JP2005073296A - Exposure control apparatus for on-vehicle camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure control apparatus for an on-vehicle camera that is capable of self-diagnosis of a fault therein. <P>SOLUTION: The exposure control apparatus comprises a decision means for deciding whether it is a predetermined driving state on the basis of a detection output from a driving state detecting means, an exposure change means for changing so as to increase or decrease an exposure of an image pickup means by adjusting an exposure adjusting means when the decision means decides that it is the predetermined driving state, and a fault deciding means for deciding a fault according to whether luminance of a picture in the image pickup means is increased or decreased in accordance with the increase or decrease of the exposure. In the predetermined driving state, the exposure adjusting means is adjusted to change the exposure of the image pickup means to increase or decrease, and the fault is decided according to whether the luminance of the picture in the image pickup means is increased or decreased in accordance with the increase or decrease of the exposure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to control of a camera attached to a vehicle, and more particularly to iris control or shutter speed control of the camera.

In general, the amount of light incident on the image sensor is controlled by a diaphragm. FIG. 21 is a block diagram for explaining the aperture control of the conventional image sensor shown in Patent Document 1, for example. In the same figure, 1 is a lens, 2 is an iris as an iris for adjusting the amount of light incident on the image pickup device 3 as an image pickup means, and 4 is an output of the image pickup device 3, that is, depending on the amount of light incident through the stop 2. 5 is an amplifier for amplifying the output of the preamplifier 4 for aperture control, 6 is an averaging circuit for calculating the average luminance of the entire image formed on the image sensor 3, and 7 is the average luminance. A comparator for comparing with a preset target average luminance (VT), 8 is a drive circuit, and 9 is a drive coil that is driven by the drive circuit 8 and changes the aperture area of the diaphragm 2.
Now, for example, when the aperture 2 is in an excessive aperture state, that is, in a state where 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 Since the value is lower than the target average luminance (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 diaphragm 2 is opened. It is. On the contrary, when the diaphragm 2 is in an excessively open state, an excessive luminance signal is output from the image sensor 3, and the average luminance obtained by the averaging circuit 6 is higher than the target average luminance (VT). Therefore, the diaphragm 2 is closed via the drive circuit 8 and the drive coil 9 based on the comparison output of the comparator 7. 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).

Japanese Examined Patent Publication No. 4-57152

As described above, in the conventional apparatus, the negative feedback control is performed so that the average luminance of the entire image sensor matches the target average luminance.
Therefore, when taking a picture of the outside of the car with the camera mounted on it and performing various controls based on it, installing the camera so that the road and the sky are displayed on the screen at the same time will cause the sky to appear as if it is clear in the daytime. When the brightness level of is high, the average brightness of the entire screen is also increased. In this case, since the iris is controlled so that the average luminance of the entire screen becomes a constant value in the conventional apparatus, 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 although the absolute luminance level of the portion other than the sky has not changed, the luminance level of the portion other than the sky changes due to the iris control. Here, what is to be obtained by the vehicular camera is information such as information on the vehicle ahead, road information (white line, etc.), and so to speak, information other than the sky is required.
Therefore, when performing iris control using a conventional device, the brightness level of the sky other than the sky (such as a road) changes according to the brightness level of the sky, and it is difficult to obtain an image with a stable brightness level. was there.
Further, the above-mentioned problem has the same problem not only in the iris control device but also in the shutter speed control device.

Further, since conventional iris control devices or shutter speed control devices (hereinafter referred to as exposure control devices) do not have a device failure detection function, the iris cannot be adjusted or the shutter speed cannot be adjusted due to device failure. Even in such a state, I could not know this.
In order to solve the above-described problems, an object of the present invention is to provide an in-vehicle camera exposure control device capable of self-diagnosis of a device failure.

