JPH08240833A - Exposure controller of camera for vehicle - Google Patents

Abstract

PURPOSE: To stably maintain the luminance level of a necessary part of a screen by detecting the luminance of a region selected from an image pickup screen and adjusting an iris or shutter so that the luminance becomes an target luminance. CONSTITUTION: A light beam passing through a lens 1 and an iris 2 is transduced into an electric signal complied with the light intensity by means of a CCD 3, amplified to a luminance signal by an amplifier 5 and given to a pulse synthesizing means 21. On the other hand, when a scanning line is within a ground area one window pulse generating means 20 generates a H level window pulse and when it is out of the ground area it generates a L level window pulse, a pulse synthesizing means 21 outputs only a luminance signal from the amplifier 5 at the time the window pulse is at H level, an averaging circuit 6 averages the luminance signal and outputs the averaged luminance value of the ground area. A comparator 7 compares the average luminance value with a target value, a drive circuit 8 adjusts an aperture area of the iris 2 according to the compared result and gives a command so that the average luminance value is coincident with the target value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of a camera mounted on a vehicle, and more particularly to iris control or shutter speed control of the camera.

[0002]

2. Description of the Related Art In general, the amount of light incident on an image sensor is controlled by a diaphragm. FIG. 21 shows, for example, Japanese Patent Publication No. 4-571.
FIG. 23 is a block diagram for explaining aperture control of the conventional image pickup element disclosed in Japanese Patent Publication No. 52-52. In the figure, 1 is a lens, 2
Is a diaphragm as an iris for adjusting the amount of light incident on the image sensor 3 which is an image pickup means, 4 is a preamplifier for amplifying the output of the image sensor 3, that is, a luminance signal corresponding to the amount of light incident through the diaphragm 2. Is an amplifier for amplifying the output of the preamplifier 4 for aperture control, 6 is an averaging circuit for obtaining the average luminance of the entire screen imaged on the image sensor 3, and 7 is this average luminance and a preset target average luminance (VT ) Is a comparator, 8 is a drive circuit, and 9 is a drive coil driven by the drive circuit 8 to change the aperture area of the diaphragm 2. Now, for example, when the diaphragm 2 is too narrow, that is, when the amount of light incident from the lens 1 is too small and a sufficient luminance signal cannot be obtained from the image sensor 3, the average luminance obtained by the averaging circuit 6 is , Which is lower than the target average brightness (VT), a command is given to the drive circuit 8 based on the comparison output of the comparator 7, the drive coil 9 is driven by the drive signal from the drive circuit 8, and the aperture 2 is opened. Be done. On the contrary, when the aperture 2 is too wide open, the image sensor 3 outputs an excessive luminance signal, and the average luminance obtained by the averaging circuit 6 is higher than the target average luminance (VT). Therefore, based on the comparison output of the comparator 7, the drive circuit 8
The diaphragm 2 is closed via the drive coil 9. As described above, the diaphragm 2 is subjected to negative feedback control so that the average luminance of the image sensor 3 matches the target average luminance (VT).

[0003]

As described above, in the conventional device, the negative feedback control is performed so that the average brightness of the entire image pickup device matches the target average brightness. Therefore, when the camera is mounted on the car to take pictures of the outside of the vehicle and various controls are to be performed based on this, if the camera is installed so that the road and the sky can be displayed on the screen at the same time, the sky can be used like in the daytime. When the luminance level of is large, the average luminance of the entire screen also becomes large. In this case, in the conventional device, the iris is controlled so that the average luminance of the entire screen becomes a constant value, so the iris is narrowed down, and the average luminance is suppressed to a constant value by reducing the luminance level as a whole. This means that the iris control changes the brightness level of the part other than the sky even though the absolute brightness level of the part other than the sky does not change. Here, what the vehicle camera is trying to obtain is information such as information about a vehicle in front, road information (white lines, etc.), and so to speak, information about portions other than the sky is required. Therefore, when trying to perform iris control using a conventional device, the brightness level of parts other than the sky (such as roads) changes according to the brightness level of the sky, making it difficult to obtain a stable brightness level image. was there. Also,
The above problems have not only occurred in the iris control device but also in the shutter speed control device.

Further, since the conventional iris control device or shutter speed control device (hereinafter referred to as an exposure control device) does not have a device failure detection function,
I could not know this even if the aperture could not be adjusted or the shutter speed could not be adjusted due to a device malfunction.

Further, it is difficult to solve the above problems with a simple structure and at a low cost.

The present invention has been made to solve the above problems, and the brightness of a necessary portion of the screen is not affected by an unnecessary high-brightness portion (for example, a clear sky) reflected on the screen. An object of the present invention is to provide an exposure control device for a vehicle-mounted camera that can keep the level stable.

Another object of the present invention is to provide an exposure control device for an on-vehicle camera which can keep the brightness level of a necessary portion of the screen more stable.

Another object of the present invention is to provide an on-vehicle camera exposure control device capable of detecting a device failure.

Another object of the present invention is to provide a highly reliable exposure control device for a vehicle camera with a simple structure and at a low cost.

[0010]

According to the present invention, a selection means for selecting a predetermined area of a screen obtained by an image pickup means, a brightness detection means for detecting the brightness of the predetermined area, and a brightness of the predetermined area are predetermined. The exposure control means adjusts the iris or the shutter so that the brightness of the predetermined area becomes the target brightness based on the target brightness.

