LED lighting power supply device and LED lighting device

Abstract

To provide an LED lighting power supply device and an LED lighting device that reduce the risk of LED load failure due to sudden peak currents during switching control and have excellent noise absorption performance even when the terminal voltages of two or more LED loads driven by a switching control are different.SOLUTION: On an output LED lighting power supply device that performs dimming and / or color control by using AC or DC as a power source and switching and driving two or more independent LED loads 15, 16 with different voltages of a load terminal connected to an output smoothing capacitor 14 of one constant current converter 13, a circuit 200 that limits the discharge current flowing through the path from the output smoothing capacitor 14 is installed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power supply device for LED lighting that switches between and drives two or more systems of LED loads, and an LED lighting device in which this power supply device is used. [Background technology]

[0002] 2. Description of the Related Art As an LED lighting device that uses an LED (light emitting diode) as a light source, for example, an LED lighting device that performs color adjustment control by alternately switching and driving two or more systems of LED loads with different color temperatures has been conventionally known (for example, Patent Document 1 and Patent Document 2).

[0003] Incidentally, as a power supply for such an LED lighting device that alternately switches and drives two or more systems of LED loads, a feedback control type power supply is often used to stabilize the current flowing through the LED loads.

[0004] This feedback control type power supply detects the current flowing through the LED load, and when the detected current value decreases, it increases the output of the constant current converter so that the current flowing through the LED load increases, and when the detected current value increases, it decreases the output of the constant current converter so that the current flowing through the LED load decreases. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5141874 [Patent Document 2] JP 2015-95347 A [Patent Document 3] Patent No. 6999100 Summary of the Invention [Problem to be solved by the invention]

[0006] However, such feedback type power supply devices have the following problems. That is, the terminal voltages of two or more systems of LED loads that are switched and driven are generally not the same. For example, when switching the drive from an LED load with a low load terminal voltage to an LED load with a high load terminal voltage, if the difference in the load terminal voltages is large, the current to the LED load with the high load terminal voltage will decrease rapidly immediately after switching. For this reason, feedback is applied and the constant current converter is controlled to increase the output rapidly, which may cause a sudden large current to flow through the LED load and cause it to break down.

[0007] In addition, a relatively large-capacity capacitor is generally connected to the output of a constant current converter in order to supply a stable current to the LED load. However, when the drive is switched from an LED load with a high load terminal voltage to an LED load with a low load terminal voltage, a sudden large current (peak current) flows from the capacitor to the LED load with the low load terminal voltage, and because the capacitance of the capacitor is large, this current continues, which can also cause the LED load to fail.

[0008] As described above, conventional feedback-type power supplies had a problem in that if the terminal voltages of two or more systems of LED loads being switched between, there was a risk of the LED loads breaking down due to a sudden peak current during switching.

[0009] These sudden peak currents flow through the LED load as currents that are difficult to control, resulting in problems such as unstable LED load current.

[0010] Furthermore, in order to solve the problems described above, Patent Document 3 proposes an LED lighting power supply device that uses AC or DC as a power source and performs dimming and / or color adjustment by switching and driving two or more independent LED loads with different load terminal voltages connected to the output of a single constant current converter, in which the constant current converter is controlled by real-time control that turns on the switching element of the constant current converter when the output current of the constant current converter falls below a lower threshold and turns off when it exceeds an upper threshold, and in which the capacitance of the capacitor connected to the output end of the constant current converter is 0.1 μF or less, or no capacitor is provided at the output end of the constant current converter.

[0011] In this case, however, although there is no sudden generation of peak current, the capacitance of the capacitor connected to the output end of the constant current converter is relatively small, which causes a problem in that it is not suitable for absorbing generated noise.

[0012] The present invention has been made in view of the above technical background, and has an object to provide an LED lighting power supply unit and an LED lighting device which reduce the risk of an LED load breaking down due to a sudden peak current during switching drive, even if the terminal voltages of two or more systems of LED loads that are switched drive are different, and which also have excellent performance in absorbing generated noise. [Means for solving the problem]

