JPH0629708B2 - Distance gate imaging method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a distance gate imaging method and apparatus, and more particularly, to irradiating the surface of an object to be imaged with slit light and scanning the surface to obtain an optical image of the surface of the object to be imaged. The present invention relates to an imaging method and apparatus for obtaining information regarding distance from an image in a non-contact manner.

[Prior Art] Non-contact extraction of distance (depth) information using an optical system is an indispensable technique for three-dimensional object shape processing by computer application.

In extraction of distance information using an optical system, typical data obtained first is a distance image. This distance image is one in which each pixel value reflects the distance from the camera, rather than each pixel value representing lightness as in a normal grayscale image.

This range image is rarely used as it is, and is used after being converted into a form suitable for the content of the three-dimensional shape processing. In particular, in three-dimensional component identification in a production process, a plurality of images obtained by binarizing a distance image with a certain distance as a threshold value are obtained by changing the threshold value, and from each image,
It has been proposed to calculate geometric features such as area, length, and the center of gravity, and to identify them based on these features (IEICE Transactions, Vol.J69-D, No.1, pp. .111 to 112, 1
January 986). This is to reduce the amount of data to be handled, and at the same time, shorten the processing time, by not using the distance image as it is, but using it after binarizing it when performing the three-dimensional object shape identification processing. is there. In the following, an image obtained by binarizing a distance image with a certain fixed distance as a threshold value or an image binarized depending on whether it is within a certain distance range will be referred to as a distance gate image.

Conventionally, in order to obtain the range gate image, the method of once obtaining the range image and then binarizing the range image as described above has been used. Therefore, first, a method of obtaining such a conventional range image will be described.

Passive stereo method and active stereo method are typical conventional methods for non-contact optical range image acquisition. The passive stereo method is based on the principle of binocular stereoscopic vision.
A three-dimensional object is imaged by a camera or the like from a plurality of viewpoints, and a distance image is obtained from the plurality of imaged images and the viewpoints and viewing directions at the time of imaging using the principle of triangulation. At this time, it is necessary to perform a corresponding inspection / detection process on which one point in the image captured from a certain viewpoint corresponds to which point in the image captured from another viewpoint. For that purpose, a large storage capacity and processing procedure are required. , Requires processing time.

The active stereo method replaces the image pickup from one viewpoint of the passive stereo method with irradiation of spot light or slit light. The most practical method among the active stereo methods is the light cutting method using slit light. This light-section method irradiates a target three-dimensional object with slit light, and the resulting optical image of the object surface is captured from a viewpoint away from the plane in which the slit light extends, and an optical image is formed on the image capturing surface. This is a method for obtaining the spatial coordinates of the optical image on the object surface by using the principle of triangulation based on the geometrical positional relationship between the plane covered by the slit light and the imaging system, and the above corresponding point detection processing is unnecessary.

As an example of this light cutting method, a plane equation formed by slit light is used, in which the irradiation direction of slit light is computer-controlled and an optical image on the object surface by the slit light is captured by an image input device using a TV camera or the like. There is one that calculates the three-dimensional coordinates of the optical image of the object surface from the input image. In this case, only one image capture can calculate the three-dimensional coordinates of the optical image portion on the surface of the object illuminated by the slit light, but by deflecting and scanning the slit light little by little and repeating the image input, A large number of three-dimensional coordinates are obtained, and a range image can be obtained as a result.

Incidentally, in order to avoid the repetition of image input in such a light cutting method, a slit light which is scanned at high speed is irradiated,
There is also a proposal to obtain a distance image at high speed by using a special solid-state image sensor having a function of storing the time when the optical image on the object surface by the slit light passes each pixel on the solid-state image sensor. (Journal of the Institute of Electronics, Information and Communication Engineers, Vo
l.J70-D, No.5, pp.1053-1055, 1987 5
Month). However, this method requires the use of a special solid-state image sensor capable of storing time, which is not practical at present.

After all, in order to obtain the range gate image by the conventional method,
It is necessary to obtain a range image once by the light section method or the like, and further perform a process such as binarization as a constant distance threshold value or binarization depending on whether a certain distance range exists.

[Problems to be Solved by the Invention] According to the conventional light section method as described above, in order to obtain a range image, image input is performed once for each slit light deflection operation, and this is performed by slit light. Will be repeated for the number of deflection operations required to scan the entire object surface. Therefore, for example, when image input is performed using a normal industrial TV camera, it takes at least 1/60 to 1/30 second for one image input, and it is necessary to finally obtain a range image. There was a problem that it took a long time.

