Lighting module

Abstract

To provide a lighting module capable of detecting an abnormality of an open of a light source while suppressing heat generation.SOLUTION: A lighting module is a lighting module that is adapted to n(n>1) light fixture that is serially connected, comprises: a pressure rise circuit that rises a first voltage, and outputs a second voltage at a first level; a driving circuit that supplies a predetermined driving current to n light sources on the basis of the second voltage; and a control circuit that makes the pressure rise circuit to output the second voltage at a second level that is higher than the first level when a state of the driving circuit becomes an abnormality, and performs a detection of the light source in which an open abnormality of the n light sources occurs.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a lighting module.

Background Art

[0002] As a lighting module applied to vehicle lamps, there is a module including a drive circuit that supplies a constant current to a plurality of serially connected light sources to turn them on (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the voltage applied by the drive circuit of the lighting module to a plurality of light sources is set high in consideration of the case where an open abnormality occurs in any of the plurality of light sources. However, when the drive circuit lights a plurality of light sources, applying a high voltage to the plurality of light sources increases the heat generation (or power consumption) of the lighting module and the plurality of light sources.

[0005] An object of the present invention is to provide a lighting module capable of detecting an open abnormality of a light source while suppressing heat generation.

Means for Solving the Problems

[0006] The main invention of the present application for solving the above problems is a lighting module applied to a luminaire including n (n>1) light sources connected in series, the lighting module including: a boost circuit that boosts a first voltage and outputs a second voltage at a first level; a drive circuit that supplies a predetermined drive current to the n light sources based on the second voltage; and a control circuit that, when the state of the drive circuit becomes abnormal, causes the boost circuit to output the second voltage at a second level higher than the first level, and detects a light source in which an open-circuit abnormality has occurred among the n light sources.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a lighting module that can detect an open-circuit abnormality of a light source while suppressing heat generation.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0009] At least the following matters are clarified by the description in this specification and the attached drawings.

[0010] =====First Embodiment===== <<Configuration of Vehicle Lamp 1>> FIG. 1 is a diagram showing an example of the configuration of a vehicle lamp 1 using the lighting module 40a of the present embodiment.

[0011] The vehicle lamp 1 is a lamp that lights the first light source 10, the second light source 20, and the third light source 30 based on the voltage Vbat of the vehicle battery 2. The vehicle lamp 1 includes the first light source 10, the second light source 20, the third light source 30, and the lighting module 40a.

[0012] <The first light source 10> The first light source 10 is, for example, a light source for a low beam, and is connected between a terminal E and a terminal F (described later) of the lighting module 40a. Note that the low beam illuminates the vicinity of the host vehicle, and light distribution regulations are defined so as not to give glare to oncoming vehicles or preceding vehicles, and it is mainly used when driving in urban areas.

[0013] The first light source 10 includes at least one light emitting element 11. In the present embodiment, a light emitting diode (LED) is used as the light emitting element 11. However, it is not limited to an LED, and other semiconductor light emitting elements such as a laser diode (LD) or an organic EL element may be used. Note that the same element (LED) as the light emitting element 11 of the second light source 20 and the light emitting element 31 of the third light source described later is also used.

[0014] Also, in FIG. 1, for the sake of simplicity, the number of the light emitting elements 11 of the first light source 10 is set to one, but in the first light source 10 of the present embodiment, a plurality (for example, six) of the light emitting elements 11 are connected in series. Further, the voltage at both ends of the first light source 10 when it is lit is, for example, 12V as a standard value. Further, the voltage generated at both ends of the first light source 10 when the first light source 10 is lit is, for example, 15V as a maximum value. Hereinafter, the forward voltage of one light emitting element is, for example, 2V. The "standard value of the voltage at both ends of the light source" is the voltage value when the forward voltage of the light emitting element is a standard value within the range that can be obtained due to manufacturing variations, temperature characteristics of the light emitting element, etc., and the "maximum value of the voltage at both ends of the light source" is the voltage value when the forward voltage of the light emitting element is the maximum value within the range that can be obtained due to manufacturing variations, temperature characteristics of the light emitting element, etc.

[0015] <The second light source 20> The second light source 20 is, for example, a light source for high beams, and is connected between a terminal G and a terminal H (described later) of the lighting module 40a. The high beams illuminate a wide range and the distance ahead of the vehicle, and are mainly used when driving at high speed on a road with few oncoming vehicles and preceding vehicles. As will be described later, since the terminal F and the terminal G are connected in the lighting module 40a, the second light source 20 is connected in series with the first light source 10.

[0016] Also, the second light source 20 includes at least one light-emitting element 21. In FIG. 1, for simplicity, the number of light-emitting elements 21 of the second light source 20 is set to one, but in the second light source 20 of the present embodiment, a plurality (for example, 10) of light-emitting elements 21 are connected in series. Also, the voltage across both ends of the second light source 20 when it is lit is, for example, 20V as a standard value. Also, the voltage generated across both ends of the second light source 20 when the second light source 20 is lit is, for example, 25V as a maximum value.

