CN116710323A - Light distribution control device, vehicle lamp system, and light distribution control method - Google Patents

Abstract

The light distribution control device (6) uses an Image (IMG) of an imaging device (4) based on an imaging area in front of a vehicle to control a light distribution variable lamp (2), and the light distribution variable lamp (2) can irradiate a visible light beam (L1) with variable intensity distribution to the front area. A light distribution control device (6) determines light irradiated to a front region corresponding to a predetermined high-luminance pixel included in an Image (IMG) as light to be subjected to illuminance adjustment, adjusts illuminance of the light to be subjected to illuminance adjustment so that a luminance value shown by the high-luminance pixel gradually approaches a predetermined target low luminance, and changes illuminance by a smaller amount of change when the illuminance is increased than when the illuminance is decreased during the adjustment.

Description

Light distribution control device, vehicle lamp system, and light distribution control method

Technical Field

The invention relates to a light distribution control device, a vehicle lamp system and a light distribution control method.

Background

In recent years, an ADB (Adaptive Driving Beam: adaptive high beam) control has been proposed that dynamically and adaptively controls a light distribution pattern based on a state around a vehicle. The ADB control detects the presence or absence of a dimming target located in front of the host vehicle and to which high-luminance light irradiation should be avoided, with a camera, and dims or extinguishes a region corresponding to the dimming target (for example, see patent literature 1). The dimming object may be a front vehicle such as a preceding vehicle or a oncoming vehicle. By dimming or extinguishing the area corresponding to the preceding vehicle, glare to the driver of the preceding vehicle can be reduced.

[ Prior Art literature ]

[ patent literature ]

Patent document 1 Japanese patent laid-open publication 2016-088224

Disclosure of Invention

[ problem to be solved by the invention ]

In the conventional ADB control, a front vehicle is mainly studied as a dimming target. In this regard, the present inventors have repeatedly conducted intensive studies, and as a result, found that: light reflectors such as road signs, line-of-sight guides (road markings), signs, and the like are also important dimming objects. That is, in recent years, the brightness of the vehicle lamp has been increased, and the intensity of the light reflected by the light reflector tends to be increased. Therefore, light with high brightness is reflected from the light reflector, and the risk of glare for the driver of the host vehicle increases.

The present invention has been made in view of such a situation, and an object thereof is to provide a technique for reducing glare from a light reflecting object.

[ solution for solving the technical problem ]

In order to solve the above-described problems, one aspect of the present invention is a light distribution control device that controls a light distribution variable lamp that can radiate a visible light beam with variable intensity distribution to a front region of a vehicle based on an image of an imaging device that images the front region of the vehicle. The light distribution control device determines light to be irradiated to a front region corresponding to a predetermined high-luminance pixel included in an image as light to be subjected to illuminance adjustment, and adjusts illuminance of the light to be subjected to illuminance adjustment so that a luminance value indicated by the high-luminance pixel gradually approaches a predetermined target low luminance, and changes illuminance by a smaller amount of change when the illuminance is increased during the adjustment than when the illuminance is decreased.

Another aspect of the present invention is a lamp system for a vehicle. The vehicular lamp system includes: an imaging device that images a front region of a vehicle; a variable light distribution lamp capable of radiating a visible light beam having a variable intensity distribution to a front region; and the light distribution control device of the scheme.

Another aspect of the present invention is a light distribution control method for controlling a light distribution variable lamp that irradiates a front region with a visible light beam having a variable intensity distribution based on an image of an imaging device that images the front region of a vehicle. The light distribution control method comprises the following steps: the light irradiated to the front area corresponding to the predetermined high-luminance pixel included in the image is determined as the subject light of illuminance adjustment, and the illuminance of the subject light is adjusted so that the luminance value shown by the high-luminance pixel gradually approaches the predetermined target low luminance, and the illuminance is changed by a smaller amount of change when the illuminance is increased than when the illuminance is decreased during the adjustment.

Any combination of the above components and the result of converting the expression system of the present invention between methods, apparatuses, systems, and the like are also effective as the means of the present invention.

Effects of the invention

According to the present invention, glare from a light reflector can be reduced.

Drawings

Fig. 1 is a block diagram of a vehicle lamp system according to an embodiment.

Fig. 2 (a) is a diagram showing an image obtained by forming a reference light distribution pattern. Fig. 2 (b) is a diagram showing the analysis result of the luminance analysis unit.

Fig. 3 is a diagram showing a change in illuminance of object light.

Fig. 4 is a diagram showing a change in illuminance of object light.

Fig. 5 is a diagram showing a change in illuminance of object light.

Fig. 6 is a flowchart showing an example of the light distribution control.

Fig. 7 is a diagram showing a change in illuminance of the object light in modification 1.

Fig. 8 is a diagram showing a change in illuminance of the object light in modification 2.

Fig. 9 is a flowchart showing an example of the light distribution control according to modification 2.

Detailed Description

The present invention will be described below based on preferred embodiments with reference to the accompanying drawings. The embodiments are not intended to limit the invention, but are merely examples, and all the features and combinations thereof described in the embodiments are not intended to limit the essential content of the invention. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repetitive description thereof will be omitted as appropriate. In addition, the scale or shape of the parts shown in the drawings are set cheaply for ease of illustration and are not to be construed restrictively unless specifically mentioned. In the present specification and claims, unless otherwise specified, the terms "1 st", "2 nd" and the like are used to distinguish one component from another. In the drawings, a part of members not important in description of the embodiments is omitted.

Fig. 1 is a block diagram of a vehicle lamp system according to an embodiment. In fig. 1, some of the components of the vehicle lamp system 1 are depicted as functional blocks. These functional blocks are implemented as hardware by elements or circuits represented by a CPU or a memory of a computer, and are implemented as software by a computer program or the like. Those skilled in the art will appreciate that these functional blocks can be implemented in various forms by combinations of hardware and software.

The vehicle lamp system 1 includes a light distribution variable lamp 2, an imaging device 4, and a light distribution control device 6. All of them may be incorporated in the same housing, or some of the members may be provided outside the housing. For example, the variable light distribution lamp 2, the imaging device 4, and the light distribution control device 6 are housed in a lamp room. The lamp chamber is partitioned by a lamp body having an opening on a vehicle front side and a translucent cover mounted so as to cover the opening of the lamp body. The imaging device 4 and the light distribution control device 6 may be housed in the vehicle body.

