JP5273356B2 - Compound eye image input device and distance measuring device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make compatible the securement of a resolution of distance measurement and the downsizing of a device, in a compound eye image input device for measuring a distance from a substance by utilizing a parallax generated by a compound eye. <P>SOLUTION: The compound eye image input device includes: two or more lens blocks 3a, 4a installed in a plane perpendicular to an optical axis; a single imaging means 6 for capturing images obtained by the lens blocks as a compound image; and light guiding means 3, 4 having mirror prisms 3a, 3b and mirror prisms 4a, 4b for guiding the images obtained by the lens blocks to the imaging means. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention relates to a compound eye image input device for measuring a distance from an object using parallax by a compound eye, and a distance measuring device using the same.

  Conventionally, as an apparatus for measuring a distance from an object using parallax, apparatuses as disclosed in Patent Document 1 and Patent Document 2 are known. In these devices, two or more cameras comprising a pair of an optical system and an image sensor are provided, and these devices are installed in a plane substantially perpendicular to the optical axis. It is used as a device for measuring distances, and as a camera for measuring the three-dimensional position and orientation of a subject in the security field and man-machine interface field.

  Further, Patent Document 3 discloses a device capable of measuring a distance with high resolution regardless of whether the subject is at a short distance or a long distance as a distance measuring device using compound eye parallax. .

Japanese Patent No. 3827368 Japanese Patent No. 3209828 JP 9-26318 A

  In an apparatus provided with two or more cameras as disclosed in Patent Document 1 and Patent Document 2, when the distance from the subject to the camera is long, for example, the apparatus is mounted on a car, and a car, a pedestrian, or an obstacle ahead. When measuring the distance to a subject such as an object, in order to obtain a sufficient measurement resolution, it is necessary to ensure a sufficiently long distance between the two cameras, which tends to increase the size of the apparatus. As automobiles are becoming more intelligent, there is a demand to install various sensors and cameras, such as driver monitoring and car periphery monitoring, as well as inter-vehicle distances. Therefore, it is desired to make the apparatus as small as possible while ensuring a sufficient distance resolution. Further, not only in the automobile field, but also in the security and interface fields, it is an important factor for reducing the size of equipment equipped with the device and saving space for installation.

Another problem of the conventional apparatus, there is the influence of the particular associated distance measure differences in properties and conditions of each camera using multiple cameras. Among them, the individual difference in the sensitivity of the imaging means and the synchronization of the imaging timing greatly affect the parallax detection accuracy, and how to match the characteristics and conditions among a plurality of cameras is an important issue.

  In order to ensure the distance measurement resolution, the focal length of the lens block may be increased. However, the optical magnification increases accordingly, and the image of an object at a short distance increases. When the image of the subject becomes larger than the imaging surface size of the imaging unit, the subject image cannot be specified, and it may be difficult to detect the parallax. On the other hand, if the distance to an object at a short distance can be measured, the distance measurement resolution for an object at a long distance decreases. According to the apparatus described in Patent Document 3, high-resolution processing measurement is possible regardless of the distance of the subject. However, since this apparatus uses a technique different from the optical technique and the technique using ultrasonic waves, There is a problem that becomes complicated.

  An object of the present invention is to provide a compound-eye image input device that enables both high-accuracy distance measurement in which characteristics and conditions of a compound-eye image are more closely matched while ensuring the measurement resolution of the distance and downsizing the device. The object is to realize a distance measuring device using the.

  Another object of the present invention is to provide a compound-eye image input device that makes it possible to widen the range of distance measurement while ensuring the resolution of distance measurement without complicating the device, and a distance measuring device using the same. It is to provide.

  The present invention provides a compound eye image input device that enables various purposes other than this, and a distance measuring device using the same.

The invention of claim 1 is a compound eye image input device for measuring a distance from an object using parallax by a compound eye, and has a predetermined focal length and is installed in a plane substantially perpendicular to an optical axis. A first lens block group composed of two or more lens blocks, and two or more lenses having a focal length shorter than the lens blocks in the first lens block group and disposed in a plane substantially perpendicular to the optical axis A second lens block group composed of a plurality of lens blocks, a single imaging means for capturing an image of each lens block group as a compound eye image on the same plane, and at least each lens of the first lens block group A compound eye image input device is constituted by light guiding means for folding the image of the block and guiding it to the imaging means.

The distance resolution is mainly determined by the interval between the two lens blocks and the focal length of each lens block. In the invention of claim 1, the resolution is increased by increasing the focal length instead of increasing the interval. Secure. When the focal length is increased, it is necessary to increase the imaging distance from the lens block to the imaging device. However, the imaging distance is ensured without increasing the size of the apparatus by the light guide means. In addition, the single imaging unit not only reduces the size of the apparatus, but also eliminates individual differences in sensitivity of the imaging unit and imaging timing deviation. Accordingly, it is possible to realize a compound eye image input device capable of ensuring distance measurement resolution and miniaturization of the device, and capable of highly accurate distance measurement with more consistent characteristics and conditions of compound eye images.

