JP2019204710A - Led lighting device and lighting fixture - Google Patents

Abstract

To provide an LED lighting device that reduces color flickering that is likely to occur when illumination light is dark.SOLUTION: An LED lighting device 30 for lighting multiple LED loads 21 to 24 with different emission colors includes: a power supply circuit 31; a selector circuit 32 that is fed from the power supply circuit 31 with respect to a selected LED load by sequentially selecting one of the LED loads 21 to 24 in a cyclic manner; and a control circuit 33 that controls the selector circuit 32. The control circuit 33 controls the selector circuit 32 to shorten the length of a power feeding section in which power is fed from the power supply circuit 31 to each LED load as the dimming rate that indicates brightness decreases, and provide a pause section in which power is fed to no LED load between the feeding section of the selected LED load and the feeding section of an LED load to be selected next, and prevents the pause section from becoming longer even when the dimming rate decreases.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an LED lighting device and a lighting fixture for lighting a plurality of LED (Light Emitting Diode) loads having different emission colors.

  Patent Document 1 discloses a lighting device capable of dimming and toning by sequentially switching and lighting a plurality of LEDs having different emission colors, and adjusting the intensity and mixing ratio of each emission color.

JP 2004-311635 A

  However, according to the above prior art, there is a problem that color flickering may occur as the light becomes darker due to light control, for example. Here, color flicker means that when there is a fast-moving object such as a fan's wing under the illumination light, an individual emission color of the LED appears on the object and is perceived by humans. Say. If the color flicker is intense, it may cause discomfort or discomfort to the person.

  Then, an object of this invention is to provide the LED lighting device and lighting fixture which reduce the color flickering which is easy to occur when illumination light is dark by light control.

  In order to solve the above problems, an LED lighting device of the present invention is an LED lighting device that lights a plurality of LED loads having different emission colors, and a power supply circuit that supplies power to the plurality of LED loads; A selector circuit that feeds power to the selected LED load from the power supply circuit by sequentially selecting one LED load among the LED loads, and a control circuit that controls the selector circuit, The control circuit shortens the length of the power feeding section that feeds power from the power supply circuit to each LED load as the dimming rate indicating brightness decreases, and then selects the power feeding section of the selected LED load, and then selects Between the power supply section of the LED load is provided a pause section where no LED load is fed, so that the pause section does not become long even if the dimming rate is reduced And controls the selector circuit.

  According to the LED lighting device and the lighting fixture of the present invention, it is possible to reduce the color flicker that is likely to occur when the illumination light is dark due to dimming.

FIG. 1 is a block diagram illustrating a configuration example of a lighting fixture including the LED lighting device according to Embodiment 1. FIG. 2 is a diagram showing a current waveform of the lighting fixture having the LED lighting device according to Embodiment 1. FIG. FIG. 3 is a diagram illustrating a circuit configuration example of a lighting fixture including the LED lighting device according to Embodiment 1. 4A is a diagram showing a current waveform and a voltage waveform of each part of the lighting fixture having the LED lighting device according to Embodiment 1. FIG. FIG. 4B is a diagram showing another example of the current waveform and voltage waveform of each part of the lighting fixture having the LED lighting device according to Embodiment 1. FIG. 5 is a diagram illustrating a current waveform of a lighting fixture having the LED lighting device according to the second embodiment. FIG. 6 is a diagram illustrating a current waveform of a lighting fixture having the LED lighting device according to the third embodiment. FIG. 7A is a diagram illustrating an appearance example of a lighting fixture including the LED lighting device according to each embodiment. Drawing 7B is a figure showing other examples of appearance of lighting fixture which has a LED lighting device concerning each embodiment. FIG. 7C is a diagram showing still another external appearance example of the lighting fixture having the LED lighting device according to each embodiment. FIG. 8 is a diagram illustrating a configuration of a lighting fixture of a comparative example. FIG. 9 is a diagram illustrating a current waveform of the lighting fixture of the comparative example.

(Knowledge that became the basis of the present invention)
The present inventor has found that the following problems occur with respect to the lighting device described in the “Background Art” column.

  First, the lighting fixture which concerns on the knowledge of this inventor is demonstrated as a comparative example.

