METHOD FOR DETERMINING, IN PARTICULAR, GEOMETRIC DEFECTS OF A LASER MACHINE FOR CUTTING, ENGRAVING, MARKING AND / OR LETTERING A WORKPIECE AND A METHOD FOR DETERMINING THE LOCATION OR POSITION OF THE CENTER POINT OF A DETECTOR ON THE DETECTOR ELEMENT AS WELL AS CALIBRATION SEGMENT AND LASER MACHINE FOR THIS PURPOSE

Description

[0001] The invention relates to a method for determining, in particular static, geometric errors of a laser machine for cutting, engraving, marking and / or labeling a workpiece and a calibration segment for determining static geometric errors of laser machines according to claims 1 and 18.

[0002] Laser plotters are already known in the prior art, in which one or more laser sources are operated. For this purpose, a laser beam is sent from the laser source to a laser head or a focusing unit, whereby the laser beam is focused in the laser head or the focusing unit by means of an optical element, in particular a lens.

[0003] Flatbed laser plotters are also known from the prior art, which are equipped with a carriage, preferably belt-driven, on which a focusing unit or laser head is also adjustable. Preferably, large, flat workpieces, such as paper, sheets, textiles, etc., are processed using a laser, in particular a laser beam.

[0004] Furthermore, galvo lasers or galvo marking lasers are known in which at least one laser source is operated, and the generated laser beam is sent to a laser head or focusing unit. A mirror is arranged in the laser head or focusing unit, which deflects the laser beam towards the workpiece. The laser beam is controlled across the entire worktable by adjusting the angle of at least one mirror and, optionally, by moving the laser head, focusing unit, or processing table.

[0005] A disadvantage of the aforementioned laser machines is that there are no provisions for detecting manufacturing defects or non-idealities (so-called static geometric errors) within the valid form and position tolerances for production, meaning that each device must be painstakingly evaluated and adjusted manually.

[0006] From DE 19732668, a device and method for calibrating beam scanning devices, in particular lasers, are known, in which the calibration device comprises a calibration plate with defined markings, in particular a grid structure, a detector device for detecting the marking, and an evaluation device for comparing the detector signal with the corresponding target positions and for generating a correction signal from the comparison. The calibration plate corresponds approximately to the size of the working area or the processing table and is placed on the processing table. The detector devices, in the form of photosensors, are located laterally above the working area to detect diffusely reflected radiation from the grid structure. The laser beam is directed onto the grid structure by a scanning head via two rotatable mirrors.Another design variant involves arranging the photosensors below the calibration plate, thereby detecting the different transmissions of the laser beam at the markings. For this to work, the calibration plate must be at least partially transparent. A disadvantage of this method is that it only provides a correction value for the deviation of the laser or laser beam.

[0007] Furthermore, DE 4437284 A1 discloses a method for calibrating the control system for deflecting a laser beam in rapid prototyping systems, in which a test image is generated by irradiating a photosensitive medium, in particular thermal paper or UV-sensitive photographic paper, with a laser beam from a galvanometer scanner at predetermined positions. A video camera or pixel scanner is used to evaluate the test image. The data is then transferred to an evaluation program to determine deviations of the actual position from the target position of the laser and to provide this information to the scanner system in a correction table. A disadvantage of this method is that the required photosensitive medium is a consumable.

[0008] WO 00 / 03833 A1 discloses a method for calibrating a laser processing machine in which a test plate is inserted in place of the workpiece, and a test mark is then created by the laser beam. The position of the test mark is subsequently measured. A calibration plate is then inserted, and a camera records the calibration plate. A downstream control unit determines any image aberration caused by the camera and, taking this aberration into account, calculates an optical offset of the laser source from the measured position of the test mark. The laser beam can be adjusted across the surface of the processing table using two adjustable mirrors.

[0009] WO 2006 / 045128 A1 describes a method for engraving printing plates, in particular intaglio printing plates, using at least one laser beam source with an optically adjustable system. At a predefinable calibration position of the printing plate or a calibration plate, an actual pattern is engraved according to a predefinable target pattern using the laser beam source and the optical system. The actual pattern is then measured, and correction factors are determined from the actual pattern and the target pattern. The printing plate is then engraved taking these correction factors into account.

[0010] Furthermore, EP 3641967 B1 discloses a method and arrangement for calibrating a head system of an energy beam source, in which a calibration plate having several reference marks is arranged. A bombardment medium made of at least one material sensitive to the radiation of the source is used. An optical measuring device is moved above the bombardment medium to capture at least one image for each reference mark of the calibration plate of an area in which, on the one hand, the reference mark and, on the other hand, the target position are in close proximity.

[0011] A method with the features of the preamble of claim 1 is known from DE 101 50 129 C1, while a calibration segment according to the preamble of claim 18 is known from CN 106 735 963 A.

[0012] A disadvantage of the aforementioned documents is that all calibration systems require an additional recording device, in particular a camera or photosensor, for the inserted calibration plate.

