DC power supply device, lighting fixture and lighting system

Abstract

To provide a DC power supply device which has a high power factor even in a case where a drive circuit in a part included in a plurality of drive circuits is caused to output drive power, a lighting fixture and a lighting system.SOLUTION: A DC power supply device comprises: a rectifier which rectifies an alternating current and includes an output end which outputs an output current; a circuit ground; a plurality of input capacitors which is electrically connected in parallel between the output end and the circuit ground and to which a plurality of input current obtained by splitting the output current is inputted respectively; a plurality of branch current paths in which the plurality of input currents flows respectively; a plurality of power factor enhancement circuits electrically connected to the plurality of the input capacitors; a plurality of drive circuits electrically connected to the plurality of power factor enhancement circuits and outputting a plurality of pieces of drive power; and an element which blocks flow of a current to a branch current path included in the plurality of branch current paths in a direction opposite to a direction of the input current flowing in the branch current path.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a DC power supply device, a lighting fixture, and a lighting system.

Background Art

[0002] Patent Document 1 discloses an LED drive. The LED drive includes a bridge rectifier, a valley fill circuit, and a current drive circuit. The valley fill circuit improves the power factor of the entire LED drive (paragraph 0011).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a demand for including a plurality of current drive circuits in an LED drive that can drive a plurality of LEDs respectively, and driving an LED with a part of the plurality of current drive circuits. However, in such a case, a circuit that can improve the power factor of the entire LED drive has not been clarified.

[0005] One aspect of the present disclosure has been made in view of this problem. One aspect of the present disclosure aims to provide a DC power supply device, a lighting fixture, and a lighting system that have a high power factor even when driving power is output to a part of a plurality of drive circuits included in the plurality of drive circuits.

Means for Solving the Problems

[0006] The DC power supply device according to the first aspect of the present disclosure includes a rectifier that rectifies alternating current and has an output terminal for outputting an output current, a circuit ground, a plurality of input capacitors that are electrically connected in parallel between the output terminal and the circuit ground and into which a plurality of input currents obtained by shunting the output current are respectively input, a plurality of branch current paths through which the plurality of input currents respectively flow, a plurality of power factor improvement circuits that are electrically connected to the plurality of input capacitors respectively, a plurality of drive circuits that are electrically connected to the plurality of power factor improvement circuits respectively and output a plurality of drive powers respectively, and an element that is included in the branch current path included in the plurality of branch current paths and blocks current from flowing in a direction opposite to the direction of the input current flowing through the branch current path.

[0007] The lighting fixture according to the second aspect of the present disclosure includes the DC power supply device according to the first aspect of the present disclosure, a light source that is driven by a first drive power included in the plurality of drive powers, and a connection portion that can connect to another lighting fixture and outputs a second drive power different from the first drive power included in the plurality of drive powers to the other lighting fixture when the other lighting fixture is connected.

[0008] The lighting system according to the third aspect of the present disclosure includes the lighting fixture according to the second aspect of the present disclosure and the other lighting fixture. The other lighting fixture is connected to the connection portion and includes another light source that is driven by the second drive power.

[0009] The lighting fixture according to the fourth aspect of the present disclosure includes the DC power supply device according to the first aspect of the present disclosure and a connection portion that can connect a light source and outputs at least one drive power included in the plurality of drive powers to the light source when the light source is connected, and changes the at least one drive power according to the light source.

[0010] The lighting system according to the fifth aspect of the present disclosure includes the lighting fixture according to the fourth aspect of the present disclosure and the light source.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Regarding the drawings, the same or equivalent elements are denoted by the same reference numerals, and duplicate descriptions are omitted.

[0013] 1 First Embodiment 1.1 Lighting Device FIG. 1 is a block diagram of a lighting device including a DC power supply device according to a first embodiment and a plurality of light sources connected to the DC power supply device.

[0014] AC power P10 is input to the DC power supply device 1 shown in FIG. 1. The DC power supply device 1 generates a plurality of driving powers P31 and P32 from the input AC power P10. The generated driving powers P31 and P32 are DC powers. The DC power supply device 1 outputs the generated driving powers P31 and P32.

[0015] The plurality of driving powers P31 and P32 output are respectively input to the plurality of light sources 11 and 12. The light sources 11 and 12 are respectively driven by the input driving powers P31 and P32. The light sources 11 and 12 respectively emit lights L11 and L12 corresponding to the driving powers P31 and P32.

[0016] Each light source 10 included in the light sources 11 and 12 includes a light-emitting diode (LED) lamp. The LED lamp includes a plurality of LEDs. The plurality of LEDs are electrically connected in series. Each light source 10 may include a plurality of LED lamps. The plurality of LED lamps are electrically connected in parallel. Each light source 10 may include a light emitter other than an LED lamp. For example, each light source 10 may include an incandescent bulb or the like.

