Imaging System

Abstract

To prevent deterioration of accuracy of an image analysis while imaging a subject from a plurality of directions.SOLUTION: An imaging system is provided so as to photograph a rope 1 along a running passage of the rope 1 from a different direction, and comprises: first and second cameras 11 and 21 that respectively include an image sensor outputting image data on a moving rope 1; first and second counter illumination devices 13 and 23 that are provided facing respective cameras 11 and 21 across the rope 1, and irradiate light toward respective cameras 11 and 21; and a synchronization signal circuit 40 that controls respective actions of the cameras 11 and 21, and the counter illumination devices 13 and 23. The synchronization signal circuit 40 is configured to control such that the first camera 11 of the pair, and the first counter illumination device 13 thereof, and the second camera 21 of the pair and the second counter illumination device 23 thereof are driven at the same timing, and a pair of the first camera 11 and the first counter illumination device 13 and a pair of the second camera 21 and the second counter illumination device 23 are driven respectively at a different timing.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an imaging system. [Background technology]

[0002] Patent Document 1 discloses a wire rope inspection device that uses a camera to capture an image of a wire rope and calculates the diameter of the wire rope using the image obtained by capturing the image. A conversion coefficient (actual dimension per pixel) between the number of pixels in the width of the image area of ​​the wire rope captured by the camera and the actual dimension of the wire rope width is set, and the actual dimension of the wire rope width is calculated from the image of the wire rope using this conversion coefficient. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2013 / 145823 publication

[0004] By placing the camera and light source facing each other across the wire rope, the camera captures the shadow created when the light emitted from the light source is blocked by the wire rope. A stable (clear) outline of the wire rope is captured, allowing image analysis to be performed with high precision, and for example, the diameter of the wire rope can be calculated with high precision from the image.

[0005] From the viewpoint of quality assurance, it is preferable to image the wire rope from multiple directions and perform image analysis of the wire rope using the images of the wire rope imaged from multiple directions. However, when two or more pairs of cameras and light sources arranged opposite to each other are provided, the contours of the acquired wire rope image may become unclear (blurred) compared to a wire rope image acquired when only one pair of cameras and light sources is provided using light from a light source that does not face the wire rope. If the contours are unclear, the accuracy of the image analysis may deteriorate. Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to enable imaging of a subject from multiple directions without deteriorating the accuracy of image analysis. [Means for solving the problem]

[0007] The imaging system of the present invention comprises a plurality of cameras arranged to image the subject from different directions along the subject's path of movement, each of which includes an image sensor that outputs image data including an image of the subject moving along the path of movement, a plurality of opposing lighting devices arranged opposite each of the plurality of cameras across the path of movement of the subject and which illuminate each of the plurality of cameras with light, and a control device that controls the operation of each of the plurality of cameras and the plurality of opposing lighting devices, and the control device controls the plurality of cameras and the plurality of opposing lighting devices so that each pair of the cameras and the opposing lighting devices arranged opposite each other are driven synchronously at the same timing, and each of the multiple pairs of cameras and the opposing lighting devices is driven at a different timing.

[0008] The control device controls the driving of the multiple cameras and multiple facing illumination devices that the imaging system has. The imaging system has multiple pairs of cameras and facing illumination devices that are arranged opposite each other. The pair of cameras and the facing illumination devices are driven synchronously by the control device, and the facing illumination devices emit light in accordance with the imaging timing (exposure timing) of the cameras.

[0009] The camera may be driven by a control device, while the opposing lighting device paired with the camera may be driven and controlled by the camera instead of the control device. An imaging system in which the opposing lighting device is controlled by a camera includes a plurality of cameras that are arranged to capture an image of the subject from different directions along the subject's path of movement, each of which includes an image sensor that outputs image data including an image of the subject moving along the path of movement, opposing lighting devices that are arranged opposite each of the plurality of cameras across the path of movement of the subject and irradiate light toward each of the plurality of cameras, and a control device that controls the operation of each of the plurality of cameras, and the control device controls the plurality of opposing lighting devices so that each of the plurality of cameras is driven at a different timing, and controls the plurality of opposing lighting devices so that one of the paired lighting devices arranged opposite the camera irradiates light in synchronization with the timing of each of the plurality of cameras capturing an image of the subject.

