Method for material testing of object in production and / or conveyor line, and inspection apparatus

Abstract

To provide a method for material testing of an object in a production and / or conveyor line, and an inspection apparatus.SOLUTION: The invention relates to a method for material testing of an object (2) in a production and / or conveyor line, and to an inspection apparatus (10) adapted for carrying out the material testing. During the material testing, the object (2) is transported along a conveying direction (4) in a conveying plane (3) of a production and / or conveyor device (1), an optical inspection device (11) is positioned at at least one previously identified potential defect location (30) of the object (2), and at least one image is taken by the optical inspection device (11) at the potential defect location (30) of the object (2, 102). The object (2) is moved during the material testing, and the optical inspection device (11) is moved along with the object (2), the at least one image being taken by the optical inspection device (11) during the movement of the object (2, 102) and optical inspection device (11).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for material testing of objects in a production and / or conveyor line according to the preamble of claim 1 and to an inspection device for material testing of objects transported in a production and / or conveyor line by a production and / or conveyor device at a conveying speed along a conveying direction of a conveying surface according to the preamble of claim 9. [Background technology]

[0002] In the proposed method, objects are transported along a conveying direction in a conveying plane of a production and / or conveyor device. The method can be implemented using a suitably equipped inspection apparatus having at least one optical inspection device, which will also be referred to simply as "inspection device" hereinafter. For this purpose, the optical inspection device is positioned at (meaning "in front of") at least one pre-identified potential defect location on the object. A potential defect location on the object is a recognized location on the object where a defect location to be investigated by material testing may be present. The goal and / or objective of material testing is to identify and / or classify defects so as to be able to determine whether a (relevant) defect is actually present, thereby requiring the object to be sorted and / or reprocessed as defective.

[0003] During the method, the inspection device acquires at least one image at a potential defect location of the object (image of the potential defect location). Typically, a plurality of potential defect locations are present in the object, each of which is investigated and evaluated by material testing. For this purpose, the optical inspection device may be moved sequentially to the various potential defect locations, and material testing may be carried out, in particular by acquiring one or more images of the one or more defect locations. In this specification, image is understood as an image of the defect location.

[0004] Such a method is known, for example, from US Pat. No. 6,299,499, which describes a system and method for re-inspection of flat glass defects. In automatic online inspection, the same coordinate system is used for surface inspection and re-inspection. The precise positioning of the re-inspection head is based on the coordinates provided by the surface inspection. In the re-inspection, individual defects are identified. The re-inspection head is moved to the defect location, where multiple images of individual glass layers are selectively acquired.

[0005] A drawback of the described re-inspection method is that the glass plate or object on the conveyor or production line must remain stationary during the surface inspection and subsequent re-inspection. The object does not move during the re-inspection and imaging.

[0006] Modern production systems, for example in TFT or flat glass production, have increasingly shorter unit production times. Cycle times of 10 seconds per piece are common. Traditional inspection methods, such as the one described above (stopping the object for inspection (close inspection)), reach their technical limits with such cycle times. A large portion of the workpiece's cycle time is required for transportation, which is approximately 60% to 70% of the available cycle time. The corresponding downtime available for re-inspection is 3 to 4 seconds. Within this time, one or two re-checks can be performed. If more potential defects are to be inspected, the downtime (and therefore the cycle time) must be extended to perform careful inspections. This is disadvantageous and reduces production efficiency in production plants, and is therefore usually unacceptable. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Chinese Patent No. 109632828 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the invention is therefore to propose a method for material testing in production or conveyor lines, which allows more material testing operations to be carried out within the available cycle time. [Means for solving the problem]

[0009] According to the invention, this problem is solved by a method for material testing having the features of claim 1 and an inspection device for material testing having the features of claim 9, with which the proposed method can be carried out.

[0010] In particular, it is provided that during the material test, the object is moved (uniformly according to a preferred embodiment of the present invention), the optical inspection device is moved together with the object (moved with the same uniform movement as the object according to a preferred embodiment of the present invention), and at least one image is acquired by the optical inspection device while the object and the inspection device are moving. Therefore, according to the present invention, it is proposed that the optical inspection device is moved synchronously with the object, and images are acquired during the synchronous movement of the object and the inspection device. Therefore, according to the present invention, the material test is performed while the object is moving. By utilizing not only the stop time but also the transport time during the cycle time, the number of possible check processes (inspections) can be increased for the same transport parameters and cycle time without extending the stop time, from one or two check processes, which are usually limited by the stop time, to five to ten check processes.

[0011] Thus, according to one embodiment of the proposed method, it can be provided that the optical inspection device is positioned sequentially at at least two pre-identified potential defect locations of the object, preferably at least three or four potential defect locations, particularly preferably at least five to ten potential defect locations. This means that exactly one optical inspection device of an inspection apparatus (inspection system) which possibly also includes several inspection devices is positioned at each of said potential defect locations. By utilizing the transport time during the movement according to the invention, sufficient time is ensured for this.

[0012] In one embodiment of the present invention, the optical inspection device can be an imaging unit (camera) with a microscope, which can provide high-resolution images of potential defect locations in the object, allowing for accurate detection and classification of defect locations, such as material inclusions (e.g., air inclusions or trapped particles), surface defects (e.g., asperities) or damage (e.g., scratches) during manufacturing.

