JP2023019651A - Projection device and distance measuring system - Google Patents

Abstract

Kind Code: A1 A reduction in brightness of a pattern projected onto an object can be suppressed while expanding a range in which the pattern projected onto the object maintains a contrast ratio that can be used as a feature point for distance measurement. A projection device and a ranging system are provided. A projection device (1) includes a first pattern plate (11a) having a first pattern, a second pattern plate (11b) having a second pattern, and the first pattern plate (11a) and the second pattern plate (11b). The light source 12 for irradiating light onto the object and the first pattern plate 11a and the second pattern plate 11b are collected by condensing the light transmitted through the first pattern plate 11a and second pattern plate 11b. and a projection optical system 13 for projecting onto 200 . The first pattern plate 11 a and the second pattern plate 11 b are provided on the optical axis OA of the projection optical system 13 and between the light source 12 and the projection optical system 13 . [Selection drawing] Fig. 3

Description

The present invention relates generally to a projection device for projecting a pattern onto an object and a ranging system including the projection device, and more particularly to a first pattern and a first pattern imaged at different positions onto the object. The present invention relates to a projection device for projecting two patterns and a ranging system including the projection device.

2. Description of the Related Art Conventionally, ranging devices that measure the distance to an object by capturing an image of the object have been widely used. Such a distance measuring device includes an imaging optical system for condensing light from an object and forming an optical image of the object, and converting the optical image of the object formed by the imaging optical system into an image. A stereo camera-type distance measuring device is known that includes at least two pairs of imaging elements for performing the measurement (see, for example, Patent Document 1).

A stereo camera type distance measuring device such as that disclosed in Patent Document 1 measures two optical images corresponding to each other, which are formed by two imaging optical systems that are arranged to be mutually shifted in a direction perpendicular to the optical axis direction. The parallax between the feature points is calculated, and the distance to the feature point of the object can be calculated based on the value of this parallax. Further, depth information (three-dimensional information) of the object can be generated by calculating distances to a plurality of feature points of the object.

As feature points used when calculating parallax, parts that are easy to distinguish from other parts such as edges and patterns (also called textures) and that are easy to detect are used. In other words, in order to calculate the distance to an object using a stereo camera type distance measuring device, it is necessary to have a part that can be used as a feature point such as an edge part or a pattern on the object. There is Therefore, when there are few or no parts (edges, patterns, etc.) that can be used as feature points on the surface of the object, such as when the surface of the object is a smooth curved surface without unevenness, parallax Therefore, it has been difficult to measure the distance to the object and accurately acquire the three-dimensional shape of the object.

In order to solve such problems, a pattern plate (also called a reticle plate) having a predetermined pattern (for example, a dot pattern or a grid pattern), a light source for irradiating the pattern plate with light, and light transmitted through the pattern plate. and projection optics for projecting a pattern onto an object by focusing the light from the projection device is commonly used. A pattern is projected onto an object by a projection device, and the pattern projected onto the object is used as feature points for calculating parallax. As a result, even if there are no or few parts that can be used as feature points on the surface of the object, the distance to the object can be measured based on the parallax, and the depth information of the object can be obtained accurately. can be obtained.

When a pattern is projected onto an object using a projection optical system, a projection optical system with a long focal length (that is, a wide angle of view) is used in order to project the pattern over the widest possible range of the object. Also, in order to increase the brightness of the pattern projected onto the object, it is preferable that the F-number of the projection optical system is small. However, when a projection optical system with a long focal length and a small F-number (that is, a bright one) is used, the depth of field (DoF) that allows a predetermined pattern to be projected to maintain an acceptable focus state. of Field) becomes very shallow. If the target is outside the depth of field of the projection optics, the pattern projected onto the target will be defocused, maintaining a contrast ratio that allows the pattern to be used as a feature point for ranging. Therefore, the pattern projected onto the object cannot be used as feature points for distance measurement. As a result, the measurable range of the object becomes extremely narrow.

In response to such problems, Patent Document 2 discloses a projection device 500 as shown in FIG. As shown in FIG. 1, the projection device 500 includes a projection optical system 510, a plurality of pattern plates 520a, 520b, and 520c arranged such that the optical path lengths from the projection optical system 510 are different from each other, and the projection optical system 510. two half mirrors 530a, 530b arranged on the optical axis of 510; Transmitted light emitted from a first light source (not shown) and transmitted through the first pattern plate 520a is transmitted through the two half mirrors 530a and 530b, condensed by the projection optical system 510, and projected onto the first focal plane 540a. to form an image. Transmitted light emitted from a second light source (not shown) and transmitted through the second pattern plate 520b is reflected by the first half mirror 530a, then transmitted through the second half mirror 530b, and projected by the projection optical system 510. It is collected and imaged at the second focal plane 540b. Transmitted light emitted from a third light source (not shown) and transmitted through the third pattern plate 520c is reflected by the second half mirror 530b, collected by the projection optical system 510, and projected onto the third focal plane 540c. form an image. With such a configuration, the range in which the pattern projected onto the object maintains a contrast ratio that can be used as feature points for distance measurement is extended, and the distance measurement range of the object is extended. .

However, in the case of the configuration shown in FIG. 1, assuming that the light reflectance of the two half mirrors 530a and 530b is 80% and the light transmittance is 20%, the first pattern plate 520a The light amount of the transmitted light that has passed through is reduced to 4% by the time it reaches the projection optical system 510 (1×0.2×0.2=0.04). Similarly, the amount of light transmitted through the second pattern plate 520b decreases to 16% (1×0.8×0.2=0.16) before reaching the projection optical system 510, The amount of light transmitted through the pattern plate 520c of No. 3 is reduced to 80% before reaching the projection optical system 510 (1×0.8=0.8). As a result, the brightness of the optical image of the pattern imaged on each of the focal planes 540a, 540b, 540c is reduced, particularly the optical image of the pattern imaged on the first and second focal planes 540a, 540b. There is a problem that the brightness of the image is remarkably lowered. Therefore, in the configuration shown in FIG. 1, the range in which the pattern projected onto the object maintains a contrast ratio that can be used as a feature point for distance measurement is expanded, and the pattern projected onto the object is expanded. It was not possible to satisfy the need to suppress the decrease in brightness.

