Method and inspection device for material testing of workpieces in a production and / or transfer line

Abstract

The invention relates to a method for material testing of workpieces (2) in a production and / or transport line and to an inspection device (10) suitable for carrying out the material testing. During material testing, a workpiece (2) is conveyed along a conveying direction (4) in a conveying plane (3) of a production and / or conveying device (1), an optical inspection device (11) is positioned at at least one previously identified potential defect position (30) of the workpiece (2), and at least one image is captured by the optical inspection device (11) at the potential defect position (30) of the workpiece (2, 102). According to the invention, the workpiece (2) is moved during the material test and the optical inspection device (11) is moved together with the workpiece (2), the at least one image being taken by the optical inspection device (11) during the movement of the workpiece (2, 102) and the optical inspection device (11).

Description

Technical Field

[0001] The present invention relates to a method for material testing of a workpiece in a production and / or conveyor line, and to an inspection device for material testing of a workpiece that is conveyed in a production and / or conveyor line at a conveying speed along a conveying plane by means of a production and / or conveying device. Background Technology

[0002] In a method for material testing of a workpiece, the workpiece is conveyed along a conveying direction in the conveying plane of a production and / or conveying device. This method can be performed using a properly equipped inspection device with at least one optical inspection device, hereinafter also referred to simply as an inspection device. For this purpose, it is specified that the optical inspection device is positioned (in the sense of "facing") at at least one previously identified potential defect location on the workpiece. A potential defect location is a location identified on the workpiece where a defect to be inspected by material testing may exist. The purpose and / or use of material testing is to identify and / or classify defects in order to determine whether a (related) defect actually exists, resulting in the workpiece being rejected as a nonconforming product and / or reworked.

[0003] During the execution of this method, an inspection device captures at least one image (an image of the potential defect location) at the location of a potential defect in the workpiece. Typically, several potential defect locations exist on the workpiece, and each potential defect location must be inspected and evaluated through material testing. For this purpose, the optical inspection device can be moved sequentially to each potential defect location, and material testing can be performed specifically by capturing one or more images of these defect locations. In this document, an image should be understood as an image of the defect location.

[0004] For example, CN 109632828 B describes a system and method for re-inspecting defects in flat glass. In automated online inspection, surface inspection and re-inspection use the same coordinate system. The precise positioning of the re-inspection head is based on the coordinates provided by the surface inspection. The re-inspection identifies individual defects. The re-inspection head is moved to a defect location, where several images of a single glass layer are selectively taken.

[0005] The disadvantage of the described re-inspection method is that the flat glass or workpiece (in the conveyor or production line) must remain stationary during surface inspection and subsequent re-inspection. The workpiece does not move during re-inspection and imaging.

[0006] Modern production systems, such as those used in TFT or flat glass production, are achieving increasingly shorter unit production times. A 10-second cycle time per piece is quite common. Conventional inspection methods, as described above, where workpieces are stopped and inspected (re-inspection), reach their technical limits at such cycle times. A significant portion of the workpiece cycle time is spent on transfers. This accounts for approximately 60% to 70% of the available time in the cycle. Therefore, the available standby time for re-inspection is correspondingly 3 to 4 seconds. During this time, one to two re-inspections can be performed. If a larger number of potential defects need to be inspected, the standby time must be extended (thus extending the cycle time) to perform thorough inspection tasks. This is disadvantageous and generally unacceptable in production equipment because it reduces output. Summary of the Invention

[0007] The purpose of this invention is to provide a method for performing material testing in production and / or conveyor lines, which allows for more material testing operations to be performed within the available cycle time.

[0008] According to the present invention, this problem is solved by a material testing method and an inspection device for material testing, the proposed method being performed using the inspection device.

[0009] Specifically, it is specified that during material testing, the workpiece is moved (uniformly according to a preferred embodiment of the invention), and the optical inspection device moves together with the workpiece (moving with the same uniform motion as the workpiece according to a preferred embodiment of the invention), wherein at least one image is captured by the optical inspection device during the movement of the workpiece and the inspection device. Therefore, according to the invention, it is proposed that the optical inspection device moves synchronously with the workpiece, and images are captured during the synchronous movement of the workpiece and the inspection device. Thus, according to the invention, material testing is performed during the movement of the workpiece. By utilizing not only the stationary time but also the transport time within the cycle time, the number of possible inspection processes (re-inspections) can be increased under the same transport parameters and cycle time without extending the stationary time, typically increasing to 5 to 10 inspection processes, instead of being limited to 1 or 2 inspection processes during the stationary time.

[0010] Therefore, according to one embodiment of the proposed method, the optical inspection device can be positioned sequentially at at least two previously identified potential defect locations on the workpiece, preferably at at least three or four potential defect locations, and particularly preferably at up to at least five to ten defect locations. This means that each optical inspection device (and possibly multiple inspection devices) of an inspection apparatus (inspection system) is positioned at said potential defect location. By utilizing the transport time during movement according to the invention, sufficient time can be allocated to complete this operation.

[0011] In one embodiment of the invention, an imaging unit (camera) with a microscope can be used as an optical inspection device. This allows for the acquisition of high-resolution images of the locations of potential defects in the workpiece, thereby enabling the accurate detection and classification of defect locations, such as material inclusions (e.g., bubbles or trapped particles), surface defects (e.g., unevenness) or damage (e.g., scratches) from the production process.