[0013] According to a further preferred embodiment of the present invention, it may be provided that at least two images of each potential defect location on the object are acquired. According to the present invention, this may be done while the object and the optical inspection device are moving, such that the absolute spatial positions of the object and the optical inspection device (relative to the stationary conveyor) are different for each image, but the relative alignment between the object and the inspection device remains the same or unchanged.

[0014] In certain embodiments of the invention, during the capture of multiple images of the potential defect location, the orientation of the inspection device with respect to a plane parallel to the surface of the moving object remains unchanged (i.e., the inspection device is moved with the same movement over the transported object in accordance with the invention), and the spacing between the object or the object's surface and the inspection device preferably varies along a direction perpendicular to the object's surface. Thus, when the optical axis of the inspection device is perpendicular to the object's surface and the potential defect location is within the optical axis of the inspection device, the potential defect location on the object's surface is always at the same image position in the images of the inspection device. According to one embodiment of the proposed method, the optical axis of the inspection device may be oriented perpendicular to the object's surface at the potential defect location.

[0015] The reason for moving the inspection device along a direction perpendicular to the surface of the object is that imaging of the inspection device must be done with a very short exposure time to avoid blurring. The term "very short exposure time" is used when the movement of the object and inspection device during the exposure time can be ignored so that the acquired image is not blurred.

[0016] This requires good illumination and a large aperture of the imaging optics of the inspection device. In the latter case, the depth of field is shallow, and the distance between the object surface and the inspection device must be precisely adjusted to obtain a clear image of the object surface. Maintaining this distance precision is difficult when objects are transported on a conveyor line and the inspection device moves with them. For this reason, according to the present invention, a series of multiple images of potential defect locations on the object surface can be acquired, with the distance between the object surface and the inspection device being gradually changed between successive images. The amount of distance change (the "step height in the step change") can be particularly preferably selected to exactly correspond to the depth of field range of the imaging optics. When the distance between the object surface and the inspection device is set approximately to a clear image, acquiring an image series with a stepwise change in distance ensures that at least one image in the image series shows a clear image surface according to the present invention. According to a particularly preferred embodiment of this variant of the present invention, 4 to 10 images can be acquired in the multiple image series.

[0017] In the case of a transparent object, a further embodiment of the invention may provide that the range of the change in spacing during the acquisition of the multiple images corresponds to the thickness of the transparent object at least in the imaging direction, so that clear images are acquired for each depth of the transparent object along the recording direction, which makes it possible to identify and / or classify defects encapsulated in the transparent object, for example, in flat glass.

[0018] If the optical axis of the inspection device is not oriented perpendicular to the surface and / or the inspection device is not positioned so that the potential defect location is on the optical axis, an additional advantage can be achieved if multiple images of the potential defect location are acquired in a series of images at different intervals. The smaller the distance between the object and the inspection device, the smaller the surface area of ​​the object shown in the image and the image (always the same size) is slightly enlarged. Defects that are not within the optical axis (i.e., the center of the image) move toward the edge of the image (appear larger) as the distance decreases. This makes it more difficult to determine the exact location of the defect on the object. In a further embodiment according to the invention, it may be provided that the orientation of the inspection device with respect to the object is also changed in a plane parallel to the surface of the object during the acquisition of the multiple images. In particular, this may be done simultaneously and in coordination with the change in the distance between the inspection device and the object. According to a particularly preferred embodiment of this variant, the relative orientation of the inspection device and the object can be changed so that the potential defect location, e.g., the center point of the potential defect location, is always at the same image position. This is possible in a calibrated system due to simple beam shape considerations known to those skilled in the art and not requiring further explanation. In particular, a calibrated system means that the imaging characteristics of the inspection device's optics and the object-to-inspection device spacing are known, as will be explained in more detail below.

[0019] Another preferred embodiment of this variant can be used particularly for transparent objects, and by capturing multiple images at different distances between the object's surface and the inspection device in a series of images, different planes within the object can be clearly imaged. A visible beam from the inspection device that strikes the object's surface obliquely is refracted as it passes through the object according to the laws of refraction (depending on the optical density of the object). The change in the angle of this visible beam can also be calculated within the system according to the laws of refraction. This is known to those skilled in the art and does not require further explanation. According to the present invention, this embodiment proposes that the orientation of the inspection device relative to the object in a plane parallel to the object's surface is changed so that a selected image position, e.g., the position of the optical axis or the position of a potential defect, follows the beam path within the object. This achieves particularly high accuracy in locating defects, even in transparent objects.

[0020] According to a further preferred embodiment of the present invention, which may be combined with the further embodiments described, at least one image is acquired with bright-field illumination and at least one image is acquired with dark-field illumination. When the object is transported lying on a production and / or conveyor device, incident illumination is preferably provided (transparent illumination through the object is not provided). Regardless of the type of production and / or conveyor device, incident illumination is suitable for all materials (transparent and non-transparent), while transmitted illumination is only suitable for transparent materials. In this context, incident illumination is particularly preferred according to the present invention and is easier to construct than transmitted illumination. However, in the case of (at least partially) transparent or opaque materials, the present invention can also be realized in principle with transmitted illumination.

