JP7585683B2 - Photographing device, photographing system, moving object, and program - Google Patents

Description

The present invention relates to an imaging device, an imaging system, a moving object, and a program.

Photographing devices for photographing an object have been known for some time. In order to prevent condensation on the photographing lens included in the photographing device, a configuration has been disclosed in which a lens holder made of a material with high thermal conductivity, such as aluminum, is brought into contact with a substrate on which an imaging means, such as an image sensor, is provided, thereby transferring heat from the imaging means to heat the photographing lens (see, for example, Patent Document 1).

However, the configuration described in Patent Document 1 does not efficiently heat the photographing lens, and condensation may not be sufficiently prevented.

The objective of the present invention is to provide an imaging device that can efficiently heat the imaging lens.

An image capturing device according to one aspect of the present invention is an image capturing device for capturing an image of an object, and includes an image capturing lens, an image capturing means for capturing an image of the object using the image capturing lens, an illumination means for illuminating an area captured by the image capturing device with illumination light, and a heating means for heating the image capturing lens with energy based on the illumination light, wherein the heating means includes an illumination deflection member for deflecting at least a portion of the illumination light toward the image capturing lens, and the image capturing lens is heated by the energy of light irradiated to the image capturing lens using the illumination deflection member.

The present invention allows the imaging lens to be heated efficiently.

1 is a perspective view showing an example of the configuration of an imaging system according to an embodiment; FIG. 2 is a perspective view showing a configuration example of a camera unit according to an embodiment. FIG. 2 is a perspective view illustrating a configuration example of a lighting unit according to an embodiment. FIG. 2 is a block diagram showing an example of the hardware configuration of the imaging system according to the embodiment. 1A and 1B are diagrams for explaining photography when the distance from the vehicle to the tunnel wall is short, in which (a) shows the vehicle as viewed from the direction of travel, and (b) shows the vehicle traveling inside the tunnel. 1A and 1B are diagrams for explaining photography when the distance from the vehicle to the tunnel wall is long, in which (a) shows the vehicle as viewed from the direction of travel, and (b) shows the vehicle traveling inside the tunnel. 1A and 1B are diagrams showing the influence of changes in position/orientation of a camera unit and a lighting unit, where FIG. 1A shows a case where there is no change in position/orientation, and FIG. 1B shows a case where there is a change in position/orientation. 5A to 5C are diagrams illustrating configuration examples of a guide shaft and a guide shaft holding member. 13 is a diagram showing the relationship between the shooting area and the illumination area when inclined relative to the wall of a tunnel. FIG. FIG. 4 is a diagram showing a configuration example of an index plunger. 11A and 11B are diagrams illustrating an example of the effect of tilting the illumination direction with respect to the shooting direction. 1A and 1B are diagrams showing the relationship between the inclination of the illumination light and the photographing light, the illumination light distribution angle, and the lighting area, in which (a) shows the relationship between the camera unit, the lighting unit, and the tunnel wall, and (b) shows the case where the vehicle moves away from the tunnel wall with the photographing area and the lighting area overlapping. 10A and 10B are diagrams showing the relationship between the inclination of the illumination light and the shooting light, the illumination light distribution angle, and the lighting area, in which (c) shows the case where the shooting area and the lighting area overlap and the vehicle approaches the wall of a tunnel, and (d) shows an example where the shooting light is tilted with respect to the illumination light. 1A and 1B are diagrams illustrating an example of a relationship between a meandering vehicle, a photographed area, and an illuminated area. 5 is a flowchart showing an example of the operation of the imaging system according to the embodiment. 1 is a perspective view showing an example of the configuration of an imaging system according to a first embodiment. FIG. 2 is a perspective view showing the imaging system in a state where the exterior cover is closed. 3 is a perspective view showing an example of the configuration of an illumination reflecting member according to the first embodiment; FIG. 3A to 3C are side views illustrating an example of the configuration of an illumination reflecting member according to the first embodiment. 4A to 4C are diagrams illustrating examples of the arrangement of components within an exterior cover.

Below, a description will be given of an embodiment of the invention with reference to the drawings. In each drawing, the same components are given the same reference numerals, and duplicate descriptions will be omitted as appropriate.

The embodiments shown below are illustrative of an imaging device for embodying the technical ideas of the present invention, and the present invention is not limited to the embodiments shown below. Unless otherwise specified, the shapes of the components described below, their relative positions, parameter values, etc. are intended as examples, and are not intended to limit the scope of the present invention. Furthermore, the sizes and positional relationships of the components shown in the drawings may be exaggerated for clarity of explanation.

The imaging device according to the embodiment is an imaging device for imaging an object, and includes an imaging lens, imaging means for capturing an image of the object through the imaging lens, and heating means for heating the imaging lens with energy based on illumination light capable of illuminating the imaging range of the imaging device.

For example, the heating means includes an illumination deflection member that deflects at least a portion of the illumination light toward the photographing lens, and heats the photographing lens with the energy of the light irradiated onto the photographing lens using the illumination deflection member. By heating the photographing lens with the energy of the illumination light, the photographing lens can be heated more efficiently than when heat is used from an imaging means such as a CCD (Charge Coupled Device).

In the terms used in the description of the embodiments, a structure refers to a structure that is made up of a plurality of materials or members and that can support a weight. Examples of structures include roads, tunnels, buildings, dams, and levees. A mobile object refers to an object that can move. Examples of mobile objects include vehicles such as automobiles and trains, and flying objects such as drones. In the embodiments, a captured image includes a still image, a video, and a video.

The following describes an embodiment using an imaging system including an imaging device according to the embodiment as an example.

[Embodiment]
<Overall configuration of the imaging system>
1 is a perspective view illustrating an example of a configuration of an imaging system according to an embodiment. The imaging system 100 includes a slide unit 200, a camera unit 300, and an illumination unit 400.

The camera unit 300 captures the tunnel walls, and the lighting unit 400 shines light onto the tunnel walls for capture by the camera unit 300.

The slide unit 200 is a member for sliding the camera unit 300 and the lighting unit 400 in the direction of the thick arrow in FIG. 1. The camera unit 300 and the lighting unit 400 can change their positions in the direction of the thick arrow in FIG. 1 by using the slide unit 200.

The slide unit 200 also includes rails 210 and 220, a base 230, a guide shaft 240, guide shaft holding members 251 and 252, and frames 261 and 262.

The camera unit 300 can change its position in the direction of the thick arrow in FIG. 1 by sliding on a rail 210 fixed to a frame 261. Similarly, the lighting unit 400 can change its position in the direction of the thick arrow in FIG. 1 by sliding on a rail 220 fixed to a frame 262.

Rails 210 and 220 are fixed to frames 261 and 262, respectively, so that the rail axes are approximately parallel. Base 230 is fixed to frames 261 and 262, connecting them and serving as the base of imaging system 100.

The guide shaft 240 is a member used to slide the camera unit 300 and the lighting unit 400 with stable precision, and is a metal round bar or the like. The longitudinal direction of the round bar is set so as to follow the sliding direction of the camera unit 300 and the lighting unit 400.

The guide shaft 240 is passed through and held in through holes provided in the guide shaft holding members 251 and 252 that hold the guide shaft 240. The structure and function of the guide shaft 240 and its surrounding members will be described in detail separately.

Here, FIG. 1 shows a configuration in which the slide unit 200 slides both the camera unit 300 and the lighting unit 400, but this is not limited to the configuration. A configuration in which the unit that slides the camera unit 300 and the unit that slides the lighting unit 400 are separate may also be used.

The imaging system 100 is attached to the roof of the vehicle or the like so that the sliding direction of the camera unit 300 and the lighting unit 400 intersects with the traveling direction of the vehicle. In other words, the direction of the thick arrow in FIG. 1 intersects with the traveling direction of the vehicle to which the imaging system 100 is attached. By attaching them in this manner, the positions of the camera unit 300 and the lighting unit 400 can be changed within a plane that intersects with the traveling direction of the vehicle.

The part of the vehicle to which the imaging system 100 is attached is not limited to the roof. It may be the bonnet at the front or rear of the vehicle, or the bed if the vehicle is a truck. When attaching the imaging system 100 to the roof of a vehicle, it may be done using hook parts, similar to a ski carrier for a vehicle.

<Camera unit configuration>
Next, FIG. 2 is a perspective view illustrating an example of the configuration of the camera unit 300 according to the embodiment.

The camera unit 300 has a base plate 310, rail connection parts 321 and 322, cameras 331 to 334, shaft connection parts 341 and 342, and an index plunger 350.

