JP4157351B2 - Automatic switching device for vehicle lighting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic switching device for a vehicle lighting device.
[0002]
[Prior art]
Such devices are known from the prior art literature.
[0003]
[Patent Document 1]
German Patent Publication No. 19523262 The device described in the above document has a sensor device that detects the brightness around the vehicle. A control device is connected to the sensor device, and the lighting device is switched by the control device depending on the detected ambient brightness. At that time, the dimming headlight and the taillight of the vehicle are switched as the lighting device. If the surroundings are not bright, the lighting device is switched on, and if the surroundings are bright, the lighting device is switched off. This known device makes it possible to switch on the lighting device with high reliability during twilight or tunnel travel.
[0004]
[Problems to be solved by the invention]
However, for example, when the field of view is poor due to fog, there is a situation where the lighting device needs to be switched on even if the surroundings are relatively bright, but it cannot be switched on with a known device.
[0005]
An object of the present invention is to detect a field of view additionally so that the lighting device can be switched on reliably even when the field of view is poor.
[0006]
[Means for Solving the Problems]
In order to solve the problem, the present invention includes a sensor device and a control device, and the sensor device detects brightness around the vehicle and a field of view around the vehicle. The detection of the height and the field of view around the vehicle are performed using the same image sensor device having a CCD image sensor having a logarithmic change characteristic curve or a CMOS image sensor and an image processing device, and the vehicle detected by the control device. Depending on the ambient brightness and on the detected field of view around the vehicle, the lighting device is switched on / off, and when the switch is switched on / off, the ambient brightness of the vehicle is Illumination when the first limit value set for the brightness of the vehicle is lower than the first limit value set for the brightness of the vehicle or when the field of view around the detected vehicle is lower than the second limit value set for the field of view around the vehicle. Equipment is in control Switched on by the device, one second limit value is set for the brightness around the vehicle, one second limit value is set for the field of view around the vehicle, One second limit value for the brightness is higher than the first limit value set for the brightness around the vehicle, and one second limit value for the surrounding field of view is Is set to be higher than the second limit value set for the field of view, the brightness of the surroundings of the vehicle exceeds one second limit value for the brightness of the surroundings of the vehicle, and the surrounding field of view is If a second limit value for the surrounding field of view is exceeded, the lighting device is switched off by the control device, suggesting that the lighting device is switched on / off by the control device. Is.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
By means of the dependent claims, advantageous embodiments and improvements of the device according to the invention are possible. In order to detect the field of view, the sensor device can easily detect the field of view by measuring from at least two different positions far away from the object and obtaining the field of view from the position.
[0008]
【Example】
Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.
[0009]
FIG. 1 shows a vehicle, for example, an automobile having a lighting device. As the lighting device, the vehicle has, for example, a dimming headlight 10 and, in some cases, a fog headlamp 12 in the front area. Within the tail region, the vehicle has a taillight 14 and possibly one or more fog taillights 16. The vehicle further includes a device for automatic switching of the lighting device, which will be described in detail below.
[0010]
The automatic switching device of the lighting device has a sensor device 20 that detects the brightness around the vehicle. The sensor device 20 is advantageously provided so as to detect the front periphery in the traveling direction of the vehicle. For example, the sensor device 20 may be provided behind the window glass in the vehicle interior space. Alternatively, the sensor device 20 may be provided in the front area of the vehicle or in one of the lighting devices. The sensor device 20 includes an image sensor 22 and an image processing device 24. The image sensor 22 is advantageously a CCD image sensor or a CMOS image sensor consisting of a number of pixels (individual photosensitive elements) arranged in rows and columns. The image sensor 22 has a non- linear, logarithmic change characteristic curve. As a result, the lighter the light, the lower the sensitivity of the image sensor 22. The advantage achieved by this characteristic curve is that the image sensor 22 can detect a wide range of different brightness, and at that time, an aperture device that blocks the portion of the light incident on the image sensor 22 is required. The point is not to. The image processing device 24 is connected to a control device 25, and the lighting device is switched by the control device 25.
