VEHICLE FRONT LIGHTING DEVICE AND INTERRUPTION PROCEDURES

Abstract

Vehicle front lighting device (100) for illuminating an area in front of a vehicle (1) using several lighting devices (LED 1 to LED 12) in a divided manner, wherein the vehicle front lighting device comprises: a lighting device array (10) in which the lighting devices are connected in series; several bypass circuits (21) arranged for the respective lighting devices and allowing a current flowing through the lighting devices to bypass the lighting devices; several switching elements (SW1 to SW12) that are arranged for the respective bypass circuits to open and close the bypass circuits; a lighting control unit (22) which controls a lighting mode of the lighting device array by bringing the switching elements corresponding to the lighting devices to be switched on into an open state and bringing the switching elements corresponding to the lighting devices to be switched off into a closed state; a current measurement unit (23) that measures the value of a current flowing through the lighting device array; a voltage value control unit (24) which applies a voltage to the lighting device array and controls a value of the voltage to be applied in order to cause the value of the current flowing through the lighting device array to reach a predetermined setpoint current value; a change magnitude procurement unit (25) that procures the number of switching elements that are in the open state and the value of the controlled voltage each time a predetermined detection condition is met, and a magnitude of change relative to the number of switching elements last detected, and a magnitude of change relative to a value of the voltage last detected; and an interruption detection unit (26) that determines whether the magnitude of the change in the number of switching elements matches the magnitude of the change in the value of the voltage and determines that an interruption has occurred in any of the bypass circuits if it does not match.

Description

Cross-reference to the relevant application

[0001] This application is based on Japanese Patent Application No. 2017-247085 filed on December 22, 2017, the disclosure of which is hereby incorporated by reference. Technical area

[0002] The present invention relates to a vehicle front light device and an open circuit detection method. State of the art

[0003] For a front lighting device mounted on a subject vehicle, it is desirable to be able to illuminate light with high luminance over a long distance and in a wide area to enable a driver of the subject vehicle to perceive a situation at the long distance. To prevent the lighting from causing a dazzling sensation (so-called glare) to a driver of an oncoming vehicle due to the high luminance, it is desirable to be able to reduce the luminance of the light illuminating the area where the oncoming vehicle is present.

[0004] Therefore, a technique has been proposed in which a plurality of lighting devices are mounted for illuminating a front side of the vehicle, and the respective lighting devices are used to illuminate an area in front of the vehicle collectively or in a divided manner (Patent Literature 1).

[0005] With the above technique, when an oncoming vehicle, pedestrian, or the like is absent, the driver of the subject vehicle can easily detect the distant situation by irradiating high-brightness light at a distance and in a wide range. On the other hand, when an oncoming vehicle, pedestrian, or the like is detected, a situation in which the driver of the oncoming vehicle, pedestrian, or the like feels dazzling can be avoided by reducing the brightness of the illuminating device in charge of the area where the oncoming vehicle, pedestrian, or the like exists, or by turning off the illuminating device.

[0006] Furthermore, in the above-described technique, the number of lighting devices mounted on the vehicle is gradually increased. This is because, as the number of mounted lighting devices increases, the area where illumination is performed by an individual lighting device in a divided manner becomes smaller, and therefore, a situation can be prevented in which illumination is dimmed in an area where the oncoming vehicle is not present, for example, when the oncoming vehicle is detected and the brightness of the lighting device is reduced or turned off. Alternatively, as the number of lighting devices is increased, the area in front of the vehicle is divided into smaller areas, so that the distribution of brightness illuminating the front can be brought closer to a suitable distribution. State of the art literaturePatent literature

[0007] PTL 1: JP 2008 - 37 240 A Summary

[0008] However, as the number of lighting devices mounted on the vehicle increases, the number of wires or cables or wiring for controlling the lighting devices also increases, making it difficult to detect whether there is an open circuit in a cable or wiring.

[0009] It is an object of the present invention to provide a vehicle front device and a disconnection detection method capable of detecting the presence or absence of a disconnection of a wire or wiring for driving lighting devices even when a plurality of lighting devices are mounted for collectively illuminating a front portion of the vehicle.

[0010] A vehicle front lighting device according to one aspect of the present invention is for illuminating an area in front of a vehicle using a plurality of lighting devices in a divided manner, and includes: a lighting device array in which the lighting devices are connected in series; a plurality of bypass circuits arranged for the respective lighting devices and allowing a current flowing through the lighting devices to bypass the lighting devices; a plurality of switching elements arranged for the respective bypass circuits for opening and closing the bypass circuits; a lighting control unit; a current value detection unit; a voltage value control unit; a change amount acquisition unit; and an open-circuit determination unit.The lighting control unit controls a lighting mode of the lighting device array by opening the switching elements corresponding to the lighting devices to be turned on and closing the switching elements corresponding to the lighting devices to be turned off. The current value detection unit detects a current flowing through the lighting device array. The voltage value control unit applies a voltage to the lighting device array and controls the applied voltage to cause the current flowing through the lighting device array to reach a predetermined target current value.The change amount acquisition unit detects the number of switching elements brought into the open state and the controlled voltage value each time a predetermined detection condition is met, and acquires a change amount from the number of switching elements detected last time and a change amount from the voltage value detected last time. The open-circuit determination unit determines whether the change amount in the number of switching elements matches the change amount in the voltage value, and determines that an open-circuit has occurred in any of the bypass circuits if it does not match.

[0011] An open-circuit detection method according to another aspect of the present invention is used in a vehicle front lighting device that illuminates an area in front of a vehicle using a lighting device array in which a plurality of lighting devices are connected in series, to detect whether an open circuit has occurred in wiring for driving the lighting devices. The vehicle front lighting device includes: a plurality of bypass circuits arranged for the respective lighting devices and allowing a current flowing through the lighting devices to bypass the lighting devices; a plurality of switching elements arranged for the respective bypass circuits for opening and closing the bypass circuits;and a lighting control unit that controls a lighting mode of the lighting device array by bringing the switching elements corresponding to the lighting devices to be turned on into an open state and bringing the switching elements corresponding to the lighting devices to be turned off into a closed state. The open-circuit detection method includes: applying a voltage to the lighting device array, detecting a value of a current flowing through the lighting device array, and controlling a value of the voltage applied to the lighting device array to cause the value of the current flowing through the lighting device array to reach a predetermined target current value;Detecting the number of switching elements brought into the open state each time a predetermined detection condition is met, and obtaining a magnitude of change from the number of switching elements detected last time; detecting a value of the voltage applied to the lighting device array each time the detection condition is met, and obtaining a magnitude of change from the voltage value detected last time; and determining whether the magnitude of change in the number of switching elements matches the magnitude of change in the voltage value, and determining that an open circuit has occurred in any of the bypass circuits if it does not match.

[0012] According to the vehicle front lighting device and the open circuit detection method, it is possible to determine whether there is a open circuit according to whether the amount of change in the number of lighting devices to be turned on matches the amount of change in the value of the applied voltage, and therefore, even when the area in front of the vehicle is illuminated using a plurality of lighting devices, it is possible to easily detect whether there is a open circuit in the wiring for driving the lighting devices. Short description of the drawings

