JP5589423B2 - Transparent flat plate detection system - Google Patents

Description

  The present invention relates to a transparent flat plate detection system. More specifically, the present invention relates to a transparent flat plate detection system that can easily and accurately detect a transparent flat plate by image processing.

  Transparent plastic molded articles (transparent bodies) are widely used as optical components such as displays and optical disks. However, when a transparent object is an object to be imaged, the transparent object has low reflectance and high transmittance and cannot be contrasted with the background. Therefore, the transparent object is detected using a camera that uses only normal luminance information. Was difficult.

  For such a problem, as shown in FIG. 19, Patent Document 1 discloses a light projection in which light is polarized in a specific direction by a light projection side polarizing plate 95 and projected onto a predetermined region including the transparent body 90. An apparatus 91, a polarizing device 92 having a light receiving side polarizing plate 96 that transmits only specific polarized light out of the light transmitted through the predetermined region, and an image obtained by receiving the light transmitted through the light receiving side polarizing plate 96, A television camera 93 that captures a two-dimensional image, and an image processing device 94 that detects a transparent body 90 using a brightness / darkness distribution in the image obtained from the television camera 93, and that is configured to emit light polarized in a specific direction. Then, light is projected onto a predetermined area including the transparent body 90, and the light transmitted through the predetermined area is transmitted through a light-receiving side polarizing plate 96 that transmits only specific polarized light, and then is transmitted to the CCD in the TV camera 93. Received light and obtained from this CCD Using the brightness distribution in the image, the transparent object detection method for detecting a transparent body 90 is disclosed.

  However, the technique described in Patent Document 1 attempts to detect a transparent body using the birefringence of the transparent body, and is difficult to detect on a transparent flat plate such as a glass flat plate that does not have birefringence. There is a problem that there is.

  On the other hand, as a technique for detecting an image of a flat plate, Japanese Patent Application Laid-Open No. H10-228867 discloses that polarized light different in reflected light from the surface of the steel plate 81 is detected by line sensor cameras 82a to 82c as shown in FIG. A surface inspection apparatus for forming an image showing the intensity distribution is disclosed.

(Problem 1: Arrangement of lighting device)
In the technique described in Patent Document 1, it is necessary to dispose the illumination device 97 and the light projecting side polarizing plate 96 below the transparent body 90. However, in an actual line or the like, there is a process of cleaning the transparent flat plate, and water drops may fall on the lower side. Therefore, it is difficult to arrange the lighting device 97 below the transparent flat plate due to safety considerations. There is a case.

  In the technique described in Patent Document 2, it is necessary to dispose the light projecting unit 83 and the polarizer so as to face the camera 82. Therefore, when the steel plate 81 to be examined is a transparent flat body, it is necessary to illuminate the entire transparent flat body. Therefore, in the case where there are a large number of transparent flat bodies or a transparent flat body having a large size, there is a problem in that the size of the system is increased because the lighting device or the lighting device having a large light emitting area is disposed separately.

(Problem 2: Relocation from tray to detector)
In addition, the technique described in Patent Document 1 has a problem in that when the process is performed integrally with the tray or the mounting table and the tray, it is necessary to mount the process once on the transparent body detection device.

(Problem 3: Necessity of rotation mechanism and calibration)
Furthermore, the technique described in Patent Document 1 requires that the transmission polarization directions of the light-projecting side polarizing plate 95 and the light-receiving side polarizing plate 96 coincide with each other or be orthogonal to each other. It was necessary to rotate and measure based on each image. When this is performed according to a change in the type of the transparent body 90, etc., this leads to a time loss on the process line. In addition, providing such a rotation mechanism is a factor in increasing the size of the apparatus. Furthermore, such a rotating mechanism is prone to change over time (center position deviation, etc.) of the mechanism itself with vibration as in a factory, requiring maintenance such as failure due to wear of moving parts. It was.

  Therefore, the present invention provides a transparent flat plate detection system that can easily and accurately detect a transparent flat plate, and more specifically, without detecting a dedicated illumination device and detecting the transparent flat plate regardless of the mounting state. It is another object of the present invention to provide a transparent flat plate detection system that does not require calibration work or a rotation mechanism.

In order to achieve such an object, the transparent flat plate detection system according to claim 1, the region including the transparent flat plate is imaged from a predetermined angle with respect to the normal direction of the flat portion of the transparent flat plate, and a vertically polarized image and Image pickup means for picking up a horizontally polarized image, a mounting table on which the transparent plate is mounted, a reflection surface installed on the transparent plate and the optical path of the image pickup means, below the mounting table, and a plane part method of the transparent plate A light-shielding member that is disposed so as to face the image capturing unit with respect to the line and that directly irradiates light to the transparent flat plate when the transparent flat plate is arranged under illumination , a vertically polarized image, and a horizontal And an image processing device that detects a transparent flat plate based on the distribution of the vertical and horizontal polarization degrees of the vertical and horizontal polarization degree images based on the polarization image.

  Therefore, since the vertical and horizontal polarization degree images can be taken in, it becomes possible to detect the polarization change of the transparent flat plate without depending on the direction of the polarizing filter on the transparent flat plate base, and the calibration work becomes unnecessary. In addition, a rotating mechanism is not required (Problem 3). In addition, since the regular reflection light from the transparent flat plate is not incident on the image pickup means and the transmitted light obliquely incident on the transparent flat plate is used, there is no need to arrange dedicated illumination means. A transparent flat plate can be detected even under a fluorescent lamp (Problem 1). Furthermore, it is possible to detect a transparent flat plate regardless of the mounting state of the transparent flat plate, such as a mounting plate placed on the tray and a transparent flat plate placed on it, or a transparent flat plate placed on the tray as it is. (Problem 2).

