JP2007022454A - Camera system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust photographing conditions of a camera according to photographing environment such as luminosity or the like of a photographing area by a simple constitution and to display the properly photographed image. <P>SOLUTION: In the camera system 1, a rear side of the vehicle is photographed by the on-vehicle rear camera 10 while switching a back mode and a rear side monitoring mode and the image is displayed on an on-vehicle display 40. The camera system 1 is provided with a mode determination part 23 for determining whether the present photographing state is the back mode or the rear side monitoring mode based on a predetermined condition; a night determination part 24 for determining whether or not the present time is night based on a predetermined condition; light measurement control parts (21, 14, 16) for light-measuring a relatively upper area in the photographing area than a light-measurement area at the back mode when the photographing state is the rear side monitoring mode at night; and a photographing condition adjustment part 17 for adjusting the photographing condition by the rear camera 10 based on the light-measurement result. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a camera system. More specifically, the present invention relates to a first mode for imaging the rear and side of a vehicle when the vehicle is moving backward, and a second mode for imaging the rear and side of the vehicle when the vehicle is moving forward. And a camera system that captures the rear and side of the vehicle with a camera installed in the vehicle and displays the captured image on a display device installed in the vehicle.

Conventionally, in order to smoothly put a vehicle in a garage or the like, when a vehicle moves backward, a camera mounted on the vehicle captures an area behind the vehicle and displays the captured image on a display device mounted on the vehicle. The system is known. In this system, in order to image a generally dark area behind the vehicle, the sensitivity of the camera for imaging is mostly set high.
Japanese Patent Laid-Open No. 9-9136

  However, when the above-mentioned camera mounted on the vehicle is also used for other purposes, most conventional systems cannot adjust the sensitivity of the camera according to the imaging environment such as the brightness of the area to be imaged. . For this reason, for example, when imaging the rear and side of a vehicle while traveling, even if the subsequent vehicle is imaged with a camera with high sensitivity, a so-called blooming phenomenon occurs due to the headlight of the subsequent vehicle. It was difficult to display an image with appropriate brightness.

  However, a technique itself for adjusting the sensitivity of the camera in accordance with the imaging environment is proposed in, for example, Patent Document 1 described above. However, in the technique of Patent Document 1, it is necessary to provide a complicated device for performing automatic control such as auto white balance control and automatic exposure control, a special device for environment determination, and the like. Therefore, there has been a demand for a technique for adjusting the imaging condition of the camera in accordance with the imaging environment such as the brightness of the imaging area with a simple configuration without requiring such complicated equipment and special equipment.

  The present invention has been made in order to solve the above-described problems. With a simple configuration, an image is properly captured after adjusting the imaging conditions of the camera according to the imaging environment such as the brightness of the imaging area. An object is to provide a camera system capable of displaying an image.

  In order to achieve the above object, a camera system according to the present invention includes a first mode in which images of the rear and sides of a vehicle are taken during the backward movement of the vehicle, and a first mode in which images of the rear and sides of the vehicle are taken during forward movement of the vehicle. A camera system that captures the rear and side of a vehicle with a camera installed in the vehicle while switching between the two modes, and displays the captured image on a display device installed in the vehicle, based on a predetermined condition A mode determination unit that determines whether the current imaging state is the first mode or the second mode, a night determination unit that determines whether the current time is night based on a predetermined condition, When the mode determination unit determines that the imaging state is the second mode and the night determination unit determines that the current time is night, the imaging area of the camera is larger than the photometric area when the imaging state is the first mode. A metering control unit for metering a definitive relatively upper region, on the basis of the photometry result of the photometry control unit, characterized in that an imaging condition adjusting unit that adjusts an imaging condition by the camera.

  That is, the mode determination unit determines whether the current imaging state is the first mode or the second mode based on a predetermined condition. Here, for example, it may be determined whether the current imaging state is the first mode or the second mode based on the speed of the vehicle. That is, when the vehicle speed is equal to or higher than a predetermined reference value (40 km / h as an example), the imaging state is determined as the second mode, and when the vehicle speed is less than the reference value (in the case of a negative speed, that is, The imaging state may be determined as the first mode, including the case of the backward movement. Here, when a signal is output from the gear R (reverse), it may be determined that the reverse operation is being performed, and the imaging state may be determined as the first mode. In addition, the imaging state may be determined to be the second mode also when the steering operation of the vehicle is performed or when it is determined that the vehicle is traveling on the highway by the navigation system.

