Lighting circuit and lighting device

Abstract

To selectively drive a first light source and a second light source to be turned on with a simple configuration.SOLUTION: A lighting circuit supplies a drive current to a first light source and a second light source. The lighting circuit includes a lighting drive circuit connected to a first power supply line and a second power supply line and performing a first lighting drive for supplying a drive current to the first light source according to a voltage level of the first power supply line, and performing a second lighting drive for supplying a drive current to the second light source according to a voltage level of the second power supply line; a detection circuit for detecting lighting of the first light source on the basis of the voltage of the first power supply line; and a cutoff circuit having a switch connected to the second power supply line and opening the switch to cut off the second power supply line when the detection circuit detects lighting of the first light source.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a lighting circuit and a lighting device. [Background technology]

[0002] Conventionally, lighting circuits that selectively perform lighting drive for a plurality of light sources have been known. For example, a vehicle lamp includes various lamps as light sources, such as headlights, daytime running lamps, clearance lamps, turn signal lamps, tail lamps, and stop lamps, and a lighting circuit. The lighting circuit selectively performs lighting drive for the daytime running lamps and lighting drive for the clearance lamps, for example. In the conventional lighting circuit, a cutoff circuit is provided between an output line that supplies a drive current from a floodlight drive circuit to the daytime running lamps, and the cutoff circuit is configured to cut off the output line to turn off the daytime running lamps when the clearance lamps are turned on (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-198173 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional lighting circuit, as described above, the cutoff circuit is provided in the output line between the lighting drive circuit and the light source, so there is a problem that it is easily affected by the circuit configuration between the daytime running lamp and the lighting drive circuit. Note that this problem is not limited to daytime running lamps and clearance lamps, but is also a common problem with lighting circuits that selectively drive the lighting of multiple other types of light sources.

[0005] This specification discloses a technique that can solve the above-mentioned problems. [Means for solving the problem]

[0006] The technology disclosed in this specification can be realized, for example, in the following forms.

[0007] (1) The lighting circuit disclosed in this specification is a lighting circuit that supplies a drive current to a first light source and a second light source. The lighting circuit includes a lighting drive circuit that is connected to a first power supply line and performs a first lighting drive that supplies a drive current to the first light source according to a voltage level of the first power supply line, and a second lighting drive that is connected to a second power supply line and supplies a drive current to the second light source according to a voltage level of the second power supply line, a detection circuit that detects lighting of the first light source based on the voltage of the first power supply line, and a cutoff circuit that has a switch connected to the second power supply line and opens the switch to cut off the second power supply line when the detection circuit detects lighting of the first light source.

[0008] In this lighting circuit, a cutoff circuit (switch) for disabling the second lighting drive for the second light source is provided in a power supply line between an external device and the lighting drive circuit, not in an output line (current supply line) between the lighting drive circuit and the light source. Therefore, according to this lighting circuit, the first light source and the second light source can be selectively driven to light with a simple configuration that is less affected by the circuit configuration between the second light source and the lighting drive circuit, compared to a configuration in which a cutoff circuit is provided in the output line between the lighting drive circuit and the light source.

[0009] (2) In the above lighting circuit, the lighting drive circuit may have a reverse connection protection diode electrically connected to the second power supply line, and a reverse connection protection FET may be electrically connected to the second power supply line in a stage preceding the detection circuit and the cutoff circuit. When an external device is reverse-connected to the second power supply line, it is necessary to protect the detection circuit and the cutoff circuit (switch) electrically connected to the second power supply line. In contrast, according to the present lighting circuit, it is possible to realize protection against reverse connection while suppressing a voltage capable of lighting the second light source from being supplied to the lighting drive circuit due to a voltage drop caused by a diode, as compared to a configuration in which a reverse connection protection diode is also connected in a stage preceding the switch and the detection circuit.

[0010] (3) In the above lighting circuit, a negative surge protection diode may be electrically connected to the second power supply line in a stage preceding the detection circuit and the cutoff circuit. In a configuration in which a reverse connection protection FET is electrically connected to the second power supply line, a negative surge may pass through the reverse connection protection FET, making it impossible to protect the detection circuit and the cutoff circuit. In contrast, according to this lighting circuit, even if a negative surge passes through the reverse connection protection FET, the detection circuit and the cutoff circuit can be protected by the negative surge protection diode.

