Patent Application
20240061341
The field of the invention relates to apparatus and methods for exposure of relief precursors, in particular printing plate precursors, and more in particular for front and backside exposure of printing plate precursors.
Relief structures can be made by transfer of image information onto an imageable layer and removing parts of the imageable layer. The formed relief may then be used to transfer the information in a printing step onto a substrate. An example of a relief precursor is a printing plate precursor. Digitally imageable flexible printing plate precursors are known, and typically comprise at least a dimensionally stable support layer, a photosensitive layer and a digitally imageable mask layer. The digitally imageable mask layer may be e.g. a laser-ablatable layer. In case of conventional printing plate precursors, the digitally imageable layer is replaced by a separate mask which is attached to a photosensitive layer.
To produce a printing plate from a printing plate relief precursor, according to existing methods, first a mask is written into the digitally imageable layer based on image data to be printed. Following the writing of the mask, the plate is exposed through the mask with radiation such that the photosensitive layer undergoes polymerization or crosslinking or a reaction changing the solubility or fluidity of the photosensitive layer in the regions which are not covered by the mask. Following the exposure, the residues of the mask and of the non-exposed portions of the photosensitive layer are removed. This may be done with one or more liquids in a washer apparatus or by thermal development wherein non-exposed material of the photosensitive layer is liquefied by temperature increase and removed.
Exposure apparatus for printing plate precursors are known. An exposure apparatus may comprise a first light source for back exposure and a second light source for front exposure. Back exposure may be done using a set of UV light tubes or a LED array. The back exposure creates a solid layer (floor) onto which the relief structures are generated. Front exposure may be done using a movable UV light source, such as a movable laser or a LED bar or using stationary light source e.g. an arrangement of tubular light sources. Some exposure apparatus only do front exposure or only do back exposure, depending on the requirements. In some cases the exposure apparatus is capable to expose from both sides and embodiments of the invention relate to such cases.
The object of embodiments of the invention is to provide apparatus and methods to expose a relief precursor according to a sequence increasing the productivity, whilst maintaining good results.
According to a first aspect of the invention, a method for exposing a relief precursor is provided, using a first light source configured to expose a first side of a relief precursor during a first exposure period of a first exposure step and a movable second light source configured to expose a second side of the relief precursor opposite the first side during one or more second exposure periods of one or more second exposure steps. The method comprises the steps of receiving through an operator interface at least one first characteristic representative for the first exposure period and/or at least one second characteristic representative for the one or more second exposure periods, determining a sequence of operation for the first light source and the second light source based on the at least one first and/or second characteristic, and exposing the relief precursor according to the determined sequence. The sequence is such that each of the one or more second exposure periods either fully overlaps with the first exposure period or does not overlap with the first exposure period.
In this way an appropriate sequence can be determined based on characteristics entered by an operator. The sequence is determined so that it is avoided that the first light source changes from an exposing state into a non-exposing state whilst the second light source is in an exposing state. In addition, the sequence may include a simultaneous exposure with the first and second light source as long as the second exposure period fully overlaps (i.e. is fully within) the first exposure period. By introducing such a determining step to determine a suitable sequence, the productivity can be increased. Indeed, by introducing overlap where possible without causing a negative impact on the quality of the results, the time needed to perform the method may be shorter.
In a preferred embodiment, the first light source is a back light source for creating a solid layer (floor) at the first side (the back side) of the relief precursor while the second light source is a front light source generating relief structures at the second side (the front side) of the relief precursor.
Thus, according to embodiments of the invention, a front exposure period will always fully overlap with the back exposure period or not at all. In this manner, the thermal behavior of the relief precursor P is controlled during any front exposure (e.g. same front and back exposure conditions during the whole front exposure), ensuring thus the quality of the printing plate, while an overlap—where possible—enables the reduction of the total duration of the exposure method, increasing thus the productivity of the method.
