Shooting system, visual inspection system, and image acquisition method

Abstract

This invention provides a technology for a photographing system that photographs a subject moving along a transport path, which reduces the constraints on installation along the transport path and eliminates synchronization errors with the transport of the subject. [Solution] A shooting system comprising: a camera for photographing an object moving along a transport path; a sensor for measuring a physical quantity for calculating the amount of movement of the object without contacting either the transport mechanism of the transport path or the object; and a shooting control unit for calculating the amount of movement based on the physical quantity and determining the timing of shooting by the camera based on the amount of movement.

Description

Technical Field

[0006]

[0001] The present invention relates to a photographing system for photographing a subject flowing on a conveyance path, an appearance inspection system using the photographing system, and a method for acquiring an image of a subject.

Background Art

[0002] Conventionally, there has been known an appearance inspection apparatus that irradiates an inspection object flowing on a conveyance path with illumination light and photographs it with a camera, and inspects the inspection object based on an image of the inspection object (for example, Patent Documents 1, 2, etc.).

[0003] In such an appearance inspection apparatus, since an inspection object conveyed in a certain direction is photographed by a line sensor camera, if the conveyance speed (conveyance amount) and the interval of photographing by the camera (scan rate) are not appropriate, an image suitable for inspection cannot be obtained. Therefore, it is necessary to synchronize the conveyance speed of the inspection object and the scan rate of the camera.

[0004] As a method for synchronizing the conveyance speed of the inspection object and the scan rate of the camera, it has been conventionally known to install a rotary encoder on the rotation axis of a conveyance mechanism or the like, and determine the timing of photographing by the camera (input a trigger signal to the camera) based on an output signal (pulse) of the rotary encoder (Non-Patent Documents 1, 2, etc.). FIG. 8 shows a schematic diagram for explaining an appearance inspection system 9 employing such a conventional photographing system.

[0005] FIG. 8 shows an outline of an appearance inspection system 9 that photographs a sheet-like inspection object T while conveying it, and inspects defects (foreign matter inclusion, scratches, dirt, etc.) in the inspection object T based on the photographed image. The inspection object T is a sheet-like article and is fed out from a feed roll 41 from a state of being wound in a roll shape, and is conveyed in the direction of the white arrow in the figure by a dancer roll DR and a plurality of conveyance rolls R, and is wound around a take-up roll 42.

[0006] Camera 99 is, for example, a line sensor camera, equipped with multiple image sensors arranged in a line perpendicular to the sheet transport direction. The object to be inspected T is photographed by camera 99 in the imaging area P during transport, and the captured image is output to the inspection device 92, where inspection is automatically performed based on pre-set inspection criteria. Here, since the object to be inspected T is always transported in the direction of the white arrow, if the timing of movement in the transport direction does not match the timing of photography by camera 99, problems such as missing parts in the captured image or overlapping images causing the image to stretch will occur.

[0007] Therefore, in the visual inspection system 9, a rotary encoder 91 is installed on the axis of the measuring roll 90, which is one of the transport rolls. The rotary encoder 91 measures the rotational speed of the measuring roll 90 and transmits an output signal to the inspection device 92. The inspection device 92 calculates the transport speed of the object to be inspected T based on the output of the rotary encoder 91 and synchronizes the timing of the camera 99's photography with this speed. The system determines the value and outputs the signal to the camera 99. With such a system, it is possible to synchronize the transport speed of the object under inspection T with the timing of the image capture to obtain an image suitable for inspection. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2015-172519 [Patent Document 2] Japanese Patent Publication No. 2016-109495 [Non-patent literature]

[0009] [Non-Patent Document 1] Okabe Machinery Industry Co., Ltd., "Synchronization with the conveyor system is essential when using a line scan camera", [online], ImageInspection.COM, [Retrieved August 5, 2024], Internet<URL:https: / / gazou-kensa.com / camera / 136 / > [Non-Patent Document 2] Hutech Co., Ltd., "Surface Inspection Device", [online], [Retrieved August 5, 2024], Internet<URL:https: / / www.futec.co.jp / products / surface> [Overview of the project] [Problems that the invention aims to solve]

[0010] However, in practice, constraints on the transport route (e.g., the product manufacturing line) that transports the object under inspection often make it difficult to find a suitable location for the rotary encoder and to ensure its specifications are compatible (e.g., how many pulses are needed for a given diameter of the roll on which the encoder is mounted), making the introduction of an imaging system challenging.

