Image acquisition device, inspection device, and image acquisition method

Abstract

To suitably acquire frames before and after irradiation of light, without wasting frames.SOLUTION: The present invention comprises a light emission unit for irradiating an object with light at a prescribed timing; a light reception unit for two-dimensionally receiving heat radiation from the object; and a two-dimensional image acquisition unit for acquiring temperature information on the object as a two-dimensional image from information on a limited region out of the information received by the light reception unit, which is limited to a direction in which sequential read-out is performed from the light reception unit. The timing at which the light emission unit initiates irradiation of light is after an exposure time for the limited region of the P-th frame is finished and before an exposure time for the limited region of the (P+1)-th frame begins. The secondary image acquisition unit acquires information on the limited region of least two frames that include the P-th frame and the (P+q)-th frame (q≥1).SELECTED DRAWING: Figure 7

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 the inspection device inspects whether the seal portion of the package is properly sealed.

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

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conventional inspection device, there is an exposure time difference for each line, and imaging is performed using an area light receiving unit that sequentially reads each line. However, according to an inspection device using such an area light receiving unit, when strong light with a short emission time such as a flash enters during the exposure time of some lines, the area of some lines where the strong light with a short emission time enters becomes brighter than the areas of other lines (exposure unevenness), which is a problem. Also, when the package as the subject is moving, there is a problem that the image is distorted.

[0005] On the other hand, in order to improve the inspection accuracy, there is a method of capturing images in a state where light is not irradiated and in a state where light is irradiated, and performing inspection based on the comparison result. However, according to this method, there is a problem that it is necessary to devise the control of the timing of irradiating light and the timing of capturing images according to the light emitting unit and light receiving unit used (especially when the light emitting unit and light receiving unit are commercially available products).

[0006] The present invention has been made in view of the above, and an object thereof is to favorably acquire frames before and after irradiating light without wasting frames.

Means for Solving the Problem

[0007] In order to solve the above-described problems and achieve the object, the present invention includes a light-emitting unit that irradiates an object with light at a predetermined timing, having a plurality of pixel columns arranged in the readout direction, a light-receiving unit that two-dimensionally receives thermal radiation from the object wherein each of the plurality of pixel columns starts exposure and outputs a signal in the order arranged in the readout direction, the light receiving unit and, from the signals output from a pixel column group composed of a part of the pixel columns arranged continuously among the plurality of pixel columns, a two-dimensional image acquisition unit that acquires temperature information of the object as a two-dimensional image. the process in which each of the plurality of pixel columns starts exposure and outputs a signal in the order arranged in the readout direction is repeatedly performed, The timing at which the light-emitting unit starts irradiating light is after the exposure time of P the last pixel column of the pixel column group in the n-th time of the process ends and before the exposure time of (P + 1) the last pixel column of the pixel column group in the n-th time of the process starts. The two-dimensional image acquisition unit at least, acquires P the information output from the pixel column group in the n-th time of the process and, (P + q) n frames (q ≧ 1) the information output from the pixel column group in the process This is the gist of the present invention.

Advantages of the Invention

[0008] According to the present invention, there is an effect that frames before and after irradiating light can be favorably acquired without wasting frames.

Brief Description of the Drawings

[0009]

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DETAILED DESCRIPTION OF THE INVENTION

[0010] With reference to the accompanying drawings, embodiments of an image acquisition device, an inspection device, and an image acquisition method will be described in detail below.

[0011] Here, FIG. 1 is a schematic diagram showing a configuration example of an inspection device 1 according to an embodiment, and FIG. 2 is a diagram showing an example of a package 50 inspected by the inspection device 1. The inspection device 1 functions as an image acquisition device. The inspection device 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.

[0012] First, the package 50 will be described.

[0013] 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.

[0014] 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 formed by laminating a plurality of them is used. Surface treatments include coating for imparting moisture resistance and vapor deposition of aluminum, silica, alumina, etc. for imparting gas barrier properties.

[0015] 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-mentioned 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.

[0016] 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. A film laminated with an aluminum foil or an aluminum vapor deposition film like the packaging material 51 shown in FIG. 3 has poor transparency by visual inspection, and it is difficult to visually confirm the articles housed inside the packaging material 51.