[0021] In a simple embodiment, bright field illumination is realized such that light is irradiated onto the object such that (in the case of a reflective object) at least a large portion of the irradiated light is or can be reflected back to the imaging optics of the inspection device. In a corresponding simple embodiment of dark field illumination, light is irradiated onto the object at an angle such that (in the case of a reflective object) the light is not or would not be reflected back to the imaging optics of the inspection device. In such a case, if the object has irregularities or scratches on its surface, some of the light will be reflected by the irregularities or scratches back to the imaging optics, and these irregularities or scratches will be easily visible in the image (as bright areas in a dark image).

[0022] Preferably, the optical inspection device comprises an imaging unit (preferably a camera with imaging optics, which according to a preferred embodiment may be designed as a microscope) and an illumination unit (preferably with bright field and dark field illumination), and according to a particularly preferred embodiment, the imaging unit and the illumination unit are fixed relative to each other (i.e. cannot be moved during use), which simplifies positioning of the inspection device.

[0023] A further preferred embodiment of the invention may provide that the optical inspection device is arranged on the positioning device, and that the optical inspection device is moved together with or by the positioning device in the conveying direction of the objects together with the movement of the objects. According to a preferred embodiment, the positioning device may be fixed to the production and / or conveyor device. This makes it particularly easy to track the movement of the positioning device in the conveying direction of the objects, since the conveying surface, conveying direction and conveying speed are predetermined for the production and / or conveyor device.

[0024] In this context, it may be particularly preferred to use as the positioning device a SCARA robot having (at least or exactly) three rotational movement axes and (at least or exactly) one translational movement axis in a serial kinematic system, all movement axes oriented perpendicular to the conveying surface. Such a positioning device allows particularly rapid, repeatable and accurate uniform movements, in particular in a movement plane oriented parallel to the conveying surface. This preferably means that the proposed positioning device allows the optical inspection device to move particularly uniformly together with the object being moved (i.e. transported) uniformly.

[0025] A serial motion system means that the coordinate origin of each subsequent axis of movement depends only on the previous axis of movement. This allows the control unit to preconfigure a sequence of movements relative to a given initial position in a predetermined direction, i.e., the direction of transport of the object on a production or conveyor device, and simultaneously coordinate the three rotation axes with uniform movements to move the optical inspection device together with the object so that the image cross-section at potential defect locations remains unchanged (within the required accuracy) (i.e., synchronized movement is achieved). In this way, multiple images can be acquired during movement and directly compared with each other. Other possible relative movements between the object and the inspection device have already been described and can easily be realized using the positioning device.

[0026] Preferably, according to the invention, the transport speed of the objects along the production or conveyor line is known in a control device. This can be read out via an interface of the production or conveyor device and / or measured by a suitable sensor system in a generally known manner. Production and / or conveyor devices for sensitive products are also known, which achieve particularly uniform and precise transport speeds using suitable control and / or feedback control units. Such production and / or conveyor devices can be used in accordance with the invention to implement the invention.

[0027] According to a particularly preferred embodiment, the SCARA robot can be fixed to the frame of the production and / or conveyor device (e.g., by a lateral strut) adjacent to or above the transport area by a first rotation axis, which rotates the first arm. A second rotation axis, which rotates the second arm, is provided at the end of the first arm opposite the first rotation axis. A third rotation axis, to which the optical inspection device is fixed, is provided at the end of the second arm opposite the second rotating object. This positions the optical inspection device above the object on a segment of a circle (the size of which is predetermined by the lengths of the first and second arms). The third rotation axis allows the orientation of the optical inspection device relative to the object to remain constant during the object's movement.

[0028] According to a particularly preferred embodiment of the present invention, the third of the aforementioned rotation axes also allows for axial translation (i.e., axial movement) of the optical inspection device to adjust the distance between the optical inspection device and the object. Due to the preferred arrangement of the rotation axis perpendicular to the conveying plane according to the present invention, the distance between the optical inspection device and the object does not change during the movement. In principle, translation can also be performed along other rotation axes, which is also an object of the present invention. However, adjusting the distance between the optical inspection device and the object via the third movement axis corresponds to a preferred embodiment. In this case, there is no need to additionally move the weight of the first and / or second arm with the corresponding actuator, and only one adjustment of the optical inspection device is required. This allows for a simpler and less vibration-prone adjustment.

[0029] Preferably, the optical inspection device may include a distance sensor that measures the distance between the object and the optical inspection device during movement. The distance between the object and the optical inspection device 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. In principle, any distance sensor can be used for this purpose.

[0030] However, according to a particularly preferred embodiment, the invention proposes using an optical distance sensor to measure the distance between the object and the optical inspection device, which detects the distance to the surface of the object using a confocal chromatic sensor. According to the invention, such a sensor can be integrated into the optical inspection device and requires little additional installation space. Evaluation is possible continuously even during movement, which allows for particularly fast control, whereby the distance can be kept constant throughout the entire movement within the required accuracy range.

