Similar to the first sleeve 32, the second sleeve 34 has at least an opening in the form of a conduit 39 for receiving and cooperating with the fastening element 36. For example, the inner surface of the conduit 39 is threaded so as to cooperate with the fastener 36 which, for example, is a screw. The conduit 39 is preferably placed in the center of the cylindrical surface of the second sleeve 34. In addition, the conduit 33 also has an opening in the second sleeve 34 (not shown in the figures) to ensure the passage of electrical connections previously cited. In addition, the second sleeve 34 has means 35 for fixing the lighting means 4 to the orientable base 3.

The second sleeve 34 is integral with the lighting means 4 (without the possibility of rotation of one relative to the other). Similarly, in this embodiment, the second sleeve 34 is secured to the first sleeve 32 (without the possibility of rotation relative to each other) and the shape of the second sleeve 34 then imposes the inclination of the means 4 relative to the first sleeve 32, and thence, with respect to the base 2 and the socket when the bulb device is mounted. Thus, the angle of inclination of the lighting means 4 relative to the base is predetermined.

However, in a further variant, it may be chosen, for example, to refine the angle of inclination of the lighting means 4 on site. Thus, according to another embodiment, the shapes 38A and 38B according to which the first sleeve 32 and the second sleeve 34 of the orientable base 3 cooperate, are circular in shape. Such an embodiment is suitable for implementing a possible rotation of the first sleeve 32 relative to the second sleeve 34. In such an embodiment, the axis of rotation of the two sleeves relative to each other is formed by the cooperation of the fixing element 36 with the duct 39 (which, it is recalled, are centered with respect to the general cylindrical shape of the sleeves). In this mode of embodiment, it is possible to provide a fastening element 36 with a hollow transverse structure thus forming an internal conduit to the fastening element 36. The internal conduit then makes it possible to ensure the passage of the electrical connections between the lighting means 4 and the printed circuits 60 and this, without damaging the electrical connections nor hindering manipulation of rotations of one sleeve relative to the other.

Referring now to Figure 5 illustrating an exemplary sectional view of the assembled bulb device 1. On the one hand, it can be clearly seen that the first sleeve 32 is in contact with the end 24C of the base 2. On the other hand, it can be seen that the first sleeve 32 and the second sleeve 34 of the orientable base 3 are joined together through the cooperation of the fixing element 36 with the duct 39. In this example of the invention, there is shown the angle 70 formed between the transverse axis of the lighting means 4 and the axis transverse of the base 2, which angle derives from the angle of the general shape of the second sleeve 34.

Referring to Figure 6, there is illustrated a second example of a sectional view of the bulb device 1 assembled at an orientation angle different from that shown in Figure 5. The orientation base 3 here has an angle 80 between the transverse axis of the lighting means 4 and the transverse axis of the base 2. Several variants are possible to adapt the orientation angle of the kind:

a first variant consists in using a second sleeve 34 with a cone angle equal to the desired angle 80, or

a second variant aims (when the cooperation 38A and 38B of the sleeves has a circular base shape) to apply a rotation of the second sleeve 34 (of frustoconical shape) relative to the first sleeve 32. For example, to go from the configuration illustrated in FIG. 5 to the configuration shown in FIG. 6, a rotation of 180 ° has been applied to the second sleeve 34 relative to the first sleeve 32 of the orientable base 3. In addition to the distance applied between the means of 4 and the printed circuit boards 60, the sleeves 32 and 34 of the orientable base 3 may be composed of a thermally insulating material in order to further limit the exposure of the printed circuits 60 of the base 2 to the high temperatures inherent in the operation of the medium. lighting 4. Referring now to Figure 7A which illustrates a sectional view of another possible embodiment of the bulb device 1. Here, the swivel base 3 has a hinge about an axis 90 and a single printed circuit 60 in the base 2. In this embodiment, the base 2 is composed of a conventional material (metal, plastic, etc.). The base 2 is therefore not translucent and, as previously described, an opening 96 may be shaped on the upper part in order to allow the external natural light to enter the enclosure formed by the base 2. According to this embodiment, the first sleeve is in the form of a first ear 92 and the second sleeve in the form of two ears 94.

The first ear 92 is disposed between two homologous lugs 94 and held by an axis 90 in a hinge connection, which allows a pivoting rotation of the lighting means 4 relative to the base 2.

