Method and coordinate measuring machine for the metrological measurement of workpieces using a display as part of a light table

Abstract

Method (2) for the metrological measurement of workpieces (3) using a coordinate measuring machine (1) with an optical sensor (7) for capturing image information of at least one workpiece (3) to be measured, characterized in that the coordinate measuring machine (1) is equipped with a display (13) as part of a light table (11), wherein during the measurement and / or subsequently during the output of the measurement results the at least one workpiece (3) to be measured rests on the display (13) of the coordinate measuring machine (1) and that during the measurement the display (13) is activated to illuminate the at least one workpiece (3) to be measured and that after the measurement the display (13) is activated to display the measurement results of the at least one workpiece (3) to be measured.

Description

[0001] The invention relates to a method and a coordinate measuring machine for the metrological measurement of workpieces using a display as a component of a light table.

[0002] Light tables for various applications are known, for example, from US 5 327 195 A, US 5 347 342 A, US 2006 / 0 030 026 A1, US 2006 / 0 237 658 A1, US 2007 / 0 069 643 A1, US 2008 / 0 308 752 A1, and US 8 562 802 B1. The published patent application US 2006 / 0 030 026 A1 discloses that LED light sources can be equipped with lenses to collimate the light emitted by the light sources. In contrast, in the published patent applications US 2007 / 0 069 643 A1 and US 2006 / 0 237 658 A1, only the far field homogeneously illuminated by a grid of LED light sources is used as the field for the light tables, without any collimation, resulting in a large installation space for these light tables. In the published patent application DE 10 2013 108 457 A1, planar illumination sources such as LCD matrices, LED matrices, or OLED matrices are used, particularly for the targeted adjustment of illumination types, such as bright-field and dark-field illumination.

[0003] In optical metrology, the vertical shadow cast by an object on a sensor or camera chip is evaluated for many applications. To do this, the black-and-white transition in an image of an object or workpiece to be measured, captured by a camera chip, is correlated with the position of the workpiece's edges. By calibrating the optical metrology used against reference objects or gauges, such a connection can be established between the black-and-white transition in the image and the actual edge position of the object.

[0004] The basic prerequisite, however, is that the shadows cast, i.e., the bright and dark areas in the captured image, actually correspond to the profile of the measured object. Optical systems intended for metrological purposes, in particular, place high demands not only on the imaging system but also on the illumination system. Therefore, the illumination is ideally adapted to the imaging system to achieve the best possible results.

[0005] For metrological purposes, a telecentric imaging optic is typically used to prevent a possibly incorrectly adjusted working distance between the imaging optic and the workpiece to be measured from resulting in a measurement error. The associated illumination optic is then usually also implemented as a telecentric illumination optic. A telecentric illumination optic is an optic whose illumination light is directed, i.e., collimated, onto the workpiece to be measured. The direction of the illumination light is aligned parallel to the optical axis of the telecentric imaging optic, unless optical deflection elements are used.

[0006] However, the use of illumination optics adapted to the imaging system is not always possible. Reasons for this include the correspondingly complex illumination system's installation space and cost structure, as a second, complete optical system must be installed in a coordinate measuring machine alongside the imaging system. As a cost-effective alternative, the telecentric imaging optics and the telecentric illumination system are generally designed to be movable relative to the light table, allowing both optical systems to be moved synchronously along the workpiece for measuring it. This avoids the need for large-format and therefore expensive optics for correspondingly large light tables.

[0007] Another alternative solution is often a light table, which can be built very flat and inexpensively thanks to the use of diffuse LED light. Due to the cost and installation space, the advantage of telecentric lighting is therefore foregone. This measure reaches its technical limitations when it comes to measuring components with surfaces that are parallel to the beam path or curved, such as a horizontal cylinder. The diffuse LED light directs reflections of the diffuse transmitted light into the imaging optics and captures them on the chip, leading to measurement errors. The "shadow cast" then no longer corresponds to the actual profile of the measuring object.