[0010] In one embodiment, the subject is a filament having a longitudinal direction along the moving path and moving along the moving path, and the multiple cameras are provided at angular intervals on concentric circles centered on the filament. It is possible to capture an image of the peripheral surface of the filament over a wide range.

[0011] In another embodiment, the subject is a plurality of objects of the same shape moving on the moving path, and the plurality of cameras are provided on either side of the moving path, so that the object moving on the moving path (for example, an object being transported by a conveyor, or an object falling freely) can be imaged from a plurality of directions.

[0012] According to this invention, multiple cameras are arranged to capture images of the subject from different directions along the subject's path of movement, making it possible to obtain images of the subject over a wide range (entire, all around) of the subject, thereby improving the accuracy of subsequent image analysis using image data representing the subject image, such as for visual inspection of the subject and dimensional measurement.

[0013] A pair of cameras and opposing illumination devices are driven synchronously at the same timing, but at a different timing from other pairs of cameras and opposing illumination devices. The light irradiated from the opposing illumination device arranged opposite the camera across the subject's movement path is partially blocked by the subject moving along the movement path, and as a result, a dark image portion (shadow) is formed on the image sensor of the camera in the part where the light is blocked by the subject, and a bright image portion is formed around it. Since a large change in brightness occurs in the part representing the contour (edge) in the subject image formed on the image sensor, a stable (clear) contour of the subject image is captured, and image analysis can be performed with high accuracy. Since light from the opposing illumination devices included in other pairs does not enter, the contour of the subject does not become unclear due to the light from the opposing illumination devices included in other pairs.

[0014] In one embodiment, a time interval longer than the light emission time of the opposing lighting devices is secured between the drive timings of the opposing lighting devices, thereby reliably eliminating the influence of light from the opposing lighting devices included in the other pair.

[0015] Preferably, the exposure times of the multiple cameras and the light emission times of the multiple facing illumination devices are equal. That is, for each pair of camera and facing illumination device, the drive timing of the camera and the facing illumination device are the same, and the drive times (camera image capture (exposure) time, and light emission time of the facing illumination device) are equal. The drive timing of the multiple pairs of cameras and facing illumination devices can be shifted to make them easier to control.

[0016] In one embodiment, a forward lighting device is provided for each of the cameras, which is disposed near the cameras and irradiates light from the camera side toward the subject, and the control device controls the multiple cameras and multiple forward lighting devices so that the cameras and the forward lighting devices are driven synchronously at the same timing and at a timing different from the driving timing of the cameras and the opposing lighting devices. By irradiating light from the camera side toward the subject using the forward lighting device, the state of the surface of the subject can be captured by the camera. Since the cameras and the forward lighting devices are driven synchronously at the same timing and at a timing different from the driving timing of the pair of cameras and opposing lighting devices, the forward lighting device does not make the outline of the subject image described above difficult to understand. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a block diagram showing the hardware configuration of a wire rope image measuring device according to a first embodiment. [Diagram 2] FIG. 1 is a block diagram showing the hardware configuration of a wire rope image measuring device according to a first embodiment. [Diagram 3] 4 is a timing chart for driving the digital camera and the facing illumination device. [Figure 4] A wire rope silhouette image is shown. [Diagram 5] A wire rope silhouette image is shown. [Figure 6] A wire rope silhouette image is shown diagrammatically. [Figure 7] 1 is a schematic diagram showing a wire rope image in which the right and left edges of the wire rope silhouette image are represented by solid lines. [Figure 8] FIG. 13 is a block diagram showing a hardware configuration of an image measuring device according to a modified example of the first embodiment. [Figure 9] FIG. 13 is a block diagram showing a hardware configuration of an image measuring device according to a modified example of the first embodiment. [Figure 10]FIG. 13 is a block diagram showing a hardware configuration of an image measuring device according to still another modified example of the first embodiment. [Figure 11] FIG. 13 is a block diagram showing a hardware configuration of an image measuring apparatus according to a second embodiment. [Figure 12] FIG. 13 is a block diagram showing a hardware configuration of an image measuring apparatus according to a second embodiment. [Figure 13] 4 is a timing chart for driving the digital camera, the facing lighting device, and the front lighting device. [Figure 14] Wire rope image is shown. [Figure 15] Wire rope image is shown. EXAMPLES

