WO2009028863A2 - Procédé et appareil de régulation thermique d'un dispositif del - Google Patents

Procédé et appareil de régulation thermique d'un dispositif del Download PDF

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Publication number
WO2009028863A2
WO2009028863A2 PCT/KR2008/005008 KR2008005008W WO2009028863A2 WO 2009028863 A2 WO2009028863 A2 WO 2009028863A2 KR 2008005008 W KR2008005008 W KR 2008005008W WO 2009028863 A2 WO2009028863 A2 WO 2009028863A2
Authority
WO
WIPO (PCT)
Prior art keywords
led
excess current
thermal control
current
heat
Prior art date
Application number
PCT/KR2008/005008
Other languages
English (en)
Other versions
WO2009028863A3 (fr
Inventor
Tae Sun Jang
Original Assignee
Inix Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from KR20080038350A external-priority patent/KR20090023038A/ko
Application filed by Inix Co., Ltd. filed Critical Inix Co., Ltd.
Publication of WO2009028863A2 publication Critical patent/WO2009028863A2/fr
Publication of WO2009028863A3 publication Critical patent/WO2009028863A3/fr

Links

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]
    • H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
    • H05B45/56—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits involving measures to prevent abnormal temperature of the LEDs

Definitions

  • the present invention relates to thermal control method and apparatus of an LED device, and more particularly, to thermal control method and apparatus of an LED device in which excess current greater than normal current is supplied to the LED device to control a supply time of the excess current.
  • Examples of a lighting apparatus include an advertising board, a traffic light, and an emergency light. Such lighting apparatuses perform a lighting operation or output a signal by emitting light from a light emitting section thereof.
  • an LED lighting Emitting Diode
  • LED lighting Emitting Diode
  • the light emitting section including the LED has an advantage of displaying high brightness with low power consumption.
  • Light emitting devices outputting a variety of colors have been developed and are widely used in the lighting apparatuses such as an advertising board and a traffic light.
  • the lighting device such as an LED ends its lifetime when the emission efficiency thereof is lowered by 70%.
  • the lifetime is determined by the light- emitting duration, but the lifetime remarkably varies due to thermal deterioration resulting from heat generated at the time of emitting light. That is, the lifetime is shortened due to the thermal deterioration.
  • Fig. 1 is a graph illustrating a relation between time t and current I supplied to the
  • the LED device has a structure for continuously supplying current Il smaller than the normal current to emit light and thus has a problem that the lifetime of the LED device is shortened due to the accumulation of heat.
  • Fig. 2 is a graph illustrating a temperature distribution in an LED bonding structure.
  • the temperature forms a peak at a position of the LED 9 and decreases as the distance from the position of the LED 9 increases.
  • a heat radiating plate or other heat radiating fan is used to stabilize the temperature of the LED 9 in the range of 12 0 C to 6O 0 C, which is not a fundamental solution but causes a problem with an increase in volume and cost. Disclosure of Invention Technical Problem
  • a goal of the invention is to provide thermal control method and apparatus of an
  • Another goal of the invention is to provide thermal control method and apparatus of an LED device that can elongate the lifetime of the LED device.
  • Another goal of the invention is to provide thermal control method and apparatus of an LED device that can prevent or minimize the deterioration of an LED and the ac- cumlation of heat.
  • Another goal of the invention is to provide thermal control method and apparatus of an LED device that can reduce the cost and the volune.
  • a thermal control method of an LED device including: applying excess current larger by a predetermined level than normal current to at least one LED; and repeatedly switching supply and interception of the excess current to the at least one LED and controlling a supply time of the excess current to the at least one LED.
  • the supply time of the excess current may be determined such that the at least one
  • an interception time of the excess current may be determined on the basis of an amount of heat emitted from the at least one LED.
  • the at least one LED may be bonded to a base substrate for radiating heat and dispersing heat.
  • a thermal control apparatus of an LED device including: an LED light-emitting section including at least one LED; a power source supplying excess current, which is larger by a predetermined level than normal current of the at least one LED, to the at least one LED; a control signal generator generating a control signal for controlling a supply time of the excess current by supplying and intercepting the excess current; and a switching section connected between the LED light-emitting section and a ground terminal so as to perform a switching operation in response to the control signal.
  • the control signal may be a rectangular wave or a PWM signal.
  • the switching section may include at least one switching element having at least one field effect transistor (FET) or at least one transistor (TR).
  • FET field effect transistor
  • TR transistor
  • the at least one LED may be bonded to a base substrate for radiating heat and dispersing heat.
  • Fig. 1 is a graph illustrating a relation between time t and current I supplied to a known LED device.
  • Fig. 2 is a graph illustrating a temperature distribution in a known LED bonding structure.
  • FIG. 3 is a circuit diagram illustrating a thermal control apparatus of an LED device according to an embodiment of the invention.
  • Fig. 4 is a graph illustrating a relation between time and current supplied to an LED shown in Fig. 3.
  • Fig. 5 is a graph illustrating a temperature distribution in an LED bonding structure having the structure shown in Fig. 3. Mode for the Invention
  • FIG. 3 is a circuit diagram illustrating a thermal control apparatus 300 of an LED device according to an embodiment of the invention.
  • the thermal control apparatus 300 of an LED device includes an
  • the thermal control apparatus may further include a base substrate (indicated by reference mineral 11 of Fig. 5) mounted with the LED light-emitting section 320, the control signal generator 310, and the switching section 300.
  • the base substrate 11 may serve to radiate heat and disperse heat.
  • the LED light-emitting section 320 has a structure in which at least one LED D is connected to at least one resistor Rl. An end of the resistor Rl is connected to a power source and the other end of the resistor Rl is connected to a plus terminal + of the LED.
  • the resistor Rl is a protective resistor for protecting the LED D.
  • the LED light-emitting section 320 may have a structure in which plural connection structures of an LED and a resistor similar to the connection structure of the LED D and the resistor Rl shown in Fig. 3 are connected in parallel.