[0008] Another problem with all lighting systems and light tables arises, particularly when measuring multiple workpieces. It is often difficult for the user of the coordinate measuring machine to clearly assign or link the actual workpieces on the light table with the representation of the workpieces on the monitor of the coordinate measuring machine's evaluation computer. This connection must usually be accomplished by the user themselves by mentally transferring the representation on the monitor to the correct orientation and position of the actual workpieces. This allows, for example, a workpiece identified as defective on the monitor to also be identified on the coordinate measuring machine's light table.

[0009] In addition, when measuring multiple workpieces, there is also the problem that the signal-to-noise ratio at the detector or sensor is reduced by too much light from the light table in the spaces between the workpieces.

[0010] The object of the invention is therefore to provide a simple and cost-effective method for metrological applications and a corresponding coordinate measuring machine with a light table, with the aim of reducing the local light quantity of the light table required for the measurement to a minimum, in particular when measuring several workpieces, and of marking the workpieces on the light table with information about at least one workpiece after a measurement of several workpieces has been carried out.

[0011] This object is achieved by a method for the metrological measurement of workpieces by means of a coordinate measuring machine with an optical sensor for capturing image information of at least one workpiece to be measured, wherein the coordinate measuring machine is equipped with a display as part of a light table, wherein during the measurement and / or subsequently during the output of the measurement results the at least one workpiece to be measured rests on the display of the coordinate measuring machine and wherein during the measurement the display is controlled to illuminate the at least one workpiece to be measured and wherein after the measurement the display is controlled to show the measurement results of the at least one workpiece to be measured.

[0012] In the context of this invention, a display is understood to mean a TFT, LCD or OLED display, etc., as is known for use in mobile phones and / or tablets and / or PC monitors.

[0013] According to the invention, it was recognized that the display of a cell phone and / or a tablet and / or a PC can generate a sufficient amount of light to illuminate workpieces and in particular to illuminate the outer contours of workpieces. Furthermore, it was recognized that the pixels of such a display can be controlled individually so that, for example, no light is emitted from the spaces between the workpieces when several workpieces are measured simultaneously, thereby improving the signal-to-noise ratio of the coordinate measuring machine's sensor during such measurements. Furthermore, a display offers the flexibility, particularly compared to a conventional light table, that specific workpieces and / or their geometric features can be marked or displayed on the display after the measurement.

[0014] In one embodiment of the method according to the invention, the method comprises the following steps: - capturing or specifying at least one first overview image information of the at least one workpiece; - Defining a halo for illuminating the outer contour of at least one workpiece; - Generating the halo by controlling the display; - capturing at least one second image information of the at least one workpiece; - Determining edge information relating to the at least one workpiece based on image information; and - Comparing the geometric features of at least one workpiece obtained from the edge information with the geometric features stored in a test plan.

[0015] By first obtaining overview image information of at least one workpiece or specifying it from existing data such as CAD data, this overview image information can be used to define a halo around the outer contour of the workpiece, which is sufficient for measuring the workpiece using the coordinate measuring machine. This halo can then be generated by controlling corresponding pixels of the display, and a second piece of image information about the workpiece, the actual measurement information, can be obtained. The image information can then be examined for the position of the edges of at least one workpiece using standard libraries or standard edge detection methods.Finally, the geometric features of the at least one measured workpiece obtained from the edge information can be compared with the target values ​​of the geometric features stored in a test plan, including the tolerances of the workpiece stored there. Such a method according to the invention thus allows for the target / actual comparison of workpieces and thus quality assurance of production processes.

[0016] In a further embodiment, the method according to the invention comprises the step of displaying the at least one workpiece in tolerance and / or out of tolerance using the display. This has the advantage that, particularly when measuring multiple workpieces simultaneously, the defective workpieces whose geometric features lie outside the permissible tolerances stored in the inspection plan are displayed. This eliminates the error-prone user comparison between the display of the defective parts on the monitor of the coordinate measuring machine and the actual workpieces on the light table of the coordinate measuring machine when measuring multiple workpieces.

