Patent Description:
In apparatuses and methods for coating a web, the web to be coated is guided by means of a web coating apparatus. For instance, the web may be guided past one or more deposition sources for depositing one or more layers of deposition material on the web. Under process conditions with high coating temperatures, however, some regions of the web may heat up excessively. Since in a vacuum environment cooling of the web by convection or radiation is strongly impaired, at high deposition rates, the web may be heated up to impermissible temperature values and thus be damaged or may even melt.

To overcome this situation, it is known that the drum supporting the web is cooled, wherein a high heat transfer coefficient (HTC) is supposed to be used. However, this represents a considerable restriction to the regular coating operation.

<CIT> discloses a roller device for use in a web coating process under vacuum conditions having a temperature adjusting system, a rotatable curved surface facing the web, and gas outlets for releasing a gas flow into voids between points of contact between the web and the curved surface.

<CIT> discloses a temperature control roller for a coating process in which a liquid-cooled roller guides a substrate. Heat transfer between the substrate and the roller surface is enhanced by introducing a gas into the space between them.

Accordingly, it would be beneficial to improve the cooling mechanism of a drum device for guiding a web in a web coating process under vacuum conditions while allowing for improved working conditions, such as cleaning efficiency, while the web is subject to fewer restrictions regarding the materials used.

This disclosure uses terms whose meaning is briefly explained here.

A drum as referred to herein may be a device which is rotationally symmetric about a rotation axis. The drum may be cylindrical or concave-cylindrical. The drum may also be a cone or a truncated cone. Typically, the drum is rotatable about the rotation axis. In some embodiments, the drum may include a stationary inner part and a rotary outer part, which rotates about the inner stationary part. Alternatively, the inner part can rotate with the outer part.

The terms axis and axial refer to a rotation axis of a rotatable element, especially of a drum. An axial direction refers to a direction parallel to the rotation axis. An axial extension of an element refers to the extension of the element along the rotation axis. The term radial refers to a direction perpendicular to the rotation axis.

A web as used within the embodiments described herein can typically be viewed as a flexible substrate characterized in that it is bendable. The term "web" may be synonymously used with the term "strip" or the term "flexible substrate". For example, the web, as described in embodiments herein, may be a foil, a plastic film or another flexible substrate.

The terms "inner area" and "outer area" refer to spaces that are complementary to each other. The term "outer area" refers to a space that is further away from the rotation axis of the drum in relation to a drum surface or a web than a space designated as "inner area".

The term "deposition device" may synonymously be used as "vapor deposition unit" or "evaporator unit" herein and may be understood as a device in a process used to turn a source material into the gaseous form of the source material, i.e. vapor. The source material can be turned first into a fluid form by a melting process and then turned into the gaseous form, or can be directly turned into the gaseous form.

The term "substantially" as used herein typically implies that there is a certain deviation, e.g. up to <NUM>%, up to <NUM>% or up to <NUM>%, from the characteristic denoted with "substantially".

According to an aspect of the present disclosure, a drum device for guiding a web in a web coating process under vacuum conditions is provided. The drum device includes a rotatable drum with a web facing surface comprising a first web facing surface portion, and a gas distribution system for providing a gas flow including a gas composition into an interspace between the web and the first web facing surface portion denoted as a first interspace, the gas composition comprising a gas and/or a vapor of a liquid. The drum device further includes a temperature adjusting system adapted for controlling the temperature of the first web facing surface portion, such that the gas composition is cooled in a manner that the gas and/or the liquid changes the aggregate state, thus forming a non-gaseous cushion in the first interspace.

According to another aspect of the present disclosure, a web coating apparatus including a vacuum chamber and a deposition device is provided. The vacuum chamber includes the drum device. The deposition device is adapted for performing chemical vapor deposition, physical vapor deposition such as evaporation or sputtering, or plasma enhanced chemical vapor deposition.