In addition, since some kind of binarization processing is required to obtain the range gate image from the range image, it is almost impossible to obtain the range gate image or the range gate image of a moving object in real time. It was in a state.

The present invention has been made in view of such conventional problems, and an object thereof is to directly obtain a distance gate image equivalent to an object to be imaged by using slit light without once obtaining the distance image. An object is to provide an imaging method and apparatus for imaging at a speed.

[Means for Solving Problems] A distance gate imaging method of the present invention scans slit light along a surface of an object to be imaged, and forms an optical image of the surface of the object to be imaged by the slit light at a predetermined opening. And moving the opening on the shutter surface in synchronization with the scanning of the slit light, and moving the optical image that moves on the shutter surface in accordance with the scanning of the slit light. Only the optical image that has passed through the opening is exposed on the imaging surface, and only the surface of the imaging object within a predetermined distance range of the imaging object surface is imaged.

Further, the distance gate imaging device of the present invention includes a deflection irradiation device that deflects and scans the slit light toward the surface of the object to be imaged,
An optical system for forming an optical image of a surface of an object to be imaged by the slit light on a shutter surface, a moving means for moving a predetermined opening on the shutter surface in synchronization with scanning of the slit light, Of the optical images formed on the shutter surface, only the optical image that has passed through the moving aperture is selectively exposed.

[Operation] As described above, in the present invention, the surface of the object to be imaged is irradiated while deflecting and scanning the slit light, and an optical image on the surface of the object to be imaged generated by the slit light is formed on the shutter surface by the optical system. Then, by selectively exposing and accumulating the optical image of the surface of the object to be imaged which moves on the shutter surface with the scanning of the slit light to the imaging surface through the opening on the shutter surface which moves simultaneously with the scanning of the slit light, It is possible to capture an image of only the portion within the desired distance range on the surface of the object to be imaged, that is, a distance gate image, without repeating the operation of deflecting the slit light little by little and inputting an image like the light cutting method. However, by performing the slit light scanning and the movement of the opening of the shutter at a high speed, it becomes possible to capture a range gate image in real time.

[Embodiment] A preferred embodiment of the present invention will be described below with reference to the drawings.

First Embodiment FIG. 1 is a perspective view showing the overall configuration of an embodiment of the present invention,
FIG. 2 is a plan view thereof, and FIGS. 3 to 6 show the configuration of the main part thereof.

The light source 10 that irradiates the slit light R in a predetermined direction is capable of deflection scanning. For example, scanning is performed from the left to the right at a cycle of about 1/60 or 1/30 seconds as indicated by an arrow in the figure. As a result, the slit light R becomes
Scanned along two surfaces.

Further, the shutter 14 is moved in synchronization with the scanning of the slit light R. The shutter 14 has a shutter slit 16 in the center thereof, and an image pickup surface 18 is formed behind the shutter slit 16. The shutter 14 and the image pickup surface form a part of the TV camera C.

In this way, the shutter 14 of the TV camera C is set to the slit light L.
When it is moved in synchronism with the scanning of 1, the light passes through the shutter slit 16 and the image pickup surface 18 is exposed only when the surface of the imaged object is present at a predetermined position.

The geometrical relationship of each element of the embodiment shown in FIG. 1 will be described. FIG. 2 shows a view of FIG. 1 seen from above (y-axis direction). Hereinafter, for simplification, consider a two-dimensional plan view (x, z plane) viewed from above. With the center O of the lens 20 as the origin, the shutter slit 16 and the shutter slit line (surface) passing through the origin are S, and the mirror 10 that scans the slit light R.
The center of rotation of b is M (x _M , z _M ), the slit light passing through M is R, and the angle formed by the slit light with the z axis is θ _R. Further, it is assumed that an axis that passes through the focal point z = -f of the lens and is parallel to the x axis in the opposite direction is a, and the coordinates of the shutter slit 16 on the axis a are a _s . Then, the shutter slit line S: Slit light _{R: x-x M = -tanθ} R · (z-z M) (2) the intersection of the S and R is The relationship between a _s and θ _R for S and R to intersect with each other at the equidistant surface z = z ₀ is as follows. When z in formulas (1) and (2) is set to z ₀ and x is deleted, In this way, the opening of the shutter 14 is formed into a slit-like shutter slit 16, and the position a of the shutter slit 16 is a.
_{If s} and the deflection angle θ _R of the slit light R are moved synchronously according to the relationship as shown in equation (5), the shutter slit surface S passing through the plane formed by the slit light R and the center O of the shutter slit 16 and the lens 20. The intersection line with and moves along the equidistant surface V (z = z ₀ ).