[0012] According to another preferred embodiment of the invention, at least two images can be taken for each potential defect location on the workpiece. According to the invention, this can be done during the movement of the workpiece and the optical inspection apparatus, such that the absolute spatial positions (relative to the stationary conveyor belt) of the workpiece and the inspection apparatus are different for each image, but the relative phase between the workpiece and the inspection apparatus remains constant or the same.

[0013] In a particular embodiment of the invention, during the capture of multiple images of the potential defect location, the orientation of the inspection device relative to a plane parallel to the moving workpiece surface remains unchanged (i.e., according to the invention, the inspection device moves together with the conveyed workpiece with the same movement), wherein the distance between the workpiece or workpiece surface and the inspection device changes, preferably along a direction perpendicular to the workpiece surface. Therefore, when the optical axis of the optical inspection device is perpendicular to the workpiece surface and the potential defect location is located within the optical axis of the optical inspection device, the potential defect location on the workpiece surface is always at the same image location in the images captured by the inspection device. According to one embodiment of the proposed method, the optical axis of the optical inspection device can be oriented perpendicular to the workpiece surface at the potential defect location.

[0014] The reason for moving the inspection device along a direction perpendicular to the workpiece surface is that the imaging of the inspection device must be performed with a very short exposure time to avoid motion blur. The term "very short exposure time" is used when the movement of the workpiece and the inspection device during the exposure time is negligible, so that no motion blur will appear in the captured image.

[0015] This requires imaging with good illumination and a large aperture imaging optics for the inspection device. The latter results in a shallow depth of field and necessitates precise adjustment of the distance between the workpiece surface and the inspection device to obtain a clear image of the workpiece surface. Maintaining such distance accuracy is difficult for workpieces transported on a conveyor line and for the inspection device that moves with them. To address this, a series (multiple) images of potential defect locations on the workpiece surface can be captured according to the invention, wherein the distance between the workpiece surface and the inspection device is gradually changed between consecutive images. The amount of distance change (“step height in step size change”) can be particularly preferably selected to correspond precisely to the depth of field range of the imaging optics. Imaging the image series in a gradually changing manner, with the distance between the workpiece surface and the inspection device approximately set to a clear image, ensures that, according to the invention, at least one image in the image series displays a clear image surface. According to a particularly preferred embodiment of this variant of the invention, 4 to 10 images can be captured in a series of multiple images.

[0016] In the case of transparent workpieces, according to another embodiment of the invention, the range of spacing variation during the capture of multiple images can be specified to correspond at least to the thickness of the transparent workpiece in the imaging direction. As a result, clear images are captured at each depth of the transparent workpiece along the recording direction. This makes it possible to identify and / or classify defects enclosed within the transparent workpiece (e.g., flat glass).

[0017] If the optical axis of the optical inspection device is not perpendicular to the surface orientation and / or the positioning of the inspection device does not place the potential defect location on the optical axis, another effect may occur if multiple images of the potential defect location are taken in a series of images at different spacings. The smaller the spacing between the workpiece and the inspection device, the smaller the area of ​​the workpiece surface shown in the image, which is slightly magnified in the image (its size is always the same). Defects not in the optical axis (i.e., the image center) move towards the image edge (and are displayed larger) as the spacing decreases. This makes it more difficult to determine the precise location of the defect on the workpiece. In another embodiment of the invention, it can be specified that the orientation of the inspection device relative to the workpiece in a plane parallel to the workpiece surface also changes during the taking of multiple images. Specifically, this can be done simultaneously and in coordination with the change in spacing between the inspection device and the workpiece. According to a particularly preferred embodiment of this variant, the relative orientation of the inspection device and the workpiece can be changed such that the potential defect location, such as the center point of the potential defect location, is always at the same image location. This is possible in a calibrated system through simple beam geometry considerations known to those skilled in the art and requiring no further explanation. Specifically, a calibrated system means that the imaging characteristics of the inspection device's optics and the distance between the workpiece and the inspection device are known. This will be explained in more detail later.

[0018] Another preferred embodiment of this variant is particularly suitable for transparent workpieces, wherein taking multiple images in an image series at different intervals between the workpiece surface and the inspection device allows for clear imaging of different planes within the workpiece. A light beam from the inspection device, striking the workpiece surface at a certain angle, is refracted according to the law of refraction (depending on the optical density of the workpiece) as it passes through the workpiece. This change in beam angle can also be calculated in the system according to the law of refraction. This is known to those skilled in the art and requires no further explanation. According to the invention, in this embodiment, it is proposed to change the relative orientation of the inspection device with respect to the workpiece in a plane parallel to the workpiece surface, such that a selected image location, such as the position of the optical axis or the location of a potential defect, follows the path of the light beam within the workpiece. This achieves particularly high accuracy in defect location identification, even in transparent workpieces.

[0019] According to another preferred embodiment of the invention, which can also be combined with the other embodiments described, at least one image may be taken under bright-field illumination and at least one image may be taken under dark-field illumination. If the workpiece is conveyed flat on a production and / or conveying device, incident illumination (rather than transmitted illumination through the workpiece) is preferably provided. Regardless of the type of production and / or conveying device, incident illumination is applicable to all materials (transparent and opaque), while transmitted illumination is only applicable to transparent materials. In this context, incident illumination is particularly preferred according to the invention and is also structurally easier to handle than transmitted illumination. However, in the case of (at least partially) transparent or opaque materials, the invention can also be implemented in principle by transmitted illumination.