Further, the present invention has a dividing means for vertically dividing the screen into two parts on the basis of a horizontal line on the screen obtained by a predetermined arithmetic expression based on the mounting angle and the angle of view of the camera. It is provided with a selecting means for selecting the lower screen of the two divided screens as a predetermined area.

Further, according to the present invention, a lane marking detecting means for detecting a lane marking which is drawn on a road and divides the lane, and a lane in which the vehicle is traveling are detected based on a detection output of the lane marking detecting means. Then, a selection means for selecting the area of the own lane as a predetermined area is provided.

Further, the present invention comprises a vehicle detecting means for detecting a vehicle ahead of the own vehicle and a selecting means for selecting a predetermined area including the vehicle.

Further, the present invention has threshold setting means for setting a threshold based on the brightness of the screen, and is provided with selecting means for selecting, as a predetermined area, at least an area having a brightness smaller than the threshold.

The present invention further includes a direction detecting means for detecting the direction of the own vehicle, a position detecting means for detecting the latitude and longitude of the own vehicle, and a calendar means for outputting information on the current date and time. An imaging area detecting means for detecting an area currently being imaged by the camera based on the outputs of the azimuth detecting means, the position detecting means and the calendar means and the mounting angle and the angle of view of the camera, and the calendar for storing the position information of the sun. Storage means for receiving the output of the means and outputting the current position information of the sun; determination means for determining whether or not the sun is within the image pickup area based on the detection output of the image pickup area detection means and the output of the storage means. When it is determined that the sun is present in the imaging area, a selection unit that deselects a predetermined area including the sun is provided.

Further, the present invention comprises a light amount detecting means for detecting the brightness of the sky, and an exposure control means for adjusting the iris or the shutter based on the output of the light amount detecting means.

Further, the present invention comprises a weather detecting means for detecting the weather and an adjusting means for adjusting the adjustment amount of the iris or the shutter based on the detection output of the weather detecting means.

The present invention further includes a driving state detecting means for detecting the driving state of the vehicle, a judging means for judging whether or not the vehicle is in a predetermined driving state based on a detection output of the driving state detecting means, and this judging means. When it is determined that the means is in a predetermined operating state, the iris or the shutter is adjusted to change the exposure amount of the imaging means in the increasing or decreasing direction, and the imaging means of the imaging means according to the increase or decrease of the exposure amount. A failure determination means for determining a failure based on whether the screen brightness has increased or decreased is provided.

[0019]

The exposure control device for a vehicle camera according to the present invention selects a predetermined area from the screen obtained by the image pickup means,
The iris or the shutter is adjusted so that the brightness of the predetermined area becomes the target brightness.

Further, the exposure control device for a vehicle camera according to the present invention allows the screen to move vertically with respect to a horizontal line on the screen obtained by a predetermined arithmetic expression based on the mounting angle and the angle of view of the camera. The screen is divided into two, and the lower screen of the two divided screens is selected as the predetermined area.

Further, the exposure control apparatus for a vehicle camera according to the present invention detects a lane marking that is drawn on the road and divides the lane, and the host vehicle is traveling based on the detection output of the lane marking detecting means. The vehicle lane is detected and the area of the vehicle lane is selected as the predetermined area.

The vehicle camera exposure control apparatus according to the present invention detects a vehicle ahead of the host vehicle and selects a predetermined area including this vehicle as the predetermined area.

Further, the vehicle camera exposure control apparatus according to the present invention sets a threshold value based on the brightness of the screen, and selects at least an area having a brightness smaller than the threshold value as the predetermined area.

Further, in the exposure control apparatus for a vehicle camera according to the present invention, the camera is controlled based on the azimuth of the vehicle, the latitude and longitude of the vehicle, the current date and time, the mounting angle and the angle of view of the camera. The area currently being imaged is detected, and when it is determined that the sun is present in this area, a predetermined area including the sun is deselected.

Further, the exposure control device for a vehicle camera according to the present invention changes the adjustment amount of the iris or the shutter according to the brightness of the sky.

Further, the exposure control device for a vehicle camera according to the present invention detects the weather by the weather detecting means and adjusts the adjustment amount of the iris or the shutter according to the weather.

Further, the vehicle camera exposure control apparatus according to the present invention adjusts the iris or the shutter to change the exposure amount of the image pickup means in the increasing or decreasing direction in a predetermined driving state to increase the exposure amount. Alternatively, the failure is determined by whether or not the brightness of the screen of the image pickup means is increased or decreased according to the weight reduction.

[0028]

【Example】

Example 1. In the first embodiment, a case where exposure is controlled by adjusting the iris will be described. Although not shown, the exposure control apparatus according to the first embodiment has a shutter for adjusting the exposure time of the light incident on the image pickup unit,
The shutter speed (exposure time) is fixed to a predetermined value. FIG. 1 is an example when a camera for taking a picture of the front is attached to a car. Reference numeral 10 is a car, 11 is a vehicle-mounted camera, and θ ° is a mounting angle of the camera 11. Figure 2 shows the camera 1
The screen image | photographed by 1 is shown. 12 in the figure
Is a screen taken by the camera 11, 13 is the horizon, 14 is the sky,
Reference numeral 15 is a road, and 16 is an area selected as a predetermined area.