[0017] <The third light source 30> The third light source 30 is, for example, a light source for position lamps, and is connected between a terminal I and a terminal J (described later) of the lighting module 40a. The position lamps indicate the width of the vehicle, are also called side marker lamps, and are provided near the left and right ends in front of the vehicle. As will be described later, since the terminal H and the terminal I are connected in the lighting module 40a, the third light source 30 is connected in series with the first light source 10 and the second light source 20.

[0018] Also, the third light source 30 includes at least one light-emitting element 31. In FIG. 1, for simplicity, the number of light-emitting elements 31 of the third light source 30 is set to one, but in the third light source 30 of the present embodiment, a plurality (for example, 2) of light-emitting elements 31 are connected in series. Also, the voltage across both ends of the third light source 30 when it is lit is, for example, 4V as a standard value. Also, the voltage generated across both ends of the third light source 30 when the third light source 30 is lit is, for example, 5V as a maximum value.

[0019] Also, in the present embodiment, when a predetermined constant current is supplied to the first light source 10, the second light source 20, and the third light source 30, and each light source is emitting light, as shown in FIG. 2, for example, the voltages generated at both ends of each of the first light source 10, the second light source 20, and the third light source 30 are at most 15V, 25V, and 5V, respectively. Therefore, if at least 45V is applied to the first light source 10, the second light source 20, and the third light source 30 connected in series, these light sources will light up. Note that the first light source 10, the second light source 20, and the third light source 30 correspond to the "n light sources".

[0020] Also, as described above, in order to light all the light sources while suppressing heat generation (or power consumption) in the lighting module 40a and the light sources, the lighting module 40a may apply 45V to the terminal E on the power supply side of the first light source 10. However, when an open-circuit abnormality occurs in the light-emitting element of the light source, if 45V is continuously applied, the detection circuits 44 to 46 (described later) cannot detect the element in which the open-circuit abnormality has occurred.

[0021] On the other hand, the lighting module 40a of the present embodiment is a circuit that can detect an open-circuit abnormality when an open-circuit abnormality occurs. Note that the "open-circuit abnormality" refers to an abnormality in which a disconnection occurs in the light-emitting element and the light-emitting element is in a non-lighting state.

[0022] <lighting module 40a> The lighting module 40a is a circuit that is applied to the vehicle lamp 1 and lights the first light source 10, the second light source 20, and the third light source 30 in accordance with an instruction from a control device (not shown: hereinafter also referred to as the vehicle-side ECU) provided on the vehicle side. The lighting module 40a of the present embodiment includes a boost circuit 41, a drive circuit 42, a microcomputer 43a, detection circuits (DET) 44 to 46, switches SW1, SW2, SW3, and terminals A to J. Note that the lighting module 40a is a module in which each of the above circuits and each terminal is attached to a substrate CB.

[0023] In addition, in this embodiment, the boost circuit 41, drive circuit 42, microcomputer 43a, etc. of the lighting module 40a are attached to one substrate CB, but it is not limited to this. For example, the lighting module may be a module including a substrate on which the boost circuit 41, drive circuit 42, etc. are mounted and a substrate on which the microcomputer 43a is mounted. Also, in such a case, the substrate on which the boost circuit 41, etc. are mounted and the substrate on which the microcomputer 43a is mounted are connected by a cable or the like.

[0024] On the substrate CB, a boost circuit 41, a drive circuit 42, a microcomputer 43a, detection circuits 44 to 46, switches SW1, SW2, SW3, and terminals A to J are provided.

[0025] Terminal A is a terminal connected to the positive electrode of the battery 2, and a power supply voltage (voltage Vbat) is applied from the battery 2.

[0026] Terminal B is a terminal connected to the negative electrode of the battery 2, and a voltage at the ground level is applied from the battery 2.

[0027] Terminal C is a terminal to which a control signal S1 is input from the vehicle-side ECU. Note that the control signal S1 is a signal for instructing the lighting and extinguishing of the first light source 10, the second light source 20, and the third light source 30.

[0028] Terminal D is a terminal for outputting a detection signal S2 to the vehicle-side ECU. Note that the detection signal S2 is a signal indicating that an abnormality has been detected in at least one of the first light source 10, the second light source 20, and the third light source 30.

[0029] Terminals E and F are terminals for connecting the first light source 10. Also, an output voltage Vout of the drive circuit 42 is applied to terminal E.

[0030] Terminals G and H are terminals for connecting the second light source 20. Also, within the lighting module 40a, terminal G is connected to terminal F, and terminal H is connected to terminal I.

[0031] Terminal I and terminal J are terminals for connecting the third light source 30. Also, within the lighting module 40a, terminal I is connected to terminal H, and terminal J is connected to terminal B.

[0032] Switch SW1 is a switch provided between terminal E and terminal F (in other words, in parallel with the first light source 10). When switch SW1 is on (conductive), a path is formed for current to be supplied to the second light source 20 bypassing the first light source 10. As a result, since no current is supplied to the first light source 10, the first light source 10 does not light up and is in the off state. On the other hand, when switch SW1 is off (non-conductive), current is supplied to the first light source 10, and the first light source 10 is in the on state.

