Vehicle lighting control device

Abstract

An on-vehicle lamp control device according to the present invention comprises a motor control unit and a semiconductor light source control unit. The semiconductor light source control unit includes: a DC-DC boost converter unit that boosts a battery voltage to a predetermined voltage which is lower than the total value of the forward step-down voltages of a plurality of LEDs; a DC-DC step-down converter unit that steps down an output voltage from the DC-DC boost converter unit; a plurality of FETs that divide a plurality of LEDs into a plurality of LED groups and cause an electric current supplied from the DC-DC step-down converter unit to flow to each LED group; and a signal processing unit that controls the DC-DC boost converter unit, the DC-DC step-down converter unit, and the plurality of FETs so as to control the lighting of a plurality of semiconductor light sources. The signal processing unit performs control so as to turn on the LEDs at different times according to the respective LED groups. The motor control unit receives the output voltage from the DC-DC boost converter unit and controls a driving signal which drives a motor.

Description

[Technical Field]

[0001] The present disclosure relates to a control device for an in-vehicle lamp. [Background technology]

[0002] A semiconductor light source control device (Lighting Control Module: LCM) that supplies power to semiconductor light sources such as LEDs and controls the lighting of the semiconductor light sources, which are used as headlights and decorative elements for vehicles such as automobiles and motorcycles, and a motor control device (Auto Levelizer: ALV) that controls a motor for adjusting the optical axis of the headlight, are known to be configured in separate, independent housings (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-62686 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-78810 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been an increasing demand for multifunctionality and integration of automotive lighting control devices, and semiconductor light source control devices and motor control devices are no exception. Although integration of these devices has been considered, the semiconductor light source control device, which is driven by several tens of volts, and the motor control device, which is driven by battery voltage (approximately 12 volts), have different power supplies, making them difficult to simply integrate.

[0005] For example, a semiconductor light source control device requires a voltage of several tens of volts when supplying power to several tens of LEDs connected in series. For this reason, the semiconductor light source control device is equipped with a boost DC-DC converter that boosts the battery voltage (approximately 12 V) to several tens of volts.

[0006] On the other hand, motor control devices drive motors such as stepping motors by receiving a battery voltage of approximately 12 V. Therefore, it was not possible to directly supply the voltage of several tens of volts supplied to semiconductor light source control devices to the motor control devices.

[0007] Therefore, an object of the present disclosure is to provide a multifunctional and simple vehicle lighting control device that enables integration of a semiconductor light source control device and a motor control device that have different supply voltages. [Means for solving the problem]

[0008] The automotive lighting control device according to the present disclosure includes a motor control unit that controls a drive signal that drives a motor used in an automotive lighting device having a plurality of semiconductor light sources connected in series, and a semiconductor light source control unit that controls the lighting of the plurality of semiconductor light sources. The semiconductor light source control unit includes a boost unit that boosts the battery voltage to a predetermined voltage that is lower than the total value of the forward drop voltages of the plurality of semiconductor light sources, a step-down unit that steps down the output voltage of the boost unit, a plurality of switching units that divide the plurality of semiconductor light sources into a plurality of groups and pass current supplied from the step-down unit to each group, and a signal processing unit that controls the lighting of the plurality of semiconductor light sources by controlling the boost unit, the step-down unit, and the plurality of switching units. The signal processing unit controls the lighting of each semiconductor light source in each group at a different time, and the motor control unit receives the output voltage of the boost unit and controls the drive signal that drives the motor. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to integrate a semiconductor light source control device and a motor control device that have different supply voltages, and to realize a multifunctional and simple control device for an in-vehicle lamp.