[0017] 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 the 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.

[0018] 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.

[0019] 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, pinholes, wrinkles, penetration, etc. Specifically, biting is a defect in which the article is bitten into the seal portion 52, a pinhole is a defect in which a hole is opened in the seal portion 52, a 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 through which the article leaks to the outside in the seal portion 52, and so on.

[0020] Next, the inspection device 1 will be described in detail.

[0021] As shown in FIG. 1, the inspection apparatus 1 includes a conveyance unit 2, an image acquisition device 3, and a control device 4.

[0022] 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.

[0023] The conveyance unit 2 includes a first conveyance unit 21 and a second conveyance unit 22. The first conveyance unit 21 and the second conveyance unit 22 convey the package 50 on the belt by rotationally driving an endless belt. The first conveyance unit 21 is disposed upstream of the image acquisition device 3 in the conveyance direction X of the package 50. The second conveyance unit 22 is disposed downstream of the image acquisition device 3 in the conveyance direction X of the package 50. 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 into the space between the light emitting unit 31 and the light receiving unit 32.

[0024] 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.

[0025] The light emitting unit 31 irradiates light two-dimensionally onto the entire seal portion 52 of the package 50 conveyed by the conveyance unit 2. Note that the light emitting unit 31 may irradiate light onto the package 50 being conveyed by the conveyance unit 2 in the gap O between the first conveyance unit 21 and the second conveyance unit 22, or may irradiate light onto the package 50 that has temporarily stopped on the conveyance unit 2.

[0026] The light receiving unit 32 two-dimensionally receives 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 41 (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 conveyance unit 2 and the image acquisition device 3 by using the RAM 43 as a work memory according to programs pre-stored in the ROM 42 and 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, a DVD (Digital Versatile Disk), etc. 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 configured to 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] The control device 4 determines whether the seal portion 52 of the package 50 is good or bad based on the two-dimensional image taken by the image acquisition device 3.

[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. Further, 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, two-dimensional temperature information of the seal portion 52 of the package 50 from the thermal radiation information received two-dimensionally by the light receiving unit 32. That is, the two-dimensional image acquisition unit 402 converts the light 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 in which an aluminum vapor deposition film or an aluminum foil is laminated is used, and at least aluminum is included. Therefore, the light emitting unit 31 of the inspection device 1 of the present embodiment irradiates light having a wavelength at which at least aluminum absorbs light on one side of the seal portion 52 of the package 50. 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] Figure 6 is a graph showing the absorption rate of aluminum. Aluminum has an absorption spectrum as shown in Figure 6. As shown in Figure 6, aluminum effectively causes light absorption at the peak of the absorption rate of near-infrared light from 0.78 μm to 1.0 μm. Also, aluminum has a high absorption rate in 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 for the light-emitting unit 31 to irradiate at least one of ultraviolet light, visible light, and near-infrared light. Thus, 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 with 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 lot of light having a wavelength longer than near-infrared light (for example, 50% or more).

[0038] Note that the light-emitting unit 31 is not limited to a halogen lamp, and a xenon lamp that can irradiate ultraviolet light, visible light, and near-infrared light may be applied. Generally, a xenon lamp has a broad emission spectrum across ultraviolet light, visible light, and near-infrared light and has a plurality of sharp emission spectra in the near-infrared region. A xenon lamp hardly contains light having a wavelength longer than near-infrared light (for example, 5% or less). Such light having a wavelength longer than near-infrared light is also called heat rays and warms surrounding members, thus affecting the miniaturization of the device and the selection of components. Therefore, it is practically preferable not to contain light having a wavelength longer than near-infrared light.

[0039] Further, the light emitting unit 31 may be an infrared LED or an infrared laser having a peak wavelength in the near-infrared range. Since the infrared LED or the infrared laser has a peak in the emission spectrum in a wavelength band substantially the same as the peak of the absorption spectrum of aluminum, light energy can be efficiently converted into heat energy. In addition, infrared LEDs or infrared lasers generally have a longer lifespan than halogen lamps or xenon lamps, and have the advantage that the replacement cycle can be extended when used in the continuously operating inspection apparatus 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 possible to intermittently light 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 light emitting unit 31 and the package 50.