[0033] Switch SW2 is a switch provided between terminal G and terminal H (in other words, in parallel with the second light source 20). When switch SW2 is on, a path is formed to bypass the second light source 20. As a result, since no current is supplied to the second light source 20, the second light source 20 does not light up and is in the off state. On the other hand, when switch SW2 is off, current is supplied to the second light source 20, and the second light source 20 is in the on state.

[0034] Switch SW3 is a switch provided between terminal I and terminal J (in other words, in parallel with the third light source 30). When switch SW3 is on, a path is formed to bypass the third light source 30. As a result, since no current is supplied to the third light source 30, the third light source 30 does not light up and is in the off state. On the other hand, when switch SW3 is off, current is supplied to the third light source 30, and the third light source 30 is in the on state. Note that switches SW1 to SW3 correspond to the "n switches".

[0035] The boost circuit 41 is a circuit that boosts the voltage V1 (i.e., the voltage Vbat of the battery 2) and outputs the voltage V2, and is provided between the terminal A and the drive circuit 42. The boost circuit 41 normally outputs the voltage V2 at the voltage level LV1, and outputs the voltage V2 at the voltage level LV2 based on the control signal Scntl from the microcomputer 43a (described later). Also, the voltage level LV2 is higher than the voltage level LV1. Note that the voltage V1 corresponds to the "first voltage", the voltage V2 corresponds to the "second voltage", the voltage level LV1 corresponds to the "first level", and the voltage level LV2 corresponds to the "second level".

[0036] By the way, in the present embodiment, when the drive circuit 42 (described later) supplies a constant current to the first light source 10, the second light source 20, and the third light source 30, if an open abnormality occurs in one light-emitting element, the voltage level difference between both ends of the light-emitting element when the open abnormality occurs and when normal is larger than 2V which is the forward voltage. Note that the "voltage level difference between both ends of the light-emitting element" is the voltage level difference between the cathode and the anode of the light-emitting element.

[0037] Although details will be described later, when the state of the drive circuit 42 becomes abnormal and the level difference before and after the rise (for example, 12V) when raising the output voltage in the boost circuit 41 is larger than the level difference of the voltage change (for example, 10V) generated at both ends of one light-emitting element when one light-emitting element has an open abnormality.

[0038] Thereby, the lighting module 40a can detect an open abnormality of the light source while suppressing heat generation (or power consumption) during normal times.

[0039] The drive circuit 42 is a circuit (constant current circuit) that outputs a predetermined drive current Iout for turning on the first light source 10, the second light source 20, and the third light source 30 based on the voltage V2, and is provided between the boost circuit 41 and the terminal E. When the state of the drive circuit 42 becomes abnormal (i.e., a short circuit or an open circuit in the output of the drive circuit 42), the drive circuit 42 outputs a signal Sfault. The drive circuit 42 is composed of, for example, a buck-type switching regulator (DC-DC converter). Note that the drive circuit 42 is not limited to a switching regulator and may be, for example, a linear regulator.

[0040] Note that the short circuit of the output of the drive circuit 42 refers to, for example, a state in which the node to which the output voltage Vout is applied is connected to the ground. Also, the open circuit of the output of the drive circuit 42 refers to a state in which the current value of the drive current Iout is sufficiently smaller than a predetermined value.

[0041] The microcomputer 43a is a circuit that controls the operation of the vehicle lamp 1, details of which will be described later. The microcomputer 43a turns on and off the switches SW1 to SW3 to turn on or off the first light source 10, the second light source 20, and the third light source 30. The microcomputer 43a detects that an abnormality has occurred in the drive circuit 42 based on the signal Sfault from the drive circuit 42.

[0042] Specifically, the microcomputer 43a detects the signals Sv1, Sv2, and Sv3 from the respective detection circuits 44 to 46 (described later) based on the signal Sfault. Then, the microcomputer 43a detects which of the first light source 10, the second light source 20, or the third light source 30 has an abnormality based on the signals Sv1, Sv2, and Sv3.

[0043] Also, the microcomputer 43a outputs a signal Scntl to cause the boost circuit 41 to output the voltage V2 at the voltage level LV2. The signal Siup will be described later.

[0044] Note that the microcomputer 43a is realized by elements and circuits including a computer's CPU, memory, etc. as its hardware configuration, and is realized by a computer program or the like as its software configuration. Also, the microcomputer 43a corresponds to a "control circuit".