The transparent flat plate detection system according to claim 2 images a region including the transparent flat plate from a predetermined angle with respect to the normal direction of the flat portion of the transparent flat plate, and picks up a vertically polarized image and a horizontally polarized image. When the transparent flat plate is arranged under illumination with respect to the image pickup means and the plane normal of the transparent flat plate, the direct irradiation light to the transparent flat plate when the transparent flat plate is arranged under illumination And a reflection member having an elevation angle so that specularly reflected light from the flat portion of the transparent flat plate enters the image pickup means, and a distribution of the vertical and horizontal polarization degrees of the vertical and horizontal polarization degree images based on the vertical and horizontal polarization images And an image processing device for detecting a transparent flat plate based on the above.

  Therefore, since the vertical and horizontal polarization degree images can be taken in, it becomes possible to detect the polarization change of the transparent flat plate without depending on the direction of the polarizing filter on the transparent flat plate base, and the calibration work becomes unnecessary. In addition, a rotating mechanism is not required (Problem 3). In addition, since the reflecting plate is arranged so as to face the imaging unit so that the specularly reflected light from the transparent flat plate enters the image imaging unit, there is no need to arrange a dedicated illumination unit, and under the fluorescent lamp Even if it exists, the detection of a transparent flat plate is enabled (Problem 1). Furthermore, it is possible to detect a transparent flat plate regardless of the mounting state of the transparent flat plate, such as a mounting plate placed on the tray and a transparent flat plate placed on it, or a transparent flat plate placed on the tray as it is. (Problem 2).

  According to a third aspect of the present invention, in the transparent flat plate detection system according to the first or second aspect, the image processing apparatus detects the position and orientation of the detected transparent flat plate.

  According to a fourth aspect of the present invention, in the transparent flat plate detection system according to the third aspect, the robot hand includes a robot hand and a robot controller that controls the robot hand, and the robot controller detects the robot hand with the detected transparent flat plate. The transparent flat plate is picked up based on the detected attitude of the transparent flat plate.

  According to a fifth aspect of the present invention, in the transparent flat plate detection system according to any one of the third and fourth aspects, the image processing apparatus determines the presence area of the transparent flat plate based on the detected position and orientation of the transparent flat plate. It determines and compares the existence area | region of two or more transparent flat plates, and detects the shape defect of a transparent flat plate.

  According to a sixth aspect of the present invention, in the transparent flat plate detection system according to any one of the third to fifth aspects, the image processing device is configured to detect the presence of the transparent flat plate based on the detected position and orientation of the transparent flat plate. And the appearance defect of the transparent flat plate is detected based on the luminance distribution of the monochrome luminance image based on the vertical polarization image and the horizontal polarization image.

According to a seventh aspect of the present invention, in the transparent flat plate detection system according to any one of the third to sixth aspects, the image processing device can detect the presence of the transparent flat plate based on the detected position and orientation of the transparent flat plate. And character and / or symbol information written on the surface of the transparent flat plate is detected based on the luminance distribution of the monochrome luminance image based on the vertical polarization image and the horizontal polarization image.
According to an eighth aspect of the present invention, in the transparent flat plate detection system according to the first aspect, the mounting table is configured in a mesh shape.
According to a ninth aspect of the present invention, in the transparent flat plate detection system according to the first aspect, the reflecting surface is a tray that receives water droplets falling from the transparent flat plate.
The invention according to claim 10 is the transparent flat plate detection system according to any one of claims 1 to 9, wherein the image pickup means includes a first region that transmits vertically polarized light and horizontally polarized light. The light that has passed through the filter having the second region that passes through is picked up by one light receiving element.

  According to the present invention, it is possible to easily and accurately detect a transparent flat plate.

1 is a schematic configuration diagram of an embodiment of a transparent flat plate detection system according to the present invention. It is a structural example (1) of an image imaging means. It is a structural example (2) of an image imaging means. It is a structural example (3) of an image imaging means. It is a structural example (4) of an image imaging means. It is an example of a region division type filter. It is a graph which shows an example of the transmittance | permeability of a transparent flat plate. It is an example of the imaging | photography result of a transparent flat plate, Comprising: (a) Monochrome luminance image, (b) Vertical / horizontal polarization degree image. It is an example of the flowchart of the image process which an image processing apparatus performs. It is an example of the image as a region extraction result of a transparent flat plate. It is an example of the image after trapezoid distortion correction. It is an example of an image in case a transparent flat plate has a chip. It is an example of an image when there is a flash on a transparent flat plate. It is an example of an image when there is no dirt on a transparent flat plate. It is an example of an image when there is dirt on a transparent flat plate. It is a schematic block diagram of other embodiment of the transparent flat plate detection system which concerns on this invention. It is a graph which shows an example of the reflectance of a transparent flat plate. It is another example of the imaging | photography result of a transparent flat plate, Comprising: (a) Monochrome luminance image, (b) Vertical / horizontal polarization degree image. It is an example of the conventional transparent body detection system. It is an example of the conventional surface inspection apparatus.

  Hereinafter, a configuration according to the present invention will be described in detail based on the embodiment shown in FIGS.

