Testing for wiping pre-treatment of print media

There is disclosed a non-transitory machine-readable medium encoded with instructions executable by a processor and comprising instructions to: control print apparatus to print a test pattern 11 on a test region of a print medium 4; receive test data relating to the test pattern 11 printed on the print medium 4 from a sensor 8; analyse the test data with reference to baseline data to determine if the test pattern 11 satisfies a print quality criterion; output an instruction to operate the print apparatus in a first mode, in which a pre-printing treatment is not applied to the print medium, in response to determining that the test pattern 11 satisfies the print quality criterion, the pre-printing treatment comprising wiping a printing surface of the print medium with a wiper element 10, 20; and output an instruction to operate the print apparatus in a second mode, in which the pre-printing treatment is applied to the print medium 4, in response to determining that the test pattern 11 satisfies the print quality criterion.

Some printing media may contain substances which over time may migrate to the printing surface. This phenomenon may occur for instance when rolled media is exposed to high temperatures, for example, during transportation or storage, or simply when media is stored for some time before use.

For example, print media such as vinyl and PVC banners may contain plasticizers to increase their flexibility, and these additives may tend to migrate to the surface. Other substances that may exhibit a tendency to migrate to the printing surface may be, for example, adhesives or silicones present in adhesive media.

The presence in some printing media of substances, such as plasticizers or adhesives, which over time may migrate to the printing surface forming micro-droplets or random patterns, may affect the quality of printed images.

A substance that has migrated to the printing surface, and/or contaminants present in the form of droplets, micro-droplets or moisture on the surface, may create differences in the surface tension, and it may therefore happen that printing fluid does not deposit uniformly. When printing on such a medium, for example with latex printing fluids, defects such as for example graininess, pinholes or coalescence may appear in the printed image.

In implementations disclosed herein the printing quality may be improved by wiping the printing surface of the media before printing, so as to spread over a larger surface area, i.e. more evenly, substances that may be present on the surface in the form of micro-droplets or the like.

Examples of a print apparatus as disclosed herein are illustrated inFIG. 1. Example apparatus may comprise a print zone1where a printing fluid may be deposited on the printing surface5of a print medium4from a printhead2. Input rollers3may cause the advance of the print medium4towards the print zone1, in a direction of print media advance shown by arrow A inFIG. 1.

According to examples disclosed herein, a wiping element10may be provided in the apparatus before the print zone1, i.e. upstream of the print zone, in the direction of print media advance A through the apparatus, so that it slips in contact with the print medium4when the print medium is advanced towards the print zone1, thereby wiping the printing surface5of the print medium4before printing.

By “slip” or “slipping” it is meant herein that the wiping element is in contact with the printing surface of the print medium, and has a different speed from that of the printing surface in the area of contact, such that during operation there is a non-zero relative speed between the wiping element and the printing surface. In other words, there is relative sliding movement between the wiping element and the printing surface whilst they are in contact. The relative speed may be caused for example by the wiping element having a higher speed than that of the print medium, or by the wiping element being stationary or having a lower speed than that of the print medium.

The friction caused by wiping may have the effect that substances such as plasticizers that may be present on the printing surface in a non-continuous or uneven distribution, for example in the form of micro-droplets, clots, lumps, or other irregularities, are spread or distributed more evenly. For example, a droplet would be “flattened” on the media and spread over a larger area.

This allows reducing the differences in surface tension between different areas of the print medium and reducing potential defects in the printed image that may be associated with these differences. The quality of the printed image may therefore be improved.

The effect on the printed image of other contaminants present on the surface of the media, for example small amounts of grease from fingerprints due to media handling, may also be reduced.

As shown inFIG. 1an example print apparatus may further comprise a sensor8for monitoring a printed region of the print surface5of the print medium4. In this example, the sensor8is disposed downstream of the printhead2. In this example, the sensor8comprises a spectrophotometer to monitor color properties of a pattern printed on the print medium. In other examples, other sensors could be used, for example an optical sensor and more particularly a line sensor.

The sensor is to monitor properties of a pattern printed on the print medium related to print quality, in particular properties which are affected by substances such as plasticizers when migrated to the printing surface5of the print medium.

For example, one such property is the coalescence of print agent droplets (such as ink droplets), which may be excessive when such substances are migrated to the printing surface. Color may be affected by coalescence, in particular because droplets may coalesce in an unintended manner and therefore result in a different color than intended. A spectrophotometer is to monitor color properties of a printed pattern (or a portion of a printed pattern) so that a color difference between the pattern and a baseline pattern may be determined, either by the spectrophotometer or by a separate controller.

