HK1062714A - Compact device for imaging a printing form - Google Patents

Description

Compact device for imaging printing plates

Technical Field

The invention relates to an imaging device for printing plates, comprising a number of light sources and a projection optics for generating image spots of the number of light sources on the printing plate, wherein the projection optics comprise at least one macro-optics consisting of refractive optics.

Background

In order to form the structure of the printing forme, in particular of the printing forme, the printing forme present surface is usually first subjected to the action of electromagnetic radiation, in particular heat or light of different wavelengths, in one state, for example the ink-receiving state, when the structure is not formed, on the areas thereof which receive ink and repel ink, in order to produce another state, for example the ink-repelling state, at the affected locations. In order to carry out the exposure of the printing plate in a targeted, precise and rapid manner, a number of individually controllable light sources, in particular laser light sources, are usually operated in parallel, arranged in a row array or matrix, and projected onto the surface of the printing plate by means of a projection optics assembly, which is arranged in the imaging zone of the projection optics assembly.

For the imaging of a printing form on the projection optics of a device of the type in question, a series of requirements are made of the different functions that it is to satisfy in a printing form exposure device or in a printing unit. On the one hand, some projection optics have a global objective which projects a certain number of light sources onto the image point as faultlessly as possible. This part will be referred to in expression as the "macro-optic component" (Makrooptik). On the other hand, other parts of the projection optics or parts of the macro-optics have their own additional functions, for example, the possibility of meeting the focus position adaptation.

The light source array is usually composed of a number of individually controllable diode lasers, preferably single mode diode lasers, which are arranged at a distance from one another, typically equidistantly spaced apart, on a semiconductor substrate and have a common exit surface (IAB, individually controllable diode laser bar) which is precisely defined at the crystal fracture plane. Since the light emission cone angle of the diode laser has different degrees of expansion in two mutually substantially orthogonal planes of symmetry, there is the necessity for optical correction in order to reduce the asymmetrical divergence of the emerging light. Individual adaptations of the opening angle ratios can be made. This correction is carried out on the respective light source with respect to a part of the projection optics, which part is also referred to as micro-optics (Mikrooptik).

The prior art discloses a series of projection optical systems which are dedicated to the projection of diode laser columns which effect the imaging of the image carrier. For example, document US4,428,647 discloses an imaging device with an array of semiconductor lasers, each of which is assigned a lens for divergence correction, which is located in the vicinity of each laser. Then, the light of the semiconductor laser is condensed by an objective lens and focused on an image carrier. An imaging device with individually controllable diode laser arrays is known from document EP 0878773 a 2. The projection optics has a micro-optics and a macro-optics. The macro-optical assembly is a confocal point lens structure telecentric on two sides. DE 10115875.0 of the prior application discloses an imaging device with an array of light sources. The projection optics comprise a micro-optics unit for generating an intermediate virtual image of the light source and a macro-optics unit comprising a combination of a convex mirror and a concave mirror having a common center point of curvature, the so-called open-type (Offner-Typ), and which generates a real image of the intermediate virtual image.

These solutions known from the prior art are common, i.e. require a large installation space in comparison with their function. It is difficult to implement modifications or add additional functions. Since, on the one hand, the installation space in such machines is very limited and, on the other hand, the structure or configuration of the plate exposure apparatus or of the printing apparatus for implementing the imaging apparatus can be changed only rarely, it is necessary to reduce the installation space required for the projection optics without limiting their necessary functions. In addition, the projection optics on the printing press or on the plate exposure installation are subject to vibrations or oscillations, whereby the optical arrangements known from the prior art cannot generally be easily transferred to the plate exposure installation or to a printing unit of a printing press.

Disclosure of Invention

The object of the invention is to provide a compact device for imaging printing plates, which allows simple integration into the installation space provided by the printing units of a printing press.

This object is achieved according to the invention by a printing plate imaging device having the features of claim 1. Further advantageous embodiments of the invention are the features of the dependent claims.