  An exposure control apparatus for a vehicle camera according to the present invention includes a lens that collects light, an imaging unit that outputs a signal according to the luminance of light from the lens, and an exposure amount adjustment that adjusts an exposure amount of the imaging unit. Brightness detection means for detecting the brightness of the screen of the imaging means, driving state detection means for detecting the driving state of the vehicle, and whether or not a predetermined driving state is based on the detection output of the driving state detection means And an exposure amount changing unit that adjusts the exposure amount adjusting unit to change the exposure amount of the imaging unit in the increasing or decreasing direction when it is determined that the determining unit is in the predetermined operating state. And failure determination means for determining a failure depending on whether or not the brightness of the screen of the imaging means has increased or decreased in accordance with the increase or decrease of the exposure amount.

  According to the vehicle camera exposure control apparatus of the present invention, the exposure amount adjustment means is adjusted in a predetermined driving state to change the exposure amount of the imaging means in the increase or decrease direction, thereby increasing or decreasing the exposure amount. Accordingly, since the failure is determined based on whether the brightness of the screen of the imaging means has increased or decreased, self-diagnosis can be performed without interrupting the control.

Embodiment 1 FIG.
In the first embodiment, a description will be given of controlling exposure by adjusting an iris. Although not shown, the exposure control apparatus of the first embodiment has a shutter that adjusts the exposure time of light incident on the imaging means, and the shutter speed (exposure time) is fixed to a predetermined value. ing.
FIG. 1 shows an example when a camera for taking a picture of the front is attached to a car. 10 is a car, 11 is an in-vehicle camera, and θ ° is an attachment angle of the camera 11. FIG. 2 shows a screen shot by the camera 11. In the figure, 12 is a screen taken by the camera 11, 13 is a horizon, 14 is sky, 15 is a road, and 16 is a selected area as a predetermined area.

Here, a 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. The position of the horizon 13 is determined by the mounting angle of the camera 11 and the angle of view shown in FIG. The maximum angle in the vertical and horizontal directions that can be calculated: x °, y °).
For example, assume that the camera 11 is mounted at a vertical mounting angle θ ° as shown in FIG. The vertical field angle of this camera is y ° as shown in FIG. Now, the screen of the camera 11 attached in this way is shown in FIG. On this screen, if the horizontal axis is the i axis and the vertical direction is the j axis, and 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 among the areas divided by the horizon 13, the lower side is the ground area and the upper side is the empty area.
Accordingly, the average brightness (or the peak-peak value of the brightness) of the ground area is detected, and the iris aperture adjustment amount or the shutter speed (exposure time) is set so that the brightness of the ground area matches the predetermined target brightness. ) Can be taken with stable brightness regardless of the brightness of the sky region.

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. Reference numeral 3 denotes a CCD (Charge Coupled Device), which is an image pickup means, which is composed of a plurality of pixels. The plurality of pixels are scanned by scanning lines to sequentially output luminance signals. Reference numeral 4 denotes a preamplifier that amplifies a luminance signal corresponding to the output of the CCD 3, that is, the amount of light incident through the aperture 2, 5 an amplifier that amplifies the output of the preamplifier 4 for aperture control, and 6 is connected to the image sensor 3. An average circuit for calculating the average luminance of the entire imaged screen, 7 is a comparator which is a comparison means for comparing this average luminance with a preset target average luminance (VT), 8 is a drive circuit, and 9 is this drive circuit. 8 is a drive coil that is driven at 8 and changes the aperture area of the diaphragm 2. Reference numeral 20 denotes window pulse generating means for generating a pulse signal (window pulse) of H level when the scanning line is in 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. A pulse synthesizing unit 21 synthesizes the output signal of the amplifier 5 and the output signal of the window pulse generating unit 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 passing through the lens 1 and the iris 2 is received by the CCD 3 and converted into an electrical signal corresponding to the intensity of the light. The electric signal is amplified through the preamplifier 4 and sent to the signal processing unit at the subsequent stage, and is amplified to a luminance signal as shown in FIG. This luminance signal indicates that the luminance value is larger as the voltage value is larger.
On the other hand, in the window pulse generating means 20, the dividing means divides the screen into two in the vertical direction with reference to the horizon 13 by the above-described screen dividing procedure, and the lower ground area of the divided screen by the selecting means is predetermined. Select as region. Further, the window pulse generating means 20 is given information on the scanning position of the scanning line, and the window pulse generating means 20 is based on the information on the scanning position of the scanning line and the information on the ground area selected by the selecting means. A window pulse shown in FIG. 7B is generated, which is at the H level if the currently scanned position is within the ground area, and at the L level if it is outside the ground area. This window pulse is given to the pulse synthesizing means 21.

