Lighting devices and lighting fixtures

Abstract

The aim is to achieve both protection against lightning surges and protection in the event of a failure in the lighting circuit. [Solution] The lighting device 1 comprises a lighting circuit 17, a surge absorption circuit (first surge absorption circuit 11), a first protection circuit 13, and a second protection circuit 14. The lighting circuit 17 is connected to an external power supply 3 via a first power line L1 and a second power line L2, generates a second power based on the first power supplied from the external power supply 3, and supplies the generated second power to the light source 2. The surge absorption circuit is not connected to the second power line L2, but is connected between the external power supply 3 and the earth 4 via the first power line L1. The first protection circuit 13 is connected to the external power supply 3 side of the surge absorption circuit. The second protection circuit 14 is connected to the lighting circuit 17 side of the surge absorption circuit.

Description

Technical Field

[0001] The present disclosure relates to a lighting device and a lighting fixture. More specifically, the present disclosure relates to a lighting device including a surge absorption circuit and a plurality of protection circuits, and a lighting fixture including the lighting device.

Background Art

[0002] Patent Document 1 describes a lighting device including a lighting control circuit and an input circuit. The input circuit supplies DC power obtained by converting AC power supplied from an AC power source through two AC lines to the lighting control circuit using a rectifier circuit. The input circuit also includes a surge protection element circuit, a first fuse, and a second fuse.

[0003] The surge protection element circuit switches from a non-conductive state to a conductive state at a predetermined operating voltage applied to the two AC lines. The first fuse is arranged on the two AC lines on the input side of the surge protection element circuit and melts due to a short-circuit current in case of a failure of the surge protection element circuit. The second fuse is arranged on at least one of the two AC lines on the output side of the surge protection element circuit and melts due to an increase in current or a short-circuit current in case of a failure of the lighting control circuit.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a lighting device as described in Patent Document 1, it is necessary to achieve both protection against lightning surges and protection in case of a failure of an internal circuit (lighting control circuit).

[0006] The purpose of this disclosure is to provide a lighting device and lighting fixture that can achieve both protection against lightning surges and protection in the event of internal circuit failure. [Means for solving the problem]

[0007] A lighting device according to one aspect of the present disclosure comprises a lighting circuit, a surge absorption circuit, a first protection circuit, and a second protection circuit. The lighting circuit is connected to an external power supply via a first power line and a second power line, generates a second power based on a first power supplied from the external power supply, and supplies the generated second power to a light source. The surge absorption circuit is not connected to the second power line, but is connected between the external power supply and ground via the first power line. The first protection circuit is connected to the external power supply side of the surge absorption circuit. The second protection circuit is connected to the lighting circuit side of the surge absorption circuit.

[0008] A lighting device according to another aspect of the present disclosure comprises a lighting circuit, a surge absorption circuit, a first protection circuit, and a second protection circuit. The lighting circuit is connected to an external power supply via a first power line and a second power line, generates a second power based on a first power supplied from the external power supply, and supplies the generated second power to a light source. The surge absorption circuit is connected between the external power supply and ground via the first power line. The first protection circuit is connected to the external power supply side of the surge absorption circuit. The second protection circuit is connected to the lighting circuit side of the surge absorption circuit. The first power line includes a third power line connecting the external power supply and the surge absorption circuit, and a fourth power line connecting the external power supply and the lighting circuit. The first protection circuit is connected between the external power supply and the surge absorption circuit in the third power line. The second protection circuit is connected between the external power supply and the lighting circuit in the fourth power line.

[0009] A lighting device according to another aspect of the present disclosure comprises a lighting circuit, a first surge absorption circuit, a second surge absorption circuit, a first protection circuit, and a second protection circuit. The lighting circuit is connected to an external power supply via a first power line and a second power line, generates a second power based on a first power supplied from the external power supply, and supplies the generated second power to a light source. The first surge absorption circuit is connected between the external power supply and ground via the first power line. The second surge absorption circuit is connected between the first power line and the second power line. The first protection circuit is connected to the external power supply side of the surge absorption circuit. The second protection circuit is connected to the lighting circuit side of the surge absorption circuit. The first power line is a single power line. The first protection circuit is connected between the external power supply and the first surge absorption circuit on the first power line. The second protection circuit is connected between the second surge absorption circuit and the lighting circuit on the first power line.

[0010] A lighting fixture according to one aspect of this disclosure comprises the lighting device and the light source. [Effects of the Invention]

[0011] According to one aspect of this disclosure, a lighting device and lighting fixture can be provided that provide both protection against lightning surges and protection in the event of internal circuit failure. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic diagram of the lighting device and lighting fixture according to Embodiment 1. [Figure 2] Figure 2 is a schematic diagram of a lighting device and lighting fixture according to a modified example 1 of Embodiment 1. [Figure 3] Figure 3 is a schematic diagram of a lighting device and lighting fixture according to a modified example 2 of Embodiment 1. [Figure 4] Figure 4 is a schematic diagram of the lighting device and lighting fixture according to modification 3 of Embodiment 1. [Figure 5]FIG. 5 is a schematic configuration diagram of a lighting device and a lighting fixture according to Modification Example 4 of Embodiment 1. [Figure 6] FIG. 6 is a schematic configuration diagram of a lighting device and a lighting fixture according to Modification Example 5 of Embodiment 1. [Figure 7] FIG. 7 is a schematic configuration diagram of a lighting device and a lighting fixture according to Embodiment 2. [Figure 8] FIG. 8 is a schematic configuration diagram of a lighting device and a lighting fixture according to Modification Example 1 of Embodiment 2. [Figure 9] FIG. 9 is a schematic configuration diagram of a lighting device and a lighting fixture according to Modification Example 2 of Embodiment 2. [Figure 10] FIG. 10 is a schematic configuration diagram of a lighting device and a lighting fixture according to Modification Example 3 of Embodiment 2. [Figure 11] FIG. 11 is a schematic configuration diagram of a lighting device and a lighting fixture according to Modification Example 4 of Embodiment 2. [Figure 12] FIG. 12 is a schematic configuration diagram of a lighting device and a lighting fixture according to Modification Example 5 of Embodiment 2.

MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, the lighting device and the lighting fixture according to Embodiments 1 and 2 will be described with reference to the drawings. The drawings referred to in the following Embodiments 1, 2, etc. are schematic drawings, and the sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensions, and the ratios of the sizes and thicknesses between the components also do not necessarily reflect the actual dimensional ratios.

[0014] (Embodiment 1) (1) Outline First, the outline of the lighting device 1 and the lighting fixture 10 according to Embodiment 1 will be described with reference to FIG. 1.

[0015] As shown in FIG. 1, the lighting device 1 according to Embodiment 1 includes a lighting circuit 17, a first surge absorption circuit 11 (surge absorption circuit), a first protection circuit 13, and a second protection circuit 14. The lighting circuit 17 is connected to an external power supply 3 via a first power line L1 and a second power line L2. Based on the first power supplied from the external power supply 3, the lighting circuit 17 generates second power and supplies the generated second power to the light source 2. The first surge absorption circuit 11 is not connected to the second power line L2 and is connected between the external power supply 3 and the ground 4 via the first power line L1. The first protection circuit 13 is connected on the external power supply 3 side with respect to the first surge absorption circuit 11. The second protection circuit 14 is connected on the lighting circuit 17 side with respect to the first surge absorption circuit 11.

[0016] In the lighting device 1 according to Embodiment 1, the first protection circuit 13 and the first surge absorption circuit 11 provided on the external power supply 3 side with respect to the first surge absorption circuit 11 enable protection of the internal circuit against lightning surges. Also, in the lighting device 1 according to Embodiment 1, the second protection circuit 14 provided on the lighting circuit 17 side with respect to the first surge absorption circuit 11 enables protection of other internal circuits (for example, the filter circuit 15) in case of a failure of any internal circuit. That is, according to the lighting device 1 according to Embodiment 1, it is possible to achieve both protection against lightning surges and protection in case of a failure of the internal circuit.

[0017] Further, the lighting fixture 10 according to Embodiment 1 includes the lighting device 1 according to Embodiment 1 and a light source 2 that is lit by the power (second power) supplied from the lighting device 1.

[0018] Since the lighting fixture 10 according to Embodiment 1 includes the lighting device 1 according to Embodiment 1, it is possible to achieve both protection against lightning surges and protection in case of a failure of the internal circuit.

[0019] (2) Details Next, each component of the lighting device 1 and the lighting fixture 10 according to Embodiment 1 will be described with reference to FIG. 1.

[0020] As shown in Figure 1, the lighting fixture 10 according to Embodiment 1 comprises a lighting device 1 and a light source 2. The lighting fixture 10 is, for example, a tunnel light, but is not limited to a tunnel light; for example, it may be a street light or a floodlight. Furthermore, the lighting fixture 10 is not limited to outdoor lighting fixtures such as tunnel lights, street lights and floodlights, but may also be indoor lighting fixtures such as base lights, spotlights and downlights that are installed on the ceiling of a room.