[0045] The detection circuit (DET) 44 includes, for example, resistors 441 and 442, and is provided between terminals E and F (in other words, in parallel with the first light source 10), and is a voltage dividing circuit that detects the voltage between terminals E and F, and outputs a signal Sv1 corresponding to the voltage between terminals E and F. Specifically, when the first light source 10 lights up normally, 15V is applied to the first light source 10, and the detection circuit 44 outputs a signal Sv1 indicating normal lighting. On the other hand, when an open circuit abnormality occurs in the first light source 10, 25V is applied to the first light source 10, and the detection circuit 44 outputs a signal Sv1 indicating overvoltage. Note that when the first light source 10 is short-circuited, the detection circuit 44 outputs a signal Sv1 indicating a short circuit.

[0046] The detection circuit 45 includes, for example, resistors 451 and 452, and is provided between terminals G and H (in other words, in parallel with the second light source 20), and is a voltage dividing circuit that detects the voltage between terminals G and H, and outputs a signal Sv2 corresponding to the voltage between terminals G and H. Specifically, when the second light source 20 lights up normally, 25V is applied to the second light source 20, and the detection circuit 45 outputs a signal Sv2 indicating normal lighting. On the other hand, when an open circuit abnormality occurs in the second light source 20, 35V is applied to the second light source 20, and the detection circuit 45 outputs a signal Sv2 indicating overvoltage. Note that when the second light source 20 is short-circuited, the detection circuit 45 outputs a signal Sv2 indicating a short circuit.

[0047] The detection circuit 46 includes, for example, resistors 461 and 462, and is provided between terminal I and terminal J (in other words, in parallel with the third light source 30). It is a voltage-dividing circuit that detects the voltage between terminal I and terminal J and outputs a signal Sv3 corresponding to the voltage between terminal I and terminal J. Specifically, when the third light source 30 lights up normally, 5V is applied to the third light source 30, and the detection circuit 46 outputs a signal Sv3 indicating normal lighting. On the other hand, when an open-circuit abnormality occurs in the third light source 30, 15V is applied to the third light source 30, and the detection circuit 46 outputs a signal Sv3 indicating overvoltage. In addition, when the third light source 30 is short-circuited, the detection circuit 46 outputs a signal Sv3 indicating a short circuit.

[0048] Note that, as the detection circuits 44 to 46, for example, a voltage-dividing circuit has been described. However, when it is detected that the voltage applied to each light source is higher than normal, a voltage detector (that is, a reset IC) that outputs a signal indicating that an overvoltage has been applied can also be used. In this case, a circuit for converting the voltage of the signal output by the voltage detector into a voltage that can be processed by the microcomputer 43a may be provided. Furthermore, a circuit that uses a comparator to detect an overvoltage, performs level conversion to a voltage that can be processed by the microcomputer 43a, and outputs a signal (for example, signal Sv1) indicating that an overvoltage has been applied may also be used. Also, for example, the voltage applied to the detection circuit 44 can be level-converted to a voltage that can be processed by the microcomputer 43a and used as the signal Sv1. In addition, the detection circuits 44 to 46 correspond to "n voltage detection circuits".

[0049] ===Operation of the microcomputer 43a === Hereinafter, with reference to FIG. 2, how the microcomputer 43a detects open-circuit abnormalities in the first light source 10, the second light source 20, and the third light source 30 will be described. In this embodiment, the open-circuit abnormality detection threshold values for the first light source 10, the second light source 20, and the third light source 30 are set to the voltage generated at both ends of the light source during normal operation plus a predetermined voltage Vdelta. In this embodiment, the voltage Vdelta is, for example, 10V, but it varies depending on the temperature characteristics of the light-emitting elements included in the light source, manufacturing variations, and the like.

[0050] <<Normal operation>> First, the normal operation of the lighting module 40a will be described. The boost circuit 41 boosts the voltage V1 and outputs a voltage V2 at a voltage level LV1. Here, the voltage level LV1 is a voltage level (for example, 45V) at which the first light source 10, the second light source 20, and the third light source 30 can be lit.

[0051] Then, when the voltage V2 is supplied from the boost circuit 41 to the drive circuit 42, the drive circuit 42 supplies an output voltage Vout (for example, 45V as shown in FIG. 2) and a drive current Iout. As a result, the lighting module 40a can light the three light sources.

[0052] <<Operation when there is an open fault in the first light source 10>> Here, the case where there is an open fault in the first light source 10 will be described. When an open fault occurs in the first light source 10, the light emitting element 11 of the first light source 10 becomes a high resistance, and the drive current Iout becomes small. Therefore, the drive circuit 42 outputs a signal Sfault indicating an abnormality to the microcomputer 43a.

[0053] When receiving the signal Sfault, the microcomputer 43a outputs a signal Scntl for causing the boost circuit 41 to output a voltage V2 at a voltage level LV2 in order to detect which light source has an open fault.

[0054] Upon receiving the signal Scntl, the boost circuit 41 outputs a voltage V2 with a voltage level LV2 (e.g., 57V). Then, as shown in FIG. 2, voltages are applied to the first light source 10, the second light source 20, and the third light source 30. At this time, if the boost is performed such that the voltage level LV2 becomes a voltage level that is higher than the voltage level LV1 by at least the voltage Vdelta, for example, an open abnormality of the first light source 10 can be detected. Note that the voltage values shown in FIG. 2 are for convenience of explanation. Since the drive current Iout from the drive circuit 42 decreases, voltages lower than the normal voltages are applied to the second light source 20 and the third light source 30. Also, when an open abnormality occurs in each of the second light source 20 and the third light source 30, the voltage applied to the normal light sources similarly decreases compared to the normal state.

