JP2014232603A - Lighting device, luminaire using the same and illumination system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device, a luminaire using the same and an illumination system capable of reducing deviation of dimming level from a desired dimming curve and light flicker.SOLUTION: A control circuit 13 controls dimming operation in two manners; i.e., a first dimming manner in which the brightness of a solid state light source 22 is controlled by increasing/reducing the current flowing to the solid state light source 22; and a second dimming manner in which the brightness of a solid state light source 22 is controlled by changing the ratio between the period to allow the current to flow to the solid state light source 22 and the period not to allow the current to flow to the solid state light source 22. During stable lighting with constant set value of a dimming signal S1, the control circuit 13 controls so that the changing cycle of dimming level in the first dimming manner is the same as the changing cycle of the dimming level in the second dimming manner. When the set value of the dimming signal S1 changes, the control circuit 13 controls the changing cycle of the dimming level in the first dimming manner to be shorter than that in the stable lighting, and controls the change amount of the dimming level to be smaller than the change amount of the dimming level per one cycle in the case when the changing cycle of the dimming level is not reduced.

Description

  The present invention relates to a lighting device, a lighting fixture using the lighting device, and a lighting system.

  2. Description of the Related Art Conventionally, there has been provided a lighting device that dimms a solid light source (for example, an LED or an organic EL) in accordance with a dimming signal (PWM signal) output from a dimmer (see, for example, Patent Document 1). This lighting device has a series circuit of a switching element and an inductor and supplies a direct current to the solid state light source, and a current flowing through the solid state light source by controlling on / off of the switching element of the power source circuit section. A current control unit for adjusting the amount.

  The current control unit includes a first control unit and a second control unit, and the first control unit increases or decreases the current flowing to the solid state light source by changing the ON width of the switching element, and adjusts the current according to the current. A solid light source is turned on at a light level (DC dimming). Further, the second control unit sets an operation period for turning on / off the switching element and a stop period for stopping the switching element, and changes the width of the operation period and the stop period in one cycle. A solid light source is turned on at a dimming level corresponding to the dimming level (burst dimming).

  This lighting device employs a dimming method using both DC dimming and burst dimming, and the dimming ratio in this case is obtained by multiplying the dimming ratio of DC dimming and the dimming ratio of burst dimming. Value.

JP 2012-204026 A

  In the lighting device shown in Patent Document 1 described above, when the DC light control and the burst light control are not synchronized, there is a possibility that the light control level greatly deviates from the desired light control curve. Further, even when the DC dimming and the burst dimming are synchronized, there is a possibility that the light flickers at the time of fading.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a lighting device capable of reducing a deviation of a dimming level from a desired dimming curve and reducing a flicker of light, and the same. An object of the present invention is to provide a lighting apparatus and a lighting system using the above.

  The lighting device of the present invention includes a switching circuit connected between a power source and a solid-state light source, and a control circuit that controls the switching circuit according to a dimming signal from the outside. The brightness of the solid light source is controlled by changing the ratio of the period during which current flows through the solid light source and the period during which current does not flow through the solid light source. The dimming control using the second dimming method is performed, and the dimming level change cycle of the first dimming method is synchronized with the dimming level change cycle of the second dimming method. During stable lighting without changing the set value of the dimming signal, the dimming level change cycle of the first dimming method and the dimming level change cycle of the second dimming method are set to the same cycle, and according to the dimming signal The solid-state light source is turned on at the dimming level, and the dimming signal is set. When the value changes, the change period of the dimming level in at least one of the first dimming method and the second dimming method is made shorter than that during stable lighting, and the change amount of the dimming level is set to the dimming level. It is characterized in that it is made smaller than the amount of change in the light control level per time when the change period is not shortened.

  In this lighting device, when the change amount of the set value of the dimming signal is smaller than the predetermined value, the control circuit sets the change amount of the dimming level in each of the first dimming method and the second dimming method. It is preferable that the amount of change in the light control level is smaller than the amount of change in the light control level per time when the light control level change cycle is not shortened.

  In this lighting device, the control circuit can set the change amount of the dimming level smaller than the other of the first dimming method and the second dimming method, and can stably change the dimming level change period. It is also preferable that the change amount of the dimming level is shorter than the change amount of the dimming level per time when the change period of the dimming level is not shortened.

  The lighting fixture of this invention is equipped with said lighting device, It is characterized by the above-mentioned.