Referring to Figure 7B, there is illustrated another sectional view of the embodiment shown in Figure 7A. Here is shown the cooperation of the ears 92 and 94 allowing articulation around the axis 90. In this embodiment, the axis 90 is arranged to receive and ensure the passage of electrical connections between the means of lighting 4 and the printed circuit 60 of the base 2. For purely illustrative purposes, the axis 90 has a hollow structure and has a first opening on part of its circumference at the level of the ear 92 and at least a second opening on its circumference at the ears 94. In this way, the electrical connections are likely to be passed through the first opening (ear 92, output of the base 2), then within the structure of the axis 90 before emerging by the second opening (ears 94, at the input of the lighting means 4).

Referring now to Figure 8 which illustrates an implementation of the bulb device 1 in an example of outdoor environment 800 and more particularly at a public lighting device 802 type "floor lamp".

Such a lamppost 802 can target the lighting on the ground of a targeted surface (surface 804) such as for example a pedestrian crossing. The surface 804 to be illuminated then covers:

the width of sidewalks 808, the width of Route 806, and

the length 807 of the pedestrian crossing.

The use of a light source with a directional beam is particularly suitable in this situation. When installing the bulb device 1, the installer realizes Γ light bulb device 1 apartment with lamppost socket 802. This apartment provides a power supply to the bulb device 1 and a mechanical holding of the part bottom 22 of the base 2 with the lampholder bushing 802.

However, after pairing, for example by rotation of the base 2 in the lampholder sleeve 802, it is possible that the beam is not in a position allowing the illumination of the surface 804 on the ground, but rather oriented towards the sky by example.

Advantageously, the installer can vary the direction of the beam of the lighting means 4 of the bulb device 1 by rotating the first sleeve 32. The rotation of the first sleeve 32 relative to the base 2 (around the X axis at the angle 810 of Figure 8) makes it possible to angularly catch an incorrect position of the lighting means 4 relative to the socket of the lamppost, following the rotation of the base of the bulb device 1 in the socket for its connection and its connection to the lamppost. Then, the rotation of the second sleeve 34 with respect to the first sleeve 32 (rotation around the Y axis of FIG. 8) makes it possible to adapt the orientation angle of the beam, without affecting the pairing of the device. bulb 1 with lampholder lampholder 802.

Thus, the cooperation of these two sleeves 32 and 34 with the other elements of the bulb device 1 advantageously allows a connection in rotation in azimuth and in elevation (ground view) of the lighting means 4 relative to the base 2.

The bulb device 1 can then be adapted to any type of street lamps and / or surfaces to be illuminated.

Referring again to Figure 1, the bulb device 1 according to this embodiment has an end of the lighting means 4 fixed to the orientable base 3. At the other end of the lighting means 4 is arranged a hood 5. The lighting means 4 consists here of a light source 406 comprising at least one LED 406a. Optionally, a plurality of LEDs can be arranged in the same plane so that the light source 406 forms a strip of LEDs 406a. The LEDs 406a are electrically powered by an electrical connection connected to at least one printed circuit 60 remotely located in the base 2. This connection provides the power supply that LEDs require for their operation. In this way, the power supply (and therefore the luminous intensity) of the LED diodes can be controlled from at least one printed circuit board 60. It is recalled that the conduit 33 is able to ensure the passage of the electrical connections between the lighting means 4 (and therefore the light source 406) and at least one printed circuit 60 of the base 2.

Advantageously, the light source 406 of the lighting means 4 comprises at least one temperature sensor 406b. The sensor 406b measures the temperature of the light source 406 and / or its near environment in order to record information relating to the heating inherent in the operation of this light source 406. The information is transmitted to at least one printed circuit 60 via an electrical connection. which can follow the same path as the electrical connection of the power supply of the light source 406.

In addition, the lighting means 4 also consists of a fixing plate 408 ensuring the maintenance of the light source 406 in contact with a heat sink 402. The dissipator 402 is advantageously composed of a thermally conductive material (good heat dissipation) such as aluminum and this in order to limit heating of the light source 406 in operation. The dissipator may adopt a truncated cylinder shape (three quarters in the example shown in Figure 1) with a fin internal structure so as to maximize the contact surface of the heat sink 402 with the ambient air. In addition, the heat sink 402 may have a preformed location 402a provided to receive the light source 406.

In one possible embodiment, a thermally conductive material 404 may be interposed between the preformed location 402a and the light source 406. The presence of the thermally conductive material 404 increases the clamping pressure of the assembly:

sink 402, light source 406, and

fixing plate 408.

