JP2014190730A - Lighting device for printed matter inspection and inspection equipment of printed matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To give a function for securing a uniform optical path from a test object to an imaging apparatus for a long time while maintaining sealability in a housing in a lighting device for printed matter inspection which has a plurality of light sources in the same housing, and constituted so that the housing is arranged on the optical path (or its extension line), and thus, to provide inspection equipment of a printed matter which can be stably operated without being influenced by disturbance such as powder dust, refuse, contact of the test object.SOLUTION: A lighting device for printed matter inspection is used for inspection equipment of a printed matter 10 to be conveyed, and has: a plurality of light sources 21, 22 arranged by extending so as to orthogonally cross a conveyance direction to the printed matter; a housing 23 which stores the plurality of light sources at one part; and a cavity part 24 opened to the surrounding environment of the housing between any two adjacent light sources among the plurality of light sources stored in the housing.

Description

  The present invention relates to an illuminating device used for inspecting continuously printed sheet-like printed materials and an inspecting device using the illuminating device.

  In a general manufacturing process of a sheet-like printed matter by gravure printing or the like, after printing a predetermined pattern on a sheet-like original fabric, the printed matter is conveyed at a predetermined speed, and imaging means such as a line sensor camera included in the inspection apparatus Thus, the surface of the conveyed printed material is imaged, and the printed material is inspected by determining the presence or absence of defects on the printed material using the image data obtained at that time.

  In such inspection of printed matter, in order to acquire image data having a predetermined brightness, some illumination means for irradiating illumination light to the inspection subject is required.

  Illumination means used for inspection of printed materials are roughly divided into transmission, regular reflection, and irregular reflection methods based on the positional relationship of the light source, inspection object, and imaging device, and various inspection conditions such as inspection items and surface properties of the inspection object. Accordingly, the optimum illumination means including the simultaneous use of a plurality of methods is applied. As the light source, a light source that can illuminate the surface of the inspection object along the imaging line is suitable, and specifically, a fluorescent lamp, a transmission light, an LED, or the like is used. In many cases, two or more light sources are arranged in parallel from the viewpoint of simultaneous use of a plurality of systems described above, or simply from the viewpoint of securing a light quantity.

  As an illumination device for printed matter inspection having such characteristics, for example, forms as disclosed in Patent Documents 1 and 2 are conceivable. In either case, a straight tube fluorescent lamp is used as a light source, and a plurality of light sources are arranged in the apparatus.

  In the illumination device described in Patent Document 1, each light source is stored in an individual casing. When such a structure is adopted, the degree of freedom in the arrangement of each light source is limited by the amount of the casing. Further, when the number of light sources is large, the size of the entire apparatus becomes large, and it may be unsuitable for an environment in which installation space is restricted due to the convenience of the manufacturing side. Furthermore, each case must be accessed individually during maintenance such as tube replacement, which is not efficient.

  On the other hand, in the illumination device described in Patent Document 2, each light source of the reflection method is stored in the same casing. When such a structure is adopted, it can be said that it has an advantage over the structure of Patent Document 1 in terms of the degree of freedom of light source arrangement, downsizing of the apparatus, and maintainability.

  Here, especially when arranging a plurality of light sources with the intention of securing the light quantity, each light source is imaged on the surface of the object to be inspected as much as possible without interfering with the optical path from the object to be inspected to the imaging device. It is most desirable to place it close to. As a result, there is a case where the optical path is arranged to pass between the respective reflection-type light sources as in the illumination devices described in Patent Document 1 and Patent Document 2. In other words, an illumination device may be installed on the optical path from the object to be inspected to the imaging device.

  At this time, in an apparatus having a structure in which each light source is housed in the same housing as in Patent Document 2, predetermined locations are provided at two locations (the entrance side and the exit side of the path) on the housing in order to secure an optical path. It is necessary to provide a transmission part. This transmission part must be kept in a uniform state in the long term with respect to the imaging line direction.

  As a first means for providing the transmission part, it is conceivable to use a transparent member at the location. However, the optical path is uniform due to dust and fine dust generated in the manufacturing process and the surrounding environment during operation, or due to the occurrence of scratches caused by contact of the inspection object conveyed at high speed with the transparent member. However, there is a problem that the performance of the image pickup apparatus is deteriorated with time and the image data acquired by the imaging apparatus is deteriorated, that is, the performance of the inspection apparatus is lowered.