JP 2012-26841 A JP-A-7-218232

SUMMARY OF THE INVENTION The present invention has been made in view of the conventional problems described above, and an object of the present invention is to extend the range in which a pattern projected onto an object maintains a contrast ratio that can be used as a feature point for distance measurement. It is also an object of the present invention to provide a projection device capable of suppressing a decrease in brightness of a pattern projected onto an object, and a distance measurement system including the device.

Such objects are achieved by the present invention defined by the following (1) to (2).

(1) a first pattern plate having a first pattern;
a second pattern plate having a second pattern;
a light source for irradiating the first pattern plate and the second pattern plate with light;
projection for projecting the first pattern and the second pattern onto an object by condensing the transmitted light irradiated by the light source and transmitted through the first pattern plate and the second pattern; an optical system;
A projection device, wherein the first pattern plate and the second pattern plate are provided on the optical axis of the projection optical system and between the light source and the projection optical system.

(2) the projection device according to (1) above;
a ranging device configured to measure a distance to the object by imaging the object onto which the first pattern and the second pattern are projected. distance system.

In the projection device of the present invention, the first pattern plate having the first pattern and the second pattern plate having the second pattern are on the optical axis of the projection optical system, and are arranged between the light source and the projection optical system. is set between Therefore, the first pattern and the second pattern having different imaging positions can be projected onto the object. Furthermore, since the first pattern plate and the second pattern plate have high light transmittance with respect to the light emitted from the light source, the brightness of the first pattern and the second pattern projected onto the object is Decrease can be suppressed. As a result, the projection device of the present invention extends the range in which at least one of the first pattern or the second pattern projected onto the object maintains a contrast ratio that can be used as feature points for ranging. while suppressing a decrease in luminance of the pattern projected onto the object.

1 is a schematic diagram of a conventional projection device; FIG. 1 is a schematic diagram showing a ranging system according to an embodiment of the invention; FIG. 3 is a schematic diagram showing the configuration of the projection device shown in FIG. 2; FIG. FIG. 4 is a diagram showing examples of a first pattern and a second pattern; Fig. 2 shows a transparent structure that can be used in place of the first pattern plate and the second pattern plate; 7 is a graph showing an example of change in contrast ratio between the optical image of the first pattern and the optical image of the second pattern according to the projection distance; 3 is a schematic diagram showing the configuration of the ranging device shown in FIG. 2; FIG. 8 is a block diagram of an arithmetic unit shown in FIG. 7; FIG. Figure 3 is a flow chart of a ranging method performed by the ranging system shown in Figure 2;

A projection device and a ranging system according to embodiments of the present invention will now be described in detail with reference to FIGS. Identical or corresponding elements are provided with the same reference numerals in each figure. FIG. 2 is a schematic diagram showing a ranging system according to an embodiment of the invention. 3 is a schematic diagram showing the configuration of the projection device shown in FIG. 2. FIG. FIG. 4 is a diagram showing examples of the first pattern and the second pattern. FIG. 5 shows a transparent structure that can be used in place of the first pattern plate and the second pattern plate. FIG. 6 is a graph showing an example of change in contrast ratio between the optical image of the first pattern and the optical image of the second pattern according to the projection distance. 7 is a schematic diagram showing the configuration of the ranging device shown in FIG. 2. FIG. 8 is a block diagram of the arithmetic unit shown in FIG. 7. FIG. FIG. 9 is a flowchart of a ranging method performed by the ranging system shown in FIG.

A distance measuring system 100 of the present invention shown in FIG. a ranging device 2 configured to calculate the distance to the object 200 by imaging the object 200 onto which the two patterns are projected. The distance measuring device 2 is a stereo camera type distance measuring device including two imaging systems IS1 and IS2 (see FIG. 7), and obtains a first image and a second image by imaging an object 200. , is configured to calculate the distance to the object 200 based on the parallax between the first image and the second image. A first image and a second image are obtained by imaging the object 200 with the distance measuring device 2 while the projection device 1 projects the first pattern and the second pattern onto the object 200 . , the distance to the object 200 is calculated based on the parallax between the first image and the second image. Note that the type of the target object 200 is not particularly limited, and the target object 200 is any type of object that can be the target of distance measurement, such as electronic components, structures, buildings, topography, people, and animals.

FIG. 3 schematically shows the configuration of the projection device 1. As shown in FIG. As shown in FIG. 3, the projection device 1 comprises a first pattern plate 11a with a first pattern, a second pattern plate 11b with a second pattern, a first pattern plate 11a and a A light source 12 that irradiates light (typically, white light) onto the second pattern plate 11b, and transmitted light emitted by the light source 12 and transmitted through the first pattern plate 11a and the second pattern plate 11b. and projection optics 13 for projecting the first pattern and the second pattern onto the object 200 by focusing the .

The first pattern plate 11a is one or both of transparent plates made of a transparent material such as transparent glass having a high light transmittance (for example, a light transmittance of 80% or more) with respect to the light emitted from the light source 12. It is obtained by printing or baking an opaque material such as a colorant or pigment on the surface of the substrate to form a first pattern. Similarly, the second pattern plate 11b is a transparent plate made of a transparent material such as transparent glass having a high light transmittance (for example, a light transmittance of 80% or more) with respect to the light emitted from the light source 12. It is obtained by printing or baking an opaque material such as a colorant or pigment on one or both surfaces to form a second pattern. Therefore, each of the first pattern plate 11a and the second pattern plate 11b has, on one or both surfaces thereof, a transmissive portion that transmits the light from the light source 12 and an opaque portion that blocks the light from the light source 12. and The first pattern plate 11a is a positive pattern plate in which the opaque portions on one or both surfaces form the first pattern. Similarly, the second pattern plate 11b is a positive pattern plate in which opaque portions on one or both surfaces form a second pattern. The projection optical system 13 forms an optical image of the first pattern on the first focal plane FP1, and forms an optical image of the second pattern on the second focal plane FP2.