(Transparent flat plate detection system)
<First embodiment>
The transparent flat plate detection system 1 according to the present embodiment images a region including the transparent flat plate 114 from a predetermined angle with respect to the normal direction of the plane portion of the transparent flat plate 114, and picks up a vertically polarized image and a horizontally polarized image. Image pickup means (camera 12), a mounting table 113 on which the transparent flat plate 114 is placed, a reflection surface 111 placed on the optical path of the transparent flat plate 114 and the image pickup means, below the mounting table 13, and a transparent flat plate A light-shielding plate 102 that is disposed so as to face the image capturing unit with respect to the plane normal of 114 and shields regular reflection light from the plane part of the transparent flat plate 114 from entering the image capturing unit; The image processing apparatus 13 detects the transparent flat plate 114 based on the distribution of the vertical and horizontal polarization degrees of the vertical and horizontal polarization degree images based on the image and the horizontal polarization image.

  FIG. 1 is a schematic configuration diagram of a transparent flat plate detection system 1. The transparent flat plate detection system 1 includes a transparent flat plate placement unit 11, a camera 12 capable of capturing a monochrome luminance image and a vertical / horizontal polarization degree image, an image processing device 13, a monitor 14, a robot controller 15, and a robot hand 16. It is configured.

  The transparent flat plate detection system 1 is installed indoors, for example, in a factory or the like, and is arranged under room illumination such as a fluorescent lamp 101. In addition, the mounting table 113 of the transparent flat plate mounting unit 11 and the ground are arranged in parallel, and the camera 12 images the transparent flat plate 114 with an elevation angle of a predetermined angle described later from the normal direction of the mounting table 113. Are arranged to be. Further, a light shielding plate 102 is disposed between the camera 12 and the room lighting (fluorescent lamp 101) so that the room lighting on the transparent flat plate 114 is not directly irradiated. However, partial light shielding is sufficient for the fluorescent lamp 101 directly above. As the light shielding plate 102, for example, a black cloth or the like attached to a plastic plate may be used. However, the light shielding plate 102 is not limited to this as long as it has a light shielding property.

  By disposing the light shielding plate 102, unnecessary reflected light on the surface of the transparent flat plate 114 is removed, and the camera 12 picks up the transparent flat plate transmitted light incident from the lower side of the mounting table 113 and is generated when it is transmitted. Since the change in the polarization state can be detected without being buried in the regular reflection light, the detection accuracy of the transparent flat plate 114 is improved.

  The transparent flat plate mounting part 11 has a mounting surface 113 on which the transparent flat plate 114 is mounted and a reflective surface 111 on the other side of the mounting table 113 when viewed from the camera 12 side. The reflection surface 111 may be a tray or the like, and may have a role of receiving wrinkles from the transparent flat plate 114 that has undergone a cleaning process or the like.

  Further, the mounting table 113 has a mesh structure, and has a mesh occupation ratio that allows the light reflected by the reflecting surface 111 to sufficiently pass through the transparent flat plate 114. Specifically, an occupation ratio of about 5% of the transparent flat plate region is desirable. In addition, it is desirable that each mesh is thin, and it is desirable that the mesh be 5% or less with respect to the size of the transparent flat plate 114. With such a size, the area of the transparent flat plate 114 through which polarized light passes increases and the background area also increases, so that the edge detection accuracy of the transparent flat plate 114 is improved.

  The camera 12 is a camera that can capture a luminance monochrome image and a vertical / horizontal polarization degree image. Each pixel signal forming each two-dimensional image is output from the sensor side in the camera 12 to the image processing device 13.

  The image processing apparatus 13 converts each pixel signal from the camera 12 into A / D conversion by binarizing or multileveling the A / D converter 131, and digitally converting the A / D converter 131 into 2 Memory 132 for storing data that has been digitized or multi-valued, a display control unit 133 for display control of the monitor 14, a communication control unit (not shown) that performs communication control of control signals to the robot controller 15, a CPU 135, etc. It is comprised by. The CPU 135 performs various image processing and calculations according to a program stored in a ROM (not shown) or the like.

  In addition, the image processing device 13 detects the position, orientation, size (existing region), and the like of the transparent flat plate 114 using the light / dark distribution in the image obtained from the camera 12, that is, the image of the data stored in the memory 132. Perform the process.

  In addition, a process of displaying results such as the position and orientation of the obtained transparent flat plate 114 on the monitor 14 through the display control unit 133 is performed. Further, a process of transmitting a control signal obtained from the result of the position and posture of the transparent flat plate 114 to the robot controller 15 is performed.

  The monitor 14 is a display device such as an LCD or a CRT, and the robot controller 15 performs drive control of the robot hand 16 in accordance with a control signal from the image processing device 13. The robot hand 16 picks up the transparent flat plate 114 placed on the upper surface of the mounting table 113 according to the drive control of the robot controller 15 and stores it in a storage unit such as a tray (not shown).

(Image capturing means)
Next, a configuration of a camera as an image capturing unit that captures a vertical / horizontal polarization degree image will be described. The camera 12 acquires an ambient image including a transparent flat plate 114 having, for example, megapixel-sized pixels, using an imaging device such as a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) as a light receiving device. The camera 12 in the transparent flat plate detection system 1 according to the present embodiment can acquire a polarization image in addition to a luminance image. The camera 12 for forming this polarized image will be described below.

<First Embodiment of Image Imaging Unit>
As shown in FIG. 2, the camera 12 has a polarizing filter 20a disposed at a position where the vertically polarized light is transmitted and takes a vertically polarized image, and a polarizing filter 20b disposed at a position where the horizontally polarized light is transmitted. And a camera for taking a horizontally polarized image. According to this camera 12, there is no time lag for rotating the polarization filter as in the conventional camera, and a vertically polarized image and a horizontally polarized image can be taken simultaneously.

  In addition, unlike the stereo system, two cameras can be arranged close to each other. In recent years, there is a high need for miniaturization of equipment, so that the camera 12 shown in FIG. 2 is further reduced in size by using a single light receiving element via a lens array and a polarizer filter array as shown in FIG. It is also preferable to use a camera 12 having a configuration for imaging.