[0011] (4) In the above lighting circuit, the lighting drive circuit may have a positive surge protection capacitor electrically connected to the second power supply line, and a positive surge protection Zener diode may be electrically connected to the second power supply line in a stage upstream of the detection circuit and the cutoff circuit. When a positive surge occurs in the second power supply line, it is necessary to protect the detection circuit and the cutoff circuit (switch) electrically connected to the second power supply line. In contrast, according to this lighting circuit, it is possible to reduce the inrush current flowing through the second power supply line, compared to a configuration in which a positive surge protection capacitor is connected in a stage upstream of the switch and the detection circuit.

[0012] (5) A lighting device may be configured to include the first light source, the second light source, and the lighting circuit. With this configuration, the first light source and the second light source can be selectively driven to light by a simple configuration that is not easily affected by the circuit configuration of the second light source and the lighting drive circuit.

[0013] (6) In the above lighting device, the lighting device may be mounted on a vehicle, the light emitting surface of the first light source and the light emitting surface of the second light source may be disposed adjacent to each other or may be shared, the first light source may be a light source for a turn signal lamp, and the second light source may be a light source for a daytime running lamp. With this configuration, the turn signal lamp and the daytime running lamp can be selectively driven to light with a simple configuration that is not easily affected by the circuit configuration of the daytime running lamp and the lighting drive circuit.

[0014] The technology disclosed in this specification can be realized in various forms, for example, in the form of a lighting circuit, a lamp device including the lighting circuit and a plurality of light sources, etc. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a vehicle lamp according to an embodiment; [Diagram 2] FIG. 1 is an explanatory diagram showing the light-emitting surface of a light source unit. [Diagram 3] A timing chart showing the on / off transitions of turn signal lamps and daytime running lamps [Figure 4] An explanatory diagram showing the circuit configuration of a lighting circuit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] A. Embodiment: A-1. Configuration of the vehicle lamp 10: Fig. 1 is a block diagram showing a schematic configuration of a vehicle lamp 10 according to the present embodiment. As shown in Fig. 1, the vehicle lamp 10 is a lamp mounted on a vehicle, and includes a light source unit 21 and a lighting circuit 40. The vehicle lamp 10 is an example of a lighting device.

[0017] The light source unit 21 includes a turn signal lamp 20 and a daytime running lamp 30. The turn signal lamp 20 functions as a direction indicator and lights up in various patterns to inform the driver of a left turn, a right turn, a lane change, or the like of a vehicle. Specifically, the turn signal lamp 20 has a configuration in which, for example, a plurality of first light-emitting elements 22 (LEDs, etc.) are connected in series. The daytime running lamp 30 functions as a daytime light and, in principle, is always turned on while the vehicle is running. Specifically, the daytime running lamp 30 has a configuration in which, for example, a plurality of second light-emitting elements 32 (LEDs, etc.) are connected in series. The turn signal lamp 20 is an example of a first light source, and the daytime running lamp 30 is an example of a second light source.

[0018] Fig. 2 is an explanatory diagram showing a light emitting surface of the light source unit 21. Fig. 2(A) illustrates a common light emitting surface 24 of the light source unit 21. The common light emitting surface 24 is the light emitting surface of the turn signal lamps 20 and also the light emitting surface of the daytime running lamps 30. Specifically, behind the common light emitting surface 24, a plurality of first light emitting elements 22 and a plurality of second light emitting elements 32 are arranged side by side along the extension direction of the common light emitting surface 24.

[0019] FIG. 2B illustrates a configuration in which the light-emitting surface 24A of the turn signal lamp 20 and the light-emitting surface 24B of the daytime running lamp 30 are disposed in close proximity to each other. Behind the light-emitting surface 24A, a plurality of first light-emitting elements 22 are disposed in a line along the extension direction of the light-emitting surface 24A. Behind the light-emitting surface 24B, a plurality of second light-emitting elements 32 are disposed in a line along the extension direction of the light-emitting surface 24B. In this configuration in which the light-emitting surface of the turn signal lamp 20 and the light-emitting surface of the daytime running lamp 30 are common or disposed in close proximity to each other, it may be required, for example, by laws and regulations to turn off the daytime running lamp 30 during the turn signal lamp 20 is turned on.

[0020] The lighting circuit 40 is a circuit that supplies drive current to the turn signal lamps 20 and the daytime running lamps 30. The lighting circuit 40 includes a lighting drive circuit 50 and an arbitration circuit 60. In this embodiment, the lighting drive circuit 50 and the arbitration circuit 60 are formed on different substrates and are electrically connected to each other via wiring. Therefore, by electrically connecting the arbitration circuit 60 between the lighting circuit 40 and the ECU 80 described below, the daytime running lamps 30 can be turned off during the lighting period of the turn signal lamps 20.