[0011] Furthermore, various factors can cause a discrepancy between the movement of the object being inspected and the timing of the trigger signal to the line sensor camera. For example, slippage may occur on the roll where the rotary encoder is installed, or if the object being inspected is in sheet form, slack or tension may occur during transport, causing the movement amount and the pulse of the rotary encoder to not match. In such cases, it may not be possible to acquire a proper image, resulting in a decrease in inspection accuracy. In particular, when using a TDI (Time Delay Integration) camera equipped with a TDI sensor, inspection can be performed with higher-quality images than when using a normal line sensor camera. However, if the timing of transport and image capture of the object being inspected is not perfectly synchronized, the image will become blurry and inspection will not be possible. Therefore, stricter tracking of transport is required than when using a normal line sensor camera.

[0012] This invention has been made in view of the above circumstances, and aims to provide a technology for a photographing system that photographs a subject moving along a transport path, which reduces the constraints on installation along the transport path and eliminates the error in synchronization between the transport of the subject and the timing of the photograph. [Means for solving the problem]

[0013] To achieve the above objective, the present invention employs the following configuration. That is, A camera that photographs a subject moving along a transport route, A sensor that measures a physical quantity for calculating the amount of movement of the subject without contacting either the transport mechanism constituting the transport path or the subject, The imaging system includes an imaging control unit that calculates the amount of movement based on the aforementioned physical quantity and determines the timing of the camera's shooting based on the amount of movement.

[0014] Here, the sensor only needs to output a signal capable of measuring physical quantities for calculating the amount of movement of the object. For example, it could be a sensor that measures the "transport speed," "acceleration," and "position (distance)" of the object. More specifically, a laser Doppler velocometer could be used, but it is not limited to this. It could also measure physical quantities other than speed, and the velocometer could use radio waves or ultrasound. The transport path could also be, for example, the manufacturing line of the product that will be the object.

[0015] With this configuration, the sensor can calculate the amount of movement of an object without contacting either the transport mechanism or the object itself, significantly reducing the constraints on the sensor's installation location and the effort required to ensure compatibility with the transport mechanism's specifications. For this reason, it can be used, for example, in product manufacturing lines. The imaging system can be easily retrofitted to existing transport routes. Furthermore, the increased flexibility in sensor placement allows sensors to be positioned to measure at (or near) the camera's shooting location, minimizing the discrepancy between the actual movement of the subject and the camera's trigger, which is determined based on the sensor output.

[0016] Furthermore, the camera is a TDI camera equipped with a plurality of line sensors whose longitudinal direction intersects with the transport direction of the subject, and the shooting control unit may determine the timing of shooting by the TDI camera so that each of the plurality of line sensors sequentially photographs the same part of the subject in accordance with the movement of the subject. Note that "intersecting" here does not mean only perfectly orthogonal intersections, but also intersections that are close to orthogonal.

[0017] That is, the camera is equipped with a plurality of line sensors whose longitudinal direction is perpendicular to the transport direction of the subject, and is configured to acquire an image by sequentially integrating the outputs of each line sensor aligned in the transport direction at each shooting timing determined by the trigger generating means, and the shooting control unit may determine the shooting timing so that the plurality of such line sensors photograph the same part of the subject.

[0018] By using such a high-performance camera, clear images can be acquired, and when these images are used to inspect the subject (i.e., the object being inspected), it becomes possible to detect foreign objects and defects as small as a few microns. However, when using a TDI camera for imaging, if the timing of the object's transport and the imaging are not perfectly synchronized, the impact on the image quality will be significant. Therefore, the responsiveness of the imaging trigger to the transport is required to be more stringent than when using a conventional line sensor camera. In this respect, the present invention can minimize the discrepancy between the amount of movement of the transported object and the timing of imaging by the camera, making it suitable for inspection using a TDI camera.

[0019] Further, the camera and the sensor may be configured as an integrated unit. According to such a configuration, the present imaging system can be easily introduced. In addition, means for generating a trigger signal for determining the imaging timing by the camera based on the measurement result by the sensor may also be unitized together. With such a configuration, the present imaging system can be introduced only by installing the unit. However, the generation of the trigger signal may be performed by a separate device (such as an information processing terminal). That is, a separate device receives the output from the sensor, generates a trigger signal based on this, and then transmits the trigger signal to the camera in the unit, so that the imaging timing by the camera may be determined.