  The illumination system of the present invention includes the lighting device described above.

  In the middle of the change of the dimming level, in at least one of the first dimming method and the second dimming method, the dimming level change cycle is made shorter than that during stable lighting, and the dimming level change amount is set to the dimming level. In this case, the change period of the light control level is set to be smaller than the amount of change of the light control level per time. As a result, it is possible to reduce the shift of the light control level from the desired light control curve and to reduce the flicker of light.

2 is a schematic circuit diagram illustrating an example of a lighting device according to Embodiment 1. FIG. It is a graph which shows the relationship between the on-duty of a light control signal in the same as above, and a light control ratio. (A) is a schematic diagram which shows the change cycle of the light control level at the time of the stable lighting in the above, (b) is a schematic diagram which shows the change cycle of the light control level at the time of the light control level change in the same as the above. (A) The change figure of the dimming level of DC dimming same as the above, (b) The change figure of the dimming level of burst dimming same as the above, (c) Combined the DC dimming and burst dimming same as the above. It is a change figure of the light control level in a case. (A) is a schematic diagram which shows the change cycle of the light control level at the time of the stable lighting in the lighting device of Embodiment 2, (b) is a schematic diagram which shows the change cycle of the light control level at the time of the light control level change in the same as the above. . (A) The change figure of the dimming level of DC dimming same as the above, (b) The change figure of the dimming level of burst dimming same as the above, (c) Combined the DC dimming and burst dimming same as the above. It is a change figure of the light control level in a case. (A), (b) is sectional drawing which shows an example of the lighting fixture using the lighting device of Embodiment 1 or 2. FIG.

  Hereinafter, embodiments of a lighting device, a lighting fixture using the lighting device, and a lighting system will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic circuit diagram illustrating an example of a lighting device 1 according to the present embodiment. The lighting device 1 includes a DC power supply circuit 10, a step-up chopper circuit 11, a step-down chopper circuit 12, and a control circuit 13, and the light control according to the light control signal S 1 output from the light control signal generator 7. The solid light source 22 is turned on at the level. In the following description, an LED (light emitting diode) is used as the solid light source 22, but the solid light source 22 is not limited to an LED, and may be, for example, an organic EL.

  The DC power supply circuit 10 includes an input filter 102 that attenuates a noise component included in the power supply voltage, and a rectifier circuit 103 that rectifies the AC voltage supplied from the AC power supply 101 into a DC voltage. The input filter 102 and the rectifier circuit 103 have a conventionally well-known configuration, and detailed description thereof is omitted here.

  The step-up chopper circuit 11 includes a switching element Q1 made of an n-type MOSFET, a transformer T1 having a primary winding N1 and a secondary winding N2, a diode D1, a smoothing capacitor C1, and a resistor R1.

  The primary winding N1 of the transformer T1 has one end connected to the output terminal on the high potential side of the rectifier circuit 103 and the other end connected to the drain of the switching element Q1. Further, the secondary winding N2 of the transformer T1 is connected to a second control unit 133, which will be described later, and functions as a detection circuit that detects a current flowing through the primary winding N1.

  The source of the switching element Q1 is connected to the output terminal on the low potential side of the rectifier circuit 103 via the resistor R1, and the gate of the switching element Q1 is connected to the second control unit 133. Further, the connection point between the source of the switching element Q1 and the resistor R1 is connected to the second control unit 133, and a voltage corresponding to the current flowing through the switching element Q1 during the ON period of the switching element Q1 is input to the second control unit 133. .

  A smoothing capacitor C1 is connected between the output terminals of the step-up chopper circuit 11. The smoothing capacitor C1 smoothes the DC power supplied via the primary winding N1 of the transformer T1, and the smoothed DC power is stepped down by the step-down chopper. Output to the circuit 12. A diode D1 is connected between the drain of the switching element Q1 and the smoothing capacitor C1 in such a direction that the anode is on the drain side and the cathode is on the smoothing capacitor C1 side.

  The step-down chopper circuit 12 includes a switching element Q2 made of an n-type MOSFET, a transformer T2 having a primary winding N3 and a secondary winding N4, a diode D2, a smoothing capacitor C2, and a resistor R2.

  The primary winding N3 of the transformer T2 has one end connected to the drain of the switching element Q2, and the other end connected to the cathode of the solid light source 22. Further, the secondary winding N4 of the transformer T2 is connected to a first control unit 132, which will be described later, and functions as a detection circuit that detects a current flowing through the primary winding N3. The anode of the solid light source 22 is connected to the output terminal on the high potential side of the boost chopper circuit 11.

