Lighting module

Abstract

The invention provides a lighting module capable of detecting an open circuit abnormality of a light source while suppressing heat generation. The lighting module is applied to a lamp provided with n (ngt, 1) light sources connected in series, and is provided with: a booster circuit that boosts a first voltage and outputs a second voltage of a first level; a drive circuit that supplies a predetermined drive current to the n light sources on the basis of the second voltage; and a control circuit that, when the state of the drive circuit becomes abnormal, causes the booster 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.

Description

Technical Field

[0001] The invention relates to a lighting module. Background Art

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

[0003] Prior art literature Patent Literature Patent document 1: Japanese Patent Application Publication No. 2020-87830. Summary of the invention

[0004] Problems to be solved by the invention Incidentally, in consideration of the fact that an open circuit abnormality occurs in any of the multiple light sources, the voltage applied to the multiple light sources by the driving circuit of the lighting module is set to be relatively high. However, when the driving circuit lights up the multiple light sources, if a high voltage is applied to the multiple light sources, the heat (or power consumption) of the lighting module and the multiple light sources increases.

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

[0006] Means used to solve problems The main purpose of the present invention to solve the above-mentioned problem is to provide a lighting module, which is applied to a lamp having n (n>1) light sources connected in series, wherein the lighting module comprises: a boost circuit, which boosts a first voltage and outputs a second voltage of a first level; a drive circuit, which supplies a predetermined drive current to the n light sources based on the second voltage; and a control circuit, which causes the boost circuit to output the second voltage of a second level higher than the first level when the state of the drive circuit becomes abnormal, so as to detect a light source among the n light sources that has an open circuit abnormality.

[0007] Effects of the Invention According to the present invention, it is possible to provide a lighting module capable of detecting an open-circuit abnormality of a light source while suppressing heat generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a block diagram of an example of a vehicle lamp using a lighting module.

[0009] Figure 2 This is a table showing an example of a voltage generated in a light source when an open circuit abnormality occurs in the light source.

[0010] Figure 3This is a table showing an example of the relationship between the lighting pattern and the detection of the open circuit abnormality in the second embodiment.

[0011] Figure 4 This is a diagram showing an example of the operation of the lighting module in the second embodiment.

[0012] Description of Reference Numerals 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; 44~46: detection circuit; 441, 442, 451, 452, 461, 462: resistors. DETAILED DESCRIPTION

[0013] At least the following matters will become clear from the description of this specification and the drawings.

[0014] =====First Embodiment====== <<Structure of vehicle lamp 1>> Figure 1 1 is a diagram showing an example of the configuration of the vehicle lamp 1 using the lighting module 40 a according to the present embodiment.

[0015] The vehicle lamp 1 is a lamp that lights up 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 a lighting module 40a.

[0016] <First Light Source 10> The first light source 10 is, for example, a low beam light source, and is connected between terminal E and terminal F (described later) of the lighting module 40a. The low beam illuminates the vicinity of the vehicle, and the light distribution is determined so as not to cause glare to oncoming vehicles and preceding vehicles, and is mainly used when driving in urban areas.

[0017] 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 LEDs, and other semiconductor light emitting elements such as laser diodes (LDs) and organic EL elements may also be used. In addition, the light emitting element 21 of the second light source 20 and the light emitting element 31 of the third light source 30 described later also use the same element (LED) as the light emitting element 11.

[0018] In addition, Figure 1In the embodiment, for the sake of simplicity, the number of 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 of (for example, six) light-emitting elements 11 are connected in series. In addition, the voltage at both ends of the first light source 10 when it is turned on is set to 12V as a standard value, for example. In addition, the voltage generated at both ends of the first light source 10 by turning on the first light source 10 is set to 15V as a maximum value. In addition, hereinafter, the forward voltage of a light-emitting element is set to 2V, for example. In addition, the "standard value of the voltage at both ends of the light source" refers to the voltage value when the forward voltage of the light-emitting element is a standard value within the range that can be obtained according to manufacturing deviations, temperature characteristics of the light-emitting element, etc., and the "maximum value of the voltage at both ends of the light source" refers to the voltage value when the forward voltage of the light-emitting element is the maximum value within the range that can be obtained according to manufacturing deviations, temperature characteristics of the light-emitting element, etc.

[0019] <Second Light Source 20> The second light source 20 is, for example, a light source for high beam, and is connected between terminal G and terminal H (described later) of the lighting module 40a. In addition, the high beam illuminates a large area in front of the vehicle and far away, and is mainly used when driving at high speed on a road with few oncoming vehicles and vehicles ahead. As described later, in the lighting module 40a, terminal F is connected to terminal G, so the second light source 20 is connected in series with the first light source 10.

