JP2011209961A - Onboard imaging apparatus - Google Patents

Abstract

An on-vehicle imaging device capable of distinguishing a self-light-emitting light source and a reflected light source without being affected by environmental conditions such as weather is provided.
An in-vehicle imaging device mounted on a vehicle having a periodically flashing headlight, an imaging optical system, an imaging device for imaging a subject image obtained through the imaging optical system, A control unit that controls driving of the image sensor; and a signal processing unit that processes an image signal output from the image sensor, wherein the control unit synchronizes with the blinking cycle of the headlight. Controls the image capture timing so as to capture at least the image when the headlight is lit and when the headlight is lit. In addition, a distance information acquisition unit that acquires distance information to a subject is provided, and the signal processing unit determines a subject that emits light from the captured image, and distance information to the subject that emits light is predetermined. If the distance is equal to or less than the distance, a warning signal is output.
[Selection] Figure 2

Description

  The present invention relates to an on-vehicle imaging device, and more particularly to an on-vehicle imaging device suitable for use in front monitoring of a vehicle traveling at night.

2. Description of the Related Art Conventionally, a technique that can detect a preceding vehicle or an oncoming vehicle of a host vehicle at night is known.
By detecting the preceding vehicle and the oncoming vehicle, it is possible to display or warn the driver of the host vehicle, call the driver's attention, and contribute to traffic safety. Furthermore, it is possible to further contribute to traffic safety by safely controlling another in-vehicle device according to the distance to the preceding vehicle or the oncoming vehicle.

  As a technique capable of detecting a preceding vehicle and an oncoming vehicle at night, for example, in Patent Document 1, the type of light source is identified by the brightness (luminance) of a preceding vehicle, an oncoming vehicle, a light source such as a reflector that reflects light, and the like. Technology is disclosed. This is because when the preceding vehicle, the oncoming vehicle, and the reflector are at the same distance from the own vehicle, the brightness of the light from the lamp of the preceding vehicle and the oncoming vehicle and the reflected light of the light from the own vehicle are different. The light from the lamp and the reflector is used to be observed darker as the distance from the host vehicle becomes longer. In other words, the relationship between the distance from the vehicle to the light source and the luminance range in the light source region is stored in advance, and the relationship between the luminance actually observed in the image sensor and the distance from the measured vehicle to the light source is By comparing this stored relationship, the type of light source is identified.

  Further, in Patent Document 2, based on position information indicating whether the own vehicle is located in East Japan or West Japan, each of which has a different commercial power supply frequency, the light extinction cycle and the video cycle of the LED traffic light that periodically blinks are synchronized. A description of recording a video is disclosed.

JP 2008-40615 A JP 2008-250849 A

  However, in the technique disclosed in Patent Document 1, the brightness of a light source such as a taillight of a preceding vehicle, a headlamp of an oncoming vehicle, or reflected light from the host vehicle by a reflector is affected by environmental conditions such as rain and fog. receive. That is, for example, even if the distance from the host vehicle to the tail lamp of the preceding vehicle is the same distance, the tail lamp is observed with different brightness depending on environmental conditions such as sunny, cloudy, rainy, foggy. Accordingly, since the luminance of the light source is observed differently depending on the environmental conditions, the luminance different from the stored relationship may be observed depending on the environmental conditions, and the type of the light source may not be accurately identified. Further, since it is necessary to check and store the distance and the luminance range in the light source region in advance, it takes time and the cost of the entire apparatus is increased because the storage device is necessary.

  In the technique disclosed in Patent Document 2, since the commercial power source frequency and the camera frame rate are matched by determining whether the host vehicle is in eastern Japan or western Japan, the video is displayed at the turn-off timing of the LED traffic light. Although it is possible to prevent recording and failing to record the image of the LED traffic light, it is possible to prevent the recorded image from being emitted by the object (the preceding vehicle, the oncoming vehicle lamp, etc.) It cannot be identified whether the object is reflecting light (such as a reflector).

  Therefore, in view of the problems of the prior art, the present invention is not affected by environmental conditions such as the weather, and does not emit light from an object that emits light by itself (hereinafter referred to as a self-light-emitting light source). It is an object of the present invention to provide an in-vehicle imaging device that can identify an object that reflects (hereinafter referred to as a reflected light source).