  FIG. 8 is a diagram illustrating a configuration of a lighting fixture of a comparative example according to the knowledge of the present inventor. The luminaire shown in the figure includes a power supply circuit 90, LED loads 91 to 94, and switching elements SW3 to SW6. The power supply circuit 90 includes switching elements SW1 and SW2 and an inductor L0, and is a so-called step-down chopper type DC-DC converter. The switching elements SW1 and SW2 are controlled so as to be exclusively turned on. The inductor L0 stores and discharges energy supplied from the connection point of the switching elements SW1 and SW2.

  The LED loads 91 to 94 have different emission colors.

  The switching elements SW3 to SW6 are controlled to turn on in order within one cycle.

  FIG. 9 is a diagram illustrating a current waveform of the lighting fixture of the comparative example. The vertical axis in the figure represents the inductor current. The inductor current is an output current of the power supply circuit 90 that is supplied to any of the LED loads via the inductor L0. The horizontal axis indicates time. The upper part of the figure shows a relatively bright state. The lower part of the figure shows a darkened state by dimming. Color α, color β, color γ, and color δ indicate the emission colors of the LED loads 91 to 94. The light emission colors of the LED loads 91 to 94 are, for example, red, green, blue, and white.

  As shown in FIG. 9, the LED loads 91 to 94 emit light in a cycle in the cycle Ts. This operation is called progressive lighting. FIG. 9 shows a case where the period Ts is fixed and the switching frequency of the switching elements SW3 to SW6 is fixed. When dimming in a state where the switching frequency is fixed, the on-time is shortened and the pause period Tx is lengthened. When the pause section Tx is long, there is a problem that color flicker may be perceived by the human eye during forward lighting.

  Color flickering separates individual emission colors when there is an object that moves quickly under illumination light, for example, when you shake your hand quickly under illumination light, or when the fan blades are rotating. This phenomenon is visible. As the flickering period Tx is longer, the color flickering becomes easier to see on the object that moves quickly. Such a color flicker may give a person an uncomfortable feeling or an uncomfortable feeling.

  In order to solve such a problem, an LED lighting device according to an aspect of the present invention is an LED lighting device that lights a plurality of LED loads having different emission colors, and supplies power to the plurality of LED loads. And a selector circuit for feeding power from the power supply circuit to the selected LED load by sequentially selecting one LED load among the plurality of LED loads in order, and controlling the selector circuit A control circuit, and the control circuit shortens the length of the power feeding section that feeds power from the power supply circuit to each LED load as the dimming rate indicating brightness decreases, and Between the power supply section and the power supply section of the LED load to be selected next, there is provided a stop section where no LED load is supplied with power, and the stop section is long even if the dimming rate decreases. Not without controlling the selector circuit so.

  As a result, even if the dimming rate decreases, that is, even if the illumination light becomes dark due to dimming, the length of the resting period does not increase, so that it is manifested that the emission colors appear to be separated on a rapidly moving object. That is, color flicker can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  Note that each of the embodiments described below shows one comprehensive or specific example of the present invention. The numerical values, shapes, materials, constituent elements, arrangement positions and connecting forms of the constituent elements, steps, order of steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept are described as optional constituent elements.

(Embodiment 1)
[1.1 Configuration of LED lighting device and lighting fixture]
First, the structural example of the lighting fixture 100 provided with the LED lighting device 30 which concerns on Embodiment 1 is demonstrated.

  FIG. 1 is a block diagram illustrating a configuration example of a lighting fixture 100 including the LED lighting device 30 according to the first embodiment. The luminaire 100 shown in FIG. 1 includes an AC-DC power supply 10, a light source 20, and an LED lighting device 30.

  The AC-DC power supply 10 is connected to, for example, a commercial 100V power supply, and receives AC power and converts it into DC power.

  The light source 20 includes LED loads 21 to 24. The LED loads 21 to 24 have different emission colors. The emission colors of the LED loads 21 to 24 are, for example, R (red), G (green), B (blue), and W (white).

  The LED lighting device 30 is a device that lights a plurality of LED loads 21 to 24 having different emission colors. Therefore, the LED lighting device 30 includes a power supply circuit 31, a selector circuit 32, and a control circuit 33.