[0017] The DC power supply device 1 is a two-output type DC power supply device. Therefore, up to two light sources 11 and 12 can be connected to the DC power supply device 1. Also, the DC power supply device 1 can output up to two driving powers P31 and P32. The DC power supply device 1 may be a multi-output type DC power supply device of three-output type or more. Therefore, three or more light sources may be connected to the DC power supply device 1. Also, the DC power supply device 1 may be able to output three or more driving powers.

[0018] 1.2 DC Power Supply Device As shown in FIG. 1, the DC power supply device 1 includes a circuit ground 100, an input section 110, a rectifier 120, a plurality of input capacitors 131 and 132, a plurality of power factor correction (PFC) circuits 141 and 142, a plurality of drive circuits 151 and 152, a plurality of output sections 161 and 162, and a plurality of elements 171 and 172.

[0019] 1.3 Input Section As shown in FIG. 1, the input section 110 includes terminals 110a and 110b.

[0020] The terminal 110a of the input section 110 is electrically connected to the first pole of the AC power supply. The terminal 110b of the input section 110 is electrically connected to the second pole of the AC power supply. Thereby, the AC power P10 output by the AC power supply is input between the terminal 110a and the terminal 110b.

[0021] The connected AC power supply is a commercial power supply or a transformer circuit electrically connected to the commercial power supply. The connected AC power supply may be a power supply other than the commercial power supply and the transformer circuit.

[0022] The terminal 110b of the input section 110 is electrically connected to a terminal having the same potential as the ground. Thereby, the same potential as the ground is given to the terminal 110b. Also, an AC potential corresponding to the input AC power P10 is given to the terminal 110a of the input section 110. Thereby, the terminal 110a outputs an output current C110 that is AC corresponding to the input AC power P10.

[0023] 1.4 Rectifier As shown in FIG. 1, the rectifier 120 includes an input terminal 120a, an input terminal 120b, an output terminal 120c, and an output terminal 120d. The rectifier 120 rectifies the alternating current input between the input terminal 120a and the input terminal 120b and outputs a pulsating current from between the output terminal 120c and the output terminal 120d.

[0024] The input terminal 120a of the rectifier 120 is electrically connected to the terminal 110a of the input section 110. The input terminal 120b of the rectifier 120 is electrically connected to the terminal 110b of the input section 110. Thereby, an alternating current is input between the input terminal 120a and the input terminal 120b. Also, a pulsating current is output from between the output terminal 120c and the output terminal 120d of the rectifier 120.

[0025] The output terminal 120d of the rectifier 120 is electrically connected to the circuit ground 100. Thereby, a ground potential is applied to the output terminal 120d. Also, a pulsating current potential is applied to the output terminal 120c of the rectifier 120. Thereby, the output terminal 120c outputs an output current C120 that is a pulsating current.

[0026] The rectifier 120 is a full-wave rectifier circuit. The full-wave rectifier circuit is a bridge rectifier circuit, a full-wave voltage-doubling rectifier circuit, or the like. The rectifier 120 may be a half-wave rectifier circuit. The rectifying element provided in the rectifier 120 is a diode. The rectifying element may be an element other than a diode.

[0027] 1.5 Input Capacitor As shown in FIG. 1, each input capacitor 130 included in the input capacitors 131 and 132 includes terminals 130a and 130b. Each input capacitor 130 smoothes the pulsating current input between the terminals 130a and 130b and outputs a pulsating current that is made closer to a smoothed direct current from between the terminals 130a and 130b.

[0028] The terminals 130a of the input capacitors 131 and 132 are electrically connected to the output terminal 120c of the rectifier 120. The terminals 130b of the input capacitors 131 and 132 are electrically connected to the circuit ground 100 and are electrically connected to the output terminal 120d of the rectifier 120 via the circuit ground 100. Thus, a pulsating current is input between the terminal 130a and the terminal 130b. Also, a pulsating current that has been smoothed and brought closer to direct current is output from between the terminal 130a and the terminal 130b. Further, the input capacitors 131 and 132 are electrically connected in parallel between the output terminal 120c and the circuit ground 100.

[0029] 1.6 Current Path and Branch Current Paths As shown in FIG. 1, the DC power supply device 1 includes a current path 1000 and a plurality of branch current paths 1011 and 1012.

[0030] One end of the current path 1000 is electrically connected to the output terminal 120c of the rectifier 120. One ends of the branch current paths 1011 and 1012 are electrically connected to the other end of the current path 1000. Thereby, one ends of the branch current paths 1011 and 1012 are electrically connected to the output terminal 120c of the rectifier 120 via the current path 1000. Also, the branch current paths 1011 and 1012 branch from a branch point at the other end of the current path 1000. The other ends of the branch current paths 1011 and 1012 are electrically connected to the terminals 130a of the input capacitors 131 and 132, respectively. Thereby, an output current C120 flows through the current path 1000. Also, a plurality of input currents C131 and C132 obtained by shunting the output current C120 flow through the plurality of branch current paths 1011 and 1012, respectively. Also, the input currents C131 and C132 are input to the input capacitors 131 and 132, respectively. Thereby, the input capacitors 131 and 132 smooth the input currents C131 and C132 and output smoothed input currents C141 and C142, respectively. The current path 1000 may be omitted. When the current path 1000 is omitted, one ends of the branch current paths 1011 and 1012 are directly connected to the output terminal 120c of the rectifier 120. When there are three or more branch current paths, not all of the three or more branch current paths have to branch from the same branch point.