[0011]
The control device 25 further processes the ambient brightness detected by the image sensor 22 and detected by the image processing device 24, and this brightness is compared with a limit value. When the lighting device is switched off, the lighting device is switched on when the ambient brightness falls below the first limit value S1. When the lighting device is switched on, the lighting device is switched off only when the ambient brightness exceeds the second limit value S2, in which case the limit value S2 is greater than the limit value S1. By doing so, it is avoided that the lighting device is repeatedly switched on and off in a short time when the ambient brightness changes only slightly. When the value falls below the first limit value S1, the dimming headlight 10 and the taillight 14 of the vehicle are switched on.
[0012]
The automatic switching device of the lighting device further includes a sensor device for detecting the field of view around the vehicle. This sensor device advantageously detects the field of view ahead of the vehicle in the direction of travel. Advantageously, the same sensor device 20 as for detecting ambient brightness is used for the detection of the field of view. At that time, the contrast of the object in front of the vehicle detected by the image sensor 22 is obtained by the image processing device 24. As the object 26, for example, a sign for a traveling road may be selected. This is because the road markings have a remarkable contrast with respect to other roads. The object 26 is detected and measured in the image of the image sensor 22 at a first time point t 1 when the vehicle and the image sensor 22 attached to the vehicle are still far away from the object 26. Then, the contrast is newly measured at a later time t2 after being tracked in the image for a predetermined time and the vehicle and the image sensor 22 attached to the vehicle are located closer to the object 26. That is, the vehicle moves toward the target 26 between the time points t2 and t1.
[0013]
Under optimal viewing conditions, i.e. in a large field of view, the results of contrast measurements at times t1 and t2 are at least approximately the same. For example, when the visibility is not good due to fog, rain, smoke, etc., the contrast at time t2 is greater than the contrast at time t1. Even when the surroundings are not bright, the contrast at time t2 is larger than the contrast at time t1. FIG. 2 shows the dependence of the measurable apparent contrast c of the object 26 on the distance from the vehicle as a function of the distance x. At a distance x = 0, the measured contrast is equal to the actual or object contrast c ₀ , ie directly equal to the surface contrast of the object 26. The larger the distance, the lower the apparent contrast c. This apparent contrast is affected by cloudiness in the atmosphere. The contrast measurable from a remote location decreases exponentially according to the following equation: ,
C (x) = c ₀ · e ^{−x / δ}
In that case, δ can be defined as a field of view. As can be easily derived from the above equation, the field of view δ can be determined using two contrast measurements at any distance x ₁ and x ₂ from the object 26 as follows:
δ = (x ₂ −x ₁ ) / ln (c (x ₁ ) / c (x ₂ )) = (x ₂ −x ₁ ) / ln (c (x ₁ )) − ln (c (x ₂ ))
That is, the obtained measured value of the field of view δ does not completely depend on the actual contrast c ₀ . Thus, information about the type of object 26 selected for measurement is not required for accurate evaluation of the measured contrast value.
[0014]
FIG. 3 shows a schematic block diagram of the sensor device 20 for visual field detection. The sensor device 20 includes an image sensor 22 and an image processing device 24. An imaging optical system 28 is provided in the beam path of light incident on the image sensor 22. The optical axes of the image sensor 22 and the imaging optical system 28 are oriented substantially parallel to the traveling direction of the vehicle. A region detected by the image sensor 22 through the imaging optical system 28 shows a conical volume body hatched in FIG. Contrast measurement is simplified by the configuration of the image sensor 22 having logarithmic change characteristics. That is, the contrast between the two different bright spots of the object 26, i.e. the ratio of the light intensities emitted from these two spots, corresponds to the difference between the signals supplied from the corresponding pixels of the image sensor 22. To do. Contrast measurement merely requires difference image formation within the image processing device 24 connected to the image sensor 22 and does not require computationally expensive division.
[0015]
In the image processing device 24, in the first step, the object 26 is selected in the image supplied by the image sensor 22, and the contrast c (x ₁ ) of the object 26 is measured. The distance x ₁ to 26 is not known. In the next step, the object 26 is tracked with images supplied from the image sensor 22 in a high speed sequence while the vehicle moves further. The immediate next method step involves a new measurement of the contrast value c (x ₂ ) of the object 26. During tracking of the object 26, the distance traveled by the vehicle (x ₁ -x ₂ ) is integrated by the image processing device 24 over time using, for example, a speed signal supplied from a vehicle tachometer using an external time clock signal. It is required by doing. This distance can also be determined by tracking the change between the two measurements of the rotational angle signal retrieved by the vehicle tire. Subsequently, the field of view δ is calculated by the aforementioned formula.
