Image acquisition device, inspection device, and image acquisition method

Abstract

To acquire a good area image free of blurs and distortion.SOLUTION: The present invention comprises: a first conveyance unit for conveying and stopping an object; a second conveyance unit for conveying and stopping the object and installed continuously to the first conveyance unit; a light emission unit for irradiating the object with light while the object is stopped; a light reception unit for receiving heat radiation from the object; a two-dimensional image acquisition unit for acquiring temperature information on the object as a two-dimensional image from the information received by the light reception unit; and a position and inclination restricting unit for restricting the position and inclination of the object in a direction orthogonal to the conveyance direction and installed in the first conveyance unit. The speed at which the object is conveyed by the second conveyance unit is variable from 0 to V, where V represents a speed at which the object is conveyed by the first conveyance unit, and the friction coefficient of the first conveyance unit is smaller than the friction coefficient of the second conveyance unit.SELECTED DRAWING: Figure 14

Description

Technical Field

[0001] The present invention relates to an image acquisition device, an inspection device, and an image acquisition method.

Background Art

[0002] Conventionally, there has been an inspection device for a package in which an article such as food is enclosed in a packaging material and sealed, and which inspects whether or not the sealed portion of the package is properly sealed.

[0003] Patent Document 1 discloses a technique for an inspection device for a package, which constantly illuminates the package during inspection, and captures an image of the illuminated package after a predetermined time has elapsed since detecting the entry of the package to a predetermined point.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, according to the conventional technique, there has been a problem that it is difficult to perform high-precision inspection because blurring occurs due to movement of the package during the exposure time, or distortion occurs in the image due to a readout time difference in the sequential readout method (rolling shutter method).

[0005] The present invention has been made in view of the above, and an object thereof is to obtain a good area image without blurring or distortion.

Means for Solving the Problems

[0006] In order to solve the above-described problems and achieve the object, the present invention provides placed a first transport unit that transports an object, and a second transport unit that is connected to the first transport unit and placed transports the object and and a control unit that controls the speeds at which the first transport unit and the second transport unit transport the object, and the gap between the first transport unit and the second transport unit, or on the second transport unitA light emitting unit that irradiates the object with light in a state where the object is stopped, a light receiving unit that receives thermal radiation from the object, and a two-dimensional image acquisition unit that acquires temperature information of the object as a two-dimensional image from information received by the light receiving unit, and a position inclination regulating unit that is provided in the first transport unit and regulates the position and inclination in a direction orthogonal to the transport direction of the object. The control unit When the speed at which the object is transported in the first transport unit is V, when the object moves from the first transport unit to the second transport unit The speed at which the object is transported in the second transport unit decelerates from V to 0 make it , and the friction coefficient of the first transport unit is smaller than the friction coefficient of the second transport unit.

Advantages of the Invention

[0007] According to the present invention, there is an effect that a good area image without blur or distortion can be acquired.

Brief Description of the Drawings

[0008]

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Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of an image acquisition device, an inspection device, and an image acquisition method will be described in detail with reference to the accompanying drawings.

[0010] Here, FIG. 1 is a schematic diagram showing a configuration example of an inspection apparatus 1 according to the embodiment, and FIG. 2 is a diagram showing an example of a package 50 to be inspected by the inspection apparatus 1. The inspection apparatus 1 inspects whether the package 50, which is an object to be inspected, is properly sealed, and excludes abnormal packages 50 from the production line.

[0011] First, the package 50 will be described.

[0012] As shown in FIG. 2, the package 50 contains an article (for example, food such as curry or soup) inside a bag-shaped packaging material 51. The package 50 shown in FIG. 2 seals the bag-shaped opening by adhering the packaging materials 51 to each other.

[0013] As the packaging material 51 of the package 50, a single-layer plastic film, a single-layer plastic film with surface treatment, or a plastic film obtained by laminating a plurality of them is used. Examples of the surface treatment include coating for imparting moisture resistance and vapor deposition of aluminum, silica, alumina, etc. for imparting gas barrier properties.

[0014] Furthermore, as the packaging material 51 of the package 50, a film obtained by laminating an aluminum foil 51b (see FIG. 3) to the above-described film is used. The packaging material 51 laminated with the aluminum foil 51b is used for applications that require high gas barrier properties and moisture resistance. In particular, the packaging material 51 laminated with the aluminum foil 51b is a packaging container for retort foods and is so-called a retort pouch.

[0015] FIG. 3 is a diagram showing a configuration example of the packaging material 51. The packaging material 51 shown in FIG. 3 shows a configuration example of the packaging material 51 for a retort pouch. The packaging material 51 shown in FIG. 3 is laminated in the order of a polyester (PET) film 51a, an aluminum foil 51b, and an unstretched polypropylene (CPP) film 51c from the surface. Films laminated with an aluminum foil or an aluminum vapor deposition film like the packaging material 51 shown in FIG. 3 have poor transparency by visual inspection, and it is difficult to visually confirm the articles contained inside the packaging material 51.

[0016] In the package 50 shown in FIG. 2, the portion where the packaging materials 51 are adhered to each other to seal the bag-shaped opening is called a seal portion 52. The seal portion 52 is formed by heat sealing by pressing a heated bar against the portion to be sealed, ultrasonic sealing by melting and joining the portion to be sealed by ultrasonic vibration and pressure, or the like.

[0017] Here, the manufacturing process of the package 50 will be briefly described. The package 50 is manufactured by filling a bag-shaped packaging material 51 with articles (for example, foods such as curry and soup) by filling means (filling machine) not shown, and then sealing with the seal portion 52.

[0018] In such a manufacturing process, the inspection device 1 performs a seal inspection on the package 50 sealed with the seal portion 52 to confirm that it is firmly sealed and no leakage of the article occurs. In the seal inspection, it is determined whether the seal portion 52 is in a good state or a defective state. Defective states include, for example, states called biting, pinhole, wrinkle, penetration, etc. Specifically, biting is a defect in which the article is bitten into the seal portion 52, pinhole is a defect in which a hole is open in the seal portion 52, wrinkle is a defect in which folding wrinkles or overlapping wrinkles occur in the seal portion 52, penetration is a defect in which a passage is formed such that the article leaks to the outside through the seal portion 52, and so on.