[0013] The object of the invention is to create a method for determining, in particular static, geometric errors of a laser machine for cutting, engraving, marking and / or labeling and a calibration segment, in which, on the one hand, the aforementioned disadvantages are avoided and, on the other hand, a high level of user-friendliness is achieved.

[0014] The problem is solved by a method according to claim 1 and a calibration segment according to claim 18. Advantageous embodiments and / or method measures are described in the dependent claims.

[0015] The advantage here is that by using a calibration segment, any errors that may occur after the manufacture of a laser machine, or even in operating laser machines, particularly geometric errors, can be identified easily and quickly. This is because geometric errors result in a deviation of the laser's focal point and / or the light beam of the light source. The special design of the detector elements allows for the detection of form and position deviations, waviness, table-level misalignment, axis misalignment, etc., which can be displayed and processed on the laser machine and / or external components, especially a laptop. Furthermore, information on how to correct the errors can be accessed and displayed, so that maintenance personnel or technicians can simply work through the individual error points to hand over an optimally calibrated laser machine to the customer.Such static geometric errors occur in every laser machine due to manufacturing tolerances, so mechanical or software corrections are advantageous to increase processing accuracy. While it is not strictly necessary to correct these geometric errors, their absence is noticeable in the quality of the laser processing.

[0016] According to the invention, the detector element is formed from a 4-quadrant photodiode or image sensor and the light beam is directed onto the detector, whereupon a movement of the light beam or the detector element is carried out according to a defined path of motion, so that an intersection point with the edges of the quadrants of the detector and / or the center position of the detector is determined, whereupon the location of the center position of the detector is calculated.

[0017] The advantage here is that it provides a simple way to determine the positioned light beam on the detector element by executing a movement path. The executed movement path is recorded or measured, and a marker is placed when the beam crosses or leaves a quadrant, allowing the exact position of the light beam, or its deviation from the center point of the detector, particularly the image sensor, to be determined. When used in a calibration segment, this allows conclusions to be drawn about static geometric errors due to deviations in the positions of the detector centers in laser machines. This means that without geometric errors, the light spot or light beam would always strike the center, i.e., the center point, of the detectors or a specific, defined point on the detectors.

[0018] Advantageous measures include inserting a calibration segment, approximately the size of the worktable, into the worktable. This ensures that the calibration plate only needs to be correctly positioned on the worktable once, allowing all detector elements to be subsequently accessed and evaluated. An automated process is preferably used, as the individual positions of the detectors on the detector element are known. This allows the control unit to move to the next detector element, particularly the next detector on the next detector element, after completing the analysis of one detector. Furthermore, a large number of detector elements are arranged on the calibration plate, ensuring that all important positions are covered. The detector elements are also arranged at different heights on the calibration plate to detect all geometric errors., for example, that several detector elements are arranged directly on the calibration plate, several detector elements at a height of 10mm, several detector elements at a height of 20mm and several detector elements at a height of 30mm on a calibration plate, etc.

[0019] However, measures are also advantageous where one or more calibration segments, smaller than the size of the worktable, are inserted into the worktable. This allows even larger worktables to be easily analyzed by inserting a small, easily handled calibration plate several times to perform a complete analysis. Alternatively, it is also possible to use multiple calibration segments, each smaller than the worktable. This means that two or more calibration segments are placed on the worktable simultaneously, allowing the detector elements to be scanned and processed to identify defects.

[0020] Advantageous measures involve repeatedly inserting the calibration segment at different positions on the worktable. This allows the quality of the analysis to be influenced by the numerous different insertion positions. If the calibration segment is repositioned only a few times, the analysis quality is lower than if it is inserted at many different positions on the worktable. It is also possible to insert the calibration segment in different orientations.

[0021] Advantageous measures are those in which the light-sensitive detector elements, especially the center points of the detectors, are precisely measured relative to each other, and preferably the data is accessible on the calibration segment or stored in the control unit or an external component, particularly a laptop, or in the cloud. This allows the subsequent detector elements to be automatically controlled or moved to the next detector element after the initial positioning of a light beam on that element, thus enabling the determination of the deviations of the light beam from the center point of a detector at the different positions. It is essential that the measurement of the detector centers and their relative positions is recorded as accurately as possible.If the position of the detector elements is stored on the calibration segment, it is advantageous to connect the calibration segment directly to the laser machine and / or the external component so that the positions can be transmitted, enabling an automatic process or evaluation.

[0022] According to the invention, a photodiode, in particular a 4-quadrant photodiode, or an image sensor is used on the detector element.

[0023] This ensures that illumination with a light beam, especially with the laser pointer, onto the light-sensitive layer, i.e. the detector, is easily detected and the center position of the detector element, especially the detector, can be determined.

[0024] According to the invention, a defined path is traced with the activated light beam, preferably by adjusting the focusing unit or laser head, in order to evaluate the position of the light beam, in particular the laser pointer point, at the light-sensitive detector. This allows the intersection points with the edges of the detector, especially the quadrants, to be determined by capturing the traversed path, and thus the deviation from the center point can be calculated. When using an image sensor, the deviation from the center point or measurement point can be detected by executing a trajectory path.