  In order to ensure distance measurement resolution, the optical magnification increases as the focal length of the lens block is increased, thereby increasing the image of an object at a short distance. When the image of the subject becomes larger than the imaging surface size of the imaging unit, the subject image cannot be specified, and it may be difficult to detect the parallax. On the other hand, if the distance to an object at a short distance can be measured, the distance measurement resolution for an object at a long distance decreases. As a device that enables high-resolution distance measurement regardless of whether the subject is at a short distance or a long distance, there is the device of Patent Document 3, but the device is complicated.

According to the first aspect of the present invention, the lens block group for measuring the distance of the subject is divided into a long distance measurement and a short distance measurement, and the long distance measurement lens block group (first lens block group) has a long focal length. The short-distance measuring lens block group (second lens block group) shortens the focal length, and constitutes an apparatus by integrating them. As a result, distance measurement using the long-distance measurement lens block group can ensure the distance resolution of a long-distance subject, and the short-distance measurement lens block group can reduce the optical magnification. However, distance measurement can be performed without the subject image exceeding the size of the imaging surface of the imaging means. That is, the distance measurement range can be expanded while ensuring the distance measurement resolution.
The lens blocks constituting the long-distance measurement lens block group and the short-distance measurement lens block group are installed at a predetermined interval from each other. According to the second aspect of the present invention, the lens blocks constituting the short-distance measuring lens block group are installed with a shorter interval than the lens blocks constituting the long-distance measuring lens block group.

When each image by each lens block is picked up by one image pickup means, one image cannot be composed of all the pixels of the image pickup means. For example, if an image formed by two lens blocks is formed with the same number of pixels, the number of pixels constituting one image is half of the number of pixels of the imaging means. Then, when an image formed by the two lens blocks is formed in a direction substantially parallel to the arrangement direction of the two lens blocks on the imaging surface of the imaging means, the horizontal direction of the one image (substantially parallel to the arrangement direction of the lens blocks). The number of pixels in one direction) is halved. A camera mounted on an automobile may recognize a sign or a white line using one of the images of the lens block, and in that case, the number of pixels in the horizontal direction may be important. Therefore, the reduction in the number of pixels in the horizontal direction may affect the recognition performance.

In the invention of claim 3 , each lens block and the light guide means are arranged so that the image is arranged in a direction substantially perpendicular to the optical axis of the optical system constituting the light guide means within the image pickup surface of the image pickup means. It is arranged to prevent a decrease in the number of pixels in the horizontal direction. Thereby, it is possible to prevent a reduction in the number of pixels in the horizontal direction and to prevent a reduction in recognition performance.

In the apparatus of claim 3, it may be necessary to secure a predetermined number of pixels in both the horizontal and vertical directions. In a fourth aspect of the invention, a predetermined number of pixels is secured in both the horizontal and vertical directions by making the longitudinal direction of the imaging surface substantially coincide with the arrangement direction of the images . Thereby, desired recognition performance can be ensured.

  Depending on the configuration of the light guide means, light from two or more lens blocks causes crosstalk on the image sensor surface. As a result, a part of the compound eye image by the image sensor overlaps, and the image data of the overlapped part cannot be used, resulting in a decrease in the amount of data, or flare light that does not contribute to image formation is superimposed on the image to improve the image quality. To lower.

  According to the fifth aspect of the present invention, means for preventing crosstalk of the image by each lens block is added to the configuration, and crosstalk on the image sensor surface of light from each lens block is prevented. Thereby, the quality of the acquired image can be ensured.

  The compound eye image input device according to the present invention is used to detect a parallax of a subject in each image of the compound eye image and calculate a distance from the parallax to the subject. At this time, if the distance between the lens blocks (distance between the optical axes in a plane perpendicular to the optical axis) changes with time, the parallax of the subject in each image changes due to the change, and thus differs from the original distance. There is a possibility to calculate the measured value. Although the change in the lens block interval with time may be suppressed by increasing the rigidity of the housing that covers the camera, a material having high rigidity is expensive, and the cost of the apparatus increases.

  According to the sixth aspect of the present invention, a lens block holding member for holding each lens block as a unit is added to the configuration, and each lens block is held as a unit by the holding member instead of the camera casing. As a result, it is possible to suppress a change with time in the interval between the lens blocks, and it is not necessary to increase the overall rigidity of the camera housing, so that the apparatus can be configured at low cost. Without increasing the cost of the apparatus, it is possible to eliminate the influence of the change with time of each lens block interval on the measurement error and to obtain an accurate distance measurement value.

  The compound eye image input device according to the present invention is used to detect the parallax of the subject in each image of the compound eye image and calculate the distance from the parallax to the subject. At that time, if the position and orientation of the components of the light guide optical system corresponding to each lens block change over time, the subject's parallax in each image changes due to the change, so a measurement value different from the original distance is obtained. There is a possibility to calculate.

