EP1559835B1 - Apparatus and process for applying on both sides of a substrate a fluid or pasty medium with at least one coater on a traveling paper web, in particular of paper or cardboard, as well as a process useful in connection therewith for determining of surface related separate coatings - Google Patents

Abstract

The web coating applicator station (12) has applicators (12a,12b) flanking a moving web (10), of paper or cardboard, to apply a liquid or paste coating on both sides of it. Sensors (14,16) are linked to a decision unit (20,22) which determines the coating volume to be used to cover the web surfaces, using the differences in their signals for web gloss and/or whiteness. A delegation unit (K) gives the values to spread an even coating on both sides of the web.

Description

The invention relates, in one aspect, to a machine for application of a liquid or pasty application medium on both sides of a moving material web, in particular of paper or cardboard, with a sensor arrangement which responds to the total area-related application of application medium on both sides of the material web or / and at least one size dependent on the area-related total order of application medium on both sides of the material web.

Such machines are known in many forms. It is particularly thought of so-called coating machines for the online painting or the offline coating of paper or cardboard on both sides, namely to such machines in which both sides are deleted simultaneously or quasi-simultaneously or immediately or in quick succession. It is particularly thought of such cases in which the web side has not dried before the other web page is deleted. For example, the machine may be equipped with a film press coater which simultaneously applies to both sides of the web. However, it is also possible to provide coating units such as curtain applicators, spray applicators or so-called blade or blade applicators or applicators with corresponding doctor devices, which apply in each case only to one side of the material web. As mentioned, in this context, above all, such an embodiment is thought that no drying between the line on one side and the line on the other side is provided. It Can be applied from the outset in a set dosage, as is usually the curtain application, or it can be applied in excess, with subsequent leveling and dosing by means of a squeegee device of the commissioned work.

In order to achieve a high and uniform coating quality, the coating weight on each side must be determined or at least taken into account when painting on both sides. There are line weight sensors that can reflectively measure the line weight for a web side according to a near-infrared absorption method. However, such sensors must be calibrated cumbersome and have not proven to be sufficiently accurate. In contrast, the total line weight, that is, the sum of the individual line weights on both web pages, can be easily measured by means of known basis weight sensors by measured before application, the basis weight of the uncoated web and after application to both sides of the material web weight of the coated web coated on both sides becomes. The difference between these basis weights gives the total line weight. Surface weight sensors have proven useful, which determine the weight per unit area from the extinction of the radiation of a radioactive source, usually a β radiation source, of known intensity by the material web according to a radioactive measuring method. However, it is also possible to use optical sensors which measure the degree of transmission or absorption of the material web.

The US B1-6,171,642 discloses an operating method and a device for direct or indirect application of a liquid to pasty application medium on a moving material web, in particular of paper or cardboard, wherein the material web is coated with a layer of the application medium by means of a commissioned work and the widening result then by means of a measuring sensor for deviations from investigated in the event of such deviations either corrective measures or a warning is issued to the operating personnel visually or acoustically.

From the DE 102 53 822 A1 a method and an apparatus for automatic sensor calibration is known, which in the manufacture of a fibrous web, in particular a paper or board web, to measure parameters needed for the manufacturing process. To correct the on-line measurement performed by a sensor, a laboratory measurement is performed based on a liquid sample from a hydrogen sulfide suspension filled with a valve, the result obtained in the laboratory measurement being used to determine the sensor whose measurement result deviates from the actual measured value. to be calibrated by means of an automatic procedure called online calibration.

The EP-A-0 829 575 discloses a method and a device for direct or indirect application of a liquid or pasty medium on a moving material web, in particular of paper or cardboard, wherein during the application, the cross profile of the medium is influenced controlled and in the direction of flow thereafter affects the longitudinal profile of the previously applied medium controlled becomes. The control of the cross profile and the control of the longitudinal profile of the applied medium are carried out separately from each other in automatic control circuits due to measurements of the applied profile. Fig. 3 discloses in addition an arrangement which is suitable for two-sided coating of a material web, in which case the medium is first applied by two separate applicators on the lateral surfaces of two applicator rolls, after which the medium applied by the respective applicator medium with the rotation of the applicator roll first Egalisierungsseinrichtung happens before the medium then passes with the further rotation of the applicator roll in an order gap, where the medium is transferred to the moving web, which is passed through the nip.

The US-A-6,132,805 discloses a method for applying a liquid or pasty medium directly or indirectly to a moving material web, in particular of paper or cardboard, by means of an applicator with an applicator, a doctor element and a doctor element holder on which the doctor element is held. Furthermore, measuring stations are provided which supply values to a computing unit via the transverse and / or longitudinal profile of the uncoated material web and the coated material web in order to set a nozzle gap width of the application device in accordance with the acquired measurement results.

An object of the invention is to allow the double-sided brushing a consideration of the line weight per web page (generally the surface-related single job on the respective web page) based on the total recorded line weight (generally the area-related total order of application medium on both sides of the web).

To solve this problem, the invention proposes according to an aspect related to the above-mentioned machine that this one at the Sensor arrangement having connected determination device which receives at least one of the area-related total order of application medium on both sides of the web or the size dependent or reflecting or indicative output from the sensor array and based on this issue and a distribution ratio of the area-related total order on the two sides of the Material web representing division value determines the area-related individual orders of application medium for both sides of the web.

In this context, the invention further provides a method for determining area-related individual orders of application medium in two-sided application of a liquid or pasty application medium by means of at least one commissioned work on a moving material web, in particular of paper or cardboard, in which at least one area-related total order of application medium receive both sides of the web or a dependent size representing or reflecting or indicating output from a sensor array and based on this output and a division ratio of the area-related total order on the two sides of the web representing distribution value determines the area-related individual orders of application medium for both sides of the web becomes.

According to the proposal of the invention, the measurement of the area-related individual order, ie about the line weight per web page, by means of special sensors, such as the mentioned infrared reflection sensors dispensable and the associated, complex calibration can be omitted. It is possible to realize, for example, a line weight control per material web page from the measurement results for the overall line and the determined individual line weights or the line weight difference between the two sides. The line weight per material web page (in general, the area-related individual order of application medium per material web page) can enter, for example, as an actual value in the control of the page-related stroke order, together with a page-related target value and / or a target value for the overall stroke.

In particular, a mathematical division of the surface-related overall order received on the application medium (of the overall line) onto the two material web pages is considered according to the distribution relation given by the division value. The division relation or the division value can be predetermined quantities, resulting for example from a calibration or adjustment of the line distribution at the beginning of the application, or - preferably - quantities resulting from additional measurements on the moving material web.

The division value may be a quantity that indicates the distribution ratio of the area-related total order, which in this case is a distribution ratio, on the two sides of the material web in the sense of a quotient formation. The splitting value can then be conveniently called a splitting factor. However, the distribution value can also indicate the division of the area-related total order on the two sides of the material web in the sense of a difference and then expediently be referred to as a distribution difference value or distribution difference.

It is preferably contemplated that the sensor arrangement comprises at least one of the sides of the material web associated sensor which responds to the surface-related single order of application medium on the associated side of the web or / and on at least one surface-related individual order of application medium on the associated side of the Material web dependent property of the material web. It is particularly preferred that the sensor arrangement in assignment to both sides of the material web in each case has at least one sensor which responds to the area-related individual order of application medium on the associated side of the material web and / or on at least one surface-related individual order of application medium on the associated side of the Material web dependent property of the material web. It is especially thought that this sensor or these sensors do not respond directly to the area-related individual order, but on a dependent, In contrast, easier and more reliable measurable size.