Preferably, both the first and the second characteristics can be changed by an operator and received through the operator interface. In this way, first exposure and second exposure may be customized at will. Alternatively one of the first or second characteristics is preset and the other one is variable and received through the operator interface. In this way, a predetermined number of scenarios may be provided to help the user prior to customization. It is noted that the first and the second characteristics may contain indications for both the first and second exposure period and a first and second non-exposure period of a first and second exposure step, respectively. However, typically first and second non-exposure times will be preprogrammed and not entered by an operator. Also, the first and/or second non-exposure time may be zero or negligible. Alternatively, only the full time period of the first and second exposure step may be provided if the non-exposure period is preprogrammed or negligible.
According to a preferred embodiment, the step of determining a sequence comprises, if the first exposure period is shorter than any one of the second exposure periods of the one or more second exposure steps, selecting a sequential sequence to operate only the first light source or only the second light source at a time. In this way, if the first exposure period is shorter than any second exposure period, an overlap is avoided to prevent first exposure during only part of a second exposure step. In this manner the exposure conditions, e.g. the temperature conditions will be substantially uniform, ensuring in turn a qualitatively good and substantially uniform second exposure step. According to a first option, the first exposure period may precede the at least one second exposure period and according to a second option the first exposure period may follow after the at least one second exposure period. If more than one second exposure step is performed, even more options are possible. Depending on circumstances, one of the three options may be preferred, and the step of determining may optionally take into account further considerations, such as the type of relief precursor, the intensity used, etc. in order to further improve the suitability of the sequence.
According to a preferred embodiment, the step of determining a sequence comprises, if the first exposure period is longer than one of the second exposure periods, selecting that second exposure period for overlapping with the first exposure period. In this way if the first exposure is longer than a second exposure period, second and first exposure may be performed together during that second exposure period, reducing thus the total duration of exposure. According to a first option, the first and second exposure periods may then start together. For some applications, a higher quality is achieved by performing the second exposure as early as possible. For example, the amount of available oxygen may play a role for the second exposure and by doing the second exposure early less oxygen may be present in the relief precursor. Alternatively the first and second exposure periods may end together or the second exposure step selected for overlap may be enclosed in the middle of the first exposure step. Depending on circumstances, one of the three options may be preferred, and the step of determining may optionally take into account further considerations, such as the type of relief precursor, the intensity used, etc in order to further improve the sequence for a desired result.
According to a preferred embodiment, the step of determining a sequence comprises determining for at least one of said one or more second exposure steps whether the second exposure period thereof is smaller than the first exposure period; and if yes, determining the sequence such that the second exposure period of said one second exposure step fully overlaps with the first exposure period; and if no, determining the sequence such that the second exposure period of said one second exposure step does not overlap with the first exposure period. Thus, the step of determining a sequence typically comprises comparing the first exposure period and the one or more second exposure periods of the one or more second exposure steps. In this way, the sequence may be determined simply by comparing directly the durations of the first exposure period and each second exposure period to determine the best sequence for the second and first light sources.
For example, when the one or more second exposure steps comprise a single second exposure step the step of determining a sequence comprises two steps. In a first step the first and second exposure period are compared. In a second step it is determined that the second exposure step is performed such that the second exposure period of said second exposure step fully overlaps with the first exposure period, if the second exposure period is smaller than the first exposure period, or that the second exposure step is performed such that the second exposure period of said second exposure step does not overlap with the first exposure period, if the second exposure period is larger than the first exposure period.
According to a preferred embodiment, during the first exposure period a light intensity emitted by the first light source is substantially constant. In this way the first exposure is performed with a constant intensity, ensuring over time substantially uniform conditions on the relief precursor during the at least one second exposure step.
When referring to a light intensity emitted by the first light source, it is intended to refer to an intensity measured by an Ophir 10A-V1.1 sensor with a 16 mm diameter diaphragm (Ophir Optronics Solutions Ltd) arranged so that the measuring side of the sensor in located in a plane corresponding with the first side of a relief precursor when the relief precursor is arranged in the exposure apparatus. Thus, when the exposure apparatus has a carrying structure with a support surface, e.g. a glass plate with a support surface, the sensor can be placed on the support surface with its measuring side oriented towards the first light source. This is illustrated in
According to a preferred embodiment, the at least one first characteristic comprises a characteristic representative for the duration of the first exposure period. In this way the duration of the first exposure period can be taken into account when determining the sequence of operation for the second and first light sources. For example, the at least one first characteristic comprises any one of the following or a combination thereof: a duration of the first exposure period, a duration of a first non-exposure period of the first exposure step, a value representative for a light intensity used during the first exposure period. In this way, the conditions of exposure during the first exposure step can be taken into account when determining the sequence of operation for the second and first light sources. It is further noted that a value representative of a light intensity during the first exposure may be correlated to the duration of the first exposure period insofar as both influence a light dose received during the first exposure period. In an example, the first source is a set of UV light tubes provided with a shutter and the non-exposure period may correspond with a time for preconditioning the first light source. In some examples, where an operator enters a value representative for the first exposure period, during the determining it may be determined to increase or decrease the entered first exposure period based on calibration parameters and/or exposure conditions, e.g. based on whether or not a shadow plate is used, see further.