[0016]
The above-described process for visual field detection may be changed so that the visual field δ can be obtained with higher accuracy. For example, not only the contrast value is measured twice for the selected object 26, but also the contrast value may be measured many times. As a result, the curve shown in FIG. The field of view δ may be obtained with high accuracy by using the least square method. Furthermore, in addition to selecting one object 26, within each image supplied by the image sensor 22 to utilize each measurement of the field of view δ taken through a number of different objects. Thus, the contrast may be measured for a large number of objects.
[0017]
In order to find a suitable object for the measurement, the image processing device 24 needs to find a region of the image supplied from the image sensor 22 that achieves a predetermined minimum contrast. If the vehicle actually goes through the mist, in some cases the object may reach this minimum contrast only at a short distance from the vehicle. In this case, the first contrast measurement may be performed only when the distance between the object and the vehicle is short, and there may be no room for the second measurement time. In order to cope with this problem, the field of view of the image sensor 22 is preferably not the front in the traveling direction but the rear in the direction opposite to the traveling direction. Two image sensors 22 may be provided, and the field of view of one of the image sensors may be the front in the traveling direction, and the field of view of the other image sensor may be the rear in the direction opposite to the traveling direction. When there is a difficulty in the image of the image sensor 22 oriented forward, the image of the image sensor 22 oriented backward may be selected by the image processing device 24. In the image sensor 22 oriented rearward, it is preferable to select an object having the strongest contrast from all the objects for contrast measurement in the field of view. That is, the object with the strongest contrast can be seen for the longest period even when the distance between the object and the vehicle is long, and is suitable for measurement.
[0018]
An image memory 30 is assigned to the image processing device 24, and this image memory is used for buffering and storing an image supplied from the image sensor 22 for a limited time interval. In this embodiment, first, the image supplied from the image sensor 22 can be temporarily stored in the image memory 30 without being immediately processed. After the vehicle travels along a predetermined route and the image sensor 22 supplies a new image, an object suitable for contrast measurement can be selected from the latest image, and the contrast of the object can be measured. This target may be an area where the contrast of the latest image is strongest, that is, the contrast may be measured prior to the selection of the target . Runode using the image sensor 22 of the logarithmic change in the characteristic curve, the strongest target contrast can be obtained with little computational cost. The object contrast c (x ₂ ) in the latest image is temporarily stored and the selected object is identified in the previous image. This identification can be performed by back-tracking the object using a number of temporarily formed images similarly recorded in the image memory 30. Alternatively, cross-correlation techniques may be used for this purpose. After obtaining the object in the previous image, the contrast of this object is obtained and the field of view δ is obtained by the above formula. This method can be used immediately even when visibility is poor. That is, the object in the previous image selected in the latest image can be immediately identified even if the contrast is very small.
[0019]
The field of view δ determined as described above by the image processing device 24 is supplied to the control device 25 and further processed by the control device, and the field of view δ is compared with a limit value. If the lighting device is switched off, it is switched on when the field of view δ falls below the limit value S3. When the illumination device is switched on, it is switched off only when the field of view δ exceeds another limit value S4, which limit value S4 is higher than the limit value S3. By doing so, it is possible to prevent the lighting device from being repeatedly switched on / off in a short time when the field of view changes. In the field of view δ below the limit value S3, the fog headlamp 12 and / or the at least one fogtail lamp 16 may be switched on in addition to the dimming headlight 10 and the taillight 14, depending on the device. . Multiple limit values may be defined. In this case, for the first limit value S3 of the different field of view δ, only the dimming headlight 10 and the taillight 14 are first switched on and the field of view δ below another limit value S3 ′ smaller than the limit value S3. Then, the fog headlamp 12 and / or at least one fogtail lamp 16 may additionally be switched on. Alternatively or additionally, the light distribution formed by each lighting device, in particular the dimming headlight 10 and / or the fog headlight 12, may be changed when the field of view δ is poor. Good. For example, the light distribution in a case where the field of view is poor may be changed by widening the illuminated part or narrowing the irradiation width.