In a further development, it is proposed that the determination device or a further determination device of the control device receive the area-related individual order of application medium on the side of the material web assigned to the sensor or the size dependent on it, reflecting or indicating further output from the sensor arrangement and on the basis of this output the sensor Distribution ratio of the area-related total order on the two sides of the material web representing distribution value determined. With regard to the method, it is proposed in this context that at least one further output representing the area-related individual order of application medium on one side of the material web or a size dependent thereon or received or reproduced from the sensor arrangement receive and on the basis of this output the distribution relation of the area-related overall order the two sides of the material web representing distribution value is determined.

As already indicated, the machine can advantageously comprise at least one control device comprising the determining device which receives the output from the sensor arrangement representative of the area-related overall order of application medium on both sides of the material web or the size dependent thereon, and on the basis of this output the area-related total order of application medium on both sides of the web by driving the at least one applicator at least a predetermined or predetermined total target. Further, it is proposed that the at least one applicator for each side of the web permits an individual adjustment of the area-specific order to order medium or that the two sides of the web in each case at least one own, the individual setting of the area-related individual order of application medium for the respective side of the material permitting Commissioned work is assigned, and that the Control device in association with the two sides of the web in each case comprises at least one controller, based on the determined by the determining unit area-related individual order for the respective side of the web by controlling the applicator or the page assigned applicator individually the surface-related single order to order medium a predetermined or predeterminable respective individual target at least approximates.

According to another aspect, the invention relates to a machine for two-sided application of a liquid or pasty application medium by means of at least one commissioned work on a moving material web, in particular of paper or cardboard, with a sensor arrangement responsive to the area-related total order of application medium on both sides of the web or / and at least one size dependent on the area-related overall order of the application medium on both sides of the material web, and with at least one control device having at least one output representing the surface-related total order of application medium on both sides of the material web or the size dependent thereon or reflecting Sensor arrangement receives and based on this edition the area-related total order of application medium on both sides of the web by controlling the at least one applicator a predetermined or vorg At least approximates the overall target.

According to the invention, it is proposed for this machine according to the invention that the at least one applicator permits individual adjustment of the surface-related individual application to application medium or that the two sides of the material web each have at least one own individual adjustment of the surface-related individual application to application medium the respective side of the material web permitting commissioned work is assigned, that the sensor arrangement has at least one of the sides of the material web associated sensor, which responds to the area-related single order of application medium on the associated side of the Material web and / or on at least one of the area-related order to order medium on the associated side of the material web dependent property of the material web, and that the control device at least one surface-related single order to order medium on the sensor associated side of the web or the dependent property representing or reflecting or indicative of further output from the sensor array receives and based on this output in combination with the area-related total order of application medium on both sides of the web or the size dependent or reflecting or indicating output by driving the applicator or the commissioned works for both sides Material web individually individually the area-related single job to order medium at least a predetermined or predetermined individual target.

In this context, the invention further provides a method for two-sided application of a liquid or pasty application medium by means of at least one commissioned work on a moving web, in particular of paper or cardboard, in which at least one area-related total order of application medium on both sides of the web or a From this dependent output size representative or reflecting or indicating output received by a sensor array and based on this edition of the area-related total order of application medium on both sides of the web by driving the at least one applicator a predetermined or predetermined total target is at least approximated. According to the invention, it is proposed that at least one further output representing the area-related individual order to application medium on one side of the material web or a property dependent thereon be received by the sensor arrangement and based on this output in combination with the area-related total order of application medium on both sides the material web or the size dependent on this or reflecting or indicating output by controlling the applicator or commissioned works for both sides of the Material web each individually the area-related individual order to order medium a predetermined or predetermined individual target is at least approximated.

According to the invention, a regulation of the area-related individual order of application medium (possibly the line weight per page) is possible on the basis of the area-related total order of application medium on both sides, possibly of the total line measured by conventional means, in combination with the output of at least one further sensor. which responds to the area-related individual order to application medium on the associated side of the web or / and on at least one of the area-related single job order medium on the associated side of the material web dependent property of the web and provides a corresponding output.

In principle, it is possible to use a dedicated line-weight sensor which measures the line weight in a reflective manner, for example in the infrared absorption method. You could possibly make do with a single sensor that determines the stroke weight only for one web page. Compared to the design of the machine with two line weight sensors, which are each assigned to a material web side, there would be the advantage that only one sensor is to calibrate. The individual line for the other material web side could then be determined from the total line determined on the basis of the measurement results of the sensor arrangement and the single line measured for one side. In contrast, however, it is preferred that the sensor responds to a surface-related individual order of application medium on the associated side of the material web-dependent property of the material web, which is easier to measure than the coating weight itself. For example, it is intended to measure the whiteness, gloss or color of the web.

With regard to the machine according to the invention, it is proposed that the sensor arrangement in association with both sides of the material web has in each case at least one sensor which responds to the surface-related one Individual order to application medium on the associated side of the web or / and on at least one of the area-related single order to order medium on the associated side of the material web dependent property of the web.

The control device may advantageously comprise a determination device which receives the at least one output representing the area-related total order of application medium on the two sides of the material web or the size dependent or reflecting from the sensor arrangement and on the basis of this output and a distribution relation of the area-related total order on the two sides of the material web representing distribution value determined the area-related individual orders of application medium for both sides of the web. Regarding the method, it is proposed in this context that based on the at least one output of the sensor arrangement and a distribution relation of the area-related total order on the two sides, the at least one total order of order medium on both sides of the web or the size dependent thereon the material web representing division value the area-related individual orders are determined on application medium for both sides of the web.

The distribution value may again be a distribution factor in the sense of a quotient indicating a "distribution factor", or a "distribution difference" indicating the division of the area-related total order on the two sides of the material web in the sense of a difference. With regard to a distribution value or "distribution factor" which indicates the distribution ratio in the sense of a quotient, the option is also considered that the allocation ratio is kept constant in the event of a change in the area-related overall order to the two sides in the course of the order. This possibility or proposal relates both to intended and also intrinsically unintentional changes in the area-related total order on the two sides of the web.

According to an embodiment of the control device which is preferred in this context, the control device comprises, in association with the two sides of the material web, at least one controller which, on the basis of the surface-related individual application determined by the determination unit, for the respective side of the material web by controlling the applicator or the side assigned to it Order work individually the surface-related individual order to order medium to the predetermined or specifiable respective individual target at least approximates. Regarding the method is proposed in this context that for both sides of the web on the basis of the specific area-specific order for the respective page by driving the order or the page assigned to the order individually the area-related single order to order medium the predetermined or predetermined individual target is at least approximated.

The split value may be predetermined, for example, due to a calibration or adjustment at the beginning of the job. In contrast, in the case of the machine according to the invention, however, it is preferred that the determination device or a further determination device of the control device receives the surface-related individual application to the application medium on the side of the material web assigned to the sensor or the variable representing or reflecting or indicating it from the sensor arrangement, and on the basis of this output, determines the distribution value representing the distribution ratio of the area-related total order on the two sides of the material web. For the inventive method is proposed in this context, that on the basis of the surface-related individual order to order medium on the side of the material web or the size dependent on or reflecting or indicating further output of the Distribution ratio of the area-related total order on the two sides of the material web representing distribution value is determined.

