Lighting device

Abstract

To accurately detect a zero cross point even when a filter circuit is used.SOLUTION: The lighting device 10 includes a zero crossing detection circuit 4, a control circuit 1, and a filter circuit 2. The zero cross detection circuit 4 detects a zero cross point of the volts alternating current AC1 supplied from the AC power source V1. A zero cross detection signal S1, which is a detection result of the zero cross detection circuit 4, is input to the control circuit 1. The filter circuit 2 is connected between the zero crossing detection circuit 4 and the control circuit 1. The control circuit 1 executes zero cross point determination processing in which a third timing between the first timing and the second timing is set as a zero cross point when a time from the first change point to the second change point is set as a first time and a time of 1 / 2 of the first time is set as a second time.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a lighting device, and more particularly to a lighting device including a zero-crossing detection circuit and a filter circuit. [Background technology]

[0002] The power control device described in Patent Document 1 includes a zero-cross detector, a trigger pulse generating circuit, and a power controller. The zero-cross detector detects zero-cross points of an AC power supply. The trigger pulse generating circuit generates a trigger pulse for ignition phase control using the rising edge of the output pulse from the zero-cross detector as a reference timing. The power controller controls the ignition phase using the trigger pulse. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-14525 Summary of the Invention [Problem to be solved by the invention]

[0004] In a power control device (lighting device) such as that described in Patent Document 1, if a filter circuit for suppressing erroneous detection due to noise is connected, for example, there are cases where the zero-crossing point cannot be detected accurately.

[0005] An object of the present disclosure is to provide a lighting device that can accurately detect zero-crossing points even when a filter circuit is used. [Means for solving the problem]

[0006] A lighting device according to one aspect of the present disclosure includes a zero-crossing detection circuit, a control circuit, and a filter circuit. The zero-crossing detection circuit detects zero-crossing points of an AC voltage supplied from an AC power source. The control circuit receives a zero-crossing detection signal, which is a detection result of the zero-crossing detection circuit. The filter circuit is connected between the zero-crossing detection circuit and the control circuit. The control circuit executes a zero-crossing point determination process. In the zero-crossing point determination process, if a first time is defined as the time from a first change point to a second change point, and a second time is defined as half the first time, a third time between a first timing and a second timing is defined as the zero-crossing point. At the first change point, the signal value of the zero-crossing detection signal changes to exceed a threshold value. At the second change point, the signal value changes to fall below the threshold value. The first timing corresponds to the first change point. The second timing is defined as the first timing plus the second time. [Effects of the Invention]

[0007] According to the lighting device according to one aspect of the present disclosure, it is possible to accurately detect zero-crossing points even when a filter circuit is used. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic circuit diagram of a lighting device according to the first embodiment. [Figure 2] FIG. 2 is a timing chart illustrating the main parts of the lighting device. [Figure 3] FIG. 3 is a schematic circuit diagram of a lighting device according to the second embodiment. [Figure 4] FIG. 4 is a schematic circuit diagram of a lighting device according to the third embodiment. [Figure 5] FIG. 5 is a schematic circuit diagram of a lighting device according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, lighting devices according to embodiments 1 to 4 will be described with reference to the drawings. The drawings referred to in the following embodiments 1 to 4 are schematic diagrams, and the sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensions, and the size ratios and thickness ratios between the components do not necessarily reflect the actual dimensional ratios.

[0010] (Embodiment 1) (1) Overview First, an overview of a lighting device 10 according to the first embodiment will be described with reference to FIGS.

[0011] As shown in FIG. 1, the lighting device 10 according to the first embodiment includes a zero-crossing detection circuit 4, a control circuit 1, and a filter circuit 2. The zero-crossing detection circuit 4 detects a zero-crossing point ZP1 (see FIG. 2) of an AC voltage V1 supplied from an AC power source AC1. The control circuit 1 receives a zero-crossing detection signal S1, which is the detection result of the zero-crossing detection circuit 4. The filter circuit 2 is connected between the zero-crossing detection circuit 4 and the control circuit 1. The control circuit 1 executes a zero-crossing point determination process (see FIG. 2) to determine a third timing between the first timing and the second timing as the zero-crossing point ZP1, where T1 is the time from the first change point to the second change point, and T2 is half the time of T1. At the first change point, the signal value of the zero-crossing detection signal S1 changes to exceed a threshold value th1. At the second change point, the signal value changes to fall below the threshold value th1. The first timing corresponds to the first change point. The second timing is the first timing plus a second time T2.