  • the power source supplies excess current, which is larger by a predetermined level than normal current of the LED, to the LED D.
  • the power source supplies the excess current to the LED D through the resistor Rl.
  • the control signal generator 310 generates a control signal for controlling a supply time of the excess current by supply and interception of the excess current.
  • the control signal generator 310 generates a rectangular wave or a PWM (Pulse
  • the rectangular wave and the PWM signal are generally referred to as rectangular wave.
  • the control signal generator 310 generates the rectangular wave in a program manner and can vary the period and the duty ratio of the rectangular wave. That is, the duty ratio and the period of the rectangular wave can be adjusted.
  • the control signal generator 310 may include a micro processor (MPU: micro-processor unit) controlling the generation of the rectangular wave.
  • MPU micro-processor unit
  • the switching section 330 is connected between the LED light-emitting section 320 and the ground terminal and performs a switching operation in response to the control signal generated from the control signal generator 310.
  • the switching section 330 switches the power source of the LED light-emitting section 320 in response to the control signal to repeatedly turn on and off the at least one LED D of the LED light-emitting section 320 with a predetermined time interval.
  • the switching section 330 may include at least one field effect transistor (FET) or at least one transistor (TR) for fast switching.
  • FET field effect transistor
  • TR transistor
  • the switching section may include a switching element well known to those skilled in the art.
  • the switching section 330 includes at least one resistor R2 and at least one switching element Q.
  • the base of the switching element Q is connected to the resistor R2, the collector is connected to a terminal of the resistor Rl not connected to the LED D, and the emitter is grounded.
  • the switching element Q employs the field effect transistor
  • the gate of the FET is connected to the resistor R2
  • the source is connected to a terminal of the resistor Rl not connected to the LED D
  • the drain is grounded.
  • the switching section 330 also includes only one switching element.
  • the switching section can include the same number of switching elements as the LEDs or a predetermined nunber of switching elements so that one switching element corresponds to a predetermined nunber of LEDs.
  • the switching section may include five switching elements in the one-to-one correspondence, or may two switching elements of which one switching element is connected to two LEDs and the other switching element is connected to three LEDs. The nunber of switching elements connected to the LEDs can be adjusted variously depending on the correspondence type.
  • Fig. 4 is a graph illustrating a relation between time and current supplied to the LED D.
  • Current Il shown in Fig. 4 represents normal current of the LED and current 12 represents excess current larger by a predetermined level than the normal current.
  • the excess current L2 is supplied from the power source.
  • the control signal generator 310 When the control signal generator 310 generates the control signal, the supply time of the excess current 12 is controlled by the fast switching operation of the switching section 330 in response to the control signal.
  • the supply time of the excess current 12 is adjusted on the basis of the fact that the destruction or thermal resistance of the LED is remarkably reduced at the time of instantaneously applying the excess current.
  • the instantaneous excess current 12 supplied to the LED D enhances the efficiency of light, but causes the destruction of the LED due to the accumulation of heat when the supply time is great. Accordingly, the supply time of the excess current 12 is adjusted not to destruct the LED D.
  • the supply time has the unit of ⁇ s (micro second). Then, when the excess current 12 is intercepted, the generated heat is radiated through the base substrate. When the heat is sufficiently radiated, the excess current 12 is applied thereto again. This operation is repeated.
  • the excess current 12 is supplied in a third time interval t3, a fifth time interval t5, and a seventh time interval t7, and the excess current 12 is intercepted in a fourth time interval t4 and a sixth time interval t6.
  • the time lengths of the first time interval tl, the third time interval t3, the fifth time interval t5, and the seventh time interval t7 may be equal to each other or may be different from each other.
  • the time lengths of the second time interval t2, the fourth time interval t4, and the sixth time interval t6 may be equal to each other or may be different from each other. Particularly, when the time lengths of the second time interval t2, the fourth time interval t4, and the sixth time interval t6 are short, that is, when the excess current is supplied again in a state where the heat is not sufficiently radiated, the deterioration and the accunulation of heat may occur. Accordingly, a sufficient time length should be guaranteed.
  • the high-level length of the rectangular wave as the control signal is equal to the supply time length of the excess current 12 and the low-level length of the rectangular wave is equal to the interception time length of the excess current 12. This is natural because the supply and interception of the excess current 12 is controlled by the rectangular wave.
  • the level of the excess current 12 and the supply time and the interception time of the excess current can be controlled to interlock with each other. For example, when the level of the excess current 12 is raised, the supply time length of the excess current 12 can be reduced and the interception time length of the excess current 12 can be reduced.
  • the level of the excess current 12 can vary variously. When the level of the excess current 12 is once determined, the supply time and the interception time of the excess current 12 is controlled. The time may be several tens ⁇ s to several hundreds ⁇ s .
  • the times can be defined by plural experiments. Since a packaging method and an LED bonding structure are different every element and a degree of heat transmission is different every structure, the time values should be acquired from the experiments by characteristics of elements. The experiment result is input to the control signal generator 310 to control the rectangular wave.
  • Fig. 5 is a graph illustrating a temperature distribution in the LED bonding structure.
  • the temperature forms a peak at a bonding position of the LED 9 and decreases as the distance from the bonding position of the LED 9 in the base substrate 11 increases.
  • the temperature of the LED device is stabilized in the range of 13 0 C to 4O 0 C as a whole. Accordingly, since the peak temperature is lowered by 2O 0 C or more, it is possible to prevent or minimize the destruction of the LED due to the deterioration of the LED and the accumlation of heat.
  • Reference numeral 10 represents an LED bonding material which is not described here.