The rail connection parts 321 and 322 are members for connecting the base plate 310 and the rail 210. The rail connection parts 321 and 322 have a U-shaped cross section in a direction perpendicular to the rail axis. When the rail 210 is a double-headed rail, the rail connection parts 321 and 322 are connected to the rail 210 by placing the U-shaped part over one of the heads of the double-headed rail.

The rail connection parts 321 and 322 have the same shape and connect to the rail 210 at two different positions in the axial direction of the rail. By fixing the base plate 310 to the rail connection parts 321 and 322, the camera unit 300 becomes slidable in the direction of the rail axis (the direction of the thick arrow in Figure 1).

Cameras 331 to 334 are fixed to the flat surface of base plate 310. Here, camera 331 has lens 331-1 and line CCD (Charge Coupled Device) 331-2. Lens 331-1 forms an image of a subject located in the optical axis direction of lens 331-1 on the imaging surface of line CCD 331-2. Line CCD 331-2 captures the image of the subject that has been formed.

Aperture 331-1a (see Figure 4) is also provided inside lens 331-1. Aperture 331-1a is an iris diaphragm with aperture blades, and is an aperture with a variable diameter. The diameter of the aperture can be changed by connecting a drive source such as a motor to the aperture blades and driving the motor based on a control signal. This changes the amount of light passing through lens 331-1, and changes the brightness of the image of the subject formed by lens 331-1.

Line CCD 331-2 is a CCD in which pixels are arranged one-dimensionally (in a line), and in this embodiment, camera 331 is fixed to base plate 310 so that the direction in which the pixels of line CCD 331-2 are arranged intersects with the vehicle's traveling direction. Cameras 332 to 334 also have a similar configuration to camera 331, but as they are similar to those described above, a description of them will be omitted.

The cross section of the tunnel that intersects with the direction of travel of the vehicle has a semicircular shape. In accordance with this, the cameras 331 to 334 are arranged radially so that the optical axis of each of the lenses intersects with the wall of the tunnel, as shown in FIG. 2. In other words, the cameras 331 to 334 are arranged radially on the flat surface of the base plate 310 so that each faces the wall of the tunnel.

By stitching together the line images captured by cameras 331 to 334 in the direction of the camera arrangement, a line image of the tunnel wall can be captured that follows the shape of the tunnel. Then, by continuously capturing the line images at a specified time interval while the vehicle is traveling and stitching together the captured line images in a direction perpendicular to the pixel arrangement direction of the line image, an area image (two-dimensional image) of the tunnel wall can be obtained. The specified time interval is the period for capturing line images by the line CCD, etc.

In the above example, the number of cameras is four, but this is not limiting. The number of cameras may be increased or decreased depending on conditions such as the size of the tunnel. In addition, the imaging magnification, field of view, F-number, etc. of lens 331-1 may be determined according to the conditions to be photographed.

In addition, while the above description shows an example in which the camera 331 is equipped with a line CCD, the present invention is not limited to this, and the camera 331 may be equipped with an area CCD in which pixels are arranged two-dimensionally. Furthermore, a CMOS (Complementary Metal-Oxide-Semiconductor) or the like may be used instead of a CCD.

On the other hand, the shaft connectors 341 and 342 are members for connecting to the guide shaft 240. The index plunger 350 is a member for fixing the camera unit 300 at a desired position in the sliding direction. The configurations and functions of the shaft connectors 341 and 342 and the index plunger 350 will be described in detail separately.

<Lighting unit configuration>
Next, FIG. 3 is a perspective view illustrating an example of the configuration of an illumination unit 400 according to an embodiment.

The lighting unit 400 has a base plate 410, a rail connection part, lighting light source parts 431 to 436, shaft coupling parts 441 and 442, and an index plunger 450. The relationship between the rail connection part and the rail 220 is similar to the relationship between the rail connection parts 321 and 322 and the rail 210 described above.

The illumination light source units 431 to 436 are fixed to the flat surface of the base plate 410. The illumination light source unit 431 has a lens 431-1 and a light source 431-2.

The light source 431-2 illuminates an object located in the optical axis direction of the lens 431-1 through the lens 431-1. In addition, an aperture 431-1a is provided inside the lens 431-1 (see Figure 4).

The aperture 431-1a is an aperture with a variable diameter, and by changing the diameter of the aperture, the amount of light (brightness) of the illumination light illuminated by the lens 431-1 can be changed. A metal halide light or an LED (Light Emitting Diode) can be used as the light source 431-2. Note that the illumination light source units 432 to 436 have the same configuration as the illumination light source unit 431, but as they are similar to the above, a description thereof will be omitted.

As mentioned above, the cross section of the tunnel that intersects with the vehicle's travel direction is semicircular. Accordingly, the illumination light source units 431-436 are arranged radially so that the optical axis of each lens intersects with the tunnel wall, as shown in FIG. 3. In other words, the illumination light source units 431-436 are arranged radially on the flat surface of the base plate 410 so as to face the tunnel wall. The illumination unit 400 can illuminate the tunnel wall with linear light that intersects with the vehicle's travel direction (the direction in which the pixels of the line CCD are arranged).

In the above, an example was described in which the number of illumination light source units was six, but this is not limited to six and may be increased or decreased. The number of illumination light source units does not necessarily have to match the number of cameras, and may be determined according to conditions such as brightness. Furthermore, the lens angle of view and F-number may also be determined according to the conditions under which shooting is desired.

In addition, in the above description, the positions of the illumination light source units 431 to 436 are shifted slightly forward and backward along the optical axis of the lens, but this is to prevent physical interference between the illumination light source units.

On the other hand, the shaft connectors 441 and 442 are members for connecting to the guide shaft 240. The index plunger 450 is a member for fixing the lighting unit 400 at a desired position in the sliding direction. The configurations and functions of the shaft connectors 441 and 442 and the index plunger 450 will be described in detail separately.

<Hardware configuration of the imaging system>
4 is a block diagram showing an example of a hardware configuration of the imaging system 100. The imaging system 100 includes a camera unit 300, a lighting unit 400, a sensor control board 110, a time of flight (TOF) sensor 141, an inertial measurement unit (IMU) 170, a speedometer/travel distance meter 171, and an operation unit 118.

The TOF sensor 141 detects the distance from the wall of the tunnel 600 to the TOF sensor 141, and can detect the distance from the wall of the tunnel 600 to the imaging system 100.

More specifically, the TOF sensor 141 irradiates the wall of the tunnel 600 with light, and detects the distance to the wall of the tunnel 600 based on the time it takes for the reflected light to be received. If the TOF sensor 141 uses an area sensor as the light receiving element, it is possible to obtain a two-dimensional contour image in which the display color changes depending on the distance.

The IMU 170 measures the angles/angular velocities and accelerations of the three axes that govern the movement of the vehicle 500, and the speedometer/distance traveled meter 171 can measure the speed/distance traveled of the vehicle 500.

The data measured by the IMU 170 and the speedometer/travel distance meter 171 is output to the HDD 114 via the sensor control board 110 and stored there, and is later used to geometrically correct the size, inclination, etc. of the image of the wall surface through image processing.

Camera unit 300 includes lenses 331-1, 332-1, 333-1, and 334-1, and line CCDs 331-2, 332-2, 333-2, and 334-2. Lens 331-1 includes aperture 331-1a, lens 332-1 includes aperture 332-1a, lens 333-1 includes aperture 333-1a, and lens 334-1 includes aperture 334-1a. However, in order to simplify the drawing, only lens 331-1, aperture 331-1a, and line CCD 331-2 are shown in FIG. 4, and the other lenses, apertures, and line CCDs are not shown.

The lighting unit 400 includes lenses 431-1, 432-1, 433-1, 434-1, 435-1, and 436-1, and light sources 431-2, 432-2, 433-2, 434-2, 435-2, and 436-2. Lens 431-1 includes aperture 431-1a, lens 432-1 includes aperture 432-1a, lens 433-1 includes aperture 433-1a, lens 434-1 includes aperture 434-1a, lens 435-1 includes aperture 435-1a, and lens 436-1 includes aperture 436-1a. However, in order to simplify the drawing, only lens 431-1, aperture 431-1a, and light source 431-2 are shown in FIG. 4, and the other lenses, apertures, and light sources are omitted.

The sensor control board 110 has a CPU (Central Processing Unit) 111, a ROM (Read Only Memory) 112, a RAM (Random Access Memory) 113, a HDD (Hard Disk Drive) 114, an external I/F (Interface) 115, and a buzzer 116, all of which are electrically connected to each other via a system bus 117. Here, the sensor control board 110 is an example of a computer.