The increase in the clamping pressure of this assembly is inherent to the intermediate presence of the thermo-conductive material 404 which thus improves the heat transfer (by thermal conduction) of the assembly (in particular from the light source 406 to the heat sink 402). For purely illustrative purposes, the thermally conductive material 404 may be:

gel (which can be found in the form of a seal) of silicone, or

thermo-conductive foam.

Preferably, the thermo-conductive material 404 used is the thermally conductive foam because it is more suitable to allow replacement of the light source 406 (no mechanical attachment of the light source and the heat sink unlike a silicone use). Thus, one can retain the structure of the bulb device and change on the other hand that the light source, particularly advantageous.

At the heat sink 402, a passage 402b is provided for the electrical connections of the light source 406 and the temperature sensor 406b so as to ensure their passage to the printed circuits 60 of the base 2 (and this via the conduit 33).

The lighting means 4 also comprises an optical element 410 diffusing the light emitted by the light source 406. For this purpose, the optical element 410 is shaped to diffract the directional light beam emitted by the light source 406 so as to illuminate shape surfaces:

straight,

concave, and / or

convex.

For this purpose and according to the aforementioned embodiment where the light source 406 comprises an LED strip 406a, the optical element 410 may have a plurality of optical lenses 410a arranged to diffract the directional light beams of each LED 406a LEDs . Thus, the beam of the light source 406 can be more or less diffracted by the optical element 410 in order to be focused on a surface to be illuminated. particular (having one of the aforementioned geometric shapes according to given dimensions). By way of nonlimiting example, the beam of the light source 406 is diffracted by the optical element 410 in a rectilinear shape to the dimensions of the pedestrian crossing shown in FIG. 8. Moreover, the optical element 410 can be shaped to obtain a beam of uniform brightness then having the same level of brightness over approximately the entire area illuminated by the light source 406

In addition, the optical element 410 has openings 410b for the passage of fixing means 450 which cooperate with the corresponding orifices 402c of the heat sink 402 to ensure the joining of the assembly:

sink 402,

thermo-conductive material 404,

light source 406,

fixing plate 408, and

optical element 410.

In addition, the lighting means 4 comprises a trim 412 superimposed on the optical element 410 and thus hiding the fixing means 450. Such a hubcap 412 furthermore allows the assembly of elements assembled within the lighting means 4 (elements 402, 404, 406, 408, 410 and 412) conforms to the geometry (of generally circular shape) of the orientable base 3 and the cover 5.

The hood 5 of the bulb device 1 has a circular main part 52 with a border 54 perpendicular to the plane of the main part 52 on at least a part of the circumference of the main part 52. Openings 55 are arranged in the main room 52 to receive fastening means 56. The fastening means 56 are provided to cooperate with the cavities 402c for fixing the heat sink 402 and thus ensure the fastening of the cover 5 with the lighting means 4. As well as a rim 64 of the sleeve 34, the edge 54 of the cover 5 envelopes at least a portion of all the elements 402, 404, 406, 408, 410 and 412 of the lighting means 4 in order to maintain the cohesion of this assembly. It will be understood that these examples of embodiments are purely illustrative and not limiting. Indeed, other embodiments than those described above may be considered in the context of the present invention, as will be apparent to those skilled in the art. By way of example, the spectral emission ranges of the LEDs given above, although advantageous, are subject to variations. It can indeed be retained that a warm urban lighting remains in a wavelength range greater than 500 nm (with a color temperature therefore colder).

Claims

Bulb device (1) comprising at least one lighting means (4) and a base (2), characterized in that it comprises at least one printed circuit (60) internal to said bulb device (1). ) and housed in the base (2), for regulating a power supply of said lighting means (4),

and in that, the device further comprising at least one sensor (26; 406b), the printed circuit (60) comprises at least one microcontroller recovering signals from the sensor and setting regulation instructions for the power supply of said means lighting (4) according to said signals.

Bulb device (1) according to claim 1, characterized in that the printed circuit (60) comprises at least one electrical connection means (60a) for receiving a power supply from the base (2) and regulating said power supply for said lighting means (4).

3. Bulb device (1) according to one of the preceding claims, characterized in that it comprises at least one temperature sensor (406b) of the lighting means (4) transmitting to the printed circuit (60) information of the temperature of the lighting means (4).

4. Bulb device (1) according to one of the preceding claims, characterized in that it comprises at least one brightness sensor (26) transmitting to the printed circuit (60) information relating to natural light surrounding the device of bulb (1).