The pulse synthesizing unit 21 synthesizes the luminance signal from the amplifier 5 and the window pulse.
In the pulse synthesis means 21, the window pulse is used as a so-called mask signal. That is, when the window pulse is at the L level, it is information when scanning the sky region, so that the luminance signal from the amplifier 5 is prevented from being applied 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, only the luminance signal when the scanning line is scanning the ground area as shown in FIG. 7C is supplied to the averaging circuit 6. The averaging circuit 6 averages the luminance signal and outputs an average luminance value of the ground area. Here, the pulse synthesizing means 21 and the averaging circuit 6 constitute luminance detecting means for detecting the luminance of a predetermined area.
The average luminance value of the ground area is input to one input terminal of the two inputs of the comparator 7. Further, an appropriate average luminance value as a predetermined target luminance is input as a target average luminance value (VT) to the other input terminal of the comparator 7. The comparator 7 compares the brightness levels of the two and outputs the comparison result to the drive circuit 8. Based on the comparison result of the comparator 7, the drive circuit 8 outputs a command signal for reducing the opening area of the iris 2 by a predetermined amount if the average luminance value of the ground area is larger than the target average luminance value (VT). On the contrary, if the average luminance value of the ground area is smaller than the target average luminance 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 at the subsequent stage, and the drive coil 9 changes the opening area of the iris 2 by a predetermined amount based on the drive command.
Here, the comparator 7, the drive circuit 8, and the drive coil 9 constitute an exposure control means.

In the above-described embodiment, the 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. However, based on the difference between the average luminance value of the ground region and the target average luminance value (VT). The iris opening area may be adjusted by an amount that compensates for the difference.
That is, instead of the comparator 7, a means for calculating the difference between two inputs (subtractor, differential amplifier, etc.) is prepared to calculate the difference between the two, and the drive circuit 8 calculates an adjustment amount corresponding to the difference. Alternatively, it may be calculated by map mapping and given to the drive coil 9.
In this case, since the average luminance of the ground area can be corrected to the target average luminance (VT) by one process, the control responsiveness can be improved.

  In the above embodiment, the iris control based on the average luminance value has been described. However, if the average circuit 6 is replaced with a peak value detection circuit, the iris control based on the peak value is performed.

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

  In the first embodiment, the iris control has been described. However, the shutter speed may be controlled based on the luminance of a predetermined area with the iris opening area fixed.

Embodiment 2. FIG.
FIG. 8 is an example of a screen when the front of the car is photographed by the white line recognition device. 14 is an empty road, 15 is a road that is a traveling road, 30 is a white line that is a dividing line that divides the traveling lane, and 31 is a recognized lane area.
In the second embodiment, the ground portion is recognized by the recognition method of the first embodiment, and the white line is further recognized by the ground portion. This white line recognition is performed by, for example, a conventional general method by searching for the outline from the inside and using the white line as the first place where the outline is found. In the second embodiment, the ground area is further subdivided using the left and right white lines recognized in this way as boundaries, and the own lane area is obtained with the inside of the two white lines as the own lane, and this own lane area is selected as the predetermined area. To do.
After the own lane region is selected as the predetermined region, the same control as that in the first embodiment is performed, and negative feedback control is performed so that the luminance of the own lane region matches the target luminance.

If the white line cannot be recognized, the average luminance of the own lane initialization area or the entire ground area or the peak-peak value of the luminance is used as a reference.
Note that the initialization area is an area selected immediately after the power is turned on, and is an own lane area to be recognized when 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 shown above indicate the same or corresponding parts as those described above. Reference numeral 32 denotes a signal processing means for receiving a signal from the preamplifier 4 and processing. Reference numeral 33 denotes a white line recognition processing means as a dividing line detection means for receiving an output from the signal processing means 32 and performing white line recognition. The obtained information is given to the window pulse generating means 20.