[0021] (2.1) Light source The light source 2 has one or more light-emitting elements 21. In the example in Figure 1, the light source 2 has one light-emitting element 21. The light-emitting element 21 is, for example, an LED (Light-Emitting Diode). The light source 2 is lit by a second power supplied from the lighting circuit 17 of the lighting device 1, which will be described later. The second power is, for example, a DC power of a magnitude sufficient to light up the light source 2.

[0022] (2.2) Lighting device As shown in Figure 1, the lighting device 1 comprises a first surge absorption circuit 11 (surge absorption circuit), a first protection circuit 13, a second protection circuit 14, and a lighting circuit 17. The lighting device 1 further comprises a second surge absorption circuit 12, a filter circuit 15, and a rectifier circuit 16.

[0023] (2.2.1) First surge absorption circuit The first surge absorption circuit 11, as shown in Figure 1, includes, for example, a series circuit of one varistor 111 and one arrester 112. The first surge absorption circuit 11 has a first terminal and a second terminal. The first terminal of the first surge absorption circuit 11 is the terminal on the varistor 111 opposite to the arrester 112 side and is connected to the first output terminal of the external power supply 3 via the first protection circuit 13. The second terminal of the first surge absorption circuit 11 is the terminal on the arrester 112 opposite to the varistor 111 side and is connected to earth 4. The varistor 111 switches from a non-conducting state (high impedance state) to a conducting state (low impedance state) at, for example, a first operating voltage. The arrester 112 switches from a non-conducting state (high impedance state) to a conducting state (low impedance state) at, for example, a second operating voltage higher than the first operating voltage.

[0024] Here, the first power line L1 is connected to the first output terminal of the external power supply 3. Also, the second power line L2 is connected to the second output terminal of the external power supply 3. The first power line L1 and the second power line L2 are power lines connecting the external power supply 3 and the lighting circuit 17. In the example in Figure 1, the first power line L1 includes the third power line L3 and the fourth power line L4. The third power line L3 is a power line connecting the first output terminal of the external power supply 3 and the first terminal of the first surge absorption circuit 11. The fourth power line L4 is a power line connecting the first output terminal of the external power supply 3 and the first input terminal of the lighting circuit 17. That is, the first surge absorption circuit 11 is not connected to the second power line L2, but is connected between the external power supply 3 and the ground 4 via the first power line L1. The external power supply 3 is, for example, an AC power supply of AC350V or higher (for example, AC415V, AC460V). Note that the external power supply 3 is not limited to an AC power supply of AC350V or higher, but may also be an AC power supply of AC200V or AC100V, for example.

[0025] (2.2.2) Second surge absorption circuit The second surge absorption circuit 12 includes, for example, a varistor 121, as shown in Figure 1. The second surge absorption circuit 12 has a first terminal and a second terminal. The first terminal of the second surge absorption circuit 12 is the terminal on the first protection circuit 13 side of the varistor 121 and is connected to the first output terminal of the external power supply 3 via the first protection circuit 13. The second terminal of the second surge absorption circuit 12 is the terminal on the opposite side of the varistor 121 from the first protection circuit 13 side and is connected to the second output terminal of the external power supply 3. The second surge absorption circuit 12 is connected between the first power line L1 and the second power line L2 via the first protection circuit 13. That is, unlike the first surge absorption circuit 11, which is a surge absorption circuit, the second surge absorption circuit 12 is connected between the first power line L1 and the second power line L2.

[0026] (2.2.3) 1st protection circuit The first protection circuit 13 includes, for example, one fuse 131, as shown in Figure 1. The first protection circuit 13 has a first terminal and a second terminal. The first terminal of the first protection circuit 13 is the terminal on the external power supply 3 side of the fuse 131 and is connected to the first output terminal of the external power supply 3. The second terminal of the first protection circuit 13 is the terminal on the first surge absorption circuit 11 side and is connected to the first terminal of the first surge absorption circuit 11. In other words, the first protection circuit 13 (its fuse 131) is connected to the external power supply 3 side of the first surge absorption circuit 11. More specifically, the first protection circuit 13 is connected between the external power supply 3 and the first surge absorption circuit 11 in the third power supply line L3.

[0027] (2.2.4)Second protection circuit The second protection circuit 14 includes, for example, one fuse 141, as shown in Figure 1. The second protection circuit 14 has a first terminal and a second terminal. The first terminal of the second protection circuit 14 is the terminal on the external power supply 3 side of the fuse 141 and is connected to the first output terminal of the external power supply 3. The second terminal of the second protection circuit 14 is the terminal on the lighting circuit 17 side of the fuse 141 and is connected to the first input terminal of the filter circuit 15. In other words, the second protection circuit 14 (its fuse 141) is connected to the lighting circuit 17 side of the first surge absorption circuit 11. More specifically, the second protection circuit 14 is connected between the external power supply 3 and the lighting circuit 17 in the fourth power supply line L4.

[0028] Here, it is preferable that the blowing current value of fuse 131 in the first protection circuit 13 is greater than the blowing current value of fuse 141 in the second protection circuit 14. The blowing current value is the current value when the fuse blows according to its blowing characteristics. The blowing current value of fuse 131 is such that fuse 131 does not blow during the normal operation of the first surge absorption circuit 11, but fuse 131 blows due to a short-circuit current when the first surge absorption circuit 11 fails. The blowing current value of fuse 141 is such that fuse 141 blows due to an increase in current or short-circuit current when a component fails in the internal circuit (filter circuit 15, rectifier circuit 16, lighting circuit 17) on the output side of the first surge absorption circuit 11.

[0029] (2.2.5) Filter Circuits The filter circuit 15 is configured, for example, to remove high-frequency components from the AC voltage from the external power supply 3. The filter circuit 15 has a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The filter circuit 15 also further has a first low-pass filter and a second low-pass filter. The first low-pass filter is connected between the first input terminal and the first output terminal. The second low-pass filter is connected between the second input terminal and the second output terminal.

[0030] The first input terminal of the filter circuit 15 is connected to the second terminal of the second protection circuit 14. The second input terminal of the filter circuit 15 is connected to the second output terminal of the external power supply 3 and the second terminal of the second surge absorption circuit 12. The first output terminal of the filter circuit 15 is connected to the first input terminal of the rectifier circuit 16. The second output terminal of the filter circuit 15 is connected to the second input terminal of the rectifier circuit 16.

[0031] (2.2.6) Rectifier circuit The rectifier circuit 16 is a full-wave rectifier circuit, for example, configured by connecting four diodes in a bridge configuration. The rectifier circuit 16 has a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first input terminal of the rectifier circuit 16 is connected to the first output terminal of the filter circuit 15. The second input terminal of the rectifier circuit 16 is connected to the second output terminal of the filter circuit 15. The first output terminal of the rectifier circuit 16 is connected to the first input terminal of the lighting circuit 17. The second output terminal of the rectifier circuit 16 is connected to the second input terminal of the lighting circuit 17. The rectifier circuit 16 rectifies the AC voltage supplied from the filter circuit 15 into a DC voltage and outputs the rectified DC voltage to the lighting circuit 17.

[0032] Note that the rectifier circuit 16 is not limited to a full-wave rectifier circuit; for example, it may be a half-wave rectifier circuit composed of a single diode.

[0033] (2.2.7) Lighting Circuit The lighting circuit 17 includes, for example, a boost converter and a buck converter. The boost converter boosts the DC voltage supplied from the rectifier circuit 16 and outputs the boosted output voltage to the buck converter. The buck converter steps down the output voltage from the boost converter and supplies the stepped-down output voltage to the light source 2. In Embodiment 1, the power supplied to the light source 2 by the output voltage of the buck converter corresponds to the second power.

[0034] The lighting circuit 17 further includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first input terminal of the lighting circuit 17 is connected to the first output terminal of the rectifier circuit 16. The second input terminal of the lighting circuit 17 is connected to the second output terminal of the rectifier circuit 16. The first and second input terminals of the lighting circuit 17 are also connected to a boost converter. The first output terminal of the lighting circuit 17 is connected to the anode of the light-emitting element 21 of the light source 2. The second output terminal of the lighting circuit 17 is connected to the cathode of the light-emitting element 21 of the light source 2. The first and second output terminals of the lighting circuit 17 are also connected to a step-down converter.

[0035] As shown in Figure 1, the lighting circuit 17 is connected to an external power supply 3 via a first power line L1 and a second power line L2. It generates a second power based on the first power supplied from the external power supply 3 and supplies the generated second power to the light source 2. The first power is, as described above, for example, AC power supplied from the external power supply 3. The second power is, as described above, DC power of a magnitude sufficient to light up the light source 2.

[0036] (3) Operation Next, the operation of the lighting device 1 according to Embodiment 1 will be described.

[0037] During a lightning strike, the induced lightning surge that normally occurs is absorbed between the first power line L1 and the second power line L2 by the conduction of the varistor 121 of the second surge absorption circuit 12, protecting the internal circuit of the lighting device 1. In addition, between the first power line L1 and the earth 4, the induced lightning surge is absorbed by the conduction of the varistor 111 and arrester 112, protecting the internal circuit of the lighting device 1.