[0025] Advantageous measures are those in which the movement path is executed in the form of several different circles or a spiral. This ensures that all areas of the light-sensitive layer of the detector element are reached. Advantageous measures are those in which the movement path is executed in the form of a linear grid. This also ensures that all areas of the light-sensitive layer of the detector element are reached.

[0026] According to the invention, an intersection point of the light beam with the edges of the quadrants of the detector is determined. , The position of the detector's center point is then calculated. This allows for the precise determination of the deviation of the light beam's actual position from the detector's center point. Alternatively, the center position is determined using an image sensor.

[0027] However, measures are also advantageous in which the light beam is used to center the image sensor, thereby determining the sensor's center position. This ensures that, even when using an image sensor, the center point can be determined by moving the light source or the image sensor itself. In this case, the centers of the image sensors relative to each other are also measured precisely, similar to a photodiode.

[0028] According to the invention, the calibration segment includes control electronics that are connected, either wired via a terminal block or wirelessly, to the control unit of the laser machine or an external component, in particular a computer or laptop. This ensures that all necessary components for evaluating the detector points are connected to the calibration segment, thus requiring only a wired or wireless data connection.

[0029] Advantageous are measures where an optical marker, in particular a Data Matrix code or QR code, is scanned on the calibration segment to approximate its position. This allows the calibration plate to be placed in any position on the worktable, as its position can be determined by scanning or capturing the optical marker. Furthermore, additional information can be accessed and displayed.

[0030] However, measures that evaluate static geometric errors such as axis misalignment, linearity errors, axis bending, axis rotation, offset errors, etc., during the calibration process are also advantageous. This ensures that a high-quality laser machine can be delivered to the customer, as the geometric errors can be corrected beforehand by identifying them.

[0031] Advantageous measures are those in which, after evaluating static geometric errors, these are corrected mechanically, control-technically, and / or software-wise. This significantly increases the quality of a machining process.

[0032] Measures that involve performing the calibration process on laser machines at predetermined intervals to check and, if necessary, correct static geometric errors are advantageous. This ensures that geometric errors can be detected and corrected even in existing systems.

[0033] Furthermore, the object of the invention is solved by a calibration segment for determining static geometric errors of laser machines, in which at least three light-sensitive detector elements are arranged on a calibration plate, wherein the detector elements are positioned at different heights.

[0034] The advantage of this method is that it allows for the precise evaluation of the deviation of an incident light beam from the center of the detector. Furthermore, due to the varying arrangement of the calibration plate at different heights, axial misalignments can also be detected.

[0035] An advantageous design involves arranging a photodiode, particularly a four-quadrant photodiode, or an image sensor on the detector element. This ensures simple detection of the light beam striking the detector element, especially the light-sensitive detector.

[0036] It is advantageous to use a training system in which an optical marker, in particular a QR code or Data Matrix code, is placed on the calibration plate to determine its position. This allows the position / orientation of the calibration plate to be determined by scanning or capturing an image of the marker, and also enables the retrieval or retrieval of additional data.

[0037] An advantageous design is one in which control electronics for evaluating the incident light beam on a detector element, in particular the detector, are arranged on the calibration plate. This ensures that all components for the application of the calibration segment are compactly arranged on a single calibration plate.

[0038] It is important to note that, in principle, if a laser machine is manufactured correctly, particularly if the individual components are assembled properly, the emitted light beam should strike the center of the light-sensitive detector element. If the light beam deviates from the center point, a static geometric error is highly likely, which can be corrected manually / mechanically, through control engineering, and / or software.

[0039] The invention is subsequently described in the form of exemplary embodiments, whereby it is pointed out that the invention is not limited to the illustrated and described exemplary embodiments or solutions, but can be transferred to equivalent solutions.

[0040] They show: Fig. 1 is a simplified, schematic diagram of a laser machine, in particular a laser plotter, for processing a workpiece; Fig. 2 is a simplified, schematic diagram of a laser machine, in particular a flatbed laser plotter; Fig. 3 is a simplified, schematic diagram of another laser machine, in particular a galvo marking laser, for processing a workpiece; Fig. 4 is a simplified, schematic top view of a calibration segment; Fig. 5 is a side view of the calibration segment. Figure 4, in simplified, schematic representation; Fig. 6 an application example of a calibration segment placed on a processing table of a flatbed laser plotter, in which the calibration segment is smaller than the processing table, in simplified, schematic representation; Fig. 6a a schematic representation of the processing table according to Fig. 6 with several mounting positions of the calibration segment, in a simplified, schematic representation; Fig. 7 another application example of a mounted calibration segment on a processing table of a laser plotter, in which the calibration segment is approximately the same size as the processing table, in a simplified, schematic representation; Fig. 8 a detailed view of a detector element of the calibration segment with the acting light beam on the detector of a photodiode, in a simplified, schematic representation; Fig. 9 the detailed view according to Figure 8with a movement path to be carried out in dashed lines with a spiral course, in a simplified, schematic representation; Fig. 10 the further detailed view according to Figure 8 with a further variant of the movement path to be carried out in dashed lines with a linear cross-shaped course, in simplified, schematic representation; Fig. 11 a detailed view of a detector element of the calibration segment with the acting light beam on the detector of an image sensor shown, in simplified, schematic representation.