The ROM 112 stores various programs, data, and various setting information, while the RAM 113 temporarily holds programs and data. The CPU 111 reads out the programs, data, and setting information from the ROM 112, etc. onto the RAM 113 and executes the processing, thereby controlling the entire imaging system 100 and processing image data. Here, image data processing refers to processing such as joining together line images captured by the cameras 331-334, and joining together line images captured continuously by the cameras 331-334 at predetermined time intervals while the vehicle is traveling, in the direction of vehicle travel. The CPU 111 can also realize various functions that will be described in detail separately using Figures 15 and 18.

Note that some or all of the control, image data processing, and various functions performed by the CPU 111 may be realized using a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC).

The HDD 114 stores image data input from the camera unit 300, sensor data input from the TOF sensor 141, the IMU 170, and the speedometer/travel distance meter 171, etc. The HDD 114 may be provided outside the sensor control board.

The external I/F 115 provides a user interface function that allows the user to operate the imaging system 100, and an interface function that allows the imaging system 100 to exchange data and signals with external devices such as a PC (Personal Computer).

The buzzer 116 emits a beep to alert the user of a warning.

The sensor control board 110 may be connected to an external device such as a PC (Personal Computer) via the external I/F 115, allowing data such as image data to be sent and received between the sensor control board 110 and the external device.

The operation unit 118 is a user interface for operating the imaging system 100. The operation unit 118 includes an input unit such as a mouse and a keyboard, and a display unit such as a display. A notebook PC or the like can be used as the operation unit 118.

When photographing, for example, the camera unit 300, lighting unit 400, TOF sensor 141, IMU 170, speedometer/travel distance meter 171, and sensor control board 110 are installed on the roof of the vehicle. The operation unit 118 is provided inside the vehicle and is operated by an operator or the like. The operator is a person who operates the photographing system 100 to perform photographing work. The operator may be the driver of the vehicle or a person other than the driver of the vehicle. Furthermore, when photographing is performed with an autonomous vehicle or the like, a device or equipment may take on the role of the operator instead of a person.

While the vehicle is traveling, the operator can operate the recording start button and stop button on the operation unit 118 to instruct the camera to start and stop recording, and take pictures.

<Shooting method, effects, etc.>
Next, a photographing method and effects of the photographing system 100 according to the embodiment will be described.

In the photography system 100, the camera unit 300 and the lighting unit 400 slide using the slide unit 200, and are fixed at two positions determined based on the length of a specified road structure in a direction intersecting the vehicle's traveling direction.

The length of a given road structure is the width of the sidewalk in a direction intersecting the direction of vehicle travel.

Here, a sidewalk is a road for pedestrians to walk on, and refers to a part of a road that is attached to a roadway or the like and is structurally partitioned for pedestrians to walk on. The width of a sidewalk varies depending on the number of pedestrians passing by, but is generally around 1.5 to 3 meters.

If the width of the sidewalk is 1.5 m, the distance between the two positions determined based on the sidewalk width may be set to 1.5 m. Alternatively, if the width of the sidewalk is 3 m, which exceeds the width of the vehicle, the distance between the two positions determined based on the sidewalk width may be set as the maximum width of the vehicle.

In addition, if there is an inspection path or roadside strip in addition to the sidewalk, the distance between two positions determined based on the width of the sidewalk may be determined as the difference between the width of the sidewalk and the width of the inspection path or roadside strip.

When acquiring images at two positions, first, the camera unit 300 and the lighting unit 400 are fixed to one of two positions determined based on the width of the sidewalk in a direction intersecting the vehicle's traveling direction, and an area image of the tunnel wall in the desired area is acquired. Next, the camera unit 300 and the lighting unit 400 are fixed to the other of the two positions, and an area image of the tunnel wall in the desired area is acquired.

The method of photographing the wall of the tunnel 600 from two positions will be described in detail below with reference to Figures 5 and 6. Figure 5 is a diagram for explaining an example of how to photograph the wall of the tunnel 600 when the distance from the photographing system 100 to the wall of the tunnel 600 is short, where (a) is a diagram of the vehicle 500 as seen from the direction of travel, and (b) is a diagram showing the vehicle 500 traveling inside the tunnel 600.

In FIG. 5(a), the imaging system 100 is fixed on the roof of a vehicle 500. The camera unit 300 and the lighting unit 400 are slid to the right end of the slide unit 200 in the direction of travel and are fixed to the slide unit 200 by index plungers 350 and 450, respectively.

On the other hand, in FIG. 5(b), lane 710 is on the left side of the center of road 700, and lane 720 is on the right side. Vehicle 500 is traveling in lane 720 toward the front of the page.

In this example, there is a sidewalk 730 on the lane 710 side (the oncoming lane of the vehicle 500). There is no sidewalk on the lane 720 side, so the vehicle 500 is traveling closer to the wall of the tunnel 600 on the vehicle 500 side than if there was a sidewalk.

The camera unit 300 and the lighting unit 400 are located at the right end of the slide unit 200 in the direction of travel, that is, away from the wall of the tunnel 600 on the vehicle 500 side. Hereinafter, the position of the camera unit 300 and the lighting unit 400 in this case will be referred to as position A.

The dashed line 100A in FIG. 5(b) represents the range of photography by the photography system 100. In other words, the photography system 100 photographs an area 600A (area shown by a thick line) of the tunnel wall 600 within the photography range shown by the dashed line 100A. As shown by the thick line, in this embodiment, photography is performed up to the boundary between the tunnel wall (lining) and the ground.

By photographing using the photographing system 100 while the vehicle 500 is traveling, the right half of the wall surface in FIG. 5(b) is photographed from the entrance to the exit of the tunnel 600.

On the other hand, FIG. 6 is a diagram explaining an example of how photography occurs when the distance from the photography system to the tunnel wall is long, where (a) is a diagram of the vehicle 500 viewed from the direction of travel, and (b) is a diagram showing the vehicle 500 traveling inside the tunnel 600. Note that explanations of parts that overlap with FIG. 5 will be omitted, and differences will be explained.

In FIG. 6, the camera unit 300 and the lighting unit 400 are slid to the left end of the slide unit 200 in the travel direction and are fixed to the slide unit 200 by index plungers 350 and 450, respectively.

On the other hand, in FIG. 6(b), the vehicle 500 is traveling in lane 710 toward the front of the page.

In this example, there is a sidewalk 730 on the side of lane 710 (the lane in which vehicle 500 is traveling). In other words, vehicle 500 is traveling in the opposite direction on the lane opposite to the case of FIG. 5(b). In this case, vehicle 500 will be traveling farther from the wall of tunnel 600 on the vehicle 500 side than if there was no sidewalk on the traveling lane side.

The camera unit 300 and the lighting unit 400 are located at the left end of the slide unit 200 in the direction of travel, i.e., close to the wall of the tunnel 600 on the vehicle 500 side. The position of the camera unit 300 and the lighting unit 400 in this case will be referred to as position B hereafter.

Dotted line 100B in FIG. 6(b) represents the range of photography by photography system 100. In other words, photography system 100 photographs area 600B (area shown by a thick line) of the tunnel wall 600 within the photography range shown by dashed line 100B. As shown by the thick line, in this embodiment, photography is performed up to the boundary between the tunnel wall (lining) and the ground.

By photographing using the photographing system 100 while the vehicle 500 is traveling, the right half of the wall surface in FIG. 6(b) is photographed from the entrance to the exit of the tunnel 600.

By stitching together the image of the wall surface captured in the state of Figure 5 and the image of the wall surface captured in the state of Figure 6, it is possible to obtain images of the entire wall surface from the entrance to the exit of tunnel 600.

It is desirable that the images captured by each camera of the camera unit 300 have overlapping shooting areas. Also, in order to create a single development image by stitching the images together, it is desirable to capture the image of the side without a sidewalk in FIG. 5 and the image of the side with a sidewalk in FIG. 6 so that the ceiling portions overlap. In other words, when capturing images of the wall of the tunnel 600 on the way there and back, it is desirable to capture the shooting areas on the way there and back so that they overlap in a direction that intersects with the traveling direction of the vehicle 500 so that no areas of the wall of the tunnel 600 are not captured.

According to the embodiment, the distance from the wall on the vehicle 500 side to the imaging system 100, i.e., the subject distance, can be easily kept approximately constant by simply switching and fixing the camera unit 300 and the lighting unit 400 to positions A and B depending on whether or not there is a sidewalk. As a result, it is possible to capture images with common imaging conditions such as the focus state, imaging magnification, and lighting brightness, regardless of whether or not there is a sidewalk. In addition, since the walls of the right and left halves of the tunnel can be captured under common imaging conditions, image processing to join the two can be easily performed.

