JP2019153848A - Imaging apparatus and imaging system - Google Patents

Abstract

To provide an imaging apparatus having an imaging unit including a TDI type sensor that accommodates a vibration.SOLUTION: The imaging apparatus provided on a moving body that moves relative to a subject is provided. The imaging apparatus includes: a light source that irradiates a subject with irradiation light; an imaging unit including a TDI sensor that accumulates charges corresponding to reflected light from the subject and transfers the charges according to an amount of movement of the moving body; a vibration detection unit that detects vibration of the imaging unit due to vibration of the moving body in a charge transfer direction; and a control unit that controls a timing of transferring charges on the basis of a detection result of the vibration in the charge transfer direction detected by the vibration detection unit.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging apparatus and an imaging system.

2. Description of the Related Art Conventionally, an apparatus that installs a TDI camera on a moving body and images structures such as roads, tunnels, and dams is known (see, for example, Patent Document 1).
Patent Document 1 Japanese Patent Application Laid-Open No. 2017-3404

  However, in an imaging apparatus including a conventional TDI camera, the TDI sensor vibrates, and there is a possibility that an image captured due to the influence of the vibration is blurred.

  In order to solve the above-described problem, according to a first aspect of the present invention, there is provided an imaging apparatus provided on a moving body that moves relative to a subject. An imaging apparatus includes a light source that irradiates a subject with irradiation light, an imaging unit that includes a TDI sensor that accumulates charges according to reflected light from the subject and transfers charges according to the amount of movement of the moving body, In the transfer direction, the vibration detection unit that detects the vibration of the imaging unit due to the vibration of the moving body, and the control that controls the timing for transferring the charge based on the detection result of the vibration in the transfer direction of the charge detected by the vibration detection unit A part.

  The vibration detection unit may include a gyro sensor that detects a rotational component of the moving body.

  The vibration detection unit may detect a speed change of the imaging unit according to a speed change of the moving body. The control unit may control the timing of transferring the charge based on the vibration of the imaging unit and the change in speed of the imaging unit detected by the vibration detection unit.

  The imaging device may further include a vibration suppressing unit that suppresses vibration of the imaging unit. The vibration suppression unit may suppress vibration of the imaging surface of the imaging unit in a direction perpendicular to the charge transfer direction.

  The vibration suppressing unit does not have to suppress the fluctuation of the inclination of the charge transfer direction with respect to the vertical direction.

  The vibration suppression unit does not have to suppress vibration in the depth direction of the imaging surface.

  The imaging device may further include a distance measuring unit that measures the distance between the subject and the imaging device. The control unit may further control the timing for transferring the charge using the measurement result of the distance measuring unit.

The distance measuring unit may measure the distance between two or more places in the vertical direction of the subject.
The control unit may control the inclination of the lens of the imaging unit with respect to the subject according to the measurement result of the distance measuring unit.

  The distance measuring unit may measure the distance between two or more places in the vertical direction of the subject. The control unit may control the height position of the lens of the imaging unit with respect to the subject according to the measurement result of the distance measuring unit.

  The distance measuring unit may measure three-dimensional information of each point on the subject. The control unit may control the wavelength of the irradiation light irradiated to each point according to the three-dimensional information of the subject measured by the distance measuring unit.

  In a second aspect of the present invention, a system is provided that includes a moving body that moves relative to a subject and the imaging device described in the first aspect.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

An example of the outline of the imaging system 230 is shown. A more specific configuration example of the imaging system 230 is shown. The moving body 200 in this example is a track. An example of a more specific configuration of the imaging apparatus 100 is shown. It is the conceptual diagram which showed operation | movement of the TDI sensor. 6 is a diagram for explaining a relationship between a distance D between a moving body 200 and a subject 101 and a grid 510. FIG. FIG. 6 is a diagram showing imaging surfaces 610, 612, and 614 recorded when a subject 101 is photographed when a moving body 600 travels on a slope. FIG. 6 is a diagram for explaining a vibration component and a rotation component given to a moving body. 2 shows an exemplary configuration of an imaging apparatus 100. It is a figure for demonstrating the shift of the lens 812. FIG. It is a figure for demonstrating the shift of the lens 812. FIG. It is a figure for demonstrating the shift of the lens 812. FIG. FIG. 10 is a conceptual diagram illustrating a form in which an object 920 is projected onto an imaging plane 910 by a lens 930. FIG. 10 is a conceptual diagram showing a form in which an object 920 is projected on an image plane 910 by a tilted lens 932. FIG. 10 is a conceptual diagram illustrating a form in which an object 920 is projected on an image plane 910 by a reverse tilted lens 934. It is a conceptual diagram explaining the chromatic aberration of a lens. 5 is a graph illustrating different sensor sensitivities for reflected light from a subject 101 depending on the wavelength of the sensor.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 shows an example of an overview of the imaging system 230. The imaging system 230 includes the imaging device 100 and the moving body 200. In one example, the imaging system 230 inspects the subject 101 for defects by imaging the subject 101. For example, the subject 101 is a structure such as an inner wall of a tunnel, a road, and a dam.

  The moving body 200 moves relative to the subject 101. In one example, the moving body 200 is a vehicle such as a truck, or a flying body such as a railway or a drone.