[0013] The above and other objects, features, and advantages of the present invention will become apparent from the following detailed description with reference to the accompanying drawings. Fig. 1A is a diagram showing a vehicle on which a vehicle front lamp device according to an embodiment of the present invention is mounted; Fig. 1B is an example diagram showing the vehicle front lighting device mounted on the vehicle; Fig. 2 is a block diagram showing an internal structure of the vehicle front light device; Fig. 3A is an example diagram of an operation of the vehicle front lighting device for simultaneously illuminating a plurality of LEDs of an LED array; Fig. 3B is an example diagram of an operation of the vehicle front lighting device for individually illuminating the LEDs of the LED array; Fig. 4 is an example diagram showing a method for changing the luminance of the LEDs by the vehicle front lighting device; Fig. 5 is an example diagram illustrating a state in which the vehicle front lighting device illuminates an area in front of the vehicle by lighting the LEDs of the LED array at the same brightness; Fig. 6A is a diagram showing timings of turning on and off the LEDs determined according to a luminous distribution pattern by the vehicle front lighting device; Fig. 6B is a diagram showing a state in which the number of illuminated LEDs of the vehicle front light device changes with time; Fig. 7A is an example diagram showing a condition where no break occurs in the bypass wiring; Fig. 7B is an example diagram showing an example effect of interrupting the bypass wiring on the operation of lighting the LEDs of the LED array; Fig. 8A is an example diagram showing another example effect of interrupting the bypass wiring on the operation of lighting the LEDs of the LED array; Fig. 8B is an example diagram showing another example effect of interrupting the bypass wiring on the operation of lighting the LEDs of the LED array; Fig. 9A is an example diagram showing the effect of interrupting the bypass wiring on the operation of the illumination of the LEDs of the LED array; Fig. 9B is an example diagram showing the effect of interrupting the bypass wiring on the number of illuminated LEDs of the vehicle front lighting device; Fig. 10A is an example view of a principle for detecting, by the vehicle front lamp device, whether there is a break in the bypass wiring; Fig. 10B is an example view of a principle for detecting, by the vehicle front lamp device, whether there is a break in the bypass wiring; Fig. 10C is an example diagram of a principle for detecting, by the vehicle front lamp device, whether there is an open circuit in the bypass wiring; Fig. 11 is a flowchart showing a first half of a lighting control process executed by the vehicle front lighting device; Fig. 12 is a flowchart showing a second half of the lighting control process executed by the vehicle front lighting device; Fig. 13 is an example diagram of a detection time DT for detecting whether there is an interruption during the lighting control process; Fig. 14 is an example diagram showing a reason why a predetermined period for determining whether to turn off an LED is set; Fig. 15 is an example diagram illustrating a detection timing DT for detecting an interruption position in a lighting control process according to a modification; Fig. 16 is a flowchart showing a first half of the lighting control process according to the modification; Fig. 17 is a flowchart showing an intermediate portion of the lighting control process according to the modification; and Fig. 18 is a flowchart showing a second half of the lighting control process according to the modification. Description of the embodiments

[0014] A vehicle front lighting device 100 according to an embodiment of the present invention will be described with reference to the drawings. Fig. 1A shows a vehicle 1 on which a front lighting device (FL) 100 according to the present embodiment is mounted. As shown in Fig. As shown in FIG. 1A, a front lighting device 100 is mounted on each of the left and right sides of the vehicle 1, and each vehicle front lighting device 100 includes an LED array 10 in which a plurality of light-emitting diodes (hereinafter referred to as LEDs) are arranged in a row, and a control module (CM) 20 for controlling the lighting operation of the individual LEDs constituting the LED array 10. The LED arrays 10 are mounted one-by-one under headlights 2 mounted on the front left and right sides of the vehicle 1, and the control modules 20 are mounted inside the vehicle 1 within the LED arrays 10.

[0015] As it is in Fig. 1B, the control modules 20 are connected to a lamp ECU (LE) 50 mounted on the vehicle, and control the operation of lighting the individual LEDs constituting each LED array 10 according to an instruction or command from the lamp ECU 50. The lamp ECU 50 is connected to an on-vehicle LAN 30 that controls the ECUs (not shown) mounted on the vehicle 1, and determines a command content to be output to the lamp ECU 50 based on information received from other control ECUs via the on-vehicle LAN 30.

[0016] Fig. 2 shows a rough internal structure of the vehicle front lighting device 100 according to the present embodiment. As shown in Fig. As shown in FIG. 1, the vehicle front lighting device 100 according to the present embodiment includes an LED array 10 and a control module 20. The LED arrays 10 are each configured such that LEDs 1 to LEDs 12 are connected in series, and a cathode side of the LEDs 12 is grounded to GND. In the present embodiment, the LEDs 1 to LEDs 12 correspond to the "lighting devices" of the present invention, and the LED array 10 corresponds to a "lighting device array" of the present invention.

[0017] The control modules 20 each include the same number of switching elements SW1 to SW12 as the number of LEDs 1 to LED 12 in the LED arrays 10, and the switching elements SW1 to SW12 are connected in series. A bypass wiring 21a, drawn from an anode side (i.e., a side not connected to the LED 2) of the LED 1, is connected to an upstream side (i.e., a side not connected to the switching element SW2) of the switching element SW1. A bypass wiring 21b, drawn from between the LED 1 and the LED 2, is connected between the switching element SW1 and the switching element SW2. Furthermore, a bypass wiring 21c, drawn from between the LED 2 and the LED 3, is connected between the switching element SW2 and the switching element SW3.In the same way, bypass wiring 21d to 21l, which extends from between LED 3 to LED 12, is connected between switching element SW3 and switching element SW12. A bypass wiring 21m, which extends from a cathode side (i.e., a side grounded to GND) of LED 12, is connected to a downstream side (i.e., a side not connected to switching element SW11) of switching element SW12.

[0018] Therefore, when the switching element SW1 is rendered conductive, the bypass wiring 21a and the bypass wiring 21b are rendered conductive by the switching element SW1, and accordingly, a bypass circuit 21 that bypasses the LED 1 is formed. When the switching element SW2 is rendered conductive, the bypass wiring 21b and the bypass wiring 21c are rendered conductive by the switching element SW2, and accordingly, the bypass circuit 21 that bypasses the LED 2 is formed. Similarly, the switching elements SW3 to SW12 are rendered conductive to form the respective bypass circuits 21 for bypassing the LED 3 to LED 12.

[0019] A power transistor, called a switching element, is used as each of the switching elements SW1 to SW12. The power transistor has three terminals. When one of these terminals is turned high, the other two terminals are turned on. When the control terminal is turned low, the other two terminals are turned off.

[0020] In addition to the switching elements SW1 to SW12, the control module 20 also includes a lighting control unit (LC) 22, a current value detection unit 23, a voltage value control unit (VC) 24, a change amount acquisition unit (CAA) 25, and a disconnection determination unit (DD) 26.

[0021] Note that these "units" are abstract concepts according to which the interior of the control module 20 is classified for the sake of simplicity, focusing on the functions of the control module 20 of the vehicle front lighting device 100, such as illuminating LEDs 1 to LEDs 12 and detecting the presence or absence of an open circuit in the bypass wiring 21a to 21m. Therefore, it is not intended that the control module 20 of the vehicle front lighting device 100 is physically divided into these "units." These "units" may be implemented as a computer program executed by a CPU, may be implemented as an electronic circuit including an LSI and a memory, or may be implemented by combining the computer program with the electronic circuit.

[0022] The lighting control unit 22 is connected to control terminals of the switching elements SW1 to SW12, and the control terminals of the respective switching elements SW1 to SW12 can be individually brought into a high state or a low state.

[0023] The current value detection unit 23 is connected in series to the LED array 10 and can detect a value of a current flowing through the LED array 10. Since the LEDs 1 to 12 are connected in series within the LED array 10, the current value detected by the current value detection unit 23 is a value of a current flowing through each of the LEDs 1 to 12.

[0024] The voltage value control unit 24 applies a voltage to the LED array 10, receives a value of a current flowing through the LED array 10 from the current value detection unit 23, and controls a value of the voltage to be applied to the LED array so that the current value becomes equal to a predetermined target current value.

[0025] Each time a predetermined detection condition is met, the change amount acquisition unit 25 receives the number of switching elements SW1 to SW12 whose control terminals are in a low state from the lighting control unit 22 and acquires the amount of change from the last received number. Furthermore, the change amount acquisition unit 25 receives a value of the voltage applied to the LED array 10 from the voltage value control unit 24 and acquires the amount of change from the previous voltage value. The detection condition may be various, for example, every time a predetermined time has elapsed. Then, the change amount acquisition unit 25 outputs the amount of change in the number of switching elements SW1 to SW12 and the amount of change in the voltage value to the disconnection determination unit 26.

[0026] Upon receiving the magnitude of the change in the number of switching elements SW1 to SW12 and the magnitude of the change in the voltage value, the disconnection determination unit 26 determines whether both change magnitudes match. If these change magnitudes do not match, it is determined that a disconnection has occurred in at least one of the bypass wirings 21a to 21m.

[0027] Next, a method for detecting the presence or absence of a break in the bypass wirings 21a to 21m by the vehicle front lighting device 100 according to the present embodiment will be described, and preliminarily, the operation of lighting the LEDs 1 to LEDs 12 by the vehicle front lighting device 100 will be described.

