Vehicle headlight system

Abstract

Vehicle headlight system (100), comprising: a headlight unit (20) that combines light beams from a plurality of light-emitting elements (28) to illuminate with a predetermined beam; a control unit (26) that controls a change in the luminance of the plurality of light-emitting elements (28) in accordance with an instruction from a vehicle and / or information indicating a driving condition; and a storage unit (34) that stores information indicating a priority of an event that causes the luminance of the plurality of light-emitting elements (28) to be changed, wherein, in a case where a second event occurs while the luminance of the plurality of light-emitting elements (28) is gradually changed to reach a first luminance in a first duration corresponding to a first event, the control unit gradually changes: (i) the luminance of the plurality of light-emitting elements (28) to reach a second luminance in a second duration corresponding to the second event if the priority of the second event is higher than the priority of the first event; and (ii) the luminance of the plurality of light-emitting elements (28) to reach the second luminance regardless of the second duration if the priority of the second event is lower than the priority of the first event.

Description

[0001] The present invention relates to vehicle headlight systems.

[0002] Typically, a vehicle headlight can switch between a low beam and a high beam. The low beam illuminates a nearby area with a predetermined illuminance. The light distribution patterns of the low beam are controlled so as not to dazzle oncoming vehicles or vehicles ahead, and the low beam is primarily used when the vehicle is traveling in an urban area. Meanwhile, the high beam illuminates a distant, wide area ahead with a relatively high illuminance and is primarily used when the vehicle is traveling at high speed on a road with few oncoming vehicles or vehicles ahead.Accordingly, the high beam provides better visibility for the driver than the low beam, but disadvantageously it causes glare for a driver of a preceding vehicle or an oncoming vehicle or for a pedestrian.

[0003] In recent years, a technique for dynamically and adaptively controlling a high beam distribution pattern based on a vehicle's environmental conditions has been proposed (see, for example, JP 2008-137516 A). According to this technique, the presence of a preceding vehicle, an oncoming vehicle, or a pedestrian is detected, and light in an area corresponding to the detected vehicle or pedestrian is attenuated to reduce glare to the vehicle or pedestrian.

[0004] In a vehicle headlight system such as that described in JP 2008-137516 A, when a predetermined light distribution pattern in the middle of a change associated with a certain event is to be changed to a different light distribution pattern associated with another event that occurred after the aforementioned event, the light distribution pattern is changed with the priority assigned to a change time corresponding to the later-occurring event. This may be preferable in terms of simplifying control, but it leaves room for improvement in terms of driver comfort.

[0005] The present invention has been made in view of such a situation and aims to provide a vehicle headlight system that can improve the comfort of a driver.

[0006] To solve the problem described above, a vehicle headlight system according to one aspect of the present invention includes a headlight unit that combines light beams from a plurality of light-emitting elements to illuminate with a predetermined beam, a control unit that controls a change in the luminance of the plurality of light-emitting elements in accordance with an instruction from a vehicle and / or information indicative of a driving condition, and a storage unit that stores information indicating a priority of an event that causes the luminance of the plurality of light-emitting elements to be changed.In a case where a second event occurs while the luminance of the plurality of light-emitting elements is gradually changed to reach the first luminance in a first duration corresponding to a first event, the control unit gradually changes: (i) the luminance of the plurality of light-emitting elements to reach the second luminance in a second duration corresponding to the second event if the priority of the second event is higher than the priority of the first event; and (ii) the luminance of the plurality of light-emitting elements to reach the second luminance regardless of the second duration if the priority of the second event is lower than the priority of the first event.

[0007] Embodiments will now be described by way of example only with reference to the accompanying drawings, which are given as non-limiting examples and in which like elements are numbered alike in several figures, and in which: is Fig. 1 is a block diagram of a vehicle headlight system according to an embodiment; illustrated Fig. 2 an example of a data structure of a storage unit; illustrated Fig. 3 schematically shows a light distribution pattern formed by a vehicle headlight; illustrate Fig. 4A to 4E show an example of a luminance distribution of each sub-area of ​​a high beam distribution pattern; and illustrated Fig. Figure 5 shows an example of a change in the luminance of an LED and illustrates another example of the distribution.

[0008] The invention will now be described by reference to the preferred embodiments. This is not intended to limit the scope of the present invention, but rather to illustrate the invention by way of example. The size of the components in each figure may be changed to aid understanding. Some of the components in each figure may be omitted if they are not important to the explanation.

