JP2011119237A - Led lighting device and lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED lighting device capable of operating more efficiently, and to provide a luminaire equipped with the same. <P>SOLUTION: The LED lighting device comprises at least one normally-on type switching element, an output generation unit that generates DC output by an on-off operation of the switching element, a semiconductor light emitting element that is lit by the DC output generated by the output generation unit, and a driving control unit that causes the switching element to perform an off operation using a current passed through the semiconductor light emitting element. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  Embodiments described herein relate generally to an LED lighting device and a lighting fixture including the LED lighting device.

In recent years, with the improvement of optical performance of light emitting diode (LED) elements, devices using LED elements as light sources have been put into practical use. As an LED lighting device for lighting an LED element, for example, a DC LED lighting device using switching means is widely used.

  Conventionally, a transistor using a Si (silicon) semiconductor or the like is used as a switching means (switching element) of the LED lighting device. In addition, a transistor using a wide band gap semiconductor such as SiC (silicon carbide), GaN (gallium nitride), or diamond attracts attention.

  Wide gap semiconductors generally have normally-on characteristics in which current flows when the gate voltage is zero. Semiconductor elements using a wide gap semiconductor include, for example, JFET (junction FET), SIT (electrostatic induction transistor), MESFET (metal-semiconductor-field-effect-transistor), HFET (Heterojunction Field). Effect Transistor), HEMT (High Electron Mobility Transistor), and storage FET.

  In order to reliably turn off a semiconductor element having normally-on characteristics (hereinafter referred to as a normally-on switch), the LED lighting device needs to include a control circuit for a negative gate voltage.

  It is also known that an LED lighting device with high circuit efficiency can be obtained by lighting an LED element using a DC-DC converter. The DC-DC converter can perform constant current control by driving the switch element using the electromotive force generated by induction.

JP 2009-218528 A JP 2007-006658 A Japanese Patent No. 4123886

  An object of the present invention is to provide an LED lighting device that can operate more efficiently and a lighting fixture including the LED lighting device.

  An LED lighting device according to an embodiment includes at least one normally-on type switching element, an output generation unit that generates a DC output by an on / off operation of the switching element, and a DC generated by the output generation unit A semiconductor light-emitting element that is turned on by an output; and drive control means for turning off the switching element using a current flowing through the semiconductor light-emitting element.

Drawing 1 is a figure showing an example of a lighting fixture concerning one embodiment. FIG. 2 is a diagram illustrating a configuration example of an LED lighting device according to an embodiment. FIG. 3 is a diagram illustrating a configuration example of an LED lighting device according to an embodiment. FIG. 4 is a diagram illustrating a configuration example of a constant voltage power supply according to an embodiment. FIG. 5 is a diagram illustrating a configuration example of an LED lighting device according to an embodiment. FIG. 6 is a diagram illustrating a configuration example of an LED lighting device according to an embodiment. FIG. 7 is a diagram illustrating a configuration example of an LED lighting device according to an embodiment. FIG. 8 is a diagram illustrating a configuration example of an LED lighting device according to an embodiment. FIG. 9 is a diagram illustrating an example of current and voltage waveforms in each unit of the LED lighting device according to the embodiment. FIG. 10 is a diagram illustrating a configuration example of an LED lighting device according to an embodiment. FIG. 11 is a diagram illustrating a configuration example of an LED lighting device according to an embodiment. FIG. 12 is a diagram illustrating a configuration example of an LED lighting device according to an embodiment. FIG. 13 is a diagram illustrating an example of current and voltage waveforms in each part of the LED lighting device according to the embodiment. FIG. 14 is a diagram illustrating a configuration example of an LED lighting device according to an embodiment. FIG. 15 is a diagram illustrating a configuration example of an LED lighting device according to an embodiment. FIG. 16 is a diagram illustrating an example of an integrated circuit module of the LED lighting device according to the embodiment. FIG. 17 is a diagram illustrating an example of an integrated circuit module of the LED lighting device according to the embodiment.

  Hereinafter, embodiments will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a perspective view showing a lighting fixture to which the power supply device (LED lighting device) according to the first embodiment is applied. First, the lighting fixture provided with a power supply device is demonstrated easily.

  In FIG. 1, 1 is an instrument main body. The instrument body 1 has a disk-shaped base 1a. Then, ring-shaped LED lighting lamps 2 and 3 having different diameters are concentrically arranged as light sources on the base 1a. A milky white shade 4 is mounted so as to cover the LED lighting lamps 2 and 3. A power supply device 100 is disposed inside the instrument body 1. In addition, although not shown in the drawing, a reflector, a terminal, wiring, and the like may be further provided in the instrument body 1.

  FIG. 2 shows a schematic configuration of the power supply apparatus 100 incorporated in the fixture main body 1 of the lighting fixture shown in FIG.

  In FIG. 2, 10 is an AC power source. The AC power supply 10 includes a commercial power supply (not shown). An input terminal of a full wave rectifier circuit 11 is connected to the AC power supply 10. The full-wave rectifier circuit 11 generates an output obtained by full-wave rectifying AC power from the AC power supply 10. A ripple current smoothing capacitor 12 is connected between the positive and negative output terminals of the full-wave rectifier circuit 11.

  A normally-on type field effect transistor 13 made of GaN, for example, is connected to the capacitor 12 as a switching element constituting the step-down chopper.

  The field effect transistor 13 is formed by bonding different kinds of semiconductor materials having different band gaps. The field effect transistor 13 includes a two-dimensional electron gas layer at the interface. The field effect transistor 13 can realize high-speed switching and sensitivity by the effect of the two-dimensional electron gas layer. The field effect transistor 13 is called HEMT (High Electron Mobility Transistor).

  The field effect transistor 13 has a gate-source voltage of Vgs and a gate voltage threshold of Vth (negative voltage). The field effect transistor 13 is turned off when Vth> Vgs, and turned on when Vth <Vgs.

  The drain of the field effect transistor 13 is connected to the positive output terminal of the full-wave rectifier circuit 11. The source of the field effect transistor 13 is an output terminal on the positive side of the full-wave rectifier circuit 11 via a series circuit of an LED element group 14 having a plurality of LED elements connected in series as semiconductor light emitting elements, a resistor element 15 and an inductor 16. Connected to. The gate of the field effect transistor 13 is connected to a connection point between the resistance element 15 and the inductor 16 via a normally-off type field effect transistor 18 as a switching element that forms drive control means.

  In the field effect transistor 13, a diode 19 of the illustrated polarity for gate protection is connected between the source and the gate.

  The LED element group 14 corresponds to the LED illumination lamps 2 and 3 shown in FIG. When a current flows through the LED element group 14, a forward voltage having the polarity shown is generated at both ends. The field effect transistor 13 is turned off by applying a forward voltage negative potential between the source and gate of the field effect transistor 13. A capacitor 20 is connected to the LED element group 14 in parallel.

  The inductor 16 has a coupled auxiliary winding 161. One end of the auxiliary winding 161 is connected to a connection point between the resistance element 15 and the inductor 16. The other end of the auxiliary winding 161 is connected to the gate of the field effect transistor 18 through the diode 21 having the polarity shown in the figure. Then, by accumulating and releasing electromagnetic energy in the inductor 16 accompanying the on / off operation of the field effect transistor 13, a stepped-down DC output is generated across the capacitor 20 via the flywheel diode 22. Further, a self-excited circuit for turning on and off the field effect transistor 18 is configured by the output of the auxiliary winding 161 synchronized with the accumulation and release of electromagnetic energy in the inductor 16.

  The resistance element 15 is connected to a comparator 23 that constitutes constant current control means. The comparator 23 is connected to the gate of the field effect transistor 18 through the diode 24 having the polarity shown in the figure. The comparator 23 is connected to a power source 17 that generates a preset reference signal Vf at one input terminal. A load current flowing through the resistance element 15 is input to the other terminal of the comparator 23. The comparator 23 compares the input load current with the reference signal Vf. The comparator 23 forcibly turns on the field effect transistor 18 when the load current reaches the reference signal Vf in the comparison result.

  Next, the operation of the embodiment configured as described above will be described.

  Now, when the power is turned on by a power switch (not shown), a forward voltage having the polarity shown is generated at both ends of the LED element group 14 via the field effect transistor 13 in the on state. Further, when the current flowing through the LED element group 14 becomes the reference signal Vf of the comparator 23 by turning on the field effect transistor 13, the field effect transistor 18 is turned on, and the negative potential due to the forward voltage of the LED element group 14 is changed to the field effect transistor. Applied between 13 sources and gates. In this case, Vth> Vgs and the field effect transistor 13 is turned off. In this state, a signal for continuing to turn on the field effect transistor 18 is generated from the auxiliary winding 161 of the inductor 16. When the inductor 16 finishes discharging, the field effect transistor 18 is turned off. In this case, since Vth <Vgs, the field effect transistor 13 is turned on again.