[0020] Further, the sensor is a sensor that performs measurement by irradiating a laser, and the camera and the sensor may be arranged in the unit such that the focus of the camera on the subject coincides with the focus of the irradiated light of the laser.

[0021] Here, the "coincidence" is not limited to the case of exact coincidence without any difference, but also includes the case of being approximated to such an extent that it can be regarded as coincident. According to such a configuration, the labor of making the foci of the camera and the sensor coincide on site when installing the camera and the sensor can be reduced. In addition, since the laser (irradiated light) and its reflected light can be visually observed, by moving the unit while irradiating the conveyed object with the laser, the position where the light beam converges most on the conveyed object (i.e., the focus) can be searched, and the installation position of the unit where the foci of the camera and the laser Doppler velocimeter coincide can be easily determined.

[0022] Further, the position where the physical quantity is measured by the sensor may be set upstream of the imaging position of the camera in the conveyance path. For example, as the sensor, the Doppler effect When using a non-contact speed sensor that measures the speed of a moving object, a delay on the order of microseconds occurs until the reflected wave is detected, the speed is calculated, and the shooting trigger based on this is input to the camera. Although the delay is substantially negligible, when the position where the speed measurement is performed cannot be made to coincide with the shooting position of the camera in the conveyance direction, it is desirable that the position where the speed measurement is performed be upstream rather than downstream of the shooting position of the camera.

[0023] Further, the subject may be a sheet-like article, and the sensor may be provided at a position facing the camera with the subject interposed therebetween. When the conveyed object is a sheet-like article, for example, when inspecting it, the sheet-like article itself is conveyed so as to be fed out from one end side of the conveyance path and wound up at the other end side. In this case, when photographing the front surface side of the sheet with the camera, it is also possible to perform measurement in a non-contact manner on the back surface side. Therefore, even when the sensor cannot be arranged to perform measurement at the same position as the shooting position of the camera on the front surface side, by arranging the sensor to perform measurement at a position facing the camera (i.e., the same position as the shooting location in the conveyance direction) on the back surface side, it is possible to accurately synchronize the movement amount of the subject and the shooting timing of the camera.

[0024] Further, the photographing system may further include an image generation unit that generates a composite image based on the photographed image by the camera, and an image display unit that displays the composite image.

[0025] Further, the present invention can also be regarded as an appearance inspection system including the photographing system as described above and an inspection device that inspects the subject based on the photographed image of the subject.

[0026] Further, the present invention can also be regarded as the following image acquisition method. That is, measuring the movement amount of a subject moving on a conveyance path without contacting either the conveyance mechanism constituting the conveyance path or the subject, Based on the amount of movement, the timing for photographing the subject is determined, The method for acquiring an image of a subject includes taking a picture of the subject moving along the transport path with a camera according to the determined timing.

[0027] Furthermore, each of the above-described configurations and processes can be combined with each other to constitute the present invention, provided that no technical inconsistencies arise. [Effects of the Invention]

[0028] According to the present invention, in a shooting system for photographing a subject moving along a transport path, it is possible to provide a technology that reduces the constraints on installation along the transport path and suppresses errors in synchronization between the transport of the subject and the timing of the photograph. [Brief explanation of the drawing]

[0029] [Figure 1] Figure 1 is a schematic diagram showing the configuration of an appearance inspection system according to Embodiment 1 of the present invention. [Figure 2] Figure 2 is an explanatory diagram illustrating the schematic structure of the TDI camera of Embodiment 1. [Figure 3] Figure 3 is a block diagram showing the hardware configuration of an information processing device according to Embodiment 1 of the present invention. [Figure 4] Figure 4 is a flowchart showing an example of the processing flow performed by the visual inspection system according to Embodiment 1 of the present invention. [Figure 5] Figure 5 is a schematic diagram showing the configuration of the visual inspection management system according to Embodiment 2 of the present invention. [Figure 6] Figure 6 is a schematic diagram showing a modified configuration of the visual inspection management system according to Embodiment 2. [Figure 7] Figure 7 is a flowchart showing another example of the processing flow performed by the visual inspection system according to Embodiment 1 of the present invention. [Figure 8] Figure 8 is a schematic diagram showing the configuration of a conventional visual inspection system. [Modes for carrying out the invention]

[0030] Embodiments of the present invention will be described below with reference to the drawings.