Here, the procedure for dividing the area of the sky 14 and the area other than the sky 14 will be described. This division is performed on the basis of the position of the horizon 13 which is a horizontal line on the screen.
1 and the angle of view shown in FIG. 3 (maximum vertical and horizontal angles that can be captured by the video camera: x
°, y °). For example, assume that the camera 11 is mounted at a vertical mounting angle θ ° as shown in FIG.
The vertical angle of view of this camera is y ° as shown in FIG.
Is. Now, the screen of the camera 11 attached in this way is shown in FIG. On this screen,
Axis, the j axis is provided in the vertical direction, and assuming that the center is the origin, the coordinates of the upper right, lower right, upper left, and lower left of the screen are (1,
1), (1, -1), (-1, 1), (-1, -1). At this time, the position of the horizon 13 is given by j = 2θ / y, and of the regions divided by the horizon 13, the lower side is the ground region and the upper side is the sky region. Therefore, the average brightness of the ground area (or the peak-peak value of the brightness) is detected, and the aperture adjustment amount of the iris or the shutter speed (exposure time) is adjusted so that the brightness of the ground area matches the predetermined target brightness. ), It is possible to shoot the ground with stable brightness regardless of the brightness of the sky area.

FIG. 6 is a block diagram showing the configuration of the first embodiment. In the figure, 1 is a lens and 2 is an iris.
3 is a CCD (Charge Coupled Device) which is an image pickup means
And is composed of a plurality of pixels,
The plurality of pixels are sequentially scanned by the scanning lines to sequentially output luminance signals. Reference numeral 4 denotes a preamplifier for amplifying the output of the CCD 3, that is, a luminance signal corresponding to the amount of light incident through the diaphragm 2. Reference numeral 5 denotes an amplifier for amplifying the output of the preamplifier 4 for diaphragm control. An averaging circuit for obtaining the average brightness of the entire imaged screen, 7 is a comparator which is a comparing means for comparing this average brightness with a preset target average brightness (VT), 8 is a drive circuit, and 9 is this drive circuit. 8 is a drive coil that is driven by 8 to change the aperture area of the diaphragm 2. Reference numeral 20 is a window pulse generating means for generating a pulse signal (window pulse) of H level when the scanning line is within a predetermined area, that is, within the ground area, and L level when the scanning line is outside the ground area. The generating means 20 includes a dividing means for dividing the screen and a selecting means. Reference numeral 21 is a pulse synthesizing means for synthesizing the output signal of the amplifier 5 and the output signal of the window pulse generating means 20.

Next, the operation of the first embodiment will be described with reference to the time chart of FIG. In FIG. 7, the vertical axis represents voltage and the horizontal axis represents time. The light that has passed through the lens 1 and the iris 2 is received by the CCD 3 and converted into an electric signal corresponding to the intensity of the light. This electric signal is amplified through the preamplifier 4 and sent to the signal processing unit in the subsequent stage, and is also amplified by the amplifier 5 into a luminance signal as shown in FIG. Note that this luminance signal indicates that the larger the voltage value, the larger the luminance value. On the other hand, in the window pulse generating means 20, the dividing means divides the screen into two parts in the up-down direction with the horizon 13 as a reference according to the above-mentioned screen dividing procedure, and the selecting means defines a predetermined lower ground area in the divided screen. Select as a region.
Further, the window pulse generating means 20 is provided with the information on the scanning position of the scanning line, and the window pulse generating means 20 determines, based on the information on the scanning position of the scanning line and the information on the ground area selected by the selecting means, When the current scanning position is within the ground area, the window pulse shown in FIG. 7B is generated, which is at the H level and is outside the ground area. This window pulse is a pulse synthesizing means 21.
Given to.

The pulse synthesizing means 21 synthesizes the luminance signal from the amplifier 5 and the window pulse. The window pulse is used as a so-called mask signal in the pulse synthesizing means 21. That is, when the window pulse is at the L level, it is the information when scanning the sky region, so that the luminance signal from the amplifier 5 is prevented from being given to the averaging circuit 6, and the luminance when the window pulse is at the L level. Only the signal is supplied to the averaging circuit 6 in the subsequent stage. Therefore,
As shown in FIG. 7C, the averaging circuit 6 is supplied with only the luminance signal when the scanning line scans the ground area.
The averaging circuit 6 averages this luminance signal and outputs the average luminance value of the ground area. Here, the pulse synthesizing means 21
The averaging circuit 6 constitutes brightness detecting means for detecting the brightness of a predetermined area. The average luminance value of the ground area is input to one of the two inputs of the comparator 7. Further, at the other input terminal of the comparator 7, an appropriate average brightness value as a predetermined target brightness is a target average brightness value (VT).
Has been entered as. The comparator 7 compares the two intensities and outputs the comparison result to the drive circuit 8. In the drive circuit 8, based on the comparison result of the comparator 7,
If the average brightness value of the ground area is larger than the target average brightness value (VT), a command signal for reducing the opening area of the iris 2 by a predetermined amount is output, and conversely, the average brightness value of the ground area is the target average brightness value. If it is smaller than the value (VT), a command signal for increasing the opening area of the iris 2 by a predetermined amount is output. This command signal is given to the drive coil 9 in the subsequent stage, and the drive coil 9 receives the iris 2 based on the drive command.
The opening area of is changed by a predetermined amount. Here, the comparator 7, the drive circuit 8, and the drive coil 9 constitute exposure control means.

In the above embodiment, an example in which the opening area of the iris is changed by a predetermined amount based on the comparison result of the comparator has been described, but the difference between the average brightness value of the ground area and the target average brightness value (VT). Based on the above, the opening area of the iris may be adjusted by an amount that compensates for the difference.
That is, in place of the comparator 7, a means (a subtracter, a differential amplifier, etc.) for calculating a difference between two inputs is prepared to calculate the difference between the two, and the drive circuit 8 calculates an adjustment amount according to the difference. Alternatively, it may be calculated by map mapping and given to the drive coil 9. In this case, since the average brightness of the ground area can be corrected to the target average brightness (VT) by one-time processing, the control response can be improved.