[0013] The above problems are solved by the following means. (1) A power supply device for LED lighting that uses AC or DC as a power source and performs dimming and / or color adjustment by switching and driving two or more independent LED loads with different load terminal voltages connected to an output smoothing capacitor of a constant current converter, A power supply device for LED lighting that is characterized by having a circuit that limits the current in the path through which the discharge current from the output smoothing capacitor flows. (2) A power supply device for LED lighting as described in the preceding paragraph 1, in which a passive element selected from at least one of a resistor, a thermistor, an inductor, a capacitor, and a constant current diode is used in a circuit that has the effect of limiting the current. (3) The power supply device for LED lighting described in the preceding paragraph 1, in which a constant current circuit is used in the circuit that has the effect of limiting the current. (4) A power supply device for LED lighting as described in the preceding paragraph 1, in which a driving switching element that slows down the ON operation speed to suppress the LED peak current generated when the LED is turned on is used as a driving switching element for switching the LED load in a circuit that has the effect of limiting the current. (5) A power supply device for LED lighting as described in any one of paragraphs 1 to 4 above, in which a circuit having the effect of limiting the current is installed in a path in which the discharge current from the output smoothing capacitor flows in common to two or more independent systems of LED loads. (6) An LED lighting device equipped with the power supply device for LED lighting described in any one of the preceding paragraphs 1 to 4. (7) An LED lighting device as described in paragraph 6 above, in which a circuit with a current limiting effect is installed in a path in which the discharge current from the output smoothing capacitor flows in common to two or more independent LED loads. Effect of the Invention

[0014] According to this invention, in an output LED lighting power supply device that uses AC or DC as a power source and performs dimming and / or color adjustment by switching and driving two or more independent LED loads with different load terminal voltages connected to an output smoothing capacitor of one constant current converter, a circuit that acts to limit the current is mounted on the path through which the discharge current from the output smoothing capacitor flows, so that in a feedback type power supply device, this circuit can suppress the peak current when switching the load, eliminating the risk of the LED load breaking down due to a sudden peak current. Also, in the case of a power supply device using a real-time control method, since there is no delay in control, it is possible to increase the capacity of the capacitor connected to the output end of the constant current converter, eliminating the risk of the LED load breaking down due to a sudden peak current, and reducing noise.

[0015] In other words, regardless of the power supply system used, such as feedback system or real-time control system, it is possible to create a power supply system and LED lighting device that have excellent noise absorption performance while eliminating the risk of LED load failure due to sudden peak current. [Brief description of the drawings]

[0016] [Figure 1] 1 is a circuit diagram of an LED lighting device according to an embodiment of the present invention. [Diagram 2] 2 is a waveform diagram for explaining the operation of a constant current converter in the LED lighting device of FIG. 1. [Diagram 3] 2 is a waveform diagram for explaining the drive switching operation of two systems of LED loads in the LED lighting device of FIG. 1. FIG. [Figure 4] FIG. 11 is a waveform diagram of the current flowing through a first LED load and a second LED load when the load is switched in a case where a passive element is used in a circuit that has the effect of limiting the current. [Diagram 5] FIG. 11 is a circuit diagram showing the mounting position of a circuit that has the effect of limiting a current. [Figure 6] FIG. 11 is another circuit diagram showing the mounting position of a circuit that has the effect of limiting a current. [Figure 7] 1 is a circuit diagram illustrating a case where a constant current circuit is used as a circuit having a current limiting effect. [Figure 8] FIG. 11 is a waveform diagram of the current flowing through a first LED load and a second LED load when the load is switched in a case where a circuit that has the effect of limiting the current using a constant current circuit is installed. [Figure 9] FIG. 11 is a circuit diagram showing yet another example of a circuit having a current limiting effect. [Figure 10] 10 is a waveform diagram of currents flowing through a first LED load and a second LED load when the load is switched in a case where the circuit having the effect of limiting the current in FIG. 9 is mounted. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] FIG. 1 is a circuit diagram showing the configuration of an LED lighting device 1 equipped with an LED power supply device according to an embodiment of the present invention. This LED lighting device 1 includes a rectifier circuit 11, a smoothing capacitor 12 connected to the output of the rectifier circuit 11, a constant current converter 13 connected to the output of the smoothing capacitor 12, a capacitor (corresponding to an output smoothing capacitor) 14 connected to the output end of the constant current converter 13, two systems of first and second LED loads 15 and 16, two load switching units 17 and 18, and a load switching / dimming control unit 19. Furthermore, a circuit 200 that acts to limit the current is connected between the connection point between the positive terminal of the capacitor 14 and the output of the constant current converter 13 and the input terminals of the first and second LED loads 15 and 16. In the following description, the circuit 200 that acts to limit the current is also called a current limiting circuit 200.