[0020] In addition, the second light source 20 includes at least one light emitting element 21. Figure 1 In the embodiment, for simplicity, the number of the 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 of (for example, ten) light emitting elements 21 are connected in series. In addition, the voltage at both ends of the second light source 20 when it is turned on is set to 20 V as a standard value, for example. In addition, the voltage generated at both ends of the second light source 20 by turning on the second light source 20 is set to 25 V as a maximum value, for example.

[0021] <Third Light Source 30> The third light source 30 is, for example, a light source for a position light, and is connected between a terminal I and a terminal J (described later) of the lighting module 40a. In addition, the position light indicates the width of the vehicle, and is also called a vehicle width light, and is provided near the left and right ends of the front of the vehicle. As described later, in the lighting module 40a, the terminal H is connected to the terminal I, and therefore, the third light source 30 is connected in series with the first light source 10 and the second light source 20.

[0022] In addition, the third light source 30 includes at least one light emitting element 31. Figure 1In the embodiment, for simplicity, the number of the 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 of (for example, two) light emitting elements 31 are connected in series. In addition, the voltage at both ends of the third light source 30 when it is turned on is set to, for example, 4 V as a standard value. In addition, the voltage generated at both ends of the third light source 30 by turning on the third light source 30 is set to, for example, 5 V as a maximum value.

[0023] In addition, in this 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 to make each light source emit light, as shown in FIG. Figure 2 As shown, for example, the maximum voltage generated at both ends of the first light source 10, the second light source 20, and the third light source 30 is 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 light up. In addition, the first light source 10, the second light source 20, and the third light source 30 are equivalent to "n light sources".

[0024] In addition, as described above, in order to light up all the light sources while suppressing the heat (or power consumption) in the lighting module 40a and the light sources, the lighting module 40a only needs to apply 45V to the terminal E on the power supply side of the first light source 10. However, in the case where an open circuit abnormality occurs in the light-emitting element of the light source, if the state of applying 45V remains unchanged, the element with the open circuit abnormality cannot be detected by the detection circuit 44 to the detection circuit 46 (described later).

[0025] On the other hand, the lighting module 40a of the present embodiment is a circuit capable of detecting an open circuit abnormality when an open circuit abnormality occurs. In addition, an "open circuit abnormality" refers to an abnormality in which a light emitting element is disconnected and the light emitting element is turned off.

[0026] <Lighting module 40a> The lighting module 40a is applied to the vehicle lamp 1, and is a circuit that lights up the first light source 10, the second light source 20, and the third light source 30 according to the instruction of the control device (not shown, hereinafter also referred to as the vehicle-side ECU) provided on the vehicle side. The lighting module 40a of this embodiment includes a boost circuit 41, a drive circuit 42, a microcomputer 43a, a detection circuit (DET) 44 to a detection circuit 46, a switch SW1, a switch SW2, a switch SW3, and terminals A to J. In addition, the lighting module 40a is a module in which the above-mentioned circuits and terminals are mounted on a substrate CB.

[0027] In addition, in the present embodiment, the boost circuit 41, the drive circuit 42, and the microcomputer 43a of the lighting module 40a are mounted on one substrate CB, but the present invention is not limited thereto. For example, the lighting module may be a module including a substrate on which the boost circuit 41, the drive circuit 42, etc. are mounted and a substrate on which the microcomputer 43a is mounted. In addition, 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.

[0028] A boost circuit 41 , a drive circuit 42 , a microcomputer 43 a , detection circuits 44 to 46 , a switch SW1 , a switch SW2 , a switch SW3 , and terminals A to J are provided on the substrate CB.

[0029] The 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 .

[0030] The terminal B is connected to the negative electrode of the battery 2 , and a ground level voltage is applied from the battery 2 .

[0031] The terminal C is a terminal to which a control signal S1 is input from the vehicle-side ECU. The control signal S1 is a signal that instructs the first light source 10 , the second light source 20 , and the third light source 30 to turn on or off.

[0032] The terminal D is a terminal for outputting a detection signal S2 to the vehicle-side ECU. The detection signal S2 is a signal indicating that an abnormality is detected in at least one of the first light source 10 , the second light source 20 , and the third light source 30 .

[0033] The terminal E and the terminal F are terminals for connecting the first light source 10. In addition, the output voltage Vout of the drive circuit 42 is applied to the terminal E.

[0034] The terminal G and the terminal H are terminals for connecting to the second light source 20. In addition, the terminal G is connected to the terminal F, and the terminal H is connected to the terminal I in the lighting module 40a.

