JP4734727B2 - Video camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a video camera that is suitable for use in, for example, a vehicle mounted on an automobile and monitoring the rear or side of the automobile.
[0002]
[Prior art]
In recent years, a so-called back monitor in which a video camera is attached to the rear part of a vehicle such as an automobile and an image taken by the video camera is displayed on a monitor arranged at a predetermined position in the car is known. Various practical applications. This back monitor is mainly used to improve the safety at the time of back by allowing the rear of the blind spot from the driver's seat to be confirmed on the monitor when the vehicle is moved backward. As a monitor in this case, a monitor installed in a car as a so-called car navigation device for displaying a road map in the vicinity of the current position during travel is often used. In addition, a display device dedicated to the back monitor may be arranged near the driver's seat.
[0003]
[Problems to be solved by the invention]
By the way, as a video camera used as a conventional back monitor, a relatively small normal video camera is often used as it is. That is, as a signal processing system included in the video camera, adjustments such as automatic white balance adjustment (AWB) and automatic gain adjustment (AGC) are performed so that the adjustment level is always at an optimum level. When the brightness of the object is high (that is, when the illuminance of the subject is equal to or higher than the minimum illuminance), good color reproduction is performed and the output signal level is also controlled to be substantially constant. When the brightness is less than the minimum illuminance, the captured image becomes dark and the captured object cannot be confirmed.
[0004]
However, since an automobile sometimes travels at night, it is not preferable that the image projected on the back monitor becomes dark at night and the photographed object cannot be confirmed.
[0005]
In order to solve this problem, it is conceivable that some illumination means is provided in the vicinity of the video camera to illuminate the area captured by the video camera so that the illuminance of the subject is equal to or higher than the minimum illuminance. Providing such illumination means complicates the configuration as a back monitor. Further, depending on the vehicle to be mounted, it may be difficult to provide illumination means.
[0006]
This section describes problems with a back monitor installed in a vehicle such as an automobile, but it is used when the change in brightness of the place where the image is taken for monitoring is large, such as in the day and night. Various video cameras have similar problems.
[0007]
SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a video camera that can shoot well without requiring illumination or the like, regardless of whether the subject is bright or dark.
[0008]
[Means for Solving the Problems]
The present invention relates to an imaging unit that converts image light into an electrical imaging signal, a processing unit that processes an imaging signal output from the imaging unit to obtain a video signal of a predetermined method, and a processing state in the processing unit Control means for selectively setting a first processing state corresponding to when the image light has a predetermined brightness or higher and a second processing state corresponding to the image light having a brightness lower than the predetermined. It is equipped with. Then, as processing of the imaging signal by the processing means, imaging that includes an infrared band in either the first processing state or the second processing state without performing processing for cutting the infrared signal included in the imaging signal. While processing the signal, in the first processing state, the gain of the amplification unit included in the processing unit is variably set according to the input level, and the white balance adjustment unit included in the processing unit automatically adjusts the white balance according to the input level. In the second processing state, the gain of the amplification unit included in the processing unit is set to a predetermined value, and the white balance adjustment unit included in the processing unit does not perform automatic white balance adjustment, and the predetermined white balance adjustment state is performed. It was made to fix to.
[0009]
By doing so, the processing state of the imaging signal in the processing means changes according to the brightness of the subject, and the video signal output by this video camera is whatever the brightness of the subject. The subject can be always confirmed satisfactorily by the display on the display device.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
[0011]
In this example, it is a video camera for a so-called back monitor that monitors the rear mounted on an automobile traveling on a road. FIG. 1 is a block diagram showing the overall configuration of the video camera. The video camera 10 of this example forms image light of a subject on the surface of an image pickup device (imager) in the image pickup unit 12 via an optical system 11 such as a lens and an iris. As the image sensor, a CCD image sensor, a CMOS image sensor, or the like is used. The imaging unit 12 performs a process of outputting an imaging signal corresponding to the image light incident on the imaging element.
[0012]
Note that the image sensor provided in the imaging unit 12 of the present example can capture a subject with high sensitivity in color when the brightness is equivalent to daytime, and has a certain degree of sensitivity when the brightness is dark corresponding to nighttime. In this case, an image pickup device is used, but it is difficult to accurately reproduce the color of the subject. The minimum illuminance that can be captured by the image sensor, described below, is the lowest illuminance (brightness) that allows the subject to be imaged in color with high sensitivity. Will be.