  In this specification, the moving direction of the moving body 200 is the x-axis direction. The y axis is a direction perpendicular to the x axis in the horizontal plane. The z axis is an axis perpendicular to each of the x axis and the y axis, and the x axis, the y axis, and the z axis form a right-handed system. In this example, the case where only the moving body 200 moves will be described, but both the moving body 200 and the subject 101 may move.

  The imaging apparatus 100 is provided on the moving body 200 and moves relative to the subject 101 in the same manner as the moving body 200. The imaging apparatus 100 continuously images the subject 101 while moving relative to the subject 101. Thereby, the imaging apparatus 100 can detect a defect on the surface of the subject 101. The imaging device 100 includes a light source 110, an imaging unit 120, a speed detection unit 130, a vibration detection unit 140, a vibration suppression unit 141, an operation control unit 150, a distance measurement unit 160, and a recording unit 170. .

  The light source 110 irradiates the subject 101 with irradiation light. In one example, the light source 110 includes an incandescent bulb, a fluorescent tube, LED lighting, and a laser. Although it does not limit, it is preferable that the light source 110 has a laser in order to irradiate irradiation light of sufficient light quantity.

  The imaging unit 120 images reflected light from the subject 101 irradiated with the irradiation light. The imaging unit 120 includes a lens 122, an adjustment unit 124, and a TDI sensor 126.

  The lens 122 forms an image of the reflected light from the subject 101 on the imaging surface of the TDI sensor 126. The adjustment unit 124 adjusts the focus position of the lens 122 so that the reflected light received by the lens 122 is clearly imaged by the TDI sensor 126.

  The TDI sensor 126 is a time delay integration (TDI) type imaging device. The TDI sensor 126 images the subject 101 while moving relative to the subject 101. The TDI sensor 126 accumulates charges corresponding to the subject 101 for each pixel by transferring charges according to the relative speed of the subject 101. Thus, the TDI sensor 126 can image the subject 101 with high resolution and high sensitivity by integrating the image of the subject 101.

  The speed detection unit 130 detects a relative movement speed of the imaging device 100 with respect to the subject 101. In one example, when the moving body 200 is a vehicle, the speed detection unit 130 can detect the moving speed of the moving body 200 from the number of rotations of the tire. However, the speed detection unit 130 may detect the moving speed of the moving body 200 using another method such as GPS.

  The vibration detection unit 140 detects a signal corresponding to the vibration of the imaging unit 120. Further, the vibration detection unit 140 may detect a speed change of the moving body 200. The vibration detection unit 140 of this example includes an inertial measurement unit (IMU) that operates as a six-axis sensor. In one example, the vibration detection unit 140 includes a gyro sensor that detects rotational components around three axes (x axis, y axis, and z axis) of the moving body 200. Further, the vibration detection unit 140 may include an acceleration detection unit that detects a speed change and translational vibration of the moving body 200 in the three axes (x-axis, y-axis, and z-axis) directions. The vibration detection unit 140 detects a cumulative measurement result in six axis directions. The vibration detection unit 140 outputs the detected signal to the operation control unit 150.

  The vibration suppression unit 141 mechanically suppresses the vibration of the imaging unit 120 based on the signal detected by the vibration detection unit 140. The vibration suppression unit 141 of this example includes a stabilizer 142 and a damper 144.

  The stabilizer 142 suppresses the rotational component around the x axis of the imaging unit 120. The damper 144 suppresses translational vibration of the imaging unit 120 in the z-axis direction.

  The operation control unit 150 controls the operation of the light source 110. In one example, the operation control unit 150 controls at least one of the irradiation timing of the light source 110 and the wavelength of the irradiation light. When the light source 110 is a laser light source, the operation control unit 150 controls irradiation of the light source 110 by either pulse irradiation or continuous irradiation. For example, the operation control unit 150 matches the pulse irradiation timing of the light source 110 with the exposure timing of the imaging unit 120. Thereby, the imaging unit 120 can easily secure a light amount for imaging the subject 101.

  In addition, the control unit 150 controls the operation of the imaging unit 120. In one example, the operation control unit 150 electronically suppresses vibration of the imaging unit 120 based on the signal detected by the vibration detection unit 140. The operation control unit 150 of this example electronically suppresses vibration of the imaging unit 120 by controlling the exposure timing and charge transfer timing of the TDI sensor 126.

  The distance measuring unit 160 measures the distance D between the imaging device 100 and the subject 101. The distance D between the imaging device 100 and the subject 101 may be used to control the operation of the imaging unit 120. For example, the distance measuring unit 160 is a 3D laser profiler for acquiring three-dimensional information of the subject 101. The three-dimensional information acquired by the distance measuring unit 160 may include information on the depth direction as viewed from the imaging apparatus 100, such as the inclination and unevenness of the subject 101.

  The recording unit 170 records the electrical signal detected by the vibration detection unit 140. The recording unit 170 may transmit the data recorded in the operation control unit 150. Thereby, the operation control unit 150 controls the operations of the light source 110 and the imaging unit 120 based on the data detected by the vibration detection unit 140.

