Vehicle headlights

Abstract

A vehicle headlight (1) includes a first light source unit (20), a second light source unit (40), and a control unit (CO), wherein the control unit (CO) moves at least the upper edge of a low beam light distribution pattern (101) upward when performing temperature derating on the second light source unit (40) on the basis of the temperature of the second light source unit (40) in a state where a high beam light distribution pattern (105) is formed.

Description

Technical Field

[0001] The present invention relates to a vehicle headlamp.

Background Art

[0002] A vehicle headlamp may include a light source unit including a light emitting part such as an LED (Light Emitting Diode) and a circuit board on which the light emitting part is mounted. In such a vehicle headlamp, when the temperature of the light source unit becomes equal to or higher than a predetermined value, the duty ratio of the light emitting part may be decreased according to the temperature. When the duty ratio is decreased, the amount of heat generated from the light emitting part is reduced, and thus the light emitting part is protected from heat. Such control of the duty ratio is called temperature derating, and Patent Document 1 below discloses a lighting fixture that performs temperature derating.

[0003]

Patent Document 1

Summary of the Invention

[0004] In a vehicle headlamp, a high beam light distribution pattern may be formed by a low beam light distribution pattern and an additional light distribution pattern added to the low beam light distribution pattern. The additional light distribution pattern tends to be darker at the upper and lower edge sides than at the center side. When temperature derating is performed on a light emitting part that emits light forming the additional light distribution pattern in a state where the high beam light distribution pattern is formed, the center side of the additional light distribution pattern becomes darker, and accordingly, the lower edge side of the additional light distribution pattern also becomes darker. When the additional light distribution pattern becomes darker in this way, the visibility ahead may decrease.

[0005] Therefore, an object of the present invention is to provide a vehicle headlamp that can suppress a decrease in visibility ahead when temperature derating is performed.

[0006] To achieve the above objective, the vehicle headlight of the present invention comprises a first light source unit that emits first light to the front of the vehicle to form a low beam light distribution pattern, a second light source unit that emits second light to form an additional light distribution pattern which is added to the low beam light distribution pattern to form a high beam light distribution pattern, and a control unit, wherein when the control unit performs temperature derating on the second light source unit based on the temperature of the second light source unit while the high beam light distribution pattern is being formed, it moves at least the upper edge of the low beam light distribution pattern upward.

[0007] According to the above configuration, by moving the upper edge of the low beam's light distribution pattern upward, the upper edge of the low beam's light distribution pattern can brighten the lower edge of the additional light distribution pattern, which would otherwise be darkened by temperature derating. Therefore, a decrease in forward visibility can be suppressed.

[0008] Furthermore, when the control unit performs the temperature derating on the second light source, it may move the upper edge of the low beam's light distribution pattern upward before performing the temperature derating.

[0009] Conversely to the above configuration, if the upper edge of the low beam's light distribution pattern moves upward after temperature derating, two peaks may be formed in the intensity distribution of the high beam's light distribution pattern between the time of temperature derating and the time the upper edge of the low beam's light distribution pattern moves, due to the region with the highest intensity in the low beam's light distribution pattern and the region with the highest intensity in the additional light distribution pattern. When two peaks are formed, the region corresponding to the intensity dip located between the two peaks in the high beam's light distribution pattern tends to be darker than the regions on either side of the dip. If the region corresponding to the dip is located in the driver's line of sight, the driver may perceive that the area in their line of sight is darker than elsewhere, potentially reducing visibility. However, in the above configuration, since the upper edge of the low beam's light distribution pattern moves upward before temperature derating, the formation of a dip between the two peaks can be suppressed. Therefore, the reduction in visibility can be suppressed compared to the case where a dip is formed.

[0010] Furthermore, when the control unit performs the temperature derating on the second light source, it may increase the amount of movement of the upper edge of the low beam's light distribution pattern according to the vehicle's travel speed.

[0011] According to the above configuration, when the vehicle is traveling at high speed, the amount of movement of the upper end increases compared to when the vehicle is traveling at low speed, allowing the driver to see far ahead in a brighter view, potentially improving safety.

[0012] Furthermore, when the control unit performs the temperature derating on the second light source, it may move at least the upper edge of the additional light distribution pattern upward.

[0013] When the control unit performs temperature derating on the second light source, the central side of the additional light distribution pattern becomes darker than before temperature derating, and the upper edge becomes even darker. When the upper edge becomes even darker, the driver is more likely to feel a sense of unease as if the upper edge has lowered. In the above configuration, when the control unit performs temperature derating on the second light source, it moves at least the upper edge of the additional light distribution pattern upward. When the upper edge of the additional light distribution pattern moves upward, the area in the driver's line of sight becomes brighter when the driver is viewing distant objects, which can suppress the driver from feeling a sense of unease as if the upper edge has lowered, and thus can suppress a decrease in visibility.

[0014] Furthermore, when the control unit performs the temperature derating on the second light source, it may move the lower edge of the additional light distribution pattern upward by a smaller amount than the upper edge of the low beam light distribution pattern.

[0015] Conversely to the above configuration, if the lower edge of the additional light distribution pattern moves upward by a greater amount than the upper edge of the low beam light distribution pattern, the lower edge may separate upward from the upper edge. In this case, as described above, two peaks may be formed in the intensity distribution of the high beam light distribution pattern. However, in the above configuration, since the lower edge of the additional light distribution pattern moves upward by a smaller amount than the upper edge of the low beam light distribution pattern, the separation of the lower edge upward from the upper edge can be suppressed. Therefore, the formation of a valley between the two peaks can be suppressed, and the decrease in visibility can be suppressed.

[0016] Furthermore, when the control unit performs the temperature derating on the second light source, it may move the lower edge of the additional light distribution pattern upward after the upper edge of the low beam light distribution pattern has moved.