According to another aspect of the present disclosure, a method for controlling the temperature of a web in a web coating process under vacuum conditions is provided. The method includes a) moving the web over a rotatable drum with a web facing surface comprising a first web facing surface portion, b) providing a gas flow including a gas composition into an interspace between the web and the first web facing surface portion denoted as a first interspace, the gas composition comprising a gas and/or a vapor of a liquid, and c) controlling the temperature of the gas composition in the first interspace such that the gas composition is cooled in a manner that the gas and/or the liquid changes the aggregate state, thus forming a non-gaseous cushion in the first interspace.

According to another aspect of the present disclosure, a method for coating a web under vacuum conditions is provided. The method includes controlling the temperature of the web as described herein; and depositing coating material on the web by chemical vapor deposition, physical vapor deposition such as evaporation or sputtering, or plasma enhanced chemical vapor deposition.

According to another aspect of the present disclosure, a controller is provided that includes a processor and a memory storing instructions that, when executed by the processor, cause a web coating apparatus to perform a method as described herein.

The drum device, the coating apparatus and the method for controlling temperature provide an improved concept for guiding a web in a web coating process under vacuum conditions, and allow for efficiently cooling the web during the coating process. The improved cooling efficiency impairs neither the cleaning efficiency of the drum, nor the use of a large diversity of web materials including webs with large thickness and/or low temperature stability.

Further aspects, advantages and features of the present disclosure are apparent from the dependent claims, the description and the accompanying drawings.

So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the present disclosure, briefly summarized above, may be had by reference to typical embodiments. The accompanying drawings relate to embodiments of the present disclosure and are described in the following:.

Reference will now be made in detail to the various embodiments of the present disclosure, one or more examples of which are illustrated in the figures. Within the following description of the drawings, the same reference numbers refer to the same components. Generally, only the differences with respect to individual embodiments are described. Each example is provided by way of explanation and is not meant as a limitation of the present disclosure. Features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the description includes such modifications and variations.

<FIG> show schematic views of an exemplary embodiment of a drum device for guiding a web in a web coating process under vacuum conditions. <FIG> shows a schematic view of an exemplary embodiment of a web coating apparatus. Details explained with illustrative reference to <FIG> shall not be understood as limited to the elements of <FIG>. Rather, those details may also be combined with further embodiments explained with illustrative reference to the other figures.

<FIG> is focused on the geometrical structure of the drum device <NUM> independently from a deposition process, whereas <FIG> show the drum device <NUM> during operation, i.e. during a deposition process.

The drum device <NUM> shown in <FIG> may include a rotatable drum <NUM> with a web facing surface <NUM> comprising a first web facing surface portion <NUM>. A drum <NUM> as referred to herein may be a device which is rotationally symmetric about a rotation axis <NUM>. The drum <NUM> may be cylindrical or concave-cylindrical. The drum <NUM> may also be a cone or a truncated cone. Typically, the drum <NUM> is rotatable about the rotation axis <NUM>. In some embodiments, the drum <NUM> may include a stationary inner part <NUM> and a rotary outer part, which rotates about the inner stationary part <NUM>. Alternatively, the inner part can rotate with the outer part.

The web facing surface or region <NUM> may be seen as a part or region of the drum surface that faces and/or guides the web <NUM>. From the perspective of an observer along the rotation axis <NUM> of the drum <NUM>, the web facing surface <NUM> can be viewed with an angular opening <NUM> that encloses the web facing surface <NUM> (see <FIG>). That means, the web facing surface <NUM> may extend along said angular opening <NUM>.

The drum device <NUM> as described herein may further include a gas distribution system <NUM> for providing a gas flow <NUM> including a gas composition into an interspace between the web <NUM> and the first web facing surface portion <NUM>. The interspace is denoted as a first interspace <NUM>. The gas composition includes a gas and/or a vapor of a liquid.

The first web facing surface portion or region <NUM> may be seen as a part or region of the drum web facing surface <NUM>, where the first web facing surface portion <NUM> and the facing area of the web <NUM> define or form a receiving volume or first interspace <NUM> that receives the gas flow <NUM>. From the perspective of an observer along the rotation axis <NUM> of the drum <NUM>, the first web facing surface portion <NUM> is viewed with an angular opening <NUM> encompassing the first web facing surface portion <NUM> (see <FIG>).