  The night determination unit determines whether or not the current time is night based on a predetermined condition. Here, for example, it may be determined whether or not the current time is at night according to the time of the built-in clock, or the average value of brightness (brightness) of the entire photometry area in the case of photometry is obtained and the average value is predetermined. You may determine with the present time being nighttime when it is below a reference value. The night determination unit may determine that the current time is night when a signal is output from a light control switch that is operated during night illumination.

  As a feature of the present invention, when the mode determination unit determines that the imaging state is the second mode and the night determination unit determines that the current time is night, the photometry control unit determines that the imaging state is the first mode. The area relatively above the image capturing area of the camera is measured with respect to the current photometric area, and the image capturing condition adjusting unit adjusts the image capturing condition of the camera based on the photometric result.

  At night, when the imaging state is in the second mode, the following vehicle often enters a relatively upper area in the imaging area of the camera. Therefore, the upper area is photometrically measured by the camera based on the photometric result. By adjusting the imaging conditions, the blooming phenomenon can be prevented, and the imaging conditions of the camera can be adjusted in accordance with the imaging environment such as the brightness of the imaging area, and then properly captured images can be displayed on the display device. And the visibility by the driver can be improved. Further, the present invention is based on the essence that the photometry area is narrowed down to the area relatively higher in the imaging area of the camera than the photometry area in the first mode. The imaging condition can be adjusted according to the imaging environment with a simple configuration that is not necessary.

  By the way, the above-mentioned photometry control unit determines whether or not there is one or more high-luminance areas whose luminance is higher than a predetermined threshold in the upper area in photometry of the upper area. In the upper area, it is desirable that the photometry is performed by limiting the photometry area to a predetermined size including the high luminance area. With this configuration, it is possible to perform photometry in a photometric area of a predetermined size including a high luminance area corresponding to the position of the following vehicle at night, and adjust the imaging conditions of the camera based on a more appropriate photometric result be able to.

  Further, the camera system further includes a steering angle detection unit that detects the steering angle of the steering wheel of the vehicle, and the photometry control unit changes a region to be measured in accordance with the steering angle of the steering wheel detected by the steering angle detection unit, It is desirable that the area after the change is metered. With such a configuration, it is possible to perform photometry on an appropriate area corresponding to the steering angle of the steering wheel as a photometric object, and it is possible to adjust the imaging condition of the camera based on a more appropriate photometric result.

  Further, the camera system preferably further includes a display control unit that displays a symbol simulating the white line of the own lane on a captured image so as to be superimposed on the captured image. With this configuration, it is possible to easily recognize the lane in which the following vehicle is traveling at night.

  According to the present invention, when the imaging state is the second mode at night, the following vehicle often enters a relatively upper area in the imaging area of the camera. Adjusting the imaging conditions of the camera based on the result prevents blooming phenomenon and displays the properly captured image after adjusting the imaging conditions of the camera according to the imaging environment such as the brightness of the imaging area It can be displayed on the device, and the visibility by the driver can be improved. Further, the present invention is based on the essence that the photometry area is narrowed down to the area relatively higher in the imaging area of the camera than the photometry area in the first mode. The imaging condition can be adjusted according to the imaging environment with a simple configuration that is not necessary.

  Hereinafter, various embodiments of the camera system according to the present invention will be described in order. The camera system according to the present invention includes a camera that captures the rear and side of the vehicle (hereinafter referred to as “rear camera”), and a first mode for capturing the rear and side of the vehicle when the vehicle is moving backward ( (Hereinafter referred to as “back mode”) and a second mode (hereinafter referred to as “rear side monitoring mode”) for imaging the rear and side of the vehicle (hereinafter referred to as “rear side of the vehicle”) during forward movement of the vehicle; , The rear and side of the vehicle are imaged by the rear camera, and the captured images are displayed on a display device installed in the vehicle.

