Lighting circuit and vehicle lamp

Abstract

To provide a turn-on circuit that reliably stops operating at occurrence of abnormality.SOLUTION: Provided is a turn-on circuit that is applied to a lighting fixture for vehicles. The turn-on circuit comprises: a power supply line with which a source voltage is supplied in a first period, out of a prescribed period including the first period and a second period, and the supply of the source voltage is halted in the second period; a regulator for supplying a drive current to a light source on the basis of the source voltage of the power supply line; a detection circuit for detecting the presence of abnormality in the light source; a signal output circuit that operates on the basis of the source voltage of the power supply line and outputs a signal that corresponds to the detection result of the detection circuit; and a control circuit for causing the operation of the regulator to stop when the signal that indicates the presence of abnormality in the light source is outputted. When the detection result that indicates the presence of abnormality in the light source is inputted in the first period, the signal output circuit holds the signal that indicates the presence of abnormality in the light source regardless of whether or not the source voltage is supplied to the power supply line.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a lighting circuit and a vehicle lamp. [Background technology]

[0002] A lighting circuit used in a vehicle turn signal lamp (a type of vehicle lamp) includes a regulator that generates a drive current based on a voltage (hereinafter, "turn voltage") that includes a high level period and a low level period in a predetermined cycle, and supplies the drive current to a light source to light (blink) the light source. In addition, in Patent Document 1, a holding circuit is provided that holds a signal (logical level) indicating an abnormality when an abnormality occurs and stops the operation of the regulator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-113038 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional holding circuit, even if a signal indicating an abnormality is held when an abnormality is detected, there is a risk that the held state will be released during the low level period, in which case the lighting circuit may operate again after switching from the low level period to the high level period.

[0005] An object of the present invention is to provide a lighting circuit that can reliably stop operation when an abnormality occurs. [Means for solving the problem]

[0006] The main invention for achieving the above-mentioned object is a lighting circuit applied to a vehicle lamp, comprising: a power supply line to which a power supply voltage is supplied during a predetermined cycle including a first period and a second period, and the supply of the power supply voltage is stopped during the second period; a regulator that supplies a drive current to a light source based on the power supply voltage of the power supply line; a detection circuit that detects whether or not there is an abnormality in the light source; a signal output circuit that operates based on the power supply voltage of the power supply line and outputs a signal according to the detection result of the detection circuit; and a control circuit that stops the operation of the regulator when the signal indicating that there is an abnormality in the light source is output, wherein when the detection result indicating that there is an abnormality in the light source during the first period is input, the signal output circuit holds the signal indicating that there is an abnormality in the light source regardless of whether the power supply voltage is supplied to the power supply line. Effect of the Invention

[0007] According to the present invention, it is possible to provide a lighting circuit that reliably stops operation when an abnormality occurs. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of the configuration of a vehicle lighting system including a turn signal lamp 10 according to an embodiment of the present invention. [Diagram 2] FIG. 4 is a diagram showing an example of the configuration of a disconnection detection circuit 45. [Diagram 3] FIG. 4 is a diagram showing an example of the configuration of a light-off circuit 47. [Figure 4] 4 is a diagram for explaining the operation of the lighting circuit 30. FIG. [Diagram 5] FIG. 13 is a diagram for explaining the effect of a diode D13. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] At least the following points will become apparent from the description of this specification and the accompanying drawings.

[0010] =====This embodiment===== <<System configuration>> Fig. 1 is a diagram showing an example of the configuration of a vehicle lighting system including a turn signal lamp 10 according to the present embodiment. The system shown in Fig. 1 includes a body control module (BCM) 110 provided on the vehicle side and a turn signal lamp 10 on the lamp side. The turn signal lamp 10 corresponds to a "vehicle lamp."

[0011] The BCM 110 is an electronic control unit (control device) that monitors and controls various electronic devices of the vehicle (wipers, door locks, lights, etc.). The BCM 110 of this embodiment includes a switch 111 and a disconnection detection circuit 115.

[0012] The switch 111 is an element for applying a power supply voltage Vbat (hereinafter, simply referred to as voltage Vbat) of a battery 101 for a vehicle to a power supply line L1 of the turn signal lamp 10. For example, a mechanical contact relay or a contactless relay using a semiconductor element is adopted as the switch 111. The voltage Vbat of the battery 101 is applied to one end of the switch 111, and the other end is connected to the power supply line L1. Therefore, when the switch 111 is turned on, the voltage Vbat is applied to the power supply line L1. In this embodiment, all the lines (inside and outside the lighting circuit 30) connected to the switch 111 are the power supply line L1. In particular, the inside of the lighting circuit 30 is also the power supply line L1. The power supply line L1 is a wiring that supplies a power supply voltage to a circuit inside the lighting circuit 30 via a terminal A (described later).

[0013] For example, when a driver of a vehicle operates a direction indicator (not shown) to turn on the turn signal lamp 10, a turn switch (not shown) is turned on and a turn signal ST (see FIG. 4) becomes a high level (hereinafter, H level). While the turn signal ST is at the H level, a control circuit (not shown) of the vehicle turns the switch 11 on and off.

