LED lighting device, lighting fixture, and lighting system

Abstract

To provide an LED lighting device capable of suppressing chattering when switching the dimming control mode without adding any circuit components.SOLUTION: An LED lighting device 10 includes: a converter 1 that receives a dimming signal from outside and supplies the output to an LED light source 2; and a control circuit 3 that controls the output from the converter 1 to the LED light source 2. The control circuit 3 includes: a first dimming control circuit 32 for controlling the converter 1 with the first control mode; a second dimming control circuit 34 for controlling the converter 1 with the second control mode; and a dimming control switching circuit 36 that switches between the first dimming control circuit 32 and the second dimming control circuit 34 depending on the dimming level value corresponding to the dimming signal. The dimming control switching circuit 36 has a period during which switching between the first dimming control circuit 32 and the second dimming control circuit 34 is suppressed regardless of the dimming level either before or after switching between the first dimming control circuit and the second dimming control circuit after detecting that the dimming level has exceeded the predetermined threshold.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an LED lighting device, a lighting fixture, and a lighting system.

Background Art

[0002] In recent years, digital control equipped with a microcomputer has become mainstream in the control of converters used for power control of LED lighting devices. Digital control using a microcomputer has the advantages that changes and modifications to the control method can be easily implemented by rewriting the program, and it can easily handle the specifications of multiple loads. Furthermore, dimming control of LED light sources can also be easily realized.

[0003] As control methods for switching elements in converter power control, a continuous current mode (CCM), a discontinuous current mode (DCM), and a boundary current mode (BCM) are known. The continuous current mode (CCM) is a control method in which the switching element is turned on before the inductor current becomes zero, and the inductor current flows continuously. CCM is used when the load power is relatively large because the peak current is small. The discontinuous current mode (DCM) is a control method in which there is a period during each switching cycle when the inductor current becomes zero, and it is used when the load power is relatively small because the peak current is large. The boundary current mode (BCM) is a control method in which the switching element is turned on immediately when the inductor current becomes zero, and control is performed under the boundary conditions between CCM and DCM.

[0004] BCM (Boundary Current Mode) has low switching loss and is advantageous from the perspective of improving the efficiency of LED lighting devices. However, in BCM, there are problems that the switching frequency increases and the noise terminal voltage becomes large during low-beam dimming with reduced output power. Also, since it cannot be controlled at a high switching frequency exceeding the control performance limit of the control circuit, there is a limit to low-beam dimming.

[0005] Therefore, in a region lower than a predetermined dimming level, a measure can be considered to suppress the noise terminal voltage while maintaining high efficiency of the LED lighting device by switching the control method to DCM (discontinuous current mode).

[0006] When switching the dimming control method of the converter, the switching of the dimming control method is performed using the dimming level corresponding to a predetermined dimming signal as a threshold value. When the dimming level crosses the threshold value, so-called chattering may occur, in which the switching of the dimming control method frequently occurs near the threshold value. When chattering occurs during the switching of the dimming control method in the converter, the operation of the converter becomes unstable, and there is a risk of flicker due to malfunction of the LED lighting device.

[0007] Patent Document 1 describes an LED power supply device that prevents chattering by providing hysteresis to the threshold value of the dimming level when switching the dimming control method. As a method of suppressing chattering by providing hysteresis to the threshold value, a method of setting, using a hysteresis comparator, the threshold value for switching the dimming control method when the dimming level increases to be larger than the threshold value for switching the dimming control method when the dimming level decreases can be considered.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] A hysteresis comparator is required for a method of preventing chattering by providing hysteresis to the threshold value when switching the control method. It is necessary to add an analog circuit separately, which is disadvantageous in terms of miniaturization and cost of the LED power supply device.

[0010] An object of the present disclosure is to provide an LED lighting device capable of suppressing chattering when switching a dimming control method without adding circuit components.