[0028] The Fig. 3A and Fig. 3B show the operation of turning on or off the LED 1 to LED 12 by the vehicle front lighting device 100 according to the present embodiment. In the LED array 10, 12 LEDs, that is, the LED 1 to LED 12, are connected in series (see Fig. 2); however, in order not to complicate the illustration, LEDs 7 to LED 12 are in the Fig. 3A to 3B are omitted. Therefore, in the description of the Fig. 3A and Fig. 3B assume that the LED array 10 includes six series-connected LEDs, ie, LED 1 to LED 6, and the switching elements include the six switching elements SW1 to SW6.

[0029] When the respective control terminals of the switching elements SW1 to SW6 are in the low state, all the switching elements SW1 to SW6 are brought into an interruption state as shown in Fig. 3A. Therefore, when a voltage is applied from the voltage value control unit 24 to the LED array 10, a current flows through the LED 1 to LED 6 as indicated by the thick solid line in the drawing, and the LED 1 to LED 6 are turned on.

[0030] As it is in Fig. 3B, the control terminal of the switching element SW2 is brought into a high state (Hi). Then, the switching element SW2 is rendered conductive, and the bypass circuit 21 that bypasses the LED 2 (i.e., the bypass wiring 21b, the switching element SW2, and the bypass wiring 21c) is connected to the bypass circuit 21. Since a resistance value of the LEDs is generally larger than a resistance value of the bypass circuit 21, a current that would otherwise flow through the LED 2 flows through the switching element SW2 through the bypass circuit 21, thereby turning off the LED 2.

[0031] When the control terminals of switching element SW4 and switching element SW5 are turned high, switching element SW4 and switching element SW5 are rendered conductive. Consequently, a current that would normally flow through LED 4 and LED 5 flows through the bypass circuit 21 (i.e., bypass wiring 21d, switching element SW4, switching element SW5, and bypass wiring 21f), through switching element SW4 and switching element SW5, and LED 4 and LED 5 are turned off.

[0032] In Fig. 3B, a thick solid line represents a path through which a current flows when the control terminals of the switching element SW2, the switching element SW4, and the switching element SW5 are in the high state. In the example of Fig. 3B, light is therefore emitted by LED 1, LED 3 and LED 6.

[0033] If, as it appears from the Fig. 3A and Fig. 3B, when the lighting control unit 22 sets a control terminal of a particular switching element to the low state, the LED corresponding to the switching element SW is turned on. Conversely, when the control terminal is set to the high state, the LED corresponding to the switching element SW is turned off. Regardless of which LED is turned on, a current value of the current flowing through a respective LED is a current value detected by the current value detection unit 23.

[0034] In the example shown in Fig. 3A, a current flows through six LEDs, but in the example shown in Fig. 3B, a current flows through three LEDs and three switching elements. Since in this example the resistance value of the switching elements is sufficiently smaller than the resistance value of the LEDs, the resistance value of a path through which the current flows is changed by switching from the state of Fig. 3A in the state of Fig. 3B. If the value of the voltage applied by the voltage control unit 24 is not changed, the value of the current flowing through a respective LED is doubled. Conversely, to maintain the value of the current flowing through a respective LED at a predetermined target current value, it is necessary to halve the value of the voltage to be applied by the voltage control unit 24.

[0035] Therefore, the voltage value control unit 24 detects the current value of the LED through the current value detection unit 23 and controls the value of the voltage to be applied so that the current value reaches the target current value.

[0036] Since the current value of the LED is controlled or regulated to a constant target current value in this way, the luminance or brightness of the LED can also be changed by changing the current value. Therefore, the brightness of the LED is changed using the following method.

[0037] Fig. Figure 4 shows how the brightness of the illuminated LED is changed. As shown in the figure, the LEDs are repeatedly turned on and off in a predetermined lighting cycle. In this example, if the lighting cycle is set to a short period of time that is not noticeable to humans, by reducing the proportion of lighting time within the lighting cycle, the human may feel that the brightness of the LED is decreasing. Conversely, if the proportion of lighting time is increased, the human may feel that the brightness of the LED is increasing.

[0038] Therefore, in the vehicle front lighting device 100 according to the present embodiment, the brightness of the LED is changed by changing the timing at which the LED is turned off after the LED is periodically turned on in a predetermined lighting cycle. A state where the lighting time in the lighting cycle is "0" means off, and the lighting state is a state of maximum brightness during the lighting cycle. In the vehicle front lighting device 100 according to the present embodiment, the lighting cycle is approximately 3 ms.

[0039] As mentioned above with reference to Fig. As described in Figure 2, 12 LEDs, i.e., LED 1 to LED 12, are arranged in the LED array 10. In any one of LED 1 to LED 12, the brightness is adjusted by changing a timing at which the LEDs are periodically turned on and then off in a predetermined lighting cycle. However, the lighting cycles of LED 1 to LED 12 are set to be out of phase, which causes the timings at which LED 1 to LED 12 are turned on to be different from each other.

[0040] Fig. Figure 5 shows a state in which LEDs 1 to 12 are switched on at different times. In the example shown in Fig. As shown in Figure 5, the duty cycle for each of LEDs 1 through LED 12 is 50%. Here, the duty cycle represents a ratio or proportion of the time the LED is on to the lighting cycle.

[0041] As shown in the figure, LED 1 is turned on at time T1, LED 2 is turned on at time T2, and LED 3 is turned on at time T3. In the same way, LED 4 to LED 12 are sequentially turned on at times T4 to T12. LED 1 to LED 12, which were turned on in this order, are turned off when a predetermined time has elapsed since the lighting (in this example, half of the lighting cycle because the lighting duty cycle is set to 50%). After the lighting cycle has elapsed since LED 1 was turned on, LED 1 is turned on again, and then LED 2 to LED 12 are turned on in sequence.

[0042] In this example, when LED 1 to LED 12 are turned on at the same time, the resistance value of a path through which the voltage value control unit 24 causes a current to flow becomes a resistance value of 12 LEDs, so that the voltage value control unit 24 can apply a voltage with a large voltage value (see Fig. 3A). When LEDs 1 to LED 12 are simultaneously lit, LEDs 1 to LED 12 are simultaneously lit after a period of time corresponding to the lighting duty cycle has elapsed. Since the resistance of the path through which current flows rapidly decreases to the resistance of the 12 switching elements, it is necessary to rapidly reduce the voltage applied by the voltage control unit 24. Therefore, when LEDs 1 to LED 12 are simultaneously lit, a large voltage must be applied. As described above, when LEDs 1 to LED 12 are simultaneously lit, the voltage control unit 24 must widely vary the applied voltage.

[0043] On the other hand, as in Fig. 5, the LEDs 1 to 12 are turned on in sequence and then turned off in sequence when the phases of the lighting cycle of the LEDs 1 to 12 are shifted from each other, so that the change in the value of the voltage applied by the voltage value control unit 24 can be reduced. In particular, in the example shown in Fig. As shown in Figure 5, the lighting duty cycle of LEDs 1 to 12 is 50%, and thus the number of LEDs that light up simultaneously is six. Therefore, the voltage value control unit 24 does not need to change the voltage value.

[0044] However, the brightness at which LED 1 to LED 12 are switched on changes according to information such as the surrounding state of vehicle 1, the presence or absence of an oncoming vehicle, a pedestrian, or the like, and information such as the position at which the oncoming vehicle or pedestrian is detected. As described above with reference to Fig. 1B, when the lamp ECU 50 mounted on the vehicle 1 acquires these pieces of information via the in-vehicle LAN 30, the lamp ECU 50 determines the distribution of brightness at which the LEDs 1 to LEDs 12 are turned on (so-called light distribution pattern) and outputs the distribution to the vehicle front lighting device 100. Then, the control module 20 of the vehicle front lighting device 100 determines the timings at which the LEDs 1 to LEDs 12 are turned on and off according to the light distribution pattern.