  Thereafter, the same operation is repeated, and the field effect transistor 13 is turned on / off by the switching operation of the field effect transistor 18. Due to the accumulation and release of electromagnetic energy in the inductor 16, a stepped-down DC output is generated across the capacitor 20 via the flywheel diode 22. The LED element group 14 is turned on by this DC output.

  Further, when the load current flowing through the resistance element 15 becomes a preset reference signal Vf of the comparator 23, the field effect transistor 18 is turned on and the field effect transistor 13 is turned off. As a result, the load current is limited, and the load current flowing through the LED element group 14 is always controlled to coincide with the reference signal Vf, and constant current control is performed.

  Therefore, in this case, the normally-on type field effect transistor 13 is used as a switching element constituting the step-down chopper, and the field effect transistor 13 is turned off using the forward voltage generated in the LED element group 14. become able to. As a result, a special power supply circuit is not incorporated to obtain a negative voltage for turning off the normally-on type field effect transistor 13, and the number of components can be reduced. In addition, the circuit configuration can be simplified, the apparatus can be miniaturized, and the price can be reduced.

  In addition, an appropriate negative potential of Vth> Vgs (gate-source voltage) can be obtained with respect to the threshold voltage Vth of the gate voltage of the field effect transistor 13 by the forward voltage generated in the semiconductor light-emitting element 14. The field effect transistor can be reliably turned off.

  Further, a normally-on type field effect transistor 13 made of GaN is used as the switching element. The field effect transistor 13 can increase the frequency without degrading the efficiency. As a result, the capacitance of impedance elements such as inductors and capacitors constituting the circuit can be reduced, and modularization can be realized by further downsizing the apparatus.

  Furthermore, the LED element group 14 can be dimmed by changing the reference voltage Vf of the power source 17 by an external operation or the like. In this case, for example, it is preferable to provide a receiving circuit that receives a control signal via an insulating type input means such as a remote controller or a photocoupler on the side of a substrate (not shown) on which the LED element group 14 is mounted.

  In order to optimally set the forward voltage generated at both ends of the LED element group 14, the number of LED elements in series is limited. Therefore, when an LED illumination lamp requires a larger number of LED elements. An appropriate number or more of LED elements may be connected in series with the inductor 16.

(Second Embodiment)
Next, a second embodiment will be described.

  FIG. 3 shows a schematic configuration of the second embodiment, and the same parts as those in FIG.

  In this case, between the capacitors 12 connected between the positive and negative output terminals of the full-wave rectifier circuit 11, a plurality of LED elements connected in series as semiconductor light emitting elements are connected in series with, for example, GaN. A series circuit of normally-on type field effect transistors 32 and 33 is connected as a switching element. These field effect transistors 32 and 33 also have a gate voltage threshold Vth of a negative voltage, and are turned off when Vth> Vgs (gate-source voltage) and turned on when Vth <Vgs. The field effect transistors 32 and 33 have diodes 32a and 33a having polarities shown in the figure connected between the source and drain, respectively.

  A capacitor 34 is connected in parallel to the series circuit of the field effect transistors 32 and 33, and a series circuit of an inductor 35 and a capacitor 36 is connected in parallel to the field effect transistor 33. In the field effect transistor 32, a diode 37 having the illustrated polarity is connected between a gate and a source, and a first drive source 39 is connected between the diode 37 via a capacitor 38. In the field effect transistor 33, a diode 40 having the illustrated polarity is connected between a gate and a source, and a second drive source 42 is connected between the diode 40 via a capacitor 41. The first and second drive sources 39 and 42 output positive and negative pulse signals via the capacitors 38 and 41, and convert the negative voltage signal half-wave rectified by the diodes 37 and 40 into the field effect transistors 32, Input alternately between 33 gate sources.

  A normally-on type field effect transistor 43 made of, for example, GaN is connected to a connection point between the capacitor 12 and the LED element group 31 as a switching element serving as drive control means. The field effect transistor 43 has a drain connected to the connection point between the capacitor 12 and the LED element group 31, and a source connected to the gate of the field effect transistor 33 via the capacitor 44. Further, the field effect transistor 43 has a gate connected to a connection point between the capacitor 44 and the gate of the field effect transistor 33. When the power is turned on, a negative potential is generated in the capacitor 44 by the forward voltage of the LED element group 31. Input to 33 gates. In the field effect transistor 43, a diode 43a having the illustrated polarity is connected between the source and drain.

  Next, the operation of the embodiment configured as described above will be described.

  Now, when power is turned on by a power switch (not shown) and a forward voltage is generated in the LED element group 31, a charging current flows to the capacitor 44 via the field effect transistor 43 in the on state by this forward voltage, Charged to the polarity shown. Then, the negative potential of the capacitor 44 is applied to the gate of the field effect transistor 33, and the field effect transistor 33 is turned off. As a result, a short circuit between the LED element group 31 and the on-state field effect transistors 32 and 33 at the time of starting the power supply is prevented, and an accident where the overcurrent flows and the LED element group 31 is damaged is prevented. The charged charge of the capacitor 44 is discharged through the diode 43a of the field effect transistor 43.

  Thereafter, a negative voltage signal is alternately input between the gate sources of the field effect transistors 32 and 33 via the diodes 37 and 40 by the outputs from the first and second drive sources 39 and 42. First, when the field effect transistor 32 is turned on, and a negative voltage signal is input to the gate of the field effect transistor 33 from the second drive source 42 and turned off, the LED element group 31, the field effect from the positive side of the full-wave rectifier circuit 11. Current flows to the negative side of the transistor 32, the inductor 35, the capacitor 36, and the full-wave rectifier circuit 11, and electromagnetic energy is stored in the inductor 35. In this state, when a negative voltage signal is input to the gate of the field effect transistor 32 from the first drive source 39 and turned off, the electromagnetic energy of the inductor 35 passes through the capacitor 36 and the diode 33 a of the field effect transistor 33, and the capacitor 36. Continue charging current. Up to this point, the operation of the step-down chopper using the capacitor 36 as an output capacitor is performed.

  Next, when the field effect transistor 33 is turned on and a negative voltage signal is input to the gate of the field effect transistor 32 from the first drive source 39 and turned off, the charging current disappears, and the inductor 35 and the field effect transistor 33 are removed from the capacitor 36. A discharge current flows through the inductor 35 and electromagnetic energy is stored in the inductor 35. In this state, when a negative voltage signal is input to the gate of the field effect transistor 33 from the second drive source 42 and turned off, electromagnetic energy of the inductor 35 flows through the diode 32 a and the capacitor 34 of the field effect transistor 32. . Thereafter, when the same operation is repeated, a load current continues to flow through the LED element group 31, and the LED element group 31 is lit by this current.

  Therefore, in this way, when the power supply is turned on, the forward voltage of the LED element group 31 is used to charge the capacitor 44 through the normally-on type field effect transistor 43 to charge the capacitor 44. The normally-on type field effect transistor 33 constituting the switching circuit can be turned off by the negative potential 44. In this case, the same effect as that of the first embodiment can be obtained. Furthermore, since a circuit short-circuit at the time of starting the power supply by turning on the field effect transistors 32 and 33 can be prevented, an overcurrent does not flow through the LED element group 31 reliably, and an accident such as breakage of the LED element group 31 occurs. Can be prevented.

(Modification)
FIG. 4 is a diagram showing a schematic configuration of a constant voltage power source applied to the second embodiment. In the second embodiment, a constant voltage power source as shown in FIG. 4 can be applied as the power source. In this case, the drain of the normally-on type field effect transistor 47 is connected to the positive electrode side end of the DC power source 46, and the source of the field effect transistor 47 is connected to the negative electrode side end of the DC power source 46 via the capacitor 48. Yes. Further, a zener diode 49 having the polarity shown in the figure is connected between the gate of the field effect transistor 47 and the negative end of the DC power supply 46. The Zener diode 49 generates a constant voltage due to the Zener effect.

  In this way, when the field effect transistor 47 is turned on, a constant voltage Vc generated by the Zener diode 49 is generated between the capacitors 48, and this constant voltage can be used as a power source.

(Third embodiment)
Next, a third embodiment will be described.

  FIG. 5 shows a schematic configuration of the third embodiment, and the same parts as those in FIG.