  As a second means, it is conceivable to open the part to the surrounding environment. Thereby, the uniformity of the optical path can be maintained. However, since the airtightness in the housing is impaired, there is a problem in that the lighting device malfunctions or breaks down due to the ingress of dust or dust, contact of the inspection object with the light source, and the like.

Japanese Patent No. 3808937 Japanese Patent No. 4599477

  Therefore, the present invention is a printed matter characterized by having a structure in which a plurality of light sources are provided in the same casing, and the casing is arranged on an optical path (or an extension thereof) from the object to be inspected to the imaging device. In the lighting equipment for inspection, a function to ensure a long-term uniform optical path while maintaining the airtightness in the housing is added, and thereby, disturbance such as contact of dust, dust, and inspected objects can be prevented. It is an object of the present invention to provide a printed matter inspection apparatus that is not affected and can be stably operated.

As means for solving the above-mentioned problems, the invention of claim 1 is an illumination device used in an inspection apparatus for a printed matter to be conveyed,
A plurality of light sources arranged to extend perpendicular to the transport direction with respect to the printed matter;
A housing for storing the plurality of light sources in one place;
For inspection of printed matter, comprising: a hollow portion that is open to the surrounding environment of the casing between any two adjacent light sources among the plurality of light sources stored in the casing. It is a lighting device.

The invention of claim 2 is an inspection apparatus for printed matter conveyed at a predetermined speed,
Imaging means for imaging the surface of the printed matter in synchronization with the predetermined speed;
Reflective illumination means for irradiating light on the surface of the printed matter;
Transmitted illumination means for irradiating the back of the printed matter with light;
Extracting defects present in the printed matter using image data obtained by imaging the surface of the printed matter by the imaging means, and comprising image processing / defect determining means for automatic determination,
The printed illumination inspection apparatus according to claim 1, wherein the reflected illumination unit is the illumination device for printed matter inspection according to claim 1.

  According to the present invention, the optical path is kept in a uniform state without being affected by various disturbances by imaging an object to be inspected through the hollow portion formed in the casing of the illumination apparatus. . In addition, since the airtightness in the housing is ensured by the inner wall of the hollow portion, the light source portion can be excluded from the influence of various disturbances. Thereby, even in an environment with many disturbance factors, such as a manufacturing process in which a lot of dust is generated, it is possible to maintain an appropriate optical system state and operation for a long period of time and to provide an inspection apparatus that can be stably operated.

  In addition, due to the above, operational problems with respect to an illumination device having a structure having a plurality of light sources in the same housing have been solved, taking advantage of the freedom of light source arrangement, ease of miniaturization, and high maintainability. Thus, it is possible to provide an illumination device and an inspection device for various printed matter inspection needs.

It is a schematic sectional drawing which shows an example of a structure of the illuminating device for printed matter inspection of this invention. It is a schematic sectional drawing which shows an example of a structure of the illuminating device for printed matter inspection of this invention. It is the schematic which shows an example of a structure of the inspection apparatus of the printed matter in this invention. It is the schematic which shows an example of arrangement | positioning of the imaging part 40, the reflective illumination part 20, and the permeation | transmission illumination part 30 in the inspection apparatus of this invention.

  Hereinafter, embodiments of an illumination device and an inspection device for printed matter inspection according to the present invention will be described with reference to the drawings.

1 and 2 are schematic cross-sectional views showing an example of the configuration of an illumination device for printed matter inspection according to the present invention.
The illumination device for printed matter inspection of the present invention has a first reflected illumination light source 21 and a second reflected illumination light source 22 arranged so as to extend perpendicular to the carrying direction with respect to the printed matter 10 to be conveyed. Between the first reflected illumination light source 21 and the second reflected illumination light source 22, and the reflected illumination housing 23 between the first reflected illumination light source 21 and the second reflected illumination light source 22. And a cavity portion 24 of the reflective illumination housing that is open to the surrounding environment. When there are three or more reflected illumination light sources for the cavity portion 24 of the reflected illumination casing, the cavity portion of the reflected illumination casing is open to the surrounding environment between any two adjacent light sources. be able to.