[0017] Conversely to the above configuration, if the lower edge of the additional light distribution pattern moves upward before it moves above the upper edge of the low beam light distribution pattern, the lower edge will move upward away from the upper edge, and as described above, two peaks may be formed in the intensity distribution of the high beam light distribution pattern. However, in the above configuration, since the lower edge of the additional light distribution pattern moves upward after the movement of the upper edge of the low beam light distribution pattern, the separation of the lower edge upward away from the upper edge can be suppressed. Therefore, the formation of a valley between the two peaks described above can be suppressed, and the decrease in visibility can be suppressed.

[0018] As described above, the present invention provides a vehicle headlight that can suppress the decrease in forward visibility when temperature derating is performed. [Brief explanation of the drawing]

[0019] [Figure 1] This is a schematic diagram showing a vehicle equipped with a vehicle headlight according to an embodiment of the present invention. [Figure 2] This is a schematic front view showing the second light source unit. [Figure 3] This is a diagram explaining duty cycle. [Figure 4]It is a diagram showing the relationship between the temperature T (°C) of the second light source unit and the duty ratio D (%) of each second light emitting unit. [Figure 5] It is a diagram showing an example of the duty ratio of the second light emitting unit after temperature dilation. [Figure 6] It is a diagram showing an example of the control flowchart of the control unit in the embodiment. [Figure 7] It is a diagram showing the state of change of the light distribution pattern of the low beam in step SP12. [Figure 8] It is a diagram showing the state of change of the additional light distribution pattern in step SP14. [Figure 9] It is a diagram showing a modified example of the first light emitting unit. [Figure 10] It is a diagram showing a modified example of the state of change of the light distribution pattern of the low beam in step SP12. [Figure 11] It is a diagram showing a modified example of the state of change of the additional light distribution pattern in step SP14.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, a preferred embodiment of a vehicle headlamp according to the present invention will be described in detail with reference to the drawings. The embodiments illustrated below are for facilitating the understanding of the present invention and are not for limiting the interpretation of the present invention. The present invention can be changed and improved without departing from its gist. Also, the present invention may appropriately combine the constituent elements in the embodiments illustrated below. In the drawings referred to below, for ease of understanding, the dimensions of each member may be shown changed.

[0021] FIG. 1 is a schematic view showing a vehicle equipped with a vehicle headlamp according to the present embodiment. As shown in FIG. 1, the vehicle headlamp 1 of the present embodiment includes a lamp unit 4 and a control unit CU. The vehicle headlamp 1 is for an automobile and is generally provided on each of the left and right sides in front of the vehicle VE. In this specification, "right" means the right side in the forward direction of the vehicle VE, and "left" means the left side in the forward direction of the vehicle VE. Each of the left and right vehicle headlamps 1 has the same configuration except that the shape is generally symmetric in the left-right direction. Therefore, hereinafter, one vehicle headlamp 1 will be described.

[0022] The lamp unit 4 is disposed in front of the vehicle VE and mainly includes a housing 10, a first light source unit 20, an actuator 30, a second light source unit 40, a temperature sensor 47, and an actuator 50.

[0023] The housing 10 mainly includes a housing 11 and an outer cover 12. The housing 11 is configured in a box shape having an opening in the front, and the outer cover 12 is fixed to the housing 11 so as to close the opening. Thus, an accommodation space surrounded by the housing 11 and the outer cover 12 is formed in the housing 10, and the first light source unit 20, the actuator 30, the second light source unit 40, the temperature sensor 47, and the actuator 50 are disposed in the accommodation space. The outer cover 12 transmits the light emitted from each of the first light source unit 20 and the second light source unit 40. The control unit CU is disposed outside the housing 10, but may be disposed in the accommodation space of the housing 10.

[0024] The first light source unit 20 emits first light forming a low-beam light distribution pattern in front of the vehicle VE. The first light source unit 20 mainly includes a first housing 21 having the same configuration as the housing 10, a first light emitting unit 23 disposed in the accommodation space of the first housing 21, and a first circuit board 25. In the accommodation space of the first housing 21, optical members such as reflectors and projection lenses, and shades may be disposed so that the first light forms a low-beam light distribution pattern.

[0025] An LED can be used as the first light-emitting unit 23. The first light-emitting unit 23 is mounted on the first circuit board 25. When power is supplied to the first light-emitting unit 23 from a power supply unit (not shown) via the first circuit board 25, it emits first light forward.

[0026] The actuator 30 is connected to the first housing 21 and is configured to change the vertical tilt of the first light source unit 20. The vertical tilt of the first light source unit 20 is changed by the actuator 30, for example, within a range of 0.01 degrees to 5 degrees. The vertical tilt of the light distribution patterns of the first light and the low beam is changed in accordance with the amount of change in the tilt of the first light source unit 20.

[0027] The second light source unit 40 emits second light that forms an additional light distribution pattern, which is added to the low beam light distribution pattern to form the high beam light distribution pattern. The second light source unit 40 mainly comprises a second housing 41 having the same configuration as the housing 10, and a plurality of second light-emitting units 43 and a second circuit board 45 arranged in the housing space of the second housing 41. Optical elements such as reflectors and projection lenses, as well as shades, may be arranged in the housing space of the second housing 41, similar to the first housing 21, so that the second light forms the additional light distribution pattern. The second light-emitting units 43 and the second circuit board 45 will be described later with reference to Figure 2.

[0028] The actuator 50 is connected to the second housing 41 and is configured to change the tilt of the second light source unit 40 in the vertical and horizontal directions. The vertical tilt of the second light source unit 40 is changed by the actuator 50, for example, in a range of 0.01 degrees to 5 degrees. The horizontal tilt of the second light source unit 40 is changed by the actuator 50, for example, in a range of 1 degree to 30 degrees. The vertical and horizontal tilts of the second light and the additional light distribution pattern are changed in accordance with the amount of change in the tilt of the second light source unit 40.