[0038] On the other hand, if an induced lightning surge with surge energy exceeding the energy capacity of varistors 111, 121 and arrester 112 is applied, the varistors 111, 121 and arrester 112 will short-circuit, causing a short-circuit current to flow through fuse 131 of the first protection circuit 13, and fuse 131 to blow. At this time, a short-circuit current will also flow through fuse 141 of the second protection circuit 14, causing fuse 141 to blow. As a result, the internal circuit of the lighting device 1 is protected.

[0039] Incidentally, under normal conditions when no induced lightning surge is applied, if, for example, one of the components constituting the filter circuit 15 malfunctions and causes an increase in current or a short circuit current, the fuse 141 of the second protection circuit 14 will blow, protecting the internal circuit of the lighting device 1. At this time, the fuse 131 of the first protection circuit 13 will not blow.

[0040] (4) Effects In the lighting device 1 according to Embodiment 1, the first protection circuit 13 and the first surge absorption circuit 11, which are located on the external power supply 3 side of the first surge absorption circuit 11, enable protection of the internal circuit against lightning surges. Furthermore, in the lighting device 1 according to Embodiment 1, the second protection circuit 14, which is located on the lighting circuit 17 side of the first surge absorption circuit 11, enables protection of other internal circuits in the event of a failure in one of the internal circuits (for example, the filter circuit 15). In other words, the lighting device 1 according to Embodiment 1 makes it possible to achieve both protection against lightning surges and protection in the event of an internal circuit failure.

[0041] In the lighting device 1 according to Embodiment 1, the first protection circuit 13 is connected between the external power supply 3 and the first surge absorption circuit 11 in the third power supply line L3. Therefore, even if the first surge absorption circuit 11 short-circuits due to a lightning surge, for example, the internal circuitry of the lighting device 1 can be protected. Furthermore, in the lighting device 1 according to Embodiment 1, the second protection circuit 14 is connected between the external power supply 3 and the lighting circuit 17 in the fourth power supply line L4. Therefore, even if any of the internal circuits fail and cause an increase in current or a short-circuit current, for example, the internal circuitry of the lighting device 1 can be protected.

[0042] In the lighting device 1 according to Embodiment 1, the first surge absorption circuit 11 includes a series circuit of one varistor 111 and one arrester 112, which makes it possible to improve resistance to lightning surges compared to the case where only one varistor is included.

[0043] In the lighting device 1 according to Embodiment 1, each of the first protection circuit 13 and the second protection circuit 14 includes one or more fuses 131, 141. This makes it possible to protect the internal circuit of the lighting device 1 from short-circuit current in the event of a failure of the first surge absorption circuit 11, or from increased current or short-circuit current in the event of a failure of the internal circuit.

[0044] In the lighting device 1 according to Embodiment 1, the blowing current value of the fuse 131 in the first protection circuit 13 is greater than the blowing current value of the fuse 141 in the second protection circuit 14, making it possible to achieve both protection against lightning surges and protection in the event of an internal circuit failure.

[0045] Unlike the first surge absorption circuit 11, the lighting device 1 according to Embodiment 1 further includes a second surge absorption circuit 12 connected between the first power line L1 and the second power line L2. This makes it possible to protect the internal circuitry of the lighting device 1 from lightning surges occurring between the first power line L1 and the second power line L2.

[0046] Since the lighting fixture 10 according to Embodiment 1 is equipped with the lighting device 1 according to Embodiment 1, it is possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0047] (5) Variant Embodiment 1 is just one of many embodiments of this disclosure. Embodiment 1 can be modified in various ways depending on the design, etc., as long as the objectives of this disclosure are achieved. The following lists some modifications of Embodiment 1. The modifications described below can be combined and applied as appropriate.

[0048] (5.1) Variation 1 The following description of the lighting device 1A and lighting fixture 10A according to Modification 1 will be made with reference to Figure 2. With respect to the lighting device 1A and lighting fixture 10A according to Modification 1, components similar to those of the lighting device 1 and lighting fixture 10 (see Figure 1) according to Embodiment 1 will be denoted by the same reference numerals and their description will be omitted.

[0049] The lighting fixture 10A according to Modification 1 comprises a lighting device 1A and a light source 2, as shown in Figure 2. The lighting device 1A according to Modification 1 also comprises a first surge absorption circuit 11A, a second surge absorption circuit 12, a first protection circuit 13, a second protection circuit 14, a filter circuit 15, a rectifier circuit 16, and a lighting circuit 17.

[0050] The first surge absorption circuit 11A includes a series circuit of two varistors 111 and 113, as shown in Figure 2. The first terminal of the first surge absorption circuit 11A is the terminal on the varistor 111 opposite to the varistor 113 side and is connected to the first output terminal of the external power supply 3 via the first protection circuit 13. The second terminal of the first surge absorption circuit 11A is the terminal on the varistor 113 opposite to the varistor 111 side and is connected to ground 4.

[0051] In the lighting device 1A according to Modification 1, the first surge absorption circuit 11A is not connected to the second power line L2, but is connected between the external power supply 3 and the ground 4 via the first power supply line L1. Furthermore, the first protection circuit 13 is connected to the external power supply 3 side of the first surge absorption circuit 11A, and the second protection circuit 14 is connected to the lighting circuit 17 side of the first surge absorption circuit 11A. This makes it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure, similar to the lighting device 1 according to Embodiment 1.

[0052] Furthermore, since the lighting fixture 10A according to Modification 1 is equipped with the lighting device 1A according to Modification 1, it is possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0053] Furthermore, according to the lighting device 1A of the modified example 1, it is possible to improve resistance to lightning surges compared to the case where only one varistor is included.

[0054] (5.2) Variation 2 The following description of the lighting device 1B and lighting fixture 10B according to Modification 2 will be made with reference to Figure 3. Regarding the lighting device 1B and lighting fixture 10B according to Modification 2, components similar to those in the lighting device 1 and lighting fixture 10 (see Figure 1) according to Embodiment 1 will be denoted by the same reference numerals and their description will be omitted.

[0055] The lighting fixture 10B according to the modified example 2 comprises a lighting device 1B and a light source 2, as shown in Figure 3. The lighting device 1B according to the modified example 2 also comprises a first surge absorption circuit 11B, a second surge absorption circuit 12, a first protection circuit 13, a second protection circuit 14, a filter circuit 15, a rectifier circuit 16, and a lighting circuit 17.

[0056] The first surge absorption circuit 11B includes one varistor 111, as shown in Figure 3. The first terminal of the first surge absorption circuit 11B is the terminal on the first protection circuit 13 side of the varistor 111 and is connected to the first output terminal of the external power supply 3 via the first protection circuit 13. The second terminal of the first surge absorption circuit 11B is the terminal on the opposite side of the varistor 111 from the first protection circuit 13 side and is connected to ground 4.

[0057] In the lighting device 1B according to the modified example 2, the first surge absorption circuit 11B is not connected to the second power line L2, but is connected between the external power supply 3 and the ground 4 via the first power supply line L1. Furthermore, the first protection circuit 13 is connected to the external power supply 3 side of the first surge absorption circuit 11B, and the second protection circuit 14 is connected to the lighting circuit 17 side of the first surge absorption circuit 11B. This makes it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure, similar to the lighting device 1 according to Embodiment 1.

[0058] Furthermore, the lighting fixture 10B according to Modification 2 is equipped with a lighting device 1B according to Modification 2, making it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0059] Furthermore, according to the lighting device 1B of the modified example 2, it is possible to improve resistance to lightning surges compared to the case where only one varistor is included.

[0060] (5.3) Modification 3 The following description of the lighting device 1C and lighting fixture 10C according to Modification 3 will be made with reference to Figure 4. With respect to the lighting device 1C and lighting fixture 10C according to Modification 3, components similar to those of the lighting device 1 and lighting fixture 10 according to Embodiment 1 (see Figure 1) will be denoted by the same reference numerals and their description will be omitted.

[0061] The lighting fixture 10C according to Modification 3 comprises a lighting device 1C and a light source 2, as shown in Figure 4. The lighting device 1C according to Modification 3 further comprises a first surge absorption circuit 11, a second surge absorption circuit 12, a first protection circuit 13, a second protection circuit 14, a filter circuit 15, a rectifier circuit 16, and a lighting circuit 17. The lighting device 1C according to Modification 3 further comprises a third surge absorption circuit 18 and a third protection circuit 19.

[0062] The third surge absorption circuit 18 includes one varistor 181, as shown in Figure 4. The third surge absorption circuit 18 has a first terminal and a second terminal. The first terminal of the third surge absorption circuit 18 is the terminal on the varistor 111 side of the first surge absorption circuit 11 and is connected to the connection point between the varistor 111 and the arrester 112 in the first surge absorption circuit 11. The second terminal of the third surge absorption circuit 18 is the terminal on the opposite side from the varistor 111 side and is connected to the second terminal of the third protection circuit 19, the second terminal of the second surge absorption circuit 12, and the second input terminal of the filter circuit 15.