[0017] In one embodiment, the method according to the invention comprises the step of outputting at least one geometric feature of the at least one workpiece via the display. This allows important geometric features for the user to be displayed directly on the workpiece. This eliminates the risk of confusion between the workpieces or a transmission error from the monitor of the coordinate measuring machine to the actual workpiece.

[0018] In a further embodiment of the method according to the invention, when defining a halo, a not necessarily contiguous surface section of the display to be illuminated is defined, which extends from +5 mm to -5 mm, preferably from +1 mm to -1 mm, in the direction of the normal to the outer contour around the outer contour obtained from the overview image information. This avoids unnecessary light between the workpieces when measuring multiple workpieces.

[0019] In one embodiment of the method according to the invention, when capturing the at least one second piece of image information of the workpiece during the generation of the halo, the sensor's memory is read multiple times, and the second piece of image information is obtained by merging and / or joining the individual pieces of memory information generated therefrom. Such second piece of image information generated by stitching or mosaicing significantly reduces the scattered light component within the second piece of image information, since the exposure time for individual areas of the second piece of image information is limited compared to the time required to generate the entire second piece of image information.

[0020] Alternatively, in a further embodiment, when capturing the at least one second image information of the workpiece during the generation of the halo, the memory of the sensor is read out multiple times and the edge information of the workpiece is obtained from the individual memory information generated therefrom by merging and / or joining the individual edge information obtained therefrom.

[0021] In one embodiment of the method according to the invention, geometric features of the workpiece are determined based on the obtained edge information, either automatically or upon user request. This enables quality assurance, since, for example, the geometric features of the workpiece relevant for quality assurance are automatically determined according to a test plan and made available for further evaluation. Alternatively or additionally, such a selection of geometric features can also be performed through user interaction.

[0022] The present object is further achieved by a coordinate measuring machine comprising a light table for generating a field to be illuminated and an optical sensor for the metrological measurement of at least one workpiece, wherein the field to be illuminated by the light table can be selectively changed temporally and spatially, and wherein the light table includes a display as a component. In this embodiment of the coordinate measuring machine according to the invention, the display shows at least one geometric feature and / or its deviation from a target value of the geometric feature of the at least one workpiece as a numerical value in the immediate vicinity of the support location of the workpiece on the display for viewing by the user of the coordinate measuring machine.As already mentioned above, the invention recognizes that the individual controllability of the individual pixels of a display makes it possible to use such a display for the targeted illumination of the outer contours of workpieces and / or for displaying workpieces when measuring workpieces using a coordinate measuring machine. Furthermore, the actual values ​​of the geometric features of the workpieces can be shown directly on or below the actual workpieces on the display. Thus, the user receives information about the measured geometric features directly via the display and can additionally or alternatively have the deviation of the geometric features from the desired target values ​​of the workpieces displayed.This has the direct advantage that the otherwise necessary viewing of the coordinate measuring machine monitor is no longer necessary and that the user receives feedback on the quality of the workpieces directly when manually loading and unloading the coordinate measuring machine.

[0023] In one embodiment of the coordinate measuring machine according to the invention, the display is a color display, allowing shape deviations of at least one workpiece that are outside the tolerance range to be indicated using a specific color illumination of the workpiece. This makes it possible, for example, to mark a defective workpiece in red while it is still lying on the coordinate measuring machine's light table, ensuring immediate sorting by the user of the coordinate measuring machine with a very low risk of confusion.

[0024] In one embodiment of the coordinate measuring machine according to the invention, the display is designed such that the illuminating light leaves the field to be illuminated almost vertically, with the local centroid angles of the illuminating light exhibiting deviations from the vertical with respect to the field to be illuminated of less than 5°, preferably less than 2°. This ensures telecentric or vertical illumination of workpieces.

[0025] In a further embodiment of the coordinate measuring machine according to the invention, the maximum local aperture angles of the illumination light when leaving the field to be illuminated have a deviation of less than 5°, preferably less than 2°, relative to the corresponding local centroid angle. This ensures a homogeneous or, as far as possible, parallel illumination angle distribution.

