Patent Application
20150072608
The present invention relates to a method for conditioning a recording medium storage enclosure in a printing system. The present invention further relates to a printing system comprising a printing station and a recording medium storage enclosure. The present invention further relates to an air flow kit for conditioning a recording medium storage enclosure.
In a known method for conditioning a recording medium enclosure in a printing system a recording medium is provided in the form of a roll of an endless web wound on the reel inside a recording medium enclosure. The printing system further has a feeding path leading from the reel to a printing station for feeding a portion of the recording medium, a cutting device disposed at the feed path for cutting the web, and a feed control system.
In printers in which paper sheets or similar image receiving sheets are used as recording media, a tendency of the paper to cockle may occur. The cockling phenomenon is related to the fact that paper and similar materials tend to absorb humidity from ambient air and to expand and contract in accordance with their humidity content. When there exists a gradient in humidity within the paper, or any other non homogeneous state of humidity in the paper, then the more humid portion of the paper will expand more than the drier portion, which leads to the production of cockles or wrinkles.
In case the printing system terminates a print operation, a leading edge of the web, which has been cut after printing, is located in the feed path. Then, an end portion of the web that is present in the feed path inside the recording medium enclosure will be exposed to ambient air from both sides and can therefore absorb a large amount of moisture.
In order to reduce a moisture absorption by the end portion of the web the feed control system of the printing system is adapted to withdraw that end portion of the web onto the peripheral surface of the roll when the printing system is in a non-printing condition. When the print operation is continued, the web has to be feed again into the feed path, which needs a separating step for separating the leading edge from the surface of the roll, leading to a loss of productivity during resumption of the print operation. A gradient in humidity within the paper will still grow in time as the outer layer of the roll is exposed to ambient air, which will eventually lead to a higher humidity content of the leading end portion of the web.
In an aspect of the present invention, a method for conditioning a recording medium storage enclosure in a printing system is provided, which is capable of reducing effects of ambient air conditions on humidity conditions of a recording medium in a recording medium storage enclosure.
In a first aspect of the present invention a method for conditioning a recording medium storage enclosure in a printing system is provided, the recording medium storage enclosure comprising an exit opening being arranged at a first end of the recording medium storage enclosure, which exit opening is configured for releasing a portion of a recording medium towards a printing station of the printing system, the method comprising the steps of:
The recording medium storage enclosure is configured for storing a recording medium. The recording medium storage enclosure comprises an exit opening, which is arranged at a first end of the recording medium storage enclosure. A shape of the exit opening is suitably selected for guiding a portion of the recording medium from inside the recording medium storage enclosure outward. The recording medium storage enclosure may be substantially closed, and may be partially closed. Preferably the recording medium storage enclosure is for the most part closed. Openings in the recording medium storage enclosure are possible in so far as these openings do not prohibit the circulation of a portion of the air flow in the recording medium storage enclosure.
In the air flow step a) an air flow is provided inside the recording medium storage enclosure in a main air flow direction adjacent to the exit opening. The main air flow direction is the predominant flow direction of the air flow. The air flow is provided in the main air flow direction adjacent to the exit opening in order to minimize a flow of ambient air through the exit opening. Attributes of the air flow, such as a flow rate and a distance between the main air flow direction and the exit opening, may be suitably selected. The main air flow direction is aligned along a direction of the exit opening, which is substantially perpendicular to a feeding direction of a recording medium through the exit opening. As a result an air flow through the exit opening is minimized.
It has been found that the feeding direction of the recording medium is usually a most sensitive direction towards an air flow through the exit opening. In case a different direction of the exit opening is more sensitive, the main air flow may suitably be adapted, such that it is perpendicular to the more sensitive direction of the exit opening. In a circulating step b) a first portion of the air flow, which is provided in the main air flow direction, is circulated between the first end and the second end of the recording medium storage enclosure opposite of the first end. Circulating the first portion of the air flow means that the first portion is moved from the first end to the second end of the recording medium storage enclosure, and sub sequently is moved back from the second end to the first end of the recording medium storage enclosure. Means may be provided in the recording medium storage enclosure for supporting the circulation of the first portion of the air flow between the first end and the second end (e.g. air flow ducts, air flow distribution means, etc).
