EP0802047A1 - Half tone screen and method and means for its realisation - Google Patents

Abstract

The method involves engraving a template pattern hole structure in a template pattern region (2) of a template base body to form a template pattern (3). Several uniform reference hole structures (4) with different degrees of transmissivity are laser engraved into the template base body outside the template pattern region. The degree of transmissivity of each reference hole structure is compared with each of several desired degrees of transmissivity and the structures are newly engraved depending on the deviations so that deviations are reduced. The process is performed stepwise at least once.

Description

The invention relates to a method for producing a halftone stencil according to the preamble of patent claim 1, a device for carrying out the method according to the preamble of patent claim 15 and a halftone stencil produced according to the method according to the preamble of patent claim 22.

Stencils for textile printing which, for example and due to the pattern to be produced, apply different amounts of color per unit area (halftone printing) are generally known.

With halftone printing, however, there is the difficulty that many settings of operating parameters, both on the engraving device used to produce the stencil and on the printing press, are left to the judgment and skill of the engraver or the printer, and consequently, in the area of halftone printing, unintended, strong deviations from the desired intensity curve of the halftone print arise. So z. B. by halftone stencils that are not with the nominally correct opening conditions were engraved, or due to an inadvertently incorrectly set printing machine or one of the printing stations, some of the colors are applied with the wrong intensity. Particularly in the case of polychromatic prints, this immediately leads to a sensitive disturbance of the color reproduction, which means nothing other than that the colors whose correct reproduction is based on the exact proportions of the individual components being reproduced in completely wrong colors.

The invention has for its object to provide halftone stencils or to provide a method for their production, with which halftone printing can be carried out more accurately or more true to color. The aim of the invention is also to provide a device suitable for producing such halftone stencils.

A method according to the invention is characterized in that a plurality of uniform reference hole structures, which each have different degrees of permeability, are engraved into the template base body and lie outside the template pattern area.

The reference hole structures can also be referred to as halftone marks or area marks. These reference hole structures or surface marks can lie directly against one another, but can also be spaced apart or separated from one another.

According to the invention, in addition to a print mark (Pico) that may already be present, the aforementioned reference hole structures are generated at the edge of the halftone stencil, with which certain predetermined color intensities are to be achieved when printing with the stencil. These reference hole structures consist of small areas, e.g. B. squares, rectangles or circles, which are engraved with different but predetermined permeability and with a nominally correct permeability and with the correct setting of all parameters on the printing machine when printing later with such a halftone stencil, a defined and therefore verifiable sequence of color intensity values from the intensity range from 0 to 100%.

By checking the intensity values of the print images obtained with the aid of the reference hole structures and possibly by changing the printing parameters depending on the result of the check, an improved halftone print can also be achieved in the template pattern area, since the template pattern hole structure present there in relation to the reference hole structure (both need not necessarily be identical) ) stands.

According to an advantageous development of the invention, the degree of permeability of each reference hole structure is compared with a respective desired degree of permeability in order to re-engrave the uniform reference hole structures depending on the respective deviation in such a way that the mentioned deviation is reduced, this sequence of steps being carried out at least once.

The advantage of this measure can be seen in the fact that the parameter "degree of permeability" can be brought to its target value (or at least approximated to it) even before the actual printing, so that later the actual printing parameters no longer change to such a large extent need to be, which might not be possible under certain circumstances, in order to arrive at the desired color intensities for the respectively given permeability levels (target permeability levels). The nominally correct opening ratio of the halftone stencil is to be understood here as the target degree of permeability. The actual degree of permeability then relates to the actually achieved opening ratio of the halftone stencil.

According to another advantageous development of the invention, the template pattern hole structure lying in the template pattern area is engraved as a function of the above-mentioned deviations. If the actual permeability differs from the target permeability, not only is the new reference hole structure re-engraved, but the engraving parameters are also changed in order to achieve an improved template pattern hole structure. As already mentioned, the degrees of permeability in different areas of the template pattern hole structure do not necessarily have to be identical to the degrees of permeability of the reference hole structures. The former are rather related to the latter, so that when changed of the degree of permeability of the reference hole structure as a result of a deviation from the corresponding target permeability is also to be changed accordingly.

