Leveling control device and lighting system

Abstract

The present invention comprises a leveling actuator (114) which is for optical axis adjustment and is provided in a head lamp (110). This leveling control device (200) controls the leveling actuator (114). An operation unit (210) outputs a control signal (SCTRL) that changes according to control characteristics defined by a broken line with respect to a slope (θ) of a vehicle body in the longitudinal direction of the vehicle body. An output stage (220) generates an output voltage (SOUT) in response to the control signal (SCTRL).

Description

[Technical Field]

[0001] This disclosure relates to vehicle lighting equipment. [Background technology]

[0002] The beam pattern of a car's headlights is regulated by law to prevent glare to surrounding traffic. The front-to-rear tilt of the vehicle body changes depending on the number of passengers and the weight of the cargo. This changes the angle between the ground and the optical axis of the headlight, which in turn changes the vertical illumination range of the headlight. If the illumination range shifts upward, it may cause glare, and if it shifts downward, the illumination range in front of the vehicle narrows.

[0003] To compensate for changes in the optical axis of the headlights due to changes in the front-to-rear tilt of the vehicle body, a leveling actuator is built into the headlight. There is a technology called auto-leveling that automatically controls the leveling actuator according to the tilt of the vehicle body. Auto-leveling acquires the front-to-rear tilt of the vehicle body using sensors installed on the vehicle body, and corrects the optical axis of the lighting unit in the headlight using the actuator to counteract that tilt. [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Conventional auto-leveling systems are not perfect and there is room for improvement. This disclosure is made in such circumstances, and one of its exemplary purposes is to provide a control device and vehicle lighting equipment that can achieve accurate optical axis alignment over a wide range of vehicle tilt angles. [Means for solving the problem]

[0005] A part of this disclosure relates to a leveling control device for controlling an actuator for adjusting the optical axis of a headlamp. The leveling control device includes a calculation unit that outputs a control signal that changes according to a control characteristic defined by a piece line in response to the longitudinal tilt of the vehicle body, and an output stage that generates an output voltage corresponding to the control signal.

[0006] Another aspect of the present disclosure is also a leveling control device. This leveling control device includes a calculation unit that outputs a control signal that changes according to a control characteristic defined by a piecewise linear function for a sensor value correlated with the longitudinal tilt of the vehicle body, and an output stage that generates an output voltage corresponding to the control signal.

[0007] Furthermore, any combination of the above components, or any substitution of components or expressions between methods, apparatus, systems, etc., are also valid as embodiments of the present invention or this disclosure. Moreover, the description in this section (means for solving the problem) does not describe all the indispensable features of the present invention, and therefore, subcombinations of these described features may also constitute the present invention. [Effects of the Invention]

[0008] According to one aspect of this disclosure, accurate optical axis alignment can be achieved over a wide range of vehicle body inclination angles. [Brief explanation of the drawing]

[0009] [Figure 1] This is a block diagram of the lighting system according to Embodiment 1. [Figure 2] This is a block diagram showing the configuration of the leveling control device according to Embodiment 1. [Figure 3] This is a diagram illustrating the control characteristics. [Figure 4] This figure shows an example of the control signal SCTRL. [Figure 5] This figure shows an example of the output stage configuration corresponding to the control signal SCTRL in Figure 4. [Figure 6]This figure shows the relationship between the tilt angle θ and the control signal SCTRL in the comparative technique. [Figure 7] Figure 7(a) shows an example of ideal input / output characteristics and realistic input / output characteristics of the output stage, Figure 7(b) shows the control characteristics of the lighting system relating to the comparative technology, and Figure 7(c) shows the control characteristics of the lighting system relating to Embodiment 1. [Figure 8] This is a block diagram of a leveling control device according to Embodiment 2. [Figure 9] This figure illustrates an example of the control characteristics in Embodiment 2. [Figure 10] This is a block diagram of a leveling control device according to Embodiment 3. [Figure 11] This figure illustrates an example of the control characteristics in Embodiment 3. [Figure 12] This is a block diagram of the leveling control device according to Embodiment 4. [Modes for carrying out the invention]

[0010] (Summary of the embodiment) This section outlines some exemplary embodiments of the present disclosure. This outline is intended to provide a basic understanding of the embodiments and to simplify some concepts of one or more embodiments, serving as a prelude to the more detailed descriptions that follow. It does not limit the scope of the invention or disclosure. Furthermore, this outline is not a comprehensive overview of all possible embodiments and does not limit the essential components of the embodiments. For convenience, "one embodiment" may refer to one or more embodiments (examples or variations) disclosed herein.