[0035] The terminal I and the terminal J are terminals for connecting to the third light source 30. In addition, the terminal I is connected to the terminal H, and the terminal J is connected to the terminal B in the lighting module 40a.

[0036] The switch SW1 is a switch provided between the terminal E and the terminal F (in other words, connected in parallel with the first light source 10). When the switch SW1 is turned on (conductive), a path is formed that bypasses the first light source 10 and supplies current to the second light source 20. As a result, current is not supplied to the first light source 10, so the first light source 10 is not lit and is in an extinguished state. On the other hand, when the switch SW1 is turned off (non-conductive), current is supplied to the first light source 10, and the first light source 10 becomes in a lit state.

[0037] The switch SW2 is a switch provided between the terminal G and the terminal H (in other words, connected in parallel with the second light source 20). When the switch SW2 is turned on, a path bypassing the second light source 20 is formed. As a result, no current is supplied to the second light source 20, so the second light source 20 is not lit but is in an off state. On the other hand, when the switch SW2 is turned off, current is supplied to the second light source 20, and the second light source 20 becomes in a lit state.

[0038] The switch SW3 is a switch provided between the terminal I and the terminal J (in other words, connected in parallel with the third light source 30). When the switch SW3 is turned on, a path bypassing the third light source 30 is formed. As a result, no current is supplied to the third light source 30, so the third light source 30 is not lit but is in an off state. On the other hand, when the switch SW3 is turned off, current is supplied to the third light source 30, and the third light source 30 becomes in a lit state. In addition, the switches SW1 to SW3 are equivalent to "n switches".

[0039] 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 of the voltage level LV1, and outputs the voltage V2 of the voltage level LV2 based on the control signal Scnt1 from the microcomputer 43a (described later). In addition, the voltage level LV2 is higher than the voltage level LV1. In addition, the voltage V1 is equivalent to the "first voltage", the voltage V2 is equivalent to the "second voltage", the voltage level LV1 is equivalent to the "first level", and the voltage level LV2 is equivalent to the "second level".

[0040] Incidentally, in the present embodiment, when the driving 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 circuit abnormality occurs in one of the light-emitting elements, the difference in voltage level between the two ends of the light-emitting element in normal state and when the open circuit abnormality occurs is greater than the forward voltage of 2 V. In addition, the "difference in voltage level between the two ends of the light-emitting element" is the difference in voltage level between the cathode and the anode of the light-emitting element.

[0041] The state of the driving circuit 42 becomes abnormal, and the level difference before and after the output voltage is increased in the boost circuit 41 (for example, 12V) is larger than the level difference (for example, 10V) of the voltage change generated at both ends of a light-emitting element when a light-emitting element becomes an open circuit abnormality. Details will be described later.

[0042] Thus, the lighting module 40 a can detect an open-circuit abnormality of the light source while suppressing heat generation (or power consumption) in normal times.

[0043] The drive circuit 42 is a circuit (constant current circuit) that outputs a predetermined drive current Iout for lighting 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., the output of the drive circuit 42 is short-circuited or open-circuited), the drive circuit 42 outputs a signal Sfault. The drive circuit 42 is, for example, composed of a step-down switching regulator (DC-DC converter). In addition, the drive circuit 42 is not limited to a switching regulator, and may also be, for example, a linear regulator.

[0044] The output short circuit of the drive circuit 42 refers to a state where a node to which the output voltage Vout is applied is connected to the ground, for example. The output open circuit of the drive circuit 42 refers to a state where the current value of the drive current Iout is sufficiently smaller than a predetermined current value.

[0045] The microcomputer 43a is a circuit that controls the operation of the vehicle lamp 1, and will be described in detail 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.

[0046] Specifically, the microcomputer 43a detects the signals Sv1, Sv2, and Sv3 from the 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.

[0047] In addition, the microcomputer 43a outputs a signal Scnt1 to cause the boost circuit 41 to output a voltage V2 of a voltage level LV2. The signal Siup will be described later.

[0048] The microcomputer 43a is realized as a hardware configuration by components and circuits represented by a CPU and a memory of a computer, and as a software configuration by a computer program, etc. The microcomputer 43a corresponds to a "control circuit".

[0049] The detection circuit (DET) 44 includes, for example, a resistor 441 and a resistor 442, and is disposed between the terminal E and the terminal F (in other words, connected in parallel with the first light source 10). It is a voltage divider circuit that detects the voltage between the terminal E and the terminal F, and outputs a signal Sv1 corresponding to the voltage between the terminal E and the terminal F. Specifically, when the first light source 10 is normally lit, 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 an overvoltage. In addition, when the first light source 10 is short-circuited, the detection circuit 44 outputs a signal Sv1 indicating a short circuit.