[0019] The rectifier circuit 11 is a circuit that performs full-wave rectification on the AC input from the AC power source 2, and the smoothing circuit 12 serves to smooth the input voltage after full-wave rectification by the rectifier circuit 11.

[0020] The constant current converter 13 is a converter that operates to output a constant current, and in this embodiment specifically includes a real-time control unit 131, a switching element 132 consisting of a MOSFET whose drain terminal is connected to the positive terminal of the smoothing capacitor 12, a resistor 133 whose one end is connected to the source terminal of the switching element 132, an impedance element 134 connected to the other end of the resistor 133, and a diode 135 connected between the negative terminal of the smoothing capacitor 12 and the source terminal of the switching element 132 with its cathode side facing the source terminal of the switching element 132.

[0021] A gate signal is input from the real-time control unit 131 to the gate of the switching element 132 . When this gate signal is input, the switching element 132 turns on and the power charged in the smoothing capacitor 12 is supplied to the output side of the switching element 132 .

[0022] Resistor 133 detects the output current of constant current converter 13. In other words, real-time control unit 131 constantly monitors the voltage across resistor 133, which is determined by the output current value and the resistance value, and when this monitored voltage falls below a lower threshold, real-time control unit 131 outputs a gate signal to switching element 132, turning on switching element 132. When the monitored voltage exceeds an upper threshold, the gate signal from real-time control unit 131 to switching element 132 disappears, turning off switching element 132. In other words, real-time control is performed.

[0023] The on / off timing and frequency of the switching element 132 by the real time control unit 131 are also controlled by a dimming signal from the load switching and dimming control unit 19. In other words, when adjusting the light intensity (brightness) of the first and second LED loads 15, 16, the load switching and dimming control unit 19 sends a dimming signal according to an instruction from the user to the real time control unit 131, and the real time control unit 131 controls the on / off of the switching element 132 according to this dimming signal, and further adjusts the light intensity of the LED loads 15, 16 by changing the upper limit threshold value and the lower limit threshold value that are compared with the voltage across the resistor 133, if necessary.

[0024] The impedance element 134 stabilizes the current output from the constant current converter 13 and supplied to the LED loads 15 and 16. The diode 135 is an element for forming a discharge circuit for the energy held by the impedance element 134 when the switching element 132 is off.

[0025] Capacitor 14 connected to the output end of constant current converter 13 serves to suppress and smooth the pulsation of the output current of constant current converter 13 and to supply a stable current to LED loads 15 and 16 .

[0026] The first and second LED loads 15, 16 are both connected in parallel to the capacitor 14. These LED loads 15, 16 have different color temperatures and each is composed of one LED or a series connection of multiple LEDs. The load terminal voltages of the LED loads 15, 16 are different due to the number of LEDs included in each load, variations in characteristics, etc., and in this embodiment, the load terminal voltage of the first LED load 15 is higher than the load terminal voltage of the second LED load 16.

[0027] The first load switching unit 17 and the second load switching unit 18 are each composed of a switching element such as a MOSFET, the first load switching unit 17 being connected between the cathode side of the first LED load 15 and the negative terminal of the capacitor 14, and the second load switching unit 18 being connected between the cathode side of the second LED load 16 and the negative terminal of the capacitor 14. Therefore, when the load switching units 17 and 18 are turned on, the circuits of the LED loads 15 and 16 are closed and a current flows through the LED loads 15 and 16, causing the LED loads 15 and 16 to emit light. Conversely, when the load switching units 17 and 18 are turned off, the LED loads 15 and 16 are opened and no current flows through the LED loads 15 and 16.

[0028] The on / off of each of the load switching units 17, 18 is controlled by a gate signal, which is a drive switching signal, from the load switching / dimming control unit 19. In this embodiment, the load switching / dimming control unit 19 alternately outputs drive switching signals to each of the load switching units 17, 18, thereby alternately switching and driving the first and second LED loads 15, 16. Also, by adjusting the on time (duty ratio) of each of the load switching units 17, 18, the light emission time of each of the LED loads 15, 16 can be changed, allowing color adjustment.