The variable light distribution lamp 2 can radiate a visible light beam L1 having a variable intensity distribution to a front region of the vehicle. The variable light distribution lamp 2 can individually change illuminance of light irradiated to a plurality of individual regions R arranged in a front region. The plurality of individual regions R are arranged in a matrix, for example. The variable light distribution lamp 2 receives information indicating the light distribution pattern PTN from the light distribution control device 6, and emits a visible light beam L1 having an intensity distribution corresponding to the light distribution pattern PTN. Thus, the light distribution pattern PTN is formed in front of the host vehicle. The light distribution pattern PTN can be understood as a 2-dimensional illuminance distribution of the irradiation pattern 902 formed on the virtual vertical screen 900 in front of the host vehicle by the variable light distribution lamp 2.

The configuration of the light distribution variable lamp 2 is not particularly limited, and includes, for example: a plurality of light sources arranged in a matrix; and a lighting circuit that independently drives the light sources to be lit. Preferable examples of the light source include semiconductor light sources such as LEDs (light emitting diodes), LDs (laser diodes), and organic or inorganic EL (electroluminescence). The individual regions R and the light sources are associated with each other, and light is emitted from the light sources individually for the individual regions R. In order to form an illuminance distribution corresponding to the light distribution pattern PTN, the variable light distribution lamp 2 may include a matrix-type pattern forming device such as a DMD (Digital Mirror Device: digital micromirror device) or a liquid crystal device, a scanning optical-type pattern forming device that scans the front of the vehicle with light source light, or the like.

The frame rate of the variable light distribution lamp 2 is, for example, 60fps. That is, the light distribution variable lamp 2 can update the light distribution pattern PTN 60 times every 1 second. In this case, the time (1 frame) for forming 1 light distribution pattern PTN by the light distribution variable lamp 2 is about 16.7 milliseconds. The resolution of the variable light distribution lamp 2, in other words, the light distribution resolution is, for example, 10 to 200 ten thousand pixels. The resolution of the light distribution variable lamp 2 means the number of unit areas in which illuminance can be independently changed in the light distribution pattern PTN. As an example, each unit region corresponds to each individual region R.

The imaging device 4 has sensitivity to the visible light region and repeatedly performs imaging of the front region of the vehicle. The imaging device 4 images the reflected light L2 of the visible light beam L1 caused by an object in front of the vehicle. The imaging device 4 may have sensitivity at least to the wavelength region of the visible light beam L1. The image IMG generated by the imaging device 4 is transmitted to the light distribution control device 6. In addition, the image IMG is also transmitted to the vehicle ECU. The vehicle ECU can use the acquired image IMG for target recognition in ADAS or automatic driving.

The image IMG acquired by the light distribution control device 6 may be RAW image data or image data obtained by performing a predetermined image processing by the imaging device 4 or another processing unit. In the following description, "image IMG based on the imaging device 4" means any of RAW image data and image-processed data. In addition, there may be a case where the two image data are not differentially expressed as "image IMG". The frame rate of the imaging device 4 is, for example, 60fps to 120fps (about 8.3 to 16.7ms per 1 frame). The resolution of the imaging device 4 is, for example, 30 to 500 ten thousand pixels.

The light distribution control device 6 controls the light irradiation from the light distribution variable lamp 2 with the image IMG based on the imaging device 4, and dynamically and adaptively controls the light distribution pattern PTN. The light distribution control device 6 may be configured by a digital processor, for example, a microcomputer including a CPU and a software program, or may be configured by an FPGA (Field Programmable Gate Array: field programmable gate array) or an ASIC (Application Specified IC: application specific integrated circuit). As an example, the light distribution control device 6 includes a luminance analysis unit 8, a pattern determination unit 10, and a lamp control unit 12. Each unit operates by executing a program held in a memory by an integrated circuit constituting the unit.

The luminance analysis unit 8 analyzes the luminance of each individual region R using the image IMG based on the imaging device 4. In the luminance analysis, for example, the luminance analysis unit 8 performs 2-valued processing on the luminance value of each pixel in the image IMG with a predetermined luminance threshold value. Then, the luminance analyzing unit 8 determines a predetermined high-luminance pixel included in the 2-valued image. The luminance analyzing section 8 sends the analysis result to the pattern determining section 10. The luminance threshold value can be set appropriately based on experiments or simulations, and the luminance analysis unit 8 is held in advance in a memory.

The pattern determination unit 10 determines the illuminance of the light irradiated to each individual region R based on the analysis result of the luminance analysis unit 8, and determines the light distribution pattern PTN formed in the front region. In the determination of the light distribution pattern PTN, the pattern determination section 10 adjusts the illuminance of light irradiated to the front region corresponding to the high-luminance pixel so that the luminance value (pixel value) shown by the high-luminance pixel included in the image IMG gradually approaches a predetermined target low luminance. The pattern determination unit 10 holds information on the target low luminance in advance in a memory. The target low luminance is a luminance that reduces glare to the driver by the reflected light from the light reflector, and the driver can visually recognize the light reflector, and can be set appropriately based on experiments or simulations. The pattern determination section 10 transmits information about the determined light distribution pattern PTN to the lamp control section 12.

The lamp control unit 12 controls the light distribution variable lamp 2 to form the light distribution pattern PTN determined by the pattern determination unit 10. For example, when the light source dimming method is analog dimming, the lamp control unit 12 adjusts the dc level of the driving current flowing through the light source. In addition, when the light source dimming method is PWM (Pulse Width Modulation: pulse Width modulation) dimming, the lamp control section 12 switches the current flowing through the light source and adjusts the ratio of the on period, thereby adjusting the average level of the driving current. In addition, when the variable light distribution lamp 2 includes a DMD, the lamp control unit 12 may control on/off switching of each mirror element constituting the DMD. In the case where the variable light distribution lamp 2 includes a liquid crystal device, the lamp control unit 12 may control the light transmittance of the liquid crystal device. Thus, the light distribution pattern PTN is formed in front of the host vehicle.

Hereinafter, the light distribution control performed by the light distribution control device 6 will be described in more detail. Fig. 2 (a) is a diagram showing an image IMG0 obtained by forming the reference light distribution pattern PTN 0. Fig. 2 (b) is a diagram showing the analysis result of the luminance analysis unit 8. Fig. 3, 4 and 5 are diagrams showing changes in illuminance of the object light. The vertical axis in fig. 3 to 5 represents the ratio of illuminance at the maximum nominal illuminance (maximum illuminance) of the variable light distribution lamp 2 to illuminance at 100%.