Coalescence may also affect the geometric accuracy of a print pattern, as can be measured by a line sensor. In particular, coalescence may adversely affect the geometric definition of a line or border of a printed portion of the print pattern. For example, a gap between two adjacent printed regions of a pattern may be reduced relative a baseline pattern owing to coalescence effects, for example the gap may be reduced by an amount between 0.01 mm to 0.1 mm. A line sensor may be used to determine the dimension of the gap as compared to a corresponding dimension in a baseline pattern to determine the difference.

As shown inFIG. 1, the print apparatus further comprises a controller7. In this example, the controller7is to control the printhead2and the sensor8. In other examples, there may be separate controllers for these components.

The controller7is to control the operation of the printhead2to selectively eject a print agent onto the print medium (i.e. to print), based on a print job instruction. For example, the controller7may control the printhead2to print a test pattern on the print medium, as will be described in detail below.

The controller7is to receive an output from the sensor8relating to a pattern printed on the print medium. In this particular example, the controller7is to control the sensor8to monitor a particular portion of a pattern, in particular a test pattern printed on the printed medium, and is to receive test data relating to the test pattern from the sensor8. In this particular example, the sensor8is a spectrophotometer, and the controller7is to receive test data relating to the color of a portion of a test pattern, as will be described in detail below.

Further, the controller is to analyse the test data with reference to baseline data, as will be described in detail below.

FIG. 2shows a further example print apparatus which differs from that described above with respect toFIG. 1in that the wiping element10is selectively moveable from a disengaged configuration (FIG. 2) to an engaged configuration (as shown inFIG. 1) upstream of the print zone with respect to a direction of print media advance through the print apparatus. In the disengaged configuration the wiping element10is spaced apart from the path of the print medium4so that in use it does not engage the printing surface of the print medium4. For example, in example apparatus in which the printing surface5faces upward and the wiping element10is disposed over the print medium4, as shown inFIGS. 1 and 2, the wiping element10may be suspended over and spaced apart from the printing surface (or a media advance path for the print medium) by a separation distance such as between 1 and 5 cm. In the engaged configuration the wiping element is to engage the printing surface5of the print medium4to wipe it (i.e. for relative sliding movement in contact with the printing surface), as described above. For example, in the apparatus ofFIG. 2, the wiping element10moves downwardly from the disengaged configuration to the engaged configuration in which the wiping element10is in contact with the printing surface5of the print medium, or is aligned with a media advance path for the print medium to contact the printing surface5of a print medium to be conveyed past the wiping element10. As shown inFIG. 2, the print apparatus further comprises an actuator9for moving the wiping element10between the disengaged and engaged configurations. In this example, the controller7is to control the actuator for moving the wiping element10between the disengaged and engaged configurations.

In this example, the actuator9is to move the wiping element10between the disengaged and engaged configurations by pivoting a pivotable element, however it will be appreciated that other arrangements may be used in other example print apparatus. For example, the wiping element may be mounted on a rail suspended over a media path for the print medium, and may be coupled to a linear actuator for driving the wiping element along the rail between a disengaged configuration and an engaged configuration.

An example method300of testing for wiping pre-treatment of print media will now be described with reference to the flowchart ofFIG. 3(i.e. testing to determine whether such pre-treatment is to be applied). For illustrative purposes, the method will be described with reference to the print apparatus described above with reference toFIG. 2. In this example, the print apparatus is loaded with a print medium comprising PVC containing additive plasticizer.

In block302, the controller7initiates a print operation to print a test pattern on a test region of the printing surface5of the print medium, without pre-curing the test region. The controller7controls the sensor8to monitor the test region.

In this example, the controller7causes a test pattern to be printed comprising a calibration pattern including adjacent blocks of different colours. In some examples, the calibration pattern may include an arrangement of lines, such as may be used for printhead alignment operations.

The sensor8outputs test data relating to the pattern. In this particular example, the sensor8is a spectrophotometer to monitor color properties of the test pattern, and the controller7controls the sensor8to output test data relating to one or a plurality portions of the test pattern, which is received by the controller7in block304.

In this example, the controller7retrieves pre-stored baseline data in block306, in particular pre-stored data relating to the one or plurality of portions of a baseline pattern corresponding to the test pattern.