[0018] 1 and 2 are block diagrams showing the hardware configuration of a wire rope image measuring device.

[0019] The image measuring device for the wire rope includes an imaging system and a recording / analysis device 45. The imaging system includes a pair of a first digital camera 11 and a first opposing illumination device 13 arranged opposite each other across a travel path (movement path) on which the wire rope 1 travels, a pair of a second digital camera 21 and a second opposing illumination device 23 similarly arranged opposite each other across the wire rope 1, lenses 12, 22 provided in front of the first and second digital cameras 11, 21, and a synchronization signal circuit 40.

[0020] A first digital camera 11 is disposed facing each other on one side of a path along which a wire rope 1 (shown as a circular cross section in Figs. 1 and 2) that is the object to be measured passes, and a first opposing illumination device 13 is disposed facing each other on the other side. A part of the light emitted from the first opposing illumination device 13 is blocked by the wire rope 1, and the light that is not blocked by the wire rope 1 is received by an image sensor (not shown) of the first digital camera 11 via a lens 12 (Fig. 1). Similarly, a second digital camera 21 and a second opposing illumination device 23 are disposed facing each other across the path along which the wire rope 1 passes, and a part of the light emitted from the second opposing illumination device 23 is blocked by the wire rope 1, and the light that is not blocked by the wire rope 1 is received by an image sensor (not shown) of the second digital camera 21 via a lens 22 (Fig. 2).

[0021] The direction connecting the first digital camera 11 and the first opposed lighting device 13 and the direction connecting the second digital camera 21 and the second opposed lighting device 23 are mutually perpendicular, and the first and second digital cameras 11, 21 and the first and second opposed lighting devices 13, 23 are all arranged on concentric circles centered on the wire rope 1, and the distance between the image sensor of the first digital camera 11 and the wire rope 1 is equal to the distance between the image sensor of the second digital camera 21 and the wire rope 1. The wire rope portion (surface) imaged by the first digital camera 11 and the wire rope portion (surface) imaged by the second digital camera 21 are different from each other.

[0022] A telecentric lens is preferably used for the lenses 12 and 22. By using a telecentric lens, only light incident parallel to the optical axis of the lenses 12 and 22 is focused on the image sensors provided in the first and second digital cameras 11 and 21, making it possible to obtain an undistorted image of the subject.

[0023] The image sensor of the first and second digital cameras 11 and 21 may be an area sensor in which a plurality of image pickup elements are arranged two-dimensionally in the vertical and horizontal directions, or may be a line sensor having a plurality of image pickup elements arranged in the horizontal direction. The image pickup elements may be C-MOS (Complementary Metal-Oxide Semiconductor) elements or CCD (Charge-Coupled Device) elements. The frame rate of the image sensor can be set arbitrarily according to the running speed of the traveling wire rope 1, and the wire rope 1 is imaged at a frame rate of, for example, about 10 to 500 fps. The number of pixels of the image sensor is arbitrary, but the more pixels there are, the more detailed (finer) the image analysis described below can be performed.