[0014] As a result, a voltage (hereinafter also referred to as turn voltage Vt) that alternates between an H level period and a low level (hereinafter L level) period in a cycle Tx is generated and applied to the power supply line L1. In other words, the turn voltage Vt is a voltage for a cycle Tx that includes an H level period and an L level period, and the power supply line L1 is supplied with the voltage Vbat during the H level period and the supply of the voltage Vbat is stopped during the L level period. The period when the turn voltage Vt is at the H level corresponds to the "first period", and the period when it is at the L level corresponds to the "second period".

[0015] The disconnection detection circuit 115 is a circuit that detects whether or not there is a disconnection on the lamp side (specifically, a light-emitting element of the turn signal lamp 10 described later) based on a current (input current Iin) flowing through the power supply line L1. Note that in this embodiment, the disconnection detection circuit 115 is provided in the BCM 110, but is not limited to this and may be provided outside the BCM 110.

[0016] <<Configuration of turn signal lamp 10>> The turn signal lamp 10 is a vehicular direction indicator lamp (vehicular lamp) that sequentially lights up light-emitting elements of a light source based on a voltage Vbat of a vehicle battery 101. In this embodiment, a sequential type turn signal lamp is exemplified as the turn signal lamp 10, but the turn signal lamp is not limited to the sequential type and may be of another type.

[0017] The turn signal lamp 10 includes a first light source 21, a second light source 22, and a lighting circuit 30.

[0018] The first light source 21 is a light source including two light-emitting elements, namely, a light-emitting element D1 that is turned on first, and a light-emitting element D2 that is turned on following the light-emitting element D1. In this embodiment, light-emitting diodes (LEDs) are used for the light-emitting elements D1 and D2. However, the light-emitting elements D1 and D2 are not limited to LEDs, and may be other semiconductor light-emitting elements such as laser diodes (LDs) or organic EL elements, or halogen lamps (the same applies to the light-emitting elements D3 to D7 of the second light source 22 described later). The light-emitting elements D1 and D2 are connected in series between a terminal F and a terminal H, and the cathode of the light-emitting element D1 and the anode of the light-emitting element D2 are connected to a terminal G.

[0019] The second light source 22 is a light source including a plurality of (here, five) light-emitting elements D3 to D7 that are turned on after the light-emitting element D2 of the first light source 21 is turned on. The light-emitting elements D3 to D7 are connected in series between terminals D and E. Each of the first light source 21 and the second light source 22 corresponds to a "light source."

[0020] When the voltage Vbat is applied to the power line L1 (i.e., when the turn voltage Vt becomes H level), the lighting circuit 30 sequentially lights up the first light source 21 and the second light source 22 at a predetermined timing. The lighting circuit 30 will be described in detail later, but the lighting circuit 30 is a module in which a plurality of circuits for lighting the first light source 21 and the second light source 22 (light-emitting elements D1 to D7) and terminals A to H are attached to a board.

[0021] <<<Configuration of lighting circuit 30>>> As shown in FIG. 1, the lighting circuit 30 includes a VCC circuit 40, a linear regulator 41, a switching regulator 42, a first control circuit 43, a second control circuit 44, disconnection detection circuits 45 and 46, a light-out circuit 47, a timer circuit 48, a switch SW1, and terminals A to H.

[0022] The VCC circuit 40 is a power supply circuit that generates a voltage VCC (for example, 5 V) for operating each circuit of the lighting circuit 30 based on a turn voltage Vt (for example, a voltage Vbat of 12 V) of the power supply line L1.

[0023] The linear regulator 41 is a linear constant current circuit that generates a predetermined drive current I1 for driving the light emitting elements D1 and D2 of the first light source 21, which is a load. Specifically, when the switch 111 is turned on and the voltage Vbat is applied to the power supply line L1, the linear regulator 41 generates the predetermined drive current I1 based on the power supplied from the power supply line L1. The operation of the linear regulator 41 is controlled by the first control circuit 43.

[0024] The switching regulator 42 is a switching constant current circuit that generates a predetermined drive current I2 for driving the light emitting elements D3 to D7 of the second light source 22, which is a load. The switching regulator 42 is a constant current circuit that generates the drive current I2 based on the power supplied from the power supply line L1. The operation of the switching regulator 42 is controlled by a second control circuit 44.

[0025] In this embodiment, each of the linear regulator 41 and the switching regulator 42 corresponds to a "regulator", and the drive currents I1, I2 generated by each regulator correspond to a "drive current". Moreover, the linear regulator 41 that supplies the drive current I1 to the first light source 21 corresponds to a "first regulator", and the drive current I1 corresponds to a "first drive current". Moreover, the switching regulator 42 that supplies the drive current I2 to the second light source 22 corresponds to a "second regulator", and the drive current I2 corresponds to a "second drive current".

[0026] The first control circuit 43 outputs a signal S1 to the linear regulator 41 to generate the driving current I1, and controls the operation of the linear regulator 41.

[0027] In addition, the first control circuit 43 outputs a signal S13 indicating the detection result of the disconnection detection circuit 45 to the light-off circuit 47, and stops the operation of the linear regulator 41 when the signal S14 output from the light-off circuit 47 becomes an L level.