[0055] As described above, here, an open abnormality has occurred in the first light source 10, and due to this, a voltage equal to or higher than the open abnormality detection threshold value (e.g., 25V as shown in FIG. 2) is applied to the first light source 10. In this case, the detection circuit 44 outputs a signal Sv1 indicating an overvoltage.

[0056] Then, based on the signals Sv1, Sv2, and Sv3 from the detection circuits 44 to 46, the microcomputer 43a detects that an open abnormality has occurred in the first light source 10. Thereafter, the microcomputer 43a turns on a switch (i.e., switch SW1) provided in parallel with the light source in which the open abnormality has occurred, and turns off the light source in which the open abnormality has occurred (i.e., the first light source 10). As a result, the light sources other than the first light source 10 (e.g., the second light source 20 and the third light source 30) can continue to be lit. Then, the microcomputer 43a outputs the signal Scntl so as to cause the boost circuit 41 to output the voltage V2 with the voltage level LV1. Thereby, heat generation of the lighting module 40a can be suppressed.

[0057] <<Operation when there is an open abnormality in the second light source 20>> Here, a case where there is an open abnormality in the second light source 20 will be described. Also, the operation until the boost circuit 41 receives the signal Scntl and outputs the voltage V2 with the voltage level LV2 (e.g., 57V) is as described above.

[0058] Then, voltages are applied to the first light source 10, the second light source 20, and the third light source 30 as shown in FIG. 2. As a result, a voltage equal to or higher than an open-fault detection threshold value (for example, 35 V as shown in FIG. 2) is applied to the second light source 20. In this case, the detection circuit 45 outputs a signal Sv2 indicating an overvoltage.

[0059] Then, the microcomputer 43a detects that an open fault has occurred in the second light source 20 based on the signals Sv1, Sv2, and Sv3 from the detection circuits 44 to 46. Thereafter, the microcomputer 43a turns on a switch (that is, the switch SW2) provided in parallel with the light source in which the open fault has occurred, and turns off the light source in which the open fault has occurred (that is, the second light source 20). As a result, light sources other than the second light source 20 (for example, the first light source 10 and the third light source 30) can continue to be lit. Then, the microcomputer 43a outputs a signal Scntl so as to cause the boost circuit 41 to output a voltage V2 having a voltage level LV1. Thereby, heat generation of the lighting module 40a can be suppressed.

[0060] <<Operation when there is an open fault in the third light source 30>> Here, a case where there is an open fault in the third light source 30 will be described. Also, the operation until the boost circuit 41 receives the signal Scntl and outputs a voltage V2 having a voltage level LV2 (for example, 57 V) is as described above.

[0061] Then, voltages are applied to the first light source 10, the second light source 20, and the third light source 30 as shown in FIG. 2. As a result, a voltage equal to or higher than an open-fault detection threshold value (for example, 15 V as shown in FIG. 2) is applied to the third light source 30. In this case, the detection circuit 46 outputs a signal Sv3 indicating an overvoltage.

[0062] Then, based on the signals Sv1, Sv2, and Sv3 from the detection circuits 44 to 46, the microcomputer 43a detects that an open abnormality has occurred in the third light source 30. After that, the microcomputer 43a turns on the switch (i.e., switch SW3) provided in parallel with the light source in which the open abnormality has occurred, and turns off the light source in which the open abnormality has occurred (i.e., the third light source 30). As a result, the light sources other than the third light source 30 (for example, the first light source 10 and the second light source 20) can continue to be lit. Then, the microcomputer 43a outputs a signal Scntl so as to cause the boost circuit 41 to output a voltage V2 at the voltage level LV1. Thereby, the heat generation of the lighting module 40a can be suppressed.

[0063] Thereby, it is possible to provide a lighting module that can detect an open abnormality of a light source while suppressing heat generation.

[0064] =====Second Embodiment===== By the way, when an open abnormality occurs in a light-emitting element, the voltage between both ends of the light source including the light-emitting element in which the open abnormality has occurred increases. Therefore, in the first embodiment, in order to detect the voltage between both ends, the output voltage Vout of the drive circuit 42 was boosted higher than normal.

[0065] However, it is also possible to apply a voltage capable of detecting an open abnormality to the light-emitting element in which the open abnormality has occurred without increasing the output voltage Vout of the drive circuit 42 further.

[0066] In the second embodiment, when the state of the drive circuit 42 becomes abnormal, any one of the switches SW1, SW2, and SW3 provided in parallel is turned on so that any one of the first light source 10, the second light source 20, and the third light source 30 is turned off.

