The disclosure relates to a printer dryer device for drying printing substances on a printing medium, such as a printer dryer for drying an ink of an inkjet printer.
In print operations, liquid printing substances, such as inks, fixers, primers and coatings may be applied to a printing medium. The printing medium may then be dried, for example using hot air convection, infrared radiation dryers, or ultraviolet (UV) radiation dryers, or a combination of such drying techniques.
Ultraviolet curable inks may comprise polymers, oligomers, and photo initiators that are crosslinked in response to ultraviolet irradiation. Even though no significant evaporation takes place in the course of the UV irradiation and crosslinking, it is common to use the term “drying” when referring to the crosslinking of UV curable inks. These inks are very versatile, and can be printed on a large range of printing media, from paper and cardboard to plastics and even glass and ceramics.
A second type of inks are water-based inks, which are mainly used for printing on cardboard or paper. These prints can be made food-compliant, and hence can be employed to print on packages of food or beverages. Water-based inks may be dried by means of evaporation drying, such as by a combination of hot air convection and infrared or ultraviolet irradiation. They usually involve larger drying energy and/or drying times than UV curable inks.
Examples will now be described with reference to the accompanying drawings, in which:
Examples of the invention as described in the disclosure with reference to the figures may allow to reduce the total voltage drop across the light-emitting elements in a series connection of the printer dryer device, by arranging the light-emitting elements in a plurality of drying units across a medium transport direction of the printer. The drying unit may be staggered along the medium transport direction to allow the printer dryer device to dry a printing substance across an extended length along the medium transport direction.
The first drying unit 121 comprises a plurality of n ultraviolet (UV) light-emitting diodes (LED) L11, . . . , Ln1 electrically connected in series and geometrically arranged along a row in the medium transport direction x. Each of the UV LEDs L11, . . . , Ln1 is adapted to emit ultraviolet irradiation, such as at a wavelength of 395 nm, to dry a printing substance on a printing medium that passes by the printer dryer device along the medium transport direction x. For instance, the UV LEDs L11, . . . , Ln1 may dry a water-based ink by means of evaporation drying, or may cure an ultraviolet curable ink.
The second drying unit 12′1 generally corresponds in technical design and functionality to the first drying unit 121, and comprises a plurality of ultraviolet light-emitting diodes L′11, . . . , L′n1 connected in series in a row along the medium transport direction x. In the example of
As can be further taken from
The first input line 161, the plurality of light-emitting elements L11, . . . , Ln1 arranged in this order on the substrate 14 along the medium transport direction x, and the first output line 181 together with the voltage supply Vcc and the driver unit 20 together establish a driving circuit for the first drying unit 121. Given that the light-emitting elements L11, . . . , Ln1 are connected in series in the first drying unit 121, the total voltage drop along the first drying unit 121 corresponds to the sum of the voltage drops at each of the respective light-emitting diodes L11, . . . , Ln1. For instance, if the operating voltage drop at each light-emitting diode L11, . . . , Ln1 amounts to 3.5 V, the total voltage drop across the first drying unit 121 amounts to n×3.5 V.
The second drying unit 12′1 downstream from the first drying unit 121 in the medium transport direction x is generally similar to the first drying unit 121. A second input line 16′1 connects the first UV LED L′11 in the series of light-emitting elements of the second drying unit 12′1 to the voltage source Vcc, and a second output line 18′1 connects the last light-emitting element L′n1 at the opposite end of the second drying unit 12′1 to the common driver unit 20. Hence, the first drying unit 121 and the second drying unit 12′1 are electrically connected in parallel between the voltage source Vcc and the driver unit 20.
In the configuration of
In an example, the UV LEDs may be spaced at a spacing of 2.5 mm each along the medium transport direction x. Assuming a voltage drop of 3.5 V at each UV LED and a driver unit 20 that can safely handle operating voltages up to 80 V, each of the first and second drying units 121, unit 12′1 may comprise
UV LEDs. This allows for an effective drying length per drying unit of
n×2.5 mm=22×2.5 mm=55 mm, (2)
and hence a total drying length of 2×55 mm=110 mm along the medium transport direction x.
