CN116774497A - Lighting device and imaging system - Google Patents

Abstract

The invention relates to an illumination device and an imaging system, which aim to realize uniform illumination in a large illumination range. An illumination device for illuminating an imaging range of an imaging device is characterized by comprising at least two illumination units each having a plurality of light sources arranged in a predetermined direction and a light converging optical system extending in the arrangement direction of the plurality of light sources, wherein the light from the plurality of light sources is converged into a linear shape after passing through the light converging optical system, and the at least two illumination units are arranged so as to face each other with the arrangement direction of the plurality of light sources, the extending direction of the light converging optical system, and the converging direction of the light passing through the plurality of light sources and the light converging optical system forming angles with each other.

Description

Lighting device and imaging system

Technical Field

The present invention relates to an illumination device and an imaging system.

Background

Patent document 1 (JP 2007-225591) discloses a lighting device including a plurality of light sources arranged in a predetermined direction and a condenser lens extending in the direction of arrangement of the light sources, wherein light from each light source passes through the condenser lens and is condensed into a linear shape at a position separated from the condenser lens by a predetermined distance. The lighting device includes a diffusion lens provided in a path of light from each light source to a light collecting position, and diffuses the light mainly in an arrangement direction of the light sources.

Patent document 2 (JP 2016-051203 a) discloses an optical information reading apparatus, which is provided with a light projecting system that projects light from a light source onto a reading object through a light projecting lens; a light receiving system for imaging reflected light from the reading object on a light receiving surface of the image pickup element through a light receiving lens; and a signal processing system for receiving an output signal from the imaging element and reading information of the reading object. The light projection system projects light in a band-like range that is longer in a predetermined direction and shorter in a width direction substantially perpendicular to the longitudinal direction in a light projection plane substantially perpendicular to the optical axis of the light receiving lens. The incident surface of the light projection lens, on which light from the light source is incident, is formed in the same concave shape in the longitudinal direction and in the same convex shape in the width direction. The light incident on the incident surface is emitted toward the light projecting plane, and the light projecting lens has an emission surface that is a free-form surface capable of obtaining a predetermined light quantity distribution in the longitudinal direction of the light projecting plane.

However, from the standpoint of uniformly irradiating a large irradiation range (for example, a large light distribution angle and from a short distance to a long distance), there is still room for improvement in the conventional techniques including patent documents 1 and 2.

Disclosure of Invention

The present invention has been made in view of the above-described problems, and an object thereof is to provide an illumination device and an imaging system capable of uniformly irradiating a large irradiation range.

An aspect of the illumination device according to the present invention is an illumination device for illuminating an imaging range of an imaging device, including at least two illumination units each having a plurality of light sources arranged in a predetermined direction and a light converging optical system extending in the arrangement direction of the plurality of light sources, wherein light from the plurality of light sources is converged into a linear shape after passing through the light converging optical system, and the at least two illumination units are disposed outward from each other at angles of the arrangement direction of the plurality of light sources, the extension direction of the light converging optical system, and the convergence direction of light passing through the plurality of light sources and the light converging optical system.

In another aspect, the illumination device according to the present embodiment is an illumination device for illuminating an imaging range of an imaging device, comprising a light source and a condensing optical system for condensing light from the light source into a linear shape, and further comprising a positive cylindrical lens having a convex cylindrical surface and a negative cylindrical lens having a concave cylindrical surface

The invention provides an illumination device and an imaging system capable of uniformly illuminating a large illumination range.

Drawings

Fig. 1 is a schematic view of a moving object on which an illumination device and an imaging system according to the present embodiment are mounted.

Fig. 2 is a hardware configuration block diagram of the imaging system according to the present embodiment.

Fig. 3 is a schematic diagram of an irradiation range and an imaging range of the imaging system according to the present embodiment.

Fig. 4 is a second schematic view of the irradiation range and the imaging range of the imaging system according to the present embodiment.

Fig. 5 is a schematic view of a first conventional illumination optical system.

Fig. 6 is a schematic diagram of a second conventional illumination optical system.

Fig. 7 is a schematic view of a lighting device according to the first embodiment.

Fig. 8 is a schematic view of a lighting device according to a comparative example.

Fig. 9 is a schematic view of a lighting device according to a second embodiment.

Fig. 10 is a schematic view of a lighting device according to a comparative example.

Fig. 11 is a schematic view of a lighting device according to a third embodiment.

Fig. 12 is a schematic view of a lighting device according to a fourth embodiment.

Fig. 13 is a schematic view of a lighting device according to a fifth embodiment.

Fig. 14 is a schematic view of a lighting device according to a sixth embodiment.

Fig. 15 is a schematic view of a lighting device according to a seventh embodiment.

Detailed Description

The illumination device and the imaging system according to the present embodiment are described in detail below with reference to the drawings.

The illumination device and the imaging system according to the present embodiment are used, for example, when photographing and inspecting a wall surface of a structure such as a tunnel. When the wall surface of the tunnel is irradiated with a plurality of illumination devices, it is required that the illumination device monomers uniformly irradiate an irradiation range (for example, a large light distribution angle of 45 ° or more, a short distance to a long distance of 30cm to 10 m). In the present embodiment, since two illumination devices are used for illumination, a large illumination range can be realized with a small configuration without using a cylindrical lens for compensating spherical aberration for each illumination device. In addition, an imaging device for tunnel inspection uses a linear array sensor in combination with an area sensor other than a general digital camera, and an illumination device also uses linear array illumination. In other words, the imaging range of the imaging device and the illumination range of the illumination device are both linear.

