Imaging system, control method of imaging system, and program

Abstract

To realize photographing under a predetermined relative position between an illumination part for illuminating a subject area and an imaging part for imaging a subject area, even when the relative positions among the illumination part, the imaging part, and the subject area are not identical for each shot.SOLUTION: An imaging system includes: an illumination part for irradiating a terahertz wave; an imaging part for photographing an image of a subject; and a control part for controlling either the illumination part or the imaging part so that a positional relationship between the illumination part irradiating the subject area and the imaging part photographing the subject area satisfies a predetermined condition, in accordance with a positional relationship between a subject area photographed by the imaging part and the imaging part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an imaging system, a control method for an imaging system, and a program. [Background technology]

[0002] In recent years, there has been a demand for technology to detect objects carried by a person, such as detecting dangerous materials carried by the person, in order to prevent crimes committed by the person carrying concealed dangerous materials. One such technology is an active terahertz system that uses terahertz waves. In an active terahertz system, an object is irradiated with terahertz waves and the terahertz waves reflected from the object are detected by a terahertz camera, thereby performing imaging and inspection. For example, Patent Document 1 discloses a method of irradiating an object with terahertz waves, obtaining a terahertz wave image using the reflected waves, and detecting concealed objects from the obtained image. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-181925 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, for example, when photographing is performed in a situation where the lighting unit, the imaging unit, the target area to be photographed, etc. are not fixed, the positional relationship between the lighting unit, the imaging unit, and the target area to be photographed may not be the same each time photographing is performed. In this case, as in the technology of Patent Document 1, if the positional relationship between the lighting unit that irradiates the target area and the imaging unit that photographs the target area does not change regardless of the positional relationship between the target area and the imaging unit, photographing may be performed under a positional relationship between the lighting unit and the imaging unit that is not predetermined. The present invention aims to realize photography under a predetermined positional relationship between an illumination unit that illuminates a target area and an imaging unit that images the target area, even if the positional relationship between the illumination unit, imaging unit, and target area to be photographed is not the same each time photography is performed. [Means for solving the problem]

[0005] In order to solve the above problem, the imaging system of the present invention includes an illumination unit that irradiates terahertz waves, an imaging unit that images a subject, and a control unit that controls the illumination unit or the imaging unit so that the positional relationship between the illumination unit that irradiates the target area imaged by the imaging unit and the imaging unit that images the target area satisfies predetermined conditions, depending on the positional relationship between the illumination unit that irradiates the target area imaged by the imaging unit and the imaging unit. [Effects of the Invention]

[0006] According to the present invention, even if the positional relationship between the lighting unit, the imaging unit, and the target area to be photographed is not the same each time photography is taken, photography can be achieved under a predetermined positional relationship between the lighting unit that illuminates the target area and the imaging unit that photographs the target area. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of a functional configuration of an imaging system. [Figure 2] FIG. 1 is a diagram illustrating a hardware configuration of an imaging system. [Figure 3] 1A and 1B are schematic diagrams illustrating how the imaging system is used. [Figure 4] FIG. 1A is a diagram showing an image obtained by photographing an object with a visible light camera, and FIG. 1B is a diagram showing an image obtained by photographing an object with an imaging system. [Figure 5] 10A and 10B are diagrams showing examples of the arrangement of an illumination unit and an imaging unit in an imaging system. [Figure 6] 10A and 10B are diagrams showing the positional relationship between an illumination unit, an imaging unit, and an object. [Figure 7] FIG. 10 is a diagram showing an illumination unit management table. [Figure 8] 10 is a flowchart showing the flow of a control process. [Figure 9] FIG. 10 is a diagram showing a first modification of the arrangement of the illumination unit and the imaging unit in the imaging system. [Figure 10] 10A to 10D are diagrams showing a second modification of the arrangement of the illumination unit and the imaging unit in the imaging system. [Figure 11] FIG. 10 is a diagram illustrating a configuration of an imaging system according to a second embodiment. [Figure 12] FIG. 10 is a diagram illustrating an illumination unit management table according to the second embodiment. [Figure 13] 10A and 10B are flowcharts showing the flow of control processing in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a diagram showing an example of the functional configuration of an image capturing system 100 according to the first embodiment. The image capturing system 100 of this embodiment is a system that detects an object being held by a subject from an image obtained by capturing the object by detecting reflected light from the subject when the subject is irradiated with terahertz waves. Terahertz waves are electromagnetic waves with a frequency of 30 GHz or more and 30 THz or less. Terahertz waves have different properties from visible light, such as being more rectilinear and transparent than visible light. The imaging system 100 of this embodiment detects an object to be photographed in a non-destructive and non-contact manner by irradiating the object with terahertz waves and photographing the object.

[0009] Hereinafter, the object to be photographed may be simply referred to as the object. The object may also be regarded as the object to be inspected by the imaging system 100. Hereinafter, the area to be photographed by the imaging system 100 may be referred to as the target area. In a situation where the object is located within a range predetermined as the area where photography will be performed, such as when the imaging system 100 is photographing the object, the target area is the area where the object is located. In a situation where the object is not located within the range predetermined as the area where photography will be performed, such as when the imaging system 100 is preparing to photograph the object, the target area is the area predetermined as the area where the object is located at the time of photography. The predetermined range and the predetermined area may be an area corresponding to a location set up for photography, or may be the entire area included in the angle of view of the imaging unit 130, such as the front of the imaging unit 130.

[0010] The imaging system 100 includes an illumination unit 120, an imaging unit 130, a processing unit 140, a display unit 150, an acquisition unit 160, a storage unit 170, a detection unit 180, and a control unit 110. The illumination unit 120 includes a light-emitting device (not shown) that emits terahertz waves. Examples of light-emitting devices include those equipped with an antenna composed of a negative differential resistance element and a resonant circuit. Examples of negative differential resistance elements include resonant tunneling diodes. The light-emitting device may be any existing device that emits terahertz waves. The illumination unit 120 may also include multiple light-emitting devices. When multiple light-emitting devices are included in the illumination unit 120, the light-emitting intensity can be increased by resonantly driving the multiple light-emitting devices, or the light-emitting devices can be arranged in an array to irradiate the entire object with terahertz waves. The imaging system 100 of this embodiment includes multiple illumination units 120. In the illustrated example, the imaging system 100 includes four illumination units 120. However, the number of illumination units 120 included in the imaging system 100 is not limited to the illustrated example.

[0011] The imaging unit 130 captures an image of the object by detecting the intensity of the terahertz waves irradiated from the illumination unit 120 and reflected by the object. The imaging unit 130 has a detection device that detects the terahertz waves. Examples of the detection device include a Schottky barrier diode, a bolometer, and a MEMS resonator. The detection device may be any existing device that detects terahertz waves. The processing unit 140 processes the imaging signal obtained by the imaging unit 130. More specifically, the processing unit 140 converts the imaging signal into an image signal by processes such as demosaicing and black level adjustment. Furthermore, when converting the imaging signal, the processing unit 140 performs image correction such as blemish correction and shading correction. Furthermore, the processing unit 140 may perform image processing such as noise removal and edge extraction, and object recognition by image recognition.

[0012] Display unit 150 displays the image processed by processing unit 140. Display unit 150 may also display the result of image recognition by processing unit 140. In addition, when the result of image recognition by processing unit 140 is displayed on display unit 150, if a predetermined object is image-recognized by processing unit 140, the recognized object may be displayed on display unit 150 in an emphasized manner. The acquisition unit 160 acquires information from an external device of the imaging system 100 . The storage unit 170 stores the information acquired by the acquisition unit 160 and the information input to the imaging system 100. The contents of the information stored in the storage unit 170 will be described in detail later.

[0013] The detection unit 180 detects the positional relationship between the illumination unit 120, the imaging unit 130, and the object. The detection unit 180 may have a distance sensor (not shown) that measures distance, and may use this sensor to measure the distance from the object to the imaging unit 130 or the distance from the object to the illumination unit 120, thereby detecting the positional relationship between the illumination unit 120, the imaging unit 130, and the object. Furthermore, when the illumination unit 120 emits terahertz waves onto the object, the detection unit 180 may determine the position of the object and the distance from the object to the imaging unit 130, etc., based on the intensity of the reflected waves reflected by the object and detected by the imaging unit 130. Furthermore, the detection unit 180 may have a position sensor (not shown) that detects a two-dimensional or three-dimensional area in which the object is located, and may use this position sensor to detect the positional relationship between the illumination unit 120, the imaging unit 130, and the object. Furthermore, the position sensor may be a sensor that optically detects the area in which the object is located, or a sensor that magnetically detects the area in which the object is located. The object to be detected by the detection unit 180 may be predetermined, or may be any object located in an area that can be detected by the detection unit 180. The detection unit 180 also transmits information indicating the detection result to the control unit 110.