Means for Solving the Problems

[0011] The LED lighting device according to the present disclosure is an LED lighting device including a converter that receives a dimming signal from the outside and supplies an output to an LED light source, and a control circuit that controls the output from the converter to the LED light source. The control circuit includes a first dimming control circuit that controls the converter in a first control method, a second dimming control circuit that controls the converter in a second control method, and a dimming control switching circuit that switches between the first dimming control circuit and the second dimming control circuit according to the value of the dimming level corresponding to the dimming signal. The dimming control switching circuit has a period for suppressing the switching between the first dimming control circuit and the second dimming control circuit regardless of the value of the dimming level, either before or after detecting that the dimming level has exceeded a predetermined threshold and before switching between the first dimming control circuit and the second dimming control circuit.

Effects of the Invention

[0012] The LED lighting device according to the present disclosure can suppress chattering when switching the dimming control method without adding circuit components.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following description, specific shapes, materials, directions, numerical values, etc. are examples for facilitating the understanding of the present disclosure and can be appropriately changed according to applications, purposes, specifications, etc. Also, it is initially assumed that the components of the embodiments and modification examples described below can be selectively combined.

[0015] <First Embodiment> With reference to FIGS. 1 and 2, the configuration of the first embodiment of the present disclosure will be described. FIG. 1 is a block diagram of the LED lighting device of the present disclosure.

[0016] The LED lighting device 10 receives the voltage of the AC power supply 6 and supplies current to the LED light source 2. At this time, the LED lighting device 10 performs dimming by supplying a current corresponding to the dimming signal Dim from the external dimming controller 4 to the LED light source 2. The LED lighting device 10 includes a rectifying section 5 that rectifies and smoothes the AC voltage of the AC power supply 6, a converter 1 that outputs a current obtained by power-converting the DC voltage output by the rectifying section 5 to the LED light source 2, and a control circuit 3 that controls the converter 1. The LED lighting device 10 shown in FIG. 1 includes a constant current circuit 7, but the constant current circuit 7 is not an essential configuration.

[0017] Converter 1 outputs current to LED light source 2 by on-off controlling the switching elements (Figure 2, Q1) that make up Converter 1 according to the control signal from control circuit 3. Converter 1 performs dimming by changing the switching frequency or the on-width of the control signal that turns the switching elements on and off according to the dimming level corresponding to the dimming signal Dim. As the converter 1, a DC / DC conversion circuit such as a buck converter (see Figure 2) or a buck-boost converter (see Figure 8) is employed, but it is not limited thereto.

[0018] The LED light source 2 emits light that is approximately proportional to the current value in response to the current output from the converter 1.

[0019] The control circuit 3 has a first control method and a second control method as dimming control methods, and has a function of controlling the output from the converter 1 to the LED light source 2. The control circuit 3 switches between the first control method and the second control method according to the dimming signal Dim input from the external dimming controller 4. By switching the dimming control method, it is possible to suppress an increase in the switching frequency of the converter 1 and suppress the noise terminal voltage while performing dimming control of the LED light source 2. Here, the control circuit 3 is composed of a microcontroller or the like.

[0020] The control circuit 3 further includes a dimming control switching circuit 36 (see Figure 2) that suppresses chattering during switching of the dimming control method described later.

[0021] The dimming controller 4 is provided outside the LED lighting device 10 and outputs a dimming signal Dim as a dimming instruction value to the LED lighting device 10. The dimming instruction value corresponding to the dimming signal Dim is the dimming level in the LED lighting device 10. By changing the dimming signal Dim of the dimming controller 4, the current output from the converter 1 to the LED light source 2 is controlled to perform dimming control. Hereinafter, in the present disclosure, the "dimming level" shall mean the dimming instruction value corresponding to the dimming signal Dim.

[0022] The rectifying section 5 is an AC / DC conversion circuit that receives the AC voltage of the AC power supply 6 and converts it into a DC voltage. The rectifying section 5 is configured by, for example, a full-wave rectifier circuit, and may include a capacitor that smooths the output voltage at the output terminal of the full-wave rectifier circuit. The output voltage of the rectifying section 5 is input to the converter 1, power-converted by the converter 1, and output to the LED light source 2.

[0023] The constant current circuit 7 controls the current value output to the LED light source 2 to be constant according to the dimming instruction value input via the control circuit 3. Even if the output voltage of the rectifying section 5 has a ripple, the current ripple output to the LED light source 2 can be suppressed by the constant current circuit 7, so a stable light output can be obtained.