  Here, the imaging apparatus 100 preferably has a sufficiently high resolution and a sufficiently wide dynamic range for imaging the subject 101 in a predetermined imaging environment. In order to satisfy the imaging condition of the imaging apparatus 100, it is preferable to secure a sufficient amount of light.

  Since the imaging apparatus 100 of this example includes the TDI sensor 126, sufficient sensitivity can be ensured by integrating the images of the subject 101 even when the amount of reflected light from the subject 101 is small. . Therefore, even when the subject 101 is the inner wall of the tunnel, it is easy to secure the light amount.

Ensuring a sufficient amount of light is also useful for improving the resolution of the TDI sensor 126. For example, when the pixel width p per pixel of the TDI sensor 126 is halved in order to double the resolution of the TDI sensor 126, the area per pixel on the imaging surface of the TDI sensor 126 (ie, p ² ) Is 1/4 of the original area. Therefore, the amount of reflected light incident on one pixel of the TDI sensor 126 is also ¼.

  In addition, it is preferable that the imaging apparatus 100 has a sufficient depth of field that can cope with the unevenness of the subject 101. The subject 101 is not necessarily directly facing the imaging apparatus 100, and the surface shape thereof may have changes such as unevenness. Therefore, it is preferable that the lens 122 has a depth of field sufficient to absorb the influence of the surface shape of the subject 101. For example, in the case of defect inspection of the subject 101, it is preferable to have a depth of field of 10 cm or more. In this way, it is preferable to realize a high resolution while expanding the depth of focus of the lens 122 and securing a depth of field of a certain level or more.

  The imaging apparatus 100 of this example suppresses vibrations generated by the movement of the moving body 200 by combining both mechanical control and electronic control. The imaging apparatus 100 electronically controls vibrations in the moving direction of the moving body 200 and mechanically controls vibrations in other directions. Thereby, the vibration of the moving direction of the mobile body 200 can be suppressed at a high reaction speed. Further, by eliminating the need for mechanical vibration control in the moving direction of the moving body 200, high rigidity and low cost of the imaging device 100 are realized. Therefore, the imaging apparatus 100 of this example can capture the subject 101 with high sensitivity even when the moving body 200 moves at high speed.

  FIG. 2 shows a more specific configuration example of the imaging system 230. The moving body 200 in this example is a track. The imaging device 100 is placed on the loading platform of the moving body 200.

  The moving body 200 moves along the inner wall of the tunnel that is the subject 101. The imaging apparatus 100 of this example includes three TDI imaging units 120. Thereby, the imaging range 210 can be enlarged in the subject 101.

  Imaging ranges 211a, 211b, and 211c indicate the imaging ranges of the three imaging units 120, respectively. It is only necessary to prepare as many imaging units 120 as the number corresponding to the desired imaging range 210. The number of imaging units 120 is not limited to this. The imaging range 210 moves on the subject 101 as the moving body 200 moves.

  FIG. 3 shows an example of a more specific configuration of the imaging apparatus 100. The imaging apparatus 100 of this example images the inner wall of the tunnel as the subject 101. The imaging apparatus 100 of this example includes two light sources 110 that are disposed on a mount 350 and irradiate irradiation range 310 with irradiation light. The imaging range 312 is an imaging range of the subject 101 by the central imaging unit 120 among the three imaging units 120.

  The imaging unit 120 performs imaging by assigning fine pixels on the imaging range 312. An image captured by the TDI sensor 126 through the lens 122 adjusted by the adjusting unit 124 is sent to the recording unit 170 and recorded.

  The operation control unit 150 includes an imaging control unit 341, a light source control unit 342, a CPU 343, and a clock 344. The imaging control unit 341 controls the adjustment unit 124 of the imaging unit 120. The imaging control unit 341 may control the shift and tilt of the lens 122 corresponding to the tilt of the subject 101. Further, the imaging control unit 341 may control the exposure timing and charge transfer timing of the TDI sensor 126.

  The light source control unit 342 controls the irradiation timing of the irradiation light of the light source 110. For example, the light source control unit 342 controls the operation timing of the light source 110 with respect to the operation timing of the imaging unit 120 according to the time measured by the clock 344. The light source control unit 342 may control the irradiation wavelength of the light source 110 and the like.

  The CPU 343 performs calculation using the measurement results of the speed detection unit 130 and the distance measurement unit 160, the data recorded in the recording unit 170, and the time measurement result of the clock 344. The CPU 343 transmits the calculation result related to the control information to the imaging control unit 341 and the light source control unit 342. The CPU 343 calculates the irradiation timing of the light source 110 and the operation timing of the TDI sensor 126 based on the time measured by the clock 344.

  The distance measuring unit 160 is disposed offset from the imaging unit 120 in the forward direction with respect to the moving direction of the moving body 200. The distance measuring unit 160 of this example is arranged offset from the image capturing unit 120 by the distance d0 in the moving direction of the moving body 200. In this example, the distance measuring unit 160 is arranged to be offset from the imaging unit 120 in the moving direction of the moving body 200, so that the imaging unit 120 captures the distance to the subject 101 captured by the imaging unit 120. It can be measured in advance before doing. The operation control unit 150 can control the operations of the light source 110 and the imaging unit 120 based on data measured in advance by the distance measuring unit 160.