  The power supply circuit 31 is a DC-DC converter that converts DC power from the AC-DC power supply 10 into DC power having a different voltage and supplies the converted DC power to the light source 20.

  The selector circuit 32 feeds power to the selected LED load from the power supply circuit 31 by sequentially selecting one LED load from the plurality of LED loads 21 to 24 sequentially. Therefore, the selector circuit 32 includes switching elements M3 to M6. Each of the switching elements M3 to M6 is connected in series with any one of the LED loads 21 to 24. For example, in FIG. 1, the switching element M3 is connected to the LED load 21 in series. The switching element M4 is connected to the LED load 22 in series. The switching element M5 is connected to the LED load 23 in series. The switching element M6 is connected to the LED load 24 in series. These switching elements M3 to M6 are controlled to be exclusively turned on, for example. Thereby, the LED loads 21 to 24 emit light exclusively, that is, one by one.

  The control circuit 33 controls the selector circuit 32 so as to sequentially select one LED load from the plurality of LED loads 21 to 24 sequentially. Specifically, the control circuit 33 shortens the length of the power feeding section in which power is fed from the power supply circuit 31 to each LED load as the dimming rate indicating brightness is smaller. In addition, the control circuit 33 provides a pause section in which no LED load is fed between the power supply section of the selected LED load and the power supply section of the next selected LED load, and the dimming rate is reduced. However, the selector circuit 32 is controlled so that the pause period does not become longer. At this time, the cycle lighting cycle, which is a cycle in which the plurality of LED loads 21 to 24 are selected in a cycle, becomes shorter as the dimming rate is smaller, that is, as the illumination light is darkened.

  FIG. 2 is a diagram illustrating an example of a current waveform of the lighting fixture 100 including the LED lighting device 30 according to the first embodiment. In FIG. 2, it is assumed that the power supply circuit 31 is a switching power supply including an inductor and supplies power to the LED loads 21 to 24 via the inductor. In the upper and lower stages of the figure, the vertical axis indicates the inductor current, that is, the current supplied from the power supply circuit 31 to any one of the LED loads. The horizontal axis indicates time. The upper part of the figure shows the waveform of the inductor current when the dimming rate is the first value. The lower part of the figure shows the waveform of the inductor current when the dimming rate is a second value smaller than the first value.

  In FIG. 2, sections TS <b> 1 and TS <b> 2 indicate a one-round lighting cycle that is a cycle in which the LED loads 21 to 24 are turned on once. Here, the round-trip lighting periods TS1 and TS2 change according to the dimming rate. The colors α, β, γ, and δ indicate the emission colors of the LED loads 21 to 24, and are, for example, R (red), G (green), B (blue), and W (white).

  A section Ta is a power feeding section in which power is supplied from the power supply circuit 31 to the LED load 21 of the emission color α. Similarly, sections Tb, Tc, and Td are power supply sections in which power is supplied from the power supply circuit 31 to the LED loads 22, 23, and 24.

  The section Tx is a rest section where no power is supplied to any LED load.

  As shown in the figure, when the dimming rate changes as shown in the upper and lower stages, the length of the feeding section also changes. That is, when the dimming rate is reduced, the power supply section is shortened, and the power supply amount is reduced and darkened. The amount of power supply corresponds to a triangular area in FIG. In FIG. 2, the length of the pause section Tx is controlled so as not to increase even when the dimming rate changes. Thereby, in FIG. 2, the color flicker can be reduced as compared with the comparative example shown in FIG. 9.

  Next, a more specific circuit example of the lighting fixture 100 having the LED lighting device will be described.

  FIG. 3 is a diagram illustrating a circuit configuration example of the lighting fixture 100 including the LED lighting device 30 according to the first embodiment. As illustrated in FIG. 3, the lighting fixture 100 includes a light source 20 and an LED lighting device 30. However, in FIG. 3, the AC-DC power supply 10 shown in FIG. 1 is omitted.

  The LED load 21 in the light source 20 is connected in series with the switching element M3, and lighting is controlled by turning on and off the switching element M3. The longer the on-time of the switching element M3, the more current flows and the amount of light emission increases. Become.

