DE102020123695A1 - Device for irradiating a fluid on a printing material - Google Patents

Abstract

A device according to the invention for irradiating a fluid on a printing material, with modules (10) arranged essentially in a row (11) for generating radiation, comprising at least one edge module (12) each at the beginning or at the end of the row and a plurality of inner modules ( 13) inside the row, the modules each comprising at least one LED emitter (14) or LED emitters designed as a UV LED emitter (14), is characterized in that the edge modules (12) are one of the inner Modules (13) have such a different structure that the yield of radiation from the edge modules, which the fluid (9) strikes, is increased compared to at least one inner module. The edge module can have a mirror or an inclined LED spotlight for this purpose.

Description

The invention relates to a device with the features of the preamble of claim 1 or 11.

Technical field of the invention

The invention is in the technical field of the graphics industry and there in particular in the field of drying and / or hardening of printing ink or liquid ink or other printing media / fluids on sheet or web-shaped printing materials, preferably made of paper, cardboard, cardboard, plastic or composite material.

State of the art

The drying and / or hardening (or more generally: the treatment) of preferably liquid or pasty printing media / fluids (such as printing ink, varnish or ink) on a printing material can be done in various ways, which can also be combined: by applying hot air, with electromagnetic radiation (e.g. UV or IR) or particle radiation (e.g. electrons) or by contacting the printing material with heated surfaces (e.g. cylinders, rollers or belts). Water-based printing media are usually dried thermally, preferably with IR, while polymerizable printing media are usually dried with UV. LED emitters are increasingly being used as radiation sources for IR and UV.

A related device for drying and / or curing can have a modular structure, with the modules being able to be arranged next to one another and covering the width of the printing material. each module can have several LED emitters and their chips can be arranged as a two-dimensional field.

Such a page-width device can have a so-called edge drop, i.e. the optical power can drop towards the sides of the printing material. The reason for this is that the beam cones of neighboring modules overlap, but the modules at the edge of the device do not include any (outer) neighbors. The edge drop can cause problems with drying and / or curing.

One solution can be seen in the use of irradiation devices which, although they have an edge drop, which, however, lies outside of the printing material. This solution leads disadvantageously to large devices, installation space problems and lateral overexposure.

LED spotlights are also subject to disadvantageous aging ("degradation"), i.e. their optical performance decreases during the operating time, e.g. from around 5000 operating hours, which can lead to insufficient drying / hardening, especially in the edge area.

The DE 10 2004 020 454 A1 discloses a device for supplying radiant energy to a printing substrate with at least one radiant energy source, the light of which hits the printing substrate on the path of the printing substrate through a printing machine at a position which is arranged downstream of at least one printing nip in a printing unit, and is characterized in that the radiation energy source emits light which has a peak-to-valley homogeneity of less than about 15% in the direction transverse to the direction of the path of the printing material. The radiation energy sources are preferably lasers.

The DE 10 2007 058 957 A1 discloses a method for drying printed material which works with the aid of a one- or two-dimensional array of radiation sources that can be controlled individually or in groups. The high-resolution image data describing the print image or the content of the printing forms are converted into image data of lower resolution for the individual color separations Position data generated control data for modulating the intensity of the radiation sources or groups of radiation sources of the array, so that the printing material is swept over in the transport direction with time-modulated radiation points, each of which comprises several image points of the higher-resolution print image. The radiation sources can be controlled individually. The topic of "edge waste" is briefly mentioned in paragraph 45, but not dealt with further as a problem to be solved.

The US 2004 / 0080938A1 discloses a lighting system with LED spotlights, each of which has four side mirrors. The system is not designed to handle print media.

The US 2011 / 0175533A1 discloses a further lighting system with LED spotlights, which can be arranged inclined. The system is also not used to handle print media.

task

It is therefore an object of the invention to provide an improvement over the prior art which in particular makes it possible to avoid the disruptive edge drop, i.e. the decrease in the optical power of an irradiation device at its edge.