[0009] Fig. 1 is a block diagram of a vehicle headlight system 100 according to one embodiment. The vehicle headlight system 100 includes a vehicle speed sensor 10, a steering angle sensor 12, a camera 14, a vehicle control unit 16, and a vehicle headlight 18.

[0010] The vehicle speed sensor 10 detects the rotational speed of the wheels to determine the vehicle's speed. The steering angle sensor 12 detects the steering angle of the steering wheel. The camera 14 captures an image of an area in front of the vehicle.

[0011] The vehicle control unit 16 controls the vehicle as a whole. The vehicle control unit 16 detects the presence of a preceding vehicle or an oncoming vehicle and the position of the detected vehicle based on the image information obtained from the camera 14. Based on this detection result, the vehicle speed information, and the steering angle information, the vehicle control unit 16 determines a light distribution pattern formed by a combination of an on area to be illuminated with a light beam and an off area (blocked area) that is not to be illuminated with a light beam. The vehicle control unit 16 transmits a pattern instruction S1 indicating the determined light distribution pattern to the vehicle headlight 18.

[0012] The vehicle headlight 18 forms a high beam distribution pattern. The actual vehicle headlight 18 is equipped with, in addition to a high beam, an additional high beam for illuminating a more distant area, a low beam, a clearance lamp, and so on, but these are omitted here.

[0013] The vehicle headlight 18 includes a headlight unit 20, a semiconductor switch 22, a lighting circuit 24, and a headlight control unit 26. The actual vehicle headlight system 100 is provided by a pair of right and left vehicle headlights 18, but only one of the two is shown herein.

[0014] The headlight unit 20 includes several light-emitting semiconductor elements (e.g., LEDs) 28 that can be individually switched on / off. Each LED 28 is illuminated when a control current I LD turned on.

[0015] The semiconductor switch 22 is provided on a path through which power is supplied from a battery (not illustrated) to the lighting circuit 24, and the on / off of the semiconductor switch 22 is controlled in accordance with a control signal S2 from the headlight control unit 26. The semiconductor switch 22 is turned on when the LEDs 28 are turned on.

[0016] A storage unit 34 stores information pertinent to an event that causes a light distribution pattern to change (i.e., that causes the luminance of an LED 28 to change). Fig. 2 illustrates an example of a data structure of the storage unit 34. The storage unit 34 stores an event 34a, a priority 34b, and a time 34c of a step change, which are linked to each other.

[0017] Event 34a indicates an event that causes the luminance of an LED 28 to change. The term "light change" means switching a high beam on / off, or more precisely, switching on / off by the driver or automatic switching on / off by an automatic high beam control. The term "target detection" means detection of a preceding vehicle or an oncoming vehicle. In this case, an LED 28 illuminating the preceding vehicle or the oncoming vehicle is switched off.

[0018] The term "vehicle speed change" means a change in vehicle speed, or more specifically, a change in vehicle speed between a high speed (e.g., over 80 km / h), a medium speed (e.g., from 60 km / h to 80 km / h), and a low speed (e.g., less than 60 km / h). In this case, a change is made to a high-speed mode suitable for high-speed driving, a medium-speed mode suitable for medium-speed driving, or a low-speed mode suitable for low-speed driving, and the light distribution pattern is changed accordingly. The term "steering angle change" means a change in the steering angle, or more specifically, means that the steering angle has reached, exceeded, or fallen below a predetermined value (e.g., 10°).In this case, the light distribution pattern is changed so that the direction of travel is illuminated.

[0019] The priority 34b indicates which step change time should be given higher priority when a light distribution pattern that is in the middle of a change in association with a specific event is to be changed to a different light distribution pattern in association with another event that occurred after the aforementioned event. In this example, a smaller number indicates a higher priority. The step change time 34c indicates a change time in which a light distribution pattern is to be changed in association with each of the events, or in other words, a step change time in which the luminance of an LED 28 is to be changed in association with each of the events.

[0020] The headlight control unit 26 controls the turning on / off of the plurality of LEDs 28 individually based on the pattern instruction S1. In the present embodiment, the headlight control unit 26 decides at which of the step-change times the luminance of each of the plurality of LEDs 28 should be changed by accessing the memory unit 34, and generates an on / off instruction signal S3 instructing the LEDs 28 to be turned on or off at the predetermined step-change time.