[0029] The control unit CU comprises a memory ME and a control unit CO.

[0030] Memory ME is configured to record information and to allow the recorded information to be read. Memory ME is, for example, a non-transitory recording medium, and semiconductor recording media such as RAM (Random Access Memory) or ROM (Read Only Memory) are preferred, but it can include any type of recording medium such as optical recording media or magnetic recording media. Note that "non-transitory" recording media includes all computer-readable recording media except transient propagation signals, and does not exclude volatile recording media. Memory ME may be provided inside the control unit CO.

[0031] The control unit CO consists of, for example, integrated circuits such as a microcontroller, IC (Integrated Circuit), LSI (Large-scale Integrated Circuit), and ASIC (Application Specific Integrated Circuit), as well as an NC (Numerical Control) device. Furthermore, if an NC device is used, the control unit CO may or may not use a machine learning machine. The control unit CO controls several components of the vehicle headlight 1.

[0032] The control unit CO is electrically connected to actuators 30 and 50, and by controlling them, adjusts the vertical tilt of the first light source unit 20 and the vertical and horizontal tilt of the second light source unit 40. By adjusting these tilts, the tilt of the first light emitted from the first light source unit 20, the second light emitted from the second light source unit 40, the low beam light distribution pattern, the additional light distribution pattern, and the high beam light distribution pattern are adjusted.

[0033] The control unit CO is electrically connected to the first light source unit 20 and the second light source unit 40 via a power supply unit (not shown) and controls them. In other words, the presence or absence of emission of the first and second light, and the intensity of each light, are adjusted by the control unit CO.

[0034] The control unit CO adjusts the power supplied to the first light-emitting unit 23 and the second light-emitting unit 43, for example, by PWM (Pulse Width Modulation) control. In this case, the control unit CO adjusts the power supplied to the first light-emitting unit 23 and the second light-emitting unit 43 by adjusting their duty cycles, and adjusts the amount of light emitted by adjusting the power. The larger the duty cycle, the greater the power applied to each. By adjusting the amount of light emitted, the light intensity distribution in the low beam light distribution pattern and the additional light distribution pattern are adjusted.

[0035] Figure 2 is a schematic front view showing the second light source unit 40. The second housing 41 is not shown in Figure 2. In Figure 2, each of the second light-emitting units 43 is shown as second light-emitting units 43a to 43h.

[0036] Examples of the second light-emitting units 43a to 43h include LEDs. The second light-emitting units 43a to 43h are arranged in an array in a single row in the left-right direction and mounted on the second circuit board 45. When power is supplied to each of the second light-emitting units 43a to 43h from a power supply unit (not shown) via the second circuit board 45, it emits second light forward.

[0037] The second light-emitting sections 43a to 43h generate heat when they emit second light. The heat from each of the second light-emitting sections 43a to 43h is transferred to the second circuit board 45. The greater the supplied power, the greater the amount of light emitted and the amount of heat generated by each of the second light-emitting sections 43a to 43h, and the higher the temperature of the second light source section 40. However, since the amount of heat generated by the second circuit board 45 is very small compared to the total amount of heat generated by the second light-emitting sections 43a to 43h, the temperature of the second light source section 40 can be considered to be based on the total amount of heat generated by the second light-emitting sections 43a to 43h.

[0038] The temperature sensor 47 is mounted on the second circuit board 45 and estimates the temperature of the second light source unit 40. For example, a thermistor can be used as such a temperature sensor 47. The temperature sensor 47 is electrically connected to the control unit CO and outputs a temperature signal related to the estimated temperature to the control unit CO. In this embodiment, the temperature sensor 47 is positioned away from each of the second light-emitting units 43a to 43h, and the temperature of the heat from the second light-emitting units 43a to 43h may decrease before it reaches the temperature sensor 47. Therefore, the control unit CO may estimate the temperature of the second light source unit 40 based on the temperature signal from the temperature sensor 47 and the distance between each of the second light-emitting units 43a to 43h and the temperature sensor 47.

[0039] The configuration and mounting position of the temperature sensor 47 are not particularly limited as long as the temperature sensor 47 can estimate the temperature of the second light source unit 40. For example, the temperature sensor 47 may be attached to each of the second light-emitting units 43a to 43h, placed in the housing space of the second housing 41, or mounted on another circuit board electrically connected to the second circuit board 45. As the temperature sensor 47, for example, a thermistor has been given, but a thermocouple may also be used. In addition, the control unit CO may estimate the temperature of the second light source unit 40 based on the power of each of the second light-emitting units 43a to 43h.

[0040] Next, we will explain the duty cycles 43aD to 43hD of each of the second light-emitting sections 43a to 43h when the vehicle VE is moving straight. Figure 3 is a diagram illustrating the duty cycles 43aD to 43hD, and in Figure 3, the values ​​of the duty cycles 43aD to 43hD are represented by the height of the rectangle shown in Figure 3.

[0041] The control unit CO sets the duty cycles 43dD and 43eD of the second light-emitting units 43d and 43e, which are located in the center of the left-right direction among the second light-emitting units 43a to 43h, to the highest values. Furthermore, the control unit CO gradually decreases the duty cycles from the left of the second light-emitting unit 43d to the right of the second light-emitting unit 43e. In this embodiment, the control unit CO sets the duty cycles 43dD to 43a for the second light-emitting units 43d to 43a to 100%, 80%, 60%, and 40%, respectively. Similarly, the control unit 70 sets the duty cycles 43eD to 43h for the second light-emitting units 43e to 43h to 100%, 80%, 60%, and 40%, respectively. The values ​​of the duty cycles 43aD to 43hD are recorded as information in the memory ME, and the control unit CO reads these values ​​from the memory ME and controls the duty cycles 43aD to 43hD as described above. The above values ​​for the duty cycle are not particularly limited.