In an example of the light distribution control performed by the light distribution control device 6, first, the lamp control unit 12 controls the light distribution variable lamp 2 to form the reference light distribution pattern PTN0. The lamp control section 12 preferably holds information on the reference light distribution pattern PTN0. When the reference light distribution pattern PTN0 is formed, as shown in fig. 2 (a), an image IMG0 that is photographed in a state in front of the subject vehicle under formation of the reference light distribution pattern PTN0 is generated by the photographing device 4. The reference light distribution pattern PTN0 is a light distribution pattern of a fixed illuminance which does not depend on the luminance value of each pixel, that is, each individual region R. Therefore, the reference light distribution pattern PTN0 does not include a light shielding portion and a dimming portion, which will be described later. The reference light distribution pattern PTN0 is, for example, a light distribution pattern that irradiates substantially the entire imaging range of the imaging device 4 with illuminance at the maximum nominal level. In the following description, the illuminance of the reference light distribution pattern PTN0 is referred to as reference illuminance.

The luminance analyzing section 8 determines a high-luminance pixel from the image IMG0 obtained when the reference light distribution pattern PTN0 is formed. That is, the luminance analyzing unit 8 performs 2-valued processing of the luminance value on the image IMG0 using the luminance threshold value described above. In the example shown in fig. 2 (a), there are road marks 102, a preceding vehicle 104, and an opposite vehicle 106 in the front area. The road sign 102 as a light reflector is photographed as a high-luminance body by the formation of the reference light distribution pattern PTN0. In the present embodiment, the light reflector means at least 1 selected from the group consisting of the road sign 102, the line-of-sight guide sign, and the sign. Alternatively, the light reflector may be an object having a retro-reflective surface at least in a portion visible from the host vehicle. The rear light of the front vehicle 104 and the headlight of the opposite vehicle 106 are self-luminous bodies, and are thus captured as high-luminance bodies.

Therefore, as shown in fig. 2 (b), the 2-valued image IMG1 obtained by the 2-valued processing of the image IMG0 includes a high-luminance pixel 202 corresponding to the road sign 102, a high-luminance pixel 204 corresponding to the rear light of the front vehicle 104, and a high-luminance pixel 206 corresponding to the headlight of the opposite vehicle 106. Therefore, the luminance analyzing unit 8 can determine the high-luminance pixels 202 to 206 from the 2-valued image IMG 1. In addition, as an example, the high-luminance pixels 202 to 206 are each a set of a plurality of pixels.

The pattern determination unit 10 determines light irradiated to a front region (individual region R) overlapping the high-luminance pixels 202 to 206 determined by the luminance analysis unit 8 as illuminance-adjusted object light. In addition to the light irradiated to the front region corresponding to the high-luminance pixels 202 to 206, the pattern determination unit 10 of the present embodiment also includes the light irradiated to the front region corresponding to the surrounding pixels 302 to 306 located around the high-luminance pixels 202 to 206 in the object light.

The range of each peripheral pixel, in other words, the shape of each peripheral pixel is not particularly limited, but is set to, for example, a shape similar to each high-luminance pixel. The light shielding portion corresponding to the driver of the front vehicle 104 or the driver of the oncoming vehicle 106 is set in the other light distribution control. In the light distribution control according to the present embodiment, a light shielding portion corresponding to a driver of a preceding vehicle may be specified. In this case, it can be estimated that the high-luminance pixel is derived from a lamp of the preceding vehicle based on the pairing of the high-luminance pixels, that is, the case where 2 high-luminance pixels are arranged at predetermined intervals in the vehicle width direction, or the position in the 2-valued image IMG 1. Further, the position where the driver of the preceding vehicle exists can be estimated based on the position of the high-luminance pixel.

Then, as shown in fig. 3 to 5, the pattern determination unit 10 reduces the illuminance of the target light to a predetermined minimum illuminance when determining the light distribution pattern PTN formed at the first (1 st frame) after the formation of the reference light distribution pattern PTN 0. The lowest illuminance is a lower value than the illuminance corresponding to the target low luminance. In the present embodiment, the minimum illuminance is 0% (light shielding), but the present invention is not limited thereto, and can be appropriately set based on experiments or simulations. The illuminance of the light other than the subject light is maintained at, for example, a reference illuminance (maximum illuminance). The pattern determination section 10 transmits information about the determined light distribution pattern PTN to the lamp control section 12. The lamp control unit 12 controls the variable light distribution lamp 2 to form a specified light distribution pattern PTN. As a result, a light distribution pattern PTN including light shielding portions (light reducing portions, which may be also referred to as illuminance 0%) overlapping the road sign 102, the front vehicle 104, and the opposite vehicle 106 is formed in the front region. Further, by forming the light shielding portion in the front region overlapping with the high-luminance pixel derived from the light reflector, the luminance value of the high-luminance pixel becomes non-high luminance, but such a pixel is also represented as "high-luminance pixel" at low cost, which is distinguished from a pixel that is not a high-luminance pixel under formation of the reference light distribution pattern PTN 0.

Then, when determining the light distribution pattern PTN formed in the 2 nd and subsequent frames, the pattern determination unit 10 adjusts the illuminance of the subject light so that the luminance value of the high-luminance pixel gradually approaches the target low luminance. Thus, a dimming portion is formed in the light distribution pattern PTN. In addition, when determining the light distribution pattern PTN, the pattern determination unit 10 detects, in the image IMG obtained by the formation of the updated light distribution pattern PTN, the pixel value of each high-luminance pixel determined before the update of the light distribution pattern, that is, the pixel value of the pixel corresponding to the front region irradiated with the object light, and determines the next light distribution pattern PTN based on the detection result. Further, the luminance analyzing section 8 uses the image IMG to execute determination processing of high-luminance pixels. This allows detection of the appearance of a new high-luminance pixel.

In the illuminance adjustment of the subject light, the pattern determination unit 10 changes the illuminance of the subject light by a smaller amount of change when the illuminance is increased than when the illuminance is decreased. The pattern determination unit 10 of the present embodiment adjusts the illuminance of the target light by a fixed decrease amount and a fixed increase amount. The fixed decrease amount and the fixed increase amount are fixed illuminance variation amounts. The fixed reduction amount is smaller than the difference between the maximum illuminance and the minimum illuminance as an example. Further, the fixed increment is smaller than the fixed decrement. The fixed amount of decrease and the fixed amount of increase can be appropriately set based on experiments or simulations, and the pattern determination unit 10 is held in advance in the memory.