In one example, the offset distance d0 of the distance measuring unit 160 is based on the time required for the operation control unit 150 to perform mechanical control of the imaging unit 120. For example, the time required for mechanical control is the time required for adjusting the lens 122 of the imaging unit 120. The time required for the mechanical control is longer than the time required for electronic control of the TDI sensor 126. Thus, the offset distance d0 of the distance measuring unit 160 preferably satisfies the following equation.
[Equation 1]
(Offset distance d0) ≧ (Reaction time of mechanical control) × (Movement speed of moving body 200)

  However, when the offset distance d0 of the distance measuring unit 160 is increased, when the moving body 200 meanders, the distance D measured by the distance measuring unit 160 and the subject 101 and the image capturing unit when the image capturing unit 120 captures the subject 101 are captured. An error is likely to occur between the actual distance D and 120. Therefore, it is preferable that the offset distance d0 of the distance measuring unit 160 is set to be small within the range of the offset distance d0 obtained from the time required for mechanical control and the moving speed of the moving body 200. For example, the offset distance d0 is 10 cm or more and 1 m or less.

FIG. 4 is a conceptual diagram showing the operation of the TDI sensor 126. The TDI sensor 126 of this example repeats exposure and readout at times t _{1 to} t ₄ .

Time t ₁ is an example of a time corresponding to the exposure timing. At time t ₁ , the imaging surface 430 on the TDI sensor 126 is exposed with reflected light from the subject 101 having the defect 422 on the irradiation surface 420. At the time of exposure, the TDI sensor 126 receives reflected light including the signal 432 from the defect 422 on the imaging surface 430, and the charge 440 corresponding to the signal 432 is accumulated in the TDI sensor 126. The TDI sensor 126 of this example has a predetermined number of stages in each of the x-axis direction and the z-axis direction. The number of stages of the TDI sensor 126 refers to the number of pixels in the x-axis direction or the z-axis direction.

  In the x-axis direction, in the TDI sensor 126 of this example, only four stages are illustrated, but the present invention is not limited to this. For example, the number of stages of the TDI sensor 126 may be 128 stages or 256 stages.

  In the z-axis direction, in the TDI sensor 126 of this example, although only eight stages are illustrated, the present invention is not limited to this. The number of pixels in the z-axis direction of the imaging surface 430 affects the resolution. For example, although the TDI sensor 126 having thousands to tens of thousands of pixels in the z-axis direction can be used, the number of pixels is not limited to these values.

Time t ₂ is an example of a time corresponding to the read timing. Charge transfer 431a is performed at time _{t 2.} Due to the charge transfer 431a, the charge 440 moves by one pixel in the −x axis direction on the imaging surface 430 of the TDI sensor 126. Then, the charge corresponding to the signal 433a at the left end on the imaging surface 430 is read from the charge 440.

Time t ₃ is an example of a time corresponding to the exposure timing. At time t ₃ , the subject 101 is irradiated with irradiation light again, and the imaging surface 430 on the TDI sensor 126 is exposed again with reflected light including the signal 432. A charge 440 corresponding to the signal is accumulated on the capacitive element provided in the TDI sensor 126.

Time t ₄ is an example of a time corresponding to the read timing. Again the charge transfer 431b at time _{t 4} is performed, the charge 440 by the transfer 431b of the charge, in the image pickup surface 430 of the TDI sensor 126, moved by one pixel in the -x axis direction. Then, a charge corresponding to the signal 433b at the left end on the imaging surface 430 is read from the charge 440.

As described above, with respect to signal _{432, t 1, t 3,} ... odd exposure at the timing of the index and t _2, t _4, ... even-numbered subscripts repeated charge transfer at the timing of the character of the As a result, the leftmost signal is read out together with the transfer of charges. Therefore, multistage exposure is performed for each pixel on the imaging surface 430 as many times as the number of stages of the TDI sensor 126, and sufficient light quantity and resolution are ensured for each pixel by the multistage exposure.

The operation control unit 150 controls the exposure timing of the TDI sensor 126. Between the exposure timings t ₁ and t ₃ , the moving body 200 moves by a distance of (moving speed of the moving body 200) × (t ₃ −t ₁ ). Operation control unit _150, as the signal 432 in the period of t 3 -t ₁ is exposed in a state of being moved in the direction of transfer 431a and 432b of the first stage charge on the imaging surface 430, to adjust the exposure timing _{t 3.}

That is, the operation control unit 150 sets the time interval between each exposure after time t ₁ , t _3, and t ₃ according to the moving speed, speed change, and vibration of the moving body 200. Adjust according to change and vibration. Therefore, the influence of the vibration of the moving body 200 in the x-axis direction can be removed by controlling the exposure timing of the TDI sensor 126 without providing a mechanism for suppressing the vibration in the x-axis direction.

  In order to electronically adjust the exposure timing of the TDI sensor 126 performed by the operation control unit 150, it is not necessary to apply a new design to the TDI sensor 126 using a special semiconductor design technique. Adjustment of the exposure timing can be realized only by changing the control method.