[0042] When the control unit CO controls the duty cycle 43aD to 43hD as described above, the second light-emitting units 43d and 43e, located towards the center in the left-right direction, emit the most light. Conversely, the second light-emitting units located further away from 43d and 43e towards the left and right ends emit less light. Since the light emission is the same for the second light-emitting units 43a to 43h if the duty cycle is the same, the light emission is symmetrical between the left and right second light-emitting units. As a result, the hot zone, which is the region with the highest intensity of the second light in the additional light distribution pattern, is located approximately in the center of the additional light distribution pattern in the left-right direction.

[0043] Each of the second light-emitting units 43a to 43h generates heat when emitting second light at the duty cycle described above. The temperature of the second light source unit 40 due to the heat generated by the second light-emitting units 43a to 43h is estimated by the temperature sensor 47 as described above, and the temperature sensor 47 outputs a temperature signal to the control unit CO. Based on the temperature signal, the control unit CO performs temperature derating on each of the second light-emitting units 43a to 43h of the second light source unit 40.

[0044] Next, temperature derating in the second light source unit 40 will be explained. Figure 4 is a diagram showing the relationship between the temperature T (°C) of the second light source unit 40 estimated by the temperature sensor 47 and the duty cycle D (%) of the second light-emitting unit 43. The horizontal axis of Figure 4 represents temperature T, and the vertical axis of Figure 4 represents duty cycle D. In Figure 4, temperatures T1, T2, and T3 are, for example, 80°C, 90°C, and 120°C. Temperature T1 is the temperature at which the control unit CO starts temperature derating. If temperature T is lower than temperature T1, temperature derating is not performed, and if temperature T is equal to or greater than temperature T1, temperature derating is performed. The duty cycle D1 corresponding to temperatures lower than temperature T1 is set to 100%, and the duty cycles D2 and D3 corresponding to temperatures T2 and T3 are, for example, 70% and 30%. The duty cycle corresponding to temperature T1 is set lower than duty cycle D1 and higher than duty cycle D2. At duty cycle D3, the reduction in duty cycle is maximized when temperature derating is performed. The relationship between temperature T and duty cycle D, the values ​​of temperatures T1, T2, and T3, and the values ​​of duty cycles D2 and D3 are recorded as information in memory ME. Note that these values ​​are not particularly limited.

[0045] In temperature derating, the control unit CO controls the duty cycle of the second light-emitting unit 43 based on the duty cycle corresponding to temperature T when the temperature T is T1 or higher. For example, when the temperature T is T2, the control unit CO controls the duty cycle of the second light-emitting unit 43 based on the duty cycle D2. In the temperature derating of this embodiment, when the temperature T is T1 or higher, the control unit CO lowers the duty cycle of the second light-emitting unit 43 if it is greater than the duty cycle corresponding to temperature T. It also maintains the duty cycle of the second light-emitting unit 43 that is driven at a duty cycle less than or equal to the duty cycle corresponding to temperature T. This control of the duty cycle will be explained below using temperature T2 as the temperature at which temperature derating is performed, and temperature T2 and the duty cycle D2 corresponding to temperature T2.

[0046] Figure 5 shows an example of the duty cycles 43aD to 43hD of the second light-emitting sections 43a to 43h after temperature derating while the vehicle VE is moving in a straight line. In Figure 5, as in Figure 3, the duty cycles 43aD to 43hD are represented by the height of the rectangle shown in Figure 5. In addition, to compare the respective duty cycles 43aD to 43hD in Figure 3 and Figure 5, the portion of the duty cycle that has decreased from the state shown in Figure 3 is indicated by a dashed line in Figure 5.

[0047] When the temperature T is T2, the control unit CO lowers the duty cycles 43cD to 43fD of the second light-emitting units 43a to 43f that have a duty cycle greater than D2 to duty cycle D2, controlling them to 70%. The control unit CO also maintains the duty cycles 43aD, 43bD, 43gD, and 43hD of the second light-emitting units 43a, 43b, 43g, and 43h that have a duty cycle of D2 or less, as shown in Figure 3. As the duty cycles 43cD to 43fD decrease, the amount of heat generated by the second light source unit 40 decreases, and the temperature of the second light source unit 40 drops.

[0048] Next, the operation of the vehicle headlight 1 will be explained.

[0049] Figure 6 shows an example of a control flowchart for the control unit CO in the embodiment. As shown in Figure 6, the control flow of this embodiment includes steps SP11 to SP14. However, the control flow is not limited to this. In the initial state shown in Figure 6, the vehicle VE is moving straight, emitting first and second light, and the high beam light distribution pattern is formed by the first and second light. The duty cycles 43aD to 43hD of the second light-emitting unit 43 that emits the second light are as shown in Figure 3. Also, in the initial state, the temperature sensor 47 estimates the temperature of the second light source unit 40, and the temperature signal is input to the control unit CO.

[0050] (Step SP11) In this step, the control unit CO repeats step SP11 if the temperature T indicated by the temperature signal from the temperature sensor 47 is less than temperature T1. If temperature T is equal to or greater than temperature T1, the control unit CO proceeds to step SP12.