[0028] The second control circuit 44 outputs a signal S2 to the switching regulator 42 to control the operation of the switching regulator 42. The second control circuit 44 controls the operation of the switching regulator 42 based on a signal S4 input from a timer circuit 48. The signal S4 is a signal that indicates the operation timing of the switching regulator 42.

[0029] In addition, the second control circuit 44 outputs a signal S11 indicating the detection result of the disconnection detection circuit 46 to the light-off circuit 47, and stops the operation of the switching regulator 42 when the signal S12 output from the light-off circuit 47 becomes an L level.

[0030] Each of the first control circuit 43 and the second control circuit 44 corresponds to a "control circuit." Furthermore, the L-level signals S14 and S12 correspond to a "signal indicating that an abnormality exists in the light source" and a "signal indicating that an abnormality exists in either the first light source or the second light source."

[0031] The disconnection detection circuit 45 detects whether or not there is a disconnection in the light-emitting elements D1, D2 of the first light source 21 (i.e., whether or not there is an abnormality in the first light source 21) based on the output voltage of the linear regulator 41. Here, if there is a disconnection in either of the light-emitting elements D1, D2, the output voltage at the terminal F increases, and therefore the disconnection detection circuit 45 can detect the disconnection (details will be described later).

[0032] The disconnection detection circuit 45 of the present embodiment, for example, determines whether the output voltage of the linear regulator 41 is higher than a predetermined value V1, and detects that the first light source 21 has a disconnection when the output voltage becomes higher than the predetermined value V1.

[0033] Fig. 2 is a diagram showing an example of the configuration of the disconnection detection circuit 45. The disconnection detection circuit 45 shown in Fig. 2 has resistors R51 and R52 and a comparator 53. Note that the disconnection detection circuit 46 described later can also have a similar configuration.

[0034] The resistors R51 and R52 divide the output voltage Vout of the linear regulator 41, and are connected in series between the output line of the linear regulator 41 and the ground.

[0035] The comparator 53 has an inverting input terminal (negative terminal) to which a voltage Vdiv (a divided voltage of the output voltage Vout) at the connection point between the resistors 51 and 52 is applied, and a non-inverting input terminal (positive terminal) to which a voltage Vref is applied. In this embodiment, the voltage level of the voltage Vref and the resistance values ​​of the resistors 51 and 52 are determined so that the voltage Vdiv becomes higher than the voltage Vref when the output voltage Vout becomes higher than a predetermined voltage (here, a predetermined value V1).

[0036] The comparator 53 compares the voltage Vdiv with the voltage Vref, and outputs an L-level signal if the voltage Vdiv is higher than the voltage Vref. On the other hand, if the voltage Vdiv is lower than the voltage Vref, it outputs an H-level signal. That is, if there is no abnormality in the first light source 21 (disconnection of the light-emitting element), the output of the disconnection detection circuit 45 becomes an H-level, and if there is an abnormality in the first light source 21, the output of the disconnection detection circuit 45 becomes an L-level.

[0037] The disconnection detection circuit 46 detects whether or not there is a disconnection in the light emitting elements D3 to D7 of the second light source 22 (i.e., whether or not there is an abnormality in the second light source 22) based on the output voltage of the switching regulator 42. Specifically, like the disconnection detection circuit 45, the disconnection detection circuit 46 detects that there is a disconnection in the second light source 22 when the output voltage of the switching regulator 42 becomes higher than a predetermined value V2. In this case, too, if there is no abnormality in the second light source 22 (disconnection of the light emitting elements), the output of the disconnection detection circuit 46 becomes H level, and if there is an abnormality in the second light source 22, the output of the disconnection detection circuit 46 becomes L level. Each of the disconnection detection circuits 45 and 46 corresponds to a "detection circuit." Also, the disconnection detection circuit 45 corresponds to a "first detection circuit," and the disconnection detection circuit 46 corresponds to a "second detection circuit."

[0038] The timer circuit 48 is a circuit for executing the sequential lighting operation. The timer circuit 48 operates based on the voltage VCC and measures the time since the turn voltage Vt changed. The timer circuit 48 changes the level of the signal S3 output to the switch SW1 and changes the level of the signal S4 output to the second control circuit 44 at an appropriate timing.

[0039] The switch SW1 is an element for sequentially lighting the light-emitting elements D1 and D2 of the first light source 21, and is turned on when the signal S3 of the timer circuit 48 becomes H level and turned off when it becomes L level. Here, the switch SW1 is provided between the terminals G and H so that the switch SW1 and the light-emitting element D2 are connected in parallel. Therefore, when the switch SW1 is turned on, the drive current I1 is supplied only to the light-emitting element D1 out of the light-emitting elements D1 and D2, and when the switch SW1 is turned off, the drive current I1 is supplied to both the light-emitting elements D1 and D2.

[0040] <<Configuration of the Light-Off Circuit 47>> The extinguishing circuit 47 is a circuit that, when either of the disconnection detection circuits 45, 46 detects a disconnection, stops the operation of the linear regulator 41 and the switching regulator 42 in order to turn off the first light source 21 and the second light source 22. Here, "stopping the operation of the regulator" means, for example, that the regulator stops generating at least a drive current and sets to a state in which the input current Iin does not flow (for example, a standby state).