[0024] The LED lighting device 10 of the present disclosure will be described in detail with reference to FIG. 2. FIG. 2 is a circuit diagram of the converter of the first embodiment. In the first embodiment, a buck converter is adopted as the converter.

[0025] The converter 1 inputs the DC voltage Vdc, which is the output voltage of the rectifying section 5. The switching element Q1 is turned on and off by the control signal S1 output by the control circuit 3. The switching element Q1 is, for example, a MOSFET. The control signal S1 is input to the gate of the MOSFET, and the switching element Q1 turns on and off. The inductor L1 conducts current according to the on and off of the switching element Q1 and outputs it to the subsequent capacitor C1 and the LED light source 2.

[0026] The diode D1 turns on when the switching element Q1 is in the off state and regenerates the current of the inductor L1. The capacitor C1 is connected in parallel with the LED light source 2 and generates a substantially constant DC voltage according to the current of the inductor L1.

[0027] The control circuit 3 outputs a control signal S1 (on-off signal) to the switching element Q1. The control circuit 3 includes a first dimming control circuit 32, a second dimming control circuit 34, a dimming control switching circuit 36, and a constant current control circuit 38. The first dimming control circuit 32 or the second dimming control circuit 34 outputs a control signal S1 to the switching element Q1 according to the dimming signal Dim. The dimming control switching circuit 36 switches between the first dimming control circuit 32 and the second dimming control circuit 34 according to the input dimming signal Dim.

[0028] The first dimming control circuit 32 outputs a control signal S1 by BCM. The second dimming control circuit 34 outputs a control signal S1 by DCM.

[0029] The first dimming control circuit 32 controls the converter 1 by BCM. Specifically, when the control signal S1 is on, the switching element Q1 is on, and the current flowing through the inductor L1 increases. On the other hand, when the control signal S1 is off, due to the electromotive force generated in the inductor L1, current flows through the capacitor C1 and the LED light source 2, and the diode D1 is on. The first dimming control circuit 32 detects the timing when the current of the inductor L1 becomes zero according to the voltage of the winding n2 of the inductor L1, and outputs an on signal of the control signal S1 to the switching element Q1. Thus, according to BCM, since the switching element Q1 is on at the timing when the current of the inductor L1 becomes zero, there is no zero current period in the inductor L1, and the circuit efficiency is improved.

[0030] When dimming control is performed by BCM, the switching frequency of the switching element Q1 becomes the minimum value when the dimming level is 100% (full output). As the dimming level decreases (the current of the LED light source 2 decreases), the switching frequency increases.

[0031] In the converter 1 of the present disclosure, at a high dimming level from 100% (full output) to the threshold value, dimming control is performed by BCM, and at a low dimming level from the threshold value to the lower limit value, dimming control is performed by DCM described later. By switching the control method, it is possible to prevent the switching frequency from becoming too high and suppress the noise terminal voltage. The switching frequency of BCM when the dimming level corresponds to the threshold value is fsw1.

[0032] The second dimming control circuit 34 controls the converter 1 in DCM. Specifically, the switching element Q1 is turned on and off at a constant switching frequency fsw2. The second dimming control circuit 34 performs dimming by reducing the effective value of the current flowing through the inductor L1 by reducing the on-width of the control signal S1 according to the dimming level. Since the switching frequency is constant, as the dimming level decreases, the zero-current period of the inductor L1 becomes longer.

[0033] The switching frequency fsw2 in DCM is set lower than the switching frequency fsw1 when the dimming level corresponds to the threshold value in BCM. When reducing the output in DCM, it is necessary to shorten the on-time of the switching element Q1. If control is performed in DCM so as to lower the dimming level at the switching frequency fsw1, the on-time of the switching element Q1 may become too short and exceed the control performance limit. Therefore, in DCM, by setting the switching frequency to fsw2 lower than the switching frequency fsw1, it is possible to prevent exceeding the control performance limit.

[0034] The constant current circuit 7 is connected in series to the LED light source 2. The constant current circuit 7 is not an essential configuration of the LED lighting device 10, but has a function of controlling the current of the LED light source 2 to a constant value according to the signal S3 from the constant current control circuit 38 described later.