  Since the exposure timing is controlled electronically rather than mechanically, a faster reaction speed is realized than mechanical control. Performing the response to the vibration by electronic control leads to a reduction in mechanical operation parts from the entire imaging apparatus 100, and also realizes a mounting mechanism of the imaging apparatus 100 with high rigidity and low cost.

  FIG. 5 is a diagram for explaining the relationship between the distance D between the moving body 200 and the subject 101 and the grid 510. A grid 510 indicates an area of the subject 101 corresponding to the imaging surface 430 captured by the imaging unit 120.

Grid 510, if the distance D between the moving object 200 and the object 101 is changed from the distance _{D 1} to the distance _{D 2,} changes from the grid 510a to the grid 510b. For example, if the distance from the distance _{D 1} to the distance _{D 2} D becomes longer, the size of the grid 510 from the grid 510a to the grid 510b is increased. Therefore, the pixels corresponding to each point of the subject 101 may be shifted due to the change in the distance D.

The operation control unit 150 controls the operations of the light source 110 and the imaging unit 120 so that the pixels corresponding to the respective points of the subject 101 are not shifted by the movement of the moving body 200. For example, even when the distance D increases from the distance D ₁ to the distance D ₂ , the operation control unit 150 causes the light source 110 so that each point of the subject 101 is exposed to the pixel on the corresponding imaging surface 430. And controls the imaging unit 120. Thereby, the imaging apparatus 100 can integrate the charges corresponding to each point of the subject 101 even when the distance D changes.

Further, the operation control unit 150 sets the interval ΔT of the drive pulse transmitted to the imaging unit 120 based on the distance D, the moving speed V of the moving body 200, the speed change ΔV of the moving body 200, and the vibration component of the imaging unit 120. You may control. When there is no influence of vibration of the imaging device 100, the drive pulse interval ΔT is expressed by the following equation.
[Equation 2]
ΔT = (p × D / f) / V

  Here, p is the pixel width of the pixel on the imaging surface 430 of the sensor, f is the focal length of the lens 122, D is the distance between the imaging unit 120 and the subject 101, and V is the moving speed of the moving body 200. Note that the operation control unit 150 may further take into consideration the influence of the speed change ΔV of the moving body 200 and the vibration of the imaging unit 120 in Equation (2).

  FIG. 6 is a diagram illustrating imaging surfaces 610, 612, and 614 recorded when the subject 101 is photographed when the moving body 200 moves on the slope. In FIG. 6, when a track is used as the moving body 200, a diagram in which the imaging unit 120 and the distance measuring unit 160 are provided in the track is illustrated. An imaging surface 610 when the subject 101 is photographed is shown together with pixels.

  The moving body 200 proceeds in the moving direction 630. When the moving body 200 moves up and down the slope, the imaging surface 610 rotates in a direction 640 in which the imaging surface 610 is tilted, and the inclination of the imaging surface 610 changes.

  When the moving body 200 moves on a horizontal surface, the influence of vibration in the moving direction 630 on the imaging surface 610 is electronically suppressed. On the other hand, when the moving body 200 climbs the slope, the vibration suppressing unit 141 does not suppress the rotation in the direction 640 and does not suppress the change in the inclination of the imaging surface. Accordingly, the imaging surface of the moving body 200 that climbs the slope is indicated by the imaging surface 612.

  The vibration suppressing unit 141 does not suppress the fluctuation of the inclination in the direction 640. If the vibration suppression unit 141 stabilizes the imaging surface even in the direction 640, the imaging surface becomes like the imaging surface 614. When the vibration suppression unit 141 stabilizes the image pickup surface like the image pickup surface 614, an image continuously picked up temporally while climbing the slope from the time of running on a horizontal plane is rather perpendicular to the charge transfer direction. The image is blurred. Since the vibration suppressing unit 141 does not suppress a change in the inclination in the direction 640, the subject 101 can be imaged stably.

  FIG. 7A is a diagram for explaining a vibration component and a rotation component given to the moving body 200. The moving body 200 includes a rotation component 711 around the x axis, a rotation component 712 around the y axis, a rotation component 713 around the z axis, an x axis vibration component 721, a y axis vibration component 722, and a z axis vibration. Six components with component 723 are given. The rotation component 711 around the x axis is called a roll. The rotation component 712 around the y axis is called a pitch. The rotation component 713 around the z-axis is called yaw.

  The x-axis vibration component 721 is suppressed by controlling the exposure timing of the TDI sensor 126. The y-axis vibration component 722 is absorbed by the depth of field. However, the y-axis vibration component 722 is not suppressed by the vibration suppression unit 141. Since the surface shape of the subject 101 may originally have unevenness, it is preferable that the influence of the y-axis vibration component 722 corresponds to the depth of field together with the influence of the surface unevenness shape. The z-axis vibration component 723 is mechanically suppressed by the vibration suppression unit 141.

  The rotation component 711 around the x axis is mechanically suppressed by the vibration suppressing unit 141 along with the translational motion in the z axis direction. Since the rotation component 711 and the z-axis vibration component 723 around the x-axis lead to blurring of the image to be captured, it is preferable to appropriately suppress the vibration suppression unit 141.

  When the rotation component 713 around the z-axis is minute vibration, it can be equated with the x-axis vibration component 721. Therefore, similar to the x-axis vibration component 721, this influence is electronically removed by the timing control of the TDI sensor 126.

