JP2019216400A - Imaging apparatus and imaging method - Google Patents

Abstract

To provide an imaging apparatus and an imaging method, capable of stably imaging an imaging target by preventing contamination of an imaging field of view by contaminants even in an environment where contaminants such as powders and particles exist.SOLUTION: The imaging apparatus includes: a lens; and a photoelectric conversion unit for converting light condensed by the lens into an electric signal. At least the lens of the imaging apparatus is housed in a housing. The housing has: a penetrating light receiving window that allows light to enter at least a part of a light receiving surface in a portion opposite to the light receiving surface of the lens; and a gas inlet at a portion that does not block light from entering the light receiving window. The imaging apparatus is configured to image while discharging the gas supplied into the housing through the gas inlet. Further, the imaging method includes imaging using the imaging apparatus having the above configuration.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging device and an imaging method.

  Various proposals have been made with respect to imaging devices in order to prevent contaminants such as dust and dust from adhering to the imaging unit. For example, in Patent Document 1, in a dustproof device in which a television camera is housed in a dustproof case that is kept airtight, an injection is performed that injects pressurized air supplied into the dustproof case toward a transparent body that forms the front surface of the dustproof case. It is disclosed to form a mouth. Patent Document 2 discloses a camera module structure that includes a cover that covers an imaging element and has an opening corresponding to a predetermined region of a lens, and a window that is provided integrally with the cover. . The document also describes that a light-shielding portion may be provided on the window portion.

Japanese Utility Model Publication No. 56-85460 JP 2008-283247 A

  By the way, in the production process of a product, when an object to be scattered such as a powder or the like is contained in the product by spraying, it is necessary to accurately image the powder or the like to be scattered and periodically check the scattered state. This is important in terms of product quality and performance stability. However, the dustproof device described in Patent Literature 1 injects pressurized air to the front of the dustproof case. Therefore, when imaging a powdery material or the like having high adhesiveness, the powdery material or the like scattered at the time of spraying is dustproof case. Is easily attached to the front surface of the camera, and as a result, the imaging unit is contaminated and the imaging accuracy is reduced. Further, the camera module structure described in Patent Literature 2 is not a technique for capturing an image of a scattered powder or the like.

  Therefore, an object of the present invention is to provide an imaging device that can solve the problems of the related art.

The present invention is an imaging device including a lens and a photoelectric conversion unit that converts light collected by the lens into an electric signal,
At least the lens of the imaging device is housed in a housing,
The housing has a penetrating light-receiving window that allows light to enter at least a part of the light-receiving surface at a portion facing the light-receiving surface of the lens, and blocks light from entering the light-receiving window. Has a gas inlet in a non-
It is an object of the present invention to provide an image pickup apparatus configured to take an image of a gas supplied into the housing through the gas inlet while discharging the gas through the light receiving window.

Further, the present invention is an imaging method for imaging a powder moving in the air by an imaging device including a lens and a photoelectric conversion unit that converts light collected by the lens into an electric signal,
At least the lens of the imaging device is housed in a housing,
The housing has a penetrating light-receiving window that allows light to enter at least a part of the light-receiving surface at a portion facing the light-receiving surface of the lens, and blocks light from entering the light-receiving window. Has a gas inlet in a non-
It is an object of the present invention to provide an imaging method for imaging the gas supplied into the housing through the gas inlet while discharging the gas through the light receiving window.

  Advantageous Effects of Invention According to the present invention, even in an environment where a contaminant material such as a granular material is present, it is possible to prevent the contamination of the imaging visual field by the contaminant material and to stably image the imaging target.

FIG. 1 is a schematic diagram showing an embodiment of the imaging device of the present invention. 2A is an enlarged cross-sectional view (corresponding to FIG. 1) of the imaging device of the present invention, and FIG. 2B is a schematic front view of the imaging device of the present invention viewed from the light receiving window side. 2 (c) is an enlarged schematic diagram of FIG. 2 (a). FIG. 3A is a graph showing the change over time in the number of pixels in the example, and FIG. 3B is a graph showing the change over time in the number of pixels in the comparative example.

  Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings. FIG. 1 shows an embodiment of the imaging apparatus of the present invention. As shown in FIG. 1, the imaging apparatus 10 includes a lens 11 and a photoelectric conversion unit 12 that converts light collected by the lens 11 into an electric signal. The light receiving surface 11S, which is the outer surface of the lens, is disposed so as to face the illumination unit 20 that illuminates a predetermined imaging region, and the imaging target 30 can be moved between the lens 11 and the illumination unit 20. Are located. In the figure, the imaging target 30 falls from the flat plate 31 to between the lens 11 and the illumination unit 20.

  The imaging apparatus 10 used in the present invention includes a lens 11 and a photoelectric conversion unit 12, and is not particularly limited as long as it is an apparatus that can capture an imaging target such as a granular material moving in the air as a still image. Can be adopted. Examples of such an imaging device include a CCD area camera and a line scan camera. From the viewpoint of improving the efficiency of image processing, it is preferable to use an imaging device including a photoelectric conversion unit 12 having a plurality of photoelectric conversion elements, and in particular, a photoelectric conversion in which a plurality of photoelectric conversion elements such as a line scan camera are arranged in a row. It is more preferable to use an imaging device having a unit. The photoelectric conversion element may be a charge-coupled device (CCD) or a CMOS sensor. The photoelectric conversion element does not necessarily need to be a color photoelectric conversion element, and is preferably, for example, a photoelectric conversion element capable of expressing a gray scale of 256 gradations, and a photoelectric conversion element capable of expressing a higher gradation. Is more preferred. It is preferable to increase the resolution of the particles to be imaged in order to obtain a clearer image.

  The imaging device 10 further includes a housing 40. The shape and material of the housing 40 are not particularly limited as long as at least a lens of the imaging device 10 can be accommodated in the housing 40, and examples of the shape include a cylindrical shape and a box shape. Examples of the material include wood, plastic, and metal. The housing 40 may itself be light transmissive or light impermeable. The dimensions of the housing 40 are not particularly limited as long as at least the lens 11 can be accommodated in the housing 40, and can be appropriately adjusted according to the dimensions of the imaging device 10 to be used.

  As shown in FIG. 1, the entire imaging device 10 is housed in a housing 40 from the viewpoint of performing stable imaging while preventing contamination of the lens by the imaging target and facilitating maintenance of the imaging device 10. More preferably, it is. The housing 40 shown in the figure is a box-shaped member, in which the entire imaging device 10 is housed.

  As shown in FIG. 1, the housing 40 preferably has a penetrating light receiving window 40A. The light receiving window 40A shown in the figure is disposed at a portion facing the light receiving surface 11S of the lens 11, and is capable of receiving light on at least a part of the light receiving surface 11S. With such a configuration, it is possible to stably image the imaging target while preventing unintended contamination of the light receiving surface 11S of the lens by the imaging target.

  The housing 40 is preferably configured so that at least the periphery of the light receiving window 40A is shielded from light. By adopting such a configuration, even when the periphery of the light receiving window 40A in the housing 40 is contaminated with the imaging target with the lapse of the imaging time, the imaging of the imaging target can be performed without depending on the contamination. It can be performed stably. The light shielding method of the housing 40 may be, for example, using a housing 40 made of a light-impermeable member or a light-reflective member such as a black member or a metal member, or a light-impermeable material on the outer surface or inner surface of the housing 40. It can be performed by attaching a member or a light reflective member.

  FIG. 2A is an enlarged view of a main part of the imaging device 10 in FIG. As shown in the figure, the housing 40 further includes a gas inlet 50. The gas inlet 50 is a through-hole that supplies gas such as air from the outside into the housing 40. In the figure, a gas supply unit 60 for supplying gas such as a pump is connected to a gas introduction port 50 via a gas introduction path 61.

  From the viewpoint of performing stable imaging of the imaging target, it is preferable that the gas inlet 50 be disposed at a portion of the housing 40 that does not block light from entering the light receiving window 40A. For example, when the entire imaging device 10 is housed in the box-shaped housing 40, the gas inlet 50 may be arranged on the top surface, the bottom surface, or the back surface of the housing, or may be positioned from the light receiving surface 11S of the lens. Can also be placed rearward. The gas inlet 50 may be provided at one place or at a plurality of places.