According to a preferred embodiment, the at least one second characteristic comprises at least one characteristic representative for the duration of the one or more second exposure periods. In this way the duration of the one or more second exposure periods can be taken into account when determining the sequence of operation for the second and first light sources. For example, the at least one second characteristic comprises any one of the following or a combination thereof: a speed value for the speed of the movement of the second light source during the one or more second exposure steps, a number of times the same second exposure step is repeated, a duration of a second exposure period of said one or more exposure periods, a duration of a non-exposure period of a second exposure step of said one or more second exposure steps, a value representative for a light intensity used during a second exposure period of the one or more second exposure periods. In particular the speed at which the second light source moves during a second exposure period influences the duration of that second exposure period for a given relief precursor having a given size and can be taken into account for determining the sequence of operation for the second and first light sources. Additionally the number of times the same second exposure step is repeated influences the total duration of the at least one second exposure step and can be taken into account for determining the sequence of operation for the second and first light sources. It is further noted that a value representative of a light intensity may be correlated to a speed value for the movement of the second light source insofar as both influence a light dose received during a second exposure period. Thus, an operator could enter only an intensity value and/or a dose, and a suitable speed (and hence second exposure time) can be determined based thereon by a control means.
When referring to a light intensity emitted by the second light source, it is intended to refer to an intensity between the second light source and a plane corresponding with the first side of a relief precursor when the relief precursor is arranged in the exposure apparatus, at a distance of 15 mm from said plane. Thus, when the exposure apparatus comprises a carrying structure with a support surface, e.g. a glass plate, the intensity is the intensity at a distance of 15 mm above the support surface. However, because the sensor has a certain height and the distance between the second light source and the support surface is typically quite small, the light intensity may have to be measured outside of the exposure apparatus. Thus, the sensor may be arranged outside of the exposure apparatus, but such that the measuring side of the sensor is at a distance dm of the second light source which corresponds with a distance d2 between the second light source and the support surface minus 15 mm (dm=d2-15 mm) Also the intensity of the second light source may be measured by an Ophir 10A-V1.1 sensor with a 16 mm diameter diaphragm (Ophir Optronics Solutions Ltd). This is illustrated in
Note that the distance is measured here between the second light source and the support side of the sensor, and not between the second light source and the measuring side of the sensor. This is illustrated in
Preferably, the receiving comprises receiving the first exposure period and, for each different second exposure step, a combination of the speed of the movement of the second light source and a number of times the second exposure step is repeated. The one or more second exposure periods may then be derived from the one or more received speed values and corresponding repeat numbers.
According to a preferred embodiment, each second exposure step comprises a second non-exposure period following the second exposure period, and the step of determining takes into account the second non-exposure period. In this way, delays inherent to the exposure process can be taken into account in an exposure step. For instance during the second non-exposure period, time can be provided for moving the second light source first into its initial position after an exposure period.
According to a preferred embodiment, the step of determining is such that the time needed to perform the first exposure step and the one or more second exposure steps is shorter than the time needed to perform the first exposure step and the one or more second exposure steps sequentially.
According to a preferred embodiment, each second exposure step comprises a forward movement and a backward movement. Preferably the second light source exposes the second side during the forward movement during the second exposure period, and the second light source does not expose the second side during the backward movement. In other words, a second exposure step consists of an exposure period corresponding to the forward movement, during which the second light source exposes the relief precursor, and a non-exposure period corresponding to the backward movement, during which the second light source is turned off and merely brought back into its initial position. Alternatively the second light source may expose the second side during both the forward movement and the backward movement, and a first second exposure step will correspond to the forward movement whilst a further second exposure step will correspond to the backward movement. In such an embodiment the non-exposure period during the first and further second exposure step will typically be negligible or very small.
