JP6614532B2 - Lighting device and lighting fixture including the same - Google Patents

Description

  The present invention relates to a lighting device and a lighting fixture including the same, and more particularly to a lighting device and a lighting fixture for lighting a solid light source.

  Conventionally, there has been an LED lighting device for lighting an LED (see, for example, Patent Document 1). The LED lighting device of Patent Document 1 includes a DC conversion circuit including a step-up chopper and a step-down chopper, and a control unit that controls switching elements respectively provided in the step-up chopper and the step-down chopper. The control means is configured using a semiconductor device such as a microcomputer or IC.

JP 2011-9383 A

  When the power supply to the LED lighting device is cut off in order to turn off the LED, if the voltage for operating the control means decreases, the operation of the control means becomes unstable, and the output of the LED lighting device becomes There was a possibility of becoming unstable.

  This invention is made | formed in view of the said subject, and it aims at providing the lighting device which reduced the possibility that operation | movement will become unstable at the time of light extinction, and a lighting fixture provided with the same.

  A lighting device of one embodiment of the present invention includes a lighting circuit, a control circuit, a first power supply circuit, a current-voltage conversion unit, and a second power supply circuit. The lighting circuit converts an input voltage from a power source into a DC output voltage and supplies it to a light source. The control circuit controls the output of the lighting circuit. The first power supply circuit generates a first DC voltage that becomes a power supply voltage of the control circuit from an input voltage from the power supply. The current-voltage conversion unit generates a voltage having a voltage value corresponding to the current value of the output current of the lighting circuit. The second power supply circuit generates an offset voltage by dividing the second DC voltage obtained by stepping down the first DC voltage. The second DC voltage is set to a voltage lower than a minimum operating voltage that is a lower limit value of a power supply voltage at which the control circuit can operate. The control circuit controls the output of the lighting circuit based on a voltage obtained by adding the offset voltage to the voltage generated by the current-voltage converter. When the first DC voltage generated by the first power supply circuit falls below the minimum operating voltage, the control circuit stops operating.

  The lighting fixture of 1 aspect of this invention is equipped with the said lighting device and the main body holding the said lighting device.

  According to the present invention, it is possible to reduce the possibility that the operation becomes unstable when the light is turned off.

FIG. 1 is a circuit diagram of a lighting device according to Embodiment 1 of the present invention. FIG. 2 is a waveform diagram of each part of the lighting device. FIG. 3A is a waveform diagram when the offset voltage of the lighting device is low. FIG. 3B is a waveform diagram when the offset voltage of the lighting device is the medium level. FIG. 3C is a waveform diagram when the offset voltage of the lighting device is high. FIG. 4 is a waveform diagram of each part of the lighting device. FIG. 5 is a waveform diagram of each part of the lighting device according to the comparative example of the first embodiment of the present invention. FIG. 6 is a circuit diagram of a lighting device according to Embodiment 2 of the present invention. FIG. 7A is a perspective view of a lighting fixture according to Embodiment 3 of the present invention. FIG. 7B is a perspective view of a lighting fixture according to Modification 1 of Embodiment 3 of the present invention. FIG. 7C is a perspective view of a lighting fixture according to Modification 2 of Embodiment 3 of the present invention.

  Embodiment described below is only an example of the lighting device which concerns on this invention, and a lighting fixture provided with the same. The present invention is not limited to the following embodiments, and various modifications can be made in the following embodiments depending on the design or the like as long as the object of the present invention can be achieved.

(Embodiment 1)
(1.1) Configuration A lighting device 1 according to Embodiment 1 will be described with reference to FIGS.

  As shown in FIG. 1, the lighting device 1 of the present embodiment is a lighting device that lights a light source 3 that is a solid light source.

  The light source 3 includes a plurality of light emitting diodes connected in series. The light source 3 of the present embodiment is a plurality of light emitting diodes, but may be a single light emitting diode. The light source 3 may be a solid light source other than a light emitting diode, for example, an organic electroluminescence element.

  The lighting device 1 includes a lighting circuit 10, a control circuit 40, a first power supply circuit 50, a second power supply circuit 60, and a current / voltage conversion unit 13.

  The lighting circuit 10 converts an input voltage V <b> 1 from an AC power source 2 such as a commercial AC power source (for example, AC 100/200 V AC power source) into a DC output voltage and supplies it to the light source 3. The lighting circuit 10 of this embodiment includes a power factor correction circuit 20 and a step-down chopper circuit 30.

