Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/10—Controlling the intensity of the light
  • H05B45/14—Controlling the intensity of the light using electrical feedback from LEDs or from LED modules
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/20—Controlling the colour of the light
  • H05B45/24—Controlling the colour of the light using electrical feedback from LEDs or from LED modules

Definitions

• the present invention relates to a thermal optimization system for the efficiency of a light emitting device.
• LED Light Emitting Diode
• a passive cooling system mainly consists of a release device that allows the dissipation of heat, generated by the junction characteristic of a LED device, through phenomena of conduction and/or convention and in small part of irradiation too.
• thermoplastic composites with conductive fillings which allows a greater thermal conductivity and lower thermal expansion coefficients than those of the usual metallic materials characterizing dispersal devices.
• the efficiency of these systems depends mainly on the surface dimension and on particular shapes of the cooling devices in order to involve the bigger amount of gas or liquid for cooling.
• lamps consist of LED devices mounted on metal plates facing the outside of the bulb, immersed in an inert liquid that cools the components, allowing rapid cooling of the system.
• An active cooling system known is characterized by a mechanical device such as an electric fan or a diaphragm pump, physically associated to a device for dispersion.
• the aforesaid mechanical device produces a flow of air through the device associated dispersion, allowing an effective dissipation of the heat produced, but leading to a decrease of the estimated service life of the device associated LED, an increase in the power consumption of the system by reducing the reliability and a significant noise related to the use of these specific mechanical devices.
• the aforesaid known systems optimization thermal and light do not allow an adequate dissipation of the heat produced by the LED device, especially when the driver power of such devices is characterized by an increase of the input current applied, subjecting the LED to an electrical stress that leads to a decrease of the luminous efficacy of the same.
• a thermal dissipation insufficient exposes the LED device to a mechanical stress, damaging the junction characteristic of the LED device, causing rupture of the entire element, the internal delamination of the welding point, and the yellowing of the lenses of the optical system.
• the above optimization systems do not prevent the decay of the light flow in conditions of thermal stress, which occurs with an increase in ambient temperature and/or the junction temperature of the LED device, not allowing a use of "1" said device outside of the region operation for which it was designed, reducing by about seven times the estimated life of this device LEDs.
• Purpose of the present invention is therefore to solve the above problems of the prior art by providing a system for optimization of a light emitting device, which allows to improve the thermal efficiency and simultaneously increase the luminous efficiency of the device itself.
• a further object of the present invention is to provide an optimization system compatible with all types of devices emitting known.
• FIG. 1 is a view of a preferred embodiment of the optimization system of a light emitting device according to the present invention
• FIG. 2 shows a second simplified embodiment of the optimization system of a light emitting device according to the present invention
• Figs. 3 and 4 show the graphs relating to the light emission, as a function of time, of a light emitting device connected to the system optimization according to the present invention, and the same light emitting device not connected to said system optimization, and
• - Figs. 5 and 6. show the graphs relating to thermal emission, as a function of time, of a light emitting device connected to the system optimization according to the present invention, and the same light emitting device not connected to said system optimization. Referring to the Figures, is illustrated and described a preferred embodiment of the present invention.
• a light emitting device 2 such as a light emitting diode LED, or other suitable device, comprises at least one electronic instrument power 3 as a static converter chopper, a regulator buck converter, a boost converter, or other appropriate means .
• the above system 1 comprises at least one system state detector 5, which an amperometric sensor or other suitable sensor, adapted to detect the operating conditions of the light emitting device 2, determining at least one value of the ratio between a voltage and a supply current supplied to the device 2 by a constant current driver 6 and send it to a control unit 4, which an electronic circuit microprocessor regulation or other unit suitable control.
• a system state detector 5 which an amperometric sensor or other suitable sensor, adapted to detect the operating conditions of the light emitting device 2, determining at least one value of the ratio between a voltage and a supply current supplied to the device 2 by a constant current driver 6 and send it to a control unit 4, which an electronic circuit microprocessor regulation or other unit suitable control.
• the optimization system 1 comprises at least one control unit 4 suitable to acquire in input, from the system state detector 5, the above ratio value by establishing an output value of ratio lower than previously acquired; report identifies the value of the type 2 light emitting device connected to the system 1, representing an operation information that the unit 4 sends to the electronic power 3.
