JP7444009B2 - Lighting devices and luminaires - Google Patents

Description

The present disclosure relates to lighting devices and lighting fixtures.

Patent Document 1 discloses a power supply device that generates a DC voltage by boosting the output of an AC power supply AC rectified by a diode bridge using a boost chopper circuit. A current limiting element that prevents inrush current is inserted into the supply path that supplies the output of the diode bridge to the boost chopper circuit. Further, the power supply device includes a switching element that short-circuits the current limiting element after suppressing the inrush current. As the inductor of the boost chopper circuit, one having a secondary winding wound with the same polarity as the primary winding is used. The switching element is turned on using the voltage induced in the secondary winding.

Japanese Unexamined Patent Publication No. 7-147770

Since commercial power is alternating current, there is no polarity. On the other hand, DC power supplies have polarity. For this reason, there is a risk of incorrect wiring when wiring the DC power source and the lighting device.

The present disclosure has been made to solve the above-mentioned problems, and aims to provide a lighting device and a lighting fixture that can protect against incorrect wiring.

A lighting device according to the present disclosure includes: a pair of current supply lines that receive power from a DC power supply; a lighting circuit that receives power from the DC power supply via the pair of current supply lines and lights up a light source; a series circuit having a current limiting element and a first diode connected in series and provided on the high potential side of the pair of current supply lines; a bypass circuit connected in parallel with the series circuit; and the lighting. a voltage adjustment circuit that brings the bypass circuit into a conductive state by a voltage generated by the circuit, the first diode has an anode connected to the DC power supply side, a cathode connected to the lighting circuit side, and the first diode has an anode connected to the lighting circuit side , The circuit has a coil connected to the high potential side of the pair of current supply lines .

In the lighting device according to the present disclosure, the first diode can protect against incorrect wiring.

1 is a circuit block diagram of a lighting fixture according to Embodiment 1. FIG. FIG. 3 is a diagram illustrating a voltage waveform of the lighting device according to the first embodiment. FIG. 3 is a circuit block diagram of a lighting fixture according to Embodiment 2. FIG. 3 is a circuit block diagram of a lighting fixture according to Embodiment 3. FIG.

A lighting device and a lighting fixture according to each embodiment will be described with reference to the drawings. Identical or corresponding components may be given the same reference numerals and repeated descriptions may be omitted. In addition, in the following, the term "connection" includes electrical connection.

Embodiment 1.
FIG. 1 is a circuit block diagram of a lighting fixture 100 according to the first embodiment. The lighting fixture 100 includes a lighting device 10 and a light source section 50. Furthermore, the lighting fixture 100 includes a connection part CN1 that connects a DC power supply DC supplied from the outside, and a connection part CN2 that connects to the light source part 50.

The light source section 50 is composed of a plurality of LEDs 51. The light source section 50 may be composed of light emitting elements other than the LED 51. Moreover, the number of LEDs 51 included in the light source section 50 may be one or more. The plurality of LEDs 51 are connected in series, in parallel, or in series and parallel.

The lighting device 10 includes a lighting circuit 30 and a lighting control IC 40 that controls the lighting circuit 30. The lighting circuit 30 is, for example, a switching circuit. Specifically, the lighting circuit 30 is a boost chopper circuit. The boost chopper circuit converts the DC power supply DC into voltage. A light source unit 50 that is turned on at a voltage higher than the DC power supply DC is connected to the output of the boost chopper circuit.

The lighting device 10 also includes a pair of current supply lines 11 and 12 that receive power from a direct current power source DC. The lighting circuit 30 receives power from a direct current power supply DC via a pair of current supply lines 11 and 12, and lights the light source section 50.

The boost chopper circuit includes a coil L1, a switching element Q2, and a diode D3. The switching element Q2 is, for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). The lighting circuit 30 lights the light source section 50 by turning on and off the switching element Q2.

The N1 winding side of the coil L1 is connected to the current supply line 11. The N2 winding side of the coil L1 is connected to the drain of the switching element Q2 and the anode of the diode D3. The cathode of the diode D3 is connected to the positive electrode of the capacitor C4 and the high potential side of the light source section 50. The low potential side of the light source section 50 is connected to one end of the resistor R1 and the negative electrode of the capacitor C4. The other end of resistor R1 is connected to the source of switching element Q2 and current supply line 12. Capacitor C4 is connected in parallel with the output of lighting circuit 30. The lighting device 10 can rectify the high frequency voltage output from the diode D3 using the capacitor C4 and supply it to the light source section 50.