  The power factor correction circuit 20 has a circuit configuration of a boost chopper. The power factor correction circuit 20 includes a full-wave rectifier circuit 21, an inductor L1, a transistor Q1, a diode D1, and a smoothing capacitor C1.

  The full wave rectification circuit 21 performs full wave rectification on the input voltage V <b> 1 from the AC power supply 2. Between the output terminals of the full-wave rectifier circuit 21, an inductor L1 and a transistor Q1 are connected. The anode of the diode D1 is connected to the connection point between the inductor L1 and the transistor Q1. A smoothing capacitor C1 is connected between the cathode of the diode D1 and the low-voltage side output terminal of the full-wave rectifier circuit 21. The driver 22 controls the on / off of the transistor Q1, whereby the pulsating voltage input from the full-wave rectifier circuit 21 is converted into a constant DC voltage V2. In the present embodiment, the transistor Q1 is a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), but the transistor Q1 may be a bipolar transistor.

  The step-down chopper circuit 30 includes a transistor Q2, a diode D2, an inductor L2, and a capacitor C2.

  Between the output terminals of the power factor correction circuit 20, a transistor Q2 and a diode D2 are connected in series. An inductor L2 and a capacitor C2 are connected in series in parallel with the diode D2. A light source 3 is connected in parallel with the capacitor C2. In the present embodiment, the transistor Q2 is a MOSFET, but the transistor Q2 may be a bipolar transistor. The on / off state of the transistor Q2 is controlled by the control circuit 40.

  The first power supply circuit 50 includes a resistor R2, a diode D3, a smoothing capacitor C3, and a Zener diode ZD1. The inductor L1 of the power factor correction circuit 20 is provided with a secondary winding n1. A resistor R2, a diode D3, and a smoothing capacitor C3 are connected in series between both ends of the secondary winding n1 of the inductor L1. A Zener diode ZD1 is connected in parallel with the smoothing capacitor C3. In the first power supply circuit 50, the diode D3 rectifies the current generated in the secondary winding n1 of the inductor L1, and the smoothing capacitor C3 is charged by the current smoothed by the diode D3. Since the Zener diode ZD1 is connected in parallel with the smoothing capacitor C3, the voltage across the smoothing capacitor C3 (first DC voltage V11) is clamped to the Zener voltage of the Zener diode ZD1. That is, the first power supply circuit 50 generates the first DC voltage V11 that becomes the power supply voltage of the control circuit 40 from the input voltage V1 of the AC power supply 2.

  The second power supply circuit 60 includes resistors R5 and R6, a variable resistor VR1, and a Zener diode ZD1. A resistor R5 and a Zener diode ZD2 are connected in series between both ends of the smoothing capacitor C3 of the first power supply circuit 50. A variable resistor VR1 is connected in parallel with the Zener diode ZD2. One end of the resistor R6 is connected to the midpoint terminal of the variable resistor VR1. The other end of the resistor R6 is connected to the low-voltage side output end of the full-wave rectifier circuit 21 via the capacitor C4. The first DC voltage V11 is applied to the series circuit of the resistor R5 and the Zener diode ZD2, and a second DC voltage V12 obtained by stepping down the first DC voltage V11 is generated across the Zener diode ZD2. An offset voltage V13 obtained by dividing the second DC voltage V12 is generated at the midpoint terminal of the variable resistor VR1. That is, the second power supply circuit 60 generates an offset voltage V13 obtained by dividing the second DC voltage V12 obtained by stepping down the first DC voltage V11.

  The current-voltage conversion unit 13 is a resistor R1 connected in series to the current path through which the output current of the lighting circuit 10, that is, the current I2 flowing through the inductor L2, passes. The resistor R <b> 1 is connected between the light source 3 and the low-voltage side output end of the full-wave rectifier circuit 21. A voltage V3 having a voltage value corresponding to the current value of the output current (current I2) is generated between both ends of the resistor R1.

  The control circuit 40 includes components such as an SR flip-flop 41, comparators CP1 to CP3, an AND gate 42, and the like. The control circuit 40 may be an integrated circuit (IC) in which components such as the SR flip-flop 41, the comparators CP1 to CP3, and the AND gate 42 are integrated, or may be composed of discrete components.