Solution according to the invention

According to the invention, this object is achieved by a device according to claim 1 or 11. Advantageous and therefore preferred developments of the invention emerge from the subclaims as well as from the description and the drawings.

A first device according to the invention for irradiating a fluid on a printing substrate, with modules for generating radiation arranged essentially in a row, comprising at least one edge module each at the beginning or at the end of the row and a plurality of inner modules in the interior of the row, the modules each comprise at least one LED emitter or LED emitters designed as a UV-LED emitter,
is characterized in that the edge modules have a structure different from the inner modules in such a way that the yield of radiation from the edge modules which the fluid strikes is increased compared to at least one inner module.

An alternative second device according to the invention for irradiating a fluid on a printing substrate, with modules for generating radiation arranged essentially in a row, comprising at least one edge module each at the beginning or at the end of the row and a plurality of inner modules inside the row, the modules each comprise at least one LED emitter or LED emitter designed as a UV LED emitter, is characterized in that the edge modules are controlled and / or energized differently compared to the inner modules in such a way that the yield of radiation from the edge modules, which the fluid meets is increased compared to at least one inner module.

The different control and / or energizing of the inner modules (compared to the inner modules) can be referred to as “dimming” these modules.

The invention advantageously makes it possible to avoid the disruptive edge drop, i.e. the decrease in the optical power of an irradiation device at its edge. This makes it possible to achieve optimal drying / hardening results and to produce industrially high-quality printed products.

By increasing the yield of radiation from the edge modules, the otherwise disruptive edge drop can be compensated in an advantageous manner.

By compensating for the disruptive edge waste according to the invention, it is advantageously also possible (due to the variety of parts and cost reduction) to use identical irradiation devices in printing machines with different but similar format widths, e.g. in 102 and 106 format (1020 or 1060 mm sheet width) or also in 92 format. In addition, it is advantageously also possible to operate the irradiation device over a longer operating time than would otherwise be possible.

In addition, irradiation devices with a long service life can also be dimmed sufficiently (for a required radiation homogeneity) in an advantageous manner. The dimming can preferably take place according to a characteristic curve which can be specified by the operating time of the inner modules. The dimming can preferably take place according to a compensation curve, which is calculated, for example, from a recorded degradation. For example, by measuring the ratio (proportional to the optical power) of the current and voltage values on the modules and comparing the measured values between inner modules and edge modules; Modules with a high voltage / current ratio are then dimmed more and those with a low ratio are dimmed less.

Developments of the invention

A preferred development of the first and second device can be characterized in that the modules each comprise i * j substrates or i * j substrates with respective heat sinks and that each substrate comprises at least one LED emitter chip, where i and j ∈ ℕ \ {0}.

A preferred development of the first and second device can be characterized in that the modules or the substrates each comprise an n * m field of LED emitter chips, where n and m ∈ ℕ \ {0}.

A preferred development of the first and second device can be characterized in that the radiation power of each module can be controlled separately or can be controlled separately via the current supply. This enables the edge modules to be dimmed separately (and also a corresponding dimming of the inner modules), preferably to achieve sufficient homogeneity of the optical power of the irradiation device.

A preferred development of the first and second device can be characterized in that the edge module on one of its sides or on two of its sides or on three of its sides, the side / sides not adjoining an inner module, each have a mirror or each a mirror inclined to the plane of the module or in each case a mirror inclined to the plane of the module and rotated about an axis perpendicular to the plane or each comprises a curved mirror. Edge modules preferably have fewer than four side mirrors. Inner modules preferably have no mirrors.

A preferred development of the first and second device can be characterized in that the mirror is formed by a plurality of individual mirrors.

A preferred development of the first and second device can be characterized in that at least one LED emitter or at least one LED emitter with primary optics is inclined or several times inclined to the plane of the module.