  As a specific circuit example, the LED load 21 of FIG. 3 is connected in series with LEDs d1 to d3, a smoothing capacitor C2 connected in parallel with the LEDs d1 to d3, and a parallel circuit including the LEDs d1 to d3 and the smoothing capacitor C2. And a back-flow preventing diode Da and a discharging resistor R2 when the power is off.

  The LEDs d1 to d3 are LED light emitting elements of the same emission color connected in series, and are connected in series with the switching element M3.

  The smoothing capacitor C2 smoothes the inductor current supplied from the inductor L1 via the diode Da.

  The diode Da prevents a current from flowing backward from the smoothing capacitor C2 to the inductor L1. That is, the diode Da supplies the charges charged in the smoothing capacitor C2 only to the LEDs d1 to d3.

  The resistor R2 has a high resistance value, and discharges the electric charge of the smoothing capacitor C2 after the power supply is turned on.

  The LED loads 22 to 24 have a configuration similar to the LED load 21 except that the emission colors are different. The LED load 21 may be configured without the smoothing capacitor C2 and the backflow prevention diode Da. The LED loads 22 to 24 are the same.

  The power supply circuit 31 in the LED lighting device 30 shows an example of a step-down chopper circuit in FIG. Specifically, the power supply circuit 31 includes a regulator 34, an HVIC (High Voltage Integrated Circuit) 35, input resistors R6 and R7, switching elements M1 and M2, and an inductor L1.

  The regulator 34 receives DC power from the AC-DC power supply 10 and supplies a stabilized power supply voltage to the HVIC 35 and the control circuit 33.

  The HVIC 35 supplies a gate signal to the switching elements M1 and M2 via the input resistors R6 and R7 under the control of the control circuit 33. The gate signals of the switching elements M1 and M2 are exclusively activated at high speed and periodically.

  The switching elements M1 and M2 are a high-side transistor and a low-side transistor for alternately connecting a DC voltage supplied from the AC-DC power supply 10 and a ground level to the inductor L1.

  The inductor L1 stores and discharges energy according to switching of the switching elements M1 and M2.

  The selector circuit 32 includes input resistors R8 to R11 and switching elements M3 to M6.

  The switching element M3 is connected in series with the LED load 21. A gate signal that instructs on and off is input from the control circuit 33 to the gate of the switching element M3 via the input resistor R8. The switching element M3 is turned on and off according to the gate signal.

  The switching elements M4 to M6 are the same as the switching element M3.

  The control circuit 33 may be configured by an MCU (Micro Controller Unit or Micro Computer Unit) that includes a processor, a memory, and a timer 36. The timer 36 measures various periodic times. For example, it is used for measuring a cycle in which the selection of the plurality of LED loads 21 to 24 completes, a power feeding section, a resting section, and the like.

[1.2 Operation of LED lighting device and lighting fixture]
Next, an operation example of the lighting fixture 100 including the LED lighting device 30 according to Embodiment 1 will be described.

  4A is a diagram showing a current waveform and a voltage waveform of each part of the lighting fixture having the LED lighting device according to Embodiment 1. FIG. The horizontal axis in the figure is the time axis. The vertical axis indicates the current or voltage of each part. The left side of the figure shows a waveform when the cycle lighting cycle is TS1, and corresponds to the upper part of FIG. The right side of FIG. 4A shows a waveform when the cycle lighting period is TS2, and corresponds to the lower part of FIG. That is, the right side of FIG. 4A shows a waveform when it is darker than the left side.

  The inductor current IL indicates a current flowing through the inductor L1, that is, a current supplied from the power supply circuit 31 to any LED load. In the figure, the section in which the inductor current IL flows is a power feeding section. The power supply section Ta indicates a section in which power is supplied from the power supply circuit 31 to the LED load 21. Similarly, power supply sections Tb to Td indicate sections where power is supplied from the power supply circuit 31 to the LED loads 22 to 24, respectively. The emission colors of the LED loads 21 to 24 are R, G, B, and W.