[0031] 1.7 PFC Circuit As shown in FIG. 1, the PFC circuits 141 and 142 are electrically connected to the input capacitors 131 and 132, respectively. Thereby, smoothed input currents C141 and C142 are input to the PFC circuits 141 and 142, respectively. The PFC circuits 141 and 142 output output powers P21 and P22, respectively.

[0032] Each PFC circuit 140 included in the PFC circuits 141 and 142 reduces the phase difference between the input voltage and the input current. Each PFC circuit 140 suppresses harmonics generated by the connected input capacitor 130. Thereby, each PFC circuit 140 improves the power factor of the DC power supply device 1 and makes the power factor approach 1.

[0033] The improvement of the power factor of the DC power supply device 1 by each PFC circuit 140 is affected by the input power input to each PFC circuit 140 and the capacitance of the input capacitor to which each PFC circuit 140 is connected. Therefore, each PFC circuit 140 is designed so that it can effectively improve the power factor of the DC power supply device 1 according to the relationship between the input power and the capacitance of the input capacitor. The DC power supply device 1 is configured such that this relationship does not change significantly in any of the cases where the light sources 11 and 12 are respectively connected to the drive circuits 151 and 152, where the light source 11 is connected to the drive circuit 151 but the light source is not connected to the drive circuit 152, and where the light source 12 is connected to the drive circuit 152 but the light source is not connected to the drive circuit 151. Thereby, the DC power supply device 1 has a high power factor in any case.

[0034] Each PFC circuit 140 may be a PFC circuit of any of a passive method, a partial switching method, and an active method.

[0035] The PFC circuits 141 and 142 may be respectively built in the drive circuits 151 and 152.

[0036] 1.8 Drive Circuit As shown in FIG. 1, the drive circuits 151 and 152 are electrically connected to the PFC circuits 141 and 142, respectively. Thereby, the output power P21 and P22 output are respectively input to the drive circuits 151 and 152. The drive circuits 151 and 152 respectively generate drive power P31 and P32 from the input output power P21 and P22. The drive circuits 151 and 152 respectively output the generated drive power P31 and P32.

[0037] Light sources 11 and 12 are electrically connected to drive circuits 151 and 152, respectively. The drive circuits 151 and 152 output drive powers P31 and P32 to the connected light sources 11 and 12, respectively, to drive the light sources 11 and 12. The drive circuits 151 and 152 perform dimming of the light sources 11 and 12 by analog control, pulse width modulation (PWM) control, etc., respectively.

[0038] 1.9 Element As shown in FIG. 1, each element 170 included in elements 171 and 172 includes a first terminal 170a and a second terminal 170b. Each element 170 permits current to flow from the first terminal 170a to the second terminal 170b and blocks current from flowing from the second terminal 170b to the first terminal 170a.

[0039] The first terminals 170a of elements 171 and 172 are electrically connected to the output terminal 120c of the rectifier 120. The second terminals 170b of elements 171 and 172 are electrically connected to the terminals 130a of the input capacitors 131 and 132, respectively. Elements 171 and 172 are inserted into branch current paths 1011 and 1012, respectively. The second terminal 170b of each element 170 is electrically connected to the terminal 130a of the input capacitor 130 into which the input current C130 flowing through the inserted branch current path 1010 is input. Thereby, elements 171 and 172 permit input currents C131 and C132 to flow through branch current paths 1011 and 1012. Also, elements 171 and 172 block currents C151 and C152 flowing in directions opposite to the directions of input currents C131 and C132 from flowing through branch current paths 1011 and 1012, respectively.

[0040] In the first embodiment, each element 170 is a diode 180. The diode 180 includes an anode 180a and a cathode 180b. The first terminal 170a of each element 170 is the anode 180a. The second terminal 170b of each element 170 is the cathode 180b.

[0041] Diode 180 permits current to flow from anode 180a to cathode 180b and blocks current from flowing from cathode 180b to anode 180a.

[0042] 1.10 Operation As shown in FIG. 1, when light sources 11 and 12 are respectively connected to drive circuits 151 and 152, drive circuits 151 and 152 output drive powers P31 and P32 to light sources 11 and 12, respectively. For this reason, forward biases are applied to elements 171 and 172. As a result, elements 171 and 172 turn on. As a result, input currents C131 and C132 flow through branch current paths 1011 and 1012, respectively.

