JP2014072146A - Lighting device and luminaire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress flickering of a light source when power-up, without deteriorating power factor while lighting the light source.SOLUTION: A DC-DC conversion unit 22 of an LED lighting device 12 outputs a DC power by performing improvement of power factor of DC power and adjustment of voltage by switching operation. A control unit 24 of the LED lighting device 12 compares the voltage of DC power output from the DC-DC conversion unit 22 with a predetermined voltage every first period before an LED 11 is lighted by receiving DC power supply, and every second period longer than the first period after the LED 11 is lighted, and controls the switching operation of the DC-DC conversion unit 22 on the basis of the comparison results.

Description

  The present invention relates to a lighting device and a lighting device. The present invention particularly relates to an LED lighting device.

  There is an LED lighting device using a power factor improving converter (for example, see Patent Document 1).

JP 2010-40400 A

  In an LED lighting device using a power factor improving type converter, in order to improve the power factor (that is, to suppress high-frequency current), the response to load fluctuations must be lowered. Since the output voltage of the power factor correction type converter drops momentarily due to the rush current, there is a problem that the LED flickers.

  Here, the responsiveness is the frequency (that is, the frequency) at which feedback is applied to the power factor improving converter. If the period for applying feedback is short, the output can be kept substantially constant even if the load fluctuates. On the other hand, if the period for applying feedback is long, as described above, there is a possibility that the output decreases due to a sudden increase in current at the time of starting the power supply and the LED flickers.

  An object of the present invention is to suppress flickering of a light source at the time of power activation without deteriorating the power factor when the light source is turned on, for example.

A lighting device according to one aspect of the present invention includes:
A DC power supply for supplying DC power;
A direct current direct current converter that outputs the direct current power by performing a switching operation to improve the power factor of the direct current power supplied from the direct current power supply unit and adjust the voltage; and
A lighting unit that is connected to an external light source and supplies the DC power output from the DC / DC conversion unit to the light source to light the light source;
The DC power voltage output from the DC / DC converter is set to a predetermined voltage every first cycle before the light source is turned on and every second cycle longer than the first cycle after the light source is turned on. And a control unit that controls the switching operation of the DC / DC conversion unit based on the comparison result.

  In one aspect of the present invention, the DC / DC conversion unit of the lighting device outputs the DC power by performing the switching operation to improve the power factor of the DC power and adjust the voltage. The controller of the lighting device outputs the DC light source from the DC / DC converter every first cycle before the light source is lit by receiving the supply of DC power and every second cycle longer than the first cycle after the light source is turned on. The voltage of the direct current power is compared with a predetermined voltage, and the switching operation of the direct current direct current converter is controlled based on the comparison result. For this reason, according to one aspect of the present invention, it is possible to suppress flickering of the light source at the time of power activation without deteriorating the power factor when the light source is turned on.

FIG. 3 is a circuit diagram illustrating a configuration of the lighting apparatus according to Embodiment 1; The graph which shows the relationship between the PFC output and LED current when Embodiment 1 is not applied. FIG. 6 is a circuit diagram illustrating a configuration of a lighting device according to Embodiment 2. FIG. 6 is a circuit diagram illustrating a configuration of a lighting device according to Embodiment 3.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of each embodiment, the directions such as “up”, “down”, “left”, “right”, “front”, “back”, “front”, “back” are However, it is not intended to limit the arrangement or orientation of devices, instruments, parts, or the like.

Embodiment 1 FIG.
FIG. 1 is a circuit diagram showing a configuration of lighting apparatus 10 according to the present embodiment.

  In FIG. 1, the illumination device 10 includes an LED 11 and an LED lighting device 12.

  The LED 11 includes, for example, one white LED or a plurality of white LEDs connected in series with each other. The LED 11 is an example of a light source, and may be replaced with another type of light source such as an organic EL.

