Device for detecting the surface of a rotating body for a printing machine and method

Abstract

A device according to the invention for detecting the surface of a rotating body for a printing press, wherein the rotating body (2, 62) is a) a cylinder, b) a roller, c) a sleeve for a cylinder or for a roller or d) a sleeve for a cylinder or for a roller with at least one printing form arranged on the sleeve, with a motor (8) for rotating the rotating body (2, 62) about an axial rotation axis (5), with at least one light source (20) which illuminates at least one area (11a, 11b) of the surface (10) with optical light (21), and with at least one optical camera (30) for detecting at least the illuminated area (11a, 11b) of the surface (10), is characterized in that the device (1) comprises an optical device (40) which receives the light (21) from two partial beams (41), iefrom a first partial beam (42) and a second partial beam (43), to an image sensor (32) of the camera (30), that the first partial beam (42) hits or grazes the surface (10) tangentially at a first point (12) and then reaches the camera (30), and that the second partial beam (43) hits the surface (10) radially at a second point (13) - different from the first point (12) - and then reaches the camera (30). A corresponding method according to the invention is also disclosed. The invention advantageously makes it possible to carry out rapid and precise measuring, in particular to carry out different types of measurement simultaneously and / or using the same means. The invention is used, for example, in mounters for flexographic printing plates.

Description

invention

[0001] The invention relates to a device for detecting the surface of a rotating body for a printing press having the features of the preamble of claim 1 and to a method for detecting the surface of a rotating body for a printing press having the features of the preamble of claim 13. field of technology

[0002] The invention lies in the technical field of the graphics industry and there in particular in the field of measuring rotary bodies such as cylinders, rollers, sleeves, preferably flexographic printing sleeves, or plates, preferably flexographic printing plates. During the measurement, elevations of the rotary body are recorded, for example. The invention therefore also lies in particular in the field of flexographic printing, i.e. the operation of a flexographic printing press, i.e. a rotary printing press for printing with flexographic printing forms; and the operation of its peripheral devices, in particular a so-called mounter in which several flexographic printing forms are arranged on a cylinder or on a cylinder sleeve depending on the print job. In particular, the invention lies in the sub-field of the precise measurement of "mounted" flexographic printing forms, e.g. directly in the mounter. State of the art

[0003] It is already known to measure, for example, mounted flexographic printing plates, i.e. plates glued to a sleeve for later printing, or their surface.

[0004] DE102020111341A1 discloses a device for measuring elevations of the surface of a rotating body designed as a cylinder, roller, sleeve or plate of a printing press, e.g. a flexographic printing plate, with a first motor for rotating the rotating body about a rotation axis and with a measuring device, characterized in that the measuring device for contactless measuring comprises at least one light source and at least one area camera

[0005] US3907438A discloses a system for detecting the contour of a cylinder. A beam splitter is used to generate two partial beams, and a location on the cylinder to be detected is illuminated tangentially by each of the two partial beams from different directions.

[0006] DE10160297A1 discloses a device for optically inspecting the surface of a rotating body, in particular a cylinder in a printing press, wherein a camera and a light source are used to illuminate the surface and capture it as an image. The camera is typically aligned perpendicular to the surface, and the reflected light is used directly for evaluation. The device allows for basic detection of surface defects, but its optical design is comparatively simple. It lacks a differentiated beam guide that would enable targeted detection from different viewing angles, which limits the accuracy and versatility of the measurement. Furthermore, the device is not designed for different types of rotating bodies or complex printing forms, which limits its possible applications.The measurement is carried out sequentially and without simultaneous evaluation of different light paths, which significantly reduces both the speed and the precision of the surface detection compared to more advanced systems.