  In order to solve the above problems, in the present invention, an in-vehicle imaging device mounted on a vehicle having a periodically flashing headlight, the imaging optical system and a subject obtained via the imaging optical system An image pickup device that picks up an image, a control unit that controls driving of the image pickup device, and a signal processing unit that processes an image signal output from the image pickup device, wherein the control unit blinks the headlight. In synchronism with the period, the image capturing timing is controlled so that the image capturing device captures at least the image when the headlight is turned on and when the headlight is turned off.

  As a result, it is possible to identify the subject captured in the image captured at the timing of turning off the headlight, which is periodically turned on and off and blinks, as the self-light-emitting light source. Therefore, the self-luminous light source can be identified without being affected by environmental conditions such as weather.

In addition, a distance information acquisition unit that acquires distance information to a subject is provided, and the signal processing unit determines a subject that emits light from the captured image, and distance information to the subject that emits light is predetermined. If the distance is equal to or less than the distance, a warning signal may be output. The warning signal may be superimposed on the image signal.
As a result, the driver of the own vehicle can be notified of the approach between the subject vehicle and the subject such as the preceding vehicle or the oncoming vehicle, and the possibility of collision between the subject vehicle and the subject such as the preceding vehicle or the oncoming vehicle is reduced. be able to. The predetermined distance may be set to a distance at which the collision can be avoided by confirming the warning and then responding to the driving such as the driver of the own vehicle reducing the speed. Depending on the vehicle, etc.
Further, not only the distance information between the own vehicle and the subject but also the speed information of the own vehicle is used, and the predetermined distance is shortened when the own vehicle speed is higher than when the own vehicle speed is low. It can be set. Thereby, the possibility of the collision can be further reduced.

The control unit also captures an image when the headlight is turned on, and the signal processing unit compares the captured image when the headlight is turned on and off, and determines the subject that is emitting light. You should do it.
When there is an illumination light source other than the host vehicle (headlights of other vehicles, roadside lighting, etc.), even if the headlight of the host vehicle is turned off, the reflected light source may emit light and be photographed. In such a case, if the subject captured in the image and captured in the image is identified as the self-light-emitting light source only when the headlight of the own vehicle is turned off as described above, the determination may be erroneous. Therefore, by comparing the captured images when the headlight of the host vehicle is turned on and off (takes a difference), a subject with a small difference is identified as a self-luminous light source, and a subject with a large difference is identified as a reflected light source. Thus, the possibility of the aforementioned determination error can be reduced.
That is, when the headlight is turned on, images of the self-luminous light source and the reflected light source can be captured, and when the headlight is extinguished, the image of the self-luminous light source is mainly captured. By performing the comparison, the self-light-emitting light source and the reflection light source can be accurately separated, and both the self-light-emitting light source and the reflection light source can be identified.

Further, an LED light source is used for the headlight.
By using an LED light source for the headlight, the headlight can be blinked periodically at a low cost.

In addition, a monochrome sensor is used for the image sensor.
By using a monochrome sensor for the image sensor, the present invention can be implemented at a lower cost. In the present invention, even if the image pickup device is not in color, the light-emitting light source can be identified from the acquired image when the headlight is turned off, so that the invention can be implemented even with a monochrome sensor.

  ADVANTAGE OF THE INVENTION According to this invention, the vehicle-mounted imaging device which can identify a self-light-emitting light source and a reflected light source, without being influenced by environmental conditions, such as a weather, can be provided.

It is a block diagram which shows the structure of the imaging device mounted in the vehicle in an Example, and its peripheral device. It is a flowchart of control of an imaging device. It is the figure which showed an example of the mode in front of the own vehicle at the time of LED headlights extinguishing. It is the figure which showed an example of the mode in front of the own vehicle at the time of lighting of an LED headlight. It is the graph which showed the time change of the taking-in timing of the camera in an Example, and LED headlight lighting timing. It is the schematic of the image ahead of the vehicle acquired when the LED headlight is extinguished. It is the schematic of the image ahead of the vehicle acquired when the LED headlight lights.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

FIG. 1 is a configuration diagram illustrating a configuration of an imaging device and peripheral devices mounted on a vehicle in the present embodiment.
First, the configuration of the imaging apparatus and its peripheral devices in this embodiment will be described with reference to FIG.

  In the present embodiment, an imaging apparatus having an imaging system 2 and a processing system 10, a drive system 12, an LED headlight 14, and an output system 16 are provided. The image pickup system 2 is a camera for acquiring a front shot image of a vehicle, and includes a lens 4, an image pickup element 6 that receives transmitted light from the lens 4 and outputs a shot image, and a power supply device 8. Yes.