[0031] The measurement principle of an optical confocal sensor is as follows: Chromatic confocal distance measurement uses the dispersion of white light (i.e., different colors) in a focusing lens, which converges light, preferably optically visible light in the mid-wavelength range (i.e., for example, green light), in the area of ​​the material surface. For this purpose, a white point light source is focused onto the object with a dispersion lens (focusing lens) through a small pinhole. Due to the dispersion, the blue light component is focused closer to the lens and the red light component is focused further away from the lens. The light reflected from the object is separated from the illumination beam path by the same lens with a beam splitter and fed to a color-sensitive optical sensor through a corresponding pinhole opening. This filters out the portion of the light that is precisely focused and reflected by the object surface. Spectral analysis of the reflected light allows for very precise detection of distance changes and corrections accordingly.

[0032] The invention therefore also relates to an inspection apparatus for material inspection of objects transported in a production and / or conveyor line by a production and / or conveyor device at a conveying speed along a conveying direction of a conveying surface, the inspection apparatus comprising at least one optical inspection device according to the features of claim 9. The optical inspection device is movably fixed to the production and / or conveyor device by a positioning device, the optical inspection device comprising an imaging unit and an illumination unit, and at least one control unit adapted to control the positioning device and the optical inspection device, the conveying direction and conveying speed of the objects in the production or conveyor line being known by the control unit. According to the invention, the control unit is adapted to move the optical inspection device together with the objects, and at least one image is acquired by the optical inspection device during the movement of the objects and the optical inspection device.

[0033] Preferably, the movement of the objects in the production or conveyor device and the movement of the optical inspection device are uniform, which avoids or at least reduces damage to the objects during transport and also prevents or at least reduces interference when taking images of the optical inspection device.

[0034] According to the invention, an inspection apparatus can be adapted to carry out the above-mentioned method or parts thereof, in particular to carry out the method according to one of claims 1 to 8. Where appropriate, the inspection apparatus is adapted for this purpose with the device components described and required for this purpose.

[0035] According to a preferred embodiment, the imaging unit may include a microscope, i.e., the optics of the imaging unit are designed to capture high resolution images of potential defect locations on the object.

[0036] A further preferred embodiment according to the invention provides that the illumination unit comprises bright field illumination and / or dark field illumination. Bright field illumination and dark field illumination which can be switched independently from one another according to the invention make it possible in particular to acquire different images of the same potential defect location with different illuminations, which enhances the detection and classification of different defects as already described.

[0037] According to a preferred embodiment, the positioning device may be a SCARA robot having (at least or exactly) three rotational movement axes and (at least or exactly) one translational movement axis in a serial kinematic system, all movement axes being oriented perpendicular to the conveying surface.

[0038] In such an embodiment, the first and second axes of movement originating from the attachment of the positioning device to the production and / or conveyor device may be exclusively rotational axes of movement, and the third axis of movement, to which the optical inspection device is also (directly) fixed, may allow rotational movement as well as axial translational movement (to adjust the spacing between the inspection device and the object).

[0039] As already mentioned, such a SCARA robot allows a particularly smooth and uniform movement of the inspection device along with the movement of objects in the production and / or conveyor device. Translational adjustment along the third movement axis is particularly advantageous, as it minimizes mass during height adjustment, as already mentioned.

[0040] According to a particularly preferred embodiment, a plurality of optical inspection devices can be provided, each of which is fixed to the production and / or conveyor device in turn in the conveying direction by an associated positioning device, thereby making it possible to increase the total number of potential defect locations that can be subjected to material testing in the intended conveyor section.

[0041] It may be particularly advantageous to arrange multiple optical inspection devices on different (preferably alternating) sides of the production and / or conveyor device's transport area (where the transported materials are located). This means that the optical inspection devices are arranged on or near two opposite sides of the production and / or conveyor device that delimit the transport area transverse to the transport direction, i.e., part of the optical inspection device is arranged on one side and part of the optical inspection device is arranged on the other side. This increases the total reachable inspection area when the length of the positioning device's arm does not cover the entire width of the object perpendicular to the transport direction. Furthermore, the range of movement of the optical positioning device can be optimized so that the optical inspection device examines by material testing each potential defect location located in the half of the object closest to the edge of the production and / or conveyor device to which the optical inspection device or its assigned positioning device is attached. This minimizes the amount of movement required for each optical inspection device.

[0042] According to a further optional embodiment, a camera unit can be provided in front of the at least one optical inspection device in the conveying direction, which camera unit acquires images of objects on the production and / or conveyor line, and the images are evaluated by the control unit by image recognition in order to identify potential defect locations. That is, potential defect locations on the objects are recognized. Since the conveying speed and the relative positioning of the camera unit and the optical inspection device are known, the potential defect locations can be subjected to a targeted material test by the optical inspection device. In principle, it is also possible to determine the locations of potential defect locations on the objects and move the optical inspection device relative to the object accordingly to these potential defect locations by the control unit.

[0043] According to the present invention, the present invention can be used for any transparent or non-transparent object for material testing, such as TFT glass, float glass, plate-like object or other article.