[0043] In the state shown in FIG. 1, input powers necessary to drive light sources 11 and 12 are respectively input to PFC circuits 141 and 142. That is, an input power P necessary to drive one light source 10 is input to one PFC circuit 140. Further, PFC circuits 141 and 142 are respectively connected to input capacitors 131 and 132. For this reason, one PFC circuit 140 shares one input capacitor 130. For this reason, one PFC circuit 140 is designed so as to be able to effectively improve the power factor of DC power supply device 1 according to the relationship between the input power P necessary to drive one light source 10 and the capacitance C of the one input capacitor 130 to be shared.

[0044] FIG. 2 is a block diagram of an illumination device including the DC power supply device of the first embodiment and one light source connected to the DC power supply device.

[0045] As shown in FIG. 2, when the light source 11 is connected to the drive circuit 151 but not to the drive circuit 152, the drive circuit 151 outputs drive power P31 to the light source 11, while the drive circuit 152 does not output drive power to the light source. As a result, a forward bias is applied to the element 171, but after the input capacitor 132 is charged, no forward bias is applied to the element 172. Thus, the element 171 becomes on state and the element 172 becomes off state. As a result, the input current C131 flows through the branch current path 1011, and no input current flows through the branch current path 1012.

[0046] In the state shown in FIG. 2, the input power P required to drive the light source 11 is input to the PFC circuit 141. Also, the PFC circuit 141 is electrically connected to the input capacitor 131, but is electrically separated from the input capacitor 132 by the element 172. Therefore, the relationship between the input power P and the capacitance C of the input capacitor in the state shown in FIG. 2 is the same as the relationship between the input power P and the capacitance C of the input capacitor in the state shown in FIG. 1. For this reason, also in the state shown in FIG. 2, the PFC circuit 141 can effectively improve the power factor of the DC power supply device 1.

[0047] In the first embodiment, the elements 171 and 172 are inserted into the branch current paths 1011 and 1012, respectively. That is, the branch current path 1010 into which the element 170 is inserted is each of the branch current paths 1011 and 1012 included in the branch current path 1010. Therefore, the power factor of the DC power supply device 1 can be improved in any case where the drive circuit to which the light source is not connected is either the drive circuit 151 or 152.

[0048] 1.11 Comparison with a DC power supply device not provided with an element for blocking a current flowing backward FIG. 3 is a block diagram of a lighting device including the DC power supply device of the first reference example and a plurality of light sources connected to the DC power supply device. FIG. 4 is a block diagram of a lighting device including the DC power supply device of the first reference example and one light source connected to the DC power supply device.

[0049] The DC power supply device 8 of the first reference example shown in FIGS. 3 and 4 includes one PFC circuit 840 to which a plurality of drive circuits 151 and 152 are electrically connected, and includes one input capacitor 830 to which one PFC circuit 840 is electrically connected.

[0050] When light sources 11 and 12 are respectively connected to drive circuits 151 and 152 as shown in FIG. 3, drive circuits 151 and 152 respectively output drive powers P31 and P32 to light sources 11 and 12.

[0051] In the state shown in FIG. 3, an input power 2P required to drive light sources 11 and 12 is input to PFC circuit 840. For this reason, PFC circuit 840 is designed so that the power factor of DC power supply device 8 can be effectively improved according to the relationship between the input power 2P required to drive light sources 11 and 12 and the capacitance C of input capacitor 830.

[0052] As shown in FIG. 4, when light source 11 is connected to drive circuit 151 but no light source is connected to drive circuit 152, drive circuit 151 outputs drive power P31 to light source 11, but drive circuit 152 does not output drive power to the light source.

[0053] In the state shown in FIG. 4, an input power P required to drive light source 11 is input to PFC circuit 840. For this reason, the relationship between the input power P in the state shown in FIG. 4 and the capacitance C of the input capacitor is different from the relationship between the input power 2P and the capacitance C of the input capacitor in the state shown in FIG. 3. For this reason, in the state shown in FIG. 4, PFC circuit 840 cannot effectively improve the power factor of DC power supply device 8.

[0054] FIG. 5 is a block diagram of a lighting device including a DC power supply device of a second reference example and a plurality of light sources connected to the DC power supply device. FIG. 6 is a block diagram of a lighting device including a DC power supply device of a second reference example and one light source connected to the DC power supply device.

[0055] The DC power supply device 9 of the second reference example shown in FIGS. 5 and 6 includes a plurality of driving circuits 951 and 952 with built-in PFC functions. The driving circuits 951 and 952 with built-in PFC functions are electrically connected to the input capacitors 131 and 132, respectively.

[0056] As shown in FIG. 5, when the light sources 11 and 12 are connected to the driving circuits 951 and 952 with built-in PFC functions, respectively, the driving circuits 951 and 952 with built-in PFC functions output driving powers P31 and P32 to the light sources 11 and 12, respectively.