According to one embodiment of the invention, the respectively old reference hole structures are eliminated after their degree of permeability has been compared with the target degree of permeability. The old reference hole structures can be removed before new ones are engraved. The elimination is e.g. B. possible by simply cutting off the old reference hole structures from the template body. However, it is more advantageous to paint over them and to engrave new reference hole structures in the corresponding areas.

According to a very advantageous further embodiment of the invention, the degree of permeability of a respective reference hole structure is measured automatically. In principle, the comparison between permeability and target permeability of a respective reference hole structure can be made visually, i.e. by the engraver. However, an automated control is more useful because it can be carried out faster and more precisely. For the visual comparison, the reference hole structures must also be relatively extensive, i.e. the rectangles, squares or circles already mentioned at the beginning, for example, must be relatively large. The respective reference hole structure then comprises a large number of template openings. However, if the degree of permeability is measured automatically, this can be done by using relatively fewer template openings or smaller reference hole structures, which saves time and space on the template base body.

As a template body z. B. a sieve can be used, on which a cover layer comes to rest, which leaves the sieve openings free to form a reference hole structure at least in certain areas.

The covering layer can be a lacquer layer covering the sieve, which is burned away in regions with the aid of a laser beam in order to expose the sieve openings. It can also have polymerizable properties in order to be achieved by point exposure by means of e.g. B. to be cured by a laser beam. The unexposed are then exposed in a subsequent development process Areas of the varnish layer removed to expose the screen openings. However, if it has polymerizable properties, the covering layer can also be covered point by point with the aid of a liquid which is opaque. This is followed by a large-area exposure and curing of the uncovered layer areas and then a development process to remove the unhardened layer areas. Alternatively, the lacquer layer can also be produced by spraying a liquid covering material onto the screen using a nozzle. Wherever stencil openings are to be created, the nozzle is switched off.

In addition, a template with a closed surface can be used as the template base body, on which a covering layer comes to lie, which leaves the surfaces exposed in regions to form the reference hole structure.

Here, too, the cover layer can be produced by burning it away using a laser beam, by spot exposure and subsequent development (if it can be polymerized) or by spraying liquid onto the surface of the template base body with the aid of a nozzle. Likewise, here too, the covering layer can first be covered point by point with liquid which is opaque. A large-area exposure can then again be carried out in order to harden the layer regions not covered by the liquid. Then there is a development process for removing the uncured layer regions.

After the covering layer with the corresponding several reference hole structures has been completed, these are measured in order to determine the degree of permeability of the respective reference hole structures. If the degree of permeability finally agrees with the target degree of permeability or if it has been sufficiently approximated, metallic material is applied to the cover layer in order to obtain a sieve, which is then removed from the template base body. Is this z. B. made of nickel, nickel can be galvanically deposited on its surface to form sieves. The finished screen then contains not only the multiple reference hole structures, but also the finished template pattern.

In the case of a sieve that is present from the outset, the permeability becomes the reference hole structure is measured by means of a light beam passing through the screen openings, which is essentially perpendicular to the stencil surface and can penetrate it in one direction or the other. The light beam is focused, with the focus being on the stencil surface.

Alternatively, the degree of permeability of the reference hole structure can also be measured in this case by means of a gas flow passing through the sieve openings.

In the case of a template base body with a closed surface, the degree of permeability of the reference hole structure in the lacquer layer lying on this surface is measured by means of a light beam reflected on the exposed surface. Depending on the size of the openings belonging to the reference hole structure, the amount of the reflected intensity changes, which is a measure of the size of these openings. However, it must be taken into account here that the sieve openings of the sieve which is subsequently applied come to lie where the cover layer material is still present during the measurement. This must be taken into account when determining the degree of permeability.

If, after measuring the degree of permeability, it is found that this differs from the target degree of permeability, then depending on the manufacturing variant, the pulse ratio of the laser beam or an on / off cycle of the nozzle spraying the liquid are preferably changed in order to adjust the degree of permeability to the target degree of permeability.

In a development of the invention, the stencil base body can be designed as a hollow cylinder, so that halftone rotary printing stencils can also be produced by the method according to the invention.

A device according to the invention for producing a halftone stencil contains a bearing device for rotatably supporting a hollow cylinder; means for machining the outer peripheral surface of the hollow cylinder; a slide which can be displaced parallel to the hollow cylinder axis and carries at least part of the processing device; and a control device for controlling the processing device and for moving the carriage with rotating hollow cylinder. This device is characterized in that it has a measuring device for measuring the degree of permeability of reference hole structures located in a predetermined template area.