< moving object carrying illumination device and imaging System >

Fig. 1 is a schematic diagram of an example of a mobile body in which the illumination device and the imaging system according to the present embodiment are mounted, in which (a) is a schematic diagram of a vehicle 500 as an example of the mobile body, as seen in a moving direction, and (B) is a schematic diagram of the vehicle 500 moving (traveling) inside a tunnel 600. The imaging system 100, in a state of being mounted on the vehicle 500, photographs the inner wall of a tunnel 600 as an example of an object.

In fig. 1 (a), the imaging system 100 is fixed to the roof of the vehicle 500. The portion of the vehicle in which the image pickup system 100 is mounted is not limited to the roof. The vehicle may be a front or rear hood, a cargo box, or the like. In the case of attaching the on-vehicle imaging system 100 to the roof, a hook member or the like may be used, similarly to a ski bracket or the like for a vehicle.

In fig. 1 (B), there is a lane 710 on the left side and a lane 720 on the right side with respect to the center of the road 700. The vehicle 500 moves on the lane 720 from inside to outside with respect to the drawing plane. In this example, a roadway 730 is provided on one side of the lane 710 (the lane opposite to the vehicle 500). Since the side of the lane 720 has no sidewalk, the vehicle 500 moves closer to the wall surface of the tunnel 600 on the side of the vehicle 500 than the sidewalk.

The broken line 100A of fig. 1 (B) represents the imaging range of the imaging system 100. That is, the imaging system 100 captures an area 600A (an area indicated by a bold line) within an imaging range indicated by a broken line 100A among the wall surfaces of the tunnel 600. As shown by the thick line, in the present embodiment, the boundary between the tunnel wall surface (earth covering portion) and the ground is imaged.

The image is captured by the imaging system 100 while the vehicle 500 is moving, and the right half wall surface of fig. 1 (B) is captured from the entrance to the exit of the tunnel 600. Then, while moving the vehicle 500 in the opposite direction on the lane 710 on the opposite side of the case of fig. 1 (B), the left half wall surface of fig. 1 (B) from the entrance to the exit of the tunnel 600 is photographed by the photographing system 100.

By stitching the image of the wall surface captured in the state of fig. 1 (B) with the image of the wall surface captured while moving the vehicle 500 in the opposite direction on the lane 710 on the opposite side to the case of fig. 1 (B), a captured image of the entire wall surface from the entrance to the exit of the tunnel 600 can be obtained. In order to stitch the images together to form a single unfolded image, the wall images are preferably taken with the top portions overlapping each other. In other words, when the wall surface of the tunnel 600 is photographed during the round trip, it is preferable to overlap the forward and backward imaging regions in a direction intersecting the traveling direction of the vehicle 500 so as to avoid the existence of an area that is not photographed on the wall surface of the tunnel 600.

The vehicle 500 is not limited to a vehicle that runs on a road, and may be a vehicle that runs on a railway, and may be a vehicle that is not powered, such as a dolly or a cart, or may be a vehicle that is not powered. The mobile body is not limited to a vehicle, and may be moved in the air like an unmanned aerial vehicle. Further, the tunnel is not limited to the traffic tunnel, and may be a tunnel such as a water guide.

The vehicle in this embodiment follows the rule of left-hand traffic. Thus, the image pickup device is arranged to pick up the left side in the traveling direction. For countries and situations where the right side passes, the image pickup device may be provided in such a manner that the right side of the traveling direction is photographed. At this time, it is necessary to mount a camera unit (imaging device) 300 and an illumination unit (illumination device) 400, which will be described later, on the vehicle after rotating 180 degrees.

Fig. 2 is a block diagram showing an example of a hardware configuration of the imaging system 100 according to the present embodiment. The imaging system 100 includes an imaging unit 300, an illumination unit 400, imaging control units 110, TOF (Time of Flight) sensors 141, IMU (Inertial Measurement Unit) 160, and a speedometer/motion distance meter 170.

Although only one imaging unit 300 is illustrated in fig. 2, a plurality of (for example, five) imaging units 300 may be mounted in the imaging system 100. Although only one illumination unit 400 (one illumination unit 400 is depicted with respect to one imaging unit 300) is depicted in fig. 2, two illumination units 400 may be provided with respect to one imaging unit 300 as in one embodiment described later. For example, two illumination units 400 are provided separately on both sides of the image pickup unit 300 located in the middle. It is also possible to provide a plurality of sets (e.g., five sets) of such image pickup units 300 with two illumination units 400 on both sides.

As shown in fig. 1, the imaging unit 300 images the wall surface inside the tunnel, and the illumination unit 400 irradiates light to the wall surface inside the tunnel in order to allow the imaging unit 300 to image.

The TOF sensor 141 measures the distance from the wall of the tunnel 600 to the TOF sensor 141. Specifically, the TOF sensor 141 irradiates the wall surface of the tunnel 600, and measures the distance to the wall surface of the tunnel 600 based on the time when the reflected light is received. If the light receiving element is the TOF sensor 141 using the area sensor, a two-dimensional contour image of the display color corresponding to the distance can be obtained. The IMU160 may measure three-axis angle/angular velocity and acceleration that control the motion of the vehicle 500, and the speedometer/range gauge 170 may measure the speed/range of the vehicle 500. The data measured by the IMU160 and the speedometer/motion distance meter 170 are outputted to the HDD114 through the imaging control section 110 and stored for later geometric compensation of the size, inclination, and the like of the wall image through image processing.