[0014] The control unit 110 controls the illumination unit 120, the imaging unit 130, and the detection unit 180. When the control unit 110 acquires the detection result by the detection unit 180, the control unit 110 identifies, from the acquired result, which of the multiple illumination units 120 will cause the reflected wave from the object to be incident on the detection device of the imaging unit 130 when irradiating the object with terahertz waves. The control unit 110 then determines the identified illumination unit 120 as the illumination unit 120 that will irradiate the object with terahertz waves. The control unit 110 controls the switching on and off of the illumination unit 120 and the intensity of light emitted by the terahertz waves when irradiating terahertz waves from the illumination unit 120. Examples of the intensity of light emitted by the terahertz waves include the luminous intensity of the terahertz waves irradiated from the illumination unit 120, the luminous flux of the terahertz waves irradiated from the illumination unit 120, and the illuminance of a location that emits light due to the terahertz waves irradiated from the illumination unit 120. The control unit 110 also controls the exposure time, aperture, focus, etc. of the imaging unit 130. The control unit 110 also controls whether the detection unit 180 is activated or deactivated. The processing by the control unit 110 and the processing unit 140 is realized by a processing device such as a CPU, an ISP, etc. The control unit 110 and the processing unit 140 may be configured by the same processing device, or may be configured by separate processing devices.

[0015] In the imaging system 100, the illumination unit 120 and the imaging unit 130 may be provided as an integrated unit, or may be provided independently as separate devices. When the illumination unit 120 and the imaging unit 130 are provided as an integrated unit, the positional relationship between the illumination unit 120 and the imaging unit 130 may be fixed. When the illumination unit 120 and the imaging unit 130 are provided independently, the positional relationship between the illumination unit 120 and the imaging unit 130 may change by changing the position of one of the illumination unit 120 and the imaging unit 130. In the illustrated example, the imaging system 100 is provided with the processing unit 140 and the display unit 150, but this is not limiting. The processing unit 140 and the display unit 150 may be provided in a device external to the imaging system 100, and the imaging system 100 may transmit information obtained by image capture by the imaging unit 130 to the processing unit 140 and the display unit 150 via a network. In this case, the network connecting the imaging system 100 with the processing unit 140 and the display unit 150 may be a network configured to enable transmission and reception of information. The network may be the Internet, a LAN, a WAN, a cellular network such as LTE or 5G, a wireless network, a dedicated digital line, Bluetooth (registered trademark), Bluetooth Low Energy, or a combination thereof.

[0016] FIG. 2 is a diagram showing the hardware configuration of the imaging system 100. The imaging system 100 includes a CPU 101, a storage device 102, a memory 103, an operation I / F unit 104, and a communication I / F unit 105. The CPU 101 controls the entire imaging system 100. The CPU 101 loads programs from the storage device 102 into the memory 103 and executes them to perform various controls. The storage device 102 stores an operating system (OS), programs, management data, data collected from external systems and devices, etc. The memory 103 functions as a work area for the CPU 101, etc. The operation I / F unit 104 outputs various data and execution results of programs to a connected output device such as a display, and receives input from a connected input device. The communication I / F unit 105 is a network interface for communicating with external systems and devices. The configuration shown in FIG. 2 can also be considered as the hardware configuration of the control unit 110 in the imaging system 100.

[0017] Fig. 3 is a schematic diagram of a usage form of the imaging system 100. Fig. 3 shows an example in which the imaging system 100 captures an image of an object 200, which is a person under inspection, and detects an object that the object 200 is carrying concealed. FIG. 3A shows an example in which the imaging system 100 is provided with a holder 210, and an inspector inspecting the object 200 grasps the holder 210 to use the imaging system 100. The inspector may use the imaging system 100 to prioritize capturing images of portions of the object 200 that are likely to contain dangerous objects, or may capture images of the object 200 so that the entire object 200 fits within the angle of view of the imaging unit 130. Examples of places where such an imaging system 100 is used include airport security stations and places where entry to event venues is managed. Inspectors use the imaging system 100 to detect objects concealed in the object 200, thereby preventing incidents that may be caused by the object 200 carrying dangerous objects. Note that the object 200 may not only be a person, but also any object that can be carried, such as a bag, cardboard box, or envelope.

[0018] 3(B), in the imaging system 100, when at least one of the plurality of illumination units 120 illuminates the object 200, the reflection from the object 200 is detected by the imaging unit 130. Then, an image obtained in accordance with the result of detection by the imaging unit 130 is processed by the processing unit 140 and displayed on the display unit 150. An inspector checks the image displayed on the display unit 150 to identify the object held by the object 200.

[0019] Fig. 4(A) is a diagram showing an image obtained by photographing the object 200 with a camera (hereinafter referred to as a visible light camera) that photographs the object 200 by detecting reflected waves from the object 200 when visible light is irradiated onto the object 200. Fig. 4(B) is a diagram showing an image obtained by photographing the object 200 with the imaging system 100 of this embodiment. In the examples shown in Figs. 4(A) and 4(B), it is assumed that the object 200 is hiding a knife 310 and a bomb 320 inside its clothes.

[0020] When a visible light camera irradiates object 200 with visible light, the visible light is reflected by the clothes worn by object 200 before reaching knife 310 or bomb 320. In this case, as shown in FIG. 4(A), knife 310 and bomb 320 are not visible in the image captured by the visible light camera, making it difficult for an inspector to identify knife 310 or bomb 320. On the other hand, when imaging system 100 irradiates object 200 with terahertz waves, the terahertz waves pass through the clothes of object 200 and are reflected by knife 310 and bomb 320. In this case, as shown in FIG. 4(B), knife 310 and bomb 320 are displayed in the image captured by imaging system 100, and an inspector can identify from this image that object 200 is carrying knife 310 or bomb 320.

[0021] FIG. 5 is a diagram showing an example of the arrangement of the illumination unit 120 and the imaging unit 130 in the imaging system 100. Note that, hereinafter, the left-right direction in FIG. 5 may be referred to as the X direction, the front-rear direction in FIG. 5 may be referred to as the Y direction, and the up-down direction in FIG. 5 may be referred to as the Z direction. Also, the left side in FIG. 5 may be referred to as the upstream side in the X direction, and the right side in FIG. 5 may be referred to as the downstream side in the X direction. Also, the front side in FIG. 5 may be referred to as the upstream side in the Y direction, and the rear side in FIG. 5 may be referred to as the downstream side in the Y direction. Also, the lower side in FIG. 5 may be referred to as the upstream side in the Z direction, and the upper side in FIG. 5 may be referred to as the downstream side in the Z direction. Also, in the example shown in FIG. 5, the direction in which the illumination unit 120 emits light and the direction in which the imaging unit 130 faces the subject are both the Y direction.

[0022] 5(A), in the imaging system 100, four illumination units 120 and an imaging unit 130 are aligned horizontally in the X direction, with the imaging unit 130 located to the right of each illumination unit 120. Hereinafter, the four illumination units 120 will be referred to as a first illumination unit 120A, a second illumination unit 120B, a third illumination unit 120C, and a fourth illumination unit 120D, respectively. Furthermore, when the first illumination unit 120A, the second illumination unit 120B, the third illumination unit 120C, and the fourth illumination unit 120D are described without any particular distinction, they will be simply referred to as illumination units 120. In the illustrated example, the first illumination unit 120A, the second illumination unit 120B, the third illumination unit 120C, the fourth illumination unit 120D, and the image capture unit 130 are arranged in this order from upstream to downstream in the X direction. The distance from the image capture unit 130 to the fourth illumination unit 120D is distance X1. The distance from the image capture unit 130 to the third illumination unit 120C is distance X2, which is longer than distance X1. The distance from the image capture unit 130 to the second illumination unit 120B is distance X3, which is longer than distance X2. The distance from the image capture unit 130 to the first illumination unit 120A is distance X4, which is longer than distance X3.

[0023] In the example shown in FIG. 5(B), in the imaging system 100, four illumination units 120 and an imaging unit 130 are aligned horizontally in the X direction, with two illumination units 120 located upstream and two downstream of the imaging unit 130 in the X direction. The four illumination units 120 are arranged symmetrically with respect to the imaging unit 130. In the illustrated example, the first illumination unit 120A, the second illumination unit 120B, the imaging unit 130, the third illumination unit 120C, and the fourth illumination unit 120D are aligned in this order from upstream to downstream in the X direction. The distance from the imaging unit 130 to the second illumination unit 120B and the distance from the imaging unit 130 to the third illumination unit 120C are both distance X5. The distance from the imaging unit 130 to the first illumination unit 120A and the distance from the imaging unit 130 to the fourth illumination unit 120D are both distance X6, which is longer than distance X5. In both of the examples shown in FIGS. 5(A) and 5(B), the four illumination units 120 and the imaging units 130 are aligned in positions in the Y direction and Z direction.