[0035] The constant current control circuit 38 outputs a signal S3 corresponding to the dimming signal Dim. The constant current control circuit 38 and the constant current circuit 7 control the current value of the LED light source 2 to be constant according to the value corresponding to the dimming signal Dim.

[0036] <First Embodiment> FIGS. 3 and 4 are diagrams for explaining the switching of the dimming control method according to the first embodiment. The horizontal axis represents the dimming level corresponding to the dimming signal Dim, and the vertical axis represents the switching frequency of the switching element Q1. The control characteristics by BCM and DCM are indicated by solid lines respectively. In the following description, the points on the control characteristics of BCM and DCM are referred to as control points.

[0037] FIG. 3 shows the switching of the dimming control method when dimming from a high dimming level to a low dimming level. The dimming control method in the region of a high dimming level where the dimming level is from 100% to the threshold value is BCM. In BCM, when the dimming level is decreased, the switching frequency increases. Here, let the control point of BCM at the threshold value be B0. When the dimming level is decreased from a high dimming level to a low dimming level and it is detected that the dimming level has exceeded the threshold value, that is, the control point B0, the dimming control switching circuit 36 switches the dimming control method from the first dimming control circuit 32 (BCM) to the second dimming control circuit 34 (DCM). At this time, the control point switches from the control point B0 of BCM to the control point D0 of DCM. In the present disclosure, when it is said that "the dimming level exceeds the threshold value", it includes both the case where the dimming level changes from a level higher than the threshold value to a level lower than the threshold value and the case where the dimming level changes from a level lower than the threshold value to a level higher than the threshold value.

[0038] Thereafter, after the dimming control switching circuit 36 switches the dimming control method from BCM to DCM, for a predetermined time, regardless of the value of the dimming level, the switching of the dimming control method is suppressed and DCM is maintained. Even when the dimming level straddles the threshold value, for example, when the dimming level fluctuates between the control points D1 and D2, it is controlled to maintain DCM. By controlling to maintain DCM for a predetermined time after switching the dimming control method from BCM to DCM, regardless of the value of the dimming level, chattering can be suppressed.

[0039] After a predetermined time has elapsed since the dimming control method is switched from BCM to DCM, the dimming control switching circuit 36 detects the dimming level and switches to a dimming control method according to the detected value of the dimming level. Specifically, when the detected value of the dimming level is lower than the threshold value, for example, in the case of the dimming level corresponding to the control point D1, DCM is maintained. When the detected value of the dimming level is higher than the threshold value, for example, in the case of the dimming level corresponding to the control point D2, the control point is switched to B1 and the dimming control method is switched to BCM.

[0040] Figure 4 shows the switching of the dimming control method when dimming from a low dimming level to a high dimming level. The dimming control method in the region of the low dimming level from the lower limit to the threshold value of the dimming level is DCM. In DCM, the switching frequency fsw2 is kept constant regardless of the value of the dimming level. Here, let the control point of DCM at the threshold value be D0. When increasing the dimming level from a low dimming level to a high dimming level and detecting that the dimming level has exceeded the threshold value, that is, the control point D0, the dimming control switching circuit 36 switches the dimming control method from the second dimming control circuit 34 (DCM) to the first dimming control circuit 32 (BCM). At this time, the control point switches from the control point D0 of DCM to the control point B0 of BCM.

[0041] Thereafter, the dimming control switching circuit 36 suppresses the switching of the dimming control method and maintains BCM for a predetermined time after switching the dimming control method from DCM to BCM, regardless of the value of the dimming level. Even when the dimming level crosses the threshold value, for example, when the dimming level fluctuates between the control point B1 and the control point B2, it is controlled to maintain BCM. By controlling to maintain BCM for a predetermined time after switching the dimming control method from DCM to BCM, regardless of the value of the dimming level, chattering can be suppressed.

[0042] After a predetermined time has elapsed since the dimming control method is switched from DCM to BCM, the dimming control switching circuit 36 detects the dimming level and switches to a dimming control method according to the detected value of the dimming level. Specifically, when the detected value of the dimming level is higher than the threshold value, for example, in the case of the dimming level corresponding to the control point B1, BCM is maintained. When the detected value of the dimming level is lower than the threshold value, for example, in the case of the dimming level corresponding to the control point B2, the control point is switched to D1 and the dimming control method is switched to DCM.

