JP5263503B2 - Light emitting diode lighting device - Google Patents

Light emitting diode lighting device Download PDF

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Publication number
JP5263503B2
JP5263503B2 JP2008203609A JP2008203609A JP5263503B2 JP 5263503 B2 JP5263503 B2 JP 5263503B2 JP 2008203609 A JP2008203609 A JP 2008203609A JP 2008203609 A JP2008203609 A JP 2008203609A JP 5263503 B2 JP5263503 B2 JP 5263503B2
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output
emitting diode
light
power factor
dimming
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JP2010040400A (en
Inventor
寛和 大武
拓朗 平松
博志 寺坂
充彦 西家
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東芝ライテック株式会社
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting diode lighting device improved so that flickers of the light-emitting diode do not occur, even when the load becomes very light-weight by deepened dimming. <P>SOLUTION: The light-emitting diode lighting device includes a rectification direct-current power supply RDC; a power factor-improvement circuit PFI which is constituted to have a boosting chopper as the body and of which the input end is connected to the rectification direct-current power supply; a direct-current converter DCC of which the input end is connected to the output end of the power factor improvement circuit; a light-emitting diode LED which is connected to the output end of the direct-current converter and lighted; a dimming signal output means DSG; and a control means CC which controls at least one output of the direct-current converter and the boost chopper of the power factor improvement circuit, corresponding to the dimming signal output from the dimming signal output means, stops operation of the power factor improvement circuit when light output of the light-emitting diode is reduced to a prescribed level, and controls so that output of the rectification direct-current power supply is directly supplied to the direct-current converter. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a light emitting diode lighting device capable of lighting a light emitting diode in a dimmable manner.

  A light-emitting diode lighting device that lights a light-emitting diode so as to be dimmable is known (for example, see Patent Document 1). In the lighting circuit described in Patent Document 1, an AC rectified voltage is boosted by a boost chopper, smoothed and supplied to a plurality of light emitting diodes connected in series, and this is lit and controlled by controlling the boost chopper. In addition to being able to shine, the power factor can also be improved.

Japanese Patent Application Laid-Open No. 11-066771

  However, when a power factor correction circuit mainly composed of a boost chopper is used, appropriate control operation is performed for a certain range of loads, so dimming is possible, but deep dimming makes the load extremely light. When this occurs, an abnormal control operation occurs and intermittent oscillation occurs, resulting in fluctuations in output. When a DC converter is further provided after the boost chopper, the DC converter may be in a state where it can be operated so as to perform output stabilization control. However, the control operation is a power supply fluctuation, that is, an output fluctuation of the power factor improvement circuit. If it is impossible to follow the above, there is a problem that the light output of the light emitting diode fluctuates and flickering occurs.

  An object of the present invention is to provide an improved light emitting diode lighting device so that flickering does not occur in the lighting of the light emitting diode even when the light control becomes deep and the load becomes extremely light.

The light-emitting diode lighting device of the present invention includes a rectified DC power supply; a power factor correction circuit mainly composed of a boost chopper and having an input terminal connected to the rectified DC power supply; an input terminal connected to an output terminal of the power factor correction circuit A connected DC converter; a light emitting diode connected to the output terminal of the DC converter for lighting; a dimming signal output means; a DC converter and a power factor correction circuit according to the dimming signal output from the dimming signal output means Controls at least one of the outputs, and also has a dimming characteristic in which the light output of the light emitting diode continuously changes, and the power factor improves as the dimming degree increases until the light output of the light emitting diode drops to a predetermined level configured as output voltage of the circuit is gradually reduced and the light output of the light emitting diode to stop the operation of the power factor correction circuit when lowered to a predetermined level rectified direct current It is characterized in that it comprises a; output control means for controlling so as to be supplied directly to DC converter.

  The present invention allows the following aspects.

  The rectified DC power supply supplies power for rectifying the AC voltage of an AC power supply, for example, a commercial AC power supply, to turn on the light emitting diode to a power factor correction circuit and a DC converter, which will be described later, in a DC mode. The mode of rectification is not particularly limited, but full wave rectification is preferable.

  Further, the DC power supply may have a smoothed DC output voltage. However, since the subsequent power factor correction circuit includes the smoothing means, a configuration that outputs a non-smooth DC voltage obtained by rectifying the AC voltage may be used.