According to the seventh aspect of the present invention, a part of the light guiding means for each lens block of the first lens block group , for example, one mirror, is constituted by a common component. As a result, even if the position and orientation of at least the common parts change over time, the position of the subject in each image is similarly shifted and the parallax does not change, so the distance to the original subject can be accurately calculated. it can.

In the invention of claim 8, the light guiding means for each lens block of the first lens block group is constituted by an integral bending optical system. Even if there is a change over time in the light guide means, the position of the subject in each image is similarly shifted and the parallax does not change, so the distance to the original subject can be accurately calculated.

According to a ninth aspect of the present invention, there is provided the compound eye image input device according to any one of the first to eighth aspects, the compound eye image by the first lens block group captured by the compound eye image input device, and the second lens block group. A distance measuring device is configured with an arithmetic unit that calculates the distance to the subject from the parallax of the subject image in the compound-eye image, and combines the two distance calculation results to generate one distance image. Thereby, the range of distance measurement can be expanded while ensuring the resolution of distance measurement. By synthesizing and outputting the distance image obtained by the short distance measurement and the distance image obtained by the long distance measurement as one image, it is possible to output a distance image that is easy for the user to recognize.

According to a tenth aspect of the present invention, the computing unit divides a compound eye image into a number of images corresponding to lens blocks, detects a parallax between the divided images, and calculates a distance based on the detected parallax. To do.

An eleventh aspect of the present invention is the distance measuring device according to the ninth or tenth aspect , wherein the compound-eye image input device has a low MTF in which each lens block is finite (not zero) and an MTF associated with a light incident angle. The arithmetic unit performs a distance calculation operation using an image with a low MTF, and obtains an image with an improved MTF by performing an inverse filter operation on the image.

  The accuracy of the parallax detection calculation by image differentiation is improved by performing the distance calculation calculation using an image that is intentionally finite (not zero) from the low spatial frequency band to the high spatial frequency band and has a low MTF. . This realizes distance measurement with high measurement accuracy by high-speed and low-load calculation.

In the invention of claim 1, 2, instead of long intervals between lens block to ensure the resolution by increasing the focal length of each lens block and the optical path becomes longer due to the focal length, the light guiding means of the device Secure without increasing the size. In addition, the single imaging unit not only reduces the size of the apparatus, but also eliminates individual differences in sensitivity of the imaging unit and imaging timing deviation. As a result, it is possible to realize a compound eye image input device for measuring distance with high accuracy, which ensures both distance measurement resolution and miniaturization of the device, and more closely matches the characteristics and conditions of the compound eye image.

In the first and second aspects of the invention, the lens block group for measuring the distance of the subject is divided into a long distance measurement and a short distance measurement, and the long distance measurement lens block group (first lens block group) is The focal length is lengthened, and the short-distance measuring lens block group (second lens block group) is shortened in focal length to form an apparatus. As a result, distance measurement using the long-distance measurement lens block group can ensure the distance resolution of a long-distance subject, and the short-distance measurement lens block group can reduce the optical magnification. However, distance measurement can be performed without the subject image exceeding the size of the imaging surface of the imaging means. Thereby, the range of distance measurement can be expanded while ensuring the resolution of distance measurement.

  In the invention of claim 3, the lens block and the light guide means are arranged so that the image is arranged in a direction substantially perpendicular to the optical axis of the optical system constituting the light guide means within the image pickup surface of the image pickup means. To do. As a result, a decrease in the number of pixels in the horizontal direction can be prevented, and a reduction in recognition performance can be prevented in the image input device used for distance measurement.

  In the invention of claim 4, by making the longitudinal direction of the imaging surface substantially coincide with the arrangement direction of the image, a predetermined number of pixels can be secured in both the horizontal and vertical directions. Recognition performance can be ensured.

  In the invention of claim 5, by adding a means for preventing crosstalk of the image by each lens block to the configuration, it is possible to prevent crosstalk on the image pickup element surface of light from each lens block. The quality of the image acquired by this can be ensured.

  According to the sixth aspect of the present invention, the lens blocks are integrally held by a holding member provided separately instead of the camera casing. Thereby, a change with time of the interval between the lens blocks can be suppressed, and since it is not necessary to increase the overall rigidity of the camera housing, the apparatus can be configured at low cost. As a result, it is possible to obtain an accurate distance measurement value without increasing the cost of the apparatus and eliminating the influence on the measurement error of the change with time of each lens block interval.

According to the seventh aspect of the present invention, a part of the light guiding means for each lens block of the first lens block group , for example, one mirror is constituted by a common component. As a result, even if the position and orientation of at least the common parts change over time, the position of the subject in each image is similarly shifted and the parallax does not change, so the distance to the original subject can be accurately calculated. It is possible to eliminate the influence of the change in the light guiding means over time on the measurement error, and to obtain an accurate distance measurement value.

In the invention of claim 8, the light guiding means for each lens block of the first lens block group is constituted by an integral bending optical system. As a result, even if the light guiding means changes over time, the position of the subject in each image is similarly shifted and the parallax does not change, so the distance to the original subject can be accurately calculated, and the light guide It is possible to obtain an accurate distance measurement value by eliminating the influence of the change of the means over time on the measurement error.