[0042] In this embodiment, the surface temperature rise of the seal 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 apparatus 1 is about 20 to 30 degrees Celsius, then 273°C + 20 to 30°C + several degrees Celsius to 10°C = about 295 to 315 K. Also, it is known that the thermal radiation corresponding to 300 K has a wavelength of about 3 μm or more according to Planck's law. As a result, the light radiated by thermal radiation from the seal portion 52 of the package 50 becomes light having a wavelength of about 3 μm or more according to Planck's law. That is, the light receiving unit 32 receives light having a wavelength of 3 μm or more.

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

[0044] The atmospheric transmission spectrum has 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 at about 300K has a peak at about 10 μm, it is preferable to use the LWIR atmospheric window for more sensitive measurement.

[0046] Therefore, in the present embodiment, the light receiving unit 32 uses an infrared light receiving element that receives LWIR. Note that the infrared light receiving element has a highly sensitive cooled type that needs to be cooled to extremely low temperatures and a non-cooled type that can operate at room temperature. In the present embodiment, the light receiving unit 32 uses a non-cooled infrared light receiving element that is practically low-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 seal portion 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 light receiving element that two-dimensionally receives the thermal radiation from the entire seal portion 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 has the short side direction (the side with fewer pixels) as the readout direction for signal output from each pixel. 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 into the light-receiving unit 32, which is an area-type light-receiving element. Here, a general sequential readout method will be briefly explained. Note that this is not limited to the description.

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

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

[0053] As shown in FIG. 9, when light is irradiated within the exposure time of the P-frame, when viewed line by 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 as 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 is not 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). Furthermore, 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 within 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 lines 1 to n, the timing of starting to irradiate light can be after the exposure time of the limited area of the P-frame ends and before the exposure time of the limited area of the (P + 1)-th frame starts. At this time, an image before irradiating light can be acquired from the limited area of the P-frame, and the limited area of the (P + 1)-th frame can acquire an image after irradiating light. 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 light irradiation can be acquired from the limited area of the P-th frame, and the limited area of the (P + q)-th frame can also be acquired as an image after light irradiation. It is possible to complete the acquisition of the image before irradiation and the start of light irradiation only in the P-th frame, and to acquire a good image without wasting the inspection time.

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

[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 the light irradiation by the light emitting unit 31 and receive light of the P-th frame and the (P + 1)-th 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 transport unit 2 of the inspection apparatus 1 will be described. The transport unit 2 can stop the package 50 by adopting the following configuration.

[0063] The first transport section 21 is controlled by the control section 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 transport section 22 is controlled by the control section 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 coefficient of friction μ1 of the surface of the belt of the first transport section 21 that transports the package 50 and the coefficient of friction μ2 of the surface of the belt of the second transport section 22 that transports the package 50 are different from each other and are configured such that μ1 < μ2.

[0064] As shown in FIG. 1, the transport unit 2 includes a position and inclination regulating section 23 in the first transport section 21. The position and inclination regulating section 23 is configured, as a simple example, by a guide mechanism made of an aluminum material. The package 50 transported on the first transport section 21 is transported with a certain degree of variation in the position in the direction orthogonal to the transport direction. The position and inclination regulating section 23 is a guide mechanism for regulating the position in the direction orthogonal to the transport direction of the package 50 transported on the first transport section 21 to a predetermined position. Also, the package 50 transported on the first transport section 21 is transported with a similar degree of variation in the inclination in the direction orthogonal to the transport direction. The position and inclination regulating section 23 is a guide mechanism for regulating the inclination in the direction orthogonal to the transport direction of the package 50 transported on the first transport section 21. Note that the position and inclination regulating section 23 is not limited to the illustrated form, and existing methods can be used.

[0065] The package 50 is conveyed by the first conveying unit 21 at a constant speed V, and the position and inclination in the direction orthogonal to the conveying direction are regulated by the position and inclination regulating unit 23. The position and inclination regulating unit 23 regulates the package 50 substantially parallel to the conveying direction and the direction orthogonal to the conveying direction. Note that the friction coefficient μ1 of the belt of the first conveying unit 21 is set in a state such that the package 50 slides in the direction orthogonal to the conveying direction while being conveyed in the conveying direction on the belt of the first conveying unit 21 according to the position and inclination regulating unit 23.