That is, when the next light distribution pattern PTN is determined, the illuminance is increased by the increased amount when the illuminance of the subject light is increased, and the illuminance is decreased by the fixed decrease amount when the illuminance of the subject light is decreased. Therefore, in a state where the luminance value of the high-luminance pixel is lower than the target low luminance, the luminance value of the high-luminance pixel gradually increases by the fixed increment amount every time the light distribution pattern PTN is updated. On the other hand, in a state where the luminance value of the high-luminance pixel is higher than the target low luminance, the luminance value of the high-luminance pixel gradually decreases by the fixed decrease amount every time the light distribution pattern PTN is updated.

The illuminance of the object light corresponding to the high-luminance pixel 202 is adjusted by the pattern determination unit 10 as follows. That is, the road sign 102, which is the basis of the high-brightness pixel 202, is a light reflector rather than a self-luminous body. Therefore, in a state where the illuminance of the object light is the lowest illuminance, the luminance value of the high-luminance pixel 202 is lower than the target low luminance. Therefore, the pattern determination unit 10 increases the illuminance of the subject light by a fixed increase amount when determining the next frame light distribution pattern PTN. As a result, as shown in fig. 3 and 4, the illuminance of the object light increases stepwise.

Then, when the luminance value of the high-luminance pixel 202 exceeds the target low luminance, the pattern determination unit 10 stops the increase in the illuminance of the target light. In the example shown in fig. 3, when the 8 th frame light distribution pattern PTN is formed, the luminance value of the high-luminance pixel 202 exceeds the target low luminance. In the example shown in fig. 4, when the 5 th frame light distribution pattern PTN is formed, the luminance value of the high-luminance pixel 202 exceeds the target low luminance. Further, when determining the light distribution pattern PTN formed after the increase of the illuminance is stopped, the pattern determination unit 10 determines the illuminance of the subject light according to different schemes depending on the magnitude of the illuminance threshold. The illuminance threshold is an illuminance corresponding to the target low luminance. That is, when the illuminance threshold light is irradiated, the luminance value of the high-luminance pixel 202 becomes the target low luminance.

Since the target low luminance is determined from the viewpoint of suppressing glare or the like from the light reflecting object, the target low luminance can be uniformly set to the same value regardless of the type of the light reflecting object. In contrast, even if the target low luminance is the same, the illuminance threshold varies according to the reflectance of visible light in each light reflector. The reflectivity of the light reflectors all have a higher tendency, but not necessarily the same. When the reflectance is relatively high, the illuminance of the object light needs to be greatly reduced in order to reduce the luminance value of the high-luminance pixel 202 to the target low luminance. Therefore, the illuminance threshold value may be a low value. On the other hand, in the case where the reflectance is relatively low, the decrease in illuminance required to decrease the luminance value of the high-luminance pixel 202 to the target low luminance may be small. Therefore, the illuminance threshold value becomes a high value. In addition, the illuminance threshold is naturally determined according to the target low luminance and the reflectance of the light reflector. Therefore, the illuminance threshold is not held in advance by the pattern determination section 10.

The pattern determination unit 10 makes the illuminance of the subject light in the sub-frame light distribution pattern PTN different between the case where the illuminance of the subject light exceeds the illuminance threshold, that is, the case where the illuminance of the subject light when the luminance value of the high-luminance pixel 202 exceeds the target low luminance is greater than or equal to the fixed reduction amount and the case where the illuminance is equal to or less than the fixed reduction amount. As described above, the information of the fixed reduction amount is held in the memory in advance. Further, the pattern determination section 10 stores illuminance of the object light determined at the time of determining the immediately preceding light distribution pattern PTN. Therefore, the magnitude of the illuminance of the target light and the fixed reduction amount can be determined.

When the illuminance of the subject light at the high-luminance pixel 202 exceeds the target low-luminance value by more than the fixed reduction amount, the pattern determination unit 10 reduces the illuminance of the subject light by the fixed reduction amount in the 9 th frame light distribution pattern PTN as shown in fig. 3. Thus, the illuminance of the object light is lower than the illuminance threshold, and therefore, the luminance value of the high-luminance pixel 202 is lower than the target low luminance. When the luminance value of the high-luminance pixel 202 is lower than the target low luminance, the pattern determination section 10 increases the illuminance of the subject light by a fixed increase amount again in the determination of the light distribution pattern PTN thereafter. Thereafter, the stepwise increase and 1 decrease in illuminance of the object light are repeated.

When the illuminance of the subject light at the time when the luminance value of the high-luminance pixel 202 exceeds the target low-luminance is equal to or less than the fixed reduction amount, the pattern determination unit 10 fixes the illuminance of the subject light in the light distribution pattern PTN of the 6 th and subsequent frames as shown in fig. 4.

The illuminance of the object light corresponding to the high-luminance pixels 204 and 206 is adjusted by the pattern determination unit 10 as follows. That is, the lamps of the front vehicle, which are the basis of the high-luminance pixels 204, 206, are self-luminous bodies. Therefore, even if the illuminance of the object light irradiated to the front region corresponding to the high-luminance pixels 204, 206 with the 1 st frame light distribution pattern PTN is reduced to the minimum illuminance, the luminance values of the high-luminance pixels 204, 206 do not change. Therefore, the pattern determination unit 10 cannot be shifted to control to increase the illuminance of the target light. As a result, as shown in fig. 5, the illuminance of the reference light irradiated to the front region corresponding to the high-luminance pixels 204, 206 is maintained at the minimum illuminance.

The lamp control unit 12 controls the variable light distribution lamp 2 to form a reference light distribution pattern PTN0 that does not include a light shielding portion or a dimming portion at the time of forming the first light distribution pattern PTN in the light distribution control. In the light distribution control thereafter, when the image IMG includes the high-luminance pixels, the light distribution pattern PTN in which the illuminance of the subject light is adjusted as described above, that is, in which a light shielding portion or a dimming portion is included in a part thereof, is formed. When the light reflector or the like, which is the basis of the high-luminance pixel, moves (including movement within the image IMG and movement outside the image IMG), the illuminance of the object light irradiated to the position where the light reflector or the like is present gradually increases each time the light distribution pattern PTN is updated, and finally returns to the reference illuminance. As an example, when the illuminance of the target light returns to the reference illuminance, the pattern specification unit 10 releases the specification of the target light with respect to the target light. When a high-luminance pixel newly appears due to movement of a light reflector or the like, the illuminance of light irradiated to a front region overlapping with the high-luminance pixel is reduced from a reference illuminance to a minimum illuminance, and then the illuminance is adjusted so that the luminance value of the high-luminance pixel gradually approaches a target low luminance.