[0007] DE102004049879A1 discloses a device and method for measuring the diameter of a rod-shaped object, particularly in the tobacco processing industry. The object is illuminated with an optical beam, which is split into several partial beams before impact, which impinge on the object from different directions. The signals generated by the shadowing of the partial beams are used to determine the diameter. The partial beams are generated using mirrors or prisms and, after shadowing, are recombined into a common beam that impinges on a sensor array. This solution allows measurement from multiple directions without the object or the measuring device having to rotate.This solution is limited to rod-shaped objects and does not provide for a targeted combination of tangential and radial illumination paths, which makes the simultaneous detection of different surface properties or differentiated optical evaluation difficult. Furthermore, a targeted optical device for directing two specific partial beams with different angles of incidence onto the same surface is missing, which limits the flexibility and precision of surface detection.

[0008] Measuring systems are thus known. Nevertheless, the market is constantly demanding innovations, especially to produce even higher-quality printed products faster and more cost-effectively. Current systems cannot always fully meet this demand. Technical task

[0009] It is therefore an object of the present invention to provide an improvement over the prior art which in particular makes it possible to carry out a rapid and precise measurement, in particular to carry out different types of measurement simultaneously and / or with the same means. Inventive solution to the problem

[0010] This object is achieved according to the invention by a device according to claim 1 and a method according to claim 13.

[0011] Advantageous and therefore preferred developments of the invention emerge from the subclaims as well as from the description and the drawings.

[0012] A device according to the invention for detecting the surface of a rotating body for a printing press, wherein the rotating body is a) a cylinder, b) a roller, c) a sleeve for a cylinder or for a roller or d) a sleeve for a cylinder or for a roller with at least one printing form arranged on the sleeve, with a motor for rotating the rotating body about an axial axis of rotation, with at least one light source which illuminates at least one area of ​​the surface with optical light, and with at least one optical camera for detecting at least the illuminated area of ​​the surface, is characterized in that the device comprises an optical device which receives the light from two partial beams, iefrom a first partial beam and a second partial beam, to an image sensor of the camera, that the first partial beam hits or touches the surface tangentially at a first point and then reaches the camera, and that the second partial beam hits the surface radially at a second point - different from the first point - and then reaches the camera.

[0013] A method according to the invention for detecting the surface of a rotating body for a printing press, wherein the rotating body is a) a cylinder, b) a roller, c) a sleeve for a cylinder or for a roller or d) a sleeve for a cylinder or for a roller with at least one printing form arranged on the sleeve, and wherein a motor rotates the rotating body about an axial axis of rotation, at least one light source illuminates at least one area of ​​the surface with optical light and at least one optical camera detects at least the illuminated area of ​​the surface, is characterized in that an optical device directs the light of two partial beams, i.e. of a first partial beam and a second partial beam, to the camera in such a way that a first point on the surface is detected tangentially and a second point on the surface is detected radially at the same time. Advantageous embodiments and effects of the invention

[0014] The invention (as a device and / or as a method) advantageously enables rapid and precise measurement, in particular, performing different types of measurements simultaneously and / or using the same means. The invention is used, for example, in mounters for flexographic printing plates.

[0015] The invention advantageously makes it possible to save measuring time when measuring a (rotating) object, e.g. a flexographic printing form mounted on a sleeve, since two different, preferably optical measurements can be carried out simultaneously or close to one another in time or in parallel: a tangential measurement (of the surface relief) using the shadowing method or transmitted light method and a radial measurement (of the surface) using the top light method. The camera used does not have to be moved (except possibly in the axial direction if there are not several cameras arranged in the axial direction), which saves time. Its focus also does not have to be changed, which also saves time. The mirror(s) used also does not have to be moved (except possibly in the axial direction), which also saves time.A further advantage arises from the now possible compact design, since the same camera and / or the same optical device can be used for both measurements. Further developments of the invention

[0016] Preferred developments of the invention as a device (hereinafter referred to as "developments") are described below. These can also be combined with one another, where technically possible.