  FIG. 3 shows a schematic configuration diagram of the optical system 21 of the camera 12. The optical system 21 has two optical systems for capturing a vertically polarized image and a horizontally polarized image. A lens array 22, a light shielding spacer 23, a polarizing filter 24, a spacer 25, and a solid-state imaging unit 26 are laminated. Is formed.

  The lens array 22 has two lenses 28a and 28b. The two lenses 28a and 28b are formed of a single lens made of, for example, an aspheric lens having the same shape independent from each other, and are arranged on the same plane with the optical axes 27a and 27b being parallel. Here, assuming that the direction parallel to the optical axes 27a and 27b of the lenses 28a and 28b is the Z axis, the direction perpendicular to the Z axis is the X axis, and the direction perpendicular to the Z axis and the X axis is the Y axis, the lenses 28a and 28b. Are arranged on the same XY plane.

  The light-shielding spacer 23 has two openings 29a and 29b, and is provided on the side opposite to the subject side with respect to the lens array 22. The two openings 29a and 29b are penetrated with a predetermined size centering on the optical axes 27a and 27b, respectively, and the inner wall surface is subjected to antireflection treatment of light by blacking, roughing or matting.

  The polarizing filter 24 includes two polarizer regions 30a and 30b having different polarization planes by 90 degrees, and is provided on the side opposite to the lens array 22 with respect to the light shielding spacer 23. The two polarizer regions 30a and 30b are provided in parallel with the XY plane around the optical axes 27a and 27b, respectively. The polarizer regions 30a and 30b convert non-polarized light whose electromagnetic field vibrates in an unspecified direction into linearly polarized light by transmitting only vibration components in the direction along the polarization plane.

  The spacer 25 is formed in a rectangular frame shape having an opening 31 through which regions corresponding to the polarizer regions 30 a and 30 b of the polarizing filter 24 pass, and is provided on the opposite side of the light shielding space 23 with respect to the polarizing filter 24. Yes.

  The solid-state image pickup unit 26 has two solid-state image pickup elements 33 a and 33 b mounted on a substrate 32 having a signal processing unit, and is provided on the opposite side of the polarization filter 24 with respect to the spacer 25. The imaging areas where the subject images are actually formed by the two solid-state imaging devices 33a and 33b are provided on the same plane parallel to the XY plane with the optical axes 27a and 27b as the centers. The solid-state imaging devices 33a and 33b do not have a color filter when performing monochrome sensing, and may be disposed at the previous stage when sensing a color image.

<Second Embodiment of Image Imaging Unit>
In addition, as shown in FIG. 4, an image is picked up by one imaging lens (a plurality of lenses may be coaxially arranged), and a vertical polarization image and a horizontal polarization image are separated at the rear stage of the lens, and the degree of vertical and horizontal polarization from each image. It is also preferable to use a camera 12 having a configuration for forming an image.

  This camera 12, as shown in FIG. 4, captures a vertically polarized image and a horizontally polarized image, as shown in FIG. 4, a half mirror box 34 having 1: 1 transparency, a mirror 35, a vertical polarization filter 36, and a horizontal A CCD 38 that captures a field image through a polarizing filter 37, a vertical polarization filter 36, and a CCD 39 that captures a field image through a horizontal polarization filter 37 are provided. In the camera 12 of the first embodiment, it is possible to simultaneously capture a vertically polarized image and a horizontally polarized image, but parallax occurs. On the other hand, since the camera 12 according to the second embodiment captures images through the same imaging optical system (lens), no parallax occurs. Therefore, the detection area can be small, and processing such as parallax deviation correction is not necessary.

  Instead of the half mirror, a polarization beam splitter that is a prism that reflects laterally polarized light and transmits longitudinally polarized light may be used. When the polarizing beam splitter is used, the vertical polarizing filter 36 and the horizontal polarizing filter 37 are not necessary, so that the optical system can be simplified and the light utilization efficiency can be improved.

<Third embodiment of image pickup means>
In addition, as shown in FIG. 5, a single imaging lens (a plurality of lenses may be coaxially arranged) is used, and a polarizer region that passes only vertically polarized light and a polarizer region that allows only horizontally polarized light to pass through the rear of the lens. It is also preferable to use the camera 12 having a configuration in which the region-divided filter 24 is disposed. Here, as the polarizer region, a region-divided polarizer filter with a clear boundary can be formed by a wire grid method formed with a metal fine concavo-convex shape or an auto-cloning photonic crystal method.

  In the camera 12 of the second embodiment, the optical system is enlarged in order to split the vertically polarized image and the horizontally polarized image into prisms, and two light receiving elements are required. On the other hand, the camera 12 of the third embodiment can acquire a laterally polarized image and a longitudinally polarized image with an optical system coaxial with the imaging lens.

  Here, the configuration of the area division type filter is not limited to the one corresponding to the pixels of the light receiving element, and for example, a configuration as shown in FIG. 6 is also preferable. In FIG. 6, squares arranged in the vertical and horizontal directions indicate the light receiving portions (light receiving element array 40) of the respective light receiving elements, and two types of diagonal bands indicate two types of polarizing filter regions 41 and 42 in the vertical and horizontal directions. Each of the filter regions 41 and 42 has a width of one pixel, that is, a width of one light receiving element in the horizontal direction, and the inclination of the boundary line of the region is 2, that is, two pixels in the vertical direction while proceeding by one pixel in the horizontal direction. It has the shape of an oblique band with a changing angle.