[0057] In the state shown in FIG. 5, the input power required to drive the light sources 11 and 12 is input to the driving circuits 951 and 952 with built-in PFC functions. That is, the input power P required to drive one light source 10 is input to each driving circuit 950 with built-in PFC function. Further, the driving circuits 951 and 952 with built-in PFC functions are connected to the input capacitors 131 and 132, respectively. For this reason, each driving circuit 950 with built-in PFC function shares one input capacitor 130. For this reason, each driving circuit 950 with built-in PFC function is designed so that the power factor of the DC power supply device 9 can be effectively improved according to the relationship between the input power P required to drive one light source 10 and the capacitance C of one input capacitor 130 to be shared.

[0058] As shown in FIG. 6, when the light source 11 is connected to the driving circuit 151 but no light source is connected to the driving circuit 152, the driving circuit 151 outputs the driving power P31 to the light source 11, but the driving circuit 152 does not output the driving power to the light source.

[0059] In the state shown in FIG. 6, the input power P required to drive the light source 11 is input to the drive circuit 951 with built-in PFC function. Further, the drive circuit 951 with built-in PFC function is electrically connected to the input capacitor 131 and also electrically connected to the input capacitor 132. Therefore, the relationship between the input power P and the capacitance 2C of the input capacitor in the state shown in FIG. 6 is different from the relationship between the input power P and the capacitance C of the input capacitor in the state shown in FIG. 5. For this reason, in the state shown in FIG. 6, the drive circuit 951 with built-in PFC function cannot effectively improve the power factor of the DC power supply device 9.

[0060] By comparing the DC power supply device 1 of the first embodiment with the DC power supply device 8 of the first reference example and the DC power supply device 9 of the second reference example, it can be understood that the DC power supply device 1 of the first embodiment has a high power factor even when the drive power P31 is output to a part of the drive circuits 151 included in the drive circuits 151 and 152.

[0061] 1.12 Comparison with a single-output DC power supply device Even in a lighting device including a single-output DC power supply device, a plurality of light sources electrically connected in series can be connected to a drive circuit to light the plurality of light sources. However, when one light source is connected to the drive circuit, the one light source cannot be lit. Therefore, the number of light sources to be lit cannot be changed. On the other hand, in a lighting device including the two-output DC power supply device of the first embodiment, the number of light sources 10 to be lit can be easily changed.

[0062] 2 Second Embodiment Hereinafter, the differences between the second embodiment and the first embodiment will be described. For points not described, the same configurations as those adopted in the first embodiment are also adopted in the second embodiment.

[0063] FIG. 7 is a block diagram of a lighting device including the DC power supply device of the second embodiment and a plurality of light sources connected to the DC power supply device.

[0064] In the DC power supply device 2 of the second embodiment, as shown in FIG. 7, each element 170 is an n-channel field effect transistor (FET) 280. The n-channel FET 280 includes a gate 280a, a drain 280b, and a source 280c. The n-channel FET 280 is a metal oxide semiconductor field effect transistor (MOSFET). Therefore, the n-channel FET 280 incorporates a parasitic diode. The anode of the parasitic diode is electrically connected to the source 280c. The cathode of the parasitic diode is electrically connected to the drain 280b. The first terminal 170a of each element 170 is the source 280c. The second terminal 170b of each element 170 is the drain 280b.

[0065] When an on potential is applied to the gate 280a, a channel is formed in the n-channel FET 280 from the source 280c to the drain 280b. As a result, when an on potential is applied to the gate 280a, the n-channel FET 280 conducts the drain 280b to the source 280c through the formed channel. Thus, when an on potential is applied to the gate 280a, the n-channel FET 280 permits current to flow from the source 280c through the channel to the drain 280b.

[0066] When an off potential is applied to the gate 280a, the channel is not formed in the n-channel FET 280. As a result, when an off potential is applied to the gate 280a, the n-channel FET 280 conducts the drain 280b to the source 280c through the parasitic diode. Thus, when an off potential is applied to the gate 280a, the n-channel FET 280 permits current to flow from the source 280c through the parasitic diode to the drain 280b and blocks current from flowing from the drain 280b to the source 280c.

[0067] As shown in FIG. 7, the DC power supply device 2 of the second embodiment includes a control circuit 290.

[0068] The control circuit 290 applies an on potential to the gate 280a of the n-channel FET 280 corresponding to the drive circuit 150 to which the light source 10 is connected. Thereby, it is possible to suppress the loss of the input current C130 flowing through the branch current path 1010 corresponding to the drive circuit 150 to which the light source 10 is connected.

[0069] The control circuit 290 applies an off potential to the gate 280a of the n-channel FET 280 corresponding to the drive circuit 150 to which no light source is connected. Thereby, it is possible to prevent a current C150 flowing in a direction opposite to the direction of the input current C130 from flowing through the branch current path 1010 corresponding to the drive circuit 150 to which no light source is connected.

[0070] 3 Third Embodiment Hereinafter, differences between the third embodiment and the first embodiment will be described. For points not described, the same configurations as those employed in the first embodiment are also employed in the third embodiment.

[0071] FIG. 8 is a block diagram of an illumination device including the DC power supply device of the third embodiment and a plurality of light sources connected to the DC power supply device.