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 unit 33 performs white line recognition based on the output from the signal processing unit 32. In step S102, it is determined based on the white line recognition result whether a white line has been correctly detected. If the white line can be correctly recognized, the process proceeds to step S103, the area between the right white line and the left white line is set as the own lane, the own lane is selected as a predetermined area, and the process is terminated. If a white line cannot be detected, the process proceeds to step S104, where a predetermined initialization area is selected as a predetermined area, and the process ends.
After this processing is completed, negative feedback control similar to that in the first embodiment is performed.

  Therefore, according to the second embodiment, since the predetermined area is narrowed to the lane area divided from the ground area into the white line, it is not affected by other than the specific lane. Therefore, an image with more stable luminance can be obtained.

  In the second embodiment, the predetermined area is in the own lane, but the same technique can be applied not only in the own lane but also in any area obtained from the result of white line recognition, such as other lanes. .

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

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

Embodiment 3 FIG.
FIG. 11 is an example of a screen when the front of the vehicle is photographed by the forward vehicle recognition device. 14 is the sky, 15 is the road, 35 is the recognized forward vehicle, and 36 is the peripheral area of the recognized vehicle. Here, the peripheral area 36 corresponds to a predetermined area.
In Embodiment 3, vehicle recognition is first performed within the screen. This is due to, 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 a predetermined area.
Thereafter, the average luminance or peak-peak value of the predetermined area is detected, and negative feedback control is performed in the same manner as in the above-described embodiment so as to obtain the target luminance.

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

Therefore, according to the third embodiment, since the influence other than the recognized peripheral area of the vehicle is not affected, an image with more stable luminance can be obtained.
Further, the third embodiment can be easily applied to control such as front vehicle tracking.

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

Embodiment 4 FIG.
In the fourth embodiment, the screen is divided into a plurality of areas based on luminance, and an area excluding unnecessary areas (for example, empty areas) is selected as a predetermined area.
FIG. 12A shows 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 to this is set as the threshold th.
Σp
th = ──── + δ
n
Here, p represents the luminance of the pixel, n represents the number of pixels, and δ represents a threshold offset value for dividing the region. First, the screen is divided into a plurality of areas according to luminance. As a result, a screen as shown in FIG. Next, when a plurality of areas are classified using the threshold th (luminance> th, luminance <= th), a screen as shown in (b) is obtained.
Finally, when a region where the upper side of each divided region is not in contact with the upper side of the screen or a region whose luminance does not exceed the threshold value is selected, a predetermined region indicated 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 regions based on the luminance of the pixels. In step S132, the threshold value th is set based on the luminance of the screen, and it is determined whether or not the luminance of each region is less than the threshold value th. Here, an area having a luminance less than the threshold th is selected as a predetermined area. In addition, even if the luminance is equal to or higher than the threshold th, an area whose upper side is not in contact with the upper side of the screen is selected as a predetermined area in step S133. That is, in steps S132 and S133, a region in which the luminance is greater than or equal to a predetermined value and the upper side of the region is in contact with the upper side of the screen is determined to be an empty region and is not selected. The area is selected as the predetermined area.
Steps S132 and S133 constitute selection means.
Step S132 constitutes threshold setting means.

It should be noted that the above-described embodiment can be configured by only step S132.
In this case, the screen is divided into two areas depending on whether or not the luminance is less than the threshold th, and an area having the luminance less than the threshold th is selected as the predetermined area.

  Therefore, according to the fourth embodiment, even if the position of the horizon changes on the camera screen due to uphill, downhill or pitching of the vehicle, the sky area is reliably detected and the adverse effect due to the brightness of the sky area is eliminated. Can do.