[0017] A further development can be characterized by a first optical path of length L1 from the first location to the camera and a second optical path of length L2 from the second location to the camera having the same length, i.e., L1=L2. In this way, focus adjustment or change can be prevented (only a one-time initial focus adjustment is required). In fact, L1 and L2 may differ insignificantly from each other, e.g., L2 may be insignificantly smaller than L1; however, this deviation then lies within the optical tolerance range, i.e., still within the focus of the camera, so a focus change is not necessary.

[0018] A further development can be characterized in that the optical device deflects the second partial beam, e.g., by reflecting it. A further development can be characterized in that the optical device does not deflect the first partial beam, e.g., does not reflect it, but rather lets it pass through or through. The second partial beam can be deflected by 90°, for example. A semi-transparent mirror is preferably used. The optical device could therefore also be referred to as a "beam splitter" if the beam path is viewed in reverse from the "camera's perspective," i.e., the camera's "visual rays."

[0019] A further development can be characterized in that the optical device comprises a first mirror or, alternatively, a first prism. A further development can be characterized in that the first mirror is a semi-transparent mirror. A further development can be characterized in that the first mirror is a polarizing mirror. A further development can be characterized in that the optical device comprises a second mirror or, alternatively, a second prism.

[0020] A further development can be characterized by the camera being arranged so that it can move. A further development can be characterized by the optical device being arranged so that it can move. A further development can be characterized by the optical device being arranged so that it can move together with the camera. In this way, the device can be adapted when rotating bodies with different radii need to be measured. The movement preferably occurs in a direction that is perpendicular to the tangential direction and the axial direction of the rotating body.

[0021] A further development can be characterized in that the light source comprises a first light source which generates the first partial beam, and in that the light source comprises at least a second light source which generates the second partial beam. A further development can be characterized in that at least one light source is present for illuminating the first point. The light from the first light source can be deflected by a mirror and become the first (measurement) point of the surface to be measured. A further development can be characterized in that at least one second light source is present for illuminating the second point. A further development can be characterized in that the first light source is activated alternately with the second light source. The two images thus generated one after the other on the same image sensor can be evaluated separately using image processing; the evaluation can preferably take place one after the other.

[0022] A further development can be characterized in that the second mirror or the second prism deflects the second partial beam before it reaches the first mirror or the first prism.

[0023] A further development can be characterized in that the first mirror or the first prism is only arranged in one section of the field of view of the camera (relative to the cross-section of the field of view), e.g. in one half of the field of view. In this way, the light from the radial measurement and the light from the tangential measurement can reach the camera or its image sensor at the same time. For this purpose, the first and the second light source are preferably activated simultaneously. A further development can be characterized in that the first partial beam is guided past the first mirror and that the second partial beam is directed towards the first mirror and deflected by it. A further development can be characterized in that the first partial beam reaches a first section of the image sensor and the second partial beam reaches a second section of the image sensor.The two images thus generated simultaneously and preferably side by side on the image sensor can be evaluated separately using image processing; the evaluation can preferably be carried out simultaneously. The two sections are preferably located directly next to each other.

[0024] A further development can be characterized in that the first mirror or the first prism is located outside the beam path between the first point and the camera during the (tangential) measurement at the first location, and in that the first mirror or the first prism is located inside the beam path between the second point and the camera during the (radial) measurement at the second location. It can preferably be provided that the first mirror is not semi-transparent and is movable / positionable and instead is moved away from the field of view of the camera or from the first and second partial beams for the tangential measurement (preferably pivoted or moved linearly) and then moved back into position or into the field of view or into the first and second partial beams for the radial measurement. In this way, only one partial beam reaches the camera at a time. With this solution, the camera preferably remains in one place during the two measurements, i.e.It is not moved. However, this approach takes more time than the inventive approach of parallel measurement; compared to serial measurement, it takes about the same amount of time.

[0025] Preferred developments of the invention are described below as methods (hereinafter referred to as "developments"). These can also be combined with one another where not technically mutually exclusive.