Each of the first pattern of the first pattern plate 11a and the second pattern of the second pattern plate 11b is not particularly limited as long as it is a pattern having a high contrast ratio. A random dot pattern 3 as shown in FIG. 4B or a random grid pattern 4 as shown in FIG. 4B. The random dot pattern 3 is composed of a plurality of randomly arranged dots 31 . All the dots 31 of the random dot pattern 3 have the same size. The random lattice pattern 4 is composed of a plurality of randomly extending lattice lines 41 and a plurality of intersection points (lattice points) 42 of the plurality of lattice lines 41 . All the grid lines 41 of the random grid pattern 4 have the same thickness. Furthermore, the extending direction of each grid line 41 randomly changes each time each grid line 41 passes through the intersection point 42 .

The first pattern and the second pattern are patterns of the same type. For example, if the first pattern is the random dot pattern 3, the second pattern is also the random dot pattern 3. Similarly, if the first pattern is a random grid pattern 4, then the second pattern is also a random grid pattern 4. FIG. Although the first pattern and the second pattern are of the same type as described above, the pattern characteristics of the first pattern and the pattern characteristics of the second pattern may be different from each other. The "pattern characteristics" referred to here are the size and average density of the plurality of dots 31 in the case of the random dot pattern 3, and the thickness of the plurality of grid lines 41 and the number of intersections 42 in the case of the random grid pattern 4. is the average density. In the following description, the size of the plurality of dots 31 or the thickness of the grid lines 41 is referred to as "pattern size", and the average density of the plurality of dots 31 or the average density of the plurality of intersections (grid points) 42 is referred to as the "pattern size." called density.

Returning to FIG. 3, both the first pattern plate 11a and the second pattern plate 11b are provided between the light source 12 and the projection optical system 13 and on the optical axis OA of the projection optical system 13. . The first pattern plate 11a is positioned on the optical axis OA of the projection optical system 13 closer to the light source than the second pattern plate 11b. The second pattern plate 11b is located on the optical axis OA of the projection optical system 13 and is spaced apart by a distance D from the first pattern plate 11a toward the projection optical system 13 side. Also, the second pattern plate 11 b is positioned apart from the rear principal point of the projection optical system 13 by a distance greater than the focal length of the projection optical system 13 .

The distance D between the first pattern plate 11a and the second pattern plate 11b can be set arbitrarily. Preferably, a first focusing plane FP1 on which the optical image of the first pattern is formed in focus, and a second focusing plane on which the optical image of the second pattern is formed in focus. In the entire range R between FP2, at least one of the optical image of the first pattern and the optical image of the second pattern maintains a contrast ratio that can be used as a feature point for ranging. A distance D between the first pattern plate 11a and the second pattern plate 11b is set. With such a configuration, when the object 200 is positioned within the range R between the first focal plane FP1 and the second focal plane FP2, the distance measurement can be reliably performed on the object 200. Either the first pattern or the second pattern can be projected while maintaining a contrast ratio that can be used as feature points for .

In the embodiment shown in FIG. 3, the first pattern plate 11a and the second pattern plate 11b, which are separate members, are arranged on the optical axis OA of the projection optical system 13, and the light source 12 and the projection optical system 13 and are spaced apart from each other by a distance D, it is possible to project the first pattern and the second pattern whose imaging positions are different from each other on the object 200. However, according to the present invention, It is not limited to this. For example, by providing a transparent structure 14 as shown in FIG. 5 between the light source 12 and the projection optical system 13 on the optical axis OA of the projection optical system 13, , it may be possible to project the first pattern and the second pattern with different imaging positions.

The transparent structure 14 has a pair of opposing surfaces made of a transparent material such as transparent glass having a high light transmittance (for example, a light transmittance of 80% or more) with respect to the light emitted from the light source 12. It is a struct. A first pattern is formed on one surface of the transparent structure 14 by printing or baking an opaque material such as a colorant or pigment, and one surface of the transparent structure 14 serves as a first pattern plate 11a. function as Furthermore, a second pattern is formed on the other side of the transparent structure 14 by printing or baking an opaque material such as a colorant or pigment, and the other side of the transparent structure 14 is the second pattern. It functions as a plate 11b. Also, the distance D between the pair of opposing surfaces of the transparent structure 14 is equal to the distance D between the first pattern plate 11a and the second pattern plate 11b. The transparent structure 14 has one surface functioning as the first pattern plate 11 a facing the light source 12 and the other surface functioning as the second pattern plate 11 b facing the projection optical system 13 . It is provided on the optical axis OA of 13 and between the light source 12 and the projection optical system 13 . An aspect using such a transparent structure 14 is also within the scope of the present invention.

Returning to FIG. 3, the light source 12 has a function of irradiating the first pattern plate 11a and the second pattern plate 11b with diffused light. The diffused light emitted from the light source 12 to the first pattern plate 11a and the second pattern plate 11b is visible light such as white light or monochromatic light (red light, green light, blue light, etc.), or infrared light or light. Invisible light such as ultraviolet light. Typically, light source 12 is a white LED. To simplify the explanation, the following explanation is provided assuming that the light emitted from the light source 12 is white light unless otherwise specified. The light source 12 is configured to irradiate the first pattern plate 11a and the second pattern plate 11b with diffused light substantially uniformly.

