JP2007043392A - Vehicle mount imaging apparatus and on-vehicle camera system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle surrounding confirmation apparatus that properly discriminates whether or not a video image from a camera installed in a vehicle depending on a state of the vehicle so as to be capable of preventing malfunction. <P>SOLUTION: A vehicle mount imaging apparatus including an imaging optical system 13 with lenses 1 to 4, and an imaging element 6 for converting an image of an object via the imaging optical system 13 into a video image displayed on a display apparatus 15 is configured such that a ratio of a horizontal magnification to a vertical magnification in the imaging optical system 13 takes a value between a conversion coefficient used for converting a first aspect ratio of the imaging element 6 into a second aspect ratio of the display apparatus 15 and the unity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an in-vehicle imaging device that mainly monitors the surroundings of an automobile and displays an image of the surroundings of the vehicle as an image on a display in the vehicle, and an in-vehicle camera system using the in-vehicle imaging device. Further, the present invention relates to an image sensor having an aspect ratio different from that of a display device used in the image pickup apparatus.

  2. Description of the Related Art Conventionally, there has been disclosed a technique for setting a situation outside an automobile with an imaging camera and displaying a landscape or an object on the rear, front or side of the vehicle on a display. In recent years, for in-vehicle applications, a technology has been disclosed that converts the aspect ratio of an image sensor used in an imaging device and the aspect ratio of a display in a vehicle, or obtains an image that is widely imaged in the horizontal direction. Yes.

  In this type of conventional technology, it is disclosed that a wide-angle image is obtained by using a fish-eye lens, and this image is subjected to image processing to obtain an image with little distortion (see, for example, Patent Document 1).

  In another conventional technique, a cylindrical lens is used as the imaging lens of the imaging camera, and the subject image is optically compressed in one of horizontal and vertical directions, thereby widening the angle of view of the imaging camera. It is disclosed that the imaging range is increased (see, for example, Patent Document 2).

In another conventional technique, it is disclosed that a plurality of cameras with a narrow angle of view are arranged side by side, and an image capturing range is enlarged by combining images of overlapping portions (see, for example, Patent Document 3). .
JP 2002-366937 A JP 2000-278670 A JP 2000-175182 A

  However, in the technique of Patent Document 1, when a wide angle image is obtained using a fisheye lens, a wide angle image is obtained. However, since the peripheral side portion is greatly distorted from the center of the image, the image processing becomes complicated, and the image There is a problem that the scale of processing must be large. In general, in order to improve the resolution from the center to the periphery of the fisheye lens, it is necessary to increase the number of lenses of the imaging camera, so that there is a problem that the lens becomes large and hinders downsizing of the apparatus. Yes.

  On the other hand, in the technique of Patent Document 2, it is easy to widen the angle of view in one direction of horizontal or vertical when using a cylindrical lens, but the resolution of the image can be improved only by changing the magnification ratio in one direction. There is a problem that improvement is basically difficult. Therefore, similarly to the case of Patent Document 1, the technique of Patent Document 2 has a problem that the peripheral portion of the image is greatly distorted and it is necessary to perform complicated image processing to obtain an image with good visibility. Therefore, even if complicated image processing is performed, an image that is not necessarily good in visibility is generated.

  Furthermore, since the technique of Patent Document 3 requires a plurality of cameras and image sensors, there is a problem in that downsizing of the entire system is hindered and complicated incidental work such as camera attachment and adjustment increases. .

  The present invention has been made in order to solve the conventional problems. When the aspect ratio of the image sensor and the aspect ratio of the display device are different, the present invention is capable of miniaturization and displays a wide-angle image on the screen with high resolution. An in-vehicle imaging device and an in-vehicle camera system that can be used are provided.

