JP6117580B2 - Inspection equipment - Google Patents

Description

  The present invention relates to an article inspection apparatus that images an article conveyed by a conveyor or the like with a camera and inspects the article based on the obtained image.

  2. Description of the Related Art Conventionally, an article inspection apparatus that inspects an article by imaging an article conveyed by a conveyance apparatus such as a conveyor with an imaging apparatus such as a camera and processing the obtained captured image is known. In such an article inspection apparatus, since it is necessary to take an image at the timing when the entire article enters the field of view of the imaging device, a photoelectric sensor, a proximity sensor, or the like that detects the passage of the article is provided on the article conveyance path. The image is picked up by detecting the timing when the article arrives within the field of view of the image pickup device.

  Further, in Patent Document 1, an article to be conveyed is continuously imaged by an imaging device, a binarization process is performed on the captured image, and an article tip exists in a predetermined region of the obtained processed image. An image processing apparatus that detects whether or not to start and starts predetermined image processing (inspection) only when the tip of the article is detected is disclosed. By doing in this way, the image used for a test | inspection is acquired, without providing the external sensor for detecting the passage of articles | goods.

JP 62-111302 A

  However, when an external sensor is used, if the thickness of the article is thin, it is quite difficult to stably detect the article with the external sensor installed on the side of the conveyor, and there is a problem that it takes time to adjust the article. In order to avoid this problem, a method of detecting an article passing through the connecting portion by installing an external sensor above the gap between the conveyors, that is, the connecting portion, is conceivable. Therefore, there is a risk of erroneous detection in this case.

  Further, as in Patent Document 1, when continuous imaging is performed with an imaging apparatus, the article tip must always exist in a predetermined region in the captured image. However, when the conveying speed of the conveying device is fast and the frame rate of the imaging device (the number of times an image is captured per second) is low, as shown in FIG. There is a possibility of deviating from the area. In that case, although the article to be inspected has arrived, the inspection of the article is not started, so that there is a problem that the uninspected article is mixed in the subsequent process. In order to prevent this problem, it is necessary to use an expensive device with a high frame rate, such as a high-speed camera, in the imaging apparatus, but this hinders the construction of an inexpensive system.

  An object of the present invention is to provide an article inspection apparatus capable of inspecting a conveyed article without providing an external sensor for detecting the passage of the article and without using an expensive device such as a high-speed camera. Is to provide.

An article inspection apparatus according to the present invention is an inspection apparatus that inspects an article based on an obtained image while repeatedly imaging an article conveyed by a conveying means with an imaging means, and a leading end portion of the conveyed article is first An article detection unit that constantly inspects a specific area on an image reflected in the image to notify the arrival of the article, and a time calculation unit that calculates a time from when the arrival of the article is detected until the entire article is reflected on the image A storage unit that stores an image of the calculated time elapsed as an inspection image, and an article inspection unit that inspects the article based on the stored inspection image , wherein the article detection unit includes: An image is generated for a specific area, and the amount of change in brightness of a pixel at the same position is calculated compared to the previously generated image of the specific area, and the amount of change exceeds a predetermined threshold. Count the number of pixels and Determining the arrival of the article when the number exceeds a certain limit.

  The article detection unit always checks a specific area on the image. The specific area is a narrow area in which the front end of the conveyed article is reflected first. And if the front-end | tip part of the conveyed article is caught in the area | region, an article | item detection part will notify arrival of an article | item. The time calculation unit calculates the time from when the article arrives until the entire article is reflected on the image, and operates the timer.When the detected whole article is reflected in the image, the timer is up, An image of the entire article shown in the image is stored as an inspection image. The article inspection unit inspects the article based on the inspection image. Thereby, it is not necessary to install an external sensor for detecting the arrival of the article. In addition, since the arrival of the article is detected by checking only a specific narrow area where the tip of the article is reflected first, the arrival of the article can be reliably detected even if the conveyance speed of the article is increased. Therefore, the detection of the conveyed article and the generation of the inspection image can be realized at a low cost by a single imaging unit without using an expensive device such as a high-speed camera.

  Further, the time calculation unit notifies the time when the article to be conveyed reaches the center position on the image based on the length of the article in the conveyance direction and the conveyance speed of the article by the conveyance unit, and causes the inspection image to be captured. Therefore, it is possible to generate a suitable image in which the article to be inspected is captured at the center position of the captured image. Therefore, subsequent image processing becomes easy.

  According to the article inspection apparatus according to the present invention, an external sensor for imaging an article at an optimal timing can be eliminated. In addition, since the arrival of an article is detected by constantly checking only a limited specific area on the image, the entire article can be detected without using an expensive device such as a high-speed camera even if the article conveyance speed is increased. An image can be projected. Therefore, a system can be constructed at a low cost.