In the configuration of
In other examples, some of the light emitting diodes L11, . . . , Ln1 , L′11, . . . , L′n1 may be arranged slightly off-center, for instance within a range of ±20% of a lateral extension of the first or second drying unit (along the transverse direction).
The transverse direction y (orthogonal to the medium transport direction x) corresponds to a width direction of the printer dryer device. Along the transverse direction y, a (possibly large) number k of further first drying units 122, . . . , 12k and second drying units 12′2, . . . , 12′k may be arranged on the substrate 14. Each of the pairs of first drying units 122, . . . , 12k and second drying units 12′2, . . . , 12′k may correspond in design and functionality to the first drying unit 121 and the second drying unit 12′1, respectively, and may each be connected in parallel to the voltage source Vcc and driver unit 20 in the same way as the first drying unit 121 and the second drying unit 12′1 respectively.
Assuming a pitch of 2.5 mm between neighboring drying units and a total width of the drying unit 10 of 1300 mm,
strings of pairs of first drying units 121, . . . , 12k and second drying units 12′1, . . . , 12′k can be arranged and electrically connected in parallel along the transverse direction y between the voltage source Vcc and the driver unit 20.
Other printers can reach even wider sizes of up to 2100 mm or beyond, and hence a correspondingly higher number k of pairs of first and second drying units across the transverse direction y can be provided.
The configuration allows for a quick and efficient drying of printing substances on a printing medium, in particular for fast evaporation drying of water-based inks.
In the configuration of
The substrate 14 may comprise a printed circuit board 22, and the first drying units 121, . . . , 12k and the second drying units 12′1, . . . , 12′k first input lines 161, . . . , 16k, second input lines 16′1, . . . , 16′k, first output lines 181, . . . , 18k, and second output lines 18′1, . . . , 18′k may be formed on the printed circuit board 22 using “chip on board” (COB) technology.
The printed circuit board 22 may be connected via an adhesive layer 24 to a cooling layer 26. For instance, the cooling layer 26 may be an aluminum layer with a plurality of p pipes 281, . . . , 28p through which a cooling fluid, such as water, circulates. The cooling layer 28 cools the energy-emitting elements of the first drying units 121, . . . , 12k and second drying units 12′1, . . . , 12′k. At the same time, the cooling layer 26 cools the input lines 161, . . . , 16k, 16′1, . . . , 16′k and output lines 181, . . . , 18k, 18′1, . . . , 18′k, which allows the supply lines to be placed in close spatial proximity to the drying units without the risk of overheating.
As further illustrated in
In the configuration of
In the configuration of
The examples described previously with reference to
As can be further taken from
Assuming again a pitch of 2.5 mm between neighboring light-emitting diodes in the medium transport direction x, an operating voltage of 3.5 V for each light-emitting diode, and a maximum operational voltage of 80 V, the total drying length along the medium transport direction x can be extended to 3×55 mm=165 mm.
In a block S10, the printing medium is irradiated by means of a first plurality of energy-emitting elements, wherein the first plurality of energy-emitting elements are electrically connected in series.
In a block S12, the printing medium is irradiated by means of a second plurality of energy-emitting elements downstream of the first plurality of energy-emitting elements in the medium transport direction of the printing medium, and the second plurality of energy-emitting elements are electrically connected in series.
At least one energy-emitting element among the second plurality of energy-emitting elements is not electrically connected in series to an energy-emitting element among the first plurality of energy-emitting elements.
A printer dryer device according to an example comprises a first drying unit, wherein the first drying unit comprises a first plurality of energy-emitting elements to dry a printing substance on a printing medium, wherein the first plurality of energy-emitting elements are electrically connected in series in the first drying unit. The printer dryer device further comprises a second drying unit, wherein the second drying unit comprises a second plurality of energy-emitting elements to dry the printing substance on the printing medium, wherein the second drying unit is arranged downstream from the first drying unit in a medium transport direction of the printing medium. The second plurality of energy-emitting elements are electrically connected in series in the second drying unit, wherein at least one energy-emitting element among the second plurality of energy-emitting elements is not electrically connected in series to an energy-emitting element among the first plurality of energy-emitting elements.