In this case, what is actually exposed on the imaging surface 18 is a line of intersection between the equidistant surface V and the surface of the object 12. That is, object 1
The imaging surface 18 is exposed only when the surface of 2 is on the equidistant surface V. Therefore, as a result, an equidistant line at a certain distance of the three-dimensional object, that is, a distance gate image can be captured in one scan, that is, in one TV frame period. Further, by repeating the movement of the shutter 14 and the scanning of the slit light R, it is possible to directly look at the TV monitor.

Further, regarding the control of the scanning of the slit light R and the movement of the slit-shaped opening, for example, the jack slit 16, the distance gate image for the equidistant surface V at the desired distance is appropriately changed. Can be obtained.

Note that the range gate image directly captured in the present invention is slightly different from the conventional meaning that the range image is binarized, and the image of the imaged object without the shutter is taken from the imaged object surface. It means an image in which only a surface portion existing within a predetermined distance range is taken out. However, in the present invention, by binarizing the range gate image directly imaged at an appropriate brightness level, an image substantially the same as the range gate image in the conventional sense can be obtained. There is no need to distinguish between.

Further, if the width of the shutter slit 16 is increased, the range of light that can pass through the shutter slit 16 is expanded. That is, the shutter slit surface S spreads in the x-axis direction, and the object 1
When 2 is in the range corresponding to the width of the shutter slit 16, the image pickup surface 18 is exposed.

Therefore, the configuration of the shutter slit 16 will be described with reference to FIG. That is, as shown in FIG. 3A, if a sufficiently thin shutter slit 16 is formed as the reference line of the shutter 14, that is, the shutter slit surface S corresponding to the slit light R, it is possible to image only the equidistant surface.
Further, as shown in FIG. 3B, if a large opening is provided on the right side of the reference line (the positive direction of the x-axis), only the portion behind the equidistant surface V can be imaged, and as shown in FIG. If a large opening is provided on the left side of the line (x-axis negative direction), the equidistant surface V
It is possible to take an image of only the part in front.

It should be noted that when mechanically operating the shutter 14 having the shutter slit 16 that is an opening, it is difficult to accurately match the image pickup surface 18 and the shutter 14 surface. However, if the two planes do not match exactly, the edge of the opening is blurred and a sharp distance gate image cannot be obtained. Therefore, as shown in FIG. 4, in addition to the lens 20, a lens group 22 may be provided between the shutter 14 and the image pickup surface 18 to optically match both surfaces.

In this case, there is an advantage that what is placed on the image pickup surface 18 can be freely selected from various image pickup elements, photographic films, etc. according to the purpose of image pickup. It is also possible to place an appropriate optical system here and look directly.

It is preferable to scan the surface of the object to be imaged with the slit light R described above by rotating the light source 10 of the slit light R or a mirror that reflects the light. Of course, in the present invention, in addition to the method of rotating the light source 10 or the mirror, for example, a method of moving the slit light source 10 in parallel, or a method of moving it in a fan shape toward a fixed point is also possible.

In addition, in this embodiment, the light source 10 of the slit light R is a TV.
Although it is arranged on the right side of the camera C, it is of course possible to arrange it on the left side. Further, since the slit light R is radiated onto the object 12 from an oblique direction, there is a possibility that a so-called blind spot occurs on the surface of the object which the TV camera C can see but which is not hit by the slit light R. To reduce this blind spot, T
It is also possible to place one slit light source on each of the left and right sides of the V camera C and scan the left and right slit light sources alternately. At this time, the shutter slit 16 may be left as it is in the case of the sufficiently thin shutter slit of FIG. 3A.
In the case of FIGS. 3B and 3C, when the left and right slit light sources are switched, it is necessary to switch the shutter slit 16 from FIG. 3B to C or from FIG. 3C to B at the same time.

Further, as an optical system for forming an optical image on the surface of the object to be imaged, which is generated by the slit light, on the surface of the shutter 14, an ordinary camera lens with little image distortion is suitable. However, this is not the case when aiming for a special effect such as when obtaining data about a specific curved surface.

That is, the control of the relationship between the slit light scanning and the movement of the opening of the shutter is basically performed on the assumption of an equidistant plane, but is assumed to be a plane inclined by the equidistant plane or a simple curved surface. It is also possible to do so.