  As shown in FIG. 1, the imaging device 10 is housed in the housing 40 having the light receiving window 40 </ b> A and the gas inlet 50, and allows the gas supplied into the housing 40 to flow through the gas inlet 50. It is possible to take an image while discharging the gas flow A through the light receiving window 40A. With such a configuration, it is possible to prevent the imaging object from adhering to the light receiving window 40A due to the gas flow A discharged through the light receiving window 40A. Even if it does, the attached matter can be easily blown off. As a result, contamination of the imaging field of view of the imaging device can be prevented, and stable imaging of the imaging target can be performed.

  In particular, the light receiving window 40 </ b> A coincides with the viewable field of the photoelectric conversion unit 12 of the imaging device 10 from the viewpoint of more effectively ensuring the appropriate light amount for imaging and more stable imaging of the imaging target. Alternatively, it is preferable to provide the similar shape larger than the visual field. Since the viewable field of view of the photoelectric conversion unit 12 is determined by the arrangement position of the photoelectric conversion element built in the photoelectric conversion unit 12, as shown in FIG. When an imaging device in which a plurality of photoelectric conversion elements 15 are arranged in a row is used, a rectangular light receiving window 40A having a dimension capable of securing at least the entire field of view that can be imaged, corresponding to the arrangement of the photoelectric conversion elements 15. Can be provided.

  As described above, when the line scan camera is used as the imaging device 10, the light receiving window 40A is supplied from the gas inlet 50 by making the shape of the light receiving window 40A rectangular, as compared with the case where the shape is circular. Even when the flow rate of the gas is small, the gas can be sufficiently exhausted from the light receiving window 40A, and contamination by the imaging object in the light receiving window 40A and its vicinity can be prevented. As a result, more stable imaging of the imaging target can be realized.

  Even when the flow rate of the gas supplied from the gas inlet 50 is small, the light receiving window 40A has a rectangular shape from the viewpoint of enabling the gas to be discharged from the inside of the housing 40 and realizing more stable imaging of the imaging target. It is preferable that the dimensions have the following relationship.

  That is, as shown in FIGS. 2A to 2C, the casing 40 is formed in a box shape, and a member facing the light receiving surface 11S of the lens in the casing 40 (hereinafter, this member is referred to as a “casing facing member 40S”). When both the light receiving window 40A and the light receiving window 40A are rectangular, the height H1 of the light receiving window 40A (the length H1 in the X direction in FIG. 2B) is equal to the height of the housing facing member 40S. H1 / H2 is preferably 2/3 times or less, more preferably 1/2 times or less, and even more preferably 1/10 times or less of H2.

  From a similar viewpoint, the width W1 of the light receiving window 40A (the length W1 in the Y direction in FIG. 2B) is not more than one time as W1 / W2 with respect to the width W2 of the housing facing member 40S. Is preferably 3/4 or less, more preferably 1/2 or less.

  In addition, from a similar viewpoint, the depth D1 of the light receiving window 40A (the length D1 in the Z direction in FIG. 2C) can be the same as the thickness of the housing facing member 40S.

  Specifically, the height H1 of the light receiving window 40A is preferably 0.3 mm or more, more preferably 0.5 mm or more, still more preferably 1 mm or more, and 5 cm or less. Preferably, it is 3 cm or less, more preferably, 1 cm or less.

  The width W1 of the light receiving window 40A is preferably 5 mm or more, more preferably 1 cm or more, still more preferably 3 cm or more, and preferably 30 cm or less, and more preferably 10 cm or less. It is more preferably 5 cm or less.

  The depth D1 of the light receiving window 40A is preferably 3 cm or less, more preferably 1 cm or less, and even more preferably 1 mm or less.

  From the viewpoint of securing stable light quantity for imaging and performing stable imaging of an imaging target, when the lens 11 has a circular shape, the height H1 of the light receiving window 40A is equal to the diameter C1 of the lens 11 ( 2 (b), H1 / C1 is preferably 1/100 or more, more preferably 1/20 or more, and even more preferably 1/10 or more. .

  From the same viewpoint, the width W1 of the light-receiving window 40A is preferably 1/100 times or more, more preferably 1/10 times or more, as W1 / C1, with respect to the diameter C1 of the lens 11. More preferably, it is 1/2 times or more.