  The plus terminal of the comparator CP1 is connected to a voltage source that generates the reference voltage Vth1. The inductor L2 is provided with a secondary winding n2, and the negative terminal of the comparator CP1 is connected to the secondary winding n2 of the inductor L2 via a resistor R3. When the current I2 flowing through the inductor L2 becomes zero, the output of the comparator CP1 changes from L level to H level, and the output of the SR flip-flop 41 changes to H level.

  The plus terminal of the comparator CP2 is connected to the connection point between the resistor R6 and the capacitor C4. A connection point between the resistor R6 and the capacitor C4 is connected to a connection point between the light source 3 and the resistor R1 via the resistor R4. Therefore, the voltage at the positive terminal of the comparator CP2 is a voltage V14 obtained by adding the offset voltage V13 to the voltage V3 across the resistor R1. The negative terminal of the comparator CP2 is connected to a voltage source that generates a threshold voltage Vth2. The output terminal of the comparator CP2 is connected to the reset terminal of the SR flip-flop 41. The comparator CP2 compares the voltage V14 with the threshold voltage Vth2. When the voltage V14 exceeds the threshold voltage Vth2, the output of the comparator CP2 changes from L level to H level, and the output of the SR flip-flop 41 changes to L level.

  The comparator CP3 compares the first DC voltage V11 of the first power supply circuit 50 with the lowest operating voltage Vth3 input from the voltage source. The minimum operating voltage Vth3 is a lower limit value of the power supply voltage at which the control circuit 40 can operate. If the first DC voltage V11 is equal to or higher than the minimum operating voltage Vth3, the output of the comparator CP3 becomes H level. The lower limit value may be a voltage that is higher than the lower limit voltage that guarantees the operation of the control circuit 40 by a predetermined voltage.

  To the AND gate 42, the output signal of the comparator CP3 and the output signal of the SR flip-flop 41 are input. The output terminal of the AND gate A1 is connected to the gate of the transistor Q2 through a buffer.

  Here, if the first DC voltage V11 is less than the minimum operating voltage Vth3, the output of the comparator CP3 becomes L level and the output of the AND gate A1 becomes L level. When the output of the AND gate A2 becomes L level, the transistor Q2 is turned off, so that the lighting circuit 10 stops the output and the light source 3 is turned off.

  If the first DC voltage V11 is equal to or higher than the minimum operating voltage Vth3, the output of the comparator CP3 becomes H level, and the AND gate 42 according to the high (H level) / low (L level) of the output of the SR flip-flop 41. Becomes an H level or an L level. When the current I2 flowing through the inductor L2 becomes zero, the output of the comparator CP1 becomes H level and the output of the SR flip-flop 41 becomes H level. As a result, the transistor Q2 is turned on, and a current flows through the light source 3. Thereafter, when the current I1 increases and the voltage V14 exceeds the threshold voltage Vth2, the output of the comparator CP2 becomes H level and the output of the SR flip-flop 41 becomes L level. As a result, the transistor Q2 is turned off and no current flows through the light source 3.

(1.2) Operation The operation of the lighting device 1 according to the first embodiment will be described with reference to FIGS.

  FIG. 2 is a waveform diagram of each part in a normal lighting state. 2 is a waveform diagram of the gate voltage of the transistor Q2, the current I2 flowing through the inductor L2 (output current of the lighting circuit 10), the offset voltage V13, the voltage V14, the voltage V15, and the load current I1 flowing through the light source 3 in order from the upper side of FIG. is there.

  In a state where the lighting circuit 10 is operating, a voltage V3 having a voltage value corresponding to the output current of the lighting circuit 10 (current I2 flowing through the inductor L2) is generated between both ends of the resistor R1.

  When the transistor Q2 is on, the current I2 flowing through the inductor L2 increases as the on-time of the transistor Q2 increases, and thus the voltage V3 increases. When the voltage V14 exceeds the threshold voltage Vth2 due to the increase in the voltage V3, the output of the comparator CP2 becomes H level. As a result, the output of the SR flip-flop 41 becomes L level, and the control circuit 40 turns off the transistor Q2.

  When the transistor Q2 is turned off, the current I2 flowing through the inductor L2 gradually decreases. When the control circuit 40 detects a zero crossing of the current I2, the control circuit 40 turns on the transistor Q2.

  As a result, the voltage across the capacitor C2 is controlled to a predetermined voltage value, and the load current I1 flowing through the light source 3 is controlled to a predetermined current value.