[0029] As described above, the load switching / dimming control unit 19 performs dimming control by outputting a dimming signal to the real time control unit 131, and also performs light emission / color adjustment control by outputting a drive switching signal to each of the load switching units 17, 18. The dimming / color adjustment settings and changes are made based on instructions from the user. The user operates a dial knob, a remote control, etc. to give instructions to the load switching / dimming control unit 19 to set or change the dimming / color adjustment.

[0030] Next, a basic operation of the LED lighting device 1 shown in FIG. 1 will be described.

[0031] As shown in FIG. 2B, when the switching element 132 is turned on at timing T1 by the gate signal from the real-time control unit 131, a current A flows from the smoothing capacitor 12 to the load side via the switching element 132, the resistor 133, and the impedance element 134. The current A gradually increases linearly as shown in FIG. 2A. The increase in the current A increases the voltage difference between both ends of the resistor 133, and when the voltage difference reaches the upper threshold, the real-time control unit 131 turns off the switching element 132 at timing T2 as shown in FIG. 2B. Then, the current A gradually decreases linearly as shown in FIG. 2A. The decrease in the current A reduces the voltage difference between both ends of the resistor 133, and when the voltage difference reaches the lower threshold, the real-time control unit 131 turns on the switching element 132 again at timing T3. Then, the current A starts to rise again, and this process is repeated thereafter. 2A, the current A repeatedly increases and decreases in a triangular wave shape between a lower limit value A1 and an upper limit value A2 as the switching element 132 is turned on and off. The frequency at which the current A increases and decreases (the on / off frequency of the switching element 132) is preferably set to several tens of kHz to several hundreds of kHz.

[0032] 3(C)(D), the first load switching unit 17 is turned on and the second load switching unit 18 is turned off at timing T5, and the first load switching unit 17 is turned off and the second load switching unit 18 is turned on at timing T6, and thereafter, this switching is repeated as shown at timings T7 to T9. The switching frequency is set to about 1 kHz.

[0033] 3(A) and 3(B), when the first load switching unit 17 is turned on and the second load switching unit 18 is turned off, the load current 1 flows through the first LED load 15 and the load current 2 flowing through the second LED load 16 becomes zero. When the first load switching unit 17 is switched off and the second load switching unit 18 is switched on, the load current 1 flowing through the first LED load 15 becomes zero and the load current 2 flows through the second LED load 16.

[0034] In this embodiment, as described above, the load terminal voltage of the first LED load 15 is greater than the load terminal voltage of the second LED load 16. Therefore, when the first load switching unit 17 switches from on to off and the second load switching unit 18 switches from off to on, and the load switches from the first LED load 15 to the second LED load 16, the terminal voltage of the load drops suddenly. Due to this difference in terminal voltage, the charge of the capacitor 14 flows suddenly to the second LED load 16. If the capacity of the capacitor 14 is large, a sudden peak current flows to the second LED load 16, leading to a failure of the second LED load 16. If the capacity of the capacitor 14 is reduced, the magnitude of the peak current can also be reduced, but the absorption performance of noise generated in the circuit decreases.

[0035] In this embodiment, in order to reduce the peak value of the peak current that suddenly flows from the capacitor 14 to the second LED load 16 when the load is switched from the first LED load 15 to the second LED load 16, as described above, a current limiting circuit 200 is installed between the connection point between the positive terminal of the capacitor 14 and the output of the constant current converter 13, and the input terminals of the first and second LED loads 15 and 16.

[0036] The current limiting circuit 200 may include passive elements such as at least one of a resistor, a thermistor, an inductor, a capacitor, and a constant current diode.

[0037] FIG. 4 is a waveform diagram showing the current flowing through the first LED load 15 and the second LED load 16 when the load is switched in the case where the current limiting circuit 200 using a passive element is connected.

[0038] FIG. 4A shows a load current 1 flowing through a first LED load 15, and FIG. 4B shows a load current 2 flowing through a second LED load 16.

[0039] At timing T10, the load is switched from the first LED load 15 to the second LED load 16. The current 1 of the first LED load 15 becomes zero at timing T10. Meanwhile, the current flows from the capacitor 14 to the second LED load 16, but since the terminal voltage of the second LED load 16 is smaller than that of the first LED load 15, if the current limiting circuit 200 is not connected, a large peak current will flow as shown by the dashed line I1 in FIG.

[0040] However, since the current limiting circuit 200 is actually connected, the current flowing from the capacitor 14 to the second LED load 16 is in a state where the peak value of the peak current I1 is suppressed as shown by the solid line I2. After that, the peak current decreases and settles at the current value I3 of the constant current converter 13.