  The rotation component 712 around the y-axis affects the tilt of the imaging surface 430 of the sensor. No mechanical stabilizer is provided for the inclination of the imaging surface 430 of the sensor. In the moving body 200 that moves on a horizontal plane, such vibration occurs only at 1% or less. When moving on a slope as shown in FIG. 6, the imaging unit 120 is tilted according to the tilt of the entire moving body 200, and the continuity of captured images is maintained.

  The rotational component 712 around the y-axis and the rotational component 713 around the z-axis have different effects on the imaging unit 120 depending on where the imaging unit 120 is provided, and the imaging unit 120 is directed in a direction other than the y-axis direction or the z-axis direction. When done, their influences mix. In the control of the timing of the TDI sensor 126, timing control is appropriately performed at each location where the imaging unit 120 is provided with respect to the influence of the rotation component 712 around the y axis and the rotation component 713 around the z axis.

  FIG. 7B shows an example of the configuration of the imaging apparatus 100. The imaging apparatus 100 includes a six-axis sensor 752 on the stabilizer 142. In addition, the imaging apparatus 100 includes a six-axis sensor 754 provided on the operation control unit 150.

  The six-axis sensor 752 and the six-axis sensor 754 include a rotation component 711 around the x axis, a rotation component 712 around the y axis, a rotation component 713 around the z axis, an x axis vibration component 721, and a y axis vibration component 722. And six components of z-axis vibration component 723 are detected. For example, an x-axis vibration component 721, a y-axis vibration component 722, and a z-axis vibration component 723 are detected by the acceleration detection unit. A gyro sensor detects a rotation component 711 around the x axis, a rotation component 712 around the y axis, and a rotation component 713 around the z axis.

  The six-axis sensor 752 and the six-axis sensor 754 may be provided on either the stabilizer 142 or the mount 350. The six-axis sensor 752 and the six-axis sensor 754 of this example are provided on both the stabilizer 142 and the mount 350. Since the gyro sensor reacts according to the movement, vibrations can be detected more precisely and at high speed by providing both the stabilizer 142 and the mount 350.

  As the stabilizer 142, either a passive stabilizer or an active stabilizer may be used. The passive stabilizer mechanically removes the rotational component only by free rotation. In the passive stabilizer, the rotational axis of the stabilizer 142 is installed perpendicular to the direction of gravity and penetrates the center of gravity of the rigid body. Passive stabilizers have the property of not transmitting rotational motion other than constant speed rotation when the friction of the rotating shaft can be ignored.

  On the other hand, the active stabilizer includes control with a driving force by a motor. Active stabilizers may include spontaneous control by gravity, similar to passive stabilizers. The active stabilizer can more accurately remove vibrations that cannot be removed only by passive control caused by friction of the rotating shaft of the passive stabilizer, deviation from the center of gravity of the rotating shaft, constant-speed rotational motion, and the like.

  FIG. 8A is a diagram for explaining the shift of the lens 812. This figure illustrates a form in which an image is formed on the imaging plane 814 when the subject 101 is photographed using the lens 812.

  The image of the subject 101 is imaged on the imaging surface 814 through the lens 812. In this case, the subject 101 corresponding to the image plane 814 extending with respect to the optical axis passing through the center point of the lens 812 extends symmetrically with respect to the lens 812.

  FIG. 8B is a diagram for explaining the shift of the lens 812. In this example, the lens 822 is inclined with respect to the subject 101. In this mode, an image is formed on the imaging plane 824 when the subject 101 extending farther than the subject 101 is photographed with respect to the optical axis of the lens 822.

  When an image of the subject 101 extending further distal to the subject 101 with respect to the optical axis of the lens 822 is formed on the imaging plane 824, in order to fit the entire subject 101 in the field of view of the lens 822, as shown in FIG. Shooting with an angle of elevation. At this time, the imaging surface 824 forms an image obliquely as shown in FIG. 8B, and an image 826 whose width is tapered toward the upper end of the subject 101 is formed.

  FIG. 8C is a diagram for explaining the shift of the lens 812. In this mode, an image is formed on the imaging plane 834 when the subject 101 extending farther than the subject 101 is photographed with respect to the optical axis of the lens 833 using the lens 832 shifted with respect to the lens 833. .

  The shifted lens 832 has the optical axis shifted upward in the drawing relative to the lens 833. In such a lens, the subject 101 shifted upward in the drawing from the optical axis on the subject surface corresponds to the imaging surface 834 shifted in the downward direction on the drawing, and the subject 101 is looked up at an elevation angle. The image is formed on the image plane 834 without any problem. Further, the shifted lens 832 forms an image of the entire subject 101 on the imaging surface 834 as an equal width image 836 without distorting the image.

  Thus, the lens 122 may be a shiftable lens. In one example, the operation control unit 150 adjusts the shift amount of the lens 122 according to the distance D between the imaging unit 120 and the subject 101.

  A wide area on the subject 101 can be shot by shifting the imaging range while the imaging unit 120 is placed facing the subject 101. This ensures that the horizontal distance on the wall corresponding to one pixel is constant over the entire field of view of the lens. It is preferable that the x-axis direction distance on the subject with respect to the pixel width p of one pixel on the imaging surface 430 of the TDI sensor 126 is uniform over the z-axis direction.