  In the present invention, the power factor correction circuit is mainly composed of a step-up chopper, and improves the power factor of the AC current supplied from the AC power source to a desired level. In the step-up chopper, a smoothing capacitor disposed at the output end is obtained by charging the inductor when the high-frequency switching of the switching element is on and releasing the electromagnetic energy accumulated in the inductor during the off-operation. Since the circuit operation to be charged is performed, the input current proportional to the rectified DC power supply voltage waveform flows in synchronism, so that the power factor is improved while performing the boosting operation.

  In addition, the power factor correction circuit can change its output voltage independently or in cooperation with a DC converter described later according to a dimming signal described later.

  Further, the step-up chopper is allowed to have a general circuit configuration including a circuit configuration in which an inductor and a switching element are connected in series, and a series circuit of a flywheel diode and a smoothing capacitor is connected in parallel with the switching element. The switching element to be used is not particularly limited, and may be either a current control type switching element or a voltage control type switching element. However, a gate voltage control type voltage control type switching element such as an FET (field effect transistor) or IGBT is particularly preferable because the conversion efficiency is increased.

  Furthermore, when the switching element of the boost chopper is maintained in the OFF state, the power factor correction circuit stops the boost operation and the smoothing capacitor is directly charged by the output voltage of the smoothing DC power source via the inductor. Therefore, a voltage equal to the output voltage of the smoothing DC power supply is output.

  The DC converter is a circuit means for obtaining a desired output voltage suitable for a load by converting the boosted DC output voltage of the power factor correction circuit. Further, the light-emitting diode can be dimmed and lit by changing the output voltage of the DC converter in accordance with a dimming signal described later.

  Further, the specific circuit system of the DC converter is not particularly limited in the present invention. For example, a switching converter such as a step-down chopper, a reverse polarity converter, or a flyback converter can be appropriately selected and employed. Note that the switching element of the DC converter can be appropriately selected for the same reason as in the step-up chopper.

  The light emitting diode is connected to the output terminal of the DC converter as a load, and is lit by being energized by the output current. Since the number of light emitting diodes connected to the output terminal of the DC converter is not particularly limited, it may be one or more. In addition, since the light emitting characteristics, package mode, and the like of the light emitting diode are not particularly limited, various known light emitting characteristics, package modes, ratings, and the like can be appropriately selected and used.

  The dimming signal output means is means for generating and outputting a dimming signal. And the arrangement | positioning position is not specifically limited. In other words, it may be mounted on a position close to the main part of the light-emitting diode lighting device including the power factor correction circuit and the DC converter, for example, on the same wiring board as the main part. Further, it may be arranged at a position separated from the main part.

  Further, the dimming signal output means is not particularly limited in the form of the dimming signal to be output. For example, a duty signal whose pulse duty changes according to the dimming degree, a digital signal obtained by digitizing the dimming degree, a variable voltage signal whose voltage value changes according to the dimming degree, and the like can be selectively employed as appropriate.

  The control means controls the output of at least one of the DC converter and the power factor correction circuit according to the dimming signal output from the dimming signal output means, and performs a dimming control operation for dimming the light emitting diode. . In addition, when the light output of the light emitting diode drops to a predetermined level, the power factor correction circuit controls the output of the rectified DC power supply to be directly supplied to the DC converter by stopping the operation of the power factor correction circuit. The protective action is performed.

The output control for at least one of the DC converter and the power factor correction circuit for the dimming control operation is based on a predetermined dimming characteristic set in the control means and a correlation of the dimming signal output from the dimming signal output means. Done. The dimming characteristics can be set in advance so that the light amount and the dimming degree of the light emitting diode continuously change . For example, the light amount and dimming degree of the light emitting diode may change continuously and linearly, or the light amount and dimming degree of the light emitting diode may change continuously and non-linearly .

  For the protection operation of the power factor correction circuit, the control means stops the operation of the power factor correction circuit when the light output of the light emitting diode drops to a predetermined level. Then, a DC voltage is applied to the input end of the DC converter without performing a power factor correction operation. The predetermined level of the light output of the light emitting diode can be an appropriate level such as a value selected from a range of 40% or less, for example, with respect to the light output during non-dimming, that is, all light. In addition, the level can be set to be fixed or variable.