[0044] Further advantages, features and possible applications of the present invention are also apparent from the following description of embodiments and / or the drawings, in which all features described and / or shown are part of the subject matter of the present invention, independently of their combination in the claims or their subsequent references. [Brief explanation of the drawings]

[0045] [Figure 1] 1 shows a three-dimensional view of an inspection apparatus according to an embodiment of the present invention having an optical inspection device; [Figure 2] 2 shows an imaging unit of an optical inspection device of the inspection apparatus according to FIG. 1; [Figure 3] 2 shows an illumination unit of an optical inspection device of the inspection apparatus according to FIG. 1; [Figure 4] 1 shows a three-dimensional view of an inspection apparatus according to a further embodiment of the invention, having two optical inspection devices; [Figure 5] 1 shows a schematic representation of the beam path and acquired image of a defect location 30 from an exemplary use of an optical inspection device. [Figure 6] 2 illustrates a schematic diagram of a beam path at a defect location 30 according to another exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0046] The embodiments of the invention shown in the figures illustrate an inspection device according to the invention using illustrative examples that describe useful and advantageous embodiments. The invention is defined by the claims and is not limited to the specific embodiments used to describe the invention. In particular, the specific examples of embodiments also illustrate many advantageous embodiments of the invention that are advantageous, but not absolutely necessary, in implementing the invention.

[0047] 1 shows a section of a production and / or conveyor device 1 of an industrial production and / or conveyor line with objects 2, which are transported in a conveying surface 3 along a conveying direction 4 at a known, particularly uniform, conveying speed. The conveyor device 1 has a stationary frame 5 and conveyor elements 6 which move relative to the frame 5, on which the objects 2 rest and are thus transported in the conveying direction 4.

[0048] The inspection apparatus 10 comprises an optical inspection device 11, which is fixed to the mounting plate 7 of the frame 5 of the production and / or conveyor device 1 via a positioning device 12. The positioning device 12 is designed as a SCARA robot with three movement axes 13, 14, 15, which can easily perform a movement of the optical inspection device 11 parallel to the conveying plane 3 (or to the surface of the object 2, which is generally aligned parallel to the conveying plane 3).

[0049] To this end, the SCARA robot 12 (here and hereinafter referred to synonymously as the positioning device) includes a first axis of movement 13, a second axis of movement 14, and a third axis of movement 15, all three of which are oriented perpendicular to the conveying plane 3. The first axis of movement 13 is guided in a mount 16 fixed to a mounting plate 7 on the frame 5 of the production and conveyor device 1, allowing a first arm 17 of the positioning device 12 to rotate about the first axis of movement 13 (axis of rotation). The arm 17 is actually formed in two parts, an upper arm and a lower arm, of which only the upper arm is shown for clarity. The second axis of movement 14 is guided at the end of the first arm 17 opposite the first axis of movement 13, allowing a second arm 18 of the positioning device 12 to rotate about the second axis of movement 14 (axis of rotation). The third axis of movement 15, to which the optical inspection device 11 is fixed, is guided at the end of the second arm 18 opposite the second axis of movement 14. The third axis of movement 15 allows the optical inspection device 11 to rotate about the third axis of movement 15 (axis of rotation).

[0050] During the rotation, the distance between the optical inspection device 11 and the object 2 (or the material surface of the object 2) remains unchanged. By correspondingly coordinated rotational movements about the first, second and third rotation axes 13, 14, 15, respectively, it is possible to move the optical inspection device 11 to a pre-identified potential defect position 30 on the object 2 and to move the optical inspection device 11 synchronously with the movement of the object 2 while the object 2 moves in the conveying direction 4 at a known, preferably uniform, conveying speed. To this end, the corresponding movement patterns of the three movement axes 13, 14, 15 can also be predetermined in a control unit (not shown), which allows the movement of the optical inspection device 11 to be realized particularly simply and quickly. Furthermore, independently of this, the control unit is preferably adapted to perform the movement of the optical inspection device 11 synchronously with the production and the transport of the objects 2 on the conveyor device 1. For this purpose, the control unit knows the conveying direction 4 and the (respective current) conveying speed of the production and / or conveyor device 1, for example via an interface with the production and / or conveyor device 1 or a sensor system connected to the control unit and which can be suitably selected by a person skilled in the art.

[0051] 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 captures the same image section 31 around a potential defect location 30 on the object 2 while the imaging unit 21 of the optical inspection device is moving. This allows for the taking of several images of the potential defect location 30 under different imaging conditions (e.g. bright field and dark field illumination) and / or at different intervals, allowing for better detection and classification of defects even for a moving object 2.

[0052] The third movement axis 15 also allows translational movement in the axial direction, which makes it possible to change or adjust the distance between the object 2 or its material surface and the optical inspection device 11. This can be used, for example, to focus the optical imaging unit 21 on the surface of the object 2, or to fine-tune the distance between the object 2 and the optical inspection device 11, or to acquire a series of images at different distances as described above. As described above, an optical distance sensor, such as a confocal chromatic sensor, integrated in the optical inspection device 11 can be used to detect the distance. It is controlled by the above-mentioned control unit, which is not shown in the figures.