Although the iris control based on the average luminance value has been described in the above embodiment, the iris control based on the peak value can be achieved by replacing the averaging circuit 6 with the peak value detecting circuit.

Therefore, according to the first embodiment, an image with stable luminance can be obtained without being affected by the sky region.

Although the iris control has been described in the first embodiment, the shutter speed may be controlled based on the brightness of a predetermined area with the aperture area of the iris fixed.

Example 2. FIG. 8 is an example of a screen when the front of the vehicle is photographed by the white line recognition device. 14 is the sky, 15 is a road which is a traveling road, 30 is a white line which is a division line for dividing the traveling lane, and 31 is a recognized own lane area. In the second embodiment, the ground part is recognized by the recognition method of the first embodiment, and the white line is recognized in the ground part. This white line recognition is performed by, for example, a conventional general method, by searching for the contour line from the inside, and then defining the first contour line as the white line. In the second embodiment, the ground area is further subdivided with the left and right white lines recognized in this way as boundaries, and the inside of the two white lines is set as the own lane to obtain the own lane area, and this own lane area is selected as the predetermined area. . After selecting the own lane area as the predetermined area, the same control as in the first embodiment is performed, and the negative feedback control is performed so that the brightness of the own lane area matches the target brightness.

If the white line cannot be recognized, the average brightness or the peak-peak value of the brightness of the entire initialization area of the own lane or the ground area is used as a reference. The initialization area is an area selected immediately after the power is turned on, and is an own lane area to be recognized when the vehicle is on a general straight road. Further, the initialization area may be a fixed area determined by the mounting position of the camera 11.

FIG. 9 is a block diagram showing the configuration of the second embodiment. In the figure, the same reference numerals as those used above indicate the same or corresponding portions as those used above. 32 is a preamplifier 4
A signal processing means for receiving a signal from the signal processing means 33, and a white line recognition processing means 33 as a dividing line detecting means for receiving the output from the signal processing means 32 and recognizing the white line, and the information obtained by the white line recognition processing means 33. Is a window pulse generating means 20
Given to.

Next, the operation of the second embodiment will be described with reference to the flowchart of FIG. In step S101, the white line recognition processing means 33 performs white line recognition based on the output from the signal processing means 32. In step S102, it is determined whether the white line has been correctly detected based on the white line recognition result. When the white line is correctly recognized, the process proceeds to step S103, where the own lane is defined between the right white line and the left white line, the own lane is selected as the predetermined area, and the process is ended. If the white line cannot be detected, the process proceeds to step S104, and a predetermined initialization area is selected as a predetermined area, and the process ends. After this process is completed, the same negative feedback control as in the first embodiment is performed.

Therefore, according to the second embodiment, since the predetermined area is narrowed from the ground area to the lane area divided by the white line, there is no influence other than the specific lane. Therefore, an image with more stable brightness can be obtained.

Although the predetermined area is set in the own lane in the second embodiment, the same method is applied not only in the own lane but also in any area obtained from the result of white line recognition, for example, another lane. You can

In the second embodiment, when the white line cannot be recognized, the initialization area is set as the predetermined area, but the ground area may be selected as in the first embodiment.

In the second embodiment, the iris control is performed based on the brightness of the own lane area, but the shutter speed may be controlled.

Example 3. FIG. 11 is an example of a screen when the front of the vehicle is captured by the front vehicle recognition device. 14 is empty, 1
5 is a road, 35 is a recognized front vehicle, and 36 is a peripheral region of the recognized vehicle. Here, the peripheral area 36 corresponds to a predetermined area. In the third embodiment, vehicle recognition is first performed on the screen. This is based on, for example, a method of recognizing a concentrated contour line as a vehicle as used in a general method. Next, the periphery of the recognized vehicle is selected as the predetermined area. After that, the negative feedback control is performed in the same manner as in the above-described embodiment by detecting the average brightness or the peak-peak value of the predetermined area and achieving the target brightness.

If the vehicle cannot be recognized, the method of the second embodiment may be adopted.

Therefore, according to the third embodiment, the influences other than the recognized peripheral region of the vehicle are eliminated, so that an image with more stable brightness can be obtained. In addition, the third embodiment can be easily applied to control such as tracking of a front vehicle.

In the third embodiment, the iris control is performed based on the recognized brightness of the surrounding area of the vehicle, but the aperture area of the iris may be fixed and the shutter speed may be controlled instead.

Example 4. In the fourth embodiment, the screen is divided into a plurality of areas according to the brightness, and an area excluding an unnecessary area (for example, an empty area) of these areas is selected as the predetermined area. FIG. 12A is an example of an image taken by the camera 11. First, the average luminance of the entire screen is detected, and a value obtained by adding a predetermined value is set as the threshold th. Here, p is the brightness of a pixel, n is the number of pixels, and δ is a threshold offset value for dividing an area. First, the screen is divided into a plurality of areas according to the brightness. As a result, a screen as shown in (a) is obtained. Next, using the threshold th (luminance> th, luminance <
= Th) When a plurality of areas are classified, a screen as shown in (b) is obtained. Finally, if the upper side of each divided area is not in contact with the upper side of the screen, or if the luminance does not exceed the threshold value, a predetermined area shown by hatching in (c) is obtained.