The projection optical system 13 is irradiated by the light source 12 and collects the transmitted light that has passed through the first pattern plate 11a and the second pattern plate 11b, thereby projecting the first pattern and the second pattern as objects. It has a function of projecting onto the object 200 . The projection optical system 13 is a fixed focus optical system composed of optical elements such as one or more lenses and a diaphragm. Moreover, it is preferable that the chromatic aberration of the projection optical system 13 is sufficiently corrected by a combination of a plurality of lenses. As a result, when the light source 12 emits white diffused light, the projection optical system 13 collects the transmitted light that has passed through the first pattern plate 11a and the second pattern plate 11b, thereby producing an image of the object with a high contrast ratio. A first pattern and a second pattern can be projected onto the object 200 .

The projection optical system 13 forms an optical image of the first pattern on the first focal plane FP1, and further forms an optical image of the second pattern on the second focal plane FP2. Here, the distance b1 from the rear principal point of the projection optical system 13 to the first pattern plate 11a and the distance _b2 from the rear principal point _of the projection optical system 13 to the second pattern plate 11b is represented by the following formula (1) from the lens formula.

Here, f is the focal length of the projection optical system 13, _a1 is the distance from the front principal point of the projection optical system 13 to the first focal plane FP1, and _a2 is the front principal point of the projection optical system 13. to the second focal plane FP2.

Thus, in the projection device 1 of the present invention, the first pattern plate 11a and the second pattern plate 11b are separated from each other in the optical axis direction of the projection optical system 13 on the optical axis OA of the projection optical system 13. Since they are arranged in a state shifted by D, the first focal plane FP1 on which the optical image of the first pattern is formed and the second focal plane FP1 on which the optical image of the second pattern is formed. FP2 does not match.

6, the distance a1 from the front principal point of the projection optical system 13 to the first focal plane FP1 is 450 mm, and the distance _a2 from the front principal point of the projection optical system 13 to the second focal plane FP2 _{is 450 mm} . of the optical image of the first pattern and the optical image of the second pattern according to the projection distance (distance from the front principal point of the projection optical system 13) when the projection device 1 is configured so that is 700 mm An example of change in contrast ratio is shown.

As is clear from FIG. 6, the contrast ratio of the optical image of the first pattern maintains a high value in the range of around 450 mm, which is the imaging position of the optical image of the first pattern. maintains a high value in the range of about 700 mm, which is the imaging position of the optical image of the second pattern. Assume that the first pattern or the second pattern projected onto the object 200 has a contrast ratio of 30%, which makes it available as feature points for ranging. When only the first pattern is projected onto the object 200, the contrast ratio of the optical image of the first pattern is 30% or less at a projection distance of approximately 300 mm or less and a projection distance of approximately 800 mm or more. It becomes impossible to use the obtained first pattern as a feature point for distance measurement. In this case, the measurable range of the distance measuring device 2 is limited to approximately 300 mm to approximately 800 mm. On the other hand, when only the second pattern is projected onto the object 200, the contrast ratio of the optical image of the second pattern is 30% or less at a projection distance of approximately 400 mm or less, and the second pattern projected onto the object 200 is Patterns cannot be used as feature points for ranging. In this case, the measurable range of the distance measuring device 2 is limited to approximately 400 mm or more.

On the other hand, the projection device 1 of the present invention projects onto the object 200 both the first pattern and the second pattern whose imaging positions are different from each other. A projection distance at which at least one of the first pattern and the second pattern maintains a contrast ratio of 30% or more is about 300 mm or more. Therefore, by using both the first pattern and the second pattern with different imaging positions as feature points for distance measurement, the distance measurement range of the distance measurement device 2 can be expanded.

As described above, in the projection device 1 of the present invention, the range in which the optical image of the first pattern maintains a contrast ratio that can be used as a feature point for distance measurement, and the optical image of the second pattern is the range in which the optical image of the second pattern is used for distance measurement. The range that maintains the contrast ratio that can be used as a feature point for . Since the ranging device 2 can use either the first pattern or the second pattern projected onto the object 200 as feature points for ranging, the projection device 1 can be used to measure the object By projecting onto 200 the first pattern and the second pattern with different imaging positions, the range of distance measurement device 2 can be expanded.

Further, as described above, each of the first pattern plate 11a and the second pattern plate 11b is of a positive type with opaque portions on one or both surfaces forming the first pattern or the second pattern. pattern board. Therefore, depending on the pattern size and pattern density of the first pattern or the second pattern, each of the first pattern plate 11a and the second pattern plate 11b is sensitive to the light (white light) emitted from the light source 12. On the other hand, it has a high light transmittance of about 70% or more. Therefore, by condensing the transmitted light transmitted through the first pattern plate 11a by the projection optical system 13, the luminance of the first pattern imaged on the first focal plane FP1 and the second pattern plate 11b are By condensing the transmitted transmitted light by the projection optical system 13, it is possible to greatly suppress a decrease in luminance of the second pattern imaged on the second focal plane FP2.

Further, in the projection device 1 of the present invention, the first focal plane FP1 on which the optical image of the first pattern is formed and the second focal plane FP2 on which the optical image of the second pattern is formed. do not match, the magnification _m1 of the optical image of the first pattern formed on the first focal plane FP1 is the magnification of the optical image of the second pattern formed on the second focal plane FP2. It is different from the magnification _m2 .

Specifically, the magnification _m1 of the optical image of the first pattern formed on the first focal plane FP1 and the magnification of the optical image of the second pattern formed on the second focal plane FP2 _m2 is represented by the following formula (2).

Thus, the magnification m1 of the optical image of the first pattern formed on the first focal plane FP1 _and the magnification m of the optical image of the second pattern formed on the second focal plane FP2 ₂ is different. Usually, the relationship m ₂ >m ₁ holds. Therefore, the pattern density of the optical image of the second pattern formed on the second focal plane FP2 is lower than the pattern density of the optical image of the first pattern formed on the first focal plane FP1. The pattern size of the optical image of the second pattern formed on the second focal plane FP2 is larger than the pattern size of the optical image of the first pattern formed on the first focal plane FP1. growing. Thus, the pattern characteristics (pattern size and pattern density) of the first pattern formed on the first pattern plate 11a and the pattern characteristics of the second pattern formed on the second pattern plate 11b are the same. In some cases, the pattern characteristics of the optical image of the first pattern imaged on the first focal plane FP1 are the pattern characteristics of the optical image of the second pattern imaged on the second focal plane FP2. becomes different.