In block308, the test data is analysed to compare the test pattern with the baseline pattern. In this particular example, the analysis is a color difference analysis using data relating to the one or plurality of portions of the test pattern. In particular, the color difference analysis is used to determine a color difference between the respective portions of the test pattern and the baseline pattern. Such color difference analysis may be conducted to determine a color difference in units of ΔE.

In this particular example, the spectrophotometer9and controller7are to analyse a color difference in units of ΔE as determined by the Delta-E 2000 standard introduced by the CIE organisation (International Commission on Illumination).

In other examples, for example when the sensor8is an optical sensor, the controller may compare other properties of the test pattern and baseline pattern, for example geometric properties relating to the alignment and position of features in the respective pattern, such as a size of a gap between printed features, or a thickness of a line. For example, the print quality criterion may define an alignment tolerance between a position of a line within the test pattern and a baseline position for the line. For example a tolerance of between 0.01 mm to 0.1 mm may be defined, such as 0.05 mm.

In block310, the controller determines, based on the analysis, whether the test pattern satisfies a pre-determined print quality criterion. In this particular example, the print quality criterion is set so that satisfactory print quality is determined when each of the color difference comparisons of the respective one or plurality of portions of the test pattern that are monitored result in a measured color difference of less than 4ΔE. In other examples the threshold ΔE may be different, for example 3ΔE or 5ΔE, or a different standard or unit may be used.

In block312, in response to determining that the print quality criterion is satisfied, the controller7outputs an instruction to operate the print apparatus in a first mode in which a wiping pre-treatment is not applied to the print medium.

Conversely, in block314, in response to determining that the print quality criterion is not satisfied, the controller7outputs an instruction to operate the print apparatus in a second mode in which a wiping pre-treatment is applied to the print medium.

In this particular example, the instruction to operate the print apparatus in the first mode is issued in the form of a controller setting for operation of the print apparatus (i.e. a parameter stored in a memory of the controller and retrieved in a subsequent print operation). In a subsequent print operation, the actuator9causes the wiping element10to move to or remain in the disengaged configuration. Similarly, in this particular example the instruction to operate the print apparatus in the second mode is issued in the form of a controller setting for the print apparatus, based on which in use the actuator9causes the wiping element10to move to or remain in the engaged configuration. In other examples, the instruction to operate the print apparatus in the first mode or second mode may result in the actuator9causing the wiping element10to move to or remain in the disengaged configuration or engaged configuration respectively in anticipation of a subsequent print operation.

In yet further examples, the instruction to operate the print apparatus in the first or the second mode may take different forms. In particular, where a print apparatus does not include a mechanism for actuating a wiping element to move between a disengaged configuration and an engaged configuration, the instruction to operate the print apparatus in the second mode may comprise a visual or audible instruction issued to an operator to manually install such a wiping element or wiping element assembly, such as the removable wiping element assembly as will be described below with respect toFIGS. 8-10. For example, a visible instruction may be issued via a display of the print apparatus. In some examples, the visible instruction may include technical or advisory information regarding the color difference or other monitored property. For example, when there is a low color difference (e.g. 1ΔE or 2ΔE) a notification may be displayed that no wiping pre-treatment is to be conducted. For an intermediate color difference (e.g. 3ΔE or 4ΔE), a notification may be displayed that a wiping pre-treatment may improve print quality so that a user or operator can elect whether to apply the wiping pre-treatment. For a high color difference (e.g. more than 4ΔE), a notification may be displayed that wiping pre-treatment should be applied to prevent poor print quality.

A further example method400of testing for wiping pre-treatment of a print medium will now be described with reference toFIGS. 4 and 5.

The further example method400differs from the method300described above with respect toFIG. 3with regards to the generation of baseline data.

In block302, the test pattern is printed on the printing surface5of the print medium4as described above.FIG. 5Ashows the test pattern11printed on a test region of the printing surface5.

Printing may include curing print agent after ejection of the print agent onto a print medium, for example by applying radiative or convective heat to the printing surface. In block402, curing of the test pattern11is extended over an extended area15(i.e. extended beyond the test pattern11, as shown inFIG. 5B) covering both the test pattern11and an un-printed baseline region12of the printing surface5of the print medium4. Curing the un-printed region adjacent the test pattern11can cause plasticizer and other substances which have migrated to the printing surface5to at least partially evaporate in this region, thereby mitigating against adverse effects of plasticizer. In other examples, post-printing curing of the test pattern11, and pre-printing curing of the baseline region12may be conducted separately.