The imaging unit 300 is an example of an imaging section (imaging device), and includes a lens 331-1 and a line CCD331-2. The line CCD331-2 is a CCD in which pixels are arranged in a linear (linear shape), and the image pickup unit 300 is fixed to the vehicle 500 in such a manner that the pixel arrangement direction of the line CCD331-2 intersects with the moving direction of the vehicle 500. The lens 331-1 forms an object image located in the optical axis direction of the lens 331-1 on the image pickup surface of the line CCD331-2. The line CCD331-2 captures an image of the imaged subject. The lens 331-1 is an example of an "imaging optical system". An aperture 331-1a is provided inside the lens 331-1. The diaphragm 331-1a is an iris diaphragm having diaphragm blades, and is an opening of variable diameter. The diameter of the opening can be changed by connecting a driving source such as a motor to the diaphragm blades and driving the motor in accordance with a control signal. In this way, the light quantity of the light passing through the lens 331-1 can be changed, thereby changing the brightness of the subject image imaged through the lens 331-1.

The illumination unit 400 is an example of an illumination unit (illumination device) and includes a lens 431-1 and a light source 431-2. The light source 431-2 may irradiate the subject located in the optical axis direction of the lens 431-1 through the lens 431-1 using a metal halide lamp, LED (Light Emitting Diode), or the like. An aperture 431-1a is provided in the lens 431-1. The diaphragm 431-1a is an opening of variable diameter, and by changing the diameter of the opening, the light amount (brightness) of illumination light irradiated via the diaphragm 431-1 can be changed. The aperture 431-1a of the lens 431-1 may be omitted, and the light amount adjustment may be performed by adjusting the output of the LED of the light source 431-2.

The illumination unit 400 is described as having one light source 431-2 in fig. 2, but as in one embodiment described later, the illumination unit 400 may have a plurality of light sources arranged in a prescribed direction. The direction in which the plurality of light sources are arranged in the predetermined direction corresponds to the "arrangement direction". The "arrangement direction" may be exchanged with (may be synonymous with) the "arrangement direction".

The imaging control section 110 has a CPU (Central Processing Unit ) 111, a ROM (Read Only Memory) 112, a RAM (Random Access Memory ) 113, an HDD (Hard Disk Drive) 114, an external I/F (interface) 115, and a buzzer 116, which are electrically connected to each other through a system bus 117.

The ROM112 stores various programs and data, various setting information, and the like, and the RAM113 temporarily stores programs and data. The CPU111 reads programs, data, setting information, and the like from the ROM112 and the like onto the RAM113, executes processing, and realizes control of the entire imaging system 100 and processing of image data. Here, the processing of the image data is, for example, processing of stitching the line images captured by the plurality of imaging units 300, processing of stitching the line images captured continuously by the plurality of imaging units 300 at predetermined time intervals while moving the vehicle along the vehicle moving direction, or the like. The CPU111 can also realize various functions.

The control, image processing, and some or all of the various functions performed by the CPU111 may be implemented by an FPGA (Field-Programmable Gate Array, programmable array logic) or an ASIC (Application Specific Integrated Circuit ).

The HDD114 stores image data input from the image capturing unit 300, sensor data input from the TOF sensor 141, IMU160, and speedometer/motion distance meter 170, and the like. The external I/F115 realizes a function of a user interface for a user to operate the image pickup system 100, and a function of an interface for exchanging data or signals between the image pickup system 100 and an external device such as a PC (Personal Computer ). The buzzer 116 sounds a beep, gives a warning notice to the user, or the like.

Fig. 3 and 4 are one or two schematic views of the irradiation range and the imaging range of the imaging system 100 according to the present embodiment. As shown in fig. 3, two illumination units 300A, 400B are separated from each other, respectively provided on both sides of the camera unit 400 located in the middle, and are provided to face each other at an angle to each other. That is, the illumination unit 400A located above in fig. 3 is arranged to rotate clockwise from the left facing direction Fang Shao, and the illumination unit 400B located below in fig. 3 is arranged to rotate slightly counterclockwise from the left facing direction.

As shown in fig. 3 and 4, the illumination unit 400A irradiates the wall surface (region 600A) of the tunnel 600 as the subject with illumination light having a rectangular illumination range LA having a longitudinal direction as a longitudinal direction, with the front direction being the illumination direction (left direction in fig. 3). The illumination unit 400B irradiates the wall surface (region 600A) of the tunnel 600 as the object with illumination light in a rectangular illumination range LB having a longitudinal direction as a longitudinal direction, with illumination light in the front direction (left direction in fig. 3) as the illumination direction. A portion of the illumination range LA of the illumination unit 400A below and a portion of the illumination range LB of the illumination unit 400B above overlap each other.

As shown in fig. 3 and 4, the imaging unit 300 has a linear imaging range P having a longitudinal direction as a longitudinal direction among the irradiation ranges LA and LB of the illumination units 400A and 400B. Accordingly, the imaging unit 300 can capture an image of the wall surface (region 600A) of the tunnel 600 as the subject irradiated with the irradiation light of the illumination units 400A, 400B. The imaging range P is a range of the array direction of the plurality of pixels of the line CCD331-2 provided in the imaging unit 300. As described above, the imaging system 100 according to the present embodiment can capture an image of the wall surface (region 600A) of the tunnel 600, which is an object, by using the irradiation light irradiated from the two illumination units 400A and 400B.