[0019] Next, the inspection device 1 will be described in detail.

[0020] As shown in FIG. 1, the inspection apparatus 1 includes a conveyance unit 2, an image acquisition device 3, and a control device 4.

[0021] The image acquisition device 3 includes a light emitting unit 31 disposed below the conveyance unit 2 and a light receiving unit 32 disposed above the conveyance unit 2.

[0022] The conveyance unit 2 includes a first conveyance unit 21 and a second conveyance unit 22 connected in series. The first conveyance unit 21 and the second conveyance unit 22 rotate an endless belt to convey the package 50 on the belt. The first conveyance unit 21 is disposed on the upstream side in the conveyance direction X of the package 50 with respect to the arrangement position of the image acquisition device 3. The second conveyance unit 22 is disposed on the downstream side in the conveyance direction X of the package 50 with respect to the arrangement position of the image acquisition device 3. The conveyance unit 2 forms a gap O that is a space between the light emitting unit 31 and the light receiving unit 32 between the first conveyance unit 21 and the second conveyance unit 22. The distance between the first conveyance unit 21 and the second conveyance unit 22, which is the gap O, is a distance that does not affect the transfer from the first conveyance unit 21 to the second conveyance unit 22. With such a configuration, the conveyance unit 2 conveys the package 50 through the space between the light emitting unit 31 and the light receiving unit 32.

[0023] The image acquisition device 3 acquires, as an image, two-dimensional temperature information of the seal portion 52 of the package 50 conveyed by the conveyance unit 2.

[0024] The light emitting unit 31 irradiates the entire seal portion 52 of the package 50 conveyed by the conveyance unit 2 two-dimensionally with light. Note that the light emitting unit 31 may irradiate the package 50 being conveyed by the conveyance unit 2 with light in the gap O between the first conveyance unit 21 and the second conveyance unit 22, or may irradiate the package 50 that has once stopped on the conveyance unit 2 with light.

[0025] Note that, in the present embodiment, light is irradiated when the seal portion 52, which is the rear end of the package 50, is positioned in the gap O between the first conveying unit 21 and the second conveying unit 22. However, the present invention is not limited to this. For example, when the seal portion 52 of the package 50 is near the center of the package 50, light may be irradiated when the seal portion 52 near the center of the package 50 is positioned in the gap O between the first conveying unit 21 and the second conveying unit 22.

[0026] The light receiving unit 32 two-dimensionally receives the thermal radiation from the entire seal portion 52 of the package 50 in response to the light irradiation from the light emitting unit 31.

[0027] Next, the control device 4 will be described. The control device 4 controls the entire inspection device 1. Here, FIG. 4 is a block diagram showing the hardware configuration of the control device 4. As shown in FIG. 4, the control device 4 includes a CPU (Central Processing Unit) 41, a ROM (Read Only Memory) 42, a RAM (Random Access Memory) 43, an HDD 44, and the like. The control device 4 drives and controls each part of the conveying unit 2 and the image acquisition device 3 using the RAM 43 as a work memory according to a program stored in advance in the ROM 42 or the HDD 44. As the control device 4, for example, a personal computer (desktop, notebook personal computer) can be used.

[0028] The program executed by the control device 4 of the present embodiment may be configured to be recorded and provided on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, or a DVD (Digital Versatile Disk) in an installable format or an executable format file.

[0029] Furthermore, the program executed by the control device 4 of the present embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Also, the program executed by the control device 4 of the present embodiment may be configured to be provided or distributed via a network such as the Internet.

[0030] Based on the two-dimensional image captured by the image acquisition device 3, the control device 4 determines whether the seal portion 52 of the package 50 is good or bad.

[0031] Next, the functions of the control device 4 will be described.

[0032] FIG. 5 is a functional block diagram showing the functions of the control device 4. As shown in FIG. 5, the control device 4 functions as a control unit 401, a two-dimensional image acquisition unit 402, and a pass / fail determination unit 403 when the CPU 41 operates according to a program.

[0033] The control unit 401 controls the light emission of the light emitting unit 31 and the light reception of the light receiving unit 32 of the image acquisition device 3. Also, the control unit 401 controls the driving of the first transport unit 21 and the second transport unit 22 of the transport unit 2.

[0034] The two-dimensional image acquisition unit 402 acquires, as an image, the two-dimensional temperature information of the seal portion 52 of the package 50 from the thermal radiation information two-dimensionally received by the light receiving unit 32. That is, the two-dimensional image acquisition unit 402 converts the optical information into temperature information and acquires a temperature image. This is also called thermography (thermal image). Note that the two-dimensional image acquisition unit 402 may be provided in an infrared camera in which the light receiving unit 32 is a non-cooled microbolometer.

[0035] Next, the light emitting unit 31 and the light receiving unit 32 will be described in detail.

[0036] As described above, for the packaging material 51 of the package 50, a film obtained by laminating an aluminum vapor-deposited film or an aluminum foil is used, and at least aluminum is included. Therefore, the light-emitting unit 31 of the inspection apparatus 1 of the present embodiment irradiates, onto one side of the seal portion 52 of the package 50, light having a wavelength that is absorbed by at least aluminum. The aluminum foil 51b (see FIG. 3) of the packaging material 51 absorbs the light irradiated by the light-emitting unit 31 and converts the light energy into heat energy. The heat generated in the aluminum foil 51b of the packaging material 51 is transmitted between the surfaces of the respective layers and within each layer, and reaches the surface of the packaging material 51. Then, the packaging material 51 emits light by thermal radiation from the surface. This light emission is radiated in a spectrum based on the so-called Planck's radiation law and is received by the light-receiving unit 32. The light-receiving unit 32 receives the thermal radiation information two-dimensionally.