[0043] If a predetermined time has elapsed since the dimming control method was switched, it is assumed that the dimming level is at a point sufficiently far from the threshold value, and it is considered that chattering will not occur even if the dimming control method is switched according to the dimming level at that time.

[0044] Even if the dimming level remains near the threshold value, if the control shown in FIG. 3 or FIG. 4 is executed, the switching of the dimming control method is suppressed for a predetermined time after switching between the first dimming control circuit 32 and the second dimming control circuit 34, so that chattering due to the switching of the dimming control method can be suppressed. The predetermined time is preferably determined according to the change speed of the dimming signal Dim received by the LED lighting device 10.

[0045] As described above, in the LED lighting device 10 of the present disclosure, for a predetermined time after the dimming control method is switched when the dimming level (dimming signal Dim) reaches a predetermined threshold value, regardless of the value of the dimming level (dimming signal Dim), the switching between the first dimming control circuit 32 and the second dimming control circuit 34 is suppressed, so that chattering at the time of switching the dimming control method can be suppressed. Further, since the LED lighting device 10 of the present disclosure does not employ hysteresis control for suppressing chattering, the dimming control switching circuit 36 can be realized by a program of a microcontroller included in the control circuit 3, and no additional circuit components are required.

[0046] Using FIG. 5, the switching of the dimming control method with hysteresis in the threshold value will be described. FIG. 5 is a diagram for explaining the switching of the dimming control method with hysteresis in the comparative example.

[0047] <Comparative Example> Using FIG. 5, first, the switching of the dimming control method when dimming from a high dimming level to a low dimming level will be described. The dimming control method in the region of the high dimming level where the dimming level is from 100% to the threshold value 2 (<threshold value 1) is BCM. Here, let the control point of BCM at the threshold value 2 be Y2. When the dimming level is decreased from the high dimming level toward the low dimming level and the dimming level reaches the threshold value 2, that is, the control point Y2, the dimming control switching circuit 36 switches the dimming control method from the first dimming control circuit 32 (BCM) to the second dimming control circuit 34 (DCM). At this time, the control point switches from the control point Y2 of BCM to the control point X2 of DCM. When the dimming level further decreases, DCM is maintained.

[0048] Next, the switching of the dimming control method when dimming from a low dimming level to a high dimming level will be described. The control method in the region of the low dimming level where the dimming level is from the lower limit to the threshold value 1 (>threshold value 2) is DCM. Here, let the control point of DCM at the threshold value 1 be X1. When the dimming level is increased from the low dimming level toward the high dimming level and the dimming level reaches the threshold value 1, that is, the control point X1, the dimming control switching circuit 36 switches the dimming control method from the second dimming control circuit 34 (DCM) to the first dimming control circuit 32 (BCM). At this time, the control point switches from the control point X1 of DCM to the control point Y1 of BCM. When the dimming level further increases, BCM is maintained.

[0049] As shown above, when implementing hysteresis control, it is necessary to set two threshold values, which makes the design complicated. Also, additional circuit components such as a hysteresis comparator are required.

[0050] Referring to FIGS. 6 and 7, the switching of the dimming control method in another embodiment will be described. FIGS. 6 and 7 are diagrams for explaining the switching of the dimming control method of the second embodiment.

[0051] <Second Embodiment> In the second embodiment, the configurations of the converter 1 and the control circuit 3 are the same as those in the first embodiment. Also, the relationship between the dimming level and the switching frequency in BCM and DCM is generally the same as that in the first embodiment. The second embodiment is different from the first embodiment in the switching control of the dimming control method near the threshold value of the dimming level, which is the dimming instruction value corresponding to the dimming signal Dim of the dimming control switching circuit 36, and the description will be focused on this difference.

[0052] FIG. 6 shows the switching of the dimming control method when dimming from a high dimming level to a low dimming level. When the dimming level is decreased from a high dimming level to a low dimming level and it is detected that the dimming level has exceeded the threshold value, that is, the control point B0, different from the first embodiment, the dimming control switching circuit 36 does not switch the dimming control method and maintains BCM.