This makes it possible to properly photograph the tunnel walls without having to adjust the camera focus or measure the cross-sectional shape of the object.

In addition to the above, the following effects can also be obtained. For example, if the focus of the camera is adjusted while the vehicle is moving, the adjustment mechanism may break down due to vibrations caused by the vehicle moving or irregular movements such as sudden braking or acceleration.

In addition, if the adjustment mechanism uses a cam mechanism that employs a cam groove and cam follower, the vibrations caused by the vehicle moving can cause the cam follower to gradually move along the cam groove, changing the focus state. Furthermore, if dust from inside the tunnel gets inside the mechanism, it can cause malfunctions.

According to the embodiment, the camera focus and other adjustments are not performed while the vehicle is traveling, which reduces the possibility of these malfunctions. In addition, the slide mechanism is simple, which also has the effect of reducing device costs. Furthermore, since there is no need to perform complex image processing such as detecting the contrast of the subject's texture to adjust the focus, calculation costs can be reduced.

Furthermore, when traveling through a dark tunnel with few features, it is difficult to detect contrast in the first place, and performing contrast detection with sufficient accuracy requires a highly sensitive and expensive imaging element. According to the embodiment, it is possible to reduce such technical difficulty and the cost of the imaging element.

In addition, when a line image sensor is used in the camera unit, only one line of image can be obtained, making it difficult to adjust the focus using the captured image. According to the embodiment, the captured image is not used for focus adjustment, so a line image sensor can be used in the camera unit. This enables shooting with good lighting efficiency, as described below.

In addition to the above, the following effects can also be obtained. For example, assume that the camera unit 300 and the lighting unit 400 are placed at a position relatively offset from the center of the tunnel 600 and an image is taken. Here, the center of the tunnel 600 refers to approximately the center of the semicircle in the semicircular cross-sectional shape of the tunnel 600.

In this case, the difference in conditions such as the magnification ratio becomes large between the image of the wall surface near the ceiling of the tunnel 600 (image acquired by camera 331 in FIG. 2) and the image of the wall surface near the ground of the tunnel 600 (image acquired by camera 334 in FIG. 2). As a result, problems such as a large difference in image resolution between the ceiling and ground of the tunnel 600 occur.

To eliminate such problems, there is a method of photographing the tunnel walls while driving a vehicle in the center of the road, ignoring lanes, so that the distance to the tunnel walls remains approximately constant (see, for example, JP 2011-095222).

However, this method poses the risk of colliding with an oncoming vehicle when taking pictures, so it is inconvenient because it must be done at night when there is little traffic or when the road is closed. Also, if there is a median strip on the road inside the tunnel, it is impossible to take pictures using the above method in the first place.

In contrast, according to the embodiment, the camera unit 300 and the lighting unit 400 can be brought closer to the center of the tunnel 600 whether the vehicle 500 is close to or far from the wall of the tunnel 600, so that the difference in shooting conditions between different areas of the tunnel can be suppressed. Therefore, without stopping the vehicle from passing through, while driving in the original lane, shooting can be performed while suppressing problems such as different image resolutions near the ceiling and near the ground of the tunnel 600.

In the embodiment, an example is shown in which the position of the slide unit 200 is changed in the direction of the thick arrow in FIG. 1, but the present invention is not limited to this. The position of the slide unit 200 may be changed in any direction within a plane that intersects with the vehicle's traveling direction.

In the embodiment, the camera unit 300 and the lighting unit 400 are fixed at two different positions in the direction of the thick arrow in FIG. 1 by the slide unit 200, but the present invention is not limited to this. The camera unit 300 and the lighting unit 400 may be fixed at two different positions in a plane that intersects with the vehicle's traveling direction and faces the wall of the tunnel.

Here, we will provide some additional information regarding the "direction facing the tunnel wall." As mentioned above, a tunnel has a semicircular cross section perpendicular to the vehicle's travel direction. Therefore, the tunnel walls face horizontally near the ground, and face vertically downward near the ceiling. The "direction facing the tunnel wall" refers to the direction facing a wall whose orientation varies depending on the location. The "direction facing the tunnel wall" near the ground is approximately horizontal, for example. On the other hand, the "direction facing the tunnel wall" near the ceiling is approximately vertically upward.

Next, the configuration and function of the guide shaft 240 according to the embodiment will be described in detail.

The camera unit 300 and the lighting unit 400 are separate components that slide independently. Therefore, if the guide shaft 240 is not used, there is a possibility that they will pitch, yaw, roll, or make other irregular movements independently when sliding.

When the imaging system 100 is attached to or detached from the vehicle, the relative positions or attitudes (hereinafter referred to as position/attitude) of the camera unit 300 and the lighting unit 400 may change. Furthermore, their respective positions/attitudes may change due to vibrations while driving, or due to deformation of components such as the frames 261 and 262 and the base plates 310 and 410 caused by the effects of temperature, etc., which may cause their respective positions/attitudes to change.

Such fluctuations may result in the illumination light not properly reaching the area photographed by the camera unit 300, resulting in a problem of insufficient brightness making it impossible to photograph.

As an example, FIG. 7 is a diagram illustrating a state in which the relative positions/orientations of the camera unit 300 and the lighting unit 400 change, causing the illumination light to no longer properly illuminate the area captured by the camera unit 300. FIG. 7(a) is a diagram illustrating a case in which there is no change in the relative positions/orientations of the camera unit 300 and the lighting unit 400, and FIG. 7(b) is a diagram illustrating a case in which there is a change in the relative positions/orientations of the camera unit 300 and the lighting unit 400.

Figure 7 (a) is a view from above of vehicle 500 traveling in the direction of the thick arrow in the figure. 600 is the wall of the tunnel. Shooting range 361 represents the shooting range by camera unit 300, and the intersection of the wall of tunnel 600 and shooting range 361 corresponds to the shooting area of the wall by camera unit 300. Illumination range 461 represents the lighting range by lighting unit 400, and the intersection of the wall of tunnel 600 and lighting range 461 corresponds to the lighting area of the wall by lighting unit 400.

In FIG. 7(a), since there is no change in the relative positions/orientations of the camera unit 300 and the lighting unit 400, the area photographed by the camera unit 300 and the area illuminated by the lighting unit 400 overlap. In other words, the illumination light appropriately illuminates the photographed area.

In contrast, in FIG. 7(b), the postures of the camera unit 300 and the lighting unit 400 change independently, causing the shooting range 362 and the lighting range 462 to change from the state shown in FIG. 7(a), and the shooting area and the lighting area on the wall of the tunnel 600 no longer overlap. In other words, the illumination light does not properly illuminate the shooting area due to the change in the relative position/posture of the camera unit 300 and the lighting unit 400.

In particular, in the embodiment, a line CCD is used as the imaging element, narrowing the shooting range (area) in the traveling direction of the vehicle 500. In this case, since it is sufficient to concentrate the illumination light in a narrow area, there is an effect of good lighting efficiency, and it is more preferable because a sufficient amount of illumination light is required inside a dark tunnel. However, on the other hand, since the shooting area in the traveling direction of the vehicle 500 is narrow, if the relative position/attitude of the camera unit 300 and the illumination unit 400 changes, it is easy for a problem to occur in which the illumination light does not properly hit the shooting area of the camera unit 300.

In order to prevent the problem of the illumination light not properly illuminating the shooting area, the shooting system 100 of the embodiment is provided with a guide shaft 240. A specific description will be given below with reference to FIG. 8. FIG. 8 is a diagram illustrating an example of the configuration of the guide shaft and the guide shaft holding member according to the embodiment.

In FIG. 8, the guide shaft 240 is held by guide shaft holding members 251 and 252. The shaft connecting parts 341 and 342 are fixed to the base plate 310 of the camera unit 300.

The shaft connectors 341 and 342 also have through holes 341-1 and 342-1, respectively. The guide shaft 240 and the camera unit 300 are connected by passing the guide shaft 240 through the through holes 341-1 and 342-1. Similarly, the guide shaft 240 and the lighting unit 400 are connected by passing the guide shaft 240 through the through holes provided in the shaft connectors 441 and 442, respectively.

The camera unit 300 and the lighting unit 400 slide while connected to the guide shaft 240. In other words, they can slide using a common member as a guide.

Therefore, when the position/posture of either the camera unit 300 or the lighting unit 400 changes, the other also changes accordingly. In other words, it is possible to slide or stop the camera unit 300 and the lighting unit 400 while maintaining the relative position/posture relationship between the two. This makes it possible to suppress fluctuations in the relative position/posture between the camera unit 300 and the lighting unit 400, and suppress problems such as the illumination light not properly illuminating the shooting area.