[0026] A further development can be characterized in that the first partial beam captures information on the local height of the surface. A further development can be characterized in that the surface is captured so completely that a complete height profile of the surface is created by computation. A further development can be characterized in that the second partial beam captures information on the local presence of printing and non-printing areas of the surface. A further development can be characterized in that the surface is captured so completely that a complete pressure profile of the surface is created by computation.

[0027] The features and combinations of features disclosed in the above sections Technical Field, Invention and Further Developments as well as in the following section Exemplary Embodiments represent - in any desired combination with one another - further advantageous developments of the invention. Embodiments of the invention and figures The Fig. Figures 1 to 3 show preferred embodiments of the invention and its further developments. Corresponding features are provided with the same reference numerals in the figures. Recurring reference numerals have been partially omitted for clarity.

[0028] The Fig. 1 to 3 each show a schematic representation of a sectional view of a preferred embodiment of the device according to the invention when carrying out the method according to the invention; Fig. 2 and Fig. 3 in simplified representation.

[0029] Fig. 1 shows a device 1. This device is used to measure a rotatable body of rotation 2, in particular a measuring cylinder with a sleeve 3 pushed on it and printing form(s) 4 mounted thereon. The rotation takes place around a rotation axis 5 (which defines the axial direction mentioned in this application). The printing form 4 has a radius 6, wherein, with regard to Fig. 2 and Fig. 3 shows that the radius can vary during successive measurements (radius 6 and a different radius 7). Rotation is achieved by means of a drive, specifically motor 8.

[0030] The rotating body 2, here the printing form 4, comprises a surface 10. Two regions 11a and 11b of this surface are to be measured simultaneously or at least in a timely manner, with the regions "moving" across the surface due to the rotation. In region 11a, there is a first point 12 to be measured; in region 11b, there is a second point 13 to be measured. The two points 12 and 13 can extend in the axial direction, i.e., they can be measuring lines. At point 12, the local height 14 of the surface 10 is to be measured; at point 13, the measurement is to determine whether these are printing points 15 or non-printing points 16.

[0031] Illumination is provided by at least one light source 20. This emits light 21, which is optically captured. An optical camera 30 with a field of view 31 is used. The camera 30 comprises at least one optical chip 32. In the case of tangential measurement (see below), illumination is provided either by the first light source 20a (from "above") via a mirror 27 or, alternatively, by the first light source 20a (from "below") without a mirror; in the case of radial measurement (see below), illumination is provided by the two second light sources 20b, with the latter preferably being activated alternately, thereby generating changing illumination scenarios and thus shadows for capture and evaluation. The light from the first light source 20a reaches the camera 30 via the first optical path 23; the light from the second light sources 20b via the second optical path 24.

[0032] The camera 30 is movably mounted for measuring various printing forms 4. The movement is driven by a second motor 50 and a spindle 51. The camera is preferably mounted on a support 52, which can be moved back and forth in direction 72 as the spindle 51 rotates.

[0033] The device 1 comprises an optical device 40, which, according to the illustrated embodiment, has a first mirror 44 and a second mirror 45. The first mirror 44 is preferably arranged on the support 52—like the camera 30—and is thus movable together with the camera 30b in the direction 72. The second mirror 45 is preferably arranged in a stationary manner.

[0034] The device 1 can be part of a measuring device 60, for example, a so-called mounter. According to the invention, the device 1 is used to perform a measurement of at least one printing form 4 in the tangential direction 70 and, simultaneously or at least concurrently, a measurement in the radial direction 71. The printing form 4 measured in this way can then be used in a printing press 61 on a cylinder 62 for printing, preferably together with the sleeve 3.

[0035] Fig. 2 shows the same device 1 once when measuring a printing form 4 with a first radius 6 (illustration A) and once when measuring a printing form 4 with a different, in particular smaller, second radius 7 (illustration B): accordingly, printing forms with larger radii can also be measured.