[0066] The package 50 whose position and inclination are regulated by the position and inclination regulating unit 23 is conveyed from the first conveying unit 21 to the second conveying unit 22. Note that the first conveying unit 21 and the second conveying unit 22 are arranged with a predetermined gap O. 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. The package 50 stops according to the speed of the second conveying unit 22 with almost no sliding on the belt of the second conveying unit 22. The friction coefficient μ2 of the belt of the second conveying unit 22 is set in a state where sliding due to deceleration is unlikely to occur.

[0067] Therefore, the position and inclination state of the package 50 in the direction orthogonal to the conveying direction are adjusted by the position and inclination regulating unit 23, and then the speed of the belt of the second conveying unit 22 with a large friction coefficient is decelerated and stopped (V→0), thereby stopping the package 50. By once stopping the package 50 during conveyance in this way and imaging with the light receiving unit 32 while it is stopped, blurring and image distortion that occur during imaging do not occur. Furthermore, the influence of temperature change due to convection during movement can be reduced.

[0068] Here, the position in the direction orthogonal to the conveyance direction of the package 50 has already been regulated by the position inclination regulating unit 23. Also, the stop position of the package 50 in the conveyance direction can be regulated by controlling the deceleration to stop of the second conveyance unit 22. When the package 50 slides on the belt of the second conveyance unit 22 by inertia, the control unit 401 (see FIG. 5) of the control device 4 performs deceleration control of the second conveyance unit 22 including the amount of the slide. Therefore, the conveyance unit 2 can place the seal portion 52 within the field of view of the light receiving unit 32 in the conveyance direction and the direction orthogonal to the conveyance direction. When the positioning can be performed accurately, there is an advantage that the region of the two-dimensional image acquired as temperature information can be narrowed down and the image size can be reduced from the information received by the light receiving unit 32.

[0069] In addition, if the package 50 is an object having a substantially rectangular shape, a two-dimensional image can be acquired in a state where each side is 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.

[0070] After that, the second conveyance unit 22 accelerates from a speed of 0 to V and conveys the package 50 at a constant speed V.

[0071] As shown in FIG. 1, the conveyance unit 2 may be provided with a conveyance regulating unit 24 for regulating the conveyance of the package 50 in the conveyance direction in the second conveyance unit 22. As described above, when the package 50 moves to the second conveyance unit 22, the second conveyance unit 22 decelerates from the speed V to 0 and stops. By disposing the conveyance regulating 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.

[0072] As a simple example, the conveyance regulating unit 24 is configured by a stopper mechanism made of an aluminum material. Since the position in the direction orthogonal to the conveyance direction of the package 50 and the inclination are regulated by the position inclination regulating unit 23, the substantially rectangular package 50 abuts against the conveyance regulating unit 24 perpendicular to the conveyance direction with one side of its leading end substantially parallel and stops.

[0073] More specifically, the conveyance control unit 24, under the control of the control unit 401 (see FIG. 5) of the control device 4, lowers a plate-shaped member onto the belt of the second conveyance unit 22 in accordance with the timing at which the second conveyance unit 22 decelerates and stops, and abuts against the belt of the second conveyance unit 22. The conveyance control unit 24, under the control of the control unit 401 (see FIG. 5) of the control device 4, raises the plate-shaped member from the belt of the second conveyance unit 22 after the light emission by the light emitting unit 31 and the light reception by the light receiving unit 32 are completed, and permits the conveyance of the package 50.

[0074] In addition, if the package 50 is circular, the conveyance control unit 24 can use an arc-shaped stopper mechanism that conforms to the shape of the package 50. The conveyance control unit 24 is not limited to the illustrated form, and existing methods can be used.

[0075] Next, an example of the light emission of the light emitting unit 31 will be described.