Landscapes

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

Abstract

L'invention concerne un procédé et un appareil de régulation thermique d'un dispositif DEL. Ce procédé consiste à injecter, dans au moins une DEL, un courant d'excès supérieur à un niveau de courant prédéterminé par rapport à un courant normal; à commuter répétitivement l'injection et l'arrêt de ce courant d'excès dans ladite DEL; et à commander la durée d'injection du courant d'excès dans ladite DEL. Selon l'invention, il est possible d'éviter ou de minimiser la détérioration de la DEL et l'accumulation de chaleur, ce qui permet d'accroître la fiabilité de la DEL.
PCT/KR2008/005008 2007-08-27 2008-08-27 Procédé et appareil de régulation thermique d'un dispositif del WO2009028863A2 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
KR20070085972 2007-08-27
KR10-2007-0085972 2007-08-27
KR20080038350A KR20090023038A (ko) 2007-08-27 2008-04-24 엘이디 발광체 열 제어방법 및 장치
KR10-2008-0038350 2008-04-24

Publications (2)

Publication Number Publication Date
WO2009028863A2 true WO2009028863A2 (fr) 2009-03-05
WO2009028863A3 WO2009028863A3 (fr) 2009-05-22

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/KR2008/005008 WO2009028863A2 (fr) 2007-08-27 2008-08-27 Procédé et appareil de régulation thermique d'un dispositif del

Country Status (1)

Country Link
WO (1) WO2009028863A2 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005173523A (ja) * 2003-12-08 2005-06-30 Beyond Innovation Technology Co Ltd Ｌｅｄ駆動用低視覚ノイズのｐｗｍ照明コントロール回路
JP2006222376A (ja) * 2005-02-14 2006-08-24 Seiwa Electric Mfg Co Ltd 電源装置及び照明装置
JP2006301027A (ja) * 2005-04-15 2006-11-02 Avix Inc 色順次式ｌｅｄ駆動回路

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005173523A (ja) * 2003-12-08 2005-06-30 Beyond Innovation Technology Co Ltd Ｌｅｄ駆動用低視覚ノイズのｐｗｍ照明コントロール回路
JP2006222376A (ja) * 2005-02-14 2006-08-24 Seiwa Electric Mfg Co Ltd 電源装置及び照明装置
JP2006301027A (ja) * 2005-04-15 2006-11-02 Avix Inc 色順次式ｌｅｄ駆動回路

Also Published As

Publication number Publication date
WO2009028863A3 (fr) 2009-05-22

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