  The LED lighting device 12 is an example of a lighting device, and includes a DC power supply unit 21, a DC / DC conversion unit 22, a lighting unit 23, and a control unit 24.

  The DC power supply unit 21 supplies DC power to the DC / DC conversion unit 22. In the present embodiment, the DC power supply unit 21 is configured as a rectifier circuit including a bridge rectifier 31 (diode bridge). The DC power supply unit 21 performs full-wave rectification on the AC power supplied from the commercial power supply 13 by the bridge rectifier 31, converts it into pulsating power (that is, DC power), and outputs it.

  The DC / DC conversion unit 22 performs switching operation to improve the power factor of the DC power supplied from the DC power supply unit 21 and adjust the voltage, and outputs the DC power to the lighting unit 23. In the present embodiment, the DC / DC converter 22 is configured as a boost converter including an inductor 41, a diode 42, a smoothing capacitor 43 (electrolytic capacitor), and a switching element 44 (MOSFET). The DC / DC converter 22 is configured so that the current waveform of the pulsating power supplied from the DC power supply unit 21 approximates the voltage waveform of the pulsating power (that is, the power factor of the pulsating power is 1). The switching elements 44 are alternately turned on and off. As described above, the DC / DC converter 22 improves the power factor of the pulsating power supplied from the DC power supply unit 21. Further, the DC / DC converter 22 accumulates energy in the inductor 41 by the current flowing from the DC power supply unit 21 when the switching element 44 is on. When the switching element 44 is off, the DC / DC converter 22 releases energy from the inductor 41, and a current generated by this energy flows to the smoothing capacitor 43 via the diode 42 to charge the smoothing capacitor 43. The DC / DC converter 22 outputs, from the smoothing capacitor 43, DC power having a voltage higher than the peak voltage of the pulsating power supplied from the DC power supply unit 21. As described above, the DC / DC converter 22 boosts and outputs the DC power supplied from the DC power supply unit 21.

  The lighting unit 23 is connected to the LED 11, and supplies the DC power output from the DC / DC conversion unit 22 to the LED 11 to light the LED 11. In the present embodiment, the lighting unit 23 is configured as a step-down converter (buck converter) including an inductor 51, a diode 52, a smoothing capacitor 53 (electrolytic capacitor), and a switching element 54 (MOSFET). When the switching element 54 is on, the lighting unit 23 causes the current flowing from the DC / DC conversion unit 22 to flow to the smoothing capacitor 53, charges the smoothing capacitor 53, and causes the inductor 51 to receive energy from the current flowing from the DC / DC conversion unit 22. Accumulate. When the switching element 54 is off, the lighting unit 23 releases energy from the inductor 51, and a current generated by this energy flows to the smoothing capacitor 53 through the diode 52 to charge the smoothing capacitor 53. Then, the lighting unit 23 outputs, from the smoothing capacitor 53, DC power having a voltage lower than the voltage of the DC power supplied from the DC / DC converter 22. In this way, the lighting unit 23 steps down the DC power supplied from the DC / DC converter 22 and outputs it.

  The control unit 24 determines the voltage of the DC power output from the DC / DC conversion unit 22 every predetermined period before the LED 11 is lit and every second period longer than the first period after the LED 11 is lit. And the switching operation of the DC / DC converter 22 is controlled based on the comparison result. In the present embodiment, the control unit 24 includes a feedback circuit 25, a boost converter control circuit 26, a phase correction circuit 27, a phase correction switching circuit 28, and a control IC 29 for controlling the step-down converter.

  The feedback circuit 25 divides the DC voltage output from the DC / DC converter 22 by the resistors 61 and 62, compares the divided voltage with the reference potential 64 by the comparator 63, and the output voltage of the DC / DC converter 22 is A voltage indicating whether the voltage is higher or lower than the required voltage (predetermined voltage) is output.