According to the invention, an imaging device for printing plates has a number of light sources and a projection optics for generating image points of the number of light sources on the printing plate. The projection optics comprise at least one macro-optic consisting of refractive optics or optical elements, in particular a number of lenses, the beam path from the light source to the image point passing twice through the macro-optic. In the expression, the term beam path should be understood to mean all beam paths of the number of light sources. In particular the refractive optical component is passed twice. They are refractive optical components that actually contribute to the generation of the number of image points. Compared with a macro-optical component having a primary beam path, the macro-optical component can be made more compact and space-saving with the same functionality by multiple passes or re-passes of the beam path through the macro-optical component. The number of light sources may also be 1, but preferably a plurality of light sources are provided. The light sources may be arranged in a one-dimensional (preferably rectilinear) or two-dimensional array, in particular in a uniform arrangement, preferably in a cartesian arrangement. The light source and the image point form a single-valued functional relationship with each other. The image points are located at positions separated from each other. The image points may be arranged densely or preferably not densely with respect to each other, i.e. they may have a distance which is larger than the minimum distance of the printing points to be set. The distance between adjacent image points on the printing plate in units of the smallest printing point distance is preferably a natural number which is relatively prime to the number of image points (light sources). The printing form is preferably an offset printing form.

Here, the beam path may pass through the macro-optic assembly non-centrally. In particular, the path of the light beam through the macro-optical assembly on the first path is different from the path of the light beam through the macro-optical assembly on the second path. Furthermore, the beam path extends symmetrically to the optical axis of the macro-optical assembly, in particular the first path may extend symmetrically with respect to the second path.

The beam path may pass through the macro-optical element twice in such a way that the first and second principal planes of the macro-optical element are located on one side of the macro-optical element. The macro-optical component may be implemented as follows: the object (a number of light sources) and the image are located on one side of the macro-optic assembly. In other words, the beam path passes through the macro-optic in a first direction on a first path and passes through the macro-optic in a direction opposite the first direction in a second path.

In a preferred embodiment of the imaging device for printing plates, the macro-optical assembly is provided with at least one mirror, in particular a plane mirror. The macro-optical assembly may be implemented such that the beam path passes through the macro-optical assembly in a first direction in a first path until the light reaches the at least one mirror, and then passes through the macro-optical assembly in a second path in a direction opposite to the first direction. The macro-optical component corresponds approximately to a doubly large optical arrangement. In other words, a macro-optic assembly consisting of a number of optical elements is optically multiplied or doubled by one or more mirrors that reflect light into a symmetrical second path through the macro-optic assembly.

In the imaging device of the printing form according to the invention, the macro-optical component may comprise at least one part of an adaptive (adaptiv) optical component or at least one of the associated mirrors may be made adaptive. In particular, at least one of the mirrors is configured to be adaptive, i.e. to have a variable radius of curvature or a variable surface structure. The image width can be changed by changing the curvature radius. The change in the radius of curvature is small relative to the extension of the adaptive mirror. The adaptive mirror may also effect manipulation of the optical wavefront in the beam path through the macro-optic assembly, such as to achieve axial variation of focusing/defocusing. The adaptive mirror may be an adjustable element that compensates for projection errors. The adaptive mirror may be a diaphragm mirror, an electrostatic mirror, a binary piezoelectric mirror, a piezoelectrically actuated (e.g., polish-milled) metal mirror, or the like.

In an advantageous embodiment of the printing plate imaging device according to the invention, the macro-optical arrangement comprises at least one movable lens, which, in turn, may comprise a movable mirror. The movable lens is particularly advantageous because the macro-optic assembly can be kept telecentric despite lens movement. When the stamp or plate is tensioned on the cylinder, this fixing often results in disturbing convexities ("plate bubbles") of the order of up to several 100 micrometers. The plate surface may be outside the useful focal area of the laser beam due to the convex surface, so that this distance from the focal position does not allow the power density of the laser beam to be sufficient to achieve acceptable imaging results.

This can be achieved in a simple manner by a lens which is movable in the macro-optical assembly: the focal position of the laser beam is moved in the optical axis direction (variable focal point). The accuracy requirements for variable focus are created by the depth of field definition of the laser beam. The device according to the invention can perform a function simply combined with the focus movement. The device has a defined distance between the last optical element and the printing plate, wherein the distance is not changed by the movement of the focal point. At the same time a good transformation ratio between the movement path of the movable lens and the change of the focal position can be achieved.