  By combining such a special filter arrangement pattern and signal processing, it is possible to reproduce each filter transmission image on the entire screen even if the alignment accuracy when joining the image sensor array and the area division filter is not sufficient Such an image pickup apparatus can be realized at low cost.

  As described above, the camera 12 in the transparent flat plate detection system 1 according to the present embodiment can acquire a polarization image. The camera 12 preferably acquires a transparent flat plate image in real time, and the acquired transparent flat plate image is supplied to the image processing device 13.

(Transparent flat plate detection)
In particular, the camera 12 in the transparent flat plate detection system 1 according to the present embodiment uses a change in the polarization state of light obliquely transmitted through the transparent flat plate 114. The light incident on the parallel flat plate has a difference in transmittance between the vertical component (P component) and the horizontal component (S component).

  Specifically, as shown in FIG. 7, the S component monotonously decreases, whereas the P component has a characteristic of decreasing after increasing once. The example shown in FIG. 7 shows the transmittance characteristics of light incident on a glass plate having a refractive index of 1.5 at an incident angle θ.

  The transparent flat plate detection system 1 uses such a change in transmittance of the P component and the S component. Here, as can be seen from FIG. 7, the difference between P and S becomes large when the elevation angle is about 70 degrees, and the transmittance of the P component is sufficiently high (90% or more). It is preferable to set in the range of 50 to 70 degrees.

  As described above, the camera 12 can shoot a vertical / horizontal polarization degree image, and has gradation in the polarization direction from the horizontal component (S component) to the vertical component (P component) (for example, 256 gradations). ). In other words, a dark portion is displayed when P component light is incident, and a bright portion is displayed when S component light is incident.

  An example of the result of photographing by the camera 12 is shown in FIG. FIG. 8A shows an example of a monochrome luminance image, and FIG. 8B shows an example of a vertical and horizontal polarization degree image.

  As shown in FIG. 8B, the vertical and horizontal polarization degrees of the background portion that does not pass through the transparent flat plate 114 are bright portions. On the other hand, the vertical and horizontal polarization degrees of the region that has passed through the transparent flat plate 114 are attenuated because the S component is reflected and attenuated on the lower side of the transparent flat plate, whereas the P component is transmitted as it is. Is emphasized, and the portion of the transparent flat plate is shifted toward the dark portion. On the other hand, as shown in FIG. 8A, in the monochrome luminance image, only the edge portion of the transparent flat plate 114 is slightly white, and it is difficult to separate from the mounting table 113 in image processing.

  As described above, when the longitudinal / horizontal polarization degree image is used, the contrast between the transparent flat plate region and other portions can be clearly obtained, so that the transparent flat plate region can be extracted by the image processing flow described below.

(First embodiment of transparent flat plate region extraction flow)
FIG. 9 shows a processing flow executed by the image processing apparatus 14 of the transparent flat plate detection system 1 when detecting the transparent flat plate transmitted light as shown in FIG.

  First, the vertical and horizontal polarization degree imaging is performed by the camera 12 (step S101), and the vertical and horizontal polarization degree signals of each pixel obtained by the imaging are A / D converted and digitized by the A / D conversion unit 141 (step S102). ).

  Next, a threshold value for binarization processing is set according to the camera elevation angle (step S103a), and binarization is performed (step S103b). Each binarized pixel value is stored as image data in the memory 132 (step S104).

  Next, in order to identify each dark part, a bright part lump (an example of the extraction result is shown in FIG. 10) is labeled (step S105), and a bright part lump having a predetermined area or more is detected. Further, the center of gravity and the second moment are calculated for the bright part block having a predetermined area or more, and the center of gravity of the obtained bright part block is obtained as the position of the transparent flat plate 114. The CPU 135 executes processing for obtaining the posture (step S106).

  Thus, first, the transparent flat plate 114 can be detected in the image processing by detecting a cluster of bright portions having a predetermined area or more. Further, the position and orientation can be obtained by calculating the center of gravity and the second moment for the cluster of bright portions having a predetermined area or more.

  After the above detection process, the CPU 135 executes a process of transmitting a control signal obtained from the position and orientation data of the transparent flat plate 114 to the robot controller 15, and the robot controller 15 is driven and controlled, whereby the transparent flat plate 114 is controlled. Then, it is picked up by the robot hand 16 in conformity with the above-mentioned posture, and aligned and packed in a tray (not shown) (step S107). This clogging is repeated until completion for all the detected transparent flat plates 114 (steps S108 and S109).

Note that the vertical and horizontal polarization degrees in the above processing are calculated as follows. The camera 12 acquires the vertical polarization component (P), the horizontal polarization component (S), and polarized RAW image data including the vertical polarization component (P) and horizontal polarization component (S). The vertical / horizontal polarization degree information processing unit uses the acquired vertical polarization component (also referred to as P polarization component or P component) and the horizontal polarization component (referred to as S polarization component or S component) to create a vertical / horizontal polarization degree image and vertical / horizontal polarization. Calculate the degree. Here, the vertical and horizontal polarization degree image data is obtained by the following equation (1).
Vertical / horizontal polarization degree = (P-polarized component−S-polarized component) / (P-polarized component + S-polarized component) (1)

  Further, when picking up with the robot hand 16, it may be difficult to determine the center position or the like in an oblique image (trapezoidal image) as shown in FIG. 10, so that for example, trapezoidal distortion correction processing such as affine transformation is performed. It is also preferable to make it. Thereby, the accuracy as shown in FIG. 10 can be improved by converting the image shown in FIG. 10 into an image seen from directly above as shown in FIG.