[0063] The third protection circuit 19 includes a fuse 191. The third protection circuit 19 has a first terminal and a second terminal. The first terminal of the third protection circuit 19 is the terminal on the external power supply 3 side of the fuse 191 and is connected to the second output terminal of the external power supply 3. The second terminal of the third protection circuit 19 is the terminal on the opposite side of the fuse 191 from the external power supply 3 side and is connected to the second terminal of the third surge absorption circuit 18, the second terminal of the second surge absorption circuit 12, and the second input terminal of the filter circuit 15.

[0064] Here, it is preferable that the blowing current value of the fuse 191 of the third protection circuit 19 is equal to or greater than the blowing current value of the fuse 141 of the second protection circuit 14. Also, it is preferable that the blowing current value of the fuse 191 of the third protection circuit 19 is equal to or greater than the blowing current value of the fuse 131 of the first protection circuit 13.

[0065] In other words, the lighting device 1C according to modified example 3 comprises a lighting circuit 17, a first surge absorption circuit 11, a first protection circuit 13, and a second protection circuit 14. The lighting circuit 17 is connected to an external power supply 3 via a first power line L1 and a second power line L2, generates a second power based on the first power supplied from the external power supply 3, and supplies the generated second power to the light source 2. The first surge absorption circuit 11 is connected between the external power supply 3 and the earth 4 via the first power line L1. The first protection circuit 13 is connected to the external power supply 3 side of the first surge absorption circuit 11. The second protection circuit 14 is connected to the lighting circuit 17 side of the first surge absorption circuit 11. The first power line L1 includes a third power line L3 connecting the external power supply 3 and the first surge absorption circuit 11, and a fourth power line L4 connecting the external power supply 3 and the lighting circuit 17. The first protection circuit 13 is connected between the external power supply 3 and the first surge absorption circuit 11 in the third power supply line L3. The second protection circuit 14 is connected between the external power supply 3 and the lighting circuit 17 in the fourth power supply line L4.

[0066] In the lighting device 1C according to the modified example 3, the first surge absorption circuit 11 is connected between the external power supply 3 and the earth 4 via the first power supply line L1. Furthermore, the first protection circuit 13 is connected to the external power supply 3 side of the first surge absorption circuit 11, and the second protection circuit 14 is connected to the lighting circuit 17 side of the first surge absorption circuit 11. This makes it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure, similar to the lighting device 1 according to embodiment 1.

[0067] Furthermore, since the lighting fixture 10C according to Modification 3 is equipped with a lighting device 1C according to Modification 3, it is possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0068] The third protection circuit 19 may be omitted. The first surge absorption circuit 11 may include a varistor connected in series with the varistor 111 instead of the arrester 112. Furthermore, the first surge absorption circuit 11 may include, for example, one varistor. The first protection circuit 13 may include two or more fuses 131, and the second protection circuit 14 may include two or more fuses 141. That is, each of the first protection circuit 13 and the second protection circuit 14 may include one or more fuses 131, 141. The filter circuit 15 may be provided between the first surge absorption circuit 11 and the second surge absorption circuit 12.

[0069] (5.4) Modification 4 The following description of the lighting device 1D and lighting fixture 10D according to Modification 4 will be made with reference to Figure 5. With respect to the lighting device 1D and lighting fixture 10D according to Modification 4, components similar to those of the lighting device 1 and lighting fixture 10 according to Embodiment 1 (see Figure 1) will be denoted by the same reference numerals and their description will be omitted.

[0070] The lighting fixture 10D according to Modification 4 comprises a lighting device 1D and a light source 2, as shown in Figure 5. The lighting device 1D according to Modification 4 further comprises a first surge absorption circuit 11, a second surge absorption circuit 12, a first protection circuit 13, a second protection circuit 14, a filter circuit 15, a rectifier circuit 16, and a lighting circuit 17. The lighting device 1D according to Modification 4 further comprises a third surge absorption circuit 18, a third protection circuit 19, and a fourth protection circuit 20.

[0071] The third surge absorption circuit 18 includes one varistor 181, as shown in Figure 5. The third surge absorption circuit 18 has a first terminal and a second terminal. The first terminal of the third surge absorption circuit 18 is the terminal on the varistor 111 side of the first surge absorption circuit 11 and is connected to the connection point between the varistor 111 and the arrester 112 in the first surge absorption circuit 11. The second terminal of the third surge absorption circuit 18 is the terminal on the opposite side from the varistor 111 side and is connected to the second terminal of the third protection circuit 19 and the second terminal of the second surge absorption circuit 12.

[0072] The third protection circuit 19 includes a fuse 191. The third protection circuit 19 has a first terminal and a second terminal. The first terminal of the third protection circuit 19 is the terminal on the external power supply 3 side of the fuse 191 and is connected to the second output terminal of the external power supply 3. The second terminal of the third protection circuit 19 is the terminal on the opposite side of the fuse 191 from the external power supply 3 side and is connected to the second terminal of the third surge absorption circuit 18 and the second terminal of the second surge absorption circuit 12.

[0073] The fourth protection circuit 20 includes a fuse 201. The fourth protection circuit 20 has a first terminal and a second terminal. The first terminal of the fourth protection circuit 20 is the terminal on the external power supply 3 side of the fuse 201 and is connected to the second output terminal of the external power supply 3. The second terminal of the fourth protection circuit 20 is the terminal on the opposite side of the fuse 201 from the external power supply 3 side and is connected to the second input terminal of the filter circuit 15.

[0074] Here, it is preferable that the blowing current value of fuse 191 in the third protection circuit 19 is the same as the blowing current value of fuse 131 in the first protection circuit 13. Also, it is preferable that the blowing current value of fuse 201 in the fourth protection circuit 20 is the same as the blowing current value of fuse 141 in the second protection circuit 14.

[0075] In the lighting device 1D according to the modified example 4, the first surge absorption circuit 11 is connected between the external power supply 3 and the earth 4 via the first power supply line L1. Furthermore, the first protection circuit 13 is connected to the external power supply 3 side of the first surge absorption circuit 11, and the second protection circuit 14 is connected to the lighting circuit 17 side of the first surge absorption circuit 11. This makes it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure, similar to the lighting device 1 according to Embodiment 1.

[0076] Furthermore, the lighting fixture 10D according to Modification 4 is equipped with a lighting device 1D according to Modification 4, making it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0077] (5.5) Variation 5 The following description of the lighting device 1E and lighting fixture 10E according to Modification 5 will be made with reference to Figure 6. With respect to the lighting device 1E and lighting fixture 10E according to Modification 5, components similar to those of the lighting device 1 and lighting fixture 10 according to Embodiment 1 (see Figure 1) will be denoted by the same reference numerals and their description will be omitted.

[0078] The lighting fixture 10E according to Modification 5 comprises a lighting device 1E and a light source 2, as shown in Figure 6. The lighting device 1E according to Modification 5 further comprises a plurality (three in the illustrated example) of first surge absorption circuits 11, a plurality (three in the illustrated example) of second surge absorption circuits 12, a first protection circuit 13, a second protection circuit 14, a filter circuit 15, a rectifier circuit 16, and a lighting circuit 17. The lighting device 1E according to Modification 5 further comprises a plurality (three in the illustrated example) of third surge absorption circuits 18, a third protection circuit 19, a fourth protection circuit 20, a fifth protection circuit 22, and a sixth protection circuit 23. The plurality of first surge absorption circuits 11, the plurality of second surge absorption circuits 12, and the plurality of third surge absorption circuits 18 correspond one-to-one.

[0079] Each of the multiple third surge absorption circuits 18 includes one varistor 181, as shown in Figure 6. Each third surge absorption circuit 18 has a first terminal and a second terminal.

[0080] The first terminal of the first third surge absorption circuit 18 is the terminal on the varistor 111 side of the first first surge absorption circuit 11, and is connected to the connection point between the varistor 111 and the arrester 112 in the first first surge absorption circuit 11. The second terminal of the first third surge absorption circuit 18 is the terminal on the opposite side from the varistor 111, and is connected to the second terminal of the third protection circuit 19 and the second terminal of the first second surge absorption circuit 12.

[0081] The first terminal of the second third surge absorption circuit 18 is the terminal on the varistor 111 side of the second first surge absorption circuit 11, and is connected to the connection point between the varistor 111 and the arrester 112 in the second first surge absorption circuit 11. The second terminal of the second third surge absorption circuit 18 is the terminal on the opposite side from the varistor 111, and is connected to the second terminal of the sixth protection circuit 23 and the second terminal of the second second surge absorption circuit 12.

[0082] The first terminal of the third surge absorption circuit 18 is the terminal on the varistor 111 side of the third surge absorption circuit 11, and is connected to the connection point between the varistor 111 and the arrester 112 in the third surge absorption circuit 11. The second terminal of the third surge absorption circuit 18 is the terminal on the opposite side from the varistor 111, and is connected to the second terminal of the fourth protection circuit 20, the second terminal of the third surge absorption circuit 12, and the second input terminal of the filter circuit 15.