In an advantageous embodiment of the imaging device of the printing form, the light sources are individually controllable lasers. Each light source corresponds to a single addressable imaging channel having an imaging beam. These light sources may in particular emit light in the infrared (preferred), visible or ultraviolet range. In an advantageous further embodiment, the laser can be operated in a regulated and/or pulsed manner at a constant rate (10)^-9) Second, skin (10)^-12) Second or fly (10)^-15) In the second range. In particular, the individually controllable lasers may be diode lasers or solid-state lasers. The individually controllable lasers may be combined in one or more bars, in particular involving one or more individually controllable diode laser bars (IABs), preferably of a single optical mode. A typical IAB comprises 4 to 1000 lasers, in particular 30 to 260 lasers. The lasers are preferably arranged substantially evenly spaced in the IAB, in particular in a straight line (one-dimensional array) or on a grid (two-dimensional array).

In the imaging device for printing plates according to the invention, a micro-optical module can be arranged along the beam path after a number of light sources, which micro-optical module is arranged in front of the macro-optical module along the beam path. For diode lasers, in particular diode lasers in a rod, the micro-optical component is used primarily for adapting the beam diameter: since the diameter of the individual laser beams on the front side of the IAB is small, typically a few microns in the horizontal direction, i.e. the slow axis, and a few microns in the vertical direction, i.e. the fast axis, the adaptation of the beam diameters in both axes needs to be done independently of each other in order to reach the desired diameter on the printing plate, typically a few microns in the horizontal or vertical direction. One would try to achieve as perfect a gaussian laser beam as possible on the fundamental mode, since it has the highest natural depth of field definition and thus the least sensitivity to focal point shifts or convexities ("plate bubbles"). Preferably the laser operates in a single mode. A micro-optical component can be arranged downstream of the individually controllable lasers, by means of which the beam diameter of the light beam emitted by the lasers can be influenced, i.e. adjusted, independently of one another in two mutually orthogonal axes. The image point (intermediate image) of the micro-optical component may be real or virtual. In particular, the micro-optics assembly produces a virtual, magnified intermediate image of a number of light sources, which image is projected through the macro-optics assembly.

It is particularly advantageous in the imaging device for printing plates according to the invention if the light of a number of light sources is incident into the macro-optical assembly via at least one light deflecting element. By this measure the structure can be made more compact. Preferably, a prism is used as a light deflecting element instead of a mirror pair, in order to inject the light of a certain number of light sources into the macro-optical assembly. The adjustment of the beam path through the macro-optical assembly can also be achieved by means of a parrot prism.

In an advantageous embodiment, the macro-optical component of the device according to the invention is telecentric on both sides (telezenristich). In this connection it should be pointed out that telecentricity in the focusing can be maintained, for example, in the macro-optical assembly of the device according to the invention by means of an adaptive mirror or a movable lens. In other words, the object-image distance will be changed by means of the above-described focus movement, wherein the target distance is fixed. By means of a telecentric beam path in the entire region: the image size in the direction orthogonal to the beam propagation (optical axis) cannot or can only be changed to a small tolerance, typically ± 1 micron. Furthermore, it is advantageously provided that: the macro-optical component enables essentially a projection without dimensional changes, particularly preferably a 1: 1 projection. The focal length of the macro-optical assembly is preferably infinite.

In an advantageous embodiment of the device according to the invention, a correction optics for adjusting the image size is arranged behind the macro-optics along the beam path. The correction optics can achieve a high accuracy of the position of the image point and are preferably also used for very accurate adjustment of the image size. Preferably, the corrective optical component is a zoom objective consisting of two lenses. The zoom objective itself is telecentric on both sides, as is the case with macro-optical components. This telecentricity is maintained when the image size is adapted.