According to a preferred embodiment, the one or more second exposure steps comprise at least two second exposure steps. In this way, a second exposure may be distributed over at least two second exposure steps. Preferably the at least two second exposure steps comprise two different second exposure steps and the step of receiving comprises receiving a second characteristic for each different second exposure step. In this way, the second side of the relief precursor may be exposed sequentially under different conditions, in particular according to a plurality of cycles with stepwise increased or decreased intensities and/or speeds to improve the quality of the edges of the relief structures. For example, one or more cycles with a first intensity and speed may be followed by one or more cycles with a different intensity and/or speed. Alternatively, the at least two exposure steps may be identical, to distribute exposure over time e.g. for thermal reasons (avoiding heat accumulating when exposing during a single cycle at a higher intensity and/or lower speed).
According to a preferred embodiment, the step of determining a sequence comprises the following steps:
According to a preferred embodiment, the step of receiving comprises presenting the operator with an operator interface allowing the operator to enter the at least one first and/or second characteristic. In this way, the sequence can be based on customized characteristics entered by an operator to increase the range of applications of the method.
According to a preferred embodiment, the method comprises prior to the step of determining, and optionally prior to the step of receiving, the step of receiving through the operator interface an operation mode out of one or more operation modes. The one or more operation modes comprise at least a first operation mode indicating that the determining step is to be performed to determine the sequence and a second operation mode indicating that a predetermined sequence is to be performed. In this way a user may choose between a predetermined sequence and a sequence calculated to improve the productivity. A predetermined sequence may be a sequence the user has used in the past or a pre-programmed sequence or a sequence entered by an operator.
According to a preferred embodiment, the second operation mode indicates that the one or more second exposure steps need to be performed before the first exposure step, and the one or more operation modes comprise a third operation mode indicating that the one or more second exposure steps need to be performed after the first exposure step. The third mode operation corresponds to a generally preferred mode of operation since an already exposed floor layer is regarded as generally a better basis for relief structures than a non-exposed one. In this way, more flexibility is offered to a user to adapt the exposure method to his needs depending on the circumstances.
According to a preferred embodiment, a movable shield is moved between the first light source and the relief precursor as the second light source is moved. Due to the presence of the moveable shield between the first light source and the relief precursor, the first side of the relief precursor receives less light than without the movable shield. Preferred features of the movable shield, also called shadow plate, can be found in patent application in the Netherlands with application number N2024756 filed on 24 Jan. 2020, which is included herein by reference. For such embodiments, the operator may enter a first exposure period which takes into account that the net dose received will be lower due to the shadow plate, or an operator may enter a value for the first exposure period which does not take into account that the net dose will be lower due to the shadow plate. In the latter case a corrected value for the first exposure period may be determined taking into account the loss due to the shadow plate, and this corrected value may be used for determining the sequence.
According to a preferred embodiment, the first exposure step is performed such that the intensity at the surface of the first side of the precursor, measured as specified above, is in the range of 1 to 200 mW/cm2, preferably 1 to 100 mW/cm2, more preferably in the range of 10 to 50 mW/Cm2; and/or such that a dose at the surface of the first side of the precursor is in the range of 0.01 to 30 J/cm2, preferably in the range of 0.1 to 30 J/cm2, more preferably in the range of 1 to 30 J/cm2.
According to a preferred embodiment, each second exposure step is performed such that the intensity emitted on the second side of the precursor and measured as specified above, is in the range of 20 to 2000 mW/cm2; preferably in the range of 40 to 1000 mW/cm2, more preferably in the range of 50 to 500 mW/cm2 and/or such that a dose at the surface of the second side of the precursor is in the range of 1 to 100 J/cm2, preferably in the range of. 2 to 80 J/cm2, more preferably in the range of 4 to 50 J/cm2.