  The first reflected illumination light source 21 and the second reflected illumination light source 22 use light sources that can illuminate the surface of the printed matter 10 in a line. In the embodiment of the present invention, a straight tube fluorescent lamp is assumed which has a high degree of freedom in arrangement due to its simple structure and is inexpensive, but other light sources such as LEDs are used if irradiation is possible in a line shape. It doesn't matter. Further, the number and arrangement of the light sources need not be limited to two symmetrical arrangements as in the first illumination light source 21 and the second illumination light source 22 of the present embodiment. Two or more light sources can be arranged in various positional relations according to conditions such as an irradiation angle with respect to. However, due to the structure in which the cavity portion 24 of the reflection illumination housing is formed in the reflection illumination housing 23, each light source is inside the reflection illumination housing 23 and a portion excluding the cavity portion 24 of the reflection illumination housing Need to be placed in. In addition to the light source, for example, a structure such as a reflecting mirror for improving the light collection efficiency on the printed material 10 may be appropriately arranged as necessary.

  In order to protect the internal light source from various disturbances, the reflective illumination housing 23 is basically a robust structure using a metal material, and further, a treatment that does not generate extra reflected light or scattered light by black alumite treatment or the like. It is desirable to apply. Further, in order to irradiate the printed matter 10 with light from the first reflected illumination light source 21 and the second reflected illumination light source 22, a transparent portion 25 of a predetermined reflective illumination housing is provided on the side facing the printed matter 10.

  As a constituent member of the transparent portion 25 of the reflective illumination housing, it is desirable to use a highly transparent material having a transmittance of approximately 80% or more, such as a resin such as acrylic or polycarbonate, or glass. In addition, the distance between the transparent portion 25 of the reflective illumination housing and the surface of the printed material 10 is set to an appropriate distance within a range where no excessive contact occurs between the two during normal inspection.

  The cavity portion 24 of the reflective illumination housing assumes that the illumination device is arranged on an optical path connecting the printed material 10 as the inspection object and the imaging camera, or on an extension line thereof, and the optical path is arranged inside the illumination device. The purpose is to ensure. In the present embodiment, it is assumed that the imaging camera is arranged directly above the illumination device, and the cavity of the reflective illumination housing is vertically penetrated between the first reflected illumination light source 21 and the second reflected illumination light source 22. Although the portion 24 is formed, this is not limited depending on the configuration of the optical system. That is, when the arrangement of the illumination device and the imaging camera with respect to the printed material 10 that is the inspection object is determined and the path of the optical path is determined, the position of the cavity portion 24 of the reflective illumination housing is determined so that the path is secured. It is necessary to decide.

  The dimension (inner dimension) of the cavity portion 24 of the reflective illumination housing is a prerequisite that the reflective illumination housing 23 does not interfere with the field of view of the imaging camera, and the lower limit is determined based on the specifications on the imaging camera side. Is done. That is, the imaging range on the reflective illumination housing 23 is obtained for each of the conveyance direction of the printed matter and the orthogonal direction (imaging line direction), and the displacement in each direction due to disturbance such as vibration during operation of the apparatus is obtained with respect to these values. In consideration of this, it is desirable to set a dimension having a certain margin with respect to the imaging range. For example, when a displacement of about several millimeters in each direction is conceivable with respect to the imaging range of 1 mm × 1200 mm, the inner dimension of the cavity portion 24 of the reflective illumination housing is 10 mm × 1210 mm or more.

  The constituent member of the inner wall 26 of the reflective illumination housing of the cavity portion 24 of the reflective illumination housing may be made of the same metal material as that of the reflective illumination housing 23 or may be the same transparent material as that of the transparent portion 25 of the reflective illumination housing. It is also possible to use other materials. FIG. 1 shows an example in which a metal material is used for the inner wall 26 of the reflective illumination housing, and FIG. 2 shows an example in which a transparent material is used for the inner wall 26 of the reflective illumination housing. The configuration of FIG. 2 is superior in securing the amount of light because the ratio of the transparent portion 25 of the reflective illumination housing to the configuration of FIG. 1 is large and the range of the irradiation angle with respect to the printed matter 10 is widened. On the other hand, when it is necessary to make the unevenness of the surface of the printed matter 10 stand out, it is more effective to narrow the irradiation angle range and provide directivity by adopting the configuration of FIG. In this way, a more suitable structure can be selected in view of the inspection items and the surface properties of the printed material 10.