[0037] FIG. 6 is a graph showing the absorption rate of aluminum. Aluminum has the absorption spectrum shown in FIG. 6. As shown in FIG. 6, aluminum effectively causes light absorption at the peak of the absorption rate of near-infrared light of 0.78 μm to 1.0 μm. Also, aluminum has a high absorption rate for ultraviolet light (0.38 μm or less) and visible light (0.38 μm to 0.78 μm). Note that the absorption rate of aluminum decreases at wavelengths of 1 μm or more. Therefore, it is desirable that the light-emitting unit 31 irradiates at least any one of ultraviolet light, visible light, and near-infrared light. Therefore, the light-emitting unit 31 of the present embodiment applies a halogen lamp that can irradiate light including at least ultraviolet light, visible light, and near-infrared light. A halogen lamp can generally irradiate light having a wavelength longer than visible light and has a very broad emission spectrum. A halogen lamp depends on the temperature of the lamp, but particularly contains a large amount of light having a wavelength longer than near-infrared light (for example, contains 50% or more).

[0038] Note that the light emitting unit 31 is not limited to a halogen lamp, and a xenon lamp capable of irradiating ultraviolet light, visible light, and near-infrared light may be applied. Generally, a xenon lamp has a broad emission spectrum spanning ultraviolet light, visible light, and near-infrared light, and has a plurality of sharp emission spectra in the near-infrared region. The xenon lamp hardly contains wavelengths longer than near-infrared light (for example, 5% or less). Light with a wavelength longer than near-infrared light is also called heat rays, which can heat the surrounding members, thus affecting the miniaturization of the device and the selection of components. Therefore, it is preferably practical not to contain light with a wavelength longer than near-infrared light.

[0039] Also, the light emitting unit 31 may be applied with a near-infrared LED or a near-infrared laser having a peak wavelength in the near-infrared region. Since the near-infrared LED or the near-infrared laser has a peak of the emission spectrum in almost the same wavelength band as the peak of the absorption spectrum of aluminum, it can convert light energy into heat energy with high efficiency. In addition, the near-infrared LED or the near-infrared laser generally has a longer lifespan than a halogen lamp or a xenon lamp, and has the advantage that the replacement cycle can be extended when used in the continuously operating inspection device 1.

[0040] Furthermore, the light emitting unit 31 may be continuously lit (DC emission) or intermittently lit (pulse emission). However, from the perspective of lifespan, it is preferably intermittently lit at about 1 Hz to 2 Hz. Specifically, lasers, LEDs, and xenon lamps are applicable.

[0041] Furthermore, when the light emitting unit 31 is continuously lit (DC emission), an intermittent irradiation means (shutter) that causes intermittent lighting with respect to the package 50 may be provided between the package 50.

[0042] In this embodiment, the surface temperature rise of the sealing portion 52 may be about several degrees Celsius to 10 degrees Celsius. Although the temperature may be raised further, a high-power light source is required, which is not practical in terms of the cost and size of the light source. Assuming that the ambient temperature of the inspection device 1 is about 20 to 30 degrees Celsius, it will be about 273 degrees Celsius + 20 to 30 degrees Celsius + several degrees Celsius to 10 degrees Celsius = 295 to 315 K. Also, according to Planck's law, it is known that the thermal radiation corresponding to 300 K has a wavelength of about 3 μm or more. Thus, the light radiated by thermal radiation from the sealing portion 52 of the package 50 becomes light with a wavelength of about 3 μm or more according to Planck's law. That is, the light receiving portion 32 receives light having a wavelength of 3 μm or more.

[0043] By making the wavelength of the light irradiated by the light emitting portion 31 different from the wavelength of the thermal radiation received by the light receiving portion 32 in this way, the light of the light emitting portion 31 is not received by the light receiving portion 32 and does not become noise in the light receiving portion 32, so that a good light receiving signal can be obtained.

[0044] In the atmospheric transmission spectrum, there is a wavelength band called the atmospheric window where the atmospheric transmittance is high. When measuring in the atmosphere, it is preferable to use this band. For example, MWIR (Middle Wavelength Infrared Radiation) in the wavelength band of 3 to 6 μm and LWIR (Long Wavelength Infrared Radiation) in the wavelength band of 8 to 14 μm can be mentioned.

[0045] Also, since the thermal radiation spectrum of about 300 K has a peak at about 10 μm, it is preferable to use the LWIR atmospheric window for more sensitive measurement.

[0046] Therefore, in this embodiment, the light receiving portion 32 uses an infrared light receiving element that receives LWIR. Note that there are a high-sensitivity cooled type infrared light receiving element that needs to be cooled to an extremely low temperature and a non-cooled type that can operate at room temperature for the infrared light receiving element. In this embodiment, the light receiving portion 32 uses a non-cooled type infrared light receiving element that is practical and low in cost.

[0047] The light emitting unit 31 may be any of a point light source, a line light source, and an area light source as long as it irradiates the entire sealing part 52 two-dimensionally.

[0048] Next, the signal output of the light receiving unit 32 will be described in detail.

[0049] As described above, the light receiving unit 32 is an area type light receiving element that two-dimensionally receives the thermal radiation from the entire sealing part 52 accompanying light irradiation. Here, FIG. 7 is a diagram showing a configuration example of the light receiving unit 32. As shown in FIG. 7, the light receiving unit 32 has a rectangular shape and includes a large number of pixels. The light receiving unit 32 sets the readout direction for outputting signals from each pixel as the short side direction (the side with fewer pixels). The pixel columns arranged in order in the readout direction are called lines.

[0050] Here, FIG. 8 is a diagram for explaining a general sequential readout method. Generally, a CMOS readout circuit is built in the light receiving unit 32 which is an area type light receiving element. Here, a general sequential readout method will be briefly described. Note that the description is not limited thereto.

[0051] The vertical axis in FIG. 8 indicates each line, and the readout direction is from the first line to the Nth line. The horizontal axis in FIG. 8 is time. Each line has a desired exposure time and readout time. Here, paying attention to the Pth frame shown in FIG. 8, there is an exposure time difference for each line, and it sequentially proceeds to the second line, the third line, ···. When the readout of all N lines is completed, it proceeds to the (P + 1)th frame which is the next frame.