[0012] In the lighting device 10 according to the first embodiment, a third timing between a first timing corresponding to the first change point and a second timing obtained by adding a second time T2 to the first timing is set as the zero-crossing point ZP1. That is, in the lighting device 10 according to the first embodiment, by setting the third timing before the second timing as the zero-crossing point ZP1, it is possible to suppress deviation in the detection timing by the filter circuit 2. In short, the lighting device 10 according to the first embodiment makes it possible to accurately detect the zero-crossing point ZP1 even when the filter circuit 2 is used.

[0013] (2)Details Next, components of the lighting device 10 according to the first embodiment will be described with reference to FIGS.

[0014] 1, the lighting device 10 according to the first embodiment includes a control circuit 1, a filter circuit 2, a rectifier circuit 3, and a zero-crossing detection circuit 4. The lighting device 10 according to the first embodiment further includes a plurality of resistors R2 and R3 (two in the illustrated example).

[0015] (2.1) Filter circuit 1, the filter circuit 2 includes a resistor R1 and a capacitor C1. In the present embodiment, as an example, the filter circuit 2 is a low-pass filter (RC filter) configured with the resistor R1 and the capacitor C1.

[0016] A first terminal of the resistor R1 is connected to a first terminal of a light receiving element of a photocoupler 40 of the zero-cross detection circuit 4, which will be described later. The first terminal of the resistor R1 is also connected (pulled up) to a power supply Vdd via a resistor R3. A second terminal of the resistor R1 is connected to the control circuit 1. That is, the resistor R1 is connected in series between the zero-cross detection circuit 4 and the control circuit 1.

[0017] A first terminal of the capacitor C1 is connected to a second terminal of the resistor R1. The first terminal of the capacitor C1 is also connected to the control circuit 1. The second terminal of the capacitor C1 is connected to ground. The second terminal of the capacitor C1 is also connected to a second terminal of the light-receiving element of the photocoupler 40. That is, the capacitor C1 is connected in parallel with the resistor R1. More specifically, the capacitor C1 is connected in parallel with the resistor R1 via the light-receiving element of the photocoupler 40.

[0018] As described above, in the lighting device 10 according to the first embodiment, the filter circuit 2 is connected between the zero-crossing detection circuit 4 and the control circuit 1.

[0019] The filter circuit 2 is not limited to a configuration of the resistor R1 and the capacitor C1, but may be configured, for example, of an inductor and a capacitor, or may be configured only of an inductor.

[0020] (2.2) Rectifier circuit The rectifier circuit 3 is, for example, a full-wave rectifier circuit in which a plurality of (for example, four) diodes are connected in a bridge configuration. The rectifier circuit 3 rectifies the AC voltage V1 supplied from the AC power supply AC1. Note that the rectifier circuit 3 is not limited to a full-wave rectifier circuit, and may be, for example, a half-wave rectifier circuit composed of a single diode.

[0021] (2.3) Zero-cross detection circuit As shown in FIG. 1, the zero-crossing detection circuit 4 includes a photocoupler 40. The photocoupler 40 includes a light-emitting element and a light-receiving element. A first terminal (anode) of the light-emitting element is connected to a first output terminal of the rectifier circuit 3 via a resistor R2. A second terminal (cathode) of the light-emitting element is connected to a second output terminal of the rectifier circuit 3. A first terminal of the light-receiving element is connected to the control circuit 1 via a resistor R1 of the filter circuit 2. A second terminal of the light-receiving element is connected to ground. In addition, the second terminal of the light-receiving element is connected to a second terminal of the capacitor C1 of the filter circuit 2.