The angular extension of the first web facing surface portion <NUM> is preferably less than the angular extension of the web facing surface <NUM>.

The axial extensions of the web facing surface <NUM> and of the first web facing surface portion <NUM> are substantially the same. Axially, the web facing surface <NUM> may extend along a span that i) encompasses the width of the web <NUM>, and/or ii) is shorter or at most the same length as the axial extension of the drum <NUM>.

In rotation direction <NUM> of the drum <NUM>, the first web facing surface portion <NUM> is followed by a region of the drum surface termed second web facing surface portion <NUM>. From the perspective of an observer along the rotation axis <NUM> of the drum <NUM>, the second web facing surface can be viewed with an angular opening <NUM> that encloses the second web facing surface (see <FIG>). That means, the second web facing surface may extend along said angular opening <NUM>. An interspace between the web <NUM> and the second web facing surface portion <NUM> is denoted as a second interspace <NUM>. Advantageously, the non-gaseous cushion <NUM> transforms within the second interspace <NUM> into a gas cushion <NUM> designed to cool the web <NUM> when heat is applied from outside the drum <NUM>.

The drum device <NUM> as described herein may further include a temperature adjusting system <NUM> adapted for controlling the temperature of the first web facing surface portion <NUM> such that the gas composition is cooled in a manner that the gas and/or the liquid changes the aggregate state within the first interspace <NUM>, thus forming a non-gaseous cushion or medium <NUM>, in the first interspace <NUM>. In particular, the temperature adjusting system may be configured to cool at least parts of the drum, in particular the first web facing surface portion.

The non-gaseous cushion <NUM> within the first interspace <NUM> may be a solid or fluid cushion. The non-gaseous cushion <NUM> may extend at most to an angular edge and/or axial edge of the first web facing surface portion <NUM>.

The liquid or solid cushion <NUM> allows the cooling medium to be transported to the interspace adjacent to the deposition area <NUM>, i.e. the process area, without escaping during transportation. In contrast thereto, by use of a gas cushion, the gas stays trapped only shortly. The gas converted into a fluid or solid state however cannot escape and may efficiently be transported to the process area, in which it may change back to the gaseous state, due to the high temperature, and can provide a high heat transfer coefficient in the process area.

The web coating apparatus <NUM> shown in <FIG> may include a vacuum chamber <NUM> and a deposition device <NUM>, the vacuum chamber <NUM> including the drum device <NUM>. The deposition device <NUM> may be adapted for performing chemical vapor deposition, physical vapor deposition such as evaporation or sputtering, or plasma enhanced chemical vapor deposition.

The deposition device <NUM> may vaporize a source material and the vapor <NUM> generated may be forwarded to the web <NUM>. After passing the shields <NUM>, or rather the window formed by the shields <NUM>, the vapor <NUM> may be deposited on the web <NUM>. Especially in the area where material of the deposition vapor <NUM> is deposited on the web <NUM>, a considerable amount of heat is applied to the web <NUM>. It is therefore essential to ensure effective cooling of the web <NUM> in the deposition area <NUM>. This is enabled by the gas cushion <NUM> within the second interspace <NUM> below the deposition area <NUM> of the web <NUM>, the gas cushion <NUM> thus acting as a cooling cushion.

The deposition device <NUM> may transfer the material to be deposited onto the web <NUM> in a deposition area <NUM> of the web <NUM> which is adjacent to the second interspace <NUM>. As a consequence of the heating related to the deposition process, the non-gaseous cushion <NUM> inside the first interspace <NUM> transforms into a gas cushion <NUM> inside the second interspace <NUM>.