[0026] In one embodiment of the coordinate measuring machine according to the invention, the light table comprises a louvre filter for aligning the display's illumination light. This louvre filter is made of a film. Film louvre filters are a cost-effective measure for aligning illumination light and, at the same time, for homogenizing or parallelizing its angular distribution.

[0027] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention with reference to the figures, which illustrate details essential to the invention, and from the claims. The individual features can be implemented individually or in combination in a variant of the invention.

[0028] Embodiments of the invention are explained in more detail below with reference to the figures. Fig. 1 a schematic representation of a coordinate measuring machine of the prior art; Fig. 2 a schematic representation of a coordinate measuring machine according to the invention; Fig. 3 a schematic representation of a first overview image information of a workpiece to be measured; Fig. 4 a schematic representation of a halo around the workpiece to be measured; Fig. 5 a schematic representation of a second overview image information of a workpiece to be measured when using a display for illumination; Fig. 6 a schematic representation of the display of a measured workpiece in tolerance and / or out of tolerance and the display of at least one geometric feature of the measured workpiece; and Fig. 7 a schematic representation of an embodiment of the method according to the invention.

[0029] Fig. Figure 1 shows, purely by way of example, a coordinate measuring machine 1a of the prior art. This coordinate measuring machine 1a comprises a light table 11a with several light sources 13a, an imaging optics 5, and a sensor 7, usually a CCD or CMOS chip. Using the diffuse illumination light of the light table 11a, Fig. 1 a workpiece 3 is illuminated. It is based on the Fig. 1 clearly shows that not only light rays 9 exiting perpendicular to the light table 11a, but also dashed light rays exiting the light table at an angle. These light rays of the illumination light exiting at an oblique angle lead to a particularly sharp result in three-dimensional objects as workpiece 3, such as a Fig. 1, leads to the fact that the outer contour of the workpiece 3 to be measured is not clearly projected as a shadow by the imaging optics 5 onto the sensor 7 as a light-dark transition. The outer contour of the Fig. The sphere 3 shown as an example in Figure 3 is, so to speak, blurred by the illumination rays emerging at an oblique angle; when the shadow is projected onto the sensor 7, a very large-area light-dark transition occurs across many pixels of the sensor 7. Such a large-area light-dark transition is naturally associated with a large measurement error with regard to the outer contour, which is identified as an edge in the image data. Accordingly, state-of-the-art coordinate measuring machines for measuring the outer contour of three-dimensional workpieces often use so-called telecentric illumination, in which the light rays are aligned perpendicular to the field of the light table to be illuminated.However, such telecentric light tables require complex optics to align the light, usually implemented as condensers, which require a lot of installation space, especially for large-area light tables, and also cause very high costs.

[0030] The Fig. Figure 2 now shows, by way of example, a coordinate measuring machine 1 according to the invention for recording image information of a workpiece 3 by means of an imaging optics 5 and a sensor 7. In the coordinate measuring machine 1 according to the invention, the light table 11 comprises at least one display 13 for illuminating and / or displaying workpieces 3. This display 13 of the coordinate measuring machine 1 according to the invention is a typical TFT, LCD or OLED display, etc., as used in mobile phones and / or tablets and / or PCs. Furthermore, the light table 11 comprises a field 15 to be illuminated or the light table 11 has such a field 15 to be illuminated for illuminating workpieces 3 resting on the light table 11. The light 9 of the display 13 is aligned in parallel by an optional lamellar filter 17 of the light table 11 shown. As an alternative to the Fig. 2, the light table 11 of the coordinate measuring machine 1 according to the invention can also consist only of the display 13 itself, or the display 13 itself can comprise such a louvre filter for aligning the display light. As a rule, such a louvre filter, as shown in the Fig. 2, the louvre filter 17 is designed to direct the illumination light by two crossed louvre filter foils. Such foils are known from ATMs or PC or laptop monitors to restrict the viewing angle against unwanted viewers. The parallel light 9, which is aligned by the aforementioned measures, now allows the shadow cast by the Fig. 3, the sphere 3 shown as a workpiece 3 on the sensor 7 also corresponds to the actual outer contour of the sphere 3. To fully capture the entire outer contour of the sphere 3, it is only necessary to determine the outer contour as edge information from the detected light-dark transition of the image information.