  In this case, between the capacitors 12 connected to the positive and negative output terminals of the full-wave rectifier circuit 11, as a switching element, for example, a series circuit of normally-on type field effect transistors 51 and 52 made of GaN, as well as GaN. Are connected to a series circuit of normally-on type field effect transistors 53 and 54 connected in parallel and a series circuit of LED element group 55 having a plurality of LED elements connected in series as semiconductor light emitting elements. Yes. An inductor 65 is connected between the connection point of the field effect transistors 51 and 52 and the connection point of the field effect transistors 53 and 54.

  The field effect transistors 51 to 54 are also normally-on type transistors in which the gate voltage threshold Vth is a negative voltage, is off when Vth> Vgs (gate-source voltage), and is on when Vth <Vgs. In the field effect transistors 51 to 54, diodes 51a to 54a having polarities shown in the figure are connected between the source and the drain, respectively. In the field effect transistors 51 to 54, gate protection diodes 56 to 59 are individually connected between the gate sources. Further, a capacitor 60 is connected in parallel to the bridge circuit of the field effect transistors 51 to 54.

  When a current flows, the LED element group 55 generates a forward voltage having the polarity shown in the figure at both ends, and the ground G side is set to a negative potential by the forward voltage. In this case, the negative potential on the ground G side is set to be equal to or lower than the threshold voltage Vth of the gate voltage of the field effect transistors 51 to 54.

  The field effect transistors 51 and 54 have respective gates connected in common, and as a drive control means, the field effect transistors 52 and 53 are respectively connected to the ground G via the normally on type field effect transistor 61 made of GaN. Are connected in common, and are connected to the ground G through normally-on type field effect transistors 62 of GaN as drive control means.

  In the field effect transistors 61 and 62, diodes 61a and 62a having polarities shown in the figure are connected between the source and the drain, respectively. These field effect transistors 61 and 62 constitute a switch drive unit 64 together with the drive source 63. The drive source 63 is connected to the gates of the field effect transistors 61 and 62, and alternately inputs a negative voltage signal to the gates of the field effect transistors 61 and 62.

  Reference numerals 65 and 66 denote resistance elements for accelerating the return of the field effect transistors 52 to 54 from the off state to the on state.

  Next, the operation of the embodiment configured as described above will be described.

  Now, when the power is turned on by a power switch (not shown), the field effect transistors 51 to 54 are turned on to generate a forward voltage having the polarity shown in the LED element group 55, and the ground G side is set to a negative potential. In this state, a negative potential on the ground G side is applied to each gate of the field effect transistors 51 to 54 through the field effect transistors 61 and 62 in the on state, and the field effect transistors 51 to 54 are turned off. Thereby, the circuit short circuit by the field effect transistors 51-54 and the LED element group 55 at the time of power supply starting is prevented.

  Thereafter, a negative voltage signal is alternately input to the gates of the field effect transistors 61 and 62 by the output from the drive source 63 of the switch drive unit 64. First, when the field effect transistors 51 and 54 are turned on, the field effect transistor 62 is turned on to the gates of the field effect transistors 52 and 53, and a negative potential on the ground G side is applied and turned off, the electric field is applied from the positive side of the full-wave rectifier circuit 11. Current flows through the effect transistor 51, the inductor 65, the field effect transistor 54, and the LED element group 55, and electromagnetic energy is stored in the inductor 65. In this state, when the field effect transistor 61 is turned on and a negative potential on the ground G side is applied to the gates of the field effect transistors 51 and 54 and turned off, the electromagnetic energy of the inductor 65 is changed to the diode 53a, A charging current is passed through the capacitor 60 and the diode 52a of the field effect transistor 52.

  Next, when the field effect transistors 52 and 53 are turned on, the field effect transistor 61 is turned on to the gates of the field effect transistors 51 and 54, and the negative potential of the ground G is applied and turned off, the field effect transistor 53 and the inductor 65 are turned off from the capacitor 60. A discharge current flows through the field effect transistor 52 and electromagnetic energy is stored in the inductor 65. In this state, when the field effect transistor 62 is turned on and the negative potential of the ground G is applied to the gates of the field effect transistors 52 and 53 and turned off, the electromagnetic energy of the inductor 65 is changed to the diode 51a of the field effect transistor 51, the capacitor 60, it flows as a charging current through the diode 54a of the field effect transistor 54. Thereafter, when the same operation is repeated, a load current continues to flow through the LED element group 55, and the LED element group 55 is lit by this current.

  Therefore, in this way, when the power is turned on, the ground G side is set to a negative potential by the forward voltage of the LED element group 31, and the normally-on type of the switching circuit is configured by the negative potential on the ground G side. The field effect transistors 51 to 54 can be turned off. In this case, the same effect as that of the first embodiment can be obtained. Further, since the circuit short circuit at the time of starting the power supply due to the ON of the field effect transistors 51 to 54 can be prevented, it is possible to surely prevent the overcurrent from flowing through the LED element group 55 and to cause an accident such as breakage of the LED element group 31. Can also be prevented.

(Fourth embodiment)
Next, a fourth embodiment will be described.

  FIG. 6 shows a schematic configuration of the fourth embodiment, and the same parts as those in FIG.

  In this case, a normally-on type field effect transistor 71 made of GaN, for example, is connected to the capacitor 12 as a switching element constituting the step-down chopper, as described in the first embodiment.

  In this field effect transistor 71, the gate voltage threshold Vth is a negative voltage. The field effect transistor 71 is turned off when Vth> Vgs (gate-source voltage) and turned on when Vth <Vgs. The field effect transistor 71 has a drain connected to the output terminal on the positive side of the full-wave rectifier circuit 11, and an LED element group 72 including a plurality of LED elements connected in series with the source as a semiconductor light emitting element, a resistance element 73, and an inductor 74. Are connected to the positive-side output terminal of the full-wave rectifier circuit 11.

  The LED element group 72 corresponds to the LED illuminating lamps 2 and 3 shown in FIG. 1 as described above, and generates a forward voltage having the polarity shown in the figure when a load current flows. A capacitor 75 is connected to the LED element group 72 in parallel.

  The inductor 74 has a coupled auxiliary winding 741, one end of the auxiliary winding 741 is connected to the gate of the field effect transistor 71 via the capacitor 76, and the other end is connected to the field effect transistor 71 and the LED. It is connected to the connection point of the element group 72. Then, the DC output that is stepped down is generated across the capacitor 75 via the flywheel diode 77 by the accumulation and release of electromagnetic energy in the inductor 74 accompanying the on / off operation of the field effect transistor 71.

  Further, a negative potential of Vth> Vgs is generated between the source and the gate of the field effect transistor 71 by the output of the auxiliary winding 741 synchronized with the accumulation and release of electromagnetic energy in the inductor 74 to turn off the field effect transistor 71. A self-excited circuit is configured. Note that the flywheel diode 77 here is a normally-on type diode made of GaN, for example.

  A connection point of the resistor element 73 and the inductor 74 is connected to the gate of the field effect transistor 71 via a resistor element 78 which is a current limiting resistor and a normally-off type field effect transistor 80 as a switching element.

  The field effect transistor 80 constitutes an oscillation stop unit 79 as drive control means together with the comparators 81 and 82, the resistance elements 83 and 84, and the power source 85. In this case, the comparator 81 has one input terminal connected to the connection point between the field effect transistor 71 and the LED element group 72, the other input terminal connected to the power supply 85, and the output terminal via the resistance elements 83 and 84. Are connected to the connection point of the resistance element 73 and the inductor 74.

  The comparator 81 is operated as an operational amplifier, and the reference signal Vf for detecting a state in which the forward voltage (load voltage) of the LED element group 72 is lower than the above-mentioned Vth by the setting of the power supply 85 is detected as the resistance element 83, It is generated at 84 connection points. The comparator 82 has one input terminal connected to the connection point between the LED element group 72 and the resistance element 73, the other input terminal connected to the connection point between the resistance elements 83 and 84, and an output terminal connected to the field effect transistor 80. Connected to the gate. The comparator 82 turns on the field effect transistor 80 based on the comparison result between the current flowing through the resistance element 73 and the reference signal Vf.

  Reference numerals 86 and 87 denote diodes constituting a gate voltage clamping circuit that clamps the gate voltage of the field effect transistor 71. In this case, the gate voltage clamp of the field effect transistor 71 is performed using the forward voltage of the LED element group 72.

  Next, the operation of the embodiment configured as described above will be described.