[0041] The light-off circuit 47 operates based on the voltage VCC, and outputs signals S12, S14 according to the detection results of the disconnection detection circuits 45, 46. The light-off circuit 47 corresponds to the "signal output circuit."

[0042] FIG. 3 is a diagram showing an example of the configuration of the light-off circuit 47. As shown in FIG. The light-off circuit 47 includes an NPN transistor Q1, a PNP transistor Q2, an NMOS transistor Q3, capacitors C1 to C3, diodes D11 to D14, resistors R1 to R8, and diodes 65 and 66.

[0043] An inverter 61 is formed by the PNP transistor Q2, the resistor R5, and the diode D14, and an inverter 62 is formed by the resistors R6, R7, and the NMOS transistor Q3.

[0044] The inverter 61 is a circuit that inverts and outputs the logical level of the node N2, which is the output of the inverter 62, and includes a PNP transistor Q2, a resistor R5, and a diode D14 that are connected in series to a supply line of a voltage VCC. For example, when the level of the node N2 of the inverter 62 is at the H level, the PNP transistor Q2 is turned off, and the node N1 on the cathode side of the diode D14 is at the L level. On the other hand, when the level of the node N2 is at the L level, the PNP transistor Q2 is turned on, and the node N1 is at the H level.

[0045] The inverter 62 is a circuit that inverts the logical level of the node N1 and outputs it, and includes an NMOS transistor Q3 and resistors R6 and R7 connected in series to a supply line of a voltage VCC. For example, when the level of the node N1 is H level, the NMOS transistor Q3 turns on. Therefore, the levels of the node N2 and the node N3 to which the NMOS transistor Q3 and the resistor R7 are connected both become L level. When the level of the node N1 is L level, the NMOS transistor Q3 turns off, and the levels of the nodes N2 and N3 both become H level.

[0046] In this embodiment, a node N1 which is the output of the inverter 61 is connected to the gate electrode of an NMOS transistor Q3 which is the input of the inverter 62. Also, a node N2 which is the output of the inverter 62 is connected to the base electrode of a PNP transistor Q2 which is the input of the inverter 61. Therefore, the inverters 61 and 62 operate as a circuit that holds a logic level.

[0047] In this embodiment, the inverters 61 and 62, and a capacitor C3 and a resistor R8 (described later) correspond to a “holding circuit.” The NMOS transistor Q3 corresponds to a “first transistor,” and the gate electrode of the NMOS transistor Q3 corresponds to a “control electrode.”

[0048] The capacitor C3 and the resistor R8 constitute a circuit (time constant circuit) provided for determining the period (time constant) during which the logic level is held by the inverters 61 and 62.

[0049] One end of the capacitor C3 is connected to the node N1 (in other words, the gate electrode of the NMOS transistor Q3), and the other end is grounded. Therefore, when the charging voltage of the capacitor C3 reaches a predetermined level (the threshold voltage of the NMOS transistor Q3), the state (on state, off state) of the NMOS transistor Q3 changes. The capacitor C3 corresponds to the "first capacitor."

[0050] The resistor R8 is connected in parallel to the capacitor C3. In this embodiment, the resistor R8 has a resistance value that prevents the charging voltage of the capacitor C3 from becoming lower than the threshold voltage of the NMOS transistor Q3 during the period when the turn voltage Vt is at the L level (the period when the voltage Vbat is not supplied: the period T2 described later). The resistor R8 corresponds to the "first resistor."

[0051] The emitter electrode of the NPN transistor Q1 is grounded, and the collector electrode is connected to a node N4 between the resistor R4 (and the diode D12) and the capacitor C2 via the resistor R3. The NPN transistor Q1 corresponds to a "second transistor", and the node N4 corresponds to a "node" to which the NPN transistor Q1 and the resistor R4 are connected.

[0052] The base electrode of the NPN transistor Q1 is connected to one end of a resistor R2, the other end of which is applied with a voltage VCC. The base electrode of the NPN transistor Q1 is also connected to one end of a resistor R1, the other end of which is applied with a signal S11, and to the anode of a diode D11, the cathode of which is applied with a signal S13. The base electrode of the NPN transistor Q1 is also connected to a capacitor C1 for smoothing the input signal (signals S11, S13).

[0053] Resistor R4, diode D12, and capacitor C2 are connected in series.

[0054] When the NPN transistor Q1 is turned off, the resistor R4 supplies a charging current to the capacitors C2 and C3 via the diode D12. This charges the capacitors C2 and C3. The resistor R4 corresponds to the "second resistor", and the circuit including the NPN transistor Q1 and the resistor R4 corresponds to the "charging circuit".

[0055] The diode D13 is an element (backflow prevention element) for preventing the charge stored in the capacitor C3 from being discharged and the held state from being released when the NPN transistor Q1 is turned on. The anode of the diode D13 is connected to the node N4, and the cathode is connected to the node N1 (in other words, the capacitor C3).

[0056] When an open circuit is detected and the voltage of the node N3 becomes L level, the diode 65 generates an L level signal S12 at the anode for causing the second control circuit 44 to stop the operation of the linear regulator 41.