[0020] In a simple embodiment, for example, bright-field illumination is achieved by shining light onto the workpiece such that (in the case of a reflective workpiece) at least most of the illuminated light is reflected or will be reflected into (one) of the imaging optics of the inspection apparatus. In a corresponding simple embodiment of dark-field illumination, light is shone onto the workpiece at an angle such that (in the case of a reflective workpiece) the light is not reflected or will not be reflected into (one) of the imaging optics of the inspection apparatus. In this case, irregularities or scratches on the workpiece surface cause some light to be reflected into the imaging optics by these irregularities or scratches, and these irregularities or scratches are easily identifiable in the image (as bright areas in a dark image).

[0021] Preferably, the optical inspection apparatus includes an imaging unit (preferably a camera with imaging optics, wherein, according to a preferred embodiment, the imaging optics can be designed as a microscope) and an illumination unit (preferably having bright-field illumination and dark-field illumination), wherein, according to a particularly preferred embodiment, the imaging unit and the illumination unit are fixed to each other (i.e., cannot be moved during use). This simplifies the positioning of the inspection apparatus.

[0022] Another preferred embodiment of the invention may specify that the optical inspection device is arranged on a positioning device, wherein the positioning device causes the optical inspection device to move together with the workpiece in the workpiece conveying direction as the workpiece moves. According to a preferred embodiment, the positioning device may be fixedly mounted on the production and / or conveying device. This makes it particularly easy to track the movement of the workpiece in the conveying direction using the positioning device, since the conveying plane, conveying direction, and conveying speed are predefined relative to the production and / or conveying device.

[0023] In this context, it is particularly preferred to use a SCARA robot with (at least or exactly) three rotary axes and (at least or exactly) one translational axis in a serialized motion system as the positioning device, with all axes oriented perpendicular to the transfer plane. Such a positioning device enables the execution of uniform motion with particularly high speed and repeatability in a motion plane parallel to the transfer plane. This means that the optical inspection device can be moved particularly uniformly with the uniformly moving (i.e., transferred) workpiece using the preferred positioning device.

[0024] A serial motion system means that the origin of the coordinates of subsequent motion axes depends only on the previous motion axis. This allows for the pre-configuration of a sequence of motions in a predetermined direction (i.e., the conveying direction of the workpiece in the production or conveying device) for a defined initial position in the control unit. By simultaneously adjusting the three rotational axes in uniform motion, the optical inspection device and the workpiece are moved such that the image area (within the required accuracy) at the potential defect location remains unchanged (i.e., synchronous motion is achieved). In this way, multiple images can be captured during movement and directly compared with each other. Other aspects of the possible relative motion between the workpiece and the inspection device have been described and can be easily achieved using positioning devices.

[0025] According to a preferred embodiment of the invention, the conveying speed of the workpiece along the production and / or conveyor line is known in the control device. This can be read from the interface of the production or conveying device and / or measured by a suitable sensor system in a generally known manner. Production and / or conveying devices for sensitive products are also known, which use suitable control and / or feedback control units to achieve particularly uniform and precise conveying speeds. According to the invention, such production and / or conveying devices can be used to implement the invention.

[0026] According to a particularly preferred embodiment, a SCARA robot can be fixedly mounted on the frame of a production and / or conveying device, adjacent to or above the conveying area (e.g., via transverse supports), having a first axis of rotation for rotating a first arm. A second axis of rotation is provided at the end of the first arm opposite to the first axis of rotation, rotating the second arm. A third axis of rotation is provided at the end of the second arm opposite to the second axis of rotation, on which an optical inspection device is fixed. This allows the optical inspection device to be positioned above the workpiece within an arc segment (the size of which is predetermined by the lengths of the first and second arms). The third axis of rotation allows the orientation of the optical inspection device relative to the workpiece to remain constant during workpiece movement.

[0027] According to a particularly preferred embodiment of the invention, the aforementioned third rotating axis also enables translational movement (i.e., axial movement) of the optical inspection device in the axial direction to adjust the distance between the optical inspection device and the workpiece. Since the rotating axis is preferably arranged perpendicular to the conveying plane according to the invention, the distance between the optical inspection device and the workpiece does not change during movement. In principle, translational movement can also occur along other rotating axes. This is also included in the invention. However, in a preferred embodiment, the distance between the optical inspection device and the workpiece can be adjusted via the third axis of motion. In this case, only one adjustment of the optical inspection device is required without additional movement of the weight of the first and / or second arms using corresponding actuators. This allows for simpler and less vibration-inducing adjustments.

[0028] Preferably, the optical inspection apparatus may include a spacing sensor that measures the spacing between the workpiece and the optical inspection apparatus during movement. The spacing between the workpiece and the optical inspection apparatus can be tracked during movement and thus kept constant by translational adjustment about one of the rotation axes (preferably the third rotation axis as described above). In principle, any spacing sensor can be used for this purpose.

[0029] However, according to a particularly preferred embodiment, the present invention proposes using an optical spacing sensor to measure the spacing between the workpiece and the optical inspection apparatus. This optical spacing sensor uses a confocal dispersion sensor to detect the spacing on the workpiece surface. According to the invention, such a sensor can be integrated into the optical inspection apparatus and requires very little additional installation space. Evaluation can be performed continuously even during movement, and allows for particularly rapid control that maintains the spacing within a constant range of desired accuracy throughout the movement.