  From the same viewpoint, the distance L1 between the light receiving surface 11S of the lens and the light receiving window 40A can be appropriately adjusted depending on the focal length of the lens to be used. It is preferably at most 1 times, more preferably at most 1/2 times, even more preferably at most 1/5 times.

  Specifically, the distance L1 between the light receiving surface 11S of the lens and the light receiving window 40A is preferably 0.1 mm or more, more preferably 1 mm or more, still more preferably 5 mm or more, and 10 cm or less. Is preferably 5 cm or less, more preferably 3 cm or less. With such dimensions, the gas supplied from the gas supply unit 60 can be easily discharged from the inside of the housing 40 through the light receiving window 40A.

  The gas is supplied from the gas supply unit 60 through the gas inlet 50 from the viewpoint of realizing stable imaging of the object to be imaged while securing the discharge of the gas from the light receiving window 40A so as not to disturb the movement of the granular material. The flow rate of the gas can be changed as appropriate according to the degree of introduction of the gas from the gas supply unit 60, and the flow rate of the gas is set in a range described later according to the shape and size of the light receiving window 40A and the internal volume of the housing 40. Is preferred. In the present embodiment, the flow rate of the gas supplied from the gas supply unit 60 through the gas inlet 50 is preferably 0.01 m / s or more, more preferably 0.1 m / s or more, and 0.1 m / s or more. It is more preferably at least 3 m / s, more preferably at most 1 m / s, more preferably at most 0.8 m / s, even more preferably at most 0.6 m / s.

  The imaging device 10 can target a powder or the like that moves in the air by free fall, scattering, airflow, or the like. Examples of the imaging object include paper powder, pulp, wood flour, activated carbon, sugar, flour, resin pellets, resin beads, particles of organic substances such as particles of water-absorbing polymer, metal powder, sodium chloride, potassium chloride, Examples thereof include powders of metals or metal salts such as calcium chloride, magnesium chloride and lime, and powders of inorganic substances such as glass. These powders and granules may be further mixed, added or coated with a binder such as a pressure-sensitive adhesive to have tackiness. The shape of the powder is not particularly limited, and examples thereof include a sphere, a stone, an ellipse, and a needle.

  Since the imaging target is a granular material, the granular material may be scattered in a process such as dropping, and may adhere and accumulate on unintended members or regions such as the imaging device 10. In particular, particles having deliquescence, such as magnesium chloride, and particles, which are composed of sticky particles such as a water-absorbing polymer, are adhered and deposited on unintended members and regions. It will be very difficult. In this regard, since the imaging apparatus of the present invention has the housing 40 that covers at least the lens 11, even when a powdery or granular material having deliquescence or tackiness is to be imaged, the vicinity of the lens 11 and the light receiving window 40A Can be prevented from being blown off by the gas flow A discharged from the inside of the housing 40 through the light receiving window 40A and adhering to the light receiving window 40A. As a result, the imaging field of view of the imaging device can be secured, and stable imaging can be realized.

  An image processing unit 70 is preferably connected to the imaging device 10 from the viewpoint that imaging of an imaging target is performed over time in a product manufacturing process and that data can be processed in real time. The image processing unit 70 includes a plurality of components (not shown) such as an electric signal processing unit, a density determination processing unit, a calculation unit, an analysis unit, and a processing unit (not shown). The converted electric signal can be imaged. The image processing unit 70 may be further connected to the illumination unit 20 so that the illumination intensity is automatically adjusted based on the electric signal transmitted to the image processing unit 70. As the image processing unit 70, for example, a computer in which image processing software or the like is installed, a device constructed based on an image controller, or the like can be used.

  An imaging method according to the present invention is an imaging method of imaging a granular material moving in the air as an imaging target using the imaging device having the above-described configuration. In particular, in the present method, since the gas supplied from the gas inlet 50 into the housing 40 is imaged while being discharged through the light receiving window 40A, dust, dust, particles, and the like floating outside the housing are removed from the light receiving window 40A. Intrusion into the housing can be prevented, and as a result, the imaging field of view of the imaging device can be secured and stable imaging can be realized.