[0022] The zero-crossing detection circuit 4 detects a zero-crossing point ZP1 (see FIG. 2) of the AC voltage V1 supplied from the AC power supply AC1. More specifically, the zero-crossing detection circuit 4 outputs a zero-crossing detection signal S1 (see FIG. 2) whose signal value is "1" when the absolute value of the AC voltage V1 is within a predetermined range (±Vth) that includes the zero-crossing point ZP1. That is, as shown in FIG. 2, the zero-crossing detection circuit 4 outputs the zero-crossing detection signal S1 whose signal value is "1" during the period from time t31, when the absolute value of the AC voltage V1 falls below the absolute value of a first threshold value +Vth, to time t34, when the absolute value of the AC voltage V1 exceeds the absolute value of a second threshold value −Vth. The zero-crossing detection signal S1 output from the zero-crossing detection circuit 4 is input to the control circuit 1 via the filter circuit 2.

[0023] (2.4) Control circuit The control circuit 1 can be realized, for example, by a computer system having one or more processors and one or more memories. That is, the one or more processors execute a program recorded in one or more memories of the computer system, thereby functioning as the control circuit 1. The program may be pre-recorded in the memory of the computer system, or may be provided via a telecommunications line such as the Internet, or may be recorded on a non-transitory recording medium such as a memory card and provided.

[0024] As shown in Fig. 1, the control circuit 1 is connected to the zero-cross detection circuit 4 via the filter circuit 2. Therefore, a zero-cross detection signal S1 (see Fig. 2), which is the detection result of the zero-cross detection circuit 4, is input to the control circuit 1. More specifically, the zero-cross detection signal S1 that has passed through the filter circuit 2 is input to the control circuit 1.

[0025] Here, as described above, the zero-cross detection signal S1 output from the zero-cross detection circuit 4 is input to the control circuit 1 via the filter circuit 2. Therefore, as shown in FIG. 2, it changes smoothly (i.e., does not change abruptly) at both the rising and falling edges of the signal. For this reason, if, as in the prior art, the timing obtained by adding half of the time from the rising edge to the falling edge of the signal to the rising-edge timing of the signal is taken as the zero-cross point, the zero-cross point may shift. Therefore, in the present embodiment, the control circuit 1 executes a zero-cross point determination process described later.

[0026] In the zero-cross point determination process, the control circuit 1 sets the third timing between the first timing and the second timing as the zero-cross point ZP1. The first timing is the timing corresponding to the first change point. The first change point is a point where, as shown in FIG. 2, the signal value of the zero-cross detection signal S1 changes so as to exceed the threshold value th1 (0 < th1 < 1). In the example of FIG. 2, the first timing corresponds to time t32. The second timing is the timing obtained by adding the second time T2 to the first timing. The second time T2 is half of the first time T1, and the first time T1 is the time from the first change point to the second change point. The second change point is a point where, as shown in FIG. 2, the signal value of the zero-cross detection signal S1 changes so as to fall below the threshold value th1. In the example of FIG. 2, the first time T1 corresponds to the time from time t32 to time t35, and the second time T2 corresponds to the time from time t32 to time t33.

[0027] As described above, the third timing is the timing between the first timing and the second timing. In the example of FIG. 2, it is the timing that is T3 earlier than the second timing. That is, the third time T3 corresponds to the time from the second timing to the third timing. It is preferable that the third time T3 is greater than 0 and less than the second time T2.

[0028] The control circuit 1 preferably determines the third time T3 based on the time constant of the filter circuit 2. That is, the third time T3 is preferably determined based on the time constant of the filter circuit 2. This makes it possible to improve the detection accuracy of the zero-crossing point ZP1.

[0029] Here, it is preferable that the control circuit 1 executes the above-described zero-crossing point determination process n times (n is an integer equal to or greater than 2). In this case, the control circuit 1 calculates an average value of the first times T1 based on the n first times T1 calculated in the n zero-crossing point determination process. Thereafter, the control circuit 1 calculates an average value of the second times T2 from the average values ​​of the first times T1. Then, in the (n+1)th zero-crossing point determination process, the control circuit 1 determines the third timing using the average value of the second times T2 and the third time T3. More specifically, the control circuit 1 determines the third timing to be the time obtained by subtracting the third time T3 from time t33, which is obtained by adding the average value of the second times T2 to time t32, which is the starting point of the first time T1.

[0030] For example, assume that n=8. In this case, the control circuit 1 calculates the average value of the first times T1 based on the eight first times T1 calculated in eight zero-crossing point determination processes. Thereafter, the control circuit 1 calculates the average value of the second times T2 from the average values ​​of the first times T1. Then, in the ninth zero-crossing point determination process, the control circuit 1 determines the third timing (zero-crossing point ZP1) using the average value of the second times T2 calculated based on the eight first times T1 and the third time T3. This makes it possible to accurately determine the third timing (zero-crossing point ZP1).