[0024] The image data output from the first and second digital cameras 11 and 21 is transmitted to the recording / analysis device 45 (the recording / analysis device 45 is illustrated only in FIG. 1). The recording / analysis device 45 is a computer device that executes image analysis processing of the wire rope 1 based on the image data (measurement of the diameter d of the wire rope 1 using the image, measurement of the length M between adjacent peaks formed on the surface of the wire rope 1, etc.) including a CPU (Central Processing Unit) that controls the overall operation of the recording / analysis device 45, a memory that temporarily stores various data, a storage medium that stores various data, a communication device for data communication with the first and second digital cameras 11 and 21, and the image analysis processing of the wire rope 1 based on the image data (measurement of the diameter d of the wire rope 1 using the image, measurement of the length M between adjacent peaks formed on the surface of the wire rope 1, etc.). The image data transmitted from the first and second digital cameras 11 and 21 is stored in the storage medium of the recording / analysis device 45, and image analysis of the wire rope 1 is executed using the image data stored in the storage medium. In addition to the image data transmitted from the first and second digital cameras 11 and 21, the storage medium of the recording / analysis device 45 also stores a program for causing the recording / analysis device 45 to execute analysis processing, an operating system program, etc.

[0025] 1 and 2, the first digital camera 11 and the first facing illumination device 13, and the second digital camera 21 and the second facing illumination device 23 are driven synchronously at different timings. The synchronous driving of the first digital camera 11 and the first facing illumination device 13, and the synchronous driving of the second digital camera 21 and the second facing illumination device 23 are controlled by a synchronization signal output from a synchronization signal circuit 40.

[0026] The synchronization signal circuit 40 includes an oscillator that generates a reference signal of a predetermined frequency, and a part of the reference signal generated by the oscillator is used as a synchronization signal provided to the first and second digital cameras 11, 21, and the first and second facing illumination devices 13, 23. The first and second digital cameras 11, 21, and the first and second facing illumination devices 13, 23 are all driven at timings according to the synchronization signal output from the synchronization signal circuit 40.

[0027] FIG. 3 shows a timing chart of the driving of the first and second digital cameras 11, 21 and the first and second facing illumination devices 13, 23 in accordance with the synchronization signal provided by the synchronization signal circuit 40. In FIG.

[0028] The first digital camera 11 and the first opposed lighting device 13 are provided with synchronization signals S1 and S3 at the same timing from the synchronization signal circuit 40, which causes the first digital camera 11 and the first opposed lighting device 13 to operate at the same timing (Fig. 1). Similarly, the second digital camera 21 and the second opposed lighting device 23 are provided with synchronization signals S2 and S4 at the same timing from the synchronization signal circuit 40, which causes the second digital camera 21 and the second opposed lighting device 23 to operate at the same timing (Fig. 2).

[0029] The period of the synchronization signals S1, S3 given to the first digital camera 11 and the first facing illumination device 13 is equal to the period of the synchronization signals S2, S4 given to the second digital camera 21 and the second facing illumination device 23, and has a period of, for example, 2.5 msec. On the other hand, the timing of the synchronization signals S1, S3 given to the first digital camera 11 and the first facing illumination device 13 and the synchronization signals S2, S4 given to the second digital camera 21 and the second facing illumination device 23 is shifted by a predetermined time, for example, 0.5 msec.

[0030] For example, 0.5 msec after a synchronization signal S1 is given to the first digital camera 11 and the first opposed lighting device 13, a synchronization signal S2 is given to the second digital camera 21 and the second opposed lighting device 23. Similarly, 0.5 msec after a synchronization signal S3 is given to the first digital camera 11 and the first opposed lighting device 13, a synchronization signal S4 is given to the second digital camera 21 and the second opposed lighting device 23. The time difference (drive time interval) between the synchronization signals S1 and S2, and the time difference between the synchronization signals S3 and S4 are ensured to be longer than the exposure time (e.g., 0.2 msec) of the first and second digital cameras 11, 21 and the light emission time (e.g., 0.2 msec) of the first and second opposed lighting devices 13, 23. As a result, the first digital camera 11 and the first opposing illumination device 13 are driven, and after the wire rope 1 is imaged by the first digital camera 11 under illumination by the first opposing illumination device 13, the wire rope 1 can be imaged by the second digital camera 21 under illumination by the second opposing illumination device 23 without being affected by the illumination by the first opposing illumination device 13. When the wire rope 1 is imaged by the second digital camera 21, the first opposing illumination device 13 that does not face the second digital camera 21 is turned off and is not affected by the light from the first opposing illumination device 13, so that the contour of the wire rope imaged by the second digital camera 21 is prevented from becoming unclear. The first digital camera 11 can also image the wire rope 1 without being affected by the light from the second opposing illumination device 23 that does not face the first digital camera 11.