  In addition, instead of directly detecting the light output of the light emitting diode, the control means detects the light output of the light emitting diode indirectly by electrically detecting the state of the light emitting diode lighting circuit described above. The power factor correction circuit can be configured to perform a protection operation. That is, the control means constantly monitors the output voltage, output current, or output power of the DC converter, and when the electric signal becomes a value corresponding to when the light output of the light emitting diode falls to a predetermined level, The operation of the rate improvement circuit can be stopped. Alternatively, as another configuration, the dimming signal can be monitored, and when the dimming degree reaches a predetermined value, this can be detected to operate the power factor correction circuit.

Further, the control means, the output voltage of the power factor correction circuit to the light output of the light emitting diode is reduced to a predetermined level, the dimming degree is increased (light output is lowered) configured to go low Hesi accordance . In an embodiment of this may be reduced, the output voltage of the power factor correction circuit over the entire dimming range, since the dimming degree is large to some extent (the light output drops to some extent) to the stop of the operation of the power factor correction circuit The output voltage of the power factor correction circuit can be reduced only during the period.

According to the present invention, when the light output of the light emitting diode falls below a predetermined level due to dimming, the power factor correction circuit mainly composed of the boost chopper stops operating, and the power factor correction action is not performed. Since the DC voltage is input to the DC converter, when the load becomes very light due to deep dimming, the boost chopper of the power factor correction circuit does not operate intermittently, so there is no flickering in the lighting of the light emitting diode, When the power factor correction action is not performed, the load is light and the effect is small . In addition, the dimming degree increases (the light output decreases) until the light output of the light emitting diode decreases to a predetermined level. As the output voltage of the improvement circuit decreases, the output voltage of the power factor improvement circuit does not change suddenly before and after the power factor improvement operation stops. Together it is stabilized, it is possible to provide a light emitting diode lighting apparatus capable of smooth dimming.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments and a reference example for carrying out the present invention will be described with reference to the drawings.

1 to 3 show a first embodiment of the present invention, FIG. 1 is a circuit diagram of light emitting diode lighting apparatus, FIG. 2 is dimming signal waveform diagram, except 3 dimming characteristics and power factor correction circuit It is a graph as a reference example which shows the relationship of output voltage.

  In this embodiment, the light-emitting diode lighting device includes a rectified DC power supply RDC, a power factor correction circuit PFI, a DC converter DCC, a light-emitting diode LED, a dimming signal output means DSG, and a control means CC. Power is supplied from an AC power supply AC.

  The rectified DC power supply RDC is composed of a bridge-type full-wave rectifier circuit Rec whose AC input terminal is connected to the commercial AC power supply AC, and outputs a non-smooth DC voltage.

  The power factor correction circuit PFI is mainly composed of a boost chopper. That is, a series circuit of an inductor L1 and a switching element Q1 connected to the DC output terminal of the rectified DC power supply RDC, a series circuit of a flywheel diode D1 and a smoothing capacitor C1 connected in parallel to the switching element Q1, and an output voltage detection circuit VD The power factor improving operation is performed by the control of the control means CC described later. The switching element Q1 is made of a MOSFET. The output voltage detection circuit VD takes out the divided output voltage from a voltage dividing circuit connected in parallel to the smoothing capacitor C1, and inputs it to the control means CC described later. The voltage dividing circuit is constituted by a series circuit of resistors R1 and R2, and a terminal voltage of the resistor R2 is output.

  The DC converter DCC is mainly composed of a step-down chopper. That is, a series circuit of a switching element Q2 and a flywheel diode D2 connected between both ends of a smoothing capacitor C1, which is an output terminal of the power factor correction circuit PFI, and a series circuit of an inductor L2 and a smoothing capacitor C2 connected in parallel to the flywheel diode D2. And a load current detection circuit ID, and performs a DC voltage conversion operation under the control of the control means CC described later. The load current detection circuit ID is composed of a resistor R3 inserted in series with a light emitting diode LED described later. The switching element Q2 is made of a MOSFET.

  A plurality of light emitting diodes LED are connected in series, and are connected to both ends of a smoothing capacitor C2 that is an output end of the DC converter DCC via a load current detection circuit ID.

  The dimming signal output means DSG outputs a dimming signal for dimming and lighting the light emitting diode LED, and inputs the dimming signal to the control means CC described later. In the present embodiment, the dimming signal is composed of a voltage pulse train whose duty changes according to the dimming ratio as shown in the waveform of FIG. In the figure, symbol T represents a pulse period, and t represents a pulse duty. The duty ratio: (t / T) × 100% is the setting signal for dimming lighting.