[0057] When an open circuit is detected and the voltage of the node N3 becomes the L level, the diode 66 generates at its anode a signal S14 of the L level for causing the first control circuit 43 to stop the operation of the switching regulator .

[0058] <<<Operation of lighting circuit 30>>> 4 is a diagram for explaining the operation of the lighting circuit 30. Here, for example, when a direction indicator (not shown) for blinking the turn signal lamp 10 is operated, a turn switch (not shown) is turned on and the turn signal ST becomes an H level.

[0059] In this embodiment, the switch 111 is controlled so as to repeatedly turn on and off at a predetermined period Tx (e.g., 800 ms) during a period Tton when the turn signal ST is at H level. It is assumed that each of the periods during which the switch 111 is on and off during the period Tx is half the period Tx (400 ms). During the period T1 when the switch 111 is on, the voltage Vbat is supplied to the power supply line L1, and during the period T2 when the switch 111 is off, the supply of the power supply voltage Vbat is stopped.

[0060] Furthermore, the first control circuit 43 and the second control circuit 44 control various circuits and elements so that the number of light-emitting elements to be turned on increases from "1", "2", to "7" while the switch 111 is on. In this embodiment, the period for turning on the first light source 21 and the second light source 22 within the period T1 is set to a period Ta (which may be within 200 ms, for example, 150 ms), and the period during which the first light source 21 and the second light source 22 are turned on is set to a period Tb (for example, 250 ms). Note that, since it is assumed here that none of the light-emitting elements D1 to D7 are disconnected, the light-off circuit 47 holds an H-level signal.

[0061] First, at time t0, when a direction indicator (not shown) for blinking the turn signal lamp 10 is operated (the turn signal ST becomes H level), the switch 111 is controlled to be turned on. As a result, the turn voltage Vt becomes H level, and the voltage Vbat of the battery 101 is supplied to the power supply line L1. The first control circuit 43 operates the linear regulator 41.

[0062] Furthermore, at time t0, the timer circuit 48 sets the signal S3 to the switch SW1 at H level to turn on the switch SW1. As a result, the driving current I1 is supplied only to the light-emitting element D1 of the light-emitting elements D1 and D2 of the first light source 21, and one light-emitting element (light-emitting element D1) is turned on.

[0063] At time t1, which is the time period Ta / 2 after time t0, the timer circuit 48 changes the signal S3 to an L level and turns off the switch SW1. As a result, the drive current I1 is supplied to the light-emitting elements D1 and D2 of the first light source 21, and the two light-emitting elements (light-emitting elements D1 and D2) are turned on.

[0064] Furthermore, at time t2, which is the time period Ta / 2 after time t1, the second control circuit 44 operates the switching regulator 42 based on the signal S4 from the timer circuit 48. As a result, the drive current I2 is supplied to the light-emitting elements D3 to D7 of the second light source 22, and the seven light-emitting elements (light-emitting elements D1 to D7) are turned on.

[0065] Furthermore, at time t3, which is the time period Tb after time t2, the switch 111 is controlled to be turned off. As a result, the turn voltage Vt becomes the L level (ground level) and the supply of power to the turn signal lamp 10 is stopped, so that the linear regulator 41, the switching regulator 42, and the like stop operating. Therefore, the supply of the drive current I1 to the light-emitting elements D1 and D2 and the supply of the drive current I2 to the light-emitting elements D3 to D7 are also stopped, so that the first light source 21 and the second light source 22 are turned off.

[0066] Then, at time t4, which is a period T2 (for example, 400 ms) after time t3 when the first light source 21 and the second light source 22 are turned off, the switch 111 is controlled to be turned on again. Therefore, after time t4, the operation from time t0 to time t4 is repeated in the cycle Tx.

[0067] <<Operation of the lights-out circuit 47>> 4, it has been described that none of the light-emitting elements D1 to D7 is disconnected, but if, for example, any of the light-emitting elements D1 to D7 is disconnected, the light-off circuit 47 stops the operations of the linear regulator 41 and the switching regulator 42. The operation of the light-off circuit 47 will be described below.

[0068] <State before disconnection is detected> During period T1, if no break is detected, voltage VCC (e.g., 5V) is applied to the base electrode of NPN transistor Q1 via resistor R2, so that NPN transistor Q1 turns on. This causes the charging voltage of capacitor C2 to be discharged via resistor R3 and NPN transistor Q1. Also, the charging voltage of capacitor C3 is lower than the threshold voltage of NMOS transistor Q3, so the voltage of node N1 is at L level, NMOS transistor Q3 turns off, and nodes N2 and N3 (output of light-off circuit 47) become H level. Also, because node N2 becomes H level, PNP transistor Q2 turns off.

[0069] <When a break is detected on the second light source 22 side> When the disconnection detection circuit 46 detects an abnormality in the second light source 22 and the signal S11 goes to L level, the NPN transistor Q1 turns off. As a result, the capacitors C2 and C3 are charged, the node N1 goes to H level, the NMOS transistor Q3 turns on, and the nodes N2 and N3 go to L level. Furthermore, the node N2 goes to L level, so that the PNP transistor Q2 turns on. Since the node N3 is at L level, the diodes 65 and 66 generate L level signals S12 and S14, respectively, at their anodes, which indicate an abnormality.