[0051] (Step SP12) In this step, before temperature derating, the control unit CO controls the actuator 30 to tilt the first light source unit 20 upward, moving at least the upper edge of the low beam light distribution pattern upward. In this embodiment, since the entire first light source unit 20 is tilted, the control unit CO moves the lower and upper edges of the low beam light distribution pattern upward by the same amount. Figure 7 shows the change in the low beam light distribution pattern 101 of the high beam light distribution pattern 105. In Figure 7, the low beam light distribution pattern 101 before movement is shown by a dashed line, and the low beam light distribution pattern 101 after movement is shown by a solid line. In this step, the additional light distribution pattern 103 does not move. The light distribution patterns 101, 103, and 105 shown in Figure 7 refer to both the shape of the image formed on a virtual vertical screen, for example, 25 m in front of the vehicle VE, and the light intensity distribution in that image. As the low beam light distribution pattern 101 moves upward, the upper edge of the low beam light distribution pattern 101 overlaps further with the lower edge of the additional light distribution pattern 103 by the amount that the upper edge of the low beam light distribution pattern 101 has moved upward, thus illuminating the lower edge of the additional light distribution pattern 103.

[0052] In this step, when the control unit CO performs temperature derating on the second light source unit 40, it may increase the amount of movement of the upper edge of the low beam light distribution pattern 101 according to the vehicle VE's travel speed. In this case, for example, information related to speed is input to the control unit CO from an ECU (Electronic Control Unit) (not shown) of the vehicle VE, and the control unit CO uses this information. With the above configuration, when the vehicle VE is traveling at a high speed, the amount of movement of the upper edge is greater than when the vehicle VE is traveling at a low speed, allowing the driver to see far ahead in a bright condition, and potentially improving safety. However, when the control unit CO performs temperature derating on the second light source unit 40, it is not necessary to increase the amount of movement of the upper edge of the low beam light distribution pattern 101 according to the vehicle VE's travel speed.

[0053] Furthermore, in this step, if the control unit CO performs temperature derating on the second light source unit 40, it may increase the movement speed of the upper edge of the low beam light distribution pattern 101 according to the vehicle VE's travel speed. With the above configuration, when the vehicle VE is traveling fast, the movement speed of the upper edge becomes faster than when the vehicle VE is traveling slow, allowing the driver to see far ahead quickly and in a bright state, potentially improving safety. However, if the control unit CO performs temperature derating on the second light source unit 40, it is not necessary to increase the movement speed of the upper edge of the low beam light distribution pattern 101 according to the vehicle VE's travel speed.

[0054] When the control unit CO moves the low beam light distribution pattern 101 upwards, it advances the control flow to step SP13.

[0055] (Step SP13) In this step, the control unit CO performs temperature derating on the second light source unit 40. During temperature derating, if the temperature T is equal to temperature T2, the control unit CO controls the duty cycle 43aD to 43hD as explained above using Figure 5. As a result, the amount of heat generated by the second light source unit 40 decreases, and the temperature of the second light source unit 40 drops. The control unit CO performs temperature derating, for example, 1 second after the upper edge of the low beam light distribution pattern 101 has finished moving in step SP12, but it may also perform temperature derating simultaneously with the completion of the movement, and the timing of temperature derating is not particularly limited.

[0056] Incidentally, the additional light distribution pattern 103 tends to be darker at the upper and lower edges than at the center. When the control unit CO performs temperature derating as described above, the amount of light emitted from the second light source unit 40 decreases, the center of the additional light distribution pattern 103 becomes darker, and the upper and lower edges of the additional light distribution pattern 103 become even darker. With respect to the darkened additional light distribution pattern 103, as explained in step SP12, the upper edge of the low beam light distribution pattern 101 moves upward. Therefore, the decrease in brightness due to temperature derating is suppressed at the lower edge of the additional light distribution pattern 103.

[0057] When the control unit CO performs temperature derating on the second light source unit 40, it proceeds to step SP14 of the control flow.

[0058] (Step SP14) In this step, the control unit CO controls the actuator 50 to tilt the second light source unit 40 upward, moving at least the upper edge of the additional light distribution pattern 103 upward. In this embodiment, since the entire second light source unit 40 is tilted, the control unit CO moves the lower and upper edges of the additional light distribution pattern 103 upward by the same amount. The control unit CO moves at least the upper edge of the additional light distribution pattern 103, for example, 1 second after the completion of temperature derating, but it may also move it simultaneously with the completion of the movement, and the timing of the movement is not particularly limited. Figure 8 shows the changes in the additional light distribution pattern 103 within the high beam light distribution pattern 105. In Figure 8, the additional light distribution pattern 103 before movement shown in Figure 7 is shown with a dashed line, and the additional light distribution pattern 103 before movement is shown with a solid line. In this step, the control unit CO moves the additional light distribution pattern 103 when the additional light distribution pattern 103 visually overlaps with the low beam light distribution pattern 101. Furthermore, the control unit CO moves the additional light distribution pattern 103 upward with a smaller amount of movement than the low beam light distribution pattern 101. This suppresses the formation of a gap between the additional light distribution pattern 103 and the low beam light distribution pattern 101 that would visually appear to the human eye as not overlapping with the first light and the second light. When the control unit CO performs temperature derating in step SP13, as described above, the central side of the additional light distribution pattern 103 becomes darker, and the upper edge side becomes even darker. When the upper edge side becomes even darker, the driver is likely to visually perceive the upper edge of the additional light distribution pattern 103 as lowering, and the additional light distribution pattern 103 as narrowing vertically. However, when the upper edge of the additional light distribution pattern 103 moves upward, the area in the driver's line of sight becomes brighter when the driver is viewing distant objects, and the driver's perception of the upper edge lowering is suppressed.

[0059] In this step, if the control unit CO performs temperature derating on the second light source unit 40, it may increase the amount of movement of the upper edge of the additional light distribution pattern 103 according to the travel speed of the vehicle VE. With the above configuration, when the vehicle VE is traveling at a high speed, the amount of movement of the upper edge will be greater than when the vehicle VE is traveling at a low speed, allowing the driver to see further ahead and potentially improving safety. However, if the control unit CO performs temperature derating on the second light source unit 40, it is not necessary to increase the amount of movement of the upper edge of the additional light distribution pattern 103 according to the travel speed of the vehicle VE.