[0020]
If the lighting device is switched off, this lighting device is switched on by the device when the ambient brightness is below the limit value S1 or the field of view δ is below the limit value S3. If the lighting device is switched on, the lighting device is switched off only if the ambient brightness exceeds the limit value S2 and the field of view δ exceeds the limit value S4.
[0021]
Additionally, the maximum possible vehicle speed may be limited depending on the determined field of view δ. If the vehicle is equipped with a speed control device, the speed control device may automatically adapt the vehicle speed depending on the field of view, i.e., the speed decreases as the field of view deteriorates. It is good to do so.
[0022]
【The invention's effect】
According to the present invention, it is possible to obtain a remarkable effect that the visual field is additionally detected and the lighting device can be switched on reliably even when the visual field is poor. According to the present invention, it is possible to easily configure the device by the configuration in which ambient brightness is detected and the field of view is detected using the same sensor device.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a vehicle and a traffic situation ahead of the vehicle. FIG. 2 is an apparent contrast of an object depending on a distance between the object and the sensor device. FIG. 3 is a diagram of a sensor device configuration for detecting a field of view. Schematic [Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Dimming headlight 12 Fog headlamp 14 Tail light 16 Fog tail light 20 Sensor apparatus 22 Image sensor 24 Image processing apparatus 25 Control apparatus 26 Object 28 Imaging optical system 30 Image memory

Claims (5)

In an automatic switching device for a vehicle lighting device,
A sensor device (20) and a control device (25);
The sensor device (20) detects the brightness around the vehicle and the field of view around the vehicle. At the time of detection, the detection of the brightness around the vehicle and the detection of the field around the vehicle are logarithmic change characteristics. Using the same sensor device (20) having a CCD image sensor or CMOS image sensor (22) having a curve and an image processing device (24),
The control device (25) switches the lighting devices (10, 12, 14, 16) depending on the detected brightness around the vehicle and depending on the field of view around the detected vehicle. On / off,
When the switch is turned on / off, the brightness around the vehicle falls below a first limit value (S1) set for the brightness around the vehicle, or the detected field around the vehicle Is below the second limit value (S3) set for the field of view around the vehicle, the lighting device (10, 12, 14, 16) is switched on by the control device (25), and the vehicle One second limit value (S2) is set for the ambient brightness, and one second limit value (S4) is set for the field of view around the vehicle. One second limit value (S2) for the brightness of the vehicle is higher than the first limit value (S1) set for the brightness around the vehicle, and one second limit value (S1) for the surrounding field of view is set. A limit value of 2 (S4) is set for the field of view around the vehicle. Been optionally be set higher than the second limit value (S3),
The brightness of the surroundings of the vehicle exceeds one second limit value (S2) for the brightness of the surroundings of the vehicle, and the surrounding field of view has one second limit value (S4) for the surrounding field of view. If the lighting device (10, 12, 14, 16) is switched off by the control device (25), the lighting device (10, 12, 14, 16) A device for automatic switching of a vehicle lighting device, which is switched on and off by the control device (25).   Depending on the field of view, at least one additional vehicle lighting device (12, 16), for example at least one fog headlamp (12) and / or at least one fog tail lamp ( 16. The device for automatic switching of a lighting device for a vehicle according to claim 1, wherein 16) is switched.   3. The device for automatic switching of a vehicle lighting device according to claim 1, wherein the light distribution formed by the at least one lighting device (10, 12) is changed by the control device (25) depending on the field of view. For sight detection, using a sensor device (20), the contrast in one target (26), away from the target (26), measured from at least two different positions, from said the measurement The device for automatic switching of a lighting device for a vehicle according to any one of claims 1 to 3, wherein a field of view is required. Each contrast value measured, using the ratio of the difference between each distance between each position and the target (26), automatic switching apparatus of a lighting device for a vehicle according to claim 4, wherein the field of view is detected.

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