  When the power is turned on by a power switch (not shown), a forward voltage having the polarity shown is generated at both ends of the LED element group 72 via the field effect transistor 71 in the on state. Further, when the field effect transistor 71 is turned on, a current flows through the inductor 74 through the LED element group 72. As a result, electromagnetic energy is accumulated in the inductor 74, and at the same time, an output is generated from the auxiliary winding 721 and input to the gate of the field effect transistor 71 via the capacitor 76. In this case, a negative potential of Vth> Vgs is generated between the source and gate of the field effect transistor 71 by the output of the auxiliary winding 721, and the field effect transistor 71 is turned off.

  In this state, the electromagnetic energy accumulated in the inductor 74 is released, and when the input from the auxiliary winding 721 is lost, the field effect transistor 71 becomes Vth <Vgs and is turned on again.

  Thereafter, the same operation is repeated, and the field effect transistor 71 is turned on and off by the output of the auxiliary winding 741 synchronized with the accumulation and release of electromagnetic energy in the inductor 74. At the same time, a DC output that has been stepped down across the capacitor 75 via the flywheel diode 77 is generated by the accumulation and release of electromagnetic energy by the inductor 74, and the LED element group 72 is turned on by this DC output.

  On the other hand, the comparator 81 is operated as an operational amplifier, and generates a reference signal Vf at a connection point between the resistance elements 83 and 84. In this state, a load current flowing through the resistance element 73 according to the forward voltage (load voltage) of the LED element group 72 is input to the comparator 82. The comparator 82 compares the load current with the reference signal Vf. If it is determined from this comparison result that the load current at this time is smaller than the reference signal Vf, that is, the forward voltage (load voltage) of the LED element group 72 corresponding to the load current is lower than Vth, the output from the comparator 82 Is generated, and the field effect transistor 80 is turned on. Then, the negative potential of the forward voltage of the LED element group 72 is applied between the source and gate of the field effect transistor 71, the field effect transistor 71 is turned off, and self-oscillation is stopped.

  Therefore, even if it does in this way, the effect similar to 1st Embodiment can be acquired. Further, when it is determined that the forward voltage (load voltage) of the LED element group 72 is lower than the Vth voltage, the field effect transistor 71 can be forcibly turned off to stop the self-excited oscillation. Thereby, it is possible to realize circuit protection such as preventing the circuit from becoming uncontrollable due to an abnormal decrease in the forward voltage of the LED element group 72.

  Note that by changing the setting of the reference signal Vf, the self-excited oscillation is stopped when the forward voltage (load voltage) of the LED element group 72 becomes higher than a predetermined forward voltage (load voltage). It can also be.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention in the implementation stage. For example, in the above-described embodiment, an example in which a normally-on type field effect transistor using GaN is described, but other wide band gap semiconductors such as SiC can also be applied. In the above-described embodiment, the example of the LED element is described as the semiconductor light emitting element. However, the present invention can be applied to the case where another semiconductor light emitting element such as a laser diode is used.

  Note that a power supply device (LED lighting device) according to an embodiment has a switching element composed of a normally-on type field effect transistor and a threshold voltage Vth of the gate voltage of the field effect transistor by a forward voltage generated in the semiconductor light emitting element. On the other hand, drive control means that can be turned off by applying a negative potential of Vth> Vgs (gate-source voltage) may be provided.

  In addition, the power supply device according to the embodiment includes drive control means that enables the field effect transistor to be turned off when a forward voltage generated in the semiconductor light emitting element is lower than the threshold value Vth or higher than a predetermined voltage. May be.

  In addition, the power supply apparatus according to the embodiment may include a drive control unit having a normally-on type field effect transistor.

  According to the first to fourth embodiments, a special circuit is not incorporated by using a forward voltage generated in a semiconductor light emitting element to turn off a normally-on type switching element. Miniaturization and low price can be realized.

  In addition, according to the first to fourth embodiments, an appropriate negative potential can be obtained by the forward voltage generated in the semiconductor light emitting element, and the normally-on type field effect transistor can be reliably turned off.

  Furthermore, according to the first to fourth embodiments, the self-excited oscillation by the normally-on type field effect transistor is stopped, and circuit protection can be realized.

(Fifth embodiment)
A fifth mode of the LED lighting device will be described with reference to FIG.

  In this embodiment, the LED lighting device includes a DC power source DC, a chopper CH, a load circuit LC, and a control circuit CC.

  The DC power source DC may have any configuration, but may be configured with, for example, a rectifier circuit DB as a main component, and may include a smoothing circuit including a smoothing capacitor C1 if desired. In this embodiment, the rectifier circuit DB is preferably a bridge-type rectifier circuit, and full-wave rectifies the AC voltage of an AC power supply AC, for example, a commercial AC power supply, to obtain a DC voltage.

  In this embodiment, the chopper CH is constituted by a non-insulated step-down chopper. The power part of the chopper CH, that is, the circuit part through which the power supplied to the load passes is configured to include a normally-on switch Q1, an inductor L1, a free wheel diode D1, and a current detecting impedance element Z1. The power section can be divided into a first circuit A and a second circuit B in terms of circuit operation.

  The first circuit A is a circuit that accumulates electromagnetic energy from the DC power supply DC to the inductor L1, and has a configuration in which a series circuit including a normally-on switch Q1, a load circuit LC, and an inductor L1 is connected to the DC power supply DC. . When the normally-on switch Q1 is turned on, an increased current flows from the DC power source DC, and electromagnetic energy is accumulated in the inductor L1.

  The second circuit B is a circuit that releases electromagnetic energy accumulated in the inductor L1. The second circuit B has a configuration in which a series circuit including a freewheel diode D1 and a load circuit LC is connected to the inductor L1, and a reduced current flows from the inductor L1 when the normally-on switch Q1 is turned off.

  The normally-on switch Q1 is allowed to use various wide gap semiconductors described in the background section, but in this embodiment, a HEMT using a GaN substrate is used. Therefore, the normally-on switch Q1 is a field effect type wide gap semiconductor having a drain, a source, and a gate. The normally-on switch Q1 has a remarkably superior potential compared to a widely used Si semiconductor, and can operate a chopper at an operating frequency of, for example, a GHz class. For this reason, the miniaturization of the inductor L1 can be realized. As a result, the entire LED lighting device can be significantly reduced in size.

  The inductor L1 only needs to have a function of accumulating electromagnetic energy supplied from the DC power source DC and then releasing it, so that it is not necessary to provide a secondary winding as in the prior art. . For this reason, it is possible to simplify the structure of the inductor L1 and contribute to its miniaturization.

  The freewheel diode D1 is a means for providing a current path, that is, a second circuit B, for discharging and regenerating electromagnetic energy stored in the inductor L1. As the freewheel diode D1, a switching diode such as a Schottky barrier diode or a PIN diode can be used according to the operating frequency of the chopper CH.

  The current detecting impedance element Z1 is inserted into a position on the circuit through which both an increasing current and a decreasing current flow, that is, a line portion shared by the first circuit A and the second circuit B, and detects each of the currents. It is. For example, a resistor having a small resistance value is used.

  In the case of the step-up chopper, the chopper CH includes a first circuit A in which a series circuit of the inductor L1 and the normally-on switch Q1 is connected to the DC power source DC, and a series circuit of the inductor L1, the freewheel diode D1, and the load circuit LC. A second circuit B connected to the DC power source DC can be used. The step-up / down chopper is as described above.

  The load circuit LC is constituted by a parallel circuit of a light emitting diode LED and an output capacitor C2, and is connected to a position on the circuit through which both an increase current and a decrease current flow. Note that the light emitting diode LED is composed of a single forward or a plurality of series connected in series with respect to the current.

  The control circuit CC includes a control switch CS and matching means MC, and operates by receiving an appropriate control power supply to control on / off of the normally-on switch Q1. In this embodiment, control power is supplied to the control circuit CC from both ends of the load circuit LC.

  The control switch CS is means for switching the normally-on switch Q1 on and off. That is, if the gate of normally-on switch Q1 is connected to the connection point of impedance element Z1 and inductor L1 by turning on control switch CS, a negative voltage is applied to the gate of normally-on switch Q1 with respect to the source. Therefore, the normally-on switch Q1 is turned off. Further, when the control switch CS is turned off and the gate of the normally-on switch Q1 is released from the connection to the connection point between the impedance element Z1 and the inductor L1, or is at the same potential as the source, the normally-on switch Q1 is turned on.

  Matching means MC is interposed between impedance element Z1 and control switch CS, and turns on control switch CS when the increased current reaches the first predetermined value. Further, the control switch CS is turned off when the reduced current reaches the second predetermined value.