  Thus, when the voltage V14 obtained by adding the offset voltage V13 to the voltage V3 across the resistor R1 exceeds the threshold voltage Vth2, the control circuit 40 turns off the transistor Q2. That is, the on-time of the transistor Q2 is changed by the offset voltage V13, and the load current I1 flowing through the light source 3 is changed accordingly. Therefore, since the offset voltage changes by adjusting the resistance value of the variable resistor VR1 at the time of manufacturing the lighting device 1, the load current I1 flowing through the light source 3 can be adjusted.

  FIG. 3A is a waveform diagram of the voltage V14 and the load current I1 when the offset voltage V13 is at a low level (eg, zero volts). FIG. 3B is a waveform diagram of the voltage V14 and the load current I1 when the offset voltage V13 is at a medium level. FIG. 3C is a waveform diagram of the voltage V14 and the load current I1 when the offset voltage V13 is at a high level. Thus, as the offset voltage V13 increases, the on-time of the transistor Q2 is shortened, so that the load current I1 decreases. Further, as the offset voltage V13 decreases, the on-time of the transistor Q2 increases and the load current I1 increases.

  Here, the operation when the Zener diode ZD1 is not connected to the variable resistor VR1 of the second power supply circuit 60 (comparative example) will be described with reference to FIG. When the AC power supply 2 is not input to the lighting circuit 10 at time t1, the driver 22 stops operating and the transistor Q1 stops switching. As a result, no voltage is generated in the secondary winding of the inductor L1, so the first DC voltage V11 gradually decreases, and the offset voltage V13 also decreases accordingly.

  The smoothing capacitor C1 of the power factor correction circuit 20 generally has a large capacity in order to reduce ripples. Even when the input of the AC power supply 2 is stopped, the voltage V2 across the smoothing capacitor C1 does not drop immediately. . The power factor correction circuit 20 can supply power to the step-down chopper circuit 30 until the both-end voltage V <b> 2 falls below the forward voltage of the light source 3. Therefore, the load current I1 flows through the light source 3 until the first DC voltage V11 falls below the minimum operating voltage Vth3. During this period, the offset voltage V13 gradually decreases, and thus the load current I1 gradually increases. . As a result, an inrush current flows through the light source 3, stress is applied to the light source 3 and the like, and the light output instantaneously increases, so that flashing may occur.

  On the other hand, in the lighting device 1 of the present embodiment, the second power supply circuit 60 generates the offset voltage V13 from the second DC voltage V12 obtained by stepping down the first DC voltage V11, and the 2 DC voltage V2 Is set to a voltage lower than the minimum operating voltage Vth3. The operation of the lighting device 1 of the present embodiment will be described with reference to FIG.

  When AC power supply 2 is no longer input to lighting circuit 10 at time t1, transistor Q1 stops switching. As a result, no voltage is generated in the secondary winding of the inductor L1, and the first DC voltage V11 gradually decreases. However, while the first DC voltage V11 exceeds the minimum operating voltage Vth3, the second DC Since the voltage V12 does not change, the offset voltage V13 does not change. Therefore, the load current I1 flowing through the light source 3 is less likely to change when the light is turned off, and the possibility of an inrush current flowing through the light source 3 is reduced.

(1.3) Effect The lighting device 1 of the present embodiment includes the lighting circuit 10, the control circuit 40, the first power supply circuit 50, and the second power supply circuit 60. The lighting circuit 10 converts an input voltage from a power source (AC power source 2) into a DC output voltage and supplies the converted voltage to the light source 3. The control circuit 40 controls the output of the lighting circuit 10. The first power supply circuit 50 generates a first DC voltage V11 that becomes the power supply voltage of the control circuit 40 from the input voltage from the power supply. The current-voltage converter 13 (resistor R1) generates a voltage V3 having a voltage value corresponding to the current value of the output current (current I2) of the lighting circuit 10. The second power supply circuit 60 divides the second DC voltage V12 obtained by stepping down the first DC voltage V11 to generate the offset voltage V13. The second DC voltage V12 is set to a voltage lower than the lowest operating voltage Vth3 that is the lower limit value of the power supply voltage at which the control circuit 40 can operate. The control circuit 40 controls the output of the lighting circuit 10 based on a voltage V14 obtained by adding the offset voltage V13 to the voltage V3 generated by the current-voltage conversion unit 13. When the first DC voltage V11 generated by the first power supply circuit 50 falls below the minimum operating voltage Vth3, the control circuit 40 stops operating.