  FIG. 9A is a conceptual diagram illustrating a form in which the subject 101 is photographed on the imaging plane 910 by the lens 930. The depth of field of the lens 930 is the depth of field 940.

  On the image plane 910, the image of the subject 101 is focused on the area where the depth of field 940 and the subject 101 intersect. In this example, only the distance d1 portion of the subject 101 is in focus.

  FIG. 9B is a conceptual diagram showing a form in which the subject 101 is photographed on the imaging plane 910 by the tilted lens 932. The tilted lens 932 has a depth of field of 942.

  An image formed by the subject 101 on the imaging plane 910 is an image focused on a region where the depth of field 942 and the target 920 intersect. In this example, the subject 101 is focused on the area of the distance d2.

  FIG. 9C is a conceptual diagram illustrating a form in which the subject 101 is captured on the image plane 910 by the reversely tilted lens 934. The depth of field of the reverse tilted lens 934 is the depth of field 944.

  On the image plane 910, the image of the subject 101 is focused on the area where the depth of field 944 and the subject 101 intersect. Accordingly, the subject 101 is focused on the area of the distance d3.

  The imaging apparatus 100 can employ a tiltable or reverse tiltable lens as the lens 122. The distance measuring unit 160 measures the distance D between the imaging unit 120 and the subject 101 with the operation control unit 150. The operation control unit 150 controls the lens 122 to tilt or reverse tilt according to the distance D measured by the distance measuring unit 160. As a result, the imaging apparatus 100 can focus on a wide range even when the subject 101 is greatly inclined from the z-axis direction and the inclination cannot be accommodated by the lens shift operation.

  FIG. 10 is a conceptual diagram for explaining the chromatic aberration of the lens. Reflected light is emitted from a target point 1011 of the subject 101. In the drawing, the optical axis passing through the lens center point 1022 is shown in the lens 1020. The reflected light is transmitted through the lens 1020 with refraction at the lens surface. The focal length differs for each wavelength on the point where it intersects the optical axis.

Red light 1012 having wavelength λ _R has a focal point distal from the center point 1022 of the lens on the optical axis. Blue light 1014 having wavelength λ _B has a focal point proximal from the center point 1022 of the lens on the optical axis. As such, the difference in the refractive index depending on the wavelength causes a difference in focal length for each wavelength of the reflected light. Therefore, a difference occurs in the focal length of the white light emitted from the target point 1011. This phenomenon is called axial chromatic aberration. Conversely, in order to obtain a desired focal length can be a light of the irradiated light on the wavelength lambda _D. The optical path of the reflected light 1016 of a wavelength lambda _D is shown in Figure 10.

  When the reflected light from the subject 101 is monochromatic light, if the subject 101 having an unevenness is photographed, an imaging position is generated at a different position on the optical axis on the light receiving side according to the unevenness. When the light source 110 is a multi-wavelength or variable wavelength light source such as a laser or a projector, the distance measuring unit 160 sends a distance between the imaging device 100 and the subject 101 as a signal, and an operation control unit according to the signal 150 uses chromatic aberration to control the wavelength of the light emitted from the light source 110 so that the imaging positions on the light receiving side are equidistant on the optical axis.

  By controlling the wavelength of the irradiation light described above, it is possible to adjust the focus position in the entire visual field corresponding to the case where the wall surface is not a flat surface but has complicated irregularities. Further, when the moving body 200 is a moving body 200 that moves at a high speed, there is a step on the moving surface of the moving body 200, and the distance between the imaging device 100 and the subject 101 fluctuates when passing through the step, and the mechanical focus position. Even when the adjustment is not in time, the subject 101 can be accurately focused.

  When the subject 101 is the inner wall of the tunnel, the inner wall of the tunnel is generally not flat in the direction facing the imaging unit 120, and has a portion that is uneven and has a focus that is out of focus in the field of view of the imaging unit 120 in precise measurement. There is a case. The distance measuring unit 160 does not determine the focus position to a value of one degree of freedom, either a representative value determined from the measurement of the distance near the center in the field of view, or an average value from measurements at a plurality of locations in the field of view. Instead, the distance between two or more places is measured in the vertical direction of the subject so as to cover the entire field of view.

  The distance measuring unit 160 acquires three-dimensional information of the subject 101. The distance measuring unit 160 may store the acquired three-dimensional information in the recording unit 170.

  The operation control unit 150 controls the light source 110 and the adjustment unit 124 according to the three-dimensional information of the subject 101 acquired by the distance measuring unit 160. In one example, the operation control unit 150 controls the wavelength of irradiation light that irradiates each point of the subject 101. For example, the operation control unit 150 irradiates the light source 110 having a plurality of wavelengths or variable wavelengths with irradiation light having an appropriate wavelength in each region of the subject 101. The operation control unit 150 may control the adjustment unit 124 by adjusting the height position (shift amount) of the lens 122 and the tilt (tilt amount) of the lens 122.