  Therefore, when the terminal voltage of the impedance element Z1 reaches the first predetermined value when the increased current is flowing, the matching unit MC turns on the control switch CS, so that the normally-on switch Q1 is turned off. Further, when the terminal voltage of the impedance element Z1 reaches the second predetermined value while the reduced current is flowing, the matching unit MC turns off the control switch CS, so that the normally-on switch Q1 is turned on.

  Next, circuit operation will be described.

  When the DC power source DC is turned on, the normally-on switch Q1 of the chopper CH is turned on, current flows out from the DC power source DC in the first circuit A, and the current increases linearly. This is an increased current, and electromagnetic energy is accumulated in the inductor L1. When the increased current begins to flow through the first circuit A, the terminal voltage of the impedance means Z1 increases in proportion to the increased current. When the terminal voltage reaches the first predetermined value, the matching means MC turns on the control switch CS.

  When the control switch CS is turned on, the gate of the normally on switch Q1 becomes a negative voltage, so that the normally on switch Q1 is turned off and the increased current is cut off. As a result, the electromagnetic energy accumulated in the inductor L1 is released, and a current begins to flow in the first circuit B, and the current decreases linearly. This is the reduced current. When the reduced current reaches the second predetermined value, the matching means MC turns off the control switch CS.

  When the control switch CS is turned off, the application of the negative voltage to the gate of the normally-on switch Q1 is released, so the normally-on switch Q1 is turned on and the increased current starts flowing again. Thereafter, the above circuit operation is repeated to continue the DC-DC conversion operation.

(Sixth embodiment)
A sixth embodiment of the LED lighting device will be described with reference to FIG.

  In this embodiment, the control circuit CC is different from the fifth embodiment. In the figure, the same parts as those in FIG.

  In this embodiment, the control circuit CC is composed of a P-type FET 1 and an N-type FET 2 to which a control switch CS is connected in parallel. The connection end of the drain of the P-type FET 1 and the source of the N-type FET 2 is connected to the gate of the normally-on switch Q1.

  The matching circuit MC is configured by a hysteresis comparator CPh. The hysteresis comparator CPh has an inverting input terminal connected to one end of the impedance means Z1 on the load circuit LC side, a non-inverting input terminal connected to the reference potential E, and an output terminal connected to the gates of the P-type FET1 and the N-type FET2. Connected. Further, a feedback resistor R1 whose resistance value has been adjusted in advance is connected between the non-inverting input terminal and the output terminal. The reference potential E is formed at the connection point of a voltage divider VD composed of resistors R2 and R3 connected in parallel to the series part of the load circuit LC and impedance means Z1.

  Thus, when the normally-on switch Q1 is turned on and the increased current IU is flowing in the impedance means Z1, when the terminal voltage of the impedance means Z1 reaches the first predetermined value, the hysteresis comparator CPh receives the inverting input terminal. A positive first predetermined value voltage is input, and a negative maximum output voltage is output to the output terminal. Since this negative maximum output voltage is applied to the gate of the P-type FET 1 of the control switch CS, the P-type FET 1 is turned on. At this time, the N-type FET 2 remains off.

When the P-type FET 1 is turned on, the normally-on switch Q1 has a negative potential, so the normally-on switch Q1 is turned off and the increased current _IU is cut off. Along with this, a reduced current _ID flows from the inductor L1. Since the terminal voltage of the impedance means Z1 when the reduced current _ID is flowing is input to the inverting input terminal of the hysteresis comparator CPh subsequently to the terminal voltage of the increased current, when the value reaches the second predetermined value, This time, the maximum positive voltage is output from the output terminal of the hysteresis comparator CPh. As a result, the P-type FET 1 is turned off and the N-type FET 2 is turned on.

  As a result of turning off the P-type FET 1 and turning on the N-type FET 2, the normally-on switch Q 1 is turned on, so that an increased current flows again to the load circuit LC. Thereafter, the above operation is repeated to perform the chopper operation.

Next, with reference to FIG. 9, the relationship between the current and voltage waveform of each part in the sixth embodiment will be described. That, (a) shows the increased current _{I U} of the waveform of FIG. 9, (b) the waveform of the decreased current _{I D,} (c) is a waveform of the terminal voltage _{V Z1} impedance means, (d) the voltage of the inductor _{V L1} (E) is a waveform of the normally-on switch gate voltage V _GS , and the time axes are aligned. Incidentally, in the figure, it corresponds to when the peak value of the current increases I _U reaches a first predetermined value. Further, this corresponds to the case where the zero value of the decrease current _ID reaches the second predetermined value.

  The current waveform diagram of FIG. 9 is an ideal waveform when there is no delay in control, but when a delay that cannot be ignored occurs in the control when the increased current is cut off, the control delay is delayed from the peak value. There is a first predetermined value at a position lower by the corresponding value. In addition, when a delay that cannot be ignored occurs in the control when the reduced current reaches the second predetermined value, a current cutoff time corresponding to the control delay is generated between the reduced current and the next increased current. Occurs.

(Seventh embodiment)
A seventh embodiment of the LED lighting device will be described with reference to FIG.

  In the present embodiment, the control circuit CC is different from the fifth and sixth embodiments. In the figure, the same parts as those in FIG.

  That is, the control switch CS is mainly composed of the bipolar transistor Q2. In the bipolar transistor Q2, the collector is connected to the gate of the normally-on switch Q1, the source is connected to the source of the normally-on switch Q1 via the control power supply Vdd consisting of a dropper, and the emitter is connected to the connection point between the inductor L1 and the impedance means Z1. is doing.

  The matching means MC is mainly composed of a bipolar transistor Q3 and resistors R4 and R5. The collector of the bipolar transistor Q3 is connected to the base of the bipolar transistor Q2 of the control switch CS via the resistor R4, the emitter is connected to the connection point of the inductor L1 and the impedance means Z1, and the base is connected to the bipolar transistor via the resistor R6. Connected to the collector of Q2. A series circuit of resistors R5 and R4 and a collector / emitter of the bipolar transistor Q3 is connected in parallel to the impedance means Z1.

  Thus, when the normally-on switch Q1 is turned on and an increasing current is flowing, the bipolar transistor Q2 of the control switch CS is turned off and the bipolar transistor Q3 of the matching means MC is turned on. Therefore, the terminal voltage of the impedance means Z1 is divided by the series circuit of the resistor R4 and the resistor R5, and the voltage across the resistor R4 is applied between the base and emitter of the bipolar transistor Q2.

  Therefore, by adjusting the values of the resistors R4 and R5 in advance and setting the value of the resistor R4 to be relatively small, the bipolar transistor Q2 is at a level before the increased current reaches the first predetermined value. Can be configured to be turned off. However, when the increased current reaches the first predetermined value, the bipolar transistor Q2 is turned on and a negative voltage is applied to the gate of the normally-on switch Q1, so that the normally-on switch Q1 is turned off and the increased current is cut off. Is done.

  When the bipolar transistor Q2 is turned on, the bipolar transistor Q3 is turned off. Therefore, when the normally-on switch Q1 is turned off and a decreasing current flows, the bipolar transistor is not divided into the terminal voltage of the impedance means Z1. The voltage is applied to Q2, and the bipolar transistor Q2 continues to be on. However, when the terminal voltage of the impedance means Z1 decreases and reaches the second predetermined value, the bipolar transistor Q2 is turned off without being able to maintain the on state. As a result, the normally-on switch Q1 is turned on again. Thereafter, the above circuit operation is repeated and the chopper operation is continued.

  In the above embodiment, the chopper includes various choppers such as a step-down chopper, a step-up chopper, and a step-up / step-down chopper. The step-up / step-down chopper is obtained by sequentially connecting a step-up chopper and a step-down chopper. In each of the above choppers, when the normally-on switch is turned on, the increased current flowing from the DC power source flows into the inductor, and when it is turned off, the electromagnetic energy accumulated in the inductor is released and the decreased current flows, and the chopper operation is performed. It is common to do.

  In the above embodiment, the control circuit includes a control switch and matching means.

  The control switch includes at least a switch that switches the normally-on switch from the on state to the off state. Note that it is allowed to include a second switch for switching the normally-on switch from the off state to the on state if desired. In this case, the switch that switches the normally-on switch from the on state to the off state is the first switch.

  The matching means is interposed between the impedance means and the control switch, and when the increased current flows through the impedance means, the matching switch operates the control switch when the terminal voltage of the impedance means reaches the first predetermined value and is normally on. Turn off the switch. In the case where the reduced current flows, the normally on switch is turned on by controlling the control switch when the terminal voltage of the impedance means reaches the second predetermined value. Note that the second predetermined value is lower than the first predetermined value.