  An in-vehicle image pickup apparatus according to the present invention is mounted on a vehicle including an image pickup optical system including a lens and an image pickup element that converts an image of a subject through the image pickup optical system into an image displayed on a display. An image pickup apparatus for converting a ratio of a horizontal magnification and a vertical magnification of the imaging optical system from a first aspect ratio of the imaging element to a second aspect ratio of the display It has a configuration with a value between the conversion coefficient and 1.

  With this configuration, when the aspect ratio of the image sensor and the aspect ratio of the display device are different, the display device has a ratio between the horizontal magnification and the vertical magnification of the image pickup optical system from the first aspect ratio of the image pickup device. Since the conversion factor for conversion to the second aspect ratio is a value between 1, the magnification of vertical and horizontal enlargement / reduction can be set to the same degree as each magnification of the imaging optical system. Become. Thereby, since the horizontal / vertical magnification is not set extremely, it is possible to prevent the distortion of the image from being increased in the display on the display device. In other words, the information amount of light from the subject incident on the image sensor acts to complement the difference in aspect ratio between the image sensor and the display device. In other words, when the image is displayed on the display device, the amount of light information from the incident subject that is input from the imaging optical system to the image sensor is increased in the direction in which the image is greatly enlarged. In order to operate, even when enlarged, the image is less distorted and the image can be displayed on the screen at a high resolution.

  In the in-vehicle imaging device of the present invention, the first aspect ratio or the second aspect ratio has a configuration in which the horizontal direction of the aspect ratio is larger than the vertical direction of the aspect ratio.

  With this configuration, it is possible to reduce distortion of an image with a large horizontal angle of view that is required as an in-vehicle imaging device.

  In the in-vehicle imaging device of the present invention, at least one of the lenses has an aspherical shape that is axially asymmetric with respect to the optical axis, and the horizontal magnification of the imaging optical system is equal to the imaging optical system. It has a configuration smaller than the vertical magnification.

  With this configuration, the horizontal direction can be configured to have a wider angle, which enables downsizing and further reduces distortion of a video with a large horizontal angle of view. realizable.

  Moreover, the vehicle-mounted imaging device of this invention has the structure which mainly images the back with respect to the advancing direction of the said vehicle.

  With this configuration, it is possible to confirm with high visibility the rear side of the vehicle, which tends to be a driver's blind spot when rearward monitoring such as garage entry is performed.

  In the in-vehicle imaging device of the present invention, the first aspect ratio is a ratio in which the vertical direction is 3 and the horizontal direction is 4, and the second aspect ratio is 9 in the vertical direction. The horizontal direction is a ratio of 16.

  With this configuration, an image sensor with an aspect ratio of 3: 4 that is normally used can be used, so the range of use of the image sensor when used in an in-vehicle image pickup device can be expanded, and the degree of freedom in design can be expanded. it can. In addition, since a display having a 9:16 aspect ratio, which is frequently used for navigation displays, can be displayed, it is unnecessary to prepare a new display, the cost can be reduced, and the imaging device can be easily installed. Since it is possible to monitor the surroundings in addition to the vehicle, there is also an advantage that convenience is high.

  Moreover, the vehicle-mounted imaging device of this invention has the structure arrange | positioned above the driver's seat of the said vehicle.

  With this configuration, monitoring from a viewpoint higher than the driver's position is possible, and the planar blind spot of the vehicle can be reduced. This makes it easier to monitor the surroundings.

  The in-vehicle camera system of the present invention has a configuration including the in-vehicle imaging device of the present invention and the display installed in the vehicle.

  With this configuration, it is possible to realize an in-vehicle camera system that can be downsized with a wide angle and high visibility.

  As described above, the present invention provides a vehicle-mounted imaging device and a vehicle-mounted camera system that can be reduced in size and can display wide-angle images on a screen with high resolution.

  Hereinafter, an in-vehicle imaging device and an in-vehicle camera system according to embodiments of the present invention will be described with reference to the drawings.