According to a preferred embodiment, the relief precursor comprises at least a dimensionally stable support, a photoactive layer and optionally a further layer selected from the group comprising a barrier layer, a mask layer (integral or added), a slip layer, an adhesion layer, a protection layer, a functional layer and combinations thereof.
According to a preferred embodiment, the first light source, preferably a stationary light source, comprises a plurality of LEDs or a plurality of light tubes, or a plurality of laser diodes or combinations thereof. Optionally the first light source comprises an intensity control means configured for changing the intensity emitted by the first light source. For example, if the first light source is a LED array, the intensity control means may be a drive means configured to drive the LED array with different power levels. Alternatively, the intensity control means may be an optical means configured vary the light intensity on the relief precursor.
According to a preferred embodiment, the second light source comprises a plurality of LEDs. In this way, a variable intensity may be achieved, in particular for exposing the relief precursor in at least two steps with at least two different intensities. Optionally the second light source comprises an intensity control means configured for changing the intensity emitted by the second light source. For example, if the second light source is a LED array, the intensity control means may be a drive means configured to drive the LED array with different power levels. Alternatively, the intensity control means may be an optical means configured vary the light intensity on the relief precursor. Also, the intensity may be changed by selecting a plate with suitable optical characteristics amongst a plurality of plates with different optical characteristics, and arranging this plate between the second light source and the relief precursor to influence the intensity received by the relief precursor. This plate may be changed when a different intensity is required. In yet another example, a PCB with driver circuitry for generating a required drive current of the second light source may be selected amongst a plurality of PCBs configured for generating different drive current, depending on the required intensity. Also, the distance between the second light source and the relief precursor may be changed to influence the intensity received by the relief precursor. The same methods may be used to change the intensity of the first light source.
According to a preferred embodiment, the illuminated area from the first light source covers an area of 0.5 to 90% of the surface area of the precursor.
According to a preferred embodiment, additional steps are performed in advance to the exposure step comprising any one of the following: removing a protection layer, adding a mask layer, ablating a mask layer, pre-exposing the precursor, and combinations thereof; and/or additional steps are performed after the exposure step which are selected from the group comprising treatment with a liquid, treatment with a gas, thermal treatment, contacting with a surface, removal of material which may be dissolved or liquefied, exposure to electromagnetic radiation, exposure to a plasma, cutting, sanding or combinations thereof.
According to another aspect of the invention, a control means is provided for controlling a first light source configured to expose a first side of a relief precursor during a first exposure period of a first exposure step and a movable second light source configured to expose a second side of the relief precursor opposite the first side during one or more second exposure periods of one or more second exposure steps. The control means is configured to receive through an operator interface at least one first characteristic representative for the first exposure period and/or at least one second characteristic representative for the one or more second exposure periods. The control means is configured to determine a sequence of operation for the first light source and the second light source based on the at least one first and/or second characteristic. The sequence is such that each of the one or more second exposure periods either fully overlaps with the first exposure period or does not overlap with the first exposure period. The control means is configured to control the first and second light source in accordance with the determined sequence.
In this way, according to embodiments of the invention, a second exposure period will always fully overlap with the first exposure period or not at all. In this manner, the relief precursor is ensured to behave substantially uniformly during a second exposure step, ensuring thus the quality of the exposure, while an overlap—where possible—enables the reduction of the total duration of the first and second exposure steps, increasing thus the productivity achieved by the control means.
The control means may be further configured to perform any one or more of the method steps of embodiments of the method disclosed above.
According to a further aspect of the invention, there is provided a computer program comprising computer-executable instructions to perform the method, when the program is run on a computer, according to any one of the steps of any one of the embodiments disclosed above.
According to a further aspect of the invention, there is provided a computer device or other hardware device programmed to perform one or more steps of any one of the embodiments of the method disclosed above. According to another aspect there is provided a data storage device encoding a program in machine-readable and machine-executable form to perform one or more steps of any one of the embodiments of the method disclosed above.
According to a further aspect of the invention, there is provided an exposure apparatus comprising a first light source configured to expose a first side of a relief precursor during a first exposure period of a first exposure step, a movable second light source configured to expose a second side of the relief precursor opposite the first side during one or more second exposure periods (Te2) of one or more second exposure steps, a moving means configured to move the second light source, and a control means according to any one of the embodiments above or a control means storing the computer program of any one of the embodiments above, said control means being configured to control the first light source, the second light source and the moving means in accordance with the determined sequence.