  The gate voltage V0 indicates a voltage input from the control circuit 33 to the gate of the switching element M1 via the HVIC 35. When the gate voltage V0 is at a high level, the switching element M1 is turned on. In the section where the gate voltage V0 is at a high level, the inductor current IL increases. At this time, the inductor L1 stores electric energy as magnetic energy. When the gate voltage V0 is at a low level, the switching element M1 is turned off. Immediately after the switching element M1 switches from the on state to the off state, the inductor L1 releases the stored energy, that is, the inductor current IL is supplied to the LED load while decreasing to 0 due to the counter electromotive force of the inductor L1. As a result, the feeding section Ta is longer than the high level section of the gate voltage V0. The inductor current IL is a triangular wave in the figure. The power feeding section in which power is supplied from the power supply circuit 31 to the LED load is equal to one triangular wave section.

  The gate voltage Vr indicates a voltage input from the control circuit 33 to the gate of the switching element M3. When the gate voltage Vr is at a high level, the switching element M3 is turned on, that is, the corresponding LED load 21 is selected. Further, the high level section of the gate voltage Vr is controlled to include a high level section of the gate voltage V0 and a period including a triangular wave of the corresponding inductor current IL. The gate voltages Vg, Vb, and Vw are the same as the gate voltage Vr. Note that a dead time during which all four gate voltages Vr, Vg, Vb, and Vw are at a low level is provided between high level intervals.

  The LED current Ir indicates a current flowing through the LEDs d1 to d3 in the LED load 21. After the power feeding section Ta, that is, after the power feeding from the power supply circuit 31 to the LED load 21 is finished, the LED current Ir does not become zero but continues to flow while the current decreases. This is due to the smoothing capacitor C2 and the backflow prevention diode Da.

  The LED currents Ig, Ib, and Iw are the same as the LED current Ir.

  As shown in FIG. 4A, the shorter the pulse width of the gate voltage V0, the shorter the power feeding section. The illumination light in the left round lighting cycle TS1 in FIG. 4A is brighter than the illumination light in the right round lighting cycle TS2. Dimming for adjusting the brightness of the illumination light in the lighting fixture 100 is realized by changing the brightness while maintaining the brightness ratio of the plurality of light emission colors constant. For example, in FIG. 4A, the control circuit 33 increases or decreases the four pulse widths of the gate voltage V0 while keeping the ratio of the four pulse widths of the gate voltage V0 in the power feeding sections Ta, Tb, Tc, and Tw constant. Light control. Further, the toning for adjusting the color of the illumination light in the luminaire 100 is realized by changing the ratio of the brightness of the plurality of emission colors. For example, in FIG. 4A, the control circuit 33 performs toning by changing the ratio of the four pulse widths of the gate voltage V0 in the power feeding sections Ta, Tb, Tc, and Tw.

  The control circuit 33 controls the selector circuit 32 so that the pause period Tx does not become longer even if the dimming rate is reduced. That is, the rest period Tx in the right round lighting cycle TS2 in FIG. 4A is controlled so as not to be longer than the pause section Tx in the left round lighting period TS1. In FIG. 4A, the rest period Tx in the right round lighting cycle TS2 has the same length as the pause section Tx in the left round lighting period TS1.

  Specifically, since the end point of the power feeding period is the time when the inductor current IL decreases to zero, the control circuit 33 detects that the inductor current IL decreases to zero level. The control circuit 33 provides a pause section Tx when the 0 level is detected. In the idle period Tx, all gate voltages are maintained at a non-active low level. The length of the pause period Tx can be easily set by, for example, a monostable multivibrator, a timer, or a counter. The control circuit 33 starts power supply to the next LED load in one-turn lighting at the end of the rest period Tx, that is, activates the gate voltage of the switching element corresponding to the next LED load.

  Further, when comparing the left side and the right side in FIG. 4A, the one-turn lighting cycle TS2 is shorter than the one-turn lighting cycle TS1 by the amount of each power feeding section Ta to Td being shorter.

  In FIG. 4A, even when it becomes dark due to dimming, the pause section does not become long, so that the color flicker can be reduced.

  The gate voltages Vr, Vg, Vb, and Vw may be as shown in FIG. 4B instead of FIG. 4A. FIG. 4B is a diagram illustrating another example of the current waveform and the voltage waveform of each part of the lighting fixture 100 having the LED lighting device 30 according to Embodiment 1. In the example of FIG. 4B, the high level sections of the gate voltages Vr, Vg, Vb, and Vw have substantially the same width as the corresponding one triangular wave. As a result, the dead times of the gate voltages Vr, Vg, Vb, Vw are wider than in FIG. 4A.