  The source of the switching element Q2 is connected to the output terminal on the low voltage side of the boost chopper circuit 11 via the resistor R2, and the gate of the switching element Q2 is connected to the first control unit 132. Furthermore, the connection point between the source of the switching element Q2 and the resistor R2 is connected to the first control unit 132, and a voltage corresponding to the current flowing through the switching element Q2 during the ON period of the switching element Q2 is input to the first control unit 132. .

  A smoothing capacitor C2 is connected between the output terminals of the step-down chopper circuit 12. The smoothing capacitor C2 smoothes the DC power supplied via the primary winding N3 of the transformer T2, and the smoothed DC power is converted into a solid-state light source. 22 to output. A diode D2 is connected between the drain of the switching element Q2 and the output terminal on the high potential side of the step-up chopper circuit 11 so that the anode is on the drain side and the cathode is on the output terminal side.

  Here, in the present embodiment, the step-up chopper circuit 11 and the step-down chopper circuit 12 constitute a switching circuit.

  The control circuit 13 includes a microcomputer 131, a first controller 132, a second controller 133, and a signal converter 134, and a step-down chopper circuit according to the dimming signal S 1 output from the dimming signal generator 7. 12 operations are controlled.

  The signal conversion unit 134 converts the dimming signal S1 (PWM signal) output from the dimming signal generator 7 into a DC voltage corresponding to the on-duty width, and outputs the DC voltage to the A / D conversion port of the microcomputer 131.

  The microcomputer 131 (for example, R8C / 28, 29 group of Renesas Electronics Corporation) has a data table indicating the relationship between the on-duty of the dimming signal and the dimming level (dimming ratio).

  FIG. 2 is a graph showing an example of the data table. A straight line c in FIG. 2 indicates DC dimming (first dimming) that controls the brightness of the solid light source 22 by increasing or decreasing the current passed through the solid light source 22. The relationship between the on-duty of the dimming signal and the dimming ratio in the method) is shown.

  A curve b in FIG. 2 indicates a burst dimming (second dimming) that controls the brightness of the solid light source 22 by changing the ratio of the period during which current flows through the solid light source 22 and the period during which no current flows through the solid light source 22. The relationship between the on-duty of the dimming signal and the dimming ratio in the method) is shown.

  A curve a in FIG. 2 shows the relationship between the on-duty of the dimming signal and the dimming ratio in the dimming method using both DC dimming and burst dimming. In this case, the dimming ratio is DC dimming. It is a value obtained by multiplying the dimming ratio by the dimming ratio of burst dimming.

  The microcomputer 131 obtains the dimming ratio according to the on-duty of the dimming signal S1 output from the dimming signal generator 7, and then the DC dimming ratio and burst dimming corresponding to this dimming ratio. Is obtained from the data table. The microcomputer 131 generates an on-duty dimming signal S2 corresponding to the DC dimming ratio and an on-duty dimming signal S3 corresponding to the burst dimming ratio, and the generated dimming signal. S2 and S3 are output to the first controller 132.

  Here, the microcomputer 131 outputs the dimming signal S2 using a built-in 16-bit timer, and outputs the dimming signal S3 using an 8-bit timer.

  The second control unit 133 detects the current flowing through the primary winding N1 of the transformer T1 by the secondary winding N2, and turns on the switching element Q1 at the timing when the detected current value becomes zero. Is output (critical mode). Further, the second control unit 133 detects the current flowing through the switching element Q1 during the ON period of the switching element Q1, and turns off the switching element Q1 at a timing when the detected current value of the current reaches a predetermined first reference value. An off signal is output.

  Then, the second controller 133 controls the output voltage of the boost chopper circuit 11 to be a predetermined voltage by alternately outputting the on / off signal at a predetermined timing.

  The first control unit 132 detects the current flowing through the primary winding N3 of the transformer T2 by the secondary winding N4, and turns on the switching element Q2 at the timing when the detected current value becomes zero. Is output (critical mode). Further, the first control unit 132 detects the current flowing through the switching element Q2 during the ON period of the switching element Q2, and turns off the switching element Q2 when the detected current value reaches the predetermined second reference value. An off signal is output.