< background and summary of the invention >

As social infrastructure becomes decayed, maintenance and management become more and more important, and efficiency improvement and security of tunnel inspection become important issues. Although there is a technique of installing a powerful lighting device and a line camera with a high shutter speed on a vehicle and photographing the inner wall surface of a tunnel while traveling, a large vehicle capable of being equipped with a battery and a device is generally used. In view of this, it is necessary to consider a tunnel monitoring system that uses a camera with an extended depth of field and a linear array illumination device that efficiently illuminates only a photographing region, suppresses the number of devices, and has a compact system configuration, so that a common vehicle can be mounted. Thus, the ordinary vehicle can be used for shooting the image of the wall surface of the tunnel while running.

In order to achieve miniaturization of the lighting device, the conventional tunnel monitoring system uses only one high-output single-color LED for one lighting unit, and only a single-color image is captured. The photographed picture cannot be an image similar to the actual appearance, and there is a problem that rust or water leakage cannot be detected, and the color of the chalk is difficult to judge. If the light source is replaced by a white LED, the output power is insufficient, and the tunnel wall surface cannot be shot.

In addition, in the technical solution disclosed in patent document 1, since the linear array illumination having a length equivalent to the linear array length in which the LEDs are arranged is illuminated directly downward, the actual light distribution angle is very small and is mainly used for short-distance inspection (only suitable for short-distance inspection). On the other hand, the tunnel monitoring system needs to photograph the wall surfaces of tunnels of various sizes, and needs to irradiate the wall surfaces far from the lighting device, and the required length is several meters, so that a large light distribution angle is required.

Although the light distribution angle is large in patent document 2, for example, there are a maximum of two usable LEDs, and therefore, there are problems that the number is insufficient and the cost performance is poor due to the use of a free-form lens.

In contrast, the main purpose of the illumination device and the imaging system of the present embodiment is to uniformly irradiate a large irradiation range (for example, a large light distribution angle, and an application range includes a short distance to a long distance). Another object of the illumination device and the imaging system of the present embodiment is to capture a color image of a tunnel wall surface with, for example, a tunnel monitoring system mounted on a general vehicle.

In order to achieve the above object, the illumination device and the imaging system according to the present embodiment are linear array illumination devices in which a plurality of LEDs are arranged, and are capable of efficiently illuminating an imaging region as wide-angle linear array illumination using a plurality of LEDs, and further, a plurality of illumination optical systems in which LEDs are arranged in the longitudinal direction are provided so as to form angles with each other, so that illumination light overlaps each other at the imaging region, thereby realizing linear array illumination with a large light distribution angle.

< existing illumination optical System >

Fig. 5 is a schematic diagram of a first conventional illumination optical system. As shown in fig. 5, the conventional illumination optical system has a special LED light source, a lens, a cylindrical lens having negative diopter in a single direction, and a cylindrical lens having positive diopter in a single direction. In fig. 5, (a) has a positive cylindrical lens, and (B) has a negative cylindrical lens. The cylindrical lens having a positive diopter in a single direction has a function of converging light in the width direction of the linear array, and the cylindrical lens having a negative diopter in a single direction has a function of compensating spherical aberration in the length direction of the linear array. When the linear array is used for illumination, the width direction of the linear array is parallel light, and the length direction is diffuse light, so that the positive cylindrical lens only applies energy to the width direction, but not to the length direction. In the case of such linear array illumination with a large light distribution angle, at least positive and negative cylindrical lenses need to be used as in the first embodiment described later.

Fig. 6 is a schematic diagram of a second example of a prior art illumination optical system. For example, for colorization of a tunnel monitoring system, high-brightness white linear array illumination is required, and a single light source cannot ensure sufficient brightness required for photographing, so that a plurality of LED light sources are used. When LEDs are arranged in a single direction in order to increase the output of illumination light, it is conceivable to arrange the LEDs in the width direction or the length direction of the array. However, when LEDs are arranged in the width direction of the linear array, the diameter of the cylindrical lens converging in the width direction becomes a bottleneck, whereas when LEDs are arranged in the length direction of the linear array, the diameter of the cylindrical lens compensating for spherical aberration in the length direction becomes a bottleneck, and it is difficult to avoid enlargement. Fig. 6 illustrates that LEDs are arranged in a longitudinal direction of the linear array, and when LEDs are arranged in a width direction of the linear array, the arrangement of each cylindrical lens diameter also leads to an increase in size of the device. In contrast, since the illumination device and the imaging system according to the present embodiment are applied to a tunnel monitoring system that can be mounted on a general vehicle, downsizing is an important issue.

< first embodiment >

Fig. 7 is a schematic view of the illumination device according to the first embodiment, wherein (a) is a perspective view of the illumination device, (B) is an illuminance distribution of linear illumination light on a short-distance projection surface, and (C) is an illuminance distribution of linear illumination light on a long-distance projection surface. (B) The distance from the short-distance projection surface of (C) to the long-distance projection surface is 1m, the distance from the short-distance projection surface to the long-distance projection surface is 8m, and the distance may be, for example, 30cm to 10m.

The lighting device of the first embodiment has a light source (LED) 410 and a condensing optical system 420 that condenses light of the light source 410 into a linear shape. The condensing optical system 420 has a positive lens 421, a positive lens 422, a negative cylindrical lens 423, and a positive cylindrical lens 424.