A preferred development of the first and second device can be characterized in that the modules each include several LED emitters and that the packing density of the LED emitters on the edge module is increased compared to the packing density of the LED emitters on at least one inner module or the packing density the LED spotlight on at least one inner module is reduced compared to the packing density of the LED spotlights on the edge module. The packing density indicates the number of LED spotlights per unit area, e.g. per square centimeter.

A preferred development of the first and second device can be characterized in that the modules each comprise several LED emitters and that a number of the LED emitters of the edge module are selected from a binning class with a higher yield of radiation compared to at least one inner module or a number of the LED emitters of at least one inner module is selected from a binning class with a lower yield of radiation compared to the edge module.

Regarding the term “binning”: In the production of LEDs, there are manufacturing-related small deviations in color temperatures and brightness values that would be noticeable in a direct comparison (for example when combining several LEDs in one spotlight). By combining radiators with subgroups of LEDs of known intensity, larger groups of the same intensity can be formed again. The exemplary division of the products into the various finely graded classes after production is referred to as "binning", whereby the LEDs are sorted or classified into so-called bins using correspondingly finely graded parameters, i.e. the LEDs are assigned to a group of the same lighting intensity.

A preferred development of the first and second device can be characterized in that the device comprises an element or a drum or a belt for moving the printing material in a transport direction and that the modules are arranged in the row in a lateral direction with respect to the transport direction.

The features of the invention, the developments of the invention and the exemplary embodiments of the invention also represent advantageous developments of the invention in any combination with one another. Further developments of the invention can also have the individual features or combinations of features disclosed in the above section “Technical Field of the Invention”.

Embodiments of the invention

The invention and its preferred developments are described in more detail below with reference to the drawings using preferred exemplary embodiments. Features that correspond to one another are provided with the same reference symbols in the figures.

• 1 Eine Druckmaschine mit einer erfindungsgemäßen Vorrichtung;
• 2 Eine erfindungsgemäße Vorrichtung und ein Diagramm;
• 3a-c Erfindungsgemäße Lösungen mit Spiegeln;
• 4a-c Strahlverläufe;
• 5a-c LED-Strahler ohne und mit Neigung;
• 6a-b Module einer erfindungsgemäßen Vorrichtung; und
• 7 Module einer erfindungsgemäßen Vorrichtung.

The drawings show:

• 1 A printing press with a device according to the invention;
• 2 A device according to the invention and a diagram;
• 3a-c Solutions according to the invention with mirrors;
• 4a-c Ray traces;
• 5a-c LED spotlights with and without inclination;
• 6a-b Modules of a device according to the invention; and
• 7th Modules of a device according to the invention.

1 shows schematically an exemplary printing press 1 for printing on a substrate 2 , e.g. paper, cardboard or plastic film (in sheet or web form), in plan view. It can be an offset and / or an inkjet printing machine. The printing press includes a feeder 3rd , at least one work 4th for applying a fluid 9 on the substrate and a work 5 for irradiating the (applied) fluid 9 . The fluid 9 can, for example, be a printing ink, in particular a UV-curable printing ink, or a printing varnish or, for example, an ink, in particular a UV-curable ink. The work 5 can be one or more devices according to the invention 6th for irradiating the fluid. Alternatively or in addition, one or more devices 6th also at other positions on the printing machine 1 be arranged, for example in a boom 7th .

In 1 are for example two different substrates 2 shown: a substrate 2 of large format (large width towards 41 ) and a substrate 2 of small format (small width in direction 41 ). Other formats are also possible, for example intermediate formats. During the operation of the printing press 1 however, there is only one format. On the substrate 2 is in a printed area 8th the applied fluid 9 shown.

The printing press 1 preferably comprises a transport device 50 , for example designed as a drum or belt, for transporting the printing material 2 in one transport direction 40 along the device according to the invention 6th .