FIG. 5 shows an example of a specific configuration of the shutter 14.

A slide table 24 is provided above and below the movable shutter 14, and the slide table 24 is used as a slide receiving table 2 of a frame 26.
We support 8.

A crank 32 driven by the motor 30 is engaged with the shutter 14. Therefore, the rotation of the motor 30 is converted into a left-right reciprocating motion, and the shutter 14 reciprocates left and right. As the motor 30, for example, a stepping motor is adopted.

Both ends of the shutter 14 are supported by the mount 26 via springs 34. Therefore, when the engagement protrusion 32a of the crank 32 is processed, the shutter 14 is moved to the right in the drawing by the engagement protrusion 32a. When the shutter 14 moves upward, the force of the spring 34 causes the shutter 14 to move to a predetermined position. Held in position. Further, the shutter 14 may be provided with a slit that engages with the engagement protrusion 32a, and the shutter 14 may reciprocate.

Further, the motor 30 has a built-in encoder. Then, this encoder outputs a signal in synchronization with the rotation of the motor 30. If the scanning of the slit light R in the light source 10 is controlled by this signal instead of corresponding to the scanning of the light source 10, the synchronization of the movement of the slit light R and the shutter 14 is achieved.

FIG. 6 shows another example of the shutter 14 in which the width of the shutter slit 16 is adjustable.

In this example, the shutter 14 is formed of a fixed mask 40 and a movable mask 42. The gap between the fixed mask 40 and the movable mask 42 is the shutter slit 16.

The lower part of the movable mask 42 is slidably supported by the shutter base 14a, and its movement is adjustable by rotation of the screw 44. The base 44a of the screw 44 is formed, for example, in a hexagonal shape, and penetrates through a hole formed in the adjusting screw 46 so as to correspond thereto. Therefore, the position of the movable mask 42 with respect to the fixed mask 40, that is, the width of the shutter slit 16 can be adjusted by rotating the adjusting screw 46.

Further, the base portion 14 a of the shutter 14 is slidably supported by the frame 26. Then, the crank 32 reciprocates left and right.

Further, as shown in FIG.
It may be configured with 6. This film 46 has a transparent portion 46.
a and a mask portion b, and the overlapping portion of the transparent portion 46a formed by combining the two films 46 forms the shutter slit 16. That is, if the two films 46 are moved at a constant speed by the rotation driving of the roller 38, the shutter slit 16 formed by the two films 46 will move. If the roller 38 moves in the direction of the arrow in the figure, the shutter slit 16 will move to the right.

Then, if the movement of the shutter slit 16 is synchronized with the slit light L, the optical image passes through this shutter slit only when the surface of the object to be imaged is on the equidistant surface V as in the case described above, and the distance is increased. A gate image is obtained.

The synchronization control of the film 46 is performed by the photodetector 48.
Based on the detection result of. Alternatively, a mark for detection by the photodetector 48 may be separately provided on the film 46, and synchronization control may be performed according to the position of this mark.

Further, according to this embodiment, since the movement of the shutter slit 16 can be controlled by the rotation of the roller 38, high-speed movement can be performed accurately, and the mechanism for movement is simpler than the reciprocating movement. Further, since the synchronization can be controlled by the detection result of the photo detector 48, the two films 4
The shutter slit 1
You can also change the width of 6.

In the conventional light cutting method, the geometrical relationship between the slit light and each device is known, and the three-dimensional coordinates of the optical image of the object surface are calculated from the optical image formed on the imaging surface by the principle of triangulation.
On the other hand, in order to obtain the distance gate image, it is necessary to judge whether the depth coordinate, that is, the distance is within a predetermined range, instead of calculating the three-dimensional coordinate.

In the present invention, the shutter 14 that moves simultaneously with the scanning of the slit light R is used to determine whether the distance is within a predetermined range.
It depends on whether the optical image passes through the opening of. Therefore,
If the shape of the opening of the shutter 14 and the relationship between the scanning of the slit light R and the movement of the opening are appropriately controlled, the imaging surface 18 can be obtained.
The optical image that reaches is only the optical image within the predetermined distance range among the optical images on the surface of the object 12. Therefore, scanning of the slit light R and movement of the opening of the shutter 14 are performed at high speed,
By using a normal image pickup tube, a solid-state image pickup device, a photographic film, or the like capable of accumulating an image for one scanning period of the slit light R as the image pickup surface 18, it is possible to take a range gate image in a remarkably short time.