In the ninth aspect of the invention, since the distance measuring device is configured using the compound eye image input device of the first to eighth aspects of the invention, the same effects as those of the first to eighth aspects of the invention are possible. In addition, by synthesizing and outputting the distance image based on the short distance measurement and the distance image based on the long distance image into one image, it is possible to output a distance image that is easy for the user to recognize.

In the invention of claim 10, a specific configuration of the arithmetic unit in the distance measuring device of claim 9 can be provided.

In the invention of claim 11, the parallax based on the image differentiation is performed by performing the distance calculation calculation using an image that is intentionally finite (not zero) from the low spatial frequency band to the high spatial frequency band and has a low MTF. The accuracy of the detection calculation can be improved, and thereby, distance measurement with high measurement accuracy can be realized with high speed and low load calculation.

It will be described in detail by drawings, embodiments of the present invention.

  FIG. 1 shows a device configuration of Embodiment 1 (basic configuration example) of a compound eye image input device according to the present invention. Reference numeral 1 denotes a first lens block for observing the subject from the left side and forming an image of the subject on the image plane, and is configured by stacking a plurality of lens surfaces in the optical axis direction. Similarly, reference numeral 2 denotes a second lens block for observing the subject from the right side and forming a copy image on the image plane, which is similarly configured by stacking a plurality of lens surfaces in the optical axis direction. . The lens blocks 1 and 2 have substantially the same lens configuration and optical characteristics in order to acquire subject images that differ only in parallax based on the interval between 1 and 2 in a plane substantially perpendicular to the optical axis of the lens block.

  The light beam that has passed through the lens block 1 is folded back by the mirror prism 3a, and is further folded back by the mirror prism 3b to reach the region on the almost left half of the sensor surface in the image sensor 6 as a single imaging means. Similarly, the light beam that has passed through the lens block 2 is folded back by the mirror prisms 4 a and 4 b, and reaches the almost right half region of the sensor surface of the image sensor 6. Each mirror prism 3a, 3b, 4a, 4b has a mirror surface deposited on its ridgeline, reflects light rays as shown in FIG. 1, and guides the light rays that have passed through the lens blocks 1, 2 to the image sensor 6. Acts as means 3 and 4. The image sensor 6 is a solid-state imaging device such as a CCD or a CMOS, and is mounted on the substrate 5. Reference numeral 7 denotes a housing that holds a lens block, a mirror prism, an image sensor, and a substrate. The mirror prism is bonded by bringing one of the surfaces perpendicular to the paper surface into contact with the housing.

  Although not shown, the image sensor 6 is provided with a cover glass for protecting the sensor surface and, if necessary, an optical thin film or a near infrared light that acts as a low-pass filter for preventing aliasing. An optical thin film that acts as an IR filter that eliminates the above may be provided.

  The image captured by the image sensor 6 is transferred to the computing unit 100 via the image data interface unit. The arithmetic unit 100 performs arithmetic processing for detecting the parallax of the subject in the images by the lens blocks 1 and 2, calculates the distance from the camera to the subject, and outputs the distance image. The computing unit 100 has basically the same configuration as a computer. FIG. 1 also shows a processing flow for outputting a distance image by the computing unit 100. The device configuration including the calculator 100 is referred to as a distance measuring device. The same applies to the configurations of the second and subsequent embodiments.

  FIG. 2 is an example of an image acquired when the compound-eye image input apparatus of the present embodiment is mounted on an automobile and the front is observed. The image by the lens block 1 is observed in the left half area 8a of the image sensor 6, and the image by the lens block 2 is observed in the right half area 8b by being vertically and horizontally reversed. For easy understanding, FIG. 2 shows a vertically rotated image. In the images 8a and 8b, the front scenery of the car is observed from different positions according to the distance between the lens blocks 1 and 2, and parallax occurs in the observed image. If the vertical positions and postures of the lens blocks 1 and 2 are strictly adjusted, an image having a parallax only in the horizontal direction due to the distance between the lens blocks 1 and 2 can be obtained. A black portion 9 in the vicinity of the center of the image is a shadowed area in the portion where the mirror prisms 3b and 4b are adjacent.

  The image in FIG. 2 is temporarily stored in the memory. The arithmetic unit 100 accesses the stored image data, and first cuts out the effective areas 8a and 8b in the acquired image. Then, as shown in FIG. 2, paying attention to the minute area 10a in 8a and the minute area 10b in 8b corresponding thereto, the parallax δ (0, 0) of the subject in these minute areas is calculated. For this purpose, for example, the sampling position shift estimation method described in Japanese Patent No. 3773563 is used. According to this method, the parallax can be calculated for each of the horizontal direction x and the vertical direction y of the image. However, since the parallax occurs only in the horizontal direction as described above, the parallax in the horizontal direction may be calculated here. Note that δ is obtained in pixel units (pixels) of the image sensor.