  In the example shown in FIGS. 4A and 4B, the switching element M <b> 1 of the power supply circuit 31 is controlled to be turned on within a period in which any LED load is selected by the selector circuit 32. That is, the switching operation in the power supply circuit 31 that is a switching power supply and the selection operation in the selector circuit 32 are synchronized.

  The one-round lighting periods TS1 and TS2 may be periodic at a speed that cannot be perceived by humans. For example, the frequency that is the reciprocal of the one-round lighting cycle may be 100 Hz or more.

  Here, “periodic at a speed that humans cannot perceive” means “not letting humans perceive flicker”. Regarding countermeasures against flickering of LED lighting, for example, “Electrical Appliance and Material Safety Law (PSE) commentary document,“ Electrical Appliance and Material Safety Law amendment enforced from July 1, 2012 ”) (Ministry of Economy, Trade and Industry) Standards are provided by the Product Safety Division of the Commercial Distribution Group. In “Explanation of flickering of light output” on page 28 of the same commentary document, a frequency that produces an effect equivalent to “light output does not feel flicker” is interpreted as follows. That is, in the explanation document, the requirements for satisfying that “the optical output does not flicker” are (1) the repetition frequency is 100 Hz or more and there is no missing portion in the optical output, and (2) the repetition frequency is 500 Hz. This is interpreted as one of the above.

  In the lighting apparatus of the present embodiment, it is considered that the light output is not missing in the examples of FIGS. 4A and 4B, so it is considered that the above (1) should be satisfied. In this case, the frequency that is the reciprocal of the round lighting cycle Ts may be 100 Hz or more.

  Alternatively, in the case where the configuration does not include the smoothing capacitors C2 to C5 in FIG. 3, it corresponds to the case where the optical output is lost, and it is considered that the above (2) should be satisfied. In this case, the frequency that is the reciprocal of the round lighting cycle Ts may be 500 Hz or more.

  As described above, the LED lighting device 30 according to the first embodiment is an LED lighting device 30 that lights a plurality of LED loads 21 to 24 having different emission colors, and powers the plurality of LED loads 21 to 24. A selector circuit 32 that feeds power to the selected LED load from the power supply circuit 31 by cyclically selecting one LED load among the plurality of LED loads 21 to 24 sequentially, And a control circuit 33 that controls the selector circuit 32. The control circuit 33 shortens the length of the power feeding section in which power is supplied from the power supply circuit 31 to each LED load as the dimming rate indicating the brightness decreases, and then selects the power feeding section of the selected LED load, and the next selection. A pause section in which no LED load is fed is provided between the LED load feeding sections, and the selector circuit 32 is controlled so that the pause section does not become long even if the dimming rate decreases.

  According to this, even if the dimming rate decreases, that is, the length of the pause period does not increase even if the illumination light becomes dark due to the dimming, it is possible to reduce the appearance of the emission colors appearing on a moving object quickly That is, color flicker can be reduced.

  Here, the selector circuit 32 includes a plurality of switching elements M3 to M6, and each of the plurality of switching elements M3 to M6 may be connected in series with any one of the plurality of LED loads 21 to 24. Good.

  Here, the control circuit 33 may control the selector circuit 32 so that the length of the pause section Tx is constant regardless of the dimming rate.

  According to this, since the pause section Tx is constant, the control of the control circuit 33 can be facilitated.

  Here, the power supply circuit 31 is a switching power supply including the inductor L1, and may supply power to the plurality of LED loads 21 to 24 via the inductor L1.

  According to this, the power supply circuit can be reduced in size, increased in efficiency, and reduced in cost.

  Here, the control circuit 33 may synchronize the switching operation in the power supply circuit 31 that is a switching power supply and the selection operation in the selector circuit 32.

  Here, the cycle in which the selection of the plurality of LED loads 21 to 24 completes may be shortened as the dimming rate decreases.

  According to this, the color flicker can be further reduced.

  In addition, the combination of the luminescent color of LED load 91-94 is not restricted to red, green, blue, and white.