In one aspect of the projection device 1 of the present invention, the pattern size of the optical image of the first pattern imaged on the first focal plane FP1 and the second pattern imaged on the second focal plane FP2 are The first pattern of the first pattern plate 11a and the second pattern of the second pattern plate 11b may be configured such that the pattern size of the optical image of the pattern is the same.

Specifically, the size of each dot 31 of the first pattern formed on the first pattern plate 11a (when each of the first pattern and the second pattern is the random dot pattern 3) or each grid The thickness of the line 41 (when each of the first pattern and the second pattern is the random lattice pattern 4) is assumed to be PS ₁ , and each dot 31 of the second pattern formed on the second pattern plate 11b or the thickness of each grid line ₄₁ is _PS2 , the _first pattern of the first pattern plate 11a _and the _second A second pattern is formed on the pattern plate 11b. In this case, since the relationship of m ₂ >m ₁ is usually established, the relationship of PS ₁ >PS ₂ is established. That is, the pattern size _PS1 of the first pattern on the first pattern plate 11a is larger than the pattern size _PS2 of the second pattern on the second pattern plate 11b. With this configuration, the pattern size of the optical image of the first pattern formed on the first focal plane FP1 and the pattern of the optical image of the second pattern formed on the second focal plane FP2 can be equal in size.

In another aspect of the projection device 1 of the present invention, the pattern density of the optical image of the first pattern imaged on the first focal plane FP1 and the optical image of the first pattern imaged on the second focal plane FP2 The first pattern of the first pattern plate 11a and the second pattern of the second pattern plate 11b may be configured such that the pattern densities of the optical images of the two patterns are equal.

Specifically, the average density of the plurality of dots 31 of the first pattern formed on the first pattern plate 11a (when each of the first pattern and the second pattern is the random dot pattern 3) or Let PD ₁ be the average density of the plurality of intersections 42 (when each of the first pattern and the second pattern is the random lattice pattern 4), and the number of the second patterns formed on the second pattern plate 11b When the average density of the dots 31 or the average density of the plurality of intersections 42 is PD ₂ , the first pattern of the first pattern plate 11 a satisfies the condition of PD ₁ ×m ₂ =PD ₂ ×m ₁ and the second pattern of the second pattern plate 11b. In this case, since the relationship of m ₂ >m ₁ is normally established, the relationship of PD ₁ <PD ₂ is established. That is, the pattern density _PD1 of the first pattern on the first pattern plate 11a is lower than the pattern density _PD2 of the second pattern on the second pattern plate 11b. With such a configuration, the pattern density of the optical image of the first pattern formed on the first focal plane FP1 and the pattern of the optical image of the second pattern formed on the second focal plane FP2 are densities can be equal.

Also, in another aspect of the projection device 1 of the present invention, the pattern size and pattern density of the optical image of the first pattern imaged on the first focal plane FP1 and the pattern density of the optical image of the first pattern formed on the second focal plane FP2 are the same. The first pattern on the first pattern plate 11a and the second pattern on the second pattern plate 11b are configured such that the pattern size and the pattern density of the optical image of the imaged second pattern are equal. may have been

Thus, in the projection device 1 of the present invention, the pattern characteristics of the first pattern formed on the first pattern plate 11a and the pattern characteristics of the second pattern formed on the second pattern plate 11b are may be different from each other. In particular, the pattern size and pattern density of the optical image of the first pattern imaged on the first focal plane FP1 and the pattern of the optical image of the second pattern imaged on the second focal plane FP2 It is preferable that the first pattern of the first pattern plate 11a and the second pattern of the second pattern plate 11b are configured such that the size and the pattern density are equal.

With such a configuration, the pattern characteristics of the first pattern projected onto the object 200 positioned within the range R between the first focal plane FP1 and the second focal plane FP2 and the pattern characteristics of the second pattern are projected. pattern characteristics can be approximately equal. Therefore, even when the ranging device 2 uses the first pattern projected onto the object 200 located within the range R as feature points for ranging, the object located within the range R Even when the second pattern projected onto the object 200 is used as a feature point for distance measurement, the distance information of the object 200 is obtained with the resolution necessary to generate the depth information of the object 200. can do. Furthermore, even when the ranging device 2 uses the first pattern projected onto the object 200 located within the range R as feature points for ranging, the object located within the range R Even when the second pattern projected onto the object 200 is used as a feature point for distance measurement, there is no difference in the resolution of the acquired distance information of the object 200. Therefore, each point of the object 200 It is possible to suppress a change in the accuracy of the generated depth information of the object 200 according to the depth position of the object 200 .

Thus, the pattern characteristics (pattern size PS ₁ and pattern density PD ₁ ) of the first pattern formed on the first pattern plate 11a and the pattern of the second pattern formed on the second pattern plate 11b The characteristics (pattern size PS ₂ and pattern density PD ₂ ) can be set arbitrarily. By appropriately setting the pattern characteristics of the first pattern formed on the first pattern plate 11a and the pattern characteristics of the second pattern formed on the second pattern plate 11b, the front side of the projection optical system 13 The pattern density of the first pattern projected onto the object 200 and the pattern density of the second pattern occurring when the distance from the principal point to the object 200 onto which the first pattern and the second pattern are projected increases. It is possible to prevent extreme reduction in the pattern density of the patterns and excessive enlargement of the pattern size of the first pattern and the pattern size of the second pattern projected onto the object 200 .