Next, FIG. 9 is a diagram illustrating an example of the shooting area of the camera unit 300 when the camera unit 300 is tilted relative to the tunnel wall, and an example of the lighting area of the lighting unit 400 when the lighting unit 400 is tilted relative to the tunnel wall.

In FIG. 9, the lighting unit 400 irradiates the wall surface of the tunnel 600 with illumination light 466, which is divergent light having an optical axis 465 as its optical axis. The light distribution angle (divergence angle) α of the illumination light 466 is, for example, 1.65 degrees. The camera unit 300 captures the wall surface of the tunnel 600. The optical axis 365 is the optical axis of the camera unit 300.

When the positions of the camera unit 300 and the lighting unit 400 fluctuate due to the vehicle 500 zigzagging, for example, the camera unit 300 and the lighting unit 400 may each tilt relative to the tunnel wall, as shown in FIG. 9. Even in this case, the relative position/posture relationship between the camera unit 300 and the lighting unit 400 is maintained, so that the area photographed by the camera unit 300 and the area illuminated by the lighting unit 400 can be maintained in an overlapping state, as shown in the figure.

In this way, even if the positions of the camera unit 300 and the lighting unit 400 change due to the vehicle 500 meandering, the lighting unit 400 can properly illuminate the shooting area of the camera unit 300. Note that, although the present embodiment has been described in particular as using a line CCD, the same effect can be obtained even when an area CCD or the like is used.

Next, the details of the configuration and operation of the index plungers 350 and 450 according to the embodiment will be described with reference to FIG. 10. FIG. 10 is a diagram illustrating an example of the configuration of the index plungers 350 and 450.

In FIG. 10, the index plunger 350 is fixed to a flat portion of the base plate 310 of the camera unit 300, and the index plunger 450 is fixed to a flat portion of the base plate 410 of the lighting unit 400.

As described above, the camera unit 300 slides on the rail 210, and the lighting unit 400 slides on the rail 220. Since the index plungers 350 and 450 have the same configuration and function, the index plunger 450 will be described here as an example.

The index plunger 450 has a plunger 451 and a plunger holding portion 452. The plunger 451 has a round bar-shaped pin that protrudes toward the ground, a spring that applies a force to the pin toward the ground, and a spring holding portion that holds the pin and the spring. The plunger holding portion 452 holds the plunger 451.

On the other hand, the base 230 of the slide unit 200 is provided with a fitting hole 231 for fitting with the pin at the position where the lighting unit 400 is to be fixed in the sliding direction of the lighting unit 400. Therefore, when the lighting unit 400 slides, in a position where there is no fitting hole 231, the pin hits the base 230 and does not act to fix the lighting unit 400.

When the lighting unit 400 slides and reaches a position where the fitting hole 231 is located, the pin protrudes towards the fitting hole 231 due to the biasing force of the spring, and fits into the fitting hole 231. This prevents the lighting unit 400 from sliding, and the lighting unit 400 is fixed. When it is desired to release the fixation and slide the lighting unit 400 again, the fixation release mechanism is manually operated to release the fixation.

In the embodiment, the base 230 has fitting holes at positions corresponding to positions A and B in the sliding direction. This allows the lighting unit 400 to be fixed at two different positions in a plane that intersects with the vehicle's traveling direction. Similarly, the camera unit 300 can be fixed by the index plunger 350 at two different positions in a plane that intersects with the vehicle's traveling direction.

In the embodiment, a pin is fitted into the fitting hole 231 provided in the base 230 to fix the lighting unit 400, etc., but this is not limited to the above. The lighting unit may be fixed by fitting a pin into a fitting hole provided in the frame 262, the rail 220, etc., or the lighting unit may be positioned by butting it against the base and then fixed by clamping it with a bolt, etc.

Next, an example of the effect of tilting the illumination direction of the illumination light from the lighting unit 400 relative to the shooting direction (image acquisition direction) of the camera unit 300 in an embodiment will be described with reference to FIG. 11.

Like FIG. 7, FIG. 11 is a view from above of a vehicle 500 traveling in the direction of the thick arrow. The shooting direction 363 is the shooting direction of the camera unit 300, and is synonymous with the optical axis direction of the lens of the camera unit. The shooting range 364 represents the range photographed by the camera unit 300. The intersection of the wall surface of the tunnel 600 and the shooting range 364 corresponds to the area of the wall surface photographed by the camera unit 300.

The lighting direction 463 is the lighting direction of the lighting unit 400, and is synonymous with the optical axis direction of the lens of the lighting unit. The lighting range 464 represents the range illuminated by the lighting unit 400. The intersection of the wall surface of the tunnel 600 and the lighting range 464 corresponds to the lighting area of the wall surface by the lighting unit 400.

As described above, if the position/attitude of the camera unit 300 and the lighting unit 400 changes due to vibrations while the vehicle 500 is traveling, the illumination light will not properly hit the area captured by the camera unit 300, resulting in a problem of insufficient brightness making it impossible to capture an image.

Therefore, in the embodiment, the lighting direction of the lighting unit 400 is tilted with respect to the shooting direction of the camera unit 300 toward the shooting area of the wall surface of the tunnel 600. The example in Figure 11 shows the state where the lighting is tilted at an angle θ.

By tilting the lighting in this way and setting the shooting area closer to the center of the lighting area in the direction of vehicle travel, it is possible to prevent the lighting light from not reaching the shooting area.

Here, Figures 12 and 13 are diagrams illustrating an example of the relationship between the tilt angle θ of the optical axis 365 of the camera unit 300 and the optical axis 465 of the lighting unit 400, the light distribution angle α of the illumination light, the distance L from the camera unit 300 to the wall surface of the tunnel 600, and the illumination area S.

Figure 12(a) is a diagram illustrating an example of the relationship between the camera unit 300, the lighting unit 400, and the wall surface of the tunnel 600. In Figure 12(a), the optical axis 365 of the camera unit 300 is perpendicular to the wall surface of the tunnel 600, and the optical axis 465 of the illumination light 466 from the lighting unit 400 is inclined at an inclination angle θ with respect to the optical axis 365 of the camera unit 300. Note that this "perpendicular" does not mean strictly 90 degrees, and there may be some deviation from 90 degrees depending on the inclination of the wall surface of the tunnel 600 and the meandering of the vehicle 500. This point is the same below.

The illumination light 466 illuminates the wall of the tunnel 600 with a light distribution angle α. The distance L from the camera unit 300 to the wall of the tunnel 600 varies from Lmin to Lmax due to the meandering of the vehicle 500, etc. The illumination area S is the area of the tunnel 600 illuminated by the illumination light 466. The illumination light is light that illuminates a circular area, and the illumination area S indicates the diameter of this circular area. However, the illumination light is not limited to light that illuminates a circular area, and may be light that illuminates a rectangular area or light that illuminates an elliptical area.

On the other hand, FIG. 12(b) shows a case where the vehicle 500 is farthest away from the wall of the tunnel 600, with the area photographed by the camera unit 300 and the area illuminated by the lighting unit 400 overlapping.

As an example, if the tilt angle θ is 2.5 degrees and the light distribution angle α is 1.65 degrees, the illumination area S is 330 mm. In this case, when the distance from the camera unit 300 to the wall of the tunnel 600 is 5200 mm, the optical axis 365 of the camera unit 300 is located at the extreme end of the illumination area S (the rightmost end in FIG. 12(b)) on the wall of the tunnel 600. Therefore, the distance of 5200 mm from the camera unit 300 to the wall of the tunnel 600 is an example of the maximum distance Lmax at which the area captured by the camera unit 300 and the area illuminated by the illumination unit 400 can be maintained in an overlapping state.

Figure 13 (c) shows the case where the vehicle 500 is closest to the wall of the tunnel 600 when the area photographed by the camera unit 300 and the area illuminated by the lighting unit 400 overlap.

As an example, if the angle θ is 2.5 degrees and the light distribution angle α is 1.65 degrees, as above, the illumination area S is 330 mm. In this case, when the distance from the camera unit 300 to the wall of the tunnel 600 is 2600 mm, the optical axis 365 of the camera unit 300 is located at the very end of the illumination area S (the leftmost end in FIG. 13(c)) on the wall of the tunnel 600. Therefore, the distance of 2600 mm from the camera unit 300 to the wall of the tunnel 600 is an example of the minimum distance Lmin at which the area captured by the camera unit 300 and the area illuminated by the illumination unit 400 can be maintained in an overlapping state.

In the above, an example was shown in which the lighting unit 400 illuminates the wall surface of the tunnel 600 with divergent light having a light distribution angle α, but the illumination is not limited to divergent light and may be parallel light.