[0021] When the headlight control unit 26 receives a pattern instruction S1 while the light distribution pattern is not switched (hereinafter, the pattern instruction S1 received at this point is also referred to as a “first pattern instruction S1a”), the headlight control unit 26 controls on / off of the plurality of LEDs 28 individually so as to switch to a light distribution pattern (hereinafter also referred to as a “first light distribution pattern”) indicated by the first pattern instruction S1a.Specifically, by accessing the storage unit 34, the headlight control unit 26 decides to change the luminance stepwise at a stepwise change time corresponding to an event (hereinafter, such an event will be referred to as a "first event") that caused the switching to the first light distribution pattern (hereinafter, such a stepwise change time will be referred to as a "first duration"), to reach the luminance (hereinafter, referred to as the "first luminance") corresponding to the first light distribution pattern. In this case, the headlight control unit 26 generates, as the on / off instruction signal S3, an on / off signal S3a instructing on / off at the stepwise change time corresponding to the event.

[0022] Additionally, when the headlight control unit 26 receives a new pattern instruction S1 in the middle of switching to a given light distribution pattern (i.e., first light distribution pattern) (hereinafter, the pattern instruction S1 received at this point is also referred to as a "second pattern instruction S1b"), the headlight control unit 26 controls on / off of the plurality of LEDs 28 individually so as to switch to a light distribution pattern (hereinafter also referred to as a "second light distribution pattern") indicated by the second pattern instruction S1b. Specifically, the headlight control unit 26 accesses the storage unit 34 and compares the priority of the first event with the priority of the event (hereinafter referred to as a "second event") that caused the switch to the second light distribution pattern.

[0023] If the priority of the second event is higher than the priority of the first event, the headlight control unit 26 decides to gradually change the luminance to reach the luminance (hereinafter referred to as "second luminance") corresponding to the second light distribution pattern in a stepwise change time (hereinafter referred to as "second duration") corresponding to the second event. In this case, the headlight control unit 26 generates, as the on / off instruction signal S3, an on / off signal S3a instructing on / off in the stepwise change time corresponding to the event. Meanwhile, if the priority of the first event is higher than the priority of the second event, the headlight control unit 26 decides to gradually change the luminance to reach the second luminance regardless of the second duration.In the present embodiment, the headlight control unit 26 decides to gradually change the luminance to reach the second luminance in the remaining time of the first duration. In this case, the headlight control unit 26 generates, as the on / off instruction signal S3, an on / off instruction signal S3b that instructs the on / off at a time that does not depend on the time of a step change corresponding to the event.

[0024] The lighting circuit 24 includes drive circuits 30 and step change controllers 32 provided for the respective LEDs 28. The drive circuits 30 provide drive currents I LD , corresponding to the respective light control signals S4, to the LEDs 28. Each control circuit 30 can perform both analog light control by adjusting the amount of the control current I LDas well as pulse width modulation (PWM) light control by varying the duty cycle of the control current I LD by controlling the control current I LD is changed at high speed, or can only perform one of the two.

[0025] Each step change controller 32 generates a light control signal S4 that changes stepwise over time in accordance with an on / off instruction signal S3 from the headlight control unit 26. Specifically, when the luminance is to be reduced, the step change controller 32 causes the light control signal S4 to change smoothly over time in a direction in which the drive current I LD decreases. Meanwhile, when the luminance is to be increased, the step change controller 32 causes the light control signal S4 to change smoothly with time in a direction in which the drive current I LDincreases.

[0026] Fig. 3 schematically illustrates a light distribution pattern formed by the vehicle headlight system 100 configured as described above. Fig. 3 illustrates a light distribution pattern formed on a virtual vertical screen arranged at a predetermined position in front of the headlight, for example, at a position 25 meters in front of the headlight.

[0027] A light distribution pattern PH is a high beam distribution pattern formed by illumination light from the headlight unit 20. The light distribution pattern PH is divided into a plurality of (eight) sub-areas PHa to PHh, and the sub-areas correspond to the respective LEDs 28. In other words, the vehicle headlight 18 can form the high beam distribution pattern PH in a region ahead of the vehicle, which is composed of the plurality of sub-areas PHa to PHh corresponding to the illumination areas of the respective LEDs 28.