Furthermore, in the conventional projection device 500 detailed with reference to FIG. Three light sources had to be used, including a third light source for the third pattern plate 520c. On the other hand, in the projection device 1 of the present invention, the first pattern plate 11a and the second pattern plate 11b are provided between the light source 12 and the projection optical system 13 and on the optical axis OA of the projection optical system 13. Therefore, one light source 12 can irradiate the first pattern plate 11a and the second pattern plate 11b with light. Therefore, the number of light sources 12 used in the projection device 1 of the invention is less than the number of light sources used in the conventional projection device 500 . As a result, the manufacturing cost of the projection device 1 can be reduced.

Furthermore, in the conventional projection device 500, the second pattern plate 520b and the third pattern plate 520c are shifted from the optical axis of the projection optical system 510 in a direction perpendicular to the optical axis direction of the projection optical system 510. placed in position. Therefore, the width of the conventional projection device 500 (the length of the projection optical system 510 in the direction perpendicular to the optical axis direction) increases, and the size of the conventional projection device 500 increases. On the other hand, in the projection device 1 of the present invention, since the first pattern plate 11a and the second pattern plate 11b are provided on the optical axis OA of the projection optical system 13, an increase in the width of the projection device 1 is suppressed. can do.

FIG. 7 schematically shows the configuration of the ranging device 2 used in the ranging system 100 of the present invention. As shown in FIG. 7, the ranging device 2 includes a first imaging system IS1 including a first imaging optical system OS1 and a first imaging element S1, a second imaging optical system OS2 and a second imaging element S1. and a first image acquired by the first image sensor S1 and a second image acquired by the second image sensor S2. and a computing unit 5 for calculating the distance to the object 200 based on the parallax with the second image.

Each of the first imaging optical system OS1 and the second imaging optical system OS2 is composed of optical elements such as one or more lenses and an aperture, and has the same characteristics (focal length, aberration characteristics, F-number, front principal point position, , back principal point position, etc.). In the first imaging optical system OS1 and the second imaging optical system OS2, the optical axis of the first imaging optical system OS1 and the optical axis of the second imaging optical system OS2 are parallel, and They are arranged so as to be separated by a distance P in a direction perpendicular to the optical axis direction of the optical system OS1 (or the optical axis direction of the second imaging optical system OS2). Therefore, a parallax exists between the first optical image formed by the first imaging optical system OS1 and the second optical image formed by the second imaging optical system OS2.

The first imaging optical system OS1 collects the light from the target object 200 on which the first pattern and the second pattern are projected by the projection device 1, and onto the imaging surface of the first imaging element S1 the first optical system OS1. forms an optical image of Similarly, the second imaging optical system OS2 collects the light from the object 200 on which the first pattern and the second pattern are projected by the projection device 1, and collects the light onto the imaging surface of the second imaging element S2. forming a second optical image at .

The first imaging element S1 is arranged on the optical axis of the first imaging optical system OS1, captures a first optical image formed by the first imaging optical system OS1, and outputs the first image. have the ability to retrieve The second imaging element S2 is arranged on the optical axis of the second imaging optical system OS2, captures a second optical image formed by the second imaging optical system OS2, and produces a second image. have the ability to retrieve Each of the first imaging element S1 and the second imaging element S2 is a color imaging element having a color filter such as an RGB primary color filter or a CMY complementary color filter arranged in an arbitrary pattern such as a Bayer array. It may be a black-and-white image sensor that does not have such a color filter.

The orientation of the distance measuring device 2 and the orientation of the projection device 1 are such that the optical axis of the first imaging optical system OS1 and the optical axis of the second imaging optical system OS2 are aligned with the optical axis of the projection optical system 13 of the projection device 1. It is set to tilt with respect to OA. Further, the distance measuring device 2 is such that the focusing plane of the first imaging system IS1 and the focusing plane of the second imaging system IS2 of the ranging device 2 are the first focusing plane FP1 of the projection device 1 and the second focusing plane FP1. is preferably configured and arranged to intersect the optical axis OA of the projection optical system 13 of the projection device 1 within the range R between the focal plane FP2 of the projection device 1 and the focal plane FP2. More preferably, in the ranging device 2, the focusing plane of the first imaging system IS1 and the focusing plane of the second imaging system IS2 of the ranging device 2 are aligned with the first focusing plane FP1 of the projection device 1. It is preferably constructed and arranged to intersect the optical axis OA of the projection optics 13 of the projection device 1 at the midpoint of the range R between the second focal plane FP2. With such a configuration, it is possible to accurately measure the distance to the object 200 positioned within the range R between the first focal plane FP1 and the second focal plane FP2 of the projection device 1 .

The first imaging element S1 and the second imaging element S2 perform imaging at the same timing under the control of the arithmetic unit 5, and obtain a first image and a second image, respectively. The first image captured by the first image sensor S1 and the second image captured by the second image sensor S2 are sent to the arithmetic unit 5 .

The computing unit 5 is configured to calculate the distance to the object 200 using the first and second images received from the first image sensor S1 and the second image sensor S2, respectively. As shown in FIG. 8 , arithmetic unit 5 includes one or more processors 51 for executing the operations of arithmetic unit 5 and processors 51 for executing inputs to and outputs from arithmetic unit 5 . and one or more memories 53 storing data 54 and modules 55 used to perform the processing of the arithmetic unit 5 .

The one or more processors 51 include one or more microprocessors, microcomputers, microcontrollers, digital signal processors (DSPs), central processing units (CPUs), memory control units (MCUs), image processing arithmetic processing units ( A computing unit that performs arithmetic operations, such as signal manipulation, based on computer-readable instructions, such as a GPU), state machine, logic circuit, application specific integrated circuit (ASIC), or a combination thereof. In particular, processor 51 is configured to fetch computer readable instructions (eg, data, programs, modules, etc.) stored in memory 53 and to perform operations, signal manipulations and controls.