[0041] It should be noted at the outset that in the different embodiments, identical parts are provided with the same reference numerals or component designations, and the disclosures contained in the entire description can be applied analogously to identical parts with the same reference numerals or component designations. Furthermore, the positional designations chosen in the description, such as top, bottom, side, etc., refer to the described figure and must be applied analogously to any change in position.

[0042] In the Figs. 1 to 10 Exemplary embodiments of laser machines 1, in particular a laser plotter 2a, a flatbed laser plotter 2b and a galvo marking laser 2c, are shown.

[0043] In the case of the laser plotter 2a shown, according to Fig. 1In a housing 3, at least one, preferably two, beam source(s) 4 or laser sources in the form of lasers 5, 6 are arranged. The lasers 5 and 6 preferably act alternately on a workpiece 7 to be processed. The workpiece 7 is positioned in a processing area 8 of the laser plotter 1, in particular on a processing table 9, the processing table 9 preferably being height-adjustable. A laser beam 10 emitted by a beam source 4, in particular the laser 5 or 6, is sent via deflection elements 11 to at least one movable focusing unit 12 or laser head 12, by which the laser beam 10 is deflected towards the workpiece 7 and focused for processing.The control, in particular the position control of the laser beam 10 relative to the workpiece 7, is carried out by software running in a control unit 13, wherein the workpiece 7 is processed by adjusting a carriage 14, on which the focusing unit 12 is also movably arranged, preferably via a belt drive in the XY direction. It is possible, for example, that in the "engraving" processing process the adjustment of the carriage 14 is carried out line by line, whereas in the "cutting" processing process the carriage 14 is moved according to the contour to be cut, i.e., not line by line.

[0044] For such laser machines 1, in particular laser plotters 2a, it is necessary for safety reasons that a cover 15 or door 15, which is preferably at least partially transparent, must be closed to start processing the workpiece 7, as is shown in Fig. 1The operator can then manually or automatically position the laser point or light source 16, for example in the form of a laser pointer 16, in particular a light beam 17 or laser pointer point 17, which is coupled into the beam path of the laser 5, 6 and deflected towards the processing table 8 via the focusing unit 12 or laser head 12, on the inserted workpiece 7, whereupon a job 18 for processing the workpiece 7 can be started. At the end of the job 18, the carriage 14 and the focusing unit 12 or laser head 12 are preferably moved to the starting position so that the finished workpiece 7 can be removed, whereupon a new processing process can be started by inserting a new workpiece 7 or a blank 7 to be processed.It is advantageous if the end of the processing is indicated visually or audibly, so that the user does not have to constantly monitor the laser machine, especially the laser plotter 1. For the sake of completeness, it should be mentioned that adjusting the focusing unit 12 or laser head 12 with the light beam 17 activated is also possible with the cover 17 open, but the laser 5, 6 cannot be activated in this case.

[0045] According to Figures 2A similarly functioning flatbed laser plotter 2b for processing workpieces 7 is shown, wherein the flatbed laser plotter 2b is also designed to perform a job 18 for cutting, engraving, marking, and / or labeling the preferably flat workpiece 7. The flatbed laser plotter 2b has a housing 19 in which all elements, such as drives, electronics, laser source, etc., are integrated, so that the flatbed laser plotter 2b can also be operated as a stand-alone device. The flatbed laser plotter 2b has at least one processing area 20 for positioning the workpiece 7 on a processing table 21. Furthermore, the flatbed laser plotter 2b has at least one radiation source 22 in the form of a laser 23 and a control unit 24 for controlling the carriage 25, which is preferably operated by a belt drive, with a focusing unit 26 or laser head 26 arranged movably on it.The flatbed laser plotter 2b also has a light source 16, preferably in the form of a laser pointer 16, wherein the light source 16 is now designed as an additional element that is mounted or attached to the focusing unit 26 or laser head 26. When the light source 16 is activated, the light beam 17 is directed directly onto the object below, for example, the processing table 21 or the workpiece 7. For the sake of completeness, it should be mentioned that the light source 16, as in . Fig. 1 As described, it can also be integrated and coupled into the laser beam path. Likewise, it is possible that the light source 16 can be arranged additionally in the laser plotter 2a, as described in Fig. 2b.

[0046] Also included are so-called Galvo lasers 2c or Galvo marking lasers 2c, as in Fig. 3The laser beam 10 of a laser 27 is known, in which the laser beam 10 of a laser 27 is deflected and positioned towards the workpiece 7 above the workpiece 7, which is positioned on the processing table 30, via an adjustable mirror 28 in the laser head 29 or focusing unit 29. A light beam 17 (not shown) from a light source 16, in particular a laser pointer 16, can also be coupled into the beam path of the laser 27 or arranged on the laser head 12. A control unit 31 is provided for controlling and regulating the individual elements.