[0050] The detection circuit 45 includes, for example, a resistor 451 and a resistor 452, and is disposed between the terminal G and the terminal H (in other words, connected in parallel with the second light source 20). The detection circuit 45 is a voltage divider circuit that detects the voltage between the terminal G and the terminal H, and outputs a signal Sv2 corresponding to the voltage between the terminal G and the terminal H. Specifically, when the second light source 20 is normally lit, 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 an overvoltage. In addition, when the second light source 20 is short-circuited, the detection circuit 45 outputs a signal Sv2 indicating a short circuit.

[0051] The detection circuit 46 includes, for example, a resistor 461 and a resistor 462, and is disposed between the terminal I and the terminal J (in other words, connected in parallel with the third light source 30). The detection circuit 46 is a voltage divider circuit that detects the voltage between the terminal I and the terminal J, and outputs a signal Sv3 corresponding to the voltage between the terminal I and the terminal J. Specifically, when the third light source 30 is normally lit, 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 an overvoltage. In addition, when the third light source 30 is short-circuited, the detection circuit 46 outputs a signal Sv3 indicating a short circuit.

[0052] In addition, as detection circuits 44 to 46, for example, a voltage divider circuit has been described, but a voltage detector (i.e., a reset IC) may also be used, which outputs a signal indicating that an overvoltage has been applied when it detects that the applied voltage of each light source is higher than normal. In this case, a circuit may also be provided that converts the voltage of the signal output by the voltage detector into a voltage that can be processed by the microcomputer 43a. Furthermore, the following circuit may also be used: using a comparator, an overvoltage is detected, the level is converted into a voltage that can be processed by the microcomputer 43a, and a signal indicating that an overvoltage has been applied (for example, signal Sv1) is output. In addition, for example, the voltage applied to the detection circuit 44 may also be level-converted, and the level is converted into a voltage that can be processed by the microcomputer 43a as the signal Sv1. In addition, detection circuits 44 to 46 are equivalent to "n voltage detection circuits".

[0053] ===Operation of Microcomputer 43a=== Below, refer to Figure 2 , how the microcomputer 43a detects the open circuit anomaly of the first light source 10, the second light source 20, and the third light source 30 is described. In addition, in the present embodiment, the open circuit anomaly detection threshold of each of the first light source 10, the second light source 20, and the third light source 30 is set to a value obtained by adding a predetermined voltage Vdelta to the voltage generated at both ends of the light source in normal circumstances. In addition, in the present embodiment, the voltage Vdelta is, for example, 10V, but varies according to the temperature characteristics of the light-emitting element included in the light source, manufacturing deviations, etc.

[0054] <<About normal actions>> First, the normal operation of the lighting module 40a is described. The boost circuit 41 boosts the voltage V1 and outputs a voltage V2 of a voltage level LV1. Here, the voltage level LV1 is a voltage level (eg, 45V) that can light up the first light source 10, the second light source 20, and the third light source 30.

[0055] Then, the drive circuit 42 is supplied with the voltage V2 from the boost circuit 41, and supplies the output voltage Vout (for example, Figure 2 As shown, 45V), and supply driving current Iout. Thus, the lighting module 40a can light up the three light sources.

[0056] <<About the operation when the first light source 10 has an open circuit abnormality>> Here, the case where an open circuit abnormality occurs in the first light source 10 is described. When an open circuit abnormality occurs in the first light source 10, the light emitting element 11 of the first light source 10 becomes high resistance and the drive current Iout decreases, so the drive circuit 42 outputs a signal Sfault indicating an abnormality to the microcomputer 43a.

[0057] When the microcomputer 43a receives the signal Sfault, it outputs a signal Scnt1 for causing the boost circuit 41 to output the voltage V2 at the voltage level LV2 in order to detect in which light source the open circuit abnormality has occurred.

[0058] The boost circuit 41 receives the signal Scnt1 and outputs a voltage V2 of a voltage level LV2 (eg, 57V). Figure 2 As shown, voltage is applied to the first light source 10, the second light source 20, and the third light source 30. At this time, if the voltage level LV2 is increased to a voltage level higher than the voltage level LV1 by a voltage Vdelta or more, for example, an open circuit abnormality of the first light source 10 can be detected. In addition, Figure 2 The voltage values ​​shown are for convenience of explanation, and since the driving current Iout from the driving circuit 42 is reduced, a voltage lower than the normal voltage is applied to the second light source 20 and the third light source 30. In addition, when an open circuit abnormality occurs in the second light source 20 and the third light source 30, the voltage applied to the normal light source is also lower than the normal voltage.