[0010] The objects, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a configuration diagram of an in-vehicle lamp control device according to a first embodiment. [Figure 2] 4 is a timing chart showing the output voltage of the step-down DC-DC converter unit and the voltage and current of each LED group in the first embodiment. FIG. [Figure 3] FIG. 10 is a configuration diagram of an in-vehicle lamp control device according to a second embodiment. [Figure 4] 10 is a diagram showing a timing chart of the output voltage of the step-down DC-DC converter unit and the voltage and current of each LED group in embodiment 2. FIG. [Figure 5] FIG. 10 is a configuration diagram of an in-vehicle lamp control device according to a third embodiment. [Figure 6] FIG. 11 is a timing chart showing the voltage of each LED group, the maximum value of the output voltage of the step-up DC-DC converter, and the input voltage of the motor current supply unit in the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] <First Embodiment> <Configuration of an in-vehicle lighting control device> The first embodiment will be described below with reference to the drawings. Fig. 1 is a configuration diagram of an in-vehicle lamp control device 100 according to the first embodiment.

[0013] 1, the vehicle lighting control device 100 includes a semiconductor light source control unit (LCM) 20 as a semiconductor light source control device, and a motor control unit (ALV) 40 as a motor control device. The semiconductor light source control unit 20 is connected to a battery 10, a host unit (not shown), and LED groups G1 and G2. The motor control unit 40 is connected to a host unit (not shown) and a motor 50.

[0014] The semiconductor light source control unit 20 includes a signal processing unit 21, a step-up DC-DC converter unit 22, a step-down DC-DC converter unit 23, and FETs (Field Effect Transistors) 24a and 24b. Here, the step-up DC-DC converter unit 22 corresponds to a step-up unit, the step-down DC-DC converter unit 23 corresponds to a step-down unit, and the FETs 24a and 24b correspond to a switching unit.

[0015] The signal processing unit 21 receives an instruction from a higher-level unit (not shown) or an instruction from the driver to turn on the lights, and transmits control signals to each unit of the semiconductor light source control unit 20. That is, the signal processing unit 21 controls the step-up DC-DC converter unit 22, the step-down DC-DC converter unit 23, and the FETs 24a and 24b.

[0016] The step-up DC-DC converter unit 22 steps up the voltage of the battery 10 (hereinafter also referred to as "battery voltage") to a predetermined voltage.

[0017] The step-down DC-DC converter unit 23 steps down the output voltage of the step-up DC-DC converter unit 22, and outputs a current having a current value calculated by the signal processing unit 21.

[0018] The FETs 24a and 24b are connected in parallel with a plurality (several to about ten) of series-connected LEDs 31 (corresponding to semiconductor light sources), and divide the LED group into a plurality (for example, two) of LED groups G1 and G2. In addition, upon receiving an instruction from the signal processing unit 21, the FETs 24a and 24b cause the current supplied from the step-down DC-DC converter unit 23 to flow to each of the LED groups G1 and G2 for a predetermined time.

[0019] The LED groups G1 and G2 are LED groups that are built into the vehicle lamp and light up when power is supplied from the step-down DC-DC converter unit 23. In each of the LED groups G1 and G2, a plurality of LEDs 31 are connected in series.

[0020] The motor control unit 40 includes a light axis control unit 41 and a motor current supply unit 42. The light axis control unit 41 controls the light axis of the vehicle lamp in response to instructions from a higher-level unit (not shown) or signals from a detector (not shown). For example, the light axis control unit 41 adjusts the light axis of the headlight depending on the situation.

[0021] The motor current supply unit 42 receives the output voltage from the step-up DC-DC converter unit 22 and supplies it to the motor 50. The motor 50 is used in an in-vehicle lamp. Specifically, the motor 50 is used to adjust the optical axis of the in-vehicle lamp, and is configured by, for example, a stepping motor.

[0022] <Operation of the vehicle lighting control device> Next, we will explain the operation of the automotive lighting control device 100. As shown in Fig. 1, the battery voltage supplied from the battery 10 is boosted from approximately 12V to several tens of volts and output from the boost DCDC converter unit 22. The boost DCDC converter unit 22 receives the battery voltage and boosts it to a predetermined voltage that is higher than the battery voltage and lower than the total value (ΣVf) of the forward drop voltages of the LED groups G1 and G2 connected in series.