[0045] In Fig. 6A shows the timings at which LEDs 1 to LED 12 are turned on and off according to the light distribution pattern. In the example shown in the figure, the lighting duty cycle of LEDs 1 and 2 in the light distribution pattern is 30%, the lighting duty cycle of LEDs 3 is 50%, the lighting duty cycle of LEDs 4 is 60%, the lighting duty cycle of LEDs 5 and 6 is 80%, the lighting duty cycle of LEDs 9 and 10 is 60%, and the lighting duty cycle of LEDs 11 and 12 is 50%.

[0046] As mentioned above with reference to Fig. 5, LED 1 to LED 12 are sequentially turned on at times T1 to T12. Since the lighting duty cycle of LED 1 is 30%, LED 1 is turned off at a time point at which a time corresponding to 30% of the lighting cycle has elapsed after LED 1 was turned on at time T1. Since the lighting duty cycle of LED 2 is 30%, LED 2 is turned off at a time point at which a time corresponding to 30% of the lighting cycle has elapsed after LED 2 was turned on at time T2. Since the lighting duty cycle of LED 3 is 50%, LED 3 is turned off at a time point at which a time corresponding to 50% of the lighting cycle has elapsed after LED 3 was turned on at time T3.In the same way, LEDs 4 to LED 12 are turned off at a time point when a time corresponding to each lighting duty cycle has elapsed after each LED 4 to LED 12 is turned on in sequence at the respective times T4 to T12. In this way, the timings at which LEDs 1 to LED 12 are turned on and off can be determined according to the light distribution pattern.

[0047] In this description, the timings at which LEDs 1 to LED 12 are turned on and off, which are determined according to the light distribution pattern, are referred to as a "lighting schedule." Since the timings at which LEDs 1 to LED 12 are turned on are determined in advance according to the present embodiment, only the turn-off timings are actually determined. However, the timings at which LEDs 1 to LED 12 are turned on can also be changed as needed.

[0048] After the lighting pattern of LED 1 to LED 12 has been determined as described above, LED 1 to LED 12 are turned on or off by setting the control terminals of the switching elements SW1 to SW12 to a low state or high state according to the lighting pattern.

[0049] When the lighting plan of LED 1 to LED 12 is determined, the number of LEDs to be turned on (hereinafter referred to as the number of illuminated LEDs) changes over time. Fig. Figure 6B shows a state in which the number of LEDs illuminates changes at respective moments over time.

[0050] As mentioned above with reference to the Fig. 3A and Fig. 3B, the resistance value of the path through which current flows is proportional to the number of illuminated LEDs. If the voltage value of the voltage value control unit 24 is controlled such that the current value detected by the current value detection unit 23 reaches a predetermined target current value, while the LEDs 1 to LED 12 are illuminated according to the illumination plan shown in Fig. 6A are turned on or off, the voltage value becomes a voltage value that changes proportionally to the number of LEDs illuminated.

[0051] Upon receiving the light distribution pattern from the lamp ECU 50, the vehicle front lighting device 100 according to the present embodiment sets the control terminals of the switching elements SW1 to SW12 to the low state or high state according to the lighting plan determined as described above. With the above operation, the front of the vehicle 1 can be illuminated with the light distribution pattern determined by the lamp ECU 50.

[0052] LEDs 1 to LED 12 of LED array 10 and switching elements SW1 to SW12 of control module 20 are connected to each other via bypass wiring 21a to 21m. If an open circuit occurs in any of the bypass wiring 21a to 21m, the front side cannot be illuminated with the light distribution pattern determined by lamp ECU 50, and therefore, there is a need to be able to quickly detect the open circuit when such an open circuit occurs.

[0053] On the other hand, as described above, the number of LEDs mounted in the LED array 10 tends to increase year by year, and as the number of LEDs increases, the number of bypass wiring also increases, making it more difficult to detect a disconnection year by year. Therefore, the vehicle front lighting device 100 according to the present embodiment employs the following method to be able to quickly and easily detect a disconnection in the bypass wiring even when the number of LEDs mounted in the LED array 10 is larger.

[0054] The Fig. 7A and Fig. 7B exemplifies a state in which a path through which a current flows changes due to the occurrence of a break in the bypass wiring. As described above, 12 LEDs, namely, LED 1 to LED 12, are connected in the LED array 10 of the present embodiment, but in order to avoid complicating the illustration, LED 7 to LED 12 are not shown in the Fig. 7A and Fig. 7B as in the Fig. 3A and Fig. 3B is not shown. Accordingly, in the description of the Fig. 7A and Fig. 7B assume that six LEDs, ie, LED 1 to LED 6, are connected in series in the LED array 10, and six switches, ie, switching element SW1 to switching element SW6, are present.

[0055] Fig. Figure 7A shows a situation where no interruption occurs. As shown in Fig. As shown in Figure 7A, when the control terminals of switching elements SW1, SW3, and SW6 are low and the control terminals of switching elements SW2, SW4, and SW5 are high, a current flows through a path indicated by a thick solid line in the drawing. Accordingly, LED 1, LED 3, and LED 6 are turned on, and LED 2, LED 4, and LED 5 are turned off.

[0056] In this situation, it is now assumed that an interruption occurs in the bypass wiring 21d. Since, as in Fig. As shown in Figure 7A, the bypass wiring 21d is a path that bypasses a current flow through the LED 4. If the bypass wiring 21d is interrupted, the current cannot bypass the LED 4. Accordingly, even if the control terminal of the switching element SW4 is in the high state and the switching element SW4 is in the conductive state, a current flows through the LED 4, and the LED 4 is turned on.

[0057] A thick solid line in Fig. 7B represents a path through which a current flows at this time. In addition, a mark X in the drawing indicates that an open circuit occurs in the bypass wiring 21d. Furthermore, the LED 4 surrounded by dashed lines in the drawing indicates that the LED 4 is actually turned on, although the LED 4 should be turned off in response to the switching element SW4 being conductive.

[0058] According to Fig. 7B describes a case where the broken bypass wiring 21d is part of the path for bypassing the LED 4. When the bypass wiring 21d, which is a bypass of the current through the LED 4, is broken, the current cannot bypass the LED 4 and flows through the LED 4, thereby turning on the LED 4.

[0059] The same applies if the broken bypass wiring 21d is part of the path to bypass LED 3.

[0060] Fig. 8A shows a case where the switching element SW3 on an upstream side of the broken bypass wiring 21d is in a conductive state (i.e., the control terminal is in a high state), and the switching element SW4 on a downstream side is in a broken state (i.e., the control terminal is in a low state). Since the switching element SW is in the conductive state, the current originally bypasses the LED 3, but the current cannot bypass the LED 3 because the bypass wiring 21d, which is a part of the bypass path, is broken. Accordingly, a current flows through a path indicated by a thick solid line in Fig. 8A is specified, and LED 3 is switched on. In Fig. 8A, the LED 3 surrounded by a rectangle indicates that the LED 3 is actually turned on, even if the LED 3 should be turned off in response to the switching element SW3 being made conductive.

[0061] Fig. 8B, on the other hand, shows a situation where both the switching element SW3 on the upstream side and the switching element SW4 on the downstream side of the interrupted bypass wiring 21b are rendered conductive. Since the switching element SW3 and the switching element SW4 are rendered conductive, the current bypasses the LED 3 and the LED 4. Since the bypass wiring 21d drawn from between the LED 3 and the LED 4 does not form part of a path through which the current bypasses the LED 3 and the LED 4, the LED 3 and the LED 4 remain off even if an interruption occurs in the bypass wiring 21d.

[0062] In contrast to the case described in Fig. As shown in Figure 8B, when both the upstream switching element SW3 and the downstream switching element SW4 of the interrupted bypass wiring 21d are interrupted, the current does not bypass LED 3 and LED 4 at the first location. Since the bypass wiring 21d does not form part of the current bypass path, LED 3 and LED 4 remain illuminated even if an interruption occurs in the bypass wiring 21d.

[0063] As can be seen from the above description, when an open circuit occurs in a particular bypass wiring, both LEDs will be turned on, even if one of the upstream and downstream LEDs of the bypass wiring is turned on and the other is turned off. If both LEDs are to be turned on or off, both LEDs can be turned on or off as intended.

[0064] Even if an attempt is made to turn LEDs 1 to LED 12 on and off according to a predetermined lighting plan, if there is a broken bypass wiring, the number of LEDs actually turned on (hereinafter referred to as the number of actually lit LEDs) is larger than the number of lit LEDs determined according to the lighting plan.