[0031] The Fig. Figure 3 schematically shows a first overview image information about a workpiece 3 located on the light table 11 of the coordinate measuring machine 1 according to the invention. This overview image information of the workpiece 3 can be recorded with the ambient light of the coordinate measuring machine and / or using the light table 11. The Fig. The workpiece 3 shown in Figure 3 is chosen only as an example; it may be a sphere attached to a tapered cylinder. The part of the light table 11 covered by the workpiece 3 appears dark as a shadow in the overview image information recorded by sensor 7 when the light table 11 is used to illuminate the workpiece 3 and is therefore Fig. 3 is shown hatched. The uncovered part of the light table, however, appears bright.

[0032] The outer contour can now be obtained from the overview image information of workpiece 3, for example, by extracting the edge contours of the outer contour from the acquired overview image information using known, state-of-the-art evaluations of light-dark transitions in pixel information. This results in point clouds in a plane as a data set of the outer contour. Alternatively, the point clouds of the outer contours can be generated using software from the overview image information specified by a CAD data set or an inspection plan.

[0033] Fig. 4 now schematically shows a second image information that was recorded using the method 2 according to the invention or the coordinate measuring machine 1. This second image information represents the shadow cast by the workpiece 3 analogously to Fig. 3 again, whereby around the outer contour of the workpiece 3 or the boundary of the shadow a Fig. 4 brightly shown light halo 23 extends. However, in Fig. 4, strictly speaking, only a part of the generated halo 23 is shown, since the actually generated halo 23 extends below the workpiece 3. This ensures that the outer contour of the workpiece 3 is also completely illuminated for measurement. In this respect, a real halo 23 is generated, which is slightly larger than the halo 23 shown in the second image information of the Fig. 4, which the sensor 7 can record. The remaining area of ​​the light table 11 outside the light halo 23 is used to obtain the second image information according to the Fig. 4 is not illuminated and therefore remains dark. Thus, this part of the light table 11 is also hatched like the workpiece 3 in the representation of the second image information in Fig. 4 is shown.

[0034] As a necessary atrium with a certain minimum depth of the atrium 23 is used in connection with the Fig. 4 is understood to mean a not necessarily continuous surface section of the light table 11 to be illuminated, which extends from + 5 mm to - 5 mm, preferably from +1 mm to - 1 mm in the direction of the normal of the outer contour around the outer contour obtained from the overview image information. Fig. 5 shows alternatively to Fig. 4 schematically shows the case of a second image information which has been recorded with the method 2 according to the invention or with the coordinate measuring machine 1 during the generation of an extended halo 23 for illuminating a workpiece 3 through the light table 11. Such an extended halo 23 of the Fig. 5 can extend to the edge of the field 15 of the light table 11 to be illuminated. Extended light halos 23 are particularly necessary when new workpieces 3 are to be inspected repeatedly, for example, as part of a quality control process embedded in the manufacturing process, and it cannot be guaranteed that the workpieces 3 are always placed in the same position on the light table with high accuracy. By means of these extended light halos, it can thus be ensured that the outer contour of workpieces 3 placed on the light table 11 is sufficiently illuminated for a measuring process, even if the overview image information of the placed workpiece 3 has not been previously recorded but is specified, for example, by prefabricated test plans.