[0013]
The imaging signal output from the imaging unit 12 is supplied to the front end unit 13. The front end unit 13 performs automatic gain control (AGC) that stabilizes the level of the supplied imaging signal (analog signal) within a certain range, and a signal on which the AGC processing is performed (however, when the AGC processing is not performed). The sampled digital data is supplied to a digital signal processor (hereinafter referred to as DSP) 14. The DSP 14 performs a process of converting imaged data into a signal having good characteristics by digital processing and converting it into video data of a standard such as the NTSC system.
[0014]
The timing generator 17 generates a synchronization signal in synchronization with the data processing in the DSP 14, and the imaging process is performed in the imaging unit 12 in synchronization with the synchronization signal generated by the timing generator 17. .
[0015]
The video data processed by the DSP 14 is supplied to the video signal output terminal 16 via the video buffer 15. When the video signal output from the output terminal 16 is an analog signal, an analog / digital converter is connected to the subsequent stage of the video buffer 15. The output terminal 16 is connected to the display device 1 configured by a liquid crystal display or the like, and an image captured by the video camera 10 is displayed on the display device 1.
[0016]
The DSP 14 that processes image data performs image processing (video processing) such as automatic white balance adjustment (AWB) to improve the signal characteristics. The processing in the DSP 14 is executed under the control of the control unit 18. Data stored in the first or second ROM 21 or 22 is used as parameters necessary for processing in the DSP 14 and processing in peripheral circuits such as the front end unit 13. These ROMs 21 and 22 are composed of, for example, an EEPROM, and parameters are written at the time of manufacture or the like.
[0017]
One of the outputs of the two ROMs 21 and 22 is selected by the changeover switch 23 and supplied to the DSP 14. Switching of the changeover switch 23 is controlled by the control unit 18. Therefore, parameters stored in the ROM 21 connected via the changeover switch 23 are used for signal processing.
[0018]
The parameters stored in the first ROM 21 are parameters for normally operating processing functions provided in the DSP 14 and peripheral circuits such as automatic white balance adjustment (AWB) and automatic gain adjustment (AGC). The parameters stored in the second ROM 22 include an image that allows the subject to be confirmed from an image displayed on the display device when an object having an illuminance less than the minimum illuminance that can be normally imaged by the imaging unit 12 is imaged. It is a parameter to do. Details of the processing state by the parameters stored in these two ROMs 21 and 22 will be described later.
[0019]
Further, the video camera 10 of this example has a built-in brightness sensor 19 for detecting the brightness of the surroundings where the video camera 10 takes a picture. The brightness data detected by the sensor 19 is determined by the control unit 18, and the switching control of the selector switch 23 is performed based on the determination.
[0020]
FIG. 2 is a flowchart showing an example of setting the signal processing state based on the output of the brightness sensor 19 in this example. The process will be described with reference to the flowchart of FIG. 2. First, the control unit 18 determines that the brightness around the video camera 10 (that is, the brightness of the subject) exceeds the minimum illuminance that can be normally captured by the imaging unit 12 from the output of the sensor 19. It is determined whether or not (step S11). In this determination, when it is determined that the illuminance is higher than the minimum illuminance at which normal imaging can be performed, the first ROM 21 is selected by the changeover switch 23, and the parameters stored in the first ROM 21 are used for signal processing by the DSP 14 or the like. Use (step S12). Then, the parameters stored in the ROM 21 are set in the DSP 14 and the front end unit 13, and the image pickup signal supplied from the image pickup unit 12 is processed as a video signal with good characteristics (step S13). The parameters read and set from the ROM 21 in step S13 are parameters for performing a normal imaging operation when the brightness is equal to or higher than the minimum illuminance.
[0021]
As a specific processing example in step S13, for example, an automatic gain control (AGC) that sets the level of the imaging signal input to the front end unit 13 to a substantially constant range using the variable gain amplifier in the front end unit 13 is used. ) Processing and automatic white balance adjustment (AWB) processing for adjusting the balance of the three primary color signals R, G, and B constituting the color video signal in the DSP 14. By setting these processing states with the parameters read from the ROM 21, the level of the output video signal is within an appropriate range, and the white balance is also adjusted correctly. Processing with this parameter is executed until a change in brightness is detected in step S11.