5. Bulb device (1) according to claim 4, characterized in that the brightness sensor (26) is housed in the base (2) of said bulb device (1), said cap being made of a translucent material at a wavelength range greater than 750 nm, and / or having an opening (96) for sensing said natural light.

6. Bulb device (1) according to one of the preceding claims, characterized in that said lighting means (4) comprises a light source (406) emitting in a spectrum between 400 and 700 nm.

Bulb device (1) according to one of the preceding claims, characterized in that the printed circuit (60) comprises a power supply control program of the lighting means (4) according to a plurality of time ranges. at least corresponding to:

an extinction of the lighting means (4) on a first range, and

- Lighting of the lighting means (4) at a chosen level of light intensity, on a second range.

8. Bulb device (1) according to claim 7, characterized in that the microcontroller determines said chosen level of light intensity according to said sensor signals.

9. Bulb device (1) according to one of claims 7 and 8, characterized in that the printed circuit controls a variable light intensity level as a function of time sub-ranges of said second range.

10. Bulb device (1) according to one of the preceding claims, characterized in that it further comprises an orientation base (3) forming an interface between the lighting means (4) and the base (2). ).

1 1. Bulb device (1) according to claim 10, characterized in that said orientation base (3) comprises at least a first sleeve (32) integral with the lighting means (4) and rotatable for an angular adjustment of the lighting means (4) relative to the base (2) around a main axis (X) of the base (2).

12. Bulb device (1) according to claim 1 1, characterized in that said first sleeve (32) is rotatable relative to the base (2) according to a coupling forming a mechanical resistance in rotation.

Bulb device (1) according to claim 12, characterized in that said rotational mechanical resistance is obtained by a cooperation of opposite splines (502), which splines are formed at the periphery of said first sleeve (32) and said base (2).

14. Bulb device (1) according to one of the preceding claims, characterized in that said orientation base (3) comprises at least one second sleeve (34) of cylindrical or frustoconical shape delimited by two planes (PI, P2) non-parallel, for an angular adjustment of the lighting means (4) relative to the base (2), about an axis (Y) perpendicular to a main axis of the base (2).

15. Bulb device (1) according to one of the preceding claims, characterized in that said orientation base (3) thermally insulates said printed circuit (60) with respect to said lighting means (4).

16. Bulb device (1) according to claim 15, characterized in that said first and second sleeves of the orientable base (3) are composed of a thermally insulating material.

17. Bulb device (1) according to one of the preceding claims, characterized in that said lighting means (4) comprises a light source (406) directed beam.

18. A method of regulating the power supply of a light bulb device (1) according to one of the preceding claims, wherein at least one printed circuit (60) is provided inside said light bulb device (1) and accommodated. in a base (2) of the bulb device, for regulating a power supply of a lighting means (4) of said bulb device,

and in that, the device further comprising at least one sensor (26; 406b), the printed circuit (60) is provided with at least one microcontroller recovering signals from the sensor and setting regulation instructions for the power supply of said lighting means (4) according to said signals.

19. The method of claim 18, characterized in that the power supply of the lighting means (4) is regulated according to a plurality of time ranges corresponding to at least:

an extinction of the lighting means (4) on a first range, and

20. The method of claim 19, characterized in that the method comprises the steps:

- reading (V9) a time variable (TIMER), and

and comparing (T 10, T12) the time variable with at least one threshold value to identify at least one transition between two sub-ranges of the second time range.

Method according to one of claims 19 and 20, characterized in that a brightness (LUM) of the environment of the bulb device (1) is measured (VI) and compared with a first threshold value (T2), and in that the beginning of the second range is determined by an ambient brightness (LUM) of the bulb device (1) less than said first threshold value.

22. Method according to one of claims 19 to 21, characterized in that a brightness (LUM) of environment of the bulb device (1) is measured (VI) and compared to a second threshold value (T2), and in that the end of the second range is determined by an ambient brightness (LUM) of the bulb device (1) greater than said second threshold value.

23. Method according to one of claims 18 to 22, characterized in that a temperature (T) of the illumination means (4) of the bulb device (1) is measured (V6) and compared to a third value threshold (T7), and in that a level of luminous intensity of the lighting means (4) is lowered if the measured temperature (T) is greater than said third threshold value.

24. Computer program comprising instructions for implementing method according to one of claims 18 to 23, when the program is executed by processor.