[0011] A leveling control device according to one embodiment controls an actuator for adjusting the optical axis provided in the headlamp. The leveling control device includes a calculation unit that outputs a control signal that changes according to control characteristics defined by a piece line in response to the longitudinal tilt of the vehicle body, and an output stage that generates an output voltage corresponding to the control signal.

[0012] A leveling control device according to one embodiment includes a calculation unit that outputs a control signal that changes according to control characteristics defined by a piecewise linear function for a sensor value correlated with the inclination of the vehicle body in the longitudinal direction, and an output stage that generates an output voltage corresponding to the control signal.

[0013] The actual displacement of the actuator in response to tilt is affected by the input / output characteristics of the output stage and the input / output characteristics of the actuator itself. Therefore, if the control signal is changed linearly in response to tilt, the optical axis can be controlled well within a certain range of tilt angles, but when the tilt angle falls outside that range, the optical axis may deviate from the optimal value. With this configuration, by defining the control characteristics, which use tilt as input and control signal as output, as a piecewise linear function, accurate optical axis alignment can be achieved over a wide range of tilt angles.

[0014] In one embodiment, the control signal is a pulse signal, and the value of the control signal may be the duty cycle of the pulse signal. The output stage may include a filter for smoothing the pulse signal.

[0015] In one embodiment, the calculation unit may change the control characteristics according to the temperature. When the ideal control characteristics change as the temperature changes, the effect of temperature fluctuations can be canceled out.

[0016] In one embodiment, the calculation unit may define multiple control characteristics corresponding to a plurality of predetermined temperatures. The calculation unit may generate a control signal at any temperature other than the plurality of predetermined temperatures by interpolating two control signals calculated based on two control characteristics defined for two predetermined temperatures that straddle that temperature.

[0017] In one embodiment, the calculation unit may define multiple control characteristics corresponding to a plurality of predetermined temperatures. The calculation unit may generate control characteristics at any temperature other than the plurality of predetermined temperatures by interpolating two control characteristics defined for two predetermined temperatures that straddle that temperature.

[0018] In one embodiment, the multiple predetermined temperatures may be room temperature, the maximum temperature, and the minimum temperature.

[0019] In one embodiment, the calculation unit may change its control characteristics in accordance with the power supply voltage. When the power supply voltage changes, the effects of power supply voltage fluctuations can be canceled out if the input / output characteristics of the output stage change.

[0020] In one embodiment, the calculation unit may define multiple control characteristics corresponding to a plurality of predetermined power supply voltages. The calculation unit may generate a control signal for any power supply voltage other than the plurality of predetermined power supply voltages by interpolating two control signals calculated based on two control characteristics defined for two predetermined power supply voltages that straddle the power supply voltage.

[0021] In one embodiment, the calculation unit may define multiple control characteristics corresponding to a plurality of predetermined power supply voltages. The calculation unit may generate control characteristics for any power supply voltage other than the plurality of predetermined power supply voltages by interpolating two control characteristics defined for two predetermined power supply voltages that straddle the power supply voltage.

[0022] A lighting system according to one embodiment includes a sensor capable of detecting the tilt of the vehicle body, a headlamp including an actuator for adjusting the optical axis, and one of the above-mentioned leveling control devices that outputs an output voltage to the actuator corresponding to the tilt of the vehicle body based on the output of the sensor.

[0023] In one embodiment, the leveling control device may change its control characteristics according to the temperature.