[0053] Preferably, the movement of the object 2 is uniform. Uniform transport of the object 2 reduces the risk of scratches and / or dirt accumulation. Scratches are often caused by acceleration forces acting on the object relative to the conveyor elements, such as those that occur during start and stop processes during transport. Dirt caused by the accumulation of particles on the material surface often occurs when the object 2 stops. These sources of defects are counteracted by uniform movement of the object. Imaging of the optical inspection device 11 is also of better quality during uniform movement, during which no significant acceleration forces act on the optical inspection device 11. According to the invention, the occurrence of acceleration forces can also be counteracted by an appropriately selected movement pattern during inspection, for example by the control unit.

[0054] Typical material testing methods to which the above-described inspection apparatus 10 (including a control unit for controlling the optical inspection device 11 and the positioning device 12) can be adapted are, for example, the following.

[0055] The potential defect locations 30 on the object 2 are identified in advance or in advance. In one possible embodiment, these can be communicated to the control unit via an interface. In another optional embodiment of the present invention, these potential defect locations on the object can also be determined in a process step before the actual material test. For this purpose, a calibrated pre-test imaging device can be provided, which is placed in the production and / or conveyor line of the object 2 to record the material surface of the object 2 during transport and identify the potential defect locations 30 by image evaluation (e.g., by changing the image structure in image areas adjacent to the potential defect locations 30 or by other measures known to those skilled in the art). The quality of the imaging is often not sufficient for final defect detection and / or defect classification, which, according to the present invention, is performed later in the course of the material test.

[0056] With a known imaging location on the production and / or conveyor line and a known transport speed of the object 2, the location of the identified potential defect location 30 on the object 2 is known to the inspection device 10.

[0057] The identified potential defect locations 30 are then moved in sequence by at least one of a possible number of provided optical inspection devices 11, which are positioned at each of the previously identified potential defect locations 30 on the object 2 and moved together with the moving object 2. In other words, the optical inspection device 11 is moved in synchronization with the object 2.

[0058] It is particularly preferred that the image section 31 around the error location 30 is kept constant.

[0059] While moving together, the optical inspection device 11, controlled by the control unit, performs the material test and preferably several images of the defect location 30 are acquired under different recording conditions, as will be explained in more detail below with reference to the structure of a preferred optical inspection device 11 as shown in Figures 2 and 3.

[0060] According to the invention, the images are evaluated in a generally known manner during the material test in order to perform accurate defect detection and / or defect classification. This can be performed in the control unit or in a downstream evaluation unit (also not shown) to which the images acquired during the material test are transferred for further evaluation. The images can be transferred, for example, by the control unit.

[0061] In contrast to the prior art, where accurate material testing is only performed during stoppage times of the production and / or conveyor line, and where more accurate material testing by the optical inspection device 11 can generally only be performed once for two typical defect locations 30 within a normal cycle time, the material testing proposed by the present invention allows for five accurate material tests for ten potential defect locations 30 while the object 2 is moving within the same normal cycle time, without the need to introduce additional stoppage times in the production and / or conveyor line solely for quality assurance, and without the need to perform additional quality assurance measures downstream of the production or conveyor line.

[0062] FIG. 2 shows a preferred embodiment of an optical inspection device 11 according to the present invention, with a partially open housing 20 to provide a view of the imaging unit 21. Parts of the illumination unit 22 are visible behind the imaging unit 21. The illumination unit 22 includes a light source 25 and a shielded beam path that runs parallel to and partially surrounds the microscope 23. In the portion of the beam path that surrounds the microscope 23, bright-field illumination is achieved: light reflected from the flat surface of the object 2 is reflected into the imaging optics of the microscope 23, producing a bright, well-illuminated image of the object's surface. From the beam path that runs parallel to the microscope 23, the surface of the object 2 is illuminated from this side, so that light reflected from the flat surface of the object 2 is not reflected to the imaging element of the microscope 23. This represents dark-field illumination: light is reflected only by structures on the object's surface to the imaging element of the microscope 23; therefore, the structures are clearly visible, particularly through dark-field illumination. Additionally, a distance sensor 26 is provided next to the microscope 23.

[0063] The imaging unit 21 comprises a microscope 23 as an imaging element, to which a high-resolution camera 24 is connected for forming a high-resolution image. The microscope 23 allows a particularly precise and detailed inspection of potential defects, which can also be clearly seen in Figure 3.

[0064] Figure 3 shows in more detail the microscope 23 and camera 24 in the housing 20, which is opened at the rear (with respect to Figure 2). Figure 3 also shows the third axis of movement 15 of the positioning device 12, to which the optical inspection device 11 is fixed.

[0065] 4 shows a further embodiment of a production and conveyor device 101 according to the invention, which comprises an inspection apparatus 110 provided with several (in the example shown, exactly two) optical inspection devices 11. The optical inspection devices 11 are configured equivalently to the above-described exemplary embodiment according to FIGS. 1, 2 and 3, to which reference is made.

[0066] The objects 102 are transported on a production and conveyor device 101. The production and conveyor device 101 has a conveying surface 103, which is defined by the contact surfaces of conveyor elements 106 on which the objects 102 rest. The objects 102 are transported in a conveying direction 104 at a known conveying speed.

[0067] On each of the opposing lateral supports 108 of the production and conveyor device 101 (with respect to the conveying direction 104), the production and conveyor device 101 comprises a frame 105 to which a mounting plate 107 is fixed, the mounting plate 107 supporting an optical inspection device 11.