The two positive lenses 421 and 422 in fig. 7A are lenses provided in the front stages of the negative cylindrical lens 423 and the positive cylindrical lens 424, but the number and positive and negative types of lenses have a certain degree of freedom, and various design modifications can be made. For example, the lens may be a single positive lens or a single negative lens, may be a single positive and negative lens, or may be three or more lenses composed of a combination of positive and negative lenses.

The negative cylindrical lens 423 has a concave cylindrical surface 423A and the positive cylindrical lens 424 has a convex cylindrical surface 424A. The axis of the concave cylindrical surface 423A of the negative cylindrical lens 423 and the axis of the convex cylindrical surface 424A of the positive cylindrical lens 424 correspond to the length direction and the width direction of the linear converging surface, respectively, and are mutually orthogonal to each other. In the example of fig. 7 (a), the axis of the convex cylindrical surface 424A of the positive cylindrical lens 424 corresponds to the length direction of the strip-shaped condensing surface, and the axis of the concave cylindrical surface 423A of the negative cylindrical lens 423 corresponds to the width direction of the strip-shaped condensing surface, but the relationship may be reversed.

The concave cylindrical surface 423A of the negative cylindrical lens 423 faces the light source 410 side, the convex cylindrical surface 424A of the positive cylindrical lens 424 faces the linear converging surface side, and the planar portion of the negative cylindrical lens 423 where the concave cylindrical surface 423A is not formed and the planar portion of the positive cylindrical lens 424 where the convex cylindrical surface 424A is not formed are disposed back-to-back. This can improve the space efficiency of the condensing optical system 420 and the lighting device, and can reduce the size.

The order of arrangement of the negative cylindrical lenses 423 and the positive cylindrical lenses 424 may be interchanged, and there is also a degree of freedom on the surface on which one of the concave cylindrical surfaces 423A and the convex cylindrical surfaces 424A are formed. For example, the concave cylindrical surface 423A of the negative cylindrical lens 423 is formed to face the linear condensing surface side, and the convex cylindrical surface 424A of the positive cylindrical lens 424 is formed to face the light source 410 side.

As shown in fig. 7 (B) and (C), by compensating spherical aberration using the cylindrical lens 423 having negative diopter in the length direction, a light beam having a large angle with the depth direction can also be emitted as parallel light. At this time, linear array illumination with uniform illuminance distribution can be achieved regardless of the distance of the projection surface.

Fig. 8 is a schematic view of a lighting device according to a comparative example. This comparative example omits the negative cylindrical lens 423 in the lighting device of the first embodiment shown in fig. 7, and instead, a parallel planar plate 425 having no diopter is provided. If the negative cylindrical lens 423 for compensating the longitudinal spherical aberration is not used, parallel light rays can be emitted in a range of a light distribution angle of about 20 °, but an angle equal to or larger than this becomes converged light due to the influence of the spherical aberration. The tunnel monitoring system needs to have a light distribution angle of 45 °, and thus a negative cylindrical lens 423 as in the first embodiment is required. When the positive cylindrical lens 424 is mounted without the negative cylindrical lens 423 being mounted, the light beam having a large angle with the depth direction becomes converging light due to spherical aberration caused by an optical path difference to the positive cylindrical lens 424 when the light beam having been emitted in parallel with the depth direction is emitted as parallel light. Therefore, the intensity varies with the distance of the projection surface, and uniform linear illumination cannot be obtained.

< second embodiment >

Fig. 9 is a schematic view of an illumination device according to a second embodiment, wherein (a) and (B) are schematic views of the illumination device, (C) is an illuminance distribution diagram of a short-distance projection surface of linear illumination light, and (D) is an illuminance distribution diagram of a long-distance projection surface of linear illumination light. (C) The short-distance projection surface of (D) is 1m, and the long-distance projection surface of (D) is 8m, but the range from the short-distance projection surface to the long-distance projection surface is, for example, 30cm to 10m.

Fig. 9 includes a (a) view of the plurality of light sources 430A/430B and the condensing optical system 440A/440B of the two illumination units 400A/400B seen from a direction perpendicular to the arrangement direction of the plurality of light sources 430A/430B and a (B) view seen from the arrangement direction of the plurality of light sources 430A/430B.

The lighting device according to the second embodiment combines two lighting units 400A and 400B to form a configuration in which the light distribution angle is 50 °, and thus the light distribution angle of one lighting unit is 25 °. As described above, the configuration of the cylindrical lens 423 having negative refractive power in the longitudinal direction for compensating spherical aberration as shown in the first embodiment (fig. 7 (a)) can be made such that the bottleneck in the case of arranging LEDs in the longitudinal direction is not used, and the LEDs can be arranged in the longitudinal direction. When a plurality of (for example, five) camera units (image pickup apparatuses) 300 are provided, the illumination units 400A,400B are provided corresponding to the number of the image pickup units 300, and thus the illumination units 400A,400B may be two or more groups (at least two illumination units may be provided).

The illumination unit 400A has a plurality of light sources 430A arranged in a predetermined direction and a condensing optical system 440A extending in the arrangement direction of the plurality of light sources 430A, and light of the plurality of light sources 430A is condensed into a linear shape by the condensing optical system 440A. The condensing optical system 440A includes a positive lens 441A, a positive lens 442A, and a positive lens 443A. In fig. 9 (a) and (B), the positive lens 441A, the positive lens 442A, and the positive lens 443A are plano-convex lenses, respectively, but both side surfaces may have curvatures. The light collecting optical system 440A may have a single, two or four or more lenses.