  Further, when calculating the position and orientation, a template may be prepared in advance, and the position and orientation may be calculated based on the template. For example, the transparent flat plate is not limited to the rectangular shape as shown in FIG. 8, and for example, an image rotated every other degree is prepared in advance as a template, and the rotation state based on the template is prepared. An attitude corresponding to the above may be calculated.

  Note that other image processing by the image processing device 13, that is, each image processing such as binarization processing, labeling processing, center of gravity and second moment calculation processing, may be based on a known or new algorithm, and is particularly limited. Therefore, detailed description is omitted. The threshold used for each image process may be set according to the camera elevation angle θ and the size and shape of the transparent flat plate 114.

  As described above, according to the transparent flat plate detection system 1 according to the present embodiment, a change in the polarization state of transmitted light that is obliquely incident on the transparent flat plate 114 from the reflection surface 111 is used, and unnecessary light due to specular reflection light is used. Since the structure is cut off, the contrast of the portion where the transparent flat plate 114 exists can be increased, and the transparent flat plate can be detected. Thereby, since the vertical and horizontal polarization degree images can be taken in, it becomes possible to detect the polarization change of the transparent flat plate 114 without depending on the direction of the polarizing filter on the transparent flat plate base, and the calibration work becomes unnecessary. In addition, a rotating mechanism is not required (Problem 3). Further, since the regular reflection light from the transparent flat plate is not incident on the image pickup means and the transmitted light of the transparent flat plate 114 is used, there is no need to arrange a dedicated illumination means, and a fluorescent lamp Even under 101, the transparent flat plate 114 can be detected (Problem 1). Further, it is possible to detect the transparent flat plate 114 in a state where the mounting table 113 is installed on the tray and the transparent flat plate 114 is arranged thereon, or the transparent flat plate is arranged on the tray as it is (Problem 2).

  Further, the position and orientation of the transparent flat plate 114 detected by image processing can be easily and accurately obtained. Furthermore, the transparent flat plate 114 can be accurately picked up by the robot hand 16 based on the obtained position and posture of the transparent flat plate 114.

(Defect inspection)
Moreover, it is also preferable that the transparent flat plate detection system 1 inspects for the presence or absence of defects such as chipping and flashing in conjunction with the detection of the position and orientation of the transparent flat plate 114.

  First, similarly to the above, the existence area of the transparent flat plate 114 is specified. Here, when the transparent flat plate 114 has a defect of a chip 43, as shown in FIG. 12, the bright portion in the obtained (binary) vertical and horizontal polarization degree image is larger than the region where the transparent flat plate exists in the case of a non-defective product. Get smaller. Further, if there is a defect of the flash 44 on the transparent flat plate 114, as shown in FIG.

  Therefore, since the number of pixels in the existing region of the transparent flat plate 114 in the case of a non-defective product is known, the normal range defined by the upper limit value and the lower limit value of the number of pixels is used as a reference for determining the presence / absence of a defect from the number of pixels. After specifying the existence area of the transparent flat plate 114, the number of pixels in the bright part of the transparent flat plate 114 is counted. If the count value is within the normal range, it is determined that there is no defect, and the count value is within the normal range. If the count value is smaller than the lower limit value of the normal range, it can be determined that there is a defect 43 defect. As a result, it is possible to detect a shape defect such as chipping or flashing that may occur in the transparent flat plate 114, and to determine whether the product is good or defective.

(Transparent object inspection)
The transparent flat plate detection system 1 is also preferably used for inspecting a transparent foreign substance in a bottle for inspecting the presence or absence of a transparent foreign substance inside the translucent bottle. That is, when there is a transparent foreign matter, the vertical and horizontal polarization degree image is a dark or bright block of the transparent foreign matter. Therefore, the presence / absence of a transparent foreign object can be determined according to the presence / absence of a portion that appears as a lump in the image. This makes it possible to detect transparent foreign matters remaining in an empty bottle or a bottle containing a transparent liquid.

(Second embodiment of transparent flat plate region extraction flow)
Another processing flow executed by the image processing apparatus 14 of the transparent flat plate detection system 1 will be described. Unlike the first embodiment, the second embodiment of the transparent flat plate region extraction flow uses a luminance image in addition to the vertical and horizontal polarization degree images to detect defects such as dirt, scratches and cracks, and character information such as logos and marks. The image information is detected and the classification method at the time of packing is increased.

Generation of monochrome luminance information using polarization information from the camera 12 will be described. The monochrome luminance processing unit creates a monochrome image and calculates luminance information using the acquired P component and S component. Further, the monochrome luminance is obtained by generating and outputting luminance information image data according to the following equation (2).
Monochrome brightness = P polarization component + S polarization component (2)

  When inspecting the transparent flat plate 114 for defects such as dirt, scratches, and cracks, the processing flow 1 determines the position and orientation of the transparent flat plate 114 and specifies the region where the transparent flat plate 114 exists.

  Here, when there is no defect in the transparent flat plate 114, the existing area on the image obtained by the monochrome luminance image is an image having a low contrast as shown in FIG. On the other hand, if there is a defect (for example, dirt 45) on the transparent flat plate, the part corresponding to the dirt 45 becomes darker than the surroundings as shown in FIG. High contrast image.

  Therefore, in the existence area on the luminance image, it is determined whether the size and degree of change of the luminance distribution of the monochrome luminance image are within a normal range, that is, the number of pixels equal to or less than a predetermined brightness. Measurement may be performed, and the presence or absence of a defect may be determined according to the measurement result.For example, if the number of pixels of the measurement result is equal to or greater than a predetermined inspection threshold, it is determined that there is a defect; Can be determined. As a result, it is possible to detect defects in appearance such as dirt, scratches, and cracks that can occur on the transparent flat plate, and it is possible to discriminate between non-defective products and defective products.