  The step-up converter control circuit 26 converts the current flowing through the source terminal of the switching element 44 of the DC / DC converter 22 into a voltage V 1 by the resistor 71 and inputs the voltage V 1 to the control IC 74. The boost converter control circuit 26 divides the pulsating voltage output from the bridge rectifier 31 of the DC power supply unit 21 by the resistors 72 and 73 and inputs the divided voltage V2 to the control IC 74. Further, the boost converter control circuit 26 inputs the voltage V3 output from the comparator 63 of the feedback circuit 25 to the control IC 74.

  The control IC 74 turns on / off the switching element 44 (that is, the switching element) so that the waveform of the voltage V1 (that is, the current flowing through the source terminal of the switching element 44) approximates the waveform of the voltage V2 (that is, the full-wave rectified waveform). The output voltage to the gate terminal 44). As a result, the power factor of the pulsating power from the DC power supply unit 21 is improved in the DC / DC conversion unit 22.

  The control IC 74 controls on / off of the switching element 44 (that is, the output voltage to the gate terminal of the switching element 44) according to the voltage V3. Specifically, if the voltage V3 is higher than the threshold value (that is, if the output voltage of the DC / DC converter 22 is higher than the required voltage), the control IC 74 determines the ratio of the period during which the switching element 44 is turned on (on duty). ). As a result, the DC voltage output from the DC / DC converter 22 drops. On the other hand, if the voltage V3 is lower than the threshold (that is, if the output voltage of the DC / DC converter 22 is lower than the required voltage), the control IC 74 decreases the on-duty of the switching element 44. As a result, the DC voltage output from the DC / DC converter 22 increases. By repeating this operation, the DC power conversion unit 22 boosts the pulsating power from the DC power supply unit 21.

  The phase correction circuit 27 corrects the frequency characteristics of the voltage V3 output from the feedback circuit 25 with the capacitor 81 and the resistor 82, thereby setting the responsiveness of the DC / DC converter 22 with respect to load fluctuations. That is, the period (first period) in which feedback is applied from the feedback circuit 25 to the boost converter control circuit 26 is determined by the time constant of the phase correction circuit 27 determined from the capacitance of the capacitor 81 and the resistance value of the resistor 82. In the present embodiment, as will be described later, by changing the time constant of the phase correction circuit 27, it is possible to switch the period for applying feedback.

  The phase correction switching circuit 28 divides the voltage Vo output from the lighting unit 23 to the LED 11 by the resistors 91 and 92 and detects the voltage Vo. The phase correction switching circuit 28 turns off the transistor 93 if the voltage Vo is less than the VF (forward voltage) of the LED 11, and turns on the transistor 93 if the voltage Vo is equal to or higher than the VF of the LED 11. When the transistor 93 is on, the resistor 82 of the phase correction circuit 27 and the resistor 94 connected in series to the transistor 93 are connected in parallel to the capacitor 81 of the phase correction circuit 27, so that the time constant of the phase correction circuit 27 (capacitor 81 and the combined resistance value of the resistors 82 and 94). As a result, the period (first period) in which feedback is fed from the feedback circuit 25 to the boost converter control circuit 26 is switched to a longer period (second period).

  As described above, in the present embodiment, when the control unit 24 detects the voltage of the DC power supplied from the lighting unit 23 and the detected voltage reaches the VF of the LED 11, the first cycle to the second cycle. Switch to.

  In the present embodiment, the first period (the time constant of the phase correction circuit 27 when the transistor 93 is off) is 5 milliseconds or less. That is, before the LED 11 is turned on, the phase correction circuit 27 corrects the frequency characteristic of the voltage V3 output from the feedback circuit 25 to 200 Hz or more. When the frequency is lower than 200 Hz, as shown in FIG. 2, when the output voltage (PFC output) of the DC / DC converter 22 decreases due to a rapid current increase at the time of power activation (for example, the VF of the LED 11 is 210V). If the PFC output drops to 200V, the LED 11 will disappear), and it takes time for the output voltage of the DC / DC converter 22 to recover after the next feedback is applied. There is a risk of flickering. On the other hand, if the frequency is 200 Hz or higher, even if the output voltage of the DC / DC converter 22 is lowered, the next feedback is immediately applied, so that flickering of the LED 11 that can be recognized by humans can be prevented. . The effect is considered to increase as the frequency increases. However, if the frequency exceeds 1 kHz (1000 Hz), the circuit may oscillate. Therefore, the frequency before the LED 11 is turned on is approximately 1 kHz (that is, the first period is less). About 1 millisecond).