[0072] In the DC power supply device 3 of the third embodiment, as shown in FIG. 8, each element 170 is a p-channel FET 380. The p-channel FET 380 includes a gate 380a, a drain 380b, and a source 380c. The p-channel FET 380 is a MOSFET. Therefore, the p-channel FET 380 incorporates a parasitic diode. The anode of the parasitic diode is electrically connected to the drain 380b. The cathode of the parasitic diode is electrically connected to the source 380c. The first terminal 170a of each element 170 is the drain 380b. The second terminal 170b of each element 170 is the source 380c.

[0073] When an on - potential is applied to gate 380a, a channel is formed in p - channel FET 380 from drain 380b to source 380c. As a result, when an on - potential is applied to gate 380a, p - channel FET 380 conducts source 380c to drain 380b through the formed channel. Thus, when an on - potential is applied to gate 380a, p - channel FET 380 permits current to flow from drain 380b through the channel to source 380c.

[0074] When an off - potential is applied to gate 380a, the channel is not formed in p - channel FET 380. As a result, when an off - potential is applied to gate 380a, p - channel FET 380 conducts source 380c to drain 380b through the parasitic diode. Thus, when an off - potential is applied to gate 380a, p - channel FET 380 permits current to flow from drain 380b through the parasitic diode to source 380c and blocks current from flowing from source 380c to drain 380b.

[0075] As shown in FIG. 8, the DC power supply device 3 of the third embodiment includes a control circuit 390.

[0076] The control circuit 390 applies an on - potential to the gate 380a of the p - channel FET 380 corresponding to the drive circuit 150 to which the light source 10 is connected. Thereby, the loss of the input current C130 flowing through the branch current path 1010 corresponding to the drive circuit 150 to which the light source 10 is connected can be suppressed.

[0077] The control circuit 390 applies an off - potential to the gate 380a of the p - channel FET 380 corresponding to the drive circuit 150 to which the light source 10 is not connected. Thereby, it is possible to prevent a current C150 flowing in a direction opposite to the direction of the input current C130 from flowing through the branch current path 1010 corresponding to the drive circuit 150 to which the light source 10 is not connected.

[0078] 4 Fourth Embodiment Hereinafter, the differences between the fourth embodiment and the first embodiment will be described. Regarding the points not described, the same configuration as that adopted in the first embodiment is also adopted in the fourth embodiment.

[0079] FIG. 9 is a block diagram of an illumination device including a DC power supply device according to the fourth embodiment and a plurality of light sources connected to the DC power supply device.

[0080] In the DC power supply device 4 of the fourth embodiment, as shown in FIG. 9, each element 170 is a mechanical switch 480. The mechanical switch 480 includes a first terminal 480a and a second terminal 480b. The mechanical switch 480 switches the state between the first terminal 480a and the second terminal 480b between a state where the second terminal 480b is conductive to the first terminal 480a and a state where the second terminal 480b is not conductive to the first terminal 480a according to an operation performed on the operator of the mechanical switch 480.

[0081] The user sets the state between the first terminal 480a and the second terminal 480b of the mechanical switch 480 corresponding to the drive circuit 150 to which the light source 10 is connected to a state where the second terminal 480b is conductive to the first terminal 480a. Thereby, the loss of the input current C130 flowing through the branch current path 1010 corresponding to the drive circuit 150 to which the light source 10 is connected can be suppressed.

[0082] The user sets the state between the first terminal 480a and the second terminal 480b of the mechanical switch 480 corresponding to the drive circuit 150 to which the light source 10 is not connected to a state where the second terminal 480b is not conductive to the first terminal 480a. Thereby, it is possible to prevent a current C150 flowing in a direction opposite to the direction of the input current C130 from flowing through the branch current path 1010 corresponding to the drive circuit 150 to which the light source 10 is not connected.

[0083] 5 Fifth Embodiment Hereinafter, the differences between the fifth embodiment and the first embodiment will be described. For points not described, the same configurations as those employed in the first embodiment are also employed in the fifth embodiment.

[0084] FIG. 10 is a block diagram of a lighting device including the DC power supply device of the fifth embodiment and a plurality of light sources connected to the DC power supply device.

[0085] In the DC power supply device 5 of the fifth embodiment, as shown in FIG. 10, no element is inserted into the branch current path 1011, and only the element 172 is inserted into the branch current path 1012. That is, the branch current path 1012 into which the element 170 is inserted is each a part of the branch current paths 1011 and 1012. The DC power supply device 5 is preferably employed when the drive circuit 150 to which the light source 10 is not connected is limited.

[0086] In the DC power supply device 5 of the fifth embodiment, it is possible to suppress the loss caused by the voltage drop in the diode 180 of the input current C131 flowing through the branch current path 1011 into which no element is inserted. Thereby, the efficiency of the power supply of the DC power supply device 5 can be increased.