The processing system 10 performs processing of a captured image output from the image sensor 6 and controls driving of the image sensor 6. Further, the processing system 10, the LED headlight 14, the output system 16, and signals Can be sent and received.
The drive system 12 means the accelerator and brake of the vehicle. The LED head ride 14 is a lighting device used for securing a visual recognition area in front of the vehicle in a situation where visibility is poor, such as at night, and periodically turns on and off. The output system 16 issues an alarm.

  Next, the operation of the imaging apparatus having the configuration shown in FIG. 1 will be described using the flowchart of control of the imaging apparatus shown in FIG.

  In FIG. 2, when the switch of the LED headlight 14 is turned on in step S1, the process proceeds to steps S2 and S3. The switch of the LED headlight 14 is for the vehicle driver to switch ON / OFF appropriately depending on the darkness of the surroundings. As described above, since the LED headlight 14 is repeatedly turned on and off periodically, when the LED headlight 14 is switched on, the timing at which the LED headlight 14 is turned on and the light is turned off. There is a timing.

  FIG. 3 is a diagram showing an example of a situation in front of the host vehicle when the LED headlight 14 is turned off. In FIG. 3, 20 is the own vehicle, and the LED headlight 14 of the own vehicle 20 is turned off. A preceding vehicle 40 is traveling in front of the host vehicle 20, and a tail lamp 42 of the preceding vehicle 40 is lit. A roadway outside line 30 is drawn on the road on which the host vehicle 20 travels, and a reflector 32 is provided outside the roadway outside line 30. The roadway outer line 30 and the reflector 32 are reflection light sources that do not emit light themselves and reflect light from other sources.

  FIG. 4 is a diagram illustrating an example of a situation in front of the host vehicle when the LED headlight 14 is turned on. The state shown in FIG. 4 is the same as the state shown in FIG. 3 except that the LED headlight 14 is turned on. In FIG. 4, reference numeral 24 denotes light from the LED headlight 14.

In step S2 shown in FIG. 2, an image when the LED headlight 14 is turned on is acquired. That is, in the state shown in FIG. 4, the image sensor 6 receives the transmitted light from the lens 4 and outputs a captured image. The captured image is captured by the processing system 10.
FIG. 7 is a schematic diagram of an image in front of the vehicle acquired when the LED headlight 14 is turned on, that is, in step S2.
As shown in FIG. 7, when the LED headlight 14 is turned on, not only the tail lamp 42 of the preceding vehicle 40, which is a self-luminous light source, but also the roadway outer line 30 and the reflector 32, which are reflected light sources, emit light from the LED headlight 14. Reflected and captured in the image.

In addition to step S2, an image when the LED headlight 14 is turned off is acquired in step S3. That is, in the state shown in FIG. 3, the image sensor 6 receives the transmitted light from the lens 4 and outputs a captured image. The captured image is captured by the processing system 10.
FIG. 6 is a schematic diagram of an image in front of the vehicle acquired when the LED headlight is turned off, that is, in step S3.
As shown in FIG. 6, when the LED headlight 14 is turned off, the tail lamp 42 of the preceding vehicle 40, which is a self-luminous light source, is captured in the image. Note that the roadway outer line 30 and the reflector 32, which are reflection light sources, are not captured in the image because the LED headlight 14 is off and the light from the LED headlight 14 cannot be reflected.

  FIG. 5 is a graph showing temporal changes in camera capture timing and LED headlight lighting timing in the example. In FIG. 5, the graph shown on the upper side indicates the capturing timing of the camera, and the convex portion indicates the timing when the capturing of the camera, that is, the acquisition of the image in front of the vehicle. In FIG. 5, the lower graph shows the LED headlight lighting timing, and the convex portion shows the LED headlight lighting timing.

  In step S2 and step S3 in the flowchart shown in FIG. 2, the processing system 10 synchronizes the timing of image acquisition by the image sensor 6 and the lighting timing of the LED headlight 14 to turn on the LED headlight 14. Image acquisition is performed each time and when the light is turned off. The image acquisition timing when the LED headlight 14 is turned on in step S2 is b in FIG. 5, and the image acquisition timing when the LED headlight 14 is turned off in step S3 is shown in FIG.

When step S2 and step S3 are completed in the flowchart shown in FIG. 2, the process proceeds to step S4.
In step S4, the processing system 10 takes a difference between the image obtained when the LED headlight is turned on acquired in step S2 and the image obtained when the LED headlight is turned off obtained in step S3, and the process proceeds to step S5.