[0028] Fig. 4A and Fig. 4B illustrates an example of a luminance distribution of each of the sub-areas PHa to PHh of the light distribution pattern PH. The longer a given bar, the higher the luminance of its corresponding sub-area (i.e., the longer a given bar, the higher the luminance of the LED 28 illuminating the corresponding sub-area). Fig. 4A illustrates an example of the luminance distribution of the partial areas PHa to PHh of the light distribution pattern PH formed when the high beam was changed from on to off during medium-speed driving, or in other words, when a “light change” event occurred. Fig. Figure 4B illustrates an example of the luminance distribution of the sub-areas PHa to PHh of the light distribution pattern PH formed when a leading vehicle or an oncoming vehicle is detected, or in other words, when a "target detection" event occurs. This example illustrates a case where a leading vehicle or an oncoming vehicle is detected in the sub-areas PHd and PHe. Fig. 4C and Fig. 4D illustrate examples of the luminance distribution of the partial areas PHa to PHh of the light distribution pattern PH formed when the vehicle speed was changed from medium-speed running to low-speed running and when the vehicle speed was changed from medium-speed running to high-speed running, or in other words, when a “vehicle speed change” event occurred. Fig. Figure 4E illustrates an example of the luminance distribution of the partial areas PHa to PHh of the light distribution pattern PH formed when the steering wheel was turned to the left, or in other words, when a “steering angle change” event occurred. As shown in Fig. 4A to 4E, when an event occurs, the light distribution pattern is changed in accordance with that event and the luminance of a sub-area (ie, the luminance of an LED 28 illuminating the sub-area) changes.

[0029] Fig. Figure 5 illustrates an example of a change in the luminance of an LED 28 illuminating a given partial area. In Fig. 5 the horizontal axis represents time and the vertical axis represents luminance. Fig. 5 illustrates a case where the light distribution pattern is changed at the steering angle change serving as the second event that occurred in the middle of the change of the light distribution pattern in conjunction with the light change serving as the first event (while the luminance of the LED 28 is changed).

[0030] Upon receiving a first pattern instruction S1a indicating a change to the first light distribution pattern in conjunction with the occurrence of light change, the headlight control unit 26 generates an on / off instruction signal S3a that changes the luminance stepwise to reach the target luminance in a stepwise change time (700 ms) corresponding to the light change. Based on this on / off instruction signal S3a, the stepwise change controller 32 generates a light control signal S4 that changes in 700 ms in a direction in which the drive current I LD increases. The control circuit 30 supplies the control current I LD , which corresponds to this light control signal S4, to the LED 28 and increases the luminance of the LED 28 step by step.

[0031] Upon receiving a second pattern instruction S1b indicating a change to the second light distribution pattern in conjunction with the occurrence of a steering angle change, the headlight control unit 26 accesses the storage unit 34 and checks the priorities of the light change and the steering angle change. In the present embodiment, the headlight control unit 26 decides that the priority of the light change, which is the earlier event, is higher than the priority of the steering angle change, which is the later event (see Fig. 2).

[0032] Therefore, the headlight control unit 26 generates an on / off instruction signal S3b that gradually changes the luminance to reach the target luminance of the second light distribution pattern in the remaining time of the step change time (700 ms) corresponding to the light change, regardless of the step change time (200 ms) corresponding to the steering angle change. For example, if the steering angle change occurs when 300 ms have elapsed since the light change occurred, the headlight control unit 26 generates an on / off instruction signal S3b that gradually changes the luminance to reach the target luminance of the second light distribution pattern in the remaining 400 (= 700 - 300) ms.

[0033] Based on the on / off instruction signal S3b, the step change controller 32 generates a light control signal S4 which changes in 400 ms in a direction in which the drive current ILD increases. The control circuit 30 supplies the control current I LD , which corresponds to this new light control signal S4, to the LED 28 and increases the luminance of the LED 28 gradually.

[0034] With the vehicle headlight system 100 according to the above-described embodiment, when the priority of the second event is lower than the priority of the first event, the luminance of the LED 28 is gradually changed to achieve the target luminance regardless of the second duration. In other words, when the priority of the later-occurring event is lower than the priority of the earlier-occurring event, the luminance of the LED 28 is gradually changed regardless of the time corresponding to the later-occurring event. Accordingly, by appropriately setting the priorities, a change in the luminance associated with a higher-priority event can be achieved in a target duration regardless of the later-occurring event.