(Embodiment 2)
In the first embodiment, as an example in which the length of the pause section does not increase even when the dimming rate decreases, the example in which the length of the pause section is constant is shown in FIG. In the second embodiment, an example in which the pause interval is shortened as the dimming rate is decreased will be described.

[2.1 Configuration of LED lighting device and lighting fixture]
The configuration of the lighting fixture 100 according to Embodiment 2 may be the same as that in FIGS. 1 and 3. However, the control performed by the selector circuit 32 by the control circuit 33 is different. Hereinafter, different points will be mainly described.

  The control circuit 33 controls the selector circuit 32 so that the length of the pause period is shortened as the dimming rate is small. That is, the length of the pause section is not constant, and becomes shorter as the dimming rate is smaller.

[2.2 Operation of LED lighting device and lighting fixture]
Next, the operation example of the lighting fixture 100 provided with the LED lighting device 30 which concerns on Embodiment 2 is demonstrated.

  FIG. 5 is a diagram illustrating a current waveform of the lighting fixture 100 having the LED lighting device 30 according to the second embodiment. The figure is different from FIG. 2 in that the length of the pause section changes according to the dimming rate. The pause section TX2 when the dimming rate is small, shown in the lower part of FIG. 5, is shorter than the pause period TX1 shown in the upper stage when the dimming rate is large.

  For example, the control circuit 33 may set the length of the pause interval to a value obtained by multiplying the length of the power supply interval by a coefficient. The control circuit 33 may set the length of the pause period to a value obtained by multiplying the pulse width of the gate voltage by a coefficient. Alternatively, the control circuit 33 may shorten the length of the pause interval stepwise in at least two steps as the dimming rate is smaller.

  As described above, in the LED lighting device 30 according to the second embodiment, the control circuit 33 controls the selector circuit 32 so as to shorten the length of the pause period as the dimming rate is smaller.

  According to this configuration, the color flicker can be reduced more than in the first embodiment.

(Embodiment 3)
In the third embodiment, an example in which the length of the pause period is counted using the timer 36 will be described.

[3.1 Configuration of LED lighting device and lighting fixture]
The configuration of the luminaire 100 according to Embodiment 3 may be the same as that in FIG. However, the control circuit 33 is configured by an MCU (Micro Controller Unit or Micro Computer Unit) that includes a processor, a memory, and a timer 36. The timer 36 is used to count the length of the pause period.

[3.2 Operation of LED lighting device and lighting apparatus]
Next, an operation example of the lighting fixture 100 including the LED lighting device 30 according to Embodiment 3 will be described.

  FIG. 6 is a diagram illustrating a current waveform of the lighting fixture 100 including the LED lighting device 30 according to the third embodiment. The figure shows an example of the same lighting operation as that in FIG. 2, and the one-round lighting cycle is fixed by the timer 36. In the example of FIG. 6, the timer 36 is programmed to start counting at the end of the power feeding interval and generate a timeout when counting a certain time, as shown in the lower part. The timer output in the figure rises to a high level at the start of counting, and falls to a low level at the end of counting for a certain time. Specifically, the control circuit 33 detects the end of the power feeding section by detecting that the inductor current has become 0, and starts counting of the timer 36 at the time of detection. Further, the control circuit 33 generates the gate voltage so as to select the next LED load in the round lighting when the timeout occurs.

  As described above, in the LED lighting device 30 according to the third embodiment, the control circuit 33 is configured by a microcomputer having the timer 36 and counts the length of the pause period using the timer 36.

  According to this, it is possible to facilitate periodic control for providing a pause interval by the control circuit 33.

  Note that the timer 36 may count not only the rest period but also the one-round lighting period and the power feeding periods Ta to Td. The timer 36 may have a configuration including one timer circuit or a configuration including a plurality of timer circuits.

  In the second embodiment, the pause interval may be counted using the timer 36.

(Embodiment 4)
Embodiment 4 demonstrates the example of the lighting fixture 100 provided with the LED lighting device 30 which concerns on said each embodiment using FIG. 7A-FIG. 7C.

  FIG. 7A is a diagram illustrating an appearance example of a lighting fixture 100 including the LED lighting device 30 according to each embodiment. FIG. 7A shows an appearance of a downlight 100a as an example of the lighting fixture 100.