  And the 1st control part 132 is controlled so that the electric current sent through the solid light source 22 may turn into predetermined current by outputting the above-mentioned on / off signal alternately at predetermined timing.

  The first control unit 132 sets the second reference value based on the dimming signal S2 output from the microcomputer 131, and further operates an operation period for turning on / off the switching element Q2 based on the dimming signal S3. Set the stop period to stop. Then, the first control unit 132 controls on / off of the switching element Q2 based on the second reference value during the operation period, and as a result, the solid state light source at a dimming level according to the dimming signals S2 and S3. 22 lights up.

  In the lighting device 1 described above, when the change cycle of the dimming level for DC dimming and the change cycle of the dimming level for burst dimming are set to the same cycle, the dimming level for DC dimming is as shown in FIG. It changes as shown by a broken line e, and the dimming level of burst dimming changes as shown by a solid line f in FIG. In the dimming method using both DC dimming and burst dimming, the dimming level changes as indicated by the broken line h in FIG. 4C, and the dimming level deviates greatly from the dimming curve. . Here, the dimming curve refers to a dimming curve obtained by changing the dimming level in an analog manner.

  In the present embodiment, in the case where DC dimming and burst dimming are used in combination, the dimming level change period and change amount of the DC dimming level so as to reduce the deviation of the dimming level from the dimming curve, and The change period and change amount of the dimming level for burst dimming are set as follows. The minimum change period T1 of the dimming level for DC dimming is 1/5 of the minimum change period T2 for the dimming level of burst dimming.

  At the time of stable lighting in which the dimming level (setting value of the dimming signal S1) does not change, as shown in FIG. 3A, the dimming level change period T3 of DC dimming is equivalent to 10 periods of the minimum change period T1. And the dimming level change period T4 of the burst dimming is set to two periods of the minimum change period T2. That is, in this case, the dimming level change period T3 for DC dimming and the dimming level change period T4 for burst dimming are set to the same period.

  Regarding the amount of change in the dimming level of DC dimming and the amount of change in the dimming level of burst dimming, the dimming level (dimming ratio) is the dimming curve with respect to the on-duty of the dimming signal S1. It is obtained by referring to the data table so as to have the above value.

  When the dimming level (set value of the dimming signal S1) changes, as shown in FIG. 3B, the dimming level change period T3 of DC dimming is set to two periods of the minimum change period T1. The dimming level change period T4 of the burst dimming is set to two periods of the minimum change period T2. That is, in this case, the dimming level change cycle T3 of DC dimming is set to 1/5 of the stable lighting, the dimming level change cycle T3 of DC dimming, and the dimming level change cycle T4 of burst dimming. Are synchronized.

  Further, the amount of change in the light control level of DC light control is set to 1/5 of the amount of change in the light control level per time when the light control level change period is not shortened. That is, in this case, the dimming level change cycle T3 of DC dimming is shorter than that during stable lighting, and the amount of change in the dimming level of DC dimming is set to 1 when the dimming level change cycle is not shortened. It is smaller than the amount of change in the light control level per time.

  In DC dimming, as shown by a solid line d in FIG. 4A, the dimming level decreases stepwise at the timing when the change cycle T3 elapses, and the time corresponding to 15 cycles of the change cycle T3. At the time t3 when the time elapses, the light control level at the time of stable lighting is obtained. In burst dimming, as shown by the solid line f in FIG. 4B, the dimming level decreases stepwise at the timing when the change cycle T4 elapses, and two cycles of the change cycle T4 elapse. At the time t2 (t2 <t3), the light control level at the time of stable lighting is obtained.

  As a result, in the dimming method using both DC dimming and burst dimming, the dimming level is stepped at the timing when the DC dimming change period T3 elapses, as shown by the solid line g in FIG. The light control level at the time of stable lighting is reached at time t3. Thereby, the shift of the dimming level from the dimming curve is reduced as compared with the case where the dimming level change cycle T3 of DC dimming and the dimming level change cycle T4 of burst dimming are set to the same cycle. be able to.

  4A to 4C, the section before time t1 and the section after time t3 are sections where the solid light source 22 is stably lit.

  According to the present embodiment, during the change of the dimming level, the cycle of changing the dimming level of the DC dimming is made shorter than that during stable lighting, and the amount of change in the dimming level of the DC dimming is adjusted. The change amount of the light control level per time when the level change cycle is not shortened is set to be smaller. As a result, the deviation of the light control level from the desired light control curve can be reduced, and the light flicker can be reduced.