  Between the distance A from the device to the subject and the parallax δ,

の関係が成り立つ。ここで、Ｂはレンズブロック間の間隔、ｆはレンズブロックの焦点距離、ｐはイメージセンサの画素サイズである。この（１）式に視差δを代入することで、被写体距離Ａを求めることができる。

The relationship holds. Here, B is the distance between the lens blocks, f is the focal length of the lens blocks, and p is the pixel size of the image sensor. The subject distance A can be obtained by substituting the parallax δ into the equation (1).

  After that, the minute region of interest is shifted to the position 11a in FIG. 2, and the parallax δ (1, 0) is calculated with reference to 11b. Such an operation is performed on the entire image while scanning the minute area in the x and y directions in FIG. 2, parallax δ (x, y) is calculated for all the minute areas, and subject distance A ( x, y) can be determined. When the minute regions are combined, a distance image is acquired, and for example, the distance to the front car 12 and the distance to another car 13 in FIG.

  Note that FIG. 1 shows a calculation processing flow for outputting a distance image as a distance measurement result, but the distance image includes a parallax image.

  3 to 5 show a device configuration of a compound eye image input device according to a second embodiment of the present invention. The present embodiment is an example of a device configuration that enables a combination of a long distance measurement and a short distance measurement. FIG. 3 is a diagram of the apparatus observed from the optical axis direction of the lens block. 4 is a view of the apparatus observed from above, and FIG. 5 is a view of the apparatus observed from below. Basically, the compound-eye image input apparatus according to the present embodiment is configured by combining the units shown in FIGS.

  3 to 5, the components 1 to 6 are the same as those in FIG. 1, and a compound eye image by the lens blocks 1 and 2 as the first lens block group is transmitted through the light guides 3 and 4 to the image sensor 6. Obtained by Reference numerals 14 and 15 denote a pair of lens blocks which are the second lens block group, and have a short focal length compared to the lens blocks 1 and 2. The light that has passed through the lens blocks 14 and 15 is directly guided to the image sensor 6 without passing through the light guiding means. The image sensor 6 is divided into four regions, and the images of the lens blocks 14 and 15 are picked up in the upper half of the paper surface in FIG. 3, and the images of the lens blocks 1 and 2 are picked up in the lower half. Reference numerals 16 and 17 denote light shielding members for preventing crosstalk and flare light between the lens blocks.

  In the arithmetic unit 100, as shown in the processing flow in FIG. 3, the parallax of the subject is detected based on the images 1 and 2 picked up by the image sensor 6 by the lens blocks 1 and 2, and based on the previous equation (1). The distance to the subject is calculated and used as the long distance measurement result. On the other hand, the parallax of the subject is similarly detected based on the images 3 and 4 captured by the image sensor 6 using the lens blocks 14 and 15, and the distance to the subject is calculated to obtain a short distance measurement result. Then, the obtained long-distance measurement result and short-distance measurement result are combined and output as a single distance image.

  FIG. 6A shows an example of an image acquired for a long distance measurement using the lens blocks 1 and 2, and FIG. 6B shows an example of an image acquired for a short distance measurement using the lens blocks 14 and 15. Show. Here, the image is shown rotated forward for easy understanding. Since the images of the lens blocks 1 and 2 have a long focal length, the subject image appears large. On the other hand, the images of the lens blocks 14 and 15 have a short focal length, so the optical magnification is low, and the subject looks small and is observed in a wide field of view. FIG. 7 shows an example of the distance image. The distance is displayed in shades of color, and the short distance measurement result and the long distance measurement result are synthesized and output. The result of the long distance measurement corresponds to a part 18 of the distance image, and the part 18 has a narrow field of view, so that the distance resolution for a long distance object is higher than that of other regions.

  FIG. 8 shows a device configuration of a third embodiment of the compound-eye image input device according to the present invention. 8, parts having the same numbers as in FIG. 1 represent the same parts as in FIG. 1, and the overall operation is the same as in FIG. Reference numeral 9 denotes a light shielding member, which acts to prevent light or flare light that has passed through one lens block from reaching the imaging region for capturing an image by the other lens block. The light shielding portion 9 is configured so that the metal member is dyed black to prevent the passage of light and not to be reflected on the surface of the light shielding member.

  3 and 17 in FIG. 3 also act to prevent light crosstalk in the same manner as described above.

  FIG. 9 shows an apparatus configuration of a compound eye image input apparatus according to Embodiment 4 of the present invention. 7, parts having the same numbers as in FIG. 1 represent the same parts as in FIG. Reference numeral 19 denotes a mirror bonded to the housing 7. The light passing through the lens block 1 and reflected by the mirror prism 3 a is reflected by the mirror 19 and guided to the left half of the image sensor 6. Similarly, the light passing through the lens block 2 and reflected by the mirror prism 4 is reflected by the mirror 19 and guided to the right half of the image sensor 6.