[0076] FIG. 14 is a diagram showing an example of a point-type light source when irradiating a stationary package 50. As shown in FIG. 14, the point-type light source irradiates the seal portion 52 in a point shape. As shown in FIG. 14, when irradiating a stationary package 50, the light emitting unit 31 two-dimensionally irradiates the point-type light source through an optical system that two-dimensionally scans the seal portion 52.

[0077] FIG. 15 is a diagram showing an example of a line-type light source when irradiating a stationary package 50. As shown in FIG. 15, 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 in a line, or may form a line-shaped irradiation pattern through an optical system using point-type light sources. As shown in FIG. 15, when irradiating a stationary package 50, the light emitting unit 31 two-dimensionally irradiates 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.

[0078] FIG. 16 is a diagram showing an example of an area type light emitting source when irradiating a stationary package 50. As shown in FIG. 16, the area type light emitting source irradiates the seal part 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. 16, when irradiating the stationary package 50, the light emitting part 31 irradiates it all at once with the area type light emitting source.

[0079] Next, an example of the light reception of the light receiving part 32 will be described.

[0080] On the other hand, the light receiving part 32 is an area type light receiving element that two-dimensionally receives the thermal radiation from the entire seal part 52 accompanying light irradiation. A microbolometer or the like is applied to the area type light receiving element.

[0081] FIG. 17 is a diagram showing an example of an area type light receiving element when receiving the thermal radiation from a stationary package 50. As shown in FIG. 17, when receiving the thermal radiation from the stationary package 50, the light receiving part 32 receives the seal part 52 all at once with the area type light receiving element.

[0082] As described above, there are various modes for the light emitting part 31 that irradiates the entire seal part 52 with light and the light receiving part 32 that receives the thermal radiation from the entire seal part 52. In this embodiment, the light emitting part 31 is an area type light emitting source, and the light receiving part 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 stopped, it is possible to irradiate and receive the entire seal part 52 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 scans one-dimensionally or two-dimensionally, that is, movable parts are not required, and high-quality images can be obtained without being affected by vibration.

[0083] Next, the positional relationship between the light emitting part 31 and the light receiving part 32 will be described in detail.

[0084] 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.

[0085] FIG. 18 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. 18, the light receiving unit 32 is installed with its optical axis tilted with respect to the seal portion 52 of the packaging material 51 and the light emitting unit 31, 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.

[0086] More specifically, as shown in FIG. 18, since the package 50 accommodates 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. 18, the light receiving unit 32 is installed with its optical axis inclined not at an inclination 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.

[0087] Here, FIG. 19 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. 19, 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.

[0088] Here, FIG. 20 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. 20, in addition to the second layout example of FIG. 19, 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.

[0089] Finally, the pass / fail determination unit 403 will be described.

[0090] 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.

[0091] 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 becomes slower. 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 presence of an air layer between the packaging materials 51, the heat transfer becomes slower 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, a fail, based on the temperature distribution generated in the two-dimensional image having temperature information.

[0092] Next, the pass / fail determination of the seal portion 52 in the pass / fail determination unit 403 will be described.

[0093] Here, FIG. 21 is a graph showing an example of the change in surface temperature at the position in a good state and the position in a bad state, and FIG. 22 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. 22 shows the case where there is an air layer in the seal portion 52 as a bad state. This simulates the situation seen in penetration or the biting-in of contents containing air.

[0094] The example shown in FIG. 21 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 on the surface of the other side is acquired at a certain time t.

[0095] The two-dimensional image shown in FIG. 22 is the image acquired at time A shown in FIG. 21. The image shown in FIG. 22 is a monochrome image where white indicates a high temperature and black indicates a low temperature. As shown in FIG. 22, 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 compared to the surroundings.

[0096] In the example shown in FIG. 21, 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. 21, 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. 21, 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 smaller after the peak.

[0097] As described above, when there is an air layer in the seal portion 52 as shown in FIG. 22, 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 large detectable 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.

[0098] 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.

[0099] 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.

[0100] Thus, according to the present embodiment, a limited area is defined in the direction in which the light receiving unit 32 sequentially reads out, and the timing at which the light emitting unit 31 starts irradiating light is after the exposure time of the limited area of the P-th frame ends and before the exposure time of the limited area of the (P + 1)-th frame starts. Thereby, since light irradiation is not started within the exposure time of the limited area, the frames before and after light irradiation can be acquired well without wasting the frame. Furthermore, since a good image can be used, an inspection device capable of performing highly accurate pass / fail determination can be realized.