The gate of the switching element Q2 is connected to the P1 terminal of the lighting control IC40. The lighting control IC 40 drives the switching element Q2. One end of the resistor R1 is connected to the P2 terminal of the lighting control IC 40. The lighting control IC 40 detects the voltage of the resistor R1.

A current that flows through the capacitor C4 and the light source section 50 flows through the resistor R1. The average value of the current flowing through the light source section 50 can be detected by the resistor R1. The lighting control IC 40 converts the current flowing through the resistor R1 into a voltage and detects it at the P2 terminal. The lighting control IC 40 switches the switching element Q2 so that the voltage generated across the resistor R1 becomes a predetermined voltage. This enables constant current control so that the average current flowing through the light source section 50 is constant.

Note that the connection position to the resistor R1 may be between the low potential side of the light source section 50 and the negative electrode of the capacitor C4. At this position, a pure current flowing through the light source section 50 can be detected.

The current supply line 11, which is the high potential side of the pair of current supply lines 11 and 12, is provided with a series circuit 21 having a current limiting element R2 and a diode D1 connected in series. The diode D1 has an anode connected to the DC power supply DC side and a cathode connected to the lighting circuit 30 side.

A bypass circuit is connected in parallel with the series circuit 21. The bypass circuit includes a thyristor Q1. Thyristor Q1 has a first terminal electrically connected to one end of series circuit 21 and a second terminal electrically connected to the other end of series circuit 21. The first terminal is an anode and is connected to the positive electrode of a direct current power source DC. The second terminal is a cathode and is connected to the N1 winding side of the coil L1. Moreover, the thyristor Q1 has a control terminal for switching between the first terminal and the second terminal into a conductive state or a cutoff state. The control terminal is a gate.

The lighting device 10 includes a voltage adjustment circuit 22 that brings the bypass circuit into conduction using the voltage generated by the lighting circuit 30. The voltage adjustment circuit 22 supplies a voltage to the control terminal of the thyristor Q1 to turn on the bypass circuit.

Voltage adjustment circuit 22 is connected between thyristor Q1 and coil L1. The voltage adjustment circuit 22 includes a diode D2 having an anode electrically connected to the coil L1 and supplied with current from the coil L1. Coil L1 is divided into N1 winding and N2 winding. The anode of diode D2 is connected to the junction of the N1 and N2 windings. A cathode of diode D2 is connected to one end of capacitor C2 and one end of resistor R3.

The other end of the capacitor C2 is connected to the connection point between the coil L1 and the series circuit 21. The voltage across capacitor C2 is equal to the voltage developed in the series circuit formed by diode D2 and N1 winding of coil L1. The other end of resistor R3 is connected to one end of resistor R4, one end of capacitor C3, and the gate of thyristor Q1. Capacitor C3 and resistor R4 are connected in parallel. Capacitor C3 and resistor R4 are connected between the gate and cathode of thyristor Q1.

Capacitor C3 may have a smaller capacitance than capacitor C2. Capacitor C3 is connected for voltage stabilization in order to prevent malfunction of thyristor Q1.

The cathode of thyristor Q1 and the N1 winding of coil L1 are connected to one end of capacitor C1. The other end of the capacitor C1 is connected to the negative electrode of the DC power supply DC. The capacitor C1 is connected between the lighting circuit 30 and the series circuit 21 and between the pair of current supply lines 11 and 12. The capacitor C1 stably smoothes the voltage supplied from the DC power supply DC, and supplies a power supply voltage for operating the boost chopper circuit.

Next, the operation of the lighting fixture 100 will be described. First, power is turned on to the lighting fixture 100 from the direct current power supply DC using a switch or the like (not shown). At this time, thyristor Q1 is off, and current flows through the first path and the second path. The first path is a path passing through the diode D1, the current limiting element R2, and the capacitor C1. The second path is a path passing through the diode D1, current limiting element R2, coil L1, diode D3, and capacitor C4. The sum of the currents in the first path and the second path is the rush current.

At this time, the inrush current can be suppressed by the impedance of the current limiting element R2, and the inrush current value can be controlled. Therefore, it is possible to prevent a load that is more than expected from being applied to the components that constitute the lighting fixture 100. Further, the occurrence of undershoot in the output voltage of the lighting device 10 can be suppressed.