[0060] Furthermore, in this step, if the control unit CO performs temperature derating on the second light source unit 40, it may increase the movement speed of the upper edge of the additional light distribution pattern 103 according to the travel speed of the vehicle VE. With the above configuration, when the vehicle VE is traveling at a high speed, the movement speed of the upper edge will be faster than when the vehicle VE is traveling at a low speed, allowing the driver to see further ahead and earlier, potentially improving safety. However, if the control unit CO performs temperature derating on the second light source unit 40, it is not necessary to increase the movement speed of the upper edge of the additional light distribution pattern 103 according to the travel speed of the vehicle VE.

[0061] The control unit CO terminates the control flow when it moves the additional light distribution pattern 103 upward.

[0062] As described above, when the control unit CO of this embodiment performs temperature derating on the second light source unit 40 based on the temperature signal from the temperature sensor 47 while the high beam light distribution pattern 105 is being formed, it moves at least the upper edge of the low beam light distribution pattern 101 upward, as described in step SP12.

[0063] According to the above configuration, the upward movement of the upper edge of the low beam light distribution pattern 101 allows the upper edge side of the low beam light distribution pattern 101 to brighten the lower edge side of the additional light distribution pattern 103, which becomes darker due to temperature derating. Therefore, a decrease in visibility can be suppressed.

[0064] Furthermore, when the control unit CO performs temperature derating on the second light source unit 40, it moves the upper edge of the low beam light distribution pattern 101 upward before performing temperature derating, as described in steps SP12 and SP13.

[0065] Conversely to the above configuration, if the upper edge of the low beam light distribution pattern 101 moves upward after temperature derating, two peaks may be formed in the intensity distribution of the high beam light distribution pattern 105 between the time after temperature derating and the time the upper edge of the low beam light distribution pattern moves, due to the region with the highest intensity in the low beam light distribution pattern 101 and the region with the highest intensity in the additional light distribution pattern 103. When two peaks are formed, the region corresponding to the intensity dip located between the two peaks in the high beam light distribution pattern 105 tends to be darker than the regions on either side of the dip. If the region corresponding to the dip is located in the driver's line of sight, the driver may perceive that the area in their line of sight is darker than elsewhere, potentially reducing visibility. However, in the above configuration, since the upper edge of the low beam light distribution pattern 101 moves upward before temperature derating, the formation of a dip between the two peaks can be suppressed. Therefore, the reduction in visibility can be suppressed compared to the case where a dip is formed.

[0066] In steps SP12 and SP13, the control unit CO may perform temperature derating between the start and end of upward movement of the upper edge of the low beam light distribution pattern 101. Alternatively, the control unit CO may perform steps SP12 and SP13 simultaneously, starting the movement of the upper edge of the low beam light distribution pattern 101 and temperature derating at the same time, or ending the movement of the upper edge and temperature derating at the same time. Or, the control unit CO may proceed with the control flow in the order of steps SP13, SP12, and SP14, moving the upper edge of the low beam light distribution pattern 101 after temperature derating. In this case, the control unit CO may move the upper edge of the low beam light distribution pattern 101 for example 1 second after the end of temperature derating, or simultaneously with the end of the end. Alternatively, the control unit CO may start and end the movement of the upper edge of the low beam light distribution pattern 101 during temperature derating. Furthermore, the control unit CO may combine the above for the timing of the start of movement of the upper end, the end of movement of the upper end, the start of temperature derating, and the end of temperature derating.

[0067] Furthermore, when the control unit CO performs temperature derating on the second light source unit 40, it moves at least the upper edge of the additional light distribution pattern 103 upward, as described in step SP14.

[0068] When the control unit CO performs temperature derating on the second light source unit 40, the central side of the additional light distribution pattern 103 becomes darker than before temperature derating, and the upper edge side becomes even darker. When the upper edge side becomes even darker, the driver is more likely to feel a sense of unease as if the upper edge has lowered. In the above configuration, when the control unit CO performs temperature derating on the second light source unit 40, it moves at least the upper edge of the additional light distribution pattern 103 upward. When the upper edge of the additional light distribution pattern 103 moves upward, the area in the driver's line of sight becomes brighter when the driver is viewing distant objects, which can suppress the driver from feeling a sense of unease as if the upper edge has lowered, and thus can suppress a decrease in visibility. Note that the control unit CO does not necessarily have to move the upper edge of the additional light distribution pattern 103 upward.

[0069] Furthermore, in step SP14, when the control unit CO performs temperature derating on the second light source unit 40, it raises the lower edge of the additional light distribution pattern 103. In this case, the control unit CO moves the lower edge of the additional light distribution pattern 103 upward by a smaller amount than the upper edge of the low beam light distribution pattern 101.

[0070] Conversely to the above configuration, if the lower edge of the additional light distribution pattern 103 moves upward by a greater amount than the upper edge of the low beam light distribution pattern 101, the lower edge may move upward away from the upper edge. In this case, as described above, two peaks may be formed in the intensity distribution of the high beam light distribution pattern 105. However, in the above configuration, since the lower edge of the additional light distribution pattern 103 moves upward by a smaller amount than the upper edge of the low beam light distribution pattern 101, the separation of the lower edge upward away from the upper edge can be suppressed. Therefore, the formation of a valley between the two peaks can be suppressed, and the decrease in visibility can be suppressed compared to the case where a valley is formed. The control unit CO may also move the lower edge of the additional light distribution pattern 103 upward by the same amount as the upper edge of the low beam light distribution pattern 101.

[0071] Furthermore, when the control unit CO performs temperature derating on the second light source unit 40, it moves the lower edge of the additional light distribution pattern 103 upward after the upper edge of the low beam light distribution pattern 101 has moved, as described in steps SP12 and SP14.