Drum devices wherein a gas cushion is formed in an interspace between web and drum regularly suffer from the problem that the gas does not remain in the interspace but instead dissipates out of the interspace. The gas remaining in the interspace is insufficient in quantity and is no longer able to achieve a sufficient cooling effect to the web. Thus, during the coating of the web, when heat is applied, the web may be damaged. In addition, also the drum may be contaminated, which is particularly bad if the drum has openings or pores that may get clogged.

The described obstacles are overcome by the concept of the present drum device <NUM>, wherein a non-gaseous cushion <NUM> is built up inside the first interspace <NUM>. The material of the non-gaseous cushion <NUM> inside first interspace <NUM> either does not escape from the first interspace <NUM> at all or at least to a much lesser extent. This causes a sufficient amount of gas to be left in the second interspace <NUM>, allowing for a gas cushion <NUM> within the second interspace <NUM> providing improved cooling of the deposition area <NUM> of the web <NUM> onto which material is deposited in the deposition process.

The improved cooling enables the use of a wide range of web materials, including materials with a low thermal stability and/or temperature-sensitive web materials. Advantageously, due to the improved cooling, neither the HTC, nor the thickness of the web or of the deposition layer play a limiting role in the selection of the parameters of the coated web. In this way, a thick layer can also be deposited on the web <NUM>, for example <NUM>, which is known to be <NUM> times thicker than classic layers for packaging with aluminum or copper.

With the present concept, damage to the web <NUM> due to insufficient cooling is substantially less probable, which also enables easy and efficient cleaning of the drum <NUM>.

According to embodiments that can be combined with any other embodiments described herein, the temperature adjusting system <NUM> may be adapted for changing, in the first interspace <NUM>, the aggregate state of the liquid to the solid state by freezing. Additionally or alternatively, the temperature adjusting system <NUM> may be adapted for changing, in the first interspace <NUM>, the aggregate state of the gas to the solid state, especially by deposition. Additionally or alternatively, the temperature adjusting system <NUM> may be adapted for changing, in the first interspace <NUM>, the aggregate state of the gas to the liquid state. When changing the aggregate state of the liquid or of the gas to the solid state, a solid cushion <NUM> may be created in the first interspace <NUM>. When changing the aggregate state of the gas to the liquid state, a liquid cushion <NUM> may be created in the first interspace <NUM>. The solid cushion shows even less dissipation than a liquid cushion, which in turn shows much less dissipation than a gaseous cushion.

According to embodiments that can be combined with any other embodiments described herein, no continuous layer or cushion is formed in the first interspace <NUM>. Instead, the frozen vapor may fill the pores of the web <NUM> and/or surface of the drum <NUM>. Thus, the gas composition may be trapped as frozen vapor and cannot escape such as in the known devices. Once the frozen vapor has melted, in a region following the second interspace <NUM> in the rotation direction <NUM>, the gas composition may escape and may subsequently be pumped out.

In this document, the term "cushion" includes a gas composition being i) formed as a layer of frozen vapor or gas between drum surface <NUM> and web <NUM>, and/or ii) deposited or trapped as frozen vapor or gas in the pores of the web <NUM> and/or drum surface <NUM>.

The amount of material remaining in the solid cushion <NUM> within the first interspace <NUM> is large enough to allow a sufficient amount of material in the gas cushion <NUM> within the second interspace <NUM>, thus enabling effective cooling of the web <NUM> in the region suffering from the heating related to the deposition process.

According to embodiments that can be combined with any other embodiments described herein, the temperature adjusting system <NUM> may be adapted for controlling the temperature of the gas flow <NUM> entering the first interspace <NUM>. A control in the sense of heating the gas flow <NUM> may result in that the gas can be injected at high pressure without any state transition occurring before the gas has entered the first interspace <NUM>. A control in the sense of cooling the injected gas flow <NUM> may result in a lower cooling requirement to achieve a solid gas cushion <NUM> within the first interspace <NUM>.

According to embodiments that can be combined with any other embodiments described herein, the temperature adjusting system <NUM> may include a temperature sensing unit <NUM> adapted to measure the temperature of the gas composition and/or of the first web facing surface portion <NUM>. The sensing unit may be, for example, an IR sensor located in an inner area of the drum <NUM>.

