Light source failure detection device, light source failure detection method, and lighting device

Abstract

To improve accuracy of failure detection when a light source is caused to blink.SOLUTION: A failure detection device that detects the occurrence of a failure in a light source to which a first voltage corresponding to lighting and a second voltage corresponding to turning off are alternately applied from a power supply circuit, includes a controller capable of capturing a current flowing through the light source as a digital signal, and the controller obtains the magnitude of the current for each sampling period set to a length shorter than an application period of each of a first voltage and a second voltage, and detects the occurrence of the failure when a cumulative number in which the magnitude of the current exceeds a preset upper limit value is equal to or greater than a predetermined value.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a light source fault detection device, a light source fault detection method, and a lighting device. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 2007-157423 (Patent Document 1) describes a power supply device configured to detect the total forward voltage of the LED group using a voltage detection circuit, detect the forward current of the LED group using a current detection circuit, and compare these with a reference voltage value in a comparison circuit to detect an abnormality in the LED group and output an abnormality notification signal to turn off a switch provided between the power supply and a DC-DC converter, and notify the outside world of the abnormality via an external notification circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-157423 A Summary of the Invention [Problem to be solved by the invention]

[0004] One of the objectives of a specific embodiment of the present disclosure is to improve the accuracy of detecting a fault in a light source. [Means for solving the problem]

[0005] [1] A fault detection device according to one aspect of the present disclosure, An apparatus for detecting the occurrence of a failure in a light source to which a first voltage corresponding to a light-on state and a second voltage corresponding to a light-off state are alternately applied from a power supply circuit, the apparatus comprising: a controller capable of acquiring a current flowing through the light source as a digital signal; The controller: The magnitude of the current is measured for each sampling period set to be shorter than the application period of each of the first voltage and the second voltage. The average value within the sampling periodand when the cumulative number of times that the magnitude of the current exceeds a preset upper limit value reaches or exceeds a predetermined value, the occurrence of the fault is detected. It is something , the controller detects the occurrence of the fault when the cumulative number becomes equal to or greater than the predetermined value within a predetermined period that is greater than a total value of application periods of the first voltage and the second voltage. This is a fault detection device. [2] A fault detection method according to one aspect of the present disclosure includes: A method for detecting, by a controller, the occurrence of a fault in a light source to which a first voltage corresponding to lighting and a second voltage corresponding to extinguishing are alternately applied from a power supply circuit, the method comprising: The controller acquires a current flowing through the light source as a digital signal; The controller detects the magnitude of the current for each sampling period that is set to be shorter than the application periods of the first voltage and the second voltage. The average value within the sampling period To ask for The controller detects the occurrence of the fault when a cumulative number of times the magnitude of the current exceeds a preset upper limit value becomes equal to or exceeds a predetermined value. detecting the occurrence of the fault when the cumulative number becomes equal to or greater than the predetermined value within a predetermined period that is greater than the total value of application periods of the first voltage and the second voltage; A fault detection method comprising: [3] An illumination device according to one aspect of the present disclosure, The fault detection device according to [1] above; The light source; The lighting device includes:

[0006] According to the above configuration, it is possible to improve the accuracy of detecting a malfunction of the light source. [Brief description of the drawings]

[0007] [Figure 1] Fig. 1(A) is a diagram showing the configuration of a fault detection device and a lighting device including the same according to an embodiment, and Fig. 1(B) is a diagram showing an example of the configuration of a microcomputer that realizes a controller. [Diagram 2] Fig. 2(A) is a waveform diagram showing an example of a drive voltage supplied from a power supply circuit to a light-emitting element. Fig. 2(B) is a waveform diagram showing an example of a voltage signal input to a controller. Fig. 2(C) is a waveform diagram for explaining an example of a sampling period and a sampling timing within the period. [Diagram 3] FIG. 3 is a diagram for explaining an outline of an abnormality detection operation in the failure detection device of this embodiment. [Figure 4] FIG. 4 is a diagram for explaining an outline of an abnormality detection operation in the comparative example. [Diagram 5] Fig. 5(A) is a diagram for explaining upper and lower limit values ​​used in anomaly detection, and Fig. 5(B) is a diagram for explaining upper and lower limit values ​​in a comparative example. [Figure 6] FIG. 6 is a flowchart showing the operation procedure of the controller of the failure detection device. [Figure 7] Fig. 7(A) is a diagram showing a state where a break occurs on the current path of a light-emitting element, and Fig. 7(B) is a diagram showing a state where a short circuit occurs on the current path of a light-emitting element. [Figure 8] FIG. 8 is a waveform diagram showing an example of transient characteristics of a short-circuit current. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Fig. 1(A) is a diagram showing the configuration of a fault detection device according to one embodiment and a lighting device including the same. The lighting device shown in the figure lights up a light-emitting element (light source) 4 such as an LED by a drive voltage supplied from a power supply circuit 2. A current-limiting resistive element 3 connected between the power supply circuit 2 and the light-emitting element 4 is for limiting the magnitude of the current flowing through the light-emitting element 4. The fault detection device 1 detects a fault in the light-emitting element 4 based on the current flowing through the light-emitting element 4. The fault here refers to a break or short circuit in the current path including the light-emitting element 4.