[0031] Note that while FIG. 2 illustrates a period in which the AC voltage V1 decreases from the first threshold value +Vth toward the second threshold value −Vth, the same applies to a period in which the AC voltage V1 increases from the second threshold value −Vth toward the first threshold value +Vth.

[0032] Furthermore, when calculating the average value of the second times T2, the control circuit 1 may calculate the average value of the second times T2 based on n second times T2.

[0033] (3) Effects In the lighting device 10 according to the first embodiment, a third timing between a first timing corresponding to the first change point and a second timing obtained by adding a second time T2 to the first timing is set as the zero-crossing point ZP1. That is, in the lighting device 10 according to the first embodiment, by setting the third timing before the second timing as the zero-crossing point ZP1, it is possible to suppress deviation in the detection timing by the filter circuit 2. In short, the lighting device 10 according to the first embodiment makes it possible to accurately detect the zero-crossing point ZP1 even when the filter circuit 2 is used.

[0034] Furthermore, in the lighting device 10 according to the first embodiment, the filter circuit 2 includes a resistor R1 connected in series between the zero-cross detection circuit 4 and the control circuit 1, and a capacitor C1 connected in parallel with the resistor R1, which makes it possible to remove harmonic components from the zero-cross detection signal S1.

[0035] Furthermore, in the lighting device 10 according to the first embodiment, the third time T3 is determined based on the time constant of the filter circuit 2. This makes it possible to improve the detection accuracy of the zero-crossing point ZP1.

[0036] Furthermore, in the lighting device 10 according to the first embodiment, the n+1th zero-cross point determination process is performed using the average value of the third times T3 calculated based on n third times T3, so that the third timing (zero-cross point ZP1) can be determined with high accuracy.

[0037] (Embodiment 2) A lighting device 10A according to the second embodiment will be described with reference to Fig. 3. Regarding the lighting device 10A according to the second embodiment, the same components as those of the lighting device 10 according to the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

[0038] The lighting device 10A according to the second embodiment differs from the lighting device 10 according to the first embodiment in that it includes a temperature sensor 5.

[0039] 3, the lighting device 10A according to the second embodiment includes a control circuit 1, a filter circuit 2, a rectifier circuit 3, a zero-cross detection circuit 4, and a plurality of resistors R2 and R3 (two in the illustrated example). The lighting device 10A according to the second embodiment further includes a temperature sensor 5.

[0040] Temperature sensor 5 detects the temperature in the space in which lighting device 10A is installed. That is, temperature sensor 5 detects the ambient temperature. Temperature sensor 5 is installed, for example, inside the housing of lighting device 10A, but may also be installed outside the housing.

[0041] The control circuit 1 determines the third time T3 based on the temperature detected by the temperature sensor 5. That is, the third time T3 is determined based on the temperature detected by the temperature sensor 5. As an example, as shown in Table 1, when the temperature detected by the temperature sensor 5 is 10°C, the third time T3 is 10 μs. When the temperature detected by the temperature sensor 5 is 210°C, the third time T3 is 12 μs. When the temperature detected by the temperature sensor 5 is 30°C, the third time T3 is 50 μs.

[0042] [Table 1]

[0043] As with the lighting device 10 according to the first embodiment, the lighting device 10A according to the second embodiment is also able to accurately detect the zero-crossing point ZP1 even when using the filter circuit 2. Furthermore, the lighting device 10A according to the second embodiment makes it possible to determine (change) the third time T3 depending on the temperature (ambient temperature) in the space in which the lighting device 10A is installed.

[0044] The various configurations described in the second embodiment can be adopted in appropriate combination with the various configurations (including modified examples) described in the first embodiment.

[0045] (Embodiment 3) A lighting device 10B according to the third embodiment will be described with reference to Fig. 4. Regarding the lighting device 10B according to the third embodiment, the same components as those of the lighting device 10 according to the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

[0046] The lighting device 10B according to the third embodiment differs from the lighting device 10 according to the first embodiment in that the zero-crossing detection signal S1 before being input to the filter circuit 2 is input to the control circuit 1.