  As described above, the control circuit 40 controls the output of the lighting circuit 10 based on the voltage V14 obtained by adding the offset voltage V13 to the voltage V3 having a voltage value corresponding to the current value of the output current (current I2) of the lighting circuit 10. ing. The second DC voltage V12 is lower than the minimum operating voltage Vth3. Therefore, until the first DC voltage V11 falls below the minimum operating voltage Vth3, the offset voltage V13 becomes difficult to change, and the change of the voltage V14 can be suppressed. When the first DC voltage V11 falls below the minimum operating voltage Vth3, the control circuit 40 stops operating and the light source 3 is turned off. Therefore, the possibility that the operation of the lighting device 1 becomes unstable when the light is turned off can be reduced.

  Moreover, in the lighting device 1 of the present embodiment, the lighting circuit 10 is connected to the power source (AC power supply 2), and the DC that converts the output voltage of the power factor correction circuit 20 into a DC output voltage. / DC converter circuit (step-down chopper circuit 30). The lighting circuit 10 can be realized by a combination of the power factor correction circuit 20 and the DC / DC converter circuit. This configuration is not essential for the lighting device 1, and the circuit configuration of the lighting circuit 10A can be changed as appropriate.

(1.4) Modification of Embodiment 1 The first power supply circuit 50 generates the first DC voltage V11 from the output voltage of the full-wave rectifier circuit 21, but the first DC voltage V2 from the both-ends voltage V2 of the smoothing capacitor C1. The voltage V11 may be generated.

  The second power supply circuit 60 generates the offset voltage V13 by dividing the second DC voltage V12 with the variable resistor VR1, but the second power supply circuit 60 may form a voltage dividing circuit with a plurality of resistors connected in series. Good. That is, the offset voltage V13 may be generated by dividing the second DC voltage V12 with a plurality of resistors connected in series.

  In the lighting device 1 of the first embodiment, the discharge time constant of the second power supply circuit 60 that generates the second DC voltage V12 is set longer than the discharge time constant of the first power supply circuit 50 that generates the first DC voltage V11. May be. Thereby, when the light is extinguished, the fluctuation of the second DC voltage V12 is suppressed until the control circuit 40 stops its operation, so that the offset voltage V13 hardly changes. Therefore, the change in the voltage V14 can be suppressed, and the possibility that the operation of the lighting device 1 becomes unstable when the light is turned off can be reduced.

  If the discharge time constant of the second power supply circuit 60 that generates the second DC voltage V12 is made longer than the discharge time constant of the first power supply circuit 50 that generates the first DC voltage V11, the second power supply circuit 60 becomes a Zener. There is no need to provide a diode.

  In addition, the configuration (including modifications) described in the first embodiment is applied in appropriate combination with the configuration (including modifications) described in the second and third embodiments.

(Embodiment 2)
(2.1) Configuration A lighting device 1 according to Embodiment 2 will be described with reference to FIG.

  As illustrated in FIG. 6, the lighting device 1 according to the second embodiment includes a lighting circuit 10A, a control circuit 40A, a first power circuit 50A, a second power circuit 60, and a current-voltage conversion unit 13. . Note that the second power supply circuit 60 and the current-voltage conversion unit 13 have the same configuration as that of the first embodiment, and thus the description of the second power supply circuit 60 and the current-voltage conversion unit 13 is omitted.

  The lighting circuit 10 </ b> A includes a one-converter converter circuit 11 and a current control circuit 12.

  A converter circuit 11 of a single converter system includes a full-wave rectifier circuit 61, inductors L11 and L12, capacitors C11 to C13, a diode D11, a transistor Q11, and a driver 62, and a single-ended primary inductor converter (SEPIC). Circuit. The SEPIC circuit is a DC / DC converter circuit capable of stepping up and down. The SEPIC circuit is a one-converter type (one voltage conversion) converter circuit having a power factor correction circuit function and a DC / DC converter circuit function. When driver 62 controls on / off of transistor Q11, converter circuit 11 converts the pulsating voltage output from full-wave rectifier circuit 61 into a DC voltage having a predetermined voltage value. The detailed operation of the converter circuit 11 is not described here.

  The current control circuit 12 includes a transistor Q12 connected in series with the light source 3. Transistor Q12 is controlled by control circuit 40A. The transistor Q12 is, for example, a MOSFET, but may be a bipolar transistor.