[0023] More specifically, the output voltage of the step-up DCDC converter unit 22 is set so that the following relationship holds: battery voltage < maximum instantaneous output voltage of the step-down DCDC converter unit 23 < output voltage of the step-up DCDC converter unit 22 < withstand voltage of the motor current supply unit 42. This makes it possible to integrate the semiconductor light source control unit 20, which is a semiconductor light source control device, and the motor control unit 40, which is a motor control device. The output voltage of the step-up DCDC converter unit 22 is supplied to both the step-down DCDC converter unit 23 in the semiconductor light source control unit 20 and the motor current supply unit 42 in the motor control unit 40.

[0024] Furthermore, the signal processing unit 21 receives an instruction from a higher-level unit (not shown) or an instruction from the driver to turn on the LEDs, and adjusts the current supplied to the LED groups G1 and G2 by controlling the output voltage of the step-up DC-DC converter unit 22, the output current of the step-down DC-DC converter unit 23, and the on / off of the FETs 24a and 24b. In particular, the signal processing unit 21 adjusts the current so that a visually smoothed average brightness can be obtained by blinking the LED groups G1 and G2 at a cycle that is difficult to see.

[0025] That is, the semiconductor light source control unit 20 incorporates a signal processing unit 21, a step-up DCDC converter unit 22, a step-down DCDC converter unit 23, and FETs 24a and 24b, and upon receiving a so-called lighting mode instruction from a higher-level unit (not shown) or a lighting instruction from the driver, lights up the LED groups G1 and G2 and controls the output voltage of the step-down DCDC converter unit 23 to be equal to or lower than a predetermined constant value (a value set by the signal processing unit 21, specifically equivalent to the withstand voltage of the motor current supply unit 42), thereby controlling the current value flowing through the LED groups G1 and G2. The current value of the current flowing through the LED groups G1 and G2 is detected by the step-down DCDC converter unit 23. The signal processing unit 21 and the step-down DCDC converter unit 23 control the current value flowing through the LED groups G1 and G2 so that it becomes a target current value.

[0026] Here, the relationship between the output voltage of the step-down DCDC converter unit 23 and the voltage and current of each LED group G1, G2 will be described using Fig. 2. Fig. 2 is a diagram showing a timing chart of the output voltage of the step-down DCDC converter unit 23 and the voltage and current of each LED group G1, G2 in embodiment 1. Note that LED_G1 in Fig. 2 indicates the LED 31 belonging to the LED group G1, and LED_G2 indicates the LED 31 belonging to the LED group G2.

[0027] Assuming that the number of LEDs 31 connected to the FETs 24a and 24b is 16, each of the LED groups G1 and G2 includes 8 LEDs 31. To drive all 16 LEDs 31 that belong to the series-connected LED groups G1 and G2, approximately ΣVf=3V×16=48V is required.

[0028] In contrast, when the FETs 24a and 24b are used to duty control each of the LED groups G1 and G2 and the 16 LEDs 31 belonging to the LED groups G1 and G2 are turned on at different times for each LED group G1 and G2, the required voltage is approximately ΣVf=3V×8=24V, and the required voltage can be suppressed. In other words, by making the voltage required to turn on the 16 LEDs 31 belonging to the LED groups G1 and G2 and the output voltage of the step-up DC-DC converter unit 22 output to the motor control unit 40 close to each other, it becomes possible to integrate the semiconductor light source control unit 20 as a semiconductor light source control device and the motor control unit 40 as a motor control device.

[0029] However, if left as is, the LED 31 will become dim, so as shown in Figure 2, if the duty ratio is 50% and the current originally flowing through the LED 31 is 1 A, the current output from the step-down DCDC converter 23 is set to 2 A instead of suppressing the output voltage of the step-up DCDC converter 22, so that an average current of 1 A flows. Also, by setting the frequency during duty control to 60 Hz or higher, it is possible to address the practical problem of the LED 31 appearing to flicker.