[0047] For the sake of completeness, it should be noted that the laser plotter 2a, the flatbed laser plotter 2b, and the galvo marking laser 2c are equipped, or may be equipped, with connections or cables for power supply or for connection to the intranet and / or internet 32. It is possible that a connection can be established via cable 33 or wirelessly via WLAN or Bluetooth with external components 34, such as a laptop 34a or computer, an automatic feeding unit, a conveyor belt, a removal robot, etc., so that data can be transferred from the external component 34, in particular the laptop 34a. For this purpose, for example, a graphic 35 and / or text 35 is created on the external component 34, in particular a computer, laptop 34a, or a control unit, using commercially available software 36, such as CorelDraw, Paint, etc., or using proprietary application software 36, in particular Ruby 36.The data is loaded and preferably exported or transferred to the control unit 13, 24, 31 of the laser machine 1 in the form of job 18. Preferably, the data to be transferred is converted by the same or different software so that the control unit 13, 24, 31 can process job 18. Of course, it is also possible for the input to be made directly at the laser plotter 2a, the flatbed laser plotter 2b, or the galvo marking laser 2c via the available input means 37, such as a touchscreen or input keys, or for a corresponding job 18 to be loaded from a storage medium, such as a cloud 38, a USB stick 39, etc. After the data, in particular the job(s) 18, have been transferred or created directly or loaded from the storage medium, the laser machine 1, in particular its control unit 13, 24, 31, processes job 18.It is possible for multiple jobs 18 to be stored simultaneously in the laser machine 1 and processed sequentially. Furthermore, it is also possible for the application software 36 to be installed in the cloud 38 and accessed from the cloud 38 via a web browser.

[0048] With such laser machines 1, it is essential that all components are assembled precisely and correctly during the manufacturing process. This necessitates a thorough inspection of the device after completion. Such inspections can reveal so-called geometric errors, such as axis misalignment, form and position deviations, encoder resolution errors, gear ratio errors, errors due to belts, pretension, etc., offset errors, and other issues. These errors can lead to deviations at the focal point of the laser 5, 6, 23, 27, particularly of the laser beam 10, and inaccuracies in positioning and orientation on the workpiece 7.

[0049] To accelerate and simplify the complex tests, the invention provides that a calibration segment 40 is placed on the processing table 9, 21, 30 and a calibration process is started. The calibration segment 40 can be smaller than the processing table 9, 21, 30, as shown in Figure 6 and 6a depicted, or approximately the same size as the worktable 9, 21, 30, as shown in Figure 7 shown, be trained. With a smaller training of the calibration segment 40, it is necessary to achieve high quality that the calibration segment 40 be several times at different positions 41 or that several calibration segments 40 be trained on the processing table 9, 21, 30, as shown. Figure 6a The calibration segment 40 is shown schematically for the processing table 30. The more often the calibration segment 40 is inserted, the more accurate the result of the calibration process. The calibration segment 40 can be inserted side by side or in any order.

[0050] From the Figures 4 and 5 The structure of the calibration segment 40 is now shown. The calibration segment 40 consists of a calibration plate 42 on which at least three, preferably four or more, as in the design in Figure 7 As shown, light-sensitive detector elements 43a,b,c,d are attached. In the illustrated embodiment, photodiodes 44a,b,c,d, in particular 4-quadrant photodiodes 44a-d, or image sensors 57, are attached to the detector elements 43(ad). Figure 11The detector element 43a-d comprises a light-sensitive detector 45a,b,c,d, which, when a photodiode 44a-d or image sensor 57 is used, is formed by the light-sensitive layer. The photodiodes 44a,b,c,d are mounted on a circuit board with electronic components (not shown) and a terminal block 46a,b,c,d. The detector element 43, in particular a photodiode 44 or an image sensor 57, comprises the light-sensitive detector 45, with which the emitted light beam 17 is detected. Here, the individual detector elements 43a-d are arranged at different heights 47 on the calibration plate 42, i.e., for example, one detector element 43d is mounted directly on the calibration plate 42, the next detector element 43c is raised by 10 mm, the next detector element 43b by 20 mm, and the detector element 43a by 30 mm, as shown in Figure 5The illustrated embodiment shows that several detector elements 43a-d arranged at the same height can be present, particularly when a plurality of detector elements 43a-d are arranged on a calibration plate 42. Furthermore, the calibration segment 40 in the illustrated embodiment includes, for example, control electronics 48 in the form of a printed circuit board 49 and electronic components (not shown) mounted thereon. Terminal strips 50a,b,c,d for connecting to the detector elements 43a-b, as shown by dashed lines, are also attached to the printed circuit board 49. A corresponding terminal strip 51 is provided so that the control electronics 48 can be connected to the laser machine 1, in particular the control unit 13, 24, 31, and / or an external component 34, in particular a laptop 34a.Of course, it is possible that the calibration segment 40 only contains the detector elements 43 and that the other elements, in particular the control electronics 48, are arranged separately. It is also possible that the terminal strips 46 and 50 can be omitted, so that the detector elements 43 are directly connected to the control electronics 48.