Note that if the boost chopper circuit does not operate, a voltage higher than that of the direct current power supply DC will not be supplied to the light source section 50. Therefore, no current flows through the light source section 50, and the light source section 50 cannot be lit.

Next, the lighting control IC 40 is activated and the boost chopper circuit operates. FIG. 2 is a diagram illustrating a voltage waveform of the lighting device 10 according to the first embodiment. The boost chopper circuit is stopped until time T1. At this time, no voltage is applied to the gate of the switching element Q2, and the switching element Q2 is turned off. Further, no potential difference is generated in the coil L1.

During the period from time T1 to T2, switching element Q2 is turned on by applying a voltage to its gate. Therefore, the drain of the switching element Q2 becomes the ground potential. As a result, -VDC is applied to the coil L1. VDC is the voltage of a direct current power supply DC. At this time, the potential at the connection point between the N1 winding and the N2 winding is lower than the potential at the cathode of the diode D2. Therefore, no current flows through the diode D2.

During the period from time T2 to T3, switching element Q2 is turned off because no voltage is applied to its gate. Therefore, a voltage V1 of the light source section 50, which is higher than the DC power supply DC, is generated at the drain of the switching element Q2. As a result, V1-VDC is applied to the coil L1. Note that the voltage V1 is sufficiently higher than the forward voltage VF of the diode D3. Therefore, the forward voltage VF of the diode D3 is ignored.

At this time, the potential at the connection point between the N1 winding and the N2 winding is higher than the potential at the cathode of the diode D2. Therefore, a voltage is applied to capacitor C2 via diode D2. The voltage applied to the capacitor C2 is a voltage obtained by dividing V1-VDC by the turn ratio of the N1 winding and the N2 winding. Here, the forward voltage VF of the diode D2 is ignored.

A voltage obtained by dividing the voltage of capacitor C2 by resistors R3 and R4 is applied between the gate and cathode of capacitor C3, that is, thyristor Q1. When this voltage exceeds the on-voltage Vth of thyristor Q1, thyristor Q1 is turned on. In this manner, the voltage adjustment circuit 22 includes a capacitor C3 that receives current from the coil L1 and generates a voltage for bringing the bypass circuit into conduction.

During the period from time T3 to time T4, switching element Q2 is turned on by applying voltage to its gate again. At this time, the potential at the connection point between the N1 winding and the N2 winding is lower than the potential at the cathode of the diode D2. However, the charge on capacitor C2 is blocked by diode D2 and discharged only into resistors R3 and R4. The voltage on capacitor C2 drops by ΔV. Similarly, the voltage of capacitor C3 also decreases, but is maintained at a value greater than the on-voltage Vth of thyristor Q1. Further, a current higher than the holding current flows through the thyristor Q1. Therefore, the conduction state of the thyristor Q1 can be continued.

In this way, while the switching element Q2 is in the on state, the supply of current from the coil L1 to the voltage adjustment circuit 22 is cut off. On the other hand, even while the switching element Q2 is in the on state, the voltage adjustment circuit 22 maintains the bypass circuit in the conductive state.

At time T4, the voltage is no longer applied to the gate of the switching element Q2 again, and the switching element Q2 is turned off. As a result, a voltage is applied to the capacitor C2 via the diode D2 similarly to time T2. After that, the operation is repeated.

In the absence of thyristor Q1, the input current from DC power supply DC is supplied to the boost chopper circuit via diode D1 and current limiting element R2 even during steady operation. Therefore, a loss occurs due to the voltage drop of the diode D1 and the resistance value of the current limiting element R2. The current flowing from the DC power source DC increases as the power consumption of the light source section 50 increases. At this time, the loss also increases.

In contrast, the voltage adjustment circuit 22 of the present embodiment brings the bypass circuit into a conductive state by the voltage generated in the coil L1 as the switching element Q2 turns on and off. Specifically, the voltage adjustment circuit 22 generates a voltage for bringing the bypass circuit into conduction from the voltage generated in the coil L1 when the switching element Q2 is in the off state. Thereby, after the inrush current is suppressed by the current limiting element R2, the thyristor Q1 can be turned on by the lighting operation of the boost chopper circuit. When the thyristor Q1 is turned on, the input current from the DC power supply DC is supplied to the boost chopper circuit via the thyristor Q1. Therefore, the loss caused by the series circuit 21 can be reduced.