  In the case of the configuration of FIG. 1, when the position and inclination of the mirror prisms 3b and 4b change independently, the position of the image on the image sensor 6 by each lens block changes independently. Since the change in the image is detected as parallax, the parallax corresponding to the distance becomes noise, and the distance measurement performance is deteriorated. On the other hand, in the configuration of FIG. 9, the mirror 19 contributes to the position on the image sensor 6 of both the image by the lens block 1 and the image by the lens block 2, so that the inclination of the mirror 19 changes over time. Even if it does, since the image by both lens blocks moves equally, the influence on the distance measurement of the inclination of the mirror 19 can be excluded.

  FIG. 10 shows an apparatus configuration of a fifth embodiment of the compound-eye image input apparatus according to the present invention. In FIG. 10, reference numeral 20 denotes a mirror block. Lights that have passed through the lens blocks 1 and 2 and reflected by the mirror prisms 3 a and 4 a are respectively reflected and guided to the image sensor 6. Similar to the mirror 19 in FIG. 9, the mirror block 20 contributes to the imaging position of the light passing through both lens blocks. Therefore, even if the position or inclination of the mirror block 20 changes with time, parallax detection and distance measurement The influence on can be eliminated.

  FIG. 11 shows an apparatus configuration of Embodiment 6 of the compound eye image input apparatus according to the present invention. In FIG. 11, 21 is an optical block having mirror surfaces 21a, 21b, 21c and 21d, and constitutes the light guide means 3 and 4 of FIG. The light that has passed through the lens block 1 is reflected by 21a and 21b and guided to the right half of the image sensor 6 to form an image. The light that has passed through the lens block 2 is reflected by 21c and 21d and is guided to the left half of the image sensor 6 to form an image. Each mirror surface is formed integrally with the block and does not tilt independently or cause a positional shift. Even if the block 21 is tilted or misaligned, the light beam that has passed through the lens block 1 and the light beam that has passed through the lens block 2 change the optical path in the same manner, so that the detected parallax is not affected. Accordingly, it is possible to suppress or eliminate the influence of the time-dependent inclination and displacement of the components constituting the light guide means 3 and 4 shown in FIG. 1 on the distance measurement.

  FIG. 12 shows a view of only the optical block 21 taken out and a cross-sectional view thereof. The optical block 21 has a configuration in which the blocks formed by 21a and 21b and the blocks formed by 21c and 21d are connected to each other with the black-filled portions in the drawing as a joint. The material is preferably a resin and can be processed efficiently by molding.

  As another mode of the optical block 21 in this embodiment, as shown in FIG. 13, the prisms 22 and 23 may be bonded via the prism 24. Such a configuration may be used in the case of manufacturing a material such as glass that is difficult to mold compared to a resin.

  FIG. 14 shows the apparatus configuration of a seventh embodiment of the compound-eye image input apparatus according to the present invention. In FIG. 14, reference numeral 25 denotes an optical block having mirror surfaces 25a and 25b. Reference numeral 26 denotes a plate for holding the lens block. It is made of a material with low thermal deformation such as ceramic or a material with high rigidity. The lens blocks 1 and 2 are fixed to the holding member 26 by bonding, the holding member 26 is fixed to the housing 7 by bonding, and 27 is a mirror and is fixed to the holding member 26 by bonding. The light passing through the lens block 1 and reflected by the mirror surface 25 a is reflected by the mirror 27 and guided to the left half of the image ship 6. Similarly, the light passing through the lens block 2 and reflected by 25 b is reflected by the mirror 27 and guided to the right half of the image sensor 6.

  Independent temporal and positional changes in the lens blocks 1 and 2 cause the parallax in the parallax image to fluctuate, and thus affect the distance measurement value based on the detected parallax. The entire housing that holds the lens blocks 1 and 2 may be made of a material that is highly resistant to thermal deformation or a material that is highly rigid. However, the cost increases and the size of the housing that has a complicated shape increases. The material cost will increase. In the present embodiment, a plate-like member having a relatively simple shape is manufactured using a material resistant to thermal deformation or a material having high rigidity as the holding member 26, thereby holding the lens blocks 1 and 2. Therefore, it is possible to suppress the time-dependent fluctuation of the independent positions and postures of the lens blocks 1 and 2 while minimizing the processing cost and the material cost, and to ensure the distance measurement performance.

  FIG. 15 shows an example in which the lens blocks 1 and 2 are held by the holding unit 26 in the embodiment of FIG. 10 to eliminate the influence of the lens block temporal variation and the light guide means temporal variation on the distance measurement. Can do. In other embodiments as well, the lens block can be held by the holding member 26 in the same manner.

  FIG. 16 shows an apparatus configuration of an eighth embodiment of the compound eye image input apparatus according to the present invention. Reference numeral 27 denotes an optical block, and mirrors are deposited on the surfaces 27a, 27b, and 27c. The optical block 27 reflects light that has passed through the lens blocks 1 and 2 and guides it to the image sensor 6, respectively. Similar to the embodiment of FIG. 11, by integrating the light guide means, it is possible to eliminate the influence of the positional deviation of the components constituting the light guide means on the distance measurement. By holding the lens blocks 1 and 2 on the holding member 26 in the same manner as in FIG. 15, it is possible to suppress temporal variations in the independent position and orientation of the lens block.