[0024] FIG. 6 is a diagram showing the positional relationship between the illumination unit 120, the imaging unit 130, and the object 200. FIG. 6 is a diagram showing the imaging system 100 and the object 200 as viewed from above (upstream in the Z direction) the imaging system 100 and the object 200. The X direction, Y direction, and Z direction in FIG. 6 correspond to the X direction, Y direction, and Z direction in FIG. 5, respectively. The imaging system 100 shown in FIG. 6 is assumed to be the imaging system 100 shown in FIG. 5(B). In FIG. 6, the object 200 is assumed to have a shape symmetrical in the X direction with respect to a position overlapping with the center of the imaging unit 130. 6, the direction in which each illumination unit 120 irradiates terahertz waves is determined in advance. More specifically, first illumination unit 120A and second illumination unit 120B irradiate terahertz waves downstream in the Y direction and downstream in the X direction, and third illumination unit 120C and fourth illumination unit 120D irradiate terahertz waves downstream in the Y direction and upstream in the X direction.

[0025] In the example shown in FIG. 6A, the distance (distance in the Y direction) from each illumination unit 120 and imaging unit 130 to object 200 is assumed to be distance Y1. Here, when first illumination unit 120A irradiates terahertz waves, the irradiated terahertz waves are reflected by object 200. In this case, the incident angle a1 and reflection angle a2 of the terahertz waves with respect to object 200 are equal. Additionally, since terahertz waves have a higher linearity than visible light, when illumination unit 120 irradiates terahertz waves, specular reflection occurs, in which the incident angle and reflection angle are equal. Furthermore, since terahertz waves are less likely to be diffused than visible light, in order to capture images using terahertz waves, the detection device of imaging unit 130 needs to detect specularly reflected terahertz waves. Furthermore, when the reflected terahertz waves are described below, it is assumed that the terahertz waves are specularly reflected terahertz waves.

[0026] 6(A), the terahertz waves irradiated from first illumination unit 120A and reflected by object 200 are incident on the detection device of image capturing unit 130. On the other hand, when second illumination unit 120B irradiates terahertz waves, the irradiated terahertz waves pass downstream in the X direction from image capturing unit 130 after being reflected by object 200, and therefore do not enter the detection device of image capturing unit 130. In this case, first illumination unit 120A and imaging unit 130 are in a positional relationship such that terahertz waves irradiated from illumination unit 120 and reflected by object 200 are detected by a detection device of imaging unit 130. On the other hand, second illumination unit 120B and imaging unit 130 are not in a positional relationship such that terahertz waves irradiated from illumination unit 120 and reflected by object 200 are detected by a detection device of imaging unit 130. For this reason, it is preferable that control unit 110 irradiates object 200 with terahertz waves from first illumination unit 120A, but does not irradiate object 200 with terahertz waves from second illumination unit 120B. Furthermore, although not shown in the figures, third illumination unit 120C and imaging unit 130 are not in a positional relationship where terahertz waves irradiated from illumination unit 120 and reflected by object 200 are detected by a detection device of imaging unit 130. On the other hand, fourth illumination unit 120D and imaging unit 130 are in a positional relationship where terahertz waves irradiated from illumination unit 120 and reflected by object 200 are detected by a detection device of imaging unit 130. For this reason, it is preferable that control unit 110 does not irradiate terahertz waves from third illumination unit 120C to object 200, but irradiates terahertz waves from fourth illumination unit 120D to object 200.

[0027] In the example shown in FIG. 6(B), the distance (distance in the Y direction) from each illumination unit 120 and the image capture unit 130 to the object 200 is assumed to be distance Y2, which is shorter than distance Y1. Here, when the first illumination unit 120A irradiates terahertz waves, the irradiated terahertz waves are reflected by the object 200 and then pass upstream of the image capture unit 130 in the X direction, and therefore do not enter the detection device of the image capture unit 130. Additionally, in the example shown in FIG. 6(B), the distance from each illumination unit 120 and the image capture unit 130 to the object 200 is shorter than in the example shown in FIG. 6(A). Accordingly, the location at which the terahertz waves irradiated from the first illumination unit 120A and reflected by the object 200 enter the imaging system 100 changes. In addition, when the second illumination unit 120B irradiates terahertz waves, the irradiated terahertz waves are reflected by the object 200 and then enter the detection device of the image capture unit 130.

[0028] In this case, first illumination unit 120A and imaging unit 130 are not in a positional relationship where terahertz waves irradiated from illumination unit 120 and reflected by object 200 are detected by a detection device of imaging unit 130. On the other hand, second illumination unit 120B and imaging unit 130 are in a positional relationship where terahertz waves irradiated from illumination unit 120 and reflected by object 200 are detected by a detection device of imaging unit 130. For this reason, it is preferable that control unit 110 does not irradiate terahertz waves from first illumination unit 120A to object 200, but irradiates terahertz waves from second illumination unit 120B to object 200. Although not shown, third illumination unit 120C and imaging unit 130 are positioned such that terahertz waves irradiated from illumination unit 120 and reflected by object 200 are detected by a detection device of imaging unit 130. On the other hand, fourth illumination unit 120D and imaging unit 130 are not positioned such that terahertz waves irradiated from illumination unit 120 and reflected by object 200 are detected by a detection device of imaging unit 130. For this reason, it is preferable that control unit 110 irradiates object 200 with terahertz waves from third illumination unit 120C, but does not irradiate object 200 with terahertz waves from fourth illumination unit 120D.

[0029] In this way, which of the plurality of illumination units 120 irradiates the object 200 and causes the terahertz waves reflected by the object 200 to be incident on the detection device of the imaging unit 130 may differ depending on the positional relationship between the imaging system 100 and the object 200. Therefore, in this embodiment, the control unit 110 determines which of the plurality of illumination units 120 is to irradiate the terahertz waves, depending on the positional relationship between the imaging system 100 and the object 200.

[0030] 6(A) and 6(B), the terahertz waves incident on the object 200 from the irradiation unit 120 and the terahertz waves reflected by the object 200 both travel perpendicular to the Z direction, in other words, horizontally in the X and Y directions. On the other hand, there are cases where the terahertz waves from the irradiation unit 120 are irradiated in a direction that is not horizontal to any of the X, Y, and Z directions. In this case, the control unit 110 determines which of the multiple illumination units 120 is to irradiate the terahertz waves, depending on the positional relationship between the illumination unit 120, the image capture unit 130, and the object 200 in a three-dimensional area defined by coordinates in the X, Y, and Z directions.

[0031] Fig. 7 is a diagram showing an illumination unit management table. The illumination unit management table is a table for managing illumination by the illumination unit 120. The illumination unit management table is stored in the storage unit 170 (see Fig. 1) of the imaging system 100. It is also assumed that the illumination unit management table shown in Fig. 7 shows information relating to the illumination unit 120 shown in Fig. 5(A). The contents of the illumination unit management table will now be described in detail. "Lighting unit" is information that identifies the target lighting unit 120 in the imaging system 100. In the illustrated example, "lighting unit" indicates one of "120A," "120B," "120C," and "120D," which identifies which of the first to fourth lighting units 120A to 120D the information shown in the lighting unit management table targets. The "distance" is the distance from the illumination unit 120 to the image capture unit 130.

[0032] The "irradiation area" is a target area where the irradiation conditions are satisfied. The irradiation conditions are predetermined conditions regarding the positional relationship between the illumination unit 120 and the image capture unit 130. The irradiation conditions are used by the control unit 110 to determine which illumination unit 120 will irradiate the target with terahertz waves. In this embodiment, the irradiation conditions are determined to be a specific positional relationship between the illumination unit 120 and the image capture unit 130. The specific positional relationship is a positional relationship between the illumination unit 120 and the image capture unit 130 where terahertz waves irradiated from the illumination unit 120 and reflected by the target are incident on the detection device of the image capture unit 130. In the illustrated example, the "irradiation area" indicates the target area where the irradiation conditions are satisfied as a three-dimensional range defined by coordinates in the X, Y, and Z directions.

[0033] The "irradiation level" indicates an index showing the intensity of light emitted by the terahertz waves irradiated from the illumination unit 120. The larger the value shown in the "irradiation level," the higher the intensity of light emitted by the terahertz waves irradiated from the illumination unit 120. Also, as shown in the figure, the longer the distance from the imaging unit 130 to the "illumination unit," the higher the "irradiation level" associated with it. An example of the contents recorded in the lighting unit management table will be described below. The first lighting unit 120A, "120A," is associated with "X4" as the "distance," "x1, y1, z1 to xa, ya, za" as the "illumination area," and "4" as the "illumination level." The information shown in the illumination unit management table may be information input to the imaging system 100 by a user of the imaging system 100, or may be information specified by the control unit 110.