[0024] In one embodiment, the leveling control device may change its control characteristics in accordance with the power supply voltage.

[0025] (Embodiment) Preferred embodiments will be described below with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing will be denoted by the same reference numerals, and redundant descriptions will be omitted where appropriate. Furthermore, the embodiments are illustrative and not limiting, and not all features or combinations thereof described in the embodiments are necessarily essential to the disclosure.

[0026] In this specification, "member A connected to member B" includes not only cases where member A and member B are directly connected physically, but also cases where member A and member B are indirectly connected via other members that do not substantially affect their electrical connection or impair the functions or effects produced by their combination.

[0027] Similarly, "the state in which member C is provided between member A and member B" includes not only cases where member A and member C, or member B and member C, are directly connected, but also cases where they are indirectly connected via other members that do not substantially affect their electrical connection state or impair the functions or effects produced by their combination.

[0028] (Embodiment 1) Figure 1 is a block diagram of the lighting system 100 according to Embodiment 1. The lighting system 100 is a headlamp mounted on an automobile that illuminates the field of view in front of the vehicle. The tilt angle in the front-rear direction of an automobile changes according to the front-rear weight balance. The tilt angle in the front-rear direction is the rotation around the horizontal axis extending from left to right of the vehicle body, i.e., the pitch angle. The lighting system 100 has a function (auto-leveling function) that automatically adjusts the optical axis in the pitch direction of the headlamp according to the tilt angle of the vehicle body.

[0029] The system comprises a headlamp body 110, a sensor 120, and a leveling control device 200. The headlamp body 110 is installed at a predetermined position on the front of the vehicle. The headlamp 110 includes a lighting unit 112 and a leveling actuator 114. The lighting unit 112 is an integrated unit comprising a light-emitting element 116, an optical system 118 such as a mirror or lens, and a bracket 119. The lighting unit 112 is supported on the housing of the headlamp body 110 so as to be rotatable in the pitch direction. The leveling actuator 114 receives an output signal S from the leveling control device 200. OUT Accordingly, the position of the lighting unit 112 in the pitch direction is controlled.

[0030] Sensor 120 is provided to detect the inclination of the vehicle body in the longitudinal direction. In one embodiment, sensor 120 includes a rear ride height sensor provided near the rear suspension of the vehicle body to detect the sag of the rear of the vehicle body. In another embodiment, in addition to the rear ride height sensor, sensor 120 includes a front ride height sensor provided near the front suspension of the vehicle body to detect the sag of the front of the vehicle body. Sensor 120 receives a sensor signal S based on the output of the ride height sensor. SNS Outputs.

[0031] The leveling control device 200 receives the sensor signal S generated by the sensor 120. SNS The leveling of the headlamp 110 is automatically controlled accordingly. The leveling control device 200 is installed inside the vehicle, for example, at the driver's feet.

[0032] The vehicle body's longitudinal tilt angle θ is calculated, and a drive signal S is sent to the leveling actuator 114 so that the optical axis of the headlamp 110 is at an appropriate angle φ relative to the calculated tilt angle θ. OUT Generates.

[0033] The leveling control device 200 includes a calculation unit 210 and an output stage 220. The calculation unit 210 receives the sensor signal S SNS Based on this, the vehicle body's longitudinal tilt angle θ is calculated. The calculation unit 210 receives the vehicle body's tilt angle θ and the control signal SCTRL The control characteristics that define the correspondence relationship are maintained, and according to this control characteristic, the tilt angle θ and the corresponding control signal S CTRL are generated. The control signal S CTRL is a signal that defines the magnitude of the output signal S O UT to be supplied to the leveling actuator 114.

[0034] The arithmetic unit 210 is composed of, for example, a microcontroller, and its operations and functions are defined by a software program executed by the microcontroller.