FIG. 13 is a flowchart of the above algorithm. In step S131, the screen is divided into a plurality of areas based on the brightness of the pixels. In step S132, the threshold th is set based on the brightness of the screen, and it is determined whether the brightness of each area is less than the threshold th. Then, here, a region whose brightness is less than the threshold th is selected as a predetermined region. Further, a region whose upper side is not in contact with the upper side of the screen even if the brightness is equal to or higher than the threshold value th is selected as a predetermined region in step S133. That is, in steps S132 and S133, an area in which the brightness is equal to or higher than a predetermined value among the plurality of areas and the upper side of the area is in contact with the upper side of the screen is determined to be an empty area, and is not selected. The area is selected as the predetermined area. Note that steps S132 and S133 make up a selection unit. Further, step S132 constitutes a threshold value setting means.

The above-described embodiment can be configured only with step S132. In this case, the screen is divided into two areas depending on whether or not the brightness is lower than the threshold th, and the area having the brightness lower than the threshold th is selected as the predetermined area.

Therefore, according to the fourth embodiment, the vehicle is climbed uphill,
Even if the position of the horizon changes on the screen of the camera due to downhill or pitching, it is possible to detect the sky region without fail and eliminate the adverse effect of the brightness of the sky region.

In the fourth embodiment, the iris control is performed based on the brightness of the region other than the sky region, but the aperture area of the iris may be fixed and the shutter speed may be controlled instead.

Example 5. In the fifth embodiment, the image pickup area currently being picked up by the camera 11 and the current position of the sun are obtained, and when it is determined that the sun is present in the image pickup area, an area other than the sun and its peripheral area is selected as the predetermined area. Is to do. First, the direction, latitude and longitude of the vehicle are detected by means such as a navigation system. This navigation system constitutes an azimuth detecting means and a position detecting means. The imaging area detecting means is a vehicle azimuth, a latitude,
From the longitude, the mounting angle of the camera 11, and the angle of view, the current camera 11
Obtains the imaging area where the image is captured. On the other hand, the current position of the sun is obtained as follows. The calendar means including a clock or the like outputs information on the current date and time. The storage unit that stores the position of the sun at an arbitrary date and time calculates the position of the sun at the current time based on the information from the calendar unit. The determination means determines whether or not the sun is within the image capturing area based on the image capturing area and the position of the sun. Here, when it is determined that the sun is within the imaging region, a region excluding the sun and the surrounding region is selected as the predetermined region.

This makes it possible to eliminate the influence of the sun having excessive brightness.

In this embodiment, when the sun is within the image pickup area, the adverse effect is alleviated by excluding the surrounding area, but in such a case the control may be stopped. . That is, in this case, there is provided a means for preparing a threshold value that serves as a criterion for determining whether or not the sun is in the screen, and stopping the control when the average brightness value or the peak-peak value of the screen exceeds this threshold value. Good. According to this, the configuration can be simplified as compared with the above-described embodiment.

In the fifth embodiment, the iris is controlled based on the brightness of the area other than the sun and its peripheral area. However, the aperture area of the iris may be fixed and the shutter speed may be controlled instead. .

Example 6. The sixth embodiment does not divide the screen and select a predetermined area as in the above-described embodiments, but tries to eliminate the influence of the brightness of the sky by another method. FIG. 14 is an external view showing the configuration of the sixth embodiment. 1
Reference numeral 0 is a vehicle, 11 is a vehicle-mounted camera, and 40 is a light quantity meter which is a light quantity detecting means. The photometer 40 is attached upward so that the brightness of the sky can be taken. The detection result of the light quantity meter 40 is used to correct the adjustment amount of the iris. FIG. 15 is a block diagram showing the configuration of the sixth embodiment. In the figure, the same reference numerals as those used above indicate the same or corresponding parts. 41 is a drive circuit. That is, the output of the light quantity meter 40 is given to the drive circuit 41. The drive circuit 41 has a correction unit that increases the opening area of the iris 2 as the brightness of the sky becomes brighter and increases the opening area of the iris 2 as the brightness of the sky becomes darker based on the detection output of the light meter 40. A drive command is generated based on the output of the correction means to drive the drive coil 9. As a result, the aperture area of the iris 2 changes according to the detection output of the light quantity meter 40, that is, the brightness of the sky.

FIG. 16 shows a flowchart of the sixth embodiment. In step S161, the value of the light meter 40 is read.
In step S162, the aperture area of the iris 2 is changed according to the value of this light meter.

As a result, it is possible to prevent the iris from moving unstablely, for example, the average brightness of the screen increases due to the white pattern drawn on the road such as a pedestrian crossing on the road, and the iris operates. The target brightness may be a peak-peak value instead of the average brightness.

In the sixth embodiment, the iris is controlled based on the output of the photometer, but the aperture area of the iris may be fixed and the shutter speed may be controlled instead.

Example 7. The seventh embodiment estimates the brightness of the sky by detecting the weather and eliminates the influence of the brightness of the sky. That is, when trying to project an ordinary road with an appropriate brightness level, the iris state does not change much in the daytime, in fine weather and in cloudy weather. However,
The amount of iris adjustment is obviously different in fine weather during the daytime, in rainy weather during the daytime, and in three situations at nighttime. This is because the brightness of the sky is completely different in the above three situations. Therefore, Example 7
Then, the weather is detected to determine which of the above three situations, and the adjustment amount of the iris corresponding to each is set.