[0052] Here, FIG. 9 is a diagram exemplarily showing a conventional problem. The example shown in FIG. 9 irradiates light at about 10 ms at a time near the center of the P frame (the light is irradiated within the exposure time of the image). As a result, the two-dimensional image of the obtained P frame was an exposure unevenness image with the lower half being bright. That is, since this P frame cannot be used as a good image, the (P - 1) frame must be used as the image before the light irradiation, and the (P + 1) frame must be used as the image after the light irradiation. And when acquiring an image of an object with a time change, it is a problem that one frame is missing.

[0053] As shown in FIG. 9, when irradiating light within the exposure time of the P frame, when looking at each line, lines irradiated with light and lines not irradiated with light are generated within the exposure time, resulting in a so-called exposure unevenness image. Therefore, in the present embodiment, as shown in FIG. 7, the image area acquired as a two-dimensional image in the light receiving unit 32 is limited to a limited area. That is, in the present embodiment, the image area acquired as a two-dimensional image in the light receiving unit 32 is limited in the direction in which it is sequentially read out, and only the lines not irradiated with light within the exposure time are acquired. Although the light receiving unit 32 outputs signals for all lines (all pixels), it is limited as the information acquired by the two-dimensional image acquisition unit 402. Therefore, since the non-limited area will not be acquired as information later, irradiating light within this exposure time will not cause a problem. Note that considering the optical performance of the lens, the central portion of the light receiving unit 32 is preferable as the limited area in the light receiving unit 32.

[0054] Note that the light receiving unit 32 is rectangular as described above, and the readout direction for outputting signals from each pixel is the short side direction (the side with fewer pixels). Further, in the present embodiment, the information received in the readout direction is limited. Therefore, in order to make the spatial resolution of the acquired two-dimensional image as high as possible, it is preferable that the light receiving unit 32 coincides with the short side direction of the seal unit 52.

[0055] FIG. 10 is a diagram showing an example when light is irradiated during the exposure time outside the limited area of the light receiving unit 32. As shown in FIG. 10, when the limited area of the light receiving unit 32 is set to lines 1 to n, the timing of starting the light irradiation can be after the exposure time of the limited area in the P frame ends and before the exposure time of the limited area in the (P + 1) frame starts. At this time, an image before the light is irradiated can be acquired from the limited area in the P frame, and the limited area in the (P + 1) frame can acquire an image after the light is irradiated. Therefore, no frame is wasted, and a good image can be acquired.

[0056] FIG. 11 is a diagram showing another example when light is irradiated during the exposure time outside the limited area of the light receiving unit 32. As shown in FIG. 11, an image before the light is irradiated can be acquired from the limited area in the P frame, and the limited area in the (P + q) frame can also be acquired as an image after the light is irradiated. The acquisition of the image before irradiation and the start of the light irradiation can be completed only in the P frame, and a good image can be acquired without wasting the inspection time.

[0057] Of course, the limited area is not limited to lines 1 to n, and for example, it can be set to lines m to N. Even in this case, similarly, the timing of starting the light irradiation can be after the exposure time of the limited area in the P frame ends and before the exposure time of the limited area in the (P + 1) frame starts.

[0058] Next, the light irradiation time in the light emitting unit 31 will be described in detail.

[0059] FIG. 12 is a diagram showing an example of the time when the light emitting unit 31 irradiates light. As shown in FIG. 12, the light emitting unit 31 sets the light irradiation time for irradiating light to be between after the exposure time of the limited area in the P frame ends and before the exposure time of the limited area in the (P + 1) frame starts.

[0060] FIG. 13 is a diagram showing another example of the time when the light emitting unit 31 irradiates light. As shown in FIG. 13, the light emitting unit 31 may have a light irradiation time for irradiating light from after the exposure time of the limited area in the P frame ends to after the (P + 1) frame and later.

[0061] As described above, when imaging the package 50 being conveyed by the conveyance unit 2 using the light receiving unit 32 that sequentially reads out each line with an exposure time difference, the image will be distorted. Therefore, it is preferable to start irradiating light by the light emitting unit 31 and perform light reception of the P frame and the (P + 1) frame by the light receiving unit 32 while temporarily stopping the package 50 being conveyed by the conveyance unit 2.

[0062] Next, the stop mechanism of the package 50 in the conveyance unit 2 of the inspection device 1 will be described. The conveyance unit 2 can stop the package 50 by being configured as follows.

[0063] The first conveyance unit 21 is controlled by the control unit 401 (see FIG. 5) of the control device 4 and moves the package 50 at a speed V1. The speed V1 is a constant speed V. The second conveyance unit 22 is controlled by the control unit 401 (see FIG. 5) of the control device 4 and moves the package 50 at a speed V2. The speed V2 can be varied from 0 to V. Also, the friction coefficient μ1 of the surface of the belt of the first conveyance unit 21 that conveys the package 50 and the friction coefficient μ2 of the surface of the belt of the second conveyance unit 22 that conveys the package 50 are different from each other and are configured such that μ1 < μ2.

[0064] As shown in FIG. 1, the conveyance unit 2 includes a position and inclination regulating unit 23 in the first conveyance unit 21. Here, FIG. 14 is a diagram exemplarily showing the configuration of the position and inclination regulating unit 23. As a simple example, as shown in FIG. 14, the position and inclination regulating unit 23 is configured by a U-shaped guide mechanism formed of an aluminum material as a simple example.

[0065] The package 50 conveyed on the first conveyor section 21 is conveyed with a certain degree of variation in the position in the direction Y orthogonal to the conveying direction. The position and inclination regulating section 23 is a guide mechanism for regulating the position in the direction Y orthogonal to the conveying direction of the package 50 conveyed on the first conveyor section 21 to a predetermined position. Further, the package 50 conveyed on the first conveyor section 21 is also conveyed with a certain degree of variation in the inclination in the direction Y orthogonal to the conveying direction. The position and inclination regulating section 23 is a guide mechanism for simultaneously regulating the inclination in the direction Y orthogonal to the conveying direction of the package 50 conveyed on the first conveyor section 21. Note that the position and inclination regulating section 23 is not limited to the illustrated form, and existing methods can be used.