[0051] Furthermore, the calibration segment 40 has a preferably optical marker 52 in the form of a QR code 52a or Data Matrix code 52a. The marker 52 serves to determine the insertion position on the processing table 9, 21, 30 and other information, for which purpose a camera 53, as schematically shown in the Figure 1 and 7as is evident, or another recording device is used. After the calibration segment 40 is inserted, one or more images of the processing table 9, 21, 30 are first taken with the camera 53, as is usually necessary with a flatbed laser plotter 2b. The marker 52 is then evaluated, and the direction of the inserted calibration segment 40 can be determined based on the position of the marker 52. It is also possible that the insertion of the calibration segment 40 is measured manually or that corresponding stop positions are present.

[0052] After the insertion position has been detected manually or automatically, the calibration process for evaluating geometric errors can be continued. For this purpose, the light source 16 on the laser machine 1 is activated, or is already activated, whereupon the light beam 17 is automatically or manually positioned on a detector element 43 (ad), in particular on the detector 45 (ad), as shown schematically in Figures 8 to 10The positioning is determined by the light beam 17 striking the photodiode 44 or image sensor 57, i.e., the detector 45(ad) of the photodiode 44 or image sensor 57. This stops the focusing unit 12, 26, 29 during automatic adjustment, or indicates manual adjustment with a signal, beep, or illuminated symbol. After the light beam 17 has been positioned on the detector element 43, particularly on the detector 45, the calibration process can be executed automatically. This determines the center point position of the detector 45a-d, and then moves to the next detector element 43a-d, specifically the next detector 45 on the next detector element 43, until all arranged detector elements 43 have been accessed.

[0053] One can therefore say that a calibration segment 40 with at least three light-sensitive detector elements 43 (ad) is placed on the processing table 9,21,30 and a calibration process is started in which a light source 17 coupled into the laser beam path or an additional light source 16 mounted on the focusing unit or laser head 12,26,29, in particular a laser pointer 16, is activated and the focusing unit orThe laser head 12, 26, 29 automatically moves to a defined position or manually to a set position of a detector element 43 (ad), whereupon the impact of the light beam 17, in particular a laser pointer point 17, on the light-sensitive detector 45 (ad) is detected and evaluated, whereupon preferably the next light-sensitive detector element 43 (ad), in particular detector 45 (ad) of the detector element 43 (ad), is moved to automatically or manually until all existing light-sensitive detector elements 43 (ad) have been traversed. Subsequently, the calibration segment 40 can be repositioned if the calibration segment 40 is smaller than the processing table 9, 21, 30, as shown in . Figure 6a schematically shown, the focusing unit or laser head 12,26,29 can switch to the next calibration plate 42 when several calibration segments 40 are inserted simultaneously.

[0054] It is essential that the detector elements 43, in particular the centers or detector 45 of the detector element 43, are measured precisely relative to each other in order to enable an automatic calibration adjustment of all detector elements 43 on a calibration segment 40. The measured positions or orientations can be stored in the control electronics 48 so that they can be retrieved for evaluation by the control unit 13, 24, 31 and / or an external component 34, or the control electronics 48 can perform the evaluation and only transmit the result of the detected positions, which can then be compared with the positions approached by the laser machine 1 and used to determine the geometric errors.

[0055] In order to evaluate the position of the light beam 17 on the detector element 43, in particular the photodiode 44 or image sensor 57, the center of the photodiode 44 or image sensor 57, or of the detector 45, must be measured precisely in order to calculate any deviation. For this purpose, a 4-quadrant photodiode 44 is provided, formed from 4 quadrants 54a, 54b, 54c, and 54d, which divide the light-sensitive layer of the photodiode 44 into four areas. This means that the segmented areas of the photodiode 44 are located close together, so that there is only a narrow, cross-shaped gap between the light-sensitive quadrants 54a and 54d. If a light beam 17 now strikes the detector element 43, as described in the diagram, the center of the photodiode 44 or image sensor 57, or the detector 45, is measured precisely in order to calculate any deviation. Figures 8 and 9 and 10When a light beam is directed onto the light-sensitive layer of the photodiode 44, this triggers a current flow. Based on the ratios of the currents in the four quadrants 54a-d of the photodiode 44, the area covered by the incident light beam 17 can be determined. In the illustrated embodiment, this is quadrant 54c, on which the light beam 17 strikes.

[0056] In order to determine the exact relative position of the incident light beam 17, it is necessary that the light beam 17 be moved along a defined path of motion 55, 56, as shown in Figure 9 and 10 shown with dashed lines. Two exemplary embodiments of possible motion paths 55, 56 are shown in the Figure 9 and 10 shown, with the trajectory 55 in Figure 9 has a spiral course, whereas in Figure 10The movement path 56 is straight and cross-shaped, meaning that the focusing unit or laser head 12, 26, 19 or the processing table 9, 21, 30 are controlled accordingly to traverse a movement path 55, 56 with the activated light beam 17. Simultaneously, the detector element 43 or the control electronics 48 detect and store the intersection points when switching to another quadrant 54a, b, c, d. Subsequently, the deviation of the positioned light beam 17, in particular of the laser pointer 16, through the detected intersection points to the other quadrants 54a-d and to the center or the center of the detector 45 of the detector element 43 can be determined or calculated.