The top view of the 1 additionally shows the modules described below 10 . The detailed view of a module in 1 shows this module (solely for reasons of better visibility), however, not from the top, but from below. In 2 (there: in the upper area) this is clearly visible.

In the 1 illustrated device 6th comprises several modules 10 for the generation of radiation, preferably UV radiation (alternatively, for example, IR radiation), in order to thereby the fluid 9 on the substrate 2 to treat, in particular to harden, polymerize and / or dry. The modules can have essentially the same (external) dimensions. The modules are in a row 11 arranged. The row is preferably substantially lateral to one direction 40 of the printing material transport arranged. In the row, the modules can be arranged adjacent to one another, in particular directly adjacent to one another. The modules can, however, also be spaced apart from one another and / or can be in the direction of 40 be arranged offset from one another in the row. In the 102 format, for example 25th Modules may be provided.

One module 12th (in the 1 : left) forms the beginning 11a the series 11 , another module 12th (in the 1 : right) forms the end 11b the series 11 ; the two modules are here called edge modules 12th designated. In between form modules 13th the inner 11c the series 11 ; these are here called inner modules 13th designated. The edge modules can also be two, three or four modules (on each side) and the inner modules can be correspondingly fewer. In 1 is only one module for the sake of clarity 10 (the edge module 12th shown in detail at the beginning of the series fc); The other modules also have such details (not shown) - possible differences are discussed below.

In the 1 illustrated printing machine 1 preferably comprises a digital computer 18th . This controls the device according to the invention 6th or their modules 10 , preferably by energizing the respective modules.

The module shown in detail as an example 10 (and also the other modules in the series 11 ) includes LED spotlights 14th , which are preferably designed as chips or LED emitter chips. The spotlights 14th are in a field 15th (English "array") or arranged in a 2D arrangement, preferably on a rectangular or square grid. Such a field 15th can on a substrate 16 be arranged and the substrate can be on a heat sink 17th be arranged. The module 10 can, for example, four substrates 16 (two by two arrangement) include.

2 shows the device according to the invention in the upper area 6th out 1 of the page; again is the (left) boundary module 12th exemplary more detailed than the other modules 10 shown. It can be clearly seen that the modules 10 radiation 26th submit. This radiation is generated by the individual LED spotlights 14th of the respective module generated, and in particular forms a respective radiation cone 26b . This meets the printing material 2 and especially on the printed area 8th and the fluid 9 . It can also be clearly seen that the radiation cone 26b neighboring modules 10 partly in an overlapping area 26c overlap. The overlap area can also be formed by more than two radiation cones. The overlap is preferably chosen such that the intensity of the radiation inside 11c the row reaches a predetermined homogeneity. Selectable parameters here are: opening angle of the radiation cone, extent of the field 15th in the direction 40 .

In the lower area of the 2 is a graph with measurement curves 30th shown. The diagram shows the optical power (in%) over the width (in centimeters) in the axial direction or over the number of modules 10 applied. A curve 30a (solid line) shows the (axial) course of the optical power with low homogeneity. The curve clearly shows a so-called drop-off on the left and right in the area of the format margins 31 on. This is due to the fact that the overlap 26c there is less (because axially outside the edge modules 12th no further modules are located).

Another curve 30a (dashed line) shows the course of the optical power when the modules are "dimmed", ie their current supply is reduced (eg by about 25%). It happens that machine operators dim the modules in order to save energy and costs. Due to the edge waste that is present, it can happen that the optical performance in the area of the edge waste is too low for adequate treatment of the printing material 2 (Drying, hardening). However, this is often not noticed by the operator, as this is the result of the Treatment mostly only in the central area of the arch 2 checks.

To prevent this from happening, not all modules 10 dimmed, only the inner modules 13th . The curve 30b (dash-dotted line) shows the course of the optical power with advantageous dimming (e.g. by around 25%) with compensation of the edge drop: it can be seen that the curve has a high degree of homogeneity of the optical power and that in particular there is no longer any significant edge drop. The transition from curve 30a to curve 30b (dashed) can not only be done by dimming, but also (or additionally) by so-called degradation, ie by operational aging of the modules 10 or their LED spotlights 14th .