[0066] The package 50 is conveyed on the first conveyor section 21 at a constant speed V, and the position and inclination in the direction Y orthogonal to the conveying direction are regulated by the position and inclination regulating section 23. The position and inclination regulating section 23 regulates the package 50 substantially parallel to the conveying direction and the direction Y orthogonal to the conveying direction. Note that the friction coefficient μ1 of the belt of the first conveyor section 21 is set in a state such that the package 50 slides in the direction Y orthogonal to the conveying direction while being conveyed in the conveying direction on the belt of the first conveyor section 21 according to the position and inclination regulating section 23.

[0067] The package 50 whose position and inclination are regulated by the position and inclination regulating section 23 is conveyed from the first conveyor section 21 to the second conveyor section 22. Note that the first conveyor section 21 and the second conveyor section 22 are arranged with a predetermined gap O. When the package 50 moves to the second conveyor section 22, the second conveyor section 22 decelerates from the speed V to 0 and stops. The package 50 stops according to the speed of the second conveyor section 22 with almost no sliding on the belt of the second conveyor section 22. The friction coefficient μ2 of the belt of the second conveyor section 22 is set in a state where sliding due to deceleration is unlikely to occur.

[0068] Therefore, the position inclination regulating unit 23 adjusts the position and inclination state in the direction Y orthogonal to the conveying direction of the package 50, and then decelerates and stops (V→0) the speed of the belt of the second conveying unit 22 with a large friction coefficient, thereby stopping the package 50. By temporarily stopping the package 50 during conveyance in this way and imaging it with the light receiving unit 32 while it is stopped, blurring and image distortion generated during imaging do not occur. Furthermore, the influence of temperature changes due to convection during movement can be reduced.

[0069] Here, the position in the direction Y orthogonal to the conveying direction of the package 50 has already been regulated by the position inclination regulating unit 23. Also, the stop position in the conveying direction of the package 50 can be regulated by controlling the deceleration to stop of the second conveying unit 22. When the package 50 slides on the belt of the second conveying unit 22 by inertia, the control unit 401 (see FIG. 5) of the control device 4 performs deceleration control of the second conveying unit 22 including the sliding amount. Therefore, the conveying unit 2 can place the seal portion 52 within the field of view of the light receiving unit 32 in the conveying direction and the direction Y orthogonal to the conveying direction. When positioning can be performed accurately, there is an advantage that the region of the two-dimensional image acquired as temperature information can be narrowed and the image size can be reduced from the information received by the light receiving unit 32.

[0070] If the package 50 is a substantially rectangular object, a two-dimensional image can be acquired with each side being substantially parallel to the light receiving unit 32. In this case, the process of cutting out a part of the package 50 from the light receiving unit 32 also becomes easy.

[0071] After that, the second conveying unit 22 accelerates from a speed of 0 to V and conveys the package 50 at a constant speed V.

[0072] In addition, as shown in FIG. 1, the conveying unit 2 includes a conveying regulating unit 24 for regulating the conveyance of the package 50 in the conveying direction in the second conveying unit 22. Here, FIG. 15 is a diagram exemplarily showing the configuration of the conveying regulating unit 24. FIG. 15(a) is a top view of the conveying regulating unit 24, and FIG. 15(b) is a side view of the conveying regulating unit 24. As shown in FIG. 15, the conveying regulating unit 24 raises and lowers a plate-like member formed of an aluminum material.

[0073] As described above, when the package 50 moves to the second conveying unit 22, the second conveying unit 22 decelerates from the speed V to 0 and stops. By arranging the conveyance regulation unit 24 and abutting the leading end in the conveyance direction of the package 50, the conveyance unit 2 can accurately position the stop position of the package 50.

[0074] The position in the direction Y orthogonal to the conveyance direction of the package 50 is regulated by the position inclination regulation unit 23, and the inclination is also regulated. Therefore, the substantially rectangular package 50 abuts one side of its leading end against the conveyance regulation unit 24 perpendicular to the conveyance direction and stops almost parallel thereto.

[0075] More specifically, the conveyance regulation unit 24 lowers a plate-like member onto the belt of the second conveying unit 22 in accordance with the timing at which the second conveying unit 22 decelerates and stops under the control of the control unit 401 (see FIG. 5) of the control device 4, and abuts against the belt of the second conveying unit 22. The conveyance regulation unit 24 raises the plate-like member from the belt of the second conveying unit 22 after the light emission by the light emitting unit 31 and the light reception by the light receiving unit 32 are completed under the control of the control unit 401 (see FIG. 5) of the control device 4, and permits the conveyance of the package 50.

[0076] Note that if the package 50 is circular, the conveyance regulation unit 24 can use an arc-shaped stopper mechanism that matches the shape of the package 50. The conveyance regulation unit 24 is not limited to the form shown in FIG. 15, and existing methods can be used.

[0077] In this embodiment, the package 50 is stopped when the seal portion 52, which is the rear end of the package 50, is located in the gap O between the first conveying unit 21 and the second conveying unit 22. However, the present invention is not limited to this. For example, when the seal portion 52 of the package 50 is near the center of the package 50, the package 50 may be stopped when the seal portion 52 near the center of the package 50 is located in the gap O between the first conveying unit 21 and the second conveying unit 22.

[0078] Incidentally, the conveying unit 2 may be provided with a vibration suppressing unit 25 for suppressing vibrations in a direction perpendicular to the belt surface of the second conveying unit 22. Here, FIG. 16 is a diagram exemplarily showing the configuration of the vibration suppressing unit 25. As shown in FIG. 15, the package 50 abutted against the conveying restricting unit 24 may vibrate depending on characteristics such as the speed and material of the package 50. If the time from when the package 50 stops until it is received by light is long, the vibration gradually converges. However, if the time from when the package 50 stops until it is received by light is short, the vibration, i.e., the vertical movement, becomes a movement in the focusing direction of the photographing, leading to deterioration of the acquired image.

[0079] The vibration suppressing unit 25 includes a pressing member having a certain hardness. The vibration suppressing unit 25 moves from above the package 50 downward and presses the package 50.