[0031] Instead of providing synchronization signals S1, S3 from synchronization signal circuit 40 to both first digital camera 11 and first opposed illumination device 13, synchronization signals S1, S3 may be provided only to first digital camera 11, and when synchronization signal S1 is provided, a control signal may be output from first digital camera 11 to first opposed illumination device 13, causing light to be emitted from first opposed illumination device 13 in conjunction with the exposure of first digital camera 11. The same applies to second digital camera 21 and second opposed illumination device 23.

[0032] Fig. 4 shows an image 51 of the wire rope 1 captured by the first digital camera 11 under illumination by the first opposing illumination device 13. Fig. 5 shows an image 52 of the wire rope 1 captured by the second digital camera 21 under illumination by the second opposing illumination device 23 at a timing (e.g., the relationship between the synchronization signals S1 and S2 shown in Fig. 3) immediately after capturing the wire rope image 51 shown in Fig. 4.

[0033] Since the first digital camera 11 is installed on one side of the wire rope 1 and the first facing lighting device 13 is installed on the other side (see Fig. 1), the wire rope image 51 captured by the first digital camera 11 includes a dark image portion (hereinafter referred to as a wire rope silhouette image 51A) where the light irradiated from the first facing lighting device 13 is blocked by the wire rope 1 and a bright image portion (hereinafter referred to as a background image 51B) surrounding the dark image portion. The first digital camera 11 is installed so that the entire width of the wire rope 1 is captured as shown in Fig. 4.

[0034] Referring to Figure 5, the second digital camera 21 and the second opposing lighting device 23 are also installed on opposite sides of the wire rope 1 (see Figure 2), so the wire rope image 52 captured by the second digital camera 21 also includes a wire rope silhouette image 52A and the bright background image 52B surrounding it.

[0035] Since the first digital camera 11 and the second digital camera 21 are arranged perpendicular to each other with respect to the wire rope 1 (FIGS. 1 and 2), the second digital camera 21 can capture an image of a range that cannot be captured by the first digital camera 11, and conversely, the first digital camera 11 can capture an image of a range that cannot be captured by the second digital camera 21. Since the outline of almost the entire circumference of the wire rope 1 can be captured using the two digital cameras 11 and 21, it is possible to improve the accuracy of, for example, image measurement and quality inspection of the wire rope 1 based on the measurement results.

[0036] Since the wire rope 1 is running and the drive timing of the first digital camera 11 and the second digital camera 21 is shifted, the wire rope silhouette image 51A shown in FIG. 4 and the wire rope silhouette image 52A shown in FIG. 5 do not strictly capture the same position of the wire rope 1 (the same position in the longitudinal direction of the wire rope 1). However, if the running speed of the wire rope 1 is, for example, 30 m / min, the movement distance of the wire rope 1 during the time period of 0.5 msec from when the first digital camera 11 is driven until the second digital camera 21 is driven is 0.25 mm. The dimensions of a typical wire rope 1 are a diameter of 14 mm, and the spacing between the crests is about 14.47 mm (when the number of strands is six), and a deviation of about 0.25 mm can be considered to be minute, and there is no problem in considering that the wire rope silhouette image 51A shown in FIG. 4 and the wire rope silhouette image 52A shown in FIG. 5 capture the same position of the wire rope 1.

[0037] The image data output from the first and second digital cameras 11, 21 is recorded in a storage medium of the recording / analysis device 45. Using the image data recorded in the storage medium, for example, the diameter d of the wire rope 1 can be calculated.