Fig. 6 is a flowchart showing an example of the light distribution control. This flow is performed repeatedly at a predetermined timing when the ignition is turned on, for example, by a lamp switch, not shown, to instruct execution of the light distribution control.

The light distribution control device 6 controls the light distribution variable lamp 2 to form a light distribution pattern PTN (S101). In the case of forming the initial light distribution pattern of the light distribution control, the light distribution control device 6 controls the light distribution variable lamp 2 to form the reference light distribution pattern PTN0. The light distribution control device 6 generates a formation flag of the light distribution pattern PTN and holds the formation flag in the memory. Whether or not the first light distribution pattern is formed can be determined based on the presence or absence of the formation flag. In the case where the initial light distribution pattern is not formed, the light distribution variable lamp 2 is controlled to form the light distribution pattern PTN determined in the preceding routine. Next, the light distribution control device 6 acquires an image IMG from the imaging device 4 (S102), and determines whether or not there are high-luminance pixels in the image IMG (S103).

When the high-luminance pixel exists (yes in S103), the light distribution control device 6 reduces the illuminance of the subject light from the reference illuminance to the minimum illuminance. That is, the light shielding portion is determined in the light distribution pattern PTN formed next (S104). In addition, in the case where the illuminance of the object light is smaller than the reference illuminance, that is, in the case where the object light forms a dimming portion, the illuminance of the object light is maintained in this step. In the case where there is no high-luminance pixel (no in S103), the light distribution control device 6 skips step S104. Next, the light distribution control device 6 determines whether or not the light distribution pattern PTN formed in step S101 has a dimming portion (including a light shielding portion) (S105). If the light distribution pattern PTN does not have a dimming portion (no in S105), the light distribution control device 6 maintains the illuminance of the light irradiated to each individual region R at the reference illuminance (S106), and ends the present routine. In addition, when the light shielding portion is determined in step S104, the illuminance of the light shielding portion is maintained in step S106. The light distribution pattern PTN determined through step S106 is formed in step S101 in the next routine.

If the light distribution pattern PTN formed in step S101 has a dimming portion (yes in S105), the light distribution control device 6 determines whether or not there is a dimming portion in which the luminance value of the corresponding individual region R exceeds the target low luminance (S107). If there is a dimming part whose luminance value exceeds the target low luminance (yes in S107), this means that the illuminance of the corresponding dimming part exceeds the illuminance threshold, and therefore the light distribution control device 6 reduces or fixes the illuminance of the corresponding dimming part (S108). If there is no dimming portion whose luminance value exceeds the target low luminance (no in S107), the light distribution control device 6 skips step S108. Next, the light distribution control device 6 increases the illuminance of the dimming portion where the luminance value of the corresponding individual region R is equal to or lower than the target low luminance by a fixed increase amount in the light distribution pattern PTN formed in step S101 (S109), and ends the present routine. The light distribution pattern PTN determined through step S109 is formed in step S101 in the next routine. In addition, in the case where the light distribution pattern PTN has only the dimming portion whose luminance value exceeds the target low luminance, the process in step S109 is substantially omitted. The mark for forming the light distribution pattern PTN is deleted when the stop instruction of the light distribution control is made by the lamp switch or when the ignition is turned off.

As described above, the light distribution control device 6 according to the present embodiment controls the light distribution variable lamp 2 capable of radiating the visible light beam L1 having a variable intensity distribution in the forward region by the image IMG based on the imaging device 4 imaging the forward region of the vehicle. The light distribution control device 6 determines light irradiated to a front region corresponding to predetermined high-luminance pixels 202 to 206 included in the image IMG as illuminance-adjusted target light, and adjusts illuminance of the target light so that luminance values shown by the high-luminance pixels 202 to 206 gradually approach a predetermined target low luminance. In this adjustment, the pattern determination unit 10 changes the illuminance by a smaller amount than when the illuminance is reduced.

When light is irradiated from the headlight of the vehicle to the light reflecting object, light with high brightness is reflected from the light reflecting object, and a driver may feel dazzling. On the other hand, since the light reflecting object is not a self-luminous body, when light irradiation to the light reflecting object is weakened, visibility of the light reflecting object by a driver may be lowered. Therefore, when light is irradiated onto the light reflecting object, both reduction of glare from the light reflecting object and reduction of visibility to the light reflecting object are sought to be achieved.

In addition, as a technique for assisting a driving operation of a driver in recent years, research and development of an Advanced Driving Assistance System (ADAS) and an automatic driving technique are advancing. In ADAS and autopilot technologies, a situation in front of a vehicle is grasped by an imaging device such as a camera, which is an eye of a machine, and vehicle control is performed in accordance with the situation. When light of high brightness is reflected from the light reflecting object, whitening occurs in an image generated by the imaging device, and the situation may be prevented from being grasped. Further, when the light irradiation to the light reflecting object is weakened, the light reflecting object may be difficult to be detected due to the imaging device. Therefore, control of light irradiation with respect to the light reflecting object is also useful for improving the accuracy of ADAS or automatic driving techniques.

In contrast, the light distribution control device 6 according to the present embodiment adjusts the illuminance of the subject light so that the luminance value of the high-luminance pixel 202 derived from the light reflection object approaches the target low luminance. This can reduce glare from the light reflecting object while maintaining visibility for the light reflecting object.

Further, as a method for reducing glare from the light reflecting object, it is considered to suppress the average amount of light to be irradiated to the light reflecting object by combining light irradiation at 1 maximum illuminance with light irradiation at 1 or more minimum illuminance (also including the case of zero illuminance). However, in the case of this method, when light is irradiated at the maximum illuminance and when light is irradiated at the minimum illuminance, the difference in brightness of the light reflecting object becomes large, and the on/off of the light reflecting object is easily visually recognized as flickering by the driver or the photographing device. In order to make flicker not considered, it is necessary to use a light distribution variable lamp of a high frame rate (for example, 800fps or more).