[0057] One can therefore say that a 4-quadrant photodiode 44 is arranged on the detector element 43 and the light beam 17 is directed towards one of the four quadrants 54a-d, whereupon a movement of the light beam 17 or of the detector element 43 is carried out according to a path of motion 55,56, so that an intersection point with the edges of the quadrants 54a-d of the detector 45 is determined, whereupon the location of the center position of the detector 45 is calculated, i.e., that the location or position of the center point or center position of the detector 45 is determined, in particular calculated, by the incident light beam 17 on the detector element 43.

[0058] When an image sensor 57 is used on the detector element 43, the light beam 17 is also directed onto the light-sensitive surface or layer, so that a centering movement is subsequently carried out with the light beam 17 or with the detector element 43 towards the center of the image sensor 57, whereupon the position of the center of the image sensor 57 is determined (not shown). Here too, a movement path 55, 56 is followed, whereby for the sake of completeness it should be noted that the design is not limited to the two movement paths 55, 56 shown for the application with the photodiode 44 and image sensor 57.

[0059] After all detector elements 43 of a calibration segment 40 have passed through, the calibration process stops to reposition the calibration segment 40, in particular the calibration plate 42, or to end the calibration process, so that the error analysis can then be calculated using the acquired data. A list of error parameters, as shown in the list below, can be determined and displayed. Error parameters Description Identified value P1 Skewness of the x-axis relative to the y-axis 0.00794° P2 Skewness of the x-axis relative to the y-axis is variable -0.06305° P3 Rotation of the laser beam around the E< axis -0.4565° P4 Rotation of the laser beam around the E y< -axis 1.1379° P5 Amplitude of the x-axis torsion angle -0.0221° P6 Gear ratio error of the x-axis -2.746*10 -6< P7 Gear ratio error of the y-axis -3.289*10 -5< P8 Deflection amplitude of the y-axis in the x-direction -0.890mm P9 Deflection amplitude of the y-axis in the z-direction -8,715 mm P10 Deflection amplitude of the x-axis in the y-direction -0.514mm P11 Deflection amplitude of the X-axis in the z-direction -0.536mm etc. etc. etc.

[0060] Static geometry errors can be displayed directly on the laser machine 1 or on an external component 34, in particular a laptop 34a. Error correction can then be carried out mechanically, control-related, and / or software-related. Mechanical error correction involves manually adjusting or correcting the relevant components, whereas control-related and / or software-related error correction involves storing and saving corresponding correction values. It is also possible to issue adjustment aids for individual or all error parameters to eliminate the geometry errors, such as: "turn screw x by angle y, etc." This enables simple, quick, and precise error correction of both newly assembled laser machines 1 and laser machines 1 already in operation.

[0061] As previously described, for the sake of completeness it is mentioned that the calibration segment 40 can also be inserted into the galvo marking laser 2c and the static geometric errors can be determined by activating a calibration process. It is also possible for the laser head or focusing unit 29 to be adjusted in addition to the adjustable mirror 28 in order to reach the entire processing table 30 with the laser beam 10 and / or light beam 17.

[0062] Furthermore, it is also possible for the manufacturer to calibrate existing systems at any time after delivery. This is preferably offered as a service, for example, within the framework of maintenance contracts. The system also serves as a diagnostic aid in cases of reported processing quality issues (dimensional accuracy, distortion, etc.). This can be carried out directly on-site at the customer's premises. A diagnostic and calibration process can also be performed after replacing components, such as an axis.

[0063] It is also possible that an image sensor 57 can be used on the detector element 43 instead of the photodiode 44, as is done in Figure 11This is shown schematically. Furthermore, it is also possible that the optical marker 52 serves as the designation or identifier of the inserted calibration plate 42. This is advantageous when several differently structured calibration segments 40 are present or used to identify the inserted calibration plate 42.

[0064] It should be noted that the calibration segment 40 is formed by the calibration plate 42, which includes several detector elements 43. Each detector element 43 is configured with one or more detectors 45. The detectors 45 are sensors, in particular photodiodes 44 or image sensors 57, from which a defined point, preferably the center point, is to be determined. This point, in particular the center point, has been measured precisely relative to the other points, in particular the centers of gravity.

[0065] For the sake of clarity, it should be noted that the invention is not limited to the embodiments shown, but may also include further designs and structures as defined in the claims.