[0022]
When the control unit 18 determines that the illuminance is less than the minimum illuminance that can be normally imaged in step S11, the second switch 22 is selected by the changeover switch 23, and the parameter stored in the second ROM 22 is changed to the DSP 14 or the like. (Step S14). Then, the parameters stored in the ROM 22 are set in the DSP 14 and the front end unit 13, and the image pickup signal supplied from the image pickup unit 12 is processed as a video signal with good characteristics (step S15). The parameters read and set from the ROM 22 in step S15 are parameters for performing an imaging operation when the brightness is less than the minimum illuminance.
[0023]
As a specific processing example in step S15, for example, the gain of the variable gain amplifier for AGC processing in the front end unit 13 is set to a fixed value. For example, a relatively low gain is set. As the fixed value here, a predetermined fixed value may be set, or a fixed value selected from a plurality of stages according to the situation at that time may be set. Further, as white balance adjustment in the DSP 14, automatic white balance adjustment corresponding to the input level is not performed, and a fixed white balance adjustment value indicated by a parameter is set. As this fixed white balance adjustment value, for example, a white balance adjustment value of a color temperature that can correctly reproduce the color of an object illuminated by a streetlight or a headlight of an automobile is used.
[0024]
By setting these processing states with parameters read from the ROM 22, a video signal for displaying a good video can be output even in a dark situation where the illuminance of the subject is low. That is, for example, by suppressing the gain of the variable gain amplifier for AGC processing and improving the S / N ratio, the sensitivity can be increased apparently, and a subject photographed in a dark situation can be appropriately displayed from the display on the display device. Can be confirmed. Further, since automatic white balance adjustment is not performed, erroneous white balance adjustment is not performed, and a signal having a color significantly different from the actual color is prevented. Processing with this parameter is executed until a change in brightness is detected in step S11.
[0025]
In the case where the processing state is changed according to the brightness as shown in the flowchart of FIG. 2, for example, the infrared signal cut filter which is one of the processing functions that can be executed by the DSP 14 is set to the non-operating state in any mode. Even when imaging is performed, an imaging signal including a band of an infrared signal is processed. In this way, particularly when the processing of steps S14 and S15 is performed (that is, when the mode corresponds to nighttime), a relatively sensitive signal included up to the band of the infrared signal is processed. Even when shooting, it is possible to display an image that allows the subject to be confirmed.
[0026]
Or you may make it remove an infrared signal component with an infrared signal cut filter irrespective of the case where it processes in the case where it processes by step S13 and step S15. Furthermore, the case where the infrared signal cut filter is activated and the case where it is not activated may be selected according to the brightness.
[0027]
The flowchart of FIG. 3 is an example of processing when the infrared signal cut filter is selectively used. That is, the control unit 18 determines whether or not the minimum illuminance is higher than the output of the sensor 19 (step S21). In this determination, when it is determined that the illuminance is higher than the minimum illuminance at which normal imaging can be performed, the first ROM 21 is selected by the changeover switch 23, and the parameters stored in the first ROM 21 are used for signal processing by the DSP 14 or the like. When used (step S22), the infrared signal cut filter prepared in the DSP 14 or the like is operated (step S23). Then, the parameters stored in the ROM 21 are set in the DSP 14 and the front end unit 13, and the image pickup signal supplied from the image pickup unit 12 is processed as a video signal with good characteristics (step S25).
[0028]
When the control unit 18 determines that the illuminance is lower than the minimum illuminance that can be normally imaged in step S21, the second ROM 22 is selected by the changeover switch 23, and the parameters stored in the second ROM 22 are changed to the DSP 14 or the like. (Step S25), the infrared signal cut filter prepared in the DSP 14 or the like is deactivated, and the infrared signal component included in the imaging signal is not cut (step S26). Then, the parameters stored in the ROM 22 are set in the DSP 14 and the front end unit 13, and the image pickup signal supplied from the image pickup unit 12 is processed as a video signal with good characteristics (step S27).
[0029]
By performing the processing as shown in the flowchart of FIG. 3, the signal component in the band of the infrared signal included in the imaging signal is removed during imaging in a bright situation so that a good image with good image quality can be displayed. Become. Further, when imaging in a dark situation, it is possible to perform imaging with high sensitivity by using an infrared signal component, and it is possible to display an image with high sensitivity even in a situation where there is no bright illumination.
[0030]
Next, an installation example of the video camera of this example will be described. FIG. 4 is a diagram showing an example of mounting on the vehicle m when the video camera 10 of this example is used as a back monitor for the vehicle. The video camera 10 is disposed at the rear end of the automobile m and images the rear of the automobile m. The display device 1 connected to the video camera 10 is disposed in front of the driver's seat of the automobile m and at a position that does not obstruct the field of view in front of the driver. Note that the image displayed on the display device 1 is usually in the same direction as the image displayed on the inside mirror (so-called room mirror) as a mirror image with the left and right reversed.