In contrast, the light distribution control device 6 of the present embodiment gradually brings the luminance value of the high-luminance pixel 202 closer to the target low luminance. That is, the illuminance of the object light is changed so that the difference between the brightness of the light reflector at the maximum illuminance and the brightness at the minimum illuminance is smaller. Thus, even when the frame rate of the variable light distribution lamp is low (for example, 60 fps), flickering can be suppressed from being visually recognized by the driver or the imaging device. Therefore, glare from the light reflector can be reduced while reducing the cost of the vehicle lamp system 1. In addition, visibility of the driver or the photographing device to the light reflecting object can be further provided.

In addition, the light distribution control device 6 of the present embodiment makes the amount of change in the illuminance adjustment of the subject light smaller when the illuminance is increased than when the illuminance is decreased. The luminance value of the high-luminance pixel 202 can be repeatedly changed up and down across the target low luminance according to the resolution of the illuminance of the light distribution variable lamp 2. In contrast, by making the increase amount of the illuminance smaller than the decrease amount, the cycle of the up-down repetition can be prolonged. This can further stabilize the brightness of the light reflecting object in the vicinity of the target low brightness.

The light distribution control device 6 according to the present embodiment adjusts the illuminance of the subject light by a fixed reduction amount and a fixed increase amount smaller than the fixed reduction amount. Then, when the illuminance of the subject light is lowered so that the luminance value of the high-luminance pixel 202 is lower than the target low luminance, the illuminance of the subject light is gradually raised, and when the luminance value of the high-luminance pixel 202 exceeds the target low luminance, the illuminance of the subject light is fixed. This can further stabilize the brightness of the light reflecting object, and can simplify the light distribution control. In addition, the light distribution control device 6 according to the present embodiment fixes the illuminance of the subject light when the illuminance of the subject light at the time when the luminance value of the high-luminance pixel 202 exceeds the target low luminance is equal to or less than the fixed reduction amount. This suppresses the total amount of light irradiated to the light reflector from being excessively reduced, and thus reduces visibility of the light reflector.

Further, the light distribution control device 6 according to the present embodiment adjusts the illuminance of the subject light so that the luminance value of the high-luminance pixel approaches the target low luminance after reducing the illuminance of the subject light to the predetermined minimum illuminance. In this way, when the high-luminance pixel is used as a lamp for a preceding vehicle, the illuminance of light applied to the preceding vehicle can be reduced as quickly as possible. As a result, the possibility of causing glare to the driver of the preceding vehicle can be reduced. Further, the illuminance threshold of the light reflector such as the road sign 102 is more likely to be lower than 50%, and more likely to be about 10%. Therefore, it is possible to make the luminance value of the high-luminance pixel further approximate to the target low luminance as soon as possible: after the illuminance of the subject light is reduced to the lowest illuminance, it is gradually brought close to the illuminance threshold.

In addition to the light irradiated to the front region corresponding to the high-luminance pixels 202 to 206, the light distribution control device 6 of the present embodiment also includes the light irradiated to the front region corresponding to the surrounding pixels 302 to 306 located around the high-luminance pixels 202 to 206 in the subject light. Thus, even when the viewing angle of the variable light distribution lamp 2 is shifted from the viewing angle of the imaging device 4, the possibility that the driver of the host vehicle receives glare due to the light reflection object and the possibility that the driver of the preceding vehicle receives glare due to the light irradiation from the variable light distribution lamp 2 can be reduced. Further, the accuracy required for positioning the light distribution variable lamp 2 and the imaging device 4 can be reduced.

The embodiments of the present invention have been described in detail above. The foregoing embodiments are not merely examples of implementations of the invention. The content of the embodiment is not limited to the technical scope of the present invention, and various design changes such as modification, addition, deletion, and the like of the constituent elements can be made without departing from the scope of the invention defined in the claims. The new embodiment with the design changed has the effects of both the combined embodiment and the modification. In the foregoing embodiment, the descriptions of "this embodiment", "in this embodiment", and the like have been added to emphasize the content that can make such design changes, but the design changes are permitted even in the content that does not have such descriptions. Any combination of the above components is also effective as a solution of the present invention. The shading attached to the cross section of the drawing does not limit the material of the object to which the shading is attached.

Modification 1

Fig. 7 is a diagram showing a change in illuminance of the object light in modification 1. In the light distribution control device 6 according to the embodiment, the illuminance of the subject light is reduced to the minimum illuminance in the light distribution pattern PTN formed immediately after the high-luminance pixel is determined (1 st frame). However, the present invention is not limited thereto, and as shown in fig. 7, the illuminance of the subject light may be gradually reduced by a fixed amount of reduction from the 1 st frame.

Modification 2

The light distribution control device 6 according to the embodiment reduces the illuminance of the subject light to the lowest illuminance in the 1 st frame after the determination of the high-luminance pixel. Then, after the 2 nd frame, the light distribution pattern PTN is increased by a fixed increment every time it is updated. Then, when the luminance value of the high-luminance pixel 202 exceeds the target low luminance, the illuminance is reduced by 1 fixed reduction amount or fixed in the next frame. The light distribution control device 6 adjusts (maintains) illuminance of light other than the target light, that is, illuminance of light irradiated to a region where no object such as a light reflector is present, to (at) the reference illuminance.

When the target generated by the high-luminance pixel is eliminated for each pixel, the illuminance of the target light irradiated to the position where the target is present is gradually increased by a fixed increment for each update of the light distribution pattern PTN, and finally returned to the reference illuminance. Therefore, in order to return the illuminance of the subject light to the reference illuminance, the light distribution pattern PTN needs to be updated by the amount of fixed increment required to compensate for the difference between the current illuminance of the subject light and the reference illuminance.

Here, in a process of returning the illuminance of the object light irradiated to the position where the target object which is the base of the high-luminance pixel disappears to the reference illuminance, a situation in which the pixel corresponding to the position exceeds the target low-luminance is considered. Such a situation may occur when a target object newly appears at a position where the target object disappears (hereinafter, appropriately referred to as a 1 st situation). In the case of the 1 st condition, the light distribution control device 6 should perform the following control: when the next light distribution pattern PTN is determined, the illuminance of the object light is reduced to the lowest illuminance.