  The imaging device and the imaging method of the present invention are not limited to the above embodiment. For example, although the case 40 has been described as being box-shaped, the case 40 may have a shape other than a box shape such as a cylindrical shape as long as the effects of the present invention are exerted. When the housing 40 is cylindrical, the circular surface of the housing 40 can be used as the housing facing member 40S, and the height H2 and the width W2 of the member 40S are the diameters of the member 40S, respectively. be able to.

  In addition, the above-described case 40 has been described as a box-shaped one having no opening except for the light-receiving window, but is not limited to this as long as the effects of the present invention are achieved. For example, the imaging device 10 can be placed on a flat member, and after that, an image can be taken by covering the imaging device 10 with a box-shaped housing 40 having an open bottom surface.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples.

[Example 1]
As shown in FIG. 1, the imaging target was imaged with the lapse of time using the imaging device 10 housed in the housing 40. In detail, the imaging device is dropped in the air as an imaging target in a state where the imaging device is housed in the housing 40 having the light receiving window 40A and the gas inlet 50 so that the light receiving window and the light receiving surface 11S of the lens face each other. An image of the granular material 30 was obtained. The dimensions of the light receiving window 40A were 5 mm in height × 40 mm in width × 0.1 mm in depth, and the inner volume of the housing 40 was 0.54 L. Gas (air) is supplied at 0.42 m / s through the gas inlet 50 into the housing 40, and the air can be discharged through the light receiving window 40A. As the imaging device 10, a line scan camera (XG-HL04M manufactured by Keyence Corporation) was used. The line scan camera was connected to the image processing unit 70, and automatically performed a shading process on a captured image due to a change in shading of the background. FIG. 3A shows the change in the number of pixels over time.

[Comparative Example 1]
In this comparative example, the housing 40 was not used. Then, while blowing gas at 1 m / s directly onto the light receiving surface of the lens, imaging of the powder particles falling in the air was performed with time. Otherwise, imaging was performed in the same manner as in Example 1. The change in the number of pixels over time is shown in FIG.

  As shown in FIG. 3A, it can be seen that the imaging apparatus of the embodiment has a very small change in the number of pixels over time, and can more stably image the imaging target. On the other hand, as shown in FIG. 3B, in the imaging device of the comparative example, it can be seen that the number of pixels decreases over time, and the imaging target cannot be imaged stably. The reason for this is that the light receiving surface of the lens in the imaging device of the comparative example is so contaminated that it is impossible to remove the imaging target by blowing gas, and even if background shading is performed, It is considered that the background was so dark that it could not be handled, and as a result, it was not possible to clearly image the imaging target.

Reference Signs List 10 imaging device 11 lens 11S light receiving surface of lens 12 photoelectric conversion unit 30 imaging target (powder and granular material)
Reference Signs List 40 housing 40A light receiving window 40S housing facing member 50 gas inlet 60 gas supply unit 70 image processing unit

Claims (6)

An imaging apparatus including a lens and a photoelectric conversion unit that converts light collected by the lens into an electric signal,
At least the lens of the imaging device is housed in a housing,
The housing has a penetrating light-receiving window that allows light to enter at least a part of the light-receiving surface at a portion facing the light-receiving surface of the lens, and blocks light from entering the light-receiving window. Has a gas inlet in a non-
An imaging device configured to capture an image of a gas supplied into the housing through the gas inlet while discharging the gas through the light receiving window.   The imaging device according to claim 1, wherein the housing is configured to shield light around the light receiving window.   The imaging device according to claim 1, wherein the photoelectric conversion unit includes a plurality of photoelectric conversion elements arranged in a row.   The imaging device according to any one of claims 1 to 3, wherein a powder moving in the air is an imaging target.   The imaging device according to claim 4, wherein the particles are particles having adhesiveness, and the particles falling in the air are to be imaged. An imaging method for imaging a granular material moving in the air by a lens and an imaging device including a photoelectric conversion unit that converts light collected by the lens into an electric signal,
At least the lens of the imaging device is housed in a housing,
The housing has a penetrating light-receiving window that allows light to enter at least a part of the light-receiving surface at a portion facing the light-receiving surface of the lens, and blocks light from entering the light-receiving window. Has a gas inlet in a non-
An imaging method, wherein imaging is performed while discharging the gas supplied into the housing through the gas inlet through the light receiving window.

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