Second Example Regarding an example in which a shutter function is realized on a solid-state image sensor,
Description will be made with reference to FIGS. 8 to 9.

That is, in this example, the normal interline transfer method CC
For the D (IT-CCD) image pickup device, an image pickup device to which a shutter control circuit is added to control whether the signal charge of the photodiode is flown into the drain for each column or row and is discarded, or is stored in the capacitor adjacent to the photodiode is used. .

Fig. 8 shows an ordinary IT-CCD (charge coupled devic).
e) A conceptual diagram of the image sensor 50 is shown. Normal IT like this
In the CCD image pickup device 50, a plurality of vertical CCDs 54 are connected to a horizontal CCD 52. And vertical CC
In D54, a group of photodiodes 56 is provided with the MOS switch 5
8 are connected. Further, each MOS transistor switch 58 is controlled by the signal φ _pt .

During the vertical retrace period of the video signal Sv (the period when VSYNC is ON), φ _pt is turned on and the MOS transistor switch 58 is turned on. Then, the signal charges accumulated in each photodiode 56 are read out to the vertical CCD 54 all at once through the MOS transistor switch 58. Then, the horizontal CCD 52 and the vertical CCD 54 are controlled by clock pulses (not shown) to output one pixel at a time to form a video signal Sv.

As described above, in the normal IT-CCD image pickup device 50,
One photodiode 56 and MOS transistor switch 5
One set of 8 corresponds to one pixel.

Here, in the present invention, in order to realize the shutter mechanism in the IT-CCD image pickup device 50, one pixel is changed as shown in FIG. 9A, and the whole is constructed as shown in FIG. 9B. That is, the MOS transistor switch 5 is provided between the photodiode 56 and the MOS transistor switch 58.
8c and one set of the capacitor 60 are inserted. The photodiode 56 is connected to the drain via another MOS transistor switch 58d. The MOS transistor 58c connected to the capacitor 60 is controlled by the signal φ _ci , and the MOS transistor switch 58d connected to the drain is controlled by the signal φ _di . The MOS transistor switch 5
Φ _pt controlling 8 is a signal similar to that of FIG.

Here, φ _ci and φ _di are shutter control signals for the column number i and are signals having opposite phases. That is, the column number i
Regarding, when φ _ci is OFF and φ _di is ON, the signal charge of the photodiode 56 begins to flow to the drain and is discarded, which corresponds to OFF of the shutter. When φ _ci is ON and φ _di is OFF, the signal charge of the photodiode 56 is stored in the adjacent capacitor 60, which corresponds to opening of the shutter.

By doing so, it is the charges accumulated in each capacitor 60 that are read out to the vertical CCD 54 by the signal φ _pt all at once.

Since the signal φ _pt is turned on during the vertical blanking period, it is necessary to avoid the shutter operation during this period and avoid the collision between the shutter operation and the signal reading operation.

Then, if φ _ci and φ _di are controlled at appropriate timings during the period other than the vertical blanking period, the opening area of the shutter slit 16 can be controlled. That is, a slit-shaped opening, a right side opening, and a left side opening can be realized.

As described above, according to this embodiment, since the movement of the shutter can be electronically controlled, it is very easy to accurately synchronize the movement with the slit light L of the light source 10 for scanning.

Ideally, the fixed image pickup device is used as the image pickup device, and the shutter 14 is electronically realized on the solid-state image pickup device. This is because the surface of the shutter 14 and the imaging surface 18 can be exactly matched with each other, and there is an advantage that the shape and movement of the opening of the shutter 14 can be completely electronically controlled.

Third Embodiment In this embodiment, instead of using a two-dimensional image sensor and a shutter, the line sensor 70 is moved in synchronization with scanning of slit light on the focal plane. By doing so, an image similar to that when the opening has a slit shape is obtained on the line sensor 70.

Further, if the line sensor 70 is fixed and the incident light is scanned by the mirror 72, the image pickup unit can be simplified.

Therefore, a case where incident light is scanned by a mirror will be described based on the plan view of FIG.

The line sensor 70 is fixed in the vertical direction. Also, the mirror 72
The surface is also vertical. The point on which the line sensor 70 is placed is P, and the point on the focal plane of the optical image to be imaged is P '. Then, the vertical bisector of P and P'is set to 1 pp, and the mirror 72 is placed on this 1 pp. P'through the center of lens 20
Let C be the intersection of the rays 1p and 1pp. The light ray 1p enters the mirror 72 at an incident angle θ and is reflected at a point C. This θ, the triangle CPP 'is an isosceles triangle, and 1 pp is the perpendicular bisector of the line sentence PP', so it is equal to the angle formed by 1 pp and the straight line CP. Therefore, the light reflected at the point C reaches the point P.