[0035] When the leveling control device 200 is arranged in the passenger compartment as described above, it is necessary to transmit the control signal S CTRL to the position of the headlamp 110 far from it. However, since the amplitude of the signal that can be generated by the microcontroller, which is the arithmetic unit 210, is weak, it is difficult to transmit it to the headlamp 110 as it is. Therefore, an output stage 220 for amplifying the control signal S CTRL is provided at the subsequent stage of the arithmetic unit 210. The control signal S CTRL amplified by the output stage 220 is supplied to the headlamp 110 as the output signal S OUT .

[0036] The above is the basic configuration of the lamp system 100. Next, the specific configuration of the leveling control device 200 will be described.

[0037] FIG. 2 is a block diagram showing the configuration of the leveling control device 200 according to Embodiment 1. The arithmetic unit 210 includes a tilt angle calculation unit 212 and a control signal generation unit 214. As described above, since the arithmetic unit 210 is implemented by a combination of a microcontroller and a software program, the sub-blocks (212, 214) in the arithmetic unit 210 merely indicate functional elements or processing units realized by the arithmetic unit 210.

[0038] The tilt angle calculation unit 212 is the sensor signal S SNSBased on this, the vehicle body tilt angle θ is calculated. Sensor signal S SNS The relationship between the actual tilt angle θ and the lighting system 100 differs for each vehicle body on which it is installed. Therefore, during the vehicle body manufacturing process, vehicle-specific parameters are written to the microcontroller's non-volatile memory, and the correct input / output characteristics of the tilt angle calculation unit 212 are defined.

[0039] The control signal generation unit 214 generates a control signal S with respect to the tilt angle θ. CTRL The control signal generation unit 214 maintains control characteristics defined by a polyline for the vehicle body's longitudinal tilt angle θ, and based on these control characteristics, the control signal generation unit 214 generates a control signal S corresponding to the tilt angle θ. CTRL Generates.

[0040] Figure 3 illustrates the control characteristics. The horizontal axis represents the tilt angle θ, and the vertical axis represents the control signal S. CTRL The value v is normalized within the actuator's control range and expressed as 0-100%. The specific method by which the control signal generation unit 214 maintains the control characteristics is not particularly limited. For example, the control signal generation unit 214 may maintain multiple sets of coordinates (θ,v) of the vertices of the polyline. That is, sets of θ1, θ2, θ3, ... and their corresponding v, v2, v3... are maintained. The θ generated by the tilt angle calculation unit 212 is θ i <θ<θ i+1 If that is the case, the control signal S corresponding to θ CTRL The value v can be calculated from equation (1). v={v i × (θ) i+1 -θ)+v i+1 ×(θ-θ i )} / (θ i+1 -θ i ) …(1)

[0041] Alternatively, the control signal generation unit 214 may hold the equations for each of the multiple straight lines that make up the polyline. Specifically, θ i <θ<θ i+1 The straight line in the region is v=a i θ+b i …(2) It can be expressed in the form of θ. Therefore, θ i <θ<θ i+1 The value of the control signal v corresponding to θ can be calculated from equation (2).

[0042] Figure 4 shows the control signal S CTRL This figure shows an example of the control signal S. CTRL This is a pulse signal with a constant period Tp (frequency), and its duty cycle is the control signal S. CTRL This represents the value v, that is, the control signal S. CTRL This can be a PWM (Pulse Width Modulation) signal. Control signal S CTRL pulse width T ON and control signal S CTRL The relationship given by equation (3) holds between the values ​​of v. T ON =v × Tp …(3)

[0043] Figure 5 shows the control signal S in Figure 4. CTRL This figure shows an example configuration of the output stage 220 corresponding to the power supply voltage V. The output stage 220 includes an inverter circuit 222 and a filter 224. The inverter circuit 222 receives the power supply voltage V. DD The signal is supplied. The inverter circuit 222 receives the control signal S, which is a PWM signal. CTRL It switches accordingly. Filter 224 is a low-pass filter, which smooths the output signal of the inverter circuit 222 and the output signal S OUT It generates the output signal S. OUT The voltage level V is 0 to V DD Between, control signal S CTRL It changes in proportion to the value v (i.e., the duty cycle), and equation (4) holds. V = v × V DD …(4)

[0044] The above describes the configuration of the lighting system 100. The technical significance and advantages of the lighting system 100 according to Embodiment 1 will become clear when compared with the comparative technology. Therefore, the comparative technology will be described first.