[0041] In this way, the peak value of the peak current I1 flowing through the second LED load 16 during load switching can be suppressed by the current limiting circuit 200, which can prevent the second LED load 16 from breaking down due to an unexpected peak current or reduce instability in the operation of the second LED load 16. Moreover, since the peak value of the peak current I1 can be suppressed regardless of the capacitance of the capacitor 14, a capacitor with a large capacitance can be used for the capacitor 14, which provides excellent noise absorption performance in the circuit.

[0042] The mounting position of the current limiting circuit 200 is not limited to that shown in FIG. 1, and it may be interposed in the path through which the discharge current from the capacitor 14 flows. For example, as shown in FIG. 5, it may be the position B1 shown in FIG. 1, it may be the position A1 between the positive terminal of the capacitor 14 and the output of the constant current converter 13, or it may be the position C1 between the output of the first load switching unit 17, the second load switching unit 18 and the negative terminal of the capacitor 14. Alternatively, it may be the position D1 between the output of the second LED load 16 and the second load switching unit 18. In short, it is sufficient that it is a position on the path through which the discharge current from the capacitor 14 flows to the second LED load 16 and returns to the capacitor 14. In addition, the current limiting circuit 200 may be mounted in one place, or may be mounted in combination at two or more positions.

[0043] In addition, when the current limiting circuit 200 is mounted only at the position D1 between the output of the second LED load 16 and the second load switching unit 18, it is also preferable to mount it at the position E1 between the output of the first LED load 15 and the first load switching unit 17. The reason for this is to prevent a sudden peak current from flowing through the first LED load 15 when the first LED load 15 is switched on, which may cause a breakdown or the like, if the terminal voltage of the first LED load 15 becomes smaller due to a breakdown or the like of the second LED load 16. Of course, the current limiting circuit 200 may be mounted at the position E1 in combination with the current limiting circuit 200 at least at any of the positions A1 to D1.

[0044] However, it is desirable to have the discharge current from the capacitor 14 intervene at least at one of positions A1 to C1, which are positions on a path through which the discharge current flows in common regardless of whether the discharge current is switched to the independent first LED load 15 or the second LED load 16, in order to obtain a peak current suppression effect for both the first LED load 15 and the second LED load 16 by one current limiting circuit 200.

[0045] 5 is a circuit in which the input sides of the first LED load 15 and the second LED load 16 are at a common potential (common) on the high side, but as shown in Fig. 6, the first LED load 15 and the second LED load 16 may be connected to the output sides of the first load switching unit 17 and the second load switching unit 18, respectively, and the output sides of the first LED load 15 and the second LED load 16 may be at a common potential (common) on the low side. In this case, the mounting position of the current limiting circuit 200 may be the same as in Fig. 5, as long as it is interposed in the path through which the discharge current from the capacitor flows to the second LED load 16.

[0046] For example, like the position B1 shown in FIG. 1 and FIG. 5, it may be a position B2 between the connection point between the positive terminal of the capacitor 14 and the output of the constant current converter 13 and the input terminals of the first and second LED loads 15 and 16, or it may be a position A2 between the negative terminal of the capacitor 14 and the low-side common potential line. Alternatively, it may be a position C2 between the connection point between the negative terminal of the capacitor 14 and the low-side common potential line and the outputs of the first LED load 15 and the second LED load 16. Furthermore, it may be a position D2 between the second load switching unit 18 and the second LED load 16. In short, it is sufficient that it is a position on the path where the discharge current from the capacitor 14 flows to the second LED load 16 and returns to the capacitor 14. Also, like the case of FIG. 5, the current limiting circuit 200 may be mounted in one place, or may be mounted in combination at two or more places.

[0047] Furthermore, when the current limiting circuit 200 is mounted only at position D2 between the second load switching unit 18 and the second LED load 16, it is preferable to also mount it at position E2 between the first load switching unit 17 and the first LED load 15 for the same reason as in the case of Fig. 5. Of course, the current limiting circuit 200 may be mounted at position E2 in combination with the current limiting circuit 200 at least at any one of positions A2 to D2.

[0048] However, it is desirable to have the discharge current from the capacitor 14 located at positions A2 to C2, which are positions on a path through which the discharge current flows in common regardless of whether the discharge current is switched to the independent first LED load 15 or the second LED load 16, in order to obtain a peak current suppression effect for both the first LED load 15 and the second LED load 16 by one current limiting circuit 200.