[0053] Thereafter, the dimming control switching circuit 36 suppresses the switching of the dimming control method and maintains BCM for a predetermined time after detecting that the dimming level has exceeded the threshold value, regardless of the value of the dimming level. That is, even if the dimming level exceeds the threshold value and further shifts to a lower dimming level, the BCM is maintained for the dimming control method, and the control point shifts from the control point B0 of BCM to the control point B2. Even when the dimming level straddles the threshold value, for example, when the dimming level fluctuates between the control points B1 and B2, it is controlled to maintain BCM. By controlling to maintain BCM for a predetermined time after the dimming level exceeds the threshold value, regardless of the value of the dimming level, chattering can be suppressed.

[0054] After a predetermined time has elapsed, the dimming control switching circuit 36 detects the dimming level and switches to a dimming control method according to the value of the detected dimming level. Specifically, when the value of the detected dimming level is lower than the threshold value, for example, in the case of the dimming level corresponding to control point B2, the control point is switched to D2 and the dimming control method is switched to DCM. When the value of the detected dimming level is higher than the threshold value, for example, in the case of the dimming level corresponding to control point B1, BCM is maintained.

[0055] FIG. 7 shows the switching of the dimming control method when dimming from a low dimming level to a high dimming level. Even if it is detected that the dimming level has been increased from a low dimming level to a high dimming level and the dimming level has exceeded the threshold value, that is, control point D0, unlike the first embodiment, the dimming control switching circuit 36 does not switch the dimming control method and maintains DCM.

[0056] Thereafter, the dimming control switching circuit 36 suppresses the switching of the dimming control method and maintains DCM for a predetermined time after detecting that the dimming level has exceeded the threshold value, regardless of the value of the dimming level. That is, even if the dimming level exceeds the threshold value and shifts to an even higher dimming level, the dimming control method maintains DCM, and the control point shifts from the control point D0 of DCM beyond to control point D1. Even when the dimming level straddles the threshold value, for example, when the dimming level fluctuates between control point D1 and control point D2, it is controlled to maintain DCM. By controlling to maintain DCM for a predetermined time after the dimming level has exceeded the threshold value, regardless of the value of the dimming level, chattering can be suppressed.

[0057] After a predetermined time has elapsed, the dimming control switching circuit 36 detects the dimming level and switches to a control method according to the value of the detected dimming level. Specifically, when the value of the detected dimming level is lower than the threshold value, for example, in the case of the dimming level corresponding to control point D2, DCM is maintained. When the value of the detected dimming level is higher than the threshold value, for example, in the case of the dimming level corresponding to control point D1, the control point is switched to B1 and the dimming control method is switched to BCM.

[0058] As described above, when the dimming level (dimming signal Dim) of the LED lighting device 10 of the second embodiment detects that it has exceeded a predetermined threshold value, and for a predetermined time after detecting that it has exceeded the threshold value, regardless of the value of the dimming level (dimming signal Dim), the switching between the first dimming control circuit 32 and the second dimming control circuit 34 is suppressed. Therefore, similar to the first embodiment, it is possible to suppress chattering when switching the dimming control method.

[0059] The third embodiment will be described with reference to FIG. 8. FIG. 8 is a converter circuit diagram of the third embodiment. In the third embodiment, a buck-boost converter is employed as the converter.

[0060] <Third Embodiment> In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as in the first embodiment, and detailed descriptions thereof are omitted.

[0061] The configuration and function of the control circuit 3 of the buck-boost converter are the same as those of the first and second embodiments, except that a DC voltage having a polarity opposite to that of the DC voltage Vdc is output to the capacitor C2 and the LED light source 2. Detailed descriptions are omitted. Also in this embodiment, the same effects as those of the first embodiment are achieved.

[0062] <Fourth Embodiment> Next, the fourth embodiment of the lighting fixture 100 including the LED lighting device 10 of the first to third embodiments will be described with reference to FIGS. 9 and 10. FIG. 9 is an external view of the lighting fixture of the fourth embodiment. FIG. 10 is an external view of another lighting fixture of the fourth embodiment.