[0030] The measurement principle of an optical confocal sensor is as follows: Dispersive confocal distance measurement utilizes the dispersion of white light (i.e., light of different colors) in a focusing lens, which converges the beam onto a material surface area, preferably using optically visible light in the medium wavelength range (e.g., green light). For this purpose, a white point light source is passed through a small pinhole and focused onto the workpiece by a dispersive lens (focusing lens). Dispersion causes the blue light component to focus closer to the lens, while the red light component focuses further away. The light reflected from the workpiece is decoupled from the illumination path by a beam splitter using the same lens and fed to a color-sensitive light sensor through a corresponding pinhole aperture. This filters out the portion of the light precisely focused on the workpiece surface and reflected. Spectral analysis of the reflected light allows for very precise detection of distance variations and corresponding corrections.

[0031] Therefore, the present invention also relates to an inspection apparatus for material testing of a workpiece, the workpiece being conveyed in a production and / or conveyor line at a certain conveying speed along a conveying direction in a conveying plane by means of a production and / or conveying device, the inspection apparatus having at least one optical inspection device according to claim 9. The optical inspection device is movably fixed to the production and / or conveying device by means of a positioning device, wherein the optical inspection device includes an imaging unit and an illumination unit, and at least one control unit adapted to control the positioning device and the optical inspection device, wherein the conveying direction and conveying speed of the workpiece in the production and / or conveyor line are known in the control unit. According to the invention, the control unit is adapted to move the optical inspection device together with the workpiece, during which the optical inspection device captures the at least one image.

[0032] Preferably, the movement of the workpiece in the production or conveying device and the movement of the optical inspection device are uniform. This avoids or at least reduces damage to the workpiece during transport, and also prevents or at least reduces interference when the image of the optical inspection device is being formed.

[0033] According to the present invention, the inspection device can be adapted to perform the above-described method or a portion thereof, particularly for performing the method according to any one of claims 1 to 8. If necessary, the inspection device is equipped with the described and necessary equipment components for this purpose.

[0034] According to a preferred embodiment, the imaging unit may include a microscope. This means that the optics of the imaging unit are designed to capture high-resolution images of the locations of potential defects on the workpiece.

[0035] According to another preferred embodiment of the invention, the illumination unit includes bright field illumination and / or dark field illumination. The bright field illumination and dark field illumination, which can be switched independently according to the invention, are particularly capable of capturing different images of the same potential defect location under different illumination modes, as previously mentioned, which enhances the ability to detect and classify different defects.

[0036] According to a preferred embodiment, the positioning device may be a SCARA robot having (at least or exactly) three rotary axes and (at least or exactly) one translational axis in a serial motion system, all of which are oriented perpendicular to the transfer plane.

[0037] In this implementation, the first and second motion axes, measured from the installation of the positioning device on the production and / or conveying device, can be exclusively rotary motion axes; while the third motion axis, which is (directly) fixed to the optical inspection device, can realize rotary motion as well as axial translational motion (for adjusting the distance between the inspection device and the object).

[0038] As previously mentioned, such a SCARA robot enables the inspection device to move particularly smoothly and uniformly as the workpiece moves within the production and / or conveying system. Translational adjustments along the third axis of motion are particularly advantageous because, as previously stated, this minimizes mass during height adjustments.

[0039] According to a particularly preferred embodiment, multiple optical inspection devices can be provided, each of which is sequentially fixed to the production and / or conveying device along the conveying direction with an associated positioning device. This allows for an increase in the total number of potential defect locations that can be tested in the intended conveying section.

[0040] For multiple optical inspection devices, it may be particularly advantageous to arrange them (preferably alternately) on different sides of the production and / or conveying device (on which the material to be conveyed is placed) relative to the conveying area. This means that the optical inspection devices are arranged on or near two opposite sides of the production and / or conveying device that define the conveying area transverse to the conveying direction, i.e., some optical inspection devices are arranged on one side and some on the other side. This expands the total accessible inspection area if the length of the arm of the positioning device does not cover the entire width of the workpiece transverse to the conveying direction. Furthermore, the range of motion of the optical positioning devices can be optimized such that one optical inspection device inspects each potential defect location by material testing on the half of the workpiece closest to the edge of the production and conveying device where the optical inspection device or its assigned positioning device is mounted. This minimizes the amount of movement required for each optical inspection device.

[0041] According to another alternative embodiment, a camera unit can be positioned in front of at least one optical inspection device (in the conveying direction) to capture images of workpieces in the production and / or conveyor line. These images are then evaluated in a control unit using image recognition to identify potential defect locations. This means that the potential defect locations of the workpieces are known. Due to the known conveying speed and the known relative arrangement of the camera unit with the optical inspection device, the optical inspection device can perform targeted material testing on the potential defect locations. Alternatively, in principle, the locations of potential defects on the workpieces can be determined first, and then the control unit can accordingly control the optical inspection device to move relative to these locations.

[0042] According to the present invention, the present invention can be used for material testing of any transparent or opaque workpiece, such as TFT glass, float glass, plate workpieces or other loose goods.

[0043] Further advantages, features, and possible applications of the invention will also be apparent from the following description of the embodiments and / or the drawings. All features described and / or shown in the drawings form part of the subject matter of the invention, regardless of their combination or dependence in the claims. Attached Figure Description

[0044] Figure 1 A three-dimensional view of an inspection apparatus having an optical inspection device according to an embodiment of the present invention is shown;

[0045] Figure 2 It shows Figure 1 The imaging unit of the optical inspection device shown in the inspection apparatus;

[0046] Figure 3 It shows Figure 1 The illumination unit of the optical inspection device shown in the inspection apparatus;

[0047] Figure 4 A three-dimensional view of an inspection apparatus having two optical inspection devices according to another embodiment of the present invention is shown;

[0048] Figure 5 The diagram schematically illustrates an exemplary use of an optical inspection apparatus, showing the optical path to a defect location 30 and the captured image.