When divergent light is used, the illumination area on the wall of the tunnel 600 can be changed depending on the distance from the lighting unit 400 to the wall of the tunnel 600. The longer the distance L from the lighting unit 400 to the wall of the tunnel 600, the wider the area that can be illuminated.

On the other hand, when illuminating with parallel light, a certain area on the wall of the tunnel 600 can be illuminated regardless of the distance L from the lighting unit 400 to the wall of the tunnel 600.

In the above, the direction of the optical axis 365 of the camera unit 300 is perpendicular to the wall surface of the tunnel 600, and the optical axis 465 of the lighting unit 400 is tilted relative to the optical axis 365 of the camera unit 300, but this is not limited to the above. As shown in FIG. 13(d), the direction of the optical axis 465 of the lighting unit 400 may be perpendicular to the wall surface of the tunnel 600, and the optical axis 365 of the camera unit 300 may be tilted relative to the optical axis 465 of the lighting unit 400. FIG. 13(d) shows an example in which the optical axis 365 of the camera unit 300 is tilted by an inclination angle θ relative to the optical axis 465 of the lighting unit 400. In other words, the optical axis 465 of the lighting unit 400 and the optical axis 365 of the camera unit 300 may be tilted relatively at the inclination angle θ.

By tilting the optical axis 465 of the lighting unit 400 and the optical axis 365 of the camera unit 300 relative to each other in this way, light can be directed toward the shooting area of the camera unit 300. Even if the horizontal shooting area (horizontal shooting field of view) on the wall surface of the tunnel 600 is narrow, the shooting area by the camera unit 300 can be appropriately illuminated with light from the lighting unit 400.

In addition, by combining a configuration that uses the guide shaft 240 to maintain the relative position/posture relationship between the camera unit 300 and the lighting unit 400 with a configuration that illuminates with a tilted lighting direction, the effect becomes more pronounced. In other words, even when a line CCD is used as the imaging element and shooting is performed under conditions of good lighting efficiency, the problem of the illumination light from the lighting unit 400 not properly illuminating the shooting area by the camera unit 300 can be more significantly suppressed.

In addition, even if the distance between the tunnel and the wall changes due to the vehicle meandering or the tunnel size is different, the problem of the illumination light from the lighting unit 400 not properly illuminating the area captured by the camera unit 300 can be suppressed.

Figure 14 is a diagram illustrating an example of the relationship between the meandering of the vehicle 500, the shooting area of the camera unit 300, and the lighting area of the lighting unit 400. The vehicle 500 is traveling while meandering in the direction indicated by the arrow in Figure 14.

As shown on the right side of Figure 14, when the maximum distance Lmax from the camera unit 300 to the wall of the tunnel 600 is 5200 mm, the optical axis 365 of the camera unit 300 is located at the very end (the leftmost end in Figure 14) of the illumination area S on the wall of the tunnel 600. In other words, this is one of the limits at which the overlapping state between the area photographed by the camera unit 300 and the area illuminated by the illumination unit 400 can be maintained.

On the other hand, as shown on the left side of Figure 14, when the minimum distance Lmin from the camera unit 300 to the wall of the tunnel 600 is 2600 mm, the optical axis 365 of the camera unit 300 is located at the very end (the rightmost end in Figure 14) of the illumination area S on the wall of the tunnel 600. In other words, this is the other limit at which the overlapping state between the area photographed by the camera unit 300 and the area illuminated by the illumination unit 400 can be maintained.

When the angle θ is 2.5 degrees and the light distribution angle α is 1.65 degrees (see Figure 12), it can be seen that the vehicle 500 is allowed to meander when the distance L from the camera unit 300 to the wall of the tunnel 600 is in the range of 2600 mm to 5200 mm.

<Operation of the imaging system>
Next, the operation of the imaging system 100 according to the embodiment will be described with reference to Fig. 15. Fig. 15 is a flowchart showing an example of the operation of the imaging system 100.

First, in step S141, the imaging system 100 is attached to the vehicle 500.

Next, in step 142, the slide unit 200 fixes the camera unit 300 and the lighting unit 400 to position A. In this case, the user manually slides the camera unit 300 and the lighting unit 400 and fixes them to position A.

Next, in step S143, while the vehicle 500 is traveling from the entrance to the exit of the tunnel 600, an image of the area 600A of the wall of the tunnel 600 on the side where the sidewalk 730 does not exist is captured. In this case, image capture is started when the vehicle 500 enters the entrance of the tunnel 600. The instruction to start image capture is given by the user.

When the vehicle 500 reaches the exit of the tunnel 600, the image capture stops. The user issues an instruction to stop the image capture. Up to this point, image data of half of the walls of the tunnel 600 are stored in the HDD 114.

Next, in step S144, the slide unit 200 fixes the camera unit 300 and the lighting unit 400 to position B. In this case, the user manually slides the camera unit 300 and the lighting unit 400 and fixes them to position B.

Next, in step S145, while the vehicle 500 is driven from the entrance to the exit of the tunnel 600 in the direction opposite to the driving direction in step S1103, an image of the area 600B of the wall of the tunnel 600 on the side where the sidewalk 730 is located is captured. As described above, the user issues an instruction to start/stop capturing images. As a result, the remaining half of the entire wall of the tunnel 600 is captured and stored in the HDD 114.

Next, in step S146, the user checks whether there are any problems with the captured image, and if there are no problems (step S146, No), the capture ends. On the other hand, if there are any problems (step S146, Yes), the process returns to step S1102 and captures the image again.

As a result, it is possible to photograph objects such as tunnel walls without the trouble of adjusting the camera focus or measuring the cross-sectional shape of the object.

In the embodiment, the camera unit 300 and the lighting unit 400 are fixed at positions A and B to the slide unit 200, but such fixing may also be performed to the vehicle 500. The configuration is described below.

Attach the camera unit 300 and the lighting unit 400 to a vehicle fixing base plate. In the case of position A, the camera unit 300 and the lighting unit 400 are fixed by fixing the vehicle fixing base plate to the right end of the roof of the vehicle facing the direction of travel using a hook part.

In the case of position B, the camera unit 300 and the lighting unit 400 are fixed by fixing the vehicle fixing base plate to the left end of the roof of the vehicle facing the direction of travel using a hook part.

In addition, parts similar to the guide shaft 240 and the guide shaft holding members 251 and 252 are provided on the vehicle fixing base plate, and the shaft connecting parts 341 and 342, as well as 441 and 442, are connected to the guide shaft 240. This makes it possible to suppress the effects of fluctuations in the position/attitude of the camera unit 300 and the lighting unit 400.

In this example, the imaging system 100 does not need to have the slide unit 200. Also, the camera unit 300 and the lighting unit 400 do not need to have the index plungers 350 and 450, respectively.

As a result, even when fixed to the vehicle 500, the same effect can be obtained as when the camera unit 300 and the lighting unit 400 are fixed to positions A and B relative to the slide unit 200.

[First embodiment]
Next, a description will be given of an image capturing system 100a including an image capturing device according to the first embodiment. Note that the same components as those in the above-described embodiment are given the same part numbers, and duplicated descriptions will be omitted as appropriate.

<Configuration example of imaging system 100a>
First, the configuration of the imaging system 100a will be described with reference to Fig. 16 and Fig. 17. Fig. 16 is a perspective view illustrating an example of the configuration of the imaging system 100a according to the first embodiment, and Fig. 17 is a perspective view showing the imaging system 100a in a state where the exterior cover is closed.

As shown in Figs. 16 and 17, the photography system 100a has a mount 270, an exterior cover 280, a camera unit 300, and a lighting unit 400. Of these, the mount 270, the exterior cover 280, and the camera unit 300 constitute the photography device 180. The lighting unit 400 is an example of a lighting device.

The mount 270 is a member on which the exterior cover 280, the camera unit 300, and the lighting unit 400 are mounted. In the case of a vehicle, which is an example of a moving body, the exterior cover 280, the camera unit 300, and the lighting unit 400 can be fixed to the roof of the vehicle via the mount 270.

The stand 270 has an exterior cover 280 placed thereon so as to be openable and closable along the opening/closing direction 271. The exterior cover 280 is an example of an exterior member that can cover at least a portion of the image capture device 180 and is provided so as to be openable and closable. The exterior cover 280 can provide dust and water protection by covering the camera unit 300 and the lighting unit 400, for example. The exterior cover 280 can be made of a material such as metal or resin. Figure 16 shows the exterior cover 280 in an open state, and Figure 17 shows the exterior cover 280 in a covered state.