In block404, a baseline pattern13(as shown inFIG. 5C) corresponding to the test pattern is printed on the baseline region12of the printing surface which was previously cured (in block402). As described above, post-printing curing of the baseline pattern13follows printing (as shown inFIG. 5D, which shows a post-printing curing region16over the baseline region12). In this particular example, the print apparatus comprises a convective heater extending over the width of the print medium, and the print apparatus is to move the print medium4relative the heater so that the respective regions11,12,15of the print medium4are cured as described above. In particular, the print apparatus is configured so that portions of the print medium4heated by the heater during curing reach a temperature of between 100° C. and 120° C.

In block406, test data and baseline data are received at the controller7from the sensor8based on the sensor8monitoring the test pattern11and the printed baseline pattern13respectively.

In blocks310,312and314the method proceeds as described above with respect to the method300ofFIG. 3to analyse the test data, determine whether the test pattern meets the print quality criteria, and issue an instruction to operate the print apparatus in the first mode or the second mode accordingly. The applicant has found that printing a baseline pattern13may eliminate printing artefacts and effects that are not caused by the presence of plasticizer and other substances migrated to the surface of a print medium. In particular, it will be appreciated that the baseline pattern is printed under the same conditions as the test pattern, except that the baseline pattern is printed on a pre-cured portion of the print medium.

FIG. 6shows a further example method600of testing for a wiping pre-treatment and conducting a print operation.

The method600differs from the method300described above with respect toFIG. 3in that the baseline data is retrieved from a database. In particular, the test pattern is printed (block302) and the test data is received (block304) as described above. According to the method600, in block602medium data is received, for example from a user input identifying the type of print medium (e.g. the composition of the medium, the color of the printing surface of the print medium), or from a print job instruction containing medium data.

In block604, the baseline data is retrieved from a database based on the medium data. In particular, in this example the database is stored in a memory, for example a memory of the controller7or of a remote system, and is correlated by medium data such as medium type and color. Accordingly, in block604, the controller7looks up and retrieves pre-stored baseline data form the database based on the medium data.

In blocks308,310,312,314the method600proceeds as described above with respect to the method300ofFIG. 3. In particular, the test data is analysed with respect to the baseline data in block308. In block310it is determined whether the test pattern satisfies a print quality criterion.

In block312, an instruction is output to operate the print apparatus in the first mode in response to a determination that the test pattern satisfies the print quality criterion. In block606, the controller7processes a print job received at the print apparatus with the print apparatus in the first mode of operation such that the wiping element10remains or is moved to the disengaged configuration. In other such examples where the wiping element10is not moveable by an actuator, a user or operator may be instructed to ensure that the wiping element is in a disengaged configuration or is not installed (for example by removing the wiping element or moving it to a disengaged configuration). In this example, the print job is received at the print apparatus prior to conducting the method600, and the method600including both testing for the wiping pre-treatment and conducting the print operation is initiated in response to receiving the print job.

In response to a determination that the test pattern does not satisfy the print quality criterion, an instruction is output to operate the print apparatus in the second mode in block314. As previously described, in this example the instruction is in the form of a print apparatus setting stored in a memory, for example a memory of the controller7.

In block608, the controller7proceeds to execute the print job and determines that the print apparatus setting for the wiping element10indicates that the wiping element10is to be applied. Accordingly, responsive to a determination by that the wiping element10is not currently engaged (for example by reference to an output of the actuator9or a control log for the actuator9stored in memory of the controller7) the controller7causes the actuator9to move the wiping element10from the disengaged configuration to the engaged configuration.

In block610, a print operation is conducted according to the print job such that as the print medium moves relative the wiping element10, the wiping element10engages the printing surface5of the print medium4. Accordingly, and as described above, plasticizer and other substances which may have migrated to the printing surface may be wiped, partially removed and/or redistributed to mitigate against the adverse printing artefacts of such substances.

The applicant has found that testing for a wiping pre-treatment, in particular by printing a test pattern and comparing to baseline data, enables the wiping pre-treatment to be applied when it is most effective. As a corollary, the wiping pre-treatment may not be applied when it is less effective, for example when printing defects or artefacts are unrelated to the presence of plasticizer or other substances that may have migrated to the surface of the print medium, or when there are no such printing defects. Testing for the wiping pre-treatment in this way may enable a service life of a wiping element to be maintained, and running costs to be reduced.