[0087] 6 Sixth Embodiment FIG. 11 is a block diagram of a lighting system including the lighting fixture of the sixth embodiment and other lighting fixtures connected to the lighting fixture.

[0088] As illustrated in FIG. 11, the lighting system 6001 includes a lighting fixture 6011 and other lighting fixtures 6012. The lighting fixture 6011 includes a DC power supply device 6021, a light source 6022, and a connection part 6023. The other lighting fixture 6012 includes a connection part 6031 and other light sources 6032.

[0089] The DC power supply device 6021 is the DC power supply device 1 of the first embodiment, the DC power supply device 2 of the second embodiment, the DC power supply device 3 of the third embodiment, the DC power supply device 4 of the fourth embodiment, or the DC power supply device 5 of the fifth embodiment.

[0090] The light source 6022 is electrically connected to the drive circuit 151. Therefore, the light source 6022 is driven by the drive power P31, which is the first drive power included in the drive powers P31 and P32.

[0091] The connection part 6023 is electrically connected to the drive circuit 152. Therefore, the drive power P32, which is the second drive power included in the drive powers P31 and P32 and different from the first drive power, is input to the connection part 6023. Another lighting fixture 6012 can be connected to the connection part 6023. When another lighting fixture 6012 is connected, the connection part 6023 outputs the drive power P32 to the other lighting fixture 6012.

[0092] The connection part 6031 can be connected to the connection part 6023. When the connection part 6031 is connected to the connection part 6023, the drive power P32 is input to the connection part 6031. The connection part 6031 outputs the input drive power P32 to another light source 6032.

[0093] Another light source 6032 is electrically connected to the connection part 6031. As a result, the output drive power P32 is input to another light source 6032. Another light source 6032 is driven by the input drive power P32.

[0094] The connection part 6023 is, for example, one connector. The connection part 6031 is, for example, the other connector that can engage with and disengage from one connector.

[0095] FIG. 12 is a block diagram of a lighting system including the lighting fixture of the sixth embodiment.

[0096] As shown in FIG. 12, the lighting fixture 6011 can be used even when not connected to other lighting fixtures 6012. A drive circuit 152 that outputs a drive power P32 for driving another light source 6032 is electrically connected to an input capacitor 132 via a PFC circuit 142. An element 172 is inserted into a branch current path 1012 through which an input current C132 input to the input capacitor 132 flows. Thereby, even when other lighting fixtures 6012 are not connected to the lighting fixture 6011, the DC power supply device 6021 has a high power factor.

[0097] 7 Seventh Embodiment FIG. 13 is a block diagram of a lighting system including a lighting fixture according to the seventh embodiment and a first light source connected to the lighting fixture. FIG. 14 is a block diagram of a lighting system including a lighting fixture according to the seventh embodiment and a second light source connected to the lighting fixture.

[0098] As shown in FIGS. 13 and 14, the lighting fixture 7001 includes a DC power supply device 7011 and a connection part 7012.

[0099] The DC power supply device 7011 is the DC power supply device 1 of the first embodiment, the DC power supply device 2 of the second embodiment, the DC power supply device 3 of the third embodiment, the DC power supply device 4 of the fourth embodiment, or the DC power supply device 5 of the fifth embodiment. The first light source 7021 includes a first connection part 7051. The second light source 7022 includes a second connection part 7052.

[0100] The connection part 7012 is electrically connected to the drive circuits 151 and 152. For this reason, drive powers P31 and P32 are input to the connection part 7012. A light source can be connected to the connection part 7012. When a light source is connected to the connection part 7012, the connection part 7012 outputs at least one of the drive powers included in the drive powers P31 and P32 to the connected light source. The at least one drive power output varies according to the connected light source. For example, as shown in FIG. 13, when the first light source 7021 is connected, the connection part 7012 outputs the drive powers P31 and P32 to the first light source 7021. In this case, the first light source 7021 lights up with the brightness equivalent to that of two lamps. Also, as shown in FIG. 14, when the second light source 7022 is connected, the connection part 7012 outputs the drive power P31 to the second light source 7022. In this case, the second light source 7022 lights up with the brightness equivalent to that of one lamp.

[0101] The connection part 7012 is, for example, one connector. Each of the first connection part 7051 and the second connection part 7052 is, for example, the other connector that can engage with one connector and can be disengaged from one connector.

[0102] The connection part 7012 includes output parts 7031 and 7032 that output the drive powers P31 and P32 respectively.

[0103] The first connection part 7051 includes power supply lines 7061 and 7062 that are electrically connected to the output parts 7031 and 7032 respectively when the first connection part 7051 is connected to the connection part 7012. Thereby, when the first light source 7021 is connected to the connection part 7012, the first light source 7021 is driven by the drive powers P31 and P32.

[0104] The second connection part 7052 includes a power supply line 7061 that is electrically connected to the output part 7031 when the second connection part 7052 is connected to the connection part 7012, but does not include a power supply line that is electrically connected to the output part 7032 when the second connection part 7052 is connected to the connection part 7012. Thereby, when the second light source 7022 is connected to the connection part 7012, it is driven by the driving power P31. Even in this case, the power factor of the DC power supply device 7011 is good.