[0080] More specifically, the vibration suppressing unit 25 lowers the pressing member onto the belt of the second conveying unit 22 at the timing when the second conveying unit 22 decelerates and stops, or at the timing before and after stopping, under the control of the control unit 401 (see FIG. 5) of the control device 4, and presses the package 50. The vibration suppressing unit 25 raises the pressing member from the package 50 after the light emission by the light emitting unit 31 and the light reception by the light receiving unit 32 are completed under the control of the control unit 401 (see FIG. 5) of the control device 4, and allows the conveyance of the package 50. Thereby, it becomes possible to shorten the time for the vibration of the package 50 to converge. Therefore, image deterioration in the focusing direction can be reduced.

[0081] In addition, the conveying unit 2 may be provided with a gap adjusting unit 26 in the first conveying unit 21 for keeping the intervals of the packages 50 sequentially conveyed constant. Here, FIG. 17 is a diagram exemplarily showing the configuration of the gap adjusting unit 26. As shown in FIG. 17, the gap adjusting unit 26 raises and lowers a plate-like member formed of an aluminum material. More specifically, the gap adjusting unit 26 opens and closes the conveying path by raising or lowering the plate-like member at predetermined time intervals under the control of the control unit 401 (see FIG. 5) of the control device 4.

[0082] The conveying unit 2 can stably continue the conveying operations such as the conveying and stopping of the package 50 by discharging the package 50 at a predetermined time interval by means of the interval adjusting unit 26 as described above. When the package 50 is conveyed randomly, the stop control of the inspection device 1 becomes complicated corresponding to the conveying timing. However, if it is conveyed at regular intervals, the stop control of the inspection device 1 can be completed under a fixed condition.

[0083] In addition, by making the conveying speed V of the first conveying unit 21 faster than the conveying speed of the belt conveyor (not shown) in the previous process, it is possible to prevent a plurality of packages 50 from staying in the interval adjusting unit 26.

[0084] Next, an example of the light emission of the light emitting unit 31 will be described.

[0085] FIG. 18 is a diagram showing an example of a point-type light source when irradiating a stopped package 50. As shown in FIG. 18, the point-type light source irradiates the seal portion 52 in a point shape. As shown in FIG. 18, when the light emitting unit 31 irradiates the stopped package 50, the point-type light source is two-dimensionally irradiated through an optical system that two-dimensionally scans the seal portion 52.

[0086] FIG. 19 is a diagram showing an example of a line-type light source when irradiating a stopped package 50. As shown in FIG. 19, the line-type light source irradiates the seal portion 52 in a line shape. The line-type light source may be formed by arranging point-type light sources in one row or multiple rows to form a line type, or may form a line-shaped irradiation pattern through an optical system using point-type light sources. As shown in FIG. 19, when the light emitting unit 31 irradiates the stopped package 50, the seal portion 52 is two-dimensionally irradiated with a line-type light source that is slightly longer than the short-side width of the seal portion 52 through an optical system that one-dimensionally scans the seal portion 52.

[0087] FIG. 20 is a diagram showing an example of an area type light emitting source when irradiating the stationary package 50. As shown in FIG. 20, the area type light emitting source irradiates the seal portion 52 in an area all at once. The area type light emitting source may be formed by arranging point type light emitting sources vertically and horizontally to form an area type, or by arranging line type light emitting sources in multiple rows to form an area type, or by combining these with an optical system to create an area-like irradiation pattern. As shown in FIG. 20, when irradiating the stationary package 50, the light emitting portion 31 irradiates it all at once with the area type light emitting source.

[0088] Next, the light receiving example of the light receiving portion 32 will be described.

[0089] On the other hand, the light receiving portion 32 is an area type light receiving element that two-dimensionally receives the thermal radiation from the entire seal portion 52 accompanying light irradiation. A microbolometer or the like is applied to the area type light receiving element.

[0090] FIG. 21 is a diagram showing an example of an area type light receiving element when receiving the thermal radiation from the stationary package 50. As shown in FIG. 21, when receiving the thermal radiation from the stationary package 50, the light receiving portion 32 receives the seal portion 52 all at once with the area type light receiving element.

[0091] As described above, there are various modes for the light emitting portion 31 that irradiates the entire seal portion 52 with light and the light receiving portion 32 that receives the thermal radiation from the entire seal portion 52. In the present embodiment, the light emitting portion 31 is an area type light emitting source, and the light receiving portion 32 is an area type light receiving element. By combining the area type light emitting source and the area type light receiving element in this way, whether the package 50 is being conveyed or stationary, the entire seal portion 52 can be irradiated and received all at once without being restricted by the conveyance state. Furthermore, for an area type light emitting source formed by arranging point type light emitting sources (specifically LEDs) vertically and horizontally and an area type light receiving element, an optical system that performs one-dimensional or two-dimensional scanning, that is, movable parts are not required, and high-quality images can be obtained without being affected by vibration.

[0092] Next, the positional relationship between the light emitting portion 31 and the light receiving portion 32 will be described in detail.

[0093] As described above, the light receiving unit 32 does not directly receive the light irradiated from the light emitting unit 31 and transmitted through the seal portion 52 of the packaging material 51, nor the light reflected from the seal portion 52. The light receiving unit 32 receives the light emitted by the thermal radiation from the surface of the packaging material 51 due to the light irradiated from the light emitting unit 31. That is, the light emitting unit 31 and the light receiving unit 32 are not restricted by the arrangement based on the light transmission or regular reflection. Therefore, the degree of freedom in the layout of the light emitting unit 31 and the light receiving unit 32 increases.

[0094] FIG. 22 is a diagram showing a first layout example of the light emitting unit 31 and the light receiving unit 32. In the example shown in FIG. 22, the light receiving unit 32 is installed with its optical axis tilted with respect to the seal portion 52 and the light emitting unit 31 of the packaging material 51, which is a plane substantially parallel to the transport direction X. By tilting the optical axis of the light receiving unit 32 in this way with respect to the seal portion 52 of the packaging material 51, it is possible to prevent the reflection of the light receiving unit 32 itself.