[0083] The third protection circuit 19 includes a fuse 191. The third protection circuit 19 has a first terminal and a second terminal. The first terminal of the third protection circuit 19 is the terminal on the external power supply 3 side of the fuse 191 and is connected to the second output terminal of the external power supply 3. The second terminal of the third protection circuit 19 is the terminal on the opposite side of the fuse 191 from the external power supply 3 side and is connected to the second terminal of the first third surge absorption circuit 18 and the second terminal of the first second surge absorption circuit 12.

[0084] The fourth protection circuit 20 includes a fuse 201. The fourth protection circuit 20 has a first terminal and a second terminal. The first terminal of the fourth protection circuit 20 is the terminal on the external power supply 3 side of the fuse 201 and is connected to the second output terminal of the external power supply 3. The second terminal of the fourth protection circuit 20 is the terminal on the opposite side of the fuse 201 from the external power supply 3 side and is connected to the second terminal of the third surge absorption circuit 18, the second terminal of the third surge absorption circuit 12, and the second input terminal of the filter circuit 15.

[0085] The fifth protection circuit 22 includes a fuse 221. The fifth protection circuit 22 has a first terminal and a second terminal. The first terminal of the fifth protection circuit 22 is the terminal on the external power supply 3 side of the fuse 221 and is connected to the first output terminal of the external power supply 3. The second terminal of the fifth protection circuit 22 is the terminal on the opposite side of the fuse 221 from the external power supply 3 side and is connected to the first terminal of the second first surge absorption circuit 11 and the first terminal of the second second surge absorption circuit 12.

[0086] The sixth protection circuit 23 includes a fuse 231. The sixth protection circuit 23 has a first terminal and a second terminal. The first terminal of the sixth protection circuit 23 is the terminal on the external power supply 3 side of the fuse 231 and is connected to the second output terminal of the external power supply 3. The second terminal of the sixth protection circuit 23 is the terminal on the opposite side of the fuse 231 from the external power supply 3 side and is connected to the second terminal of the second third surge absorption circuit 18 and the second terminal of the second second surge absorption circuit 12.

[0087] In the lighting device 1E according to modified example 5, each first surge absorption circuit 11 is connected between the external power supply 3 and the ground 4 via the first power supply line L1. Furthermore, the first protection circuit 13 is connected to the external power supply 3 side of the first surge absorption circuit 11, and the second protection circuit 14 is connected to the lighting circuit 17 side of the first surge absorption circuit 11. This makes it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure, similar to the lighting device 1 according to embodiment 1.

[0088] Furthermore, the lighting fixture 10E according to Modification 5 is equipped with a lighting device 1E according to Modification 5, making it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0089] In addition, in the lighting device 1E according to modified example 5, the third first surge absorption circuit 11 and the third third surge absorption circuit 18 may be omitted.

[0090] (5.6) Other variations The following are some other variations.

[0091] In Embodiment 1, the first protection circuit 13 includes one fuse 131, but it may include two or more fuses 131. Also in Embodiment 1, the second protection circuit 14 includes one fuse 141, but it may include two or more fuses 141. In other words, each of the first protection circuit 13 and the second protection circuit 14 may include one or more fuses 131, 141.

[0092] In Embodiment 1, the blowing current value of fuse 131 in the first protection circuit 13 is greater than the blowing current value of fuse 141 in the second protection circuit 14. Conversely, the blowing current value of fuse 131 may be the same as the blowing current value of fuse 141, or it may be less than the blowing current value of fuse 141.

[0093] In Embodiment 1 and Modifications 3-5, the first surge absorption circuit 11 includes a series circuit of one varistor 111 and one arrester 112. In Modification 1, the first surge absorption circuit 11A includes a series circuit of two varistors 111 and 113. In Modification 2, the first surge absorption circuit 11B includes one varistor 111. The number of varistors and arresters is not limited to the above numbers; it may include two or more varistors, or two or more arresters. Furthermore, the first surge absorption circuit may include a TVS (Transient Voltage Suppressor) instead of varistors and arresters, or a series circuit of a Zener diode and a resistor.

[0094] In Embodiment 1, the light-emitting element 21 of the light source 2 is an LED, but the light-emitting element 21 is not limited to an LED; for example, it may be an organic electro-luminescent (OEL) light source.

[0095] (Embodiment 2) The lighting device 1F and lighting fixture 10F according to Embodiment 2 will be described below with reference to Figure 7. With respect to the lighting device 1F and lighting fixture 10F according to Embodiment 2, components similar to those of the lighting device 1 and lighting fixture 10 according to Embodiment 1 (see Figure 1) are denoted by the same reference numerals and their description is omitted.

[0096] The lighting device 1F and lighting fixture 10F according to Embodiment 2 differ from the lighting device 1 and lighting fixture 10 according to Embodiment 1 in that each of the first power line L1 and the second power line L2 is a single power line. Furthermore, the lighting device 1F and lighting fixture 10F according to Embodiment 2 differ from the lighting device 1 and lighting fixture 10 according to Embodiment 1 in that the first surge absorption circuit 11F includes a series circuit of two varistors 111 and 113.

[0097] (1) Composition As shown in Figure 7, the lighting fixture 10F according to Embodiment 2 comprises a lighting device 1F and a light source 2. The lighting device 1F according to Embodiment 2 also comprises a first surge absorption circuit 11F, a second surge absorption circuit 12, a first protection circuit 13, a second protection circuit 14, a filter circuit 15, a rectifier circuit 16, and a lighting circuit 17. Note that the first surge absorption circuit 11F has the same configuration as the first surge absorption circuit 11A according to Modification 1 of Embodiment 1, so its description is omitted here.

[0098] In the lighting device 1F according to Embodiment 2, the first power line L1 and the second power line L2 are each single power lines connecting the external power supply 3 and the lighting circuit 17.

[0099] The first protection circuit 13 and the second protection circuit 14 are connected in series with each other on the first power line L1. The first terminal of the first protection circuit 13 is connected to the first output terminal of the external power supply 3. The second terminal of the first protection circuit 13 is connected to the first terminal of the first surge absorption circuit 11F, the first terminal of the second surge absorption circuit 12, and the first terminal of the second protection circuit 14. The second terminal of the first surge absorption circuit 11F is connected to earth 4. The second terminal of the second protection circuit 14 is connected to the first input terminal of the filter circuit 15. In other words, the first protection circuit 13 is connected between the external power supply 3 and the first surge absorption circuit 11F on the first power line L1. The second protection circuit 14 is connected between the first surge absorption circuit 11F and the lighting circuit 17 on the first power line L1.

[0100] The first terminal of the second surge absorption circuit 12 is connected to the second terminal of the first protection circuit 13, the first terminal of the first surge absorption circuit 11F, and the first terminal of the second protection circuit 14. The second terminal of the second surge absorption circuit 12 is connected to the second output terminal of the external power supply 3 and the second input terminal of the filter circuit 15.

[0101] In Figure 7, the blowing current value of fuse 131 in the first protection circuit 13 is greater than the blowing current value of fuse 141 in the second protection circuit 14. In other words, the blowing current value of a fuse is greater the closer it is to the input side.

[0102] In the lighting device 1F according to Embodiment 2, the first surge absorption circuit 11F is not connected to the second power line L2, but is connected between the external power supply 3 and the ground 4 via the first power supply line L1. Furthermore, the first protection circuit 13 is connected to the external power supply 3 side of the first surge absorption circuit 11F, and the second protection circuit 14 is connected to the lighting circuit 17 side of the first surge absorption circuit 11F. This makes it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure, similar to the lighting device 1 according to Embodiment 1.

[0103] Furthermore, since the lighting fixture 10F according to Embodiment 2 is equipped with the lighting device 1F according to Embodiment 2, it is possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0104] (2) Variant Embodiment 2 is just one of many embodiments of this disclosure. Embodiment 2 can be modified in various ways depending on the design, etc., as long as the objectives of this disclosure are achieved. The following lists some modifications of Embodiment 2. The modifications described below can be combined and applied as appropriate.

[0105] (2.1) Variation 1 The following description of the lighting device 1G and lighting fixture 10G according to Modification 1 will be made with reference to Figure 8. With respect to the lighting device 1G and lighting fixture 10G according to Modification 1, components similar to those of the lighting device 1F and lighting fixture 10F according to Embodiment 2 (see Figure 7) will be denoted by the same reference numerals and their description will be omitted.

[0106] The lighting fixture 10G according to Modification 1 comprises a lighting device 1G and a light source 2, as shown in Figure 8. The lighting device 1G according to Modification 1 also comprises a first surge absorption circuit 11F, a second surge absorption circuit 12, a first protection circuit 13, a second protection circuit 14, a filter circuit 15, a rectifier circuit 16, and a lighting circuit 17. The lighting fixture 10G according to Modification 1 further comprises a third protection circuit 19 and a fourth protection circuit 20.

[0107] The third protection circuit 19 includes a fuse 191. The third protection circuit 19 has a first terminal and a second terminal. The first terminal of the third protection circuit 19 is the terminal on the external power supply 3 side of the fuse 191 and is connected to the second output terminal of the external power supply 3. The second terminal of the third protection circuit 19 is the terminal on the opposite side of the fuse 191 from the external power supply 3 side and is connected to the second terminal of the second surge absorption circuit 12 and the first terminal of the fourth protection circuit 20. Here, it is preferable that the blowing current value of the fuse 191 of the third protection circuit 19 is the same as the blowing current value of the fuse 131 of the first protection circuit 13.