[0031] <Examples of application> The present invention can be applied, for example, to a visual inspection system 1 as shown in Figure 1. Figure 1 is a schematic diagram of the general configuration of the visual inspection system 1 according to this application example. The visual inspection system 1 includes a photography system 30 comprising a photography unit 10 and an information processing device 20, a transport mechanism comprising a feed roll 41, a dancer roll DR, a plurality of transport rolls R, a winding roll 42, and an illumination means (not shown). The transport mechanism forms a transport path for the object to be inspected T.

[0032] The imaging unit 10 is a unit that integrates a laser Doppler velocometer 11 and a TDI camera 12. The laser Doppler velocometer 11 irradiates the object to be measured (moving object) with laser light, receives the reflected light, and measures the speed of the object without contacting it by utilizing the Doppler effect. Since the laser Doppler velocometer 11 is a known technology, a detailed explanation will be omitted.

[0033] Figure 2 is a schematic diagram illustrating the configuration of the TDI camera 12. As shown in Figure 2, the TDI camera 12 is configured such that multiple rows of line sensors 121, each having a longitudinal direction perpendicular to the transport direction of the object T (indicated by the white arrows in Figure 2), are arranged in the transport direction of the object T, so that the entire width of the object T can be captured. In Figure 2, the number of line sensors 121 is schematically shown as three rows, but in reality, the TDI camera 12 according to this embodiment has more line sensors 121 (for example, 64 rows).

[0034] With such a TDI camera 12, a clear and high-quality image of the object T can be acquired by sequentially accumulating the output of each line sensor 121 in the direction of movement in accordance with the movement of the object T under inspection. On the other hand, if there is even a slight discrepancy between the amount of movement of the object T under inspection and the timing of the capture (accumulation of the output of each line sensor 121), the image acquired by the TDI camera 12 will be vertically elongated and blurred.

[0035] Furthermore, even when using conventional line sensor cameras, not just TDI cameras, it has been common practice to install a rotary encoder on the axis of one of the transport rolls R to determine the amount of movement of the subject in order to synchronize the timing of the image capture with the movement of the subject. The rotary encoder is in physical contact with the drive shaft of the transport roll R and generates pulses at a constant pace in accordance with its rotation. On the other hand, the object being inspected experiences slack and tension during transport, so its amount of movement is not constant, and slippage occurs on the transport roll R. As a result, the actual amount of movement of the object being inspected and the pulses of the rotary encoder often do not match, and the measurement accuracy cannot be said to be sufficiently high.

[0036] In this regard, the imaging unit 10 in this application example measures the speed of the object under inspection T in the imaging area P of the TDI camera 12 using a non-contact type speed sensor, the laser Doppler velocometer 11. Therefore, the movement speed of the object under inspection T can be accurately measured without being affected by the slippage of the transport roll or the slack or tension of the object under inspection T. Then, based on the measured movement speed, the exact amount of movement is calculated and the imaging timing of each of the multiple line sensors 121 of the TDI camera 12 is determined. It allows for precise synchronization of timing.

[0037] Furthermore, even when rotary encoders were to be installed, there were often many constraints regarding their installation location, and difficulties were frequently encountered in selecting equipment and ensuring specifications were aligned (configured), such as determining what pulse output frequency was appropriate for the diameter of the conveyor roll to which the encoder was attached.

[0038] In contrast, the imaging unit 10 in this application example integrates the TDI camera 12 and the laser Doppler velocometer 11, eliminating the need to worry about sensor installation and thus eliminating the complexities required to introduce the imaging system 30 into the transport line.

[0039] <Embodiment 1> Next, embodiments of the present invention will be described in more detail with reference to the drawings. The visual inspection system 1 according to this embodiment has the same configuration as that described with reference to Figure 1 in the application example. That is, the visual inspection system 1 includes a photography system 30, a transport mechanism (feed-out roll 41, dancer roll DR, multiple transport rolls R, wind-up roll 42), and lighting means (not shown). Detailed explanations of configurations already described in the application example will be omitted.