[0095] More specifically, as shown in FIG. 22, since the package 50 houses an article inside the packaging material 51, the vicinity of the seal portion 52 of the package 50 has a bulge. Therefore, while the seal portion 52 is substantially parallel to the transport direction X, the vicinity of the seal portion 52 is inclined with respect to the transport direction X. Therefore, in the example shown in FIG. 22, the light receiving unit 32 is installed with its optical axis tilted not in a direction orthogonal to the inclination of the vicinity of the seal portion 52 of the packaging material 51, but in the same direction as the inclination of the vicinity of the seal portion 52 of the packaging material 51.

[0096] Here, FIG. 23 is a diagram showing a second layout example of the light emitting unit 31 and the light receiving unit 32. In the example shown in FIG. 23, on the condition that there is no influence of the reflection of the light receiving unit 32 itself, the light receiving unit 32 may be arranged at a position orthogonal to the seal portion 52, which is a plane substantially parallel to the transport direction X, without being tilted.

[0097] Here, FIG. 24 is a diagram showing a third layout example of the light emitting unit 31 and the light receiving unit 32. In the example shown in FIG. 24, in addition to the second layout example of FIG. 23, the light emitting unit 31 is installed with its optical axis tilted with respect to the seal portion 52 of the packaging material 51, which is a plane substantially parallel to the conveyance direction X, and the light receiving unit 32.

[0098] Finally, the pass / fail determination unit 403 will be described.

[0099] Based on a two-dimensional image having temperature information, the pass / fail determination unit 403 determines whether the seal portion 52 of the package 50 is in a good state or a bad state, that is, determines pass / fail. In order to visualize a bad state, the pass / fail determination unit 403 performs various known image processes on the two-dimensional image.

[0100] As described above, if there is a bad state in the seal portion 52 of the package 50, the heat capacity of the seal portion 52 changes with respect to the good state. For example, bite-in is a defect in which an article is bitten into the seal portion 52, and it is sealed in a state where the article is sandwiched between the packaging materials 51. Therefore, a new layer is formed by the article, and the heat transfer is delayed. Penetration is a defect in which a passage is formed through which an article leaks to the outside in the seal portion 52, and due to the air layer between the packaging materials 51, the heat transfer is delayed due to the high thermal resistance of the air. Thus, if there is a bad state in the seal portion 52 of the package 50, the time for heat to reach the surface of the seal portion 52 is delayed, and thus a temperature distribution is generated on the surface. Therefore, the pass / fail determination unit 403 can determine that it is in a bad state, that is, fail, based on the temperature distribution generated in the two-dimensional image having temperature information.

[0101] Next, the pass / fail determination of the seal portion 52 in the pass / fail determination unit 403 will be described.

[0102] Here, FIG. 25 is a graph showing an example of the change in surface temperature at a good state position and a bad state position, and FIG. 26 is a diagram showing a specific example of a two-dimensional image for determining the quality of the seal portion 52. The example shown in FIG. 26 shows the case where there is an air layer in the seal portion 52 as a bad state. This simulates a situation such as penetration or the biting-in of contents containing air.

[0103] The example shown in FIG. 25 is for the case where there are a good state and a bad state in the seal portion 52 containing aluminum. At time 0, light is irradiated from one side by the light emitting portion 31, and the temperature distribution of the surface on the other side is acquired at a certain time t.

[0104] The two-dimensional image shown in FIG. 26 is the image acquired at time A shown in FIG. 25. The image shown in FIG. 26 is a monochrome image where white indicates a high temperature and black indicates a low temperature. As shown in FIG. 26, it can be seen that the position where the presence of an air layer in the seal portion 52 results in a bad state is darker than the surroundings.

[0105] In the example shown in FIG. 25, the position in the good state reaches the peak temperature at time T. This time varies depending on the type and thickness of the packaging material 51, but is approximately from several 100 ms to less than 1 s. On the other hand, as shown in FIG. 25, the position in the bad state reaches the peak temperature after time T, and the peak temperatures of both the good state and the bad state are almost the same. And from FIG. 25, it can be seen that at 0 < t < T, the temperature is higher in the good state than in the bad state. Note that the good state and the bad state reach almost the same peak temperature as time passes, and the temperature difference becomes small after the peak.

[0106] As described above, when there is an air layer in the seal portion 52 as shown in FIG. 26, it can be seen that the thermal resistance of the seal portion 52 in the portion with the air layer increases, resulting in a delay in the transmission of heat. That is, the temporal change in the surface temperature of the seal portion 52 differs between the good state and the bad state, and a detectable large temperature difference occurs at a certain time. The pass / fail determination unit 403 can detect the bad state by capturing the two-dimensional image at this time.

[0107] However, depending on the bad state, the thermal resistance may decrease and the temperature may rise above the surroundings. Even in such a case, by observing the difference between the good state and the bad state, the bad state of the seal portion 52 can be detected.

[0108] The inspection device 1 determines whether the seal portion 52 of the package 50 is good or bad as described above. Further, after the inspection device 1 conveys the package 50 by the second conveyance unit 22 of the conveyance unit 2, the package 50 determined to be bad is excluded from the second conveyance unit 22 by a sorting means (rejector) not shown. On the other hand, the package 50 determined to be good is conveyed by the second conveyance unit 22 and boxed by a packing means (caser) not shown or manually.

[0109] Thus, according to the present embodiment, the position and inclination state of the package 50 in the direction Y orthogonal to the conveyance direction of the package 50 are adjusted by the position inclination regulating unit 23 (since the friction coefficient of the first conveyance unit 21 is small, the package 50 is regulated while sliding on the first conveyance unit 21 and the state is adjusted. The first conveyance unit 21 is moving at a constant speed), and then the package 50 is stopped by decelerating and stopping the speed of the second conveyance unit 22 having a large friction coefficient. By once stopping the package 50 during conveyance and receiving light by the light receiving unit 32 while it is stopped, blur and image distortion generated during the imaging of the package 50 do not occur. Thereby, a good area image without blur and distortion can be acquired. Further, since a good image can be used, an inspection device capable of performing highly accurate pass / fail determination can be realized.

[0110] Furthermore, in temperature measurement using an infrared camera, even if the package is stationary, temperature changes due to the convection of the surrounding air occur. However, according to the present embodiment, since the influence of temperature changes due to convection can be reduced, the problem that the influence of temperature changes due to convection becomes large when the package moves can be avoided.