The I/O interface 52 includes various software and hardware interfaces such as web interfaces, graphical user interfaces (GUIs), and the like. For example, the I/O interface 52 is an interface for peripheral devices such as keyboards, mice, touch panel displays, external memories, printers and displays. The I/O interface 52 enables input to the arithmetic unit 5 using input devices such as a keyboard, mouse, and touch panel display, and output from the arithmetic unit 5 to a display, printer, and external memory.

The memory 53 can be a volatile storage medium (eg, RAM, SRAM, DRAM), a non-volatile storage medium (eg, ROM, EPROM, EEPROM, flash memory, hard disk, solid state drive, SD card, optical disk, CD-ROM, digital computer readable medium comprising a versatile disc (DVD), Blu-ray disc, magnetic cassette, magnetic tape, magnetic disk), or combinations thereof.

The memory 53 is communicably connected to the processor 51 and stores a plurality of modules 55 executable by the processor 51 and data 54 required for processing by the plurality of modules 55 . The memory 53 also has a function of temporarily storing data received, processed, and generated by one or more of the plurality of modules 55 and data required for executing processing by the plurality of modules 55 .

Data 54 include ranging parameters 541 required to measure the distance to object 200 based on the parallax between the first and second images, and and any number of other data 542 required. The ranging parameter 541 is an internal parameter (focal length of the first imaging optical system OS1 and the second imaging optical system OS2, the Aberration characteristics of the optical system OS1 and the second imaging optical system OS2, characteristics such as the number of pixels and the pixel pitch of the first imaging element S1 and the second imaging element S2, etc.) 2 (distance P between the optical axis of the first imaging optical system OS1 and the optical axis of the second imaging optical system OS2, etc.) related to the arrangement of the imaging optical system OS2. The ranging parameters 541 are fixed parameters determined by the configuration and arrangement of the first imaging system IS1 and the second imaging system IS2, and are prestored in the memory 53 . The arithmetic unit 5 calculates the distance to the object 200 based on the parallax between the first image and the second image and the distance measurement parameter 541 .

Modules 55 are computer readable instructions, such as routines, applications, programs, algorithms, libraries, objects, components, data structures, or combinations thereof, executable by processor 51 .

The module 55 includes an imaging control module 551 for controlling imaging by the first imaging element S1 and the second imaging element S2, and extracting feature points in the first image and corresponding feature points in the second image. a feature point extraction module 552 for calculating the distance to the feature points of the target object 200 based on the calculated field of view; Based on this, it includes a depth information generation module 554 for generating depth information of the object 200 and any number of other modules 555 for supplementing the functions provided by the computing unit 5 .

The imaging control module 551 controls the first imaging element S1 and the second imaging element S2 according to the operation input by the user via the I/O interface 52, and the first pattern and the second pattern are It has a function of imaging the projected object 200 . Under the control of the imaging control module 551, the first imaging element S1 and the second imaging element S2 image the object 200 on which the first pattern and the second pattern are projected at the same timing, and the first An image and a second image are respectively acquired.

The feature point extraction module 552 has a function of extracting feature points in the first image acquired by the first image sensor S1 and corresponding feature points in the second image acquired by the second image sensor S2. are doing. Specifically, the feature point extraction module 552 first extracts one of the edges of the first pattern or the second pattern projected onto the object 200 in the first image. are extracted as feature points. The feature point extraction module 552 then searches the second image to detect corresponding feature points corresponding to the extracted feature points in the first image. Extraction of edge portions and extraction of corresponding feature points can be performed by various methods known in the field of distance measurement using a stereo camera method (for example, an edge extraction method using a Sobel filter, detection of corresponding feature points using an epipolar line, etc.). method, etc.). A difference between the coordinates of the feature point in the first image and the coordinates of the corresponding feature point in the second image is calculated, and the difference between the feature point in the first image and the corresponding feature point in the second image is calculated. It is temporarily stored in the memory 53 as parallax.

The feature point extraction module 552 may also extract feature points in the first image and corresponding feature points in the second image by pattern matching. In this case, the feature point extraction module 552 first cuts out an arbitrary region of the first pattern or the second pattern projected onto the object 200 in the first image to a predetermined size, and extracts the template pattern is temporarily stored in the memory 53 as . Next, the feature point extraction module 552 performs pattern matching using the template pattern stored in the memory 53 to extract patterns in the second image that match the template pattern. Pattern matching can be performed using various methods known in the field of image processing, such as geometric shape pattern matching for calculating a correlation coefficient (similarity) between two patterns. A difference between the coordinates of an arbitrary portion of the extracted pattern (template pattern) in the first image and the coordinates of the corresponding portion of the matching pattern in the second image is calculated, and the feature in the first image is calculated. It is temporarily stored in memory 53 as the parallax between the point and the corresponding feature point in the second image. In this case, the pair of feature points used for distance measurement is an arbitrary portion of the extracted pattern (template pattern) in the first image and a corresponding portion of the matching pattern in the second image. be.

The distance calculation module 553 has a function of calculating the distance to the feature points of the object 200 based on the parallax extracted by the feature point extraction module 552 . Specifically, the distance calculation module 553 calculates the parallax between the feature points in the first image temporarily stored in the memory 53 and the corresponding feature points in the second image and the distance stored in the memory 53 . The distance measurement parameter 541 stored in the object 200 is referred to and the distance to the feature point of the object 200 is calculated. The distance to the feature point of the object 200 calculated by the distance calculation module 553 is temporarily stored in the memory 53 . The feature point extraction module 552 and the distance calculation module 553 continue to extract the feature points and the first image until the depth information generation module 554 acquires a sufficient number of distance information for generating depth information of the object 200 . Extraction of the corresponding feature points in the image of 2 and calculation of the distance to the feature points of the object 200 are repeatedly executed while changing the feature points to be extracted.