The reference hole structures are preferably located at only one end of the hollow cylinder, so that the location of the measuring device is selected accordingly. You can therefore z. B. attached to the storage facility.

Last but not least, a halftone stencil with an approximately central stencil pattern area is characterized in that it has a plurality of uniform reference hole structures, each with a different degree of permeability, outside the stencil pattern area. The halftone stencil can be hollow-cylindrical in order to obtain a rotary printing stencil. The reference hole structures can lie directly on one another or be arranged separately from one another.

It should be pointed out again that the term reference hole structure is understood to mean an area in which there are a plurality of uniformly or uniformly opened sieve openings or a plurality of uniform or uniform structures which serve to form sieve openings. In the case of sieve openings, the different degrees of permeability are achieved in that these sieve openings are more or less covered by the cover layer. In the case of the structures mentioned for forming the sieve openings, different degrees of permeability are achieved in the sieve to be formed later by making the structures more or less wide.

Fig. 1

eine Halbton-Rotationsdruckschablone mit mehreren Referenzlochstrukturen jeweils unterschiedlichen Durchlässigkeitsgrads;

Fig. 2

eine Rotationsdruckmaschine, bei der Halbton-Rotationsdruckschablonen nach Fig. 1 zum Einsatz kommen:

Fig. 3

eine Laser-Gravieranlage zur Herstellung der in Fig. 1 gezeigten HalbtonRotationsdruckschablone;

Fig. 4

einen Axialschnitt durch den rechten Lagerbereich der Laser-Gravieranlage nach Fig. 3;

Fig. 5

eine optische Reflexions-Meßeinrichtung zur Ausmessung des Durchlässigkeitsgrads einer Referenzlochstruktur auf der Oberfläche eines Schablonenrohlings, auf den zur Bildung einer Siebdruckschablone metallisches Material galvanisch aufgebracht wird: und

Fig. 6

einen Axialschnitt im rechten Lagerbereich der Laser-Gravieranlage nach Fig. 3 mit einem strömungstechnisch arbeitenden Meßgerät zur Messung des Durchlässigkeitsgrads einer Referenzlochstruktur.

The drawing shows exemplary embodiments of the invention.

Fig. 1

a halftone rotary printing stencil with several reference hole structures, each with a different degree of permeability;

Fig. 2

a rotary printing press in which halftone rotary printing stencils according to FIG. 1 are used:

Fig. 3

a laser engraving system for producing the halftone rotary printing stencil shown in FIG. 1;

Fig. 4

an axial section through the right storage area of the laser engraving system of FIG. 3;

Fig. 5

an optical reflection measuring device for measuring the transmittance of a reference hole structure on the surface of a stencil blank, to which metallic material is galvanically applied to form a screen printing stencil: and

Fig. 6

an axial section in the right bearing area of the laser engraving system of FIG. 3 with a fluid dynamics measuring device for measuring the permeability of a reference hole structure.

1 shows a hollow cylindrical rotary printing stencil 1 produced according to the invention for halftone printing, which is equipped in its central part or stencil pattern area 2 with an engraving or stencil pattern hole structure to form a stencil pattern 3. The template pattern 3 has different permeability ratios in different areas. In the present case, the halftone stencil 1 consists of a hollow cylindrical sieve with a covering layer on which the stencil pattern hole structure has been engraved in order to expose sieve openings in the cylindrical carrier sieve at least in some areas.

Outside the template pattern area 2 are z. B. on a front edge of the halftone template 1 area marks 4, each having a uniform reference hole structure, but differ in terms of permeability. 1 shows four surface marks 4, which each have permeabilities of 10, 50, 75 and 100% and are arranged separately from one another. The permeability depends not only on the extent to which the respective screen openings of the cylinder screen located below the cover layer have been exposed, but also on the type and viscosity of the paint that later passes through the stencil openings, on the liquid pressure, etc. The permeability in the area of the area marks 4 Furthermore, they do not have to be identical to those which are present in the respective areas of the template pattern 3.

In addition, a print mark 5 (Pico) is provided, which is realized here by a circular ring. Its task is to assist in the adjustment of several halftone templates to one another in a rotary printing press.