In an advantageous embodiment of the device according to the invention, adjacent image points of the number of image points of the light source on the printing plate have a substantially uniform distance a, wherein the distance a is an integer multiple of the minimum printing point distance p. In particular, in an advantageous manner, the number of light sources is n, where n is relatively prime to the number (a/p), so that a redundancy-free interlaced method of imaging the printing plate can be carried out. It is clear that both n and (a/p) cannot be 1 at the same time.

In a preferred embodiment of a printing plate imaging apparatus according to the invention, the printing plate to be imaged can be received on a rotatable cylinder. Alternatively, the surface of a rotatable cylinder can form a printing plate. In other words, the printing plate may be a plate-shaped (having one edge line) or a sleeve-shaped (having two edge lines) printing plate. They may be single-drawn (conventional), re-coatable or re-drawable plates. In the context of the device according to the invention, a printing form is also understood to be a so-called digital printing form. A digital printing plate is a surface that serves as an intermediate carrier for printing ink before it is transferred to a printing material.

In this case, the surface itself is structured into ink-receiving or ink-repelling regions, or the ink is printed only in a structured manner by an image-forming arrangement. The digital printing plate can be structured into areas by interaction with a laser beam, which allow the transfer or not of printing ink onto the printing material or onto an intermediate carrier. The structuring of the digital printing plate can take place before or after the ink is applied to the printing plate. The printing form can also be formed, for example, for use in a thermal transfer process essentially from the printing ink itself.

The imaging device according to the invention can be used particularly advantageously in a printing unit of a plate exposure apparatus or printing press. The printing device may include one or more devices for imaging. Several devices can be arranged in such a way that they can expose partial areas of a printing plate temporally side by side. The printing press according to the invention with one or more printing units according to the invention can be a web-forming material processing machine or a sheet processing machine. A sheet processing machine usually comprises a feeder, a delivery and one or more further processing stations, such as a varnishing unit or a drying unit. A flanging device can be arranged behind the web material processing machine. The printing method on which the printing device according to the invention or the printing press according to the invention is based can be a direct or indirect offset printing method, a flexographic printing method, an offset printing method, a digital printing method or a similar printing method.

In a second aspect, the invention relates to a method for changing the relative position of image points in an imaging device for printing plates relative to the position of a printing plate, the imaging device having a number of light sources and a projection optics for generating image points of the number of light sources on the printing plate, wherein the projection optics comprise at least one macro-optics. The method according to the invention is characterized in that: one lens in the macro-optic is moved and the beam path passes through the macro-optic twice. In the case of using a macro-optical assembly that is traversed twice by the beam path, the object-image distance can be varied by movement of one lens in the macro-optical assembly, wherein the object distance is fixed. In which telecentricity is advantageously maintained. The method according to the invention is preferably carried out with the aid of the imaging device for printing plates described in this description.

Drawings

Further advantages, advantageous embodiments and further configurations of the invention will now be explained with the aid of the following figures and their description. The attached drawings are as follows:

FIG. 1: a view of a preferred embodiment of the projection optics of the printing plate imaging apparatus according to the invention,

FIG. 2: a view of a preferred embodiment of the macro-optical assembly of the printing plate imaging apparatus according to the invention, wherein part a shows a view in the vertical plane and part B shows a view in the horizontal plane,

FIG. 3: a preferred embodiment of the plate imaging device on a plate cylinder according to the invention

A summary view of an embodiment(s) of the invention,

FIG. 4: a schematic representation of a preferred embodiment of the imaging device for the printing plate in the printing unit of a printing press according to the invention.

Detailed Description

Fig. 1 shows a view of a preferred embodiment of the projection optics of a printing plate imaging device according to the invention. The projection optics 18 include along its beam path 22 a micro-optics 34, which emanates from a number of light sources 14, in a preferred embodiment individually controllable diode laser bars (IABs), a prism (porroprism) 48, a macro-optics 20, an objective lens, which creates a 1: 1 image, and a correction optics 50. The projection optics 18 produce a number of image points 16 of the number of light sources 14. The upper left of figure 1 shows the millimeter scale for quantification.