  The downlight 100a includes a circuit box 101a, a lamp body 102a, and a wiring 103a. The circuit box 101a is a housing that houses all or part of the LED lighting device 30 according to each of the above embodiments. The lamp body 102a is a lamp body to which the light source 20 is attached. The wiring 103a electrically connects the circuit box 101a and the light source 20 in the lamp body 102a.

  FIG. 7B is a diagram illustrating another external appearance example of the lighting fixture 100 including the LED lighting device 30 according to each embodiment. In FIG. 7B, the external appearance of the spotlight 100b is shown as an example of the lighting fixture 100. The spotlight 100b includes a circuit box 101b, a lamp body 102b, and a wiring 103b. The circuit box 101b, the lamp body 102b, and the wiring 103b are the same as the circuit box 101a, the lamp body 102a, and the wiring 103a in FIG. 7A.

  FIG. 7C is a diagram illustrating still another external appearance example of the lighting fixture 100 including the LED lighting device 30 according to each embodiment. In FIG. 7C, the appearance of a spotlight 100 c is shown as an example of the lighting fixture 100. The spotlight 100c includes a circuit box 101c and a lamp body 102c. These are the same as the circuit box 101a and the lamp body 102b of FIG. 7A.

  In the fourth embodiment, the same effects as those of the above-described embodiments can be obtained.

  The LEDs d1 to d12 in the light source 20 are not limited to so-called light emitting diodes, but may be solid light emitting elements such as organic light emitting diodes (OLEDs) and laser light emitting elements.

  The LED lighting device according to one or more aspects of the present disclosure has been described based on the embodiment, but the present disclosure is not limited to the embodiment. Unless it deviates from the gist of the present disclosure, various modifications conceived by those skilled in the art in the present embodiment and forms constructed by combining components in different embodiments are also included in the scope of the present disclosure. May be.

21, 22, 23, 24 LED load 30 LED lighting device 31 power supply circuit 32 selector circuit 33 control circuit 36 timer 100 lighting fixtures C2, C3, C4, C5 smoothing capacitors d1 to d12 LED
Da, Db, Dc, Dd Diode L1 Inductor M3, M4, M5, M6 Switching element

Claims (9)

An LED lighting device for lighting a plurality of LEDs (Light Emitting Diode) loads having different emission colors,
A power supply circuit for supplying power to the plurality of LED loads;
A selector circuit that feeds power to the selected LED load from the power supply circuit by sequentially selecting one of the plurality of LED loads cyclically;
A control circuit for controlling the selector circuit,
The control circuit includes:
The smaller the dimming rate indicating the brightness, the shorter the length of the feeding section that feeds power from the power supply circuit to each LED load,
Between the power supply section of the selected LED load and the power supply section of the LED load to be selected next, a pause section in which any LED load is not supplied is provided,
An LED lighting device that controls the selector circuit so that the pause period does not become long even when the dimming rate is low. The selector circuit includes a plurality of switching elements,
The LED lighting device according to claim 1, wherein each of the plurality of switching elements is connected in series with any one of the plurality of LED loads. The control circuit controls the selector circuit so that the length of the pause period is constant regardless of the dimming rate.
The LED lighting device according to claim 1 or 2. The LED lighting device according to claim 1, wherein the control circuit controls the selector circuit so that the length of the pause period is shortened as the dimming rate is smaller. The LED lighting device according to any one of claims 1 to 4, wherein the power supply circuit is a switching power supply including an inductor, and supplies power to the plurality of LED loads via the inductor. The LED lighting device according to claim 2, wherein a cycle in which the selection of the plurality of LED loads is completed is shorter as the dimming rate is lower. The LED lighting device according to claim 1, wherein the control circuit includes a microcomputer having a timer, and counts the length of the pause period using the timer. LED lighting device according to any one of claims 1 to 7,
A lighting fixture comprising the plurality of LED loads. Each of the plurality of LED loads is
One or more LEDs;
A smoothing capacitor connected in parallel with the one or more LEDs;
The lighting apparatus according to claim 8, further comprising a backflow prevention diode connected in series with a parallel circuit including the one or more LEDs and the smoothing capacitor.

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