A reference standard can be stopped at the surface marks 4 or uniform reference hole structures shown here for the purpose of visual assessment of the engraving. B. also from paint-coated, engraved sieve pieces, for. B. nickel screen pieces. With such a visual comparison, the engraving system must of course be stopped. However, if the degree of permeability of a respective reference hole structure or area mark 4 is measured automatically, the comparison can be carried out with the engraving system running, that is to say the comparison between the degree of permeability and the desired degree of permeability for the respective area mark 4.

2 shows a rotary printing press 6 on which stencils 1 produced according to the invention are used. In such a machine 6, the stencils 1 are driven by gears 7 and repeat gear 8, so that they run synchronously with the web 9 guided under the stencils 1 by the machine 6. The gear wheels 7 are attached to template heads which are glued into the end faces of the templates 1. The web 9 is glued to the printing blanket 10 with a very easily removable adhesive and held by the printing blanket 10 during printing. The printing blanket 10 is a very wide rubber fabric transport belt; it is driven by two deflecting rollers 11, which are wrapped in the printing blanket 10. With this arrangement, the mentioned synchronous operation between stencils 1 and web 9 to be printed is achieved. The surface marks 4 of each stencil 1 are printed together with the pattern on the web 9 and there result in surface mark images 12. A video camera 13 is mounted at the end of the printing machine 6 on its side wall 14 and continuously measures the color intensities of the surface mark images 12. If there is a deviation in the color tone or the color intensity is determined, then either an acoustic or an optical signal is emitted or the inking unit to be readjusted can be influenced by means of a servomechanism, if there is one.

A laser engraving system is shown in FIG. 3. The template 1 to be engraved is centered and held between two clamping cones 15 and 16. Of the Clamping cone 15 is rotatably driven and mounted in a gear box 17 in which the drive motor is also located. The left end face of the template 1 is pushed onto this. The clamping cone 16 is rotatably mounted in a tailstock 18 and is not driven in this embodiment. The tailstock 18 can be adjusted on guides 19 in the direction of the connecting axis 20 between the two clamping cones 15 and 16 and thus any lengths of the template 1 can be set. Torsionally rigid connected to the clamping cone 15 is an encoder 21 which provides the pulse or rotational position signals for the engraving system computer 22 via a line 21a. For engraving, a laser beam 23, which is emitted from the laser 24, is focused on the surface of the template 1 via deflecting mirrors 25 and an optical system 26. The laser beam 23 is clocked according to the requirements of the pattern 3 via a line 22a by the computer 22, ie switched on or off, and accordingly a lacquer layer 1a is removed from the cylinder screen 1b or cured. During the engraving, the template 1 rotates at approximately 500 to 1200 rpm and at the same time a carriage 28, which carries the optics 26, is advanced in the direction of the connecting axis 20 by an invisible feed spindle. The carriage is shifted under the control of the computer 22 via a line 22b.

At the beginning of the engraving work, the area marks 4 are first engraved. These are subjected to an inspection immediately after they have been manufactured, even before the actual pattern 3 is engraved. A measuring or inspection device 27 is attached to the tailstock 18 in this embodiment. However, it may well be expedient to mount this device 27 on the gearbox 17 and then to provide the surface marks 4 on the opposite edge side of the template 1. The inspection device 27 can show one of the designs described in the following figures. Its output signals are transmitted to the computer 22 via a line 22c.

4 shows an inspection device 27 which uses an optical measurement method to determine the degree of permeability of the engraved area marks 4. The tailstock 18 contains not only the tension cone 16 mounted on ball bearings 29, but also a projection device 30 for generating an aerial image 31. This is approximately in the area of the jacket of the template 1. A tube 33 carries a lamp house 32 from its right end Tube 33 is held by a conical clamping sleeve 34 in a matching conical receiving hole in the tailstock 18. A pressure plate 35 presses the clamping sleeve 34 into this receiving bore. A projection lamp 36 is provided within the lamp house 32 and is held by a holder 37. A concave mirror 38 serves to increase the luminous efficiency of the projection lamp 36. A part of the useless emitted light quantity is reflected back into the condenser 39 by this concave mirror 38. A metallic screen 40 contains an aperture in the form of a circle or a square. This aperture 40 is illuminated as evenly as possible by the condenser 39. The aperture is projected through an optic 41 (achromatic) over a deflecting mirror 42 as an aerial image 31 onto the jacket of the template 1. From this aerial image 31, only those points are visible from the outside that fall on the exposed positions of the template 1. A semiconductor camera 44 is carried by a holder 43 on the tailstock 18 and images the visible parts of the aerial image 31 via further optics 45 onto a light-sensitive semiconductor (photo diode, photo transistor, photo resistor) 46. The output signal of this semiconductor 46 triggered by the incidence of light is amplified by an integrated preamplifier 47 and serves as a measure of the permeability of the engraving measured in this way.