[First Embodiment]
In the first embodiment, in the rear side monitoring mode at night, photometry is performed on a region above the imaging area relative to the back mode, and the imaging conditions of the rear camera are adjusted based on the photometry results. An embodiment will be described.

[Camera system configuration]
First, the configuration of the camera system will be described with reference to FIGS. As shown in FIG. 2, the camera system 1 includes a rear camera 10 for imaging the rear and side of the vehicle 2 (see FIG. 1), a control unit 20 that controls the operation of the camera system 1, A front camera 30 for imaging the front, a display 40 as a display device for displaying the captured image, a vehicle speed detection unit 50 for detecting the speed (vehicle speed) of the vehicle 2, a gear R (reverse) 55, A steering angle detection unit 60 that detects the steering angle of the steering wheel of the vehicle 2 and a light control switch 65 that is operated during nighttime illumination are configured.

  The rear camera 10 is composed of a wide viewing angle camera in which the viewing angle θ shown in FIG. 1 is set to a large angle, and can capture a wide range of areas on the rear and side of the vehicle 2. The rear camera 10 is installed, for example, at the rearmost central portion of the vehicle 2 shown in FIG. As shown in FIG. 2, the rear camera 10 includes an image sensor 11, an AGC (Automatic Gain Control) 12, an AD converter 13, a DSP (Digital Signal Processor) 14, an encoder 15, a photometry unit 16, and imaging conditions. An adjustment unit 17 and a control signal reception unit 18 are included.

  Although details will be described later, when the control signal receiving unit 18 receives a control signal related to the operation of the photometry unit 16 from the camera control unit 21, the control signal receiving unit 18 transfers the control signal to the DSP 14. The DSP 14 that has received the control signal controls the photometric operation by the photometric unit 16 such as narrowing the photometric area based on the control signal. The photometric result obtained by the photometric operation is transferred to the imaging condition adjusting unit 17, and the imaging condition adjusting unit 17 adjusts the imaging condition of the rear camera 10 according to the photometric result. Specifically, exposure control for the image sensor 11 and gain control for the AGC 12 are performed. After adjusting the imaging conditions, the image signal captured by the image sensor 11 is input as image data to the DSP 14 via the AGC 12 and the AD converter 13. The DSP 14 may perform predetermined distortion correction on the image data. However, in the present embodiment, an example in which distortion correction is not performed will be described. Thereafter, the image data is encoded by the encoder 15, and the encoded image data is output to the display control unit 22 of the control unit 20.

  The control unit 20 includes a camera control unit 21 that controls the overall operation of the camera system 1, a display control unit 22 that includes a decoder (not shown) and controls image display processing on the display 40, and predetermined conditions (for example, vehicle speed). Based on the vehicle speed detected by the detection unit 50), a mode determination unit 23 for determining whether the current imaging state is the rear side monitoring mode or the back mode, and whether the current time is night based on a predetermined condition And a night determination unit 24 that determines whether or not.

  In addition, a detection signal (a signal indicating the steering angle of the steering wheel) by the steering angle detection unit 60 is input to the camera control unit 21, and the camera control unit 21 has a function of changing the photometric area according to the steering angle of the steering wheel. . Details of this function will be described in the third embodiment. The display control unit 22 has a function of superimposing a symbol simulating the white line of the own lane on the captured image and displaying the symbol on the display 40. Details of this function will be described after the third embodiment, but the display control unit 22 changes the display position of the symbol according to the rudder angle detected by the rudder angle detection unit 60 or picks up an image with the front camera 30. The image data is received, the position of the white line behind the own lane and the interval are obtained from the image data, and the symbol is displayed.

  The mode determination unit according to the present invention is the mode determination unit 23, the night determination unit is the night determination unit 24, the imaging condition adjustment unit is the imaging condition adjustment unit 17, the steering angle detection unit is the steering angle detection unit 60, The display control unit corresponds to the display control unit 22. The photometry control unit corresponds to a configuration including the camera control unit 21, the DSP 14, and the photometry unit 16. Moreover, in 1st Embodiment, the front camera 30 and the steering angle detection part 60 of FIG. 2 are not an essential component requirement.