[0031]
The display device 1 may also be used as a display device for a navigation device. That is, for example, as shown in FIG. 5, the video signal captured and output by the video camera 10 is supplied to the external video input terminal of the navigation device 2, and the video signal output from the navigation device 2 is supplied to the display device 1. To be configured. Based on the backward signal obtained at the backward signal input terminal 3 of the navigation device 2, the video supplied from the navigation device 2 to the display device 1 is automatically selected. Specifically, for example, when a backward signal is obtained at the input terminal 3, a video signal from the video camera 10 is supplied to the display device 1, and at other times, a video signal such as a road map generated by the navigation device 2 is displayed. Supply to device 1.
[0032]
A reverse signal is generated at the reverse signal input terminal 3 when the lever is set to a reverse position by a gear change operation using a shift lever or the like of the automobile m. The navigation device 2 and the control circuit on the vehicle m side are electrically connected by supplying a reverse signal generated by a control circuit (not shown) on the vehicle m side to the input terminal 3 via a photocoupler. You may make it isolate | separate into.
[0033]
With the configuration as shown in FIG. 5, only when the vehicle m is moved backward, the display device 1 connected to the navigation device 2 displays the rear image captured by the video camera 10, and the back of the vehicle m is displayed. The monitor display device can also be used as the navigation device display device. In the case of the system configuration as shown in FIG. 3, an image captured by the video camera 10 is displayed on the display device 1 by, for example, operation of an operation key of the navigation device instead of automatic switching by a backward signal. You may make it switch so that.
[0034]
By using the video camera 10 of this example for a video camera used as a back monitor for an automobile as shown in FIG. 4 or FIG. 5, it is displayed on the display device 1 in both daytime and nighttime. Will be able to check backwards better. That is, when the vehicle is running in the daytime and the surroundings are relatively bright, an imaging process suitable for the daytime brightness is performed, and a good image with good image quality is displayed on the display device 1. Become. Also, when driving at night and the surroundings are dark, imaging processing suitable for night is performed, and even if there is some degradation in image quality, processing that increases the apparent sensitivity is performed, An image for confirming the subject is displayed on the display device 1.
[0035]
The video camera 10 having the configuration shown in FIG. 1 has a configuration in which outputs of a plurality of memories storing parameters for setting a processing state in the DSP or the like are switched to be supplied to the DSP by a changeover switch. The switch may be omitted, and a necessary parameter may be selected from a plurality of parameters by internal processing in a DSP or the like. For example, like the video camera 10 ′ shown in FIG. 6, the data stored in the two ROMs 21 and 22 are directly supplied to the DSP 14, and the switch 14 a virtually configured in the DSP 14 is switched. The control unit 18 'may be configured to perform processing using only the parameters stored in one of the ROMs. The ROMs 21 and 22 may function as two memories by dividing a storage area of one memory into a plurality of areas. The other parts of the video camera 10 ′ shown in FIG. 6 are configured in the same manner as the video camera 10 shown in FIG.
[0036]
Further, in the video camera 10 having the configuration shown in FIG. 1, the daytime processing and the nighttime processing are automatically switched based on the output of the brightness sensor. May be performed. For example, like the video camera 10 ″ shown in FIG. 7, this video camera 10 ″ is provided with an operation key 24, and the operation key 24 is operated to select a daytime processing mode and a nighttime processing mode. The control unit 18 ″ may determine the key operation so that the parameter supplied to the DSP 14 by switching the changeover switch 23 or the like may be set to the corresponding mode. The video shown in FIG. Other parts of the camera 10 ″ are configured in the same manner as the video camera 10 shown in FIG.
[0037]
In the above-described embodiment, automatic white balance adjustment (AWB) and automatic gain adjustment (AGC) have been described as processing to be changed between daytime processing and nighttime processing. However, other signal processing states are changed. You may do it. In addition, the processing state in an optical system such as auto iris may be changed between daytime processing and nighttime processing.
[0038]
In the above-described embodiment, the example in which the video camera is applied as a camera for a back monitor of an automobile has been described. However, the same processing may be performed by a video camera used for other purposes.