The illumination unit 400B includes a plurality of light sources 430B arranged in a predetermined direction and a light condensing optical system 440B extending in the arrangement direction of the plurality of light sources 430B, and light from the plurality of light sources 430B is condensed into a linear shape by the light condensing optical system 440B. The condensing optical system 440B includes a positive lens 441B, a positive lens 442B, and a positive lens 443B. In fig. 9 (a) and (B), the positive lens 441B, the positive lens 442B, and the positive lens 443B are each plano-convex lenses, but both side surfaces may have curvature. The light collecting optical system 440B may have a single, two, or four or more lenses.

The condensing optical systems 440A,440B of the two illumination units 400A,400B include cylindrical lenses having no diopter with respect to the arrangement direction of the plurality of light sources 430A,430B and having a positive diopter with respect to the direction perpendicular to the arrangement direction of the plurality of light sources 430A, 430B. That is, the condensing optical systems 440A,440B of the two illumination units 400A,400B respectively include cylindrical lenses having no diopter with respect to the arrangement direction of the plurality of light sources 430A,430B and having a positive diopter with respect to the direction perpendicular to the arrangement direction of the plurality of light sources 430A, 430B. In fig. 9 (a) and (B), the positive lenses 441A/441B, 442A/442B, 443A/443B constituting the two illumination units 400A/400B may be cylindrical lenses that are lenses having no diopter with respect to the arrangement direction of the plurality of light sources 430A/430B, but having a positive diopter with respect to the direction perpendicular to the arrangement direction of the plurality of light sources 430A/430B.

In the illumination device of the second embodiment, the two illumination units 400A,400B are disposed so that the arrangement direction of the plurality of light sources 430A,430B, the extending direction of the condensing optical system 440A,440B, and the converging direction of the light of the plurality of light sources 430A,430B and the condensing optical system 440A,440B are angled outward from each other. Thus, a large irradiation range (for example, a light distribution angle of 45 DEG or more, a short distance of 30cm to 10m, or a long distance) can be uniformly irradiated. The two illumination units 400A and 400B are arranged in a positional relationship in which the stripe-shaped illuminance distributions of the illumination units of the projection surface are combined with each other.

In the illumination device of the second embodiment, the two illumination units 400A,400B are disposed so as to form an angle with each other, and overlap on the projection surface so that the light distribution angle is about twice. In this case, the illuminance distribution on the short-distance projection surface is different from the illuminance distribution on the long-distance projection surface due to spherical aberration. For overlapping portions of the illumination distribution, the close-range projection plane may be adjusted from the distance and angle between the cells, and the far-range projection plane may be adjusted from the angle between the cells. At this time, the angle formed between the normals of the illumination units is about 25 °, the viewing angle is measured with reference to the midpoint between the centers of the Light Sources (LEDs) arranged on the illumination units, and the short-distance projection plane is 50 ° or more of the full angle, but a linear illuminance distribution with poor uniformity is formed. The long-distance projection surface is a uniform strip-shaped illumination distribution with a full angle of more than 50 degrees. In fig. 9 (C) and (D), the illuminance distribution of each of the two illumination units 400A and 400B is indicated by a broken line, and the resultant illuminance distribution of the two illumination units 400A and 400B is indicated by a solid line.

Fig. 10 is a schematic view of a lighting device of a comparative example. The comparative example is provided with the illumination unit 400X of one of the illumination units 400A,400B of the second embodiment shown in fig. 9 without angles. Fig. 10 includes (a) a diagram of the light-condensing optical system 440 of the plurality of light sources 400 and the illumination unit 440X seen from a direction perpendicular to the arrangement direction of the plurality of light sources 430, and (B) a diagram seen from the arrangement direction of the plurality of light sources 430. The illumination unit 400X of the comparative example also has a lens configuration in which a plurality of light sources 430 are arranged to achieve miniaturization. As described above, it is conceivable that a cylindrical lens that compensates for spherical aberration in the longitudinal direction is not used as a configuration that causes light sources (e.g., LEDs) to be more closely arranged. In this configuration, since LEDs can be arranged along the length of the LED substrate, not only the device can be miniaturized, but also a plurality of LEDs can be provided.

However, the comparative example shown in fig. 10 has a disadvantage in that since spherical aberration is not compensated, illuminance distribution varies with distance of the projection surface, and a wide angle cannot be achieved. At this time, if the viewing angle is measured from the center of the arranged LEDs, the linear illuminance distribution range has a full angle of about 45 ° at the short-distance projection surface and a full angle of about 25 ° at the long-distance projection surface. In this way, when a cylindrical lens for compensating spherical aberration is not used for downsizing, the light distribution angle of the illumination optical system becomes small.

< third embodiment >

Fig. 11 is a schematic view of a lighting device of a third embodiment. Here, (a) and (B) are schematic diagrams of the configuration of the illumination device, (C) is an illuminance distribution diagram of a short-distance projection surface of the linear illumination light, and (D) is an illuminance distribution diagram of a long-distance projection surface of the linear illumination light. (C) The short-distance projection surface of (D) is 1m, and the long-distance projection surface of (D) is 8m, but the range from the short-distance projection surface to the long-distance projection surface may be, for example, 30cm to 10m.

Fig. 11 includes a (a) view of the plurality of light sources 430A/430B and the condensing optical system 440A/440B of the two illumination units 400A/400B seen from a direction perpendicular to the arrangement direction of the plurality of light sources 430A/430B and a (B) view of the plurality of light sources 430A/430B and the condensing optical system 440A/440B of the two illumination units 400A/400B seen from the arrangement direction of the plurality of light sources 430A/430B.