  The matching means only needs to have the above-described function, and the remaining configuration is not particularly limited. However, the matching means can preferably be constituted by a hysteresis comparator. The matching means includes a first detection means for directly detecting the terminal voltage of the impedance means and a second detection means for detecting via the voltage divider, and interlocks when the control switch turns off the normally-on switch. The second detection unit may be switched to the first detection unit.

  Thus, when the normally-on switch is on, an increased current flows from the DC power source to the inductor. When the terminal voltage of the impedance means reaches the first predetermined value, the control switch is turned on via the matching means. Since a negative voltage is applied to the gate of the normally-on switch, the normally-on switch is turned off and the increased current is cut off. Along with this, the electromagnetic energy stored in the inductor is released and a reduced current flows from the inductor, and the control switch is turned off via the matching means to cancel application of the negative voltage to the gate of the normally-on switch. The mullion switch turns on. Thereafter, the above-described circuit operation is repeated to perform the chopper operation.

  Since the load circuit is connected at a position on the circuit where both an increase current and a decrease current accompanying the chopper operation flow, DC-DC voltage conversion is performed, and the light emitting diode of the load connected to the output terminal converts the converted voltage. Lights under constant current control. Note that the output capacitor connected in parallel with the light emitting diode of the load circuit acts to bypass the high frequency component contained in the output of the chopper from the light emitting diode. As a result, the light emitting diode is turned on by the smoothed direct current.

  In the above embodiment, the supply of the control power to the control circuit is not particularly limited, but is preferably as follows. That is, a control power supply is obtained from the high voltage side of the load circuit or normally-on switch. In the aspect of obtaining the control power supply from the load circuit, since a DC voltage smoothed by the output capacitor is generated in the load circuit, a voltage higher than the gate threshold voltage of the normally-on switch is obtained from the load circuit to obtain the control power supply. The circuit configuration of the control power supply can be simplified. Further, in the aspect in which the control power supply is obtained from the high voltage side of the normally-on switch, for example, a voltage higher than the gate threshold voltage of the normally-on switch can be obtained from the drain side of the normally-on switch via the dropper.

  In the above-described embodiment, the lighting device is meant to include all devices using light emitting diodes as light sources. Therefore, it is allowed to be a lighting fixture, a display device, a sign device, and the like. The illuminating device main body means a remaining portion obtained by removing the LED lighting device from the illuminating device.

  According to the fifth to seventh embodiments described above, the normally-on switch is used as the main switching element of the chopper, and the normally-on switch is controlled to be in the off state by applying a negative voltage to the gate of the normally-on switch at least when being on. And a switch that controls application of the normally-on switch to an on state by canceling the application of a negative voltage to the gate of the normally-on switch when the switch is off, and when an increased current flows between the impedance element and the control switch. The control switch is turned on when the terminal voltage of the impedance element reaches the first predetermined value, and is controlled when the terminal voltage of the impedance element reaches a second predetermined value lower than the first predetermined value when the reduced current is flowing. By providing a control circuit that turns off the switch, a secondary winding is provided on the inductor. It becomes simple circuit configuration without Rukoto, yet can provide a lighting device which an IC is provided with easy chopper and which together with good properties.

(Eighth embodiment)
An eighth embodiment is shown in FIG. The LED lighting device includes a DC power source DC, a chopper CH, and a load circuit LC.

  The DC power source DC is means for inputting a DC voltage before conversion to a chopper CH described later. Any configuration may be used as long as it outputs a DC voltage. For example, a rectifier circuit DB is mainly used, and a smoothing circuit including a smoothing capacitor can be provided as desired. In this embodiment, the rectifier circuit DB is preferably a bridge-type rectifier circuit, and full-wave rectifies the AC voltage of an AC power supply AC, for example, a commercial AC power supply, to obtain a DC voltage.

  In this embodiment, the chopper CH includes DC input terminals t1 and t2 and DC output terminals t3 and t4. The chopper CH includes any one of various known choppers such as a step-down chopper, a step-up chopper, and a step-up / step-down chopper. The chopper CH includes the switching element Q11, the constant current means CCM, the inductor L11, the diode D11, and the drive winding DW as a common configuration in any of the above configurations.

  Switching element Q11 may be either a normally-off switch or a normally-on switch. The constant current means CCM may be of a type in which the constant current value is fixedly set in advance or may be variable. One end of the inductor L11 is connected to the drive winding DW. The drive winding DW is magnetically coupled to the inductor L11, induces a voltage proportional to the terminal voltage of the inductor L11, and drives the switching element Q11 by applying it to the control terminal of the switching element Q11.

  The chopper CH has a pair of input terminals t1 and t2 and a pair of output terminals t3 and t4, and the internal circuit can be divided into a third circuit and a fourth circuit in terms of circuit operation. The third circuit is a circuit that accumulates electromagnetic energy in the inductor L11 by flowing an increasing current from the DC power source DC. In the case of a step-down chopper, the switching element Q11, constant current means, inductor L11, and load circuit LC are connected. The series circuit including is provided with the structure connected to DC power supply DC. When the switching element Q11 is turned on, a current that increases from the DC power source DC flows, and electromagnetic energy is accumulated in the inductor L11.

  The fourth circuit is a circuit that discharges the electromagnetic energy accumulated in the inductor L11 and flows a current that decreases. In the case of a step-down chopper, a series circuit including a diode D11 and a load circuit LC described later is connected to the inductor L11. A current that decreases from the inductor L11 flows when the switching element Q11 is turned off.

  In the case of the step-up chopper, the chopper CH is a third circuit in which a series circuit of the inductor L11, the switching element Q11 and the constant current means CCM is connected to the DC power source DC, and a series circuit of the inductor L11, the diode D11 and the load circuit LC. Includes a fourth circuit connected to the DC power source DC. The step-up / down chopper is as described above.

The load circuit LC includes an output capacitor that includes a light emitting diode as a load and bypasses a high frequency component. In the case of a step-down chopper, the load circuit LC is located at a position on the circuit where both an increasing current and a decreasing current flow. It is connected. In the case of the step-up type, it is connected to a position on the circuit through which a decreasing current flows. The light-emitting diode LED is composed of a single forward current or a plurality of serially connected currents flowing through the output end of the chopper.

  The ninth to twelfth embodiments will be described below with reference to FIGS. In addition, in each figure, the same code | symbol is attached | subjected about the part same as FIG. 11, and description is abbreviate | omitted.

(Ninth embodiment)
(Ninth Embodiment) will be described.

  A ninth embodiment is shown in FIG. In this embodiment, a GaN-HEMT is used for the switching element Q11, a constant current diode is used for the constant current means CCM, and an inductor L11 is connected between the constant current means CCM and the load circuit LC. In the figure, the same parts as those in FIG. Reference numeral C11 is a high-frequency bypass capacitor connected between the input ends t1 and t2 of the chopper CH. Reference numeral C12 is a coupling capacitor inserted between the drive winding DW and the control terminal of the switching element Q11. Reference numeral C is a third circuit, and reference numeral D is a fourth circuit. Reference symbol LED of the load circuit LC is a light emitting diode, and C13 is an output capacitor.

  Next, the circuit operation in the ninth embodiment will be described with reference to FIGS.

When the DC power source DC is turned on, the switching element Q11 of the chopper CH is turned on, so that a current flows out from the DC power source DC through the switching element Q11 and the constant current means CCM in the third circuit C. Increases linearly. As a result, electromagnetic energy is accumulated in the inductor L11. Note that the gate-source voltage V _GS of the switching element Q11 is 0 during the period when the switching element Q11 is on. When the increasing current reaches the constant current value of the constant current means CCM, the increasing tendency of the current is stopped and held at the constant current. Note that while the increasing current flows through the inductor L11, the terminal voltage of the inductor L11 is positive as shown in FIG.

When the increasing current reaches the constant current value of the constant current means CCM, the current flowing through the inductor L11 tends to increase further, so that the voltage V _CCM of the constant current means CCM is pulsed as shown in FIG. Become bigger. Along with this, the source potential of the switching element Q11 becomes higher than the potential of the control terminal (gate), and as a result, the control terminal becomes relatively clearly a negative potential, so that the switching element Q11 is turned off. Therefore, current _{I U} to increase flow into the inductor L11 is cut off by the off of the switching element Q11 as illustrated in FIG. 13 (b).

  At the same time when the switching element Q11 is turned off, the electromagnetic energy stored in the inductor L11 starts to be released, and a current that decreases as shown in FIG. While the decreasing current flows, the voltage polarity of the inductor L11 is inverted as shown in (e) of FIG. 13 to become negative, and the control terminal of the switching element Q11 is negative in the drive winding DW. A voltage that becomes a potential is induced. In this case, since a negative voltage is applied between the gate and source of the switching element Q11 via the constant current means CCM as shown in FIG. 13 (f), the switching element Q11 is maintained in the OFF state.