[0067] As a result, the output voltage Vout from the drive circuit 42, for example, 45V, is not applied to the first light source 10, the second light source 20, and the third light source 30, but is applied to two of these light sources. As a result, the voltage applied across the light sources that are operating to light up (i.e., the light sources where the parallel switches SW1 to SW3 are off) can be increased. Therefore, in the case of the second embodiment, an open-circuit abnormality can be detected without increasing the output voltage Vout of the drive circuit 42 from, for example, 45V to 57V.

[0068] The lighting module 40b, which is the lighting module of the second embodiment, includes a boost circuit 41, a drive circuit 42, a microcomputer 43b, switches SW1, SW2, and SW3, and terminals A to J. Since components other than the microcomputer 43b are the same as those of the lighting module 40a, detailed description thereof is omitted. Also, similar to the case of the first embodiment, the microcomputer 43b and other circuits may be mounted on separate substrates, and the lighting module may be configured by connecting these substrates.

[0069] Hereinafter, a second embodiment using the microcomputer 43b that detects an open-circuit abnormality in the first light source 10, the second light source 20, or the third light source 30 without outputting the voltage V2 of the voltage level LV2 to the boost circuit 41 will be described. Note that the microcomputer 43b corresponds to a "control circuit".

[0070] <<Detection of Open-Circuit Abnormality in the Second Embodiment>> The boost circuit 41 boosts the voltage V1 and outputs a voltage V2 at a voltage level (for example, 45V) that can light up the first light source 10, the second light source 20, and the third light source 30.

[0071] Then, when the drive circuit 42 is supplied with the voltage V2 from the boost circuit 41 and supplies a predetermined drive current Iout, the voltage between the terminals connected to the light source where an open-circuit abnormality has occurred can increase.

[0072] And although the drive circuit 42 supplies the drive current Iout, when the output voltage Vout becomes an overvoltage, it outputs a signal Sfault indicating an abnormality to the microcomputer 43b.

[0073] When the microcomputer 43b receives the signal Sfault, it sequentially turns on the switches SW1 to SW3 one by one according to a predetermined pattern, outputs the signal Siup, and increases the current value of the drive current Iout supplied to the lit light source by the drive circuit 42. Specifically, as shown in FIG. 3, the pattern Pa is a pattern in which the switch SW1 among the switches SW1 to SW3 is turned on, and the pattern Pb is a pattern in which the switch SW2 among the switches SW1 to SW3 is turned on. And the pattern Pc is a pattern in which the switch SW3 among the switches SW1 to SW3 is turned on. Also, the pattern Pall is a pattern in which all the switches SW1 to SW3 are turned off. Note that descriptions other than the patterns Pa, Pb, Pc, and Pall will be described when explaining the operation of the lighting module 40b.

[0074] <<Operation of Microcomputer 43b>> Hereinafter, with reference to FIG. 4, the operation of the microcomputer 43b in the second embodiment will be described. In FIG. 4, it is described as if an open abnormality has occurred in the first light source 10. Also, except for the period T for detecting the open abnormality. In order to light the first light source 10, the second light source 20, and the third light source 30, it is assumed that the switches SW1 to SW3 are turned on and off by a PWM signal. Also, the off-duty of the switches SW1 to SW3 is determined so that an average current required when lighting each light source can flow. The total voltage in FIG. 4 is described assuming that an open abnormality has occurred in the first light source 10.

[0075] At time t0, the microcomputer 43b turns on the switch SW1 and turns off the first light source 10. On the other hand, the switches SW2 and SW3 are off. Also, in the case of this pattern Pa, as shown in FIG. 3, the voltage across both ends of the first light source 10 is 0V, the voltage across both ends of the second light source 20 is 25V, and the voltage across both ends of the third light source 30 is 5V. Therefore, the total voltage of the voltages generated across both ends of the first light source 10, the second light source 20, and the third light source 30 is 30V as shown in FIG. 3, which is lower than the voltage Vout of 45V. However, since the switch SW1 is turned on and the first light source 10 is off, in the case of pattern Pa, it is impossible to detect that an open abnormality has occurred in the first light source 10. That is, as shown in FIG. 3, the detection of an open abnormality is impossible.

[0076] At time t1, the microcomputer 43b turns off the switch SW1. Thereafter, all of the switches SW1 to SW3 are turned off, and the total voltage becomes 55V, which is higher than the voltage Vout as shown in FIG. 3. Therefore, in the case of pattern Pall, as shown in FIG. 3, the detection of an open abnormality is impossible.

[0077] At time t2, the microcomputer 43b turns on the switch SW2 and turns off the second light source 20. On the other hand, the switches SW1 and SW3 are off. Also, in the case of this pattern Pb, as shown in FIG. 3, the voltage across both ends of the first light source 10 becomes 25V, the voltage across both ends of the second light source 20 becomes 0V, and the voltage across both ends of the third light source 30 becomes 5V. Therefore, the total voltage becomes 30V as shown in FIG. 3, which is lower than the voltage Vout. Therefore, an open abnormality occurring in the first light source 10 can be detected. That is, as shown in FIG. 3, the detection of an open abnormality is possible.