[0045] Figure 6 shows the tilt angle θ and the control signal S in the comparative technique. CTRL This diagram shows the relationship between the input / output characteristics of the output stage 220, i.e., the control signal S. CTRL Value v and output signal S OUT The relationship V can ideally be expressed as a linear function. In the comparative technique, assuming the ideal input / output characteristics of the output stage 220, the control characteristics of the arithmetic unit 210 are defined by a single straight line (i.e., a linear function).

[0046] The inventors of this invention have examined comparative technologies and come to recognize the following problems: It is difficult to design and manufacture the output stage 220 so that its input / output characteristics are perfectly linear, and in reality, the input / output characteristics of the output stage 220 are nonlinear. Figure 7(a) shows an example of the ideal input / output characteristics of the output stage 220 and an example of the realistic input / output characteristics. Note that this example exaggerates the nonlinearity and may differ from the actual characteristics. For example, when the output stage 220 is configured as shown in Figure 5, the deviation from the ideal characteristics becomes large in the region where the duty cycle is near 0% (i.e., the region where v is small) and in the region where the duty cycle is close to 100% (i.e., the region where v is large). In other words, accurate optical axis control can only be achieved within a narrow range of vehicle body tilt angles.

[0047] Figure 7(b) shows the control characteristics of the lighting system relating to the comparative technology. These control characteristics are a combination of the input / output characteristics of the realistic output stage 220 in Figure 7(a) and the control characteristics of the calculation unit 210 relating to the comparative technology. The control characteristics of the lighting system are expressed with the tilt angle θ as input and the control angle φ of the optical axis of the headlamp 110 as output. In the comparative technology, the control angle φ of the optical axis does not change linearly with respect to the tilt angle θ, which can lead to problems such as the optical axis pointing too far upward relative to the horizontal, causing glare, or conversely, the optical axis pointing too far downward relative to the horizontal, resulting in a darkened field of view.

[0048] Figure 7(c) shows the control characteristics of the lighting system 100 according to Embodiment 1. These control characteristics are obtained by combining the input / output characteristics of the realistic output stage 220 in Figure 7(a) with the control characteristics of the calculation unit 210 according to Embodiment 1. In Embodiment 1, since the control characteristics of the output stage 220 are defined by a piecewise curve, the control angle φ of the optical axis can be changed linearly with respect to the tilt angle θ.

[0049] In other words, according to Embodiment 1, by defining the control characteristics in the calculation unit 210 with a piecewise linear function, the nonlinearity of the input / output characteristics of the output stage 220 can be compensated for, thereby making it possible to maintain a substantially constant relationship between the optical axis and the horizontal regardless of the vehicle body tilt angle θ. In other words, compared to the comparative technology, an accurate optical axis can be achieved over a wider range of vehicle body tilt angles.

[0050] (Embodiment 2) Figure 8 is a block diagram of the leveling control device 200A according to Embodiment 2. In addition to the leveling control device 200 of Figure 2, the leveling control device 200A includes a temperature sensor 230. The temperature sensor 230 is positioned to detect the temperature of the output stage 220 or its ambient temperature. The temperature sensor 230 can be, for example, a thermistor or a thermocouple.

[0051] The output of the temperature sensor 230 is digitized. The control signal generation unit 214A changes the control characteristics according to the temperature TEMP.

[0052] Figure 9 illustrates an example of control characteristics in Embodiment 2. In Embodiment 2, multiple control characteristics are defined corresponding to multiple predetermined temperatures. In this example, three predetermined temperatures (T2, T2, T3) are defined: room temperature (25°C), maximum temperature (80°C, 110°C, 120°C, etc.), and minimum temperature (-30°C). 3, The control characteristics are defined for T1. Each control characteristic is defined as a piecewise curve, as described in Embodiment 1.