[0009] Although FIG. 1A shows a light source consisting of one light emitting element 4, the light source may be configured by connecting a plurality of light emitting elements in series, in parallel, or in series-parallel.

[0010] The fault detection device 1 includes a controller 10, a current detection circuit 11, a shunt resistance element 12, a resistance element 13, and a capacitance element 14. The shunt resistance element 12 is connected in series between the light-emitting element 4 and a GND terminal (reference potential terminal). The resistance element 13 is connected between the controller 10 and the current detection circuit 11. One end of the capacitance element 14 is connected to a connection point between the resistance element 13 and the controller 10, and the other end is connected to the GND terminal.

[0011] The controller 10 is connected to a current detection circuit 11, and detects any failure occurring in the light-emitting element 4 based on an electric signal (a voltage signal corresponding to the current flowing through the light-emitting element 4) output from the current detection circuit 11. The controller 10 is realized by using a microcomputer (see FIG. 1(B) described later) including a CPU, ROM, RAM, etc., and executing a predetermined program in the CPU.

[0012] The current detection circuit 11 detects the voltage across the shunt resistor element 12. This voltage across the two ends is a voltage signal corresponding to the current flowing through the light-emitting element 4. This voltage signal is smoothed by an RC circuit consisting of a resistor element 13 and a capacitor element 14, converted into a digital signal by an analog-to-digital converter 15 of the controller 10, and input to the controller 10.

[0013] FIG. 1B is a diagram showing an example of the configuration of a microcomputer that realizes the controller. The illustrated microcomputer includes a central processing unit (CPU) 201, a read only memory (ROM) 202, a random access memory (RAM) 203, a storage device 204, and an external interface (I / F) 205, all of which are communicably connected to one another. The CPU 201 operates based on a basic control program read from the ROM 202, and realizes each function of the controller 10 described above by reading and executing a program (application program) 206 stored in the storage device 204. The RAM 203 temporarily stores data to be used during the operation of the CPU 201. The storage device 204 is a non-volatile storage device such as a hard disk or a solid state drive, and stores various data such as the program 206. The external interface 205 is an interface that connects the CPU 201 to an external device. The analog-to-digital conversion unit 15 described above is configured as one of the external interfaces 205.

[0014] FIG. 2(A) is a waveform diagram showing an example of a driving voltage supplied from a power supply circuit to a light emitting element. As shown in the figure, in this embodiment, a driving voltage is assumed in which an on-period, which is a period during which a voltage is applied to turn on the light emitting element 4, and an off-period, which is a period during which a voltage is applied to turn off the light emitting element 4, are alternately repeated. In this embodiment, the on-period and the off-period are set to, for example, the same length of 50 ms, and these on-periods and off-periods together form one period T. The voltage during the on-period is a first voltage corresponding to turning on the light, and in this embodiment, it is a pulse voltage that repeats on and off at a constant period. The voltage during the off-period is a second voltage corresponding to turning off the light, and is typically 0 volts. One on-off period (pulse period) is set to, for example, 4 ms. This corresponds to a pulse frequency of 250 Hz. The example shown in the figure is a pulse voltage with a duty ratio of 50%. The duty ratio is set, for example, between 10 and 90%. The higher the duty ratio, the higher the effective value of the driving voltage supplied to the light emitting element 4, and the brighter the light emitted from the light emitting element 4.