  1 and 2 are diagrams illustrating an example of a configuration of an imaging apparatus according to an embodiment of the present invention. FIG. 1 is a vertical sectional view of the imaging device when mounted on a vehicle, and FIG. 2 is a horizontal sectional view when mounted on the vehicle. Note that the in-vehicle imaging device according to the embodiment of the present invention displays an image obtained by imaging a subject on a display (not shown).

  As shown in FIG. 1, the imaging device 12 includes an imaging optical system 13 and an imaging element 6, and the imaging optical system 13 includes a first lens 1, a second lens 2, a third lens 3, an aperture 5, And the fourth lens 4.

  The light beam passes through the first lens 1, the second lens 2, the third lens 3, the diaphragm 5, and the fourth lens 4 from the left direction in the figure and forms an image on the image sensor 6. The light beam 8 near the center axis 7 (optical axis) of the image pickup optical system 13 forms an image at a point A of the image pickup device 6, and the light beam 9 is gradually bent and condensed by the lenses 1 to 4 to be collected. The image is formed at point B.

  Each lens is made of an optical glass such as Schott BK7 (ne = 1.52) or HOYA TaF1 (ne = 1.78), Zeonex Z480R (ne = 1.53) or PC (ne = 1). .55) is used.

  The diaphragm 5 is an optical diaphragm, and is a shielding plate that limits the range of transmitted light rays in order to improve imaging performance. In the embodiment of the present invention, the diaphragm 5 has a transmittance in the visible light region of about 0.1% or less, and black matte coating is applied to both surfaces of a 0.1 mm thick plate such as a resin (such as PET). Use what you gave. In addition, the diaphragm 5 is disposed between the third lens 3 and the fourth lens 4, but may be disposed between other lenses as long as the same effect can be obtained.

  The image pickup device 6 has a ratio of the vertical direction to the horizontal direction (aspect ratio) of its outer shape of 3: 4, and has a size such as 1/4 inch, 1/3 inch, or 1/6 inch. That's it. The number of pixels of the image sensor 6 is 250,000 pixels, 370,000 pixels, 1 million pixels, or the like.

  In the embodiment of the present invention, an axially asymmetric lens is used for the second lens 2. In FIG. 2, for convenience, the horizontal second lens 2 shown in FIG. 1 is referred to as a second lens 10, and different symbols are used. In FIG. 2, the shape of the second lens 2 in the horizontal direction is indicated by a broken line in the second lens 10.

  A general lens has a rotationally symmetric shape and is symmetric around the optical axis. In the embodiment of the present invention, since the second lens 2 (second lens 10) has different surface shapes in the vertical and horizontal directions, the way of bending the light beam in each direction is different. The shape of the second lens 2 (second lens 10) is an aspherical shape, and has a function of correcting aberrations in the same way as a normal aspherical lens.

  Further, when comparing the shapes of the second lenses 2 in the respective directions, the curvature of the lens surface 2a is greater between the vertical lens surface 2a shown in FIG. 1 and the horizontal lens surface 10a shown in FIG. The lens surface 10b is smaller in curvature than the lens surface 2b and the lens surface 10b.

  Therefore, the lens 10 has a stronger power as a concave lens than the lens 2, and as a result, the lens 10 has a shorter focal length than the lens 2, and not only the luminous flux 9 but also the peripheral luminous flux 11. Can be imaged at point B of the image sensor 6. In this case, if the focal length in the horizontal direction is fh, the focal length in the vertical direction is fv, the magnification in the horizontal direction is βh, and the magnification in the vertical direction is βv, then for a subject at a certain distance, βh <βv It is known as known. That is, the magnification is set in the horizontal and vertical directions.

  3 and 4 are schematic views of an in-vehicle camera system using the imaging device according to the embodiment of the present invention. FIG. 3 is a view of the vehicle as viewed from the side, and FIG. 4 is a view of the vehicle as viewed from above. The in-vehicle camera system captures an image of the surroundings of the vehicle, mainly behind the vehicle, with the imaging device 12 and displays an image of the captured image on the display 15 in the vehicle.