[0038] Since the wire rope 1 is made by twisting together multiple strands (for example, six strands), a spiral valley portion (groove portion, nip) is formed at the boundary between adjacent strands, and a peak portion (crown) is formed between the valley portions. In measuring the diameter d of the wire rope 1, the diameter of the circumscribed circle of the cross section of the wire rope 1 along the peak portion of the wire rope 1 is used. In the measurement process of the diameter d of the wire rope 1 using image data executed by the recording / analysis device 45, the image portion corresponding to the peak portion of the wire rope 1 is also used to calculate the diameter d.

[0039] A method for calculating diameter d using a wire rope image will be described with reference to Figures 6 and 7. Figure 6 shows a schematic diagram of a wire rope image (frame image) 53 represented by image data output from the first and second digital cameras 11 and 21. Wire rope image 53 includes a wire rope silhouette image 53A (both the left and right edges). Figure 7 shows wire rope image 53 in which the right and left edges of wire rope silhouette image 53A, obtained as described below, are represented by solid lines.

[0040] Wire rope image 53 includes a plurality of line-unit images (hereinafter referred to as line images). The left edge position and the right edge position of wire rope silhouette image 53A are determined using each of the line images (for example, the position where the brightness changes is determined as the left edge position and the right edge position). In addition, a position equidistant from the determined left edge position and the right edge position is determined as the midpoint. Center line 53B (shown by a dashed line in FIG. 7) of wire rope silhouette image 53A is calculated from the multiple midpoints obtained for each of the multiple line images.

[0041] By determining the left edge position and the right edge position for all line images included in the wire rope image 53, edge curves similar to sine curves are drawn on each of the left edge and the right edge of the wire rope silhouette image 53A as shown in Fig. 7. This is because, as described above, the wire rope 1 is constructed by twisting together a plurality of strands, and peaks and valleys appear repeatedly on the surface of the wire rope 1 along the longitudinal direction of the wire rope 1.

[0042] For example, by drawing a straight line (edge ​​straight line) for the right edge curve using the least squares method, multiple intersections between the right edge curve and the edge straight line are generated. The midpoints of two adjacent intersections can be determined as the peak (where the apex of the peak is located) and the valley (where the apex of the valley is located). The positions of the peak and valley are determined similarly for the left edge curve.

[0043] The maximum distance L from the center line 53B through the midpoint to the right edge curve R and the maximum distance L from the center line 53B through the midpoint to the left edge curve L The sum of these is determined to be the wire rope diameter d.

[0044] When the wire rope image 53 includes multiple peaks, the pitch of the wire rope 1 can also be calculated from the distance M between adjacent peaks.

[0045] For example, if a break occurs in the wire rope 1, the diameter d of the wire rope 1 calculated using the wire rope image of the location where the break occurred may become extremely large (see Figure 4). The above-mentioned calculation process of the diameter d of the wire rope 1 can also be used to detect abnormalities occurring in the wire rope 1.

[0046] 8 and 9 are block diagrams showing the hardware configuration of an image measuring device according to a modified example of the first embodiment.

[0047] 8 and 9 differs from the imaging system of the first embodiment (FIGS. 1 and 2) in that the first digital camera 11 and the second digital camera 21 are not arranged perpendicular to the wire rope 1, but are arranged at an angle of 120 degrees apart. As in the imaging system of the modified example of the first embodiment, the first and second digital cameras 11 and 21 do not necessarily have to be arranged perpendicular to each other, and even in this case, the second digital camera 21 can capture an image of a range that cannot be captured by the first digital camera 11.

[0048] FIG. 10 is a block diagram showing a hardware configuration of a wire rope image measuring device according to still another modified example of the first embodiment.

[0049] The image measuring device shown in FIG. 10 includes a first digital camera 11 and a first opposing illumination device 13, and a second digital camera 21 and a second opposing illumination device 23, which are arranged to face each other across the wire rope 1, as well as a third digital camera 31 and a third opposing illumination device 33, which are similarly arranged to face each other across the wire rope 1. The first, second, and third digital cameras 11, 21, and 31 are arranged around the wire rope 1 at angular intervals of 120 degrees. The first, second, and third opposing illumination devices 13, 23, and 33 are also arranged around the wire rope 1 at angular intervals of 120 degrees. A lens 32 is also provided in front of the third digital camera 31. A synchronization signal is also provided to the third digital camera 31 and the third opposing illumination device 33 from the synchronization signal circuit 40.