FIG. 11 is a graph illustrating different sensor sensitivities depending on the wavelength of the sensor with respect to the reflected light from the subject 101. The TDI sensor 126 may be a monochrome sensor. Monochrome sensor has a sensitivity f (λ ₂₎ with respect to sensitivity f (lambda _1), the wavelength lambda ₂ with respect to the wavelength lambda _1.

  In such a case, f (λ) × (intensity) can be made constant by adjusting the intensity of the irradiation light having the wavelength λ according to f (λ). The influence of the wavelength characteristic can be compensated for by adjusting the intensity of the light emitted from the light source 110 with respect to each wavelength in accordance with the wavelength characteristic in the sensitivity of the TDI sensor 126. For example, the light source 110 increases the intensity of irradiation light at the wavelength λ where the sensitivity of the TDI sensor 126 is low, compared to the wavelength λ where the sensitivity of the TDI sensor 126 is high.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 100 ... Imaging device, 101 ... Subject, 110 ... Light source, 120 ... Imaging part, 122 ... Lens, 124 ... Adjustment part, 126 ... TDI sensor, 130 ... Speed detection unit 140 ... vibration detection unit 141 ... vibration suppression unit 142 ... stabilizer 144 ... damper 150 ... operation control unit 160 ... ranging unit 170 ..Recording unit, 200 ... moving body, 210 ... imaging range, 211a, 211b, 211c ... imaging range, 230 ... system, 310 ... irradiation range, 312 ... imaging range, 341: Imaging control unit, 342 ... Light source control unit, 343 ... CPU, 344 ... Clock, 350 ... Mount, 420 ... Irradiation surface, 422 ... Defect, 430 ... -Imaging surface, 431a, 431 ... Charge transfer, 432 ... Signal, 433a ... Left edge signal, 433b ... Left edge signal, 440 ... Charge, 510a, 510b ... Grid, 610, 612, 614 ... Imaging surface, 630... Moving direction, 640... Direction, 711... Rotation component around the x axis, 712... Rotation component around the y axis, 713. 721 ... x-axis vibration component, 722 ... y-axis vibration component, 723 ... z-axis vibration component, 752 ... six-axis sensor, 754 ... six-axis sensor, 812 ... lens, 814 ... imaging plane, 822 ... lens, 824 ... imaging plane, 826 ... tapered image, 832 ... shifted lens, 833 ... lens, 834 ... imaging Surface, 836 ... Equal width image, 910 ... Image plane, 920 ... object, 930 ... lens, 932 ... tilted lens, 934 ... reverse tilted lens, 940 ... depth of field, 942 ... subject Depth of field, 944 ... Depth of field, 1011 ... Target point, 1012 ... Red light, 1014 ... Blue light, 1016 ... Reflected light of wavelength [lambda] _D , 1020 ... Lens, 1022... Center point of the lens

Claims (11)

An imaging device provided on a moving body that moves relative to a subject,
A light source for irradiating the subject with irradiation light;
An imaging unit including a TDI type sensor that accumulates electric charge according to reflected light from the subject and transfers the electric charge according to a moving amount of the moving body;
A vibration detection unit that detects vibration of the imaging unit due to vibration of the moving body in the charge transfer direction;
An imaging apparatus comprising: a control unit that controls timing of transferring the charge based on a detection result of vibration in the transfer direction of the charge detected by the vibration detection unit.   The imaging apparatus according to claim 1, wherein the vibration detection unit includes a gyro sensor that detects a rotational component of the moving body. The vibration detection unit detects a speed change of the imaging unit according to a speed change of the moving body,
The control unit controls the timing of transferring the charge based on the vibration of the imaging unit and the speed change of the imaging unit detected by the vibration detection unit.
The imaging device according to claim 1 or 2. A vibration suppression unit for suppressing vibration of the imaging unit;
4. The imaging apparatus according to claim 1, wherein the vibration suppression unit suppresses vibration of an imaging surface of the imaging unit in a direction perpendicular to the charge transfer direction. 5.   The imaging apparatus according to claim 4, wherein the vibration suppressing unit does not suppress a change in inclination of the charge transfer direction with respect to a vertical direction.   The imaging apparatus according to claim 4, wherein the vibration suppressing unit does not suppress vibration in the depth direction of the imaging surface. A distance measuring unit for measuring a distance between the subject and the imaging device;
The imaging device according to claim 1, wherein the control unit further controls a timing of transferring the charge by further using a measurement result of the distance measuring unit. The distance measuring unit measures the distance between two or more places in the vertical direction of the subject,
The imaging device according to claim 7, wherein the control unit controls an inclination of a lens of the imaging unit with respect to the subject according to a measurement result of the distance measuring unit. The distance measuring unit measures the distance between two or more places in the vertical direction of the subject,
The imaging device according to claim 7 or 8, wherein the control unit controls a height position of a lens of the imaging unit with respect to the subject according to a measurement result of the distance measuring unit. The distance measuring unit measures three-dimensional information of each point on the subject,
The said control part controls the wavelength of the said irradiation light irradiated to each said point according to the three-dimensional information of the said object which the said ranging part measured, The any one of Claim 7 to 9 Imaging device. A moving body that moves relative to the subject;
An imaging system comprising: the imaging device according to any one of claims 1 to 10.

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