  When the configuration of FIG. 2 is selected, the structure of the transparent portion 25 of the reflective illumination housing is more complicated than that of the configuration of FIG. Further, when a resin-based material is used as the transparent material, the dimensional accuracy of the inner wall 26 of the reflective illumination housing is lowered mainly due to the heat effect from the light source. It is desirable to have a structure with a margin in the inner dimension of the cavity portion 24 of the reflective illumination housing, compared to the case of using the above.

FIG. 3 is a schematic diagram showing an example of the configuration of a printed matter inspection apparatus according to the present invention.
The configuration will be described. A printing machine (not shown) transports the printed material 10 at a predetermined speed, and an imaging unit 40 that images the surface of the printed material 10 in synchronization with the predetermined speed, and reflected illumination that irradiates the surface of the printed material 10 with light. Using the image data obtained by imaging the surface of the printed matter 10 by the image capturing unit 40, the transmitted illumination unit 30 that irradiates light on the back surface of the printed part 10, the part 20, the defects existing in the printed matter 10 are extracted, The image processing / defect determination unit 50 is configured to automatically determine.

  Here, the printed material 10 is transported and moved in the imaging field of view at a predetermined speed. The speed varies depending on the production line, but in a general production process of a sheet-like printed matter by gravure printing or the like, it is generally 300 m or less per minute. At this time, a signal for each unit distance is obtained from a unit that measures the amount of movement of the printed material 10 attached to the printing machine with high accuracy, and the signal may be divided and distributed to the image processing / defect determination unit 50 in some cases. Scanning imaging is performed so as not to be affected by the speed fluctuation of the printing press.

When the conveyance speed of the printing press can be regarded as constant within the resolution range of the imaging unit 40, a method of obtaining an image only by starting imaging with a trigger signal and imaging at a predetermined time interval may be considered. Imaging that is always synchronized with the conveyance speed of the printing press is more reliable.

  FIG. 4 is a schematic diagram illustrating an example of the arrangement of the imaging unit 40, the reflected illumination unit 20, and the transmitted illumination unit 30 in the inspection apparatus of the present invention.

  The imaging unit 40 includes an imaging camera 41 and an imaging lens 42, and is disposed immediately above the printed matter 10 that is an imaging target. At this time, since the printed material 10 always passes under the imaging unit 40 at a predetermined speed, it is suitable to use a line sensor camera as the imaging camera 41. However, an area sensor camera can also be used depending on the type of printing press, in particular, the form of conveyance. In general pattern inspection of printed matter, an imaging resolution of about 0.1 to 0.5 mm is required, and an optimal imaging camera 41 is based on required items such as moving speed, imaging width and working distance of the printed matter 10. It is desirable to select the combination of the image pickup lenses 42 and the number of arrangement of them in the image pickup line direction (a direction parallel to the printed matter 10 and perpendicular to the transport direction).

  In the present invention, the imaging unit 40 is arranged perpendicularly to the surface of the printed matter 10. However, when a line sensor camera is used as the imaging camera 41, an appropriate illumination system can be realized and each pixel in the imaging line direction can be realized. As long as the printed matter 10 can be imaged from the same distance, the angle θ shown in FIG. 4 may be tilted according to the situation such as the installation environment.

The reflective illumination unit 20 is disposed between the printed material 10 and the imaging unit 40 and is configured by the illumination device illustrated in FIGS. 1 and 2. As shown in FIG. 4, by arranging the printed matter 10, the reflective illumination unit 20, and the imaging unit 40 in a straight line, the imaging unit 40 images the printed matter 10 through the cavity portion 24 of the reflective illumination housing of the reflective illumination unit 20. It becomes possible to do. When the imaging unit 40 is disposed with the angle θ shown in FIG. 4 inclined, the reflective illumination unit 20 may be similarly disposed with the angle θ inclined to secure an optical path.
As described above, the configuration of the lighting device in which the two light sources illustrated in FIGS. 1 and 2 are housed in one housing has been described. If the housing does not interfere with the optical path, the light source and the light source It can be configured with an additional housing.