  In the present embodiment, the second period (the time constant of the phase correction circuit 27 when the transistor 93 is on) is 10 milliseconds or more. That is, after the LED 11 is turned on, the phase correction circuit 27 corrects the frequency characteristic of the voltage V3 output from the feedback circuit 25 to 100 Hz or less. When the frequency is higher than 100 Hz, the high frequency current increases, so that the power factor when the LED 11 is turned on deteriorates. On the other hand, if the frequency is 100 Hz or less, the high frequency current can be suppressed to prevent the power factor from deteriorating. It is desirable that the frequency after the LED 11 is turned on is approximately the same as the frequency of the commercial power supply 13, that is, about 50 Hz or about 60 Hz (that is, the second period is about 17 milliseconds or about 20 milliseconds).

  The control IC 29 detects the current output from the lighting unit 23 to the LED 11 by the voltage V4 applied to the resistor 55, and the switching element 54 of the lighting unit 23 is turned on / off according to the voltage V4 (that is, to the gate terminal of the switching element 54). Output voltage). Specifically, the control IC 29 increases the on-duty of the switching element 54 if the voltage V4 is higher than the required voltage. Thereby, the DC voltage output from the lighting part 23 falls. On the other hand, if the voltage V4 is lower than the required voltage, the control IC 29 reduces the on-duty of the switching element 54. Thereby, the DC voltage output from the lighting part 23 rises. By repeating this operation, the DC power from the DC / DC converter 22 is stepped down in the lighting unit 23.

  In the present embodiment, the lighting unit 23 is configured as a buck converter. However, the lighting unit 23 may be configured as another type of step-down converter such as a flyback converter, or may be configured as a boost converter. May be.

  In the present embodiment, the lighting unit 23 adjusts the voltage of the DC power output from the DC / DC conversion unit 22 by the switching operation and supplies the DC power to the LED 11. The DC power output from the DC / DC converter 22 may be supplied to the LED 11 as it is. That is, the lighting unit 23 may directly connect the DC / DC conversion unit 22 and the LED 11.

  As described above, the LED lighting device 12 according to the present embodiment includes the power factor improving converter (DC-DC converter 22), the feedback circuit 25 that feeds back the output of the power factor improving converter, and the feedback circuit 25. And a phase correction circuit 27 connected to the LED 11, and changing the phase correction before and after the LED 11 is turned on to change the response of the power factor improving converter to the load fluctuation.

  In this way, by switching the responsiveness to the load fluctuation of the power factor improving converter before and after the LED 11 is turned on, adjusting the phase correction to give priority to the response until the LED 11 is turned on and to prioritize the power factor after the LED 11 is turned on, The flickering of the LED 11 at the time of power activation can be suppressed without deteriorating the power factor when the LED 11 is turned on.

Embodiment 2. FIG.
In the present embodiment, differences from the first embodiment will be mainly described.

  FIG. 3 is a circuit diagram showing a configuration of lighting apparatus 10 according to the present embodiment.

  3, the configuration other than the phase correction switching circuit 28 is the same as that of the first embodiment shown in FIG.

  When the voltage Vo becomes equal to or higher than the VF of the LED 11, the phase correction switching circuit 28 does not immediately turn on the transistor 93 but turns on the transistor 93 after a delay time determined by the capacitance of the capacitor 95 has elapsed.