[0072] Conversely to the above configuration, if the lower edge of the additional light distribution pattern 103 moves upward before the upper edge of the low beam light distribution pattern 101 moves upward, the lower edge will move upward away from the upper edge, and as described above, two peaks may be formed in the intensity distribution of the high beam light distribution pattern 105. However, in the above configuration, since the lower edge of the additional light distribution pattern 103 moves upward after the upper edge of the low beam light distribution pattern 101 moves upward, the separation of the lower edge upward away from the upper edge can be suppressed. Therefore, the formation of a valley between the two peaks described above can be suppressed, and the decrease in visibility can be suppressed.

[0073] The control unit CO may start and end the movement of the lower edge of the additional light distribution pattern 103 between the start and end of the upward movement of the upper edge of the low beam light distribution pattern 101, or it may start the movement of the lower end for, for example, 10 seconds after the end of the movement of the upper edge. The control unit CO may also start and end the movement of the lower edge of the additional light distribution pattern 103 at the same time as the start and end of the movement of the upper edge of the low beam light distribution pattern 101. Furthermore, the control unit CO may move the lower edge of the additional light distribution pattern 103 upward before the upper edge of the low beam light distribution pattern 101, or it may move it at the same time as the upper end. In this case, the control unit CO may start the upward movement of the upper edge of the low beam light distribution pattern 101 at the same time as the end of the movement of the lower edge of the additional light distribution pattern 103, or it may start the upward movement of the upper edge of the low beam light distribution pattern 101 for, for example, 10 seconds after the end of the movement of the lower edge of the additional light distribution pattern 103. Alternatively, the control unit CO may start and end the upward movement of the upper edge of the low beam light distribution pattern 101 between the start and end of the movement of the lower edge of the additional light distribution pattern 103. The control unit CO may also combine the above timings for the start and end of the movement of the upper end of the low beam light distribution pattern 101, the start of the movement of the lower end of the additional light distribution pattern 103, and the end of the movement of the upper end.

[0074] Furthermore, the control unit CO may start and stop the upward movement of the lower edge of the additional light distribution pattern 103 during temperature derating. Alternatively, the control unit CO may start and stop the movement of the lower edge of the additional light distribution pattern 103 before the start of temperature derating, or it may perform temperature derating between the start and end of the movement of the lower edge of the additional light distribution pattern 103. Alternatively, the control unit CO may perform temperature derating, for example, 1 second after the end of the movement of the lower end. The control unit CO may combine the above timings for the start of the movement of the lower end, the end of the movement of the lower end, the start of temperature derating, and the end of temperature derating.

[0075] Furthermore, when the control unit CO performs temperature derating on the second light source unit 40, it may simultaneously perform step SP12, which moves the upper edge of the low beam light distribution pattern 101 upward, and step SP14, which moves the lower edge of the additional light distribution pattern 103 upward. In this case, the control unit CO may set the movement speed of the lower edge of the additional light distribution pattern 103 to be less than or equal to the movement speed of the upper edge of the low beam light distribution pattern 101.

[0076] In the above configuration, the lower edge of the additional light distribution pattern 103 moves upward simultaneously with the upper edge of the low beam light distribution pattern 101. However, if the movement speed of the lower edge is faster than that of the upper edge, the lower edge will move upward away from the upper edge, and as described above, two peaks may be formed in the intensity distribution of the high beam light distribution pattern 105. However, in the above configuration, the lower edge of the additional light distribution pattern 103 moves upward simultaneously with the upper edge of the low beam light distribution pattern 101, and the movement speed of the lower edge is less than or equal to that of the upper edge. This can suppress the lower edge from moving upward away from the upper edge. Therefore, the formation of a valley between the two peaks described above can be suppressed, and the decrease in visibility can be suppressed. Note that the control unit CO does not need to make the movement speed of the lower edge of the additional light distribution pattern 103 less than or equal to the movement speed of the upper edge of the low beam light distribution pattern 101.

[0077] In this embodiment, the first light-emitting unit 23 was described as a single LED and the second light-emitting unit 43 as an LED array, but the configurations of the first light-emitting unit 23 and the second light-emitting unit 43 are not limited to these. A micro-LED is an example of a modified version of the first light-emitting unit 23 and the second light-emitting unit 43. In this case, since the first light-emitting unit 23 and the second light-emitting unit 43 have generally the same configuration, the first light-emitting unit 23 will be used as the basis for this explanation.

[0078] Figure 9 shows a modified example of the first light-emitting unit 23. The first light-emitting units 23 are arranged in a matrix and are aligned in the vertical and horizontal directions. There are 256 first light-emitting units 23 in the horizontal direction and 64 in the vertical direction, but the number is not particularly limited. These first light-emitting units 23 are preferably so-called micro-LED arrays. The first light-emitting units 23 can individually change the presence or absence of first light emission and the amount of light emitted by the control unit CO.

[0079] The control unit CO can form a predetermined low-beam light distribution pattern 101 by selecting the first light-emitting unit 23 that emits light. Furthermore, the control unit CO can adjust the light intensity distribution in the low-beam light distribution pattern 101 by adjusting the amount of light emitted from each of the first light-emitting units 23.

[0080] If the first light-emitting units 23 are arranged in a matrix, the control unit CO may, in step SP12, move the upper edge of the low-beam light distribution pattern 101 upward and maintain the lower edge, as shown by the solid line in Figure 10. In this case, the control unit CO controls the first light-emitting units 23 to maintain the light emission of some of the first light-emitting units 23, and emits first light from some of the other first light-emitting units 23 that need to emit light to achieve the light distribution pattern shown by the solid line in Figure 10, thereby instantaneously moving the upper edge of the low-beam light distribution pattern 101 upward. With such control, the lower edge side of the additional light distribution pattern 103, which becomes darker due to temperature derating, can be instantly brightened, and the actuator 30 may become unnecessary.