  The transmitted illumination unit 30 is arranged so that the printed product 10 is positioned between the imaging unit 40 and the transmitted illumination unit 30, and stores the transmitted illumination light source 31 that irradiates light on the back surface of the printed product 10 and the transmitted illumination light source 31. The transmitted illumination housing 32 is configured. As the transmitted illumination light source 31, a light source that can illuminate the printed material 10 in a line shape is used as in the case of the reflective illumination unit 20. A transparent portion 33 of a predetermined transmissive illumination housing is provided on the side of the transmissive illumination housing 32 that faces the printed matter 10 in order to irradiate light from the transmissive illumination light source 31.

  In the present invention, the transmission illumination unit 30 is arranged in the vertical direction of the imaging unit 40 for the purpose of obtaining the maximum amount of light with a single light source. However, as long as the amount of light that does not hinder the detection of defects can be secured. The number and arrangement of the light sources may be appropriately changed as necessary. Moreover, when using the raw material with especially low transparency, the transmission illumination part 30 does not need to be arrange | positioned. However, when it is attached to a printing press in which the original fabric is to be conveyed, it is suitable that the transmission illumination unit 30 can be used / not used.

4 shows a configuration in which the illuminating device shown in FIGS. 1 and 2 is not used in the transmissive illumination unit 30, but a configuration using the illuminating device shown in FIGS. 1 and 2 may be employed. . Specifically, when the image data is significantly deteriorated due to dust, dust, or scratches generated on the transparent portion 33 of the transmissive illumination housing in the configuration of FIG. 3, the illumination device of FIGS. The effect can be eliminated by arranging in the. However, such a situation is limited to the case where the transparency of the printed material 10 is particularly high and the contribution of the transmissive illumination unit 30 is dominant in the image data, and thus the effect can be said to be limited.

  The image data acquired by the imaging unit 40 is sent to the image processing / defect determination unit 50. When the imaging unit 40 is composed of a plurality of imaging cameras, a method of arranging the image processing / control units 50 in parallel according to the number is simple, but the method is not particularly limited.

  In the image processing / defect determination unit 50, in order to inspect all the objects with high accuracy, the image obtained at the time of conveyance is set as a reference image, and comparison processing is executed. In general, one round of a plate for forming the printed material 10 is processed as an image unit.

  For specific methods of inspection processing, centering on the difference processing between the reference image obtained during transport and the inspection image to be inspected, alignment processing by pattern matching, normalized correlation, etc., averaging and maximization, etc. As long as it is possible to reveal defects to be detected by processing by filtering processing, labeling processing to extract defect information from binary information obtained in the middle, etc., any processing method May be adopted.

10 .. Printed matter 20. .. Reflection illumination unit 21 .. First reflection illumination light source 22. .. Second reflection illumination light source 23 .. Reflection illumination case 24 .. Hollow portion 25 of reflection illumination case .. Reflection illumination case The transparent portion 26 of the reflective illumination housing 30 The transmission illumination portion 31 The transmission illumination light source 32 The transmission illumination housing 33 The transparent portion 40 of the transmission illumination housing The imaging unit 41 Camera 42 .. Imaging lens 50.. Image processing / Defect determination unit

Claims (2)

An illumination device used for an inspection device for a printed matter to be conveyed,
A plurality of light sources arranged to extend perpendicular to the transport direction with respect to the printed matter;
A housing for storing the plurality of light sources in one place;
For inspection of printed matter, comprising: a hollow portion that is open to the surrounding environment of the casing between any two adjacent light sources among the plurality of light sources stored in the casing. Lighting device. An inspection device for printed matter conveyed at a predetermined speed,
Imaging means for imaging the surface of the printed matter in synchronization with the predetermined speed;
Reflective illumination means for irradiating light on the surface of the printed matter;
Transmitted illumination means for irradiating the back of the printed matter with light;
Extracting defects present in the printed matter using image data obtained by imaging the surface of the printed matter by the imaging means, and comprising image processing / defect determining means for automatic determination,
The printed matter inspection apparatus according to claim 1, wherein the reflected illumination unit is the printed product inspection illumination device according to claim 1.

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