1 is a schematic side view of an embodiment of an article inspection apparatus according to the present invention. FIG. 1 is a configuration block diagram of an article inspection apparatus according to an embodiment. The operation | movement flowchart of the article inspection apparatus which concerns on one Embodiment. Explanatory drawing of the calculation method of the timing which images the image for a test | inspection. Explanatory drawing of the calculation method of the timing which images the image for a test | inspection based on a specific numerical value. Explanatory drawing of the problem of a prior art.

  Hereinafter, an embodiment of an article inspection apparatus according to the present invention will be described with reference to the drawings.

  In FIG. 1, the article inspection apparatus 1 includes a lower housing 2, a light shielding housing 3, and an upper housing 4. A computer 5 that controls the operation of the article inspection apparatus 1 is accommodated in the lower housing 2. A display unit 6 is installed in the upper housing 4. The display unit 6 includes a liquid crystal display device with a touch panel function. The article inspection apparatus 1 is incorporated in a production line for the article 50. The article inspection apparatus 1 inspects the article 50, and if a defective article 50 is found, the article inspection apparatus 1 discharges it out of the line and prevents its shipment.

  The light shielding housing 3 is provided with an article carry-in port 3a and an article carry-out port 3b. In the light-shielding housing 3, a transport conveyor 7 is disposed as a transport unit that transports the article 50 in the direction of the arrow from the article carry-in entrance 3 a toward the article carry-out exit 3 b. The upstream end of the conveyor 7 protrudes outward from the article carry-in port 3a, and the downstream end protrudes outward from the article carry-out port 3b.

  In the light shielding housing 3, a white light source 11 and a camera 12 as an imaging means are arranged. The white light source 11 is disposed above the conveyor 7 and irradiates the article 50 on the conveyor 7 with white light. The white light source 11 is a two-dimensional array of a plurality of LEDs that emit white light.

  In FIG. 2, the camera 12 includes a lens 12a, a plurality of image sensors 12b, and a camera control unit 12c. The camera 12 captures an image of the article 50 transported by the transport conveyor 7 from above the transport conveyor 7 and generates an image. The plurality of imaging elements 12 b are arranged on a plane parallel to the conveyance surface of the conveyance conveyor 7 and images the article 50 conveyed by the conveyance conveyor 7. The plurality of imaging elements 12b convert light incident from the lens 12a into detection signals (electric signals). The camera control unit 12c generates signals by reading out signals from the image pickup devices 12b and developing the read signals in two dimensions in response to commands from an article detection unit 14 and an article inspection unit 15 described later. In the present embodiment, as the camera 12, a general industrial CCD (Charge Coupled Device) camera in which the number of pixels of the image sensor 12b is 640 pixels × 480 pixels and the frame rate is 30 fps is used.

  In FIG. 1, an intake conveyor 20 is installed on the upstream side of the article inspection apparatus 1 incorporated in the production line, and a sorting apparatus 30 is installed on the downstream side. The take-in conveyor 20 transfers the article 50 to the transport conveyor 7 of the article inspection apparatus 1. The sorting apparatus 30 excludes, from the production line, the articles 50 that are determined to be defective by the article inspection apparatus 1 among the articles 50 that have come out of the conveyor 7 of the article inspection apparatus 1.

  In FIG. 3, a computer 5 mounted on the article inspection apparatus 1 includes a CPU, a ROM, a RAM, and the like. By executing a program installed in advance, at least a mode control unit 13, an article detection unit 14, an article inspection is performed. The functions of the unit 15, the time calculation unit 16, and the storage unit 17 are realized. The mode control unit 13 switches the article inspection apparatus 1 between an article detection mode and an article inspection mode described later. The article detection unit 14 always checks a specific area on the image where the article 50 is captured. The specific area is a narrow area on the image in which the tip of the conveyed article is first reflected. And if the front-end | tip part of the conveyed article is caught in the area | region, the article | item detection part 14 will notify arrival of an article | item. The time calculation unit 16 calculates the time from when the article detection unit 14 detects the arrival of the article 50 until the entire article 50 is reflected on the image. The storage unit 17 stores an image when the calculated time has elapsed as an inspection image. The article inspection unit 15 inspects the article 50 based on the inspection image stored in the storage unit 17 and determines whether or not the article 50 has a defect. The mode control unit 13, the article detection unit 14, the article determination unit 15, and the time calculation unit 16 are realized by executing a stored program. The storage unit 17 is configured by a non-volatile memory, a hard disk, or the like, and stores determination images such as inspection images, inspection parameters, and defects of the article 50 inspected by the article inspection unit 15. As inspection parameters, at least the conveyance direction length L of the article 50, the conveyance speed V of the conveyance conveyor 7, and actual dimensions (physical dimensions on the conveyor) corresponding to one side of one square pixel constituting the image. P, a conveyance direction pixel number NX, and a threshold value TH for determining passage of an article 50 described later are stored. In addition, each said parts 13-16 can also be comprised with hardware.