FIG. 5 shows a further inspection device 27 'working on an optical basis, which uses the radiation reflected from the area of the area mark 4 to measure the quality of the engraving. This device 27 'is used when the engraving is to be introduced into a layer 1c on a closed (ie not sieve-like) hollow cylinder 1d. The lighting area of a lamp 49 is imaged on the surface of the area mark 4 via an optical system 48 of a lamp house 32. Of course, this lamp house 32 can also be designed to be somewhat more complex - approximately as shown in FIG. 4. In any case, the area mark 4 is illuminated in such a way that the entire area it occupies is illuminated as evenly as possible. The light reflected by the area mark 4 or rather the intensity thereof is measured by the semiconductor camera 44 and used to assess the degree of transmission of the area mark 4. An image of the area mark 4 is projected by the optics 45 onto the light-sensitive semiconductor 46 and its output signal is amplified by the integrated amplifier 47 and passed on to the evaluation unit 22, which is no longer shown.

FIG. 6 shows an inspection device 27 ″ that works in terms of flow technology and is designed as a measuring nozzle for determining the quality of the engraving or the degree of permeability of the surface marks 4. The interior of the template 1 is in this embodiment under a slightly excessive air pressure, approximately in the size of 0.1 to 0.3 bar overpressure. This pressure arises from the supply of compressed air through a hollow shaft 55 which carries the clamping cone 16. A radial fan, which is no longer shown and possibly multi-stage, serves as the source for this compressed air. Although the pressure can only be maintained as long as larger sample areas are not exposed, this compressed air can be provided with little energy as long as long as the area marks 4 are the only open areas of the template 1. However, the engraving of these surface marks 4 must take place at the beginning of the engraving work anyway, because the result of the measurement of these marks 4 must be available before the actual pattern engraving can be carried out for any necessary correction of the setting parameters of the engraving machine. Therefore, the restriction mentioned does not constitute an obstacle. The air emerging from the exposed areas of the area mark 4 is caught by the mouth 49 of the pneumatically operating inspection device 27 ″. The distance of the mouth 49 from the outer jacket of the template 1 is preferably less than 1/4 of the mouth diameter. Then the air collected by the mouth 49 flows through a taper 51 of the flow channel 50. It is known from flow mechanics that the speed increases in the taper and the static pressure drops if the flow channel 50 does not have an opening to the outside here. In this taper there is a first temperature-dependent resistor 52 (NTC resistor) which is arranged as centrally as possible in the channel and which is fastened in such a way that no leaks occur as a result of the fastening. This resistance 52 is greatly cooled here by the high flow rate. The channel 50 is then widened again in a diffuser-like manner so that no high energy losses occur and as much air as possible flows through the measuring nozzle and as little air as possible exits into the outside atmosphere through the gap in front of the mouth 49. A second temperature-dependent resistor 53 (NTC resistor) is then provided in an edge position of the flow channel 50 which is expanded as possible and is protected against flow. This is only washed around by a weak current and cooled only a little. If you switch these two resistors 52, 53 into a half-bridge and add two further resistors to the full-bridge to the half-bridge, you can measure their diagonal voltage use as a measurement signal for the permeability of the engraving of the area mark 4. This device 27 ″ is extremely sensitive even to very low flow velocities. Of course, one can also arrange two temperature-dependent resistors in the tapered and expanded flow channel position and interconnect them in the form of a full bridge, which results in an increase in the measurement signal.

Of course, the amount of air let through the area marks 4 could also be determined via a measuring orifice arrangement known per se or via a likewise known differential pressure load cell. In the latter case, the static differential pressure between the points of the highest and lowest flow velocity of the measuring nozzle shown in Fig. 6 is measured.