In the second embodiment shown in fig. 9, since the distance (longitudinal pitch) between the illumination units 400A and 400B is too small, the illuminance distribution on the short-distance projection surface becomes too strong due to the large number of overlapping portions. Therefore, the third embodiment adjusts the illuminance distribution of the short-distance projection surface by increasing the distance (longitudinal pitch) between the illumination units 400A,400B and adjusting the overlapping portion of the short-distance projection surface. Thus, linear illumination with uniform illuminance distribution on the projection surface can be realized from a short distance to a long distance. The angle formed between the normals of the lighting units 400A,400B is about 25 °, and the distance (longitudinal pitch) between the lighting units 400A,400B is about 450mm. When the viewing angle is measured with reference to the midpoint between the centers of the Light Sources (LEDs) 430A, 440B arranged in the illumination units 400A,400B, both the short-distance projection surface and the long-distance projection surface are uniformly stripe-shaped illuminance distribution having a full angle of 50 ° or more.

< fourth embodiment >

Fig. 12 is a schematic view of an illumination device according to a fourth embodiment, in which (a) and (B) are schematic views of the configuration of the illumination device, (C) is an illuminance distribution diagram of a short-distance projection surface of linear illumination light, (D) is an illuminance distribution diagram of a long-distance projection surface of linear illumination light, and (E) a display reflector limits a divergence angle of a light source. (C) The short-distance projection surface of (D) is 1m, and the long-distance projection surface of (D) is 8m, but the range from the short-distance projection surface to the long-distance projection surface may be, for example, 30cm to 10m.

Fig. 12 includes (a) a diagram of the condensing optical system 430 of the plurality of light sources 400 and the illumination unit 440 seen from a direction perpendicular to the arrangement direction of the plurality of light sources 430 and (B) a diagram of the condensing optical system 430 of the plurality of light sources 400 and the illumination unit 440 seen from the arrangement direction of the plurality of light sources 430.

In the lighting device of the fourth embodiment, the plurality of light sources 430 are provided with reflectors 450 for limiting the divergence angle of each light source 430, so as to improve the brightness. The higher the brightness of the linear illumination in the tunnel monitoring system, the more a large tunnel can be photographed. In the fourth embodiment, in order to efficiently collect light scattered from the LED in all directions into linear array illumination, the divergence angle of the LED is reduced using the reflector 450, and more light is collected into linear array illumination. At this time, when the viewing angle is measured from the center of the arranged LEDs, the full angle of the stripe-shaped illuminance distribution range at the short-distance projection surface is about 45 °, and the full angle at the long-distance projection surface is about 25 °.

< fifth embodiment >

Fig. 13 is a schematic view of an illumination device according to a fifth embodiment, in which (a) is a schematic view of an illumination device configuration, (B) is an illuminance distribution diagram of a short-distance projection surface of linear illumination light, and (C) is an illuminance distribution diagram of a long-distance projection surface of linear illumination light. (B) The short-distance projection surface of (C) is 1m, and the long-distance projection surface of (C) is 8m, but the range from the short-distance projection surface to the long-distance projection surface may be, for example, 30cm to 10m.

Fig. 13 (a) is a schematic view of the light condensing optical system 440A/440B of the plurality of light sources 430A/430B and the two illumination units 400A/400B as seen from the arrangement direction of the plurality of light sources 430A/430B.

In the lighting device of the fifth embodiment, reflectors 450A,450B are provided for the plurality of light sources 430A,430B of the lighting device of the second embodiment, respectively. The two illumination units (400A, 400B) are disposed so as to form an angle with each other, and the light distribution angle is approximately doubled by overlapping the projection surfaces. At this time, the angle formed between the normals of the two illumination units 400A,400B is 25 °, and is a uniform bar-shaped illuminance distribution in which the full angle of the short-distance projection surface is 60 ° or more and the full angle of the long-distance projection surface is 50 ° or more when the viewing angle is measured with reference to the midpoint between the centers of the LEDs arranged in the illumination units.

< sixth embodiment >

Fig. 14 is a schematic view of an illumination device according to a sixth embodiment, in which (a) is a schematic view of the configuration of the illumination device, (B) is an illuminance distribution diagram of a short-distance projection surface of linear illumination light, and (C) is an illuminance distribution diagram of a long-distance projection surface of linear illumination light. (B) The short-distance projection surface of (C) is 1m, and the long-distance projection surface of (C) is 8m, but the range from the short-distance projection surface to the long-distance projection surface may be, for example, 30cm to 10m.

Fig. 14 (a) is a schematic view of the light condensing optical system 440A/440B of the plurality of light sources 430A/430B and the two illumination units 400A/400B as seen from the arrangement direction of the plurality of light sources 430A/430B.

In the lighting device of the sixth embodiment, reflectors 450A and 450B are provided for the plurality of light sources 430A and 430B in the lighting device of the third embodiment, respectively. The sixth embodiment can reduce overlapping of the short-distance projection surfaces by ensuring a large distance (longitudinal pitch) between the two illumination units 400A, 400B. In this case, even linear illumination can be realized regardless of the short distance or long distance, and thus linear illumination for uniformly illuminating tunnel walls of various sizes can be obtained. The angle formed between the normals of the two lighting units 400A,400B is 25 °, and the distance (longitudinal pitch) of the two lighting units 400A,400B is about 110mm. When the viewing angle is measured with reference to the midpoint between the centers of the LEDs arranged in the illumination unit, the full angle of both the close-range projection surface and the long-range projection surface is a uniform linear-array illuminance distribution of 50 ° or more.