The first portion of the air flow enhances that a micro climate inside the recording medium storage enclosure is made uniform. The micro climate is a local atmospheric zone within the recording medium storage enclosure where the climate differs from the surrounding area of the recording medium storage enclosure. For example in case the humidity of the air at the first end of the recording medium storage enclosure is higher than the humidity of the air at the second end of the recording medium storage enclosure, the circulating first portion of the air flow reduces the difference in humidity of the air of the first end and the second end of the recording medium storage enclosure.
In an exit directing step c) a second portion of the air flow, which is provided in the main air direction, is directed towards the exit opening in order to provide an overpressure inside the recording medium storage enclosure adjacent to the exit opening with respect to an ambient pressure outside the recording medium storage enclosure. The second portion of the air flow further prohibits ambient air from entering the recording medium storage enclosure through the exit opening. The second portion of the air flow may affect the remaining air pressure inside recording medium enclosure away from the exit opening. The second portion of the air flow is suitably selected such that the air pressure inside recording medium enclosure away from the exit opening is decreased little, in order that not too much air is sucked in the recording medium storage enclosure at a position away from the exit opening.
As a result the air conditions inside the enclosure are equalized (i.e. an uniform microclimate is provided) while at the same time ambient air conditions are kept outside of the enclosure. As a result of the uniform microclimate inside the recording medium storage enclosure a gradient in humidity within the paper may also be reduced by the present method leading to a reduction of cockling of the paper.
In an embodiment of the method, step a) further comprises aligning the main air flow direction along a feed path of the recording medium, which feed path is configured for conveying the recording medium towards the exit opening. A leading edge of the recording medium may be retained, after termination of the print operation, in the feed path close to the exit opening. By aligning the main air flow direction of step a) along the feed path of the recording medium, the air in the feed path is circulated within the recording medium storage enclosure during step b). Furthermore, in case a leading edge of the recording medium is present in the feed path, the conditioning of the leading end portion of the recording medium is optimized and the leading end portion is protected from ambient air conditions. A feed path may comprise several guiding plates for conveying the recording medium towards the exit opening. The main air flow direction may be aligned with a surface of one of the guiding plates.
In an embodiment of the method, the first portion of the air flow of step b) is larger than the second portion of the air flow of step c). The circulating first portion provides an uniform microclimate and the exit directed second portion provides an overpressure adjacent to the exit opening with respect to an ambient pressure outside the recording medium storage enclosure. The first portion being larger than the second portion provides that an uniform microclimate can be attained faster. The exit opening may be suitably configured, such that a second portion of the air flow is sufficient to prohibit ambient air from entering the recording medium storage enclosure through the exit opening.
In an embodiment of the method, the air of the air flow provided in step a) is pre-heated above ambient air temperature prior to step a). Pre-heated air inside the recording medium storage enclosure provides that an overall air pressure inside the recording medium storage enclosure adjacent to the exit opening increases, thereby even further prohibiting ambient air from entering the recording medium storage enclosure through the exit opening. Furthermore the pre-heated air reduces a humidity of a recording medium during circulation step b). In case a leading edge has been exposed to humid ambient air outside of the recording medium storage enclosure, a resulting gradient in humidity within the recording medium is reduced faster during conditioning inside the recording medium storage enclosure.
In an embodiment of the method, the air of the air flow provided in step a) is dehumidified with respect to an ambient air humidity prior to step a). The dehumidified air reduces a humidity of a recording medium during circulation step b). In case a leading edge has been exposed to humid ambient air outside of the recording medium storage enclosure, a resulting gradient in humidity within the recording medium is reduced faster during conditioning inside the recording medium storage enclosure.
In an embodiment of the method, the method further comprises step d) feeding a portion of the recording medium through the exit opening of the recording medium storage enclosure towards the print station of the printing system, and wherein step a) is performed after step d) has ended. A tendency of the recording medium to cockle is further reduced, in case the air flow is provided during a retraction movement of the leading edge into the recording medium storage enclosure and in case the air flow is provided during a first period directly after a termination of the print operation.