From this, if the point P'is moved and a mirror is placed on the perpendicular bisector of P and P ', the image which should be formed at the point P'is formed at the point P. Therefore, the mirror 7 is synchronized with the scanning of the slit light.
If 2 is rotated according to the above-mentioned law, the line sensor 70 can be moved only when the surface of the object 12 to be imaged is on the equidistant plane V.
Image on top. Thereby, a range gate image is obtained.

It should be noted that the mirror 72 can be driven by using a known camera having a built-in mirror for scanning with the same structure. As such a camera with a built-in mirror, for example, there is a CCD mirror scan camera MSC-2000 (Nippon-Hiratsu Co., Ltd.).

Fourth Embodiment In this embodiment, the shutter slit 16 is a vertical slit opening, and the slit light R from the light source 10 is also a vertical slit light.

First, the geometrical relationship of each element of this embodiment will be described. FIG. 11 shows a view seen from above (y-axis direction).

Here, FIG. 11 shows the z coordinate Z _M = 0 of the center M of the rotary scanning of the slit light R in FIG. Further, a rotating mirror 10b is provided at M, and the slit light formed by the laser light source 10a and the cylindrical lens 10c is guided to the rotating mirror 10b, and the slit light R is rotationally scanned by the rotating mirror 10b. At this time, when put intersection between the slit light beam R and the axis a and _{a R, a R = -x M} -f · tanθ R (6) Then, the formula (5) _{is, · a s -a R = x} M (F / z ₀ +1) (7) The right side of Expression (7) is a constant if z ₀ is regarded as a constant. Therefore, if a _s −a _R, that is, the length of the base of the triangle in FIG. 12 is kept constant, the shutter slit line S and the slit light R intersect on the equidistant surface. Then, if the length of the base is changed, the equidistant surface moves back and forth.

An embodiment of the distance gate imaging device using the above principle will be described with reference to FIG.

The structure of the shutter 14 is similar to that shown in FIG. That is, the gap between the fixed mask 40 and the movable mask 42 is formed in the shutter slit 16, and the movable mask 4
By moving 2 relatively with the screw 44,
The width of the shutter slit 16 can be adjusted.

The shutter 14 is vibrated by the crank 32, and the shutter 14 is transmitted to the slide base 82 by the connecting device 80. In this example, the crank 32 and the slide base 82 are connected, and the reciprocating motion of the slide base 82 is transmitted to the shutter 14.

The slide base 82 is provided with an engagement protrusion 82a,
The engagement protrusion 82a is engaged with the elongated hole 84a of the rotary arm 84. Then, the swing of the rotating arm 84 is transmitted to the mirror support member 88 via the arm 86, and the mirror 10b reciprocally rotates to cause the laser light source 10a and the cylindrical lens 10 to rotate.
The slit light formed by c is scanned. Then, in this way, the angle θ _R of the slit light R rotationally scanned becomes as shown in FIG.

In addition, the laser light source 10a and the cylindrical lens 10c
Is installed so that the slit light formed by both proceeds on the X axis in the X + direction. Then, the normal direction of the mirror 10b that scans the slit light R needs to be exactly half of the angle formed by the slit light R and the x-axis.
Such rotation is achieved in the embodiment of FIG.

As a result, the optical image passes through the shutter slit 16 only when the surface of the imaged object 12 is on the equidistant surface V.

Fifth Embodiment In this embodiment, a rotary shutter slit and rotary slit light are used.

Although it is ideal to use the vertical shutter slit and the vertical slit light as in the fourth embodiment, a considerably complicated mechanism is required for high-speed scanning while mechanically synchronizing the two. Therefore, in this embodiment, the rotary shutter slit and the rotary slit light are used instead.

First, assume that there is a rotary shutter having a shutter slit 16 as shown in FIG. In order to enable distance gate imaging with such a shutter 14, what kind of slit light should be emitted is that the slit aperture is back projected through a lens on the equidistant surface V of z = z _0. It is only necessary to irradiate the slit light from the side of the camera so as to match the obtained straight line.