[0030] The light axis control unit 41 receives instructions from a higher-level unit (not shown) or signals from a detector (not shown) to control, for example, the light axis of the vehicle lamp. Control of the vertical direction relative to the horizontal direction detects the vehicle's vertical tilt angle relative to the road surface and adjusts the light axis to prevent glare oncoming vehicles. The amount of light axis adjustment may be determined by receiving instructions from a higher-level unit (not shown). Alternatively, the light axis control unit 41 may calculate the amount of light axis adjustment by receiving a signal from a vehicle height detector (not shown) installed in the front-rear direction of the vehicle. Alternatively, a gravity acceleration detector (G sensor) mounted on the circuit board of the vehicle lighting control device 100 may be used instead of the vehicle height detector. Control of the left-right direction relative to the horizontal direction detects the steering angle and adjusts the light axis to illuminate the traveling direction and improve the driver's visibility. The light axis control unit 41 adjusts the light axis by driving the motor 50 according to the amount of light axis adjustment.

[0031] Furthermore, by supplying power to the motor current supply unit 42 from the step-up DC-DC converter unit 22, it is possible to supply a voltage higher than the battery voltage stabilized by constant voltage control to the motor current supply unit 42. Increasing the voltage supplied to the motor current supply unit 42 increases the torque that can be output by the motor 50. This makes it possible to suppress deviation from the target position due to insufficient torque of the motor 50. It is also possible to realize an in-vehicle lamp control device that is less subject to constraints such as the weight and control speed of the in-vehicle lamp that are associated with insufficient torque.

[0032] <Effects> As described above, the automotive lamp control device 100 according to the first embodiment includes a motor control unit 40 that controls a drive signal for driving a motor 50 used in an automotive lamp having a plurality of LEDs 31 connected in series, and a semiconductor light source control unit 20 that controls the lighting of the plurality of LEDs 31. The semiconductor light source control unit 20 includes a step-up DCDC converter unit 22 that boosts the battery voltage to a predetermined voltage that is lower than the total value of the forward voltage drops of the plurality of LEDs 31, a step-down DCDC converter unit 23 that lowers the output voltage of the step-up DCDC converter unit 22, a plurality of FETs 24a and 24b that divide the plurality of LEDs 31 into a plurality of LED groups G1 and G2 and pass current supplied from the step-down DCDC converter unit 23 to each of the LED groups G1 and G2, and a signal processing unit 21 that controls the lighting of the plurality of LEDs 31 by controlling the step-up DCDC converter unit 22, the step-down DCDC converter unit 23, and the plurality of FETs 24a and 24b. The signal processing unit 21 controls each LED 31 to light up at different times for each LED group G1, G2, and the motor control unit 40 receives the output voltage of the boost DC-DC converter unit 22 and controls the drive signal that drives the motor 50.

[0033] Therefore, it is possible to integrate a semiconductor light source control device and a motor control device that have different supply voltages, and to realize a multifunctional and simple in-vehicle lamp control device 100. This makes it possible to reduce the size of the in-vehicle lamp control device 100.

[0034] Furthermore, by drawing power from the step-up DC-DC converter 22 for the motor current supply unit 42, it is possible to supply a voltage higher than the battery voltage, which is stabilized by constant voltage control. This makes the drive voltage of the motor control unit 40 higher than the battery voltage, thereby improving the torque of the motor 50. This makes it possible to suppress deviation from the target position due to insufficient torque of the motor 50.

[0035] Furthermore, there is a trend toward more multi-function and high-performance optical systems for vehicle lighting fixtures, which tend to be heavier. Therefore, the vehicle lighting control device 100 according to the first embodiment is effective when the motor 50 is configured using a stepping motor that may lose synchronization during sudden speed changes or overload.

[0036] <Embodiment 2> Next, an in-vehicle lamp control device 100A according to a second embodiment will be described. Fig. 3 is a configuration diagram of the in-vehicle lamp control device 100A according to the second embodiment. Fig. 4 is a timing chart showing the output voltage of the step-down DC-DC converter unit 23 and the voltages and currents of the LED groups G1, G2, and G3 according to the second embodiment. Here, LED_G3 in Fig. 4 indicates the LED 31 belonging to the LED group G3. Note that in the second embodiment, the same components as those described in the first embodiment are assigned the same reference numerals and descriptions thereof will be omitted.