[0070] That is, the light-off circuit 47 outputs an L-level signal S12 to the first control circuit 43, and outputs an L-level signal S14 to the second control circuit 44. As a result, the first control circuit 43 stops the operation of the linear regulator 41, and the second control circuit 44 stops the operation of the switching regulator 42.

[0071] <When a break is detected on the first light source 21 side> When the disconnection detection circuit 45 detects an abnormality in the first light source 21 and the signal S13 goes low, a current flows from the base electrode of the NPN transistor Q1 to the supply line of the signal S13 via the diode D11. As a result, the voltage of the base electrode of the NPN transistor Q1 becomes the forward voltage of the diode D11 (e.g., 0.6 V), and the NPN transistor Q1 turns off. The rest of the process is similar to when the signal S11 goes low. In this case, the diodes 65 and 66 generate low-level signals S12 and S14, respectively, at their anodes, which indicate an abnormality.

[0072] In this case as well, the light-off circuit 47 outputs an L-level signal S12 to the first control circuit 43, and outputs an L-level signal S14 to the second control circuit 44. As a result, the first control circuit 43 stops the operation of the linear regulator 41, and the second control circuit 44 stops the operation of the switching regulator 42.

[0073] In this embodiment, the capacitor C3 and resistor R8 are provided in the extinguishing circuit 47, so that an L-level signal indicating an abnormality can be held for a predetermined period even when the voltage VCC is not supplied. In this embodiment, the capacitance value of the capacitor C2 and the resistance value of the resistor R8 are determined so that the output of the L-level signal can be held at least for the period (400 ms) when the turn voltage Vt is at the L level (preferably, for a period Tx or longer of the turn voltage Vt). This ensures that the operation of the lighting circuit 30 is stopped when an abnormality occurs.

[0074] To recover from the hold state, the turn signal ST is set to L level for at least the period Tx by operating the direction indicator. This causes the charging voltage of the capacitor C3 to be discharged through the resistor R8, the voltage of the node N1 becomes lower than the threshold of the NMOS transistor Q3, and the hold state is released. After that, the turn signal ST is set to H level again.

[0075] In this embodiment, a diode D13 is provided between node N4 of the extinguishing circuit 47 and node N1 (in other words, capacitor C3). This is because if the diode D13 is not provided, the NPN transistor Q1 turns on when the turn voltage Vt becomes H level, and at that time, the charging voltage of the capacitor C3 is discharged and the holding state is released. When the holding state is released, the input current Iin flows to the lighting circuit 30, and the open circuit detection circuit 115 on the vehicle side may erroneously detect that there is no open circuit.

[0076] 5 is a diagram for explaining the effect of the diode D13. The upper part of the diagram shows the turn voltage Vt, the middle part shows the input current Iin when the diode D13 is not provided (comparative example), and the lower part shows the input current Iin when the diode D13 is provided (embodiment).

[0077] When an open circuit is detected (the output of either of the open circuit detection circuits 45, 46 becomes L level) at the time indicated by the dashed line during the period when the turn voltage Vt is at H level, the light-out circuit 47 stops the operation of the linear regulator 41 and the switching regulator 42, so that the input current Iin stops flowing. Note that, as the operation of the linear regulator 41 and the switching regulator 42 stops (the output voltage becomes zero), the outputs of the open circuit detection circuits 45, 46 both become H level.

[0078] When the turn voltage Vt becomes the L level, the voltage VCC is no longer supplied, but in this embodiment, since the capacitor C3 is charged, the NMOS transistor Q3 remains on.

[0079] In the comparative example (without diode D13), the next time the turn voltage Vt reaches H level, the voltage VCC is supplied and the NPN transistor Q1 turns on. This causes the charge in the capacitor C3 to be discharged via the NPN transistor Q1. This releases the hold state and causes the input current Iin to flow as shown in FIG. 5. Similarly, every time the turn voltage Vt reaches H level, the hold state is released and the input current Iin flows. In such a case, the flow of the input current Iin may cause the vehicle-side disconnection detection circuit 115 to make an erroneous detection.

[0080] In contrast, in this embodiment, since the diode D13 is provided, the charge in the capacitor C3 is not discharged even if the voltage VCC is supplied and the NPN transistor Q1 is turned on at the timing when the turn voltage next becomes H level. Therefore, the holding state is reliably continued, and the state in which the input current Iin does not flow is maintained as shown in the figure. This makes it possible to prevent erroneous detection by the break detection circuit 115. Note that the diode D13 is not necessarily provided. For example, if the time constant of the capacitor C3 and the resistor R8 is very large, the diode D13 is not necessary.

[0081] <<<Other embodiments>>> For example, the first light source 21 includes two light emitting elements D1 and D2, and the second light source includes five light emitting elements D3 to D7, but is not limited to this. For example, the first light source 21 may include three light emitting elements.