In another aspect of the present invention a printing system is provided, which comprises a printing station and a recording medium storage enclosure, wherein the recording medium storage enclosure comprises:
In an embodiment of the printing system, the air flow manifold is arranged for aligning the main air flow direction along a feed path configured for conveying the recording medium towards the exit opening. By aligning the main air flow direction of step a) along the feed path of the recording medium, the air in the feed path is circulated within the recording medium storage enclosure during step b).
In an embodiment of the printing system, the printing system further comprises a sensor for sensing an ambient air condition and wherein the control unit controls the air flow source based on a sensor signal provided by the sensor to the control unit indicating the ambient air condition. This improves the conditioning of the recording medium storage enclosure. For example a flow rate of the air flow may be adapted based on one or more of the conditions of an ambient air pressure and a humidity of the ambient air.
In an embodiment of the printing system, the recording medium storage enclosure further comprises a duct arranged for channeling the air flow from the second end of the recording medium storage enclosure towards the air flow manifold. This supports the circulating step b). The duct may be connected to the air flow manifold and may be connected to the air flow source. The duct may be a channel, may be a tube, may be a hollow cylinder and may be any other means for channeling the air flow from the second end of the recording medium storage enclosure towards the air flow manifold.
In an embodiment of the printing system, the recording medium storage enclosure further comprises a recording medium supporting means for supporting the recording medium, being arranged between the first end and the second end of the recording medium storage enclosure. The recording medium supporting means may be suitably arranged inside the recording medium storage enclosure in order to support the circulating step b).
In an embodiment of the printing system, recording medium storage enclosure further comprises a feed control system for in operation feeding a portion of the recording medium in the recording medium storage enclosure towards the printing station of the printing system, and wherein the control unit controls the air flow source based on the feeding operation by the feed control system. A reduction of the recording medium to cockle is further optimized, in case the air flow is provided based on the feeding operation by the feed control system. For example during a retraction movement of the leading edge into the recording medium storage enclosure and in case the air flow is provided during a first period directly after a termination of the feeding operation.
In another aspect of the present invention an air flow kit is provided for conditioning a recording medium storage enclosure, the recording medium storage enclosure comprising an exit opening for releasing a portion of a recording medium towards the printing station of the printing system, wherein the air flow kit comprises:
The air flow kit may be suitably arranged inside a recording medium storage enclosure in order to provide a method for conditioning the recording medium storage enclosure according to the present invention. The air flow source is arranged in the circulating air flow path between the first end and the second end of the recording medium storage enclosure.
The air flow manifold is arranged close to the exit opening, wherein the arrangement is suitable to direct the air flow in a main air flow direction adjacent to the exit opening. The distribution means is arranged along the main air flow direction close to the exit opening. The distribution means may be arranged at any position with respect to the exit opening along the main air flow path; for example preceding the exit opening, next to the exit opening or subsequently to the exit opening in the main air flow direction. The distribution means may be connected to the air flow manifold.
The duct is arranged between the second end and the air flow manifold at the first end of the recording medium storage enclosure. The duct may be connected to the air flow manifold and may be connected to the air flow source.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description.
Hereinafter, the present invention is further elucidated with reference to the appended drawings showing non-limiting embodiments and wherein
The present invention will now be described with reference to the accompanying drawings, wherein the same reference numerals have been used to identify the same or similar elements throughout the several views.
As is shown in
The paper storage unit 11 comprises one recording medium storage enclosure 12, accommodating a reel 32 and two larger recording medium storage enclosures 13 for accommodating two reels 32, each reel providing a supply of printing paper in the form of a paper roll 33. In each recording medium storage enclosure a web 34 is drawn-off from each paper roll 33 by means of an associated pair of transport rollers 36. Each of the recording medium storage enclosures 12, 13 comprises narrow feed paths 40, which merge into a common transport path 42 on the top side of the paper storage unit 11. The pairs of transport rollers 36 are selectively driven to feed the web 34 from a selected one of the reels 32 in one of the recording medium storage enclosures 12,13 to the common transport path 42. It will be understood that the reels 32 may contain paper of different qualities and possibly also non-paper recording media such as plastic films or the like. Further, the webs on the reels 32 may differ in width, so that printed sheets may be produced in different formats, ranging for example from A4 portrait to A0 landscape. With the phrase “endless web 34” it is meant that the length of paper on reels 32 is long compared to the cutted sizes A4 or A0. Typically the length of such a web is between 20 and 200 meters but can be also longer than that.