The printing medium may be any medium suitable to be printed, including paper, cardboard, plastic, glass, or ceramics.
In an example, the second drying unit may be aligned with the first drying unit alongside the medium transport direction of the printing medium.
In another example, the first plurality of energy-emitting elements may be arranged along a first lengthwise direction along the medium transport direction, wherein the second plurality of energy-emitting elements may be arranged along a second lengthwise direction along the medium transport direction, wherein the second lengthwise direction may be parallel to the first lengthwise direction and/or wherein the second lengthwise direction may be aligned with the first lengthwise direction.
An alignment of the first and second lengthwise directions may refer to an alignment in a transverse direction, i.e., in a direction orthogonal to the medium transport direction.
In an example, the second lengthwise direction may coincide with the first lengthwise direction.
In another example, the second lengthwise direction may differ from the first lengthwise direction in a transverse or orthogonal direction by less than 20% of a lateral extension of the second drying unit, and in particular by less than 10%.
A lateral extension of the second drying unit may refer to a spatial extension of the second drying unit in a transverse direction, i.e., in a direction perpendicular to the medium transport direction.
In an example, none of the energy-emitting elements in the second plurality of energy-emitting elements is electrically connected in series to any of the energy-emitting elements in the first plurality of energy-emitting elements.
In an example, the first drying unit and the second drying unit may be electrically independent and uncoupled.
In an example, the first dying unit and the second drying unit may be electrically connected in parallel, in particular connected in parallel between a common voltage source and a driver unit.
This may allow to reduce the total voltage drop across the plurality of energy-emitting elements in the series connections of the first and second drying units. At the same time, the printer dryer device may dry the printing substance across an extended length along the medium transport direction, corresponding to the combined length of the first and second drying units.
The printer dryer device may further comprise a substrate on which the first drying unit and the second drying unit are formed, wherein the substrate may be a cooled substrate, in particular a fluid-cooled substrate.
A cooling fluid for cooling the substrate may be a gas or a liquid, and may in particular comprise water.
In an example, the substrate comprises a printed circuit board.
The first plurality of energy-emitting elements and the second plurality of energy-emitting elements as well as wiring and voltage supply for the first drying unit and the second drying unit may be printed on the printed circuit board using semiconductor fabrication techniques.
In an example, the printer dryer device comprises a first set of supply lines electrically supplying the first drying unit, and a second set of supply lines electrically supplying the second drying unit. The second set of supply lines may be different from the first set of supply lines.
The first and second sets of supply lines may be formed on the cooled substrate, and may be cooled by means of the cooling fluid.
In an example, the first set of supply lines comprises a first input line and a first output line, wherein the first input line is connected to a first energy-emitting element at a first end of the first plurality of energy-emitting elements connected in series, and the first output line is connected to a second energy-emitting element at a second end of the first plurality of energy-emitting elements connected in series, wherein the second end is opposite from the first end.
The second set of supply lines may comprise a second input line and a second output line, wherein the second input line is connected to a first energy-emitting element at a first end of the second plurality of energy-emitting elements connected in series, and the second output line is connected to a second energy-emitting element at a second end of the second plurality of energy-emitting elements connected in series, wherein the second end is opposite from the first end.
The second output line may be different from the first output line, and in particular electrically non-connected to the first output line. The second input line may be different from the first input line, and in particular electrically non-connected to the first input line.
The printing substance may be a printing fluid, in particular a printing ink.
In an example, the first plurality of energy-emitting elements are for drying the printing substance on the printing medium by evaporation drying; and/or the second plurality of energy-emitting elements are for drying the printing substance on the printing medium by means of evaporation drying.
The first plurality of energy-emitting elements may comprise light-emitting diodes (LEDs), and in particular ultraviolet light (UV) emitting diodes.
The second plurality of energy-emitting elements may likewise comprise light-emitting diodes (LEDs), and in particular ultraviolet light (UV) emitting diodes.
The first drying unit and/or the second drying unit may comprise at least 15 energy-emitting elements electrically connected in series, and in particular at least 20 energy-emitting elements electrically connected in series.