[0065] Fig. Figure 9A shows an example where LED 1 to LED 12 are illuminated according to the lighting plan shown in Fig. 6A, while the bypass wiring 21d, which is led out from between the LED 3 and the LED 4, is interrupted. The diagonally dashed sections in Fig. 9A indicate that the LEDs are inadvertently turned on because the bypass wiring 21d is interrupted. For example, LED 4 is turned on together with LED 3 because LED 3 turns on when LED 4 is turned on, even though the time has not yet come. Furthermore, LED 3 remains on because LED 4 continues to turn on even though the time for LED 3 to turn off has come.

[0066] As a result, the number of actual luminaires with which the LEDs are actually switched on is greater than the number of illuminated LEDs according to which the LEDs are attempted to be switched on according to the lighting plan. The shaded sections in Fig. 9B indicate the number of illuminated LEDs that increases due to an interruption.

[0067] As described above, LEDs 1 to LED 12 of LED array 10 are sequentially turned on at times T1 to T12. Therefore, it is assumed that by detecting the number of LEDs that actually light up (i.e., the number of actually lit LEDs) at a time point when a predetermined period of time has elapsed since the LEDs 1 to LED 12 were turned on, and determining whether the number of actually lit LEDs matches the number of lit LEDs corresponding to the lighting schedule, it can be determined whether an open circuit has occurred.

[0068] As mentioned above with reference to the Fig. 3A and Fig. 3B, since the voltage applied to the LED array 10 by the voltage value control unit 24 is a voltage value proportional to the number of actual light-emitting LEDs, the number of actual light-emitting LEDs can be obtained by detecting the value of the voltage applied to the LED array 10.

[0069] Fig. 10A shows Fig. 9B with an enlarged time axis. A thick solid line in the figure represents the number of LEDs lit according to the lighting plan, and the diagonally dashed sections in the figure represent sections where the number of LEDs lit is increased due to the influence of an interruption. In addition, T1 to T12 on the horizontal axis in the figure indicate the times at which LEDs 1 to LED 12 are lit.

[0070] Fig. 10B is obtained by calculating the number of LEDs lit based on the lighting plan and the number of actual LEDs lit at times DT1 to DT12 at which a predetermined time has elapsed from the respective times T1 to T12 (hereinafter referred to as detection times).

[0071] As it is in Fig. As shown in Fig. 10B, at the detection time DT3, the number of LEDs corresponding to the lighting pattern is 10, while the number of actual LEDs is 11, so the number of LEDs corresponding to the lighting pattern does not match the number of actual LEDs. Since there is no need to count the number of switching elements SW whose control terminals are in the low state at the time DT3, the number of LEDs corresponding to the lighting pattern can be obtained directly.

[0072] The number of LEDs lit can be obtained according to a value of a voltage applied to the LED array 10. In other words, assuming that a resistance value per LED is R, the number of actual LEDs lit is N, a target current value of a current flowing through the respective LEDs of the LED array 10 is I, and a value of the voltage applied to the LED array 10 by the voltage value control unit 24 is V, the following expression holds. V=I⋅(N⋅R)

[0073] In this example, (N·R) is a resistance value of the entire LED array 10 from the perspective of the voltage value control unit 24. Since V can be actually measured and I and R are given in advance, it can be assumed that the number of actual light-emitting LEDs N can be calculated.

[0074] In reality, however, there is a variation in the resistance value R of the LEDs. Therefore, when a plurality of light-emitting LEDs are LEDs with a large resistance value or LEDs with a small resistance value, a large error occurs in the resistance value of the entire LED array 10 from the perspective of the voltage value control unit 24. As the number of light-emitting LEDs increases and an error in the resistance value becomes a magnitude equivalent to the resistance value of one LED, there is a possibility that an erroneous number of actual light-emitting LEDs may be obtained by calculating the number of actual light-emitting LEDs using expression (1).

[0075] At the time DT3 in Fig. For example, in 10B, 11 LEDs are actually lit, but if the resistance values ​​of these LEDs are small, the number of actually lit LEDs is erroneously calculated as 10, and the occurrence of an open circuit cannot be detected. At times DT2 and DT4, 10 LEDs are lit, but if the resistance values ​​of these LEDs are large, the number of actually lit LEDs is erroneously calculated as 11, and the occurrence of an open circuit may be erroneously detected.

[0076] At times DT9, DT10, and DT11, the number of LEDs lit is less than at time DT3, so the possibility of erroneous detection of whether there is an open circuit is less, but when a variation in the resistance value of the LEDs becomes large, the possibility of erroneous detection still exists.

[0077] In addition, as described above, the number of LEDs constituting the LED array 10 is expected to increase, so that the number of light-emitting LEDs will also increase, which may lead to the possibility of erroneous detection of whether there is an open circuit.

[0078] Therefore, the focus is not on the number of illuminated LEDs and the number of actual illuminated LEDs at a given sampling time DT, but on the magnitude of the change in the number of illuminated LEDs and the number of actual illuminated LEDs. In other words, when the number of illuminated LEDs and the number of actual illuminated LEDs are sampled at a given sampling time DT, the number of illuminated LEDs and the number of actual illuminated LEDs are compared with the number of illuminated LEDs and the number of actual illuminated LEDs sampled at a previous sampling time DT, and the magnitude of the change in the number of illuminated LEDs and the magnitude of the change in the number of actual illuminated LEDs are calculated.

[0079] Fig. Figure 10C shows the magnitude of the change in the number of illuminated LEDs and the magnitude of the change in the number of actual illuminated LEDs obtained in this way. For example, the magnitudes of the change in the number of illuminated LEDs and the number of actual illuminated LEDs match each other with "+1" between time DT1 and time DT2, but the magnitude of the change in the number of illuminated LEDs and the magnitude of the change in the number of actual illuminated LEDs do not match each other between time DT2 and time DT3. Similarly, the magnitude of the change in the number of illuminated LEDs and the magnitude of the change in the number of actual illuminated LEDs do not match each other between time DT3 and time DT4, between time DT8 and time DT9, and between time DT11 and time DT12. The mismatch of the change magnitudes occurs because, as shown in Fig. 10B, portions where the number of light-emitting LEDs and the number of actual light-emitting LEDs differ from each other occur. Therefore, instead of detecting the number of light-emitting LEDs and the number of actual light-emitting LEDs to determine whether these numbers match, it can be determined whether the amount of change in the number of light-emitting LEDs and the amount of change in the number of actual light-emitting LEDs match or mismatch.

[0080] As can be seen from a comparison between Fig. 10B and Fig. As can be seen in Figure 10C, a variation in the resistance value of the LEDs is less likely to affect the system because the magnitude of the change in the number of actual LEDs becomes smaller than the magnitude of the change in the number of actual illuminated LEDs. For example, it is assumed that the resistance value of the LEDs varies by about ±10% with respect to the design resistance value. If at this time, 10 illuminated LEDs are used in Fig. 10B are LEDs with a large resistance value, there is a possibility that the number of actual light-emitting LEDs may be mistakenly recorded as 11. As shown in Fig. On the other hand, as shown in FIG. 10C, in the case of using the amount of change in the number of actually lit LEDs, the value "-3" is not mistakenly detected as "-2" or "-4." As described above, if attention is paid to the amount of change in the number of lit LEDs to be turned on and the amount of change in the number of actually lit LEDs, even if the number of LEDs constituting the LED array 10 increases, it can be reliably detected whether there is a disconnection.

[0081] Therefore, the vehicle front lighting device 100 according to the present embodiment detects whether there is a disconnection in the bypass wirings 21a to 21m connecting the LED array 10 and the control module 20 based on the above principle.

[0082] The Fig. 11 and Fig. 12 show flowcharts of a lighting control process executed by the vehicle front lighting device 100 according to the present embodiment to illuminate the area in front of the vehicle 1 using the LED array 10.

[0083] As shown in the figure, when the lighting control process is started, it is first determined whether lighting is to be started using the LED array 10 (S100). In the present embodiment, the lamp ECU 50 determines whether lighting is required based on the information acquired from the on-vehicle LAN 30 and outputs the result to the vehicle front lighting device 100. Therefore, if an instruction to start lighting is not received from the lamp ECU 50, it is determined that lighting is not to be started (No in S100), and the lighting control process is in a wait state while repeating the same determination until the command to start lighting is received.

