A heat source may provide heat to an element of a printing system during printing. A heat source may, for example, be provided as part of a printing system to heat printing material disposed on an element of the printing system.
In the following description, for purposes of explanation, numerous specific details of certain examples are set forth. Reference in the specification to “an example” or similar language means that a particular feature, structure, or characteristic described in connection with the example is included in that one example, but not necessarily in other examples.
In a printing system, a heating target may be an intermediate printing material transfer element (e.g. a printing blanket). Printing material may be transferred to the printing blanket before being transferred to a printing target (e.g. paper, card, etc.) to produce printing content. In some examples, the printing material may comprise a carrier oil which may, for example, comprise a suspension of particles that provide color to a printing target. When such printing material is transferred to the printing blanket, heat may be radiated to the printing blanket in order to melt the particles that provide color to provide ink or the like, and evaporate the carrier oil such that the ink or the like may then be transferred to the printing target.
In such cases, if heat is not uniformly received at the printing blanket, carrier oil may not fully evaporate from those parts of the printing blanket where less heat is received. This may cause unevaporated carrier oil to remain on the printing blanket, resulting in “memory content” to be produced in a subsequent printing process. Providing heat such that it is received uniformly along the length of the printing blanket according to the examples described below may inhibit or prevent memory content from being produced.
In addition, in prior art examples where heat is not uniformly received at the printing blanket, to mitigate the effects of memory content, the heat source of a printer may be operated to provide a large overall amount of heat per unit time so that those parts of the printing blanket that receive less heat may receive enough heat to evaporate the carrier oil at those locations. However, use of a heat source which results in heat uniformly being received at the printing blanket would allow the heat source to be operated to provide a lower overall amount of heat per unit time (because less heat being received at certain locations of the printing blanket would not be compensated for by providing a larger amount of heat overall).
Mitigating the effect of memory content may allow colors to be printing in various different orders. For example, in a printer in which the memory content effect is not mitigated, lighter colors (e.g. yellow) may be printed before darker colors (e.g. black). This is because black memory content would be more apparent than yellow memory content in the final printing content being produced. However, in examples in which the memory content effect is mitigated, for example by providing a heat source according to the examples described below, darker colors can be printed before lighter colors without significantly negatively impacting the quality of the printing content.
The heat per unit time generated by the heat source 100 may vary along the heat source 100 such that a first part of the heat source 100 at or close to a first end 108 and a second part of the heat source 100 at or close to a second end 110 radiate a greater amount of heat per unit time than a third part of the heat source 100 disposed between the first part and the second part. In the example of
The heat source 100 may also be referred to as a heating element 100 and the heat generating segments may also be referred to as heat producing portions, e.g. of a heating element.
The heat source 100 may, for example, be for radiating heat onto the intermediate printing material transfer element disposed at a given distance from the heat source 100 such that there is a substantially uniform distribution of heat per unit time (heat power) received along a length of the intermediate printing material transfer element.
The plurality of heat generating segments include a first heat generating segment 102, a second heat generating segment 104 and a third heat generating segment 106. In the example of
In the example of
The heat source 100 may comprise a filament, for example, a filament for a halogen bulb, such as a tungsten filament. In such examples, the plurality of heat generating segments 102, 104, 106 may be coiled segments of the filament, which may be spaced apart by segments of the filament that are not coiled. In other examples, the heat source 100 may comprise a coiled filament having a varying density of coiled loops along its length. For example, the heat source 100 may be more densely coiled at parts at or close to the first end 108 and second end 110 such that a greater amount of heat per unit time is generated at the parts of the heat source 100 at or close to the first end 108 and second end 110 than between these parts.
The heat generating segments 102, 104, 106 may generate heat when electrical power is supplied to the filament. It will be appreciated that although other parts of the heat source 100 may generate some heat, heat generating segments 102, 104, 106 as referred to herein are those segments of the heat source, for example coiled segments of a filament, which generate significant amounts of heat.
In other examples, the heat source 100 may comprise a resistive element the resistance of which varies along the length of the heat source 100. For example, heat source 100 may comprise a continuous resistive element with the parts of the resistive element at or close to the first and second ends 108, 110 having a higher resistance than the parts of the resistive element in between the parts at or close to the first and second ends 108 and 110, such that the parts of the resistive element at or close to the first and second ends 108 and 110 radiate a greater amount of heat per unit time than the parts in between the parts of the resistive element at or close to the first and second ends 108 and 110. In other examples, the heat source 100 may comprise spaced apart resistive elements of high resistance such that spaced apart elements define heat generating segments 102, 104, 106. It will be understood that the higher the electrical resistance of an element/segment, the more heat it will generate when electrical power is supplied to it. Examples of the heat source 100 may include any heat source which can be provided segmented to comprise heat generating segments 102, 104, 106.
In some examples, the heat source 100 may be part of a heater.
As described above, a printing blanket may be placed at the printing blanket location 302 in the printer 300. A printing blanket thus placed is an example of a heating target where heat radiated from the heater 200 is received. In the example of
It will be appreciated that printer 300 may also comprise other elements not shown in
The printer 300 may comprise a controller and a data storage unit (not shown) which together control the functioning of the printer 300. The printer 300 may also comprise a user interface (not shown) in order for the user to provide instructions to the printer 300.
On the other hand, curve 404 is a heat profile of heat power received from heat source 100 at the heating target positioned at a given distance. Curve 404 is an example of a heat profile of heat received at the printing blanket location 302 referred to in relation to
A method of selecting a heat radiating pattern for a heat source will now be described. The method is for selecting a heat radiating pattern such that a heat profile at a heating target of heat radiated from the heat source having the selected heat radiating pattern from a specified distance is substantially the same as a desired heat profile of heat received at the heating target.