[0082] In addition, in the above-described embodiment, the light-emitting elements D3 to D7 of the second light source 22 were turned on simultaneously at time t2, but a switch may be provided in parallel with each of the light-emitting elements D3 to D7, and the light-emitting elements D3 to D7 may be turned on sequentially by controlling each switch.

[0083] In addition, in this embodiment, two light sources, the first light source 21 and the second light source 22, are provided, but this is not limited thereto, and one or three or more light sources may be provided. When there is one light source, one regulator, one disconnection detection circuit, and one control circuit may also be provided. When there are three or more light sources, the regulator, the disconnection detection circuit, and the control circuit may be provided so as to correspond to each light source, as in this embodiment, and when a disconnection is detected in even one light source, all the light sources may be turned off.

[0084] In addition, the lighting circuit 30 is provided with a linear regulator 41 as a regulator that supplies the driving current I1 to the first light source 21, and a switching regulator 42 as a regulator that supplies the driving current I2 to the second light source 22, but this is not limited to the above. For example, the linear regulator and the switching regulator may be reversed, or the same type of regulator may be used. Furthermore, a regulator other than a linear regulator and a switching regulator may be used.

[0085] ===Summary=== The turn signal lamp 10 of the present embodiment has been described above. The lighting circuit 30 includes a power line L1 to which a power supply voltage Vbat is supplied during the period T1 and the supply of the power supply voltage Vbat is stopped during the period T2 of a cycle Tx including the periods T1 and T2, a linear regulator 41 that supplies a drive current I1 to a light source (here, the first light source 21) based on the power supply voltage Vbat of the power line L1, a disconnection detection circuit 45 that detects whether or not there is an abnormality in the first light source 21, a light-off circuit 47 that operates based on the power supply voltage Vbat of the power line L1 and outputs a signal S14 according to the detection result of the disconnection detection circuit 45, and a first control circuit 43 that stops the operation of the linear regulator 41 when the signal S14 indicating that there is an abnormality in the first light source 21 is output. When the detection result indicating that there is an abnormality in the first light source 21 is input during the period T1, the light-off circuit 47 holds the signal S14 indicating that there is an abnormality in the first light source 21 regardless of whether or not the power supply voltage Vbat is supplied to the power line L1. This ensures that the operation of the linear regulator 41 is stopped even during the period T2. Therefore, the lighting circuit 30 can reliably stop its operation when an abnormality occurs.

[0086] Furthermore, the extinguishing circuit 47 includes a charging circuit that charges the capacitor C3 when a detection result (signal S13) indicating that there is an abnormality in the first light source 21 is input during the period T1, and a holding circuit (inverters 61, 62, etc.) that includes the capacitor C3 and holds a signal S14 indicating that there is an abnormality in the first light source 21 when the charging voltage of the capacitor C3 reaches a predetermined level. This makes it possible to hold the signal S14 indicating that there is an abnormality even during the period T2 when the power supply voltage Vbat is not supplied.

[0087] The holding circuit includes an NMOS transistor Q3 whose gate electrode is connected to the capacitor C3 and whose state changes when the charging voltage of the capacitor C3 reaches a predetermined level (threshold voltage), and a resistor R8 connected in parallel to the capacitor C3, and the resistor R8 has a resistance value that prevents the charging voltage of the capacitor C3 from becoming lower than the predetermined level during the period T2. This allows the NMOS transistor Q3 to be held in the on state during the period T2.

[0088] The charging circuit also includes an NPN transistor Q1 that turns off based on a detection result (signal S13) indicating that there is an abnormality in the first light source during period T1, and a resistor R4 that supplies a charging current to the capacitor C3 when the NPN transistor Q1 turns off. As a result, when an abnormality is detected during period T1, the NPN transistor Q1 turns off, so that the capacitor C3 can be charged.

[0089] The light-off circuit 47 also includes a capacitor C2 connected to a node N4 to which the NPN transistor Q1 and resistor R4 are connected, and a diode D13 having an anode connected to the node N4 and a cathode connected to the capacitor C3. This makes it possible to prevent the charged voltage of the capacitor C3 from being discharged via the NPN transistor Q1 when the turn voltage Vt switches from the L level to the H level, and to prevent the hold state from being released.

[0090] The turn signal lamp 10 of this embodiment includes a first light source 21 and a second light source as light sources, and includes a linear regulator 41 that supplies a drive current I1 to the first light source 21 based on the power supply voltage Vbat of the power supply line L1, a disconnection detection circuit 45 that detects the presence or absence of an abnormality in the first light source 21, a switching regulator 42 that supplies a drive current I2 to the second light source 22 based on the power supply voltage Vbat of the power supply line L1, and a disconnection detection circuit 46 that detects the presence or absence of an abnormality in the second light source 22. The extinguishing circuit 47 operates based on the power supply voltage Vbat of the power supply line L1, and outputs signals S12 and S14 based on the detection result (signal S13) of the disconnection detection circuit 45 and the detection result (signal S11) of the disconnection detection circuit 46. Furthermore, the device is provided with a first control circuit 43 that stops the operation of the linear regulator 41 when a signal (signals S12, S14) indicating that there is an abnormality in either the first light source 21 or the second light source 22 is output, and a second control circuit 44 that stops the operation of the switching regulator 42. Then, when a detection result (L-level signal S13) indicating that there is an abnormality in the first light source 21 or a detection result (L-level signal S11) indicating that there is an abnormality in the second light source 22 is input during the period T1, the extinguishing circuit 47 holds a signal (signals S12, S14) indicating that there is an abnormality in either the first light source 21 or the second light source 22, regardless of whether the power supply voltage Vbat is supplied to the power supply line L1. This allows the lighting circuit 30 to reliably stop operation when an abnormality occurs in either the first light source 21 or the second light source 22.