[0015] FIG. 2B is a waveform diagram showing an example of a voltage signal input to the controller. The voltage signal output from the current detection circuit 11 passes through an RC circuit consisting of a resistive element 13 and a capacitive element 14, and is converted into a digital signal by an analog-to-digital converter 15 of the controller 10 and input. The controller 10 calculates an average current value based on the voltage signal for each predetermined sampling period. At this time, for example, in sampling periods S1 and S5, a current flows through the light-emitting element 4 throughout the entire period, so that an accurate average current value can be calculated. However, in cases such as sampling periods S2 and S4, where the switching period between the on period and the off period is included within the period, it is difficult to calculate a correct average current value. Furthermore, in cases such as sampling period S3, where the entire period corresponds to the off period, the current is zero. For this reason, if an abnormality in the light-emitting element 4 is to be detected based on the magnitude of the average current value, it is difficult to determine the reference value. That is, in cases where a driving voltage is applied so that the light-emitting element 4 repeatedly blinks, it is difficult to detect an abnormality by simply comparing the current flowing through the light-emitting element 4 with a reference value.

[0016] FIG. 2(C) is a waveform diagram for explaining an example of a sampling period and a sampling timing within the period. As shown in the figure, in this embodiment, for example, one sampling period is 12 ms. As described above, the driving voltage is a pulse voltage with a pulse period of 4 ms, so that one sampling period includes three pulse periods as shown in the figure. In the analog-to-digital converter 15 of the controller 10 in this embodiment, the voltage signal output from the current detection circuit 11 is captured at a sampling period of 0.5 ms. Eight sampling points are obtained within one pulse period, and 24 sampling points are obtained within one sampling period. Each sampling point is indicated by a black dot in the figure. As described above, by setting the sampling period (12 ms) to be an integer multiple of the pulse period (4 ms), an average current value that matches the pulse period from the start to the end of the pulse period can be obtained regardless of the position at which sampling is started in the driving voltage.

[0017] Fig. 3 is a diagram for explaining an outline of the fault detection operation in the fault detection device of this embodiment. Fig. 3 shows a schematic diagram of the current flowing through the light-emitting element 4, and shows, as an example, a case in which the average current value exceeds an upper limit value during the on-period. In the fault detection device 1 of this embodiment, the average current value is calculated in each sampling period S1, S2, S3, ..., and the calculated average current value is compared with a predetermined upper limit value and a predetermined lower limit value to detect the presence or absence of an abnormality.

[0018] In the illustrated example, the current value exceeds the upper limit near the end of sampling period S1, but the average current value over the entire period does not exceed the upper limit, so the state is detected as "normal." In the next sampling period S2, the current value exceeds the upper limit over the entire period, so the average current value also exceeds the upper limit, and the state is detected as "abnormal." In sampling period S3, the state is detected as "normal," just as in sampling period S1. The states (normal / abnormal) are detected in the same manner thereafter.

[0019] Then, if a predetermined number of "abnormalities" (for example, 5 times) are detected in total during the time period (720 ms in the illustrated example) from when the "abnormality" was first detected until the time when the predetermined period (720 ms in the illustrated example) has elapsed, it is determined that a failure has occurred. Specifically, the controller 10 stops the supply of the drive voltage from the power supply circuit 2 (fail-safe operation). Alternatively, it notifies a host device (not illustrated) of the occurrence of a failure. In this embodiment, since the "abnormality" exceeding the upper limit value is judged by the cumulative number, a blinking control is performed in which an on period and an off period occur alternately, and even if the situation in which the average current value exceeds the upper limit value and the situation in which it does not exceed the upper limit value are repeated, the occurrence of a failure can be reliably detected. The length of the predetermined period is set to be greater than the total value of the on period and the off period of the drive voltage, and is preferably set to, for example, 5 times or more of the total value. In this embodiment, the total value of the on period and the off period of the drive voltage is 100 ms, and the predetermined period is set to 720 ms, which is 7 times the total value.

[0020] Although not shown, when the average current value falls below the lower limit, an "abnormality" is detected every time the average current value falls below the lower limit, and when the number of times this "abnormality" is detected reaches a predetermined number of times in a row (for example, 60 times), a fault is detected. In this way, by judging an "abnormality" that falls below the lower limit based on the number of consecutive times, a fault is not detected when a situation in which the average current value falls below the lower limit intermittently occurs repeatedly, such as in blinking control where on and off periods occur alternately, but a fault is detected only when a fault actually occurs and an "abnormality" is detected continuously.

[0021] FIG. 4 is a diagram for explaining an outline of the abnormality detection operation of the comparative example. In this comparative example, the occurrence of a fault is detected only when the detection of an "abnormality" caused by the average current value exceeding the upper limit value reaches a predetermined number of times (for example, 60 times) in succession within a predetermined period (720 ms in the illustrated example). In addition, if a "normality" is detected even once without reaching the predetermined number of times, the detection count is reset. In addition, the detection count is reset when a predetermined period has passed. This is because emphasis is placed on continuous reproducibility in the detection of an "abnormality". For this reason, in the case where the average current value periodically drops with the blinking control as shown in FIG. 3, it is not possible to accurately determine a fault.