In step S5, a preceding vehicle is detected from the difference taken in step S4. As shown in FIG. 6, when the LED headlight is turned off, only the self-luminous light source is captured in the image. As shown in FIG. 7, when the LED headlight is lit, the reflected light source is also captured in the image. The difference indicates only the reflected light source. Therefore, by using the difference and the images when the LED headlights are turned on and off as shown in FIG. 6 and FIG.
In this embodiment, an image in front of the vehicle is acquired when the LED headlight is turned on and off, and a preceding vehicle is detected using the difference between the images, but only when the LED headlight is turned off. It is also possible to detect a preceding vehicle having a tail lamp that is a self-luminous light source by acquiring an image. In this case, the number of image acquisitions can be reduced, and there is no need to take the difference, so the burden on the processing system can be reduced.

When step S5 ends, the process proceeds to step S6.
In step S6, the distance between the host vehicle and the preceding vehicle is measured. The distance between the host vehicle and the preceding vehicle can be estimated from the distance between the left and right tail lamps of the preceding vehicle in the image captured in step S2 or step S3, and measured by other methods such as providing a separate distance meter. May be.

When step S6 ends, the process proceeds to step S7.
In step S7, the acquired information is reflected to the driving assistance function by a command from the processing system 10.
In step S7, when the preceding vehicle is detected and the distance from the preceding vehicle is a short distance of a predetermined distance or less, a command is issued from the processing system 10 to the output system 16, and the output system 16 operates the host vehicle 20. Alerts the hand that he is approaching the preceding vehicle. Thereby, the possibility of a collision between the host vehicle and the preceding vehicle can be reduced. Further, the speed information of the host vehicle 20 is taken into the processing system 10 from the drive system 12, and a control signal is sent to the drive system when there is a high possibility of a collision with the preceding vehicle from the distance information between the speed information and the preceding vehicle. And slow down. Thereby, the possibility of a collision between the host vehicle and the preceding vehicle can be further reduced.

When step S7 ends, the process proceeds to step S8.
In step S8, it is determined whether the switch of the LED headlight 14 is ON.
If YES in step S8, that is, if the switch of the LED headlight 14 is ON, the process returns to step S2 and step S3.
If NO in step S8, that is, if the switch of the LED headlight 14 is OFF, the process ends.

According to the present invention, it is possible to identify a subject captured in an image captured at the timing of turning off an LED headlight that is periodically turned on and off as a self-luminous light source. Therefore, the self-luminous light source can be identified without being affected by environmental conditions such as weather.
Furthermore, by comparing the image captured at the timing of turning on the LED headlight and the image captured at the timing of turning off, the self-light-emitting light source and the reflected light source can be separated and identified with high accuracy.

  It can be used as an in-vehicle imaging device capable of distinguishing between a self-luminous light source and a reflected light source without being affected by environmental conditions such as weather.

2 Imaging system 4 Lens 6 Imaging element 10 Processing system (also serves as control unit and signal processing unit)
12 Drive system 14 LED headlight 16 Output system 20 Own vehicle 30 Roadway outer line 32 Reflector 40 Predecessor vehicle 42 Tail lamp

Claims (6)

An on-vehicle imaging device mounted on a vehicle having a periodically flashing headlight,
An imaging optical system, an imaging element that captures a subject image obtained through the imaging optical system, a control unit that controls driving of the imaging element, and a signal process that processes an image signal output from the imaging element And comprising
The control unit controls the image capturing timing so that the imaging device captures at least an image when the headlight is turned on and when the headlight is turned off in synchronization with the blinking cycle of the headlight. In-vehicle imaging device. Provided with distance information acquisition means for acquiring distance information to the subject,
The signal processing unit determines a subject that emits light from the captured image, and outputs a warning signal when the distance information to the subject that emits light is equal to or less than a predetermined distance. The in-vehicle imaging device according to claim 1.   The in-vehicle imaging device according to claim 2, wherein the warning signal is superimposed on the image signal.   The control unit also captures an image when the headlight is turned on, and the signal processing unit compares the captured images when the headlight is turned on and off, and determines the subject that is emitting light. The in-vehicle imaging device according to any one of claims 1 to 3.   The vehicle-mounted imaging device according to claim 1, wherein an LED light source is used for the headlight.   The in-vehicle image pickup apparatus according to claim 1, wherein a monochrome sensor is used for the image pickup element.

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