The method may, for example, be executed by a controller of a computing system. An example of a computing system 500 is shown in
Method 600 is illustrated in the flow diagram of
At 604, data indicating a specified distance between the heat source and the heating target is received.
For example, a user may input data indicating the specified distance and an input heat radiating pattern, which data is received by the controller 502. The user may thus specify the distance between the heat source and the heating target and the input heat radiating pattern. The input heat radiating pattern may, for example, specify a dimension and a relative position of each of the heat generating segments of a heat source according to an example described above. The data may be input using a data input device connected to the computing system 500 such as, for example, a mouse, a keyboard, or another input device for use with the computing system 500.
In other examples, the controller 502 may specify an input heat radiating pattern without a user input. For example, the controller 502 may specify an input heat radiating pattern by selecting a heat radiating pattern from a list of heat radiating patterns. The list of heat radiating patterns may comprise heat radiating patterns known to provide certain heat profiles at a heating target at respective specified distances, for example. The controller 502 may specify an input heat radiating pattern from this list which provides a heat profile close to the desired heat profile at the heating target at a distance equal to or close to the specified distance, for example. In some examples, the controller 502 may specify the input heat radiating pattern by performing a preliminary calculation. For example, the preliminary calculation may comprise estimating an input heat radiating pattern estimated to provide a heat profile close to the desired heat profile at the heating target at the specified distance.
At 606, a heat profile at the heating target of heat radiated from the heat source having the input heat radiating pattern from the specified distance is determined. For example, the heat profile of the input heat radiating pattern may be determined by calculating the heat power received at a plurality of points along a length of the heating target. The received heat power may, for example, be determined as heat per unit time received at a plurality of points along a length of the heating target.
An example of the calculation of the heat power received at a plurality of points along a length of the heating target is described with reference to the heating arrangement of
In this example, Px is the total heat power received at point 702 from segment 710, I0 is the heat power per unit length of the segment 710 (e.g. in units of Watts per millimetre), D is the distance between the heating target 704 and the heat source 708, and θ1 and θ2 are angles with respect to the segment 710 and the given point 702. Angle θ1 has its vertex at point 702 and is the angle between a line 714 connecting the point 702 to a first end 710a of the segment 710, and a line 716 originating at point 702 and perpendicular to the heating target 704. Angle θ2 has its vertex at point 702 and is the angle between a line 718 connecting the point 702 to a second end 710b of the segment 710, and the line 716. The heat power received from segment 712 at point 702 may be calculated in a similar manner. Heat power received at point 702 from all segments specified in the input heat radiating pattern may be calculated in a similar manner and summed to give the total heat power received at point 702 from the heat source 708. Heat power received at a plurality of points along the length of the heating target 704 may be calculated using equation (1) in this way, for example. Thus, in this example, the heat profile of heat power received at the heating target 704 due to the input heat radiating pattern may be calculated using equation (1).
The heat profile of the input heat radiating pattern represents power received at the heating target as a function of a length along the heating target. The determined heat profile of the input heat radiating pattern is compared to the desired heat profile at 608 of method 600.
The desired heat profile may, for example, be specified by the user. For example, data indicating the desired heat profile may be input by the user into computing system 500 using input devices of the computing system 500.
In some examples, the desired heat profile may be a flat heat profile. A flat heat profile, for example, indicates that heat is received at the heating target uniformly along a length of the heating target such that heat power as a function of position along a length of the heating target is substantially constant.
On the basis of the comparison at 608, it is determined whether or not the input heat radiating pattern meets a selection criteria at 610. The selection criteria, for example, may specify a level of similarity between the input heat radiating heat profile and the desired heat profile. If the level of similarity is achieved by the input heat radiating heat profile when compared to the desired heat profile, the selection criteria may be determined to be met.
For example, when the desired heat profile is a flat heat profile (e.g. as indicated by curve 404 of
At 612 of method 600, the input heat radiating pattern is selected if the input heat radiating pattern meets the selection criteria. However, if the input heat radiating pattern does not meet the selection criteria, 602 to 612 of method 600 are repeated at 614. Thus, method 600 may be iterated until an input heat radiating pattern is found which meets the selection criteria and therefore substantially provides that the desired heat profile is received at the heating target at the specified distance.
Although the flow diagram of
In examples, a heat source having a plurality of heat generating segments according to the selected heat radiating pattern may be made. For example, a heat source according to the selected heat radiating pattern may be made by coiling a filament such that said filament has the selected heat radiating pattern.
The heat source made according to the method and having the selected heat radiating pattern may be incorporated into a printing system 300 such as that described above, such that the heat source is disposed at the specified distance from the heating target.
Instructions which cause examples of the method 600 to be implemented may be specified using a computer programming language. Examples of programming languages include MATLAB, C++, C, FORTRAN, as well as numerous others.
It is to be understood that any feature described in relation to any one example may be used alone, or in combination with other features described, and may also be used in combination with any feature of any other of the examples, or any combination of any other of the examples. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the accompanying claims.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2017/077369 | 10/25/2017 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2019/081017 | 5/2/2019 | WO | A |
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MUTOH's Infra Red Dryers Optional Infra Red Dryer for Mutoh Solvent & Direct Textile Printers, Jul. 6, 2011, http://www.mutoh.eu/Portals/0/MutohData/DocumentLibrary/Public%20Zone/Downloads/Brochures/Brochure%20IRDryer.pdf. |
Number | Date | Country | |
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20200247168 A1 | Aug 2020 | US |