[0084] When a lighting start command is received, the lighting start is determined (Yes in S100), and the light distribution pattern is acquired from the lighting ECU 50 (S101). As described above, the light distribution pattern is information indicating the brightness at which the LEDs of the LED array 10 are turned on.

[0085] Subsequently, a lighting plan is generated according to the light distribution pattern (S102). As described above, the lighting plan consists of data indicating a schedule of times at which the LEDs forming the LED array 10 are turned on and off. As exemplified in Fig. 6A, the Fig. 6A is generated when the light distribution pattern is a pattern according to which a lighting duty ratio of the LED 1 and the LED 2 is 30%, the lighting duty ratio of the LED 3 is 50%, the lighting duty ratio of the LED 4 is 60%, the lighting duty ratio of the LED 5 to LED 8 is 80%, the lighting duty ratio of the LED 9 and the LED 10 is 60%, and the lighting duty ratio of the LED 11 and the LED 12 is 50%.

[0086] Then, according to the generated lighting plan, control of the switching elements SWs corresponding to the respective LEDs is started (S103). In other words, according to the lighting plan, the operation of setting the control terminal of the switching element SW of the LED to be turned on to the low state and setting the control terminal of the switching element SW of the LED to be turned off to the high state is repeated in the lighting cycle of the LED.

[0087] Subsequently, it is determined whether a command is issued from the lamp ECU 50 (S104), and when no command to stop lighting is issued from the lamp ECU 50, it is determined that lighting is not stopped (No in S104), and then it is determined whether the lighting cycle has elapsed (S105).

[0088] If the lighting cycle has not yet elapsed since the control of the switching elements SW was started, the result of the determination in S105 is “No”, and it is determined whether the current time is the interruption detection time DT (S110 in Fig. 12). As stated above with reference to the Fig. 10A to 10C, the detection timing DT is set to a time at which a predetermined interval period IT has elapsed since a respective LED of the LED array 10 was turned on. The reason why the interruption detection timing DT is set to such a time is that the voltage value control unit 24 requires a certain period of time to change the voltage value.

[0089] Fig. 13 illustrates a time change in the value of the voltage applied by the voltage value control unit 24 to the LED array 10 when the LED 1 is turned on at time T1. As shown in the figure, even if the number of light-emitting LEDs is changed to another, a time delay occurs in the change in the value of the voltage. This is because the voltage value control unit 24 controls the value of the voltage so that the current value detected by the current value detection unit 23 reaches the target current value. Therefore, a time required for stabilizing the voltage value with a margin (i.e., an interval period IT) is determined in advance, and a time at which the interval period IT has elapsed since the times T1 to T12 at which the LED 1 to LED 12 were turned on, respectively, is set as an open-circuit detection time DT.The above setting can prevent erroneous determination of an open circuit due to detection of a voltage value before stabilization.

[0090] If the interval period IT has not elapsed since the respective times T1 to T12 at which the respective LED 1 to LED 12 were turned on, it is determined that the time is not an interruption detection time (No in S110 of the Fig. 12), and then the river returns to S104 in Fig. 11, at which it is determined whether the lighting should be stopped. If the lighting should not be stopped (No in S104), it is determined whether the lighting cycle has elapsed (S105), and if the lighting cycle has not elapsed (No in S105), it is determined again whether the time is an interruption detection time (S110 in Fig. 12).

[0091] Even while the above operation is repeated, the control of the switching elements SWs set in S103 in Fig. 11 is started, continues according to the lighting plan.

[0092] If the current time is an interruption detection time DT (Yes in S110 in Fig. 12), it is then determined whether there are any LEDs to be turned off within a predetermined period (S111). In this example, the predetermined period is set to a time obtained by adding a predetermined margin time dT (a time shorter than the interval period IT) to the interval period IT.

[0093] If there is no LED to be turned off within the predetermined period (No in S111), the following operation is started to detect whether there is an interruption, but if there is an LED to be turned off within the predetermined period (Yes in S111), it is determined whether to stop lighting without detecting an interruption (S104 in Fig. 10). The reason why the operation is different depending on whether there is an LED to be turned off during the predetermined period is as follows.

[0094] Fig. Fig. 14 shows an enlarged view of a change in the number of lights and a change in the value of the applied voltage before and after the time T11. As described above with reference to the Fig. 6A and Fig. 6B, the number of LEDs is increased by one, thereby increasing a value of the applied voltage, as shown by the dashed line in Fig. 14, since time T11 is the time at which LED 11 is turned on. However, before the voltage value stabilizes (i.e., before the detection time DT arrives), the other LEDs are turned off, and the number of illuminated LEDs is decremented by one. As a result, the increased voltage value decreases.

[0095] Therefore, if there is an LED to be turned off during the period from the lighting time point (T11 in this example) to the elapse of the interval period IT, the voltage value during the decrease is detected when the voltage value is detected at the break detection time point DT, so that a correct voltage value cannot be detected.

[0096] It is also assumed that there is an LED that is being turned off at the detection time DT. Considering that it takes some time to detect the voltage value, in this case, the voltage value starts decreasing while the voltage value is being detected, and the correct voltage value cannot be detected. If there is an LED that is to be turned off during a period from the detection time DT until the elapse of a margin time dT, where the time required to detect the voltage value is the margin time dT, there is a possibility that the correct voltage value cannot be detected.

[0097] Therefore, in S111 the Fig. 12 determines whether there is an LED that will be turned off within a predetermined period from any of the lighting times T1 to T12 until the interval period IT and a margin time dT have elapsed. If there is an LED to be turned off (Yes in S111), it is determined that there is a possibility that correct voltage values ​​cannot be detected, and then the flow returns to S104 in Fig. 11 without detecting whether there is an interruption, and it is determined whether to stop the lighting.

[0098] Since LEDs 1 to 12 are switched on and off according to a lighting plan that is determined according to the light distribution pattern (see Fig. 6A and Fig. 6B), it can also be easily determined with reference to the lighting plan whether there is an LED that is to be turned off within a predetermined period.

[0099] Since the above-described margin time dT is indeed sufficiently shorter than the interval period IT, the margin time dT can simply be ignored. In this example, in S111, the Fig. 12 determines whether there is an LED to be turned off during a period from any lighting time T1 to T12 until the interval period IT elapses (ie until the interruption detection time DT has arrived).

[0100] If there is no LED to be turned off within the predetermined period (No in S111), the number of LEDs to be turned on (ie, the number of LEDs to be turned on) is obtained (S112). The number of LEDs lit can be obtained based on the lighting schedule.

[0101] Subsequently, the amount of change relative to the number of illuminations acquired at the previous time is acquired (S113). As described above, if there is an LED to be turned off within the predetermined period (Yes in S111), the number of illumination LEDs is not acquired, and therefore, the number of illumination LEDs acquired before the predetermined period becomes the number of illumination LEDs acquired at the previous time, and the amount of change relative to the number of illumination LEDs is acquired.

[0102] When the amount of change in the number of light-emitting LEDs has been obtained in this way, the value of the voltage applied to the LED array 10 is obtained (S114).

[0103] Subsequently, the magnitude of the change relative to the voltage value acquired at the previous time is acquired (S115). As described above, if there is an LED to be turned off within the predetermined period (Yes in S111), the voltage value is not acquired in the same way as the number of LEDs to be turned on, and therefore the magnitude of the change relative to the previously acquired voltage value is also acquired.

[0104] Then, it is determined whether the magnitude of the change in the number of LEDs obtained in S113 matches the magnitude of the change in the voltage value obtained in S115 (S116). In other words, if the magnitude of the change in the number of LEDs obtained in S113 is dN, the average resistance of the LEDs is R, a variation in the resistance value is dR, and a target current value of the current flowing through the LEDs is I, the magnitude of the change dV in the voltage value applied to the LED arrays 10 should be within the following range. dN⋅(R−dR)⋅I <dV<dN⋅(R+dR)⋅I

[0105] Therefore, if the magnitude of the change in the value of the voltage obtained in S115 is within a range that satisfies the expression (2), it is determined that the magnitude of the change in the number of light-emitting LEDs matches the magnitude of the change in the value of the voltage (Yes in S116), and if the magnitude of the change in the number of light-emitting LEDs is not within the range that satisfies the expression (2), it is determined that the magnitude of the change in the number of light-emitting LEDs does not match the magnitude of the change in the value of the voltage (No in S116).