[0034] 8(A) and 8(B) are flowcharts showing the flow of the control process. The control process is a process in which the control unit 110 of the imaging system 100 controls the illumination unit 120 and the imaging unit 130. In this embodiment, the control process is started when, for example, a user of the imaging system 100, such as an inspector, operates an operation unit (not shown) of the imaging system 100. Alternatively, the control process may be started when, for example, the imaging system 100 is powered on. In this embodiment, each step in the control process is realized when the CPU 101 (see FIG. 2) loads a program stored in the storage device 102 into the memory 103 and executes it. The control unit 110 activates the imaging unit 130 and the detection unit 180 (step (hereinafter sometimes referred to as "S") 101). More specifically, the control unit 110 puts the imaging unit 130 into a state where it can capture an image, and causes the detection unit 180 to detect the target object.

[0035] The control unit 110 determines whether the detection unit 180 has detected an object (S102). A case in which the detection unit 180 has not detected an object is when the object is not present within a range that can be detected by the detection unit 180. As long as the negative result is continued in step 102, the control unit 110 repeats the processing of step 102. When the control unit 110 determines that the detection unit 180 has detected an object (Yes in S102), the control unit 110 determines, for each illumination unit 120, whether the positional relationship between the illumination unit 120 and the image capture unit 130 satisfies the illumination condition (S103). The control unit 110 determines whether the positional relationship between the illumination unit 120 and the image capture unit 130 satisfies the illumination condition based on whether the target area is included in the range of the area indicated in the "illumination area" in the illumination unit management table. Note that the target area in this case is the area detected by the detection unit 180 as the area where the object is located.

[0036] When the control unit 110 determines that the positional relationship between the illumination unit 120 and the image capture unit 130 does not satisfy the illumination condition for any of the illumination units 120 (No in S103), the control unit 110 determines whether to allow the detection unit 180 to continue detecting the object (S104). In this case, information indicating that the illumination condition is not satisfied and information for allowing the user to select whether to allow the detection unit 180 to continue detecting the object may be displayed on the display unit 150 (see FIG. 1). Then, the control unit 110 may determine whether to allow the detection unit 180 to continue detecting the object in response to a user's operation of an operation unit (not shown) of the image capture system 100.

[0037] When control unit 110 determines not to allow detection unit 180 to continue detecting the object (No in S104), it terminates the operation of imaging unit 130 and detection unit 180 (S105), and the control process ends. More specifically, control unit 110 sets imaging unit 130 to a state in which it is not possible to capture an image, and sets detection unit 180 to a state in which it is not possible to detect the object. Furthermore, if control unit 110 determines that detection unit 180 should continue detecting the object (Yes in S104), the processing from step 102 is performed again.

[0038] Furthermore, when the control unit 110 determines that the positional relationship between the illumination unit 120 and the image capturing unit 130 satisfies the irradiation condition for any of the illumination units 120 (Yes in S103), it turns on the illumination unit 120 that satisfies the irradiation condition (S106). More specifically, the control unit 110 controls the illumination unit 120 that is located at a position that satisfies the irradiation condition to irradiate terahertz waves. As a result, the terahertz waves irradiated from the illumination unit 120 that satisfies the irradiation condition and reflected by the object are incident on the detection device of the image capturing unit 130, and the image capturing unit 130 captures an image of the object, thereby obtaining an image showing an object held by the object. Furthermore, at this time, the control unit 110 controls the intensity of the light emitted by the terahertz waves irradiated from the illumination unit 120 that is located at a position that satisfies the irradiation condition to the image capturing unit 130, depending on the distance from the illumination unit 120 that satisfies the irradiation condition to the image capturing unit 130. More specifically, the control unit 110 controls the illumination unit 120 located at a position that satisfies the irradiation condition to irradiate terahertz waves at the "irradiation level" defined in the illumination unit management table (see FIG. 7). The target illumination unit 120 that satisfies the irradiation condition may be referred to as the target unit. Furthermore, if there are multiple illumination units 120 at positions that satisfy the irradiation conditions, the control unit 110 causes all illumination units 120 that satisfy the irradiation conditions to emit terahertz waves.

[0039] The control unit 110 determines whether the detection unit 180 has detected the object again (S107). More specifically, the control unit 110 causes the detection unit 180 to detect the object again, and determines whether the object has been detected by the detection unit 180 again. If the object is detected again by the detection unit 180 (Yes in S107), the control unit 110 determines whether or not the positional relationship between the object, the imaging unit 130, and the object has changed (S108). The control unit 110 determines whether or not the positional relationship has changed depending on whether or not the area detected by the detection unit 180 as the area where the object is located is no longer included in the range of the area indicated in the "irradiation area" of the illumination unit management table for the illumination unit 120, which is the object.

[0040] If control unit 110 determines that the positional relationship between the target portion, imaging unit 130, and the target object has not changed (No in S108), the processing from step 107 is repeated. Furthermore, if the control unit 110 determines that the positional relationship between the target portion, the imaging unit 130, and the object has changed (Yes in S108), it determines for each lighting unit 120 whether the positional relationship between the lighting unit 120 and the imaging unit 130 satisfies the illumination conditions (S109).

[0041] If a negative result is obtained in step 107 or step 109, control unit 110 turns off the target unit that was turned on in step 106 (S110). More specifically, control unit 110 ends the irradiation of terahertz waves by illumination unit 120 that was irradiating terahertz waves in step 106. The control unit 110 determines whether or not to cause the detection unit 180 to continue detecting the object (S111). When the control unit 110 determines not to cause the detection unit 180 to continue detecting the object (No in S111), the control unit 110 ends the operation of the imaging unit 130 and the detection unit 180 (S112), and the control processing ends. The processing in step 111 and the processing in step 112 are the same as the processing in step 104 and the processing in step 105, respectively. Furthermore, if control unit 110 determines that detection unit 180 should continue detecting the object (Yes in S111), the process from S102 is performed again.

[0042] Furthermore, when the control unit 110 determines that the positional relationship between the illumination unit 120 and the image capturing unit 130 satisfies the irradiation condition for any of the illumination units 120 (Yes in S109), the control unit 110 turns off the target unit that was turned on in step 106 (S113). The processing in step 113 is the same as the processing in step 110. The control unit 110 turns on the target unit that newly satisfies the irradiation condition (S114). More specifically, the control unit 110 causes the terahertz wave to be emitted from the illuminating unit 120 that is located at a position among the plurality of illuminating units 120 that newly satisfies the irradiation condition. As a result, even if the positional relationship among the illuminating unit 120, the image capturing unit 130, and the target changes, the terahertz wave emitted from the new illuminating unit 120 and reflected by the target is incident on the image capturing unit 130. After step 114, the processing from step 107 is repeated.

[0043] As described above, the control unit 110 controls the illumination unit 120 so that the positional relationship between the illumination unit 120 that illuminates the target area and the imaging unit 130 that images the target area satisfies the illumination conditions, depending on the positional relationship between the target area to be imaged by the imaging unit 130 and the imaging unit 130. In this case, even if the positional relationship between the lighting unit 120, the imaging unit 130, and the target area is not the same each time shooting is performed, shooting can be achieved under a positional relationship that satisfies the illumination conditions between the lighting unit 120 that illuminates the target area and the imaging unit 130 that photographs the target area.

[0044] In this embodiment, the illumination unit 120 includes a plurality of illumination units 120 at different positions, and the control unit 110 controls the target area to be irradiated with light from an illumination unit 120 that is located at a position where the irradiation conditions are satisfied among the plurality of illumination units 120. In this case, the power consumed by the illumination unit 120 can be reduced compared to when terahertz waves are irradiated from an illumination unit 120 that is located at a position where the irradiation conditions are not satisfied.

[0045] Furthermore, when the positional relationship between the target area and the image capturing unit 130 changes, the control unit 110 controls the illumination unit 120 so that the illumination condition is satisfied after the change (see steps 109 to 114 in FIG. 8(B)). In this case, even when the positional relationship between the illumination unit 120, the image capturing unit 130, and the target area changes, it is possible to realize imaging under a positional relationship that satisfies the illumination condition between the illumination unit 120 that illuminates the target area and the image capturing unit 130 that captures the target area.

[0046] Furthermore, when the positional relationship between any of the illumination units 120 and the image capturing unit 130 does not satisfy the irradiation condition, the control unit 110 controls the specific illumination unit 120 so that the positional relationship between the specific illumination unit 120 that has not irradiated the target area and the image capturing unit 130 satisfies the irradiation condition. An example of the specific illumination unit 120 is the illumination unit 120 that is newly irradiated with terahertz waves in step 114 of the control process (see FIG. 8(B)). In this case, even if the positional relationship between any of the lighting units 120 and the imaging unit 130 does not satisfy the illumination conditions, it is possible to achieve imaging under a positional relationship that satisfies the illumination conditions between the lighting unit 120 that illuminates the target area and the imaging unit 130 that images the target area.

[0047] The positional relationship between the illumination unit 120 and the image capture unit 130 that satisfies the illumination condition is determined by the area where the illumination unit 120 is located, the area where the image capture unit 130 is located, and the target area. Therefore, the illumination condition can also be understood as a condition determined regarding the positional relationship between the illumination unit 120, the image capture unit 130, and the target area.