FIG. 17 is a block diagram showing the structure of the seventh embodiment. In the figure, the same reference numerals as those used above indicate the same or corresponding parts. Reference numeral 42 is an adjusting means, which is provided with ON / OFF information of the wiper switch and the headlight switch. The operation of the seventh embodiment will be described with reference to the flowchart of FIG. In step S181, it is determined whether the headlight is on based on the information of the headlight switch. If the headlights are on, it is estimated that it is nighttime, so the flow advances to step S182 to select the nighttime mode. If it is determined in step S181 that the headlight is off, it can be estimated that it is daytime, and therefore the process proceeds to step S183, in which it is determined whether or not the wiper is on and whether or not the weather is fine. If the wiper is on, the routine proceeds to step S184 to select the daytime rainy weather mode, and if the wiper is off, the routine proceeds to step S185 to select the daytime sunny weather mode. A fixed iris adjustment amount that is appropriate for each of the three modes is prepared.
After any one of the three modes is selected, step S
Proceeding to 186, the command corresponding to the selected adjustment amount of the iris is output to the drive circuit 8. The drive circuit 8 drives the drive coil 9 based on this command to drive the iris.

Therefore, according to the seventh embodiment, since the headlight switch and the wiper switch are interlocked and the iris is fixed to a constant value at night and in rainy weather, respectively.
When the daytime is fine, the daytime is rainy,
Appropriate road images can be obtained even in three situations at night.

In the seventh embodiment, the headlight switch and the wiper switch compose the weather detecting means.

Further, although the headlight switch and the wiper switch are adopted as the weather detecting means in the above-mentioned embodiment, for example, a hygrometer equipped with a hygrometer for detecting the average brightness of the screen to judge whether it is day or night It may be possible to determine whether it is fine weather or rainy weather by the value of, and what kind of detecting means is used is arbitrary.

In the seventh embodiment, the iris control is performed according to the three situations. However, the aperture area of the iris is fixed, and instead the shutter speed is prepared according to the three situations and the shutter speed is controlled. You can

Example 8. The eighth embodiment provides an exposure control device capable of detecting a failure. That is, in this type of device, various controls (for example, white line recognition, front vehicle tracking, peripheral monitoring system, etc.) are performed based on the screen imaged by the camera. However, these controls are not always necessary, and it does not make much sense to perform these controls when the vehicle is stopped, for example. Therefore, in the eighth embodiment, the driving state of the vehicle is detected, and it is determined whether or not the driving state in which various controls are performed based on the screen captured by the camera.
If it is determined that the control is not required, that is, the predetermined drive state, the normal iris control is stopped and the failure diagnosis operation is performed.

FIG. 19 is a flowchart showing the operation of the eighth embodiment. First, in steps S201 to S203, it is determined whether the driving state of the vehicle is a predetermined driving state.
Here, if the side brake is on, the gear position is neutral or parking, or the vehicle speed is less than or equal to a predetermined value, it is determined that the vehicle is in a predetermined operating state, and step S
The process proceeds to step 204 and thereafter. On the other hand, if it is determined that the vehicle is not in the predetermined operating state, the process is terminated and normal control is performed. The detecting means for detecting the state of the side brake or the gear or the vehicle speed sensor constitutes an operating state detecting means, and steps S201 to S203
Constitutes a judging means.

When it is determined that the vehicle is in the predetermined operating state, the process proceeds to step S204, and the average brightness of the screen at this time is detected and stored as the first brightness V1. After memorizing,
In step S205, a command to fully open the iris 2 is output. In step S206, the iris is estimated to be fully open for a predetermined time, and in step S207 the average brightness after opening the iris is detected as the second brightness V2. In step S208, the first brightness V1 and the second brightness V1
And the second brightness V2 is compared to the first brightness V2.
If it is larger than 1, it is determined that the opening area of the iris has increased as instructed, and the process proceeds to step S209. On the contrary, in step S209, a command to fully close the iris is output, and in step S210, the iris waits for a predetermined time estimated that the iris has changed from fully open to fully closed. When a predetermined time has elapsed, the process proceeds to step S211, and the brightness after closing the iris is detected as the third brightness V3. In step S212, the first brightness V1 and the third brightness V3 are compared, and if the first brightness V1 is larger, it is determined that the iris has closed as instructed, and it is determined in step S213 that the device is normal. To do. At this time, normality may be displayed or the driver may be informed.

On the other hand, if NO in step S208 or step S212, step S214
In step S215, the failure is displayed or a warning is issued.

In the eighth embodiment, step S20
5, S209 are exposure amount changing means, and steps S204, S
207 and S211 are brightness detecting means, and step S208,
S212 constitutes failure determination means.

Therefore, according to the eighth embodiment, when the normal operation of the iris cannot be confirmed, the driver is informed of the abnormal iris operation and the control system is stopped. As a result, it is possible to prevent the control system from moving when the iris is abnormal and causing a malfunction in the subsequent image processing.

Further, since the self-diagnosis operation for this failure is performed in an operating state in which normal iris control or shutter speed control is not required, self-diagnosis can be performed without interrupting normal control.

Although the iris abnormality is detected in the eighth embodiment, the shutter speed abnormality can be detected in the same manner. In that case, the iris full open / full close command may be replaced with the shutter speed maximum / minimum command.

Example 9. Although the iris control has been described in the above-described first to eighth embodiments, the ninth embodiment will explain an example in which the first embodiment is applied to the shutter speed control.
In this case, the aperture area of the iris is fixed, and the exposure amount of the image sensor is controlled by adjusting the shutter speed (exposure time).