[0021] The lighting drive circuit 50 has an input terminal P7 electrically connected to a TURN power supply line Lt connected to an ECU (Electronic Control Unit) 80 for a vehicle. The ECU 80 supplies a lighting instruction signal St for the turn signal lamp 20 to the TURN power supply line Lt. The lighting instruction signal St for the turn signal lamp 20 has a TURN voltage Vt for lighting the turn signal lamp 20. In this embodiment, the lighting instruction signal St for the turn signal lamp 20 is a pulse signal in which the TURN voltage Vt changes in a pulse shape (see FIG. 3 described later). The lighting drive circuit 50 is electrically connected to the turn signal lamp 20 (first light-emitting element 22). When the TURN voltage Vt is applied to the TURN power supply line Lt, the lighting drive circuit 50 supplies a drive current to the turn signal lamp 20 to light it.

[0022] Furthermore, the lighting drive circuit 50 has an input terminal P8 electrically connected to a DRL power supply line Ld connected to the ECU 80. The ECU 80 supplies a lighting instruction signal Sd for the daytime running lamps 30 to the DRL power supply line Ld. The lighting instruction signal Sd for the daytime running lamps 30 has a DRL voltage Vd for turning on the daytime running lamps 30. In this embodiment, the lighting instruction signal Sd for the daytime running lamps 30 is a signal in which the DRL voltage Vd is at a substantially constant level (see FIG. 3 described later). The lighting drive circuit 50 is electrically connected to the daytime running lamps 30 (the second light-emitting element 32). When the DRL voltage Vd is supplied to the DRL power supply line Ld, the lighting drive circuit 50 supplies a drive current to the daytime running lamps 30 to turn them on.

[0023] The lighting drive circuit 50 has an input terminal P9 electrically connected to a GND line Lg connected to the ECU 80. In this embodiment, the ECU 80 does not perform control to turn off the daytime running lamps 30 during the lighting period of the turn signal lamps 20.

[0024] The arbitration circuit 60 is electrically connected between the ECU 80 and the lighting drive circuit 50. Specifically, the TURN power line Lt is formed on the substrate of the arbitration circuit 60 from the input terminal P1, is led to the outside of the arbitration circuit 60 via the output terminal P4, and is electrically connected to the input terminal P7 of the lighting drive circuit 50. The DRL power line Ld is formed on the substrate of the arbitration circuit 60 from the input terminal P2, is led to the outside of the arbitration circuit 60 via the output terminal P5, and is electrically connected to the input terminal P8 of the lighting drive circuit 50. The GND line Lg is formed on the substrate of the arbitration circuit 60 from the input terminal P3, is led to the outside of the arbitration circuit 60 via the output terminal P6, and is electrically connected to the input terminal P9 of the lighting drive circuit 50.

[0025] The lighting circuit 40 includes a switch 62, an on / off control circuit 64, a detection circuit 66, a timer circuit 68, and a constant voltage circuit 70. The switch 62 and the on / off control circuit 64 are an example of a cutoff circuit.

[0026] The switch 62 is connected to the DRL power supply line Ld. When the switch 62 is in a closed state, a lighting instruction signal Sd from the ECU 80 can be supplied to the lighting drive circuit 50 via the DRL power supply line Ld. When the switch 62 is in an open state, the DRL power supply line Ld is interrupted, and therefore, the lighting instruction signal Sd from the ECU 80 is prohibited from being supplied to the lighting drive circuit 50. In other words, when the switch 62 is in an open state, the daytime running lamps 30 are turned off regardless of the presence or absence of the lighting instruction signal Sd from the ECU 80.

[0027] The detection circuit 66 detects the lighting of the turn signal lamp 20 based on the output of the TURN voltage Vt of the TURN power supply line Lt. That is, the detection circuit 66 detects the presence or absence of the output of the lighting instruction signal St from the ECU 80. When the detection circuit 66 detects the lighting instruction signal St, a detection signal indicating the detection of the lighting instruction signal St is provided to the on-off control circuit 64 via the timer circuit 68. When the on-off control circuit 64 does not receive the detection signal, it closes the switch 62, and when it receives the detection signal, it opens the switch 62. As a result, the daytime running lamp 30 is turned off during the lighting period of the turn signal lamp 20. In this embodiment, when the lighting instruction signal St is received from the ECU 80, the turn signal lamp 20 is turned on instantaneously (for example, several ms or more, several tens of ms or less) shorter than a monitoring time Tm described later.