On the other hand, when the above situation is observed locally, it can be understood that: in the control in which the target is continuously present and the illuminance of the object light is gradually increased from the lowest illuminance so as to approach the target low illuminance, the illuminance value exceeds the target low illuminance (hereinafter, appropriately referred to as the 2 nd condition). In the case of the 2 nd condition, the light distribution control device 6 should perform the following control: when the next light distribution pattern PTN is determined, the illuminance of the object light is reduced by an amount of 1 fixed reduction amount or fixed.

However, the light distribution control device 6 determines the light distribution pattern PTN not by directly detecting the presence or absence of the object, but based on the luminance value of each pixel in the image IMG. Therefore, when a pixel having a luminance value higher than the target low luminance appears in the image IMG, it may be impossible to distinguish whether this is because of the 1 st condition or the 2 nd condition. Further, when discrimination is to be performed, a complication of control is incurred. Therefore, in the light distribution control as an example, the luminance of the subject is stabilized in the vicinity of the target low luminance, and when the above situation occurs, the state is determined as the 2 nd situation, and the control of reducing the illuminance of the subject light by 1 fixed reduction amount or fixing it is performed. Further, light of the lowest illuminance is irradiated in the next frame only for the front area overlapping with the high-luminance pixel detected under irradiation of the reference illuminance light.

However, when the cause of the above situation is the appearance of a new target, that is, the 1 st situation, there is a possibility that the illuminance of the subject light at this time greatly deviates from the illuminance threshold. Therefore, in the case of performing the light distribution control described above, there is a high possibility that the illuminance of the subject light is not lower than the illuminance threshold value in decreasing the illuminance by the amount of 1 fixed decrease. Therefore, the number of updates of the light distribution pattern PTN required to reduce the illuminance of the subject light to the illuminance threshold value or less increases, and there is a risk that the illuminance of the subject light is gradually increased from the time of reducing the illuminance to the lowest illuminance, as follows: it takes time before the brightness of the object is stabilized.

In contrast, the light distribution control device 6 according to the present modification performs control to increase the illuminance of the subject light by an increase amount larger than the fixed increase amount when a predetermined reset condition indicating that the target generated by the high-luminance pixel is eliminated is satisfied. Fig. 8 is a diagram showing a change in illuminance of the object light in modification 2. The light distribution control device 6 of the present modification maintains a predetermined number of resets in advance as an example of the reset condition. Then, when the number of times of increasing the illuminance of the object light by the fixed increase amount reaches the reset number, the reset condition is set to be satisfied, and the illuminance of the object light is increased by the increase amount larger than the fixed increase amount. The number of resets can be set appropriately based on experiments or simulations, and is, for example, 10 to 30 times (10 to 30 frames).

By such control, the illuminance of the subject light can be quickly returned to the reference illuminance. Further, thereby, the opportunity to execute the following control can be ensured: after detection of the high-luminance pixel, light of the lowest illuminance is irradiated. Preferably, the light distribution control device 6 sets the illuminance of the subject light to the reference illuminance when the reset condition is satisfied. This allows the illuminance of the subject light to be restored to the reference illuminance more quickly.

In the example shown in fig. 8, in the formation of the 5 th frame light distribution pattern PTN, the object is disappeared. Therefore, the light distribution control device 6 starts increasing the illuminance of the subject light gradually from the 6 th frame. Then, since the number of resets is reached when the gradual increase in illuminance of the subject light continues to the a-th frame, the illuminance of the subject light is raised to the reference illuminance in the b-th frame later. Then, in the c-th frame, the high-luminance pixel is detected in a state of being irradiated with light of the reference illuminance. Therefore, in the following d-th frame, the illuminance of the object light is reduced to the lowest illuminance.

As another example of the reset condition, the light distribution control device 6 may maintain a predetermined reset illuminance in advance. Then, when the illuminance of the object light reaches the reset illuminance, the reset condition is satisfied, and the illuminance of the object light is increased by an increase amount larger than the fixed increase amount. The reset illuminance can be set appropriately based on experiments or simulations, and for example, in the case where the illuminance is 256 gray levels, the illuminance is 50 to 70 gray levels.

Fig. 9 is a flowchart showing an example of the light distribution control according to modification 2. This flow is performed repeatedly at a predetermined timing when the ignition is turned on, for example, by a lamp switch, not shown, to instruct execution of the light distribution control.

The light distribution control device 6 controls the light distribution variable lamp 2 to form a light distribution pattern PTN (S201). In the case of forming the first light distribution pattern for light distribution control, the light distribution control device 6 controls the light distribution variable lamp 2 to form the reference light distribution pattern PTN0. The light distribution control device 6 generates a formation flag of the light distribution pattern PTN and holds the formation flag in the memory. In the case where the initial light distribution pattern is not formed, the light distribution variable lamp 2 is controlled to form the light distribution pattern PTN determined in the preceding routine. Next, the light distribution control device 6 acquires an image IMG from the imaging device 4 (S202), and determines whether or not there are high-luminance pixels in the image IMG (S203).

When the high-luminance pixel exists (yes in S203), the light distribution control device 6 reduces the illuminance of the subject light from the reference illuminance to the minimum illuminance (S204). In addition, when the illuminance of the object light is smaller than the reference illuminance, the illuminance of the object light is maintained in this step. If there is no high-luminance pixel (no in S203), the light distribution control device 6 skips step S204. Next, the light distribution control device 6 determines whether or not the light distribution pattern PTN formed in step S201 has a dimming portion (including a light shielding portion) (S205). If the light distribution pattern PTN does not have the dimming portion (no in S205), the light distribution control device 6 maintains the illuminance of the light irradiated to each individual region R at the reference illuminance (S206), and ends the present routine. In addition, when the light shielding portion is determined in step S204, the illuminance of the light shielding portion is maintained in step S206. The light distribution pattern PTN determined through step S206 is formed in step S201 in the next routine.

If the light distribution pattern PTN formed in step S201 has a dimming portion (yes in S205), the light distribution control device 6 determines whether or not there is a dimming portion satisfying the reset condition (S207). When there is a dimming portion satisfying the reset condition (yes in S207), the light distribution control device 6 increases the illuminance of the dimming portion that corresponds to the dimming portion to the reference illuminance (S208). If the dimming portion that satisfies the reset condition is not present (no in S207), the light distribution control device 6 skips step S208. Next, the light distribution control device 6 determines whether or not there is a dimming portion in which the luminance value of the corresponding individual region R exceeds the target low luminance in the light distribution pattern PTN formed in step S201 (S209).