[0106] If it is determined that the amount of change in the number of LEDs and the amount of change in the voltage value do not match each other (No in S116), the detection result “Open circuit” is accordingly output to the outside (for example, the lamp ECU 50 in Fig. 1B) is output (S117), the flow returns to S104 in Fig. 11 and determine whether to stop the lighting.

[0107] On the other hand, if it is determined that the amount of change in the number of LEDs lit and the amount of change in the voltage value match each other (Yes in S116), the flow returns to S104 in Fig. 11 without outputting the detection result, and it is determined whether to stop lighting.

[0108] As described above, in the lighting control process according to the present embodiment, when the driving of the switching elements SWs is started according to the lighting plan corresponding to the light distribution pattern (S103), by repeating the above-described operation (S116 and S117 in Fig. 12) detects whether there is an interruption.

[0109] If the lighting cycle elapses during the repetition of the above operation (Yes in S105 of the Fig. 11), the light distribution pattern is obtained from the lamp ECU 50 (S106).

[0110] Then, it is determined whether the newly acquired light distribution pattern has changed from the previously acquired light distribution pattern (S107). If there is no change in the light distribution pattern (No in S107), the above-described sequence of processes (S110 to S117 in Fig. 12) is repeated until the lighting cycle has elapsed and the result of the determination in S105 is “Yes”.

[0111] On the other hand, if the newly acquired light distribution pattern has changed from the previously acquired light distribution pattern (Yes in S107), a new lighting plan is generated according to the new light distribution pattern (S108). After starting the control of the switching elements SWs according to the new lighting plan (S109), it is determined whether the current time is the interruption detection time DT (S110 in Fig. 12), and then the above-described sequence of operations (S111 to S117) is repeated. These operations are repeated until the lighting is stopped (Yes in S104) or until the lighting cycle has elapsed (Yes in S105).

[0112] If it is finally determined that the lighting is to be stopped (Yes in S104 of the Fig. 11), the lighting control process of the Fig. 11 and Fig. 12 finished.

[0113] As described above, the vehicle front lighting device 100 according to the present embodiment can quickly detect the occurrence of an open circuit by performing the above-described lighting control process when an open circuit occurs in the bypass wirings 21a to 21m for controlling the lighting operation of the respective LEDs of the LED array 10.

[0114] In addition, when detecting the open circuit, it is only necessary to determine whether the magnitude of the change in the number of light-emitting LEDs to be turned on in the LED array 10 matches the magnitude of the change in the value of the voltage to be applied to the LED array 10, so that it is possible to easily and quickly detect whether there is an open circuit. Modifications

[0115] The following modifications are made to the above embodiment. The modifications will be briefly described below, mainly with regard to differences from the present embodiment.

[0116] In the embodiment described above, the number of light-emitting LEDs to be turned on and the value of the voltage to be applied to the LED array 10 are detected at predetermined detection times DT after the LEDs 1 to 12 are turned on, and the amount of change in the number of light-emitting LEDs and the amount of change in the voltage value are obtained.

[0117] Alternatively, the number of LEDs lit and the voltage value are detected at a predetermined detection time which is set as a reference before and after a time at which LEDs 1 to LED 12 are turned on, so that the amount of change in the number of LEDs lit and the amount of change in the voltage value can be obtained.

[0118] As is the case, for example, in Fig. 15, a detection time point DT1f set to before lighting and a detection time point DT1r set to after lighting are set for the time point T1 at which the LED 1 is turned on. A detection time point DT2f before lighting and a detection time point DT2r after lighting are also set for the time point T2 of the lighting of the LED 2. Hereinafter, in a similar manner, detection times DT3f to DT12f before lighting and detection times DT3r to DT12r after lighting are set for the respective times T3 to T12 at which the respective LEDs 3 to LED 12 are turned on. The number of lighting LEDs and the value of the voltage can be detected before and after the LED is turned on, and the amount of change in the number of lighting LEDs and the amount of change in the value of the voltage can be obtained to determine whether there is an open circuit.

[0119] The Fig. 16 to 18 show flowcharts of a lighting control process according to a modification for detecting whether there is an interruption by the method described above.

[0120] As shown in the figure, in the lighting control process according to the modification, as in the lighting control process according to the present embodiment described above, it is first determined whether lighting is to be started using the LED array 10 (S200). If it is determined that lighting is not to be started (No in S200), a wait state is set while repeating the same determination, but if it is determined that lighting is to be started (Yes in S200), the light distribution pattern is acquired from the lamp ECU 50 (S201).

[0121] After the lighting plan has been generated according to the light distribution pattern (S202), the control of the switching elements SWs corresponding to the respective LEDs is started according to the lighting plan (S203).

[0122] Next, it is determined whether the lighting should be stopped (S204), and if the lighting should not be stopped (No in S204), it is determined whether the lighting cycle has elapsed (S205). If the lighting cycle has not elapsed (No in S205), it is determined whether the current time is the detection time DTf before a lighting (S210 in Fig. 17). As stated above with reference to Fig. As described in Figure 15, in the lighting control process according to the modification, the detection timing DTf before lighting and the detection timing DTr after lighting are set to before and after the timing at which the respective LEDs 1 to LED 12 are turned on. Therefore, it is determined in S210 whether any detection timing DTf has come.

[0123] If it is determined that the detection time DTf is not detected (No in S210), the flow returns to S204 in Fig. 16, and it is determined whether the lighting is to be stopped. If the lighting is not to be stopped (No in S204), it is determined whether the lighting cycle has elapsed (S205), and if the lighting cycle has not elapsed (No in S205), it is determined whether the detection time DTf has come before a lighting (S210 in Fig. 17).

[0124] If it is determined during the repetition of the above operation that the detection timing DTf has come before lighting, (Yes in S210 of the Fig. 17), it is determined whether there is an LED to be turned off within a predetermined period (S211). In the case of the modification, similar to the above-described embodiment, the predetermined period is set to a time obtained by adding a predetermined margin time dT (a time shorter than the interval period IT) to the interval period IT. Furthermore, similar to the above-described embodiment, the margin time dT may simply be ignored.

[0125] If there is an LED to be turned off within the predetermined period (Yes in S211), it is determined whether the lighting is to be stopped (S204 in Fig. 16). On the other hand, if there is no LED to be turned off within the predetermined period (No in S211 of the Fig. 17), the number of light-emitting LEDs (i.e., the number of LEDs to be turned on) is obtained (S212), and then the value of the voltage applied to the LED array 10 is obtained (S213).

[0126] Next, in the lighting control process according to the modification, it is determined whether the current time is the detection time DTr after lighting (S214). In other words, in the lighting control process according to the modification, the detection time DTf before lighting and the detection time DTr after lighting are set to before and after the time at which the respective LEDs 1 to LED 12 are turned on. Since the detection time DTf before lighting has already been determined in S210, it is now determined whether the detection time DTr after lighting has arrived.

[0127] If it is determined that the detection timing DTr has not yet arrived (No in S214), the same determination is repeated until the detection timing DTr has arrived, thereby entering a waiting state.

[0128] A time from the time the LED is turned on to the detection time DTr after the LED is turned on is set to a time obtained by adding a predetermined margin time dT to the interval period IT similarly to the detection time DT of the present embodiment described above.

[0129] If it is determined that the detection time DTr has come after lighting (Yes in S214 of the Fig. 17), it is determined whether the number of LEDs illuminated and the voltage value at the detection time DTf before lighting were detected (S215). If the number of LEDs illuminated and the voltage value were not detected at the detection time DTf before lighting (No in S215), because the magnitude of the change before and after lighting cannot be obtained, it is determined whether lighting should be stopped (S204 in Fig. 16).

[0130] On the other hand, when the lighting number and the voltage value at the detection time DTf before lighting are detected (Yes in S215), it is determined whether there is an LED to be turned off within a predetermined period (S216).