FIG. 7shows a non-transitory machine-readable medium702encoded with instructions executable by a processor704. In an example, the instructions include instructions to print a test pattern, receive test data from a sensor, analyse the test data with reference to baseline data, determine if the test pattern satisfies a print quality criterion based on the analysis, and to output an instruction to operate a print apparatus in either a first mode or a second mode accordingly as described above with respect to the method300depicted in the flowchart ofFIG. 3.

FIG. 8shows schematically examples of print apparatus also comprising a print zone1, a printhead2, input rollers3to cause the advance of a print medium4in a direction of print media advance A, a controller7and a sensor8. The print medium4may be fed from a media roll6.

In examples such as shown inFIG. 2, the wiping element may be a wiping roller20that is provided in the media advance path before the print zone1and slips in contact with the printing surface5of the print medium4to wipe it.

In some examples, the angle through which there is contact between the wiping roller20and the print medium4is between 10° and 120°.

A wiping roller may have a relatively small contact area with the print medium and still provide a wiping action. Consequently it may be fitted in the media advance path taking up a relatively small space and without affecting the apparatus footprint.

In some examples the back tension of the print medium4in the advance path provides a degree of pressure to apply the medium4against the wiping roller20and maintains the contact between medium and roller. In examples disclosed herein, the back tension may be between 20 and 40 N/m.

In some implementations of print apparatus as disclosed herein, such as illustrated inFIG. 9a, the wiping roller20comprises a layer of elastic material21, for example, attached on a rigid tubular core22.

The layer of elastic material21may be compressed when applied against the print medium, so it may allow maintaining the wiping roller20in contact with the printing surface5along all the width of the print medium4even if there is some degree of misalignment, and therefore may allow relatively uniform wiping, avoiding local defects.

In some examples, dimensions for a wiping roller20may be between 50 and 60 mm for the diameter D of the core22, and between 4 and 10 mm for the thickness t of the layer of elastic material21.

In some examples, such as illustrated inFIG. 9b, the wiping roller20comprises a sheath23of textile material covering the layer of elastic material21. The sheath23may be made for example of polyester microfiber or suede.

The presence of a sheath23may improve the mechanical resistance of the wiping roller20. Furthermore, maintenance may be simplified by the fact that once the wiping surface becomes affected by wear and/or by having plasticizer or similar substances adhered thereon, as a consequence of use, it is possible to substitute the sheath.

In some implementations of a wiping element such as a wiping roller, both with or without a sheath of textile material, the elastic material may be foam, or a soft rubber. In some examples it may be foam rubber, that is, rubber having an air-filled matrix structure obtained by using a foaming agent. For example, the layer of elastic material21may be of polyurethane (PU) foam rubber, which is also wear resistant and compatible with printing fluids.

In some examples of implementations disclosed herein, the maximum compressibility of the layer of elastic material, defined as the maximum compression the material may undergo while remaining elastic, is at least of 50%. With a 50% maximum compressibility, for example, a layer of elastic material with a thickness of 5 mm may undergo a deformation of up to 2.5 mm in a direction perpendicular to the contact surface, for adapting to misalignments of the print medium.

In some examples, implementations of print apparatus disclosed herein comprise a motor to drive the wiping roller in rotation.FIG. 10for example shows examples in which a motor30with an output shaft31is mounted on the frame40of the apparatus. In some examples the motor may be for example a DC motor controlled with an encoder (not shown).

In some examples, such as shown inFIG. 10, the wiping roller20comprises a driving pinion24and the motor30drives the wiping roller20in rotation through a transmission32between the motor output shaft31and the driving pinion24. In an example such as that ofFIG. 10the transmission32may be a gear transmission and may comprise a transmission pinion33intended to mesh with the driving pinion24.

Also visible inFIG. 10is that in some implementations of a print apparatus with a wiping roller as disclosed herein, the wiping roller20may be mounted on a pair of idle support rollers41(one visible inFIG. 10). The wiping roller20is provided with a cylinder section25for resting on the support rollers41.

In implementations as disclosed herein, a wiping roller20for wiping the printing surface of a print medium, for example such as disclosed above in relation toFIGS. 9a, 9band10, may be provided as a kit, or as part of a kit, to be installed in a print apparatus. The kit may also comprise a driving motor, and may also comprise a transmission.

In some examples, such a wiping roller20may comprise as disclosed above a rigid core22, a layer of elastic material21attached to an outer surface of the rigid core, and a driving pinion24. In some examples it may also comprise a sheath23of textile material.