In 2 it is also shown that there is a decrease in optical performance in the central area due to degradation 32 can come because the modules located there 10 are in operation for all formats, including the small formats. This can be taken into account when compensating or when dimming with compensation so that there is always an optimal curve 30b (dash-dotted) is reached.

The 3a , 3b and 3c show solutions according to the invention with mirrors. According to 3a is the edge module on three of its sides 19th with one mirror each 20th equipped. On the side of the inner module 13th on the other hand, no mirror is provided. The mirrors can, as in 3b recognizable to one level 21 of the module can be inclined, ie they can be inclined mirrors 20a be. The angle of inclination α is in 3b and 3c recognizable and can be in the range [Note: please specify range numbers here]. The mirrors can also be around an axis 22nd perpendicular to the plane 21 at an angle β be rotated. The angle β can be in the range [please specify range numbers here]. The mirrors in the 3a to 3c increase the yield of radiation from the edge module 12th which on the fluid 9 meets against at least one inner module 13th .

4a shows that a proportion of the radiation from an LED chip 14th hits a side wall and not the substrate 2 arrives (optical loss).

4b shows that a flat mirror 20th on the side of the module 12th or its chip 14th reduces optical loss.

4c shows that the mirror 20th may have a curvature or that it is a curved mirror 20b acts. This allows the optical losses to be reduced further.

In all three embodiments of the 4a to 4c each mirror can also consist of a plurality of individual mirrors 23 be educated. 3c shows such individual mirrors arranged adjacent to one another 23 .

5a shows an LED spotlight 14th or chip without primary optics; 5b an LED spotlight 14th or chip with primary optics 24 for bundling the rays or for shaping the jet cone 26a of the radiator. In 5c it is shown that the radiator or chip 14th of the edge module 12th including the primary optics 24 can be arranged inclined. The yield of the radiation from the edge module 12th which on the fluid 9 meets against at least one inner module 13th is thereby increased.

In 6a are modules 10 a device 6th shown in a first configuration, with an edge module 12th a field 15a with high packing density (of LED chips 14th ) and inner modules 13th one field each 15b with low packing density. The high packing density can be in the range [here please specify the range] and the low packing density in the range [please specify the range here]. For example, the high packing density can be twice the low packing density.

In 6b are the modules 10 shown in a second configuration. Here, too, the packing density is higher at the edge than inside.

In 7th are modules 10 a device 6th shown, the packing density of the LED chips 14th of the individual modules is the same. In this embodiment, instead, is the field 15c a box with LED chips 14th a high internal class and the field 15d a field with a low binning class. The embodiments of the 6th and 7th can also be combined, ie packing densities and binning classes can be used between the edge modules 12th and the inner modules 13th vary.

List of reference symbols

1

Printing press

2

Substrate

3

Feeder for printing material

4th

Plant for applying the fluid

5

Plant for irradiating

6th

Device for irradiating

7th

Outrigger for printing material

8th

Printed area

9

Fluid

10

Modules for generating radiation

11

line

11a

Beginning of the series

11b

End of row

11c

Interior of the series

12th

Edge modules

13th

inner modules

14th

LED spotlights / LED spotlight chips

15th

Field of LED spotlights

15a

High packing density field

15b

Field of low packing density

15c

Field with high binning class

15d

Field with a low binning class

16

Substrates

17th

Heat sink

18th

calculator

19th

Sides of the edge module

20th

mirror

20a

inclined mirror

20b

curved mirror

21st

Level of the module

22nd

Axis perpendicular to the plane of the module

23

Single mirror

24

Primary optics

25th

Secondary optics

26th

radiation

26a

Beam cone of an LED spotlight

26b

Beam cone of an array of LED spotlights

26c

Overlap of several jet cones

30th

Curves

30a

Curve of low homogeneity

30b

High homogeneity curve

31

Edge waste

32

central degradation

40

Direction of substrate transport

41

Transverse direction

50

Transport device

α, β

angle

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102004020454 A1 [0008]
• DE 102007058957 A1 [0009]
• US 2004/0080938 A1 [0010]
• US 2011/0175533 A1 [0011]