The beam diameters can be influenced independently of one another in two mutually orthogonal directions perpendicular to the propagation direction (optical axis) by means of the micro-optical assembly 34. It can realize the adaptation of the size of the point to be imaged. Fig. 2 illustrates in detail the micro-optic assembly 34, which includes a fast axial lens 36 and a slow axial lens 38. The number of light sources 14 and micro-optical assemblies 34 may be collectively enclosed in a single housing. The Parlo prism 48, or two mirrors, are used to make light incident on the multi-lens 1: 1 objective of the macro-optic assembly 20 and to collimate the beam in the image plane. The inner side of the parlo prism 48 functions as the light deflecting element 46 by total reflection. The macro-optical assembly 20 includes a first lens 56, a second lens 58, a third lens 60, a fourth lens 62, a fifth lens 64, a movable lens 32 (moving direction is indicated by double arrow), and a mirror 30. The lenses and mirrors 30 of the macro-optic assembly are arranged axially symmetrically about the optical axis 24. The beam path 22 does not extend along the optical axis 24, but is not centered or off-axis. The light can be reflected by the preferably highly reflective coated mirror 30 and can be reflected again but symmetrically by the macro-optic assembly 20 about the first path, laterally to the optical axis 24. In other words, the beam path 22 is folded through the macro-optic assembly 20. The first main plane 26 and the second main plane 28 of the macro-optical component 20 are located-in particular symmetrically-on one side of the macro-optical component 20. In the preferred embodiment shown in fig. 1, a parrot prism 48 is provided in front of macro-optic assembly 20. The result is that the point of the reflective main plane 27 where the light source 14 is located is projected onto the second main plane 28 of the macro-optical assembly 20.

For the adaptation of the focal position of the image point 16, the object-image distance of the macro-optical assembly 20 traversed twice by the beam path is expediently changed. This is achieved in this embodiment by the movement of the movable lens 32. Since a good transfer ratio between the movement of the movable lens 32 and the change in the focal position of the image point 16 is achieved by two passes and by a suitable design of the macro-optical assembly 20, a movement of a distance s will cause a change in the position of m s, where m > 1. The beam path through the macro-optic assembly 20 is telecentric. In order to correct the image size finely, a telecentric correction optics 50 having a first lens 52 and a second lens 54 is arranged downstream of the macro-optics 20 in the embodiment shown in fig. 1. The telecentric correction optics 50 is a two-lens zoom objective which allows stepless adjustment of the image size in the range of plus and minus a few percent, e.g., 0.9 to 1.1.

Fig. 2 is a view of a preferred embodiment of a macro-optic assembly of a printing plate imaging apparatus according to the present invention. In the partial diagram a, a view in the vertical plane is shown, wherein the vertical direction 42 and the horizontal direction 40 out of the plane of the drawing are shown; while part B shows a view in the horizontal plane showing the horizontal direction 40 and the vertical direction 42 into the plane of the drawing. The upper left of fig. 2A and 2B each show a millimeter scale for quantification. In the preferred embodiment, the micro-optic assembly 34 is comprised of a fast axial lens 36 and a slow axial lens 38. The fast axis lens 36 is a single-sided polished glass fiber that is used to reduce the divergence of all of the light beams of a certain number of light sources 14 in its fast axis. The slow axial lenses 38 are arrays of a number of cylindrical lenses corresponding to the number of light sources, wherein each single lens is used to reduce the divergence of the light beam of the light source 14 corresponding to the lens. The micro-optical module 34 is designed such that it produces a virtual intermediate image 44.

Fig. 3 is a schematic view of a preferred embodiment of an imaging device for printing plates on a plate cylinder according to the invention. An imaging device 10 for a printing plate 12 received on a plate cylinder 66 is shown in fig. 3. The light beam of some light sources 14, here single rod-type controllable diode lasers, is shaped by means of a micro-optical assembly 34 and then incident into a macro-optical assembly 20 with a mirror 30 by means of a parrot prism 48. The beam path 22 passes twice through the macro-optics assembly 20 and then through one of the corrective optics assemblies 50. Light source 14 will project onto printing plate 12 at image point 16. In order to compare the focal positions of the projection optics of imaging device 10 to determine the position of printing plate 12, a triangulation sensor 68 is incorporated. The sensor light 70 is reflected at the surface of printing plate 12, from which the distance can be determined. The plate surface may have a pronounced convexity ("platebble") on the order of several 100 microns, whereby a change of the focal position will be performed by the movable lens 32. Triangulation sensor 68 may measure at a location on plate 12 that reaches the image area of image point 16 at a later time by the rotation of plate cylinder 66 in rotational direction 80. It may also refer to a position offset from the image point 16 in the axial direction of the plate cylinder 66. A number of light sources 14 are connected to a laser driver 72, which is functionally connected to a control unit.