In some implementations it may be foreseen to install a wiping roller20, for example having a layer of elastic material21and a driving pinion24, in a print apparatus comprising a motor and transmission, in order to print on some kind of print media such as a vinyl banner, which contain substances that may migrate to the printing surface.

It may also be foreseen in some implementations to remove the wiping roller20from the print apparatus and change it with a plain roller that is not provided with a layer of elastic material or a driving pinion, for example in order to print on other kinds of print media, without prior wiping of the printing surface.

In examples according to some implementations of a print apparatus, the wiping element10may be stationary. For example, the wiping element10may comprise a wiping surface, flat or curved, against which the print media slips in order to be wiped.

The material of the wiping surface of a wiping element according to examples as disclosed herein may have a dynamic friction coefficient below 0.7 with respect to vinyl print media, in order to avoid affecting the accuracy of the print media advance.

Implementations of a method for printing are illustrated schematically by the flowchart ofFIG. 11, and may comprise, in block1102, spreading over a larger print medium area, by wiping, amounts of a substance that may migrate through a print medium and that is present on the printing surface of a print medium, before printing on the print medium in block1104. The method for printing may correspond to the printing operation described above with respect to block610ofFIG. 6.

In some examples, the wiping operation in block1102is performed with a wiping roller slipping in contact with the printing surface of the medium, such as examples of a wiping roller20as disclosed above. Slipping between the wiping roller and the print medium, and therefore wiping, may occur while the print medium is advancing, but also while it is stationary, for example when printing is performed in swaths on a print medium while stationary, and the print medium is advanced between swaths.

According to some implementations disclosed herein, in block1102the wiping roller may be rotated, for example employing a motor, in order to cause slipping of the wiping roller with respect to the print medium at least when the print medium is stationary. It may be rotated for example with an angular speed between 20 and 40 rpm.

In some implementations, example methods may involve rotating the wiping roller with an angular speed that causes the relative tangential speed of the surface of the wiping roller with respect to the printing surface of the print medium to be between about 2 in/s and about 5 in/s (between about 50.8 mm/s and about 127 mm/s), for example between about 3 in/s and about 4 in/s (between about 70.6 mm/s and about 101.6 mm/s).

During the wiping operation in block1102, in some examples of the method a tension of the print medium maintains contact between the wiping roller and a printing surface of the print medium.

Some implementations of such methods may be performed by print apparatus as disclosed above.

In examples of printing operations in which implementations of this disclosure are put in practice, a wiping roller20such as shown inFIGS. 2 and 3amay be employed. Further features may be for example as follows:tubular steel core with an outer diameter D=50 mmPU foam rubber layer adhered on the steel core, thickness t=5 mmfoam rubber layer elastically compressible to 50% of original thicknessdynamic friction coefficient of the foam material on vinyl media μk=0.6angle of contact of the wiping roller with the media: 110°back tension of the medium: 30 N/mspeed of rotation of the wiping roller: minimum 30 rpm

Examples in the present disclosure can be provided as methods, systems or machine-readable instructions, such as any combination of software, hardware or the like. Such machine-readable instructions may be included on a machine-readable storage medium (including but is not limited to disc storage, CD-ROM, optical storage, etc.) having machine-readable program codes therein or thereon.

The present disclosure is described with reference to flow charts and/or block diagrams of the method, devices and systems according to examples of the present disclosure. Although the flow diagrams described above show a specific order of execution, the order of execution may differ from that which is depicted. Blocks described in relation to one flow chart may be combined with those of another flow chart. It shall be understood that each flow and/or block in the flow charts and/or block diagrams, as well as combinations of the flows and/or diagrams in the flow charts and/or block diagrams can be realized by machine-readable instructions.

Such machine-readable instructions may also be stored in a machine-readable storage that can guide the computer or other programmable data processing devices to operate in a specific mode.

While the method, apparatus and related aspects have been described with reference to certain examples, various modifications, changes, omissions, and substitutions can be made without departing from the spirit of the present disclosure. It is intended, therefore, that the method, apparatus and related aspects be limited only by the scope of the following claims and their equivalents. It should be noted that the above-mentioned examples illustrate rather than limit what is described herein, and many various design implementations are possible without departing from the scope of the appended claims. Features described in relation to one example may be combined with features of another example.

Although a number of particular implementations and examples have been disclosed herein, further variants and modifications of the disclosed devices and methods are possible. For example, not all the features disclosed herein are included in all the implementations, and implementations comprising other combinations of the features described are also possible.