[0078] At time t3, the microcomputer 43b turns off the switch SW2, resulting in pattern Pall.

[0079] At time t4, the microcontroller 43b turns on switch SW3 and turns off the third light source 30. On the other hand, switches SW1 and SW2 are off. Also, in the case of this pattern Pc, as shown in FIG. 3, the voltage across both ends of the first light source 10 is 25V, the voltage across both ends of the second light source 20 is 25V, and the voltage across both ends of the third light source 30 is 0V. Therefore, as shown in FIG. 3, the total voltage is 50V, which is higher than the voltage Vout. Therefore, an open abnormality of the first light source 10 cannot be detected. That is, as shown in FIG. 3, detection of an open abnormality is impossible.

[0080] At time t5, the microcontroller 43b turns off switch SW3, resulting in pattern Pall.

[0081] After time t6, the operation from time t0 to t6 (i.e., the period T) is repeated until it can be confirmed that the detection of an open abnormality occurring in the first light source 10 is not a false detection. Thereby, false detection of an open abnormality can be suppressed.

[0082] As described above, the operation of the microcontroller 43b has been described assuming that an open abnormality has occurred in the first light source 10. However, the same applies when an open abnormality occurs in the light emitting elements of the other second light source 20 and third light source 30. For example, when an open abnormality occurs in the second light source 20, the open abnormality can be detected in the case of pattern Pa in FIG. 3. Also, when an open abnormality occurs in the third light source 30, the open abnormality can be detected in the case of patterns Pa and Pb in FIG. 3.

[0083] Thereby, it is possible to provide a lighting module that can detect an open abnormality of a light source while suppressing heat generation.

[0084] Also, in the second embodiment, when switches SW1 to SW3 are turned on as described above and the three light sources are turned off in order, the brightness when the three light sources are lit becomes darker. Therefore, the microcontroller 43b increases the drive current Iout of the drive circuit 42 so that the brightness of these three light sources becomes substantially equal to the normal brightness.

[0085] Therefore, in the second embodiment, even when the open abnormality detection process is being executed, the brightness of the lit light sources can be made substantially equal to the brightness when the three light sources are normally lit.

[0086] =====Summary===== As described above, the vehicle lamp 1 of the present embodiment has been explained. The lighting module 40a of the vehicle lamp 1 includes a boost circuit 41 that boosts the voltage V1 and outputs a voltage V2 at a voltage level LV1, a drive circuit 42 that supplies a predetermined drive current Iout to a plurality of light sources based on the voltage V2, and when the state of the drive circuit 42 becomes abnormal, a microcomputer 43a that causes the boost circuit 41 to output a voltage V2 at a voltage level LV2 higher than the voltage level LV1 to detect a light source in which an open abnormality has occurred among the plurality of light sources. Thereby, it is possible to provide a lighting module that can detect an open abnormality of a light source while suppressing heat generation.

[0087] Further, each of the first light source 10, the second light source 20, and the third light source 30 includes at least one light-emitting element, and the level difference between the voltage levels LV1 and LV2 (for example, 12V) is larger than the level difference of the voltage change (for example, 10V) that occurs across one light-emitting element when one light-emitting element has an open abnormality. Thereby, it is possible to apply a voltage sufficient to detect an open abnormality to the light source (for example, the first light source 10) in which an open abnormality has occurred in the light-emitting element.

[0088] Further, the lighting module 40a includes switches SW1 to SW3 connected in parallel to each of the first light source 10, the second light source 20, and the third light source 30, and the microcomputer 43a turns on the switch (for example, switch SW1) provided in parallel with the light source (for example, the first light source 10) in which an open abnormality has occurred. Thereby, the light source (for example, the first light source 10) in which an open abnormality has occurred can be turned off, and the other light sources (for example, the second light source 20, the third light source 30) can continue to be lit.

[0089] Further, it includes detection circuits 44 to 46 provided in parallel to each of the first light source 10, the second light source 20, and the third light source 30. The microcomputer 43a detects a light source (for example, the first light source 10) in which an open abnormality has occurred based on the outputs from the detection circuits 44 to 46. Thus, while the signal Sfault can only detect that an open abnormality has occurred in one of the light sources, when detecting the outputs of the detection circuits 44 to 46, it is possible to detect in which of the light sources an open abnormality has occurred.

[0090] Also, the lighting module 40b of the vehicle lamp 1 includes switches SW1 to SW3 connected in parallel to each of the first light source 10, the second light source 20, and the third light source 30, a drive circuit 42 that supplies a predetermined drive current Iout to the light sources, and a microcomputer 43b that controls the on / off of the switches SW1 to SW3 to turn on or off each light source. Further, when the state of the drive circuit 42 becomes abnormal, the microcomputer 43b turns on at least one of the switches SW1 to SW3 and detects the light source in which an open abnormality has occurred among the light sources. Thereby, it is possible to provide a lighting module that can detect an open abnormality of a light source while suppressing heat generation.