[0037] In the first embodiment, when integrating a semiconductor light source control device and a motor control device, a specific example has been described in which 16 serially connected LEDs 31 are divided into two LED groups G1 and G2, thereby enabling the output voltage of the step-up DC-DC converter unit 22 to be supplied to the motor current supply unit 42. However, when the 16 LEDs 31 are divided into two LED groups G1 and G2, the setting range of the output voltage of the step-up DC-DC converter unit 22 and the setting range of the output current of the step-down DC-DC converter unit 23 are restricted depending on the number of LEDs to be lit. As a result, the output voltage of the step-up DC-DC converter unit 22 may exceed the withstand voltage of the motor current supply unit 42.

[0038] Conventionally, the motor current supply unit 42 receives battery voltage to drive the motor 50, and therefore the withstand voltage of the motor current supply unit 42 is not very high. Therefore, when the output voltage of the boost DC-DC converter unit 22 becomes high to a certain extent, it is necessary to increase the withstand voltage of the elements constituting the motor current supply unit 42. However, changing to elements with a higher withstand voltage leads to an increase in the size of the circuit and manufacturing costs.

[0039] 3, in the second embodiment, an FET 24c is added to the first embodiment to provide a wider setting range for the output voltage of the step-up DC-DC converter 22. However, in the second embodiment, the 16 LEDs 31 connected in series are divided into three LED groups G1 (5 LEDs), G2 (5 LEDs), and G3 (6 LEDs), just as a specific example, and the total number of LEDs 31, the number of divisions, the division distribution (the number of LEDs belonging to each group), the current value, the duty ratio, and the phase difference between each LED group are adjusted as appropriate according to the required number of LEDs to be lit, the current value, the torque, etc.

[0040] The FETs 24a, 24b, and 24c divide the 16 series-connected LEDs 31 into three LED groups G1, G2, and G3, and control the current flowing through each of the LED groups G1, G2, and G3.

[0041] 3 and 4, by dividing the 16 LEDs 31 into three parts using FETs 24a, 24b, and 24c, it is possible to reduce the voltage required for lighting and lower the set value of the output voltage of the step-up DC-DC converter 22. In this example, the duty cycle of each of the LED groups G1, G2, and G3 is 33%, the phase difference between the LED groups G1, G2, and G3 is 120°, and the base current supplied from the step-down DC-DC converter 23 is 2A.

[0042] Furthermore, the signal processing unit 21 performs duty control on each LED 31 so that the lighting periods of all the LED groups G1, G2, and G3 do not overlap, or so that the total voltage applied to the LEDs 31 when the lighting periods of at least two LED groups overlap is equal to or less than a predetermined constant value. At this time, when the duty ratio of the duty control is small, the amount of current output by the step-down DC-DC converter unit 23 is larger than when the duty ratio is large, thereby ensuring the brightness of the LEDs 31.

[0043] The first and second embodiments are specific examples in which the number of LED groups is divided into two or three, but the number of LED groups is not limited to these. By smoothing the voltage by providing a phase difference to the multiple LED groups and increasing the current value of the current flowing through each LED group to maintain a desired average current, the semiconductor light source control device and the motor control device can be integrated by lowering the output voltage of the step-down DC-DC converter unit 23.

[0044] As described above, the control device 100A for an in-vehicle lamp according to embodiment 2, like the case of embodiment 1, enables integration of a semiconductor light source control device and a motor control device that have different supply voltages, thereby realizing a multifunctional and simple control device 100A for an in-vehicle lamp.

[0045] Furthermore, the signal processing unit 21 performs duty control on each LED 31 so that the lighting periods of all the LED groups G1, G2, and G3 do not overlap, or so that the total voltage applied to the plurality of LEDs 31 when the lighting periods of at least two LED groups overlap is equal to or less than a predetermined constant value, and also increases the amount of current output by the step-down DC-DC converter unit 23 when the duty ratio of the duty control is small compared to when it is large.