[Operation of First Embodiment]
FIG. 3 shows an image of the rear side of the vehicle 2 captured by the rear camera 10. As shown in the figure, the rear end portion of the host vehicle 2 is shown in the lowermost part of the image, and the white line 70 of the host lane is shown thereabove. A horizontal line 71 appears in the vicinity of the upper end of the image. In this embodiment, since the distortion correction is not performed on the image captured by the rear camera 10 that is a wide viewing angle camera, the white line 70 and the horizontal line 71 are curved. Here, of course, distortion correction may be performed. In this case, the white line 70 and the horizontal line 71 are displayed as straight lines, and are easy to see for the driver.

  Prior to imaging with the rear camera 10, photometry is performed by the photometry unit 16 in order to adjust imaging conditions. In the back mode, as shown in FIG. Photometry is performed on an area R1 excluding the lower part and the uppermost part where the sky is reflected.

  On the other hand, in the case of the rear side monitoring mode, it is necessary to fully consider the influence of the headlight of the following vehicle, particularly at night, so photometry is performed on the upper region R2 including the following vehicle 72 shown in FIG. I do.

  A processing procedure for performing photometry, imaging, and image display while switching the target area for photometry will be described with reference to FIG. First, in S01, the mode determination unit 23 determines whether the current imaging state is the rear side monitoring mode or the back mode depending on whether the vehicle speed obtained from the vehicle speed detection unit 50 is equal to or higher than a predetermined reference value. Determine. For example, when the vehicle speed is equal to or higher than a predetermined reference value (40 km / h as an example), it is determined that the imaging state is the rear side monitoring mode, and when the vehicle speed is less than the predetermined reference value (of course, in the case of a negative speed, That is, it may be determined that the imaging state is the back mode (including the case of the backward movement). Here, when the signal is output from the gear R (reverse) 55, it may be determined that the reverse operation is being performed, and the imaging state may be determined as the first mode. In addition, when the steering operation of the vehicle is performed based on the steering angle detected by the steering angle detection unit 60 or when it is determined that the vehicle is traveling on the highway by the navigation system, the imaging state is in the rear side monitoring mode. You may determine that. When it is determined in S01 that the current imaging state is the back mode, the process proceeds to S02, and the operation in the previous back mode is performed.

  If it is determined in S01 that the current imaging state is the rear side monitoring mode, the process proceeds to S03, and the night determination unit 24 determines whether the current time is night based on a predetermined condition. For example, it may be determined whether the present time is night (for example, the current time is after 6 pm or before 6 am) according to the time of a clock built in the night determination unit 24. In addition, the photometry result of the photometry unit 16 is fed back to the control unit 20, and the night determination unit 24 in the control unit 20 obtains an average luminance (brightness) value of the entire photometry area and the average value is equal to or less than a predetermined reference value. In this case, it may be determined that the current time is at night. The night determination unit 24 may determine that the current time is night when a signal is output from the light control switch 65 that is operated during night illumination. If it is determined in S03 that the current time is not nighttime, the process proceeds to S04 to perform a predetermined operation in the rear side monitoring mode in the daytime.

  If it is determined in S03 that the current time is night, the process proceeds to S05, and the camera control unit 21 performs photometry in the rear side monitoring mode at night, that is, in the upper region R2 shown in FIG. A control signal instructing to do so is transmitted to the rear camera 10. The control signal is transferred to the DSP 14 via the control signal receiving unit 18, and the DSP 14 controls the photometry unit 16 to perform photometry on the upper region R2 in FIG. As a result, photometry is performed on the upper region R2 where the headlight of the following vehicle is likely to be captured at night. The photometric result obtained by the photometric operation is transferred to the imaging condition adjusting unit 17.

  In next S06, the imaging condition adjustment unit 17 adjusts the imaging condition of the rear camera 10 according to the photometric result. Specifically, exposure control for the image sensor 11 and gain control for the AGC 12 are performed. In the present embodiment, since the photometry is performed for the upper region R2 in which the possibility of the headlight of the following vehicle being captured at night in S05, the photometric value generally increases. Therefore, in S06, the imaging condition is adjusted so as to reduce the sensitivity of the rear camera 10.