According to embodiments that can be combined with any other embodiments described herein, the temperature adjusting system may include a temperature adjusting unit <NUM> adapted to adjust the temperature of the gas composition and/or of the first web facing surface portion <NUM>. The temperature adjusting unit <NUM> may be based on liquid cooling, the drum <NUM> being provided with an array of passages around the drum perimeter.

According to embodiments that can be combined with any other embodiments described herein, the temperature adjusting system <NUM> may include a controller <NUM> connectable or connected to the temperature sensing unit <NUM> and/or the temperature adjusting unit <NUM>. The controller <NUM> may be adapted to control the temperature of the gas composition within a predetermined temperature range. Compared to direct temperature actuation, the present control system can work more efficiently and save energy.

The controller may furthermore be configured to control the method for coating a web as described herein. The controller <NUM> may include a central processing unit (CPU), a memory and, for example, support circuits. To facilitate control of the temperature adjusting system, the CPU may be one of any form of general-purpose computer processor that can be used in an industrial setting for controlling various chambers and sub-processors. The memory is coupled to the CPU. The memory, or a computer readable medium, may be one or more readily available memory devices such as random access memory, read only memory, USB stick, hard disk, or any other form of digital storage either local or remote. The support circuits may be coupled to the CPU for supporting the processor in a conventional manner. These circuits include cache, power supplies, clock circuits, input/output circuitry and related subsystems, and the like. The software routine may also be stored and/or executed by a second CPU (not shown) that is remotely located from the hardware being controlled by the CPU. The software routine, when executed by the CPU, transforms the general-purpose computer into a specific purpose computer (controller) that controls the temperature adjustment. Although the method and/or process of the present disclosure is discussed as being implemented as a software routine, some of the method actions that are disclosed therein may be performed in hardware as well as by the software controller. As such, the invention may be implemented in software as executed upon a computer system, and in hardware as an application specific integrated circuit or other type of hardware implementation, or a combination of software and hardware.

According to embodiments that can be combined with any other embodiments described herein, the liquid may include at least one of a group including:.

Especially water and/or glycerol transform fast from gas to solid phase when hitting the coating drum, at a given temperature and pressure, thus being very well suited.

According to embodiments that can be combined with any other embodiments described herein, the gas may include at least one of a group including:.

Especially gases with high momentum transfer (when masses are equal) are highly suitable.

According to embodiments that can be combined with any other embodiments described herein, the drum device <NUM> may include shields <NUM> located close to the web <NUM> in an outer area of the web <NUM>. At least one shield may be located on each side of the second web facing surface portion <NUM>, to define a window responsible for the passage of coating material to the web section vis-à-vis the second web facing surface portion <NUM>. The shields <NUM> allow a desired and precisely defined amount of deposition material to be deposited through the window onto the web <NUM>, which is advantageous in ensuring a desired and/or constant thickness of the layer deposited on the web <NUM>. In addition, the shields <NUM> prevent heating of the web <NUM> outside the section vis-a-vis of the second web facing surface portion <NUM>, which ensures that the gas cushion <NUM> in the second interspace <NUM> contains an amount of gas that is constant over time, thus preventing fluctuations in the cooling effect.

According to embodiments that can be combined with any other embodiments described herein, the gas distribution system <NUM> may include at least one nozzle <NUM>-<NUM> for providing a directed and/or metered supply of gas flow <NUM> into the first interspace <NUM>. A "nozzle" as referred to herein may be understood as a device for guiding a gas, especially for controlling the direction or characteristics of the gas (such as the rate of flow, speed, shape, and/or the pressure of the gas that emerges from the nozzle). The nozzle may have an inlet for receiving the gas, a passage or channel for guiding the gas through the nozzle, and an outlet for releasing the gas. According to embodiments described herein, the channel of the nozzle may include a defined geometry for achieving the direction or characteristic of the gas flowing through the nozzle. According to some embodiments, a nozzle may be part of a distribution assembly, e.g. a distribution pipe or one or more point sources. Additionally or alternatively, a nozzle as described herein may be connectable or connected to the distribution assembly providing gas and may receive gas from the distribution assembly.