[0049] Figure 6 The optical path of defect location 30 according to another exemplary embodiment is schematically shown. Detailed Implementation

[0050] The embodiments of the invention shown in the accompanying drawings illustrate the inspection apparatus according to the invention through illustrative examples, explaining a useful and advantageous embodiment. The invention is defined by the claims and is not intended to be limited to the specific embodiments used to explain the invention. In particular, the specific example embodiments also illustrate many advantageous embodiments of the invention, which are advantageous in carrying out the invention but are not absolutely necessary.

[0051] Figure 1 A portion of a production and / or conveying device 1 of an industrial production and / or conveying line is shown, on which a workpiece 2 is conveyed in a conveying plane 3 along a conveying direction 4 at a known, particularly uniform, conveying speed. The conveying device 1 has a stationary frame 5 and a conveying element 6 that moves relative to the frame 5. The workpiece 2 is placed on the conveying element 6 and thus conveyed in the conveying direction 4.

[0052] The inspection device 10 includes an optical inspection device 11, which is fixed to the mounting plate 7 of the frame 5 of the production and / or transfer device 1 by a positioning device 12. The positioning device 12 is designed as a SCARA robot with three axes of motion 13, 14, and 15, which can easily perform movement of the optical inspection device 11 parallel to the transfer plane 3 (or parallel to the surface of the workpiece 2 which is usually parallel and aligned with the transfer plane 3).

[0053] For this purpose, the SCARA robot 12 (used herein and hereinafter synonymous with the term positioning device) includes a first motion axis 13, a second motion axis 14, and a third motion axis 15, all three of which are orthogonal to the transfer plane 3. The first motion axis 13 is guided in a mounting base 16, which is fixed to a mounting plate 7 on the frame 5 of the production and transfer device 1, and allows the first arm 17 of the positioning device 12 to rotate about the first motion axis 13 (rotation axis). The arm 17 is actually formed by an upper arm and a lower arm; for clarity, only the upper arm is shown. The second motion axis 14 is guided at the end of the first arm 17 opposite to the first motion axis 13, and allows the second arm 18 of the positioning device 12 to rotate about the second motion axis 14 (rotation axis). The third motion axis 15 (on which the optical inspection device 11 is fixed) is guided at the end of the second arm 18 opposite to the second motion axis 14. The third motion axis 15 allows the optical inspection device 11 to rotate about the third motion axis 15 (rotation axis).

[0054] During the aforementioned rotation, the distance between the optical inspection device 11 and the workpiece 2 (or the material surface of the workpiece 2) remains unchanged. Through corresponding coordinated rotational movements about the first, second, and third rotation axes 13, 14, and 15, the optical inspection device 11 can be moved to a previously identified potential defect location 30 on the workpiece 2, and the optical inspection device 11 moves synchronously with the workpiece 2 while the workpiece 2 moves at a known (preferably uniform) conveying speed in the conveying direction 4. For this purpose, corresponding movement patterns of the three motion axes 13, 14, and 15 can also be predefined in a control unit (not shown), thereby enabling particularly easy and rapid movement of the optical inspection device 11. Even unrelated to this, the control unit is preferably adapted to achieve synchronous movement of the optical inspection device 11 and the workpiece 2 on the production and conveying device 1. For this purpose, the control unit is aware of the conveying direction 4 and the (each current) conveying speed of the production and / or conveying device 1, for example, through an interface with the production and / or conveying device 1 or a sensor system connected to the control unit and appropriately selectable by those skilled in the art.

[0055] According to a particularly preferred embodiment, the optical inspection device 11 can be oriented such that the imaging unit 21 of the optical inspection device 11 captures the same image area 31 around the potential defect location 30 on the workpiece 2 during movement. This makes it possible to take multiple images of the potential defect location 30 under different imaging conditions (e.g., bright field and dark field illumination) and / or at different intervals, thereby enabling better detection and classification of defects, even when the workpiece 2 is moving.

[0056] The third motion axis 15 also allows for translational movement in the axial direction, which enables the alteration or adjustment of the distance between the workpiece 2 or its material surface and the optical inspection device 11. This can be used, for example, to focus the optical imaging unit 21 onto the surface of the workpiece 2 for fine-tuning the distance between the workpiece 2 and the optical inspection device 11, or to capture a series of images with different distances as already described. As previously mentioned, the distance can be detected using an optical distance sensor, such as a confocal dispersion sensor integrated into the optical inspection device 11. It is controlled by the aforementioned control unit, which is not shown in the accompanying drawings.

[0057] Preferably, the movement of workpiece 2 is uniform. Uniform transport of workpiece 2 reduces the risk of scratches and / or contamination deposition. Scratches are typically caused by accelerating forces acting on the workpiece relative to the transport element, such as those forces that occur during start-up and stop during transport. Contamination caused by the deposition of fine particles on the material surface typically occurs when workpiece 2 is stationary. Uniform movement of the workpiece can eliminate these causes of defects. During uniform movement, the imaging quality of the optical inspection device 11 is also better, as no significant accelerating forces act on the optical inspection device 11 during this period. According to the invention, the occurrence of accelerating forces can also be counteracted by selecting a suitable motion mode during inspection, for example, through a control unit.