Claims

1. Method for determining, in particular, static geometric errors of a laser machine (1) for cutting, engraving, marking, and / or labeling a workpiece (7), in which at least one radiation source (4,22) in the form of a laser (5,6, 23,27) is used in a housing (3,19) of the laser machine (1), wherein, when the laser (5,6, 23,27) is activated, a laser beam (10) is directed via deflection elements (11) to a focusing unit (12,26,29) or laser head (12,26,29), wherein a work table (9,21,30) is arranged for positioning a workpiece (7), wherein at least one calibration segment (40) with at least three photosensitive detector elements (43(a-d)) is placed on the work table (9,21,30), characterized in that a calibration process is started, in which a light source (16) coupled into the laser beam path or an additional light source (16) mounted on the focusing unit (12,26,29) or laser head (12,26,29), in particular a laser pointer (16), is activated, and the focusing unit (12,26,29) or the laser head (12,26,29) automatically moves to a defined position or a manually set position of a detector element (43(a-d)), whereupon the incidence of a light beam (17), in particular a laser pointer spot (17), on a photosensitive detector (45(a-d) on the detector element (43(a-d)), in particular a center point of the detector (45(a-d) on the detector element (43(a-d)), is detected and evaluated, wherein the detector (45(a-d9)) is formed from a 4-quadrant photodiode (44(a-d)) or image sensor (57) and the light beam (17) is directed onto the detector (45(a-d)), whereupon a movement of the light beam (17) or the detector element (43(a-d)) is carried out according to a defined movement path (55,56), so that in the case of a quadrant photodiode, an intersection point of the light beam (17) with the edges of the quadrants (54a-d) of the detector (45(a-d)) is determined, whereupon the position of the center of the detector (45(a-d)) is calculated, or in the case of an image sensor, the center position of the detector (45(a-d)) is determined, whereupon the next photosensitive detector element (43(a-d)), in particular the detector of the detector element (43(a-d)), is automatically or manually approached until all available photosensitive detector elements (43(a-d)) have been traversed.

2. Method according to claim 1 or 2, characterized in that a calibration segment (40) is inserted on the work table (9,21,30), which approximately corresponds to the size of the work table (9,21,30).

3. Method according to claim 1 or 2, characterized in that one or more calibration segments (40) are inserted on the work table (9,21,30), which are designed to be smaller than the size of the work table (9,21,30).

4. Method according to claim 1, 2, or 3, characterized in that the calibration segment (40) is inserted several times at different positions of the work table (9,21,30).

5. Method according to one of the preceding claims, characterized in that the photosensitive detector elements (43(a-d)), in particular the centers of the detectors (45(a-d)), have been precisely measured relative to each other and preferably the data are retrievable on the calibration segment (40) or stored in the control unit (13,24,31) or an external component (34), in particular laptop (34a) or cloud.

6. Method according to one of the preceding claims, characterized in that a plurality of detector elements (43(a-d)) are arranged on a calibration plate (42) of the calibration segment (40), wherein detector elements (43(a-d)) arranged at the same height are present.

7. Method according to one of the preceding claims, characterized in that with the activated light beam (17), a defined movement path (55, 56) is traversed by adjusting the focusing unit (12,26,29) or laser head (12,26,29) to evaluate the position of the light beam (17), in particular the laser pointer spot (17), on the photosensitive detector (45(a-d)).

8. Method according to one of claims 2 to 7, characterized in that the movement path (55) is designed in the form of several different circles or a spiral.

9. Method according to one of claims 2 to 8, characterized in that the movement path (56) is designed in the form of a linear grid.

10. Method according to one of the preceding claims 1, 3 to 8, characterized in that a centering movement onto the center of the image sensor (57) is carried out with the light beam, whereby the position of the center of the image sensor (57) is determined.

11. Method according to one of the preceding claims, characterized in that the calibration segment (40) has a control electronics (48), which is connected via a terminal strip (51) or wirelessly to the control unit (13,24,31) of the laser machine (1) or an external component (34), in particular computer or laptop (34a).

12. Method according to one of the preceding claims, characterized in that an optical marker (52), in particular a data matrix code (52a), is queried on the calibration segment for approximate determination of the position of the calibration segment (40).

13. Method according to one of the preceding claims, characterized in that the calibration process evaluates the static geometric errors such as axis misalignments, linearity errors, axis bends, axis twists, offset errors, etc.

14. Method according to one of the preceding claims, characterized in that after evaluation of the static geometric errors, these are corrected mechanically, by control technology, and / or by software.

15. Method according to one of the preceding claims, characterized in that, in particular at predetermined time intervals, the calibration process is carried out on laser machines (1) to check and, if necessary, correct the static geometric errors.

16. Calibration segment (40) for determining static geometric errors of laser machines (1), wherein at least three photosensitive detector elements (43(a-d)) are arranged on a calibration plate (42), wherein the detector elements (43(a-d)) are positioned at different heights (47) or several detector elements (43(a-d)) arranged at the same height are present, characterized in that a control electronics (48) for evaluating the incident light beam (17) on a detector element (43(a-d)), in particular detector 45(a-d)), is arranged on the calibration plate (42).

17. Calibration segment (40) according to claim 16, characterized in that a photodiode (44(a-d)), in particular a 4-quadrant photodiode (44(a-d)), or an image sensor (57) is arranged on the detector element (43(a-d)).

18. Calibration segment (40) according to claim 16 or 17, characterized in that an optical marker, in particular a QR code, for determining the position of the calibration plate (42) is arranged on the calibration plate (42).