[0047] As shown in FIG. 4, the lighting device 10B according to the third embodiment includes a control circuit 1, a filter circuit 2, a rectifier circuit 3, a zero-cross detection circuit 4, and a plurality of resistors R2 and R3 (two in the illustrated example).

[0048] In this embodiment, a first end of the resistor R1 of the filter circuit 2 is connected to the control circuit 1, and the zero-crossing detection signal S1 before being input to the filter circuit 2 is input to the control circuit 1. Hereinafter, the zero-crossing detection signal S1 before being input to the filter circuit 2 may be referred to as the "first zero-crossing detection signal S1," and the zero-crossing detection signal S1 after passing through the filter circuit 2 may be referred to as the "second zero-crossing detection signal S1."

[0049] In the zero-cross point determination process, the control circuit 1 compares the first zero-cross detection signal S1 with the second zero-cross detection signal S1. More specifically, in the zero-cross point determination process, the control circuit 1 determines, for example, the difference between the rising timing of the first zero-cross detection signal S1 and the timing at which the signal value of the second zero-cross detection signal S1 exceeds the threshold value th1 as a third time T3.

[0050] In the lighting device 10B according to the third embodiment, similar to the lighting device 10 according to the first embodiment, even when the filter circuit 2 is used, it is possible to accurately detect the zero-cross point ZP1.

[0051] The various configurations described in the third embodiment can be adopted in appropriate combination with the various configurations (including modified examples) described in the first and second embodiments.

[0052] (Embodiment 4) A lighting device 10C according to the fourth embodiment will be described with reference to Fig. 5. Regarding the lighting device 10C according to the fourth embodiment, the same components as those of the lighting device 10 according to the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

[0053] The lighting device 10C according to the fourth embodiment differs from the lighting device 10 according to the first embodiment in that the lighting device 10C includes two filter circuits 2.

[0054] 5, a lighting device 10C according to the fourth embodiment includes a control circuit 1, two filter circuits 2, a rectifier circuit 3, a zero-crossing detection circuit 4, and a plurality of resistors R2 and R3 (two in the illustrated example). Hereinafter, one of the two filter circuits 2 may be referred to as a "first filter circuit 2," and the other filter circuit 2 may be referred to as a "second filter circuit 2."

[0055] As in the first embodiment, the first filter circuit 2 is connected between the zero-crossing detection circuit 4 and the control circuit 1. The second filter circuit 2 is connected directly to the control circuit 1 (see FIG. 5).

[0056] The control circuit 1 outputs a signal identical to the zero-crossing detection signal S1 output from the zero-crossing detection circuit 4 to the second filter circuit 2. Then, the signal that has passed through the second filter circuit 2 is input to the control circuit 1. That is, with this configuration, a signal like the zero-crossing detection signal S1 shown in FIG. 2 is input to the control circuit 1. Therefore, the control circuit 1 can set the third timing calculated based on the signal as the zero-crossing point ZP1.

[0057] In the lighting device 10 according to the fourth embodiment, similarly to the first embodiment, even when the filter circuit 2 is used, it is possible to accurately detect the zero-cross point ZP1.

[0058] The various configurations described in the fourth embodiment can be adopted in appropriate combination with the various configurations (including modified examples) described in the first to third embodiments.

[0059] (Aspect) The present specification discloses the following aspects.

[0060] A lighting device (10; 10A; 10B; 10C) according to a first aspect includes a zero-crossing detection circuit (4), a control circuit (1), and a filter circuit (2). The zero-crossing detection circuit (4) detects a zero-crossing point (ZP1) of an AC voltage (V1) supplied from an AC power source (AC1). The control circuit (1) receives a zero-crossing detection signal (S1) as a result of detection by the zero-crossing detection circuit (4). The filter circuit (2) is connected between the zero-crossing detection circuit (4) and the control circuit (1). The control circuit (1) executes a zero-crossing point determination process to determine a third timing between the first timing and the second timing as the zero-crossing point (ZP1), where the first time (T1) is the time from the first change point to the second change point, and the second time (T2) is half the time of the first time (T1). At the first change point, the signal value of the zero-crossing detection signal (S1) changes to exceed a threshold value (th1). At the second change point, the signal value changes to fall below the threshold value (th1). The first timing corresponds to the first change point. The second timing is the first timing plus a second time (T2).