  In addition, after specifying the position and orientation of the transparent flat plate 114 in the vertical and horizontal polarization degree images, based on the size and degree of change of the luminance distribution changing portion of the monochrome luminance image, a logo or a mark written on the transparent flat plate surface, etc. It is also preferable to detect character information and symbol information. Thereby, picking of the transparent flat plate 114 based on character information or symbol information is also possible.

(Transparent flat plate detection system)
<Second Embodiment>
Hereinafter, a transparent flat plate detection system according to another embodiment of the transparent flat plate detection system according to the present invention will be described. The transparent flat plate detection system 1 according to the present embodiment images a region including the transparent flat plate 114 from a predetermined angle with respect to the normal direction of the plane portion of the transparent flat plate 114, and picks up a vertically polarized image and a horizontally polarized image. The image pickup means (camera 12) to be arranged is opposed to the image pickup means with respect to the plane normal of the transparent flat plate 114, and the specularly reflected light from the flat portion of the transparent flat plate 114 enters the image pickup means. Thus, the reflection plate 103 having an elevation angle and the image processing device 13 for detecting the transparent flat plate 114 based on the distribution of the vertical and horizontal polarization degrees of the vertical and horizontal polarization degree images based on the vertical polarization image and the horizontal polarization image are provided.

  FIG. 16 is a schematic configuration diagram of the transparent flat plate detection system 1. The transparent flat plate detection system 1 includes a transparent flat plate placement unit 11, a camera 12, an image processing device 13, a monitor 14, a robot controller 15, and a robot hand 16. The transparent flat plate detection system 1 according to the second embodiment includes a reflection plate 103 instead of the light shielding plate 102. Hereinafter, description of the same points as in the first embodiment will be omitted as appropriate.

  The transparent flat plate detection system 1 is installed indoors, for example, in a factory or the like, and is arranged under room illumination such as a fluorescent lamp 101. In addition, the mounting table 113 of the transparent flat plate mounting unit 11 and the ground are arranged in parallel, and the camera 12 images the transparent flat plate 114 with an elevation angle of a predetermined angle described later from the normal direction of the mounting table 113. Are arranged to be. Further, while preventing the indoor lighting from being directly applied to the transparent flat plate 114, light from the periphery, not direct light from the fluorescent lamp 101, is incident on the transparent flat plate 114, and the reflected light is incident on the camera 12. A reflecting plate 103 is provided at the position. However, partial light shielding is sufficient for the fluorescent lamp 101 directly above. For example, a plastic plate may be used as the reflecting plate 103.

  By disposing the reflecting plate 103, unnecessary reflected light as direct reflected light from the fluorescent lamp 101 is removed, and the camera 12 images the transparent flat plate reflected light incident from the reflecting plate 103, and is generated when the reflected light is reflected. Since the change in the polarization state can be detected without being disturbed by disturbance light such as the fluorescent lamp 101, the detection accuracy of the transparent flat plate 114 is improved.

  When using transparent flat plate reflected light as in this embodiment, the state of the lower side of the transparent flat plate 114 is not particularly limited, but it is preferable to use a material that particularly reflects the P component. Examples of the material that reflects the P component include a material that internally scatters, such as plastic. Therefore, for example, when a plastic tray or the like is disposed below the transparent flat plate 114, the contrast between the transparent flat plate 114 and the background becomes clear.

(Transparent flat plate detection)
In particular, the camera 12 in the transparent flat plate detection system 1 according to the present embodiment uses a change in the polarization state of light that is incident and reflected obliquely on the transparent flat plate 114. The light incident on the parallel plate has a difference in reflectance between the vertical component (P component) and the horizontal component (S component).

  Specifically, as shown in FIG. 17, the S component monotonously increases, whereas the P component has a characteristic of increasing once decreasing. Note that the example shown in FIG. 17 shows the transmittance characteristics of light incident on a glass plate having a refractive index of 1.5 at an incident angle θ.

  The transparent flat plate detection system 1 utilizes such reflectance changes of the P component and the S component. Here, as can be seen from FIG. 17, the difference between P and S is large when the elevation angle is about 70 degrees, and the reflectance of the S component is high (20% or more). It is preferable to set a range of 70 degrees.

  As described above, the camera 12 can shoot a vertical / horizontal polarization degree image, and has gradation in the polarization direction from the horizontal component (S component) to the vertical component (P component) (for example, 256 gradations). ). That is, a dark portion is displayed when S component light is incident, and a bright portion is displayed when P component light is incident.

  An example of the result of photographing by the camera 12 is shown in FIG. FIG. 18A shows an example of a monochrome luminance image, and FIG. 18B shows an example of a vertical / horizontal polarization degree image.

  As shown in FIG. 18B, when a background is selected such that the vertical and horizontal polarization degrees of the background portion that does not pass through the transparent flat plate 114 are dark portions, the vertical and horizontal polarization degrees of the region that reflects the transparent flat plate 114 is , Shift to the bright part. On the other hand, as shown in FIG. 18A, in the monochrome luminance image, only the edge portion of the transparent flat plate 114 becomes slightly white, and it is difficult to separate from the mounting table 113 in the image processing.

  As described above, when the vertical / horizontal polarization degree image is used, a portion corresponding to the region where the transparent flat plate 114 exists in the image obtained by imaging becomes a bright portion or a dark portion, and the contrast with the background becomes high. The flow can detect the transparent flat plate region, and further detect the position, posture, size, and the like of the transparent flat plate.