[0131] If there is an LED to be turned off within the predetermined period (Yes in S216), it is determined whether the lighting is to be stopped (S204 in Fig. 16), but if there is no LED to be turned off within the predetermined period (No in S216 of the Fig. 17), the number of LEDs lit at the detection time DTr after one lighting is obtained (S217), and then the value of the voltage applied to the LED array 10 is obtained (S218).

[0132] As described above, the time from the time the LED is turned on to the detection time DTr after lighting is set to the time obtained by adding the predetermined margin time dT to the interval period IT. On the other hand, the time from the detection time DTf before lighting to the time the LED is turned on may be set to a time shorter than the interval period IT. The reason for this is that in S216, before the detection time DTf, it is determined whether there is an LED to be turned off within a predetermined period, and if there is no LED to be turned off (No in S216), there is no risk of detecting the voltage value at a time during a change in the voltage value.

[0133] Then, the amount of change in the number of light-emitting LEDs before and after lighting is obtained based on the number of light-emitting LEDs at the detection time DTf before lighting obtained in S212 and the number of light-emitting LEDs at the detection time DTr after lighting obtained in S217 (S219 in Fig. 18).

[0134] In addition, the amount of change in the value of the voltage before and after lighting is acquired based on the value of the voltage at the detection time DTf before lighting acquired in S213 and the value of the voltage at the detection time DTr after lighting acquired in S218 (S220).

[0135] Then, in the same manner as in S115 of the lighting control process according to the present embodiment described above, it is determined whether the magnitude of the change in the number of LEDs illuminated matches the magnitude of the change in the voltage value (S121). If it is determined that the magnitude of the change in the number of LEDs illuminated and the magnitude of the change in the voltage value do not match (No in S121), the detection result "disconnection" is transmitted to the outside (for example, the lighting ECU 50 in Fig. 1B) is output (S222), the flow returns to S204 in Fig. 16 and it is determined whether the lighting should be stopped.

[0136] On the other hand, if it is determined that the amount of change in the number of LEDs lit and the amount of change in the voltage value match each other (Yes in S221), the flow returns to S204 in Fig. 16 without outputting the detection result, and then it is determined whether to stop lighting.

[0137] The following operation in the lighting control process of the modification is the same as in the lighting control process of the above embodiment. As briefly described below, when the lighting cycle has elapsed after repeating the above-described operation (Yes in S205 of the Fig. 16), the light distribution pattern is acquired from the lamp ECU 50 (S206). Then, it is determined whether the newly acquired light distribution pattern has changed from the previously acquired light distribution pattern (S207). If there is no change in the light distribution pattern (No in S207), the above-described sequence of processes is repeated until the lighting cycle has elapsed and the result of the determination in S205 is "Yes."

[0138] On the other hand, if the newly acquired light distribution pattern has changed from the previously acquired light distribution pattern (Yes in S207), a new lighting plan is generated according to the new light distribution pattern (S208), and the control of the switching elements SWs is started according to the lighting plan (S209). After determining whether the current time is the detection time DTf before lighting (S210 in Fig. 17), the sequence of operations described above is repeated.

[0139] If it is finally determined that the lighting is to be stopped (Yes in S204 of the Fig. 16), the lighting control process is carried out according to the modification described in the Fig. 16 to 18 is finished.

[0140] In the lighting control process according to the modification described above, it can be determined whether the magnitude of the change in the number of LEDs lit matches the magnitude of the change in the voltage value before and after the respective LEDs 1 to 12 are turned on. Therefore, if a mismatch occurs, it can be determined that the bypass wiring drawn from the downstream side of the LED to be turned on is broken when the mismatch occurs.

[0141] While the present invention has been described with reference to its embodiments, it should be understood that the invention is not limited to the embodiments and constructions. The present invention covers various modifications and equivalent arrangements. In addition to the various combinations and configurations, other combinations and configurations including more, fewer, or only a single element are possible within the scope of the present invention.

Claims

[1] Vehicle front lighting device (100) for illuminating an area in front of a vehicle (1) using a plurality of lighting devices (LED 1 to LED 12) in a divided manner, the vehicle front lighting device comprising: a lighting device array (10) in which the lighting devices are connected in series; a plurality of bypass circuits (21) arranged for the respective lighting devices and allowing a current flowing through the lighting devices to bypass the lighting devices; a plurality of switching elements (SW1 to SW12) arranged for the respective bypass circuits for opening and closing the bypass circuits; a lighting control unit (22) that controls a lighting mode of the lighting device array by bringing the switching elements corresponding to the lighting devices to be turned on into an open state and bringing the switching elements corresponding to the lighting devices to be turned off into a closed state; a current value detecting unit (23) that detects a value of a current flowing through the lighting device array; a voltage value control unit (24) that applies a voltage to the lighting device array and controls a value of the voltage to be applied to cause the value of the current flowing through the lighting device array to reach a predetermined target current value; a change amount acquisition unit (25) that detects the number of switching elements brought into the open state and the value of the controlled voltage each time a predetermined detection condition is met, and acquires a change amount from the number of switching elements detected last time and a change amount from a value of the voltage detected last time; and a disconnection determining unit (26) that determines whether the amount of change in the number of switching elements matches the amount of change in the value of the voltage, and determines that a disconnection has occurred in any of the bypass circuits if it does not match. [2] Vehicle front lighting device according to claim 1, wherein the lighting control unit controls a brightness of the lighting devices by opening and closing the switching elements in a predetermined cycle and changing a time proportion of the open state in the predetermined cycle, and Phases of the predetermined cycle for opening and closing the switching elements can be set offset from one another among the switching elements. [3] Vehicle front lighting device according to claim 2, wherein the lighting control unit sets each of the switching elements to the open state at a predetermined lighting time set on the basis of the predetermined cycle of the respective switching elements, and then sets the respective switching elements to the closed state at an off time corresponding to the time portion set for the respective switching elements, and the change amount acquiring unit detects the number of switching elements and the value of the voltage at a predetermined detection time point set based on a time point at which any one of the switching elements reaches the lighting time point, to acquire the amounts of change in the number of switching elements and the value of the voltage. [4] The vehicle front light device according to claim 2, wherein the change amount acquiring unit acquires the amounts of change in the number of the switching elements and the value of the voltage by detecting the number of the switching elements and the value of the voltage at predetermined detection times set to before and after a time as a reference at which any one of the switching elements is turned on. [5] The vehicle front light device according to claim 3 or 4, wherein the change amount acquiring unit stops acquiring the amounts of change in the number of switching elements and the value of the voltage when there is a switching element among the switching elements that is changed to the closed state within a predetermined period based on the detection time point. [6] A break detection method used in a vehicle front lighting device (100) for illuminating an area in front of a vehicle (1) using a lighting device array (10) in which a plurality of lighting devices (LED 1 to LED 12) are connected in series, for detecting whether a break has occurred in a wiring for driving the lighting devices, the vehicle front lighting device comprising: a plurality of bypass circuits (21) arranged for the respective lighting devices and allowing a current flowing through the lighting devices to bypass the lighting devices; a plurality of switching elements (SW1 to SW12) arranged for the respective bypass circuits for opening and closing the bypass circuits; and a lighting control unit (22) that controls a lighting mode of the lighting device array by bringing the switching elements corresponding to the lighting devices to be turned on into an open state and bringing the switching elements corresponding to the lighting devices to be turned off into a closed state, and wherein the interruption detection method comprises: Applying a voltage to the lighting device array, detecting a value of a current flowing through the lighting device array, and controlling a value of the voltage applied to the lighting device array to cause the value of the current flowing through the lighting device array to reach a predetermined target current value (S103, S109, S203, S209); detecting the number of switching elements brought into the open state each time a predetermined detection condition is satisfied, and obtaining a magnitude of change from the number of switching elements detected last time (S112, S113, S212, S217, S219); detecting a value of the voltage applied to the light-emitting device array each time the detection condition is met and obtaining the magnitude of the change from the value of the voltage detected the last time (S114, S115, S213, S218, S220); and Determine whether the magnitude of the change in the number of switching elements matches the magnitude of the change in the value of the voltage, and determine that the interruption has occurred in any of the bypass circuits if it does not match (S116, S117, S221, S222).

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