The machine can be designed so that the respective individual target for the area-related individual order to the application medium can be specified or predefined for both sides of the material web. In this context, it is proposed for the method according to the invention that the respective individual target for the area-related individual order is applied to the application medium for both sides of the material web.

In this connection, it is particularly thought in relation to the machine that the actuation of the applicator or of the two web pages associated applicators by the two controllers to approximate the area-related individual orders of application medium to the predetermined or specifiable respective individual target, the approximation of the area-related total order on application medium on both sides of the material web to the sum of the individual target corresponding total target results. Accordingly, in the process implementation, the control of the commissioned work or the two web pages associated applicators to approximate the area-related individual orders of application medium to the predetermined or specifiable individual target, the approximation of the area-related total order of application medium on both sides of the web to which the sum of Individual target corresponding total target result. An additional regulation to approximate the area-related total order to the total target is thus unnecessary. In particular, it is then not necessary to specify an overall target in addition to the individual target values, since this results directly from the individual target values, namely in particular their sum.

Another possibility is that the machine is designed so that the total target for the area-related individual order to order medium is predetermined or can be specified. Regarding the procedure one can Accordingly, provide that the total target for the area-related individual order is given to order medium.

Concerning the machine, in this context, it is proposed that the or a determination device of the control device determines the respective individual target for the area-related individual order of application medium on the basis of one or the distribution value representing a target distribution relation of the area-related total order on the two sides of the material web. Accordingly, in the method, the respective individual target for the area-related individual order to order medium can be determined on the basis of or a division value representing the target distribution ratio of the area-related total order on the two sides of the material web.

In this context, it is primarily thought that the distribution value (possibly distribution factor or distribution difference) representing the desired distribution ratio is predetermined or can be predetermined or predetermined by the distribution value to be distinguished from the determined distributional value (determined in particular by the determination device) ,

An expedient design of the machine is characterized in that with respect to at least one side of the material web for at least one of the area-related order to order medium dependent property of the material web to which the (respective) side of the material web associated sensor responds, a desired property or at least one desired relation to another property of the material web is predetermined or predefinable. It is especially thought that with respect to both sides of the web for at least one of the area-related single order application medium on the respective side dependent property of the web to which responds to the respective side of the web associated sensor, a desired property or at least one Target relation to another property of the material web or a desired relation between the area-related individual order Order medium dependent property with respect to the one side of the material web and the surface-related individual order to application medium dependent property with respect to the other side of the material web is predetermined or predetermined.

With regard to the method according to the invention, it is accordingly proposed that with respect to at least one side of the material web for at least one of the area-related individual order of application medium dependent property of the material web to which at least one respective side of the material web associated sensor of the sensor arrangement responds, a desired property or at least one desired relation to another property of the material web is specified. It is especially thought that with respect to both sides of the web for at least one of the area-related single order application medium on the respective side dependent property of the web to which at least one of the respective side of the material web associated sensor responds, a desired property or at least one desired relation to another property of the material web or a desired relation between the property dependent on the area-related individual order to application medium with respect to the one side of the material web and the property dependent on the area-related individual order to application medium with respect to the other side of the material web is given.

One possibility for the design of the control device in this context is that this comprises in association with the two sides of the material web in each case at least one controller based on the predetermined desired property or desired relation and the area-related individual order to order medium respective side of Material web or the further property representing or reflecting or indicating further output by triggering the applicator or the applicator assigned to the page with respect to the surface-related individual order to application medium the property of the predetermined or specifiable desired property or a fulfillment detected by the respective sensor of the at least approximates predetermined or predefinable setpoint relation. For the inventive method is proposed in this context that based on the predetermined desired property or target relation and the area-related individual order to order medium of the relevant side of the web or the property dependent on this or reflecting or indicating further output by controlling the applicator or of the commissioned work associated with the page in relation to the area-related individual order to order medium, the property of the predetermined or specifiable desired property or a fulfillment of the predetermined or predefinable desired relation detected by the respective sensor is at least approximated.

According to another expedient embodiment of the control device, this has in association with both sides of the material web at least a first and at least a second controller, which together or directly control the commissioned work or commissioned works. It is provided that the first controller on the basis of the total target for the area-specific order to order medium and the area-related total order to order medium on both sides of the web or the size dependent on or reflect or give output at least one approximation of the area-related total order Application medium on both sides of the material web to the predetermined or predetermined total target provides and that the second controller based on the desired property or desired properties or desired relation or desired relations and the area-related order single application medium of the relevant side of the web or the further output representing or reflecting or indicating this is at least an approximation of the property detected by the at least one sensor or the sensors to the predetermined or predefinable desired characteristic aft or to a fulfillment of the predetermined or specifiable setpoint relation provides. In this context, it is particularly preferred that the control device comprises a drive device, which is based on at least a first Control output (possibly command variable) of the first controller and at least a second control output (possibly reference variable) of the second controller controls the commissioned work or the commissioned works in the sense of a division of one provided by the first control output (reference variable), referring to both sides of the web Total order on two individual orders relating only to one side of the material web in accordance with the second standard edition (reference variable).

For the inventive method is proposed in this context that based on the total target for the area-specific order to order medium and the area-related total order to order medium on both sides of the web or the size dependent on or reflect or reflect or output at least an approximation of area-related total order of application medium on both sides of the web to the predetermined or specifiable total target is effected by outputting at least a first control output (possibly reference variable) and at the same time on the basis of the desired property or desired properties or setpoint relation or setpoint relations and at least one approximation by the little related to the surface-related individual order to order medium of the relevant side of the web or the further output representing or reflecting or indicating thereof Stens a sensor or the sensors detected property to the predetermined or specifiable target property or to a fulfillment of the predetermined or predetermined desired relation is effected by issuing at least one second control output (possibly Reference variable). In this context, it is primarily thought that based on the first control output and the second control output, the commissioned work or the commissioned works are / are controlled in the sense of a division of one provided by the first control output, to both Pages of the material web related total order on two only on one side of the material web related individual orders in accordance with the second rule edition.

It has been suggested that the sensor arrangement may comprise at least two basis weight sensors. It is especially contemplated in this regard that of the basis weight sensors of at least one, the basis weight of the web prior to application and at least one other the basis weight of the web after application to both sides, and that one of the determination means is adapted to the area weights before and after application to determine the area-related total order of application medium on both sides of the web, in particular the total weight. Accordingly, the method may comprise the step of determining the area-related overall order of application medium on both sides of the material web, in particular the total line weight, from the basis weights before and after application.

Furthermore, as has already been mentioned, the sensor arrangement in association with at least one of the sides of the material web, preferably in association with both sides of the material web (respectively) at least one in particular optically reflective on the area-related individual order of application medium on the associated side of the material web and / or on at least one of surface-related individual order to order medium on the associated side of the material web-dependent property of the material web responsive sensor, in particular gloss sensor or color sensor or white sensor include.