[0040] In this embodiment, the object to be inspected T is, for example, a sheet-like article such as paper or film, which is set on the unwinding roll 41 in a rolled state and continuously transported by the transport mechanism to the take-up roll 42 in the direction of the white arrow. During this transport, it is photographed by the TDI camera 12 in the imaging area P. More specifically, the dancer roll DR moves vertically as shown by the black arrow in Figure 1, unwinding the object to be inspected T from the unwinding roll 41, and is sequentially fed by each transport roll R in the transport direction shown by the white arrow in the figure, and finally wound up by the take-up roll 42.

[0041] The imaging unit 10 is configured such that the focal point of the TDI camera 12 and the focal point of the laser Doppler velocometer 11 coincide with the focal point of the light emitted from the object under inspection T. For example, if the focal length of the TDI camera 12 is 200 mm from the lens and the focal length of the laser Doppler velocometer 11 is 40 mm from the laser light-emitting element, the laser Doppler velocometer 11 is positioned to protrude from the lens of the TDI camera 12 to bridge the 160 mm difference.

[0042] Although not shown in the diagram, the imaging unit 10 is equipped with a calculation processing unit that determines the timing of imaging by the TDI camera 12 based on the measurement value of the laser Doppler velocometer 11. Therefore, the imaging unit 10 alone can determine the timing of imaging by the TDI camera 12. In other words, in this embodiment, the imaging unit 10 also functions as the imaging control unit.

[0043] The imaging unit 10 is installed above the transport mechanism so that it can photograph the entire width of the surface of the object T under inspection from above during the transport path. Although not shown, lighting means are also arranged to illuminate the imaging area P.

[0044] The information processing device 20 can be, for example, a general-purpose computer. It receives signals output by the sensor elements of the TDI camera 12 to acquire image data of the object under inspection T, combines these to generate a composite image of the object, and performs an inspection of the object under inspection T based on the composite image and pre-held inspection standards. In other words, the information processing device 20 functions as an inspection device.

[0045] The above composite image is generated sequentially by multiple line sensors equipped in the TDI camera 12. This includes both accumulating brightness values ​​at the same location on the object T under inspection, and stitching together the field of view along a line, obtained by continuously photographing the object T under inspection as it moves in the direction of travel, in chronological order of the images. The information processing device 20 is also equipped with a display device 24a as one of the output IF24s, which will be described later, and the composite image can be displayed on the display device 24a.

[0046] Figure 3 is a block diagram illustrating the schematic hardware configuration of the information processing device 20. As shown in Figure 3, the information processing device 20 includes, as a hardware configuration, a processor 21, memory 22, input interface (IF) 23, output IF 24, and communication IF 25, all interconnected by a connection bus 29.

[0047] The processor 21 can employ any arithmetic processing unit, such as a CPU (Central Processing Unit), an MPU (Micro-Processing Unit), or a DSP (Digital Signal Processor).

[0048] Memory 22 is flash memory, RAM (Random Access Memory), although it is not shown in the diagram. The system includes main memory such as Memory and ROM (Read Only Memory), and auxiliary storage devices such as SSD (Solid State Drive), EPROM (Erasable Programmable ROM), flash memory, USB memory, and SD (Secure Digital) memory card. Memory 22 stores information such as programs executed by the processor 21, data processed by the processor 21, image data captured by the TDI camera 12, and inspection criteria (inspection items, thresholds) used for inspection.

[0049] The program stored in memory 22 is executed by the processor 21, thereby controlling each component of the information processing device 20, and enabling the realization of each functional unit that fulfills a predetermined purpose. For example, in this embodiment, the information processing device 20 realizes the functional unit of the image generation unit. Alternatively, as in other embodiments described later, the arithmetic processing device may realize the functional unit of the shooting control unit. That is, the arithmetic processing device can also determine the timing of shooting by the TDI camera 12.

[0050] Examples of input IF23 include various input devices such as keyboards, mice, cameras, and microphones. Examples of output IF24 include various output devices such as displays, speakers, and printers. A touch panel display can also be used as both an input IF23 and an output IF. The communication IF25 is connected to the shooting unit 10 and may also have appropriate configurations for connecting to other external devices.