[0048] Furthermore, in this embodiment, the positional relationship that satisfies the irradiation condition is defined as a relationship between areas in three dimensions, but the present invention is not limited to this. In the imaging system 100, the illumination units 120, the imaging unit 130, and the target area may be located in a two-dimensional area (two-dimensionally defined by coordinates in the X and Y directions in the example shown in FIG. 5), as shown in FIG. 5(A) and FIG. 5(B). In this case, the positional relationship that satisfies the illumination condition may be determined as a relationship between the areas in two dimensions. An example of the relationship between the areas in two dimensions is the relationship between the distance from the imaging unit 130 to the target area.

[0049] An example of determining the positional relationship in which the illumination condition is satisfied as a relationship of the distance from the image capture unit 130 to the target area will be described. As shown in FIGS. 6A and 6B, the shorter the distance from the image capture unit 130 to the target area, the shorter the distance from the image capture unit 130 to the illumination unit 120 in a position in which the illumination condition is satisfied. Therefore, the distance from the image capture unit 130 to the target area as the positional relationship in which the illumination condition is satisfied may be determined according to the distance from the illumination unit 120 to the image capture unit 130. In this case, in the illumination unit management table (see FIG. 7), for each "illumination unit," the range of the distance from the image capture unit 130 to the target area in which the illumination condition is satisfied may be indicated in the "illumination area" according to the "distance" from the illumination unit 120 to the image capture unit 130. Then, in the control process (see FIG. 8), the control unit 110 may determine that the "illumination unit" associated with the "illumination area" including the distance from the image capture unit 130 to the target object 200 is the illumination unit 120 in a position in which the illumination condition is satisfied. Furthermore, the positional relationship in which the illumination condition is satisfied is not limited to the relationship of the distance from the image capture unit 130 to the target area. As shown in the examples of Figures 6(A) and 6(B), there are cases in which the difference between the distance from the illumination unit 120 to the target area and the distance from the image capture unit 130 to the target area is small. Therefore, the distance from the illumination unit 120 to the target area may be determined as the positional relationship in which the illumination condition is satisfied. Furthermore, the distance from the image capture system 100 to the target area may be determined as the positional relationship in which the illumination condition is satisfied.

[0050] As described above, in this embodiment, the plurality of illumination units 120 include a first illumination unit 120 whose distance to the image capture unit 130 is a first distance and a second illumination unit 120 whose distance to the image capture unit 130 is longer than the first distance. The target area includes a first target area whose distance to the image capture unit 130 is a second distance and a second target area whose distance to the image capture unit 130 is longer than the second distance. The control unit 110 controls the first illumination unit 120 to irradiate the terahertz waves when the target area is the first target area, and controls the second illumination unit 120 to irradiate the terahertz waves when the target area is the second target area. The first distance can be distance X5 (see FIG. 5B). The first illumination unit 120 can be the second illumination unit 120B or the third illumination unit 120C in the example shown in FIG. 5B. Furthermore, examples of the second illumination unit 120 include the first illumination unit 120A and the fourth illumination unit 120D in the example shown in FIG. 5(B). Furthermore, examples of the second distance include the distance Y2 (see FIG. 6(B)). Furthermore, examples of the first target area include the area where the object 200 is located in the example shown in FIG. 6(B). Furthermore, examples of the second target area include the area where the object 200 is located in the example shown in FIG. 6(A). In this case, even if the distance from the imaging unit 130 to the target area is not the same each time photography is performed, photography is performed under a positional relationship between the illumination unit 120 and the imaging unit 130 that satisfies the illumination conditions for the illumination unit 120 that illuminates the target area and the imaging unit 130 that photographs the target area.

[0051] Furthermore, control unit 110 controls the intensity of light emitted by terahertz waves to be higher when illuminating unit 120 irradiates the second target area with terahertz waves than when illuminating unit 120 irradiates the first target area with terahertz waves. In this case, non-uniformity in the accuracy of images obtained by capturing is suppressed compared to when the intensity of light emitted by terahertz waves is the same regardless of the distance from illumination unit 120, which irradiates the terahertz waves, to imaging unit 130.

[0052] Furthermore, the plurality of illumination units 120 and the image capturing unit 130 are provided in one direction. In this case, it becomes easier to associate the illumination unit 120 that satisfies the irradiation conditions with the image capturing unit 130 depending on the positional relationship between the image capturing unit 130 and the target area.

[0053] Fig. 9 is a diagram showing a first modification of the arrangement of the illumination unit 120 and the imaging unit 130 in the imaging system 100. Fig. 9 is a diagram of the imaging system 100 and the object 200 viewed from above (upstream in the Z direction) the imaging system 100 and the object 200. The X direction, Y direction, and Z direction in Fig. 9 correspond to the X direction, Y direction, and Z direction in Fig. 5, respectively. The arrangement of the illumination unit 120 and the imaging unit 130 shown in Fig. 9 is similar to the arrangement shown in Fig. 6(B) in that the imaging unit 130 is sandwiched in the X direction between the first illumination unit 120A and the second illumination unit 120B and the third illumination unit 120C and the fourth illumination unit 120D. However, the arrangement of the illumination unit 120 and the imaging unit 130 shown in Fig. 9 differs from the arrangement shown in Fig. 6(B) in the positional relationship between the illumination unit 120 and the imaging unit 130 in the Y direction. More specifically, in the example shown in Fig. 9, the second illumination unit 120B and the third illumination unit 120C are located downstream in the Y direction from the imaging unit 130. Furthermore, the first illumination unit 120A and the fourth illumination unit 120D are located downstream in the Y direction from the second illumination unit 120B and the third illumination unit 120C.

[0054] Here, the first illumination unit 120A, the second illumination unit 120B, the third illumination unit 120C, and the fourth illumination unit 120D are not arranged on a straight line with respect to the imaging unit 130. In other words, a straight line L1 passing through the first illumination unit 120A and the imaging unit 130, a straight line L2 passing through the second illumination unit 120B and the imaging unit 130, a straight line L3 passing through the third illumination unit 120C and the imaging unit 130, and a straight line L4 passing through the fourth illumination unit 120D and the imaging unit 130 all intersect with each other. Note that the straight line passing through the illumination unit 120 and the imaging unit 130 refers to a straight line passing through the center of the illumination unit 120 and the center of the imaging unit 130.

[0055] As described above, in the example shown in Fig. 9, the plurality of illumination units 120 include a first illumination unit 120 and a second illumination unit 120, and the second illumination unit 120 is provided at a position that is not on a line that passes through the first illumination unit 120 and the imaging unit 130. The first illumination unit 120 may be any of the four illumination units 120 shown in Fig. 9. Furthermore, the second illumination unit 120 may be any illumination unit 120 that is different from the first illumination unit 120 among the illumination units 120 shown in Fig. 9. In this case, it is possible to realize illumination of the illumination units 120 corresponding to the object 200 that does not have a linear shape. In particular, in the example shown in Fig. 9, the distance between each illumination unit 120 and the object 200 is shortened by the amount of the arrangement of the illumination units 120 corresponding to the shape of the person that is the object 200, thereby improving the accuracy of imaging by the imaging system 100. Furthermore, when multiple illumination units 120 are provided in an arc shape as shown in Fig. 9, this contributes to a reduction in the size of the imaging system 100 compared to when multiple illumination units 120 are arranged in a straight line.

[0056] 5(A) and 5(B), the first illumination section 120A, the second illumination section 120B, the third illumination section 120C, and the fourth illumination section 120D are provided on a straight line with respect to the image capturing section 130. In other words, the line passing through the first illumination section 120A and the image capturing section 130, the line passing through the second illumination section 120B and the image capturing section 130, the line passing through the third illumination section 120C and the image capturing section 130, and the line passing through the fourth illumination section 120D and the image capturing section 130 do not intersect with each other. 9 are arranged in order in the X direction. That is, the illumination units 120 and the imaging unit 130 shown in FIG. 9 can be regarded as an example of being arranged in one direction.

[0057] 5(A), 5(B), and 9, all of the illumination units 120 provided in the imaging system 100 are arranged along one direction, but this is not limiting. As long as at least two of the illumination units 120 and the imaging unit 130 among the irradiation units 120 provided in the imaging system 100 are arranged along one direction, the other illumination units 120 may be arranged not along one direction.