[0081] Furthermore, if all of the other first light-emitting units 23 that require illumination are rapidly illuminated, the low beam light distribution pattern 101 shown by the dotted line in Figure 10 will instantly change to the low beam light distribution pattern 101 shown by the solid line. Also, if the first light-emitting units 23 that require illumination are sequentially emitted from the first light-emitting units 23 closest to the first light-emitting units 23 that are already emitting light in order to form the low beam light distribution pattern 101 shown by the dotted line in Figure 10, the low beam light distribution pattern 101 will gradually change to the low beam light distribution pattern 101 shown by the solid line.

[0082] If the second light-emitting units 43 are arranged in a matrix, the control unit CO may, in step SP14, move the upper edge of the additional light distribution pattern 103 upward and maintain the lower edge, as shown in Figure 11. In this case, the control unit CO controls the second light-emitting units 43 to maintain the emission of light from some of the second light-emitting units 43, and emits second light from the other second light-emitting units 43 that are necessary to emit light to achieve the light distribution pattern shown by the solid line in Figure 11, thereby instantaneously moving the upper edge of the additional light distribution pattern 103 upward. With this type of control, the actuator 50 becomes unnecessary, and the second light can be instantaneously irradiated at a distance.

[0083] Even if the first light-emitting section 23 and the second light-emitting section 43 are arranged in a matrix, the first and second lights emitted from the luminaire unit 4 may be tilted upward using actuators 30 and 50, as in the embodiment.

[0084] Although the present invention has been described above with reference to the above embodiments, the present invention is not limited to these.

[0085] The control unit CO may, in step SP12, move at least the upper edge of the low beam light distribution pattern 101 upward as the temperature T of the second light source unit 40 increases. The higher the temperature T, the darker the additional light distribution pattern 103 becomes due to temperature derating. In the above configuration, as the additional light distribution pattern 103 becomes darker, the upper edge of the low beam light distribution pattern 101 moves upward, so the upper edge side of the low beam light distribution pattern 101 can brighten the lower edge side of the additional light distribution pattern 103, which becomes darker due to temperature derating. Therefore, a decrease in visibility can be suppressed. Also, the control unit CO may, in step SP14, move at least the upper edge of the additional light distribution pattern 103 upward as the temperature T increases. As described above, the higher the temperature T, the darker the center side of the additional light distribution pattern 103 becomes, and the upper edge side becomes even darker. If the upper edge becomes even darker, the driver is likely to visually perceive the upper edge of the additional light distribution pattern 103 as lowering, and feel a sense of unease as if the additional light distribution pattern 103 has narrowed vertically. In the above configuration, since the upper edge of the additional light distribution pattern 103 moves upward, the area in the driver's line of sight becomes brighter when the driver is looking into the distance, and the driver's sense of unease as if the upper edge has lowered is suppressed.

[0086] In the control flow, step SP14 may be omitted. Also, the order of steps SP12, SP13, and SP14 is not particularly limited, and several steps may be performed simultaneously. Furthermore, the amount of upward movement of the upper edge of the low beam light distribution pattern 101 may be the same as, or less than, the amount of upward movement of the upper edge of the additional light distribution pattern 103. Furthermore, the amount of upward movement of the low beam light distribution pattern 101 may be the same as, or more than, the amount of upward movement of the additional light distribution pattern 103. In addition, in step SP12, the control unit CO may move at least the upper edge of the low beam light distribution pattern 101 upward gradually, stepwise, or instantaneously. The control unit CO may move at least the upper edge of the additional light distribution pattern 103 upward gradually, stepwise, or instantaneously.

[0087] The control unit CO performs temperature derating based on the duty cycle 43aD to 43lh, but it may also perform temperature derating based on the current flowing through the second light-emitting units 43a to 43h. Therefore, the control unit 70 can perform temperature derating based on the power supplied to the second light-emitting units 43a to 43h.

[0088] The first housing 21 and the second housing 41 do not necessarily have outer covers 12. The configuration of the first light source unit 20, including the first light-emitting unit 23, is not particularly limited as long as the first light can form a low-beam light distribution pattern. Also, the configuration of the second light source unit 40, including the second light-emitting unit 43, is not particularly limited as long as the second light can form an additional light distribution pattern.

[0089] According to the present invention, a vehicle headlight is provided that can suppress the decrease in forward visibility when temperature derating is performed, and can be used in fields such as automobiles.

Claims

1. A first light source unit emits a first light that forms the low beam light distribution pattern in front of the vehicle, A second light source unit emits second light that forms an additional light distribution pattern, which is added to the low beam light distribution pattern to form a high beam light distribution pattern, Control unit and Equipped with, When the control unit performs temperature derating on the second light source based on the temperature of the second light source while the high beam light distribution pattern is being formed, it moves at least the upper edge of the low beam light distribution pattern upward. A vehicle headlight characterized by the following features.

2. When the control unit performs the temperature derating on the second light source, it moves the upper edge of the low beam's light distribution pattern upward before performing the temperature derating. The vehicle headlight according to feature 1.

3. When the control unit performs the temperature derating on the second light source, it increases the amount of movement of the upper edge of the low beam's light distribution pattern according to the vehicle's travel speed. A vehicle headlight according to claim 1 or 2.

4. When the control unit performs the temperature derating on the second light source, it moves at least the upper edge of the additional light distribution pattern upward. A vehicle headlight according to claim 1 or 2.

5. When the control unit performs the temperature derating on the second light source, it moves the lower edge of the additional light distribution pattern upward by a smaller amount than the upper edge of the low beam light distribution pattern. A vehicle headlight according to claim 1 or 2.

6. When the control unit performs the temperature derating on the second light source, it moves the lower edge of the additional light distribution pattern upward after the upper edge of the low beam light distribution pattern has moved. A vehicle headlight according to claim 1 or 2.

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