Claims (24)

Method for producing a halftone stencil (1), in which a stencil pattern hole structure is engraved in a predetermined stencil pattern area (2) of a stencil base body (1a, 1b; 1c, 1d) to form a stencil pattern (3), characterized in that in the stencil base body (1a, 1b; 1c, 1d) several uniform reference hole structures (4) lying outside the template pattern area (2) are engraved, each having different degrees of permeability. Method according to Claim 1, characterized in that the degree of permeability of each reference hole structure (4) is compared with a respective desired degree of permeability in order to re-engrave the uniform reference hole structures depending on the respective deviation, in such a way that the said deviation is reduced, this sequence of steps is executed at least once. Method according to claim 2, characterized in that the template pattern hole structure lying in the template pattern area (2) is engraved as a function of the above-mentioned deviations. Method according to Claim 2 or 3, characterized in that the respective old reference hole structures (4) are eliminated after their degree of permeability has been compared with the target degree of permeability. Method according to claim 4, characterized in that the old reference hole structures (4) are removed before new ones are engraved. Method according to one of claims 2 to 5, characterized in that the degree of permeability of a respective reference hole structure (4) is measured automatically. Method according to one of claims 1 to 6, characterized in that a sieve (1b) is used as the template base body, on which a cover layer (1a) comes to rest, the sieve openings to form a reference hole structure (4) leaves free at least in certain areas. Method according to one of Claims 1 to 6, characterized in that the template base body used is one (1d) with a closed surface, on which a covering layer (1c) comes to rest, which leaves the surface exposed in certain areas to form the reference hole structure (4). Method according to claims 6 and 7, characterized in that the degree of permeability of the reference hole structure (4) is measured by means of a light beam passing through the screen openings. Method according to claims 6 and 7, characterized in that the degree of permeability of the reference hole structure (4) is measured by means of a gas flow passing through the sieve openings. A method according to claims 6 and 8, characterized in that the transmittance of the reference hole structure is measured by means of a light beam reflected on the exposed surface. Method according to one of claims 2 to 11, characterized in that a laser beam (23) is used to form the reference hole structure (4), the cycle ratio of which is changed in accordance with the deviation between the degree of permeability and the desired degree of permeability of the reference hole structure (4). Method according to one of Claims 2 to 11, characterized in that a nozzle for spraying out covering lacquer is used to form the reference hole structure (4), the on / off cycle of which is in accordance with the deviation between the degree of permeability and the desired degree of permeability of the reference hole structure (4 ) is changed. Method according to one of claims 1 to 13, characterized in that the template base body is designed as a hollow cylinder. Device for producing a halftone stencil with - A bearing device (15, 16) for the rotatable mounting of a hollow cylinder (1a, 1b; 1c, 1d); - A device (24 to 26) for processing the outer peripheral surface of the hollow cylinder; - A slide (28) which can be moved parallel to the hollow cylinder axis (20) and carries at least part of the processing device; and a control device (22) for controlling the machining device and for displacing the slide () 28) when the hollow cylinder is rotating,
characterized in that it has a measuring device (27, 27 ', 27'') for measuring the degree of permeability of reference hole structures (4) lying in a predetermined template area. Apparatus according to claim 15, characterized in that the control device (22) has a comparison device for comparing the measured permeability with a target permeability and the processing device (24 to 26) can be controlled as a function of the comparison result. Apparatus according to claim 16, characterized in that the measuring device (27) has a radiation source (36) for emitting a beam and a radiation detector (47) which are positioned in a transmission arrangement with respect to the hollow cylinder wall. Apparatus according to claim 15 or 16, characterized in that the measuring device (27 ') has a radiation source (49) for emitting a beam and a radiation detector (47) which are positioned in a reflective arrangement with respect to the hollow cylinder wall. Apparatus according to claim 18, characterized in that the radiation source (49) is designed to emit a monochromatic beam. Apparatus according to claim 15 or 16, characterized in that the measuring device has a measuring nozzle (27 ''), which is essentially radially outside to the hollow cylinder (1a, 1b), and that the bearing device (16) with a gas supply channel (55) for Introducing a gas under pressure into the interior of the hollow cylinder (1a, 1b). Device according to one of claims 15 to 20, characterized in that the measuring device (27, 27 ', 27'') is attached to the bearing device (16). Halftone stencil with an approximately central stencil pattern area (2), characterized in that it has a plurality of uniform reference hole structures (4) outside the stencil pattern area (2), each with a different degree of permeability. Halftone stencil according to claim 22, characterized in that it is hollow cylindrical. Halftone template according to Claim 22 or 23, characterized in that the respective reference hole structures are arranged separately from one another.

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