  The control means CC can be composed mainly of a microcomputer, and functionally includes a power factor correction control unit CPF, an operation control unit CPA, and a DC converter control unit CDC. The power factor improvement control unit CPF can be configured in combination with a boost chopper by a microcomputer different from the operation control unit CPA and the DC converter control unit CDC. However, the power factor improvement control unit CPF is connected to the switching element Q1 of the power factor improvement circuit PFI including the boost chopper. A drive signal composed of a pulse voltage is supplied. Also, feedback control is performed so that the output voltage controlled and input from the output voltage detection circuit VD of the boost chopper becomes a predetermined value, thereby controlling the duty of the drive signal to a predetermined value.

  In this embodiment, the operation control unit CPA monitors the dimming signal output from the dimming signal output means DSG, and the duty, and thus the light output of the corresponding light emitting diode, decreases to a predetermined level. When the predetermined value, which is the value at the time of reaching, is reached, the power factor correction control unit CPF is controlled to stop the supply of the drive signal for the boost chopper. As a result, the switching element Q1 of the step-up chopper is maintained in the OFF state, so that the power factor correction circuit PFI stops its operation, so that the smoothing capacitor C1 is charged with the non-smooth DC voltage supplied from the rectified DC power supply RDC. Is done.

  The DC converter control unit CDC supplies a drive signal composed of a pulse voltage to the switching element Q2 of the step-down chopper. Further, feedback control is performed so that the load current controlled and input from the load current detection circuit ID of the DC converter DCC is constant, and the drive signal is PWM-controlled according to the dimming signal.

Next, the circuit operation of the light emitting diode lighting device of this embodiment will be described. That is, by operating the boost chopper of the power factor correction circuit PFI, the power factor of the light emitting diode lighting device is improved and boosted to be higher than the voltage of the commercial AC power supply AC, and obtained from the output voltage detection circuit VD. A DC voltage feedback-controlled using the feedback voltage is output from the power factor correction circuit PFI.

  The output voltage of the power factor correction circuit PFI is applied to the input terminal of the DC converter DCC. As a result, the DC converter DCC performs a step-down operation, so that a DC voltage adjusted to a required value appears at the output terminal of the light emitting diode LED of the load. As a result, a load current flows through the light emitting diode LED connected to the output terminal as a load of the DC converter DCC, so that the light emitting diode LED is turned on. The lighting at this time is performed under constant current control by the cooperation of the load current detection circuit ID of the DC converter DCC and the control means CC.

  Further, when the dimming signal sent from the dimming signal output means DSG is control-inputted to the DC converter control unit CDC, the DC converter control unit CDC generates a PWM-controlled drive signal corresponding to the dimming signal to generate the DC converter. This is supplied to the DCC switching element Q2. As a result, since the reference value for constant current control of the load current is changed according to the dimming signal, the light emitting diode LED performs dimming lighting of the light output corresponding to the dimming signal.

  On the other hand, the operation control unit CPA of the control means CC monitors the dimming signal, and when the dimming signal exceeds a preset duty, supply of a drive signal to the switching element Q1 by the power factor correction control unit CPF. To stop. For this reason, it is possible to avoid intermittent oscillation of the power factor correction circuit PFI when the light output of the light emitting diode LED becomes small and the load becomes light.

The dimming characteristics as a reference example in the first embodiment of the present invention are set so that the light output gradually decreases by about 20%, for example, as shown in FIG. When the optical output exceeds about 40%, the control by the operation control unit CPA is activated and the power factor correction operation is stopped, so that the boosting action is eliminated, and the output voltage of the power factor correction circuit PFI is rectified without boosting. It becomes equal to the output voltage of the DC power supply RDC and decreases.

  FIG. 4 is a graph showing the relationship between the dimming characteristics and the output voltage of the power factor correction circuit in the second embodiment for implementing the light emitting diode lighting device of the present invention.

  In this embodiment, the dimming characteristics change linearly continuously from 100% to 0%. In the power factor correction circuit PFI, the pressure increasing action is kept constant until the optical output decreases from 100% to about 75%. The output of the rectified DC power supply RDC with no output voltage when the optical output exceeds about 40% and the control by the protection operation control unit CPA is activated as the optical output further decreases linearly. Equal to the voltage.