  For example, the imaging device 12 is installed on the rear side of the vehicle body 14 in a state of being wrapped in a case, and images the state behind the traveling direction. In addition, in the image behind the vehicle body 14, since a wider field of view is required to be visible, the horizontal angle of view C should be 100 ° or more, preferably about 130 ° or more, and more preferably about 160 ° or more. Good.

  For example, when the image captured by the imaging device 12 is displayed on the display 15 used in the car navigation device installed on the driver's seat side, the driver monitors the rear such as entering a garage, Even if you do not look back, you can check both sides of the rear of the vehicle, which are likely to be blind spots, with high visibility.

  In general, an image sensor constituting an imaging apparatus having a rotationally symmetric lens has a ratio (aspect ratio) between the vertical direction and the horizontal direction of 3: 4. On the other hand, the aspect ratio of a display such as a car navigation is generally 9:16. Therefore, an image pickup apparatus having a rotationally symmetric lens needs to convert the image from the aspect ratio of 3: 4 of the image pickup element to the aspect ratio of 9:16 of the display, so that the horizontal direction extends and image distortion occurs. A problem that becomes larger occurs. Further, the larger the imaging range, the worse the resolution of the image around the display screen, and the worse the visibility.

  For this reason, in the embodiment of the present invention, the horizontal magnification βh and the vertical magnification βv of the imaging optical system 13 are configured to have a relationship of βh = 0.75 × βv, thereby compressing the horizontal image, When the video is converted, the video is returned to the original video.

  FIG. 5 is a conceptual diagram of horizontal compression and video conversion to a display in the embodiment of the present invention.

  For example, the horizontal direction of an image having an aspect ratio of 9:16 is compressed by the imaging optical system 13 at a magnification ratio of βv: βh = 1: 0.75, so that 9: (16 × 0.75) = An image is captured by the image sensor 6 with an aspect ratio of 9: 12 = 3: 4. When the image pickup device 6 converts the captured image from the aspect ratio 3: 4 of the image pickup device 6 to the aspect ratio 9:16 of the display device 15 when the captured image is output to the display device 15, the image pickup device 6 is horizontal by the image pickup optical system 13. The video compressed in the direction can be restored and a good video with little video distortion can be displayed.

  Even if the ratio between the horizontal magnification βh and the vertical magnification βv is not 0.75, which is a conversion coefficient from the aspect ratio 3: 4 of the image sensor 6 to the aspect ratio 9:16 of the display device 15, If 0.75 <βh / βv <1, the imaging device 12 displays a good image with less image distortion on the screen than a rotationally symmetric lens having an imaging element with a normal aspect ratio of 3: 4. can do.

In addition, since the imaging optical system 13 is an asymmetric optical axis system, the imaging device 12 can easily perform aberration correction independent to some extent in each of the horizontal direction and the vertical direction, as compared with a rotationally symmetric lens. Even when the imaging range becomes large, it is possible to display an image with high image quality and high visibility from the center to the periphery of the image displayed on the screen.
Normally, in order to display an image with a large imaging range, the aberration is corrected by increasing the number of lenses. Conversely, since the imaging device 12 can display good image quality with a smaller number of lenses, imaging is performed. The device can be miniaturized.
In addition, since the image pickup device 12 can use an image pickup element having an aspect ratio of 3: 4, which is usually widely used for the image pickup element, the selection range of the image pickup element can be expanded, and the degree of freedom in design can be increased.

  In addition, since the imaging device 12 can display an image using the display 15 having an aspect ratio of 9:16, which is frequently used as a navigation display, it is unnecessary to prepare a dedicated display, thereby reducing costs. In addition, it is possible to easily install the imaging device 12 in the vehicle and take an image of the situation around the vehicle. Furthermore, after the imaging device 12 is installed in the vehicle, there is also a convenience that a display having an aspect ratio of 9:16 can be easily replaced.