  In the next S07, the rear side image captured by the rear camera 10 in which the imaging conditions are adjusted is displayed on the display 40. Specifically, after adjusting the imaging conditions as described above, the image signal captured by the image sensor 11 is input as image data to the DSP 14 via the AGC 12 and the AD converter 13. Then, the image data is encoded by the encoder 15, and the encoded image data is output to the display control unit 22 of the control unit 20. The display control unit 22 displays the rear side image on the display 40 after decoding the encoded image data by the built-in decoder. The processing procedure of FIG. 6 described above is repeatedly executed at predetermined intervals while the camera system 1 is powered on.

  According to the first embodiment as described above, photometry is performed on the upper region R2 in which the headlight of the following vehicle is likely to be captured at night, and the imaging condition of the rear camera 10 is adjusted according to the photometry result. Therefore, the blooming phenomenon can be prevented, the image capturing condition of the camera can be adjusted according to the image capturing environment such as the brightness of the image capturing area, and the properly captured image can be displayed on the display device. Can be improved. In addition, since the photometric area is narrowed down to the upper area R2 (an area relatively higher than that in the back mode), an imaging condition corresponding to the imaging environment can be obtained with a simple configuration without requiring complicated equipment or special equipment. Can be adjusted.

[Second Embodiment]
In the second embodiment, in the case of the rear side monitoring mode at night, a high brightness area in the imaging area is detected, and the photometry is performed by focusing on a photometry area of a predetermined size including the high brightness area. An embodiment for adjusting the imaging conditions of the rear camera will be described.

  Since the configuration of the camera system 1 in the second embodiment is the same as the configuration in FIGS. 1 and 2 described above, a duplicate description is omitted. In the second embodiment, the front camera 30 and the steering angle detection unit 60 in FIG. 2 are not essential constituent requirements.

[Operation of Second Embodiment]
The operation of the second embodiment will be described based on FIG. As in the first embodiment, in S11, the mode determination unit 23 determines that the current imaging state is the rear side monitoring mode depending on whether the vehicle speed obtained from the vehicle speed detection unit 50 is equal to or higher than a predetermined reference value. Or back mode. If it is determined that the current imaging state is the back mode, an operation in the previous back mode is performed (S12).

  If it is determined in S11 that the current imaging state is the rear side monitoring mode, the process proceeds to S13, and the night determination unit 24 determines whether the current time is night based on a predetermined condition. For example, it may be determined whether or not the present time is night (for example, the time is after 6 pm or before 6 am) according to the time of a clock incorporated in the night determination unit 24. If it is determined that the current time is not nighttime, a predetermined operation in the rear side monitoring mode in the daytime is performed (S14).

  If it is determined in S13 that the current time is nighttime, the process proceeds to S15, and photometry is performed on the upper region R2 in FIG. 5, and one or more high-luminance regions (luminances) in the region R2 are determined from the photometry results. It is determined whether or not there is a region whose value is equal to or greater than a predetermined threshold value. This determination can be performed as follows, for example. That is, when it is determined in S13 that the current time is night, the camera control unit 21 that has received the determination signal from the night determination unit 24 performs photometry on the region R2 in FIG. A control signal is transmitted to the DSP 14 for instructing whether or not one or more high-luminance areas exist. Upon receiving such a control signal, the DSP 14 causes the photometry unit 16 to perform photometry on the region R2 in FIG. 5, and determines whether one or more high-luminance regions exist in the region R2 based on the photometry result. Can do.

  When it is determined in S15 that the high brightness area does not exist, the DSP 14 controls the photometry unit 16 to perform photometry on the upper area R2 in FIG. 5 as in the first embodiment. The photometric result obtained by the photometric operation is transferred to the imaging condition adjusting unit 17.

  On the other hand, when it is determined in S15 that the high brightness area exists, the DSP 14 controls the photometry unit 16 to perform the photometry while narrowing down to a predetermined photometry area including the high brightness area. For example, when it is determined that the high brightness area 73 illustrated in FIG. 7 exists, the photometry is performed by focusing on the photometry area R3 having a predetermined size including the high brightness area 73. That is, photometry is performed by focusing on the photometry region R3 including the high luminance region 73 in which the headlight of the following vehicle is captured at night. The photometric result obtained by the photometric operation is transferred to the imaging condition adjusting unit 17.