[0035] The Fig. 6 schematically shows the display of a workpiece 3 on the light table 11 by the display 13 from the user's perspective in a top view, wherein the workpiece 3 rests on the light table 11 of the coordinate measuring machine 1. In the case of another embodiment, in which the light table 11 consists only of the display 13, the workpiece 3 then rests directly on the display 13. The display of the workpiece 3 or the representation of the measurement results of a workpiece 3 can now consist of it being illuminated by a halo 19 for visualization for the user in the case of a component that is out of tolerance. Alternatively, workpieces 3 that are in tolerance can also be displayed with a corresponding halo 19. Additionally or alternatively, these halos 19 can also be kept in different colors in the case of a color display, depending on whether the workpiece 3 is considered to be within or outside of tolerance after the measurement. The display of a workpiece 3 orAs an alternative or in addition to a light halo 19, the representation of a numerical value (X) of at least one geometric feature (21) of the workpiece 3 on the light table 11 or display 13 can also serve as a representation of the measurement results of a workpiece 3. Such a representation of a numerical value (X) on the display can also be provided with an indication of the unit of measurement associated with the numerical value.

[0036] The Fig. 7 schematically shows an embodiment of the method 2 according to the invention for the metrological measurement of workpieces 3 by means of a coordinate measuring machine 1, wherein the coordinate measuring machine 1 comprises a light table 11 for illuminating workpieces 3 and an optical sensor 7 for capturing image information of the workpiece 3 and wherein the method 2 comprises the following steps: - Acquisition 4 or specification 4 of at least a first overview image information of the workpiece 3; - Definition 6 of a halo 23 for illuminating the outer contour of the workpiece 3 based on the outer contour of the workpiece 3 obtained from the overview image information; - generating 8 the halo 23 by the display 13 of the light table 11; - capturing 10 at least one second image information of the workpiece 3 during the generation 8 of the halo 23; and - Determining 12 edge information regarding the workpiece 3 based on the at least one second image information.

[0037] In step 4 of procedure 2 of the Fig. 7, the overview image information of the workpiece 3 can be Fig. 3 can be obtained by capturing a first image of the workpiece 3 using the sensor 7 of the coordinate measuring machine or by specifying such overview image information of the workpiece 3, for example from an inspection plan of the workpiece 3. The only important thing here is that the overview image information is available in such a way and in such a format that every point of the outer contour of the workpiece 3 plus its position and location on the field to be illuminated can be detected or specified with an accuracy of better than 10 mm or 5 mm deviation from the actual position on the field 15 to be illuminated of the light table 11. When capturing the overview image information of the workpiece 3, it is also not absolutely necessary for the light table 11 to function as a light table or for its light sources to be switched on.Acquisition of the overview image information of the workpiece 3 by means of the sensor 7, from which the outer contour can be obtained with the sufficient accuracy described above, can also be achieved by illuminating the workpiece 3 with ambient light, so that active operation of the light table 11 can be dispensed with.

[0038] Based on the outer contour of the workpiece 3 on the field 15 of the light table 11 to be illuminated, obtained from the overview image information, in step 6 of the method 2 the Fig. 7 a halo 23 is defined. In this case, either in the definition 6 of a halo 23 a not necessarily contiguous surface section of the light table 11 to be illuminated is defined, which extends from + 5 mm to - 5 mm, preferably from +1 mm to - 1 mm in the direction of the normal of the outer contour around the outer contour obtained from the overview image information. This type of definition of a halo 23 is useful for reducing stray light, provided it is sufficiently ensured that the deviation of the points of the assumed outer contour on the field of the light table 11 to be illuminated from the actual position is less than 5 mm or 1 mm. This will generally be the case if the overview image information was acquired in step 4 based on a previously taken image of the workpiece 3 on the light table 11 using the sensor 7.

[0039] When generating 8 the halo 23 according to step 8 of method 2 of Fig. 7, the display 13 is controlled accordingly. For this purpose, the data about the stored workpieces 3 to be measured can be used, provided this data was obtained, for example, from the first overview image information. This ensures that sufficient illumination is achieved for measuring the outer contour for generating a second image information.