[0028] The timer circuit 68 starts counting a monitoring time (e.g., 350 ms or more, 400 ms) from the time when the detection signal is no longer received from the detection circuit 66. The timer circuit 68 outputs an allowance instruction to the on / off control circuit 64 to allow the switch 62 to be changed from an open state to a closed state, on the condition that the state where the detection signal is not received continues for a monitoring time tm (longer than the off time of the TURN voltage Vt). After changing the switch 62 to an open state, the on / off control circuit 64 maintains the switch 62 in the open state until it receives an allowance instruction from the on / off control circuit 64, and when it receives the allowance instruction, it returns the switch 62 to a closed state. In this way, the daytime running lamps 30 are allowed to be turned on after the turn signal lamps 20 are surely turned off, so that simultaneous lighting of the turn signal lamps 20 and the daytime running lamps 30 can be effectively avoided.

[0029] The constant voltage circuit 70 is connected between the DRL power supply line Ld and the GND line Lg, and generates a constant voltage to be provided to the timer circuit 68. The timer circuit 68 counts a time corresponding to the constant voltage provided from the constant voltage circuit 70 as a monitoring time. The arbitration circuit 60 includes an input filter 72 and an output filter 76 for static electricity countermeasures for the TURN power supply line Lt. The arbitration circuit 60 also includes an input filter 74 and an output filter 78 for static electricity countermeasures for the DRL power supply line Ld.

[0030] FIG. 3 is a time chart showing the transition of the on / off state of the turn signal lamps 20 and the daytime running lamps 30. As shown in FIG. 3, in the period before time t0, the turn signal lamps 20 ("TURN" in FIG. 3) and the daytime running lamps 30 ("DRL" in FIG. 3) are both turned off ("OFF" in FIG. 3) because the turn-on instruction signal St and the turn-on instruction signal Sd are not output from the ECU 80. When the turn-on instruction signal Sd is output from the ECU 80 at time t0, the timer circuit 68 in the arbitration circuit 60 functions, and turns on the daytime running lamps 30 on ("ON" in FIG. 3, see time t1) on the condition that a state in which a detection signal indicating that the turn signal lamps 20 have been turned on has continued for a monitoring time tm. In this way, in this embodiment, even when the daytime running lamps 30 are turned on alone, simultaneous lighting of the turn signal lamps 20 and the daytime running lamps 30 is reliably avoided.

[0031] Next, when the lighting instruction signal St is output from the ECU 80 while the daytime running lamps 30 are on, the switch 62 in the arbitration circuit 60 is opened, and the daytime running lamps 30 are turned off and the turn signal lamps 20 are turned on despite the lighting instruction signal Sd being output from the ECU 80 (see time t2). In this embodiment, since the lighting instruction signal St is a pulse signal, the turn signal lamps 20 are pulse-lit. When the lighting instruction signal St is no longer output from the ECU 80, the turn signal lamps 20 are turned off (see time t3). However, at this point, the daytime running lamps 30 are not turned on. As described above, the timer circuit 68 in the arbitration circuit 60 functions, and the daytime running lamps 30 are turned on under the condition that a state in which a detection signal indicating that the turn signal lamps 20 have been turned on has continued for the monitoring time tm (see time t4).

[0032] A-2. Configuration for protecting the lighting circuit 40: FIG. 4 is an explanatory diagram showing the circuit configuration of the lighting circuit 40. In FIG. 4, the GND line Lg is omitted. As shown in FIG. 4, in the lighting drive circuit 50, a diode 56 and a positive surge protection capacitor 58 are electrically connected to the connection line between the input terminal P7 and the turn signal lamp 20. The diode 56 plays a role in protecting the internal circuit of the lighting drive circuit 50 when an external device (such as the ECU 80) is electrically reverse-connected to the TURN power supply line Lt. The positive surge protection capacitor 58 plays a role in absorbing surges and removing conducted noise with respect to the TURN power supply line Lt. In addition, in the lighting drive circuit 50, a diode 52 and a positive surge protection capacitor 54 are electrically connected to the connection line between the input terminal P8 and the daytime running lamp 30. The diode 52 plays a role in protecting the internal circuit of the lighting drive circuit 50 when an external device (such as the ECU 80) is electrically reverse-connected to the DRL power supply line Ld. The positive surge protection capacitor 54 serves to absorb surges and remove conducted noise for the DRL power line Ld.