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

Embodiment 5 FIG.
Embodiment 5 calculates | requires the imaging area which the camera 11 is imaging now, and the position of the present sun, and when it determines with the sun being in an imaging area, area | regions other than the sun and its peripheral area are made into predetermined areas. It is to choose.
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 detection means obtains an imaging area currently captured by the camera 11 from the azimuth, latitude, and longitude of the vehicle, the mounting angle and the angle of view of the camera 11.
On the other hand, the current position of the sun is obtained as follows.
Calendar means constituted by 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 information from the calendar unit.
The determination means determines whether or not the sun is in the imaging area based on the imaging area and the position of the sun. Here, when it is determined that the sun is in the imaging area, an area excluding the sun and the surrounding area is selected as the predetermined area.

  Thereby, the influence by the sun which has excessive brightness | luminance can be eliminated.

In this embodiment, when the sun is in the imaging region, the adverse effect is mitigated by excluding the surrounding region. However, in such a case, the control may be stopped.
That is, in this case, a threshold value is provided as a criterion for determining whether or not the sun is in the screen, and means for stopping the control when the average luminance value or peak-peak value of the screen exceeds this threshold value is provided. That's fine.
According to this, a structure can be simplified rather than the above-mentioned embodiment.

  In the fifth embodiment, the iris control is performed based on the brightness of the region other than the sun and the surrounding region. However, the iris opening area may be fixed and the shutter speed may be controlled instead.

Embodiment 6 FIG.
The sixth embodiment does not divide the screen and select a predetermined area as in the above-described embodiment, but tries to eliminate the influence of sky brightness by other methods.
FIG. 14 is an external view showing the configuration of the sixth embodiment. Reference numeral 10 denotes a vehicle, 11 denotes an in-vehicle camera, and 40 denotes a light meter that is a light amount detection means. The photometer 40 is mounted upward so that the brightness of the sky can be taken.
The detection result of the light meter 40 is used to correct the iris adjustment amount.
FIG. 15 is a block diagram showing the configuration of the sixth embodiment. In the figure, the same reference numerals as those shown above denote the same or corresponding parts. Reference numeral 41 denotes a drive circuit.
That is, the output of the light meter 40 is given to the drive circuit 41. The drive circuit 41 has correction means for reducing the opening area of the iris 2 as the brightness of the sky is brighter based on the detection output of the light meter 40 and increasing the opening area of the iris 2 as the sky brightness becomes darker. Based on the output of the correction means, a drive command is generated to drive the drive coil 9. As a result, the opening area of the iris 2 changes according to the detection output of the light 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 opening area of the iris 2 is changed according to the value of the light meter.

Thereby, for example, it is possible to prevent the iris from moving in an unstable manner such that the average brightness of the screen increases due to a white pattern drawn on a road such as a pedestrian crossing, and the iris operates.
The target luminance may be a peak-peak value instead of the average luminance.

  In the sixth embodiment, the iris control is performed based on the output of the light meter. However, the iris opening area may be fixed, and the shutter speed may be controlled instead.

Embodiment 7 FIG.
In the seventh embodiment, the brightness of the sky is estimated by detecting the weather, and the influence of the brightness of the sky is eliminated.
That is, when trying to project a general road at an appropriate luminance level, the iris state does not change much in the daytime when it is fine or cloudy. However, the amount of iris adjustment is clearly different in the three situations of daytime sunny weather, daytime rainy weather, and nighttime. This is because the brightness of the sky is completely different in the above three situations.
In the seventh embodiment, therefore, the weather is detected to determine which one of the three situations, and the iris adjustment amount corresponding to each of the three situations is set.

FIG. 17 is a block diagram showing the configuration of the seventh embodiment. In the figure, the same reference numerals as those shown above denote the same or corresponding parts. Reference numeral 42 denotes an adjusting means which is provided with on / off information of a wiper switch and a headlight switch.
The operation of the seventh embodiment will be described using 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 headlight is on, it is estimated that it is nighttime, so the process proceeds to step S182 and the nighttime mode is selected. If it is determined in step S181 that the headlight is off, it can be estimated that it is daytime. Therefore, the process proceeds to step S183 to determine whether the weather is clear or not depending on whether the wiper is on. If the wiper is on, the process proceeds to step S184 to select the daytime rainy mode, and if the wiper is off, the process proceeds to step S185 to select the daytime clear sky mode.
Note that fixed iris adjustment amounts that are appropriate for the three modes are prepared. After one of the three modes is selected, the process proceeds to step S186, and a command corresponding to the selected iris adjustment amount is output to the drive circuit 8. Based on this command, the drive circuit 8 drives the drive coil 9 to drive the iris.