[0058] Fig. 10 is a diagram showing a second modification of the arrangement of the illumination unit 120 and the imaging unit 130 in the imaging system 100. Fig. 10 is a diagram showing the imaging system 100 as viewed from the upstream side in the Y direction relative to the imaging system 100. The X direction, Y direction, and Z direction in Fig. 10 correspond to the X direction, Y direction, and Z direction in Fig. 5, respectively. 10A, the imaging system 100 is provided with a plurality of groups of illumination units 120 that are divided according to the distance from the imaging unit 130 to the illumination units 120. More specifically, the imaging system 100 is provided with a first group of illumination units 1201, a second group of illumination units 1202, and a third group of illumination units 1203. The illumination units 120 belonging to the first group of illumination units 1201 are illumination units 120 that are located at a distance Z1 from the imaging unit 130. The illumination units 120 belonging to the second group of illumination units 1202 are illumination units 120 that are located at a distance Z2 from the imaging unit 130 that is longer than the distance Z1. The illumination units 120 belonging to the third group of illumination units 1203 are illumination units 120 that are located at a distance Z3 from the imaging unit 130 that is longer than the distance Z2. Each group includes eight illumination units 120 arranged at equal intervals in the circumferential direction of the imaging unit 130. The imaging unit 130 and each illumination unit 120 are aligned in the Y direction.

[0059] Here, for example, when the distance from the imaging system 100 to the target area is relatively short, the control unit 110 causes each illumination unit 120 belonging to the first group of illumination units 1201 to irradiate terahertz waves, as shown in Fig. 10(B). When the illumination unit 120 located at a position where the irradiation condition is satisfied is the first group of illumination units 1201, it is assumed that the target area is an area upstream or downstream in the Y direction from the imaging system 100. In addition, there is also the case where the target area is an area between the imaging unit 130 and the first group of illumination units 1201 in the X direction or Z direction.

[0060] 10C , the second group of illumination units 1202 irradiates the target area with terahertz waves. The second group of illumination units 1202 irradiates the target area with terahertz waves, as shown in FIG. 10C. The second group of illumination units 1202 irradiates the target area with terahertz waves, as shown in FIG. 10C. The second group of illumination units 1202 irradiates the target area with terahertz waves. ... 10D, the control unit 110 controls each of the illumination units 120 belonging to the third group of illumination units 1203 to irradiate terahertz waves. The third group of illumination units 1203 is the illumination unit 120 located at a position where the irradiation condition is satisfied, assuming that the target area is farther from the imaging system 100 than when the second group of illumination units 1202 irradiates terahertz waves. In addition, the target area may be an area upstream or downstream of the imaging system 100 in the Y direction, and between the imaging unit 130 and the third group of illumination units 1203 in the X direction or Z direction.

[0061] 10, each of the plurality of illumination units 120 belongs to one of the plurality of groups divided according to the distance from the imaging unit 130 to the illumination units 120. Then, the control unit 110 controls the illumination units 120 belonging to the group among the plurality of groups that is located at a position where the irradiation condition is satisfied to irradiate terahertz waves. In this case, the accuracy of imaging is improved compared to a configuration in which terahertz waves are irradiated from only a single illumination unit 120. 10, the illumination units 120 of each group are arranged to surround the imaging unit 130. In this case, the target object can be irradiated with terahertz waves from various angles, making it easier to obtain an image showing an object held by the target object regardless of the orientation of the target object.

[0062] In the present embodiment, the control unit 110 performs control so that terahertz waves are not emitted from the illumination unit 120 located at a position where the irradiation condition is not satisfied, but the present invention is not limited to this. For example, the control unit 110 may perform control so that terahertz waves are emitted from the illumination unit 120 that is closer to the image capture unit 130 than the illumination unit 120 located at a position where the irradiation condition is satisfied. Furthermore, the illumination unit 120 may be able to change the area onto which the terahertz waves are irradiated. In this case, for each area onto which the illumination unit 120 can irradiate the terahertz waves, a target area that satisfies the irradiation conditions may be indicated in the "irradiation area" of the illumination unit management table (see FIG. 7). Furthermore, the target areas for which the illumination conditions are satisfied among the plurality of illumination units 120 may at least partially overlap, or the target areas for which the illumination conditions are satisfied may not overlap.

[0063] Furthermore, the configuration for realizing irradiation of terahertz waves from the illumination unit 120 under the positional relationship between the illumination unit 120 and the image capturing unit 130 that satisfies the irradiation conditions is not limited to the above-described example. The imaging system 100 may be provided with multiple imaging units 130, each located at a different position. The control unit 110 determines the imaging unit 130, among the multiple imaging units 130, located in an area where the irradiation condition is satisfied as the imaging unit 130 to be used to capture the target area. The control unit 110 then causes the illumination unit 120 located in the area where the irradiation condition is satisfied to emit terahertz waves, and causes the imaging unit 130 located in the area where the irradiation condition is satisfied to capture the target area. That is, the control unit 110 may control the imaging unit 130 according to the positional relationship between the imaging unit 130 and the target area to be captured by the imaging unit 130, so that the positional relationship between the illumination unit 120 and the imaging unit 130 satisfies the irradiation condition. Furthermore, when the positional relationship between the target area and the imaging unit 130 changes, the control unit 110 may control the imaging unit 130 to use the imaging unit 130 located in an area where the irradiation condition is satisfied after the change.

[0064] Furthermore, the imaging system 100 may be provided with a plurality of illumination units 120 each located at a different position, and a plurality of imaging units 130 each located at a different position. Then, the control unit 110 may determine, among the plurality of illumination units 120 and the plurality of imaging units 130, the illumination unit 120 and the imaging unit 130 located in an area where the irradiation condition is satisfied, as the illumination unit 120 and the imaging unit 130 to be used to photograph the object.

[0065] Next, an imaging system 100 according to a second embodiment will be described. The imaging system 100 of the second embodiment is similar to the imaging system 100 of the first embodiment in that the illumination unit 120 is controlled so that the positional relationship between the illumination unit 120, the imaging unit 130, and the target area satisfies the irradiation conditions. However, the imaging system 100 of the second embodiment differs from the imaging system 100 of the first embodiment in the method of controlling the illumination unit 120 to satisfy the irradiation conditions. Specifically, the imaging system 100 of the first embodiment controls the illumination unit 120 that irradiates terahertz waves so that the illumination unit 120 located at a position where the irradiation conditions are satisfied among the multiple illumination units 120 irradiates terahertz waves. In contrast, the imaging system 100 of the second embodiment moves the illumination unit 120 to a position where the irradiation conditions are satisfied, and then irradiates terahertz waves from the moved illumination unit 120. In other words, in the first embodiment, the positional relationship between each lighting unit 120 and the imaging unit 130 was fixed, whereas in the second embodiment, the positional relationship between the lighting unit 120 and the imaging unit 130 is not fixed.

[0066] Fig. 11 is a diagram showing the configuration of an imaging system 100 according to the second embodiment. Note that, for the second embodiment, configurations different from those of the first embodiment will be described, and descriptions of configurations that are the same as those of the first embodiment will be omitted. Also, the X direction, Y direction, and Z direction in Fig. 11 correspond to the X direction, Y direction, and Z direction in Fig. 5, respectively. 11, the imaging system 100 of the second embodiment is provided with one illumination unit 120 and one imaging unit 130. The illumination unit 120 is provided with a drive unit 121 that drives the illumination unit 120, and the control unit 110 can move the illumination unit 120 within the range of an area R in the imaging system 100 by driving the drive unit 121. In this way, the illumination unit 120 can be positioned in an area including the periphery of the imaging unit 130 by moving in the X direction and the Z direction.

[0067] Furthermore, in this embodiment, the control unit 110 manages the position of the illumination unit 120 and the position of the imaging unit 130. More specifically, the control unit 110 manages the position of the illumination unit 120 in the imaging system 100, the position of the imaging unit 130 in the imaging system 100, and the positional relationship between the illumination unit 120 and the imaging unit 130. Note that the positional relationship between the illumination unit 120 and the imaging unit 130 also includes the distance from the illumination unit 120 to the imaging unit 130. The control unit 110 manages the position of the illumination unit 120 and the position of the imaging unit 130 by acquiring information indicating the positions of the illumination unit 120 and the imaging unit 130. The information indicating the positions of the illumination unit 120 and the imaging unit 130 may be generated by the illumination unit 120 and the imaging unit 130, or may be acquired by the acquisition unit 160 as information input by the user of the imaging system 100 and stored in the storage unit 170. The area in which the illumination unit 120 moves is not limited to the range shown in the figure. The illumination unit 120 may be movable in the Y direction in the imaging system 100.

[0068] FIG. 12 is a diagram illustrating an illumination unit management table according to the second embodiment. The lighting unit management table shown in FIG. 12 indicates "area" and "illumination level." The "range" is the range of distance D, which is the distance from illumination unit 120 to imaging unit 130 when illumination unit 120 irradiates terahertz waves. In the "irradiation level" field, an index indicating the intensity of light emitted by the terahertz waves irradiated from the illumination unit 120 is shown.