  FIG. 17 shows the apparatus configuration of a ninth embodiment of the compound-eye image input apparatus according to the present invention. FIG. 17 shows the apparatus configuration observed from the side. FIG. 18 shows a case where the apparatus configuration is observed from above. 17 and 18, the same parts as those in FIG. 1 are given the same numbers as those in FIG. The difference from the configuration of FIG. 1 is that the image guided from the lens block 1 to the image sensor 6 via the mirror prisms 3a and 3b and the image guided from the lens block 2 to the image sensor 6 via the mirror prisms 4a and 4b. Are the points arranged in a direction substantially perpendicular to the optical axis of the optical system and the point in which the longitudinal direction of the image sensor coincides with the arrangement direction of the images.

  For example, when the number of pixels of the image sensor 16 is 1280 × 1024, the size of each of the two images is 640 × 1024 in the configuration of FIG. 1, and the number of pixels in the horizontal direction of each image is halved. In an image input device mounted on an automobile, there is a demand to use an image having the device configuration of FIG. 1 for distance measurement and at the same time to use it as an image for recognition such as a sign or a white line. Is required, and the number of pixels of 640 may be insufficient. 17, the image from the lens block 1 is guided to the upper half of the image sensor 6 and the image from the lens block 2 is guided to the lower half of the image sensor 6, as shown in FIG. As a result, the image size of each of the two images is 1024 × 640, the number of pixels in the horizontal direction can be ensured, and the case where the resolution is required in the horizontal direction can also be handled.

  FIG. 19 shows an example of a compound eye image in which images from the respective lens blocks are arranged in a direction (vertical direction) substantially perpendicular to the optical axis of the optical system constituting the light guide means. 8a is an image by the lens block 1 and 8b is an image by the lens block 2, and the image is shown rotated forward for easy understanding. As shown in the processing flow in FIG. 17, the computing unit 100 detects parallax using these images, obtains a distance image, and recognizes a sign or the like by recognition processing.

  In FIG. 17 and FIG. 18, the longitudinal direction of the image sensor and the image arrangement direction are made to coincide, but the short direction of the image sensor and the image arrangement direction may be made to coincide. In that case, in the above-described example, the image size of each of the two images is 1280 × 512, and the horizontal resolution can be further increased. The horizontal and vertical orientation of the image captured by the image sensor (whether the longitudinal direction of the sensor is the horizontal direction or the vertical direction) can be easily set by a register.

  Further, as shown in FIG. 20, when the mirror surfaces 3a, 3b and 4a, 4b are integrated, the influence of the position variation and the posture variation of the light guide means 3, 4 on the distance measurement is affected. Even if the light guide means 3 and 4 are integrated by resin molding or bonded and integrated, the influence of fluctuation over time can be further eliminated.

  In the first and ninth embodiments, it is assumed that the size of the image obtained by each lens block is equal, but one image size may be larger than the other. For example, when the number of pixels of the image sensor is 1280 × 1024 pixels, in the device configuration of the first embodiment, one is 800 × 1024 pixels and the other is 480 × 1024 pixels, or in the device configuration of the ninth embodiment, one is 1024. It may be × 720 pixels and the other may be 1024 × 560 pixels. In these cases, a distance image can be obtained only with a size corresponding to the smaller image size, but it is advantageous in that recognition processing can be executed with a relatively high resolution as necessary with the larger image size.

  FIG. 21 shows an example of the MTF characteristics of the lens block. FIG. 21A shows a state in which the incident angle of the light beam to the lens block with respect to the optical axis is different from A, B, and C. FIG. 21B shows tangential and sagittal directions corresponding to A, B, and C. The MTF is shown. By adjusting the surface curvature and the surface interval of each lens constituting the lens block, the MTF characteristic is set low from a low spatial frequency to a high spatial frequency, and thereby the difference in the MTF characteristic with the light incident angle to the lens block is set. Can be suppressed.

  When an image acquired by a lens block having an MTF characteristic as shown in FIG. 21 is estimated by simulation, the image is as shown in FIG. 23A, and the contrast is low and the low image is uniform throughout the image.

  In the method shown in the patent rear of the previous patent No. 3773503, it is possible to perform parallax detection at high speed and low load by performing differential calculation of an image having parallax, but high spatial frequency characteristics, that is, When the parallax detection calculation is performed from an image having a relatively rapid luminance change, there is a characteristic that noise is included in the detected value.

  FIG. 22 shows an example of a parallax detection simulation for showing the relationship between the spatial frequency and the parallax detection error. In the figure, the horizontal axis represents image blur (Gaussian function standard deviation), and the vertical axis represents detected parallax (average and standard deviation). From the figure, it can be seen that as the blur increases, the average value of the detected parallax approaches the true value (in this case, 0.6 pixel), and the variation also decreases.