  Therefore, according to the seventh embodiment, the iris is linked to the headlight switch and the wiper switch, and the iris is fixed at a constant value in response to the night time and the rainy weather. Appropriate road images can be obtained even in three situations at night and at night.

  In the seventh embodiment, the headlight switch and the wiper switch constitute weather detection means.

  In the above-described embodiment, the headlight switch and the wiper switch are used as the weather detection means. For example, the value of the hygrometer is provided with a hygrometer that detects the average luminance of the screen and thereby determines whether it is day or night. It may be determined whether the weather is fine or rainy, and what kind of detection means is used is free.

  In the seventh embodiment, the iris control is performed according to the three situations. However, the iris opening area is fixed, and instead the shutter speed according to the three situations is prepared and the shutter speed is controlled. Also good.

Embodiment 8 FIG.
The eighth embodiment provides an exposure control apparatus capable of detecting a failure.
That is, in this type of apparatus, various controls (for example, white line recognition, forward vehicle tracking, surrounding monitoring system, etc.) are performed based on the screen shot 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 vehicle is in a driving state in which various controls are performed based on the screen shot by the camera. If it is determined that the operation is not required, that is, a predetermined operation state, the normal iris control is stopped and a failure diagnosis operation is performed.

FIG. 19 is a flowchart showing the operation of the eighth embodiment.
First, in steps S201 to 203, it is determined whether or not 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 equal to or less than a predetermined value, it is determined that the vehicle is in a predetermined driving state, and the process proceeds to step S204 and subsequent steps. On the other hand, if it is determined that it is not in the predetermined operation state, the process is terminated as it is, and normal control is performed. Note that the detection means or vehicle speed sensor for detecting the state of the side brake or gear constitutes a driving state detection means, and steps S201 to S203 constitute a determination means.

  When it is determined that the vehicle is in the predetermined operating state, the process proceeds to step S204, and the average luminance of the screen at this time is detected and stored as the first luminance V1. After the storage is completed, the process proceeds to step S205, and a command to fully open the iris 2 is output. In step S206, the system waits for a predetermined time estimated that the iris is fully opened, and detects the average luminance after opening the iris in step S207 as the second luminance V2. In step S208, the first luminance V1 and the second luminance V2 are compared. If the second luminance V2 is greater than the first luminance V1, it is determined that the iris opening area has increased as instructed. The process proceeds to S209. In step S209, on the contrary, a command for fully closing the iris is output, and in step S210, the process waits for a predetermined time estimated that the iris is fully opened from the fully open state. When the predetermined time has elapsed, the process proceeds to step S211, and the brightness after the iris is closed is detected as the third brightness V3. In step S212, the first luminance V1 and the third luminance V3 are compared. If the first luminance V1 is larger, it is determined that the iris is closed as instructed. In step S213, it is determined that the apparatus is normal. To do. At this time, it may be displayed or notified to the driver that it is normal.

  On the other hand, if it is determined NO in step S208 or step S212, it is determined that there is a failure in step S214, and a failure display or warning is given in the subsequent step S215.

  In the eighth embodiment, steps S205 and S209 constitute exposure amount changing means, steps S204, S207 and S211 constitute luminance detecting means, and steps S208 and S212 constitute failure determining means.

  Therefore, according to the eighth embodiment, when the normal operation of the iris cannot be confirmed, the driver is notified of the iris abnormal 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.

  In addition, since the failure self-diagnosis operation is performed in an operating state that does not require normal iris control or shutter speed control, 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 similarly detected.
In that case, the iris fully open / close command may be replaced with the shutter speed maximum / minimum command.