[0040] During the generation 8 of the halo 23 according to step 8 of the method 2 of Fig. 7, according to step 10 of the method according to the invention, at least one second piece of image information of the workpiece 3 is acquired. This can be achieved either by selecting the exposure time of the sensor 7 during the acquisition 10 of the at least one second piece of image information of the workpiece 3 during the generation 8 of the halo 23 such that the second piece of image information is obtained by a single readout of the memory of the sensor 7. This makes it possible to obtain a second piece of image information of the workpiece immediately after the measurement process has ended, without having to join or combine multiple pieces of image information of the workpiece by means of stitching or mosaicing. Any additional measurement error that might be caused by this is thus avoided.

[0041] Alternatively, during the capture 10 of the at least one second piece of image information of the workpiece 3 during the generation 8 of the halo 23, the memory of the sensor 7 can be read multiple times, and the second image information can be obtained by combining and / or joining the individual pieces of memory information generated therefrom. Such second image information generated by stitching or mosaicing significantly reduces the scattered light component within the second image information, since the exposure time for individual areas of the second image information is limited compared to the time required to generate the entire second image information.

[0042] In addition, during the acquisition 10 of the at least one second image information during the generation 8 of the halo 23 of the method 2 of the Fig. 7, more than one second piece of image information of the workpiece 3 can also be captured by the sensor 7 using the described image generation methods. This is particularly appropriate when separate second pieces of image information need to be generated for different areas of the outer contour.

[0043] In the further step 12 of procedure 2 of the Fig. 7, edge information regarding the workpiece 3 is determined 12 based on the at least one second piece of image information. The determination 12 of the edge information of the workpiece 3 can be performed using common methods for determining edge transitions in pixel information. This edge information is then available for further geometric evaluations.

[0044] For example, in one embodiment of method 2 of the Fig. 7, geometric features of the workpiece are determined automatically based on the edge information obtained or upon user request. This enables quality assurance of the production process of workpiece 3, since, for example, the geometric features of the workpiece relevant for quality assurance are automatically determined according to a test plan and made available for further evaluation. Alternatively or additionally, such a selection of geometric features can also be performed through user interaction.

[0045] In the further step 14 of procedure 2 of the Fig. 7, the geometric features of at least one workpiece 3 obtained from the edge information are compared with the geometric features stored in an inspection plan. This allows it to be determined whether a workpiece was manufactured within or outside of tolerance.

[0046] According to step 16 of procedure 2 of the Fig. 7, these deviations of the at least one workpiece 3 within tolerance and / or out of tolerance, determined by comparison in step 14, can then be displayed using the display 13. For example, only the workpieces 3 out of tolerance can be provided with a halo 19. Alternatively, it is of course equally possible for only the workpieces 3 in tolerance to be provided with such a halo 19. When using a color display, the halos 19 can be designed in different colors for displaying workpieces in tolerance and workpieces out of tolerance.

[0047] Alternatively or in addition to step 16 of method 2 of the Fig. 7 can be used in step 18 of method 2 of the Fig. 7, the determined geometric features of the workpieces 3, or at least one geometric feature of at least one workpiece 3, are also output via the display 13. This allows the user to see the numerical value of at least one geometric feature of the workpiece 3 directly below the actual workpiece 3, in close proximity to the geometric conditions. This can be done optionally with or without the associated unit of measurement for the numerical value.

[0048] The Fig. The embodiment of the method 2 according to the invention shown in Figure 7, like all other methods 2 according to the invention for the metrological measurement of workpieces 3 by means of a coordinate measuring machine 1 with an optical sensor 7 for capturing image information of at least one workpiece 3 to be measured, is based on the fact that the coordinate measuring machine 1 is equipped with a display 13 as part of a light table 11, wherein during the measurement and / or subsequently during the output of the measurement results the at least one workpiece 3 to be measured rests on the display 13 of the coordinate measuring machine 1 and that during the measurement the display 13 is controlled to illuminate the at least one workpiece 3 to be measured and / or that after the measurement the display 13 is controlled to show the measurement results of the at least one workpiece 3 to be measured. It is therefore understood that the Fig. 7 is only a specific embodiment of the method 2 according to the invention and that the method 2 according to the invention is therefore not limited to this specifically explained embodiment of the Fig. 7 is restricted.