[0053] In one embodiment, the control signal generation unit 214A generates the control signal S at an arbitrary temperature T other than the plurality of predetermined temperatures T1, T2, and T3 CTRL by interpolating the values v1 and v2 of two control signals S calculated based on two control characteristics defined for two predetermined temperatures sandwiching the temperature T i , T i +1 CTRL CTRL . For example, when T1 < T < T2, based on the control characteristic for T1, the value v1 of the control signal S corresponding to the current θ is calculated. Similarly, based on the control characteristic for T2, the value v2 of the control signal S corresponding to the current θ is calculated

[0054] . Then, the value v of the final control signal S CTRL CTRL CTRL can be calculated from

[0055] v = {v1 × (T2 - T) + v2 × (T - T1)} / (T2 - T1) CTRL .

[0056]

[0057] In one embodiment, the control signal generation unit 214A may generate the control characteristic at an arbitrary temperature T other than the plurality of predetermined temperatures T1, T2, and T3 by interpolating two control characteristics defined for two predetermined temperatures sandwiching the temperature T. Then, based on the control characteristic generated by interpolation, the value v of the control signal S corresponding to the current tilt angle θ may be calculated CTRL .

[0057] The above is the configuration of the leveling control device 200A. According to this leveling control device 200A, when the temperature dependence of the input / output characteristics of the output stage 220 is large, the influence of temperature can be reduced to approach preferable control characteristics

[0058] (Embodiment 3) FIG. 10 is a block diagram of a leveling control device 200B according to Embodiment 3. In Embodiment 3, in the leveling control device 200B, the power supply voltage V supplied to the output stage 220 DDis reflected in the control characteristics of the control signal generation unit 214B. That is, the control signal generation unit 214B changes the control characteristics based on the power supply voltage V DD of the output stage 220.

[0059] FIG. 11 is a diagram for explaining an example of the control characteristics in Embodiment 3. In Embodiment 3, a plurality of control characteristics are defined corresponding to a plurality of power supply voltages V DD1 , V DD2 , V DD3 . For example, the power supply voltages can be defined as V DD1 = 10V, V DD2 = 13.5V, V DD3 = 16V. Each control characteristic is defined as a broken line in the same manner as described in Embodiment 1.

[0060] In one embodiment, the control signal generation unit 214B calculates the control signal S DD1 , V DD2 , V DD3 at an arbitrary power supply voltage V DD other than the above by interpolating the values v1 and v2 of two control signals S CTRL calculated based on two control characteristics defined for two voltage levels V D D straddling the power supply voltage V DDi , V DDi+1 . CTRL For example, when V DD2 <V DD <V DD3 <V DD2 <V CTRL <V DD3 <V CTRL <V CTRL <V DD3 <V DD DD DD2 DD3 DD2 DD1 v = {v2×(V DD3 - V DD) + v3×(V DD - V DD2 ) / (V DD3 - V DD2 ) It may be calculated from

[0063] In one embodiment, the control signal generation unit 214B may generate the control characteristics at an arbitrary power supply voltage V other than a plurality of predetermined power supply voltages V DD1 , V DD 2, V DD3 by interpolating two control characteristics defined for two predetermined power supply voltages sandwiching the power supply voltage V DD . Then, based on the control characteristics generated by interpolation, the value v of the control signal S DD corresponding to the current tilt angle θ may be calculated. CTRL

[0064] The above is the configuration of the leveling control device 200B. According to this leveling control device 200B, when the input-output characteristics of the output stage 220 have a large power supply voltage dependency, the influence of power supply voltage fluctuations can be reduced, and it can approach preferable control characteristics.

[0065] (Embodiment 4) FIG. 12 is a block diagram of a leveling control device 200C according to Embodiment 4. In Embodiment 4, in the leveling control device 200C, both the temperature of the output stage 220 and the power supply voltage V DD supplied to the output stage 220 are reflected in the control characteristics in the control signal generation unit 214B. That is, the control signal generation unit 214C changes the control characteristics based on the temperature T of the output stage 220 and the power supply voltage V DD .