[0108] The fourth protection circuit 20 includes a fuse 201. The fourth protection circuit 20 has a first terminal and a second terminal. The first terminal of the fourth protection circuit 20 is the terminal on the external power supply 3 side of the fuse 201 and is connected to the second terminal of the third protection circuit 19 and the second terminal of the second surge absorption circuit 12. The second terminal of the fourth protection circuit 20 is the terminal on the opposite side of the fuse 201 from the external power supply 3 side and is connected to the second input terminal of the filter circuit 15. That is, as in the lighting device 1G according to modified example 1, protection circuits (first protection circuit 13, second protection circuit 14, third protection circuit 19, fourth protection circuit 20) may be provided on both the first power supply line L1 and the second power supply line L2. Here, it is preferable that the blowing current value of the fuse 201 of the fourth protection circuit 20 is the same as the blowing current value of the fuse 141 of the second protection circuit 14.

[0109] In the lighting device 1G according to the modified example 1, the first surge absorption circuit 11F is not connected to the second power line L2, but is connected between the external power supply 3 and the ground 4 via the first power supply line L1. Furthermore, the first protection circuit 13 is connected to the external power supply 3 side of the first surge absorption circuit 11F, and the second protection circuit 14 is connected to the lighting circuit 17 side of the first surge absorption circuit 11F. This makes it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure, similar to the lighting device 1F according to embodiment 2.

[0110] Furthermore, since the lighting fixture 10G according to Modification 1 is equipped with a lighting device 1G according to Modification 1, it is possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0111] The first surge absorption circuit 11F may include, for example, a series circuit of one varistor and one arrester, or it may include one varistor. The first protection circuit 13 may include two or more fuses 131, and the second protection circuit 14 may include two or more fuses 141. In other words, each of the first protection circuit 13 and the second protection circuit 14 may include one or more fuses 131, 141. The filter circuit 15 may be provided between the first surge absorption circuit 11F and the second surge absorption circuit 12.

[0112] (2.2) Modification 2 The following description of the lighting device 1H and lighting fixture 10H according to Modification 2 will be made with reference to Figure 9. With respect to the lighting device 1H and lighting fixture 10H according to Modification 2, components similar to those of the lighting device 1F and lighting fixture 10F according to Embodiment 2 (see Figure 7) will be denoted by the same reference numerals and their description will be omitted.

[0113] The lighting fixture 10H according to the modified example 2 comprises a lighting device 1H and a light source 2, as shown in Figure 9. The lighting device 1H according to the modified example 2 also comprises a first surge absorption circuit 11F, a second surge absorption circuit 12, a first protection circuit 13, a second protection circuit 14, a filter circuit 15, a rectifier circuit 16, and a lighting circuit 17.

[0114] In the lighting device 1H according to modified example 2, the first power line L1 and the second power line L2 are each single power lines connecting the external power supply 3 and the lighting circuit 17. The first protection circuit 13 is connected between the external power supply 3 and the first surge absorption circuit 11F in the first power line L1. The second protection circuit 14 is connected between the external power supply 3 and the lighting circuit 17 (more precisely, between the external power supply 3 and the filter circuit 15) in the second power line L2.

[0115] The first terminal of the first surge absorption circuit 11F is connected to the second terminal of the first protection circuit 13, the first terminal of the second surge absorption circuit 12, and the first input terminal of the filter circuit 15. The second terminal of the first surge absorption circuit 11F is connected to ground 4. The second terminal of the second surge absorption circuit 12 is connected to the first terminal of the second protection circuit 14 and the second output terminal of the external power supply 3.

[0116] In the lighting device 1H according to the modified example 2, the first surge absorption circuit 11F is not connected to the second power line L2, but is connected between the external power supply 3 and the ground 4 via the first power supply line L1. Furthermore, the first protection circuit 13 is connected to the external power supply 3 side of the first surge absorption circuit 11F, and the second protection circuit 14 is connected to the lighting circuit 17 side of the first surge absorption circuit 11F. This makes it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure, similar to the lighting device 1F according to embodiment 2.

[0117] Furthermore, the lighting fixture 10H according to Modification 2 is equipped with a lighting device 1H according to Modification 2, making it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0118] (2.3) Modification 3 The following description of the lighting device 1I and lighting fixture 10I according to Modification 3 will be made with reference to Figure 10. With respect to the lighting device 1I and lighting fixture 10I according to Modification 3, components similar to those of the lighting device 1F and lighting fixture 10F according to Embodiment 2 (see Figure 7) will be denoted by the same reference numerals and their description will be omitted.

[0119] The lighting fixture 10I according to modified example 3 comprises a lighting device 1I and a light source 2, as shown in Figure 10. The lighting device 1I according to modified example 3 also comprises a first surge absorption circuit 11F, a second surge absorption circuit 12, a first protection circuit 13, a second protection circuit 14, a filter circuit 15, a rectifier circuit 16, and a lighting circuit 17.

[0120] In the lighting device 1I according to modified example 3, the first terminal of the first protection circuit 13 is connected to the first output terminal of the external power supply 3. The second terminal of the first protection circuit 13 is connected to the first terminal of the second surge absorption circuit 12 and the first input terminal of the filter circuit 15. The second terminal of the second surge absorption circuit 12 is connected to the second output terminal of the external power supply 3 and the second input terminal of the filter circuit 15.

[0121] The first terminal of the second protection circuit 14 is connected to the first output terminal of the filter circuit 15 and the first terminal of the first surge absorption circuit 11F. The second terminal of the second protection circuit 14 is connected to the first input terminal of the rectifier circuit 16. The second terminal of the first surge absorption circuit 11F is connected to ground 4. The second output terminal of the filter circuit 15 is connected to the second input terminal of the rectifier circuit 16.

[0122] In other words, the first surge absorption circuit 11F is not connected to the second power line L2, but is connected between the external power supply 3 and the ground 4 via the first power line L1. Also, the first protection circuit 13 is connected closer to the external power supply 3 than the first surge absorption circuit 11F. Furthermore, the second protection circuit 14 is connected closer to the lighting circuit 17 than the first surge absorption circuit 11F. In addition, the first surge absorption circuit 11F and the second protection circuit 14 are connected between the filter circuit 15 and the lighting circuit 17.

[0123] In the lighting device 1I according to the modified example 3, the first surge absorption circuit 11F is not connected to the second power line L2, but is connected between the external power supply 3 and the earth 4 via the first power supply line L1. Furthermore, the first protection circuit 13 is connected to the external power supply 3 side of the first surge absorption circuit 11F, and the second protection circuit 14 is connected to the lighting circuit 17 side of the first surge absorption circuit 11F. This makes it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure, similar to the lighting device 1F according to embodiment 2.

[0124] Furthermore, the lighting fixture 10I according to Modification 3 is equipped with a lighting device 1I according to Modification 3, making it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0125] (2.4) Modification 4 The following description of the lighting device 1J and lighting fixture 10J according to Modification 4 will be made with reference to Figure 11. Regarding the lighting device 1J and lighting fixture 10J according to Modification 4, components similar to those in the lighting device 1I and lighting fixture 10I (see Figure 10) according to Modification 3 will be denoted by the same reference numerals and their explanation will be omitted.

[0126] The lighting fixture 10J according to modified example 4 comprises a lighting device 1J and a light source 2, as shown in Figure 11. The lighting device 1J according to modified example 4 also comprises a first surge absorption circuit 11F, a second surge absorption circuit 12, a first protection circuit 13, a second protection circuit 14, a filter circuit 15, a rectifier circuit 16, and a lighting circuit 17.

[0127] In the lighting device 1J according to modified example 4, the first terminal of the first surge absorption circuit 11F is connected to the second terminal of the first protection circuit 13 and the first input terminal of the filter circuit 15. The second terminal of the first surge absorption circuit 11F is connected to the earth 4. The first terminal of the first protection circuit 13 is connected to the first output terminal of the external power supply 3. In addition, the second input terminal of the filter circuit 15 is connected to the second output terminal of the external power supply 3.

[0128] Furthermore, in the lighting device 1J according to the modified example 4, the first terminal of the second surge absorption circuit 12 is connected to the first output terminal of the filter circuit 15 and the first terminal of the second protection circuit 14. The second terminal of the second surge absorption circuit 12 is connected to the second output terminal of the filter circuit 15 and the second input terminal of the rectifier circuit 16. The second terminal of the second protection circuit 14 is connected to the first input terminal of the rectifier circuit 16.

[0129] In other words, in the lighting device 1I according to modified example 3 and the lighting device 1J according to modified example 4, the positions of the first surge absorption circuit 11F and the second surge absorption circuit 12 with respect to the filter circuit 15 are reversed.