[0058] Typical material testing methods that can be adapted to the above-mentioned inspection device 10 (including its control unit for controlling the optical inspection device 11 and the positioning device 12) are as follows:

[0059] Potential defect locations 30 in workpiece 2 are identified in advance or prior to the identification process. In one possible embodiment, these can be communicated to a control unit via an interface. In another alternative embodiment of the invention, these potential defect locations in the workpiece can also be determined during a process step prior to actual material testing. For this purpose, a calibrated pre-test imaging device can be provided, arranged on the production and / or conveyor line of workpiece 2, to record the material surface of workpiece 2 during transport and to identify the potential defect locations 30 by image evaluation (e.g., by altering the image structure of image regions adjacent to the potential defect location 30 or other measures known to those skilled in the art). The quality of the imaging is often insufficient for final defect detection and / or defect classification, which, according to the invention, is subsequently performed during material testing.

[0060] Because of the known imaging position in the production and / or conveyor line and the known conveying speed of the workpiece 2, the position of the potential defect location 30 on the workpiece 2 identified by the inspection device 10 is known.

[0061] Then, at least one of the possible optical inspection devices 11 is sequentially moved to the identified potential defect location 30, that is, the optical inspection device 11 is positioned at each previously identified potential defect location 30 of the workpiece 2 and moves together with the moving workpiece 2. In other words, the optical inspection device 11 moves synchronously with the workpiece 2.

[0062] Particularly preferred is to keep the image area 31 around the defect location 30 constant.

[0063] During the joint movement, the optical inspection device 11, controlled by the control unit, performs material testing, wherein preferably multiple images of the defect location 30 are captured under different recording conditions. (See later...) Figure 2 and Figure 3The structure of the preferred optical inspection device 11 shown will be explained in more detail.

[0064] According to the present invention, images can be evaluated in a generally known manner during material testing to perform accurate defect detection and / or defect classification. This can be done in a control unit or in a downstream evaluation unit (also not shown), to which images captured during material testing are forwarded for further evaluation. For example, images can be forwarded by the control unit.

[0065] In contrast to existing technologies, where precise material testing is only performed during the standby period of production and / or the conveyor line, and where more precise material testing is typically performed at only one or two typical defect locations 30 using the optical inspection device 11 within the usual cycle time, the material testing proposed according to the present invention can perform precise material testing on five to ten potential defect locations 30 within the same usual cycle time during the movement of the workpiece 2, without introducing additional standby time in the production and / or conveyor line for quality assurance purposes, or performing additional quality assurance measures after the production and / or conveyor line.

[0066] Figure 2 A preferred embodiment of the optical inspection apparatus 11 according to the invention is shown, having a partially opened housing 20 to provide a view of the imaging unit 21. A portion of the illumination unit 22 can be seen behind the imaging unit 21. The illumination unit 22 has a light source 25 and a shielded optical path that extends parallel to and partially surrounds the microscope 23. Bright-field illumination is achieved in the portion of the optical path surrounding the microscope 23, where light reflected from the flat surface of the workpiece 2 is reflected into the imaging optics of the microscope 23 to produce a bright, well-illuminated image of the workpiece surface. From the optical path advancing parallel to the microscope 23, the surface of the workpiece 2 is illuminated from the side, such that light reflected from the flat surface of the workpiece 2 is not reflected into the imaging optics of the microscope 23. This represents dark-field illumination, where light is reflected only through structures on the workpiece surface into the imaging optics of the microscope 23, and thus these structures are particularly clearly visible under dark-field illumination. Furthermore, a spacing sensor 26 is disposed adjacent to the microscope 23.

[0067] The imaging unit 21 includes a microscope 23 as an imaging optics device, to which a high-resolution camera 24 is connected for capturing high-resolution images. The microscope 23 is capable of performing particularly precise and detailed examinations of potential defects. This... Figure 3 This can also be clearly seen in the middle.

[0068] Figure 3 A more detailed description is given of the rear (relative to) Figure 2 The microscope 23 and camera 24 are inside the open casing 20. Figure 3 The third motion axis 15 of the positioning device 12 is also shown, on which the optical inspection device 11 is fixed.

[0069] Figure 4 Another embodiment of the production and conveying apparatus 101 according to the present invention is shown, which is provided with an inspection device 110, on which a plurality of (exactly two in the illustrated example) optical inspection devices 11 are provided. The optical inspection devices 11 are constructed in accordance with... Figure 1 , 2 The exemplary embodiments described in 3 are the same. Reference is made to this.

[0070] Workpiece 102 is conveyed on production and conveying device 101. Production and conveying device 101 has a conveying plane 103 defined by the contact surface of conveying element 106, on which workpiece 102 is placed. Workpiece 102 is conveyed in conveying direction 104 at a known conveying speed.

[0071] On each of the opposite transverse supports 108 of the production and conveying apparatus 101 (relative to the conveying direction 104), the production and conveying apparatus 101 includes a frame 105 on which mounting plates 107 are fixed, the mounting plates carrying the optical inspection device 11.

[0072] Multiple optical inspection devices 11 are arranged sequentially in the transport direction 104. This increases the total number of potential defect locations that can be tested on the workpiece 102. Figure 4 Defects are not shown in the image.