[0068] Several optical inspection devices 11 are provided in succession in the conveying direction 104. This increases the total number of potential defect locations on the object 102 that can be subjected to material testing. Defects are not shown in FIG. 4.

[0069] According to a particularly preferred embodiment shown in figure 4, the optical inspection devices 11 are arranged alternately on lateral struts 108 arranged opposite one another. This has the following advantages:

[0070] According to the invention, the first and second arms 17, 18 of the optical inspection device 11 are just long enough to cover at least half the length of the lateral columns 108, but not the entire length. As a result, the individual optical inspection devices 11 are smaller and lighter and can therefore be easily moved in sync with the object 102. According to the invention, the entire width of the production and / or conveyor device 101 can nevertheless be covered by the alternating arrangement of the optical inspection devices 11 on the opposing lateral columns 108. This is a particular advantage of this embodiment, which can be realized independently of or in combination with the other embodiments having the advantages described for each of them.

[0071] 5 shows schematically the beam paths and images acquired when several images 33, 33' of defect locations 30 (two shown here) not lying on the optical axis 32 of the inspection device 11 are acquired at different distances of the inspection device 11 from the object 2, which in this case is not transparent. The defects are therefore formed on the surface of the object 2. Typically, only one of the several acquired images 33, 33' is in focus.

[0072] The first image 33 was acquired at a first distance between the inspection device 11 and the object 2. An image section 31 of the image 33 is shown on the right side of FIG. 5 , with an arrow pointing from the inspection device 11 towards the image 33. The same applies to the image 33′, which was acquired at a second (smaller) distance between the inspection device 11′ and the object 2. The second image was acquired at a position of the inspection device 11′ where the inspection device 11 has been moved relative to the object 2 only in the direction of the optical axis 32 towards the object 2 when forming the first image. When the object 2 moves, the inspection devices 11, 11′ are also moved according to the invention, so that there is no relative movement between the inspection devices 11, 11′ and the object 2.

[0073] The images 33, 33' are the same size. The optical axis 32 is at the center of the image (not visible in the image, but shown here for illustrative purposes). The viewing beams 34, 34', each of which includes a different angle with the optical axis, have defect locations 30, 30' in the images 33, 33' located between the center of the image (optical axis 32) and the edge of the image 33, 33'. Because the inspection device 11' is positioned closer to the object 2, the captured image section is smaller than that of the inspection device 11, and the location of the defect location 30' is closer to the edge of the image 33'. The defect location 30' in the image 33' is also shown larger than the defect location 30 in the image 33.

[0074] Based on the known shape, in particular based on the known spacing of the inspection units 11, 11' and the angle between the visible beams 34, 34' and the optical axis 32, it is possible to calculate how much the orientation of the inspection unit 11 relative to the object 2 needs to be changed if the spacing between the inspection unit 11 and the object 2 is changed and the image positions of the defect locations 30, 30' in the images 33, 33' coincide.

[0075] The relative change in orientation between inspection unit 11 and inspection unit 11' (at a smaller spacing in the example shown here) can be calculated in a plane parallel to the surface of object 2. Superimposing the movements (change in spacing and relative change in position) results in a combined movement 35, which is indicated by an arrow in Figure 5 and can be coordinated by positioning device 12.

[0076] 6 shows a schematic of a beam path through a transparent object 2, with a defect 30 located inside the object 2. A visible beam 36 is refracted at the surface of the object 2 and proceeds through the object as an angled visible beam 36'. Depending on the spacing between the inspection device 11 and the transparent object 2, a plane 37 parallel to the surface of the object 2, in the example shown here where the defect 30 is located, is sharply imaged inside the object 2.

[0077] For example, to scan a vertical cross section 38 of a transparent object 2, the inspection device 11 also needs to be moved relative to the object 2 in a plane parallel to the surface of the object 2 as the spacing between the inspection unit 11 and the object 2 is changed. This results in a combined movement 39, which is indicated by an arrow in Figure 6 and can be adjusted by the positioning device 12. In another exemplary application, the combined movement 39 can also follow the refracted visible beam 36, for example, so that all possible defect locations along the visible beam 36 are displayed at the same position in the image.

[0078] According to the invention and depending on the application, a person skilled in the art can also perform other combined movements 35, 39 of the inspection device 11. Therefore, the application described in Figures 5 and 6 is only an example of a useful superposition of the co-movement of the moving (conveyed) object 2 and the optical inspection device 11 proposed by the invention, and the relative movement between the inspection device 11 and the object 2. The relative movement may change the distance between the object 2 or the surface of the object 2 and the inspection device 11 and / or the relative orientation of the inspection device 11 with respect to the object 2 in a plane parallel to the surface of the object 2. This superposition proposed by the invention is not limited to the shown example and can also be applied to other applications by a person skilled in the art. [Explanation of symbols]