[0061] According to this embodiment, even when the filter circuit (2) is used, it is possible to accurately detect the zero cross point (ZP1).

[0062] In the lighting device (10; 10A; 10B; 10C) according to the second aspect, when the time from the second timing to the third timing in the first aspect is defined as the third time (T3), the third time (T3) is greater than 0 and less than the second time (T2).

[0063] According to this embodiment, even when the filter circuit (2) is used, it is possible to accurately detect the zero cross point (ZP1).

[0064] In the lighting device (10; 10A; 10B; 10C) according to the third aspect, in the second aspect, the filter circuit (2) has a resistor (R1) and a capacitor (C1). The resistor (R1) is connected in series between the zero-cross detection circuit (4) and the control circuit (1). The capacitor (C1) is connected in parallel with the resistor (R1).

[0065] According to this embodiment, it is possible to remove harmonic components from the zero-cross detection signal (S1).

[0066] In the lighting device (10; 10A; 10B; 10C) according to the fourth aspect, in the third aspect, the third time (T3) is determined based on the time constant of the filter circuit (2).

[0067] According to this embodiment, it is possible to determine the third time (T3) based on the time constant of the filter circuit (2).

[0068] The lighting device (10A) according to a fifth aspect is any one of the second to fourth aspects, and further includes a temperature sensor (5) that detects an ambient temperature. The third time (T3) is determined based on the temperature detected by the temperature sensor (5).

[0069] According to this embodiment, it is possible to determine the third time (T3) based on the ambient temperature.

[0070] A lighting device (10; 10A; 10B; 10C) according to a sixth aspect is any one of the second to fifth aspects, in which the control circuit (1) executes the zero-crossing point determination process n times (n is an integer equal to or greater than 2). The control circuit (1) calculates an average value of the second time (T2) based on the n first times (T1). In the (n+1)th zero-crossing point determination process, the control circuit (1) determines a third timing using the average value of the second times (T2) and a third time (T3).

[0071] According to this aspect, it is possible to determine the third timing with high accuracy.

[0072] The configurations according to the second to sixth aspects are not essential for the lighting device (10; 10A; 10B; 10C) and can be omitted as appropriate. [Explanation of symbols]

[0073] 1 Control circuit 2. Filter circuit 4 Zero-cross detection circuit 5 Temperature Sensor 10,10A,10B,10C lighting device AC1 AC power supply C1 capacitor R1 resistor S1 Zero cross detection signal T1 1st Hour T2 2nd Hour T3 Third Hour th1 threshold V1 AC voltage ZP1 Zero cross point

Claims

1. a zero-cross detection circuit that detects a zero-cross point of an AC voltage supplied from an AC power supply; a control circuit to which a zero-cross detection signal, which is a detection result of the zero-cross detection circuit, is input; a filter circuit connected between the zero-crossing detection circuit and the control circuit, the control circuit executes a zero-cross point determination process in which, when a first time is defined as a time from a first change point at which the signal value of the zero-cross detection signal changes to exceed a threshold value to a second change point at which the signal value changes to fall below the threshold value, and a second time is defined as half of the first time, the control circuit determines a third timing between a first timing corresponding to the first change point and a second timing obtained by adding the second time to the first timing as the zero-cross point. Lighting device.

2. When a time from the second timing to the third timing is defined as a third time, the third time is greater than 0 and smaller than the second time. The lighting device according to claim 1 .

3. The filter circuit comprises: a resistor connected in series between the zero-crossing detection circuit and the control circuit; a capacitor connected in parallel with the resistor, The lighting device according to claim 2 .

4. the third time period is determined based on a time constant of the filter circuit. The lighting device according to claim 3 .

5. Further provided is a temperature sensor for detecting an ambient temperature; the third time period is determined based on the temperature detected by the temperature sensor. The lighting device according to any one of claims 2 to 4.

6. The control circuit Executing the zero-crossing point determination process n times (n is an integer equal to or greater than 2); Calculating an average value of the second time based on n number of the first times; In the (n+1)th zero-crossing point determination process, the third timing is determined using the average value of the second times and the third time. The lighting device according to any one of claims 2 to 4.

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