[0066] For example, for each of a matrix-like M×N combinations of a plurality of M predetermined temperatures T and a plurality of N predetermined power supply voltages V DD , the control characteristics are defined by a broken line. The control signal generation unit 214C calculates the value of the control signal S DD corresponding to the current temperature T and power supply voltage V CTRL by interpolation processing.

[0067] (modified version) The embodiments described above are illustrative, and it will be understood by those skilled in the art that various modifications are possible in combinations of their components and processing steps. Such modifications will be described below.

[0068] (Variation 1) Sensor 120 may include an acceleration sensor (G sensor). In this case, sensor 120 may be mounted on the leveling control device 200 rather than on the vehicle side. The calculation unit 210 calculates the longitudinal tilt (inclination angle) θ of the vehicle body based on the output of the acceleration sensor.

[0069] (Modification 2) In this embodiment, the nonlinearity of the input / output characteristics of the output stage 220 was compensated by defining the control characteristics of the calculation unit 210 with a piecewise curve. However, the nonlinearity in the lighting system 100 may also be caused by parts other than the output stage 220, specifically the input / output characteristics of the leveling actuator 114 or the mechanism that rotates the lighting unit 112. Even in this case, the piecewise curve can be defined so that the angle φ of the optical axis, which is the final output, and the inclination angle θ of the vehicle body satisfy the desired relationship.

[0070] (Variation 3) Control signal S is the output of the arithmetic unit 210. CTRL The form and configuration of the output stage 220 are not limited to those described in the embodiments. If the microcontroller constituting the arithmetic unit 210 includes a D / A converter, the control signal S CTRL This can be a DC analog voltage. In this case, the output stage 220 can be configured as a linear amplifier.

[0071] Although this disclosure has been described using specific terminology based on embodiments, embodiments merely illustrate the principles and applications of this disclosure, and many modifications and changes in arrangement are permitted in embodiments, provided they do not deviate from the spirit of this disclosure as defined in the claims. [Industrial applicability]

[0072] This disclosure relates to vehicle lighting equipment. [Explanation of Symbols]

[0073] 100 Lighting System 110 Headlights 112 Lighting Unit 114 Leveling Actuator 120 sensors 200 Leveling Control Device 210 Arithmetic section 212 Tilt angle calculation section 214 Control signal generation unit 220 output stages 222 Inverter Circuit 230 Temperature Sensor

Claims

1. A leveling control device that controls an actuator for adjusting the optical axis provided in a headlamp, A calculation unit takes the vehicle's front-to-rear tilt angle as input and outputs a control signal that changes according to a control characteristic defined by a polyline with respect to the tilt angle. An output stage that generates an output voltage corresponding to the aforementioned control signal, A leveling control device characterized by comprising:

2. The calculation unit is: An inclination angle calculation unit calculates the inclination angle based on sensor values ​​that correlate with the inclination of the vehicle body in the front-rear direction, A control signal generation unit that outputs the control signal which changes according to the control characteristics defined by a piecewise curve with respect to the aforementioned tilt angle, The leveling control device according to claim 1, characterized by including

3. The control signal is a pulse signal, and the value of the control signal is the duty cycle of the pulse signal. The leveling control device according to claim 1 or 2, characterized in that the output stage includes a filter for smoothing the pulse signal.

4. The leveling control device according to claim 1 or 2, characterized in that the calculation unit changes the control characteristics according to the temperature.

5. The calculation unit has defined a plurality of control characteristics corresponding to a plurality of predetermined temperatures. The leveling control device according to claim 1 or 2, characterized in that the calculation unit generates a control signal at any temperature other than the plurality of predetermined temperatures by interpolating two control signals calculated based on two control characteristics defined for two predetermined temperatures that straddle the temperature.