[0130] In the lighting device 1J according to Modification 4, the first surge absorption circuit 11F is not connected to the second power line L2, but is connected between the external power supply 3 and the ground 4 via the first power supply line L1. Furthermore, the first protection circuit 13 is connected to the external power supply 3 side of the first surge absorption circuit 11F, and the second protection circuit 14 is connected to the lighting circuit 17 side of the first surge absorption circuit 11F. This makes it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure, similar to the lighting device 1I according to Modification 3.

[0131] Furthermore, the lighting fixture 10J according to Modification 4 is equipped with a lighting device 1J according to Modification 4, making it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0132] (2.5) Modification 5 The lighting device 1K and lighting fixture 10K according to Modification 5 will be described below with reference to Figure 12. With respect to the lighting device 1K and lighting fixture 10K according to Modification 5, components similar to those of the lighting device 1F and lighting fixture 10F according to Embodiment 2 (see Figure 7) will be denoted by the same reference numerals and their description will be omitted.

[0133] The lighting fixture 10K according to modified example 5 comprises a lighting device 1K and a light source 2, as shown in Figure 12. The lighting device 1K according to modified example 5 also comprises a first surge absorption circuit 11K, a second surge absorption circuit 12, a first protection circuit 13, a second protection circuit 14, a filter circuit 15, a rectifier circuit 16, and a lighting circuit 17. Furthermore, the lighting device 1K according to modified example 5 further comprises a third surge absorption circuit 18 and a third protection circuit 19.

[0134] The first surge absorption circuit 11K includes a series circuit of two varistors 115 and 116, as shown in Figure 12. The first terminal of the first surge absorption circuit 11K is the terminal of varistor 115 opposite to the varistor 116 side and is connected to the first output terminal of the external power supply 3 via the first protection circuit 13. The second terminal of the first surge absorption circuit 11K is the terminal of varistor 116 opposite to the varistor 115 side and is connected to earth 4. In other words, the first surge absorption circuit 11K is connected between the external power supply 3 and earth 4 via the first power line L1.

[0135] The third surge absorption circuit 18 includes one varistor 181. The third surge absorption circuit 18 has a first terminal and a second terminal. The first terminal of the third surge absorption circuit 18 is the terminal on the varistor 115 side of the varistor 181 and is connected to the connection point of the two varistors 115 and 116. The second terminal of the third surge absorption circuit 18 is the terminal on the opposite side of the varistor 181 from the varistor 115 side and is connected to the second output terminal of the external power supply 3 and the first terminal of the third protection circuit 19.

[0136] The third protection circuit 19 includes one fuse 191, as shown in Figure 8. The third protection circuit 19 has a first terminal and a second terminal. The first terminal of the third protection circuit 19 is connected to the second output terminal of the external power supply 3 and the second terminal of the third surge absorption circuit 18. The second terminal of the third protection circuit 19 is connected to the second terminal of the second surge absorption circuit 12 and the second input terminal of the filter circuit 15.

[0137] In other words, the lighting device 1K according to modified example 5 includes a lighting circuit 17, a first surge absorption circuit 11K, a second surge absorption circuit 12, a first protection circuit 13, and a second protection circuit 14. The lighting circuit 17 is connected to an external power supply 3 via a first power line L1 and a second power line L2, generates a second power based on the first power supplied from the external power supply 3, and supplies the generated second power to the light source 2. The first surge absorption circuit 11K is connected between the external power supply 3 and the earth 4 via the first power line L1. The second surge absorption circuit 12 is connected between the first power line L1 and the second power line L2. The first protection circuit 13 is connected closer to the external power supply 3 than the first surge absorption circuit 11. The second protection circuit 14 is connected closer to the lighting circuit 17 than the first surge absorption circuit 11. The first power line L1 is a single power line. The first protection circuit 13 is connected between the external power supply 3 and the first surge absorption circuit 11K in the first power supply line L1. The second protection circuit 14 is connected between the second surge absorption circuit 12 and the lighting circuit 17 in the first power supply line L1.

[0138] In the lighting device 1K according to modified example 5, the first surge absorption circuit 11K is connected between the external power supply 3 and the earth 4 via the first power supply line L1. Furthermore, the first protection circuit 13 is connected to the external power supply 3 side of the first surge absorption circuit 11K, and the second protection circuit 14 is connected to the lighting circuit 17 side of the first surge absorption circuit 11K. This makes it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure, similar to the lighting device 1F according to embodiment 2.

[0139] Furthermore, the lighting fixture 10K according to Modification 5 is equipped with a lighting device 1K according to Modification 5, making it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0140] In the example shown in Figure 12, the first surge absorption circuit 11K and the third surge absorption circuit 18 are connected to the input side of the third protection circuit 19, and the second surge absorption circuit 12 is connected to the output side of the third protection circuit 19. However, the reverse is also possible. That is, the second surge absorption circuit 12 may be connected to the input side of the third protection circuit 19, and the first surge absorption circuit 11K and the third surge absorption circuit 18 may be connected to the output side of the third protection circuit 19.

[0141] (2.6) Other variations The following are some other variations.

[0142] In Embodiment 2, the first protection circuit 13 includes one fuse 131, but may include two or more fuses 131. Also in Embodiment 2, the second protection circuit 14 includes one fuse 141, but may include two or more fuses 141. That is, each of the first protection circuit 13 and the second protection circuit 14 may include one or more fuses 131, 141. Furthermore, in Modification 4, the third protection circuit 19 includes one fuse 191, but may include two or more fuses 191.

[0143] In Embodiment 2, the first surge absorption circuit 11F includes a series circuit of two varistors 111 and 113, but the number of varistors is not limited to two; it may be one or three or more. In addition, the first surge absorption circuit may include one or more arresters in addition to one or more varistors. Furthermore, the first surge absorption circuit may include a TVS instead of varistors and arresters, or it may include a series circuit of a Zener diode and a resistor.

[0144] In Embodiment 2, the light-emitting element 21 of the light source 2 is an LED, but the light-emitting element 21 is not limited to an LED; for example, it may be an organic EL.

[0145] (Aspect) This specification discloses the following aspects:

[0146] The lighting device (1;1A;1B;1F;1G;1H;1I;1J) according to the first embodiment comprises a lighting circuit (17), surge absorption circuits (11;11A;11B;11F), a first protection circuit (13), and a second protection circuit (14). The lighting circuit (17) is connected to an external power supply (3) via a first power line (L1) and a second power line (L2), generates a second power based on the first power supplied from the external power supply (3), and supplies the generated second power to the light source (2). The surge absorption circuits (11;11A;11B;11F) are not connected to the second power line (L2), but are connected between the external power supply (3) and ground (4) via the first power line (L1). The first protection circuit (13) is connected to the external power supply (3) side of the surge absorption circuits (11; 11A; 11B; 11F). The second protection circuit (14) is connected to the lighting circuit (17) side of the surge absorption circuits (11; 11A; 11B; 11F).

[0147] This embodiment makes it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0148] In the lighting device (1;1A;1B) according to the second embodiment, in the first embodiment, the first power line (L1) includes a third power line (L3) connecting an external power supply (3) and a surge absorption circuit (11;11A;11B), and a fourth power line (L4) connecting an external power supply (3) and a lighting circuit (17). The first protection circuit (13) is connected between the external power supply (3) and the surge absorption circuit (11;11A;11B) in the third power line (L3). The second protection circuit (14) is connected between the external power supply (3) and the lighting circuit (17) in the fourth power line (L4).

[0149] According to this embodiment, it is possible to protect the internal circuitry of the lighting device (1;1A;1B).

[0150] In the lighting device (1F;1G;1H;1I;1J) according to the third embodiment, in the first embodiment, the first power line (L1) is a single power line. The first protection circuit (13) is connected between the external power supply (3) and the surge absorption circuit (11F) in the first power line (L1). The second protection circuit (14) is connected between the surge absorption circuit (11F) and the lighting circuit (17) in the first power line (L1).

[0151] According to this embodiment, it is possible to protect the internal circuitry of the lighting device (1F; 1G; 1H; 1I; 1J).

[0152] In the lighting device (1H) according to the fourth embodiment, in the first embodiment, the first power line (L1) and the second power line (L2) are each single power lines. The first protection circuit (13) is connected between the external power supply (3) and the surge absorption circuit (11F) in the first power line (L1). The second protection circuit (14) is connected between the external power supply (3) and the lighting circuit (17) in the second power line (L2).

[0153] According to this embodiment, it is possible to protect the internal circuit of the lighting device (1H).

[0154] The fifth embodiment of the lighting device (1C; 1D; 1E) comprises a lighting circuit (17), a surge absorption circuit (11), a first protection circuit (13), and a second protection circuit (14). The lighting circuit (17) is connected to an external power supply (3) via a first power line (L1) and a second power line (L2), generates a second power based on a first power supplied from the external power supply (3), and supplies the generated second power to a light source (2). The surge absorption circuit (11) is connected between the external power supply (3) and ground (4) via the first power line (L1). The first protection circuit (13) is connected to the external power supply (3) side of the surge absorption circuit (11). The second protection circuit (14) is connected to the lighting circuit (17) side of the surge absorption circuit (11). The first power line (L1) includes a third power line (L3) connecting an external power supply (3) and a surge absorption circuit (11), and a fourth power line (L4) connecting an external power supply (3) and a lighting circuit (17). The first protection circuit (13) is connected between the external power supply (3) and the surge absorption circuit (11) in the third power line (L3). The second protection circuit (14) is connected between the external power supply (3) and the lighting circuit (17) in the fourth power line (L4).