  FIG. 7 shows an example in which only one high-luminance area 73 exists. However, when there are a plurality of high-luminance areas 73, a photometric area having a predetermined size including the high-luminance areas 73 is a high-luminance area. It is set for each 73, and photometry is performed with respect to the plurality of photometry areas.

  In next S18, the imaging condition adjustment unit 17 adjusts the imaging condition of the rear camera 10 according to the photometric result. Specifically, exposure control for the image sensor 11 and gain control for the AGC 12 are performed. In the next S19, the rear side image captured by the rear camera 10 in which the imaging conditions are adjusted is displayed on the display 40. Specifically, after adjusting the imaging conditions as described above, the image signal captured by the image sensor 11 is input as image data to the DSP 14 via the AGC 12 and the AD converter 13. Then, the image data is encoded by the encoder 15, and the encoded image data is output to the display control unit 22 of the control unit 20. The display control unit 22 displays the rear side image on the display 40 after decoding the encoded image data by the built-in decoder. The processing procedure of FIG. 8 described above is repeatedly executed at predetermined intervals while the camera system 1 is powered on.

  According to the second embodiment as described above, photometry can be performed by focusing on the photometry area R3 including the high brightness area 73 in which the headlight of the following vehicle is captured at night, and the camera is based on a more appropriate photometry result. The imaging conditions can be adjusted.

[Third Embodiment]
In the third embodiment, in the rear side monitoring mode at night, the photometric area is changed according to the steering angle of the steering wheel (for example, changed to just behind the same lane), and the photometric area after the change is metered. An embodiment in which the imaging conditions of the rear camera are adjusted based on the photometric result will be described.

  Since the configuration of the camera system 1 in the third embodiment is the same as the configuration in FIGS. 1 and 2 described above, a duplicate description is omitted. In the third embodiment, the front camera 30 in FIG. 2 is not an essential component.

[Operation of Third Embodiment]
The operation of the third embodiment will be described based on FIG. As in the first embodiment, in S21, the mode determination unit 23 determines that the current imaging state is the rear side monitoring mode depending on whether or not the vehicle speed obtained from the vehicle speed detection unit 50 is equal to or higher than a predetermined reference value. Or back mode. If it is determined that the current imaging state is the back mode, the operation in the previous back mode is performed (S22).

  When it is determined in S21 that the current imaging state is the rear side monitoring mode, the process proceeds to S23, and the night determination unit 24 determines whether the current time is night based on a predetermined condition. For example, it may be determined whether or not the present time is night (for example, the time is after 6 pm or before 6 am) according to the time of a clock incorporated in the night determination unit 24. If it is determined that the current time is not nighttime, a predetermined operation in the rear side monitoring mode in the daytime is performed (S24).

  If it is determined in S23 that the current time is nighttime, the process proceeds to S25, and the camera control unit 21 determines whether or not the steering wheel is being operated at that time (ie, the steering wheel is turned to the right or left). The determination is made based on the output signal (detected rudder angle) of the rudder angle detector 60. In this determination, for example, when the absolute value of the steering angle to the right or left is greater than or equal to a predetermined reference value, it is determined that the steering operation is being performed, and when the absolute value of the steering angle is less than the predetermined reference value, the steering operation is not being performed. Can be determined.

  If it is determined in S25 that the steering wheel is not being operated, in S26, the camera control unit 21 instructs to perform light metering on a region (for example, the region R3 in FIG. 7) immediately behind the host vehicle (back of the same lane). A signal is transmitted to the rear camera 10. Such a control signal is transferred to the DSP 14 via the control signal receiving unit 18, and the DSP 14 controls the photometry unit 16 to perform photometry on the area immediately behind the host vehicle (the rear of the same lane). The reason for performing light metering only on the area just behind the host vehicle (behind the same lane) is that the headlight has directivity, so the same lane is used rather than the headlight of the following vehicle traveling in the adjacent lane. This is because the headlight of the following vehicle that is running has a greater influence on the photometric result and is likely to cause blooming. That is, when the steering operation is not being performed, by performing photometry on only the area immediately behind the host vehicle (back of the same lane), the imaging conditions of the camera can be adjusted based on a more appropriate photometry result. The photometric result obtained by the photometric operation is transferred to the imaging condition adjusting unit 17.