When the exterior cover 280 is opened, the camera unit 300 including the camera 331 and the lighting unit 400 including the lighting light source unit 431 are exposed to the outside and are ready to take pictures. On the other hand, when the exterior cover 280 is closed, the camera unit 300 and the lighting unit 400 are closed and cannot take pictures. When the image taking device 180 is not taking pictures, the exterior cover 280 is closed. The exterior cover 280 can be opened and closed by the photographer of the image taking system 100a, for example, but it may also be opened and closed electrically using a motor or the like as a driving source.

The exterior cover 280 also has a lighting reflecting member fixed to the inside of the exterior cover 280 so that the lighting reflecting member can move in conjunction with the opening and closing operation of the exterior cover 280. Note that in Figures 16 and 17, the lighting reflecting member is hidden by the exterior cover 280 and is not shown.

<Configuration example of illumination reflecting member>
Next, the configuration of the illumination reflecting member will be described with reference to Fig. 18 and Fig. 19. Fig. 18 is a perspective view for explaining an example of the configuration of the illumination reflecting member, and Fig. 19 is a cross-sectional view. Each is an enlarged view showing the configuration around the illumination reflecting member.

The illumination light source unit 431 includes an illumination lens 431a and is a unit that illuminates the shooting area of the camera 331 on the tunnel wall. The illumination light source unit 431 emits illumination light along an illumination direction 381 indicated by a dashed arrow. Note that the illumination light from the illumination light source unit 431 is divergent or converging light, and the illumination direction 381 indicates the direction along which the central axis of the illumination light runs.

The illumination lens 431a is a lens assembly made up of multiple lens elements fixed to the lens barrel, and can focus illumination light on the shooting area of the camera 331. Note that a lens element refers to a single lens that makes up the lens assembly. The front illumination lens 431b is the lens element that is closest to the tunnel wall surface among the multiple lens elements that make up the illumination lens 431a.

The camera 331 includes a photographing lens 331a and an image sensor 331c, and is a unit that photographs the tunnel wall surface. The photographing lens 331a is a lens assembly made up of multiple lens elements fixed to a lens barrel, and can collect the light reflected by the tunnel wall surface, forming an image of the tunnel wall surface on the imaging surface of the image sensor 331c.

The imaging element 331c is an example of an imaging means for capturing an image of the tunnel wall surface through the photographing lens 331a. The imaging element 331c is an imaging element such as a CCD, and can output an image of the tunnel wall surface captured by the photographing lens 331a. The front lens 331b is the lens element that is closest to the tunnel wall surface among the multiple lens elements that make up the photographing lens 331a.

The illumination reflecting member 371 is an example of an illumination deflecting member that deflects at least a portion of the illumination light capable of illuminating the photographing area by the photographing device 180 toward the photographing lens 331a. The illumination reflecting member 371 is, for example, a flat mirror having a reflective surface. However, the illumination deflecting member is not limited to the illumination reflecting member 371. Instead of a flat mirror, the illumination deflecting member may include, for example, a spherical mirror or an aspherical mirror, or a diffractive element having a diffractive structure, as long as it deflects at least a portion of the illumination light toward the photographing lens. It may also include a diffusing surface that diffuses and reflects the illumination light, or a scattering surface that scatters the illumination light.

The illumination reflecting member 371 reflects the illumination light from the illumination light source unit 431 along a reflection direction 382 indicated by a dashed arrow. Note that the reflected light from the illumination reflecting member 371 is also light that diverges or converges, similar to the illumination light from the illumination light source unit 431, and the reflection direction 382 indicates the direction along which the central axis of the reflected light runs.

The lighting reflector 371 is fixed to the inside of the exterior cover 280 (see FIG. 16) and can move along the opening/closing direction 271 that intersects with the lighting direction 381 as the exterior cover 280 is opened or closed.

When the exterior cover 280 is covered, for example when the image capturing device 180 is not capturing images, the exterior cover 280 positions the illumination reflecting member 371 at a light-shielding position 383 where at least a portion of the illumination reflecting member 371 blocks at least a portion of the illumination light, as shown in FIG. 18. Note that the light-shielding position 383 refers to an axis that intersects with the opening/closing direction 271, and the exterior cover 280 can position the illumination reflecting member 371 on this axis.

In this state, the illumination reflecting member 371 reflects the illumination light and irradiates at least a portion of the illumination light onto the photographing lens 331a. The illumination reflecting member 371 can heat the photographing lens 331a with the irradiated light. In other words, the illumination reflecting member 371 functions as a heating means that heats the photographing lens 331a with energy based on the illumination light. This heating can prevent condensation on the photographing lens 331a.

When heating the photographing lens 331a to prevent condensation on the photographing lens 331a, the entire photographing system 100a does not need to operate, and at least the illumination light source unit 431 needs to be in an operable state. Therefore, when heating, it is preferable to supply power only to the illumination light source unit 431 and not to components other than the illumination light source unit 431, since this reduces power consumption.

Here, it is more preferable that the illumination reflecting member 371 irradiates light onto the front lens 331b. The front lens 331b has an interface with the outside, and is therefore the part of the photographing lens 331a that is most susceptible to condensation. By irradiating light onto this front lens 331b, the front lens 331b is directly heated, and condensation on the front lens 331b can be suitably prevented. In addition, since the front lens 331b transmits a portion of the irradiated light, the transmitted light of the light irradiated onto the front lens 331b can be made to reach lens elements other than the front lens 331b that constitute the photographing lens 331a. Therefore, lens elements other than the front lens 331b are also heated in parallel, and condensation on these lens elements can also be prevented.

However, the area of the photographing lens 331a onto which the illumination reflecting member 371 irradiates light is not limited to the photographing front lens 331b, and may be the lens barrel of the photographing lens 331a. Furthermore, the photographing device 180 may position the illumination reflecting member 371 so that at least a portion of the illumination light is irradiated not only onto the photographing lens 331a, but also onto the illumination lens 431a. When irradiating the illumination lens 431a with light, irradiating the illumination front lens 431b with light can provide the same effect as when irradiating the photographing front lens 331b with light.

On the other hand, when the exterior cover 280 is opened, for example when photographing with the photographing device 180, the exterior cover 280 places the illumination reflecting member 371 in a non-light-shielding position 384 where the illumination reflecting member 371 does not block the illumination light. The non-light-shielding position 384 refers to an axis that intersects with the opening/closing direction 271, and the exterior cover 280 can place the illumination reflecting member 371 on this axis.

In this case, the illumination reflecting member 371 is positioned away from the optical path of the illumination light from the illumination light source unit 431, so that it does not impede image capture by the image capture device 180.

Here, FIG. 20 is a diagram showing an example of the arrangement of each component within the exterior cover 280. Note that FIG. 20 shows the exterior cover 280 in a closed state.

As shown in FIG. 20, in addition to the illumination light source unit 431, camera 331, and illumination reflecting member 371 described in FIG. 18 and FIG. 19, the illumination light source unit 432, camera 332, illumination reflecting member 372, illumination light source unit 433, camera 333, and illumination reflecting member 373 are arranged on the inside of the exterior cover 280. Like the illumination reflecting member 371, the illumination reflecting members 372 and 373 are also fixed to the inside of the exterior cover 280 and can move between a light-shielding position and a light-non-shielding position in conjunction with the opening and closing operation of the exterior cover 280.

The illumination reflecting member 372 is adapted to irradiate and heat at least a portion of the illumination light from the illumination light source unit 432 onto at least the photographing lens of the camera 332, thereby preventing condensation on the photographing lens. The illumination reflecting member 373 is adapted to irradiate and heat at least a portion of the illumination light from the illumination light source unit 433 onto at least the photographing lens of the camera 333, thereby preventing condensation on the photographing lens. In this case as well, the same effect as that described for the illumination reflecting member 371 can be obtained.

<Functions and Effects of the Photographing Device 180 and the Photographing System 100a>
Next, the effects of the photographing device 180 and the photographing system 100a will be described.
Conventionally, in imaging devices, condensation may occur on the parts of the imaging device that are exposed to the outside air, such as the imaging lens or lighting lens. In particular, when imaging the wall surface of a tunnel as an object, condensation is likely to occur when entering the tunnel from the outside because the humidity inside the tunnel tends to be very high. When condensation occurs on the lens surface of the imaging lens or lighting lens, the moisture on the lens surface acts on the imaging light or lighting light, degrading the quality of the captured image and making it impossible to perform image analysis appropriately.

In addition, in order to prevent condensation on the photographic lens included in the photographing device, a configuration has been disclosed in which a lens holder made of a material with high thermal conductivity, such as aluminum, is abutted against a substrate on which an imaging element, such as a CCD, is mounted, thereby transferring heat generated by the imaging means to heat the photographic lens.