  When the decreasing current flowing through the third circuit C becomes 0, the negative voltage applied to the control terminal of the switching element Q11 is not induced, and at the same time, the control terminal is shown in FIG. Thus, a positive voltage is induced in the drive winding DW. As a result, the switching element Q11 is turned on again, and the circuit operation similar to that described above is repeated thereafter.

As is apparent from the above circuit operation, the chopper CH performs a step-down chopper operation, and an output current I _{O in} which an increasing current and a decreasing current alternately flow in the load circuit LC connected between the output terminals t3 and t4. Is formed as shown in FIG. 13 (d), and the light emitting diode LED is turned on by the direct current component, and the output capacitor C4 bypasses the high frequency component.

(Tenth embodiment)
The (tenth embodiment) will be described.

  A tenth embodiment is shown in FIG. In this embodiment, the constant current means CCM is a GaN-HEMT, and the inductor L11 is connected to a position where the load circuit LC is interposed between the constant current means CCM.

Further, the constant current means CCM makes the constant current value variable by making the gate potential variable by using the adjustable potential source E. In the figure, a symbol ZD1 is a diode for clamping the switching element Q11 so that the gate-source voltage V _GS does not become 0.6 V or more.

  Furthermore, in this embodiment, the switching element Q11, the constant current means CCM, and the diode D11 forming a series connection body are configured as an integrated circuit IC. The integrated circuit IC includes first to fifth external terminals P1 to P5. The first external terminal P1 is derived from the drain of the switching element Q11. The second external terminal P2 is derived from the cathode of the diode D11. The third external terminal P3 is derived from the connection point between the source of the constant current means CCM and the anode of the diode D11. The fourth external terminal P4 is derived from the gate of the switching element Q11. The fifth external terminal P5 is derived from the gate of the constant current means CCM.

  That is, in the integrated circuit IC, the first and second main terminals are derived from the main terminals of the semiconductor elements located at both ends of the series connection body composed of the three power semiconductor elements of the chopper, and the middle of the series connection body. The third external terminal is led out from the main terminal of the connection portion, and the fourth and fifth external terminals are led out from the control terminal of the switching element Q11 and the constant current means CCM. Therefore, the first to third external terminals are power systems, and the fourth and fifth external terminals are control systems.

  Thus, in the tenth embodiment, since the constant current means CCM is composed of GaN-HEMT as with the switching element Q11, the high-speed switching characteristic at a high frequency of 10 MHz or more is further improved. However, if the diode D11 is also formed of a GaN substrate if desired, an integrated integrated circuit can be formed using a GaN substrate, and extremely high-speed switching can be achieved and a downsized chopper can be formed. Becomes easier.

  Further, since the constant current value is variable by using the adjustable potential source E1, it becomes easy to set a desired load current, and if the adjustable potential source E1 is feedback-controlled with respect to power supply voltage fluctuations. In addition, fluctuations in the light output of the light emitting diode with respect to fluctuations in the power supply voltage can be suppressed. Furthermore, the voltage drop of the constant current means CCM and the load circuit LC is added to the negative voltage of the drive winding DW applied to the control terminal of the switching element Q11.

(Eleventh embodiment)
(Eleventh embodiment) will be described.

The eleventh embodiment is shown in FIG. Note that the same parts as those in FIG. In this embodiment, the constant current means CCM is constituted by a current mirror constant current circuit using transistors Q12 and Q13. In the current mirror constant current circuit, the series circuit of the transistor Q12 and the resistor R11 is inserted in series with the switching element Q11, the base of the transistor Q13 is connected to the base of the transistor Q12, and the reverse bias power supply E2 is reverse polarity to the emitter. A DC power supply E3 is connected to a series circuit of a collector and a bias power supply E2. Furthermore, the collector and base of transistor Q13 are directly connected by a conductor.

In addition, a pair of Zener diodes ZD1 and ZD2 are connected in parallel with opposite polarities between the control terminal of the switching element Q11 and the position across the constant current means CCM to form a clamp circuit. The Zener diode ZD1 has a Zener voltage of −12V, and the Zener diode ZD2 has a Zener voltage of + 0.7V, so that an excessive V _GS is not applied to the switching element Q11.

  Thus, according to the eleventh embodiment, the constant current value flowing through the transistor Q12 can be controlled as desired by the DC voltage connected to the transistor Q13, and the voltage generated when the constant current value is reached increases. For this reason, it is not necessary to use the voltage of the light emitting diode LED of the load.

  Further, since the DC power source E2 is used to control the constant current means CCM constant current value, a transistor capable of high speed control is not required. Further, if the constant current means CCM is turned off synchronously when turning off the switching element Q11, the switching element Q11 can be substantially normally off. Furthermore, it is possible to integrate the semiconductor component parts of the switching element Q11, the constant current means CCM and the diode D11 on a GaN-based chip as desired.

(Twelfth embodiment)
(Twelfth embodiment) will be described.

  A twelfth embodiment is shown in FIGS. 16 and 17. FIG. 16 is a schematic diagram of an integrated circuit module according to a fifth embodiment for implementing the LED lighting device. FIG. 17 is a schematic partially enlarged and partially sectional perspective view of a planar coil structure.

  In this embodiment, in some or a plurality of the eighth to eleventh embodiments, an IC is formed by integrating semiconductor components, coil components, capacitor components, and external terminals of the LED lighting device. That is, the remaining circuit components excluding the light emitting diode LED of the LED lighting device are composed of a planar coil structure L, a planar capacitor structure C, a GaN chip G, a wiring formation body W, a terminal formation body T, and a substrate structure B. Each planar structure is divided and formed. These planar structures are laminated together, and the structures are connected using means such as through holes to form an integrated circuit module IC ′. The integrated circuit module IC of the illustrated example is configured by the following planar structures.

  As shown in FIG. 17, the planar coil structure L is formed by winding the inductor L <b> 11 and the drive winding DW by winding a flat coil wire in a spiral shape on a plane. They are held so as to be in a moderately spaced state, and the inside and the periphery are covered with the magnetic layer M. Thereby, the planar coil structure L is configured in a planar shape as a whole.

  And one end of the inductor L11 and the drive winding DW is located in the center part of the coil, and comprises the terminal part t. Then, a through hole h is formed at the center of the terminal portion t, one terminal conductor of a constant current means portion of a GaN chip G described later is inserted into the through hole h, and a conductor is injected into the inside, The inductor L11, the drive winding DW, and the connection conductor of the GaN chip G are connected together. The magnetic layer M is made of, for example, ceramics or plastics in which ferrite fine particles are dispersed, as shown in a cross-sectional view in which a part of FIG. 17 is enlarged to the right side of the drawing.

  The planar capacitor structure C is a planar structure in which a plurality of capacitors each including a pair of electrode bodies each sandwiching a thin dielectric film is assembled.

  The GaN chip G is a planar structure in which a switching element Q11, a constant current means CCM, and a diode D11 are formed on a GaN-based semiconductor substrate.

  The wiring formation body W is a planar structure that connects the planar coil structure L, the planar capacitor structure C, and the GaN chip G to the terminal formation body T described later as required.

The terminal formation body T is interposed between the wiring formation body W and a substrate structure B to be described later, and connects them. The substrate structure B includes an external terminal TE and external attachment means (not shown). Each planar structure described is integrally supported and modularized. The external terminal TE is an output terminal for connecting the input terminal of the LED lighting device and the light emitting diode LED.

  Thus, this embodiment is suitable for an LED lighting device that operates at a high frequency of 10 MHz or more, and the external terminals TE arranged on the substrate structure B are all DC, and only DC input / output is possible. Therefore, the operation is stable and a significant downsizing can be realized. For this reason, it becomes possible to arrange | position an LED lighting device between the light emitting diodes of an illuminating device, and it contributes to remarkable miniaturization of an illuminating device.

  In addition, the LED lighting device which concerns on one Embodiment is provided with the serial connection body of a switching element, a constant current means, and a diode. The series connection body includes first and second external terminals derived from a pair of main terminals located at both ends thereof, and a third external body derived from a main terminal located at an intermediate connection portion of the series connection body. An integrated circuit having a terminal and fourth and fifth external terminals derived from the switching element and the control terminal of the constant current means;

  In the above embodiment, the “chopper” is a concept including various choppers such as a step-down chopper, a step-up chopper, and a step-up / step-down chopper. The step-up / step-down chopper is obtained by sequentially connecting a step-up chopper and a step-down chopper. In each of the above choppers, an increase current flows from the DC power source to the inductor by turning on the switching element, and a decrease current flows through the diode by the electromagnetic energy accumulated in the inductor by turning off the switching element. Is common in that the DC power supply voltage is DC-DC converted and output to the output terminal.