  Although not shown, the computer 5 includes a display control circuit for data to be displayed on the display unit 6, a key input circuit for fetching input data from the touch panel of the display unit 6, and the like. Further, the computer 5 controls a motor control circuit (not shown) for setting the transport speed of the transport conveyor 7 to a set speed.

  Next, a flow from when the passage of the article 50 is detected to when it is determined whether or not the article 50 has a defect will be described using the flowchart shown in FIG. When the article inspection apparatus 1 is operated, the transfer conveyor 7, the front and rear intake conveyors 20 and the sorting apparatus 30 are driven, and the camera 12 starts imaging. Then, until the take-in conveyor 20 sends the article 50 to the transport conveyor 7, the mode control unit 13 sets the article inspection apparatus 1 to the article detection mode.

  In this article detection mode, the article detection unit 14, as shown in the image of FIG. 5, the specific area B on the image A captured by the camera 12, that is, the area where the tip of the article 50 to be conveyed first appears. B is constantly inspected to check whether or not the tip of the article 50 is reflected in the region B. For example, assuming that the image A captured by the camera 12 has a screen A having 480 pixels in the transport direction and 640 pixels in the direction perpendicular to the image A as shown in FIG. 6, the tip of the article 50 appears first. The area to be embedded is a narrow specific area B of 48 pixels in the transport direction from the left end of the image A. About this area | region B, a test | inspection is performed repeatedly and the arrival of the articles | goods 50 is test | inspected. Thus, by inspecting only the narrow specific region B, the presence / absence of the article 50 can be inspected at a high frame rate.

  Since the camera 12 generates an image of 640 pixels × 480 pixels at a frame rate of 30 fps, it is possible to generate an image at a frame rate of 300 fps if the range for reading image data is limited to 640 pixels × 48 pixels. Become. This is because the readout time is reduced to 1/10 since the number of pixels is reduced to 1/10. In the article detection mode, the camera control unit 12c periodically inspects the arrival of the article 50 by inspecting the specific area B (640 pixels × 48 pixels) (frame rate 300 fps). This operation is steps S1 to S4 shown in the flowchart of FIG.

  That is, the article detection unit 14 generates an image for the specific region B (step S1), and then compares the image of the region B generated one frame before with the two images of the region B generated this time. Then, the amount of change in brightness of the pixels at the same position is calculated (step S2). If the change amount exceeds the threshold value TH, the article detection unit 14 counts the number of pixels exceeding the threshold value TH (step S3). If the number of pixels exceeding the threshold TH is equal to or less than a certain number, it is determined that the camera 12 does not capture the article 50. If the number of pixels exceeding the threshold TH exceeds a certain number, the camera 12 captures the article 50. Determine (step S4). Further, the article detection unit 14 transmits the specific area B among the pixels exceeding the threshold value TH to the time calculation unit 16 as the position LA of the tip portion of the article 50. When the article detection unit 14 detects the tip of the article 50, the mode control unit 13 switches from the article detection mode to the article inspection mode.

  In the article inspection mode, the timing at which the center line of the article 50 reaches the center line NA (see FIG. 5) of the image A from the time when the time calculating section 16 first detects the tip of the article 50 by the article detecting unit 14. Is calculated. Specifically, when the time calculation unit 16 receives the position LA of the tip of the article 50 from the article detection unit 14, the conveyance direction length L of the article 50, the number of conveyance direction pixels NX, and the conveyance speed V of the conveyance conveyor 7. , And the actual dimension P is read from the storage unit 17. Using these numerical values, the time calculation unit 16 moves the movement distance LB of the article 50 until the center line of the article 50 matches the center line NA of the image A (= P × NX / 2 + L / 2−P × LA). (See FIG. 5).

  Next, an imaging timing (= LB / V) for capturing the entire image of the article 50 is calculated from the distance LB and the transport speed V of the transport conveyor 7. Here, the time calculation unit 16 calculates the distance LB using the position LA of the front end portion of the article 50. However, if the frame rate of the camera 12 is sufficiently high with respect to the conveyance speed V, the front end portion is calculated from the above formula. The position LA may be omitted (step S5).

  The camera control unit 12c images the article 50 at the calculated imaging timing, and stores all the captured images A in the storage unit 17 as inspection images (step S6).