In the case of the rotary shutter 14 of FIG. 13, a straight line on the z = z ₀ plane obtained by backprojecting the shutter slit 16 is a point C _zo (O, − (y _Rs / f) · z ₀ , z _0. ), The inclination becomes a straight line that matches the inclination of the shutter slit 16. That is, when the shutter 14 rotates, the back-projected straight line is also point C.
Rotate at the same angle around _Z0 . Therefore, it is understood that such rotating slit light R should be emitted from the side of the camera.

In order to realize such rotating slit light R, as shown in FIG. 14, laser light is emitted from the light source 10a and is applied to the mirror 10b via the cylindrical lens 10c. Then, when the mirror 10b is rotated and the slit light R matched with the rotation axis is incident, the mirror 10b is rotated about the rotation axis of the mirror 10b.
The slit light R that rotates at a speed twice as high as the rotation speed of is obtained. Therefore, the rotating mirror 10b is installed so that the rotation center of the rotating mirror 10b is directed to the point C _ZO , and the slit light R is incident on the mirror 10b so as to coincide with the rotation axis of the mirror 10b.
It is sufficient to rotate b appropriately.

Here, the slit light R and the rotary shutter 14 on the z = z ₀ plane.
When the back projection of the shutter slit 16 of
The problem is that the rotation angle of the rotary shutter 14 and the rotation angle of the slit light R about the rotation axis do not always match.
That is, since the slit light R is emitted obliquely from the side of the camera, the rotation axis of the rotary shutter 14 and the rotation axis of the slit light R are not parallel.

In order to solve this point, the following mechanism is provided.

(1) A rotary shaft parallel to the rotary shaft of the rotary shutter 14 is set so as to rotate equally to the rotation of the rotary shutter 14, and a so-called universal joint 100 as shown in FIG. Joint 1
The rotation axis of the mirror 10b is rotated via 00. According to this universal joint 100, the rotating shaft 102 and the rotating shaft 104 can be connected at an arbitrary angle.

(2) Since the rotation of the mirror needs to be half the rotation of the slit light R, the rotation of the rotation axis of the mirror 10b is decelerated by half through a speed reducer 110 as shown in FIGS. 16A and 16B. The mirror 10b is rotated.

Ball bearing type speed reducer 110 of FIG. 16A
According to the above, the rotation of the drive shaft 112 is converted into a circular movement of the ball 114 at a speed half that speed, and the driven shaft 116 is thereby rotated. Therefore, the rotational speed of the driven shaft 116 is half that of the drive shaft 112. According to the reduction gear transmission 110 shown in FIG. 16B, the drive shaft 112 is rotated by the gear 11
The rotation speed is reduced to 1/2 by 6a, b, c and d and transmitted to the driven shaft 114. That is, the gear comparison between the gear 116a and the gear 116b is 1: 2, and the gear comparison between the gear 116c and the gear 1 is 1.
The 16d gear comparison is 1: 1.

Here, the step of decelerating the rotation by half by the reduction gear 110 is performed via the universal joint 100 through the mirror 10b.
Don't be as a pre-driving stage.

That is, [rotation equal to that of the rotary shutter 14] → [universal joint 100] → [1/2 reduction gear 110] → [mirror 1
0b rotation] in order. [Rotation equal to rotation shutter 14] → [1/2 reduction gear 110] → [Universal joint 100] → [Mirror 1
0b rotation].

FIGS. 17A, 17B and 17C show the outline of the entire system using a rotary shutter with a fixed slit width. In this case, only one drive motor is required, and the shutter 14 and the slit light R are reliably synchronized.

In this embodiment, the rotary shutter 14 is rotated by the belt 118, the universal joint 100, and the speed reducer 1.
It is converted into rotation of the mirror shaft 120 via 10. This mirror axis 1
Reference numeral 20 corresponds to a straight line passing through the rotation center of the rotary shutter and the center of the lens 20 when viewed from the x-axis direction as shown in FIG. 17A, and the mirror axis 120 when viewed from the y-axis direction as shown in FIG. 17B.
The extension direction of is toward the point z ₀ .

Here, the other end of the mirror shaft 120 is supported by a support pipe 122 that is movable only in the x-axis direction. And
The support pipe 122 is rotatably supported by a movable pipe 124 that is movable in the x-axis direction in order to move the support pipe 122 in the x-axis direction. Therefore, by adjusting the movement of the moving pipe 124, the first direction can be adjusted without changing the direction of the mirror axis 120 when viewed from the x-axis direction as shown in FIG. 17A.
As shown in FIG. 8B, the direction of the mirror axis 120 when viewed from the y-axis direction can be changed, and thus the point z _0, that is, the equidistant plane V can be changed.