The depth information generation module 554 has a function of generating depth information of the object 200 based on the distances to the plurality of feature points of the object 200 calculated by the distance calculation module 553 . Specifically, the depth information generation module 554 generates a 3D grid and texture of the object 200 based on the distances to the plurality of feature points of the object 200, and generates a 3D model of the object 200. , is stored as depth information of the object 200 in the memory 53 .

As described above, in the ranging system 100 of the present invention, the projection device 1 projects the first pattern and the second pattern having different imaging positions onto the object 200 . Moreover, as described above, the decrease in luminance of the first pattern and the second pattern projected onto the object 200 by the projection device 1 is greatly suppressed. Therefore, the ranging device 2 can use the first pattern or the second pattern projected onto the object 200 by the projection device 1 as feature points for ranging. As a result, even when the surface of the target object 200 is a smooth curved surface without unevenness, it is possible to acquire a sufficient number of distance information to generate the depth information of the target object 200 .

Also, the first pattern and the second pattern projected onto the object 200 by the projection device 1 are imaged at different positions. Furthermore, since the distance measuring device 2 can use the first pattern or the second pattern projected onto the object 200 as a feature point for distance measurement, the distance measurement range of the distance measuring device 2 is extended. can do.

Referring now to FIG. 9, the ranging method S100 performed by the ranging system 100 of the present invention will be detailed. In step S<b>110 , the user uses the projection device 1 to project onto the object 200 a first pattern and a second pattern whose imaging positions are different from each other. In step S<b>120 , the user operates the arithmetic unit 5 to image the object 200 . When the arithmetic unit 5 receives an operation from the user, the processor 51 of the arithmetic unit 5 uses the imaging control module 551 to control the first imaging element S1 and the second imaging element S2 so that the projection device 1 performs the first imaging. The object 200 on which the first pattern and the second pattern are projected is imaged to obtain a first image and a second image.

In step S130, the processor 51 of the computing unit 5 uses the feature point extraction module 552 to extract the feature points in the first image and the corresponding feature points in the second image, and extract the feature points in the first image. A disparity between the point and the corresponding feature point in the second image is calculated. In step S140, the processor 51 of the arithmetic unit 5 uses the distance calculation module 553 to calculate the distance to the feature point of the object 200 based on the parallax calculated in step S130. Steps S130 and S140 are repeatedly performed by changing the feature points extracted in step S130 until the depth information generation module 554 acquires a sufficient number of distance information to generate depth information of the object 200. be. In step S150, the processor 51 of the arithmetic unit 5 uses the depth information generation module 554 to generate depth information of the object 200 based on the distances to the plurality of feature points of the object 200 calculated in step S140. do. Once depth information for object 200 is generated in step S140, ranging method S100 ends.

Although the projection device and distance measuring system of the present invention have been described above based on the illustrated embodiments, the present invention is not limited thereto. The configurations of the projection device and the ranging device described above can be replaced with anything that can perform similar functions, or any configuration can be added to the projection device and the ranging device.

For example, the numbers and types of components of the projection device shown in FIG. 3 and the ranging device shown in FIG. 7 are merely illustrative examples, and the present invention is not necessarily limited thereto. It is within the scope of the present invention that any components may be added or combined, or any components omitted without departing from the principles and intent of the present invention. Also, each component of the projection device and the ranging device may be implemented in hardware, software, or a combination thereof.

Also, in the above description, the distance measuring device uses the parallax between the two images to calculate the distance to the object, but the present invention is not limited to this. For example, the distance measuring device measures the distance to the object based on information other than parallax, such as the positions of the dots of the first pattern or the second pattern projected onto the object and the intersection points in the image, and phase difference information. The distance to the object may be calculated by various methods known in the ranging field (active stereo method, etc.). Such embodiments are also within the scope of the present invention.

Reference Signs List 1 projection device 11a first pattern plate 11b second pattern plate 12 light source 13 projection optical system 14 transparent structure 2 ranging device 3 random dot pattern 31 dots 4 random lattice pattern 41 Grid line 42 Intersection point 5 Arithmetic unit 51 Processor 52 I/O interface 53 Memory 54 Data 541 Ranging parameter 542 Other data 55 Module 551 Imaging control module 552 Feature point extraction module 553 Distance calculation module 554 Depth information generation module 555 Other modules 100 Ranging system 200 Object 500 Projection device 510 Projection optical system 520a First pattern plate 520b Second pattern plate 520c Third pattern plate Pattern plate 530a First half mirror 530b Second half mirror 540a First focal plane 540b Second focal plane 540c Third focal plane D Distance FP1 First focus Plane FP2 Second focal plane IS1 First imaging system IS2 Second imaging system OA Optical axis OS1 First imaging optical system OS2 Second imaging optical system P Distance R Range S1 1st image pickup device S2 2nd image pickup device S100 Distance measuring method S110, S120, S130, S140, S150 Steps

Claims (6)

a first pattern plate having a first pattern;
a second pattern plate having a second pattern;
a light source for irradiating the first pattern plate and the second pattern plate with light;
projection for projecting the first pattern and the second pattern onto an object by condensing the transmitted light irradiated by the light source and transmitted through the first pattern plate and the second pattern; an optical system;
A projection device, wherein the first pattern plate and the second pattern plate are provided on the optical axis of the projection optical system and between the light source and the projection optical system. 2. The projection device according to claim 1, wherein the first pattern plate is provided on the optical axis of the projection optical system and closer to the light source than the second pattern plate. 3. The projection device according to claim 2, wherein the pattern size of said first pattern is larger than the pattern size of said second pattern. 4. A projection device according to claim 2 or 3, wherein the pattern density of said first pattern is lower than the pattern density of said second pattern. 3. Each of said first pattern and said second pattern is a random dot pattern composed of a plurality of randomly arranged dots or a random lattice pattern composed of a plurality of randomly extending grid lines. 5. A projection device according to any one of 1 to 4. a projection device according to any one of claims 1 to 5;
a ranging device configured to measure a distance to the object by imaging the object onto which the first pattern and the second pattern are projected. distance system.

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