[0059] As described above, an open circuit abnormality occurs in the first light source 10, and thus, an open circuit abnormality detection threshold (such as Figure 2 In this case, the detection circuit 44 outputs a signal Sv1 indicating an overvoltage.

[0060] Then, the microcomputer 43a detects the occurrence of an open circuit abnormality in the first light source 10 based on the signals Sv1, Sv2, and Sv3 from the detection circuits 44 to 46. After that, the microcomputer 43a turns on the switch (i.e., switch SW1) provided in parallel with the light source having the open circuit abnormality, so that the light source having the open circuit abnormality (i.e., the first light source 10) is extinguished. Thus, the light sources other than the first light source 10 (e.g., the second light source 20 and the third light source 30) continue to light up. Then, the microcomputer 43a outputs a signal Scnt1 so that the boost circuit 41 outputs a voltage V2 of a voltage level LV1. Thus, the heating of the lighting module 40a can be suppressed.

[0061] <<About Operation When Open Circuit Abnormality Occurs in Second Light Source 20>> Here, a case where an open circuit abnormality occurs in the second light source 20 will be described. The operation until the boost circuit 41 receives the signal Scnt1 and outputs the voltage V2 of the voltage level LV2 (eg, 57 V) is as described above.

[0062] Then, if Figure 2As shown, voltage is applied to the first light source 10, the second light source 20, and the third light source 30. Thus, an open circuit abnormality detection threshold (such as Figure 2 As shown, for example, a voltage of 35 V or more is detected. In this case, the detection circuit 45 outputs a signal Sv2 indicating an overvoltage.

[0063] Then, the microcomputer 43a detects the occurrence of an open circuit abnormality in the second light source 20 based on the signals Sv1, Sv2, and Sv3 from the detection circuits 44 to 46. After that, the microcomputer 43a turns on the switch (i.e., switch SW2) provided in parallel with the light source having the open circuit abnormality, so that the light source having the open circuit abnormality (i.e., the second light source 20) is extinguished. Thus, the light sources other than the second light source 20 (e.g., the first light source 10 and the third light source 30) continue to light up. Then, the microcomputer 43a outputs a signal Scnt1 so that the boost circuit 41 outputs a voltage V2 of a voltage level LV1. Thus, the heating of the lighting module 40a can be suppressed.

[0064] <<About Operation When Open Circuit Abnormality Occurs in the Third Light Source 30>> Here, a case where an open circuit abnormality occurs in the third light source 30 will be described. Note that the operation until the boost circuit 41 receives the signal Scnt1 and outputs the voltage V2 of the voltage level LV2 (eg, 57 V) is as described above.

[0065] Then, if Figure 2 As shown, voltage is applied to the first light source 10, the second light source 20, and the third light source 30. Thus, an open circuit abnormality detection threshold (such as Figure 2 As shown, for example, a voltage of 15 V or more is detected. In this case, the detection circuit 46 outputs a signal Sv3 indicating an overvoltage.

[0066] Then, the microcomputer 43a detects the occurrence of an open circuit abnormality in the third light source 30 based on the signals Sv1, Sv2, and Sv3 from the detection circuits 44 to 46. After that, the microcomputer 43a turns on the switch (i.e., switch SW3) provided in parallel with the light source having the open circuit abnormality, so that the light source having the open circuit abnormality (i.e., the third light source 30) is extinguished. Thus, the light sources other than the third light source 30 (e.g., the first light source 10 and the second light source 20) continue to light up. Then, the microcomputer 43a outputs a signal Scnt1 so that the boost circuit 41 outputs a voltage V2 of a voltage level LV1. Thus, the heating of the lighting module 40a can be suppressed.

[0067] Thus, it is possible to provide a lighting module capable of detecting an open-circuit abnormality of a light source while suppressing heat generation.

[0068] =====Second Embodiment====== Incidentally, if an open circuit abnormality occurs in a light emitting element, the voltage between both ends of the light source including the light emitting element having the open circuit abnormality increases. Therefore, in the first embodiment, in order to detect the voltage between both ends, the output voltage Vout of the driving circuit 42 is increased compared to normal.

[0069] However, instead of further increasing the output voltage Vout of the drive circuit 42 , a voltage capable of detecting the open-circuit abnormality may be applied to the light-emitting element in which the open-circuit abnormality has occurred.

[0070] In the second embodiment, when the state of the driving circuit 42 becomes abnormal, any one of the switches SW1, SW2, and SW3 provided in parallel is turned on to turn off any one of the first light source 10, the second light source 20, and the third light source 30.