[0069] In the illumination unit management table of the second embodiment, a "range" and an "irradiation level" are associated with each other so that the intensity of light emitted by the terahertz waves irradiated from the illumination unit 120 increases as the distance D from the irradiation unit 120 to the image capturing unit 130 increases. When the control unit 110 causes the illumination unit 120 to irradiate terahertz waves, the control unit 110 causes the illumination unit 120 to irradiate the terahertz waves at an "irradiation level" according to the "range" to which the distance D from the irradiation unit 120 to the image capturing unit 130 belongs, based on the illumination unit management table.

[0070] 13A and 13B are flowcharts showing the flow of control processing in the second embodiment. The control unit 110 activates the imaging unit 130 and the detection unit 180 (S201), and determines whether the detection unit 180 has detected an object (S202). The processing in step 201 and the processing in step 202 are the same as the processing in step 101 and the processing in step 102, respectively, in the control processing shown in Fig. 8. Furthermore, while a negative result is continued in step 202, the control unit 110 repeats the processing in step 202.

[0071] When the control unit 110 determines that the detection unit 180 has detected an object (Yes in S202), the control unit 110 specifies an area where the illumination condition is satisfied for the position of the illumination unit 120, based on the positional relationship between the object and the image capture unit 130 (S203). In other words, the control unit 110 specifies in which area the illumination unit 120 should be located to satisfy the illumination condition, based on the positional relationship between the object and the image capture unit 130. The control unit 110 specifies the positional relationship between the object and the image capture unit 130, based on the position of the object detected by the detection unit 180, and specifies an area where the illumination condition is satisfied for the position of the illumination unit 120, based on the specified positional relationship. The control unit 110 determines whether or not the area identified as the position of the illumination unit 120 where the irradiation condition is satisfied is included in a range where the illumination unit 120 can move (S204). More specifically, the control unit 110 makes the determination in step 204 based on whether or not the area identified in step 203 is included in area R shown in FIG.

[0072] When the control unit 110 determines that the area of ​​the illumination unit 120 where the irradiation condition is satisfied is not included in the range where the illumination unit 120 can move (No in S204), the control unit 110 determines whether or not to cause the detection unit 180 to continue detecting the object (S205). When the control unit 110 determines that the detection unit 180 should not continue detecting the object (No in S205), the control unit 110 terminates the operation of the imaging unit 130 and the detection unit 180 (S206). The processing in step 205 and the processing in step 206 are the same as the processing in step 104 and the processing in step 105, respectively, in the control processing shown in FIG. Furthermore, if the control unit 110 determines that the detection unit 180 should continue detecting the object 200 (Yes in S205), the process from S202 is performed again.

[0073] Furthermore, when the control unit 110 determines that the area of ​​the illumination unit 120 where the irradiation condition is satisfied is included in the range where the illumination unit 120 can move (Yes in S204), the control unit 110 proceeds to the next step. The control unit 110 determines whether the area of ​​the illumination unit 120 where the illumination condition is satisfied is the area where the illumination unit 120 is currently located (S207).

[0074] If the control unit 110 determines that the area of ​​the lighting unit 120 where the illumination conditions are satisfied is not the area where the lighting unit 120 is currently located (No in S207), the control unit 110 moves the lighting unit 120 to the area where the illumination conditions are satisfied (S208). If a positive result is obtained in step 207, or after step 208, the control unit 110 turns on the illumination unit 120, which is the target unit that satisfies the irradiation condition, to cause the illumination unit 120 to irradiate the terahertz wave (S209). At this time, the control unit 110 also irradiates the terahertz wave at an "irradiation level" according to the "distance" from the illumination unit 120 to the image capturing unit 130, based on the illumination unit management table shown in FIG.

[0075] The control unit 110 determines whether the detection unit 180 has detected the target object again (S210). The process in step 210 is the same as the process in step 107 in the control process shown in FIG. If the object is detected again by the detection unit 180 (Yes in S210), the control unit 110 newly identifies an area where the irradiation condition is satisfied as the position of the illumination unit 120, based on the positional relationship between the object and the imaging unit 130 (S211).

[0076] The control unit 110 determines whether the area newly identified as the position of the illumination unit 120 where the irradiation condition is satisfied has changed from the area identified in step 203 (S212). If the area of ​​the illumination unit 120 where the irradiation condition is satisfied has not changed (No in S212), the processing from step 210 is repeated. Furthermore, if the control unit 110 determines that the area of ​​the illumination unit 120 in which the illumination conditions are satisfied has changed (Yes in S212), it determines whether the new area in which the illumination conditions are satisfied is included in the range in which the illumination unit 120 can move (S213).

[0077] When the control unit 110 determines that the new region where the irradiation condition is satisfied is not included in the range where the illumination unit 120 can move (No in S213), the control unit 110 turns off the target unit that was turned on in step 209 (S214). More specifically, the control unit 110 causes the illumination unit 120 to end irradiation of the terahertz wave. Control unit 110 determines whether or not to cause detection unit 180 to continue detecting the object (S215). When control unit 110 determines not to cause detection unit 180 to continue detecting the object (No in S215), it ends the operation of imaging unit 130 and detection unit 180 (S216), and the control processing ends. The processing in step 215 and the processing in step 216 are the same as the processing in step 205 and the processing in step 206, respectively. Furthermore, if control unit 110 determines that detection unit 180 should continue detecting the object (Yes in S215), the process from S202 is performed again.

[0078] Furthermore, when the control unit 110 determines that the new area where the illumination condition is satisfied is included in the range where movement by the illumination unit 120 is possible (Yes in S213), it moves the illumination unit 120 to the new area where the illumination condition is satisfied (S217). In this way, even if the positional relationship between the illumination unit 120 and the imaging unit 130 no longer satisfies the illumination condition due to a change in the area of ​​the illumination unit 120 where the illumination condition is satisfied (see S212), the illumination unit 120 moves to the new area where the illumination condition is satisfied. After this, the process is repeated from step 210.

[0079] As described above, in this embodiment, control unit 110 moves illumination unit 120 so that the positional relationship between illumination unit 120 and imaging unit 130 satisfies the illumination condition, depending on the positional relationship between imaging unit 130 and the target area photographed by imaging unit 130. With this configuration, even if the positional relationship between illumination unit 120, imaging unit 130, and the target area is not the same every time photographing is performed, photographing can be achieved under a positional relationship that satisfies the illumination condition between illumination unit 120 that illuminates the target area and imaging unit 130 that photographs the target area. Furthermore, when the positional relationship between the target area and the imaging unit 130 changes, the control unit 110 controls the illumination unit 120 so that the illumination conditions are satisfied after the change (see steps 212 to 217 in FIG. 13(B)).

[0080] Furthermore, when the positional relationship between the illumination unit 120 and the image capturing unit 130 does not satisfy the irradiation condition, the control unit 110 controls the specific illumination unit 120 that has not irradiated the target area so that the positional relationship between the illumination unit 120 and the image capturing unit 130 satisfies the irradiation condition. Here, the "specific illumination unit 120 that has not irradiated the target area" also includes, in the case where the target area changes (see S212), the illumination unit 120 that irradiated the target area with terahertz waves before the change.

[0081] In this embodiment, the configuration for realizing irradiation of terahertz waves from the illumination unit 120 under the positional relationship between the illumination unit 120 and the image capturing unit 130 that satisfies the irradiation conditions is not limited to the example described above. In the imaging system 100, the imaging unit 130 may be provided so as to be movable. In this case, the control unit 110 identifies an area where the irradiation condition is satisfied as the position of the imaging unit 130 from the positional relationship between the illumination unit 120 and the target area, moves the imaging unit 130 to the identified area, and then causes the illumination unit 120 to irradiate the terahertz wave. In this way, the control unit 110 may move the imaging unit 130 according to the positional relationship between the imaging unit 130 and the target area to be photographed by the imaging unit 130, so that the positional relationship between the illumination unit 120 and the imaging unit 130 satisfies the irradiation condition. Furthermore, both the illumination unit 120 and the image capturing unit 130 may be movable. In this case, the control unit 110 identifies an area where the irradiation conditions are satisfied for the positions of the illumination unit 120 and the image capturing unit 130 based on the target area, moves the illumination unit 120 and the image capturing unit 130 to the identified area, and then causes the illumination unit 120 to irradiate the terahertz wave.

[0082] Furthermore, in this embodiment, the control unit 110 specifies the positional relationship between the object and the image capturing unit 130 based on the position of the object detected by the detection unit 180, but this is not limiting. The detection unit 180 may detect the position of the object, and may specify the positional relationship between the object and the image capturing unit 130 based on the detection result, and transmit information indicating the specified positional relationship to the control unit 110.

[0083] Furthermore, in the first and second embodiments, the positional relationship between the illumination unit 120 and the image capturing unit 130, in which the terahertz waves irradiated from the illumination unit 120 and reflected by the object are incident on the detection device of the image capturing unit 130, has been described as the irradiation condition, but this is not limiting. For example, the irradiation condition may be the positional relationship between the illumination unit 120 and the image capturing unit 130, in which the terahertz waves irradiated from the illumination unit 120 and reflected by the object are incident on a predetermined range from the detection device of the image capturing unit 130. The predetermined range may be any range, but is, for example, a range with a radius of 10 cm centered on the detection device.