  Here, when the change amount of the dimming level can be set to be smaller in the case of the DC dimming than the burst dimming, the dimming level change period and the change amount may be changed in the DC dimming. In addition, when burst dimming can set the amount of change in dimming level smaller than DC dimming, the dimming level change period and amount of change may be changed in burst dimming.

  Thereby, since the light control level can be changed further in small steps, the shift of the light control level from the light control curve can be further reduced. Further, the control can be simplified as compared with the case where the amount of change in the light control level is reduced in each of the DC light control and the burst light control.

  In the present embodiment, the DC power supply circuit 10 that converts the AC voltage supplied from the AC power supply 101 into a desired DC voltage is used. However, a DC power supply may be connected to the boost chopper circuit 11. The form is not limited. In this embodiment, both the step-up chopper circuit 11 and the step-down chopper circuit 12 are used as the switching circuit, but the step-up chopper circuit 11 may be omitted.

  Further, in the present embodiment, the step-down chopper circuit 12 is used as a circuit for controlling the current flowing to the solid-state light source 22, but a step-up chopper circuit, a step-up / step-down chopper circuit, a flyback converter circuit, or the like may be used. The form is not limited.

(Embodiment 2)
Embodiment 2 of the lighting device will be described with reference to FIGS. 5 and 6. In the first embodiment, only the change period and change amount of the dimming level of the DC dimming are changed. However, when the change amount of the dimming level (set value of the dimming signal S1) is smaller than a predetermined value, the DC dimming is performed. It is preferable to change the change period and change amount of the light control level in each of the burst light control and the burst light control. This will be specifically described below. Note that the circuit configuration of the lighting device 1 is the same as that of the first embodiment, and a description thereof will be omitted here. The minimum dimming level change period T1 for DC dimming is 1/5 of the minimum dimming level change period T2 for burst dimming.

  At the time of stable lighting in which the dimming level (the set value of the dimming signal S1) does not change, as shown in FIG. 5A, the dimming level change period T3 of DC dimming is equivalent to 10 periods of the minimum change period T1. And the dimming level change period T4 of the burst dimming is set to two periods of the minimum change period T2. That is, in this case, the dimming level change period T3 for DC dimming and the dimming level change period T4 for burst dimming are set to the same period.

  Regarding the amount of change in the dimming level of DC dimming and the amount of change in the dimming level of burst dimming, the dimming level (dimming ratio) is the dimming curve with respect to the on-duty of the dimming signal S1. It is obtained by referring to the data table so as to have the above value.

  When the dimming level (the set value of the dimming signal S1) changes, as shown in FIG. 5B, the dimming level change period T3 of DC dimming is set to two periods of the minimum change period T1. The change period T4 of the dimming level for burst dimming is set to one period of the minimum change period T2. That is, in this case, the dimming level change period T3 of DC dimming is set to 1/5 of stable lighting, the dimming level change period T4 of burst dimming is set to 1/2 of stable lighting, and DC dimming is further performed. The dimming level change period T3 is synchronized with the burst dimming level change period T4.

  Further, the amount of change in the light control level of DC light control is set to 1/5 of the amount of change in the light control level per time when the light control level change period is not shortened. Furthermore, the amount of change in the light control level of burst light control is set to ½ of the amount of change in the light control level per time when the change period of the light control level is not shortened. That is, in this case, in each of the DC dimming and the burst dimming, the dimming level change cycle is made shorter than that in stable lighting, and the dimming level change amount is not shortened. It is smaller than the amount of change in the light control level per time.

  In DC dimming, as indicated by the solid line j in FIG. 6A, the dimming level decreases stepwise at the timing when the change cycle T3 elapses, and the time corresponding to 15 cycles of the change cycle T3 is reached. At the time t3 when the time elapses, the light control level at the time of stable lighting is obtained. In burst dimming, as indicated by the solid line k in FIG. 6B, the dimming level decreases stepwise at the timing when the change cycle T4 elapses, and five cycles of the change cycle T4 elapse. At the time t2 (t2 <t3), the light control level at the time of stable lighting is obtained.

  As a result, in the dimming method using both DC dimming and burst dimming, as shown by the solid line m in FIG. 6C, dimming is performed at the timing when the change cycle T3 elapses and at the timing when the change cycle T4 elapses. The level gradually decreases in a stepped manner, and becomes a dimming level at the time of stable lighting at time t3.