[0155] This embodiment makes it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0156] The lighting device (1K) according to the sixth embodiment comprises a lighting circuit (17), a first surge absorption circuit (11K), a second surge absorption circuit (12), a first protection circuit (13), and a second protection circuit (14). The lighting circuit (17) is connected to an external power supply (3) via a first power line (L1) and a second power line (L2), generates a second power based on the first power supplied from the external power supply (3), and supplies the generated second power to a light source (2). The first surge absorption circuit (11K) is connected between the external power supply (3) and ground (4) via the first power line (L1). The second surge absorption circuit (12) is connected between the first power line (L1) and the second power line (L2). The first protection circuit (13) is connected to the external power supply (3) side of the first surge absorption circuit (11K). The second protection circuit (14) is connected to the lighting circuit (17) side of the first surge absorption circuit (11K). The first power line (L1) is a single power line. The first protection circuit (13) is connected between the external power supply (3) and the first surge absorption circuit (11K) on the first power line (L1). The second protection circuit (14) is connected between the second surge absorption circuit (12) and the lighting circuit (17) on the first power line (L1).

[0157] This embodiment makes it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0158] In the lighting device (1A;1F;1G;1H;1I;1J;1K) according to the seventh embodiment, in any one of the first to sixth embodiments, the surge absorption circuit (11A;11F:11K) includes a series circuit of two varistors (111,113;115,116).

[0159] According to this embodiment, it is possible to improve resistance to lightning surges compared to when the surge absorption circuit includes only one varistor.

[0160] In the lighting device according to the eighth embodiment (1;1C;1D;1E), in any one of the first to sixth embodiments, the surge absorption circuit (11) includes a series circuit of one varistor (111) and one arrester (112).

[0161] According to this embodiment, it is possible to improve resistance to lightning surges compared to when the surge absorption circuit includes only one varistor.

[0162] In the lighting device (1B) according to the ninth embodiment, in any one of the first to sixth embodiments, the surge absorption circuit (11B) includes one varistor (111).

[0163] According to this embodiment, the surge absorption circuit (11B) can be simplified.

[0164] In the lighting device according to the tenth embodiment (1;1A;1B;1C;1D;1E;1F;1G;1H;1I;1J;1K), in any one of the first to ninth embodiments, each of the first protection circuit (13) and the second protection circuit (14) includes one or more fuses (131, 141).

[0165] According to this embodiment, it is possible to protect the internal circuitry of the lighting device (1;1A;1B;1C;1D;1E;1F;1G;1H;1I;1J;1K).

[0166] In the lighting device (1;1A;1B;1C;1D;1E;1F;1G;1H;1I;1J;1K) according to the 11th embodiment, in the 10th embodiment, the blowing current value of one or more fuses (131) in the first protection circuit (13) is greater than the blowing current value of one or more fuses (141) in the second protection circuit (14).

[0167] This embodiment makes it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0168] The lighting device (1I) according to the twelfth embodiment further comprises a filter circuit (15) in any one of the first to eleventh embodiments. A surge absorption circuit (11F) and a second protection circuit (14) are connected between the filter circuit (15) and the lighting circuit (17).

[0169] According to this embodiment, it is possible to remove high-frequency components from the AC voltage supplied from the external power supply (3).

[0170] The lighting device (1;1A;1B;1C;1D;1E;1F;1G;1H;1I;1J;1K) according to the 13th embodiment further comprises a second surge absorption circuit (12) in any one of the first to 12 embodiments. Unlike the first surge absorption circuit (11;11A;11B;11F;11K), which is a surge absorption circuit (11;11A;11B;11F;11K), the second surge absorption circuit (12) is connected between the first power line (L1) and the second power line (L2).

[0171] According to this embodiment, it is possible to protect the internal circuit from overvoltage caused by lightning surges occurring between the first power line (L1) and the second power line (L2).

[0172] A lighting fixture according to the 14th embodiment (10;10A;10B;10C;10D;10E;10F;10G;10H;10I;10J;10K) comprises a lighting device according to any one of the 1st to 13th embodiments (1;1A;1B;1C;1D;1E;1F;1G;1H;1I;1J;1K) and a light source (2).

[0173] This embodiment makes it possible to achieve both protection against lightning surges and protection in the event of internal circuit failure.

[0174] The configurations relating to the second to thirteenth aspects are not essential to the lighting device (1;1A;1B;1C;1D;1E;1F;1G;1H;1i;1J;1K) and can be omitted as appropriate. [Explanation of symbols]

[0175] 1,1A,1B,1C,1D,1E,1F,1G,1H,1I,1J,1K Lighting device 2 light source 3 External power supply 4 Earth 10, 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10I, 10J, 10K Lighting fixtures 11, 11A, 11B, 11F, 11K First Surge Absorption Circuit (Surge Absorption Circuit) 12. Second Surge Absorption Circuit 13 1st protection circuit 14 2nd protection circuit 15 Filter Circuits 17 Lighting Circuit 111,113,115,116 Barista 112 Alesta 131,141 fuses L1 First power line L2 Second Power Line L3 Third Power Line L4 4th power line

Claims

1. A lighting circuit connected to an external power supply via a first power line and a second power line, which generates a second power based on the first power supplied from the external power supply and supplies the generated second power to a light source, A surge absorption circuit is not connected to the second power line, but is connected between the external power supply and ground via the first power line, A first protection circuit connected to the external power supply side of the surge absorption circuit, The system includes a second protection circuit connected to the lighting circuit side of the surge absorption circuit, Lighting device.

2. The first power line is, A third power line connecting the external power supply and the surge absorption circuit, It includes a fourth power line connecting the external power supply and the lighting circuit, The first protection circuit is connected in the third power line between the external power supply and the surge absorption circuit. The second protection circuit is connected between the external power supply and the lighting circuit in the fourth power supply line. The lighting device according to claim 1.

3. The first power line is a single power line, The first protection circuit is connected in the first power line between the external power supply and the surge absorption circuit. The second protection circuit is connected between the surge absorption circuit and the lighting circuit in the first power line. The lighting device according to claim 1.

4. Each of the first power line and the second power line is a single power line. The first protection circuit is connected in the first power line between the external power supply and the surge absorption circuit. The second protection circuit is connected in the second power line between the external power supply and the lighting circuit. The lighting device according to claim 1.

5. A lighting circuit connected to an external power supply via a first power line and a second power line, which generates a second power based on the first power supplied from the external power supply and supplies the generated second power to a light source, A surge absorption circuit connected between the external power supply and ground via the first power line, A first protection circuit connected to the external power supply side of the surge absorption circuit, The system includes a second protection circuit connected to the lighting circuit side of the surge absorption circuit, The first power line is, A third power line connecting the external power supply and the surge absorption circuit, It includes a fourth power line connecting the external power supply and the lighting circuit, The first protection circuit is connected in the third power line between the external power supply and the surge absorption circuit. The second protection circuit is connected between the external power supply and the lighting circuit in the fourth power supply line. Lighting device.

6. A lighting circuit connected to an external power supply via a first power line and a second power line, which generates a second power based on the first power supplied from the external power supply and supplies the generated second power to a light source, A first surge absorption circuit is connected between the external power supply and ground via the first power line, A second surge absorption circuit connected between the first power line and the second power line, A first protection circuit connected to the external power supply side of the first surge absorption circuit, The system includes a second protection circuit connected to the lighting circuit side of the first surge absorption circuit, The first power line is a single power line, The first protection circuit is connected in the first power line between the external power supply and the first surge absorption circuit. The second protection circuit is connected between the second surge absorption circuit and the lighting circuit in the first power line. Lighting device.

7. The surge absorption circuit includes a series circuit of two varistors. A lighting device according to any one of claims 1 to 6.

8. The surge absorption circuit includes a series circuit of one varistor and one arrester. A lighting device according to any one of claims 1 to 6.

9. The surge absorption circuit includes one varistor. A lighting device according to any one of claims 1 to 6.

10. Each of the first protection circuit and the second protection circuit includes one or more fuses. A lighting device according to any one of claims 1 to 6.

11. The blowing current value of one or more fuses in the first protection circuit is greater than the blowing current value of one or more fuses in the second protection circuit. The lighting device according to claim 10.

12. It also features a filter circuit, The surge absorption circuit and the second protection circuit are connected between the filter circuit and the lighting circuit. A lighting device according to any one of claims 1 to 6.

13. Unlike the first surge absorption circuit, which is the surge absorption circuit, the system further comprises a second surge absorption circuit connected between the first power line and the second power line. A lighting device according to any one of claims 1 to 6.

14. A lighting device according to any one of claims 1 to 6, The light source comprises, Lighting fixtures.

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