However, with this configuration, since heat generated by the image sensor is transferred, sufficient heat may not be obtained if the image sensor is not in operation, or the heat may diffuse as it is transferred through the lens holder, resulting in insufficient heating efficiency. The larger the lens, the more pronounced the diffusion of heat in the lens holder, and the lower the heating efficiency.

In this embodiment, the imaging device has a heating means for heating the imaging lens with energy based on illumination light capable of illuminating the imaging range of the imaging device. For example, the heating means includes an illumination reflecting member (illumination deflecting member) that deflects at least a portion of the illumination light toward the imaging lens, and heats the imaging lens with the energy of light irradiated onto the imaging lens using the illumination reflecting member. By heating the imaging lens with the energy of the illumination light, the imaging lens can be heated without going through a heat transfer member, eliminating the effects of thermal diffusion of the heat transfer member and allowing the imaging lens to be heated efficiently.

In this embodiment, the photographic lens includes multiple photographic lens elements, and the heating means heats the front lens, which is the part of the photographic lens that is most susceptible to condensation, from the multiple photographic lens elements. This directly heats the front lens, which is the part of the photographic lens that is most susceptible to condensation, and more effectively prevents condensation on the front lens.

In addition, because the front lens transmits a portion of the irradiated light, the transmitted light can reach the lens elements other than the front lens that make up the photographic lens and heat them in parallel, which also effectively prevents condensation on these lens elements.

In addition, in this embodiment, the imaging system is provided with an illumination reflecting member that is movable between a light-shielding position in which at least a portion of the illumination deflecting member blocks at least a portion of the illumination light capable of illuminating the imaging range of the imaging system, and a non-light-shielding position in which the illumination reflecting member does not block the illumination light. This allows the illumination reflecting member to be placed in the non-light-shielding position when imaging is performed using the imaging system, and prevents the illumination reflecting member from blocking the illumination light and impeding imaging. In addition, it is possible to easily switch between a state in which the imaging lens is heated to prevent condensation and a state in which imaging is performed.

In addition, in this embodiment, the illumination reflecting member is attached to an exterior cover (exterior member) that can shield the imaging device and is openable and closable, and moves between a light-shielding position and a light-non-shielding position in conjunction with the opening and closing of the exterior cover. In the imaging system, when imaging is not being performed, the imaging unit and illumination unit, etc. are shielded by the exterior cover to provide dust and water protection, and when imaging is being performed, the exterior cover is opened. With this configuration, it is possible to easily switch between a state in which the imaging lens is heated to prevent condensation and a state in which imaging is performed, without adding a dedicated configuration for switching.

However, the lighting reflector does not necessarily need to be linked to the opening and closing of the exterior cover, and can be configured to be movable between the light-shielding position and the light-non-shielding position independently of the exterior cover.

In this embodiment, the lighting device has an illumination lens including a plurality of illumination lens elements, and the photographing lens includes a plurality of photographing lens elements. The heating means can heat both the photographing front lens that is provided closest to the tunnel wall (subject) among the plurality of photographing lens elements, and the illumination front lens that is provided closest to the tunnel wall subject among the plurality of illumination lens elements. This configuration makes it possible to prevent condensation on both the photographing lens and the illumination lens.

[Other Preferred Embodiments]
In the first embodiment described above, a configuration has been given in which the heating means includes an illumination deflection member, and the imaging lens is heated by the energy of light irradiated by the illumination deflection member, but the configuration of the heating means is not limited to this.

For example, the heating means may include a conversion member that receives at least a portion of the illumination light capable of illuminating the photographing area of the photographing device and converts the energy of the absorbed light into thermal energy. The conversion member heats the photographing lens by contacting a portion of the conversion member with the photographing lens and transmitting thermal energy. The conversion member may be, for example, a material that is colored in a color that has a high absorption rate of the illumination light.

Even with this configuration, the thermal energy generated by the conversion member can be used to heat the photographing lens without using a heat transfer member, and the same effects as those described in the first embodiment can be obtained.

Although the above describes examples of embodiments of the present invention, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims.

Specifically, the vehicle equipped with the camera may be a two-wheeled vehicle, a four-wheeled vehicle such as a general-purpose car, a construction/agricultural/industrial vehicle, a railway vehicle, a special vehicle, or an air vehicle such as a drone. These are collectively referred to as a mobile object.

In the embodiment, a tunnel has been described as an example of an object, but the object is not limited to this and may also include pipes used to transport gas, liquid, powder, or granular materials. The object may also include an elevator shaft, such as a vertical hole-shaped reinforced concrete structure through which an elevator runs.

Note that all ordinal numbers, quantities, and other numbers used in the description of the embodiments are provided as examples to specifically explain the technology of the present invention, and the present invention is not limited to the exemplified numbers. In addition, the connections between the components are provided as examples to specifically explain the technology of the present invention, and the connections that realize the functions of the present invention are not limited to these.

The division of blocks in the functional block diagram is just one example, and multiple blocks may be realized as one block, one block may be divided into multiple blocks, and/or some functions may be transferred to other blocks. Furthermore, the functions of multiple blocks having similar functions may be processed in parallel or in a time-shared manner by a single piece of hardware or software.

The embodiment also includes a photographing method. For example, the photographing method is a photographing method using a photographing device that has a photographing lens and photographs an object, and includes a step of photographing an image of the object using the photographing lens and a step of heating the photographing lens with energy based on illumination light that can illuminate an area photographed by the photographing device. With such a photographing method, it is possible to obtain the same effect as the photographing device described above.

100: Imaging system 180: Imaging device 270: Stand 271: Opening/closing direction 280: Exterior cover (an example of an exterior member)
300 Camera unit 331 to 334 Camera 331a Shooting lens 331b Shooting front lens 331c Shooting element (one example of imaging means)
331-1, 334-1 Lens 371 Illumination reflecting member (an example of an illumination deflecting member)
381: Illumination direction; 382: Reflection direction; 383: Light blocking position; 384: Non-light blocking position; 400: Illumination unit (an example of an illumination device)
431 to 436 Illumination light source unit 431a Illumination lens 431b Illumination front lens 500 Vehicle (an example of a moving body)
600 Tunnel (an example of a structure)
601 to 603 Wall surface (an example of the target object)

Patent No. 5005186

Claims (8)

An imaging device for photographing an object,
The photographic lens,
an imaging means for capturing an image of the object through the photographing lens;
an illumination means for illuminating an area photographed by the photographing device with illumination light;
a heating unit for heating the photographing lens by energy based on the illumination light,
The heating means includes an illumination deflection member that deflects at least a portion of the illumination light toward the photographing lens, and the photographing lens is heated by the energy of the light irradiated onto the photographing lens using the illumination deflection member. the taking lens includes a plurality of taking lens elements;
2. The photographing apparatus according to claim 1, wherein the heating means heats a front lens element, which is disposed closest to the object, among the plurality of photographing lens elements. The illumination deflection member is provided to be movable between a light-shielding position where at least a part of the illumination deflection member blocks at least a part of the illumination light and a non-light-shielding position where the illumination deflection member does not block the illumination light , and by disposing the illumination deflection member at the light-shielding position, at least a part of the illumination deflection member irradiates at least a part of the illumination light to the photographing lens.
3. The imaging device according to claim 1. 4. The photographing device according to claim 3, wherein the illumination deflection member is attached to an exterior member that is capable of shielding at least a portion of the photographing device and is openable and closable, and moves between the light-shielding position and the light-unshielding position in conjunction with the opening and closing operation of the exterior member. A photographing system comprising the photographing device according to any one of claims 1 to 4. the illumination means comprises an illumination lens including a plurality of illumination lens elements;
the taking lens includes a plurality of taking lens elements;
6. The photographing system according to claim 5, wherein the heating means heats both a front photographing lens element that is disposed closest to the object among the plurality of photographing lens elements, and a front illumination lens element that is disposed closest to the object among the plurality of illumination lens elements. A photographing apparatus according to any one of claims 1 to 4 or a photographing system according to claim 5 or 6,
The object is a wall surface of a structure,
A moving body that photographs the wall surface of the structure using the photographing device or the photographing system while moving. A method for photographing an object using a photographing device having a photographing lens, comprising:
capturing an image of the object by the photographing lens ;
illuminating an area photographed by the photographing device with illumination light;
heating the photographing lens with energy based on the illumination light;
In the heating step, the photographing lens is heated by the energy of light irradiated onto the photographing lens using an illumination deflection member that deflects at least a part of the illumination light toward the photographing lens.

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