[0091] Also, when the state of the drive circuit 42 becomes abnormal, the microcomputer 43b turns on at least one of the switches SW1 to SW3 in a predetermined order and detects the light source in which an open abnormality has occurred. Thereby, it is possible to detect the light source in which an open abnormality has occurred without increasing the output voltage Vout of the drive circuit 42.

[0092] Also, while the microcomputer 43b is turning on at least one of the switches SW1 to SW3 in a predetermined order (that is, during the period T), the microcomputer 43b increases the current value of the drive current Iout in the drive circuit 42. Thereby, even when performing the detection process of the open abnormality, the brightness of the lit light source can be made substantially equal to the brightness when the three light sources are normally lit.

[0093] Further, the microcomputer 43b turns on a switch (for example, switch SW1) connected in parallel to the light source in which an open abnormality has occurred (for example, the first light source 10) among the first light source 10, the second light source 20, and the third light source 30. Thereby, the light source in which an open abnormality has occurred (for example, the first light source 10) is turned off, and the other light sources (for example, the second light source 20 and the third light source 30) can continue to be turned on.

[0094] Further, the lighting module 40b includes detection circuits 44 to 46 provided in parallel to each of the first light source 10, the second light source 20, and the third light source 30. Further, the microcomputer 43b detects the light source (for example, the first light source 10) in which an open abnormality has occurred among the first light source 10, the second light source 20, and the third light source 30 based on the outputs from the detection circuits 44 to 46. Thereby, while the signal Sfault can only detect that an open abnormality has occurred in any one of the light sources, when detecting the outputs of the detection circuits 44 to 46, it is possible to detect in which of the light sources an open abnormality has occurred.

[0095] The above embodiments are for facilitating the understanding of the present invention and are not for limiting and interpreting the present invention. Further, the present invention can be changed and improved without departing from its gist, and it goes without saying that equivalents of the present invention are included therein.

Description of Reference Numerals

[0096] 1 Vehicle lamp 2 Battery 10 First light source 11 Light emitting element 20 Second light source 21 Light emitting element 30 Third light source 31 Light emitting element 40a, 40b Lighting module 41 Boost circuit 42 Drive circuit 43a, 43b Microcomputer 44 to 46 Detection circuit 441, 442, 451, 452, 461, 462 Resistor

Claims

1. A lighting module applicable to a luminaire including n (n > 1) light sources connected in series, a boost circuit that boosts a first voltage and outputs a second voltage at a first level, a drive circuit that supplies a predetermined drive current to the n light sources based on the second voltage, and a control circuit that, when the state of the drive circuit becomes abnormal, causes the boost circuit to output the second voltage at a second level higher than the first level, and detects a light source in which an open abnormality has occurred among the n light sources. A lighting module comprising the above.

2. The lighting module according to Claim 1, wherein each of the n light sources includes at least one light-emitting element, and the level difference between the first and second levels is greater than the level difference of the voltage change that occurs across the one light-emitting element when the one light-emitting element has an open abnormality. A lighting module.

3. The lighting module according to Claim 2, comprising n switches connected in parallel to each of the n light sources, wherein the control circuit turns on the switch provided in parallel with the light source in which the open abnormality has occurred. A lighting module.

4. The lighting module according to Claim 3, comprising n voltage detection circuits provided in parallel to each of the n light sources, wherein the control circuit detects a light source in which an open abnormality has occurred based on the outputs from the n voltage detection circuits. A lighting module.

5. The lighting module according to any one of Claims 1 to 4, wherein the luminaire is a vehicle luminaire used in a vehicle. A lighting module.

6. A lighting module applicable to a luminaire including n (n > 1) light sources connected in series, n switches connected in parallel to each of the n light sources, a drive circuit that supplies a predetermined drive current to the n light sources, and a control circuit that controls the on / off of the n switches to turn on or off each of the n light sources, comprising the above, wherein the control circuit when the state of the drive circuit becomes abnormal, turns on at least one of the n switches and detects a light source in which an open abnormality has occurred among the n light sources. A lighting module.

7. The lighting module according to Claim 6, wherein the control circuit when the state of the drive circuit becomes the above abnormality, turns on at least one of the n switches in a predetermined order and detects a light source in which an open abnormality has occurred. A lighting module.

8. The lighting module according to claim 7, wherein the control circuit increases the current value of the drive current in the drive circuit while turning on at least one of the n switches in the predetermined order. Lighting module.

9. The lighting module according to claim 8, wherein the control circuit turns on a switch connected in parallel to a light source in which an open abnormality has occurred among the n light sources. Lighting module.

10. The lighting module according to claim 9, wherein it includes n voltage detection circuits provided in parallel to each of the n light sources, the control circuit detects a light source in which an open abnormality has occurred among the n light sources based on the outputs from the n voltage detection circuits. Lighting module.

11. The lighting module according to any one of claims 6 to 10, wherein the lighting fixture is a vehicle lighting fixture used for a vehicle. Lighting module.

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