  The switching element may be either a normally-on switch or a normally-off switch. When a wide bandgap semiconductor such as GaN-HEMT is used as the switching element, the switching characteristics at high frequency of MHz or higher, for example, 10 MHz or higher are remarkably improved, the switching loss is reduced, and the inductor is also downsized. Can be greatly reduced in size.

  In addition, in the case of a switching element using a wide band gap semiconductor, a device having a normally-on characteristic is easier to obtain and lower in cost, but a device having a normally-off characteristic is also possible. Also good. In addition, it is preferable to use a normally-on switch having a negative switching threshold value because an off control using a drive winding magnetically coupled to the inductor is facilitated.

  The constant current means is a circuit means having a constant current characteristic. For example, various constant current circuits using a constant current diode, a junction FET, a three-terminal regulator, and a transistor can be used. The constant current circuit using a transistor is allowed to be a known constant current circuit using a monolithic or bilithic transistor. Moreover, GaN-HEMT which is a kind of junction FET can be used as a constant current means. Since this switching element is excellent in switching characteristics at a high frequency of 10 MHz or more, it is convenient for performing high-speed switching.

  The constant current means is interposed in series with the switching element in the first circuit in which current flows through the inductor when the switching element is on. The constant current means is also interposed in the drive circuit for the switch element including the drive winding for driving the switching element. By having these configurations, the increasing current flowing through the constant current means reaches a constant current value, and when further increasing, the voltage of the constant current means rapidly increases. Due to the rise in voltage, the potential of the main terminal (eg, source) incorporated in the switching element drive circuit can be made relatively higher than the potential of the control terminal (eg, gate). As a result, since the potential of the control terminal becomes lower than the threshold value of the switching element, the switching element can be turned off. This circuit operation becomes easier and more reliable when the switching element is a normally-on switch and the threshold value is negative, but it is also effective for a normally-off switch.

  In addition, the switching element and the constant current means can be directly connected in series. In this case, it is easy to integrate the switching element and the constant current means on a common semiconductor chip, for example, a GaN chip. become. In this case, one main terminal of the switching element, for example, the drain, two terminals of the power system consisting of the main terminal on the other end side with respect to the switching element of the constant current means, and control of each of the switching element and the constant current means The switching element and the constant current means can be constituted by an IC module having a terminal structure, for example, two control system terminals composed of gates, so that the single component can be further miniaturized. be able to.

  The inductor stores electromagnetic energy inside when an increasing current flows from the DC power source to the first circuit via the switching element and the constant current means. Further, since the inductor releases the electromagnetic energy stored when the switching element is turned off, a current that decreases at that time flows to the second circuit.

  Further, when the chopper is operated at a high frequency of 10 MHz or higher, the inductor and the drive winding magnetically coupled to the inductor have a planar coil structure, and the capacitor has a planar structure, which is convenient for the integrated circuit of the chopper, Highly reliable operation can be obtained. In other words, a planar coil inductor and drive winding, a planar capacitor, a switching element, a constant current means, and a semiconductor chip on which semiconductor components such as a diode to be described later are stacked are integrated to be integrated as a whole. A circuit module can be constructed. As a result, the LED lighting device can be significantly reduced in size. Along with this, the distance between the drive coil and the switch is minimized, so that the generation of parasitic inductance and capacitance that are unnecessary and harmful to noise generation can be minimized, and the chopper operation. Improves stability and reliability.

  The diode provides a second circuit that is a path through which a decreasing current flows out of the inductor. When a wide bandgap semiconductor, for example, a GaN-based diode is used as the diode, even higher speed switching is possible. In this case, it becomes easy to configure the diode as an integrated circuit of the semiconductor element together with the switching element and the constant current means. This integrated circuit has three main terminals of a power system comprising a main terminal at one end, a main terminal at the other end, and a main terminal at an intermediate connection point in a series connection body of a switching element, a constant current means and a diode. And it has a structure provided with five external terminals for convenience with two control terminals for controlling the switching element and the constant current means, respectively.

  When the chopper is configured using the integrated circuit, the whole is further reduced in size and it becomes easy to perform high-speed switching.

  The drive winding is a winding magnetically coupled to the inductor and controls the switching element. That is, when the increasing current flowing in the inductor when the switching element is on reaches the constant current value of the constant current means and the switching element is turned off, a large voltage is generated, so the main terminal (source) of the switching element is controlled. Since it becomes higher than the terminal and the control terminal becomes relatively negative and falls below the threshold value, the switching element is maintained in the OFF state.

  According to the above eighth to twelfth embodiments, the constant current means when the increasing current flowing from the DC power source to the inductor via the constant current means reaches the constant current value of the constant current means when the switching element is turned on. Since the switching element is turned off by the voltage generated in the capacitor, the impedance element such as a resistance element for detecting the current flowing through the inductor and a control circuit for turning off the switching element when the voltage drop reaches a preset threshold value are configured. Without providing a current feedback type feedback circuit, when the increasing current reaches a predetermined value, the switching element can be turned off with a simple configuration and the chopper operation is performed, which simplifies the circuit configuration. In addition, an LED lighting device including a chopper that can be easily integrated and miniaturized can be provided.

  Furthermore, the inductor and the drive winding have a planar coil structure, and an integrated circuit in which at least the switching element and the diode are stacked on at least one surface of the planar coil structure is configured. Since the generation of parasitic inductance and parasitic capacitance that are unnecessary and harmful to noise generation can be minimized, the stability and reliability of the chopper operation is improved.

Furthermore, if the switching element, the constant current means, and the diode are configured as an integrated circuit having five external terminals, the entire chopper can be further miniaturized and high-speed switching can be easily performed.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Appliance main body, 2 ... LED lighting, 4 ... shade, 10 ... alternating current power supply, 11 ... full wave rectifier circuit, 12 ... capacitor | condenser, 13 ... field effect transistor, 14 ... semiconductor light emitting element, 15 ... resistance element, 16 ... Inductor, 17 ... Power source, 18 ... Field effect transistor, 19 ... Diode, 20 ... Capacitor, 21 ... Diode, 22 ... Flywheel diode, 23 ... Comparator, 24 ... Diode, 31 ... LED element group, 32-33 ... Field effect Transistors 32a to 33a ... diodes 34 ... capacitors 35 ... inductors 36 ... capacitors 37 ... diodes 38 ... capacitors 39 ... first drive source 40 ... diodes 41 ... capacitors 42 ... second drives Source 43 ... Field effect transistor 43a ... Diode 44 ... Capacitor 46 ... Current source, 47 ... Field effect transistor, 48 ... Capacitor, 49 ... Zener diode, 51-54 ... Field effect transistor, 51a-54a ... Diode, 55 ... LED element group, 56-59 ... Diode, 60 ... Capacitor, 61 ... Field effect transistor, 62 ... Field effect transistor, 63 ... Driving source, 64 ... Switch drive unit, 65 ... Inductor, 71 ... Field effect transistor, 72 ... LED element group, 73 ... Resistance element, 74 ... Inductor, 75-76 ... Capacitor, 77... Flywheel diode, 78... Resistive element, 79. Oscillation stop, 80... Field effect transistor, 81. Auxiliary winding, 741... Auxiliary winding.

Claims (6)

Output generating means having at least one normally-on type switching element and generating a DC output by an on / off operation of the switching element;
A semiconductor light emitting element which is turned on by a direct current output generated by the output generating means;
Drive control means for turning off the switching element using a current flowing through the semiconductor light emitting element;
LED lighting device comprising:   The LED lighting device according to claim 1, wherein the drive control unit turns off the switching element by a forward voltage generated in the semiconductor light emitting element.   The switching element is a normally-on type field effect transistor, and the drive control means is configured such that Vth> Vgs (with respect to a threshold voltage Vth of the gate voltage of the field effect transistor by a forward voltage generated in the semiconductor light emitting element. 3. The LED lighting device according to claim 2, wherein a negative potential of the gate-source voltage) is applied to enable the LED lighting device.   The drive control means enables the field effect transistor to be turned off when a forward voltage generated in the semiconductor light emitting element is lower than the threshold value Vth or higher than a predetermined voltage. LED lighting device of description.   4. The LED lighting device according to claim 2, wherein the drive control means includes a normally-on type field effect transistor. An LED lighting device according to claim 1;
An instrument body having the LED lighting device;
A lighting fixture comprising:

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