[0046] Therefore, even when the lighting periods of at least two of the LED groups G1, G2, and G3 overlap, the brightness of the LEDs 31 can be ensured.

[0047] <Third Embodiment> Next, an in-vehicle lamp control device 100B according to a third embodiment will be described. Fig. 5 is a configuration diagram of the in-vehicle lamp control device 100B according to the third embodiment. Fig. 6 is a diagram showing a timing chart of the voltages of the LED groups G1 and G2, the maximum value of the output voltage of the step-up DC-DC converter unit 22, and the input voltage of the motor current supply unit 42 in the third embodiment. Note that in the third embodiment, the same components as those described in the first and second embodiments are given the same reference numerals, and description thereof will be omitted.

[0048] In the first and second embodiments, the multiple LEDs 31 are divided into two or three LED groups, thereby lowering the voltage required for lighting and lowering the set value of the output voltage of the step-up DC-DC converter unit 22, thereby enabling integration of the semiconductor light source control device and the motor control device. As a result, a voltage that satisfies the following relationship is supplied to the motor control unit 40: battery voltage < maximum instantaneous output voltage of the step-down DC-DC converter unit 23 < output voltage of the step-up DC-DC converter unit 22 < withstand voltage of the motor current supply unit 42. As torque increases, it becomes possible to realize a simple and multifunctional automotive lighting control device 100, 100A.

[0049] However, if an abnormality occurs, for example, if one or both of FET 24a and FET 24b suffer an open circuit failure, all 16 LEDs 31 will light up, and approximately ΣVf=3×16=48V may be required. In this case, the voltage supplied from the step-up DC-DC converter unit 22 to the motor current supply unit 42 will be approximately 48V, and if this exceeds the withstand voltage of the motor current supply unit 42, it will cause a failure. Here, if the 16 LEDs 31 are used as headlights of a vehicle, it is desirable to keep them lit as much as possible to ensure the driver's visibility.

[0050] Therefore, in the third embodiment, in integrating the semiconductor light source control device and the motor control device, a cutoff circuit 60 is provided between the semiconductor light source control unit 20 and the motor control unit 40, and when an abnormality is detected, priority is given to the control of the semiconductor light source control unit 20. Here, the cutoff circuit 60 is composed of a relay, an FET, etc.

[0051] As shown in Figure 5, for example, suppose 16 series-connected LEDs 31 are divided into two LED groups G1 and G2. The forward drop voltage of each LED 31 is approximately 3 V. In other words, if eight LEDs 31 are connected in series in each of the LED groups G1 and G2, the total forward drop voltage will be approximately 24 V.

[0052] 6, the duty ratio of the LED groups G1 and G2 is 50%, and the phase difference is 180°. Therefore, the maximum value of the output voltage of the step-up DC-DC converter unit 22 during normal operation is approximately 24V.

[0053] However, if either or both of FET 24a and FET 24b have an open circuit failure, the on periods of LED groups G1 and G2 overlap. Here, the step-down DC-DC converter 23 performs constant current control, but the output voltage of the step-up DC-DC converter 22 is insufficient to supply the predetermined current. The signal processor 21 detects that the step-down DC-DC converter 23 cannot supply the predetermined current and controls the output voltage of the step-up DC-DC converter 22 to be higher than the predetermined voltage. As a result, the output voltage of the step-up DC-DC converter 22 rises to approximately 48V.

[0054] Therefore, when the signal processing unit 21 detects an abnormality, it sends an abnormality detection signal to the shutdown circuit 60. The shutdown circuit 60 receives this abnormality detection signal and disconnects the semiconductor light source control unit 20 from the motor control unit 40. Specifically, if all 16 LEDs 31 are lit due to a failure or the like, the shutdown circuit 60 disconnects the semiconductor light source control unit 20 from the motor control unit 40, thereby protecting the motor current supply unit 42. The signal processing unit 21 may output an abnormality detection signal when at least one of the FETs 24a and 24b fails, without waiting until the output voltage of the boost DC-DC converter unit 22 exceeds a predetermined voltage. Since failure detection of the FETs 24a and 24b is a conventional technique, a description thereof will be omitted.