Claims (11)

Device for irradiating a fluid on a printing material, with modules (10) arranged essentially in a row (11) for generating radiation, comprising at least one edge module (12) each at the beginning or at the end of the row and a plurality of inner modules (13) inside the row, the modules each comprising at least one LED emitter (14) or LED emitters designed as a UV LED emitter (14), characterized in that the edge modules (12) one of the inner modules (13) have such a different structure that the yield of radiation from the edge modules, which the fluid (9) strikes, is increased compared to at least one inner module. Device according to Claim 1 , characterized in that the modules (10) each comprise i * j substrates (16) or i * j substrates (16) with respective heat sinks (17) and that each substrate comprises at least one LED emitter chip (14), wherein i and j ∈ ℕ \ {0}. Device according to Claim 1 or 2 , characterized in that the modules (10) or the substrates (16) each comprise an n * m field (15) of LED emitter chips (14), where n and m ∈ ℕ \ {0}. Device according to one of the preceding claims, characterized in that the radiation power of each module (10) can be controlled separately or can be controlled separately via the current supply. Device according to one of the preceding Claims 1 to 4th , characterized in that the edge module (12) on one of its sides (19) or on two of its sides (19) or on three of its sides (19), the side / sides not adjoining an inner module (13) , in each case a mirror (20) or in each case a mirror (20a) inclined to the plane (21) of the module (12) or in each case a mirror (20a) inclined to the plane of the module and rotated about an axis (22) perpendicular to the plane, or in each case comprises a curved mirror (20b). Device according to Claim 5 , characterized in that the mirror (20) is formed by a plurality of individual mirrors (23). Device according to one of the preceding Claims 1 to 4th , characterized in that at least one LED emitter (14) or at least one LED emitter with primary optics (24) is inclined to the plane (21) of the module (10) or inclined several times. Device according to one of the preceding Claims 1 to 7th , characterized in that the modules (10) each comprise several LED emitters (14) and that the packing density (15a) of the LED emitters on the edge module (12) compared to the packing density (15b) of the LED emitters on at least one inner Module (13) is increased or the packing density (15b) of the LED emitters (14) on at least one inner module (13) compared to the packing density (15a) of the LED emitters on the edge module (12) is reduced. Device according to one of the preceding Claims 1 to 8th , characterized in that the modules (10) each comprise several LED emitters (14) and that a number of the LED emitters of the edge module (12) from a binning class (15c) with a higher yield of radiation compared to at least one inner module (13) is selected or a number of the LED emitters of at least one inner module (13) is selected from a binning class (15d) with a lower yield of radiation compared to the edge module (12). Device according to one of the preceding Claims 1 to 9 , characterized in that the device (6) comprises an element (50) or a drum (50) or a belt (50) for moving the printing material (2) in a transport direction (40) and that the modules (10) in the Row (11) are arranged in the lateral direction (41) with respect to the transport direction. Device for irradiating a fluid on a printing material, with modules (10) arranged essentially in a row (11) for generating radiation, comprising at least one edge module (12) each at the beginning or at the end of the row and a plurality of inner modules (13) inside the row, the modules (10) each comprising at least one LED emitter (14) or LED emitters designed as a UV LED emitter (14), characterized in that the edge modules (12) compared to the inner Modules (13) are controlled and / or energized differently in such a way that the yield of radiation from the edge modules which the fluid (9) strikes is increased compared to at least one inner module.

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