[0091] The above-mentioned embodiment is for the purpose of facilitating understanding of the present invention, and is not intended to limit the present invention. Furthermore, the present invention can be modified or improved without departing from the spirit of the present invention, and it goes without saying that the present invention includes equivalents thereof. [Explanation of symbols]

[0092] 10 Turn signal lamp 21 1st light source 22 Second light source 30 Lighting circuit 40 VCC circuit 41 Linear regulator 42 Switching Regulator 43 First control circuit 44 Second control circuit 45,46 Open circuit detection circuit 47 Lights-off circuit 48 Timer Circuit 51,52 Resistance 53 Comparator 61,62 Inverter 65,66 Diodes 101 Battery 110 Body Control Module (BCM) 111 Switch 115 Disconnection detection circuit A~H terminals D1 to D7 Light emitting elements C1~C3 capacitors D11~D14 Diodes Q1 NPN transistor Q2 PNP transistor Q3 NMOS transistor R1~R8 Resistors L1 Power line N1~N4 nodes SW1 Switch Vbat power supply voltage Vt Turn voltage

Claims

1. A lighting circuit applied to a vehicle lamp, a power supply line to which a power supply voltage is supplied during a first period and to which the supply of the power supply voltage is stopped during a second period of a predetermined cycle including a first period and a second period; a regulator that supplies a drive current to a light source based on the power supply voltage of the power supply line; a detection circuit for detecting the presence or absence of an abnormality in the light source; a signal output circuit that operates based on the power supply voltage of the power supply line and outputs a signal corresponding to a detection result of the detection circuit; a control circuit that stops the operation of the regulator when the signal indicating that the light source is abnormal is output; Equipped with The signal output circuit includes: a charging circuit that charges a first capacitor when the detection result indicating that an abnormality exists in the light source during the first period is input; a holding circuit including the first capacitor, the holding circuit holding the signal indicating that an abnormality exists in the light source when a charging voltage of the first capacitor reaches a predetermined level; Including, The holding circuit includes: a first transistor having a control electrode connected to the first capacitor, the first transistor changing state when the charging voltage of the first capacitor reaches the predetermined level; a first resistor connected in parallel with the first capacitor; having the first resistor has a resistance value that prevents the charging voltage of the first capacitor from becoming lower than the predetermined level during the second period; The charging circuit includes: a second transistor that is turned off based on the detection result indicating that there is an abnormality in the light source during the first period; a second resistor that supplies a charging current to the first capacitor when the second transistor is turned off; Including, Lighting circuit.

2. 2. The lighting circuit according to claim 1, a second capacitor connected to a node to which the second transistor and the second resistor are connected; a diode having an anode connected to the node and a cathode connected to the first capacitor; Including a lighting circuit.

3. The light source; A lighting circuit according to claim 1 or 2; A vehicle lamp comprising:

4. A power supply line, to which a power supply voltage is supplied during a first period and which is stopped from being supplied during a second period of a predetermined cycle including a first period and a second period; a first regulator that supplies a first driving current to a first light source based on the power supply voltage of the power supply line; a first detection circuit that detects whether or not there is an abnormality in the first light source; a second regulator that supplies a second driving current to a second light source based on the power supply voltage of the power supply line; a second detection circuit that detects whether or not there is an abnormality in the second light source; a signal output circuit that operates based on the power supply voltage of the power supply line and outputs a signal based on a first detection result of the first detection circuit and a second detection result of the second detection circuit; a first control circuit that stops the operation of the first regulator when the signal indicating that an abnormality exists in either the first or second light source is output; a second control circuit that stops the operation of the second regulator when the signal indicating that an abnormality exists in either the first or second light source is output; Equipped with The signal output circuit includes: a charging circuit that charges a first capacitor when the first detection result indicating that an abnormality exists in the first light source or the second detection result indicating that an abnormality exists in the second light source is input during the first period; a holding circuit including the first capacitor, the holding circuit holding the signal indicating that an abnormality exists in either the first or second light source when a charging voltage of the first capacitor reaches a predetermined level; Including, The holding circuit includes: a first transistor having a control electrode connected to the first capacitor, the first transistor changing state when the charging voltage of the first capacitor reaches the predetermined level; a first resistor connected in parallel with the first capacitor; having the first resistor has a resistance value that prevents the charging voltage of the first capacitor from becoming lower than the predetermined level during the second period; The charging circuit includes: a second transistor that is turned off based on the first detection result indicating that an abnormality exists in the first light source during the first period or the second detection result indicating that an abnormality exists in the second light source; a second resistor that supplies a charging current to the first capacitor when the second transistor is turned off; Including, Lighting circuit.

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