FIG. 20 is a block diagram showing the structure of the ninth embodiment. This control is performed at the time of sampling every predetermined time. In the figure, the same reference numerals as those used above indicate the same or corresponding parts. Reference numeral 50 is a timing pulse generating means for adjusting the shutter speed based on the output of the comparator 7. The opening area of the iris 2 is fixed.

Next, the operation will be described. Comparison means 7
Then, the average brightness obtained by the calculation and the target average brightness (V
The operation is the same as that of the first embodiment until it is compared with T).
The timing pulse generating means 50 generates a pulse signal having the same cycle as the sampling time, and this pulse signal is at the H level only during the exposure time and is at the L level in other periods.
It is a level. That is, the shutter is opened in synchronization with the rising edge of this pulse signal and is closed in synchronization with its falling edge. Now, the timing pulse generation means 50 sets the shutter speed (exposure time) in response to the comparison result of the comparison means 7.
If the target average brightness is higher, the screen is darker, so the shutter speed is slowed down by a predetermined amount to brighten the screen. This is achieved by lengthening the period in which the pulse signal is at the H level by a predetermined time.

At the next sampling, if the target average brightness is still higher than the average brightness, the timing pulse generating means 50 again slows the shutter speed by a predetermined amount. When the target average brightness is smaller than the average brightness at the next sampling, the screen is too bright, so the shutter speed is increased by a predetermined amount to darken the screen. This is achieved by shortening the period during which the pulse signal is at H level by a predetermined time.

As described above, the brightness of the screen can be controlled by controlling the shutter speed without depending on the iris.

In the ninth embodiment, the target average brightness and the average brightness are compared and the shutter speed is changed by a predetermined amount based on the comparison result. However, the shutter speed is determined based on the difference between the target average brightness and the average brightness. You may do it. In this case, the comparison means is omitted and the average brightness and the target average brightness are directly input to the shutter speed control means, and the circuit can be simplified. The shutter speed can be determined by map mapping or calculation based on experimental data.

In the ninth embodiment, the case where the first embodiment is applied to the shutter speed control has been described, but not limited to the first embodiment, all the embodiments can be easily applied to the shutter speed control.

[0083]

As described above, according to the exposure control apparatus for a vehicle camera according to the present invention, a predetermined area is selected from the screen obtained by the image pickup means, and the brightness of this predetermined area becomes the target brightness. Since the iris or shutter is adjusted, a stable brightness screen can be obtained without being affected by the brightness of the sky.

According to the vehicle camera exposure control apparatus of the present invention, the screen is moved up and down with respect to the horizontal line on the screen obtained by a predetermined arithmetic expression based on the mounting angle and the angle of view of the camera. Since the screen is divided into two in the direction and the lower screen of the two divided screens is selected as the predetermined area, the influence of the empty area of the screen is surely eliminated and a screen with stable brightness can be obtained.

Further, according to the vehicle camera exposure control apparatus of the present invention, the lane markings that are drawn on the lane and divide the traveling lane are detected, and the host vehicle travels based on the detection output of the lane marking detecting means. The own lane area is detected and the area of the own lane is selected as the predetermined area. Therefore, a screen of the own lane area having more stable brightness can be obtained.

Further, since the vehicle camera exposure control apparatus according to the present invention detects the vehicle in front of the host vehicle and selects the predetermined area including this vehicle as the predetermined area,
The brightness of the screen around the front vehicle can be more stabilized.

Further, according to the vehicle camera exposure control apparatus of the present invention, the threshold value is set based on the brightness of the screen,
Since at least the area having the brightness smaller than the threshold value is selected as the predetermined area, even if the sky area of the screen changes due to the behavior of the vehicle or the like, it is possible to surely eliminate the influence of the sky area and obtain a screen with stable brightness.

Further, according to the vehicle camera exposure control apparatus of the present invention, based on the azimuth of the host vehicle, the latitude and longitude of the host vehicle, the current date and time, the mounting angle and the angle of view of the camera. If the camera detects the area currently being imaged and it is determined that the sun is within this imaged area, the predetermined area including the sun is deselected, so the effect of the sun is eliminated and a screen with stable brightness is displayed. can get.

Further, according to the vehicle camera exposure control apparatus of the present invention, since the adjustment amount of the iris or the shutter is changed according to the brightness of the sky, stable brightness can be obtained regardless of the change of the road surface. The screen is obtained.

Further, according to the exposure control apparatus for a vehicle camera according to the present invention, the weather detecting means detects the weather,
Since the adjustment amount of the iris or the shutter is adjusted according to the weather, a screen with stable brightness can be obtained regardless of changes in the weather.

Further, according to the exposure control apparatus for a vehicle camera according to the present invention, the iris or the shutter is adjusted to change the exposure amount of the image pickup means in the increasing or decreasing direction when the vehicle is in a predetermined driving state, and the exposure amount is changed. Since the failure is determined by whether the brightness of the screen of the image pickup means is increased or decreased in accordance with the increase or decrease of the amount, the self-diagnosis can be performed without interrupting the control.

[Brief description of drawings]

FIG. 1 is an external view showing a state in which a camera is attached to a vehicle.

FIG. 2 is a diagram showing a screen shot by a camera.

FIG. 3 is a perspective view showing an angle of view of a camera.

FIG. 4 is a side view showing a mounting angle of a camera.

FIG. 5 is a diagram showing a case where coordinates are added to a screen imaged by a camera.

FIG. 6 is a block diagram showing the configuration of the first embodiment.

FIG. 7 is a time chart showing the operation of the first embodiment.

FIG. 8 is an example of a screen when the front of the vehicle is photographed by the white line recognition device.