[0036] In illustration A, light 21 for the tangential measurement reaches the first point 12 and from there through the semi-transparent first mirror 44 (unreflected) to the camera 30 or the image sensor 32; likewise, light 21 for the radial measurement reaches the second point 13 and from there, reflected at the second point 45 and the semi-transparent first mirror 44, to the camera 30. In illustration B, it can be seen – through the comparative, dotted representation of the camera 30 and the first mirror 44 – that the camera 30 with its image sensor 32 and together with the first mirror 44 has been moved slightly (to the left) and thus positioned. In this way, a printing form 4 with a smaller second radius 7 or its surface 10 can be measured. The first optical path 23 from the first location 12 to the camera 30 and the second optical path 24 from the second location 13 to the camera 30 each remain the same length when the camera 30 is repositioned.The first path length change 25 (decrease) in the second partial beam 43 and the second path length change 26 (increase) in the second partial beam 43 compensate each other. For measurement, the first light source 20a is activated alternately with the two second light sources 20b. Thus, (measurement) light 21 from the first (measurement) point 12 and the second (measurement) point 13 alternately reaches the image sensor 32. The evaluation of the image sensor 32 or the recorded images is therefore preferably also carried out alternately.

[0037] Alternatively, the first mirror 44 may not be semi-transparent and movable, e.g. horizontally, and moved out of the beam path 21 for the tangential measurement of the first location 12 and moved into the beam path 21 for the radial measurement of the second location 13.

[0038] Fig. Figure 3 shows a similar device 1, once during the measurement of a printing form 4 or its surface 10 with a first radius 6 (illustration A) and once during the measurement of a printing form 4 with a different, in particular smaller, second radius 7 (illustration B). The structure is largely the same as in Fig. 2. However, it can be seen that the image sensor 32 is divided into a first section 33 and a second section 34. This division is preferably not of a physical nature, but is merely realized in the evaluation of the data of the image sensor 32. The first mirror 44 is located only in the beam path of the second optical path 24, but not in the beam path of the first optical path 23 (in comparison to Fig. 1, the mirror 44 is positioned only in a section 22 of the camera field of view - restricted to the second section 34). Otherwise, the measurement is carried out in the same way as in Fig. 2 and as can be seen from the two diagrams A and B of the Fig. 3 can be seen in comparison: the camera 30 and its image sensor 32 with the two sections 33 and 34 are moved in direction 72 and positioned for the measurement, with the first optical path 23 and the second optical path 24 again remaining the same length. The light sources 20a and 20b are preferably activated simultaneously: the tangential measurement is performed with the first image sensor section 33; the radial measurement simultaneously with the second image sensor section 34. List of reference symbols 1 device 2 rotating bodies, in particular measuring cylinders with sleeve and printing form(s) 3 sleeve 4 Printing form 5 Rotation axis 6 first radius 7 second radius 8 first motor (rotation of the rotating body) 10 Surface 11a Area of ​​the surface 11b Area of ​​the surface 12 first place of the surface 13 second place of the surface 14 local height of the surface 15 printing positions 16 non-printing positions 20 light source 20a first light source 20b second light source 21 Light or ray path of light 22 Section of the camera field of view 23 first optical path 24 second optical path 25 first change in path length 26 second path length change 27 mirrors 30 Camera 31 field of view 32 image sensor 33 first section 34 second section 40 optical device 41 partial beams 42 first partial beam 43 second partial beam 44 first mirror, alternatively first prism 45 second mirror, alternatively second prism 50 second motor (translation of the camera and the mirror) 51 spindle 52 supports for camera and mirror 60 measuring device, especially mounter 61 printing press 62 rotation bodies 70 tangential direction 71 radial direction 72 Direction of movement