[0073] according to Figure 4 In the particularly preferred embodiment shown, the optical inspection devices 11 are alternately arranged on the opposing transverse supports 108. This has the following advantages:

[0074] According to the invention, the lengths of the first and second arms 17, 18 of the optical inspection device 11 are just sufficient to cover at least half, but not the entire length, of the transverse support 108. As a result, the individual optical inspection devices 11 are smaller and lighter, thus allowing them to move more easily in sync with the workpiece 102. According to the invention, by alternately arranging the optical inspection devices 11 on opposing transverse supports 108, the entire width of the production and / or conveying device 101 can still be covered. This is a particular advantage of this embodiment, which can be achieved independently or in combination with other embodiments having their respective advantages.

[0075] Figure 5 The illustration schematically depicts multiple images taken at different distances between the inspection device 11 and the opaque workpiece 2 in this case, for a defect location 30 that is not in the optical axis 32 of the inspection device 11. Figure 5The optical path and the captured images are shown in two images (33 and 33'). Therefore, a defect forms on the surface of workpiece 2. Typically, only one of the captured images (33 and 33') is in focus.

[0076] The first image 33 was taken at the first distance between the inspection device 11 and the workpiece 2. Image area 31 of image 33 is shown in... Figure 5 On the right side, there is an arrow pointing from the inspection device 11 to image 33. The same applies to image 33', which was taken at a second (smaller) distance between the inspection device 11' and the workpiece 2. The second image was taken at the position of the inspection device 11', where the inspection device 11 moved relative to the workpiece 2 only in the direction of the optical axis 32 when the first image was taken. As the workpiece 2 moves, the inspection devices 11 and 11' also move according to the invention, so there is no relative movement between the inspection devices 11 and 11' and the workpiece 2.

[0077] Images 33 and 33' are the same size. Optical axis 32 is located at the center of the image (not visible in the image, but shown here for clarification). Depending on beams 34 and 34', each beam forms a different angle with the optical axis, and the defect locations 30 and 30' in images 33 and 33' are located between the image center (optical axis 32) and the image edges 33 and 33'. Because the inspection device 11' is positioned closer to the workpiece 2, the captured image area is smaller than that of the inspection device 11, and the defect location 30' is closer to the edge of image 33'. The defect location 30' in image 33' also appears larger than the defect location 30 in image 33.

[0078] Based on the known geometry, especially the known spacing between inspection units 11, 11' and the angle between beams 34, 34' and optical axis 32, it can be calculated how the orientation of inspection unit 11 relative to workpiece 2 must be changed if the spacing between inspection unit 11 and workpiece 2 is changed and the image positions of defect locations 30, 30' in images 33, 33' are to be matched.

[0079] The relative orientation change between inspection unit 11 and inspection unit 11' (with a smaller spacing in the example shown) can be calculated in a plane parallel to the surface of workpiece 2. Superimposing these movements (spacing changes and relative position changes) yields a combined movement 35, which... Figure 5 The arrow indicates the position and can be adjusted via the positioning device 12.

[0080] Figure 6The light path through a transparent workpiece 2, inside which there is a defect 30, is schematically depicted. The light beam 36 is refracted at the surface of the workpiece 2 and passes through the workpiece as an angled beam 36'. Depending on the distance between the inspection device 11 and the transparent workpiece 2, a plane 37 parallel to the surface of the workpiece 2 is clearly imaged inside the workpiece 2; in the example shown, this is the plane 37 where the defect 30 is located.

[0081] For example, in order to scan the vertical section 38 passing through the transparent workpiece 2, when the distance between the inspection unit 11 and the workpiece 2 is changed, the inspection device 11 must also be moved relative to the workpiece in a plane parallel to the surface of the workpiece 2. This results in a combined movement 39, which in Figure 6 The arrows indicate the location, and the position can be adjusted using the positioning device 12. In another exemplary application, the combined movement 39 can also follow the refracted beam 36, for example, so that all possible defect locations along the beam 36 are displayed in the same position in the image.

[0082] According to the present invention and depending on the application, those skilled in the art can also perform other combinations of movements 35, 39 of the inspection device 11. Therefore, in Figure 5 and Figure 6 The application explained herein is merely an example of the useful superposition of the co-movement of the optical inspection device 11 and the moving (transported) workpiece 2 according to the present invention with the relative movement between the inspection device 11 and the workpiece 2. Relative movement can change the distance between the workpiece 2 or its surface and the inspection device 11, and / or the relative orientation of the inspection device 11 with respect to the workpiece 2 in a plane parallel to the surface of the workpiece 2. This superposition according to the present invention is not limited to the example shown, but can be applied by those skilled in the art to other applications.

[0083] List of reference numerals in the attached diagram:

[0084] 1 Production and / or conveying equipment

[0085] 2. Workpiece

[0086] 3. Conveyor Plane

[0087] 4. Direction of transmission

[0088] 5 Framework

[0089] 6. Transmission Element

[0090] 7 Mounting Plate

[0091] 10 Inspection device

[0092] 11 Optical inspection device

[0093] 12 Positioning Device

[0094] 13 First Motion Axis

[0095] 14 Second Motion Axis

[0096] 15 Third Motion Axis

[0097] 16 mounting brackets

[0098] 17 First Arm

[0099] 18 Second Arm

[0100] 20 Housing of optical inspection device

[0101] 21 imaging units

[0102] 22 lighting units

[0103] 23. Microscopes as part of imaging optics

[0104] 24 cameras

[0105] 25 Light Sources

[0106] 26 Spacing Sensor

[0107] 30 Potential Defect Locations

[0108] 31 Image Region

[0109] 32 optical axes

[0110] 33 Images

[0111] 34 beams

[0112] 35 Combined Movements

[0113] 36 beams

[0114] 37 Parallel planes in a workpiece

[0115] 38. Vertical section passing through the workpiece

[0116] 39 Combined Movements

[0117] 101 Production and / or conveying equipment

[0118] 102 workpieces

[0119] 103 Transport Plane

[0120] 104 Teleportation Direction

[0121] 105 Frame

[0122] 106 Transmission Element

[0123] 107 Mounting Plate

[0124] 108 Horizontal Supports

[0125] 110 Inspection Device

Claims

1. A method for material testing of a workpiece (2, 102) in a production and / or conveying line, wherein, The workpiece (2, 102) is conveyed along a conveying direction (4, 104) in a conveying plane (3, 103) of a production and / or conveying device (1, 101), wherein: An optical inspection device (11) is positioned at at least one previously identified potential defect location (30) of the workpiece (2, 102); At least one image is taken by the optical inspection device (11) at the potential defect location (30) of the workpiece (2, 102); characterized in that The workpiece (2, 102) is moved during the material test, and the optical inspection device (11) is moved together with the workpiece (2, 102), the at least one image being taken by the optical inspection device (11) during the movement of the workpiece (2, 102) and the optical inspection device (11).

2. The method of claim 1, wherein, The optical inspection device (11) is positioned at at least two previously identified potential defect locations (30) of the workpiece (2, 102) in succession.

3. The method according to claims 1 and 2, characterized in that, The optical inspection device (11) uses an imaging unit (21) with a microscope (23).

4. The method of any preceding claim, wherein, At least two images are taken of each potential defect location (30) of the workpiece (2, 102).

5. The method of claim 4, wherein, During the taking of the at least two images of the potential defect location (30), the spacing between the workpiece (2, 102) or the surface of the workpiece (2, 102) and the inspection device (11) is changed, and / or the relative orientation of the inspection device (11) with respect to the workpiece (2, 102) in a plane parallel to the surface of the workpiece (2, 102) is changed.

6. The method of any preceding claim, wherein, The optical inspection device (11) is arranged on a positioning device (12) by means of which the optical inspection device (11) is moved together with the workpiece (2, 102) on the movement of the workpiece (2, 102) in the conveying direction (4, 104) of the workpiece (2, 102).

7. The method of claim 6, wherein, A SCARA robot is used as the positioning device (12), which has a serial kinematic mechanism with three rotational movement axes (13, 14, 15), wherein the movement axis (15) is capable of rotational and translational movement, preferably all movement axes (13, 14, 15) are oriented perpendicular to the conveying plane (3, 103).

8. The method of any preceding claim, wherein, An optical spacing sensor (26) is used to measure the spacing between the workpiece (2, 102) and the optical inspection device (11), the optical spacing sensor using a confocal chromatic sensor to detect the spacing from the surface of the workpiece (2, 102).

9. An inspection apparatus for material testing of a workpiece (2, 102) which is conveyed in a production and / or conveying line along a conveying direction (4, 104) in a conveying plane (3, 103) at a conveying speed by means of a production and / or conveying apparatus (1, 101), the inspection apparatus comprising: At least one optical inspection device (11) is movably fixed on the production and / or conveying device (1, 101) by means of a positioning device (12), the optical inspection device (11) comprising an imaging unit (21) and an illumination unit (22), and at least one control unit adapted to control the positioning device (12) and the optical inspection device (11), wherein the conveying direction (4, 104) and the conveying speed of the workpieces (2, 102) in the production and / or conveying line are known in the control unit, characterized in that the control unit is adapted to move the optical inspection device (11) together with the workpieces (2, 102), at least one image being taken by the optical inspection device (11) during the movement of the workpieces (2, 102) and the inspection device (11).

10. The inspection apparatus of claim 9, wherein, The imaging unit (21) comprises a microscope (23).

11. The inspection apparatus of claim 9 or 10, characterized in that The illumination unit (22) comprises bright field illumination and / or dark field illumination.

12. The inspection apparatus of any one of claims 9 to 11, wherein, A SCARA robot is used as the positioning device (12), which has a serial kinematic system with three rotational movement axes (13, 14, 15) and one translational movement axis (15), preferably all movement axes (13, 14, 15) being oriented perpendicular to the conveying plane (3, 103).

13. The inspection apparatus of claim 12, wherein, From the fixed point of the positioning device (12) on the production and / or conveying device (1, 101), the first and second movement axes (13, 14) are exclusively rotational movement axes (13, 14), and the third movement axis (15) allows rotational movement and translational movement in the axial direction, the optical inspection device (11) also being fixed on the third movement axis (15).

14. The inspection apparatus of any one of claims 9 to 13, wherein, A plurality of optical inspection devices (11) are successively fixed to the production and / or conveying device (1, 101) in the conveying direction (4, 104), each optical inspection device having a corresponding positioning device (12).

15. The inspection apparatus of claim 14, wherein, The plurality of optical inspection devices (11) are arranged on different sides of the production and / or conveying device (1, 101) relative to the conveying area of the production and / or conveying device (1, 101).

16. The inspection apparatus of any one of claims 9 to 15, wherein, In front of the at least one optical inspection device (11) in the conveying direction (4, 104), a camera unit is provided, with which an image of the workpieces in the production and / or conveying line is taken and evaluated in the control unit by means of image recognition in order to identify potential defect locations (30).

Images