In an example, the first plurality of energy-emitting elements are arranged geometrically along a first row in the first drying unit. The first row may define the first lengthwise direction.
Similarly, the second plurality of energy-emitting elements may be arranged geometrically along a second row in the first drying unit. The second row may define the second lengthwise direction.
In an example, the first row and/or the second row each comprises at least 15 energy-emitting elements electrically connected in series, and in particular at least 20 energy-emitting elements electrically connected in series.
Examples of printer dryer devices may comprise more than two drying units arranged along the medium transport direction, such as three or four drying units.
Apart from their positioning in the printer dryer device, these further drying units may be similar or identical in technical design and functionality to the first and second drying units described above. Each further drying unit relates to its predecessor along the medium transport direction as the second drying unit described above relates to the first drying unit.
In an example, the printer dryer device comprises a third drying unit, wherein the third drying unit comprises a third plurality of energy-emitting elements to dry the printing substance on the printing medium; wherein the third drying unit is arranged downstream from the second drying unit in the medium transport direction of the printing medium. The third plurality of energy-emitting elements may be electrically connected in series in the third drying unit, wherein at least one energy-emitting element among the third plurality of energy-emitting elements is not electrically connected in series to an energy-emitting element among the first plurality of energy-emitting elements, nor among the second plurality of energy-emitting elements.
In an example, the third drying unit is aligned with the first drying unit and/or the second drying unit alongside the medium transport direction of the printing medium.
The third plurality of energy-emitting elements may be arranged along a third lengthwise direction along the medium transport direction, wherein the third lengthwise direction is parallel to the first lengthwise direction and/or the second lengthwise direction.
In an example, the third plurality of energy-emitting elements may be arranged along a third lengthwise direction along the medium transport direction, wherein the third lengthwise direction is aligned with the first lengthwise direction and/or with the second lengthwise direction.
The third lengthwise direction may coincide with the first lengthwise direction and/or with the second lengthwise direction.
In an example, the third lengthwise direction differs from the first lengthwise direction and/or from the second lengthwise direction by less than 20% of a lateral extension of the third drying unit, and in particular by less than 10%.
In an example, none of the energy-emitting elements in the third plurality of energy-emitting elements is electrically connected in series to any of the energy-emitting elements in the first plurality of energy-emitting elements nor in the second plurality of energy-emitting elements.
The disclosure further relates to a printing system for printing the printing substance on the printing medium moving along the medium transport direction, the printing system comprising a printer dryer device with some or all of the features described above.
The printing system may further comprise a distribution unit to distribute the printing substance on the printing medium, wherein the printer dryer device is located downstream from the distribution unit in the medium transport direction of the printing medium.
The disclosure further relates to a method for drying a printing substance on a printing medium, comprising irradiating the printing medium by means of a first plurality of energy-emitting elements, and irradiating the printing medium by means of a second plurality of energy-emitting elements downstream from the first plurality of energy-emitting elements in a medium transport direction of the printing medium, wherein the first plurality of energy-emitting elements are electrically connected in series, wherein the second plurality of energy-emitting elements are electrically connected in series, and wherein at least one energy-emitting element among the second plurality of energy-emitting elements is not electrically connected in series to an energy-emitting element among the first plurality of energy-emitting elements.
In an example, irradiating the printing medium by means of the first plurality of energy-emitting elements and/or by means of the second plurality of energy-emitting elements is evaporation drying.
In a further example, the method further comprises irradiating the printing medium by means of a third plurality of energy-emitting elements downstream from the second plurality of energy-emitting elements in the medium transport direction of the printing medium, wherein the third plurality of energy-emitting elements are electrically connected in series, and wherein at least one energy-emitting element among the third plurality of energy-emitting elements is not electrically connected in series to at least one energy-emitting element among the first plurality of energy-emitting elements nor among the second plurality of energy-emitting elements.
The description of the examples and the Figures merely serve to illustrate the disclosure, but should not be understood to imply any limitation. The scope of the disclosure is to be determined from the appended claims.
Number | Date | Country | Kind |
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17183369.2 | Jul 2017 | EP | regional |
Number | Date | Country | |
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Parent | 15994441 | May 2018 | US |
Child | 16404291 | US |