[0079] 1 Production and / or conveyor devices 2. Object 3. Transport surface 4. Transport direction 5 frames 6 Conveyor Elements 7 Mounting Plate 10 Inspection equipment 11 Optical Inspection Devices 12 Positioning Device 13 First axis of movement 14 Second moving axis 15 Third axis of movement 16 Mount 17 First Arm 18 Second Arm 20 Optical inspection device housing 21 Imaging unit 22 Lighting Unit 23 Microscope as part of imaging optical system 24 Camera 25 light source 26 Spacing Sensor 30 Potential defect locations 31 Image Section 32 Optical axis 33 images 34 Visible Beam 35 Combined Moves 36 Visible Beam 37 Parallel surfaces of the object 38 Vertical cross section of object 39 Combined Moves 101 Production and / or conveyor devices 102 Object 103 Transport surface 104 Transport direction 105 frames 106 Conveyor Elements 107 Mounting Plate 108 Horizontal Support 110 Inspection equipment

Claims

1. 1. A method for material testing of objects (2, 102) in a production and / or conveyor line, said objects (2, 102) being transported along a conveying direction (4, 104) in a conveying plane (3, 103) of a production and / or conveyor device (1, 101), an optical inspection device (11) positioned at at least one pre-identified potential defect location (30) of said object (2, 102); A method, wherein at least one image is acquired by the optical inspection device (11) at the potential defect location (30) of the object (2, 102), 10. A method according to claim 1, wherein the object (2, 102) is moved during the material test and the optical inspection device (11) is moved together with the object (2, 102), and the at least one image is acquired by the optical inspection device (11) during the movement of the object (2, 102) and the optical inspection device (11).

2. 2. The method of claim 1, wherein the optical inspection device (11) is positioned sequentially at at least two pre-identified potential defect locations (30) of the object (2, 102).

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

4. The method according to any one of claims 1 to 3, characterized in that at least two images of each potential defect location (30) of the object (2, 102) are acquired.

5. 5. The method according to claim 4, characterized in that during the acquisition of the at least two images of the potential defect location (30), the distance between the object (2, 102) or the surface of the object (2, 102) and the inspection device (11) and / or the relative orientation of the inspection device (11) with respect to the object (2, 102) in a plane parallel to the surface of the object (2, 102) is changed.

6. 6. The method according to claim 1, wherein the optical inspection device (11) is arranged on a positioning device (12), and the optical inspection device (11) is moved by the positioning device (12) together with the movement of the object (2, 102) in the conveying direction (4, 104) of the object (2, 102).

7. 7. The method according to claim 6, characterized in that a SCARA robot having three rotational movement axes (13, 14, 15) and one translational movement axis (15) in a serial kinematic system is used as the positioning device (12), preferably all movement axes (13, 14, 15) being oriented perpendicular to the conveying surface (3, 103).

8. 8. The method according to claim 1, wherein an optical distance sensor (26) is used to measure the distance between the object (2, 102) and the optical inspection device (11), the optical inspection device (11) detecting the distance from the surface of the object (2, 102) using a confocal chromatic sensor.

9. An inspection apparatus for material testing of objects (2, 102) conveyed at a conveying speed by a production and / or conveyor device (1, 101) along a conveying direction (4, 104) in a conveying plane (3, 103), the inspection apparatus having at least one optical inspection device (11) movably fixed on the production and / or conveyor device (1, 101) by a positioning device (12), the optical inspection device (11) including an imaging unit (21) and an illumination unit (22), and the inspection apparatus is connected to the positioning device (12) and a front 1. An inspection apparatus comprising at least one control unit adapted to control the optical inspection device (11) and the object (2, 102), wherein the conveying direction (4, 104) and the conveying speed of the object (2, 102) in the production or conveyor 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 object (2, 102), and at least one image is acquired by the optical inspection device (11) during the movement of the object (2, 102) and the inspection device (11).

10. 10. The inspection device according to claim 9, characterized in that the imaging unit (21) includes a microscope (23).

11. Inspection device according to claim 9 or 10, characterized in that the illumination unit (22) comprises bright field illumination and / or dark field illumination.

12. Inspection apparatus according to any one of claims 9 to 11, characterized in that the positioning device (12) is a SCARA robot with three rotational movement axes (13, 14, 15) and one translational movement axis (15) in a serial kinematic system, preferably all movement axes (13, 14, 15) being oriented perpendicular to the conveying surface (3, 103).

13. 13. Inspection device according to claim 12, characterized in that the first and second axes of movement (13, 14) starting from the fixing of the positioning device (12) on the production and / or conveyor device (1, 101) are exclusively rotational axes of movement (13, 14), and the third axis of movement (15), to which the optical inspection device (11) is also fixed, allows rotational and axial translational movements.

14. Inspection apparatus according to any one of claims 9 to 13, characterized in that a plurality of optical inspection devices (11) are fixed in turn to the production and / or conveyor device (1, 101) in the conveying direction (4, 104), each having an associated positioning device (12).

15. 15. Inspection apparatus according to claim 14, characterized in that the plurality of optical inspection devices (11) are arranged on different sides of the production and / or conveyor device (1, 101) with respect to the transport area of ​​the production and / or conveyor device (1, 101).

16. 16. An inspection device according to any one of claims 9 to 15, characterized in that a camera unit is provided in front of the at least one optical inspection device (11) in the conveying direction (4, 104), by means of which images of the objects in the production and / or conveyor line are acquired, and which images are evaluated in the control unit by image recognition in order to identify potential defect locations (30).

Images