[0049] 1, a passive element is used as the current limiting circuit 200, but if a resistor or a power thermistor is used as the passive element, there is always a loss, which may reduce efficiency. Also, if an inductor or a capacitor is used, the peak current value varies depending on the frequency of the peak current, which may make it difficult to manage.

[0050] Therefore, although the number of parts increases, it is desirable to use a constant current circuit as the current limiting circuit 200, which can avoid the decrease in efficiency and the fluctuation in the peak current value.

[0051] A specific example of a constant current circuit is shown in Fig. 7. The constant current circuit shown in Fig. 7 includes a switching element 201 made of a MOSFET, a resistor 202 connected in series to the source of the switching element 201, and an operational amplifier 203. The source of the switching element 201 is connected to the inverting input terminal of the operational amplifier 203, a reference voltage 204 is connected to the non-inverting input terminal, and an output terminal of the operational amplifier 203 is connected to the gate of the switching element 201.

[0052] In this constant current circuit, the gate voltage of switching element 201 connected to the output of operational amplifier 203 is controlled to be constant, so that the current flowing between the drain and source of the switching element is also constant.

[0053] The constant current circuit is not limited to the configuration shown in FIG. 7, and any other configuration may be adopted.

[0054] FIG. 8 is a waveform diagram showing the current flowing through the first LED load 15 and the second LED load 16 when the load is switched in the case where the current limiting circuit 200 using a constant current circuit is connected.

[0055] 8A shows a load current 1 flowing through a first LED load 15, and FIG. 8B shows a load current 2 flowing through a second LED load 16. As shown in FIG.

[0056] At timing T10, the load is switched from the first LED load 15 to the second LED load 16. The current 1 of the first LED load 15 becomes zero at timing T10. Meanwhile, the current flows from the capacitor 14 to the second LED load 16, but since the terminal voltage of the second LED load 16 is smaller than that of the first LED load 15, if the current limiting circuit 200 is not connected, a large peak current will flow as shown by the dashed line I1 in FIG.

[0057] However, in reality, the current limiting circuit 200 using a constant current circuit is connected, so the current flowing from the capacitor 14 to the second LED load 16 becomes a constant current with the peak value of the peak current suppressed as shown by the solid line I2. After that, the current value of the constant current converter 13 settles to I3.

[0058] In this way, the current limiting circuit 200 using the constant current circuit can suppress the peak value of the peak current flowing through the second LED load 16 when the load is switched, thereby preventing the second LED load 16 from breaking down due to an unexpected peak current, or reducing the instability of the operation of the second LED load 16. Furthermore, the loss that occurs when using a passive element is reduced, and the fluctuation of the peak current is also reduced. Furthermore, since the peak value of the peak current can be suppressed regardless of the capacity of the capacitor 14, a capacitor with a large capacity can be used as the capacitor 14, and the circuit has excellent noise absorption performance.

[0059] Next, another embodiment of the current limiting circuit 200 will be described with reference to Fig. 9. In this embodiment, a MOSFET serving as a driving switching element constituting the second load switching unit 18 connected in series with the second LED load 16 is used as a switching element having the effect of slowing down the ON operation speed and suppressing the peak current of the second LED load 16 generated when the load is ON.

[0060] 9, two resistors 181 and 182 are connected in series to the gate of the second load switching unit 18, and a diode 183 is connected in parallel to the resistor 181. The anode of the diode 183 is connected to the connection point of the resistors 181 and 182. In addition, a parasitic capacitance 184 exists between the gate and source of the second load switching unit 18.

[0061] When switching from the first LED load 15 to the second LED load 16, the second load switching unit 18 in Fig. 9 is applied with a pulsed gate signal, which is a drive signal as shown in Fig. 10(C). Resistors 181 and 182 are connected to the gate of the second load switching unit 18, and a parasitic capacitance 184 exists between the gate and source. If the resistance values ​​of the resistors 181 and 182 are Ra and Rb, respectively, and the value of the parasitic capacitance 184 is Ca, the gate signal rises with a time constant of (Ra+Rb) x Ca. In this way, the gate signal is rounded when the second load switching unit 18 is on, so that the speed at which the second load switching unit 18 is turned on is slowed down. As shown in Fig. 10(B) showing the waveform of the load current 2 flowing through the second LED load 16, the load current 2 starts to flow gradually when turned on (solid line I2), and then settles to the current value I3 of the constant current converter 13. This makes it possible to suppress the peak current (dashed line I1) of the second LED load 16 that occurs when the second LED load 16 is on.