Fig. 4 shows a schematic view of a preferred embodiment of a plate imaging device in a printing unit of a printing press according to the invention. An imaging device 10 for printing plates 12 on a plate cylinder 66 is arranged in a printing unit 88 of a printing press 90. For example, three imaging beams 76 produce three image points 16 in an image area 82 of printing plate 12. The plate cylinder 66 is rotatable about its axis 78 in a rotational direction 80 and the imaging device 10 is movable in a translational direction 86 parallel to the axis 78. The line drawn through each image point 16 is preferably oriented substantially parallel to the axis 78 of the plate cylinder 66. The printing points are produced on the printing plate 12 by image points 16 which, under the combined action of the rotation of the plate cylinder 66 and the translation of the imaging device 10, are guided along a helical path 84 (spiral line) over the two-dimensional surface of the printing plate 12.

The feed in the direction of translation 86 and the rotation in the direction of rotation 80 are preferably coordinated in such a way that printing plates 12 are swept redundantly in such a way that densely arranged printing points can be provided. In order to ensure that the areas of the two-dimensional surface of a printing plate 12 on which printing dots are arranged by means of image dots 16 are scanned with imaging beams 76 (irrespective of whether they are arranged on one or more imaging devices) without redundancy, a certain feed adjustment is taken into account for the passage from the position imaged in the preceding step to the position imaged in the subsequent step. Especially when n printing spots are provided in one imaging step by n imaging beams 76 at positions which are not closely located on printing plate 12, i.e. at a printing spot distance p (typically 10 μm) at which their distance is not the smallest, feed adjustment needs to be particularly strictly fulfilled. If the orientation angle of the printing plate is taken into account, a tight imaging can be achieved when the printing dots are arranged in a temporally subsequent step between the imaged printing dots. This scheme is also known under the concept of the "interlacing" method. For example, given in document DE 10031915 a1 or document US2002/0005890a1, the disclosure of which is incorporated herein by reference, the interlaced scanning method for plate exposure is characterized by: given a minimum print point distance p, for a row of n image channels on a straight tensioning line with a uniform distance from one another, their adjacent image points on the printing plate have a distance a which is a multiple of the minimum print point distance p, it being possible to ensure a non-redundant feed of the distance (np) in the direction of the straight tensioning line when the natural numbers n and (a/p) are relatively prime (tailerfriemd). Consideration of the interpolation rule will result in a spiral-like path 84 of picture points that are interleaved with each other. Along an azimuthally tensioned line, a picture point 16 on one spiral path 84 will be disposed between picture points 16 of the other spiral path 84 that have been disposed at a previous time. The printing forme 12 is preferably imaged in the printing couple 88 according to the invention using the imaging device 10 according to the invention in an interlaced scanning method, in particular the interlaced scanning method described in document DE 10031915 a 1.

Claims (25)

1. Imaging device (10) for a printing form (12), having a number of light sources (14) and a projection optics assembly (18) for generating image points (16) of the number of light sources (14) on the printing form, wherein the projection optics assembly (18) comprises at least one macro-optics assembly (20) consisting of refractive optics (32, 56, 58, 60, 62, 64), characterized in that: a beam path (22) from the light source (14) to the image point (16) passes twice through the macro-optical assembly (20).

2. An imaging device (10) for a printing form (12) according to claim 1, characterized in that: the beam path (22) is non-central.

3. Imaging device (10) of a printing form (12) according to claim 1 or 2, characterized in that: the beam path (22) extends symmetrically to the optical axis (24) of the macro-optical assembly (20).