According to a preferred embodiment of the machine, the determination device may be designed to determine a relation, in particular a difference or ratio, between a property of the material web dependent on the surface-related individual application to application medium on this side of the material web Material representing web size and related to the other side of the web, depending on the area-related order to order medium on this side of the web dependent property of Determine material web representing sizes, optionally a white ratio or gloss ratio or a white difference or gloss difference. For the method according to the invention, it is proposed in this connection that a relation, in particular a difference or a ratio, between a quantity which relates to the one side of the material web and the property of the material web that depends on the area-related individual application to application medium on this side of the material web a reference to the other side of the web, which is determined by the area-related order to order medium on this side of the web dependent property of the web representing size, optionally a whiteness ratio or gloss ratio or a white difference or gloss difference.

With regard to the regulation, it is particularly preferable for a set value-actual-value comparison for the line weight to be carried out separately for each page. A deviation between the desired value and the actual value can serve as an input variable for a conventional control variable to be adjusted conventionally, for example by an operator, such as contact pressure, pumping quantity, flow rate. Preference is given to automated regulation, so that the desired coating weight is set automatically for each side.

Fig. 1

zeigt ein Beispiel für die seitenbezogene Strichgewichtsermittlung auf Grundlage eines Aufteilungs- oder Splitwerts.

Fig. 2

zeigt in Kombination mit Fig. 3a ein erstes Ausführungsbeispiel sowie in Kombination mit Fig. 3b ein zweites Ausführungsbeispiel für eine seitenbezogene Strichgewichtsregelung auf Grundlage des Aufteilungs- oder Splitwerts.

Fig. 3

zeigt in der Teilfigur 3a die seitenbezogene Strichgewichtsregelung auf Grundlage eines ermittelten Ist-Einzel-Strichgewichts für die jeweilige Materialbahnseite sowie auf Grundlage eines Soll-Gesamtstrichs und in Teilfigur 3b die seitenbezogene Strichgewichtsregelung auf Grundlage eines ermittelten Ist-Einzel-Strichgewichts für die jeweilige Materialbahnseite sowie auf Grundlage eines jeweiligen Soll-Einzel-Strichgewichts.

Fig. 4

zeigt schematisch eine Möglichkeit, wie der Aufteilungs- oder Splitwert durch Messungen an der beidseitig gestrichenen Materialbahn bestimmt werden kann, und zwar beim Ausführungsbeispiel speziell auf Grundlage einer Glanz-Differenz.

Fig. 5

zeigt eine Abwandlung der Bestimmung des Aufteilungs- oder Splitwerts auf Grundlage einer normierten Glanz-Differenz anstelle einer unnormierten Glanz-Differenz.

Fig. 6

dient zur Veranschaulichung von Verallgemeinerungen gegenüber den Bestimmungen des Aufteilungs- oder Splitwerts gemäß Fig. 4 oder 5, bei der allgemein auf Grundlage von Messergebnissen an den beiden gestrichenen Materialbahnseiten und Relationen zwischen diesen der Aufteilungs- oder Splitwert bestimmt wird.

Fig. 7

zeigt ein weiteres Beispiel für eine seitenbezogene Strichgewichtsregelung auf Grundlage eines gemessenen Gesamtstrichs und weiteren, an beiden Seiten der gestrichenen Materialbahn gemessenen Materialbahneigenschaften.

The invention will be explained in more detail below with reference to embodiments shown in the figures.

Fig. 1

shows an example of the page-based bar weight determination based on a split or split value.

Fig. 2

shows in combination with Fig. 3a a first embodiment and in combination with Fig. 3b A second embodiment of a page-based bar weight control based on the division or split value.

Fig. 3

shows in the sub-figure 3a, the page-based bar weight control based on a determined actual single-line weight for the respective material web page and on the basis of a target overall stroke and in part 3b, the page-based bar weight control based on a determined actual single line weight for the respective material web page and on Basis of a respective nominal single line weight.

Fig. 4

shows schematically a way in which the division or split value can be determined by measurements on the material web coated on both sides, specifically in the exemplary embodiment based on a gloss difference.

Fig. 5

Figure 12 shows a modification of the determination of the split or split value based on a normalized gloss difference instead of an unnormalized gloss difference.

Fig. 6

As an illustration, generalizations to the provisions of the split or split value are given in accordance with Fig. 4 or 5 in which the division or split value is generally determined on the basis of measurement results on the two coated material web pages and relations between them.

Fig. 7

shows another example of a page-based bar weight control based on a measured total bar and further, measured on both sides of the coated material web material properties.

According to Fig. 1 a paper web 10 is coated on both sides with application medium 11o or 11u, in particular coating color. The application takes place by means of an applicator 12 acting on both material web sides or alternatively by means of two applicators 12a and 12b assigned in each case to one material web side. The Coating amount to the respective material web side can be regulated by suitable adjustment parameters, for example via a doctor pressure P or a pumping quantity Q.

By means of two basis weight sensors 14 and 16, which detect the basis weight, for example, by the extinction of radioactive radiation in transmission through the material web, the total coating amount on both sides of the web, namely the so-called total line weight, can be determined. For this purpose, in the running direction L of the material web, in particular paper web or board web, the first sensor 14 in front of the commissioned work 12 or the commissioned works 12a, 12b and the second sensor 16 after the commissioned work 12 or the commissioned works 12a, 12b. The first sensor detects the basis weight M _raw in the raw state, ie in the non-coated state of the material web, and the second sensor detects the total basis weight M _{tot of} the material web in the coated and preferably already dried state. From the raw basis weight and the total basis weight, the total coating quantity, ie the total bar Ms, can be determined by forming the difference. The total line M _S can be determined by a determination unit 20 of signals from the two sensors. This total line Ms corresponds to the sum of the present coating quantities (line weights) M _{S, O} for the material web top side and M _{S, U} for the material web underside, which are not directly detectable by the sensors 14 and 16.

From the total line Ms thus determined, a further determination unit 22 determines the individual line weights M _{S, O} and M _{S, U} , based on a division or split value K, which is predetermined, for example stored in a memory unit 24, or by a determination unit 26 determining the split or split value is provided. The reference numerals 24 and 26 are to be understood as alternatives in this respect.

The division or split factor K, hereinafter referred to as the split factor K for short without limiting the generality, can be used in the calculation of the Individual order quantities, in particular individual line weights, take into account any asymmetrical division. As far as the split factor is not specified, for example based on a calibration or at the beginning of correct stroke distribution, the split factor can be useful via a correlation with other paper data, eg. Paper gloss or paper whiteness.

To represent the Fig. 1 is still nachzutragen that two dashed lines are to symbolize S that between the applicator 12 and the commissioned works 12a and 12b and the total basis weight after application detected sensor 16 quite a greater distance or a larger, of the material web 10 zurückzulegende Guide track can be provided. For example, the web could pass through a drying assembly before reaching the sensor 16.

Based on the according to Fig. 1 certain individual line weights can advantageously be a regulation of the applied by the commissioned work 12 and the commissioned works 12a and 12b single-line weight for both material web pages. Fig. 2 shows in combination with Fig. 3a a first embodiment and in combination with Fig. 3b a second embodiment of such a weight control. The labels B1 and B2 and A1 and A2 indicate the relationship between the Fig. 2 and the Fig. 3a or the relationship between the Fig. 2 and the Fig. 3b and may, for example, be regarded as designations of terminals or the like.