• the electronic tool of power 3 converts the voltage levels and supply current supplied from the driver to the device 2 in 6 levels of voltage and current according to the lower ratio . value received from the operating unit 4.
• This mode of action of the instrument 3 allows the power of the light emitting device 2 with a voltage and with a .Supply current lower than those provided by the aforementioned driver 6, improving the thermal efficiency of the device 2 and ensuring a stable luminous flux, during the period of use of the device 2.
• the instrument 3 in the device induces a second surge of intensity, frequency and duration suitable to determine a cooling of the junction characteristic of the device 2, favoring the thermal management of the device 2 itself.
• the system 1 is compatible with all types of devices emitting known, such as high power devices, high voltage, traditional, etc.
• the optimization system 1 can be simplified as comprising only an electronic instrument power 3 suitable to adjust the voltage and the supply current provided by the driver 6 connected to the light emitting device 2, converting them into a voltage and a current of lower level according to a ratio value initially known, characterizing the specific light emitting device (led or different kinds) used.
• the above experimental conditions are: temperature constant in the absence of ventilation equal to 22 °C; supply voltage and supply current, provided by the driver 6 connected to the light emitting device 2, respectively equal to 24Vdc and 790mAh; dispersion device in aluminum associated with the light emitting device 2 with a size of 100 mm x 88 mm x 35 mm and weight of 220 grams.
• the light emitting device 2 presents optimized light output equal to 3030Lux and a thermal emission equal to the room temperature setting of 22 °C, and the light emitting device 2 has a non-optimized light output equal to 2820Lux and thermal emission tax equal to the ambient temperature of 22°C, the last measurement interval, the light emitting device 2 presents optimized light output equal to 2910 Lux and thermal emission equal to 53°C.
• the light emitting device 2 is not optimized in the above measuring range is cut off, it is significant the penultimate interval measuring device 2 has not optimized light output equal to 2700Lux and thermal emission equal to 73 °C.
• the device 2 is optimized still characterized by a thermal emission stable equal to 53°C, ensuring high thermal efficiency and simultaneously a high luminous efficiency of the device 2.
• the document US4038914A relates to a control system of the light emission of an LED , characterized by a feedback circuit on the value of the temperature Ta of the environment in which it operates the LED .
• This control system is characterized by a processing unit of the temperature , absent in the optimization system object of this invention , which detects the temperature Ta characteristic of the environment in which is inserted the LED and of the variation of this value as a function of temperature Ta of the light output of the LED.
• the LED is connected to a constant current source able to modify the current through the LED depending on the information received from the feedback circuit relatively to the detected temperature TA of the environment in whic " h is inserted the LED , after switching LED and the relative light output emitted by the LED .
• this control system is connected across the LED to facilitate the detection of the maximum voltage Vf (forward voltage) and therefore of the relative maximum current that can pass through the LED .
• the proposed invention in the patent application in question , refers instead to a system optimization characterized by comprising at least one electronic instrument of power ( 3 ) adapted to convert , in function of at least one operating condition of operation of said device photoemitter ( 2 ) , at least one peak power of said light emitting device ( 2 ) and to induce at least one overvoltage of very short duration in said light emitting device ( 2 ) ; said brief overvoltage, induced by said electronic instrument of power ( 3 ) on said green light emitting device ( 2 ) , is adapted to determine a cooling of the junction of said light emitting device ( 2 ) .
• the operating condition of operation or an initial value of the ratio between the supply voltage and the supply current , provided by the power driver traditional ( 6 ) to the light emitting device ( 2 ) is detected by a System state detector ( 5 ) that sends that information to a control unit ( 4 ) , said control unit ( 4 ) provides power to the electronic instrument ( 3 ) a value of the ratio to the initial value of the ratio acquired by the state detector ( 5 ) allowing the optimization system to provide power to the light emitting device ( 2 ) with a voltage and with a supply current optimal than those provided by the driver ( 6 ) traditional feed , improving the thermal efficiency of the light emitting device ( 2 ) and ensuring respect to the system of document US4038914A , a luminous flux stable during the period of use of the light emitting device ( 2 ) .
• the document WO2009095853 refers instead to a system and to a method for detecting the junction temperature of an LED and control the behavior of the LED , by monitoring the mafximum voltage present across the LED , through the identification of a range characterized by an extreme upper represented by the value of the maximum voltage and a lower extreme represented by the value of the minimum voltage .

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Cited By (2)

Citations (4)

• 2013
  • 2013-03-18 IT IT000211A patent/ITTO20130211A1/it unknown
• 2014
  • 2014-03-13 WO PCT/IT2014/000071 patent/WO2014147653A1/en active Application Filing

Patent Citations (4)

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