[0051] The process of acquiring an image of the object to be inspected T using this visual inspection system 1 will be explained based on the flowchart in Figure 4. As shown in Figure 4, when the sheet-like object to be inspected T is transported along the transport path, the laser Doppler velocometer 11 measures the movement speed of the object to be inspected T, and the amount of movement of the object to be inspected T is calculated based on this (S1). Then, based on the amount of movement calculated in step S1, the calculation processing unit (not shown) of the imaging unit 10 determines the timing of the imaging by the TDI camera 12 (S2). Subsequently, according to the imaging timing determined in step S2, the TDI camera 12 performs imaging with each sensor element (S3), and the captured data is transmitted to the information processing device 20 (S4).

[0052] Each of the above steps S1 to S4 is repeated until the entire object T to be inspected has been transported (branching to NO at S5). Then, once the entire object T to be inspected has been transported (branching to YES at S5), the information processing device 20 synthesizes the captured data to generate a composite image (S6 Based on the synthesized image and predetermined inspection criteria held in advance by the information processing device, the object T to be inspected is inspected (defect detection) (S7), and the series of processes is completed.

[0053] The above processing procedure is merely an example, and the generation and inspection of the composite image may be performed at any point before the entire transport of the object T under inspection is completed. Furthermore, the procedure may include a step of displaying the composite image, inspection results, etc., on the display device 24a.

[0054] With the visual inspection system 1 configured as described above, the imaging unit 10 is configured so that the focus of the TDI camera 12 and the focus of the laser Doppler velocometer 11 coincide. Therefore, when introducing the imaging system 30 into the transport path of the object to be inspected T, the effort of aligning the focus of the TDI camera 12 and the laser Doppler velocometer 11 on-site is eliminated. Furthermore, since the light emitted from the laser Doppler velocometer 11 and its reflected light can be visually observed, by moving the imaging unit 10, which integrates the camera and velocity sensor, while irradiating the object to be inspected T with the laser, the position where the light beam converges most (i.e., the focal point) on the object to be inspected T can be searched, and the installation position of the imaging unit 10 can be easily determined.

[0055] <Embodiment 2> Next, other embodiments of the present invention will be described with reference to Figure 5. The visual inspection system 2 according to this embodiment has a configuration that is generally the same as the visual inspection system 1 of Embodiment 1. In the following, the same reference numerals will be used for components that have already been described in Embodiment 1, and further explanation will be omitted. Figure 5 is a schematic diagram showing the general configuration of the visual inspection system 2 according to this embodiment.

[0056] As shown in Figure 5, in the visual inspection system 2 according to this embodiment, the TDI camera 12 and the laser Doppler velocometer 11 are configured as separate units, and the laser Doppler velocometer 11 is positioned opposite the TDI camera 12 with the object to be inspected T in between. That is, the laser Doppler velocometer 11 is configured to irradiate the back side of the imaging area P captured by the TDI camera 12 with a laser. In this embodiment, the imaging system 30 is composed of the TDI camera 12, the laser Doppler velocometer 11, and the information processing device 20.

[0057] The measured values ​​from the laser Doppler velocometer 11 are transmitted to the information processing device 20, which calculates the amount of movement of the object under inspection T based on the measured values ​​and generates a trigger signal that determines the timing of the image capture by the TDI camera 12 based on the amount of movement. In other words, in this embodiment, the information processing device 20 (processor 21) corresponds to the image capture control unit. The trigger signal generated by the information processing device 20 is transmitted to the TDI camera 12, and based on this, image capture is performed in synchronization with the movement of the object under inspection T.

[0058] According to the visual inspection system 2 of this embodiment described above, even if the laser Doppler velocometer 11 cannot be positioned on the surface side of the object T to be inspected at the same location as the shooting area P of the TDI camera 12 due to constraints on the installation location, the speed sensor can be positioned on the back side at a location opposite to the TDI camera 12 (i.e., the same location as the shooting area P in the transport direction) to measure the speed, thereby accurately synchronizing the transport speed of the object with the timing of the camera's shooting.

[0059] <Variation> In the above-described visual inspection system 2, the laser Doppler velocometer 11 was positioned opposite the TDI camera 12 and the object under inspection T, but there are no particular restrictions on the placement of the laser Doppler velocometer 11. Figure 6 shows a schematic diagram of a modified visual inspection system 3 in which the placement of the laser Doppler velocometer 11 has been changed.