[0033] The switch 62 has an interrupter FET (field effect transistor) 62a. A Zener diode 62d, a capacitor 62c, and a resistor element 62d are connected in parallel between the drain and source of the interrupter FET 62a. The on / off control circuit 64 has a transistor 64a, and controls the on / off of the interrupter FET 62a of the switch 62 based on the presence or absence of a detection signal from a timer circuit 68.

[0034] A-2-1. Configuration for reverse connection protection: In the arbitration circuit 60, a reverse connection protection diode 69 is electrically connected between the input terminal P1 and the timer circuit 68. The reverse connection protection diode 69 plays a role in protecting internal circuits such as the detection circuit 66 when an external device (such as the ECU 80) is electrically reverse-connected to the TURN power line Lt. Meanwhile, a reverse connection protection FET 92 is electrically connected between the input terminal P2 and the switch 62. The gate of the reverse connection protection FET 92 is connected to ground via a resistor element 94. A capacitor 96 and a Zener diode 98 are connected in parallel between the gate and source of the reverse connection protection FET 92. In a normal connection state in which the positive terminal of a power supply (not shown) is electrically connected to the input terminal P1 and the input terminal P3 is electrically connected to the negative terminal of the power supply, the reverse connection protection FET 92 is turned on, and a current flows normally through the drain-source path of the reverse connection protection FET 92. On the other hand, in a reverse connection state in which the positive terminal of the power supply is electrically connected to the input terminal P3 and the input terminal P1 is electrically connected to the negative terminal of the power supply, the body diode of the reverse connection protection FET 92 blocks the drain-source path of the reverse connection protection FET 92, and the reverse connection protection FET 92 does not turn on but maintains the off state. However, the voltage drop due to the on resistance of the reverse connection protection FET 92 is extremely small compared to the voltage drop of the reverse connection protection diode 69.

[0035] If a reverse connection protection diode were connected instead of the reverse connection protection FET 92, the voltage supplied to the daytime running lamp 30 (second light-emitting element 32) would be lowered due to a voltage drop corresponding to the combined resistance of the voltage drop of the reverse connection protection diode and the voltage drop of the diode 52, and there is a risk that a voltage sufficient to light the daytime running lamp 30 would not be supplied. In contrast, in this embodiment, the voltage drop due to the on-resistance of the reverse connection protection FET 92 is relatively small, so reverse connection protection can be achieved while suppressing the occurrence of lighting failures of the daytime running lamp 30 due to a voltage drop due to the diode.

[0036] A-2-2. Configuration for negative surge protection: In the arbitration circuit 60, a negative surge protection diode 110 is further electrically connected between the input terminal P2 and the switch 62. Specifically, the negative surge protection diode 110 is connected between the DRL power supply line Ld and the constant voltage circuit 70. The anode of the negative surge protection diode 110 is electrically connected to the DRL power supply line Ld, and the cathode of the negative surge protection diode 110 is electrically connected to the constant voltage circuit 70.

[0037] Here, in a configuration in which the reverse connection protection FET 92 is electrically connected to the DRL power supply line Ld, a negative surge passes through the reverse connection protection FET 92 and is input to the subsequent circuits (constant voltage circuit 70, etc.), which may damage the semiconductor elements (transistors, etc.) that make up these circuits. In contrast, in this embodiment, even if a negative surge passes through the reverse connection protection FET, the negative surge protection diode 110 can protect the subsequent circuits (detection circuit 66, cutoff circuit, constant voltage circuit 70).

[0038] A-2-3. Configuration for positive surge protection: In the arbitration circuit 60, a positive surge protection Zener diode 100 is further electrically connected between the input terminal P2 and the switch 62. The cathode of the positive surge protection Zener diode 100 is electrically connected to the DRL power supply line Ld, and the anode of the positive surge protection Zener diode 100 is electrically connected to the ground.

[0039] Here, when a positive surge occurs in the DRL power supply line Ld, it is necessary to protect the switch 62 and the detection circuit 66 electrically connected to the DRL power supply line Ld. If a positive surge protection capacitor were connected instead of the positive surge protection Zener diode 100, an inrush current would flow through the DRL power supply line Ld, which could have adverse effects such as damage to the circuit electronic components (such as the switch 62) and failure of the vehicle system (such as the ECU 80 and the body control module). In contrast, according to this embodiment, the positive surge protection Zener diode 100 is connected in front of the switch 62, etc., so that the inrush current flowing through the DRL power supply line Ld can be reduced.