If there is a dimming portion having a luminance value exceeding the target low luminance (yes in S209), the light distribution control device 6 reduces or fixes the illuminance of the dimming portion that corresponds to the dimming portion (S210). If there is no dimming portion whose luminance value exceeds the target low luminance (no in S209), the light distribution control device 6 skips step S210. Next, the light distribution control device 6 increases the illuminance of the dimming portion where the luminance value of the corresponding individual region R is equal to or lower than the target low luminance by a fixed increase amount in the light distribution pattern PTN formed in step S201 (S211), and ends the present routine. The light distribution pattern PTN determined through step S211 is formed in step S201 in the next routine.

(other modifications)

In the embodiment, when the illuminance of the object light when the high-luminance pixel exceeds the target low-luminance is equal to or less than the fixed reduction amount, the illuminance of the object light is fixed. However, the present invention is not limited to this, and the illuminance of the target light may be fixed when the luminance value of the high-luminance pixel 202 exceeds the target low luminance, regardless of the magnitude relation between the illuminance of the target light and the fixed reduction amount. Further, the illuminance of the object light may be decreased stepwise, and the illuminance may be fixed when the illuminance is lower than the illuminance threshold.

The invention of the above embodiment can be also specified by the following items.

(item 1)

A light distribution control device (6) for controlling a light distribution variable lamp (2) capable of radiating a visible light beam (L1) with variable intensity distribution to a front region by using an Image (IMG) based on an imaging device (4) for imaging the front region of a vehicle;

in the light distribution control device (6),

light irradiated to a front region corresponding to predetermined high-luminance pixels (202-206) included in an Image (IMG) is determined as illumination-adjusted object light, and the illumination of the object light is adjusted so that the luminance value shown by the high-luminance pixels (202-206) gradually approaches a predetermined target low luminance, and in the adjustment, the illumination is changed by a smaller amount of change when the illumination is increased than when the illumination is decreased.

(item 2)

A vehicular lamp system (1) comprising:

an imaging device (4) for imaging a front region of the vehicle,

a variable light distribution lamp (2) capable of irradiating a visible light beam (L1) with variable intensity distribution to a front region, and

the light distribution control device (6) of the scheme.

(item 3)

A light distribution control method for controlling a light distribution variable lamp (2) capable of radiating a visible light beam (L1) with variable intensity distribution to a front region by using an Image (IMG) based on an imaging device (4) for imaging the front region of a vehicle;

the light distribution control method comprises the following steps:

light irradiated to a front region corresponding to predetermined high-luminance pixels (202-206) included in an Image (IMG) is determined as illumination-adjusted object light, and the illumination of the object light is adjusted so that the luminance value shown by the high-luminance pixels (202-206) gradually approaches a predetermined target low luminance, and in the adjustment, the illumination is changed by a smaller amount of change when the illumination is increased than when the illumination is decreased.

[ Industrial availability ]

The present invention can be used for a light distribution control device, a vehicle lamp system, and a light distribution control method.

[ description of reference numerals ]

1 a vehicle lamp system, 2 a variable light, 4 a photographing device, 6 a light distribution control device, 8 a luminance analysis unit, 10 a pattern determination unit, 12 a light control unit, 202, 204, 206 high luminance pixels, 302, 304, 306 surrounding pixels.

Claims (9)

1. A light distribution control device that controls a light distribution variable lamp that can radiate visible light with variable intensity distribution to a front region of a vehicle, using an image of an imaging device that images the front region;

in the light distribution control device,

the light irradiated to a front region corresponding to a predetermined high-luminance pixel included in the image is determined as a subject light of illuminance adjustment, and illuminance of the subject light is adjusted so that a luminance value shown by the high-luminance pixel gradually approaches a predetermined target low luminance, and in the adjustment, the illuminance is changed by a smaller amount of change when the illuminance is increased than when the illuminance is decreased.

2. The light distribution control device according to claim 1, wherein,

adjusting illuminance of the subject light with a fixed decrease amount and a fixed increase amount smaller than the fixed decrease amount;

when the illuminance of the object light is lowered and the luminance value of the high-luminance pixel is lower than the target low luminance, the illuminance of the object light is raised, and when the luminance value of the high-luminance pixel exceeds the target low luminance, the illuminance of the object light is fixed.

3. The light distribution control device according to claim 2, wherein,

And fixing the illuminance of the object light when the illuminance of the object light at the time when the luminance value of the high-luminance pixel exceeds the target low luminance is equal to or less than the fixed reduction amount.

4. The light distribution control device according to any one of claims 1 to 3, wherein,

after the illuminance of the object light is reduced to a predetermined minimum illuminance, the illuminance of the object light is adjusted so that the luminance value of the high-luminance pixel approaches the target low luminance.

5. The light distribution control device according to any one of claims 1 to 4, wherein,

in addition to the light irradiated to the front region corresponding to the high-luminance pixel, the light irradiated to the front region corresponding to the surrounding pixels located around the high-luminance pixel is included in the object light.

6. The light distribution control device according to any one of claims 1 to 5, wherein,

adjusting illuminance of the subject light with a fixed decrease amount and a fixed increase amount smaller than the fixed decrease amount;

when a predetermined reset condition indicating that the object generated by the high-brightness pixel is lost is satisfied, the illuminance of the object light is increased by an increase amount larger than the fixed increase amount.

7. The light distribution control device according to claim 6, wherein,

adjusting illuminance of light other than the object light to a predetermined reference illuminance;

and setting the illuminance of the object light to the reference illuminance when the reset condition is satisfied.

8. A vehicle light system comprising:

an imaging device that images a front region of a vehicle,

a variable light distribution lamp for radiating a visible light beam with variable intensity distribution to the front region, and

the light distribution control device according to any one of claims 1 to 7.

9. A light distribution control method for controlling a light distribution variable lamp capable of radiating visible light with variable intensity distribution to a front region of a vehicle by using an image of an imaging device that images the front region;

the light distribution control method comprises the following steps:

the light irradiated to a front region corresponding to a predetermined high-luminance pixel included in the image is determined as a subject light of illuminance adjustment, and illuminance of the subject light is adjusted so that a luminance value shown by the high-luminance pixel gradually approaches a predetermined target low luminance, and in the adjustment, the illuminance is changed by a smaller amount of change when the illuminance is increased than when the illuminance is decreased.