From the common transport path 42, the selected web is guided past a cutting mechanism 44 for cutting the web to the desired sheet length.
On its way from the reel 32 to the sheet support plate 20, the web 34 and the sheet 16, respectively, will be exposed to ambient air and, as a result, will absorb humidity, especially when the relative humidity RH of the ambient air is high.
When the humidity content of the paper increases, it tends to expand. Typically, the paper expands in the direction transverse to the longitudinal direction of the web. When the sheet 16, after having expanded in this way, reaches the sheet support plate 20, part of the water contained in the paper will be evaporated, and the paper shrinks again in width direction of the sheet. Thus, since a humidity gradient is present in the paper, the accompanying expansion in width of the sheet leads to the production of cockles.
The feed control system 46 is also connected to a humidity sensor 48. Further, the feed control system 46 is connected to a separating mechanism 49 (
On the other hand, if no new print job is in the print queue, the leading edge 35 of the web may be retained in the paper feed path 40 near the exit opening 60 of the recording medium storage enclosure. However ambient air is able to enter the recording medium storage enclosure 12 through the exit opening 60 as is indicated by arrow A. As a result a gradient of humidity may develop in the recording medium storage enclosure between a first end 12a of the recording medium storage enclosure, where the exit opening 60 is arranged, and a second end 12b of the recording medium storage enclosure. This causes the leading edge 35 of the web, being arranged in the paper feed path 40, to be exposed to a relatively high humidity and a peripheral surface of the roll 33b to be exposed to a relatively low humidity.
Alternatively, in case the feed control system 46 reads the air humidity that has been detected by the sensor 48, and if the air humidity is above a certain threshold level, the reel 32 is driven in reverse direction, as is indicated by an arrow Rr in
Also when the entire length of the web 34 is stored in a compacted state in the roll 33, a gradient of humidity inside the recording medium storage enclosure may grow, which causes a portion 33a of the peripheral surface of the roll, being arranged near the first end 12a of the recording medium storage enclosure, to be exposed to a relatively high humidity and a portion 33b of the peripheral surface of the roll to be exposed to a relatively low humidity.
Furthermore when a new print job is entered, the printer is again switched into the printing operating mode, and the feed control system 46 controls the reel 32 to rotate in feed direction, as has been indicated by an arrow Sr. Simultaneously, the separating mechanism 49 is activated so as to separate the leading edge of the web from the periphery of the roll 33, e.g. by air suction. The separation of the leading edge from the periphery of the roll 33 requires time and the feeding of the leading edge towards the exit opening 60 of the recording medium storage enclosure is delayed.
In the recording medium storage enclosure 12 an air flow manifold 54 is arranged at the first end of the recording medium storage enclosure 12a. The air flow manifold 54 is operatively connected to a duct 58, which is operatively connected to an air flow source 56. The air flow source 56 is controlled by a control unit 2 (shown in
The first portion F1 of the air flow provides that a micro climate, which is inside the recording medium storage enclosure 12, is made uniform. In case the humidity of the air at the first end of the recording medium storage enclosure 12a is higher than the humidity of the air at the second end 12b of the recording medium storage enclosure, the circulating first portion F1 of the air flow reduces a difference in humidity of the air between the first end and the second end of the recording medium storage enclosure. As a result a leading edge 35 of the web, which is arranged inside the paper feed path 40 close to the first end 12a of the recording medium storage enclosure, will have a similar humidity compared to a peripheral surface portion 33b of the roll, which is arranged close to the second end 12b of the recording medium storage enclosure.