[0062] Furthermore, when the second load switching unit 18 is off, discharge occurs with a time constant of Rb×Ca. However, by setting Ra>>Rb, the gate signal can be made dull only when the second load switching unit 18 is on.

[0063] In addition, regarding the second load switching unit 18 as a driving switching element, the configuration having the effect of slowing down the ON operation speed and suppressing the LED peak current generated when the element is ON is not limited to that shown in FIG. 9, and any other configuration may be adopted.

[0064] In addition, when a switching element having the effect of slowing down the ON operation speed to suppress the peak current of the second LED load 16 generated when the load is turned on is used for the second load switching unit 18, a switching element having the effect of slowing down the ON operation speed to suppress the peak current of the second LED load 16 generated when the load is turned on may be used for the first load switching unit 17 as well.

[0065] Also, it may be combined with other current limiting circuits 200 arranged at positions A1 to E1 and A2 to E2 shown in FIGS.

[0066] In this way, the peak current of the second LED load 16 generated when the second load switching unit 18 is turned on can be suppressed by slowing down the speed of the turn-on operation of the second load switching unit 18, thereby preventing the second LED load 16 from breaking down due to an unexpected peak current, or reducing instability in the operation of the second LED load 16. Moreover, since the peak value of the peak current can be suppressed regardless of the capacitance of the capacitor 14, a capacitor with a large capacity can be used, resulting in excellent noise absorption performance in the circuit.

[0067] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, the power source of the LED lighting power supply device 1 has been described as an AC power supply 2, but the power supply device may obtain a constant current from a DC power supply and supply it to the first and second LED loads 15 and 16.

[0068] Also, although the LED loads having different load voltages are two systems, the first and second LED loads 15 and 16, three or more systems may be used.

[0069] Also, while the LED power supply device is described as being of the real-time control type, it may be of the feedback type or other type. Regardless of the type of power supply device, it is possible to obtain a power supply device and LED lighting device that have excellent noise absorption performance while eliminating the risk of LED load failure due to sudden peak current. [Explanation of symbols]

[0070] 1 LED lighting device 2 AC power supply 11 Rectifier circuit 12 Smoothing capacitor 13 Constant current converter 131 Real-time control section 132 Switching element 133 Resistance 134 Impedance Element 135 Diode 14 Capacitor 15 First LED Load 16 Second LED Load 17 First load switching section 18 Second load switching section 19 Load switching and dimming control unit 181, 182, 202 Resistance 183 Diode 200 Current limiting circuit (a circuit that limits the current) 201 Switching element 203 Operational Amplifier 204 Reference Voltage

Claims

1. A power supply device for LED lighting that uses AC or DC as a power source and performs dimming and / or color adjustment by switching and driving two or more independent systems of LED loads with different load terminal voltages connected to an output smoothing capacitor of one constant current converter, A power supply device for LED lighting, characterized in that it is equipped with a circuit that has the effect of limiting the current in the path through which the discharge current from the output smoothing capacitor flows.

2. 2. The power supply device for LED lighting according to claim 1, wherein a passive element selected from at least one of a resistor, a thermistor, an inductor, a capacitor, and a constant current diode is used in a circuit that acts to limit a current.

3. 2. The power supply device for LED lighting according to claim 1, wherein a constant current circuit is used as the circuit having the effect of limiting the current.

4. 2. The power supply device for LED lighting as claimed in claim 1, wherein a driving switching element having the effect of slowing down the ON operation speed to suppress the LED peak current generated when the LED is turned on is used as a driving switching element for switching the LED load in a circuit having a current limiting effect.

5. 5. The power supply device for LED lighting according to claim 1, wherein the circuit having the effect of limiting the current is mounted on a path through which a discharge current from an output smoothing capacitor flows in common to two or more independent systems of LED loads.

6. An LED lighting device comprising the power supply device for LED lighting according to any one of claims 1 to 4.

7. 7. The LED lighting device according to claim 6, wherein the circuit having the effect of limiting the current is mounted on a path through which a discharge current from the output smoothing capacitor flows in common to two or more independent systems of LED loads.

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