[0050] By providing three digital cameras 11, 21, and 31, the appearance of the wire rope 1 can be captured with even greater accuracy, thereby improving the accuracy of image measurement and quality inspection of the wire rope 1 based on the measurement results.

[0051] As for the imaging system including the third digital camera 31 and the third opposing illumination device 33, similarly to the imaging system of the first embodiment, the third digital camera 31 and the third opposing illumination device 33 are given a synchronization signal at the same timing from the synchronization signal circuit 40, and as a result, the third digital camera 31 and the third opposing illumination device 33 are driven at the same timing. Also, the third digital camera 31 and the third opposing illumination device 33 are driven at a timing different from the drive timing of the first digital camera 11 and the first opposing illumination device 13 and the drive timing of the second digital camera 21 and the second opposing illumination device 23, and as in the first embodiment, a drive time difference longer than the exposure time of the first, second, and third digital cameras 11, 21, and 31 and the light emission time of the first, second, and third opposing illumination devices 13, 23, and 33 is secured. As a result, only the third opposing illumination device 33 emits light at the timing when the third digital camera 31 is exposed, and a clear outline can also be captured for the wire rope image captured by the third digital camera 31.

[0052] 11 and 12 are block diagrams showing the hardware configuration of the image measuring device for a wire rope of the second embodiment. It differs from the image measuring device of the first embodiment (FIGS. 1 and 2) in that a first forward lighting device 14 is provided around the lens 12 provided in front of the first digital camera 11, and a second forward lighting device 24 is also provided around the lens 22 provided in front of the second digital camera 21. The synchronization signal from the synchronization signal circuit 40 is also given to the first and second forward lighting devices 14 and 24.

[0053] The first and second front lighting devices 14, 24 have an annular (frame-like) shape and irradiate light forward of the first and second digital cameras 11, 21 without blocking the fields of view of the first and second digital cameras 11, 21. The first and second front lighting devices 14, 24 irradiate light onto the surface of the wire rope 1 facing the first and second digital cameras 11, 21.

[0054] FIG. 13 shows a timing chart of the driving of the first and second digital cameras 11, 21, the first and second facing illumination devices 13, 23, and the first and second front illumination devices 14, 24 in accordance with the synchronization signal provided by the synchronization signal circuit 40.

[0055] The first facing illumination device 13 and the first forward illumination device 14 are driven at a period (e.g., 5 msec) twice the shooting period (e.g., 2.5 msec) of the first digital camera 11. This causes the first digital camera 11 to alternately capture images of the wire rope 1 under illumination by the first facing illumination device 13 (at the timing of synchronization signals S1 and S5 in FIG. 13) and images of the wire rope 1 under illumination by the first forward illumination device 14 (at the timing of synchronization signal S3 in FIG. 13). Similarly, the second facing illumination device 23 and the second forward illumination device 24 are driven at a period twice the shooting period of the second digital camera 21, and the second digital camera 21 also alternately captures images of the wire rope 1 under illumination by the second facing illumination device 23 (at the timing of synchronization signals S2 and S6 in FIG. 13) and images of the wire rope 1 under illumination by the second forward illumination device 24 (at the timing of synchronization signal S4 in FIG. 13).

[0056] In the second embodiment as well, the timing of the synchronization signals S1, S2, S3, S4, S5, and S6 are set so as not to overlap with each other, taking into account the exposure times of the first and second digital cameras 11, 21 and the light emission times of all lighting devices 13, 14, 23, and 24. As a result, for example, when the first digital camera 11 is capturing an image of the wire rope 1 under the illumination of the first front lighting device 14 (the timing of the synchronization signal S3), the other lighting devices 13, 23, and 24 are turned off.