Here, a voltage drop also occurs between the anode and cathode of the thyristor Q1, but the voltage drop of the thyristor Q1 is smaller than the sum of the voltage drops due to the diode D1 and the current limiting element R2. The voltage drop across the diode D1 is about 0.6V. Furthermore, it is desirable that the current limiting element R2 has a resistance of about 100Ω in order to suppress inrush current. For example, when the DC power supply DC is 48V, the rush current is limited by 100Ω of the current limiting element R2 and becomes 0.48A.

Further, if the power consumption of the lighting fixture 100 is 24W, the input current from the DC power supply DC will be about 0.5A. At this time, the voltage drop across the current limiting element R2 is approximately 50V. On the other hand, the voltage drop between the anode and cathode of thyristor Q1 is about 1.2V. Therefore, when the input current flows through the thyristor Q1, the circuit loss is smaller than when the input current flows through the diode D1 and the current limiting element R2. Note that when the rush current is 0.48A, it is smaller than the steady state input current of 0.5A. Therefore, it can be said that the rush current can be sufficiently suppressed.

Next, the operation when the DC power supply DC is reversely connected to the connection part CN1 of the lighting fixture 100 will be described. When the lighting fixture 100 is powered on with the DC power source DC connected with reverse polarity, a voltage is applied from the capacitor C1, the parasitic diode between the source and drain of the switching element Q2, and the like. However, thyristor Q1 and diode D1 block current from flowing. Therefore, it is possible to suppress failure or malfunction due to application of reverse voltage to the circuit. Therefore, protection against incorrect wiring can be achieved. Note that if the diode D1 is not present, current will continue to flow through the current limiting element R2, and there is a risk that the lighting fixture 100 will malfunction.

Even if the diode D1 is connected in series with the anode or cathode of the thyristor Q1, it can suppress failure due to application of reverse voltage. However, even in a normally wired state, the input current from the DC power supply DC flows through the diode D1, resulting in circuit loss due to a voltage drop across the diode D1. Therefore, it can be seen that the circuit configuration of this embodiment is superior from the viewpoint of reducing energy consumption. In this way, in this embodiment, it is possible to protect against incorrect wiring while suppressing inrush current, and furthermore, it is possible to suppress energy consumption.

Further, in this embodiment, the series circuit 21 and the thyristor Q1 are provided on the high potential side of the pair of current supply lines 11 and 12. With this configuration, the circuit ground of the lighting device 10 can be stabilized compared to a configuration in which the series circuit 21 and the thyristor Q1 are provided on the low potential side of the pair of current supply lines 11 and 12. Therefore, malfunction of the lighting circuit 30 can be suppressed. Further, the voltage adjustment circuit 22 is supplied with driving power from the coil L1. In such a system, since the thyristor Q1 is provided on the high potential side of the pair of current supply lines 11 and 12, driving power can be easily supplied with fewer parts.

As a modification of this embodiment, the bypass circuit may have a different configuration as long as it is switched to the conductive state by the voltage generated by the lighting circuit 30. For example, the bypass circuit is not limited to the thyristor Q1, but may include other types of switching elements such as a bipolar transistor and a relay switch.

Further, the current limiting element R2 may be connected not only to the cathode side of the diode D1 but also to the anode side. Further, the voltage adjustment circuit 22 may have a different configuration as long as the bypass circuit can be set to a conductive state by the voltage generated by the lighting circuit 30.

This embodiment can be applied to, for example, a DC power supply system using a solar cell or a storage battery. Further, this embodiment may be applied to a DC power supply system using AC/DC conversion. Further, a plurality of lighting fixtures 100 may be installed in one DC power supply DC. At this time, protection against transient currents especially when the power is turned on is important. Further, as described above, by providing the series circuit 21 and the thyristor Q1 on the high potential side of the pair of current supply lines 11 and 12, the circuit ground of the lighting device 10 can be stabilized. Therefore, the plurality of lighting devices 10 can operate at the same reference potential using the negative electrode of one DC power source DC as the circuit ground. Therefore, when issuing a dimming command to a plurality of lighting devices 10 using one dimming controller provided externally, the lighting devices 10 can be stably operated. Further, there is no need to provide a plurality of dimming controllers and insulating the dimming controllers.

These modifications can be applied as appropriate to the lighting devices and lighting fixtures according to the following embodiments. Note that the lighting device and lighting fixture according to the following embodiments have many features in common with Embodiment 1, so the description will focus on the differences from Embodiment 1.