[0060] As shown in Figure 6, in the modified visual inspection system 3, the laser Doppler velocometer 11 is configured to measure the movement speed of the object under inspection T upstream of the imaging area P by the TDI camera 12.

[0061] When using a non-contact velocity sensor that measures the velocity of a moving object using the Doppler effect, there is a delay of several microseconds between detecting the reflected wave, calculating the velocity, and inputting a shooting trigger based on this to the TDI camera 12. Although this delay is practically negligible, if the position where the velocity is measured cannot coincide with the shooting area P, it is preferable that the position where the velocity is measured be upstream of the shooting area P rather than downstream.

[0062] <Other> The embodiments described above are merely illustrative examples, and the present invention is not limited to the specific forms described above. Various modifications are possible within the scope of its technical concept, beyond the examples described above.

[0063] For example, in the above embodiment 2 and its modified form, the information processing device 20 generated a trigger signal indicating the shooting timing, but the laser Doppler velocometer 11 may have the function of generating such a trigger signal. In that case, the trigger signal may be transmitted directly to the TDI camera 12 without going through the information processing device 20.

[0064] Furthermore, although the information processing device 20 in the above embodiment was configured to include an image generation unit, the shooting unit 10 may also store the shooting data and generate a composite image.

[0065] Furthermore, although the above embodiment employed a TDI camera 12 as the shooting means, the present invention is also applicable to shooting systems using other cameras. When using a TDI camera, it is particularly important to strictly synchronize the timing of shooting with the movement of the subject, but even with a general line sensor camera, the ability to accurately synchronize the timing of shooting with the movement of the subject is an advantage.

[0066] Furthermore, while the above embodiment used a laser Doppler velocometer 11 as the sensor for calculating the amount of movement of the subject, it is not limited to a velocometer, as long as it is a sensor that can calculate the amount of movement of the subject in a non-contact manner. In addition, sensors that measure acceleration or position to calculate the amount of movement of the subject can be used, not limited to light, but also using, for example, radio waves or ultrasound.

[0067] Furthermore, although the above embodiment described an example of offline inspection in which a composite image is generated and inspection is performed after the transport of the object to be inspected T is completed, the object to be inspected T may also be inspected by inline inspection as shown in Figure 7. Below, an example of the processing flow when performing inline inspection will be described based on Figure 7. Note that the processing from step S1 to step S4 is the same as in the embodiment, so the explanation will be omitted.

[0068] In step S4, after the image data is transmitted to the information processing device 20, the information processing device 20 does not determine whether the transfer is complete, but rather determines whether a predetermined amount of image data has been transmitted (S11). If it is determined that a predetermined amount of image data has not been transmitted, the process returns to step S1 and the subsequent processing is repeated (a NO branch occurs in step S11).

[0069] On the other hand, if it is determined in step S11 that a predetermined amount of shooting data has been transmitted, the information processing device 20 generates a composite image with the predetermined amount of data (S12). That is, a predetermined amount of shooting data A composite image is generated showing a portion of the object T to be inspected, corresponding to the data. Then, based on the composite image generated in step S12 and predetermined inspection criteria held in advance by the information processing device 20, the portion of the object T to be inspected is inspected (S13).

[0070] Next, the information processing device 20 determines whether the transport of the entire object T to be inspected has been completed (S14). If it is determined that the transport of the object T to be inspected has not been completed (NO at the S14 branch), the process returns to step S1 and the subsequent processing is repeated. On the other hand, if it is determined in step S14 that the transport of the object T to be inspected has been completed (YES at the S14 branch), the series of processes is terminated. With this type of inline inspection, the transport and photography of the object T to be inspected and the inspection are performed in parallel, so the inspection of the object T to be inspected can be completed soon after the transport of the object T to be inspected is completed.

[0071] Furthermore, while the above embodiment exemplifies a photography system that uses sheet-like objects as subjects, the objects to be photographed are not limited to sheet-like objects. For example, it can also be applied to photography systems that photograph products or fruits and vegetables being transported on a conveyor belt.