Preferably, the relief precursor is a precursor for an element selected from the group comprising: a flexographic printing plate, a relief printing plate, a letter press plate, an intaglio plate, a (flexible) printed circuit board, an electronic element, a microfluidic element, a micro reactor, a phoretic cell, a photonic crystal and an optical element, a Fresnel lens. To obtain a microfluidic element or a micro reactor an additional layer is added on top of the formed relief, thereby creating channels and spaces.
The accompanying drawings are used to illustrate presently preferred non limiting exemplary embodiments of the apparatus and method of the present invention. The above and other advantages of the features and objects of the invention will become more apparent and the invention will be better understood from the following detailed description when read in conjunction with the accompanying drawings, in which:
The first light source 1 substantially extends in a plane parallel to the relief precursor P. The first light source 1 is stationary. The second light source 2 is movable back and forward as indicated with arrow A1, in a plane parallel to the plane of the first light source 1.
Preferably, the first light source 1 is configured to illuminate a first illumination area of a plane (having a width w1′ in
The carrying structure 3, e.g. a glass plate, is configured for supporting the relief precursor, and is located between the second light source 2 and the first light source 1. The carrying structure 3 may be transparent to electromagnetic radiation emitted from the first light source 1.
The first light source 1 may be selected from the group comprising: a plurality of LEDs, a set of fluorescent lamps, a flash lamp, a set of light tubes, an LCD screen, a light projection system (with movable mirrors), a sun light collection system, and combinations thereof. The second light source 2 may be selected from the group comprising an LED array, a set of fluorescent lamps, a flash lamp, a set of light tubes arranged in a linear fashion, a (scanning) laser, an LCD screen, a light projection system (with movable mirrors), and combinations thereof. In the example of
During a first exposure step S1, the first light source 1 may expose the relief precursor P during a first exposure period Te1 and may not expose the relief precursor P during a first non-exposure period Tne1. A first non-exposure period Tne1 may take into account delays inherent to the first exposure process. Typically, when the first source 1 is a set of UV light tubes provided with a shutter, a first non-exposure period Tne1 may comprise a time period for preconditioning the first light source.
During a second exposure step S2 or S2′, the second light source 2 may expose the relief precursor P during a second exposure period Te2 and may not expose the relief precursor P during a second non-exposure period Tne2. A second non-exposure period Tne2 may take into account delays inherent to the second exposure process. Typically the second light source 2 is moved in one direction during a second exposure period Te2 to expose the complete surface of the relief precursor, and moved in the opposite direction, back into its original position, during a non-exposure period Tne2. During a second exposure period the second light source 2 is turned on while during a second non-exposure period the second light source 2 is turned off or shielded.
Based on information received through the operator interface 7, the control means 5 determine a sequence of operation for the first light source 1 and the second light source 2. The control means 5 then control the first light source 1, the second light source 2 and the moving means 8 for exposing the relief precursor P according to the determined sequence. The sequence is such that each of the one or more second exposure periods either fully overlaps with the first exposure period or does not overlap with the first exposure period. The information received through the operator interface 7 may comprise at least one first characteristic representative for the first exposure period Te1 and/or at least one second characteristic representative for the one or more second exposure periods Te2, Te2′.
The at least one second characteristic may comprise any one of the following or a combination thereof: a speed value for the speed of the movement of the second light source 2 during the one or more second exposure steps S2, S2′, a number of times the same second exposure step is repeated, a value representative for a light intensity used during the one or more second exposure periods Te2, Te2′. Typically the second characteristics may comprise for each different second exposure step, a combination of a speed value and a number of repetitions. It is noted that typically also the intensity or power for each second exposure step is entered by an operator, but in most embodiments it is not required to use the intensity or power for determining the sequence. However, in further developed embodiments also the intensity or power may be taken into account.