Claims

[1] Device for detecting the surface of a rotary body for a printing press, wherein the rotary body (2, 62) is a) a cylinder, b) a roller, c) a sleeve for a cylinder or for a roller or d) a sleeve for a cylinder or for a roller with at least one printing form arranged on the sleeve, with a motor (8) for rotating the rotary body (2, 62) about an axial rotation axis (5), with at least one light source (20) which illuminates at least one area (11a, 11b) of the surface (10) with optical light (21), and with at least one optical camera (30) for detecting at least the illuminated area (11a, 11b) of the surface (10), characterized by , that the device (1) comprises an optical device (40) which directs the light (21) of two partial beams (41), ie of a first partial beam (42) and a second partial beam (43), to an image sensor (32) of the camera (30), that the first partial beam (42) hits or touches the surface (10) tangentially at a first point (12) and then reaches the camera (30), and that the second partial beam (43) radially hits the surface (10) at a second location (13) - different from the first location (12) - and then reaches the camera (30). [2] Device according to claim 1, characterized by that a first optical path (23) of length L1 from the first location (12) to the camera (30) and a second optical path (24) of length L2 from the second location (13) to the camera (30) have the same length, ie L1=L2. [3] Device according to one of the preceding claims, characterized by that the optical device (40) comprises a first mirror (44) or a first prism (44). [4] Device according to claim 3, characterized by that the first mirror is a semi-transparent mirror (44). [5] Device according to one of the preceding claims 3 or 4, characterized by that the optical device (40) comprises a second mirror (45) or a second prism (45). [6] Device according to claim 5, characterized by that the second mirror (45) or the second prism (45) deflects the second partial beam (43) before it reaches the first mirror (44) or the first prism (44). [7] Device according to one of the preceding claims, characterized by that the light source (20) comprises a first light source (20a) which generates the first partial beam (42), and that the light source (20) comprises at least one second light source (20b) which generates the second partial beam (43). [8] Device according to claim 7, characterized by that the first light source (20a) is activated alternately with the second light source (20b). [9] Device according to one of claims 3 to 8, wherein claim 7 is dependent on one of claims 3 to 6, characterized by that the first mirror (44) or the first prism (44) is arranged only in a section of the field of view (31) of the camera (30). [10] Device according to claim 9, characterized by that the first partial beam (42) is guided past the first mirror (44) and that the second partial beam (43) is directed towards the first mirror (44) and deflected by it. [11] Device according to one of claims 9 or 10, characterized by that the first partial beam (42) reaches a first section (33) of the image sensor (32) and the second partial beam (43) reaches a second section (34) of the image sensor (32). [12] Device according to claim 8, wherein claim 7 is dependent on any one of claims 3 to 6, characterized bythat the first mirror (44) or the first prism (44) is located outside the beam path (21) between the first point (13) and the camera (30) during the measurement at the first point (12), and that the first mirror (44) or the first prism (44) is located inside the beam path (21) between the second point (13) and the camera (30) during the measurement at the second point (13). [13] Method for detecting the surface of a rotating body for a printing press, wherein the rotating body (2, 62) is a) cylinder, b) a roller, c) a sleeve for a cylinder or for a roller or d) a sleeve for a cylinder or for a roller with at least one printing form arranged on the sleeve, and wherein a motor (8) rotates the rotating body (2, 62) about an axial rotation axis (5), at least one light source (20) illuminates at least one area (11a, 11b) of the surface (10) with optical light (21) and at least one optical camera (30) detects at least the illuminated area (11a, 11b) of the surface (10), characterized by that an optical device (40) directs the light (21) of two partial beams (41), ie a first partial beam (42) and a second partial beam (43), to the camera (30) in such a way that a first point (12) of the surface (10) is detected tangentially and a second point (13) of the surface (10) is detected radially at the same time. [14] Method according to claim 13, characterized by that information on the local height (14) of the surface (10) is acquired with the first partial beam (42). [15] Method according to claim 14, characterized by that the surface (10) is recorded completely in such a way that a complete height profile of the surface (10) is created by calculation. [16] Method according to one of claims 13 to 15, characterized by that the second partial beam (43) detects information on the local presence of printing and non-printing areas (15, 16) of the surface (10). [17] Method according to claim 16, characterized by that the surface (10) is completely detected in such a way that a complete pressure profile of the surface (10) is created by calculation.

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