According to embodiments that can be combined with any other embodiments described herein, at least one nozzle, in the following denoted as t-nozzle <NUM>, may be adapted for providing the gas flow <NUM> into the first interspace <NUM> tangentially or substantially tangentially with respect to the drum <NUM>, i.e. to the drum surface.

According to an embodiment, the t-nozzle <NUM> may have a linear slot-shaped outlet adapted to inject the gas flow <NUM> into a feed zone or gap leading into the first interspace <NUM> and extending over at least part of the width of the web <NUM>, preferably over the entire width of the web <NUM>. The feed zone is formed when the web <NUM> is rolled onto the drum <NUM>, at the entrance of the first interspace <NUM>. A nozzle as described herein, and especially the t-nozzle <NUM> can be an air blade configured to provide a homogeneous gas jet into the infeed edge. The air blade may extend approximately over the entire first web facing portion.

According to another embodiment, the t-nozzle <NUM> may have a plurality of circular outlets arranged linearly side by side to provide a homogeneous or substantially homogeneous gas jet into the feed zone.

The t-nozzle <NUM> may be positioned at the beginning of the first interspace <NUM> with respect to the rotation direction <NUM> of the drum <NUM>.

The linear slot-shaped outlet or the linear arrangement of circular outlets may be aligned parallel to the feed zone and located at a short distance from the feed zone. The two t-nozzle embodiments described above may be implemented separately or in combination with each other.

<FIG> shows a schematic view of a drum device <NUM> for guiding a web <NUM> in a web coating process under vacuum conditions. Details explained with illustrative reference to <FIG> shall not be understood as limited to the elements of <FIG>. Rather, those details may also be combined with further embodiments explained with illustrative reference to the other figures.

According to embodiments described herein, the gas distribution system <NUM> may comprise at least one nozzle, in the following denoted as r-nozzle <NUM>, <NUM>, of which the outlet is disposed in the drum surface and adapted for providing the gas flow <NUM> into the first interspace <NUM> radially or substantially radially with respect to the drum <NUM> or the drum surface. The embodiment of <FIG> is focused on the design and function of r-nozzles within the drum device <NUM> alternatively to t-nozzles shown in <FIG>. However, the features already explained with reference to <FIG>, even not shown with all details in <FIG> for the sake of clarity, may be combined with the features explained with reference to <FIG>.

The r-nozzles <NUM>, <NUM> may be adapted to release gas from the gas distribution system <NUM> in a direction substantially perpendicular to the drum surface at positions where the respective r-nozzle <NUM>, <NUM> is located. In the example shown in <FIG>, the r-nozzles <NUM>, <NUM> are distributed over the surface of the drum <NUM>. In particular, the r-nozzles <NUM>, <NUM> are distributed in a regular manner over the surface of the drum <NUM>.

The feature "disposed in a regular manner" may imply that the distance of a first r-nozzle and at least one neighbor r-nozzle of the first r-nozzle is substantially identical to the distance of a second r-nozzle with respect to at least one neighbor of the second r-nozzle. In some embodiments, the feature "disposed in a regular manner" may refer to a surface wherein a specific pattern can be assigned to a portion of the multitude of r-nozzles and the same pattern can be assigned to another portion of the multitude of r-nozzles. In some embodiments, the r-nozzles may be disposed in an irregular manner over the circumference of the drum <NUM>.

According to embodiments which can be combined with any other embodiments described herein, any nozzle outlet can be selected from the group consisting of: openings, holes, slits, blast pipes, spray valves, duct openings, orifices, jets, outlets provided by a porous material and the like. According to some embodiments, a nozzle outlet as referred to herein may have any suitable shape, such as substantially round, circular, elliptic, triangular, rectangular, quadratic, a polygon, an irregular shape, such as an irregular round shape, an irregular angled shape, a shape being different from one gas outlet to the other, or the like. According to some embodiments, the r-nozzle outlets do not protrude out of the drum surface.