Further, the spot light from the light source 10a that emits the laser light is, as shown in FIG.
The slit light is formed by c, and the mirror 10b of the mirror axis 120 is formed.
Is reflected by the object 12 and is irradiated onto the object 12 to be imaged.

Since the rotation of the mirror 10b and the rotation of the rotary shutter 14 are synchronized, the optical image passes through the shutter slit 16 only when the object 12 is on the predetermined equidistant plane V. This produces a range gate image.

In addition, the laser light source 10a and the cylindrical lens 10c
The table 126 that supports and is rotatable, so that the equidistant surface V can be changed.

Further, FIG. 18 shows the rotary shutter 14 in which the width of the shutter slit 16 is adjustable. This is such that the width of the shutter slit 16 can be changed by changing the phases of both the rotary shutter members 130 and 132 using two motors. That is, in this example, the rotary shutter members 130 and 132 are driven by different motors.

Further, the rotary shutter members 130 and 132 may be driven by one motor using a device such as a differential gear, and the width of the shutter slit 16 may be changed.

According to such a method using the rotary shutter slit and the rotary slit light, the high speed scanning of the slit light and the synchronization of the shutter can be achieved.

[Effects of the Invention] As described above, according to the distance gate image capturing method and apparatus of the present invention, the slit light is deflected little by little by performing the slit light scanning and the shutter opening movement at high speed. It is possible to capture an image of only a portion within the desired distance range on the surface of the object to be imaged, that is, a distance gate image in real time without repeating the operation of inputting.

[Brief description of drawings]

FIG. 1 is a perspective view showing the overall configuration of a first embodiment of a distance gate image pickup device according to the present invention, FIG. 2 is a plan view showing the overall configuration of the same embodiment, and FIG. FIG. 4 is an explanatory diagram showing a configuration example of the shutter 14, FIG. 4 is a schematic diagram showing a configuration example of the TV camera of the same embodiment, FIG. 5 is a perspective view showing a configuration example of the shutter 14 of the same embodiment, and FIG. FIG. 7 is a perspective view showing still another configuration example of the shutter 14 of the same embodiment, FIG. 7 is a perspective view showing still another configuration example of the shutter 14 of the same embodiment, and FIG. 8 is a configuration of a conventional solid-state imaging device 50. 9 is a schematic diagram for explaining the configuration of the solid-state imaging device 50 in the second embodiment, FIG. 10 is a schematic diagram for illustrating the overall configuration of the third embodiment, and FIG. Is a schematic diagram showing the overall construction of the fourth embodiment, and FIG. 12 is a plan view showing the construction of the essential parts of the same embodiment. FIG. 13 is a schematic diagram for explaining the position of the rotary shutter 14 of the fifth embodiment, FIG. 14 is a schematic diagram for explaining the generation state of the slit light R of the same embodiment, and FIG. The perspective view which shows the structure of the universal joint 100 of the same Example, FIG. 16 is the schematic for demonstrating the structure of the reduction gear transmission 110 of the same Example, and FIGS. 17A, B, C are the principal parts of the same Example. 18 is a perspective view showing the configuration of the rotary shutter 14 in the x, y, and z-axis directions, respectively, and FIG. 18 is a perspective view showing a configuration example of the rotary shutter 14 of the embodiment, 10 ... Light source 12 ... Object 14 ... Shutter 16 ... Shutter slit 18: Imaging surface C: TV camera V: Equidistant surface

Claims (2)

[Claims] 1. A slit light is scanned along a surface of an object to be imaged, and an optical image of the surface of the object to be imaged by the slit light is guided onto a shutter surface having a predetermined opening, and
Only the optical image that has passed through the moving opening of the optical image that moves on the shutter surface according to the scanning of the slit light is moved in synchronization with the scanning of the slit light. A distance gate imaging method in which an imaging surface is exposed and only the surface of the imaging object within a predetermined distance range of the imaging object surface is imaged. 2. A deflection irradiation device that deflects and scans the slit light toward the surface of the object to be imaged, an optical system that forms an optical image of the surface of the object to be imaged by the slit light on a shutter surface, and the slit. Only moving means for moving a predetermined opening on the shutter surface in synchronization with scanning of light and only the optical image of the optical image formed on the shutter surface that has passed through the moving opening are selectively. A distance gate image pickup device including an image pickup surface that is exposed to light.