  On the other hand, when it is determined in S25 that the steering wheel is being operated, the camera control unit 21 changes the photometric target region according to the steering angle detected by the steering angle detection unit 60 and targets the changed region. A control signal instructing to perform photometry is transmitted to the rear camera 10. Such a control signal is transferred to the DSP 14 via the control signal receiver 18. Based on the control signal, the DSP 14 changes the photometric target region according to the steering angle of the steering wheel detected by the steering angle detection unit 60 (S27), and performs photometry on the changed region by the photometric unit 16 (S27). S28). For example, the photometric area is changed from the area R3 in FIG. 7 to the area R4 in FIG. 9, and photometry is performed on the changed area R4. As a result, even if the steering wheel is being operated, photometry is performed on the region R4 where the headlight of the following vehicle 74 (see FIG. 9) in the same lane is likely to be captured at night. The photometric result obtained by the photometric operation is transferred to the imaging condition adjusting unit 17.

  In next S29, the imaging condition adjustment unit 17 adjusts the imaging condition of the rear camera 10 according to the photometric result. Specifically, exposure control for the image sensor 11 and gain control for the AGC 12 are performed. In the next S30, the rear side image captured by the rear camera 10 in which the imaging conditions are adjusted is displayed on the display 40. Specifically, after adjusting the imaging conditions as described above, the image signal captured by the image sensor 11 is input as image data to the DSP 14 via the AGC 12 and the AD converter 13. Then, the image data is encoded by the encoder 15, and the encoded image data is output to the display control unit 22 of the control unit 20. The display control unit 22 displays the rear side image on the display 40 after decoding the encoded image data by the built-in decoder. The processing procedure of FIG. 10 described above is repeatedly executed at predetermined intervals while the camera system 1 is powered on.

  According to the third embodiment as described above, it is possible to perform photometry on an appropriate area corresponding to the steering angle of the steering wheel as a photometric object, and to adjust the imaging condition of the camera based on a more appropriate photometric result. .

  In addition, in the case of the rear side monitoring mode at night by combining the points of the second and third embodiments described above, a high brightness area in the imaging area is detected and a photometric area of a predetermined size including the high brightness area is detected. When the steering wheel is operated while traveling while performing the metering while narrowing down, the metering area may be changed according to the steering angle of the steering wheel, and the metering area after the change may be measured. In such a case, the imaging conditions of the camera can be adjusted based on a more appropriate photometric result.

  In each of the above-described embodiments, an example in which the photometry area and the imaging condition of the camera are automatically changed has been described. However, the driver may be configured to be able to change the setting manually from the user interface. The change and manual setting change may coexist.

  In each of the above embodiments, the camera control unit 21 in the control unit 20 mainly controls the operation of the camera system 1. However, instead of the camera control unit 21, the DSP 14 in the rear camera 10 has a vehicle speed. You may comprise so that operation | movement of the camera system 1 may be controlled centrally based on the detection result from the detection part 50 or the steering angle detection part 60. FIG.

  Further, for signal transmission between the respective components in FIG. 2, for example, signal transmission between the rear camera 10 and the control unit 20, a form of transmission via an additionally installed signal line may be adopted, or a power supply line A mode in which the data is transmitted while being superimposed on the screen may be employed, or a mode in which the data is transmitted by wireless communication may be employed.

  As a common contrivance for the first to third embodiments, a mode in which the display control unit 22 displays a symbol simulating the white line of the own lane on the captured image on the display 40 is considered. Hereinafter, this aspect will be described.