[0084] Furthermore, the imaging system 100 of the first and second embodiments has been described as having a configuration including the holding unit 210, but the present invention is not limited to this. The imaging system 100 may be configured without the holding unit 210 and may be fixed to a predetermined location. In this case, the imaging system 100 may be a surveillance camera that controls the lighting unit 120 and the imaging unit 130 so that the illumination conditions are satisfied according to the positional relationship between the imaging unit 130 and a moving object such as a person.

[0085] Furthermore, the imaging system 100 of the first and second embodiments may be a mobile-mounted camera mounted on a mobile object such as a car or a drone. Furthermore, the imaging system 100 may be a wearable camera mounted on an object worn by a person, such as an HMD (Head Mounted Display) or smart glasses. Even when the imaging system 100 moves, the imaging system 100 may control the illumination unit 120 and the imaging unit 130 so that the illumination conditions are satisfied according to the positional relationship between the target area and the imaging unit 130.

[0086] Furthermore, the imaging system 100 of the first and second embodiments is configured so that the position of the object is identified by the detection unit 180, but the present invention is not limited to this. Information indicating the position of the object may be transmitted to the imaging system 100, acquired by the acquisition unit 160, and then stored in the storage unit 170. Then, the control unit 110 may identify the position of the object from the information stored in the storage unit 170.

[0087] Although the illumination unit 120 of the present embodiment has been described as emitting terahertz waves, the present invention is not limited to this. The illumination unit 120 may emit waves of a frequency other than terahertz waves. Even in this case, the control unit 110 may control the illumination unit 120 and the image capture unit 130 so that the irradiation conditions are satisfied according to the positional relationship between the object and the image capture unit 130.

[0088] The present invention also includes cases where a software program that realizes the functions of each of the above-described embodiments is supplied to a system or device having a computer that can execute the program directly from a recording medium or via wired / wireless communication, and the program is executed. Therefore, the program code itself, supplied and installed on a computer to implement the functional processes described above, also embodies the present invention. In other words, the computer program itself for implementing the functional processes of the present invention is also included in the present invention. In this case, the program may take any form, such as object code, a program executed by an interpreter, or script data supplied to an OS, as long as it has the program's functionality. Recording media for providing the program may include, for example, a hard disk, a magnetic recording medium such as a magnetic tape, an optical / magneto-optical storage medium, or a non-volatile semiconductor memory. Another possible method for providing the program is to store the computer program forming the present invention on a server on a computer network, and then download the computer program to a connected client computer.

[0089] The disclosure of this embodiment includes the following configuration of an imaging device. (Configuration 1) an illumination unit that irradiates terahertz waves; an imaging unit that captures an image of a subject; a control unit that controls the illumination unit or the imaging unit in accordance with a positional relationship between a target area photographed by the imaging unit and the imaging unit, so that a positional relationship between the illumination unit that irradiates the target area and the imaging unit that photographs the target area satisfies a predetermined condition; An imaging system comprising: (Configuration 2) The lighting unit includes a plurality of lighting units at different positions, 2. The imaging system according to configuration 1, wherein the control unit causes the target area to be illuminated by one of the plurality of illumination units that is located at a position where the condition is satisfied. (Configuration 3) the plurality of illumination units include a first illumination unit whose distance to the imaging unit is a first distance and a second illumination unit whose distance to the imaging unit is longer than the first distance; the target area includes a first target area whose distance to the imaging unit is a second distance, and a second target area whose distance to the imaging unit is longer than the second distance; The imaging system of configuration 2, wherein the control unit causes the first illumination unit to irradiate terahertz waves when the target area is the first target area, and causes the second illumination unit to irradiate terahertz waves when the target area is the second target area. (Configuration 4) the target area includes a first target area and a second target area that is located at a longer distance to the imaging unit than the first target area; The imaging system of configuration 1 or 2, wherein the control unit is configured to cause the intensity of light emitted by the terahertz waves to be higher when the illumination unit irradiates the second target area with terahertz waves than when the illumination unit irradiates the first target area with terahertz waves. (Configuration 5) 5. The imaging system according to any one of configurations 2 to 4, wherein the plurality of illumination units and the imaging unit are provided along one direction. (Configuration 6) the plurality of illumination units include a first illumination unit and a second illumination unit, 6. The imaging system according to any one of configurations 2 to 5, wherein the second illumination unit is provided at a position different from a line passing through the first illumination unit and the imaging unit. (Configuration 7) each of the plurality of illumination units belongs to one of a plurality of groups divided according to a distance from the imaging unit to the illumination unit; The imaging system according to any one of configurations 2 to 6, wherein the control unit causes the illumination units belonging to a group among the plurality of groups that is located at a position where the condition is satisfied to irradiate terahertz waves. (Configuration 8) The imaging system according to any one of configurations 1 to 7, wherein, when the positional relationship between the target area and the imaging unit changes, the control unit controls the illumination unit or the imaging unit so that the condition is satisfied after the change. (Configuration 9) the illumination unit is one or more illumination units, The imaging system according to any one of configurations 1 to 8, wherein, when the positional relationship between at least one lighting unit and the imaging unit does not satisfy the condition, the control unit controls the specific lighting unit so that the positional relationship between a specific lighting unit that has not irradiated the target area and the imaging unit satisfies the condition.

[0090] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0091] 100: Imaging system 110: Control unit 120: Lighting Department 130: Imaging unit 140: Processing section 150: Display section 200: Object 210: Holding part

Claims

1. an illumination unit that irradiates terahertz waves; an imaging unit that captures an image of a subject; a control unit that controls the illumination unit or the imaging unit in accordance with a positional relationship between a target area photographed by the imaging unit and the imaging unit, so that a positional relationship between the illumination unit that irradiates the target area and the imaging unit that photographs the target area satisfies a predetermined condition; An imaging system comprising:

2. The lighting unit includes a plurality of lighting units at different positions, The imaging system according to claim 1 , wherein the control unit causes the target area to be illuminated by one of the plurality of illumination units that is located at a position where the condition is satisfied.

3. the plurality of illumination units include a first illumination unit whose distance to the image capture unit is a first distance and a second illumination unit whose distance to the image capture unit is longer than the first distance; the target area includes a first target area whose distance to the imaging unit is a second distance, and a second target area whose distance to the imaging unit is longer than the second distance; 3. The imaging system according to claim 2, wherein the control unit causes the first illumination unit to irradiate the target area with terahertz waves when the target area is the first target area, and causes the second illumination unit to irradiate the target area with terahertz waves when the target area is the second target area.

4. The target area includes a first target area and a second target area that is located at a longer distance to the imaging unit than the first target area, 2. The imaging system of claim 1, wherein the control unit controls the intensity of light emitted by the terahertz waves to be higher when the illumination unit irradiates the second target area with terahertz waves than when the illumination unit irradiates the first target area with terahertz waves.

5. The imaging system according to claim 2 , wherein the plurality of illumination units and the imaging unit are provided along one direction.

6. the plurality of illumination units include a first illumination unit and a second illumination unit, The imaging system according to claim 2 , wherein the second illumination unit is provided at a position different from a line passing through the first illumination unit and the imaging unit.

7. each of the plurality of illumination units belongs to one of a plurality of groups divided according to a distance from the imaging unit to the illumination unit; The imaging system according to claim 2 , wherein the control unit causes the illumination units belonging to a group among the plurality of groups that is located at a position where the condition is satisfied to emit terahertz waves.

8. The imaging system according to claim 1 , wherein, when the positional relationship between the target area and the imaging unit changes, the control unit controls the illumination unit or the imaging unit so that the condition is satisfied after the change.

9. the illumination unit is one or more illumination units, 2. The imaging system according to claim 1, wherein, when a positional relationship between at least one illumination unit and the imaging unit does not satisfy the condition, the control unit controls the specific illumination unit so that a positional relationship between a specific illumination unit that has not irradiated the target area and the imaging unit satisfies the condition.

10. A control method for an imaging system including an illumination unit that irradiates terahertz waves, an imaging unit that images a subject, and a control unit that controls the illumination unit or the imaging unit, A control method for an imaging system, comprising a step of controlling the illumination unit or the imaging unit, depending on the positional relationship between a target area to be photographed by the imaging unit and the imaging unit, so that the positional relationship between the illumination unit that illuminates the target area and the imaging unit that photographs the target area satisfies a predetermined condition.

11. A program for causing a computer to realize a function of controlling an illumination unit or an imaging unit that irradiates a target area with terahertz waves and that images the target area, depending on the positional relationship between the imaging unit and a target area that is imaged by the imaging unit that images a subject, so that the positional relationship between the illumination unit or the imaging unit that images the target area satisfies a predetermined condition.

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