According to Fig. 3a is a total line weight M _{S, should be} specified. A storage unit storing this desired value is designated 30. By means of a determination unit 32, a target line weight value M _{S, O, soll} for the upper material web side and M _{S, U, soll} for the lower material web side is determined from the total desired value for both material web sides, in accordance with a split or split value K, also referred to below without restriction of generality as a split factor K. It is quite possible that it is the same division or split value K, which is the Determining the individual line weights M _{S, O} and M _{S, U} , the actual values on which the determination unit 22 is based. In contrast, it is preferred that in the determination by the determination unit 32 certain division of the total setpoint M _{S, should} in the individual setpoints M _{S, O, should} and M _{S, U, soll} by the determination unit 32, another distribution or Split factor is received, in particular simply a predetermined desired division or split value K _soll (Soll -Splitfaktor), as in Fig. 3a additionally indicated in brackets. In this case, this setpoint value can be stored in a memory unit 34 and supplied by it to the determination unit 32.

The determination unit 32 supplies the individual setpoint values M _{S, O, soll} and M _{S, U, soll to} a control device 40 or 42 associated with the material web upper side or the material web underside, which in FIG Fig. 3a each symbolized by the comparison or difference forming member 40 and 42, respectively. The control devices or the difference-forming member receives from the determination unit 22 the upper or lower coating weight actual value M _{S, O} or M _{S, U.} An output from a respective control element reference variable X is _O or X _U is supplied to the application unit 12 and to the respective application unit 12a and 12b to approach the respective coating weight to the desired value, in particular regulate the coating weight to the desired value.

The embodiment according to Fig. 3b differs from the embodiment according to Fig. 3a in the illustrated embodiment alone in that not the total line weight M _{S, should} and an associated desired division or split value K _{should be} specified, but directly the target individual line weights M _{S, O, soll} and M _{S, U , shall} .

The page weight control can also be done as follows. The difference of the measured basis weights M _ges and M _raw gives the total line weight as the actual value, ie the total line weight, which is currently being applied. This instantaneous value is in a computer program with the desired target value M _{S, should} , ie the desired total line weight, compared. In this case, a possible deviation between the instantaneous actual value and the desired nominal value is calculated. Based on this, the deviation between the actual and desired values with respect to the material web top and the web bottom side is calculated on the basis of the split or split value K, which ensures that adjustments in the metering dosage are always in the same ratio between material web top side and bottom side Material web base are made. It can be provided that an adaptation only follows if the calculated deviation exceeds a set tolerance value.

It can be realized according to the above in a simple manner continuously from the measurement of the basis weights of the web before and after applying a control of the weights per page. In this case, by means of the division or split value K, a specific division between material web top and material web underside can be set. This also makes it possible in particular to compensate for a certain two-sidedness of the raw paper or cardboard. Additional sensors for measuring the line weight per web page are not necessary according to this approach. It is possible to work with a predetermined or pre-set division or split value K resulting from a calibration or correct setting at the beginning of the application.

A particularly preferred embodiment of the embodiments and generally the machine according to the invention or the method according to the invention, on the other hand, provides that the division or split value K, which is included in the determination of the individual line weights for the two material web pages, is itself also based on the material web after Application-related measurement results is determined. Fig. 4 shows a corresponding embodiment, in addition to Fig. 1 respectively. Fig. 2 combined with Fig. 3 is referenced. There are added to the sensors 14 and 16 additional sensors 50 and 52, with respect to both coated material web pages each having a weight-dependent material web property, such as the Gloss or the whiteness of the web, measure. The detection of such a specific material web properties of the respective material web side can be used to divide the total stroke actual value detected by the sensors 14 and 16 into the page-related individual line weights (actual values).

For example, it is possible to proceed in such a way that a deviation of the surface properties between the upper side and the lower side is compared with a currently applied division or split value. This can then be adjusted so that the deviation in the material web property between the top and bottom, such as gloss or white, is minimized or approaches a target value.

Referring to the embodiments of the Fig. 1 . Fig. 2 With Fig. 3a and Fig. 2 With Fig. 3b For example, it may be provided that the division or split value K supplied to the determination unit 22 is determined by the distribution or split value K supplied to the determination unit 22 Fig. 4 schematically shown arrangement 26 is determined. From a gloss value G _O determined by the gloss sensor 50 assigned to the upper material web side and a gloss value G _U determined by the gloss sensor 52 assigned to the lower material web side, a gloss difference ΔG (t) is determined by a difference formation unit 54. In an evaluation unit 56 receiving the gloss difference value, an instantaneous split or split value K (t) is assigned to the gloss difference value, for example on the basis of a previously stored characteristic curve or a previously stored characteristic map or on the basis of a previously stored assignment function.

Assuming that the same coating weight is provided for both material web sides and accordingly both material web sides should shine the same, a difference value ΔG> 0 results in a split or split value <1 and results in a split or split value from a difference value ΔG <0 K> first If both sides of the material web have the same gloss, then the difference value .DELTA.G = 0 and thus a division or split value K = 1 result, so that the individual line weights M _{S, O} and M _{S, U} correspond to half the total weight M _S.

It should be noted that the material web is passed after passing through the sensors 50 and 52, for example, a reel.

A variant for the division or split value determination K on the basis of gloss measurements is in Fig. 5 shown. Instead of the difference-forming unit 54, a difference-forming and normalizing unit 54 'is provided which determines a normalized difference Δ (t), which is evaluated by the unit 56' in principle in the same way as by the unit 56. to provide the current split or split value K.

For gloss measurement, it should be noted that this is prior art in itself. The same applies to a basically also possible white measurement or color measurement. In a gloss measurement, for example, by means of a reflectometer, the light reflected from the surface can be measured in terms of its intensity in an angular range bounded by diaphragms. Preferably, a plurality of, for example, three angles of incidence and thus measuring ranges are used in order to eliminate or at least minimize a dependence of the reflectometer value on the angle of incidence. For example, a white measurement may be based on a comparison of the light reflection between the surface to be measured and a whiteness plate serving as a white standard. Corresponding sensors and sensor arrangements are available from various suppliers, for example ABB Automation and Lehmann Mess-Systeme AG.

Fig. 6 represents a generalization of the determination of the division or split value K based on the respective line weight-dependent properties of the material web. The material web 10 having coating application 11 _O or 11 _U on both sides passes through an upper sensor arrangement 50 'and a lower sensor arrangement 52', which provide measurement results S _{o, i} and S _{U, i} . In a Determination unit 54 "is at least one secondary size T _i from at least one of the upper material web page related measurement result S _{O, i} and at least one related to the lower material web page measurement result S _{U, i} , for example, determines a ratio, or / and at least one secondary Size O _{i, J} from at least two measurement results S _{O, i} and S _{O, j} or / and at least one secondary quantity U _{i, j} relating to the upper material _{web side} from at least two measurement results S _{U, i} and S relating to the lower material web side _{U, j} . Based on one or more of the addressed secondary variables or - alternatively - on the basis of the measurement results S _{O, i} and S _{U, i} itself determines the evaluation unit 56 "based on stored characteristic curves or maps or a stored assignment function the currently applicable Division or split value K, which then, for example, the unit 22 according to Fig. 1 or Fig. 2 is supplied.