[0071] Thus, the output voltage Vout of, for example, 45V from the drive circuit 42 is applied not to the first light source 10, the second light source 20, and the third light source 30, but to two of them. As a result, the voltage between the two ends of the light source that is operating in a lighting manner (i.e., the light source with the switches SW1 to SW3 connected in parallel disconnected) can be increased. Therefore, in the case of the second embodiment, the open circuit abnormality can be detected without increasing the output voltage Vout of the drive circuit 42 from, for example, 45V to 57V.

[0072] The lighting module 40b as the lighting module of the second embodiment includes a boost circuit 41, a drive circuit 42, a microcomputer 43b, a switch SW1, a switch SW2, a switch SW3, and terminals A to J. In addition, except for the microcomputer 43b, it is the same as the lighting module 40a, so the detailed description is omitted. In addition, as in the case of the first embodiment, the microcomputer 43b and other circuits can be mounted on different substrates, and these substrates are connected to form a lighting module.

[0073] A second embodiment using a microcomputer 43b for detecting an open circuit abnormality of the first light source 10, the second light source 20, or the third light source 30 without causing the booster circuit 41 to output the voltage V2 of the voltage level LV2 will be described below. The microcomputer 43b corresponds to a "control circuit."

[0074] <<Detection of Open Circuit Abnormality in Second Embodiment>> The boost circuit 41 boosts the voltage V1 and outputs a voltage V2 of a voltage level (for example, 45 V) capable of lighting the first light source 10 , the second light source 20 , and the third light source 30 .

[0075] Then, the drive circuit 42 is supplied with the voltage V2 from the booster circuit 41, and supplies a predetermined drive current Iout. At this time, there is a possibility that the voltage between the terminals connected to the light source in which the open circuit abnormality has occurred increases.

[0076] Furthermore, the drive circuit 42 supplies the drive current Iout, but if the output voltage Vout is an overvoltage, the drive circuit 42 outputs a signal Sfault indicating an abnormality to the microcomputer 43b.

[0077] When receiving the signal Sfault, the microcomputer 43b turns on the switches SW1 to SW3 one by one in a predetermined mode, and outputs a signal Siup to cause the drive circuit 42 to increase the current value of the drive current Iout supplied to the lit light source. Specifically, Figure 3 As shown in FIG. 1 , mode Pa is a mode in which switch SW1 is turned on among switches SW1 to SW3, and mode Pb is a mode in which switch SW2 is turned on among switches SW1 to SW3. Furthermore, mode Pc is a mode in which switch SW3 is turned on among switches SW1 to SW3. In addition, mode Pall is a mode in which all switches SW1 to SW3 are turned off. In addition, descriptions other than mode Pa, mode Pb, mode Pc, and mode Pall will be described when the operation of the lighting module 40b is described.

[0078] <<Operation of Microcomputer 43b>> Below, refer to Figure 4 The operation of the microcomputer 43b in the second embodiment will be described. Figure 4 In the description, it is assumed that an open circuit abnormality occurs in the first light source 10. In addition, outside the period T for detecting the open circuit abnormality, in order to light up 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 the PWM signal. In addition, the off duty ratio of the switches SW1 to SW3 is determined to be the average current required to flow when each light source is lit. Figure 4 The total voltage in is recorded assuming that an open circuit abnormality occurs in the first light source 10 .

[0079] At time t0, the microcomputer 43b turns on the switch SW1 to turn off the first light source 10. On the other hand, the switches SW2 and SW3 are turned off. Figure 3 As shown, the voltage between the two ends of the first light source 10 is 0V, the voltage between the two ends of the second light source 20 is 25V, and the voltage between the two ends of the third light source 30 is 5V. Figure 3As shown in FIG. 1 , the total voltage generated at both ends of the first light source 10, the second light source 20, and the third light source 30 is 30 V, which is lower than the voltage Vout of 45 V. However, the switch SW1 is turned on and the first light source 10 is turned off. Therefore, in the case of mode Pa, it is impossible to detect that an open circuit abnormality has occurred in the first light source 10. That is, Figure 3 As shown, open circuit abnormality cannot be detected.

[0080] At time t1, the microcomputer 43b turns off the switch SW1. After that, all switches SW1 to SW3 are turned off, and the total voltage becomes 55V. Figure 3 As shown, it is higher than the voltage Vout. Therefore, in mode Pall, Figure 3 As shown, open circuit abnormality cannot be detected.

[0081] At time t2, the microcomputer 43b turns on the switch SW2 to turn off the second light source 20. On the other hand, the switches SW1 and SW3 are turned off. Figure 3 As shown in FIG. 1 , the voltage between the two ends of the first light source 10 becomes 25V, the voltage between the two ends of the second light source 20 becomes 0V, and the voltage between the two ends of the third light source 30 becomes 5V. Figure 3 As shown in FIG. 1 , the total voltage is 30 V, which is lower than the voltage Vout. Therefore, the open circuit abnormality occurring in the first light source 10 can be detected. Figure 3 As shown, open circuit abnormality can be detected.