  As described above, according to the transparent flat plate detection system 1 according to the present embodiment, a change in the polarization state of transmitted light that is obliquely incident on the transparent flat plate 114 from the reflection surface 111 is used, and unnecessary light due to specular reflection light is used. Since the structure is cut off, the contrast of the portion where the transparent flat plate 114 exists can be increased, and the transparent flat plate 114 can be detected. Thereby, since the vertical and horizontal polarization degree images can be taken in, it becomes possible to detect the polarization change of the transparent flat plate 114 without depending on the direction of the polarizing filter on the transparent flat plate base, and the calibration work becomes unnecessary. In addition, a rotating mechanism is not required (Problem 3). Further, since the regular reflection light from the transparent flat plate is not incident on the image pickup means and the transmitted light of the transparent flat plate 114 is used, there is no need to arrange a dedicated illumination means, and a fluorescent lamp Even under 101, the transparent flat plate 114 can be detected (Problem 1). Further, it is possible to detect the transparent flat plate 114 in a state where the mounting table 113 is installed on the tray and the transparent flat plate 114 is arranged thereon, or the transparent flat plate is arranged on the tray as it is (Problem 2).

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, the detection target by the transparent flat plate detection system according to the present invention is not limited to the transparent flat plate as long as it can be detected by the above-described processing, and can be applied to other transparent bodies. The material of the transparent body is not limited to plastic, glass, etc., but may be other materials.

DESCRIPTION OF SYMBOLS 1 Transparent flat plate detection system 11 Transparent flat plate mounting part 12 Camera (image pick-up means)
13 Image processing device 14 Monitor 15 Robot controller 16 Robot hand 20a, 20b Polarizing filter 21 Optical system 22 Lens array 23 Light blocking spacer 24 Polarizing filter 25 Spacer 26 Solid imaging unit 27a, 27b Optical axis 28a, 28b Lens 29a, 29b Opening 30a , 30b Polarizer region 31 Opening 32 Substrate 33a, 33b Solid-state imaging device 34 Half mirror box 35 Mirror 36 Vertical polarization filter 37 Horizontal polarization filter 38, 39 CCD
40 Light-receiving element array 41 Polarizing filter region (vertical)
42 Polarizing filter area (horizontal)
43 chip 44 beam 45 dirt 101 fluorescent lamp 102 light-shielding plate 103 reflecting plate 111 reflecting surface 113 mounting table 114 transparent plate 131 A / D conversion unit 132 memory 133 display control unit 135 CPU

JP 2002-98650 A JP-A-9-166552

Claims (10)

An image capturing unit that captures an image of a region including the transparent flat plate from a predetermined angle with respect to a plane normal direction of the transparent flat plate, and picks up a vertically polarized image and a horizontally polarized image;
A mounting table on which the transparent flat plate is mounted;
On the optical path of the transparent plate and the image pickup means, a reflective surface installed on the lower side of the mounting table,
It is arranged so as to face the image pickup means with respect to the plane normal of the transparent flat plate , and when the transparent flat plate is placed under illumination, direct illumination light to the transparent flat plate is shielded A shading member to be
A transparent flat plate detection system comprising: an image processing device that detects the transparent flat plate based on a vertical and horizontal polarization degree distribution of a vertical and horizontal polarization degree image based on the vertical polarization image and the horizontal polarization image. An image capturing unit that captures an image of a region including the transparent flat plate from a predetermined angle with respect to a plane normal direction of the transparent flat plate, and picks up a vertically polarized image and a horizontally polarized image;
It is arranged so as to face the image pickup means with respect to the plane normal of the transparent flat plate, and when the transparent flat plate is placed under illumination, direct illumination light to the transparent flat plate is shielded And a reflection member having an elevation angle so that specularly reflected light from the flat portion of the transparent flat plate is incident on the image pickup means,
A transparent flat plate detection system comprising: an image processing device that detects the transparent flat plate based on a vertical and horizontal polarization degree distribution of a vertical and horizontal polarization degree image based on the vertical polarization image and the horizontal polarization image.   3. The transparent flat plate detection system according to claim 1, wherein the image processing device detects the position and orientation of the detected transparent flat plate. A robot hand and a robot controller for controlling the robot hand;
The robot controller moves the robot hand based on the detected position of the transparent flat plate and picks up the transparent flat plate based on the detected posture of the transparent flat plate. The transparent flat plate detection system described. The image processing device determines the presence area of the transparent flat plate based on the detected position and posture of the transparent flat plate,
The transparent flat plate detection system according to claim 3, wherein a shape defect of the transparent flat plate is detected by comparing existing regions of the two or more transparent flat plates. The image processing device determines the presence area of the transparent flat plate based on the detected position and posture of the transparent flat plate,
6. The transparent flat plate according to claim 3, wherein an appearance defect of the transparent flat plate is detected based on a luminance distribution of a monochrome luminance image based on the vertical polarization image and the horizontal polarization image. Detection system. The image processing device determines the presence area of the transparent flat plate based on the detected position and posture of the transparent flat plate,
The character and / or symbol information written on the surface of the transparent flat plate is detected based on a luminance distribution of a monochrome luminance image based on the vertical polarization image and the horizontal polarization image. The transparent flat plate detection system according to any one of the above. The transparent flat plate detection system according to claim 1, wherein the mounting table is configured in a mesh shape. The transparent flat plate detection system according to claim 1, wherein the reflection surface is a tray that receives water drops falling from the transparent flat plate. The image pickup means picks up light that has passed through a filter having a first region that transmits vertically polarized light and a second region that transmits horizontally polarized light with a single light receiving element. The transparent flat plate detection system according to any one of claims 1 to 9.