Embodiment 9 FIG.
In the first to eighth embodiments described above, the iris control has been described. In the ninth embodiment, an example in which the first embodiment is applied to the shutter speed control will be described.
In this case, the iris opening area 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 configuration 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 described above indicate the same or corresponding parts. Reference numeral 50 denotes 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. The operation is the same as that of the first embodiment until the comparison means 7 compares the average luminance obtained by the calculation with the target average luminance (VT).
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 during the other periods. That is, the shutter is opened in synchronization with the rising edge of the pulse signal and closed in synchronization with the falling edge.
The timing pulse generator 50 receives the comparison result from the comparator 7 and sets the shutter speed (exposure time). If the target average brightness is larger, the screen is darker, so the shutter speed is decreased by a predetermined amount to brighten the screen. This is achieved by extending the period during which the pulse signal is at the H level by a predetermined time.

In the next sampling, if the target average luminance is still larger than the average luminance, the timing pulse generator 50 again decreases the shutter speed by a predetermined amount.
In the next sampling, if the target average brightness is smaller than the average brightness, 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 the H level by a predetermined time.

  As described above, the brightness of the screen can be controlled by controlling the shutter speed regardless of the iris.

  In the ninth embodiment, the target average brightness is compared with the average brightness, 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. May be. 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. However, not only the first embodiment but also all the embodiments can be easily applied to the shutter speed control.

It is an external view which shows the state which attached the camera to the vehicle. It is a figure which shows the screen image | photographed with a camera. It is a perspective view which shows the angle of view of a camera. It is a side view which shows the attachment angle of a camera. It is a figure which shows the case where a coordinate is attached | subjected to the screen image | photographed with a camera. 1 is a block diagram illustrating a configuration of a first embodiment. 3 is a time chart showing the operation of the first embodiment. It is an example of the screen when the front of the car is taken with the white line recognition device. 6 is a block diagram illustrating a configuration of a second embodiment. FIG. 10 is a flowchart showing the operation of the second embodiment. It is an example of the screen when the front of the vehicle is photographed by the forward vehicle recognition device. It is an example of the screen image | photographed with the camera. 10 is a flowchart showing the operation of the fourth embodiment. FIG. 16 is an external view showing a configuration of a sixth embodiment. FIG. 10 is a block diagram illustrating a configuration of a sixth embodiment. 18 is a flowchart showing the operation of the sixth embodiment. FIG. 10 is a block diagram illustrating a configuration of a seventh embodiment. 18 is a flowchart showing the operation of the seventh embodiment. 20 is a flowchart showing the operation of the eighth embodiment. FIG. 20 is a block diagram showing the configuration of the ninth embodiment. It is a block diagram which shows a conventional apparatus.

Explanation of symbols

1: lens, 2: iris, 3: CCD, 4: preamplifier, 5: amplifier, 6: average 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 meter, 41: Drive circuit, 42: Adjustment means, 50: Timing pulse generation means

Claims (2)

A lens that collects the light;
Imaging means for outputting a signal according to the luminance of light from the lens;
Exposure amount adjusting means for adjusting the exposure amount of the imaging means;
Brightness detection means for detecting the brightness of the screen of the imaging means;
Driving state detection means for detecting the driving state of the vehicle;
Determination means for determining whether or not a predetermined operation state based on the detection output of the operation state detection means;
An exposure amount changing means for adjusting the exposure amount adjusting means to change the exposure amount of the imaging means in the increasing or decreasing direction when it is determined that the determining means is in the predetermined operating state;
An exposure control apparatus for a vehicular camera, comprising: failure determination means for determining failure based on whether or not the brightness of the screen of the imaging means has increased or decreased in accordance with an increase or decrease in the exposure amount. 2. The vehicle according to claim 1, wherein the exposure amount adjusting means includes an iris for adjusting an intensity of light incident on the imaging means, and a shutter for adjusting an exposure time of light incident on the imaging means. Camera exposure control device.

Images