  Thus, according to the second embodiment, since the output voltage of the power factor correction circuit PFI does not change suddenly before and after the power factor correction operation is stopped, the control of the DC converter DCC is stabilized and smooth dimming is performed. It can be performed. Therefore, this embodiment is suitable for setting continuous light control characteristics.

1 is a circuit diagram of a light-emitting diode lighting device according to a first embodiment of the present invention. Similarly dimming signal waveform diagram Similarly , a graph as a reference example showing the dimming characteristics and output voltage of the power factor correction circuit The graph which shows the output voltage of the light control characteristic and power factor improvement circuit in 2nd Embodiment for implementing the light emitting diode lighting device of this invention

Explanation of symbols

  CC: control means, CDC: DC converter control section, CPA: operation control section, CPF: power factor correction control section, DCC: DC converter, DSG: dimming signal output means, ID: load current detection circuit, LED: light emitting diode , PFI: Power factor correction circuit, RDC: Rectified DC power supply, VD: Output voltage detection circuit

Claims (1)

  1. A rectified DC power supply;
    A power factor correction circuit composed mainly of a step-up chopper and having an input terminal connected to a rectified DC power supply;
    A DC converter whose input is connected to the output of the power factor correction circuit;
    A light-emitting diode that is lit and connected to the output end of the DC converter;
    Dimming signal output means;
    Controlling the output of at least one of the DC converter and the power factor correction circuit according to the dimming signal output from the dimming signal output means , and having a dimming characteristic in which the light output of the light emitting diode continuously changes, It is configured so that the output voltage of the power factor correction circuit decreases as the dimming degree increases until the light output of the light emitting diode decreases to a predetermined level, and when the light output of the light emitting diode decreases to a predetermined level. Control means for stopping the operation of the power factor correction circuit and controlling the output of the rectified DC power supply to be directly supplied to the DC converter;
    A light-emitting diode lighting device comprising:
JP2008203609A 2008-08-06 2008-08-06 Light emitting diode lighting device Expired - Fee Related JP5263503B2 (en)

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JP5592667B2 (en) * 2010-02-22 2014-09-17 パナソニック株式会社 LED lighting circuit
JP5442505B2 (en) * 2010-03-24 2014-03-12 パナソニック株式会社 Power supply unit and lighting apparatus using the same
JP5707564B2 (en) * 2010-07-29 2015-04-30 パナソニックIpマネジメント株式会社 LED lighting device, lighting fixture including LED lighting device, and lighting system including LED lighting device
JP2012049273A (en) * 2010-08-26 2012-03-08 Toshiba Lighting & Technology Corp Dc power supply device and led lamp system
JP5425124B2 (en) * 2011-02-24 2014-02-26 三菱電機株式会社 Power supply device and lighting device
JP5738032B2 (en) * 2011-03-28 2015-06-17 三菱電機株式会社 LED lighting device
KR101216677B1 (en) 2011-04-14 2012-12-28 서영석 A Controller of AC-DC Converter for LED lighting
GB2492833A (en) * 2011-07-14 2013-01-16 Softkinetic Sensors Nv LED boost converter driver circuit for Time Of Flight light sources
JP5958851B2 (en) * 2011-11-24 2016-08-02 パナソニックIpマネジメント株式会社 LED driving device and lighting device using the same
JP5930769B2 (en) * 2012-02-29 2016-06-08 新日本無線株式会社 Load drive circuit
JP5942256B2 (en) 2012-06-08 2016-06-29 パナソニックIpマネジメント株式会社 Lighting device and lighting apparatus
JP2014002867A (en) 2012-06-15 2014-01-09 Panasonic Corp Lighting device and illuminating fixture
JP5999326B2 (en) 2012-07-05 2016-09-28 パナソニックIpマネジメント株式会社 LED lighting device and lighting apparatus
WO2015011865A1 (en) * 2013-07-25 2015-01-29 パナソニックIpマネジメント株式会社 Semiconductor light source drive device
KR20170077518A (en) * 2015-12-28 2017-07-06 엘지이노텍 주식회사 LED voltage driver circuit

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JP2001351789A (en) * 2000-06-02 2001-12-21 Toshiba Lighting & Technology Corp Drive device for light-emitting diode
JP3741035B2 (en) * 2001-11-29 2006-02-01 サンケン電気株式会社 Switching power supply

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