  The first power supply circuit 50A includes an IPD (Intelligent Power Device) 51 and a smoothing capacitor C14. The IPD 51 generates the first DC voltage V11 by charging the smoothing capacitor C14 with the current input from the full-wave rectifier circuit 61.

  The control circuit 40A includes circuit components such as a comparator CP3 and an operational amplifier OP1. The control circuit 40A may be an IC in which circuit parts such as the comparator CP3 and the operational amplifier OP1 are integrated, or may be constituted by discrete parts.

  The comparator CP3 compares the first DC voltage V11 with the lowest operating voltage Vth3. When the first DC voltage V11 falls below the minimum operating voltage Vth3, the output of the comparator CP3 becomes H level, turning off the transistor Q12. Thereby, no current flows through the light source 3, and the light source 3 is turned off.

  The operational amplifier OP1 constitutes an error amplifier circuit 121, and a control function for controlling the transistor Q12 is realized by the error amplifier circuit 121. The operational amplifier OP1 amplifies the difference voltage between the voltage V14 obtained by adding the offset voltage V13 to the voltage V3 across the resistor R1 and the threshold voltage Vth2, and outputs the amplified voltage to the gate of the transistor Q12. That is, the error amplifier circuit 121 controls the transistor Q12 so that the output current (load current I1) has a current value corresponding to the difference between the voltage V14 and the threshold voltage Vth2. Here, the current control circuit 12 is configured by the transistor Q1 and the error amplifying circuit 121.

  Also in the lighting device 1 of the present embodiment, the second DC voltage V12 generated by the second power supply circuit 60 is set to a voltage lower than the minimum operating voltage Vth3. As a result, when the light is extinguished, the offset voltage V13 hardly changes until the first DC voltage V11 falls below the minimum operating voltage Vth3, so that the change in the voltage V14 is suppressed. When the first DC voltage V11 falls below the minimum operating voltage Vth3, the control circuit 40 stops operating and the light source 3 is turned off. Therefore, the possibility that the operation of the lighting device 1 becomes unstable when the light is turned off can be reduced.

(2.2) Effects In the lighting device 1 of the present embodiment, the lighting circuit 10A preferably includes a converter circuit 11 of a single converter system and a current control circuit 12. The converter circuit 11 converts an input voltage from the power supply (AC power supply 2) into a DC output voltage. The current control circuit 12 controls the current output from the converter circuit 11 to the light source 3.

  Since the converter circuit 11 of 1 converter system has the function of the power factor correction circuit and the function of the DC / DC converter, the lighting circuit 10A can be realized by one converter circuit 11. This configuration is not essential for the lighting device 1, and the circuit configuration of the lighting circuit 10A can be changed as appropriate.

(2.3) Modification of Embodiment 2 The first power supply circuit 50A generates the first DC voltage V11 from the output voltage of the full-wave rectifier circuit 61, but the first DC voltage V2 from the both-ends voltage V2 of the smoothing capacitor C11. The voltage V11 may be generated.

  In the lighting device 1 according to the second embodiment, the discharge time constant of the second power supply circuit 60 that generates the second DC voltage V12 may be longer than the discharge time constant of the capacitor C14 that generates the first DC voltage V11. Thereby, when the light is extinguished, the fluctuation of the second DC voltage V12 is suppressed until the control circuit 40 stops its operation, so that the offset voltage V13 hardly changes. Therefore, the change of the voltage V14 can be suppressed, and the possibility that the operation becomes unstable when the light is turned off can be reduced.

  If the discharge time constant of the second power supply circuit 60 that generates the second DC voltage V12 is made longer than the discharge time constant of the smoothing capacitor C14 that generates the first DC voltage V11, the second power supply circuit 60 causes the Zener diode to be connected. There is no need to prepare.

  Note that the configuration (including modifications) described in the second embodiment is applied in appropriate combination with the configuration (including modifications) described in the first and third embodiments.

(Embodiment 3)
Hereinafter, the lighting fixture according to the present embodiment will be described in detail.

  FIG. 7A is a perspective view of the lighting fixture 4A of the present embodiment.

  This lighting fixture 4 </ b> A includes the lighting device 1 described in any of the first and second embodiments, and a main body 70 </ b> A that houses the lighting device 1.