[0022] FIG. 5(A) is a diagram for explaining the upper limit and lower limit used for abnormality detection. FIG. 5(B) is a diagram for explaining the upper limit and lower limit of a comparative example. In this embodiment, the upper limit (upper limit threshold) and the lower limit (lower limit threshold) are set according to the duty ratio (Duty) of the drive voltage. Specifically, the normal current setting value and the upper limit are set to be larger in proportion to the duty ratio, and the upper limit is set to, for example, a value 20% higher than the normal current setting value based on the designed normal current setting value. Compared to the upper limit of the comparative example corresponding to continuous lighting shown in FIG. 5(B), in this embodiment, the upper limit is shifted to the larger side. As a result, in this embodiment, detection of "abnormality" due to exceeding the upper limit value is less likely to occur compared to the comparative example. In addition, in this embodiment, the lower limit is set to a constant value regardless of the duty ratio. This lower limit is set to a value larger than zero in consideration of a weak current generated by EMC noise, etc., in order to have resistance to erroneous detection due to the weak current. Such upper limit and lower limit are stored in advance in a memory as a data table available in the controller 10, for example.

[0023] Fig. 6 is a flowchart showing the operation procedure of the controller of the fault detection device. The contents of information processing in the controller 10 of the fault detection device 1 will be described below with reference to Fig. 6. Note that the order of operations can be changed as appropriate as long as no contradiction or inconsistency occurs in the control results, and other operations not mentioned here can be added, and such embodiments are not excluded.

[0024] The controller 10 calculates the average current value within the sampling period based on the voltage signal captured from the current detection circuit 11 (step S11). As described above, as an example, the sampling period is 12 ms, the sampling cycle is 0.5 ms, and voltage signals corresponding to 24 current values ​​are obtained within the sampling period, and the average current value is obtained based on these (see FIG. 2(C)).

[0025] Next, the controller 10 compares the average current value with a predetermined upper limit value, and if it does not exceed the upper limit value (step S12; NO), it compares the average current value with a predetermined lower limit value, and if it does not fall below the lower limit value (step S13; NO), it returns to step S11 and continues the subsequent processes. If this loop continues, there is no abnormality in the current path of the light-emitting element 4, and the light-emitting element 4 is normally repeating the blinking operation.

[0026] If the average current value is below the lower limit (step S13; YES), the controller 10 detects an "abnormality" related to the lower limit and records the number of abnormality detections in a memory (not shown) (step S14). For example, the number of abnormality detections related to the lower limit is recorded as "1" for the first detection, "2" for the second detection, and so on.

[0027] Next, the controller 10 distinguishes between cases depending on whether the number of consecutive detections of "abnormality" related to the lower limit has reached 60, and if the number of consecutive "abnormalities" has not reached 60 (step S15; NO), the controller 10 returns to step S11 and continues the subsequent processing.

[0028] If the number of consecutive detections of "abnormality" regarding the lower limit reaches 60 (step S15; YES), the controller 10 controls the power supply circuit 2 to set the drive voltage to zero (step S16). The controller 10 also notifies an upper device (not shown) of the occurrence of a failure as appropriate (step S17).

[0029] On the other hand, if the average current value exceeds the upper limit value (step S12; YES), the controller 10 detects an "abnormality" related to the upper limit value and records the number of abnormality detections in a memory (not shown) (step S18). For example, the number of abnormality detections related to the upper limit value is recorded as "1" for the first detection, "2" for the second detection, and so on.

[0030] Next, if the cumulative number of detections of an "abnormality" related to the upper limit value reaches five (step S19; YES), the controller 10 controls the power supply circuit 2 to set the drive voltage to zero (step S16), as described above, and appropriately notifies the user of the occurrence of a fault (step S17).

[0031] If the cumulative number of detections of "abnormality" regarding the upper limit has not reached five (step S19; NO), and if 720 ms has elapsed since the first detection of "abnormality" regarding the upper limit (step S20; YES), the controller 10 resets the cumulative number to zero (step S21). After resetting the cumulative number, or if 720 ms has not elapsed (step S20; NO), the controller 10 returns to step S11 and continues the subsequent processing.