< seventh embodiment >

Fig. 15 is a schematic view of an illumination device according to a seventh embodiment, in which (a) is a schematic view of an illumination device configuration, (B) is an illuminance distribution diagram of a short-distance projection surface of linear illumination light, and (C) is an illuminance distribution diagram of a long-distance projection surface of linear illumination light. (B) The short-distance projection surface of (C) is 1m, and the long-distance projection surface of (C) is 8m, but the range from the short-distance projection surface to the long-distance projection surface may be, for example, 30cm to 10m.

Fig. 15 (a) is a schematic view of the light condensing optical system 440A/440B of the plurality of light sources 430A/430B and the two illumination units 400A/400B as seen from the arrangement direction of the plurality of light sources 430A/430B.

In the seventh embodiment, two illumination units 400A,400B are provided separately on both sides of the image pickup unit 300. In other words, the present embodiment sets the image pickup unit 300 using the space between the two illumination units 400A,400B that are provided with a distance (longitudinal pitch) secured as in the sixth embodiment. In the seventh embodiment, the illumination optical systems are symmetrically arranged above and below (or in the front-rear direction and the left-right direction) the imaging unit 300, and therefore, the imaging unit 300 can perform appropriate imaging in agreement with the optical axis of the line illumination. At this time, the photographing angle of view of the line camera is 45 ° full angle, and the illumination unit illuminates a uniform line array having a full angle of 50 ° or more on both the near projection plane and the far projection plane with respect to the entrance pupil of the camera. Therefore, the imaging range of the camera can be irradiated over a wide range from a short distance to a long distance.

Description of the reference numerals

100. Image pickup system

300. Imaging unit (imaging device)

400 400A,400B lighting units (Lighting devices)

410. Light source (LED)

420. Condensing optical system

423. Negative cylindrical lens

423A concave cylinder

424. Positive cylindrical lens

424A convex cylinder

430A,430B light sources

440A,440B concentrating optical system

450 450A,450B mirrors

500. Vehicle (moving body)

600. Tunnel

700. Road

Claims (11)

1. An illumination device for illuminating an imaging range of an imaging device, characterized in that,

there are at least two lighting units,

the at least two illumination units each have a plurality of light sources arranged in a predetermined direction and a condensing optical system extending in the arrangement direction of the plurality of light sources,

the light of the plurality of light sources is converged into a linear shape after passing through the condensing optical system,

the at least two illumination units are disposed in such a manner that an arrangement direction of the plurality of light sources, an extending direction of the condensing optical system, and a converging direction of light passing through the plurality of light sources and the condensing optical system each form an angle with each other to face outward from each other.

2. A lighting device as recited in claim 1, wherein said at least two lighting units are disposed apart from each other so as to sandwich said image pickup device.

3. A lighting device as recited in claim 1 or claim 2, wherein said at least two lighting units are arranged in a positional relationship which allows for mutually combining linear illuminance distributions of each lighting unit on a projection surface.

4. A lighting device as recited in any one of claims 1-3, wherein said light collecting optical system comprises a cylindrical lens and has no diopter in a direction of arrangement of said plurality of light sources and has a positive diopter in a direction perpendicular to said direction of arrangement of said plurality of light sources.

5. A lighting device as recited in any one of claims 1-4, wherein a reflector is provided in said plurality of light sources for limiting a divergence angle of each light source.

6. An imaging system having an imaging device and an illumination device for illuminating an imaging range of the imaging device, characterized in that,

the lighting device has at least two lighting units,

the at least two illumination units each have a plurality of light sources arranged in a predetermined direction and a condensing optical system extending in the arrangement direction of the plurality of light sources,

the light of the plurality of light sources is condensed into a linear shape by the condensing optical system,

the at least two illumination units are disposed in such a manner that an arrangement direction of the plurality of light sources, an extending direction of the condensing optical system, and a converging direction of light passing through the plurality of light sources and the condensing optical system each form an angle with each other to face outward from each other.

7. The image capturing system according to claim 6, wherein the at least two illumination units are arranged apart from each other so as to sandwich the image capturing apparatus.

8. An illumination device for illuminating an imaging range of an imaging device, characterized by comprising a light source and a condensing optical system for condensing light from the light source into a linear shape, and further comprising a positive cylindrical lens having a convex cylindrical surface and a negative cylindrical lens having a concave cylindrical surface.

9. A lighting device as recited in claim 8, wherein an axis of said convex cylindrical surface of said positive cylindrical lens and an axis of said concave cylindrical surface of said negative cylindrical lens respectively correspond to a length direction and a width direction of said linear-shaped collecting surface, and are mutually orthogonal.

10. A lighting device as recited in claim 8 or claim 9, wherein said convex cylindrical surface of said positive cylindrical lens is oriented toward said linear collection surface and said concave cylindrical surface of said negative cylindrical lens is oriented toward said light source.

11. An image pickup system having an image pickup device and an illumination device that irradiates an image pickup range of the image pickup device, characterized by having a light source and a condensing optical system that condenses light of the light source into a linear shape, and further having a positive cylindrical lens having a convex cylindrical surface and a negative cylindrical lens having a concave cylindrical surface.