  The luminaire 4A is configured as a downlight that is embedded in the ceiling. The lighting fixture 4 </ b> A includes a main body 70 </ b> A that houses the light source 3 and the lighting device 1, and a reflection plate 71. The main body 70A includes a plurality of heat radiation fins 72 at the top. A power cable 73 is led out from the main body 70A. The power cable 73 connects between the lighting device 1 housed in the main body 70 </ b> A and the AC power source 2.

(Modification of Embodiment 3)
The lighting fixture provided with the lighting device 1 described in the first and second embodiments is not limited to the lighting fixture configured as a downlight, and may be a lighting fixture configured as a spotlight, or illumination configured in other forms. An instrument may be used.

  7B and 7C are lighting fixtures 4B and 4C configured as spotlights attached to the wiring duct 5. FIG.

  FIGS. 7B and 7C show a lighting fixture 4B (Modification 1) and a lighting fixture 4C (Modification 2) configured as spotlights attached to the wiring duct 5, respectively.

  As illustrated in FIG. 7B, the lighting fixture 4B of Modification 1 includes a main body 70B, a reflection plate 74, a connector portion 75, and an arm portion 76. The main body 70 </ b> B houses the light source 3 and the lighting device 1. The connector part 75 is attached to the wiring duct 5. The arm portion 76 couples the connector portion 75 and the main body 70B. The lighting device 1 housed in the main body 70 </ b> B and the connector portion 75 are connected via a power cable 77.

  Moreover, the lighting fixture 4C of the modified example 2 includes a main body 70C, a box 78, a connecting portion 80, and a power cable 81 as shown in FIG. 7C. The main body 70 </ b> C houses the light source 3. Box 78 accommodates lighting device 1. The connecting part 80 connects the main body 70 </ b> C and the box 78. The power cable 81 connects between the light source 3 housed in the main body 70 </ b> C and the lighting device 1 housed in the box 78. A connector portion 82 that is electrically and mechanically connected to the wiring duct 5 in a detachable state is provided on the upper surface of the box 78.

  The configuration described in the second embodiment (including modifications 1 and 2) can be applied in appropriate combination with the configuration described in the first and second embodiments (including modifications).

  As described above, the lighting fixtures 4A, 4B, and 4C according to the present embodiment include the lighting device 1 according to the first or second embodiment (including the modification) and the main bodies 70A, 70B, and 70C that hold the lighting device 1. I have. Since the lighting fixtures 4A, 4B, and 4C include the lighting device 1 described in the first or second embodiment, it is possible to reduce the possibility that the operation becomes unstable when the lights are turned off.

1 lighting device 2 AC power supply (power supply)
3 light source 4A-4C lighting fixture 10, 10A lighting circuit 11 converter circuit 12 current control circuit 13 current voltage conversion unit 20 power factor improvement circuit 30 DC / DC converter circuit 40, 121 control circuit 50, 50A first power supply circuit 60 second Power supply circuit 70A-70C body R1 resistor (current-voltage converter)
V11 1st DC voltage V12 2nd DC voltage V13 Offset voltage Vth3 Minimum operating voltage

Claims (4)

A lighting circuit that converts the input voltage from the power supply to a DC output voltage and supplies it to the light source;
A control circuit for controlling the output of the lighting circuit;
A first power supply circuit that generates a first DC voltage to be a power supply voltage of the control circuit from an input voltage from the power supply;
A current-voltage converter that generates a voltage having a voltage value corresponding to the current value of the output current of the lighting circuit;
A second power supply circuit for generating an offset voltage by dividing the second DC voltage obtained by stepping down the first DC voltage;
The second DC voltage is set to a voltage lower than a minimum operating voltage that is a lower limit value of a power supply voltage at which the control circuit can operate,
The control circuit controls the output of the lighting circuit based on a voltage obtained by adding the offset voltage to the voltage generated by the current-voltage conversion unit,
When the first DC voltage generated by the first power supply circuit falls below the minimum operating voltage, the control circuit stops operating.
A lighting device characterized by that. The lighting circuit includes a power factor correction circuit connected to the power source, and a DC / DC converter circuit that converts an output voltage of the power factor correction circuit into a DC output voltage.
The lighting device according to claim 1. The lighting circuit includes a converter circuit that converts an input voltage from the power source into a DC output voltage, and a current control circuit that controls a current output from the converter circuit to the light source.
The lighting device according to claim 1. The lighting device according to any one of claims 1 to 3,
A lighting fixture comprising: a main body for holding the lighting device.

Images