[0105] The present disclosure is not limited to the above-described embodiments, and may be replaced with a configuration that is substantially the same as the configuration shown in the above-described embodiments, a configuration that exhibits the same operational effects, or a configuration that can achieve the same object.

Explanation of Reference Numerals

[0106] 1, 2, 3, 4, 5, 8, 9 DC power supply device, 10, 11, 12 light sources, 100 circuit ground, 110 input section, 110a, 110b terminals, 120 rectifier, 120a, 120b input terminals, 120c, 120d output terminals, 130, 131, 132 input capacitors, 130a, 130b terminals, 140 power factor correction (PFC) circuit, 141, 142 PFC circuits, 150, 151, 152 drive circuits, 161, 162 output sections, 170, 171, 172 elements, 170a first terminal, 170b second terminal, 180 diode, 180a anode, 180b cathode, 1000 current path, 1010, 1011, 1012 branched current paths, 280 n-channel field effect transistor (FET), 280a gate, 280b drain, 280c source, 290 control circuit, 380 p-channel FET, 380a gate, 380b drain, 380c source, 390 control circuit, 480 mechanical switch, 480a first terminal, 480b second terminal, 6001 lighting system, 6011 lighting fixture, 6012 other lighting fixture, 6021 DC power supply device, 6022 light source, 6023 connection section, 6031 connection section, 6032 other light source, 7001 lighting fixture, 7011 DC power supply device, 7012 connection section, 7021 first light source, 7022 second light source, 7031, 7032 output sections, 7051 first connection section, 7052 second connection section, 7061, 7062 power supply lines, 830 input capacitor, 840 PFC circuit, 950, 951, 952 drive circuits with built-in PFC function, P10 AC power, P21, P22 output power, P31, P32 drive power, L11, L12 light, C110 output current, C120 output current, C130, C131, C132 input current, C141, C142 input current, C150, C151, C152 current.

Claims

1. A rectifier having an output terminal for rectifying an alternating current and outputting an output current; A circuit ground; A plurality of input capacitors electrically connected in parallel between the output terminal and the circuit ground, and into which a plurality of input currents obtained by shunting the output current are respectively input; A plurality of branch current paths through which the plurality of input currents respectively flow; A plurality of power factor improvement circuits electrically connected to the plurality of input capacitors respectively; A plurality of drive circuits electrically connected to the plurality of power factor improvement circuits respectively, and outputting a plurality of drive powers respectively; An element that prevents current from flowing in a direction opposite to the direction of the input current flowing through a branch current path included in the plurality of branch current paths; A DC power supply device comprising the above.

2. The element is a diode having an anode electrically connected to the output terminal and a cathode electrically connected to the input capacitor into which the input current is input. The DC power supply device according to Claim 1.

3. The element is an n-channel field effect transistor having a source electrically connected to the output terminal, a drain electrically connected to the input capacitor into which the input current is input, and a gate. The DC power supply device according to Claim 1.

4. The element is a p-channel field effect transistor having a drain electrically connected to the output terminal, a source electrically connected to the input capacitor into which the input current is input, and a gate. The DC power supply device according to Claim 1.

5. The element includes a first terminal electrically connected to the output terminal and a second terminal electrically connected to the input capacitor into which the input current is input, and is a mechanical switch that switches the conduction state between the first terminal and the second terminal between a state in which the second terminal conducts with the first terminal and a state in which the second terminal does not conduct with the first terminal. The DC power supply device according to Claim 1.

6. The branch current path is each of the plurality of branch current paths. The DC power supply device according to any one of Claims 1 to 5.

7. The branch current path is each of some of the plurality of branch current paths. The DC power supply device according to any one of Claims 1 to 5.

8. The DC power supply device according to any one of Claims 1 to 5; A light source driven by a first drive power included in the plurality of drive powers. It is possible to connect other lighting fixtures, and a connection part that outputs a second driving power different from the first driving power included in the plurality of driving powers to the other lighting fixtures when the other lighting fixtures are connected; A lighting fixture comprising the same.

9. The branch current path is a branch current path through which an input current flowing into an input capacitor to which a driving circuit that outputs the second driving power is electrically connected via a power factor improvement circuit flows. The lighting fixture according to Claim 8.

10. The lighting fixture according to Claim 8, And the other lighting fixtures, Comprising: The other lighting fixtures are connected to the connection part, The other lighting fixtures include other light sources driven by the second driving power. A lighting system.

11. The DC power supply device according to any one of Claims 1 to 5, A connection part that can connect a light source and outputs at least one driving power included in the plurality of driving powers to the light source when the light source is connected, and changes the at least one driving power according to the light source; A lighting fixture comprising the same.

12. The lighting fixture according to Claim 11, And the light source, A lighting system comprising the same.

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