It should also be pointed out that, based on the invention, it is advantageous to provide a given or desired division of the total line weight onto the individual line weights M _{S, O} and M _{S, U} in the sense of a given or desired division ratio M _{S, O} / M _SU keep constant or can selectively vary according to a desired course, especially in a desired or occurring change in the total line weight M _S = M _{S, O} + M _{S, U.}

Fig. 7 Figure 4 shows an overall system for page-wise bar weight control based on the total stroke detected and recorded gloss level of the coated web. For the same or analogous components with respect to the embodiment of the Fig. 7 the same reference numerals as used for the embodiments explained above, and only changes compared to the previously explained embodiments are explained. Otherwise, explicit reference is made to the comments above.

There are two again each represented by a subtraction element or comparator 60 and 62 control devices provided. The control device 60 receives the provided based on the measurement results from the sensors 14 and 16 by the difference forming unit 20 overall stroke value _S M, is compared with a predetermined desired value _{S M, is intended.} The desired value can be stored in a memory unit 64. The comparison results in a reference variable X _S relating to the total line, which is provided by a control element of the control device 60.

The control device 62 receives from the differentiating and normalizing unit 54 'the normalized gloss difference Δ, which _is compared with a predetermined desired value Δ _soll . The desired value can be stored in a memory unit 66. From the comparison results in a reference variable X _Δ , which is provided by a control element of the control device 62.

The reference variables X _S and X _Δ control the application unit 12 or the commissioned units 12 a and 12 _b via a drive device 70 with regard to the page-related coating order. For this purpose, the control device 70, a relating to the order on the upper material web page reference variable X is _O and one relating to the order on the lower material web page command value X _U ready to be supplied to the application unit or on the applicators. If one starts from a linear relationship between the respective reference variable and the resulting total line weight or single line weight (the control elements and the actuating devices of the commissioned unit or the commissioned units controlled by them can be designed accordingly without further ado), then one can provide in that the reference variables X _O and X _U which directly determine the application on the upper or lower material web side are additive or subtractive from the reference variable X _S relating to the overall order and the reference variable X relating to the division of the overall order onto the two material web _{pages Δ} .

There are still many forms of page-weighted weight control possible. For example, a zone-by-zone rule for achieving or be provided at least to approximate a desired transverse profile of the respective stroke weight. With regard to the gloss measurement, it is also possible to provide a quotient formation instead of forming a difference (normalized or unnormalized). As already on the basis of Fig. 6 addressed, one can also combine several measurements respectively for the top and the bottom of the material web, which can be used in addition to difference formations and quotient formals also other random, the measured values related functions.

The gloss measurement or whiteness measurement or other measurement with respect to the material web top and the material web underside can take place close to or at the tambour in the material web rewind station. Another possibility is a measurement online on the measuring frame, where, for example, the total basis weight M _{tot is} measured.

For a particularly fast control, one can measure the total basis weight or / and gloss or at least one other, depending on the applied application medium property directly after the commissioned work or after the commissioned works, possibly even before a drying arrangement. In this case, dependencies of the total weight per unit area M _ges or the detected side-related material web property (such as whiteness or gloss) of the moisture contained in the application medium can also be taken into account in the control.

Claims (43)