[0111] In the present embodiment, the conveying unit 2 is configured to form a gap O, which is the space between the light emitting unit 31 and the light receiving unit 32, between the first conveying unit 21 and the second conveying unit 22. However, the present invention is not limited to this. Here, FIG. 27 is a schematic diagram showing a modified example of the configuration of the inspection apparatus 1. As shown in FIG. 27, the conveying unit 2 of the inspection apparatus 1 may be configured not to form a gap O between the first conveying unit 21 and the second conveying unit 22. In this case, the image acquisition device 3 arranges the light emitting unit 31 and the light receiving unit 32 above the conveying unit 2.

[0112] In the present embodiment, aluminum is applied as the substance that absorbs light energy. However, the present invention is not limited to this, and other metals, resins, etc. can be applied as long as they are substances that absorb light energy and convert light energy into heat energy.

[0113] In the present embodiment, a so-called retort pouch is applied as the packaging material 51 of the package 50. However, the present invention is not limited to this, and it can be applied to various packaging materials 51 that accommodate articles and seal the openings. For example, as the packaging material 51 of the package 50, the lid of a yogurt container, a container for enclosing medicine tablets, etc. can be mentioned.

[0114] Note that the inspection apparatus 1 of this embodiment can be used for in-line inspection. As a production method for mass production, there is a method in which a plurality of products are sequentially conveyed on a belt conveyor and produced through a plurality of processes. Then, in order to sequentially inspect the produced products, an inspection process is incorporated into the belt conveyor. Such inspection is called in-line inspection. In a normal inspection machine, area imaging is performed while transporting the object, whereas the inspection apparatus 1 can perform high-quality imaging because it stops once for area imaging, and the inspection accuracy can be improved. The inspection apparatus 1 is suitable for in-line inspection.

[0115] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the above embodiments are merely examples of the present invention, and the present invention is not limited only to the configurations of the above embodiments. Even if there are design changes and the like within the scope not departing from the gist of the present invention, they are included in the present invention.

Explanation of Reference Numerals

[0116] 1 Inspection apparatus, Image acquisition apparatus 21 First conveyance unit 22 Second conveyance unit 23 Position and inclination regulation unit 24 Conveyance regulation unit 25 Vibration suppression unit 26 Spacing adjustment unit 31 Light emission unit 32 Light reception unit 50 Object 402 Two-dimensional image acquisition unit 403 Pass / fail determination unit

Prior Art Documents

Patent Documents

[0117]

Patent Document 1

Claims

Claim 1: A first conveying unit configured to convey an object placed thereon, a second conveying unit connected to the first conveying unit and configured to convey the object placed thereon, a control unit configured to control the speeds at which the first conveying unit and the second conveying unit convey the object, a light emitting unit configured to irradiate the object with light when the object is stopped in the gap between the first conveying unit and the second conveying unit or on the second conveying unit, a light receiving unit configured to receive heat radiation from the object, a two-dimensional image acquisition unit configured to acquire temperature information of the object as a two-dimensional image from information received by the light receiving unit, a position and inclination regulation unit provided in the first conveying unit and configured to regulate the position and inclination of the object in a direction orthogonal to the conveying direction of the object, characterized by comprising: When the speed at which the control unit conveys the object in the first conveying unit is V, when the object moves from the first conveying unit to the second conveying unit, the control unit decelerates the speed at which the object is conveyed in the second conveying unit from V to 0. The friction coefficient of the first conveying unit is smaller than the friction coefficient of the second conveying unit. An image acquisition device characterized by the above. Claim 2 The first conveying unit and the second conveying unit are connected in series with a predetermined gap provided in the conveying direction, and a part of the object stops above the gap. The image acquisition device according to claim 1, characterized by the above. Claim 3 The light emitting unit irradiates light through the gap when the object is stopped. The image acquisition device according to claim 2, characterized by the above. Claim 4 The light receiving unit receives heat radiation through the gap when the object is stopped. The image acquisition device according to claim 2, characterized by the above. Claim 5 The second conveying unit includes a conveying regulation unit configured to regulate the conveyance of the object in the conveying direction of the object. The image acquisition device according to any one of claims 1 to 4, characterized by the above. Claim 6 The second conveying unit includes a vibration suppression unit configured to suppress vibration of the object. The image acquisition device according to claim 5, characterized by the above. Claim 7 The first conveying unit includes a gap adjustment unit configured to keep the intervals between the objects conveyed sequentially constant. The image acquisition device according to any one of claims 1 to 6, characterized by the above. Claim 8 An image acquisition device according to any one of claims 1 to 7, and a pass / fail determination unit configured to determine the pass / fail of an object from a two-dimensional image acquired by the image acquisition device. An inspection device characterized by comprising the above. Claim 9 The object is a package including a sealed portion where at least a part of the packaging material is sealed. The pass / fail determination unit determines the pass / fail of the sealed portion of the package. The inspection device according to claim 8, characterized in that.

10. A first conveyance unit includes a first conveyance step of conveying the placed object, subsequent to the first conveyance step, a second conveyance unit includes a second conveyance step of conveying the placed object, a control step of controlling the speeds at which the first conveyance unit and the second conveyance unit convey the object, a light emission step of irradiating the object with light in a state where the object is stopped on the second conveyance unit or in a gap between the first conveyance unit and the second conveyance unit, a light reception step of receiving thermal radiation from the object, a two-dimensional image acquisition step of acquiring temperature information of the object as a two-dimensional image from the information received in the light reception step, a position and inclination regulation step for regulating the position and inclination in a direction orthogonal to the conveyance direction of the object in the first conveyance step, including in the control step, when the speed of conveying the object in the first conveyance step is V, when the object moves from the first conveyance unit to the second conveyance unit, the speed of conveying the object in the second conveyance step is decelerated from V to 0, the friction coefficient of the belt for conveying the object in the first conveyance step is smaller than the friction coefficient of the belt for conveying the object in the second conveyance step, An image acquisition method, characterized in that.

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