[0101] 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.

[0102] In addition, in this embodiment, a so-called retort pouch is applied as the packaging material 51 of the package 50, but the present invention is not limited to this, and it is applicable to various packaging materials 51 that accommodate articles and seal the openings. For example, as the packaging material 51 of the package 50, a lid of a yogurt container, a container for enclosing a medicine tablet, etc. can be mentioned.

[0103] Note that the inspection device 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. And, in order to sequentially inspect the produced products, an inspection process is incorporated into the belt conveyor. Such inspection is called in-line inspection. While a normal inspection machine performs area imaging while conveying the object, the inspection device 1 can perform high-quality imaging because it stops once for area imaging, and the inspection accuracy can be improved. The inspection device 1 is suitable for in-line inspection.

[0104] 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, etc. within the scope not departing from the gist of the present invention, they are included in the present invention.

Explanation of Reference Numerals

[0105] 1 Inspection device, image acquisition device 21 First conveyance unit 22 Second conveyance 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

[0106]

Patent Document 1

Claims

1. A light emitting unit that irradiates an object with light at a predetermined timing, A light receiving unit having a plurality of pixel columns arranged in a reading direction, for two-dimensionally receiving thermal radiation from the object, wherein each of the plurality of pixel columns starts exposure and outputs a signal in the order in which they are arranged in the reading direction, the light receiving unit; A two-dimensional image acquisition unit that acquires temperature information of the object as a two-dimensional image from signals output from a pixel column group composed of a part of the pixel columns that are continuously arranged among the plurality of pixel columns; Comprising, The process in which each of the plurality of pixel columns starts exposure and outputs a signal in the order in which they are arranged in the reading direction is repeatedly performed, The timing at which the light emitting unit starts irradiating light is after the exposure time of the last pixel column of the pixel column group ends in the P-th process and before the exposure time of the last pixel column of the pixel column group starts in the (P + 1)-th process, The two-dimensional image acquisition unit acquires at least information output from the pixel column group in the P-th process and information output from the pixel column group in the (P + q)-th process (q ≧ 1), An image acquisition device characterized by the above.

2. The two-dimensional image acquisition unit acquires information output from the pixel column group in the P-th process and information output from the pixel column group in the (P + 1)-th process, The image acquisition device according to claim 1, characterized by the above.

3. The process is performed a plurality of times while the object is in a stopped state, The two-dimensional image acquisition unit acquires the two-dimensional image based on information output from the pixel column group in each of the plurality of times of the process, The image acquisition device according to claim 1 or 2, characterized by the above.

4. The pixel column group does not include the first and last pixel columns among the plurality of pixel columns, The image acquisition device according to any one of claims 1 to 3, characterized by the above.

5. An image acquisition device according to any one of claims 1 to 4, A pass / fail determination unit that determines 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.

6. 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 5, characterized by the above.

7. A light emitting step of irradiating an object with light at a predetermined timing, A light receiving step of having a plurality of pixel columns arranged in a reading direction and two-dimensionally receiving thermal radiation from the object by a light receiving unit, wherein each of the plurality of pixel columns starts exposure and outputs a signal in the order arranged in the reading direction, the light receiving step; A two-dimensional image acquisition step of acquiring temperature information of the object as a two-dimensional image from signals output from a pixel column group composed of a part of continuously arranged pixel columns among the plurality of pixel columns; including; The process in which each of the plurality of pixel columns starts exposure and outputs a signal in the order arranged in the reading direction is repeatedly performed; The timing of starting light irradiation in the light emitting step is after the exposure time of the last pixel column of the pixel column group in the P-th process ends and before the exposure time of the last pixel column of the pixel column group in the (P + 1)-th process starts; The two-dimensional image acquisition step acquires at least information output from the pixel column group in the P-th process and information output from the pixel column group in the (P + q)-th process (q ≧ 1); An image acquisition method characterized by the above.

Images