1. Machine for the application of a liquid or pasty medium by means of at least one applicator (12; 12a, 12b) to both sides of a moving web (10), in particular of paper or board,
   having a sensor arrangement (14, 16), which responds to the area-based total application of medium to both sides of the web (10) and/or to at least one variable that depends on the area-based total application of medium to both sides of the web,
   characterized by a determination device (20, 22) which is connected to the sensor arrangement, receives from the sensor arrangement (14, 16) at least one output (M_base, M_total) which represents or reflects or indicates the area-based total application of medium to both sides of the web or the variable dependent thereon and, on the basis of this output and a distribution value (K) representing a distribution relation of the area-based total application to the two sides of the web, determines the area-based individual applications (M_S,u, M_S,l) of medium for the two sides of the web.
2. Machine according to Claim 1, characterized in that the sensor arrangement (14, 16, 50, 52; 14, 16, 50', 52') has at least one sensor (50, 50; 50', 52') which is assigned to one of the sides of the web and which responds to the area-based individual application of medium to the associated side of the web and/or to at least one property of the web that depends on the area-based individual application of medium to the associated side of the web.
3. Machine according to Claim 1, characterized in that the sensor arrangement (14, 16, 50, 52; 14, 16, 50', 52') assigned to both sides of the web has in each case at least one sensor (50, 50; 50', 52') which responds to the area-based individual application of medium to the associated side of the web and/or to at least one property of the web that depends on the area-based individual application of medium to the associated side of the web.
4. Machine according to Claim 2 or 3, characterized in that the determination device or a further determination device (26) of the control device receives from the sensor arrangement the further output (G_U, G_l; S_u,1, S_l,1) which represents or reflects or indicates the area-based individual application of medium to the side of the web associated with the sensor (50; 50; 50'; 52') or the variable dependent thereon and, on the basis of this output, determines the distribution value (K) representing the distribution relation of the area-based total application to the two sides of the web.
5. Machine according to one of Claims 1 to 4, characterized by at least one control device (20, 22, 40, 42) which comprises the determination device (20, 22), receives from the sensor arrangement (14, 16) the at least one output (M_base, M_total) which represents or reflects or indicates the area-based total application of medium to both sides of the web or the variable dependent thereon and, on the basis of this output, brings the area-based total application (M_S) of medium to both sides of the web at least close to a predefined or predefinable total set point by driving the at least one applicator.
6. Machine according to Claim 5, characterized in that the at least one applicator (12) for both sides of the web permits an individual setting of the area-based individual application of medium, or in that the two sides of the web are in each case assigned at least one dedicated applicator (12a or 12b) permitting individual setting of the area-based individual application of medium for the respective side of the web, and in that the control device (20, 22, 40, 42) associated with the two sides of the web in each case comprises at least one controller (40 or 42) which, on the basis of the area-based individual application (M_S,u or M_S,l) determined by the determination unit (20, 22) for the respective side of the web, brings the area-based individual application of medium at least close to a predefined or predefinable respective individual set point individually by driving the applicator or the applicator assigned to the side.
7. Machine for the application of a liquid or pasty medium by means of at least one applicator (12; 12a, 12b) to both sides of a moving web (10), in particular of paper or board,
   having a sensor arrangement (14, 16, 50, 52; 14, 16, 50', 52'), which responds to the area-based total application of medium to both sides of the web (10) and/or to at least one variable dependent on the area-based total application of medium to both sides of the web, and having at least one control device (40, 42; 60, 62), which receives from the sensor arrangement at least one output (M_base, M_total) which represents or reflects or indicates the area-based total application of medium to both sides of the web or the variable dependent thereon and, on the basis of this output, brings the area-based total application (M_S) of medium to both sides of the web at least close to a predefined or predefinable total set point by driving the at least one applicator,
   characterized in that the at least one applicator (12) for both sides of the web permits an individual setting of the area-based individual application of medium, or in that the two sides of the web are in each case assigned at least one dedicated applicator (12a or 12b) permitting individual setting of the area-based individual application of medium for the respective side of the web,
   in that the sensor arrangement has at least one sensor (50, 52; 50', 52') which is assigned to one of the sides of the web and which responds to the area-based individual application of medium to the associated side of the web and/or to at least one property of the web that depends on the area-based individual application of medium to the associated side of the web, and
   in that the control device (40, 42; 60, 62) receives from the sensor arrangement at least one further output (G_U, G_L; S_U,1, S_L,1) which represents or reflects or indicates the area-based individual application of medium to the side of the web associated with the sensor or the property dependent thereon and, on the basis of this output, in combination with the output (M_base, M_total) which represents or reflects or indicates the area-based total application of medium to both sides of the web or the variable dependent thereon, brings the area-based individual application of medium at least close to a predefined or predefinable respective individual set point individually in each case by driving the applicator or the applicators for both sides of the web.
8. Machine according to Claim 7, characterized in that the sensor arrangement assigned to both sides of the web has in each case at least one sensor (50 or 52; 50' or 52') which responds to the area-based individual application of medium to the associated side of the web and/or to at least one property of the web that depends on the area-based individual application of medium to the associated side of the web.
9. Machine according to Claim 7 or 8, characterized in that the control device comprises a determination device (20, 22), which receives from the sensor arrangement the at least one output (M_base, M_total) which represents or reflects or indicates the area-based total application of medium to both sides of the web or the variable dependent thereon and, on the basis of this output and a distribution value (K) representing a distribution relation of the area-based total application to the two sides of the web, determines the area-based individual applications (M_S,u, M_S,l) of medium for the two sides of the web.
10. Machine according to Claim 9, characterized in that the control device associated with the two sides of the web in each case comprises at least one controller (40 or 42) which, on the basis of the area-based individual application (M_S,u or M_S,l) determined by the determination unit for the respective side of the web, brings the area-based individual application of medium at least close to the predefined or predefinable respective individual set point individually by driving the applicator or the applicator assigned to the side.
11. Machine according to Claim 9 or 10, characterized in that the determination device or a further determination device (26) of the control device receives from the sensor arrangement the further output (G_U, G_L; S_U,1, S_L,1) which represents or reflects or indicates the area-based individual application of medium to the side of the web associated with the sensor (50, 52; 50', 52') or the variable dependent thereon and, on the basis of this output, determines the distribution value (K) representing the distribution relation of the area-based total application to the two sides of the web.
12. Machine according to one of Claims 7 to 11, characterized in that, for both sides of the web, the respective individual set point (M_S,u,SP, M_S,l,SP) for the area-based individual application of medium is predefined or predefinable.
13. Machine according to Claim 12, referring back to Claim 10, characterized in that driving the applicator or the applicators assigned to the two sides of the web by means of the two controllers (40, 42) in order to bring the area-based individual applications of medium close to the predefined or predefinable respective individual set point results in the area-based total application of medium to both sides of the web coming close to the total set point corresponding to the sum of the individual set points.
14. Machine according to one of Claims 7 to 12, characterized in that the total set point (M_S,SP) for the area-based individual application of medium is predefined or predefinable.
15. Machine according to Claim 14, characterized in that the or one determination device (32) of the control device determines the respective individual set point (M_S,u,SP, M_S,l,SP) for the area-based individual application of medium on the basis of one or of the distribution value (K; K_SP) representing an intended distribution relation of the area-based total application to the two sides of the web.
16. Machine according to Claim 15, characterized in that an intended distribution value (K_SP) to be distinguished from the distribution value determined by the determination device is predefined or predefinable as the distribution value representing the intended distribution relation.
17. Machine according to one of Claims 7 to 14, characterized in that, in relation to at least one side of the web, for at least one property of the web that depends on the area-based individual application of medium and to which the sensor which is assigned to the (respective) side of the web responds, an intended property or at least one intended relation to another property of the web is predefined or predefinable.
18. Machine according to one of Claims 7 to 14, referring back to Claim 8, characterized in that, in relation to the two sides of the web, for at least one property of the web that depends on the area-based individual application of medium to the respective side and to which the sensor (50, 52) which is assigned to the respective side of the web responds, an intended property or at least one intended relation to another property of the web or an intended relation (Δ_SP) between the property that depends on the area-based individual application of medium in relation to the one side of the web and the property that depends on the area-based individual application of medium in relation to the other side of the web is predefined or predefinable.
19. Machine according to Claim 17 or 18, characterized in that the control device associated with the two sides of the web in each case comprises at least one controller which, on the basis of the predefined intended property or intended relation and the further output which represents or reflects or indicates the area-based individual application of medium to the respective side of the web or the property dependent thereon, brings the property registered by the respective sensor at least close to the predefined or predefinable intended property or to fulfilment of the predefined or predefinable intended relation by driving the applicator or the applicator assigned to the side in relation to the area-based individual application of medium.
20. Machine according to Claim 17 or 18, referring back to Claim 8, characterized in that the control device associated with the two sides of the web comprises at least one first controller (60) and at least one second controller (62) which, directly or indirectly, jointly drive the applicator (12) or the applicators (12a, 12b),
    the first controller (60) providing for the area-based total application (M_S) of medium to both sides of the web to be brought at least close to the predefined or predefinable total set point (M_S,SP) on the basis of the total set point (M_S,SP) for the area-based individual application of medium and the output (M_base, M_total) which represents or reflects or indicates the area-based total application of medium to both sides of the web or the variable dependent thereon, and the second controller (62) providing for the property registered by the at least one sensor or the sensors to be brought at least close to the predefined or predefinable intended property or to fulfilment of the predefined or predefinable intended relation (Δ_SP) on the basis of the intended property or intended properties or intended relation (Δ_SP) or intended relations and the further output (G_U, G_L) which represents or reflects or indicates the area-based individual application of medium to the relevant side of the web or the property dependent thereon.