  Thereby, the shift of the dimming level from the dimming curve is reduced as compared with the case where the dimming level change cycle T3 of DC dimming and the dimming level change cycle T4 of burst dimming are set to the same cycle. be able to. In addition, the amount of change in the dimming level in either one of DC dimming or burst dimming is smaller than that in a case where the dimming level change amount per one time when the dimming level changing period is not shortened. Thus, the flicker of light can be further reduced and the degree of freedom in design can be improved.

(Embodiment 3)
Embodiment of the lighting fixture A using the lighting device 1 of the above-mentioned Embodiment 1 or 2 is described, referring FIG.

  FIG. 7A is a cross-sectional view showing an example of the lighting fixture A of the present embodiment. The lighting fixture A includes a lighting device 1, a light source unit 2, a fixture body 3, and a translucent panel 4. The lighting device 1 and the instrument body 3 are provided separately.

  The instrument body 3 is formed in a rectangular box shape with an open bottom surface, and is embedded in the back of the ceiling through an embedding hole 100 a provided in the ceiling material 100. Moreover, the translucent panel 4 formed in the rectangular plate shape is attached to the opening surface of the instrument main body 3 by an appropriate method.

  The light source unit 2 includes a substrate 21 formed in a rectangular plate shape, and a plurality (three in FIG. 7A) of solid light sources 22 mounted on the substrate 21. The instrument body 3 is housed in the lower direction. Further, the substrate 21 is electrically connected to the lighting device 1 through the electric wire 5, and lighting power is supplied from the lighting device 1.

  FIG. 7B is a cross-sectional view showing another example of the lighting fixture A. In this example, the lighting device 1 described above is housed inside the fixture body 3, and a heat radiating plate 61 is attached to the back surface of the substrate 21 of the light source unit 2. In addition, since the structure of other than that is the same as that of the lighting fixture A shown to Fig.7 (a), description is abbreviate | omitted here.

  According to the present embodiment, the lighting fixture A includes the lighting device 1 described in the first or second embodiment, thereby reducing the deviation of the dimming level from the desired dimming curve and reducing the flicker of light. A lighting fixture A can be provided.

  Here, as a lighting system provided with the lighting device 1, for example, a lighting system that simultaneously controls a plurality of lighting fixtures A with a dimming signal S <b> 1 output from the dimming signal generation device 7 can be cited. By providing the lighting device 1 described in the first or second embodiment, the illumination system can provide a lighting system that can reduce the deviation of the dimming level from the desired dimming curve and reduce the flicker of light. Can do.

13 Control circuit 22 Solid light source S1 Dimming signal

Claims (5)

A switching circuit connected between a power source and a solid-state light source, and a control circuit for controlling the switching circuit in response to a dimming signal from the outside,
The control circuit includes a first dimming method for controlling brightness of the solid light source by increasing / decreasing a current flowing to the solid light source, a period in which current flows to the solid light source, and a period in which no current flows to the solid light source The dimming control using the second dimming method for controlling the brightness of the solid state light source by changing the ratio of the first dimming method and the second dimming method are performed. Is synchronized with the dimming level change cycle.
The control circuit is configured so that the change cycle of the dimming level of the first dimming method and the change cycle of the dimming level of the second dimming method are the same during stable lighting when the set value of the dimming signal does not change. And lighting the solid state light source at a dimming level according to the dimming signal,
When the set value of the dimming signal has changed, the dimming level change period in at least one of the first dimming method and the second dimming method is shorter than that during the stable lighting, and dimming is performed. A lighting device characterized in that the amount of change in level is made smaller than the amount of change in light control level per time when the change cycle of the light control level is not shortened.   When the change amount of the set value of the dimming signal is smaller than a predetermined value, the control circuit sets the change amount of the dimming level in each of the first dimming method and the second dimming method. The lighting device according to claim 1, wherein the light control level change period is set to be smaller than a change amount of the light control level per time when the change period of the light control level is not shortened.   The control circuit can set the change amount of the dimming level to be smaller than the other of the first dimming method and the second dimming method, and the change cycle of the dimming level is shorter than that during the stable lighting. The lighting device according to claim 1, wherein the amount of change in the light control level is made smaller than the amount of change in the light control level per time when the change period of the light control level is not shortened.   A lighting fixture comprising the lighting device according to any one of claims 1 to 3.   An illumination system comprising the lighting device according to claim 1.

Images