  In FIG. 5, the imaging device 12 is attached in the vicinity of the hood of the vehicle body 14, but the imaging device 12 may be arranged above the driver's seat of the car depending on the vehicle type. With this arrangement, monitoring from a viewpoint higher than the driver's position is possible, the blind spot near the vehicle can be reduced, and the surroundings can be monitored more easily. It is possible to pick up images so that the situation around the vehicle can be seen easily.

  Furthermore, in the embodiment of the present invention, the imaging device 12 is installed at the rear of the vehicle. However, the imaging device 12 can be installed sideways or in front of the vehicle to be used as a side monitoring camera or a front side monitoring camera. Is possible.

  In the embodiment of the present invention, the number of lenses used is four and the second lens 2 is an aspherical asymmetric lens. However, the number of lenses is reduced or increased according to the angle of view, performance, and size. The same effect can be realized by arranging an aspherical asymmetric lens other than the second lens or combining a plurality of aspherical asymmetric lenses. With this configuration, it is possible to realize an in-vehicle image pickup apparatus that can be downsized and can achieve high image quality. Then, by reducing the size of the imaging device, it is possible to reduce the size of the in-vehicle camera system that captures an image of the surroundings of the vehicle and displays the surroundings as an image on the display 15 in the vehicle.

  As described above, the present invention has an effect that it is possible to reduce the size and display a wide-angle image with a high resolution on the screen, and the state around the vehicle is displayed as an image on a display in the vehicle. It is useful as an in-vehicle imaging device to be displayed and an in-vehicle camera system using the in-vehicle imaging device.

Sectional drawing of the orthogonal | vertical direction when showing an example of a structure of the imaging device in embodiment of this invention, and mounting in a vehicle 1 is a horizontal sectional view showing an example of a configuration of an imaging device according to an embodiment of the present invention and mounted on a vehicle. 1 is a schematic diagram of an in-vehicle camera system using an imaging device according to an embodiment of the present invention, and is a view of a vehicle viewed from the side. 1 is a schematic view of an in-vehicle camera system using an imaging device according to an embodiment of the present invention, and is a view of a vehicle looking down from above. Conceptual diagram of horizontal compression and video conversion to display

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st lens 2 2nd lens 3 3rd lens 4 4th lens 5 Aperture 6 Imaging element 7 Center axis 8, 9, 11 Light beam 10 2nd lens 12 Imaging device 13 Imaging optical system 14 Car body 15 Display

Claims (7)

An imaging optical system including a lens;
An in-vehicle imaging device mounted on a vehicle including an imaging element that converts an image of a subject through the imaging optical system into an image displayed on a display device,
The ratio between the horizontal magnification and the vertical magnification of the imaging optical system is between a conversion coefficient for converting the first aspect ratio of the imaging element to the second aspect ratio of the display and 1 An in-vehicle imaging device characterized by the above. The in-vehicle imaging device according to claim 1, wherein the first aspect ratio or the second aspect ratio has a horizontal direction of the aspect ratio larger than a vertical direction of the aspect ratio. At least one of the lenses has an aspherical shape that is axially asymmetric with respect to an optical axis, and a horizontal magnification of the imaging optical system is smaller than a vertical magnification of the imaging optical system. The in-vehicle imaging device according to claim 1 or 2. The in-vehicle imaging device according to any one of claims 1 to 3, wherein the rear side is mainly imaged with respect to a traveling direction of the vehicle. The first aspect ratio is a ratio in which the vertical direction is 3 and the horizontal direction is 4, and the second aspect ratio is a ratio in which the vertical direction is 9 and the horizontal direction is 16. The in-vehicle imaging device according to claim 1. The in-vehicle image pickup apparatus according to any one of claims 1 to 5, wherein the in-vehicle image pickup apparatus is disposed above a driver seat of the vehicle. An in-vehicle camera system comprising: the in-vehicle imaging device according to any one of claims 1 to 6; and the display installed in the vehicle.

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