The at least one first characteristic may comprise any one of the following or a combination thereof: a duration of the first exposure period, a value representative for a light intensity used during the first exposure period Te1. Typically the first characteristic may comprise the duration of the first exposure period. It is noted that also the intensity or power for the first exposure step may be entered by an operator, but in most embodiments it is not required to use the intensity or power for determining the sequence. However, in further developed embodiments also the intensity or power of the first exposure step may be taken into account.
In the embodiment of
The shield 4 is configured to capture at least a portion of the light of the second light source 2 transmitted through the relief precursor P, see arrow L. The shield 4 is non-transparent to electromagnetic radiation emitted from the second light source. The shield 4 has a surface 42, here un upper surface, which is facing the second light source 2 and which is configured to absorb more than 80% of light that is received on said surface, preferably more than 95%. This upper surface 42 may be a black surface. In the illustrated embodiment, the shield 4 is a plate with a flat upper surface 42, but the skilled person understands that the shield may have any suitable shape, and may be e.g. a rod with a black outer surface. The shield 4 may be mechanically coupled to the second light source 2 or may be independently movable. Also the shield 4 is movable back and forward as indicated with arrow A2, in a plane parallel to the plane of the first light source 1. Preferred features of the movable shield can be found in patent application in the Netherlands with application number N2024756 filed on 24 Jan. 2020, which is included herein by reference.
In the embodiment of
As in
In the embodiment of
When determining the sequence to be used, one of the options of
Further
When determining the sequence to be used, one of the options of
In a following step 502, a sequence of operation of the first light source 1 and the second light source 2 is determined based on the received at least one first and/or second characteristic. As criteria for the determination of the sequence of operation is primarily the condition that the sequence is such that each of the one or more second exposure periods Te2, Te2′ either fully overlaps with the first exposure period Te1 or does not overlap with the first exposure period Te1.
Additionally, the method may determine the sequence taking into account other criteria including:
In a step 503, the method comprises exposing the relief precursor according to the determined sequence.
The mode of operation may either be:
Finally in steps 605, 607 and 608 the relief precursor may be exposed according to the sequence corresponding to the selected mode of operation. In this way an operator may operate his machine with fixed sequences for some types of known relief precursors while he may want to rely on the control means for the determination of a sequence for a new and unknown relief precursor.
To illustrate the general principle of operation of the graphical user interface, the edition of field 704 will now be described. When activating the button 714 associated with field 704, a new window 1704 may be opened. In the window 1704, an operator may select one of more options 704a-704c corresponding to the available modes of operation, namely in the example ‘Before Main, ‘After Main’ or ‘Combined’. Once a mode is selected, the activation of a button 750 may close the window 1704, returning to the window 700. It is to be understood that windows similar to window 1704 may be opened to edit each of the editable fields 701-703, 705 and 706. A button 720 may be activated to validate all the fields 701-706 to complete the step of receiving information through the operator interface 7. A button 730 may be activated to cancel the edition of the fields 701-706 since the last step of receiving information through the operator interface. A button 740 may be activated to add more editable fields to the window 700. A skilled person would understand that other ways of editing the graphical interface may be envisaged without inventive skill as long as information may be received from an operator.
In non-illustrated embodiments, a post-treatment unit may be provided to perform a post-treatment on the relief precursor, e.g. washing, drying, post-exposure, heating, cooling, removing of material, etc. Further, in non-illustrated embodiments, a pre-treatment unit may be provided to perform a pre-treatment on the relief precursor, said pre-treatment being selected from the group comprising: cutting, ablation, exposure to electromagnetic radiation, and combinations thereof.
A relief precursor generally comprises a support layer and at least one photosensitive layer. The support layer may be a flexible metal, a natural or artificial polymer, paper, ceramic, or combinations thereof. Preferably the support layer is a flexible metal or polymer film or sheet. In case of a flexible metal, the support layer could comprise a thin film, a sieve like structure, a mesh like structure, a woven or non-woven structure or a combination thereof. Steel, copper, nickel or aluminium sheets are preferred and may be about 50 to 1000 μm thick. In case of a polymer film, the film is dimensionally stable but bendable and may be made for example from polyalkylenes, polyesters, polyethylene terephthalate, polybutylene terephthalate, polyamides and polycarbonates, polymers reinforced with woven, nonwoven or layered fibres (e.g. glass fibres, Carbon fibres, polymer fibres) or combinations thereof. Preferably polyethylene and polyester foils are used and their thickness may be in the range of about 100 to 300 μm, preferably in the range of 100 to 200 μm.