According to embodiments which can be combined with any other embodiments described herein, a gas source <NUM> may be provided. The gas source <NUM> may be part of the distribution system <NUM>, as shown in <FIG>, or of the web coating apparatus <NUM> according to <FIG>, in which the gas source is not shown.

According to embodiments which can be combined with any other embodiments described herein, the r-nozzles may comprise a first subgroup of r-nozzles <NUM> consisting of at least one r-nozzle of which the outlet is in the first web facing surface portion <NUM> and a second subgroup of r-nozzles <NUM> consisting of at least one r-nozzle of which the outlet is outside the first web facing surface portion <NUM>.

According to embodiments which can be combined with any other embodiments described herein, the gas distribution system <NUM> may be configured for providing the gas flow <NUM> to the first subgroup of r-nozzles <NUM> and for preventing the gas from flowing to the second subgroup of r-nozzles <NUM>.

The gas distribution system <NUM> may allow for selectively providing a gas flow <NUM> to the first subgroup of the r-nozzles <NUM>. The r-nozzles <NUM> that are (temporarily) located in the first web facing surface portion <NUM> belong to the first subgroup of the r-nozzles <NUM>.

During operation, the membership of any single r-nozzle to the first or second subgroup may change. In other words, an open r-nozzle may be closed at a later time and vice versa. In some embodiments, membership of the gas outlets to the first and/or second subgroup is changed during operation dependent on the rotational position of the drum surface. The first web facing surface portion <NUM> may remain at a fixed position in space, and gas r-nozzles entering the first web facing surface portion <NUM> due to the rotation of the drum surface are opened (or connected to the gas source <NUM>), i.e., the membership is changed to the first subgroup. R-nozzles leaving the first web facing surface portion <NUM> due to the rotation of the drum surface are closed (or disconnected from the gas source <NUM>), i.e., the membership is changed to the second subgroup.

The gas distribution system <NUM> of the drum <NUM> according to some embodiments described herein may be adapted to selectively provide and prevent gas flow in defined r-nozzles by the size, location, shape and construction, kinetic properties of the gas distribution system <NUM> and the like. For instance, in the example of <FIG>, the gas distribution system <NUM> may include a gas source <NUM> arranged in or presenting a stationary part <NUM> of the drum <NUM>. The gas source <NUM> may have a size encompassing a section of the circumference of the stationary part <NUM> of the drum <NUM>. The drum surface may rotate about the rotation axis <NUM> of the drum <NUM> and, in particular, about the stationary part <NUM> of the drum <NUM> (including e.g. the gas source <NUM>).

According to some embodiments described herein, the gas channels of the r-nozzles leading from the gas source <NUM> to the first subgroup of r-nozzles <NUM> when the respective r-nozzle is in the first web facing surface portion <NUM> may be conducting. The gas channels lead from the gas source <NUM> to the second subgroup of r-nozzles when the respective r-nozzle is outside the first web facing surface portion <NUM> may be non-conducting. The gas distribution system <NUM> with a gas source <NUM> and gas channels may be described as being partially rotary (e.g. the gas channels) and partly stationary (e.g. the gas source <NUM>). With the gas channels rotating about the gas source <NUM>, the gas distribution system <NUM> allows to selectively connect and disconnect the gas channels to the gas source <NUM>.

According to some embodiments, the gas distribution system <NUM>, and in particular the gas source <NUM> provides a gas flow <NUM> to the r-nozzles <NUM> (as exemplarily shown by two arrows in <FIG>). In some embodiments, the gas flow <NUM> provided by the gas distribution system <NUM> to the r-nozzles <NUM> is a gas flow <NUM> still allowing the web <NUM> to be in contact (at least in punctual contact) with the drum surface. For instance, the gas flow <NUM> may typically be between about <NUM> sccm and about 400sccm, more typically between about <NUM> sccm and about <NUM> sccm, and even more typically between about <NUM> sccm and about <NUM> sccm.