FIG. 9 is a block diagram showing a configuration of a second embodiment.

FIG. 10 is a flowchart showing the operation of the second embodiment.

FIG. 11 is an example of a screen when the front of the vehicle is captured by the front vehicle recognition device.

FIG. 12 is an example of a screen shot by a camera.

FIG. 13 is a flowchart showing the operation of the fourth embodiment.

FIG. 14 is an external view showing a configuration of a sixth embodiment.

FIG. 15 is a block diagram showing a configuration of a sixth embodiment.

FIG. 16 is a flowchart showing the operation of the sixth embodiment.

FIG. 17 is a block diagram showing the configuration of the seventh embodiment.

FIG. 18 is a flowchart showing the operation of the seventh embodiment.

FIG. 19 is a flowchart showing the operation of the eighth embodiment.

FIG. 20 is a block diagram showing the configuration of the ninth embodiment.

FIG. 21 is a block diagram showing a conventional device.

[Explanation of symbols]

1: lens, 2: iris, 3: CCD, 4: preamplifier, 5: amplifier, 6: averaging circuit, 7: comparator, 8: drive circuit, 9: drive coil, 10: vehicle, 11: camera, 12: Screen, 13: Horizon, 14: Sky, 15: Road, 16: Selected area, 20: Window pulse generating means, 21: Pulse synthesizing means, 30: White line, 31: Own lane area, 32: Signal processing means, 33: white line recognition processing means, 35: front vehicle, 36: peripheral area, 40: light quantity meter,
41: drive circuit, 42: adjusting means, 50: timing pulse generating means

Claims (9)

[Claims] 1. A lens for condensing light, an image pickup means for outputting a signal according to the brightness of light from the lens, an iris for adjusting the intensity of light incident on the image pickup means, and the image pickup means. A shutter that adjusts the exposure time of incident light, a selection unit that selects a predetermined region of the screen obtained by the image pickup unit, a brightness detection unit that detects the brightness of the predetermined region, and a brightness of the predetermined region in advance. An exposure control device for a vehicle camera, comprising: an exposure control unit that adjusts the iris or the shutter so that the brightness of the predetermined area becomes the target brightness based on a predetermined target brightness. 2. The selecting means has a dividing means for vertically dividing the screen into two parts on the basis of a horizontal line on the screen obtained by a predetermined arithmetic expression based on a mounting angle and an angle of view of the camera. The exposure control device for a vehicle camera according to claim 1, wherein a lower screen of the screens divided into two is selected as a predetermined region. 3. A lane marking detecting means for detecting a lane marking drawn on a road to divide the lane, wherein the selecting means is a lane in which the vehicle is traveling based on a detection output of the lane marking detecting means. 2. The exposure control apparatus for a vehicle camera according to claim 1, wherein the area of the vehicle lane is detected as a predetermined area. 4. An exposure control apparatus for a vehicle camera according to claim 1, further comprising a vehicle detection means for detecting a vehicle ahead of the own vehicle, wherein the selection means selects a predetermined area including the vehicle. . 5. The vehicle according to claim 1, wherein the selecting means includes threshold setting means for setting a threshold based on the brightness of the screen, and selects at least an area having a brightness smaller than the threshold as the predetermined area. Exposure control device for camera. 6. An azimuth detecting means for detecting the azimuth of the own vehicle, and a position detecting means for detecting the latitude and longitude of the own vehicle,
An area where the camera is currently capturing an image based on the calendar means for outputting information on the current date and time, the output of the azimuth detecting means, the position detecting means and the calendar means, and the mounting angle and angle of view of the camera. An image pickup area detection means for detecting the position of the sun, a storage means for storing the position information of the sun and outputting the current position information of the sun in response to the output of the calendar means, a detection output of the image pickup area detection means and the storage means And a determination unit that determines whether or not the sun is in the imaging region based on the output, and the selection unit, when it is determined that the sun is in the imaging region, a predetermined region including the sun 2. The exposure control device for a vehicle camera according to claim 1, wherein is selected. 7. A lens for condensing light, an image pickup means for outputting a signal according to the brightness of light from this lens, an iris for adjusting the intensity of light incident on the image pickup means, and the image pickup means. A shutter for adjusting the exposure time of incident light, a light amount detecting means for detecting the brightness of the sky, and an exposure control means for adjusting the iris or the shutter based on the output of the light amount detecting means. Exposure control device for vehicle cameras. 8. A lens for condensing light, an image pickup means for outputting a signal according to the brightness of light from the lens, an iris for adjusting the intensity of light incident on the image pickup means, and the image pickup means. A shutter for adjusting the exposure time of the incident light, a weather detecting means for detecting the weather, and an adjusting means for adjusting the adjustment amount of the iris or the shutter based on the detection output of the weather detecting means. Exposure control device for vehicle cameras. 9. A lens for condensing light, an image pickup means for outputting a signal according to the brightness of light from this lens, an iris for adjusting the intensity of light incident on the image pickup means, and the image pickup means. A shutter that adjusts the exposure time of incident light, a brightness detection unit that detects the brightness of the screen of the image pickup unit, a driving state detection unit that detects the driving state of the vehicle, and a detection output of the driving state detection unit. Judgment means for judging whether or not it is in a predetermined driving state, and when the judgment means judges that it is in the predetermined driving state, the iris or the shutter is adjusted to increase or decrease the exposure amount of the image pickup means. And a failure determination for determining a failure depending on whether the brightness of the screen of the imaging means is increased or decreased according to the increase or decrease of the exposure amount. And an exposure control device for a vehicle camera.