[0040] A-3. Advantages of this embodiment: As described above, in the lighting circuit 40 of the vehicle lamp 10 according to this embodiment, the interrupter circuit (switch 62) for disabling the lighting drive for the daytime running lamps 30 is provided in the power supply line between the ECU 80 and the lighting drive circuit 50, rather than in the output line between the lighting drive circuit 50 and the light source unit 21 (daytime running lamps 30). Therefore, according to this embodiment, the turn signal lamps 20 and the daytime running lamps 30 can be selectively driven to light with a simple configuration that is less affected by the circuit configuration between the daytime running lamps 30 and the lighting drive circuit 50, compared to a configuration in which a interrupter circuit is provided in the output line, for example.

[0041] B. Variations: The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0042] The configuration of the vehicle lamp 10 in the above embodiment is merely an example, and various modifications are possible. For example, in the above embodiment, the vehicle lamp 10 is exemplified as a lighting device, but the lighting device may be a device disposed on a moving body other than a vehicle or a fixed device. In addition, in the above embodiment, the turn signal lamp 20 and the daytime running lamp 30 are exemplified as the first light source and the second light source, but the first light source and the second light source are not limited to this, and other types of light sources such as headlights, clearance lamps, tail lamps, and stop lamps may be used. In addition, the light source is not limited to an LED, and may be configured to include other light emitting elements such as a halogen lamp.

[0043] In the above embodiment, the lighting drive circuit 50 and the arbitration circuit 60 are formed on different substrates, but they may be formed on a common substrate. In the above embodiment, a reverse connection protection diode may be connected instead of the reverse connection protection FET 92. In addition, in the above embodiment, at least one of the positive surge protection Zener diode 100 and the negative surge protection diode 110 may not be provided. [Explanation of symbols]

[0044] 10: Vehicle lamp 20: Turn signal lamp 21: Light source unit 22: First light-emitting element 24: Common light-emitting surface 24A, 24B: Light-emitting surface 30: Daytime running lamp 32: Second light-emitting element 40: Lighting circuit 50: Lighting drive circuit 54: Positive surge protection capacitor 58: Positive surge protection capacitor 60: Arbitration circuit 62: Switch 62a: Shutdown FET 62a: Shutdown FET (field-effect transistor) 62c: Capacitor 62d: Zener diode 64: On-off control circuit 64a: Transistor 66: Detection circuit 68: Timer circuit 69: Reverse connection protection diode 70: Constant voltage circuit 80: ECU 92: Reverse connection protection FET 100: Positive surge protection Zener diode 110: Negative surge protection diode Ld: DRL power line Lg: GND line Lt: TURN power line

Claims

1. A lighting circuit that supplies a driving current to a first light source and a second light source, a lighting drive circuit that is connected to a first power supply line and performs a first lighting drive for supplying a drive current to the first light source in accordance with a voltage level of the first power supply line, and a second lighting drive that is connected to a second power supply line and performs a second lighting drive for supplying a drive current to the second light source in accordance with a voltage level of the second power supply line; a detection circuit that detects lighting of the first light source based on a voltage of the first power supply line; a cut-off circuit having a switch connected to the second power supply line, and opening the switch to cut off the second power supply line when the detection circuit detects that the first light source is turned on.

2. 2. The lighting circuit according to claim 1, the lighting drive circuit has a reverse connection protection diode electrically connected to the second power supply line, a reverse connection protection FET is electrically connected to the second power supply line in a stage upstream of the detection circuit and the cutoff circuit.

3. 3. The lighting circuit according to claim 2, a negative surge protection diode is electrically connected to the second power supply line in a stage upstream of the detection circuit and the cutoff circuit;

4. 2. The lighting circuit according to claim 1, the lighting drive circuit has a positive surge protection capacitor electrically connected to the second power supply line, a Zener diode for positive surge protection is electrically connected to the second power supply line in a stage upstream of the detection circuit and the cutoff circuit;

5. The first light source; the second light source; A lighting device comprising: a lighting circuit according to any one of claims 1 to 4.

6. 6. The lighting device according to claim 5, The lighting device is mounted on a vehicle, The light emitting surface of the first light source and the light emitting surface of the second light source are disposed adjacent to each other or are shared, The first light source is a light source serving as a turn signal lamp, A lighting device, wherein the second light source is a light source serving as a daytime running lamp.

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