The gas distribution system <NUM> according to embodiments described herein may be adapted to provide a flow rate of the gas per area of the drum surface typically between about <NUM> sccm/m2 and about <NUM> sccm/ m2, more typically between about <NUM> sccm/ m2 and about <NUM> sccm/ m2, and even more typically between about <NUM> sccm/ m2 and about <NUM> sccm/ m2. In one example, the gas distribution system <NUM> may be adapted to provide a flow rate of the gas per area of the drum surface which may typically be about <NUM> sccm/ m2.

According to some embodiments, which may be combined with other embodiments described herein, the gas distribution system <NUM> may be adapted to provide a defined gas flow rate by one or more parameter, such as for instance number or size of the r-nozzles, fluid conductance of the gas distribution system <NUM>, size or capacity of the gas source <NUM>, size and power of a pumping system for the gas, size and design of gas channels, and/or the like.

According to some embodiments, which may be combined with other embodiments described herein, the number of r-nozzles may typically be between <NUM> and <NUM>, more typically between <NUM> and <NUM>, and even more typically between <NUM> and <NUM>, in particular for a drum device <NUM> with gas channels (as exemplarily shown in <FIG>). According to some embodiments, the drum surface may be partitioned into gas sections. In some embodiments, each gas section has several r-nozzles. In some embodiments, the number of r-nozzles in the first web facing surface portion <NUM> may be between <NUM> and <NUM>.

According to some embodiments, which may be combined with other embodiments described herein, an r-nozzle may have a cross-section size of typically between about <NUM> and about <NUM>. The cross-section size may be measured as the minimum cross-section of the r-nozzles at the drum surface. In some embodiments, the fluid conductance of the r-nozzles may typically be between about <NUM> liter/sec and about <NUM> liter/sec, more typically between about <NUM> liter/sec and about <NUM> liter/sec, and even more typically between about <NUM> liter/sec and about <NUM> liter/sec. In one embodiment, the fluid conductance of the r-nozzles may be about <NUM> liter/sec.

According to some embodiments, which may be combined with other embodiments described herein, the drum device <NUM> may include a driving unit <NUM> for rotating the drum <NUM> and/or smaller deflection drums <NUM>. The drum <NUM> may guide the web <NUM> in cooperation with the deflection drums <NUM>, with the deflection drums ensuring sufficient web <NUM> tension and improved guiding behavior.

<FIG> shows a schematic view of a method for controlling the temperature of a web <NUM> in a web coating process under vacuum conditions. Details explained with illustrative reference to <FIG> shall not be understood as limited to the elements of <FIG>. Rather, those details may also be combined with further embodiments explained with illustrative reference to the other figures.

The method <NUM> for controlling the temperature of a web <NUM> in a web coating process under vacuum conditions may include:.

<FIG> shows a schematic view of a method for coating a web <NUM> in a coating process under vacuum conditions. Details explained with illustrative reference to <FIG> shall not be understood as limited to the elements of <FIG>. Rather, those details may also be combined with further embodiments explained with illustrative reference to the other figures.

The method <NUM> for coating a web <NUM> in a coating process under vacuum conditions may include:.

Claim 1:
A drum device (<NUM>) for guiding a web (<NUM>) in a web coating process under vacuum conditions, comprising:
- a rotatable drum (<NUM>) with a web facing surface (<NUM>) comprising a first web facing surface portion (<NUM>);
- a gas distribution system (<NUM>) for providing a gas flow (<NUM>) including a gas composition into an interspace between the web (<NUM>) and the first web facing surface portion (<NUM>) denoted as a first interspace (<NUM>), the gas composition comprising a gas and/or a vapor of a liquid; and
- a temperature adjusting system (<NUM>) adapted for controlling the temperature of the first web facing surface portion (<NUM>) such that the gas composition is cooled in a manner that the gas and/or the liquid changes the aggregate state, thus forming a non-gaseous cushion (<NUM>) in the first interspace (<NUM>).