Claims

[1] Method (2) for the metrological measurement of workpieces (3) by means of a coordinate measuring machine (1) with an optical sensor (7) for detecting image information of at least one workpiece (3) to be measured, characterized by that the coordinate measuring machine (1) is equipped with a display (13) as a component of a light table (11), wherein during the measurement and / or subsequently during the output of the measurement results the at least one workpiece (3) to be measured rests on the display (13) of the coordinate measuring machine (1) and that during the measurement the display (13) is controlled to illuminate the at least one workpiece (3) to be measured and that after the measurement the display (13) is controlled to show the measurement results of the at least one workpiece (3) to be measured. [2] Method (2) according to claim 1, wherein the method comprises the following steps: - detecting (4) or specifying (4) at least one first overview image information of the at least one workpiece (3); - defining (6) a halo (23) for illuminating the outer contour of the at least one workpiece (3); - generating (8) the halo (23) by controlling the display (13); - capturing (10) at least one second image information of the at least one workpiece (3); - determining (12) edge information relating to the at least one workpiece (3) based on image information; and - comparing (14) the geometric features of the at least one workpiece (3) obtained from the edge information with the geometric features stored in a test plan. [3] Method (2) according to claim 1 or 2, wherein the method comprises the step: - Displaying (16) the at least one workpiece (3) in tolerance and / or out of tolerance by means of the display (13). [4] Method (2) according to one of the preceding claims, wherein the method comprises the step: - Outputting (18) at least one geometric feature of the at least one workpiece (3) by means of the display (13). [5] Method (2) according to claim 2, wherein in the definition (6) of a halo (23) a not necessarily contiguous surface section of the display (13) to be illuminated is defined, which extends from +5 mm to -5 mm, preferably from +1 mm to -1 mm, in the direction of the normal of the outer contour around the outer contour obtained from the overview image information. [6] Method (2) according to claim 2, wherein during the acquisition (10) of the at least one second image information of the workpiece (3) during the generation (8) of the halo (23), the memory of the sensor (7) is read out several times and the second image information is obtained by merging and / or joining the individual memory information generated therefrom. [7] Method (2) according to claim 2, wherein during the acquisition (10) of the at least one second image information of the workpiece (3) during the generation (8) of the halo (23), the memory of the sensor (7) is read out several times and the edge information of the workpiece (3) is obtained from the individual memory information generated therefrom by merging and / or joining the individual edge information obtained therefrom. [8] Method (2) according to claim 2, wherein geometric features of the workpiece (3) are determined automatically or upon request of the user on the basis of the edge information obtained. [9] Coordinate measuring device (1), comprising a light table (11) for generating a field (15) to be illuminated and an optical sensor (7) for the metrological measurement of at least one workpiece (3), wherein the field (15) to be illuminated of the light table (11) is selectably variable in time and space, characterized bythat the light table (11) comprises a display (13) as a component, wherein the display (13) shows at least one geometric feature of the at least one workpiece (3) as a numerical value in the immediate vicinity of the support location of the workpiece (3) on the display (13) for viewing by the user of the coordinate measuring machine (1). [10] Coordinate measuring machine (1) according to claim 9, wherein the display (13) is a color display (13) and shape deviations of the at least one workpiece (3) out of tolerance are displayed with a specific color illumination of the workpiece (3). [11] Coordinate measuring device (1) according to one of claims 9 to 10, wherein the display (13) is designed such that the illuminating light (9) leaves the field (15) to be illuminated almost vertically, wherein the local centroid angles of the illuminating light have deviations from the vertical with respect to the field (15) to be illuminated of less than 5°, preferably less than 2°. [12] Coordinate measuring device (1) according to claim 11, wherein the maximum local opening angles of the illuminating light (9) when leaving the field (15) to be illuminated have a deviation with respect to the associated local centroid angle of less than 5°, preferably less than 2°. [13] Coordinate measuring device (1) according to one of claims 9 to 12, wherein the light table (11) comprises a lamellar filter for aligning the illumination light of the display (13) and this lamellar filter is designed as a film.

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