[0063] The lighting fixture 100 shown in FIG. 9 is a downlight, and the lighting fixture 100 shown in FIG. 10 is a spotlight. The lighting fixture 100 includes a circuit box 101, a lamp body 102, and a wiring 103. The circuit box 101 houses the LED lighting device 10. The lamp body 102 houses the LED light source 2. The wiring 103 is electrically connected between the circuit box 101 and the lamp body 102.

[0064] The effects of the fourth embodiment are the same as those of the first to third embodiments. Therefore, in the fourth embodiment, a detailed description of the effects will be omitted.

[0065] The fifth embodiment of the lighting system 200 of the present disclosure will be described with reference to FIG. 11. FIG. 11 is a block diagram of the lighting system of the fifth embodiment.

[0066] <Fifth Embodiment> The lighting system 200 includes an AC power source 6, a plurality of lighting fixtures 100 connected to the AC power source 6, and a dimming controller 4. A dimming signal Dim of the dimming controller 4 is input to each of the lighting fixtures 100. The plurality of lighting fixtures 100 each include the LED lighting device 10 described in the first to third embodiments, and have a function of suppressing chattering when switching the dimming control method. Thereby, chattering when the dimming control method is switched as the dimming level changes is suppressed, and a lighting system with suppressed flickering and the like can be realized.

[0067] Note that the present invention is not limited to the above-described embodiments and their modifications, and it goes without saying that various changes and improvements can be made within the scope of the matters described in the claims of the present application.

Description of Reference Numerals

[0068] 1 Converter, 2 LED light source, 3 Control circuit, 4 Dimming controller, 5 Rectifier circuit, 6 AC power source, 7 Constant current circuit, 10 LED lighting device, 32 First dimming control circuit, 34 Second dimming control circuit, 36 Dimming control switching circuit, 38 Constant current control circuit, 100 Lighting fixture, 101 Circuit box, 102 Lamp body, 103 Wiring, 200 Lighting system

Claims

1. A converter that receives a dimming signal from the outside and supplies an output to an LED light source, A control circuit that controls the output from the converter to the LED light source, An LED lighting device comprising: The control circuit includes: A first dimming control circuit that controls the converter in a first control method, A second dimming control circuit that controls the converter in a second control method, A dimming control switching circuit that switches between the first dimming control circuit and the second dimming control circuit according to the value of the dimming level corresponding to the dimming signal, The dimming control switching circuit has a period during which, regardless of the value of the dimming level, the switching between the first dimming control circuit and the second dimming control circuit is suppressed either before or after detecting that the dimming level has exceeded a predetermined threshold and then switching between the first dimming control circuit and the second dimming control circuit, LED lighting device.

2. The first control method of the first dimming control circuit is the critical current mode (BCM), The second control method of the second dimming control circuit is the discontinuous current mode (DCM), The dimming control switching circuit: In a region where the dimming level is greater than the threshold, controls the converter with the first dimming control circuit, In a region where the dimming level is less than the threshold, controls the converter with the second dimming control circuit. The LED lighting device according to Claim 1.

3. The dimming control switching circuit: (1) Switches between the first dimming control circuit and the second dimming control circuit when it detects that the dimming level has exceeded the threshold, (2) For a predetermined time after switching between the first dimming control circuit and the second dimming control circuit, suppresses the switching between the first dimming control circuit and the second dimming control circuit regardless of the value of the dimming level, (3) After the elapse of the predetermined time, switches to either the first dimming control circuit or the second dimming control circuit according to the value of the dimming level. The LED lighting device according to Claim 2.

4. The dimming control switching circuit: (1) At the time when it detects that the dimming level has exceeded the threshold, and for a predetermined time after detecting that the dimming level has exceeded the threshold, suppresses the switching between the first dimming control circuit and the second dimming control circuit regardless of the value of the dimming level, (2) After the elapse of the predetermined time, switches to either the first dimming control circuit or the second dimming control circuit according to the value of the dimming level. The LED lighting device according to Claim 2.

5. The LED lighting device according to any one of claims 3 or 4, and the LED light source supplied with the output of the converter, comprising: A lighting fixture.

6. Comprising a plurality of lighting fixtures according to claim 5, and a dimming controller for outputting the dimming signal to the plurality of lighting fixtures. A lighting system.

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