Embodiment 2.
FIG. 3 is a circuit block diagram of lighting fixture 200 according to the second embodiment. The lighting fixture 200 includes a lighting device 210. The lighting device 210 includes a lighting circuit 230 and a lighting control IC 240 that controls the lighting circuit 230. The lighting circuit 230 is a flyback circuit. The lighting fixture 200 of this embodiment can operate even if the voltage of the light source section 50 is higher or lower than the DC power supply DC. In other words, the lighting circuit 230 is a step-up/down circuit.

The cathode of thyristor Q1 is connected to the N1 winding side of coil L2. The N2 winding side of the coil L2 is connected to the drain of the switching element Q3. The switching element Q3 is, for example, a MOSFET. The source of switching element Q3 is connected to the negative electrode of capacitor C1. The P3 terminal of the lighting control IC 240 is connected to the gate of the switching element Q3. The lighting control IC 240 drives the switching element Q3. Further, the P4 terminal of the lighting control IC 240 detects the voltage of the resistor R1.

One end of the N3 winding, which is the secondary winding of the coil L2, is connected to the anode of the diode D4. The other end of the N3 winding is connected to the current supply line 12. The cathode of the diode D4 is connected to the positive electrode of the capacitor C4 and the high potential side of the light source section 50. The lighting device 210 can rectify the high frequency voltage output from the diode D4 using the capacitor C4 and supply it to the light source section 50.

The lighting control IC 240 converts the current flowing through the resistor R1 into a voltage and detects it at the P4 terminal. The lighting control IC 240 switches the switching element Q3 so that the voltage generated across the resistor R1 becomes a predetermined voltage. This enables constant current control so that the average current flowing through the light source section 50 is constant.

The primary winding of coil L2 is divided into N1 winding and N2 winding. Diode D2 of voltage adjustment circuit 22 is connected to the connection point between winding N1 and winding N2. Thereby, as in the first embodiment, the driving power for the thyristor Q1 can be obtained from the voltage generated in the coil L2 as the switching element Q3 turns on and off.

When power is turned on from the DC power source DC, the thyristor Q1 is off, so a rush current flows through the path of the diode D1, the current limiting element R2, and the capacitor C1.

When the lighting control IC 240 is activated, the flyback circuit operates. Thereafter, when the switching element Q3 is turned off, the voltage V1 applied to the light source section 50 is divided into the primary winding of the coil L2 by the turn ratio of the secondary winding and the primary winding of the coil L2. voltage is generated. Note that the forward voltage VF of the diode D4 is ignored. Furthermore, a voltage is generated at the connection point between the N1 winding and the N2 winding, which is obtained by dividing the voltage generated in the primary winding of the coil L2 by the turn ratio of the N1 winding and the N2 winding. Therefore, also in this embodiment, the drive voltage for thyristor Q1 can be obtained via diode D2.

Embodiment 3.
FIG. 4 is a circuit block diagram of lighting fixture 300 according to the third embodiment. The lighting fixture 300 includes a lighting device 310. The lighting device 310 includes a lighting circuit 330 and a lighting control IC 340 that controls the lighting circuit 330. The lighting circuit 330 is a step-down chopper circuit. The lighting fixture 300 of this embodiment can operate when the voltage of the light source section 50 is lower than the DC power supply DC.

The cathode of thyristor Q1 is connected to the drain of switching element Q4. The switching element Q4 is, for example, a MOSFET. The source of the switching element Q4 is connected to the cathode of the diode D5 and one end of the N1 winding of the coil L3. The other end of the N1 winding of the coil L3 is connected to the positive electrode of the capacitor C4 and the high potential side of the light source section 50. The anode of diode D5 is connected to the other end of resistor R1 and current supply line 12. The lighting device 310 can rectify the high frequency voltage obtained from the N1 winding side of the coil L3 using the capacitor C4 and supply it to the light source section 50.

The P5 terminal of the lighting control IC 340 is connected to the gate of the switching element Q4. The lighting control IC 340 drives the switching element Q4. Further, the P6 terminal of the lighting control IC 340 is connected to one end of the resistor R1, and detects the voltage of the resistor R1. The lighting control IC 340 converts the current flowing through the resistor R1 into a voltage and detects it at the P6 terminal. The lighting control IC 340 switches the switching element Q4 so that the voltage generated across the resistor R1 becomes a predetermined voltage. This enables constant current control so that the average current flowing through the light source section 50 is constant.