6. The calculation unit has defined a plurality of control characteristics corresponding to a plurality of predetermined temperatures. The leveling control device according to claim 1 or 2, characterized in that the calculation unit generates control characteristics at any temperature other than the plurality of predetermined temperatures by interpolating two control characteristics defined for two predetermined temperatures that straddle that temperature.

7. The leveling control device according to claim 1 or 2, characterized in that the calculation unit changes the control characteristics according to the power supply voltage.

8. The calculation unit has defined multiple control characteristics corresponding to multiple predetermined power supply voltages, The leveling control device according to claim 1 or 2, characterized in that the calculation unit generates a control signal for any power supply voltage other than the plurality of predetermined power supply voltages by interpolating two control signals calculated based on two control characteristics defined for two predetermined power supply voltages that straddle the said power supply voltage.

9. The calculation unit has defined multiple control characteristics corresponding to multiple predetermined power supply voltages, The leveling control device according to claim 1 or 2, characterized in that the calculation unit generates control characteristics at any power supply voltage other than the plurality of predetermined power supply voltages by interpolating two control characteristics defined for two predetermined power supply voltages that straddle the said power supply voltage.

10. A leveling control device for controlling an actuator for adjusting the optical axis provided in a headlamp, A calculation unit that outputs a control signal that changes according to a control characteristic defined by a piecewise linear function, based on sensor values ​​that correlate with the vehicle's longitudinal tilt, An output stage that generates an output voltage corresponding to the aforementioned control signal, Equipped with, The calculation unit has defined a plurality of control characteristics corresponding to a plurality of predetermined temperatures. The leveling control device is characterized in that the calculation unit generates a control signal at any temperature other than the plurality of predetermined temperatures by interpolating two control signals calculated based on two control characteristics defined for two predetermined temperatures that straddle the temperature in question.

11. A leveling control device for controlling an actuator for adjusting the optical axis provided in a headlamp, A calculation unit that outputs a control signal that changes according to a control characteristic defined by a piecewise linear function, based on sensor values ​​that correlate with the vehicle's longitudinal tilt, An output stage that generates an output voltage corresponding to the aforementioned control signal, Equipped with, The calculation unit has defined a plurality of control characteristics corresponding to a plurality of predetermined temperatures. The leveling control device is characterized in that the calculation unit generates control characteristics at any temperature other than the plurality of predetermined temperatures by interpolating two control characteristics defined for two predetermined temperatures that straddle that temperature.

12. A leveling control device for controlling an actuator for adjusting the optical axis provided in a headlamp, A calculation unit that outputs a control signal that changes according to a control characteristic defined by a piecewise linear function, based on sensor values ​​that correlate with the vehicle's longitudinal tilt, An output stage that generates an output voltage corresponding to the aforementioned control signal, Equipped with, The calculation unit has defined multiple control characteristics corresponding to multiple predetermined power supply voltages, The leveling control device is characterized in that the calculation unit generates a control signal for any power supply voltage other than the plurality of predetermined power supply voltages by interpolating two control signals calculated based on two control characteristics defined for two predetermined power supply voltages that straddle the said power supply voltage.

13. A leveling control device for controlling an actuator for adjusting the optical axis provided in a headlamp, A calculation unit that outputs a control signal that changes according to a control characteristic defined by a piecewise linear function, based on sensor values ​​that correlate with the vehicle's longitudinal tilt, An output stage that generates an output voltage corresponding to the aforementioned control signal, Equipped with, The calculation unit has defined multiple control characteristics corresponding to multiple predetermined power supply voltages, The leveling control device is characterized in that the calculation unit generates control characteristics at any power supply voltage other than the plurality of predetermined power supply voltages by interpolating two control characteristics defined for two predetermined power supply voltages that straddle the said power supply voltage.

14. A sensor is provided to detect the tilt of the vehicle body, A headlamp including an actuator for adjusting the optical axis, A leveling control device according to any one of claims 1, 2, 10, 11, 12, or 13, which outputs an output voltage to the actuator corresponding to the tilt of the vehicle body based on the output of the sensor, A lighting system characterized by having the following features.

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