4. Imaging device (10) of a printing form (12) according to one of the preceding claims, characterized in that: the first principal plane (26) and the second principal plane (28) of the macro-optical component are located on one side of the macro-optical component (20).

5. Imaging device (10) of a printing form (12) according to one of the preceding claims, characterized in that: at least one mirror (30) is associated with the macro-optical component (20).

6. An imaging device (10) for a printing form (12) according to claim 5, characterized in that: the macro-optical component (20) comprises at least one adaptive-optics-component-made part or at least one mirror (30) made adaptive.

7. Imaging device (10) of a printing form (12) according to one of the preceding claims, characterized in that: the macro-optical assembly (20) includes at least one movable lens (32).

8. Imaging device (10) of a printing form (12) according to one of the preceding claims, characterized in that: the light sources (14) are individually controllable lasers.

9. An imaging device (10) for a printing form (12) according to claim 8, characterized in that: the individually controllable lasers (14) are diode lasers or solid-state lasers.

10. Imaging device (10) of a printing form (12) according to claim 8 or 9, characterized in that: individually controllable lasers (14) are combined in one rod.

11. Imaging device (10) of a printing form (12) according to one of the preceding claims, characterized in that: a micro-optical module (34) is arranged behind a number of light sources (14) and in front of the macro-optical module (20).

12. Imaging device (10) of a printing form (12) according to claim 8, 9 or 10, characterized in that: a micro-optical assembly (34) is arranged downstream of the individually controllable lasers (14), through which the beam diameter of the light beam emitted by the lasers can be influenced independently of one another in two mutually orthogonal axes.

13. Imaging device (10) of a printing form (12) according to claim 11 or 12, characterized in that: the micro-optic assembly (34) generates a virtual intermediate image (44) which is projected through the macro-optic assembly (20).

14. Imaging device (10) of a printing form (12) according to one of the preceding claims, characterized in that: light of a number of light sources (14) is incident into the macro-optical assembly (20) via at least one light deflecting element (46).

15. Imaging device (10) of a printing form (12) according to claim 9, characterized in that: light from a number of light sources (14) is incident on the macro-optic assembly (20) through a prism (48).

16. Imaging device (10) of a printing form (12) according to one of the preceding claims, characterized in that: the macro-optical assembly (20) is telecentric on both sides.

17. Imaging device (10) of a printing form (12) according to one of the preceding claims, characterized in that: the macro-optical assembly (20) achieves a substantially 1: 1 projection.

18. Imaging device (10) of a printing form (12) according to one of the preceding claims, characterized in that: a correction optical unit (50) for adjusting the size of the image is arranged behind the macro-optical unit (20).

19. An imaging device (10) for a printing form (12) according to claim 15, characterized by: the correction optics assembly (50) is a zoom objective consisting of two lenses (52, 54).

20. Imaging device (10) of a printing form (12) according to one of the preceding claims, characterized in that: adjacent image points (16) of the number of image points (16) of the light source (14) on the printing plate (12) have a substantially uniform distance a, wherein the distance a is an integer multiple of the minimum printing point distance p.

21. An imaging device (10) for a printing form (12) according to claim 20, characterized in that: the number of light sources (14) is n, where n is relatively prime to the number (a/p).

22. A printing device (88), characterized in that: imaging device (10) provided with at least one printing form (12) according to one of the preceding claims.

23. A printing press (90), characterized by: at least one printing unit (88) according to claim 22 is provided.

24. Method for changing the position of an image point (16) relative to the position of a printing plate (12) in an imaging device (10) for the printing plate (12) having a number of light sources (14) and a projection optics unit (18) for generating the image points (16) of the number of light sources (14) on the printing plate, wherein the projection optics unit (18) comprises at least one macro optics unit (20), characterized in that: a lens (32) in the macro-optical assembly (20) is moved through which the beam path (22) from the light source (14) to the image point (16) passes twice.

25. A method of changing the position of a picture element (16) with respect to the position of a printing plate (12) according to claim 24, characterized in that: imaging device (10) using a printing form (12) according to one of claims 1 to 21.