  Specifically, as shown in FIG. 11, a symbol 80 simulating a white line of the own lane is superimposed on the image and displayed on the display 40. Here, as the width of the symbol 80, a fixed value obtained and stored in advance based on a general traveling lane width may be used. In addition, a white line is extracted by a conventionally known Hough transform technique from an image captured by the rear camera 10 during daytime forward movement, and an average driving lane width is obtained from the extraction result to obtain the average The value may be used as the width of the symbol 80. That is, after correcting the distortion of the image obtained by imaging, the white line is extracted by using a straight line extraction technique based on the Hough transform using the fact that the white line is displayed as a straight line in the corrected image. An average traveling lane width may be obtained from the result, and the average value may be used as the width of the symbol 80. Here, instead of the image obtained by imaging with the rear camera 10, an image obtained by imaging with the front camera 30 of FIG. 2 may be used. Further, when traveling on a road where no white line exists, it is effective to use a fixed value obtained in advance based on a general traveling lane width.

  As for the direction of the symbol 80, the direction of the symbol 80 is changed according to the steering angle of the steering wheel by applying the technique of the third embodiment as shown in FIG.

  As described above, the symbol 80 simulating the white line of the own lane is superimposed on the image and displayed on the display 40. For example, the following vehicle 75 shown in FIG. 11 is traveling on a lane different from the own vehicle. And the driver can easily judge visually. That is, it becomes possible to easily recognize the lane in which the following vehicle is traveling at night.

It is a figure which shows the installation position of the rear camera in a vehicle. It is a block diagram which shows the structure of a camera system. It is a figure which shows the image of the rear side of the vehicle imaged with the rear camera. It is a figure which shows the photometry area | region in the case of back mode. It is a figure which shows the photometry area | region in the case of rear side monitoring mode. It is a flowchart which shows the process sequence in the camera system of 1st Embodiment. It is a figure which shows the photometry area | region of the predetermined size containing a high-intensity area | region. It is a flowchart which shows the process sequence in the camera system of 2nd Embodiment. It is a figure which shows the photometry area | region after changing according to the steering angle of a steering wheel. It is a flowchart which shows the process sequence in the camera system of 3rd Embodiment. It is a figure which shows the example which superimposed and displayed the symbol which simulated the white line of the own lane on the image.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Camera system, 2 ... Vehicle, 10 ... Back camera, 11 ... Image sensor, 12 ... AGC, 13 ... AD converter, 14 ... DSP, 15 ... Encoder, 16 ... Photometry part, 17 ... Imaging condition adjustment part, 18 ... Control signal receiving unit, 20 ... control unit, 21 ... camera control unit, 22 ... display control unit, 23 ... mode determination unit, 24 ... night determination unit, 30 ... front camera, 40 ... display, 50 ... vehicle speed detection unit, 60 ... rudder angle detection unit, 70 ... white line, 71 ... horizontal line, 72 ... following vehicle, 73 ... high brightness area, 74 ... following vehicle, 75 ... following vehicle, 80 ... symbol.

Claims (4)

The camera installed on the vehicle is switched between a first mode for imaging the rear and side of the vehicle during the backward movement of the vehicle and a second mode for imaging the rear and side of the vehicle during the forward movement of the vehicle. A camera system that takes an image of the rear and sides of the camera and displays the captured image on a display device installed in the vehicle,
A mode determination unit that determines whether the current imaging state is the first mode or the second mode based on a predetermined condition;
A night determination unit that determines whether the current time is night based on a predetermined condition;
When the mode determination unit determines that the imaging state is the second mode and the night determination unit determines that the current time is night, than the photometric area when the imaging state is the first mode, A photometric control unit that performs photometry on a relatively upper area in the imaging area of the camera;
An imaging condition adjusting unit that adjusts an imaging condition by the camera based on a photometric result by the photometric control unit;
Camera system equipped with. The photometry control unit
In photometry of the upper area, it is determined whether or not there is one or more high-brightness areas whose luminance is higher than a predetermined threshold in the upper area. 2. The camera system according to claim 1, wherein the photometry is performed by focusing on a photometry area having a predetermined size including the high brightness area. The camera system further includes a steering angle detection unit that detects a steering angle of a steering wheel of the vehicle,
The said photometry control part changes the area | region of photometry object according to the steering angle of the steering wheel detected by the said steering angle detection part, and measures the area | region after a change. Camera system.   The camera system according to any one of claims 1 to 3, further comprising a display control unit configured to superimpose a symbol simulating a white line of the own lane on the captured image and to display the symbol on the display device.

Images