[0072] <Note 1> A camera (12) that photographs a subject (T) moving along a transport path, A sensor (11) measures a physical quantity for calculating the amount of movement of the subject without contacting either the transport mechanism constituting the transport path or the subject, The camera has a shooting control unit (20) that calculates the amount of movement based on the physical quantity and determines the timing of the camera's shooting based on the amount of movement. Shooting system (30).

[0073] <Note 2> The camera (12) is a TDI camera equipped with a plurality of line sensors having a longitudinal direction intersecting the transport direction of the subject, in the transport direction, The shooting control unit determines the shooting timing by the TDI camera so that each of the multiple line sensors sequentially photographs the same location on the subject in accordance with the movement of the subject. The shooting system (30) described in Appendix 1.

[0074] <Note 3> The camera (12) and the sensor (11) are configured as an integrated unit (10). The shooting system (30) described in Appendix 1.

[0075] <Note 4> The aforementioned sensor is a sensor that performs measurements by irradiating with a laser, The camera and the sensor are arranged in the unit such that the focus of the camera and the focus of the laser beam coincide with the subject. The shooting system (30) described in Appendix 3.

[0076] <Note 5> The position where the sensor (11) measures the physical quantity is set upstream of the transport path from the camera (12) shooting position (P). The shooting system (30) described in Appendix 1.

[0077] <Note 6> The subject (T) is a sheet-like article, The sensor (11) is positioned opposite the camera (12) with the subject in between. The shooting system (30) described in Appendix 1.

[0078] <Note 7> An image generation unit (20) generates a composite image based on the image captured by the aforementioned camera, The system further includes an image display unit (24a) that displays the composite image, The shooting system described in Appendix 1.

[0079] <Note 8> The shooting system (30) described in any of the appendices 1 to 7, An inspection device that performs an inspection of the subject based on an image of the subject, Visual inspection system (1, 2, 3).

[0080] <Note 9> (S1) The amount of movement of an object moving along the transport path is measured without contacting either the transport mechanism constituting the transport path or the object itself. Based on the amount of movement, the timing for photographing the subject is determined (S2), This includes taking a photograph of the subject moving along the transport path with a camera according to the determined timing (S3), How to acquire images of the subject. [Explanation of Symbols]

[0081] 10. Filming Unit 11. Laser Doppler Velocity Meter 12···TDI camera 121... Line Sensor 20. Information Processing Devices 24a...Image display section 30. Shooting System 41... Feed Roll 42... Reel roll 90... Measuring roll 91. Rotary Encoder 92... Inspection device 99...Camera P... Shooting area R... Conveyor Roll DR...Dancer Roll T...Item under inspection

Claims

1. A camera that photographs a subject moving along a transport route, A sensor that measures a physical quantity for calculating the amount of movement of the subject without contacting either the transport mechanism constituting the transport path or the subject, A shooting control unit that calculates the amount of movement based on the physical quantity and determines the timing of shooting by the camera based on the amount of movement, Shooting system.

2. The camera is a TDI camera equipped with a plurality of line sensors having a longitudinal direction intersecting the transport direction of the subject, in the transport direction, The shooting control unit determines the shooting timing by the TDI camera so that each of the multiple line sensors sequentially photographs the same part of the subject in accordance with the movement of the subject. The imaging system according to claim 1.

3. The camera and the sensor are configured as an integrated unit. The imaging system according to claim 1.

4. The aforementioned sensor is a sensor that performs measurements by irradiating with a laser, The camera and the sensor are arranged in the unit such that the focus of the camera and the focus of the laser beam coincide with the subject. The imaging system according to claim 3.

5. The position in which the sensor measures the physical quantity is set upstream of the camera's shooting position in the transport path. The imaging system according to claim 1.

6. The subject is a sheet-like article, The sensor is positioned opposite the camera with the subject in between. The imaging system according to claim 1.

7. An image generation unit that generates a composite image based on an image captured by the aforementioned camera, The system further includes an image display unit that displays the composite image, The imaging system according to claim 1.

8. A shooting system according to any one of claims 1 to 7, An inspection device that performs an inspection of the subject based on an image of the subject, Visual inspection system.

9. The amount of movement of an object moving along a transport path is measured without contacting either the transport mechanism constituting the transport path or the object itself. Based on the amount of movement, the timing for photographing the subject is determined, This includes taking a photograph of the subject moving along the transport path with a camera according to the determined timing, How to acquire images of the subject.

Images