[0032] According to the above operation procedure, when a break occurs on the current path of the light-emitting element 4 as shown in Fig. 7(A), the current becomes zero or close to zero, resulting in a situation in which "abnormalities" related to the lower limit continue, and the process loops between steps S11 to S15 in the flowchart shown in Fig. 6, and if "abnormalities" are detected 60 times in succession, the fail-safe process of steps S16 and S17 is executed. Note that if no break occurs, the current temporarily becomes zero during the off period, but the current returns to a normal value during the subsequent on period, so that "abnormalities" do not continue and the fail-safe process is not executed erroneously.

[0033] 7B, when a short circuit occurs that forms a current path parallel to the current path of the light-emitting element 4, no current flows through the light-emitting element 4, but a large short-circuit current flows through the shunt resistance element 12. This short-circuit current flows intermittently in accordance with the on-period, resulting in a situation in which an "abnormality" related to the upper limit value occurs intermittently, and the process loops between steps S11, S12, and S18 to S20 in the flowchart shown in FIG. 6, and a cumulative five "abnormalities" are detected, causing the fail-safe process of steps S16 and S17 to be executed.

[0034] FIG. 8 is a waveform diagram showing an example of the transient characteristics of a short-circuit current. With reference to FIG. 8, abnormality detection during a short circuit will be described in more detail. Here, a blinking operation is assumed in which the on-period and off-period are each set to 50 ms, and the duty ratio of the pulse voltage during the on-period is set to 50%. As design conditions, when the current at a duty ratio of 100% under normal conditions has a design tolerance of 1A±20%, during the lighting period of the blinking operation at a duty ratio of 50%, a calculated current of 0.5A (typ), which is 50% of 1A, flows, and it has been experimentally determined that the short-circuit current flows at a duty ratio of 100% to be 2A.

[0035] As shown in the figure, a short-circuit current starts to flow at the start of the on-period. Here, the duty ratio is 50%, so the short-circuit current is 1 A. The RC circuit consisting of the resistive element 13 and the capacitive element 14 causes the voltage signal input to the controller 10 to have a transient characteristic according to the RC time constant, but the voltage eventually rises to a level equivalent to a short-circuit current of 1 A. Originally, the normal current is 0.5 A ± 20% at a duty ratio of 50%, so the upper limit of the abnormal current is set to 0.7 A, but the short-circuit current becomes larger than this upper limit. If this upper limit is set to 0.9 A for a duty ratio of 50%, the short-circuit current of 1 A will exceed this upper limit and can be detected as an "abnormality". In this way, by setting the upper limit (upper limit threshold) of the abnormal current value during blinking operation to be even higher than the upper limit during constant lighting operation, abnormality detection during blinking operation can be made more reliable. Since no abnormal current flows during blinking operation in the normal state, the upper limit of the abnormal current set here will not be exceeded, and no false detection will occur.

[0036] Here, as described above, the short circuit current at a duty ratio of 50% is 1A, and although it has a transient characteristic according to the RC time constant, the short circuit current eventually rises to a magnitude equivalent to this 1A. If each sampling period S1, etc. is 12ms, the on-period is 50ms, and the upper limit value of abnormality detection is 0.9A, the sampling period must start when the voltage signal rises to a magnitude equivalent to this 0.9A, and an average current value of 0.9A or more must be obtained. In this case, it is necessary to reliably obtain a voltage signal equivalent to 0.9A or more at a point 12ms before the end of the on-period of 50ms (see point a in Figure 8). Furthermore, since the 12ms sampling period and the on-period are not synchronized and are random, in order to detect the short circuit current more reliably, it is sufficient to correspond two sampling periods to the latter half of the on-period. This makes it possible to reliably detect an abnormal current at least once (see point b in Figure 8). Since the on-period is 50 ms and the period for two samplings is 24 ms, the magnitude of the upper limit value should be set so that the current value exceeds the upper limit value within 26 ms (=50 ms-24 ms).

[0037] Here, the sampling period needs to be set to be short relative to the on-period, but we need to consider how short it should be. If you want to ensure that half of the on-period remains even after subtracting two sampling periods from the on-period, then it is best to set the length of the sampling period to 1 / 4 or less of the on-period. In the above example, the on-period is 50 ms and the sampling period is 12 ms, so this satisfies the condition of 1 / 4 or less. Furthermore, by making this sampling period an integer multiple of the pulse period, it is possible to reduce current measurement errors. In the above example, the pulse period is 4 ms and the sampling period is set to 3 times this pulse period, so this satisfies the condition of an integer multiple.

[0038] According to the embodiment as described above, it is possible to improve the accuracy of failure detection even when the light source is caused to blink.