A relief precursor may carry at least one additional layer. For example, the additional layer may be any one of the following: a direct engravable layer (for example by laser), a solvent or water developable layer, a thermally developable layer, a photosensitive layer, a cover layer, a barrier layer, a combination of a photosensitive layer and a mask layer. Optionally there may be provided one or more further additional layers on top of additional layer. Between the different layers described above one or more adhesion layers may be located which ensure proper adhesion of the different layers. Such one or more further additional layers may comprise a cover layer at the top of all other layers which is removed before the imageable layer is imaged. The one or more additional layers may comprise a relief layer, and an anti-halation layer between the support layer and the relief layer or at a side of the support layer which is opposite of the relief layer. The one or more additional layers may comprise a relief layer, an imageable layer, and one or more barrier layers between the relief layer and the imageable layer which prevent diffusion of oxygen. Between the different layers described above one or more adhesion layers may be located which ensure proper adhesion of the different layers.
In a preferred embodiment the relief precursor comprises a support layer made of a polyester of polymer material, and an additional layer made of a directly engravable material such as a resin material. The optional layer may then be a laser ablative layer. In an exemplary embodiment the relief precursor may contain at least a dimensionally stable support layer, a relief layer and an imageable mask layer. Optionally, further layers may be present. There may be a cover layer at the top of all other layers which is removed before the imageable mask layer is imaged. There may be an anti-halation layer between the support layer and the relief layer or it may be located at the side of the support layer which is opposite of the relief layer. There may be one or more barrier layers between the relief layer and the imageable mask layer which prevent diffusion of oxygen. Between the different layers described above one or more adhesion layers may be located which ensure proper adhesion of the different layers. One or more layers may be removable by treatment with a liquid. The liquids used may be the same or different for different layers.
In a preferred embodiment the relief precursor comprises a photosensitive layer and a mask layer. The mask layer may be ablated or changed in transparency during the treatment and forms a mask with transparent and non-transparent areas. Optionally the mask layer and/or the barrier layer are removed in the pre-washing section of the system because they may comprise material which could cause problems in further process steps or during use of the final relief. Underneath of transparent areas of the mask the photosensitive layer undergoes a change in solubility and/or fluidity upon irradiation. The change is used to generate the relief by removing parts of the photosensitive layer in one or more subsequent steps. The change in solubility and/or fluidity may be achieved by photo-induced polymerization and/or crosslinking, rendering the irradiated areas less soluble. In other cases the electromagnetic radiation may cause breaking of bonds or cleavage of protective groups rendering the irradiated areas more soluble. Preferably a process using photo-induced crosslinking and/or polymerization is used.
Liquids which may be used to remove material from the exposed precursor include amongst others: Water, aqueous solutions, solvents and combinations thereof. The nature of the liquid used is guided by the nature of the precursor employed. If the layer to be removed is soluble, emulsifiable or dispersible in water or aqueous solutions, water or aqueous solutions might be used. If the layer is soluble, emulsifiable or dispersible in organic solvents or mixtures, organic solvents or mixtures may be used. In the case of organically developable precursors different organic solvents or their mixtures may be used.
Removal of uncured material from the exposed precursor may also be performed by heating and removal of liquefied material with a developing material. The removal of softened material is achieved by continuously contacting it with an absorbing material. The absorbing developer material may be a non-woven of polyamide, polyester, cellulose or inorganic fibres onto which the softened material is adhering and subsequently removed. Such methods are described for example in U.S. Pat. Nos. 3,264,103, 5,175,072, WO 96/14603 or WO 01/88615. Alternatively WO 01/90818 proposed to treat the exposed relief precursor with a hot gas or fluid jet to remove the non-cured material. In EP-A 469 735 and WO 01/18604 devices capable to perform the above mentioned methods are described.
Whilst the principles of the invention have been set out above in connection with specific embodiments, it is to be understood that this description is merely made by way of example and not as a limitation of the scope of protection which is determined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2027144 | Dec 2020 | NL | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/086474 | 12/17/2021 | WO |