[0057] Fig. 14 shows an image 54 of the wire rope 1 captured by the first digital camera 11 under illumination by the first forward lighting device 14. Fig. 15 shows an image 55 of the wire rope captured by the second digital camera 21 under illumination by the second forward lighting device 24 at a timing immediately after capturing the wire rope image 54 shown in Fig. 14. It is possible to capture a surface image of the wire rope 1 without blurring the image contour and without increasing the number of digital cameras.

[0058] In the above embodiment, the wire rope 1 is the object to be measured, but it goes without saying that the object to be measured can be a linear body other than the wire rope 1, such as a pipe, cable, etc. Furthermore, the above-mentioned image measuring device (imaging system) can also be used for visual inspection of cans, bottles, and other containers (for example, measuring the dimensions, inspecting the shape, and inspecting for foreign bodies of cans using a silhouette image obtained by imaging a can transported on a belt conveyor), and for inspection of screws, bolts, nuts, connectors, etc. (for example, counting the number of multiple screws of the same shape and inspecting for foreign bodies using a silhouette image obtained by imaging a screw that is falling freely). [Explanation of symbols]

[0059] 1 Wire rope 11,21,31 Digital Camera 12,22,32 Lens 13, 23, 33 Facing lighting device 14,24 Front lighting device 40 Synchronization signal circuit (control device) 45 Recording / analysis equipment 51,52,53,54,55 Wire rope images 51A, 52A, 53A Wire rope silhouette image 51B,52B Background image 53B Wire rope silhouette image center line

Claims

1. a plurality of cameras provided to capture images of the subject from different directions along a path of the subject, each of the cameras including an image sensor that outputs image data including an image of the subject moving along the path of the subject; a plurality of opposed illumination devices that are provided opposite to each of the plurality of cameras across a moving path of the subject and that irradiate light toward each of the plurality of cameras; a front lighting device arranged near each of the plurality of cameras and configured to irradiate light from the camera side toward the subject; and a control device for controlling the operation of each of the plurality of cameras, the plurality of facing lighting devices, and the plurality of forward lighting devices; The control device controls the multiple cameras, the multiple facing lighting devices, and the multiple forward lighting devices so that a pair of the cameras and the facing lighting devices provided opposite each other are driven in synchronization with the same timing, and each of the multiple pairs of the cameras and the facing lighting devices are driven at different timings, and the camera and a pair of the forward lighting devices nearby are driven in synchronization with the same timing, and each of the multiple pairs of the cameras and the forward lighting devices are activated at different timings, and the pair of the camera and the forward lighting device is driven at a timing different from the drive timing of the pair of the camera and the facing lighting device, Imaging system.

2. a time interval longer than the light emission time of the opposing lighting devices is secured between the drive timings of the opposing lighting devices; The imaging system according to claim 1 .

3. the exposure times of the cameras and the light emission times of the facing illumination devices are equal; 3. The imaging system according to claim 1.

4. a plurality of cameras provided to capture images of the subject from different directions along a path of the subject, each of the cameras including an image sensor that outputs image data including an image of the subject moving along the path of the subject; an opposed lighting device provided opposite each of the plurality of cameras across a moving path of the subject, the opposed lighting device irradiating light toward each of the plurality of cameras; a front lighting device arranged near each of the plurality of cameras and configured to irradiate light from the camera side toward the subject; and A control device for controlling the operation of each of the plurality of cameras, The control device includes: Controlling the plurality of cameras so that each of the plurality of cameras is driven at a different timing, Each of the multiple cameras is a plurality of opposed lighting devices and a plurality of forward lighting devices are controlled so that one of a pair of opposed lighting devices provided opposite the camera and one of a pair of forward lighting devices provided near the camera alternately irradiates light at different timings in synchronization with a timing of capturing an image of a subject; Imaging system.

5. the subject is a linear body having a longitudinal direction along the moving path and moving along the moving path, The plurality of cameras are arranged at angular intervals on concentric circles centered on the umbilical member. The imaging system according to claim 1 .

6. the subject is a plurality of objects of the same shape moving on the moving path, The plurality of cameras are provided on either side of the path of movement. The imaging system according to claim 1 .

Images