21. Machine according to Claim 20, characterized in that the control device comprises a drive device (70) which, on the basis of at least a first control output (X_S) from the first controller (60) and at least a second control output (X_Δ) from the second controller (62), drives the applicator or the applicators with the effect of a distribution of a total application, provided by the first control output (X_S) and relating to the two sides of the web, to two individual applications in each case relating only to one side of the web, in accordance with the second control output (X_Δ).
22. Machine according to one of Claims 1 to 21, characterized in that the sensor arrangement comprises at least two weight per unit area sensors (14, 16), of which at least one registers the weight per unit area (M_base) of the web before the application and at least one other registers the weight per unit area (M_total) of the web following the application to both sides, and in that one/the determination device (20) is designed to determine the area-based total application of medium to both sides of the web, in particular the total coat weight (M_S), from the weights per unit area before and after the application.
23. Machine according to one of Claims 1 to 22, characterized in that the sensor arrangement associated with at least one of the sides of the web, preferably associated with both sides of the web, (in each case) comprises at least one sensor (50, 52; 50', 52') responding in particular optically reflectively to the area-based individual application of medium to the associated side of the web and/or to at least one property of the web that depends on the area-based individual application of medium to the associated side of the web, in particular a gloss sensor (50, 52) or colour sensor or whiteness sensor.
24. Machine according to one of Claims 1 to 23, referring back to Claim 3 or 8, characterized in that one/the determination device (54; 54'; 54") is designed to determine a relation, in particular a difference or a ratio, between a variable relating to one side of the web and representing the property of the web that depends on the area-based individual application of medium to this side of the web and a variable relating to the other side of the web and representing the property of the web that depends on the area-based individual application of medium to this side of the web, if appropriate a whiteness ratio or gloss ratio or a whiteness difference or gloss difference (ΔG; Δ).
25. Method for determining area-based individual applications of medium during the application of a liquid or pasty medium by means of at least one applicator (12; 12a, 12b) to both sides of a moving web (10), in particular of paper or board, in which at least one output (M_base, M_total) which represents or reflects or indicates the area-based total application of medium to both sides of the web or a variable dependent thereon is received from a sensor arrangement (14, 16) and, on the basis of this output and a distribution value (K) representing a distribution relation of the area-based total application to the two sides of the web, the area-based individual applications (M_S,u, M_S,l) of medium for the two sides of the web are determined.
26. Method according to Claim 25, characterized in that at least one further output (G_U, G_L; S_U,1, S_L,1) which represents or reflects or indicates the area-based individual application of medium to one side of the web or a variable dependent thereon is received from the sensor arrangement and, on the basis of this output, the distribution value (K) representing the distribution relation of the area-based total application to the two sides of the web is determined.
27. Method for the application of a liquid or pasty medium by means of at least one applicator (12; 12a, 12b) to both sides of a moving web (10), in particular of paper or board,
    in which at least one output which represents or reflects or indicates the area-based total application of medium to both sides of the web or a variable dependent thereon is received from a sensor arrangement (14, 16, 50, 52; 14, 16, 50', 52') and, on the basis of this output, the area-based total application (M_S) of medium to both sides of the web is brought at least close to a predefined or predefinable total set point by driving the at least one applicator,
    characterized in that
    at least one further output (G_U, G_L; S_U,1, S_L,1) which represents or reflects or indicates the area-based individual application of medium to one side of the web or a property dependent thereon is received from the sensor arrangement and, on the basis of this output, in combination with the output (M_base, M_total) which represents or reflects or indicates the area-based total application of medium to both sides of the web or the variable dependent thereon, in each case the area-based individual application of medium is individually brought at least close to a predefined or predefinable respective individual set point by driving the applicator or the applicators for both sides of the web.
28. Method according to Claim 27, characterized in that, on the basis of the at least one output (M_base, M_total) from the sensor arrangement which represents or reflects or indicates the area-based total application of medium to both sides of the web or the variable dependent thereon, and a distribution value (K) representing a distribution relation of the area-based total application to the two sides of the web, the area-based individual applications (M_S,u, M_S,l) of medium for the two sides of the web are determined.
29. Method according to Claim 28, characterized in that, for both sides of the web, on the basis of the area-based individual application (M_S,u, M_S,l) determined for the respective side, the area-based individual application of medium is individually brought at least close to the predefined or predefinable respective individual set point by driving the applicator or the applicator assigned to the side.
30. Method according to Claim 28 or 29, characterized in that, on the basis of the further output (G_U, G_L, S_U,1, s_L,1) which represents or reflects or indicates the area-based individual application of medium to the relevant side of the web or the variable dependent thereon, the distribution value (K) representing the distribution relation of the area-based total application to the two sides of the web is determined.
31. Method according to one of Claims 27 to 30, characterized in that, for both sides of the web, the respective individual set point (M_S,u,SP, M_S,l,SP) for the area-based individual application of medium is predefined.
32. Method according to Claim 31, referring back to Claim 29, characterized in that driving the applicator or the applicators assigned to the two sides of the web in order to bring the area-based individual applications of medium close to the predefined or predefinable respective individual set point results in the area-based total application of medium to both sides of the web coming close to the total set point corresponding to the sum of the individual set points.
33. Method according to one of Claims 27 to 31, characterized in that the total set point (M_S,SP) for the area-based individual application of medium is predefined.
34. Method according to Claim 33, characterized in that the respective individual set point (M_S,u,SP, M_S,l,_SP) for the area-based individual application of medium is determined on the basis of one or of the distribution value (K; K_SP) representing an intended distribution relation of the area-based total application to the two sides of the web.
35. Method according to Claim 34, characterized in that an intended distribution value (K_SP) to be distinguished from the distribution value determined is predefined as the distribution value representing the intended distribution relation.
36. Method according to one of Claims 27 to 33, characterized in that, in relation to at least one side of the web, for at least one property of the web that depends on the area-based individual application of medium and to which at least one sensor of the sensor arrangement assigned to a relevant side of the web responds, an intended property or at least one intended relation to another property of the web is predefined.
37. Method according to one of Claims 27 to 33, characterized in that, in relation to the two sides of the web, for at least one property of the web that depends on the area-based individual application of medium to the respective side and to which at least one sensor (50, 53) which is assigned to the respective side of the web responds, an intended property or at least one intended relation to another property of the web or an intended relation (Δ_SP) between the property that depends on the area-based individual application of medium in relation to the one side of the web and the property that depends on the area-based individual application of medium in relation to the other side of the web is predefined.
38. Method according to Claim 36 or 37, characterized in that, on the basis of the predefined intended property or intended relation and the further output which represents or reflects or indicates the area-based individual application of medium to the relevant side of the web or the property dependent thereon, the property registered by the respective sensor is brought at least close to the predefined or predefinable intended property or to fulfilment of the predefined or predefinable intended relation by driving the applicator or the applicator assigned to the side in relation to the area-based individual application of medium.
39. Method according to Claim 36 or 37, referring back to Claim 33, characterized in that, on the basis of the total set point (M_S,SP) for the area-based individual application of medium and the output (M_base, M_total) which represents or reflects or indicates the area-based total application of medium to both sides of the web or the variable dependent thereon, bringing the area-based total application (M_S) of medium to both sides of the web at least close to the predefined or predefinable total set point is effected by outputting at least a first control output (X_S) and at the same time, on the basis of the intended property or intended properties or intended relation (Δ_SP) or intended relations and the further output (G_U, G_L) which represents or reflects or indicates the area-based individual application of medium to the relevant side of the web or the property dependent thereon, bringing the property registered by the at least one sensor or the sensors at least close to the predefined or predefinable intended property or to fulfilment of the predefined or predefinable intended relation (Δ_S) is effected by outputting at least a second control output (X_Δ).
40. Method according to Claim 39, characterized in that, on the basis of the first control output (X_S) and the second control output (X_Δ), the applicator (12) or the applicators (12a, 12b) is/are driven with the effect of a distribution of a total application, provided by the first control output (X_S) and relating to the two sides of the web, to two individual applications in each case relating only to one side of the web, in accordance with the second control output (X_Δ).
41. Method according to one of Claims 25 to 40, characterized in that the sensor arrangement comprises at least two weight per unit area sensors (14, 16), of which at least one registers the weight per unit area (M_base) of the web before the application and at least one other registers the weight per unit area (M_total) of the web following the application to both sides, and in that the area-based total application of medium to both sides of the web, in particular the total coat weight (M_S), is determined from the weights per unit area before and after the application.
42. Method according to one of Claims 25 to 41, characterized in that the sensor arrangement associated with at least one of the sides of the web, preferably associated with both sides of the web, (in each case) comprises at least one sensor (50, 52; 50', 52') responding in particular optically reflectively to the area-based individual application of medium to the associated side of the web and/or to at least one property of the web that depends on the area-based individual application of medium to the associated side of the web, in particular a gloss sensor (50, 52) or colour sensor or whiteness sensor.
43. Method according to one of Claims 25 to 42, characterized in that a relation, in particular a difference or a ratio, between a variable relating to one side of the web and representing the property of the web that depends on the area-based individual application of medium to this side of the web and a variable relating to the other side of the web and representing the property of the web that depends on the area-based individual application of medium to this side of the web is determined, if appropriate a whiteness ratio or gloss ratio or a whiteness difference or gloss difference (ΔG; Δ).

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