  The article inspection unit 15 performs image processing on the stored inspection image, and determines whether there is a defect in the article 50 based on the processing result (step S7). The defect of the article is, for example, a date leak to be printed on the article 50, an incorrect date printed, a scratch on the surface of the article 50, or the like. When the computer 5 determines that a defect has occurred in the article 50 by the article inspection unit 15, the computer 5 sends a command to the sorting device 30 and excludes the determination result in order to remove the article 50 from the production line. The data is stored in the storage unit 17. Further, the determination result is displayed on the display unit 6 in accordance with the operation of the operator.

  Next, description will be made by substituting specific numerical values for each inspection parameter. In FIG. 6, a case is considered in which the width of the transfer conveyor 7 is 160 mm, the transfer speed V of the transfer conveyor 7 is 500 mm / s, and the length L of the article 50 in the transfer direction is 80 mm. When the entire width of the conveyor 7 is stored in the image A, the actual dimension P on the conveyor corresponding to one pixel is a square of 0.25 mm (= 160 mm / 640 pixels). As shown in FIG. 6, the position of the pixel that is the most downstream in the transport direction among the plurality of pixels whose change amount exceeds the threshold value TH, that is, the position LA of the tip of the article 50 is an image captured by the camera 12. The position is 40 pixels in the transport direction from the left end side of A. Since the number of pixels NX in the transport direction of the camera 12 is 480 pixels, the distance LB that the article 50 moves until the center line of the article 50 matches the center line of the image A captured by the camera 12 is 90 mm (= P × NX / 2 + L / 2−P × LA). Next, the movement of 90 mm at the conveyance speed V is 0.18 s (= LB / V) later, so in the article detection mode, the camera 12 is triggered 0.18 s after the tip of the article 50 is detected. When the image is input and imaged, an image for inspection in which the image A of the article 50 is located at the center can be generated. Moreover, when the conveyance direction length L of the article 50 is short, the reading range in the conveyance direction may be limited.

  As described above, in the present invention, the article detection unit 14 determines whether or not the tip of the article 50 is captured at a high frame rate by limiting the imaging range. Then, when the tip of the article 50 is detected, the time calculation unit 17 notifies the camera control unit 12c of the timing when the entire article 50 reaches the center of the image A, and captures the article 50 when the timing comes. Thus, an inspection image including the entire article 50 on the image A is generated. Thereby, a single camera can detect and image the article 50 conveyed by the conveyor 7 without providing an external sensor for detecting the article 50 and without using an expensive device such as a high-speed camera. 12 can be realized at low cost. In the present invention, since the imaging timing of the camera 12 is determined based on the length L in the conveyance direction of the article 50 and the conveyance speed V of the conveyance conveyor 7, an image obtained by capturing the article 50 with the camera 12 in the inspection image. It can be projected in the center of A. Therefore, it is possible to determine whether or not the article has a defect with stable image processing.

  As mentioned above, although one embodiment of the present invention has been described, the present invention is not limited to the above embodiment, and instead of using a white light source as the light source, X-rays, near infrared rays, infrared rays, terahertz waves, etc. Irradiation may be performed and the image sensor 12b of the camera 12 may be imaged using a sensor corresponding to each light beam. In this case, the state inside the article 50 can be inspected by detecting the transmitted light of the article 50.

  In the above embodiment, a CCD camera is used as the camera 12, but a CMOS (Complementary Metal Oxide Semiconductor) camera may be used instead of the CCD camera. In the case of a CMOS camera, it is possible to generate an inspection image in which a reading range is limited in a direction perpendicular to the conveyance direction.

1 Item inspection device 7 Conveyor (conveying means)
12 Camera (imaging means)
14 article detection unit 15 article inspection unit 16 time calculation unit 17 storage unit L length of article conveyance direction V conveyance speed of conveyance conveyor

Claims (2)

An inspection apparatus that inspects an article based on an obtained image while repeatedly imaging an article conveyed by a conveying means with an imaging means,
An article detection unit that constantly inspects a specific area on the image where the tip of the article to be conveyed first appears and notifies the arrival of the article;
A time calculator that calculates a time from when the arrival of the article is detected until the entire article is reflected on the image;
A storage unit that stores an image at the calculated time as an inspection image;
An article inspection unit for inspecting the article based on the stored inspection image;
Equipped with a,
The article detection unit generates an image for the specific area, compares the previously generated image of the specific area, calculates the amount of change in brightness of pixels at the same position, and the amount of change is Count the number of pixels exceeding a predetermined threshold, and determine the arrival of the article when the number of pixels exceeds a certain number,
Item inspection device. The time calculation unit notifies the time when the article to be conveyed reaches the center position on the image based on the length of the article in the conveyance direction and the conveyance speed of the article by the conveyance unit.
The article inspection apparatus according to claim 1.

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