  In this embodiment, the distance calculation calculation is performed using an image in which the MTF is intentionally finite (not zero) from the low spatial frequency band to the high spatial frequency band as shown in FIG. Thus, the above-described parallax detection error is suppressed. Since the MTF of the lens block is not zero, when contrast is required for recognizing a sign or a white line, the image of FIG. 23A is spatially filtered based on the PSF estimated from the design data of the lens block. Thus, an image with improved contrast is restored as shown in FIG.

The block diagram of Example 1 (basic structure example) of the compound-eye image input device by this invention. FIG. 3 is a diagram illustrating a state of a compound eye image acquired using the apparatus according to the first embodiment. The figure observed from the optical axis direction of a lens block with the apparatus structure of Example 2 of the compound-eye image input device by this invention. The figure which made the observation direction of the apparatus of Example 2 from the upper direction. The figure which made the observation direction of the apparatus of Example 2 from the downward direction. FIG. 6 is a diagram illustrating a state of a compound eye image acquired using the apparatus according to the second embodiment. The figure which shows the example of the distance image which synthesize | combined the long-distance measurement result obtained with the apparatus of Example 2, and the short-distance measurement result. The block diagram of Example 3 of the compound-eye image input device by this invention. The block diagram of Example 4 of the compound-eye image input device by this invention. The block diagram of Example 5 of the compound-eye image input device by this invention. The block diagram of Example 6 of the compound-eye image input device by this invention. The figure which took out and showed the optical block of the apparatus of FIG. The figure which shows the other structural example of an optical block. The block diagram of Example 7 of the compound-eye image input device by this invention. The figure which applied Example 7 to the apparatus of FIG. The block diagram of Example 8 of the compound-eye image input device by this invention. The block diagram of Example 9 of the compound-eye image input device by this invention. The figure which observed the apparatus structure of FIG. 17 from upper direction. FIG. 10 is a diagram illustrating a state of a compound eye image acquired using the apparatus according to the ninth embodiment. Another block diagram of Embodiment 9 of the compound eye image input device by this invention. The figure explaining the example of a finite and low MTF characteristic irrespective of the incident angle of a light ray. The figure explaining the relationship between the blur condition of an image, and parallax detection performance. The figure which shows the example of the image which restored the contrast with the image obtained by the optical system which has a finite and low MTF characteristic irrespective of the incident angle of a light ray, and a spatial filter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Lens block 3, 4 Light guide means 5 Board | substrate 6 Image sensor 7 Case 100 Calculator

Claims (11)

A compound eye image input device for measuring a distance from an object using parallax by a compound eye,
A first lens block group composed of two or more lens blocks having a predetermined focal length and installed in a plane substantially perpendicular to the optical axis;
A second lens block group composed of two or more lens blocks having a focal length shorter than that of the lens blocks in the first lens block group and disposed in a plane substantially perpendicular to the optical axis;
A single imaging means for capturing an image of each lens block group as a compound eye image on the same plane;
A compound-eye image input device comprising: a light guide unit that folds back an image of each lens block of the first lens block group and guides the image to the imaging unit. The lens blocks constituting the first lens block group are installed at a predetermined interval from each other,
The compound-eye image input apparatus according to claim 1, wherein the lens blocks constituting the second lens block group are disposed with an interval shorter than the predetermined interval. In the imaging plane of the imaging means, in a direction substantially perpendicular to the optical axis of the optical system constituting the light guiding means that, as the image is arranged, and arranging the respective lens blocks and said guiding means The compound-eye image input device according to claim 1, wherein The compound-eye image input apparatus according to claim 3, wherein a longitudinal direction of an imaging surface is substantially matched with an arrangement direction of the images. 5. The compound-eye image input apparatus according to claim 1, further comprising a member that prevents crosstalk of light beams that pass through each of the lens blocks. 6. The compound-eye image input device according to claim 1, further comprising a lens block holding member for holding the lens blocks integrally. 7. The compound-eye image input apparatus according to claim 1, further comprising a unit configured to share a part of the light guide unit with respect to each lens block of the first lens block group . 8. 7. The compound-eye image input apparatus according to claim 1 , wherein a light guide unit for each lens block of the first lens block group is configured by an integral bending optical system. The parallax of the subject image in the compound-eye image input device according to any one of claims 1 to 8, and a compound-eye image captured by the compound-eye image input device and a compound-eye image captured by the first lens block group and the second lens block group. A distance measuring apparatus comprising: an arithmetic unit that calculates a distance from a subject to a subject and combines the two distance calculation results to generate one distance image. The computing unit divides a compound eye image into a number of images corresponding to lens blocks, detects a parallax between the divided images, and calculates a distance based on the detected parallax. Item 10. The distance measuring device according to Item 9. The distance measuring device according to claim 9 or 10,
The compound-eye image input device has a characteristic that each lens block is finite (non-zero), has a low MTF, and has a small difference in MTF with a light incident angle.
The computing unit performs a distance calculation calculation using an image with a low MTF, and obtains an image with improved MTF by performing an inverse filter operation on the image.
A distance measuring device characterized by that.

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