[0082] At time t3, the microcomputer 43b turns off the switch SW2 and switches to the mode Pall.

[0083] At time t4, the microcomputer 43b turns on the switch SW3 to turn off the third light source 30. On the other hand, the switches SW1 and SW2 are turned off. Figure 3 As shown in FIG. 1 , the voltage between the two ends of the first light source 10 becomes 25V, the voltage between the two ends of the second light source 20 becomes 25V, and the voltage between the two ends of the third light source 30 becomes 0V. Figure 3 As shown in FIG. 1 , the total voltage becomes 50V, which is higher than the voltage Vout. Therefore, the open circuit abnormality of the first light source 10 cannot be detected. Figure 3 As shown, open circuit abnormality cannot be detected.

[0084] At time t5, the microcomputer 43b turns off the switch SW3 and switches to the mode Pall.

[0085] After time t6, the operation from time t0 to time t6 is repeated (ie, cycle T) until it is confirmed that the detection of the open circuit abnormality occurring in the first light source 10 is not a false detection. This can suppress false detection of the open circuit abnormality.

[0086] The above description assumes that an open circuit abnormality occurs in the first light source 10, and explains the operation of the microcomputer 43b. However, the same is true for the case where an open circuit abnormality occurs in the light emitting elements of the second light source 20 and the third light source 30. For example, when an open circuit abnormality occurs in the second light source 20, the microcomputer 43b can be operated. Figure 3 In the case of an open circuit abnormality in the third light source 30, the open circuit abnormality can be detected in the mode Pa. Figure 3 An open circuit abnormality is detected in mode Pa or mode Pb.

[0087] Thus, it is possible to provide a lighting module capable of detecting an open-circuit abnormality of a light source while suppressing heat generation.

[0088] In the second embodiment, if the switches SW1 to SW3 are turned on as described above and the three light sources are turned off in sequence, the brightness of the three light sources becomes dim. Therefore, the microcomputer 43b increases the drive current Iout of the drive circuit 42 so that the brightness of the three light sources is approximately equal to the normal brightness.

[0089] Therefore, in the second embodiment, even when the open circuit abnormality detection process is executed, the brightness of the light source to be lit can be made substantially equal to the brightness when the three light sources are normally lit.

[0090] =====Summary===== The vehicle lamp 1 of the present embodiment has been described above. The lighting module 40a of the vehicle lamp 1 includes: a boost circuit 41 that boosts the voltage V1 and outputs a voltage V2 of 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 a microcomputer 43a that, when the state of the drive circuit 42 becomes abnormal, causes the boost circuit 41 to output a voltage V2 of a voltage level LV2 higher than the voltage level LV1, and detects a light source having an open circuit abnormality among the plurality of light sources. Thus, a lighting module that can detect an open circuit abnormality of a light source while suppressing heat generation can be provided.

[0091] In addition, the first light source 10, the second light source 20, and the third light source 30 each include at least one light emitting element, and the level difference between the voltage level LV1 and the voltage level LV2 (for example, 12 V) is greater than the level difference of the voltage change generated at both ends of one light emitting element when one light emitting element becomes an open circuit abnormality (for example, 10 V). Thus, a voltage of an amount capable of detecting the open circuit abnormality can be applied to the light source (for example, the first light source 10) in which the open circuit abnormality occurs in the light emitting element.

[0092] In addition, the lighting module 40a includes switches SW1 to SW3 respectively connected in parallel with 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) having an open circuit abnormality. Thus, the light source (for example, the first light source 10) having an open circuit abnormality is extinguished, and the other light sources (for example, the second light source 20 and the third light source 30) continue to light up.

[0093] In addition, there are detection circuits 44 to 46 respectively arranged in parallel with the first light source 10, the second light source 20, and the third light source 30, and the microcomputer 43a detects the light source (for example, the first light source 10) that has an open circuit abnormality based on the output from the detection circuits 44 to 46. Thus, in the signal Sfault, only the fact that any one of the light sources has an open circuit abnormality can be detected, and on the contrary, if the output of the detection circuits 44 to 46 is detected, it can be detected which of the light sources has an open circuit abnormality.

[0094] In addition, the lighting module 40b of the vehicle lamp 1 includes: switches SW1 to SW3, which are respectively connected in parallel to the first light source 10, the second light source 20, and the third light source 30; a driving circuit 42, which supplies a predetermined driving current Iout to the light source; and a microcomputer 43b, which controls the on and off of the switches SW1 to SW3 to light up or extinguish the light sources. In addition, if the state of the driving circuit 42 becomes abnormal, the microcomputer 43b turns on at least one of the switches SW1 to SW3 to detect the light source with an open circuit abnormality. Thus, a lighting module that can detect an open circuit abnormality of a light source while suppressing heat generation can be provided.