  As described above, in the present embodiment, the control unit 24 detects the voltage of the DC power supplied from the lighting unit 23, and when a predetermined time elapses after the detection voltage reaches the VF of the LED 11, Switching from the first period to the second period is performed. Thereby, the timing of switching from responsive priority to power factor priority can be surely after the LED 11 is turned on.

  In addition, it is desirable to apply this Embodiment especially when connecting the direct current direct current | flow conversion part 22 and LED11 instead of the lighting part 23 being comprised as a buck converter.

Embodiment 3 FIG.
In the present embodiment, differences from the first embodiment will be mainly described.

  FIG. 4 is a circuit diagram showing a configuration of lighting apparatus 10 according to the present embodiment.

  In FIG. 4, the configuration other than the phase correction switching circuit 28 is the same as that of the first embodiment shown in FIG.

  Usually, the ON voltage (for example, 0.6 V) of the transistor 93 is considerably lower than the VF (for example, 200 V) of the LED 11. Therefore, the transistor 93 may be turned on by the ripple of the voltage Vo.

  In the present embodiment, a Zener diode 96 is connected between the connection point of the resistors 91 and 92 of the phase correction switching circuit 28 and the base terminal of the transistor 93. Accordingly, the on-voltage of the transistor 93 can be substantially increased, and a situation where the transistor 93 is turned on due to noise can be avoided.

  As mentioned above, although embodiment of this invention was described, you may implement in combination of 2 or more among these embodiment. Alternatively, one of these embodiments may be partially implemented. Alternatively, two or more of these embodiments may be partially combined. In addition, this invention is not limited to these embodiment, A various change is possible as needed.

  DESCRIPTION OF SYMBOLS 10 Illuminating device, 11 LED, 12 LED lighting device, 13 Commercial power supply, 21 DC power supply part, 22 DC-DC conversion part, 23 Lighting part, 24 Control part, 25 Feedback circuit, 26 Boost converter control circuit, 27 Phase correction circuit, 28 phase correction switching circuit, 29, 74 control IC, 31 bridge rectifier, 41, 51 inductor, 42, 52 diode, 43, 53 smoothing capacitor, 44, 54 switching element, 55, 61, 62, 71, 72, 73, 82, 91, 92, 94 Resistor, 63 Comparator, 64 Reference potential, 81, 95 Capacitor, 93 Transistor, 96 Zener diode.

Claims (7)

A DC power supply for supplying DC power;
A direct current direct current converter that outputs the direct current power by performing a switching operation to improve the power factor of the direct current power supplied from the direct current power supply unit and adjust the voltage; and
A lighting unit that is connected to an external light source and supplies the DC power output from the DC / DC conversion unit to the light source to light the light source;
The DC power voltage output from the DC / DC converter is set to a predetermined voltage every first cycle before the light source is turned on and every second cycle longer than the first cycle after the light source is turned on. And a controller that controls the switching operation of the DC / DC converter based on the comparison result.   The control unit detects a voltage of DC power supplied from the lighting unit, and when a predetermined time elapses after the detected voltage reaches a forward voltage of the light source, the control unit starts from the first period and performs the second operation. 2. The lighting device according to claim 1, wherein switching to a cycle is performed. The lighting unit performs adjustment of the voltage of the DC power output from the DC / DC conversion unit by a switching operation to supply the DC power to the light source,
The control unit detects a voltage of DC power supplied from the lighting unit, and performs switching from the first cycle to the second cycle when the detected voltage reaches a forward voltage of the light source. The lighting device according to claim 1.   4. The lighting device according to claim 1, wherein the first period is 5 milliseconds or less and the second period is 10 milliseconds or more.   The lighting device according to claim 4, wherein the first period is about 1 millisecond.   6. The lighting device according to claim 4, wherein the second period is about 17 milliseconds or about 20 milliseconds. A lighting device according to any one of claims 1 to 6;
An illumination device comprising: a light source connected to a lighting unit of the lighting device.

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