[0039] The present disclosure is not limited to the above-mentioned embodiment, and can be modified in various ways within the scope of the present disclosure. For example, the wavelength of the emitted light from the light-emitting element is not particularly limited, and may be visible light or invisible light. For example, the present disclosure may be applied to failure detection in an inspection device using a light-emitting element with a non-visible light wavelength used in the medical field, or to failure detection of a light-emitting element used for cultivation lighting of agricultural crops. In addition, the present disclosure may be applied to lighting devices in general that use a light-emitting element that is operated to blink.

[0040] In the above embodiment, the voltage during the ON period is a pulse voltage that periodically repeats ON and OFF within the engine, but the ON voltage may be constant throughout the ON period, which corresponds to a duty ratio of 100%. [Explanation of symbols]

[0041] 1: fault detection device, 2: power supply circuit, 3: current limiting resistance element, 4: light emitting element, 10: controller, 11: current detection circuit, 12: shunt resistance element, 13: resistance element, 14: capacitance element, 15: analog-to-digital converter

Claims

1. 1. An apparatus for detecting occurrence of a failure in a light source to which a first voltage corresponding to a light-on state and a second voltage corresponding to a light-off state are alternately applied from a power supply circuit, comprising: a controller capable of acquiring a current flowing through the light source as a digital signal; The controller: an average value within a sampling period is calculated as the magnitude of the current for each sampling period, the average value being set to be shorter than the application period of each of the first voltage and the second voltage; and when a cumulative number of times that the magnitude of the current exceeds a preset upper limit value reaches or exceeds a predetermined value, occurrence of the fault is detected; the controller detects the occurrence of the fault when the cumulative number becomes equal to or greater than the predetermined value within a predetermined period that is greater than a total value of application periods of the first voltage and the second voltage. Fault detection device.

2. A device for detecting the occurrence of a fault in a light source to which a first voltage corresponding to lighting and a second voltage corresponding to extinguishing are alternately applied from a power supply circuit, comprising: a controller capable of acquiring a current flowing through the light source as a digital signal; The controller: an average value within a sampling period is calculated as the magnitude of the current for each sampling period, the average value being set to be shorter than the application periods of the first voltage and the second voltage; and when a cumulative number of times that the magnitude of the current exceeds a preset upper limit value reaches a predetermined value or more, the occurrence of the fault is detected; The length of the application period of the first voltage is equal to the length of the application period of the second voltage. Fault detection device.

3. An apparatus for detecting the occurrence of a fault in a light source to which a first voltage corresponding to lighting and a second voltage corresponding to extinguishing are alternately applied from a power supply circuit, comprising: a controller capable of acquiring a current flowing through the light source as a digital signal; The controller: a magnitude of the current is obtained for each sampling period set to be shorter than the application period of each of the first voltage and the second voltage, and occurrence of the fault is detected when a cumulative number of times that the magnitude of the current exceeds a preset upper limit value becomes equal to or greater than a predetermined value, the first voltage is a pulse voltage; The magnitude of the current is an average value within the sampling period. Fault detection device.

4. The controller performs control to stop the voltage supply operation of the power supply circuit when the occurrence of the failure is detected. A fault detection device according to any one of claims 1 to 3.

5. The sampling period is equal to or less than ¼ of the application period of the first voltage. A fault detection device according to any one of claims 1 to 4.

6. The controller resets the cumulative number if the cumulative number does not reach the predetermined value within the predetermined period. The fault detection device according to claim 1 .

7. The length of the application period of the first voltage and the application period of the second voltage are equal.

4. The fault detection device according to claim 1 or 3.

8. The first voltage is a pulse voltage.

3. The fault detection device according to claim 1 or 2.

9. 1. A method for detecting, by a controller, the occurrence of a fault in a light source to which a first voltage corresponding to lighting and a second voltage corresponding to extinguishing are alternately applied from a power supply circuit, the method comprising: The controller acquires a current flowing through the light source as a digital signal; the controller calculates an average value of the magnitude of the current during each sampling period, the average value being set to be shorter than the application periods of the first voltage and the second voltage; the controller detects the occurrence of the fault when a cumulative number of times the magnitude of the current exceeds a preset upper limit value becomes equal to or greater than a predetermined value, and the controller detects the occurrence of the fault when the cumulative number becomes equal to or greater than the predetermined value within a predetermined period that is greater than a total value of application periods of the first voltage and the second voltage; The fault detection method includes:

10. A fault detection device according to any one of claims 1 to 8, The light source; A lighting device comprising:

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