[0035] So far, the present invention has been described based on one embodiment. However, this embodiment is merely illustrative, and it will be understood by those skilled in the art that various modifications can be made to the combinations of components and processing methods of the embodiment, and that such modifications also fall within the scope of the present invention. Such modifications will be described below. (First modification)

[0036] In the embodiment, a case in which the luminance is gradually changed to reach the second luminance in the remaining time of the first duration if the priority of the first event is higher than the priority of the second event was described, but this is not a limiting example. If a predetermined condition is met, even if the priority of the second event is lower than the priority of the first event, the luminance may be gradually changed to reach the second luminance in the second duration if the remaining time of the first duration is shorter than the second duration. In this case, a rapid change in the luminance of an LED can be suppressed. Examples of the predetermined condition include a case in which the first event is an event in which the plurality of off LEDs 28 are turned on (ie,Light change), and the second event is the steering angle change. When the off LEDs 28 are turned on, the driver may feel a sense of discomfort if the luminance of all LEDs 28 changes rapidly, but this can be suppressed by the modification.

[0037] The present invention has been described on the basis of embodiments with the use of specific terms, but the embodiments merely illustrate the principle and applications of the present invention, and a number of modifications of the embodiments and changes in the arrangement can be made within a scope that does not deviate from the spirit of the present invention set forth in the claims.

[0038] A vehicle headlight system according to one aspect of the present invention includes a headlight unit that combines light beams from a plurality of light-emitting elements to illuminate with a predetermined beam, a control unit that controls a change in the luminance of the plurality of light-emitting elements in accordance with an instruction from a vehicle and / or information indicative of a driving condition, and a storage unit that stores information indicating a priority of an event that causes the luminance of the plurality of light-emitting elements to be changed.In a case where a second event occurs while the luminance of the plurality of light-emitting elements is gradually changed to reach a first luminance in a first duration corresponding to a first event, the control unit gradually changes (i) the luminance of the plurality of light-emitting elements to reach the second luminance in a second duration corresponding to the second event if the priority of the second event is higher than the priority of the first event, and (ii) the luminance of the plurality of light-emitting elements to reach the second luminance regardless of the second duration if the priority of the second event is lower than the priority of the first event.

[0039] According to this aspect, when the priority of a later-occurring event is lower than the priority of an earlier-occurring event, the luminance of the light-emitting element is changed gradually regardless of the time corresponding to the later-occurring event. Accordingly, by appropriately setting the priorities, a change in the luminance associated with a higher-priority event can be achieved in a desired time period regardless of a later-occurring event.

[0040] The control unit may change the luminance of the plurality of light-emitting elements stepwise to reach the second luminance in a remaining time of the first duration if the priority of the second event is lower than the priority of the first event.

[0041] When a predetermined condition is met, even if the priority of the second event is lower than the priority of the first event, the control unit can gradually change the luminance of the plurality of light-emitting elements to reach the second luminance in the second duration if a remaining time of the first duration is shorter than the second duration. This configuration makes it possible to suppress rapid changes in the luminance of the light-emitting elements.

[0042] The predetermined condition may be that the first event is an event in which the plurality of turned-off light-emitting elements are turned on.

Claims

[1] A vehicle headlight system (100) comprising: a headlight unit (20) that combines light beams from a plurality of light-emitting elements (28) to illuminate with a predetermined beam; a control unit (26) that controls a change in the luminance of the plurality of light-emitting elements (28) in accordance with an instruction from a vehicle and / or information indicating a driving condition; and a storage unit (34) that stores information indicating a priority of an event that causes the luminance of the plurality of light-emitting elements (28) to be changed, wherein, in a case where a second event occurs while the luminance of the plurality of light-emitting elements (28) is gradually changed to reach a first luminance in a first duration corresponding to a first event, the control unit gradually changes: (i) the luminance of the plurality of light-emitting elements (28) to reach a second luminance in a second duration corresponding to the second event if the priority of the second event is higher than the priority of the first event; and (ii) the luminance of the plurality of light-emitting elements (28) to reach the second luminance regardless of the second duration if the priority of the second event is lower than the priority of the first event. [2] The vehicle headlight system (100) according to claim 1, wherein the control unit (26) changes the luminance of the plurality of light-emitting elements (28) stepwise to reach the second luminance in a remaining time of the first duration if the priority of the second event is lower than the priority of the first event. [3] The vehicle headlight system (100) according to claim 1 or 2, wherein, when a predetermined condition is satisfied, even if the priority of the second event is lower than the priority of the first event, the control unit (26) changes the luminance of the plurality of light-emitting elements (28) stepwise to reach the second luminance in the second duration if a remaining time of the first duration is shorter than the second duration. [4] The vehicle headlight system (100) of claim 3, wherein the predetermined condition is that the first event is an event in which the plurality of off-state light-emitting elements (28) are turned on.

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