The first air flow source 356 and the second air flow source 366 are controlled by a control unit (not shown). In operation condition the first and second air flow source 356, 366 provide an air flow P1, P2 along the duct 358, 368 towards the air flow manifold 354, 364, respectively. The first and second air flow manifold 354, 364 are configured to provide an air flow in a first and second main air flow direction M1, M2, respectively, adjacent to the exit opening 60. The first and second main air flow direction M1, M2 are both aligned substantially perpendicular to the feeding direction S of the web 34 through the exit opening 60. The first main air flow direction M1 is arranged substantially opposite to the second main air flow direction M2, such that two main air flow directions encounter each other adjacent to the exit opening 60. Due to the interaction between the first and the second main air flow direction M1, M2, a first circulating portion D1, E1 of each of the air flows M1, M2 is directed towards the second end of the recording medium storage enclosure 312b. Likewise a second portion D2, E2 of each of the air flows M1, M2 is directed towards the exit opening 60. The second portion D2, E2 provides an overpressure inside the recording medium storage enclosure 312 adjacent to the exit opening 60 with respect to an ambient pressure outside the recording medium storage enclosure. The ratio between the volume of each of the first portions D1, E1 and each of the second portions D2, E2 may suitably be adjusted, e.g. by adjusting the attributes of the first and second main air flow direction M1, M2.
The first and second air flow sources 456, 466 are controlled by a control unit 2 (shown in
The first air flow source 556 and the second air flow source 566 are controlled by a control unit (not shown). In operation condition the first and second air flow source 556, 566 provide an air flow P1, P2 along the duct 556, 566 towards the air flow manifold 545, 565, respectively. The first and second air flow manifold 545, 565 are configured to direct the air flow in a first and second main air flow direction M1, M2 adjacent to the exit opening 94, wherein the main air flow direction M1, M2 are both aligned substantially perpendicular to the feeding direction S of an upper cut sheet 83a through the exit opening 94. Each of the main air flow directions M1, M2 is aligned with a surface of the upper cut sheet 83a.
The first main air flow direction M1 is arranged opposite to the second main air flow direction M2, such that two main air flow directions encounter each other adjacent to the exit opening 94.
Due to the interaction between the first and the second main air flow direction M1, M2, a first circulating portion D1, E1 of each of the air flows M1, M2 is directed towards the second end 80b of the recording medium storage enclosure. Likewise a second portion D2, E2 of each of the air flows M1, M2 is directed towards the exit opening 94. The second portion D2, E2 provides an overpressure inside the recording medium storage enclosure 12 adjacent to the exit opening 94 with respect to an ambient pressure outside the recording medium storage enclosure. The ratio between the volume of each of the first portions D1, E1 and each of the second portions D2, E2 may suitably be adjusted, e.g. by adjusting the attributes of the first and second main air flow direction M1, M2.
In step S2 of the method it is judged whether a print operation is terminated. In case yes in step S4 a feed operation of the web is ended and the leading edge is retracted to the feed path 40 in the recording medium storage enclosure. In step S6 at least one attribute of the ambient air condition is determined, such as an ambient air pressure, an ambient air humidity and an ambient air temperature. The ambient air condition may be obtained from a sensor, such as humidity sensor 48. In step S8 a volume of a first circulating portion and a second portion is determined by a control unit based on the determined ambient air condition of step S6. In step S10 an air flow source is operated by the control unit in order to provide an air flow based on the volume of the first and second portion determined in step S8. In step S12 it is judged whether the ambient air humidity is high with respect to a threshold value, based on a determined ambient air condition of step S6. In case yes, in step S14 the air flow, which is provided by the air flow source inside the recording medium storage enclosure, is pre-heated or dehumidified. In step S16 the air flow is provided, inside the recording medium storage enclosure, wherein a first portion of the air flow is circulated and a second portion of the air flow is directed to the exit opening of the recording medium storage enclosure. Optionally, in case desired, a ratio between the volume of the first portion and the second portion may be adjusted in an additional step (not shown in
Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. In particular, features presented and described in separate dependent claims may be applied in combination and any advantageous combination of such claims is herewith disclosed.
Further, the terms and phrases used herein are not intended to be limiting; but rather, to provide an understandable description of the invention. The terms “a” or “an”, as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and/or having, as used herein, are defined as comprising (i.e., open language). The term coupled, as used herein, is defined as connected, although not necessarily directly.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 12170130.4 | May 2012 | EP | regional |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2013/060734 | May 2013 | US |
| Child | 14541994 | US |