[0055] The disconnection of the semiconductor light source control unit 20 and the motor control unit 40 by the cutoff circuit 60 may be triggered by an abnormality detection signal that detects an abnormality in the step-down DC-DC converter unit 23. Alternatively, the output voltage of the step-up DC-DC converter unit 22 may be monitored, and the disconnection may be triggered by an abnormality detection signal that indicates that the output voltage has reached a predetermined cutoff voltage. Furthermore, the number of LED groups is not limited to two, and may be three or more.

[0056] As described above, the automotive lamp control device 100B according to the third embodiment further includes a cutoff circuit 60 provided between the semiconductor light source control unit 20 and the motor control unit 40, and the signal processing unit 21 provides an abnormality detection signal to the cutoff circuit 60 when an abnormality is detected. The cutoff circuit 60 cuts off the connection between the semiconductor light source control unit 20 and the motor control unit 40 when the signal processing unit 21 detects an abnormality or when the output voltage of the boost DC-DC converter unit 22 reaches a predetermined cutoff voltage.

[0057] Therefore, if an abnormality occurs in semiconductor light source control unit 20, priority can be given to the control of semiconductor light source control unit 20. Also, motor current supply unit 42 in motor control unit 40 can be protected.

[0058] Although this disclosure has been described in detail, the above description is illustrative in all respects and is not restrictive. It is understood that countless variations not illustrated can be envisioned.

[0059] It should be noted that the embodiments can be freely combined, and each embodiment can be modified or omitted as appropriate. [Explanation of symbols]

[0060] 20 semiconductor light source control unit, 21 signal processing unit, 22 step-up DCDC converter unit, 23 step-down DCDC converter unit, 24a, 24b, 24c FET, 31 LED, 40 motor control unit, 50 motor, 60 cutoff circuit, 100, 100A, 100B automotive lighting fixture control device, G1, G2, G3 LED group.

Claims

1. a motor control unit that controls a drive signal that drives a motor used in an in-vehicle lamp having a plurality of semiconductor light sources connected in series; a semiconductor light source control unit that controls the lighting of the plurality of semiconductor light sources, The semiconductor light source control unit a booster unit that boosts the battery voltage to a predetermined voltage that is lower than the total value of forward voltage drops of the semiconductor light sources; a step-down unit that steps down the output voltage of the step-up unit; a plurality of switching units that divide the plurality of semiconductor light sources into a plurality of groups and cause the current supplied from the step-down unit to flow to each of the groups; a signal processing unit that controls the step-up unit, the step-down unit, and the plurality of switching units to control the lighting of the plurality of semiconductor light sources, the signal processing unit controls the semiconductor light sources to be turned on at different times for each of the groups, The motor control unit receives the output voltage of the boost unit and controls the drive signal that drives the motor.

2. 2. The control device for an automotive lighting fixture according to claim 1, wherein the signal processing unit performs duty control on each of the semiconductor light sources so that the lighting periods of all of the groups do not overlap, or so that the sum of voltages applied to the plurality of semiconductor light sources when the lighting periods of at least two of the groups overlap is equal to or less than a predetermined constant value, and increases the amount of current output by the step-down unit when the duty ratio of the duty control is small compared to when it is large.

3. a blocking circuit provided between the semiconductor light source control unit and the motor control unit; the signal processing unit provides an abnormality detection signal to the interruption circuit when an abnormality is detected, 2. The control device for an automotive lighting fixture according to claim 1, wherein the cutoff circuit disconnects the semiconductor light source control unit from the motor control unit when the signal processing unit detects the abnormality or when the output voltage of the boost unit reaches a predetermined cutoff voltage.

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