[0039]
【The invention's effect】
According to the present invention, the processing state of the imaging signal in the processing means changes according to the brightness of the subject, and the display device for the video signal output by the video camera regardless of the brightness of the subject With the display at, the subject can always be confirmed satisfactorily. Therefore, for example, when used as a video camera for a back monitor for a vehicle, the rear portion of the vehicle can be monitored both day and night.
[0040]
In this case, as the processing of the imaging signal by the processing means, the processing of cutting the infrared signal included in the imaging signal is not performed, and the imaging signal including the band of the infrared signal is processed as the first or second processing state. In this way, an output video signal is obtained using a signal containing signal components in the infrared band, and an image that can recognize the subject well even when the subject is dark is displayed. Become.
[0042]
Further, a brightness detection unit around the video camera is provided, and the control unit controls selection of the first processing state and the second processing state in accordance with the detection output of the brightness detection unit, so that the subject can be detected. Processing when the subject is bright and processing when the subject is dark are automatically switched.
[0043]
Further, in the first processing state, the gain of the amplification unit included in the processing unit is variably set according to the input level, and in the second processing state, the gain of the amplification unit included in the processing unit is set to a predetermined value. Thus, when the subject is bright, it is possible to generate a video signal with a good characteristic whose level is controlled to be constant. When the subject is dark, for example, the gain of the amplifying unit is fixed and the subject is recognized. It is possible to generate a video signal that can be generated.
[0044]
Further, in the first processing state, automatic white balance adjustment is performed by the white balance adjustment unit provided in the processing unit, and in the second processing state, automatic white balance adjustment is performed by the white balance adjustment unit provided in the processing unit. As a result, when the subject is bright, it is possible to generate a video signal with good characteristics that is automatically adjusted for white balance. It is possible to prevent an erroneous operation of the balance adjustment, prevent the actual color and the displayed color from greatly changing, and generate a good video signal.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a system configuration example according to an embodiment of the present invention.
FIG. 2 is a flowchart showing an example of processing based on brightness according to an embodiment of the present invention.
FIG. 3 is a flowchart showing a processing example based on brightness (an example in which an infrared cut filter is selectively used) according to an embodiment of the present invention.
FIG. 4 is a perspective view showing an installation example of a system according to an embodiment of the present invention.
FIG. 5 is a block diagram showing an example in which a camera according to an embodiment of the present invention is connected to a navigation device.
FIG. 6 is a block diagram showing a configuration example according to another embodiment of the present invention.
FIG. 7 is a block diagram showing a configuration example according to still another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Display apparatus, 2 ... Navigation apparatus, 3 ... Backward signal input terminal 10, 10 ', 10 "... Video camera, 11 ... Optical system, 12 ... Imaging part, 13 ... Front end part, 14 ... Digital signal processor ( DSP), 14a ... switching unit, 15 ... video buffer, 16 ... video signal output terminal, 17 ... timing generator, 18 ... control unit, 19 ... brightness sensor, 21, 22 ... ROM, 23 ... changeover switch, 24 ... operation Key

Claims (3)

Imaging means for converting image light into an electrical imaging signal;
Processing means for processing an imaging signal output by the imaging means to obtain a video signal of a predetermined method;
As a processing state in the processing means, a first processing state corresponding to the case where the image light has a predetermined brightness or higher and a second processing corresponding to the case where the image light has a brightness lower than a predetermined level. Bei example and control means for selectively setting a state,
As the processing of the imaging signal in the processing means, the processing that cuts the infrared signal included in the imaging signal is not performed, and the imaging including the infrared band is included in both the first processing state and the second processing state. While processing the signal,
In the first processing state, the gain of the amplification unit included in the processing unit is variably set according to the input level, and the white balance adjustment unit included in the processing unit performs automatic white balance adjustment according to the input level,
In the second processing state, the gain of the amplification unit included in the processing unit is set to a predetermined value, and automatic white balance adjustment is not performed in the white balance adjustment unit included in the processing unit, and the predetermined white balance adjustment state is performed. Video camera to be fixed . The video camera according to claim 1.
The gain when the amplification unit is the predetermined value in the second processing state is a relatively low gain,
The predetermined white balance adjustment state in the white balance adjustment unit in the second processing state is a white balance adjustment state in which an object illuminated by the light of the vehicle is correctly displayed.
Video camera. The video camera according to claim 1 or 2 ,
A video camera provided with brightness detection means around the video camera, and the control means controls selection of the first processing state and the second processing state in accordance with the detection output of the brightness detection means.

Images