One end of the N2 winding, which is the secondary winding of the coil L3, is connected to the anode of the diode D2. As a result, similarly to the first embodiment, the driving power for the thyristor Q1 can be obtained from the voltage generated in the coil L3 as the switching element Q4 turns on and off. The other end of the N2 winding of coil L3 is connected to the cathode of thyristor Q1.

When power is turned on from the DC power source DC, the thyristor Q1 is off, so a rush current flows through the path of the diode D1, the current limiting element R2, and the capacitor C1.

When the lighting control IC 340 is activated, the step-down chopper circuit operates. Thereafter, when the switching element Q4 is turned off, the N2 winding of the coil L3 receives a voltage obtained by dividing the voltage V1 applied to the light source section 50 by the turn ratio of the N2 winding and the N1 winding of the coil L3. Occur. Here, the forward voltage VF of the diode D5 is ignored. Therefore, the driving voltage for the thyristor Q1 can be obtained via the diode D2.

Note that the technical features described in each embodiment may be used in combination as appropriate.

10 lighting device, 11, 12 current supply line, 21 series circuit, 22 voltage adjustment circuit, 30 lighting circuit, 50 light source section, 51 LED, 100, 200 lighting fixture, 210 lighting device, 230 lighting circuit, 300 lighting fixture, 310 Lighting device, 330 Lighting circuit, AC AC power supply, C1, C2, C3, C4 Capacitor, CN1, CN2 Connection part, D1, D2, D3, D4, D5 Diode, DC DC power supply, 40, 240, 340 Lighting control IC, L1, L2, L3 coil, Q1 thyristor, Q2, Q3, Q4 switching element, R1 resistor, R2 current limiting element, R3, R4 resistor

Claims (14)

a pair of current supply lines receiving power from a DC power supply;
a lighting circuit that receives power from the DC power source via the pair of current supply lines and lights up the light source;
a series circuit including a current limiting element and a first diode connected in series and provided on the high potential side of the pair of current supply lines;
a bypass circuit connected in parallel with the series circuit;
a voltage adjustment circuit that brings the bypass circuit into conduction using a voltage generated by the lighting circuit;
Equipped with
The first diode has an anode connected to the DC power supply side and a cathode connected to the lighting circuit side ,
A lighting device characterized in that the lighting circuit includes a coil connected to a high potential side of the pair of current supply lines . The lighting device according to claim 1, further comprising a first capacitor connected between the pair of current supply lines between the lighting circuit and the series circuit. The lighting device according to claim 1 or 2, further comprising a second capacitor connected in parallel with the output of the lighting circuit. The lighting circuit includes a first switching element and the coil, and lights a light source by turning on and off the first switching element,
The lighting according to any one of claims 1 to 3, wherein the voltage adjustment circuit brings the bypass circuit into the conductive state by a voltage generated in the coil as the first switching element turns on and off. Device. 5. The voltage adjustment circuit generates a voltage for bringing the bypass circuit into the conducting state from a voltage generated in the coil when the first switching element is in the off state. lighting device. 6. The lighting device according to claim 4, wherein the voltage adjustment circuit includes a second diode having an anode electrically connected to the coil and supplied with current from the coil. 7. The voltage adjustment circuit includes a third capacitor that receives current from the coil and generates a voltage for bringing the bypass circuit into the conducting state. The lighting device described in . 4. While the first switching element is in the on state, supply of current from the coil to the voltage regulation circuit is cut off, and the voltage regulation circuit maintains the bypass circuit in the conductive state. 7. The lighting device according to any one of 7. The bypass circuit includes a first terminal electrically connected to one end of the series circuit, a second terminal electrically connected to the other end of the series circuit, and the first terminal and the second terminal. a second switching element having a control terminal for switching between a conduction state or a cutoff state;
The lighting device according to any one of claims 1 to 8, wherein the voltage adjustment circuit supplies a voltage to the control terminal to bring the bypass circuit into the conductive state. The lighting device according to claim 9, wherein the second switching element is a thyristor. 11. The lighting device according to claim 1, wherein the lighting circuit is a step-up chopper circuit. 11. The lighting device according to claim 1, wherein the lighting circuit is a flyback circuit. 11. The lighting device according to claim 1, wherein the lighting circuit is a step-down chopper circuit. The lighting device according to any one of claims 1 to 13,
the light source;
A lighting fixture comprising:

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