[0095] In addition, when the state of the driving circuit 42 becomes abnormal, the microcomputer 43b turns on the switches SW1 to SW3 at least one by one in a predetermined order to detect the light source with an open circuit abnormality. Thus, even if the output voltage Vout of the driving circuit 42 is not increased, the light source with an open circuit abnormality can be detected.

[0096] In addition, the microcomputer 43b causes the drive circuit 42 to increase the current value of the drive current Iout during the period when the switches SW1 to SW3 are turned on at least one by one in a predetermined order (i.e., during the period T). Thus, even when the detection process of the open circuit abnormality is performed, the brightness of the light source that is lit can be made substantially equal to the brightness when the three light sources are normally lit.

[0097] In addition, the microcomputer 43b turns on the switch (e.g., switch SW1) connected in parallel with the light source (e.g., the first light source 10) that has the open circuit abnormality among the first light source 10, the second light source 20, and the third light source 30. Thus, the light source (e.g., the first light source 10) that has the open circuit abnormality is extinguished, and the other light sources (e.g., the second light source 20, the third light source 30) continue to light up.

[0098] In addition, the lighting module 40b includes detection circuits 44 to 46 respectively provided in parallel with the first light source 10, the second light source 20, and the third light source 30. In addition, the microcomputer 43b detects the light source (for example, the first light source 10) that has an open circuit abnormality among the first light source 10, the second light source 20, and the third light source 30 based on the output from the detection circuits 44 to 46. Thus, in the signal Sfault, only the fact that any one of the light sources has an open circuit abnormality can be detected, whereas, if the output of the detection circuits 44 to 46 is detected, it can be detected which of the light sources has an open circuit abnormality.

[0099] The above-mentioned embodiments are for easy understanding of the present invention and are not intended to limit the interpretation of the present invention. In addition, the present invention can be changed and improved without departing from the gist thereof, and the present invention naturally includes equivalents thereof.

Claims

1. A lighting module, which is applied to a lamp having n (n>1) light sources connected in series, wherein: The lighting module has: a boost circuit, which boosts the first voltage and outputs a second voltage of a first level; a driving circuit configured to supply a predetermined driving current to the n light sources based on the second voltage; as well as The control circuit causes the boost circuit to output the second voltage of a second level higher than the first level to detect a light source having an open circuit abnormality among the n light sources when the state of the drive circuit becomes abnormal.

2. The lighting module according to claim 1, wherein: The n light sources each include at least one light-emitting element, A level difference between the first level and the second level is greater than a level difference of a voltage change generated across both ends of the one light emitting element when the one light emitting element becomes an open circuit abnormality.

3. The lighting module according to claim 2, wherein: The lighting module includes n switches connected in parallel to the n light sources respectively. The control circuit turns on a switch that is connected in parallel with the light source that has an open circuit anomaly.

4. The lighting module according to claim 3, wherein: The lighting module comprises n voltage detection circuits respectively arranged in parallel with the n light sources. The control circuit detects a light source in which an open circuit abnormality has occurred based on outputs from the n voltage detection circuits.

5. The lighting module according to any one of claims 1 to 4, wherein: The lamp is a vehicle lamp for a vehicle.

6. A lighting module, which is applied to a lamp having n (n>1) light sources connected in series, wherein: The lighting module has: n switches, which are respectively connected in parallel with the n light sources; A driving circuit that supplies a predetermined driving current to the n light sources; as well as A control circuit controls the on and off of the n switches to light up or turn off the n light sources respectively. When the state of the driving circuit becomes abnormal, the control circuit turns on at least one of the n switches to detect a light source having an open circuit abnormality among the n light sources.

7. The lighting module according to claim 6, wherein: When the state of the drive circuit becomes abnormal, the control circuit turns on the n switches at least one by one in a predetermined order to detect the light source having an open circuit abnormality.

8. The lighting module according to claim 7, wherein: The control circuit causes the drive circuit to increase the current value of the drive current while the control circuit turns on the n switches at least one by one in the predetermined order.

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

10. The lighting module according to claim 9, wherein: The lighting module comprises n voltage detection circuits respectively arranged in parallel with the n light sources. The control circuit detects a light source having an open circuit abnormality among the n light sources based on outputs from the n voltage detection circuits.

11. The lighting module according to any one of claims 6 to 10, wherein: The lamp is a vehicle lamp for a vehicle.

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